HI Xiaoguang,

You can use a combination of thermal oxide and photoresist as etching mask.
I have done through-wafer etching upto 500 um (diameter 40-50 um) depth
using 1.8 um thermal oxide + 10 um AZ9260 as etching mask. Etching profile
and results were ok in my case.

Let me know if you need any other information.

Thanks,
Pradeep Dixit,
Nanyang Technological University,
Singapore



On 9/1/06, Xiaoguang Leo Liu  wrote:
>
> Dear all
> I'm trying to do a  through wafer etch (550um) using silicon Deep RIE.
> I've tried with the AZ9260 photoresist. However, the reflow of the
> photoresist after hard bake makes the etching profile non-uniform.
>
> Does anybody know if metal can be used in the DRIE process. I've heard
> that people have done 2mm etching using Ni as a mask. However, our
> staff here says metal is not allowed in the chamber. It would be great
> if anybody could give some references on that.