Semiconductor memory device

A semiconductor memory device comprising:

• a ferroelectric element composed of a ferroelectric material having one structure selected from an ABO3 crystal structure and an ABO3 perovskite structure, both of the ABO3 crystal structure and the ABO3 perovskite structure being composed of atoms A, atoms B and atoms O, an electric field applied to the ferroelectric element being controlled so that a position of each of the atoms B is relatively shifted for positions of the atoms A and the atoms O to store data at the stabilized positions as remanent polarization,
• wherein the ferroelectric element stores two-bit information by having total four stabilized positions of the atoms B, which include first stabilized two positions in a first direction and second stabilized two positions in a second direction perpendicular to the first direction.

A semiconductor memory device comprising:

• a ferroelectric element composed of a ferroelectric material having one structure selected from an ABxC (1−x) O3 crystal structure and an ABxC (1−x) O3 perovskite structure, both of the ABxC (1−x) O3 crystal structure and the ABxC (1−x) O3 perovskite structure being composed of at least atoms A, atoms B, atoms C and atoms O, an electric field applied to the ferroelectric element being controlled to relatively shift a position of one atom selected from the atoms B and atoms C with respect to positions of the atoms A and atoms O and permit data to be stored in stabilized positions as remanent polarization,
• wherein the ferroelectric element stores two-bit information by having total four stabilized positions of one atom selected from the atoms B and atoms C, which include first stabilized two positions in a first direction and second stabilized two positions in a second direction perpendicular to the first direction.

A semiconductor memory device comprising:

• a ferroelectric element having one structure selected from an ABO3 crystal structure and an ABO3 perovskite structure, both of the ABO3 crystal structure and the ABO3 perovskite structure being composed of at least atoms A, atoms B and atoms O, an electric field applied to the ferroelectric element being controlled to relatively shift a position of the atoms B with respect to positions of the atoms A and atoms O and permit data to be stored in stabilized positions as remanent polarization,
• wherein the ferroelectric element stores multi-bit information by having total six stabilized positions of the atoms B, which include first stabilized two positions in a first direction, second stabilized two positions in a second direction perpendicular to the first direction and third stabilized two positions in a third direction perpendicular to the first and second directions.

A semiconductor memory device comprising:

• a ferroelectric element having one structure selected from an ABxC (1−x) O3 crystal structure and an ABxC (1−x) O3 perovskite structure, both of the ABxC (1−x) O3 crystal structure and the ABxC (1−x) O3 perovskite structure being composed of at least atoms A, atoms B, atoms C and atoms O, an electric field applied to the ferroelectric element being controlled to relatively shift a position of one atom selected from the atoms B and atoms C with respect to positions of the atoms A and atoms O and permit data to be stored in stabilized positions as remanent polarization,
• wherein the ferroelectric element stores multi-bit information by having total six stabilized positions of one atom selected from the atoms B and atoms C, which include two stabilized positions in a first direction, two stabilized positions in a second direction perpendicular to the first direction and two stabilized positions in a third direction perpendicular to the first and second directions.

A semiconductor memory device comprising:

• a ferroelectric element, an electric field applied to the ferroelectric element being controlled to relatively shift a position of a first atom with respect to a position of another atom and permit data to be stored in stabilized positions as remanent polarization,
• wherein the ferroelectric element stores multi-bit information by having total six stabilized positions of the first atom, which include first stabilized two positions in a first direction, second stabilized two positions in a second direction perpendicular to the first direction and third stabilized two positions in a third direction perpendicular to the first and second directions.

A semiconductor memory device which stores information of at least three values, comprising:

• a ferroelectric element, and
• at least three electrodes in contact with the ferroelectric element.

A semiconductor memory device comprising:

• a ferroelectric element, and
• at least three electrodes in contact with the ferroelectric element,
• wherein at least one of the electrodes is connected to a data readout line via a transistor.

A semiconductor memory device comprising:

• a ferroelectric element,
• wherein a first atom is shifted to at least three positions on a two-dimensional plane in the ferroelectric element to hold data of at least three values.

A semiconductor memory device comprising:

• a ferroelectric element,
• wherein a first atom is shifted to at least three positions on a three-dimensional plane in the ferroelectric element to hold data of at least three values.

A semiconductor memory device comprising:

• a ferroelectric element, and
• first, second, third and fourth electrodes,
• wherein the first and second electrodes are respectively connected to source and drain terminals of a first transistor and the third and fourth electrodes are respectively connected to source and drain terminals of a second transistor to configure one memory cell and information of at least two bits is stored in the memory cell.