Patents by Inventor Tsukasa TOKUTOMI

Tsukasa TOKUTOMI 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: 20200090779
    Abstract: A memory system according to an embodiment includes a semiconductor memory, and a memory controller. The semiconductor memory comprises memory cells and word lines. Each of the word lines is connected to the memory cells. The memory controller executes a patrol operation including a read operation of the semiconductor memory. The word lines are classified into one of first and second groups. The memory controller executes patrol operations in which the word lines are respectively selected in a first patrol period and, in a second patrol period subsequent to the first patrol period, executes a patrol operation in which the word line included in the first group is selected and omits a patrol operation in which the word line included in the second group is selected.
    Type: Application
    Filed: March 6, 2019
    Publication date: March 19, 2020
    Applicant: Toshiba Memory Corporation
    Inventors: Tsukasa TOKUTOMI, Masanobu SHIRAKAWA, Kiwamu WATANABE, Kengo KUROSE
  • Publication number: 20200090763
    Abstract: According to one embodiment, a memory system includes a nonvolatile memory and a memory controller. The memory controller is configured: to store, in a buffer, a data set read from a cell unit, and an expected data set generated by an error correction on the data set; to count a number of first and second memory cells corresponding to a first and a second combination of data in the data set and the expected data set, respectively, among the memory cells in the cell unit; to calculate a shift amount of a read voltage used in a read operation from the cell unit, based on the number of the first and second memory cells; and to apply the shift amount to a next read operation from the first cell unit.
    Type: Application
    Filed: March 11, 2019
    Publication date: March 19, 2020
    Applicant: Toshiba Memory Corporation
    Inventors: Tsukasa Tokutomi, Masanobu Shirakawa, Kengo Kurose, Marie Takada, Ryo Yamaki, Kiyotaka Iwasaki, Yoshihisa Kojima
  • Publication number: 20200090762
    Abstract: According to one embodiment, a memory system includes a semiconductor memory device and a controller. The device includes a plurality of memory cells capable of storing at least first to third data and a word line coupled to the plurality of memory cells. The first data is determined by a first read operation including a first read level. The second data is determined by a second read operation including a second read level. The third data is determined by a third read operation including a third read level. The controller controls the semiconductor memory device to perform a forth read operation including the first and second read levels in a search operation for first to third read voltages corresponding to the first to third read levels, respectively.
    Type: Application
    Filed: March 4, 2019
    Publication date: March 19, 2020
    Applicant: Toshiba Memory Corporation
    Inventors: Masanobu Shirakawa, Tsukasa Tokutomi, Marie Takada
  • Publication number: 20200091169
    Abstract: According to one embodiment, a semiconductor memory device includes: first and second memory cells; a first and second word lines; and a first bit line. The device is configured to execute first to sixth operations. In the first operation, a first voltage is applied to the first word line and a second voltage is applied to a semiconductor layer. In the second operation, the first voltage is applied to the second word line. In the third operation, a third voltage is applied to the first word line. In the fourth operation, the third voltage is applied to the second word line. In the fifth operation, a fourth voltage is applied to the first word line. In the sixth operation, the fourth voltage is applied to the second word line.
    Type: Application
    Filed: March 11, 2019
    Publication date: March 19, 2020
    Applicant: TOSHIBA MEMORY CORPORATION
    Inventors: Tsukasa TOKUTOMI, Masanobu Shirakawa, Takuya Futatsuyama
  • Publication number: 20200075106
    Abstract: According to one embodiment, a memory system includes a semiconductor memory and a controller. The semiconductor memory includes first to fourth word lines and first to fourth memory cells. The controller is configured to issue first and second instructions. The controller is further configured to execute a first operation to obtain a first read voltage based on a threshold distribution of the first memory cell, and a second operation to read data from the second memory cell.
    Type: Application
    Filed: March 11, 2019
    Publication date: March 5, 2020
    Applicant: TOSHIBA MEMORY CORPORATION
    Inventors: Tsukasa TOKUTOMI, Masanobu SHIRAKAWA, Marie TAKADA, Shohei ASAMI, Masamichi FUJIWARA
  • Publication number: 20200075110
    Abstract: According to one embodiment, a nonvolatile memory includes: a memory cell array including memory cells; and a controller configured to execute a first refresh process on receiving a first command. The first refresh process includes reprogramming at least one second memory cell among first memory cells to which data has been programmed in a first group. In executing the first refresh process, the controller is configured to: select the second memory cell by verifying with a first voltage using a first amount in a case where the second memory cell has been programmed using the first voltage; and select the second memory cell by verifying with a second voltage using a second amount in a case where the second memory cell has been programmed using the second voltage.
    Type: Application
    Filed: June 3, 2019
    Publication date: March 5, 2020
    Applicant: Toshiba Memory Corporation
    Inventors: Riki SUZUKI, Masanobu SHIRAKAWA, Yoshihisa KOJIMA, Marie TAKADA, Tsukasa TOKUTOMI
  • Patent number: 10541030
    Abstract: According to one embodiment, a memory system includes a semiconductor memory and a controller. The semiconductor memory includes: first memory cells, first word lines, a first row decoder, and a driver circuit. The first row decoder includes first transistors capable of coupling the first word lines to first signal lines, and a first block decoder supplying a first block selection signal to the first transistors. When the controller issues a data read command, the first block decoder asserts the first block selection signal to allow the first transistors to transfer a first voltage to a selected first word line, and a second voltage to unselected other first word lines. After data is read, the first block decoder continues asserting the first block selection signal, and the driver circuit transfers a third voltage.
    Type: Grant
    Filed: March 9, 2018
    Date of Patent: January 21, 2020
    Assignee: Toshiba Memory Corporation
    Inventors: Masanobu Shirakawa, Marie Takada, Tsukasa Tokutomi, Yoshihisa Kojima, Kiichi Tachi
  • Publication number: 20190377636
    Abstract: In general, according to an embodiment, a memory system includes a memory device including a memory cell; and a controller. The controller is configured to: receive first data from the memory cell in a first data reading; receive second data from the memory cell in a second data reading that is different from the first data reading; convert a first value that is based on the first data and the second data, to a second value in accordance with a first relationship; and convert the first value to a third value in accordance with a second relationship that is different from the first relationship.
    Type: Application
    Filed: August 21, 2019
    Publication date: December 12, 2019
    Applicant: Toshiba Memory Corporation
    Inventors: Tsukasa TOKUTOMI, Masanobu SHIRAKAWA, Marie TAKADA, Masamichi FUJIWARA, Kazumasa YAMAMOTO, Naoaki KOKUBUN, Tatsuro HITOMI, Hironori UCHIKAWA
  • Publication number: 20190362783
    Abstract: According to an embodiment, a control circuitry performing: a first operation of reading data out of a memory cell with a first voltage applied to a word line while changing the first voltage by a first shift amount within a first range, and a second operation of reading data out of the memory cell with a second voltage applied to the word line while changing the second voltage by a second shift amount within a second range, wherein the second shift amount is smaller than the first shift amount, and wherein the control circuitry performs the second operation to apply the second voltage to the word line subsequently to application of the first voltage to the word line in the first operation.
    Type: Application
    Filed: August 9, 2019
    Publication date: November 28, 2019
    Applicant: Toshiba Memory Corporation
    Inventors: Tsukasa Tokutomi, Masanobu Shirakawa, Marie Takada
  • Patent number: 10431299
    Abstract: According to an embodiment, a control circuitry performing: a first operation of reading data out of a memory cell with a first voltage applied to a word line while changing the first voltage by a first shift amount within a first range, and a second operation of reading data out of the memory cell with a second voltage applied to the word line while changing the second voltage by a second shift amount within a second range, wherein the second shift amount is smaller than the first shift amount, and wherein the control circuitry performs the second operation to apply the second voltage to the word line subsequently to application of the first voltage to the word line in the first operation.
    Type: Grant
    Filed: December 13, 2018
    Date of Patent: October 1, 2019
    Assignee: Toshiba Memory Corporation
    Inventors: Tsukasa Tokutomi, Masanobu Shirakawa, Marie Takada
  • Patent number: 10430275
    Abstract: In general, according to an embodiment, a memory system includes a memory device including a memory cell; and a controller. The controller is configured to: receive first data from the memory cell in a first data reading; receive second data from the memory cell in a second data reading that is different from the first data reading; convert a first value that is based on the first data and the second data, to a second value in accordance with a first relationship; and convert the first value to a third value in accordance with a second relationship that is different from the first relationship.
    Type: Grant
    Filed: March 9, 2018
    Date of Patent: October 1, 2019
    Assignee: Toshiba Memory Corporation
    Inventors: Tsukasa Tokutomi, Masanobu Shirakawa, Marie Takada, Masamichi Fujiwara, Kazumasa Yamamoto, Naoaki Kokubun, Tatsuro Hitomi, Hironori Uchikawa
  • Publication number: 20190294367
    Abstract: According to one embodiment, a memory system includes a semiconductor memory and a controller. The memory system is capable of executing a first operation and a second operation. In the first operation, the controller issues a first command sequence, the semiconductor memory applies a first voltage to a first word line and applies a second voltage to a second word line to read data from the first memory, and the read data is transmitted to the controller from the semiconductor memory. In the second operation, the controller issues a second command sequence, the semiconductor memory applies a third voltage to the first word line and applies a fourth voltage to the second word line, and data held in the memory cell array is left untransmitted to the controller.
    Type: Application
    Filed: August 31, 2018
    Publication date: September 26, 2019
    Applicant: Toshiba Memory Corporation
    Inventors: Marie Takada, Masanobu Shirakawa, Tsukasa Tokutomi
  • Publication number: 20190259459
    Abstract: According to an embodiment, a semiconductor memory, on receiving a first command, applies a voltage within a first range and a voltage within a second range to a word line and reads a first bit from a memory cell, and, on receiving a second command, applies a voltage within a third range to the word line and reads a second bit from the memory cell. The controller issues the first command a plurality of times and changes the voltages to be applied to the word line within the first range and the second range in accordance with the plurality of first commands, specifies a first and second voltage within the first and the second range, respectively, and estimates a third voltage within the third range. The voltage applied to read the second bit is the estimated third voltage.
    Type: Application
    Filed: April 29, 2019
    Publication date: August 22, 2019
    Applicant: Toshiba Memory Corporation
    Inventors: Tsukasa Tokutomi, Masanobu Shirakawa, Marie Takada
  • Patent number: 10325664
    Abstract: According to an embodiment, a semiconductor memory, on receiving a first command, applies a voltage within a first range and a voltage within a second range to a word line and reads a first bit from a memory cell, and, on receiving a second command, applies a voltage within a third range to the word line and reads a second bit from the memory cell. The controller issues the first command a plurality of times and changes the voltages to be applied to the word line within the first range and the second range in accordance with the plurality of first commands, specifies a first and second voltage within the first and the second range, respectively, and estimates a third voltage within the third range. The voltage applied to read the second bit is the estimated third voltage.
    Type: Grant
    Filed: September 7, 2017
    Date of Patent: June 18, 2019
    Assignee: Toshiba Memory Corporation
    Inventors: Tsukasa Tokutomi, Masanobu Shirakawa, Marie Takada
  • Publication number: 20190130968
    Abstract: According to an embodiment, a control circuitry performing: a first operation of reading data out of a memory cell with a first voltage applied to a word line while changing the first voltage by a first shift amount within a first range, and a second operation of reading data out of the memory cell with a second voltage applied to the word line while changing the second voltage by a second shift amount within a second range, wherein the second shift amount is smaller than the first shift amount, and wherein the control circuitry performs the second operation to apply the second voltage to the word line subsequently to application of the first voltage to the word line in the first operation.
    Type: Application
    Filed: December 13, 2018
    Publication date: May 2, 2019
    Applicant: Toshiba Memory Corporation
    Inventors: Tsukasa TOKUTOMI, Masanobu SHIRAKAWA, Marie TAKADA
  • Publication number: 20190087264
    Abstract: In general, according to an embodiment, a memory system includes a memory device including a memory cell; and a controller. The controller is configured to: receive first data from the memory cell in a first data reading; receive second data from the memory cell in a second data reading that is different from the first data reading; convert a first value that is based on the first data and the second data, to a second value in accordance with a first relationship; and convert the first value to a third value in accordance with a second relationship that is different from the first relationship.
    Type: Application
    Filed: March 9, 2018
    Publication date: March 21, 2019
    Applicant: Toshiba Memory Corporation
    Inventors: Tsukasa Tokutomi, Masanobu Shirakawa, Marie Takada, Masamichi Fujiwara, Kazumasa Yamamoto, Naoaki Kokubun, Tatsuro Hitomi, Hironori Uchikawa
  • Publication number: 20190088333
    Abstract: According to one embodiment, a memory system includes a semiconductor memory and a controller. The semiconductor memory includes: first memory cells, first word lines, a first row decoder, and a driver circuit. The first row decoder includes first transistors capable of coupling the first word lines to first signal lines, and a first block decoder supplying a first block selection signal to the first transistors. When the controller issues a data read command, the first block decoder asserts the first block selection signal to allow the first transistors to transfer a first voltage to a selected first word line, and a second voltage to unselected other first word lines. After data is read, the first block decoder continues asserting the first block selection signal, and the driver circuit transfers a third voltage.
    Type: Application
    Filed: March 9, 2018
    Publication date: March 21, 2019
    Applicant: Toshiba Memory Corporation
    Inventors: Masanobu SHIRAKAWA, Marie Takada, Tsukasa Tokutomi, Yoshihisa Kojima, Kiichi Tachi
  • Patent number: 10204680
    Abstract: According to an embodiment, a control circuitry performing: a first operation of reading data out of a memory cell with a first voltage applied to a word line while changing the first voltage by a first shift amount within a first range, and a second operation of reading data out of the memory cell with a second voltage applied to the word line while changing the second voltage by a second shift amount within a second range, wherein the second shift amount is smaller than the first shift amount, and wherein the control circuitry performs the second operation to apply the second voltage to the word line subsequently to application of the first voltage to the word line in the first operation.
    Type: Grant
    Filed: September 7, 2017
    Date of Patent: February 12, 2019
    Assignee: Toshiba Memory Corporation
    Inventors: Tsukasa Tokutomi, Masanobu Shirakawa, Marie Takada
  • Patent number: 10141061
    Abstract: According to one embodiment, a memory system includes a semiconductor memory and a controller. The semiconductor memory is configured to execute a first to third read operations. In the first read operation, a first voltage is applied to a selected word line. In the second read operation, a second voltage different from the first voltage and a third voltage are applied to the selected word line. In the third read operation, a fourth voltage different from the first to third voltages and a fifth voltage are applied to the selected word line. An absolute value of a difference between the second voltage and the fourth voltage is different from an absolute value of a difference between the third voltage and the fifth voltage.
    Type: Grant
    Filed: September 13, 2017
    Date of Patent: November 27, 2018
    Assignee: Toshiba Memory Corporation
    Inventors: Marie Takada, Masanobu Shirakawa, Tsukasa Tokutomi
  • Publication number: 20180277228
    Abstract: According to one embodiment, a memory system includes a semiconductor memory and a controller. The semiconductor memory is configured to execute a first to third read operations. In the first read operation, a first voltage is applied to a selected word line. In the second read operation, a second voltage different from the first voltage and a third voltage are applied to the selected word line. In the third read operation, a fourth voltage different from the first to third voltages and a fifth voltage are applied to the selected word line. An absolute value of a difference between the second voltage and the fourth voltage is different from an absolute value of a difference between the third voltage and the fifth voltage.
    Type: Application
    Filed: September 13, 2017
    Publication date: September 27, 2018
    Applicant: Toshiba Memory Corporation
    Inventors: Marie TAKADA, Masanobu Shirakawa, Tsukasa Tokutomi