[mems-talk] step coverage on DRIE topography

[Nicolas Duarte]

How deep are you etching?  10 um might be possible to get a 
continuous film with sputtering, but 100 um pits would be much less 
likely.  The aspect ratio also plays a factor here.

The other big question is if you are using the Bosch process or a 
cryo process.  Bosh creates scalloped side walls that would be more 
difficult to coat continuously (not to mention it leaves behind a 
polymer that would give you problems with adhesion).  The cryo 
process would over all be better in this situation if you had a 
choice.

However, the best way to go about this would be to start with a doped 
SOI wafer so that way when you etch through the top doped layer you 
already have a conductive mass that can be electrostatically 
actuated.  This way you don't have to worry about depth (other than 
having the depth of your top SOI layer be sufficient), aspect ratio, 
scalloping, or adhesion.

Nicolas "Nik" Duarte
Ph.D. candidate at the Pennsylvania State University
Department of Electrical Engineering

At 6:26 PM -0700 9/9/07, kris wrote:
>Hello All,
>
>I was wondering if we can get a continuous thin metal
>film (sputtering or evaporation)on the top of the
>silicon wafer that is subjected to DRIE in STS system.
>
>
>The released DRIE`d structures should be conductive
>for the actuation with the adjacent substrate.