STSetch2 Status and Update

Mary Tang mtang at stanford.edu
Sat Apr 21 17:48:48 PDT 2012


Dear STSetch2 users:

As you know, the system has not been available for general use since 
just before shutdown in December. The estimate now is that parts are due 
to arrive late next week.  If all is well with assembly, testing, and 
qualification, STSetch2 could be available the following week, the 
beginning of May.   Please check the Daily Etch Status report for 
udpates (left side quick link on the SNF home page.)

We acknowledge we staff have not been noting comments on Coral or 
communicating the situation as diligently as we should.  We WILL do 
better.  Please understand, though, that aside from waiting-for-parts, 
work has been pretty continuous on STSetch2 - with Cesar and Jim McV 
logging in weekends as Mike and Elmer work during the week.

In summary, we believe we've had two problems.  First was a massive 
vacuum chamber leak encountered during the startup.  Troubleshooting 
required two complete teardowns/rebuilds of the vaccum system.  Since 
STS produced very few HRM systems, documentation and spare parts are 
difficult to obtain.  So Mike, Cesar, and Elmer had to learn quickly.  
We've also learned that rebuilding the chamber should be done 
regularly;  seals/orings need to be replaced and deposition in 
inaccessible areas needs to be cleaned.  We suspect that the leaks 
resulted from heating the chamber after being cold for shutdown, 
damaging seals and stressing film buildup.  But Team Etch is confident 
that these leak issues were resolved as of 2 weeks ago.

Second, is the RF generator problem.  This was addressed in early 
December by replacing the generator.  Preliminary tests in Dec. looked 
good and RF match issues appeared resolved.   However, during recent 
process qualification, it was clear that while STSetch2 was etching, it 
was not performing to standard due to generator calibration.  It turns 
out our HRM system uses a prototype DeviceNet version of RF generator 
(which is not supported), so although Elmer got the new generator to 
communicate, calibration was lost.  This generator (which otherwise 
works) has been sent out for recalibration; the original generator 
(which does not) is still out for repair.  A generator is due back late 
next week, according to the latest.

These two problems are independent -- and looking back, their impact 
could have been reduced with more proactive measures.  Some lessons learned:

1.  Chamber rebuild should be part of a regular (annual?) preventive 
maintenance schedule.
2.  Spares should be at the ready -- functional, and completely 
compatible, with repair history.
3.  We need to make better use of Coral and daily reports for 
communicating tool status.

There are ongoing efforts to establish preventive maintenance checklists 
and manage spares on other, higher-utilized etch tools. Given these 
problems, attention will now be focused on STSetch2 and RF generators.  
We regret the problems that STSetch2 downtime has posed for your 
research and ask for your patience as we work through these problems.

Team Etch





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