Photosensitive Polyimide gives near vertical side walls with normal exposure and
development.  If that is not the right angle image reversal allows control of
the side wall angle from a normal side wall through vertical to an acute
overhang.  All with smooth side walls and controllable angle.

Bill Moffat, CEO
Yield Engineering Systems, Inc.
203-A Lawrence Drive, Livermore, CA  94551-5152
(925) 373-8353

www.yieldengineering.com


-----Original Message-----
From: mems-talk-bounces+bmoffat=yieldengineering.com@memsnet.org [mailto:mems-
talk-bounces+bmoffat=yieldengineering.com@memsnet.org] On Behalf Of Pramod Gupta
Sent: Thursday, July 22, 2010 10:07 AM
To: General MEMS discussion
Subject: Re: [mems-talk] rib waveguide using dry etch

Are you trying to etch polymer to make waveguide? If yes, you can try low
pressure/high power process to get vertical wall. But this process also
increases the sidewall roughness. So you have to compromise between your etched
wall angle and side wall roughness. You canmix O2 intoyour SF6 + C4F8chemistry.

Good luck.

With regards,

Pramod Gupta