Hi Li,

I have tried to use DRIE to etch silicon probe tips with metal mask
and experienced from loading effect to grass effect. Basically, you
need a good balance between the SF6 and C4F8 flows. Please check one
of my publication for more details:

Fei Wang, Xinxin Li, Nanxiang Guo, Yuelin Wang, and Songlin Feng, “A
silicon cantilever probe card with tip-to-pad electric feed-through
and automatic isolation of the metal coating,” Journal of
Micromechanics and Microengineering, Volume 16, Issue 7, pp.
1215-1220, 2006.

Hope it helps, good luck!

Fei

2010/2/20, Li. Zhang :
> Hey Renil,
>
> The hard mask is sputtered Al with thickness of 1500A and the the depth
> etched down to silicon is about 10um.
>
> I applied an etching cycle of 3s and a passivation cycle of 1s. The flow
> rate of SF6 = 200sccm and C4F8 = 100sccm.
>
> I've heard lowing the passivation flow rate might help with grass problem,
> but not quite sure.
>
> My Best,
>
> Li. Zhang

--
Best regards,
Yours sincerely
Fei Wang
______________
Postdoctoral researcher, Dr
MIC - Department of Micro and Nanotechnology
Technical University of Denmark (DTU)
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