Patent ID: 6388915
Filing Date: 2002-05-14
Classification: G11C

Abstract:
A method for driving a semiconductor memory,said semiconductor memory including a memory cell block composed of a plurality of memory cells connected to one another in parallel and each including a ferroelectric capacitor for storing a data in accordance with displacement of polarization of a ferroelectric film thereof and a cell selecting transistor connected to said ferroelectric capacitor in series; a set line connected to a first common node of two common nodes included in said memory cell block, a reading voltage being applied to said set line; and a load capacitor connected to a second common node of the two common nodes for detecting displacement of polarization of the ferroelectric film of a selected ferroelectric capacitor selected from a plurality of ferroelectric capacitors included in said plurality of memory cells, the method comprising: a first step of turning on one of said cell selecting transistors serially connected to said data read ferroelectric capacitor and turning off the other of said cell selecting transistors serially connected to ferroelectric capacitors from which a data is not to be read among said plurality of ferroelectric capacitors, whereby connecting a first electrode of said data read ferroelectric capacitor to said set line through said first common node and connecting a second electrode of said data read ferroelectric capacitor to said load capacitor through said second common node; a second step of applying a reading voltage to said set line; and a third step of removing said reading voltage applied to said set line, wherein said reading voltage applied in the second step is set to such magnitude that displacement of polarization of the ferroelectric film of said data read ferroelectric capacitor is restored to displacement obtained before reading a data by removing said reading voltage in the third step.