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: 7965542
    Abstract: A magnetic random access memory includes a memory cell element which includes a first fixed layer, a first recording layer in which a magnetization direction reverses on the basis of a first threshold value, and a first nonmagnetic layer formed between the first fixed layer and the first recording layer, a first interconnection connected to one terminal of the memory cell element, a transistor whose current path has one end connected to the other terminal of the memory cell element, a second interconnection connected to the other end of the current path, and a first resistance change element electrically connected to the memory cell element, and having a resistance value which changes on the basis of a second threshold value.
    Type: Grant
    Filed: January 16, 2008
    Date of Patent: June 21, 2011
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Yoshiaki Asao
  • Patent number: 7932513
    Abstract: A magnetic random access memory includes a bit line running in a first direction, a first word line running in a second direction different from the first direction, and a memory element having a magnetoresistive effect element including a fixed layer having a fixed magnetization direction, a recording layer having a reversible magnetization direction, and a nonmagnetic layer formed between the fixed layer and the recording layer, the magnetization directions in the fixed layer and the recording layer being perpendicular to a film surface, and a heater layer in contact with the magnetoresistive effect element, the memory element being connected to the bit line, and formed to oppose a side surface of the first word line such that the memory element is insulated from the first word line.
    Type: Grant
    Filed: March 6, 2008
    Date of Patent: April 26, 2011
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Keiji Hosotani, Yoshiaki Asao, Toshihiko Nagase
  • Patent number: 7920412
    Abstract: A magnetic random access memory includes a first wiring, a second wiring formed above and spaced apart from the first wiring, a magnetoresistive effect element formed between the first wiring and the second wiring, formed in contact with an upper surface of the first wiring, and having a fixed layer, a recording layer, and a nonmagnetic layer formed between the fixed layer and the recording layer, a metal layer formed on the magnetoresistive effect element and integrated with the magnetoresistive effect element to form stacked layers, a first side insulating film formed on side surfaces of the metal layer, the magnetoresistive effect element, and the first wiring, a first contact formed in contact with a side surface of the first side insulating film, and a third wiring formed on the metal layer and the first contact to electrically connect the magnetoresistive effect element and the first contact.
    Type: Grant
    Filed: October 23, 2009
    Date of Patent: April 5, 2011
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Keiji Hosotani, Yoshiaki Asao, Akihiro Nitayama
  • Patent number: 7919826
    Abstract: A magnetoresistive element includes a first stacked structure formed by sequentially stacking a first fixed layer in which a magnetization direction is fixed and a first nonmagnetic layer, a second stacked structure formed on the first stacked structure by sequentially stacking a free layer in which a magnetization direction is changeable, a second nonmagnetic layer, and a second fixed layer in which a magnetization direction is fixed, and a circumferential wall formed in contact with a circumferential surface of the second stacked structure to surround the second stacked structure, and made of an insulator. A circumferential surface of the first stacked structure is substantially perpendicular. The second stacked structure has a tapered shape which narrows upward.
    Type: Grant
    Filed: April 23, 2008
    Date of Patent: April 5, 2011
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Masayoshi Iwayama, Yoshiaki Asao, Takeshi Kajiyama, Keiji Hosotani
  • Patent number: 7916522
    Abstract: A semiconductor memory device includes n resistance change elements which are arranged in one cell, have a low-resistance state and a high resistance state, are connected in series or parallel, have different resistance values in the same resistance state, and change between the low-resistance state and the high-resistance state under different conditions, and a write circuit which is connected to one end of the n resistance change elements, and applies a pulse current m (1?m?n) times to the n resistance change elements during a write operation. Letting Im be a current value of an mth pulse current, condition I1>I2> . . . >Im holds.
    Type: Grant
    Filed: March 9, 2009
    Date of Patent: March 29, 2011
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Kiyotaro Itagaki, Tsuneo Inaba, Yoshihiro Ueda, Yoshiaki Asao
  • Publication number: 20110068404
    Abstract: A semiconductor device includes a first semiconductor layer and a second semiconductor layer that have a form of fins and are arranged a predetermined distance apart from each other, in which a center portion of each serves as a channel region, and side portions sandwiching the center portion serve as source/drain regions, a gate electrode formed on two side surfaces of each of the channel regions of the first semiconductor layer and the second semiconductor layer, with a gate insulating film interposed therebetween, an insulating film formed to fill a gap between the source/drain regions of the first semiconductor layer and the source/drain regions of the second semiconductor layer, and silicide layers formed on side surfaces of the source/drain regions of the first semiconductor layer and the source/drain regions of the second semiconductor layer that are not covered by the insulating film.
    Type: Application
    Filed: March 17, 2010
    Publication date: March 24, 2011
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Kuniaki SUGIURA, Takeshi KAJIYAMA, Yoshiaki ASAO
  • Publication number: 20110068401
    Abstract: A semiconductor device of an embodiment includes a substrate and a plurality of fins formed on the substrate. The plurality of fins is arranged so that a first distance and a second distance narrower than the first distance are repeated. In addition, the plurality of fins include a semiconductor region in which an impurity concentration of lower portions of side surfaces facing each other in sides forming the first distance is higher than an impurity concentration of lower portions of side surfaces facing each other in sides forming the second distance.
    Type: Application
    Filed: September 14, 2010
    Publication date: March 24, 2011
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Takashi Izumida, Nobutoshi Aoki, Masaki Kondo, Yoshiaki Asao, Satoshi Inaba
  • Publication number: 20110062417
    Abstract: First semiconductor layers are in source/drain regions on the semiconductor substrate. A second semiconductor layer comprises first portions on the first semiconductor layers and a second portion on a channel region between the source/drain regions. Third semiconductor layers are on the first portions of the second semiconductor layer. A gate electrode is around the second portion of the second semiconductor layer via an insulating film. Contact plugs are in the first semiconductor layers, the first portions of the second semiconductor layers and the third semiconductor layers in the source/drain regions. A diameter of the contact plug in the second semiconductor layer is smaller than a diameter of the contact plug in the first and third semiconductor layers.
    Type: Application
    Filed: February 4, 2010
    Publication date: March 17, 2011
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Masayoshi Iwayama, Takeshi Kajiyama, Yoshiaki Asao
  • Publication number: 20110062421
    Abstract: First semiconductor layers are in source/drain regions on the semiconductor substrate. A second semiconductor layer comprises first portions on the first semiconductor layers and a second portion in a linear form in a channel region between the source/drain regions. A gate electrode is around the second portion of the second semiconductor layer via an insulating film. A film thickness of the second portion of the second semiconductor layer is smaller than a film thickness of the first portion of the second semiconductor layer.
    Type: Application
    Filed: February 4, 2010
    Publication date: March 17, 2011
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Masayoshi Iwayama, Yoshiaki Asao, Takeshi Kajiyama
  • Publication number: 20110037108
    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: Application
    Filed: August 11, 2010
    Publication date: February 17, 2011
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Kuniaki SUGIURA, Yoshiaki ASAO, Takeshi KAJIYAMA
  • Patent number: 7869259
    Abstract: A resistance change memory includes a first interconnection, a second interconnection, a first resistance change element which has a first electrode, a second electrode, and a first tunnel insulating film provided between the first electrode and the second electrode, the first tunnel insulating film including a first trap region formed by introducing defects to trap holes or electrons, and the second electrode being connected to the first interconnection, and a first transistor whose current path has one end connected to the first electrode and the other end connected to the second interconnection.
    Type: Grant
    Filed: March 18, 2009
    Date of Patent: January 11, 2011
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Yoshiaki Asao
  • Publication number: 20110002157
    Abstract: A resistance change type memory includes first, second and third drive lines, a resistance change element having one end connected to the third drive line, a first diode having an anode connected to the first drive line and a cathode connected to other end of the first resistance change element, a second diode having an anode connected to other end of the first resistance change element and a cathode connected to the second drive line, and a driver/sinker which supplies a write current to the resistance change element. A write control circuit is arranged such that when first data is written, the write current is caused to flow in a direction from the first drive line to the third drive line, and when second data is written, the write current is caused to flow in a direction from the third drive line to the second drive line.
    Type: Application
    Filed: September 14, 2010
    Publication date: January 6, 2011
    Inventors: Naoharu SHIMOMURA, Yoshiaki Asao
  • Patent number: 7848136
    Abstract: It is possible to reduce writing current without causing fluctuation of the writing characteristic. A magnetic memory includes: a magnetoresistance effect element having a magnetization pinned layer whose magnetization direction is pinned, a storage layer whose magnetization direction is changeable, and a non-magnetic layer provided between the magnetization pinned layer and the storage layer; and a first wiring layer which is electrically connected to the magnetoresistance effect element and extends in a direction substantially perpendicular to a direction of an easy magnetization axis of the storage layer, an end face of the magnetoresistance effect element substantially perpendicular to the direction of the easy magnetization axis of the storage layer and an end face of the first wiring layer substantially perpendicular to the direction of the easy magnetization axis being positioned on the same plane.
    Type: Grant
    Filed: April 10, 2008
    Date of Patent: December 7, 2010
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Hisanori Aikawa, Tomomasa Ueda, Tatsuya Kishi, Takeshi Kajiyama, Yoshiaki Asao, Hiroaki Yoda
  • Publication number: 20100238718
    Abstract: A semiconductor memory device includes a semiconductor substrate including an active area, a first select transistor in the active area, a first interconnection layer above the semiconductor substrate configured to run in a first direction, a first magnetoresistive element above the first interconnection layer including a fixed layer having a fixed magnetization direction, a nonmagnetic layer on the fixed layer, and a recording layer on the nonmagnetic layer having a variable magnetization direction, the fixed layer being electrically connected to the first interconnection layer, the recording layer being electrically connected to a first diffusion region of the first select transistor, and a second interconnection layer configured to run in the first direction and electrically connected to a second diffusion region of the first select transistor.
    Type: Application
    Filed: March 18, 2010
    Publication date: September 23, 2010
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventor: Yoshiaki ASAO
  • Publication number: 20100238711
    Abstract: A resistance-change memory of an aspect of the present invention including a first bit line, second and third bit lines extending in a direction intersecting with the first bit line, first and second word lines, a first select transistor in which a control terminal thereof is connected to the first word line and in which one end of a current path thereof is connected to the second bit line, a second select transistor in which a control terminal thereof is connected to the second word line and in which one end of a current path thereof is connected to the third bit line and in which the end of a current path thereof forms a node together with the other end of the first select transistor, and a resistance-change storage element which has one end connected to the first bit line and the other end connected to the node.
    Type: Application
    Filed: March 17, 2010
    Publication date: September 23, 2010
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventor: Yoshiaki ASAO
  • Publication number: 20100232210
    Abstract: A semiconductor memory device includes variable resistance elements arranged in a memory area and configured to store data according to a resistance variation, each of the variable resistance elements having a first terminal electrically connected to a first line and a second terminal electrically connected to a second line, and dummy elements arranged in the memory area, formed of the same material as the variable resistance element and electrically isolated.
    Type: Application
    Filed: March 12, 2010
    Publication date: September 16, 2010
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Takeshi KAJIYAMA, Yoshiaki ASAO
  • Patent number: 7781803
    Abstract: A semiconductor memory device comprising: a support substrate; an insulating film formed on the support substrate; a semiconductor film formed on the insulating film; a gate insulating film formed on the semiconductor film; a gate electrode film formed on the gate insulating film; and a source region and a drain region formed in the semiconductor film so as to sandwich the gate insulating film in a gate length direction, the source and drain regions contacting the insulating film at the bottom surface, and the semiconductor memory device storing data corresponding to the amount of charges accumulated in the semiconductor film surrounded by the insulating film, the gate insulating film, and the source and drain regions and electrically floated, wherein a border length between the source region and the gate insulating film contiguous to each other is different from a border length between the drain region and the gate insulating film to each other.
    Type: Grant
    Filed: December 19, 2008
    Date of Patent: August 24, 2010
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Jun Nishimura, Yoshiaki Asao
  • Publication number: 20100193850
    Abstract: First and second transistors are formed on a substrate. An interlayer insulating film is formed on the first transistor. A first contact is formed in the interlayer film on a source or a drain of the first transistor. A second contact is formed in the interlayer film on the other of the source or the drain. A first interconnect is formed on the first contact. A magnetoresistive element is formed on the second contact. The magnetoresistive element is arranged in a layer having a height equal to that of the first interconnect from a substrate surface. A third contact is formed in the interlayer film on a source or a drain of the second transistor. A second interconnect is formed on the third contact. The second interconnect is arranged in a layer having a height equal to those of the first interconnect and the magnetoresistive element from the substrate surface.
    Type: Application
    Filed: February 1, 2010
    Publication date: August 5, 2010
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Yoshiaki ASAO, Takeshi KAJIYAMA, Minoru AMANO, Yoshikuni TATEYAMA, Atsushi SHIGETA
  • Publication number: 20100197044
    Abstract: A magnetic material of a magnetoresistive element is formed on a lower electrode. An upper electrode is formed on the magnetic material. A resist for nano-imprint lithography is formed on the upper electrode. A first pattern or a second pattern is formed in the resist by setting a first template or a second template into contact with the resist and curing the resist. The first template has the first pattern that corresponds to the magnetoresistive element and the lower electrode. The second template has the second pattern that corresponds to the magnetoresistive element and the upper electrode. The magnetic material and the lower electrode are patterned at the same time by using the resist having the first pattern, or the magnetic material and the upper electrode are patterned at the same time by using the resist having the second pattern.
    Type: Application
    Filed: February 3, 2010
    Publication date: August 5, 2010
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Takeshi KAJIYAMA, Yoshiaki ASAO, Minoru AMANO, Shigeki TAKAHASHI, Masayoshi IWAYAMA, Kuniaki SUGIURA
  • Patent number: 7767469
    Abstract: A magnetic random access memory includes, a lower electrode, a magnetoresistive element which is arranged above the lower electrode and has side surfaces, and a protective film which covers the side surfaces of the magnetoresistive element, has a same planar shape as the lower electrode, and is formed by one of sputtering, plasma CVD, and ALD.
    Type: Grant
    Filed: April 24, 2008
    Date of Patent: August 3, 2010
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Yoshiaki Asao, Hiroaki Yoda