Resist Material Crosslinking for Edge Roughness and Stability
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Solution Overview
Problem
Conventional resist materials face issues with edge roughness and dimension variation due to insufficient crosslinking reactions, leading to poor resolution and storage stability, especially with the decomposition of acetal structures by strong acids generated during exposure.
Innovation Solution
A resist material comprising a polymer with hydroxyl or carboxy groups, a vinyl ether crosslinking agent, and a quencher that suppresses acid diffusion, allowing for controlled crosslinking and improved molecular weight management, enhancing resolution and storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If crosslinking reaction is performed to increase molecular weight and improve pattern strength, then pattern strength is improved, but crosslinking structures are easily decomposed by acid diffusion from exposed to unexposed parts
Solution Approach 1:
The patent changes the chemical parameter of the crosslinking structure by introducing acid-labile groups (acetal, orthoester, carbamate, carbonylamine, or oxime bonds) that selectively decompose upon acid exposure. This allows the crosslinking structure to maintain stability during storage and processing while enabling controlled decomposition in exposed regions during development, resolving the contradiction between maintaining crosslinking stability and enabling acid-responsive decomposition.
2Manufacturing precision
If molecular weight of base polymers is decreased to reduce dissolution unit size for LER reduction, then LER is reduced, but pattern collapse occurs due to lowered strength
Solution Approach 1:
The patent applies preliminary crosslinking to polymer chains before exposure, forming a stable network structure that provides mechanical strength even when using low molecular weight polymers. This preliminary crosslinking prevents pattern collapse during processing while maintaining small dissolution units for reduced LER, as the crosslinked structure remains intact until selective acid decomposition occurs in exposed regions.
Solution Approach 2:
The patent creates a composite structure combining low molecular weight polymers with crosslinking agents to form a crosslinked network. This composite approach allows the system to benefit from both the small dissolution units of low molecular weight polymers (reducing LER) and the mechanical strength provided by the crosslinked network (preventing pattern collapse).
3Quantity of substance
If crosslinking agent and polymer are used to enable crosslinking reaction, then molecular weight can be increased, but crosslinking reaction does not proceed sufficiently in baking process and remaining monomeric components negatively affect lithography performance
Solution Approach 1:
The patent optimizes the chemical parameters of the crosslinking system by selecting crosslinking agents with functional groups that have high reactivity toward the polymer's functional groups under baking conditions. The use of acid-labile crosslinking structures ensures that the crosslinking reaction proceeds to completion during baking, leaving no remaining monomeric components that would affect lithography performance, while still achieving the desired molecular weight increase.
4Strength
If crosslinking polymer with high molecular weight is used, then pattern strength is improved, but aggregation of polymers is generated after long-term storage as resist solution causing increased defects
Solution Approach 1:
The patent segments the high molecular weight crosslinked structure into smaller, soluble precursor units that can be stored as individual polymer chains and crosslinking agents in solution. During storage, these segmented units remain separate and soluble, preventing aggregation. Upon application and baking, they self-assemble and crosslink to form the desired high molecular weight network structure, providing both storage stability and pattern strength.
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 material achieves reduced edge roughness, improved resolution, and enhanced storage stability by efficiently controlling crosslinking reactions and acid diffusion, making it suitable for fine pattern formation in photomasks and EUV lithography.
Implementation Method 1
a component (V) which is decomposed by irradiation of an active ray or a radiant ray to generate an acid
Implementation Method 2
A resist containing a compound having a vinyl ether group as a crosslinking agent forms an acetal structure by an addition reaction to a carboxy group or a hydroxyl group
Implementation Method 3
a quencher having a structure represented by the following formula (2)... which suppresses acid diffusion
Data Source
AI summary
An object of the present invention is to provide a resist material and a pattern forming method with which the edge roughness and dimension variation become small, superior resolution can be obtained, pattern shape becomes preferable after exposure, and further preferable storage stability can be obtained. A resist material including (Ia) a polymer containing a repeating unit (A) including a hydroxyl group or a carboxy group; (II) a crosslinking agent having a structure represented by the following formula (1); (III) a quencher having a structure represented by the following formula (2); (IV) an organic solvent; and (V) a component which is decomposed by irradiation of an active ray or a radiant ray to generate an acid,