Comment headway2 SNF 2008-12-10 18:22:17: Planned headway2 upgrades ...

shott at snf.stanford.edu shott at snf.stanford.edu
Wed Dec 10 18:22:17 PST 2008


This afternoon when Gary was cleaning the clogged spindle on the headway, I spent some time discussing some possible improvements that should make it easier to tell when the system is clogged, make it easier to clean when it becomes clogges, and make it less likely that resist in the system migrates any further than need be.
I thought that I'd try to capture some of those suggestions so that we remember the full list.
Possible improvements include:
1. Replace the 90-degree vacuum elbow underneath the spindle with something like a cross which blank off ports on the bottem side away from the spindle and on the side opposite the vacuum line.  When clogged, removing those two caps would make it easier to "rod out" the resist in the spinde.
2. Move the vacuum solenoid into the headcase above the headway rather than in the plenum area.  That will decrease the likelihood of resist getting into the spindle.
3. Insert a "liquid trap" in the vacuum line close to the spinner that would trap any resist that gets into that line.  These might be similar to the little glass traps in the SVG developers.
4. Insert a vacuum gauge close to the solenoid that could be read in the headcase.  This could tell us 3 things:
a. Normal vacuum levels of a clean system no resist in the lines when it was running.
b. Possible indication of a partially clogged system .... I'm not sure that would be the case, but it might be useful to study.
c. Clear indication of a clogged system because it would show vacuum even with no wafer on the chuck.  For these latter 2 features to work it would be useful to add a "Vacuum Test" button that would open the vacuum solenoid (but not turn on the spinner) with no vacuum on a chuck.  In this case, a clean system would show very little vacuum, a partially clogged system would show a somewhat higher vacuum and a fully clogged system would show a vacuum that was quite high.
This "Vacuum Test" button would allow users to determine that t the spindle was clogged before they put their wafers on the chuck which should keep them from having their wafers slide or get thrown off the chuck because there was no vacuum to hold them.
Other suggested improvements are, of course, welcome, but Gary is going to begin to acquire these parts in hopes of making some of these change during the shutdown.
Thanks,
John




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