# US 2022/0037152 A1 · Plasma Pre-Treatment Method To Improve Etch Selectivity And Defectivity Margin

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- Number: US 2022/0037152 A1
- Document ID: US20220037152A1
- Status: Published application
- Kind: A1
- Application number: 17/328,284
- Filed: 2021-05-24
- Published: 2022-02-03
- Earliest claimed: 2020-07-30
- Assignees: Tokyo Electron Limited
- Applicants: Tokyo Electron Limited
- Inventors: Angelique Raley; Qiaowei Lou; Katie Lutker-Lee
- Web page: https://patentgrep.com/patent/US20220037152A1

## CPC

- H10P 14/6514: {by exposure to a plasma}
- H10P 76/405: {characterised by their composition, e.g. multilayer masks}
- H10P 50/283: {by chemical means}
- H10P 50/73: {using masks for insulating materials}
- H10P 76/2043: {using an anti-reflective coating}
- H10P 14/6518: {by introduction of substances into an already-existing insulating layer}
- H10P 14/6532: {by exposure to a plasma}
- H10P 14/69433: {the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz}
- H10P 30/40: into insulating materials
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Improved methods are provided for transferring a photoresist pattern onto one or more underlying layers. In the disclosed embodiments, etch selectivity between a photoresist layer and one or more underlying layers is improved by pre-treating the underlying layer(s) with a plasma before the photoresist layer is deposited and patterned to form a photoresist pattern. The plasma modifies the underlying layer(s) by implanting ions into the underlying layer(s) to form a modified layer. When the modified layer is subsequently etched to transfer the photoresist pattern onto the modified layer, the presence of ions within the modified layer increases the etch rate of the modified layer, compared to the etch rate that the underlying layer(s) would have exhibited without plasma pre-treatment. The increased etch rate of the modified layer improves etch selectivity between the photoresist layer and the modified layer and mitigates defects during the photoresist pattern transfer process.

## Claims

### Claim 1

A method for processing a substrate, comprising:
providing the substrate with at least one underlying layer;
pre-treating the at least one underlying layer with a plasma to modify the at least one underlying layer, wherein ions from the plasma are implanted into the at least one underlying layer to form a modified layer;
providing a photoresist layer overlying the modified layer;
using a lithography technique to form a photoresist pattern in the photoresist layer; and
removing portions of the modified layer exposed by the photoresist pattern to transfer the photoresist pattern onto the modified layer,
wherein the pre-treating the underlying layer with the plasma increases a rate at which the modified layer is removed compared to without pre-treatment.

### Claim 2 (depends on 1)

The method of claim 1, wherein the plasma is generated from one or more processing gases selected from a group comprising hydrogen (H2), helium (He), argon (Ar), nitrogen (N2), borane (BH3), and phosphine (PH3).

### Claim 3 (depends on 2)

The method of claim 2, wherein the one or more processing gases comprise hydrogen (H2).

### Claim 4 (depends on 1)

The method of claim 1, wherein the at least one underlying layer comprises a hard mask layer.

### Claim 5 (depends on 1)

The method of claim 1, wherein the at least one underlying layer comprises a silicon-containing material.

### Claim 6 (depends on 1)

The method of claim 1, wherein the photoresist layer is an extreme ultraviolet (EUV) photoresist layer, and wherein the lithography technique is an EUV lithography technique.

### Claim 7 (depends on 1)

The method of claim 1, wherein the removing portions of the modified layer comprises performing an etch process to open the portions of the modified layer exposed by the photoresist pattern.

### Claim 8 (depends on 7)

The method of claim 7, wherein the pre-treating the underlying layer with the plasma increases an etch rate of the modified layer compared to an etch rate of the underlying layer without pre-treatment.

### Claim 9 (depends on 8)

The method of claim 8, wherein increasing the etch rate of the modified layer improves etch selectivity between the modified layer and the photoresist layer.

### Claim 10 (depends on 1)

The method of claim 1, wherein the pre-treating the underlying layer with the plasma improves line width roughness (LWR), line edge roughness (LER), contact edge roughness (CER) and/or local critical dimension uniformity (LCDU).

### Claim 11

A method for processing a substrate, comprising:
providing the substrate with at least one underlying layer;
pre-treating the at least one underlying layer with a plasma to modify the at least one underlying layer, wherein the plasma is generated from one or more processing gases comprising hydrogen (H2), nitrogen (N2), borane (BH3), phosphine (PH3) and/or a noble gas, and wherein ions from the plasma are implanted into the at least one underlying layer to form a modified layer;
providing an extreme ultraviolet (EUV) photoresist layer overlying the modified layer;
using an EUV lithography technique to form an EUV photoresist pattern in the EUV photoresist layer; and
etching portions of the modified layer exposed by the EUV photoresist pattern with a dry etch process to transfer the EUV photoresist pattern onto the modified layer,
wherein the pre-treating the at least one underlying layer with the plasma increases an etch rate of the modified layer and improves dry etch selectivity over the EUV photoresist layer.

### Claim 12 (depends on 11)

The method of claim 11, wherein the at least one underlying layer comprises a silicon containing material.

### Claim 13 (depends on 11)

The method of claim 11, wherein the one or more processing gases comprise hydrogen (H2).

### Claim 14 (depends on 11)

The method of claim 11, further comprising controlling a bias voltage used to generate the plasma to control ion energy, which in turn, controls ion implantation depth, and thus, a thickness of the modified layer.

### Claim 15 (depends on 11)

The method of claim 11, wherein the dry etch process is a plasma etch process.

### Claim 16

A method for processing a substrate, comprising:
providing the substrate with at least one underlying layer, wherein the at least one underlying layer comprises a silicon-containing material;
pre-treating the at least one underlying layer with a hydrogen (H2) plasma to modify the at least one underlying layer, wherein H and H2 ions from the hydrogen plasma are implanted into the at least one underlying layer to form a modified layer;
providing a photoresist layer overlying the modified layer;
using a lithography technique to form a photoresist pattern in the photoresist layer; and
etching portions of the modified layer exposed by the photoresist pattern to transfer the photoresist pattern onto the modified layer and form a modified layer pattern,
wherein the pre-treating the at least one underlying layer with the hydrogen plasma improves an etch selectivity during said etching and improves defectivity margin in the modified layer pattern.

### Claim 17 (depends on 16)

The method of claim 16, wherein the photoresist layer is an extreme ultraviolet (EUV) photoresist layer.

### Claim 18 (depends on 16)

The method of claim 16, wherein the pre-treating the at least one underlying layer with the hydrogen plasma improves the etch selectivity by increasing an etch rate of the modified layer compared to an etch rate of the at least one underlying layer without pre-treatment.

### Claim 19 (depends on 18)

The method of claim 18, wherein the etch rate of the modified layer is 1.5 to 10 times greater than the etch rate of the underlying layer without pre-treatment.

### Claim 20 (depends on 18)

The method of claim 18, wherein the photoresist layer is an extreme ultraviolet (EUV) photoresist layer.