Novel fabrication process to realize ultra-thin (EOT = 0.7 nm) and ultra-low-leakage SiON gate dielectrics

The reaction mechanism of nitrogen atoms with Si was investigated based on first principles calculations and experimental results to realize ultra thin SiN-based SiON films with high insulation and good interfacial properties. Incorporation rate of nitrogen atoms into Si has a great influence on arranging 3-fold coordinated N atoms uniformly. By arranging 3-fold coordinated N atoms into the Si sub-surface layer uniformly, oxidation-resistant Si₃N₄ film can be formed and O atoms were successfully incorporated into the SiN/Si interface with minimum disruption of SiN structures. By using this novel process, a high-quality ultra-thin gate SiON film with an equivalent oxide thickness (EOT) of 0.7 nm and a leakage current (J_g) of 95 A/cm², i.e., 1/10 or less than that of traditional SiON films was realized. Mobility is not reduced to less than 89% of an ideal SiO₂ film