Reactive ion etching of zinc oxide (ZnO) in SiCI<4 based plasmas

The reactive ion etching (RIE) of zinc oxide (ZnO) in a silicon tetrachloride (SiCl₄) based plasma has been studied. The etching rates have been found to increase by decreasing the chamber pressure, by adding argon (Ar) to SiCl₄ or by increasing the RIE power density. These observations suggest the importance of the presence of ion bombardment on the surface in the etching mechanism. The relatively high pressure and low bias voltage employed allow the use of standard photoresist as masking material. Moreover, the achieved maximum etching rate, without damaging the photoresist, has been found to be 26.7 nm/min. Electrodes in the ZnO have been patterned as a demonstration for possible implementation in piezoelectric sensing elements for MEMS resonators.