Growth of multicrystalline silicon in a cone-shaped crucible

In this paper, a novel, vertical Bridgman-type technique for growing multicrystalline silicon (mc-Si) ingots in an induction furnace is described. In contrast to conventional growth, a modified setup with a cone-shaped crucible and susceptor is used for the first time. The temperature field and melt flow in the modified setup are calculated numerically and compared with the situation in a cylindrical standard setup. A cone-shaped mc-Si ingot is presented and analyzed with focus on the microstructure (inclusions, dislocations, grains) and the minority carrier lifetime, which are compared with the properties of a cylindrical ingot grown under similar conditions. Results of numerical simulations and growth experiments are discussed with respect to the influence of the cone-shaped setup on the temperature and flow fields in the melt, as well as on the microstructure and the minority carrier lifetime in the crystal. They indicate the potential of the novel technology to produce mc-Si ingots with a globular grain structure, low dislocation density, and high carrier lifetime.