Angle resolved X-ray photoelectron spectroscopic study of ultrathin oxynitrides

We studied nitrogen distribution, concentration and chemical state in NO- and N₂O-exposed silicon oxide films, to understand the relationship between nitridation and suppression of stress-induced leakage current (SILC) resulting from Fowler-Nordheim (F-N) stress. We applied angle resolved X-ray photoelectron spectroscopy (ARXPS) and electron energy loss spectroscopy (EELS) to obtain information at less than 2-nm thick film-substrate interface layers. Si₃N₄-like layer is formed only at the film-substrate interface in NO oxynitride. Nitrogen atoms in N₂O oxynitride are broadly distributed in the oxynitride film near the interface because the interface moves deeper from the surface during N₂O nitridation due to both oxidation and nitridation proceed simultaneously. SILC of both NO and N₂O oxynitride decrease exceedingly. It is clear that both NO and N₂O nitridation is effective in suppressing SILC in spite of the quite difference in the distribution, concentration and chemical state of nitrogen atoms.