[mems-talk] SU-8 Adhesion with SiO2

[Prakash Mukre]

Hi All,

I am trying to deposit SU-8 over thermal oxide. SU-8 is part of the final
device I am fabricating, so I want it to adhere to the substrate strongly.
But with my current recipe SU-8 delaminates after development. Following are
the some process specs I am following.

SU-8 2100 Thickness: 200-250um
Softbake: 15min @65C,  100min @95C.
UV Dose: I have tried 400mJ/cm2 to 1000mJ/cm2
Hard Bake: 5min @65C, 20min @ 95C.
Development time: 10-20min.

I have tried using primers like HMDS, P20. Also I have tried using Omicoat.
What could be the possible reason for this? or SU-8 does not adhere to
thermal oxide at all?

Thanks,
Prakash