Hello Melissa,

Usually the adhesion of any resist is much better when the
samples are dry. So try putting them in an oven (we use 90degree)
for 15 min before applying the resist, this will remove the
condensed water from the surface.
HMDS usually also helps. (we use 10s 3000rpm, but  this should
not make much difference)

Good luck,

Karin

[email protected] wrote:

> Hi,
> Am trying to spin about 3-5 um of SU-8 onto a silicon wafer but was getting
> some problems of adhesion and the SU-8 came off during the development step. I
> read on this discussion group that HMDS was recommended to help with the
> adhesion of thicker layers of SU-8. I tried spinning HMDS ar 5000 rpm/30 sec
> before spin-coating the SU-8. However, during the pre-bake step (95 degrees
> for 2 min), the layer of SU-8 shrunk from the edges of the wafer. What is the
> reason for this and how can I prevent it if I want to use HMDS to aid SU-8
> adhesion? Thanking you in advance.
>
> Regards,
> Melissa
>
--
Dipl.-Ing. Karin Buchholz

Walter Schottky Institut
Technische Universitaet Muenchen