Raith UPDATE 8272004: 2245 hrs RAITH system returning to operational status, hopefully access starts SAT afternoon.
jwc at snf.stanford.edu
Fri Aug 27 23:27:27 PDT 2004
Greetings Raith Users:
We worked long into the evening today to ensure we reached operational
status this weekend.
A number of problems have been encountered and corrected. Please take a
look at my white board ion my office if you wish to review the sequence
of problems and how we fish boned out a solution. It was an
'interesting' exercise to say the least.
1. Significant contamination was introduced into the system from Carbon
dots, contaminated fixturing and user supplied hold downs, and possibly
several instances of unbaked or poorly baked resist being placed into
the system. These events occurred August 6, 10, and 11 on SNF users runs.
Troubleshooting was complicated by users reports of charging and beam
drift in the system but some of these reports came from users working
with thick oxide, nitride, and SOI substrates and they were experiencing
simple and normal sample surface charging.
2. A problem with the electrical circuit supplying the Neslab chiller
unit in the service chase caused the chiller unit to go into a Low
Temperature fault condition. The cooling lines to the Electron Optics
Card and the turbo pump condensed water on their exterior surfaces and a
drop or drop of water dripped into the E/O card loosing control of that
subsystem particularly in the Y scan control. This may have been
intermittent but the first alarm in the LEO server tripped on Monday
August 16, 2004 at 11:37 AM.
Repairs were effected to the column by performing another inspect,
clean, and vacuuming of the upper section of the LEO column and over 50
hours of bake outs in three sequences to bake out the column and remove
contamination, presumably hydrocarbon from this area. The E/O card was
replaced. Three known good chiller units were exchanged before we
identified the bad circuit in the chase leading to the chiller
failures. Tonight we ran an independent AC cord to this last unit (#4)
and this corrected the situation.
A qualification run made last night on a standby jury rigged water
recirculation unit after other repairs and calibrations were completed
has met with my satisfaction and has passed High Power Microscope
inspection. We appear to be within specifications for the system.
We brought the FE-Gun back up at 9:00 PM and will allow it to run
overnight and will recalibrate the E/O card and check out the system.
We should be back up and available to users by mid afternoon.
The following restrictions are in effect until my return September 13,
2004 with no exceptions whatsoever:
As that Contamination caused the bulk of the problems we experienced in
the last three weeks I am increasing the stringency of cleanliness
requirements to normal practices for Ultra High Vacuum systems:
ABSOLUTELY NO CARBON DOTS, TAPE, STRIPS OF CARBON OR ADHESIVE ARE TO BE
PlACED INTO THE SYSTEM. NO EXCEPTIONS...
ABSOLUTELY NO BRASS, BRONZE, OR OTHER HOLD DOWN FIXTURES IN THE SYSTEM.
ABSOLUTELY NO ADDITIONAL FIXTURES, HOLDERS, OR MOUNTS ARE TO BE PLACES
IN THE SYSTEM.
NO RESIST THAT HAS NOT BEEN BAKED AT TEMPERATURES ABOVE 150 DEGREES
CELSIUS WILL BE ALLOWED INTO THE SYSTEM.
ALL PREVIOUS INDIVIDUAL PERMISSIONS OR EXCEPTIONS TO THESE RULES AR
IF YOU CANNOT FOLLOW THESE SIMPLE GUIDELINES TAKE YOUR PROJECT
UPON MY RETURN, WE WILL REVIEW THESE RESTRICTIONS AND MAY AMEND AND/OR
MODIFY AS SUITS THE NEEDS OF THE LAB MEMBERS, AND THE NECESSITY TO
MAINTAIN CLEANLINESS AND GOOD VACUUM PRACTICE FOR THE BETTER GOOD AND
UTILITY OF THE RAITH USER COMMUNITY AND THE HEALTH OF THE RAITH 150 SYSTEM.
Thank you to everyone for your support through this difficult time. I
am going on leave and will return Monday September 13, 2004 resuming
with my office hour at 8:30 AM.
ARVIND and GIGI are in charge during my absence.
If you run into problems follow the "Who are you going to call
procedures..." posted in the Ebeam Lab and attached...
Ebeam Technology Group
Stanford Nanofabrication Facility.
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