Separation of Hole Trapping and Interface-State Generation by Ultrafast Measurement on Dynamic Negative-Bias Temperature Instability

Hole trapping and interface-state components of negative-bias temperature instability (NBTI)-induced threshold-voltage shift are separated via ultrafast switching measurement. Based on the phenomenological observation that dynamic NBTI is determined by a cyclic hole trapping/detrapping mechanism and that interface-state generation is relatively permanent, the time dependence of hole trapping during stress is precisely determined and then subtracted from the overall degradation of the first cycle to yield the time dependence of interface-state generation. Interface-state generation is shown to exhibit power-law time dependence with an initial exponent of ~0.5, which subsequently decreases to a steady value of 0.25 after ~1000 s at the stress condition studied (oxide field ~9 MV/cm). This evolution is shown to be consistent to that obtained via the charge-pumping method, confirming the underlying principle of the approach.