Strategic Selection of the Oxygen Source for Low Temperature‐Atomic Layer Deposition of Al 2 O 3 Thin Film

The influence of two oxygen source types, H 2 O and O 3 , on residual C‐related impurities in atomic‐layer‐deposited (ALD) Al 2 O 3 film is systematically examined. ALD Al 2 O 3 film grown using H 2 O contains negligible C‐related impurities irrespective of growth temperature. However, the C‐related impurity in film grown using O 3 exhibits strong dependence on growth temperature; only Al carbonate (Al‐CO 3 ) is present in film grown at 300 °C, but C‐related impurities with lower oxidation states, such as Al‐COOH and Al‐CHO, appear as the temperature decreases to 150 °C. This suggests that the reactivity of O 3 and H 2 O in the ALD process has a different temperature dependence; from a residual impurity perspective, compared to O 3 , H 2 O is a beneficial oxygen source for low temperature processes. Electrical properties, such as charge trapping and gate leakage current, are also examined. For a growth temperature of 300 °C, the film grown using O 3 is slightly superior to the film grown using H 2 O due to its high film density. However, the film grown using H 2 O demonstrates better electrical characteristics at low growth temperature, 150 °C.