# US 10,770,346 B2 · Selective cobalt removal for bottom up gapfill

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- Number: US 10,770,346 B2
- Document ID: US10770346B2
- Status: Granted
- Kind: B2
- Application number: 16/229,710
- Filed: 2018-12-21
- Published: 2019-04-25
- Granted: 2020-09-08
- Earliest claimed: 2016-11-11
- Assignees: Applied Materials, Inc.
- Applicants: Applied Materials, Inc.
- Inventors: Xikun Wang; Jianxin Lei; Nitin Ingle; Roey Shaviv
- Web page: https://patentgrep.com/patent/US10770346B2

## CPC

- H10W 20/056: {by filling conductive material into holes, grooves or trenches}
- H10P 50/266: {by vapour etching only}
- H10P 50/267: {using plasmas}
- H10P 72/0421: {for drying etching}
- H10P 95/00: Generic processes or apparatus for manufacture or treatments not covered by the other groups of this subclass
- H10W 20/4403: {based on metals, e.g. alloys, metal silicides (H10W20/4484 takes precedence)}
- H10W 20/4437: {the principal metal being a transition metal}
- 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

Exemplary methods for removing cobalt material may include flowing a chlorine-containing precursor into a processing region of a semiconductor processing chamber. The methods may include forming a plasma of the chlorine-containing precursor to produce plasma effluents. The methods may also include contacting an exposed region of cobalt with the plasma effluents. The exposed region of cobalt may include an overhang of cobalt on a trench defined on a substrate. The plasma effluents may produce cobalt chloride at the overhang of cobalt. The methods may include flowing a nitrogen-containing precursor into the processing region of the semiconductor processing chamber. The methods may further include contacting the cobalt chloride with the nitrogen-containing precursor. The methods may also include recessing the overhang of cobalt.

## Claims

### Claim 1

An etching method comprising:
flowing a chlorine-containing precursor into a processing region of a semiconductor processing chamber;
forming a plasma of the chlorine-containing precursor to produce plasma effluents;
contacting an exposed region of cobalt with the plasma effluents, wherein the plasma effluents produce cobalt chloride at the exposed region of cobalt to a modification depth of at least about 5 Å;
flowing a nitrogen-containing precursor into the processing region of the semiconductor processing chamber;
contacting the cobalt chloride with the nitrogen-containing precursor;
recessing the exposed region of cobalt to at least the modification depth, and
removing residue from exposed cobalt surfaces.

### Claim 2 (depends on 1)

The etching method of claim 1, wherein a plasma power of the plasma formed from the chlorine-containing precursor is less than about 100 W.

### Claim 3 (depends on 1)

The etching method of claim 1, wherein a temperature of the substrate is maintained between about 175° C. and about 250° C. during the etching method.

### Claim 4 (depends on 1)

The etching method of claim 1, wherein a pressure within the semiconductor processing chamber is maintained below about 5 Torr.

### Claim 5 (depends on 1)

The etching method of claim 1, wherein the etching method removes at least about 10 Å of cobalt.

### Claim 6 (depends on 1)

The etching method of claim 1, further comprising depositing additional cobalt in the trench, and producing an overhang of cobalt.

### Claim 7 (depends on 1)

The etching method of claim 1, wherein the etching method is repeated for at least two cycles.

### Claim 8 (depends on 7)

The etching method of claim 7, wherein a total removal of cobalt after the at least 2 cycles is at least about 20 Å.

### Claim 9 (depends on 1)

The etching method of claim 1, wherein removing residue comprises contacting the substrate with effluents of a hydrogen-containing plasma.

### Claim 10 (depends on 1)

The etching method of claim 1, wherein the method removes less than 5% of material proximate a bottom region of the trench.

### Claim 11 (depends on 1)

The etching method of claim 1, wherein the etching method has a selectivity of cobalt to titanium nitride greater than or about 50:1.

### Claim 12 (depends on 1)

The etching method of claim 1, wherein the etching method has a selectivity of cobalt to silicon nitride and silicon oxide greater than or about 100:1:1.

### Claim 13 (depends on 1)

The etching method of claim 1, wherein the processing region is maintained plasma-free while contacting the cobalt chloride with the nitrogen-containing precursor.

### Claim 14

A method of producing a gap-free cobalt fill, the method comprising:
depositing a first amount of cobalt into a trench defined on a substrate;
flowing a chlorine-containing precursor into a processing region of a semiconductor processing chamber, wherein the processing region houses the substrate;
forming a plasma of the chlorine-containing precursor to produce plasma effluents;
contacting a region of the cobalt proximate an entrance to the trench with the plasma effluents to produce cobalt chloride to a modification depth of at least about 5 Å;
flowing a nitrogen-containing precursor into the processing region of the semiconductor processing chamber;
contacting the cobalt chloride with the nitrogen-containing precursor;
recessing the cobalt proximate the entrance to the trench to at least the modification depth, and
removing residue from exposed cobalt surfaces.

### Claim 15 (depends on 14)

The method of producing a gap-free cobalt fill of claim 14, further comprising depositing a second amount of cobalt into the trench, wherein the deposition forms an overhang of cobalt at the opening of the trench.

### Claim 16 (depends on 14)

The method of producing a gap-free cobalt fill of claim 14, wherein the method is repeated at least twice.

### Claim 17 (depends on 14)

The method of producing a gap-free cobalt fill of claim 14, wherein the cobalt is at least 80% maintained in the trench while recessing the cobalt proximate the entrance to the trench.

### Claim 18 (depends on 14)

The method of producing a gap-free cobalt fill of claim 14, wherein a plasma power of the plasma formed from the chlorine-containing precursor is less than or about 60 W, wherein the flow rate of the chlorine-containing precursor is below or about 30 sccm, and wherein the chlorine-containing precursor is flowed into the processing region for a time period of less than or about 20 seconds.

### Claim 19 (depends on 14)

The method of producing a gap-free cobalt fill of claim 14, wherein removing residue comprises contacting the substrate with effluents of a hydrogen-containing plasma.

### Claim 20 (depends on 14)

The method of producing a gap-free cobalt fill of claim 14, wherein the cobalt is deposited on a metallic nitride liner formed within the trench.