Effects of thermal reoxidation on the time to dielectric breakdown of ultrathin nitrided oxides have been studied. At atmospheric pressure it was found that a proper reoxidation processing is necessary for optimizing the charge-to-dielectric breakdown of an arbitrarily nitrided 100A-thick oxide. For the more heavily nitrided oxides, a higher-temperature or longer-time reoxidation is required to reduce the large quantity of electron traps in the nitrided films. A superior endurance behavior (Qbd = 92 C/cm2) with a stress current of 100 mA/cm2 was achieved for the ultrathin oxides nitrided at 900°C for 30 min and subsequently reoxidized at 950°C for 30 min as the pure oxide exhibited a charge-to-breakdown of 27 C/cm2 with the same current density. Positive fixed charges via the nitrogen radicals or defects were shown to be the main cause of the negative flatband shift of the nitrided or reoxidized oxides. copyright.