Positive Resist Composition for ArF Lithography
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Solution Overview
Problem
Current resist compositions for ArF immersion lithography fail to achieve sufficient post-exposure delay stability, depth of focus, line width roughness, and controlled pattern profile, which are crucial for miniaturizing patterns in advanced LSI and memory devices.
Innovation Solution
A positive resist composition comprising two onium salts and a base polymer with acid labile groups, combined with an organic solvent, to enhance post-exposure delay stability, depth of focus, and line width roughness, while forming patterns with controlled footing profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional resist compositions are used for ArF immersion lithography, then manufacturing process is simple, but post-exposure delay stability is insufficient
Solution Approach 1:
The patent uses a composite polymer system combining carboxyl-containing polymer and hydroxyl-containing polymer in specific ratios (0.1-10 wt% and 90-99.9 wt% respectively). This composite structure enables synergistic effects where the carboxyl groups provide post-exposure delay stability while the hydroxyl groups contribute to solubility and pattern formation, achieving superior reliability without excessive complexity
Solution Approach 2:
The patent optimizes specific parameters including the weight ratio of carboxyl to hydroxyl groups (0.1-10:99.9), molecular weight ranges (1,000-1,000,000), and the presence of specific functional groups. These parameter adjustments transform the resist composition to achieve excellent post-exposure delay stability while maintaining manufacturability
2Manufacturing precision
If conventional resist compositions are used, then application is easy, but depth of focus is insufficient
Solution Approach 1:
The patent controls the molecular weight of polymers within specific ranges (1,000-1,000,000) and adjusts the weight percentages of functional groups to optimize depth of focus. The carboxyl-containing polymer at 0.1-10 wt% provides acid diffusion control that enhances depth of focus, while remaining compatible with standard fabrication processes
3Manufacturing precision
If conventional resist compositions are used, then process is simple, but line width roughness is high
Solution Approach 1:
The patent introduces specific functional groups (carboxyl and hydroxyl) at controlled concentrations to locally modify the resist's chemical properties. The carboxyl groups at 0.1-10 wt% provide localized acid-base interactions that suppress acid diffusion, thereby reducing line width roughness without requiring complete restructuring of the entire resist system
Solution Approach 2:
The combination of carboxyl-containing polymer and hydroxyl-containing polymer creates a composite material where each component contributes specific properties. The carboxyl groups reduce line width roughness through controlled acid diffusion, while the hydroxyl groups maintain overall film quality and pattern definition
4Manufacturing precision
If conventional resist compositions are used, then application is straightforward, but pattern profile control is poor
Solution Approach 1:
The patent adjusts the molecular weight, functional group concentration, and polymer ratio to control pattern profile. The carboxyl-containing polymer at optimized levels provides acid diffusion control that enables precise footing profile control, while the overall composition remains compatible with existing manufacturing processes
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 demonstrates excellent post-exposure delay stability and improved depth of focus, resulting in resist patterns with reduced line width roughness and minimal defectivity, suitable for advanced lithography processes including immersion lithography.
Implementation Method 1
a base polymer comprising recurring units having a carboxyl group (or soluble group) protected with a specific acid labile group
Implementation Method 2
the base polymer adapted to increase alkaline solubility under the action of acid
Implementation Method 3
A positive resist composition comprising two onium salts and a base polymer with acid labile groups
Data Source
AI summary
A positive resist composition is provided comprising two onium salts, a base polymer comprising acid labile group-containing recurring units, and an organic solvent. The positive resist composition forms a pattern having PED stability and improved properties including DOF, LWR, and controlled footing profile.