Nonvolatile memory device

1. A nonvolatile memory device comprising:

a plurality of global word lines;

a plurality of first local word lines corresponding to a plurality of memory cells included in a first cell block;

a plurality of second local word lines corresponding to a plurality of memory cells included in a second cell block;

a plurality of first transistors configured to be turned on to transfer voltages of the global word lines to the first local word lines when the first cell block is selected among the first and second cell blocks;

a plurality of second transistors configured to be turned on to transfer the voltages of the global word lines to the second local word lines when the second cell block is selected among the first and second cell blocks; and

a voltage control unit configured to charge a bulk region of the plurality of transistors with a second negative voltage before a first negative voltage is applied to a global word line of the plurality of global word lines,

wherein the voltage control unit is configured to, when the first negative voltage is applied to the global word line of the plurality of global word lines, apply a third negative voltage to gates of the first or second transistors of the unselected one of the first and second cell blocks, respectively, and turn off the transistors applied with the third negative voltage.

2. The nonvolatile memory device of claim 1 , wherein the voltage control unit is configured to discharge the second negative voltage charged in the bulk region of the first and second transistors after the memory cells are completely programmed.

3. The nonvolatile memory device of claim 1 , wherein the first negative voltage applied to the global word line of the plurality of global word lines comprises a verification voltage for verifying whether a memory cell of a cell block selected between the first and second cell blocks is programmed or not.

4. The nonvolatile memory device of claim 1 , wherein the voltage control unit is configured to apply a turn-on voltage to a respective one of the first or second transistors in the selected one of the first and second cell blocks, respectively.

5. The nonvolatile memory device of claim 1 , wherein the third negative voltage is smaller than a value obtained by adding the first negative voltage and threshold voltages of the plurality of transistors and the second negative voltage is smaller than or equal to the first negative voltage.

6. The nonvolatile memory device of claim 5 , wherein the first to third negative voltages are equal to one another.

7. The nonvolatile memory device of claim 1 , wherein the voltage control unit includes:

a voltage generator configured to generate control voltages for controlling the cell blocks;

a controller configured to drive the plurality of global word lines with the voltages to be transferred to the first or second local word lines in response to an address signal; and

a back bias driver configured to apply a back bias voltage to the bulk region of the first and second transistors.

8. The nonvolatile memory device of claim 7 , the back bias driver is configured to apply the second negative voltage to the bulk region of the first and second transistors when a negative voltage operation signal is activated and apply a ground voltage to the bulk region of the first and second transistors when the negative voltage operation signal is deactivated.

9. The nonvolatile memory device of claim 7 , wherein the control voltages comprise a plurality of program voltages, a plurality of negative voltages, and a power supply voltage.