In a memory device having improved reliability, the memory device includes: a memory device comprising: a memory cell array including memory cells; a program operation controller configured to perform a program operation on the memory cells to any one state among first to nth states; a voltage generator configured to generate operating voltages respectively corresponding to the first to nth states in the program operation; a verify operation controller configured to verify whether the program operation performed on selected memory cells to a kth state, has been completed, and count a number of over-programmed memory cells having a threshold voltage greater than a threshold voltage corresponding to the kth state among the selected memory cells; and an over-program manager configured to increase operating voltages corresponding to (k+1)th to nth states to be greater than default values according to the number of over-programmed memory cells.

A memory system includes a nonvolatile memory device including a plurality of memory cells; and a controller including a control unit and a random-access memory, and configured to determine, by applying a program verify voltage to at least one memory cell to be programmed with program data, whether the program data is programmed, wherein the control unit determines percentages of a count of read requests received from a host device and a count of program requests received from the host device, and adjusts a level of the program verify voltage based on the percentages.

A nonvolatile semiconductor memory device includes a control circuit configured to control a soft program operation of setting nonvolatile memory cells to a first threshold voltage distribution state of the nonvolatile memory cells. When a characteristic of the nonvolatile memory cells is in a first state, the control circuit executes the soft program operation by applying a first voltage for setting the nonvolatile memory cells to the first threshold voltage distribution state to first word lines, and applying a second voltage higher than the first voltage to a second word line. When the characteristic of the nonvolatile memory cells is in a second state, the control circuit executes the soft program operation by applying a third voltage equal to or lower than the first voltage to the first word lines and applying a fourth voltage lower than the second voltage to the second word line.

According to one embodiment, a memory system includes a non-volatile semiconductor memory that includes a memory cell and a controller having a memory storing a write parameter used in a write operation to the memory cell. The controller instructs the non-volatile semiconductor memory to perform the write operation to the memory cell using the write parameter, receives, from the non-volatile semiconductor memory, a result of checking of the write parameter which is obtained in the write operation and updates the write parameter stored in the memory on the basis of the result of checking of the write parameter.

A nonvolatile semiconductor memory device includes a control circuit configured to control a soft program operation of setting nonvolatile memory cells to a first threshold voltage distribution state of the nonvolatile memory cells. When a characteristic of the nonvolatile memory cells is in a first state, the control circuit executes the soft program operation by applying a first voltage for setting the nonvolatile memory cells to the first threshold voltage distribution state to first word lines, and applying a second voltage higher than the first voltage to a second word line. When the characteristic of the nonvolatile memory cells is in a second state, the control circuit executes the soft program operation by applying a third voltage equal to or lower than the first voltage to the first word lines and applying a fourth voltage lower than the second voltage to the second word line.

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.

A memory device may include: a control circuit comprising a first verification component suitable for counting the number of memory cells in the selected word line having an excessively high threshold voltage as excessive memory cells, after a program operation is completed; and a second verification component suitable for counting the number of failed bits when the number of excessive memory cells counted is greater than or equal to an excess threshold value, and suitable for outputting a pass or fail signal for the program operation according to the count of at least one of the first verification component and the second verification component.

A non-volatile memory device may include a memory cell array, a peripheral circuit and a control logic. The memory cell array may include pages including data cells and over-program flag cells configured to represent whether or not the data cells may correspond to an over-programmed cells. The peripheral circuit may be configured to store data in the memory cell array or read the data from the memory cell array. The control logic may be configured to determine whether or not the data cells are programmable when a program command may be received from an external device. The control logic may be configured to program the over-program flag cell corresponding to the data cells when the data cells are not programmable.

Methods of operating a memory device include programming a page of a memory block of the memory device using a particular starting programming voltage, determining a programming voltage indicative of a programming efficiency of the page of the memory block during programming of the page of the memory block, storing a representation of the programming voltage indicative of the programming efficiency of the page of the memory block, setting a starting programming voltage for a different page of the memory block in response to the stored representation of the programming voltage indicative of the programming efficiency of the page of the memory block, and programming the different page of the memory block using its starting programming voltage.

Apparatuses and techniques are described for optimizing a program operation in a memory device. A storage location stores programing data for each word line, such as a program voltage for a set of memory cells. The set of memory cells may be periodically evaluated to determine updated programming setting(s). In one approach, the evaluation involves repeatedly sensing the set of memory cells between a program pulse and a verify signal in a program loop. The word line voltage can be stepped down to an intermediate voltage, then ramped down at a controlled rate while repeatedly sensing the memory cells, such as to detect an upper or lower tail of a threshold voltage distribution. The position of the tail can indicate a degree of over programming and this information can be used to adjust the programming setting(s) in a subsequent program operation.