In this study, we investigated the electrical properties of Al2O3/Ta2O5/SiO2 (ATS) films using various tunnel oxide (bottom oxide) thicknesses at different annealing temperatures. With a 5 nm thick tunnel oxide, the program/erase conditions were 11 V for 100 ms and -13 V for 100 ms, respectively. The memory window of the film was 0.91 V. To improve the film quality, the film was annealed at 900 degrees C. The thickness of the multi-layer film decreased after the annealing process. The program/erase conditions of the annealed films changed to 9 V for 100 ms and -13 V for 100 ms, respectively. The memory window of the annealed film was 1.05 V. The retention properties of the as-deposited and annealed films did not change up to 10(4) cycles. The electrical characteristics of ATS structures using various tunnel oxide thicknesses at different annealing temperatures were investigated for application in next generation non-volatile memories.

Keywords: Ta2O5; high-k; MOCVD; retention; annealing