A flash memory, which uses a floating-gate SiO2/Si3N4/SiO2 (ONO) structure for the next generation, non-volatile memory applications, has serious problems to overcome in the context of scaling down the device size. In this study, Al2O3/Ta2O5/Al2O3 (ATA) and Al2O3/TaAlO4/Al2O3 (A/TAO/A) multilayer films were fabricated to replace the conventional ONO structure. The structures and thicknesses of the multilayers were analyzed by HRTEM and ellipsometry. All films were found to be comprised of amorphous phases, and interfacial layers (AlSiO3) were observed in both films. The electrical properties of the A/TAO/A films were better than those of the ATA films. Program/erase cycle tests were performed, and initial memory windows were maintained after 104 program/erase cycles with both films.

Keywords: Flash, ONO, Charge trap, High-k dielectrics, Ta2O5, Ta1Al1O4.