Acrylate Resist Composition for ArF Lithography Resolution

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Solution Overview

Problem

Chemically amplified resists using polyhydroxystyrene-based resins suffer from low resolution when exposed to light with wavelengths shorter than 248 nm, such as 193 nm, due to inadequate transparency and high line edge roughness (LER) and rounded pattern shapes, which affect the formation of fine semiconductor elements.

Innovation Solution

A positive resist composition combining specific structural units from acrylate esters with an onium salt having a specific anion portion, including structural units with acetal groups and lactone-containing groups, to enhance alkali solubility and pattern resolution, reducing LER and improving shape fidelity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If polyhydroxystyrene-based resins are used as base resin, then high transparency at KrF wavelength (248 nm) is achieved, but resolution deteriorates at shorter wavelengths (193 nm) due to inadequate transparency

Engineering Contradiction:

ImprovetransparencyVSAvoidresolution

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent changes the chemical composition parameters of the base resin by switching from polyhydroxystyrene-based to acrylic resin-based materials, which fundamentally alters the optical properties to achieve both high transparency at KrF wavelength and high resolution at ArF wavelength

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite resin system combining acrylic resin base material with specific functional groups (carboxyl, hydroxyl, or amine) to achieve both optical transparency and chemical functionality for chemically amplified resist process

Inventive Principle:

Principle #40Composite materials

2Strength

If tertiary ester compounds of (meth)acrylic acid are used, then high dissociation energy is achieved, but adaptability of acid generators is restricted

Engineering Contradiction:

Improvedissociation energyVSAvoidacid generator compatibility

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The patent changes the functional group parameter from tertiary ester to carboxyl/hydroxyl/amine groups, which have lower dissociation energy and broader compatibility with various acid generators while maintaining sufficient acid-dissociable behavior

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs readily available and cost-effective acid generators such as oxime sulfonate-based compounds that can efficiently generate acid for the resist process without requiring expensive or specialized reagents

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If acetal groups are used as acid-dissociable groups, then sensitivity is improved, but line edge roughness increases and pattern shape deteriorates

Engineering Contradiction:

ImprovesensitivityVSAvoidline edge roughness

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the chemical structure parameter by introducing carboxyl, hydroxyl, or amine groups instead of acetal groups, which modifies the acid-dissociation characteristics to reduce line edge roughness while maintaining sensitivity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent combines multiple functional groups (carboxyl, hydroxyl, and/or amine) within the resin structure to achieve a balance between sensitivity, line edge roughness control, and pattern shape fidelity

Inventive Principle:

Principle #40Composite materials

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 composition achieves reduced LER and improved pattern shape with enhanced resolution and rectangular formability, suitable for forming fine semiconductor elements using ArF excimer laser lithography.

Implementation Method 1

an acid generator (B) that generates acid on exposure

Methodology Applied

Scientific EffectPhotochemical reaction: Photopolymerisation

Implementation Method 2

positive resists in which the alkali solubility of the exposed portions increases

Methodology Applied

Scientific EffectChemical dissolution: Solvation

Data Source

PatentUS7803512B2Positive resist composition and method of forming resist pattern

Publication Date: 2010.09.28 TOKYO OHKA KOGYO CO LTD

AI summary

A positive resist composition that includes a resin component (A) that exhibits increased alkali solubility under the action of acid, and an acid generator component (B) that generates acid on exposure to radiation, wherein the component (A) includes a structural unit (a1) represented by a general formula (a1-2) or (a1-4), a structural unit (a2) derived from an acrylate ester that contains a lactone-containing monocyclic or polycyclic group, and a structural unit (a3), which is different from the structural unit (a1) and the structural unit (a2), and is derived from an acrylate ester that contains an aliphatic cyclic group-containing non-acid-dissociable, dissolution-inhibiting group and contains no polar groups, and the component (B) includes an onium salt (B1) having an anion portion represented by a formula: R41—SO3−.