Effects of in-plane compressive stress on electrical properties of (Ba,Sr)TiO3 thin film capacitors prepared by on- and off-axis rf magnetron sputtering

Abstract

This study investigated the structural and electrical properties of (Ba,Sr)TiO3 (BST) thin film capacitors with thicknesses ranging from 18 to 215 nm, which were prepared by on- and off-axis rf magnetron sputtering technique on Pt/SiO2/Si substrates. The deposition rate and cation composition ratios of the films were controlled to be the same regardless of the sputtering geometry. All the films show elongations in the out-of-plane lattice spacing, suggesting the presence of compressive stress with a smaller value by on-axis sputtering than by the off-axis system. There was no thickness dependence of the strain in the polycrystalline BST films. The BST films deposited using the on-axis system showed a higher bulk dielectric constant with a higher interfacial capacitance and a lower leakage current level than the films produced by the off-axis system. The strain effect was proposed to explain the correlations between the structural and electrical properties.