Disclosed in some examples are systems, methods, memory devices, and machine readable mediums for a fast secure data destruction for NAND memory devices that renders data in a memory cell unreadable. Instead of going through all the erase phases, the memory device may remove sensitive data by performing only the pre-programming phase of the erase process. Thus, the NAND doesn't perform the second and third phases of the erase process. This is much faster and results in data that cannot be reconstructed. In some examples, because the erase pulse is not actually applied and because this is simply a programming operation, data may be rendered unreadable at a per-page level rather than a per-block level as in traditional erases.

Some embodiments include apparatus and methods using access lines, first memory cells coupled to an access line of the access lines, and a control unit including circuitry. The control unit is configured to apply a first voltage to the access line; check first threshold voltages of the first memory cells after applying the first voltage; obtain offset information based on a determination that at least one of the first threshold voltages is greater than a selected voltage; generate a second voltage, the second voltage being a function of the first voltage and the offset information; and apply the second voltage to one of the access lines during an operation of storing information in second memory cells.

Disclosed in some examples are systems, methods, memory devices, and machine readable mediums for a fast secure data destruction for NAND memory devices that renders data in a memory cell unreadable. Instead of going through all the erase phases, the memory device may remove sensitive data by performing only the pre-programming phase of the erase process. Thus, the NAND doesn't perform the second and third phases of the erase process. This is much faster and results in data that cannot be reconstructed. In some examples, because the erase pulse is not actually applied and because this is simply a programming operation, data may be rendered unreadable at a per-page level rather than a per-block level as in traditional erases.

A semiconductor memory device according to an embodiment includes a string, a bit line, a well line, and a sequencer. The string includes first and second select transistors, and memory cell transistors using a ferroelectric material. The bit line and the well line are connected to the first and second select transistors, respectively. At a time in an erase verify operation, the sequencer is configured to apply a first voltage to the memory cell transistors, to apply a second voltage lower than the first voltage to the first select transistor, to apply a third voltage lower than the first voltage to the second select transistor, to apply a fourth voltage to the bit line, and to apply a fifth voltage higher than the fourth voltage to the well line.

Storage devices are capable of utilizing failed bit count (FBC) reduction devices to reduce FBCs for word lines in blocks. An FBC reduction device may include a FBC count component, a threshold component, a pre-verify component, and a soft program component. The FBC count component may access the FBC for the word line, where the block has unprogrammed word lines in an unprogrammed region separated from programmed word lines of a programmed region by the word line. The threshold component may determine whether the FBC of the word line exceeds a predetermined threshold. When the FBC exceeds the threshold, the pre-verify component may perform pre-verify operations on the programmed region. The soft program component may program the word line with first data equal to second data programmed in a second block. In response to disabling pre-verify operations, the program component may program the unprogrammed word lines in the unprogrammed region.

Embodiments provide a scheme for estimating an optimal read threshold voltage using a deep neural network (DNN) with a reduced number of processing. A controller includes a combined neural network, which receives first and second cumulative distribution function (CDF) values, each CDF value corresponding to a program voltage (PV) level associated with a read operation on the cells. The combined neural network generates first and second connection vectors based on the first and second CDF values and first weight values, and estimates an optimal read threshold voltage based on the first and second connection vectors and second weight values.

A method of detecting, by a nonvolatile memory system, a defective memory cell block from among memory cell blocks, includes performing, after performing an erase operation, a read operation on at least some memory cells included in a target memory cell block based on an off-cell detection voltage that is different from a read reference voltage that distinguishes an off-cell on which no data is written from an on-cell on which data is written; counting a number of hard off-cells having a higher threshold voltage than the off-cell detection voltage from among the memory cells based on a result of performing the read operation; and identifying whether the target memory cell block is a defective memory cell block based on the number of counted hard off-cells.

A memory apparatus and a control method are provided. The memory apparatus includes a non-volatile memory array having plural memory groups, and the control method is applied to the non-volatile memory array. The memory groups jointly share a first well, and the control method is applied to the non-volatile memory array. A first memory group among the memory groups is erased according to a first erase command after the memory apparatus is power-on, and a first amount of the memory groups are recovered in a first erase-recover procedure after the first memory group is erased. A second memory group among the memory groups is erased according to a second erase command after the first erase-recover procedure, and a second amount of the memory groups are recovered in a second erase-recover procedure after the second memory group is erased. The first amount is greater than the second amount.

The present disclosure includes systems, apparatuses, and methods related to generating a random data value. For example, a first read operation may be performed on a memory cell programmed to a first state, wherein the first read operation is performed using a first read voltage that is within a predetermined threshold voltage distribution corresponding to the first state. A programming signal may be applied to the memory cell responsive to the first read operation resulting in a snapback event, wherein the programming signal is configured to place the memory cell in a second state. A second read operation may be performed to determine whether the memory cell is in the first state or the second state using a second read voltage that is between the predetermined threshold voltage distribution corresponding to the first state and a second threshold voltage distribution corresponding to the second state.

A storage device comprising: a nonvolatile memory device including a plurality of memory blocks; and a device controller configured to control the nonvolatile memory device to determine a memory block to perform a refresh operation and to control the memory block to perform the refresh operation to recover data of the memory block.