# US 12,218,225 B1 · Radical treatment in supercritical fluid for gate dielectric quality improvement to CFET structure

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- Number: US 12,218,225 B1
- Document ID: US12218225B1
- Status: Granted
- Kind: B1
- Application number: 18/390,272
- Filed: 2023-12-20
- Granted: 2025-02-04
- Earliest claimed: 2023-11-21
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Company, Ltd.
- Inventors: Cheng-Ming Lin; Kenichi Sano; Wei-Yen Woon; Szuya Liao
- Web page: https://patentgrep.com/patent/US12218225B1

## CPC

- H10D 30/024: {of fin field-effect transistors [FinFET]}
- H10D 62/121: {oriented parallel to substrates}
- H10D 30/6735: {having gates fully surrounding the channels, e.g. gate-all-around}
- H10D 30/6757: {characterised by the structure of the channel, e.g. transverse or longitudinal shape or doping profile (TFTs having channel structures for preventing kink or snapback effects H10D30/6708; TFTs having lightly-doped source or drain extensions H10D30/6715)}
- 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 64/685: {being perpendicular to the channel plane}
- H10D 84/0181: {Manufacturing their gate insulating layers}
- H10D 84/0193: {the components including FinFETs}
- H10D 84/038: {using silicon technology, e.g. SiGe}
- H10D 84/834: {comprising FinFETs}
- H10D 84/856: {the complementary IGFETs having different architectures than each other, e.g. high-voltage and low-voltage CMOS}
- H10D 88/01: {Manufacture or treatment}
- B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
- H10D 30/019: {of FETs having stacked nanowire, nanosheet or nanoribbon channels}
- H10D 30/501: {FETs having stacked nanowire, nanosheet or nanoribbon channels}
- 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 84/0144: {Manufacturing their gate insulating layers}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES

## Abstract

The present disclosure provides a method that includes providing a semiconductor structure having a bottom channel region and a top channel region over the bottom channel region; forming a gate dielectric layer over and wrapping around top channels in the top channel region; performing a radical treatment on the dielectric layer in a supercritical fluid; and forming a metal gate electrode on the dielectric layer.

## Claims

### Claim 1

A method, comprising:
providing a semiconductor structure having a bottom channel region and a top channel region over the bottom channel region, wherein the bottom channel region includes bottom channels and the top channel region includes top channels;
forming an interfacial dielectric layer to wrap around each of the top channels;
applying a first supercritical carbon dioxide fluid to the interfacial dielectric layer;
forming a high-k dielectric layer on the interfacial dielectric layer and wrapping around the each of the top channels;
applying a second supercritical carbon dioxide fluid to the high-k dielectric layer; and
forming a gate electrode on the high-k dielectric layer.

### Claim 2 (depends on 1)

The method of claim 1, wherein the applying of the first supercritical carbon dioxide fluid to the interfacial dielectric layer further includes:
dissolving a first radical source gas in the first supercritical carbon dioxide fluid; and
thereafter, applying the first supercritical carbon dioxide fluid dissolved with a first radical chemical to the interfacial dielectric layer at a temperature less than 100° C.

### Claim 3 (depends on 2)

The method of claim 2, wherein the applying of the second supercritical carbon dioxide fluid to the high-k dielectric layer further includes:
dissolving a second radical source gas in the second supercritical carbon dioxide fluid; and
thereafter, applying the second supercritical carbon dioxide fluid dissolved with a second radical chemical to the high-k dielectric layer.

### Claim 4 (depends on 3)

The method of claim 3, wherein the second radical chemical is different from the first radical chemical.

### Claim 5 (depends on 4)

The method of claim 4, wherein
the first radical chemical includes a hydrogen radical; and
the second radical chemical includes an oxygen radical.

### Claim 6 (depends on 5)

The method of claim 5, wherein
the first radical chemical includes the hydrogen radical (H*) and a deuterium radical (D*); and
the second radical chemical includes the oxygen radical (O*) and a fluorine radical (F*).

### Claim 7 (depends on 1)

The method of claim 1, wherein the providing of the semiconductor structure having the bottom channel region and the top channel region further includes:
forming the bottom channels vertically stacked on a bottom substrate;
forming a bottom source and a bottom drain on the bottom substrate, the bottom source and the bottom drain being interposed by the bottom channels;
forming a bottom gate dielectric layer wrapping around each of the bottom channels; and
performing a thermal annealing process to the bottom gate dielectric layer at a temperature greater than 900° C.

### Claim 8 (depends on 7)

The method of claim 7, wherein the providing of the semiconductor structure having the bottom channel region and the top channel region further includes:
forming a semiconductor stack of first semiconductor layers and second semiconductor layers alternatively stacked on a top substrate;
bonding the semiconductor stack formed on the top substrate to the bottom substrate; and
thinning down the top substrate such that the semiconductor stack is exposed.

### Claim 9 (depends on 8)

The method of claim 8, wherein the providing of the semiconductor structure having the bottom channel region and the top channel region further includes:
patterning the semiconductor stack to form an active region; and
forming a top source and a top drain in the active region, the top source and the top drain being interposed by the top channels.

### Claim 10

A method, comprising:
providing a semiconductor structure having a bottom channel region and a top channel region over the bottom channel region;
forming an interfacial dielectric layer that is wrapping around top channels in the top channel region;
performing a first radical treatment to the interfacial dielectric layer in a first supercritical carbon dioxide fluid having a first radical chemical dissolved therein;
forming a high-k dielectric layer over the interfacial dielectric layer and wrapping around the top channels in the top channel region;
performing a second radical treatment to the high-k dielectric layer in a second supercritical carbon dioxide fluid having a second radical chemical dissolved therein, the second radical chemical being different from the first radical chemical; and
forming a gate electrode on the high-k dielectric layer.

### Claim 11 (depends on 10)

The method of claim 10, wherein
the first radical chemical includes a hydrogen radical (H*);
the second radical chemical includes an oxygen radical (O*):
the performing of the first radical treatment to the interfacial dielectric layer includes performing the first radical treatment to the interfacial dielectric layer at a first temperature less than 100° C.; and
the performing of the second radical treatment to the high-k dielectric layer includes performing the second radical treatment to the high-k dielectric layer at a second temperature less than 100° C.

### Claim 12 (depends on 11)

The method of claim 11, wherein
the performing of the first radical treatment to the interfacial dielectric layer further includes dissolving a first radical source gas in the first supercritical carbon dioxide fluid, and applying the first supercritical carbon dioxide fluid dissolved with the first radical chemical to the interfacial dielectric layer; and
the performing of the second radical treatment to the high-k dielectric layer further includes dissolving a second radical source gas in the second supercritical carbon dioxide fluid, and applying the second supercritical carbon dioxide fluid dissolved with the second radical chemical to the high-k dielectric layer.

### Claim 13 (depends on 12)

The method of claim 12, wherein
the first radical chemical includes the hydrogen radical (H*) and a deuterium radical (D*); and
the second radical chemical includes the oxygen radical (O*), and a fluorine radical (F*).

### Claim 14 (depends on 11)

The method of claim 11, wherein the providing of the semiconductor structure having the bottom channel region and the top channel region further includes:
forming bottom channels vertically stacked in the bottom channel region on a bottom substrate;
forming a bottom source and a bottom drain on the bottom substrate, the bottom source and the bottom drain being interposed by the bottom channel region;
forming a bottom gate structure in the bottom channel region to wrap around each of the bottom channels;
performing a thermal annealing process to the bottom gate structure at a temperature greater than 900° C.;
forming a semiconductor stack of first semiconductor layers and second semiconductor layers alternatively stacked on a top substrate; and
bonding the semiconductor stack formed on the top substrate to the bottom substrate.

### Claim 15 (depends on 14)

The method of claim 14, wherein the providing of the semiconductor structure having the bottom channel region and the top channel region further includes:
thinning down the top substrate;
patterning the semiconductor stack to form an active region; and
forming a top source and a top drain in the active region, the top source and the top drain being interposed by the top channels.

### Claim 16

A method, comprising:
forming bottom channels vertically stacked in a bottom channel region on a bottom substrate;
forming a bottom source and a bottom drain on the bottom substrate, the bottom source and the bottom drain being interposed by the bottom channel region;
forming a bottom interfacial layer wrapping around each of the bottom channels;
performing a thermal annealing process to the bottom interfacial layer at a first temperature greater than 900° C.;
forming a semiconductor stack of first semiconductor layers and second semiconductor layers alternatively stacked on a top substrate;
bonding the semiconductor stack formed on the top substrate to the bottom substrate;
thinning down the top substrate such that the semiconductor stack is exposed;
patterning the semiconductor stack to form an active region;
forming a top source and a top drain in the active region, the top source and the top drain being interposed by top channels in a top channel region;
forming a top gate dielectric layer over and wrapping around the top channels in the top channel region;
performing a radical treatment to the top gate dielectric layer in a supercritical fluid at a second temperature less than 200° C., wherein the supercritical fluid includes a radical chemical; and
forming a top gate electrode to the top gate dielectric layer.

### Claim 17 (depends on 16)

The method of claim 16, wherein the forming of the top gate dielectric layer over and wrapping around the top channels in the top channel region further includes:
forming a top interfacial dielectric layer to wrap around each of the top channels, and
forming a top high-k dielectric material layer on the top interfacial dielectric layer to wrap around the each of the top channels.

### Claim 18 (depends on 17)

The method of claim 17, wherein the performing of the radical treatment to the top gate dielectric layer in the supercritical fluid further includes:
dissolving a first radical source gas in a first supercritical carbon dioxide fluid;
applying the first supercritical carbon dioxide fluid dissolved with a first radical chemical to the top interfacial dielectric layer, prior to the forming of the top high-k dielectric material layer on the top interfacial dielectric layer to wrap around the each of the top channels;
dissolving a second radical source gas in a second supercritical carbon dioxide fluid after the forming of the top high-k dielectric material layer on the top interfacial dielectric layer to wrap around the each of the top channels; and
applying the second supercritical carbon dioxide fluid dissolved with a second radical chemical to the top high-k dielectric material layer, the second radical chemical being different from the first radical chemical.

### Claim 19 (depends on 18)

The method of claim 18, wherein
the first radical chemical includes a hydrogen radical (H*); and
the second radical chemical includes an oxygen radical (O*).

### Claim 20 (depends on 19)

The method of claim 19, wherein
the first radical chemical includes the hydrogen radical (H*) and a deuterium radical (D*); and
the second radical chemical includes the oxygen radical (O*) and a fluorine radical (F*).