Hi Storas: are you using CH4 instead of CF4 for SiO2 etch? Is it a typo?
----- Original Message -----
From: "Storås Preben" 
To: 
Sent: Sunday, January 25, 2004 10:26 AM
Subject: [mems-talk] problems with RIE grass


> Hello Jiaping Yue,
>
> Could there be a problem with a sputtering effect from the substrate
holder?
>
> I am doing DRIE on 5 x 5 mm areas with the Bosch (C4F8) and Cryo process
> (SF6 + O2). When etching with the Cryo process at 4.0 Pa I got a lot of
> grass, but at 2.8 Pa the surface was nice. It was similar with the Bosch
> process. Thought this might not be helpfull for your SiO2 etch.
>
> Have you tried reduce bias or change pressure?
>
>  I am also doing SiO2 RIE on an AMS200 etcher (C4F8 + CH4), but I had no
> problems with grass on this process.
>
>
> Best luck with your grass fighting
>
> Preben Storas
>