Wafer chucking after polishing is breaking wafers.
kimsangb at stanford.edu
Sat Mar 1 22:45:09 PST 2008
Dear Gary, Ed and cmp users,
I was polishing my PECVD oxide and nitride wafers today and I broke all of
them while CMPing. The problem seems to be chucking when I raise the head1
up after I am done with the polishing. (As Gary suggested, I manually ran my
wafers.) I know they got broken when it was chucking because there is no
wafer piece on the pad after polishing other than the area below the head1.
Do you have any suggestions to prevent this from happening again?
1) Is it possible to make the vacuum weaker for chucking?
2) Can I turn off the vacuum pump before I raise the head1 so that it
would not chuck the wafer (and break it)?
Also, I will remove my waste carboys on Monday.
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