Patents by Inventor Kyoko Okita

Kyoko Okita 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: 11862684
    Abstract: A recycle wafer of silicon carbide has a silicon carbide substrate and a first silicon carbide layer. The silicon carbide substrate has a first main surface and a second main surface opposite to the first main surface. The first silicon carbide layer is in contact with the first main surface. The silicon carbide substrate includes a substrate region that is within 10 ?m from the first main surface toward the second main surface. In a direction perpendicular to the first main surface, a value obtained by subtracting a value that is three times a standard deviation of a nitrogen concentration in the substrate region from an average value of the nitrogen concentration in the substrate region is greater than a minimum value of a nitrogen concentration in the first silicon carbide layer.
    Type: Grant
    Filed: September 26, 2019
    Date of Patent: January 2, 2024
    Assignee: Sumitomo Electric Industries, Ltd.
    Inventors: Tsubasa Honke, Kyoko Okita
  • Publication number: 20230357957
    Abstract: A silicon carbide substrate has a first main surface and a second main surface opposite to the first main surface. The silicon carbide substrate includes screw dislocations and pits having a maximum diameter of 1 ?m or more and 10 ?m or less in a direction parallel to the first main surface. When the screw dislocations and the pits are observed in the first main surface, a percentage obtained by dividing a number of the pits by a number of the screw dislocations is 1% or less. A concentration of magnesium in the first main surface is less than 1×1011 atoms/cm2.
    Type: Application
    Filed: November 10, 2020
    Publication date: November 9, 2023
    Inventors: Kyoko OKITA, Tsubasa HONKE, Shunsaku UETA
  • Patent number: 11781246
    Abstract: In a case where a detector is positioned in a [11-20] direction, and where a first measurement region including a center of a main surface is irradiated with an X ray in a direction within ±15° relative to a [?1-120] direction, a ratio of a maximum intensity of a first intensity profile is more than or equal to 1500. In a case where the detector is positioned in a direction parallel to a [?1100] direction, and where the first measurement region is irradiated with an X ray in a direction within ±6° relative to a [1-100] direction, a ratio of a maximum intensity of a second intensity profile is more than or equal to 1500. An absolute value of a difference between maximum value and minimum value of energy at which the first intensity profile indicates a maximum value is less than or equal to 0.06 keV.
    Type: Grant
    Filed: November 23, 2022
    Date of Patent: October 10, 2023
    Assignee: Sumitomo Electric Industries, Ltd.
    Inventors: Kyoko Okita, Takashi Sakurada, Eiryo Takasuka, Shunsaku Ueta, Sho Sasaki, Naoki Kaji, Hidehiko Mishima, Hirokazu Eguchi
  • Publication number: 20230081506
    Abstract: In a case where a detector is positioned in a [11-20] direction, and where a first measurement region including a center of a main surface is irradiated with an X ray in a direction within ±15° relative to a [?1-120] direction, a ratio of a maximum intensity of a first intensity profile is more than or equal to 1500. In a case where the detector is positioned in a direction parallel to a [?1100] direction, and where the first measurement region is irradiated with an X ray in a direction within ±6° relative to a [1-100] direction, a ratio of a maximum intensity of a second intensity profile is more than or equal to 1500. An absolute value of a difference between maximum value and minimum value of energy at which the first intensity profile indicates a maximum value is less than or equal to 0.06 keV.
    Type: Application
    Filed: November 23, 2022
    Publication date: March 16, 2023
    Applicant: Sumitomo Electric Industries, Ltd.
    Inventors: Kyoko OKITA, Takashi SAKURADA, Eiryo TAKASUKA, Shunsaku UETA, Sho SASAKI, Naoki KAJI, Hidehiko MISHIMA, Hirokazu EGUCHI
  • Patent number: 11535953
    Abstract: In a case where a detector is positioned in a [11-20] direction, and where a first measurement region including a center of a main surface is irradiated with an X ray in a direction within ±15° relative to a [?1-120] direction, a ratio of a maximum intensity of a first intensity profile is more than or equal to 1500. In a case where the detector is positioned in a direction parallel to a [?1100] direction, and where the first measurement region is irradiated with an X ray in a direction within ±6° relative to a [1-100] direction, a ratio of a maximum intensity of a second intensity profile is more than or equal to 1500. An absolute value of a difference between maximum value and minimum value of energy at which the first intensity profile indicates a maximum value is less than or equal to 0.06 keV.
    Type: Grant
    Filed: January 30, 2017
    Date of Patent: December 27, 2022
    Assignee: Sumitomo Electric Industries, Ltd.
    Inventors: Kyoko Okita, Takashi Sakurada, Eiryo Takasuka, Shunsaku Ueta, Sho Sasaki, Naoki Kaji, Hidehiko Mishima, Hirokazu Eguchi
  • Publication number: 20220403550
    Abstract: A ratio obtained by dividing a number of pits by a number of screw dislocations is equal to or smaller than 1%. The first main surface has a surface roughness equal to or smaller than 0.15 nm. An absolute value of a difference between the first wave number and the second wave number is equal to or smaller than 0.2 cm?1, and an absolute value of a difference between the first full width at half maximum and the second full width at half maximum is equal to or smaller than 0.25 cm?1.
    Type: Application
    Filed: November 12, 2020
    Publication date: December 22, 2022
    Inventors: Kyoko OKITA, Tsubasa HONKE, Shunsaku UETA
  • Patent number: 11459670
    Abstract: A silicon carbide epitaxial wafer includes a single crystal silicon carbide substrate of 4H polytype having a major surface thereof inclined at an angle ? to a {0001} plane toward a <11-20> direction, and a silicon carbide epitaxial layer of a thickness t formed on the major surface, wherein a diameter of the single crystal silicon carbide substrate is greater than or equal to 150 mm, wherein the angle ? exceeds 0°, and is less than or equal to 6°, wherein one or more pairs of a screw dislocation pit and a diagonal line defect situated at a distance of t/tan? from the pit are present in a surface of the silicon carbide epitaxial layer, and wherein a density of the pairs of a pit and a diagonal line defect is less than or equal to 2 pairs/cm2.
    Type: Grant
    Filed: August 28, 2018
    Date of Patent: October 4, 2022
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Tsutomu Hori, Takaya Miyase, Tsubasa Honke, Hirofumi Yamamoto, Kyoko Okita
  • Publication number: 20220220638
    Abstract: A silicon carbide substrate in accordance with the present disclosure includes a main surface. The silicon carbide substrate has a maximum diameter of 150 mm or more. In the main surface, a total area of a region in which a concentration of each of sodium, aluminum, potassium, calcium, titanium, iron, copper, and zinc is less than 5×1010 atoms/cm2 is more than or equal to 95% of an area of the main surface.
    Type: Application
    Filed: April 1, 2020
    Publication date: July 14, 2022
    Inventors: Kyoko OKITA, Tsubasa HONKE
  • Publication number: 20220220637
    Abstract: A silicon carbide substrate has a first main surface, a second main surface, and a chamfered portion. The second main surface is opposite to the first main surface. The chamfered portion is contiguous to each of the first main surface and the second main surface. The silicon carbide substrate has a maximum diameter of 150 mm or more. A surface manganese concentration in the chamfered portion is 1×1011 atoms/cm2 or less.
    Type: Application
    Filed: March 19, 2020
    Publication date: July 14, 2022
    Inventors: Tsubasa HONKE, Kyoko OKITA
  • Patent number: 11342418
    Abstract: Prescribed mathematical expressions are satisfied, where ?0 represents a wave number indicating a peak corresponding to a folded mode of a longitudinal optical branch of a Raman spectrum of silicon carbide having a polytype of 4H and having zero stress, ?max represents a maximum value of a wave number indicating a peak corresponding to a folded mode of a longitudinal optical branch of a Raman spectrum of a silicon carbide substrate in a region from a first main surface to a second main surface, ?max represents a minimum value of the wave number indicating the peak corresponding to the folded mode of the longitudinal optical branch of the Raman spectrum, and ?1 represents a wave number indicating a peak corresponding to a folded mode of a longitudinal optical branch of a Raman spectrum of the silicon carbide substrate at the first main surface.
    Type: Grant
    Filed: September 28, 2018
    Date of Patent: May 24, 2022
    Assignee: Sumitomo Electric Industries, Ltd.
    Inventors: Kyoko Okita, Tsubasa Honke
  • Patent number: 11322349
    Abstract: A TTV of the silicon carbide substrate is less than or equal to 3 ?m. The first main surface includes a first central region surrounded by a square having each side of 90 mm. An intersection of diagonal lines of the first central region coincides with a center of the first main surface. The first central region is constituted of nine square regions each having each side of 30 mm. A maximum LTV among the nine square regions is less than or equal to 1 ?m. An arithmetic mean roughness Sa in a second central region is less than or equal to 0.1 nm, the second central region being surrounded by a square centering on the intersection and having each side of 250 ?m.
    Type: Grant
    Filed: April 3, 2018
    Date of Patent: May 3, 2022
    Assignee: Sumitomo Electric Industries, Ltd.
    Inventors: Tsubasa Honke, Kyoko Okita
  • Publication number: 20220085172
    Abstract: A recycle wafer of silicon carbide has a silicon carbide substrate and a first silicon carbide layer. The silicon carbide substrate has a first main surface and a second main surface opposite to the first main surface. The first silicon carbide layer is in contact with the first main surface. The silicon carbide substrate includes a substrate region that is within 10 ?m from the first main surface toward the second main surface. In a direction perpendicular to the first main surface, a value obtained by subtracting a value that is three times a standard deviation of a nitrogen concentration in the substrate region from an average value of the nitrogen concentration in the substrate region is greater than a minimum value of a nitrogen concentration in the first silicon carbide layer.
    Type: Application
    Filed: September 26, 2019
    Publication date: March 17, 2022
    Inventors: Tsubasa HONKE, Kyoko OKITA
  • Patent number: 11034058
    Abstract: A silicon carbide ingot is cut using a wire. The silicon carbide ingot has a polytype of 4H—SiC. The silicon carbide ingot includes a top surface, a bottom surface opposite to the top surface, and a side surface between the top surface and the bottom surface. A direction from the bottom surface toward the top surface is a direction parallel to a [0001] direction or a direction inclined by less than or equal to 8° relative to the [0001] direction. In the cutting of the silicon carbide ingot, the silicon carbide ingot is cut from the side surface at a (000-1) plane side along a straight line parallel to a direction within ±5° relative to a direction that bisects an angle formed by a [1-100] direction and a [11-20] direction when viewed in the direction from the bottom surface toward the top surface.
    Type: Grant
    Filed: January 26, 2017
    Date of Patent: June 15, 2021
    Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Naoki Matsumoto, Kyoko Okita
  • Publication number: 20210060818
    Abstract: A silicon carbide ingot is cut using a wire. The silicon carbide ingot has a polytype of 4H—SiC. The silicon carbide ingot includes a top surface, a bottom surface opposite to the top surface, and a side surface between the.top surface and the bottom surface. A direction from the bottom surface toward the top surface is a direction parallel to a [0001] direction or a direction inclined by less than or equal to 8° relative to the [0001] direction. In the cutting of the silicon carbide ingot, the silicon carbide ingot is cut from the side surface at a (000-1) plane side along a straight line parallel to a direction within ±5° relative to a direction that bisects an angle formed by a [1-100] direction and a [11-20] direction when viewed in the direction from the bottom surface toward the top surface.
    Type: Application
    Filed: January 26, 2017
    Publication date: March 4, 2021
    Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Naoki MATSUMOTO, Kyoko OKITA
  • Publication number: 20210054529
    Abstract: In a case where a detector is positioned in a [11-20] direction, and where a first measurement region including a center of a main surface is irradiated with an X ray in a direction within ±15° relative to a [?1-120] direction, a ratio of a maximum intensity of a first intensity profile is more than or equal to 1500. In a case where the detector is positioned in a direction parallel to a [?1100] direction, and where the first measurement region is irradiated with an X ray in a direction within ±6° relative to a [1-100] direction, a ratio of a maximum intensity of a second intensity profile is more than or equal to 1500. An absolute value of a difference between maximum value and minimum value of energy at which the first intensity profile indicates a maximum value is less than or equal to 0.06 keV.
    Type: Application
    Filed: January 30, 2017
    Publication date: February 25, 2021
    Applicant: Sumitomo Electric Industries, Ltd.
    Inventors: Kyoko OKITA, Takashi SAKURADA, Eiryo TAKASUKA, Shunsaku UETA, Sho SASAKI, Naoki KAJI, Hidehiko MISHIMA, Hirokazu EGUCHI
  • Patent number: 10872759
    Abstract: A silicon carbide single crystal substrate includes a first main surface, a second main surface, and a circumferential edge portion. The second main surface is opposite to the first main surface. The circumferential edge portion connects the first main surface and the second main surface. The circumferential edge portion has a linear orientation flat portion, a first arc portion having a first radius, and a second arc portion connecting the orientation flat portion and the first arc portion and having a second radius smaller than the first radius, when viewed along a direction perpendicular to the first main surface.
    Type: Grant
    Filed: June 24, 2015
    Date of Patent: December 22, 2020
    Assignee: Sumitomo Electric Industries, Ltd.
    Inventors: Kyoko Okita, Tsubasa Honke
  • Publication number: 20200385887
    Abstract: A silicon carbide substrate according to the present disclosure is a silicon carbide substrate that includes a first main surface and a second main surface opposite to the first main surface, and is made of silicon carbide having a polytype of 4H. The first main surface has a maximum diameter of more than or equal to 140 mm. The first main surface is a {0001} plane or a plane inclined at an off angle of more than 0° and less than or equal to 8° relative to the {0001} plane. Half-widths of a peak corresponding to a folded mode of a longitudinal optical branch of a Raman spectrum of the silicon carbide substrate within a plane of the first main surface have an average value of less than 2.5 cm?1, and a standard deviation of less than or equal to 0.06 cm?1.
    Type: Application
    Filed: October 29, 2018
    Publication date: December 10, 2020
    Applicant: Sumitomo Electric Industries, Ltd.
    Inventors: Kyoko OKITA, Tsubasa HONKE
  • Publication number: 20200388683
    Abstract: Prescribed mathematical expressions are satisfied, where ?0 represents a wave number indicating a peak corresponding to a folded mode of a longitudinal optical branch of a Raman spectrum of silicon carbide having a polytype of 4H and having zero stress, ?max represents a maximum value of a wave number indicating a peak corresponding to a folded mode of a longitudinal optical branch of a Raman spectrum of a silicon carbide substrate in a region from a first main surface to a second main surface, ?max represents a minimum value of the wave number indicating the peak corresponding to the folded mode of the longitudinal optical branch of the Raman spectrum, and ?1 represents a wave number indicating a peak corresponding to a folded mode of a longitudinal optical branch of a Raman spectrum of the silicon carbide substrate at the first main surface.
    Type: Application
    Filed: September 28, 2018
    Publication date: December 10, 2020
    Applicant: Sumitomo Electric Industries, Ltd.
    Inventors: Kyoko OKITA, Tsubasa HONKE
  • Publication number: 20200362470
    Abstract: A silicon carbide epitaxial wafer includes a single crystal silicon carbide substrate of 4H polytype having a major surface thereof inclined at an angle ? to a {0001} plane toward a <11-20> direction, and a silicon carbide epitaxial layer of a thickness t formed on the major surface, wherein a diameter of the single crystal silicon carbide substrate is greater than or equal to 150 mm, wherein the angle ? exceeds 0°, and is less than or equal to 6°, wherein one or more pairs of a screw dislocation pit and a diagonal line defect situated at a distance of t/tan? from the pit are present in a surface of the silicon carbide epitaxial layer, and wherein a density of the pairs of a pit and a diagonal line defect is less than or equal to 2 pairs/cm2.
    Type: Application
    Filed: August 28, 2018
    Publication date: November 19, 2020
    Inventors: Tsutomu HORI, Takaya MIYASE, Tsubasa HONKE, Hirofumi YAMAMOTO, Kyoko OKITA
  • Patent number: 10741683
    Abstract: A semiconductor device has a semiconductor layer and a substrate. The semiconductor layer constitutes at least a part of a current path, and is made of silicon carbide. The substrate has a first surface supporting the semiconductor layer, and a second surface opposite to the first surface. Further, the substrate is made of silicon carbide having a 4H type single-crystal structure. Further, the substrate has a physical property in which a ratio of a peak strength in a wavelength of around 500 nm to a peak strength in a wavelength of around 390 nm is 0.1 or smaller in photoluminescence measurement. In this way, the semiconductor device is obtained to have a low on-resistance.
    Type: Grant
    Filed: March 12, 2018
    Date of Patent: August 11, 2020
    Assignee: Sumitomo Electric Industries, Ltd.
    Inventors: Shin Harada, Makoto Sasaki, Taro Nishiguchi, Kyoko Okita, Keiji Wada, Tomihito Miyazaki