You can deposite such thick oxide using cvd process. I usually use pecvd to
deposite even thicker oxide layer. To pattern the oxide, we use different
methods,
For oxide thickness of about 4um, you can use RIE with photoresist as a mark. I
never use your photoresist. But it is always possible to spin thicker
photoresist to go along with selectivity. I normally use CHF3 and Ar chemistry
as a receipe.

For thicker oxide, you can deposite amorphous silicon using cvd on the top of
oxide. You can pattern silicon using RIE and the oxide using BOE.

You can also use Au/Cr as a mask to etch oxide in BOE.

Regards,


On 15/12/2008, at 4:35 AM, "Andrea Mazzolari"  wrote:

Hi all,

i need to deposit and pattern 4um of SiO2 on germanium.
Some questions:
1) is it possible to deposit SiO2 on germanium ?
2) is it possible to achieve so thick layers ?
3) is it possible to pattern so thick layers ?

About point 3: i have the possibility to pattern SiO2 with BOE solutions
and S1813 photoresist, but i'm afraid that the photoresist will not
withstand the so long needed etch time.

Best regards,
Andrea