Sadhana,

The email from Ed made some very good suggestions for rigorously determining the
problem. This might be something much easier to fix though, so I'd try these
simple things first:

1) It's possible this is just a problem with your exposure, which could give
something that looks like "fudging."  You could be exposing with too great a gap
between your mask and your sample. If you know how to adjust this on the aligner
you're using, try reducing it (if not, ask the technician in charge of it, and
they'll know how to change the modes).

2) If that doesn't work, try just extending your development time. Take whatever
you're doing now and double it, and see if it makes any difference (if you have
a microscope with the right filters, check what you're doing as you develop).
Make sure to adequately dry your wafer after developing too. If there's some
water left over, it could make your features look like they've "fudged."

3) Make sure you're cleaning your substrate well enough before use. And, if it's
just Si or glass, use a quick spin of HMDS.

- Kevin

*********************************
Kevin Paul Nichols
MESA+ Institute for Nanotechnology
Mesoscale Chemical Systems
Meander 151
University of Twente
Postbus 217
7500 AE Enschede
The Netherlands

Office: +31 (0)53 489 26 31
Mobile: +31 (0)6 49 312 471
Fax   : +31 (0)53 489 35 95
Email : k.p.nichols@utwente.nl


-----Original Message-----
From: mems-talk-bounces@memsnet.org on behalf of Sadhana Patil
Sent: Fri 10/5/2007 7:44 PM
To: mems-talk@memsnet.org
Subject: [mems-talk] fudging/spreading around the PR features

I am new to Photolithography. I am doing Photolithography with S1813.
Many a times I get fudging/spreading of photoresist around the edge of
the photoresist features after developing. They look more or less like
threads spreading outward from the feature.
Does anyone know what am I doing wrong?