Curved Optical Surface Thermal Conditioning in EUV Lithography
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Solution Overview
Problem
Lithographic apparatuses using EUV radiation face challenges with unwanted IR and DUV radiation causing heat damage and deformation issues due to non-uniform thermal gradients in optical elements, which can lead to image distortion and chuck positioning errors.
Innovation Solution
An optical element with a curved surface and heat transfer surface featuring sealed recesses forming closed channels allows fluid flow for thermal conditioning, with regions of the heat transfer surface aligned along the curved profile to maintain uniform temperature distribution, and a method involving fluid delivery and temperature control to manage thermal gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If EUV radiation is used for lithography, then resolution is improved, but unwanted IR and DUV radiation causes heat damage and deformation
Solution Approach 1:
The patent converts the harmful thermal effects of unwanted IR and DUV radiation into a beneficial controlled thermal conditioning process. Cooling channels are intentionally designed within optical elements to actively manage and remove heat, transforming the harmful thermal gradients caused by unwanted radiation into a controlled cooling system that maintains optical element temperature and prevents deformation.
2Stability of the object's composition
If cooling channels are added to optical elements, then thermal deformation is reduced, but device complexity increases
Solution Approach 1:
The patent merges the cooling function directly into the optical elements by integrating cooling channels within the optical element structure itself. This combination eliminates the need for separate external cooling systems and reduces overall device complexity while effectively managing thermal deformation.
3Manufacturing precision
If thermal conditioning is applied to curved optical surfaces, then uniform temperature is maintained, but manufacturing difficulty increases
Solution Approach 1:
The patent applies local quality by positioning cooling channels at specific locations within the optical element structure, with heat transfer surfaces strategically placed to match the curved optical surface geometry. This localized thermal conditioning approach efficiently addresses temperature distribution issues on curved surfaces while minimizing manufacturing complexity compared to uniform cooling approaches.
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 solution effectively reduces thermal deformations and maintains uniform temperature across optical surfaces, preventing image distortion and chuck positioning errors, thereby enhancing the precision and reliability of lithographic processes.
Implementation Method 1
fluid to flow therethrough for thermal conditioning of the curved optical surface
Implementation Method 2
allow fluid to flow therethrough for thermal conditioning
Data Source
AI summary
An optical element and a lithographic apparatus including the optical element. The optical element includes a first member having a curved optical surface and a heat transfer surface, and a second member that comprises at least one recess, the at least one recess sealed against the heat transfer surface to form at least one closed channel between the first member and the second member to allow fluid to flow therethrough for thermal conditioning of the curved optical surface. In an embodiment, one or more regions of the heat transfer surface exposed to the at least one closed channel are positioned along a curved profile similar to that of the curved optical surface.