Study of Transistor and Product NBTI Lifetime Distributions

NBTI has been extensively studied to understand physics of degradation in recent years. However, little has been done to find out the lifetime distributions of NBTI at both transistor and product level, which are important in reliability prediction and improvement. In this paper, Monte-Carlo simulation is carried out to study the NBTI lifetime distribution at transistor level. Lognormal distribution is found to have the best fit. Product level NBTI lifetime distribution is studied through rare event simulation. Result shows that Weibull distribution has a better fit than lognormal distribution at product level. Acceleration test result of 90 nm SRAM cache NBTI degradation is compared with the simulation results and a good agreement is observed.