Patents by Inventor Hiroshi Koya

Hiroshi Koya 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).

  • Publication number: 20040025983
    Abstract: An ingot is manufactured by pulling it up such that V/Ga and V/Gb become 0.23 to 0.50 mm2/minute. ° C., respectively, where V (mm/minute) is a pulling-up speed, and Ga (° C./mm) is an axial temperature gradient at the center of the ingot and Gb (° C./mm) is an axial temperature gradient at the edge of the ingot at temperatures in a range of 1,300° C. to a melting point of silicon. A wafer obtained by slicing the ingot is heat treated in a reductive atmosphere at temperatures in a range of 1,050° C. to 1,220° C. for 30 to 150 minutes. A silicon wafer free of OSF's, tree of COP's, and substantially free of contamination such as Fe and of occurrence of slip, is obtained.
    Type: Application
    Filed: July 28, 2003
    Publication date: February 12, 2004
    Inventors: Etsuro Morita, Takaaki Shiota, Yoshihisa Nonogaki, Yoshinobu Nakada, Hisashi Furuya, Hiroshi Koya, Jun Furukawa, Hideo Tanaka, Yuji Nakata
  • Patent number: 6682597
    Abstract: A method of heat-treating a silicon wafer has the steps of: preparing a silicon wafer having an oxygen concentration of 1.2×1018 atoms/cm3 or less (old ASTM) without generating crystal originated particles(COP'S) and interstitial-type large dislocation(L/D); forming a polysilicon layer of 0.1 &mgr;m to 1.6 &mgr;m in thickness on a back of the silicon wafer by a chemical-vapor deposition at a temperature of 670° C.±30° C.; and heat-treating the silicon wafer having the polysilicon layer in an oxygen atmosphere at 1000° C.±30° C. for 2 to 5 hours and subsequently at 1130° C.±30° C. for 1 to 16 hours. In this method, the silicon wafer before the formation of the polysilicon layer thereon is the type of a wafer in which oxidation induced stacking faults(OSF's) manifest itself at a center of the wafer when the wafer is subjected to the heat-treatment.
    Type: Grant
    Filed: June 3, 2002
    Date of Patent: January 27, 2004
    Assignee: Mitsubishi Materials Silicon Corporation
    Inventors: Hiroshi Koya, Hisashi Furuya, Yoji Suzuki, Yukio Muroi, Takaaki Shiota
  • Patent number: 6663708
    Abstract: An ingot is manufactured by pulling it up such that V/Ga and V/Gb become 0.23 to 0.50 mm2/minute ° C., respectively, where V (mm/minute) is a pulling-up speed, and Ga (° C./mm) is and axial temperature gradient at the center of the ingot and Gb (° C./mm) is an axial temperature gradient at the edge of the ingot at temperatures in a range of 1,300° C. to a melting pointy of silicon. A wafer obtained by slicing the ingot is heat treated in a reductive atmosphere at temperature in a renge of 1,050° C. to 1,220° C. for 30 to 150 minutes. A silicon wafer free of OSF's, free of COP's, and substantially free of contamination such as Fe and of occurence of slip, is obtained.
    Type: Grant
    Filed: September 22, 2000
    Date of Patent: December 16, 2003
    Assignee: Mitsubishi Materials Silicon Corporation
    Inventors: Etsuro Morita, Takaaki Shiota, Yoshihisa Nonogaki, Yoshinobu Nakada, Hisashi Furuya, Hiroshi Koya, Jun Furukawa, Hideo Tanaka, Yuji Nakata
  • Publication number: 20030051660
    Abstract: A method of heat-treating a silicon wafer has the steps of: preparing a silicon wafer having an oxygen concentration of 1.2×1018 atoms/cm3 or less (old ASTM) without generating crystal originated particles(COP'S) and interstitial-type large dislocation(L/D); forming a polysilicon layer of 0.1 &mgr;m to 1.6 &mgr;m in thickness on a back of the silicon wafer by a chemical-vapor deposition at a temperature of 670° C.±30° C.; and heat-treating the silicon wafer having the polysilicon layer in an oxygen atmosphere at 1000° C.±30° C. for 2 to 5 hours and subsequently at 1130° C.±30° C. for 1 to 16 hours. In this method, the silicon wafer before the formation of the polysilicon layer thereon is the type of a wafer in which oxidation induced stacking faults(OSF's) manifest itself at a center of the wafer when the wafer is subjected to the heat-treatment.
    Type: Application
    Filed: June 3, 2002
    Publication date: March 20, 2003
    Inventors: Hiroshi Koya, Hisashi Furuya, Yoji Suzuki, Yukio Muroi, Takaaki Shiota
  • Patent number: 6461447
    Abstract: A substrate having a surface on which silicon is epitaxially grown; wherein the substrate is cut from an oxygen induced stacking fault generation area of a single crystal silicon rod grown by the Czochralski method.
    Type: Grant
    Filed: June 30, 2000
    Date of Patent: October 8, 2002
    Assignee: Mitsubish Denki Kabushiki Kaisha
    Inventors: Hiroshi Shinyashiki, Hiroshi Koya, Tomonori Yamaoka, Kazuhito Matsukawa, Yasuhiro Kimura, Hidekazu Yamamoto
  • Patent number: 6428619
    Abstract: A method of heat-treating a silicon wafer has the steps of: preparing a silicon wafer having an oxygen concentration of 1.2×1018 atoms/cm3 or less (old ASTM) without generating crystal originated particles(COP'S) and interstitial-type large dislocation(L/D); forming a polysilicon layer of 0.1 &mgr;m to 1.6 &mgr;m in thickness on a back of the silicon wafer by a chemical-vapor deposition at a temperature of 670° C.±30° C.; and heat-treating the silicon wafer having the polysilicon layer in an oxygen atmosphere at 1000° C.±30° C. for 2 to 5 hours and subsequently at 1130° C.±30° C. for 1 to 16 hours. In this method, the silicon wafer before the formation of the polysilicon layer thereon is the type of a wafer in which oxidation induced stacking faults(OSF's) manifest itself at a center of the wafer when the wafer is subjected to the heat-treatment.
    Type: Grant
    Filed: October 23, 2000
    Date of Patent: August 6, 2002
    Assignee: Mitsubishi Materials Silicon Corporation
    Inventors: Hiroshi Koya, Hisashi Furuya, Yoji Suzuki, Yukio Muroi, Takaaki Shiota