1.1. Log on to the TUMI system (you cannot proceed further until this is done).

Transcription

1 FEI DB235 SEM mode operation Nicholas G. Rudawski (805) Sample loading 1.1. Log on to the TUMI system (you cannot proceed further until this is done) The FIB software (xp) should already be open and running. Login with your username and password (you will receive this after training is completed) On the far upper right corner of the software, enter the key panel by clicking on the icon Under the Vacuum control click Vent to start venting; it will take ~2 min for the chamber to vent. You will know the chamber is vented when the chamber door can be pulled open with little resistance Insert the stub end of the sample puck into the stage and lightly tighten the setscrew. Use the metal dog-ear and adjust the Z control knob on the outside of the door until the top of the sample is just under the bottom edge of the dog-ear Remove the dog-ear from the stage, close the chamber door and click Pump ; be sure to apply light pressure to the door during the initial pump down. 2. Preliminary checks 2.1. In the Confirm holder dialogue box that pops up after starting pumping, select the appropriate holder and select OK. 1

2 2.2. In the menu, go down to Status and check that Vacuum Status reads Vac OK and Chamber Pressure is < 1.0E-4 mbar and stable. 3. Turning on the beam and finding an area of interest 3.1. In the menu under Electron Column, select HV to turn on the E-beam ( HV will turn from gray to yellow) Under Status, check that the E Column HV and E Spotsize are reading the indicated values in Electron Column. For most purposes, HV = 5.0 kv and Spotsize = 3 are usually sufficient. Increasing HV will reduce probe size, but at the expense of a larger excitation volume. Likewise, increasing Spotsize will increase probe current, but at the expense of a larger probe. 2

3 3.3. Along the row of icons below the menu bar, select and to select the E-beam for imaging. The default setting for the instrument is SRH mode, which can be used for the full magnification range, but is best for magnifications < 2.5 k (otherwise UHR mode can be used as described later) Select Detector along the top menu bar and select a detector from the pulldown menu; either SED or TLD-S can be selected. Both are secondary electron detectors, but the corresponding images will look different owing to different detector positions. to start live imaging with the E-beam Use the joystick and move around until you find a general area of interest (alternatively, you can double click on a point in the image and the stage will move to center that point in the image). 4. Adjusting live imaging parameters 4.1. Under Scan along the top menu bar, select Set Continuous Scan In the dialogue box that pops up, several different image resolutions and refresh times may be selected The live image can be averaged to reduce noise. Under Scan along the top menu bar, select Set Average and select the desired number of frames to average. The noise will be reduced with increased averaging, but the refresh response will be slower. 3

4 5. Setting eucentric height 5.1. Use the magnification selector knob on the desktop control panel to increase the magnification to ~1 k Find and center in the image a flat recognizable feature on the sample surface near the area of interest Focus the image using the desktop control panel; then select (stage cannot be tilted unless this is done) Enter the Swiss army knife panel by selecting the icon to the right of the icon In the bottom of the panel, find the stage tilt T and input a value of 5. The image will shift either up or down (probably down) as stage is tilted Use the Z control knob on the chamber door and adjust until the feature is once again centered 5.7. Refocus the image refocus the image using the desktop control Repeat the previous 3 steps inputting T = 10, 20, 35, and Return the stage to T = Increase the magnification to ~10k. 4

5 5.11. Find and center the feature in the image, and focus the image Repeat the tilting/z adjust/focusing sequence again, and return the stage tilt to T = 0 when finished Repeat the same tilting/z adjust/focusing sequence used previously, and return the stage tilt to T = 0 when finished If eucentric height was set correctly, the specimen should be in focus with FWD ~ 5.0 mm. 6. Alignment 6.1. Specimen must be at eucentric height for alignment to work correctly. It will also be easier to perform alignment with stage tilt set to T = Select the lens align icon along the top menu bar (the image should start to go in and out of focus and rotate along the outside) In the following dialogue box that pops up, click and drag on the crosshairs and adjust until the center of rotation is centered in the image (image movement minimized). Select OK when finished Adjust the stigmation controls on the desktop control until the image is as sharp as possible (this is usually most effective at high magnifications and using small, round features). 7. Using UHR mode 7.1. The specimen should be at eucentric height as described previously; the stage tilt should also be set to T = 0 for purposes of alignment. 5

6 Magnification must be > 2.5 k and HV must be 18 kv or UHR mode cannot be activated Select the UHR mode icon 7.4. Under Detector along the top menu bar, select TLD-S or TLD-B from the pull-down menu (detects secondary or backscattered electrons in UHR mode, respectively); the SED detector cannot be used in UHR mode Use the focus knob on the desktop control to focus the image (FWD will be slightly different compared to SRH mode, but still close to 5 mm) Select the lens align icon along the top menu bar (the image should start to go in and out of focus and rotate along the outside) In the following dialogue box that pops up, click and drag on the crosshairs and adjust until the center of rotation is centered in the image (image movement minimized). Select OK when finished Adjust the stigmation controls on the desktop control until the image is as sharp as possible (this is usually most effective at high magnifications and using small, round features). Still image acquisition 8.1. from the top menu bar. Focus (and stigmate, if needed) the image in live mode at a magnification slightly higher than the one at which a still image will be acquired (e.g. 120 k for still image acquisition at 100 k ). 6

7 8.2. Under Scan along the top menu bar, select Set Grab Frame E In the dialogue box that pops up, several different resolution and acquisition times may be selected After choosing a still image acquisition setting, select along the menu bar to acquire a still image. 9. Finishing the session 9.1. If necessary, reset HV = 5.0 kv and Spotsize = 3 under Electron Column. If in UHR mode, return to SRH mode by selecting along the top menu bar; alignments will be lost (particularly the stigmation) when switching back to SRH mode, so realign the SEM in SRH mode as a courtesy to the next user Make sure the stage tilt is set to T = Return to the key panel Select HV under Electron Column to turn off the E-beam voltage. 7

8 9.5. Verify that E-Column HV is at 0.0 kv under Status Select to freeze the live image; (DO NOT continue live imaging with the beam off) Select Vent under the Vacuum control and agree to the dialogue box that pops up asking if you want to proceed with venting Select Stage from the main menu bar and select Initialize Stage from the dropdown menu. Select Ok from the dialogue box that comes up When the chamber is vented, remove your sample, close the chamber door and click Pump under the Vacuum control Log off the xp software and then log off the TUMI system. 8