Non-planar Liquidphobic Element for Immersion Lithography
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Solution Overview
Problem
In immersion lithographic apparatuses, the movement of the substrate relative to the liquid confinement structure causes thermal issues due to gas flow and liquid sloshing, leading to optical aberrations and contamination, with existing liquidphobic materials having limited durability and convenience for application.
Innovation Solution
A lithographic apparatus with a fluid confinement structure featuring a non-planar, preformed liquidphobic element that adheres directly to the projection system's surface, forming a continuous, integral loop to minimize liquid penetration and maintain adhesion, reducing downtime and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a liquidphobic material is applied to the projection system surface, then liquid penetration is reduced and thermal load is decreased, but the material durability is limited and application convenience is reduced
Solution Approach 1:
The patent applies a liquidphobic coating material to the projection system surface that combines thermal insulation properties with liquid repellency. This composite material approach resolves the contradiction by providing both thermal load reduction and liquid penetration prevention through a single integrated coating layer, rather than requiring separate materials for each function.
Solution Approach 2:
The patent employs a coating material that can be readily reapplied to the projection system surface. Rather than requiring a permanently durable material, the system accepts periodic reapplication of the liquidphobic coating, treating it as a consumable protective layer that maintains performance through replacement rather than through indefinite durability.
2Object-affected harmful factors
If a liquidphobic material is applied to the projection system surface, then liquid penetration is reduced, but the convenience for application and maintenance is reduced
Solution Approach 1:
The patent divides the liquidphobic protection into a separate applicably coating layer that can be independently applied and removed from the projection system. This segmentation allows the liquidphobic function to be maintained through periodic reapplication rather than requiring permanent integration, improving maintenance convenience while preserving liquid penetration protection.
Solution Approach 2:
The patent prepares the projection system surface with a pre-treatment layer or primer that facilitates subsequent application of the liquidphobic coating. This preliminary surface preparation ensures proper adhesion and uniform application, reducing the complexity and time required for coating application and maintenance.
3Temperature
If gas flows through the apparatus for thermal conditioning, then thermal management is improved, but the gas stream causes immersion liquid to evaporate and creates thermal spots
Solution Approach 1:
The patent introduces a liquidphobic coating as an intermediary layer between the projection system surface and the immersion liquid. This coating acts as a barrier that prevents direct contact between the gas stream and immersion liquid, reducing evaporation caused by thermal conditioning gas flows while allowing the gas to continue providing thermal management functions.
Solution Approach 2:
The patent converts the potentially harmful effect of gas flow-induced evaporation into a beneficial thermal management system. By applying the liquidphobic coating, the system allows controlled gas flow for thermal conditioning while preventing excessive evaporation, thereby transforming the gas stream from a source of thermal spots into an effective cooling mechanism.
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 solution effectively reduces thermal loads and contamination by maintaining the integrity of the liquidphobic material, enhancing the longevity and convenience of maintaining the apparatus, thereby improving the reliability and efficiency of the lithographic process.
Implementation Method 1
The external surface of the projection system comprises a liquidphobic material which is liquidphobic with respect to the immersion liquid
Implementation Method 2
The gas stream may disadvantageously cause the immersion liquid to evaporate, thereby applying a thermal load on the liquid confinement structure and the projection system
Data Source
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AI summary
Lithographic apparatus and device manufacturing methods are disclosed. In one arrangement there is provided an immersion lithographic apparatus comprising a projection system (PS). The projection system is configured to project a patterned radiation beam through an immersion liquid onto a target portion of a substrate. An external surface of the projection system comprises a first surface (102). The first surface has a non-planar shape. An element (106) is attached to the first surface and positioned so that at least a portion of the element contacts the immersion liquid in use. The element comprises a closed loop of continuously integral material in a preformed state and conforming to the non-planar shape of the first surface.