We have investigated the structural and electrical properties of ZrxTiyO2 films grown on a RuO2 substrate by atomic layer deposition (ALD) with a variation of the ALD cycle ratio of ZrO2/[ZrO2+TiO2], RZr/[Zr+Ti]. TiO2 films (15 nm thick) grown at 225 degrees C using water as an oxygen source showed a rutile structure and a dielectric constant of 90 after postannealing at 600 degrees C. With an increase of RZr/[Zr+Ti] to 0.50, the leakage current density of 15 nm thick ZrxTiyO2 films grown at 225 degrees C was improved to be 1.2x10(-6) A/cm(2), but the dielectric constant decreased to 20. This is attributed to the destruction of rutile TiO2 structures into amorphous ZrxTiyO2 phase by the increase of Zr content.