Patents by Inventor Yutaka Mikawa
Yutaka Mikawa 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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Publication number: 20210090886Abstract: A conductive C-plane GaN substrate has a resistivity of 2×10?2 ?·cm or less or an n-type carrier concentration of 1×1018 cm?3 or more at room temperature. At least one virtual line segment with a length of 40 mm can be drawn at least on one main surface of the substrate. The line segment satisfies at least one of the following conditions (A1) and (B1): (A1) when an XRC of (004) reflection is measured at 1 mm intervals on the line segment, a maximum value of XRC-FWHMs across all measurement points is less than 30 arcsec; and (B1) when an XRC of the (004) reflection is measured at 1 mm intervals on the line segment, a difference between maximum and minimum values of XRC peak angles across all the measurement points is less than 0.2°.Type: ApplicationFiled: December 9, 2020Publication date: March 25, 2021Applicant: MITSUBISHI CHEMICAL CORPORATIONInventors: Yutaka Mikawa, Hideo Fujisawa, Tae Mochizuki, Hideo Namita, Shinichiro Kawabata
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Patent number: 10903072Abstract: A conductive C-plane GaN substrate has a resistivity of 2×10?2 ?·cm or less or an n-type carrier concentration of 1×1018 cm?3 or more at room temperature. At least one virtual line segment with a length of 40 mm can be drawn at least on one main surface of the substrate. The line segment satisfies at least one of the following conditions (A1) and (B1): (A1) when an XRC of (004) reflection is measured at 1 mm intervals on the line segment, a maximum value of XRC-FWHMs across all measurement points is less than 30 arcsec; and (B1) when an XRC of the (004) reflection is measured at 1 mm intervals on the line segment, a difference between maximum and minimum values of XRC peak angles across all the measurement points is less than 0.2°.Type: GrantFiled: July 15, 2020Date of Patent: January 26, 2021Assignee: MITSUBISHI CHEMICAL CORPORATIONInventors: Yutaka Mikawa, Hideo Fujisawa, Tae Mochizuki, Hideo Namita, Shinichiro Kawabata
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Publication number: 20200350163Abstract: A conductive C-plane GaN substrate has a resistivity of 2×10?2 ?·cm or less or an n-type carrier concentration of 1×1018 cm?3 or more at room temperature. At least one virtual line segment with a length of 40 mm can be drawn at least on one main surface of the substrate. The line segment satisfies at least one of the following conditions (A1) and (B1): (A1) when an XRC of (004) reflection is measured at 1 mm intervals on the line segment, a maximum value of XRC-FWHMs across all measurement points is less than 30 arcsec; and (B1) when an XRC of the (004) reflection is measured at 1 mm intervals on the line segment, a difference between maximum and minimum values of XRC peak angles across all the measurement points is less than 0.2°.Type: ApplicationFiled: July 15, 2020Publication date: November 5, 2020Applicant: MITSUBISHI CHEMICAL CORPORATIONInventors: Yutaka MIKAWA, Hideo FUJISAWA, Tae MOCHIZUKI, Hideo NAMITA, Shinichiro KAWABATA
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Publication number: 20200321438Abstract: A gallium nitride substrate comprising a first main surface and a second main surface opposite thereto, wherein the first main surface is a non-polar or semi-polar plane, a dislocation density measured by a room-temperature cathode luminescence method in the first main surface is 1×104 cm?2 or less, and an averaged dislocation density measured by a room-temperature cathode luminescence method in an optional square region sizing 250 ?m×250 ?m in the first main plan is 1×106 cm?2 or less.Type: ApplicationFiled: June 19, 2020Publication date: October 8, 2020Applicant: MITSUBISHI CHEMICAL CORPORATIONInventors: Yusuke Tsukada, Shuichi Kubo, Kazunori Kamada, Hideo Fujisawa, Tatsuhiro Ohata, Hirotaka Ikeda, Hajime Matsumoto, Yutaka Mikawa
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Patent number: 10796904Abstract: A conductive C-plane GaN substrate has a resistivity of 2×10?2 ?·cm or less or an n-type carrier concentration of 1×1018 cm?3 or more at room temperature. At least one virtual line segment with a length of 40 mm can be drawn at least on one main surface of the substrate. The line segment satisfies at least one of the following conditions (A1) and (B1): (A1) when an XRC of (004) reflection is measured at 1 mm intervals on the line segment, a maximum value of XRC-FWHMs across all measurement points is less than 30 arcsec; and (B1) when an XRC of the (004) reflection is measured at 1 mm intervals on the line segment, a difference between maximum and minimum values of XRC peak angles across all the measurement points is less than 0.2°.Type: GrantFiled: February 7, 2019Date of Patent: October 6, 2020Assignee: MITSUBISHI CHEMICAL CORPORATIONInventors: Yutaka Mikawa, Hideo Fujisawa, Tae Mochizuki, Hideo Namita, Shinichiro Kawabata
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Publication number: 20200303187Abstract: A method for growing a GaN crystal suitable as a material of GaN substrates including C-plane GaN substrates includes: a first step of preparing a GaN seed having a nitrogen polar surface; a second step of arranging a pattern mask on the nitrogen polar surface of the GaN seed, the pattern mask being provided with a periodical opening pattern comprising linear openings and including intersections, the pattern mask being arranged such that longitudinal directions of at least part of the linear openings are within ±3° from a direction of an intersection line between the nitrogen polar surface and an M-plane; and a third step of ammonothermally growing a GaN crystal through the pattern mask such that a gap is formed between the GaN crystal and the pattern mask.Type: ApplicationFiled: June 10, 2020Publication date: September 24, 2020Applicant: MITSUBISHI CHEMICAL CORPORATIONInventors: Yutaka MIKAWA, Hideo FUJISAWA, Tae MOCHIZUKI, Hideo NAMITA, Shinichiro KAWABATA
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Patent number: 10734485Abstract: The main purpose of the present invention is to provide: a nonpolar or semipolar GaN substrate, in which a nitride semiconductor crystal having a low stacking fault density can be epitaxially grown on the main surface of the substrate, and a technique required for the production of the substrate. This invention provides: a method for manufacturing an M-plane GaN substrate comprising; forming a mask pattern having a line-shaped opening parallel to an a-axis of a C-plane GaN substrate on an N-polar plane of the C-plane GaN substrate, growing a plane-shape GaN crystal of which thickness direction is an m-axis direction from the opening of the mask pattern by an ammonotharmal method, and cutting out the M-plane GaN substrate from the plane-shape GaN crystal.Type: GrantFiled: March 29, 2017Date of Patent: August 4, 2020Assignee: MITSUBISHI CHEMICAL CORPORATIONInventors: Yusuke Tsukada, Shuichi Kubo, Kazunori Kamada, Hideo Fujisawa, Tatsuhiro Ohata, Hirotaka Ikeda, Hajime Matsumoto, Yutaka Mikawa
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Patent number: 10720326Abstract: A method for growing a GaN crystal suitable as a material of GaN substrates including C-plane GaN substrates includes: a first step of preparing a GaN seed having a nitrogen polar surface; a second step of arranging a pattern mask on the nitrogen polar surface of the GaN seed, the pattern mask being provided with a periodical opening pattern comprising linear openings and including intersections, the pattern mask being arranged such that longitudinal directions of at least part of the linear openings are within ±3° from a direction of an intersection line between the nitrogen polar surface and an M-plane; and a third step of ammonothermally growing a GaN crystal through the pattern mask such that a gap is formed between the GaN crystal and the pattern mask.Type: GrantFiled: February 7, 2019Date of Patent: July 21, 2020Assignee: MITSUBISHI CHEMICAL CORPORATIONInventors: Yutaka Mikawa, Hideo Fujisawa, Tae Mochizuki, Hideo Namita, Shinichiro Kawabata
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Patent number: 10655244Abstract: A disc-like GaN substrate is a substrate produced by a tiling method and having an angel between the normal line and m-axis on the main surface of the substrate of 0 to 20° inclusive and a diameter of 45 to 55 mm, to 4 or less. In a preferred embodiment, a disc-like GaN substrate has a first main surface and a second main surface that is opposite to the first main surface, and which has an angle between the normal line and m-axis on the first main surface of 0 to 20° inclusive and a diameter of 45 mm or more. The disc-like GaN substrate comprises at least four crystalline regions each being exposed to both of the first main surface and the second main surface, wherein the four crystalline regions are arranged in line along the direction of the orthogonal projection of c-axis on the first main surface.Type: GrantFiled: July 13, 2018Date of Patent: May 19, 2020Assignee: MITSUBISHI CHEMICAL CORPORATIONInventors: Yusuke Tsukada, Satoru Nagao, Kazunori Kamada, Masayuki Tashiro, Kenji Fujito, Hideo Fujisawa, Yutaka Mikawa, Tetsuharu Kajimoto, Takashi Fukada
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Publication number: 20200109489Abstract: A high-quality nitride crystal can be produced efficiently by charging a nitride crystal starting material that contains tertiary particles having a maximum diameter of from 1 to 120 mm and formed through aggregation of secondary particles having a maximum diameter of from 100 to 1000 ?m, in the starting material charging region of a reactor, followed by crystal growth in the presence of a solvent in a supercritical state and/or a subcritical state in the reactor, wherein the nitride crystal starting material is charged in the starting material charging region in a bulk density of from 0.7 to 4.5 g/cm3 for the intended crystal growth.Type: ApplicationFiled: October 28, 2019Publication date: April 9, 2020Applicant: MITSUBISHI CHEMICAL CORPORATIONInventors: Yutaka MIKAWA, Hideo FUJISAWA, Kazunori KAMADA, Hirobumi NAGAOKA, Shinichiro KAWABATA, Yuji KAGAMITANI
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Publication number: 20200013860Abstract: An object is to provide a nonpolar or semipolar GaN substrate having improved size and crystal quality. A self-standing GaN substrate has an angle between the normal of the principal surface and an m-axis of 0 degrees or more and 20 degrees or less, wherein: the size of the projected image in a c-axis direction when the principal surface is vertically projected on an M-plane is 10 mm or more; and when an a-axis length is measured on an intersection line between the principal surface and an A-plane, a low distortion section with a section length of 6 mm or more and with an a-axis length variation within the section of 10.0×10?5 ? or less is observed.Type: ApplicationFiled: September 18, 2019Publication date: January 9, 2020Applicant: Mitsubishi Chemical CorporationInventors: Satoru NAGAO, Yusuke Tsukada, Kazunori Kamada, Shuichi Kubo, Hirotaka Ikeda, Kenji Fujito, Hideo Fujisawa, Yutaka Mikawa, Tae Mochizuki
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Patent number: 10526726Abstract: A high-quality nitride crystal can be produced efficiently by charging a nitride crystal starting material that contains tertiary particles having a maximum diameter of from 1 to 120 mm and formed through aggregation of secondary particles having a maximum diameter of from 100 to 1000 ?m, in the starting material charging region of a reactor, followed by crystal growth in the presence of a solvent in a supercritical state and/or a subcritical state in the reactor, wherein the nitride crystal starting material is charged in the starting material charging region in a bulk density of from 0.7 to 4.5 g/cm3 for the intended crystal growth.Type: GrantFiled: November 9, 2016Date of Patent: January 7, 2020Assignee: MITSUBISHI CHEMICAL CORPORATIONInventors: Yutaka Mikawa, Hideo Fujisawa, Kazunori Kamada, Hirobumi Nagaoka, Shinichiro Kawabata, Yuji Kagamitani
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Patent number: 10475887Abstract: An object is to provide a nonpolar or semipolar GaN substrate having improved size and crystal quality. A self-standing GaN substrate has an angle between the normal of the principal surface and an m-axis of 0 degrees or more and 20 degrees or less, wherein: the size of the projected image in a c-axis direction when the principal surface is vertically projected on an M-plane is 10 mm or more; and when an a-axis length is measured on an intersection line between the principal surface and an A-plane, a low distortion section with a section length of 6 mm or more and with an a-axis length variation within the section of 10.0×10?5 ? or less is observed.Type: GrantFiled: February 5, 2016Date of Patent: November 12, 2019Assignee: Mitsubishi Chemical CorporationInventors: Satoru Nagao, Yusuke Tsukada, Kazunori Kamada, Shuichi Kubo, Hirotaka Ikeda, Kenji Fujito, Hideo Fujisawa, Yutaka Mikawa, Tae Mochizuki
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Publication number: 20190312111Abstract: An object is to provide a nonpolar or semipolar GaN substrate having improved size and crystal quality. A self-standing GaN substrate has an angle between the normal of the principal surface and an m-axis of 0 degrees or more and 20 degrees or less, wherein: the size of the projected image in a c-axis direction when the principal surface is vertically projected on an M-plane is 10 mm or more; and when an a-axis length is measured on an intersection line between the principal surface and an A-plane, a low distortion section with a section length of 6 mm or more and with an a-axis length variation within the section of 10.0×10?5 ? or less is observed.Type: ApplicationFiled: June 18, 2019Publication date: October 10, 2019Applicant: Mitsubishi Chemical CorporationInventors: Satoru NAGAO, Yusuke TSUKADA, Kazunori KAMADA, Shuichi KUBO, Hirotaka IKEDA, Kenji FUJITO, Hideo FUJISAWA, Yutaka MIKAWA, Tae MOCHIZUKI
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Publication number: 20190203379Abstract: An object of the present invention is to provide a crystal of a nitride of a Group-13 metal on the Periodic Table which has good crystallinity and has no crystal strain, and to provide a production method for the crystal. The crystal of a nitride of a Group-13 metal on the Periodic Table of the present invention, comprises oxygen atom and hydrogen atom in the crystal and has a ratio of a hydrogen concentration to an oxygen concentration therein of from 0.5 to 4.5.Type: ApplicationFiled: March 8, 2019Publication date: July 4, 2019Applicant: MITSUBISHI CHEMICAL CORPORATIONInventors: Yutaka Mikawa, Hideo Namita, Hirotaka Ikeda, Kazunori Kamada, Hideo Fujisawa, Atsuhiko Kojima
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Publication number: 20190189439Abstract: A method for growing a GaN crystal suitable as a material of GaN substrates including C-plane GaN substrates includes: a first step of preparing a GaN seed having a nitrogen polar surface; a second step of arranging a pattern mask on the nitrogen polar surface of the GaN seed, the pattern mask being provided with a periodical opening pattern comprising linear openings and including intersections, the pattern mask being arranged such that longitudinal directions of at least part of the linear openings are within ±3° from a direction of an intersection line between the nitrogen polar surface and an M-plane; and a third step of ammonothermally growing a GaN crystal through the pattern mask such that a gap is formed between the GaN crystal and the pattern mask.Type: ApplicationFiled: February 7, 2019Publication date: June 20, 2019Applicant: MITSUBISHI CHEMICAL CORPORATIONInventors: Yutaka MIKAWA, Hideo FUJISAWA, Tae MOCHIZUKI, Hideo NAMITA, Shinichiro KAWABATA
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Publication number: 20190189438Abstract: A conductive C-plane GaN substrate has a resistivity of 2×10?2 ?·cm or less or an n-type carrier concentration of 1×1018 cm?3 or more at room temperature. At least one virtual line segment with a length of 40 mm can be drawn at least on one main surface of the substrate. The line segment satisfies at least one of the following conditions (A1) and (B1): (A1) when an XRC of (004) reflection is measured at 1 mm intervals on the line segment, a maximum value of XRC-FWHMs across all measurement points is less than 30 arcsec; and (B1) when an XRC of the (004) reflection is measured at 1 mm intervals on the line segment, a difference between maximum and minimum values of XRC peak angles across all the measurement points is less than 0.2°.Type: ApplicationFiled: February 7, 2019Publication date: June 20, 2019Applicant: MITSUBISHI CHEMICAL CORPORATIONInventors: Yutaka MIKAWA, Hideo FUJISAWA, Tae MOCHIZUKI, Hideo NAMITA, Shinichiro KAWABATA
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Patent number: 10309038Abstract: An object of the present invention is to provide a crystal of a nitride of a Group-13 metal on the Periodic Table which has good crystallinity and has no crystal strain, and to provide a production method for the crystal. The crystal of a nitride of a Group-13 metal on the Periodic Table of the present invention, comprises oxygen atom and hydrogen atom in the crystal and has a ratio of a hydrogen concentration to an oxygen concentration therein of from 0.5 to 4.5.Type: GrantFiled: December 14, 2017Date of Patent: June 4, 2019Assignee: MITSUBISHI CHEMICAL CORPORATIONInventors: Yutaka Mikawa, Hideo Namita, Hirotaka Ikeda, Kazunori Kamada, Hideo Fujisawa, Atsuhiko Kojima
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Patent number: 10301743Abstract: A new GaN single crystal is provided. A GaN single crystal according to the present embodiment comprises a gallium polar surface which is a main surface on one side and a nitrogen polar surface which is a main surface on the opposite side, wherein on the gallium polar surface is found at least one square area, an outer periphery of which is constituted by four sides each with a length of 2 mm or more, and, when the at least one square are is divided into a plurality of sub-areas each of which is a square of 100 ?m×100 ?m, pit-free areas account for 80% or more of the sub-areas.Type: GrantFiled: July 28, 2017Date of Patent: May 28, 2019Assignee: MITSUBISHI CHEMICAL CORPORATIONInventors: Hideo Fujisawa, Yutaka Mikawa, Shinichiro Kawabata, Hideo Namita, Tae Mochizuki
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Publication number: 20190127881Abstract: A new GaN single crystal is provided. A GaN single crystal according to the present embodiment comprises a gallium polar surface which is a main surface on one side and a nitrogen polar surface which is a main surface on the opposite side, wherein on the gallium polar surface is found at least one square area, an outer periphery of which is constituted by four sides each with a length of 2 mm or more, and, when the at least one square are is divided into a plurality of sub-areas each of which is a square of 100 ?m×100 ?m, pit-free areas account for 80% or more of the sub-areas.Type: ApplicationFiled: November 20, 2018Publication date: May 2, 2019Applicant: MITSUBISHI CHEMICAL CORPORATIONInventors: Hideo FUJISAWA, Yutaka MIKAWA, Shinichiro KAWABATA, Hideo NAMITA, Tae MOCHIZUKI