Semiconductor memory system performing read operation based on counted memory cells and operating method thereof

1. A semiconductor apparatus comprising:

a memory device including at least a word line; and

a controller suitable for controlling the memory device to perform a write operation and a read operation,

wherein the controller includes a counting unit suitable for counting a number of memory cells coupled to the word line for respective threshold voltages,

wherein the controller controls the memory device to perform a read operation based on the counted number of memory cells for the respective threshold voltages, and

wherein the controller further includes a mapping unit suitable for converting the counted number of memory cells for the respective threshold voltages into range values of accumulated number of cells and mapping the range value of accumulated number of cells to information bits.

2. The semiconductor apparatus of claim 1 , wherein the information bits have a value representing one among the range values of accumulated number of cells.

3. The semiconductor apparatus of claim 1 , wherein the mapping unit maps the counted number of memory cells for the respective threshold voltages to the information bits in a table having a plurality of range values of accumulated number of cells and the information bits.

4. The semiconductor apparatus of claim 3 , wherein the mapping unit generates the table by mapping the counted number of memory cells for the respective threshold voltages to the information bits through a binary search scheme.

5. The semiconductor apparatus of claim 3 ,

wherein the controller counts as a first value a number of memory cells coupled to the word line and turned on according to a first read voltage, and

wherein the controller further includes a read bias determination unit suitable for determining, when the read operation with the first read voltage fails, a second read voltage based on the first value and a range value of accumulated number of cells, which corresponds to the first read voltage among the plurality of range values of accumulated number of cells included in the table.

6. The semiconductor apparatus of claim 5 , wherein the read bias determination unit determines the second read voltage such that difference between the first value and a maximum value of the range value of accumulated number of cells, which corresponds to the first read voltage, or difference between the first value and a minimum value of the range of accumulated number of cells, which corresponds to the first read voltage, is under a predetermined threshold value.

7. The semiconductor apparatus of claim 5 ,

wherein the read bias determination unit decreases the second read voltage when the first value is greater than a maximum value of the range value of accumulated number of cells, which corresponds to the first read voltage, and

wherein the read bias determination unit increases the second read voltage when the first value is smaller than a minimum value of the range value of accumulated number of cells, which corresponds to the first read voltage.

8. The semiconductor apparatus of claim 5 , wherein the first read voltage is a default read voltage or a predetermined read voltage.

9. An operating method of a controller, the method comprising:

counting a number of memory cells coupled to a word line for respective threshold voltages; and

performing a read operation based on the counted number of memory cells for the respective threshold voltages, and

converting the counted number of memory cells for the respective threshold voltages into range values of accumulated number of cells and mapping the range value of accumulated number of cells to information bits.

10. The method of claim 9 , wherein the information bits have a value representing one among the range values of accumulated number of cells.

11. The method of claim 9 , wherein the converting of the counted number of memory cells includes mapping the counted number of memory cells for the respective threshold voltages to the information bits in a table having a plurality of range values of accumulated number of cells and the information bits.

12. The method of claim 11 , wherein the converting of the counted number of memory cells further includes generating the table by mapping the counted number of memory cells for the respective threshold voltages to the information bits through a binary search scheme.

13. The method of claim 11 ,

wherein the counting is performed by counting as a first value a number of memory cells coupled to the word line and turned on according to a first read voltage, and

further comprising determining, when the read operation with the first read voltage fails, a second read voltage based on the first value and a range value of accumulated number of cells, which corresponds to the first read voltage among the plurality of range values of accumulated number of cells included in the table.

14. The method of claim 13 , wherein the second read voltage is determined such that difference between the first value and a maximum value of the range value of accumulated number of cells, which corresponds to the first read voltage, or difference between the first value and a minimum value of the range of accumulated number of cells, which corresponds to the first read voltage, is under a predetermined threshold value.

15. The method of claim 13 , wherein the determining of the second read voltage includes:

decreasing the second read voltage when the first value is greater than a maximum value of the range value of accumulated number of cells, which corresponds to the first read voltage; and

increasing the second read voltage when the first value is smaller than a minimum value of the range value of accumulated number of cells, which corresponds to the first read voltage.

16. The method of claim 13 , wherein the first read voltage is a default read voltage or a predetermined read voltage.

17. An operating method of a controller the method comprising:

allocating range values to accumulated number of memory cells coupled to a word line for threshold voltages, respectively;

counting as a cell count an accumulated number of memory cells coupled to the word line and turned on according to a threshold voltage during a read operation;

adjusting, when the read operation fails, the threshold voltage of the read operation based on the cell count and one corresponding to the read-failed threshold voltage among the range values; and

repeating the counting and the adjusting until the cell count falls in the range value corresponding to the adjusted threshold voltage of the read operation.