wet etch is not an option?

--
_fm

On 4/7/08, Satish Yeldandi  wrote:
>
> Hi all
>
> I am trying to etch SiO2 using PMMA as mask. I am using ICP RIE system for
> plasma etching. My oxide layer is 250nm thick and the substrate is Si.
> PMMA
> is 180nm thick. PMMA is not holding as a mask. I am not able to etch SiO2
> with this thick PMMA. Can anyone suggest me how to etch SiO2 with this
> thick PMMA as mask.