Rutile-structured TiO2 and Al-doped TiO2 dielectric thin films were grown on a sputtered Ru electrode by atomic layer deposition (ALD) using O-2- or N2O-plasma oxidants. The O-2-plasma-based ALD process produced films with a similar growth rate and electrical performance to those deposited using the O-3-oxidant-based ALD process, which has been reported previously [S. K. Kim , Appl. Phys. Lett., 85, 4112 (2004); S. K. Kim , Chem. Mater., 20, 3723 (2008)]. In contrast, the N2O-plasma-based ALD process resulted in a 1.8 times higher growth rate than that of the O-3-oxidant-based ALD process with identical electrical performance. Denser and uniform oxidation of Ru is essential for achieving pure rutile TiO2 films with a higher dielectric constant (up to 100) on Ru electrodes.