Probabilistic defect occupancy model for NBTI

Abstract

A new Negative Bias Temperature Instability (NBTI) model based on the probability of charge/discharge of defects in devices is presented. The model correctly describes the main experimental NBTI features, such as the threshold voltage shift (ΔV <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</inf> ) evolution under DC or AC stresses, its frequency and duty cycle dependence and the statistical ΔV <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</inf> distribution in small transistors. Finally, the model is used to explain the dependence of NBTI degradation on the stress/relaxation times, frequency and duty cycle in terms of defect occupancy.