GAS PHASE CHEMICAL KINETICS AND THE DETAILED MODELING OF CHEMICAL VAPOR DEPOSITION PROCESSES (SILICON EPITAXY, DICHLOROSILANE)

The goal of the research presented in this thesis is the development and use of tools for building reaction mechanisms and determining rate parameters of gas phase reactions for use in detailed models of chemical vapor deposition (CVD) processes. These models are important for continued improvements in the manufacture of microelectronic circuits and other products for which CVD is an important processing step. A key missing piece of information for many systems is an understanding of the gas phase chemical kinetics. The system considered most in this thesis is silicon epitaxy from dichlorosilane, but the methods developed and used have wider applicability.;Pulsed laser powered homogeneous pyrolysis (LPHP) is a technique capable of measuring high temperature kinetics of reactions important in CVD processes. This method allows us to separate homogeneous from heterogeneous reactions. Results of computational and experimental studies showing the utility and range of applicability of this method are presented. These studies provide a new level of understanding of the LPHP experiment and demonstrate that it can provide reliable measurements of rate parameters under conditions relevant to CVD processing. Results of an experimental study of the homogeneous decomposition of dichlorosilane using the LPHP method are also presented. These provide the first experimental support for the high activation energy for this reaction, near 75 kcal/mol, that is predicted by ab initio calculations.;Computational chemistry can also be used to calculate rate constants and deduce gas phase chemical mechanisms. We present results from an ab initio molecular orbital study of the thermochemistry and decomposition kinetics of the chlorinated disilanes. In addition to characterizing the expected reaction paths, we discovered additional reaction paths that are predicted by the calculations. A detailed mechanism for the homogeneous decomposition of the chlorinated silanes with rate parameters based on these ab initio molecular orbital calculations is presented and analyzed. Simulations of isothermal decomposition, analysis of reaction rates and sensitivity coefficients, and a reduced mechanism for dichlorosilane decomposition are presented. This work provides a much more detailed understanding of the processes involved in the multi-step thermal decomposition of dichlorosilane than was previously available.