Phase change memory cell using Ge2Sb2Te5 and softly broken-down TiO2 films for multilevel operation

摘要

A phase change memory cell was fabricated by stacking plasma-enhanced cyclicnchemical-vapor-deposited Ge2Sb2Te5 u0002GSTu0003 and atomic layer deposited TiO2 thin films. Differentnpairs of resistance states were obtained by controlling the current flow, which can be used to achievenhigher memory density by multilevel operation. The multiresistance states of the stacked cell werenexplained by the resistance switching phenomena of TiO2 and the thermoelectric phase changenproperties of GST. The phase change characteristics of GST could be altered by controlling thendegree of filament formation in the TiO2 layer, which eventually changed the phase change volumenin the GST.