Memory controller and method of operating the memory controller
A memory controller that controls a memory device including a memory block includes an initial program controller configured to control the memory device to program at least one or more monitoring memory cells from among memory cells respectively connected to monitoring word lines from among a plurality of word lines connected to the memory block, a pre-read controller configured to generate a shifting information of a threshold voltage distribution of the monitoring memory cells based on a result of reading the monitoring memory cells before a read operation is performed on the memory block, and a pre-program controller configured to control the memory device to perform the read operation after applying a pre-program voltage having a voltage level determined according to the shifting information to the plurality of word lines.
1. A memory controller that controls a memory device including a memory block, the memory controller comprising:
an initial program controller configured to control the memory device to program at least one or more monitoring memory cells from among memory cells respectively connected to monitoring word lines from among a plurality of word lines connected to the memory block;
a pre-read controller configured to generate a shifting information of a threshold voltage distribution of the monitoring memory cells based on a result of reading the monitoring memory cells before a read operation is performed on the memory block; and
a pre-program controller configured to control the memory device to perform the read operation after applying a pre-program voltage having a voltage level determined according to the shifting information to the plurality of word lines.
2. The memory controller of claim 1 , wherein the monitoring word lines are most adjacent to a select line connected to the memory block.
3. The memory controller of claim 1 , wherein the memory device further comprises:
a voltage generator configured to generate a voltage to be applied to the memory block; and
a row decoder configured to provide the voltage to the memory block.
4. The memory controller of claim 3 , wherein the monitoring memory cells are included in a string has closest physical distance from the row decoder among a plurality of strings included in the memory block.
5. The memory controller of claim 1 , wherein the monitoring memory cells is included in a string first exposed to high temperature environment among a plurality of strings included in the memory block.
6. The memory controller of claim 1 , wherein the initial program controller controls the memory device to program the monitoring memory cells using a single level cell method.
7. The memory controller of claim 1 , wherein the initial program controller controls the memory device to program data or dummy data to the monitoring memory cells.
8. The memory controller of claim 1 , wherein the pre-read controller controls the memory device to read the monitoring memory cells at a voltage level higher than a normal read voltage level that distinguishes between an erase state and a program state, before the read operation.
9. The memory controller of claim 1 , wherein the pre-read controller generates the shifting information indicating a shifting degree and outputs the shifting information to the preprogram controller, when the number of turned on memory cells is greater than or equal to a first reference value and less than a second reference value.
10. The memory controller of claim 9 , wherein the pre-program controller controls the memory device to apply program voltages to each of a plurality of groups by dividing the plurality of word lines into the plurality of groups according to a position connected to a string based on the shifting information.
11. The memory controller of claim 10 , wherein the program voltages increase from a group including a word line most adjacent to a source select line among the plurality of groups to a group including a word line most adjacent to a drain select line among the plurality of groups.
12. The memory controller of claim 9 , wherein the pre-read controller processes the read operation as a fail before the read operation is performed, when the number of the turned on memory cells is greater than or equal to the second reference value.
13. The memory controller of claim 9 , wherein the pre-read controller controls the memory device to read the monitoring memory cells at a read voltage level lower than a read voltage level used to obtain the result of reading the monitoring memory cells, when the number of the turned on memory cells is greater than or equal to the second reference value.
14. The memory controller of claim 13 , wherein when the number of the turned on memory cells is less than a third reference value, the pre-read controller generates shifting information indicating the shifting degree and outputs the shifting information to the pre-program controller, and
the pre-program controller controls the memory device to apply program voltages by dividing the plurality of word lines into a plurality of groups according to a position connected to a string based on the shifting information.
15. The memory controller of claim 14 , wherein the pre-read controller processes the read operation as a fail before the read operation is performed, when the number of the turned on memory cells is greater than or equal to the third reference value.
16. A method of operating a memory controller that controls a memory device including a memory block, the method comprising:
receiving a program request corresponding to the memory block from a host;
programming at least one or more monitoring memory cells among memory cells respectively connected to monitoring word lines from among a plurality of word lines connected to the memory block before a program operation corresponding to the program request is performed;
receiving a read request corresponding to the memory block from the host;
reading the monitoring memory cells before a read operation corresponding to the read request is performed;
generating a shifting information of a threshold voltage distribution of the monitoring memory cells based on a result of reading the monitoring memory cells; and
determining whether to program memory cells included in the memory block before the read operation based on the shifting information.
17. The method of claim 16 , wherein the monitoring word lines are most adjacent to a select line connected to the memory block.
18. The method of claim 16 , wherein in reading the monitoring memory cells, the monitoring memory cells are read at a voltage level higher than a normal read voltage level that distinguishes between an erase state and a program state.
19. The method of claim 16 , wherein in determining whether to program the memory cells included in the memory block, when the number of turned on memory cells is greater than or equal to a first reference value and less than a second reference value, it is determined to apply program voltages for each of a plurality of groups by dividing the plurality of word lines into the plurality of groups according to a position connected to a string.
20. The method of claim 19 , wherein in determining whether to program the memory cells included in the memory block, when the number of the turned on memory cells is greater than or equal to the second reference value, the read operation is processed as a fail before the read operation is performed.