Ti, Cr, Al and Ta metals are used generally as adhesion layers because
they are extremely reactive to trace oxygen and form metal-oxide-SiO2
interfaces.  You need some metal that will form a covalent oxide bond to
the SiO2 surface and also will alloy with Pt.  Noble metals such as Pd
might not form a strong oxide. For example, Ni does not adhere strongly,
and therefore needs an adhesion layer. Pt and Pd are in the same group.
Another approach may be to use high energy sputtering, such as pulse
sputtering.  That method was used to make Ni metal adhere to lithium
niobate without an adhesion layer.

Good luck.

Don Friedrich
JDSU
Santa Rosa, Ca
[email protected]

-----Original Message-----
From: Taekyung Kim [mailto:[email protected]]
Sent: Wednesday, March 18, 2009 9:20 AM
To: [email protected]
Subject: [mems-talk] Pd as an adhesion layer?

Hello folks,

I am looking for an adhesion layer between SiO2 and Pt.
Since my process restriction, I can't use Ti, Cr, and Al.
Is Pd a fairly good adhesion material for Pt-SiO2?

Thanks

TK