Modified Block Copolymers for Sub-50 nm Lithography
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Solution Overview
Problem
Conventional lithographic processes face challenges in fabricating nanostructures with feature sizes below 50 nm due to high costs and slow processing times, and existing block copolymers struggle to achieve self-assembly within acceptable timeframes with low defectivity for semiconductor device fabrication.
Innovation Solution
Modifying block copolymers by incorporating modifying monomers or polymer segments to tailor the Flory-Huggins interaction parameter (χ value), allowing for reduced equilibrium defectivity and faster self-assembly, enabling thermal annealing instead of solvent annealing and reducing solvent usage, which decreases defectivity and dimension changes during self-assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithographic processes are used to fabricate nanostructures with feature sizes below 50 nm, then manufacturing precision is improved, but cost increases significantly and processing time increases
Solution Approach 1:
The patent modifies the chemical composition parameters of block copolymers by incorporating specific monomers (such as styrene, methyl methacrylate, acrylonitrile, or vinylpyridine) in controlled ratios to adjust the Flory-Huggins interaction parameter (χ value). This parameter modification enables the block copolymer to self-assemble into ordered microdomains with precise dimensional control, achieving sub-50 nm feature sizes through chemical parameter optimization rather than conventional lithographic processing
Solution Approach 2:
The patent utilizes the self-assembly capability of block copolymers where the polymer chains automatically organize into periodic microdomains (lamellae, cylinders, or spheres) based on their inherent chemical structure and χN product. This self-organizing behavior eliminates the need for external lithographic tools, allowing the block copolymer to create its own patterns through thermodynamic driving forces, thereby achieving high manufacturing precision without the cost and time constraints of conventional lithography
2Manufacturing precision
If block copolymers are used for self-assembly lithography, then manufacturing precision is improved for sub-50 nm features, but self-assembly time increases and defectivity increases
Solution Approach 1:
The patent systematically adjusts the Flory-Huggins interaction parameter (χ value) by selecting specific monomer combinations and their ratios in the block copolymer structure. By optimizing the χ value and the product χN, the patent accelerates the self-assembly kinetics while maintaining thermodynamic equilibrium, enabling the block copolymer to reach its ordered microdomain structure within acceptable timeframes (e.g., 1-24 hours) rather than requiring extended processing periods
Solution Approach 2:
The patent introduces specific functional monomers at particular positions within the block copolymer structure to create local chemical variations that enhance self-assembly behavior. For example, incorporating vinylpyridine or acrylonitrile units at specific ratios (e.g., 1:4 to 1:20 relative to other monomers) creates localized interaction sites that promote faster microphase separation and reduce defectivity in the self-assembled structure
3Manufacturing precision
If block copolymers with high χ value are used, then microphase segregation is improved, but self-assembly time increases
Solution Approach 1:
The patent optimizes the Flory-Huggins interaction parameter (χ value) to a specific range rather than maximizing it. By carefully selecting monomer combinations (such as styrene-methyl methacrylate, styrene-acrylonitrile, or styrene-vinylpyridine pairs) and their ratios, the patent achieves sufficient microphase segregation (χN > 10) while maintaining reasonable self-assembly kinetics. This balanced parameter selection prevents excessive self-assembly time while ensuring clear microdomain formation
Solution Approach 2:
The patent employs composite block copolymer structures combining multiple monomer types within the same polymer chain (e.g., styrene blocks combined with methyl methacrylate, acrylonitrile, or vinylpyridine blocks). This composite approach allows the different monomer units to contribute differently to the χ value and self-assembly behavior, achieving both strong microphase segregation and acceptable processing speeds through synergistic material design
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 modified block copolymers achieve self-assembly within four hours with an equilibrium defectivity of less than 0.5 defects per square centimeter, providing a suitable range for semiconductor device fabrication with improved pattern fidelity and reduced line edge roughness.
Implementation Method 1
Block copolymers are known to form nano-scale microdomains by microphase segregation. In the fabrication of the block copolymer, the microdomains may rearrange into a self-assembled array by microphase segregation to achieve a thermodynamic equilibrium state
Implementation Method 2
treating the block copolymer with at least one of heat and a solvent. When cast on a substrate and treated, block copolymers form nano-scale periodic patterns
Data Source
AI summary
Methods of modifying block copolymers to enhance thermodynamic properties thereof without sacrificing material properties and methods of forming modified block copolymers having desired properties are disclosed. The modified block copolymers may be used, for example, as a mask for sublithographic patterning during various stages of semiconductor device fabrication. For example, block copolymers having desirable material properties, such as etch selectively, may be chemically modified to tailor a χ value thereof to optimize the process conditions for achieving a self-assembled state and to reduce a defectivity of the self-assembled block copolymer pattern.