FERROELECTRIC LEAD ZIRCONATE TITANATE THIN-FILMS BY RADIO-FREQUENCY MAGNETRON SPUTTERING

Ferroelectric thin films of lanthanum modified lead zirconate titanate (PLZT) were deposited on platinum and fused quartz substrates by rf magnetron sputtering. Cold pressed powder was used as the target with excess PbO in the target composition. The PLZT films were deposited at different substrate temperatures and the thickness of the sputtered films were in the 1-2-mu-m range. The effect of post-deposition anneal on the structure and ferroelectric properties are discussed. The structure and composition of the films were determined by x-ray diffraction and energy dispersive x-ray analysis and found to be strongly dependent on the excess PbO content in the target, and on the deposition parameters. Films deposited on platinum have (111) or (110) orientation depending on the deposition temperature and the oxygen content in the sputter gas. Film Pb/(Zr + Ti) ratios were determined from energy dispersive x-ray spectra as a function of the sputtering geometry. Electrical properties were evaluated in terms of the dielectric constant, K, from capacitance measurements. Ferroelectric hysteresis characteristics were measured using a modified Sawyer-Tower circuit. The values of the remanent polarization, P(r), was in the range 5-15-mu-C/cm2 and the coercive field, E(c), between 17 and 35 kV/cm depending on the process parameters.