A memory device includes an erase operation controller for performing an erase operation on a memory block; an erase suspend count manager for managing an erase suspend count representing a number of times the erase operation is suspended until the erase operation on the memory block is completed; and a program parameter value determiner for determining a parameter value to be used for a program operation on the memory block, based on the erase suspend count.

According to one embodiment, a memory system includes a first memory and a memory controller. The first memory is nonvolatile and includes a plurality of memory cell transistors, each of which stores data corresponding to a threshold voltage. The memory controller causes the first memory to execute a read operation to acquire data corresponding to the threshold voltage from the plurality of memory cell transistors on the basis of a result of comparison between the threshold voltage and a read voltage. The memory controller selects a first candidate value from among a plurality of candidate values for the read voltage in accordance with a degree of stress that affects the threshold voltage; and causes the first memory to execute the read operation using the first candidate value as the read voltage.

An electronic device, and an over-erase detection and elimination method for memory cells are provided; the method includes: performing an erase operation on a specified area; selecting all the memory cells in the selected area one by one; measuring a threshold voltage of a selected memory cell for over-erase detection to see if it is less than a normal erase threshold voltage; if not, selecting the next memory cell for over-erase detection, and if yes, then performing a soft-write operation on the selected memory cell; after the soft-write operation, performing over-erase detection again to see whether the threshold voltage of the selected memory cell is within a normal threshold range; and if not, performing a soft-write operation again, and if yes, the next memory cell is selected for over-erase detection, until the threshold voltages of all the memory cells selected for erasure are within the normal threshold range.

A memory system may include a memory cell array including a plurality of memory blocks; a peripheral circuit configured to apply a check voltage for acquiring check data to a target memory block and apply program voltages to the target memory block in a pre-program operation for the target memory block; and a controller configured to control the peripheral circuit, determine status information on the target memory block based on the check data, and variably apply a program start voltage to the target memory block based on the status information in the pre-program operation.

A memory device includes an erase operation controller for performing an erase operation on a memory block; an erase suspend count manager for managing an erase suspend count representing a number of times the erase operation is suspended until the erase operation on the memory block is completed; and a program parameter value determiner for determining a parameter value to be used for a program operation on the memory block, based on the erase suspend count.

An example method includes, performing a first erase verify on a first set of memory cells of a portion of an array of memory cells, performing a second erase verify on a second set of memory cells of the portion of the array, applying a first erase voltage pulse concurrently to each memory cell in the portion of the array if the first set fails the first erase verify and if the second set fails the second erase verify, and applying a second erase voltage pulse concurrently to each memory cell in the portion of the array if the first set passes the first erase verify and if the second set fails the second erase verify. The second erase voltage pulse is different than the first erase voltage pulse.

A memory device includes an erase operation controller for performing an erase operation on a memory block; an erase suspend count manager for managing an erase suspend count representing a number of times the erase operation is suspended until the erase operation on the memory block is completed; and a program parameter value determiner for determining a parameter value to be used for a program operation on the memory block, based on the erase suspend count.

A memory system may include a memory cell array including a plurality of memory blocks; a peripheral circuit configured to apply a check voltage for acquiring check data to a target memory block and apply program voltages to the target memory block in a pre-program operation for the target memory block; and a controller configured to control the peripheral circuit, determine status information on the target memory block based on the check data, and variably apply a program start voltage to the target memory block based on the status to information in the pre-program operation.

An example method includes, performing a first erase verify on a first set of memory cells of a portion of an array of memory cells, performing a second erase verify on a second set of memory cells of the portion of the array, applying a first erase voltage pulse concurrently to each memory cell in the portion of the array if the first set fails the first erase verify and if the second set fails the second erase verify, and applying a second erase voltage pulse concurrently to each memory cell in the portion of the array if the first set passes the first erase verify and if the second set fails the second erase verify. The second erase voltage pulse is different than the first erase voltage pulse.

An erasing method used in a flash memory having memory blocks is illustrated, each of the memory blocks is divided into a plurality of memory sectors, and steps of the erasing method is illustrated as follows. An erasing and verifying process is performed sequentially on the memory blocks or the memory sectors of the memory block according to a memory sector enable signal. An over-erased correcting and verifying process is performed sequentially on the memory blocks or the memory sectors of the memory block according to the memory sector enable signal, wherein the memory sector enable signal is set to be asserted if an over-erased correction is performed on at least one of the memory blocks or at least one of the memory sectors of the memory block.