# US 7,071,091 B2 · Method of forming air gaps in a dielectric material using a sacrificial film

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- Number: US 7,071,091 B2
- Document ID: US7071091B2
- Status: Granted
- Kind: B2
- Application number: 10/828,885
- Filed: 2004-04-20
- Published: 2005-10-20
- Granted: 2006-07-04
- Earliest claimed: 2004-04-20
- Assignees: Intel Corporation
- Inventors: James S. Clarke; Michael D. Goodner
- Web page: https://patentgrep.com/patent/US7071091B2

## CPC

- H10W 20/46: comprising air gaps
- H10W 20/072: {of dielectric parts comprising air gaps}
- H10W 20/47: comprising two or more dielectric layers having different properties, e.g. different dielectric constants
- H10W 20/495: {Capacitive arrangements or effects of, or between wiring layers}
- H10W 20/0765: {the thin functional dielectric layers being temporary, e.g. sacrificial layers}
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A method of forming air gaps surrounding conductors in a dielectric layer, the dielectric layer comprising, for example, part of the interconnect structure of an integrated circuit device. The air gaps are formed, in part, by depositing a sacrificial material within a trench and/or via that have been formed in a dielectric layer, and the sacrificial material is ultimately removed after metal deposition to create the air gaps. A porous dielectric cap may be deposited over the dielectric layer, and the sacrificial material may be removed through this porous dielectric layer. Other embodiments are described and claimed.

## Claims

### Claim 1

A method comprising:
forming a trench and a via in a layer of dielectric material, the via having one end opening into the trench and an opposing end extending down to a conductor in an underlying layer;
selectively depositing a layer of a sacrificial material over the dielectric material layer and over surfaces of the trench and via;
depositing a layer of a conductive material over the sacrificial material layer and the conductor in the underlying layer;
removing excess conductive material and excess sacrificial material from an upper surface of the dielectric material layer;
depositing a layer of a porous dielectric material over the upper surface of the dielectric material layer and exposed portions of the conductive and sacrificial material layers; and
removing the sacrificial material to form air gaps surrounding the conductive material within the trench and the via.

### Claim 2 (depends on 1)

The method of claim 1, wherein the sacrificial material layer comprises a polymer material.

### Claim 3 (depends on 2)

The method of claim 2, wherein the sacrificial material layer is deposited using a chemical growth process.

### Claim 4 (depends on 2)

The method of claim 2, wherein the sacrificial material layer is deposited using a photo induced-free radical polymerization process.

### 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 excess conductive and sacrificial materials are removed from the upper surface of the dielectric material layer using a chemical-mechanical polishing (CMP) process.

### Claim 7 (depends on 1)

The method of claim 1, wherein the porous dielectric material comprises a silica based material, a silicon nitride based material, a silicon carbide based material, an amorphous carbon based material, or an organic film.

### Claim 8 (depends on 1)

The method of claim 1, wherein removing the sacrificial material comprises:
thermally decomposing the sacrificial material layer into one or more residue materials; and
performing a rinse process to remove the residue materials through the porous dielectric layer.

### Claim 9 (depends on 8)

The method of claim 8, wherein thermal decomposition is performed at a temperature up to approximately 450° C.

### Claim 10 (depends on 8)

The method of claim 8, wherein the rinse process is performed using a supercritical CO2 agent.

### Claim 11 (depends on 1)

The method of claim 1, wherein the air gaps each have a thickness of between 5 nm and 15 nm.

### Claim 12 (depends on 1)

The method of claim 1, wherein the underlying layer comprises another layer of dielectric material.

### Claim 13 (depends on 1)

The method of claim 1, wherein the underlying layer comprises a semiconductor wafer.

### Claim 14

A method comprising:
forming a trench and a via in a layer of dielectric material, the via having one end opening into the trench and an opposing end extending down to a conductor in an underlying layer;
depositing a layer of a sacrificial material over the dielectric material layer and over surfaces of the trench and via;
etching the sacrificial material layer to remove at least a portion of the sacrificial material layer overlying the conductor in the underlying layer;
depositing a layer of a conductive material over the sacrificial material layer and the conductor in the underlying layer;
removing excess conductive material and excess sacrificial material from an upper surface of the dielectric material layer;
depositing a layer of a porous dielectric material over the upper surface of the dielectric material layer and exposed portions of the conductive and sacrificial material layers; and
removing the sacrificial material to form air gaps surrounding the conductive material within the trench and the via.

### Claim 15 (depends on 14)

The method of claim 14, wherein the sacrificial material layer comprises a polymer material.

### Claim 16 (depends on 14)

The method of claim 14, wherein the conductive material comprises copper.

### Claim 17 (depends on 14)

The method of claim 14, wherein the porous dielectric material comprises a silica based material, a silicon nitride based material, a silicon carbide based material, an amorphous carbon based material, or an organic film.

### Claim 18 (depends on 14)

The method of claim 14, wherein removing the sacrificial material comprises:
thermally decomposing the sacrificial material layer into one or more residue materials; and
performing a rinse process to remove the residue materials through the porous dielectric layer.

### Claim 19 (depends on 14)

The method of claim 14, etching the sacrificial material layer to remove at least a portion of the sacrificial material layer overlying the conductor in the underlying layer comprises performing an anisotropic etch process.