Hi David,

1) What are the sizes of the holes? 2) What is the wafer thickness? Any
backgrinding done?
3) How many wafers? 4) Any passivation on the wafers? If yes, what type. 5)
Do you have wafers for us to try out?
We did such work before on 6" wafers but no thru holes and only on one side.
>From our assessment, plating up both sides should be achievable. The
coplanarity we achieved was +/-2 um and the wafer edge exclusion zone is
3mm.
If interested e-mail to me Gautham at [email protected]

----- Original Message -----
From: "David Nemeth" 
To: 
Sent: Thursday, May 22, 2003 9:37 PM
Subject: [mems-talk] Electroplating/ thick metal deposition


> 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
>
>
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