Dear all, I'm using Oxford Plasma 100 to etch through silicon wafer. The masking material used in DRIE is hard baked AZP4620. I did checked the PR mask after hard bake with microscope, which shows smooth profile. But when I use it to get the wafter etched through, the sidewalls show light striation from top to the bottom. I know over-passivation will lead to striation on the sidewalls, but I'm sure my case is not. Over-passivation induced striation will not occure from the beginning. Somebody says that sidewall stiation formation depends on: 1. Masking material 2. Etch chemistry 3. Power regime I'm not sure what is wrong with my etch. Can anyone help me out from the bad situation? Thanks a lot! BR, YN WANG