Defect-centric perspective of time-dependent BTI variability

With the continuous downscaling of CMOS device dimensions, (i) The number of gate oxide defects in each device decreases to a numerable level, while their relative impact on the device characteristics increases. (ii) The properties of each defect, such as its capture and emission times and its impact, are voltage and/or temperature dependent and widely distributed. (iii) The occupation kinetics of each defect is known to be stochastic. All of these result in each of the nominally identical nm-scaled devices behaving very differently during operation, resulting in increasing time-dependent variability (heteroskedasticity). Consequently, the lifetime of nm-sized devices cannot be predicted individually, but can be described in terms of time- (or workload-) dependent distributions.