Hello Francois,

I have had no trouble doing ebeam lithography on glass when I coat the PMMA
with 10 nm Aluminum.  You have 10 nm metal under the PMMA--that should be
fine if the metal is fairly conductive (if not, try putting 10 nm Al on TOP
of the PMMA--it is easy to strip off in KOH prior to developing the PMMA).
I have used 50 kV and 100 - 250 pA beam current.  Proximity effects, in my
case, were not any different than on a silicon substrate.

With the metal on TOP of the PMMA, I can make an electrical contact from
that metal to the sample holder of the ebeam system using a metal clip.  In
your case, you may not have any electrical contact between your metal and
the sample holder.  Try using a metal coating on top of the PMMA (in
addition).

Good luck,
Bill Lanford-Crick

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Francois Montaigne
Sent: Tuesday, August 17, 2004 10:31 AM
To: [email protected]
Subject: [mems-talk] Ebeam lithography on glass substrates


Hi,
We are currently trying to do Ebeam lithography on metallic layers (about
10 nm thick). We use PMMA resist and 30 keV electron energy. Whereas we
obtain good results with silicon substrates (18-30 ohm.cm), the patterns
are dramatically rounded on glass substrates. Can it be du to a dramatic
proximity effect on glass? We rather suspect that some charges are trapped
in the substrate despite the conductive metallic layer between the
substrate and the resist. Does some of you have any experience with Ebeam
lithography on glass or insulator substrates or can advise any reference on
that subject?
Regards
Francois

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