Soft X-ray absorption and emission study of silicon oxynitride/Si(100) interface

The atom-specific electronic structure at the oxynitride/Si interface was investigated by soft X-ray absorption and emission spectroscopy in order to elucidate the relationship of the incorporation effect of nitrogen atoms at the interface with the performance of metal-oxide-silicon devices. At the interface, the conduction band minimum (CBM) decreases when the concentration of N atoms at the interface increases. For valence states, the width of the nonbonding states of N atoms increases when the concentration of N atoms is high, indicating that an inhomogeneous interface is formed. Thus, the excessive incorporation of nitrogen atoms at the SiO₂/Si(100) interface decreases CBM and induces the formation of a more inhomogeneous interface, which decreases carrier mobility in the channel region.