Patents by Inventor Osamu Nagao

Osamu Nagao 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: 11810642
    Abstract: A memory device includes: a memory cell array; a first latch; a second latch; a first circuit; and a second circuit. The memory cell array includes first, second, and third columns associated with first, second, and third addresses, respectively. The first latch stores the first address and is associated with a fourth address. The second latch stores the second address and is associated with a fifth address. The fourth address and the fifth address are in an ascending order. The first circuit selects the third column in place of the first column based on the first address. The second circuit determines whether or not the first address and the second address are in an ascending order.
    Type: Grant
    Filed: March 4, 2022
    Date of Patent: November 7, 2023
    Assignee: Kioxia Corporation
    Inventor: Osamu Nagao
  • Publication number: 20230042340
    Abstract: A memory device includes: a memory cell array; a first latch; a second latch; a first circuit; and a second circuit. The memory cell array includes first, second, and third columns associated with first, second, and third addresses, respectively. The first latch stores the first address and is associated with a fourth address. The second latch stores the second address and is associated with a fifth address. The fourth address and the fifth address are in an ascending order. The first circuit selects the third column in place of the first column based on the first address. The second circuit determines whether or not the first address and the second address are in an ascending order.
    Type: Application
    Filed: March 4, 2022
    Publication date: February 9, 2023
    Applicant: Kioxia Corporation
    Inventor: Osamu NAGAO
  • Patent number: 11514984
    Abstract: A semiconductor memory device comprises a first word line coupled to first and second memory cell transistors, first and second bit lines, and a controller. In a first program loop, a controller applies a first voltage to first and second bit lines in a program operation, and classifies the first and second memory cell transistors into first and second groups by applying a first verify voltage to the first word line in a verify operation. In a program operation of each of program loops that are executed after the first program loop, the controller applies the first voltage to the first bit line when a verification of the first memory cell transistor has not been passed, and applies a second voltage to the second bit line when a verification of the second memory cell transistor has not been passed.
    Type: Grant
    Filed: September 11, 2020
    Date of Patent: November 29, 2022
    Assignee: KIOXIA CORPORATION
    Inventor: Osamu Nagao
  • Patent number: 11164645
    Abstract: A semiconductor memory device includes memory cells, a word line, and a controller. The controller is configured to: execute a first program operation in which a first program voltage is applied to the word line; execute a second program operation in which the first program voltage is applied to the word line, when a resumed first verify operation ends; and execute a third program operation in which a second program voltage higher than the first program voltage is applied to the word line, after a resumed second verify operation.
    Type: Grant
    Filed: March 10, 2021
    Date of Patent: November 2, 2021
    Assignee: KIOXIA CORPORATION
    Inventor: Osamu Nagao
  • Publication number: 20210193240
    Abstract: A semiconductor memory device according to an embodiment includes memory cells, a word line, and a controller. The controller is configured to: execute a first program operation in which a first program voltage is applied to the word line; execute a second program operation in which the first program voltage is applied to the word line, when a resumed first verify operation ends; and execute a third program operation in which a second program voltage higher than the first program voltage is applied to the word line, after a resumed second verify operation.
    Type: Application
    Filed: March 10, 2021
    Publication date: June 24, 2021
    Applicant: Kioxia Corporation
    Inventor: Osamu NAGAO
  • Patent number: 10978166
    Abstract: A semiconductor memory device includes memory cells, a word line, and a controller. The controller is configured to: execute a first program operation in which a first program voltage is applied to the word line; execute a second program operation in which the first program voltage is applied to the word line, when a resumed first verify operation ends; and execute a third program operation in which a second program voltage higher than the first program voltage is applied to the word line, after a resumed second verify operation.
    Type: Grant
    Filed: January 28, 2020
    Date of Patent: April 13, 2021
    Assignee: KIOXIA CORPORATION
    Inventor: Osamu Nagao
  • Publication number: 20210104286
    Abstract: A semiconductor memory device according to an embodiment includes memory cells, a word line, and a controller. The controller is configured to: execute a first program operation in which a first program voltage is applied to the word line; execute a second program operation in which the first program voltage is applied to the word line, when a resumed first verify operation ends; and execute a third program operation in which a second program voltage higher than the first program voltage is applied to the word line, after a resumed second verify operation.
    Type: Application
    Filed: January 28, 2020
    Publication date: April 8, 2021
    Applicant: KIOXIA CORPORATION
    Inventor: Osamu NAGAO
  • Publication number: 20210090642
    Abstract: A semiconductor memory device comprises a first word line coupled to first and second memory cell transistors, first and second bit lines, and a controller. In a first program loop, a controller applies a first voltage to first and second bit lines in a program operation, and classifies the first and second memory cell transistors into first and second groups by applying a first verify voltage to the first word line in a verify operation. In a program operation of each of program loops that are executed after the first program loop, the controller applies the first voltage to the first bit line when a verification of the first memory cell transistor has not been passed, and applies a second voltage to the second bit line when a verification of the second memory cell transistor has not been passed.
    Type: Application
    Filed: September 11, 2020
    Publication date: March 25, 2021
    Applicant: Kioxia Corporation
    Inventor: Osamu NAGAO
  • Patent number: 10249377
    Abstract: According to one embodiment, a semiconductor memory device includes a memory cell, a bit line, a sense amplifier, a word line, and a row decoder. A write operation repeats a program loop including a program operation, first and second verify operations. The row decoder applies a first read voltage to the word line in the first and second verify operations. When the write operation is not suspended, the sense amplifier senses a voltage of the bit line for a first sense period in the first verify operation. When the write operation is suspended, the sense amplifier senses the voltage of the bit line for a second sense period shorter than the first sense period in the initial first verify operation after a resumption of the write operation.
    Type: Grant
    Filed: September 11, 2017
    Date of Patent: April 2, 2019
    Assignee: TOSHIBA MEMORY CORPORATION
    Inventors: Hayao Kasai, Osamu Nagao, Mitsuaki Honma, Yoshikazu Harada, Akio Sugahara
  • Patent number: 10109355
    Abstract: A semiconductor memory device includes a memory cell array having a plurality of memory cell groups, the memory cell groups including a first memory group including first memory cells, and a control circuit configured to execute a first write operation targeting the first memory cells in a first mode in which the control circuit executes at least a first programming operation on the first memory cells followed by a multiple number of first verification operations to verify the first programming operation, and then in a second mode, in which the control circuit executes a second programming operation on the first memory cells followed by a second verification operation to verify the second programming operation. A programming voltage applied during the second programming operation is less than a programming voltage applied during the first programming operation, and is adjusted based on a number of first verification operations.
    Type: Grant
    Filed: September 4, 2017
    Date of Patent: October 23, 2018
    Assignee: TOSHIBA MEMORY CORPORATION
    Inventor: Osamu Nagao
  • Publication number: 20180261291
    Abstract: A semiconductor memory device includes a memory cell array having a plurality of memory cell groups, the memory cell groups including a first memory group including first memory cells, and a control circuit configured to execute a first write operation targeting the first memory cells in a first mode in which the control circuit executes at least a first programming operation on the first memory cells followed by a multiple number of first verification operations to verify the first programming operation, and then in a second mode, in which the control circuit executes a second programming operation on the first memory cells followed by a second verification operation to verify the second programming operation. A programming voltage applied during the second programming operation is less than a programming voltage applied during the first programming operation, and is adjusted based on a number of first verification operations.
    Type: Application
    Filed: September 4, 2017
    Publication date: September 13, 2018
    Inventor: Osamu NAGAO
  • Publication number: 20180247695
    Abstract: According to one embodiment, a semiconductor memory device includes a memory cell, a bit line, a sense amplifier, a word line, and a row decoder. A write operation repeats a program loop including a program operation, first and second verify operations. The row decoder applies a first read voltage to the word line in the first and second verify operations. When the write operation is not suspended, the sense amplifier senses a voltage of the bit line for a first sense period in the first verify operation. When the write operation is suspended, the sense amplifier senses the voltage of the bit line for a second sense period shorter than the first sense period in the initial first verify operation after a resumption of the write operation.
    Type: Application
    Filed: September 11, 2017
    Publication date: August 30, 2018
    Applicant: TOSHIBA MEMORY CORPORATION
    Inventors: Hayao KASAI, Osamu NAGAO, Mitsuaki HONMA, Yoshikazu HARADA, Akio SUGAHARA
  • Patent number: 9003105
    Abstract: According to one embodiment, a semiconductor memory device includes a plurality of blocks in a memory cell, each of the blocks acting as an erasure unit of data, the block including a plurality of pages, each of the pages including a plurality of memory cell transistors, each of the memory cell transistors being configured to be an erasure state or a first retention state based on a threshold voltage of the memory cell transistor, and a controller searching data in the block with respect to, writing a first flag denoting effective into a prescribed page of the block with the erasure state, and writing the first flag denoting non-effective into a prescribed page of the block with the first retention state, reading out the prescribed page of the block with the first retention state, and determining that the block is writable when the first flag denotes effective.
    Type: Grant
    Filed: September 5, 2012
    Date of Patent: April 7, 2015
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Ayako Yamano, Teruo Takagiwa, Koichi Fukuda, Hitoshi Shiga, Osamu Nagao
  • Patent number: 8830760
    Abstract: A memory includes memory cells and a sense amplifier including a sense node that transmits a voltage according to a current flowing in one of the memory cells and detects logic of data based on the voltage of the sense node. A write sequence of writing data in a selected cell is performed by repeating write loops each including a write stage of writing data in the selected cell and a verify read stage of verifying that the data has been written in the selected cell by performing discharge from the sense node through the selected cell. The sense amplifier changes, according to a logic of data detected at the verify read stage in a first write loop, a period of discharge from the sense node to the selected cell at the verify read stage in a second write loop following the first write loop.
    Type: Grant
    Filed: February 20, 2013
    Date of Patent: September 9, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Rieko Funatsuki, Osamu Nagao
  • Publication number: 20140050028
    Abstract: A memory includes memory cells and a sense amplifier including a sense node that transmits a voltage according to a current flowing in one of the memory cells and detects logic of data based on the voltage of the sense node. A write sequence of writing data in a selected cell is performed by repeating write loops each including a write stage of writing data in the selected cell and a verify read stage of verifying that the data has been written in the selected cell by performing discharge from the sense node through the selected cell. The sense amplifier changes, according to a logic of data detected at the verify read stage in a first write loop, a period of discharge from the sense node to the selected cell at the verify read stage in a second write loop following the first write loop.
    Type: Application
    Filed: February 20, 2013
    Publication date: February 20, 2014
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Rieko FUNATSUKI, Osamu Nagao
  • Publication number: 20130246730
    Abstract: According to one embodiment, a semiconductor memory device includes a plurality of blocks in a memory cell, each of the blocks acting as an erasure unit of data, the block including a plurality of pages, each of the pages including a plurality of memory cell transistors, each of the memory cell transistors being configured to be an erasure state or a first retention state based on a threshold voltage of the memory cell transistor, and a controller searching data in the block with respect to, writing a first flag denoting effective into a prescribed page of the block with the erasure state, and writing the first flag denoting non-effective into a prescribed page of the block with the first retention state, reading out the prescribed page of the block with the first retention state, and determining that the block is writable when the first flag denotes effective.
    Type: Application
    Filed: September 5, 2012
    Publication date: September 19, 2013
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Ayako YAMANO, Teruo Takagiwa, Koichi Fukuda, Hitoshi Shiga, Osamu Nagao
  • Patent number: 8482985
    Abstract: A nonvolatile semiconductor storage device according to an embodiment includes an erase circuit executing an erase sequence, wherein in the erase sequence, the erase circuit executes: an erase operation to change a selection memory cell group to an erased state, after the erase operation, a soft program operation on the selection memory cell group to solve over-erased state, and after the soft program operation, a first soft program verification operation performed on at least one partial selection memory cell group of a first partial selection memory cell group and a second partial selection memory cell group so as to confirm whether the partial selection memory cell group includes a predetermined number of memory cells or more that have threshold values equal to or more than a predetermined first threshold value, and after the first soft program verification operation.
    Type: Grant
    Filed: December 9, 2011
    Date of Patent: July 9, 2013
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Ayako Yamano, Osamu Nagao, Toshiaki Edahiro
  • Publication number: 20130070546
    Abstract: A nonvolatile semiconductor memory device according to the embodiment comprises a memory cell array including plural blocks arranged in a first direction, each block containing plural memory cells operative to store data; a row decoder including a faulty block information holder circuit operative to store faulty block information indicative that the block is a faulty block; and a faulty block detector circuit operative to, when each of block groups includes at least one of the plural blocks, subject one of the block groups to a first detection step of simultaneously and intensively referring to pieces of faulty block information respectively corresponding to the plural blocks in one of the block groups simultaneously to detect whether the block group contains a faulty block.
    Type: Application
    Filed: March 19, 2012
    Publication date: March 21, 2013
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Osamu Nagao, Hitoshi Shiga
  • Patent number: 8339866
    Abstract: A NAND type flash memory for erasing data every block including plural memory cell transistors that are provided every block and have floating gates formed through first gate insulating film above a well formed in a semiconductor substrate and control gates formed through second gate insulating film above the floating gates, data in the memory cell transistors being rewritable by controlling charge amounts accumulated in the floating gates, and a row decoder having a plurality of MOS transistors having drains that are respectively connected to corresponding word lines connected to the control gates of the plurality of memory cell transistors, the row decoder controlling gate and source voltages of the MOS transistors.
    Type: Grant
    Filed: September 30, 2009
    Date of Patent: December 25, 2012
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Akihiro Imamoto, Osamu Nagao
  • Patent number: 8320187
    Abstract: According to one embodiment, a nonvolatile semiconductor memory includes memory cells storing data of multi-level, a bit scan circuit to scan the number of to-be-written memory cells and the number of memory cells that have passed the verify, a processing unit to perform an operation process based on a scan result of the bit scan circuit, and a control circuit to control an operation of writing data according to a first mode in which a voltage used for an upper-data writing is calculated during a lower-data writing and a second mode used a voltage based on setting information. The bit scan circuit scans the number of to-be-written memory cells before starting writing and the processing unit compares the number of to-be-written memory cells with a criterion and determines one of the first and second modes for the writing based on a result of comparison.
    Type: Grant
    Filed: September 16, 2011
    Date of Patent: November 27, 2012
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Osamu Nagao