Hello,

I am looking for a vendor with expertise in depositing thick layers (5
microns) of gold on 4" and 6" silicon wafers.  The metal does not have  to
be patterned, but the wafers have been etched all the way through with KOH.
The metal deposition has to be on both sides of the wafer.  The seed layer ,
and any underlying dielectric layers, can be anything.

We have tried electroplating in-house in the past, with a Chrome-Gold seed
layer on top of bare silicon, but found that the adhesion suffered greatly.
The adhesion of the base film of 1000 A Chrome and 1000 A gold was
excellent, and passed the tape test.  We played around with current density
and plating times, and occasionally got some good adhesion, but nothing was
consistent.  We've also had a vendor use e-beam evaporation, but again with
mixed results.  The films were stressed, which I fear may fundementally
limit the adhesion, especially with larger wafers.

We do not have the tools to closely monitor the state of the plating
solution.  So the question I'd like to pose is this: does anyone know of a
vendor that could deposit thick gold, preferably by electroplating, on 4"
and 6" silicon wafers with consistently good adhesion?  The gold surface
should be as smooth as possible (we'd like to do gold to gold
thermocompression bonding on the wafers).  We're looking for a process we
can ramp into production.

Any help is appreciated.  Thanks!


David Nemeth
Senior Engineer
Sophia Wireless, Inc.
14225-C Sullyfield Circle
Chantilly, VA
703 961 9573 X206