Patents by Inventor Mikiya Ichimura

Mikiya Ichimura 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: 10804432
    Abstract: A free-standing substrate of a polycrystalline nitride of a group 13 element contains a plurality of monocrystalline particles having a particular crystal orientation in approximately a normal direction. The polycrystalline nitride of the group 13 element is composed of gallium nitride, aluminum nitride, indium nitride or a mixed crystal thereof. The free-standing substrate has a top surface and bottom surface. The free-standing substrate contains at least one of zinc and calcium. A root mean square roughness Rms at the top surface is 3.0 nm or less.
    Type: Grant
    Filed: August 9, 2018
    Date of Patent: October 13, 2020
    Assignee: NGK INSULATORS, LTD.
    Inventors: Katsuhiro Imai, Yoshitaka Kuraoka, Mikiya Ichimura, Takayuki Hirao
  • Patent number: 10770552
    Abstract: An epitaxial substrate for semiconductor elements suppresses leakage current and has a high breakdown voltage. The epitaxial substrate for semiconductor elements includes: a semi-insulating free-standing substrate formed of GaN doped with Zn; a buffer layer formed of a group 13 nitride adjacent to the free-standing substrate; a channel layer formed of a group 13 nitride adjacent to the buffer layer; and a barrier layer formed of a group 13 nitride on an opposite side of the buffer layer with the channel layer therebetween, wherein part of a first region consisting of the free-standing substrate and the buffer layer is a second region containing Si at a concentration of 1×1017cm?3 or more, and a minimum value of a concentration of Zn in the second region is 1×1017cm?3.
    Type: Grant
    Filed: January 3, 2020
    Date of Patent: September 8, 2020
    Assignee: NGK INSULATORS, LTD.
    Inventors: Mikiya Ichimura, Sota Maehara, Yoshitaka Kuraoka
  • Patent number: 10734548
    Abstract: A free-standing substrate of a polycrystalline nitride of a group 13 element is composed of a plurality of monocrystalline particles having a particular crystal orientation in approximately a normal direction. The free-standing substrate has a top surface and a bottom surface. The polycrystalline nitride of the group 13 element is gallium nitride, aluminum nitride, indium nitride or a mixed crystal thereof and contains zinc at a concentration of 1×1017 atoms/cm3 or more and 1×1020 atoms/cm3 or less.
    Type: Grant
    Filed: August 9, 2018
    Date of Patent: August 4, 2020
    Assignee: NGK INSULATORS, LTD.
    Inventors: Katsuhiro Imai, Yoshitaka Kuraoka, Mikiya Ichimura, Takayuki Hirao
  • Publication number: 20200232120
    Abstract: A layer of a crystal of a group 13 nitride selected from gallium nitride, aluminum nitride, indium nitride and the mixed crystals thereof has an upper surface and a bottom surface. The upper surface of a crystal layer of the group 13 nitride includes a linear high-luminance light-emitting part and a low-luminance light-emitting region adjacent to the high-luminance light-emitting part, observed by cathode luminescence. The high-luminance light-emitting part includes a portion extending along an m-plane of the crystal of the group 13 nitride. A normal line to the upper surface has an off-angle of 2.0° or less with respect to <0001> direction of the crystal of the nitride of the group 13 element.
    Type: Application
    Filed: February 21, 2020
    Publication date: July 23, 2020
    Inventors: Takayuki HIRAO, Hirokazu NAKANISHI, Mikiya ICHIMURA, Takanao SHIMODAIRA, Masahiro SAKAI, Takashi YOSHINO
  • Publication number: 20200203573
    Abstract: It is provided a layer of a crystal of a nitride of a group 13 element selected from gallium nitride, aluminum nitride, indium nitride and the mixed crystals thereof, and the layer includes an upper surface and a bottom surface. The upper surface includes a linear high-luminance light-emitting part and a low-luminance light-emitting region adjacent to the high-luminance light-emitting part, and the high-luminance light-emitting part has a portion extending along an m-plane of the crystal of the nitride of the group 13 element, in the case that the upper surface is observed by cathode luminescence. The upper surface has an arithmetic average roughness Ra of 0.05 nm or more and 1.0 nm or less.
    Type: Application
    Filed: February 21, 2020
    Publication date: June 25, 2020
    Inventors: Takayuki HIRAO, Hirokazu NAKANISHI, Mikiya ICHIMURA, Takanao SHIMODAIRA, Masahiro SAKAI, Takashi YOSHINO
  • Publication number: 20200194621
    Abstract: A layer of a crystal of a group 13 nitride selected from gallium nitride, aluminum nitride, indium nitride and the mixed crystals thereof has an upper surface and a bottom surface. The upper surface of a crystal layer of the group 13 nitride includes a linear high-luminance light-emitting part and a low-luminance light-emitting region adjacent to the high-luminance light-emitting part, observed by cathode luminescence. The high-luminance light-emitting part includes a portion extending along an m-plane of the crystal of the group 13 nitride. The crystal of the nitride of the group 13 element contains oxygen atoms in a content of 1×1018 atom/cm3 or less, silicon atoms, manganese atoms, carbon atoms, magnesium atoms and calcium atoms in contents of 1×1017 atom/cm3 or less, chromium atoms in a content of 1×1016 atom/cm3 or less and chlorine atoms in a content of 1×1015 atom/cm3 or less.
    Type: Application
    Filed: February 21, 2020
    Publication date: June 18, 2020
    Inventors: Takayuki HIRAO, Hirokazu NAKANISHI, Mikiya ICHIMURA, Takanao SHIMODAIRA, Masahiro SAKAI, Takashi YOSHINO
  • Publication number: 20200190695
    Abstract: It is provided a layer of a crystal of a group 13 nitride having an upper surface and lower surface and composed of a crystal of the group 13 nitride selected from gallium nitride, aluminum nitride, indium nitride or the mixed crystals thereof. In the case that the upper surface of the layer of the crystal of the group 13 nitride is observed by cathode luminescence, the upper surface includes a linear high-luminance light-emitting part and a low-luminance light-emitting region adjacent to the high-luminance light-emitting part. A half value width of reflection at (0002) plane of an X-ray rocking curve on the upper surface is 3000 seconds or less and 20 seconds or more.
    Type: Application
    Filed: February 21, 2020
    Publication date: June 18, 2020
    Inventors: Takayuki HIRAO, Hirokazu NAKANISHI, Mikiya ICHIMURA, Takanao SHIMODAIRA, Masahiro SAKAI, Takashi YOSHINO
  • Publication number: 20200194626
    Abstract: A layer of a crystal of a group 13 nitride selected from gallium nitride, aluminum nitride, indium nitride and the mixed crystals thereof has an upper surface and a bottom surface. The upper surface of a crystal layer of the group 13 nitride includes a linear high-luminance light-emitting part and a low-luminance light-emitting region adjacent to the high-luminance light-emitting part, observed by cathode luminescence. The high-luminance light-emitting part includes a portion extending along an m-plane of the crystal of the group 13 nitride.
    Type: Application
    Filed: February 21, 2020
    Publication date: June 18, 2020
    Inventors: Takayuki HIRAO, Hirokazu NAKANISHI, Mikiya ICHIMURA, Takanao SHIMODAIRA, Masahiro SAKAI, Takashi YOSHINO
  • Publication number: 20200144373
    Abstract: An epitaxial substrate for semiconductor elements suppresses leakage current and has a high breakdown voltage. The epitaxial substrate for semiconductor elements includes: a semi-insulating free-standing substrate formed of GaN doped with Zn; a buffer layer formed of a group 13 nitride adjacent to the free-standing substrate; a channel layer formed of a group 13 nitride adjacent to the buffer layer; and a barrier layer formed of a group 13 nitride on an opposite side of the buffer layer with the channel layer therebetween, wherein part of a first region consisting of the free-standing substrate and the buffer layer is a second region containing Si at a concentration of 1×1017cm?3 or more, and a minimum value of a concentration of Zn in the second region is 1×1017cm?3.
    Type: Application
    Filed: January 3, 2020
    Publication date: May 7, 2020
    Inventors: Mikiya ICHIMURA, Sota MAEHARA, Yoshitaka KURAOKA
  • Patent number: 10629688
    Abstract: An epitaxial substrate for semiconductor elements suppresses leakage current and has a high breakdown voltage. The epitaxial substrate for semiconductor elements includes: a semi-insulating free-standing substrate formed of GaN doped with Zn; a buffer layer formed of a group 13 nitride adjacent to the free-standing substrate; a channel layer formed of a group 13 nitride adjacent to the buffer layer; and a barrier layer formed of a group 13 nitride on an opposite side of the buffer layer with the channel layer therebetween, wherein part of a first region consisting of the free-standing substrate and the buffer layer is a second region containing Si at a concentration of 1×1017 cm?3 or more, and a minimum value of a concentration of Zn in the second region is 1×1017 cm?3.
    Type: Grant
    Filed: April 25, 2018
    Date of Patent: April 21, 2020
    Assignee: NGK INSULATORS, LTD.
    Inventors: Mikiya Ichimura, Sota Maehara, Yoshitaka Kuraoka
  • Patent number: 10580646
    Abstract: An epitaxial substrate for semiconductor elements is provided which suppresses the occurrence of current collapse. The epitaxial substrate for the semiconductor elements includes: a semi-insulating free-standing substrate formed of GaN doped with Zn; a buffer layer adjacent to the free-standing substrate; a channel layer adjacent to the buffer layer; and a barrier layer provided on an opposite side of the buffer layer with the channel layer therebetween, wherein the buffer layer is a diffusion suppressing layer formed of AlpGa1-pN (0.7?p?1) and suppresses diffusion of Zn from the free-standing substrate into the channel layer.
    Type: Grant
    Filed: April 27, 2018
    Date of Patent: March 3, 2020
    Assignee: NGK INSULATORS, LTD.
    Inventors: Mikiya Ichimura, Sota Maehara, Yoshitaka Kuraoka
  • Patent number: 10418239
    Abstract: Provided is an epitaxial substrate for semiconductor elements which suppresses an occurrence of current collapse. The epitaxial substrate for the semiconductor elements includes: a semi-insulating free-standing substrate formed of GaN being doped with Zn; a buffer layer being adjacent to the free-standing substrate; a channel layer being adjacent to the buffer layer; and a barrier layer being provided on an opposite side of the buffer layer with the channel layer therebetween, wherein the buffer layer is a diffusion suppressing layer formed of Al-doped GaN and suppresses diffusion of Zn from the free-standing substrate into the channel layer.
    Type: Grant
    Filed: April 27, 2018
    Date of Patent: September 17, 2019
    Assignee: NGK INSULATORS, LTD.
    Inventors: Mikiya Ichimura, Sota Maehara, Yoshitaka Kuraoka
  • Patent number: 10410859
    Abstract: An epitaxial substrate for semiconductor elements which suppresses the occurrence of current collapse. The epitaxial substrate for the semiconductor elements includes: a semi-insulating free-standing substrate formed of GaN doped with Zn; a buffer layer adjacent to the free-standing substrate; a channel layer adjacent to the buffer layer; and a barrier layer provided on an opposite side of the buffer layer with the channel layer provided therebetween, wherein the buffer layer is a diffusion suppressing layer that suppresses the diffusion of Zn from the free-standing substrate into the channel layer.
    Type: Grant
    Filed: April 27, 2018
    Date of Patent: September 10, 2019
    Assignee: NGK INSULATORS, LTD.
    Inventors: Mikiya Ichimura, Sota Maehara, Yoshitaka Kuraoka
  • Patent number: 10347755
    Abstract: Provided are a group 13 nitride composite substrate allowing for the production of a semiconductor device suitable for high-frequency applications while including a conductive GaN substrate, and a semiconductor device produced using this substrate. The group 13 nitride composite substrate includes a base material of an n-conductivity type formed of GaN, a base layer located on the base material, being a group 13 nitride layer having a resistivity of 1×106 ?·cm or more, a channel layer located on the base layer, being a GaN layer having a total impurity density of 1×1017/cm3 or less, and a barrier layer that is located on the channel layer and is formed of a group 13 nitride having a composition AlxInyGa1-x-yN (0?x?1, 0?y?1).
    Type: Grant
    Filed: November 18, 2016
    Date of Patent: July 9, 2019
    Assignee: NGK INSULATORS, LTD.
    Inventors: Yoshitaka Kuraoka, Mikiya Ichimura, Makoto Iwai
  • Patent number: 10332975
    Abstract: Provided is a group 13 nitride epitaxial substrate with which the HEMT device having superior characteristics can be manufactured. This epitaxial substrate is provided with: a base substrate composed of SiC and having a main surface with a (0001) plane orientation; a nucleation layer formed on one main surface of the base substrate and composed of AlN; an electron transit layer formed on the nucleation layer and composed of a group 13 nitride with the composition AlyGa1-yN (0?y<1); and a barrier layer formed on the electron transit layer and composed of a group 13 nitride with the composition InzAl1-zN (0.13?z?0.23) or AlwGa1-wN (0.15?w?0.35). The (0001) plane of the base substrate has an off angle of 0.1° or more and 0.5° or less, and an intermediate layer composed of a group 13 nitride with the composition AlxGa1-xN (0.01 ?x?0.4) is further provided between the nucleation layer and the electron transit layer.
    Type: Grant
    Filed: March 24, 2017
    Date of Patent: June 25, 2019
    Assignee: NGK INSULATORS, LTD.
    Inventors: Mikiya Ichimura, Sota Maehara, Yoshitaka Kuraoka
  • Patent number: 10332958
    Abstract: A supporting substrate for a composite substrate comprises a ceramic and has a polished surface for use in bonding. An orientation degree of the ceramic forming the supporting substrate at the polished surface is 50% or higher, and an aspect ratio of each crystal grain included in the supporting substrate is 5.0 or less.
    Type: Grant
    Filed: October 28, 2015
    Date of Patent: June 25, 2019
    Assignee: NGK Insulators, Ltd.
    Inventors: Jun Yoshikawa, Mikiya Ichimura, Katsuhiro Imai
  • Publication number: 20190027359
    Abstract: Provided is an epitaxial substrate for semiconductor elements which suppresses an occurrence of current collapse. The epitaxial substrate for the semiconductor elements includes: a semi-insulating free-standing substrate formed of GaN being doped with Zn; a buffer layer being adjacent to the free-standing substrate; a channel layer being adjacent to the buffer layer; and a barrier layer being provided on an opposite side of the buffer layer with the channel layer therebetween, wherein the buffer layer is a diffusion suppressing layer that suppresses diffusion of Zn from the free-standing substrate into the channel layer.
    Type: Application
    Filed: April 27, 2018
    Publication date: January 24, 2019
    Inventors: Mikiya ICHIMURA, Sota MAEHARA, Yoshitaka KURAOKA
  • Publication number: 20180350918
    Abstract: A free-standing substrate of a polycrystalline nitride of a group 13 element contains a plurality of monocrystalline particles having a particular crystal orientation in approximately a normal direction. The polycrystalline nitride of the group 13 element is composed of gallium nitride, aluminum nitride, indium nitride or a mixed crystal thereof. The free-standing substrate has a top surface and bottom surface. The free-standing substrate contains at least one of zinc and calcium. A root mean square roughness Rms at the top surface is 3.0 nm or less.
    Type: Application
    Filed: August 9, 2018
    Publication date: December 6, 2018
    Inventors: Katsuhiro IMAI, Yoshitaka KURAOKA, Mikiya ICHIMURA, Takayuki HIRAO
  • Publication number: 20180351041
    Abstract: A free-standing substrate of a polycrystalline nitride of a group 13 element is composed of a plurality of monocrystalline particles having a particular crystal orientations in approximately a normal direction. The free-standing substrate has a top surface and a bottom surface. The polycrystalline nitride of the group 13 element is gallium nitride, aluminum nitride, indium nitride or a mixed crystal thereof and contains zinc at a concentration of 1×1017 atoms/cm3 or more and 1×1020 atoms/cm3 or less.
    Type: Application
    Filed: August 9, 2018
    Publication date: December 6, 2018
    Inventors: Katsuhiro IMAI, Yoshitaka KURAOKA, Mikiya ICHIMURA, Takayuki HIRAO
  • Patent number: 10128406
    Abstract: A device substrate in which no streaked morphological abnormality occurs is achieved. A GaN template substrate includes: a base substrate; and a first GaN layer epitaxially formed on the base substrate, wherein the first GaN layer has a compressive stress greater than or equal to 260 MPa that is intrinsic in an inplane direction, or a full width at half maximum of a peak representing E2 phonons of GaN near a wavenumber of 568 cm?1 in a Raman spectrum is lower than or equal to 1.8 cm?1. With all of these requirements, a device substrate includes: a second GaN layer epitaxially formed on the first GaN layer; and a device layer epitaxially formed on the second GaN layer and made of a group 13 nitride.
    Type: Grant
    Filed: April 15, 2016
    Date of Patent: November 13, 2018
    Assignee: NGK INSULATORS, LTD.
    Inventors: Mikiya Ichimura, Yoshitaka Kuraoka, Masahiko Namerikawa