Degradable Neutral Layers for Block Copolymer Lithography
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Solution Overview
Problem
In block copolymer lithography, the use of surface modifying random copolymers as neutral layers complicates template formation and can damage substrates due to the need for reactive ion etching to remove organic residues, which affects the underlying substrate's properties.
Innovation Solution
Development of polymer films comprising crosslinked random copolymers with photocleavable or mild acid-cleavable junctions that can be selectively removed without damaging the substrate, allowing for the formation of self-assembled block copolymer patterns without harsh etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If surface modifying random copolymers are used as neutral layers to control domain orientation in BCPs, then domain orientation control is improved, but substrate damage occurs due to strong reactive ion etchants needed to remove organic residues
Solution Approach 1:
The patent changes the chemical composition parameters of the neutral layer by incorporating cleavable linkages (photocleavable or acid-cleavable groups) into the random copolymer structure. This allows the neutral layer to be removed under mild conditions (UV irradiation or mild acid treatment) rather than requiring strong reactive ion etching, thereby preventing substrate damage while maintaining domain orientation control during the BCP self-assembly process
Solution Approach 2:
The patent extracts the harmful organic residues problem by designing a neutral layer with cleavable linkages that can be selectively removed after serving its function. The cleavable linkages (such as benzyl ether, acetal, or orthoester groups) allow the neutral layer to be decomposed and removed under mild conditions, eliminating the need for strong etchants that damage the substrate
2Ease of manufacture
If strong reactive ion etchants are used to remove organic BCP template structures and underlying neutral layers, then template removal is achieved, but the underlying substrate is damaged
Solution Approach 1:
The patent changes the removal conditions from harsh (strong reactive ion etchants) to mild (UV irradiation or mild acid treatment) by incorporating cleavable linkages into the neutral layer structure. This allows template removal to be achieved under gentle conditions that do not damage the underlying substrate, while still effectively removing the organic BCP template structures and neutral layer
Solution Approach 2:
The patent introduces an intermediary mechanism (cleavable linkages) that mediates between the template removal requirement and substrate protection. The photocleavable or acid-cleavable groups act as intermediaries that enable selective decomposition and removal of the neutral layer and template under mild conditions, avoiding direct contact between strong etchants and the substrate
3Object-affected harmful factors
If crosslinked random copolymers with photocleavable or mild acid-cleavable junctions are used as neutral layers, then substrate damage is prevented, but the neutral layer structure complexity increases
Solution Approach 1:
The patent creates a composite neutral layer structure by combining random copolymer chains with cleavable linkage groups (such as benzyl ether, acetal, or orthoester groups) at regular intervals. This composite structure maintains the essential neutral layer functions while enabling mild removal conditions, balancing structural complexity with substrate protection capabilities
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
Enables the creation of self-assembled block copolymer patterns on substrates with minimal damage, maintaining the substrate's properties and allowing for precise pattern transfer, thus overcoming the limitations of traditional neutral layer removal methods.
Implementation Method 1
exposing said portions to radiation having wavelengths that cleave photocleavable junctions in the crosslinks, such that the random copolymer chains are uncrosslinked
Implementation Method 2
exposing said portions to a mild acid that cleaves mild acid-cleavable junctions in the crosslinks, such that the random copolymer chains are uncrosslinked
Implementation Method 3
subjecting the domain-forming block copolymer to conditions that induce the block copolymer to self-assemble into a pattern of block copolymer domains
Data Source
AI summary
Polymer films comprising crosslinked random copolymers and methods for making the films are provided. Also provided are polymer films comprising random copolymers that are covalently linked to an underlying substrate. The polymer films can be incorporated into structures in which the films are employed as surface-modifying layers for domain-forming block copolymers and the structures can be used for pattern transfer applications via block copolymer lithography. The crosslinks between the random copolymer chains in the polymer films or the links between the random copolymer chains and the substrate surface are characterized in that they can be cleaved under relatively mild conditions.