Patents by Inventor Takahiko IIZUKA

Takahiko IIZUKA 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).

  • Publication number: 20200302975
    Abstract: According to one embodiment, a nonvolatile memory device includes first and second word lines, first and second bit lines, memory cells each including a resistance change memory element, a global word line including a first global word line portion including a first end portion, a global bit line including a first global bit line portion including a second end portion. The first and second word lines and the first global bit line portion have a first line width and a first line thickness, the first and second bit lines and the first global word line portion have a second line width and a second line thickness.
    Type: Application
    Filed: September 13, 2019
    Publication date: September 24, 2020
    Applicant: TOSHIBA MEMORY CORPORATION
    Inventors: Takahiko IIZUKA, Daisaburo TAKASHIMA, Ryu OGIWARA
  • Publication number: 20200303001
    Abstract: According to one embodiment, a storage device includes: a memory cell including a storage component to which a plurality of data values are allowed to set in response to a plurality of resistance values of the storage component and a selector connected in series to the storage component; a word line configured to provide a signal to select the memory cell; a bit line configured to receive a data signal from the memory cell; a first conversion circuit configured to nonlinearly convert a first current, generated in response to the data signal input to the bit line, into a first voltage; and a comparison circuit configured to compare the first voltage, converted by the first conversion circuit, with a plurality of reference voltages.
    Type: Application
    Filed: September 3, 2019
    Publication date: September 24, 2020
    Applicant: TOSHIBA MEMORY CORPORATION
    Inventors: Ryu OGIWARA, Daisaburo TAKASHIMA, Takahiko IIZUKA
  • Publication number: 20200098426
    Abstract: According to one embodiment, a memory device includes a memory cell including a resistance change memory element and a selector element, a word line, a bit line connected to one end of the memory cell, an operational amplifier including a non-inverting input connected to the bit line, an output circuit including a first terminal connected to an output of the operational amplifier, a second terminal connected to the bit line, and a charge/discharge circuit including a capacitor, a charge circuit and a discharge circuit, each including one end connected to an inverting input of the operational amplifier. At the time of falling of a write voltage for the memory cell, a potential of the other end of the memory cell is set higher than a potential of the other end of the discharge circuit.
    Type: Application
    Filed: March 14, 2019
    Publication date: March 26, 2020
    Applicant: Toshiba Memory Corporation
    Inventors: Ryu Ogiwara, Daisaburo Takashima, Takahiko Iizuka
  • Patent number: 10468101
    Abstract: A semiconductor memory device comprises a memory cell including a resistance change memory element and a write control circuit for setting a resistance state of the resistance change memory element. The write control circuit applies a first voltage signal when setting the resistance change memory element. The first voltage signal rises in a first rise time from a first reference voltage to a first predetermined voltage, maintains at the first predetermined voltage for a first predetermined time period, and then falls from the first predetermined voltage to the first reference voltage in a first falling time. The write circuit applies a second or third voltage signal according to the state being set in the resistance change memory element. In some examples, a predetermined voltage level of the third signal is applied for a period of time longer than a predetermined level of the first and second voltage signals.
    Type: Grant
    Filed: August 31, 2018
    Date of Patent: November 5, 2019
    Assignee: TOSHIBA MEMORY CORPORATION
    Inventors: Takahiko Iizuka, Daisaburo Takashima
  • Publication number: 20190287615
    Abstract: A semiconductor memory device comprises a memory cell including a resistance change memory element and a write control circuit for setting a resistance state of the resistance change memory element. The write control circuit applies a first voltage signal when setting the resistance change memory element. The first voltage signal rises in a first rise time from a first reference voltage to a first predetermined voltage, maintains at the first predetermined voltage for a first predetermined time period, and then falls from the first predetermined voltage to the first reference voltage in a first falling time. The write circuit applies a second or third voltage signal according to the state being set in the resistance change memory element. In some examples, a predetermined voltage level of the third signal is applied for a period of time longer than a predetermined level of the first and second voltage signals.
    Type: Application
    Filed: August 31, 2018
    Publication date: September 19, 2019
    Inventors: Takahiko IIZUKA, Daisaburo TAKASHIMA
  • Patent number: 10410720
    Abstract: A semiconductor memory device includes a first conductor extending in a first direction and a second conductor extending in a second direction and disposed above the first conductor in a third direction. Third and fourth conductors extend in the first direction and adjacent to each other in the second direction. The third and fourth conductors are above the second conductor. A fifth conductor includes a variable resistance unit and is between the first and second conductors. A sixth conductor includes a variable resistance unit and is between the third and second conductors. A seventh conductor includes a variable resistance unit and is between the fourth and second conductors. A center point of the fifth conductor along a width of the fifth conductor is does not fully overlap with either of the sixth or seventh conductors along the third direction.
    Type: Grant
    Filed: September 4, 2017
    Date of Patent: September 10, 2019
    Assignee: TOSHIBA MEMORY CORPORATION
    Inventors: Takahiko Iizuka, Daisaburo Takashima, Ryu Ogiwara
  • Publication number: 20180277202
    Abstract: A semiconductor memory device includes a first conductor extending in a first direction and a second conductor extending in a second direction and disposed above the first conductor in a third direction. Third and fourth conductors extend in the first direction and adjacent to each other in the second direction. The third and fourth conductors are above the second conductor. A fifth conductor includes a variable resistance unit and is between the first and second conductors. A sixth conductor includes a variable resistance unit and is between the third and second conductors. A seventh conductor includes a variable resistance unit and is between the fourth and second conductors. A center point of the fifth conductor along a width of the fifth conductor is does not fully overlap with either of the sixth or seventh conductors along the third direction.
    Type: Application
    Filed: September 4, 2017
    Publication date: September 27, 2018
    Inventors: Takahiko IIZUKA, Daisaburo TAKASHIMA, Ryu OGIWARA