The link doesn't work for me, Dave.  Could you check?

Lisa - that's a tricky one!  I'd always pick Au to beat Al in a chemical
fight.

Any chance you could try a fairly inert dry milling/sputtering process?
  Mind you, that wouldn't give great selectivity either.  If not, you
might find that oxidising the Al will help, as the oxide tends to be
much tougher than the Al.  Or how about another sacrificial layer in
between?

Andy

Dave Lewis wrote:
> Did you try Potassium cyanide (I know it etches Au, Ag, and Cu)?
> Although I wasn't aware that the KI:I:H2O (did you try it in a 2:1:10
> ratio?) etchant would have an affect on Al.  The only other gold etchant
> I'm aware of is Aqua Regia and that will definitely etch your Al also...
> There is a table of etchants located at
> http://grover.mirc.gatech.edu/processing/etchants.pdf
> Good Luck
>
> Regards,
> Dave Lewis