Predicting the chemistry in CVD systems

Tailoring the chemical and physical nature of CVD deposits for specific applications requires understanding and controlling the chemical process occurring in a deposition reactor. This implies understanding the combined equilibrium, kinetic, and transport processes. The occurring processes produce composition gradients in the reactor which can cause variations in the deposition chemistry. Derived physical and mathematical models of possible mechanisms provide critical tools for manipulating and controlling the chemical and physical nature of CVD deposits. Examples of silicon boride deposition from SiH4, BCl3, and H2 mixtures are used to illustrate thermochemical modeling techniques which utilize the concept of partial equilibrium. Predictions of limits on the chemical behavior, and comparison of these limits with experimental observations are used to hypotheses deposition mechanisms