Memory device with compensation for program speed variations due to block oxide thinning

    公开(公告)号:US11024387B2

    公开(公告)日:2021-06-01

    申请号:US17102712

    申请日:2020-11-24

    摘要: Techniques are provided for optimizing a program operation in a memory device to compensate for program speed variations due to block oxide thinning. In one approach, during a program operation, a program voltage which indicates program speed is acquired from sub-blocks with the highest and lowest program speeds. An initial program voltage for intermediate sub-blocks can be determined based on the acquired program voltages and the positions of the intermediate sub-blocks. The technique can accommodate a loss of one or both acquired program voltages if the programming is interrupted. In another approach, a program voltage which indicates program speed is acquired from one sub-block, and for a later-programmed sub-block, an appropriate offset is located from a table and summed with the acquired program voltage to determine an optimum initial program voltage.

    MEMORY DEVICE WITH COMPENSATION FOR ERASE SPEED VARIATIONS DUE TO BLOCKING OXIDE LAYER THINNING

    公开(公告)号:US20200335168A1

    公开(公告)日:2020-10-22

    申请号:US16922037

    申请日:2020-07-07

    摘要: Techniques are provided for optimizing an erase operation in a memory device to compensate for erase speed variations due to blocking oxide thinning In an erase operation for a block, the channels of NAND strings in different sub-blocks can be charged up by different amounts. One approach adjusts the control gate voltage of a first select gate transistor in a NAND string. This adjusts the amount of holes generated in the channel due to gate-induced drain leakage. Another approach adjusts the control gate voltage of additional select gate transistors in the NAND string to adjust the conductivity of the adjacent channel regions. Another approach applies different bit line voltages to different rows of NAND strings in each sub-block.

    MEMORY DEVICE WITH COMPENSATION FOR PROGRAM SPEED VARIATIONS DUE TO BLOCK OXIDE THINNING

    公开(公告)号:US20200243141A1

    公开(公告)日:2020-07-30

    申请号:US16847377

    申请日:2020-04-13

    摘要: Techniques are provided for optimizing a program operation in a memory device to compensate for program speed variations due to block oxide thinning. In one approach, during a program operation, a program voltage which indicates program speed is acquired from sub-blocks with the highest and lowest program speeds. An initial program voltage for intermediate sub-blocks can be determined based on the acquired program voltages and the positions of the intermediate sub-blocks. The technique can accommodate a loss of one or both acquired program voltages if the programming is interrupted. In another approach, a program voltage which indicates program speed is acquired from one sub-block, and for a later-programmed sub-block, an appropriate offset is located from a table and summed with the acquired program voltage to determine an optimum initial program voltage.

    Read bias adjustment for compensating threshold voltage shift due to lateral charge movement

    公开(公告)号:US10541035B1

    公开(公告)日:2020-01-21

    申请号:US16022373

    申请日:2018-06-28

    摘要: Apparatuses and techniques are provided for accurately reading memory cells by compensating for lateral charge diffusion between adjacent memory cells. A selected memory cell is read with a compensation which is based on classifying the threshold voltages of adjacent memory cells into bins. In one aspect, the compensation is based on the level of the current control gate voltage of the selected word line. In another aspect, the classifying of the threshold voltages of the adjacent memory cells can be a function of temperature. In another aspect, a memory cell can be read with compensation after a previous read operation without compensation results in an uncorrectable error. In another aspect, the classifying uses more bins for a selected edge word line.

    PREVENTING REFRESH OF VOLTAGES OF DUMMY MEMORY CELLS TO REDUCE THRESHOLD VOLTAGE DOWNSHIFT FOR SELECT GATE TRANSISTORS

    公开(公告)号:US20190259462A1

    公开(公告)日:2019-08-22

    申请号:US15900093

    申请日:2018-02-20

    摘要: Apparatuses and techniques are described for reducing charge loss in a select gate transistor in a memory device. In one aspect, a refresh operation is performed repeatedly to couple up data word line voltages but not dummy word line voltages. The refresh operation can involve applying a voltage pulse to the data word lines of a block when the block is not being used for a storage operation such as a program, read or erase operation. When the voltage pulse is applied to the data word lines, the dummy word lines can be set to a low level such as 0 V. This low level prevents or limits coupling up of the dummy memory cells to avoid creating an electric field which can cause holes to move from the dummy memory cells to adjacent select gate transistors.

    Reducing Hot Electron Injection Type Of Read Disturb In 3D Memory Device During Signal Switching Transients

    公开(公告)号:US20190074062A1

    公开(公告)日:2019-03-07

    申请号:US15694008

    申请日:2017-09-01

    IPC分类号: G11C16/08 G11C16/04

    摘要: A memory device and associated techniques for reducing read disturb of memory cells during a sensing process. Select gate transistors are transitioned to a conductive state one or more time during a sensing process, at the drain and/or source ends of the memory strings in an unselected sub-block. The transitioning can occur periodically, multiple times during the sensing process. When the select gate transistors are in a conductive state, accumulated holes in the channel can be removed. This help provide a faster decrease of the channel potential when the unselected word line voltages are ramped down at the end of the sensing process. The duration of a disturb-inducing channel gradient which is created next to the edge data memory cell is reduced so that read disturb of this cell is also reduced.

    Electric field to reduce select gate threshold voltage shift

    公开(公告)号:US10115464B1

    公开(公告)日:2018-10-30

    申请号:US15699490

    申请日:2017-09-08

    摘要: Non-volatile storage systems and method of operating non-volatile storage systems are disclosed. A crept up voltage on a dummy memory cell control gate adjacent to a select gate is prevented, reduced, and/or discharged. In some aspects, the crept up voltage is not allowed to happen on the dummy memory cell next to the select gate after a sensing operation. In some aspects, the voltage may creep up on the dummy memory cell control gate after a sensing operation, but it is discharged. Reducing and/or preventing the crept up voltage may reduce the electric field between the dummy memory cell and select gate transistor. This may prevent, or at least reduce, changes in threshold voltage of the select gate transistor. Additional problems may also be solved by a reduction of the crept up voltage on the dummy memory cell control gates.

    MODIFIED VERIFY SCHEME FOR PROGRAMMING A MEMORY APPARATUS

    公开(公告)号:US20210202022A1

    公开(公告)日:2021-07-01

    申请号:US16728716

    申请日:2019-12-27

    摘要: A memory apparatus and method of operation is provided. The apparatus includes memory cells coupled to a control circuit. The control circuit is configured to perform a first programming stage including iteratively programming each of the memory cells to first program states and verifying that the memory cells have a threshold voltage above one of a plurality of first verify voltages corresponding to the first program states. The first programming stage ends before all of the memory cells are verified thereby leaving a fraction of the memory cells below the one of the plurality of first verify voltages. The control circuit also performs a second programming stage including iteratively programming each of the memory cells to second program states and verifying that at least a predetermined number of the memory cells have the threshold voltage above one of a plurality of second verify voltages corresponding to the second program states.