In this paper, rapid thermal processing (RTP) N2O polyoxides were studied in terms of oxidation temperature and thickness with O-2 oxidation polyoxides as comparison. Atomic force microscopy, transmission electron microscopy, and secondary ion mass spectroscopy measurements were employed to correlate the electrical characteristics with the physical structures. Results showed that RTP N2O-grown polyoxides exhibited better characteristics on the leakage current, E-bd, trappings and Q(bd). It was found that it was the proper amount of nitrogen incorporated in the polyoxide improving the interface of the polyoxide/polysilicon, consequently improving the electrical quality. The initial hole-trapping phenomenon during the constant current stress, which was due to the incorporated nitrogen, was also observed in the N2O-grown polyoxides. The two-step RTP process, i.e., first RTP oxidizing the polysilicon in O-2 and then RTP oxidizing in N2O, could achieve polyoxide of good characteristics by incorporating the proper amount of nitrogen into the polyoxide. (c) 2005 The Electrochemical Society.