Dear colleagues,

We were trying to do some ebeam lithography in PMMA950C5 spun on an Al
coated wafer. When we were etching Al after the PMMA development, the PMMA
changed colors and was apparently attacked. As far as I know, Al deposition
on PMMA with non-conductive substrate to improve the EBL resolution is a
very common process, then how come the Al etchant attacks the PMMA? The
etchant we used is "Aluminum Etchant Type A" from Transene.

Any suggestion to avoid this attack is appreciated.

Hongjun,

------------------------------------
Hongjun Zeng, PhD
MEMS/Nano Scientist
Nanotechnology Core Facility
(NCF formerly MAL)
University of Illinois at Chicago
3064 ERF Building
842 W. Taylor St., Chicago, IL 60607
Tel. 312-355-1259, Fax: 312-413-0447
------------------------------------