Understanding SRAM High-Temperature-Operating-Life NBTI: Statistics and Permanent vs Recoverable Damage

We show, using deconvolution, SRAM Vmin shift statistics yield a spread that follows Poisson area scaling and a time- and voltage-dependence of t1/6 and V3, respectively. This is demonstrated to be consistent with permanent NBTI shift (Si-H bond breaking) relevant for end-of-life extrapolation. In contrast recoverable NBTI shift (hole trapping/detrapping) is shown to be only a function of stress duty and can be very small for realistic product duties.