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US 7,254,059 B2Granted
Multilevel phase-change memory element and operating method
AssigneeIndustrial Technology Research Institut
InventorsChien-Ming Li, Wen-Han Wang, Kuei-Hung Shen
Life of this patent
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Abstract
A multilevel phase change memory element and operating method and electrodes, which are configured in a parallel structure to form a memory cell. A voltage-drive mode is employed to control and drive the memory element such that multilevel memory states may be achieved by imposing different voltage levels. The provided multilevel phase-change memory element has more bits and higher capacity than that of a memory element with a single phase-change layer.
Claims23
A phase change memory element comprising:
- a first phase change layer either in a crystalline state or in an amorphous state;
- a second phase change layer either in a crystalline state or in an amorphous state;
- a first top electrode and a second top electrode formed on one surface of the first phase change layer and the second phase change layer respectively, the first and second top electrodes being electrically connected in parallel for delivering electrical signals to change states of the first phase change layer and the second phase change layer;
- and
- at least one bottom electrode connected to further surfaces of the first phase change layer and the second phase change layer respectively, the at least one bottom electrode being electrically connected to the first and second phase change layers in parallel and leading to a selecting component.
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A phase change memory element, comprising;
- a first phase change layer that is either in a crystalline state or in an amorphous state, the first phase change layer having top and bottom ends;
- a second phase change layer that is either in a crystalline state or in an amorphous state, the first phase change layer having top and bottom ends;
- top means for permanently electrically connecting the top ends of the first and second phase change layers;
- and
- bottom means for permanently electrically connecting the bottom ends of the first and second phase change layers.
2 more elements
Dependencies are inferred from the claim text.