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).

  • Patent number: 10658572
    Abstract: 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: Grant
    Filed: November 2, 2018
    Date of Patent: May 19, 2020
    Assignee: TOHOKU UNIVERSITY
    Inventors: Hideo Sato, Shoji Ikeda, Mathias Bersweiler, Hiroaki Honjo, Kyota Watanabe, Shunsuke Fukami, Fumihiro Matsukura, Kenchi Ito, Masaaki Niwa, Tetsuo Endoh, Hideo Ohno
  • Patent number: 10644234
    Abstract: 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: Grant
    Filed: August 28, 2017
    Date of Patent: May 5, 2020
    Assignee: TOHOKU UNIVERSITY
    Inventors: Kenchi Ito, Tetsuo Endoh, Shoji Ikeda, Hideo Sato, Hideo Ohno, Sadahiko Miura, Masaaki Niwa, Hiroaki Honjo
  • Publication number: 20190219633
    Abstract: 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: Application
    Filed: March 22, 2017
    Publication date: July 18, 2019
    Applicant: TOHOKU UNIVERSITY
    Inventors: Kenchi ITO, Tetsuo ENDOH, Hideo SATO, Takashi SAITO, Masakazu MURAGUCHI, Hideo OHNO
  • Publication number: 20190198755
    Abstract: 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: Application
    Filed: August 28, 2017
    Publication date: June 27, 2019
    Inventors: Kenchi ITO, Tetsuo ENDOH, Shoji IKEDA, Hideo SATO, Hideo OHNO, Sadahiko MIURA, Masaaki NIWA, Hiroaki HONJO
  • Publication number: 20190074433
    Abstract: 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: Application
    Filed: November 2, 2018
    Publication date: March 7, 2019
    Applicant: TOHOKU UNIVERSITY
    Inventors: Hideo SATO, Shoji IKEDA, Mathias BERSWEILER, Hiroaki HONJO, Kyota WATANABE, Shunsuke FUKAMI, Fumihiro MATSUKURA, Kenchi ITO, Masaaki NIWA, Tetsuo ENDOH, Hideo OHNO
  • Patent number: 10164174
    Abstract: 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: Grant
    Filed: January 16, 2018
    Date of Patent: December 25, 2018
    Assignee: TOHOKU UNIVERSITY
    Inventors: Hideo Sato, Shoji Ikeda, Mathias Bersweiler, Hiroaki Honjo, Kyota Watanabe, Shunsuke Fukami, Fumihiro Matsukura, Kenchi Ito, Masaaki Niwa, Tetsuo Endoh, Hideo Ohno
  • Publication number: 20180175286
    Abstract: 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: Application
    Filed: January 16, 2018
    Publication date: June 21, 2018
    Applicant: TOHOKU UNIVERSITY
    Inventors: Hideo SATO, Shoji IKEDA, Mathias BERSWEILER, Hiroaki HONJO, Kyota WATANABE, Shunsuke FUKAMI, Fumihiro MATSUKURA, Kenchi ITO, Masaaki NIWA, Tetsuo ENDOH, Hideo OHNO
  • Patent number: 9602103
    Abstract: 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: Grant
    Filed: May 22, 2013
    Date of Patent: March 21, 2017
    Assignee: Hitachi, Ltd.
    Inventors: Katsuya Miura, Susumu Ogawa, Kenchi Ito, Masaki Yamada
  • Publication number: 20160105176
    Abstract: 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: Application
    Filed: May 22, 2013
    Publication date: April 14, 2016
    Inventors: Katsuya MIURA, Susumu OGAWA, Kenchi ITO, Masaki YAMADA
  • Patent number: 9257483
    Abstract: 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: Grant
    Filed: January 13, 2011
    Date of Patent: February 9, 2016
    Assignee: Hitachi, Ltd.
    Inventors: Takashi Ishigaki, Takayuki Kawahara, Riichiro Takemura, Kazuo Ono, Kenchi Ito
  • Patent number: 9042165
    Abstract: 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: Grant
    Filed: January 25, 2011
    Date of Patent: May 26, 2015
    Assignees: Hitachi, Ltd., Tohoku University
    Inventors: Shoji Ikeda, Hideo Ohno, Hiroyuki Yamamoto, Kenchi Ito, Hiromasa Takahashi
  • Patent number: 9000546
    Abstract: 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: Grant
    Filed: December 4, 2012
    Date of Patent: April 7, 2015
    Assignee: Hitachi, Ltd.
    Inventors: Kenchi Ito, Masaki Yamada, Susumu Ogawa
  • Patent number: 8957486
    Abstract: 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: Grant
    Filed: March 4, 2009
    Date of Patent: February 17, 2015
    Assignee: Hitachi, Ltd.
    Inventors: Kenchi Ito, Jun Hayakawa, Katsuya Miura, Hiroyuki Yamamoto
  • Publication number: 20130107616
    Abstract: 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: Application
    Filed: July 9, 2010
    Publication date: May 2, 2013
    Inventors: Hideo Ohno, Shoji Ikeda, Hiroyuki Yamamoto, Kenchi Ito, Hiromasa Takahashi
  • Patent number: 8427864
    Abstract: 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: Grant
    Filed: June 2, 2010
    Date of Patent: April 23, 2013
    Assignee: Hitachi, Ltd.
    Inventors: Takayuki Kawahara, Kiyoo Itoh, Riichiro Takemura, Kenchi Ito
  • Publication number: 20130044537
    Abstract: 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: Application
    Filed: January 13, 2011
    Publication date: February 21, 2013
    Inventors: Takashi Ishigaki, Takayuki Kawahara, Riichiro Takemura, Kazuo Ono, Kenchi Ito
  • Publication number: 20130028013
    Abstract: 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: Application
    Filed: January 25, 2011
    Publication date: January 31, 2013
    Inventors: Shoji Ikeda, Hideo Ohno, Hiroyuki Yamamoto, Kenchi Ito, Hiromasa Takahashi
  • Publication number: 20120081952
    Abstract: 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: Application
    Filed: June 2, 2010
    Publication date: April 5, 2012
    Inventors: Takayuki Kawahara, Kiyoo Itoh, Riichiro Takemura, Kenchi Ito
  • Publication number: 20120012955
    Abstract: 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: Application
    Filed: March 4, 2009
    Publication date: January 19, 2012
    Applicant: HITACHI, LTD.
    Inventors: Kenchi Ito, Jun Hayakawa, Katsuya Miura, Hiroyuki Yamamoto
  • Publication number: 20110222333
    Abstract: Provided is a highly-integrated magnetic memory which employs applied spin torque magnetization reversal and does not require the switching of the current direction at the time of rewrite. The magnetic memory includes a memory cell in which a fixed layer made of a ferromagnetic material, a nonmagnetic layer, a recording layer made of a ferromagnetic material, a nonmagnetic layer, and a magnetization rotation assist layer made of a ferromagnetic material are stacked one on top of another. The magnetic memory performs recording by making the magnetization direction of the recording layer substantially parallel or substantially antiparallel to the magnetization direction of the fixed layer.
    Type: Application
    Filed: May 26, 2009
    Publication date: September 15, 2011
    Inventor: Kenchi Ito