Positive Resist Composition for ArF Lithography

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Solution Overview

Problem

Current micropatterning technologies using ArF excimer laser lithography face challenges with line edge roughness, exposure dose dependency, pattern density dependency, and mask fidelity, which affect the performance and resolution of semiconductor devices.

Innovation Solution

A positive resist composition comprising a polymer with specific recurring units and a sulfonium salt compound as an acid generator, which minimizes line edge roughness and enhances pattern rectangularity when processed by ArF excimer laser photolithography.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the molecular weight of resin is set at a relatively low level or a photoacid generator with high acid mobility is selected, then line edge roughness is reduced, but exposure dose dependency, pattern density dependency, and mask fidelity are extremely exacerbated

Engineering Contradiction:

Improveline edge roughnessVSAvoidexposure dose dependency, pattern density dependency, and mask fidelity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent changes the chemical structure parameters of the resin by introducing specific recurring units (formula 1) with controlled ratios (a+b+c=1, where a,b,c are between 0.01 and less than 1). This structural modification optimizes the balance between line edge roughness and pattern fidelity without requiring extreme parameter changes like very low molecular weight

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite resin system combining multiple recurring units (formula 1) with different functional characteristics. The combination of units with different R1, R2, m, n, and p values creates a synergistic material that simultaneously improves line edge smoothness and maintains pattern fidelity, avoiding the trade-off present in single-component systems

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If monocyclic lactone units with high developer affinity are introduced to reduce line edge roughness, then line edge roughness is reduced, but acid diffusion is not sufficiently held down, resulting in insufficient resolution

Engineering Contradiction:

Improveline edge roughnessVSAvoidresolution

Core Design Contradiction:

Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The patent applies local quality by introducing specific recurring units (formula 1) with controlled local concentrations (ratios a, b, c). These units provide localized developer affinity to smooth line edges while the overall resin composition maintains sufficient acid diffusion control for high resolution

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent modifies the chemical parameters of the resin by incorporating recurring units with specific structural parameters (R1, R2, m, n, p) and controlling their ratios. This parameter optimization achieves the dual goal of reducing line edge roughness while maintaining resolution through controlled acid diffusion

Inventive Principle:

Principle #35Parameter changes

3Length of moving object

If the pattern rule is further reduced to enable miniaturization, then higher integration and operating speeds are achieved, but line edge roughness and pattern fidelity become more critical and difficult to control

Engineering Contradiction:

Improvepattern ruleVSAvoidline edge roughness and pattern fidelity

Core Design Contradiction:

Length of moving objectVSManufacturing precision

Solution Approach 1:

The patent optimizes the chemical parameters of the resist material by introducing recurring units with specific structural characteristics and controlling their ratios. This material parameter optimization enables the system to maintain high manufacturing precision even when the pattern rule is reduced for miniaturization

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent develops a composite resin system that combines multiple recurring units with different functional properties. This composite structure provides the necessary balance between sensitivity and precision required for miniaturized patterns, enabling further scaling while maintaining pattern 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 resist composition achieves high resolution and improved pattern quality with minimized line edge roughness and enhanced rectangularity, making it suitable for precise micropatterning in semiconductor manufacturing.

Implementation Method 1

a compound (B) capable of generating an acid in response to actinic light or radiation

Methodology Applied

Scientific EffectPhotoacid generation: Photodissociation

Implementation Method 2

a resin component (A) which becomes soluble in an alkaline developer under the action of an acid

Methodology Applied

Scientific EffectAcid-catalyzed deprotection: Chemical Bonding

Data Source

PatentUS7618765B2Positive resist composition and patterning process

Publication Date: 2009.11.17 SHIN ETSU CHEMICAL CO LTD

AI summary

A positive resist composition comprises (A) a resin component which becomes soluble in an alkaline developer under the action of an acid, and (B) an acid generator which is a specific sulfonium salt compound. The resin (A) is a polymer comprising tertiary alkyl protective group units having a hydrophobic tetracyclo[4.4.0.12,5.17,10]dodecane structure, di- or trihydroxyadamantyl units, and monocyclic lactone units.