Hello,
I suggest you try an adhesive plastic foil, which is typically put on using
heat and pressure.  This product is often times used on the wafer prior to
backside thin down or prior to wafer sawing.  Good luck.


-----Original Message-----
From: JARED_LERA/electronics_singlekh2_kihung_grp0@gp_man

To: MEMS@ISI.EDU 
Date: Friday, November 27, 1998 8:55 PM
Subject: Defects due to photo patterning


>Dear colleagues:
>
> I am having a problem with making SiN membranes. When I pattern the
backside of the
>wafer the SiN coating on the front side gets all scratched up due to the
chucking and
>
>handling used in our photo lithography process. These scrathes then cause
our membranes
>to shatter when the SiN layer is exposed after the silicon is all etched
away. I have
>tried to place a thick oxide layer (2 microns) over the SiN to protect it
during the
>back side patterning. But still many defects appear. Is there any kind of
chucking machine
>
>that protects the side which is being handled?
>
>
>Thanks in advance for you help,
>
>
>Jared Lera
>Semiconductor R&D
>Samsung Electronics
>
>