Amorphous carbon resistive memory element with lateral heat dissipating structure

• US 9,640,759 B1
• Filed: 11/25/2015
• Issued: 05/02/2017
• Est. Priority Date: 11/25/2015
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Curioni, Alessandro, Koelmans, Wabe W., Sebastian, Abu, Zipoli, Federico
• Primary Examiner(s): Dinh, Son
• Application Number:
  US14/951,489
• Publication Number:
  US 20170148984A1
• Time in Patent Office: 524 Days
• Field of Search: 365148, 365163
• CPC Class Codes: G11C 13/0002 using resistive RAM [RRAM] elements
• CPC Class Codes: G11C 13/0069 Writing or programming circuits or methods
• CPC Class Codes: G11C 2013/0078 Write using current through the cell
• CPC Class Codes: G11C 2213/35 Material including carbon, e.g. graphite, grapheme
• CPC Class Codes: G11C 2213/52 Structure characterized by the electrode material, shape, etc.
• CPC Class Codes: H10N 70/021 Formation of switching materials, e.g. deposition of layers
• CPC Class Codes: H10N 70/041 Modification of switching materials after formation, e.g. doping shaping H10N70/061
• CPC Class Codes: H10N 70/063 by etching of pre-deposited switching material layers, e.g. lithography
• CPC Class Codes: H10N 70/066 by filling of openings, e.g. damascene method
• 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 70/235 between different crystalline phases, e.g. cubic and hexagonal
• CPC Class Codes: H10N 70/826 adapted for essentially vertical current flow, e.g. sandwich or pillar type devices
• CPC Class Codes: H10N 70/828 Current flow limiting means within the switching material region, e.g. constrictions
• CPC Class Codes: H10N 70/841 Electrodes
• CPC Class Codes: H10N 70/861 Thermal details
• CPC Class Codes: H10N 70/8613 Heating or cooling means other than resistive heating electrodes, e.g. heater in parallel
• CPC Class Codes: H10N 70/8845 Carbon or carbides

Abstract

A resistive memory element is provided having a layer structure. The layer structure includes two layers forming two electrically conductive electrodes, respectively, a resistively switchable material sandwiched between the two layers forming the two electrodes, and in electrical connection therewith, and a confining material. The resistively switchable material is laterally confined within the confining material, between the two layers forming the electrodes. The confining material is sufficiently electrically insulating for an electric signal applied between the two conductive electrodes to change a resistance state of the memory element in operation. The confining material has a thermal conductivity greater than 0.5 W/(m·K), and preferably greater than or equal to 30 W/(m·K). The resistively switchable material is an amorphous compound comprising carbon, which has a maximal lateral dimension, along a direction parallel to an average plane of the two layers forming the electrodes, that is less than 60 nm.

Claims

1. A resistive memory element having a layer structure, the layer structure comprising:

two layers forming two electrically conductive electrodes, respectively;

a resistively switchable material, sandwiched between the two layers forming the two electrodes, and in electrical connection therewith; and

a confining material, the resistively switchable material laterally confined within the confining material,

wherein;

the confining material

is sufficiently electrically insulating for an electric signal applied between the two conductive electrodes to change a resistance state of the memory element, in operation; and

has a thermal conductivity greater than 0.5 W/(m·

K), and

the resistively switchable material is an amorphous compound comprising carbon, which has a maximal lateral dimension, along a direction parallel to an average plane of the two layers forming the two electrodes, that is less than 60 nm.

2. The resistive memory element according to claim 1, wherein the confining material has a thermal conductivity greater than or equal to 30 W/(m·

K).

3. The resistive memory element according to claim 2, wherein the confining material comprises at least one of SiC, TiC, BN, AlN, SiN, BeO, BP, BeS, GaN, Si, AlP, GaP, diamond and graphene.

4. The resistive memory element according to claim 2, wherein the maximal lateral dimension of the resistively switchable material is less than 30 nm.

5. The resistive memory element according to claim 4, wherein the memory element is configured such that one of the electrodes has a maximal lateral dimension that is substantially less than the maximal lateral dimension of the resistively switchable material at a level of an interface between said one of the electrode and the resistively switchable material.

6. The resistive memory element according to claim 1, further comprising an additional electrically conducting material, arranged to further dissipate heat laterally, between the electrodes, the confining material being in contact with the additional electrically conducting material and shaped so as to electrically insulate each of the electrodes and the resistively switchable material from the additional electrically conducting material.

7. The resistive memory element according to claim 6, wherein the additional electrically conducting material has a thermal conductivity greater than or equal to 40 W/(m·

K).

8. The resistive memory element according to claim 1, wherein the resistively switchable material is laterally confined by a stiffening material, which itself is laterally confined by said confining material, wherein the stiffening material has a Knoop hardness that is greater than the Knoop hardness of the confining material.

9. The resistive memory element according to claim 8, wherein the stiffening material comprises titanium carbide.

10. The resistive memory element according to claim 1, wherein the resistively switchable material exhibits a lateral density gradient, such that a density of the resistively switchable material close to the confining material is greater than a density at the center of the resistively switchable material.

11. The resistive memory element according to claim 1, wherein the resistive switching material is etched at a level of an interface between one of each of the two electrodes, so as to be hollowed inward.

12. The resistive memory element according to claim 1, wherein the resistively switchable material is in direct contact with each of:

the electrodes; and

one of the laterally confining layer and a stiffening material laterally confined by the confining layer.

13. The resistive memory element according to claim 1, wherein the amorphous carbon compound comprises more than 35 at. % sp³ C atoms when the resistively switchable material is in its pristine state.

14. The resistive memory element according to claim 1, wherein the amorphous carbon compound comprises more than 50 at. % sp³ C atoms when the resistively switchable material is in its pristine state.

15. The resistive memory element according to claim 1, wherein the resistively switchable material is doped with at least one of the following elements:

O, Si, H and N.

16. The resistive memory element according to claim 1, wherein the layer structure comprises several layers superimposed along a stacking direction z, and the resistively switchable material is laterally confined in a plane, perpendicular to said direction z, within the confining material.

19. A method of storing information in a resistive memory element having a layer structure as defined in claim 1, the method comprising:

applying an electric signal between the two conductive electrodes of said memory element to change a resistance state of the memory element.

17. A resistive memory device comprising one or more memory elements, each of at least a subset of the one or more memory elements having a layer structure, the layer structure comprising:

two layers forming two electrically conductive electrodes, respectively;

a resistively switchable material, sandwiched between the two layers forming the two electrodes, and in electrical connection therewith; and

a confining material, the resistively switchable material laterally confined within the confining material,

wherein;

the confining material

is sufficiently electrically insulating for an electric signal applied between the two conductive electrodes to change a resistance state of the memory element, in operation; and

has a thermal conductivity greater than 0.5 W/(m·

K), and

the resistively switchable material is an amorphous compound comprising carbon, which has a maximal lateral dimension, along a direction parallel to an average plane of the two layers forming the two electrodes, that is less than 60 nm.

18. The resistive memory device according to claim 17, wherein the memory device is configured as a resistive random access memory element.