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User's Guide to AutoProbe CP - Advanced Processors Technologies

1. 100 120 220 240 VAC 50 60 Hz 400W Complies with 21 CRR 1040 10 and1040 11 Made in the USA AEM FMTHERMOMICROSCOPES 1171 Borregas Ave Sunnyvale CA 94089 1304 SSS AutoProbe Electronics Module Model No APEM 1000 mag Date Serial No Dr sy Patents 5 157 251 5 210 410 5 376 790 5 448 399 CE Figure 0 7 Panneau arri re du AEM montrant la position de l tiquette de conformit concernant la s curit du laser lv Preface and Overview Configuration du Systeme Standard Multitask Mesures de performance Scanner Aire de balayage Resolution de contr le Scanner Aire de balayage R solution de contr le Etage du microscope Course de translation Taille d chantillon Approche pointe chantillon Microscope optique Isolation acoustic Caract ristiques et performances pour l AutoProbe CP Inclus une t te de microscope pour des op rations en mode AFM En option la t te de microscope AFM NC AFM peut tre achet e pour des operations en modes AFM non contact contact intermittent et MFM En option la t te de microscope AFM LFM peut tre achet e pour des op rations en modes AFM et LFM En option le kit d outils STM peut tre achet pour des op rations en mode STM Inclus une t te de microscope multitask pour des op rations dans les modes suivants AFM contact non contact contact intermittent MFM LFM et STM scanner piezo lectrique Sum
2. 1 4 Reg ired EoMponents sr 2 0 2 e E Ea E E E 1 5 Taking an NC AFM Image sisi 1 6 Summary of the Procedure ss 1 6 Setting Up the Systemes ments t s h ee S EEES A ESERE AR e 1 8 Conneeting Eablesaur tan reset 1 8 Installing the Scanner 1 9 Loading a Sample nn tr Ernie 1 9 Installing the Probe Head and Probe Cartridge n 1 9 Configuring the Software ss 1 10 Aligning the Deflection Sensor 0 eee cee cee cseeereeeeeeeeeeeeeeeeees 1 11 Setting NCM Parameters ss 1 14 Selecting a Drive Amplitude u uuesseesnesnnesnnesnnesnnesnensnennnensnennen 1 14 Selecting a Drive Frequency 1 16 Selecting an Imaging Amplitude 1 18 Performing an Auto Approach 1 20 Setting Scan Parameters nenne 1 22 Selecting a Scan Size 1 23 Selecting a Scan Rates nine ie tisane 1 24 Setting the Gain fine nr ir ant tes 1 24 Adjusting the X and Y Slope u22u02200ssersnersnenseennennnennneennennenn 1 25 Starting A SCAN se UT eee A AE A 1 25 Avoiding Snap ins and Glitches ss 1 26 Taking an TC APM Mage intense nt inst tn a 1 27 Summary of the Procedure ss 1 27 Setting Up th System are cease tee 1 28 Setting NCM Parameters iis set er saesblenssshssennenesn 1 28 Selecting a Drive Amplitude 1 28 Selecting
3. Spectroscopy from the Mode menu or by clicking the Spectroscopy icon e on the Toolbar When you enter Spectroscopy mode the Image Gallery on the right side of the Image mode and Move mode windows is replaced by the Spectroscopy window The Spectroscopy window includes a graph and software controls as shown in Figure 5 1 below Note The Image Gallery buffers remain accessible at the bottom right side of the window ProScan HI SPS INSTR CP OFF EC STM HDM AFMSTM HD 5UM SCN AIR TEP Jox Fild Mode Setup Tools Help t __ V Head ON SSeS oo eee oe Move mode 500 700 Adi i 11V Image mode N v High voltage 4 Low voltage i i je er ern i J Spectroscopy ye Lov 100 mvidiv 1 v Save to buffer V Two way scan i i an l 1 AC 200 nm i I l 0 mA H F Topography Alt i 1 1 Slope DX y Repeat OLON BA Caley zoom ee 0 Scan OFF Image Import jaa opy Loa ave From To V Rate Hz Average Buffer Size u X offset u Y offset u Zm amp 11 10 10 1 Le 10 H o 2 0 0 bee ee nn a Scan rate SetP nA Servo gain 1 0 5 0 01 Zservo Smpl bias 1 2 um div 512 buffer lines allocated 7 Press F1 for Help dx 01 0000 dy 01 0000 dz 00 0000 Figure 5 1 The l V Spect
4. Note If you have a MAP module connected to your system be sure that the module is turned off before you attempt to apply an electrostatic bias to the sample To make electrical contact between the tip and the sample do the following 1 Paint an electrical connection between the sample and the sample holder using graphite paste or silver paint Alternatively you can use conductive double sided tape or the clips provided as part of your MFM toolkit to attach your sample to the MFM sample holder 2 After you have mounted the sample use a multimeter to check that the sample is electrically connected to the sample holder The magnitude of the bias you should apply depends on the particular tip and sample combination you are using The system software enables you to apply a bias in the range of 10 to 10 V Usually applied biases are in the range of 0 5to 2 V As an example if you are taking an image of the magnetic hard disk sample included in your MFM toolkit you might start with an applied bias of 0 5 V 1 54 Chapter 1 NC AFM IC AFM and MFM Imaging The procedures for applying an electrostatic bias to the sample to improve MFM or NC AFM images of magnetic samples are similar In general you iteratively vary the Sample Bias and set point parameters until the signal trace you are interested in is optimized Following are procedures for applying a bias to the sample assuming you are taking an NC AFM image of a magnetic samp
5. To increase the starting value successively click the scrollbox arrow of the button To decrease the starting value successively click the scrollbox arrow of the button Adjust the units per grid division of the horizontal scale This value is displayed on the right side of the current vs voltage curve To increase the number of units per grid division successively click the scrollbox arrow of the button To decrease the number of units per grid division successively click the scrollbox arrow of the button To adjust the vertical scale Select the V Vertical option button This selects the vertical scale to be adjusted Adjust the starting value of the vertical scale This value is displayed at the bottom of the current vs voltage curve To increase the starting value successively click the scrollbox arrow of the button To decrease the starting value successively click the scrollbox arrow of the button Adjust the units per grid division of the vertical scale This value is displayed at the top of the current vs voltage curve To increase the number of units per grid division successively click the scrollbox arrow of the button To decrease the number of units per grid division successively click the scrollbox arrow of the button Acquiring Current vs Voltage Data 5 11 Zooming in on a Region of Interest Often times you will want to zoom in on a particular portion of an I V curve you have generated You can do t
6. 1 Click the Scale scrollbox arrow to expand the horizontal scale Successively clicking the scrollbox arrow decreases the units per division and may also increase the starting value of the horizontal scale The units per division for the horizontal scale are displayed at the right side of the graph Note You can prompt the system to re scale the axes automatically at any time by clicking the button 2 If you expand the horizontal scale too much you can reduce it again by clicking the Scale scrollbox arrow 3 Click the Scale scrollbox arrow to expand the vertical scale Successively clicking the scrollbox arrow decreases the units per division The units per division of the vertical scale are displayed at the top of the graph 4 If you expand the vertical scale too much you can reduce it again by clicking the Scale scrollbox arrow You can also shift the position of the F vs d curve on the graph without changing the scale using the Offset scrollbox arrows 5 Shift the curve to the left by clicking the Offset scrollbox arrow Successively clicking the Offset scrollbox arrow increases the starting value of the horizontal axis shifting the curve to the left on the graph 6 Shift the curve to the right by clicking the Offset scrollbox arrow Successively clicking the Offset scrollbox arrow decreases the starting value of the horizontal axis shifting the curve to the right on the graph 7 Shift the curve up by cli
7. This section includes steps for configuring the system software for taking an STM image Open ProScan Data Acquisition From Start point to the Program folder and select ThermoMicroscopes ProScan Then click the Data Acquisition icon Alternatively double click the Data Acquisition icon in the desktop The program opens to Move mode Turn off the probe head by either deselecting Head ON from the Mode menu or clicking the Head ON icon J Open the ProScan database configuration dialog box by selecting Configure Parts from the Setup menu Taking an STM Image 2 15 4 In the ProScan Database Configuration dialog box make the following selections to configure the system software for STM operation Head type AFMSTM Scanner Select the file that has the scanner calibration values for the scanner that you are using Head mode STM Tunneling tip AIR Electrochemistry ON OFF OFF Voltage mode HI After you finish making these selections click to return to Move mode 5 If you have not already done so reset the Z stage as described in Chapter 2 Part I of this User s Guide This synchronizes the position of the Z stage with the coordinate system of the software Diagnostic Checks This section includes steps for checking electrical connections and tip to sample bias offsets 1 Using a multimeter on the Ohms setting check the electrical resistance of the path between the STM t
8. keep the tunneling current constant by raising or lowering the sample Since the tunneling current varies exponentially with tip to sample spacing the set point value basically controls the tip to sample spacing during a scan Raising the set point value brings the tip closer to the sample while lowering the set point value moves the tip farther from the surface Ideally the tip should never come into contact with the surface during an STM scan because both the tip and the sample surface will be damaged For instance the tip can leave a small pinhole or dent in the surface if it is driven into the surface Typically the set point is less than 10 nanoamps for STM The tip to sample bias during a scan is set using the sample bias and tip bias parameters If the sample is biased negative relative to the tip then the STM image will represent tunneling from filled electronic states on the sample surface If the sample is biased positive relative to the tip then the STM image will represent tunneling into empty electronic states on the sample surface The tip and sample biases are given in volts The bias settings do have an indirect effect on the tip to sample spacing In constant current mode with feedback optimized the system attempts to maintain a constant tunneling current by varying the tip to sample spacing If the tip to sample bias is increased the tunneling current also increases The system therefore pulls the sample away
9. specific legal rights and you may also have other rights which vary from state to state Manufacturer Information AutoProbe CP systems contain no user serviceable parts All service issues should be addressed to your local ThermoMicroscopes representative ThermoMicroscopes USA ThermoMicroscopes USA 1171 Borregas Avenue 6 Denny Road No 109 Sunnyvale CA 94089 Wilmington DE 19809 T 408 747 1600 T 302 762 2245 F 408 747 1601 F 302 762 2847 ThermoMicroscopes SA ThermoMicroscopes Korea 16 rue Alexandre Gavard Suite 301 Seowon Building 1227 CAROUGE 395 13 Seokyo dong Mapo ku Geneva Switzerland Seoul Korea T 41 22 300 4411 T 82 2 325 3212 F 41 22 300 4415 F 82 2 325 3214 If you return system components to ThermoMicroscopes for service that have come into contact with harmful substances you must observe certain regulations Harmful substances are defined by European Community Countries as materials and preparations in accordance with the EEC Specification dated 18 September 1979 Article 2 For system components that have come into contact with harmful substances you must do the following Decontaminate the components in accordance with the radiation protection regulations Construct a notice that reads free from harmful substances The notice must be included with the components and the delivery note xxiii How to Use This User s Guide The User s Guide to AutoProbe CP is divided into
10. surface and intermittent contact is consequently achieved How Magnetic Force Microscopy Works 1 61 How Magnetic Force Microscopy Works The interatomic force vs distance curve of Figure 1 6 was central to the explanation of non contact AFM The figure illustrates how the force gradient changes with tip to sample spacing Since the force gradient affects the cantilever s resonant frequency as shown by Equations 1 and 2 vibrating cantilever methods can use measured changes in the cantilever s resonant frequency to maintain a constant tip to sample spacing and thereby monitor and image changes in sample topography The underlying principles of MFM are similar to those of NC AFM and their explanation also benefits from a diagram of the interatomic force vs distance relationship For the case of MFM a magnetized tip is used and forces between this magnetic tip and magnetic domains on the sample surface must be included on the force vs distance curve Figure 1 9 shows an interatomic force vs distance curve for a typical sample and tip used to take an MFM image e g a magnetic storage disk and a cantilever tip coated with sputtered cobalt The figure shows that magnetic forces Fm are superimposed upon the van der Waals forces Fy which are still present A Force F Fm repulsive gt distance z i Fm attractive Figure 1 9 Interatomic force vs distance curve showing both magnetic forc
11. This section includes warnings and cautions that must be followed whenever you operate AutoProbe CP WARNING AutoProbe CP must be properly grounded before you turn on the power to its components The mains power cord must only be inserted into an outlet with a protective earth ground contact See the section Grounding AutoProbe CP later in this preface for more information WARNING The line voltage selection must be checked before you turn on the power to AutoProbe CP s system components The line voltage selector switch is on the rear panel of the AEM The line voltage selector switch can be set to the following voltages 100 V 120 V 220 V and 240 V See the section Setting the Line Voltage later in this preface for more information WARNING Do not open the AutoProbe electronics module AEM or the CP base unit The AEM and the CP base unit use hazardous voltages and therefore present serious electric shock hazards WARNING ThermoMicroscopes requires that you routinely inspect the cables of the AutoProbe CP system to make sure that they are not frayed loose or damaged Cables that are frayed loose or damaged must be immediately reported to your local ThermoMicroscopes service representative Do not operate AutoProbe CP when wires are frayed loose or damaged xii Preface CAUTION All AutoProbe CP system components must be handled with care System components contain delicate electromech
12. V yi How Intermittent Contact AFM Works 1 60 How Magnetic Force Microscopy Works 1 61 Using an Electrostatic Bias nes 1 63 Hardware Components for Non Contact Imaging uursessesssessnesnnennnensnenseenne nenn 1 65 S MAT YEN sea OA ie cop A R Sc Ds A peut ee eA ROR AR 1 68 Introductio issue ER ES BE ER BE en 2 2 Preparing and Loading STM Tips 2 3 Using Wire Cutters to Make STM Tips 2 3 Using ThermoMicroscopes s Tip Etcher nennen nn 2 4 Setting Up the Tip Etcher wee eee cece cssecsseesecssecssecseeceseeeeeeeees 2 5 Operating the Tip Etcher ss 2 6 Using the STM Cartridge un ine en mA nl teens 2 8 Inserting the STM Tip into the STM Cartridge 2 9 Taking an STM Im ge 5 2 hei addins r a he nd oe eR 2 12 Setting Up the Systems EM nat ren pue 2 13 Setting Up Hardware i here antterhasnerne 2 13 Configuring the Software ss 2 14 Diagnostic Checks Ran Nenn 2 15 Approaching the Sample x2 2 3 32 8 2 82a 2 17 Setting Up for an Auto Approach 2 17 Performing an Auto Approach ss 2 20 Starin a SCAN net Sie hae Pen ete ne Geechee innere 2 21 Optimizing STM Scan Parameters 22s22242 2442 2nensennensnensnensennnnnnennnennnenn 2 22 Constant Current vs Constant Height Mode 00 0 ceecseeeseeeeeeeeeenees 2 23 Taking a Constant Current Mode Image 2 24 T
13. sample spacing to maintain a constant vibration amplitude of the cantilever Since the set point parameter also affects the tip to sample spacing the set point and Sample Bias parameters are coupled You must adjust them iteratively to find the set point and applied bias combination that optimizes the Topography signal trace You should also try to optimize the gain so that the system is not oscillating but is sensitive enough to track the set point closely Ideally the Sample Bias value you set should not be too high since the bias effectively charges the sample surface and may map dielectric rather than topographic features This is especially true for natural magnetic samples whose surfaces may be less dielectrically homogeneous Where to Go From Here 1 55 Where to Go From Here This concludes the tutorial sections of this chapter At this point you can review the tutorials and practice taking images until you feel confident using vibrating cantilever techniques If you are interested you may want to continue and read the next sections which discuss underlying principles of NC AFM IC AFM and MFM imaging 1 56 Chapter 1 NC AFM IC AFM and MFM Imaging How Non Contact AFM Works This section describes the principles underlying NC AFM operation These principles are referred to in later sections as they are applicable to IC AFM and MFM operation as well Every cantilever has its own characteristic resonant frequency
14. Balayage lat ral maximum Sum Balayage vertical maximum 2 5um R solution lat rale maximum 0 0013 R solution verticale maximum 0 009 Scanner piezo lectrique 100 um Balayage lat ral maximum 100um Balayage vertical maximum 7 5um R solution lat rale maximum 0 25 R solution verticale maximum 0 025 8 mm x 8 mm 50 mm w x 50 mm 1 x 25 mm h pour une configuration standard 50 mm w x 50 mm 1 x 20 mm h pour une configuration multitask Automatique avec 3 moteurs pas pas ind pendants En option microscope droit avec moniteur vid o couleur pour la visualisation de la pointe et de l Echantillon En option chambre d isolation acoustique Station de travail AEM Ordinateur Mass storage Memoire de masse Logiciel Graphiques Alimentation Dimensions et poids Unit de base CP AEM Ordinateur Conditions d utilisation Temperature Humidit Entretien Unit de base CP T te de microscope AEM et ordinateur Ivii DAC 20 bit pour la commande des axes x y et z DAC 16 bit pour le syst me de contr le Processeur Pentium 133 MHz 256 Kbyte de m moire cache 16 MB RAM 1 GB hard drive 3 1 2 in 1 4 MB floppy disk drive Disque dur 1 GB lecteur de disquette 3 5 1 4 MB Proscan Data Acquisition et Image Processing fonctionnent sous Windows 95 Carte graphique acc l ratrice Windows moniteur couleur 17 h
15. DetMicronPerAdc_SZ needs to be changed The correct z detector calibration value is the existing value multiplied by the ratio of correct to measured distances correct distance correct cal value existing cal value x 8 measured distance 1 For example if you ask the software to measure a distance that you know is 0 2 um and it produces a value of 0 16 um and the existing DetMicronPerAdc_SZ value is 20 then you should change the value as follows DetMicronPerAdc_SZ 20 x a 25 0 7 Enter the correct value for the DetMicronPerAdc_SZ parameter in the table you created earlier for the three detector calibration parameters Note When the existing DetMicronPerAdc_SZ value is negative be sure to retain the negative sign in entering any corrections Next you will enter the corrected DetMicronPerAdc_SZ parameter value into the scanner calibration parameter file 6 36 Chapter 6 Scanner Calibration Editing the Scanner Calibration File 1 From the Move mode window use the z direction pad to withdraw the tip from the sample 2 Turn off the probe head by either deselecting Head ON from the Mode menu or clicking the Head ON icon 3 Select Calibration Edit from the Setup menu Click in the Warning box to indicate that you want to proceed 4 Select the Scanner Det category in the left listbox 5 Select DetMicronPerAdc_SZ from the list of calibration parameter values 6 Change
16. If the frequency response curve saturates on the graph of the NCM dialog box then you need to decrease the drive amplitude Vary the value until the maximum peak height of the response curve is roughly one third of the full vertical scale on a zoomed out sweep 4 To change the drive amplitude enter a percentage in the Drive scrollbox of the NCM dialog box 5 Press the Enter key so that the software recognizes the change and click the button to see the change in the response curve You can also adjust the drive amplitude during a scan from within Image mode using the Drive scrollbox Selecting a Drive Frequency The drive frequency is the frequency of the AC signal from the sine wave generator that drives the cantilever vibration For an NC AFM image the drive frequency should be slightly greater than the frequency of the cantilever s main resonance peak When you prompt the system to generate a frequency response curve by clicking the button it automatically determines the maximum cantilever resonance peak The system then selects a single drive frequency lying just to the right of that peak for NC AFM operation within the top half of the peak at the point with the steepest slope This drive frequency is marked by a cross hair The cantilever s main resonance peak should be at around 100 kHz if you are using long NC AFM Ultralevers The cross hair should lie just to the right side of the peak The automatically s
17. Note Be careful not to drag the mouse as you click Clicking and dragging the mouse prompts the system to generate sixteen F vs d curves between two endpoints of a line Generating multiple curves along a line is discussed in a later section Acquiring Curves Along a Line 11 Drag the ends of the red Piezo Adjustment bar to be roughly symmetric about the Set Point arrow At this point you are ready to generate F vs d curves F vs d curves can be generated in two modes Run and Acquire Clicking the button prompts the system to continuously sweep the scanner generating F vs d curves that cannot be saved but that you can view as you adjust parameters For example you can adjust the scanner s sweep range or the sweep rate and watch the effects of these changes on curves as they are generated in Run mode Then once you have selected parameters to your satisfaction you can click the button to stop the scanner s sweeping Clicking the button prompts the system to generate one F vs d curve at a time and load that curve into a buffer where it can be saved Each curve is the average of the number of curves you selected to be averaged in the Spectroscopy Setup dialog box Parameter values cannot be changed while a curve is being generated in Acquire mode Start generating F vs d curves for parameter adjustment now in Run mode 12 Click the button to start sweeping the scanner and generating F vs d curves At any time you ca
18. Part II of this User s Guide Learning to Use AutoProbe CP Advanced Techniques includes hands on tutorials for operation in the following modes NC AFM IC AFM MFM STM and LFM It also includes tutorials that introduce you to advanced capabilities of AutoProbe CP such as force vs distance and current vs voltage data acquisition and scanner calibration Chapter 1 NC AFM IC AFM and MFM Imaging provides step by step instructions for taking NC AFM IC AFM and MFM images Chapter 1 also describes the principles behind NC AFM IC AFM and MFM modes of operation xxiv Preface Chapter 2 STM Imaging guides you through taking an STM image In this chapter you learn procedures for preparing an STM tip and using a STM cartridge setting up the hardware and software for operation in STM mode and taking an STM image Chapter 3 LFM Imaging leads you through taking simultaneous LFM and AFM images Chapter 3 also includes information on how LFM images are produced and the usefulness of having both LFM and AFM images available Chapter 4 Force vs Distance Curves describes how to use the F vs D Spectroscopy window of ProScan Data Acquisition to generate force vs distance curves at x y locations on the sample surface A force vs distance curve is a plot of the vertical force that the tip applies to the cantilever as a function of the tip to sample distance Variations in the shape of force vs distance curves provide infor
19. dominant over the magnetic force gradient 3 Decrease the gain parameter to stabilize the signal trace Taking an MFM Image 1 51 4 Iteratively decrease the absolute value of the set point and adjust the gain until the Topography signal trace is representative of topographic features on your sample s surface Obtaining an NC AFM image that reflects topographic information may be difficult if it requires operating very close to the sample surface where the tip may be more prone to snap ins For these cases you may want to try applying an electrostatic bias to the sample which increases the range of the topography dependent force gradient To learn about applying a bias to the sample skip to the next section Applying an Electrostatic Bias Between the Tip and the Sample Another approach to collecting follow up topographic images is to switch to contact AFM mode and take an image If ScanMaster is on the scan area can be repeated accurately To switch to contact AFM mode and take an image of sample topography do the following 5 Turn off the probe head by either deselecting Head ON from the Mode menu or clicking the Head ON icon 6 Select Config Parts from the Setup menu to open the Configure Parts dialogue box 7 Under Head Mode select AFM 8 Click to return to Image mode 9 Set scan parameters and perform an auto approach as described in Part I of this User s Guide Note You
20. located on one end of the scanner tube is for monitoring the xy position of the scanner This detector is connected to a feedback loop that is enabled if ScanMaster is turned on The xy position is read and the information is compared to a reference value representing the intended xy position A voltage is then sent to the scanner to correct its position You can turn ScanMaster on or off using software controls If ScanMaster is off then the xy feedback loop is disabled and no correction is applied to the scanner s xy position Calibrating a 100 Micron Scanner 6 25 Z detection differs from xy detection in that it is not connected to a feedback loop This is because there is no intended z position as there is for the xy position of a raster pattern since the z position reflects sample topography AutoProbe systems that have the sample mounted on the scanner i e scanning sample systems are equipped with two z detectors These detectors are located on the left and right sides of the scanner tube and measure both the extension and the tilt of the scanner The signals from these two detectors are averaged to produce a single Z Detector signal which reflects the z position of the scanner AutoProbe systems that have the probe mounted on the scanner i e scanning probe systems are equipped with a single z detector The signal from this detector is used to produce the Z Detector signal For some applications the Z Detector signal
21. optimales Partie Ill R ferences du logiciel La partie III de ce guide de l utilisateur References du logiciel est un manuel de r f rence pour ProScan Data Acquisition and Image Processing et comprend des informations pour les syst mes AutoProbe suivant CP LS et M5 Les chapitres de cette partie du guide de l utilisateur vous donnent des informations plus d taill es sur certaines caract ristiques et contr les les informations qui vous sont donn es dans les chapitres de formation pratique Les chapitres sont congus de telle sorte que vous puissiez allez directement aux caract ristiques et contr le sur lesquels vous d sirez apprendre quelque chose Ixiii Le chapitre 1 ProScan Data Acquisition d crit en d tail les caract ristiques du logiciel ProScan Data Acquisition Ce chapitre traite chaque portion de l cran pr tant une attention sp ciale chaque possibilit de contr le et ses fonctions Ce chapitre traite galement des menus avec une description de chaque article du menu et de sa fonction Le chapitre 2 Traitement d image ProScan d crit en d tail les caract ristiques du logiciel ProScan Image Processing Ce chapitre explique comment obtenir des images comment faire des mesures de surface et comment pr parer les images pour l impression sous diff rents formats Part Il Learning to Use AutoProbe CP Advanced Techniques Chapter 1 NC AFM IC AFM and MFM Imag
22. rate gain and slope parameters as you normally do to optimize the Topography signal trace for a contact AFM image 6 Click the button to take a contact AFM image Make sure that the grid lines of the calibration sample are aligned with the x and y scan directions If they are not aligned lift the tip rotate the sample re approach the sample and take another image Repeat this process until the grid lines are aligned with the x and y scan directions 7 Once you have obtained a satisfactory image use the Line Analysis software tools described in the Image Processing chapter of Part III of this User s Guide to flatten the image and measure a known distance along the x axis For Calibrating a 100 Micron Scanner 6 33 example measure the distance between 10 grid lines which corresponds to 89 1 um 8 Compare the measured distance value to the known distance value Ifthe distance produced by the software measurement tools is incorrect then the detector calibration value along the x axis DetMicronPerAdc_SX needs to be changed At this point it is recommended that you create a table listing the names of the three calibration parameters that you will be calibrating manually Include spaces for the values of the calibration parameters Keep this table for future reference After you have completed the scanner calibration procedure you will save a copy of the scanner calibration parameter file As mentioned earlier if you ne
23. scanner For example a file for a 5 um scanner with the serial number 0123 would have the file name 5_123 scn You may also have default scanner calibration parameter files under the drop down list in the CP LS Scanner category of the ProScan Database Configuration dialog box These default files contain typical calibration parameters for a particular model of scanner or scan head These default files cannot be used as working files unless scanner calibration is performed The default value for many of the parameters is listed as Invalid which 6 8 Chapter 6 Scanner Calibration means that a value has not yet been determined However the default files can be used after calibration has been performed The default scanner calibration files should be left in the c psi cal directory as a backup in case the files for specific scanners become corrupted The file name for a default file will typically include the size of the scanner For example a default file for a5 um scanner would have the file name 5um scn If for some reason you need to perform the scanner calibration procedure using a default file you should make a copy of the default file and work with the copy By doing this you will retain an uncorrupted default file as a backup To copy a default scanner calibration parameter file Open the Explorer and then open the directory c psi cal Make a copy of the default scanner calibration parameter file for the appropria
24. scanner within its total range of motion The Z Piezo bar should show the scanner extending as you decrease the set point value since the system is decreasing the tip to sample spacing as it attempts to match the lower set point value If you see that the system is extending the scanner fully in its attempt to match the set point value then you need to re approach the sample Re approaching allows the system to use the motorized Z stage to decrease the tip to sample spacing Continue to incrementally decrease the set point value while watching both the Topography signal trace and the Z Piezo bar Re approach the sample if necessary to position the scanner so that it is at the middle of its range of z extension when the auto approach stops 1 42 Chapter NC AFM IC AFM and MFM Imaging Depending on the interaction between the tip and sample you are using and on the value ofthe gain parameter you may see oscillations spikes or glitches appear on the Topography signal trace as you decrease the set point value Oscillations can occur if the gain value is too high for the tip to sample spacing corresponding with the set point value If this is the case the system may overreact as it attempts to maintain a constant force gradient causing it to oscillate Spikes or glitches can result if the tip is pulled into contact with the sample by strong magnetic forces In some cases you can use the appearance of oscillations or spikes to help
25. which depends on its dimensions and the material used to fabricate it A cantilever vibrates naturally at this resonant frequency Thermal vibrations or a bump on the table for instance can start these oscillations Non contact AFM uses detection of a cantilever s resonant frequency as an indirect measure of sample topography This section describes the correlation between cantilever resonance and sample topography and it explains how NC AFM images of topography are produced Figure 1 6 shows an interatomic force vs distance curve which illustrates the force between atoms on a cantilever tip and atoms on a sample surface vs the separation distance between the tip and the sample Two distance regimes are labeled on the figure 1 the contact regime less than a few angstroms which represents the tip to sample spacing for contact AFM and 2 the non contact regime ranging from tens of angstroms to hundreds of angstroms which represents the tip to sample spacing for NC AFM In the contact regime the interatomic forces are repulsive while in the non contact regime they are attractive and largely a result of long range van der Waals interactions A force repulsive force iT contact Distance tip to sample separation Non contact i attractive force Figure 1 6 Interatomic force vs distance curve How Non Contact AFM Works 1 57 NC AFM is desirable because it provides a means for measuri
26. AFM switch to the LFM position 8 Align the deflection sensor as described in Chapter 2 Part I of this User s Guide 9 Perform a coarse approach by using the z direction pad to move the tip to within a few millimeters of the sample surface Then click the button to initiate an auto approach Once the auto approach is complete you are ready to begin calibrating the detectors Calibrating the XY Detector Manual calibration of the ScanMaster detectors is an important step of the scanner calibration procedures since the auto calibration procedures that calibrate the detector offsets and the scanner sensitivity use positions reported by the ScanMaster detectors This section describes the procedures for calibrating the xy detector Since the detectors are not affected by the range of volts to the scanner this calibration procedure only needs to be performed in high voltage mode The XY Detector Calibration Parameters The detector calibration values for the x and y directions are labeled DetMicronPerAdc_SX and DetMicronPerAdc_SY respectively The values are given in units of microns per Adc where Adc units are defined as follows Each detector produces an analog voltage value that represents scanner position An analog to digital converter adc then converts this analog voltage to a digital number Thus the signal from a detector is the digital output from an adc 6 32 Chapter 6 Scanner Calibration The full volt
27. Contact AFM Image 2 Open the F vs d Spectroscopy window by either selecting Spectroscopy from the Mode menu or by clicking the Spectroscopy icon on the Toolbar The Spectroscopy window opens on the right side of the screen Acquiring Force vs Distance Data 4 15 Click the LScan OFF button located next to the button in the Image mode window This stops rastering of the scanner for F vs d data acquisition The z feedback loop is still enabled Clicking the button enables the and buttons of the Spectroscopy window When you click the button it changes to the button If you click the button the scanner rasters once again and the and buttons are disabled Click the button to open the F vs d Setup dialog box Click the Z Detector option button to select the Z Detector signal as the variable to be plotted along the horizontal axis Note If you are using a 5 um scanner do not select the Z Detector signal since 5 um scanners are not equipped with detectors The Z Drive signal which is selected by default represents the volts sent to the scanner to set the scanner s z position The Z Detector signal represents the scanner s actual z position as measured by the z detectors Because of scanner nonlinearities plotting the Z Drive signal may result in hysteresis or an offset of the extension and retraction paths of the scanner along the horizontal axis Set the number of sweeps that will be used
28. Gebrauch des Benutzerhandbuches xliii Kapitel 1 STM Imaging f hrt sie durch das Aufnehmen eines STM Bildes In diesem Kapitel werden sie lernen eine STM Spitze zu preparieren eine STM Kartusche zu benutzen die Hardware und Sofrware f r die Aufnahmen von STM Bildern einzustellen und ein STM Bild aufzunehmen Kapitel 2 LFM Imaging f hrt sie durch das gleichzeitige Aufnehmen von LFM und AFM Bildern Kapitel 2 enth lt des weiteren Informationen dar ber wie LFM Bilder entstehen und ber den Nutzen beides LFM und AFM Bilder zur Verf gung zu haben Kapitel 3 NC AFM IC AFM and MFM Imaging beschreibt die Grunds tze hinter NC AFM IC AFM und MFM Betriebsart Kapitel 3 beinhaltet weiterhin schrittweise Anweisungen zur Aufnahme von NC AFM IC AFM und MFM Bilder Kapitel 4 Force vs Distance Curves beschreibt das Aufnehmen von Kraft Abstands Kurven an x y Orten auf der Probenoberfl che in ProScan Data Acquisition Eine Kraft Abstands Kurve ist die Dartellung der Vertikalkraft die die Spitze auf den Balken bertr gt als Funktion des Abstandes zwischen Spitze und Probe Unterschiede in der Form der Kraft Abstands Kurve lassen auf die rtliche Elastizit tskonstante der Probenoberfl che r ckschliessen Kapitel 5 I V Spectroscopy lernt ihnen das I V Spectroscopy Fenster in der ProScan Data Acquisition zu benutzen um eine Strom Spannungs Kurve I V und dI dV Kurven aufzunehmen Diese Kurven enthalten wertvolle In
29. Once all eight of the calibration parameters have numerical values the values of the four first order parameters are used by the system software and the two default first order calibration parameters are disabled Next you will take an AFM image of your calibration sample For details on taking an AFM image refer to Part I Chapters 2 through 4 of this User s Guide You will use measurements on this image to determine values for the first order calibration parameters Taking an Image and Determining Calibration Parameter Values This tutorial uses the 1 um gold calibration grating provided as part of your system as an example If you are using a different calibration standard simply substitute the known spacing value for your sample where that for the gold grating is referred to here Note If you will be taking atomic scale images frequently then you should use a calibration sample that has atomic scale features of known spacing such as 6 12 Chapter 6 Scanner Calibration HOPG highly oriented pyrolytic graphite Since values of the calibration parameters depend on scan size values obtained using a 1 um grating as a calibration standard can lead to inaccurate reporting of scan sizes for atomic scale images Turn on the probe head by selecting Head ON from the Mode menu or clicking the Head ON icon Perform a coarse approach by using the z direction pad to lower the probe head until the tip is within
30. Oscilloscope Display to start a scan You may need to adjust scan parameters while a scan is being taken to obtain an optimized image In non contact mode the vibrating cantilever should be brought as close as possible to the sample surface without touching This means operating with a small set point absolute value The closer the cantilever tip is to the surface the higher the lateral resolution will be However if the cantilever is brought too close the attractive force becomes strong enough to damp the cantilever vibration and even pull the tip down into the surface In addition if the amplitude is too small the system will not be able to track drop offs in sample topography and trailing edges of topographic features may not be resolved on an image 1 26 Chapter 1 NC AFM IC AFM and MFM Imaging Avoiding Snap ins and Glitches The most common problem when imaging in non contact mode is that the tip hits the surface If the tip is too close to the surface during a scan the strong attractive force can damp the vibrations When the tip is either hitting the surface or is too close to it glitches can occur in the signal trace on the Oscilloscope Display and the signal trace can become unstable If the tip is too close to the surface you can increase the absolute value of the set point parameter i e make it more negative to increase the tip to sample spacing If adjusting the set point value doesn t help then adjus
31. ScanMaster Works8 2 en seta EE E EREET Se 6 24 What it Means to Calibrate a 100 Micron Scanner 6 26 Scanner Calibration Procedures ss 6 27 Installing the System Hardware 6 27 Configuring the System Software uueenessnersnessnenseennennnnnnnnnnnennnnnn 6 28 Calibrating the XY Detector 6 31 Calibrating the Z Detector 0 eee cee cseecreeeeeeeeeeeeeeseeereeeeeeeeees 6 34 Auto Calibration of Detector Offsets and Scanner Sensitivity 6 36 Creating a Backup Scanner Calibration File un 6 38 Preface Operating Safety This section includes important information about your AutoProbe CP system It describes in detail procedures related to the operating safety of AutoProbe CP and therefore must be read thoroughly before you operate your AutoProbe CP system WARNING The protection provided by the AutoProbe CP system may be impaired if the procedures described in this User s Guide are not followed exactly Safety Symbols Table 0 1 lists symbols that appear throughout this User s Guide and on the AutoProbe CP system You should become familiar with the symbols and their function The symbols are used to alert you to matters related to the operating safety of the AutoProbe CP system Table 0 1 Safety symbols and their functions Symbol Function _ Direct current source ENG Alternating current source EL Direct and alternating current sourc
32. ThermoMicroscopes tip etcher to produce sharper STM tips See the section below for instructions for using the ThermoMicroscopes tip etcher You will need the following items 20 mil or 0 5 mm tungsten or Ptir wire astrong pair of wire cutters a pair of needle nose pliers To make a tip by cutting wire 1 First cut off a piece of wire between 1 and 1 5 long using a strong pair of wire cutters Ordinary wire cutters will be damaged 2 Grip one end of the wire tightly with a pair of needle nose pliers Orient the wire cutters at a 45 angle relative to the wire as shown in the figure below To cut the wire use the wire cutters to pull and twist the end of the wire while snipping 2 4 Chapter2 STM Imaging The resulting tip does not look sharp but actually is Tungsten STM tips oxidize fairly quickly and should be discarded after 1 to 2 days Platinum iridium STM tips on the other hand do not readily oxidize and may be kept and used for a much longer time Figure 2 1 Holding wire cutters at a 45 angle to cut an STM tip The overall shape of tips made using wire cutters is not well defined STM images taken using these relatively blunt tips can show multiple tip imaging effects Sharper higher aspect ratio tungsten tips can be made using a tip etcher as described below Using the ThermoMicroscopes Tip Etcher The instructions in this section explain how to set up the ThermoMicroscopes tip etcher and h
33. Up to Acquire an F vs d Curve nennen 4 9 Taking a Contact AFM Image enueennessnesnnesnnesnennnensnennnennn ernennen 4 9 Calibrating the Vertical F vs d Axis 4 11 Generating a Force vs Distance Curve ssseesseeessereereersreesrsreeresrrrrsrerrrerrsrene 4 14 Adjusting the Horizontal and Vertical Scales of an F vs d Curve s esesses 4 18 Zooming in on a Region of Interest 4 20 Zooming in Graphically Using the Cursor 20 nenn 4 20 Zooming in by Changing the Scanner s Sweep Range eeseeeeeeee 4 21 Making Point to Point Measurements on an F vs d Curve 4 22 Generating an F vs d Curve at a Different X Y Location 4 22 Acquiring F vs d Curves Along a Line 4 23 Saving Exporting and Printing Data 4 24 Redisplaying Curves in F vs d Spectroscopy nuuessessnessnesnnesnnesnnesnensnensnenn 4 25 Where to Go From Here 5 noi ae Gate ee sal hi Hae Ota eee 4 26 Forces Acting on the Cantilever H288422 20 essen 4 27 Understanding Force vs Distance Curves nenn 4 29 Cantilever Data Sheets u nennen esse 4 31 Mietolevers EEE RE ALT ER nn ne en ER RR 4 31 Uiltrale vers sers Ministre ne aha niin iat ease tete engen 4 32 Contents vil viii Chapter 5 l V SpectroSCOpy sd Introduction se Siecseadecte mt eke nine tte in Elek RI 5 2 The I V Spectroscopy Window naine sgeusberdbenso
34. You can also monitor the tunneling current signal which is used to generate the Error signal to the feedback loop When feedback is enabled the tunneling current should be constant An image of any remaining error gives a measure of how well the feedback loop is tracking the sample topography When the gain is set to a low value however the z feedback is minimal and the tunneling current varies with the topography and surface electronic structure of the sample Thus the tunneling current signal called the Error signal can be used to generate an image of the sample surface This mode of imaging is often called constant height mode because with minimal feedback the tip to sample spacing is not varied to maintain a constant tunneling current signal Constant height mode images can be taken faster than constant current mode images because feedback is minimized and the system does not have to wait for the response of the feedback loop This is important for small sized scans that need to be taken faster than the effects of thermal drift However because the z position of the scanner does not follow changes in surface topography constant height mode can only be used to take 2 24 Chapter 2 STM Imaging images of smooth surfaces Constant current mode can be used to take images of irregular surfaces but these images take longer to collect These characteristics of constant current mode and constant height mode images mean that you
35. You can enter the corrected values of the second order calibration parameters into this table as well 13 14 15 16 17 18 Calculate a new value for a scanner calibration parameter using the following formula correct distance measured distance 2 2nd O cal value i ne measured distance 1st O cal value For example if you ask the software to measure the distance between 5 maxima along the x axis of a fast x scan and it produces a value of 3 5 um and the value of the MicronPerDac_FastSX parameter is 3 33 then the value of the MicronPerDacSq_FastSxX calibration parameter is calculated as follows 4 3 5 MicronPerDacSq_FastSX 653 33 0 45 Record the value in the High Voltage column of your table of calibration parameter values Repeat Steps 11 through 14 measuring the spacing between grating lines along the y axis of the fast x image to calculate a value for the MicronPerDacSq_SlowSY parameter Next switch the fast scan direction to be the y direction Again correct the slope parameter so that the signal trace on the Oscilloscope Display is level The scan rate and scan size should be left the same Click the button to take an image with the y direction as the fast scan direction Repeat steps 11 through 14 measuring the distance between grating lines in the y direction of the fast y image to calculate a value for the MicronPerDacSq_FastSY parameter Calibrating a 5 Mic
36. a Drive Frequency 1 29 Selecting an Imaging Amplitude 1 31 Performing an Auto Approach 1 32 Setting Scan Parameter Soses aeia eae eee ea SITE EE 1 33 Starting a Scan dit nd Rite lines 1 33 Taking an MFM Tma geeen es Sth ER A RE M Hee ee 1 35 Summary of the Proc dure 235 n8nuennnt si nsteniiehiti 1 35 Setting Up thesystemi anne me nn AE Anh RAA 1 37 Loading a Sample 22022402200nsensennnennesnnennennnnnnnesnnennnennne nennen 1 37 Installing the Probe Head and Probe Cartridge 1 38 Configuring the Software 1 38 Aligning the Deflection Sensor 1 38 Setting NCM Parameters ss 1 39 Performing an Auto Approach 1 40 Setting Sean Parameters re secs tosh atest ea EASES 1 43 Starting a SCAM are ee ernannten 1 44 Taking Images of Other Signals eee eeeeeeeeceeeceseceseceseceaecaecsaeeneeees 1 44 Taking an Image Using the MFM Amplitude Signal 1 44 Taking an Image Using the MFM Phase Signal uune 1 47 Taking an Image Using the Magnetic Force Signal 1 49 Taking Follow Up Images of Sample Topography 20 1 50 Applying an Electrostatic Bias Between the Tip and the Sample 1 52 When to Apply an Electrostatic Bias unsuesseesnesnnesnnesnnennen 1 52 How to Apply an Electrostatic Bias uuenuuesseennesnnenneennesnnennnn 1 53 Where to Go From Here essen sense 1 55 How Non Contact AFM Vo Sa S OE ETa 1 56 Contents
37. a cantilever a probe cartridge a chip carrier and a sample as you normally do Note If you have not yet performed the F vs d calibration procedure for the cantilever you are using and if you plan to do so now be sure to use a hard sample such as the calibration grating provided with your system 3 After opening ProScan software turn off the probe head by clicking the Head ON icon on the Toolbar 4 Select Configure Parts from the Setup menu and set up the system for taking an AFM image 5 Reset the Z stage 6 Align the deflection sensor 7 From Move mode perform an auto approach When the approach is successful the green Z Piezo bar underneath the Toolbar should indicate that the scanner is extended roughly to its mid range and the yellow Probe Signal bar should show the Error signal to the feedback loop fluctuating regularly about the set point as the sample moves back and forth relative to the tip 8 Switch to Image mode and click the button to start taking an image Note Make sure the Save to Buffer icon i is ON before you begin taking an image If the Save to Buffer icon is not ON then the image you take cannot be saved and therefore any F vs d curves you take cannot be saved with the image The Save to Buffer icon is ON by default After you collect an image that you wish to use as a basis for F vs d data acquisition import that image to the Import View by click
38. a step height standard in place of the 1 um gold grating sample 2 Make sure that you are in high voltage mode by selecting High Voltage from the Mode menu 3 Approach the sample set scan parameters and take a contact AFM image as you normally do Be sure that the step of known height on your sample is included in the image In addition scan across the step in the fast scan direction 4 Use the Line Analysis software tools described in the Image Processing chapter of Part III of this User s Guide to measure the known step height in the z direction on the image 5 Compare the measured distance value to the known distance value If the distance produced by the software measurement tools is incorrect then the calibration parameter for the scanner sensitivity in the z direction MicronPerDac_SZ needs to be changed The correct z scanner calibration value is the existing value multiplied by the ratio of correct to measured distances Calibrating a5 Micron Scanner 6 21 correct distance correct cal value existing cal value x g measured distance 1 For example if you ask the software to measure a distance that you know is 0 2 um and it produces a value of 0 16 um and the existing MicronPerDac_SZ value is 0 6 then you should change the value as follows MicronPerDac_SZ 0 6 x a 0 75 6 Enter the correct value for the MicronPerDac_SZ parameter in the table you created earlier for the first and seco
39. an STM Image Ideally for a relatively flat featureless sample each signal trace should look similar to the one before If you are scanning a sample with closely spaced periodic features for instance a 1 um gold grating look for features with the same spacing in the signal trace A signal trace that jumps erratically or one that is jagged indicates that the scan parameters are not optimized For instance a saw tooth signal trace might be an indication that the tip is tapping the surface as the sample is scanned To increase the tip to sample spacing decrease the tunneling current by lowering the set point value Since the STM tip is held rigidly in place on the STM cartridge it is much easier to damage both the tip and sample surface during a scan if the tip makes contact The AFM tip on the other hand is mounted on a flexible cantilever 2 26 Chapter2 STM Imaging When you are trying to obtain atomic resolution images there are several ways you can distinguish atoms on the surface from noise in an image 1 Vary the scan size Ifthe corrugations you see in the signal trace represent atoms then their size should scale with the scan size becoming smaller for larger scan sizes 2 Move to a slightly different location on the surface In the next scan the position of the corrugations in the image should shift accordingly 3 Change the scan rate If the corrugations represent atoms changing the scan rate shoul
40. and der rechten Seite des Tastkopfes befinden dienen zur justierung der Position des Aufteffpunktes des Laserstrahles auf den Balken Die Schrauben bewegen den Laserpunkt in zwei Richtungen wie in Bild 0 3 oben gezeigt wird Falls ihr System die zus tzliche CP Optics enth lt k nnen sie diese Justierung berwachen indem sie die optische Ansicht auf ihrem Videobildschirm darstellen PSPD adjustment screws Am Tastkopf befinden sich zwei PSPD Schrauben auf ab und forw rts r ckw rts Diese Schrauben justieren die Position des PSPD s im Tastkopf um das reflektierte Laserlicht auf dem Photodetektor zu zentrieren Die forw rts r ck w rts Justierungsschraube kann an allen Tastk pfen zur PSPD Einstellung benutzt werden Die auf ab Justierung kann haupts chlich f r den AFM LFM Tastkopf der Standardkonfiguration benutzt werden Laser intensity indicators Zeigt die Intensit t des reflektierten Laserlichtes das auf den PSPD Positions sensiblen Photodetektor trifft an Betriebssicherheit xxxiii Es gibt drei Tastk pfe f r die Standardkonfiguration AFM AFM NC AFM AFM LFM Die verschiedenen Tastk pfe haben verschiedene Indikatoren Beachte Der AFM Tastkopf kommt mit der Standardsystemkonfiguration Die AFM NC AFM und AFM LFM Tastk pfe sind zus tzlich zur Standard systemkonfiguration erh ltlich Die Indikatoren des AFM Tastkopfes sind in Bild 0 3 oben eingezeichnet Bei diesem Tastkopf ist die maximale Laserlich
41. another chip If you are using an unmounted chip carrier try adjusting the position of the chip in the carrier Once the deflection sensor is aligned you are ready to perform an auto approach 3 14 Chapter 3 LFM Imaging Performing an Auto Approach The auto approach process brings the cantilever into contact with the sample The approach stops when the amount of vertical deflection of the cantilever matches that represented by the set point parameter 1 In Move mode use the z direction pad to lower the probe head bringing the tip to within a few millimeters of the sample surface Then click the button to initiate an approach You should hear the motor in the head start and then continue Troubleshooting Tips Approach If you hear the motor start and then stop without proceeding further then the approach probably did not work Try the following troubleshooting tips 1 Make sure that the set point is high enough 2 The absolute value of the signal representing vertical deflection of the cantilever is usually close to but not equal to zero even if the corresponding laser position indicator lights are not lit This signal which is the difference between the signals from the left and right halves of the PSPD must be within a certain tolerance or range in order for the system to perform an approach In the case that it is outside this range even though the laser position indicator lights may not be lit you need
42. as large as possible by typing a value larger than 5 um in the Size textbox The system will then default to the largest scan size possible which varies somewhat from scanner to scanner 7 Set the x direction as the fast scan direction 8 Use a scan rate that is representative of the scan rate you will be most likely to use when you take large scans For a5 um scan of a gold calibration grating select a scan rate of 1 Hz 9 Adjust the set point gain and slope parameters until the signal trace on the Oscilloscope Display is level and representative of the sample topography 10 Click the button to take an image 11 Once the image is complete use the Line Analysis software tools described in the Image Processing chapter of Part III of this User s Guide to measure the spacing between the largest number of maxima for a given direction on the image For example for the gold calibration grating measure the spacing between 5 maxima along the x axis The spacing between 5 maxima should be 4 um 6 18 Chapter 6 Scanner Calibration 12 Compare the measured distance value to the known distance value If the distance produced by the software measurement tools is incorrect then the second order scanner calibration value for the x direction of a fast x scan MicronPerDacSq_FastSX needs to be changed At this point refer to the table of calibration parameters that you made when calibrating the first order parameters
43. by the deflection sensor located in the NC AFM probe head The deflection sensor includes a laser a mirror that reflects the laser beam onto the back of the cantilever and a position sensitive photodetector PSPD Both the frequency and the amplitude of cantilever vibration are monitored as changes in the position of the laser spot incident on the PSPD For MFM operation the DC component of the PSPD signal is read in addition to the AC component and it can be used to generate an MFM image This cantilever detection scheme is often referred to as the laser beam bounce technique The AC signal from the PSPD is sent to a lock in amplifier The lock in amplifier is a very narrow bandpass filter which is used to detect an AC signal at a specific frequency and output a DC signal proportional to its amplitude The frequency locked in for detection is set by the reference signal from the sine wave generator 1 67 The DC output signal from the lock in amplifier is sent to a comparator or differential amplifier The comparator compares the signal from the lock in amplifier which represents the vibration amplitude of the cantilever to a reference amplitude setting An error signal proportional to the difference between these signals is sent to the z feedback controller The electronics for the lock in amplifier the comparator and the z feedback controller are all located inside the NC AFM head The z feedback controller operates to raise
44. dependent force gradient is dominant This gives you greater flexibility in finding a set point value that produces a stable image of sample topography You can image sample topography with the tip farther from the sample surface in a regime where feedback oscillations and tip snap ins are less likely Taking anMFM Image 1 53 The second situation mentioned above tip crashes due to abrupt changes in the sign of the magnetic force can also be addressed by the application of an electrostatic bias to the sample In this case the bias is used to create a net force between the tip and the sample that is constant in sign The magnitude of the electrostatic force must be greater than that of the magnetic forces so that changes in the sign of the magnetic forces are perturbations only and the sign of the net force remains constant In general if you have difficulty obtaining stable imaging conditions when you are taking an MFM image or a follow up image of sample topography try applying an electrostatic bias to the sample The applied bias is a tool that gives you increased flexibility and can improve image quality How to Apply an Electrostatic Bias If you choose to apply a bias between the tip and the sample you must first make sure that your sample is in electrical contact with the scanner sample holder This is especially necessary if you use double sided tape to secure your sample to the sample holder since the tape is nonconducting
45. en mode AFM De fa on pr cise vous allez apprendre des proc dures pour connecter les c bles enlever et installer une t te de microscope et un scanner et charger un chantillon Chapter 3 Acquisition d un image AFM vous guide tout au long de la configuration du logiciel durant l approche de l chantillon et pour prendre une image AFM Chapter 4 Obtenir de meilleures images vous apprend optimiser les param tres de balayages et de feedback afin de prendre des images de meilleure qualit et comment les sauvegarder et les recharger Partie Il Apprendre utiliser l AutoProbe CP Techniques avanc es La partie II de ce Guide de l Utilisateur Apprendre utiliser l AutoProbe CP Techniques avanc es comprend des formations pratiques pour des op rations dans les modes suivants STM LFM NC AFM IC AFM and MFM Elle comprend galement des travaux pratiques qui vous introduisent aux possibilit s avanc es de l AutoProbe CP tels que les courbes force distance les courbes courant tension et la calibration du scanner Ixii Preface and Overview Le chapitre 1 Imager en mode STM vous guide afin de prendre une image en mode STM Dans ce chapitre vous apprendrez des proc dures pour pr parer des pointes STM et utiliser des cartouches STM pour configurer ordinateur et le programme afin de travailler en mode STM et prendre une image en mode STM Le chapitre 2 Imager en mode LF
46. field The bar is used as a graphical means of dynamically adjusting the scanner s sweep range during F vs d set up The left end of the Piezo Adjustment bar represents the limit to scanner retraction and the right end of the bar represents the limit to scanner extension You can use the mouse to drag the right and left ends of the red bar to change the limits of scanner extension and retraction respectively Clicking and dragging on the center of the red bar shifts the position of the entire bar which is equivalent to shifting the limits of the scanner s extension and retraction simultaneously The white field surrounding the red bar represents the entire z throw or range of motion of the scanner Note The z throw of a 100 um scanner is about 7 5 um The z throw of a5 um scanner is about 2 5 um The blue portion of the field represents the unused range of scanner motion between full retraction and the scanner s retracted position during F vs d data acquisition The scanner s z motion is shown relative to a Set Point arrow located on top of the Piezo Adjustment bar The red half of the Set Point arrow indicates the z position of the scanner when the set point value is matched at the x y location where the F vs d curve is acquired The black half of the Set Point arrow indicates an estimate of the location of the sample surface The limits of the scanner s sweep range are displayed numerically in units of micr
47. in the textbox above the Calibration Values listbox Type in the correct value in units of N m and then press the Enter key on your keyboard Click the button to register changes made and close the dialog box 4 Open the F vs d Spectroscopy window by either selecting Spectroscopy from the Mode menu or by clicking the Spectroscopy icon on the Toolbar The Spectroscopy window opens on the right side of the screen 5 Click the button located next to the button in the Image mode window This stops rastering of the scanner for F vs d data acquisition The z feedback loop is still enabled Clicking the button enables the and buttons of the Spectroscopy window When you click the button it changes to the button If you click the button the scanner rasters once again and the and buttons are disabled 6 Click the button to open the F vs d Setup dialog box By default the Use Database Value option button is selected in the Cantilever Force Constant portion of the dialog box Leave the default setting unchanged if you already checked that the cantilever force constant value in the database is correct in Steps 1 through 3 above Otherwise click the Enter Value Manually option button to select it and enable its associated textbox Then manually enter the cantilever force constant value in the textbox 7 You can leave the other F vs d Spectroscopy Setup settings at their default values or change them as you
48. is a more reliable measure of the scanner s z position than the Topography signal which represents the voltage applied to the scanner This is because the correlation between voltage applied to the scanner and scanner position is subject to the nonlinearities mentioned earlier For small variations in topography a smaller z range of the scanner is typically used 1 e low voltage mode At these reduced z ranges of scanner motion scanner non linearities are not a significant problem The signal to noise ratio of the z detector however decreases For this type of application the Topography signal is therefore preferable over the Z Detector signal as a measure of sample topography The Topography signal is often used in high voltage mode as well This description of how the scanner works and how its position is controlled and corrected will be useful to you as you perform the scanner calibration procedures Additional background information is provided in the next section which describes what it means to calibrate the scanner 6 26 Chapter 6 Scanner Calibration What it Means to Calibrate a 100 Micron Scanner Calibrating a 100 um scanner means calibrating both the ScanMaster detectors and the scanner sensitivity Voltage readings from the detectors must be calibrated with the distances those voltages represent measured in microns and voltages applied to the scanner tube must be calibrated with the distance that the scanner
49. it is then you can try re sweeping click the button to see if the glitch is removed You may also be able to move the cross hair to a slightly better location using the cursor as described before Figure 1 4 shows a zoomed in version of the frequency response curve The cross hair positioned to the right of the main resonance peak marks the drive frequency that will be used for the scan For this example the selected drive frequency is 96260 Hz NCM Frequency Set X 100mum div Set 0 121 Drive 4 cross hair RE 80 kHz f 96260 Hz 5kHz div Zoom In Zoom Qu Refresh Done Help Figure 1 4 Response curve for a typical NC AFM cantilever with the horizontal scale expanded by the zoom in operation Selecting an Imaging Amplitude The imaging amplitude is the amplitude of cantilever vibration that is maintained by the system s feedback loop during a scan The imaging amplitude is related to the absolute value of the set point parameter Selecting a set point value is therefore equivalent to selecting a force gradient or tip to sample spacing that will be maintained during the scan since the cantilever s vibration amplitude varies with the force gradient experienced by the cantilever For NC AFM operation the drive frequency lies on the right hand side of the cantilever resonance peak This choice of drive frequ
50. its function The tutorial in the next section teaches you how to use these controls Table 4 1 Controls in the F vs d Spectroscopy window Control Function Scale Allows you to adjust the scaling of the vertical and horizontal axes of an F vs d curve Resets the scaling of the vertical and horizontal axes Offset Allows you to shift an F vs d curve within the graph of the Spectroscopy window Zoom Sets the function of the cursor when it is positioned within the graph When the Zoom option button is selected you can use the cursor to define an area that you wish to zoom in on The Zoom option button automatically toggles off if you select the Measure option button Measure Sets the function of the cursor when it is positioned within the graph When the Measure option button is selected the system reports the cursor s coordinates on the graph and you can use the cursor to make point to point measurements on an F vs d curve The Measure option button automatically toggles off if you select the Zoom option button Run Prompts the system to disable the feedback loop and sweep the scanner continuously updating an F vs d curve that can be used for parameter adjustment Clicking the button enables the button which you can press to stop the scanner s sweeping Stops F vs d data acquisition and re enables the feedback loop Acq Initiates acquisition of one averaged F vs d curve taken at a point or sixteen averaged curves
51. level the signal trace 4 Click the button to start taking an image As the image builds up line by line in the Active display watch the Topography signal trace in the Oscilloscope Display Ideally each signal trace should look similar to the one before 5 Adjust scan parameters such as the gain set point and tip bias if necessary to improve surface tracking Information on optimizing scan parameters is provided in the next section 6 When the scan is finished even if this first image is not particularly good click the button to copy the image into the Import View Then you can move to a new location on the sample or vary the scan size by using the cursor box 2 22 Chapter2 STM Imaging Optimizing STM Scan Parameters This section describes how to optimize the current and bias parameters used for taking an STM scan The optimal values of current and bias parameters depend on a number of factors including what sample you are looking at whether it is semiconducting and what type of semiconductor it is Optimizing these parameters is usually an experimental trial and error process The set point parameter sets the tunneling current during an STM scan The tunneling current is given in nanoamps 10 9 amps The tunneling current between the tip and the sample in STM is analogous to the force interaction between the tip and the sample in AFM With feedback enabled and the feedback setting optimized the system operates to
52. makes contact both the tip and the sample will be damaged Contact between the tip and the sample referred to as a tip crash is indicated by an increased current reading on the DVM If the tip crashes you must change the tip before you can proceed with taking an STM image When the approach stops the tip will be within 10 A of the surface but will not actually be in contact After a successful approach the green Piezo bar should show that the scanner stops moving and is extended to about half of its full range Starting a Scan This section presents the basic steps involved in taking an STM image Optimizing scan parameters is discussed in a later section along with brief explanations of what these parameters control 1 Enter Image mode by clicking the Image mode icon Taking an STM Image 2 21 A signal trace representing surface topography should be displayed on the Oscilloscope Display The name of the displayed signal appears in the drop down list below the Oscilloscope Display The Topography signal should appear by default If the scaling appears inappropriate for the signal trace click the button auto re scale to re scale the signal trace to fit the display 2 Enter a scan size of several microns um Select a scan rate of about 1 Hz The default number of pixels per scan line is 256 and the default fast scan direction is the x direction 3 Adjust the slope parameter as needed to
53. of the image in the x direction measure the spacing between all three maxima For the gold grating the spacing between three maxima should be 2 um 11 Compare the measured distance value to the known distance value If the distance produced by the software measurement tools is incorrect then the first order scanner calibration value for the x direction of a fast x scan MicronPerDac_FastSX needs to be changed At this point it is recommended that you create a table listing the names of all calibration parameters that you will be checking Make a row for each of the four first order and four second order calibration parameters and an additional row for the z direction calibration parameter MicronPerDac_SZ which you will be determining in a later section Make two columns for each row labeled High Voltage Mode and Low Voltage Mode so that you can enter two separate values for each parameter depending on whether you are operating in high or low voltage mode Keep this table for future reference As mentioned earlier if you ever need to reinstall the software the default values of all calibration parameters will be restored 12 Calculate a new value for a first order scanner calibration parameter using the following formula 6 14 Chapter 6 Scanner Calibration 13 14 15 16 17 correct distance correct cal value existing cal value x g measured distance 1 For example if you ask t
54. of topographically smooth samples quickly since the gain is set to a low value and higher scan rates can be used In addition because the probe signal is represented more directly by the MFM Amplitude signal than by the Topography signal MFM Amplitude images may show sharper contrast of magnetic features when these features are subtle To take an MFM image using the MFM Amplitude signal follow these steps 1 Set up the instrument as described earlier for MFM imaging 2 Set the NCM scan parameters the drive frequency drive amplitude and imaging amplitude as described in the earlier section Setting NCM Parameters for MFM imaging 3 Perform an auto approach Next you will select the input signals that you wish to view on the Oscilloscope Display You will monitor these input signals as you adjust scan parameters for taking an image 4 Switch to the Image mode window and select Input Config from the Setup menu to open the Input Configuration dialog box Alternatively click the Input 1 Config icon 1 46 Chapter 1 10 11 NC AFM IC AFM and MFM Imaging The Topography signal should be listed in the Selected listbox by default Click on MFM Amplitude from the list of signals in the Available listbox then click the button to add the MFM Amplitude signal to the list of signals in the Selected listbox As described above the MFM Amplitude signal represents the amplitude of cantilever
55. parameters takes about 20 minutes When the procedure is complete the calibration parameter values are written to the appropriate file and the button is enabled 6 Click the button to return to Move mode The above scanner calibration procedure when performed in high voltage mode determines values for the detector offset and scanner sensitivity calibration parameters in high voltage mode Now the procedure must be repeated to determine the values for these parameters in low voltage mode 7 Switch to low voltage mode by selecting Low Voltage from the Mode menu 6 38 Chapter 6 Scanner Calibration 8 Repeat Steps 4 through 6 above The detector offset and scanner sensitivity calibration parameters are now calibrated for both high and low voltage modes Creating a Backup Scanner Calibration File If you have completed the instructions of this section then you have calibrated your 100 um scanner and thus created a new calibration parameter file Saving a backup copy of this file involves the following general procedures 1 Create a special directory c scancal for backup files 2 Create backup copies of the current scanner calibration parameter files and store them in c scancal Each time you perform a scanner calibration you automatically update the working scanner calibration parameter file You should update the backup copy of this file in the c scancal directory at the same time in case the working file beco
56. parameters and take images as described in the previous sections on MFM imaging As the images are being taken select the image that represents magnetic features most clearly Viewing the Magnetic Force signal in combination with other MFM signals may help you to identify magnetic features and therefore improve your ability to optimize scan parameters Taking Follow Up Images of Sample Topography Once you have obtained an MFM image you can collect an image of the sample topography either by moving the tip closer to the sample to collect an NC AFM or IC AFM image or by taking a contact AFM image Taking an NC AFM or IC AFM image has the advantage that both techniques minimize contact with the sample surface For magnetically soft samples contact between the sample surface and a magnetized tip can affect the magnetization of the sample surface To take a follow up image of sample topography do the following 1 Start with the same parameter settings you used to take an MFM image and select the Topography signal trace to be viewed on the Oscilloscope Display 2 Decrease the absolute value of the set point parameter incrementally until you see oscillations or glitches on the Topography signal trace as described earlier in the section Performing an Auto Approach for MFM imaging The appearance of oscillations or glitches indicates that the force gradient is increasing sharply or that the van der Waals force gradient is becoming
57. set point value should be apparent as a narrowing of the yellow band about the red line You are now ready to start a scan Starting a Scan After you have set and or adjusted the scan parameters listed in the previous sections so that the Topography signal trace in the Oscilloscope Display is stable and repeatable you are ready to start taking an image 1 Click the button below the Oscilloscope Display to start a scan You may need to adjust some of the scan parameters while a scan is being taken Try adjusting the set point drive and gain parameters to optimize the image Taking Images of Other Signals In addition to the Topography signal there are other signals that can be useful when you are taking images of magnetic samples These other signals include the MFM Amplitude signal the MFM Phase signal and the Magnetic Force signal This section describes how to set up to take an image using each of these signals and it explains how each type of image can be useful Taking an Image Using the MFM Amplitude Signal The MFM Amplitude signal represents the amplitude of cantilever vibration This amplitude is a function of the gradient of the force between the tip and the sample see the later section How Magnetic Force Microscopy Works for details For MFM imaging larger tip to sample spacings are used than for NC AFM imaging In this distance regime the force gradient is dominated by the magnetic force The MFM Amplitude si
58. set up for an approach select Approach from the Setup menu This opens the Approach Parameters dialogue box By default the system is set up for an incremental approach Select Quick then click the button to register the change and close the dialogue box Note For details on setting approach parameters refer to the section Setup Approach in Part III Software Reference of this User s Guide 2 Perform a coarse approach by using the z direction pad to lower the probe head until the tip is within a few millimeters of the sample surface Then click the button to initiate an auto approach The first noise you hear is the system lifting the tip before the approach Then the system decreases the tip to sample spacing The auto approach stops when the cantilever vibration amplitude the probe signal matches that represented by the set point value displayed in Image mode Note If for any reason you want to re select the drive frequency after the system has performed an auto approach you need to lift the tip using the upper z direction pad This positions the tip away from the sample so that its free space resonant frequency can be determined 3 Switch to Image mode to view the Oscilloscope Display If the Topography signal is not already selected select it now from the Input Configuration dialogue box so that you can view the Topography signal trace on the Oscilloscope Display 4 The absolute value of the default s
59. showing location of laser safety compliance label System Configurations Standard Multitask Measurement Performance Standard Scanner Scan range Control resolution Multitask Scanner Scan range Control resolution Microscope Stage Translation range Sample size Tip to sample approach Optical microscope Acoustic isolation XIX Specifications and Performance for AutoProbe CP Includes an AFM probe head for operation in AFM mode Optional AFM NC AFM probe head can be purchased for operation in AFM non contact AFM intermittent contact AFM and MFM modes Optional AFM LFM probe head can be purchased for operation in AFM and LFM modes Optional STM toolkit can be purchased for operation in STM mode Includes a multitask probe head for operation in the following modes contact non contact and intermittent contact AFM MFM LFM and STM 5 um piezoelectric scanner Maximum lateral scan range 5 um Maximum vertical scan range 2 5 um Maximum lateral resolution 0 0013 Maximum vertical resolution 0 009 100 um piezoelectric scanner Maximum lateral scan range 100 um Maximum vertical scan range 7 5 um Maximum lateral resolution 0 25 Maximum vertical resolution 0 025 8 mm x 8 mm 50 mm w x 50 mm 1 x 25 mm h for the standard configuration 50 mm w x 50 mm 1 x 20 mm h for the multitask configuration Automatic with 3 independent stepper motors Optio
60. sont serr es correctement les performances maximum de l instruments sont assur es puisque les vibrations sont r duites xlix AVERTISSEMENT Afin de prot ger le EMC placer le couverde m tallique sur la base du CP lors de l acquisition de l image Mise la terre de l AutoProbe CP L AutoProbe CP doit tre correctement mis la terre avant l enclenchement de ses composants Le c ble d alimentation g n rale doit tre ins r dans une prise munie d une fiche de mise la terre Si vous n avez pas acc s une prise munie d une fiche de mise terre vous devez mettre AutoProbe CP la terre en utilisant la connection de mise en terre de l AEM La Figure 0 1 ci dessous montre ou est situ la connection de mise terre AEM Ground connection re H i Figure 0 1 Panneau arri re du AEM montrant l emplacement du connecteur de mise la terre Preface and Overview Configuration de la tension d alimentation Le choix de la tension d alimentation doit correspondre la tension d alimentation du pays o le syt me AutoProbe CP est utilis Le choix de la tension d alimentation se fait l aide d un s lecteur de tension Ce s lecteur est situ sur le panneau arri re du AEM Le s lecteur de la tension d alimentaion permet un choix parmi les tensions suivantes 100 V 120 V 220 V or
61. system s tracking of the sample surface CAUTION The default value of the gain parameter 0 01 is too low Using this value is likely to result in the tip crashing into the sample surface 5 Set the scan size to zero This stops the scanner from moving the sample while you perform a coarse tip to sample approach Before you initiate an auto approach you should move the tip as close to the sample as possible by eye Be careful not to touch the tip to the sample surface however If the tip is close to the sample surface then the auto approach will take less time If you are using an AutoProbe CP with on axis optics you will be relying mainly on the focus of the tip and the side view of the tip that you obtain by eye If you are using separate optics along with your AutoProbe CP instrument it is easiest to perform a tip to sample approach using the oblique view provided by the optics Taking an STM Image 2 19 6 Enter Move mode by clicking the Move Mode icon lt lt 7 Find the tip in the optical view and focus on it If you are using the AutoProbe CP with on axis optics Turn on the light source for the optical view using the Optics View button Zoom out to obtain the widest field of view using the sliding zoom hardware lever Then focus on the tip using the coarse and fine focus knobs You may need to move the Z stage and or the XY translation stage to bring the tip within the optics view and ran
62. taken along a line Resets the range of data read for subsequent F vs d curves to cover the entire sweep range of the scanner not the zoomed in range 4 6 Chapter4 Force vs Distance Control Cop Buffer Extend and Retract microns Extend and Retract nN Cal Sweep Calibrate Z Drive Z Detector Table 4 1 continued Controls in the F vs d Spectroscopy window Function Allows you to copy raw data values of a particular F vs d curve from the F vs d Spectroscopy window into the Clipboard which can then be used to export the data into any appropriate Windows application Allows you to redisplay F vs d curves previously saved to an image file Saves F vs d curves i e numerical information corresponding to each F vs d curve to the image file associated with the curves Allows you to scroll through F vs d curves associated with the image in the Import View Allows you to set the range of scanner extension and retraction during acquisition of an F vs d curve The maximum range depends on the scanner you are using Displays the range of cantilever deflection during acquisition of an F vs d curve Prompts the system to store and display subsequent curves as volts on the vertical axis vs distance on the horizontal axis These curves can then be used for calibrating the vertical axis units with force Prompts the system to compute and save the vertical axis calibration coefficien
63. tes oder Eigentum und jeglicher Kosten f r R ckgewinnung Umprogrammierung oder Reproduktion jeglicher Programme oder Daten gespeichert oder ben tzt in ThermoMicroscopes Produkten haftbar gemacht werden Gewisse Staten erlauben keine zeitliche Begrenzung einer unausgesprochenen Garantie und oder der Ausschliessung spezieller nebens chlicher oder Folgesch den In diesem Falle treffen die obenstehenden Einschr nkungen und oder Ausschliessungen f r sie nicht zu Diese Garantie gibt ihnen spezielle juristische Rechte neben den m glichen anderen Rechten die sie haben welche von Staat zu Staat varieren Hersteller Information Das AutoProbe CP beinhaltet keine Teile die vom Benutzer selber gewartet werden d rfen Alle Unterhaltsprobleme sollten unverz glich den rtlichen ThermoMicroscopes Vertretern gemeldet werden ThermoMicroscopes USA ThermoMicroscopes USA 1171 Borregas Avenue 6 Denny Road No 109 Sunnyvale CA 94089 Wilmington DE 19809 T 408 747 1600 T 302 762 2245 F 408 747 1601 F 302 762 2847 ThermoMicroscopes SA ThermoMicroscopes Korea 16 rue Alexandre Gavard Suite 301 Seowon Building 1227 CAROUGE 395 13 Seokyo dong Mapo ku Geneva Switzerland Seoul Korea T 41 22 300 4411 T 82 2 325 3212 F 41 22 300 4415 F 82 2 325 3214 Falls sie ihre Systemkomponenten welche mit Schadstoffen in Ber hrung kamen zu Unterhaltszwecken zu ThermoMicroscopes zur cksenden m ssen folgende Regeln beachtet wer
64. the sample surface the repulsive force dominates exerting a positive net force on the cantilever An atomic force microscope in contact mode is operated within this range of forces where the total net force on the cantilever is positive Understanding Force vs Distance Curves 4 29 Understanding Force vs Distance Curves A force vs distance curve is a graph of the vertical force on the cantilever tip as a function of the extension of the piezoelectric scanner tube The vertical force on the cantilever tip is proportional to the cantilever bending which is measured using a position sensitive photodetector PSPD A force vs distance curve is generated at a single location on a sample surface by measuring how much the cantilever bends during one or more sweeps up and down movements of the scanner Variations in the shape of force vs distance curves taken at different locations indicate variations in the local elastic properties of the sample surface The shape of the curve is also affected by contaminants and surface lubricants as well as a thin layer of water on the surface which is usually present when operating an AFM in air A generalized force vs distance curve is shown in Figure 4 6 for the case of an AFM operating in air It is generated at a specific location on the sample surface by extending and then retracting the scanner while measuring cantilever bending In the figure the vertical axis force represents the me
65. the value of the parameter by typing the new value into the textbox above the Calibration Values listbox Again be sure to retain a negative sign if the value is a negative number Press the Enter key after entering the new value so that the correction is recognized by the software 7 Click to register the change and close the dialog box You have completed calibration of the z detector After the correction is made the software should measure the step height correctly You are now ready to proceed with the auto calibration procedures Auto Calibration of Detector Offsets and Scanner Sensitivity This section describes the auto calibration procedures for calibrating the detector offset and scanner sensitivity calibration parameters Any sample or no sample can be used for the auto calibration procedure as the procedure does not involve a sample Calibrating the detector offsets means measuring the voltage outputs from each detector when no voltage is applied to the scanner tube If these values are non zero then the finite value read is entered as the detector offset value for a given direction That value is used to correct all subsequent detector readings for that direction Calibrating the scanner sensitivity means calibrating the volts applied to the scanner tube with the distances that the scanner tube moves If the scanner has not been used much recently you may want to exercise it for an extended period of
66. three easy to use parts The parts include the following PartI Learning to Use AutoProbe CP Basic Imaging Techniques Part Il Learning to Use AutoProbe CP Advanced Techniques Part Il Software Reference The contents of the above listed parts are described in detail in the sections below Part I Learning to Use AutoProbe CP Basic Imaging Techniques Part I of this User s Guide Learning to Use AutoProbe CP Basic Imaging Techniques contains an introductory chapter and three hands on tutorials Chapters 2 through 4 By working through the tutorial chapters you will learn the basic skills needed to set up the instrument and to take an AFM image Start by reading Chapter 1 AutoProbe CP Basics for an introduction to the system configurations and the components of AutoProbe CP Then work through the tutorial in Chapter 2 Setting Up to Take an Image to learn how to set up the system hardware and software for AFM mode More specifically you will learn the procedures for connecting cables removing and installing a probe head and a scanner and loading a sample and a probe Chapter 3 Taking an AFM Image guides you through setting up the system software approaching the sample and taking an AFM image Chapter 4 Taking Better Images teaches you how to optimize scan and feedback parameters to take higher quality images and how to save and retrieve images Part Il Learning to Use AutoProbe CP Advanced Techniques
67. to generate an averaged F vs d curve In the Average scrollbox enter the number of sweeps and then press the Enter key Or use the scrollbox arrows to scroll through the range of values Up to fifteen curves can be averaged There are 1000 data points per curve Set the rate at which the system will sweep the extension and retraction of the scanner Enter the desired rate in the Rate scrollbox and then press the Enter key Or use the scrollbox arrows to scroll through the range of values The sweep rate is displayed in units of Hz and the maximum rate is 10 Hz Leave the Zoom Priority at its default value which is Snap Out This setting tells the system to display a zoomed in F vs d curve with the snap back point positioned correctly along the horizontal axis Details about the Zoom Priority function are given in the section Zooming in on a Region of Interest later in this chapter Click the button to register any changes made and exit the dialog box 4 16 Chapter 4 Force vs Distance By default the location on the image where the F vs d curve will be taken is at the center of the image as indicated by the presence of a cross on the image in the Active Display You can change this location as follows 10 Use the mouse to position the cursor on the image in the Active Display where you want the F vs d curve to be acquired Click the mouse button The cross will appear at the new location
68. to save them to disk along with their associated image 4 24 Chapter 4 Force vs Distance Saving Exporting and Printing Data The button saves up to sixteen curves with the image file corresponding to the image displayed in the Import View Saved curves can be redisplayed later in the F vs d Spectroscopy window The button places numerical force values as a function of distance into the Clipboard The numerical information can then be pasted into other software applications such as Excel which enable you to perform in depth analyses on your data To save F vs d curves do the following 1 Click the button Curves currently in buffers associated with an image are saved to the image file You can save up to sixteen curves with any image To export F vs d data to the Notepad or another Windows application do the following 2 Scroll through the buffers to the F vs d curve whose data you want to export 3 Click the button This places the data for the currently displayed F vs d curve in the Clipboard 4 Open the Notepad From the Edit menu select Paste The numerical values of force as a function of distance should appear on the Notepad Alternatively you can open any software application where you want to paste the numerical information From the Edit menu select Paste The numerical information associated with the curve should appear in the application To print an F vs d curve do the following 5 Scr
69. werden bevor seine Komponenten eigeschaltet werden Das Versorgungskabel darf nur mit einen Anschluss verbunden werden der mit einem Erdungspol versehen ist Falls sie keinen Anschluss mit einem Erdungspol haben m ssen sie das AutoProbe CP System ber den Erdungspol am AEM mit Erde verbinden Die Position des Erdungspoles is im folgenden Bild 0 1 eingezeichnet Ground connection s H Bild 0 1 R ckwand des AEM zeigt die Position des Erdungspoles xxx Vorwort und bersicht Einstellen der Versorgungsspannung Die Einstellung der Versorgungsspannung muss mit der Versorungsspannung des Landes bereinstimmen in dem das AutoProbe M5 betrieben wird Die Einstellung erfolgt ber einen Spannungs Wahl Schalter der sich an der R ckseite des AEM befindet Die Spannung kann folgendermassen eingestellt werden 100V 120V 220V oder 240V Um die Einstellung der Versorgungsspannung zu ndern m ssen folgende Schritte befolgt werden 1 Versichern sie sich dass die Spannung des AEM ausgeschaltet ist 2 Stecken sie das Versorgungskabel des AEM aus 3 Entfernen sie die Abdeckung der Spannung Wahl Schalter Einheit mit Hilfe eines passenden Schraubenziehers 4 F hren sie ein passendes Werkzeug in den Schlitz des Spannung Wahl Schalters und l sen sie mit dessen Hilfe das Spannungs Wahl Rad aus der Einheit 5 Stellen sie das Spannung
70. will not have sufficient time to respond to the surface topography The result will be poor surface tracking and the tip may crash into protrusions on the surface In non contact mode slower scan rates are required to give the system more time to respond to changes in surface topography A good range of scan rates to use is from about 0 5 Hz for more difficult samples with large variations in topography to about 2 Hz for flat samples 1 Select a scan rate Type in a value and then press the Enter key on your keyboard Setting the Gain The gain the gain of the feedback loop is a parameter that controls how much the Error signal is amplified before being used to generate the feedback signal to the scanner Higher gain values mean that the feedback loop is more sensitive to changes in the force gradient experienced by the cantilever Surface features can then be tracked more closely If the gain is too high however then the feedback signal will fluctuate too strongly in response to small changes and the system will oscillate Feedback oscillations show up on the signal trace as fringes or ripples If the gain is set too low on the other hand then the z feedback will not be able to track surface topography properly When surface tracking is poor surface features can appear lopsided or the tip can hit features on the surface 1 Check the signal trace for feedback oscillations 2 If you see feedback oscillations in the si
71. wish More information on these settings is provided in the later section Generating a Force vs Distance Curve Click the button to register changes made and close the dialog box Acquiring Force vs Distance Data 4 13 8 Click the Cal Sweep checkbox to select it When the Cal Sweep checkbox is selected all subsequent curves generated either in Run or Acquire mode are stored and displayed as volts on the vertical axis vs distance on the horizontal axis Next you will generate an F vs d curve to use during the calibration procedure The curve you generate for the purposes of the calibration procedure is displayed as volts vs distance not force vs distance By default the location on the image where the F vs d curve will be taken is at the center of the image as indicated by the presence of a cross on the image in the Active Display You can change this location as follows 9 Use the mouse to position the cursor on the image in the Active Display where you want the F vs d curve to be acquired Click the mouse button The cross will appear at the new location Note Be careful not to drag the mouse as you click Clicking and dragging the mouse prompts the system to generate sixteen F vs d curves between two endpoints of a line 10 Click the button to start sweeping the scanner and generating F vs d curves You can adjust parameters while the scanner is sweeping At any time you can click the button to s
72. you can open I V Spectroscopy to redisplay the saved curves The button exports numerical current values as a function of voltage to the Clipboard The numerical information can then be pasted into other software applications such as Excel which enable you to perform in depth analyses on your data To save current vs voltage and dI dV curves 1 Click the button Any curves you generate will be saved to the image file To export current vs voltage data do the following 2 Scroll through the buffers to the I V curve whose data you want to export 3 Click the button This places the data for the currently displayed I V curve in the Clipboard Acquiring Current vs Voltage Data 5 13 4 Open the software application where you want to paste the numerical information From the Edit menu select Paste The numerical information associated with the curve should appear in the application Redisplaying Curves in I V Spectroscopy Current vs voltage curves that were saved to an image file can be redisplayed in I V Spectroscopy dI dV curves can also be redisplayed To redisplay curves follow these steps l If the I V Spectroscopy window is not open open it now by either selecting I V Spectroscopy from the Mode menu or clicking the Spectroscopy icon klon the Toolbar 2 Open the Load to Buffer dialog box by selecting Load from the File menu 3 In the Load to Buffer dialog box select the file name of the image you want
73. 240 V Pour changer la tension d alimentation proc dez comme suit 1 Assurez vous que l interrupteur de l AEM soit d clench 2 Debranchez le cordon secteur de l AEM de la prise d alimentation 3 Enlevez le couvercle du s lecteur de tension d alimentation en utilisant un tourne vis de taille appropri e 4 Ins rer un outil de taille appropri e dans la fente du s lecteur d alimentation et utiliser cet outil pour enlever le disque du s lecteur de tension 5 Positionner le disque de s lection de tension enlev pr cedemment sur la tension de ligne appropri e 100V 110V 220V ou 240V 6 Remettre le disque de s lection de tension en place dans l unit Assurez vous que la tension de ligne d sir e apparait dans la fen tre 7 Installer le cap t sur le s lecteur de tension de ligne La tension d alimentation devrait pr sent tre s lectionn e la valeur appropri e Recommandations l usage du laser li Recommandations l usage du laser Note Tout au long de cette section les sch mas se r f rent la t te du microscope AFM pour la configuration standard du syst me AutoProbe CP sauf notifications contraires L AutoProbe CP contient une diode laser aliment e par une basse tension avec une puissance maximum de 0 2mW CW d une longeur d onde de 600 700nm La diode laser aliment e jusqu 0 2mW 600 700nm doit tre accessible l int rieur L AutoProbe C
74. 5 Aligning the laser spot on the end of the cantilever After you have aligned the laser spot on the end of the cantilever you no longer need to move the laser beam Now you are ready to move the PSPD so that its center is aligned with the laser spot 3 Adjust the position of the PSPD to align the laser spot with the center of the PSPD As was mentioned at the beginning of this section this step can be challenging for a quad cell PSPD 3 12 Chapter 3 LFM Imaging When the PSPD is correctly positioned the center green laser position indicator light is on When the PSPD is not correctly positioned one or more red lights will be on Figure 3 6 shows how the PSPD adjustment screws move the PSPD Laser position indicator PSPD Up down PSPD Forward backward Figure 3 6 Adjusting the PSPD position up down and forward backward Make the following adjustments 1 When the top or bottom red light is on adjust the PSPD forward backward screw For the top red light rotate the screw counterclockwise CCW For the bottom red light rotate the screw clockwise CW 2 When the left or right red light is on adjust the PSPD up down screw For the left red light rotate the screw clockwise CW For the right red light rotate the screw counterclockwise CCW After making adjustments to the up down position you may need to readjust the forward backward position and vice versa Near the cor
75. AUTION The power to the AEM must be turned OFF before you remove or install the scanner CAUTION The four screws that connect the scanner to the CP base unit must be securely fastened to ensure proper grounding When the four screws are securely fastened maximum instrument performance is ensured since vibrations are reduced Loading a Sample 1 Secure a sample onto a sample mounting disk and load the disk onto the sample holder as described in Part I of this User s Guide When you are learning NC AFM imaging use the calibration grating supplied with your system to take your first images The periodic spacing of the grating features allows you to determine if the signal trace is stable and makes it easier to identify true surface topography as you practice varying scan conditions The shape of the imaged spacings also tells you if the tip you are using is sharp enough for non contact mode Alternatively you can use a sample whose topography you have already determined perhaps from an SEM micrograph or from a contact mode AFM image Installing the Probe Head and Probe Cartridge 1 Install the appropriate probe head by sliding it onto the support arms of the XY Translation Stage as described in Part I of this User s Guide Make sure that the LASER ON OFF switch is in the OFF position before you install the probe head If you have the standard AutoProbe CP system configuration Install the NC AFM probe head which
76. Beinhaltet einen Multitasktastkopf f r T tigkeit in den folgenden Betriebsarten ber hrendes ber hrungsfreies und periodisch kontaktierendes AFM MFM LFM und STM Messleistung Standard Scanner 5 um piezoelektrischer Scanner Scannreichweite Maximale laterale Scannreichweite 5 um Maximale verticale Scannreichweite 2 5 um Reglerresolution Maximale Lateralresolution 0 0013 Maximale Verticalresolution 0 009 Multitask Scanner 100 um piezoelectrischer Scanner Scannreichweite Maximale laterale Scannreichweite 100 um Maximale verticale Scannreichweite 7 5 um Reglerresolution Maximale Lateralresolution 0 25 Maximale Verticalresolution 0 025 Mikroscopb hne Verschiebbarkeit Probengr sse Spitze zu Probe Einfahrt Optisches Mikroscop Akustische Isolation Arbeitsplatz AEM Computer Massenspeicher Software Graphik Systemspannungen Dimensionen und Gewicht CP Grundeinheit AEM Computer Betriebssumgebung Temperatur Luftfeuchtigkeit Reinigungsmittel CP Grundeinheit Messkopf AEM und computer ber den Gebrauch des Benutzerhandbuches xxxvii 8 mm x 8 mm 50 mm w x 50 mm 1 x 25 mm h f r die Standardkonfiguration 50 mm w x 50 mm 1 x 20 mm h f r die Multitaskkonfiguration Automatisch mit 3 unabh ngigen Schrittmotoren Zus tzliches axiales Mikroscop mit Farbvideobildschirm zur Ansicht von Messf hlerspitze und Probe 5 1 Zoom bis zu 3 500X Ver
77. Click the or button again to start sweeping the scanner once again The limits of the scanner s sweep range over which data are collected will be those defined by the cursor s zoom box Note Sometimes a smaller portion of the scanner s sweep range is not large enough to accommodate drift and the portion of the F vs d curve that you are interested in moves off scale If this happens click the button This resets the range of data collection to once again match the full scanner sweep range You can then adjust the range of data collection again incrementally until you are satisfied with the curve Zooming in by Changing the Scanner s Sweep Range You can also zoom in on a portion of an F vs d curve by reducing the sweep range of the scanner This method of zooming in can be performed while the scanner is sweeping in Run mode The resolution of the data increases as the scanner s sweep range decreases To zoom in by decreasing the sweep range of the scanner follow these steps 1 Click the button to generate continuous F vs d curves that you can observe as you zoom in 2 Using the mouse grab an edge of the red Piezo Adjustment bar and drag the edge to shorten the bar Grab and drag each edge as necessary so that the sweep range of the scanner is reduced to cover only the portion of the F vs d curve that you are interested in Now try changing the sweep range of the scanner by typing new values in the Extend and Retra
78. FM mode which measures just vertical bending of the cantilever and is thus only able to measure changes in sample topography By measuring lateral bending or twisting of the cantilever LFM mode is used to monitor motions arising from forces on the cantilever that are parallel to the plane of the sample surface Such forces could arise from changes in the frictional coefficient of a region on the sample surface or from onsets of changes in topography Operating in LFM mode is therefore useful for measuring inhomogeneities in surface materials and also for producing images with enhanced edges of topographic features The LFM Signal This section describes how your system obtains the signal used to create an LFM image Just as for contact AFM operation when your system is operating in LFM mode it measures the bending of the cantilever using a position sensitive photodetector PSPD to detect deflection of a laser beam off of the cantilever For AFM mode the PSPD is used in a bi cell configuration or as two halves that detect vertical deflection of the cantilever For LFM mode the PSPD is used in a quad cell configuration This means that the PSPD can detect both lateral and vertical deflection of the cantilever Figure 3 1 shows both a quad cell and a bi cell PSPD a b Figure 3 1 A quad cell PSPD a and a bi cell PSPD b 3 4 Chapter 3 LFM Imaging LFM mode is used mainly to collect both topographic AFM and friction
79. FM Methods Vibrating cantilever AFM methods also known as attractive mode and non contact AFM methods use a vibrating cantilever held tens to hundreds of angstroms above the sample surface The cantilever tip either does not come into contact with the sample surface NC AFM and MFM or it comes into contact only at the lowest point in its vibration cycle IC AFM Because there is no contact or only limited contact between the tip and the sample vibrating cantilever AFM methods can be used to image samples of low moduli that can be distorted or even damaged by the tip in contact AFM mode In general a combination of these methods e g non contact and intermittent contact AFM allows the widest possible range of samples to be analyzed Vibrating cantilever AFM methods also lend themselves readily to imaging surface properties other than topography because forces between the cantilever tip and the sample can arise from other sources For instance magnetic domains on a surface can exert an attractive or repulsive force on a magnetized tip making magnetic force microscopy MFM possible Non Contact AFM NC AFM For non contact AFM imaging the cantilever tip is held about 50 to 100 above the sample surface during a scan It is vibrated at a constant frequency near its mechanical resonant frequency typically 50 to 400 kHz with an amplitude of a few tens of angstroms As the tip is scanned above the surface the cantile
80. FMTHERMOMICROSCOPES User s Guide to AutoProbe CP ThermoMicroscopes 1171 Borregas Avenue Sunnyvale California 94089 Tel 408 747 1600 Fax 408 747 1601 Part Il Learning to Use AutoProbe CP Advanced Techniques 48 101 1100 Rev C For ThermoMicroscopes ProScan Software Version 1 5 August 4 2000 Copyright Notice Copyright 1994 2000 by ThermoMicroscopes All rights reserved No part of this publication may be reproduced or transmitted in any form or by any means electronic or mechanical including photocopying for any purpose without written permission from ThermoMicroscopes Trademarks AutoProbe Piezolever Ultralever Microlever MicroCell Materials Analysis Package MAP MapPlot ProScan ScanMaster and ThermoMicroscopes are trademarks of ThermoMicroscopes Windows and Excel are trademarks of Microsoft Corporation Paradox is a trademark of Borland International Inc Trinitron is a trademark of Sony Corporation Mitsubishi is a trademark of Mitsubishi Electric America Inc HP LaserJet and PaintJet are trademarks of Hewlett Packard Company PostScript and Adobe Photoshop are trademarks of Adobe Systems Inc Phaser is a trademark of Tektronix Incorporated Others are trademarks of their respective owners Contents Preface RS EN She AR EN EE a Ey Operating Salely tr Bias nie ii RER I Rs ix Safety SYMDOlS En EEEN E EEA EAR ET A EEEE ix Definitions Warning Caution and Note x Summary o
81. From the File menu click New then click Folder This creates a new folder in c The label of the folder icon will be highlighted to indicate that it can be altered c Type scancal in the new folder icon label and press the Enter key Calibrating a 5 Micron Scanner 6 23 2 Select the scanner calibration parameter file be copied Using Windows Explorer go to the folder c psi cal Identify the scanner calibration parameter file s you wish to copy For example you will most likely wish to copy the file for the scanner you most recently calibrated 3 With the cursor on that file click the right mouse button to open the right mouse button menu 4 Copy the scanner calibration parameter file from c psi cal to c scancal Select Copy from the right mouse button menu b Move the cursor to the c scancal folder Click the right mouse button again and click Paste from the right mouse button menu c A copy of the selected scanner calibration parameter file will appear in the c scancal folder You have now created a backup copy of the scanner calibration parameter file 6 24 Chapter6 Scanner Calibration Calibrating a 100 Micron Scanner This section describes the scanner calibration procedures for AutoProbe CP instruments equipped with a 100 um scanner As mentioned in the introduction of this chapter AutoProbe CP multitask instruments come with a 100 um scanner while standard AutoProbe CP instruments come with a 5 u
82. G Das AutoProbe CP muss ordnungsgem ss geerdet werden bevor Spannung an seine Komponenten angelegt werden darf Das Versorgungskabel darf nur mit einen Anschluss verbunden werden der mit einem Erdungspol versehen ist F r weitere Informationen soll der Teil Erdung des AutoProbe CP folgend in diesem Vorwort beachtet werden WARNUNG Vor dem Einschalten der AutoProbe CP Systemkomponenten muss der Versorgungsspannungsschalter berpr ft werden Der Versorgungsspannungs schalter befindet sich an der R ckwand des AEM und kann folgendermassen eingestellt werden 110 V 120 V 220 V und 240 V F r weitere Informationen soll der Teil Einstellen der Versorgungsspannung folgend in diesem Vorwort beachtet werden WARNUNG Das AutoProbe Elektronik Modul AEM oder die CP Grundeinheit d rfen nicht ge ffnet werden Das AEM und die CP Grundeinheit f hren Hochspannung welche bei Freilegung zu ernsthaften Verletzungen f hren kann WARNUNG ThermoMicroscopes verlangt eine routinem ssige berpr fung der Kabel des AutoProbe CP Systems um sicherzustellen dass sie nicht durchgescheuert lose oder besch digt sind Kabel welche durchgescheuert lose oder besch digt sind m ssen augenblicklich dem rtlichen ThermoMicroscopes Servicevertreter gemeldet werden Das AutoProbe CP soll nicht benutzt werden falls Kabel durchgescheuert lose oder besch digt sind xxviii Vorwort und bersicht VORSICHT Alle AutoP
83. Intensite du laser et indicateurs de position de la t te de microscope AFM NC AFM et de la t te de microscope AFM LFM d une configuration de syst me standard Pour la configuration multitask lorsque la brillance du centre de la lumi re qui a une brillance variable est maximis e l intensit du laser touchant le PSPD est maximis Voir Figure 0 5 ci dessous liv Preface and Overview Multitask probe heads pe V0 analog for variable brightness Figure 0 5 Intensit du laser et indicateurs de position pour la t te de microscope multitask Indicateurs de position du laser Indique la position de la lumi re du laser r flechi touchant le PSPD Lorsque le point du laser est centr sur le photod tecteur la led verte du centre est allum e comme en figures 0 4 et 0 5 ci dessus La Figure 0 6 ci dessous montre la position de l tiquette d avertissement du laser l ext rieur de la coupole de 1 AutoProbe CP CAUTION LASER LIGHT WHEN OPEN DO NOT STARE INTO BEAM Figure 0 6 Position de l etiquette d avertissement du laser sur la base de L AutoProbe CP La Figure 0 7 ci dessous montre la position de l tiquette de conformit concernant la s curit du laser sur le panneau arri re du Module Electronic de I AutoProbe AEM Recommandations l usage du laser
84. M vous guide afin de prendre simultan ment des images en mode LFM et AFM Le chapitre 2 vous donne galement les informations pour obtenir des images LFM et les avantages d avoir disposition les 2 images LFM et AFM Le chapitre 3 Imager en mode NC AFM IC AFM et MFM d crit les principes des modes d op ration NC AFM IC AFM et MFM Le chapitre 3 vous donne galement les instructions pas pas afin d obtenir des images NC AFM IC AFM et MFM Le chapitre 4 Courbes Force Distance D crit comment obtenir des courbes force distance une position x et y donn e sur la surface de l chantillon en utilisant le traceur X Y de ProScan Data Acquisition Une courbe force distance est un relev de la force verticale que la pointe applique au levier en fonction de la distance pointe chantillon Les variations de la courbe fournissent des informations concernant les propriet s locales d lasticit la surface de I chantillon Le chapitre 5 Spectroscopie I V vous apprend utiliser la fen tre Spectroscopie I V de ProScan Data Acquisition pour g n rer des courbes courant tension I V et des courbes dI dV Ces courbes fournissent des informations importantes concernant les propri t s lectroniques de la surface Le chapitre 6 calibration du scanner d crit comment le scanner de votre systeme AutoProbe CP fonctionne et comment le calibrer afin de maintenir ses performances
85. M Imaging Introduction This chapter describes STM imaging for AutoProbe CP which is available in both standard and multitask system configurations If you have the standard system configuration then you should have an AFM STM probe head as well as an STM Upgrade kit If you have the multitask system configuration then your system includes the multitask probe head and STM tips that enable you to take STM images This chapter information on the following topics how to make an STM tip how to insert the tip in the STM cartridge how to set up the system hardware and software how to take an STM image The last two topics listed above are covered in the section Taking an STM Image at the end of this chapter This section guides you through taking an STM image of a gold calibration grating In addition the section includes scan parameter values that you can use as starting points for taking an STM image of a graphite sample Once you configure your system software for taking an STM image you will notice that the primary differences between STM mode and contact AFM mode involve the Image mode window When the software is configured for STM operation the set point parameter represents the tunneling current value that is maintained during a scan as opposed to the force value as for contact AFM imaging Also for STM operation the tip must be biased relative to the sample so that a tunneling current will flow The tip a
86. P doit toujours fonctionner avec la t te du microscope correctement install e ATTENTION Les contr les les ajustements et l ex cution de proc dures autres que ceux sp cifi s ici peuvent provoquer une exposition dangereuse aux rayons laser Figure 0 2 Montre les deux tiquettes d avertissement propos du laser de la t te du microscope Il est recommand de respecter rigoureusement les tiquettes d avertissement sur le laser CAUTION LASER LIGHT DO NOT STARE INTO BEAM gt k 0 2 mW AT 600 700 nm CLASS II LASER PRODUCT CLASS 2 PER EN60825 1 1994 S Figure 0 2 Etiquettes d avertissement propos du laser de la t te du microscope L tiquette d avertissement de gauche dans la Figure 0 2 ci dessus sp cifie que la t te du microscope est un laser de Classe II selon 21 CFR 1040 10 et 1040 11 L tiquette d avertissement de gauche dans la Figure 0 2 ci dessus sp cifie que la t te du microscope est un laser de Classe II selon EN60825 Les figures 0 3 0 7 ci dessous montrent l emplacement de tout les instruments de contr le et indicateurs se rapportant aux op rations effectu es avec le laser du syst me AutoProbe CP Ils montrent galement l emplacement de toutes les tiquettes d avertissements sur le laser d orifices et de conformit lil Preface and Overview laser power laser laser on off switch position intensity N indicators indicators vide
87. The files can also be found in the c psi cal directory A file name for a working file will typically include the size and the serial number of the scanner For example a file for a 100 um scanner with the serial number 0123 would have the file name 100_0123 scn Calibrating a 100 Micron Scanner 6 29 You may also have default scanner calibration parameter files under the drop down list in the CP LS Scanner category of the ProScan Database Configuration dialog box These default files contain typical calibration parameters for a particular model of scanner or scan head These default files cannot be used as working files unless scanner calibration is performed The default value for many of the parameters is listed as Invalid which means that a value has not yet been determined However the default files can be used after scanner calibration has been performed The default scanner calibration files should be left in the c psi cal directory as a backup in case the files for specific scanners become corrupted The file name for a default file will typically include the size of the scanner For example a default file for a 100 um scanner would have the file name 100um scn If for some reason you need to perform the scanner calibration procedure using a default file you should make a copy of the default file and work with the copy By doing this you will retain an uncorrupted default file as a backup To copy a default scanner calibra
88. The tip magnetizer is a strong magnet that magnetizes the tip in order to maximize its interaction with the magnetic sample 3 Insert the MFM chip carrier onto a non contact cartridge The procedure for inserting a chip carrier is the same as for contact mode AFM Refer to Part I of this User s Guide for detailed instructions if needed 4 Insert the probe cartridge in the probe head as described in Part I of this User s Guide Configuring the Software Configure the software as described in the section Taking an NC AFM Image in this chapter Aligning the Deflection Sensor Align the deflection sensor as described in the section Taking an NC AFM Image in this chapter Taking anMFM Image 1 39 Setting NCM Parameters The procedure for setting NCM parameters drive frequency drive amplitude and imaging amplitude for taking an MFM image are very similar to those for taking an NC AFM image The drive frequency and drive amplitude can be set to the same values as for NC AFM imaging Also you can start by using the default value of the set point parameter as for NC AFM imaging After you approach the sample with the default value of the set point parameter you decrease the absolute value of the set point until you see oscillations in the Topography signal trace This process is described in more detail in the section that follows Performing an Auto Approach 1 Open the NCM Frequency Set dialog box by
89. Works at the end of this chapter The increasing vibration amplitude helps produce intermittent contact between the tip and the sample NC AFM IC AFM and MFM Imaging 1 30 Chapter 1 To select a drive frequency do the following 1 Follow the steps of the section Selecting a Drive Frequency for NC AFM imaging to identify the main resonance peak of the cantilever When you have located the optimal resonance peak to use zoom in on the frequency response curve until the horizontal scale is divided into 5 kHz divisions Vary the drive value until the maximum peak height of the response curve is roughly one half of the full vertical scale Check the location of the cross hair on the peak For IC AFM imaging move the cross hair to the left hand side of the peak The cross hair should not be located on a glitch or shoulder If it is then you can try resweeping click the button to see if the glitch is removed You may also be able to move the cross hair to a slightly better location using the cursor Figure 1 5 shows a zoomed in version of the frequency response curve The cross hair positioned to the left of the main resonance peak marks the drive frequency that will be used for the scan For this example the selected drive frequency is 96260 Hz NCM Frequency Set x 100mpm div Set 0 121 Drive 4 cross hair EE ER LE EN 80
90. a 1 2 2 um div 512 buffer lines allocated Press F1 for Help dx 01 0000 dy 01 0000 dz 00 0000 Figure 4 1 The F vs d Spectroscopy window shown in Image mode When you enter Spectroscopy mode while operating your instrument as an atomic force microscope the software controls that appear are appropriate for acquiring force vs distance curves When you enter Spectroscopy mode while operating your instrument as a scanning tunneling microscope the software controls that appear are appropriate for acquiring current vs voltage curves 4 4 Chapter 4 Force vs Distance A force vs distance curve is generated with feedback disabled since you do not want the system to maintain a constant tip to sample spacing Each curve is generated at a single x y location on an image which you select using the mouse The force vs distance curve depends only on the amount of vertical force on the cantilever as the scanner extends and retracts and is therefore not affected by most of the scan parameter settings in Image Mode Variations in the shape of force vs distance curves taken at different locations usually indicate variations in the local elastic properties of the sample surface The shape of the curve may also be affected by surface contaminants as well as the thin layer of water on the surface which is usually present when operating an AFM in air Following are sections that describe displays and co
91. a few millimeters of the sample surface Then click the button to initiate an auto approach Switch to Image mode by clicking the Image Mode icon Y Make sure that the x direction is set to be the fast scan direction and that High Voltage is selected in the Mode menu Select a scan size The scan size should be representative of typical small scans you will take since the first order calibration parameters are used to correct small scan sizes Choose a scan size that will enable you to see at least a few periods of the features on your sample For the 1 um grating the smallest scan size you can take that enables you to see at least two periods is about 2 um Ideally if you commonly take 2 um images for example you should use a calibration sample that has features spaced on the order of 0 1 um In that case you would be able to select a scan size of 2 um and see roughly 20 periods Select a scan rate appropriate for the scan size you are using For example for a 2 um image of the gold grating try a scan rate of 2 Hz Note Since the response of the scanner varies depending on the speed of scanner motion it is important that you select an appropriate scan rate for the scanner calibration procedures Adjust the set point gain and slope parameters until the signal trace on the Oscilloscope Display is level and representative of the sample topography Click the button to take an image Note the orienta
92. a large topography dependent coulombic force term on top of the pre existing van der Waals and magnetic force terms Refer to the section How Magnetic Force Microscopy Works at the end of this chapter for details In this section you will learn when and how to apply an electrostatic bias to the sample to improve image quality When to Apply an Electrostatic Bias Two examples of situations where image quality might be improved by the application of an electrostatic bias are the following 1 You are having difficulty obtaining a stable follow up NC AFM image of sample topography 2 The sign of the net force on the cantilever changes abruptly while you are taking an MFM image for example where repulsive and attractive magnetic domains are adjacent and the tip crashes The first situation might occur if you are trying to take a follow up NC AFM image of a sample with strong magnetic features You may find that it is difficult to determine a set point value that brings the tip close enough to the sample surface to show topography without causing feedback oscillations or tip snap ins These effects can be caused by the abrupt increase in the gradient of the van der Waals force and or the strength of the magnetic forces that often characterize the close tip to sample range necessary for NC AFM imaging By applying an electrostatic bias to the sample you effectively broaden the tip to sample spacing regime over which the topography
93. aals regime roughly 5 to 10 nm and up to 50 nm does not sacrifice lateral resolution of magnetic features The set point is now optimized You are ready to adjust other scan parameters and take an MFM image Taking an MFM Image 1 43 Setting Scan Parameters 1 Select a scan size scan rate number of data points per image and a fast scan direction as described for taking an NC AFM image 2 Adjust the gain set point and slope parameters if necessary The purpose of adjusting the scan parameters is to obtain stable imaging conditions which depends on obtaining a stable signal trace that is free of glitches tip snap ins and saturated or truncated signals Iterative adjustment of some of the parameters listed below is generally required in order to produce a high quality image size gain rate slope setpoint The design of the instrument supports adjusting all of the parameters listed above in real time during a scan without having to lift the tip Adjust the parameters using the same guiding principles as described in Taking an NC AFM Image At this point you can skip ahead to the next section and take an image Or you can practice varying the value of the gain parameter to see its effect on the signal trace When you performed an auto approach you used the default value of the gain Now you can try increasing to a higher gain value to make sure that the Topography signal trace represents purely ma
94. ach component are also included Figure 1 11 shows a simplified diagram of the non contact system which applies to NC AFM IC AFM and MFM The primary components labeled in the diagram are the following piezoelectric actuator Cantilever and piezoelectric actuator Sine wave generator Deflection sensor laser mirror and PSPD Lock in amplifier Comparator and z feedback loop Piezoelectric scanner with mounted sample sine wave generator phase driving signal for cantilever vibration ref mirrors AC signal gt amplifier same differential DC u 4 laser amplitude K H V lock in signal F frequency as amplifier A PSPD driving signal amplitude ref D set point x Le Sf ee Cae vibrating Error signal ee v cantilever representing amplitude II sample change z feedback controller z scanner voltage Topography signal piezoelectric scanner image gain Figure 1 11 Diagram of hardware components and signal pathways for AutoProbe CP operating in NC AFM mode 1 66 Chapter 1 NC AFM IC AFM and MFM Imaging For vibrating cantilever AFM methods the cantilever is mounted in a specific type of cartridge referred to as a non contact cartridge The non contact cartridge has a thin piezoelectric actuator a piezoelectric transducer sandwiched between the cartridge and the c
95. age range from the adc is 10 V to 10 V One adc unit represents half of the adc range or 10 V Each detector calibration value represents the distance in microns along a given axis that the software associates with a change in the output from the detector of one adc unit or 10 V For example a value of 140 for the DetMicronPerAdc_SX parameter means that the software associates a change in position of 140 um along the x direction with a 10 V output from the detector Taking an Image and Determining Calibration Parameter Values To calibrate the xy detector you must take an image of your calibration sample with ScanMaster ON 1 Switch to Image mode by clicking the Image Mode icon Y 2 Select ScanMaster from the Setup menu This opens the ScanMaster Setup dialog box Make sure that ScanMaster is on by selecting the ON option buttons for both the x and y directions Click to register any changes and close the dialog box 3 Select Scan Config from the Setup menu Select the 512x512 option button from the Image Pixel Size section of the Scan Config dialog box Then click to close the dialog box Note Selecting 512 data points per scan line increases the resolution of your image This is especially important since you will be taking a large image to calibrate the xy detector 4 Select a large scan size e g 90 um so that you will be able to see several lines of the 9 9 um grid sample 5 Adjust the set point
96. aking a Constant Height Mode Image 2 25 While You Are Taking an STM Image 2 25 Taking an STM Image of a Graphite Sample 2 26 SUMMIALY 485 nn fe At nant nl A nine tie Al 2 27 Intr ducti n is atessreste monte Mir nie ot In 3 2 How Lateral Force Microscopy LFM Works 3 3 The LEM S16nal 5 8e essen keinen 3 3 The Tip Sample Interaction for LFM ss 3 4 Setting up the System nette BSIRRENH SB sey De osppmenhireneringenn 3 8 Installing the Scanner and the Probe Head 3 8 Configuring the Softwares seine 3 10 Aligning the Deflection Sensor 3 10 Troubleshooting Tips 55h tds ei ade 3 13 Performing an Auto Approach u 22uussenseensennnesnnnsnnesnnesnnennnennnesnan nennen 3 14 Troubleshooting Tips Approach 3 14 Taking an EM Images niet tir range 3 16 Selecting the LEM Signal 408250 resene EC men kE EKE ERE S 3 16 Setting Scan Parameters een eme hinn en e E EE EEC AEREN E 3 17 Starting a Scan nn piretrino sert renr neses Een senusenibnlsiensensshssbe 3 17 Troubleshooting Tips Signal Saturation nenn 3 18 SUMMALY e e E E E E E E E E E 3 19 Introduction ae E RE E E Ee E E EE REE E ETES 4 2 The F vs d Spectroscopy Window ss 4 3 The Force vs Distance Graph 4 4 Spectroscopy Mode Controls ss 4 5 The Piezo Adjustment Bar 4 8 Acquiring Force vs Distance Data 4 9 Setting
97. al LFM information during a single scan The topographic information is represented by vertical deflection of the cantilever which is measured as the difference between signals from the left and right quadrants of the quad cell PSPD By convention with contact AFM this signal difference is called the A B signal referring to the two halves of a bi cell PSPD A B signal A C B D Topographic information is also represented by the Topography signal which is a function of the A B signal Frictional information the LFM signal is represented by lateral deflection of the cantilever which is measured as the difference between the upper and lower quadrants of the quad cell PSPD LEM signal A B C D Note The PSPD is mounted facing the side of the cantilever Therefore lateral twisting of the cantilever is measured as vertical changes in the position of the laser beam on the PSPD Vertical bending of the cantilever is measured as lateral changes in the position of the laser beam on the PSPD By acquiring both the Topography and LFM signals an instrument operating in LFM mode can produce AFM and LFM images simultaneously The Tip Sample Interaction for LFM This section describes how LFM images correlate with changes in frictional coefficients and topography on a sample surface This description will help you to compare and interpret the information in LFM and AFM images Figure 3 2 illustrates how a cantilever res
98. al is not already selected select it now from the Input Configuration dialogue box so that you can view the Topography signal trace on the Oscilloscope Display Note The Topography signal is named for its representation of sample topography in NC AFM and IC AFM modes In all vibrating cantilever modes NC AFM IC AFM and MFM the Topography signal is the signal generated by the feedback loop and applied to the scanner to maintain a constant force gradient between the tip and the sample Refer to the section How Non Contact AFM Works for a discussion of the relationship between the force gradient and sample topography Taking an NC AFM Image 1 21 4 The absolute value of the default set point parameter and thus the tip to sample spacing that corresponds to the default set point value is typically too large for the system to detect the sample topography Begin now to incrementally decrease the absolute value of the set point parameter by clicking on the up arrow of the Set Point scrollbox As you decrease the absolute value monitor the Z Piezo bar the green bar located below the Toolbar which graphically represents the z position of the scanner within its total range of motion The Z Piezo bar should show the scanner extending as you decrease the set point value since the system is decreasing the tip to sample spacing as it attempts to match the lower set point value If you see that the system is extending the scan
99. an direction Note that there are two calibration parameters associated with each scan direction x and y One parameter is for when the direction is the fast scan direction and the other parameter is for when the direction is the slow scan direction There are different calibration parameters for the fast and slow scan directions because the scanner s response to applied voltage varies depending on the speed of scanner motion When you calibrate the scanner you will take one image using x as the fast scan direction to determine values for the MicronPerDac_FastSX and MicronPerDac_SlowSY parameters Then you will take a separate image using y as the fast scan direction to determine values for the MicronPerDac_FastSY and MicronPerDac_SlowSX parameters Before you perform the scanner calibration procedures two default calibration parameters are used for describing the scanner s response to applied voltage in the x and y directions The values of these default first order calibration parameters provide only an approximate description of the scanner behavior and just one calibration parameter value is used for each direction x and y The default first order calibration parameters for the x and y directions are named MicronPerDac_SX and MicronPerDac_SY respectively The system software uses these parameters when the value of any of the four first order calibration parameters or four second order calibration parameters is set as Invalid
100. anical instrumentation that can easily be damaged by improper handling CAUTION The power to the AEM must be turned OFF before you remove or install the scanner CAUTION The LASER ON OFF switch of the probe head must be in the OFF position before you remove or install the probe head on the XY translation stage Otherwise damage to the light emitting diodes LEDs of the probe head may result CAUTION When removing and installing the scanner you must be grounded via a grounding strap to ensure that the scanner is not damaged The scanner is sensitive to electrostatic discharge CAUTION The four screws that connect the scanner to the CP base unit must be securely fastened to ensure proper grounding When the four screws are securely fastened maximum instrument performance is ensured since vibrations are reduced xiii CAUTION To preserve safety and EMC compliance AutoProbe CP must be used with the EMI filter supplied with the AutoProbe CP system CAUTION To preserve EMC immunity place the metal cover on the CP base unit while imaging Grounding AutoProbe CP AutoProbe CP must be properly grounded before you turn on the power to its components The mains power cord must be inserted into an outlet with a protective earth ground contact If you do not have access to an outlet with a protective earth ground contact you must ground the AutoProbe CP system using the ground connection of the AEM Th
101. antilever is the square root of its spring constant k divided by its mass m w Kur 1 m Here the spring constant is written as kr the effective spring constant because the spring constant of the cantilever changes as the cantilever moves into close proximity within a few hundred angstroms of the sample surface and interatomic forces affect its behavior Specifically the spring constant changes when the force between the tip and the sample has a spatial gradient as it does in the non contact regime For a force gradient f the effective spring constant is given by the following expression keff k f 2 In Equation 2 k is the value of the cantilever s spring constant in free space that is it is the value when the cantilever is far from the sample surface The value of the cantilever s resonant frequency far from the sample surface is likewise referred to as its free space resonant frequency 1 58 Chapter 1 NC AFM IC AFM and MFM Imaging Equations and 2 show that if the cantilever moves into a tip to sample spacing regime where the force gradient is positive and increasing then the effective spring constant of the cantilever and therefore its resonant frequency decreases Figure 1 6 shows that in the non contact tip to sample spacing regime the force gradient is positive and it increases as the tip to sample spacing decreases Thus when an oscillating cantilever is brought near a sample surface the fo
102. apter Step 4 NC AFM IC AFM and MFM Imaging Set scan parameters Set the scan rate scan size number of data points per image and fast scan direction Adjust the drive set point gain and slope parameters if necessary Start a scan Click the button to begin acquiring an image in non contact mode While imaging continue to monitor the scan parameters and adjust them as needed The sections that follow explain these steps in detail and include important hints and tips for optimal non contact mode operation Setting Up the System Setting up the instrument to operate in NC AFM mode consists of the following general procedures Connecting cables Installing the scanner Loading a sample Installing the probe head and a probe cartridge Configuring the software Aligning the deflection sensor These procedures are described in the sections below Connecting Cables Connect a BNC cable between the frequency synthesizer BNC connector on the rear panel of the AEM and the NC CLOCK connector on the rear panel of the AutoProbe CP instrument Atthe AEM the cable is connected to the frequency synthesizer board which supplies the driving signal for cantilever vibration Connect all other cables as described for contact mode operation in this User s Guide Taking an NC AFM Image 1 9 Installing the Scanner 1 Install the scanner as described in Part I of this User s Guide C
103. artridge mount Between the two prongs of the cartridge there is a layer of gray material directly under the cartridge mount This layer is the actuator When an AC voltage signal is applied to the actuator the actuator oscillates it expands and contracts The oscillations cause a cantilever mounted on the cartridge to vibrate with the same frequency as the AC signal On the underside of the cartridge the side with the spring clip there is also a small red wire This wire delivers the AC voltage signal to the actuator The signal is delivered via a copper contact on the top surface of the cartridge which makes contact inside the NC AFM probe head Near the opposite corner of the cartridge is another contact which grounds the cartridge when it makes contact inside the probe head The AC signal or driving signal that causes the cantilever to oscillate with a constant frequency is generated by the sine wave generator The sine wave generator is located on the frequency synthesizer board installed in the AEM The drive frequency can be varied and is chosen to lie close to the cantilever s resonant frequency The amplitude of the driving signal can also be adjusted to maximize the vibration amplitude of the cantilever far from the sample surface The AC signal from the sine wave generator is also input to the lock in amplifier to provide the reference signal for lock in detection Motions of the oscillating cantilever are measured
104. aser light on the photodetector The forward backward adjustment screw is useful for PSPD alignment on all probe heads The up down adjustment is useful primarily for the AFM LFM probe head of the standard system configuration Laser intensity indicators Indicates the intensity of reflected laser light hitting the PSPD For the standard configuration there are three probe heads that require laser intensity indicators AFM AFM NC AFM and AFM LFM There are different indicators for the different probe heads xvii Note The AFM probe head comes with the standard system configuration The AFM NC AFM and AFM LFM probe heads can be purchased separately for the standard system configuration The indicators for the AFM probe head are shown in Figure 0 3 above For this probe head the intensity of laser light hitting the PSPD is maximized when the column of four red lights is lit The indicators for the AFM NC AFM and AFM LFM probe heads are shown in Figure 0 4 below For these probe heads when the brightness of the center green light which has variable brightness is maximized the laser intensity hitting the PSPD is maximized laser intensity and position indicators for other probe heads AFM NC AFM AFM LFM probe heads probe heads 2 O me ET analog analog for variable for variable brightness brightness Figure 0 4 Laser intensity and position indicators for the AFM NC AFM and AFM LFM probe heads
105. asured cantilever deflection The horizontal axis distance represents the z position of the scanner Force cantilever bending Scanner retracts Scanner extends gt distance scanner z extension N Snap back point Figure 4 6 A generalized force vs distance curve foran AFM in air The curve represents force experienced by the cantilever vs z position of the scanner 4 30 Chapter 4 Force vs Distance The far right side of the curve is defined to be where the scanner tube is fully retracted which is the starting point before a curve is taken The net force on the cantilever at this point should be zero The tip is not in contact with the sample and the cantilever is undeflected As the scanner tube is extended moving to the left in Figure 4 6 the cantilever remains undeflected until the tip is close enough to the sample to experience the attractive interatomic force At the snap in point point a in Figure 4 6 the tip snaps into the surface causing the cantilever to bend toward the surface The net force on the cantilever is negative attractive The scanner continues to extend until the cantilever is bent away from the surface The net force on the cantilever is positive repulsive After the scanner tube is fully extended it begins to retract moving to the right in Figure 4 6 The force on the cantilever follows a different path The horizontal offset between the initial and the return p
106. ateriel renvoy doit tre accompagn d un avis Exempt de substances toxiques Cet avis doit galement apparaitre sur le bulletin de livraison Ixi Comment utiliser ce guide de l utilisateur Le guide de l utilisateur pour l AutoProbe CP est divis en trois parties faciles utiliser qui sont les suivantes Partie I Apprendre utiliser l AutoProbe CP Techniques d imagerie de base Partie II Apprendre utiliser l AutoProbe CP Techniques avanc es Partie III References du logiciel Le contenu des diff rentes parties list es ci dessus est d crit en d tails dans la section ci dessous Partie I Apprendre utiliser l AutoProbe CP Techniques d imagerie de base La partie I de ce guide de l utilisateur Apprendre utiliser l AutoProbe CP Techniques d imagerie de base contient un chapitre d introduction et trois formations pratiques les chapitres 2 4 En travaillant sur les formations pratiques tout au long de ces chapitres vous allez apprendre les bases dont vous aurez besoin pour faire fonctionner l instrument et obtenir des images AFM Commencez par lire le Chapitre 1 Les bases de l AutoProbe CP comme introduction aux configurations et composants du syst me AutoProbe CP Puis travaillez sur la formation pratique du Chapitre 2 Faire fonctionner le syst me pour obtenir une image afin d apprendre comment configurer le syst me logiciel et mat riel
107. aths of Figure 4 6 is due to scanner hysteresis The additional portion of the curve that shows a negative attractive force on the cantilever is attributable to a thin layer of water that is usually present on the sample surface when the surface is exposed to air This water layer exerts a capillary force on the cantilever tip which is strong and attractive The water layer holds the tip in contact with the surface pulling the cantilever strongly toward the surface This deflection of the cantilever is shown on Figure 4 6 as region b where the net force on the cantilever is strongly negative The scanner tube eventually retracts far enough for the cantilever tip to spring free of the water layer This point is called the snap back or snap out point Multiple snap back points can occur when the force vs distance curve is averaged over more than one sweep of the scanner tube Beyond the snap back point the cantilever remains undeflected and the net force on the cantilever should be zero The next section includes cantilever data sheets that contain information about Microlevers and Ultralevers This information includes force constant values that you need in order to calibrate the vertical axis of an F vs d curve with force Cantilever Data Sheets 4 31 Cantilever Data Sheets This section contains information about Microlevers and Ultralevers You can enter the spring constant force constant for your cantilever in t
108. aute r solution 115 230 V AC 50 60 Hz 600 W 267 mm 10 5 in x 203 mm 8 in 10 kg 22 Ib 432 mm 17 in x 191 mm 7 1 2 in x 445 mm 17 1 2 in 20 kg 43 Ib 432 mm 17 in x 191 mm 7 1 2 in x 445 mm 17 1 2 in 12 kg 27 Ib 0 C to 30 C 32 F to 112 F 90 sans condensation alcool Isopropylique alcool Isopropylique alcool Isopropylique Iviii Preface and Overview ATTENTION Pour viter tout risques de choc lectrique aucun des composants du systeme AutoProbe CP ne doit tre nettoy lorsque le syst me est enclench AVERTISSEMENT Ne pas utiliser d ac amp tone pour nettoyer les composants du systeme AutoProbe CP L ac tone peut endommager les tiquettes d avertissement concernant la s curit lix Declaration de Garantie de ThermoMicroscopes Garantie des Systemes neufs et des Accessoires ThermoMicroscopes garanti au premier acqu reur que son systeme est exempt de tout d fauts de mat riel ou de fabrication et ceci pour une p riode d une ann e compter de la date de livraison Pendant cette periode de garantie ThermoMicroscopes est seul responsable du remplacement ou de la r paration selon son propre choix du mat riel sous garantie et ceci sans charge pour l acqu reur autre que des frais d envois ventuels ThermoMicroscopes se r serve le droit d ex cuter ces services soit sur site chez le client soit dans ses propres locaux Pour les r parat
109. auto approach remember to first lift the tip using the upper z direction pad in Move mode Once the probe head is turned off the z feedback loop is disabled Lifting the tip protects the cantilever from being damaged by possible contact with the sample 3 16 Chapter 3 LFM Imaging Taking an LFM Image Taking an image of a gold grating is a useful place to start when learning how to operate your AutoProbe instrument in LFM mode This is because a good image of a gold grating is relatively easy to identify In addition image quality is not as sensitive to scan parameter adjustment as it might be for other samples While it might seem that a grating would only show contrast due to changes in topography there are sometimes contaminants on the grating surface that are sticky These contaminants give rise to contrast in LFM images due to changes in frictional coefficients Taking an LFM image consists of the following general procedures Selecting the data channels or input configuration that you would like to acquire during each scan Adjusting scan parameters to optimize the AFM and LFM signal traces Initiating a scan Selecting the LFM Signal With the probe head turned on select Input Config from the Setup menu Alternatively click the Input Config icon In the Available listbox select LFM and then click the button This enables you to look at the LFM signal trace on the Oscillos
110. autres droits qui peuvent varier d un tat l autre Information du fabricant Toutes les questions relatives au service devront tre address es votre representant ThermoMicroscopes local ThermoMicroscopes USA ThermoMicroscopes USA 1171 Borregas Avenue 6 Denny Road No 109 Sunnyvale CA 94089 Wilmington DE 19809 T 408 747 1600 T 302 762 2245 F 408 747 1601 F 302 762 2847 ThermoMicroscopes SA ThermoMicroscopes Korea 16 rue Alexandre Gavard Suite 301 Seowon Building 1227 CAROUGE 395 13 Seokyo dong Mapo ku Geneva Switzerland Seoul Korea T 41 22 300 4411 T 82 2 325 3212 F 41 22 300 4415 F 82 2 325 3214 Si le mat riel que vous renvoyez au service technique a t en contact avec des substances toxiques vous devez observer certaines r glementations Les substances toxiques sont r glement es par les pays de la Communit Europ enne par Materials and Preparations en accord avec les directives EEC du 18 Septembre 1979 Article 2 Pour le mat riel qui a t en contact avec des substances toxiques vous devez proc der comme suit Decontaminate the components in accordance with the radiation protection regulations Le mat riel contamin doit tre d contamin en accord avec les directives et r glementations de protection radioactive Construct a notice that reads free from harmful substances The notice must be included with the components and the delivery note Le m
111. b e es bia le eS xl ber die Benutzung dieser Bedienungsanleitung c ccccssesseseesessesceseesessescesesseseeseanens xlii Pr face aiita ia taua dadaa eae aeaiiai XIV S curit lors de l utilisation ssh session xlv Symboles de s curit ss xlv D finitions ATTENTION AVERTISSEMENT et REMARQUE xlvi R capitulatif des messages d Alerte et d Avertissement se xlvii Mise la terre de I AutoProbe CP xlix Configuration de la tension d alimentation l Recommandation l usage du laser li Caracteristiques et performances pour l AutoProbe CP lvi D claration de Garantie de ThermoMicroscopes ernennen lix Garantie des Syst mes neufs et des Accessoires lix Garantie des pi ces remplac es u22u02200nsuesseennesnnesnnesnnenennnesnnennnennnnnnonnnen nn lix Information du fabricant ss non Rene ete ei Ix Comment utiliser ce guide de l utilisateur uucssusssesseesnesnnesnnesnnesnnennennnennnnsnen nenn lxi Part Il Learning to Use AutoProbe CP Advanced Techniques Chapter 1 NC AFM IC AFM and MFM Imaging 1 1 Introduction ste Bean ik ib ata pet ates 1 2 Vibrating Cantilever AFM Methods 1 3 Non Contact AFM NC AFM ie 1 3 Intermittent Contact AFM IC AFM sis 1 4 Magnetic Force Microscopy MFM
112. bel Xvi Preface laser power laser laser on off switch position intensity video display indicators indicators y S laser beam N steering screws Me WZ green O T prism TA 4 7J EN Jj PSPD 4 de u En up down O Of amp a 4 PSPD gt forward backward CAUTION LASER LIGHT DO NOT STARE INTO BEAM 0 2 mW AT 600 700 nm CLASS II LASER PRODUCT AVOID EXPOSURE LASER LIGHT IS EMITTED FROM THIS APERTURE n PER EN60825 1 1994 Figure 0 3 Location of laser controls indicators and labels on the probe head The controls and indicators shown above in Figure 0 3 have the following functions Laser power on off switch Turns the laser in the probe head on or off A red light in the switch is lit when the laser power is on Laser beam steering screws The two laser beam steering screws located on the top right side of the probe head are used to adjust the position of the laser beam hitting the cantilever The screws move the laser spot in two directions as shown in Figure 0 3 above If your system includes the optional CP optics you can monitor these adjustments using the optical view displayed on your video monitor PSPD adjustment screws There are two PSPD position sensitive photodetector screws on the probe head up down and forward backward These screws adjust the position of the PSPD in the probe head to center the reflected l
113. button which remains enabled for as long as it takes the system to generate the I V curve When the system is finished generating the I V curve the button is enabled and the I V curve is displayed in the I V Spectroscopy window The horizontal scale voltage is displayed on the x axis The starting value of the horizontal scale is shown on the left side of the curve and the units per grid division are shown on the right side of the curve Acquiring Current vs Voltage Data 5 9 The vertical scale current is displayed on the y axis The starting value of the vertical scale is shown at the bottom of the curve and the units per grid division are shown at the top of the curve 10 Select the dI dV option button to differentiate the current vs voltage curve The horizontal scale i e the x axis displays voltage The vertical scale 1 e the y axis should now display current voltage 11 Toggle between the current vs voltage curve and the dI dV curve by clicking the I V and dI dV option buttons respectively Generating an l V Curve at a Different X Y Location You can generate a current vs voltage curve at a different x y location in the image by changing the position of the green crosshair If the desired location is visible in the image you used to select the first location you can move to the new location by clicking and dragging the crosshair If the desired location lies outside of the region shown in the image you
114. c Force Microscopy works at the end of this chapter for details Thus an image taken using the Topography signal represents magnetic features on the sample surface Once you are familiar with the basic procedures for taking an MFM image you can move ahead to additional sections that describe using other signals to learn more about the magnetic properties of your sample You can also find out how to take follow up images of sample topography using either contact or non contact AFM methods and how to apply an electrostatic bias between the tip and the sample Summary of the Procedure The following steps summarize the procedures for taking an MFM image and can also be used as a quick reference Step 1 Set up the system 1 Connect cables and install a scanner as for NC AFM operation 2 Mount a sample on the non magnetic sample holder 3 Install the sample holder on the scanner 4 Install the appropriate probe head and an MFM probe cartridge If you have the standard AutoProbe CP system configuration Install the AFM NC AFM probe head If you have the multitask AutoProbe CP system configuration Install the multitask probe head and set the two mode switches on the probe head to the AFM and NC AFM positions Load an MFM chip carrier onto the NC AFM probe cartridge Load the cartridge in the probe head 1 36 Chapter 1 Step 3 Step 4 NC AFM IC AFM and MFM Imaging Turn on the AEM the computer and the
115. calibration file If you need to reinstall your software for some reason be aware that only the default scanner calibration parameter files will be installed in the c psi cal directory the working scanner calibration parameter files will not be installed You will have to copy the Calibrating a5 Micron Scanner 6 9 working scanner calibration parameter files from the backup copies you have in a different directory By reinstalling the backup copies you will not have to perform a complete scanner calibration again Now install the appropriate hardware and set up for taking a contact AFM image 1 Install a 5 um scanner as described in Chapter 2 Part I of this User s Guide CAUTION The power to the AEM must be turned OFF before you remove or install the scanner CAUTION The four screws that connect the scanner to the CP base unit must be securely fastened to ensure proper grounding When the four screws are securely fastened maximum instrument performance is ensured since vibrations are reduced 2 Place the 1 um gold grating sample on the sample holder If the grating is roughly square rotate the sample so that the edges of the grating are parallel with the x and y scan directions Later you will take an image and make adjustments to the position of the grating 3 Open ProScan Data Acquisition From Start point to the Program folder and select ThermoMicroscopes ProScan Then click the Data Acquisition ico
116. can s Data Acquisition software Spectroscopy mode is accessible as an item in the Mode menu or as the Spectroscopy icon 4 on the Toolbar When you enter Spectroscopy mode the Image Gallery on the right side of the Image mode and Move mode windows is replaced by the Spectroscopy window The Spectroscopy window includes a graph and software controls as shown in Figure 4 1 below Note The Image Gallery buffers remain accessible at the bottom right side of the window ProScan HI SPS INSTR CP OFF EC AFM HDM AFMLFM HD 100_0640 SCN UL20A BBC Ox Filg Mode Setup Tools Help vHeadON EE ELLE EE Move mode e 100 100 nN di i 1V Image mode High voltage Low voltage x Spectroscopy E a 0 nm 100 nm div V Save to buffer v Two way scan A AC 200 hm H OnN 1 H F Topography Als r Slope X Y Repeat ape s al Zoom Buffer_ i 0 ScanOFF Image Import qu uto 7 OMeasure 0 _f i Size u X offset u Y offset p Zm Run Acq Stop Reset Copy Load Save 2 0 0 i Extend Retract um LI Cal Sweep Calibrate Scan rate SetP nA Servo gain i 1 36 1 187 i 1 0 5 0 01 2 2584 00 0 000 nN Print Setup Z servo ms Smpl bias g
117. cantilever vibration amplitude matches that represented by the set point value displayed in Image mode Note If for any reason you want to re select the drive frequency after the system has performed an auto approach you need to lift the tip using the upper z direction pad This positions the tip away from the sample so that its free space resonant frequency can be determined 3 Switch to Image mode to view the Oscilloscope Display If the Topography signal is not already selected select it now from the Input Configuration dialogue box so that you can view the Topography signal trace on the Oscilloscope Display Also from within the Input Configuration dialogue box select both the right and left scan directions for the Topography signal Note The Topography signal is named for its representation of sample topography in NC AFM and IC AFM modes In all vibrating cantilever modes NC AFM IC AFM and MFM the Topography signal is the signal that comes from the feedback electronics and controls the z position of the scanner so that a constant force gradient between the tip and the sample is maintained Refer to the section How Non Contact AFM Works for a discussion of the relationship between the force gradient and sample topography In MFM mode magnetic samples and a magnetized tip are used Therefore the force gradient and thus the Topography signal may be dominated by magnetic rather than topographic features on the sampl
118. ce is ensured since vibrations are reduced 2 Place the 9 9 um grid sample on the sample holder Try to rotate the sample so that the grid lines are parallel with the x and y scan directions 3 Install the probe head Make sure that the LASER ON OFF switch on the probe head is in the OFF position before you install the probe head If you are using a multitask probe head set the AFM STM switch to the AFM position and the LFM NC AFM switch to the LFM position 4 Once the probe head is installed set the LASER ON OFF switch on the probe head to the ON position 5 Place an AFM chip carrier in the probe cartridge 6 Place the cartridge in the probe head Configuring the System Software Once you have installed the appropriate hardware you can configure the system software Values for all of the scanner calibration parameters are contained in a calibration parameter file Each scanner in your system has a working scanner calibration parameter file To direct the system to use a particular scanner calibration parameter file select that file when you configure the system software in the ProScan Database Configuration dialog box This can be done at any point during a working session by selecting Configure Parts from the Setup menu or by clicking the Configure Parts icon ee The names of available files are under the drop down list in the CP LS Scanner category of the ProScan Database Configuration dialog box Note
119. ce vs distance curves can be generated at different x y locations on a single image The Buffer scrollbox arrows allow you to scroll through the stored F vs d Acquiring F vs d Curves Along a Line Spectroscopy mode enables you to acquire sixteen equally spaced F vs d curves along a line that you select using the mouse This feature is useful for studying changes in characteristics of F vs d curves across an interface To acquire sixteen equally spaced F vs d curves along a line do the following 1 Take an image as you normally would for F vs d data acquisition The image should include the line where you want the F vs d curves to be taken Note Be sure that the Save to Buffer icon is ON before you take the image Otherwise the image will not be saved and therefore you will not be able to save the F vs d curves associated with the image 2 Click and drag the mouse on the image in the Active Display to define one endpoint of the line and the extent of the line Release the mouse to define the second endpoint The line you draw will appear on the image 3 Adjust parameters as described in the section Generating an F vs d Curve earlier in this chapter The parameter settings apply for all of the sixteen F vs d curves taken along the line 4 Click when you are ready to begin acquiring curves that can be saved with the image 5 Click the button when you are satisfied with the curves and wish
120. ched tip Shorter wires yield etched tips with lower aspect ratios 4 Setthe VOLTAGE knob on the electronics unit to 80 Set the SHUT OFF CURRENT knob to 0 5 Switch on the power by pressing the POWER button 5 To start the etching process press the START button The green light on the front panel will light and the etching process will begin Preparing and Loading STM Tips You will see tiny bubbles surround the immersed portion of the wire as it is etched The wire etches isotropically to produce a high aspect ratio tip After a few minutes you will see arcing in the solution As etching proceeds and the exposed surface area of the tip decreases the current drops When the current drops below the SHUT OFF CURRENT setting the green light on the front panel turns off The etching process is then complete When the etching process is complete and the green light is off the shortened tip will extend only about 0 5 to 1 mm below the surface of the solution You can experiment with different VOLTAGE and CURRENT SHUT OFF values to find optimum settings for the best tips Figure 2 3 below shows the shape of a good STM tip Figure 2 3 Good STM tip shape 6 To remove the etched tip lift out the tip electrode The tip electrode fits snugly so you may need to press down on the lid while you twist and pull the knob of the electrode Pull the tip out of the tip electrode using needle nosed pliers CAUTION Be careful n
121. ck on the system is prompted to load files pertaining to the installed hardware and mode of operation This procedure ensures that files are updated before an image is taken 5 Configure the system software for taking an AFM image by making the following selections Head Type Select the type of probe head AFMSTM AFMNCM or AFMLFM that you are using If you are using a multitask probe head select AFMLFM CP LS Scanner Select the file that has the scanner calibration values for the scanner you are using Head Mode AFM Beam Bounce Cantilever Select the file that corresponds to the type of cantilever you are using e g select ULO6B if you are using the B cantilever of a contact AFM Ultralever Calibrating a 100 Micron Scanner 6 31 Electrochemistry ON OFF OFF Voltage mode HI After you finish entering these selections click to return to the Move mode window 6 If you have not already done so reset the Z stage as described in Chapter 2 Part I of this User s Guide This synchronizes the position of the Z stage with the coordinate system of the software 7 Make sure that the power to the probe head is on If the power to the probe head is turned off turn it on by clicking the Head ON icon If the LASER ON OFF switch is in the OFF position turn it to the ON position Note If you are using a multitask probe head set the AFM STM switch to the AFM position and the LFM NC
122. cking the Offset scrollbox arrow Successively clicking the Offset scrollbox arrow decreases the starting value of the horizontal axis shifting the curve up on the graph 8 Shift the curve down by clicking the Offset scrollbox arrow Successively clicking the Offset scrollbox arrow increases the starting value of the horizontal axis shifting the curve down on the graph 4 20 Chapter 4 Force vs Distance Zooming in on a Region of Interest Often times you will want to zoom in on a particular portion of an F vs d curve you have generated You can do this graphically by defining a region of interest on the curve Or you can zoom in by changing the limits of the scanner s sweep range to cover a smaller portion of acurve Details of zooming in on an F vs d curve are described in two sections that follow Zooming in Graphically Using the Cursor To zoom in on a portion of an F vs d curve you can use the cursor to define a region of interest on the graph You define a region while the scanner is stopped The portion of the curve displayed on the graph changes immediately to reflect the area you define The resolution of the zoomed in area does not increase however until you resume sweeping of the scanner by clicking the or button At that point the same number of data points 1000 per curve are read over a smaller portion of the scanner s sweep range Therefore the resolution of the resulting F vs d curve increases 1 C
123. cope Display and acquire LFM data The Topography signal should be selected by default If it is not select Topography in the Available listbox then click the button This enables you to look at the Topography signal trace on the Oscilloscope Display and acquire AFM data In the Selected listbox click on LFM to select it Check both the right gt and the left lt checkboxes This enables you to obtain both left to right and right to left LFM data In the Selected listbox click on Topography to select it Check both the right gt and the left lt checkboxes This enables you to obtain both left to right and right to left AFM data Click the button to close the Input Configuration dialog box and return to Image mode Set up the system so that you can view all four images AFM and LFM right to left and left to right simultaneously Taking anLFM Image 3 17 Select Layout from the View menu to open the Image Layout dialog box Alternatively click the Layout icon E Click the Quad option button and then click the button This enables you to view all four images at once By positioning the cursor over a Layout image in Image mode and clicking the right mouse button you can see which image it is The image type is displayed at the bottom of the window Setting Scan Parameters 2 Select the input signal you wish to view from the drop down list below the Oscilloscope Display You should have a choice bet
124. croscope L ajustement haut bas est utile principalement pour la t te du microscope AFM LFM pour un syst me de configuration standard Indicateurs d intensit du laser Indique l intensit avec laquelle la lumi re refl t e du laser touche le PSPD photod tecteur sensible la position Pour une configuration standard il y a trois t tes de microscope AFM AFM NC AFM AFM LFM Il y a diff rents indicateurs pour les diff rentes t tes de microscope Recommandations a l usage du laser liii Note La t te de microscope AFM est comprise dans la configuration standard du systeme Les t tes de microscope AFM NC AFM et AFM LFM peuvent tre achet es s par ment Les indicateurs de la t te AFM sont montr s dans la Figure 0 3 ci dessus Pour cette t te de microscope l intensit amp de la lumi re du laser touchant le PSPD est maximis lorsque la colonne de quatre Leds rouge est allum e Les indicateurs des t tes de microscope AFM NC AFM et AFM LFM sont montr s dans la Figure 0 4 ci dessous Pour ces t tes de microscope lorsque la brillance du centre de la Led verte qui a une brillance variable est maximis e l intensit du laser touchant le PSPD est maximis laser intensity and position indicators for other probe heads AFM NC AFM AFM LFM probe heads probe heads RE Ch green analog analog for variable for variable brightness brightness Figure 0 4
125. ct microns textboxes 3 Type a value that is larger i e less negative in the Extend textbox You should see the right end of the red Piezo Adjustment bar move to the left 4 Type a value that is smaller in the Retract textbox You should see the left end of the red Piezo Adjustment bar move to the right 4 22 Chapter 4 Force vs Distance Making Point to Point Measurements on an F vs d Curve When the Measure option button is enabled you can measure horizontal and vertical distances between two points on an F vs dcurve The measurements are shown by coordinates X y dx dy below the curve The values of X and y are relative to the origin defined by the heavy horizontal and vertical lines on the graph The values of dx and dy are relative to the position of an anchor point which you set as described below Before you set an anchor point the values of dx and dy are relative to a default anchor point located at the upper left corner of the graph Try the following for practice 1 Select the Measure option button This sets the function of the cursor so that its coordinates on the graph are displayed below the graph 2 Use the mouse to place the cursor on the F vs d graph The cursor should change to a black crosshair 3 Use the mouse to move the crosshair to a position on the graph where you would like an anchor point To define this point as the anchor point click the mouse The crosshair will remain at th
126. ction as described for taking an NC AFM image 2 Adjust the gain set point and slope parameters if necessary The purpose of adjusting the scan parameters is to obtain stable imaging conditions which depends on obtaining a stable signal trace that is free of glitches tip snap ins and saturated or truncated signals Iterative adjustment of some of the parameters listed below is generally required in order to produce a high quality image size gain rate slope setpoint The design of the instrument supports adjusting all of the parameters listed above in real time during a scan without having to lift the tip Adjust the parameters using the same guiding principles as described in Taking an NC AFM Image Starting a Scan After you have set and or adjusted the scan parameters listed in the previous section so that the Topography signal trace in the Oscilloscope Display is stable and repeatable start taking an image 1 Click the button below the Oscilloscope Display to start a scan You may need to adjust the drive amplitude the drive value or the imaging amplitude the set point value while a scan is being taken Larger drive imaging amplitudes may work best for imaging steep features on rough samples However if the drive amplitude is too large it may exceed the lock in amplifier s input range The lock in amplifier detects the AC signals from the signal generator and the cantilever If the signal trace bec
127. ction pad and let go of the pad when the tip is within a few millimeters of the surface 10 With the optics still focused on the sample surface use the z direction pad to slowly lower the tip further stopping as it starts to come into focus This should position the tip close to but not in contact with the sample surface You are now ready to perform an auto approach 2 20 Chapter 2 STM Imaging Performing an Auto Approach Clicking the button in STM mode starts the following sequence of steps a The scanner extends moving the sample toward the tip with feedback enabled b The system monitors the tunneling current checking for the set point value as the scanner extends c If the set point value is obtained then the auto approach process stops d Ifthe set point value is not obtained with the scanner fully extended then the system retracts the scanner and lowers the probe head one step of the stepper motor toward the sample Steps a through d are repeated until the tunneling current matches the set point value 1 Click the button in Move mode to initiate an auto approach The auto approach sequence is a slow process You may see the reflection of the tip flicker up and down in the optical view with each step Watch the Current signal displayed on the open DVM window The Current signal should approach the set point value and then stop CAUTION The tip should never touch the surface in STM mode If the tip
128. ctions that follow Setting Up to Acquire an F vs d Curve This section describes the procedures for setting up to take an F vs dcurve Included is a subsection that describes how to calibrate the vertical axis of the curve with units of force The calibration procedure must be performed any time you switch cantilevers Taking a Contact AFM Image Start by setting up the system for contact AFM mode data acquisition Details are described in Chapter 2 Part I of this User s Guide 1 Install a 100 um scanner if you have one The 100 um scanner is preferable because it has the largest z range or throw The z range of the scanner must be large enough to include the snap back point of the cantilever which is the point where the cantilever tip snaps off the sample surface Note If you want to acquire F vs d curves using a 5 um scanner use a stiff cantilever such as an NC AFM Ultralever A stiffer cantilever snaps back sooner so the snap back point is more likely to be within the scanner s z range of motion CAUTION The power to the AEM must be turned OFF before you remove or install the scanner 4 10 Chapter 4 Force vs Distance CAUTION The four screws that connect the scanner to the CP base unit must be securely fastened to ensure proper grounding When the four screws are securely fastened maximum instrument performance is ensured since vibrations are reduced 2 Install a probe head
129. ctronics unit Connect the two leads on the opposite end of the cable to the carbon electrode and the tip electrode The lead with the smaller red lug connector attaches to the tip electrode and the other lead attaches to the carbon electrode Fasten the leads using the two screws in the lid WARNING Whenever you work with KOH wear rubber gloves and protective goggles 4 Lift up the lid and add 50 ml of KOH pellets to the beaker Then add deionized water to make 375 ml of solution Stir the solution with a glass stirring rod The tip etcher is now set up and ready for use Operating the Tip Etcher 1 Cut off a piece of wire between 1 and 1 5 inches long using a strong pair of wire cutters Ordinary wire cutters will be damaged 2 Lift out the tip electrode holding it by the gnurled knob The tip electrode fits into the lid snugly so you may need to press down on the lid while you twist and pull the knob Use needle nose pliers to insert one end of the wire into the hole in the end of the tip electrode Push the wire all the way into the hole so that it fits snugly Make sure the tip doesnt drop out when you hold the electrode with the tip pointing down 3 Reinsert the tip electrode into the hole in the lid Push the tip electrode in all the way so that it fits snugly There should be at least 1 cm of wire showing above the solution The length of the immersed portion of the wire affects the aspect ratio of the et
130. d graph Use the F vs d data displayed on the Spectroscopy window graph to adjust F vs d parameters You can adjust parameters while the scanner is sweeping or while it is stopped 13 Use the Piezo Adjustment bar to graphically adjust the scanner s sweep range Use the mouse to grab the ends of the Piezo Adjustment bar and move the ends by dragging the mouse Alternatively you can use the mouse to click and drag on the center of the red bar moving both limits simultaneously Or you can type in new values in the Extend and Retract micron textboxes Adjust the length of the red bar so that the portion of the F vs d curve that you are interested in is covered 4 18 Chapter 4 Force vs Distance Note At some point during scanner extension the signal that represents cantilever bending may saturate This means that further deflection of the cantilever cannot be measured by the PSPD If you see the signal saturate along the vertical axis try adjusting the alignment of the PSPD Adjusting the alignment of the PSPD optimizes the range of cantilever deflection that the PSPD can detect 14 Click the button to open the Spectroscopy Setup dialog box 15 Adjust the sweep rate and the number of curves to be averaged if desired 16 Click the button to register any changes made and exit the dialog box 17 When the parameter values are set such that you are satisfied with the F vs d curve displayed on the graph click the but
131. d not affect the periodicity of the image If the spacing of the corrugations changes then what you see in the image is due to noise Taking an STM Image of a Graphite Sample This section provides the basic instructions for taking an image of a graphite sample 1 With the probe head turned off select Configure Parts from Setup menu to open the ProScan Database Configuration dialog box Within this dialog box make the following selections Head type AFMSTM Scanner Select the name of the file with the scanner calibration parameters appropriate for the scanner you are using Head mode STM Tunneling Tip AIR Electrochemistry ON OFF OFF Voltage mode LO Click to close the dialog box 2 Follow the instructions of previous sections to take an image in constant height mode using the following values for key scan parameters set point 1 to 5 nA sample bias 0 V tip bias 100 to 500 mV scan rate 20 to 40 Hz scan size 50 to 100 Summary 2 27 Summary This chapter provided you with instructions for taking an STM image Some of the topics covered include the following preparing and loading STM tips setting up the system hardware and software taking an STM image of a gold calibration grating constant current vs constant height mode STM images optimizing scan parameters taking an STM image of a graphite sample After reading this chapter you should be abl
132. den ber den Gebrauch des Benutzerhandbuches xli Schadstoffe wurden von den L ndern der Europ ischen Gemeinschaft als Stoffe und Zubereitungen gem ss EG Richtlinie vom 18 9 1979 Artikel 2 definiert Mit Systemkomponenten welche mit Schadstoffen in Kontakt kamen muss folgendes beachtet werden Kontaminierte Komponenten sind vor der R cksendung zu ThermoMicroscopes entsprechend den Strahlenschutzvorschriften zu dekontaminieren Zur Reparatur oder Wartung eingehende Ger te m ssen mit deutlich sichtbarem Vermerk Frei von Schadstoffen versehen sein Derselbe Vermerk ist auch auf dem Lieferschein und Anschreiben anzubringen xlii Vorwort und bersicht ber die Benutzung dieser Bedienungsanleitung Die Bedienungsanleitung zum AutoProbe MS ist in drei einfach zu ben tzende Abschnitte unterteilt Die Abschnitte beinhalten das folgende Abschnitt I Lernen das AutoProbe CP zu gebrauchen Grundaufnahmetechniken Abschnitt II Lernen das AutoProbe CP zu gebrauchen Fortgeschrittene Aufnahmetechniken Abschnitt II Software Verweis Die Inhalte der oben aufgeliesteten Abschnitte sind im Detail in den folgenden Sektionen beschrieben Abschnitt I Lernen das AutoProbe CP zu gebrauchen Grund Aufnahmetechniken Abschnitt I dieser Bedienungsanleitung Lernen das AutoProbe CP zu gebrauchen Grund Aufnahmetechniken beinhaltet ein Einf hrungskapitel und drei praktische Schulungen Kapitel 2 bis 4 Beim Durcharb
133. desired x y location and click the mouse Set the range of the bias voltage that will be applied to the sample during current vs voltage data acquisition The From and To textboxes list the lower and upper limits respectively of the bias voltage range The maximum bias voltage range is from 10 to 10 volts This range is selected by default The values you choose depend on the sample you are using For example if your sample is graphite you may choose a range that is roughly 1 to 1 volts Set the rate at which the system will sweep the selected bias voltage range To enter a rate type the value in the Rate scrollbox and then press the Enter key Or use the scrollbox arrows to scroll through the range of values The ramp rate is displayed in units of Hz and can have a value between 0 01 and 10 Hz For now leave the rate at its default value which is 1 Hz Set the number of sweeps that will be used to generate an averaged current vs voltage curve In the Average scrollbox enter the number of sweeps and then press the Enter key Or use the scrollbox arrows to scroll through the range of values For now type in a value of 5 curves to be averaged As you generate I V data you can monitor whether to increase or decrease the number of curves that are averaged Click the button to disable the feedback loop and begin generating a current vs voltage curve When you click the button it changes to a
134. detail below First you will check or enter the value of the cantilever force constant The cantilever force constant is a database parameter ErrSigNewtonPerMeter accessible in the Manual Calibration Entry dialog box If you selected the appropriate cantilever from the Beam Bounce Cantilever listbox of the ProScan Database Configuration dialog box then the correct force constant value may already be loaded in the software database It is always a good idea however to check the value as described in the steps that follow Note Values for the cantilever force constant of the cantilever you are using are listed in a section at the end of this chapter For the most current values check a current version of the appropriate cantilever data sheet If you do not wish to check the value now you will have an opportunity later to enter a value manually from within the Spectroscopy window 4 12 Chapter 4 Force vs Distance 1 Select Calibration Edit from the Setup menu to open the Manual Calibration Entry dialog box Click when the Warning box asks you if you want to proceed 2 Choose Probe from the Category listbox and select ErrSigNewtonPerMeter from the Calibration Values listbox If the value shown for this parameter is not the correct value for the cantilever you are using or if the value listed is Invalid then you need to enter the correct value 3 To enter a new probe calibration value select the value that appears
135. determined will not be used Click to register the changes and close the dialog box As a check repeat the steps of the earlier section Taking an Image and Determining Calibration Parameters making sure that distances reported by the software now match their correct values After the corrections are made you should see an improvement in the accuracy of scan sizes for small scans when you are operating in high voltage mode First Order Calibration in Low Voltage Mode The system software uses separate sets of scanner calibration parameter values for high and low voltage modes Therefore if you will be operating frequently in low voltage mode you need to repeat the first order scanner calibration procedures while operating in low voltage mode Select Low Voltage from the Mode menu 6 16 Chapter 6 Scanner Calibration 22 Follow Steps 1 through 17 of the earlier section Taking an Image and Determining Calibration Parameter Values In low voltage mode however the maximum scan size is roughly 1 to 1 5 um depending on the scanner Therefore you need to select a calibration sample other than the um gold calibration grating In addition as you calculate corrected values of first order calibration parameters for low voltage mode be sure to enter the values in the Low Voltage column of your table of calibration parameters 3 Follow Steps 1 through 10 of the previous section Editing the Scanner Calibratio
136. directly to the sample holder To install an MFM sample holder 1 Unscrew the standard sample holder and set it aside 2 Screw the MFM sample holder into the scanner making sure that there is contact between the spring loaded electrical contact in the scanner and the sample holder 1 38 Chapter 1 NC AFM IC AFM and MFM Imaging Installing the Probe Head and Probe Cartridge 1 Install the appropriate probe head by sliding it onto the support arms of the XY Translation Stage as described in Part I of this User s Guide Make sure that the LASER ON OFF switch is in the OFF position before you install the probe head If you have the standard AutoProbe CP system configuration Install the NC AFM probe head which is labeled AFM NC AFM to distinguish it from other probe heads you may have A connector on the rear of the probe head plugs into a connector on the back of the translation stage If you have the multitask AutoProbe CP system configuration Install the multitask probe head and set the two mode switches on the probe head to the AFM and NC AFM positions Once the probe head is installed turn the LASER ON OFF switch to the ON position 2 Select a cantilever For MFM imaging we recommend that you use MFM Microlevers The resonant frequency for MFM Microlevers is typically around 85 kHz Before loading the MFM cantilever pass the cantilever tip between the poles of the tip magnetizer provided with your MFM toolkit
137. e software Aligning the Deflection Sensor This section describes the procedures for aligning the deflection sensor for an AFM NC AFM probe head of a standard AutoProbe CP instrument If you are using a multitask probe head then the procedures for aligning the deflection sensor are described in the section Aligning the Deflection Sensor in Chapter 2 Part I of this User s Guide To align the deflection sensor for an AFM NC AFM probe head you must first steer the laser beam so that it reflects off of the back of the cantilever Then you move the position sensitive photodetector PSPD so that it is aligned with the laser spot The procedure for aligning the PSPD for the AFM NC AFM probe head is similar to that for the AFM probe head refer to Part I of this User s Guide for details However the laser position and intensity indicator for the PSPD of the AFM NC AFM probe head is different as shown in Figure 1 1 1 12 Chapter 1 NC AFM IC AFM and MFM Imaging Laser position and intensity Optical view indicator Laser beam YX steering screws u N N as Ko PSPD Up down PSPD forward backward Figure 1 1 Location of the controls for aligning the deflection sensor on an AFM NC AFM probe head The position of the laser spot on the PSPD is indicated in the same way as for the AFM probe head with a red light above and below the green light For the AFM NC AFM probe head however
138. e es Three phase alternating current l Ground earth terminal D Protective conductor terminal 177 Frame or chassis terminal Y Equipotentiality l Power on X Preface Table 0 1 continued Safety symbols and their function Symbol Function Power off Equipment protected by double or reinforced insulation AX Refer to system documentation A Electric shock risk Definitions Warning Caution and Note There are three terms that are used in this User s Guide to alert you to matters related to the operating safety of AutoProbe CP warning caution and note These terms are defined in Table 0 2 below Table 0 2 Safety terms and their definitions Term Definition Warning Alerts you to possible serious injury unless procedures described in this User s Guide are followed exactly Do not proceed beyond a warning until conditions are fully understood and met Caution Calls your attention to possible damage to the system or to the impairment of safety unless procedures described in this User s Guide are followed exactly Note Calls your attention to a rule that is to be followed or to an out of the ordinary condition It is important that you read all warnings cautions and notes in this manual carefully Warnings cautions and notes include information that when followed ensures the operating safety of your AutoProbe CP system Xi Summary of Warnings and Cautions
139. e Fm and van der Waals force Fy 1 62 Chapter 1 NC AFM IC AFM and MFM Imaging There are two symmetric magnetic force vs distance curves one represents forces acting when the magnetic interaction is attractive negative F values and the other represents forces acting when the magnetic interaction is repulsive positive F values Both types of forces could be present for a single sample since they could represent different magnetic domains on the sample surface The net force between the atoms on the cantilever tip and atoms on the sample surface is the sum of the magnetic force repulsive or attractive and the van der Waals force F Fn Fy 3 Similarly the net force gradient experienced by a vibrating cantilever is the sum of the gradient of the magnetic force and the gradient of the van der Waals force dF dz dF dz dF dz 4 where z is the tip to sample spacing The key to understanding MFM methods is to identify the force or force gradient term that is dominant in a given tip to sample spacing regime For MFM the tip to sample spacing typically lies in the range of ten to hundreds of angstroms or in the non contact regime This range of spacing for MFM operation can be further divided into far field and near field regimes as indicated on Figure 1 9 The far field and near field regimes are defined based on whether the force gradient is dominated by the magnetic or the van der Waals force gradient
140. e PSPD forward backward screw slightly until the intensity of the green light is maximized If you do not see any of the LED s light up try adjusting the PSPD up down screw You may have to repeat Steps 4 and 5 until you see the green light and its brightness has been maximized 1 14 Chapter 1 NC AFM IC AFM and MFM Imaging Setting NCM Parameters When you take a contact AFM image you specify values for scan parameters such as the scan rate the scan size and the gain For a non contact AFM image you specify the following scan parameters in addition to the scan parameters that you set for contact AFM imaging Drive amplitude drive parameter Drive frequency Imaging amplitude set point parameter This section defines these scan parameters that are specific to NC AFM imaging and describes how to select their values Sections that follow guide you in setting other scan parameters and then in taking an NC AFM image The NC AFM scan parameters are set in the NCM Frequency Set dialog box which is displayed when you select NCM Frequency from the Setup menu A drawing of this dialog box is shown in Figure 1 2 NCM Frequency Set x 100mum div Set 0 184 Drive 2 cross hair 0 kHz f 96000 Hz 100KHz div Zoom In Zoom Out Refresh Done Help Figure 1 2 The NCM Frequency Set dialog box Selecting a Dri
141. e Setup menu of the Image mode window select NCM Frequency to view the NCM Frequency Set dialog box Select a drive frequency drive amplitude drive and imaging amplitude set point for the scan The drive frequency you choose should be on the left side of the cantilever s main resonance peak Perform an auto approach In Move mode use the z direction pad to lower the tip so that it is close to the sample Click the button to initiate an auto approach The auto approach stops when the cantilever s vibration amplitude matches the value represented by the set point parameter displayed on the Image mode window Enter Image mode to view a Topography signal trace Optimize the set point parameter by iteratively reducing the set point while monitoring the Topography signal trace and the Z Piezo bar Re approach the sample if necessary 1 28 Chapter 1 NC AFM IC AFM and MFM Imaging Step 4 Set scan parameters 1 Set the scan rate scan size number of data points per image and fast scan direction 2 Adjust the drive set point gain and slope parameters if necessary Step 5 Start a scan 1 Click the button to begin acquiring an image 2 While imaging continue to monitor the scan parameters and adjust them as needed The sections that follow explain these steps in detail and include important hints and tips for optimal intermittent contact mode operation Setting Up the System The procedures for se
142. e as reported by the software for scan sizes up to the full range of the scanner when you are operating in high voltage mode If you would like you can continue and perform the procedures for calibrating the scanner sensitivity in Z 6 20 Chapter 6 Scanner Calibration Calibration of Scanner Sensitivity in Z Calibrating the scanner sensitivity in the z direction means calibrating the voltages sent to the scanner with motion of the scanner in the z direction The procedure is similar to that for calibrating the scanner sensitivity in the x and y directions except that you need to use a sample with a z step height of a known distance a step height standard The z range of scanner motion for a 5 um scanner in high voltage mode is roughly 2 5 um and in low voltage mode it is roughly 0 8 um Choose a step height standard that is appropriate for these ranges Software correction for scanner movement in the z direction includes only one first order parameter the MicronPerDac_SZ parameter Second order correction is not necessary since scanner motion in the z direction is usually small The value of the MicronPerDac_SZ parameter varies depending upon whether you are operating high or low voltage mode Therefore you need to perform the first order calibration procedure in both high and low voltage modes if you expect to be operating in both modes frequently Taking an Image and Determining a Calibration Parameter Value 1 Install
143. e location of the ground connection is shown in Figure 0 1 below AEM Ground connection H E00 Figure 0 1 Rear panel of the AEM showing the location of the ground connection Setting the Line Voltage The line voltage selection must correspond to the line voltage of the country where the AutoProbe CP system is operated The line voltage selection is made using a line voltage selector The line voltage selector unit is located on the rear panel of the AEM The line voltage can be set to the following voltages 100 V 120 V 220 V or 240 V To change the line voltage selection follow these steps xiv Preface 1 Make sure the power to the AEM is turned off 2 Unplug the AEM s power cord from the power outlet 3 Remove the cover of the line voltage selector unit using an appropriately sized screwdriver 4 Insert an appropriately sized tool into the line voltage selector slot and use the tool to remove the line voltage selector wheel from the unit 5 Set the line voltage on the line voltage selector wheel to the desired value 100 V 110 V 220 V or 240 V 6 Put the line voltage selector wheel back into its location in the unit Make sure that the desired voltage is shown in the window 7 Install the cover onto the line voltage selector unit The line voltage should now be set to the appropriate value XV La
144. e obtaining a signal trace that seems representative of the sample topography try moving to a slightly different location on the sample surface and then 1 22 Chapter 1 NC AFM IC AFM and MFM Imaging repeating the approach procedure If the approach is still unsuccessful try the following troubleshooting tips If there is an error message displayed in Message log at the bottom of the screen read the message There may be more than one problem that could generate a single error message Systematically check possible causes of the error message to identify the problem The auto approach may not be working because the PSPD is not properly aligned An error message will state that either the A B signal is too high or the intensity of laser light on the PSPD represented by the A B signal is too low In this case you can adjust the position of the PSPD while watching the indicator lights as described in the earlier section Aligning the Deflection Sensor Once the PSPD is properly aligned the auto approach should work After trying the troubleshooting tips listed above try again to perform an auto approach After a successful approach the signal trace should reflect the sample topography If the approach is still unsuccessful try using a different cantilever Setting Scan Parameters This section describes factors to consider when setting and adjusting the scan size scan rate gain and slope parameters Adjustment of
145. e position where you clicked and the cursor will change to a second black crosshair As you move the mouse the coordinates of the second crosshair X y as well as its position relative to the anchor point dx dy are reported below the graph Generating an F vs d Curve at a Different X Y Location You may want to generate an F vs d curve at an x y location on your sample that is different from the first location you selected If the desired location is visible on the image you used to select the first location you can move to the new location by changing the position of the crosshair on the image shown in the Active Display If the desired location lies outside of the region shown in the image you must take a new image To generate an F vs d curve at a new location do the following 1 Using the mouse move the cursor to the x y location on the image where you want to acquire F vs d data and click The cross will appear at the new x y location on the image 2 If desired change the sweep range of the scanner the sweep rate and the number of sweeps as described in the section Generating an F vs d Curve earlier in this chapter Acquiring Force vs Distance Data 4 23 3 Click the button if you would like to adjust parameters as F vs d curves are generated 4 Once you are satisfied with your parameter selections click the button 5 Click the button to acquire an averaged F vs d curve Up to sixteen for
146. e set point parameter in the Set Point scrollbox in Image mode The set point is the reference current value that the system checks for during the approach If you leave the set point unchanged for the scan then it is the tunneling current value that will be maintained during the scan A third parameter you need to set is the gain of the feedback loop Other parameters such as the number of pixels per scan line are set to default values that you do not need to change The default number of pixels per scan line is 256 Also the Z Servo checkbox should be enabled by default Note If you have a MAP module connected to your system be sure that the module is turned off the gray button should be out before you begin taking an STM image The procedures provided here are for taking a constant current image which represents a surface of constant tunneling current as the distance the scanner needs to move in order to maintain the set point current value Detailed descriptions of both constant current and constant height mode STM images are given in a later section of this chapter Note If you have the multitask AutoProbe CP system configuration In order to facilitate the approach process you may need to change the value of a calibration parameter With the power to the probe head turned off select Calibration Edit from the Setup menu to open the Manual Calibration Entry dialog box Click the button of the warning box to proceed then choo
147. e surface Taking an MFM Image 1 41 The absolute value of the default set point parameter typically sets the tip far enough away from the sample surface that neither magnetic nor topographic features appear on the Topography signal trace At this distance the Topography signal represents long range air damping effects on the cantilever which are not consistent between the left to right and right to left signal traces Monitor the left to right and right to left Topography signal traces Lack of correlation is an indication that the tip is too far away from the sample to detect magnetic features Begin now to incrementally decrease the absolute value of the set point parameter by clicking on the up arrow of the Set Point scrollbox Continue to monitor the Topography signal traces in both directions When the left to right and right to left signal traces overlap the tip has entered the distance regime in which the Topography signal represents features on the sample surface For samples that are not magnetically weak the magnetic force gradient is dominant over the van der Waals force gradient far from the sample Thus the first features to appear represent magnetic properties of the sample not topographic features See the section How Magnetic Force Microscopy Works for details As you decrease the set point value monitor the Z Piezo bar the green bar located below the Toolbar which graphically represents the z position of the
148. e to take an STM image of a relatively straightforward sample such as the gold calibration grating provided with your system or a graphite sample Once you become familiar with the effects of tip quality and of varying scan parameters such as current and bias settings you will be ready to move forward and image more complicated surfaces 2 28 Chapter 2 STM Imaging Chapter 3 LFM Imaging 3 2 Chapter 3 LFM Imaging Introduction This chapter describes how to operate your AutoProbe CP instrument in lateral force microscopy LFM mode In this chapter you will find information on the following topics how LEM works the usefulness of having information from both AFM and LFM images available how to take images that reflect topographic and frictional information simultaneously The first section of the chapter which describes how LFM works provides background material that prepares you for the procedural section at the end of the chapter The procedural section is comprised of step by step instructions that guide you through the process of obtaining simultaneous AFM and LFM images How Lateral Force Microscopy LFM Works 3 3 How Lateral Force Microscopy LFM Works Lateral force microscopy LFM is similar to atomic force microscopy AFM except that an instrument operating in LFM mode is equipped with a cantilever detection scheme that measures both vertical and lateral bending of the cantilever This differs from A
149. ections you can use a um gold calibration grating provided with standard AutoProbe CP systems or a9 9 um grid provided with multitask AutoProbe CP systems For the calibrations in the z direction you will need a z height calibration standard This section includes instruction for the following procedures setting up the system for scanner calibration calibrating the xy detector calibrating the z detector running the scanner calibration routine to calibrate the detector offsets and scanner sensitivity in x y and z Setting up the system for calibrating the scanner consists of installing the appropriate system hardware configuring the system software and performing an auto approach These procedures are described in detail in the following sections Installing the System Hardware This section assumes that your instrument has been installed by a ThermoMicroscopes representative and that all of the cables are properly connected It also assumes that you are using the 9 9 um grid provided with multitask AutoProbe CP systems as a calibration sample 1 Install a 100 um scanner CAUTION The power to the AEM must be turned OFF before you remove or install the scanner 6 28 Chapter 6 Scanner Calibration CAUTION The four screws that connect the scanner to the CP base unit must be securely fastened to ensure proper grounding When the four screws are securely fastened maximum instrument performan
150. ed to reinstall the software the default values of all calibration parameters will be restored 9 Calculate a new value for the DetMicronPerAdc_SX calibration parameter using the following formula correct distance correct cal value existing cal value x 8 measured distance 1 For example if you ask the software to measure the distance between 10 grid lines along the x axis and it produces a value of 80 um and the existing DetMicronPerAdc_SX value is 140 then you should change the value as follows DetMicronPerAdc_SX 140 xt 155 9 10 Enter the correct value for the DetMicronPerAdc_SX parameter in your table 11 Repeat Steps 7 through 9 for the y axis This time if you ask the software to measure the distance between 10 grid lines along the y axis and it produces an incorrect measurement then you need to use Equation to calculate a new value for the DetMicronPerAdc_SY parameter 12 Enter the correct value for the DetMicronPerAdc_SY parameter in your table You should now have values recorded in your table for both of the xy detector calibration parameters DetMicronPerAdc_SX and DetMicronPerAdc_SY Next you will enter these values into the scanner calibration parameter file 6 34 Chapter 6 Scanner Calibration Editing the Scanner Calibration File 1 From the Move mode window use the z direction pad to withdraw the tip from the sample 2 Turn off the probe head by either de
151. eding the tip through the hole until only about 3 mm of the sharp end shows Try to keep the wire reasonably straight as you feed it through the hole Note Quite often the back end of a tungsten tip splinters and becomes difficult to fit through the hole If this happens try trimming off the end with wire cutters to remove the splinter You will find it easier to see the tip in the on axis optical view if the vertical distance between the tip and the underside of the cartridge is between 2 and 3mm However since you will mainly be using the side view this tip length is not required To check that the tip length is about right compare the STM cartridge with an AFM cartridge that has a cantilever chip loaded The STM tip should extend out about as far as the AFM cantilever chip does on the AFM cartridge 3 Tighten the set screw on the top side of the STM cartridge using an allen wrench The set screw is a 1 16 allen head Taking an STM Image 2 11 After inserting the wire and tightening the set screw cut the back end of the tip using a pair of wire cutters The back end of the tip should not extend more than about 5 mm Otherwise the back end of the wire may scratch the objective lenses of the optical view CAUTION Be careful to cut the back end of the wire short enough to avoid scratching the objective lens To store an STM cartridge with a tip loaded To store an STM cartridge place the cartridge in a container w
152. eiten der Schulungskapitel lernen sie die Grundkentnisse welche ben tigt werden um AFM Bilder aufzunehmen Beginnen sie mit lesen des Kapitel 1 AutoProbe CP Basics zur Einf hrung in die Systemkonfigurationen und Komponenten des AutoProbe CP Arbeiten sie sich dann durch die Schulung in Kapitel 2 Setting Up to Take an Image lehrt sie die Systemharware und Software f r AFM Mode zu konfigurieren Genauer gesagt werden sie die folgenden Prozeduren lernen das Verbinden der Kabel entfernen und einrichten des Messkopfes und des Scanners sowie das laden einer Probe und eines Messf hlers Kapitel 3 Taking an AFM Image lehrt sie die Software f r AFM Mode zu konfigurieren ein Auto Approach einzurichten und auszuf hren und ein AFM Bild aufzunehmen Kapitel 4 Taking Better Images erkl rt wie ein Scan und die R ckkoppelungsparameter f r bessere Aufnahmen optimiert werden k nnen sowie das sichern und laden von Bildern Abschnitt Il Lernen das AutoProbe CP zu gebrauchen Fortgeschrittene Aufnahmetechniken Abschnitt II dieser Bedienungsanleitung Lernen das AutoProbe CP zu gebrauchen Fortgeschrittene Aufnahmetechniken beinhaltet praktische Schulungen ber die Bedinung des Ger tes mit den folgenden Methoden STM LFM NC AFM IC AFM und MFM Er f hrt sie aussedem in die fortgeschrittenen F higkeiten des AutoProbe CP s ein wie Kraft Abstand Kurven Strom Spannungs Kurven und das kalibrieren des Scanners ber den
153. elected drive frequency corresponding to this point is displayed at the center of the line below the plot You may want to make adjustments to the value of the drive frequency to optimize its position on the resonance peak Follow these steps to select a drive frequency Taking an NC AFM Image 1 17 After the first sweep is finished click the button This prompts the system to re sweep over a smaller frequency range around the frequency marked by the cross hair Zoom in until the horizontal scale is divided into 5 KHz divisions where the peak width is about one fourth of the full range on the plot You should be able to check to see if the cross hair at the peak is positioned near the true peak or at a nearby smaller peak Zooming in on a peak shows much more structure including multiple peaks and often split peaks Since the plot has higher resolution the optimum drive frequency the point with the steepest slope is reselected Vary the value of the drive parameter until the maximum peak height of the response curve is roughly one third of the full vertical scale Examine the shape of the main resonance peak The ideal peak to use should have the following properties The peak should be reasonably symmetric The peak should be narrow The peak should not have glitches or shoulders at the location of the cross hair A broad peak may be due to a blunt cantilever tip and may result in a vibration amplitude that is too s
154. ency means that the cantilever s vibration amplitude decreases with decreasing tip to sample spacing Refer to the section How Non Contact AFM Works at the end of this chapter for details Since the absolute value of the set point parameter is related to the imaging amplitude smaller absolute values of the set point parameter correspond to smaller tip to sample spacings Taking an NC AFM Image 1 19 The value of the set point parameter can be viewed graphically in the NCM dialog box as a horizontal red line that cuts across the response curve peak at about half of the maximum peak height This is the default value of the set point parameter You can adjust the value of the set point by using the mouse to drag the horizontal red line up or down on the plot The set point parameter can be represented in units of micrometers or in arbitrary units eArbs When represented in arbitrary units the value is a negative number between 0 and 2 The set point value is displayed in the top line of the NCM dialog box as for example Set 0 075 Note You can change the units of the set point by selecting Servo Unit from the Setup menu and then selecting a new unit from the Servo Set Point drop down list As mentioned in the earlier section Selecting a Drive Frequency changing the servo units also changes the vertical axis units for the frequency response curve in the NCM dialogue box 1 For now leave the set point parameter at its de
155. er tip Note Don t try to maximize the brightness of the laser spot you see in the optical view Your goal is to produce the maximum amount of reflected light hitting the PSPD When the spot is positioned so that most of the laser beam is reflected onto the PSPD the laser spot on the back of the cantilever is not necessarily bright After this step you may see one red LED or the green LED lit on the laser position and intensity indicator Whether or not you see a light continue on with the next step When the laser spot is reflecting off of the back of the cantilever tip adjust the position of the PSPD to maximize the laser intensity incident on the PSPD Note Generally if the deflection sensor has been previously aligned you only need to use the PSPD forward backward screw You rarely need to use the PSPD up down screw Using the appropriately sized Allen wrench adjust the PSPD forward backward screw until the laser intensity hitting the PSPD is maximized Maximum intensity is indicated when the green LED is brightly lit The green LED is analog and its brightness varies with the intensity of the laser spot hitting the PSPD The two red LED s are digital If either red LED is lit then the laser is not positioned correctly Usually a quarter turn of the PSPD forward backward screw switches between the two red lights Somewhere between these two positions the green LED lights up When you see the green light adjust th
156. es for the three parameters listed above are contained in a calibration parameter file Every scanner has its own file You direct the system to use a particular scanner calibration parameter file by selecting its filename when you configure the system software Specifically at any point during a working session you can select Configure Parts from the Setup menu to view or change the scanner calibration parameter file that the system is set to use The names of available files are included in the drop down list labeled CP LS Scanner Typically the filenames refer to the scanner s size For example the file containing the calibration parameter values for a 100 um scanner might be called 100UM Calibrating a 100 Micron Scanner 6 27 The values of scanner calibration parameters are accessible in a dialog box called Manual Calibration Entry which opens when you select Calibration Edit from the Setup menu The three calibration parameters listed above are grouped in the Scanner Det category of the Manual Calibration Entry dialog box In the tutorial section that follows you will learn how to manually calibrate the detectors You will also learn how to prompt the system to calibrate the detector offsets and the scanner sensitivity automatically Scanner Calibration Procedures This section of the chapter provides step by step instructions for calibrating a 100 um scanner for an AutoProbe CP instrument For the calibrations in the x and y dir
157. et point parameter and thus the tip to sample spacing that corresponds to the default set point value is typically too large for the system to detect the sample topography Begin now to incrementally decrease the absolute value of the set point parameter by clicking on the up arrow of the Set Point scrollbox As mentioned in the previous section decreasing the set point absolute value causes the scanner to extend As you decrease the value monitor the Z Piezo bar the green bar located below the Toolbar which graphically represents the z position of the scanner within its total range of motion The Z Piezo bar should show the scanner extending as you decrease the set point absolute value Taking an IC AFM Image 1 33 5 Decrease the set point parameter and re approach the sample if necessary until the tip and the sample are in intermittent contact the sample topography is represented by the Topography signal trace and the Z Piezo bar shows that the scanner is operating in the middle of its z range 6 If you have trouble obtaining a signal trace that is representative of the sample topography try moving to a different location on the sample surface and then repeat the approach procedure If you still have trouble try the troubleshooting tips listed in the section Performing an Auto Approach for NC AFM imaging Setting Scan Parameters 1 Select a scan size scan rate number of data points per image and a fast scan dire
158. etween the tip and the sample Applying an electrostatic bias to the sample may be useful in situations that include the following Abrupt increases in the gradient of the van der Waals force and or the strength of the magnetic forces in the near field regime make obtaining an NC AFM image of a magnetic sample difficult The sign of the magnetic force for adjacent magnetic domains changes abruptly causing the tip to crash into the sample surface during MFM or NC AFM imaging For the first case applying a bias to the sample extends the tip to sample spacing regime in which a topography dependent force gradient term is dominant This gives you greater flexibility in obtaining a stable image of sample topography For the second case you need to apply a bias to the sample large enough to create a coulombic force term that is greater in magnitude than magnetic forces When this is the case the sign of the net force on the cantilever remains constant and the tip should not crash into the sample surface Variations in samples are wide enough that taking MFM images becomes a somewhat subjective iterative process Experience and familiarity with properties of specific samples enables you to obtain the best MFM images Hardware Components for Non ContactImaging 1 65 Hardware Components for Non Contact Imaging This section outlines how hardware components are involved in image production Brief descriptions of the function of e
159. eur definition Symbole Definition O Interrupteur d clench Equipement prot g par une isolation renforc e ou par une double isolation ZN Se r f rer a la documentation A Indique un risque de choc lectrique D finitions ATTENTION AVERTISSEMENT et REMARQUE Ces trois termes sont utilis s dans ce manuel d utilisation pour vous mettre en garde des probl mes li s la s curit lors de l utilisation de l AutoProbe CP ATTENTION AVERTISSEMENT ET REMARQUE Ces termes sont d finis dans le tableau 0 2 suivant Tableau 0 2 Description des termes Terme Description Attention Vous alerte des blessures s rieuses pouvant survenir dans le cas ou les proc dures d crites dans ce manuel ne sont pas suivies correctement N outrepassez pas un message de ce type si les conditions ne sont pas comprises et remplies Avertissement Vous met en garde des dommages possibles que le syst me pourrait subir ou des alt rations de s curit dans le cas ou les proc dures d crites dans ce manuel ne sont pas suivies correctement Remarque Vous met en garde des r gles suivre ou des conditions d utilisations particuli res Il est important que vous lisiez attentivement tous les messages Alerte Avertissement et Remarque de ce manuel afin de garantir les mesures de s curit mises en place pour l utilisation de votre syst me AutoProbe CP S curit lors de l utilisation xlvii R capi
160. f Warnings and Cautions s xi Grounding AutoProbe CP xiii setting the Line Voltages eon uee eieae E T E FT TE xiii Laser Safety Aa e a RN EE E EEE A A NET XV Specifications and Performance for AutoProbe CP xix ThermoMicroscopes Warranty Statement xxi Warranty on New Systems and Accessories uuesnesnnesnnesnensnensnennensnennnensennnnnnn xxi Warranty on Replacement Parts xxi Manufacturer Information ss xxii How to Use this Manual xxiii Vorwon EE SEEE S E EE N IV Betriebssicherheit 2 2 2 3 22 teen E een XXV Sicherheits Zeichen crs 58 ner ne MUR ins ne anne XXV Definitionen Warnung Vorsicht und Beachte uousnssesssenssneesnnn xxvi Zusammenfassung der Warnungen und Vorsichts u ccceesenesnnenn xxvii Erdung des AutoProbe VP2 ss XXix Einstellen der Versorgungsspannung ccssceeeceesseceeneecsseeceseeeeneecesreeeneeeees XXX Laser Sicherheit ssssssinenseraent hernie needs xxxi Spezifikationen und Ausf hrungen des AutoProbe CP S 00 0 cece eeeeeeereeeeeeeeeeeeees XXX VI ThermoMicroscopes Garantieerkl hrung 24022004000n00nnneennesnnesnnennennnennnenn XXXIX Garantie von neuen Systemen und Zubeh rteile XXXIX Garantie von Ersatzteilen XXXIX Hersteller Information issus mien ioe ec
161. fault value 2 Click to close the NCM Frequency Set dialog box and return to Move mode You have now set all of the NCM parameters You can also adjust the set point parameter during a scan from the Image mode window Since adjusting this parameter is equivalent to adjusting the tip to sample spacing it is commonly used to optimize the Topography signal trace Again the absolute value of the set point parameter corresponds to tip to sample spacing The absolute value of the default set point parameter and thus the tip to sample spacing corresponding to that set point value is too large for the system to detect sample topography In the next section you will perform an auto approach and then incrementally decrease the absolute value of the set point parameter bringing the tip closer to the sample until the sample topography is represented by the Topography signal trace and that signal trace is optimized As a reminder whenever you turn the probe head off and then back on again remember to first withdraw the tip from the sample to protect the tip When you turn the probe head back on before re approaching the sample a dialog box prompts you to set NCM parameters again Re setting NCM parameters means to re sweep the frequency response curve while the tip is far from the sample and re select a drive frequency The recommendation is made because the phase adjustment of the cantilever vibration signal may become unsynchronized while the
162. follow How the Scanner Works 6 3 How the Scanner Works The scanner is a tube made of a piezoelectric material which is a material that expands or contracts with applied voltage The scanner is a core component of a scanning probe microscope as it is used to move either a probe or a sample with extremely fine precision The line and pixel spacing of an image as well as the interaction between the tip and the sample are functions of the instrument s control over motion of the scanner Control of the scanner position depends on the predictability of the scanner s response to an applied voltage To first approximation this response is linear On the scale that applies for scanning probe microscope applications however the response exhibits nonlinearities These nonlinearities include hysteresis creep and aging If you have not already done so read Chapter 2 of A Practical Guide to Scanning Probe Microscopy a publication available through ThermoMicroscopes This will familiarize you with different types of scanner nonlinearities and their effects on images produced by a scanning probe microscope There are two approaches to improving the accuracy of scanner positioning One approach termed software correction uses software algorithms to predict a scanner s response to applied voltage The system calculates the voltages that should be sent to the scanner to achieve a desired scan size A second approach is called hardware correct
163. formationen ber die electrischen Eigenschaften von Oberfl chen Kapitel 6 Scanner Calibration beschreibt die Arbeitsweise des AutoProbe CP Scanners und die Kalibration des selben um eine optimale Funktion zu erhalten Abschnitt Ill Software Verweis Abschnitt III dieser Bedienungsanleitung Software Verweis ist ein Verweishandbuch f r ProScan Data Acquisition and Image Processing und schliesst Informationen ber folgenden AutoProbe Systeme ein CP LS and M5 Die Kapitel in diesem Abschnitt der Bedienungsanleitung vermitteln mehr detailierte Informationen ber die Softwareeigenschaften und steuerungen als die in den Schulungskapiteln vermittelten Informationen Der Aufbau der Kapitel erlaubt ihnen ein direktes Angehen der Eigenschaft oder der Steuerung mit welcher sie sich vertieft befassen m chten Kapitel 1 ProScan Data Acquisition beschreibt im Detail die Softwareeigenschaften von ProScan Data Acquisition Dieses Kapitel diskutiert jede Region des Bildschirms mit spezieller Beachtung jeder Steuerung und seiner Funktion Dieses Kapitel diskutiert auch die Menus mit einer Beschreibung jedes Menuelementes und seiner Funktion xliv Vorwort und bersicht Kapitel 2 ProScan Image Processing beschreibt im Detail die Softwareeigenschaften von ProScan Image Processing Dieses Kapitel erkl rt das Bearbeiten der Bilder wie Oberfl chenmessungen gemacht werden und wie Bilder vorbereitet werden um sie in unterschied
164. from the tip to maintain constant tunneling current Taking an STM Image 2 23 Typically the bias between the tip and the sample should be lower than about 1 voltin air If the bias is larger than about 1 volt the STM will not be operating in the tunneling regime The optimal bias to use depends on whether the sample is conducting or semiconducting With conducting samples you can use lower bias settings With semiconducting samples use higher bias settings as long as they are not much above 1 volt A typical bias range for STM is from about 0 1 to 1 V Constant Current vs Constant Height Mode You can take STM images in constant current mode or constant height mode These modes of STM operation are similar to the constant force and constant height modes for AFM images Constant current mode images are taken with feedback enabled and set to a moderate value The output signal from the feedback loop controls the z position of the scanner which extends or retracts to control the tip to sample spacing and maintain a constant tunneling current When the feedback parameters are optimized the scanner s z motion matches the sample s surface electronic structure The signal from the feedback loop that controls the scanner s z position called the Topography signal can then be used to generate an image of the sample surface This mode of imaging is often called constant current mode and it is the most common method of operating an STM
165. ge of focus If you are using the separate optical microscope for AutoProbe CP Position the fiber optic light source so that it shines directly down on the tip Place the microscope in the front of the probe head and adjust its position and focus so that you can see the tip clearly when you look through the objective lens You may need to move the Z stage and or the XY stages to bring the tip within the optics view and range of focus 8 When the tip is in focus and centered in the optical view use the coarse and fine focus knobs to focus on the sample surface 9 Move the tip down towards the sample using the z direction pad If you are using an AutoProbe CP with on axis optics view the tip by eye from the side as you lower the z tip Bring the tip to within a few millimeters of the sample surface If the sample surface is reflective you should be able to look at the TV monitor and see the reflection of the tip as the tip approaches the surface The reflection will appear to rise to meet the tip When you see the reflection let go of the z direction pad to stop moving Place the cursor close to the center line of the z direction pad and slowly bring the tip toward the sample When the tip and its reflection are almost touching let go of the z direction pad If the sample surface is non reflective you should be able to see the shadow of the tip Watch the tip approach close to the sample as you lower the tip using the z dire
166. ge mode window now accurately reflects the bias between the tip and the sample You should only need to check that this offset is valid periodically However you can expect the value to be different if you switch to a different probe head or scanner Note If you decide not to adjust the TipBiasVoltsOffset parameter value and there is an offset between the measured tip to sample bias and the bias set using the Taking an STM Image 2 17 system software then you must account for this offset when you set the sample and tip bias parameters for an STM scan For example if you measure an offset of 0 065 V and you wish to apply 500 mV between the tip and the sample then you need to enter 0 565 V for the tip bias if the sample is grounded You are now ready to start the tip to sample approach process Approaching the Sample To perform an auto approach you will first set selected scan parameters for the approach Then you will bring the tip close to the sample surface using the optical view Finally you will tell the system to perform an auto approach a process in which the tip and sample are brought together gradually until the set tunneling current value is detected Setting Up for an Auto Approach Two of the scan parameters you must set before performing an auto approach are the tunneling current and tip to sample bias The tip to sample bias was discussed in the previous section The tunneling current value is displayed as th
167. ge scans when x is the slow scan direction MicronPerDacSq_FastSY Calibrates additional scanner movement with voltage in y for large scans when y is the fast scan direction MicronPerDacSq_SlowSY Calibrates additional scanner movement with voltage in y for large scans when y is the slow scan direction Note Pay careful attention to the name of the calibration parameter you are selecting when you are changing a parameter s value The only difference between the Calibrating a 5 Micron Scanner 6 17 names of the first and second order calibration parameters is that the second order parameters include Sq in their names To determine values for the second order terms you must take another larger image of your calibration standard sample Taking an Image and Determining Calibration Parameter Values 1 If the probe head is not turned off turn it off now by either deselecting Head ON from the Mode menu or clicking the Head ON icon 2 Select High Voltage from the Mode menu 3 Turn on the probe head by selecting Head ON from the Mode menu or clicking the Head ON icon 4 From the Move mode window perform a coarse approach by using the z direction pad to lower the probe head until the tip is within a few millimeters of the sample surface Then click the button to initiate an auto approach 5 Switch to Image mode by clicking the Image Mode icon Y 6 Select a scan size that is
168. gen des Tastkopfes Die linke Warnungsmarkierung in Bild 0 2 oben stuft den Tastkopf als ein Klasse II Laserprodukt nach 21 CFR 1040 10 und 1040 11 ein Die Warnungsmarkierung in Bild 0 2 oben stuft den Tastkopf als ein Klasse 2 Laserprodukt nach EN60825 ein Bild 0 3 bis 0 7 unten bezeichnen die Orte aller Instrumentensteuerungen und Anzeiger im Zusammenhang der Laserbedienung des AutoProbe CP Systems Weiter werden auch die Orte der Lasersicherheitskennzeichnungen der Srahlen ffnungskennzeichnungen und der bereinstimmungskennzeichnungen angezeigt xxxii Vorwort und bersicht laser power laser laser on off switch position intensity video display Fe FE indicators indicators fasee beam steering screws dl gt green O O V prism PSPD 2 U sw up down G Of ka D PSPD forward backward i CAUTION LASER LIGHT DO NOT STARE INTO BEAM 0 2 mW AT 600 700 nm CLASS II LASER PRODUCT AVOID EXPOSURE LASER LIGHT IS EMITTED FROM THIS APERTURE n PER EN60825 1 1994 BILD 0 3 Ort der Lasersteuerung des Tastkopfes Die Steuerungen und Anzeigen bezeichnet in Bild 0 3 oben haben folgende Funktionen Laser power on off switch Schaltet den Laser des Tastkopfes ein oder aus Ein rotes Licht im Schalter leuchtet auf falls der Laser eingescchaltet ist Laser beam steering screws Die zwei Laserstrahl Steuerungsschrauben welche sich oben
169. ght closer to the sample surface as illustrated in Figure 1 7 These amplitude changes reflect the change in the force gradient acting on the cantilever which in turn reflects changes in the tip to sample spacing A feedback mechanism operates to maintain a constant cantilever vibration amplitude by adjusting and restoring the tip to sample spacing during a scan As in contact AFM mode the amount of scanner z movement necessary to maintain the tip to sample spacing i e to maintain a constant force gradient for the case of NC AFM is used to generate an image of topography 1 60 Chapter 1 NC AFM IC AFM and MFM Imaging How Intermittent Contact AFM Works The underlying principles for intermittent contact AFM are the same as those for non contact AFM The difference is that for IC AFM the cantilever is driven forced to vibrate at a fixed frequency close to but less than its free space resonant frequency as shown in Figure 1 8 Driving frequency change amplitude A 2 in resonant of vibration a lt frequency change N in vibration amplitude gt frequency Figure 1 8 Response curve for a cantilever for IC AFM mode showing an increase in vibration amplitude at the drive frequency for a decrease in cantilever resonant frequency Because the drive frequency is just below the free space resonant frequency the vibration amplitude of the cantilever increases as the cantilever is brought closer to the sample
170. gnal accentuates edges of magnetic domains on an image and thus may help you to distinguish these domains Taking anMFM Image 1 45 The MFM Amplitude signal is the input signal to the feedback loop analogous to the probe signal representing cantilever deflection in contact AFM mode By comparison the Topography signal is the signal sent to the scanner to maintain a constant cantilever oscillation amplitude The Topography signal is produced by taking the Error signal which is the difference between the MFM Amplitude signal and the set point and sending it through feedback electronics which include proportional and integral amplifiers When you take an MFM image using the Topography signal you set the gain so that the system tracks changes in the force gradient For vibrating cantilever methods the Topography signal is used to take images that are analogous to constant force mode images in contact AFM mode When you take an MFM image using the MFM Amplitude signal you set the gain to a low value so that the system s feedback electronics do not track changes in the force gradient closely These changes in the force gradient are then reflected by changes in the MFM Amplitude signal and an image of magnetic features on the sample surface is produced Taking an MFM image using the MFM Amplitude signal is analogous to constant height mode imaging in contact AFM mode As such the MFM Amplitude signal can be useful for taking images
171. gnal trace on the Oscilloscope Display try the following methods to remove them Reduce the gain parameter Try this first Move the tip further away from the surface by increasing the absolute value of the set point parameter i e make the set point more negative Reduce the drive amplitude the drive parameter Taking an NC AFM Image 1 25 3 Then to improve surface tracking try making small adjustments to increase the gain or vary the set point value incrementally until the signal trace is optimized Reducing the scan rate can also improve surface tracking Adjusting the X and Y Slope If you are taking an image and the x direction is set to be the fast scan direction then adjusting the slope parameter in Image mode adjusts the x slope Ifthe y direction is set to be the fast scan direction then adjusting the slope adjusts the y slope You can adjust both the x and y slopes of an image by using the x and y option buttons to toggle the fast scan direction between x and y and adjusting the slope parameter for each direction 1 While looking at the Topography signal trace on the Oscilloscope Display adjust the slope parameter to make sure that the signal trace is level Starting a Scan After you have set and or adjusted the scan parameters listed in the previous sections so that the Topography signal trace in the Oscilloscope Display is stable and repeatable start taking an image 1 Click the button below the
172. gnetic not topographic features on the sample surface and to make sure that the system tracks the set point value closely To operate with a higher gain value do the following 3 Back the tip away from the sample by increasing the absolute value of the set point parameter 4 Increase the gain from its default value to a higher value For example set the gain to 5 5 Next decrease the absolute value of the set point parameter incrementally as you did before Since the gain is set to a higher value if oscillations appear they should be more pronounced It should be easier to identify the regime where the van der Waals force gradient begins to dominate the magnetic force gradient 1 44 Chapter 1 NC AFM IC AFM and MFM Imaging 6 Experiment with the gain parameter checking to see if the features shown on the signal trace change depending on the gain value Choose a gain value that generates a signal trace representing magnetic information only with no superposition of topographic information As you adjust the gain you can also monitor the Probe Signal bar displayed underneath the Toolbar The yellow band on the Probe Signal bar represents the probe signal as it varies about the set point value which is represented by the red line Higher gain values tend to tighten the excursion of the probe signal from the set point value since the system tracks the set point more closely This tightening of the probe signal about the
173. gr sserung Zus tzliche akustische Isolationskammer 20 bit DACs f r x y und z Achsen 16 bit DACs f r System berwachung 100 MHz Pentium Prozessor 256 Kbyte Cachespeicher 16 MB RAM 1 GB Hard Drive 3 1 2 in 1 4 MB Floppydisk Drive ProScan Data Acquisition und Image Processing arbeitets mit Windows 95 Windows Graphikbeschleuniger 17 in hochaufl sender Farbmonitor 115 230 V AC 50 60 Hz 600 W 10 5 in 267 mm x 8 in 203 mm 22 Ib 10 kg 17 in 432 mm x 7 1 2 in 191 mm x 17 1 2 in 445 mm 43 Ib 20 kg 17 in 432 mm x 7 1 2 in 191 mm x 17 1 2 in 445 mm 27 lb 12 kg 0 C bis 30 C 32 F bis 112 F 90 nicht kondensierend Isopropylalkohol Isopropylalkohol Isopropylalkohol xxxviiiV orwort und bersicht WARNUNG Um eine Ber hrungsgefahr zu vermeiden sollen w hrend dem Reinigen der AutoProbe CP Systemkomponenten diese immer ausgeschaltet sein VORSICHT Es sollte kein Aceton verwendet werden um die Komponenten des AutoProbe CP Systems zu reinigen da dabei wichtige Sicherheits Warnungs Etiketten von den Komponenten losgel st werden k nnten ber den Gebrauch des Benutzerhandbuches xxxix ThermoMicroscopes Garantieerkl hrung Garantie von neuen Systemen und Zubeh rteile ThermoMicroscopes garantiert dem Orginalk ufer des Ger tes das dieses frei von Material und Verarbeitungsfehlern ist Diese Garantie gilt f r ein Jahr ab dem Lieferdatum ThermoMicr
174. hapter 5 l V Spectroscopy 5 2 Chapter5 l V Spectroscopy Introduction This chapter describes how to generate current vs voltage I V curves to study electronic properties at specific x y locations on a sample surface A current vs voltage curve is a plot of the tunneling current as a function of the bias voltage that is applied to the sample Up to sixteen current vs voltage curves can be generated for each STM image you acquire using the I V Spectroscopy feature of Data Acquisition In this chapter you will find information on the following topics understanding the controls in I V Spectroscopy generating a current vs voltage curve and a dI dV curve adjusting parameters and zooming in on features of a curve adjusting the horizontal and vertical scales of a current vs voltage or dI dV curve making point to point measurements on a current vs voltage or dI dV curve saving and exporting current vs voltage data retrieving previously saved current vs voltages or dI dV curves This tutorial will give you the basic knowledge you need to generate current vs voltage curves The curves provide important information about the local electronic properties of your sample The l V Spectroscopy Window 5 3 The I V Spectroscopy Window Current vs voltage I V curves are acquired using Spectroscopy mode of ProScan s Data Acquisition software You can open the I V Spectroscopy window by selecting
175. he Calibration Values textbox of the Manual Calibration Entry dialog box as described in an earlier section This section also gives the dimensions of available cantilevers as well as their theoretical resonance frequencies Microlevers Microlevers microfabricated from low stress silicon nitride are highly resilient with a wide range of force constants from 0 5 to 0 01 N m Microlevers are available with standard or sharpened integrated pyramidal tips with nominal radii of less than 500 A and 200 A respectively Each Microlever chip has five V shaped cantilevers and one rectangular cantilever A top view and a close up view of a Microlever chip are shown below e A A amp 35 3m W JA L standard tip E 0 6 E mm o ca 1 0 mm m Lw TUVS 1 6 5 6 mm B D sharpened tip Figure 4 7 Microlever chips hold six cantilevers Typical radius of curvature is 500 A for standard tips and 200 A for sharpened tips Force Resonance Thickness constant frequency L W um N m kHz Type um um A iso 18 060 005 mn B 20 0 06 002 5 c 320 2 060 00 7 E D 20 2 0607 008 15 EE AO 06 20005 ss Bs r 85 718 06 0 50 120 4 32 Chapter 4 Force vs Distance Ultralevers Ultralevers are gold coated all silicon cantilevers with integrated high aspect ratio conical tips The typical radiu
176. he cantilever Cantilever deflection away from the surface is the result of a net positive force on the cantilever Fy gt F Cantilever deflection toward the surface is the result of a net negative force on the cantilever Fy lt Fc Figure 4 4 shows the effects of positive and negative net forces on cantilever bending Figure 4 5 shows an interatomic force vs distance curve which is a plot of the force acting between the tip and the sample as a function of tip to sample spacing The interatomic force vs distance curve is similar to the Lennard Jones curve of the potential energy between atoms as a function of distance Looking at the curve you can see two regimes where an atomic force microscope is operated the non contact and contact regimes 4 28 Chapter 4 Force vs Distance force repulsive force fT contact Distance tip to sample separation NZ attractive force Non contact Figure 4 5 Interatomic force vs distance curve Figure 4 5 shows that when the tip to sample spacing is large the force between the tip and the sample is attractive A non contact atomic force microscope NC AFM is operated within this range of forces where the total net force on the cantilever is negative As the tip approaches the sample the force between atoms on the tip and atoms on the sample eventually becomes repulsive When the cantilever tip is in contact with the sample in the absence of liquid layers on
177. he far field regime In the far field regime the gradient of the van der Waals force is negligible and an image taken using the Topography signal represents variations in the gradient of the magnetic force Using an Electrostatic Bias An electrostatic bias applied to the sample is sometimes used during MFM imaging to stabilize the signal trace and obtain images of either magnetic or topographic features on your sample s surface This section shows how an applied electrostatic bias affects the interatomic force vs distance curve for a magnetized tip and sample When you apply a non zero bias to a sample that is dielectrically homogeneous charge is distributed evenly over the surface A coulombic force F is created between the tip and the sample The absolute value of this coulombic force is much greater than that of the van der Waals force which becomes negligible The net force and force gradient between the tip and the sample become the following F Fm Fe 5 dF dz dF dz dFe dz 6 Figure 1 10 illustrates the coulombic force term on a force vs distance curve 1 64 Chapter 1 NC AFM IC AFM and MFM Imaging Force F Fm repulsive Near field 7 BE gt Fm attractive d tance 2 F applied bias Figure 1 10 Interatomic force vs distance curve showing magnetic F m and coulombic Fc force terms The magnitude of the coulombic term depends on the magnitude of the bias applied b
178. he scanner is to determine values for the first order calibration parameters for the two scan directions x and y Two values need to be determined for each scan direction one for each direction when it is the fast scan direction and one for each direction when it is the slow scan direction There are thus four first order scanner calibration parameters Once you determine and enter values for the four first order scanner calibration parameters the accuracy of small scan sizes improves 6 6 Chapter 6 Scanner Calibration For larger scan sizes greater than roughly 1 um the relationship between the scanner s position and the voltage applied to the scanner becomes nonlinear The software adds second order terms to the description of the scanner s response to applied voltage that is used to produce the desired scan size There are four second order calibration parameters one for each direction when it is the fast scan direction and one for each direction when it is the slow scan direction Once you determine and enter non zero values for the second order calibration parameters the accuracy of scan sizes for larger images improves Note While calibrating a 5 um scanner improves the accuracy of scan sizes you may still see the spacing of features on an image vary with distance for large scan sizes Values for all of the calibration parameters are determined manually The procedure involves making measurements on an image of a ca
179. he software to measure the distance between three maxima along the x axis and it produces a value of 1 5 um and the existing MicronPerDac_FastSX value is 2 5 then the correct value of the calibration parameter is calculated as follows MicronPerDac_FastSX 2 5 x n 3 33 Record the correct value in the high voltage column of your table of calibration values Repeat Steps 10 through 12 measuring the spacing between maxima along the y axis of the fast x image Record a value for the MicronPerDac_SlowSY parameter Next switch the fast scan direction to be the y direction Again correct the slope parameter so that the signal trace on the Oscilloscope Display is level The scan rate and scan size should be left the same Click the button to take an image with the y direction as the fast scan direction Repeat steps 10 through 12 measuring the distance between maxima in the y direction of the fast y image to calculate a value for the MicronPerDac_FastSY parameter Repeat steps 10 through 12 measuring the distance between maxima in the x direction of the fast y image to calculate a value for the MicronPerDac_SlowSX parameter You should now have values recorded in your table for all four of the first order scanner calibration parameters for high voltage mode Next you will enter the corrected values of the first order scanner calibration parameters into the scanner calibration file Editing the Scanner Calibration Fi
180. his graphically by defining a region of interest on the curve Or you can zoom in by reducing the limits of the voltage sweep range Details of zooming in on an I V curve are described in two sections that follow Zooming in Graphically Using the Cursor To zoom in on a portion of an I V curve you can use the cursor to define a region of interest on the graph as follows 1 Click the button to generate an I V curve to zoom in on 2 Click the Zoom option button to set the cursor function as a zoom box tool 3 Select a portion of the I V curve by dragging a box around it with the cursor A black box shows up on the graph 4 To prompt the software to zoom in on the region inside the box click the button The I V curve displayed on the graph changes to reflect the zoom in area The resolution of the data remains the same When you resume data acquisition by clicking the button again the range of data acquisition is re selected to match the zoom in region Since the same number of data points 1000 per curve are taken over a smaller range the resolution of the resulting I V curve increases 5 Click the button again to start sweeping the voltage range once again The voltage limits over which data are acquired will be those defined by the cursor s zoom box Zooming in by Changing the Voltage Sweep Range To zoom in by decreasing the voltage sweep range follow these steps 1 Click the button to generate an I V curve that
181. ies ThermoMicroscopes warrants to the original purchaser of the equipment that the equipment will be free from defects in material and workmanship for a period of one year from date of delivery ThermoMicroscopes agrees as its sole responsibility under this limited warranty that it will replace or repair at its option the warranted equipment at no charge to the purchaser and will perform services either at ThermoMicroscopes s facility or at the customers facility at ThermoMicroscopes s option For repairs performed at ThermoMicroscopes s facility the customer must contact ThermoMicroscopes in advance for authorization to return the equipment and must follow ThermoMicroscopes s shipping instructions If returned the equipment must be insured ThermoMicroscopes will supply replacement parts on loan whenever possible to enable field repair by customers with minimum downtime once the system is operational the defective parts are then returned to ThermoMicroscopes Specifically excluded from this warranty are all consumable parts including but not limited to Microlevers Ultralevers and tips The warranty of equipment sold for use outside the United States depends on the condition of each sale Equipment which has been subjected to misuse accident abuse disaster unreasonable use damage caused by third party systems with which the equipment is used operational error neglect unauthorized repair alteration or installation is n
182. ignal is saturating for data collection in one direction of scanner motion only try adjusting the vertical position of the PSPD slightly This alignment can be performed while the tip and sample are in contact If the LFM signal is saturating for data collection in both directions of scanner motion try lowering the set point value This reduces the force on the cantilever If lowering the set point value does not work then you may need to switch to a stiffer cantilever Once you have successfully taken an LFM image of the gold grating sample you can practice varying scan parameters and comparing AFM and LFM images If you like you can try switching to a different sample to see variations in its topography and frictional properties Summary 3 19 Summary This chapter covered the following information related to operation of your AutoProbe CP instrument in LFM mode how the LFM cantilever detection scheme works how LFM images correlate with sample surface features how to compare and interpret LFM and AFM images how to take simultaneous LFM and AFM images Once you are familiar with the background materials and instrument setup procedures that are covered in this chapter you should be ready to take AFM LFM images of more complicated samples that reveal subtle features of LFM operation 3 20 Chapter 3 LFM Imaging Chapter 4 Force vs Distance 4 2 Chapter 4 Force vs Distance Introduction Thi
183. ils conducteurs emm l s d connect s ou endommag s doivent imm diatement tre signal s l quipe de support technique de ThermoMicroscopes Ne pas utiliser l AutoProbe CP lorsque les fils conducteurs sont emm l s d connect s ou endommag s xlviii Preface and Overview AVERTISSEMENT Tous les composants du syst me AutoProbe M5 doivent tre manipul s avec pr caution Les composants du syst me contiennent une instrumentation lectrom canique d licate qui peut facilement tre endommag e par de mauvaises manipulations AVERTISSEMENT Le courant du AEM doit tre coup position OFF avant d enlever ou d installer le scanner AVERTISSEMENT L interrupteur laser ON OFF de la t te du microscope doit tre en position OFF avant de retirer ou d installer la t te du microscope sur l tage de translation en XY Dans le cas contraire des dommages aux diodes lectroluminescentes de la t te du microscope LEDs peuvent survenir AVERTISSEMENT En retirant et en installant le scanner vous devez tre mis la terre l aide d un bracelet conducteur vous reliant la terre pour vous assurez que le scanner n est pas endommag Le scanner est sensible aux d charges lectrostatiques AVERTISSEMENT Les quatres vis qui connectent le scanner l unit de base du CP doivent tre serr es proprement pour assurer une mise terre correcte Lorsque les quatres vis
184. ing 1 2 Chapterl NC AFM IC AFM and MFM Imaging Introduction This chapter describes three atomic force microscopy AFM modes of AutoProbe operation that use a vibrating cantilever Non Contact AFM NC AFM Intermittent Contact AFM IC AFM Magnetic Force Microscopy MFM The information in this chapter applies to both standard and multitask AutoProbe CP system configurations NC AFM and IC AFM operating modes are standard with the multitask configuration and they are available as options with the standard configuration MFM requires magnetically coated cantilevers which are part of a separate MFM toolkit Following brief sections that describe vibrating cantilever AFM methods and components required for these methods three tutorial sections take you step by step through obtaining an NC AFM image an IC AFM image and an MFM image Then if you are interested in learning more about how vibrating cantilever methods work you can refer to three sections at the end of this chapter How Non Contact AFM Works How Intermittent Contact AFM Works and How Magnetic Force Microscopy Works These sections describe the underlying principles of each imaging technique In addition you can refer to the section Hardware Components for Non Contact Imaging at the end of the chapter for a description of the hardware components involved in image production Vibrating Cantilever AFM Methods 1 3 Vibrating Cantilever A
185. ing the button Acquiring Force vs Distance Data 4 11 The next section describes how to calibrate the vertical axis of the F vs d graph with units of force You can skip this section if you have already performed the calibration procedure for the cantilever you are using Calibrating the Vertical F vs d Axis This section describes how to calibrate the vertical axis of the F vs d graph with units of force This procedure is important if it is not performed then the units of the vertical axis do not correlate correctly with force You must perform this calibration procedure any time you switch to a different cantilever However the system remembers the calibration results so you do not need to repeat the procedure even if you exit ProScan software If you have already performed the procedure for the cantilever you are using you can skip to the section Generating a Force vs Distance Curve later in this chapter The calibration procedure involves taking an F vs d curve using a hard sample such as the calibration grating provided with your system Using a hard sample ensures that the mechanical properties of the sample do not couple with those of the cantilever and affect the calibration The procedure involves three general steps 1 Check or enter the value of the cantilever force constant 2 Acquire a F vs d curve 3 Run an automated procedure that performs the calibration These general steps are described in
186. ion in which detectors and feedback loops are used to measure and correct the position of a scanner to achieve a desired raster pattern as well as scan size If you are using a 5 um scanner with your AutoProbe CP instrument then your system is equipped with software correction You need to calibrate the response of the scanner tube with applied voltage If you are using a 100 um scanner with your AutoProbe CP instrument then your system is equipped with both software and hardware correction the ThermoMicroscopes s hardware correction system called ScanMaster includes detectors that you must calibrate first Then your system uses the calibrated detectors to automatically calibrate the response of the scanner tube to applied voltages The next section explains when you should perform scanner calibration procedures 6 4 Chapter6 Scanner Calibration When to Calibrate the Scanner When you purchase an AutoProbe instrument the scanner s you receive arrives pre calibrated In other words the system software contains calibration parameter files for all of the scanners and those files contain default values for the scanner calibration parameters The default values reflect the characteristics of each scanner for standard testing conditions There are however three main reasons why you should know how to calibrate the scanner 1 The scanner calibration procedure is a method for checking that the scanner is in good conditio
187. ions effectu es par ThermoMicroscopes le client doit demander l avance une autorisation d exp dition de mat riel ThermoMicroscopes RMA et suivre la proc dure ThermoMicroscopes d exp dition Le mat riel renvoy doit tre assur par l exp diteur ThermoMicroscopes fourni en pr t dans la mesure du possible des pi ces de remplacement pour permettre au client une r paration sur site dans les meilleurs d lais Une fois le syst me op rationnel les pi ces d fectueuses doivent tre envoy es chez ThermoMicroscopes sans d lai Sont exclus entre autre de cette garantie tout les consommables tels que Microlevers Ultralevers et les pointes STM La garantie des quipements vendus pour une utilisation en dehors des Etats Unis d pend des conditions de garantie sp cifi es lors de la vente Le mat riel qui aurait t soumis un mauvais traitement emploi un accident une catastrophe une utilisation inappropri e qui aurait subi des dommages provoqu s par un quipement non fournis avec le syst me une erreur d utilisation une modification une r paration ou installation non autoris e ne sont pas couverts par la garantie Garantie des pi ces remplac es ThermoMicroscopes ThermoMicroscopes garanti toutes les pi ces de remplacement pendant une dur e de 90 jours partir de la date de livraison contre les d fauts de mat riel ou de fabrication ThermoMicroscopes remplacera ou r parera sel
188. ip and the probe head As you view the head from above place one probe of the multimeter on the rear left brass screw of the head which connects to the metal contact pad of the STM cartridge Place the other probe of the multimeter on the metal cylinder of the STM cartridge which has a hole that holds the STM tip wire The resistance between the probe head and the tip should be small for STM operation Note If the STM cartridge is too loose or too tight the conducting path may be disrupted Try adjusting the position of the probe cartridge to establish good contact If this does not help call ThermoMicroscopes Customer Support for help in diagnosing the problem Next you will check the voltage drop between the tip and the sample The measured voltage should correspond to the voltage difference that you set using the system software 2 Click the Head ON icon to turn the power to the probe head on 3 Switch to Image mode by clicking the Image Mode icon Y 2 16 Chapter2 STM Imaging Check the values of the sample bias and tip bias parameters listed in scrollboxes of Image mode The default values of these parameters should be zero Leave the sample bias value at zero so that the sample is grounded and set the tip bias at 1 V Use the multimeter on the Volts setting to measure the voltage drop between the tip and the sample Make the measurement quickly the finite impedance of the voltmeter pr
189. is chapter explains how to process images how to make surface measurements and how to prepare images for printout in a variety of formats Vorwort Betriebssicherheit Dieses Kapitel enth lt wichtige Informationen ber ihr AutoProbe CP System Es beschreibt im Detail den Arbeitsablauf in Bezug auf die Betriebssicherheit des AutoProbe CP und muss daher vollst ndig durchgelesen werden bevor sie ihr AutoProbe CP System bedienen WARNUNG Der durch das AutoProbe CP System versehene Schutz ist beeintr chtigt falls die in diesem Benutzerhandbuch beschriebenen Arbeitsabl ufe nicht genaustens befolgt werden Sicherheits Zeichen In Tabelle 0 1 sind die im Benutzerhandbuch und auf dem AutoProbe CP System vorkommenden Zeichen aufgelistet Sie sollten mit der Wirkung der Zeichen vertraut werden in welcher Weise sie mit der Betriebssicherheit des AutoProbe CP in Zusammnehang stehen Tabelle 0 1 Sicherheits Zeichen und ihre Wirkung Zeichen Wirkung MEERE Gleichstromquelle gt Wechselstromquelle FN Wechselstrom und Gleichstromquelle PNA Dreiphasenstromquelle Je Erdungsanschluss amp Schutzerdungsanschluss 77 Geh use oder Rahmenanschluss Y quipotentialanzeige Schaltet Stromversorgung ein xxvi Vorwort und bersicht Tabelle 0 1 Fortsetzung Sicherheits Zeichenund ihre Wirkung Zeichen Wirkung O Schaltet Stromversorgung aus Bezeichnet doppelte oder verst rkte Is
190. is labeled AFM NC AFM to distinguish it from other probe heads you may have A connector on the rear of the probe head plugs into a connector on the back of the translation stage 1 10 Chapter 1 NC AFM IC AFM and MFM Imaging If you have the multitask AutoProbe CP system configuration Install the multitask probe head and set the two mode switches on the probe head to the AFM and NC AFM positions 2 Once the probe head is installed turn the LASER ON OFF switch to the ON position 3 Insert a non contact chip carrier onto the non contact cartridge The procedure for inserting a chip carrier is the same as for contact mode AFM Refer to Part I of this User s Guide for detailed instructions if needed Installing an NC AFM chip carrier involves selecting a cantilever Cantilevers best suited for NC AFM imaging have the following properties Sharp tip High stiffness Well defined resonant frequencies Use non contact chip carriers with NC AFM Ultralevers 4 Insert the non contact cartridge in the probe head as described in Part I of this User s Guide Configuring the Software Turn on the instrument and open ProScan Data Acquisition by completing the following steps 1 Turn on the AEM The on off button is located on the rear panel of the module 2 Turn on the color video monitor The on off button is located on the front of the monitor below the screen 3 Turn the computer and the monitor on The compute
191. is not checked as part of the auto approach process However if it is closer to zero then the system will be able to accommodate a greater range of lateral deflection of the cantilever during the LFM scan To check the vertical alignment of the PSPD Adjust the up down screw to move the PSPD so that the left and right indicator lights are both off This adjustment centers the laser spot between the A B and C D or upper and lower halves of the PSPD When the left and right lights are both off the LFM signal A B C D should be small ILFMI lt 300 mV This signal represents the lateral deflection of the cantilever To check the value of the LFM signal open a Digital Voltmeter DVM by clicking the DVM icon E Click the button on the DVM window to see a selection of channels or signals Click More to see more signals and then select LFM The display of the DVM will show the value of the LFM signal given in volts or millivolts depending on the value If the DVM shows that the absolute value of the LFM signal is greater than 300 mV then adjust the up down screw to move the PSPD until the absolute value of the LFM signal is less than 300 mV The laser spot should now be centered between the A B and C D halves of the PSPD Once you have aligned the deflection sensor and successfully approached a sample you are ready to take an image CAUTION If you want to turn off the probe head after you have performed an
192. ith a lid with the sharp tip pointing up Close the lid of the container To remove a tip from the STM cartridge First loosen the set screw on the cartridge Then grip either end of the tip with a pair of needle nose pliers and pull the wire out of the hole WARNING STM tips are very sharp Be careful when handling an STM cartridge with a tip loaded Avoid leaving the STM cartridge on a table or other work surface with the exposed tip pointing up Store the STM cartridge and tip in a container with a lid 2 12 Chapter 2 STM Imaging Taking an STM Image This section describes how to take an STM image using AutoProbe CP While STM mode is often used for taking images with atomic resolution this type of imaging can be difficult for instruments operating in air since an STM is highly sensitive to surface contaminants and water layers STM can be used to image metals and also semiconductors without insulating oxide layers For example STM images can be taken of gold graphite and semiconducting oxides STM cannot be used to look at insulating samples for instance Aly03 because no tunneling current will flow between the tip and an insulating sample Since no tunneling current is detected the tip will crash into the sample surface during an auto approach Two examples of samples that can be used to demonstrate the capabilities of an STM operating in air are a calibration grating such as the 1 um gold grating provided
193. kHz f 96260 Hz 5kHz div Zoom In Zoom Out Refresh Done Help Figure 1 5 Response curve for a typical IC AFM cantilever with the horizontal scale expanded by the zoom in operation Taking an IC AFM Image 1 31 Selecting an Imaging Amplitude The imaging amplitude represented by the set point parameter is the amplitude of cantilever vibration that the z feedback loop tries to attain during an auto approach and to maintain during a scan The system s feedback loop is designed for non contact imaging the system expects the amplitude of cantilever vibration to decrease with decreasing tip to sample spacing and so smaller absolute values of the set point parameter cause the scanner to extend However for IC AFM since the drive frequency lies on the left side of the resonance peak the amplitude of cantilever vibration increases as the tip is brought closer to the sample See the section How Intermittent Contact AFM Works at the end of this chapter for details Thus to operate in IC AFM mode you decrease the absolute value of the set point until intermittent contact between the tip and the sample is achieved Because of the damping effects of contact between the tip and the sample the amplitude of cantilever vibration decreases after intermittent contact is made and the set point value is matched You can adjust the set point parameter graphically in the NCM dialog box It is rep
194. king an Image and Determining a Calibration Parameter Value for the scanner sensitivity in z This time enter the value in the Low Voltage column of your table of calibration parameters 3 Follow Steps 1 through 7 of the previous section Editing the Scanner Calibration File to edit the value of the MicronPerDac_SZ calibration parameter for low voltage mode The scanner sensitivity calibration parameter for the z direction is now calibrated for both high and low voltage modes Creating a Backup Scanner Calibration File If you have completed the instructions of this section then you have calibrated your 5 um scanner and thus created a new calibration parameter file Saving a backup copy of this file involves the following general procedures 1 Create a special directory c scancal for backup files 2 Create backup copies of the current scanner calibration parameter files and store them in c scancal Each time you perform a scanner calibration you automatically update the working scanner calibration parameter file You should update the backup copy of this file in the c scancal directory at the same time in case the working file becomes corrupted The above listed general procedures for file management are broken into detailed steps below The directions assume you are using Windows 95 1 Create the c scancal directory a From the Start menu point to Programs and select Explorer Open the c drive b
195. le 3 Set up to take a follow up NC AFM image as described in the previous section Taking Follow Up Images of Sample Topography If you are having trouble obtaining a signal trace that is stable repeatable and representative of sample topography try applying a bias to the sample 4 Use the Sample Bias scrollbox to select a non zero value for the Sample Bias parameter Start by entering a moderate value for example 0 5 V Press the Enter key so that the software recognizes the change 5 Monitor the Topography signal trace on the Oscilloscope Display to see the effect of the sample bias If there is no effect use the Sample Bias scrollbox arrows or enter a new value to change the Sample Bias until you see an effect 6 If you are able to obtain a stable Topography signal trace that begins to show topographic features increase the bias until the Topography signal stops improving At this point try increasing the gain parameter and decreasing the set point parameter iteratively while making minor adjustments to the Sample Bias if necessary Continue iterative adjustment of the Sample Bias set point and gain parameters until the Topography signal trace is optimized If you increase the Sample Bias too much the Topography signal may become smooth losing resolution Smoothing occurs because as you increase the Sample Bias the force gradient experienced by the cantilever increases and the system increases the tip to
196. le Switch to Move mode and use the z direction pad to raise the probe head so that the tip is a safe distance from the sample Turn off the probe head by either deselecting Head ON from the Mode menu or clicking the Head ON icon 10 Calibrating a5 Micron Scanner 6 15 Select Calibration Edit from the Setup menu Click in the Warning box to indicate that you want to proceed Select the Scanner category in the left listbox Select a first order calibration parameter whose value you would like to change For example select MicronPerDac_FastSX Change the value of the parameter by typing the new value into the textbox above the Calibration Values listbox Be sure to press the Enter key after entering the new value so that the correction is recognized by the software Repeat Steps 5 and 6 for all of the first order scanner calibration values that you wish to change Now set the values of all four of the second order calibration parameters to zero The names of the second order calibration parameters are as follows MicronPerDacSq_FastSX MicronPerDacSq SlowSX MicronPerDacSq_FastSY and MicronPerDacSq_SlowSY Note that the names are identical to their first order counterparts except for the inclusion of Sq If the value of any of these parameters is listed as Invalid then the system will not disable the default first order calibration parameters and the calibrated first order values you
197. librating force with volts 14 Using the mouse position the cursor at one end of the linear portion of the F vs d curve Click the LEFT mouse button to select this first point A cross on the graph indicates the location you selected 15 Again using the mouse position the cursor at the other end of the linear portion of the F vs d curve Try to include a long portion of the linear part of the curve that will allow the system to accurately calculate a slope value Click the RIGHT mouse button to select the second point A second cross smaller than the first appears on the graph indicating the location you selected 16 Click the button This prompts the system to compute and save the calibration coefficient The Cal Sweep box is deselected and the button is disabled The calibration procedure is complete The vertical axis is calibrated with force for all subsequent F vs d curves you take using this cantilever Note Be sure to repeat the calibration procedure any time you switch to a different cantilever Generating a Force vs Distance Curve This section describes how to acquire an F vs d curve for general samples It assumes you have already performed the calibration procedure described in the previous section 1 Take a contact AFM image as you normally do using the sample whose mechanical properties you wish to study using F vs d spectroscopy Specifically follow Steps through 8 of the earlier section Taking a
198. libration sample to determine new values for the calibration parameters The parameters are stored in calibration parameter files in ProScan s calibration database They are accessible to the user from within the ProScan Data Acquisition program The next section Scanner Calibration Procedures takes you step by step through the scanner calibration procedures Scanner Calibration Procedures The procedures of this section describe calibration of a5 um scanner The sequence of the procedures is as follows setting up the system for scanner calibration first order calibration of scanner sensitivity inx and y second order calibration of scanner sensitivity inx and y calibration of scanner sensitivity in z After you have determined values for each set of parameters you will learn about how to access scanner calibration parameters in the software and how to change their values Calibrating a5 Micron Scanner 6 7 Setting Up the System This section assumes that your instrument has been installed by a ThermoMicroscopes representative all of the cables are properly connected and you have completed the tutorial chapters in Part I of this User s Guide It also assumes you are using a5 um scanner In addition to calibrate a 5 um scanner you will need a calibration sample A calibration sample has periodic features of known spacing The calibration sample you choose depends on the image size you expect to use most fre
199. lichen Formaten auszudrucken S curit lors de l utilisation xlv Pr face S curit lors de l utilisation Ce chapitre comprend des informations importantes propos de votre syst me AutoProbe CP Les proc dures relatives la s curit lors de l utilisation de l AutoProbe CP y sont d crites et par cons quent doivent tre lues scrupuleusement avant toute mise en route de votre syst me AutoProbe CP ATTENTION Les protections pr vues par le syst me pourraient tre inefficaces si les proc dures d crites dans ce manuel ne sont pas suivies scrupuleusement Symboles de s curit Le tableau 0 1 pr sente les symboles utilis s tout au long de ce manuel d utilisation ainsi que sur le syst me AutoProbe CP Vous devrez vous familiariser avec leurs symboles et d finitions car elles sont utilis es pour vous mettre en garde des probl mes li s la s curit lors de l utilisation de l AutoProbe CP Tableau 0 1 Symboles de s curit et leur d finition Symbole D finition ee Source de courant continu EZ Source de courant alternatif ENG Source de courant alternatif avec une composante continue N Source de courant alternatif triphas Jr Borne de mise la masse terre L Borne conductrice isol e 777 Borne connect e au ch ssis ou la structure g Indique un niveau quipotentiel Interrupteur enclench xlvi Preface and Overview Table 0 1 suite Symboles de s curit et l
200. lick the button to generate an F vs d curve to zoom in on Adjust parameters if necessary and then click the button 2 Click the Zoom option button to set the cursor function as a zoom box tool 3 Select a portion of the F vs d curve by dragging a box around it with the cursor The F vs d curve displayed on the graph changes immediately to reflect the zoomed in area As mentioned above the resolution of the data remains the same When you resume data acquisition by either clicking or the scanner s sweep range remains the same but the portion of that range over which data are collected or read is re selected to match the zoomed in area and the resolution of the data increases accordingly Note If you are plotting the Z Detector signal along the horizontal axis you may notice on the zoomed in curve that the portion of either the extension or the retraction path of the F vs d curve differs from the portion you selected This phenomenon is a result of scanner hysteresis If you choose to plot the Z Detector signal you can use the Zoom Priority feature of the Spectroscopy Setup dialog box to ensure that the portion of either the extension or the retraction path of subsequent zoomed in curves is consistent with the portion you select on the original curve Selecting Snap In ensures that the extension path is consistent Selecting Snap Out ensures that the retraction path is consistent Acquiring Force vs Distance Data 4 21 4
201. m scanner Therefore this section applies if you have an AutoProbe CP multitask instrument or if you have purchased a 100 um scanner for a standard AutoProbe CP instrument This section is divided into three subsections which cover the following topics how ScanMaster works what it means to calibrate the scanner scanner calibration procedures The first two sections provide background information that may be useful to you as you perform the scanner calibration procedures If you would like however you may skip directly to the section that describes how to calibrate a 100 um scanner How ScanMaster Works If you are using a 100 um scanner then your system is equipped with ScanMaster ScanMaster is a hardware solution that addresses the problems of nonlinearity intrinsic to a piezoelectric scanner Position sensitive photodetectors PSPD s and light emitting diodes LED s are used to monitor the position of the scanner tube in the x y and z directions Both the response of the detectors and the response of the scanner tube to applied voltage must be calibrated for systems that are equipped with ScanMaster The detectors are mounted on the scanner tube and therefore move with the tube The LED s are located inside the scanner housing and remain stationary An LED is aimed at each detector Changes in the scanner s position are monitored as changes in the position of each LED light spot on its detector One detector
202. mall around 10 or less As a result the changes in amplitude as the tip approaches the sample will also be small and the cantilever will be less sensitive Glitches which are very sharp may cause the system to select a less than optimum drive frequency Multiple peaks may be due to vibrational modes of the cantilever in its mounted configuration If the main resonance peak is not reasonably symmetric or is broad you should try switching to a different resonance peak If there is another resonance peak with high amplitude near the main peak move the cross hair just to the right side of that peak To move to a different resonance peak move the cursor which appears as a larger cross hair to the new peak and click the mouse button The new drive frequency should be displayed in the line below the plot If you cannot find another peak with sufficient amplitude then you should switch to a different cantilever Remove the cartridge from the probe head and insert a new chip carrier as you normally do Then repeat the system set up procedures starting from the step Aligning the Deflection Sensor 1 18 Chapter 1 NC AFM IC AFM and MFM Imaging 6 When you have located the optimal resonance peak to use check the location of the cross hair on the peak For NC AFM imaging you can use the selected drive frequency which lies on the right hand side of the peak The cross hair should not be located on a glitch or shoulder If
203. mation about the local elastic properties of the sample surface Chapter 5 I V Spectroscopy teaches you how to use the I V Spectroscopy window of ProScan Data Acquisition to generate current vs voltage I V and dI dV curves These curves are used to provide important information about surface electronic properties Chapter 6 Scanner Calibration describes how the scanner of your AutoProbe CP instrument works and how to calibrate it to maintain its optimal performance Part Ill Software Reference Part III of this User s Guide Software Reference is the reference manual for ProScan Data Acquisition and Image Processing and includes information for the following AutoProbe systems CP LS and M5 The chapters in this part of the User s Guide provide more detailed information about the software features and controls than the information that is provided in the tutorial chapters The chapters are designed so that you can skip straight to the feature or control that you are interested in learning more about Chapter 1 ProScan Data Acquisition describes in detail the software features of ProScan Data Acquisition This chapter discusses each region of the screen giving special attention to each control and its function This chapter also discusses the menus with a description of each menu item and its function Chapter 2 ProScan Image Processing describes in detail the software features of ProScan Image Processing Th
204. may need to realign the deflection sensor to perform an auto approach in contact AFM mode If you have a standard AutoProbe CP system and you have trouble realigning the deflection sensor open a Digital Voltmeter DVM by clicking the DVM icon Fi on the toolbar Click the button on the DVM window to see a selection of channels or signals and select A B The display of the DVM will show the value of the A B signal or probe signal given in volts or millivolts depending on the value If the DVM shows that the A B signal is not small then adjust the forward backward screw to move the PSPD until the absolute value of the A B signal is less than 300 mV The laser spot should now be centered on the PSPD 1 52 Chapter 1 NC AFM IC AFM and MFM Imaging 10 Take a contact AFM image of surface topography If alteration of the magnetic properties of the sample through contact with a magnetized tip is a concern you can switch to a non magnetized tip before taking the contact AFM image Switching tips however makes alignment of magnetic and topographic images more difficult Applying an Electrostatic Bias Between the Tip and the Sample For MFM imaging an electrostatic bias is sometimes applied between the tip and the sample when obtaining a stable image of magnetic or topographic features is difficult An electrostatic bias applied to the sample the tip is grounded creates charge on the sample surface which superimposes
205. mes corrupted The above listed general procedures for file management are broken into detailed steps below The directions assume you are using Windows 95 1 Create the c scancal directory a From the Start menu point to Programs and select Explorer Open the c drive b From the File menu click New then click Folder This creates a new folder in c The label of the folder icon will be highlighted to indicate that it can be altered c Type scancal in the new folder icon label and press the Enter key 2 Select the scanner calibration parameter file be copied Using Windows Explorer go to the folder c psi cal Identify the scanner calibration parameter file s you wish to copy For example you will most likely wish to copy the file for the scanner you most recently calibrated 3 With the cursor on that file click the right mouse button to open the right mouse button menu 4 Copy the scanner calibration parameter file from c psi cal to c scancal Select Copy from the right mouse button menu b Move the cursor to the c scancal folder Click the right mouse button again and click Paste from the right mouse button menu c A copy of the selected scanner calibration parameter file will appear in the c scancal folder Calibrating a 100 Micron Scanner 6 39 You have now created a backup copy of the scanner calibration parameter file 6 40 Chapter6 Scanner Calibration Summary This chapter desc
206. monitors and set up the system software Align the deflection sensor Set NCM parameters Under the Setup menu of the Image mode window select NCM Frequency to view the NCM Non Contact Mode Frequency Set dialog box Select a drive frequency drive amplitude drive and imaging amplitude set point for the scan Perform an auto approach In Move mode use the z direction pad to lower the tip so that it is close to the sample Click the button to initiate an auto approach The auto approach stops when the cantilever s vibration amplitude matches the value represented by the set point parameter displayed on the Image mode window Enter Image mode to view a Topography signal trace Reduce the absolute value of the set point parameter until you see magnetic features of the sample surface represented by the Topography signal trace Continue to reduce the set point absolute value until you see oscillations on the signal trace Increase the set point absolute value just enough to remove the oscillations Set scan parameters Set the scan rate scan size number of data points per image and fast scan direction Adjust the drive set point gain and slope parameters if necessary Start a scan Select additional signal channels for viewing if desired Click the button to begin acquiring an MFM image While imaging continue to monitor and adjust the scan parameters Taking anMFM Image 1 37 The sections tha
207. must take a new image To generate more than one I V curve do the following 1 Make sure that the I V option button is selected 2 Position the cursor at the new x y location on the image and click the mouse 3 If desired change the bias voltage range the sweep rate and the number of sweeps as described in the previous section Generating a Current vs Voltage Curve 4 Click the button to start generating a current vs voltage curve Up to sixteen current vs voltage curves can be generated at different x y locations in the image The Buffer scrollbox arrows allow you to scroll through the stored I V curves Adjusting the Horizontal and Vertical Scales of an I V Curve If you have followed the steps in the previous sections a current vs voltage curve should be displayed in the I V Spectroscopy window The horizontal and vertical scales of the curve can be adjusted using the H Horizontal and V Vertical option buttons along with the button You can expand or shrink the units per grid division and adjust the starting value of the horizontal and vertical axes Note The procedures described in this section also apply to dI dV curves 5 10 Chapter 5 l V Spectroscopy To adjust the horizontal scale Select the H Horizontal option button This selects the horizontal scale to be adjusted Adjust the starting value of the horizontal scale This value is displayed on the left side of the current vs voltage curve
208. n Alternatively double click the Data Acquisition icon in the desktop The program opens to Move mode 4 Turn off the probe head by either deselecting Head ON from the Mode menu or clicking the Head ON icon 5 Select Configure Parts from the Setup menu Alternatively click the Configure Parts icon Ee The ProScan Database Configuration dialog box will open Note The Configure Parts option is only enabled when the probe head is turned off When the probe head is turned back on the system is prompted to load files pertaining to the installed hardware and mode of 6 10 Chapter6 Scanner Calibration operation This procedure ensures that files are updated before an image is taken 6 Configure the system software for taking an AFM image by making the following selections Head Type Select the type of probe hkad AFMSTM AFMNCM or AFMLFM that you are using If you are using a multitask probe head select AFMLFM CP LS Scanner Select the file that has the scanner calibration values for the scanner you are using Head Mode AFM Beam Bounce Cantilever Select the file that corresponds to the cantilever you are using Electrochemistry ON OFF OFF Voltage mode HI After you finish entering these selections click to return to the Move mode window 7 If you have not already done so reset the Z stage as described in Chapter 2 Part I of this User s Guide This synchronizes the positi
209. n i e to confirm that the scanner has not been damaged from handling 2 Scanner tube calibration values vary somewhat depending on scan conditions e g xy scan size and z range of topography Therefore you should calibrate the scanner tube whenever these scan conditions change 3 The properties of scanner tubes change over time so you should calibrate the detector offsets periodically e g once a week Performing this calibration frequently is relatively straightforward since it is automated In general you should calibrate the scanner any time you think calibration could improve its performance Following are two sections The first includes background information and calibration procedures for instruments equipped with a5 um scanner Next is a section that includes background information and calibration procedures for instruments equipped with a 100 um scanner Read the section that applies for the scanner you are using Calibrating a5 Micron Scanner 6 5 Calibrating a 5 Micron Scanner This section includes background information and calibration procedures for a5 um scanner As mentioned in the introduction of this chapter standard AutoProbe CP instruments come with a 5 um scanner while AutoProbe CP multitask instruments come with a 100 um scanner Therefore this section applies if you have a standard AutoProbe CP or if you have purchased a 5 um scanner for a multitask AutoProbe CP This section is divided into t
210. n File to edit the values of first order scanner calibration parameters for low voltage mode First order calibration of the scanner sensitivity is now completed for high and low voltage modes You are ready to continue and perform the procedures for second order calibration of the scanner sensitivity Second Order Calibration of Scanner Sensitivity in X and Y In this section you will determine the values of second order calibration parameters Second order terms account for nonlinear behavior of the scanner for large scan sizes The addition of these terms improves the accuracy of scan sizes for large scans The procedure is similar to that for determining the first order parameters A larger scan size is used and the formula for calculating the correct parameter values is different Again the software keeps track of two sets of second order calibration parameter values one for high voltage mode and another for low voltage mode However since the maximum scan size in low voltage mode is between 1 and 1 5 um depending on the scanner determining second order scanner calibration parameter values for low voltage mode is not necessary The names and descriptions of the second order parameters are the following MicronPerDacSq_FastSX Calibrates additional scanner movement with voltage in x for large scans when x is the fast scan direction MicronPerDacSq_SlowSX Calibrates additional scanner movement with voltage in x for lar
211. n click the button to stop sweeping Note You may need to adjust the scanner s sweep range to cover the snap in and snap back points of the F vs d curve Figure 4 2 shows an example of an F vs d curve displayed on the graph of the Spectroscopy mode window The various parts of the curve in the figure that are labeled are described in the section Understanding Force vs Distance Curves later in this chapter Acquiring Force vs Distance Data 4 17 Note The extension and retraction paths of the curve are offset along the horizontal axis so that labels on the curve can be shown more clearly As mentioned earlier if you are plotting the Z Detector signal along the horizontal axis offset due to scanner hysteresis should be minimized Zero force ap out force attractive Snap in force attractive Scale Offset Zoom Buffer Auto lt gt He OMeasure 0 Run Acq Stop Reset Copy Load Save Extend Retract Cal Sweep Calibrate 1 36 1 187 um 2584 00 0 000 nN Print Setup aes Figure 4 2 A force vs distance curve generated using Spectroscopy mode You will notice a heavy horizontal line and a heavy vertical line on the graph These lines mark the horizontal and vertical axes of the F vs
212. n locate the main cantilever resonance peak An example is shown in Figure 1 3 Note If you have already generated a frequency response curve in a given working session with the instrument software then the frequency range covered when you click the button will match the range covered by the most recent sweep If this range is not large enough to include the main resonance peak of your cantilever click the button to sweep over a larger frequency range NCM Frequency Set X D 100mum div Set 0 184 Drive crossthair wes OkHz f 96380 Hz 100KHz div Zoom In Zoom Out Refresh Done Help Figure 1 3 A frequency response curve for a typical NC AFM cantilever 1 16 Chapter 1 NC AFM IC AFM and MFM Imaging The number of kHz per division for the horizontal axis is displayed at the right side of the line below the plot The starting frequency is labeled below the lower left corner of the plot The units per division for the vertical axis represent cantilever oscillation amplitude given in arbitrary units eArbs or units of distance if the Error signal sensitivity has been calibrated They are displayed at the left side of the line above the plot Note You may change the units of the vertical axis by selecting Servo Unit from the Setup menu and then selecting a new unit from the Servo Set Point drop down list
213. nal on axis microscope with color video monitor for probe tip and sample view 5 1 zoom up to 3 500X magnification Optional acoustic isolation chamber XX Preface Workstation AEM Computer Mass storage Software Graphics System power Dimensions and Weights CP base unit AEM Computer Operating Environment Temperature Humidity Cleaning Agents CP base unit Probe head AEM and computer 20 bit DACs for x y and z axes 16 bit DACs for system control 100 MHz Pentium processor 256 Kbyte cache memory 16 MB RAM 1 GB hard drive 3 1 2 in 1 4 MB floppy disk drive ProScan Data Acquisition and Image Processing operates under Windows 95 Windows graphics accelerator 17 in high resolution color monitor 115 230 V AC 50 60 Hz 600 W 10 5 in 267 mm x 8 in 203 mm 22 lb 10 kg 17 in 432 mm x 7 1 2 in 191 mm x 17 1 2 in 445 mm 43 Ib 20 kg 17 in 432 mm x 7 1 2 in 191 mm x 17 1 2 in 445 mm 27 Ib 12 kg 0 C to 30 C 32 F to 112 F 90 noncondensing Isopropyl alcohol Isopropyl alcohol Isopropyl alcohol WARNING To avoid risk of electric shock do not clean AutoProbe CP system components when power to the components is turned on CAUTION Do not use acetone to clean AutoProbe CP system components Acetone may damage important safety warning labels xxi ThermoMicroscopes Warranty Statement Warranty on New Systems and Accessor
214. nal with distance The procedure is similar to that for calibrating the xy detector except that you need to use a sample with a z step height of a known distance a step height standard in place of the 9 9 um grid sample Since the detectors are not affected by the range of volts to the scanner this calibration procedure only needs to be performed in high voltage mode Calibrating a 100 Micron Scanner 6 35 1 Install a step height standard in place of the 9 9 um grid sample 2 Select Input Configuration from the Setup menu and add the Z Detector signal to the list of Selected signals in the box on the right side of the dialog box Click to close the dialog box 3 From the Image mode window select the Z Detector signal from the drop down list below the Oscilloscope Display 4 Approach the sample set scan parameters and take a contact AFM image as you normally do Be sure that the step of known height on your sample is included in the image In addition scan across the step in the fast scan direction 5 Once the image is complete use the Line Analysis software tools described in the Image Processing chapter of Part III of this User s Guide to measure a known distance in the z direction on the image generated from the Z Detector signal 6 Compare the measured distance value to the known distance value Ifthe distance produced by the software measurement tools is incorrect then the z detector calibration value
215. nd sample biases are set using scrollboxes in the Image mode window Preparing and Loading STM Tips 2 3 Preparing and Loading STM Tips You can prepare an STM tip using several different methods This section describes two methods commonly used for preparing STM tips 1 by cutting a wire and 2 by using a tip etcher A new STM tip must be prepared when the STM is first set up and also whenever the tip being used becomes damaged or oxidized If you are taking STM images of a surface with high aspect ratio features sharp or steep you should make etched tips Etched tips have a much higher aspect ratio than tips made using wire cutters If you try to image a surface with tall or steep features using a relatively blunt cut wire tip a tunneling current may occur between the side of the tip and the side of a surface feature If this happens you will see tip imaging effects in the STM image If you are taking STM images of an atomically flat surface for instance the surface of graphite blunt cut wire tips may be more stable over time than etched tips and result in better STM images However multiple tip imaging effects can also occur when blunt tips are used Using Wire Cutters to Make STM Tips You can make reasonably good tips by cutting tungsten or PtIr wire at a 45 angle with a pair of sharp wire cutters The recommended wire diameter to use is 0 020 20 mil wire or 0 5 mm wire This wire diameter can also be used with the
216. nd order scanner calibration parameters Next you will enter the corrected MicronPerDac_SZ parameter value into the scanner calibration parameter file Editing the Scanner Calibration File 1 From the Move mode window use the z direction pad to withdraw the tip from the sample 2 Turn off the probe head by either deselecting Head ON from the Mode menu or clicking the Head ON icon TE 3 Select Calibration Edit from the Setup menu Click in the Warning box to indicate that you want to proceed 4 Select the Scanner category in the left listbox 5 Select MicronPerDac_SZ from the list of calibration parameter values 6 Change the value of the parameter by typing the new value into the textbox above the Calibration Values listbox Press the Enter key after entering the new value so that the correction is recognized by the software 7 Click to register the change and close the dialog box The scanner sensitivity is now calibrated in the z direction for high voltage mode After the correction is made the software should measure the step height correctly 6 22 Chapter 6 Scanner Calibration Z Calibration in Low Voltage Mode If you plan to operate frequently in low voltage mode you should repeat the procedures to calibrate the scanner sensitivity in z for low voltage mode 1 Switch to low voltage mode by selecting Low Voltage from the Mode menu 2 Follow Steps 3 through 6 of the earlier section Ta
217. ner fully in its attempt to match the set point value then you need to re approach the sample Re approaching allows the system to use the motorized Z stage to decrease the tip to sample spacing 5 Continue to incrementally decrease the set point value while watching both the Topography signal trace and the Z Piezo bar Decrease the value until you see that the sample topography is represented by the signal trace and the scanner is operating roughly in the middle of its z range of motion Re approach if necessary to position the scanner optimally in the middle of its z range of motion Each click of the mouse button on the Set Point scrollbox arrow changes the third decimal place of the number shown You should find that there is a threshold set point value above which you see no sample topography represented by the signal trace and below which topography is represented Stop decreasing the set point once you reach the threshold set point value Note The threshold set point value is roughly the same for the same sample and tip So if you take another image at a later time you may want to start with an absolute set point value just slightly greater than the previously determined threshold set point value to save time In the next section you will adjust other scan parameters such as the gain As you adjust these parameters you may also want to adjust the set point value again to optimize the signal trace If you have troubl
218. ng sample topography with little or no contact between the tip and the sample The total force between the tip and the sample in the non contact regime is very low generally about 10 N This low force is advantageous for studying soft or elastic samples Because the force between the tip and the sample in the non contact regime is low however it is more difficult to measure than the force in the contact regime which can be several orders of magnitude greater In addition cantilevers used for NC AFM must be stiffer than those used for contact AFM because soft cantilevers can be pulled into contact with the sample surface The small force values in the non contact regime and the greater stiffness of the cantilevers used for NC AFM are both factors that make the NC AFM signal small and therefore difficult to measure Thus a sensitive AC detection scheme is used for NC AFM operation In non contact mode the system vibrates a stiff cantilever near its resonant frequency typically from 100 to 400 KHz with an amplitude of a few tens to hundreds of angstroms Then it detects changes in the resonant frequency or vibration amplitude as the tip comes near the sample surface The sensitivity of this detection scheme provides sub angstrom vertical resolution in the image as with contact AFM The relationship between the resonant frequency of the cantilever and variations in sample topography can be explained as follows The resonant frequency of a c
219. nse DA Vv lt forscan taken left to right gt Cantilever response forscan taken right to left lt c AFM line trace gt LFM line trace forscan d taken leftto right gt LFM line trace forscan taken right to left Figure 3 3 Cantilever response to change in frictional coefficient and topography and corresponding AFM and LFM signal traces Figure 3 3a shows a change in frictional coefficient that causes the cantilever to bend to the right for a scan that is taken from left to right If the scan is taken from right to left as illustrated in Figure 3 3b the cantilever bends to the left as it passes over the change in frictional coefficient A change in topography causes the same type of cantilever bending as was illustrated in Figure 3 2 Figure 3 3c shows an AFM signal trace resulting from the surface of Figure 3 3a the data only reflect the change in sample topography Figure 3 3d shows the LFM signal trace that would result from a scan taken from left to right Figure 3 3e shows the LFM signal trace that would result from a scan taken from right to left The sign of the LFM signal flips for the change in friction but not for the change in topography Changes in topography appear on an LFM image as adjacent dark bright regions By identifying these adjacent dark bright regions and by viewing data from two scan directions a user looking at an LFM image can distinguish between contrast change
220. nsepsnee 5 3 YV Spectroscopy COntTols seser lest Renee 5 5 Acquiring Current vs Voltage Data 5 7 Generating a Current vs Voltage Curve nenn 5 7 Generating an I V Curve at a Different X Y Location s een 5 9 Adjusting the Horizontal and Vertical Scales of an I V Curve 5 9 Zooming in on a Region of Interest 5 11 Zooming in Graphically Using the Cursor 0 0 eee sus 5 11 Zooming in by Changing the Voltage Sweep Range 5 11 Making Point to Point Measurements on an I V Curve s es 5 12 Saving and Exporting Data 5 12 Redisplaying Curves in I V Spectroscopy uesseessessnesnnesnnesnnennensnensnenne ernennen 5 13 SUMMALY 5 seien Maire baste ied weasel ian meee E N 5 14 Introduction riesen peek Ebi eer hao ee tee eevee 6 2 How the Scanner Works sise 6 3 When to Calibrate the Scanner ss 6 4 Calibrating a 5 Micron Scanner ss 6 5 What it Means to Calibrate a 5 Micron Scanner 6 5 Scanner Calibration Procedures ss 6 6 Setting Up the System 6 7 First Order Calibration of Scanner Sensitivity in X and Y 6 11 Second Order Calibration of Scanner Sensitivity in X and Y 6 17 Calibration of Scanner Sensitivity in Z 6 20 Creating a Backup Scanner Calibration File 6 23 Calibrating a 100 Micron Scanner ss 6 24 How
221. nten zeigt den Ort der Laserwarnungsmarkierungen auf dem usseren AutoProbe CP Geh use an CAUTION LASER LIGHT WHEN OPEN DO NOT STARE INTO BEAM Bild 0 6 Laserwarnungsort des AutoProbe CP Geh uses Bild 0 7 unten zeigt den Ort der Lasersicherheits bereinstimmungskennzeichnung auf der R ckseite des AutoProbe Elektronic Modules AEM an AEM H 00000 Betriebssicherheit xxxv 1171 Borregas Ave Sunnyvale CA 94089 1304 Date Serial No Patents 5 157 251 5 210 410 5 376 790 5 448 399 100 120 220 240 VAC 50 60 Hz 400W Complies with 21 CRR 1040 10 and1040 11 Made in the USA IMTHERMOMICROSCOPES AutoProbe Electronics Module Model No APEM 1000 CE Bild 0 7 Riickseite des AEM den Ort der Lasersicherheitsiibereinstimmungskennzeichnung anzeigend xxxvi Vorwort und bersicht Spezifikationen und Ausf hrungen des AutoProbe CP s System Ausf hrungen Standard Beinhaltet einen AFM Tastkopf f r T tigkeit in der AFM Betriebsart Ein AFM NC AFM Tastkopf f r T tigkeit in AFM ber hrungsfreies AFM periodisch kontaktierendes AFM und MFM Betriebsarten ist zus tzlich erh ltlich Ein AFM LFM Tastkopf f r T tigkeit in AFM und LFM Betriebsarten ist zus tzlich erh ltlich Ein STM Werkzeugset f r T tigkeit in STM Betriebsart ist zus tzlich erh ltlich Multitask
222. nto the support arms of the XY Translation Stage as described in Chapter 2 Part I of this User s Guide Make sure that the LASER ON OFF switch is in the OFF position before you install the probe head Setting upthe System 3 9 If you have the standard AutoProbe CP system configuration Install the AFM LFM probe head A connector on the rear of the probe head plugs into a connector on the back of the translation stage Figure 3 4 shows the AFM LFM probe head used with the standard system configuration If you have the multitask AutoProbe CP system configuration Install the multitask probe head and set the two mode switches on the probe head to the AFM and LFM positions Once the probe head is installed turn the LASER ON OFF switch to the ON position laser position laser indicator power on off switch laser beam gt J steering screws Reade chip carrier PSPD adjustment screws stub sample cartridge underside Figure 3 4 The AFM LFM head Load a cantilever chip Place an AFM chip carrier in the probe cartridge Place the cartridge in the probe head Make sure that you push the cartridge in so that the balls on the cartridge click into place in the probe head 3 10 Chapter 3 LFM Imaging Configuring the Software 1 Turn on all of your system components as you normally do Refer to Part I of this User s Guide for details 2 Open ProScan Data Acquisiti
223. ntrols of the Spectroscopy window If you want to start the tutorial you can skip these sections and return to them at a later time The Force vs Distance Graph The upper portion of the Spectroscopy window shows a graph where a force vs distance curve is displayed The horizontal axis of this graph represents distance or z position of the scanner The vertical axis of the graph represents the force exerted on the cantilever The default signal plotted on the horizontal axis is the Z Drive signal which is the volts sent to the scanner to set its z position The Z Detector signal can also be plotted on the horizontal axis and is represented as nm on the graph The starting value and the number of units per division for the horizontal axis are displayed at the left and right sides of the graph respectively The signal plotted on the vertical axis represents vertical deflection of the cantilever You can calibrate the vertical axis with units of force by following the instructions of the section Calibrating the Vertical Axis with Force later in this chapter The starting value and the number of units per division for the vertical axis are displayed at the bottom and top of the graph respectively The F vs dSpectroscopy Window 4 5 Spectroscopy Mode Controls This section describes the controls in the F vs d Spectroscopy window see Figure 4 1 Table 4 1 below lists each control in the window along with a brief description of
224. o display V laser beam steering screws green up down O PSPD E forward 7 backward CAUTION LASER LIGHT DO NOT STARE INTO BEAM 0 2 mW AT 600 700 nm CLASS II LASER PRODUCT AVOID EXPOSURE LASER LIGHT IS EMITTED FROM THIS APERTURE PER EN60825 1 1994 Figure 0 3 Emplacement des contr les laser sur la t te du microscope Les contr les et indicateurs montr s ci dessus en figure 0 3 ont les fonctions suivantes L interrupteur on off du laser active ou d sactive le laser dans la t te du microscope Une lumi re rouge est allum e dans l interrupteur lorsque le laser est enclench Vis directrices du rayon laser Les deux vis directrices du rayon laser situ es sur le dessus droite de la t te du microscope sont utilis es pour ajuster la position du rayon laser touchant le cantilever Les vis bougent le spot du laser dans deux directions comme montr sur la Figure 0 1 ci dessus Si votre syst me inclus l option CP optique vous pouvez contr ler ces ajustements en utilisant la vue optique sur votre moniteur vid o Vis d ajustement PSPD Il y a deux vis PSPD sur la t te du microscope haut bas et avant arri re Ces vis ajustent la position du PSPD dans la t te du microscope pour centrer la lumi re du laser reflet e sur le photodetecteur La vis d ajustement avant arri re est utile pour l alignement PSPD sur la t te du mi
225. o point measurements on an I V or dI dV curve Buffer Allows you to scroll through current vs voltage and dI dV curves Cop Allows you to place numerical values of current as a function of voltage from the I V Spectroscopy window to the Clipboard From there data can be pasted into any appropriate Windows application for analysis Saves I V curves i e numerical information corresponding to each I V curve and dI dV curves to the image file Allows you to redisplay I V and dI dV curves previously saved to an image file Acquiring Current vs Voltage Data 5 7 Acquiring Current vs Voltage Data This section explains in detail how to use the controls of the I V Spectroscopy window The basic steps for current vs voltage data acquisition are the following 1 10 Take an STM image as you normally do and then import the image into the Import View Open the Spectroscopy window by either selecting Spectroscopy from the Mode menu or clicking the Spectroscopy icon Es on the Toolbar Click the button in Image mode to stop the rastering of the probe Select the I V option button to select a current vs voltage curve to be generated Select the location on the image where you want to generate the current vs voltage curve In the From and To textboxes set the range of the bias voltage that will be applied to the sample during current vs voltage data acquisition In the Rate scrollbox enter the rate at
226. of the probe head plugs into a connector on the back of the translation stage If you have the multitask AutoProbe CP system configuration Install the multitask probe head and set the two mode switches on the probe head to the STM and LFM positions 2 14 Chapter 2 STM Imaging Once the probe head is installed turn the LASER ON OFF switch to the ON position Turn on all of your system components as you normally do Refer to Part I of this User s Guide for details Load a gold calibration grating sample onto the scanner Note STM samples must be mounted so that they are in electrical contact with the sample holder otherwise no tunneling current can flow between the tip and the sample Do not use double sided tape to secure a sample to a sample mounting disk Instead secure samples using a conductive paint or glue such as silver epoxy or silver paint Install the STM cartridge in the probe head Hold the STM cartridge with the sharp tip pointing down Insert the STM cartridge into the probe head by sliding it into the two grooves as you usually do for AFM Wiggle the cartridge in and out a bit to make sure that all three balls on the cartridge are engaged Note If you are using a calibration grating as a sample for instance a 1 um gold grating it is best to use an etched STM tip Etched tips have a higher aspect ratio which is better for scanning samples with high aspect ratio features Configuring the Software
227. of the standard system configuration For the multitask configuration when the brightness of the center green light which has variable brightness is maximized the laser intensity hitting the PSPD is maximized See Figure 0 5 below Multitask probe heads sc analog for variable brightness Figure 0 5 Laser intensity and position indicators for the multitask probe head xviii Preface Laser position indicators Indicate the position of the reflected laser light hitting the PSPD When the laser spot is centered on the photodetector the center green light is lit as shown in Figures 0 4 and 0 5 above Figure 0 6 below shows the location of the laser warning labels on the outer housing of AutoProbe CP CAUTION LASER LIGHT WHEN OPEN DO NOT STARE INTO BEAM Figure 0 6 Laser warning location on AutoProbe CP housing Figure 0 7 below shows the location of the laser safety compliance label on the rear panel of the AutoProbe electronics module AEM AEM PM THERMOMICROSCOPES 1171 Borregas Ave Sunnyvale CA 94089 1304 AutoProbe Electronics Module Model No APEM 1000 Date Serial No Patents 5 157 251 5 210 410 5 376 790 5 448 399 100 120 220 240 VAC 50 60 Hz 400W Complies with 21 CRR 1040 10 and1040 11 Ce Made in the USA Figure 0 7 Rear panel of the AEM
228. olierung des Ger tes ZN Weisst den Benutzer auf eine in der Dokumentation enthaltene Information hin A Zeigt eine Ber hrungsgefahr an Definitionen Warnung Vorsicht und Beachte Im Benutzerhandbuch werden drei verschiedene Bezeichnungen Warnung Vorsicht und Beachte benutzt um auf die Betriebssicherheit des AutoProbe CP hinzuweisen Diese Bezeichnungen sind in Tabelle 0 2 definiert Tabelle 0 2 Sicherheits Bezeichnungen und ihre Definition Bezeichnung Definition Warnung Warnt vor m glicher ernsthafter Verletzungsgefahr falls dem im Benutzerhandbuch beschriebenen Arbeitsablauf nicht unbedingt Folge geleistet wird Der Arbeitsablauf darf nicht fortgefiihrt werden bis nicht alle Voraussetzungen verstanden und erf llt sind Vorsicht Macht auf m gliche Sch digung des Systems oder Verschlechterung der Sicherheit aufmerksam falls dem im Benutzerhandbuch beschriebenen Arbeitsablauf nicht unbedingt Folge geleistet wird Beachte Macht auf eine zu beachtende Benutzungsregel oder ungew hnliche Voraussetzung aufmerksam Es ist wichtig dass alle Warnungen Vorsichts und Beachte in diesem Handbuch achtsam gelesen werden um die Bedienungssicherheit ihres AutoProbe CP Systems zu gew hrleisten Betriebssicherheit xxvii Zusammenfassung der Warnungen und Vorsichts Dieser Abschnitt beinhaltet die Warnungen und Vorsichts die unbedingt befolgt werden m ssen wann immer das AutoProbe CP betrieben wird WARNUN
229. oll through the buffers to the F vs d curve that you want to print 6 Click the button The F vs d curve will be printed along with its associated image and the x y location of the curve on the image Acquiring Force vs Distance Data 4 25 Redisplaying Curves in F vs d Spectroscopy F vs d curves that were saved to an image file can be redisplayed during a later Spectroscopy mode working session To redisplay previously saved curves do the following 1 If the F vs d Spectroscopy window is not open open it now by either selecting Spectroscopy from the Mode menu or clicking the Spectroscopy icon on the Toolbar 2 Open the Load to Buffer dialog box by selecting Load from the File menu 3 In the Load to Buffer dialog box select the file name of the image you want to load to the Image Gallery and then click the button to close the dialog box The selected image should appear in the Image Gallery 4 Select the image in the Image Gallery a green box will enclose the selected image and then click the button to import the image into the Import View Note Sometimes an image displayed in the Import View appears very small in the center of the display Click the button of the Import View to expand the image in the display 5 Click the button in the F vs d Spectroscopy window The F vs d curve in the first of the sixteen buffers associated with the selected image appears on the graph of the Spectr
230. omes flat during imaging this may be due to amplifier saturation 1 34 Chapter 1 NC AFM IC AFM and MFM Imaging 2 If you see that the signal trace shows saturation do the following Lift the tip _ Generate a new frequency response curve in the NCM dialog box and re select the drive frequency Reduce the drive parameter and or the set point parameter The best results in IC AFM mode are normally obtained after some practice On very soft or sticky samples one usually has to acquire some experience with IC AFM and the specific sample before obtaining the best possible images If the sample does not image well after some experimentation then NC AFM may be required Taking anMFM Image 1 35 Taking an MFM Image This section leads you step by step through the process of taking an MFM image of the hard disk sample included in your MFM toolkit It assumes that you have read through the section Taking an NC AFM Image and are familiar with the procedures described there This section refers to Taking an NC AFM Image where applicable The procedures for taking an MFM image are very similar to those for taking an NC AFM image For MFM imaging however you adjust the set point parameter so that the tip to sample spacing is larger than that for NC AFM imaging In this distance regime the gradient of the magnetic force is dominant over the gradient of the van der Waals force Refer to the section How Magneti
231. on From Start point to the Program folder and select ThermoMicroscopes ProScan Then click the Data Acquisition icon Alternatively double click the Data Acquisition icon in the desktop The program opens to Move mode 3 Turn off the probe head by either deselecting Head ON from the Mode menu or clicking the Head ON icon 4 Open the ProScan database configuration dialog box by selecting Configure Parts from the Setup menu Alternatively click the Configure Parts icon Ba 5 Configure the system software for LFM mode To do this make the following selections Head Type AFMLFM Scanner Select the file that has the scanner calibration values for the scanner that you are using Head Mode AFM Beam Bounce Cantilever Select the name of the file that corresponds to the cantilever you are using Electrochemistry ON OFF OFF For Voltage Mode HI After you have finished making these selections click the button which sets the chosen system configuration items and returns you to Move mode 6 If you have not already done so reset the Z stage as described in Chapter 2 Part I of this User s Guide This synchronizes the position of the Z stage with the coordinate system of the software Aligning the Deflection Sensor The following steps describe how to align the deflection sensor for an AFM LFM head These steps apply only if you are using the standard system configuration of AutoP
232. on p Y 2 Start with the default value of the drive parameter which is 25 Generate a frequency response curve in the NCM Frequency Set dialog box as described in the section Selecting a Drive Amplitude for NC AFM imaging If the frequency response curve saturates on the graph of the NCM dialog box then you need to decrease the drive amplitude Vary the value until the maximum peak height of the response curve is roughly half of the full vertical scale on the zoomed out sweep 3 To change the drive amplitude enter a percentage in the Drive scrollbox of the NCM dialog box 4 Press the Enter key so that the software recognizes the change and click the button to see the change in the response curve You can also adjust the drive amplitude during a scan from within Image mode by changing the drive parameter Selecting a Drive Frequency The drive frequency is the frequency of the AC signal from the sine wave generator that drives the cantilever vibration For IC AFM imaging the drive frequency should be slightly less than or on the left side of the frequency of the cantilever s main resonance peak For drive frequencies on the left hand side of the resonance peak the cantilever vibration amplitude increases as the tip is brought closer to the sample For a detailed discussion of the relationship between the drive frequency and the vibration amplitude refer to the section How Intermittent Contact AFM
233. on of the Z stage with the coordinate system of the software 8 Make sure that the power to the probe head is on If the power to the probe head is turned off turn it on by clicking the Head ON icon If the LASER ON OFF switch is in the OFF position turn it to the ON position Note If you are using a multitask probe head set the AFM STM switch to the AFM position and the LFM NC AFM switch to the LFM position 9 Align the deflection sensor as described in Chapter 2 Part I of this User s Guide You are ready to begin calibrating the scanner sensitivity First Order Calibration of Scanner Sensitivity in X and Y The calibration parameters you will determine in this section are termed first order calibration parameters because they are used to describe the linear behavior of the scanner position with applied voltage appropriate for small scan sizes There are four first order calibration parameters listed below MicronPerDac_FastSX Calibrates scanner movement with voltage in x for small scans when x is the fast scan direction Calibrating a5 Micron Scanner 6 11 MicronPerDac_SlowSX Calibrates scanner movement with voltage in x for small scans when x is the slow scan direction MicronPerDac_FastSY Calibrates scanner movement with voltage in y for small scans when y is the fast scan direction MicronPerDac_SlowSY Calibrates scanner movement with voltage in y for small scans when y is the slow sc
234. on sa d cision les pi ces renvoy es ThermoMicroscopes Le client doit demander l avance une autorisation d exp dition de mat riel ThermoMicroscopes RMA et suivre la proc dure ThermoMicroscopes d exp dition Exception faite aux conditions de garantie pr cit es le vendeur ne fourni aucune garantie de fa on formelle ou implicite et exclu d savoue express ment toutes formes de garantie se rapportant la marchandabilit ou l adaptation un usage particulier ThermoMicroscopes ne pourra en aucun cas tre design comme responsable des pertes ou dommages indirects directs ou cons cutifs survenus lors d une utilisation ou d une immobilisation de produits services pi ces fournitures ou quipement ThermoMicroscopes sera galement d gag de toutes responsabilit s vis vis de la loi x Preface and Overview incluant mais sans s y limiter aux pertes de profits retards mauvaise volonte dommage et toutes sortes de co ts de r cup ration reprogrammation ou reproduction des programmes ou informations contenues ou utilis es avec les produits ThermoMicroscopes Certains tats n admettent pas de limitation dans le temps de garanties implicites et ou l exclusion ou la limitation d incidents ou de dommages sp ciaux Dans ce cas les limitations et ou exclusions pr cit es ne vous concernent pas Ces garanties vous donnent des droits sp ciaux et vous pouvez galement tre soumis d
235. ons in the Extend and Retract micron textboxes The maximum range corresponds to the z throw of the scanner you are using The zero point of the scanner s sweep range is defined as the software s estimate of the sample surface marked by the black half of the Set Point arrow You can change the limits of the scanner s sweep range by typing new values into the Extend and Retract micron textboxes which is equivalent to dragging the right and left ends of the red Piezo Adjustment bar respectively Now that you are familiar with the controls of the Spectroscopy window you are ready to set up to acquire an F vs d curve Acquiring Force vs Distance Data 4 9 Acquiring Force vs Distance Data This section explains in detail how to use the controls of the F vs d Spectroscopy window The basic steps for generating a force vs distance curve are the following Set up the system for contact AFM data acquisition and perform an auto approach Take an image of your sample and then import the image into the Import View From the Mode menu select Spectroscopy Stop the rastering of the scanner by clicking the button Select a point on the image where you would like to generate an F vs d curve Click the button to generate an F vs d curve Adjust parameters Click the button to acquire a curve that can be saved Click the button to save acquired curves to the image file RAN A ID ce These steps are described in detail in the se
236. or lower the z position of the piezoelectric scanner in order to maintain a constant amplitude of cantilever vibration Since changes in the amplitude are due to changes in the force gradient between the tip and the sample the feedback loop keeps the force gradient constant during a scan The sample is mounted on the scanner and it moves relative to the probe When the z position of the scanner is raised the tip and sample are brought closer together and the force gradient between the tip and sample increases When the scanner is lowered the tip and sample move further apart and the force gradient decreases By adjusting the tip to sample spacing the system controls the force gradient during a scan keeps it constant The z voltage applied to the scanner to maintain a constant force gradient is used to generate an image of surface topography z voltage vs scanner position 1 68 Chapter 1 NC AFM IC AFM and MFM Imaging Summary This chapter presented procedures for taking NC AFM IC AFM and MFM images For each imaging mode you learned how to set up the system hardware and software select scan parameters such as the drive frequency the drive amplitude and the imaging amplitude and take an image Also included was background information on how NC AFM IC AFM and MFM work Understanding how these methods work helps you to take the highest quality images for the widest range of samples Chapter 2 STM Imaging 2 2 Chapter2 ST
237. oscopes bernimmt die Verantwortung das Ger t welches unter diese begrenzte Garantie f llt nach eigenem Ermessen zu reparieren oder zu ersetzen ohne Kosten f r den K ufer Alle Serviceleistungen werden je nach ermessen von ThermoMicroscopes in ThermoMicroscopes Niederlassungen oder beim Kunden durchgef hrt Bei Reparaturen welche in ThermoMicroscopes Niederlassungen durchgef hrt werden muss ThermoMicroscopes vorzeitig kontaktiert werden um eine Genehmigung f r die R cksendung des Gr tes zu erhalten F r den Transport des Ger tes muss den ThermoMicroscopes Transportanleitungen unbedingt Folge geleistet werden Falls das Ger t zur ckgesendet wird muss es versichert werden Wenn immer m glich liefert ThermoMicroscopes Ersatzteile als Leihgabe um eine Reparatur beim Kunden mit m glichst geringer Stillstandzeit zu erm glichen Wenn das System wieder betriebsbereit ist m ssen die defekten Teile umgehend zu ThermoMicroscopes zur ck gesandt werden Speziell ausgeschlossen von dieser Garantie sind alle Verbrauchsartikel wie Piezolevers Microlevers Ultralevers Spitzen und hnliches F r Ger te die ausserhalb der Vereinigten Staaten verkauft wurden gelten die Garantiebedingungen des individuellen Verkaufes Ger te welche Gegenstand von falscher Benutzung Unfall Missbrauch Missgeschick unzumutbarer Benutzung Besch digung durch Drittger te mit welchen das Ger t benutzt wurde Bedienungsfehler Vernachl ssigung une
238. oscopy window 6 Use the Buffer scrollbox arrows to scroll through the stored curves The x y location on the image where each curve was taken is marked on the image in the Import View 4 26 Chapter 4 Force vs Distance Where to Go From Here This concludes the tutorial portion of this chapter At this point you can review the tutorial and practice taking F vs d curves until you feel confident with the techniques described here If you are interested you may want to continue and read the next sections which discuss underlying principles of F vs d data acquisition Forces Acting on the Cantilever 4 27 Forces Acting on the Cantilever Vertical deflection of the cantilever originates from several sources Attractive van der Waals forces between the tip and the sample pull the cantilever toward the surface Capillary forces exerted on the tip by liquid layers on the sample surface also pull the cantilever toward the surface In addition repulsive van der Waals forces essentially due to electrostatic repulsion between the tip and the sample deflect the cantilever away from the surface F F total net force on cantilever F F F F vertical van der Waals force x repulsive is shown Fe F capillary force Figure 4 3 Forces acting on the cantilever tip positive net force negative net force Figure 4 4 The effects of positive and negative net forces on cantilever bending Figure 4 3 shows the forces acting on t
239. ot covered by this warranty Warranty on Replacement Parts ThermoMicroscopes warrants all replacement parts to be sold free from defects in materials or workmanship for a period of 90 days from the date received by the customer ThermoMicroscopes will repair or replace at its discretion such parts when returned to ThermoMicroscopes Customers must contact ThermoMicroscopes in advance to obtain authorization to return parts and follow ThermoMicroscopes s shipping instructions Except as herein provided seller makes no warranties express or implied and seller expressly excludes and disclaims any warranty of merchantability or fitness for a particular purpose Under no circumstances shall ThermoMicroscopes be liable for any loss or damage direct special indirect or consequential arising from the use or loss of use of any product service part supplies or equipment Nor shall ThermoMicroscopes be liable under any legal theory including but not limited to lost profits down time goodwill damage to or replacement of equipment or property and any cost of recovering reprogramming or reproducing any program or data stored in or used with ThermoMicroscopes products xxii Preface Some states do not allow limitations on the period of time an implied warranty lasts and or the exclusion or limitation of special incidental or consequential damages so the above limitations and or exclusions may not apply to you This warranty gives you
240. ot to touch the etched end of the tip or you will damage the tip Ve Rinse the etched tip in deionized water and then in isopropyl alcohol Etched tungsten tips will oxidize and should not be kept longer than 1 to 2 days 2 7 2 8 Chapter2 STM Imaging Using the STM Cartridge For STM images you use a cartridge specifically designed for STM The STM cartridge contains a small hole for inserting an STM tip Figures 2 4 and 2 5 below show a side view of the STM cartridge and a view looking down on the cartridge respectively IE 0 020 tungsten tip inserted into cartridge STM p m for tightening tip Figure 2 4 Side view of STM cartridge with tip inserted On the top side of the cartridge you will see a round metal contact pad for delivering the tunneling current signal to the control electronics CAUTION Try to keep the area around the metal contact pad clean Preparing and Loading STM Tips metal contact pad Ia set screw 1 STM tip A a N t gr Figure 2 5 Top view of STM cartridge with STM tip inserted The tip is tilted relative to the sample instead of pointing straight down The tilt allows you to see the tip using the on axis optical view The STM cartridge is installed in the probe head in the same way as the AFM cartridge with the tip pointing down The instructions below explain h
241. ou with scan parameter values to use for taking an STM image of a graphite sample Taking an STM Image 2 13 Setting Up the System Setting up the system for STM operation involves setting up the hardware configuring the software and performing some simple diagnostic checks of the system For the best STM images your AutoProbe CP instrument should be placed on an air table for optimal vibration isolation Note In addition to the components included with your instrument you will need a digital multimeter for performing the diagnostic checks Setting Up Hardware This section includes steps for setting up the system hardware for taking an STM image 1 Install a scanner as described in Chapter 2 Part I of this User s Guide CAUTION The power to the AEM must be turned OFF before you remove or install the scanner CAUTION The four screws that connect the scanner to the CP base unit must be securely fastened to ensure proper grounding When the four screws are securely fastened maximum instrument performance is ensured since vibrations are reduced 2 Install the appropriate probe head by sliding it onto the support arms of the XY Translation Stage as described in Chapter 2 Part I of this User s Guide Make sure that the LASER ON OFF switch is in the OFF position before you install the probe head If you have the standard AutoProbe CP system configuration Install the AFM STM probe head A connector on the rear
242. ould be listed in the Selected listbox by default Click on MFM Phase from the list of signals in the Available listbox then click the button to add the MFM Phase signal to the list of signals in the Selected listbox 6 Click the button to return to Image mode Both the Topography and the MFM Phase signals should be available now in the drop down list below the Oscilloscope Display You may find it useful to view an image taken using the MFM Phase signal while you are taking either a Topography signal image or an MFM Amplitude image In either case select the MFM Phase signal in addition to the Topography or MFM Amplitude signal 7 Set scan parameters to values appropriate for either a Topography image or an MFM Amplitude image Note The sensitivity of the phase signal to changes in the force gradient is most pronounced at the resonant frequency of the cantilever For this reason you may want to open the NCM Frequency Set dialogue box and select a drive frequency that is very close to the maximum of the resonance peak Selecting a drive frequency value that is close to the cantilever s resonant frequency may improve the sharpness of MFM Phase images As mentioned in the earlier section Performing an Auto Approach you must always lift the tip before re selecting the drive frequency if an auto approach has been performed To make side by side comparisons of images taken with the different signal channels open two or more Ac
243. ovides a leakage path for current flow and the voltage reading may decrease with time The measured voltage should match the bias difference set in Image mode If there is an offset between the measured bias and the bias set using the system software you can account for this offset by adjusting the value of a calibration parameter in the Manual Calibration Entry Dialog box as follows 10 11 Click the Head ON icon to turn the power to the probe head off Select Calibration Edit from the Setup menu to open the Manual Calibration Entry dialog box Click the button of the Warning box to indicate that you wish to proceed Select Bias Voltage from the Category listbox Then select the TipBiasVoltsOffset parameter from the Calibration Values box so that its value appears in the textbox in the upper right corner of the dialog box The default value of the TipBiasVoltsOffset parameter is zero Click and drag over the existing value of the parameter to select it then type in the offset value you measured in Step 6 above in volts For example if you measured an offset of 65 mV in Step 6 then change the value of the TipBiasVoltsOffset parameter to 0 065 Press the Enter key on your keyboard to register the change Click the button to close the dialog box The offset in the tip to sample bias is now accounted for in the software Thus the bias you set using the Tip Bias and Sample Bias scrollboxes of the Ima
244. ow to insert STM tips into the STM cartridge WARNING STM tips are very sharp Be careful when handling an STM cartridge with a tip loaded Store the STM cartridge and tip in a container with a lid Inserting the STM Tip into the STM Cartridge You can use a tip that has been made using wire cutters or an etched tip You insert the back end of the tip first Note Itis not necessary for you to be able to see the tip using the on axis optical view since you will mainly be using the side view However if you do want to see the tip in the on axis view then try to have the sharp end of the tip extend out from the STM cartridge about as far as the AFM cantilever chip on the AFM cartridge If the tip is too long or too short you will have difficulty locating the tip using the on axis optical view 2 9 2 10 Chapter 2 STM Imaging 1 First loosen the set screw on the top side of the STM cartridge 2 Grip the STM tip near its middle using a pair of needle nose pliers Feed the back end of the tip through the hole in the underside of the cartridge as shown in Figure 2 6 below The underside of the cartridge is the side with the three embedded silver balls er ja Fe AE Insert back end of tip from the underside ofthe cartridge a Al A LE ae max tip length 0 72 Figure 2 6 Inserting a tip into the STM cartridge Keep fe
245. ow to use it to produce very sharp STM tips If you wish to order a ThermoMicroscopes tip etcher please contact your ThermoMicroscopes representative The components of the tip etcher are listed below the TE 100 STM Tip Etcher electronics unit a 600 ml glass beaker the carbon electrode attached to a lid which fits over the beaker the tip electrode a white cylindrical tip holder which fits through the hole in the lid the cable and power cord Preparing and Loading STM Tips 2 5 You will also need the following items tungsten wire a strong pair of wire cutters a pair of needle nose pliers KOH pellets rubber gloves and protective goggles a glass stirring rod deionized water isopropyl alcohol These components are shown in Figure 2 2 below RATHER TE 190 STM Te ETCHEA Tip Ekctrode Carbon Electrode re Figure 2 2 The components of the tip etcher Setting Up the Tip Etcher l Connect the power cord to the rear of the tip etcher electronics unit and plug it in Make sure the unit is switched off The red POWER light should be off 2 Place the carbon electrode inside the beaker so that the black lid covers the top of the beaker 3 Insert the tip electrode into the opening in the top of the lid Push the tip electrode into the hole so that it fits snugly 2 6 Chapter2 STM Imaging Connect the cable to the connector labeled ETCHER on the rear panel of the ele
246. ponds to changes in topography and how that response correlates with the resulting LFM and AFM data Vertical motion of the cantilever is depicted as a change in the vertical position of the cantilever Lateral motion of the cantilever is depicted as a change in the angle of the tip with respect to the horizontal How Lateral Force Microscopy LFM Works 3 5 a En V ae Cantilever response to 7e FN change in topography e b AFM line trace c LFM line trace V Figure 3 2 Cantilever response to change in topography and corresponding AFM and LFM signal traces Figure 3 2a shows that a change in sample topography creates both vertical and lateral changes in cantilever position The lateral component is not recorded for the AFM image which monitors only vertical bending of the cantilever Figure 3 2b shows the AFM signal trace that would result from the topography of Figure 3 2a Figure 3 2c shows the LFM signal trace that would result from the topography of Figure 3 2a As the figure shows the LFM data reflect only the lateral components of bending e g bending to the right at the rise in topography produces a positive signal and bending to the left at the drop in topography produces a negative signal 3 6 Chapter 3 LFM Imaging Figure 3 3 illustrates how a cantilever responds to changes in frictional coefficients and how that response correlates with the resulting LFM and AFM data Cantilever respo
247. probe head is turned off When you re sweep the response curve of the cantilever and then click the button the phase is re synchronized 1 20 Chapter 1 NC AFM IC AFM and MFM Imaging Performing an Auto Approach To set up for an approach select Approach from the Setup menu This opens the Approach Parameters dialogue box By default the system is set up for an incremental approach Select Quick then click the button to register the change and close the dialogue box Note For details on setting approach parameters refer to the section Setup Approach in Part III Software Reference of this User s Guide Perform a coarse approach by using the z direction pad to lower the probe head until the tip is within a few millimeters of the sample surface Then click the button to initiate an auto approach The first noise you hear is the system lifting the tip before the approach Then the system decreases the tip to sample spacing The auto approach stops when the cantilever vibration amplitude matches that represented by the set point value displayed in Image mode Note If for any reason you want to re select the drive frequency after the system has performed an auto approach you need to lift the tip using the upper z direction pad This positions the tip away from the sample so that its free space resonant frequency can be determined Switch to Image mode to view the Oscilloscope Display If the Topography sign
248. procedures in the following sections describe how to operate in LFM mode You will learn how to generate and view four images simultaneously and how to compare the information contained in those images 3 8 Chapter 3 LFM Imaging Setting up the System Setting up the instrument to operate in LFM mode consists of the following general procedures installing the appropriate hardware configuring the system software aligning the deflection sensor performing an auto approach This section assumes that your instrument has been installed by a ThermoMicroscopes representative and that all of the cables are properly connected If you have the standard AutoProbe CP system configuration This section assumes you are using a 5 um scanner and an AFM LFM probe head If you have the multitask AutoProbe CP system configuration This section assumes you are using a 100 um scanner and the multitask probe head Installing the Scanner and the Probe Head 1 Install a scanner CAUTION The power to the AEM must be turned OFF before you remove or install the scanner CAUTION The four screws that connect the scanner to the CP base unit must be securely fastened to ensure proper grounding When the four screws are securely fastened maximum instrument performance is ensured since vibrations are reduced 2 Place a 1 um gold calibration grating on the scanner sample mount 3 Install the appropriate probe head by sliding it o
249. put Configuration dialog box and return to Image mode 3 In Image mode make sure that the Z Servo box is checked so that z feedback is enabled 4 Click the button to start taking an image This mode of operation generates an image using the signal applied to the scanner in order to maintain a constant tunneling current Constant current mode is used for most STM images Taking an STM Image 2 25 Taking a Constant Height Mode Image 1 Open the Input Configuration dialog box by selecting Input Configuration under the Setup menu Click on Error Signal in the Available list box to select the Error signal then click the button to add that signal to the list in the Selected list box Click to close the Input Configuration dialog box and return to Image mode 2 In Image mode set the gain to a low value Do not lower the gain all the way to zero however A finite gain allows the tip to track slowly varying surface topography for instance due to a shallow slope Some small degree of surface tracking is important because the tip must be within about 10 of the surface to obtain a measurable tunneling current 3 Select a scan rate for example 20 Hz Scan rates used for STM are generally the same as for AFM For atomic resolution images however it is best to use a faster scan rate around 12 to 25 Hz As mentioned earlier in this section faster scan rates reduce the effects of thermal drift in an image While You Are Taking
250. quently You should be able to take an image of that size and see several periods of the features on the sample This tutorial uses a 1 um gold calibration grating as an example since this sample is provided with standard AutoProbe CP systems Ideally however you should use a sample that has features with a spacing similar to features on samples you plan to use regularly since a maximum of only five periods on the um grating can be measured using the 5 um scanner The general procedures outlined here can be applied to whatever calibration sample you use Once you have installed the appropriate hardware you can configure the system software Values for all of the scanner calibration parameters are contained in a calibration parameter file Each scanner in your system has a working scanner calibration parameter file To direct the system to use a particular scanner calibration parameter file select that file when you configure the system software in the ProScan Database Configuration dialog box This can be done at any point during a working session by selecting Configure Parts from the Setup menu or by clicking the Configure Parts icon gt The names of available files are under the drop down list in the CP LS Scanner category of the ProScan Database Configuration dialog box Note The files can also be found in the c psi cal directory A file name for a working file typically includes the size and the serial number of the
251. r board installed in the AutoProbe electronics module AEM BNC coaxial cable for connecting the frequency synthesizer board to the instrument ThermoMicroscopes ProScan Software Note An NC AFM probe head and probe cartridge must be used together in order to take non contact images using AutoProbe CP In addition you should use cantilevers that have been preselected for non contact measurements For MFM you need the following components in addition to those listed above for NC AFM MFM cantilevers with magnetically coated tips Tip magnetizer Non magnetic sample holder These components are available as part of the MFM toolkit that you receive if you order the MFM option Note MFM must be ordered as a separate option Not all AFM NC AFM probe heads for the standard AutoProbe CP system configuration support MFM mode If you are not sure whether your probe head can be used for MFM mode contact ThermoMicroscopes s Customer Support 1 6 Chapterl NC AFM IC AFM and MFM Imaging Taking an NC AFM Image This section leads you through the process of taking and refining an NC AFM image Many of the procedures for taking an NC AFM image are also followed for taking an IC AFM or an MFM image For this reason it is recommended that you read this section before proceeding to Taking an IC AFM Image and Taking an MFM Image which give the procedures for taking IC AFM and MFM images respectively It i
252. r file on a floppy disk After you complete the scanner calibration procedures of 6 30 Chapter 6 Scanner Calibration this section you will be instructed on how to create a backup copy of the scanner calibration file If you need to reinstall your software for some reason be aware that only the default scanner calibration parameter files will be installed in the c psi cal directory the working scanner calibration parameter files will not be installed You will have to copy the working scanner calibration parameter files from the backup copies you have in a different directory By reinstalling the backup copies you will not have to perform a complete scanner calibration again Now open ProScan and set up for taking a contact AFM image 1 Turn on the AEM the computer and the monitors 2 Open ProScan Data Acquisition From Start point to the Program folder and select ThermoMicroscopes ProScan Then click the Data Acquisition icon Alternatively double click the Data Acquisition icon in the desktop The program opens to Move mode 3 Turn off the probe head by either deselecting Head ON from the Mode menu or clicking the Head ON icon 4 Select Configure Parts from the Setup menu Alternatively click the Configure Parts icon The ProScan Database Configuration dialog box will open Note The Configure Parts option is only enabled when the probe head is turned off When the probe head is turned ba
253. r on off switch is located on the front panel of the computer unit The computer monitor on off button is located on the front of the monitor below the screen When you start the computer you automatically enter the Windows desktop 4 Open ProScan Data Acquisition From Start point to the Program folder and select ThermoMicroscopes ProScan Then click the Data Acquisition icon Alternatively double click the Data Acquisition icon in the desktop The program opens to Move mode Taking an NC AFM Image 1 11 5 Turn off the probe head by either deselecting Head ON from the Mode menu or clicking the Head ON icon 6 Open the ProScan Database Configuration dialog box by selecting Configure Parts from the Setup menu Alternatively click the Configure Parts icon gt 7 Configure the system software for a non contact scan To do this make the following selections Head type AFMNCM Scanner Select the file that has the scanner calibration values for the scanner that you are using Head mode NCM Beam bounce cantilever Select the name of the file that corresponds to the cantilever you are using Electrochemistry ON OFF OFF Voltage mode HI After you finish entering these selections click the button to return to Move mode 8 Reset the Z stage as described in Chapter 2 Part I of this User s Guide This synchronizes the position of the Z stage with the coordinate system of th
254. rce gradient experienced by the cantilever increases and its resonant frequency decreases as described above If the resonant frequency of a cantilever shifts then the amplitude of cantilever vibration at a given frequency changes Near a cantilever s resonant frequency this change is large Figure 1 7 shows a response curve vibration amplitude vs frequency for a cantilever If the curve shifts to the left for example then there is a change in this case a decrease in the amplitude of cantilever vibration at a given frequency f change amplitude A in resonant of vibration frequency change in vibration amplitude f frequency Figure 1 7 Response curves for a cantilever showing a decrease in vibrational amplitude at f f for a decrease in cantilever resonant frequency This shift in amplitude associated with a shift in resonant frequency is the basis for the amplitude modulation AM measurement technique used by ambient AutoProbe instruments to detect changes in a cantilever s resonant frequency How Non Contact AFM Works 1 59 For AM detection the cantilever is driven at a fixed frequency near resonance e g f in Figure 1 7 and changes in its vibration amplitude are detected In non contact AFM mode a drive frequency close to but greater than the free space resonant frequency of the cantilever is selected so that the vibration amplitude decreases significantly as the cantilever is brou
255. rect position the red lights are very sensitive and you may find it difficult to position the PSPD so that all of the red lights stay off As long as you are very close to the correct position you can proceed with the lateral force measurements Setting up the System 3 13 Troubleshooting Tips The process of aligning the laser on the PSPD for operating in LFM mode is more difficult than it is for operating in AFM mode This is because LFM mode uses a quad cell PSPD while AFM mode uses a bi cell PSPD For a quad cell PSPD the laser must be aligned in the center of the detector on all four A through D quadrants For a bi cell configuration the laser is considered to be aligned as long as it is hitting the two halves of the detector A and B Figure 3 7 shows aligned laser spots for both quad cell and bi cell PSPD s a b Figure 3 7 Laser spot shaded circle aligned on quad cell a and bi cell b PSPD s If you are having difficulty aligning the deflection sensor you may need to try using a different cantilever Residual strains in a cantilever may cause it to bow slightly making laser alignment difficult If you are using a hand Microlever which has 5 tips per chip then you have several tips to choose from without requiring changing the chip The center tip often works well for taking LFM images If you cannot get the laser anywhere near the detector try the following 1 Try another tip on the chip 2 Try
256. resented by a horizontal red line that cuts across the response curve peak at about half of the maximum peak height This is the default value of the set point parameter You can change this value by using the mouse to drag the horizontal line up or down on the plot The set point parameter can be represented in units of micrometers or in arbitrary units eArbs When represented in arbitrary units the value is a negative number between 0 and 2 The set point value is displayed in the top line of the NCM dialog box as for example Set 0 121 1 For now leave the set point parameter at its default value 2 Click to close the NCM Frequency Set dialog box and return to Move mode You have now set all of the NCM parameters You can also adjust the set point parameter during a scan from the Image mode window Since adjusting this parameter is equivalent to adjusting the tip to sample spacing it is commonly used to optimize the Topography signal trace The absolute value of the default set point is too large for the system to detect sample topography In the next section you will perform an auto approach Then you will incrementally decrease the absolute value of the set point parameter bringing the tip closer to the sample until the tip and the sample come into intermittent contact and the sample topography is represented by the Topography signal trace 1 32 Chapter NC AFM IC AFM and MFM Imaging Performing an Auto Approach 1 To
257. ribed the procedures for calibrating both 5 um and 100 um scanners The topics covered include the following how the scanner works when to calibrate the scanner identification and definition of scanner calibration parameters that are involved in the scanner calibration process scanner calibration procedures The scanner is an important part of your AutoProbe CP instrument Understanding how it works and how it is calibrated helps to ensure that you are optimizing the performance of your instrument
258. rlaubtes Reparieren Ver ndern oder Installieren sind nicht gedeckt durch diese Garantie Garantie von Ersatzteilen ThermoMicroscopes garantiert das alle verkauften Ersatzteile frei von Material und Verarbeitungsfehlern sind Diese Garantie gilt f r 90 Tage ab dem Lieferdatum ThermoMicroscopes repariert oder ersetzt solche Teile nach eigenem Ermessen falls sie zu ThermoMicroscopes zur ck gesandt werden Der Kunde muss ThermoMicroscopes vorzeitig kontaktieren um eine Genehmigung f r die R cksendung des Teiles zu erhalten F r den Transport des Teiles muss den ThermoMicroscopes Transportanleitungen unbedingt Folge geleistet werden xl Vorwort und bersicht Ausser den bis anhin bestimmten Bedingungen ob ausgedr ckt oder stillschweigend angenommen bernimmt der Verk ufer keine Garantie Der Verk fer schliesst ausserdem ausdr cklich jegliche Garantie f r eine Marktg ngigkeit oder Tauglichkeit f r besondere Zwecke aus Unter keinen Umst nden kann ThermoMicroscopes f r Verlust oder Sch digung jeglicher Art haftbar gemacht werden ob direkt speziell indirekt oder Folgesch den welche durch die Ben tzung oder Ben tzungsausfall eines Produktes einer Serviceleistung eines Teils einer Lieferung oder eines Ger tes entstehen Noch soll ThermoMicroscopes unter jeglichem Rechtssystem f r Sch den Einschliesslich aber nicht begrenzt auf wie Profitverluste Stillstandzeiten Firmenansehen Sch digung oder Auswechslung des Ger
259. robe CP If you are using the multitask system configuration align the laser as you normally do as described in Chapter 2 Part I of this User s Guide Then skip ahead to the section Performing an Auto Approach Setting up the System 3 11 To align the deflection sensor you must first steer the laser beam so that it reflects off of the back of the cantilever Then you move the position sensitive photodetector PSPD so that it is aligned with the laser spot This process can be one of the most challenging steps involved in LFM operation At the end of this section troubleshooting tips are included that may help you if you encounter problems while aligning the deflection sensor 2 Bring the cantilever tip into view and turn on the laser Click the Optics View button to turn on the optics view light Bring the cantilever tip into view on the TV monitor Bring the tip into focus using the optics control and the Z stage pads Turn on the probe head by clicking the Head ON icon Turn the optics view light off to see the laser spot Align the laser spot on the end of the cantilever To steer the laser spot adjust the laser beam steering screws Figure 3 5 shows the direction the laser spot moves when you turn the laser beam steering screws You may need to turn both screws at the same time Direction of laser spot in optical view Y Laser beam steering screws Figure 3
260. robe CP Systemkomponenten m ssen mit Vorsicht behandelt werden In den Systemkomponenten befinden sich empfindliche elektromechanische Messger tausr stungen welche bei unsachgem sser Behandlung besch digt werden k nnen VORSICHT Um eine Ber hrungsgefahr zu vermeiden muss beim Entfernen und Installieren des Scanners die Spannung des AEM immer ausgeschaltet sein VORSICHT Der LASER ON OFF Schalter des Tastkopfes muss immer ausgeschaltet OFF Stellung sein bevor der Tastkopf entfernt oder an der XY B hne installiert wird Bei Nichtbefolgen des letzteren k nnen die Laserdioden LEDs des Tastkopfes besch digt werden VORSICHT Um ein besch digen des Scanners zu vermeiden m ssen sie beim Entfernen und Installieren des Tastkopfesopfes ber ein Erdungskabel geerdet sein Der Tastkopf ist sehr empfindlich gegen elektromagnetische Entladungen VORSICHT Um eine ordungsgem sse Erdung des CP Scanners zu gew hrleisten m ssen die vier Schrauben die den Scanner mit der CP Grundeinheit verbinden sicher angezogen werden Wenn die vier Schrauben sicher angezogen sind ist eine maximale Instrumentenaufl sung gew hrleistet da die Vibrationen reduziert sind Betriebssicherheit xxix VORSICHT Um die EMV Best ndigkeit zu gew hrleisten sollte w hrend dem Aufnahmen die CP Grundeinheit mit dem metallenen Deckel geschlossen werden Erdung des AutoProbe CP Das AutoProbe CP muss ordungsgem ss geerdet
261. ron Scanner 6 19 19 Repeat Steps 11 through 14 measuring the distance between grating lines in the x direction of the fast y image to calculate a value for the MicronPerDacSq_SlowSX parameter You should now have values recorded in your table for all four of the second order scanner calibration parameters for high voltage mode Next you will enter these values into the scanner calibration parameter file Editing the Scanner Calibration File 1 From the Move mode window use the z direction pad to withdraw the tip from the sample 2 Turn off the probe head by either deselecting Head ON from the Mode menu or clicking the Head ON icon 3 Select Calibration Edit from the Setup menu Click to indicate that you want to proceed 4 Select the Scanner category in the left listbox 5 Select the appropriate second order calibration parameter For example select MicronPerDacSq FasiSX 6 Change the value of the parameter by typing the new value into the textbox above the Calibration Values listbox Press the Enter key after entering the new value so that the correction is recognized by the software 7 Repeat Steps 5 and 6 for all of the second order scanner calibration values that you wish to change 8 Click to register the changes and close the dialog box After the second order parameter values are changed in the scanner calibration parameter file you should see an improvement in the scan siz
262. roscopy window shown in Image mode When you enter Spectroscopy mode while operating your instrument as a scanning tunneling microscope the software controls that appear are appropriate for acquiring current vs voltage curves When you enter Spectroscopy mode while operating your instrument as an atomic force microscope the software controls that appear are appropriate for acquiring force vs distance curves 5 4 Chapter5 l V Spectroscopy A current vs voltage I V curve is generated using the most recently acquired STM image The STM image is typically acquired using the Topography signal as this signal is representative of the surface electronic structure A current vs voltage curve is generated at a single x y location in an image The scanner remains fixed in x y and z during acquisition of a current vs voltage curve to maintain a constant tip to sample spacing The system sweeps over a specified bias voltage range and measures the tunneling current The next section describes controls of the I V Spectroscopy window If you want to start the tutorial you can skip this section and return to it at a later time l V Spectroscopy Controls 5 5 l V Spectroscopy Controls This section describes the controls in the I V Spectroscopy window see Figure 5 1 The table below lists each control in the window along with a brief description of its function The tutorial in the next section teaches you how to use these control
263. s Table 5 1 Controls in the I V Spectroscopy window Control Function l V Selects an I V curve to be generated at a selected x y location on the sample surface Fromand To Allow you to set the range of bias voltage that is applied to the sample during acquisition of an I V curve The From textbox allows you to set the lower limit of the bias voltage range The To textbox allows you to set the upper limit of the bias voltage range Rate Allows you to set the rate at which the system sweeps the bias voltage range during I V data acquisition Average Allows you to select the number of sweeps that are averaged to generate an I V curve Run Disables the feedback loop and starts ramping the bias voltage to generate an I V curve Once the I V curve has been acquired the feedback loop is enabled again dl dV Differentiates an I V curve This operation can be performed only once for a given I V curve H Horizontal Sets the horizontal scale of an I V or dI dV curve for adjustment V Vertical Sets the vertical scale of an I V or dI dV curve for adjustment Depending on the option button that is selected H or V allows you to adjust either the horizontal or vertical scale of an I V or dI dV curve Zoom Allows you to zoom in on an area of an I V or dI dV curve 5 6 Chapter5 l V Spectroscopy Table 5 1 continued Controls in the I V Spectroscopy window Control Function Measure Allows you to make point t
264. s per scan line Selecting a smaller scan size will only result in adjacent data points containing repeated information For example if the lateral resolution is limited by the x y detector to be 20 nm and a scan size is selected such that each data point covers 10 nm then the z value for two adjacent data points may be repeated For more details about how the above listed factors affect the lateral resolution of your images refer to the section Why You Need Low Voltage Mode Lateral Resolution in Chapter 4 Part I of your User s Guide The information in that section should help you in choosing an optimum scan size 1 Select a scan size Type in a value and then press the Enter key on your keyboard 2 Select a number of data points and a fast scan direction for your image You select the number of data points per image e g 256x256 or 512x512 from the Input Configuration dialog box You select the fast scan direction using the X and Y option buttons of the Image mode window 1 24 Chapter 1 NC AFM IC AFM and MFM Imaging Selecting a Scan Rate In general as the scan size is increased the scanning velocity is also increased a longer line is scanned at the same scan rate so the tip travels faster over the sample Therefore large scan sizes may be better imaged by decreasing the scan rate in order to decrease the scanning velocity of the tip over the sample If the scan rate is set too high the feedback
265. s Wahl Rad in der ben tigte Spannung ein 100V 120V 220V oder 240V 6 Stecken sie das Spannungs Wahl Rad zur ck in seine Position in der Einheit Versichern sie sich dass die gew hlte Spannung im Fenster sichtbar ist 7 Befestigen sie die Abdeckung ber der Spannungs Wahl Schalter Einheit Die Versorgungsspannung sollte nun ordnungsgem ss eingestellt sein Betriebssicherheit xxxi Laser Sicherheit Beachte In diesem Teil beziehen sich alle Darstellungen auf den AFM Tastkopf der standard system Konfiguration des AutoProbe CP ansonsten ist es anderwertig bezeichnet Das AutoProbe CP enth lt eine Laserdiode welche von einer Niederspannungsquelle betrieben wird und eine maximalen Arbeitsleistung von 0 2 mW CW in der Wellenl nge 600 700 nm hat Im innern des Ger tes k nnte eine Diodelaserleistung bis zu 0 2 mW bei 600 700 nm zug nglich sein Das AutoProbe CP sollte nur bedient werden wenn der Scanner Kopf ordnungsgem ss montiert ist WARNUNG Die Benutzung von Steuerungen Reglern oder das Ausf hren von Verfahren anders als bis hierhin beschrieben kann zu Freisetzung von gef hrlichem Laserlicht f hren Bild 0 2 zeigt die zwei Laserwarnungsmarkierungen des Tastkopfes Strickte Beachtung dieser Warnungsmarkierungen ist erwartet CAUTION LASER LIGHT DO NOT STARE INTO BEAM 0 2 mW AT 600 700 nm CLASS II LASER PRODUCT CLASS 2 PER EN60825 1 1994 lt Bild 0 2 Laserwarnungsmarkierun
266. s assumed that you are familiar with the basics of using your AutoProbe instrument such as loading a probe head and a sample This section does not provide the details for these procedures Instead it refers you to other parts of this User s Guide where applicable After completing this section you should be familiar with setting up the system to take an image adjusting scan parameters and optimizing your images and you should be ready to learn how to take IC AFM and MFM images Summary of the Procedure The following steps summarize the procedures for taking an NC AFM image and can also be used as a quick reference Step 1 Set up the system l Connect cables including the BNC cable between the frequency synthesizer card connector on the rear panel of the AEM and the NC Clock connector on the rear panel of AutoProbe CP Z Install a scanner CAUTION The power to the AEM must be turned OFF before you remove or install the scanner CAUTION The four screws that connect the scanner to the CP base unit must be securely fastened to ensure proper grounding When the four screws are securely fastened maximum instrument performance is ensured since vibrations are reduced 6 Step 2 Step 3 Taking an NC AFM Image 1 7 Load a sample Install the appropriate probe head and an NC AFM probe cartridge If you have the standard AutoProbe CP system configuration Install the AFM NC AFM probe head If yo
267. s chapter describes how to acquire force vs distance curves to study mechanical properties at specific x y locations on a sample surface A force vs distance curve is a plot of the force between the tip and the sample as a function of the extension of the piezoelectric scanner tube Using Spectroscopy mode of ProScan Data Acquisition software you can acquire up to sixteen force vs distance curves with a single AFM image Topics covered in this chapter include the following acquiring a force vs distance curve adjusting parameters and zooming in on features of a curve saving and exporting force vs distance data retrieving previously saved force vs distance curves background information about force vs distance curves dimensions and physical constants of cantilevers The first sections of this chapter are tutorials that guide you through acquiring force vs distance data and saving and retrieving that data Then optional sections at the end of the chapter provide you with background information about force vs distance curves These sections describe forces between a tip and a sample and typical features of a force vs distance curve Atthe very end of the chapter you will find cantilever data sheets that include dimensions and physical constants of cantilevers The F vs d Spectroscopy Window The F vs d Spectroscopy Window 4 3 Force vs distance F vs d curves are acquired using Spectroscopy mode of ProS
268. s due to changes in frictional coefficient and those due to changes in topography How Lateral Force Microscopy LFM Works 3 7 The above description indicates the usefulness of side by side AFM and LFM data they provide complementary information By monitoring the LFM signal you can identify the contribution of lateral cantilever bending to a AFM image Conversely having the AFM information available enables you to confirm contrast changes on an LFM image that are due to changes in topography rather than frictional coefficient When you take a scan you can specify whether you would like the fast scan direction to be x or y horizontal or vertical As an image is being taken the scanner rasters back and forth over each scan line in the fast scan direction and then advances to the next line in the slow scan direction Once you have selected a fast scan direction you can also specify whether you would like to view data collected from the forward or reverse sweep of the scanner For example if you choose an x scan you can choose to view data collected from the right to left sweep of the scanner or from the left to right sweep of the scanner or from both sweep directions When you are operating in LFM mode it is often useful to view both AFM and LFM data collected from both the forward and the reverse sweeps of the scanner In this manner you can distinguish between frictional and topographic information as described above The
269. s of curvature for Ultralever tips is 100 A a more than fourfold improvement over the radius of standard Microlever tips On many samples improved tip sharpness translates directly into improved resolution The aspect ratio which is the ratio of tip length to width fundamentally limits the ability of an AFM to measure steep sidewall features and deep trenches that can be characteristic of patterned semiconductor devices and reticles The tip geometry of SizN4 pyramidal tips gives an aspect ratio on the order of 1 1 Ultralever tips are conical in shape and their aspect ratio can be controlled in the manufacturing process Ultralevers have an aspect ratio of about 3 1 A B WA It A 0 6 mm E e 4m o 3 0 3 mm IH 1 6mm C D Figure 4 8 Ultralever chips hold four cantilevers Typical radius of curvature is 100 A Force Resonance Thickness constant frequency L W um N m kHz Type um um B iso 38 10 040 s5 Ee mordre lie ee ee EE 88 101 212 10 0 pc fas is 20 nB 280 Dts et 20 v7 320 k Summary 4 33 Summary This chapter explained how to acquire force vs distance curves using Spectroscopy mode of ProScan Data Acquisition software You learned how to acquire save and re load F vs dcurves In addition sections at the end of the chapter explained the principles underlying force vs distance data acquisition 4 34 Chapter 4 Force vs Distance C
270. se the Error category from the Category listbox Select the STMErrSignalMethod 2 18 Chapter 2 STM Imaging parameter in the Calibration Values box so that the value of this parameter appears in the textbox in the upper right corner of the dialog box If the value of this parameter is not 8 select the old value and change it to 8 now Then press the Enter key on your keyboard to register the change Click to close the dialog box 1 From Image mode select a tunneling current value for the approach by entering a value for the set point parameter For a gold calibration grating start with a value of 1 to 2 nA for the set point 2 Click the Digital VoltMeter DVM icon Ed to open a DVM window Click the button on the DVM window and select the Current signal so that you can view the tunneling current measured by the system Viewing the tunneling current can be useful both during an auto approach and during a scan as it is an indicator of a tip crash If the tip crashes the current displayed on the DVM exceeds the set point value and saturates 3 Set the tip to sample bias by leaving the sample bias at 0 V and entering a value of 0 1 V for the tip bias 4 Set the gain parameter to 5 This value provides enough feedback response to prevent the tip from crashing into the sample but not so much that the system will oscillate Later while you are taking an image you can adjust the gain parameter to optimize the
271. selecting Head ON from the Mode menu or clicking the Head ON icon 3 Select Calibration Edit from the Setup menu Click in the Warning box to indicate that you want to proceed 4 Select the Scanner Det category in the left listbox 5 Select the calibration parameter whose value you would like to change For example select DetMicronPerAdc_SX 6 Change the value of the parameter by typing the new value into the textbox above the Calibration Values listbox Be sure to press the Enter key after entering the new value so that the correction is recognized by the software 7 Repeat Steps 5 and 6 for the DetMicronPerAdc_SY parameter 8 Click to register the changes and close the dialog box You have completed calibration of the xy detector If you have a z height calibration sample proceed with the next section and calibrate the z detector If you do not want to calibrate the z detector you can skip to the section Auto Calibration of Detector Offsets and Scanner Sensitivity and calibrate the detector offsets and the scanner sensitivity Be aware however that the scanner sensitivity is calibrated using the ScanMaster detectors If you do not calibrate the z detector then calibration of the scanner sensitivity in the z direction will be limited to the accuracy of the default value of the z detector calibration parameter Calibrating the Z Detector Calibrating the z detector means calibrating the z detector output sig
272. selecting NCM Frequency from the A Setup menu or by clicking the NCM Frequency icon p Y 2 Set the drive parameter as for taking an NC AFM image The default value of the drive amplitude the drive parameter is 25 Vary the value until the maximum peak height of the response curve is roughly one third of the full vertical scale 3 Select a drive frequency as for taking an NC AFM image 4 Leave the set point parameter at its default value 5 Click to close the NCM Frequency Set dialog box and return to Move mode You have now set all of the NCM parameters 1 40 Chapter 1 NC AFM IC AFM and MFM Imaging Performing an Auto Approach 1 To set up for an approach select Approach from the Setup menu This opens the Approach Parameters dialogue box By default the system is set up for an incremental approach Select Quick then click the button to register the change and close the dialogue box Note For details on setting approach parameters refer to the section Setup Approach in Part III Software Reference of this User s Guide 2 Perform a coarse approach by using the z direction pad to lower the probe head until the tip is within a few millimeters of the sample surface Then click the button to initiate an auto approach The first noise you hear is the system lifting the tip before the approach Then the system decreases the tip to sample spacing The auto approach stops when the
273. ser Safety Note Throughout this section the drawings refer to the AFM probe head for the standard system configuration of AutoProbe CP unless otherwise noted AutoProbe CP contains a diode laser powered by a low voltage supply with a maximum output of 0 2 mW CW in the wavelength range 600 to 700 nm Diode laser power up to 0 2 mW at 600 to 700 nm could be accessible in the interior AutoProbe CP should always be operated with the probe head properly installed WARNING Use of controls or adjustments or performance of procedures other than those specified herein could result in hazardous laser light exposure Figure 0 2 shows the two laser warning labels of the probe head Strict observance of these laser warning labels is required CAUTION LASER LIGHT DO NOT STARE INTO BEAM 0 2 mW AT 600 700 nm CLASS II LASER PRODUCT CLASS 2 PER EN60825 1 1994 gt S Figure 0 2 Laser warning labels of the probe head The left warning label in Figure 0 2 above specifies that the probe head is a Class II laser product per 21 CFR 1040 10 and 1040 11 The right warning label in Figure 0 2 above specifies that the scanning head is a Class 2 laser product per EN60825 Figures 0 3 through 0 7 below show the location of all instrument controls and indicators pertaining to laser operation for AutoProbe CP systems They also show the locations of all laser safety warning labels the aperture label and the compliance la
274. signal the phase of the cantilever oscillation signal is sensitive to changes in the gradient of the force between the tip and the sample The phase however is even more sensitive to these changes and can therefore produce sharper images of boundaries between magnetic regions Note In order to have access to the MFM Phase signal you must have a Materials Analysis Package MAP module connected to your AutoProbe CP system The MAP module is an optional system component that can be used for phase detection microscopy PDM Setting up to take an MFM image using the MFM Phase signal is similar to setting up to take an MFM image using the MFM Amplitude signal 1 Set up the instrument as described earlier for MFM imaging Make sure that a MAP module is connected to your system and turned on 2 Set the NCM scan parameters the drive frequency drive amplitude and imaging amplitude as described in the earlier section Setting NCM Parameters for MFM imaging 3 Perform an auto approach Next you will select the input signals that you wish to view on the Oscilloscope Display You will monitor these input signals as you adjust scan parameters for taking an image 1 48 Chapter 1 NC AFM IC AFM and MFM Imaging 4 From the Image mode window select Input Config from the Setup menu to open the Input Configuration dialog box Alternatively click the Input Config icon E7 5 The Topography signal sh
275. t follow explain these steps in detail and include important hints and tips for optimal MFM operation Setting Up the System The procedures for setting up your AutoProbe instrument for MFM operation are similar to those for NC AFM operation This section describes special instructions that relate to the magnetic sample and tip Refer to the section Taking an NC AFM Image in this chapter for the remaining set up procedures Loading a Sample The standard sample holder provided with your AutoProbe CP instrument contains a magnet that holds the sample mounting disk to the holder Therefore it may create problems of magnetic interference as you take MFM images and it may also damage your magnetic samples For the best MFM results you should replace the standard magnetic sample holder on the scanner with a non magnetic MFM sample holder You may mount the sample e g the piece of commercial hard disk that is included in your MFM toolkit on the MFM sample holder either before or after installing the sample holder on the scanner Unlike the standard sample holder the MFM sample holder does not use a sample mounting disk to hold the sample Instead the sample is mounted directly onto the holder and you should attach the sample in such a way that it can be removed There are at least two ways to mount a magnetic sample to the MFM sample holder Use double sided tape Use the clips provided in your MFM toolkit to clip the sample
276. t of your AutoProbe system The precision of the scanner motion is largely responsible for the quality and reliability of your data Understanding both the scanner s role in producing images as well as how to calibrate the scanner is therefore an important part of operating your instrument AutoProbe CP comes in two system configurations standard and multitask The standard configuration comes with a 5 um scanner and the multitask configuration comes with a 100 um scanner The procedures for calibrating the two scanners are different This chapter is therefore divided into two sections Calibrating a 5 Micron Scanner and Calibrating a 100 Micron scanner You only need to read the section that pertains to the scanner you are using Note Additional scanners can be purchased for either system Contact your ThermoMicroscopes representative for details Within each section the following topics are covered what it means to calibrate the scanner how to calibrate the scanner The first topic provides useful background material that prepares you for performing the scanner calibration procedures for the scanner you are using The second topic is covered in a procedural section comprised of step by step instructions that guide you through the scanner calibration process Background material common to both types of scanners is included in the sections How the Scanner Works and When to Calibrate the Scanner which
277. t the drive or the gain as described earlier in the sections Selecting a Drive Amplitude and Setting the Gain respectively Compare the forward and reverse Topography signal traces for asymmetries When the scan parameters are optimized the forward and reverse signal traces should appear similar and they should be stable and repeatable If adjusting scan parameters does not result in a better image then try changing the cantilever it may not be suitable for your purposes A damaged tip affects the cantilever frequency response resulting in broad flat resonant peaks instead of sharp peaks If the tip accumulates particles after hitting the surface then the extra mass on the tip can also affect the cantilever frequency response Taking an IC AFM Image 1 27 Taking an IC AFM Image This section leads you step by step through the process of taking an IC AFM image Because many of the procedures for obtaining IC AFM images are similar to those for obtaining NC AFM images this section refers you to Taking an NC AFM Image where applicable Itis assumed that you have read Taking an NC AFM Image and are familiar with taking NC AFM images Summary of the Procedure The following steps summarize the procedures for taking an IC AFM image and can also be used as a quick reference Step 1 Step 2 Step 3 Set up the system Set up the instrument as for an NC AFM scan Set NCM parameters Under th
278. t using points you select on a volts vs distance curve Prints the F vs d curve currently displayed on the Spectroscopy graph Opens the Spectroscopy Setup dialog box which includes the parameter settings described below Sets the Z Drive signal as the variable plotted along the horizontal axis of the F vs d graph Sets the Z Detector signal as the variable plotted along the horizontal axis of the F vs d graph The F vs d Spectroscopy Window 4 7 Table 4 1 continued Controls in the F vs d Spectroscopy window Control Snap Out Snap In Average Rate Use Database Value Enter Value Manually Function Ensures that the snap out point is included on a zoomed in F vs d curve Ensures that the snap in point is included on a zoomed in F vs d curve Allows you to select the number of sweeps of the scanner that are averaged to acquire a final F vs d curve Allows you to set the rate in Hz of each extension and retraction sweep of the scanner Instructs the system to use the cantilever force constant ErrSigNewtonPerMeter value currently listed in the database for calibration of the vertical F vs d axis with units of force Allows you to manually enter the cantilever force constant value to be used for calibration of the vertical F vs d axis with units of force 4 8 Chapter 4 Force vs Distance The Piezo Adjustment Bar The Piezo Adjustment bar is ared bar within a blue and white
279. te scanner size For example if you have two 5 um scanners and you wish to create a different scanner calibration parameter file for each scanner make two copies of the file 5um scn and name each copy 5_XXXX scn where XXXX is the serial number of that particular scanner or some other descriptive label Follow these rules when creating a file name Use only letters digits and the underscore symbol in the file name The system is not case sensitive Use a maximum of eight characters Do not change the file extension scn Do not create a calibration parameter file for a scanner of one size from the calibration parameter file for a scanner of a different size For example do not create a file for a 5 um scanner from the file for a 100 um scanner This may cause confusion later if the file is changed during a system upgrade due to coding within the file When you perform the calibration procedures described in this section you will be writing over the calibration parameter values in the working scanner calibration parameter file ThermoMicroscopes recommends that you keep a backup copy of the scanner calibration parameter file in a separate directory in case the working copy becomes corrupted You may also wish to keep a backup copy of the scanner calibration parameter file on a floppy disk After you complete the scanner calibration procedures of this section you will be instructed on how to create a backup copy of the scanner
280. term Specific distance numbers that define the limits of these regimes depend on the specific tip and sample materials being used In the far field regime the gradient of the magnetic force is greater than the gradient of the van der Waals force The dominance of the magnetic force gradient in the far field regime means that the Topography signal a signal that represents changes in the force gradient is dominated by the magnetic properties of the sample surface Thus if you take an image using the Topography signal you can set the scan parameters to position the tip far enough away from the sample that it is in the far field regime and the image will represent magnetic features on the sample surface In the near field regime the gradient of the van der Waals force is greater than the gradient of the magnetic force The dominance of the van der Waals force gradient in the near field regime means that the Topography signal that represents the force gradient is dominated by changes in the topography of the sample surface Thus if you take an image using the Topography signal you can set the scan parameters to position the tip close enough to the sample that it is in the near field regime and the image will represent topographic features of the sample surface How Magnetic Force Microscopy Works 1 63 The simplest way to take an MFM image is to adjust scan parameters such that the tip is far enough away from the sample to position it in t
281. the LED display of red and green lights shows the laser spot s intensity by the brightness of the center green light rather than with a separate column of red lights The goal is to align the detector so that neither of the red lights is illuminated and so that the green light is brightly illuminated Follow these steps to align the deflection sensor 1 Make sure that the LASER ON OFF switch on the probe head is set to the ON position 2 Turn on the probe head by either selecting Head ON from the Mode menu or clicking the Head ON icon Always make sure that the tip is not in contact with the sample before turning the probe head on or off Whenever you turn the probe head off and then back on again a ProScan dialog box appears recommending that you re set the NCM parameters This recommendation is made because the phase adjustment of the cantilever vibration signal may become unsynchronized while the probe head is turned off For now since you have not yet set the NCM parameters click the button to close the dialog box Taking an NC AFM Image 1 13 Focus on the cantilever using the optical view as you normally do for contact mode AFM operation If the laser beam is not reflecting off the back of the cantilever tip then you need to adjust the position of the laser beam Using the two laser beam steering screws move the laser until you can see a red reflected spot on the back of the cantilev
282. the NCM parameters was discussed in a previous section The purpose of adjusting the scan parameters is to obtain stable imaging conditions which depends on obtaining a stable signal trace that is free of glitches tip snap ins and saturated or truncated signals Iterative adjustment of some of the parameters listed below is generally required in order to produce a high quality image size gain rate slope setpoint The design of the instrument supports adjusting all of the parameters listed above in real time during a scan without having to lift the tip Selecting a Scan Size Choosing a scan size can be as simple as selecting a value so that the features you are interested in are represented in reasonable proportions For example if you are using a 1 um calibration grating you may choose a scan size of about 20 to 50 um so that you can see several lines of the grating Taking an NC AFM Image 1 23 However the scan size you select is also one of the factors that determines the lateral resolution of an image Other such factors include the following the effective tip radius the digitized step size of the scanner the x y detector resolution if ScanMaster is enabled the number of data points per scan line e g 256 or 512 As a rule of thumb you should not select a scan size that is smaller than the lateral resolution as limited by any of the above factors multiplied by the number of data point
283. time before initiating the scanner calibration routine For example Calibrating a 100 Micron Scanner 6 37 scan at full range for one or more hours This shakes out residual strains in the scanner Alternatively you may choose to repeat the calibration procedure later after more extensive use of the scanner To initiate the software routine that calibrates the detector offsets and the scanner sensitivity follow these steps 1 From Move mode lift the probe using the z direction pad Contact between the probe and the sample should be avoided because the scanner will jerk and oscillate during the calibration procedure 2 Turn off the probe head if it is on by either deselecting Head ON from the Mode menu or clicking the Head ON icon 3 Make sure you are in high voltage mode by selecting High Voltage from the Mode menu 4 Select Scanner Calibration from the Setup menu This opens the Scanner Calibration dialog box The top option button Calibrate detector offset only is selected by default Click the middle option button to calibrate both the detector offset and the scanner sensitivity Note At some point you may wish to calibrate the detector offset parameters only Select the top option button when this is the case 5 Click the GO button Note If you wish to stop the procedure at any time click the button Calibrating both the detector offset and the scanner sensitivity calibration
284. tintensit t die die PSPD teffen kann erreicht wenn die Reihe der vier roten Lichter erleuchtet ist Die Indikatoren der AFM NC AFM und AFM LFM Tastk pfe sind in Bild 0 4 unten eingezeichnet Bei diesen Tastk pfen ist die maximale Laserlichtintensit t die die PSPD teffen kann erreicht wenn die Helligkeit des mittleren gr nen Lichtes welches eine ver nderliche Helligkeit aufweisst maximal ist laser intensity and position indicators for other probe heads AFM NC AFM AFM LFM probe heads probe heads QO p DET a green analog analog for variable for variable brightness brightness Bild 0 4 Laserintensit t und Position des Indikators der AFM NC AFM und AFM LFM Tastk pfe der Standardsystemkonfiguration Bei der Multitaskkonfiguration ist die maximale Laserlichtintensit t die die PSPD teffen kann erreicht wenn die Helligkeit des mittleren Lichtes welches eine ver nderliche Helligkeit aufweisst maximal ist Eingezeichnet in Bild 0 5 unten xxxiv Vorwort und bersicht Multitask probe heads Pe analog for variable brightness Bild 0 5 Laserintensit t und Position des Indikators des Multitasktastkopfes Laser position indicators Zeigen die Position des reflektierten Laserlichtes das die PSPD trifft an Wenn der Laserpunkt auf dem Photodetektor zentriert ist leuchtet das mittlere gr ne Licht auf wie in Bild 0 4 und 0 5 oben gezeigt wird Bild 0 6 u
285. tion of the features on the sample with respect to the x and y scan directions Earlier it was mentioned that you should try to mount the sample such that the grating lines sometimes parallel to the sample s edges are Calibrating a 5 Micron Scanner 6 13 aligned with the x and y axes of the image Now check to make sure that this is the case For example if you are using the 1 um gold grating sample make sure that each successive row of maxima on the image lines up with the row directly above it not with the row two rows above it The sample can be rotated 45 degrees from its correct orientation and still appear to be lined up with the x and y scan direction so be sure that features of successive rows line up If you are using a sample other than the gold calibration grating make sure that features of known spacing line up along the x and y axes If the sample needs to be rotated lift the tip rotate the sample re approach the sample and take another image Continue this process until the sample is aligned properly Once it is aligned you may want to make a mark on the sample mount for future reference 10 Once you have an image you are satisfied with use the Line Analysis software tools described in the Image Processing chapter of Part III of this User s Guide to measure the spacing between the largest number of maxima for a given direction on the image For example if you can see three maxima on a cross section
286. tion parameter file Open the Explorer and then open the directory c psi cal Make a copy of the default scanner calibration parameter file for the appropriate scanner size For example if you have two 100 um scanners and you wish to create a different scanner calibration parameter file for each scanner make two copies of the file 100um sen and name each copy 100_XXXX sen where XXXX is the serial number of that particular scanner or some other descriptive label Follow these rules when creating a file name Use only letters digits and the underscore symbol in the file name The system is not case sensitive Use a maximum of eight characters Do not change the file extension scn Do not create a calibration parameter file for a scanner of one size from the calibration parameter file for a scanner of a different size For example do not create a file for a 5 um scanner from the file for a 100 um scanner This may cause confusion later if the file is changed during a system upgrade due to coding within the file When you perform the calibration procedures described in this section you will be writing over the calibration parameter values in the working scanner calibration parameter file ThermoMicroscopes recommends that you keep a backup copy of the scanner calibration parameter file in a separate directory in case the working copy becomes corrupted You may also wish to keep a backup copy of the scanner calibration paramete
287. tive Displays 8 Select Layout from the View menu to open the Image Layout dialog box Alternatively click the Image Layout icon En Select the Dual option button to view two Active Displays Select the Quad option button to view up to four Active Displays Once you have made your selection click the button to return to Image mode 9 Optimize scan parameters and click the button to start a scan Taking an MFM Image 1 49 As the images are being taken select the image that represents magnetic features most clearly Taking an Image Using the Magnetic Force Signal The Magnetic Force signal is a signal representing the magnitude of DC cantilever deflection For many magnetic samples the magnitude of the magnetic force between the tip and the sample is dominant over the magnitude of the van der Waals force and it is strong enough to generate a measurable DC cantilever deflection signal To generate an MFM image using the Magnetic Force signal do the following 1 Set up the instrument as described earlier for MFM imaging 2 Set the NCM scan parameters the drive frequency drive amplitude and imaging amplitude as described in the earlier section Setting NCM Parameters for MFM imaging 3 Perform an auto approach Next you will select the input signals that you wish to view on the Oscilloscope Display You will monitor these input signals as you adjust scan parameters for taking an image 4 From the Image mode
288. to load to the Image Gallery and then click the button to close the dialog box The selected image should appear in the Image Gallery 4 Select the image in the Image Gallery a green box will enclose the selected image and then click the button to import the image into the Import View 5 Click the button in the I V Spectroscopy window 6 Use the Buffer scrollbox arrows to scroll through the stored curves The x y location on the image where the curve was taken is marked on the image in the Import View 7 To display the dI dV curve associated with the displayed I V curve click the dl dV option button 5 14 Chapter 5 l V Spectroscopy Summary In this chapter you learned how to generate a current vs voltage curve using controls in of the I V Spectroscopy window You also learned how to adjust the horizontal and vertical scales used to display the curve make point to point measurements on the curve save curves to the image file and redisplay curves Practice the techniques described in this chapter to become more familiar with generating current vs voltage and dI dV curves and to learn about the local surface electronic properties of your samples Chapter 6 Scanner Calibration 6 2 Chapter 6 Scanner Calibration Introduction This chapter describes how the scanner of your AutoProbe CP instrument works and how to calibrate the scanner to maintain its optimal performance The scanner is a crucial componen
289. to check the value of the signal and adjust the position of the PSPD to minimize it To check the horizontal alignment of the PSPD Adjust the forward backward screw to move the PSPD so that the top and bottom indicator lights are both off This adjustment centers the laser spot between the A C and B D or left and right halves of the PSPD When the top and bottom lights are both off the signal representing A C B D called A B by association with a bi cell PSPD should be small IA BI lt 300 mV To check the value of the A B signal open a Digital Voltmeter DVM by clicking the DVM icon EJ Click the button on the DVM window to see a selection of channels or signals and select A B The display ofthe DVM will show the value ofthe A B signal given in volts or millivolts depending on the value Setting up the System 3 15 If the DVM shows that the A B signal is not small then adjust the forward backward screw to move the PSPD until the absolute value of the A B signal is less than 300 mV The laser spot should now be centered between the A C and B D halves of the PSPD When the A B signal is close to zero close the DVM window and click the button The approach should work It is also desirable that the signal representing the difference between the signals from the upper and lower halves of the quad cell PSPD the LFM signal is close to zero This signal which reflects the vertical alignment of the PSPD
290. ton to stop sweeping 18 Now click the button to acquire an averaged F vs d curve that can be saved After an F vs d curve is generated in Acquire mode the system stops automatically and loads the curve into the next available buffer Buffers are filled successively from 0 to 15 If more than sixteen buffers are filled the system begins to overwrite the contents of the first buffers You can scroll through the buffers at any time using the Buffer scrollbox arrows The buffer number for each curve is indicated in brackets in the upper right corner of the graph Adjusting the Horizontal and Vertical Scales of an F vs d Curve If you have followed the steps in the previous sections an F vs d curve should be displayed in the F vs d Spectroscopy window The horizontal and vertical scales of the curve can be adjusted using the Scale scrollbox arrows You can also adjust the starting value of the horizontal and vertical axes using the Offset scrollbox arrows When you expand the scales of an F vs d curve a reduced portion of the curve is displayed on the graph The scanner s sweep range remains the same and the 1000 data points per curve are still taken over the entire sweep range The resolution of the displayed data remains the same since the 1000 points are not taken over a reduced portion of the curve Acquiring Force vs Distance Data 4 19 To expand the scales incrementally using the Scale scrollbox arrows do the following
291. top sweeping The F vs d curve you generate for the calibration procedure should be well behaved That is you should be able to view a substantial portion of the linear part of the curve the part that represents deflection of the cantilever once contact is made with the sample You will use the mouse to select two points on this linear portion of the curve The system will then use these points to calculate a slope value which is used along with the force constant to calibrate volts with units of force You can either use the curve you generate in Run mode for the calibration procedure or you can use Run mode for parameter adjustment only For example you may need to adjust the scanner s sweep range to include a large linear portion of the curve Once you are satisfied with parameter settings you can generate a curve that can be saved in Acquire mode 11 Use Run mode to generate F vs d curves and make parameter adjustments When you are satisfied with parameter settings click the button 12 Click the button to generate an F vs d curve that you will use for the calibration procedure 4 14 Chapter 4 Force vs Distance 13 Select the Measure option button This sets the function of the cursor for selecting points on the curve and enables the Calibrate button Next you will select two points along the linear portion of the F vs d curve These points will be used by the system to calculate a slope value used in ca
292. tting up the instrument for IC AFM are identical to those for NC AFM Refer to the section Taking an NC AFM Image earlier in this chapter Setting NCM Parameters For an intermittent contact AFM image you specify the following scan parameters Drive amplitude drive parameter Drive frequency Imaging amplitude set point parameter These scan parameters are set in the NCM dialog box which is displayed when you select NCM Frequency from the Setup menu Selecting a Drive Amplitude The drive amplitude is the amplitude of the AC signal from the sine wave generator that drives the cantilever to vibrate To select the drive amplitude of the cantilever you use the Drive scrollbox at the top right of the NCM dialog box The number displayed in the scrollbox is a percentage 0 1 to 100 of the allowable applied voltage to the oscillating cantilever Taking an IC AFM Image 1 29 The best IC AFM results are usually obtained with larger oscillation amplitudes than those used in NC AFM operation This is because larger amplitudes i e more resonant energy applied to the cantilever are more effective at avoiding unstable operation due to erratic tip snap ins caused by mesoscopic water layers and unusually large electrostatic effects To select a drive amplitude do the following 1 Open the NCM Frequency Set dialog box by selecting N Sn Frequency from the Setup menu or by clicking the NCM Frequency ic
293. tube moves again measured in microns An additional calibration that should be performed for a 100 um scanner is the calibration of detector offsets When the scanner tube is in its relaxed or home position with no voltages applied to it the detectors should all read positions of zero Thermal effects and changes in the properties of scanner tubes over time however may cause shifts such that the detectors measure non zero home positions These shifts are accounted for by the detector offset calibration parameters which are the measured outputs from the detectors when there are no voltages applied to the scanner tube When you calibrate a 100 um scanner you will manually calibrate the output of the xy and z detectors with distance in microns Then once the detectors are calibrated the system can use them to calibrate the detector offsets and the scanner sensitivity automatically You only need to become familiar with the names of scanner calibration parameters that you change manually For a 100 um scanner the scanner calibration parameters you will change manually are the following three detector calibration parameters DetMicronPerAdc SX This parameter calibrates the xy detector s x output signal with position DetMicronPerAdc_SY This parameter calibrates the xy detector s y output signal with position DetMicronPerAdc SZ This parameter calibrates the z detector s output signal with position Valu
294. tulatif des messages d Alerte et d Avertissement Cette section comprend les messages d alerte et d avertissement auxquels vous devrez tre attentifs chaque fois que vous utiliserez l AutoProbe CP ATTENTION L AutoProbe CP doit tre correctement mis la terre avant l enclenchement de ses composants Le cordon d alimentation principal doit simplement tre ins r dans une prise munie d une fiche de mise la terre Pour les instructions reportez vous la section Mise la masse de l AutoProbe CP dans la pr face ATTENTION Le choix et le contr le de la tension d alimentation doivent tre effectu s avant l enclenchement des composants de l AutoProbe CP L interrupteur pour le choix de la tension d alimentation est situ sur le panneau arri re de l AEM Le s lecteur de tension d alimentation permet un choix parmi les tensions suivantes 110 V 120 V 220 V et 240 V Pour plus d informations reportez vous la section Configuration de la tension d alimentation dans la pr face ATTENTION Ne pas ouvrir AEM ou l unit de base du CP L AEM et l unit de base du CP utilisent des tensions potentiellement dangereuses et peuvent pr senter de s rieux dangers de choc lectrique AVERTISSEMENT ThermoMicroscopes vous demande d inspecter r guli rement les fils conducteurs du syst me AutoProbe CP afin de vous assurer qu ils ne soient pas emm l s d connect s ou endommag s Les f
295. two methods are similar NC AFM tends to outperform IC AFM for soft samples and when the maximum lateral resolution is required on samples with low profile topography NC AFM does not suffer from the tip or sample degradation effects which are sometimes observed after taking numerous scans with contact or intermittent contact AFM Magnetic Force Microscopy MFM Magnetic force microscopy MFM is NC AFM performed with a magnetized tip Magnetic domains on a surface exert either an attractive or a repulsive force on the magnetized tip and MFM maps the magnetic domain structure For example MFM can be used to image naturally occurring and deliberately written domain structures of magnetic materials MFM requires cantilevers that have been coated with a ferromagnetic thin film such as sputtered cobalt The magnetic force between the tip and the sample is often stronger and has a longer range than the attractive van der Waals force which is imaged in NC AFM Thus it is possible to image only the magnetic domains on a sample by keeping the tip far from the surface where van der Waals forces are negligible Required Components 1 5 Required Components NC AFM and IC AFM for AutoProbe CP require the following components AFM NC AFM probe head for the standard system configuration or the multitask probe head Specially designed non contact probe cartridge Box of NC AFM Ultralever chip carriers for non contact mode Frequency synthesize
296. u have the multitask AutoProbe CP system configuration Install the multitask probe head and set the two mode switches on the probe head to the AFM and NC AFM positions Load a non contact chip carrier onto the NC AFM probe cartridge Load the cartridge in the NC AFM probe head Turn on the AEM the computer and the monitors and set up the system software Align the deflection sensor Focus on the cantilever using the optical view Steer the laser beam onto the back of the cantilever tip Adjust the PSPD position until the indicator lights on the probe head show that the position is optimized Set NCM parameters Under the Setup menu of the Image mode window select NCM Frequency to view the NCM Non Contact Mode Frequency Set dialog box Select a drive frequency drive amplitude drive and imaging amplitude set point for the scan Perform an auto approach In Move mode use the z direction pad to lower the tip so that it is close to the sample Click the button to initiate an auto approach The auto approach stops when the cantilever s vibration amplitude matches the value represented by the set point parameter displayed on the Image mode window Enter Image mode to view a Topography signal trace Optimize the set point parameter by iteratively reducing the set point absolute value while monitoring the Topography signal trace and the Z Piezo bar Re approach the sample if necessary 1 8 Ch
297. u may see oscillations or spike like features on the signal trace These features can result if the gain parameter is too high or if strong magnetic forces cause the tip to snap into the sample surface If you see oscillations or spikes increase the absolute value of the set point until they disappear Click the button to start a scan Adjust scan parameters if necessary to optimize the image Taking anMFM Image 1 47 Experiment by using different values for scan parameters such as the gain rate and set point parameters Adjust these parameters iteratively until you obtain the sharpest image of magnetic features on the sample surface With experience you will be able to judge whether to use the MFM Amplitude signal or the Topography signal to obtain the clearest MFM images of particular samples The next sections describe how to take images using two other signal channels of your AutoProbe CP instrument the MFM Phase and the Magnetic Force signal channels Taking an Image Using the MFM Phase Signal The MFM Phase signal represents shifts in the phase of the cantilever oscillation signal with respect to the signal to the actuator underneath the cartridge mount which is the signal that drives cantilever to oscillate For details on hardware associated with non contact image production refer to the section Hardware Components for Non Contact Imaging at the end of this chapter Like the amplitude of the cantilever oscillation
298. ve Amplitude The drive amplitude is the amplitude of the AC signal from the sine wave generator that drives the cantilever to vibrate To select the drive amplitude of the cantilever you use the Drive scrollbox at the top right of the NCM dialog box The number displayed in the scrollbox is a percentage 0 1 to 100 of the allowable applied voltage to the oscillating cantilever The same applied voltage has different effects with each individual cantilever and cantilever mounting configuration Taking an NC AFM Image 1 15 If the drive amplitude is too small then the cantilever will not be sufficiently sensitive to changes in the vibration amplitude during a scan On the other hand if the drive amplitude is too large then the cantilever will be in intermittent contact with the surface Increasing the drive amplitude too much may also cause the response curve to saturate on the NCM Frequency Set plot 1 Open the NCM Frequency Set dialog box by selecting NCM Frequency from the FT T Setup menu or by clicking the NCM Frequency icon 2 Start with the default value of the drive parameter which is 25 3 Click the button in the NCM dialog box This prompts the system to generate a plot of the cantilever vibration amplitude as a function of drive frequency or a frequency response curve for the cantilever The default selected sweep range covers a large portion of the total sweep range so that the system ca
299. ver vibration amplitude changes in response to force gradients that vary with the tip to sample spacing An image representing surface topography is obtained by monitoring these changes in vibration amplitude Since ideally the cantilever tip never touches the sample surface in non contact mode NC AFM is useful for imaging samples of low moduli such as soft polymers and biological materials that can easily be damaged by the tip A further advantage of NC AFM is that samples such as silicon wafers are not contaminated by contact with the tip and the tip is not damaged by the sample Like contact AFM non contact AFM can be used to measure the topography of insulators and semiconductors as well as electrical conductors 1 4 Chapter 1 NC AFM IC AFM and MFM Imaging Intermittent Contact AFM IC AFM Intermittent contact AFM IC AFM is similar to NC AFM except that in IC AFM the vibrating cantilever tip is brought closer to the sample and its vibration amplitude is greater so that at the bottom of its travel it just barely hits the sample surface For some samples this is preferable to full contact AFM because it eliminates lateral forces such as friction and drag that might damage the tip or sample As for NC AFM for IC AFM the cantilever vibration amplitude changes in response to force gradients that vary with tip to sample spacing An image representing surface topography is obtained by monitoring these changes While the
300. vibration Note You may want to set the LP Filter to a number greater than its default setting which is zero but less than 1 for the MFM Amplitude signal An LP Filter setting greater than 0 provides some averaging of high frequency noise For more details on the LP Filter setting refer to the section Input Config The Input Configuration Dialog Box in Chapter 1 Part III of this User s Guide Click to return to Image mode Both the Topography and the MFM Amplitude signals should be available now in the drop down list below the Oscilloscope Display Set the gain to a relatively low value For example you can select a gain value in the range of 0 1 to 1 Note Be careful when setting the gain to low values You should be using a sample that is relatively smooth since the feedback response may not be high enough to track steep features and the tip could crash into the sample surface Select a scan rate and a scan size for the image For MFM Amplitude images you can select a scan rate that is somewhat higher than that for Topography images For example you can select a scan rate in the range of 2 to 4 Hz Reduce the absolute value of the set point and re approach the sample if necessary until the MFM Amplitude signal trace on the Oscilloscope Display is stable and representative of magnetic features on the sample surface As discussed in the section Performing an Auto Approach earlier in this chapter yo
301. ween LFM and Topography Check the signal traces of LFM and Topography Adjust scan parameters to improve the signal traces where needed Set scan parameters such as the scan size scan rate and set point Starting a Scan 1 Click the button to take an image You should see all four images building up in the View display As the images build up note the differences between the LFM and the AFM data 2 AFM left to right and right to left images should look the same LFM images may show features that are not apparent on the AFM images These features represent something sticky on the sample surface Sticky features should appear inverted in LFM left to right and right to left images This is sometimes referred to as contrast inversion In other words a sticky feature will appear dark for the LFM image taken in one direction and bright for the LFM image taken in the other direction Topographic features on the LFM images are identifiable by their bright or dark leading edges followed by dark or bright trailing edges Note the difference between topographic features on the LFM vs the AFM images Take scans of different sizes to find new features or to zoom in on features 3 18 Chapter 3 LFM Imaging Troubleshooting Tips Signal Saturation If the LFM signal is saturating it may be because the cantilever is twisting too much reflecting the laser beam out of the spatial range detectable by the PSPD Ifthe LFM s
302. which the system will sweep through the bias voltage range In the Average scrollbox set the number of times that the system will sweep through the bias voltage range to generate an averaged current vs voltage curve Click the button to begin generating a current vs voltage curve Click the button to save the current vs voltage curve the numerical values of current as a function of voltage to the image file Generating a Current vs Voltage Curve This section describes how to acquire a current vs voltage curve in I V Spectroscopy mode Instructions for generating a dI dV curve are included Take an STM image using the Topography signal as you normally do Open the I V Spectroscopy window by either selecting I V Spectroscopy from the Mode menu or clicking the Spectroscopy icon on the Toolbar Click the button in Image mode This stops the rastering of the probe in the fast scan direction or y By default the I V option button is selected This selects a current vs voltage curve to be generated If the I V option button is not selected select it now 5 8 Chapter5 l V Spectroscopy Select the x y location in the image where you wish to generate an I V curve The green crosshair that appears in the image represents the x y location where the I V curve will be generated By default the green crosshair is at the center ofthe image To change the location of the crosshair move the cursor to the
303. will typically use constant current mode to take images of larger more irregular regions on the sample surface and you will use constant height mode to take higher resolution images of smaller smoother regions of the sample surface Since portions of the sample surface that you may wish to image with atomic resolution are also small flat regions you will typically use constant height mode for obtaining this type of highest resolution image One advantage of constant height mode for taking atomic resolution images is that faster scan rates can be used as mentioned above Another advantage is the exponential relationship between the tunneling current signal used to generate these images and the tip to sample spacing or sample topography Because of this exponential relationship small variations in topography and surface electronic structure are more prominent in constant height mode images Taking a Constant Current Mode Image 1 In Image mode make sure that the Topography signal is available and selected in the drop down list below the Oscilloscope Display It should be available since it is the default signal selection 2 If you need to add the Topography signal open the Input Configuration dialog box by selecting Input Configuration from the Setup menu Click on Topography in the Available list box to select the Topography signal then click the button to add that signal to the list in the Selected list box Click to close the In
304. window select Input Config from the Setup menu to open the Input Configuration dialog box Alternatively click the Input Config icon 22 5 The Topography signal should be listed in the Selected listbox by default Click on Magnetic Force from the list of signals in the Available listbox then click the button to add the Magnetic Force signal to the list of signals in the Selected listbox 6 Click to return to Image mode Both the Topography NC AFM and Magnetic Force signals will be available now in the drop down list below the Oscilloscope Display You may find it useful to view an image taken using the Magnetic Force signal while you are taking MFM images using other signals In any case select the Magnetic Force signal in addition to the other signal s you are monitoring 7 Set scan parameters to values appropriate for the type of image you are taking Topography MFM Amplitude or MFM Phase 1 50 Chapter 1 NC AFM IC AFM and MFM Imaging To make side by side comparisons of images taken with the different signal channels open two or more Active Displays 8 Select Layout from the View menu to open the Image Layout dialog box Alternatively click the Image Layout icon Ein Select the Dual option button to view two Active Displays Select the Quad option button to view up to four Active Displays Once you have made your selection click the button to return to Image mode 9 Optimize the scan
305. with your system and highly oriented pyrolytic graphite HOPG The large easily identifiable features of a gold calibration grating make it a good sample for taking your first image Graphite is easily cleaved and is often used to demonstrate atomic resolution in air Both samples provide a reflective surface that make it easier for you to perform an auto approach The larger size of an image of a calibration grating 5 to 100 um compared to 50 to 100 A for graphite makes it more difficult to obtain because there is a greater likelihood that the tip will encounter surface contaminants However a gold calibration grating is a readily accessible sample and a good image of its surface is relatively easy to identify For these reasons the main procedures of this chapter describe how to take an image of a gold calibration grating Then at the end of the chapter a special section outlines the scan parameters that you would need to change in order to take an image of graphite The three basic steps for taking an STM image are the following 1 setting up the system 2 performing an auto approach 3 starting a scan The first sections of this chapter describe these steps in detail Following these procedural sections is a section that defines two modes of STM operation constant current mode and constant height mode The last sections of the chapter provide information that helps you to optimize your STM images and a brief section provides y
306. wo subsections The first section provides background information that may be useful to you as you perform the scanner calibration procedures If you would like however you may skip directly to the section that describes how to calibrate a 5 um scanner What it Means to Calibrate a 5 Micron Scanner As mentioned in the earlier section How the Scanner Works software correction is used to improve the accuracy of scan sizes for a 5 um scanner Equations are used to more accurately calculate the voltages that are applied to the scanner to produce a desired scan size The parameters used in the equations are called scanner calibration parameters Calibrating a 5 um scanner means to check and if necessary to change the values of scanner calibration parameters Since these parameters describe the scanner s response to applied voltage the procedure is also referred to as calibrating the scanner sensitivity For small scan sizes below about um scanner nonlinearities are not significant The relationship between the scanner s position and the voltage applied to the scanner is approximately linear but the slope of the line can vary depending upon the particular scanner being used the scan rate or the scan direction The parameters used to describe the scanner s behavior in this range of scan sizes are termed first order scanner calibration parameters since the behavior of the scanner is roughly linear The first step in calibrating t
307. you can observe as you zoom in 2 Type new voltage sweep range limits in the From and To textboxes Change the voltage sweep limits so that the range is reduced to cover only the portion of the I V curve that you are interested in 5 12 Chapter 5 l V Spectroscopy Making Point to Point Measurements on an l V Curve When the Measure option button is selected you can measure the horizontal and vertical distances between two points on a current vs voltage curve The measurements are shown by coordinates x y dx dy below the current vs voltage curve Note The procedures described in this section also apply to dI dV curves Try the following for practice 1 Select the Measure option button This enables you to make measurements on the current vs voltage curve 2 Use the mouse to place the cursor over the current vs voltage curve The cursor should change to a black crosshair 3 Use the mouse to move the crosshair to a position on the curve where you would like an anchor point To define this point as the anchor point click the mouse The crosshair will remain at the position where you clicked and the cursor will change to a second black crosshair As you move the mouse the coordinates of the second crosshair X y as well as its position relative to the anchor point dx dy are reported below the graph Saving and Exporting Data The button saves current vs voltage and dI dV curves to the image file Later
308. you optimize the set point parameter as it can mark the boundary between the dominance of magnetic and topographic effects At this boundary point the van der Waals force gradient increases abruptly Even small changes in the tip to sample spacing result in large changes in the Topography signal causing the system to oscillate or resulting in tip snap ins 8 As you click on the up arrow of the Set Point scrollbox to decrease the set point absolute value note that each click of the mouse button changes the third decimal place of the number shown You may find that there is a specific set point absolute value below which oscillations appear on the signal trace If this is the case stop decreasing the set point once you reach this set point value If no oscillations or spikes appear on the signal trace stop reducing the set point once the signal trace is stable and repeatable If oscillations do appear on the signal trace click on the down arrow of the Set Point scrollbox a few times to increase the set point absolute value This backs the tip away from the sample Back off until oscillations no longer appear on the signal trace Note While operating closer to the sample is generally better as it affords higher lateral resolution for MFM mode the lateral resolution is most likely limited by the radius of the coated tip which is typically on the order of 50 nm Thus operating with an average tip to sample spacing outside the van der W

User's Guide to AutoProbe CP - Advanced Processors Technologies

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