Method of operating semiconductor memory device

A method of operating a semiconductor memory device, comprising:

• coupling cell strings, comprising memory cells having gates coupled to respective word lines, to respective bit lines;
• discharging channel regions of third cell strings including third memory cells and precharging channel regions of remaining cell strings;
• applying a program pass voltage to unselected word lines;
• applying a program voltage of a third level to a selected word line in order to raise threshold voltages of the third memory cells;
• decreasing a level of the program voltage from the third level to a second level and discharging channel regions of second cell strings including second memory cells in order to raise threshold voltages of the second memory cells;
• decreasing a level of the program voltage from the second level to a first level and discharging channel regions of first cell strings including first memory cells in order to raise threshold voltages of the first memory cells;
• and
• changing a bit line voltage of bit lines coupled to the second or first cell strings to a program permission level in order to discharge the channel regions of the first or second cell strings in a state in which the cell string is disconnected from the bit line.

A method of operating a semiconductor memory device, comprising:

• coupling cell strings, comprising memory cells having gates coupled to respective word lines, to respective bit lines;
• discharging channel regions of third cell strings including third memory cells and precharging channel regions of remaining cell strings;
• applying a program pass voltage to unselected word lines;
• applying a program voltage of a third level to a selected word line in order to raise threshold voltages of the third memory cells;
• decreasing a level of the program voltage from the third level to a second level and discharging channel regions of second cell strings including second memory cells in order to raise threshold voltages of the second memory cells;
• and
• decreasing a level of the program voltage from the second level to a first level and discharging channel regions of first cell strings including first memory cells in order to raise threshold voltages of the first memory cells,
• wherein the program pass voltage is increased whenever the channel regions are discharged.

A method of operating a semiconductor memory device, comprising:

• coupling cell strings, comprising memory cells having gates coupled to respective word lines, to respective bit lines;
• discharging channel regions of third cell strings including third memory cells and precharging channel regions of remaining cell strings;
• applying a program pass voltage to unselected word lines;
• applying a program voltage of a third level to a selected word line in order to raise threshold voltages of the third memory cells;
• decreasing a level of the program voltage from the third level to a second level and discharging channel regions of second cell strings including second memory cells in order to raise threshold voltages of the second memory cells;
• and
• decreasing a level of the program voltage from the second level to a first level and discharging channel regions of first cell strings including first memory cells in order to raise threshold voltages of the first memory cells,
• wherein a program inhibition voltage applied to the bit lines in order to precharge the channel regions is increased whenever the channel regions are discharged.