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!

Cheers

James


Daniel Drysdale wrote:
> Hi James, have you considered HF vapour etching? I know it is pretty useful
for SiO2 etching though I am unsure how your resist will react to the HF vapour.
There are a couple of companies that I know of that deal with this.. One based
at Livingston and also within Edinburgh University at their SMC building is
MEMSSTAR who do this kind of work. As I say, I am unsure of the reaction that
the vapour would have with the HF but its a possibility i guess.

Dr. James Paul Grant
Postdoctoral Research Associate
Microsystems Technology Group
76 Oakfield Avenue Room 3
University of Glasgow
Glasgow
Scotland
G12 8LS

Telephone: +44(0)141 330 3374