Patent ID: 7142445

Claim:
A ferroelectric memory device comprising: a plurality of wordlines disposed in parallel; a plurality of bitlines disposed in parallel and intersect the wordlines; a plurality of ferroelectric memory cells formed at intersections between the wordlines and the bitlines; a wordline driver which drives the wordlines; and a bitline driver which drives the bitlines, wherein: the wordline driver and the bitline driver switch an operation mode of the ferroelectric memory device to a first mode which is one of one of a data reading mode, a data rewriting mode and a data writing mode, by applying a voltage having a first polarity to at least one ferroelectric memory cell selected from the ferroelectric memory cells; and the wordline driver and the bitline driver switch the operation mode to a second mode in which the ferroelectric memory device prevents an imprint by applying a voltage having a second polarity which is the reverse of the first polarity to the selected ferroelectric memory cell, after the operation mode has been switched to the first mode at least once, the voltage of the second polarity causing no inversion data stored in the ferroelectric memory cells; wherein between the first and second modes, the wordline driver and the bitline driver switch the operation mode to an equalization mode in which potentials of one of the wordlines and one of the bitlines connected to the selected ferroelectric memory cell are equalized; the wordline driver supplies one of two types of selected potentials to one of the wordlines connected to the selected ferroelectric memory cell, and supplies one of two types of unselected potentials to another one of the wordlines connected to an unselected ferroelectric memory cell among the ferroelectric memory cells in the first mode; the bitline driver supplies the other of the two types of selected potentials to one of the bitlines connected to the selected ferroelectric memory cell, and supplies the other of the two types of unselected potentials to another one of the bitlines connected to the unselected ferroelectric memory cell in the first mode; the wordline driver supplies a potential used in the equalization mode to the wordlines in the second mode; and the bitline driver supplies one of the two types of the unselected potentials to one of the bitlines connected to the selected ferroelectric memory cell and supplies the potential used in the equalization mode to the other of the bitlines in the second mode.