Hello,
As a follow up to the earlier posting, I would like to add a couple
more expts and observations that I performed today. I desperately need
some help as I am not getting adhesion

Recipe followed
1) Bare Silicon wafer - Rinse with Ethanol, followed by DI water,
Dried with N2 and then plasma treated with oxygen (1 Torr, 22w, 1
min). When I don't plasma treat the wafer, then the SU 8 moves towards
the center of the wafer during soft bake

2) First Layer spin coat - ramp to 500 at 100rmp/s and hold there for
10 sec, then ramp to 1500 rpm at 300rmp/s and hold for 30 sec. I use
SU 8 -2025 and this rmp is used to fetch 60um thick coating

3) SEB -
4) Exposure - I use a film which is attached to a glass by means of
scotch tape. I expose it according to the application notes provided
by microchem
5) PEB
6)Second layer spin coat - at 3000 rpm to yield 30 um
7)SEB
8) Exposure
9)PEB
10) develop

The SEB and PEB are done according to individual layers.

The mold looks ok. When I pour PDMS( mixed in 10:1 and degassed for 1
hr) and heat on hot plate at 100 degrees for 12 mins, and then peel,
the second layer comes off.

So, I tried to create on the second layer on the wafer and the result
is the same. The second layer is an array of rectangular structures
whose dimensions are 50um x 2.5mm x 30um.

When I was going thru the archives, I did see that heating the wafer
before spinning SU-8 helps. Should I do that in spite of plasma
treating the wafer?

I need some help as have no idea how to address this issue.

Thanks a lot in advance.

Vishwa