Fabrication of Smart Material PZT thin Films by RF Magnetron Sputtering, Method in Micro Actuators

Abstract

PZT piezoelectric thin films are promising candidates for use as microactuators or microsensors in MEMS (Micro Electro Mechanical Systems) or NEMS (Nano Electro Mechanical Systems) because of their quick response to electrical stimuli. In this research, the RF magnetron sputtering method is used to deposit PZT thin films. Sputtering conditions are proposed that control the crystalline plane (111) of perovskite structure for PZT in order to influence the piezoelectric constant. The substrate angle and temperature, Ar/O2 pressure and flow rate were investigated by the heuristic and experimental design methods to optimize the PZT perovskite crystal thin film. The substrate temperature was the most important factor that affected the piezoelectric constant. The crystalline structure, surface topography and piezoelectric constant of the deposited PZT were observed by X-ray diffraction structural analysis, atomic force microscope and piezoelectric constant evaluation equipment. PZT thin films with only perovskite structure were obtained and PZT (110) was mostly dominated. With increased substrate temperature, PZT (111) was grown, and the piezoelectric property improved. The measured elastic modulus of 70 GPa for the deposited PZT was in good agreement with the quoted value for commercial based bulk PZT. We obtained a pizoelectric constant of d31=-28 pm/V, and produced a high performance bimorph actuator.