Effect of a silicon nitride buffer layer on the electrical properties of tantalum pentoxide films

Ta2O5 films with a buffer layer of silicon nitride of various thicknesses were deposited on Si substrate by reactive sputtering and submitted to annealing at 700 °C in nitrogen atmosphere. The microstructure and the electrical properties of thin films were studied. It was found that with a buffer layer of silicon nitride the electrical properties of SixNy/Ta2O5 film can be improved than Ta2O5 film. When the thickness of the buffer layer was 3 nm, the SixNy/Ta2O5 film has the highest dielectric constant of 27.4 and the lowest leakage current density of 4.61 × 10−5 A/cm2 (at −1 V). For the SixNy (3 nm)/Ta2O5 film, the conduction mechanism of leakage current was also analyzed and showed four types of conduction mechanisms at different applied voltages.