This problem can arise if the PR is not completely removed.  Even a thin
layer of scum will act as a mask to KI leaving islands of gold.  Try a good
O2 ashing prior to the dip into KI.  It should only take a couple of minutes
to etch the gold in your KI mix, and a couple of minutes in heated H2O2 to
etch the Ti/W to completely remove your seed layer.

hope this helps,
ADAM

-----Original Message-----

Message: 6
Date: Wed, 5 Dec 2001 14:25:34 +0800 (HKT)
From: mawei 
To: mems-talk@memsnet.org
Subject: [mems-talk] seed layer for electroplating gold

Hello, everyone,

A problem happened when I did my electroplating gold: Before I do the
electroplating, I sputtered a layer of TiW800A/Au2000A for seed layer. And
the I used the thick PR to be the module for plating gold. After finished
the plating, I removed the PR, and want to remove the seed layer also. The
problem happened when I used KI+I2+H2O to etch the seed layer: Gold. I can
never etch them away clearly. How does it happen? Is it possible that
sputtering gold can't be etch by KI+I2+H2O afer being covered by PR or
being dip in the solution for electroplating?

Thank you for your attension.

Best regards,

Vickie

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