An improved methodology for monitoring NBTI induced threshold voltage shift of scaled p-MOSFETS

Conventional fast switching measurement method for NBTI characterization, which relates linear drain current degradation DeltaI_d to threshold voltage shift |DeltaV_t| based on the first-order expression |DeltaV_t| = intpartI_d/g_m, is shown to severely overestimate |DeltaV_t|. By taking into account the effect of source/drain series resistance and vertical-field induced mobility reduction, results obtained using an improved ultra-fast switching method are shown to be consistent with those obtained from alternative ultra-fast V_t and gate-voltage sweep methods.