Resistive memory device and method of operating the resistive memory device
Provided herein may be a resistive memory device and a method of operating the resistive memory device. The resistive memory device may include strings coupled between one or more source lines and one or more bit lines, each string including a set of one or more resistive memory cells, one or more word lines respectively coupled to the set of one or more resistive memory cells; and a voltage generator configured to control a level of a turn-on voltage to be applied to one or more unselected word lines among the one or more word lines depending on a program target state of a subset of resistive memory cells including one or more resistive memory cells selected from among the set of one or more resistive memory cells.
1. A resistive memory device, comprising:
strings respectively coupled between source lines and bit lines, wherein the strings include source select transistors respectively coupled to the source lines, drain select transistors respectively coupled to the bit lines, and resistive memory cells between the drain select transistors and the source select transistors;
word lines coupled to the resistive memory cells;
a source select line coupled to the source select transistors;
a drain select line coupled to the drain select transistors;
page buffers configured to selectively apply a set voltage to bit lines coupled to selected resistive memory cells among the resistive memory cells; and
a voltage generator configured to control a level of a turn-on voltage applied to the source select line depending on a program target state of the selected resistive memory cells.
2. The resistive memory device according to claim 1 , wherein the voltage generator is configured to increase the level of the turn-on voltage when the program target state rises.
3. The resistive memory device according to claim 2 , wherein the turn-on voltage is set to a positive voltage greater than a ground voltage.
4. The resistive memory device according to claim 1 , wherein the page buffers generate a ground voltage to be applied to bit lines coupled to unselected resistive memory cells.
5. The resistive memory device according to claim 1 , wherein the set voltage is set to a positive voltage greater than a ground voltage.
6. The resistive memory device according to claim 1 , wherein the voltage generator is configured to generate a turn-off voltage to be applied to a selected word line coupled to the selected resistive memory cells.
7. The resistive memory device according to claim 6 , wherein the turn-off voltage is set to a ground voltage.
8. The resistive memory device according to claim 1 , wherein the voltage generator is configured to generate a voltage having a greatest level of the turn-on voltage to be applied to unselected word lines coupled to unselected resistive memory cells.
9. The resistive memory device according to claim 1 , wherein, the voltage generator is configured to generate a reset voltage to be applied to the source lines, respectively.
10. The resistive memory device according to claim 9 , wherein the reset voltage is set to a negative voltage lower than a ground voltage.
11. A method of operating a resistive memory device during a program operation performed on resistive memory cells coupled between source select transistors respectively coupled to source lines and drain select transistors respectively coupled to bit lines, the method comprising:
applying a ground voltage to the source lines and applying a set voltage greater than the ground voltage to bit lines selected from among the bit lines;
applying a turn-off voltage to a selected word line coupled to resistive memory cells selected from among the resistive memory cells;
applying a turn-on voltage, a level of which is controlled depending on a program target state of the selected resistive memory cells, to a source select line coupled to the source select transistors; and
applying a voltage having a greatest level of the turn-on voltage to unselected word lines coupled to unselected resistive memory cells among the resistive memory cells.
12. The method according to claim 11 , wherein the turn-off voltage is set to the ground voltage.
13. The method according to claim 11 , wherein the turn-on voltage is set to a positive voltage greater than the turn-off voltage.
14. The method according to claim 11 , wherein the level of the turn-on voltage applied to the source select line is controlled to be greater as the program target state rises.
15. The method according to claim 11 , wherein, when the program operation is performed on the selected resistive memory cells, the ground voltage is applied to bit lines unselected from among the bit lines.