Modeling chemical vapor deposition of thin solid films

Chemical vapor deposition is a process by which thin solid films are deposited on solid substrates. A multispecies chemically reacting gas flows past a heated substrate on which the deposition takes place via a series of heterogeneous chemical reactions. The growth rate is determined by the competition between the diffusive and convective transports of species, the homogeneous and heterogeneous chemical kinetics, and the morphology of the interface.; In chapter 2, a macroscopic model is proposed that couples the flow to the growing film via the equations governing the morphological evolution of the film-gas interface. The surface is modeled as a separate anisotropic elastic phase, and such phenomena as surface species diffusion, heat conduction and chemistry are accounted for. The driving force at the surface is identified, and a kinetic relation linking it to the growth velocity is proposed. A specialization of this framework to the case of a multicomponent ideal gas and a linearly elastic solid film is considered.; In chapter 3, we examine a multicomponent gas flow in a vertical axisymmetric MOCVD reactor. A two-parameter asymptotic analysis yields, in the limit of small aspect ratio and Mach number, a set of approximate governing equations and approximate boundary conditions at the showerhead and the gas-film interface. An analytical solution to the steady-state problem is derived. This solution is of the similarity type, thus insuring a uniform temperature and chemical composition profiles along the film surface.; Finally, in chapter 4, the growth of a generic film via a ledge-and-terrace mechanism is examined. Of interest is the interaction between the surface microstructure and the chemical kinetics by which the adsorption, desorption and incorporation of species occur. A step-flow model is proposed and its specialization to the case of a binary compound illustrates the dependence of the averaged growth rate on the chemical composition of the gas phase and the surface morphology.