Computer Simulation of Reactors for Chemical Vapor Deposition

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Chemical vapor deposition (CVD) is an important process in the manufacture of microelectronic and optical devices. It is used to deposit layers of epitaxial semiconductors, compound semiconductors, conductors, and insulators. Although the thickness of the deposited film varies according to the application, the films must be produced with controllable properties (purity, composition, texture, thickness, etc.). The tolerance limits on the properties are very stringent in electronic and optical material processing. As the devices become smaller in size, the requirements become even more stringent. In particular, the uniformity of film thickness is critical in maintaining the same performance characteristics across each substrate and from sample to sample. Because the film uniformity is governed by the access of the precursor gases to the substrate, a clear understanding of the governing transport processes is essential to achieve uniformity of the deposition thickness and composition over large areas. The currently available three-dimensional computational models for CVD reactors are based on simplifications with regard to the transport processes and chemical kinetics and are of limited use. The objective of this research is to develop a complete model based on the full three-dimensional unsteady form of the governing equations for CVD reactor flows. Due to the use of efficient and accurate numerical procedures, the model will require only a few minutes to run a workstation. Therefore, the model can be used in a routine manner for design, research and optimization. It will lead to better understanding of the transport phenomena and reactions in CVD processes and will aid in the design of reactors capable of producing uniform film thickness and composition over large areas.