Low temperature nitrogen incorporation method for enhanced electrical properties in hafnia based gate dielectrics

A low temperature method (∼400 °C) for nitrogen incorporation in hafnia based dielectrics has been developed for future gate dielectric applications. Hf metal films were deposited on Si substrates in ammonia ambient and were subsequently oxidized under ultraviolet illumination. Using this method, an interfacial layer comprising Hf-Si-O-N bonding was formed at the hafnia-Si interface, which led to a substantial enhancement in the overall dielectric properties of the film. An equivalent oxide thickness of 11.5 Å and leakage current densities lower than 10-4 A cm2 at a gate bias of -1 V were achieved by this approach.