Patents by Inventor Yumiko Hirano

Yumiko Hirano 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: 7291220
    Abstract: A silicon wafer made by the Czochralski method, including a ring-shaped OSF region and having nitrogen concentration ranging from 2.9×1014 to 5.0×1015 atoms/cm3 and oxygen concentration of 1.27×1018 to 3.0×1018 atoms/cm3 is heat-treated in a reducing-gas or inert-gas atmosphere, by increasing the temperature at the rate of 0.5° C./min to 2.0° C./min until the wafer is heated to a heat-treatment temperature of 1000 to 1200° C.
    Type: Grant
    Filed: August 19, 2005
    Date of Patent: November 6, 2007
    Assignee: Covalent Materials Corporation
    Inventor: Yumiko Hirano
  • Publication number: 20070068447
    Abstract: In order to control a crystal defective area, to inhibit slip generation at the time of annealing treatment, and to manufacture a high quality silicon wafer of high strength with sufficient yields, a method of manufacturing a silicon wafer is provided in which a silicon single crystal is grown by way of Czochralski method under conditions where an oxygen concentration is 0.9×1018 atoms/cm3 or more and an oxidization induced stacking fault density is the maximum in an area within 20 mm of a wafer circumference, and an as-grown defect density of the wafer obtained by slicing the silicon single crystal is 1×107/cm3 or more over the whole region of the wafer.
    Type: Application
    Filed: September 26, 2006
    Publication date: March 29, 2007
    Inventors: Koji Izunome, Yumiko Hirano, Takashi Watanabe, Kazuhiko Kashima, Hiroyuki Saito, Takeshi Senda
  • Publication number: 20060060129
    Abstract: A silicon wafer made by the Czochralski method, including a ring-shaped OSF region and having nitrogen concentration ranging from 2.9×1014 to 5.0×1015 atoms/cm3 and oxygen concentration of 1.27×1018 to 3.0×1018 atoms/cm3 is heat-treated in a reducing-gas or inert-gas atmosphere, by increasing the temperature at the rate of 0.5° C./min to 2.0° C./min until the wafer is heated to a heat-treatment temperature of 1000 to 1200° C.
    Type: Application
    Filed: August 19, 2005
    Publication date: March 23, 2006
    Inventor: Yumiko Hirano
  • Patent number: 6517632
    Abstract: A method of fabricating a silicon single crystal ingot and a method of fabricating a silicon wafer using the ingot, characterized in that: the method is structured in such a manner that the silicon single crystal ingot is pulled up from the silicon fused liquid 7 in which nitrogen N and carbon C are doped in polycrystalline silicon, by using the Czochralski method, and its nitrogen density is 1×1013-5×1015 atoms/cm3, and the carbon density is 5×1015-3×1016 atoms/cm3.
    Type: Grant
    Filed: January 17, 2001
    Date of Patent: February 11, 2003
    Assignee: Toshiba Ceramics Co., Ltd.
    Inventors: Toshirou Minami, Yumiko Hirano, Kouki Ikeuchi, Takashi Miyahara, Takashi Ishikawa, Osamu Kubota, Akihiko Kobayashi
  • Publication number: 20010029883
    Abstract: A method of fabricating a silicon single crystal ingot and a method of fabricating a silicon wafer using the ingot, characterized in that: the method is structured in such a manner that the silicon single crystal ingot is pulled up from the silicon fused liquid 7 in which nitrogen N and carbon C are doped in polycrystalline silicon, by using the Czochralski method, and its nitrogen density is 1×1013-5×1015 atoms/cm3, and the carbon density is 5×1015-3×1016 atoms/cm3.
    Type: Application
    Filed: January 17, 2001
    Publication date: October 18, 2001
    Inventors: Toshirou Minami, Yumiko Hirano, Kouki Ikeuchi, Takashi Miyahara, Takashi Ishikawa, Osamu Kubota, Akihiko Kobayashi