# US 2021/0280679 A1 · Semiconductor device and fabrication method thereof

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- Number: US 2021/0280679 A1
- Document ID: US20210280679A1
- Status: Published application
- Kind: A1
- Application number: 17/327,584
- Filed: 2021-05-21
- Published: 2021-09-09
- Earliest claimed: 2017-11-30
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Co., Ltd.
- Inventors: Cheng-Ming LIN; Peng-Soon LIM; Zi-Wei FANG
- Web page: https://patentgrep.com/patent/US20210280679A1

## CPC

- H10D 30/6219: {characterised by the source or drain electrodes}
- H10D 30/024: {of fin field-effect transistors [FinFET]}
- H10D 30/62: Fin field-effect transistors [FinFET]
- H10D 62/151: {of IGFETs (of IGFETs having LDD or DDD structure H10D30/601; of thin film transistors H10D30/6713)}
- 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 84/0135: {Manufacturing their gate conductors}
- H10D 84/0177: {the gate conductors having different materials or different implants}
- H10D 84/038: {using silicon technology, e.g. SiGe}
- H10D 84/0193: {the components including FinFETs}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A semiconductor device includes a substrate, a semiconductor fin extending from the substrate, a gate dielectric layer over the semiconductor fin, a metal nitride layer comprising a first portion over the gate dielectric layer and a second portion over the first portion, and a fill metal over the metal nitride layer. The second portion has an aluminum concentration greater than an aluminum concentration of the first portion.

## Claims

### Claim 1

A device comprising:
a substrate;
a semiconductor fin extending from the substrate;
a gate dielectric layer over the semiconductor fin;
a metal nitride layer comprising a first portion over the gate dielectric layer and a second portion over the first portion, the second portion having an aluminum concentration greater than an aluminum concentration of the first portion; and
a fill metal over the metal nitride layer.

### Claim 2 (depends on 1)

The device of claim 1, further comprising:
a p-type work function layer between the metal nitride layer and the fill metal.

### Claim 3 (depends on 1)

The device of claim 1, further comprising:
an n-type work function layer between the metal nitride layer and the fill metal.

### Claim 4 (depends on 1)

The device of claim 1, wherein the aluminum concentration of the second portion of the metal nitride layer is in a range from about 5% to about 30%.

### Claim 5 (depends on 1)

The device of claim 1, wherein the aluminum concentration of the first portion of the metal nitride layer is less than about 1%.

### Claim 6 (depends on 1)

The device of claim 1, wherein the second portion of the metal nitride layer has a thickness in a range from about 5 Angstroms to about 50 Angstroms.

### Claim 7 (depends on 1)

The device of claim 1, wherein the aluminum concentration of the second portion of the metal nitride layer is gradient.

### Claim 8 (depends on 1)

The device of claim 1, wherein both the first portion and the second portion of the metal nitride layer comprises titanium nitride or tantalum nitride.

### Claim 9 (depends on 1)

The device of claim 1, wherein the metal nitride layer further comprises a third portion over the second portion, and the third portion has a silicon concentration greater than a silicon concentration of the second portion of the metal nitride layer.

### Claim 10 (depends on 9)

The device of claim 9, wherein the third portion of the metal nitride layer has a non-zero aluminum concentration.

### Claim 11

A device comprising:
a semiconductor fin protruding above a substrate;
a gate dielectric layer over the semiconductor fin;
a first work function layer over the gate dielectric layer, an upper portion of the first work function layer having a silicon concentration greater than a silicon concentration of a lower portion of the first work function layer; and
a second work function layer over the first work function layer and having a work function lower than a work function of the first work function layer.

### Claim 12 (depends on 11)

The device of claim 11, wherein the silicon concentration of the upper portion of the first work function layer is in a range from about 5% to about 30%.

### Claim 13 (depends on 11)

The device of claim 11, wherein the silicon concentration of the lower portion of the first work function layer is less than about 1%.

### Claim 14 (depends on 11)

The device of claim 11, wherein the upper portion of the first work function layer has a thickness in a range from about 5 Angstroms to about 50 Angstroms.

### Claim 15 (depends on 11)

The device of claim 11, wherein the upper portion of the first work function layer comprises silicon nitride.

### Claim 16 (depends on 11)

The device of claim 11, wherein the work function of the first work function layer is higher than a mid-gap work function that is at a middle level of a valance band and a conduction band of silicon.

### Claim 17 (depends on 11)

The device of claim 11, wherein the work function of the second work function layer is lower than a mid-gap work function that is at a middle level of a valance band and a conduction band of silicon.

### Claim 18

A device comprising:
a semiconductor fin over a substrate;
a gate dielectric layer over the semiconductor fin;
a p-type work function layer over the gate dielectric layer, an upper portion of the p-type work function layer being doped with aluminum; and
an n-type work function layer over the aluminum-doped upper portion of the p-type work function layer.

### Claim 19 (depends on 18)

The device of claim 18, wherein the upper portion of the p-type work function layer has an aluminum concentration greater than an aluminum concentration of a lower portion of the p-type work function layer.

### Claim 20 (depends on 18)

The device of claim 18, wherein the upper portion of the p-type work function layer has an aluminum concentration increasing as a distance from the substrate increases.