High-k dielectric materials for the gate oxide of a MIS capacitor: effect of interface states on the C–V characteristics

Abstract

The capacitance-voltage (C---V) characteristics of metal-insulator-semiconductor (MIS) capacitors are investigated by solving in 1D the self-consistent equations using the Silvaco ATLAS device simulation package. In this paper, ambient and high temperature C---V characteristics for both positive and negative interface charge densities are studied. The results obtained from the simulation show that the C---V characteristics at ambient temperature change from high frequency to a low frequency for $$D_\mathrm{it} > \hbox {1e12}\, \hbox {cm}^{-2}\,\hbox {eV}^{-1}$$Dit>1e12cm-2eV-1. We find that the shift in threshold voltage has a strong dependence on the positive and negative interface charge densities. Also, a less significant shift in threshold voltage for the highest temperature operation is found which is in the opposite direction for negative and positive interface charge densities. Electrons and holes that occupy interface traps become charged and contribute to the threshold voltage shift and a hump in the C---V characteristics.