Subject: Re: Problem wbsilicide SNF 2008-04-26 15:00:56: wafer lost drainage did not work
From: John Shott <>
Date: Sun, 27 Apr 2008 10:13:58 -0700


I've extracted your wafers from the hot pot at wbsilicide.  As they were 
in the cassette labeled Gold Contaminated and there was an empty teflon 
cassette in the dump rinser also labeled Gold Contaminated, I placed 
your wafers in that cassette and have left them sitting in water in the 
dump rinser.  I did not want to do anything to try to dry them.

While I'm still looking around, the aspirator seemed to work for me to 
allow me to drain the sulfuric/peroxide from the hot pot.  Although I 
cannot tell what the temperature is, there is an interlock on the 
aspirator that prevents the aspirator from turning on if the acid in the 
hot pot is too hot.  Was the hot pot at something close to 120 degrees C 
when you tried to empty it?  If so, this is likely why it would not 
drain for you.  I think that the maximum temperature at which the acid 
can be drained with an aspirator is either 50 or 80 degrees C ....

In any event, your wafers are sitting in water in a cassette in the dump 
rinser at wbsilicide.

Happy processing,