Oxide field dependence of interface trap generation during negative bias temperature instability in PMOS

We focus in this study on the negative bias temperature instability (NBTI)-induced ΔN_IT phenomenon and we point out its relative gate-oxide thickness (T_OX) dependences. Studies are carried out in a large T_OX range, comparing the gate-oxide quality which was grown with or without nitrogen incorporation. We have developed an oxide field (F_OX) dependence for ΔN_IT and we show the two opposite effects of T_OX on the threshold voltage shift (ΔV_T). Simulation of both effects shows a good correlation with experimental results in pure oxide and confirms the reduced interface trapped charge effect in ΔV_T in nitrided devices. Results enable us to extrapolate the NBTI impact when T_OX is varied which allows us to determine in a useful way the security margin during the gate-oxide process optimization.