Chemical configuration of nitrogen in ultrathin Si oxynitride on Si(100)

Chemical bonding structures of nitrogen within very thin oxynitride films on Si(100) have been investigated by high-resolution photoemission spectroscopy using synchrotron radiation. The oxynitride films nitrided by the rapid thermal process with NO and N₂O are systematically compared. Two distinct N $1s$ components are resolved for both films with a binding-energy difference of {~}0.61 eV, which are assigned to the N atoms at the interfaces and those in the SiO₂ matrix. Both components are unambiguously attributed to represent a N-Si₃ like chemical configuration with three nearest-neighbor Si atoms. The energy shift of 0.61 eV between these components is thought be due to the second-nearest-neighbor effect combined with core-hole screening. The difference between N₂O- and NO-nitrided films and the interface suboxide species identified by Si $2p$ core levels are discussed.