Nancy,
If you oxide is good, you will end up having trapped charge, it's a matter
of time and quantity.
The way to avoid it is to supply some leakage mechanism -i.e. high value
resistor in series.
shay

-----Original Message-----
From: Jia, Nancy
Subject: [mems-talk] RE: Charge effects in electrostatic actuators

This is based on a typical MEMS Surface Micromachining Process.   It is
like a parallel capacitor with a fixed polysilicon electrode at the bottom
of the device and a movable doped polysilicon membrane on the top that is
grounded.  There is a thermal oxide or nitride deposited on the fixed
polysilicon to prevent electrical shorting between the two
electrodes.   Hope this give you enough details to answer my original
questions.