Fluorination of Al2O3 blocking layer for improving the performance of metal-oxide-nitride-oxide-silicon flash memory

Abstract

The characteristics of Al2O3 film grown by atomic-layer deposition as blocking layer with and without fluorine plasma treatment were investigated based on a capacitor structure of Al/Al2O3/TaON/SiO2/Si. The physical structure was studied by transmission electron microscopy, and the chemical composition of the blocking layer was analyzed by X-ray photoelectron spectroscopy and secondary ion mass spectroscopy. Moreover, the surface roughness of the blocking layer was investigated by atomic force microscopy. Compared with a capacitor with Al2O3 blocking layer, the one with fluorinated Al2O3 displayed higher programming/erasing speeds, better endurance property and better charge retention characteristic because the fluorination could reduce excess oxygen and traps in the blocking layer, thus forming a larger barrier height at the interface between the charge-trapping layer and the blocking layer. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.