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

The effects of Al doping on the charge-trapping characteristics of ZrO
₂
are investigated based on Al/Al
₂
O
₃
/Al-doped ZrO
₂
/SiO
₂
/Si structure. XRD and XPS show that the crystallization of ZrO
₂
and the formation of silicate interlayer at the ZrO
₂
/SiO
₂
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 ZrO
₂
as the charge-trapping layer (CTL) than the one with pure ZrO
₂
. However, excessive Al doping in ZrO
₂
severely reduces the dielectric constant and electron traps of the CTL, thus leading to much lower program speed for the device.