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

摘要

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