Patents by Inventor Yuhji Ishiwari

Yuhji Ishiwari 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).

  • Method for producing silicon ingot having directional solidification structure and apparatus for producing the same
    Patent number: 6378835
    Abstract: A method for producing a silicon ingot having a directional solidification structure comprising the steps of: placing a silicon raw material into a crucible of a melting device constructed by mounting a chill plate on an underfloor heater, mounting a crucible with a large cross-sectional area on the chill plate, providing an overhead heater over the crucible, and surrounding the circumference of the crucible with a heat insulator; heat-melting the silicon raw material by flowing an electric current through the underfloor heater and overhead heater; chilling the bottom of the crucible by halting the electric current through the underfloor heater after the silicon raw material has been completely melted to form a molten silicon; chilling the bottom of the crucible by flowing an inert gas through the chill plate; and intermittently or continuously lowering the temperature of the overhead heater by intermittently or continuously decreasing the electric current through the overhead heater, and an apparatus for pro
    Type: Grant
    Filed: February 25, 1999
    Date of Patent: April 30, 2002
    Assignee: Mitsubishi Materials Corporation
    Inventors: Saburo Wakita, Akira Mitsuhashi, Yoshinobu Nakada, Jun-ichi Sasaki, Yuhji Ishiwari
  • Method for producing silicon ingot having directional solidification structure and apparatus for producing the same
    Patent number: 6299682
    Abstract: A method for producing a silicon ingot having a directional solidification structure comprising the steps of: placing a silicon raw material into a crucible of a melting device constructed by mounting a chill plate on an underfloor heater, mounting a crucible with a large cross-sectional area on the chill plate, providing an overhead heater over the crucible, and surrounding the circumference of the crucible with a heat insulator; heat-melting the silicon raw material by flowing an electric current through the underfloor heater and overhead heater; chilling the bottom of the crucible by halting the electric current through the underfloor heater after the silicon raw material has been completely melted to form a molten silicon; chilling the bottom of the crucible by flowing an inert gas through the chill plate; and intermittently or continuously lowering the temperature of the overhead heater by intermittently or continuously decreasing the electric current through the overhead heater, and an apparatus for pro
    Type: Grant
    Filed: September 8, 2000
    Date of Patent: October 9, 2001
    Assignee: Mitsubishi Materials Corporation
    Inventors: Saburo Wakita, Akira Mitsuhashi, Yoshinobu Nakada, Jun-ichi Sasaki, Yuhji Ishiwari