We have also faced with a similar problem. After a wafer-level release and
on-wafer measurements, we have decided to dice some devices from those
wafers. We tried the following and it worked:
Coat the wafer with photoresist. Dispense 10-15 ml of photoresist (s1828)
and wait enough that it covers the whole wafer surface. Do not spin the
photoresist if any blank region is still present on the wafer. If there is a
blank region on the wafer, dispense more photoresist. Then spin the wafer at
1000 rpm with a low acceleration to 1000 rpm (in order not to break the
structures due to photoresist flow). Softbake at 100 C on the plate for 5
min. Dice the wafer. and release the structures again.
If you do not have so many wafers and if you do not want to process a new
wafer at the moment, this approach may serve you.
Regards,

Kagan TOPALLI
Research Assistant (Ph.D Candidate)
MEMS-VLSI and EMT Group
Middle East Technical University
Dept. of Electrical & Electronics Eng.
TR-06531 Ankara Turkey
Phone: +90 312 210 44 09 or +90 312 210 45 26
Fax: +90 312 210 23 04
http://www.mems.eee.metu.edu.tr/
http://www.eee.metu.edu.tr/~emt/

----- Original Message -----
From: "D. Zhou" 
To: "MEMS_BBS" 
Sent: Monday, September 04, 2006 5:39 PM
Subject: [mems-talk] Cutting chips with fragile free-standing devices
intosmall pieces


> Dear all,
>
> I am fabricating some free-standing MEMs devices based on SOI wafer. Now I
> need to cut the chips into individul devices to do some measurements. The
> problem is that the structure is so fragile that when cutting it using
> scriber and breaking it with hands the whole structure collapses. Could
> anyone who has been faced with the same problem please give me any
> suggestions?