The oxidation temperature dependence of the reliability of in situ pyrolytic-gas passivated (PGP) ultrathin silicon oxide gate films was investigated. PGP uses a little pyrolytic N2O gas during ultradry oxidation with pure O-2 at less than 1 ppb humidity. The reliability of the PGP films oxidized at 700-900 degreesC was evaluated by measuring the time-dependent dielectric breakdown (TDDB) lifetime (T-TDDB) and interface state density (D-it). It was found that the reliability for the PGP films oxidized at the low temperature of 700 degreesC is much like the others. That is, TTDDB of the 700 degreesC PGP films barely decrease in comparison with those of the 800-900 degreesC PGP ones and their D-it, are less than 7 X 10(10) eV(-1) cm(-2). This indicates that PGP has a potential for application to future low-temperature processes for fabricating nanometer-scale electronic and optoelectronic devices. (C) 2003 American Vacuum Society.