Running LEO 1450VP SEM
Contents
1. Electron Microscopy Centre Title RUNNING LEO 1450VP SEM Equipment LEO 1450VP SEM Revision 1 0 Effective Date 20 11 2005 Author X Yang Warning please make sure you are aware of the precautions that you must n Before you attempt to operate this equipment for the first time take to ensure your own safety Warning IN AN EMERGENCY PRESS THE RED ILLMUNATED STOP BUTTON Warning The EHT voltages present in this instrument aea vorrace CAN be lethal Working Environment Do not use electrical equipment in e Rain or excessive moisture environment e The presence of flammable or explosive gases The equipment is not designed to be water or splash proof or to be used in area where there are flammable or explosive gases or fumes Running LEO 1450VP SEM Basic Instructions a fe Hee E 9 Logon LEO 1450VP user interface Load your specimen and standards please wear provided powder free gloves only Turn on the filament and set accelerating voltage to desired operating conditions 1f not sure set 20kV The default detector has been set to collect secondary electrons You can now work on obtaining a sharp image using stage position focus stigmators image brightness and contrast Set the working distance to desired value and adjust the spot size Adjust the brightness and contrast if necessary Save the desired image after scanning When done with collecting data turn off the beam and wait for 32. be at a working distance Ej of 19mm to 25mm The Spot Size value can be adjusted from the user interface in the range 1 to 1000 In most cases a value of 333 gives a good video signal without over exposing the sample to electron bombardment Other settings would be as follows Purpose of Viewing Spot Size Value High Resolution 120 to 230 Backscattered electron imaging 380 to 450 X Ray analysis 460 to 500 Charge or beam sensitive samples 160 to 220 The improved resolution performance at low values is achieved because the diameter of the beam on the specimen is reduced A larger beam diameter is acceptable for X ray analysis because of the larger volume of interaction 6 Adjust the brightness and contrast if necessary Set Brightness to 95 and adjust Contrast until the imaging can be viewed Readjust Brightness and Contrast if the image 1s too bright or dark 7 Save the desired image after scanning Before you start saving an image you have to freeze the image first This could be done by left click the Pause button if you want to freeze right away or middle click the button if you wish the image to be frozen at the end of the frame You could save a desired SE image under Menu Bar click on File and Save Image then choose the folder you would like to file to be saved 8 When done with collecting image turn off the beam and wait for 30 min so the filament is cooling down to room temp 9 Remov
3. start from a low Reet magnification such 30x 50x and switch to 1 100 0 um z higher magnification Pl Focuswobble M wobble Fast iweb mplitude 2 04 You could focus the image by selecting focus mg mode and turning the FOCUS BESAS VES knob In this case the working distance WD Mag Focus AutoSat 2utosian physically remains but the electron beam Emission Stigmation Shift Tit focus on different level to match the WD The Bani Skigmation WD value becomes REAL only when the F Opi w Optibearni beam is well focused on specimen Auto Resolution Gesth Made You could also focus by changing the Z position of your sample this is the physical distance between the sample holder and the aE erence pole piece the tapered column that hangs above your sample BE CAREFUL You might inadvertently ram your sample into the final lens Therefore you may want to switch on the infrared camera TV mode so that you can pay attention to how close your sample is from the pole piece I ErediSperture Stigmation While you are still at high magnification with small circular or rectangular features in the image generally 10 KX which is high enough to clearly display astigmatism through focusing will lead from one privileged focus direction Figure la to another Figure 1b if astigmatism exists Once you have made your final focus adjustments with FOCUS FINE to obtain an image quality which lies be
4. 0 min so the filament is cooling down to room temp Remove specimen from chamber close the door before pumping 10 Log off the LEO user interface 11 Remember to fill the log book Running LEO 1450VP SEM Detailed Instructions 1 Logon LEO 1450VP user interface There are two computers on the SEM but only one keyboard and mouse The monitor for the SEM computer is on the left this is computer 1 The monitor for the EDS system is on the right this is computer 2 The red number on the gray box in between the two monitors indicates which computer the monitor and keyboard are working with If the red number is 2 please switch the keyboard and mouse to computer 1 by simply hitting Ctrl Alt 1 Click on the LEO icon on the SEM computer desktop and logon the software interface using the username and password assigned to you 2 Load your specimen please wear provided powder free gloves only The first thing you will want to do is to load your sample Please make sure the filament has been turned off at least 30 minutes so to increase the lifetime the filament Do this by right clicking on the Vac button in the bottom right corner and select Vent button at the popup widow This will vent the sample chamber and allow you to open the sample chamber door It will take approximately 5 minutes to balance the pressure within the sample chamber with atmosphere Never pull the door during the 5 minutes venting period another detector E
5. DS has a fragile and expensive window a sudden pressure increase in the specimen chamber would likely damage the EDS window LB Bighiness 50 0 ME Contrast 50 0 Macro Idle BABE Vac y Fil X EHT gt lt Never reach into the sample chamber without gloves on Always use the sample exchange tool tweezers and special designed screw driver to switch your sample with the one that is already in the chamber Put the sample you just removed into covered box to prevent the dust If you are not familiar with the sample exchange procedure or how the sample stubs fit onto the stage please ask for help WARNING Any bare hand operation during the sample loading unloading may result in loss of privilege of using the system Once your sample is secure on the stage and positioned approximately where you want it close the door latch it and right click the Vac button on the computer then select Pump to begin the pumping process After about 5 minutes the Vac indicator eedi will shows a ready sign At that point the sample chamber is under vacuum and you are ready to begin viewing your sample Itis always a good idea to wait a litter longer until the vacuum reading is approaching 10 torr Stage Manager x xi x Stage Points List tab Stage Points List tab Stage Properties tab Stage Points List tab Stage Properties tab Stage Scanning tab Stage Scanningtab Stage Survey tab Stage Scanningtab Stage Survey tab Stag
6. detectors within the chamber it is always a good practice to move the sample at front end of the stage under the column and rotate the stage to locate your interested one It is important to remember that the specimen must be flat or not tilted for BSD detection Turn on the filament and set accelerating voltage to desired operating conditions if not sure set 20kV Fill lt EXT X Right click on to Fil button and select beam on to turn on the beam At this time you should enter your information and the time on into the SEM logbook Beam damage can be the result of using high voltage or a high probe current thus the accelerating voltage and probe current should both be adjusted together to determine the optimum settings Coating the specimen with conducting film such as gold often helps to dissipate the heat generated by the beam However better results are usually obtained by operating at lower voltages Work on obtaining a sharp image using stage position focus stigmators image brightness and contrast The default detector SE1 has been set to collect secondary electrons You can now work on obtaining a sharp image using stage position focus stigmators image brightness and contrast SEM Control In order to get an image you will have to adjust the focus contrast and brightness It is Detectors Scanning Vacum 1 d f 1 Gun Apertures Stage X Ray always a good practice to
7. e Navigation Tab Stage Navigation Tab Stage Status tab Stage Navigation Tab Stage Status tab f Side on Side on m Side on qy This view shows This view shows This view shows the selected stage the selected stage the selected stage sample holder and is side on to the holder The horizontal line shows the sample height parameter ES r Perpendicular This view shows a perpendicular perpendicular perpendicular view to the holder view to the holder view to the holder The horizontal The horizontal The horizontal beam center line beam center line beam center line is visible when is visible when is visible when Stage Tilt 0 Stage Tilt 0 Stage Tilt 0 Show Fields Safe stage allocation Simply turn the stage to reach next sample Stage Manager sample holder and is side on to the holder The horizontal line 4 shows the sample 7 height parameter m Perpendicular This view shows a Show Fields Unsafe stage allocation sample 4 3 migh hit detectors when moving Stage Manager sample holder and is side on to the holder The horizontal line shows the sample height parameter m Perpendicular This view shows a FT Show Fields along Z direction While waiting for the vacuum to be ready adjust the sample stage and locate your first sample under the center of the column In order not to hit on any
8. e specimen from chamber close the door before pumping 10 Log off the LEO user interface In the Menu Bar click on File and Log Off then OK to log off the LEO operation system You can also log off the system by closing the window Reminder you have to log off the LEO system after finishing your research otherwise the computer log system would mistakenly consider you are still using the machine and therefore extra charge may occur due to extended logon time to the system 11 Remember to fill the log book Reference 1 LEO 1400 Series Scanning Electron Microscopes Operator User Manual LEO Electron Microscopy Ltd Cambridge England 1998 2 LEO 32 Help Manual LEO Electron Microscopy Ltd Cambridge England 1998
9. tween the two images you should adjust the Stigma X and Stigma Y to try to improve the focus slightly one direction at a time Repeat the procedure if necessary You could also use Autostig if noise in the image is low and features are well defined Moving between fine focus and Stigma adjustments at high magnification may provide small but sometimes significant improvements to the quality of your image b Figure 1 Comparison of images under different focusing conditions From LEO32 Help 5 Set the working distance to desired height and spot size SEM Contral The choice of working distance is strongly depended on user s specimen and most time Detectors Scaming Vacum Gun Apertures Stage Hay user might have to make a compromise Here are some the factors suggested to be EHT 0 00 kV considered FFill Opa Beam State Shutdown a 1 As the working distance is decreased the wh hee hse available resolution increases Filament Type Tungsten a 2 If the sample is large it is wise to use a i T Low EY Spacer longer working distance in order to eto avoid being hit on the lens or BSD 3 The retractable BSD occupies a finite Beam Current _80pA space beneath the final lens A safe Spot Size 254 working distance is 10mm to 12mm or El higher Fill Target 3 6004 4 The geometry used for X ray analysis i Ep EDS dictates that the surface to be EHT Target 20 00 kv analyzed should
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