Development and Fabrication of Thin-Film BatiO₃Capacitors using Radio-Frequency Magnetron Sputtering

BaTiO3 thin films were deposited by radio-frequency magnetron sputtering. The electrical and dielectric properties of the films were investigated as a function of substrate temperature and sputtering gas. The performance of the thin-film capacitors was studied as a function of the capacitor structure and elect rode materials. The film formed at room temperature, with Ar + O₂gas, showed an amorphous structure and had very good insulating properties. The films formed at high temperature (700 °C) had a polycrystalline structure, yielded a high dielectric constant up to 330, and lead to a large dc leakage current. By using Ar + H₂ 1O₂ as the sputtering gas, the leakage current was reduced from 6.2 X 10⁶ to 2.5 X 10~⁹ A/cm² for the amorphous film, and from 7.7X 10 ¹ to 7.7X10^-7 A/cm² at 4.0 V for the polycrystal films, respectively. Single and double layer capacitors were developed and fabricated using the above amorphous and polycrystalline films with Pd and RuO₂ as the electrodes. The temperature dependence of the capacitance was found to be very small even at the Curie temperature. This can be explained by the modifications of composition and microstructure.