Showa Denko K.K. concluded a long-term supply contract with Toshiba Electronic Devices & Storage Corporation (Toshiba), a Japanese electronic device manufacturer providing highly efficient SiC-power-semiconductor based power devices for the global market, to supply SiC epitaxial wafers for power semiconductors (SiC epi-wafers) for two and a half years with an optional extension clause.
Toshiba has been developing and commercializing various kinds of SiC-based power devices including inverters for railcars, while adopting SiC epi-wafers manufactured by SDK as main material for SiC-based schottky barrier diode (SiC SBD) and SiC-based metal-oxide-semiconductor field-effect transistor (SiC MOSFET).
Toshiba decided to conclude this long-term contract because the company appreciated homogeneity in properties and low density of surface defects of SiC epi-wafers manufactured by SDK. This long-term contract will further strengthen technical cooperation between SDK and Toshiba on improvement in performance of SiC epi-wafers. In addition, SDK expects that Toshiba’s adoption of SiC epi-wafers manufactured by SDK will help SDK to expand its SiC epi-wafer business further.
As the largest independent manufacturer of SiC epi-wafers (estimated by SDK), and under a motto of “Best in Class,” the Showa Denko Group will continue coping with rapid expansion of the market for SiC epi-wafers and providing the market with high-performance and highly-reliable products, thereby contributing to the propagation of SiC power semiconductors which save energy with small power loss and less heat generation.
 “Schottky barrier diode” (SBD) is a kind of diode whose structure includes semiconductor-metal junction instead of PN junction. SBDs are suitable for high-speed switching, and are widely used in switched-mode power supplies.
 “Metal-oxide-semiconductor field effect transistor” (MOSFET) is a kind of transistor that functions fast and has precision control. Therefore, MOSFETs are widely used in switched mode power supplies for power electronics, including converters to control voltage and frequency, and inverters.
 “Homogeneity in properties” means that homogeneity in doping of nitrogen which determines physical property of wafer has been achieved. SiC power semiconductor is produced from SiC doped with nitrogen. SiC power semiconductor for high voltage requires homogeneous doping with small amount of nitrogen.
 “Low density of surface defects” means that the wafer has extremely small numbers of surface defects per square centimeter of wafer surface. If a surface defect exists, electricity flows through that surface defect, and the chip cannot be used as power device. On the other hand, SiC power device for large current requires large SiC chip. Therefore, low density of surface defects is necessary for achievement of high yields in production of power devices. SDK’s second generation high-grade SiC epi-wafer (HGE-2G), which is to be supplied for Toshiba, has achieved 1/2 or less density of surface defects compared to that of the first generation product (HGE).