If you have 1500A Au seed layer over 800A Ti adhesion layer and you have
reasonable contacts on the edge of the wafer you should have no problems
with electroplating gold (assuming you solution is OK). The problem you
describe appears to be surface contamination of Au seed layer. Excess
current over accessible Au causes local delamination and exposes the
underlaying Ti. You have a few options including either to use a commercial
wafer cleaner or apply an oxygen plasma cleaning step prior to
electroplating.

Igor Kadija
www.fibrotools.com

----- Original Message -----
From: "Robert Dean" 
To: "General MEMS discussion" 
Sent: Wednesday, October 06, 2004 9:39 AM
Subject: [mems-talk] problems with gold plating


> Hello,
>
> For a MEMS die bonding application, we need to plate 2um of Au onto a flat
> silicon die cap that has TiAu (800A /1500A) E-beam deposited onto the SiO2
> surface layer.  We are attempting to electroplate gold onto the entire
> surface, i.e. no photoresist mold.  When we have the current set low, we
> only get gold plated in a few islands.  When we increase the current until
> we start getting uniform plating on the entire surface, we soon get one or
> more black spots that grow in size and limit the plating.  Any
suggestions?
>
> Sincerely,
>
> Robert Dean
> Auburn University
>
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