It is possible to create a vertical wall in a photosensitive polymer using image
reversal.  Using the amplitude of the second exposure as a control, walls from
-22 degrees through vertical up to + 22 degrees are possible.  I have used
positive resist 40 microns thick and created a vertical wall for containment
during copper plating.  Contact me direct for more information.

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@memsnet.org
Sent: Wednesday, September 17, 2008 4:28 PM
To: General MEMS discussion
Subject: Re: [mems-talk] problem in BHF etching

I agree with that.

It's almost impossible to make a vertical wall using BHF on glass.
But if the structure is not that deep,
You can still deposit and pattern some thick metal layer as mask.
Many metal can resist BHF.

Best Regards

Yizhong Wang