CHARGE CAPTURE KINETICS OF NITRIDE TRAPS IN OXIDE-NITRIDE OXIDE(ONO) STRUCTURES

摘要

Oxide-Nitride-Oxide (ONO) structures have been fabricated on nand p-type Si (001) substrates for volatile memory device applications. Capacitance-voltage hysteresis loops are measured for the capacitors fabricated with ONO structures. The difference of the flat band voltage is about 9.0V for p-type substrates and 7.2V for n-type substrates, respectively. Deep level transient spectroscopy is employed to investigate energy levels of charge traps and capture kinetics of charge carriers in 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 with the capture cross section of 3.99x10~(-15) cm~2. 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.