LEO SEM SOP Page 1 of 9 Revision 1.4 LEO 440 SEM SOP. Leica Leo Stereoscan 440i

Transcription

1 LEO SEM SOP Page 1 of 9 LEO 440 SEM SOP Gun (Filament) Column Manual Valves Chamber Window Chamber Stage Movement Leica Leo Stereoscan 440i 1. Scope 1.1 This document provides the procedure for operating the LEO 440 SEM. 2. Table of Contents 1. Scope Table of Contents Equipment and/or Materials Safety Load Samples Turn Beam On Navigate Sample Mag, Focus, Brightness, and Contrast Noise Reduction and Saving Unload Samples General Instrument Settings Restarting the System Restarting the Column Vacuum New Filament Conditioning Lab Staff Only Aligning a New Filament Lab Staff Only Equipment and/or Materials 3.1 SEM 3.2 Samples to be imaged

2 LEO SEM SOP Page 2 of 9 4. Safety 4.1 Follow all Nanofab safety procedures. 5. Load Samples 5.1 Open the Vacuum Status window, which can be found under the Stage/Vac menu. Make sure the Gun Chamber valve and Column Chamber valve are both closed. Gun Chamber valve and Column Chamber valve in closed positions 5.2 Open the Specimen Change window, which can be found under the Stage/Vac menu. If tool interlocks have been satisfied, the Vent button will be available. Press it to stop the turbo and vent the chamber. 5.3 Before opening the chamber, check through the chamber window to ensure previously loaded samples will not collide with anything. Undo the chamber door latch and open the chamber door slowly while looking through the window for safety. 5.4 Remove mounting stubs and replace conductive adhesive if necessary. Stick samples to the conductive pads and secure so that samples will not move during tilting/rotating. 5.5 Close the chamber door slowly, again looking through the chamber window to ensure newly loaded samples do not come in contact with anything in the chamber. Close the door latch and press Pump from the Specimen Change window to start the turbo and begin pumping. Replace the chamber window cover. 5.6 Ignore valve position incorrect messages by selecting OK. Clearance between sample and pole piece

3 LEO SEM SOP Page 3 of 9 6. Turn Beam On After System Vacuum is below 8.00e-005 Torr and the Column vacuum has a reading, imaging may begin. Lower vacuum pressures will give a better image and increase filament life. If the Column vacuum reading is greyed out and not refreshing, go to section 13 of this SOP. 6.1 Open the Column Chamber valve. 6.2 Select Standard! from the File dropdown menu. Select Yes to proceed if the Condition incorrect window pops up STANDARD0 Executing will be displayed in the upper right corner of the screen while standard operating conditions are applied, such as accelerating voltage and probe current. Wait until the words STANDARD0 Executing disappear before clicking anything else. 6.3 At this point faint outlines of the sample should be visible. Adjust Focus, Brightness, and Contrast to clarify the image (see section 8 of this SOP). 7. Navigate Sample The stage will be translated, tilted, and rotated to image the desired sample location and orientation. USE CAUTION WHEN MOVING SAMPLE AND OBSERVE THROUGH CHAMBER WINDOW TO AVOID COLLISIONS! 7.1 Translation is controlled with the Y and X micrometers mounted in the chamber door. The micrometers may be turned: 1) Manually by hand 2) With the keyboard arrow keys after pressing the S key once ( S for stage ) 3) With the Stage:Joystick window found under Stage/Vac > Stage Move.. Y Y X X Shows how micrometers relate to screen movement 7.2 Stage Tilt is controlled by hand using the TILT knob on the chamber door. USE CAUTION WHEN TILTING! 7.3 Stage Rotation is controlled by hand using the ROTATE knob on the chamber door. USE CAUTION WHEN ROTATING! 7.4 Stage height is controlled by the Z micrometer on the front. This should not be adjusted and the stage should remain low to avoid collisions.

4 LEO SEM SOP Page 4 of 9 8. Mag, Focus, Brightness, and Contrast After desired sample position and orientation has been attained, adjust the following 4 parameters to achieve the best possible image Mag Set the magnification by clicking on the mag/focus glass icon and moving the mouse horizontally (left/right) while holding the left mouse button Focus Adjust the focus by clicking on the mag/focus icon and moving the mouse horizontally while holding the center mouse button (10-22 mm) Brightness Adjust the brightness by clicking the brightness/contrast icon and moving the mouse horizontally while holding the left mouse button (~40%) Contrast Adjust the contrast by clicking on the brightness/contrast icon and moving the mouse horizontally while holding the center mouse button (~20%). Mag/focus icon Brightness/ contrast icon For the previous four parameters, it is possible to speed up the process by selecting a reduced raster zone. Reduced size raster zone may be toggled with the monitor buttons. Full Frame Scan speed may be varied with the arrow buttons. Slower Faster 9. Noise Reduction and Saving After the image is as clear as possible using the previous adjustments, turn on noise reduction to produce a final image. 9.1 The Noise Reduction window may be found under Image > Noise Reduction Frame Avg. or Line Avg. may be used for averaging Adjust the corresponding sliders to set the number of scans used in the averaging calculation. 9.2 Slow down the scan speed to improve clarity (~1 min cycle time). Averaging sliders 9.3 Click At end to freeze the image at the end of a scan A blue rectangle will appear in the lower right corner once the frame has been frozen. 9.4 After the image has been frozen, export it to the second computer Check the save location by going to File > User Directory.. If e:\ is displayed in the upper box, the correct drive is selected. Otherwise select [-e-] and press OK Open the TIFF file export [e:\] window under File > Export TIFF.. Select the [-e-] drive for saving

5 LEO SEM SOP Page 5 of Add a Title and image number. Additional export parameters can be found under More.. Title box Appended # (Automatic) File will be saved as NAME When everything has been checked, press OK. Wait until the window closes to proceed Check the image on the second computer to ensure proper brightness, etc. Image exported to C:\users\LeoIN. 9.5 Unfreeze the image, reduce averaging count, and increase scan speed using the Noise Reduction Window. 9.6 Navigate the stage to the next desired sample location. 10. Unload Samples 10.1 Turn off the beam by selecting Beam Off, found under Beam Make sure the Gun Chamber valve and Column Chamber valve are both closed Select Vent from the Specimen Change window, which can be found under Stage/Vac Before opening the chamber, check through the chamber window to ensure previously loaded samples will not collide with anything. Undo the chamber door latch and open the chamber door slowly while looking through the window for safety Remove samples from mounting stage and slowly close the door, checking clearance through the chamber window. Latch door closed Select Pump to leave the chamber under vacuum.

6 LEO SEM SOP Page 6 of General Instrument Settings The Nanofab s SEM is meant for rapid prototype imaging, and not advanced microscopy. Users seeking a more in-depth analysis should refer to the Microscopy Core. Here is a list of settings and how they should be applied. Selecting STANDARD! from the File dropdown will apply the following settings. EHT (M) = kv This is the accelerating voltage used in the column. FIL I(M) = 2.70 A This is the current run through the filament producing the electron beam. I Probe = 150 pa This is the total electron current reaching the specimen surface. Also controlled automatically via Optibeam res mode auto. Collector Bias = 250. V May be varied -250V to +400V. Optibeam Mode Mode Depth Optional Aperture Data Select the second aperture 50μm diameter

7 LEO SEM SOP Page 7 of Restarting the System Software crashes are common, especially if the system is interrupted during a save or while performing a macro such as STANDARD0. If the software is unresponsive, perform the following steps Press the RESET button located on the front of the table Press the ON button The system will start. Logon Name: leo Password: leo Select [-e-] as the Directory for own files. Press OK twice Press OK to any messages that come up. Press RESET then ON to Reboot 12.5 Once the system has finished Start Up if may be necessary to enable the data zone by selecting View > DataZone If the Datazone is undefined: Right click on the image area and select Annotation. Right click again in the image area and Select File > Load > dz.ann > Open from the Annot/meas window. Position the Data zone along the bottom, centered. Select Panels > Data Zone > Install and click on the data zone box to set it as the data zone. Standard Data Zone 12.6 If Panel not found window pops up, select Load Panels under Tools > Service Stage initialization may be required to move the stage electronically. Check through the chamber window to ensure translational clearance. Open the Stage Initialise window found under Stage/Vac > Stage Initialise.. and select Stage init If the system is unable to boot using the RESET and ON buttons, press the red button to kill the turbo and perform a hard reset, followed by RESET and ON.

8 LEO SEM SOP Page 8 of Restarting the Column Vacuum At the top of the SEM near the gun is an ion pump that also functions as a pressure gauge. Chamber pressure must be 5e-6 or lower before the ion pump will turn on. Under normal conditions the ion pump is always running to keep the column under vacuum. If the Column Vacuum reading is greyed out, the column vacuum will need to be restarted Evacuate the chamber and column by selecting Pump from the Specimen Change window. Gun chamber valve should be open Select Column Pumping-> from the Vacuum Status window Select Start column pump from the Column Pumping window Column pump and pressure reading will come on once the chamber pressure is below 5.00e-006 Torr Once there is a Column vacuum reading close the Gun chamber valve and proceed as normal. 14. New Filament Conditioning Lab Staff Only If the filament burns out, it is time to be replaced. This is normal, and filaments last hours. If a hot filament is exposed to air, the filament will oxidize and burn out quicker. This is why the column is kept under vacuum, as well as to reduce pump down time. Always increase filament current slowly when breaking in a new filament Open the Gun Set Up window found under Beam Ensure Filament Type= Tungsten 14.3 Select New Filament Yes. This will restart the filament clock Make sure the Fil I(T) slider is set to 0A. The EHT (T) slider should be at kv Select Beam On! from the Beam dropdown menu Every 2 seconds increase the filament current by 100mA (one click) by clicking on the slider arrow until current is 2A (5-10 minutes of clicking). Next increase current by 100mA every 5 seconds until 2.7A is reached.

9 LEO SEM SOP Page 9 of Aligning a New Filament Lab Staff Only Once a new filament has been conditioned, alignment may be necessary Open the Gun Alignment window found under Beam > Gun Align Select Emission Adjust Gun Shift with Optibeam Mode Depth on. Center the spot. Gun Shift with Optibeam Mode Depth On 15.4 Adjust Gun Tilt with Optibeam Mode Depth off. Center the brightest area. Gun Tilt with Optibeam Mode Depth Off 15.5 Select Normal Produce the best image possible Use Focus Wobble to align the aperture (Mag = kx) Open the Focus wobble window found under Beam > Wobble Set the Amplitude high and check the Fast box Adjust the aperture micrometers until the image in the green box no longer moves. X micrometer corresponds to vertical movement. Y micrometer corresponds to horizontal movement. X mm and Y mm values listed in the Aperture data window are for starting reference only. Actual micrometer readings will be different when aperture is aligned. Aperture Micrometers located on column 15.8 Repeat steps to ensure best image quality. Magnification level for the focus wobble should be kx.