Positive Resist Composition for ArF Lithography
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Solution Overview
Problem
Current micropatterning technologies using ArF excimer laser lithography face challenges in achieving high resolution and minimal line edge roughness due to poor affinity of base resins to developers, leading to issues like current leakage and transistor degradation, and existing photoacid generators lack sufficient acid strength or stability, particularly with perfluoroalkanesulfonic acids.
Innovation Solution
A positive resist composition comprising a polymer with specific recurring units and a sulfonium salt compound capable of generating an acid in response to actinic light, which improves resolution and mask fidelity while minimizing line edge roughness, and a patterning process involving heat treatment, exposure, and development.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photoacid generators capable of generating perfluoroalkanesulfonic acid are used to increase acid strength, then resolution and sensitivity are improved, but stability and environmental compatibility deteriorate due to C—F bond stability and biological accumulation
Solution Approach 1:
The patent changes the chemical parameters of the photoacid generator by using partially fluorinated alkane sulfonic acids (with reduced degree of fluorine substitution) instead of fully perfluorinated acids. This parameter change maintains sufficient acid strength for high resolution while improving stability and reducing biological accumulation, thus resolving the contradiction between resolution and stability.
2Manufacturing precision
If base resin solubility in developer is increased to reduce line edge roughness, then LER is minimized, but affinity to developer increases which may compromise pattern fidelity
Solution Approach 1:
The patent modifies the chemical parameters of the base resin by introducing specific hydrophilic groups and adjusting the molecular structure to optimize solubility in alkaline developers. This parameter change improves wetting and dissolution characteristics, reducing line edge roughness while maintaining pattern fidelity through controlled solubility enhancement.
3Manufacturing precision
If amount of photoacid generator is increased to reduce line edge roughness, then LER is reduced, but exposure dose dependency and mask fidelity are compromised
Solution Approach 1:
The patent changes the chemical parameters of the photoacid generator (using partially fluorinated alkane sulfonic acids with optimized structure) to achieve higher efficiency per unit amount. This allows reduction of the photoacid generator concentration while maintaining sufficient acid generation for low LER and preserving mask fidelity, thus resolving the contradiction.
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 good mask fidelity with minimized line edge roughness, effectively addressing the limitations of existing technologies in ArF excimer laser lithography.
Implementation Method 1
a compound (B) capable of generating an acid in response to actinic light or radiation
Implementation Method 2
a resin component (A) which becomes soluble in an alkaline developer under the action of an acid
Data Source
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. The resin (A) is a polymer comprising specific recurring units, represented by formula (1). The acid generator (B) is a specific sulfonium salt compound. When processed by lithography, the composition is improved in resolution and forms a pattern with a satisfactory mask fidelity and a minimal LER.Herein R1 is H or methyl, m is 1 or 2, and n is 1 or 2.