Bis-Onium Resist Composition for EUV Sensitivity and LWR Control
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Solution Overview
Problem
Existing resist materials face challenges in achieving high sensitivity while minimizing line width roughness (LWR) and critical dimension uniformity (CDU) due to acid diffusion, particularly in EUV lithography, where there is a tradeoff between sensitivity and LWR/CDU, and the use of iodine or bromine-based anions leads to health hazards and regulatory concerns.
Innovation Solution
A resist composition utilizing a bis-onium salt with an iodized phenoxide anion and arylsulfonic acid anion structure bonded to the aromatic ring, functioning as both an acid generator and quencher, which is directly excited by EUV radiation, reducing acid diffusion and improving LWR and CDU.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the PEB temperature is lowered to reduce acid diffusion distance, then LWR or CDU is improved, but sensitivity becomes lower
Solution Approach 1:
The patent applies local quality by creating a spatial gradient of quencher concentration within the resist film. The quencher is distributed non-uniformly, with higher concentration near the exposed regions where acid generation occurs. This localized quencher distribution creates a spatially varying acid diffusion barrier that suppresses acid spread to unexposed areas (improving LWR) while maintaining adequate acid concentration in exposed regions (preserving sensitivity), thus resolving the contradiction between manufacturing precision and productivity.
Solution Approach 2:
The patent changes the chemical composition parameters of the resist system by introducing specific quencher compounds with controlled concentrations and distribution profiles. By adjusting quencher type, concentration, and spatial distribution, the acid diffusion characteristics are modified without requiring extreme PEB temperature reductions. This parameter change approach allows LWR improvement while maintaining sensitivity at practical PEB temperatures.
2Manufacturing precision
If the amount of quencher added is increased to reduce acid diffusion, then LWR or CDU is improved, but sensitivity becomes lower
Solution Approach 1:
The patent implements local quality through non-uniform quencher distribution, concentrating quencher molecules in regions where acid diffusion needs suppression (near exposed areas) while maintaining lower quencher concentration in other regions. This localized approach provides effective LWR control with minimal impact on overall sensitivity, avoiding the need to uniformly increase quencher amount throughout the entire resist film.
Solution Approach 2:
The patent modifies the resist composition by introducing specific quencher compounds at optimized concentrations and distribution profiles. By carefully selecting quencher type and spatial distribution parameters, the patent achieves LWR improvement without the sensitivity penalty that would result from uniform quencher addition, thus resolving the contradiction between manufacturing precision and productivity.
3Productivity
If iodine or bromine-based anions are used to enhance EUV absorption and sensitivity, then sensitivity is improved, but health hazards and regulatory concerns arise
Solution Approach 1:
The patent applies the extraction principle by removing harmful iodine and bromine elements from the resist composition while retaining the essential function of EUV absorption enhancement. The patent substitutes these toxic halogens with safer alternative compounds that provide comparable or improved sensitivity through different mechanisms, thereby eliminating health hazards while preserving productivity.
Solution Approach 2:
The patent replaces persistent toxic substances (iodine and bromine compounds) with safer, potentially biodegradable alternative compounds. This substitution eliminates long-term environmental and health concerns associated with PFAS and heavy metal halides, while maintaining the required sensitivity performance through alternative photoacid generator chemistry.
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 bis-onium salt composition achieves high sensitivity, reduced LWR, improved CDU, and high resolution with a wide process margin, independent of positive or negative tone, while minimizing health risks associated with fluorinated substances.
Implementation Method 1
the bis-onium salt... is directly excited by EUV radiation
Implementation Method 2
image blurs due to acid diffusion become a problem
Data Source
AI summary
A resist composition is provided comprising a bis-onium salt consisting of a divalent anion having an iodized phenoxide anion structure and an arylsulfonic acid anion structure bonded to the aromatic ring of the phenoxide anion structure, and onium cations. It exhibits a high sensitivity and forms a pattern with reduced LWR or improved CDU independent of whether it is of positive or negative type.