optimize your photoresist process !!
metal is etched in DRIE and contaminates the chamber.

Quoting "Xiaoguang \"Leo\" Liu" :

> 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.