Electrical characteristics of (Pb,Sr)TiO3 thin films for ultra-large-scale-integrated dynamic random access memory capacitors prepared by liquid-source misted chemical deposition

For the first time, the physical and electrical properties of lead–strontium–titanate (PST) thin films were prepared by liquid-source misted chemical deposition, and are reported. PST thin films were deposited on a platinum-coated Si wafer. Pb acetate, Sr acetate, and Ti isoproxide were used as metallic precursors. These were dissolved in 2-methoxyethnol. A fine mist of metallic precursor solution was carried into a deposition chamber by Ar carrier gas. The crystallization of PST thin film was achieved by heat treatment above 500 °C. The composition and depth profile of PST film, measured by wavelength-dispersive spectroscopy and Auger electron spectroscopy, were uniform. The dielectric constant and dielectric loss of Pb0.36Sr0.64TiO3 films of 80 nm thickness were 376 (equivalent oxide thickness: 0.83 nm) and 0.05, respectively. The electrical properties were improved by postheat treatment under O2 ambient gas after a top electrode Pt was deposited on a PST thin film. It is concluded that PST can be used as a high-capacity material for ultra-large-scale-integrated dynamic random access capacitors.