Patents by Inventor Hirokatsu Yashiro

Hirokatsu Yashiro 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: 9915011
    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: Grant
    Filed: December 1, 2009
    Date of Patent: March 13, 2018
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Tatsuo Fujimoto, Noboru Ohtani, Masakazu Katsuno, Masashi Nakabayashi, Hirokatsu Yashiro
  • Patent number: 9691607
    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: Grant
    Filed: April 7, 2011
    Date of Patent: June 27, 2017
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Takashi Aigo, Hiroshi Tsuge, Taizo Hoshino, Tatsuo Fujimoto, Masakazu Katsuno, Masashi Nakabayashi, Hirokatsu Yashiro
  • Publication number: 20150075422
    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: November 19, 2014
    Publication date: March 19, 2015
    Inventors: Takashi Aigo, Hiroshi Tsuge, Taizo Hoshino, Tatsuo Fujimoto, Masakasu Katsuno, Masashi Nakabayashi, Hirokatsu Yashiro
  • Patent number: 8927396
    Abstract: An object of the present invention is to provide a production process of an epitaxial silicon carbide single crystal substrate having a high-quality silicon carbide single crystal thin film reduced in the surface defect and the like on a silicon carbide single crystal substrate with a small off-angle. According to the present invention, in the production process of an epitaxial silicon carbide single crystal substrate having a high-quality silicon carbide single crystal thin film reduced in the surface defect and the like on a silicon carbide single crystal substrate with an off-angle of 4° or less, pretreatment etching to a depth of 0.1 to 1 ?m is performed at a temperature of 1,550 to 1,650° C. by flowing a gas containing silicon and chlorine together with a hydrogen gas such that the silicon atom concentration becomes from 0.0001 to 0.01% based on hydrogen atoms in the hydrogen gas, and thereafter, an epitaxial layer is formed.
    Type: Grant
    Filed: November 15, 2011
    Date of Patent: January 6, 2015
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Takashi Aigo, Hiroshi Tsuge, Masakazu Katsuno, Tatsuo Fujimoto, Hirokatsu Yashiro
  • 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: 8707944
    Abstract: A saw wire includes a steel wire (11) having a steel strand (11a) with predetermined composition, an abrasive (13) fixed to the steel wire (11) by a fixing part (12), and an intermetallic compound (15) on an interface between the abrasive (13) and the fixing part (12). Tensile strength of the steel strand (11) is 3500 MPa or more, and the fixing part (12) includes a Sn-based solder containing Zn or Ag.
    Type: Grant
    Filed: June 14, 2011
    Date of Patent: April 29, 2014
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Mitsuru Morita, Toshimi Tarui, Hiroaki Sakamoto, Hirokatsu Yashiro, Makoto Kosaka
  • Publication number: 20130320357
    Abstract: Provided are an epitaxial silicon carbide single crystal substrate having a high-quality silicon carbide single crystal thin film with less stacking faults on a silicon carbide single crystal substrate and a production method therefor. The epitaxial silicon carbide single crystal substrate is produced by growing a silicon carbide epitaxial layer on a silicon carbide single crystal substrate having an off-angle of 4° or less so that the number of stacking faults emitting light at wavelengths ranging from 400 to 600 nm by photoluminescence on the substrate is less than 10/cm2 in total. Additionally, the method for producing the epitaxial silicon carbide single crystal substrate forms the epitaxial layer by using chlorosilane as a silicon-based material gas and hydrocarbon gas as a carbon-based gas, at a growth temperature of 1600° C. to 1700° C., at a C/Si ratio of 0.5 to 1.0, and at a growth rate of 1 to 3 ?m/hr.
    Type: Application
    Filed: April 20, 2012
    Publication date: December 5, 2013
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Takashi Aigo, Hiroshi Tsuge, Masakazu Katsuno, Tatsuo Fujimoto, Hirokatsu Yashiro, Wataru Ito
  • Publication number: 20130217213
    Abstract: An object of the present invention is to provide a production process of an epitaxial silicon carbide single crystal substrate having a high-quality silicon carbide single crystal thin film reduced in the surface defect and the like on a silicon carbide single crystal substrate with a small off-angle. According to the present invention, in the production process of an epitaxial silicon carbide single crystal substrate having a high-quality silicon carbide single crystal thin film reduced in the surface defect and the like on a silicon carbide single crystal substrate with an off-angle of 4° or less, pretreatment etching to a depth of 0.1 to 1 ?m is performed at a temperature of 1,550 to 1,650° C. by flowing a gas containing silicon and chlorine together with a hydrogen gas such that the silicon atom concentration becomes from 0.0001 to 0.01% based on hydrogen atoms in the hydrogen gas, and thereafter, an epitaxial layer is formed.
    Type: Application
    Filed: November 15, 2011
    Publication date: August 22, 2013
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Takashi Aigo, Hiroshi Tsuge, Masakazu Katsuno, Tatsuo Fujimoto, Hirokatsu Yashiro
  • 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
  • Publication number: 20120216787
    Abstract: A saw wire includes a steel wire (11) having a steel strand (11a) with predetermined composition, an abrasive (13) fixed to the steel wire (11) by a fixing part (12), and an intermetallic compound (15) on an interface between the abrasive (13) and the fixing part (12). Tensile strength of the steel strand (11) is 3500 MPa or more, and the fixing part (12) includes a Sn-based solder containing Zn or Ag.
    Type: Application
    Filed: June 14, 2011
    Publication date: August 30, 2012
    Inventors: Mitsuru Morita, Toshimi Tarui, Hiroaki Sakamoto, Hirokatsu Yashiro, Makoto Kosaka
  • 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: 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: 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
  • Patent number: 5017018
    Abstract: A clinical thermometer which employs an infrared sensor and is constructed so as to prevent the occurrence of a temperature measurement error caused by a change in temperature of a tip portion (of a housing a temperature measuring portion) during temperature measurement. In one embodiment a heat insulator is attached to the tip portion to prevent a rise in temperature of the tip portion. In a second embodiment, the tip portion is formed of a metal of good heat conductivity in the shape of a net for example to improve the heat radiating property of the tip portion, thereby preventing a rise in temperature of the tip portion. In a third embodiments, a temperature sensor is attached to the tip portion to correct a temperature measurement error caused by a change in temperature of the tip portion.
    Type: Grant
    Filed: August 18, 1989
    Date of Patent: May 21, 1991
    Assignee: Nippon Steel Corporation
    Inventors: Tohru Iuchi, Yukio Nakamori, Atsushi Kawasaki, HIrokatsu Yashiro, Yoh-ichi Nagatake
  • Patent number: 4912987
    Abstract: For measuring the sizes of particles in the falling state, electromagnetic waves having different frequencies are transmitted from a transmitter/receiver onto the particles in the falling state and reflected electromagnetic waves having different frequencies reflected from the particles in the falling state are received by the transmitter/receiver. Data of the distribution of sizes of the particles and the average size of the particles are derived from the detected intensities of the received reflected electromagnetic waves.
    Type: Grant
    Filed: March 2, 1989
    Date of Patent: April 3, 1990
    Assignee: Nippon Steel Corporation
    Inventors: Hirokatsu Yashiro, Jiro Ohno, Yoshiteru Matsuo, Hiroshi Nishikawa, Katsuhiko Yui, Hirotoshi Kawamura
  • Patent number: 4843894
    Abstract: For measuring the sizes of particles in the falling state, electromagnetic waves having different frequencies are transmitted from a transmitter/receiver onto the particles in the falling state and reflected electromagnetic waves having different frequencies reflected from the particles in the falling state and received by the transmitter/receiver. Data of the distribution of sizes of the particles and the average size of the particles are derived from the detected intensities of the received reflected electromagnetic waves.
    Type: Grant
    Filed: September 14, 1987
    Date of Patent: July 4, 1989
    Assignee: Nippon Steel Corporation
    Inventors: Hirokatsu Yashiro, Jiro Ohno, Yoshiteru Matsuo, Hiroshi Nishikawa, Katsuhiko Yui, Hirotoshi Kawamura
  • Patent number: 4641083
    Abstract: A method and apparatus for supervising a descending speed, thickness of a layer, particle size, and so on of charges in a blast furnace. Coke and ore composing the charges are detected by radiating an electromagnetic wave into the blast furnace. An electromagnetic wave can easily pass through coke, but is reflected or scattered by ore.
    Type: Grant
    Filed: August 1, 1983
    Date of Patent: February 3, 1987
    Assignee: Nippon Steel Corporation
    Inventors: Jiro Ohno, Hirokatsu Yashiro
  • Patent number: 4641036
    Abstract: A method of imaging the surface of an object at high temperature includes the steps of: irradiating the surface of a high-temperature object with two different kinds of pulses of monochromatic light of a fundamental wave and a harmonic thereof; passing the reflected light from the surface of the object through both an interference filter which allows only the two different kinds of monochromatic light to pass and a high-speed optical switch thereby to remove any background light component; drawing out only the reflected light of the pulses and leading the same to an image generating mechanism where it is converted into an image; and controlling the voltage applied to the high-speed optical switch thereby to adjust the mixing ratio between two wavelengths.
    Type: Grant
    Filed: September 21, 1984
    Date of Patent: February 3, 1987
    Assignee: Nippon Steel Corporation
    Inventors: Jiro Ohno, Hirokatsu Yashiro