# US 2021/0242082 A1 · Interconnect structures with cobalt-infused ruthenium liner and a cobalt cap

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- Number: US 2021/0242082 A1
- Document ID: US20210242082A1
- Status: Published application
- Kind: A1
- Application number: 16/781,038
- Filed: 2020-02-04
- Published: 2021-08-05
- Earliest claimed: 2020-02-04
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Joseph F. Maniscalco; Koichi Motoyama; Oscar van der Straten; Scott A. DeVries; Alexander Reznicek
- Web page: https://patentgrep.com/patent/US20210242082A1

## CPC

- H10W 20/035: {combinations of barrier, adhesion or liner layers, e.g. multi-layered barrier layers}
- H10W 20/034: {bottomless barrier, adhesion or liner layers}
- H10W 20/037: {the barrier, adhesion or liner layers being on top of a main fill metal}
- H10W 20/049: {by diffusing alloying elements}
- H10W 20/056: {by filling conductive material into holes, grooves or trenches}
- H10W 20/062: {by smoothing of conductive parts, e.g. by planarisation}
- H10W 20/081: {by forming openings in the dielectric parts}
- H10W 20/425: {Barrier, adhesion or liner layers}
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

An interconnect structure, and a method for forming the same includes forming recess within a dielectric layer and conformally depositing a barrier layer within the recess. A cobalt-infused ruthenium liner is formed above the barrier layer, the cobalt containing ruthenium liner formed by stacking a second liner above a first liner, the first liner positioned above the barrier layer. The first liner includes ruthenium while the second liner includes cobalt. Cobalt atoms migrate from the second liner to the first liner forming the cobalt-infused ruthenium liner. A conductive material is deposited above the cobalt-infused ruthenium liner to fill the recess followed by a capping layer made of cobalt.

## Claims

### Claim 1

A method of forming an interconnect structure, comprising:
forming a recess within a dielectric layer;
conformally depositing a barrier layer within the recess;
forming a cobalt-infused ruthenium liner above the barrier layer, the cobalt containing ruthenium liner comprising:
a first liner above the barrier layer, the first liner comprising ruthenium; and
a second liner above the first liner, the second liner comprising cobalt, wherein migration of cobalt atoms from the second liner to the first liner form the cobalt-infused ruthenium liner;
depositing a conductive material above the cobalt-infused ruthenium liner to fill the recess; and
forming a capping layer above a top surface of the conductive material, the capping layer comprising cobalt.

### Claim 2 (depends on 1)

The method of claim 1, wherein forming the cobalt-infused ruthenium liner reduces a concentration gradient between the capping layer and the cobalt-infused ruthenium liner preventing diffusion of cobalt atoms from the capping layer.

### Claim 3 (depends on 1)

The method of claim 1, wherein a thickness of the second liner is less than a thickness of the first liner.

### Claim 4 (depends on 3)

The method of claim 3, wherein the thickness of the second liner is greater than the thickness of the first liner.

### Claim 5 (depends on 1)

The method of claim 1, wherein the conductive material comprises copper.

### Claim 6 (depends on 1)

The method of claim 1, wherein the barrier layer comprises tantalum nitride.

### Claim 7 (depends on 1)

The method of claim 1, further comprising:
conducting a planarization process to remove excess conductive material from the interconnect structure.

### Claim 8

A method of forming an interconnect structure, comprising:
forming a recess within a dielectric layer;
conformally depositing a barrier layer within the recess;
conformally depositing a first liner above the barrier layer, the first liner comprising ruthenium;
conformally depositing a second liner above the first liner, the second liner comprising cobalt;
conformally depositing a third liner above the second liner, the third liner comprising ruthenium, wherein migration of cobalt atoms from the second liner to the first liner and the third liner form a cobalt-infused ruthenium liner;
depositing a conductive material above the cobalt-infused ruthenium liner to fill the recess; and
forming a capping layer above a top surface of the conductive material, the capping layer comprising cobalt.

### Claim 9 (depends on 8)

The method of claim 8, wherein forming the cobalt-infused ruthenium liner reduces a cobalt concentration between the cobalt-infused ruthenium liner and the capping layer that prevents diffusion of cobalt atoms from the capping layer.

### Claim 10 (depends on 8)

The method of claim 8, wherein a thickness of the second liner is less than a thickness of the first liner and the third liner.

### Claim 11 (depends on 8)

The method of claim 8, wherein the conductive material comprises copper.

### Claim 12 (depends on 8)

The method of claim 8, wherein the barrier layer comprises tantalum nitride.

### Claim 13 (depends on 8)

The method of claim 8, further comprising:
selectively removing portions of the first liner, portions of the second liner, and portions of the third liner parallel to the dielectric layer from a bottom region of the interconnect structure, wherein remaining portions of the first liner, the second liner, and the third liner remain on sidewalls of the interconnect structure.

### Claim 14 (depends on 13)

The method of claim 13, wherein selectively removing the portions of the first liner, the portions of the second liner, and the portions of the third liner parallel to the dielectric layer from the bottom region of the interconnect structure reduces via resistance.

### Claim 15 (depends on 8)

The method of claim 8, further comprising:
conducting a planarization process to remove excess conductive material from the interconnect structure.

### Claim 16

A semiconductor structure, comprising:
an interconnect structure within a dielectric layer, the interconnect structure comprising:
a barrier layer located on a bottom surface and sidewalls of the interconnect structure;
a first liner directly above the barrier layer, the first liner comprises ruthenium;
a second liner directly above the first liner, the second liner comprises cobalt;
a conductive material above the second liner substantially filling the interconnect structure; and
a capping layer directly above the conductive material, the capping layer comprises cobalt, wherein migration of cobalt atoms from the second liner to the first liner reduces a concentration gradient between the capping layer and the first liner that prevents diffusion of cobalt atoms from the capping layer.

### Claim 17 (depends on 16)

The semiconductor structure of claim 16, further comprises:
a third liner above the second liner, the third liner comprising ruthenium, wherein migration of cobalt atoms from the second liner interposed between the first liner and the third liner form a cobalt-infused ruthenium liner that reduces the concentration gradient between the capping layer and the cobalt-infused ruthenium liner and prevents diffusion of cobalt atoms from the capping layer.

### Claim 18 (depends on 17)

The semiconductor structure of claim 17, wherein portions of the first liner, portions of the second liner, and portions of the third liner remain on sidewalls of the interconnect structure and a bottom portion of the interconnect structure is covered only by the barrier layer.

### Claim 19 (depends on 18)

The semiconductor structure of claim 18, wherein a thickness of the second liner is less than a thickness of the first liner and the third liner.

### Claim 20 (depends on 16)

The semiconductor structure of claim 16, wherein the conductive material comprises copper and the barrier layer comprises tantalum nitride.