Memory device, memory system, and operation method of memory device
Examples of the present application disclose a memory device, a memory system, and an operation method of a memory device. In the method, prior to ISPP programming of memory cells of selected memory cells, a first preprogram pulse is first applied to a selected word line to preprogram a first class of memory cells of the selected memory cells.
1 . A memory device, comprising:
a memory array comprising a plurality of memory cells;
a plurality of word lines coupled to the plurality of memory cells; and
a peripheral circuit coupled to the plurality of word lines and configured to:
apply a first preprogram pulse to a selected word line to preprogram a first class of memory cells of selected memory cells, wherein a target programmed state of the first class of memory cells is a first target programmed state, wherein after application of the first preprogram pulse a threshold voltage of the first class of memory cells is less than a first target threshold voltage, wherein the first target threshold voltage is a threshold voltage corresponding to the first target programmed state, wherein a difference between a voltage of the first preprogram pulse and a first target program voltage is less than a first difference threshold, and wherein the first target program voltage is set based on a program voltage required by a programmed state of the first class of memory cells to reach the first target programmed state; and
apply program pulses to the selected word line using increment step pulse programming (ISPP) to program the selected memory cells.
2 . The memory device of claim 1 , wherein the peripheral circuit is further configured to:
apply a second preprogram pulse to the selected word line to preprogram a second class of memory cells of the selected memory cells,
wherein a target programmed state of the second class of memory cells is a second target programmed state, after application of the second preprogram pulse a threshold voltage of the second class of memory cells is less than a second target threshold voltage, and the second target threshold voltage is a threshold voltage corresponding to the second target programmed state.
3 . The memory device of claim 1 , wherein before the application of the first preprogram pulse, a distance between a state of the first class of memory cells and the first target programmed state is greater than a distance between a state of at least one other memory cell in a selected memory cell row and a respective target programmed state.
4 . The memory device of claim 1 , wherein the peripheral circuit is further configured to:
determine the first preprogram pulse based on a difference between a current threshold voltage of at least one memory cell in the first class of memory cells and the first target threshold voltage.
5 . The memory device of claim 4 , wherein the peripheral circuit is configured to:
in response to the difference between the current threshold voltage of the at least one memory cell in the first class of memory cells and the first target threshold voltage exceeding a second difference threshold, configure the first preprogram pulse for the first class of memory cells.
6 . The memory device of claim 1 , wherein the peripheral circuit is configured to:
in response to a programming instruction from a controller, apply the first preprogram pulse to the selected word line to preprogram the first class of memory cells of the selected memory cells.
7 . The memory device of claim 6 , wherein the memory cells in the memory device are triple-level cells (TLC).
8 . The memory device of claim 1 , wherein the peripheral circuit is configured to:
in response to a programming instruction from a controller, apply the program pulses to the selected word line using the ISPP to perform first-time programming on the memory cells of the selected memory cells;
apply the first preprogram pulse to the selected word line to preprogram the first class of memory cells of the selected memory cells; and
apply the program pulses to the selected word line using the ISPP to perform second-time programming on the memory cells of the selected memory cells,
wherein a number of programmed states in threshold voltage distributions of a selected memory cell row after the second-time programming is greater than the number of programmed states in threshold voltage distributions of the selected memory cell row after the first-time programming.
9 . The memory device of claim 8 , wherein the memory cells in the memory device are quad-level cells (QLC).
10 . A memory system, comprising:
a memory device; and
a controller coupled to the memory device and configured to control the memory device,
wherein the memory device is configured to:
apply a first preprogram pulse to a selected word line to preprogram a first class of memory cells of selected memory cells, wherein a target programmed state of the first class of memory cells is a first target programmed state, after application of the first preprogram pulse a threshold voltage of the first class of memory cells is less than a first target threshold voltage, and the first target threshold voltage is a threshold voltage corresponding to the first target programmed state, wherein a difference between a voltage of the first preprogram pulse and a first target program voltage is less than a first difference threshold, and wherein the first target program voltage is set based on a program voltage required by a programmed state of the first class of memory cells to reach the first target programmed state; and
apply program pulses to the selected word line using increment step pulse programming (ISPP) to program the selected memory cells.
11 . The memory system of claim 10 , wherein:
the controller is configured to: send a programming instruction to the memory device; and
the memory device is configured to: in response to the programming instruction from the controller, apply the first preprogram pulse to the selected word line to preprogram the first class of memory cells of the selected memory cells.
12 . The memory system of claim 10 , wherein:
the controller is configured to: send a programming instruction to the memory device; and
the memory device is further configured to:
in response to the programming instruction from the controller, apply the program pulses to the selected word line using the ISPP to perform first-time programming on the memory cells of the selected memory cells;
apply the first preprogram pulse to the selected word line to preprogram the first class of memory cells of the selected memory cells; and
apply the program pulses to the selected word line using the ISPP to perform second-time programming on the memory cells of the selected memory cells,
wherein a number of programmed states in threshold voltage distributions of a selected memory cell row after the second-time programming is greater than the number of programmed states in threshold voltage distributions of the selected memory cell row after the first-time programming.
13 . A method of operating a memory device, comprising:
applying a first preprogram pulse to a selected word line to preprogram a first class of memory cells of selected memory cells, wherein a target programmed state of the first class of memory cells is a first target programmed state, after application of the first preprogram pulse a threshold voltage of the first class of memory cells is less than a first target threshold voltage, and the first target threshold voltage is a threshold voltage corresponding to the first target programmed state, wherein a difference between a voltage of the first preprogram pulse and a first target program voltage is less than a first difference threshold, and wherein the first target program voltage is set based on a program voltage required by a programmed state of the first class of memory cells to reach the first target programmed state; and
applying program pulses to the selected word line using increment step pulse programming (ISPP) to program the selected memory cells.
14 . The method of claim 13 , before applying the program pulses to the selected word line using the increment step pulse programming (ISPP) further comprising:
applying a second preprogram pulse to the selected word line to preprogram a second class of memory cells of the selected memory cells,
wherein a target programmed state of the second class of memory cells is a second target programmed state, after application of the second preprogram pulse a threshold voltage of the second class of memory cells is less than a second target threshold voltage, and the second target threshold voltage is a threshold voltage corresponding to the second target programmed state.
15 . The method of claim 13 , wherein before the application of the first preprogram pulse, a distance between a state of the first class of memory cells and the first target programmed state is greater than a distance between a state of at least one other memory cell in a selected memory cell row and a respective target programmed state.
16 . The method of claim 13 , before the application of the first preprogram pulse to the selected word line, further comprising:
determining the first preprogram pulse based on a difference between a current threshold voltage of at least one memory cell in the first class of memory cells and the first target threshold voltage.
17 . The method of claim 16 , wherein the determining the first preprogram pulse based on the difference between the current threshold voltage of at least one memory cell in the first class of memory cells and the first target threshold voltage comprises:
in response to the difference between the current threshold voltage of the at least one memory cell in the first class of memory cells and the first target threshold voltage exceeding a second difference threshold, configuring the first preprogram pulse for the first class of memory cells.
18 . The method of claim 13 , wherein the application of the first preprogram pulse to the selected word line comprises:
in response to a programming instruction from a controller, applying the first preprogram pulse to the selected word line to preprogram the first class of memory cells of the selected memory cells.