Resist Underlayer Copolymer Adhesion for EUV Lithography
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Solution Overview
Problem
In advanced lithography processes like ArF immersion and EUV lithography, resist patterns face collapse due to reduced contact area with the substrate, requiring strong adhesion between the resist underlayer film and the pattern, which existing compositions, including lactone structures, fail to adequately provide.
Innovation Solution
A resist underlayer film-forming composition incorporating a copolymer with specific structural units, a crosslinking agent, and an organic acid catalyst, which chemically bonds with the resist material to enhance adhesion, using a copolymer with structural units like Formula (1) to (3) and a solvent, allowing for improved adhesion and preventing pattern collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a resist underlayer film with thin film thickness (25 nm or less) is formed, then the fine processing dimension is improved, but the adhesion to the resist pattern deteriorates causing pattern collapse
Solution Approach 1:
The patent changes the chemical composition parameters of the resist underlayer film by incorporating specific copolymers with lactone structures and reactive groups. This allows the film to maintain thin thickness (25 nm or less) while achieving strong adhesion through chemical bonding capabilities, resolving the contradiction between thin film requirement and adhesion strength
Solution Approach 2:
The patent uses composite material strategy by combining copolymer components with specific functional groups (lactone structures, reactive groups) in the resist underlayer formulation. This composite approach enables the thin film to provide both the required dimensional precision and sufficient adhesion strength through synergistic material properties
2Strength
If a lactone structure is used in the resist underlayer film-forming composition, then the adhesion to resist pattern is improved, but the pattern collapse is not fully prevented in finer resist patterns
Solution Approach 1:
The patent modifies the chemical parameters by introducing copolymers with specific reactive groups in addition to lactone structures. This enhances the adhesion mechanism beyond simple polarity effects, providing reliable pattern stability even for finer resist patterns by enabling chemical bonding interactions
Solution Approach 2:
The copolymer components act as intermediary substances that facilitate strong bonding between the resist underlayer film and the resist pattern. These intermediaries provide multiple interaction mechanisms (polar interactions, chemical bonding) that ensure both adhesion strength and pattern reliability
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 effectively improves adhesion between the resist underlayer film and the resist pattern, preventing collapse and enabling the use of ultra-thin films in EUV lithography by generating isocyanate groups that chemically bond with the resist material during heating, enhancing solvent resistance and coating properties.
Implementation Method 1
generating isocyanate groups that chemically bond with the resist material during heating
Implementation Method 2
an organic acid catalyst
Implementation Method 3
a copolymer having a structural unit in which a lactone structure and a reactive group are introduced
Data Source
AI summary
A resist underlayer film-forming composition for lithography including a copolymer having a structural unit of the following Formula (1) to Formula (3), a crosslinking agent, an organic acid catalyst, and a solvent:(wherein R1s are independently a hydrogen atom or a methyl group, R2 is a C1-3 alkylene group, A is a protective group, R3 is an organic group having a 4-membered ring to 7-membered ring lactone framework, adamantane framework, tricyclodecane framework or norbornane framework, R4 is a linear, branched or cyclic organic group having a carbon atom number of 1 to 12 in which at least one hydrogen atom is substituted with a fluoro group and which optionally has at least one hydroxy group as a substituent).