I'm using the same method.
The machine by STS can reach a very good selectivity to PR, say 150. So I don't
think you need to spin thick resist on your wafer.

By the way, does anybody have some information on conductive polymer, which
contains NO metal?

Thanks a lot!
BR

> From: forzaabbott@gmail.com
> To: mems-talk@memsnet.org
> Date: Tue, 9 Nov 2010 10:27:39 -0700
> Subject: [mems-talk] Through wafer DRIE etching
>
> The project I am working on involves through wafer etching with a DRIE
> machine. I am interested to see how this is done in other facilities.
> My current process involves attaching a patterned piece of silicon to
> another 4" wafer (the only size our STS will accept). I tried spinning
> a thick coat of photoresist on the carrier wafer and exposing an area
> in the middle for my sample (so that I would have better thermal
> contact to the sample. I use cool grease to attach the sample to the
> carrier wafer.) and that seemed to work ok, but there must be a better
> way.
>
> Any ideas?
>
>
> Jonathan Abbott
> jdabbott@byu.net