Hi,
I have been trying to put two layers of SU-8 on to a silicon wafer.

Cleaning of wafer includes rinsing in ethanol and then with DI water
followed by heating oven at 120 for about an hour.

I then plasma treated(o2) the wafer to improve the adherence of SU-8
to the wafer.

I then exposed it and finally developed it after baking it.

Now to lay the second layer of SU-8, I plasma treated the developed
wafer and then spun coated this wafer with SU-8 and then followed it
by Soft bake followed by exposure to UV and then baking it and finally
developing it.

When I cast PDMS to it, a part of the second layer came with the PDMS
after baking. Could anyone of you let me how to over come this
problem.

Thanks for all the help..

Cheers,
Vishwa