STSetch2 Status and Update
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
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.
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