Hello;

I'm having the classic problem of masking resist failure during Deep RIE
etching (STS Etcher).  I have a 70um thick 4" Silicon substrate that must
be mounted on a handle (carrier) wafer prior to photolith and Deep RIE
etching.  I have experienced repeated failures with resist mounting
(gluing) techniques (presumably from masking resist loss due to
overheating) and am looking for a better mounting procedure or 'glue'.
The wafer must be able to be released easily from the handle after etching
and can not tolerate temperatures over ~170C.

The generic recipe I have used for resist mounting of the thin substrate
is to spin on ~1.6um resist on the handle and to bring the wafers in
contact before baking.  Aluminum foil is placed over the wafer sandwich
and a weight (2 pounds) is placed on the wafers.  The assembly is baked at
100C for 1-3 hours.  I notice significant resist flow (observed after
failure) resulting in poor adhesion and likely poor cooling.

Can you recommend a better glue or gluing technique to address the needs
of thin substrate mounting for Deep RIE etching?

Thank you very much, Jack


        Jack Kotovsky                   (H) (530) 758-6278