Patents by Inventor Tatsuya Kishi

Tatsuya Kishi 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: 7768824
    Abstract: The present invention provides a low-resistance magnetoresistive element of a spin-injection write type. A crystallization promoting layer that promotes crystallization is formed in contact with an interfacial magnetic layer having an amorphous structure, so that crystallization is promoted from the side of a tunnel barrier layer, and the interface between the tunnel barrier layer and the interfacial magnetic layer is adjusted. With this arrangement, it is possible to form a magnetoresistive element that has a low resistance so as to obtain a desired current value, and has a high TMR ratio.
    Type: Grant
    Filed: September 16, 2008
    Date of Patent: August 3, 2010
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Masatoshi Yoshikawa, Eiji Kitagawa, Tadaomi Daibou, Toshihiko Nagase, Tatsuya Kishi, Hiroaki Yoda
  • Publication number: 20100118600
    Abstract: A magnetoresistive element which records information by supplying spin-polarized electrons to a magnetic material, includes a first pinned layer which is made of a magnetic material and has a first magnetization directed in a direction perpendicular to a film surface, a free layer which is made of a magnetic material and has a second magnetization directed in the direction perpendicular to the film surface, the direction of the second magnetization reversing by the spin-polarized electrons, and a first nonmagnetic layer which is provided between the first pinned layer and the free layer. A saturation magnetization Ms of the free layer satisfies a relationship 0?Ms<?{square root over ( )}{Jw/(6?At)}. Jw is a write current density, t is a thickness of the free layer, A is a constant.
    Type: Application
    Filed: January 12, 2010
    Publication date: May 13, 2010
    Inventors: Toshihiko NAGASE, Masatoshi Yoshikawa, Eiji Kitagawa, Masahiko Nakayama, Tadashi Kai, Tatsuya Kishi, Hiroaki Yoda
  • Publication number: 20100080050
    Abstract: A magnetic memory includes a magnetoresistive effect device comprising: a first ferromagnetic layer that has magnetic anisotropy in a direction perpendicular to a film plane thereof; a first nonmagnetic layer that is provided on the first ferromagnetic layer; a first reference layer that is provided on the first nonmagnetic layer, has magnetic anisotropy in a direction perpendicular to a film plane thereof, has magnetization antiparallel to a magnetization direction of the first ferromagnetic layer, and has a film thickness that is 1/5.2 to 1/1.
    Type: Application
    Filed: September 10, 2009
    Publication date: April 1, 2010
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Jyunichi OZEKI, Naoharu SHIMOMURA, Sumio IKEGAWA, Tadashi KAI, Masahiko NAKAYAMA, Hisanori AIKAWA, Tatsuya KISHI, Hiroaki YODA, Eiji KITAGAWA, Masatoshi YOSHIKAWA
  • Patent number: 7663197
    Abstract: A magnetoresistive element which records information by supplying spin-polarized electrons to a magnetic material, includes a first pinned layer which is made of a magnetic material and has a first magnetization directed in a direction perpendicular to a film surface, a free layer which is made of a magnetic material and has a second magnetization directed in the direction perpendicular to the film surface, the direction of the second magnetization reversing by the spin-polarized electrons, and a first nonmagnetic layer which is provided between the first pinned layer and the free layer. A saturation magnetization Ms of the free layer satisfies a relationship 0?Ms<?{square root over ( )}{Jw/(6?At)}. Jw is a write current density, t is a thickness of the free layer, A is a constant.
    Type: Grant
    Filed: September 22, 2006
    Date of Patent: February 16, 2010
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Toshihiko Nagase, Masatoshi Yoshikawa, Eiji Kitagawa, Masahiko Nakayama, Tadashi Kai, Tatsuya Kishi, Hiroaki Yoda
  • Patent number: 7633795
    Abstract: A write control method for a magnetoresistive random access memory, which includes a memory cell having a recording layer with an axis of easy magnetization and an axis of hard magnetization. The write control method includes writing a datum into the memory cell. The writing of the datum includes applying a pulsative first magnetic field substantially parallel to the axis of easy magnetization of the recording layer and a pulsative second magnetic field substantially parallel to the axis of hard magnetization to the recording layer so as to cause a period of the pulsative first magnetic field and a period of the pulsative second magnetic field to overlap each other, and applying a pulsative third magnetic field having substantially the same direction as the pulsative first magnetic field to the recording layer at least once after applying the pulsative first magnetic field to the recording layer.
    Type: Grant
    Filed: September 20, 2006
    Date of Patent: December 15, 2009
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Naoharu Shimomura, Tatsuya Kishi, Ryousuke Takizawa
  • Publication number: 20090251951
    Abstract: A magnetoresistive element includes a foundation layer, a first magnetic layer on the foundation layer, a tunnel barrier layer on the first magnetic layer, and a second magnetic layer on the tunnel barrier layer. The first magnetic layer is made of a ferromagnetic metal containing one or more elements selected from a first group consisting of Co, Fe, and Ni, and one or more elements selected from a second group consisting of Cu, Ag, Au, Pd, Pt, Ru, Rh, Ir, and Os. The foundation layer is made of a metal containing one or more elements selected from a third group consisting of Al, Ni, Co, Fe, Mn, Cr, and V.
    Type: Application
    Filed: March 24, 2009
    Publication date: October 8, 2009
    Inventors: Masatoshi Yoshikawa, Eiji Kitagawa, Tadaomi Daibou, Makoto Nagamine, Tatsuya Kishi, Hiroaki Yoda
  • Patent number: 7599156
    Abstract: A magnetoresistive element according to an example of the present invention has a stacked structure comprised first and second ferromagnetic layers and a nonmagnetic layer disposed between these ferromagnetic layers, and a planar shape of at least one of the first and second ferromagnetic layers has a shape formed by combining two or more parts each having a shape of a character C.
    Type: Grant
    Filed: October 6, 2005
    Date of Patent: October 6, 2009
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Tatsuya Kishi, Masahiko Nakayama, Yoshiaki Fukuzumi, Tadashi Kai
  • Publication number: 20090243008
    Abstract: A magnetoresistive element includes an underlying layer having a cubic or tetragonal crystal structure oriented in a (001) plane, a first magnetic layer provided on the underlying layer, having perpendicular magnetic anisotropy, and having an fct structure oriented in a (001) plane, a non-magnetic layer provided on the first magnetic layer, and a second magnetic layer provided on the non-magnetic layer, and having perpendicular magnetic anisotropy. An in-plane lattice constant a1 of the underlying layer and an in-plane lattice constant a2 of the first magnetic layer satisfy the following equation in which b is a magnitude of Burgers vector of the first magnetic layer, ? is an elastic modulus of the first magnetic layer, and hc is a thickness of the first magnetic layer.
    Type: Application
    Filed: March 24, 2009
    Publication date: October 1, 2009
    Inventors: Eiji Kitagawa, Masatoshi Yoshikawa, Toshihiko Nagase, Tadaomi Daibou, Makoto Nagamine, Katsuya Nishiyama, Tatsuya Kishi, Hiroaki Yoda
  • Publication number: 20090244792
    Abstract: A magnetoresistance effect element includes: a first ferromagnetic layer having invariable magnetization perpendicular to a film plane; a second ferromagnetic layer having variable magnetization perpendicular to the film plane; a first nonmagnetic layer interposed between the first ferromagnetic layer and the second ferromagnetic layer; a third ferromagnetic layer provided on an opposite side of the second ferromagnetic layer from the first nonmagnetic layer, and having variable magnetization parallel to the film plane; and a second nonmagnetic layer interposed between the second and third ferromagnetic layers.
    Type: Application
    Filed: March 3, 2009
    Publication date: October 1, 2009
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Masahiko NAKAYAMA, Tadashi KAI, Sumio IKEGAWA, Hiroaki YODA, Tatsuya KISHI
  • Patent number: 7596015
    Abstract: A magnetoresistive element includes a free layer which contains a magnetic material and has an fct crystal structure with a (001) plane oriented, the free layer having a magnetization which is perpendicular to a film plane and has a direction to be changeable by spin-polarized electrons, a first nonmagnetic layer and a second nonmagnetic layer which sandwich the free layer and have one of a tetragonal crystal structure and a cubic crystal structure, and a fixed layer which is provided on only one side of the free layer and on a surface of the first nonmagnetic layer opposite to a surface with the free layer and contains a magnetic material, the fixed layer having a magnetization which is perpendicular to a film plane and has a fixed direction.
    Type: Grant
    Filed: August 1, 2007
    Date of Patent: September 29, 2009
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Eiji Kitagawa, Toshihiko Nagase, Masatoshi Yoshikawa, Katsuya Nishiyama, Tatsuya Kishi, Hiroaki Yoda
  • Patent number: 7593193
    Abstract: A magnetoresistive element has a ferromagnetic double tunnel junction having a stacked structure of a first antiferromagnetic layer/a first ferromagnetic layer/a first dielectric layer/a second ferromagnetic layer/a second dielectric layer/a third ferromagnetic layer/a second antiferromagnetic layer. The second ferromagnetic layer that is a free layer consists of a Co-based alloy or a three-layered film of a Co-based alloy/a Ni—Fe alloy/a Co-based alloy. A tunnel current is flowed between the first ferromagnetic layer and the third ferromagnetic layer.
    Type: Grant
    Filed: August 30, 2007
    Date of Patent: September 22, 2009
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Koichiro Inomata, Kentaro Nakajima, Yoshiaki Saito, Masayuki Sagoi, Tatsuya Kishi
  • Publication number: 20090224342
    Abstract: A magnetoresistive effect element includes a reference layer, a recording layer, and a nonmagnetic layer. The reference layer is made of a magnetic material, has an invariable magnetization which is perpendicular to a film surface. The recording layer is made of a magnetic material, has a variable magnetization which is perpendicular to the film surface. The nonmagnetic layer is arranged between the reference layer and the recording layer. A critical diameter which is determined by magnetic anisotropy, saturation magnetization, and switched connection of the recording layer and has a single-domain state as a unique stable state or a critical diameter which has a single-domain state as a unique stable state and is inverted while keeping the single-domain state in an inverting process is larger than an element diameter of the magnetoresistive effect element.
    Type: Application
    Filed: October 9, 2008
    Publication date: September 10, 2009
    Inventors: Masahiko NAKAYAMA, Kay Yakushiji, Sumio Ikegawa, Shinji Yuasa, Tadashi Kai, Toshihiko Nagase, Minoru Amano, Hisanori Aikawa, Tatsuya Kishi, Hiroaki Yoda
  • Patent number: 7564109
    Abstract: A magnetic memory device includes a first write wiring line including a wiring layer formed in a trench in an insulation layer, a barrier metal layer buried in the trench over the wiring layer. And the device includes a magneto-resistance effect element provided on the first write wiring line.
    Type: Grant
    Filed: August 13, 2004
    Date of Patent: July 21, 2009
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Takeshi Kajiyama, Hisanori Aikawa, Tomomasa Ueda, Tatsuya Kishi, Masatoshi Yoshikawa
  • Publication number: 20090140358
    Abstract: A magnetoresistive element includes a first ferromagnetic layer having a first magnetization, the first magnetization having a first pattern when the magnetoresistive element is half-selected during a first data write, a second pattern when the magnetoresistive element is selected during a second data write, and a third pattern of residual magnetization, the first pattern being different from the second and third pattern, a second ferromagnetic layer having a second magnetization, and a nonmagnetic layer arranged between the first ferromagnetic layer and the second ferromagnetic layer and having a tunnel conductance changing dependent on a relative angle between the first magnetization and the second magnetization.
    Type: Application
    Filed: February 2, 2009
    Publication date: June 4, 2009
    Inventors: Masahiko Nakayama, Tadashi Kai, Tatsuya Kishi, Yoshiaki Fukuzumi, Toshihiko Nagase, Sumio Ikegawa, Hiroaki Yoda
  • Patent number: 7518907
    Abstract: A magnetoresistive element includes a first ferromagnetic layer having a first magnetization, the first magnetization having a first pattern when the magnetoresistive element is half-selected during a first data write, a second pattern when the magnetoresistive element is selected during a second data write, and a third pattern of residual magnetization, the first pattern being different from the second and third pattern, a second ferromagnetic layer having a second magnetization, and a nonmagnetic layer arranged between the first ferromagnetic layer and the second ferromagnetic layer and having a tunnel conductance changing dependent on a relative angle between the first magnetization and the second magnetization.
    Type: Grant
    Filed: January 25, 2008
    Date of Patent: April 14, 2009
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Masahiko Nakayama, Tadashi Kai, Tatsuya Kishi, Yoshiaki Fukuzumi, Toshihiko Nagase, Sumio Ikegawa, Hiroaki Yoda
  • Publication number: 20090080239
    Abstract: A magnetoresistive element includes a first reference layer having magnetic anisotropy perpendicular to a film surface, and an invariable magnetization, a recording layer having a stacked structure formed by alternately stacking magnetic layers and nonmagnetic layers, magnetic anisotropy perpendicular to a film surface, and a variable magnetization, and an intermediate layer provided between the first reference layer and the recording layer, and containing a nonmagnetic material. The magnetic layers include a first magnetic layer being in contact with the intermediate layer and a second magnetic layer being not in contact with the intermediate layer. The first magnetic layer contains an alloy containing cobalt (Co) and iron (Fe), and has a film thickness larger than that of the second magnetic layer.
    Type: Application
    Filed: September 18, 2008
    Publication date: March 26, 2009
    Inventors: Toshihiko Nagase, Katsuya Nishiyama, Tadashi Kai, Masahiko Nakayama, Makoto Nagamine, Minoru Amano, Masatoshi Yoshikawa, Tatsuya Kishi, Hiroaki Yoda
  • Publication number: 20090080238
    Abstract: The present invention provides a low-resistance magnetoresistive element of a spin-injection write type. A crystallization promoting layer that promotes crystallization is formed in contact with an interfacial magnetic layer having an amorphous structure, so that crystallization is promoted from the side of a tunnel barrier layer, and the interface between the tunnel barrier layer and the interfacial magnetic layer is adjusted. With this arrangement, it is possible to form a magnetoresistive element that has a low resistance so as to obtain a desired current value, and has a high TMR ratio.
    Type: Application
    Filed: September 16, 2008
    Publication date: March 26, 2009
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Masatoshi YOSHIKAWA, Eiji Kitagawa, Tadaomi Daibou, Toshihiko Nagase, Tatsuya Kishi, Hiroaki Yoda
  • Publication number: 20090080124
    Abstract: A magnetoresistive element includes: a first magnetization reference layer having magnetization perpendicular to a film plane, a direction of the magnetization being invariable in one direction; a magnetization free layer having magnetization perpendicular to the film plane, a direction of the magnetization being variable; a first intermediate layer provided between the first magnetization reference layer and the magnetization free layer; a magnetic phase transition layer provided on an opposite side of the magnetization free layer from the first intermediate layer, the magnetic phase transition layer being magnetically coupled to the magnetization free layer, and being capable of bidirectionally performing a magnetic phase transition between an antiferromagnetic material and a ferromagnetic material; and an excitation layer provided on an opposite side of the magnetic phase transition layer from the magnetization free layer, and causing the magnetic phase transition layer to perform the magnetic phase transi
    Type: Application
    Filed: September 15, 2008
    Publication date: March 26, 2009
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Masatoshi Yoshikawa, Tadaomi Daibou, Eiji Kitagawa, Toshihiko Nagase, Tatsuya Kishi, Hiroaki Yoda
  • Publication number: 20090079018
    Abstract: A magnetoresistive element includes a first underlying layer having an NaCl structure and containing a nitride orienting in a (001) plane, a first magnetic layer provided on the first underlying layer, having magnetic anisotropy perpendicular to a film surface, having an L10 structure, and containing a ferromagnetic alloy orienting in a (001) plane, a first nonmagnetic layer provided on the first magnetic layer, and a second magnetic layer provided on the first nonmagnetic layer and having magnetic anisotropy perpendicular to a film surface.
    Type: Application
    Filed: September 18, 2008
    Publication date: March 26, 2009
    Inventors: Toshihiko Nagase, Masatoshi Yoshikawa, Eiji Kitagawa, Katsuya Nishiyama, Tadaomi Daibou, Tatsuya Kishi, Hiroaki Yoda
  • Patent number: 7494724
    Abstract: A method of manufacturing a magnetoresistance effect element includes forming an insulating layer on a first ferromagnetic layer, forming an aperture reaching the first ferromagnetic layer by thrusting a needle from the top surface of the insulating layer, and depositing a ferromagnetic material to form a second ferromagnetic layer overlying the insulating layer which buries the aperture. The aperture can have an opening width not larger than 20 nm. A current flowing between the first ferromagnetic layer and the needle can be monitored, and thrusting of the needle an be interrupted when the current reaches a predetermined value.
    Type: Grant
    Filed: July 3, 2007
    Date of Patent: February 24, 2009
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Shiho Okuno, Yuichi Ohsawa, Shigeru Haneda, Yuzo Kamiguchi, Tatsuya Kishi