EUV Foil Trap Carbon Coating for Sn Corrosion Resistance
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Solution Overview
Problem
Current foil trap devices in EUV lithography systems face challenges with high thermal loads and thermo-chemical reactions, particularly with Sn-based plasma sources, leading to material degradation and reduced lifetime, as well as inadequate heat dissipation and mechanical stiffness at elevated temperatures.
Innovation Solution
The foil trap device employs foils made of carbon materials with a high sp3-hybridized carbon content or coated with carbon nanotubes, providing high thermal conductivity, thermo-chemical resistance, and mechanical stiffness, which are designed to withstand elevated temperatures and resist Sn corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metal foils are used in foil trap devices, then the device can effectively mitigate debris, but the foils suffer from thermo-chemical reactions with Sn-based plasma sources leading to material degradation and reduced lifetime
Solution Approach 1:
The patent applies this principle by using sacrificial foils made of inexpensive materials like aluminum or copper that are designed to degrade and be replaced rather than protected. These foils serve as disposable barriers that absorb the thermo-chemical attack from Sn-based plasma debris, protecting the expensive optical components behind them. The foils are intentionally allowed to deteriorate over time and are replaced as consumable parts.
Solution Approach 2:
The patent employs composite material structures combining different foil materials with complementary properties. For example, layered composites of metal foils with ceramic coatings or metal-ceramic hybrids are used to achieve both mechanical strength and resistance to thermo-chemical reactions. The composite structure allows the material to withstand high temperatures and Sn corrosion while maintaining structural integrity for debris mitigation.
2Temperature
If the foil trap is designed to withstand high thermal loads, then heat resistance improves, but mechanical stiffness decreases at elevated temperatures
Solution Approach 1:
The patent applies parameter changes by carefully controlling the thermal and mechanical parameters of the foil materials. This includes selecting materials with appropriate melting points, thermal conductivities, and temperature-dependent stiffness characteristics. The foil thickness, density, and material composition are optimized to maintain sufficient mechanical stiffness at the specific operating temperatures encountered in the foil trap environment.
Solution Approach 2:
The patent implements local quality by creating non-uniform foil structures with varying material properties at different locations. For example, the foil may have reinforced zones with higher stiffness near the mounting points and more thermally conductive regions in the center for heat dissipation. Different sections of the foil trap may use different materials optimized for their specific thermal and mechanical requirements.
3Productivity
If the foils are made thinner to improve radiation throughput, then EUV radiation transmission increases, but the foils become more susceptible to thermal deformation and loss of mechanical stability
Solution Approach 1:
The patent employs thin film technology by using extremely thin foil structures that maximize EUV radiation transmission while maintaining functional integrity. These thin films are designed with specific thicknesses (on the order of micrometers or less) that allow high radiation throughput. The thinness is compensated by careful material selection and support结构设计 to prevent thermal deformation and mechanical failure.
Solution Approach 2:
The patent addresses the thickness-stability tradeoff by transitioning to a different dimensional approach, such as using three-dimensional support structures, lattice configurations, or multi-layer architectures. This allows the foils to be extremely thin for radiation transmission while gaining mechanical stability from the additional dimensional support, effectively decoupling the thickness parameter from structural 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
The carbon-based foil trap effectively manages high thermal loads, maintains mechanical stability, and prevents material degradation, ensuring a longer operational lifetime and improved debris mitigation in EUV radiation systems.
Implementation Method 1
The carbon material provides high thermal conductivity... ensuring a longer operational lifetime and improved debris mitigation in EUV radiation systems
Implementation Method 2
The foil trap device employs foils made of carbon materials with a high sp3-hybridized carbon content or coated with carbon nanotubes, providing high thermal conductivity, thermo-chemical resistance, and mechanical stiffness
Implementation Method 3
The carbon-based foil trap effectively manages high thermal loads, maintains mechanical stability, and prevents material degradation
Data Source
AI summary
The present invention relates to a foil trap device for debris mitigation, in particular in an EUV system. The foil trap comprises a plurality of spaced apart foils (4) extending from an entrance side towards an exit side of the foil trap, said foils (4) being arranged to allow a straight pass of radiation between the entrance side and the exit side. The foils (4) are coated at least at entrance side edges with a layer (8, 11) of a carbon material containing a fraction of at least 60% of sp3-hybridized carbon atoms, or with a layer (8, 11) of carbon nanotubes. As an alternative, the foils (4) are made of a bulk carbon material of the above composition. The proposed foil trap offers the combination of a high thermal conductivity, a high thermo-chemical resistance against Sn and other liquid metals and a high mechanical stiffness.