Patents by Inventor Weldon J. Bell

Weldon J. Bell 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).

  • OISF control in czochralski-grown crystals
    Patent number: 5820672
    Abstract: A method for controlling oxygen-induced stacking faults (OISF) in a silicon crystal (12) grown according to the Czochralski silicon crystal growing technique includes the steps of forming a flared top portion (18) of the silicon crystal (12) to a predetermined diameter (20) and tapering (23) the silicon crystal (12) top portion (18) to produce a cylindrical portion (22) having a second predetermined diameter. The second predetermined diameter is smaller than the first predetermined diameter. Because of the inward taper (23) OISF concentrates in the flared top portion (18) of silicon crystal (12).
    Type: Grant
    Filed: May 9, 1994
    Date of Patent: October 13, 1998
    Assignee: Texas Instruments Incorporated
    Inventors: Weldon J. Bell, H. Michael Grimes
  • Oxygen precipitation control in Czochralski-grown silicon crystals
    Patent number: 5795382
    Abstract: A method for controlling oxygen precipitation (106) in a silicon crystal (12) grown according to the Czochralski silicon crystal growing technique which includes the steps of forming a cylindrical portion (22) of the silicon crystal (12) from a reservoir of molten silicon (24) according to the Czochralski silicon crystal growing technique. The method includes the steps of terminating the Czochralski silicon crystal growing technique by forming a first tapered portion (101) in silicon crystal (12) at a predetermined rate. A second tapered portion (102) includes a cascaded middle portion (108) that connects to the first tapered portion (101) and that concentrates oxygen precipitation (106) within cascaded middle portion (108) and away from the cylindrical portion (22) of silicon crystal (12). At least a third tapered portion (104) is formed for separating silicon crystal (12) from molten silicon (24).
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: August 18, 1998
    Assignee: Texas Instruments Incorporated
    Inventors: Weldon J. Bell, H. Michael Grimes
  • System for oxygen precipitation control in silicon crystals
    Patent number: 5607507
    Abstract: A method for controlling oxygen precipitation (106) in a silicon crystal (12) grown according to the Czochralski silicon crystal growing technique which includes the steps of forming a cylindrical portion (22) of the silicon crystal (12) from a reservoir of molten silicon (24) according to the Czochralski silicon crystal growing technique. The method includes the steps of terminating the Czochralski silicon crystal growing technique by forming a first tapered portion (101) in silicon crystal (12) at a predetermined rate. A second tapered portion (102) includes a cascaded middle portion (108) that connects to the first tapered portion (101) and that concentrates oxygen precipitation (106) within cascaded middle portion (108) and away from the cylindrical portion (22) of silicon crystal (12). At least a third tapered portion (104) is formed for separating silicon crystal (12) from molten silicon (24).
    Type: Grant
    Filed: August 21, 1995
    Date of Patent: March 4, 1997
    Assignee: Texas Instruments Incorporated
    Inventors: Weldon J. Bell, H. Michael Grimes
  • Oxygen precipitation control in czochralski-grown silicon cyrstals
    Patent number: 5474020
    Abstract: A method for controlling oxygen precipitation (106) in a silicon crystal (12) grown according to the Czochralski silicon crystal growing technique which includes the steps of forming a cylindrical portion (22) of the silicon crystal (12) from a reservoir of molten silicon (24) according to the Czochralski silicon crystal growing technique. The method includes the steps of terminating the Czochralski silicon crystal growing technique by forming a first tapered portion (101) in silicon crystal (12) at a predetermined rate. A second tapered portion (102) includes a cascaded middle portion (108) that connects to the first tapered portion (101) and that concentrates oxygen precipitation (106) within cascaded middle portion (108) and away from the cylindrical portion (22) of silicon crystal (12). At least a third tapered portion (104) is formed for separating silicon crystal (12) from molten silicon (24).
    Type: Grant
    Filed: May 6, 1994
    Date of Patent: December 12, 1995
    Assignee: Texas Instruments Incorporated
    Inventors: Weldon J. Bell, H. Michael Grimes