Hotpot repair

Dick Crane rcrane at
Thu Nov 9 12:07:24 PST 2000

Ok, I am the one who stubbed his toe with the inadvertent bench
shutdown. Given the failure (and lack of spares) of the temperature
sensor for the hot pot and the potential danger of wet bench fires
caused by runaway hot pots, I shut down the hot pot heater with the plan
of using the self heating action of the H2SO4/H2O2 4:1 mix to allow
continued operation of the bench. I was not aware of the drain interlock
preventing use of the pot. Shutting down the bench was not the plan and
I am sorry for the inconvenience caused.

I consider the wbdiff to be a tool of prime importance and is one the
highest maintenance priorities in the fab. Replacement sensors have
arrived and will be installed today, 11/9/00. You may notice that the
quartz sheaths are no longer present. The new sensors, with teflon
covers, have worked well in high, minority carrier lifetime processes.
Metallic contamination through the teflon is not a worry for our
operation. Please see me if you have questions.

The future: On Monday on this week, I started reviewing the high
priority tools to insure an adequate supply of spares. The wbdiff will
soon have a stock of controllers, sensors, general parts and, hopefully,
spare hot pots. The goal is high uptime for this important tool.


Dick Crane
technical Director SNF

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