A combined graphical / algebraic method for model reduction and analysis of chemical reaction networks: application to atomic layer deposition process

摘要

In many cases, the study of chemical engineering systems involves mathematical modeling of a potentially complex reaction network (RN) consisting numerous species and reactions. One example of such systems is atomic layer deposition (ALD), a thin-film manufacturing technique based on sequential reactions between gaseous precursors and a solid substrate to conformally deposit thin-film with accurately controlled composition. An ALD process starts with precursor adsorption on the substrate surface and proceeds with surface reactions by different mechanisms such as dissociation, transition state formation, ligand exchange, and densification; this reaction sequence ends with desorption and ultimately evacuation of reaction by-products from the reactor [1]. These reactions may occur with significantly different rates. For example in many cases the initial adsorption of precursor molecules on surface sites is barrierless and has a very short timescale; likewise equilibrium reactions result in pseudo-steady state conditions. Some ligand exchange surface reactions, on the other hand, may have a large energy barrier making them finite-rate processes.