Patents by Inventor Masashi Nakabayashi

Masashi Nakabayashi has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 8901570
    Abstract: Provided is an epitaxial silicon carbide single-crystal substrate in which a silicon carbide epitaxial film having excellent in-plane uniformity of doping density is disposed on a silicon carbide single-crystal substrate having an off angle that is between 1° to 6°. The epitaxial film is grown by repeating a dope layer that is 0.5 ?m or less and a non-dope layer that is 0.1 ?m or less. The dope layer is formed with the ratio of the number of carbon atoms to the number of silicon atoms (C/Si ratio) in a material gas being 1.5 to 2.0, and the non-dope layer is formed with the C/Si ratio being 0.5 or more but less than 1.5. The resulting epitaxial silicon carbide single-crystal substrate comprises a high-quality silicon carbide epitaxial film, which has excellent in-plane uniformity of doping density, on a silicon carbide single-crystal substrate having a small off angle.
    Type: Grant
    Filed: May 10, 2011
    Date of Patent: December 2, 2014
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Takashi Aigo, Hiroshi Tsuge, Taizo Hoshino, Tatsuo Fujimoto, Masakazu Katsuno, Masashi Nakabayashi, Hirokatsu Yashiro
  • Patent number: 8795624
    Abstract: Provided is a monocrystalline silicon carbide ingot containing a dopant element, wherein a maximum concentration of the dopant element is less than 5×1017 atoms/cm3 and the maximum concentration is 50 times or less than that of a minimum concentration of the dopant element. Also provided is a monocrystalline silicon carbide wafer made by cutting and polishing the monocrystalline silicon carbide ingot, wherein a electric resistivity at room temperature of the wafer is 5×103 ?cm or more. Further provided is a method for manufacturing the monocrystalline silicon carbide including growing the monocrystalline silicon carbide on a seed crystal from a sublimation material by a sublimation method. The sublimation material includes a solid material containing a dopant element, and the specific surface of the solid material containing the dopant element is 0.5 m2/g or less.
    Type: Grant
    Filed: October 5, 2005
    Date of Patent: August 5, 2014
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Masashi Nakabayashi, Tatsuo Fujimoto, Mitsuru Sawamura, Noboru Ohtani
  • Patent number: 8673254
    Abstract: Provided is a monocrystalline silicon carbide ingot containing a dopant element, wherein a maximum concentration of the dopant element is less than 5×1017 atoms/cm3 and the maximum concentration is 50 times or less than that of a minimum concentration of the dopant element. Also provided is a monocrystalline silicon carbide wafer made by cutting and polishing the monocrystalline silicon carbide ingot, wherein a electric resistivity at room temperature of the wafer is 5×103 ?cm or more. Further provided is a method for manufacturing the monocrystalline silicon carbide including growing the monocrystalline silicon carbide on a seed crystal from a sublimation material by a sublimation method. The sublimation material includes a solid material containing a dopant element, and the specific surface of the solid material containing the dopant element is 0.5 m2/g or less.
    Type: Grant
    Filed: March 4, 2011
    Date of Patent: March 18, 2014
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Masashi Nakabayashi, Tatsuo Fujimoto, Mitsuru Sawamura, Noboru Ohtani
  • Patent number: 8491719
    Abstract: The present invention provides a high resistivity, high quality, large size SiC single crystal, SiC single crystal wafer, and method of production of the same, that is, a silicon carbide single crystal containing uncompensated impurities in an atomic number density of 1×1015/cm3 or more and containing vanadium in an amount less than said uncompensated impurity concentration, silicon carbide single crystal wafer obtained by processing and polishing the silicon carbide single crystal and having an electrical resistivity at room temperature of 5×103 ?cm or more, and a method of production of a silicon carbide single crystal.
    Type: Grant
    Filed: May 29, 2009
    Date of Patent: July 23, 2013
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Masashi Nakabayashi, Tatsuo Fujimoto, Mitsuru Sawamura, Noboru Ohtani
  • Publication number: 20130049014
    Abstract: Provided is an epitaxial silicon carbide single-crystal substrate in which a silicon carbide epitaxial film having excellent in-plane uniformity of doping density is disposed on a silicon carbide single-crystal substrate having an off angle that is between 1° to 6°. The epitaxial film is grown by repeating a dope layer that is 0.5 ?m or less and a non-dope layer that is 0.1 ?m or less. The dope layer is formed with the ratio of the number of carbon atoms to the number of silicon atoms (C/Si ratio) in a material gas being 1.5 to 2.0, and the non-dope layer is formed with the C/Si ratio being 0.5 or more but less than 1.5. The resulting epitaxial silicon carbide single-crystal substrate comprises a high-quality silicon carbide epitaxial film, which has excellent in-plane uniformity of doping density, on a silicon carbide single-crystal substrate having a small off angle.
    Type: Application
    Filed: May 10, 2011
    Publication date: February 28, 2013
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Takashi Aigo, Hiroshi Tsuge, Taizo Hoshino, Tatsuo Fujimoto, Masakazu Katsuno, Masashi Nakabayashi, Hirokatsu Yashiro
  • Publication number: 20130029158
    Abstract: Disclosed is a process for producing an epitaxial single-crystal silicon carbide substrate by epitaxially growing a silicon carbide film on a single-crystal silicon carbide substrate by chemical vapor deposition. The step of crystal growth in the process comprises a main crystal growth step, which mainly occupies the period of epitaxial growth, and a secondary crystal growth step, in which the growth temperature is switched between a set growth temperature (T0) and a set growth temperature (T2) which are respectively lower and higher than a growth temperature (T1) used in the main crystal growth step. The basal plane dislocations of the single-crystal silicon carbide substrate are inhibited from being transferred to the epitaxial film. Thus, a high-quality epitaxial film is formed.
    Type: Application
    Filed: April 7, 2011
    Publication date: January 31, 2013
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Takashi Aigo, Hiroshi Tsuge, Taizo Hoshino, Tatsuo Fujimoto, Masakazu Katsuno, Masashi Nakabayashi, Hirokatsu Yashiro
  • Patent number: 8178389
    Abstract: Provided is a monocrystalline silicon carbide ingot containing a dopant element, wherein a maximum concentration of the dopant element is less than 5×1017 atoms/cm3 and the maximum concentration is 50 times or less than that of a minimum concentration of the dopant element. Also provided is a monocrystalline silicon carbide wafer made by cutting and polishing the monocrystalline silicon carbide ingot, wherein a electric resistivity at room temperature of the wafer is 5×103 ?cm or more. Further provided is a method for manufacturing the monocrystalline silicon carbide including growing the monocrystalline silicon carbide on a seed crystal from a sublimation material by a sublimation method. The sublimation material includes a solid material containing a dopant element, and the specific surface of the solid material containing the dopant element is 0.5 m2/g or less.
    Type: Grant
    Filed: February 18, 2010
    Date of Patent: May 15, 2012
    Assignee: Nippon Steel Corporation
    Inventors: Masashi Nakabayashi, Tatsuo Fujimoto, Mitsuru Sawamura, Noboru Ohtani
  • Publication number: 20110308449
    Abstract: The present invention, which provides a crucible for producing single-crystal silicon carbide, and a production apparatus and a production method for single-crystal silicon carbide, which are capable of stably growing a single-crystal silicon carbide ingot good in crystallinity at high yield, is a crucible for producing single-crystal silicon carbide having a crucible vessel for holding silicon carbide raw material and a crucible cover for attaching a seed crystal and is adapted to sublimate a silicon carbide raw material in the crucible vessel to supply silicon carbide sublimation gas onto a seed crystal attached to the crucible cover and grow single-crystal silicon carbide on the seed crystal, which crucible for producing single-crystal silicon carbide is provided in the crucible vessel and the crucible cover with threaded portions to be screwed together and is provided with a sublimation gas discharge groove or grooves capable of regulating flow rate by relative rotation of the threaded portions; and is a
    Type: Application
    Filed: February 25, 2010
    Publication date: December 22, 2011
    Inventors: Masakazu Katsuno, Tatsuo Fujimoto, Hiroshi Tsuge, Masashi Nakabayashi
  • Publication number: 20110278596
    Abstract: The present invention provides an epitaxial SiC monocrystalline substrate having a high quality epitaxial film suppressed in occurrence of step bunching in epitaxial growth using a substrate with an off angle of 6° or less and a method of production of the same, that is, an epitaxial silicon carbide monocrystalline substrate comprised of a silicon carbide monocrystalline substrate with an off angle of 6° or less on which a silicon carbide monocrystalline thin film is formed, the epitaxial silicon carbide monocrystalline substrate characterized in that the silicon carbide monocrystalline thin film has a surface with a surface roughness (Ra value) of 0.5 nm or less and a method of production of the same.
    Type: Application
    Filed: January 29, 2010
    Publication date: November 17, 2011
    Inventors: Takashi Aigo, Hiroshi Tsuge, Taizo Hoshino, Tatsuo Fujimoto, Masakasu Katsuno, Masashi Nakabayashi, Hirokatsu Yashiro
  • Patent number: 8044408
    Abstract: The invention provides a high-quality SiC single-crystal substrate, a seed crystal for producing the high-quality SiC single-crystal substrate, and a method of producing the high-quality SiC single-crystal substrate, which enable improvement of device yield and stability. Provided is an SiC single-crystal substrate wherein, when the SiC single-crystal substrate is divided into 5-mm square regions, such regions in which dislocation pairs or dislocation rows having intervals between their dislocation end positions of 5 ?m or less are present among the dislocations that have ends at the substrate surface account for 50% or less of all such regions within the substrate surface and the dislocation density in the substrate of dislocations other than the dislocation pairs or dislocation is 8,000/cm2.
    Type: Grant
    Filed: May 20, 2009
    Date of Patent: October 25, 2011
    Assignee: Nippon Steel Corporation
    Inventors: Tatsuo Fujimoto, Kohei Tatsumi, Taizo Hoshino, Masakazu Katsuno, Noboru Ohtani, Masashi Nakabayashi, Hiroshi Tsuge, Housei Hirano, Hirokatsu Yashiro
  • Publication number: 20110206929
    Abstract: The present invention provides single-crystal silicon carbide and a single-crystal silicon carbide wafer of good-quality that are low in dislocations, micropipes and other crystal defects and enable high yield and high performance when applied to a device, wherein the ratio of doping element concentrations on opposite sides in the direction of crystal growth of the interface between the seed crystal and the grown crystal is 5 or less and the doping element concentration of the grown crystal in the vicinity of the seed crystal is 2×1019 cm?3 to 6×1020 cm?3.
    Type: Application
    Filed: October 14, 2009
    Publication date: August 25, 2011
    Inventors: Masashi Nakabayashi, Tatsuo Fujimoto, Masakazu Katsuno, Hiroshi Tsuge
  • Publication number: 20110180765
    Abstract: Provided is a monocrystalline silicon carbide ingot containing a dopant element, wherein a maximum concentration of the dopant element is less than 5×1017 atoms/cm3 and the maximum concentration is 50 times or less than that of a minimum concentration of the dopant element. Also provided is a monocrystalline silicon carbide wafer made by cutting and polishing the monocrystalline silicon carbide ingot, wherein a electric resistivity at room temperature of the wafer is 5×103 ?cm or more. Further provided is a method for manufacturing the monocrystalline silicon carbide including growing the monocrystalline silicon carbide on a seed crystal from a sublimation material by a sublimation method. The sublimation material includes a solid material containing a dopant element, and the specific surface of the solid material containing the dopant element is 0.5 m2/g or less.
    Type: Application
    Filed: March 4, 2011
    Publication date: July 28, 2011
    Inventors: Masashi Nakabayashi, Tatsuo Fujimoto, Mitsuru Sawamura, Noboru Ohtani
  • Patent number: 7972704
    Abstract: The present invention provides a single-crystal silicon carbide ingot capable of providing a good-quality substrate low in dislocation defects, and a substrate and epitaxial wafer obtained therefrom. It is a single-crystal silicon carbide ingot comprising single-crystal silicon carbide which contains donor-type impurity at a concentration of 2×1018 cm?3 to 6×1020 cm?3 and acceptor-type impurity at a concentration of 1×1018 cm?3 to 5.99×1020 cm?3 and wherein the concentration of the donor-type impurity is greater than the concentration of the acceptor-type impurity and the difference is 1×1018 cm?3 to 5.99×1020 cm?3, and a substrate and epitaxial wafer obtained therefrom.
    Type: Grant
    Filed: January 14, 2009
    Date of Patent: July 5, 2011
    Assignee: Nippon Steel Corporation
    Inventors: Noboru Ohtani, Masakazu Katsuno, Hiroshi Tsuge, Masashi Nakabayashi, Tatsuo Fujimoto
  • Publication number: 20100295059
    Abstract: The invention provides a high-quality SiC single-crystal substrate, a seed crystal for producing the high-quality SiC single-crystal substrate, and a method of producing the high-quality SiC single-crystal substrate, which enable improvement of device yield and stability. Provided is an SiC single-crystal substrate wherein, when the SiC single-crystal substrate is divided into 5-mm square regions, such regions in which dislocation pairs or dislocation rows having intervals between their dislocation end positions of 5 ?m or less are present among the dislocations that have ends at the substrate surface account for 50% or less of all such regions within the substrate surface and the dislocation density in the substrate of dislocations other than the dislocation pairs or dislocation is 8,000/cm2.
    Type: Application
    Filed: May 20, 2009
    Publication date: November 25, 2010
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Tatsuo FUJIMOTO, Kohei TATSUMI, Taizo HOSHINO, Masakazu KATSUNO, Noboru OHTANI, Masashi NAKABAYASHI, Hiroshi TSUGE, Housei HIRANO, Hirokatsu YASHIRO
  • Publication number: 20100289033
    Abstract: The present invention provides a single-crystal silicon carbide ingot capable of providing a good-quality substrate low in dislocation defects, and a substrate and epitaxial wafer obtained therefrom. It is a single-crystal silicon carbide ingot comprising single-crystal silicon carbide which contains donor-type impurity at a concentration of 2×1018 cm?3 to 6×1020 cm3 and acceptor-type impurity at a concentration of 1×1018 cm?3 to 5.99×1020 cm?3 and wherein the concentration of the donor-type impurity is greater than the concentration of the acceptor-type impurity and the difference is 1×1018 cm?3 to 5.99×1020 cm?3, and a substrate and epitaxial wafer obtained therefrom.
    Type: Application
    Filed: January 14, 2009
    Publication date: November 18, 2010
    Inventors: Noboru Ohtani, Masakazu Katsuno, Hiroshi Tsuge, Masashi Nakabayashi, Tatsuo Fujimoto
  • Patent number: 7799305
    Abstract: The present invention provides a semi-insulating silicon carbide single crystal characterized by having an electrical resistivity at room temperature of 1×105 ?cm or more, and a semi-insulating silicon carbide single crystal characterized by having an electrical resistivity at room temperature of 1×105 ?cm or more and vacancy pairs (bivacancies), and an semi-insulating silicon carbide single crystal characterized by having an electrical resistivity at room temperature of 1×105 ?cm or more and containing a crystal region where a position average lifetime becomes a lifetime longer than 155 ps in measurement of position lifetime at a liquid nitrogen boiling point temperature (77K) or less, and wafer obtained therefrom.
    Type: Grant
    Filed: June 15, 2005
    Date of Patent: September 21, 2010
    Assignee: Nippon Steel Corporation
    Inventors: Mitsuru Sawamura, Tatsuo Fujimoto, Noboru Ohtani, Masashi Nakabayashi
  • Patent number: 7794842
    Abstract: The present invention provides a high resistivity, high quality, large size SiC single crystal, SiC single crystal wafer, and method of production of the same, that is, a silicon carbide single crystal containing uncompensated impurities in an atomic number density of 1 ×1015/cm3 or more and containing vanadium in an amount less than said uncompensated impurity concentration, silicon carbide single crystal wafer obtained by processing and polishing the silicon carbide single crystal and having an electrical resistivity at room temperature of 5×103 ?cm or more, and a method of production of a silicon carbide single crystal.
    Type: Grant
    Filed: December 27, 2004
    Date of Patent: September 14, 2010
    Assignee: Nippon Steel Corporation
    Inventors: Masashi Nakabayashi, Tatsuo Fujimoto, Mitsuru Sawamura, Noboru Ohtani
  • Publication number: 20100147212
    Abstract: Provided is a monocrystalline silicon carbide ingot containing a dopant element, wherein a maximum concentration of the dopant element is less than 5×1017 atoms/cm3 and the maximum concentration is 50 times or less than that of a minimum concentration of the dopant element. Also provided is a monocrystalline silicon carbide wafer made by cutting and polishing the monocrystalline silicon carbide ingot, wherein a electric resistivity at room temperature of the wafer is 5×103 ?cm or more. Further provided is a method for manufacturing the monocrystalline silicon carbide including growing the monocrystalline silicon carbide on a seed crystal from a sublimation material by a sublimation method. The sublimation material includes a solid material containing a dopant element, and the specific surface of the solid material containing the dopant element is 0.5 m2/g or less.
    Type: Application
    Filed: February 18, 2010
    Publication date: June 17, 2010
    Inventors: Masashi NAKABAYASHI, Tatsuo FUJIMOTO, Mitsuru SAWAMURA, Noboru OHTANI
  • Publication number: 20100080956
    Abstract: The invention provides a low resistivity silicon carbide single crystal wafer for fabricating semiconductor devices having excellent characteristics. The low resistivity silicon carbide single crystal wafer has a specific volume resistance of 0.001 ?cm to 0.012 ?cm and 90% or greater of the entire wafer surface area is covered by an SiC single crystal surface of a roughness (Ra) of 1.0 nm or less.
    Type: Application
    Filed: December 1, 2009
    Publication date: April 1, 2010
    Inventors: Tatsuo Fujimoto, Noboru Ohtani, Masakazu Katsuno, Masashi Nakabayashi, Hirokatsu Yashiro
  • Publication number: 20090255458
    Abstract: The present invention provides a high resistivity, high quality, large size SiC single crystal, SiC single crystal wafer, and method of production of the same, that is, a silicon carbide single crystal containing uncompensated impurities in an atomic number density of 1×1015/cm3 or more and containing vanadium in an amount less than said uncompensated impurity concentration, silicon carbide single crystal wafer obtained by processing and polishing the silicon carbide single crystal and having an electrical resistivity at room temperature of 5×103 ?cm or more, and a method of production of a silicon carbide single crystal.
    Type: Application
    Filed: May 29, 2009
    Publication date: October 15, 2009
    Applicant: Nippon Steel Corporation
    Inventors: Masashi Nakabayashi, Tatsuo Fujimoto, Mitsuru Sawamura, Noboru Ohtani