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

Abstract

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 degreesC. 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 O-2 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. (C) 2001 American Vacuum Society.