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

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 V_ds and various gate voltages V_gs. The threshold voltage V_l and interface trap density N_it were recorded as a function of stress time. It is found that at low V_gs stress when equal numbers of interface traps are created, the shift of V_l is larger in hydrogenated transistors than in deuterated transistors. Increasing V_gs to 1/3V_ds produces no noticeable difference of V_l shift in these two kinds of transistors. However, further increasing V_gs results in larger V_l shift in deuterated transistors than in hydrogenated ones. From a quantitative analysis, the contribution of oxide charge trapping to V_l 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.