Resonant electron tunneling through defects in ultrathin SiO 2 gate oxides in MOSFETs

Abstract

To analyze defect-assisted elastic tunneling currents through ultrathin SiO 2 gate oxides in metal-oxide semiconductor field-effect transistors (MOSFETs), we have combined semiempirical microscopic tight-binding calculations with full-band Monte Carlo transport simulations. Two prototypical devices with channel lengths of 50 and 90 nm were considered. We find that defects having an area density larger than 10 11 cm −2 can enhance tunneling currents by several orders of magnitude in both devices. Resonant tunneling effects are predicted to be more pronounced for thicker oxides. For oxides thinner than 2 nm, hot electrons are unlikely to dominate gate leakage currents in the presence of defects.