The charge trapping properties of HfO 2 thin films for application in charge trap memories are investigated as a function of high-temperature postdeposition annealing (PDA) and oxide thickness in the TaN/Al 2 O 3/HfO 2/SiO 2/Si structure. The trap density (N T) in HfO 2, extracted by simulating the programming transient, is in the 10 19–10 20 cm-3 range, and it is related to film thickness and PDA temperature. Diffusion phenomena in the stack play a significant role in modifying N T in HfO 2 and the insulating properties of the Al 2 O 3 layer. The memory performances for 1030 C PDA are promising with respect to standard stacks featuring Si 3 N 4.