I know that PDMS is etchable in O2 plasma; a member of our research group
has done this before. Etch rate probably varies a lot depending on your
chamber, gas mixture, and sample size. However, there is suspicion
in our group that this etching method causes redeposition of polymer on
the chamber walls, which can lead to performance problems in other
processes using this same chamber.

This brings me to my question, probably more for Heiko. Do fluoride-based
etchants change the PDMS surface properties? I know that oxygen plasma
treatment is often used to make PDMS hydrophilic, but for the reason
above, there's no way I can bring PDMS samples within a mile of any of our
plasma-generating equipment.

Alik Widge
MEMS Laboratory
Carnegie Mellon University
alik@cs.cmu.edu