Nonvolatile memory device and method of programming the same
In a method of programming a three-dimensional nonvolatile memory device, a program loop is executed at least one time, wherein the program loop includes a programming step for programming selected memory cells among the memory cells and a verifying step for verifying whether the selected memory cells are program-passed or not. In the programming the selected memory cells, a level of a voltage being applied to a common source line connected to the strings in common may be changed. Thus, in a program operation, power consumption which is needed to charge-discharge the common source line can be decreased while increasing boosting efficiency.
1. A method of programming a nonvolatile memory device including a plurality of memory cells located at intersections of a plurality of cell strings that are perpendicular to a substrate and a plurality of word lines, the method comprising:
executing a plurality of program loops, wherein each of the program loops comprises:
programming selected memory cells among the plurality of memory cells; and
verifying whether the selected memory cells are program-passed or not, wherein:
each of the program loops is assigned to one of a plurality of periods in accordance with a ratio of memory cells being inhibited during the program loop to all the memory cells,
each of the periods is associated with a range of ratios differing from that of all other periods, and
a level of a common source line voltage (CSL voltage) being applied to a common source line during each of the loops varies for each of the periods.
2. The method of claim 1 , wherein the level of the voltage being applied to the common source line increases for each successive one of the periods.
3. The method of claim 2 , wherein in each of the periods, the level of the voltage being applied to the common source line is constant.
4. The method of claim 3 , wherein in a first period among the periods, the level of the voltage being applied to the common source line is 0V.
5. The method of claim 4 , wherein the programming further comprises:
applying a ground voltage to bit lines connected to strings connected to selected memory cells among the memory cells; and
applying a boosting voltage to bit lines connected to strings connected to unselected memory cells among the memory cells.
6. A method of operating a non-volatile memory device including a plurality of memory blocks, each memory block including memory cells stacked along a direction vertical to a substrate, a first cell string and a second cell string of the each memory block being connected to a bit line from among a plurality of bit lines, each of the first cell string and the second cell string including selection transistors and serially-connected memory cells, respectively, the first cell string and the second cell string being connected to a common source line (CSL) in common, the method comprising:
executing a plurality of program loops, wherein each program loop includes applying a common source line voltage (CSL voltage) to the CSL during applying a program voltage to a selected memory cell, wherein
a level of the CSL voltage varies according to a ratio of memory cells being inhibited, during applying the program voltage to the selected memory cell, to all memory cells of the first cell string and the second cell string.
7. The method of claim 6 , wherein the program loops are divided into a plurality of periods, each of the plurality of periods includes at least one program loop, and the level of the CSL voltage varies according to each of the plurality of periods.
8. The method of claim 7 , wherein the more each of the plurality of periods proceeds, the larger the level of the CSL voltage is.
9. The method of claim 8 , wherein in each of the plurality of periods, the level of the CSL voltage is constant.
10. The method of claim 8 , wherein in the first period among the plurality of periods, the level of the CSL voltage is 0V.
11. The method of claim 6 , wherein the programming step further comprises:
applying a ground voltage to a bit lines connected to a selected cell string; and
applying a boosting voltage to a bit line connected to an unselected cell string except the selected cell string.
12. The method of claim 6 , wherein the ratio is determined by a memory vendor in a production stage.
13. The method of claim 6 , further comprising compensating the level of the CSL voltage by sensing a peripheral temperature.
14. The method of claim 6 , wherein during applying the program voltage to the selected memory cell, the time for the CSL voltage to reach a target level after the CSL voltage is applied to the common source line varies.
15. A nonvolatile memory device comprising:
a memory cell array including a plurality of memory blocks, each memory block including memory cells stacked along a direction vertical to a substrate, a first cell string and a second cell string of the each memory block being connected to a bit line from among a plurality of bit lines, each of the first cell string and the second cell string including selection transistors and serially-connected memory cells, respectively, the first cell string and the second cell string being connected to a common source line (CSL) in common;
a row select circuit configured to derive a selected word line;
a page buffer connected to a bit line connected to a selected SSL;
a voltage generator configured to generate a program voltage and a common source line voltage (CSL voltage); and
a control logic configured to execute a plurality of program loops, wherein each program loop includes applying the CSL voltage to the CSL during applying the program voltage to a selected memory cell, wherein
a level of the CSL voltage varies according to a ratio of memory cells being inhibited, during applying the program voltage to the selected memory cell, to all memory cells of the first cell string and the second cell string.
16. The nonvolatile memory device of claim 15 , wherein the program loops are divided into a plurality of periods, each of the plurality of periods includes at least one program loop, and the level of the CSL voltage varies according to each of the plurality of periods.
17. The nonvolatile memory device of claim 15 , wherein the more each of the plurality of periods proceeds, the larger the level of the CSL voltage is.
18. The nonvolatile memory device of claim 17 , further comprising a common source line driver configured to transmit the CSL voltage to the CSL or configured to ground the CSL.
19. The nonvolatile memory device of claim 18 , wherein the common source line driver comprises:
a first transistor of which a drain electrode is connected to the voltage generator; and
a second transistor of which a drain electrode is connected to a source electrode of the first transistor and of which a source electrode is connected to a ground electrode, wherein
the source electrode of the first transistor is connected to the CSL.
20. The nonvolatile memory device of claim 18 , further comprising a temperature sensing circuit configured to generate a compensation signal that controls so that a voltage level of the CSL is compensated by sensing a peripheral temperature to transmit the compensation signal to the voltage generator.