Numerical model of carbon chemical vapor deposition at internal surfaces

The objective of this study is to obtain the rate of Carbon deposition by low pressure chemical vapor deposition process (LPCVD) at internal surfaces to verify that large aspect ratio features can be filled. The mathematical model of LPCVD from reactor-scale to millimeter-scale channels is developed by using Computational Fluid Dynamics software ANSYS/FLUENT. To mimic voids in fibers' structure, the CVD rate is obtained along each drilled channel in the parallelepiped sample hanged along the reactor axis. The role of heating of feedstock gas in reactor is discussed. Numerical modeling shows that vortices are generated near entrances of each channel. These vortices partially block the flow of feedstock gas from entering into the channel. Because of higher growth rate of carbon near the entrances of channels and partial blockage of the flow toward the centers of channels, the centers of channels have less exposure to CVD reactants; therefore, the channels can be blocked before completion of CVD that might create voids in CVD-manufactured materials.