Patents by Inventor Toru Oka

Toru Oka 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: 11934305
    Abstract: According to an embodiment, when receiving a read request designating a logical address range of a particular size or more from a host, a first circuit issues a plurality of first sub-commands, each of which is a sub-command for each first data unit, in order of logical addresses. A second circuit respectively adds serial numbers corresponding to the plurality of first sub-commands in the order of issuance. A plurality of third circuits respectively executes processing of specifying locations of the first data unit based on management information for the plurality of first sub-commands in a distributed manner. A fifth circuit reorders the plurality of first sub-commands in the logical address order based on the serial numbers after the processing by the plurality of third circuits. A sixth circuit executes a read operation on a first memory based on the plurality of first sub-commands reordered in the order of logical addresses.
    Type: Grant
    Filed: June 15, 2022
    Date of Patent: March 19, 2024
    Assignee: Kioxia Corporation
    Inventors: Toru Motoya, Mitsunori Tadokoro, Tomonori Yokoyama, Fuyuki Ichiba, Kensuke Minato, Kimihisa Oka
  • Publication number: 20210376082
    Abstract: The present invention provides a semiconductor device in which the contact resistance of the body electrode is reduced without reducing the channel mobility. The p-type layer is a Mg-doped p-GaN layer deposited on the first re-type layer. The p-type layer has a two-layer structure in which a first p-type layer and a second p-type layer are sequentially deposited. The second p-type layer has a Mg concentration higher than the Mg concentration of the first p-type layer. The recess is formed in a predetermined position on the surface of the second n-type layer, and has a depth passing through the second n-type layer and reaching the second p-type layer. The body electrode is formed on the bottom surface of the recess in contact with the p-type layer exposed thereon.
    Type: Application
    Filed: April 29, 2021
    Publication date: December 2, 2021
    Inventors: Toru OKA, Tsutomu INA
  • Publication number: 20210376127
    Abstract: The present invention provides a method for producing a semiconductor device in which the on-resistance can be reduced while increasing the threshold voltage. A first n-type layer, a first p-type layer, a second p-type layer, and a second n-type layer are sequentially deposited through MOCVD on a substrate. The second p-type layer has a Mg concentration higher than the Mg concentration of the first p-type layer and not less than 6×1018/cm3. By setting the Mg concentration in this way, the threshold voltage is almost determined by the Mg concentration of the second p-type layer, and the threshold voltage does not depend on the Mg concentration of the first p-type layer. Therefore, channel resistance, that is, on-resistance is reduced by setting the Mg concentration of the first p-type layer to less than 6×1018/cm3.
    Type: Application
    Filed: April 27, 2021
    Publication date: December 2, 2021
    Inventors: Toru OKA, Yukihisa UENO
  • Patent number: 11069788
    Abstract: To provide a semiconductor device including an electrode having a low contact resistance with the back surface of a GaN substrate and being suitably bonded with solder, and having a low electric resistance of the current flowing in a vertical direction. The semiconductor device has a GaN substrate, a first semiconductor layer, a second semiconductor layer, a third semiconductor layer, a fourth semiconductor layer, a body electrode, a drain electrode, a source electrode, and a gate electrode. The drain electrode has a Ti layer, an Al layer, a Ti layer, a TiN layer, a Ti layer, a Ni layer, and an Ag layer sequentially from the second surface of the GaN substrate.
    Type: Grant
    Filed: February 26, 2020
    Date of Patent: July 20, 2021
    Assignee: TOYODA GOSEI CO., LTD.
    Inventors: Noriaki Murakami, Toru Oka
  • Patent number: 11011607
    Abstract: The likelihood of formation of a corner resulting from a recess in a part of an n-type semiconductor layer is reduced at a deeper position than a p-type semiconductor layer. A method of manufacturing a semiconductor device comprises: forming a gallium nitride (GaN) based n-type semiconductor layer containing n-type impurities; forming a groove by forming a first mask on a part of a surface of the n-type semiconductor layer and then etching a part uncovered by the first mask; removing the first mask; forming a gallium nitride (GaN) based p-type semiconductor layer containing p-type impurities on the surface of the n-type semiconductor layer including the groove; etching the p-type semiconductor layer so as to expose the n-type semiconductor layer at least in a range differing from a range in the presence of the groove; and forming a metal electrode contacting the exposed n-type semiconductor layer and the p-type semiconductor layer.
    Type: Grant
    Filed: September 17, 2019
    Date of Patent: May 18, 2021
    Assignee: TOYODA GOSEI CO., LTD.
    Inventors: Kota Yasunishi, Toru Oka, Kazuya Hasegawa
  • Patent number: 10854454
    Abstract: To restrain a side portion of a trench from being damaged by ion implantation. A method for manufacturing a semiconductor device comprises a stacking process, an ion implantation process, a heat treatment process, a groove forming process, and a first electrode forming process. In the stacking process, a p-type semiconductor layer is stacked on a first n-type semiconductor layer. In the ion implantation process, an n-type impurity or a p-type impurity is ion-implanted into a position on a surface of the p-type semiconductor layer. The position is away from a position where a groove is to be formed. In the heat treatment process, heat treatment is performed to activate the ion-implanted impurity so as to form an implanted region and to diffuse a p-type impurity in the p-type semiconductor layer into the first n-type semiconductor layer located below the implanted region so as to form a p-type impurity diffused region.
    Type: Grant
    Filed: April 22, 2019
    Date of Patent: December 1, 2020
    Assignee: TOYODA GOSEI CO., LTD.
    Inventors: Yukihisa Ueno, Nariaki Tanaka, Junya Nishii, Toru Oka
  • Patent number: 10832911
    Abstract: An n-type GaN layer, a p-type diffusion region formed by ion implantation and annealing in a part of the n-type layer, and a Schottky electrode are formed on the n-type layer. A region without the p-type region is defined as region A, and a region with the p-type region is defined as region B. In region A, an average density of each electron trap level of the n-type layer in a region having a depth of 0.8 ?m to 1.6 ?m on the n-type layer side is set so as to satisfy the predetermined conditions. In region B, an average density of each carrier trap level of the n-type layer in a region having a depth of 0.8 ?m to 1.6 ?m on the n-type layer side from a boundary between the n-type layer and the p-type diffusion region is set so as to satisfy the predetermined conditions.
    Type: Grant
    Filed: August 29, 2019
    Date of Patent: November 10, 2020
    Assignee: TOYODA GOSEI CO., LTD.
    Inventors: Nariaki Tanaka, Toru Oka, Yukihisa Ueno, Kota Yasunishi
  • Patent number: 10777674
    Abstract: To suppress breakage of a diode. A semiconductor device comprises a stacked body and a first electrode. The stacked body includes a first nitride semiconductor layer, a second nitride semiconductor layer, a third nitride semiconductor layer, and a fourth nitride semiconductor layer that are stacked in sequence. The first electrode is in contact with a surface of the first nitride semiconductor layer that is opposite to a surface in contact with the second nitride semiconductor layer. The semiconductor device includes a transistor forming region and a diode forming region adjacent to the transistor forming region. The transistor forming region includes a first groove, a second electrode, and a third electrode. The first groove has a bottom portion located in the second nitride semiconductor layer. The second electrode is formed on a surface of the first groove.
    Type: Grant
    Filed: March 13, 2019
    Date of Patent: September 15, 2020
    Assignee: TOYODA GOSEI CO., LTD.
    Inventors: Takaki Niwa, Toru Oka
  • Publication number: 20200287012
    Abstract: To provide a semiconductor device including an electrode having a low contact resistance with the back surface of a GaN substrate and being suitably bonded with solder, and having a low electric resistance of the current flowing in a vertical direction. The semiconductor device has a GaN substrate, a first semiconductor layer, a second semiconductor layer, a third semiconductor layer, a fourth semiconductor layer, a body electrode, a drain electrode, a source electrode, and a gate electrode. The drain electrode has a Ti layer, an Al layer, a Ti layer, a TiN layer, a Ti layer, a Ni layer, and an Ag layer sequentially from the second surface of the GaN substrate.
    Type: Application
    Filed: February 26, 2020
    Publication date: September 10, 2020
    Inventors: Noriaki MURAKAMI, Toru Oka
  • Publication number: 20200098872
    Abstract: The likelihood of formation of a corner resulting from a recess in a part of an n-type semiconductor layer is reduced at a deeper position than a p-type semiconductor layer. A method of manufacturing a semiconductor device comprises: forming a gallium nitride (GaN) based n-type semiconductor layer containing n-type impurities; forming a groove by forming a first mask on a part of a surface of the n-type semiconductor layer and then etching a part uncovered by the first mask; removing the first mask; forming a gallium nitride (GaN) based p-type semiconductor layer containing p-type impurities on the surface of the n-type semiconductor layer including the groove; etching the p-type semiconductor layer so as to expose the n-type semiconductor layer at least in a range differing from a range in the presence of the groove; and forming a metal electrode contacting the exposed n-type semiconductor layer and the p-type semiconductor layer.
    Type: Application
    Filed: September 17, 2019
    Publication date: March 26, 2020
    Inventors: Kota YASUNISHI, Toru Oka, Kazuya Hasegawa
  • Publication number: 20200098565
    Abstract: An n-type GaN layer, a p-type diffusion region formed by ion implantation and annealing in a part of the n-type layer, and a Schottky electrode are formed on the n-type layer. A region without the p-type region is defined as region A, and a region with the p-type region is defined as region B. In region A, an average density of each electron trap level of the n-type layer in a region having a depth of 0.8 ?m to 1.6 ?m on the n-type layer side is set so as to satisfy the predetermined conditions. In region B, an average density of each carrier trap level of the n-type layer in a region having a depth of 0.8 ?m to 1.6 ?m on the n-type layer side from a boundary between the n-type layer and the p-type diffusion region is set so as to satisfy the predetermined conditions.
    Type: Application
    Filed: August 29, 2019
    Publication date: March 26, 2020
    Inventors: Nariaki Tanaka, Toru Oka, Yukihisa Ueno, Kota Yasunishi
  • Publication number: 20200054776
    Abstract: It is an object of the present invention to provide a photocatalyst-carrying mesh sheet which firmly supports anatase type titanium oxide as a photocatalyst to prevent peeling, and increases opportunities for contact with the photocatalyst to significantly improve a purification treatment efficiency provided by the photocatalyst and to suppress manufacturing cost. A photocatalyst-carrying mesh sheet (S1) is disclosed, which includes: a net-form titanium sheet (11) having a periodic pattern; a titanium oxide film (3) formed on a surface of the net-form titanium sheet (11); and an anatase type titanium oxide particle (4) supported on the titanium oxide film (3).
    Type: Application
    Filed: February 9, 2018
    Publication date: February 20, 2020
    Inventors: Yoshiki KIMURA, Katsuhiro YAMAGUCHI, Toru OKA, Yuko MORITO
  • Publication number: 20190341260
    Abstract: To restrain a side portion of a trench from being damaged by ion implantation. A method for manufacturing a semiconductor device comprises a stacking process, an ion implantation process, a heat treatment process, a groove forming process, and a first electrode forming process. In the stacking process, a p-type semiconductor layer is stacked on a first n-type semiconductor layer. In the ion implantation process, an n-type impurity or a p-type impurity is ion-implanted into a position on a surface of the p-type semiconductor layer. The position is away from a position where a groove is to be formed. In the heat treatment process, heat treatment is performed to activate the ion-implanted impurity so as to form an implanted region and to diffuse a p-type impurity in the p-type semiconductor layer into the first n-type semiconductor layer located below the implanted region so as to form a p-type impurity diffused region.
    Type: Application
    Filed: April 22, 2019
    Publication date: November 7, 2019
    Inventors: Yukihisa UENO, Nariaki TANAKA, Junya NISHII, Toru OKA
  • Publication number: 20190305126
    Abstract: To suppress breakage of a diode. A semiconductor device comprises a stacked body and a first electrode. The stacked body includes a first nitride semiconductor layer, a second nitride semiconductor layer, a third nitride semiconductor layer, and a fourth nitride semiconductor layer that are stacked in sequence. The first electrode is in contact with a surface of the first nitride semiconductor layer that is opposite to a surface in contact with the second nitride semiconductor layer. The semiconductor device includes a transistor forming region and a diode forming region adjacent to the transistor forming region. The transistor forming region includes a first groove, a second electrode, and a third electrode. The first groove has a bottom portion located in the second nitride semiconductor layer. The second electrode is formed on a surface of the first groove.
    Type: Application
    Filed: March 13, 2019
    Publication date: October 3, 2019
    Inventors: Takaki NIWA, Toru OKA
  • Patent number: 10074728
    Abstract: A semiconductor device comprises: a gate insulating film 190 stacked on a semiconductor layer 130; and a gate electrode layer 230 stacked on the gate insulating film 190 and provided to apply a voltage via the gate insulating film 190 for formation of a channel in the semiconductor layer 130. The gate insulating film 190 includes: a first insulation film 192 stacked on the semiconductor layer 130; and a second insulation film 194 between the first insulation film 192 and the gate electrode layer 230. When ?1 and ?2 respectively represent relative permittivities of the first and second insulation film 192, 194, d1 [nm] and d2 [nm] represent film thicknesses of the first and second insulation film 192, 194, and Vmax [V] represents a rated voltage applicable to the gate electrode layer 230, the semiconductor device is configured to satisfy ?1<?2 and meet (C1): V ? max d ? ? 1 + ? ? ? 1 ? ? ? 2 · d ? ? 2 ? 21 ? [ MV ? / ? cm ] .
    Type: Grant
    Filed: September 30, 2016
    Date of Patent: September 11, 2018
    Assignee: TOYODA GOSEI CO., LTD.
    Inventors: Toru Oka, Takahiro Sonoyama
  • Patent number: 9620608
    Abstract: An object is to use an electrode made of a less expensive material than gold (Au). A semiconductor device comprises: a first titanium layer that is formed to cover at least part of a semiconductor layer and is made of titanium; an aluminum layer that is formed on the first titanium layer on opposite side of the semiconductor layer and mainly consists of aluminum; a titanium nitride layer that is formed on the aluminum layer on opposite side of the first titanium layer and is made of titanium nitride; and an electrode layer that is formed on the titanium nitride layer on opposite side of the aluminum layer and is made of copper.
    Type: Grant
    Filed: May 16, 2014
    Date of Patent: April 11, 2017
    Assignee: TOYODA GOSEI CO., LTD.
    Inventors: Noriaki Murakami, Toru Oka
  • Publication number: 20170025515
    Abstract: A semiconductor device comprises: a gate insulating film 190 stacked on a semiconductor layer 130; and a gate electrode layer 230 stacked on the gate insulating film 190 and provided to apply a voltage via the gate insulating film 190 for formation of a channel in the semiconductor layer 130. The gate insulating film 190 includes: a first insulation film 192 stacked on the semiconductor layer 130; and a second insulation film 194 between the first insulation film 192 and the gate electrode layer 230. When ?1 and ?2 respectively represent relative permittivities of the first and second insulation film 192, 194, d1 [nm] and d2 [nm] represent film thicknesses of the first and second insulation film 192, 194, and Vmax [V] represents a rated voltage applicable to the gate electrode layer 230, the semiconductor device is configured to satisfy ?1<?2 and meet (C1): V ? max d ? ? 1 + ? ? ? 1 ? ? ? 2 · d ? ? 2 ? 21 ? [ MV ? / ? cm ] .
    Type: Application
    Filed: September 30, 2016
    Publication date: January 26, 2017
    Inventors: Toru OKA, Takahiro SONOYAMA
  • Patent number: 9508822
    Abstract: A semiconductor device comprises: a gate insulating film 190 stacked on a semiconductor layer 130; and a gate electrode layer 230 stacked on the gate insulating film 190 and provided to apply a voltage via the gate insulating film 190 for formation of a channel in the semiconductor layer 130. The gate insulating film 190 includes: a first insulation film 192 stacked on the semiconductor layer 130; and a second insulation film 194 between the first insulation film 192 and the gate electrode layer 230. When ?1 and ?2 respectively represent relative permittivities of the first and second insulation film 192, 194, d1 [nm] and d2 [nm] represent film thicknesses of the first and second insulation film 192, 194, and Vmax [V] represents a rated voltage applicable to the gate electrode layer 230, the semiconductor device is configured to satisfy ?1<?2 and meet (C1): V ? ? max d ? ? 1 + ? ? ? 1 ? ? ? 2 · d ? ? 2 ? 21 ? [ M ? ? V ? / ? cm ] ? .
    Type: Grant
    Filed: March 11, 2014
    Date of Patent: November 29, 2016
    Assignee: Toyoda Gosei Co., Ltd.
    Inventors: Toru Oka, Takahiro Sonoyama
  • Patent number: 9443950
    Abstract: A semiconductor device includes: a p-type semiconductor layer; an n-type semiconductor layer connected with the p-type semiconductor layer; a first electrode layer formed on the n-type semiconductor layer; and a second electrode layer formed on the p-type semiconductor layer. The first electrode layer and the second electrode layer are electrically connected such as to each operate at an identical potential. The second electrode layer is connected with at least a part of a surface of the first electrode layer which is opposite to a surface of the first electrode layer that is in contact with the n-type semiconductor layer.
    Type: Grant
    Filed: December 12, 2013
    Date of Patent: September 13, 2016
    Assignee: TOYODA GOSEI CO., LTD.
    Inventors: Toru Oka, Nariaki Tanaka
  • Patent number: 9437525
    Abstract: An object is to use an electrode made of a less expensive material than gold (Au). A semiconductor device comprises: a first titanium layer that is formed to cover at least part of a semiconductor layer and is made of titanium; an aluminum layer that is formed on the first titanium layer on opposite side of the semiconductor layer and mainly consists of aluminum; a titanium nitride layer that is formed on the aluminum layer on opposite side of the first titanium layer and is made of titanium nitride; and an electrode layer that is formed on the titanium nitride layer on opposite side of the aluminum layer and is made of silver.
    Type: Grant
    Filed: April 28, 2014
    Date of Patent: September 6, 2016
    Assignee: TOYODA GOSEI CO., LTD.
    Inventors: Noriaki Murakami, Toru Oka