FEI Strata Dual-beam FIB

Transcription

1 FEI Strata Dual-beam FIB Quick start Guide Compiled by Mat t hew Hughes and Tony Chen Page 0

2 Purpose of this guide INTRODUCTION This quick start guide is meant to provide cursory operational knowledge and basic steps to achieve imaging and sample analysis for the FEI Strata. An effort has been made to encapsulate common procedures in a concise format. It cannot replace hands-on training. A great deal of detailed information on FIB systems exists, and is freely available. If the information you seek is not within the guide, or for immediate assistance with procedures, you are encouraged to ask one of the CEMN staff. Page 1

3 CHAMBER ANATOMY CDEM Detector Electron Gun Light Source Ion Gun Electron Detectors Pt GIS Capabilities: Schottkey Field Emission/Ga LMIS Guns Outstanding SEM performance at 5kV o Image resolution is ~2nm Outstanding FIB performance at 30kV o Imaging resolution is ~7nm o Milling resolution is ~15nm o Deposition resolution is ~50nm Computer Control Ease-of-use EDX Elemental Analysis STEM Imaging Flip Stage Autoprobe o Nanomanipulation system Pt Deposition XeF 2 enhanced dielectric etching Omnigrid Holder Slot Sample Stage Flipping stage aluminum frame Page 2

4 Imaging controls SOFTWARE CONTROL PANEL Icon Label Detailed Description, Start/Freeze scans Continuous Scan Speed Full frame imaging Reduce scanning window Image with averaging Start integrating Grab 1E Grab 1I Primary beam - E Primary beam - I Control E-beam Control I-beam Auto focus Auto brightness/contrast Search Mode Ultrahigh Resolution Mode External scanning mode Lens alignment Fast link to annotate AutoSave current image Show a live image of sample for E/I beam Set the rate of rastering for E/I beam Image of sample fills frame Show region of interest in smaller window Live imaging averaged over successive scans Integrate several scans into one frozen image Grab single frame E beam snapshot Grab single frame ion beam snapshot Set E-beam as primary Set Ion beam as primary Automatically focus image Automatically adjust B/C Low resolution E-beam imaging mode High resolution E-beam imaging mode EDX analysis mode Activate lens wobbler for centering lens aperture Add annotations to image Save image to current folder Page 3

5 Pattern controls Icon Label Detailed Description Select pattern(s) Filled box Outline Box Line Regular Cross-section Cleaning Cross-section Circle Polygon Milling Order Selection Select Next pattern Delete selection Start/Stop Patterning Select pattern for adjustment/placement Create a fill-in rectangular pattern Create a rectangular frame pattern Create a line pattern Create a stepped-level pattern (trench) Clean the cross-section slice by slice Create a filled-in circular pattern Create a filled-in polygon pattern Choose order of the patterns to be created Skip current pattern and start next pattern in series. Selects. Remove selected pattern Initiate or stop patterning Pages Icon Page name Description Electron Startup page Ion Startup page Electron Adjustments page Ion Adjustments page Work page Image Processing page E-beam control page Ion beam control page E-beam alignment page do not use Ion beam alignment page do not use Patterning edit, stage and GIS control Contains lookup tables and filters Page 4

6 OMNIGRID MOUNTING (ONLY FOR TEM SAMPLE PREPARATION) 1. On the workbench on the left side of the FIB room, there are a set of tweezers, a package of copper Omnigrids, aluminum Omnigrid holder, and a black Omnigrid mounting platform. 2. Wear gloves to minimize contamination of the FIB chamber and reduce pump down time. 3. If not already there, the Omnigrid holder will need to be placed on the Omnigrid mounting platform. a. Place the Omnigrid holder on the mounting platform so that one of the middle Omnigrid slots sits over the pressure pin of the platform. The Omnigrid holder should fall snugly into position. b. Slide the pin vice up so that the tip sits over where the pressure pin will be. c. Tighten the screw by turning clockwise until finger tight. This releases the pressure bar to allow grids to slide into the slot. 4. Open the Omnigrid box. a. Pick up an Omnigrid so that the hole is on the right side. Page 5

7 b. Slide the Omnigrid into the slot under the clamper on the mounting platform and keep the hole of the Omnigrid on the right side (as shown in the figure below). c. Position the grid with the hole ½-covered by the small clamper (as shown below). Posts stick out. Level with clamper clamper ½ of O under clamper 5. Close the Omnigrid box. 6. Untighten the screw and slide the pin vice down. 7. It is now safe to remove the Omnigrid holder from the mounting platform. *When handling the Omnigrid holder, take care not to touch the omnigrid. Page 6

8 SAMPLE LOADING 1. Sign on to the machine in FOM at 2. Please make sure the EDX detector has been retracted before start your session. If NOT, seek CEMN staff assistance. Retracted Inserted 3. Place the specimen on a 12mm or 24mm Al FEI SEM standard stub with double side carbon or copper tape. The specimen should be less than 1 x 1 in X and Y and 5mm in thickness. If the specimen thickness is over 5mm, please seek CEMN staff assistance. 4. Under Electron or Ion Startup page, select Vent Chamber. This prompts a message Venting. Are you sure? a. Go to the mechanical room next to the FIB room (room 15A). b. Turn the nitrogen tank main valve counterclockwise to release the gas. c. Return to the computer and select yes. Wait for about 5 minutes while the chamber is brought up to atmosphere. d. When the specimen chamber reaches atmosphere pressure, open the specimen chamber door gently. 5. With the chamber open, place the Al stub pin into the pin hole of the stage. 6. Make sure the specimen surface is lower than the surface of the flipping stage Al frame (Warning: failure in doing this step may cause damage to the polepieces of the SEM column). Pick up the long hex wrench and insert it into the outer hole on the stage. If this hole is not visible at first, use the rotation knob on the front of the drawer to rotate it into position. It should be facing to the right side of the chamber. Page 7

9 7. If you need to prepare a TEM sample, insert the Omnigrid holder with one or more preloaded Omnigrids at this time. a. Insert the Omnigrid holder into the long channel to the left of the stage so that the restraining bar on the Omnigrid holder faces the sample stage. b. The Omnigrid holder must be seated securely. 8. Slide the chamber door back in gently. There is no need to push hard on it. 9. On the FIB computer, select Pump from the Electron or Ion Startup page. a. Push the chamber door with finger strength. The rough pump starts pumping and makes big noise. The noise should start fading. If not, seek the assistance of CEMN staff. b. Go to the mechanical room and turn the gas main valve off. 10. Watch the vacuum readings on the bottom right of the FIB screen. Once the chamber vacuum drops to ~5e-5 mbar, the microscope is ready for next step. Page 8

10 E-/I-BEAM ALIGNMENT 1. Select desired E-beam voltage and turn on E-beam by clicking HV button a. If the message set Z=FWD? pops up, cancel it. 2. Set I-beam to 50pA and turn on I-beam by clicking HV button. 3. Set primary to E-beam and initiate live imaging. 4. Under the Work page, check that scanning rotation is set to Adjust course focus until surface features are resolved. 6. Pick a feature near the surface which has good contrast and center the image by double-clicking this feature. *A corner or rounded feature works well. For polished samples, dust particles on the surface will suffice. 7. Increase magnification in steps, using course and fine focus knobs up to ~10kx. 8. At ~10kx, follow the stigmation correction procedure. 9. Reduce magnification to one suitable for navigating across the sample. 10. Find the feature of interest by moving the stage with the joystick, or doubleclicking the active image until the feature of interest appears. 11. Select the Stage menu at the top of the screen and either Align X or Align Y. 12. Select two points near the feature of interest, the stage will be aligned to these points respective to the selection of Align X or Align Y. *It may be necessary to repeat this step for small angle rotations. *This step may be made easier by activating the crosshairs under the tools menu. 13. From the Work page, set Z = FWD. Then set FWD = 5mm. This is to link the Working Distance to the Z height. Whenever you see the difference between WD on the E-beam and Z on the Work page, click Z=FWD. (* this cannot be done in ion beam imaging mode). 14. At a magnification of 1~2k, set E-beam imaging in live mode. 15. Double click and center the identifiable feature in the screen. 16. On the Work page, change the tilt to 52 and press ENTER. Page 9

11 a. The image will shift, and will be more pronounced at higher magnifications. You may need lower the magnification to keep the feature visible. b. Watch the direction in which the identifiable feature moves. c. Do NOT double-click the screen to move the identifiable feature back to the center. 17. Mechanically adjust Z to center the feature to the screen. *There are a couple of options for centering the identifiable feature. a. Joystick: Hold the top right button down and move the joystick in the direction opposite that which the identifiable feature moved till this feature in close to the center of the screen. This will slightly raise or lower the stage to the eucentric height of the specimen. b. Software: refer to the scroll bar in the stage section of the Work page (underneath FWD). i. Clicking on the left or right arrows will raise or lower the stage until the identifiable feature close to the center of the screen. 18. To check that the stage is at the correct height, you may tilt between 0 and 52 and notice that the identifiable feature shift is minimized in the image. 19. Keep E-beam imaging at a magnification of 2k~10k. 20. While at 52 tilt, under the Stage menu, select Zero Beam Shift to reset E- beam image shift. 21. Center the identifiable feature. 22. Under the I-Mag menu, check that Mags Coupled is selected. 23. Select Ion beam as the primary beam by clicking, and make sure that scanning rotation is set to Click Auto B/C of ion beam image (*The detector should be ETD or CDI, NOT any TLD detector) 25. While at 52 tilt, under the Stage menu, select Zero Beam Shift to reset ion beam image shift. 26. Using the X-shift and Y-shift knobs will move this image so that the feature locations match that of the E-beam. This is called correlating the beams. 27. Switch primary beams back and forth until the beams are correlated to your desired precision. 28. At this point, you may initiate deposition or removal processes. Joystick Page 10

12 1. Platinum bar BASIC LAMELLA PROCESS a. Set I-beam current to 100 or 300pA. b. Insert platinum GIS or crucible. c. Click Grab 1I. d. Select the Filled Box pattern, and draw a pattern which covers your feature of interest. e. Set Y=1um, Z=1um, and set X large enough to cover the feature of interest. *Remember that the larger the sample size, the longer it will take to prepare. f. Set material file to pt_tem (note that the deposition pattern is red). g. Click Grab 1I and initiate deposition. h. Once this has finished, withdraw platinum rod. i. Click Delete Selection, to remove this. 2. Trench cutting a. Set I-beam current to 20,000pA. b. Click Grab 1I. i) You may need to refocus. Try grabbing another 1I, and turn fine focus knob clockwise/counterclockwise while the image is scanned. ii) Otherwise, activate live-imaging to refocus, but remember that this current will erode the surface of your sample. Page 11

13 c. Select Regular Cross-section pattern, then draw a pattern beneath the platinum bar. i) Set X = the same as the platinum bar +2um, Z = twice the depth of the desired feature, Y = 2Z. ii) Click and drag the box to position it a few microns below and symmetric to the Pt bar. The deepest part of the trench will be near the Pt bar. d. Set material to Si (note that the pattern is yellow). e. Click Grab 1I and initiate removal. f. Once this has finished, click Grab 1I. g. Open the controls menu, and under rotation, enter 180. This rotates the trench. h. Position the trench above the Pt bar, similar to the first trench. i. Initiate removal. j. Once this has finished, erase the trench pattern. 3. Thinning a. Set I-beam current to 7,000pA. b. Click Grab 1I and refocus if necessary. c. Select cleaning cross-section and draw a pattern with X=width of the trench, Z=depth of the trench, and drag the border of the box so that it is close to, but not touching the platinum bar. d. Click Grab 1I and initiate thinning. e. Once this is complete, click Grab 1I. f. Click and drag the pattern above the Pt bar, adjust Y to cover remaining material, remembering to leave a gap above the Pt bar. Page 12

14 g. As with the trench, rotate this pattern by 180 h. Click Grab 1I and initiate removal. 4. U-cut a. Tilt the stage back to 0. b. Go to live imaging with the E-beam, focus and center the image on the center of the platinum bar. c. Lower the ion beam current to 3000pA. d. Initiate live imaging with the ion beam. e. Change scan rotation to 180. f. Using the X/Y-shift knobs, center the ion beam on the middle of the sample g. Click Grab 1I. h. Select Filled Box tool and draw a box to the right of the platinum bar from the top of the sample to just above the bottom of the trench. Remember, you want to leave everything under the platinum. i. Draw a new pattern from the bottom of the first box to the left side of the trench so that this box is longer than the platinum strip. j. Now draw a third pattern from the corner of the previous box halfway up the sample. The resulting pattern will resemble a U. k. Click Select Pattern(s) and draw a box around all three patterns. l. Select parallel and make sure that the material file is Si. All patterns should be yellow since this is a removal process. m. Click Grab 1I and initiate removal. n. When thinning has finished, click Grab 1E. Notice that the left side has been removed and a thin dark line appears beneath the sample in the trench floor. Figures showing U-cut pattern from Ion beam and Electron beam. Note the dark line in the trench in the electron beam image indicating a clean cut. Page 13

15 5. Lift-out a. Lower the ion beam current to 50pA. b. Go to live imaging with the ion beam. c. Insert the Omniprobe. d. Insert the platinum rod. e. Using the other (white) mouse, use the Omniprobe software to position the Omniprobe. The two modes of movement are XY and Z. When XY is displayed, clicking the center square will switch to Z-movement controls and vice-versa. i) In live ion beam mode, you will only control the Z and X movement. Z- movement will raise or lower the Omniprobe. X-movement will move the Omniprobe left and right, but the direction of movement will be opposite to the left/right button on the Omniprobe software. ii) In live E-beam mode, you will control only X and Y movement. f. Position the Omniprobe just above the right corner of the sample. g. Pause live imaging and change ion beam current to 100 or 300pA. h. Click Grab 1I. i. Draw a Filled Box which covers some of the sample, the platinum, and the Omniprobe. Make Z=1um. j. Select pt_tem as the material. The box will turn red. k. Click Grab 1I and initiate deposition. l. When deposition has finished, erase the box and click Grab 1I. m. Change material file to Si n. Draw a Filled box over the remaining bulk to the left of the platinum bar o. Click Grab 1I and initiate removal. p. Once removal has finished, click Grab 1I to verify that the sample is free from the bulk. q. Go to live imaging. r. Use the Omniprobe software to change Z so that the probe lifts vertically from the trench. s. Once the sample has cleared the trench, change Omniprobe speed to 60 um/s and lift the sample/probe away from the bulk. t. Use the Omniprobe software to position the sample/probe tip to the top right corner of the screen. Page 14

16 u. Pull the platinum rod out. v. Pull the Omniprobe out. 6. Attaching sample to Omnigrid a. Go to E-beam live imaging. b. Navigate to the aluminum Omnigrid holder. It will be above the stage. c. Find the leg of the Omnigrid to which you want to attach your sample. d. By twisting the joystick clockwise or anti-clockwise, the Omnigrid holder tilts up and down. Twist until the leg of the Omnigrid is flush with the Omnigrid holder. e. Increase magnification and center the image on the leftmost corner of the Omnigrid leg. f. Adjust focus so that the top of this leg is well-resolved. g. Enter FWD = 5mm. The Omnigrid holder will shift, and may change angles. h. Repeat use of joystick in step d, then focus and enter FWD = 5mm. You may repeat this process until the image does not shift. i. Select I-beam as primary. j. Use the X-/Y-shift knobs to center the image near the top of the Omnigrid leg, but next to a flat area. This will ensure a good weld of your sample. k. Decrease magnification and insert Omniprobe, then platinum rod. l. Using the Omniprobe software, bring the sample to the center of the image so that it is next to the Omnigrid leg. Aligning top of sample to top of Omnigrid Page 15

17 m. The sample needs to be aligned to the Omnigrid so that the top of the Omnigrid is level with the top of the sample. Switch between live imaging modes to align the sample. n. Using 1um/s on the Omniprobe software, slowly move the sample towards the Omnigrid until it barely touches, or the message sample touch alarm appears. If this message appears, carefully back the sample away. Finally, click Grab 1I. o. Change I-beam current to 300pA, set material file to pt_tem, and click Grab 1I. p. Select and draw a Filled box over the gap between the sample and grid. Use the Select pattern(s) tool to enlarge the left side so that the box covers some of the grid. Do the same thing for your sample, but adjust it so that the box covers half as much of the sample as it does the grid. q. Click Grab 1I and initiate deposition. r. Once deposition has finished, change material file to Si. s. Drag the pattern over to the Omniprobe/sample weld. t. Reduce the size of the pattern to the width of the weld; make sure the box does not cover the sample. u. Click Grab 1I and begin removal. v. Once removal has finished, click Grab 1I to verify the Omniprobe is detached from the sample. You may need to remove more if the weld or sample was very thick. w. Once the probe and sample are detached, use the Omniprobe software to carefully navigate the probe back to the top right corner of the screen. x. Pull the platinum rod out. y. Pull the Omniprobe out. z. You may turn off the platinum heat at this point. Sample welded to Omnigrid (E-beam view). Page 16

18 7. Final Thinning a. Go to E-beam live imaging and lower magnification. b. Tilt the stage to 54. c. Double-click on the screen until the sample is near the center. d. Make sure that the EDX detector is out. If so, switch to UHR mode by clicking the UHR icon. e. Use the course and fine focus knobs to resolve the sample. f. Double-click the screen until the image is centered on the center of the sample. g. Change Ion beam current to 50pA, and go to I-beam live imaging. h. Use the Y-shift knob to center the image on the platinum layer. i. Use the X-shift knob to adjust the image so that the Omnigrid is not displayed. j. Pause live imaging, adjust Ion beam current to 1000pA, and click Grab 1I. k. Select the Cleaning Cross-section tool and draw a pattern over the entire sample (below the platinum layer). Set Z = ¾ the depth of the trench made earlier. i) Leave some material on the left, as this will keep the strong connection to the grid weld l. Select Edit at the top of the utility knife frame. Change rotation to 180. m. In the following steps, you will need to pay attention to the removal process. Click Grab 1I and begin removal. Watch the beam indicator line as it steps through the process. When this indicator line moves a bit into the platinum layer, pause removal, and rotate the pattern back to 0. n. Click Grab 1I, reposition the pattern if needed, and resume removal. During this process, you may occasionally click Grab 1I to check the progress. o. Let this process go until about 1 micron of sample (in the Y dimension) remains. Stop removal and delete the pattern. p. Change I-beam current to 500pA and go to live imaging. Quickly bring the sample into focus, and then use the X-shift knob to move the grid off-screen. Click Grab 1I. q. Draw a new pattern over the sample. r. Click Grab 1I and initiate removal. Remove ¼ of the sample from the bottom and stop milling. s. Rotate the pattern by 180. Click Grab 1I and initiate removal. Let removal continue until the platinum layer becomes very thin. Stop removal and delete the pattern. Page 17

19 t. Switch the primary beam to E-beam and go to live imaging. Adjust focus and note the thickness of the platinum layer. In the remainder of this process, milling will continue until the platinum layer in this view is almost gone. u. Change Ion beam current to 100pA and go to live imaging. Adjust focus and use the shift knobs to position the sample as in the last two milling processes. v. Click Grab 1I and draw a box over the remaining sample. w. Click Grab 1I and initiate removal. Let this continue until the indicator line moves into the platinum. Stop removal and click Grab 1I. Sometimes the sample will drift at this current, drag the pattern back over the sample if needed. x. Rotate the pattern by 180. Click Grab 1I and initiate removal. y. Watch the pattern status pop-up window. z. Count ten line patterns and click Grab 1I. If the sample has drifted, click the next button to advance the pattern by one line or stop removal and reposition the pattern. aa. After three counts of ten, click Grab 1E to check the platinum layer thickness. It will most likely be thinnest near the Omnigrid. Once this layer becomes very thin, delete the pattern, tilt the stage back to 0, and switch out of UHR mode by clicking the SHR mode button. Thinned sample (I-beam view) Thinned sample (E-beam view) Page 18

20 SAMPLE UNLOADING 1. Turn off E-beam and I-beam HV 2. Under Electron or Ion Startup page, select evacuate. This prompts a message Are you sure you wish to evacuate? a. Go to the mechanical closet (room 15A). b. Turn the nitrogen tank valve counterclockwise to release the gas. c. Return to the computer and select yes. Wait for about 5 minutes while the chamber is brought up to atmosphere. d. When chamber pressure matches atmosphere, the drawer will slide out easily. 3. With gloves on, open the drawer and take out the aluminum Omnigrid holder and set it safely to the side. 4. Use the long hex wrench to loosen the sample stub. 5. Either by using rounded tweezers, or with gloved hands, remove the stub from the stage s central hole. 6. Slide the drawer back in. There is no need to push hard on it. 7. On the FIB computer, select Pump from the E-beam of I-beam Patterning page. a. This begins pumping down to operating vacuum. b. Return to the closet behind the FIB (room ) and turn the gas off. 8. Sign out of the machine in FOM 9. Return the aluminum Omnigrid holder to the mount. 10.Grab one of the small, white, plastic cuvettes (used to store lamellas) 11.Carefully follow the reverse procedure used to load the grid. 12.Use tweezers to remove the grid and drop it into the cuvette, capping the cuvette when finished. a. Make sure the grid is not stuck to the side near the top of the cuvette. If the lid comes down, it could impact the grid and destroy the lamella. b. Ideally, the grid should be lying flat on the bottom of the cuvette before it is capped. Page 19