Semiconductor device and manufacturing method thereof
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsTamae Takano, Kiyoshi Kato, Hideaki Kuwabara
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Abstract
The invention provides a novel memory for which process technology is relatively simple and which can store multivalued information by a small number of elements. A part of a shape of the first electrode in the first storage element is made different from a shape of the first electrode in the second storage element, and thereby voltage values which change electric resistance between the first electrode and the second electrode are varied, so that one memory cell stores multivalued information over one bit. By partially processing the first electrode, storage capacity per unit area can be increased.
Claims15
A semiconductor device comprising:
- at least first and second storage elements, each having a first electrode, the first storage element comprising:
- the first electrode over an insulating surface;
- a second electrode over the first electrode;
- and
- a material layer interposed between the first and second electrodes;
- and
- a thin film transistor electrically connected to the first and second storage elements,
- wherein, in each of the first and second storage elements, an electrical resistance changes due to an application of a voltage thereto,
- wherein a voltage value at which the voltage changes in the first storage element is different from a voltage value at which the voltage changes in the second storage element, and
- wherein the second electrode of the first storage element is common to the second storage element.
A semiconductor device comprising:
- a first electrode over an insulating surface;
- a partition wall over the first electrode;
- a material layer over the partition wall and the first electrode;
- and
- a second electrode over the material layer,
- wherein a portion of the partition wall is provided between a first region over the first electrode and a second region over an end portion of the first electrode;
- wherein in the first region, at least the first electrode, the material layer, and the second electrode are overlapped with one another;
- and
- wherein in the second region, at least the material layer and the second electrode are overlapped with each other.
A semiconductor device including at least one memory cell, the memory cell comprising,
- at least a first storage element and a second storage element;
- wherein the first storage element and the second storage element include a common first electrode, a common second electrode, and a common material layer between the common first electrode and the common second electrode,
- wherein at least a part of a shape of the common first electrode in the first storage element is different from a shape of the common first electrode in the second storage element, and
- wherein a storage capacity per unit area of the first storage element is different from a storage capacity per unit area of the second storage element.
Dependencies are inferred from the claim text.