(Invited) Investigation on the Carbon Supply in the Top Seeded Solution Growth of SiC Bulk Crystal

Abstract

Top Seeded Solution Growth (TSSG) method is assumed to be a promising bulk growth technique for high quality SiC substrate. Generally, the sources of Si and C in the TSSG method are Si chunk and Graphite crucible, respectively. The crystal growth through TSSG method is achieved by the precipitation of solid SiC from C dissolved a Si melt on a seed crystal located at the top of the liquid. The C solubility in pure Si liquid is extremely low, so that metallic solvents such as Cr, Ti and Fe were added to increase the C solubility in Si liquid. Consequently, the growth rate of SiC crystal through the TSSG method has been reached up to 2 mm/hour. However, as increasing C solubility, the loss of the graphite crucible became another critical issue. Because the C source in the TSSG method is the graphite crucible, the reservoir of Si liquid, the increase of C solubility means the decrease of the crucible durability. The graphite crucible durability influences not only on the thickness of the grown crystal, but also on the temperature distribution in the reactor.In this study, we introduce our recent progress on the carbon supply in the TSSG method to produce a reliable long-term growth technique. The interface between graphite crucible and Si liquid was first studied from point of thermodynamics. Considering the reaction between graphite crucible and Si liquid, several crucible structures with different materials and designs were suggested for the improvement of TSSG method based on theoretical understanding.