REACTIVE SPUTTERING DEPOSITION OF LOW-TEMPERATURE TANTALUM SUBOXIDE THIN-FILMS

A relatively simple direct current sputtering deposition scheme has been employed to deposit 1000 angstrom tantalum oxide thin films at low temperature. At congruent-to 190-degrees-C substrate temperature, without further annealing, tantalum oxide films with a dielectric constant of 21-22 and a leakage current density as low as 10 nA/cm2 at 0.5 MV/cm electrical field strength (approximately 5 V of applied voltage) are obtained. These properties are achieved over a wide range of O2/Ar ratios when the total flow rate is kept constant. XPS measurements reveal that these films are nonstoichiometric with a composition of TaO(x) where x congruent-to 1.5. These low temperature, high dielectric constant thin films have potential applications as decoupling capacitors in very high speed electronic circuits and packaging.