Reactive sputtering deposition of low temperature tantalum suboxide thin films

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Abstract
A relatively simple direct current sputtering deposition scheme has been employed to deposit 1000 Å tantalum oxide thin films at low temperature. At ≂190 °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 (∼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 TaOx where x≂1.5. These low temperature, high dielectric constant thin films have potential applications as decoupling capacitors in very high speed electronic circuits and packaging.