Semiconductor memory device applying different voltages to respective select gate lines

1. A semiconductor memory device comprising:

a memory string including first and second select transistors and memory cell transistors which are serially connected in this order;

a bit line connected to the first select transistor;

word lines which are connected to gates of the memory cell transistors, respectively, and which are stacked via insulating layers;

first and second select gate lines which are connected to gates of the first and second select transistors, respectively, and which are stacked on the word lines via insulating layers;

a first contact plug connected to the first select gate line;

a first wiring layer provided on the first contact plug;

a second contact plug connected to the second select gate line;

a second wiring layer provided on the second contact plug; and

a row decoder connected to the first and second wiring layers,

wherein the row decoder is configured to be capable of applying different voltages to the first select gate line and the second select gate line,

at a first time, the row decoder applies a first voltage to the first and second select gate lines, and applies a second voltage to the word lines,

at a second time, the row decoder applies a ground voltage to the second select gate line and the word lines, and

at a third time, the row decoder applies the ground voltage to the first select gate line, and applies a third voltage to the word lines.

2. The device according to claim 1 , wherein

the row decoder drops a voltage of the first select gate line at a raising timing of voltages of the word lines.

3. The device according to claim 1 , wherein

at a fourth time, the row decoder applies a write voltage higher than the third voltage to a selected word line.

4. The device according to claim 1 , further comprising:

a third select transistor connected between the second select transistor and the memory cell transistors; and

a third select gate line which is connected to a gate of the third select transistor and which is provided between the word lines and the second select gate line via an insulating layer,

wherein the row decoder applies the same voltage as that of the second select gate line to the third select gate line.

5. The device according to claim 4 , wherein

at the first time, the row decoder applies the first voltage to the first to third select gate lines, and applies the second voltage to the word lines,

at the second time, the row decoder applies the ground voltage to the second and third select gate lines and the word lines, and

at the third time, the row decoder applies the ground voltage to the first select gate line, and applies the third voltage to the word lines.

6. The device according to claim 5 , wherein

at a fourth time, the row decoder applies a write voltage higher than the third voltage to a selected word line.

7. The device according to claim 4 , further comprising:

a third contact plug connected to the second select gate line:

a fourth contact plug connected to the third select gate line; and

a third wiring layer provided on the third contact plug and the fourth contact plug.