Nonvolatile memory device and method of driving the same

A method of driving a nonvolatile memory device including a plurality of variable resistance memory cells, each of the plurality of variable resistance memory cells having a bit line coupled to the variable resistance memory cell and column selection transistor coupled between the variable resistance memory cell and the bit lines to receive a first control voltage being applied to a gate of the column selection transistor, the method comprising:

• during a first write verify operation, writing write data by providing a write bias to a selected memory cell from among the plurality variable resistance memory cells;
• and
• during a second write verify operation, writing the write data by providing the write bias to the selected variable resistance memory cell,
• wherein a level of the first control voltage in the first write verify operation is different from a level of the first control voltage in the second write verify operation.

A nonvolatile memory device comprising:

• a plurality of variable resistance memory cells;
• bit lines coupled to the plurality of variable resistance memory cells, respectively;
• column selection transistors coupled between the plurality of variable resistance memory cells and the bit lines, respectively, each of the column selection transistors being configured to receive a first control voltage being applied to a gate of the column selection transistor;
• and
• a write circuit coupled to the bit lines configured perform a write operation by providing a write bias to a selected memory cell from among the plurality of variable resistance memory cells to write data, the write circuit being configured to perform the write operation through one or more successive write verify operations,
• wherein a level of the first control voltage in a previous write verify operation is different from a level of the first control voltage in a subsequent write verify operation.