LaTiON/LaON as band-engineered charge-trapping layer for nonvolatile memory applications

Charge-trapping characteristics of stacked LaTiON/LaON film were investigated based on Al/Al2O3/LaTiON-LaON/SiO2/Si (band-engineered MONOS) capacitors. The physical properties of the high-k films were analyzed by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The band profile of this band-engineered MONOS device was characterized by investigating the current-conduction mechanism. By adopting stacked LaTiON/LaON film instead of LaON film as charge-trapping layer, improved electrical properties can be achieved in terms of larger memory window (5.4 V at +/- 10-V sweeping voltage), higher program speed with lower operating gate voltage (2.1 V at 100-mu s +6 V), and smaller charge loss rate at 125 A degrees C, mainly due to the variable tunneling path of charge carriers under program/erase and retention modes (realized by the band-engineered charge-trapping layer), high trap density of LaTiON, and large barrier height at LaTiON/SiO2 (2.3 eV).