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).
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Patent number: 8981446Abstract: 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: GrantFiled: September 4, 2013Date of Patent: March 17, 2015Inventors: Takashi Nakazawa, Yoshiaki Asao, Takeshi Kajiyama, Kenji Noma
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Publication number: 20150070964Abstract: 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: ApplicationFiled: January 28, 2014Publication date: March 12, 2015Applicant: Kabushiki Kaisha ToshibaInventors: Yuki YAMADA, Yoshiaki Asao
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Publication number: 20150035097Abstract: 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: ApplicationFiled: October 17, 2014Publication date: February 5, 2015Inventor: Yoshiaki ASAO
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Patent number: 8941197Abstract: 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: GrantFiled: February 9, 2012Date of Patent: January 27, 2015Assignee: Kabushiki Kaisha ToshibaInventors: Takeshi Kajiyama, Yoshiaki Asao
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Publication number: 20140306277Abstract: 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: ApplicationFiled: June 26, 2014Publication date: October 16, 2014Inventor: Yoshiaki ASAO
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Publication number: 20140284533Abstract: 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: ApplicationFiled: August 9, 2013Publication date: September 25, 2014Inventors: Yoshiaki ASAO, Hideaki HARAKAWA
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Publication number: 20140284738Abstract: 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: ApplicationFiled: September 4, 2013Publication date: September 25, 2014Inventors: Takashi NAKAZAWA, Yoshiaki ASAO, Takeshi KAJIYAMA, Kenji NOMA
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Patent number: 8829580Abstract: 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: GrantFiled: August 11, 2010Date of Patent: September 9, 2014Assignee: Kabushiki Kaisha ToshibaInventors: Kuniaki Sugiura, Yoshiaki Asao, Takeshi Kajiyama
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Patent number: 8791535Abstract: 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: GrantFiled: August 19, 2013Date of Patent: July 29, 2014Assignee: Kabushiki Kaisha ToshibaInventor: Yoshiaki Asao
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Publication number: 20140204653Abstract: 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 aType: ApplicationFiled: March 25, 2014Publication date: July 24, 2014Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Toshiharu Watanabe, Yoshiaki Asao
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Patent number: 8779410Abstract: 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: GrantFiled: January 23, 2012Date of Patent: July 15, 2014Assignee: Kabushiki Kaisha ToshibaInventors: Motoyuki Sato, Yoshiaki Asao, Takashi Obara, Takashi Nakazawa
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Publication number: 20140185359Abstract: 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: ApplicationFiled: March 20, 2013Publication date: July 3, 2014Inventors: Hironobu FURUHASHI, Iwao KUNISHIMA, Susumu SHUTO, Yoshiaki ASAO, Gaku SUDO
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Patent number: 8724377Abstract: 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: GrantFiled: March 19, 2012Date of Patent: May 13, 2014Assignee: Kabushiki Kaisha ToshibaInventors: Takaya Yamanaka, Susumu Shuto, Yoshiaki Asao
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Patent number: 8711602Abstract: 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: GrantFiled: March 23, 2012Date of Patent: April 29, 2014Assignee: Kabushiki Kaisha ToshibaInventors: Toshiharu Watanabe, Yoshiaki Asao
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Publication number: 20140063891Abstract: 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: ApplicationFiled: March 5, 2013Publication date: March 6, 2014Applicant: Kabushiki Kaisha ToshibaInventor: Yoshiaki ASAO
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Patent number: 8644059Abstract: 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: GrantFiled: March 13, 2012Date of Patent: February 4, 2014Assignee: Kabushiki Kaisha ToshibaInventor: Yoshiaki Asao
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Publication number: 20140021520Abstract: 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: ApplicationFiled: August 19, 2013Publication date: January 23, 2014Inventor: Yoshiaki ASAO
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Patent number: 8604569Abstract: 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: GrantFiled: October 1, 2008Date of Patent: December 10, 2013Assignee: Kabushiki Kaisha ToshibaInventors: Keiji Hosotani, Yoshiaki Asao
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Patent number: 8542519Abstract: 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: GrantFiled: February 25, 2011Date of Patent: September 24, 2013Assignee: Kabushiki Kaisha ToshibaInventors: Yoshiaki Asao, Takeshi Kajiyama, Kuniaki Sugiura
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Patent number: 8513751Abstract: 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: GrantFiled: March 14, 2012Date of Patent: August 20, 2013Assignee: Kabushiki Kaisha ToshibaInventor: Yoshiaki Asao