Hello David and Mailing List,
Thanks a lot for your quick response and valuable information (check reply
below and initial question at bottom). Today I tried etching fresh Al pads with
H3P04 17% diluted in H2O at 50 oC. The etch was done within an hour after the
Al depo, and the results were positive this time, with an etch rate of around
300 Angstroms/min and without any signs of etching the In(0.75)Al(0.25)As
semiconductor surface (at least from the alpha-step and optical microscope
feedback). I think that the reason why it didn't etch before was due to a thick
oxide on the Al surface, since the sample with the Al pads was sitting in air
for several months. What do you think?
David, do you know if the solutuion from Transene can break through any oxide
on the Al pads ?
Thanks for your cooperation, this forum is a very efficient and useful source
of information.
Regards
Fernando Camino
David Yackoff wrote:
> Fernando,
> We use Al etch from Transene. Their phone number is (978)777-7860. It's
> premixed, fairly inexpensive, an etch rate of about 5000 angstroms per
> minute at 40C, safely simple for students and they take VISA card for
> payment.
> We heat the bath to 40C with a stirring hot plate and it is in a pyrex tank
> to etch Si substrates with sputtered Al films.
>
> David
>
> Fernando Camino wrote:
>
> > Hello,
> >
> > I want to wet etch (remove completely) and Al mask deposited on
> > In(0.75)Al(0.25)As. I used H3PO4 15% diluted in water, but the etch rate
> > is too slow. I am aware of the mixture 3:3:1:1 H3PO4:HNO3:CH3COOH:H2O.
> > Any special precautions when preparing this solution? Any special order
> > in the preparation? Do you have another solution that might do the job,
> > keeping in mind that I don't want to etch the semiconductor surface?
> > Thanks a lot for your help.
> >
> > Fernando Camino
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