Hot-carrier-induced oxide charge trapping and interface trap creation in metal–oxide–semiconductor devices studied by hydrogen/deuterium isotope effect

Abstract

A method based on the hydrogen/deuterium isotope effect is proposed to separate and quantify the effects of interface trap creation and oxide charge trapping on hot-carrier-induced degradation in n-channel metal–oxide–semiconductor field-effect transistors (MOSFETs). Hydrogenated and deuterated transistors were subjected to hot-carrier stress with a fixed drain voltage Vds and various gate voltages Vgs. The threshold voltage Vt and interface trap density Nit were recorded as a function of stress time. It is found that at low Vgs stress when equal numbers of interface traps are created, the shift of Vt is larger in hydrogenated transistors than in deuterated transistors. Increasing Vgs to 1/3Vds produces no noticeable difference of Vt shift in these two kinds of transistors. However, further increasing Vgs results in larger Vt shift in deuterated transistors than in hydrogenated ones. From a quantitative analysis, the contribution of oxide charge trapping to Vt shift is separated from the contribution of interface trap creation. The results suggest that interface trap creation is the dominant mechanism for hot-carrier-induced degradation in n-channel MOSFETs.