Study On Fabrications And Structural Characteristics Of The Ultrathin SiO_xN_y Films

SiO_xN_y ultra thin films were grown by thermal nitridation with NiO and NH₃ used as the react gas respectively. The effect of surface orientation, nitridation temperature, nitridation time and reactive gas on the SiO_xN_y films was studied by the α -step equipment. The growth mechanism of SiO_xN_y was discussed qualitatively. The dependence of nitrogen content in SiO_xN_y films on nitridation conditions was investigated by X-ray spectrograph (XPS). The bonding mode of N with SiO₂ in the films was also analyzed. The MOS structure was prepared with as-grown SiO_xN_y film as the gate dielectric, and its electrical properties such as dielectric content, breakdown field and leakage current were investigated by the C-V method. The results show that the thickness and N content of SiO_xN_y films were directly influenced by the substrate orientation and the technical parameters. The bonding mode of N with SiO₂ in SiO_xN_y films varies with different thermal nitridation flow. Moreover, SiO_xN_y dielectric performed better compared with the breakdown field of the SiO₂ dielectric. Incorporation of H would affect the leakage characteristic of SiO_xN_y films grown in NH3, this can be improved by annealing in H-free condition.