Mikael,

           There are far better chemistries for adhesion for SU8 than
HMDS.  In fact I do not think HMDS has any effect on SU8 chemistry.
When I get to work on Monday I will discuss with our senior process
engineer Ken Sautter and send some suggestions for better chemistry and
treatment.

Bill Moffat

________________________________

From: mems-talk-bounces+bmoffat=3Dyieldengineering.com@memsnet.org on =
behalf of Mikael Evander
Sent: Fri 12/10/2010 7:38 PM
To: General MEMS discussion
Subject: [mems-talk] SU-8 3000 vs 2000 adhesion

Hi all!

I was wondering if anyone has some kind of input regarding how much
better the adhesion of SU-8 3000 is compared to the 2000 formulation.
I'm trying to make a 10- 20 um wide, 5 um high and up to 10 mm long
"barrier"on a glass wafer. I did my first tests with SU-8 2005 this week
and noticed that the adhesion was terrible. Very few of the barriers
remained intact and after dicing the wafers most of them were gone. My
wafers were piranha washed and HMDS-treated just before spinning the
SU-8.

I've been reading a bit and people usually recommend making sure that
the exposure time is enough, doing a low temperature PEB, ramping of the
hot plates, having a very clean and dehydrated wafer. Something that
also comes up a lot is to use SU-8 3000 instead as it is supposed to
have increased adhesion. My question is if anyone can comment on how
well the 3000 formulation seems to adhere to glass substrates. I need
the structure to remain intact as it will be a mechanical part of a
microfluidic device.

Many thanks and have a great weekend!

/Mikael