Exchange Reactions during Atomic Layer Deposition of Ternary Group 13 Oxides and Nitrides

Due to interest in thin films of oxides and nitrides of group 13 elements (Al, Ga, and In) and their multicomponent combinations, their atomic layer deposition (ALD) processes are being actively investigated. However, often in ALD of multicomponent thin films, the composition of the injected precursor species and atomic percentage in the deposited film show significant discrepancies. In this study, exchange reactions of the group 13 element atoms with other group 13 precursors are suggested as a factor affecting the composition of the ternary oxides and nitrides during ALD. Density functional theory calculations are performed to investigate the surface chemistry of the group 13 oxides and nitrides. After the initial adsorption of the first precursor on the substrate, sequential adsorption of the secondary injected precursor with a different metal element is contemplated. By estimating the kinetic and thermodynamic factors of the exchange reactions, the reactivity trend of the group 13 elements is found to follow the trend Al > Ga ∼ In, allowing the more active Al to undergo exchange with Ga and In on each surface, thereby making the deposited films richer in Al. These findings can contribute to the advancement of thin film fabrication for next-generation semiconductor or display devices.