A Unified Approach for Modeling CVD Processes

A modeling technique based on bond graph methods was proposed for the analysis and understanding of chemical vapor deposition (CVD) processes. In contrast with pure numerical techniques, the proposed modeling tool provides an understanding of the behavior of the process and an appreciation of interactions between the various phenomena in the system. The essential bond graph tools required for modeling any CVD system were developed. Furthermore, since the tools are not system specific, the development of a general computer program capable of modeling any complex CVD pro-cess was facilitated. The modeling power of this new method was illustrated through a study of SiO ~ deposition process using tetraethoxysilane. The bond graph method allowed repeated guesses at the phenomena with minimal effort and re-sulted in an enhanced understanding of the process. In addition, the application of the bond graph method as an analytical tool for CVD processes where the physics of the phenomena is known is illustrated through several hypothetical ex-amples. CVD processes, in general, are highly complicated and involve several phenomena. In a typical process, the re-agent gas molecules are transported near the surface of the substrate by either convection or diffusion. These gas mol