# US 2021/0280465 A1 · Structurally Stable Self-Aligned Subtractive Vias

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- Number: US 2021/0280465 A1
- Document ID: US20210280465A1
- Status: Published application
- Kind: A1
- Application number: 16/813,682
- Filed: 2020-03-09
- Published: 2021-09-09
- Earliest claimed: 2020-03-09
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Sagarika Mukesh; Dominik METZLER; CHANRO PARK; Timothy Mathew Philip
- Web page: https://patentgrep.com/patent/US20210280465A1

## CPC

- H10W 20/069: {by forming self-aligned vias or self-aligned contact plugs}
- H10P 50/71: {using masks for conductive or resistive materials}
- H10W 20/063: {by forming conductive members before forming protective insulating material}
- H10W 20/0633: {using subtractive patterning of the conductive members}
- H10W 20/0693: {by forming self-aligned vias}
- H10W 20/42: Vias, e.g. via plugs
- 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

Techniques for forming self-aligned subtractive top vias using a via hardmask supported by scaffolding are provided. In one aspect, a method of forming top vias includes: forming metal lines on a substrate using line hardmasks; patterning vias in the line hardmasks; filling the vias and trenches in between the metal lines with a via hardmask material to form via hardmasks and a scaffolding adjacent to and supporting the via hardmasks; removing the line hardmasks; and recessing the metal lines using the via hardmasks to form the top vias that are self-aligned with the metal lines. The scaffolding can also be placed prior to patterning of the vias in the line hardmasks. A structure formed in accordance with the present techniques containing top vias is also provided.

## Claims

### Claim 1

A method of forming top vias, the method comprising the steps of:
forming metal lines on a substrate using line hardmasks;
patterning vias in the line hardmasks;
filling the vias and trenches in between the metal lines with a via hardmask material, wherein the via hardmask material filling the vias comprises via hardmasks, and wherein the via hardmask material filling the trenches in between the metal lines comprises a scaffolding adjacent to and supporting the via hardmasks;
removing the line hardmasks; and
recessing the metal lines using the via hardmasks to form the top vias that are self-aligned with the metal lines.

### Claim 2 (depends on 1)

The method of claim 1, further comprising the step of:
removing the via hardmasks and the scaffolding.

### Claim 3 (depends on 1)

The method of claim 1, wherein the metal lines comprise a metal selected from the group consisting of: cobalt (Co), ruthenium (Ru), tungsten (W), and combinations thereof.

### Claim 4 (depends on 1)

The method of claim 1, wherein the line hardmasks comprise a material selected from the group consisting of: silicon nitride (SiN), silicon oxynitride (SiON), silicon carbide nitride (SiCN), silicon oxide (SiOx), and combinations thereof.

### Claim 5 (depends on 1)

The method of claim 1, further comprising the steps of:
depositing an organic planarizing layer (OPL) onto the line hardmasks and the metal lines, and filling the trenches in between the metal lines;
patterning the vias in the OPL and in the line hardmasks; and
removing the OPL.

### Claim 6 (depends on 1)

The method of claim 1, wherein the via hardmask material is selected from the group consisting of: SiOx, spin-on-glass, and combinations thereof.

### Claim 7 (depends on 1)

The method of claim 1, further comprising the steps of:
burying the metal lines in an interlayer dielectric (ILD); and
polishing the ILD to expose a top of the top vias.

### Claim 8 (depends on 1)

The method of claim 1, further comprising the steps of:
cutting at least one of the metal lines into segments with a line cut trench in between the segments; and
filling the vias, the trenches in between the metal lines, and the line cut trench with the via hardmask material.

### Claim 9 (depends on 8)

The method of claim 8, wherein at least one of the top vias is self-aligned with an end of at least one of the segments.

### Claim 10

A method of forming top vias, the method comprising the steps of:
forming metal lines on a substrate using line hardmasks;
filling trenches in between the metal lines with a via hardmask material;
patterning vias in the line hardmasks;
filling the vias with the via hardmask material, wherein the via hardmask material filling the vias comprises via hardmasks, and wherein the via hardmask material filling the trenches in between the metal lines comprises a scaffolding adjacent to and supporting the via hardmasks;
removing the line hardmasks; and
recessing the metal lines using the via hardmasks to form the top vias that are self-aligned with the metal lines.

### Claim 11 (depends on 10)

The method of claim 10, further comprising the step of:
removing the via hardmasks and the scaffolding.

### Claim 12 (depends on 10)

The method of claim 10, wherein the metal lines comprise a metal selected from the group consisting of: Co, Ru, W, and combinations thereof.

### Claim 13 (depends on 10)

The method of claim 10, wherein the line hardmasks comprise a material selected from the group consisting of: SiN, SiON, SiCN, SiOx, and combinations thereof.

### Claim 14 (depends on 10)

The method of claim 10, further comprising the steps of:
depositing an OPL onto the line hardmasks and the metal lines over the scaffolding;
patterning the vias in the OPL and in the line hardmasks; and
removing the OPL.

### Claim 15 (depends on 10)

The method of claim 10, wherein the via hardmask material is selected from the group consisting of: SiOx, spin-on-glass, and combinations thereof.

### Claim 16 (depends on 10)

The method of claim 10, further comprising the steps of:
burying the metal lines in an ILD; and
polishing the ILD to expose a top of the top vias.

### Claim 17 (depends on 10)

The method of claim 10, further comprising the steps of:
cutting at least one of the metal lines into segments with a line cut trench in between the segments; and
filling the vias, the trenches in between the metal lines, and the line cut trench with the via hardmask material.

### Claim 18

A structure, comprising:
metal lines formed on a substrate;
top vias self-aligned with the metal lines;
via hardmasks disposed on the top vias; and
a scaffolding, disposed in trenches between the metal lines, adjacent to and supporting the via hardmasks.

### Claim 19 (depends on 18)

The structure of claim 18, wherein via hardmasks and the scaffolding are formed from a via hardmask material selected from the group consisting of: SiOx, spin-on-glass, and combinations thereof.

### Claim 20 (depends on 18)

The structure of claim 18, further comprising:
an ILD surrounding the metal lines and the top vias.