Seh-Won Ahn,
            I have worked with an English engineer who worked for Rockwell High
Resolution division in Texas.  He was using Laser Interferometry and Image
Reversal for 800 Angstrom lines and spaces, 80 nm line, 80 nm space.  Image
Reversal is the key, it allows you to change the profile of the resist line from
the usual poor angle through vertical to an actual overhang.  The results are
predictable and repeatable.  Rockwell high resolution division does not exist
any more and the English engineer went back to England, so I do not know how to
find him.  With any luck he will see this email and offer advice.  I can do the
reversal for you and it the sort of process that can survive travel well.  Let
me know if I can help.  Bill Moffat

-----Original Message-----
From: Seh-Won Ahn [mailto:swahn@lge.com]
Sent: Thursday, March 20, 2003 10:26 PM
To: mems-talk@memsnet.org
Subject: [mems-talk] Photoresist for Laser Interference Lithography



Dear Colleagues,

I have some questions on LIL (Laser Interference Lithography).
I am doing conventional LIL to achieve 200 nm pitch grating.
Could you tell me what kind of photoresist is best for this process?
Wavelength of the laser is 325 nm.
I am using SPR-508A from Shipley.
However, it is difficult to achieve good PR profile.
In addition, will ARC coating under PR be helpful for 200 nm pitch LIL?
Thank you in advance.

Sincerely,
Seh-Won