Dear collegueas,

I have got a problem concerning the etching of silicon. I have a special mask of
PMMA, which
I produce by nanoimprinting (the pattern is only 30-40 nm high). If the mask is
directly onto
the silicon surface the transfer is not sufficient because of the bad
selectivity of silicon over
PMMA (the best I achieved was 1:2). So I thought about a layer between silicon
and PMMA.
The layer has to have a good selectivity over silicon. Furthermore it has to be
at least as fast
as PMMA to be etched, so that the transfer of the mask from the PMMA layer into
the
sacrifical layer is sufficient. I have tried a chromium layer of about 30 nm
thickness, but now I
have the problem to transfer the mask. Every paramter (gas,power,...) I tried to
dryetch with
lead to the destroying of the PMMA and to nearly no effect ofthe chromium.
Has anybody any suggestions???
Thanks a lot in advance