Disclosed is a semiconductor memory device and a method of operating the same. The semiconductor memory device includes a memory cell array including a plurality of memory blocks, a peripheral circuit configured to perform an erase characteristic check operation and an erase operation on the plurality of memory blocks. The semiconductor memory device also includes a control circuit configured to control the peripheral circuit to perform the erase characteristic check operation and the erase operation, determine whether each of the plurality of memory blocks has a normal erase characteristic or an overerase characteristic according to a result of the erase characteristic check operation for each of the plurality of memory blocks, and set an erase voltage of the erase operation based on the determined erase characteristic according to the result of the erase characteristic check operation.

According to one embodiment, a semiconductor memory device includes: a first memory cell; a second memory cell; a first word line; a second word line; and a first bit line. The device is configured to execute a first operation, a second operation, and a third operation to write data into the first memory cell. In the first operation, a first voltage is applied to the second word line. In the second operation, after the first operation, a second voltage higher than the first voltage is applied to the second word line. In the third operation, after the second operation, a third voltage higher than the second voltage is applied to the first word line, and a fourth voltage lower than both the second voltage and the third voltage is applied to the second word line.

According to one embodiment, a semiconductor memory device includes: a first memory cell; a second memory cell; a first word line; a second word line; and a first bit line. The device is configured to execute a first operation, a second operation, and a third operation to write data into the first memory cell. In the first operation, a first voltage is applied to the second word line. In the second operation, after the first operation, a second voltage higher than the first voltage is applied to the second word line. In the third operation, after the second operation, a third voltage higher than the second voltage is applied to the first word line, and a fourth voltage lower than both the second voltage and the third voltage is applied to the second word line.

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.

In a memory controller configured to control a memory device including a plurality of memory blocks, the memory controller comprising: a memory interface configured to exchange data with the memory device; and a pre-program controller configured to perform a read operation on a last page of a program sequence for a plurality of pages in an erase target memory block when the memory device is in an idle state, and perform a pre-program operation on the erase target memory block according to the result obtained by performing the read operation, wherein the erase target memory block is a memory block on which an erase operation is to be performed among the plurality of memory blocks, and wherein the erase operation on the erase target memory block is performed after the pre-program operation is performed.

A variety of applications can include memory systems that have one or more memory devices capable of performing memory operations on multiple blocks of memory in response to a command from a host. For example, improvement in erase performance can be attained by erasing multiple blocks of memory by one of a number of approaches. Such approaches can include parallel erasure followed by serial verification in response to a single command. Other approaches can include sequential erase and verify operations of the multiple blocks in response to a single command. Additional apparatus, systems, and methods are disclosed.

A memory controller includes an over-program controller that preprograms and then erases the memory cells such that each of the memory cells has a first threshold voltage level, wherein fast cells are detected among the memory cells according to a threshold voltage less than or equal to a second threshold voltage less than the first threshold voltage, and a processor that generates fast cell information identifying the fast cells among the memory cells and stores the fast cell information in a buffer. The over-program controller controls the over-programming of the fast cells and normal programming of normal cells among the memory cells based on the fast cell information stored in the buffer.

Each memory block in the flash memory is added with corresponding information bit(s) that store(s) information indicating whether erasure of the memory block has been completed before power-off. This allows easily finding out which memory block in the flash memory is undergoing an erase operation at the time of power-off. When the flash memory is powered on again, the information in the corresponding information bit(s) of the memory blocks may be read out and checked to determine whether there is any memory block of which the erasure had not been completed before the last power-off. If so, the memory blocks in the flash memory will be reprogrammed during the re-powering. This can avoid possible failure in reading data from some memory cells in the flash memory.

A controller of a memory device may determine that an endurance parameter associated with a wear leveling pool of a memory of the memory device satisfies a threshold. The wear leveling pool includes a plurality of memory blocks of the memory. The controller may divide, based on determining that the endurance parameter satisfies the threshold, the plurality of memory blocks of the wear leveling pool into a first wear leveling pool subset that includes a first subset of the plurality of memory blocks and a second wear leveling pool subset that includes a second subset of the plurality of memory blocks. A first subset of a plurality of data partitions is stored in the first subset of the plurality of memory blocks, and a second subset of the plurality of data partitions is stored in the second subset of the plurality of memory blocks.

This invention introduces a flash memory device and a method which are capable of quickly recovering the over-erased memory cells while preventing adverse influence to normal cells that are not over-erased. The flash memory device comprises a memory array and a memory controller coupled to the memory array. The memory controller is configured to select a memory block which comprises at least one over-erased memory cell. The memory controller is further configured to apply a negative voltage to the common bulk line and the common source line of the selected memory block. The memory controller is further configured apply a positive voltage to word lines that are coupled to the at least one over-erased memory cell in the selected memory block, and apply the positive voltage to word lines that are not coupled to any one of the at least one over-erased memory cell in the selected memory block.