Modeling and Simulation of Hot Carrier Effects in MOSFETs

Enhanced impact-ionization effects in scaled MOSFETs severely degrades the performance and reliability of VLSI circuits. Hot carriers generated by impact-ionization affect device characteristics such as drop of source-to-drain breakdown voltage due to substrate currents, threshold voltage shifts and/or degradation of channel conductance due to trapped electrons in gate oxide. Especially the latter aspect of hot carriers is extremely important to achieve high reliability for very small devices. The purpose of this paper is to estimate these effects using computer simulation to clarify their dependence on process and device parameters. In order to calculate gate currents correctly, the motion of electrons in SiO2 has been properly treated.