Immersion Resist Composition Suppressing Elution
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Solution Overview
Problem
In immersion lithography, the elution of substances from resist films into the immersion medium leads to deterioration of resist performance, staining of lens surfaces, and reduced sensitivity, making it challenging to form ultra-fine resist patterns with excellent lithography properties.
Innovation Solution
A positive resist composition comprising a resin component with acid-dissociable dissolution inhibiting groups and an acid-generator component, including a cyclic principal chain polymer and a non-cyclic polymer with specific structural units, is used to suppress elution and enhance immersion medium resistance, allowing for the formation of high-resolution resist patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional resist compositions are used in immersion lithography, then exposure sensitivity is achieved, but substance elution occurs causing resist performance deterioration and lens staining
Solution Approach 1:
The patent modifies the chemical structure of the resin by introducing specific structural units (formulae 1-4) with unique molecular configurations that reduce elution. This includes using cyclic structures and specific side chain arrangements that enhance resistance to the immersion medium while maintaining lithographic performance
Solution Approach 2:
The resist composition uses a composite resin structure combining multiple structural units in specific ratios. The resin contains a mixture of cyclic principal chain structures and side chains with acid-dissociable groups, creating a composite material that balances etching resistance, solubility control, and elution suppression
2Manufacturing precision
If ultra-fine pattern formation is pursued, then resolution is improved, but line edge roughness and etching resistance become problematic
Solution Approach 1:
The patent applies different functional groups at different locations within the resin molecule. The principal chain contains cyclic structures for etching resistance, while side chains contain acid-dissociable groups for controlled solubility and smooth line edges. This local differentiation of functional groups resolves the contradiction between resolution and line edge quality
3Productivity
If acid-dissociable groups are used to control solubility, then lithography sensitivity is improved, but elution into immersion medium increases
Solution Approach 1:
The patent carefully controls the type and amount of acid-dissociable groups used. Specific structural units (formulae 1-4) are designed with acid-dissociable groups that have optimized dissociation characteristics, using parameters like group type, position, and concentration to achieve high sensitivity while minimizing elution
Solution Approach 2:
The cyclic principal chain structure acts as an intermediary framework that holds the acid-dissociable side chains in a configuration resistant to elution. The rigid cyclic structure provides a stable backbone that prevents excessive mobility of the acid-dissociable groups, reducing their tendency to leach into the immersion medium
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 effectively suppresses substance elution, maintains excellent lithography properties, and enables the formation of high-resolution resist patterns with improved etching resistance and reduced line edge roughness, while minimizing lens contamination.
Implementation Method 1
an acid-generator component (B) which generates acid upon exposure
Data Source
AI summary
A positive resist composition for immersion exposure including a resin component (A) which has acid dissociable, dissolution inhibiting groups and exhibits increased alkali solubility under action of acid and an acid-generator component (B) which generates acid upon exposure, the resin component (A) including a cyclic principal chain polymer (A1) and a non-cyclic principal chain polymer (A2) having a structural unit (a) derived from acrylic acid as a principal chain, and the non-cyclic principal chain polymer (A2) having a structural unit (a1) derived from an acrylate ester having an acid dissociable, dissolution inhibiting group (p1) represented by general formula (p1) shown below:wherein R1′ and R2′ each independently represents a hydrogen atom or an alkyl group of 1 to 5 carbon atoms; n represents an integer of 0 to 3; and Y represents an alkyl group of 1 to 5 carbon atoms or an aliphatic cyclic group of 5 to 16 carbon atoms.