Numerical and experimental evaluations on new direct growth process of polycrystalline silicon wafer from liquid silicon

A new polycrystalline silicon (Si) wafering process directly from Si melt is introduced. As Si is known to have high latent heat, maintaining the steady state solidification condition in target area could be a main issue to achieve proposing wafering process. In addition, as the proposed process is based on horizontal growth, another critical issue is to keep grains growth parallel to the wafer growth direction, which results in large grain sizes. At first, simple numerical modeling was used to evaluate the possibility of realizing this new conceptual process, and to determine the main process parameters. From the simulation results, growth velocity and heat transfer rate at the solidification zone was identified as main process parameters for the steadily grown Si wafer within target area. Based on the simulation results, a growth system was set up experimentally, and the feasibility of the process was examined. A Si wafer with dimensions of 156×156×0.3 mm3 was successively obtained and grains growth parallel to wafer growth direction as calculated in the simulation were observed.