Patents by Inventor Yoshitaka Kadowaki

Yoshitaka Kadowaki 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: 11894502
    Abstract: A method of manufacturing a semiconductor optical device of this disclosure includes the steps of forming an etch stop layer on an InP growth substrate, the etch stop layer having a thickness of 100 nm or less; and forming a semiconductor laminate on the etch stop layer by stacking a plurality of InGaAsP-based III-V group compound semiconductor layers containing at least In and P. Further, an intermediate article of a semiconductor optical device of the present disclosure includes an InP growth substrate; an etch stop layer formed on the InP growth substrate, the etch stop layer having a thickness of 100 nm or less; and a semiconductor laminate formed on the etch stop layer, including a plurality of InGaAsP-based III-V group compound semiconductor layers containing at least In and P stacked one another.
    Type: Grant
    Filed: March 27, 2019
    Date of Patent: February 6, 2024
    Assignee: DOWA Electronics Materials Co., Ltd.
    Inventors: Yuta Koshika, Yoshitaka Kadowaki, Tetsuya Ikuta
  • Patent number: 11888090
    Abstract: Provided is a semiconductor light-emitting element having improved light emission output. The semiconductor light-emitting element includes a light-emitting layer having a layered structure in which a first III-V compound semiconductor layer and a second III-V compound semiconductor layer having different composition ratios are repeatedly stacked. The first and second III-V compound semiconductor layers each contain three or more types of elements that are selected from Al, Ga, and In and from As, Sb, and P. The composition wavelength difference between the composition wavelength of the first III-V compound semiconductor layer and the composition wavelength of the second III-V compound semiconductor layer is 50 nm or less. The ratio of the lattice constant difference between the lattice constant of the first III-V compound semiconductor layer and the lattice constant of the second III-V compound semiconductor layer is not less than 0.05% and not more than 0.60%.
    Type: Grant
    Filed: December 12, 2019
    Date of Patent: January 30, 2024
    Assignee: DOWA Electronics Materials Co., Ltd.
    Inventors: Yuta Koshika, Yoshitaka Kadowaki
  • Publication number: 20230155061
    Abstract: Provided is a semiconductor light-emitting element that exhibits a light emission spectrum in which a single peak is obtained by controlling multi peaks. In the semiconductor light-emitting element having a second conductivity type cladding layer on the light extraction side, the arithmetic mean roughness Ra of a surface of the light extraction surface of the second conductivity type cladding layer is 0.07 ?m or more and 0.7 ?m or less, and the skewness Rsk of the surface is a positive value.
    Type: Application
    Filed: October 13, 2020
    Publication date: May 18, 2023
    Applicant: DOWA Electronics Materials Co., Ltd.
    Inventors: Osamu TANAKA, Yoshitaka KADOWAKI
  • Publication number: 20220406967
    Abstract: To improve light emission efficiency, in a light-emitting element including a first InAs layer that is undoped or doped with an n-type dopant; an active layer including one or more InAsySb1-y layers (0<y<1); and a second InAs layer doped with a p-type dopant, an AlxIn1-xAs electron blocking layer (0.05?x?0.40) with a thickness of 5 nm to 40 nm is provided between the active layer and the second InAs layer.
    Type: Application
    Filed: October 23, 2020
    Publication date: December 22, 2022
    Applicant: DOWA Electronics Materials Co., Ltd.
    Inventors: Yoshitaka KADOWAKI, Shogo SAKURABA, Osamu TANAKA
  • Publication number: 20220367749
    Abstract: Provided is a method of producing a semiconductor optical device that makes it possible to improve the optical device properties of the semiconductor optical device including semiconductor layers containing at least In, As, and Sb. The method has a first step of forming an etching stop layer on an InAs growth substrate; a second step of forming a semiconductor laminate; a third step of forming a distribution portion; a fourth step of bonding the semiconductor laminate and the distribution portion to a support substrate with a metal bonding layer therebetween; and a fifth step of removing the InAs growth substrate.
    Type: Application
    Filed: June 16, 2020
    Publication date: November 17, 2022
    Applicant: DOWA Electronics Materials Co., Ltd.
    Inventors: Yoshitaka KADOWAKI, Osamu TANAKA
  • Publication number: 20220059721
    Abstract: Provided is a semiconductor light-emitting element having improved light emission output. The semiconductor light-emitting element includes a light-emitting layer having a layered structure in which a first III-V compound semiconductor layer and a second III-V compound semiconductor layer having different composition ratios are repeatedly stacked. The first and second III-V compound semiconductor layers each contain three or more types of elements that are selected from Al, Ga, and In and from As, Sb, and P. The composition wavelength difference between the composition wavelength of the first III-V compound semiconductor layer and the composition wavelength of the second III-V compound semiconductor layer is 50 nm or less. The ratio of the lattice constant difference between the lattice constant of the first III-V compound semiconductor layer and the lattice constant of the second III-V compound semiconductor layer is not less than 0.05% and not more than 0.60%.
    Type: Application
    Filed: December 12, 2019
    Publication date: February 24, 2022
    Applicant: DOWA Electronics Materials Co., Ltd.
    Inventors: Yuta KOSHIKA, Yoshitaka KADOWAKI
  • Publication number: 20210020814
    Abstract: A method of manufacturing a semiconductor optical device of this disclosure includes the steps of forming an etch stop layer on an InP growth substrate, the etch stop layer having a thickness of 100 nm or less; and forming a semiconductor laminate on the etch stop layer by stacking a plurality of InGaAsP-based III-V group compound semiconductor layers containing at least In and P. Further, an intermediate article of a semiconductor optical device of the present disclosure includes an InP growth substrate; an etch stop layer formed on the InP growth substrate, the etch stop layer having a thickness of 100 nm or less; and a semiconductor laminate formed on the etch stop layer, including a plurality of InGaAsP-based III-V group compound semiconductor layers containing at least In and P stacked one another.
    Type: Application
    Filed: March 27, 2019
    Publication date: January 21, 2021
    Applicant: DOWA Electronics Materials Co., Ltd.
    Inventors: Yuta KOSHIKA, Yoshitaka KADOWAKI, Tetsuya IKUTA
  • Patent number: 9537053
    Abstract: Provided is a high quality III nitride semiconductor device in which, not only X-shaped cracks extending from the vicinity of the corners of semiconductor structures to the center portion thereof, but also crack spots at the center portion can be prevented from being formed and can provide a method of efficiently manufacturing the III nitride semiconductor device. The III nitride semiconductor device of the present invention includes a support and two semiconductor structures having a nearly quadrangular transverse cross-sectional shape that are provided on the support. The two semiconductor structures are situated such that one side surface of one of the two semiconductor structures is placed to face one side surface of the other of them. The support covers the other three side surfaces and of the four sides of the semiconductor structures.
    Type: Grant
    Filed: September 28, 2012
    Date of Patent: January 3, 2017
    Assignees: BBSA LIMITED, DOWA ELECTRONICS MATERIALS CO., LTD.
    Inventors: Meoung Whan Cho, Seog Woo Lee, Ryuichi Toba, Yoshitaka Kadowaki
  • Patent number: 9537066
    Abstract: When an uneven pattern is formed on a light extraction surface composed of a semiconductor crystal by wet-etching using an alkaline solution, a plurality of convex portions cannot be formed in a desired arrangement. A method of manufacturing a semiconductor light emitting device includes a light extraction surface composed of a semiconductor crystal, wherein when the uneven pattern is formed by a plurality of convex portions on the light extraction surface, first, a plurality of impressions are formed on the light extraction surface of a semiconductor layer composed of a semiconductor crystal using a processing substrate, and next, by applying wet-etching to the light extraction surface using an alkaline solution, to thereby form convex portions with a portion where each impression is formed as a top portion, and a plurality of facets of the semiconductor crystal as a side face thereof.
    Type: Grant
    Filed: July 30, 2014
    Date of Patent: January 3, 2017
    Assignee: DOWA ELECTRONICS MATERIALS CO., LTD.
    Inventor: Yoshitaka Kadowaki
  • Patent number: 9502603
    Abstract: A method for manufacturing a vertically structured Group III nitride semiconductor LED chip includes a first step of forming a light emitting structure laminate; a second step of forming a plurality of separate light emitting structures by partially removing the light emitting structure laminate to partially expose the growth substrate; a third step of forming a conductive support, which conductive support integrally supporting the light emitting structures; a fourth step of separating the growth substrate by removing the lift-off layer; and a fifth step of dividing the conductive support between the light emitting structures thereby singulating a plurality of LED chips each having the light emitting structure. A first through-hole is formed to open in a central region of each of the light emitting structures such that at least the lift-off layer is exposed, and an etchant is supplied from the first through-hole in the fourth step.
    Type: Grant
    Filed: May 12, 2011
    Date of Patent: November 22, 2016
    Assignees: WAVESQUARE INC., DOWA ELECTRONICS MATERIALS CO., LTD.
    Inventors: Meoung Whan Cho, Seog Woo Lee, Pil Guk Jang, Ryuichi Toba, Yoshitaka Kadowaki
  • Publication number: 20160197251
    Abstract: When an uneven pattern is formed on a light extraction surface composed of a semiconductor crystal by wet-etching using an alkaline solution, a plurality of convex portions cannot be formed in a desired arrangement. A method of manufacturing a semiconductor light emitting device includes a light extraction surface composed of a semiconductor crystal, wherein when the uneven pattern is formed by a plurality of convex portions on the light extraction surface, first, a plurality of impressions are formed on the light extraction surface of a semiconductor layer composed of a semiconductor crystal using a processing substrate, and next, by applying wet-etching to the light extraction surface using an alkaline solution, to thereby form convex portions with a portion where each impression is formed as a top portion, and a plurality of facets of the semiconductor crystal as a side face thereof.
    Type: Application
    Filed: July 30, 2014
    Publication date: July 7, 2016
    Applicant: DOWA ELECTRONICS MATERIALS CO., LTD.
    Inventor: Yoshitaka KADOWAKI
  • Patent number: 9318653
    Abstract: A luminescent device and a manufacturing method for the luminescent device and a semiconductor device which are free from occurrence of cracks in a compound semiconductor layer due to the internal stress in the compound semiconductor layer at the time of chemical lift-off. The luminescent device manufacturing method includes forming a device region on part of an epitaxial substrate through a lift-off layer; forming a sacrificing portion, being not removed in a chemical lift-off step, around device region on epitaxial substrate; covering epitaxial substrate and semiconductor layer and forming a covering layer such that level of surface thereof in the region away from device region is lower than luminescent layer surface; removing covering layer on semiconductor layer, and that on sacrificing portion surface; forming a reflection layer on covering layer surface and semiconductor layer surface; and forming a supporting substrate by providing plating on reflection layer.
    Type: Grant
    Filed: May 29, 2015
    Date of Patent: April 19, 2016
    Assignee: DOWA ELECTRONICS MATERIALS CO., LTD.
    Inventors: Yoshitaka Kadowaki, Tatsunori Toyota
  • Patent number: 9287366
    Abstract: Provided are a III nitride semiconductor device which can be operated at a lower voltage can be provided, in which device a good ohmic contact is achieved between the (000-1) plane side of the III nitride semiconductor layer and the electrode and a method of producing the III nitride semiconductor device. A III nitride semiconductor device of the present invention includes a plurality of protrusions rounded like domes in a predetermined region on the (000-1) plane side of the III nitride semiconductor layer; and an electrode on the upper surface of the predetermined region.
    Type: Grant
    Filed: December 12, 2012
    Date of Patent: March 15, 2016
    Assignee: DOWA ELECTRONICS MATERIALS CO., LTD.
    Inventors: Yoshitaka Kadowaki, Tatsunori Toyota
  • Patent number: 9184338
    Abstract: The method of manufacturing a semiconductor device according to the present invention includes: a step of forming a semiconductor laminate on a growth substrate with a lift-off layer therebetween; a step of providing grooves in a grid pattern in the semiconductor laminate, thereby forming a plurality of semiconductor structures each having a nearly quadrangular transverse cross-sectional shape; a step of forming a conductive support body; and a step of removing the lift-off layer using a chemical lift-off process, in which step, in supplying an etchant to the grooves via through-holes provided in a portion above the grooves, the lift-off layer is etched from only one side surface of each semiconductor structure.
    Type: Grant
    Filed: September 28, 2011
    Date of Patent: November 10, 2015
    Assignees: BBSA LIMITED, DOW ELECTRONICS MATERIALS CO., LTD.
    Inventors: Meoung Whan Cho, Seog Woo Lee, Ryuichi Toba, Yoshitaka Kadowaki
  • Publication number: 20150295129
    Abstract: A luminescent device and a manufacturing method for the luminescent device and a semiconductor device which are free from occurrence of cracks in a compound semiconductor layer due to the internal stress in the compound semiconductor layer at the time of chemical lift-off. The luminescent device manufacturing method includes forming a device region on part of an epitaxial substrate through a lift-off layer; forming a sacrificing portion, being not removed in a chemical lift-off step, around device region on epitaxial substrate; covering epitaxial substrate and semiconductor layer and forming a covering layer such that level of surface thereof in the region away from device region is lower than luminescent layer surface; removing covering layer on semiconductor layer, and that on sacrificing portion surface; forming a reflection layer on covering layer surface and semiconductor layer surface; and forming a supporting substrate by providing plating on reflection layer.
    Type: Application
    Filed: May 29, 2015
    Publication date: October 15, 2015
    Applicant: DOWA ELECTRONICS MATERIALS CO., LTD.
    Inventors: Yoshitaka KADOWAKI, Tatsunori TOYOTA
  • Publication number: 20150263234
    Abstract: Provided is a high quality III nitride semiconductor device in which, not only X-shaped cracks extending from the vicinity of the corners of semiconductor structures to the center portion thereof, but also crack spots at the center portion can be prevented from being formed and can provide a method of efficiently manufacturing the III nitride semiconductor device. The III nitride semiconductor device of the present invention includes a support and two semiconductor structures having a nearly quadrangular transverse cross-sectional shape that are provided on the support. The two semiconductor structures are situated such that one side surface of one of the two semiconductor structures is placed to face one side surface of the other of them. The support covers the other three side surfaces and of the four sides of the semiconductor structures.
    Type: Application
    Filed: September 28, 2012
    Publication date: September 17, 2015
    Inventors: Meoung Whan Cho, Seog Woo Lee, Ryuichi Toba, Yoshitaka Kadowaki
  • Publication number: 20150228845
    Abstract: A III nitride semiconductor light emitting device achieves improved light output power while reducing forward voltage. A III nitride semiconductor light emitting device according to the present invention includes, in the following order, a p-side electrode, a p-type III nitride semiconductor layer, a light emitting layer, an n-type III nitride semiconductor layer, and a buffer layer including an undoped III nitride semiconductor layer. An exposed portion is provided on the buffer layer. An n-side electrode is provided continuously on the n-type III nitride semiconductor layer, exposed in the exposed portion, and the buffer layer. The n-side electrode includes a plurality of contact portions in contact with the n-type III nitride semiconductor layer, and the contact portions are electrically interconnected on the buffer layer.
    Type: Application
    Filed: August 30, 2013
    Publication date: August 13, 2015
    Inventors: Yoshitaka Kadowaki, Tatsunori Toyota
  • Patent number: 9082893
    Abstract: A luminescent device and a manufacturing method for the luminescent device and a semiconductor device which are free from occurrence of cracks in a compound semiconductor layer due to the internal stress in the compound semiconductor layer at the time of chemical lift-off. The luminescent device manufacturing method includes forming a device region on part of an epitaxial substrate through a lift-off layer; forming a sacrificing portion, being not removed in a chemical lift-off step, around device region on epitaxial substrate; covering epitaxial substrate and semiconductor layer and forming a covering layer such that level of surface thereof in the region away from device region is lower than luminescent layer surface; removing covering layer on semiconductor layer, and that on sacrificing portion surface; forming a reflection layer on covering layer surface and semiconductor layer surface; and forming a supporting substrate by providing plating on reflection layer.
    Type: Grant
    Filed: January 11, 2012
    Date of Patent: July 14, 2015
    Assignee: DOW A ELECTRONICS MATERIALS CO., LTD.
    Inventors: Yoshitaka Kadowaki, Tatsunori Toyota
  • Publication number: 20150187887
    Abstract: Provided is a III nitride semiconductor device higher heat dissipation performance, and a method of manufacturing a III nitride semiconductor device which makes it possible to fabricate such a III nitride semiconductor device at higher yield. In a method of a III nitride semiconductor device, a semiconductor structure obtained by sequentially stacking an n-layer, an active layer, and a p-layer is formed on a growth substrate; a support body including a first support electrically connected to an n-layer to serve as an n-side electrode, a second support electrically connected to a p-layer to serve as a p-side electrode, and structures made of an insulator for insulation between first and second supports is formed on the p-layer side of the semiconductor structure; and the growth substrate is separated using a lift-off process. The first support and the second support are grown by plating.
    Type: Application
    Filed: July 4, 2012
    Publication date: July 2, 2015
    Applicants: DOWA ELECTRONICS MATERIALS CO., LTD., BBSA LIMITED
    Inventors: Meoung Whan Cho, Seog Woo Lee, Pil Guk Jang, Hoe Young Yang, Jin Hee Kim, Ho Kyun Rho, Se Young Moon, Ryuichi Toba, Yoshitaka Kadowaki
  • Patent number: 9012935
    Abstract: A method for manufacturing vertically structured Group III nitride semiconductor LED chips includes a step of forming a light emitting laminate on a growth substrate; a step of forming a plurality of separate light emitting structures by partially removing the light emitting laminate to partially expose the growth substrate; a step of forming a conductive support on the plurality of light emitting structures; a step of lifting off the growth substrate from the plurality of light emitting structures; and a step of cutting the conductive support thereby singulating a plurality of LED chips each having the light emitting structure. The step of partially removing the light emitting laminate is performed such that each of the plurality of light emitting structures has a top view shape of a circle or a 4n-gon (ā€œnā€ is a positive integer) having rounded corners.
    Type: Grant
    Filed: September 4, 2013
    Date of Patent: April 21, 2015
    Assignees: Wavesquare Inc., Dowa Electronics Materials Co., Ltd.
    Inventors: Meoung Whan Cho, Seog Woo Lee, Pil Guk Jang, Ryuichi Toba, Tatsunori Toyota, Yoshitaka Kadowaki