EUV Optical Assembly Corrosion Detection
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Solution Overview
Problem
Microlithographic projection exposure apparatuses in the EUV range face issues with thermal expansion and deformation of mirrors due to EUV light absorption, and existing cooling solutions often lead to corrosion-related damage and leaks, complicating the detection and prevention of such issues.
Innovation Solution
An assembly with a corrosion detector system that uses non-contact inductive conductivity measurements and magnetoinductive flow measurements to detect incipient corrosion in cooling fluids, allowing for early intervention and preventing damage by identifying changes in the cooling fluid's state, such as ionization, conductivity, flow resistance, and indicator molecules, with spatially resolved detection at critical locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling channels are used to dissipate thermal loads from optical components, then thermal management is improved, but corrosion-dictated damage and leaks occur in the cooling lines and flange connections
Solution Approach 1:
The patent introduces an inert or corrosive-resistant atmosphere environment within the cooling channels by filling the space between the cooling channel and the optical component with an inert material or corrosive-resistant coating. This prevents the cooling fluid from contacting and corroding the cooling channel walls and flange connections, thereby eliminating corrosion-dictated damage and leaks while maintaining effective thermal management.
2Difficulty of detecting and measuring
If ultrasonic measurements are used for corrosion detection, then corrosion can be detected early, but layer detachments occur at optical components
Solution Approach 1:
The patent replaces the mechanical ultrasonic measurement method with a non-contact, non-mechanical detection method such as electrical conductivity measurement, magnetic field measurement, or optical measurement. This substitution allows for early corrosion detection in the cooling fluid without applying mechanical forces that could cause layer detachments at the optical components, thereby resolving the contradiction between detection capability and component integrity.
3Ease of manufacture
If the assembly is constructed from separated components, then manufacturing and assembly are simplified, but cooling fluid flows over gaps and causes corrosion-dictated leaks
Solution Approach 1:
The patent introduces an intermediary substance or structure between the separated components that prevents cooling fluid from flowing over gaps. This intermediary could be a sealant, gasket, or encapsulating material that fills the gaps between components, blocking the path of the cooling fluid and preventing corrosion-dictated leaks while maintaining the manufacturing simplicity of separated components.
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
Effectively prevents corrosion-related damage to optical systems by enabling early detection and countermeasures, ensuring the longevity and performance of EUV microlithographic projection exposure apparatuses by accurately monitoring and addressing corrosion in cooling channels and flange connections.
Implementation Method 1
non-contact inductive conductivity measurements
Implementation Method 2
magnetoinductive flow measurements
Implementation Method 3
cooling fluid such as water, for example, flows in order to carry away heat
Data Source
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AI summary
The invention relates to an assembly in an optical system, in particular of a micro- lithographic projection exposure apparatus, comprising at least one optical element, at least one cooling channel through which can flow a cooling fluid (103, 303) for cooling said optical element during the operation of the optical system, and at least one corrosion detector (110, 310) for detecting an existing or imminent corrosion on the basis of the determination of at least one measurement variable indicating a corrosion-dictated change in state of the cooling fluid (103, 303).