Fluorinated Ester Monomer for ArF Lithography Water Barrier
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Solution Overview
Problem
ArF immersion lithography faces issues with pattern profile changes and defects due to acid leaching and water penetration, requiring improved protective film materials that can be easily stripped and do not necessitate specialized coating or stripping units, while maintaining effective water barrier properties.
Innovation Solution
A novel fluorinated ester monomer with specific structural features allows for the formulation of a polymer that is transparent to radiation, alkali-soluble, and adjustable for water repellency, water slip, and surface segregation, serving as a photoresist additive or protective film material in ArF immersion lithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective film is used to prevent water penetration and acid leaching in ArF immersion lithography, then pattern profile stability is improved, but device complexity increases due to additional coating and stripping units
Solution Approach 1:
The patent combines the protective film function with the photoresist film itself by incorporating a fluorinated compound into the photoresist composition. This eliminates the need for a separate protective film layer and its associated coating and stripping units, while still providing water barrier properties and preventing acid leaching during immersion lithography
Solution Approach 2:
The fluorinated compound serves multiple functions simultaneously: it acts as a water barrier to prevent water penetration, prevents acid leaching, and maintains pattern profile stability. This multi-functionality is achieved within the photoresist film itself, eliminating the need for separate protective film units
2Reliability
If perfluoroalkyl compounds are used as protective film materials, then water barrier properties are improved, but ease of operation deteriorates due to requiring special stripping procedures
Solution Approach 1:
The protective function is merged with the photoresist film, allowing both the photoresist and protective film to be stripped simultaneously during the development process. This eliminates the need for separate stripping procedures and special stripping units
Solution Approach 2:
The fluorinated compound is incorporated into the photoresist composition, creating a homogeneous mixture where the protective agent is uniformly distributed throughout the photoresist matrix. This ensures consistent water barrier properties while maintaining compatibility with standard photoresist processing
3Manufacturing precision
If fluorocarbons are used as diluent for protective film, then film thickness control is improved, but loss of substance increases due to fluorocarbon emissions
Solution Approach 1:
The patent extracts the fluorinated protective function from a separate fluorocarbon-based protective film and incorporates it directly into the photoresist composition. This eliminates the need for fluorocarbon diluents and their associated environmental emissions, while still achieving precise film thickness control through the photoresist formulation
Solution Approach 2:
The fluorinated compound is used in small quantities within the photoresist formulation, providing the necessary protective function without requiring large amounts of fluorocarbon materials. This reduces substance loss and environmental impact while maintaining effective water barrier properties
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 polymer provides enhanced water barrier properties, reduces contact angle, and eliminates the need for a separate protective film, preventing defects and simplifying the process by being removable with the photoresist film during development.
Implementation Method 1
a polymer obtained from the monomer has transparency to radiation in a broad wavelength range from visible light to less than 200 nm and appropriate alkaline hydrolysis. The polymer permits any of water repellency, water slip and surface segregation to be adjusted
Implementation Method 2
a polymer obtained from the monomer has transparency to radiation in a broad wavelength range from visible light to less than 200 nm and appropriate alkaline hydrolysis
Implementation Method 3
The polymer permits any of water repellency, water slip and surface segregation to be adjusted by a choice of its structure
Data Source
AI summary
A fluorinated ester monomer is provided having formula (1) wherein R1 is H, CH3 or CF3, R2 and R3 are H or a monovalent hydrocarbon group, or R2 and R3 forms a hydrocarbon ring, R4 is a monovalent hydrocarbon group, and k is 0 or 1. A polymer obtained from the monomer has transparency to radiation with a wavelength of up to 200 nm and appropriate alkaline hydrolysis, is constructed such that any of water repellency, water slip and surface segregation may be adjusted by a choice of its structure, and is useful in forming ArF immersion lithography materials.