Hi Bob,

Thanks for your message very much. I deposited a 250nm-thick Si3N4 as the
masking layer but it could not provide sufficient protection during the KOH
ething. This is partly becaust SiN deposited in our group is not pure
Si3N4, but contains a large amout of oxygen. The patterns are not well
difined using this SiN as the mask. So I am going to try some metals as the
masking layer, say Au/Cr or Au/Ti. Any suggestions? Thanks a lot.

Daxiang

On Jun 1 2005, [email protected] wrote:

> LPCVD Nitride provides the best masking material I have found for deep
> KOH etching. It has very high selectivity to the etch but make sure it is
> thick enough to mask any pinholes in the film. 1500 angstroms should work
> fine. Bob Henderson