Highly insulative barium zirconate-titanate thin films prepared by rf magnetron sputtering for dynamic random access memory applications

Polycrystalline thin films of Ba(ZrxTi1−x)O3 with x=0–0.4 and a thickness of ∼180 nm were deposited on platinum-coated silicon substrates by rf magnetron sputtering at 500 °C. Ba-rich targets were used to prepare films of stoichiometric composition. The film having x=0.12 exhibited a satisfactory dielectric property of dielectric constant, k≊300, and dissipation factor, tan δ0.02, at frequencies from 103 to 106 Hz under ambient temperatures ranging from 20 to 180 °C. More importantly, the film showed a very stable and highly insulative characteristic against applied voltage. The leakage current density J increases only smoothly to a value less than 10−7 A/cm2 followed by an Ohmic relation of J=σE with σ=1.4×10−14 (Ω cm)−1 up to an extremely high electric field E of 5.6 MV/cm without any sign of abrupt increase of leakage current or electrical breakdown. Also, no time-dependent electric degradation was observed for the film subjected to an electric field as high as 5 MV/cm at room temperature up to 3600 s of measurement.