BTIarray: A Time-Overlapping Transistor Array for Efficient Statistical Characterization of Bias Temperature Instability

A transistor array has been developed that is capable of efficiently collecting parametric data for a statistical model of bias-temperature instability (BTI) degradation. This BTIarray uses a time-overlapping technique, in which all transistors in the array undergo BTI stress or recovery bias in parallel, which greatly reduces the measurement time for a large number of transistors. An implementation using 65-nm technology validated the time-overlapping concept. The use of this array reduces the time to measure the statistical threshold voltage shifts of 128 transistors from a month to within a day while retaining precision as high as 50 μV (rms). Experiments showed that the statistical distribution of the time exponent for the degradation model of the pMOS transistor was log-normal.