Structural and Electrical Characteristics of HfO₂ Film Deposited by RF Sputtering and Plasma Enhanced Atomic Layer Deposition

Abstract

We report the effect of annealing on the structural and electrical properties of thin HfO₂ film deposited on p <100> silicon substrate by RF sputtering and Plasma Enhanced Atomic Layer Deposition techniques (PEALD). Multiple angle ellipsometric analysis in the range 65–80° shows the variation of refractive index in the range of 1.9–2.6 for PEALD HfO₂ and 2.74–2.9 for sputtered HfO₂ annealed in the temperature range of 450–600 °C. Grazing incidence angle X-Ray diffraction result shows the orthorhombic film structure with <121> and <111> dominant peaks for the PEALD and sputtered HfO₂ film respectively. Electrical measurements on the MIS capacitor structure shows the positive flatband voltage of 1.7 V, leakage current of the order 10⁻¹¹–10⁻¹² A/cm² and the breakdown voltage of 36 V for PEALD deposited film at the annealing temperature of 500 °C. For the sputtered deposited film, at the same annealing temperature, the flatband voltage is 0.5 V and the leakage current density of the order 10⁻⁵–10⁻⁶ A/cm² with a breakdown voltage of 30 V has been observed.