Hello,

You may try NiCr as an adhesive layer. Usually it works fine for gold . Good
luck.

Best regards,
Shimul


--- On Fri, 19/6/09, mikas remeika  wrote:


From: mikas remeika 
Subject: [mems-talk] Gold adhesion to Ti oxide
To: "General MEMS discussion" 
Date: Friday, 19 June, 2009, 9:19 PM


Hello,

does anybody have experience dealing with this kind of issue:

I'm trying to deposit a film of gold on top of a thin film of titanium
(e-beam evaporated), the titanium is exposed to air (and oxygen plasma)
during previous processing, so its inevitable that there is a thin layer of
oxide on the surface of the titanium.

A Gold film is e-beam evaporated onto the surface of the Ti (TiO2).
Resulting film adheres well enough to perform lift-off, however, mechanical
stress such as wireboding results in large sections of the gold film peeling
off.  I have tried evaporating a fresh layer of Ti under the gold (in the
same vacuum), that did not give any improvement in adhesion.  I also have
access to sputtering machines, however in previous experience evaporated
gold adhered more reliably to different surfaces.

So my question - is there are way to treat the titanium/TiO2 surface to
create good adhesion to the gold layer? I have acceess to a range of
materials for sputtering and evaporation, if there is a specific material
that adheres well to both gold and TiO2 I would really like to know what it
is.

Some notes: The sample in this case cannot be heated to more than 100C and
cannot be exposed to RIE type plasma.  Also, it is necessary to have
electrical contact between the gold and titanium (the naturally formed oxide
in this case does not create electrical insulation).