Convection-assisted chemical vapor deposition (CoCVD) of silicon on large-area substrates

Results obtained from a recently completed chemical vapor deposition (CVD) system for the epitaxial growth of silicon layers on rectangular, large-area substrates of up to 43 cm×43 cm are reported.In contrast to conventional CVD systems, buoyancy convection is not suppressed but utilized to assist and stabilize the gas flow. The new method is particularly suited for large-area deposition at atmospheric pressure, as in such regimes the influence of buoyancy convection tends to emerge and must be taken into account.In deposition experiments growth rates of up to 1.2 μm/min were obtained. Parasitic deposition on the reactor walls was not observed. Operation at different tilt angles of the system was applied in order to clarify the influence of buoyancy convection. Tilting of the system, with respect to a horizontal substrate alignment, resulted in an increase of growth rates and also changed their spatial distribution. At optimum angle a spatial uniformity of layer thickness of ±10% was obtained, without any substrate movement. On epitaxial layers etch pit densities of 0.6×103–5×103 cm−2 were obtained.The system was investigated by numerical fluid dynamic simulations. The temperature distribution, the gas flow, and the distribution of growth rates were calculated at different tilt angles. The simulated growth rates are in good agreement with experimental results.