Hi, Thank you for the advice. For Brad's question, I do not see noticeable rounding of the PR (using stylus profiler). I am going to fabrication more samples to get a better idea of the rounding. I will try both of your advices to solve this problem. Could someone throw light on where does these bubbles come from? They appear when I bake the second PR layer after exposure if the hard bake for the first PR layer is not long enough. Thank you. Sincerely Crayon Fu University of Virginia