Charge Capture Kinetics of Nitride Trap in Oxide-Nitride-Oxide Structures

Abstract

Oxide-Nitride-Oxide (ONO) structures have been fabricated on n- and p-type Si (001) substrates for a volatile memory application. Capacitance-voltage hysteresis is measured for the capacitors fabricated with the ONO structures. The difference of the flat band voltage is about 9.0V for the p-type substrates and 7.2V for the n-type substrates, respectively. Deep level transient spectroscopy is employed to investigate the energy levels of the charge traps and the capture kinetics of charge carriers in the ONO structures. The hole traps are observed to be at 2.44eV above the valence band maximum of the nitride layer or 0.24 eV above the valence band maximum of Si. The trap amplitude is found to be dependent upon the logarithm of the filling pulse time in the ranges from 10^-5 to 10^-2 s. This suggests that the charge traps in SONOS can be distinctly classified by investigating the capture kinetics of charges.