> I etched the substrate about 2 min.
If you etched around 80C, 2 min etching in KOH should give you an etched
substrate.
> 1). Etch rate is so small that the substrate is not etched.
Depending on your etch emperature. If you say RT, no way.
> 2). The nature oxide on the substrate is prohibit the
> etching of the substrate.
I do not think so. The native oxide can not sustain in KOH for 2 min at
80C.
I gues the problems are (1) your exposing was not enough,
or (2) your PMMA was a little bit thick,
or (3) your soft baking was done at high temp, or so
long.
Good luck.
============================================
Kiyotaka Mori (Graduate Student)
Dept.of Materials and Nuclear Engineering,
BLDG.090,
University of Maryland at College Park,
College Park, MD 20742
Tel: 301-405-5229
Fax: 301-314-9467
E-mail: mori@eng.umd.edu
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