Ilseok,

I etch holes all the way through a 4" Si-Wafer with TMAH. But unless the
etchtime takes quite long, I use 240um thick wafer. but I also did it with
550um thick ones. The etchrate is about 1um per minute. What kind of
information do you need?
-Andreas

-----Original Message-----
From: il-seok Son [mailto:[email protected]]
Sent: Thursday, March 06, 2003 4:32 PM
To: [email protected]
Subject: [mems-talk] Etch through Si wafer with TMAH


Dear users.

I have a question about TMAH etching.
Dual-doped TMAH ( 5% TMAH + Silicic acid + Ammonium persulfate) is widely
used because it is enable to etch Si without attacking Aluminum, in addition
to its CMOS compatibility. Many papers have been published regarding
TMAH/dual-doped TMAH.
However, I found that the Si was etched for a short duration (maybe less
then 2 hours) in most papers.

In order to etch through a 3" wafer with dual-doped TMAH, it needs at least
8 hours.
I wonder if there is anyone who etches a wafer through ( 3" or 4") with
TMAH/ dual-doped TMAH, with CMOS or any integrated circuit.

Any information would be very helpful.

Thank you very much.

__________________________________________________________
Il-seok  Son (Sunny)
Dept. of Electrical and Computer Engineering
University of Wisconsin - Madison, Sonic MEMS Lab
__________________________________________________________