PQuest Preventive Maintenance

Jim McVittie mcvittie at snf.stanford.edu
Wed Mar 29 10:06:54 PST 2006


I think improved maintenance of the PQ is fine but one has to be careful of not
get into unintended consequences, which degrade etch processes. One really does
not want to be opening a Cl etch chamber unless one has to. There are 2 issues.
First, you will introduce water from the cleaning process and second, you will
change the surface chemistry of the chamber walls. Some processes are very
sensitive to the water level in the chamber and all the processes are sensitive
to wall surface chemistry. So the result is it takes a good effort to get a
chamber back to where it should be after a wet clean.  For the Lam etcher, we
were given a 2 page procedure from Lam called “Post We-Clean Chamber Recovery
and Seasoning” to be done after every wet clean. This procedure recommends
running 25 wafers under various conditions.  Although we are not going to run
25 wafers through this system, we need to develop a similar procedure for the
PQ.  I recommend that any chamber cleaning be based on process needs and not on
an arbitrary time bases.


Ed Myers wrote:

> PQuest Users,
> Does the PQuest community want the SNF staff to schedule regular preventive
> maintenance on the PQuest chamber?
> A month ago Ceser cleaned the PQuest chamber after we received some
> complaints on repeatability of an etch process.  Apparently, this had a
> very positive effect on the user's etch.  The SNF staff would like to take
> on more responsibility in maintaining the chamber condition, if it is
> agreeable with the PQuest community.  I'm told that manual cleaning of the
> chamber is very unpleasant.  The proposed approach would mix in manual
> chamber cleans along with evaluation of a shutdown-chamber clean recipe
> similar to what Elmer added to the AMT etcher.
> We will plan on implementing a preventive maintenance program unless we
> hear objections from the PQuest user community.  We are also looking for a
> champion to help us design and evaluate the effects of any preventive
> maintenance.
> Regards,
> Ed

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