Fluorinated Resist Composition for EUV Lithography
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Solution Overview
Problem
Current chemically amplified resist compositions face challenges in achieving high sensitivity and controlling line width roughness (LWR) and critical dimension uniformity (CDU) in pattern formation, particularly with the diffusion of acids leading to degradation of line edge roughness (LER) and CDU during the lithography process for semiconductor fabrication.
Innovation Solution
A chemically amplified resist composition comprising a polymer with acid labile groups containing fluorinated aromatic rings, phenolic hydroxy groups, and an onium salt type quencher, along with a solvent, which enhances sensitivity, contrast, and resolution by controlling acid diffusion and improving etching resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If acetal protective groups requiring relatively small activation energy for deprotection are used to achieve high sensitivity, then resist sensitivity is improved, but acid diffusion occurs causing degradation of LER and CDU
Solution Approach 1:
The patent introduces a fluorinated aromatic ring structure at the para-position of the acid-labile protective group. This local structural modification creates electron-withdrawing effects that stabilize the cation intermediate during deprotection, enabling high sensitivity while suppressing acid diffusion to maintain pattern precision.
Solution Approach 2:
The patent modifies the chemical structure of the protective group by introducing fluorinated aromatic rings, which changes the electronic parameters (electron-withdrawing capability) and steric parameters of the group. This allows optimization of both deprotection energy (for sensitivity) and acid diffusion control (for precision).
2Productivity
If conventional acid labile groups are used to achieve high sensitivity, then deprotection occurs easily, but resolution and pattern profile deteriorate due to uncontrolled acid diffusion
Solution Approach 1:
The fluorinated aromatic ring is specifically positioned at the para-position of the protective group, creating a localized electron-withdrawing region that stabilizes the transition state. This local modification achieves both high deprotection efficiency and controlled acid diffusion for sharp pattern profiles.
3Strength
If aromatic skeletons with acidic side chains are used for KrF lithography, then etching resistance is improved, but light absorption near 200 nm prevents use in ArF lithography
Solution Approach 1:
The patent introduces fluorinated aromatic rings which have different optical properties compared to conventional aromatic groups. The fluorine substitution changes the electronic structure and light absorption characteristics, enabling compatibility with ArF lithography while maintaining etching resistance through the aromatic backbone structure.
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 sensitivity, improved LWR and CDU, and wide process margins, resulting in high contrast and excellent resolution for pattern formation, especially in EB and EUV lithography.
Implementation Method 1
Under the catalysis of an acid generated from the photoacid generator upon exposure to high-energy radiation, the protective group is deprotected
Implementation Method 2
a base polymer having on a phenol side chain an acidic functional group masked with an acid-decomposable protective group is often used in combination with a photoacid generator. Under the catalysis of an acid generated from the photoacid generator upon exposure to high-energy radiation, the protective group is deprotected
Implementation Method 3
Unless the diffusion of the generated acid is fully suppressed, however, deprotection reaction can take place even in the unexposed region of the resist film
Data Source
AI summary
A chemically amplified resist composition is provided comprising (A) a polymer P comprising repeat units having an acid labile group containing a fluorinated aromatic ring, repeat units having a phenolic hydroxy group, and repeat units adapted to generate an acid upon exposure, (B) an onium salt type quencher, and (C) a solvent. The resist composition exhibits a high sensitivity, low LWR and improved CDU when processed by photolithography.