# US 10,312,338 B2 · Gate structure and method of fabricating the same

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- Number: US 10,312,338 B2
- Document ID: US10312338B2
- Status: Granted
- Kind: B2
- Application number: 16/015,392
- Filed: 2018-06-22
- Published: 2018-11-08
- Granted: 2019-06-04
- Earliest claimed: 2015-11-30
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Company Limited
- Inventors: Bo-Wen Hsieh; Yi-Chun Lo; Wen-Jia Hsieh
- Web page: https://patentgrep.com/patent/US10312338B2

## CPC

- H10D 64/518: {characterised by their lengths or sectional shapes}
- H10D 30/022: {having lightly-doped source or drain extensions selectively formed at the sides of the gates}
- H10D 30/0227: {having both lightly-doped source and drain extensions and source and drain regions self-aligned to the sides of the gate, e.g. lightly-doped drain [LDD] MOSFET or double-diffused drain [DDD] MOSFET}
- H10D 62/021: {Forming source or drain recesses by etching e.g. recessing by etching and then refilling}
- H10D 64/01318: {the conductor comprising a layer of alloy material, compound material or organic material contacting the insulator, e.g. TiN (comprising a layer of alloys of Si, Ge or C H10D64/01314)}
- 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 64/667: {the conductor comprising a layer of alloy material, compound material or organic material contacting the insulator, e.g. TiN workfunction layers (having lateral variation H10D64/671)}
- H10D 64/669: {the conductor further comprising additional layers of alloy material, compound material or organic material, e.g. TaN/TiAlN}
- H10P 50/667: {by liquid etching only}
- H10P 50/71: {using masks for conductive or resistive materials}
- H10P 76/2043: {using an anti-reflective coating}
- H10D 64/685: {being perpendicular to the channel plane}
- H10D 64/691: {comprising metallic compounds, e.g. metal oxides or metal silicates (insulators comprising nitrogen H10D64/693)}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A gate structure includes at least one spacer defining a gate region over a semiconductor substrate, a gate dielectric layer disposed on the gate region over the semiconductor substrate, a first work function metal layer disposed over the gate dielectric layer and lining a bottom surface of an inner sidewall of the spacer, and a filling metal partially wrapped by the first work function metal layer. The filling metal includes a first portion and a second portion, wherein the first portion is between the second portion and the semiconductor substrate, and the second portion is wider than the first portion.

## Claims

### Claim 1

A gate structure, comprising:
a pair of spacers defining a gate region over a semiconductor substrate;
a gate dielectric layer disposed on the gate region over the semiconductor substrate;
a first work function metal layer disposed over the gate dielectric layer and disposed between a first spacer of the pair of spacers and a second spacer of the pair of spacers, wherein the first work function metal layer has a top surface and a sidewall;
a second work function metal layer disposed over the first work function metal layer, wherein:
the second work function metal layer has a top surface, and
the sidewall of the first work function metal layer extends between the top surface of the first work function metal layer and the top surface of the second work function metal layer; and
a filling metal having a tapered sidewall in contact with the sidewall of the first work function metal layer.

### Claim 2 (depends on 1)

The gate structure of claim 1, comprising:
a protection layer over the filling metal.

### Claim 3 (depends on 2)

The gate structure of claim 2, wherein the protection layer extends between the first spacer and the second spacer.

### Claim 4 (depends on 2)

The gate structure of claim 2, wherein the protection layer has a tapered sidewall in contact with the top surface of the first work function metal layer.

### Claim 5 (depends on 1)

The gate structure of claim 1, comprising:
a protection layer in contact with the top surface of the first work function metal layer.

### Claim 6 (depends on 1)

The gate structure of claim 1, wherein the filling metal is in contact with the top surface of the second work function metal layer.

### Claim 7 (depends on 1)

The gate structure of claim 1, wherein the top surface of the first work function metal layer is sloped.

### Claim 8 (depends on 1)

The gate structure of claim 1, wherein the first work function metal layer is in contact with a sidewall of the first spacer.

### Claim 9 (depends on 1)

The gate structure of claim 1, comprising:
a third work function metal layer, wherein the third work function metal layer is spaced apart from the filling metal by the second work function metal layer.

### Claim 10 (depends on 9)

The gate structure of claim 9, wherein the second work function metal layer overlies the third work function metal layer.

### Claim 11 (depends on 9)

The gate structure of claim 9, wherein the third work function metal layer is disposed between the first work function metal layer and the second work function metal layer.

### Claim 12 (depends on 11)

The gate structure of claim 11, wherein the second work function metal layer is in contact with the first work function metal layer.

### Claim 13

A gate structure, comprising:
a first work function metal layer disposed over a gate dielectric layer and lining a portion of a sidewall of a spacer;
a second work function metal layer disposed over the first work function metal layer, wherein the second work function metal layer has a sloped top surface;
a third work function metal layer disposed over the second work function metal layer; and
a filling metal in contact with the first work function metal layer and the third work function metal layer, wherein the second work function metal layer is spaced apart from the filling metal by the third work function metal layer.

### Claim 14 (depends on 13)

The gate structure of claim 13, wherein the third work function metal layer is in contact with the first work function metal layer.

### Claim 15 (depends on 13)

The gate structure of claim 13, wherein the third work function metal layer overlies the second work function metal layer.

### Claim 16 (depends on 13)

The gate structure of claim 13, wherein a first portion of a sidewall of the first work function metal layer is in contact with the second work function metal layer and a second portion of the sidewall of the first work function metal layer is in contact with the third work function metal layer.

### Claim 17

A method of forming a gate structure, the method comprising:
forming a first work function metal layer on a sidewall of a material that defines a recess;
forming a second work function metal layer over the first work function metal layer;
removing a first portion of the second work function metal layer to expose a first portion of a sidewall of the first work function metal layer, wherein a second portion of the second work function metal layer remains on a second portion of the sidewall of the first work function metal layer after the removing;
filling the recess with a filling metal;
removing a portion of the filling metal to expose the first work function metal layer and form a second recess; and
depositing a protection layer in the second recess to contact the first work function metal layer, wherein the protection layer is spaced apart from the second portion of the second work function metal layer by the filling metal.

### Claim 18 (depends on 17)

The method of claim 17, comprising:
forming a mask layer in the recess to mask the second portion of the second work function metal layer, wherein removing the first portion of the second work function metal layer comprises:
removing the first portion of the second work function metal layer while the mask layer is masking the second portion of the second work function metal layer.

### Claim 19 (depends on 17)

The method of claim 17, comprising:
forming a third work function metal layer over the second portion of the second work function metal layer and over the first work function metal layer prior to filling the recess with the filling metal.

### Claim 20 (depends on 19)

The method of claim 19, comprising:
removing a portion of the third work function metal layer to expose at least some of the first portion of the sidewall of the first work function metal layer.