Self-aligned resistive plugs for forming memory cell with phase change material
First Claim
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1. A memory cell for storage and retrieval of information in a memory device, comprising:
- volume of phase change material disposed in a semiconductor device and comprising a generally planar upper surface and a generally planar lower surface and a memory region comprising a portion of the volume of phase change material extending between an upper portion of the upper surface and a lower portion of the lower surface;
first high resistivity material at least partially overlying the volume of phase change material and comprising a first intermediate resistivity portion contacting the upper portion of the upper surface of the memory region; and
second high resistivity material at least partially underlying the volume of phase change material and comprising a second intermediate resistivity portion contacting the lower portion of the lower surface of the memory region;
wherein phase change material in the memory region and the first and second intermediate resistivity portions form an electrical path for storage and retrieval of information in the memory cell.
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Abstract
Memory devices are disclosed for storage and retrieval of information, wherein resistive plugs are provided above and below a phase change material to form a memory cell. The plugs may be formed by implanting regions in high resistivity material above and below a phase change material layer to lower the resistivity in the implanted regions.
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Citations
23 Claims
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1. A memory cell for storage and retrieval of information in a memory device, comprising:
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volume of phase change material disposed in a semiconductor device and comprising a generally planar upper surface and a generally planar lower surface and a memory region comprising a portion of the volume of phase change material extending between an upper portion of the upper surface and a lower portion of the lower surface;
first high resistivity material at least partially overlying the volume of phase change material and comprising a first intermediate resistivity portion contacting the upper portion of the upper surface of the memory region; and
second high resistivity material at least partially underlying the volume of phase change material and comprising a second intermediate resistivity portion contacting the lower portion of the lower surface of the memory region;
wherein phase change material in the memory region and the first and second intermediate resistivity portions form an electrical path for storage and retrieval of information in the memory cell. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
first conductive contact structure at least partially overlying the first intermediate resistivity portion of the first high resistivity material and electrically contacting the first intermediate resistivity portion; and
second conductive contact structure at least partially underlying the second intermediate resistivity portion of the second high resistivity material and electrically contacting the second intermediate resistivity portion;
wherein an applied voltage across the first and second conductive contact structures causes a current to flow in the phase change material in the memory region and the first and second intermediate resistivity portions.
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3. The memory cell of claim 2, wherein at least one of the first and second intermediate resistivity portions comprise high resistivity material implanted with at least one of boron, arsenic, and phosphorus, and wherein a resistivity associated with the at least one of the first and second intermediate resistivity portions is less than a resistivity associated with one of the first and second high resistivity materials.
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4. The memory cell of claim 3, wherein the memory region and the first and second intermediate resistivity portions are aligned along a vertical axis.
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5. The memory cell of claim 2, wherein the volume of phase change material comprises an electrically switchable chalcogenide alloy formed of antimony, tellurium, and germanium, wherein the first and second high resistivity materials comprise one of undoped polysilicon and amorphous silicon, and wherein at least one of the first and second intermediate resistivity portions comprise high resistivity material implanted with at least one of boron, arsenic, and phosphorus.
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6. The memory cell of claim 2, wherein the volume of phase change material is located in a generally horizontal plane and wherein the first and second intermediate resistivity portions are symmetrical with respect to one another about the plane.
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7. The memory cell of claim 1, wherein at least one of the first and second intermediate resistivity portions comprises high resistivity material implanted with at least one of boron, arsenic, and phosphorus, and wherein a resistivity associated with the at least one of the first and second intermediate resistivity portions is less than a resistivity associated with one of the first and second high resistivity materials.
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8. The memory cell of claim 1, wherein the memory region and the first and second intermediate resistivity portions are aligned along a vertical axis.
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9. The memory cell of claim 1, wherein the volume of phase change material comprises an electrically switchable chalcogenide alloy formed of antimony, tellurium, and germanium, wherein the first and second high resistivity materials comprise one of undoped polysilicon and amorphous silicon, and wherein at least one of the first and second intermediate resistivity portions comprises high resistivity material implanted with at least one of boron, arsenic, and phosphorus.
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10. The memory cell of claim 1, wherein the volume of phase change material is located in a generally horizontal plane and wherein the first and second intermediate resistivity portions are symmetrical with respect to one another about the plane.
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11. A memory device for storage and retrieval of information, comprising:
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an array of electrically programmable and erasable memory cells individually operative for storage and retrieval at least one data bit; and
means for reading and writing the array of memory cells;
wherein at least one of the memory cells comprises;
volume of phase change material disposed in a semiconductor device and comprising a generally planar upper surface and a generally planar lower surface and a memory region comprising a portion of the volume of phase change material extending between an upper portion of the upper surface and a lower portion of the lower surface;
first high resistivity material at least partially overlying the volume of phase change material and comprising a first intermediate resistivity portion contacting the upper portion of the upper surface of the memory region; and
second high resistivity material at least partially underlying the volume of phase change material and comprising a second intermediate resistivity portion contacting the lower portion of the lower surface of the memory region. - View Dependent Claims (12, 13, 14, 15)
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16. A method of fabricating a memory cell in a semiconductor memory device, comprising:
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providing a semiconductor substrate;
depositing a first conductive contact layer over the substrate;
depositing a first high resistivity layer over the first conductive contact layer;
depositing a volume of phase change material over the first high resistivity layer, the volume of phase change material comprising a memory region comprising a portion of the volume of phase change material extending between generally planar upper and lower surfaces of the volume of phase change material;
depositing a second high resistivity layer over the volume of phase change material;
depositing a second conductive contact layer over the second high resistivity layer;
forming a first intermediate resistivity portion in the first high resistivity layer substantially beneath the memory region; and
forming a second intermediate resistivity portion in the second high resistivity layer substantially above the memory region. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23)
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Specification