# US 10,770,359 B2 · Semiconductor device and method

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- Number: US 10,770,359 B2
- Document ID: US10770359B2
- Status: Granted
- Kind: B2
- Application number: 16/390,681
- Filed: 2019-04-22
- Published: 2019-12-05
- Granted: 2020-09-08
- Earliest claimed: 2018-05-30
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Company, Ltd.
- Inventors: Yi-Jing Lee; Tsung-Hsi Yang; Ming-Hua Yu
- Web page: https://patentgrep.com/patent/US10770359B2

## CPC

- H10D 84/017: {Manufacturing their source or drain regions, e.g. silicided source or drain regions}
- H10D 30/024: {of fin field-effect transistors [FinFET]}
- H10D 84/0193: {the components including FinFETs}
- H10D 84/038: {using silicon technology, e.g. SiGe}
- H10D 84/853: {comprising FinFETs}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

An embodiment is a device including a first fin extending from a substrate, a first gate stack over and along sidewalls of the first fin, a first gate spacer disposed along a sidewall of the first gate stack, and a first epitaxial source/drain region in the first fin and adjacent the first gate spacer. The first epitaxial source/drain region including a first epitaxial layer on the first fin, the first epitaxial layer including silicon and carbon, a second epitaxial layer on the first epitaxial layer, the second epitaxial layer having a different material composition than the first epitaxial layer, the first epitaxial layer separating the second epitaxial layer from the first fin, and a third epitaxial layer on the second epitaxial layer, the third epitaxial layer having a different material composition than the first epitaxial layer.

## Claims

### Claim 1

A device comprising:
a first fin extending from a substrate;
a first gate stack over and along sidewalls of the first fin;
a first gate spacer disposed along a sidewall of the first gate stack; and
a first epitaxial source/drain region in the first fin and adjacent the first gate spacer, the first epitaxial source/drain region comprising:
a first epitaxial layer on the first fin, the first epitaxial layer comprising silicon and carbon;
a second epitaxial layer on the first epitaxial layer, the second epitaxial layer having a different material composition than the first epitaxial layer, the first epitaxial layer separating the second epitaxial layer from the first fin; and
a third epitaxial layer on the second epitaxial layer, the third epitaxial layer having a different material composition than the first epitaxial layer and the second epitaxial layer.

### Claim 2 (depends on 1)

The device of claim 1, wherein the first epitaxial layer has a uniform thickness at sides and a bottom of the first epitaxial source/drain region.

### Claim 3 (depends on 1)

The device of claim 1, wherein the first epitaxial layer is thicker at a bottom than at sides of the first epitaxial source/drain region.

### Claim 4 (depends on 1)

The device of claim 1, wherein the first epitaxial layer has an atomic concentration of carbon in a range from 0.2% to 5%.

### Claim 5 (depends on 1)

The device of claim 1, wherein the second epitaxial layer has a faceted top surface, and wherein the third epitaxial layer has a uniform thickness across the faceted top surface of the second epitaxial layer.

### Claim 6 (depends on 1)

The device of claim 1, wherein the third epitaxial layer contacts the first epitaxial layer and the first gate spacer.

### Claim 7 (depends on 1)

The device of claim 1, further comprising:
a second fin extending from the substrate;
a second gate stack over and along sidewalls of the second fin;
a second gate spacer disposed along a sidewall of the second gate stack; and
a second epitaxial source/drain region in the second fin and adjacent the second gate spacer, the second epitaxial source/drain region having a different material composition than the first epitaxial source/drain region.

### Claim 8 (depends on 1)

The device of claim 1, wherein the first epitaxial source/drain region extends under the first gate spacer.

### Claim 9

A device comprising:
a fin extending upwards from a substrate;
a gate electrode over the fin; and
an epitaxial source/drain region in the fin, the epitaxial source/drain region comprising:
a first epitaxial region on the fin, the first epitaxial region comprising silicon and carbon;
a second epitaxial region on the first epitaxial region, wherein the second epitaxial region has a different material composition than the first epitaxial region, and wherein the first epitaxial region is interposed between the second epitaxial region and the fin; and
a third epitaxial region on the second epitaxial region, wherein the third epitaxial region has a different material composition than both the first epitaxial region and the second epitaxial region.

### Claim 10 (depends on 9)

The device of claim 9, wherein a ratio of a first thickness of a first sidewall of the first epitaxial region to a second thickness of a bottom of the first epitaxial region is from 0.3 to 1.3.

### Claim 11 (depends on 10)

The device of claim 10, wherein the first thickness is from 3 nm to 12 nm.

### Claim 12 (depends on 10)

The device of claim 10, wherein the second thickness is from 3 nm to 12 nm.

### Claim 13 (depends on 9)

The device of claim 9, wherein the first epitaxial region further comprises phosphorous.

### Claim 14 (depends on 9)

The device of claim 9, wherein the first epitaxial region has an atomic concentration of carbon from 0.2% to 5%.

### Claim 15

A device comprising:
a semiconductor fin;
a gate stack extending on a top surface and sidewalls of the semiconductor fin;
a gate spacer extending on a sidewall of the gate stack; and
a source/drain region in the semiconductor fin and adjacent the gate spacer, the source/drain region comprising:
a first source/drain region on the semiconductor fin;
a second source/drain region on the first source/drain region, the first source/drain region separating the second source/drain region from the semiconductor fin; and
a third source/drain region on the second source/drain region, the first source/drain region having a greater concentration of carbon than the second source/drain region and the third source/drain region.

### Claim 16 (depends on 15)

The device of claim 15, wherein the semiconductor fin extends from a semiconductor substrate, wherein the first source/drain region extends below the gate spacer in a direction perpendicular with a major surface of the semiconductor substrate.

### Claim 17 (depends on 16)

The device of claim 16, wherein the first source/drain region extends laterally a distance from 0.3 nm to 5 nm under outer sidewalls of the gate spacer.

### Claim 18 (depends on 15)

The device of claim 15, further comprising a source/drain contact, the source/drain contact contacting an uppermost surface of the third source/drain region.

### Claim 19 (depends on 15)

The device of claim 15, wherein the third source/drain region has a greater concentration of phosphorous, boron, or germanium dopants than the second source/drain region.

### Claim 20 (depends on 15)

The device of claim 15, wherein the second source/drain region has a greater concentration of phosphorous, boron, or germanium dopants than the third source/drain region.