Hello Ying Cai

If you are going to do a back grind then you might consider using xenon
difluoride to remove the rest. While it is slower than KOH it is selective to
almost everything. So you can protect the front of the wafer with a simple photo
resist coat or in most cases you could avoid a protective coating altogether.

If you want to try it please contact me. XACTIX is the leading supplier of XeF2
etching equipment world wide and we can run some samples in our demo lab.

Regards
David Springer
XACTIX, Inc.
2403 Sidney St
Suite 265
Pittsburgh, PA 15203
+1 412 381 3195
[email protected]
www.xactix.com


>>  To use KOH to etch through the handle wafer takes long time so you face
 >>  the
 >>  front side protection issue and uneven silicon etch issue. The better way
 >>  to
 >>  do this is to do backside grind, to the minimum thickness that you can
 >>  handle and then do KOH etch.

 >>  Hong Wu

 >>  -----Original Message-----
 >>  From: [email protected]
 >>  [mailto:[email protected]]On Behalf Of Ying Cai
 >>  Sent: Saturday, October 16, 2004 9:51 AM
 >>  To: [email protected]
 >>  Subject: [mems-talk] A question on SOI wafer


 >>  Hi, dear all,



 >>  Now I have a SOI wafer in hand.  I need to get the device layer only.
 >>  What
 >>  should I do to remove the handle layer and BOX?



 >>  One way to do is to use KOH to remove the handle layer first, then use HF
 >>  to
 >>  remove the BOX?  Is there any other process to do this?



 >>  Thank you very much.



 >>  Sincerely,



 >>  Ying Cai

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