Hi, all.
I am trying to make devices using two positive layers, the bottom one with
about 5 um thick positive resist (Shipley SPR series),and the top one with
about 20 um thick SJR 5740 (minimum feature of 3 um) using electroplating
technique.

But when I finished the plating with first PR layer mold, I noticed very
small cracks in the resist. Those cracks made problems after I applied SJR
5740 with seed layer on it. Such cracks got bigger and bigger so that they
made another problems (e.g. shorting metal lines) to the second
electroplated structures.

The reason I am using the 5 um positive PR is to get microstructures with
5um suspended gap and it is easy to prepare and remove. But since I have had
such cracks in the first PR layer during plating process at 55 oC, I am
wondering whether there are other good positive PRs or I need to use some
thick oxide layer (PSG or BPSG).
Please let me know any possible solutions.

Thanks in advance.

Best regards.

Daniel Sang-Won Park
Graduate Research Assistant