Zhu,

Transene makes a Ni etch which they claim will not harm III-V material.
I have used it and it seems fine.  I have seen 20 to 30A of my epi
getting etched depending on what layer I'm on.

Brent

"X.P. Zhu" wrote:

>    I want to pattern Ni film on GaAs substrate by wet
> etching. The one micron thick film was deposited by
> E-beam. I used diluted HCl and H2SO4 and they did
> work, but H2 bubbles generated during the etching
> procedure made effect on the etching uniformity: they
> all attached to the wafer surface. How to do with
> these bubble? Or are there any other etchants which
> can etch Ni but not GaAs, and don't release bubbles
> during etching? Thanks!