Patents by Inventor Tatsunori Toyota

Tatsunori Toyota 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: 10475964
    Abstract: Provided is a method of producing an n-type ohmic electrode that can form a good ohmic contact with an n-type AlxGa1-xN (0.5?x?1) layer. The method of producing an n-type ohmic electrode includes: a first step of forming a first layer 11 made of one of Ti and Hf on a surface of a layer 30; a second step of forming a second layer 12 made of Sn on the surface of the first layer 11; a third step of forming a third layer 13 made of one of V and Mo on the surface of the second layer 12; a fourth step of forming a fourth layer 14 made of Al on the surface of the third layer 13; and a fifth step of performing heat treatment on the first layer 11, the second layer 12, the third layer 13, and the fourth layer 14.
    Type: Grant
    Filed: September 2, 2016
    Date of Patent: November 12, 2019
    Assignee: DOWA Electronics Materials Co., Ltd.
    Inventor: Tatsunori Toyota
  • Publication number: 20180248080
    Abstract: Provided is a method of producing an n-type ohmic electrode that can form a good ohmic contact with an n-type AlxGa1?xN (0.5?x?1) layer. The method of producing an n-type ohmic electrode includes: a first step of forming a first layer 11 made of one of Ti and Hf on a surface of a layer 30; a second step of forming a second layer 12 made of Sn on the surface of the first layer 11; a third step of forming a third layer 13 made of one of V and Mo on the surface of the second layer 12; a fourth step of forming a fourth layer 14 made of Al on the surface of the third layer 13; and a fifth step of performing heat treatment on the first layer 11, the second layer 12, the third layer 13, and the fourth layer 14.
    Type: Application
    Filed: September 2, 2016
    Publication date: August 30, 2018
    Applicant: DOWA Electronics Materials Co., Ltd.
    Inventor: Tatsunori TOYOTA
  • 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: 9263642
    Abstract: A III nitride semiconductor light emitting device with improved light emission efficiency achieved without significantly increasing forward voltage by achieving both good ohmic contact between an electrode and a semiconductor layer, and sufficient functionality of a reflective electrode layer, and a method for manufacturing the same. The III nitride semiconductor light emitting device has a III nitride semiconductor laminate including an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer; an n-side electrode, a p-side electrode; and a composite layer having a reflective electrode portion and a contact portion made of AlxGa1-xN (0?x?0.05) on a second surface of the III nitride semiconductor laminate. The second surface is opposite to a first surface on the light extraction side.
    Type: Grant
    Filed: September 30, 2011
    Date of Patent: February 16, 2016
    Assignee: DOWA ELECTRONICS MATERIALS CO., LTD.
    Inventors: Tatsunori Toyota, Tomohiko Shibata
  • 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: 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
  • 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 (“n” 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
  • Publication number: 20150069583
    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: Application
    Filed: December 12, 2012
    Publication date: March 12, 2015
    Inventors: Yoshitaka Kadowaki, Tatsunori Toyota
  • Patent number: 8962362
    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 (“n” is a positive integer) having rounded corners.
    Type: Grant
    Filed: November 5, 2009
    Date of Patent: February 24, 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
  • Publication number: 20140327034
    Abstract: A semiconductor light emitting device of the present invention includes a semiconductor laminate including a first conductivity type semiconductor layer, a light emitting layer, and a second conductivity-type semiconductor layer in his order; a contact portion including a stack including a contact layer and an ohmic electrode layer on the first conductivity type semiconductor layer; a first electrode which is in contact with the ohmic electrode layer and is electrically connected to the first conductivity-type semiconductor layer; a second electrode electrically connected to the second conductivity type semiconductor layer. The contact portion has a plurality of island-like openings in which the first conductivity-type semiconductor layer is exposed.
    Type: Application
    Filed: November 6, 2012
    Publication date: November 6, 2014
    Inventor: Tatsunori Toyota
  • Patent number: 8878189
    Abstract: An object of the present invention is to provide a Group III nitride semiconductor epitaxial substrate, a Group III nitride semiconductor element, and a Group III nitride semiconductor free-standing substrate, which have good crystallinity, with not only AlGaN, GaN, and GaInN the growth temperature of which is 1050° C. or less, but also with AlxGa1-xN having a high Al composition, the growth temperature of which is high; a Group III nitride semiconductor growth substrate used for producing these, and a method for efficiently producing those. The present invention provides a Group III nitride semiconductor growth substrate comprising a crystal growth substrate including a surface portion composed of a Group III nitride semiconductor which contains at least Al, and a scandium nitride film formed on the surface portion are provided.
    Type: Grant
    Filed: March 25, 2010
    Date of Patent: November 4, 2014
    Assignees: Dowa Holdings Co., Ltd., Dowa Electronics Materials Co., Ltd.
    Inventors: Ryuichi Toba, Masahito Miyashita, Tatsunori Toyota, Yoshitaka Kadowaki
  • Patent number: 8860294
    Abstract: To provide a light emitting element, having: a lamination structure including a first conductive layer and a second conductive layer with a light emitting layer interposed between them; a groove structure in which the second conductive layer and the light emitting layer are divided into large and small two parts; a second conductive electrode pad that is electrically connected to the second conductive layer on the divided larger second conductive layer, a first conductive electrode pad on the divided smaller second conductive layer, and two or more electrical contacts connected to the first conductive layer so as to be independent from each other, by a conductive wiring extending to the first conductive layer, with the first conductive electrode pad as a start point.
    Type: Grant
    Filed: December 8, 2010
    Date of Patent: October 14, 2014
    Assignee: Dowa Electronics Materials Co., Ltd.
    Inventors: Tatsunori Toyota, Yutaka Ohta
  • Patent number: 8765584
    Abstract: A semiconductor device and a manufacturing method therefor, wherein, during lift-off, no cracks due to internal stresses occur in the compound semiconductor layer. A method for manufacturing a semiconductor device having a structure in which a semiconductor layer is bonded on a supporting substrate, including: a device region formation step of forming a device region including the semiconductor layer on a growth substrate through a lift-off layer; a columnar member formation step of forming a columnar member on the growth substrate; a bonding step of bonding the tops of the semiconductor layer and the columnar member to a supporting substrate; a lift-off step of separating the bottom face of the semiconductor layer from the growth substrate by removing the lift-off layer, and not separating the columnar member from the growth substrate; and a step of separating the columnar member from the supporting substrate.
    Type: Grant
    Filed: July 26, 2011
    Date of Patent: July 1, 2014
    Assignee: Dowa Electronics Materials Co., Ltd.
    Inventors: Yoshitaka Kadowaki, Tatsunori Toyota
  • Patent number: 8736025
    Abstract: An object of the present invention is to address the problems described herein and to provide a III-nitride semiconductor epitaxial substrate, a III-nitride semiconductor element, and a III-nitride semiconductor freestanding substrate, which have good crystallinity, not only with AlGaN, GaN, or GaInN, the growth temperature of which is at or below 1050° C., but also with AlxGa1-xN, the growth temperature of which is high and which has a high Al composition, as well as a III-nitride semiconductor growth substrate for fabricating these and a method for efficiently fabricating these. The invention is characterized by being equipped with: a crystal growth substrate, at least the surface portion of which substrate includes a III-nitride semiconductor containing Al; and a single metallic layer formed on the surface portion, the single metallic layer being made from Zr or Hf.
    Type: Grant
    Filed: December 25, 2009
    Date of Patent: May 27, 2014
    Assignees: Dowa Electroncs Materials Co., Ltd., Dowa Holdings Co., Ltd.
    Inventors: Ryuichi Toba, Masahito Miyashita, Tatsunori Toyota
  • Publication number: 20140001511
    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 (“n” is a positive integer) having rounded corners.
    Type: Application
    Filed: September 4, 2013
    Publication date: January 2, 2014
    Applicants: DOWA ELECTRONICS MATERIALS CO., LTD., WAVESQUARE INC.
    Inventors: Meoung Whan CHO, Seog Woo LEE, Pil Guk JANG, Ryuichi TOBA, Tatsunori TOYOTA, Yoshitaka KADOWAKI
  • Publication number: 20130285074
    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: January 11, 2012
    Publication date: October 31, 2013
    Applicant: DOWA ELECTRONICS MATERIALS CO., LTD.
    Inventors: Yoshitaka Kakowaki, Tatsunori Toyota
  • Publication number: 20130193471
    Abstract: A III nitride semiconductor light emitting device with improved light emission efficiency achieved without significantly increasing forward voltage by achieving both good ohmic contact between an electrode and a semiconductor layer, and sufficient functionality of a reflective electrode layer, and a method for manufacturing the same. The III nitride semiconductor light emitting device has a III nitride semiconductor laminate including an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer; an n-side electrode, a p-side electrode; and a composite layer having a reflective electrode portion and a contact portion made of AlxGa1-xN (0?x?0.05) on a second surface of the III nitride semiconductor laminate. The second surface is opposite to a first surface on the light extraction side.
    Type: Application
    Filed: September 30, 2011
    Publication date: August 1, 2013
    Applicant: DOWA ELECTRONICS MATERIALS CO., LTD.
    Inventors: Tatsunori Toyota, Tomohiko Shibata
  • Publication number: 20120299465
    Abstract: To provide a light emitting element, having: a lamination structure including a first conductive layer and a second conductive layer with a light emitting layer interposed between them; a groove structure in which the second conductive layer and the light emitting layer are divided into large and small two parts; a second conductive electrode pad that is electrically connected to the second conductive layer on the divided larger second conductive layer, a first conductive electrode pad on the divided smaller second conductive layer, and two or more electrical contacts connected to the first conductive layer so as to be independent from each other, by a conductive wiring extending to the first conductive layer, with the first conductive electrode pad as a start point.
    Type: Application
    Filed: December 8, 2010
    Publication date: November 29, 2012
    Applicant: DOWA ELECTRONICS MATERIALS CO., LTD.
    Inventors: Tatsunori Toyota, Yutaka Ohta