Characterization of fast relaxation by oxide-trapped charges under BTI stress on 64 nm HfSiON/SiO2 MOSFETs

Abstract

For HfSiON/SiO2 n-type and p-type MOSFETs with a channel length L = 64 nm, the fast relaxation effect of oxide-trapped charges Q(ox) during interrupt for bias temperature instability (BTI) degradation measurement were investigated, and a model that compensated for this effect to predict lifetime t(L) was proposed. Experimental results show that the fast relaxation of Qox during threshold-voltage V-th measurement rapidly saturates within 1 s and is exponentially increasing for gate stress voltage V-g,V-str and exponentially decreasing for measurement duration t(m) but does not affect the BTI degradation mechanism. Using the V-g,V-str and t(m) dependence of Q(ox's) fast relaxation under BTI stress, t(L) prediction model was proposed to compensate the recovery effect by V-th measurement from BTI degradation measured in slow measurement (SM) condition with t(m) > 1 mu s. The proposed model increases the precision of the estimate of t(L) by considering the recovery effect of Qox even in SM. (C) 2020 The Japan Society of Applied Physics