High-permittivity metal-insulator-metal capacitors with TiO2 rutile dielectric and RuO2 bottom electrode

Abstract

We describe properties of MIM capacitor structures with the RuO2 bottom electrode, TiO2 dielectric film and various top electrodes. The TiO2 films were grown by atomic layer deposition (ALD) at temperature 425 °C on metal organic chemical vapour deposited (MOCVD) RuO2 bottom electrodes grown at 300 °C. Due to local epitaxial growth on the RuO2 rutile structure, TiO2 films with the permittivity 135 and equivalent oxide thickness 0.58 nm were obtained. Capacitance density as high as 60 fF/μm2 was achieved. Au and Ni films for top electrodes were prepared by evaporation at room temperature. RuO2 films for top electrodes were grown by MOCVD. Strong effect of top electrode material on capacitance and leakage currents was observed. In addition, the stacks with TiO2 dielectric were found to be very sensitive to oxygen post-deposition treatment.