A memory controller includes an interface and a processor. The interface communicates with memory cells organized in multiple Word Lines (WLs). The processor is configured to read a Code Word (CW) of an Error Correction Code (ECC) from a group of multiple memory cells belonging to a target WL, to calculate for a given memory cell (i) a first soft metric, depending on a first threshold voltage of a first neighbor memory cell in a first WL neighboring the target WL, and (ii) a second soft metric, depending on a second threshold voltage of a second neighbor memory cell in a second WL neighboring the target WL, to calculate a combined soft metric based on both the first and second soft metrics and assign the combined soft metric to the given memory cell, and to decode the CW based on the combined soft metric, to produce a decoded CW.

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.

Apparatus and methods are described to reduce program disturb for a memory string with a partial select gate drain, which is partially cut by a shallow trench. The memory string with a partial select gate drain is linked with a neighboring full select gate drain that during its programming can cause a program disturb in the memory string with a partial select gate drain. The bias voltage applied to the selected full select gate drain can be controlled from a high state for low memory program states to a lower state for the high memory program states. The high data states may cause program disturb. The reduction in the bias voltage can match a reduction in the bias voltage applied to the bit lines to reduce the program disturb while providing adequate signal to program the high states on the memory string of the full select gate drain.

Embodiments of erasing methods for a three-dimensional (3D) memory device are disclosed. The 3D memory device includes multiple decks vertically stacked over a substrate, wherein each deck includes a plurality of memory cells. The erasing method includes checking states of the plurality of memory cells of an erase-inhibit deck and preparing the erase-inhibit deck according to the states of the plurality of memory cells. The erasing method also includes applying an erase voltage at an array common source, applying a hold-release voltage on unselected word lines of the erase-inhibit deck, and applying a low voltage on selected word lines of a target deck.

A current operating characteristic value of a unit of the memory device is identified. An operating characteristic threshold value is identified from a set of operating characteristic thresholds, where the current operating characteristic value satisfies an operating characteristic threshold criterion that is based on the operating characteristic threshold value. A set of write-to-read (W2R) delay time thresholds that corresponds to the operating characteristic threshold value is identified from a plurality of sets of W2R delay time thresholds. Each of the W2R delay time thresholds in the set is associated with a corresponding read voltage level. A W2R delay time threshold associated with a W2R delay time threshold criterion is identified from the set of W2R delay time thresholds, where the W2R threshold criterion is satisfied by a current W2R delay time of the memory sub-system. A read voltage level associated with the identified W2R delay time threshold is identified.

A method for operating a three-dimensional (3D) memory device includes performing a first read operation for sensing a first memory cell of a first transistor string, and performing a subsequent second read operation for sensing a second memory cell of a second transistor string. Performing the first read operation includes applying a first bit line voltage to a first bit line, and maintaining the first bit line basically undischarged after data state of the first memory cell is detected.

A memory includes a first deck including a first set of word lines, a second deck above the first deck and including a second set of word lines, and a controller. The controller is configured to apply a program voltage to a first target word line of the first set of word lines in the first deck, and apply a first pass voltage to at least one of the first set of word lines that is below the first target word line when applying the program voltage to the first target word line. The controller is also configured to apply the program voltage to a second target word line of the second set of word lines in the second deck, and apply a second pass voltage to at least one of the second set of word lines that is below the second target word line when applying the program voltage to the second target word line. The second pass voltage is greater than the first pass voltage.

Methods, systems, and devices for write operation techniques for memory systems are described. In some memory systems, write operations performed on target memory cells of the memory device may disturb logic states stored by one or more adjacent memory cells. Such disturbances may cause reductions in read margins when accessing one or more memory cells, or may cause a loss of data in one or more memory cells. The described techniques may reduce aspects of logic state degradation by supporting operational modes where a host device, a memory device, or both, refrains from writing information to a region of a memory array, or inhibits write commands associated with write operations on a region of a memory array.

Systems and methods are disclosed, comprising a memory device comprising multiple groups of memory cells, the groups comprising a first group of memory cells and a second group of memory cells configured to store information at a same bit capacity per memory cell, and a processing device operably coupled to the memory device, the processing device configured to adjust a scan event threshold for one of the first or second groups of memory cells to a threshold less than a target scan event threshold for the first and second groups of memory cells to distribute scan events in time on the memory device.

Apparatus might include an array of memory cells and a controller to perform access operations on the array of memory cells. The controller might be configured to establish a negative potential in a body of a memory cell of the array of memory cells, and initiate a sensing operation on the memory cell while the body of the memory cell has the negative potential. Apparatus might further include an array of memory cells, a timer, and a controller to perform access operations on the array of memory cells. The controller might be configured to advance the timer, and establish a negative potential in a body of a memory cell of the array of memory cells in response to a value of the timer having a desired value.