Influence of Sputtering and Annealing Conditions on the Structure and Ferroelectric Properties of Pb(Zr,Ti)O3 Thin Films Prepared by RF Magnetron Sputtering

Abstract

Lead zirconate titanate (PZT) thin films were prepared on Pt/Ti/Corning 7059 glass substrates by RF magnetron sputtering using a Pb(Zr0.5,Ti0.5)O3 ceramic target. X-ray diffraction studies were performed on the films to optimize the sputtering pressure, O2/(Ar+O2) mixing ratio (OMR), annealing temperature and annealing time, to prepare the films in the perovskite phase. As-deposited amorphous film goes through an intermediate pyrochlore phase before crystallizing in the perovskite phase. Perovskite phase formation started at 625°C and annealing at 650°C for 2 h was found to be necessary for complete crystallization in the single perovskite phase. Perovskite phase formation was confirmed with the existence of a perovskite rosette structure by scanning electron micrograph (SEM). Energy dispersive X-ray (EDX) compositional analysis of as-deposited films showed Pb/(Zr+Ti) ≃ 1.1; a 10% deviation from the target stoichiometry. Ferroelectric and dielectric properties of the capacitor with thin platinum films as both electrodes were investigated in detail as functions of annealing temperature and annealing time. The marked improvement in the structural and electrical properties observed in the deposited film after annealing was mainly due to the crystal growth of small crystallites. The dielectric constant and loss tangent of the films annealed at 650°C for 2 h were 580 and 0.06, respectively. The films with 1.4 µm thickness that were annealed at 650°C showed a remanent polarization (Pr)=26 µC/cm2 and coercive field (Ec)=51 kV/cm.