Ferroelectric memory sensing method using distinct read and write voltages

摘要

A method of operating a nonvolatile ferroelectric memory cell including a polarized ferroelectric capacitor includes the steps of reading and restoring a first polarization state of the ferroelectric capacitor at a voltage not sufficient to fully saturate the ferroelectric capacitor, but sufficient to release a detectable amount of charge corresponding to the first polarization state. Writing a second polarization state in the ferroelectric capacitor is performed at a voltage sufficient to fully saturate the ferroelectric capacitor. During a read and restore operation, the plate line of the memory cell is pulsed with first and second voltage pulses that each have a voltage magnitude less than the normal five volt logic pulse, for example four volts. During a write operation, the plate line of the memory cell is pulsed with a voltage that has a magnitude greater than the normal five volt logic pulse, for example six to seven volts.