Isotropic Silicon Wet etch

Rohan D. Kekatpure rohank at
Mon Mar 20 13:39:31 PST 2006

Dear Labmembers,

I need to etch ~1um of silicon isotropically. In literature there seem to be
3 ways of doing it: (a) Wet etching in HNA solution (HF + HNO3 + acetic
acid) (b) Wet etching in EDP solution (Ethylene diamine pyrochatechol) and
(c) dry etching in XeF2. I am flexible as far as requirements of roughness
and dimensional tolerences are concerned. I am just interested in knowing
what options are available to me within our SNF clean room.

My preferred mask would be SiO2. I expect the HF in the HNA solution to
attack the SiO2 mask. So if anybody has an idea on the selectivity between
SiO2 and Si for an HNA etch, I would appreciate the input.

Thank you very much in advance.


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