RE: alarm "wafer did not drop on blade"
New clamp was installed with reduced contact area to avoid clamp stiction.
Elmer ran a bunch of wafers on "CH. B. Jim-ox" without alarm. wafers did not have resist. No Ar plasma.
Another user after Elmer ran 3 wafers without alarm. Same recipe. 180sec etch. Wafer has:
- 1.5um LTO
- 3um spr220 mask with 2mm EBR
I ran 7 wafers with same layers and resist as previous user.
- alarm went off on 2 of 7 wafers
- first wafer that alarmed went through 60sec etch
- second wafer that alarmed went through 360sec etch
User after me ran 1 wafer twice:
- alarm went off both times
- 1.6um spr3612 resist on 1.5um LTO
- etch times 380sec, 80sec
Result is inconclusive. New clamp still has problem.
Could be 2mm EBR is still too small and one or more teeth of the clamp contacts the resist and releases slightly slower, skewing the wafer placement on the blade.
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