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).
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Publication number: 20240145006Abstract: Memory cells of a second sub-block are programmed by pre-charging channels of unselected memory cells connected to the selected word line, boosting the pre-charged channels of unselected memory cells and applying a program voltage to selected non-volatile memory cells connected to the selected word line. The pre-charging includes applying one or more overdrive voltages to word lines connected to memory cells of a first sub-block to provide a conductive path from memory cells of the second sub-block through the first sub-block to a source line and maintaining the word lines connected to memory cells of the first sub-block at one or more overdrive voltages while ramping down signals at the end of the pre-charging. Dummy word lines, positioned between sub-blocks, are maintained at a resting voltage during the boosting in order to cut-off channels of memory cells in the second sub-block from channels of memory cells in the first sub-block.Type: ApplicationFiled: July 24, 2023Publication date: May 2, 2024Applicant: SanDisk Technologies LLCInventors: Peng Zhang, Yanli Zhang, Dengtao Zhao, Jiacen Guo
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Patent number: 11972820Abstract: Memory cells are arranged as NAND strings to form a block divided into sub-blocks, and each NAND string includes a dummy memory cell connected to a dummy word line. Memory cells are programmed by applying programming pulses to a selected word line in a selected sub-block with program-verify performed between pulses. Unselected NAND strings are inhibited from programming by boosting channels of the unselected NAND strings in the selected sub-block from a positive pre-charge voltage to a boosted voltage. The pre-charging of the channels of unselected NAND strings is performed while lowering voltages at the end of program-verify by applying overdrive voltages to data word lines in a sub-block closer to the source line than the selected sub-block and lowering to a resting voltage a dummy word line between the sub-blocks prior to lowering to a resting voltage the data word lines in the sub-block closer to the source line.Type: GrantFiled: August 30, 2022Date of Patent: April 30, 2024Assignee: SanDisk Technologies LLCInventors: Jiacen Guo, Dengtao Zhao, Xiang Yang
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Patent number: 11961573Abstract: A plurality of memory programming the memory cells to at least one programmed data state in a plurality of program-verify iterations. In each iteration, after a programming pulse, a sensing operation is conducted to compare the threshold voltages of the memory cells to a low verify voltage associated with a first programmed data state and to a high very voltage associated with the first programmed data state. The sensing operation includes discharging a sense node through a bit line coupled to one of the memory cells and monitoring a discharge time of the sense node. At least one aspect of the sensing operation is temperature dependent so that a voltage gap between the high and low verify voltages is generally constant across a range of temperatures.Type: GrantFiled: November 23, 2021Date of Patent: April 16, 2024Assignee: SanDisk Technologies, LLCInventors: Abhijith Prakash, Xiang Yang, Dengtao Zhao
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Publication number: 20240105265Abstract: A non-volatile memory system comprises a plurality of non-volatile memory cells divided into three or more tiers. The memory cells can be programmed, erased and read. In order to achieve uniform erase speed for the three or more tiers, the erase process comprises applying a larger voltage bias to control gates of non-volatile memory cells in the outer tiers than the voltage bias applied to control gates of non-volatile memory cells in one or more inner tiers.Type: ApplicationFiled: September 26, 2022Publication date: March 28, 2024Applicant: SanDisk Technologies LLCInventors: Xiang Yang, Masaaki Higashitani, Abhijith Prakash, Dengtao Zhao
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Publication number: 20240079068Abstract: A storage device is disclosed herein. The storage device comprises: a non-volatile memory, where the non-volatile memory includes a block of N wordlines partitioned into a plurality of sub-blocks and the plurality of sub-blocks includes a first sub-block of a first subset of the block of N wordlines and a second sub-block of a second subset of the block of N wordlines; and control circuitry coupled to the block of N wordlines. The control circuitry is configured to: perform a program operation in a normal order programming sequence on the first sub-block; perform a sensing operation on the first sub-block using a reverse sensing scheme; perform a program operation in a reverse order programming sequence on the second sub-block; and perform a sensing operation on the second sub-block using a regular sensing scheme.Type: ApplicationFiled: September 7, 2022Publication date: March 7, 2024Applicant: SanDisk Technologies LLCInventors: Dengtao Zhao, Deepanshu Dutta, Peng Zhang, Heguang Li
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Publication number: 20240071529Abstract: Memory cells are arranged as NAND strings to form a block divided into sub-blocks, and each NAND string includes a dummy memory cell connected to a dummy word line. Memory cells are programmed by applying programming pulses to a selected word line in a selected sub-block with program-verify performed between pulses. Unselected NAND strings are inhibited from programming by boosting channels of the unselected NAND strings in the selected sub-block from a positive pre-charge voltage to a boosted voltage. The pre-charging of the channels of unselected NAND strings is performed while lowering voltages at the end of program-verify by applying overdrive voltages to data word lines in a sub-block closer to the source line than the selected sub-block and lowering to a resting voltage a dummy word line between the sub-blocks prior to lowering to a resting voltage the data word lines in the sub-block closer to the source line.Type: ApplicationFiled: August 30, 2022Publication date: February 29, 2024Applicant: SanDisk Technologies LLCInventors: Jiacen Guo, Dengtao Zhao, Xiang Yang
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Publication number: 20240055059Abstract: Non-volatile memory cells are programmed by pre-charging channels of unselected non-volatile memory cells connected to a selected data word line, boosting the channels of unselected non-volatile memory cells connected to the selected data word line after the pre-charging and applying a program voltage pulse to selected non-volatile memory cells connected to the selected data word line while boosting. The pre-charging includes applying pre-charge voltages to one set of data word lines and dummy word line(s) as well as applying overdrive voltages to another set of data word lines connected to already programmed memory cells. At the end of the pre-charging, the dummy word lines are ramped down to a resting voltage prior to lowering the data word lines to one or more resting voltages.Type: ApplicationFiled: August 10, 2022Publication date: February 15, 2024Applicant: SanDisk Technologies LLCInventors: Jiacen Guo, Dengtao Zhao, Xiang Yang
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Patent number: 11894071Abstract: A system has been described that performs differential temperature compensation based on a differential between the temperature at time of programming and temperature at time of reading for a set of data. Differential temperature compensation is useful for bulk programming/reading (e.g., many pages of data) and/or programming/reading super pages of data (multiple pages residing on different memory die).Type: GrantFiled: December 13, 2021Date of Patent: February 6, 2024Assignee: SanDisk Technologies LLCInventors: Yi Song, Dengtao Zhao, Sarath Puthenthermadam, Jiahui Yuan
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Patent number: 11791001Abstract: A memory system reads data from non-volatile memory cells using a set of read compare voltages to determine which data state the memory cells are in, where each data state is associated with predetermined data values. The read compare voltages are determined dynamically based on a difference between memory cell current at time of programming and memory cell current at time of reading.Type: GrantFiled: March 21, 2022Date of Patent: October 17, 2023Assignee: SANDISK TECHNOLOGIES LLCInventors: Yi Song, Jiahui Yuan, Dengtao Zhao
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Publication number: 20230298678Abstract: A memory system reads data from non-volatile memory cells using a set of read compare voltages to determine which data state the memory cells are in, where each data state is associated with predetermined data values. The read compare voltages are determined dynamically based on a difference between memory cell current at time of programming and memory cell current at time of reading.Type: ApplicationFiled: March 21, 2022Publication date: September 21, 2023Applicant: SANDISK TECHNOLOGIES LLCInventors: Yi Song, Jiahui Yuan, Dengtao Zhao
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Patent number: 11688469Abstract: To help reduce program disturbs in non-selected NAND strings of a non-volatile memory, a sub-block based boosting scheme in introduced. For a three dimensional NAND memory structure, in which the memory cells above a joint region form an upper sub-block and memory cells below the joint region form a lower sub-block, dummy word lines in the joint region act as select gates to allow boosting at the sub-block level when the lower block is being programmed in a reverse order.Type: GrantFiled: August 11, 2021Date of Patent: June 27, 2023Assignee: SanDisk Technologies LLCInventors: Dengtao Zhao, Gerrit Jan Hemink, Xiang Yang, Ken Oowada, Guirong Liang
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Publication number: 20230197168Abstract: A system has been described that performs differential temperature compensation based on a differential between the temperature at time of programming and temperature at time of reading for a set of data. Differential temperature compensation is useful for bulk programming/reading (e.g., many pages of data) and/or programming/reading super pages of data (multiple pages residing on different memory die).Type: ApplicationFiled: December 13, 2021Publication date: June 22, 2023Applicant: SanDisk Technologies LLCInventors: Yi Song, Dengtao Zhao, Sarath Puthenthermadam, Jiahui Yuan
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Publication number: 20230186996Abstract: A system has been described that performs differential temperature compensation based on a differential between the temperature at time of programming and temperature at time of reading for a set of data. Differential temperature compensation is useful for bulk programming/reading (e.g., many pages of data) and/or programming/reading super pages of data (multiple pages residing on different memory die).Type: ApplicationFiled: December 13, 2021Publication date: June 15, 2023Applicant: SanDisk Technologies LLCInventors: Yi Song, Dengtao Zhao, Sarath Puthenthermadam, Jiahui Yuan
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Patent number: 11646081Abstract: Technology is provided for extending the useful life of a block of memory cells by changing an operating parameter in a physical region of the block that is more susceptible to wear than other regions. Changing the operating parameter in the physical region extends the life of that region, which extends the life of the block. The operating parameter may be, for example, a program voltage step size or a storage capacity of the memory cells. For example, using a smaller program voltage step size in a sub-block that is more susceptible to wear extends the life of that sub-block, which extends the life of the block. For example, programming memory cells to fewer bits per cell in the region of the block (e.g., sub-block, word line) that is more susceptible to wear extends the useful life of that region, which extends the life of the block.Type: GrantFiled: August 3, 2021Date of Patent: May 9, 2023Assignee: SanDisk Technologies LLCInventors: Xiang Yang, Peter Rabkin, Henry Chin, Ken Oowada, Dengtao Zhao, Gerrit Jan Hemink
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Publication number: 20230050955Abstract: To help reduce program disturbs in non-selected NAND strings of a non-volatile memory, a sub-block based boosting scheme in introduced. For a three dimensional NAND memory structure, in which the memory cells above a joint region form an upper sub-block and memory cells below the joint region form a lower sub-block, dummy word lines in the joint region act as select gates to allow boosting at the sub-block level when the lower block is being programmed in a reverse order.Type: ApplicationFiled: August 11, 2021Publication date: February 16, 2023Applicant: SanDisk Technologies LLCInventors: Dengtao Zhao, Gerrit Jan Hemink, Xiang Yang, Ken Oowada, Guirong Liang
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Publication number: 20230041476Abstract: Technology is provided for extending the useful life of a block of memory cells by changing an operating parameter in a physical region of the block that is more susceptible to wear than other regions. Changing the operating parameter in the physical region extends the life of that region, which extends the life of the block. The operating parameter may be, for example, a program voltage step size or a storage capacity of the memory cells. For example, using a smaller program voltage step size in a sub-block that is more susceptible to wear extends the life of that sub-block, which extends the life of the block. For example, programming memory cells to fewer bits per cell in the region of the block (e.g., sub-block, word line) that is more susceptible to wear extends the useful life of that region, which extends the life of the block.Type: ApplicationFiled: August 3, 2021Publication date: February 9, 2023Applicant: SanDisk Technologies LLCInventors: Xiang Yang, Peter Rabkin, Henry Chin, Ken Oowada, Dengtao Zhao, Gerrit Jan Hemink
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Patent number: 11574693Abstract: 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: GrantFiled: June 15, 2021Date of Patent: February 7, 2023Assignee: SanDisk Technologies LLCInventors: Chin-Yi Chen, Muhammad Masuduzzaman, Dengtao Zhao, Anubhav Khandelwal, Ravi Kumar
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Patent number: 11568943Abstract: 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: GrantFiled: November 24, 2020Date of Patent: January 31, 2023Assignee: SanDisk Technologies LLCInventors: Xue Bai Pitner, Dengtao Zhao, Deepanshu Dutta, Ravi Kumar
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Patent number: 11557358Abstract: 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: GrantFiled: April 15, 2021Date of Patent: January 17, 2023Assignee: SanDisk Technologies LLCInventors: Dengtao Zhao, Deepanshu Dutta, Ravi Kumar
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Patent number: 11551765Abstract: 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: GrantFiled: May 25, 2021Date of Patent: January 10, 2023Assignee: SANDISK TECHNOLOGIES LLCInventors: Xiang Yang, Dengtao Zhao