Furnace components for Crystal Growth

SiC wafers with high voltage resistance are used as materials (wafers) for power semiconductors instead of conventional Si wafers. The crystal growth temperature in the sublimation process for SiC ingot production is extremely high at about 2,500°C. Therefore, graphite with excellent heat resistance is used for the internal furnace components. In addition, some components are required to have the same dimensional change as that of single crystal SiC under high temperature.　Graphite with a low coefficient of linear thermal expansion (dimensional change with temperature) is used for some components. Since the sublimation method uses a large amount of graphite, it is essential to establish a stable supply system. We can produce graphite materials of stable quality, which has been cultivated through the supply of monocrystalline silicon production components. In many cases, monocrystalline SiC is produced overseas, and Toyo Tanso, which has processing and high-purity facilities at its major bases, can respond to the global supply chain.

Susceptor for Epitazial Growth Equipment Componets

SiC epitaxial growth, a monocrystalline SiC wafer is mounted on a susceptor (SiC/TaC coated graphite material) and placed in an epitaxial furnace at approximately 1600°C. The monocrystalline SiC thin film is grown in the vapor phase on the surface of the monocrystalline SiC wafer by heating the wafer to approximately 1600°C and passing vaporized raw material gas through the furnace. The challenges for single crystal SiC wafers include reducing crystal defects, improving yield and increasing diameter. Since it is difficult to reduce crystal defects in the crystal growth process, a film with fewer crystal defects is formed by epitaxial growth. Since the deposition temperature is very high at about 1600°C and particles from the graphite substrate are undesirable, a coated graphite member is used. The optimal coating material for the graphite material, such as SiC or TaC (tantalum carbide), is selected according to the environment and conditions in which it will be used.

Typical products for SiC semiconductor applications include PERMA-KOTE®, an SiC coated graphite material in which SiC (silicon carbide) is CVD coated onto an isotropic graphite surface, and EVEREDKOTE®-B, a TaC (tantalum carbide) coated graphite material in which dense tantalum carbide is CVD coated onto a high purity isotropic graphite base material.