[15p-P14-1~11] 13.3 Insulator technology

[15p-P14-1] Surface oxidation process of silicon-rich SiN films under humid environment

〇Tomoki Oku¹, Toshihiko Shiga¹, Masahiro Totsuka¹, Shinichi Takagi¹ (1.Mitsubishi Electric)

Keywords:Silicon nitride, Humid resistivity, Molecular orbital calculation

We applied the semi-empirical molecular orbital calculations to analyze the degradation of the humid resistance of silicon-rich silicon nitride (SiN_x) films from the point of view of the surface oxidation process. There are no large difference in both the reaction barrier and the formation energy of 1^st and 2^nd attack of H₃O⁺ and OH^- ion between on the films with anti-site silicon and on them with either silicon or nitrogen vacancies. However, our calculation shows that the 2^nd attack changes excess silicon atoms into Si(OH)_n molecules. Since the continuous attacks desorb Si(OH)_n molecules and leave the broken bonds in the films, we consider that the humid resistance of silicon-rich SiN_x films is not superior to that of Si₃N₄ films.