Modeling Of Transport Phenomena In Semiconductor Processing

Two-dimensional predictions of complex gas flows are presented in this work for various chemical vapor deposition (CVD) processes and crystal pulling from a melt system (Czochralski crystal growth). The model used in the calculations involves momentum, energy and mass conservation equations with corresponding boundary conditions. The structure of convective heat and mass transfer has been studied in vertical CVD reactors with emphasis on their effect on non-uniformity in epilayer thickness and composition. Three kind of CVD reactors with various inlet jet directions and wall temperatures have been considered for typical operating conditions. Strong buoyancy-driven recirculations were found near the susceptor edge in all predictions. Another object for the numerical investigation was the mixed convection in the gas region around a crystal for the encapsulated Czochralski growth. The gas flow over a crystal protects its surface from some negative effects such as a solid particle deposition. Different stages of crystal pulling from a melt have been considered and an improved construction for gas inlets/outlets, based on the numerical results, have been proposed.