Christopher,
No luck. There is no metallization that would survive these temps.
You can try silicides or low temperature wafer bonding (plasma assisted)
shay
-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of Christopher Tan
Sent: Tuesday, October 18, 2005 4:55 AM
To: [email protected]
Subject: [mems-talk] Question about metallizations

Hi, I would like to know if anyone had ever done metallizations on Si wafers
where the wafers are later subject to temperatures greater than 800C. I have
a sequence of fabrication steps that require me to metallize the wafer
before bonding the two wafers together. The metal I'm interested in is Al on
Si. I would actually prefer an Au surface, but I would need a diffusion
barrier for Si and Ti, a diffusion barrier for Ti-Pt and then hope that Au
does not evaporate off at those temperatures. So with that respect, I'm just
currently sticking to Al on Si for simplicity. Some of the literature out
there suggests using TiN or TiW. But most of these systems do not
characterize the films at more than 600C. I would like to find out if anyone
has ever done Al on Si wafers at such elevated temperatures for extended
periods of time and what was done to negate the diffusion of Si into Al. I
am unsure of what type of Si bonder my facility will be obtaining, but I
know at least it has to survive 800C.

The Al wafer I require on the surface will probably need to be pure for an
optical reflectivity point of view and thus am unable to use the Si-Al type
depositions. The Si wafer I use is pure undoped Si (>10k Ohms).

Thank you and I apologise for the length of this mail.

Christopher Tan
Purdue University