Memory device and operating method of the memory device

1. A method for operating a memory device for performing a program operation of programming data in selected memory cells among a plurality of memory cells, the method comprising:

applying a program voltage to the selected memory cells;

verifying program states of memory cells programmed to any one program state among a plurality of program states distinguished based on a plurality of threshold voltages among the selected memory cells;

applying a predetermined lowest program voltage to the selected memory cells after a verify operation on the plurality of program states passes; and

verifying an erase state of memory cells programmed to an erase state among the selected memory cells after the lowest program voltage is applied to the selected memory cells.

2. The method of claim 1 , wherein the verifying of the erase state comprises verifying the erase state of the memory cells programmed to the erase state, after the verify operation on the plurality of program states passes.

3. The method of claim 1 , wherein the verifying of the program states comprises verifying the program states of the memory cells programmed to the one program state by applying a first verify voltage to a selected word line connected to the selected memory cells, and

wherein the verifying of the erase state comprises verifying the erase state of the memory cells programmed to the erase state by applying a second verify voltage lower than the first verify voltage to the selected word line.

4. The method of claim 3 , wherein the second verify voltage includes a negative verify voltage.

5. The method of claim 3 , wherein the verifying of the erase state comprises determining that the verify operation on the erase state has failed, when a threshold voltage of the memory cells programmed to the erase state is higher than the second verify voltage.

6. The method of claim 5 , further comprising programming the data in other memory cells except the selected memory cells among the plurality of memory cells, when the verify operation on the erase state has failed for the selected memory cells among the plurality of memory cells.

7. A method for operating a memory device for performing a program operation of programming data in selected memory cells among a plurality of memory cells, the method comprising:

performing a plurality of program loops including a program voltage apply operation of applying a program voltage to the selected memory cells and a verify operation of verifying at least one of program states and an erase state of the selected memory cells;

verifying program states of memory cells programmed to a specific program state among the selected memory cells in a verify operation included in at least one program loop corresponding to the specific program state among the plurality of program loops;

applying a predetermined lowest program voltage to the selected memory cells after a verify operation on the specific program state passes; and

verifying, after the lowest program voltage is applied to the selected memory cells, an erase state of memory cells programmed to an erase state among the selected memory cells in the verify operation included in the at least one program loop corresponding to the specific program state.

8. The method of claim 7 , wherein the specific program state includes a program state having a higher threshold voltage than other program states among a plurality of program states.

9. The method of claim 7 , wherein the verifying of the program state comprises verifying the program states of the memory cells programmed to the specific program state by applying a first verify voltage to a selected word line connected to the selected memory cells, and

wherein the verifying of the erase state comprises verifying the erase state of the memory cells programmed to the erase state by applying a second verify voltage lower than the first verify voltage to the selected word line.

10. The method of claim 9 , wherein the second verify voltage includes a negative verify voltage.

11. The method of claim 9 , wherein the verifying of the erase state comprises determining that a verify operation on the erase state has failed, when a threshold voltage of the memory cells programmed to the erase state is higher than the second verify voltage.

12. The method of claim 11 , further comprising programming the data in other memory cells except the selected memory cells among the plurality of memory cells, when the verify operation on the erase state has failed for the selected memory cells among the plurality of memory cells.

13. A memory device comprising:

a plurality of memory cells;

a peripheral circuit configured to perform a plurality of program loops including a program voltage apply operation of applying a program voltage to selected memory cells among the plurality of memory cells and a verify operation of verifying program states of the selected memory cells; and

a program operation controller configured to control the peripheral circuit to program data in the selected memory cells according to the plurality of program loops,

wherein the program operation controller controls the peripheral circuit to verify program states of memory cells programmed to any one program state among a plurality of program states distinguished based on a plurality of threshold voltages among the selected memory cells in the verify operation, apply a predetermined lowest program voltage to the selected memory cells after the verify operation on the plurality of program states passes, and verify an erase state of memory cells programmed to an erase state among the selected memory cells.

14. The memory device of claim 13 , wherein the program operation controller controls the peripheral circuit to verify the erase state of the memory cells programmed to the erase state, after a verify operation on the plurality of program states passes.

15. The memory device of claim 13 , wherein the program operation controller controls the peripheral circuit to verify the program states of the memory cells programmed to the specific program state among the selected memory cells and the erase state of the memory cells programmed to the erase state among the selected memory cells in a verify operation of at least one program loop corresponding to the specific program state among the plurality of program loops, and

wherein the specific program state includes a program state having a higher threshold voltage than other program states among the plurality of program states.

16. The memory device of claim 13 , wherein the program operation controller controls the peripheral circuit to apply a first verify voltage for verifying the program state of the memory cells programmed to the one program state to a selected word line connected to the selected memory cells, and apply a second verify voltage for verifying the erase state of the memory cells programmed to the erase state to the selected word line, and

wherein the second verify voltage is lower than the first verify voltage.

17. The memory device of claim 16 , wherein the second verify voltage includes a negative verify voltage.

18. The memory device of claim 16 , wherein the program operation controller determines that a verify operation on the erase state has failed, when a threshold voltage of the memory cells programmed to the erase state is higher than the second verify voltage.

19. The memory device of claim 18 , wherein, when the verify operation on the erase state has failed for the selected memory cells among the plurality of memory cells, the program operation controller controls the peripheral circuit to program the data in other memory cells except the selected memory cells among the plurality of memory cells.