NUMERICAL-SOLUTION OF FREE-BOUNDARY PROBLEMS - CALCULATION OF INTERFACE EVOLUTION DURING CVD GROWTH

A procedure is described for numerical solution of free-boundary probl ems where highly nonlinear boundary shapes develop. A simple explicit solution method is used, and special attention is given to two aspects . The first is the introduction of a parametrization, which stretches the boundary/interface and allows tracing the development of interface shapes beyond the point where a single-valued representation becomes inappropriate. The second is a procedure for automatic generation of a mesh for discretizing the domain above a highly nonlinear interface. Examples of the evolution of a gas-solid interface during solid film g rowth by chemical vapor deposition are used to illustrate application of the solution method. The effect of different values of mesh generat ion parameters on placement of nodes are shown, as well as the effect of the number of nodes along the interface. It was found that in cases with a highly distorted boundary, the shape of the boundary can be us ed in the weight functions to ensure appropriate concentration of node s in groove regions. The number of nodes along the interface is less c rucial than the choice of interface length to be studied. (C) 1996 Aca demic Press, Inc.