Raith UPDATE 8272004: 2245 hrs RAITH system returning to operational status, hopefully access starts SAT afternoon.

James Conway 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.

Diagnosis:

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 
HEREBY REVOKED.


    IF YOU CANNOT FOLLOW THESE SIMPLE GUIDELINES TAKE YOUR PROJECT
    ELSEWHERE...


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...

Thank you,

James Conway
Ebeam Technology Group
Stanford Nanofabrication Facility.







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