Also you might want to try a combination of KOH and then use TMAH. Although KOH
is very aggressive and etches through Si very fast compared to TMAH.

-----Original Message-----
From: Kasman, Elina 
To: Andrea Mazzolari ; General MEMS discussion 
Sent: Mon, 10 Jul 2006 08:09:02 -0500
Subject: RE: [mems-talk] Etch through Si wafer with TMAH


Since TMAH is an anisotropic etchant of silicon, for (110) plan wafer
the etched walls will be perfectly vertical (the etch is much slower
against (111) plane and this will result in vertical walls). However,
this also means that your etch mask has to be alligned with the flat,
otherwise the etch will "correct" itself and find the (111) plane even
if it's not aligned with your mask. You will have some underetching, but
these will also be vertical.
500um is one long etch.

Elina Kasman
Process Development Engineer, R&D
Engis Corporation