Plasma Quest update June 27

Len Booth booth at
Thu Jun 27 15:21:00 PDT 2002

Pquest users -

After finding water/glycol leaking out from
under the cathode, I had to remove the cathode
completely from the etch chamber.  A teflon 
cooling line had been leaking onto the chuck
heater wiring (208 vac powered) and broken one
of the leads to one of the 4 cartridge heaters.
Parts are being ordered, and I hope to have the
machine reassembled by next Wednesday 7/3.

Also because of this coolant leak, the problems
associated with RF tuning & DC bias measurement
may have occurred.  We'll know after the cathode
is reassembled and the RF can be tested.

While trying to track down the cause of seemingly
random wafer breakage a week ago, we found that
the pocket machined in the end of the load arm
had been machined incorrectly.  The pocket was
not of a large enough diameter to allow all 4" 
wafers to fit easily.  4" wafers that were near
the upper end of the SEMI specs for prime wafer
diameter would get jammed in the pocket, and 
contribute to the wafer being broken/lost when 
the lift pins & clamp tried to move the wafer.
The pocket has been machined & will now accomodate
all prime wafer stock.

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