From nlatta at stanford.edu  Fri Nov 17 16:21:18 2006
From: nlatta at stanford.edu (Nancy Latta)
Date: Fri, 17 Nov 2006 16:21:18 -0800
Subject: Coil power of of tolerance error
Message-ID: <455E51FE.8050505@stanford.edu>

Folks,

Some of you have been getting an error message which refers to the coil 
power out of tolerance.  What this generally means is the the He 
backside gas leak rate is high.  This may be cause by a bad seal between 
the wafer and the chuck or holder.

Things that you can do if you get this error message are to check the 
placement of your wafer on the chuck and check the backside of your 
wafer.  The backs of your wafers should be clean and free of any 
residual photoresist,  not have any deep etching patterns where the lip 
seal of the chuck comes in contact with the wafer or any other particles 
that might weaken the seal.

If you are using the holder take a look at the back of it.  The backside 
should not have any polymer build up that would affect the seal.  If you 
need to remove the polymer you can do that in the solvent bench using 
IPA and a small piece of Scotch Bright.

-Nancy