PQuest clamp sensor problem

Luigi Scaccabarozzi scaccag at tiscalinet.it
Thu Jun 21 15:31:57 PDT 2001

Hi Janice,
about the temperature, did you check the cooling system set temperature?
It may have been set at very low temperature, and the jump to high
temperature may be due to wrong reading, sometimes it happens.

About the clamp down sensor, most probably it is due to incorrect
calibration of the sensor. Waiting for recalibration, usually just pushing
gently  the sensor with your finger will make it "sense" the correct
position. You can see the sensor just under the chamber, as a small motor
and 3 light sources. You can see it moving when loading or unloading. I
showed it once to Matt, so you can also speak with him.
I don't think these pronblems are related to sticking wafers, but I may be
Hope this will help,
good luck

----- Original Message -----
From: "Janice Catherine Wynn" <jwynn at stanford.edu>
To: <pquest at snf.stanford.edu>
Sent: Thursday, June 21, 2001 9:35 PM
Subject: PQuest clamp sensor problem

> To PQuest users,
> I've had problems with the PlasmaQuest today, and thought perhaps someone
> would know what is wrong.  (Len is gone until 7/1).
> I first ran a dummy wafer for 2 min.  All seemed reasonable except the
> temp reading on the monitor went to 0.3C during the process, and then shot
> up to 38C when finished.  The cooling mixture was stable at 20C and my
> temp was set to 25C in the recipe, so I thought it odd that it went
> sharply to 0C.  I mention this because it may be related to the next
> problem....
> The next time I loaded the dummy wafer, it loaded fine and the clamp came
> down.  However, the program stopped on the step "Waiting for the Clamp
> Down Sensor."  Eventually (almost waiting 10 min) I hit esc to stop it and
> unloaded the wafer.  I tried 2 more times, always with the same problem (I
> tried cleaning the wafer before the 3rd try).
> Any suggestions for the temperature or the clamp problem?  Thanks.
> My only idea is that the temp really did get low for some reason and the
> mixture condensed on the clamp sensor.  I don't know if that's possible
> from the geometry.  I will try to run it again later this afternoon after
> it's been pumping for awhile.
> Thanks for any comments,
> Janice Wynn
> ---------------------
> Janice C. Wynn
> Physics PhD Candidate
> Stanford University
> McCullough Bldg 018
> Stanford, CA  94305
> lab: (650) 723-4012
> fax: (650) 725-2189
> jwynn at stanford.edu
> ---------------------

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