Patents by Inventor Dengtao Zhao

Dengtao Zhao 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: 20220399066
    Abstract: A memory apparatus and method of operation are provided. The apparatus includes memory cells connected to one of a plurality of word lines and arranged in strings and configured to retain a threshold voltage corresponding to one of a plurality of memory states. A control circuit is coupled to the plurality of word lines and strings and is configured to erase the memory cells using a stripe erase operation in response to determining a cycle count is less than a predetermined cycle count maximum threshold. The control circuit is also configured to perform a dummy cycle operation in response to determining the cycle count is not less than the predetermined cycle count maximum threshold.
    Type: Application
    Filed: June 15, 2021
    Publication date: December 15, 2022
    Applicant: SanDisk Technologies LLC
    Inventors: Chin-Yi Chen, Muhammad Masuduzzaman, Dengtao Zhao, Anubhav Khandelwal, Ravi Kumar
  • Publication number: 20220383956
    Abstract: A non-volatile memory system adjusts the speed of a memory operation for a subset of non-volatile memory cells. For example, during a GIDL based erase process, the GIDL generation can be dampened for a subset of memory cells (e.g., for a set of NAND strings, or one or more sub-blocks).
    Type: Application
    Filed: May 25, 2021
    Publication date: December 1, 2022
    Applicant: SANDISK TECHNOLOGIES LLC
    Inventors: Xiang Yang, Dengtao Zhao
  • Publication number: 20220375524
    Abstract: A nonvolatile memory control method includes a step of writing, repeatedly to a nonvolatile memory cells. The method continues with detecting when writing reaches a writing threshold value. Upon reaching the writing threshold, the method continues with driving a charge to at least one parasitic area intermediate at least two charge storage areas of the nonvolatile memory cells to improve data retention in at least one of the at least two charge storage areas of the nonvolatile memory cells.
    Type: Application
    Filed: May 18, 2021
    Publication date: November 24, 2022
    Applicant: SanDisk Technologies LLC
    Inventors: Dengtao Zhao, Ravi Kumar, Chin-Yi Chen, Ryohei Shoji
  • Patent number: 11508440
    Abstract: A nonvolatile memory control method includes a step of writing, repeatedly to a nonvolatile memory cells. The method continues with detecting when writing reaches a writing threshold value. Upon reaching the writing threshold, the method continues with driving a charge to at least one parasitic area intermediate at least two charge storage areas of the nonvolatile memory cells to improve data retention in at least one of the at least two charge storage areas of the nonvolatile memory cells.
    Type: Grant
    Filed: May 18, 2021
    Date of Patent: November 22, 2022
    Assignee: SanDisk Technologies LLC
    Inventors: Dengtao Zhao, Ravi Kumar, Chin-Yi Chen, Ryohei Shoji
  • Publication number: 20220336029
    Abstract: A memory apparatus and method of operation is provided. The apparatus includes memory cells connected to word lines and bit lines and arranged in strings and configured to retain a threshold voltage. Each of the memory cells is configured to be erased in an erase operation occurring during an erase time period. A control circuit is configured to adjust at least a portion of the erase time period in response to determining the erase operation is a segmented erase operation and is resumed after being suspended. The control circuit applies an erase signal having a plurality of voltage segments temporally separated from one another during the erase time period to each of the strings while simultaneously applying a word line erase voltage to selected ones of the word lines to encourage erasing of the memory cells coupled to the selected ones of the word lines in the segmented erase operation.
    Type: Application
    Filed: April 15, 2021
    Publication date: October 20, 2022
    Applicant: SanDisk Technologies LLC
    Inventors: Dengtao Zhao, Deepanshu Dutta, Ravi Kumar
  • Patent number: 11423993
    Abstract: A method reading memory using bi-directional sensing, including programming first memory cells coupled to a first word-line using a normal programming order; programming second memory cells coupled to a second word-line using a normal programming order; reading data from the first memory cells by applying a normal sensing operation to the first word-line; and reading data from the second memory cells by applying a reverse sensing operation to the second word-line. Methods also include receiving an error associated with reading data from the first memory cells; and then reading the data from the first memory cells by applying a reverse sensing operation to the first word-line. Method also include receiving an error associated with reading the data from the second memory cells; and then reading the data from the second memory cells by applying a normal sensing operation to the second word-line.
    Type: Grant
    Filed: November 6, 2019
    Date of Patent: August 23, 2022
    Assignee: SanDisk Technologies LLC
    Inventors: Zhiping Zhang, Muhammad Masuduzzaman, Huai-Yuan Tseng, Peng Zhang, Dengtao Zhao, Deepanshu Dutta
  • Publication number: 20220165341
    Abstract: A memory apparatus and method of operation is provided. The apparatus includes a block of memory cells. Each of the memory cells is connected to one of a plurality of word lines and are also arranged in strings and configured to retain a threshold voltage within a common range of threshold voltages. A control circuit coupled to the plurality of word lines and the strings is configured to determine an erase upper tail voltage of a distribution of the threshold voltage of the memory cells following an erase operation. The erase upper tail voltage corresponds to a cycling condition of the memory cells. The control circuit is also configured to calculate a program voltage to apply to each of selected ones of the plurality of word lines associated with the memory cells to program the memory cells during a program operation based on the erase upper tail voltage.
    Type: Application
    Filed: November 24, 2020
    Publication date: May 26, 2022
    Applicant: SanDisk Technologies LLC
    Inventors: Xue Bai Pitner, Dengtao Zhao, Deepanshu Dutta, Ravi Kumar
  • Patent number: 11315648
    Abstract: An apparatus includes a memory controller configured to apply selected one or ones of the program verify voltage levels to a single tier of memory cells. A memory controller is configured to: program data into the plurality of memory cells; and perform a program verify operation across multiple voltage levels with a first voltage level of the program verify operation being applied to a single tier that represents all of the tiers in the memory group and a second voltage level of the program verify operation being applied to multiple tiers, wherein the first voltage level is less than the second voltage level. In embodiments, less than all of the tiers, e.g., two or four tiers, can be used in the program verify to represent all of the tires.
    Type: Grant
    Filed: June 29, 2020
    Date of Patent: April 26, 2022
    Assignee: SanDisk Technologies LLC
    Inventors: Yu-Chung Lien, Dengtao Zhao, Huai-Yuan Tseng
  • Patent number: 11244735
    Abstract: A method for memory program verification includes performing a write operation on memory cells of a memory device. The method also includes identifying memory strings associated with respective memory cells of the memory cells. The method also includes identifying a first memory string of the memory strings. The method also includes disabling a portion of a write verification for the first memory string. The method also includes enabling the portion of the write verification for other memory strings of the memory strings. The method also includes performing at least the portion of the write verification operation on write verification enabled memory strings.
    Type: Grant
    Filed: February 18, 2020
    Date of Patent: February 8, 2022
    Assignee: SanDisk Technologies LLC
    Inventors: Zhiping Zhang, Huai-Yuan Tseng, Dengtao Zhao, Deepanshu Dutta
  • Publication number: 20210407603
    Abstract: An apparatus includes a memory controller configured to apply selected one or ones of the program verify voltage levels to a single tier of memory cells. A memory controller is configured to: program data into the plurality of memory cells; and perform a program verify operation across multiple voltage levels with a first voltage level of the program verify operation being applied to a single tier that represents all of the tiers in the memory group and a second voltage level of the program verify operation being applied to multiple tiers, wherein the first voltage level is less than the second voltage level. In embodiments, less than all of the tiers, e.g.
    Type: Application
    Filed: June 29, 2020
    Publication date: December 30, 2021
    Applicant: SanDisk Technologies LLC
    Inventors: Yu-Chung Lien, Dengtao Zhao, Huai-Yuan Tseng
  • Patent number: 11201111
    Abstract: A three-dimensional memory device includes an alternating stack of insulating layers and electrically conductive layers located over a substrate, where the electrically conductive layers comprise word lines located between a source select gate electrode and a drain select gate electrode, a memory opening vertically extending through each layer of the alternating stack to a top surface of the substrate, a memory film and vertical semiconductor channel having a doping of a first conductivity type located in the memory opening, and an active region having a doping of a second conductivity type that is an opposite of the first conductivity type and adjoined to an end portion of the vertical semiconductor channel to provide a p-n junction. The end portion of the vertical semiconductor channel has a first thickness, and a middle portion of the vertical semiconductor channel has a second thickness which is less than the first thickness.
    Type: Grant
    Filed: November 27, 2019
    Date of Patent: December 14, 2021
    Assignee: SANDISK TECHNOLOGIES LLC
    Inventors: Dengtao Zhao, Zhiping Zhang, Peng Zhang, Deepanshu Dutta
  • Patent number: 11107540
    Abstract: Techniques for reducing program disturb of memory cells which are formed in a NAND string extending in a lower tier and an upper tier of a stack, the lower tier including a first plurality of memory cells and the upper tier including a second plurality of memory cells, wherein each memory cell of the first and second pluralities of memory cells is connected to a respective word line. The NAND string includes a joint region formed of a dielectric material and disposed between the lower tier and the upper tier of the stack; a first non-data memory cell adjacent to and below the joint region; a second non-data memory cell adjacent to and above the joint region; and a conductive gate connected to the first non-data memory cell and the second non-data memory cell.
    Type: Grant
    Filed: February 14, 2020
    Date of Patent: August 31, 2021
    Assignee: Sandisk Technologies LLC
    Inventors: Jayavel Pachamuthu, Dengtao Zhao
  • Publication number: 20210257035
    Abstract: Techniques for reducing program disturb of memory cells which are formed in a NAND string extending in a lower tier and an upper tier of a stack, the lower tier comprising a first plurality of memory cells and the upper tier comprising a second plurality of memory cells, wherein each memory cell of the first and second pluralities of memory cells is connected to a respective word line. The NAND string includes a joint region formed of a dielectric material and disposed between the lower tier and the upper tier of the stack; a first non-data memory cell adjacent to and below the joint region; a second non-data memory cell adjacent to and above the joint region; and a conductive gate connected to the first non-data memory cell and the second non-data memory cell.
    Type: Application
    Filed: February 14, 2020
    Publication date: August 19, 2021
    Inventors: Jayavel Pachamuthu, Dengtao Zhao
  • Publication number: 20210257037
    Abstract: A method for memory program verification includes performing a write operation on memory cells of a memory device. The method also includes identifying memory strings associated with respective memory cells of the memory cells. The method also includes identifying a first memory string of the memory strings. The method also includes disabling a portion of a write verification for the first memory string. The method also includes enabling the portion of the write verification for other memory strings of the memory strings. The method also includes performing at least the portion of the write verification operation on write verification enabled memory strings.
    Type: Application
    Filed: February 18, 2020
    Publication date: August 19, 2021
    Applicant: SanDisk Technologies LLC
    Inventors: Zhiping Zhang, Huai-Yuan Tseng, Dengtao Zhao, Deepanshu Dutta
  • Patent number: 11081184
    Abstract: A method of concurrently programming a memory. Various methods include: applying a non-negative voltage on a first bit line coupled to a first memory cell; applying a negative voltage on a second bit line coupled to a second memory cell, where the negative voltage is generated using triple-well technology; then applying a programming pulse to the first and second memory cells concurrently; and in response, programming the first and second memory cells to different states. The methods also include applying a quick pass write operation to the first and second memory cells, by: applying a quick pass write voltage to the first bit line coupled to the first memory cell, where the quick pass write voltage is higher than the non-negative voltage; applying a negative quick pass write voltage to the second bit line coupled to the first memory cell, where the negative quick pass write voltage is generated using triple-well technology.
    Type: Grant
    Filed: December 3, 2019
    Date of Patent: August 3, 2021
    Assignee: SanDisk Technologies LLC
    Inventors: Zhiping Zhang, Muhammad Masuduzzaman, Huai-Yuan Tseng, Dengtao Zhao, Deepanshu Dutta
  • Patent number: 11062780
    Abstract: Method(s) and structure(s) for a two-page read operation are described and provide a multiple page read. The two page read operation provides for reading two pages with in a block without reducing the control gates to a low voltage level. The two page read can read the first page using an incrementing voltage level at discrete steps and starting the second page read at the high state for the control gates from the first page read. The second page read then decrements the control gate voltages level through the steps. This should reduce energy consumption. The two-page read operation will also reduce the time as the time period to reset the control gates to a low state are not required in between the page read operations.
    Type: Grant
    Filed: December 30, 2019
    Date of Patent: July 13, 2021
    Inventors: Zhiping Zhang, Huai-Yuan Tseng, Jiahui Yuan, Dengtao Zhao, Deepanshu Dutta
  • Publication number: 20210202011
    Abstract: Method(s) and structure(s) for a two-page read operation are described and provide a multiple page read. The two page read operation provides for reading two pages with in a block without reducing the control gates to a low voltage level. The two page read can read the first page using an incrementing voltage level at discrete steps and starting the second page read at the high state for the control gates from the first page read. The second page read then decrements the control gate voltages level through the steps. This should reduce energy consumption. The two-page read operation will also reduce the time as the time period to reset the control gates to a low state are not required in between the page read operations.
    Type: Application
    Filed: December 30, 2019
    Publication date: July 1, 2021
    Applicant: SanDisk Technologies LLC
    Inventors: Zhiping Zhang, Huai-Yuan Tseng, Jiahui Yuan, Dengtao Zhao, Deepanshu Dutta
  • Publication number: 20210159169
    Abstract: A three-dimensional memory device includes an alternating stack of insulating layers and electrically conductive layers located over a substrate, where the electrically conductive layers comprise word lines located between a source select gate electrode and a drain select gate electrode, a memory opening vertically extending through each layer of the alternating stack to a top surface of the substrate, a memory film and vertical semiconductor channel having a doping of a first conductivity type located in the memory opening, and an active region having a doping of a second conductivity type that is an opposite of the first conductivity type and adjoined to an end portion of the vertical semiconductor channel to provide a p-n junction. The end portion of the vertical semiconductor channel has a first thickness, and a middle portion of the vertical semiconductor channel has a second thickness which is less than the first thickness.
    Type: Application
    Filed: November 27, 2019
    Publication date: May 27, 2021
    Inventors: Dengtao ZHAO, Zhiping ZHANG, Peng ZHANG, Deepanshu DUTTA
  • Publication number: 20210134372
    Abstract: A method reading memory using bi-directional sensing, including programming first memory cells coupled to a first word-line using a normal programming order; programming second memory cells coupled to a second word-line using a normal programming order; reading data from the first memory cells by applying a normal sensing operation to the first word-line; and reading data from the second memory cells by applying a reverse sensing operation to the second word-line. Methods also include receiving an error associated with reading data from the first memory cells; and then reading the data from the first memory cells by applying a reverse sensing operation to the first word-line. Method also include receiving an error associated with reading the data from the second memory cells; and then reading the data from the second memory cells by applying a normal sensing operation to the second word-line.
    Type: Application
    Filed: November 6, 2019
    Publication date: May 6, 2021
    Applicant: SanDisk Technologies LLC
    Inventors: Zhiping Zhang, Muhammad Masuduzzaman, Huai-Yuan Tseng, Peng Zhang, Dengtao Zhao, Deepanshu Dutta
  • Publication number: 20210134370
    Abstract: A method of concurrently programming a memory. Various methods include: applying a non-negative voltage on a first bit line coupled to a first memory cell; applying a negative voltage on a second bit line coupled to a second memory cell, where the negative voltage is generated using triple-well technology; then applying a programming pulse to the first and second memory cells concurrently; and in response, programming the first and second memory cells to different states. The methods also include applying a quick pass write operation to the first and second memory cells, by: applying a quick pass write voltage to the first bit line coupled to the first memory cell, where the quick pass write voltage is higher than the non-negative voltage; applying a negative quick pass write voltage to the second bit line coupled to the first memory cell, where the negative quick pass write voltage is generated using triple-well technology.
    Type: Application
    Filed: December 3, 2019
    Publication date: May 6, 2021
    Applicant: SanDisk Technologies LLC
    Inventors: Zhiping Zhang, Muhammad Masuduzzaman, Huai-Yuan Tseng, Dengtao Zhao, Deepanshu Dutta