Surface and interface properties of ferroelectric BaTiO3 thin films on Si using RuO2 as an electrode

Abstract

Ferroelectric BaTiO₃ thin films were deposited on Si by rf magnetron sputtering. A conductive oxide, RuO₂, was used as the bottom electrode of the capacitors. The performance of the thin film capacitors was found to be a strong function of the surface and interface properties between ferroelectric BaTiO₃ and the bottom electrode. A suitable capacitor configuration must be used to preserve the bottom electrode, to enhance the dielectric constant, and to reduce the leakage current density of the films. BaTiO₃ thin film on the RuO₂/Si substrate, where the BaTiO₃ thin film has a bilayer structure of polycrystalline on microcrystalline, showed a dielectric constant of 125 at a frequency of 1 MHz, leakage current density of 10⁻⁶ A/cm² at a field intensity of 2.5 × 10⁵ V/cm, and a breakdown voltage above 10⁶ V/cm.