Patents by Inventor Tadaaki Oikawa

Tadaaki Oikawa 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: 11832528
    Abstract: A magnetic memory device includes a substrate; a first magnetoresistive effect element; and a second magnetoresistive effect element provided at a side of the first magnetoresistive effect element opposite to a side of the first magnetoresistive effect element at which the substrate is provided. A heat absorption rate of the first magnetoresistive effect element is lower than a heat absorption rate of the second magnetoresistive effect element.
    Type: Grant
    Filed: April 11, 2022
    Date of Patent: November 28, 2023
    Assignee: Kioxia Corporation
    Inventors: Kazuya Sawada, Young Min Eeh, Eiji Kitagawa, Taiga Isoda, Tadaaki Oikawa, Kenichi Yoshino
  • Publication number: 20230269950
    Abstract: A magnetic memory device according to an embodiment includes a first ferromagnetic layer, a first nonmagnetic layer on the first ferromagnetic layer, a second ferromagnetic layer on the first nonmagnetic layer, an oxide layer on the second ferromagnetic layer, and a second nonmagnetic layer on the oxide layer. The oxide layer contains an oxide of a rare-earth element. The second nonmagnetic layer contains cobalt (Co), iron (Fe), boron (B), and molybdenum (Mo).
    Type: Application
    Filed: June 16, 2022
    Publication date: August 24, 2023
    Applicant: Kioxia Corporation
    Inventors: Tadaaki OIKAWA, Kenichi YOSHINO, Kazuya SAWADA, Takuya SHIMANO, Young Min EEH, Taiga ISODA
  • Publication number: 20230072970
    Abstract: A magnetoresistance memory device includes first, second, third and fourth ferromagnetic layers; a first and second ferromagnetic oxide layers; a metal layer; an insulating layer. The second ferromagnetic layer includes one of iron and cobalt included in the first ferromagnetic oxide layer and one element of a first element group. The second ferromagnetic oxide layer includes an oxide of an alloy of the one of iron and cobalt included in the second ferromagnetic oxide layer with a first element, which has a standard electrode potential lower than that of iron or cobalt and that of the one element of the first element group included in the second ferromagnetic layer.
    Type: Application
    Filed: December 13, 2021
    Publication date: March 9, 2023
    Applicant: Kioxia Corporation
    Inventors: Taiga ISODA, Eiji KITAGAWA, Young Min EEH, Tadaaki OIKAWA, Kazuya SAWADA
  • Publication number: 20230062011
    Abstract: According to one embodiment, a magnetic memory device includes a first magnetic layer having a variable magnetisation direction, a second magnetic layer having a fixed magnetization direction, a nonmagnetic layer provided between the first magnetic layer and the second magnetic layer, a third magnetic layer provided on a lower side of the first magnetic layer, the second magnetic layer and the nonmagnetic layer, having a fixed magnetization direction antiparallel to the magnetization direction of the second magnetic layer, and formed of an alloy of cobalt (Co) and platinum (Pt), and a buffer layer provided on a lower side of the third magnetic layer and including a first layer portion containing rhenium (Re),
    Type: Application
    Filed: December 9, 2021
    Publication date: March 2, 2023
    Applicant: Kioxia Corporation
    Inventors: Tadaaki OIKAWA, Youngmin EEH, Eiji KITAGAWA, Taiga ISODA
  • Publication number: 20230026414
    Abstract: According to one embodiment, a magnetoresistive memory device includes: a first ferromagnetic layer; a stoichiometric first layer; a first insulator between the first ferromagnetic layer and the first layer; a second ferromagnetic layer between the first insulator and the first layer; and a non-stoichiometric second layer between the second ferromagnetic layer and the first layer. The second layer is in contact with the second ferromagnetic layer and the first layer.
    Type: Application
    Filed: October 3, 2022
    Publication date: January 26, 2023
    Applicants: KIOXIA CORPORATION, SK HYNIX INC.
    Inventors: Taiga ISODA, Eiji KITAGAWA, Young Min Min EEH, Tadaaki OIKAWA, Kazuya SAWADA, Kenichi YOSHINO, Jong Koo LIM, Ku Youl JUNG, Guk Cheon Cheon KIM
  • Patent number: 11563168
    Abstract: A magnetic memory device includes a magnetoresistance effect element including a first, second, and third ferromagnetic layer, a first non-magnetic layer between the first and second ferromagnetic layer, and a second non-magnetic layer between the second and third ferromagnetic layer. The second ferromagnetic layer is between the first and third ferromagnetic layer. The third ferromagnetic layer includes a fourth ferromagnetic layer in contact with the second non-magnetic layer, a third non-magnetic layer, and a fourth non-magnetic layer between the fourth ferromagnetic layer and the third non-magnetic layer. The first non-magnetic layer includes an oxide including magnesium (Mg). A melting point of the fourth non-magnetic layer is higher than the third non-magnetic layer.
    Type: Grant
    Filed: September 9, 2020
    Date of Patent: January 24, 2023
    Assignee: KIOXIA CORPORATION
    Inventors: Kazuya Sawada, Young Min Eeh, Tadaaki Oikawa, Eiji Kitagawa, Taiga Isoda
  • Patent number: 11495740
    Abstract: According to one embodiment, a magnetoresistive memory device includes: a first ferromagnetic layer; a stoichiometric first layer; a first insulator between the first ferromagnetic layer and the first layer; a second ferromagnetic layer between the first insulator and the first layer; and a non-stoichiometric second layer between the second ferromagnetic layer and the first layer. The second layer is in contact with the second ferromagnetic layer and the first layer.
    Type: Grant
    Filed: March 10, 2020
    Date of Patent: November 8, 2022
    Assignees: KIOXIA CORPORATION, SK HYNIX INC.
    Inventors: Taiga Isoda, Eiji Kitagawa, Young Min Eeh, Tadaaki Oikawa, Kazuya Sawada, Kenichi Yoshino, Jong Koo Lim, Ku Youl Jung, Guk Cheon Kim
  • Publication number: 20220302205
    Abstract: According to one embodiment, a magnetic memory device includes a stacked structure including a first magnetic layer having a fixed magnetization direction, a second magnetic layer having a variable magnetization direction, a non-magnetic layer provided between the first magnetic layer and the second magnetic layer, a molybdenum (Mo) layer provided on an opposite side of the non-magnetic layer with respect to the second magnetic layer, and an oxide layer provided between the second magnetic layer and the molybdenum (Mo) layer and containing a predetermined element selected from a rare earth element, silicon (Si) and aluminum (Al).
    Type: Application
    Filed: September 10, 2021
    Publication date: September 22, 2022
    Applicants: Kioxia Corporation, SK hynix Inc.
    Inventors: Tadaaki OIKAWA, Youngmin EEH, Eiji KITAGAWA, Taiga ISODA, Ku Youl JUNG, Jin Won JUNG
  • Publication number: 20220302372
    Abstract: According to one embodiment, a magnetic memory device includes a stacked structure including a first magnetic layer having a variable magnetization direction, a second magnetic layer having a fixed magnetization direction, a non-magnetic layer provided between the first magnetic layer and the second magnetic layer, and an oxide layer provided adjacent to the first magnetic layer, the first magnetic layer being provided between the non-magnetic layer and the oxide layer, and the oxide layer containing a rare earth element, boron (B), and oxygen (O).
    Type: Application
    Filed: September 10, 2021
    Publication date: September 22, 2022
    Applicants: Kioxia Corporation, SK hynix Inc.
    Inventors: Tadaaki OIKAWA, Youngmin EEH, Eiji KITAGAWA, Kazuya SAWADA, Taiga ISODA, Ku Youl JUNG, Jin Won JUNG
  • Patent number: 11404098
    Abstract: A memory device includes a first ferromagnetic layer, an insulating layer above the first ferromagnetic layer, a second ferromagnetic layer above the insulating layer, a capping layer on an upper surface of the second ferromagnetic layer, and an electrode on an upper surface of the capping layer. The second ferromagnetic layer includes iron atoms. The capping layer includes one or more elements identical to one or more elements in the second ferromagnetic layer. The electrode includes one or more elements identical to one or more of the elements in the capping layer and includes a material having a Vickers hardness higher than a Vickers hardness of an iron atom.
    Type: Grant
    Filed: September 9, 2020
    Date of Patent: August 2, 2022
    Assignees: KIOXIA CORPORATION, SK HYNIX INC.
    Inventors: Taiga Isoda, Eiji Kitagawa, Young Min Eeh, Tadaaki Oikawa, Kazuya Sawada, Jin Won Jung
  • Publication number: 20220238792
    Abstract: A magnetic memory device includes a substrate; a first magnetoresistive effect element; and a second magnetoresistive effect element provided at a side of the first magnetoresistive effect element opposite to a side of the first magnetoresistive effect element at which the substrate is provided. A heat absorption rate of the first magnetoresistive effect element is lower than a heat absorption rate of the second magnetoresistive effect element.
    Type: Application
    Filed: April 11, 2022
    Publication date: July 28, 2022
    Applicant: Kioxia Corporation
    Inventors: Kazuya SAWADA, Young Min EEH, Eiji KITAGAWA, Taiga ISODA, Tadaaki OIKAWA, Kenichi YOSHINO
  • Publication number: 20220199136
    Abstract: In general, according to one embodiment, a magnetoresistance memory device includes: a first ferromagnetic layer; an insulating layer above the first ferromagnetic layer; a second ferromagnetic layer above the insulating layer; a third ferromagnetic layer above the second ferromagnetic layer; and a fourth ferromagnetic layer above the third ferromagnetic layer. The third ferromagnetic layer includes an oxide of an alloy including iron. The fourth ferromagnetic layer includes iron and a 5d transition metal.
    Type: Application
    Filed: July 30, 2021
    Publication date: June 23, 2022
    Applicants: Kioxia Corporation, SK hynix Inc.
    Inventors: Taiga ISODA, Young Min EEH, Tadaaki OIKAWA, Eiji KITAGAWA, Kazuya SAWADA, Jin Won JUNG, Jung Hyeok KWAK
  • Patent number: 11329215
    Abstract: According to one embodiment, a magnetic memory device includes a substrate, a first layer stack, and a second layer stack at a same side of the first layer stack relative to the substrate, and farther than the first layer stack from the substrate. Each of the first and second layer stack includes a reference layer, a tunnel barrier layer provided in a direction relative to the reference layer, the direction being perpendicular to the substrate, a storage layer provided in the direction relative to the tunnel barrier layer, and a first nonmagnetic layer provided in the direction relative to the storage layer. A heat absorption rate of the first nonmagnetic layer of the first layer stack is lower than a heat absorption rate of the first nonmagnetic layer of the second layer stack.
    Type: Grant
    Filed: March 12, 2020
    Date of Patent: May 10, 2022
    Assignee: KIOXIA CORPORATION
    Inventors: Kazuya Sawada, Young Min Eeh, Eiji Kitagawa, Taiga Isoda, Tadaaki Oikawa, Kenichi Yoshino
  • Patent number: 11316095
    Abstract: According to one embodiment, a magnetic device includes a layer stack. The layer stack includes a first ferromagnetic layer, a second ferromagnetic layer, a first nonmagnetic layer between the first ferromagnetic layer and the second ferromagnetic layer, and a second nonmagnetic layer. The first ferromagnetic layer is interposed between the second nonmagnetic layer and the first nonmagnetic layer. The first nonmagnetic layer and the second nonmagnetic layer contain a magnesium oxide (MgO). The first ferromagnetic layer contains a higher amount of boron (B) at an interface with the first nonmagnetic layer than at an interface with the second nonmagnetic layer.
    Type: Grant
    Filed: March 12, 2020
    Date of Patent: April 26, 2022
    Assignee: KIOXIA CORPORATION
    Inventors: Tadaaki Oikawa, Young Min Eeh, Kenichi Yoshino, Eiji Kitagawa, Kazuya Sawada, Taiga Isoda
  • Publication number: 20220093848
    Abstract: According to one embodiment, a magnetic memory device includes a first magnetic layer, a second magnetic layer and a third magnetic layer having a fixed magnetization direction antiparallel to a magnetization direction of the second magnetic layer, first, second and third nonmagnetic layers. The firs nonmagnetic layer is between the first and second magnetic layers, the second magnetic layer is between the first nonmagnetic layer and the third magnetic layer, the third magnetic layer is between the second magnetic layer and the second nonmagnetic layer, the third nonmagnetic layer is between the second and the third magnetic layers, the third magnetic layer contains Co and Pt, and the second nonmagnetic layer contains at least one of Mo and W.
    Type: Application
    Filed: September 10, 2021
    Publication date: March 24, 2022
    Applicant: Kioxia Corporation
    Inventors: Eiji KITAGAWA, Youngmin EEH, Tadaaki OIKAWA, Kazuya SAWADA, Taiga ISODA
  • Publication number: 20220085279
    Abstract: According to one embodiment, a magnetic memory device includes a magnetoresistance effect element. The magnetoresistance effect element includes a first ferromagnetic layer, a second ferromagnetic layer, a third ferromagnetic layer, a first non-magnetic layer between the first ferromagnetic layer and the second ferromagnetic layer, and a second non-magnetic layer between the second ferromagnetic layer and the third ferromagnetic layer. The second ferromagnetic layer is between the first ferromagnetic layer and the third ferromagnetic layer. The first non-magnetic layer contains an oxide containing magnesium (Mg). The third ferromagnetic layer contains silicon (Si) or germanium (Ge).
    Type: Application
    Filed: September 10, 2021
    Publication date: March 17, 2022
    Applicant: Kioxia Corporation
    Inventors: Kazuya SAWADA, Young Min EEH, Tadaaki OIKAWA, Eiji KITAGAWA, Taiga ISODA
  • Patent number: 11217288
    Abstract: According to one embodiment, a magnetic device includes: a first magnetic material provided above a substrate; a second magnetic material provided between the substrate and the first magnetic material; a nonmagnetic material provided between the first magnetic material and the second magnetic material; a first layer provided between the substrate and the second magnetic material and including an amorphous layer; and a second layer provided between the amorphous layer and the second magnetic material and including a crystal layer.
    Type: Grant
    Filed: September 10, 2019
    Date of Patent: January 4, 2022
    Assignee: TOSHIBA MEMORY CORPORATION
    Inventors: Kazuya Sawada, Young Min Eeh, Tadaaki Oikawa, Kenichi Yoshino, Eiji Kitagawa, Taiga Isoda
  • Patent number: 11201189
    Abstract: A semiconductor device includes a first rare earth oxide layer, a first magnetic layer adjacent to the first rare earth oxide layer, a second rare earth oxide layer, a second magnetic layer adjacent to the second rare earth oxide layer, and a nonmagnetic layer. The first magnetic layer is disposed between the first rare earth oxide layer and the nonmagnetic layer and is oriented in a crystal surface which is the same as a crystal surface of the nonmagnetic layer. The second magnetic layer is disposed between the second rare earth oxide layer and the nonmagnetic layer and is oriented in a crystal surface which is the same as a crystal surface of the nonmagnetic layer. The nonmagnetic layer is disposed between the first magnetic layer and the second magnetic layer.
    Type: Grant
    Filed: September 9, 2018
    Date of Patent: December 14, 2021
    Assignee: TOSHIBA MEMORY CORPORATION
    Inventors: Youngmin Eeh, Toshihiko Nagase, Daisuke Watanabe, Kazuya Sawada, Kenichi Yoshino, Tadaaki Oikawa, Hiroyuki Ohtori
  • Patent number: 11127445
    Abstract: According to one embodiment, a magnetic device includes a magnetic tunnel junction element, the magnetic tunnel junction element comprising: a first structure having ferromagnetism; a second structure having ferromagnetism; and a first nonmagnet provided between the first structure and the second structure; wherein: the first structure and the second structure are antiferromagnetically coupled via the first nonmagnet; and the first structure includes a first ferromagnetic nitride.
    Type: Grant
    Filed: March 13, 2019
    Date of Patent: September 21, 2021
    Assignees: TOSHIBA MEMORY CORPORATION, SK HYNIX INC.
    Inventors: Young Min Eeh, Taeyoung Lee, Kazuya Sawada, Eiji Kitagawa, Taiga Isoda, Tadaaki Oikawa, Kenichi Yoshino
  • Publication number: 20210288240
    Abstract: A magnetic memory device includes a magnetoresistance effect element including a first, second, and third ferromagnetic layer, a first non-magnetic layer between the first and second ferromagnetic layer, and a second non-magnetic layer between the second and third ferromagnetic layer. The second ferromagnetic layer is between the first and third ferromagnetic layer. The third ferromagnetic layer includes a fourth ferromagnetic layer in contact with the second non-magnetic layer, a third non-magnetic layer, and a fourth non-magnetic layer between the fourth ferromagnetic layer and the third non-magnetic layer. The first non-magnetic layer includes an oxide including magnesium (Mg). A melting point of the fourth non-magnetic layer is higher than the third non-magnetic layer.
    Type: Application
    Filed: September 9, 2020
    Publication date: September 16, 2021
    Applicant: Kioxia Corporation
    Inventors: Kazuya SAWADA, Young Min EEH, Tadaaki OIKAWA, Eiji KITAGAWA, Taiga ISODA