For short exposures, less than 5 minutes, many resists and any metal
that both adheres to oxide and is resistant to HF will work.  You can
also use layers of these materials as as suggested in other replies.
However, HF will always diffuse through resist given time, usually a
short period of time.  And for metals, the undercut can also be quite
rapid, depending on the amount of tensile stress in those films, which
help the edges peel up slightly to expose more of the interface to the
oxide.


Hiroaki SUZUKI wrote:

>Hi all
>
>Please allow me to ask one simple question. it might be in the past
>discussion...
>What is the best mask material for the glass etching with concentrated HF?
>
>Hiroaki
>
>
>
>