Hi, all, I am designing a structure (a PDMS film bridge over a trench). I need to make a trench and fill it with some material(PSG,SOG,SU-8???...), and then spin PDMS on it and pattern. the trench is 1000um*1000um and 30-40 microns in depth. Can anyone tell me which material is fine for filling a 40um-deep trench, and what are the steps. I also want to know whether there are some good ways to etch PDMS. does O2 plasma work? I found a paper that used scratching and lift-off, but i dont think the surface will be very smooth after scratching. I just searched on the internet/IEL, but failed to find good ways on it. Thanks a lot, Jianhua ---------------------------- jh.tong@utoronto.ca tongjh@student.dlut.edu.cn