Why not use lift off.  With image reversal, metal thicknesses in excess
of 13 microns dimensions down to less than 0.1 micron. Cray research
were using for sub 0.1 metal lines for Cray super computer. Easy
repeatable no dimensional variations.  Contact me directly for free
tests and technical papers.


Bill Moffat, CEO
Yield Engineering Systems, Inc.
2185 Oakland Rd., San Jose, CA  95131
(408) 954-8353

-----Original Message-----
From: mems-talk-bounces@memsnet.org
[mailto:mems-talk-bounces@memsnet.org] On Behalf Of X.P. Zhu
Sent: Tuesday, February 14, 2006 1:55 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] Undercut uniformity of Gold wet etching

Hi,
    I am using KI/I2 to etch gold pattern. The thickness of the gold
layer which is on 2 inch wafer is more than 1.5 micron. The etching rate
at the edge of the wafer is faster and in center it is slower. So when
the pattern in center is OK the undercut at the edge will be not
accepted (often > 3 micron). How to reduce the undercut? Thank you for
any advice.

Mopa