Characteristics of BaTiO₃ thin films on Si deposited by rf magnetron sputtering

Abstract

Thin films of BaTiO₃ were deposited on single-crystal Si using rf magentron sputtering. Different microstructures resulted from varying the substrate temperature during sputtering or from post-annealing after film deposition. High trap and surface state densities at the interface between BaTiO₃ and were found for the films deposited at room temperature even though such showed a relatively low leakage current and a high breakdown voltage. These surface states or traps, nevertheless, could be partially annealed out of the film a temperature around 450°C. High deposition temperatures above 600°C introduced unrecoverable surface states at the interface. BaTiO₃ thin films were deposited at a substrate temperature in the range 450-500°C gave the performance in terms of their electrical and interface properties. BaTiO₃ thin-film capacitors with a configuration of Au/BaTiO₃/p-Si/Al, fabricated with optimized BaTiO₃ thin-film deposition conditions, showed a value of the dielectric constant near 30, a leakage-current density as low as 10⁻⁷ A cm⁻² at a field intensity 2 × 10⁵ V cm⁻¹, a breakdown voltage above 10⁶ V cm⁻¹ and an interface density of around (4–6) × 10¹¹ eV⁻¹ cm⁻².