FERROELECTRIC MEMORY DEVICE

摘要

A ferroelectrique capacitor used in a memory cell section of a ferroelectric memory device comprises a polarization P1 region having a film thickness (d) and an area S1, and a polarization P2 region which is a component in the P1 direction of oblique polarization P2 having only one electrode section and an area S2. The combined hysteresis characteristics of the polarizations P1 and P2 include a twisted hysteresis characteristic. When the memory state of the twisted hysteresis characteristic is "0" and "1", nondestructive readout is possible due to a back switching phenomenon. A ferroelectric memory device of another mode of this invention comprises a ferroelectric capacitor (11) which has a multiplex hysteresis characteristic having at least three stable polarization values attributed to the twisted hysteresis characteristic and is formed by sandwiching a ferroelectric material which stores multilevel voltages resulting from the multiplex hysteresis characteristic as information between electrode materials, dielectric capacitor (12) connected in series to the capacitor (11), and voltage-current converting element (16) which reads out the multilevel information stored in the capacitor (11).