Improving the microstructure and properties of PZT thin films via annealing prepared by RF magnetron sputtering using Pb(Zr0.52Ti0.48)O3 target

Abstract

PZT thin films are one of the most effective materials attractive for MEMs applications. In this research, high-quality PZT thin films were deposited on (111)Pt/Ti/SiO2/(100)Si substrates by RF magnetron sputtering from a Pb(Zr0.52Ti0.48)O3 ceramic target. The sputtered PZT films with deposition times of 90 min–180 min were annealed at different temperatures; 550°C-700 °C. The results indicated that the film's crystallinity, density, and morphology were affected by the sputtering time and the annealing conditions due to grain growth. Post-annealing improved the microstructure and properties of PZT thin films. The increase in annealing temperatures virtually caused the decrease of PZT thin-film thickness. Densification and PZT grain size were found to increase with increasing annealing temperatures. The XRD and SEM results demonstrated that the PZT thin films were well-crystallized and contained a uniform grain distribution. With sputtered time of 90 min, 120 min, 150 min, and 180 min, the thickness of PZT thin films were 168 nm, 228 nm, 266 nm, and 275 nm, respectively. WDS results showed that the atomic percentages of zirconium content decreased by increasing annealing temperature. At the 180 min-sputtered time, the remaining lead content after annealing temperatures of 550°C–700 °C showed an estimated 1.0 at%. Increased annealing temperatures affected significantly lead loss due to volatilization. The surface roughness was confirmed by AFM analysis of the proposed systems. The roughness values of films increased from 1.28 nm to 4.25 nm with increasing annealing temperature. The dielectric functions (ε1) and (ε2) of sputtered PZT thin films at different annealed temperature and different thicknessess were analyzed by Spectroscopic Ellipsometry (SE). The (ε1) and (ε2) of as-deposited PZT thin film showed different dispersion shapes, and (ε2) amplitude was shifted to the lower photon energy in comparison with annealed PZT thin films, which can correspond to differences in the crystal structure.