# US 12,218,216 B2 · Method for manufacturing semiconductor devices having gate spacers with bottom portions recessed in a fin

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- Number: US 12,218,216 B2
- Document ID: US12218216B2
- Status: Granted
- Kind: B2
- Application number: 18/232,191
- Filed: 2023-08-09
- Published: 2023-11-30
- Granted: 2025-02-04
- Earliest claimed: 2020-07-22
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Company, Ltd.
- Inventors: Wei-Liang Lu; Chang-Yin Chen; Chih-Han Lin; Chia-Yang Liao
- Web page: https://patentgrep.com/patent/US12218216B2

## CPC

- H10D 64/671: {the conductor having lateral variation in doping or structure}
- H10D 30/024: {of fin field-effect transistors [FinFET]}
- H10D 30/62: Fin field-effect transistors [FinFET]
- H10D 30/6211: {having fin-shaped semiconductor bodies integral with the bulk semiconductor substrates}
- H10D 62/021: {Forming source or drain recesses by etching e.g. recessing by etching and then refilling}
- H10D 62/151: {of IGFETs (of IGFETs having LDD or DDD structure H10D30/601; of thin film transistors H10D30/6713)}
- H10D 64/015: {removing at least parts of gate spacers, e.g. disposable spacers}
- H10D 64/017: {using dummy gates in processes wherein at least parts of the final gates are self-aligned to the dummy gates, i.e. replacement gate processes}
- H10D 64/021: {using multiple gate spacer layers, e.g. bilayered sidewall spacers}
- H10D 84/0147: {Manufacturing their gate sidewall spacers}
- H10D 84/0158: {the components including FinFETs}
- H10D 84/0184: {Manufacturing their gate sidewall spacers}
- H10D 84/0193: {the components including FinFETs}
- H10D 84/038: {using silicon technology, e.g. SiGe}
- H10D 84/834: {comprising FinFETs}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A semiconductor device and methods of fabricating the same are disclosed. The semiconductor device includes a substrate, a fin structure with a fin top surface disposed on the substrate, a source/drain (S/D) region disposed on the fin structure, a gate structure disposed on the fin top surface, and a gate spacer with first and second spacer portions disposed between the gate structure and the S/D region. The first spacer portion extends above the fin top surface and is disposed along a sidewall of the gate structure. The second spacer portion extends below the fin top surface and is disposed along a sidewall of the S/D region.

## Claims

### Claim 1

A method, comprising:
forming a fin structure with a fin top surface on a substrate;
forming first and second polysilicon structures on the fin top surface;
forming a spacer opening in the fin structure and between the first and second polysilicon structures;
forming a gate spacer, wherein forming the gate spacer comprises:
forming a first spacer portion of the gate spacer along a sidewall of the first polysilicon structure, and
forming a second spacer portion of the gate spacer, in the spacer opening, comprising forming the second spacer portion with a triangular-shaped structure comprising a first sloped spacer sidewall facing the fin structure and a second sloped spacer sidewall facing the spacer opening;
forming a source/drain (S/D) region, between the first and second polysilicon structures, comprising forming the S/D region with a sloped sidewall adjacent to the second sloped spacer sidewall; and
replacing the first and second polysilicon structures with first and second gate structures.

### Claim 2 (depends on 1)

The method of claim 1, wherein forming the spacer opening comprises etching an exposed region of the fin structure between the first and second polysilicon structures.

### Claim 3 (depends on 1)

The method of claim 1, wherein forming the spacer opening comprises etching the fin structure with an etching gas of sulfur hexafluoride or carbon tetrafluoride in a gas mixture comprising chlorine, hydrogen bromide, and helium.

### Claim 4 (depends on 3)

The method of claim 3, wherein a ratio of the etching gas to the gas mixture is about 1:10 to about 1:25.

### Claim 5 (depends on 1)

The method of claim 1, wherein forming the gate spacer comprises depositing a spacer layer on the first and second polysilicon structures and in the spacer opening.

### Claim 6 (depends on 1)

The method of claim 1, wherein forming the S/D region comprises:
etching the fin structure through the spacer opening to form a S/D opening with substantially vertical sidewalls; and
epitaxially growing a semiconductor layer in the S/D opening.

### Claim 7 (depends on 1)

The method of claim 1, wherein forming the S/D region comprises forming a S/D opening extending below the second spacer portion; and
wherein entire sidewalls of the S/D opening are substantially vertical.

### Claim 8 (depends on 1)

The method of claim 1, wherein forming the S/D region comprises forming the S/D region with a S/D portion extending below the second spacer portion; and
wherein entire sidewalls of the S/D portion are substantially vertical.

### Claim 9 (depends on 1)

The method of claim 1, wherein forming the second spacer portion comprises forming the second spacer portion with the first sloped spacer sidewall in contact with a fin sidewall of the fin structure; and
wherein the first sloped spacer sidewall forms an angle of about 30 degrees to about 60 degrees with the fin top surface.

### Claim 10

A method, comprising:
forming first and second fin structures on a substrate;
forming first and second polysilicon structures on the first and second fin structures, respectively;
forming a first gate spacer comprising a first spacer portion along a sidewall of the first polysilicon structure and a second spacer portion along a fin sidewall of the first fin structure;
forming, at a same time as forming the first gate spacer, a second gate spacer comprising a third spacer portion along a sidewall of the second polysilicon structure and a fourth spacer portion along a fin sidewall of the second fin structure, wherein a height of the second spacer portion is greater than a height of the fourth spacer portion;
forming a first source/drain (S/D) region adjacent to the first gate spacer;
forming a second S/D region adjacent to the second gate spacer; and
replacing the first and second polysilicon structures with first and second gate structures.

### Claim 11 (depends on 10)

The method of claim 10, wherein forming the first gate spacer comprises forming a first spacer opening with a first radius of curvature; and
wherein forming the second gate spacer comprises forming a second spacer opening with a second radius of curvature smaller than the first radius of curvature.

### Claim 12 (depends on 10)

The method of claim 10, wherein forming the first gate spacer comprises forming the second spacer portion with a sloped sidewall in contact with the fin sidewall of the first fin structure.

### Claim 13 (depends on 10)

The method of claim 10, wherein forming the first gate spacer comprises forming the second spacer portion with a sidewall forming an angle of about 30 degrees to about 60 degrees with a top surface of the first fin structure.

### Claim 14 (depends on 10)

The method of claim 10, wherein forming the first S/D region comprises forming a first S/D opening extending below the second spacer portion; and
wherein entire sidewalls of the first S/D opening are substantially vertical.

### Claim 15 (depends on 10)

The method of claim 10, wherein forming the first S/D region comprises forming the first S/D region with a S/D portion extending below the second spacer portion; and
wherein entire sidewalls of the S/D portion are substantially vertical.

### Claim 16

A method, comprising:
forming a fin structure on a substrate;
forming a spacer opening, in the fin structure, comprising etching the fin structure with a fluorine-based etching gas in a gas mixture comprising chlorine, hydrogen bromide, and helium, wherein a ratio of the fluorine-based etching gas to the gas mixture is about 1:10 to about 1:25;
forming a spacer along a sidewall of the fin structure and in the spacer opening; and
forming a source/drain (S/D) region comprising a first S/D portion along a sidewall of the spacer and a second S/D portion along a sidewall of the fin structure, wherein entire sidewalls of the second S/D portion are substantially vertical.

### Claim 17 (depends on 16)

The method of claim 16, wherein forming the spacer comprises forming the spacer with a sloped sidewall in contact with a sidewall of the fin structure.

### Claim 18 (depends on 16)

The method of claim 16, wherein forming the spacer opening comprises etching the fin structure with sulfur hexafluoride or carbon tetrafluoride in the gas mixture.

### Claim 19 (depends on 16)

The method of claim 16, wherein forming the spacer comprises forming the spacer with a triangular-shaped structure comprising a first sloped spacer sidewall facing the fin structure and a second sloped spacer sidewall facing the spacer opening.

### Claim 20 (depends on 19)

The method of claim 19, wherein forming the spacer comprises forming the spacer with the first sloped spacer sidewall in contact with a fin sidewall of the fin structure.