Sidewall structured switchable resistor cell

• US 20090256129A1
• Filed: 06/30/2008
• Published: 10/15/2009
• Est. Priority Date: 04/11/2008
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk 3D LLC (Western Digital Corporation)
• Inventors: Scheuerlein, Roy E.
• Granted Patent: US 7,812,335 B2
• Time in Patent Office: Days
• US Class Current: 257/4
• CPC Class Codes: H10B 63/20 comprising selection components having two electrodes, e.g. diodes
• CPC Class Codes: H10B 63/22 of the metal-insulator-metal type
• 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: H10N 70/021 Formation of switching materials, e.g. deposition of layers
• CPC Class Codes: H10N 70/023 by chemical vapor deposition, e.g. MOCVD, ALD
• CPC Class Codes: H10N 70/026 by physical vapor deposition, e.g. sputtering
• CPC Class Codes: H10N 70/068 by processes specially adapted for achieving sub-lithographic dimensions, e.g. using spacers
• 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 70/245 the species being metal cations, e.g. programmable metallization cells
• CPC Class Codes: H10N 70/8265 on sidewalls of dielectric structures, e.g. mesa-shaped or cup-shaped devices
• 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 method of making a memory device includes forming a first conductive electrode, forming an insulating structure over the first conductive electrode, forming a resistivity switching element on a sidewall of the insulating structure, forming a second conductive electrode over the resistivity switching element, and forming a steering element in series with the resistivity switching element between the first conductive electrode and the second conductive electrode, wherein a height of the resistivity switching element in a first direction from the first conductive electrode to the second conductive electrode is greater than a thickness of the resistivity switching element in second direction perpendicular to the first direction.

Claims

1. A method of making a memory device, comprising:

forming a first conductive electrode;

forming an insulating structure over the first conductive electrode;

forming a resistivity switching element on a sidewall of the insulating structure;

forming a second conductive electrode over the resistivity switching element; and

forming a steering element in series with the resistivity switching element between the first conductive electrode and the second conductive electrode;

wherein a height of the resistivity switching element in a first direction from the first conductive electrode to the second conductive electrode is greater than a thickness of the resistivity switching element in a second direction perpendicular to the first direction.

2. The method of claim 1, further comprising:

forming an insulating layer over the resistivity switching element; and

planarizing the insulating layer to expose an upper surface of the resistivity switching element before the step of forming the second conductive electrode layer.

3. The method of claim 1, wherein the resistivity switching element is a metal oxide layer located on a sidewall of the insulating structure.

4. The method of claim 1, wherein the resistivity switching element is selected from an antifuse dielectric, a fuse, a polysilicon memory effect material, a metal oxide or switchable complex metal oxide material, a carbon nanotube material, a graphene switchable resistance material, carbon resistivity switching material, a phase change material, a conductive bridge element, an electrolyte switching material, or a switchable polymer material.

5. The method of claim 1, wherein the resistivity switching element comprises a metal oxide formed by depositing a metal or metal nitride layer on the sidewall of the insulating structure and oxidizing the metal or metal nitride layer to form a metal oxide or metal oxynitride layer.

6. The method of claim 1, further comprising forming a trench in an insulating layer to form the insulating structure, such that the first conductive electrode is exposed on a bottom of the trench, and the resistivity switching element is formed on the sidewall of the trench insulating structure and in contact with the first conductive electrode.

7. The method of claim 1, further comprising patterning an insulating layer to form insulating rail shaped insulating structure, such that the first conductive electrode is exposed between adjacent insulating rails, and the resistivity switching element is formed on the sidewall of at least one insulating rail and in contact with the first conductive electrode.

8. The method of claim 7, further comprising filling the space between the insulating rails with an insulating filler material.

9. The method of claim 1, further comprising patterning an insulating layer to form a pillar shaped insulating structure, such that the resistivity switching element is formed on the sidewall of the pillar shaped insulating structure.

10. The method of claim 1, wherein the steering element comprises a diode located above the resistivity switching element.

11. The method of claim 1, wherein the steering element comprises a diode located below the resistivity switching element.

12. A memory device, comprising:

a first conductive electrode;

an insulating structure;

a resistivity switching element located on a sidewall of the insulating structure;

a second conductive electrode located over the resistivity switching element; and

a steering element located in series with the resistivity switching element between the first conductive electrode and the second conductive electrode;

wherein a height of the resistivity switching element in a first direction from the first conductive electrode to the second conductive electrode is greater than a thickness of the resistivity switching element in second direction perpendicular to the first direction.

13. The device of claim 12, wherein the steering element comprises a diode located above the resistivity switching element.

14. The device of claim 12, wherein the steering element comprises a diode located below the resistivity switching element

15. The device of claim 12, wherein the steering element comprises a pillar shaped p-i-n diode separated from the resistivity switching element by a conductive barrier layer.

16. The device of claim 12, wherein the resistivity switching element is a metal oxide layer located on a sidewall of the insulating structure.

17. The device of claim 12, wherein the resistivity switching element is selected from an antifuse dielectric, a fuse, a polysilicon memory effect material, a metal oxide or switchable complex metal oxide material, a carbon nanotube material, a graphene switchable resistance material, carbon resistivity switching material, a phase change material, a conductive bridge element, an electrolyte switching material, or a switchable polymer material.

18. The device of claim 12, wherein:

the insulating structure comprises a trench in an insulating layer; and

the resistivity switching element is located on the sidewall of the trench in the insulating layer and in contact with the first conductive electrode exposed on a bottom of the trench in the insulating layer.

19. The device of claim 12, wherein the insulating structure comprises a plurality of insulating rails, and the resistivity switching element is located on the sidewall of at least one insulating rail and in contact with the first conductive electrode exposed between adjacent rails.

20. The device of claim 19, wherein a space between the plurality of insulating rails is filled with an insulating filler material and each insulating rail is partially misaligned with the first conductive electrode and the steering element such that the resistivity switching element is located in contact with the first conductive electrode and the steering element.

21. The device of claim 12, wherein the insulating structure comprises an insulating pillar, such that the resistivity switching element is formed on at least one sidewall of the insulating pillar.

22. The device of claim 12, wherein the resistivity switching element has height greater than 10 nm and a thickness less than 10 nm.

23. A method of making a memory device, comprising

forming a first conductive electrode;

forming at least one diode layer over the first conductive electrode;

forming at least one insulating template layer over the diode layer;

forming a hard mask pattern over the template layer;

etching the template layer using the hard mask pattern as a mask;

reducing a width of the template layer to form an insulating pillar;

depositing a metal oxide resistivity switching layer over a sidewall of the insulating pillar;

etching the diode layer using the hard mask pattern as a mask to form a pillar diode steering element; and

forming a second conductive electrode in contact with the metal oxide resistivity switching layer.

24. The method of claim 23, wherein:

the step of reducing the width is performed by isotropic etching of the insulating template layer to undercut the hard mask pattern; and

the step of depositing the metal oxide is performed by atomic layer deposition.

25. The method of claim 24, further comprising removing the hard mask pattern in contact with the resistivity switching layer prior to forming the second conductive electrode.