Resistance-Switching Memory Cell With Multiple Raised Structures In A Bottom Electrode

• US 20150333105A1
• Filed: 07/23/2015
• Published: 11/19/2015
• Est. Priority Date: 02/14/2013
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk 3D LLC (Western Digital Corporation)
• Inventors: Matamis, George, Kai, James K., Purayath, Vinod R., Zhang, Yuan, Chien, Henry
• Granted Patent: US 9,466,644 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H10B 63/80 Arrangements comprising multiple bistable or multi-stable switching components of the same type on a plane parallel to the substrate, e.g. cross-point arrays
• CPC Class Codes: H10B 63/84 arranged in a direction perpendicular to the substrate, e.g. 3D cell arrays
• CPC Class Codes: H10N 70/011 Manufacture or treatment of multistable switching devices
• CPC Class Codes: H10N 70/063 by etching of pre-deposited switching material layers, e.g. lithography
• CPC Class Codes: H10N 70/20 Multistable switching devices, e.g. memristors
• CPC Class Codes: H10N 70/231 based on solid-state phase change, e.g. between amorphous and crystalline phases, Ovshinsky effect
• CPC Class Codes: H10N 70/826 adapted for essentially vertical current flow, e.g. sandwich or pillar type devices
• CPC Class Codes: H10N 70/841 Electrodes
• CPC Class Codes: H10N 70/8418 adapted for focusing electric field or current, e.g. tip-shaped
• CPC Class Codes: H10N 70/8828 Tellurides, e.g. GeSbTe
• CPC Class Codes: H10N 70/883 Oxides or nitrides
• CPC Class Codes: H10N 70/8833 Binary metal oxides, e.g. TaOx
• CPC Class Codes: H10N 70/8836 Complex metal oxides, e.g. perovskites, spinels
• CPC Class Codes: H10N 70/8845 Carbon or carbides

Abstract

A reversible resistance-switching memory cell has multiple narrow, spaced apart bottom electrode structures. The raised structures can be formed by coating a bottom electrode layer with nano-particles and etching the bottom electrode layer. The raised structures can be independent or joined to one another at a bottom of the bottom electrode layer. A resistance-switching material is provided between and above the bottom electrode structure, followed by a top electrode layer. Or, insulation is provided between and above the bottom electrode structures, and the resistance-switching material and top electrode layer are above the insulation. Less than one-third of a cross-sectional area of each resistance-switching memory cell is consumed by the one or more raised structures. When the resistance state of the memory cell is switched, there is a smaller area in the bottom electrode for a current path, so the switching resistance is higher and the switching current is lower.

Claims

1. A resistance-switching memory cell, comprising:

a substrate;

a bottom electrode layer above the substrate, the bottom electrode layer comprising a plurality of raised structures;

a resistance-switching material, a top of each raised structure of the plurality of raised structures is in contact with the resistance-switching material;

a top electrode above the resistance-switching material; and

an insulating material adjacent to and between the plurality of raised structures, wherein a top of the insulating material is below the top of each raised structure of the plurality of raised structures and the resistance-switching material extends above the plurality of raised structures and the insulating material.

2. The resistance-switching memory cell of claim 1, wherein:

the top of the insulating material is above a bottom of each raised structure of the plurality of raised structures.

3. The resistance-switching memory cell of claim 1, wherein:

less than one-third of a cross-sectional area of the resistance-switching memory cell is consumed by the plurality of raised structures.

4. The resistance-switching memory cell of claim 1, wherein:

a top surface of the insulating material is adjacent to a bottom surface of the resistance-switching material.

5. The resistance-switching memory cell of claim 1, wherein:

the plurality of raised structures are spaced apart from one another in a plurality of rows.

6. The resistance-switching memory cell of claim 1, wherein:

the plurality of raised structures are spaced apart from one another in a first direction and in a second direction which is perpendicular to the first direction.

7. The resistance-switching memory cell of claim 1, wherein:

the plurality of the raised structures are not joined to one another.

8. The resistance-switching memory cell of claim 1, wherein:

the plurality of the raised structures are joined to one another at a bottom of the bottom electrode layer.

9. The resistance-switching memory cell of claim 1, wherein:

the bottom electrode layer comprises doped polysilicon.

10. The resistance-switching memory cell of claim 1, wherein:

the resistance-switching material comprises a phase change material.

11. The resistance-switching memory cell of claim 1, wherein:

the resistance-switching material comprises a metal oxide.

12. A resistance-switching memory cell, comprising:

a substrate;

a plurality of raised structures on the substrate, the plurality of raised structures comprise doped polysilicon;

a resistance-switching material which extends above the plurality of raised structures and is in contact with the plurality of raised structures;

an electrode above the resistance-switching material; and

an insulating material between the plurality of raised structures, wherein the insulating material is below the resistance-switching material.

13. The resistance-switching memory cell of claim 12, wherein:

the plurality of the raised structures are not joined to one another; and

the insulating material extends from a bottom of the resistance-switching material to a bottom of the plurality of the raised structures.

14. The resistance-switching memory cell of claim 12, wherein:

each raised structure of the plurality of raised structures has a bottom portion;

the bottom portions are joined to one another; and

the insulating material extends from a bottom of the resistance-switching material to the bottom portions of the plurality of the raised structures.

15. The resistance-switching memory cell of claim 12, wherein:

a top surface of the insulating material is adjacent to a bottom surface of the resistance-switching material.

16. A resistance-switching memory device, comprising:

a substrate;

a bottom wiring layer on the substrate comprising spaced apart wires; and

a plurality of resistance-switching memory cells formed on the substrate and aligned with the spaced apart wires of the bottom wiring layer, wherein each resistance-switching memory cell comprises;

a plurality of raised structures in a bottom electrode layer above the substrate, wherein each raised structure of the plurality of raised structures has a top, and the plurality of raised structures are spaced apart from one another in a first direction and in a second direction which is perpendicular to the first direction,

a resistance-switching material, wherein a top of each raised structure of the plurality of raised structures is in contact with the resistance-switching material;

a top electrode above the resistance-switching material; and

an insulating material between the plurality of raised structures, wherein a top of the insulating material is at a height which is below a height of the top of each raised structure of the plurality of raised structures, and the resistance-switching material extends above the plurality of raised structures and the insulating material.

17. The resistance-switching memory device of claim 16, further comprising:

a top wiring layer comprising spaced apart wires aligned with, and in electrical contact with, rows of the top electrodes.

18. The resistance-switching memory device of claim 16, further comprising:

a top wiring layer comprising spaced apart wires aligned with rows of the resistance-switching memory cells, the top electrodes are provided by portions of the spaced apart wires.

19. The resistance-switching memory device of claim 16, wherein:

the resistance-switching material of each of the resistance-switching memory cells are separated from one another.

20. The resistance-switching memory device of claim 16, wherein:

the resistance-switching memory cells as formed as pillars which are spaced apart from one another.