Numerical simulation of thermal and microdefect distributions effected by different types of heat shields during the Czochralski silicon crystal growth

The present study makes use of the continuity equation, the Navier-Stokes equation, the energy equation and the defect equation to analyze Czochralski silicon crystal growth. We study the effects of the heat shield shape on the temperature and velocity distribution in the furnace, as well as on the axial temperature gradient and defect distribution in the crystal. The installation of the heat shield changes the temperature distribution and the fluid field of the furnace. Consequently the quality of the crystal is improved because microdefects are reduced, and the growth rate of the crystal increased. Moreover, a heat shield also helps the argon gas to carry SiO out of the furnace. The present study also discusses the influence of the shape at the heat shield on the argon gas flow velocity distribution in the furnace. The ability of different heat shields to carry SiO out of the furnace is different. A new type heat shield, which improves the thermal and velocity fields during Czochralski silicon crystal growth, to obtain a better quality silicon crystal is proposed.