Patents by Inventor Kenchi Ito
Kenchi Ito 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: 11054463Abstract: A method and a system for measuring the thermal stability factor of a magnetic tunnel junction device, a semiconductor integrated circuit, and a production management method for the semiconductor integrated circuit, capable of measuring the thermal stability factors of individual devices in a relatively short period of time and quickly performing quality control during material development and at a production site. A meter measures change in resistance value of an evaluation MTJ for a predetermined period while causing a predetermined current to flow into the evaluation MTJ maintained at a predetermined temperature. An analyzer calculates a time constant in which a low-resistance state is maintained and a time constant in which a high-resistance state is maintained from the measured change in resistance value. A thermal stability factor of the evaluation MTJ is calculated on the basis of the calculated time constants and the predetermined current flowing into the evaluation MTJ.Type: GrantFiled: March 22, 2017Date of Patent: July 6, 2021Assignee: TOHOKU UNIVERSITYInventors: Kenchi Ito, Tetsuo Endoh, Hideo Sato, Takashi Saito, Masakazu Muraguchi, Hideo Ohno
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Patent number: 10658572Abstract: A magnetoresistance effect element includes first and second magnetic layers having a perpendicular magnetization direction, and a first non-magnetic layer disposed adjacent to the first magnetic layer and on a side opposite to a side on which the second magnetic layer is disposed. An interfacial perpendicular magnetic anisotropy exists at an interface between the first magnetic layer and the first non-magnetic layer, and the anisotropy causes the first magnetic layer to have a magnetization direction perpendicular to the surface of the layers. An atomic fraction of all magnetic elements to all magnetic and non-magnetic elements included in the second magnetic layer is smaller than that of the first magnetic layer.Type: GrantFiled: November 2, 2018Date of Patent: May 19, 2020Assignee: TOHOKU UNIVERSITYInventors: Hideo Sato, Shoji Ikeda, Mathias Bersweiler, Hiroaki Honjo, Kyota Watanabe, Shunsuke Fukami, Fumihiro Matsukura, Kenchi Ito, Masaaki Niwa, Tetsuo Endoh, Hideo Ohno
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Patent number: 10644234Abstract: A method for producing a magnetic memory includes: forming a magnetic film having a non-magnetic layer between a first magnetic layer and a second magnetic layer on a substrate having an electrode layer; performing annealing treatment at a first treatment temperature in a state where a magnetic field is applied in a direction perpendicular to a film surface of the first or the second magnetic layer in vacuum; forming a magnetic tunnel junction element; forming a protective film protecting the magnetic tunnel junction element; a formation accompanied by thermal history, in which a constituent element of a magnetic memory is formed after the protective film formation on the substrate; and implementing annealing treatment at a second treatment temperature lower than the first treatment temperature on the substrate in an annealing treatment chamber, in vacuum or inert gas wherein no magnetic field is applied.Type: GrantFiled: August 28, 2017Date of Patent: May 5, 2020Assignee: TOHOKU UNIVERSITYInventors: Kenchi Ito, Tetsuo Endoh, Shoji Ikeda, Hideo Sato, Hideo Ohno, Sadahiko Miura, Masaaki Niwa, Hiroaki Honjo
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Publication number: 20190219633Abstract: A method and a system for measuring the thermal stability factor of a magnetic tunnel junction device, a semiconductor integrated circuit, and a production management method for the semiconductor integrated circuit, capable of measuring the thermal stability factors of individual devices in a relatively short period of time and quickly performing quality control during material development and at a production site. A meter measures change in resistance value of an evaluation MTJ for a predetermined period while causing a predetermined current to flow into the evaluation MTJ maintained at a predetermined temperature. An analyzer calculates a time constant in which a low-resistance state is maintained and a time constant in which a high-resistance state is maintained from the measured change in resistance value. A thermal stability factor of the evaluation MTJ is calculated on the basis of the calculated time constants and the predetermined current flowing into the evaluation MTJ.Type: ApplicationFiled: March 22, 2017Publication date: July 18, 2019Applicant: TOHOKU UNIVERSITYInventors: Kenchi ITO, Tetsuo ENDOH, Hideo SATO, Takashi SAITO, Masakazu MURAGUCHI, Hideo OHNO
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Publication number: 20190198755Abstract: A method for producing a magnetic memory includes: forming a magnetic film having a non-magnetic layer between a first magnetic layer and a second magnetic layer on a substrate having an electrode layer; performing annealing treatment at a first treatment temperature in a state where a magnetic field is applied in a direction perpendicular to a film surface of the first or the second magnetic layer in vacuum; forming a magnetic tunnel junction element; forming a protective film protecting the magnetic tunnel junction element; a formation accompanied by thermal history, in which a constituent element of a magnetic memory is formed after the protective film formation on the substrate; and implementing annealing treatment at a second treatment temperature lower than the first treatment temperature on the substrate in an annealing treatment chamber, in vacuum or inert gas wherein no magnetic field is applied.Type: ApplicationFiled: August 28, 2017Publication date: June 27, 2019Inventors: Kenchi ITO, Tetsuo ENDOH, Shoji IKEDA, Hideo SATO, Hideo OHNO, Sadahiko MIURA, Masaaki NIWA, Hiroaki HONJO
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Publication number: 20190074433Abstract: A magnetoresistance effect element includes first and second magnetic layers having a perpendicular magnetization direction, and a first non-magnetic layer disposed adjacent to the first magnetic layer and on a side opposite to a side on which the second magnetic layer is disposed. An interfacial perpendicular magnetic anisotropy exists at an interface between the first magnetic layer and the first non-magnetic layer, and the anisotropy causes the first magnetic layer to have a magnetization direction perpendicular to the surface of the layers. An atomic fraction of all magnetic elements to all magnetic and non-magnetic elements included in the second magnetic layer is smaller than that of the first magnetic layer.Type: ApplicationFiled: November 2, 2018Publication date: March 7, 2019Applicant: TOHOKU UNIVERSITYInventors: Hideo SATO, Shoji IKEDA, Mathias BERSWEILER, Hiroaki HONJO, Kyota WATANABE, Shunsuke FUKAMI, Fumihiro MATSUKURA, Kenchi ITO, Masaaki NIWA, Tetsuo ENDOH, Hideo OHNO
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Patent number: 10164174Abstract: A magnetoresistance effect element includes first and second magnetic layers having a perpendicular magnetization direction, and a first non-magnetic layer disposed adjacent to the first magnetic layer and on a side opposite to a side on which the second magnetic layer is disposed. An interfacial perpendicular magnetic anisotropy exists at an interface between the first magnetic layer and the first non-magnetic layer, and the anisotropy causes the first magnetic layer to have a magnetization direction perpendicular to the surface if the layers. The second magnetic layer has a saturation magnetization lower than that of the first magnetic layer, and an interfacial magnetic anisotropy energy density (Ki) at the interface between the first magnetic layer and the first non-magnetic layer is greater than that of an interface between the first non-magnetic layer and second magnetic layers if being disposed adjacent each other.Type: GrantFiled: January 16, 2018Date of Patent: December 25, 2018Assignee: TOHOKU UNIVERSITYInventors: Hideo Sato, Shoji Ikeda, Mathias Bersweiler, Hiroaki Honjo, Kyota Watanabe, Shunsuke Fukami, Fumihiro Matsukura, Kenchi Ito, Masaaki Niwa, Tetsuo Endoh, Hideo Ohno
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Publication number: 20180175286Abstract: A magnetoresistance effect element includes first and second magnetic layers having a perpendicular magnetization direction, and a first non-magnetic layer disposed adjacent to the first magnetic layer and on a side opposite to a side on which the second magnetic layer is disposed. An interfacial perpendicular magnetic anisotropy exists at an interface between the first magnetic layer and the first non-magnetic layer, and the anisotropy causes the first magnetic layer to have a magnetization direction perpendicular to the surface if the layers. The second magnetic layer has a saturation magnetization lower than that of the first magnetic layer, and an interfacial magnetic anisotropy energy density (Ki) at the interface between the first magnetic layer and the first non-magnetic layer is greater than that of an interface between the first non-magnetic layer and second magnetic layers if being disposed adjacent each other.Type: ApplicationFiled: January 16, 2018Publication date: June 21, 2018Applicant: TOHOKU UNIVERSITYInventors: Hideo SATO, Shoji IKEDA, Mathias BERSWEILER, Hiroaki HONJO, Kyota WATANABE, Shunsuke FUKAMI, Fumihiro MATSUKURA, Kenchi ITO, Masaaki NIWA, Tetsuo ENDOH, Hideo OHNO
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Patent number: 9602103Abstract: As a technique for attaining a reduction in power consumption, there is a technique for reducing power consumption using a spin wave. No specific proposal concerning spin wave generation, spin wave detection, and a latch technique for information has been made. A device applies an electric field to a first electrode of a nonmagnetic material using a thin line-shaped stacked body including a first ferromagnetic layer and a nonmagnetic layer to thereby generate a spin wave in the first ferromagnetic layer, and detects a phase or amplitude of the spin wave propagated in the first ferromagnetic layer using a second electrode of a ferromagnetic material with a magnetoresistance effect.Type: GrantFiled: May 22, 2013Date of Patent: March 21, 2017Assignee: Hitachi, Ltd.Inventors: Katsuya Miura, Susumu Ogawa, Kenchi Ito, Masaki Yamada
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Publication number: 20160105176Abstract: As a technique for attaining a reduction in power consumption, there is a technique for reducing power consumption using a spin wave. No specific proposal concerning spin wave generation, spin wave detection, and a latch technique for information has been made. A device applies an electric field to a first electrode of a nonmagnetic material using a thin line-shaped stacked body including a first ferromagnetic layer and a nonmagnetic layer to thereby generate a spin wave in the first ferromagnetic layer, and detects a phase or amplitude of the spin wave propagated in the first ferromagnetic layer using a second electrode of a ferromagnetic material with a magnetoresistance effect.Type: ApplicationFiled: May 22, 2013Publication date: April 14, 2016Inventors: Katsuya MIURA, Susumu OGAWA, Kenchi ITO, Masaki YAMADA
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Patent number: 9257483Abstract: There is provided a magnetic memory with using a magnetoresistive effect element of a spin-injection magnetization reversal type, in which a multi-value operation is possible and whose manufacturing and operation are simple. A preferred aim of this is solved by providing two or more magnetoresistive effect elements which are electrically connected in series to each other and by selecting one of the series-connected elements depending on a direction of a current carried in the series-connected elements, a magnitude thereof, and an order of the current thereof for performing the writing operation. For example, it is solved by differentiating plane area sizes of the respective magnetoresistive effect elements which have the same film structure from each other so as to differentiate resistance change amounts caused by respective magnetization reversal and threshold current values required for respective magnetization reversal from each other.Type: GrantFiled: January 13, 2011Date of Patent: February 9, 2016Assignee: Hitachi, Ltd.Inventors: Takashi Ishigaki, Takayuki Kawahara, Riichiro Takemura, Kazuo Ono, Kenchi Ito
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Patent number: 9042165Abstract: A magnetoresistive effect element uses a perpendicularly magnetized material and has a high TMR ratio. Intermediate layers composed of an element metal having a melting point of 1600° C. or an alloy containing the metal on an outside of a structure consisting of a CoFeB layer, an MgO barrier layer, and a CoFeB layer. By inserting the intermediate layers, crystallization of the CoFeB layer during annealing is advanced from an MgO (001) crystal side, so that the CoFeB layer has a crystalline orientation in bcc (001).Type: GrantFiled: January 25, 2011Date of Patent: May 26, 2015Assignees: Hitachi, Ltd., Tohoku UniversityInventors: Shoji Ikeda, Hideo Ohno, Hiroyuki Yamamoto, Kenchi Ito, Hiromasa Takahashi
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Patent number: 9000546Abstract: A spin-wave waveguide includes a ferromagnetic thin film resembling a wire in shape. A part of the ferromagnetic thin film, large in film thickness, is formed at one end of the ferromagnetic thin film, and a part of the ferromagnetic thin film, small in film thickness, and a part of the ferromagnetic thin film, large in film thickness, are alternately formed on the same plane, for at least not less than one cycle. A part of the ferromagnetic thin film, large in film thickness, is formed at the other end of the ferromagnetic thin film, wherein an insulating film, and an electrode film are stacked in this order on the ferromagnetic thin film in the part of the ferromagnetic thin film, large in film thickness.Type: GrantFiled: December 4, 2012Date of Patent: April 7, 2015Assignee: Hitachi, Ltd.Inventors: Kenchi Ito, Masaki Yamada, Susumu Ogawa
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Patent number: 8957486Abstract: Provided is a magnetic random access memory to which spin torque magnetization reversal is applied, the magnetic random access memory being thermal stable in a reading operation and also being capable of reducing a current in a wiring operation. A magnetoresistive effect element formed by sequentially stacking a fixed layer, a nonmagnetic barrier layer, and a recording layer is used as a memory element. The recording layer adopts a laminated ferrimagnetic structure.Type: GrantFiled: March 4, 2009Date of Patent: February 17, 2015Assignee: Hitachi, Ltd.Inventors: Kenchi Ito, Jun Hayakawa, Katsuya Miura, Hiroyuki Yamamoto
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Publication number: 20130107616Abstract: A magnetoresistive effect element is provided that exhibits a low writing current density while maintaining a high TMR ratio. A laminated structure of a second ferromagnetic layer/a non-magnetic layer/a first ferromagnetic layer is employed as a recording layer. A material of bcc crystalline structure, such as CoFeB, is employed as a second ferromagnetic layer being in contact with MgO barrier layer. A material whose anisotropy field Hk? in the perpendicular direction is large and that satisfies the relationship of 2?rMs<Hk?<4?Ms is employed as a first ferromagnetic layer. Although a magnetic easy axis of the first ferromagnetic layer lies in-plane, it has a high perpendicular anisotropy field of half or more of the demagnetizing field in the perpendicular direction. Therefore, the effective demagnetizing field in the perpendicular direction is reduced, and a writing current density can be reduced.Type: ApplicationFiled: July 9, 2010Publication date: May 2, 2013Inventors: Hideo Ohno, Shoji Ikeda, Hiroyuki Yamamoto, Kenchi Ito, Hiromasa Takahashi
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Patent number: 8427864Abstract: To write information on a memory cell of SPRAM formed of an MOS transistor and a tunnel magnetoresistive element, the memory cell is supplied with a current in a direction opposite to a direction of a current required for writing the information on the memory cell, and then, the memory cell is supplied with a current required for writing. In this manner, even when the same information is sequentially written on the memory cell, since the currents in the two directions are caused to flow in pairs in the tunnel magnetoresistive element of the memory cell each time information is rewritten, deterioration of a film that forms the tunnel magnetoresistive element can be suppressed. Therefore, reliability of the SPRAM can be improved.Type: GrantFiled: June 2, 2010Date of Patent: April 23, 2013Assignee: Hitachi, Ltd.Inventors: Takayuki Kawahara, Kiyoo Itoh, Riichiro Takemura, Kenchi Ito
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Publication number: 20130044537Abstract: There is provided a magnetic memory with using a magnetoresistive effect element of a spin-injection magnetization reversal type, in which a multi-value operation is possible and whose manufacturing and operation are simple. A preferred aim of this is solved by providing two or more magnetoresistive effect elements which are electrically connected in series to each other and by selecting one of the series-connected elements depending on a direction of a current carried in the series-connected elements, a magnitude thereof, and an order of the current thereof for performing the writing operation. For example, it is solved by differentiating plane area sizes of the respective magnetoresistive effect elements which have the same film structure from each other so as to differentiate resistance change amounts caused by respective magnetization reversal and threshold current values required for respective magnetization reversal from each other.Type: ApplicationFiled: January 13, 2011Publication date: February 21, 2013Inventors: Takashi Ishigaki, Takayuki Kawahara, Riichiro Takemura, Kazuo Ono, Kenchi Ito
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Publication number: 20130028013Abstract: Provided is a magnetoresistive effect element which uses a perpendicularly magnetized material and has a high TMR ratio. Intermediate layers 31, 32 composed of an element metal having a melting point of 1600° C. or an alloy containing the metal on an outside of a structure consisting of a CoFeB layer 41, an MgO barrier layer 10, and a CoFeB layer 42. By inserting the intermediate layers 31, 32, crystallization of the CoFeB layer during annealing is advanced from an MgO (001) crystal side, so that the CoFeB layer has a crystalline orientation in bcc (001).Type: ApplicationFiled: January 25, 2011Publication date: January 31, 2013Inventors: Shoji Ikeda, Hideo Ohno, Hiroyuki Yamamoto, Kenchi Ito, Hiromasa Takahashi
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Publication number: 20120081952Abstract: To write information on a memory cell of SPRAM formed of an MOS transistor and a tunnel magnetoresistive element, the memory cell is supplied with a current in a direction opposite to a direction of a current required for writing the information on the memory cell, and then, the memory cell is supplied with a current required for writing. In this manner, even when the same information is sequentially written on the memory cell, since the currents in the two directions are caused to flow in pairs in the tunnel magnetoresistive element of the memory cell each time information is rewritten, deterioration of a film that forms the tunnel magnetoresistive element can be suppressed. Therefore, reliability of the SPRAM can be improved.Type: ApplicationFiled: June 2, 2010Publication date: April 5, 2012Inventors: Takayuki Kawahara, Kiyoo Itoh, Riichiro Takemura, Kenchi Ito
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Publication number: 20120012955Abstract: Provided is a magnetic random access memory to which spin torque magnetization reversal is applied, the magnetic random access memory being thermal stable in a reading operation and also being capable of reducing a current in a wiring operation. A magnetoresistive effect element formed by sequentially stacking a fixed layer, a nonmagnetic barrier layer, and a recording layer is used as a memory element. The recording layer adopts a laminated ferrimagnetic structure.Type: ApplicationFiled: March 4, 2009Publication date: January 19, 2012Applicant: HITACHI, LTD.Inventors: Kenchi Ito, Jun Hayakawa, Katsuya Miura, Hiroyuki Yamamoto