Immersion Lithography Surface Roughness and Contact Angle Control
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Solution Overview
Problem
In immersion lithographic technologies, the existing surfaces used in lithographic apparatuses are prone to liquid evaporation and surface degradation due to continuous immersion in liquids, leading to unpredictable liquid control and reduced lyophobicity over time, which affects the critical scan speed and surface stability.
Innovation Solution
Surfaces with a surface roughness of less than or equal to 0.2 μm and a contact angle greater than or equal to 60° are used in immersion lithographic apparatuses, employing conformal or non-conformal coatings like SiOxCy, to maintain lyophobicity and reduce surface degradation, thereby enhancing the stability of the receding contact angle and extending the surface's operational lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional surfaces are used in immersion lithographic apparatuses, then the apparatus can operate initially with liquid immersion, but the surfaces are prone to liquid evaporation and surface degradation over time, leading to unpredictable liquid control and reduced lyophobicity
Solution Approach 1:
The patent applies parameter changes by precisely controlling surface roughness (Ra ≤ 0.2 μm) and contact angle (≥ 60°) to transform the surface properties. This resolves the contradiction by establishing specific parameter thresholds that prevent liquid evaporation and surface degradation, thereby maintaining both reliability and extending operational lifespan simultaneously.
Solution Approach 2:
The patent employs composite materials through conformal or non-conformal coatings (such as SiOxCy) applied to the surface. These coatings create a composite structure that combines the base surface with protective material properties, enhancing lyophobicity and resistance to degradation, thus improving reliability while extending the surface's operational lifespan.
2Loss of substance
If surfaces with high lyophobicity are used, then liquid evaporation is reduced, but maintaining high receding contact angles over time requires precise control of surface roughness and contact angle parameters
Solution Approach 1:
The patent resolves this contradiction by establishing specific parameter thresholds: surface roughness Ra ≤ 0.2 μm and contact angle ≥ 60°. These parameter specifications simultaneously achieve reduced liquid evaporation through enhanced lyophobicity while providing clear manufacturing targets for surface precision control.
Solution Approach 2:
The patent replaces mechanical surface treatment methods with conformal or non-conformal coating processes (such as SiOxCy deposition). This substitution enables more precise and consistent control of surface roughness and contact angle parameters, reducing liquid evaporation while maintaining manufacturability through advanced coating technologies.
3Productivity
If the substrate is scanned at high speed through immersion liquid, then productivity is improved, but surface degradation and loss of lyophobicity occur more rapidly, affecting critical scan speed
Solution Approach 1:
The patent applies parameter changes by optimizing surface roughness (Ra ≤ 0.2 μm) and contact angle (≥ 60°) to enhance surface stability. This resolves the contradiction by creating surfaces that maintain reliable liquid control even during high-speed scanning, thereby supporting both high productivity and sustained reliability.
Solution Approach 2:
The patent employs composite materials through protective coatings (such as SiOxCy) that provide enhanced resistance to surface degradation during high-speed operation. These composite surfaces maintain lyophobicity and liquid control stability even under the stress of rapid scanning, enabling both high productivity and reliable operation.
4Ease of operation
If surfaces are designed to maintain high contact angles, then liquid control is improved, but the receding contact angle stability degrades over time due to continuous liquid exposure
Solution Approach 1:
The patent resolves this contradiction by establishing a minimum contact angle threshold (≥ 60°) combined with controlled surface roughness (Ra ≤ 0.2 μm). These parameter specifications ensure that surfaces not only achieve good liquid control initially but also maintain receding contact angle stability over extended operational periods.
Solution Approach 2:
The patent employs conformal or non-conformal coatings (such as SiOxCy) that create a composite surface structure with enhanced temporal stability. These coating materials are specifically selected to resist degradation from continuous liquid exposure, thereby maintaining both ease of liquid control and long-term contact angle stability.
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
This approach effectively reduces liquid evaporation, maintains high receding contact angles, and increases the critical scan speed, ensuring stable and efficient operation of immersion lithographic systems by preventing surface degradation and maintaining desired contact angles over extended periods.
Implementation Method 1
the surface has a surface roughness Ra that is less than or equal to 0.2 μm and a contact angle to the immersion liquid that is greater than or equal to 60°
Data Source
AI summary
An immersion lithographic apparatus has a surface that in use is contacted by the immersion liquid and the surface has a surface roughness Ra that is less than or equal to 0.2 μm. Immersion liquid on the surface may have a contact angle of 60° or greater. The surface may be able to maintain its properties so that immersion liquid on the surface may have the contact angle for a prolonged period of immersion in the immersion liquid.