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).
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Patent number: 6751074Abstract: 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: GrantFiled: May 23, 2003Date of Patent: June 15, 2004Assignee: Kabushiki Kaisha ToshibaInventors: Koichiro Inomata, Kentaro Nakajima, Yoshiaki Saito, Masayuki Sagoi, Tatsuya Kishi
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Publication number: 20040100818Abstract: 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: ApplicationFiled: March 6, 2003Publication date: May 27, 2004Inventors: Hiroaki Yoda, Yoshiaki Asao, Tomomasa Ueda, Junichi Miyamoto, Tatsuya Kishi, Minoru Amano, Takeshi Kajiyama, Hisanori Aikawa
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Publication number: 20040085681Abstract: 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: ApplicationFiled: October 22, 2003Publication date: May 6, 2004Inventors: Tadashi Kai, Toshihiko Nagase, Tatsuya Kishi, Yoshiaki Saito
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Patent number: 6730949Abstract: 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: GrantFiled: March 22, 2002Date of Patent: May 4, 2004Assignee: Kabushiki Kaisha ToshibaInventors: Tatsuya Kishi, Minoru Amano, Yoshiaki Saito, Shigeki Takahashi, Kentaro Nakajima, Masayuki Sagoi
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Publication number: 20040076035Abstract: 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: ApplicationFiled: September 16, 2003Publication date: April 22, 2004Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Yoshiaki Saito, Tomomasa Ueda, Tatsuya Kishi, Minoru Amano
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Patent number: 6717845Abstract: 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: GrantFiled: January 16, 2003Date of Patent: April 6, 2004Assignee: Kabushiki Kaisha ToshibaInventors: Yoshiaki Saito, Katsuya Nishiyama, Shigeki Takahashi, Minoru Amano, Tomomasa Ueda, Hiroaki Yoda, Yoshiaki Asao, Yoshihisa Iwata, Tatsuya Kishi
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Publication number: 20040062938Abstract: 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: ApplicationFiled: September 3, 2003Publication date: April 1, 2004Applicant: Kabushiki Kaisha ToshibaInventors: Tadashi Kai, Shigeki Takahashi, Tomosasa Ueda, Tatsuya Kishi, Yoshiaki Saito
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Patent number: 6707711Abstract: 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: GrantFiled: February 4, 2003Date of Patent: March 16, 2004Assignee: Kabushiki Kaisha ToshibaInventors: Yoshiaki Saito, Koichiro Inomata, Minoru Amano, Kentaro Nakajima, Masayuki Sagoi, Tatsuya Kishi, Shigeki Takahashi
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Publication number: 20040021189Abstract: 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: ApplicationFiled: March 6, 2003Publication date: February 5, 2004Inventors: Hiroaki Yoda, Yoshiaki Asao, Tomomasa Ueda, Minoru Amano, Tatsuya Kishi, Keiji Hosotani, Junichi Miyamoto
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Publication number: 20040004889Abstract: 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: ApplicationFiled: April 18, 2003Publication date: January 8, 2004Inventors: Yoshiaki Asao, Yoshihisa Iwata, Yoshiaki Saito, Hiroaki Yoda, Tomomasa Ueda, Minoru Amano, Shigeki Takahashi, Tatsuya Kishi
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Publication number: 20030214862Abstract: 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: ApplicationFiled: April 22, 2003Publication date: November 20, 2003Inventors: Yoshiaki Asao, Yoshihisa Iwata, Yoshiaki Saito, Hiroaki Yoda, Tomomasa Ueda, Minoru Amano, Shigeki Takahashi, Tatsuya Kishi
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Publication number: 20030197984Abstract: 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: ApplicationFiled: May 23, 2003Publication date: October 23, 2003Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Koichiro Inomata, Kentaro Nakajima, Yoshiaki Saito, Masayuki Sagoi, Tatsuya Kishi
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Publication number: 20030185050Abstract: 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: ApplicationFiled: March 19, 2003Publication date: October 2, 2003Inventors: Tatsuya Kishi, Yoshiaki Saito, Minoru Amano, Shigeki Takahashi, Katsuya Nishiyama, Tomomasa Ueda
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Publication number: 20030186552Abstract: 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: ApplicationFiled: March 26, 2003Publication date: October 2, 2003Applicant: Kabushiki Kaisha ToshibaInventors: Minoru Amano, Tatsuya Kishi, Yoshiaki Saito, Tomomasa Ueda, Hiroaki Yoda
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Publication number: 20030161181Abstract: 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: ApplicationFiled: January 16, 2003Publication date: August 28, 2003Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Yoshiaki Saito, Katsuya Nishiyama, Shigeki Takahashi, Minoru Amano, Tomomasa Ueda, Hiroaki Yoda, Yoshiaki Asao, Yoshihisa Iwata, Tatsuya Kishi
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Patent number: 6611405Abstract: 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: GrantFiled: September 14, 2000Date of Patent: August 26, 2003Assignee: Kabushiki Kaisha ToshibaInventors: Koichiro Inomata, Kentaro Nakajima, Yoshiaki Saito, Masayuki Sagoi, Tatsuya Kishi
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Publication number: 20030156476Abstract: 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: ApplicationFiled: January 16, 2003Publication date: August 21, 2003Applicant: Kabushiki Kaisha ToshibaInventors: Tatsuya Kishi, Minoru Amano, Yoshiaki Saito, Shigeki Takahashi, Katsuya Nishiyama, Yoshiaki Asao, Hiroaki Yoda, Tomomasa Ueda, Yoshihisa Iwata
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Patent number: 6605836Abstract: 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: GrantFiled: March 15, 2002Date of Patent: August 12, 2003Assignee: Kabushiki Kaisha ToshibaInventors: Tatsuya Kishi, Shigeki Takahashi, Kentaro Nakajima, Minoru Amano, Masayuki Sagoi, Yoshiaki Saito
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Publication number: 20030137028Abstract: 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: ApplicationFiled: July 22, 2002Publication date: July 24, 2003Inventors: Keiji Hosotani, Yoshiaki Asao, Yoshiaki Saito, Minoru Amono, Shigeki Takahashi, Tatsuya Kishi, Yoshihisa Iwata
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Publication number: 20030137870Abstract: 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: ApplicationFiled: February 4, 2003Publication date: July 24, 2003Inventors: Yoshiaki Saito, Koichiro Inomata, Minoru Amano, Kentaro Nakajima, Masayuki Sagoi, Tatsuya Kishi, Shigeki Takahashi