Method of estimating a lifetime of hot carrier of mos transistor, and simulation of hot carrier degradation

Abstract

A hot carrier lifetime of a MOS transistor is estimated, depending on model formulas: 1/τ=1/τ+1/τ; τ∝1·I·exp(a/|V|), where τ denotes a lifetime, Idenotes a substrate current, Idenotes a drain current, Vdenotes a substrate voltage, τdenotes a lifetime at the time the substrate voltage V=0, τdenotes a quantity representing deterioration of a lifetime at the time the substrate voltage |V|>0, and mb and 'a' are model parameters. Furthermore, a parameter Age representing a cumulative stress quantity is calculated depending on model formulas: Age=Age+Age; Age=∫1/H[I·I]·exp(−a/|V|)dt, where t denotes time, His a model parameter, Agedenotes a parameter representing a cumulative stress quantity at the time the substrate voltage V=0, and Agedenotes a quantity representing an increase of the cumulative stress quantity at the time the substrate voltage at |V|>0. Thereby, a lifetime in actual use is determined with accuracy even when a substrate voltage is applied, and circuit characteristic degradation is simulated with high accuracy.