Patterning PZT Thin Films using Reactive Ion Beam Etching for PiezoMEMS, RF MEMS Resonator and Filter Applications

Thin film PZT exhibits several advantages for fabricating PiezoMEMS, RF MEMS resonators and filters due to its high electromechanical coupling factors. However, patterning PZT thin films still remain as a challenge. Traditional patterning techniques like ICP/RIE results in poor selectivity to Pt electrode and photoresist mask, rough etched surface and redeposition on the sidewall (fencing). The sidewall redeposition results in leaks between the bottom and top electrodes. This paper reports the reactive ion beam etching (RIBE) of PZT with smooth surface, nearly vertical profile angle, no redeposition on the sidewall and high selectivity to Pt electrode and photoresist mask.