Patents by Inventor Kiichiro Kitaura

Kiichiro Kitaura 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: 5471949
    Abstract: A method of producing a silicon single crystal, in which a cylindrical partition is immersed in a molten pure silicon liquid or molten silicon liquid containing a Sb dopant within a crucible and the molten liquid inside the partition is pulled up from the crucible to produce the silicon single crystal, wherein an interval between a lower end of the partition and a crucible bottom is changed to control an oxygen concentration in the pulling-up silicon single crystal. The interval is reduced in the case where the oxygen concentration in the pulling-up silicon single crystal is to be increased while the interval is increased in the case where the oxygen concentration is to be reduced.
    Type: Grant
    Filed: October 28, 1994
    Date of Patent: December 5, 1995
    Assignee: Sumitomo Sitix Corporation
    Inventors: Kaoru Kuramochi, Makoto Ito, Kiichiro Kitaura
  • Patent number: 5392729
    Abstract: A method of producing a silicon single crystal, in which a cylindrical partition is immersed in a molten pure silicon liquid or molten silicon liquid containing a Sb dopant within a crucible and the molten liquid inside the partition is pulled up from the crucible to produce the silicon single crystal, wherein an interval between a lower end of the partition and a crucible bottom is changed to control an oxygen concentration in the pulling-up silicon single crystal. The interval is reduced in the case where the oxygen concentration in the pulling-up silicon single crystal is to be increased while the interval is increased in the case where the oxygen concentration is to be reduced.
    Type: Grant
    Filed: September 26, 1990
    Date of Patent: February 28, 1995
    Assignees: Osaka Titanium Co., Ltd., Kyushu Electronic Metal Co., Ltd.
    Inventors: Kaoru Kuramochi, Makoto Ito, Kiichiro Kitaura
  • Patent number: 5260037
    Abstract: An apparatus and a method for producing a silicon single crystal by Czochralski method, whereby the silicon single crystal is pulled up from a crucible while the crucible is heated by a side heater in the lateral periphery of the crucible and a bottom heater facing the bottom of the crucible. The outputs of the side heater and bottom heater are controlled independently each other so that an oxygen concentration in the pull-up direction of the pulled-up silicon single crystal is rendered uniform. In addition to the output control of the heaters, a magnetic field is applied to a molten liquid in the crucible, so that, a dopant concentration in a radial direction of the pulled-up silicon single crystal is rendered uniform.
    Type: Grant
    Filed: June 26, 1992
    Date of Patent: November 9, 1993
    Assignees: Osaka Titanium Co., Ltd., Kyushu Electronic Metal Co., Ltd.
    Inventors: Kiichiro Kitaura, Makoto Ito, Kaoru Kuramochi
  • Patent number: 5152867
    Abstract: An apparatus and a method for producing a silicon single crystal by the Czochralski method, whereby the silicon single crystal is pulled up from a crucible while the crucible is heated by a side heater in the lateral periphery of the crucible and a bottom heater facing the bottom of the crucible. The outputs of the side heater and bottom heater are controlled independently of each other so that an oxygen concentration in the pull-up direction of the pulled-up silicon single crystal is rendered uniform. In addition to the output control of the heaters, a magnetic field is applied to a molten liquid in the crucible, so that, a dopant concentration in a radial direction of the pulled-up silicon single crystal is rendered uniform.
    Type: Grant
    Filed: July 19, 1990
    Date of Patent: October 6, 1992
    Assignees: Osaka Titanium Co., Ltd., Kyushu Electronic Metal Co., Ltd.
    Inventors: Kiichiro Kitaura, Makoto Ito, Kaoru Kuramochi