Positive Resist Composition Using Polyhydric Phenol Mediator

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Solution Overview

Problem

Current positive resist compositions used in lithography face challenges with resolution and edge roughness, particularly in ArF and EUV lithography, due to acid diffusion and alkaline developer swell, which affect pattern accuracy and dry etching resistance.

Innovation Solution

A polymer comprising recurring units derived from vinylanthraquinone, acid labile group-substituted hydroxystyrene, and hydroxystyrene is used as a base resin, which controls acid diffusion and alkaline dissolution uniformity, resulting in high resolution and minimal edge roughness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a chemically amplified resist composition is used to increase EB writing throughput, then sensitivity is improved, but resolution and pattern accuracy are reduced due to acid diffusion

Engineering Contradiction:

ImproveEB writing throughputVSAvoidpattern accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

A polyhydric phenol compound is introduced as an intermediary substance between the acid generator and the polymer. This mediator selectively captures excess difluorosulfonic acid through hydrogen bonding, preventing it from causing unintended chemical amplification and image blur. The polyhydric phenol acts as a buffer that controls acid diffusion while maintaining the sensitivity benefits of chemically amplified resist, thereby resolving the contradiction between throughput improvement and pattern accuracy

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical parameters of the resist system by incorporating a polyhydric phenol compound with specific molecular weight (500-5000) and specific functional groups. This parameter change modifies the acid-base interaction dynamics in the resist, allowing controlled acid diffusion that maintains resolution while preserving the high sensitivity of chemically amplified formulations

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the resolution of resist pattern is improved, then the aspect ratio of resist pattern increases, but pattern collapse occurs due to stresses during rinsing and drying

Engineering Contradiction:

Improveresist pattern resolutionVSAvoidpattern collapse resistance

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The invention creates a composite resist system combining the polyhydric phenol compound with specific polymers (polyhydroxystyrene derivatives and/or polyacrylic acid derivatives). This composite formulation provides both high resolution through controlled acid diffusion and mechanical stability through the synergistic interaction of components, preventing pattern collapse while maintaining fine pattern resolution

Inventive Principle:

Principle #40Composite materials

3Strength

If indene or acenaphthylene copolymers are used to improve dry etching resistance, then etching resistance is improved, but resolution deteriorates due to uncontrolled acid diffusion

Engineering Contradiction:

Improvedry etching resistanceVSAvoidresolution

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The polyhydric phenol compound serves as an intermediary that overrides the uncontrolled acid diffusion tendency of indene/acenaphthylene copolymers. By selectively binding excess acid, it prevents acid from diffusing laterally and degrading resolution, while allowing the copolymer's dry etching resistance properties to be fully utilized

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention applies local quality control by having the polyhydric phenol compound act locally at acid generation sites to capture difluorosulfonic acid. This localized acid capture maintains sharp pattern edges (high resolution) while the bulk polymer structure (indene/acenaphthylene copolymer) provides the desired dry etching resistance

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 polymer-based positive resist composition achieves high contrast, suppressed acid diffusion, improved resolution, and reduced edge roughness, making it suitable for fine pattern formation in VLSIs and photomasks.

Implementation Method 1

resolution and pattern accuracy are reduced by image blur due to acid diffusion

Methodology Applied

Scientific EffectAcid diffusion: Diffusion

Implementation Method 2

a chemically amplified resist composition is generally used

Methodology Applied

Scientific EffectChemical amplification: Chemical Bonding

Data Source

PatentUS10191372B2Polymer, positive resist composition, and pattern forming process

Publication Date: 2019.01.29 SHIN ETSU CHEMICAL CO LTD

AI summary

A polymer comprising recurring units derived from vinylanthraquinone, recurring units derived from acid labile group-substituted hydroxystyrene, and recurring units derived from hydroxystyrene is provided. The polymer is used as a base resin to formulate a positive resist composition having a high resolution and minimal LER.