Dear all, I'm working on etch SiO2 by Ar ion-beam. The etch deep is about 1 micron. The wall of micro-structure isn't steep even if the sample is titled. Can anybody give me some advise how to improve it? Any information will be appreciated. Best regard Liu Gang National Synchrotron Radiation Lab Univ. of Sci.& Technol. of China Hefei 230029 P. R. China E-mail: liugang@ustc.edu.cn