Betaine Iodonium Salt Quencher for EUV Resist Acid Diffusion Control

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Solution Overview

Problem

Existing chemically amplified resist compositions face challenges in controlling acid diffusion, leading to issues such as degradation of line edge roughness (LER) and critical dimension uniformity (CDU) during the formation of small feature sizes in semiconductor patterns, particularly in EB and EUV lithography, due to insufficient control over acid diffusion and solubility of polymers with acidic side chains.

Innovation Solution

A iodonium salt with a betaine-type structure containing a C6-C18 chainlike alkyl or C4-C18 fluorinated alkyl group is used as a quencher in a chemically amplified positive resist composition, which effectively controls acid diffusion and enhances solvent solubility, resulting in improved lithography properties like resolution, LER, and pattern profile.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If polymers with acidic side chains are used to control acid diffusion, then acid diffusion is controlled, but solvent solubility deteriorates

Engineering Contradiction:

Improveacid diffusion controlVSAvoidsolvent solubility

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent introduces a base polymer as an intermediary substance that binds to the acidic side chains. This base polymer acts as a mediator that controls acid diffusion while maintaining the solubility of the resist composition in organic solvents, resolving the contradiction between acid diffusion control and solvent solubility.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a composite resist composition by combining a base polymer with acidic side chains. This composite material achieves both acid diffusion control through the acidic groups and maintains solvent solubility through the base polymer matrix, solving the contradiction between these two properties.

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If acid generators are used to generate bulky acids, then acid diffusion is controlled, but resolution and pattern profile deteriorate

Engineering Contradiction:

Improveacid diffusion controlVSAvoidresolution

Core Design Contradiction:

Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The patent changes the parameters of the acid generator to produce acids with specific bulkiness and diffusion characteristics. By adjusting the structure and properties of the acid generator, the patent achieves controlled acid diffusion while maintaining high resolution and sharp pattern profiles.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If conventional iodonium salts are used as quenchers, then acid diffusion is suppressed, but solvent solubility deteriorates

Engineering Contradiction:

Improveacid diffusion suppressionVSAvoidsolvent solubility

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent modifies the parameters of the iodonium salt structure, specifically introducing a fluorinated alkyl group. This structural parameter change enhances the solvent solubility of the iodonium salt while maintaining its ability to suppress acid diffusion, resolving the contradiction between acid diffusion suppression and solvent solubility.

Inventive Principle:

Principle #35Parameter changes

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 iodonium salt composition achieves high-resolution, rectangular pattern profiles with reduced LER and improved CDU, particularly in EB and EUV lithography, by effectively suppressing excessive deprotection reactions and controlling acid diffusion.

Implementation Method 1

One of the important applications of chemically amplified resist material resides in processing of photomask blanks... the diffusion of acid, which has a significant impact on the resolution of a chemically amplified resist film

Methodology Applied

Scientific EffectAcid diffusion control: Diffusion

Implementation Method 2

a sulfonic acid to be generated upon exposure is bound to a polymer for use in a resist composition for controlling acid diffusion

Methodology Applied

Scientific EffectAcid binding: Absorption (physical)

Implementation Method 3

For exposure of these resist compositions, high-energy radiation such as UV, deep-UV or EB is used as the energy source

Methodology Applied

Scientific EffectElectron beam irradiation: Electron Beam

Implementation Method 4

acid generators capable of generating bulky acids upon exposure

Methodology Applied

Scientific EffectPhotoacid generation: Photodissociation

Implementation Method 5

a polymer having an acidic functional group on phenol side chain masked with an acid labile group (or acid-decomposable protective group). Upon exposure to high-energy radiation, the acid labile group is deprotected by the catalysis of an acid generated from a photoacid generator

Methodology Applied

Scientific EffectAcid-catalyzed decomposition: Decomposition (biological)

Data Source

PatentUS20260056469A1Iodonium salt, chemically amplified positive resist composition and resist pattern forming process

Publication Date: 2026.02.26 SHIN ETSU CHEMICAL CO LTD

AI summary

A betaine type iodonium salt containing a C6-C18 alkyl or C4-C18 fluorinated alkyl group and having a iodonium cation and a carboxylate anion within a common molecule is a useful quencher. A chemically amplified positive resist composition comprising the iodonium salt exhibits improved lithography properties such as resolution, LER and pattern profile when processed by photolithography.