Kirt,

Thanks very much for the suggestion. My film is 100-nm thick so a few
second duration etch just might do it. Transene also advertises an "N"
aluminum oxide etchant (so far as I can tell today, it's probably
phosphoric acid + chromic acid to be used at 180-F, this composition
supposedly doesn't etch aluminum. Used in the electrolytic plating
industry to remove anodized aluminum.

If these tricks fail, I will also try ultrasonic wire bonding to see if
one can punch through the native oxide this way.

Thomas E. Wilson
Professor of Physics and Physical Science
Marshall University
One John Marshall Drive
Huntington, WV  25755-2570
Telephone: 304.696.2752
FAX: 304.696.3243

"Four thousand holes in Blackburn, Lancashire
And though the holes were rather small
They had to count them all
Now they know how many holes it takes to fill the Albert Hall [Effect]"
- condensed-matter theorists Lennon and McCartney.




-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Kirt Williams
Sent: Friday, November 12, 2004 7:22 PM
To: General MEMS discussion
Subject: Re: [mems-talk] wet etching the native oxide from
sputteredaluminumthin films

If you don't find anything else, a standard aluminum etchant such as
Transene's Aluminum Etchant Type A, of course is capable of etching the
native oxide as well as the underlying aluminum.
The etch rate at 50 C is about 600 nm/min = 10 nm/s, so a dip of a few
seconds should be sufficient.
    --Kirt Williams

----- Original Message -----
From: "Wilson, Thomas" 
To: 
Sent: Friday, November 12, 2004 9:32 AM
Subject: [mems-talk] wet etching the native oxide from sputtered
aluminumthin films


> I would like to find a suitable wet etchant for the ~5-nm native oxide
> that "rapidly" grows on top of freshly sputtered aluminum upon
exposure
> to air. My hope is that if the wet etch can be done within a minute of
> inserting the sample back into the sputterer loadlock (for the next
> patterning step involving deposition of Cr/Au contact pads), the
native
> oxide will not have time to regrow. The sputterer that I use doesn't
> have a dry etch in-situ capability.
>
> Thomas E. Wilson
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