Simulation of Gas- and Liquid-Phase Layer-By-Layer Deposition of Metal Oxides by Coarse-Grained Modeling

Atomic layer deposition (ALD) and chemical layer deposition (CLD) are techniques to produce conformal, atomically precise overcoats for materials in gas and liquid phases, respectively. Although it is a challenge to explicitly model ALD/CLD dynamics because of the large timescales involved, a combination of rule-based deposition actions, followed by molecular dynamics relaxations, can capture the net effect of one cycle. For ALD, we developed deposition rules for the trimethylaluminum (TMA)/H2O system over Al2O3 and SiO2 substrates. We also explore the CLD system of Al(O-sec-Bu)3/H2O solvated in 2-butanol over an Al2O3 substrate. In contrast to previous studies focusing on ligand exchange reactions, the gas-phase simulations predict that a TMA dissociation mechanism is the dominant growth mode, whereas the CLD simulations show a primary growth mode of deposition through precipitation of species that have already undergone reactions in solution. Together, these modeling results constitute a refinement of preexisting ALD models, leading to more accurate growth rate predictions, as well as a first step toward modeling more challenging liquid-phase processes.