A non-volatile memory device, described herein, comprises: a plurality of memory strings and at least one control circuit in communication with the non-volatile memory cell array. The at least one control circuit is configured to perform, for the plurality of memory strings, one erase-verify iteration in an erase operation including determining whether at least one memory string of the plurality of memory strings passes an erase-verify test. The at least one control circuit is configured to, if the at least one memory string passes the erase-verify test, inhibit the at least one memory string for erase including ramping up, to an erase voltage, of a voltage applied to a gate of a SGD transistor of the at least one memory string and to perform a next erase-verify iteration in the erase operation for remaining memory strings of the plurality of memory strings other than the at least one memory string.

A non-volatile memory device, described herein, comprises: a plurality of memory strings and at least one control circuit in communication with the non-volatile memory cell array. The at least one control circuit is configured to perform, for the plurality of memory strings, one erase-verify iteration in an erase operation including determining whether at least one memory string of the plurality of memory strings passes an erase-verify test. The at least one control circuit is configured to, if the at least one memory string passes the erase-verify test, inhibit the at least one memory string for erase including ramping up, to an erase voltage, of a voltage applied to a gate of a SGD transistor of the at least one memory string and to perform a next erase-verify iteration in the erase operation for remaining memory strings of the plurality of memory strings other than the at least one memory string.

A memory apparatus and method of operation are provided. The apparatus includes apparatus including memory cells connected to word lines including at least one dummy word line and data word lines. The memory cells are arranged in strings and are configured to retain a threshold voltage. The apparatus also includes a control means coupled to the word lines and the strings and configured to identify ones of the memory cells connected to the at least one dummy word line with the threshold voltage being below a predetermined detection voltage threshold following an erase operation. The control means is also configured to selectively apply at least one programming pulse of a maintenance program voltage to the at least one dummy word line to program the ones of the memory cells connected to the at least one dummy word line having the threshold voltage being below the predetermined detection voltage threshold.

In a method of operating one or more nonvolatile memory devices including one or more memory blocks, each memory block includes a plurality of memory cells and a plurality of pages arranged in a vertical direction. Pages arranged in a first direction of a channel hole are set as first to N-th pages. A size of the channel hole increases in the first direction and decreases in the second direction. Pages arranged in a second direction of the channel hole are set as (N+1)-th to 2N-th pages. First to N-th page pairs are set such that a K-th page among the first to the N-th pages and an (N+K)-th page among the (N+1)-th to 2N-th pages form one page pair. Parity regions of two pages included in at least one page pair are shared by the two pages included in the at least one page pair.

In a method of operating one or more nonvolatile memory devices including one or more memory blocks, each memory block includes a plurality of memory cells and a plurality of pages arranged in a vertical direction. Pages arranged in a first direction of a channel hole are set as first to N-th pages. A size of the channel hole increases in the first direction and decreases in the second direction. Pages arranged in a second direction of the channel hole are set as (N+1)-th to 2N-th pages. First to N-th page pairs are set such that a K-th page among the first to the N-th pages and an (N+K)-th page among the (N+1)-th to 2N-th pages form one page pair. Parity regions of two pages included in at least one page pair are shared by the two pages included in the at least one page pair.

Memory systems and devices with source plate discharge circuits (and associated methods) are described herein. In one embodiment, a memory device includes (a) a plurality of memory cells, (b) a source plate electrically coupled to the plurality of memory cells, and (c) a discharge circuit. The discharge circuit can include a bipolar junction transistor device electrically coupled to the source plate and configured to drop a voltage at the source plate by, for example, discharging current through the bipolar junction transistor device. In some embodiments, the bipolar junction transistor device can be activated using a low-voltage switch or a high-voltage switch electrically coupled to the bipolar junction transistor. In these and other embodiments, the bipolar junction transistor device can operate in an avalanche mode while discharging current to drop the voltage at the source plate.

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.

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.

A storage device includes 3D NAND including layers of multi-level cells. Test reads are performed by reading only LSB pages and reading layers in a repeating pattern of reading two and skipping two. A test read of a block is performed when its read count reaches a threshold. The counter threshold is updated according to errors detected during the test read such that the frequency of test reads increases with increase in errors detected. Counter thresholds according to errors may be specified in a table. The table may be selected as corresponding to a range of PEC values including the current PEC count of the 3D NAND. Each table further specifies a number of errors that will result in garbage collection being performed.