Improved Charge-Trapping Characteristics of ZrO2 by Al Doping for Nonvolatile Memory Applications

The effects of Al doping on the charge-trapping characteristics of ZrO2 are investigated based on Al/Al2O3/Al-doped ZrO2/SiO2/Si structure. XRD and XPS show that the crystallization of ZrO2 and the formation of silicate interlayer at the ZrO2/SiO2 interface are effectively suppressed by Al incorporation, thus resulting in better electrical performance with larger memory window and better retention for the memory device with Al-doped ZrO2 as the charge-trapping layer (CTL) than the one with pure ZrO2. However, excessive Al doping in ZrO2 severely reduces the dielectric constant and electron traps of the CTL, thus leading to much lower program speed for the device.