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IS4K User Manual

1. 503 J l i L i 06 00 00 PM 06 00 50PM 06 01 40 PM 06 02 30PM 06 03 20PM 06 04 10 PM 06 05 18 PM pe ae EET Communication Initialized O LED OFF LoggmgOFF jenn Figure 18 Temperature Window Main Menu Navigation Minimize or close window Shows signal value Main charting area fo e Noa Status Bar shows if communication has been initialized number of data packages via the COM port whether the LED illuminators on the optical head are ON or OFF and if Logging is ON or OFF Before using this instrument you need to perform other setup steps see the section on Data SAVA T SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 20 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION Managing Graphs and Windows Each of the instrument windows may display a strip chart graph showing the recent history of the measured data Chart data can be analyzed using the Graph Pallet To zoom into the data displayed right click in the graph area and de select AutoScale X and or AutoScale Y This will cause the display to stop displaying new data making it easier to zoom into the data of interest Note Remember to turn AutoScale back on
2. Reflectance Calibration Window Low SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 30 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION SS Cover the LED s so the LED reflection is no longer visible on the video image Wait at least 3 seconds for the reading to stabilize Note Add time of wobble period plus a safety factor if the Wobble Filter is turned on Perform the Calibrate Reflectance Low Value option 1 Click the Signal Value button and select Low 2 Enter 0 0 for the reflectance in Low Reflect for both the 950 nm and 470 nm reflectometer as the reflectance is zero with no substrate reflection 3 Click Get Current Data Set button to set the Low Signal reflectance values This will place the current measured reflectance values into the Low Reflect windows Remove the cover from the LED s to show the LED reflection in the video image Wait at least 3 seconds for the reading to stabilize Note Add time of wobble period plus a safety factor if the Wobble Filter is turned on Reflect 951 30 Reflect 485 00 Syal Reflect Sya Reflect Low 0 00 0 Low 10 00 0 High 1000 00 TED High 1000 00 e Current
3. If manual gain control is active the gain may be conveniently changed on the main Engine window by selecting settings from the pull down menus SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 25 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION Temperature LUT Calibration This procedure loads the proper translation table for generating temperatures from the ratio of the two pyrometry intensities Go to File to ilies Look Up Table JJ Engine Temperature Ref Log File Gain Files Pyrometer Look Up Table o The Pyrometer Look Up Table window will appear SVT Associates Acculemp ne Temperature Reflectometer Configuration Help Ratio Be ase Look up Table File Say E phd my ya i Ale N 400 0 500 0 6000 7000 600 0 92900 0 1000 0 1100 0 Temperature C 4 C Code Lab iew I54K8 Growth_LV Supportltemp_4012 lut a omnc 0 LED OFF Logg Figure 23 Pyrometer Look Up Table Window The factory provided LUT file is generated for a Silicon Substrate radiator from a calibrated silicon substrate target Click Browse and navigate to the temperature LUT calibration file found on the factory calibration DVD See Appendix LUT for further informa
4. the aluminum silicon eutectic point at 577 C is often used to sense the substrate temperature To calibrate the single channel temperature method by other means Go to Configuration to Data Acquisition Setup Configuration Help Reflectance Calibration Data Acquisition Setup Wobble Filter Debug o The Data Acquisition Setup window will appear SVT Associates Acculemp File Engine Temperature Reflectometer Configuration Help Data Acquistion Setup Geometry Factor Averaging 1 Method of temperature Reference y User defined Temperature Scan Timeims 250 Com Port 1 User Defined Reference Temperature C 0 Comm Delay Sec 0 050 Calculated Geometry Factor i g 2 100E 5 Gain Blank Delay 2 000 Set Geometry Factor 7 983E 7 Fixed Geometry Factor Fixed Emissivity amp Geometry Factor Current Emissivity 0 998 Set Emissivity 0 613 Fixed Emissivity Communication Initialized io LED OFF Lagging OFF Figure 32 Data Acquisition Setup Window In the Geometry Factor box 1 Under Method of temperature Reference select User defined Temperature 2 Click Calculate 3 If you know the geometry factor number you want to use enter it in the box and click Fixed Geometry Factor Box to activate it SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Em
5. Communication Initialized O LED OFF LoggingOFF Figure 31 Data Acquisition Setup Window In the Geometry Factor box 1 Under Method of temperature Reference select Two Channel Temperature 2 Click Calculate The single channel temperature channel is now calibrated by means of the ratio or two color channel Note Make sure there is sufficient signal strength available to make a reliable ratio calculation i e temperature gt 550 C SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 34 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION However there are instances where the ratio method is not applicable If the heated surface has a significant difference in the emissivity between the two pyrometry wavelengths then the ratio calculation will be in error For example the ratio measurement for a silicon substrate may be different than a GaAs substrate at the same temperature To properly handle these material differences the ratio to temperature conversion is performed by a look up table LUT that can be altered See Appendix for more information Page 40 Alternately the single channel pyrometry calibration may be performed via other means For example
6. MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 45 of 51 Engines for Thin Film Innovation S gt Te Some typical values for well known semiconductors are listed in the table below VEIGHEN E 0 eV 10E 6 Accurate Temperature Measurement As consequence of above mentioned facts and phenomena a more versatile instrument that combines both measurement methods is desirable The Accutemp Process Monitor provides high end performance over the entire temperature range Below 400 C emissivity corrected pyrometry cannot be used due to lack of black body radiation Bandgap based temperature monitoring is the method of choice At high temperatures bandgap based measurements are impossible due to carrier concentration and radiation intensities Pyrometry is the method of choice In the intermediate temperature regime emissivity corrected pyrometry is used for best results on opaque substrates Precise calibration and repeatability can be achieved with band gap based calibration For transparent substrates bandgap based monitoring can provide a good alternative Once layers become opaque pyrometry can take over for best performance The Accutemp Process Monitor combines both techniques in a single instrument In addition it allows accurate grow
7. www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 4 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION SS ann Introduction Theory of Operation Pyrometry Pyrometry is a method to calculate temperature by measurement of the electromagnetic radiation emitted by surfaces of opaque objects at finite temperatures This effect is described by Planck s Law which describes the spectral radiance R A T as a function of wavelength and temperature 1 2ehc E Fi R a T Where e is the surface emissivity h is Planck s constant c is the speed of light is the wavelength T is the absolute temperature and k is Boltzmann s constant Thus if one knows the surface emissivity and has a well calibrated radiometer the surface temperature may be obtained A black body is an ideal radiator and has e 1 for all temperatures and wavelengths but real materials have emissivities less than one and may not have a constant value for all wavelengths An example of a black body radiance curve for 700 C is shown in Figure 1 4 3 5 5 wo l Y o EE ol l Radiance x10 9 W m 3 sr N li ol l O 6 8 10 12 Wavelength um O N 4 D Figure 1 Black Body Radiance Curve Traditional pyrometry selects a fixed range of wavelengths and measures the emitted radiation intensity over that range The resulting intensity v
8. y o Figure 25 Temperature Window 1 Ratio Temp 2 Select if you want to plot this temperature SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 28 of 51 PROPRIETARY INFORMATION ee n 3 If this is red there is a problem and the instrument cannot plot if it is green the instrument is getting data Engines for Thin Film Innovation Emissivity Corrected Temp Select if you want to plot this temperature If this is red there is a problem and the instrument cannot plot if it is green the instrument is getting data Reflectometer Menu Reflectometer Window Go to Reflectometer to Reflectometer Window Configuration o The Reflectometer Window will appear Reflectometer Window Reflect 950 80 nm Reflect 470 10 nm 0 0652 0 0838 Plot OFF ON Plot OFF ON Cursors x l Caas 5 B GursorO 09 09 49 aM 0 55172 Atine AP 4 Refl9so 7 B cursor1 09 09 59 AM 0 51724 9 80518 Ew Reia gt oH f EEE j i 3m 1 09 09 19 AM 09 15 00 AM 09 20 00 AM 09 25 00 AM 09 31 01 AM Figure 26 Reflectometer Window Click on the cursors icon in the graph pallet Right click on either Cursor 0 or Cursor 1 in the Cursor L
9. 0 e cee ecececececececececececececeeeeeaeaeaees 8 4 Color RS170 Input 24 V DC OPTIONAL ACCESSORIES 220 V power supply Alternate reflectometer wavelengths available Remote External illuminator reflectometer available for non normal illumination Analog output for feedback control SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 38 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION Appendix Index of Refraction Values Below is a list of useful index of refraction values for common substrate material These may be used for reflectometer calibration See Reflectance Calibration on page 29 MEIGIEN 950 nm Index 470 nm Index Silicon 3 67 i0 005 4 32 i0 07 GaAs 3 54 0 08 4 33 i0 44 Ge 4 65 i0 3 4 3 12 4 AlAs 2 974 10 00 3 51 10 00 GaSb 4 3 10 34 4 3 12 3 InAs 3 7 10 43 4 3 i1 8 InP 3 37 i0 2 3 818 i0 5 InSb 4 42 i0 64 3 57 12 2 GaP 3 17 i0 00 3 6 i0 01 GaN 2 37 10 00 2 47 10 00 These values are obtained from the Palik database Handbook of Optical Constants of Solids Edward D Palik Academic Press First edition 1985 2nd Edition 1991 and the Landolt Bornstein tables Semiconductors Group IV Elements and III V comp
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11. 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 32 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION SS n 3 Com Port The RS232 port numbers that will be used to communicate with the In Situ 4000 Process Monitor 4 Comm Delay Sec Sets the polling rate for reading data at the RS232 port 5 Gain Blank Delay Sets the timeout after a gain change is made AGC or Manual This allows the signal to stabilize 6 Save Saves Data Acquisition values Calibration of the Temperature Instrument The temperature instrument can compute temperature in two different ways by the two color or ratio method and single color radiometry The intended use of the In Situ 4000 is to use the two color ratio method to provide the reference calibration for the single color radiometry method The reason for this is three fold 1 There is more noise in the ratio method compared to the radiometric method 2 The two color method only applies to gray body surfaces and is not correct when multiple layer dielectrics are deposited on the surface of the substrate Multiple layer optical interference alters the emissivity at the two different wavelengths and the ratio calculation is then in error Thus the two color method is only useful before thin films are deposited 3 The single color method may be used even
12. 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 24 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION Se DL 1 Click on the Pyrometer C1 950 nm Gain channel File Browse button and browse to the location containing the gain files and load P950_4XXxX gnc where 4XXX is the serial number of your particular optical head 2 Click on the Pyrometer C2 850 nm Gain channel File Browse button and browse to the location containing the gain files and load P850_4XXxX gnc where 4XXX is the serial number of your particular optical head 3 Click on the Reflect C1 950 nm Gain channel File Browse button and browse to the location containing the gain files and load R950 _4XXxX gnc where 4XXxX is the serial number of your particular optical head 4 Click on the Reflect C2 470 nm Gain channel File Browse button and browse to the location containing the gain files and load R470_4XXxX gnc where 4XXX is the serial number of your particular optical head 5 The Gain Files Setup window allows you to enable Automatic Gain Control where the computer determines the need to switch from one of four hardware gain states depending on the intensity of the signals being received Check the box next to Use Automatic Gain Control to activate the system will use the threshold intensity values to cause the software to swit
13. 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 44 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION Theory of Operation Bandedge or bandgap temperature calculation is based on the principle of a semiconductor material s energy gap E dependence on temperature The energy gap bandgap is calculated by the following empirical equation 2 aT E T doping E 0 Bat E doping Where E 0 Energy Gap at 0K a Absorption Coefficient P Fitting parameter forPhonons E doping Fitting parameter for doping E doping is different for different type of materials and must be known in order to correctly find the Energy gap This is done empirically using a LUT similar to the ratio temperature method This look up table tabulates the relationship between bandgap and temperature for determination of temperature The software fits the materials using above equation over the temperature range of interest An example of temperature dependence of the Energy gap of GaAs is shown in Figure 37 Temperature Dependence of Energy Gap 1 6 ing n an A GaAs Energy Bandgap Eg X es NO 1 1 300 400 500 600 700 800 900 1000 Temperature K Figure 37 Temperature Dependence of the Energy gap for GaAs SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie
14. Reflect 951 30 nm Current Reflect 485 00 nm 5 30 7 28 MAXIMIZE the signals by Channel Wavelengths aoina optical head ly f Pyrometer Channel 1 950 nm aoe Ve P D Pyrometer Channel 2 850 nm Get Current Data Set Reflectometer Charewi 1 951 3 nm gt Reflectometer Channel 2 455 nm ave Communication Intigined 0 LED OFF Logging OFF Figure 29 Reflectance Calibration Window High 4 Click the Signal Value button and select High Click Get Current Data Set button to set the High Signal reflectance values This will place the current measured reflectance values into the High Reflect windows 6 Enter the values for reflect 950 nm and 470 nm respectively See Appendix Page 40 Use known reflectance value or data from literature 7 Select Save Calibration to save these settings Keep in mind that viewport coating will affect the reflectometer calibration so routine calibration of the reflectance is advised SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 31 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION Channel Wavelengths The Channel Wavelengths box provides information on your optical head config
15. chamber into the optical head and may cause an errant reading This may be evident when using vacuum instruments with glowing filaments like ion gauges mass spectrometers etc Also radiation from electron beam or effusion sources may also be scattered into the optical head and affect the pyrometry adversely Solutions to this problem may be to use substrates polished on both sides or ensuring pyrometry is performed at high enough temperatures where the semiconductor substrate is sufficiently opaque 3 Ifthe transparent wafer is optically polished on both sides then the normal incidence specular reflectance must be known prior to loading in the vacuum chamber This is because there are now two surfaces which reflect light back to the reflectometer and the back surface if coated with an opaque film will have a much different reflectance than that determined by the substrate index of refraction PROPRIETARY INFORMATION SS n SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 16 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION Focusing Tips The optical head has two different detection branches for detecting both pyrometric radiometry and reflectometry Both of these syst
16. each Pyrometry can measure temperatures from 400 C and higher band gap thermometry is limited to temperatures typically below 650 C due to free carrier absorption and black body radiation Since pyrometry relies on absolute intensity measurement it is affected by viewport coating and stray light from hot sources Using ratio or 2 wavelength pyrometry can eliminate some of the interference problems but during growth is of limited use since emissivity changes are not properly accounted for Transparent substrates such as SiC ZnO and others cannot be measured by pyrometry unless a backside opaque coating is applied to the substrate Bandgap based monitoring relies on the spectral change in intensity as a relative characteristic to determine bandgap As such it is not limited and can be used in these cases However SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 43 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION ee different substrates may require different spectral ranges and detector configurations Double side polished substrates also cannot be measured well with the bandgap based technique in reflection mode due to low light scattering efficiency Pyrometry
17. grey body the ratio of the radiance equation above becomes hc oMkT _ R A T Ay R Ay T Ay TAAT and the ratio is independent of emissivity and the absolute radiometric gain Thus the temperature may be computed from knowledge of only the measurement wavelengths and the intensity ratio An example curve of radiometric ratio vs temperature is shown below in Figure 3 for the wavelengths of 950 nm and 850 nm This feature of ratio pyrometry is very convenient in correcting errors which affect both wavelengths equally such as optical misalignment viewport window coating or an unknown emissivity SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 6 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION Radiance Ratio 400 500 600 700 800 900 1000 Temperature C Figure 3 Ratio of Radiance vs Temperature for 950 and 850 nm Wavelengths The intensity ratio vs substrate temperature will differ for varying substrate materials so the In Situ 4000 system allows the flexibility of a look up table See Appendix LUT section to translate from intensity ratio to reported temperature This look up tabl
18. laser scattering illuminators Viewport Requirement ccccccecceeeeeeeeeeeeees Minimum vacuum viewport size is 2 75 inch Conflat flange at normal incidence to wafer Minimum clear aperture is 33 mm diameter Transmission range 470 950 nm FOCUS Adjustment cc ceecceecceeeeeeeseeseeeeeeenees Manual Operating Ambient Temperature 000 18 C to 25 C lt 2 C thermal drift during use Storage Ambient Temperature 00 00008 40 C to 50 C Relative Humidity 2 0 0 cece eecceeeeeeeeeeeeeeeeeenees Non condensing Power Requirements ccceceecceeceeeeeeeeeeeeeees 120 V 220 V 50 60 Hz wide input Power Cable Length ccccccccsecceeeeeaeeeeeeeeeees 2m NN GIGI cats caceacessitten terns E 3 2 kg not including external power supply POUSING spesies EEE EREE Eana Black anodized aluminum Dimensions ccccceecceeecseeceeccueceeesueccueeseeseesaes 100 x 140 x 90 mm optical head COMPUTER REQUIREMENTS Operating System o nonnnnneennennnnnnnnnennnnennnnnnnnne Windows XP or later Computer Interface ccccccccceeeseeeseeeeeseeeeeees RS232 9 pin D male connector AT standard OPTICAL ALIGNMENT VIDEO SYSTEM Video Camera Output cccccceeceseeceeeeeeeeeaees B W RS170 signal at 60 Hz 75 Q BNC connector CCIR at 50 Hz is also available Video Cable oo ccc cecececececeeeecececeeeseceeaeaeaeaneees 75 QO BNC coaxial cable 2 m length Video Monitor 2
19. the measured temperature is by inserting the temperature value as a comment in the log file After many different temperatures have been mapped out the log file is then easily analyzed to extract a table of ratio and temperature values The new LUT file may then be generated according the following file format The first line in the LUT file must be B74B9D7A 30B7 11D2 AEE0 244611C10000 LUT 1 This signifies to the program that the file is a LUT file Comment lines are inserted with the notation The next non comment line in the file must be the material label line Material Silicon where the two fields are separated by a tab character Next the pyrometer gain range for which this LUT is valid is specified by a line Gain Range 1 where the gain range may be 1 through 4 and the two fields are again separated by a tab You must be aware of the gain range when you perform the temperature mapping measurement The rest of the LUT is a sorted table of ratio values and temperatures values in degrees C separated by tab characters There is no explicit limit to the number of entries in the table Load in the new LUT text file from the Load button in the ratio LUT property page of the Temperature instrument The new LUT will be saved to the default configuration file on the hard disk so it will automatically be loaded each time the program is run SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 U
20. the two virtual substrate indices may be limited in this fashion Therefore if the user must has some a priori knowledge of the film parameters fitting results will benefit significantly Minimum Rate Allowed It is possible for the fitting algorithm to flat line or settle on a seemingly satisfactory fit with a very small lt 0 001 nm sec growth rate The solution is to kick the growth rate to a more reasonable value if it falls below a certain threshold However if the actual growth rate is lower than the threshold the fit becomes ineffective Maximum Parameter Variation These values set boundaries in parameter space beyond which the fitter is not allowed to search This region is defined as absolute values on either side of user s initial guess Performing a Stand alone Fit Standalone fits are useful for performing deposition rate calibrations or monitoring a very thick film growth Prior to start the fit the user needs to select the wave length in the pull down menu Wave Length Fit After that reasonable guesses for the optical parameters of the substrate the film and the expected growth rate are required It is possible to open a previously created setup file to reuse parameters for convenience The fitter uses all data selected between the two cursers Cursor 0 and Cursor 1 in the reflectance chart for its calculations A click on the Run Growth Fitter button starts the instrument and outputs are generated within less than a sec
21. view Figure 15 orange color whereas the reflectometer detectors have a 3 6 degree field of view Figure 15 blue color The video image views the reflectometer view so the dark boundary outside of the central video image corresponds to the limits of the reflectometer field The pyrometer field is approximately 55 of the reflectometer and is centered on the video image Note The inset in Figure 15 shows the alignment when only a quarter of a wafer is used Note there is a fourth electrical connector present on the rear panel which supplies a TTL compatible sync pulse signal for synchronization of external non normal Figure 15 incidence illuminators If you ordered the optional external illuminator follow instructions to install it Locate the external illuminator and the external illuminator cable Mount the external illuminator to a 2 75 viewport The illuminator has one screw to clamp it to the viewport Using the external illuminator ribbon cable attach the illuminator to the In Situ 4000 The DBM9 on the cable attaches to the DBM 9 on the front of the In Situ 4000 and the 10 pin ribbon connector goes to the illuminator The illuminator connector is keyed for proper electrical connection Figure 16 RVA SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc Al
22. view the substrate in the video monitor Additional illumination applied to the substrate may be required for example by a flashlight shining through a spare viewport or the glow from an ionization gauge Focus the image on the video monitor by loosening the objective lens set screw and i Set crew sliding the lens in and out to obtain a focused image of the substrate When trying to view a large polished substrate with no features to observe in the image you may need to perform a focus operation before the substrate is in place and instead focus the image when viewing the substrate heater Ensure that the focus adjustment set screw is secure before continuing Once the substrate area is centered in the video image the reflection of the LED illuminator must be visible in the image Perform additional tilt and translation adjustments of the optical head and or the substrate to achieve a normal incidence reflection Center the image of the LEDs in the video image Note The LEDs used to illuminate the substrate are quite bright and may saturate the video image producing unusual patterns on the screen Be assured this saturation will not damage the video camera electronics and that this image is normal Figure 14 Once aligned the instrument is prepared for temperature and reflectance measurement There are two different fields of view for the two different types of measurements The standard pyrometer detectors have a two degree field of
23. works based upon the Software You will not reverse engineer decompile disassemble or otherwise attempt to discover the source code of the Software except to the extent you may be expressly permitted to reverse engineer or decompile under applicable law SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 2 of 51 Engines for Thin Film Innovation SS 7620 Executive Drive Eden Prairie MN 55344 3677 USA Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com Table of Contents POCO ct arrctncutttatnactiinestuandseuenset antuuahssanedenerinnexaneis stadscuPereadiuiactiabiaenednacet neue Asinsstaentmice EAA 5 EON OF OPE raO e A E tone Soesiaveaasumeneals 5 IN a E E E A E T E A E E 5 TWO COOr F WOME UY rE T TE a A A N E 6 ESSIE eI E E EEE RTN AE A TE PAE A EE E EE E EA N E E 7 Emissivity Compensated Pyrometry cccceccccseeeeceeeeeeeeeeeeeeeeeeeeeeeeaeeeeeseeeeeseeeeeseaeeeseeeeesneeeseeeeeseeeess 8 Problems with Pyrometry Of Semiconductors ceecccceeeeeceeeeeeeeeeeeeeeeeseeeesseeeeeseeeeeseeeeesaeeeeseeeeeseneeess 9 Unpacking ANG INSIANAUOM s c ccsc Gecereates8Qocauened iastanmcentautecetatat a E E EE E DARRE ra a 12 MIT AG aae PEE EE E E E E E EE
24. 21 Gain Files select and change the Gain settings Page 24 Pyrometer Look Up Table select the temperature LUT calibration file Page 26 Exit exits the software application Engine Menu Engine Window displays measurement values and operates the In Situ 4000 unit Page 27 Temperature Menu Temperature Window view temperature signals Page 28 Reflectometer Menu Reflectometer Window view reflectance signals and calculate growth rate Page 29 Configuration Menu Reflectance Calibration calibrate reflectometer intensity signals Page 31 Data Acquisition Setup set up COM port settings and calibrate geometry factor Page 33 Wobble Filter correct for wafer tilt during rotation Page 35 SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 19 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION De Debug service mode of the In Situ 4000 Help Menu View help manual Start Up Screen When you first start up the software you will see the Temperature window SVT Associates Acculemp e Fie Enone Temperature Refectoneter Configuration Hep ik ee S RVA T Ratio Temp Commcted Temp C Plot OFF ON Plot OFF ON
25. E E ETE E E 12 K esta oea A E E E E EEO A E EOR E EA EE T EEEN E ER 13 Mounting Using SVT Associates FIANGC ccccccccseeeeeeeeeeeseeeeeseeeeeseeeeeeeeeeeseeeeseeseesaeeesseeeeeaeeeesaees 14 Electrical Connections ccccccccceececeeecceeeceeeeceeeeeeeeseeeeseeeeseeeeseeeesaeeesaeesea ease eesaueesauecsaeecsusessusessueesueesaeeeaaaes 15 Other Recommended Usage Notes cccccccccceccceeeeeseeeeeeeeeecceeeueeeeeesecseusessesesseueesseesesseusesseneesseeeessensessegs 16 Window Glare SOU CUO aaa es csc etdiek neat a douse E Aa E a cepeouardemeceneesadceuten usecase 16 Use With Smal VIEW DOWNS ssri sisri eaei rar ein N dena reiii arain esindada 16 Use With Transparent Substrates ccccccccccceececeeeeeeeeeeeeeeeeeeeseeeeeeceeae cess cess eeseeeeseeeesaeessneeeeeeneeeees 16 POCUNG NS ace te ete atie tse ear ree era ensaie tania s Seem AEE AAE EE EEA 17 Film Thickness Non Uniformity ssiicietiaersaidindadadwsaarsns ince odaondea Versa cnsaandadiaacendamstrsndlandnirownisbennataner 17 Optical Head lI IAS MM snstvinatraicsd na tedamtalasttiandaawet poansata soutigaitced aha dayan ialustitoaedetateddummbaiatGatceniatctushalaeaiteden tstiubaiiabond 18 SONNIE se epee cin E ei Sc es nos pec eco am tae 9 ore es eas ates patibesenee aut e bercee aes entee dene teaneeaet 19 Software Installation 2 2 ec cece cee e cece eee cece eeee ance sae ee Ae ee Ge eeAAGeesA A eesaa See A ees G sees Gs eesGaeesaaeesaeeEaeEeEaaEREEES 19 PGES
26. ETARY INFORMATION n G Goods being returned for other than warranty repair shall be subject to a restocking charge of twenty 20 percent of the original sales price of the returned item Returning Equipment for Repair or Servicing Before shipping equipment for repair or servicing obtain a Return Authorization Number assigned by SVT Associates Liability Disclaimer SVT Associates Inc takes steps to assure that its published specifications and manuals are correct however errors do occur SVT Associates Inc reserves the right to correct any such errors and disclaims liability resulting therefrom No Liability for Consequential Damage In no event shall SVT Associates Inc or anyone else involved in the creation production or delivery of the accompanying product including hardware and software be liable for any damages whatsoever including without limitation damages for loss of business profits business interruption loss of business information or other pecuniary loss arising out of the use of or the results of use of or inability to use such product even if SVT Associates Inc has been advised of the possibility of such damages SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4
27. F Logging OFF Figure 6 Temperature Measurement during GaN Growth using Emissivity Compensation Problems with Pyrometry of Semiconductors Pyrometry is a well established measurement technique and is successfully used in many applications It has one main feature that makes it attractive for substrate temperature measurement during MBE or MOCVD it is a non contact and vacuum compatible temperature sensing method However as those who have used pyrometry for semiconductor applications know this technique can be fraught with problems which greatly limit its usefulness SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 9 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION Sj LL SVT Associates has recognized the problems with pyrometry of semiconductors and has designed the In Situ 4000 specifically to solve many of the problems preventing pyrometry from being a useful tool for both MBE and MOCVD processes This system combines traditional pyrometry with specular reflectometry to provide a single instrument to monitor both substrate temperature and film thickness in real time Listed below are some of the problems and how the In Situ 4000 overcomes them 1 Substrate t
28. JV SVT Associates Inc Engines for Thin Film Innovation Model In Situ 4000 Process Monitor User Manual THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION OF SVT ASSOCIATES INC AND SHALL NOT BE USED DISCLOSED OR REPRODUCED IN WHOLE OR IN PART WITHOUT THE PRIOR WRITTEN CONSENT OF SVT ASSOCIATES INC 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Engines for Thin Film Innovation PROPRIETARY INFORMATION OTT Notice This manual and the software it describes are considered proprietary intellectual property of SVT Associates Inc and are not to be disclosed to any third party without permission from SVT Associates software License Agreement The software application supplied with the In Situ 4000 Process Monitor is licensed to the user only and may not be transferred to other parties without the expressed written agreement of SVT Associates Inc This program is protected by copyright law and international treaties Unauthorized reproduction or distribution of this program or any portion of it may result in severe civil and criminal penalties and will be prosecuted to the maximum extent possible under law No Modification or Reverse Engineering You may not modify adapt translate or create derivative
29. PEIE E EE T E TE E EE E E E E E EET 19 EUD S E SN e E E E E ean asneseeeonseees 20 Managing Graphs and WINDOWS wii sciscsseisecnciavecsvacexanccsesdecctsviedaedsaseesaaneveadcsvnntenigeeesdieal EEES EEEE enren nErenn een 21 PIE NICU ee A E E E E Supenachaastantonduass 21 Bate lel gle DaO F cho srera E E EA R A E eter ee ERR 21 Electronics Calibration and Gain Filter ccc ccccccceecceeeeeeeeeeseeeeeeeeeaeeeseeeeseeeeseeeeseeeeseeesseeseeeseneees 24 Manual Gain C OM ON ascot ccnneceduicesitcecueceeacecexesankaideaedevensinndel eee dennecadcecetaelicecuchuidtousdacendundsudeeseteecedeeseeexsee 25 Temperature LUT Calibration cccccccccsccccseecceeecceeeecececeaeeesaeecsaceseeeseusesaueeseuessasessusessusessueeseeeeaaaes 26 EAONE MOME ieee en er eee E EE ee ee ee ee 27 Operation of the Engine INStrUMeNt cc cccccecce ec eeeeeceeeeeeeeeeee ae eeeeaeeeeeaeeeeeaeeeeeaaeeeeaaeeeesaneeeseeeeesneeees 27 Temperature WIEN scr tuascncexcuesnsueeneeesssnaniankeuacendenneimexcusirnarenembecpenseunanbashunanesdaciatacmiseixanernietseransmunendaeialeeuigenedas 28 Temperature WINGOW ccccccesccesecceeceseceueeceecaueccueceaeceueesaecsaeesaeesaessaeesseesaessaeeceeetaeeseeeseessaeessensaeeses 28 FREME COMETS NWS AN saoer ea eiaeia eran kaia eiaa reirei eiriaa 29 Reflectometer VV IN GOW wis csedo sete aides ansiundessxeawvenseegandacoueudauettedsosvasduiiesadeasdwi genes bend deniedenedtied eameaneeceteisels 29 CO MTOUE AOR NG GOs i
30. SA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 40 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION 0 6 I I l 1 I 1 1 400 0 500 0 6000 7000 800 0 9000 1000 0 1100 0 Temperature C ffHeader for file of type LUT f GUID Nice Name Version Number B74B9D74 38B67 11D02 AEE6 244611016066 LUT 2 f tab delimited lookup table file First data lines must be f Material lt tab material name f Gain Range lt tab valid range f The column headings are ff PI956 PI856 Temp Deg C Material Silicon Gain Range 14 6 29214 696 4 6 29216 674 1 6 29215 674 2 6 29216 674 3 6 29213 674 4 6 29267 674 4 6 29268 674 5 8 29522 669 8 6 31779 629 8 6 33363 684 6 6 34578 566 8 6 36415 575 7 6 36985 566 5 6 37272 563 5 6 37537 559 8 6 37726 557 2 8 37688 555 1 0 38003 553 5 0 38089 552 2 6 38164 551 2 6 35416 549 6 6 41289 522 9 6 44261 494 7 6 47364 472 8 6 48899 458 6 6 56196 447 2 S AVA T 0 50930 438 6 X 0 51122 431 8 6 51642 426 3 SVT Associates Inc 0 52255 422 1 AYAS CNG 6 52685 418 6 SVT Associates Proprietary Information mAlOi MEceYanceee 0 52232 415 3 2013 SVT Associates Inc All Rights Reserved DESIOEN H 52443 413 2 Page 41 of 51 6 51766 410 7 A Canca AA N A Engines for Thin Film Innovation PROPRIETARY INFORMATION TT
31. The pull down menu Fit Type selects the scope of fit Fix None Fix S Fix N Fix K Fix N S Fix K S Fix N K and Fix N K S Section of the type of fit impacts its results and convergence and is describes later in this chapter Controlling the Fit Another factor influencing the fitter instrument is the Fit Tolerance which acts as a stop measure once the error in fit is below this threshold value In addition the user must provide initial guesses to give the fit algorithm a satisfactory starting place to search for a best fit and a minimum and maximum value The initial values used in the fit can be the values determined from the last fit or any other guess by the user One limitation of interpreting reflectance oscillations is that the fit parameters are not independent from each other for very thin films For example if a film is being deposited with a current thickness corresponding to less than 1 4 optical wave the fit algorithm can find a satisfactory fit for many different combinations of the six possible parameters which leaves little useful information for the user As the film becomes thicker there is more information available to the fit algorithm and the fit parameters decorrelate and allow meaningful interpretation of the results The Growth Fitter algorithm has an adaptive fitting feature which allows the user to still gain meaningful results in the early stages of growth The Growth Fitter holds the film n and k parameters consta
32. ___ Figure 35 Example LUT File SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 42 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION Bandgap Based Temperature Measurements Introduction Emissivity corrected pyrometry relies upon measurement of surface black body radiation as long as temperature is high enough and the substrate is opaque To overcome this limitation the In Situ 4000 Process Monitor provides bandgap based thermometry as add on Band edge based thermometry utilizes the temperature dependence of a semiconductor bandgap to determine substrate temperature A typical setup is shown in figure XX Lighted Source Diffuse Reflected A AccuTemp N Receiving Head ta JBandgap Detector Figure 36 For higher temperatures substrate heater radiation can be used to determine bandgap for low temperatures an auxiliary light source needs to be used In the first case scattered transmitted light and the latter case diffuse reflected light is analyzed in the Receiving Head Both emissivity corrected pyrometry and band gap thermometry work well for GaAs InP and Si substrates however the general usable temperature range is limited with
33. adiated light from a substrate heater located behind the substrate will be transmitted through the substrate and enter the radiometer The radiometer cannot distinguish between radiation from the substrate and that transmitted through the substrate and a pyrometry measurement error will result One solution to this problem is to coat the backside of the substrate with a sufficiently opaque metal coating 1 Semiconductor substrates have varying transparency with temperature Many semiconductor substrates are partially transparent at 850 and 950 nm at low temperatures At higher temperatures typically the band gap shifts to longer wavelengths and the substrate becomes acceptably opaque The wavelengths used in the In Situ 4000 were chosen to be opaque for silicon GaAs and InP substrates at elevated temperatures Silicon for example is partially transparent at 950 nm below about 550 C and so pyrometry measurements may be adversely affected at lower temperatures Depending on doping levels GaAs substrates can be partially transparent up to 600 C When the substrate is transparent the effective emissivity will be low yet the emissivity measurement will not be correct since the emissivity calculation is based upon the assumption of opaque substrates See Figure 7 2 Ifa substrate is transparent the backside texture of the substrate is visible to the pyrometric radiometer A non polished back surface will then scatter stray light in the deposition
34. ail sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 35 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION SS Ann Fixed Emissivity and Geometry Factor box 4 The In Situ 4000 can be operated as pyrometer without emissivity correction In this case enter a value for set emissivity 5 Select the Fixed Emissivity check box Now the temperature is calculated only by using the 950 nm pyrometer channel This method is useful for non specular substrates or when the refectometer cannot be calibrated The single channel temperature channel is now calibrated by means of the User defined Temperature Other methods such as Oxide desorption can also be used Wobble Filter Many thin film processes utilize substrate rotation to help produce more uniform thin films This mechanical motion can produce strong errors in the reflectance measurement if the surface tilts when rotating If the substrate is mounted such that the axis of rotation deviates from the surface normal by more than 0 5 degrees then the reflection of the LED illuminators will appear to move around the video image and the measured reflectance will vary If the tilt is large enough then the LED reflection will completely leave the field of view and the reflectance measurement will fall to Zero Substrate A special software filter has been implemented to address th
35. amount of light the 1 R relation is no longer true If the deposited film is not uniform then the reflectance measurement made at a single point on the substrate may not be well correlated to the pyrometry measurement made over a larger area of the substrate The three techniques of single color pyrometry ratio pyrometry and specular reflectance are combined in the In Situ 4000 temperature instrument The single color pyrometry temperature measurement is the preferred method because it has better noise performance than the ratio method The 950 nm reflectometry allows calculation of the varying 950 nm emissivity resulting in emissivity compensated pyrometry Since there are instrumental and alignment errors in measuring absolute radiometry the single color method actually calculates temperature based on previously measured radiation at a Known temperature Future calculations of temperature are made relative to the single reference measurement In the In Situ 4000 the reference brabration may be made using the ratio method or through some other method such as oxide desorption or a eutectic temperature measurement See Calibration of the Temperature Instrument chapter SVT Associates AcculTemp File Engine Temperature Reflecbometer Configuration Help Emissivity S RA T Ratio Temp Corrected Temp Red Without Correction s ESGLAIS a P Blue With Correction C Plot OFF ON Plot OFF ON Communication Initialized O LED OF
36. and the emissivity is different between the 950 nm and 850 nm wavelengths In fact not only is the emissivity different but the emissivity ratio for those channels will be different for different substrate materials and will even change with temperature Rather than trying to compute the emissivity ratio to temperature response from first principles a more practical method is to empirically measure the ratio for each substrate of interest The resulting measurement is captured in a LUT The ratio LUT is a series of discrete ratio temperature data points from which the Temperature instrument linearly interprets temperature A factory calibrated ratio LUT for a silicon substrate is provided with the instrument Alternate substrate materials will require the user to generate a LUT specific for that material Making a new LUT requires that the user perform a pyrometry ratio measurement simultaneous with an independent temperature measurement such the aluminum melting point measurement See page 33 Calibration of the Temperature Instrument Other temperatures can then be used with the pyrometry 950 nm single channel temperature Mapping a new LUT You may generate a new LUT by recording the ratio measured by the Temperature instrument and measuring the substrate temperature through some independent means such as a thermocouple The log file of the Temperature instrument provides the ratio measurement to the user and a convenient method for recording
37. ate is high enough to provide a measurable signal Typical substrates such as silicon GaAs and InP are sufficiently opaque at 950 nm for substrate temperatures typical of epitaxial growth The condition of substrate opacity may break down for some low temperature processes where the band edge may shift close enough to 950 nm to cause some problems Therefore the user must be careful to ensure opacity of the substrate at the temperatures of interest 2 Band gap shifts The band gap of a semiconductor substrate is a strong function of temperature and so the basic assumption of constant emissivity made by standard pyrometers is not valid See Band Gap based AccuTemp in the Appendix An example of In Gaj _ N Al Gaj N is shown in Figure 8 Using emissivity corrected pyrometer allows compensation for emissivity layers SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 10 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION Se L_LLLL Indium Molefraction 0 0 2 0 4 0 6 0 8 1 Band Gap Energy In Ga N ev Band Gap Energy In Ga N ev 0 0 2 0 4 0 6 0 8 Aluminium Molefraction Figure 8 Dependence of band gap on Al and In mole fractions Viewport coati
38. ay light introduces an error into the measurement usually causing a higher than actual reading Multilayer interference effects When thin films having different index of refraction from the substrate are deposited the resulting interference effects cause the radiated light to rise and fall with the film thickness even if the actual temperature is constant This causes temperature measurement errors during film growth and can cause actual temperature fluctuations due to non constant radiative cooling of the substrate SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 11 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION Unpacking and Installation Unpacking The In Situ 4000 Process Monitor consists of the following components Part Number Description 5038705 Optical sensing head 5034399 Wall mount power supply or a dedicated rack mount controller 5022756 Computer interface cable 500834 Video cable Software application DVD 5036126 Optional remote illuminator Unpack all components and remove any protective wrapping Please save the shipping material for future use if the unit must be returned to SVT Associates Caution The optical head is construct
39. can wcneaetacsntanteteantadacensndectansdnbisuntendehestanlecatusnetaddeasens E a E 30 Calibration of the Reflectometer Instrument cccceccceececeeeeceeeeeeeeeeeeeeseeeeaeeeese cess eesaeeeseeeeseeeeaeeeeaes 30 Reflectance Callibration ccccccccccscccceccceececneeceeeeseeeeseueeseueeseeessaeessaeessueessaeesaueesaeeesaeeesaeesgeeseusesneess 30 Channel VV AVC SUMS osatanctrcandantetndseKeauntciesnantaieiea cvagsaeatinan Vasari caaidssenmannameniaaapians snipe iapabienont saatuada wane 32 Data Acquisition Setup i cderesccrnsnctecd cncstecacnadalnwtaateiadite xbeveesaiestiteedonsssaenawsbdadeeicdcaiadeabedenscoedteieedeteatedeevee 32 Calibration of the Temperature Instrument cccccceccceeccceeeeeeeeeeeeeeseeeeeeeeeaeeeeseeesaeeesseeeseeeeseeeeaeeeeaes 33 WOO FS Maer tarncttrceatiee ee AEAEE AEAEE A AEE raS EEES SA 36 SPeciNCaUONS ccs ccttesexadcetecscseanesedeiecansisabsceundrachscethcstencatehtacccadubecantsanbinenndnsatinadsensasnosdsaedenndbbeceedasehacsnedncosiasceniss 38 PRC es erates nena eete cate ence E E colenedcadunmiuieediantdcuubdetebigabustanceltixadend E E 39 PROPRIETARY INFORMATION SAAT SVT Associates Inc In Situ Process Monitor Version 2 0 4 13 SVT Associates Proprietary Information 2013 SVT Associates Inc All Rights Reserved Page 3 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION Index Of Refraction ValueS ccccccccsecccsececeeeececeececeeeeeecsecesen
40. ch to a higher or lower gain Changing from one gain state to another takes a few seconds and will prevent the acquisition of data during that time Automatic gain control is recommended for the Pyrometry channels as the range of detected signal varies by several orders of magnitude as the temperature changes Manual gain control is often sufficient for the reflectometry channels as the expected changes in reflectance are not as large Since the signal intensity for the pyrometry channels are always near each other the gain control for both the 950 nm and 850 nm channels are forced to be the same at all times Manual Gain Control Each of the four detection channels allows varying ranges of electronic gain depending on the intensity of the signals reaching the instrument The two pyrometry channels channels 1 and 2 and channel number 4 each allow four different gain settings labeled 1 to 1000 and channel 3 allows two gain settings labeled 1 and 10 The In Situ 4000 Engine instrument allows the user to manipulate the gain ranges of each channel by clicking on the handle and selecting the desired gain See Engine window The signal values displayed in the Engine Instrument window are the measured intensities in mV For optimum signal to noise ratio the following gain ranges are recommended Intensity mV Gain Setting If the gain range is set too high then the electronic amplifiers may saturate so one must use manual gain settings with care
41. debug mode is enabled the 950 nm pyrometry channel displays the intensity of SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 27 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION the outgoing 950 nm LED the 850 nm pyrometry channel displays the intensity of the outgoing 470 nm LED the 950 nm reflectance channel displays the internal temperature of the optical head in C and the 470 nm reflectance channel displays the amplitude of the optical chopper Please consult SVT Associates for diagnostic help if needed 6 Reset Communication button In case the software lost communication to the optical head click the Reset Communication button to reset the COM port It will flash the COM buffer and restarts communication You can also toggle the power handle to achieve the same result Temperature Menu Temperature Window Go to Temperature to Temperature Window SVT Associates Acculemp re stoke IGS ASRS CEST ER Emissivity S R7 oe Ratio Temp Corrected Temp saa foo Nal ie 2m C Plot OFF ON er Plot OFF ON 03 I j l L I 06 00 00 PM 06 00 50PM 06 01 40 PM 06 02 30 PM 06 03 20 PM 06 04 10 PM 06 05 18 PM Communication Initiazed OO OOO
42. e MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 22 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION __SYT Associates AccuTemp PATEN TA STATAN ie Fe ee T Td ve A L X m m mm File Engine Temperature Reflectometer Configuration Help Ui z pao ON ot Fon Pa aa ee pen gt Log Fie Path oneni 3 Desktop ios Log Interval My Documents Communication Iritialized tee Ay Figure 21 Log File Window Enter a name for the file The file will be saved as a text compatible file txt Select where you want the file saved Click OK Logging is now active To turn logging off click the green Logging button The Status Bar shows if logging is activated or not ON OFF i oe SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 23 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION TT _____ Electronics Calibration and Gain Filter When installing and running the software on the computer for the first time the factory calibra
43. e can be changed for different substrates or updated to compensate for any calibration errors or instrument drift The ratio pyrometry feature of the In Situ 4000 provides the user with a repeatable day to day calibration which is independent of viewport coating effects Reflectance In addition to accurate pyrometry the reflectometer feature of the In Situ 4000 Process Monitor measures specular reflectance at two wavelengths 950 nm and 470 nm The reflectometer uses two LEDs housed in the optical head to illuminate the wafer through the vacuum viewport window and Heater detects the light with the same optical system as the pyrometer me War Thus the system needs only a single normal incidence viewport J that is provided in many vacuum systems The viewport must be chamber large enough to allow room for both the illumination light to enter and the reflected and pyrometric radiated light to exit the chamber e Pyrometry The In Situ 4000 requires a 2 75 inch Conflat viewport or larger to accomplish this measurement Another requirement is that the Hezd viewport window is located at normal incidence to the substrate so Video Image B that the illumination beam is specularly reflected back to the a instrument This places some limits on the substrate holders which need to maintain normal incidence alignment during use and especially during wafer rotation The In Situ 4000 system has special software feature
44. ed down by the time specified in the filter period The entered value is the period of rotation of the substrate After several rotations the unit automatically calculates the period Note Press enter after entering a value to activate the wobble filter SAA T SVT Associates Proprietary Information 7620 Executive Drive Eden Prairie MN 55344 3677 USA 2013 SVT Associates Inc All Rights Reserved Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com In Situ Process Monitor Version 2 0 4 13 Page 37 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION SS n Specifications Temperature Range ccccccceceeeeeeeeceeeeeeaeeees 450 850 C or 500 1200 C others on request Compatible Substrates ccccccecceeeeeeeeeeeeeees Silicon GaAs GaSb InP Sapphire backside coated Radiometer Wavelengths ccccceeeseeeeeeees 950 nm 850 nm Temperature Equivalent Noise ccceceeee lt 0 5 C RMS at 450 C 0 05 C RMS at 600 C Target Distance Range cccccecccceeeeeeeseeeeeeees 400 mm to infinity Pyrometry measurement Spot on Target 20 mm diameter at 500 mm target distance Reflectometer Field of VieW ccccceeceeeeeeeees 3 6 degrees Auxiliary Output cece eececeeeeeeeeeeeeeeeeseeeeaees TTL signal of internal chopper waveform to allow synchronization to external reflectance illuminators or
45. ed using a strong outer enclosure and is quite rugged However it is a precise optical instrument and must be treated with care Dropping the instrument on the floor or other rough treatment may cause damage which is not covered under warranty SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 12 of 51 Engines for Thin Film Innovation SS Aan Mounting Typically you can use the flange mount provided by SVT Associates to mount the In Situ 4000 unit However the optical head has two standard tripod mounting holes located on the bottom of the unit Either or both of these holes may be used to mount the optical head on a tripod or other mounting bracket These holes are machined with 74 20 inch threads which are also compatible with standard opto mechanical mounting hardware from suppliers of optical hardware PROPRIETARY INFORMATION Tri Pod Mounting Holes e Mechanical stability is very important in using this system so ensure that the optical head is rigidly mounted and will not move or vibrate during the entire intended use of the product Also the instrument requires a precise pointing alignment to the wafer under measurement so the mounting system should include adj
46. eeseeeeseeessaeessesecsuseseueeseueeseueesaeessesesseeeees 39 EUM NERIO E10 i iemeerse nes ener eee E eee ne ee ee ee ee ee 40 Mapping a new LU W iscccecranincnetueshesencdunenscearaiteacametenderaditud setemabiaahcdusatanaumnasinonatieeeieaciuascsurehanentiedandenste a 40 Bandgap Based Temperature MEaSUreMe nts cccceecceeeceecceeeeeeeeeeeeeeeeeeeeseeeeaeeseeeseesaeeseeesaeeseeeseeeseeeanes 43 IPOCIICUION sessar arr E EE E EE aA 43 WAGON On Op ra UON ai A E E E A 45 Accurate Temperature Measurement cccccccceecescccececeeceececeeeceecueecaeesaeessuesaeeseeecsueseeecseesaeeseeeseas 46 POW RAE FIET petted E E E N e E 47 SOUD er E E E E casein Se eaeee eee 47 Controlling te F iersrere pren RE AE AEE ASE AEREE nid seausuaasted 49 Performing a Stand alone Fl cissstccsetinduicandenicetaindatatandeuasiuiaddovsnbawndsaniisidedieeidaduiwidunandendtirdbeeastsentonns 49 Warranty and Limitations Of REMEIES ccceccccceeeeeeneeeeeee cesses eeesaeeeesaeeeesaeeeeseeeeeseeeeeseeneesseeeesseeeesaneeesaaaes 50 PST UNG EH OUGY eE E E E E enue nmcstnrnienienceeahicesatsb Asean tetas levee taanecasteents 50 Returning Equipment for Repair or Servicing ccccccceeccceeeeceeeese cece eeeeeeeseeeeeeeeeeeeeeseeeeseeeeaeeeeeeeeeaeeesaeeesaeees 51 SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com
47. egend and select Bring to center Click and drag the cursor to the point of interest amp YS When both cursors are positioned in the window the A Time window will display relative time between the cursors Note Calibration is required prior to use See Reflectance Calibration SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com In Situ Process Monitor Version 2 0 4 13 SVT Associates Proprietary Information 2013 SVT Associates Inc All Rights Reserved Page 29 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION Configuration Menu Calibration of the Reflectometer Instrument The specular reflectance is computed from the raw reflectometer data and is displayed in the Reflectometer instrument graph Both the 950 nm and 470 nm channels are displayed simultaneously and the graph axes are manipulated in the same manner as previously discussed The reflectometer measures reflected light in millivolts and two calibration steps must be performed to allow the translation to specular reflectance The instrument must be provided two cases of Known reflectance to compute specular reflectance Typically this is performed with a zero reflectance case and the known reflectance of the substrate under measurement The zero reflectance case can be performed with the substrate missing i e the re
48. ems focus at the same distance however there are two different cases one may choose to optimize focus 1 at the substrate or 2 on the LED illuminators which is twice the substrate distance Focusing at the substrate creates the smallest possible measurement area for pyrometry however the LED image is out of focus and blooms to a relatively large size This large size may cause the reflectometer to become more sensitive to substrate tilt errors Tilt error effects are minimized when the system is focused at the LEDs to make the LED image as small as possible This method causes the pyrometry sensor to be defocused and will sample an area larger than the 2 degree field obtained when focusing at the substrate See Optical Head Alignment Chapter Optimize Focus Substrate Optimize Focus LED Thus for large area substrates the best performance is obtained by focusing at the LEDs because the larger than normal pyrometry sensing area will still be contained within a large diameter substrate However for small area substrates the best performance will likely occur when focusing at the substrate to ensure the pyrometry is measured within the boundaries of the substrate surface Film Thickness Non Uniformity The computation of emissivity based on the measurement of reflectance is made based on the assumption of uniform film properties across the substrate If the film thickness for example varies substantially across the substrate then t
49. end of the serial cable to the 9 pin Computer Interface connector on the rear of the optical head Connect the other end of the serial cable to an available serial port RS232 on your computer Be sure to fully tighten the connector screws on both ends to ensure a reliable data connection Locate the video monitor and set it at a convenient location to the optical head Connect the coaxial video cable from the BNC video signal connector on the rear of the optical head to the video input connector on the video monitor Plug the video monitor power cord into the wall power outlet Make sure the power switch on the optical head is in the off position then plug the round power cable connector into the power connector of the optical head and plug the power supply into the wall power outlet A dedicated rack mount controller might be provided The optical head may now be powered on and is ready for use SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 15 of 51 Engines for Thin Film Innovation Other Recommended Usage Notes Window Glare Reduction The LEDs that direct light at the substrate for the reflectometry measurement can also generate unwanted glare from the viewport window through which
50. es shall be subject to the following conditions A The CUSTOMER must make notification to SVT Associates within thirty 80 days of original shipping date B A RETURN GOODS AUTHORIZATION number must be assigned to and accompany all goods or materials being returned by the CUSTOMER to SVT Associates SVT Associates must assign said number prior to any and all returns Goods not accompanied by a RETURN GOODS AUTHORIZATION number will be refused by SVT Associates and returned at the CUSTOMER S expense CUSTOMER shall prepay shipping charges for products being returned to SVT Associates D Products being returned to SVT Associates should be properly crated for shipment and the CUSTOMER shall bear the risk of loss until delivered to SVT Associates E Products being returned to SVT Associates must be returned in the condition originally received by the CUSTOMER and free from damage use or modification which would render the product unusable for resale by SVT Associates F All applicable taxes duties insurance and shipping charges shall be the sole responsibility of SAVA T SVT Associates Inc O 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 50 of 51 Engines for Thin Film Innovation PROPRI
51. f an opaque substrate a perfectly specular substrate front surface and perfect uniformity of the deposited films the emissivity may be measured via reflectometry at the same wavelength as pyrometry The relation linking emissivity and reflectometry R under these conditions is 1 R The In Situ 4000 provides a 950 nm reflectometer which is matched to the 950 nm pyrometry system thus allowing this emissivity compensation to provide an emissivity independent temperature measurement Thus if the film being deposited has a different optical absorption at 950 nm and or has a different index of refraction as the substrate producing interference SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 8 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION LL effects reflectometry will observe these changes and the software will correct the error in the temperature calculation The success of this technique depends upon how closely the material system conforms to the assumptions listed above namely substrate opacity surface specularity smoothness and film uniformity If the substrate is not sufficiently opaque or the surface is rough and scatters significant
52. f refraction The Growth Rate Fitter instrument fits a model of the oscillations to the data in real time to determine the film s optical parameters and growth rate The fitter can analyze the reflectance data from both reflectometer channels The acquired data the model data and the parameter values are all displayed in the instrument s window 1 See for example W G Breiland and K P Killeen J Appl Phys V 78 p 6726 1995 Setup Reflectometer Window Reflect 951 30 nm Reflect 485 00 0 0000 0 0000 Plot OFF ON 12 46 52 PM me pain SF 12 47 41 PM X 24 omi Refl 470 AZ I 1 i 06 00 00 PM 06 00 01 PM Growth Fitter Outputs Growth Fitt pial i Fit Tolerance Figure 39 Growth Fitter Window SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 47 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION SS n The Growth Rate Fitter instrument is installed on the computer during the In Situ 4000 installation procedure It will appear in the lower window of the Reflectometer Window In order to make use of the Fitter several input parameters are required to control the fitting algorithm These parameters are located on the left
53. fects in material and workmanship and conform to COMPANY specifications No warranty is provided by SVT Associates for products sold hereunder which are not manufactured or processed by SVT Associates but the manufacturer s warranty for such products if any shall be assigned to the CUSTOMER without recourse to SVT Associates The foregoing warranties are in lieu of and exclude all other warranties not expressly set forth herein whether expressed or implied by law or otherwise including without limitation any warranty of merchantability or fitness for a particular purpose In no event will SVT Associates be liable for any consequential damages IN THE EVENT OF SVT ASSOCIATES LIABLITY WHETHER BASED ON CONTRACT TORT INCLUDING BUT NOT LIMITED TO NEGLIGENCE AND STRICT LIABLITY OR OTHERWISE THE CUSTOMER S SOLE AND EXCLUSIVE REMEDY WILL BE LIMITED SVT ASSOCIATES HAS THE FOLLOWING OPTIONS TO REPAIR OR REPLACEMENT F 0 B SVT ASSOCIATES MANUFACTURING PLANT BY THE COMPANY OF ANY NON CONFORMING ITEM FOR WHICH CLAIM IS MADE BY THE CUSTOMER OR TO REPAYMENT OF THE PORTION OF THE PURCHASE PRICE PAID BY THE CUSTOMER ATTRIBUTABLE TO THE NON CONFORMING ITEM SVT ASSOCIATES WILL NOT BE LIABLE FOR ANY OTHER DAMAGES WHETHER DIRECT INCIDENTAL CONSEQUENTIAL OR OTHERWISE Return Policy Any request by the CUSTOMER for return of standard products other than for warranty claims under warranty hereof for all or any part of purchase order accepted by SVT Associat
54. flectometer measuring a diffusing scattering surface or preferable tilt the substrate slightly so the reflected image of the LED is no longer visible in the video image Another option is to cover the LED s so they cannot be seen in the video monitor This case represents a baseline measurement for which stray LED light is accounted in the calibration The substrate is then restored to its normal tilt position the LED reflection is visible in the center of the video image or the LED s are uncovered You can calibrate the reflectance under this condition because the substrate reflectance is assumed to be known such as for a bare semiconductor wafer Reflectance Calibration Go to Configuration to Reflectance Calibration Reflectance Calibration Data Acquisition Setup Wobble Filter Debug o The Reflectance Calibration window will appear SVT Associates Acculemp File Engine Temperature Reflectometer Configuration Help Reflect 951 30 Reflect 485 00 Signal Reflect Signal Reflect Low 0 00 gt Low 0 00 High 1000 00 High 1000 00 Current Reflect 951 30 nm Current Reflect 485 00 nm 5 30 7 28 MINIMIZE the signals by Channel Wavelengths aligning optical head Pyrometer Channel 1 950 nm Pa Vo Low fl D gt Pyrometer Channel 2 850 nm Get Current Data set gt gt Reflectometer Channel 1 951 3 nm Reflectometer Channel 2 485 nm Save Calibration AEN Communication Initialized 0 LED OFF Logging OFF Figure 28
55. he pyrometry measurement and the emissivity measurement may no longer be correlated since they may be measured at different places on the substrate and hence difference thicknesses If that is the case then the temperature compensation may be compromised and a temperature error may result Substrate rotation or other means of ensuring film uniformity is strongly recommended SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 17 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION Optical Head Alignment The optical head must be positioned so that the LED illuminator and the objective lens on the front of the instrument have a clear and unobstructed view of the substrate under measurement In addition the optical head must be oriented perpendicular to the substrate so that the reflected light from the illuminator is directed back into the objective lens If this alignment cannot be achieved then the reflectance measurement is not possible and the pyrometry performance is compromised Alignment of the optical head using the In Situ 4000 internal light source With the optical head power on start the software application and turn on the LED illuminator Point the optical head so you can
56. ions can be analyzed in real time to provide both film thickness and film index of refraction The In Situ 4000 has powerful analysis algorithms which can provide accurate growth rate thickness and index information This valuable information can even be fed back to the growth system controller to achieve layer thickness precision improvements over traditional open loop timed deposition control The best growth rate and index of refraction measurements are obtained with films of at least 4 4 in thickness where is the reflectometer measurement wavelength i e 950 nm or 470 nm See Growth Rate Fitter Chapter r AYN MART TTI Y ro T a B GaN Growth AlGaN Growth a 0 Ooo oo T ee 0 2000 _ 4000 6000 Time s Figure 5 Growth Rate Measurement during GaN AlGaN Growth using Two Wavelengths 950 nm and 470 nm Reflectance 2 The specular reflectance of a thin film may change with deposition of the film due to multiple layer interference if the film has an index of refraction that is different from the underlying material If the index of refraction of the depositing film is known at elevated temperature then the film thickness and growth rate may be calculated from the periodic undulations in specular reflectance with time Emissivity Compensated Pyrometry The problem of unknown or shifting emissivity is solved using information from the accompanying reflectometer system Under the conditions o
57. is not affected by material properties of the grown layer However the signal for band gap thermometry is attenuated by materials having smaller bandgap energy This degradation depends on layer thickness lt 1 micron but deteriorates measurement performance over time Once an opaque layer has been deposited lt 100 nm pyrometry can in such case take over for uninterrupted temperature monitoring and calibration of the pyrometer This technique is superior to eutectic melting point calibration For materials with higher band gap both techniques can be used aa S 9 amp ie D O 400 v zZ Q a Pyrometer amp Eutectic Al Si Ag Si Bonded TC 100 200 300 400 500 600 700 800 900 1000 Temperature C Figure 38 Combination of pyrometry and band gap thermometry for GaN temperature monitoring over extended temperature range and for optimum accuracy During heterostructure growth interference oscillations due to multi layers occur see Application note 1401 Emissivity corrected pyrometry accounts for these changes and automatically corrects the temperature readings However bandgap thermometry is affected by these oscillations and accurate determination of the bandgap is affected By using sophisticated derivative analysis this effect can be at least reduced SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone
58. is problem It calculates the approximate rotation rate of the substrate and looks back one rotation period in history to find and return the highest reflectance value observed Thus the reflection can completely leave the field of view for a short time and the reflectance value can be preserved during the interruption To activate the Wobble Filter Go to Configuration to Wobble Filter Help Reflectance Calibration Data Acquisition Setup Wobble Filter Debug o The Wobble Filter Window will open SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 36 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION SVT Associates AccuTemp Fik e Engi Eng ine Temperat 2 Reflectometer Coni figuration Wobble Filter Purpose To minimize the effect of substrate rotation on reflectance signals C Wobble Filter on off Enter Estimated Wobble Period S 10 BED 200 0 j 1 1 0 0 10 20 30 40 50 6 0 70 8 0 taps 11 0 12 0 13 0 14 0 15 0 16 0 17 0 18 0 19 0 Communication Iniiakzed o LED OFF Logging OFF Figure 33 Wobble Filter Window Enter an estimated value for the filter keeping in mind that the response time of the reflectometer is slow
59. l Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 18 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION SS n Software Software Installation The software is installed under Windows XP or Windows 7 operating system by executing the program Setup exe on the supplied DVD Follow the directions given by the installation program The DVD provides calibration information please use this calibration information when prompted by the installation program At this point the software installation has the factory calibration values installed on the computer hard disk and will remember these values each time the RoboMBE program is executed Note This procedure to load the factory calibration values must be performed after each installation of the RoboMBE program Note The first time the application is run the serial RS232 communication port or COM Port used by the computer must be assigned and the communication values specified The correct values to use are Data Rate 9600 bps Parity None See Data Acquisition Setup Stop Bits 1 Menus Below is an overview of the software menus with a short description SVT Associates Acculemp Engine Temperature Reflectometer Engine Windows Temperature Window Reflectometer Window Gain Files Data Acquisition Setup Pyrometer Look Up Table Wobble Filter Debu g Exit ea Figure 17 File Menu Log File turn file logging on or off Page
60. ng Standard pyrometry computes temperature from the intensity of emitted radiation If the viewport window through which the pyrometer measures the radiation becomes coated over time the pyrometer temperature calibration will drift accordingly This problem is addressed in the In Situ 4000 through the use of two color or ratio pyrometry which measures optical radiation at two wavelengths and takes the ratio of the measured intensities If the film coating of the viewport is spectrally neutral then the temperature may still be calculated since these errors affect both channels equally Since many of the viewport coating problems deal with metallic type films e g Ga In As these films attenuate the light equally between the two wavelengths the ratio calculation is still valid If the viewport becomes coated with a dielectric film causing interference effects then the ratio measurement becomes imbalanced and may not be valid Alignment and optical obscuration errors This problem is similar to viewport coating in that there are errors introduced into the collection of radiated intensity by misalignment of the optics to the viewport window or other obscuration problems Pickup of stray light Any hot surface in the chamber can radiate light If that light makes its way into the pyrometer the pyrometer will not be able to distinguish between black body radiation of the substrate itself and that of the stray light Thus the str
61. nt at the user supplied guesses until it determines that there is enough data to allow them to vary If the user has specified that the film n and k be allowed to be fit then once the film has reached sufficient thickness the fitter frees them and allows the algorithm to modify the values If the user has specified either of the parameters as fixed then SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 48 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION SS they will remain fixed throughout the current film deposition The fit status of the scaling factor s is not changed by the adaptive fitting Controlling the Fit The fit algorithm is fairly sensitive to the initial guess provided by the user The reason for this sensitivity is that the fit error surface used to fit the model to the data may contain several local minima Some of these local minima are almost as deep as the true global minimum The In situ 4000 Growth Rate Fitter solves this problem by limiting the parameter space in which the fit algorithm searches The user specifies how far the fit algorithm may deviate from the initial guess in its search for the true minimum All parameters except
62. of the flange mount to hold it in place Make sure both 14 20 screws on the bottom are fastened to hold the optical head on the platform e Make sure the objective lens is approximately centered in the mechanical holder to start See Optical Head Alignment section on page 18 of this manual for detailed information 7620 Executive Drive Eden Prairie MN 55344 3677 USA Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com In Situ Process Monitor Version 2 0 4 13 n Figure 12 PROPRIETARY INFORMATION Figure 10 Figure 11 SAAT SVT Associates Inc SVT Associates Proprietary Information 2013 SVT Associates Inc All Rights Reserved Page 14 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION SS Electrical Connections The In Situ 4000 optical head provides a panel of connectors on the rear of the unit for connection of electrical cables The connectors are from left to right video signal sync signal computer interface and power supply See Figure 13 Three cables supplied are needed for normal operation 1 Power supply cable 5034399 2 Computer serial interface cable 5022756 3 Video signal cable 5005834 Video Signal Sync Pulse Computer Interface Power Connector Power Switch Me www svta com Process Monitor 2 SVT Associates lt In Situ4000 Figure 13 Rear view of the optical head showing connector panel Connect one
63. ond duration In addition to the growth rate is calculated using the time between cursors and growth rate from the fit The results of the fitter are stored ina dedicated results file SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 49 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION SS Warranty and Limitations of Remedies SVT Associates warrants that all equipment manufactured by it shall be free from defects in materials and workmanship under normal use and service for a period of twelve 12 months from the date of shipment from SVT Associates manufacturing facility This warranty is subject to SVT Associates equipment being installed maintained and operated in accordance with the operating and maintenance instructions accompanying each item manufactured by SVT Associates Warranty shall be void if SVT Associates equipment is modified by the CUSTOMER or used in other than the recommended manner or applications Purchased equipment incorporated into any item supplied by SVT Associates will be covered by said manufacturer s warranty SVT Associates warrants that at the time of delivery any other products processed or manufactured and sold by it hereunder are free of de
64. ounds O Madelung ed Springer Verlag 1991 The data for GaAs is based on ellipsometry measurements by Aspnes et al Phys Rev B 27 p 985 1983 Reflectance of an assortment of substrate materials at normal incidence and at room temperature Substrate 950 nm Reflectance 470 nm Reflectance Silicon 0 326 0 419 Ge 0 419 0 492 GaAs 0 313 0 438 GaSb 0 39 InAs 0 33 0 454 InP 0 305 0 349 InSb 0 41 Sapphire 0 075 0 078 These values are obtained from the Palik database Handbook of Optical Constants of Solids Edward D Palik Academic Press First edition 1985 2nd Edition 1991 and the Landolt Bornstein tables Semiconductors Group IV Elements and III V compounds O Madelung ed Springer Verlag 1991 The data for GaAs is based on ellipsometry measurements by Aspnes et al Phys Rev B 27 p 985 1983 IN SJ iN CO SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 39 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION SS Editing the Ratio LUT The translation from pyrometry intensity ratio to temperature is performed using a look up table LUT A LUT was chosen because many semiconductor substrates are not ideal grey body emitters
65. ransparency Semiconductors by nature are partially transparent for wavelengths below the band gap that is usually in the infrared portion of the spectrum This transparency causes two severe limitations in pyrometric measurements low substrate emissivity and optical interference from other hot elements in the chamber 1 0 Substrate Transparent for NIR wavelength 0 5 0 5 mm GaAs SPECRAL EMISSIVITY 0 5 1 0 1 5 WAVELENGTH microns Figure 7 Substrate Transparency of GaAs requires small spectral detection range and limits Temperature Measurement to 370 C 950 nm The problem of low emissivity and substrate transparency at infrared wavelengths is addressed by careful selection of the pyrometry wavelength The In Situ 4000 performs single wavelength pyrometry at 950 nm which is short enough to ensure that the substrate is opaque and long enough to ensure a measurable optical radiation at growth temperatures Ensuring substrate Opacity is a key element in addressing several of the previously listed difficulties An opaque substrate prevents radiation from a filament heater from being transmitted though to the pyrometer It also prevents other radiation sources in the chamber effusion cells ion gauge filaments etc from scattering their light from the rough back side of the substrate into the pyrometer Since optical absorption and black body radiation are closely coupled substrate Opacity ensures that the emissivity of the substr
66. s temperature relationship is exponential and allows a direct mapping of intensity to temperature An example radiance curve vs temperature at 950 nm is shown in Figure 2 SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 5 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION A n 100000 10000 1000 100 Radiance x10 4 W m 3 st 400 500 600 700 800 900 1000 Temperature C Figure 2 Radiance vs Temperature at 950 nm Real surfaces have emissivity values less than 1 so the pyrometer instrument used to measure a surface temperature must have knowledge of the particular surface emissivity Two color Pyrometry For surfaces where the emissivity is not known or the radiometer cannot be calibrated with absolute values a technique known as ratio or two color pyrometry may be used Here a single optical system is used to measure the radiance at two distinct wavelengths and the ratio of the radiant intensities is calculated Assuming that the emissivity is the same for the two wavelengths i e a
67. s which can allow the measurement to function well even if the substrate tilts strongly during wafer rotation See Wobble Filter Chapter e Reflectometry Reflectance is used in this instrument for two reasons 1 When single or multiple layer films are deposited optical interference will alter the emissivity of the substrate as a function of time and the single color pyrometry will be in error Measurement of specular reflectance at the same wavelength as the single color pyrometry will allow the calculation of emissivity through the relation 1 R which is based on conservation of energy considerations and Kirchhoffs Law Note that this relation is valid only for opaque substrates SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 7 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION Principle of Thin Film Interference 2n2 mA for maximum reflectance 2n2 m A for minimum reflectance n index of refraction k extinction coefficient d layer thickness Figure 4 Reflectometry is obtained in real time during deposition so that films that have differing index of refraction from the substrate produce reflectance oscillations in time These reflectance oscillat
68. side of the screen see Figure 39 The fitter uses a Simplex algorithm to minimize the error function of the model The analytical model used treats any material underneath the currently growing film as a virtual substrate described only by a single complex index of refraction The virtual substrate can be a simple material like the physical substrate itself or it can be a complex combination of thin film layers on a physical substrate In any case the virtual substrate is modeled with a real substrate index of refraction Ngyp and imaginary substrate index of refraction Ksub The model contains the following fit parameters 1 G Growth rate in nm s 2 N Real part of the film s index of refraction 3 k Imaginary part of the film s index of refraction 4 Neup Real part of the effective substrate s index of refraction 5 Keup Imaginary part of the effective substrate s index of refraction 6 s A scaling factor used to compensate for reflectance attenuation by unintended coatings deposited on the vacuum viewport window 7 Load Setup File button Load any setup files that have been saved Save Setup File button Saves current settings to a setup file to be available for loading at a later date 9 Open Log File Growth Fitter Results Opens the log file for the Growth Rate Fitter The fit algorithm always adjusts the G ngyp and Ksub parameters The user can specify whether or not to fit the other three parameters
69. ssociates Inc SVT Associates Proprietary Information 2013 SVT Associates Inc All Rights Reserved Page 13 of 51 Engines for Thin Film Innovation Mounting Using SVT Associates Flange e Locate the In Situ 4000 Flange Mount The mount should be fully assembled 4 20 screws 4 e There are four 14 20 socket head set screws around the circumference of the mount Using a 7 32 Allen wrench back the set screws out until they clear the inner diameter of the mount See Figure 10 The flange mount has an ID tolerance of approximately 015 inches Nothing such as bolt heads or washers may be protruding beyond the flange Use socket head screws if necessary on your flange e Install the mount over the flange with the platform down Tighten all four set screws equally until the mount is firmly attached to the flange e Looking at the mount find the four 8 32 screws that attach the platform to the side gussets Note that the gussets are slotted These slots allow the platform to be moved vertically and also to be tilted fore and aft e The optical head is attached to the platform through two slotted cutouts These slots allow the optical head to be moved left and right and also allow for a rotational adjustment See Figure 11 e Locate the optical head and mount it to the platform using two 14 20 hex head bolts e Mount the IS4K head using provided flange mount to the chamber viewport Use all four setscrews
70. th rate monitoring using its multi wavelength reflectometer This enables precise thickness monitoring rate monitoring and surface roughness analysis Combining emissivity corrected pyrometry and band gap thermometry in a single instrument provides optimum performance for temperature monitoring during heterostructure growth The AccuTemp process monitor provides dedicated hardware an easy to use software interface and ready to use growth recipes Addition of its spectral reflectometer enables superior process monitoring and control PROPRIETARY INFORMATION SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 46 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION SS nn Growth Rate Fitter The Growth Rate Fitter instrument utilizes data from the reflectometer instrument When a film is deposited on a substrate of differing index of refraction the optical reflectance generally oscillates in time due to optical interference effects see page 7 Reflectance The period of the oscillation is directly dependent on the growth rate of the film and the film refractive index The amplitude phase and damping characteristics of the reflectance are dependent on the film s complex index o
71. the instrument is viewing the substrate If the optical head is separated from the vacuum viewport window by more than 100 mm there will be a reflection from that window back into the reflectometer This glare can be accommodated in the reflectance calibration however the glare signal is often larger than the reflectance from the substrate under measurement and has the effect of significantly reducing the signal quality i e more noise and making the instrument more sensitive to misalignment errors and mechanical motion Use of the optical head with less than 100 mm of distance to the viewport is highly recommended Use With Small Viewports The optical head is designed to view through vacuum viewports with at least a 33 mm diameter window which is found for example on a standard 2 inch Conflat Pyrex viewport flange Smaller viewport windows are not recommended because either the outgoing LED light or the returning reflected light or the black body radiated light will be obstructed by the window frame and the measurement results may be incorrect Contact SVT Associates for further information on using smaller viewports Use With Transparent Substrates The In Situ 4000 is designed for use with substrates that are optically opaque at 470 850 and 950 nm Care must be exercised when attempting to use the instrument with transparent or partially transparent semiconductor substrates Substrate transparency causes the following problems 1 The r
72. tion Page 40 SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 26 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION Engine Menu Operation of the Engine Instrument To open the Engine Window Go to Engine to Engine Window ay Temperature Engine Window o A separate window will appear o This window acts as the main interface to collect data and operate the hardware Engine Window KBS 950nm Pyrometer T am Pe A agint eee Plot OFF ON Plot OFF ON Plot OFF ON Plot OFF ON Pyrometery Gain Reflectance Gain Reflectance Gain 10 N Ea Increase E oa i 400 5 06 00 00 PM Figure 24 Engine Window 1 Pyrometery Gain these fields allow manual gain adjustment of the signal channels See Page 20 Reflectance Gain Buttons To start data collection from the optical head click on the Power toggle switch Turn it to the ON position The Status Bar shows the status of communication 4 Turn on the LED illuminators on the optical head by clicking the LED switch The Status Bar shows the status of the LEDs ON OFF 5 The Debug Normal switch provides diagnostic information on the internal operation of the optical head When the
73. tion values for electronic and optical gain will be transferred from the supplied DVD to the computer hard disk but will not be used by the program until instructed to do so by the user There are 5 files to be loaded by the user and once they have been loaded they are automatically saved by the program and need not be reloaded again on that computer To reset the hardware amplifier gain and offset values back to factory defaults follow the instructions below To open the gain files control screen Go to File to Gain Files eg Engine Temperature Ref Gairm Files Pyrometer Look Up Table Exit o The Gain Files window will appear SVT Associates Acc culenp Pyrometer C2 850 nm io ens Oe Mie 3 TE N 5 eal tooo E C aaa mo a Support p850_4012 gnc C CodelLabViewlIS4K amp Grawth LY Lv See a 4012 gnc Reflect C1 950 nm Reflect C2 470 nm ee a Sica on ee Ge igs Sy ore pe a Peet 1000 se i ooo 929 433 Eao p cod abenitsKB Groh LV Wy i 3 CA CodetLabviewiIs4K amp Growth Lv a 4 i Supportir950_4012 gnc q Supportir470_4012 gnc Automatic Gain Control 5 Muse Automatic Gain Control Communication Initialized o LED OFF LoggngOFF a Ria es amp Figure 22 Gain Files Window SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952
74. uration The actual wavelengths used for computation are 950 nm 850 nm 650 nm and 470 nm Refer to your In Situ 4000 calibration sheet for values specific to your setup Save the values after entering for future use Data Acquisition Setup Go to Configuration to Data Acquisition Setup Reflectance Calibration Data Acquisition Setup Wobble Filter Debug o The Data Acquisition Setup window will appear SVT Associates Acculemp File Engine Temperature Reflectometer Configu Data Acquistion Setup Geometry Factor Averaging 1 Method of temperature Reference User defined Temperature Scan Timers 250 A Com Port Ji User Defined Reference Temperature C 0 Comm Delay Sec t 0 050 Calculated Geometry Factor Sateen Gain Blank Delay 2 000 calculate i 2 100E 5 Set Geometry Factor 7 983E 7 Fixed Geometry Factor C Current Emissivity 10 998 Set Emissivity 0 613 Fixed Emissivity C ae Communication Initialized LED OFF Logging OFF n E Figure 30 Data Acquisition Setup Window 1 Averaging Sets the number of data points to be averaged to minimize noise in graphs typically values from 1 4 are used 2 Scan Time Sets the S232 port numbers that will be used to communicate with the In Situ 4000 SAVA T SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934
75. ustment capability for precise pointing of the instrument Specular Geometry Receiving Head Remote Illuminator AccuTemp Receiving Head Normal Incidence Geomerty Figure 9 Geometry 7620 Executive Drive Eden Prairie MN 55344 3677 USA Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com In Situ Process Monitor Version 2 0 4 13 The optical head should be mounted within 4 inches of the vacuum viewport window for best results Mounting the instrument close to the window reduces the LED illuminator s light from being reflected back directly into the instrument The vacuum viewport flanges compatible with this instrument are 2 75 Conflat Flange or larger Ensure that neither the LED illuminators on the front of the optical head nor the objective lens are blocked from viewing the substrate The instrument is designed to view the substrate from a normal or specular incidence so that the light from the illuminator is specularly reflected back toward the instrument If this geometry cannot be achieved then the reflectometry portion of the instrument will not produce useful information and the pyrometry performance will be limited by no longer allowing emissivity measurement If the user requires a non normal incidence a remote illuminator may be purchased which will provide a specular reflection of the LED light into the optical head SAAT SVT A
76. when multiple layer interference occurs because the In Situ 4000 has the ability to measure the emissivity at the same wavelength as the single channel pyrometry The Temperature instrument has a dialog box that allows you to use the ratio temperature method to calibrate the single channel 950 nm pyrometer when it is valid to do so Go to Configuration to Data Acquisition Setup Configuration Help Reflectance Calibration Data Acquisition Setup Wobble Filter Debug o The Data Acquisition Setup window will appear SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 33 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION SVT Associates Acculemp x mar aA E H ere ii JratIgI nel ture Reflectometer Configuration Help Method of temperature Reference Two channa Terperature Scan Time ms 250 ESD Com Port Hfi User Defined Reference Temperature C 0 Comm Delay Sec 0 050 Calculated Geometry Factor Gain Blank Delay 2 000 cantare 100 ro 1 Set Geometry Factor 7 7 Fixed Geometry Factor C Fixed Emissivity amp Geome Current Ernissivity 0 998 Set Emissivity 0 613 Fixed Emissivity C
77. when you are done No data is lost while AutoScale is off the screen is just not updated during that time By clicking on the magnifier icon you can Zoom into a selected area top left Zoom Horizontally top middle Zoom vertically top right Zoom back out to original bottom left Figure 19 Zoom Features Zoom in around the cursor location bottom middle Zoom out around cursor location bottom right File Menu Logging Data to Files To open the Data Logging window Go to File to Log Files Gain Files Pyrometer Look Up Table Exit o The Log File window will appear SAAT SVT Associates Inc 7620 Executive Drive Eden Prairie MN 55344 3677 USA SVT Associates Proprietary Information Phone 952 934 2100 Fax 952 934 2737 Email sales svta com www svta com 2013 SVT Associates Inc All Rights Reserved In Situ Process Monitor Version 2 0 4 13 Page 21 of 51 Engines for Thin Film Innovation PROPRIETARY INFORMATION SVT Associates Acculemp Log File Settings Log File Size Click to Log Data f0 bytes Log File Path 10sec Log Interval Indicator of data packages via COM port typically 16 34 I Communication Initialized LEC Figure 20 Log File Window To activate Data Logging click the Click to Log Data button o Anew window will appear asking you to name and select where to save the log file SAAT SVT Associates Inc 7620 Executive Drive Eden Prairi

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