| Chemical vapor deposition (CVD) is a widely used method for preparation of thin films and micron-thick coatings. Up to now, major advances in the development of the CVD process and in obtaining high-quality films and coatings have been achieved by trial and error. In the present work, a multi-length scale computer modeling and simulation methodology is developed to analyze the CVD process and the evolution of the film/coating microstructure during deposition.; The multi-length scale model developed in the present work consists of three parts each analyzing the CVD process at different length scales: (a) At the chemical reactor length scale, the CVD process is analyzed by solving the appropriate reactive-gas, fluid-dynamics, heat-transfer boundary value problem; (b) At the atomic scale, a kinetic Monte Carlo method is utilized to model, in a stochastic manner, the deposition process of single crystalline films and the growth of polycrystalline film facets, and (c) At the grain scale, an improved van der Drift-type model is employed to simulate the evolution of microstructural and crystallographic texture of polycrystalline films and coatings. The three modeling schemes are coupled to each other so that the results obtained on one length-scale can be utilized when modeling is carried out at a different length scale. The reactor scale modeling predicts the concentration of gas-phase and surface species on the deposition surface which are used as input to the atomic scale modeling. Also, the atomic scale model predicts the growth rates of (111)- and (100)-oriented surface facets and the rates of defect incorporation which are used as input to the grain scale modeling. To ensure the consistency in prediction of different models, the exchange of information between the models is enabled to be in both directions.; The method developed in the present work is subsequently used to analyze the CVD of single and polycrystalline diamond films and TiN coatings. The results of the analysis show that the multi-length scale model enables establishment of the relationships between the process parameters, and the properties and performance of the deposited films and coatings. |
