Patents by Inventor Hiroki Date

Hiroki Date 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: 20240096430
    Abstract: In one embodiment, a semiconductor storage device includes memory cell transistors, and a word line electrically connected to the memory cell transistors. The device further includes a voltage generator configured to generate a first voltage transferred to the word line, the voltage generator including a voltage divider configured to divide the first voltage with first and second resistance elements, the first or second resistance element being a variable resistance element that receives a first digital signal indicating a resistance value and is changeable to the resistance value. The device further includes a control unit configured to output the first digital signal, wherein the control unit outputs the first digital signal such that a theoretical waveform of the first voltage in boosting the first voltage in an erasing verifying operation is different from a theoretical waveform of the first voltage in boosting the first voltage in a reading operation.
    Type: Application
    Filed: June 20, 2023
    Publication date: March 21, 2024
    Applicant: Kioxia Corporation
    Inventor: Hiroki DATE
  • Patent number: 11869597
    Abstract: A semiconductor storage device in an embodiment includes a plurality of planes each including a memory cell array, a voltage generation circuit configured to apply a first intermediate voltage to an adjacent word line adjacent to a selected word line in a former half of a program period and apply a second intermediate voltage higher than the first intermediate voltage to the adjacent word line in a latter half of the program period, a discharge circuit configured to feed a discharge current from the selected word line in a period corresponding to a period in which the second intermediate voltage is applied to the adjacent word line, and a control circuit configured to set a discharge characteristic of the discharge circuit according to a number of the planes.
    Type: Grant
    Filed: September 1, 2021
    Date of Patent: January 9, 2024
    Assignee: Kioxia Corporation
    Inventors: Takeshi Nakano, Yuzuru Shibazaki, Hideyuki Kataoka, Junichi Sato, Hiroki Date
  • Patent number: 11749348
    Abstract: A semiconductor storage device includes: a plurality of first memory cells; a word line connected to gates of the first memory cells; a voltage generation circuit configured to generate voltage to be supplied to the word line on the basis of a set value; and a control unit configured to execute a write sequence that includes a plurality of loops, each loop including a program operation to increase a threshold voltage of at least part of the first memory cells to thereby write data to the first memory cells and a verify operation to verify the data written to the first memory cells. The voltage generation circuit generates voltage to be supplied to the word line at start of the verify operation on the basis of a first set value, and the control unit adjusts the first set value in accordance with progress of the write sequence.
    Type: Grant
    Filed: August 26, 2021
    Date of Patent: September 5, 2023
    Assignee: Kioxia Corporation
    Inventor: Hiroki Date
  • Publication number: 20230088312
    Abstract: A semiconductor memory device includes a memory cell array, a decoder circuit, a voltage supply circuit, and a control circuit. The voltage supply circuit is configured to generate a first voltage supplied to the decoder circuit, a second voltage supplied to a select gate line, and a third voltage supplied to a word line. The control circuit, during a read operation with respect to a memory cell transistor, starts a first control operation on the voltage supply circuit to boost the first voltage to a first target voltage, during the first control operation, starts a second control operation to boost the second voltage, and during the second control operation, starts a third control operation to boost the third voltage. During the first control operation, the first voltage is increased to and maintained at an intermediate voltage lower than the first target voltage for a certain period of time.
    Type: Application
    Filed: February 24, 2022
    Publication date: March 23, 2023
    Inventor: Hiroki DATE
  • Publication number: 20220375517
    Abstract: A semiconductor storage device includes: a first memory cell and a second memory cell that are adjacent to each other and connected to each other in series; a first word line connected to the first memory cell; a second word line connected to the second memory cell; and a control circuit. The control circuit is configured to, in a first read operation to read a first bit stored in the first memory cell, apply a first voltage to the first word line, and then, apply a first read voltage lower than the first voltage, to the first word line, and apply a second voltage to the second word line, and then, apply a third voltage lower than the second voltage and higher than the first voltage, to the second word line. The third voltage is applied to the second word line after the first read voltage is applied to the first word line.
    Type: Application
    Filed: August 5, 2022
    Publication date: November 24, 2022
    Applicant: Kioxia Corporation
    Inventors: Hiroki DATE, Takeshi NAKANO
  • Publication number: 20220301630
    Abstract: A semiconductor storage device in an embodiment includes a plurality of planes each including a memory cell array, a voltage generation circuit configured to apply a first intermediate voltage to an adjacent word line adjacent to a selected word line in a former half of a program period and apply a second intermediate voltage higher than the first intermediate voltage to the adjacent word line in a latter half of the program period, a discharge circuit configured to feed a discharge current from the selected word line in a period corresponding to a period in which the second intermediate voltage is applied to the adjacent word line, and a control circuit configured to set a discharge characteristic of the discharge circuit according to a number of the planes.
    Type: Application
    Filed: September 1, 2021
    Publication date: September 22, 2022
    Applicant: Kioxia Corporation
    Inventors: Takeshi NAKANO, Yuzuru SHIBAZAKI, Hideyuki KATAOKA, Junichi SATO, Hiroki DATE
  • Publication number: 20220301627
    Abstract: A semiconductor storage device includes: a plurality of first memory cells; a word line connected to gates of the first memory cells; a voltage generation circuit configured to generate voltage to be supplied to the word line on the basis of a set value; and a control unit configured to execute a write sequence that includes a plurality of loops, each loop including a program operation to increase a threshold voltage of at least part of the first memory cells to thereby write data to the first memory cells and a verify operation to verify the data written to the first memory cells. The voltage generation circuit generates voltage to be supplied to the word line at start of the verify operation on the basis of a first set value, and the control unit adjusts the first set value in accordance with progress of the write sequence.
    Type: Application
    Filed: August 26, 2021
    Publication date: September 22, 2022
    Applicant: Kioxia Corporation
    Inventor: Hiroki DATE
  • Patent number: 11450383
    Abstract: A semiconductor storage device includes: a first memory cell and a second memory cell that are adjacent to each other and connected to each other in series; a first word line connected to the first memory cell; a second word line connected to the second memory cell; and a control circuit. The control circuit is configured to, in a first read operation to read a first bit stored in the first memory cell, apply a first voltage to the first word line, and then, apply a first read voltage lower than the first voltage, to the first word line, and apply a second voltage to the second word line, and then, apply a third voltage lower than the second voltage and higher than the first voltage, to the second word line. The third voltage is applied to the second word line after the first read voltage is applied to the first word line.
    Type: Grant
    Filed: February 24, 2021
    Date of Patent: September 20, 2022
    Assignee: KIOXIA CORPORATION
    Inventors: Hiroki Date, Takeshi Nakano
  • Publication number: 20220254393
    Abstract: In a semiconductor memory device, in a write operation performed to a memory cell transistor, a first voltage is applied to a first word line and a second voltage lower than the first voltage is applied to a second word line. When a stop command is received during the write operation, a third voltage lower than the second voltage is applied to the first and second word lines, thereafter a fourth voltage higher than the third voltage is applied to a first selection line, thereon or thereafter a fifth voltage higher than the fourth voltage is applied to the first and second word lines, thereafter a sixth voltage lower than the fourth voltage is applied to the first selection line, and thereafter a seventh voltage is applied to the first and second word lines.
    Type: Application
    Filed: April 26, 2022
    Publication date: August 11, 2022
    Applicant: Kioxia Corporation
    Inventor: Hiroki DATE
  • Patent number: 11335388
    Abstract: In a semiconductor memory device, in a write operation performed to a memory cell transistor, a first voltage is applied to a first word line and a second voltage lower than the first voltage is applied to a second word line. When a command to stop is received during the write operation, a third voltage lower than the second voltage is applied to the first and second word lines, thereafter a fourth voltage higher than the third voltage is applied to a first selection line, thereon or thereafter a fifth voltage higher than the fourth voltage is applied to the first and second word lines, thereafter a sixth voltage lower than the fourth voltage is applied to the first selection line, and thereafter a seventh voltage is applied to the first and second word lines.
    Type: Grant
    Filed: April 30, 2020
    Date of Patent: May 17, 2022
    Assignee: KIOXIA CORPORATION
    Inventor: Hiroki Date
  • Patent number: 11238941
    Abstract: A semiconductor memory device comprises a bit line and source line, a first memory cell and first and second transistors connected therebetween, a second memory cell and third and fourth transistors connected therebetween, and first through fifth wirings connected to the first and the second memory cells and gate electrodes of the first to the fourth transistors. At a first timing of a read operation, voltages of the first through third wirings are larger than voltages of the fourth and fifth wirings. At a second timing, voltages of the second and third wirings are larger than voltages of the fourth and fifth wirings. At a third timing, voltages of the fourth and fifth wirings are larger than their voltages at the second timing. At a fourth timing, voltages of the second and third wirings are larger than a voltage of the fourth wiring.
    Type: Grant
    Filed: August 31, 2020
    Date of Patent: February 1, 2022
    Assignee: Kioxia Corporation
    Inventor: Hiroki Date
  • Publication number: 20220020428
    Abstract: A semiconductor storage device includes: a first memory cell and a second memory cell that are adjacent to each other and connected to each other in series; a first word line connected to the first memory cell; a second word line connected to the second memory cell; and a control circuit. The control circuit is configured to, in a first read operation to read a first bit stored in the first memory cell, apply a first voltage to the first word line, and then, apply a first read voltage lower than the first voltage, to the first word line, and apply a second voltage to the second word line, and then, apply a third voltage lower than the second voltage and higher than the first voltage, to the second word line. The third voltage is applied to the second word line after the first read voltage is applied to the first word line.
    Type: Application
    Filed: February 24, 2021
    Publication date: January 20, 2022
    Applicant: Kioxia Corporation
    Inventors: Hiroki DATE, Takeshi NAKANO
  • Publication number: 20210241837
    Abstract: A semiconductor memory device comprises a bit line and source line, a first memory cell and first and second transistors connected therebetween, a second memory cell and third and fourth transistors connected therebetween, and first through fifth wirings connected to the first and the second memory cells and gate electrodes of the first to the fourth transistors. At a first timing of a read operation, voltages of the first through third wirings are larger than voltages of the fourth and fifth wirings. At a second timing, voltages of the second and third wirings are larger than voltages of the fourth and fifth wirings. At a third timing, voltages of the fourth and fifth wirings are larger than their voltages at the second timing. At a fourth timing, voltages of the second and third wirings are larger than a voltage of the fourth wiring.
    Type: Application
    Filed: August 31, 2020
    Publication date: August 5, 2021
    Applicant: Kioxia Corporation
    Inventor: Hiroki DATE
  • Patent number: 10984858
    Abstract: A semiconductor storage device includes: a voltage generation circuit configured to generate a read voltage to be supplied to a selected word line to which a read-target memory cell transistor is connected and a read-pass voltage to be supplied to an adjacent word line; a word line driver configured to, when the read voltage transitions, apply the read voltage to the selected word line with a first kick voltage amount and apply the read-pass voltage to the adjacent word line with a second kick voltage amount; and a control circuit configured to set each of the first kick voltage amount and the second kick voltage amount to a voltage corresponding to an amount of the transition.
    Type: Grant
    Filed: February 10, 2020
    Date of Patent: April 20, 2021
    Assignee: Kioxia Corporation
    Inventor: Hiroki Date
  • Publication number: 20210082499
    Abstract: A semiconductor storage device includes: a voltage generation circuit configured to generate a read voltage to be supplied to a selected word line to which a read-target memory cell transistor is connected and a read-pass voltage to be supplied to an adjacent word line; a word line driver configured to, when the read voltage transitions, apply the read voltage to the selected word line with a first kick voltage amount and apply the read-pass voltage to the adjacent word line with a second kick voltage amount; and a control circuit configured to set each of the first kick voltage amount and the second kick voltage amount to a voltage corresponding to an amount of the transition.
    Type: Application
    Filed: February 10, 2020
    Publication date: March 18, 2021
    Applicant: Kioxia Corporation
    Inventor: Hiroki DATE
  • Publication number: 20200258556
    Abstract: In a semiconductor memory device, in a write operation performed to a memory cell transistor, a first voltage is applied to a first word line and a second voltage lower than the first voltage is applied to a second word line. When a command to stop is received during the write operation, a third voltage lower than the second voltage is applied to the first and second word lines, thereafter a fourth voltage higher than the third voltage is applied to a first selection line, thereon or thereafter a fifth voltage higher than the fourth voltage is applied to the first and second word lines, thereafter a sixth voltage lower than the fourth voltage is applied to the first selection line, and thereafter a seventh voltage is applied to the first and second word lines.
    Type: Application
    Filed: April 30, 2020
    Publication date: August 13, 2020
    Applicant: TOSHIBA MEMORY CORPORATION
    Inventor: Hiroki DATE
  • Patent number: 10685689
    Abstract: A semiconductor memory device includes: a substrate; a first memory transistor and a first selection transistor aligned in a first direction intersecting a surface of the substrate and connected to each other; a first wiring connected to a gate electrode of the first memory transistor; and a second wiring connected to a gate electrode of the first selection transistor. Moreover, in a write operation, at a first timing, a voltage of the first wiring rises, at a subsequent second timing, the voltage of the first wiring falls, at a subsequent third timing, a voltage of the second wiring rises, at the third timing or at a subsequent fourth timing, the voltage of the first wiring rises, at a subsequent fifth timing, the voltage of the second wiring falls, and at a subsequent sixth timing, the voltage of the first wiring falls.
    Type: Grant
    Filed: January 28, 2019
    Date of Patent: June 16, 2020
    Assignee: TOSHIBA MEMORY CORPORATION
    Inventor: Hiroki Date
  • Patent number: 10622079
    Abstract: According to one embodiment, a memory device comprises a first memory cell configured to store data, a first word line connected to the first memory cell, a first circuit configured to supply a voltage to the first word line, a second circuit configured to control the first circuit, and a sequencer configured to control the first circuit and the second circuit. The sequencer, when data is written to the first memory cell, determines whether a condition is satisfied or not. The sequencer causes the second circuit to generate a first voltage, when the sequencer determines that the condition is not satisfied, and causes the second circuit to generate a second voltage which is higher than the first voltage, when the sequencer determines that the condition is satisfied.
    Type: Grant
    Filed: July 31, 2019
    Date of Patent: April 14, 2020
    Assignee: TOSHIBA MEMORY CORPORATION
    Inventor: Hiroki Date
  • Publication number: 20200082855
    Abstract: A semiconductor memory device includes: a substrate; a first memory transistor and a first selection transistor aligned in a first direction intersecting a surface of the substrate and connected to each other; a first wiring connected to a gate electrode of the first memory transistor; and a second wiring connected to a gate electrode of the first selection transistor. Moreover, in a write operation, at a first timing, a voltage of the first wiring rises, at a subsequent second timing, the voltage of the first wiring falls, at a subsequent third timing, a voltage of the second wiring rises, at the third timing or at a subsequent fourth timing, the voltage of the first wiring rises, at a subsequent fifth timing, the voltage of the second wiring falls, and at a subsequent sixth timing, the voltage of the first wiring falls.
    Type: Application
    Filed: January 28, 2019
    Publication date: March 12, 2020
    Applicant: TOSHIBA MEMORY CORPORATION
    Inventor: Hiroki DATE
  • Publication number: 20190355430
    Abstract: According to one embodiment, a memory device comprises a first memory cell configured to store data, a first word line connected to the first memory cell, a first circuit configured to supply a voltage to the first word line, a second circuit configured to control the first circuit, and a sequencer configured to control the first circuit and the second circuit. The sequencer, when data is written to the first memory cell, determines whether a condition is satisfied or not. The sequencer causes the second circuit to generate a first voltage, when the sequencer determines that the condition is not satisfied, and causes the second circuit to generate a second voltage which is higher than the first voltage, when the sequencer determines that the condition is satisfied.
    Type: Application
    Filed: July 31, 2019
    Publication date: November 21, 2019
    Applicant: TOSHIBA MEMORY CORPORATION
    Inventor: Hiroki DATE