Hi,

I did that before. Parylene is not attacked by KOH, but the
parylene/silicon interface is (pretty fast). If you etch through the
whole thickness you'd better stop the KOH etching before you reach the
parylene (say when 10-20 Microns are left). You can then use gas-phase
or plasma to finish the etching. Also, I would suggest having a ring of
silicon dioxide on the edge of the front side (the parylene/Si02
interface didn't seem to be attacked).

Matthieu

Gang Li wrote:

>Dear all,
>
>Can parylene be used to protect frontside of the wafers when
>you carry on etching trough the wafers from the backside?
>Any information will be appreciated greatly.
>
>Regards,
>
>Li Gang
>
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