# US 12,183,626 B2 · Metal interconnect structure having cap layer with different thicknesses and method for fabricating the same

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- Number: US 12,183,626 B2
- Document ID: US12183626B2
- Status: Granted
- Kind: B2
- Application number: 17/883,647
- Filed: 2022-08-09
- Published: 2022-12-01
- Granted: 2024-12-31
- Earliest claimed: 2018-08-16
- Assignees: United Microelectronics Corp.
- Applicants: United Microelectronics Corp.
- Inventors: Yi-How Chou; Tzu-Hao Fu; Tsung-Yin Hsieh; Chih-Sheng Chang; Shih-Chun Tsai; Kun-Chen Ho; Yang-Chou Lin
- Web page: https://patentgrep.com/patent/US12183626B2

## CPC

- H10W 20/081: {by forming openings in the dielectric parts}
- H10P 70/234: {the processing being the formation of vias or contact holes}
- H10W 20/033: {in openings in dielectrics}
- H10W 20/037: {the barrier, adhesion or liner layers being on top of a main fill metal}
- H10W 20/071: {of dielectric parts thereof}
- H10W 20/083: {the openings being via holes penetrating underlying conductors}
- H10W 20/088: {involving partial etching of via holes}
- H10W 20/096: {by contacting with gases, liquids or plasmas}
- H10W 20/42: Vias, e.g. via plugs
- H10W 20/425: {Barrier, adhesion or liner layers}
- H10W 20/072: {of dielectric parts comprising air gaps}
- H10W 20/46: comprising air gaps
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A metal interconnect structure includes a first metal interconnection in an inter-metal dielectric (IMD) layer on a substrate, a second metal interconnection on the first metal interconnection, and a cap layer between the first metal interconnection and the second metal interconnection. Preferably, a top surface of the first metal interconnection is even with a top surface of the IMD layer and the cap layer is made of conductive material.

## Claims

### Claim 1

A metal interconnect structure, comprising:
a first metal interconnection in an inter-metal dielectric (IMD) layer on a substrate, wherein a top surface of the first metal interconnection is even with a top surface of the IMD layer;
a second metal interconnection on the first metal interconnection;
a cap layer between and directly contacting the first metal interconnection and the second metal interconnection, wherein the cap layer comprises conductive material; and
an air gap in the cap layer.

### Claim 2 (depends on 1)

The metal interconnect structure of claim 1, wherein the cap layer comprises a first thickness between the first metal interconnection and the second metal interconnection and a second thickness adjacent to two sides of the first thickness.

### Claim 3 (depends on 2)

The metal interconnect structure of claim 2, wherein the second thickness is greater than the first thickness.

### Claim 4 (depends on 2)

The metal interconnect structure of claim 2, wherein the cap layer comprises a third thickness adjacent to two sides of the second thickness.

### Claim 5 (depends on 4)

The metal interconnect structure of claim 4, wherein the third thickness is greater than the second thickness.

### Claim 6 (depends on 1)

The metal interconnect structure of claim 1, wherein the second metal interconnection comprises:
a barrier layer contacting the cap layer;
a liner on the barrier layer; and
a metal layer on the liner.

### Claim 7 (depends on 6)

The metal interconnect structure of claim 6, wherein the barrier layer and the liner are U-shaped.

### Claim 8 (depends on 6)

The metal interconnect structure of claim 6, wherein the cap layer and the liner comprise same material.

### Claim 9 (depends on 6)

The metal interconnect structure of claim 6, wherein the cap layer and the liner comprise cobalt (Co).