Temperature and electric field characteristics of time-dependent dielectric breakdown for silicon dioxide and reoxidized-nitrided oxides

摘要

TDDB characteristics of 150 /spl Aring/ reoxidized nitrided oxide (ONO) gate dielectrics were examined at temperatures from 77 K 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/sub bd/ performance while maintaining a similar temperature and electric field dependence compared to SiO/sub 2/. The low temperature activation energy for ONO and SiO/sub 2/ is found to be strongly temperature dependent, and the charge to breakdown, Q/sub bd/, is closely related to the electron trap generation/trapping rate rather than the amount of hole trapping for high field 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.