News Release

Air Water develops a fabrication technology for the world’s first 8-inch SiC Single Crystal Wafer in conjunction with Osaka Prefecture University.

Dec 10, 2004

Air Water Inc. (AWI) has developed a fabrication technology for an 8-inch single silicon wafer, highlighted as the next generation semiconductor material, using the epitaxial growth method. The technology was developed in conjunction with Osaka Prefecture University and is the first 8 inch silicon carbide (SiC) single crystal wafer ever to be fabricated.Silicon carbide possesses superior physical properties with a band gap three times wider, a dielectric breakdown field ten times higher, thermal conductivity three times higher, and an electron saturation velocity about three times higher than the silicon (Si) semiconductors in current use. Based on these properties, it is anticipated that silicon carbide will be used in the development of a highly heat resistant, ultra low loss semiconductor devise with high speed operational power. This would lead to a major enhancement in electronic circuitry.

The SiC single crystal wafers that have been developed up to now have been bedeviled by micropipe and dislocation defects in the crystal lattice. These were major barriers in the process for the fabrication of the device. In addition, the fabrication technology of the large diameter wafer which was required for improving the efficiency in the process for the fabrication of the device had yet to be created.

The technology now developed by AWI involves growing the SiC single crystal wafer on a silicon-on-wafer (SOI wafer formation) using chemical vapor disposition (CVD). The fabrication process involves the following:

  • Transforming the oxide layer (SiO2) into the Si wafer (SOI wafer formation)
  • Ultra thinning of the the Si layer
  • Formation of the SiC layer
  • Expitaxial growth of the SiC single crystal layer, using the VCE device
  • Among these processes, the AWI proprietary high vacuum epitaxial growth device is used for the formation of the SiC single crystal layer.

    Up to now there have been two main methods for the fabrication of the SiC single crystal wafer, both of which required high temperatures. 2,000℃ as required for the sublimation method and 1,500℃ for the high temperature CVD method. In contrast to these methods, AWI has developed a method which will allow for a large area of single crystal growth at the low temperature of 1,100℃ It is anticipated that this will allow for the low cost fabrication of SiC single crystal wafers, and this will boost the development of new materials. There are still issues to be resolved before this technology can go into practical use. These involve making the single crystal layer thicker, improving the epitaxial growth rate, and achieving uniformity in the thickness of the film.

    Issues still remain before practical application is possible, such as making thick membranes having a single crystal layer, improvement in the speed of the epitaxial growth, and making the thickness of the membrane uniform. The road ahead is basically clear, however. As for prospects for the future, the company plans to persue formation of an integrated device for electron and light fusion on the SiC single crystal wafer by focusing on the compatibility of the SiC single crystal and gallium nitride (GaN). Focus is now on this as the crystallogenic substance for the blue light emission diode.

    Research on the development of the multiple semiconductor wafer for a device which integrates electrons and light was granted a subsidy as an innovative project through the Industry, Academia, Government Collaboration Program (Research Program of the Development of Science and Technology) in 2003, by the Ministry of Education, Culture, Sports, Science, and Technology. Research has been conducted in conjunction with the Research Institute for advanced Science & Technology of Osaka Prefecture University, headed by Professor Akira Mizobata.

    CONTACT: S. Kishi and J. Ishino
    Public Relations, Air Water Inc.
    20-16, Higashi Shinsaibashi 1-chome,
    Chuo-ku, Osaka 542-0083
    Tel: 06-6252-5411 Fax: 06-6252-3965

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