Abstract
Thermochemical modeling of a CVD process is relatively easy as compared to developing a full computational fluid dynamics description coupled with reaction kinetics for a geometrically complex system. As such, a thermochemical computational study should be performed before embarking on the development of any new CVD process or material. The results of this kind of analysis can provide important information about whether the phases of interest are thermochemically allowed to form from a proposed precursor system. It can also indicate whether secondary phases can form, and give some idea as to the maximum theoretical efficiency of the process. All of this information is predicated on reaching chemical equilibrium in a system, which is the fundamental assumption of thermochemical analysis. Yet, the presumption of chemical equilibrium is not realistic given the relatively short residence time of precursors in CVD reactors. However, reactions will proceed toward equilibrium to a sufficient extent that it is a reasonable assumption for gaining process insights. In addition, it is possible to constrain equilibrium calculations to provide a more realistic result, for example, by eliminating a phase from consideration when it is known that kinetic or steric conditions will prevent its formation even when it is thermochemically permitted.
