Improving Retention Properties of ALD-AlxOy Charge Trapping Layer for Non-Volatile Memory Application

Abstract

In this work, the charge retention properties of the thermal ALD-Al2O3 trapping layer with metal-oxide-oxide-oxide-silicon (MOOOS) gate stack have been investigated for non-volatile memory application. The precursor gas concentrations were changed to engineer the band gap of the AlxOy trapping layer and the effect of AlxOy post-deposition annealing on charge retention properties was studied. The Al2O3 layer with trimethyl aluminum (TMA): H2O gas flow ratio of 1:1 and deposition pulse time of 1 s per each cycle showed the band gap of 4.49 eV , which is suitable for charge trapping layer. The memory retention properties of the ALD-Al2O3 MOOOS device was investigated by performing high-frequency capacitance-voltage measurement and compared to the device having a SiNx charge trapping layer. The 10 nm AlxOy trapping layer showed the improvement in charge retention properties after low-temperature post-deposition annealing in N2 ambient as compared to that of SiNx trapping layer with relatively large flat band voltage shift of 2.79 V. The multilayer Al2O3-MOOOS gate stack is suitable for the non-volatile memory application with good retention properties as compared to different oxides non-volatile memory devices.