Nonvolatile semiconductor memory device

1. A nonvolatile semiconductor memory device, comprising:

a memory cell array including a plurality of memory cells connected in series to form a memory string;

a plurality of word lines, each word line connected to a control gate of a respective memory cell in the memory string; and

a control circuit configured to control a data write to the memory cell array, wherein

the control circuit applies:

a program voltage to a selected word line,

a first write pass voltage, which is lower than the program voltage, to a first group of non-selected word lines, the first group comprising word lines adjacent to the selected word line, and

a second write pass voltage, which is higher than the first write pass voltage, to a second group of non-selected word lines, the second group not including the first group; and

the control circuit sets the first write pass voltage to a first level when the selected word line is connected to a memory cell at an end of the memory string and to a second level when the selected word line is not connected to a memory cell at either end of the memory string, the first level not equal to the second level.

2. The nonvolatile semiconductor memory device according to claim 1 , wherein the first level of the first write pass voltage is higher than the second level of the first write pass voltage.

3. The nonvolatile semiconductor memory device according to claim 1 , wherein the first level of the first write pass voltage is lower than the second level of the first write pass voltage.

4. The nonvolatile semiconductor memory device according to claim 1 , wherein the control circuit increases the first level or the second level of the first write pass voltage in response to a result of a write verifying operation.

5. The nonvolatile semiconductor memory device according to claim 2 , wherein the control circuit increases the second level of the first write pass voltage in response to a result of a write verifying operation.

6. The nonvolatile semiconductor memory device according to claim 5 , wherein the control circuit maintains the first level of the first write pass voltage in response to the result of the write verifying operation.

7. The nonvolatile semiconductor memory device according to claim 3 , wherein the control circuit increases the first level of the first write pass voltage in response to a result of a write verifying operation.

8. The nonvolatile semiconductor memory device according to claim 7 , wherein the control circuit maintains the second level of the first write pass voltage in response to the result of the write verifying operation.

9. The nonvolatile semiconductor memory device according to claim 1 , wherein the control circuit sets the first or the second level of the first write pass voltage based on an implementation time of a write operation or an erase operation.

10. The nonvolatile semiconductor memory device according to claim 2 , further comprising:

a first dummy memory cell connected to one end of the memory string;

a first selective transistor connected to the first dummy memory cell;

wherein control gates of the memory cells between the ends of the memory string are spaced at a first distance from each adjacent memory cell, a control gate of the first dummy memory cell is spaced at second distance from the control gate of the memory cell to which said dummy memory cell is connected, and the control gate of the first dummy memory cell is spaced at a third distance from a control gate of the first selective transistor, the third distance is greater than the first distance, and the first distance is greater than the second distance.

11. The nonvolatile semiconductor memory device according to claim 10 , wherein the first distance is at least twenty percent greater than the second distance, and the third distance is at least twenty percent greater than first distance.

12. The nonvolatile semiconductor memory device according to claim 3 , further comprising:

a first dummy memory cell connected to one end of the memory string;

a first selective transistor connected to the first dummy memory cell;

wherein control gates of the memory cells between the ends of the memory string are spaced at a first distance from each adjacent memory cell, a control gate of the first dummy memory cell is spaced at second distance from the control gate of the memory cell to which said dummy memory cell is connected, and the control gate of the first dummy memory cell is spaced at a third distance from a control gate of the first selective transistor, the second distance is greater than the first distance, and the first distance is greater than the third distance.

13. A nonvolatile semiconductor memory device, comprising:

a memory cell array including a plurality of memory cells connected in series to form a memory string;

a plurality of word lines, each word line connected to a control gate of a respective memory cell in the memory string;

a first dummy memory cell connected to a first end of the memory string;

a second dummy memory cell connected to a second end of the memory string; and

a control circuit configured to control a data write to the memory cell array, wherein the control circuit applies:

a program voltage to a selected word line,

a first write pass voltage, which is lower than the program voltage, to a first group of non-selected word lines, the first group comprising word lines adjacent to the selected word line, and

a second write pass voltage, which is higher than the first write pass voltage, to a second group of non-selected word lines, the second group not including the first group; and

the control circuit sets the first write pass voltage to a first level when the selected word line is connected to a memory cell at an end of the memory string and to a second level when the selected word line is not connected to a memory cell at either end of the memory string, the first level not equal to the second level.

14. The nonvolatile semiconductor memory device according to claim 13 , further comprising:

a first dummy memory cell word line connected to a control gate of the first dummy memory cell;

a second dummy memory cell word line connected to a control gate of the second dummy memory cell;

a first selective transistor connected to the first dummy memory cell; and

a second selective transistor connected to the second dummy memory cell

wherein the first write pass voltage is applied to the first dummy memory cell word line when the selected word line is connected to the memory cell on the first end of the memory string.

15. The nonvolatile semiconductor memory device according to claim 14 , wherein the first level of the first write pass voltage is higher than the second level of the first write pass voltage.

16. The nonvolatile semiconductor memory device according to claim 14 , wherein the first level of the first write pass voltage is lower than the second level of the first write pass voltage.

17. The nonvolatile semiconductor memory device according to claim 15 , wherein the control circuit increases the second level of the first write pass voltage in response to a result of a write verifying operation.

18. The nonvolatile semiconductor memory device according to claim 17 , wherein the control circuit maintains the first level of the first write pass voltage in response to the result of the write verifying operation.

19. The nonvolatile semiconductor memory device according to claim 16 , wherein the control circuit increases the first level of the first write pass voltage in response to a result of a write verifying operation.

20. A method of controlling a data write to a memory cell array including a plurality of memory cells connected in series to form a memory string, and a plurality of word lines, each word line connected to a control gate of a respective memory cell in the memory string, the method comprising:

selecting a word line connected to the control gate of a memory cell in the memory string;

applying a program voltage to the selected word line;

applying a first pass voltage to word lines adjacent to the selected word line; and

applying a second pass voltage to the word lines not adjacent to the selected word line, wherein

the first pass voltage is different from the second pass voltage, and both the first and the second pass voltages are less than the program voltage,

when the selected word line is connected to a memory cell at the end of the memory string, setting the first pass voltage to a first level; and

when the selected word line is not connected to a memory cell at the end of the memory string, setting the first pass voltage to a second level, the first level not equal to the second level.