Patents by Inventor Tsutomu Kiyosawa

Tsutomu Kiyosawa 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: 11171214
    Abstract: Variations in device characteristics in a plane parallel to the principal surface of a semiconductor wafer are suppressed. A semiconductor epitaxial wafer includes a semiconductor wafer and a first conductivity type semiconductor epitaxial layer that is disposed on a principal surface of the semiconductor wafer and contains a first conductivity type impurity, and the thickness distribution of the semiconductor epitaxial layer and the concentration distribution of the impurity in the semiconductor epitaxial layer have a positive correlation in a plane parallel to the principal surface of the semiconductor wafer.
    Type: Grant
    Filed: January 29, 2020
    Date of Patent: November 9, 2021
    Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.
    Inventors: Tsutomu Kiyosawa, Atsushi Ohoka
  • Publication number: 20200303506
    Abstract: Variations in device characteristics in a plane parallel to the principal surface of a semiconductor wafer are suppressed. A semiconductor epitaxial wafer includes a semiconductor wafer and a first conductivity type semiconductor epitaxial layer that is disposed on a principal surface of the semiconductor wafer and contains a first conductivity type impurity, and the thickness distribution of the semiconductor epitaxial layer and the concentration distribution of the impurity in the semiconductor epitaxial layer have a positive correlation in a plane parallel to the principal surface of the semiconductor wafer.
    Type: Application
    Filed: January 29, 2020
    Publication date: September 24, 2020
    Inventors: TSUTOMU KIYOSAWA, ATSUSHI OHOKA
  • Patent number: 10763330
    Abstract: A silicon carbide semiconductor element includes a silicon carbide semiconductor layer of a first conductivity type, a body region of a second conductivity type, a channel layer made of a silicon carbide semiconductor disposed on the silicon carbide semiconductor layer so as to be in contact with at least a part of the body region, and a gate electrode disposed on the channel layer via a gate insulating film. The channel layer has a multilayer structure of a high-concentration impurity layer containing impurities of the first conductivity type, a first medium-concentration impurity layer containing impurities of the first conductivity type, and a first low-concentration impurity layer containing impurities of the first conductivity type. The first low-concentration impurity layer is disposed closer to the body region than the high-concentration impurity layer and the first medium-concentration impurity layer.
    Type: Grant
    Filed: January 23, 2019
    Date of Patent: September 1, 2020
    Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.
    Inventor: Tsutomu Kiyosawa
  • Patent number: 10600880
    Abstract: A semiconductor device includes a substrate having a main surface inclined in an off-direction from a {0001} surface, and a semiconductor layer. The semiconductor layer includes a level difference for alignment mark. An epitaxial layer is disposed on a first portion of the main surface, the first portion being situated on an off-angle upstream side of the level difference, and on a second portion of the main surface, the second portion being situated on an off-angle downstream side of the level difference. A value of |WL?WR| is 1 ?m or less, in which WL represents a distance from a center of the level difference to a boundary between an off-angle upstream side corner portion of the level difference and a main surface or a {0001} facet plane generated on the main surface, and WR represents a distance from the center of the level difference to a boundary between an off-angle downstream side corner portion of the level difference and the main surface or the {0001} facet plane generated on the main surface.
    Type: Grant
    Filed: July 5, 2018
    Date of Patent: March 24, 2020
    Assignee: Panasonic Intellectual Property Management Co., Ltd.
    Inventors: Tsutomu Kiyosawa, Yasuyuki Yanase, Kazuhiro Kagawa
  • Patent number: 10573739
    Abstract: A method of producing a semiconductor device including steps (A) and (B). Step (A) is preparing a semiconductor epitaxial wafer including a plurality of device regions, each including a body region contacting a semiconductor layer. Step (B) is forming a channel layer contacting at least a part of the body region by epitaxial growth of a semiconductor on a surface of the semiconductor layer. The channel layer contains an impurity at a concentration ranging from 1×1018 cm?3 to 1×1019 cm?3, inclusive, and has a thickness ranging from 10 nm to 100 nm, inclusive. In the step (B), a condition for the epitaxial growth is controlled so that, in a plane parallel to the main surface of the semiconductor wafer, a thickness distribution in the channel layer and a concentration distribution of the impurity in the channel layer are negatively correlated to each other.
    Type: Grant
    Filed: November 8, 2018
    Date of Patent: February 25, 2020
    Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.
    Inventor: Tsutomu Kiyosawa
  • Patent number: 10573740
    Abstract: A method of producing a semiconductor device includes the following steps (A), (B), and (C). In the step (A), a semiconductor epitaxial wafer is prepared. The semiconductor epitaxial wafer includes a body region. In the step (B), a channel layer is formed by epitaxial growth. In the step (C), a gate insulation film is formed on the channel layer. The channel layer contains impurity at a concentration ranging from 1×1018 cm?3 to 1×1019 cm?3, inclusive, and has a thickness ranging from 10 nm to 100 nm, inclusive. In the steps of (B) and (C), a condition for the epitaxial growth and a condition for forming the gate insulation film are controlled so that a thickness distribution in the channel layer and a thickness distribution in the gate insulation film are positively correlated to each other.
    Type: Grant
    Filed: June 28, 2019
    Date of Patent: February 25, 2020
    Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.
    Inventor: Tsutomu Kiyosawa
  • Publication number: 20190326428
    Abstract: A method of producing a semiconductor device includes the following steps (A), (B), and (C). In the step (A), a semiconductor epitaxial wafer is prepared. The semiconductor epitaxial wafer includes a body region. In the step (B), a channel layer is formed by epitaxial growth. In the step (C), a gate insulation film is formed on the channel layer. The channel layer contains impurity at a concentration ranging from 1×1018 cm?3 to 1×1019 cm?3, inclusive, and has a thickness ranging from 10 nm to 100 nm, inclusive. In the steps of (B) and (C), a condition for the epitaxial growth and a condition for forming the gate insulation film are controlled so that a thickness distribution in the channel layer and a thickness distribution in the gate insulation film are positively correlated to each other.
    Type: Application
    Filed: June 28, 2019
    Publication date: October 24, 2019
    Inventor: Tsutomu KIYOSAWA
  • Publication number: 20190245039
    Abstract: A silicon carbide semiconductor element includes a silicon carbide semiconductor layer of a first conductivity type, a body region of a second conductivity type, a channel layer made of a silicon carbide semiconductor disposed on the silicon carbide semiconductor layer so as to be in contact with at least a part of the body region, and a gate electrode disposed on the channel layer via a gate insulating film. The channel layer has a multilayer structure of a high-concentration impurity layer containing impurities of the first conductivity type, a first medium-concentration impurity layer containing impurities of the first conductivity type, and a first low-concentration impurity layer containing impurities of the first conductivity type. The first low-concentration impurity layer is disposed closer to the body region than the high-concentration impurity layer and the first medium-concentration impurity layer.
    Type: Application
    Filed: January 23, 2019
    Publication date: August 8, 2019
    Inventor: TSUTOMU KIYOSAWA
  • Patent number: 10361297
    Abstract: A semiconductor epitaxial wafer includes a semiconductor wafer, and a semiconductor layer of a first conductivity type disposed on a main surface of the semiconductor wafer. The semiconductor epitaxial wafer includes a plurality of device regions. The plurality of device regions each include a body region of a second conductivity type in contact with the semiconductor layer, a source region of the first conductivity type in contact with the body region, and a channel layer that is constituted by a semiconductor, and that is disposed on the semiconductor layer so as to be in contact with at least a part of the body region. In a plane parallel to the main surface of the semiconductor wafer, a thickness distribution in the channel layer and a concentration distribution of the first conductivity type impurity in the channel layer are negatively correlated to each other.
    Type: Grant
    Filed: February 14, 2018
    Date of Patent: July 23, 2019
    Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.
    Inventor: Tsutomu Kiyosawa
  • Patent number: 10355091
    Abstract: Semiconductor device includes semiconductor substrate, drift layer, first electrode, and second electrode. Semiconductor substrate is of a first conductivity type and is formed of a silicon carbide semiconductor, a gallium nitride semiconductor, or the like. For example, semiconductor substrate is an n-type silicon carbide semiconductor substrate. Drift layer is an epitaxial semiconductor layer of the first conductivity type which is formed on upper surface of semiconductor substrate by epitaxial growth. Drift layer is formed of, for example, an n-type silicon carbide semiconductor. Drift layer has a thickness of t. For example, the thickness t is between about 5 ?m and about 100 ?m (inclusive).
    Type: Grant
    Filed: December 14, 2018
    Date of Patent: July 16, 2019
    Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.
    Inventors: Tsutomu Kiyosawa, Atsushi Ohoka
  • Publication number: 20190123147
    Abstract: Semiconductor device includes semiconductor substrate, drift layer, first electrode, and second electrode. Semiconductor substrate is of a first conductivity type and is formed of a silicon carbide semiconductor, a gallium nitride semiconductor, or the like. For example, semiconductor substrate is an n-type silicon carbide semiconductor substrate. Drift layer is an epitaxial semiconductor layer of the first conductivity type which is formed on upper surface of semiconductor substrate by epitaxial growth. Drift layer is formed of, for example, an n-type silicon carbide semiconductor. Drift layer has a thickness of t. For example, the thickness t is between about 5 ?m and about 100 ?m (inclusive).
    Type: Application
    Filed: December 14, 2018
    Publication date: April 25, 2019
    Inventors: Tsutomu KIYOSAWA, Atsushi OHOKA
  • Patent number: 10262909
    Abstract: Semiconductor layer is formed on semiconductor substrate. Semiconductor layer has a plurality of well regions in a surface remote from semiconductor substrate. Semiconductor layer includes drift region in addition to the plurality of well regions. The plurality of well regions each include body region, source region, and contact region. Source region is in contact with body region. Contact region is in contact with both body region and source region. Body region, source region, and source wire are at an identical potential because of contact region. Semiconductor layer includes ineffective region R at the surface remote from semiconductor substrate.
    Type: Grant
    Filed: October 24, 2018
    Date of Patent: April 16, 2019
    Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.
    Inventor: Tsutomu Kiyosawa
  • Publication number: 20190097037
    Abstract: A method of producing a semiconductor device including steps (A) and (B). Step (A) is preparing a semiconductor epitaxial wafer including a plurality of device regions, each including a body region contacting a semiconductor layer. Step (B) is forming a channel layer contacting at least a part of the body region by epitaxial growth of a semiconductor on a surface of the semiconductor layer. The channel layer contains an impurity at a concentration ranging from 1×1018 cm?3 to 1×1019 cm?3, inclusive, and has a thickness ranging from 10 nm to 100 nm, inclusive. In the step (B), a condition for the epitaxial growth is controlled so that, in a plane parallel to the main surface of the semiconductor wafer, a thickness distribution in the channel layer and a concentration distribution of the impurity in the channel layer are negatively correlated to each other.
    Type: Application
    Filed: November 8, 2018
    Publication date: March 28, 2019
    Inventor: Tsutomu KIYOSAWA
  • Publication number: 20190067133
    Abstract: Semiconductor layer is formed on semiconductor substrate. Semiconductor layer has a plurality of well regions in a surface remote from semiconductor substrate. Semiconductor layer includes drift region in addition to the plurality of well regions. The plurality of well regions each include body region, source region, and contact region. Source region is in contact with body region. Contact region is in contact with both body region and source region. Body region, source region, and source wire are at an identical potential because of contact region. Semiconductor layer includes ineffective region R at the surface remote from semiconductor substrate.
    Type: Application
    Filed: October 24, 2018
    Publication date: February 28, 2019
    Inventor: Tsutomu KIYOSAWA
  • Patent number: 10211293
    Abstract: Semiconductor device 101 includes semiconductor substrate 10, drift layer 20, first electrode 50, and second electrode 60. Semiconductor substrate 10 is of a first conductivity type and is formed of a silicon carbide semiconductor, a gallium nitride semiconductor, or the like. For example, semiconductor substrate 10 is an n-type silicon carbide semiconductor substrate. Drift layer 20 is an epitaxial semiconductor layer of the first conductivity type which is formed on upper surface 10a of semiconductor substrate 10 by epitaxial growth. Drift layer 20 is formed of for example, an n-type silicon carbide semiconductor. Drift layer 20 has a thickness of t. For example, the thickness t is between about 5 ?m and about 100 ?m (inclusive).
    Type: Grant
    Filed: March 5, 2018
    Date of Patent: February 19, 2019
    Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.
    Inventors: Tsutomu Kiyosawa, Atsushi Ohoka
  • Patent number: 10141235
    Abstract: Semiconductor layer 110 is formed on semiconductor substrate 101. Semiconductor layer 110 has a plurality of well regions 103 in a surface remote from semiconductor substrate 101. Semiconductor layer 110 includes drift region 102 in addition to the plurality of well regions 103. The plurality of well regions 103 each include body region 105, source region 108, and contact region 109. Source region 108 is in contact with body region 105. Contact region 109 is in contact with both body region 105 and source region 108. Body region 105, source region 108, and source wire 118 are at an identical potential because of contact region 109. Semiconductor layer 110 includes ineffective region R at the surface remote from semiconductor substrate 101.
    Type: Grant
    Filed: March 5, 2018
    Date of Patent: November 27, 2018
    Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.
    Inventor: Tsutomu Kiyosawa
  • Publication number: 20180315823
    Abstract: A semiconductor device includes a substrate having a main surface inclined in an off-direction from a {0001} surface, and a semiconductor layer. The semiconductor layer includes a level difference for alignment mark. An epitaxial layer is disposed on a first portion of the main surface, the first portion being situated on an off-angle upstream side of the level difference, and on a second portion of the main surface, the second portion being situated on an off-angle downstream side of the level difference. A value of |WL?WR| is 1 ?m or less, in which WL represents a distance from a center of the level difference to a boundary between an off-angle upstream side corner portion of the level difference and a main surface or a {0001} facet plane generated on the main surface, and WR represents a distance from the center of the level difference to a boundary between an off-angle downstream side corner portion of the level difference and the main surface or the {0001} facet plane generated on the main surface.
    Type: Application
    Filed: July 5, 2018
    Publication date: November 1, 2018
    Inventors: Tsutomu KIYOSAWA, Yasuyuki YANASE, Kazuhiro KAGAWA
  • Publication number: 20180277453
    Abstract: Semiconductor layer 110 is formed on semiconductor substrate 101. Semiconductor layer 110 has a plurality of well regions 103 in a surface remote from semiconductor substrate 101. Semiconductor layer 110 includes drift region 102 in addition to the plurality of well regions 103. The plurality of well regions 103 each include body region 105, source region 108, and contact region 109. Source region 108 is in contact with body region 105. Contact region 109 is in contact with both body region 105 and source region 108. Body region 105, source region 108, and source wire 118 are at an identical potential because of contact region 109. Semiconductor layer 110 includes ineffective region R at the surface remote from semiconductor substrate 101.
    Type: Application
    Filed: March 5, 2018
    Publication date: September 27, 2018
    Inventor: TSUTOMU KIYOSAWA
  • Publication number: 20180277636
    Abstract: Semiconductor device 101 includes semiconductor substrate 10, drift layer 20, first electrode 50, and second electrode 60. Semiconductor substrate 10 is of a first conductivity type and is formed of a silicon carbide semiconductor, a gallium nitride semiconductor, or the like. For example, semiconductor substrate 10 is an n-type silicon carbide semiconductor substrate. Drift layer 20 is an epitaxial semiconductor layer of the first conductivity type which is formed on upper surface 10a of semiconductor substrate 10 by epitaxial growth. Drift layer 20 is formed of for example, an n-type silicon carbide semiconductor. Drift layer 20 has a thickness of t. For example, the thickness t is between about 5 ?m and about 100 ?m (inclusive).
    Type: Application
    Filed: March 5, 2018
    Publication date: September 27, 2018
    Inventors: TSUTOMU KIYOSAWA, ATSUSHI OHOKA
  • Publication number: 20180254339
    Abstract: A semiconductor epitaxial wafer includes a semiconductor wafer, and a semiconductor layer of a first conductivity type disposed on a main surface of the semiconductor wafer. The semiconductor epitaxial wafer includes a plurality of device regions. The plurality of device regions each include a body region of a second conductivity type in contact with the semiconductor layer, a source region of the first conductivity type in contact with the body region, and a channel layer that is constituted by a semiconductor, and that is disposed on the semiconductor layer so as to be in contact with at least a part of the body region. In a plane parallel to the main surface of the semiconductor wafer, a thickness distribution in the channel layer and a concentration distribution of the first conductivity type impurity in the channel layer are negatively correlated to each other.
    Type: Application
    Filed: February 14, 2018
    Publication date: September 6, 2018
    Inventor: TSUTOMU KIYOSAWA