XPS analysis of RTP formed ultrathin-gate oxynitride via low energy nitrogen implantation

Segregation of nitrogen to the surface was performed on nitrogen ion-implant (N-I/I) wafers under nitrogen gas. An ultrathin oxynitride layer ranging in thickness from 4 to 8.5 Å is the result of the segregation. Oxidation of nitrogen ion-implanted wafers, where the nitrogen is segregated beforehand and nitrogen ion-implanted wafers with no segregation prior to oxidation, is the focus of this study. The formation mechanism, the chemical composition and the physical thickness of the oxynitride films were studied by X-ray photoelectron spectroscopy (XPS). An oxynitride film consisting of two layers resulted from simultaneous segregation and oxidation. The outcome is a nitrogen rich interface and an oxygen dominant surface. In the case of nitrogen segregation prior to oxidation, the nitrogen atoms in the oxynitride film are uniformly distributed throughout the film in the form of SiO _xN_y