Patents by Inventor Tetsuhiro Suzuki
Tetsuhiro Suzuki 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: 7929342Abstract: The present invention provides a new data writing method for an MRAM which can suppress deterioration of a tunnel barrier layer. A magnetic memory cell 1 has a magnetic recording layer 10 and a pinned layer 30 connected to the magnetic recording layer 10 through a non-magnetic layer 20. The magnetic recording layer 10 includes a magnetization switching region 13, a first magnetization fixed region 11 and a second magnetization fixed region 12. The magnetization switching region 13 has reversible magnetization and faces the pinned layer 30. The first magnetization fixed region 11 is connected to a first boundary B1 of the magnetization switching region 13 and its magnetization direction is fixed to a first direction. The second magnetization fixed region 12 is connected to a second boundary B2 of the magnetization switching region 13 and its magnetization direction is fixed to a second direction.Type: GrantFiled: August 4, 2006Date of Patent: April 19, 2011Assignee: NEC CorporationInventors: Hideaki Numata, Norikazu Ohshima, Tetsuhiro Suzuki, Tadahiko Sugibayashi, Nobuyuki Ishiwata, Shunsuke Fukami
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Patent number: 7916520Abstract: A memory cell is used which includes a plurality of magneto-resistive elements and a plurality of laminated ferrimagnetic structure substances. The plurality of the magneto-resistive elements are placed corresponding to respective positions where a plurality of first wirings extended in a first direction intersects with a plurality of second wirings extended in a second direction which is substantially perpendicular to the first direction. The plurality of the laminated ferrimagnetic structure substances corresponds to the plurality of the magneto-resistive elements, respectively, is placed to have a distance of a predetermined range from the respective plurality of the magneto-resistive elements, and has a laminated ferrimagnetic structure. The magneto-resistive element includes a free layer having a laminated ferrimagnetic structure, a fixed layer, and a nonmagnetic layer interposed between the free layer and the fixed layer.Type: GrantFiled: August 19, 2005Date of Patent: March 29, 2011Assignee: NEC CorporationInventors: Tadahiko Sugibayashi, Takeshi Honda, Noboru Sakimura, Tetsuhiro Suzuki
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Patent number: 7894249Abstract: A magnetoresistive element includes a free layer a pinned layer; a nonmagnetic layer interposed between the free layer and the pinned layer; and two magnetic layers arranged adjacent to the free layer on an opposite side to the pinned layer. The free layer includes: a first magnetic layer, a second magnetic layer, and a first nonmagnetic layer interposed between the first magnetic layer and the second magnetic layer. Magnetization of the first magnetic layer and magnetization of the second magnetic layer are antiferromagnetically coupled. One of the two magnetic layers is in contact with one end of the free layer in a long-axis direction, and the other of the two magnetic layers is in contact with the other end of the free layer in the long-axis direction.Type: GrantFiled: February 23, 2007Date of Patent: February 22, 2011Assignee: NEC CorporationInventors: Ryusuke Nebashi, Tetsuhiro Suzuki
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Publication number: 20110002163Abstract: A semiconductor device includes: a first magnetic random access memory including a first memory cell and a second magnetic random access memory including a second memory cell operating at higher speed than the first memory cell and is provided on the same chip together with the first magnetic random access memory. The first memory cell is a current-induced domain wall motion type MRAM and stores data based on a domain wall position of a magnetization free layer. A layer that a write current flows is different from a layer that a read current flows. The second memory cell is a current-induced magnetic field writing type MRAM and stores data based on a magnetic field induced by a write current.Type: ApplicationFiled: March 5, 2009Publication date: January 6, 2011Inventors: Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Norikazu Ohshima, Kiyokazu Nagahara
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Publication number: 20100315854Abstract: A domain wall motion type MRAM has: a magnetic recording layer 10 having perpendicular magnetic anisotropy; and a pair of terminals 51 and 52 used for supplying a current to the magnetic recording layer 10. The magnetic recording layer 10 has: a first magnetization region 11 connected to one of the pair of terminals; a second magnetization region 12 connected to the other of the pair of terminals; and a magnetization switching region 13 connecting between the first magnetization region 11 and the second magnetization region 12 and having reversible magnetization. A first pinning site PS1, by which the domain wall is trapped, is formed at a boundary between the first magnetization region 11 and the magnetization switching region 13. A second pinning site PS2, by which the domain wall is trapped, is formed at a boundary between the second magnetization region 12 and the magnetization switching region 13.Type: ApplicationFiled: December 10, 2008Publication date: December 16, 2010Inventors: Tetsuhiro Suzuki, Shunsuke Fukami, Norikazu Ohshima, Kiyokazu Nagahara, Nobuyuki Ishiwata
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Publication number: 20100309713Abstract: An MRAM has: a memory cell including a first magnetoresistance element; and a reference cell including a second magnetoresistance element. The first magnetoresistance element has a first magnetization fixed layer, a first magnetization free layer, a first nonmagnetic layer sandwiched between the first magnetization fixed layer and the first magnetization free layer, a second magnetization fixed layer, a second magnetization free layer and a second nonmagnetic layer sandwiched between the second magnetization fixed layer and the second magnetization free layer. The first magnetization fixed layer and the first magnetization free layer have perpendicular magnetic anisotropy, and the second magnetization fixed layer and the second magnetization free layer have in-plane magnetic anisotropy. The first magnetization free layer and the second magnetization free layer are magnetically coupled to each other.Type: ApplicationFiled: January 9, 2009Publication date: December 9, 2010Inventors: Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Norikazu Ohshima, Kiyokazu Nagahara
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Publication number: 20100309712Abstract: An MRAM has: a memory cell including a first magnetoresistance element; and a reference cell including a second magnetoresistance element. The first magnetoresistance element has a first magnetization free layer, a first magnetization fixed layer, a second magnetization free layer and a first nonmagnetic layer sandwiched between the first magnetization fixed layer and the second magnetization free layer. The first magnetization free layer has perpendicular magnetic anisotropy, and the first magnetization fixed layer and the second magnetization free layer has in-plane magnetic anisotropy. The first magnetization free layer has: first and second magnetization fixed regions whose magnetization directions are fixed; and a magnetization free region whose magnetization direction is reversible and connected to the first and second magnetization fixed regions. The magnetization free region and the second magnetization free layer are magnetically coupled to each other.Type: ApplicationFiled: January 9, 2009Publication date: December 9, 2010Inventors: Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Norikazu Ohshima, Kiyokazu Nagahara
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Patent number: 7817462Abstract: MRAM includes a first wiring, a second wiring, and a memory cell. The first wiring extends to a first direction, and the second wiring extends to a second direction. The memory cell includes a free magnetic layer in which a plurality of magnetic layers coupled anti-ferromagnetically through non-magnetic layers are laminated, and is provided at an intersection of the first and second wirings. The magnetization direction of the free magnetic layer is different from the first and second directions. The writing method includes (a) reading a first data stored in the memory cell; (b) comparing a second data to be written to the memory cell and the first data; and (c) changing a direction of a first write current supplied to the first wiring and a direction of the second write current to be supplied to the second wiring, when the first data and second data are different.Type: GrantFiled: March 23, 2006Date of Patent: October 19, 2010Assignee: Nec CorporationInventors: Sadahiko Miura, Tadahiko Sugibayashi, Tetsuhiro Suzuki
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Publication number: 20100254183Abstract: A magnetoresistance effect element has: a first magnetization fixed layer whose magnetization direction is fixed; a first magnetization free layer whose magnetization direction is variable; a first nonmagnetic layer sandwiched between the first magnetization fixed layer and the first magnetization free layer; a second magnetization fixed layer whose magnetization direction is fixed; a second magnetization free layer whose magnetization direction is variable; and a second nonmagnetic layer sandwiched between the second magnetization fixed layer and the second magnetization free layer. The first magnetization fixed layer and the first magnetization free layer have perpendicular magnetic anisotropy, while the second magnetization fixed layer and the second magnetization free layer have in-plane magnetic anisotropy. The first magnetization free layer and the second magnetization free layer are magnetically coupled to each other.Type: ApplicationFiled: August 21, 2008Publication date: October 7, 2010Inventors: Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Norikazu Ohshima, Kiyokazu Nagahara
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Publication number: 20100237449Abstract: A magnetoresistive element is provided with a first magnetization free layer; a second magnetization free layer; a non-magnetic layer disposed adjacent to the second magnetization free layer; and a first magnetization fixed layer disposed adjacent to the second magnetization free layer on an opposite side of the second magnetization free layer. The first magnetization free layer is formed of ferromagnetic material and has a magnetic anisotropy in a thickness direction. On the other hand, the second magnetization free layer and the first magnetization fixed layer are formed of ferromagnetic material and have a magnetic anisotropy in an in-plane direction. The first magnetization free layer includes: a first magnetization fixed region having a fixed magnetization; a second magnetization fixed region having a fixed magnetization; and a magnetization free region connected to the first and second magnetization fixed regions and having a reversible magnetization.Type: ApplicationFiled: October 28, 2008Publication date: September 23, 2010Inventors: Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Kiyokazu Nagahara, Norikazu Ohshima
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Publication number: 20100214826Abstract: A magnetic random access memory includes: a first ferromagnetic layet; an insulating layer provided adjacent to the first ferromagnetic layer; and a first magnetization pinned layer provided adjacent to the insulating layer on a side opposite to the first ferromagnetic layer. The first ferromagnetic layer includes a magnetization free region, a first magnetization pinned region, and a second magnetization pinned region. The magnetization free region has reversible magnetization, and overlaps with the second ferromagnetic layer. The first magnetization pinned region has first pinned magnetization, and is connected to a part of the magnetization free region. The second magnetization pinned region has second pinned magnetization, and is connected to a part of the magnetization free region. The first ferromagnetic layer has magnetic anisotropy in a direction perpendicular to a film surface.Type: ApplicationFiled: July 7, 2008Publication date: August 26, 2010Applicant: NEC CORPORATIONInventors: Shunsuke Fukami, Tetsuhiro Suzuki, Kiyokazu Nagahara, Norikazu Ohshima, Nobuyuki Ishiwata
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Publication number: 20100193890Abstract: A magnetic random access memory includes: a magnetic recording layer including a ferromagnetic layer and having perpendicular magnetic anisotropy; and a magnetic reading layer provided on the magnetic recording layer and used for reading information. The magnetic recording layer includes: a magnetization switching area having reversible magnetization; a first magnetization pinned area connected to a first boundary of the magnetization switching area and having magnetization whose direction is pinned in a first direction; and a second magnetization pinned area connected to a second boundary of the magnetization switching area and having magnetization whose direction is pinned in a second direction. The magnetic reading layer includes: a magnetic sensing layer whose direction of magnetization changes based on a direction of the magnetization of the magnetization switching area; a nonmagnetic barrier layer provided on the magnetic sensing layer; and a pinned layer provided on the nonmagnetic barrier layer.Type: ApplicationFiled: July 7, 2008Publication date: August 5, 2010Inventors: Tetsuhiro Suzuki, Norikazu Ohshima, Shunsuke Fukami, Kiyokazu Nagahara, Nobuyuki Ishiwata
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Publication number: 20100193889Abstract: A domain wall motion type MRAM 100 has: a magnetic recording layer 10 that is a ferromagnetic layer; and a magnetic coupling layer 20 that is a ferromagnetic layer whose magnetization direction is fixed. The magnetic recording layer 10 has: a first region 10-1; a second region 10-2; and a magnetization switching region 10-3 connecting between the first region 10-1 and the second region 10-2. The first region 10-1 is magnetically coupled to the magnetic coupling layer 20 and its magnetization direction is fixed in a first direction by the magnetic coupling layer 20. The second region 10-2 is not magnetically coupled to the magnetic coupling layer 20 and its magnetization direction is a second direction that is opposite to the first direction.Type: ApplicationFiled: July 7, 2008Publication date: August 5, 2010Inventors: Kiyokazu Nagahara, Shunsuke Fukami, Tetsuhiro Suzuki, Norikazu Ohshima, Nobuyuki Ishiwata
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Publication number: 20100142264Abstract: The present invention provides a new data writing method for an MRAM which can suppress deterioration of a tunnel barrier layer. A magnetic memory cell 1 has a magnetic recording layer 10 and a pinned layer 30 connected to the magnetic recording layer 10 through a non-magnetic layer 20. The magnetic recording layer 10 includes a magnetization switching region 13, a first magnetization fixed region 11 and a second magnetization fixed region 12. The magnetization switching region 13 has reversible magnetization and faces the pinned layer 30. The first magnetization fixed region 11 is connected to a first boundary B1 of the magnetization switching region 13 and its magnetization direction is fixed to a first direction. The second magnetization fixed region 12 is connected to a second boundary B2 of the magnetization switching region 13 and its magnetization direction is fixed to a second direction.Type: ApplicationFiled: August 4, 2006Publication date: June 10, 2010Applicant: NEC CORPORATIONInventors: Hideaki Numata, Norikazu Ohshima, Tetsuhiro Suzuki, Tadahiko Sugibayashi, Nobuyuki Ishiwata, Shunsuke Fukami
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Publication number: 20100096715Abstract: A magnetic recording layer 10 of an MRAM has a first magnetization fixed region 11, a second magnetization fixed region 12 and a magnetization switching region 13. The magnetization switching region 13 has reversible magnetization and overlaps with a pinned layer. The first magnetization fixed region 11 is connected to a first boundary B1 of the magnetization switching region 13 and its magnetization direction is fixed to a first direction. The second magnetization fixed region 12 is connected to a second boundary B2 of the magnetization switching region 13 and its magnetization direction is fixed to a second direction. Both of the first direction and the second direction are toward the magnetization switching region 13 or away from the magnetization switching region 13. The damping coefficient ? in at least a portion R1, R2 of the magnetization fixed regions 11 and 12 is larger than the damping coefficient ? in the magnetization switching region 13.Type: ApplicationFiled: January 15, 2008Publication date: April 22, 2010Inventors: Tetsuhiro Suzuki, Norikazu Ohshima, Hideaki Numata
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Publication number: 20100046288Abstract: An MRAM according to the present invention has a pinned layer 60 and a magnetic recording layer 40 connected to the pinned layer 60 through a tunnel barrier layer 50. The magnetic recording layer 40 has a first free layer 10, a second free layer 30 being in contact with the tunnel barrier layer 50, and an intermediate layer 20 provided between the first free layer 10 and the second free layer 30. The first free layer 10 includes a magnetization switching region 13, a first magnetization fixed region 11 and a second magnetization fixed region 12. The magnetization switching region 13 has reversible magnetization and overlaps the second free layer 30. The first magnetization fixed region 11 is connected to a first boundary B1 of the magnetization switching region 13 and its magnetization orientation is fixed in a first direction.Type: ApplicationFiled: October 22, 2007Publication date: February 25, 2010Inventors: Hiroaki Honjou, Tetsuhiro Suzuki, Norikazu Ohshima
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Patent number: 7582923Abstract: The present invention to provide a new technique to reduce a variation in switching field of a magnetization free layer in a magnetic memory. The magnetic memory according to the present invention includes a magnetization free layer including a ferromagnetic layer having a shape magnetic anisotropy in a first direction and a magnetic strain constant is positive; and a stress inducing structure configured to apply a tensile stress to said magnetization free layer in a same direction as the first direction.Type: GrantFiled: November 16, 2005Date of Patent: September 1, 2009Assignee: NEC CorporationInventors: Yoshiyuki Fukumoto, Tetsuhiro Suzuki, Katsumi Suemitsu
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Publication number: 20090141540Abstract: MRAM includes a first wiring, a second wiring, and a memory cell. The first wiring extends to a first direction, and the second wiring extends to a second direction. The memory cell includes a free magnetic layer in which a plurality of magnetic layers coupled anti-ferromagnetically through non-magnetic layers are laminated, and is provided at an intersection of the first and second wirings. The magnetization direction of the free magnetic layer is different from the first and second directions. The writing method includes (a) reading a first data stored in the memory cell; (b) comparing a second data to be written to the memory cell and the first data; and (c) changing a direction of a first write current supplied to the first wiring and a direction of the second write current to be supplied to the second wiring, when the first data and second data are different.Type: ApplicationFiled: March 23, 2006Publication date: June 4, 2009Applicant: NEC CORPORATIONInventors: Sadahiko Miura, Tadahiko Sugibayashi, Tetsuhiro Suzuki
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Publication number: 20090135644Abstract: A magnetoresistive element includes a free layer a pinned layer; a nonmagnetic layer interposed between the free layer and the pinned layer; and two magnetic layers arranged adjacent to the free layer on an opposite side to the pinned layer. The free layer includes: a first magnetic layer, a second magnetic layer, and a first nonmagnetic layer interposed between the first magnetic layer and the second magnetic layer. Magnetization of the first magnetic layer and magnetization of the second magnetic layer are antiferromagnetically coupled. One of the two magnetic layers is in contact with one end of the free layer in a long-axis direction, and the other of the two magnetic layers is in contact with the other end of the free layer in the long-axis direction.Type: ApplicationFiled: February 23, 2007Publication date: May 28, 2009Applicant: NEC CORPORATIONInventors: Ryusuke Nebashi, Tetsuhiro Suzuki
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Publication number: 20080164502Abstract: The present invention to provide a new technique to reduce a variation in switching field of a magnetization free layer in a magnetic memory. The magnetic memory according to the present invention includes a magnetization free layer including a ferromagnetic layer having a shape magnetic anisotropy in a first direction and a magnetic strain constant is positive; and a stress inducing structure configured to apply a tensile stress to said magnetization free layer in a same direction as the first direction.Type: ApplicationFiled: November 16, 2005Publication date: July 10, 2008Applicant: NEC CORPORATIONInventors: Yoshiyuki Fukumoto, Tetsuhiro Suzuki, Katsumi Suemitsu