Reactor scale simulation of an atomic layer deposition process

To simulate an atomic layer deposition (ALD) process in a reactor scale, three-dimensional deposition of Al₂O₃ from trimethylaluminum and ozone inside a viscous flow reactor is investigated. The chemistry mechanism used includes both gas-phase and surface reactions. The simulations are performed for a fixed operating pressure of 10torr (1330Pa) and two substrate temperatures at 250°C and 300°C. The Navier-Stokes, energy, and species transport equations are discretized through the finite volume method to simulate transient, laminar and multi-component reacting flows. It is found that the larger surface reaction rate constant, and the greater concentrations of gaseous reactants at the substrate result in higher deposition rates on the substrate at 300°C. At a fixed substrate temperature, the deposition rate distributions are the same among all the cycles that indicate a constant growth rate at each cycle. As a result, Al₂O₃ growth rates of 3.78 angstrom/cycle and 4.52 angstrom/cycle are obtained for the substrate temperatures of 250°C and 300°C, respectively.