Hi,

We have been struggling with the adhesion of SU-8 on NOA61 (Norland Optical
Adhesive a UV curable epoxy). We are trying to make optical waveguide in
SU-8 with NOA61 as the cladding layer. We tried using HMDS to promote
adhesion between the two polymers but so far unsuccessful.

In a typical experiment, we spin NOA61 on clean Si wafer, and UV expose it
to harden the epoxy. We then spin SU-8 on this. Without adhesion promoter,
SU-8 simply flies off. With HMDS, some SU-8 sticks, though the thickness is
far less than what we should get at that spin speed.

Any help in this regard will be greatly appreciated. Thanks in advance.

Satyanarayan