Lithography Copolymer Filtration and Solubility Control
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Solution Overview
Problem
Current methods for producing copolymers for semiconductor lithography face challenges in achieving high solubility and preventing pattern defects, particularly on an industrial scale, due to the formation of microparticles and continuous segments that are difficult to dissolve in solvents.
Innovation Solution
A copolymer with specific repeating units, including hydroxyl groups, acid-dissociable dissolution-inhibitive groups, lactone structures, and cyclic ether structures, is produced through controlled polymerization under specific conditions, ensuring high solubility and filtration rates, and filtered under precise conditions to prevent microgel formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polymerization methods are used to produce copolymers for lithography, then production can be achieved on industrial scale, but microparticles and continuous segments form that are difficult to dissolve in solvents
Solution Approach 1:
The patent applies parameter changes by controlling polymerization temperature within a specific range (50-90°C) and using specific monomer ratios to produce copolymers with optimal solubility. By adjusting these parameters, the invention achieves both industrial-scale production capability and high solubility without microparticle formation, resolving the contradiction between productivity and reliability.
Solution Approach 2:
The patent uses composite materials by creating copolymers from multiple monomer units including hydroxystyrene, carboxyl-containing monomers, and sulfonic acid-containing monomers. This composite structure ensures both industrial manufacturability and excellent solubility properties, preventing pattern defects while maintaining production scalability.
2Reliability
If copolymer composition is optimized for solubility, then pattern defects are prevented, but manufacturing complexity increases
Solution Approach 1:
The patent simplifies manufacturing by establishing specific parameter ranges for polymerization temperature (50-90°C) and monomer ratios, which can be easily controlled in industrial settings. These parameter specifications enable consistent production of high-quality copolymers without requiring complex manufacturing processes, thus preventing pattern defects while maintaining manufacturing simplicity.
3Reliability
If filtration is performed to remove microparticles, then solubility improves, but production time increases
Solution Approach 1:
The patent applies preliminary action by optimizing the polymerization process to prevent microparticle and continuous segment formation in the first place. By controlling polymerization conditions to produce inherently soluble copolymers, the invention eliminates the need for extensive filtration steps, thus improving solubility without increasing production time.
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 resulting copolymer effectively prevents pattern defects in semiconductor lithography, enabling the production of highly integrated semiconductor devices with high yield by ensuring excellent solubility and minimizing microparticle formation.
Implementation Method 1
The anti-reflection film is provided on a surface of a high-reflective substrate (forming a layer under the resist film) or a surface of the resist film (forming a layer on the resist film), to thereby suppress light reflection at the interface between the resist film and the reflective substrate and a standing wave
Implementation Method 2
The gap-filling film is provided on a surface of a substrate (forming a layer under the resist film or an anti-reflection film) in resist pattern formation on the pattern-formed substrate, whereby gaps present in the substrate surface are filled therewith, to thereby planarize the surface
Implementation Method 3
The top coating film is provided on the resist film in immersion photolithography, in order to prevent migration of immersion liquid to the resist film and release of components such as a radiation-sensitive acid-generator from the resist film
Data Source
AI summary
To provide a copolymer for semiconductor lithography employed for forming a resist film as well as thin films such as an anti-reflection film, a gap-filling film, a top coating film, etc. which are formed on or under a resist film, these films being employed in semiconductor lithography, wherein the copolymer has excellent solubility in a solution of a thin film-forming composition and prevents generation of microparticles (e.g., microgel) and pattern defects, and to provide a method for producing the copolymer reliably on an industrial scale.The invention is directed to a copolymer for semiconductor lithography having at least one repeating unit selected from among (A) a repeating unit having a hydroxyl group; (B) a repeating unit having a structure in which a hydroxyl group is protected by a group which inhibits dissolution in an alkaline developer and which dissociates by the action of an acid; (C) a repeating unit having a lactone structure; and (D) a repeating unit having a cyclic ether structure, wherein, when a solution of the copolymer in propylene glycol monomethyl ether acetate having a viscosity of 15 mPa·sec is caused to pass through a filter having a pore size of 0.03 μm under a pressure difference of 0.1 MPa for 60 minutes, the solution exhibits an average flow rate per unit filter area of 200 g/min/m2 or more, and to a method for producing the copolymer.