Properties of TiO"2-based capacitors with RuO"2 bottom electrode were examined. It is shown that post-deposition room temperature plasma treatment and oxygen annealing at 300^oC significantly reduces amount of impurities in the TiO"2 layer. Leakage current density of the capacitors is suppressed due to improvement of oxygen stoichiometry and increase of Schottky barrier height at the TiO"2-dielectric/metal electrode interface after post-deposition processing. Leakage current density below 10^-^7A/cm^2 was achieved for capacitor with equivalent oxide thickness of 0.58nm.