Model of the Negative-Bias Temperature Instability of p-MOS Transistors

Abstract

A new quantitative model of the negative-bias temperature instability (NBTI) of p-MOS (metal-oxide-semiconductor) transistors is developed. The model is based on the reaction of the depassivation of surface states at the Si–SiO2 interphase boundary (IPB) and hydrogen-containing hole traps near the Si–SiO2 IPB by positively charged hydrogen ions H+, accumulated in the p+-type inversion layer of the silicon substrate. The dependences of the surface and space charges in p-MOS transistors on the NBTI time are controlled by the kinetics of H+-ion diffusion and drift from the silicon substrate to the Si–SiO2 IPB. The effect of the gate voltage on the NBTI is explained by the effect of the electric-field strength on the H+ ion segregation coefficient at the Si–SiO2 IPB. The relaxation of positive space charge introduced into the gate dielectric during NBTI is described by the tunnel discharge of oxide traps by silicon-substrate electrons.