New leakage mechanism in sub-5-nm oxynitride dielectrics

Abstract

Conduction current in thin (3.5-6.5 nm) oxynitride dielectrics prepared by rapid thermal annealing of SiO2 films in NH3 ambient at high temperature (1100°C) is studied. Significantly high leakage currents at low fields and independent of temperatures has been observed in films with thickness of 4.5 nm or less. The enhanced conduction is proposed to be direct tunneling current via electron traps located in the dielectric film. This new leakage mechanism in sub-5-nm oxynitride dielectric is different from the thicker (5.5 nm or higher) films where the conduction is only slightly enhanced and is temperature dependent. This leakage mechanism could open new applications where significant tunneling current are needed for thicker (<5 nm) films.