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
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