We avoid wet chemistry when at all possible.
The plasma chemistries we use for this are either SF6, at low power,
high pressure, and high flows, which works reasonably well - but will
slightely etch oxides and resist (somewhere betwen 20 and 50:1,
depending on the settings), and have a down vs undercut rate of
something like 2:1 at best.

But what works much better is XeF2 systems - you can get almost zero
oxide and resist etch. Contact Xactix at xactix.com. Its a bit slower
etch rate, but more like 1:1 down vs undercut.

Xuzhengyi wrote:
>
> Dear all:
>
> I am now doing an experiment which need to etch the silicon without attacking
Al. The alkaline etchants that we usually adopted in MEMS, TMAH and KOH, could
not satisfy the requirement. I heard that some organic material can do this job,
can anyone here provide me the information? Or advise me other effective
solutions? Anything you provided will be highly appreciated!
>
> Thanks
>
> Daniel
>
> ************************************************************
> Daniel Xu (Xu zhengyi)
> ------------------------------------------------------------
> Ph.D candidate
> State Key Laboratories of Transducer Technology
> Shanghai Institute of Microsystem & Information Technology
> Chinese Academy of Sciences
> 865 Changning Road
> Shanghai 200050
> China
> ------------------------------------------------------------
> Tel: 86-21-62511070 ext. 8607
> FAX: 86-21-62513510
> email:[email protected]
> ************************************************************
> _______________________________________________
> [email protected] mailing list: to unsubscribe or change your list
> options, visit http://fab.mems-exchange.org/mailman/listinfo/mems-talk
> Hosted by the MEMS Exchange, providers of MEMS processing services.
> Visit us at http://www.mems-exchange.org/

--
Tom Rust
Nanochip Inc
Box 13249
Oakland, CA 94661
(510) 339-6263
(510) 339-9636 FAX
(510) 912-4662 cell
http://www.nanochip.com