Patents by Inventor Hisao Matsutera

Hisao Matsutera 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: 7372673
    Abstract: In a magnetoresistive effect transducer including a pinning layer, a pinned layer, a free layer and a non-magnetic layer inserted between the pinned layer and the free layer, a longitudinal bias layer is connected directly to a part of the free layer to apply a bias magnetic field to the free layer, thus biasing a magnetization direction of the free layer so that the magnetization direction of the free layer coincides with that of the longitudinal bias layer.
    Type: Grant
    Filed: May 31, 2005
    Date of Patent: May 13, 2008
    Assignee: NEC Corporation
    Inventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Tsutomu Ishi, Hiroaki Honjou, Kunihiko Ishihara, Jun-Ichi Fujikata, Hisao Matsutera, Hisanao Tsuge, Atsushi Kamijo
  • Patent number: 7126201
    Abstract: A technique is provided in which an offset magnetic field of a memory cell of a MRAM is reduced more effectively. The MRAM of the present invention is composed of a free layer (11) which has a reversible free spontaneous magnetization, a fixed layer (6) which has fixed spontaneous magnetization, and a spacer layer (10) formed of non-magnetic interposed between the free layer (11) and the fixed layer (6). The fixed layer (6) is formed such that orange peel effect and magneto-static coupling effect does not substantially influence on the free layer (11).
    Type: Grant
    Filed: July 3, 2003
    Date of Patent: October 24, 2006
    Assignee: NEC Corporation
    Inventors: Hisao Matsutera, Hideaki Numata
  • Patent number: 7099184
    Abstract: An improved magnetic random access memory (MRAM) has two sets of signal lines where each set is substantially perpendicular to the other, and memory cells located at the intersections of the signal lines. Each memory cell has a magneto-resistant element containing a magnetization layer whose magnetic characteristics change depending on the intensity of the magnetic field applied. A desired magnetic field can be applied to any cell by supplying appropriate write currents to the signal lines intersecting at that cell. The relationship between applied magnetic fields, two different threshold function values, and four different magnetic fields that result at each cell is disclosed. Better performance, namely, improved selectivity and a more stable write operation, results.
    Type: Grant
    Filed: July 28, 2003
    Date of Patent: August 29, 2006
    Assignee: NEC Corporation
    Inventors: Tadahiko Sugibayashi, Takeshi Honda, Noboru Sakimura, Hisao Matsutera, Atsushi Kamijo, Kenichi Shimura, Kaoru Mori
  • Patent number: 7068536
    Abstract: In an aspect of the present invention, a magnetic random access memory includes a substrate, a MTJ (Magnetic tunnel Junction) device formed above the substrate, a first wiring line formed above the substrate, and a second wiring line formed above the substrate. The MTJ device includes a pinned ferromagnetic layer which has a pinned magnetization, a free ferromagnetic lamination layer, and a tunnel barrier layer interposed between the pinned ferromagnetic layer and the free ferromagnetic lamination layer.
    Type: Grant
    Filed: October 23, 2003
    Date of Patent: June 27, 2006
    Assignee: NEC Corporation
    Inventors: Hisao Matsutera, Tetsuhiro Suzuki
  • Publication number: 20060098477
    Abstract: A magnetic random access memory is composed of a plurality of first signal lines provided to extend in a first direction, a plurality of second signal lines provided to extend in a second direction substantially perpendicular to the first direction, a plurality of memory cells respectively provided at the intersections of the plurality of first signal lines and the plurality of second signal lines, and a plurality of magnetic structures respectively provided to the plurality of memory cells. Each of the plurality of memory cells has a magneto-resistance element containing a spontaneous magnetization layer which has a first threshold function, and the direction of the spontaneous magnetization of the spontaneous magnetization layer is reversed when an element applied magnetic field having the intensity equal to or larger than a first threshold function value is applied.
    Type: Application
    Filed: July 28, 2003
    Publication date: May 11, 2006
    Inventors: Tadahiko Sugibayashi, Takeshi Honda, Noboru Sakimura, Hisao Matsutera, Atsushi Kamijo, Kenichi Shimura
  • Publication number: 20050242407
    Abstract: A technique is provided in which an offset magnetic field of a memory cell of a MRAM is reduced more effectively. The MRAM of the present invention is composed of a free layer (11) which has a reversible free spontaneous magnetization, a fixed layer (6) which has fixed spontaneous magnetization, and a spacer layer (10) formed of non-magnetic interposed between the free layer (11) and the fixed layer (6). The fixed layer (6) is formed such that orange peel effect and magneto-static coupling effect does not substantially influence on the free layer (11).
    Type: Application
    Filed: July 3, 2003
    Publication date: November 3, 2005
    Inventors: Hisao Matsutera, Hideaki Numata
  • Publication number: 20050219772
    Abstract: In a magnetoresistive effect transducer including a pinning layer, a pinned layer, a free layer and a non-magnetic layer inserted between the pinned layer and the free layer, a longitudinal bias layer is connected directly to a part of the free layer to apply a bias magnetic field to the free layer, thus biasing a magnetization direction of the free layer so that the magnetization direction of the free layer coincides with that of the longitudinal bias layer.
    Type: Application
    Filed: May 31, 2005
    Publication date: October 6, 2005
    Applicant: NEC Corporation
    Inventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Tsutomu Ishi, Hiroaki Honjou, Kunihiko Ishihara, Jun-Ichi Fujikata, Hisao Matsutera, Hisanao Tsuge, Atsushi Kamijo
  • Patent number: 6950290
    Abstract: In a magnetoresistive effect transducer including a pinning layer, a pinned layer, a free layer and a non-magnetic layer inserted between the pinned layer and the free layer, a longitudinal bias layer is connected directly to a part of the free layer to apply a bias magnetic field to the free layer, thus biasing a magnetization direction of the free layer so that the magnetization direction of the free layer coincides with that of the longitudinal bias layer.
    Type: Grant
    Filed: September 12, 2002
    Date of Patent: September 27, 2005
    Assignee: NEC Corporation
    Inventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Tsutomu Ishi, Hiroaki Honjou, Kunihiko Ishihara, Jun-Ichi Fujikata, Hisao Matsutera, Hisanao Tsuge, Atsushi Kamijo
  • Publication number: 20050002229
    Abstract: In an aspect of the present invention, a magnetic random access memory includes a substrate, a MTJ (Magnetic tunnel Junction) device formed above the substrate, a first wiring line formed above the substrate, and a second wiring line formed above the substrate. The MTJ device includes a pinned ferromagnetic layer which has a pinned magnetization, a free ferromagnetic lamination layer, and a tunnel barrier layer interposed between the pinned ferromagnetic layer and the free ferromagnetic lamination layer.
    Type: Application
    Filed: October 23, 2003
    Publication date: January 6, 2005
    Inventors: Hisao Matsutera, Tetsuhiro Suzuki
  • Patent number: 6639766
    Abstract: A magneto-resistance effect (“MR”) type composite head includes a reproduction head with an MR element arranged between a first and a second magnetic shield; and a recording head arranged adjacent to the reproduction head so as to use the second magnetic shield as a first magnetic pole film and having a second magnetic pole film opposing to the first magnetic pole via a magnetic gap; the MR element includes a center region including a ferromagnetic tunnel junction magneto-resistance effect film having a first ferromagnetic layer and a second ferromagnetic layer for generating a magneto-resistance effect using the first and the second magnetic shields as electrodes so that a current flows in an almost vertical direction between the first and the second magnetic shields; a tunnel barrier layer provided between the first and the second ferromagnetic layer; and an end region arranged to sandwich the center region from both sides for /applying a bias magnetic field to the center region.
    Type: Grant
    Filed: October 24, 2001
    Date of Patent: October 28, 2003
    Assignee: NEC Corporation
    Inventors: Ishiwata Nobuyuki, Hisanao Tsuge, Hisao Matsutera, Yuji Tsukamoto, Masafumi Nakada, Atsushi Kamijo
  • Patent number: 6542342
    Abstract: In a magnetoresistive effect transducer including a pinning layer, a pinned layer, a free layer and a non-magnetic layer inserted between the pinned layer and the free layer, a longitudinal bias layer is connected directly to a part of the free layer to apply a bias magnetic field to the free layer, thus biasing a magnetization direction of the free layer so that the magnetization direction of the free layer coincides with that of the longitudinal bias layer.
    Type: Grant
    Filed: November 29, 1999
    Date of Patent: April 1, 2003
    Assignee: NEC Corporation
    Inventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Tsutomu Ishi, Hiroaki Honjou, Kunihiko Ishihara, Jun-Ichi Fujikata, Hisao Matsutera, Hisanao Tsuge, Atsushi Kamijo
  • Publication number: 20030035256
    Abstract: In a magnetoresistive effect transducer including a pinning layer, a pinned layer, a free layer and a non-magnetic layer inserted between the pinned layer and the free layer, a longitudinal bias layer is connected directly to a part of the free layer to apply a bias magnetic field to the free layer, thus biasing a magnetization direction of the free layer so that the magnetization direction of the free layer coincides with that of the longitudinal bias layer.
    Type: Application
    Filed: September 12, 2002
    Publication date: February 20, 2003
    Applicant: NEC Corporation
    Inventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Tsutomu Ishi, Hiroaki Honjou, Kunihiko Ishihara, Jun-Ichi Fujikata, Hisao Matsutera, Hisanao Tsuge, Atsushi Kamijo
  • Patent number: 6490139
    Abstract: A magneto-resistive element comprises a first electrode, a magneto-resistive layer formed on the first electrode in which resistance is changed in accordance with magnetic field, and a second electrode layer formed on the magneto-resistive layer. The magneto-resistive layer has a first magnetic layer formed on the first electrode, a non-magnetic layer formed on the first magnetic layer, and a second magnetic layer formed on the non-magnetic layer. The average surface roughness of the first electrode is equal to or smaller than 0.3 nm. Since the first electrode has such the small average surface roughness, the non-magnetic layer formed on the first electrode layer is flattened, thus, current leakage is prevented. The first electrode is made of at least one of Ta, Zr, Ti, Hf, W, Mo, Y, V, Nb, Au, Ag, Pd, and Pt which has strong bond strength. Since the first electrode has strong bond strength, exfoliation of the first electrode from the layers contacting the first electrode does not occur.
    Type: Grant
    Filed: January 27, 2000
    Date of Patent: December 3, 2002
    Assignee: NEC Corporation
    Inventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Hisao Matsutera, Hisanao Tsuge, Atsushi Kamijo
  • Publication number: 20020027753
    Abstract: A magneto-resistance effect (“MR”) type composite head includes a reproduction head with an MR element arranged between a first and a second magnetic shield; and a recording head arranged adjacent to the reproduction head so as to use the second magnetic shield as a first magnetic pole film and having a second magnetic pole film opposing to the first magnetic pole via a magnetic gap; the MR element includes a center region including a ferromagnetic tunnel junction magneto-resistance effect film having a first ferromagnetic layer and a second ferromagnetic layer for generating a magneto-resistance effect using the first and the second magnetic shields as electrodes so that a current flows in an almost vertical direction between the first and the second magnetic shields; a tunnel barrier layer provided between the first and the second ferromagnetic layer; and an end region arranged to sandwich the center region from both sides for /applying a bias magnetic field to the center region.
    Type: Application
    Filed: October 24, 2001
    Publication date: March 7, 2002
    Applicant: NEC Corporation
    Inventors: Nobuyuki Ishiwata, Hisanao Tsuge, Hisao Matsutera, Yuji Tsukamoto, Masafumi Nakada, Atsushi Kamijo
  • Patent number: 6341053
    Abstract: The present invention provides a magnetic tunnel junction device for an external magnetic field sensor. The device comprises a stack of multi-layers, which include a first antiferromagnetic pinning layer, a ferromagnetic free layer, a tunneling barrier layer, a ferromagnetic pinned layer, and a second antiferromagnetic pinning layer. The first pinning layer has a first pinning field, which pins a magnetization of the free layer in a track width direction. The second pinning layer has a second pinning field, which pins a magnetization of the pinned layer in a direction in the plane of the stacked layers of the magnetic tunnel junction, along the applied external magnetic field direction.
    Type: Grant
    Filed: October 30, 1998
    Date of Patent: January 22, 2002
    Assignee: NEC Corporation
    Inventors: Masafumi Nakada, Hisanao Tsuge, Yuji Tsukamoto, Hisao Matsutera, Nobuyuki Ishiwata, Atsushi Kamijo
  • Patent number: 6333842
    Abstract: The present invention provides a magneto-resistance effect (hereinafter, referred to as MR) type composite head.
    Type: Grant
    Filed: December 3, 1998
    Date of Patent: December 25, 2001
    Assignee: NEC Corporation
    Inventors: Ishiwata Nobuyuki, Hisanao Tsuge, Hisao Matsutera, Yuji Tsukamoto, Masafumi Nakada, Atsushi Kamijo
  • Patent number: 6174736
    Abstract: There is provided a method of fabricating a ferromagnetic tunnel junction device, including the steps of (a) forming a first ferromagnetic layer on a substrate, (b) forming a tunnel barrier layer on the first ferromagnetic layer, (c) forming a second ferromagnetic layer on the tunnel barrier layer, (d) mechanically polishing end surfaces of the first ferromagnetic layer, the tunnel barrier layer, and the second ferromagnetic layer, and (e) etching the surfaces of the first ferromagnetic layer, the tunnel barrier layer, and the second ferromagnetic layer. The method provides a ferromagnetic tunnel junction device having a height defined with high accuracy, and including a tunnel barrier layer keeping first and second ferromagnetic layers in electrical isolation with each other.
    Type: Grant
    Filed: December 11, 1998
    Date of Patent: January 16, 2001
    Assignee: NEC Corporation
    Inventors: Yuji Tsukamoto, Hisanao Tsuge, Nobuyuki Ishiwata, Hisao Matsutera, Masafumi Nakada, Atsushi Kamijo