A method of improving the electrical properties of high dielectric constant films by depositing an initial film and implanting oxygen ions to modify the film by decreasing the oxygen deficiency of the film while reducing or eliminating formation of an interfacial silicon dioxide layer. An initial high dielectric constant material is deposited over a silicon substrate by means of CVD, reactive sputtering or evaporation. Oxygen ions are preferably implanted using plasma ion immersion (PIII), although other methods are also provided. Following implantation the substrate is annealed to condition the high dielectric constant film.