Deposition of Pb(Zr_xTi_1-x)O₃ thin films by pulsed laser ablation for MEMS application

Pb (Zr_xTi_1-x) O₃ films were prepared by pulsed laser ablation on Pt/Ti/SiO₂/Si substrates at room temperature and were crystallized by subsequent annealing. The effect of the Pb content and Zr/Ti ratio in the target on crystalline structure and electrical properties of Pb (Zr_xTi_1-x) O₃ films was investigated. Crystalline phases and structure in the PZT films were investigated by X-ray diffraction analysis (XRD). The microstructure and composition of the films were studied by scanning electron microscopy (SEM) and electron probe microanalysis (EPMA), respectively. It was found that the addition of 20 wt% excess PbO to the PZT target is necessary to obtain a single perovskite phase. X-ray diffraction analysis results show that the film fabricated from the target with Zr/Ti ratio of 30/70 crystallizes in the tetragonal phase, while the films fabricated from the targets with Zr/Ti ratios of 70/30, 58/42, 52/48, 45/55 crystallize in the rhombohedral phase. The films derived from the target with Zr/Ti ratio of 45/55 and with 20 wt% excess PbO exhibited better electric properties. The remanent polarization and coercive field of the film were 31.28 μC/cm² and 45.29 kV/cm, while the dielectric constant and loss value measured at 1 kHz were approximately 1069 and 0.08, respectively. The results demonstrate that a few micrometers thick PZT thin films derived by laser ablation for use in micro actuators is possible.