MOS structure threshold voltage model by rigorously considering quantum mechanical effect

Quantum Mechanical Effects (QME) on deep-submicron MOSFET characteristics are analyzed from first-principle theory. The single subband occupation approximation often used in earlier works is proved to be invalid, based on rigorous consideration of subband structure and carrier distribution. The concepts of surface layer quantum effective density of states (SQEDOS) and the surface layer classical effective density of states (SCEDOS) are proposed through which a Vth shift model due to QME is derived. The model reveals the physical nature of the influence of QME on the Vth shift and gives consistent results with experiments.