Dear Sebastion,

I read your question on the MEMS discussion group and i think that you may
be able to produce what you want with some diffusion technique.

There is a Solid Source ceramic wafer that we produce that is suitable for
close space planar diffusion. At temperatures between 900 degrees C and
1200 C this source provides B2O3 glass which is deposited onto the silicon
and diffused. It is possible to achieve a boron concentration on 1.2 ohm
per square without any damage to the silicon slice. You can perform a very
short diffusion-deposition and get 3 micron depth, then strip off the oxide
source with HF and be left with a thin doped silicon layer.

Another method might be to use a Boron Spin on dopant which can provide
about 2.5 ohm per square max without damage to the silicon. This is spun on
a silicon wafer and heated to the temperature of diffusion to yield about a
3 micron depth.

I am not sure if this would be acceptable for you but this might suit your
need. If you are interested to discuss this further you can reach me at the
mail address or telephone Filmtronics my direct dial number is 724 352 3710.

I wish you good luck,

Neal Christensen

At 03:06 PM 9/11/2006 -0400, you wrote:
>Hello,
>
>I need Silicon wafers with a p++ doped membrane of 3-4um thickness (minimum:
>10to20 atoms/cm cubic)
>
>Is anybody able to produce such membranes?
>
>Let me know
>
>
>Cheers
>Sebastian