Patents by Inventor Yoshiaki Asao

Yoshiaki Asao 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: 8981446
    Abstract: According to one embodiment, a magnetic memory including an isolation region with an insulator in a trench is disclosed. The isolation region defines active areas extending in a 1st direction and having 1st and 2nd active areas, an isolation region extending in a 2nd direction perpendicular to the 1st direction exists between the 1st and 2nd active areas. 1st and 2nd word lines extending in the 2nd direction are buried in a surface of semiconductor substrate. 1st and 2nd select transistors connected to the word lines are on the 1st active area. 1st and 2nd variable resistance elements connected to drain regions of the 1st and 2nd select transistors are on the 1st active area.
    Type: Grant
    Filed: September 4, 2013
    Date of Patent: March 17, 2015
    Inventors: Takashi Nakazawa, Yoshiaki Asao, Takeshi Kajiyama, Kenji Noma
  • Publication number: 20150070964
    Abstract: A semiconductor memory device according to an embodiment includes a semiconductor layer, a gate electrode, a ferroelectric film provided between the semiconductor layer and the gate electrode, a first impurity region of a first conductivity type provided on one side of the gate electrode in the semiconductor layer, a second impurity region of a second conductivity type provided on the other side of the gate electrode in the semiconductor layer, a third impurity region of the first conductivity type provided between the first impurity region and the second impurity region in the semiconductor layer facing the gate electrode and having a lower first-conductivity-type impurity concentration than the first impurity region, a first wiring connected to the first impurity region through a connection portion contacting with the first impurity region, and a second wiring connected to the second impurity region through a connection portion contacting with the second impurity region.
    Type: Application
    Filed: January 28, 2014
    Publication date: March 12, 2015
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Yuki YAMADA, Yoshiaki Asao
  • Publication number: 20150035097
    Abstract: A memory includes a semiconductor substrate. Magnetic tunnel junction elements are provided above the semiconductor substrate. Each of the magnetic tunnel junction elements stores data by a change in a resistance state, and the data is rewritable by a current. Cell transistors are provided on the semiconductor substrate. Each of the cell transistors is in a conductive state when the current is applied to the corresponding magnetic tunnel junction element. Gate electrodes are included in the respective cell transistors. Each of the gate electrodes controls the conductive state of the corresponding cell transistor. In active areas, the cell transistors are provided, and the active areas extend in an extending direction of intersecting the gate electrodes at an angle of (90-atan(?)) degrees.
    Type: Application
    Filed: October 17, 2014
    Publication date: February 5, 2015
    Inventor: Yoshiaki ASAO
  • Patent number: 8941197
    Abstract: A magnetic random access memory which is a memory cell array including a magnetoresistive effect element having a fixed layer whose magnetization direction is fixed, a recording layer whose magnetization direction is reversible, and a non-magnetic layer provided between the fixed layer and the recording layer, wherein all conductive layers in the memory cell array arranged below the magnetoresistive effect element are formed of materials each containing an element selected from a group including W, Mo, Ta, Ti, Zr, Nb, Cr, Hf, V, Co, and Ni.
    Type: Grant
    Filed: February 9, 2012
    Date of Patent: January 27, 2015
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Takeshi Kajiyama, Yoshiaki Asao
  • Publication number: 20140306277
    Abstract: A memory includes a semiconductor substrate. Magnetic tunnel junction elements are provided above the semiconductor substrate. Each of the magnetic tunnel junction elements stores data by a change in a resistance state, and the data is rewritable by a current. Cell transistors are provided on the semiconductor substrate. Each of the cell transistors is in a conductive state when the current is applied to the corresponding magnetic tunnel junction element. Gate electrodes are included in the respective cell transistors. Each of the gate electrodes controls the conductive state of the corresponding cell transistor. In active areas, the cell transistors are provided, and the active areas extend in an extending direction of intersecting the gate electrodes at an angle of (90?atan(?)) degrees.
    Type: Application
    Filed: June 26, 2014
    Publication date: October 16, 2014
    Inventor: Yoshiaki ASAO
  • Publication number: 20140284533
    Abstract: According to one embodiment, a semiconductor memory device comprises a cell transistor includes a first gate electrode buried in a semiconductor substrate and a first diffusion layer and a second diffusion layer formed to sandwich the first gate electrode, a first lower electrode formed on the first diffusion layer, a magnetoresistive element formed on the first lower electrode to store data according to a change in a magnetization state and connected to a bit line located above, a second lower electrode formed on the second diffusion layer, and a first contact formed on the second lower electrode and connected to a source line located above. A contact area between the second lower electrode and the second diffusion layer is larger than a contact area between the first contact and the second lower electrode.
    Type: Application
    Filed: August 9, 2013
    Publication date: September 25, 2014
    Inventors: Yoshiaki ASAO, Hideaki HARAKAWA
  • Publication number: 20140284738
    Abstract: According to one embodiment, a magnetic memory including an isolation region with an insulator in a trench is disclosed. The isolation region defines active areas extending in a 1st direction and having 1st and 2nd active areas, an isolation region extending in a 2nd direction perpendicular to the 1st direction exists between the 1st and 2nd active areas. 1st and 2nd word lines extending in the 2nd direction are buried in a surface of semiconductor substrate. 1st and 2nd select transistors connected to the word lines are on the 1st active area. 1st and 2nd variable resistance elements connected to drain regions of the 1st and 2nd select transistors are on the 1st active area.
    Type: Application
    Filed: September 4, 2013
    Publication date: September 25, 2014
    Inventors: Takashi NAKAZAWA, Yoshiaki ASAO, Takeshi KAJIYAMA, Kenji NOMA
  • Patent number: 8829580
    Abstract: According to one embodiment, a magnetoresistive memory includes first and second contact plugs in a first interlayer insulating film, a lower electrode on the first interlayer insulating film, a magnetoresistive effect element on the lower electrode, and an upper electrode on the magnetoresistive effect element. The lower electrode has a tapered cross-sectional shape in which a dimension of a bottom surface of the lower electrode is longer than a dimension of an upper surface of the lower electrode, one end of the lower electrode is in contact with an upper surface of the first contact plug. The magnetoresistive effect element is provided at a position shifted from a position immediately above the first contact plug in a direction parallel to a surface of the semiconductor substrate.
    Type: Grant
    Filed: August 11, 2010
    Date of Patent: September 9, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Kuniaki Sugiura, Yoshiaki Asao, Takeshi Kajiyama
  • Patent number: 8791535
    Abstract: A memory includes a semiconductor substrate. Magnetic tunnel junction elements are provided above the semiconductor substrate. Each of the magnetic tunnel junction elements stores data by a change in a resistance state, and the data is rewritable by a current. Cell transistors are provided on the semiconductor substrate. Each of the cell transistors is in a conductive state when the current is applied to the corresponding magnetic tunnel junction element. Gate electrodes are included in the respective cell transistors. Each of the gate electrodes controls the conductive state of the corresponding cell transistor. In active areas, the cell transistors are provided, and the active areas extend in an extending direction of intersecting the gate electrodes at an angle of (90?atan(?)) degrees.
    Type: Grant
    Filed: August 19, 2013
    Date of Patent: July 29, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Yoshiaki Asao
  • Publication number: 20140204653
    Abstract: A semiconductor memory device includes: a plurality of word lines extending in a first direction; first to third bit lines extending in a second direction that intersects with the first direction; a plurality of variable resistance elements each having a first terminal connected to either one of the first and third bit lines; a plurality of active areas extending in a direction oblique to the first direction while intersecting with the first to third bit lines; a plurality of select transistors provided on the active areas and each having a gate connected to a corresponding one of the word lines, and a current path whose one end is connected to a second terminal of a corresponding one of the variable resistance elements; and a plurality of contact plugs each connecting the other end of the current path of a corresponding one of the select transistors to the second bit line, wherein each of the active areas includes two select transistors sharing a diffusion region, the variable resistance elements includes a
    Type: Application
    Filed: March 25, 2014
    Publication date: July 24, 2014
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Toshiharu Watanabe, Yoshiaki Asao
  • Patent number: 8779410
    Abstract: According to one embodiment, a resistance change memory includes resistance change elements, vias and sidewall insulating layers, the elements and the vias provided alternately in a first direction and a second direction orthogonal to the first direction, and the sidewall insulating layers provided on sidewalls of the elements. The elements are provided in a lattice pattern having a constant pitch. A thickness of each of the sidewall insulating layers in a direction orthogonal to the sidewalls is a value for contacting the sidewall insulating layers each other or more to form holes between the sidewall insulating layers. The vias are provided in the holes respectively.
    Type: Grant
    Filed: January 23, 2012
    Date of Patent: July 15, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Motoyuki Sato, Yoshiaki Asao, Takashi Obara, Takashi Nakazawa
  • Publication number: 20140185359
    Abstract: According to one embodiment, a memory device includes n (n being an integer of 2 or more) resistance change films being series connected to each other. Each of the resistance change films is a superlattice film in which a plurality of pairs of a first crystal layer made of a first compound and a second crystal layer made of a second compound are alternately stacked. Average composition of the entire resistance change film or arrangement pitch of the first crystal layers and the second crystal layers are mutually different among the n resistance change films.
    Type: Application
    Filed: March 20, 2013
    Publication date: July 3, 2014
    Inventors: Hironobu FURUHASHI, Iwao KUNISHIMA, Susumu SHUTO, Yoshiaki ASAO, Gaku SUDO
  • Patent number: 8724377
    Abstract: According to one embodiment, a memory device includes: a first signal line; a second signal line; a transistor; a first memory region; and a second memory region. The transistor controls a conduction of each of a current flowing between the first and the second signal lines and an opposite current. The first memory region has a first magnetic tunnel junction element. A magnetization direction thereof becomes parallel when a current flows in one direction, and the magnetization direction becomes antiparallel when a current in another direction. The second memory region has a second magnetic tunnel junction element. A magnetization direction thereof becomes parallel when a current flows in one direction, and becomes antiparallel when a current flows in another first direction.
    Type: Grant
    Filed: March 19, 2012
    Date of Patent: May 13, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Takaya Yamanaka, Susumu Shuto, Yoshiaki Asao
  • Patent number: 8711602
    Abstract: A semiconductor memory device includes: plural word lines extending in a first direction; first to third bit lines extending in a second direction that intersects with the first direction; plural variable resistance elements each having a first terminal connected to either one of the first and third bit lines; plural active areas extending in a direction oblique to the first direction while intersecting with the first to third bit lines; plural select transistors provided on the active areas and each having a gate connected to a corresponding one of the word lines, and a current path whose one end is connected to a second terminal of a corresponding one of the variable resistance elements; and plural contact plugs each connecting the other end of the current path of a corresponding one of the select transistors to the second bit line.
    Type: Grant
    Filed: March 23, 2012
    Date of Patent: April 29, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Toshiharu Watanabe, Yoshiaki Asao
  • Publication number: 20140063891
    Abstract: According to one or more embodiments of the present invention, the semiconductor memory device of this disclosure includes the first bit line and the second bit line. Each of the multiple memory cells includes a memory element and a transistor, which are connected in series between the first and the second bit lines. Multiple memory cells are connected in parallel between the first and the second bit lines. In the first memory cell, its memory element is connected to the first bit line, and its transistor is connected to the second bit line. In the second memory cell, its memory element is connected to the second bit line, and its transistor is connected to the first bit line.
    Type: Application
    Filed: March 5, 2013
    Publication date: March 6, 2014
    Applicant: Kabushiki Kaisha Toshiba
    Inventor: Yoshiaki ASAO
  • Patent number: 8644059
    Abstract: A memory includes MTJ elements. Active areas are separated to correspond to cell transistors, respectively, and extend in a first direction substantially orthogonal to an extending direction of gates of the cell transistors. The active areas are arranged in the first direction and constitute a plurality of active area columns. Two active area columns adjacent in a second direction are arranged to be half-pitch staggered in the first direction. As viewed from above surfaces of the active areas, each MTJ element is arranged to overlap with one end of each of the active areas. The first and second wirings extend while being folded back in a direction inclined with respect to the first and second directions in order to overlap with the MTJ elements alternately in the adjacent active area columns.
    Type: Grant
    Filed: March 13, 2012
    Date of Patent: February 4, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Yoshiaki Asao
  • Publication number: 20140021520
    Abstract: A memory includes a semiconductor substrate. Magnetic tunnel junction elements are provided above the semiconductor substrate. Each of the magnetic tunnel junction elements stores data by a change in a resistance state, and the data is rewritable by a current. Cell transistors are provided on the semiconductor substrate. Each of the cell transistors is in a conductive state when the current is applied to the corresponding magnetic tunnel junction element. Gate electrodes are included in the respective cell transistors. Each of the gate electrodes controls the conductive state of the corresponding cell transistor. In active areas, the cell transistors are provided, and the active areas extend in an extending direction of intersecting the gate electrodes at an angle of (90-atan(1/3)) degrees.
    Type: Application
    Filed: August 19, 2013
    Publication date: January 23, 2014
    Inventor: Yoshiaki ASAO
  • Patent number: 8604569
    Abstract: A magnetoresistive element includes a first electrode layer, a first fixed layer provided on the first electrode layer and having a fixed magnetization direction, a first intermediate layer provided on the first fixed layer and made of a metal oxide, a free layer provided on the first intermediate layer and having a variable magnetization direction, and a second electrode layer provided on the free layer. At least one of the first electrode layer and the second electrode layer contains a conductive metal oxide.
    Type: Grant
    Filed: October 1, 2008
    Date of Patent: December 10, 2013
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Keiji Hosotani, Yoshiaki Asao
  • Patent number: 8542519
    Abstract: According to one embodiment, a semiconductor memory device is disclosed. The device includes MOSFET1 and MOSFET2 arranged in a first direction, variable resistive element (hereafter R1) above MOSFET1 and MOSFET2, a lower end of the R1 being connected to drains of MOSFET1 and MOSFET2, MOSFET3 and MOSFET4 arranged in the first direction, variable resistive element (hereafter R2) above MOSFET3 and MOSFET4, and a lower end of the R2 being connected to drains of MOSFET3 and MOSFET4. The device further includes first wiring line extending in the first direction and connected to sources of MOSFET1 and MOSFET2, second wiring line extending in the first direction and connected to sources of MOSFET3 and MOSFET4, upper electrode connecting upper end of the R1 and upper end of the R2, and third wiring line extending in the first direction and connected to the upper electrode.
    Type: Grant
    Filed: February 25, 2011
    Date of Patent: September 24, 2013
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Yoshiaki Asao, Takeshi Kajiyama, Kuniaki Sugiura
  • Patent number: 8513751
    Abstract: A memory includes a semiconductor substrate. Magnetic tunnel junction elements are provided above the semiconductor substrate. Each of the magnetic tunnel junction elements stores data by a change in a resistance state, and the data is rewritable by a current. Cell transistors are provided on the semiconductor substrate. Each of the cell transistors is in a conductive state when the current is applied to the corresponding magnetic tunnel junction element. Gate electrodes are included in the respective cell transistors. Each of the gate electrodes controls the conductive state of the corresponding cell transistor. In active areas, the cell transistors are provided, and the active areas extend in an extending direction of intersecting the gate electrodes at an angle of (90-a tan(?)) degrees.
    Type: Grant
    Filed: March 14, 2012
    Date of Patent: August 20, 2013
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Yoshiaki Asao