I suggest you back lap/thin the wafer to 125 or 200 micron to start. Even
than the etch time is plenty long for a low cost product.
ELume has devised a proprietary small via <5 micron etch process, for
silicon as well as glass wafers unfortunately I cannot share at this time.
Good luck
Walter
www.elume.com

-----Original Message-----
From: Pradeep Dixit [mailto:pradeep.ntu@gmail.com]
Sent: Monday, April 25, 2005 7:20 PM
To: General MEMS discussion
Subject: [mems-talk] Through Hole etching of evry deep holes - Aspect ratio-
25-30

Dear All,

I need to etch through holes of very fine diameter (15,20,25,30 and 35
microns) in 450 um thick Silicon wafer. I am using 10 um thick AZ9260
photoresist as mask.

Standard bosch process is used. SF6- 130 sccm, C4F8-100 sccm, Platen
power - 150 W. After etching a long time, i could not etch them
completly. We have STS DRIE machine

Anyone would like to help me in this matter. What will be the optimum
parameters for though hole etching of very deep and narrow holes.

Thanks in advance.

Pradeep Dixit
Research Student,
NTU Singapore - 639669