Patent ID: 6771530
Filing Date: 2004-08-03
Classification: G11C,H01L

Abstract:
A method for driving a semiconductor memory composed of an MFS transistor including a field effect transistor having a gate electrode formed on a ferroelectric film or an MFIS transistor including a field effect transistor having a gate electrode formed on a multi-layer film of a ferroelectric film and a dielectric film, comprising the steps of:writing a data in said semiconductor memory by changing a polarized state of said ferroelectric film by applying a voltage to said gate electrode; and reading a data written in said semiconductor memory by detecting a current change appearing between a drain and a source of said field effect transistor by applying a voltage between the drain and the source of said field effect transistor with a voltage applied to said gate electrode, wherein magnitude of the voltage applied between the drain and the source of said field effect transistor in the step of reading a data is set within a range, such that a drain-source current of said field effect transistor increases as a drain-source voltage thereof increases under the condition that the voltage/current characteristics of said field effect transistor change due to a reduction in polarization and disappearance of charges after being programmed.