Patents by Inventor Keiko MASUMOTO

Keiko MASUMOTO 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: 10879359
    Abstract: A silicon carbide epitaxial wafer (10) of the present invention is a silicon carbide epitaxial wafer including: a silicon carbide substrate (1) and a silicon carbide layer (2) provided on a first principal plane (1A) of the silicon carbide substrate (1) and having a film thickness of 100 ?m or more, wherein a warpage amount of the silicon carbide epitaxial wafer is ?20 ?m or more and 20 ?m or less.
    Type: Grant
    Filed: February 20, 2019
    Date of Patent: December 29, 2020
    Inventors: Keiko Masumoto, Satoshi Segawa, Kazutoshi Kojima, Tomohisa Kato, Toshiyuki Ohno
  • Publication number: 20190333998
    Abstract: A high quality silicon carbide epitaxial wafer using a p-type silicon carbide single crystal substrate of low resistivity. The silicon carbide epitaxial wafer includes a p-type 4H—SiC single crystal substrate that has a first main surface having an off angle with respect to (0001) plane, and has a resistivity of less than 0.4 ?cm, and a silicon carbide epitaxial layer that is disposed on the first main surface of the p-type 4H—SiC single crystal substrate, in which an off direction of the off angle is the <01-10> direction.
    Type: Application
    Filed: December 19, 2018
    Publication date: October 31, 2019
    Inventors: Keiko MASUMOTO, Takashi MITANI, Kazuma ETO, Kazutoshi KOJIMA, Tomohisa KATO
  • Publication number: 20190273136
    Abstract: A silicon carbide epitaxial wafer (10) of the present invention is a silicon carbide epitaxial wafer including: a silicon carbide substrate (1) and a silicon carbide layer (2) provided on a first principal plane (1A) of the silicon carbide substrate (1) and having a film thickness of 100 ?m or more, wherein a warpage amount of the silicon carbide epitaxial wafer is ?20 ?m or more and 20 ?m or less.
    Type: Application
    Filed: February 20, 2019
    Publication date: September 5, 2019
    Inventors: Keiko MASUMOTO, Satoshi SEGAWA, Kazutoshi KOJIMA, Tomohisa KATO, Toshiyuki OHNO
  • Patent number: 10329689
    Abstract: A subject of present invention is to enable reducing, even in growth at a high C/Si ratio, contamination by different polytypes with respect to a silicon carbide epitaxial wafer having a low off-angle, and to provide the silicon carbide epitaxial wafer which enables forming a reliable high voltage silicon carbide semiconductor element. The silicon carbide epitaxial wafer of the present invention is a silicon carbide epitaxial wafer comprising an epitaxially grown layer disposed on a silicon carbide substrate having an ?-type crystal structure and an off-angle tilted at an angle of more than 0° and less than 4° from a (0001) Si plane or a (000-1) C plane, wherein a region of a step bunching including five to ten bunched steps of 1 nm in height occupies 90% or more of the surface of the silicon carbide substrate.
    Type: Grant
    Filed: October 18, 2016
    Date of Patent: June 25, 2019
    Assignee: NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY
    Inventor: Keiko Masumoto
  • Patent number: 9587326
    Abstract: To provide silicon carbide epitaxial wafer in which occurrence of giant step bunchings (GSBs) caused by basal plane dislocations (BPDs) that occur during hydrogen etching is suppressed on low off-angle silicon carbide substrate to decrease surface defect density of epitaxially grown layer to allow formation of silicon carbide semiconductor device having high reliability, method for manufacturing the wafer, and apparatus for manufacturing the wafer, and silicon carbide semiconductor device having the wafer. A silicon carbide epitaxial wafer of the present invention is such that epitaxially grown layer is disposed on silicon carbide substrate which has ?-type crystal structure and in which (0001) Si face is tilted at greater than 0° and less than 5°, wherein surface defect density of the epitaxially grown layer based on giant step bunching caused by basal plane dislocation on substrate surface of the silicon carbide substrate is ?20/cm2.
    Type: Grant
    Filed: February 20, 2014
    Date of Patent: March 7, 2017
    Assignee: National Institute of Advanced Industrial Science and Technology
    Inventors: Keiko Masumoto, Kazutoshi Kojima, Kentaro Tamura
  • Publication number: 20170037538
    Abstract: A subject of present invention is to enable reducing, even in growth at a high C/Si ratio, contamination by different polytypes with respect to a silicon carbide epitaxial wafer having a low off-angle, and to provide the silicon carbide epitaxial wafer which enables forming a reliable high voltage silicon carbide semiconductor element. The silicon carbide epitaxial wafer of the present invention is a silicon carbide epitaxial wafer comprising an epitaxially grown layer disposed on a silicon carbide substrate having an ?-type crystal structure and an off-angle tilted at an angle of more than 0° and less than 4° from a (0001) Si plane or a (000-1) C plane, wherein a region of a step bunching including five to ten bunched steps of 1 nm in height occupies 90% or more of the surface of the silicon carbide substrate.
    Type: Application
    Filed: October 18, 2016
    Publication date: February 9, 2017
    Inventor: Keiko Masumoto
  • Publication number: 20160168751
    Abstract: To provide silicon carbide epitaxial wafer in which occurrence of giant step bunchings (GSBs) caused by basal plane dislocations (BPDs) that occur during hydrogen etching is suppressed on low off-angle silicon carbide substrate to decrease surface defect density of epitaxially grown layer to allow formation of silicon carbide semiconductor device having high reliability, method for manufacturing the wafer, and apparatus for manufacturing the wafer, and silicon carbide semiconductor device having the wafer. A silicon carbide epitaxial wafer of the present invention is such that epitaxially grown layer is disposed on silicon carbide substrate which has ?-type crystal structure and in which (0001) Si face is tilted at greater than 0° and less than 5°, wherein surface defect density of the epitaxially grown layer based on giant step bunching caused by basal plane dislocation on substrate surface of the silicon carbide substrate is ?20/cm2.
    Type: Application
    Filed: February 20, 2014
    Publication date: June 16, 2016
    Inventors: Keiko MASUMOTO, Kazutoshi KOJIMA, Kentaro TAMURA