# US 10,483,161 B2 · Multi-barrier deposition for air gap formation

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- Number: US 10,483,161 B2
- Document ID: US10483161B2
- Status: Granted
- Kind: B2
- Application number: 16/222,015
- Filed: 2018-12-17
- Published: 2019-05-09
- Granted: 2019-11-19
- Earliest claimed: 2015-11-16
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Company, Ltd.
- Inventors: Hsiang-Wei Lin
- Web page: https://patentgrep.com/patent/US10483161B2

## CPC

- H10W 20/46: comprising air gaps
- H10D 62/115: {Dielectric isolations, e.g. air gaps}
- H10W 20/072: {of dielectric parts comprising air gaps}
- H10W 20/075: {of multilayered thin functional dielectric layers}
- H10W 20/077: {on sidewalls or on top surfaces of conductors (H10W20/076 takes precedence)}
- H10W 20/081: {by forming openings in the dielectric parts}
- H10W 20/42: Vias, e.g. via plugs
- 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: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A method includes forming a first conductive line and a second conductive line in a dielectric layer, etching a portion of the dielectric layer to form a trench between the first conductive line and the second conductive line, and forming a first etch stop layer. The first etch stop layer extends into the trench. A second etch stop layer is formed over the first etch stop layer. The second etch stop layer extends into the trench, and the second etch stop layer is more conformal than the first etch stop layer. A dielectric material is filled into the trench and over the second etch stop layer. An air gap is formed in the dielectric material.

## Claims

### Claim 1

An integrated circuit structure comprising:
a dielectric layer;
a first conductive line and a second conductive line in the dielectric layer;
a trench in the dielectric layer, the trench extending between the first conductive line and the second conductive line;
a first etch stop layer having a first portion with a first thickness extending over the dielectric layer, and a second portion with a second thickness, less than the first thickness, extending along sidewalls of the trench;
a second etch stop layer contacting the first etch stop layer, the second etch stop layer having a third portion with a third thickness extending over the first portion and having a fourth portion with a fourth thickness over the second portion, wherein a first ratio of the fourth thickness to the third thickness is greater than a second ratio of the second thickness to the first thickness;
a dielectric material in the trench and contacting the second etch stop layer; and
an air gap in the dielectric material and in the trench.

### Claim 2 (depends on 1)

The integrated circuit structure of claim 1, wherein the first etch stop layer further includes an overhang region at a junction between the first portion and the second portion, the overhang region having a thickness that is greater than the first, second, third and fourth thickness.

### Claim 3 (depends on 2)

The integrated circuit structure of claim 2, wherein the overhang region has a thickness of greater than about 50 Å.

### Claim 4 (depends on 1)

The integrated circuit structure of claim 1, wherein the second etch stop layer is substantially conformal to the first etch stop layer.

### Claim 5 (depends on 1)

The integrated circuit structure of claim 1, wherein at least one of the first conductive line and the second conductive line has a first corner proximate the trench and a second corner distal to the trench and wherein the first corner has a cross-sectional profile that is rounded relative to a cross-sectional profile of the second corner.

### Claim 6 (depends on 1)

The integrated circuit structure of claim 1, wherein the air gap has a topmost portion, the topmost portion being higher than a topmost surface of the first conductive line.

### Claim 7 (depends on 1)

The integrated circuit structure of claim 1, wherein the topmost portion of the air gap is lower than a topmost surface of the second etch stop layer.

### Claim 8 (depends on 1)

The integrated circuit structure of claim 1, wherein each of the first etch stop layer and the second etch stop layer has a first thickness measured at a position aligned to a middle line between opposite edges of the first conductive line, and a second thickness measured at a middle height of the first conductive line, and a ratio of the second thickness to the first thickness of the first etch stop layer is smaller than 60 percent, and a ratio of the second thickness to the first thickness of the second etch stop layer is greater than 60 percent.

### Claim 9 (depends on 1)

The integrated circuit structure of claim 1, wherein the first etch stop layer and the second etch stop layer are formed of a same dielectric material.

### Claim 10 (depends on 1)

The integrated circuit structure of claim 1, further comprising a gap in the first etch stop layer and the second etch stop layer and a conductive contact plug extending through the gap and contacting the first conductive line.

### Claim 11 (depends on 1)

The integrated circuit structure of claim 1, further comprising a third etch stop layer between the first portion of the first etch stop layer and the first conductive line.

### Claim 12

An integrated circuit structure comprising:
a substrate;
a plurality integrated circuit devices formed on or in the substrate;
a first connection layer over the substrate, the first connection layer including:
a first dielectric layer, and
a first plurality of metal lines; and
a second connection layer over the first connection layer, the second connection layer including:
a second dielectric layer,
a second metal line,
a trench in the second dielectric layer, the trench being adjacent the second metal line,
a first etch stop layer extending substantially non-conformally over a first surfaced defined by the second dielectric layer, the second metal line and sidewalls and a bottom of the trench,
a second etch stop layer contacting and extending substantially conformally over a surface defined by the first etch stop layer, and
a dielectric material contacting and extending over the second etch stop layer into the trench, the dielectric material including an air gap within the trench.

### Claim 13 (depends on 12)

The integrated circuit structure of claim 12, wherein the first etch stop layer includes an overhang extending from a top region of a sidewall of the trench and extends into the trench.

### Claim 14 (depends on 12)

The integrated circuit structure of claim 12, further including a third etch stop layer overlying a portion of the second metal line and underlying the first etch stop layer, wherein the third etch stop layer is formed of a same dielectric material as the first etch stop layer.

### Claim 15 (depends on 12)

The integrated circuit structure of claim 12, wherein the air gap has a topmost portion, the topmost portion being higher than a topmost surface of the second metal line.

### Claim 16 (depends on 15)

The integrated circuit structure of claim 15, wherein the topmost portion of the air gap is lower than a topmost surface of the second etch stop layer.

### Claim 17 (depends on 12)

The integrated circuit structure of claim 12, further comprising a third connection layer at least partially embedded within the dielectric material.

### Claim 18

A method comprising:
forming a conductive line in a dielectric layer;
etching portions of the dielectric layer to form a first trench on a first side of the conductive line and a second trench on a second side of the conductive line;
forming a first etch stop layer, wherein the first etch stop layer extends substantially non-conformally into the first trench and the second trench;
forming a second etch stop layer over the first etch stop layer, wherein the second etch stop layer extends substantially conformally into the first trench and the second trench; and
filling a dielectric material into the first trench and the second trench.

### Claim 19 (depends on 18)

The method of claim 18, wherein the step of filling a dielectric material into the first trench and the second trench includes forming respective airgaps surrounded by the dielectric material within the first trench and the second trench.

### Claim 20 (depends on 18)

The method of claim 18, wherein the forming the first etch stop layer and the forming the second etch stop layer are performed using same process gases with same flow rates, with no vacuum break therebetween.