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