Modeling alumina atomic layer deposition reaction kinetics during the trimethylaluminum exposure

A model describing the reaction kinetics and surface species dynamics for trimethylaluminum (TMA) half-reactions of alumina atomic layer deposition (ALD) is presented. The model is based on reaction energetics data taken from published quantum chemical computational studies; these data are used to determine kinetic parameters using statistical thermodynamics and absolute reaction rate theory. Four TMA half-reactions were modeled to account for TMA adsorption and subsequent reaction on a range of growth surfaces spanning bare to fully hydroxylated states. By coupling the reaction rate models with surface species conservation equations, we create a dynamic model useful for examining the relative rates of completing surface reactions. Numerical simulations performed with the model reveal that it is a combination of TMA adsorption on hydroxylated and bare surface oxygen sites that produces Al adsorption rates comparable with those found for saturating ALD growth of alumina.