Dependence of barrier height and effective electron mass on gate oxide thickness and nitrogen concentration at SiO x N y /Si interface

Abstract

In many device modeling and simulations, it is commonly assumed that the barrier height and the effective electron mass are constant regardless of the oxide thickness and the interfacial nitrogen concentration for nitrided oxides. In this work, we have examined the dependence of barrier height and effective electron mass on gate oxide thickness and nitrogen concentration at SiO_xN_y/Si interface. From the measurement of the direct tunneling and Fowler-Nordheim (FN) tunneling currents we have been able to determine both the barrier height and the effective electron mass without assuming a value for either the effective electron mass or the barrier height. It is observed that with the interfacial nitrogen concentration increased, the barrier height decreases, and the effective electron mass increases. On the other hand, it is also observed that the reduction in the gate oxide thickness leads to a decrease of the barrier height but an increase in the effective electron mass. These results are explained using the electronic structures of SiO₂ and SiO_xN_y.