Preparation of Thin BaTiO3 Films by dc Diode Sputtering

Abstract

Direct current diode sputtering of reduced BaTiO₃ ceramic has been applied to the preparation of thin BaTiO₃ films. Sputtering was carried out over a range of apparent sputtering rates of ∼500–1200 mg/Ah in atmospheres of argon and air. As the substrate, Pt sheet and fused quartz were principally used. Grain size of the deposited film was ∼1000 Å for the Pt substrate at 400°C. The lattice constants were in good agreement with those of ordinary BaTiO₃ when the Pt substrate was kept at a temperature above 1000°C, although they were slightly larger for substrates below 900°C. Measurements of optical density and observations of electron micrographs indicated that the sputter‐deposited films have more favorable properties of transparency, uniformity, and crystallization than vacuum‐evaporated films. The film prepared on a Pt substrate at 1000°C in an air atmosphere had a dielectric constant of 1700 and dissipation factor of 1.8% without post‐deposition treatment. However, the remanent polarization was very small and the temperature dependence of the dielectric constant was slight.