Not without messing up your etched sidewalls. If you need that smoothness at the
bottom, you're better starting with an SOI wafer and the oxide will act as an
etch stop, which can be removed or not. Just be aware that your etched features
will then be undercut at the bottom due to the DRIE footing effect. I am not
sure about your application so if it can tolerate this then that is the best bet

Rick Williston

>>
> Dear all,
>
> After DRIE-etiching of silicon I found that the bottom surface of the etched
area was quite rough (roughness >30nm for etching depth 70µm, roughness
increases with increasing etching depth) . Is there any method to make the
surface smooth (<10nm)?
>
> Thanks!
>
> Regards
>
> Natsuki