Patents by Inventor Keiichiro HIRAKI

Keiichiro HIRAKI 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: 20230369416
    Abstract: To provide a silicon wafer with extremely low resistivity by containing an ultra-high concentration of boron, the silicon wafer having a high gettering ability by enabling formation of oxygen precipitates at a high concentration, and making it possible to suppress the occurrence of epitaxial defects originating from oxygen precipitates when an epitaxial layer is formed. Disclosed is a silicon wafer made of monocrystalline silicon, the silicon wafer containing boron as a dopant and having a resistivity of 1 m?·cm or more and 10 m?·cm or less, the silicon wafer having an oxygen concentration of 14.5×1017 atoms/cm3 or more and 16×1017 atoms/cm3 or less, and a carbon concentration of 2×1016 atoms/cm3 or more and 5×1017 atoms/cm3 or less, and the silicon wafer being free from COPs and dislocation clusters.
    Type: Application
    Filed: May 10, 2023
    Publication date: November 16, 2023
    Applicant: SUMCO Corporation
    Inventor: Keiichiro HIRAKI
  • Patent number: 10526728
    Abstract: A manufacturing method of this invention includes: a step of slicing a silicon single crystal containing boron as an acceptor and obtaining a non-heat-treated silicon wafer, a step of determining a boron concentration with respect to the non-heat-treated silicon wafer, and a step of determining an oxygen donor concentration with respect to the non-heat-treated silicon wafer, in which a determination as to whether or not to perform a heat treatment at a temperature of 300° C. or more on the non-heat-treated silicon wafer is made based on a boron concentration determined in the step of determining a boron concentration, and an oxygen donor concentration determined in the step of determining an oxygen donor concentration. By this means, a wafer in which unevenly distributed LPDs that are present on the wafer are reduced is obtained.
    Type: Grant
    Filed: April 10, 2015
    Date of Patent: January 7, 2020
    Assignee: SUMCO CORPORATION
    Inventors: Satoshi Kudo, Kouzou Nakamura, Toshiyuki Muranaka, Shuhei Matsuda, Tegi Kim, Keiichiro Hiraki
  • Publication number: 20170044688
    Abstract: A manufacturing method of this invention includes: a step of slicing a silicon single crystal containing boron as an acceptor and obtaining a non-heat-treated silicon wafer, a step of determining a boron concentration with respect to the non-heat-treated silicon wafer, and a step of determining an oxygen donor concentration with respect to the non-heat-treated silicon wafer, in which a determination as to whether or not to perform a heat treatment at a temperature of 300° C. or more on the non-heat-treated silicon wafer is made based on a boron concentration determined in the step of determining a boron concentration, and an oxygen donor concentration determined in the step of determining an oxygen donor concentration. By this means, a wafer in which unevenly distributed LPDs that are present on the wafer are reduced is obtained.
    Type: Application
    Filed: April 10, 2015
    Publication date: February 16, 2017
    Applicant: SUMCO CORPORATION
    Inventors: Satoshi KUDO, Kouzou NAKAMURA, Toshiyuki MURANAKA, Shuhei MATSUDA, Tegi KIM, Keiichiro HIRAKI
  • Patent number: 8771415
    Abstract: By determining a control direction of a pulling-up velocity without using a position or a width of an OSF region as an index, a subsequent pulling-up velocity profile is fed back and adjusted. A silicon single crystal ingot that does not include a COP and a dislocation cluster is grown by a CZ method, a silicon wafer is sliced from the silicon single crystal ingot, reactive ion etching is performed on the silicon wafer in an as-grown state, and a grown-in defect including silicon oxide is exposed as a protrusion on an etching surface. A growing condition in subsequent growing is fed back and adjusted on the basis of an exposed protrusion generation region. As a result, feedback with respect to a nearest batch can be performed without performing heat treatment to expose a defect.
    Type: Grant
    Filed: October 23, 2009
    Date of Patent: July 8, 2014
    Assignee: Sumco Corporation
    Inventors: Shigeru Umeno, Keiichiro Hiraki, Hiroaki Taguchi
  • Publication number: 20100111802
    Abstract: By determining a control direction of a pulling-up velocity without using a position or a width of an OSF region as an index, a subsequent pulling-up velocity profile is fed back and adjusted. A silicon single crystal ingot that does not include a COP and a dislocation cluster is grown by a CZ method, a silicon wafer is sliced from the silicon single crystal ingot, reactive ion etching is performed on the silicon wafer in an as-grown state, and a grown-in defect including silicon oxide is exposed as a protrusion on an etching surface. A growing condition in subsequent growing is fed back and adjusted on the basis of an exposed protrusion generation region. As a result, feedback with respect to a nearest batch can be performed without performing heat treatment to expose a defect.
    Type: Application
    Filed: October 23, 2009
    Publication date: May 6, 2010
    Applicant: SUMCO CORPORATION
    Inventors: Shigeru UMENO, Keiichiro HIRAKI, Hiroaki TAGUCHI