Photoresist does not hold up well to unbuffered HF.  You should use BOE
(HF with NH4F) to pattern SiO2 with resist mask.

Roger Shile

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Daniel L Baptista
Sent: Thursday, October 28, 2004 1:27 AM
To: [email protected]
Subject: [mems-talk] choosing a good resist

Dear all

I will use a resist on a SiO2 thin layer on a Si substrate. I will
perform
e-beam and single ion lithography to create nanoporous trough the
resist.
Then I need to over-etch the SiO2 layer to produce an undercut. Finally
I
will evaporate metal and lift off the resist. The problem is that using
HF
to etch the SiO2 probably the resist can be affected. My question is
what
resist I should use in this situation. PMMA is good for e-beam but I am
not
sure if it is affected by HF. Could you help me?

Thanks a lot!

Daniel

University of Cambridge, UK
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