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: 6751074
    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: May 23, 2003
    Date of Patent: June 15, 2004
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Koichiro Inomata, Kentaro Nakajima, Yoshiaki Saito, Masayuki Sagoi, Tatsuya Kishi
  • Publication number: 20040100818
    Abstract: A write line is covered with a yoke material. The recording layer of an MTJ element is exchange-coupled to the yoke material. The total magnetic volume &Sgr;Msi×ti of the recording layer of the MTJ element and a portion of the yoke material that is exchange-coupled to the recording layer is smaller than the magnetic volume &Sgr;Msi′×ti′ of the remaining portion of the yoke material that covers the write line.
    Type: Application
    Filed: March 6, 2003
    Publication date: May 27, 2004
    Inventors: Hiroaki Yoda, Yoshiaki Asao, Tomomasa Ueda, Junichi Miyamoto, Tatsuya Kishi, Minoru Amano, Takeshi Kajiyama, Hisanori Aikawa
  • Publication number: 20040085681
    Abstract: There is provided a magnetoresistance element including a free layer that includes a first ferromagnetic layer and a second ferromagnetic layer whose magnetization directions are equal to each other and a nonmagnetic film intervening between the first and second ferromagnetic layers, a pinned layer including a third ferromagnetic layer that faces the free layer, and a nonmagnetic layer intervening between the free layer and the pinned layer, the nonmagnetic film containing a material selected from the group including titanium, vanadium, zirconium, niobium, molybdenum, technetium, hafnium, tungsten, rhenium, alloys thereof, semiconductors and insulators.
    Type: Application
    Filed: October 22, 2003
    Publication date: May 6, 2004
    Inventors: Tadashi Kai, Toshihiko Nagase, Tatsuya Kishi, Yoshiaki Saito
  • Patent number: 6730949
    Abstract: A magnetoresistance effect devices having a magnetization free layer free to rotate in an applied magnetic field. The magnetization free layer may include first and second ferromagnetic material layers with a nonmagnetic material layer disposed between the two ferromagnetic material layers. Those ferromagnetic materials are antiferromagnetically coupled with each other at a magnetic coupling field J (−3 [kOe]≦J<0 [kOe]) or ferromagnetically coupled with each other. Alternatively, the magnetization free film includes a first ferromagnetic material layer including a center region having a first magnetization and edge regions having a second magnetization different from the first magnetization and a second ferromagnetic material layer including a center region having a third magnetization parallel to the first magnetization and edge regions having a fourth magnetization different from the third magnetization.
    Type: Grant
    Filed: March 22, 2002
    Date of Patent: May 4, 2004
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Tatsuya Kishi, Minoru Amano, Yoshiaki Saito, Shigeki Takahashi, Kentaro Nakajima, Masayuki Sagoi
  • Publication number: 20040076035
    Abstract: There are provided at least one wire, a magnetoresistive effect element having a storage layer whose magnetization direction varies according to a current magnetic field generated by causing a current to flow in the wire, and first yokes provided so as to be spaced from at least one pair of opposed side faces of the magnetoresistive effect element to form a magnetic circuit in cooperation with the magnetoresistive effect element when a current is caused to flow in the wire. Each of the first yokes has at least two soft magnetic layers which are stacked via a non-magnetic layer.
    Type: Application
    Filed: September 16, 2003
    Publication date: April 22, 2004
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Yoshiaki Saito, Tomomasa Ueda, Tatsuya Kishi, Minoru Amano
  • Patent number: 6717845
    Abstract: A magnetic memory includes: a magnetoresistance effect element having a magnetic recording layer; a first wiring extending in a first direction on or below the magnetoresistance effect element; a covering layer provided at least both sides of the first wiring, the covering layer being made of magnetic material, and the covering layer having a uniaxial anisotropy in the first direction along which a magnetization of the covering layer occurs easily; and a writing circuit configured to pass a current through the first wiring in order to record an information in the magnetic recording layer by a magnetic field generated by the current.
    Type: Grant
    Filed: January 16, 2003
    Date of Patent: April 6, 2004
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Yoshiaki Saito, Katsuya Nishiyama, Shigeki Takahashi, Minoru Amano, Tomomasa Ueda, Hiroaki Yoda, Yoshiaki Asao, Yoshihisa Iwata, Tatsuya Kishi
  • Publication number: 20040062938
    Abstract: There are provided a first reference layer, in which a direction of magnetization is fixed, and a storage layer including a main body, in which a length in an easy magnetization axis direction is longer than a length in a hard magnetization axis direction, and a projecting portion provided to a central portion of the main body in the hard magnetization axis direction, a direction of magnetization of the storage layer being changeable in accordance with an external magnetic field.
    Type: Application
    Filed: September 3, 2003
    Publication date: April 1, 2004
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Tadashi Kai, Shigeki Takahashi, Tomosasa Ueda, Tatsuya Kishi, Yoshiaki Saito
  • Patent number: 6707711
    Abstract: There is provided a magnetic memory including first and second wirings intersecting each other and disposed apart from each other, a magnetoresistance effect film positioned between the first and second wirings, and a first magnetic film including a first portion facing the magnetoresistance effect film with the first wiring interposed therebetween and a pair of second portions positioned on both sides of the first wiring and magnetically connected to the first portion, each of the first and second portions having either one of a high saturation magnetization soft magnetic material containing cobalt and a metal-nonmetal nano-granular film.
    Type: Grant
    Filed: February 4, 2003
    Date of Patent: March 16, 2004
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Yoshiaki Saito, Koichiro Inomata, Minoru Amano, Kentaro Nakajima, Masayuki Sagoi, Tatsuya Kishi, Shigeki Takahashi
  • Publication number: 20040021189
    Abstract: A magnetic memory device includes first wiring which runs in the first direction, second wiring which runs in the second direction, a magneto-resistance element which is arranged at an intersection between the first and second wirings, a first yoke main body which covers at least either of the lower surface and two side surfaces of the first wring, a second yoke main body which covers at least either of the upper surface and two side surfaces of the second wiring, first and second yoke tips which are arranged on two sides of the magneto-resistance element in the first direction at an interval from the magneto-resistance element, and third and fourth yoke tips which are arranged on two sides of the magneto-resistance element in the second direction at an interval from the magneto-resistance element.
    Type: Application
    Filed: March 6, 2003
    Publication date: February 5, 2004
    Inventors: Hiroaki Yoda, Yoshiaki Asao, Tomomasa Ueda, Minoru Amano, Tatsuya Kishi, Keiji Hosotani, Junichi Miyamoto
  • Publication number: 20040004889
    Abstract: A write word line is disposed right under an MTJ element. The write word line extends in an X direction, and a lower surface of the line is coated with a yoke material which has a high permeability. A data selection line (read/write bit line) is disposed right on the MTJ element. A data selection line extends in a Y direction intersecting with the X direction, and an upper surface of the line is coated with the yoke material which has the high permeability. At a write operation time, a magnetic field generated by a write current flowing through a write word line B and data selection line functions on the MTJ element by the yoke material with good efficiency.
    Type: Application
    Filed: April 18, 2003
    Publication date: January 8, 2004
    Inventors: Yoshiaki Asao, Yoshihisa Iwata, Yoshiaki Saito, Hiroaki Yoda, Tomomasa Ueda, Minoru Amano, Shigeki Takahashi, Tatsuya Kishi
  • Publication number: 20030214862
    Abstract: A write word line is disposed right under a MTJ element. The write word line extends in an X direction, and side and lower surfaces of the write word line are coated with a hard magnetic material and yoke material. The hard magnetic material is magnetized by a surplus current passed through the write word line, and a characteristic of the MTJ element is corrected by residual magnetization. A data selection line (read/write bit line) is disposed right on the MTJ element. The data selection line extends in a Y direction intersecting with the X direction, and a part of the surface of the data selection line is coated with the yoke material.
    Type: Application
    Filed: April 22, 2003
    Publication date: November 20, 2003
    Inventors: Yoshiaki Asao, Yoshihisa Iwata, Yoshiaki Saito, Hiroaki Yoda, Tomomasa Ueda, Minoru Amano, Shigeki Takahashi, Tatsuya Kishi
  • Publication number: 20030197984
    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: Application
    Filed: May 23, 2003
    Publication date: October 23, 2003
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Koichiro Inomata, Kentaro Nakajima, Yoshiaki Saito, Masayuki Sagoi, Tatsuya Kishi
  • Publication number: 20030185050
    Abstract: There is provided a magnetoresistance element in which a shape of a free ferromagnetic layer includes a first portion with a parallelogrammic contour, and second portions that protrude from a pair of opposite corners of the first portion respectively in a main direction parallel to a pair of opposite sides of the first portion, the shape is asymmetric with respect to a line that passes through a center of the first portion and is parallel to the main direction, and an axis of easy magnetization of the free ferromagnetic layer falls within a range defined by an acute angle that a first direction makes with a second direction, the first direction being substantially parallel to the main direction and the second direction being substantially parallel to the longest line segment that joins contours of the second portions.
    Type: Application
    Filed: March 19, 2003
    Publication date: October 2, 2003
    Inventors: Tatsuya Kishi, Yoshiaki Saito, Minoru Amano, Shigeki Takahashi, Katsuya Nishiyama, Tomomasa Ueda
  • Publication number: 20030186552
    Abstract: There is provided a magnetic memory device which has a small switching current for a writing line and which has a small variation therein. A method for producing such a magnetic memory device includes: forming a magnetoresistive effect element; forming a first insulating film so as to cover the magnetoresistive effect element; forming a coating film so as to cover the first insulating film; exposing a top face of the magnetoresistive effect element; forming an upper writing line on the magnetoresistive effect element; exposing the first insulating film on a side portion of the magnetoresistive effect element by removing a part or all of the coating film; and forming a yoke structural member so as to cover at least a side portion of the upper writing line and so as to contact the exposed first insulating film on the side portion of the magnetoresistive effect element.
    Type: Application
    Filed: March 26, 2003
    Publication date: October 2, 2003
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Minoru Amano, Tatsuya Kishi, Yoshiaki Saito, Tomomasa Ueda, Hiroaki Yoda
  • Publication number: 20030161181
    Abstract: A magnetic memory includes: a magnetoresistance effect element having a magnetic recording layer; a first wiring extending in a first direction on or below the magnetoresistance effect element; a covering layer provided at least both sides of the first wiring, the covering layer being made of magnetic material, and the covering layer having a uniaxial anisotropy in the first direction along which a magnetization of the covering layer occurs easily; and a writing circuit configured to pass a current through the first wiring in order to record an information in the magnetic recording layer by a magnetic field generated by the current.
    Type: Application
    Filed: January 16, 2003
    Publication date: August 28, 2003
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Yoshiaki Saito, Katsuya Nishiyama, Shigeki Takahashi, Minoru Amano, Tomomasa Ueda, Hiroaki Yoda, Yoshiaki Asao, Yoshihisa Iwata, Tatsuya Kishi
  • Patent number: 6611405
    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: September 14, 2000
    Date of Patent: August 26, 2003
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Koichiro Inomata, Kentaro Nakajima, Yoshiaki Saito, Masayuki Sagoi, Tatsuya Kishi
  • Publication number: 20030156476
    Abstract: A magnetic memory includes: a magnetoresistance effect element having a magnetic recording layer; a first writing wiring extending in a first direction on or below the magnetoresistance effect element, a center of gravity of an axial cross section of the wiring being apart from a center of thickness at the center of gravity, and the center of gravity being eccentric toward the magnetoresistance effect element; and a writing circuit configured to pass a current through the first writing wiring in order to record an information in the magnetic recording layer by a magnetic field generated by the current.
    Type: Application
    Filed: January 16, 2003
    Publication date: August 21, 2003
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Tatsuya Kishi, Minoru Amano, Yoshiaki Saito, Shigeki Takahashi, Katsuya Nishiyama, Yoshiaki Asao, Hiroaki Yoda, Tomomasa Ueda, Yoshihisa Iwata
  • Patent number: 6605836
    Abstract: Magnetoresistance effect devices for attaining magnetically stability and for reducing a switching magnetic field. One of the ferromagnetic layers of the magnetoresistance effect device has a plane shape in which a width of an end portions is wider than a center portion sandwiched by two end portions. The end portions are not symmetrical with respect to an easy magnetization axis or longer axis of the plane shape of ferromagnetic material layer, but are substantially rotationally symmetrical with a center of the plane shape as a pivot. The plane shape may have an S-shape where its magnetic domain is stabilized and the switching magnetic field is reduced. The magnetoresistance effect devices may be used in a magnetic memory apparatus, such as a random access memory, a personal digital assistance, a magnetic reproducing head, and a magnetic information reproducing apparatus.
    Type: Grant
    Filed: March 15, 2002
    Date of Patent: August 12, 2003
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Tatsuya Kishi, Shigeki Takahashi, Kentaro Nakajima, Minoru Amano, Masayuki Sagoi, Yoshiaki Saito
  • Publication number: 20030137028
    Abstract: A semiconductor integrated circuit device includes a cell transistor, a bit line, an intracell local interconnection and a magnetoresistive element. The intracell local interconnection provided above the bit line and electrically connected to one of source and drain regions of the cell transistor. The magnetoresistive element provided on the bit line and electrically connected to the bit line and the intracell local interconnection.
    Type: Application
    Filed: July 22, 2002
    Publication date: July 24, 2003
    Inventors: Keiji Hosotani, Yoshiaki Asao, Yoshiaki Saito, Minoru Amono, Shigeki Takahashi, Tatsuya Kishi, Yoshihisa Iwata
  • Publication number: 20030137870
    Abstract: There is provided a magnetic memory including first and second wirings intersecting each other and disposed apart from each other, a magnetoresistance effect film positioned between the first and second wirings, and a first magnetic film including a first portion facing the magnetoresistance effect film with the first wiring interposed therebetween and a pair of second portions positioned on both sides of the first wiring and magnetically connected to the first portion, each of the first and second portions having either one of a high saturation magnetization soft magnetic material containing cobalt and a metal-nonmetal nano-granular film.
    Type: Application
    Filed: February 4, 2003
    Publication date: July 24, 2003
    Inventors: Yoshiaki Saito, Koichiro Inomata, Minoru Amano, Kentaro Nakajima, Masayuki Sagoi, Tatsuya Kishi, Shigeki Takahashi