Hi Daniel

Have you considered a thicker resist like the AZ9260. I know with
careful lithography you should be able to get 10x10um feature for
about 20um thick resist.

Best
Leo

On Tue, Feb 3, 2009 at 10:45 AM, James Paul Grant
 wrote:
> Thanks Daniel for your thoughts.
>
> Unfortunately I require an anisotropic etch and as i'm sure you know wet
> etching using HF acid or HF vapour is very isotropic. In any case I'd have
> great difficulty attempting to set-up an HF vapour etch set-up in our
> cleanroom at Glasgow. COSHH forms galore!
>
> My main problem is the selectivity of whatever etch I use versus my AZ4562
> photoresist. At present I can only achieve around 1:1 even for low etch
> rates of ~ 30 nm/min.
>
> I could use a metal mask but here at Glasgow we are not allowed to put any
> substrates with metal on them into the RIE machines.
>
> I've looked into the advanced oxide etch by STS. This looks promising for my
> needs, I just have to convince people here at the university that it's worth
> sending our CMOS chip there to get the 10 um silicon dioxide etched!
>

Xiaoguang "Leo" Liu
Birck Nanotechnology Center,
Purdue University,
1205 W.State Street, West Lafayette, IN, 47906 USA
liu79@purdue.edu