Characterization and modeling of hot-carrier degradation in sub-micron NMOSFETS

Abstract

The continuous demand for higher packing density and faster operating speeds in modern digital CMOS circuits has driven the scaling of the metal-oxide-silicon field effect transistors. The use of scaling schemes which do not keep the internal electric fields constant results in highly energetic carriers in the scaled devices. This work presents a study of the degradation of MOSFET parameters, which effect circuit operation, due to processes initiated by injection of high energy carriers into the gate oxide. The characterization techniques used to measure and attribute these parameter shifts to the underlying processes, and the use of empirical, semi-empirical, and physical models to predict the time dependence of the parameter degradation during circuit operation have been investigated. The results of this work clearly highlight the deficiencies of the conventional degradation models and provide a basis for an approach to degradation modeling based on fundamental physical mechanisms.