> -----Original Message-----
> From: Sampo Tuukkanen [mailto:sampo.tuukkanen@phys.jyu.fi]
> Sent: Monday, December 30, 2002 10:38 AM
> To: MemsTalk
> Subject: [mems-talk] Etching Al2O3
> Dear mems-workers,
>
> How can I etch easily Al2O3?
>
> -Sampo Tuukkanen

Al2O3 etch rates vary a lot with deposition conditions and crystal structure.

For a sapphire wafer (crystalline Al2O3),
we tried many etchants, including H2SO4 + H3PO4 at 160 C.
None worked very well.

For electron-beam evaporated and for ion-beam-sputtered Al2O3, the samples
etched in
almost everything commonly used in MEMS: silicon isotropic etchant, KOH,
5:1 BHF, Type A aluminum etchant, and piranha.

        --Kirt Williams Agilent Technologies