Semiconductor memory device, method for driving the same and method for fabricating the same

摘要

Data is read out from a ferroelectric film with its remnant polarization associated with one of two possible logical states of the data and with a bias voltage applied to a control gate electrode over the ferroelectric film. The ferroelectric film creates either up or down remnant polarization. So the down remnant polarization may represent data "1" while the up or almost zero remnant polarization may represent data "0", for example. By regarding the almost zero remnant polarization state as representing data "0", a read current value becomes substantially constant in the data "0" state. As a result, the read accuracy improves. Also, if imprinting of one particular logical state (e.g., data "1") is induced in advance, then the read accuracy further improves.