Ed:

If you plan to investigate dry etching, reasonable selectivity between
the Au and the Ti should be achievable by adding small amounts of O2 to
the gas chemistry, chlorine or chlorine/argon, for example.  High bias
levels are not generally required to etch gold.  The best anisotropy is
generally achieved at low pressures (sub-20mT).  CCP etchers are
preferable since gold byproducts can coat the source windows in ICP
reactors causing an attenuation of the input power to the plasma and can
ultimately cause damage to the source antenna if the coating on the
window becomes too thick.  Getting low pressure plasmas in a CCP is not
always achievable or straightforward, however.  This is likely to limit
how low in pressure you can go.  Magnetic confinement is often required.

If PR is used for the mask, then you will be making a tradeoff between
the etch rate of the PR mask and the selectivity to the underlying Ti.
As you add small amounts of O2, the Au/Ti selectivity will increase and
the PR removal rate will increase as well.  As you continue to add O2,
you can expect the oxygen to dilute the plasma chemistry resulting in a
reduction in etch rate of the Au.  The problems with mask loss can be
reduced or eliminated if a hard mask is used.

Regards,
Robert

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of
Edmondo Battista
Sent: Monday, September 13, 2010 6:23 AM
To: [email protected]
Subject: [mems-talk] Selective Etching of Gold onto Titanium layer

Dear All,

I would realize patterned structures by selective etching of a
nanometric (10/20/30nm) gold layer deposited onto a titanium layer.

I read some protocols to etch chemically the gold but my question is how
selective is the process toward the gold rather than titanium?

Does anyone know companies that are able to deposit  and pattern in the
metal layer?

Thank you in advance.

Bests
Ed