Comment stsetch SNF 2008-01-28 21:56:56: coil power problem

ericp at ericp at
Mon Jan 28 21:56:57 PST 2008

That ain't it.  In the cases I observed, the He flow was 
reading 0.9 - 1.0 during the failure.  (Which is, I believe,
also a problem (related or not), as we've never seen this low reading in the 11 years we've had the machine.)  I am not sure if this reading is the FLOW or the LEAK, but I believe it is FLOW, which is NOT ideally zero. Why was this changed?
It's annoying that this problem keeps getting erased and put back to green, because it is RUINING DEVICE WAFERS.  
Perhaps it's not clear why this intermittent problem has serious consequences even if the plasma only cuts out for a few seconds:  this is a switched process, "etch then passivate then etch then passivate".  If the plasma drops out for 10 seconds, and goes instead "etch then passivate, then passivate, then etch" or "etch then passivate then etch then etch" then our entire etch profile is wrecked, meaning the wafer is scrapped.   The probability of this happening in a typical 1 hour etch is now very high, so the machine is unusable for any fine etching work.  Given that we call this a "NANOfabrication Lab", it only makes sense that such a problem needs to be fixed rather than "observed".  
This problem has been reported for over a month now, and not seriously addressed, while wrecking numerous device wafers. 

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