Dear all,

I am currently trying to alter the surface properties of pyrex wafers from
hydrophilic to hydrophobic (contact angle > 100°). I need to coat one side
of the wafer and structure the layer either by RIE or a lift-off process
using photoresist as a sacrificial layer.
I already tried to deposit teflon-like layers from c4f8 in a DRIE-tool.
But these layers will not stick to the pyrex after lift-off in acetone and
rinsing in water. Same with HMDS, deposited from the gas phase at 140°C.
The c4f8-plasma deposited layers adhere perfectly to silicon by the way.

Does anybody have experience with depositing and structuring teflon-like
layers on pyrex or can anybody suggest any adhesion promoter or surface
treatment of the pyrex to increase the adhesion of the hydrophobic coating?

Thanks for your help,


Marco