You may want to consider outsourcing your effort to a foundry service that has
lisenced the Bosch process (like me).  8 microns is not very deep however, so
you may have luck using the Black Silicon Method as described in a series of
papers out of the University of Twente.
Basically:    step1 = find the SF6/O2 ratio where the micromasking of dust on
your surface causes pilars of Silicon to be left behind and give the surface a
black appearance.  This also signals achieving anisotropy.
                   step2 = Add CHF3 to undercut the dust until the black
appearance cleans up.

good luck
Neal Ricks
Haleos, Inc.


  Peng Yao  wrote: Hi,
I want to use bosch to fabricate my structures for vertical sidewalls. I
have an ordinary RIE system. And I plan to use SF6+He to etch silicon and
CF4+H2 to form the sidewall passivation polymer. And I am going to use
photoresist as the mask during etching. The thickness I needed is about 8
microns.
Because I don't have any experiences of bosch etching, any suggestion will
be very helpful. And I really need some point to start with.
Thanks a lot!

Peng Yao
DOEs lab
Electrical Engineering Dept.
Univeristy of delaware
Newark D.E 19716
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