# US 12,218,199 B2 · Transistor gate structures and methods of forming the same

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- Number: US 12,218,199 B2
- Document ID: US12218199B2
- Status: Granted
- Kind: B2
- Application number: 18/333,981
- Filed: 2023-06-13
- Published: 2023-10-12
- Granted: 2025-02-04
- Earliest claimed: 2021-01-28
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Co., Ltd.
- Inventors: Hsin-Yi Lee; Jia-Ming Lin; Chi On Chui
- Web page: https://patentgrep.com/patent/US12218199B2

## CPC

- H10D 62/121: {oriented parallel to substrates}
- H10D 64/01316: {the conductor comprising a layer of elemental metal contacting the insulator, e.g. Ta, W, Mo or Al}
- H10D 30/019: {of FETs having stacked nanowire, nanosheet or nanoribbon channels}
- H10D 30/501: {FETs having stacked nanowire, nanosheet or nanoribbon channels}
- 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 84/0193: {the components including FinFETs}
- H10D 84/038: {using silicon technology, e.g. SiGe}
- H10D 84/851: {comprising IGFETs having stacked nanowire, nanosheet or nanoribbon channels}
- H10D 84/853: {comprising FinFETs}
- H10P 30/206: {into Group III-V semiconductors}
- H10P 30/208: {of electrically inactive species}
- B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
- H10D 30/797: {being in source or drain regions, e.g. SiGe source or drain}
- H10D 62/822: comprising only Group IV materials heterojunctions, e.g. Si/Ge heterojunctions
- H10D 64/01: Manufacture or treatment
- H10W 20/069: {by forming self-aligned vias or self-aligned contact plugs}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

In an embodiment, a device includes: a first nanostructure; a second nanostructure; a gate dielectric around the first nanostructure and the second nanostructure, the gate dielectric including dielectric materials; and a gate electrode including: a work function tuning layer on the gate dielectric, the work function tuning layer including a pure work function metal, the pure work function metal of the work function tuning layer and the dielectric materials of the gate dielectric completely filling a region between the first nanostructure and the second nanostructure, the pure work function metal having a composition of greater than 95 at. % metals; an adhesion layer on the work function tuning layer; and a fill layer on the adhesion layer.

## Claims

### Claim 1

A device comprising:
a first nanostructure;
a second nanostructure;
a gate dielectric around the first nanostructure and the second nanostructure; and
a gate electrode comprising:
a work function tuning layer on the gate dielectric, the work function tuning layer and the gate dielectric completely filling a region between the first nanostructure and the second nanostructure, the work function tuning layer comprising a multi-layer of pure work function metals, an upper one of the pure work function metals having a different thickness than a lower one of the pure work function metals;
an adhesion layer on the work function tuning layer; and
a fill layer on the adhesion layer.

### Claim 2 (depends on 1)

The device of claim 1, wherein respective metals of the pure work function metals have interfaces comprising alloys of the respective metals.

### Claim 3 (depends on 1)

The device of claim 1, wherein respective metals of the pure work function metals have interfaces free of alloys of the respective metals.

### Claim 4 (depends on 1)

The device of claim 1, wherein the adhesion layer comprises an impure metal and the fill layer comprises a fill metal, the impure metal of the adhesion layer having a greater concentration of metalloids and nonmetals than the fill metal of the fill layer and the pure work function metals of the work function tuning layer.

### Claim 5 (depends on 1)

The device of claim 1, further comprising:
an n-type source/drain region adjacent the first nanostructure and the second nanostructure, the work function tuning layer comprising pure titanium, pure aluminum, or pure hafnium.

### Claim 6 (depends on 1)

The device of claim 1, further comprising:
a p-type source/drain region adjacent the first nanostructure and the second nanostructure, the work function tuning layer comprising pure tungsten, pure nickel, or pure platinum.

### Claim 7 (depends on 1)

The device of claim 1, wherein the upper one of the pure work function metals has a first portion around the first nanostructure and has a second portion around the second nanostructure, the first portion and the second portion contacting to form an interface.

### Claim 8

A device comprising:
a channel region;
a gate dielectric on the channel region;
a first work function metal on the gate dielectric, the first work function metal having a first concentration of non-metal elements;
a second work function metal on the first work function metal, the second work function metal different from the first work function metal, the second work function metal having a different thickness than the first work function metal, the second work function metal having a second concentration of the non-metal elements;
an adhesion metal on the second work function metal, the adhesion metal having a third concentration of the non-metal elements, the third concentration greater than the first concentration and the second concentration; and
a fill metal on the adhesion metal.

### Claim 9 (depends on 8)

The device of claim 8, wherein an interface of the first work function metal and the second work function metal is free of an alloy of the first work function metal and the second work function metal.

### Claim 10 (depends on 8)

The device of claim 8, wherein an interface of the first work function metal and the second work function metal comprises an alloy of the first work function metal and the second work function metal.

### Claim 11 (depends on 8)

The device of claim 8, wherein the first work function metal comprises titanium, aluminum, or hafnium, and the second work function metal comprises titanium, aluminum, or hafnium.

### Claim 12 (depends on 8)

The device of claim 8, wherein the first work function metal comprises tungsten, nickel, or platinum, and the second work function metal comprises tungsten, nickel, or platinum.

### Claim 13

A method comprising:
forming a first nanostructure and a second nanostructure;
forming a gate dielectric having a first portion around the first nanostructure and having a second portion around the second nanostructure;
depositing one or more work function metals over the gate dielectric, the work function metals completely filling an opening between the first portion of the gate dielectric and the second portion of the gate dielectric, the work function metals comprising impurities, the impurities comprising metalloids or nonmetals;
applying a purification treatment to the work function metals, the purification treatment reducing a first concentration of the impurities in the work function metals;
after applying the purification treatment to the work function metals, depositing an adhesion metal over the work function metals, the adhesion metal comprising the impurities; and
depositing a fill metal over the adhesion metal.

### Claim 14 (depends on 13)

The method of claim 13, wherein a second concentration of the impurities in the adhesion metal is less than the first concentration.

### Claim 15 (depends on 13)

The method of claim 13, wherein the impurities are nitrogen or carbon.

### Claim 16 (depends on 13)

The method of claim 13, wherein the purification treatment comprises:
annealing the work function metals.

### Claim 17 (depends on 13)

The method of claim 13, wherein the purification treatment comprises:
bombarding the work function metals with ions.

### Claim 18 (depends on 13)

The method of claim 13, wherein the purification treatment comprises:
exposing the work function metals to a reduction chemical, the reduction chemical comprising hydrogen or a metal hydride.

### Claim 19 (depends on 13)

The method of claim 13, wherein the one or more work function metals are a single layer of pure work function metal.

### Claim 20 (depends on 13)

The method of claim 13, wherein the one or more work function metals are a multi-layer of different pure work function metals.