Patents by Inventor Nobuyuki Ishiwata

Nobuyuki Ishiwata 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: 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: 6493195
    Abstract: A magnetoresistance element includes a lower electrode layer, a magnetoresistance effect layer, an upper electrode layer and a lower electrode anti-erosion/flaking layer. The lower electrode anti-erosion/flaking layer, which is formed before a photoresist layer remaining on the patterned lower electrode layer is removed, is formed around the lower electrode layer so that its edge facing the lower electrode layer will be in contact with the edge of the lower electrode layer.
    Type: Grant
    Filed: August 30, 2000
    Date of Patent: December 10, 2002
    Assignee: NEC Corporation
    Inventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Eizo Fukami, Hiroaki Honjo, 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: 20020164828
    Abstract: In a tunneling magnetoresistance transducer including first and second ferromagnetic layers and a tunnel barrier layer made of insulating material sandwiched by the first and second ferromagnetic layers, the resistance of the tunnel barrier layer remains essentially constant independent of the temperature of the transducer.
    Type: Application
    Filed: June 4, 2002
    Publication date: November 7, 2002
    Applicant: NEC CORPORATION
    Inventors: Nobuyuki Ishiwata, Keishi Ohashi, Hisanao Tsuge
  • Patent number: 6466416
    Abstract: Disclosed is a magnetic heads suitable for high density recording which comprises an ID head where a CoNiFe film or a CoNiFeX film is formed by a physical vapor deposition method and further a plated film of CoNiFe etc. is formed while avoiding vanishment of a seed layer. The ID head shows high reliability and high production efficiency. The upper magnetic pole of the ID head is composed of a laminated layers of a first magnetic layer 13 of a CoNiFe film or a CoNiFeX film which is formed by a physical vapor deposition method, a second magnetic layer 14 of NiFe layer composing a seed layer laminated thereon, and a third magnetic layer 11 of CoNiFe plated film etc. further laminated on the second layer.
    Type: Grant
    Filed: November 7, 2000
    Date of Patent: October 15, 2002
    Assignee: NEC Corporation
    Inventors: Hiroaki Honjo, Nobuyuki Ishiwata, Tsutomu Ishi, Mikiko Saito, Shinsaku Saito, Tamaki Toba, Yoshihiro Nonaka
  • Patent number: 6452204
    Abstract: In a tunneling magnetoresistance transducer including first and second ferromagnetic layers and a tunnel barrier layer made of insulating material sandwiched by the first and second ferromagnetic layers, the resistance of the tunnel barrier layer remains essentially constant independent of the temperature of the transducer.
    Type: Grant
    Filed: December 8, 1999
    Date of Patent: September 17, 2002
    Assignee: NEC Corporation
    Inventors: Nobuyuki Ishiwata, Keishi Ohashi, Hisanao Tsuge
  • Publication number: 20020097540
    Abstract: A magneto-resistance effect head is provided with a lower conductive layer which is provided with a recessed portion, and a vertical bias layer is provided in the recessed portion. A free layer is provided on the lower conductive layer. On the free layer, layered in the following order are the non-magnetic layer, the fixed layer, the fixing layer, and the upper layer so as not to be placed immediately above the vertical bias layer. The non-magnetic layer, the fixed layer, the fixing layer, and the upper layer are buried in an insulation layer. Furthermore, an upper conductive layer is provided on the upper layer and the insulation layer. In the direction of the magnetic field applied by the vertical bias layer, the free layer is made greater in length than the fixed layer and the free layer is disposed in proximity to the vertical bias layer with the distance between the fixed layer and the vertical bias layer remaining unchanged.
    Type: Application
    Filed: July 30, 2001
    Publication date: July 25, 2002
    Inventors: Kazuhiko Hayashi, Junichi Fujikata, Tsutomu Ishi, Shigeru Mori, Keishi Ohashi, Masafumi Nakada, Kiyokazu Nagahara, Kunihiko Ishihara, Nobuyuki Ishiwata
  • Patent number: 6392851
    Abstract: Disclosed is a magnetroresistance effect type complex head including: (1) a magnetroresistance effect head including: a magnetroresistance effect element 15 which includes a central region 12 for detecting a magnetic field from a record medium and a pair of terminal portions 13, 14 for supplying a bias magnetic field and a current to the central region; a pair of magnetic separators 11, 16 confronting each other, sandwiching the magnetroresistance effect element, and each including an insulator; and a first and second magnetic shield films 10, 17 confronting each other, and sandwitching the magnetroresistance effect element and the pair of magnetic separators; (2) an inductive head including: a first magnetic pole film 17 which is also used as the second magnetic shield; a magnetic gap 18 piled up on the first magnetic pole; a second magnetic pole film 19 piled up on the magnetic gap; and a coil pattern for generating a magnetic flux which flows through the first and second magnetic pole films; (3) a pair of
    Type: Grant
    Filed: September 21, 1999
    Date of Patent: May 21, 2002
    Assignee: NEC Corporation
    Inventors: Nobuyuki Ishiwata, Tsutomu Ishi
  • 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
  • Publication number: 20020008016
    Abstract: A magnetoresistive effect sensor uses a shielded-type magnetoresistive effect element using a magnetoresistive effect film formed by a basic configuration of a combination of a free layer, a barrier layer formed on the free layer, and a fixed layer formed on the barrier layer, wherein a sensing current flows substantially perpendicular to the magnetoresistive effect film, and wherein an amorphous material or a microcrystalline material is used in a lower shield.
    Type: Application
    Filed: May 14, 2001
    Publication date: January 24, 2002
    Inventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Eizo Fukami, Kiyokazu Nagahara, Hiroaki Honjo, Junichi Fujikata, Kunihiko Ishihara, Shigeru Mori
  • 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
  • Publication number: 20010053045
    Abstract: A recording head is a magnetic head in which ends on one side of opposed first and second magnetic cores form a recording gap, said other ends form a magnetic joint, coils insulated by an insulating material are provided between said first and second magnetic cores, magnetic fluxes of said first and second magnetic cores excited by said coils leak from said recording gap so that recording onto a recording medium is carried out. In said recording head, a distance from said end of said recording gap close to said magnetic medium to a contact point of said magnetic joint (hereinafter, yoke length) is not more than 20 &mgr;m. A magnetic recording/reproduction apparatus has this head.
    Type: Application
    Filed: December 27, 2000
    Publication date: December 20, 2001
    Inventors: Nobuyuki Ishiwata, Hiroaki Honjo, Tamaki Toba, Shinsaku Saito, Yoshihiro Nonaka, Tsutomu Ishi, Mikiko Saito, Keishi Ohashi
  • Patent number: 6267824
    Abstract: In a magnetoresistive effect composite head, magnetic shields oppose each other on a slider main body made of a ceramic material through a predetermined gap, and a magnetoresistive effect element is sandwiched and stacked between the magnetic shields with a magnetic spacer layer made of an insulator. A recording head portion uses one of the magnetic shields as a first magnetic pole, and has a second magnetic pole formed on a surface of the first magnetic pole opposite to the magnetoresistive effect element through a magnetic gap, to record information on a recording medium by means of a magnetic field generated in the magnetic gap. The magnetoresistive effect element includes a central region made of a spin-valve element to sense a medium field, and end regions for supplying a bias field and a current to the central region. The second magnetic pole is constituted by a stacked film of first and second magnetic films having different saturation magnetizations.
    Type: Grant
    Filed: May 19, 1999
    Date of Patent: July 31, 2001
    Assignee: NEC Corporation
    Inventors: Nobuyuki Ishiwata, Tsutomu Ishi, Kiyokazu Nagahara, Kazumasa Kumagai
  • 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
  • Patent number: 6154345
    Abstract: An ID head is formed after a MR head is formed. An upper shield far from a substrate is a first magnetic pole. A nonmagnetic insulator existing through a magnetic gap on the first magnetic pole determines zero throat height, thereby specifying a recording track width of less than 2 .mu.m. The ID head comprises a front end portion of a second magnetic pole, which is exposed to ABS and partly rides over the nonmagnetic insulator, a nonmagnetic insulator for burying a step by the front end portion, a coil which is formed on the nonmagnetic insulator and covered with a nonmagnetic insulator, and a main body portion of the second magnetic pole formed so as to ride over the coil and front end portion. As a result, it is possible to solved various problems of the ID head in which the front end portion of the second magnetic pole is formed first to realize a narrow track width.
    Type: Grant
    Filed: April 6, 1998
    Date of Patent: November 28, 2000
    Assignee: NEC Corporation
    Inventors: Nobuyuki Ishiwata, Kiyotaka Shimabayashi, Sinsaku Saitho, Hiroaki Tachibana, Tsutomu Ishi, Kiyokazu Nagahara, Kazumasa Kumagai
  • Patent number: 6141859
    Abstract: A merged head device which has: a slider main body with an air bearing surface to a magnetic medium; two magnetic shield films which are parallel disposed on a common plane with a predetermined interval and orthogonal to air flow on the downstream side of the air bearing surface of the slider main body; a magnetoresistive effect head which is disposed through a magnetic separating layer of an insulator between the two magnetic shield films; an inductive head which is composed of one magnetic pole film corresponding to one of the two magnetic shield films which is located downstream and the other magnetic pole film which is disposed through a magnetic gap on the other side of the one magnetic pole film where the magnetoresistive effect head does not exist, and recording is conducted by magnetic field which generates at the magnetic gap; and concave portions which are formed on both sides of the other magnetic pole film along the direction of the air flow on the air bearing surface of the slider main body so as
    Type: Grant
    Filed: June 29, 1999
    Date of Patent: November 7, 2000
    Assignee: NEC Corporation
    Inventors: Nobuyuki Ishiwata, Tsutomu Ishi, Kiyokazu Nagahara, Kazumasa Kumagai
  • Patent number: 6125009
    Abstract: In a magnetoresistive effect composite head, magnetic shields oppose each other on a slider main body made of a ceramic material through a predetermined gap, and a magnetoresistive effect element is sandwiched and stacked between the magnetic shields with a magnetic spacer layer made of an insulator. A recording head portion uses one of the magnetic shields as a first magnetic pole, and has a second magnetic pole formed on a surface of the first magnetic pole opposite to the magnetoresistive effect element through a magnetic gap, to record information on a recording medium by means of a magnetic field generated in the magnetic gap. The magnetoresistive effect element includes a central region made of a spin-valve element to sense a medium field, and end regions for supplying a bias field and a current to the central region. The second magnetic pole is constituted by a stacked film of first and second magnetic films having different saturation magnetizations.
    Type: Grant
    Filed: November 26, 1997
    Date of Patent: September 26, 2000
    Assignee: NEC Corporation
    Inventors: Nobuyuki Ishiwata, Tsutomu Ishi, Kiyokazu Nagahara, Kazumasa Kumagai
  • Patent number: 6057991
    Abstract: Disclosed is a merged head device which has: a slider main body with an air bearing surface to a magnetic medium; two magnetic shield films which are parallel disposed on a common plane with a predetermined interval and orthogonal to air flow on the downstream side of the air bearing surface of the slider main body; a magnetoresistive effect head which is disposed through a magnetic separating layer of an insulator between the two magnetic shield films; an inductive head which is composed of one magnetic pole film corresponding to one of the two magnetic shield films which is located downstream and the other magnetic pole film which is disposed through a magnetic gap on the other side of the one magnetic pole film where the magnetoresistive effect head does not exist, and recording is conducted by magnetic field which generates at the magnetic gap; and concave portions which are formed on both sides of the other magnetic pole film along the direction of the air flow on the air bearing surface of the slider ma
    Type: Grant
    Filed: November 26, 1997
    Date of Patent: May 2, 2000
    Assignee: NEC Corporation
    Inventors: Nobuyuki Ishiwata, Tsutomu Ishi, Kiyokazu Nagahara, Kazumasa Kumagai
  • Patent number: 6055137
    Abstract: A magnetoresistive effect composite head includes a read magnetoresistive effect (MR) head and a recording inductive (ID) head. The MR head has first and second magnetic shield films and an MR element. The first and second magnetic shield films are formed on a slider main body in a stacked manner through a predetermined gap therebetween. Each of the first and second magnetic shield films has an end face flush with a slider floating surface. The MR element is formed between the first and second magnetic shield films through magnetic isolation layers each made of an insulator. The ID head has a first magnetic pole film, a coil, and a second magnetic pole film. The first magnetic pole film serves also as the second magnetic shield film. The coil and the second magnetic pole film are formed through an insulator on the first magnetic pole film on a surface opposite to the MR element through a predetermined magnetic gap. The second magnetic pole film has a projecting portion that defines a track width.
    Type: Grant
    Filed: December 12, 1997
    Date of Patent: April 25, 2000
    Assignee: NEC Corporation
    Inventors: Nobuyuki Ishiwata, Tsutomu Ishi, Kiyokazu Nagahara, Kazumasa Kumagai