You can etch through the wafer with a crystallographic etch, such as KOH
or TMAH, which will result in sidewalls with ~55 degree inclination on a
<100> wafer.  Or you can etch through the wafer with ~vertical sidewalls
using RIE, e.g. Bosch Etch.  The laser approach is probably
unnecessarily expensive.  The wafer is normally grounded during RIE.
Grounding also might help if you hit the wafer with lightening:)

Roger Shile

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Jeff chen
Sent: Monday, April 03, 2006 1:17 PM
To: [email protected]
Subject: [mems-talk] Is there any way to etch a hole through on
siliconwafer?

Hi,

I am working on a project which needs to etch a hole through the
silicon wafer (525 micron thick). The hole diameter is around 50
micron.
Does anyone have experience to do that?
Is there any way to do that? Etching? Laser excimer? or grounding
technology?