Seed Production and Melt Replenishment for the Czochralski Growth of Silicon Germanium

Abstract

The silicon transport in a silicon germanium melt has been studied to address the issues of melt replenishment and seed production for the Czochralski growth of silicon germanium (SiGe) crystals. The growth of SiGe single crystals by the Czochralski method requires that the melt be replenished with silicon during the growth process due to the rejection of germanium into the melt during solidi cation. To facilitate the replenishment of the melt, an accurate knowledge of the dissolution rate of silicon into the melt and its transport through the melt is required. To address these issues, a number of experiments have been carried out on the dissolution of silicon into a germanium melt. Liquid phase di usion growth experiments were also conducted for insight into transport and as a possible method for seed crystal production. The experiments encompassed various temperatures, crucible geometries, crucible translation, and magnetic eld levels to determine optimum conditions for the most favorable dissolution rates and mass transport in the melt. Results have shown that replenishment from bottom of the crucible is most e ective due to the enhanced silicon transport by buoyancy. The application of magnetic elds may also provide an e ective mean to control the replenishment rate (mass transport rate) in the melt.