The Study on Preparing Methods of Porous Silicon Used in MEMS

Porous silicon was prepared by chemical etching, single-cell electrochemical etching and double-cell electrochemical etching. The shape of porous silicon prepared by above-mentioned methods was observed. The results show that the double-cell electrochemical etching is the best preparing method. The porous silicon obtained by this method has the smallest hole diameter (5~10 nm), good uniformity, and large depth (several hundred nm). Finally, studied are the etching time and current density of double-cell electrochemical etching which affect the etching speed of the porous silicon.