Method for driving a nonvolatile semiconductor memory device

A method for driving a nonvolatile semiconductor memory device having a semiconductor layer having a channel and source/drain regions provided on both sides of the channel, a first insulating film provided on the channel, a floating electrode provided on the first insulating film, a second insulating film provided on the floating electrode, and a gate electrode provided on the second insulating film, the nonvolatile semiconductor memory device changing its data memory state by injection of charges into the floating electrode,

• the method comprising, to achieve a state in which charges having a first polarity are injected into the floating electrode:
• providing a fifth potential difference between the semiconductor layer and the gate electrode to inject charges having the first polarity into the floating electrode;
• and
• subsequently providing a sixth potential difference between the semiconductor layer and the gate electrode to inject charges having a second polarity opposite to the first polarity into the second insulating film.

A nonvolatile semiconductor memory device comprising:

• a semiconductor layer having a channel and source/drain regions provided on both sides of the channel;
• a first insulating film provided on the channel;
• a floating electrode provided on the first insulating film;
• a second insulating film provided on the floating electrode;
• a gate electrode provided on the second insulating film;
• and
• a control circuit controlling its data memory state by injection of charges into the floating electrode,
• the control circuit being configured to perform, to achieve a state in which charges having a first polarity are injected into the floating electrode:
• providing a first potential difference between the semiconductor layer and the gate electrode to inject charges having the first polarity into the second insulating film;
• subsequently providing a second potential difference between the semiconductor layer and the gate electrode to inject charges having a second polarity opposite to the first polarity into the second insulating film;
• and
• subsequently providing a third potential difference between the semiconductor layer and the gate electrode to inject charges having the first polarity into the floating electrode.

A nonvolatile semiconductor memory device comprising:

• a semiconductor layer having a channel and source/drain regions provided on both sides of the channel;
• a first insulating film provided on the channel;
• a floating electrode provided on the first insulating film;
• a second insulating film provided on the floating electrode;
• a gate electrode provided on the second insulating film;
• and
• a control circuit controlling its data memory state by injection of charges into the floating electrode,
• the control circuit being configured to perform, to achieve a state in which charges having a first polarity are injected into the floating electrode:
• providing a fifth potential difference between the semiconductor layer and the gate electrode to inject charges having the first polarity into the floating electrode;
• and
• subsequently providing a sixth potential difference between the semiconductor layer and the gate electrode to inject charges having a second polarity opposite to the first polarity into the second insulating film.