Have you considered NaOH for Al removal?  I am not familiar with using
sapphire as a substrate, but in the optical disc industry we remove Al using
a basic chemistry, not acidic.

We also deal in microlithographic structures so it is useful at those
dimensions.

Good luck!
Robert


> -----Original Message-----
> From: mems-talk-bounces@memsnet.org
> [mailto:mems-talk-bounces@memsnet.org] On Behalf Of Berg, Jordan
> Sent: Wednesday, October 08, 2008 11:48 AM
> To: mems-talk@memsnet.org
> Subject: [mems-talk] PAN etch selectivity over sapphire
>
> Does anyone know if a standard aluminum PAN etch (phosphoric
> acid-acetic acid-nitric acid) will etch or damage a sapphire
> wafer? We are trying to remove a 60 nm-thick aluminum film
> from a sapphire wafer.
>
> Thanks!
> Jordan