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Advanced Power Electronics Research Center

Wafer Process Team

Overview of Research

 This team carries out research aimed at the development of technology from 4H-SiC crystal growth to epitaxial film growth and optimization, as well as cost reduction, increasing performance, increasing quality, and handling large-size crystals. In addition, this team is responsible for research under the Ministry of Economy, Trade and Industry’s “New Material Power Semiconductor Project for Achieving a Low-Carbon Society ” and the “Innovative Silicon Carbide Power Electronics Research for Creating a Low-Carbon Society ,” which is part of the Funding Program for Next Generation World-Leading Researchers (NEXT Program ).


FIG. 1  4H-SiC bulk single crystal and large sublimation furnace

 Large scale sublimation furnace used to grow SiC single crystals and a crystal that has been grown are shown in FIG 1. We are carrying out development of technology for growing large, high-quality 4H-SiC single crystals using sublimation techniques; development of technology for growing single crystals of 4H-SiC from the liquid phase, and development of technology for growing single crystals of AlN using sublimation techniques.
大型昇華炉と成長させた4H-SiCバルク単結晶
FIG. 1  4H-SiC bulk single crystal and large sublimation furnace

FIG. 2  Example of high-performance, high-quality slicing of a 4H-SiC single crystal by using electrical discharge machining

 FIG. 2 shows examples of slicing a 4H-SiC single crystal by electrical discharge machining. This team is developing rapid, highly accurate, low cost, and environmentally friendly technologies for finishing single crystals of SiC, which is almost as hard as diamond, into wafer form by slicing, processing, and polishing the material.

FIG. 2  Example of high-performance, high-quality slicing of a 4H-SiC single crystal by using electrical discharge machining

FIG. 3  Research on epitaxial film growth

 FIG. 3 shows equipment for research on epitaxial film growth. Our research has resulted in establishment of new techniques for uniform, high-quality epitaxial film growth on Si surface wafers and C surface wafers, epitaxial film growth on vicinal wafers , and high-speed epitaxial film growth. We are currently developing technologies for large, uniform epitaxial film growth; multilayer thick film growth technology for devices with high blocking voltage ultra-high-speed growth technology; etc.

FIG. 3  Research on epitaxial film growth

FIG. 4  Structure of SiO2/SiC interface

 FIG. 4 shows transmission electron microscope observations of the SiO2/SiC interface. The effects of wafer processes and device processes on crystal quality are being examined using topographic SEM, TEM, PL, CL, EBIC , and topographic method by SCR. This makes a contribution to the development of highly efficient processes that maintain a high level of crystal quality.

FIG. 4  Structure of SiO2/SiC interface


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