Mikas,
For etching Al I have in my lists 10% potassium ferrocyanide (cautions
to avoid any acids due to the generation of poisonous hydrogen cyanide),
19:1:1:2 of phosphoric acid (85%): acetic acid: nitric acid (70%):
water. The second one may still etch GaAs because of phosphoric acid, so
I would try the K3Fe(CN)6.
Best of luck,
David Casale
R&D Engineer
www.maxlevy.com
Max Levy Autograph
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