X-ray photoelectron spectroscopy and Auger spectroscopy studies of thin silicon nitride films thermally grown on silicon

Abstract

The composition of silicon nitride films obtained by rapid thermal nitridation of silicon in NH3 at 1000–1250 °C for 10–20 s was analyzed using x-ray photoelectron spectroscopy (XPS) and Auger spectroscopy. The films were 10–25 Å thick. The depth resolution of Auger sputter profiling was not sufficient to analyze these films. Instead, depth profiles were obtained by chemical etching techniques. XPS peak intensity profiles and analysis of XPS peak shapes indicated that oxygen contamination was incorporated within the film in a silicon oxynitride state. The concentration of oxygen was peaked at both the surface of the film and the substrate–film interface. Observed XPS peak shifts within the film are explained by the variation in oxygen content. A 10%–20% decrease in Dλ (product of density and electron escape depth) was detected near the interface. Despite the extreme thinness of these films, they were found to be resistant to room-temperature oxidation and to degradation from chemical cleaning techniques.