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).
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Patent number: 11171214Abstract: 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: GrantFiled: January 29, 2020Date of Patent: November 9, 2021Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.Inventors: Tsutomu Kiyosawa, Atsushi Ohoka
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Publication number: 20200303506Abstract: 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: ApplicationFiled: January 29, 2020Publication date: September 24, 2020Inventors: TSUTOMU KIYOSAWA, ATSUSHI OHOKA
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Patent number: 10763330Abstract: 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: GrantFiled: January 23, 2019Date of Patent: September 1, 2020Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.Inventor: Tsutomu Kiyosawa
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Patent number: 10600880Abstract: 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: GrantFiled: July 5, 2018Date of Patent: March 24, 2020Assignee: Panasonic Intellectual Property Management Co., Ltd.Inventors: Tsutomu Kiyosawa, Yasuyuki Yanase, Kazuhiro Kagawa
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Patent number: 10573739Abstract: 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: GrantFiled: November 8, 2018Date of Patent: February 25, 2020Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.Inventor: Tsutomu Kiyosawa
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Patent number: 10573740Abstract: 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: GrantFiled: June 28, 2019Date of Patent: February 25, 2020Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.Inventor: Tsutomu Kiyosawa
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Publication number: 20190326428Abstract: 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: ApplicationFiled: June 28, 2019Publication date: October 24, 2019Inventor: Tsutomu KIYOSAWA
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Publication number: 20190245039Abstract: 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: ApplicationFiled: January 23, 2019Publication date: August 8, 2019Inventor: TSUTOMU KIYOSAWA
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Patent number: 10361297Abstract: 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: GrantFiled: February 14, 2018Date of Patent: July 23, 2019Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.Inventor: Tsutomu Kiyosawa
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Patent number: 10355091Abstract: 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: GrantFiled: December 14, 2018Date of Patent: July 16, 2019Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.Inventors: Tsutomu Kiyosawa, Atsushi Ohoka
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Publication number: 20190123147Abstract: 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: ApplicationFiled: December 14, 2018Publication date: April 25, 2019Inventors: Tsutomu KIYOSAWA, Atsushi OHOKA
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Patent number: 10262909Abstract: 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: GrantFiled: October 24, 2018Date of Patent: April 16, 2019Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.Inventor: Tsutomu Kiyosawa
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Publication number: 20190097037Abstract: 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: ApplicationFiled: November 8, 2018Publication date: March 28, 2019Inventor: Tsutomu KIYOSAWA
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Publication number: 20190067133Abstract: 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: ApplicationFiled: October 24, 2018Publication date: February 28, 2019Inventor: Tsutomu KIYOSAWA
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Patent number: 10211293Abstract: 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: GrantFiled: March 5, 2018Date of Patent: February 19, 2019Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.Inventors: Tsutomu Kiyosawa, Atsushi Ohoka
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Patent number: 10141235Abstract: 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: GrantFiled: March 5, 2018Date of Patent: November 27, 2018Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.Inventor: Tsutomu Kiyosawa
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Publication number: 20180315823Abstract: 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: ApplicationFiled: July 5, 2018Publication date: November 1, 2018Inventors: Tsutomu KIYOSAWA, Yasuyuki YANASE, Kazuhiro KAGAWA
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Publication number: 20180277453Abstract: 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: ApplicationFiled: March 5, 2018Publication date: September 27, 2018Inventor: TSUTOMU KIYOSAWA
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Publication number: 20180277636Abstract: 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: ApplicationFiled: March 5, 2018Publication date: September 27, 2018Inventors: TSUTOMU KIYOSAWA, ATSUSHI OHOKA
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Publication number: 20180254339Abstract: 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: ApplicationFiled: February 14, 2018Publication date: September 6, 2018Inventor: TSUTOMU KIYOSAWA