SEM Source Mechanical Align

Prior status

• just after bake, EHT off current up 246 vs 232
• Gun align near user software limit, stig balance off, time for full align

Align

8 kV aperture image condenser at "max"

aperture positions:

1. 60 um center
2. 20 um right
3. 30 um lower left
4. 75 um lower right
5. 90 um left
6. 120 um top right
7. blank top left

Procedure

First check mechanical alignment, use Si 10 um grid for test

Alignment, all offsets zero user and service. Cond normal

condenser off

Clear problems with mechanical alignment

Bring aperture to exact center, bad illumination

very poor aperture illumination on exact mechanical center

condenser on, illumination distorted here too

Procedure says illumination trumps centering

illumination better but is 120 better than 60??

best mechanical source alignment

after this use gun offset/align for center aperture

Post Bake tests

Problems

• FIG5 ion gun filament burned out
• Sample clips on STM stage too loose for good electrical contact, impossible for STM
• Manifold changes needed, existing manifold not optimized, leaking
• evaporator filaments cross wired, not working

Repairs

• FIG5 filament removed, replace with old 04-303 ionizer assembly, almost identical to FIG5 except 3 post rather than 5 post. Send failed ionized to RBD for rebuild
• Stage removed, clips removed, bent to improve sample plate grab, re-installed
• left clip electrically connected to metal "U", right clip isolated
• tricky to get right clip not to short to U since mounting screw passes through kapton washer into U
• changes to manifold, old stuff mostly removed

Bake

• Set for 72 hours, stopped 6 hours early (clock fast)
• bake into turbos, ion pumps open but off
• nano goes to 3e-5 at full temp, constant during bake
• prep 8e-6, slowly drops to 6e-6
• heat off drops to low 8's, with ion pumps running mid 9's, after TSP high 10's
• next day nano 2.5e-10, prep 3.5e-10
• 
  

Ion Gun

• Brief test of filament before bake, 1 mA emission >> 50 mPa extractor, too much outgassing
• After bake, nano 6e-10, FIG5 pump running
• Turn on 1 mA, grid 150 V, beam 0.5 kV, initially no pressure change, extractor or system
• filament will not come on in standby, must go to etch first. go figure.
• Turn off power supply and software, verify filament continuity, turn back on
• this time it works. probably software. Saved "foundry degass" profile new values
• 150 V grid, 1 mA, 500 V, 100% cond obj
• initial pressure 30 mPa, chamber 1.1e-9, 10:45 am
• pressure exceeds 50 mPa 11:15, gun shuts down self-protect, restart at 0.5 mA, initial pressure 14 mPa
• gun off again after 6 min, reduce emission to 0.2 mA, 28 mPa, later to 0.1 mA at 200 V, emission still > 80 mPa
• pressure peaks around noon, starts slow decline, still 0.1 mA 200 V etch
• 3:45 pm now 1.8 mPa at 25 mA. Note pressure may be normalized by emission current in software, higher current seems to reduce reading
• start to condition HV, pressure about 1 mPa now, 4:45 pm
• OK up to 3 kV, later 5 kV
• extractor still 2 mPa in standby

SEM startup

• connect all cables except detectors, including interlocks and column valve
• switch electronics on to standby, verify column valve closed, switch to on, valve opens
• forgot to start water chiller, SEM water flow error
• start chiller, cycle to standby, restart server, still get flow error
• confirm water is running. Open console whack water flow sensor, right side front behind electronics board, restart, still get flow error
• cycle power 5 times, keep hitting, keep getting flow error
• Remove and dis-assemble and clean flow switch, Gentech International 1 liter/min, closed on flow. No problems with switch.
• Flow is actually low. Run output into bucket, some black powdery crud. Flush with ~ 50 liters water. 
• adjust chiller from 2.6 to 3.3 pressure limit (zeiss spec 3.0 bar)
• disable filter change alarm (we have no filter, its optional)
• Now flow switch works
• Now column valve fails. Limit switch does not light. It did on the first run. Loosen tiny set screw so magnetic indicator works
• Close nano chamber gate valve, let pressure rise to mid 8's so zeiss ion pump will start.
• Start gun ramp up
• quick rise to 156 uA, slower increase to 167 and rising
• EHT on 3 kV, gun pressure 7e-9 mbar
• EHT off, 1:45 after gun start, gun 5.3e-10 mbarr, 209.5 uA at 5.02 kV 2.33 A
• next day 5.4e-10, 246 uA
• prior to bake was 223 to 234 back to Jan 2013, around 230 last six months

Manifold

• Ar source, Nano Ar gun, bypass all connected with VCR manifold
• Pump manifold, air lock, gun connection, Ar source, 4.0e-5 after 45 min, let pump over night.
• Overnight 4.1e-7
• apparent small leak in ion gun branch, close valve drops below 4.0, open after few min up to 5
• close manifold valve, no additional drop
• 
  

Vacuum problems during sample intro

• Granville phillips micro ion gauge controller shows 2e-5 air lock pressure
• degass gauge, jiggle connector cable, no help
• Leave pump running ~ 1.5 hour during sample transfer, analysis, then open gate valve
• prep still 8.8e-6, would expect better
• prep chamber 1.8e-7 (low 10's before opening), consistent with intro gauge
• close gate, pressure drops low 9's prep, increase to 1.7e-5
• Connect VQM cable to prep mass spec, turn on, mostly 18 amu in UHV
• open to air lock, lots of 32, 28, leak...
• pump air lock with prep ion pump, turbo valved off
• now mini IG 4.6e-7, prep 3.8e-8
• close valve to air lock, 14 and 28 drop, 18, 2, 44 relative rise, 1.9e-9
• reopen gate
• prep back to 3.8e-8
• 28, 14, 40, 32 rise, water related peaks fall
• now open turbo pumping valve
• pressure to 2.4e-7 prep, 9.8e-6
• 28, 32, 14 rise, also 40, air leak
• close turbo valve, pressure drops, 5e7 in air lock, 4.6e-8 prep, 14, 28, 32, 40 drop
• even with turbo valve closed, air lock pressure rises rapidly from mid 7's to 5's

Air leak in pumping, probably in manifold

• biggest leak was swagelock connected to mini flange at manifold pumping valve, tighten to reduce manifold to 1.1e-6 from 2e-5. 
• gasket (already suspicious) at 2.75" tee caught between flanges, ie offcenter, replaced.
• marginal improvement, still possible leak in manifold somewhere

Ion Gun trouble

Doing Auger alignment tests on Cu110 single crystal. Lots of carbon, system has been baked, maybe vented, since sample was clean. 64 V LVV peak hard to see.

Manifold

• Ar sample cylinder open, Ar supply valve open, manifold pumping disconnected. This was done when bypass valve connected to air lock pumping some months back.
• Ar supply probably contaminated, maybe missing, i.e. air not Ar
• Disconnect bypass 2.75" VCR flange, add 2.75" tee, reconnect bypass and manifold pump. 
• Turbo pumps down to low 1e-5 in airlock, 14 W turbo, at least no major leak
• Reconnect Ar cylinder/regulator. 
• manifold arrangement bad, no way to isolate Ar supply, need to fix

Electronics

• Electronics start up, software connects, gun to standby, initially ~ 11 mPa, pumps down to zero in ~ hour or less (did not watch)
• Analysis chamber 1.3e-10, after FIG5 pump running a while, ionizer degassed, to 6e-11
• Pressure controller stuck at current limit with software running
• verify cables connected
• verify voltage from ~ 10x10x4 cm USB DAC box on top of 3com switch, voltage 2 V for 20 mPa, etc.
• check output pressure ref from 20-066. Stuck at 10 V, so no pressure control.
• Switch gun briefly from standby to run and back. Now pressure reference works!
• Problem seems to be emission current. Controller cannot maintain 25 mA. 
• Could be result of filament O2 exposure. 
• Can get 20 mA by increasing grid to 180 V from 150 V (range is 120 to 200)
• When emission current out of "green" range, pressure ref goes to 10 V. This may be "fail safe" design...
• Open leak valve 2 full turns, pressure to 4.2 mPa, 
• supply ~ 1 bar relative (regulator), 2 bar absolute
• 2.25 turns, now 33 mPa before controller regulates
• Electronics "click", relay like sound, no clear reason why, its always done this, seems to be associated with cut in ion current.

Test

• 30 degree tilt near center of Cu110 large hole sample holder, excellent auger down to ~ 40 eV. 
• sputter 20 mA "20 mPa" 3 kV 30 sec raster 1x1
• old "scan squares are gone
• Cl peak 180 gone, also O, C reduced
• Cu MVV clear, double peak
• after 6 min C gone

SCA Channel 1 not Working

• While taking Auger data, after doing experiments continuously for a week or so, we noticed channel 1 showed zero counts. (Jan 30 2013)
• Red LED was dark at preamp and receiver for Chan 1, other channels normal
• verified CEM HV cable was connected.
• Opened preamp box, 7 modules, 1 per channel. No visible damage, nothing loose. 
• Tried to measure voltages by connecting preamp SHV connectors to Fluke 80K-40 high voltage probe (1 GOhm impedance) 1000:1 voltage divider with Fluke 179 multimeter, hemisphere at 100 V. 
• Got strange values, ~ 240-300 mV but not stable with time. 
• Expected ~ 1.5 V = 1500 V actual. 
• Channel 1 had only 3.4 mV
• With meter connected, channel indicated counts. All 7 similar.
• With multiplier off, swapped channels 1 & 6. preamp cables. Chan 1 still reports no counts, chan 6 OK. Problem not in UHV
• Swapped HV modules in "1127 Multiplier Supply". Problem moved with HV module
• HV module is defective
• Repair/exchange $750, in stock at Omicron US.
• New module installed 2/11/13, works

CEM Gain Adjust

Modified cover of multiplier supply so that the trimpots to set individual CEM voltages are accessible while the cover is closed. This makes CEM voltage adjustment safe and practical. Supply needs to be pulled halfway out of rack.

• Try to balance CEM signals. Pick flat part of spectrum, CAE mode. 
• Chan 2 is low, adjust to max gain. Adjust other channels to ~ match
• Increase supply knob setting to 9.00. No clear plateau in signal vs voltage

Gun Arc at 30 kV

• On Thursday 12/6/12 low-level radiation group requested SEM be operated at max voltage and current.
• I set the beam voltage to 30 kV. The system had not be operated above 10 kV for some time. Just as the voltage reached 30 kV I heard the "snap" of an arc. The gun went off, there were no error messages.
• I had trouble restarting the gun, I got "EHT Vac not ready" (see previous notes). Raising pressure, restarting PC no help. After putting electronics to standby and back to run, EHT Vac was good, gun started.
• Emission current almost doubled, from ~ 107 uA to ~ 170 uA. I was afraid filament had been damaged during arc, however the same feature was centered in the field of view, and it was possible to get similar image quality. 
• Robert Ribay from Zeiss happened to be working on the Supra, he looked at the image quality, did a quick alignment, and did not see serious problems.

SEM Chiller problem

Chiller was much more noisy that normal in pump room. Disconnect brass pump head from motor. Motor quiet, pump hard to turn manually, "rusty" crud in pump. Must be failing

Pump failed once before, shortly after installation, was replaced by Thermo under warranty.

Ed will order new pump, for now run chiller only when SEM in use, not 24/7

On Thursday, took 3 tries to get chiller to run without alarming for low pressure

Pump replaced Wednesday 12/12/12. Old pump had damaged impeller blades. We also ordered a spare pump.

Gun off for thanksgiving

• Extractor 5.02 kV current 107.2 uA fil 2.33 A 15 Nov 12
• Gun vac 2.72 e-10 system 1.2e-10 before gun off
• Gun vac drops slightly to 2.27 e-10 while gun runs down 

before restart on Mon 26 Oct 12

• Gun vac 1.1e-10, system 1.3e-10, gun vac fluctuates near zero
• have "column pumping" = pumping, "ready", occasionally off, EHT vac ready = no
• Throttle ion pump, open Ar leak valve to get system pressure 1e-8, try to get SEM ion pressure stable above 1e-10. Not enough, pressure (ion pump current monitor) fluctuates below 1e-10
• Have to open pump bypass, get ion pump pressure ~ 3 e-10 with no fluctuations below 1e-10, after ~ 100 sec stable pressure, EHT vac goes to ready, now start gun run up

Extractor reaches 5020 V at 9:50

9:50  78.4 uA

9:53  83.4

9.56  85.2  also close bypass, gun vac 8.8e-11

10:13  92.3

11:48 105.6 close to steady state

On Tuesday, gun 107.8 uA EHT off, 62 uA EHT on 3 kV, 42.5% extraction

Ion Gun Problems

• Ion gun controller has always had relays clicking, anywhere from every hour or so to every minute or so. Ion current drops momentarily to zero on click
• Today (11/8/12) got essentially no ion current at 2 kV, same settings that were good last week
• sample current monitor ~ 1-2 nA, should be 100's
• no SE detected by hemisphere
• changing offset, obj, cond no help
• pressure sensor DID change with gun standby/sputter
• At 2500 V did get sample current ~ 200 nA. 
• Got SE signal earlier in the afternoon, later no signal.
• Shutdown gun and software, restart, no change.

Fixed

• My bad. When rerouting cables, J8 float voltage was attached to transition lens SHV connector. Therefore gun was floating and operating in a weird mode.
• After fixing cable, 3.6 uA by SCM, also lots of counts.
• Relay clicking, current dropping issue still exists.

Auger Problem Deflection

Several problems

• absolute count rate drops
• low KE auger really bad
• Octopole does not have normal effect on counts
• low mag image of #3 aperture offset
• switch back to Cu110 sample, not normal

Deflection voltages

• Xa+ is bad, stuck at -5.5 V from 20 to 100% (load or no load). 10% -1.16, 5% -0.3, 0% +6.8
• Xa- tracks, opposite of Xa+
• Ya+, 0% -1, 10% -.8, 20% to 100% -.4
• Ya- tracks Ya+
• B X&Y stuck at zero independent of control settings.

Ground all 8 electrodes to 'system ground'

Cu110 CRR5 3 kV max, low KE distorted

More or less normal spectra at high KV

Good Cu110 spectrum recorded when quadrupole worked, 30 tilt

Now try to cycle power on PC and EAC

While power is off, remove and physically inspect EAC deflection boards. No visible damage. These seem pure analog, GPIB decode and voltage generation elsewhere? +/- pairs seem to be on deflection boards (op amp circuits)

• Before EIS starts, voltage (disconnected from analyzer) at -40 V on XA+
• Voltages different from before but still bad, should be -40 to + 40 V for 0-100%
• Xa+  0% 7.2, 10% -7.2, 20% and above -15.9; Xa- is opposite
• Ya+ 0% 0 10% -.8, 20% and above -0.4; Ya- tracks
• XY b zero always

Now try ISEM. Do EA SEM image manual deflection, X and Y 25%, values go to -20.0 V for Xa+, Ya+. What does this mean?

Now EIS Octopole control works!!!

Optimize at 80 V, spectrum normal above 135, drops off quickly below that. Nothing below 60 V. Better but still different from before.

residual B field from lens after higher KV operation???

Something charging near sample???

Better with octopole, but problems below 135 eV

ISEM DMA acquisition problems

ISEM DMA modes do not work. Image acquisition otherwise hopelessly slow.

• verify Hsync, Vsync, Pixel clock outputs from Zeiss PC, these look good.
• Pull multichannel receiver out of rack, verify signals arrive on board, they do.\
• Shut down PC and reseat PCI cards (Zeiss control and Omicron data acq)
• this was suggested as a possible fix for detector contrast problem
• Now try ISEM DMA
• now it works. no obvious problem fixed???
• put back in rack, still works

ISEM tests

• image acq will be painfully slow. Test with spectra at, for example, 1 ms acq time. cannot see Si KLL on Si, for example
• with CRR 3 and 25 ms/pixel, can start to see spectra (10 kV max current)
• with 200 ms, not bad
• image time line by line ~ 2-3x raw image time (zeiss) for fast scans, overhead may reduce
• optimal image (no OH) at 0.2 sec, for 2x512x384, around 20 hours...
• there is a line scan mode, can do point by point or line by line, but cannot get line data, only peak/back. No chance for own processing.
• for Au on Si, large backscatter and noise effects, swamps real contrast

To try

• can take reduced image for test
• can modify data 'schema' to get access to raw images peak/back acquired line by line, for post process later
• can try multipoint acq to get family of spectra, but OH and data format may be a pain.
• need to test data export, image dynamic range may be reduced either to 256 or 100 values (bad)

SEM Contrast Problem

• System working normally, then SEM went dark on return from spot mode. 
• Contrast control has no effect. 
• In lens detector no signal
• SE2 detector turns on and off when selected, but SEM software does not control voltage. Good image with manual control.
• Image from Auger detector is good, beam hits sample.
• Exit SmartSEM, restart windows, restart SmartSEM, still broken.

Suspect SmartSEM programing voltage for CEM failed. Fuse??

Check voltages.

Brightness is +2.6 V for 100%, 0 for 50%, -2.6 for 0%, both SED and InLens. This seems right.

(pin to right of center in audio plug)

Contrast (center pin) is stuck at 1.92 V for SED and between 0.51 and 0.74 V (non linear) for InLens

Both should be 0 to +5 V for for 0 to 100%.

HV Monitor on Supra is +1.227 V for 100%, 0.314 for 25%.

On InLens is +0.018 V. 

work around

still no news from Omicron 11/8/12

Run SED in local mode, works, but must remember to shut down if not required, for sputter, etc. Also no brightness control.

Modify InLens, open housing, disconnect voltage monitor wire and use BNC for external brightness control. Write external LabView app to control voltage.

Turbo Pump Problem

• Prep chamber turbo did not pump down. Stalled at a few thousand RPM, ~ 40 Watts, bearings started to heat. Weird noise. Possibly scroll pump did not start. Foreline pressure gauge showed ATM. Airlock pressure ~ 25 Torr.
• Cycled power on pump. Now system goes to full speed eventually, but power stays at 66 W instead of dropping to 12-18 W. Foreline still showed ATM.
• Swapped scroll pumps for nano and prep. Start pumps together. Now both start normally, foreline pressures 0.13 mBarr prep (with nano scroll), 0.19  nano (with prep scroll). Both turbos ~ 15+-3 W, normal. Ultimate foreline pressure was ~ 0.055 mBarr, or 0.075 during bake.
• Possibly scroll pumps have trouble, or roughing lines leaking due to sharp bend on hoses. Exchanging scroll pumps seemed to fix problem. need to invert pumps again.

Let turbos run. Both prep and nano running about 10 W next day.

On Friday 10/26 switch scroll pumps back. Now prep turbo is slow to start, eventually reaches 100% with 88 W power. Prep pirani reads "atm". Shut down, disconnect scroll, pull out from rack, clean and reconnect quickflange with no stress on hose. Try again. Better, quick pump down, standby 18 W, foreline 0.10 mbar by pirani

problem was bad foreline pressure, possibly due to leak from strained hose. 

More trouble Nov 8, 2012

• Try to start turbo. Stalls at 63 W 27%. Pirani reads ATM. 
• Vent and retry. Similar results. Airlock shows ~ 10-15 torr.
• Stop again, examine turbo. Remove hose from scroll pump. Near pump the transparent plastic hose looks "misty". Remove hose, moisture condensed on inside ???.
• Reconnect hose, try again. This time system pumps down, foreline pirani indicates rapidly (< 60 s), goes below 0.5 mbar, pump reaches 100%.
• Then power and foreline pressure increase, ~ 40W at 100%, foreline 1.1 to 1.2 to 1.5 to 1.7 mBar over several minutes 
• This is very strange.
• Stop turbo, disconnect foreline, try again. This time 19W at 100%, foreline 0.16 mB and dropping slowly (normal).
• Possibly some water condensed in scroll pump when foreline was leaking, now being slowly pumped away. 
• after one hour foreline 0.12 mB, 17 W