Numerical examination and verification of the directional solidification of silicon process

The present study take into account the experimental data for comparison first and numerically investigate the associated parametric influences upon crystal growth process of polysilicon in association with directional solidification. The simulation is via a 2-D time-dependent simulations using the custom software package written in Comsol Multiphysics. The first set of simulation examined the impact of crucible’s heat transfer coefficient, and the results indicate that a large heat transfer coefficient result in faster crystal growth became faster. In addition, radial crystal growth also increased since radial heat loss also became larger. The second case study is carried out about the location of the insulation layer underneath the crucible. The simulation suggests that it could shorten the time on crystal growth while the growth velocity may be too fast to achieve good quality crystal. The third case was conducted concerning the location of insulation block which is located on the side corner of the crucible. The simulation reveals that it could slow down the flow velocity in the crucible on the corner. It also decreased radial crystal growth but casts negligible effects on the overall rate of crystal growth. The fourth one extended heat insulation on the bottom of the crucible. One interesting finding of this simulation is that it can maintain the temperature appreciably and decreased temperature difference on the side crucible, thereby increasing axial temperature gradient. Therefore, this design could attain the lowest figure of merit denoted as Velocity/Gradient value without radial crystal growth. The last design combined third and fourth design. Unexpectedly, the simulation showed that it could not accelerate lateral crystal growth because the fourth design could maintain the temperature and slow down the heat transfer into the crucible. Nonetheless, the third design would block sufficient heat into the crucible. In summary, these results indicate that extending heat insulation block on the bottom of the crucible depicts the best Velocity/Gradient value and configuration shape for melt/crystal interface.