Hi,

Yes, you can use TMAH for Si bulk etching. But be
aware that TMAH also etches Aluminum. You can reduce
Al etch rate by adding Silicon powder, dissolving some
silicon in TMAH before starting etching your chips,
.....

If you use lower concentrations of TMAH to get faster
etch rates, you will get a rough final silicon
surface.

Regarding the safety, TMAH is a carcinogen material
and proper protection and ventilation is necessary.

You have to develop your own recipe to get desired Si
etch rate, Al protection and surface smoothness.

KOH can also be used but I don't have experince with
that.

You can find details in following references:

* Erno Hilbrand Klassen, MICROMACHINED INSTRUMENTATION
SYSTEMS, PhD Thesis, DEPARTMENT OF ELECTRICAL
ENGINEERING, STANFORD UNIVERSITY, May 1996.

* Nim H. Tea, Veljko Milanovic, Christian A. Zincke,
John S. Suehle, Michael Gaitan, Mona E. Zaghloul, and
Jon Geist, “Hybrid postprocessing etching for
CMOS-compatible MEMS,” Journal of
Microelectromechnical Systems, vol. 6, no. 4, pp. 363-
372, December 1997.

* H Seidel, L. Csepregi, A. Heuberger, H. Baumgaertel,
"Anisotropic etching of crystalline silicon in
alkaline solutions," Journal of the Electrochemical
Soc., vol. 137, no. 11, pp. 3612-3626, 1990.

* K. E. Bean, “Anisotropic etching of silicon,” IEEE
Trans. Electron Devices, ED-25, pp. 1185-1193, 1975.

Good luck with your etching,

Alireza Mesgar
MASC student
Concordia University
Montreal, Quebec, Canada

--- Sri Punnamaraju  wrote:

> Dear MEMS community,
> Is TMAH compatible with a 1 micron, 2-metal process
> CMOS ASIC foundry? Can TMAH be used for wet etching?
> Are there any contamination and corrosion issues? If
> so, what are the safety/set up requirements? Is
> there
> any other CMOS compatible etchant for Si bulk
> anisotropic wet etching? Awaiting your valuable
> inputs.