Li,

In principle this is how all HF vapor etching is performed. In the
equipment from Idonus (and other companies) the temperature is
well-controlled and the liquid HF is well-sealed from the user. Many
lab managers are not at all fond of having open beakers with HF
standing around on benches.

The substrate temperature is indeed critical. At low temperatures the
etch-rate will often be too fast and you might get condensation on
your substrate, leading to the same type of reactions as with liquid
HF (etching of metal, stiction etc.). Normally you want to perform HF
vapor etch at about 40 degrees.


On Fri, Apr 30, 2010 at 10:44 PM, Li. Zhang  wrote:
> Hi Karolina,
>
> Actually, I also plan to apply vapor phase HF etch for SiO2 release since I
> got device damaging problem with wet HF etching. Currently I'm still keeping
> with wet HF but working on different approaches. I heard from people, some
> flip over SOI wafer upside down and hang it over concentrated HF. They use
> this as alternative approach for vapor phase HF etching.


/Sven Holmström, Koc University, Istanbul, Optical Microsystems
Laboratory (http://mems.ku.edu.tr/)

Work phone: +90 212 338 1 772
Mobile phone:+90 5383365642
FAX: +90 212 338 1548 (Please note my name)
E-mail: sholmstrom@ku.edu.tr

Work address:
Koç University
Dept. of Electrical Engineering
Rumeli Feneri Yolu, Sariyer
34450, Istanbul-Turkey