Resist Composition with Polymeric Acid Generator for Lithography
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Solution Overview
Problem
Current resist compositions for high-energy beam lithography, such as ArF excimer laser, face challenges with high line edge roughness and pattern collapse during liquid immersion exposure due to water solubility of acid generators, leading to suboptimal resolution and pattern precision.
Innovation Solution
A resist composition comprising a polymer with sulfonium salt having a polymerizable unsaturated bond, (meth)acrylate with a lactone or hydroxyl group for adhesion, and (meth)acrylate with an acid labile ester, which forms a polymeric acid generator that is insoluble in water, enhancing thermal stability and resolution while reducing line edge roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional acid generators with high water solubility are used to achieve high sensitivity, then exposure sensitivity improves, but line edge roughness increases and pattern collapse occurs
Solution Approach 1:
The acid generator's solubility parameter is changed from water-soluble to water-insoluble by incorporating hydrophobic groups (such as fluorinated alkyl chains) into the polymer structure. This parameter change allows the acid generator to maintain high exposure sensitivity while preventing pattern collapse and reducing line edge roughness during liquid immersion lithography
Solution Approach 2:
The acid generator is designed as a copolymer composite containing both hydrophobic groups (for water insolubility) and acid-labile groups (for photoacidity). This composite structure combines the benefits of water resistance with the functional properties needed for high-sensitivity lithography, resolving the contradiction between sensitivity and pattern fidelity
2Use of energy by moving object
If conventional acid generators are used, then high exposure sensitivity is achieved, but pattern precision deteriorates due to pattern collapse
Solution Approach 1:
By changing the solubility parameter of the acid generator from water-soluble to water-insoluble through incorporation of hydrophobic fluorinated groups, the patent prevents pattern collapse during development, thereby maintaining high pattern precision while preserving exposure sensitivity
3Use of energy by moving object
If polymeric acid generators with water solubility are used, then high sensitivity is achieved, but thermal stability decreases leading to reduced resolution
Solution Approach 1:
The polymeric acid generator is designed as a copolymer containing hydrophobic groups (for thermal stability and water insolubility) and acid-labile groups (for photoacidity). This composite structure provides both high exposure sensitivity and improved thermal stability, resolving the contradiction between sensitivity and resolution
Solution Approach 2:
The thermal stability parameter is improved by incorporating rigid and thermally stable hydrophobic groups into the polymer backbone, which raises the glass transition temperature and reduces thermal degradation, thereby maintaining resolution while preserving sensitivity
4Measurement precision
If conventional resist compositions are used for liquid immersion lithography, then high numerical aperture is achieved, but pattern collapse occurs due to water solubility
Solution Approach 1:
The solubility parameter of the acid generator is changed from water-soluble to water-insoluble by incorporating hydrophobic fluorinated alkyl chains. This parameter change prevents pattern collapse during liquid immersion development, ensuring pattern stability while maintaining the high resolution enabled by high numerical aperture
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 high sensitivity and resolution with reduced line edge roughness, suitable for precise ultra-fine processing in ArF liquid immersion lithography, preventing pattern collapse and improving pattern precision.
Implementation Method 1
a polymeric sulfonium salt as an acid generator... used in exposure to high energy beam, preferably with a wavelength of 300 nm or 200 nm or less, especially to ArF excimer laser, F2 excimer laser, EUV, X-ray or EB
Implementation Method 2
a sulfonium salt having a polymerizable unsaturated bond... copolymerized
Data Source
AI summary
There is disclosed a resist composition which comprises, at least, a polymer in which a sulfonium salt having a polymerizable unsaturated bond, a (meth)acrylate having a lactone or a hydroxyl group as an adhesion group, and a (meth)acrylate having an ester substituted with an acid labile group are copolymerized. There can be provided a resist composition with high resolution which has high sensitivity and high resolution to high energy beam, especially to ArF excimer laser, F2 excimer laser, EUV, X-ray, EB, etc., has reduced line edge roughness, and comprises a polymeric acid generator which has insolubility in water, and sufficient thermal stability and preservation stability.