TEMPERATURE AND ELECTRIC-FIELD CHARACTERISTICS OF TIME-DEPENDENT DIELECTRIC-BREAKDOWN FOR SILICON DIOXIDE AND REOXIDIZED-NITRIDED OXIDES

TDDB characteristics of 150 Angstrom reoxidized nitrided oxide (ONO) gate dielectrics were examined at temperatures from 77K to 400 K. These ONO films were processed with different conditions of rapid thermal nitridation (RTN) and rapid thermal re-oxidation (RTO). Optimized ONO films show better Q(bd) performance while maintaining a similar temperature and electric field dependence compared to SiO2. The low temperature activation energy for ONO and SiO2 is found to be strongly temperature dependent, and the charge to breakdown, Q(bd), is closely related to the electron trap generation/trapping rate rather than the amount of hole trapping for high held stress. To further verify the effect of hole trapping on TDDB, X-ray irradiation was applied to wafers at different process steps. The results clearly show that the amount of hole trapping does not correlate with the charge to breakdown.