The buildup of interface states with high field (HF) stressing have been observed in thermally grown oxide, N2O nitrided oxide (NO), and reoxided nitrided oxide (RNO). The DLTS technique was used to analyze the electronic properties of the Si/SiO2interface. We show that N2O nitridation of SiO2changes the electronic distribution of states at the Si/SiO2interface after HF electrical stress. Our results indicate that this nitrogen plays an important role in preventing the creation of a center atEt1=0.34 eV below the bottom of the conduction band. However, the nitrogen is responsible for a new level atEt2=0.22 eV below the bottom of the conduction band after the NO device is stressed. Also, reoxidation and increasing time of the reoxidation shift the maximum of the peak level away from theEt2towardEt1. ©1995 American Institute of Physics.