Fluorinated Resist Composition for ArF Lithography
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Solution Overview
Problem
In ArF immersion lithography, the existing resist materials face issues with pattern profile changes and defects due to water-soluble components leaching during exposure, and insufficient water repellency leading to blob defects, especially at high scanning speeds.
Innovation Solution
A fluorinated monomer and polymer with recurring units of specific structures are used to formulate a resist composition that enhances water repellency and water slip, reducing the need for protective coatings and minimizing blob defects by modifying the resist film surface to be more hydrophilic during development.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If water-soluble components are used in resist material to improve development properties, then development speed is improved, but water-soluble components leach during exposure causing pattern profile changes and defects
Solution Approach 1:
The resist material is segmented into distinct functional layers: a water-repellent protective coating layer containing fluorinated compounds applied over the resist film, and the resist film itself containing water-soluble development components. This segmentation allows each layer to perform its specific function independently - the protective coating prevents leaching while the resist film enables fast development.
Solution Approach 2:
A fluorinated protective coating acts as an intermediary layer between the water-based immersion environment and the resist film. This intermediary prevents direct contact between water-soluble components and immersion water, blocking leaching while allowing the resist to maintain its fast development properties.
2Productivity
If resist film is made less water repellent to improve development properties, then development speed is improved, but water droplets penetrate into resist film causing defects
Solution Approach 1:
The system is segmented into two functional layers: an outer water-repellent protective coating and an inner resist film with optimized development properties. The protective coating specifically handles water repellency while the resist film focuses on development performance, eliminating the need to compromise one for the other.
Solution Approach 2:
The fluorinated protective coating serves as an intermediary barrier that blocks water droplet penetration to the resist film. This allows the resist film to be formulated with less water repellency for faster development, while the protective coating prevents harmful water penetration.
3Reliability
If protective coating is applied to prevent leaching and water penetration, then pattern stability is improved, but process complexity and cost increase
Solution Approach 1:
The protective coating and resist film are combined into an integrated system where the protective coating is applied as part of the resist processing sequence. The coating can be applied in-situ or as a integrated layer, merging the protection function with the existing resist processing workflow rather than adding completely separate steps.
Solution Approach 2:
The fluorinated protective coating performs multiple functions simultaneously: it provides water repellency to prevent droplet penetration, acts as a barrier to prevent leaching of water-soluble components, and maintains compatibility with the development process. This multi-functionality reduces the need for separate protective measures.
4Reliability
If fluorinated polymer is added to resist composition to enhance water repellency, then water repellency and water slip are improved, but transparency to radiation may be affected
Solution Approach 1:
The system segments the water repellency function into a separate protective coating layer applied over the resist film. This allows the resist film to maintain high radiation transparency for ArF immersion lithography, while the protective coating provides the necessary water repellency and water slip properties.
Solution Approach 2:
The fluorinated protective coating acts as an intermediary layer that provides water repellency without interfering with the radiation transmission to the resist film. The coating is positioned such that it protects the resist from water-related issues while maintaining the optical properties needed for high-resolution patterning.
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 composition achieves high transparency and improved development properties, reducing pattern defects and maintaining water repellency and slip properties, even at high scanning speeds, without the need for protective coatings.
Implementation Method 1
enhances water repellency and water slip
Implementation Method 2
water droplets remaining on the resist film after scanning
Implementation Method 3
water slip properties, reducing the need for protective coatings and minimizing blob defects
Implementation Method 4
high transparency to radiation with wavelength of up to 200 nm
Implementation Method 5
susceptible to hydrolysis in alkaline developer, the resist film surface after development is modified hydrophilic
Data Source
AI summary
A fluorinated monomer has formula (1) wherein R1 is H, F, methyl or trifluoromethyl, R2 is a monovalent hydrocarbon group which may have halogen or oxygen, A is a divalent hydrocarbon group, and k1 is 0, 1 or 2. A polymer derived from the fluorinated monomer may be endowed with appropriate water repellency, water slip, acid lability and hydrolysis and is useful as an additive polymer in formulating a resist composition.