Initiated tunnel current through thin gate oxide generation of minority carriers in Si-MIS-structures

摘要

The nanometer scaling of metal-oxide-semiconductor (MOS)-devices requires a transition to thin and ultrathin gate insulators. Their tunneling conductance in such insulators essentially changes of the process of the minority carrier (MC) generation. In n-Si-MOS-structures with a insulator thickness below 100A the tightly growth and sharply dropping peak is appeared on the time dependence of the generation current I_g(t). The peak is completed a transition of a MOS-structure to the equilibrium inversion state In this state the stationary tunnel current I_(t∞) flows through a MOS-structure. The amplitude peak and its position in the time strongly depend from the structure construction, its prior history and external factors and can to change in wide limits. The sequential description of phenomenon is based on presentations about a impact ionization of the MC band, tunneled through oxide in semiconductor by heat electrons. The developed algorithm allows to divide of the contributions of generation and tunnel current component in dependences I(t, V_g) and to characterize of oxide tunnel conductance. The algorithm too allows to determine set of base electronic characteristics of MOS-structures: the impact ionization coefficient α, sign and integral density of fixed charge in a oxide, a rate of the MC generation and a velocity of the surface recombination, and the time evolution of the semiconductor surface potential. These data are base for the physical diagnostic of degradation mechanisms of the semiconductor/insulator interface region. The strong dependence of kinetics of the thermo-tunnel generation of MC from a composition of a surrounding medium can to use for a creation of gas sensors of new type.