DI water meg ohm meter

Ray Seymour seymour at snf.stanford.edu
Tue Apr 17 07:39:28 PDT 2001

The error message on the spin dryer DI monitor when reading Mohm-cm is
normal as the probe is reading air not water when rinsing has stopped.
Since DI water has a max value of 18.3 Mohm-cm, and air is much higher
value the controller reads ERR to indicate Mohm-cm readings above that
of the purest DI water.
I checked out the spin dryer this morning and found the DI monitor
turned off, and was told that was due to the unit not stopping the rinse
cycle. If the DI monitor is off the rinse stops at the time setting, not
the waste water resistivity setpoint of 16 Mohm-cm.This causes wafers
not fully cleaned to be processed in the furnaces which  may
contaminate  the furnace and any further users wafers.
Please leave the controller on the AUTO setting and allow wafers to
rinse until clean before drying.

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