Statistical aspects of NBTI/PBTI and impact on SRAM yield

Quantitative simulations of the statistical impact of negative-bias-temperature-instability (NBTI) on pMOSFETs, and positive-bias-temperature-instability (PBTI) on nMOSFETs are carried out for a 45nm low power technology generation. Based on the statistical simulation results, we investigate the impact of NBTI and PBTI on the degradation of the static noise margin (SNM) of SRAM cells. The results indicate that SNM degradation due only to NBTI follows a different evolution pattern compared with the impact of simultaneous NBTI and PBTI degradation.