Impact of NBTI/PBTI on SRAM Stability Degradation

Abstract

We investigate the impact of negative-bias temperature instability (NBTI) on the degradation of the static noise margin (SNM) and write noise margin (WNM) of a SRAM cell. This is based on the quantitative simulation of the statistical impact of NBTI on p-MOSFETs corresponding to a 45-nm low-power technology generation. Due to the increasing importance of positive-bias temperature instability (PBTI) of n-MOSFETs with the introduction of high-/v/metal gate stacks, we also explore the additional impact of PBTI on statistical SNM and WNM degradation behavior. The results indicate that NBTI-only induced SNM and WNM degradations follow different evolutionary patterns compared to the impact of simultaneous NBTI and PBTI degradation, and high distribution moment information is required for the reconstruction of noise margin distributions.