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).
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Patent number: 7372673Abstract: 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: GrantFiled: May 31, 2005Date of Patent: May 13, 2008Assignee: NEC CorporationInventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Tsutomu Ishi, Hiroaki Honjou, Kunihiko Ishihara, Jun-Ichi Fujikata, Hisao Matsutera, Hisanao Tsuge, Atsushi Kamijo
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Patent number: 7126201Abstract: 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: GrantFiled: July 3, 2003Date of Patent: October 24, 2006Assignee: NEC CorporationInventors: Hisao Matsutera, Hideaki Numata
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Patent number: 7099184Abstract: 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: GrantFiled: July 28, 2003Date of Patent: August 29, 2006Assignee: NEC CorporationInventors: Tadahiko Sugibayashi, Takeshi Honda, Noboru Sakimura, Hisao Matsutera, Atsushi Kamijo, Kenichi Shimura, Kaoru Mori
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Patent number: 7068536Abstract: 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: GrantFiled: October 23, 2003Date of Patent: June 27, 2006Assignee: NEC CorporationInventors: Hisao Matsutera, Tetsuhiro Suzuki
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Publication number: 20060098477Abstract: 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: ApplicationFiled: July 28, 2003Publication date: May 11, 2006Inventors: Tadahiko Sugibayashi, Takeshi Honda, Noboru Sakimura, Hisao Matsutera, Atsushi Kamijo, Kenichi Shimura
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Publication number: 20050242407Abstract: 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: ApplicationFiled: July 3, 2003Publication date: November 3, 2005Inventors: Hisao Matsutera, Hideaki Numata
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Publication number: 20050219772Abstract: 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: ApplicationFiled: May 31, 2005Publication date: October 6, 2005Applicant: NEC CorporationInventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Tsutomu Ishi, Hiroaki Honjou, Kunihiko Ishihara, Jun-Ichi Fujikata, Hisao Matsutera, Hisanao Tsuge, Atsushi Kamijo
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Patent number: 6950290Abstract: 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: GrantFiled: September 12, 2002Date of Patent: September 27, 2005Assignee: NEC CorporationInventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Tsutomu Ishi, Hiroaki Honjou, Kunihiko Ishihara, Jun-Ichi Fujikata, Hisao Matsutera, Hisanao Tsuge, Atsushi Kamijo
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Publication number: 20050002229Abstract: 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: ApplicationFiled: October 23, 2003Publication date: January 6, 2005Inventors: Hisao Matsutera, Tetsuhiro Suzuki
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Patent number: 6639766Abstract: 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: GrantFiled: October 24, 2001Date of Patent: October 28, 2003Assignee: NEC CorporationInventors: Ishiwata Nobuyuki, Hisanao Tsuge, Hisao Matsutera, Yuji Tsukamoto, Masafumi Nakada, Atsushi Kamijo
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Patent number: 6542342Abstract: 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: GrantFiled: November 29, 1999Date of Patent: April 1, 2003Assignee: NEC CorporationInventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Tsutomu Ishi, Hiroaki Honjou, Kunihiko Ishihara, Jun-Ichi Fujikata, Hisao Matsutera, Hisanao Tsuge, Atsushi Kamijo
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Publication number: 20030035256Abstract: 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: ApplicationFiled: September 12, 2002Publication date: February 20, 2003Applicant: NEC CorporationInventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Tsutomu Ishi, Hiroaki Honjou, Kunihiko Ishihara, Jun-Ichi Fujikata, Hisao Matsutera, Hisanao Tsuge, Atsushi Kamijo
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Patent number: 6490139Abstract: 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: GrantFiled: January 27, 2000Date of Patent: December 3, 2002Assignee: NEC CorporationInventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Hisao Matsutera, Hisanao Tsuge, Atsushi Kamijo
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Publication number: 20020027753Abstract: 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: ApplicationFiled: October 24, 2001Publication date: March 7, 2002Applicant: NEC CorporationInventors: Nobuyuki Ishiwata, Hisanao Tsuge, Hisao Matsutera, Yuji Tsukamoto, Masafumi Nakada, Atsushi Kamijo
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Patent number: 6341053Abstract: 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: GrantFiled: October 30, 1998Date of Patent: January 22, 2002Assignee: NEC CorporationInventors: Masafumi Nakada, Hisanao Tsuge, Yuji Tsukamoto, Hisao Matsutera, Nobuyuki Ishiwata, Atsushi Kamijo
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Patent number: 6333842Abstract: The present invention provides a magneto-resistance effect (hereinafter, referred to as MR) type composite head.Type: GrantFiled: December 3, 1998Date of Patent: December 25, 2001Assignee: NEC CorporationInventors: Ishiwata Nobuyuki, Hisanao Tsuge, Hisao Matsutera, Yuji Tsukamoto, Masafumi Nakada, Atsushi Kamijo
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Patent number: 6174736Abstract: 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: GrantFiled: December 11, 1998Date of Patent: January 16, 2001Assignee: NEC CorporationInventors: Yuji Tsukamoto, Hisanao Tsuge, Nobuyuki Ishiwata, Hisao Matsutera, Masafumi Nakada, Atsushi Kamijo