Performing regular Preventive Maintenance on surface analysis systems such as X-ray Photo Electron spectrometers (XPS) and Auger Electron spectrometers (AES) is a very important step in keeping the systems functioning properly and reliably. But performing the necessary steps in the correct PM sequence will make sure that you maximize the use of your time. Below are the PM sequences that I use when performing preventive maintenance on XPS and AES surface analysis systems.
5400/5500/5600 System Maintenance Guide
PM Procedure – OPTICS
- Discuss System performance and issues with system operator prior to service visit.
- Inspect system, note base vacuum. Test TSP filaments.
- Make sure that you have all necessary parts for the maintenance. If you are missing anything, order it before proceeding. For maximum efficiency, you will perform vacuum maintenance first as you can inspect and clean the electronics during the system bake out and cool down.
- Prepare to vent the system by shutting down all filaments and voltages to the ion guns, X-ray sources and neutralizer.
- Turn off the DIGIII and Boostivac. Let the system cool for 10 minutes.
- While the system is cooling, prepare a work area for optics maintenance.
- Vent the system (make sure that the turbo pump(s) are on to prevent oil vapors from back-filling during the vent process). After the system is up to air, turn off the turbo pump(s).
- Remove the X-ray source(s) from the chamber and inspect the filaments, window, football ceramic and anode. Replace parts as needed.
- Remove the ionizer from the Ion gun and inspect the ionizer. Replace if needed.
- Remove the Ion Gauge and inspect the filaments. Replace if needed.
- Replace TSP filaments as needed.
- If the 04-085/090 Neutralizer filament needs to be replaced, remove the neutralizer and replace the filament. It should be replaced every 4 years of normal usage.
- If channel plates or electron multiplier needs to be replaced, remove the 6″ flange on the SCA and replace the multiplier. This typically is replaced every 3 to 5 years depending on usage.
- Inspect the ion gun ionizer and replace if needed.
- Pump down the system.
- Start the ion pumps.
- Prepare the system for bake out – NOTE: Remove the microscope by unscrewing the locking screw. Do not remove the lower portion to make it easier to re-align the microscope after the bake out.
- Once the system reaches at least the mid 10-7 Torr range, then the system can be baked for 12 hours.
PM Procedure – ELECTRONICS
- Make sure the card rack power is off and visually inspect all electronic cards and units.
- Clean all edge connectors with alcohol and q tips (not an eraser).
- Replace as needed any marginal capacitors, resistors or transistors.
- Replace all neon bulbs.
- Replace CM85 bulbs in EMU unit as needed. Note that if the Vacuum Console bulb needs to be replaced that the entire system needs to be shut down first.
- Clean electronic card rack filters.
- Inspect 16-020 or 16-050 heat exchanger for dust on radiator, clean as needed.
System Outgas Procedure
- With the card rack power off and all electronic units off as well (except for the ion pumps, DIGIII and turbo pumps), re-connect all system cables.
- Reconnect the microscope.
- Load the slotted silver sample into the system.
- Turn on the card rack power and the power to the Ion gun control and X-ray source control.
- Load AugerScan software.
- Turn on the ion gun control and outgas the filament slowly to 25mA and 2 to 3kV. Do not sputter the slotted silver sample at this time.
- Out gas the X-ray source filaments and condition the anodes to 16.5kV slowly.
- Lightly sputter the slotted silver sample.
- Find the focal point of the SCA using the slotted silver sample and align the microscope to that point.
- Load a piece of Cu and AU side by side an calibrate the pass energy tracking and then the XPS energy linearity.
- Calibrate Small Spot on Slotted Silver Sample
- Calibrate Au and Cu peak linearity:
- * Pass Energy Tracking
- * Au 84.0
- * Cu 932.67
- Align ion gun to focal point. – Load a piece of TaO5 with an X scribed into it. Put the X at the focal point of the microscope and then burn a hole into the TaO5 with no raster. Adjust the ion source as needed to center the sputter crater in the middle of the X.
Refer to the counts/resolution Specifications for the specific system type that you are testing. In general, if the resolution spec (less than .8eV FWHM on clean silver) can be met then the system will be performing properly in all pass energies.
595, 600 and 660 PM Sequence
Following the sequence listed below will maximize the use of your time when calibrating and documenting system performance during a PM or installation of a 595, 600 or 660 scanning Auger system.
Perform optics checks (CMA filament, SED and CMA electron multipliers, TSP filaments, Ion gun ionizer and ion gauge filaments) and replace parts as needed. Bake out system.
Perform electronics inspection. Clean air filters if applicable.
- Load a sample with SiO2 and Cu side by side.
- Adjust the elastic peak on the SiO2 with the sample at 60 degrees with respect to the analyzer. That is 30 degrees on a 600 or 660 specimen stage.
- Align the ion gun to the center of the SiO2.
- Move to a fresh spot of SiO2 and lightly sputter the sample with a raster of 2 X 2.
- Change the sample angle to perpendicular to the analyzer. That is Zero degrees on a 600 or 660 specimen stage.
- Select point mode and acquire an elastic peak.
- Adjust the Z axis for maximum counts.
- Adjust the collector housing (600 or 660 only) for max counts and best peak shape. This will be slightly non-Gaussian.
- Readjust the Z axis for max counts. This does not need to be exactly 3kV.
- Check the analyzer resolution for 18 eV between the differentiated and balanced peaks of the elastic peak at 3kV (or 12eV at 2kV on a 595).
- Adjust the resolution knob if needed to obtain 18eV differentiated and set the resolution knob to indicate .6%.
- Recheck the Z position and collector housing adjustment to ensure that the sample is at maximum counts and 18ev differentiated.
- Move to the copper sample, set the tilt to 60 degrees with respect to the analyzer and adjust the elastic peak for max counts with the scanning set to 10kX magnification (to eliminate topography effects).
- Sputter clean the copper until there is no carbon present.
- Re-check the elastic peak to ensure it is at maximum counts and 18eV when differentiated.
- Check the AES energy position of the 914 Cu peak (917 differentiated). Note: The earlier handbooks indicate 920 differentiated, the newer handbooks indicate 922 eV differentiated, and the correct position is 917 differentiated for the 595, 600 and 660 analyzers due to the magnetic lenses. However, you can set it to whatever the system operator prefers. We recommend 917eV.
- If the Cu peak does not come in at 917eV, then adjust the AES scale factor until the peak comes it at 917eV differentiated (or what the system operator prefers).
- Acquire another elastic peak but DO NOT MOVE THE SAMPLE. If the peak does not come in at 3kV (2kV for a 595), then adjust R108 in the 20-610 HV supply until the elastic peak is at 3kV.
- Document result (3kV elastic peak at .6% resolution).
- Acquire a survey from 30 to 1030 Ev and Document result (AES energy calibration). Annotate the Scale Factor and Cu low and high energy positions.
- Verify that low energy copper peak and high energy copper peak are a ratio of approximately 1:1.
- Set beam voltage to 10kV and with the objective aperture set to the largest; adjust the COND and filament housing position for maximum target current.
- Adjust emission current for maximum target current. Document result (max beam current). Specification is greater than 10uA at 10kV.
- Set the aperture to the number 2 aperture and the COND to about 45. Set the beam current to 10nA. Refocus the image, set back to 10kX magnification.
- Acquire a survey from 900 to 960 eV, 1 eV per step, 50mS per point, and 5 sweeps.
- Calculate the signal to noise (P-B/ B). Document result (10nA S: N), specification is greater than 250:1, near 300 is typical.
- Set the beam current to 1nA (COND to about 50) and acquire the survey again.
- Calculate the signal to noise (P-B/ B). Document result (1nA S: N), specification is greater than 80:1, near 100 is typical.
- Move back to the SiO2 and reset the beam voltage to 3kv, COND to about 40.
- Acquire an elastic peak and recheck the alignment of the ion gun. Document result (ion gun aligned).
- Acquire a depth profile on the SiO2 and verify that the sputter rate is at least 300 angstroms per minute at 4kV with no raster. Note that due to the ion current density, the sputter rate will be about the same with the 11-065 COND set to 5.0 (smallest spot) or 3.4 (maximum ion beam current). Document result (ion sputter rate check).
- Remove the SiO2 and Cu sample and install the 1500 LPI magnification standard.
- Adjust the elastic peak on the edge of the holder.
- Increase the beam voltage to 10kV and the COND to about 50. Adjust the electron gun parameters for the best image possible at 5000X and then reduce the magnification to 500X.
- Move the sample until the grid is in the center of the image and bring the stage Z up until it is in focus. Note: Do not change the OBJ or fine focus on the electron gun. The idea is to bring the sample to the focal point of the CMA.
- Run up the magnification until there is only one grid visible and calibrate the magnification for 16.7 uM. Document result (magnification calibration).
- Set the beam current to .05nA (COND near 60) and increase the magnification to 20kX and move to where one grid is being scanned. Adjust the COND and OBJ Steering for minimum image movement. Turn off turbo pump to reduce vibration.
- Set the magnification to 99,999X and acquire a video line scan. Document the results. (Beam size check). Specification is less than 350 angstroms at 10KV.
Summary of checks and calibrations
Cu Energy Calibration
Maximum Beam Current
Cu signal to noise at 10nA and 1nA
Ion gun alignment
Ion gun sputter rate