Characteristics of n(+)-p junction leakage induced by tantalum pentoxide gate insulator and gate reoxidation

This letter will present the n(+)-p junction characteristics in tantalum pe ntoxide gate dielectric (Ta2O5) and gate reoxidation ambient. The n(+)-p ju nctions in n-type metal-oxide-silicon field effect transistor fabricated wi th different gate dielectrics and post-thermal conditions were characterize d by current-voltage measurements. The current-voltage measurements of junc tion leakage of Ta2O5 gate dielectric without gate reoxidation (MT1) show t he hump characteristics due to the precipitates of oxide near the junction depletion regime. And their leakage mechanism is phonon-assisted tunneling, which facilitates the hopping of electrons from the valence band into the shallow attractive Coulomb center via the interface states in the precipita te, leaving holes in the valence band. However, the junction leakage curren ts of Ta2O5 dielectric with gate reoxidation in hydrogen rich ambient (MT2) are higher than those of thermal oxide samples and their leakage mechanism is Schottky barrier lowering due to the enhanced diffusion of oxygen into the junction depletion region. (C) 2001 American Institute of Physics.