Molecular volume and polarizability in the amorphous dielectric Zr_0.2 Sn_0.2Ti_0.6O₂

Abstract

The dielectric constant of a material is strongly dependent on both the polarizability and the density of the material through the Clausius Mossotti equation. While the atomic polarizability depends on the stoichiometry of the constituent atoms, the molecular polarizability is a function of the atoms’ short range bonding structure and hence can be strongly dependent on processing conditions. Since the density of the material also depends on the thermally activated diffusivity of atoms during processing, varying the processing temperatures has an effect on both the molecular polarizability and the density. The dielectric constant of Zr_0.2 Sn_0.2Ti_0.6O₂ is shown to be a strong function of the substrate temperature during sputter deposition with the highest value ε~55 at 200 °C and lower values at both higher and lower process temperatures. We have investigated the bonding structure and density of the oxide dielectric deposited at a variety of substrate temperatures in order to elucidate the relative effects of each.