CVD in Weakly Rarefied Rotating Disk Flows

摘要

CVD in a weakly rarefied rotating disk flow is numerically investigated using the SPIN code modified by including slip boundary conditions for velocity, concentration, and temperature, and thereby extending the capability of the code to describe weakly rarefied flows. A model reaction mechanism for silicon deposition, including the gas-phase decomposition of silane to silylene and the surface reactions of silane and silylene, is used in order to demonstrate rarefied gas effects. Results show that, by taking into account the temperature slip, the deposition rate decreases from its value based on the continuum model, mainly due to either the decrease of the concentration of silylene, which is the dominant deposition species at high temperatures, or the decrease of the sticking coefficient of silane, which is the dominant deposition species at low temperatures. Compared to that of the temperature slip, the influence on the deposition rate of the velocity and concentration slips is negligible.