Positive Resist Composition for Acid Diffusion Control in EUV Lithography

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Solution Overview

Problem

Existing chemically amplified resist compositions face challenges in achieving high resolution, improved line edge roughness (LER), fidelity, and dose margin due to uncontrolled acid diffusion, which affects sensitivity and pattern profile, especially in advanced lithography processes like EUV and EB lithography.

Innovation Solution

A chemically amplified positive resist composition comprising a quencher in the form of an onium salt with specific anions forming a conjugate acid of low boiling point and molecular weight, combined with a base polymer and a photoacid generator, effectively controlling acid diffusion and enhancing pattern formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If acid diffusion is not controlled, then deprotection reaction occurs in unexposed regions, but this causes lowering of line edge roughness (LER) and degradation of critical dimension uniformity (CDU)

Engineering Contradiction:

Improvedeprotection reaction controlVSAvoidline edge roughness and critical dimension uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent introduces a quencher as an intermediary substance that interacts with the acid generated during exposure. The quencher selectively neutralizes diffused acid in unexposed regions without affecting the acid in exposed regions, thereby preventing unwanted deprotection reactions while maintaining pattern fidelity and improving LER and CDU

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the chemical parameters of the resist composition by adding a quencher with specific properties (basicity, concentration, molecular weight). This parameter change enables selective control of acid-base reactions, allowing deprotection in exposed regions while preventing it in unexposed regions, thus resolving the contradiction between reaction completeness and pattern precision

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If high-energy radiation exposure is used to form fine patterns, then resolution is improved, but acid diffusion affects sensitivity and pattern profile

Engineering Contradiction:

Improvepattern resolutionVSAvoidsensitivity and pattern profile

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The quencher acts as a mediator between the photoacid generator and the polymer matrix, controlling the spatial distribution and effectiveness of generated acid. It allows high-energy radiation to produce fine patterns while preventing acid diffusion from compromising sensitivity and pattern profile by neutralizing stray acid

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If acetal groups are used as acid-decomposable protective groups, then resist sensitivity is improved, but uncontrolled acid diffusion causes deprotection in unexposed regions

Engineering Contradiction:

Improveresist sensitivityVSAvoidpattern fidelity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The quencher serves as a protective intermediary that selectively neutralizes acid in unexposed regions, preventing premature deprotection of acetal groups. This allows the use of highly sensitive acetal-based polymers while maintaining pattern fidelity by controlling where deprotection occurs

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The quencher creates local chemical environment differences: in unexposed regions, the quencher neutralizes acid to prevent deprotection, while in exposed regions, the high acid concentration overcomes the quencher's buffering capacity to enable deprotection. This local quality differentiation resolves the contradiction between sensitivity and fidelity

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The resist composition achieves high resolution, improved LER, fidelity, and dose margin, resulting in a satisfactory resist pattern profile suitable for EUV and EB lithography processes.

Implementation Method 1

Upon exposure to high-energy radiation, the acid-decomposable protective group is deprotected by the catalysis of an acid generated from a photoacid generator

Methodology Applied

Scientific EffectPhotolysis: Photodissociation

Implementation Method 2

if the diffusion of generated acid is not fully controlled, deprotection reaction can occur even in the unexposed region of the resist film

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 3

the acid-decomposable protective group is deprotected by the catalysis of an acid generated from a photoacid generator

Methodology Applied

Scientific EffectCatalysis: Catalysis

Data Source

PatentUS20260064001A1Chemically amplified positive resist composition and resist pattern forming process

Publication Date: 2026.03.05 SHIN ETSU CHEMICAL CO LTD

AI summary

A chemically amplified positive resist composition comprising (A) a quencher in the form of an onium salt containing an anion (Xq−) which forms a conjugate acid (XqH) having a boiling point of lower than 165° C. and a molecular weight of up to 150, (B) a base polymer, and (C) a photoacid generator exhibits a high resolution and forms a pattern of satisfactory profile with low LER, fidelity and improved dose margin.