Comment pquest SNF 2004-09-01 07:48:02: Chlorine pressure

Jim McVittie mcvittie at snf.stanford.edu
Wed Sep 1 10:34:55 PDT 2004


Elmer,

I suspect that my request to Mike to get the CL2 line back down to 10
psi, where has been for a long time, resulted in the regulator knob
being turned too far. Since it is a long line and all the etchers use
relatively low flows.it took a while for the line to drain. I just
checked the line pressure, it now at 12 psi. Lets stay at this pressure
and see if the GaAs users can ran their processes.  If the minimum flow
is still too high, we will have to go back down to 10 psi.

By the way, I have contacted MKS, who made all the MFCs for the Pquest.
I have asked them about getting a procedure for adjusting the control
valve on the CL2 MFC so we can get the valve to close more and get a
lower minimum flow.

Yesterday, I did talk to an etch engineer with lots of Cl2 MFC
experience. He thought that running at 10 psi was fine as long as we can
make the needed flows on all our etchrers. The fact, that we have been
running with a line pressure of 10psi well over a year with no CL2
problems says that we should be ok. By the way, I checked the CL2 flows
in the main recipes on the other etch tools. They as follows:

Lam poly etch -- 50 sccm CL2 MFC with max process flow of 40 sccm

P5000 - Poly -- 100 sccm Cl2 MFC with max process flow of  20 sccm

P5000 - Al -- 100 sccm Cl2 MFC with max process flow of  30 sccm

PQuest -- 43 sccm Cl2 MFC with max process flow of 20 sccm

Note that only one of the P5000 processs chambers is run at a time. This
means that our max CL2 flow from the source line for all our tool is 90
sccm. I will check that we can deliver the max process flows to all the
etchers at the same time with no problems.

    Jim
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