What is the Core Material for SiC Growth ?

In the preparation of high-quality and high-yield silicon carbide substrates, the core requires precise control of production temperature by good thermal field materials. Currently, the thermal field crucible kits mainly used are high-purity graphite structural components, whose functions are to heat molten carbon powder and silicon powder as well as to maintain heat. Graphite materials have the characteristics of high specific strength and specific modulus, good thermal shock resistance and corrosion resistance, etc. However, they have disadvantages such as easy oxidation in high-temperature oxygen-rich environments, poor ammonia resistance and poor scratch resistance. In the growth of silicon carbide single crystals and the production of silicon carbide epitaxial wafers, they are difficult to meet the increasingly strict usage requirements for graphite materials, which seriously restricts their development and practical application. Therefore, high-temperature coatings such as tantalum carbide began to rise.

TaC ceramics have a melting point as high as 3880℃, featuring high hardness (Mohs hardness 9-10), a relatively large thermal conductivity (22W·m-1·K−1), a considerable flexural strength (340-400 mpa), and a relatively small coefficient of thermal expansion (6.6×10−6K−1). They also exhibit excellent thermal chemical stability and outstanding physical properties. TaC coatings have excellent chemical and mechanical compatibility with graphite and C/C composites. Therefore, they are widely used in aerospace thermal protection, single crystal growth, energy electronics, and medical devices, among other fields.

TaC coated graphite has better chemical corrosion resistance than bare graphite or SiC coated graphite. It can be stably used at a high temperature of 2600° C and does not react with many metal elements. It is the best-performing coating in the scenarios of single-crystal growth and wafer etching of third-generation semiconductors, and can significantly improve the control of temperature and impurities in the process. Prepare high-quality silicon carbide wafers and related epitaxial wafers. It is particularly suitable for growing GaN or AlN single crystals on MOCVD equipment and SiC single crystals on PVT equipment, and the quality of the grown single crystals has been significantly improved.