Dielectric Characteristics of Hafnia Thin Films

Abstract

The dielectric characteristics of hafnia thin films deposited by the DC reactive magnetron sputtering of a Hf target in an Ar/O₂ gas mixture without heating the substrates have been studied. The permittivity, dielectric loss tangent, band gap, and leakage current density are obtained as functions of the oxygen content in an Ar/O₂ gas mixture upon film deposition. As is established, hafnia thin films with good dielectric characteristics are formed in a relatively wide range of oxygen concentrations (about 12–20% O₂). Without heating the substrates and subsequent annealing, the films possess permittivity ε = 17–22, a loss tangent of 0.03–0.05, and leakage currents density of 10⁻³ A/cm at E = 5 × 10⁵ V/cm; the optical band-gap width of the deposited films is found to be 5.7–5.8 eV.