Numerical scale-up study of silicon deposition using 2D slit nozzle sources

The scale-up of a silicon film deposition process employing supersonic molecular beams of Si2H6/H2 mixture is investigated using the direct simulation Monte Carlo method in the transition regime. Previous studies employing an orifice/skimmer configuration revealed great success in modeling this process of film growth for deposition on a small scale. The present study considers a two dimensional slit nozzle to deposit epitaxial thin films over a larger area. The precursor incident flux, kinetic energy and angle are calculated and incorporated into the silicon film growth rate numerically. The effects of several key physical parameters are addressed. It is found that a 2D source has a smaller expansion ratio and generates a high back pressure that induces excessive molecular scattering and prevents disilane molecules from obtaining high impact energy over the substrate. The surface sticking probability is severely reduced compared with the previous axisymmetric simulations. Flow conditions suitable for film growth are suggested. The multiple slit nozzle sources are found applicable to improve the uniformity of the reactant incident flux and the film growth rate.