Oxynitridation of silicon using helicon-wave excited and inductively-coupled nitrogen plasma

Si was oxynitrized (and/or nitrized) in both helicon-wave-excited and inductively-coupled N-2 or N-2 + Ar mixed plasma. Fairly good capacitance-voltage (C-V) characteristics were obtained after post-thermal annealing at 400 degrees-500 degrees C for 30 min in nitrogen ambient. X-ray photoelectron spectroscopic (XPS) measurements showed that chemically stoichiometric Si oxynitride, Si-2 N-2 O, was uniformly formed throughout the whole film thickness at a flow-rate ratio of N-2 of 80% in a N-2 + Ar mixed plasma (N-2:Ar = 8:2). On the other hand, SiO2 was formed at the outer surface while Si-2 N2O was formed in the middle portion of the film and near the interface between the grown film and Si, when the flow-rate ratio of N-2 was less than about 80%. The growth rate and the degree of ''nitridation'' were maximum at flow-rate ratio of N-2 of 80%. The leakage current in the film was found to be mainly the Fowler-Nordheim-type tunneling current.