For etching Ag, and probably Cu, try ferric nitrate {Fe(NO3)3}, about 10
grams or less per liter (depending on desired etch rate).

Thor Osborn, Ph.D.
Manager, MEMS Processing
Microvision, Inc.
19910 North Creek Parkway
P.O. Box 3008
Bothell, WA 98011-3008

TEL.    (425) 415-6725 (Main Office)
TEL.      (206) 685-6649 (Fab Office)
FAX     (425) 415-6602
www.mvis.com


-----Original Message-----
From: Giovanni Zangari [mailto:gzangari@coe.eng.ua.edu]
Sent: Friday, April 30, 1999 9:06 AM
To: MEMS@ISI.EDU
Subject: selective etching of Cu (Ag) over alumina


Hi all:

I am looking for a way to chemically etch Cu (or Ag) deposited onto
a very thin alumina film (~10 nm) obtained by oxidation in air of a
sputtered Al film.
You understand that the alumina layer should absolutely not be
etched by the etching solution for Cu or Ag. I was thinking of
cyanides, but I have some concerns about the safety. I also don't
know what the laws are about the use of cyanides in the US.

Thanks to all of you,

   Giovanni

===================================================
Dr. Giovanni ZANGARI
Assistant Professor
Dept. of Metallurgical and Materials Engineering
University of Alabama
P.O. Box 870202, 120 Bevill Building
Tuscaloosa, AL 35487
Phone:  (205) 348-7074
Fax:    (205) 348-2164
e-mail: gzangari@coe.eng.ua.edu