1. You can use KOH or NaOH solution for wet chemical etching of Al. Even the AZ
series photoresist developers work well for etching of Al because they are also
KOH based solution.

2. Why do you want to use oxidation barrier? If you want to pattern the thick Al
film, you can use photoresist directly on Al film without any oxidation barrier
like Au. For etching the Al film in PR developer or KOH, you have to hard bake
the PR at higher temp.

Let me know if you have any questions.

Thanks.

Pramod Gupta
21084 Red Fir Court
Cupertino, CA 95014
Phone: (408) 253-1646

--- On Tue, 3/15/11, Christian Engel  wrote:


From: Christian Engel 
Subject: [mems-talk] PVD of thick Al-Layer
To: mems-talk@memsnet.org
Date: Tuesday, March 15, 2011, 1:34 PM


Hello everybody,

for a project I need an Al-layer >2,5µm thickness. We are able to do PVD for
this. First question is if anybody has some advices for wet etching? I
thought about using ANPE, but we don't have any eyperiences with such thick
layers. Second question is, if there are any known oxydation barriers I
could use? Perhaps a thin Au-layer could work? But I am concerned about the
high etch-rate of Al in aqua regia, which I would use for etching Au.

Any advice is highly appreciated.

Best regards, Chris