From shott at stanford.edu  Wed Aug 27 19:59:54 2008
From: shott at stanford.edu (John Shott)
Date: Wed, 27 Aug 2008 19:59:54 -0700
Subject: Matching network repaired ....
Message-ID: <48B614AA.2090008@stanford.edu>

Lampoly community:

I know that a number of your are anxiously awaiting the return to 
service of the lampoly etcher.  The main matching network was pretty 
well destroyed .... the high-power vacuum tuning capacitor was so badly 
overheated that it broke it's metal-to-ceramic seal and scorched some of 
the ardel insulating parts.

Cesar has replaced the tuning cap with a new Jennings 3-30 pf variable 
cap. This cap takes 18 turns to tune from 3-30 pf .... but the Lampoly 
can only mechanically tune over about 6 turns. Unfortunately, Lam could 
not tell us how to properly preset this capacitor so that it is 
guaranteed to be in it's tuning range.  Jim McVittie and his magical HP 
4815A RF Vector Impedance Voltmeter bailed us out in this case ... At 
this point, Cesar reports that we are seeing good, crisp matching 
performance on all of the recipes that he has tried.   Please monitor 
your processes carefully, however, as we have likely not tested the 
entire range of processes that are in use.

Finally, please remember to keep your eye on these etching tools.  When things go wrong with RF components, things can get damaged and overheat in a big hurry and alert monitoring of these tools will often save us serious problems.

While I will double check this with Mary, Jim, and the other etch process folks, it is my belief that this repair should not require process re-qualification: we haven't tinkered with the chamber, gas flows, power supplies etc .... I think that it was only the matching network that was damaged and then repaired.

Of course, cautious processing always calls for carefully checking the process under your conditions before committing your important wafers.

So, thanks to Cesar and Jim McVittie for their good work .... and we wish you happy etching.

John