[labnetwork] Deep anisotropic etching of SiO2

[Ningzhi Xie]

 Dear college,

We want to perform a highly anisotropic, very deep (~500um) etching of SiO2
with a vertical side wall. On top of the SiO2 is nanostructures
protected by photoresist. The etch depth needs to be controlled with a
precision of 20% (we are thinking of using another  material as the
substrate underneath the SiO2 layer, which acts as an etch-stopper). The
structure and dimensions are shown in the attached image. It would be very
helpful if anyone has any idea of this kind of etching (either dry and wet
chemical etch is fine).

Thank you very much.

Best regards,
Ningzhi Xie
Department of Electrical and Computer Engineering
University of Washington
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