Hi Shifeng,

If you can't find them then they are usually either underexposed (or really a
lot overexposed) or you simply look in the wrong place. What are the dose and
current and how big are your structures?

Another possibility is that there's a problem with SEM imaging (or what do you
use for characterisation?): PMMA is a polymer so you should either use a metal
layer on top (maybe Ti or Al) or you need to use low vacuum. Otherwise charging
effects are too string and you simply burn your PMMA away.

Maria

________________________________

From: [email protected] on behalf of li shifeng
Sent: Tue 25/11/2008 05:12
To: [email protected]
Subject: [mems-talk] EBL on the glass substrate

Hi, guy

I'm trying to write some patterns on glass substrate. Here is my process:

Spin coat 500nm PMMA 950 C4,
Sputtering 5nm gold
EBL exposure
Strip gold using TFA gold etcant for 6 second
Develop in MIBK : IPA= 1:3 for 30 sec

The problem is I cannot find any pattern on the substrate afterwards. What are
the possible reasons for that?  Anyone have similar experiences on this or has a
working recipe to share?

Thanks!