Simulation of Heat Transfer in a Vertical Tubular CVD Reactor

Polysilicon growth has increased due to its broad applications and market demand. The traditional method for polysilicon growth is based on the Siemens process. To improve the throughput, a new system with either large growth surface or other mechanism for high deposition rate is necessary. A novel design, using a vertical tubular CVD reactor has been recently proposed, in which an enlarged surface reaction area exits. This study is to investigate the optimal conditions for growth through numerical simulation of heat and mass transfer in the proposed vertical tubular CVD reactor. A complex computational model is developed that is capable of describing multi-component fluid flow, gas/surface chemistry, conjugate heat transfer, thermal radiation, and species transport. Different from the classical Siemens system, the bulk poly-silicon in a vertical tube growth has a complicated geometry. To accurately predict the various parameters covering broad range of scales, a multi-block grid generation system is used. Numerical computation has been conducted under different operating conditions, and in particular the effect of cooling gas flow direction and flow rate on the temperature distribution of the system and the polysilicon deposition rate has been investigated. Numerical results show that cooling from the top of the system is preferred.