No, I don't think so.

I electroplate a wafer with 2.5 microns of gold.  Then I apply a photomask,
and electroplate 1 micron of nickel and another 2.5 microns of gold.

In an Iodide etch, the nickel is very clearly etched from the outside in.
If left long enough, (just a few minutes, not enough to etch through the
gold), the top gold piece will simply lift off.  There is no nickel left
attached either to the top gold piece or the bottom gold piece.  Thinner
parts of the pattern lift off first, as the nickel is attacked from the
edges in.

I only got attack of nickel on gold when the nickel was deposited by
electroless deposition, which tends to give a porous and soft nickel.
Electroplated nickel almost always seemed to be good.


David Nemeth
Senior Process Engineer
Sophia Wireless, Inc.
14225-C Sullyfield Circle
Chantilly, VA
Ph: (703) 961-9573 x206
Fax:(703) 961-9576

-----Original Message-----
From: mems-talk-admin@memsnet.org [mailto:mems-talk-admin@memsnet.org]On
Behalf Of Neal Ricks
Sent: Monday, September 09, 2002 3:33 PM
To: mems-talk@memsnet.org
Subject: RE: [mems-talk] Nickel etchant



David,
The KI/I mix is a Gold etchant, so could the effect you've seen be the
result of access to the Gold (i.e. pinholing, lift-off, or undercut of the
Nickel), rather than an electrochemical effect?
Neal
 David Nemeth wrote:In my experience, this solution will not attack Nickel
that is not in
contact with another metal. It will aggressively attack nickel that is
sandwiched between two layers of gold (don't ask me why - go ask an
electrochemist). It will sometimes attack nickel that is on top of gold,
depending on the deposition method of the Nickel.

David Nemeth
Senior Process Engineer
Sophia Wireless, Inc.
14225-C Sullyfield Circle
Chantilly, VA
Ph: (703) 961-9573 x206
Fax:(703) 961-9576

-----Original Message-----
From: mems-talk-admin@memsnet.org [mailto:mems-talk-admin@memsnet.org]On
Behalf Of Phaneendra Medida(fabbi)
Sent: Monday, September 09, 2002 2:47 PM
To: mems-talk@memsnet.org
Subject: [mems-talk] Nickel etchant


Does this solution (KI(Potassium iodide)+I2(Iodine)+Water) Etch Nickel?

Fabbi.