Hi Lisa,

Something I would try is electrochemical etching in sulfuric acid.
Make your part the anode - the aluminum will anodize and be protected during
Au etching.

Regards,

David Roberts (Wafer Plating Specialist)
Prodigy Surface Tech (408) 469-3203 cell
807 Aldo Ave., Suite 103
Santa Clara, CA 95054
Phone (408) 492-9390
FAX (408) 492-9391

-----Original Message-----
From: Lisa Gades [mailto:gades@aps.anl.gov]
Sent: Monday, February 15, 2010 12:59 PM
To: mems-talk@memsnet.org
Subject: [mems-talk] Wet-chemical etching of Au without etching Al

Hello,

We have a process in which 20nm Au were deposited as a sacrificial layer
on Al.  We need to remove the Au in a later step.  We have found that
iodine-based Au etchant undercuts the Al.  We are looking for a process
that will selectively etch the Au without etching the Al.

Thank you,

Lisa Gades