Resist Protective Coating Composition for ArF Lithography

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Solution Overview

Problem

ArF immersion lithography faces issues with pattern profile changes and defects due to acid leaching and water penetration, and existing protective coatings either fail to prevent leaching or introduce hydrophilicity that leads to water marks and film slimming.

Innovation Solution

A resist protective coating composition comprising a copolymer of alkali-soluble (α-trifluoromethyl)acrylate and norbornene derivatives, optionally blended with sulfonic acid and sulfonic acid amine salts, is applied to minimize development defects and maintain a satisfactory pattern profile.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protective coating is applied to prevent acid leaching and water penetration, then resist stability is improved, but water marks and film slimming occur due to hydrophilicity

Engineering Contradiction:

Improveresist stabilityVSAvoidwater marks and film slimming

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The protective coating is designed with spatially differentiated properties: the lower portion contacts the resist film to prevent acid leaching, while the upper portion contacts water to provide water repellency. This local differentiation allows each region to perform its specific function optimally without compromising the other.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The protective coating uses a composite structure combining a water-soluble polymer base with hydrophobic inorganic particles. This composite material simultaneously provides water solubility for easy removal, water repellency through inorganic particles, and resistance to film slimming through the synergistic interaction of coating components.

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If fluorinated compounds are used for protective coating, then water repellency is improved, but environmental and cost issues arise

Engineering Contradiction:

Improvewater repellencyVSAvoidenvironmental and cost issues

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

Instead of using fluorinated compounds, the invention changes the approach by incorporating hydrophobic inorganic particles into a water-soluble polymer matrix. This parameter change maintains water repellency while eliminating the environmental and cost problems associated with fluorine-based materials.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The protective coating is designed to be water-soluble and easily removable, functioning as a disposable protective layer during the lithography process. This eliminates the need for complex stripping processes and reduces waste management costs compared to fluorinated coatings.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of manufacture

If water-soluble or alkali-soluble materials are used for protective coating, then stripping is simplified, but leaching prevention is insufficient

Engineering Contradiction:

Improvestripping simplicityVSAvoidleaching prevention

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The protective coating combines water-soluble polymer chains with hydrophobic inorganic particles in a composite structure. The polymer matrix provides water solubility for easy stripping, while the inorganic particles provide hydrophobicity to prevent water penetration and acid leaching, achieving both stripping simplicity and effective protection.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Within the protective coating structure, different regions serve different functions: the polymer matrix regions provide water solubility for easy removal, while the inorganic particle regions provide hydrophobic protection against leaching. This local quality differentiation allows the coating to be both easily stripped and effective in preventing leaching.

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 coating composition effectively reduces leaching and water penetration, maintaining a satisfactory pattern profile with minimal defects and allowing for efficient alkaline development while preventing film slimming.

Implementation Method 1

the acid once generated from a photoacid generator and a basic compound added to the resist can be partially leached in water

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

providing a protective coating between the resist film and water to prevent resist components from being leached out and water from penetrating into the resist film

Methodology Applied

Scientific EffectHydrophobe: Hydrophobe

Implementation Method 3

A resist protective coating composition comprising a copolymer of alkali-soluble (α-trifluoromethyl)acrylate and norbornene derivatives

Methodology Applied

Scientific EffectSolvation: Solvation

Data Source

PatentUS8158330B2Resist protective coating composition and patterning process

Publication Date: 2012.04.17 SHIN ETSU CHEMICAL CO LTD

AI summary

A protective coating composition comprising a copolymer of an alkali-soluble (α-trifluoromethyl) acrylate and a norbornene derivative as a base polymer, optionally in admixture with a second polymer containing sulfonic acid and/or sulfonic acid amine salt in repeat units is applied onto a resist film. The protective coating is effective in minimizing development defects and forming a resist pattern of improved profile.