Preparation of composition-controlled silicon oxynitride films by sputtering; deposition mechanism,and optical and surface properties

Silicon oxynitride films have been grown on silicon by current-controlled reactive sputtering. The content of oxygen in the films could be well controlled by regulating the sputtering current under the reactive gas of Ar+ N₂ with an oxygen content of around 3%. The atomic ratio of oxygen to nitrogen in the silicon oxynitride film became larger with increasing sputtering current. It has been found that electron irradiation of the silicon substrate induces adsorption of oxygen and nitrogen. The degree of oxygen adsorption was about ten times larger than that of nitrogen. This phenomenon is a key mechanism in controlling the film composition. The adsorptive mechanism might be explained by the phenomenon of surface activation by the electron bombardment. Utilizing this technique, wettability by germanium of silicon oxynitride films could be controlled by varying their oxygen and nitrogen contents. A better wetting condition was obtained from films with large atomic ratio of nitrogen to oxygen in the silicon oxynitride film.