Sensing in non-volatile memory is performed using bias conditions that are dependent on the position of a selected memory cell within a group of non-volatile memory cells. During sensing, a selected memory cell receives a reference voltage while the remaining memory cells receive a read or verify pass voltage. For at least a subset of the unselected memory cells, the pass voltage that is applied is dependent upon the position of the selected memory cell in the group. As programming progresses from a memory cell at a first end of a NAND string toward a memory cell at a second end of the NAND string, for example, the pass voltage for at least a subset of the unselected memory cells that have already been subjected to programming may be increased. This technique may reduce the effects of an increased channel resistance that occurs as more memory cells are programmed.

According to one embodiment, a memory system includes a non-volatile memory and a memory controller. The non-volatile memory includes a plurality of groups, each including a plurality of memory cells. The memory controller is configured to determine whether to execute a refresh process for a first group based on whether a first temperature in a write process for the first group and a second temperature after the write process for the first group satisfy a first condition.

Some embodiments include apparatuses and methods using first and second select gates coupled in series between a conductive line and a first memory cell string of a memory device, and third and fourth select gates coupled in series between the conductive line and a second memory cell string of the memory device. The memory device can include first, second, third, and fourth select lines to provide first, second, third, and fourth voltages, respectively, to the first, second, third, and fourth select gates, respectively, during an operation of the memory device. The first and second voltages can have a same value. The third and fourth voltages can have different values.

Methods, systems, and devices for data-based polarity write operations are described. A write command may cause a set of data to be written to a set of memory cells. To write the set of data, a write operation that applies voltages across the memory cells based on a logic state of data to be written to the memory cells may be used. During a first interval of the write operation, a voltage may be applied across a memory cell based on a logic state of a data bit to be written to the memory cell. During a second interval of the write operation, a voltage may be applied across the memory cell based on an amount of charge conducted by the memory cell during the first interval.

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.

Provided herein is a semiconductor memory device. The semiconductor memory device includes: a memory cell array including a plurality of memory blocks; a voltage generation circuit configured to generate a plurality of operating voltages; a decoder circuit configured to transmit the plurality of operating voltages to the memory cell array in response to a serial data signal that is sequentially inputted; and a control logic configured to generate the data signal, internal address signals and an internal clock signal in response to a command.

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.

A determination that a first programming operation has been performed on a particular memory cell can be made. A determination can be made, based on one or more threshold criteria, whether the particular memory cell has transitioned from a state associated with a decreased error rate to another state associated with an increased error rate. In response to determining that the particular memory cell has transitioned from the state associated with the decreased error rate to the another state associated with the increased error rate, an operation can be performed on the particular memory cell to transition the particular memory cell from the another state associated with the increased error rate to the state associated with the decreased error rate.

A determination that a first programming operation has been performed on a particular memory cell can be made. A determination can be made, based on one or more threshold criteria, whether the particular memory cell has transitioned from a state associated with a decreased error rate to another state associated with an increased error rate. In response to determining that the particular memory cell has transitioned from the state associated with the decreased error rate to the another state associated with the increased error rate, an operation can be performed on the particular memory cell to transition the particular memory cell from the another state associated with the increased error rate to the state associated with the decreased error rate.

A 3D memory device may include a first set of memory layers, a second set of memory layers above the first set of memory layers, and a first dummy memory layer between the first and second memory layers. The 3D memory device may include a plurality of NAND memory strings each extending through the first and second set of memory layers and the first dummy memory layer. The 3D memory device may include a word line (WL) driving circuit that, when programming one of the first set of memory layers, may be configured to apply a second pre-charge voltage to the first dummy memory layer during the pre-charge period. The second pre-charge voltage may overlap with the first pre-charge voltage and ramp down prior to the first pre-charge voltage.