On Wed, 22 Oct 2003, Sebastian Sosin wrote:

>     I am designing my firs gas sensor and i want to know if it is possible
> to deposit platinum over polisilicon in order to make a bonding pad.
>     Do I need some other metallic layers between Pt and poli-Si?

An adhesion layer is required. Cr and Ti are popular. Cr resists HF, and
Ti is low-stress. Sometimes people use Ta, but I don't know any of the
specifics of why.

>     Shoul I deposit Au over Pt for the final contacting stage?

That depends on how you want to make contact. Pt is difficult to solder
without special preperation, but I think wire bonding isn't too bad. Gold
is a lot easier to deal with.

>     Where can I find some information for my problem?

You can find plenty of information by reading the archives of *this* list.


Jesse Fowler
  UCLA/MAE Dept., 420 Westwood Plaza, Room 37-129, ENGR IV
  Los Angeles, CA 90095-1597 | (310)825-3977
"Facts are stubborn, but statistics are more pliable."
   -- Mark Twain