Variability in device degradations: Statistical observation of NBTI for 3996 transistors

Degradations of thousands of transistors have been observed in a practical time. A novel device array circuit suitable for measurement-based statistical characterization has been devised to facilitate parallel stress bias application to capture negative bias temperature instability (NBTI). The experimental results show that log-normal distributions approximate the distribution of power-law exponents very well and that the variation in magnitude of threshold voltage shifts bears an inverse relation to the channel areas of transistors. The variability in degradations under an AC-stress condition is also presented for the first time.