Good luck. I've tried a lot of etchants, but sapphire is the most inert
material I've come across.
I found an etching reference that says that 1 H2SO4 : 1 H3PO4, 160 deg C
(which is really hot) should work, but it barely etched (< 0.3 nm/min) after
an hour.
You might be better off trying to mill it, but it wears diamond out fast as
well.
    --Kirt Williams

----- Original Message -----
From: "Nitin Shukla" 
To: 
Sent: Thursday, September 13, 2007 7:32 AM
Subject: [mems-talk] Sapphire etch!


> Hi,
> I am looking for a way to selectively etch sapphire (but not Si).
> Thanks,
> Nitin
>