>     I was told that the way to make shadow mask is to etch it
> out of thin
> (20-50 micron) stainless steel membrane. How small can be the
> features
> made this way? I will be very grateful for the advice on the
> appropriate etchants and processing. Also, are there any commercial
> vendors that produce them?
>     Thanks in advance
>     Sergei

A vendor for laser cutting of sheet metal is
Acumen Technology, San Jose, CA, (408) 954-8582

A vendor for photo fab on sheet metal is
Kem-Mil-Co, Hayward, CA, (510) 785-2100

I have used neither.

When using the shadow mask during evaporation or sputting,
both the mask and the wafer will heat up.
As the mask is covering the wafer and probably not in great thermal contact,
it will heat more.
Due to different thermal expansion rates, most metals will expand faster than
most substrates (Si TCE = 2.6 ppm/K; amorphous SiO2 TCE = 0.5 ppm/K).
This can cause a blurred shadow pattern.
A low-TCE metal such as Invar (TCE = 1 ppm/K) or Kovar (TCE = 5.1 ppm/K)
is probably better than a random stainless steel (e.g., SS 304 TCE = 17 ppm/K).

        --Kirt Williams Agilent Technologies