Process Optimization of HfAlO Trapping Layer for High Performance Charge Trap Flash Memory Application

Abstract

In order to explore the correlation between process control of HfAlO film deposition and memory performance, 10nm HfAlO trapping layer was deposited by atom layer deposition (ALD) system, using three different deposition sequence of HfO 2 and Al 2 O 3 thin films (1nmHfO 2 /1nmAl 2 O 3 , 1nmHfO 2 / 2nmAl 2 O 3 and 3nmHfO 2 /1nmAl 2 O 3 ). Comparing with HfO 2 single trapping layer, the HfAlO samples stacked in the sequence of 1nmHfO 2 /1nmAl 2 O 3 and 1nmHfO 2 / 2nmAl 2 O 3 have faster program/erase speed, lager memory window, and significantly improved data retention characteristics. This is due to the high dielectric constant of HfO 2 and appropriate band offset of HfO 2 to Al 2 O 3 , also with the extra interface inserted between HfO 2 and Al 2 O 3 .