Polishing Layer for Optical Element Repair
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Solution Overview
Problem
Existing methods for repairing optical elements with coatings often cause damage to the underlying surface, making them unusable, especially in high-thermal-load applications like EUV lithography, where mirrors and collectors are expensive and require precise geometrical accuracy and low surface roughness.
Innovation Solution
The introduction of a polishing layer that can be easily processed to maintain high geometrical accuracy and low surface roughness, which can be integrated into the layer stack or applied during repair, allowing for effective removal and re-coating of damaged coatings without surface damage, and can function as both a cleaving and polishing layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If a cleaving layer is provided between the substrate and functional coating to enable simple cleaving and reuse of the substrate, then the ease of repair is improved, but the surface quality of the substrate deteriorates due to damage during coating removal
Solution Approach 1:
A polishing layer is introduced as an intermediary between the substrate and the functional coating. This polishing layer serves as a sacrificial buffer that absorbs damage during coating removal processes, preventing direct damage to the substrate surface. The polishing layer can be easily removed and replaced without affecting the underlying substrate, thus enabling repeated repair cycles while maintaining substrate integrity and surface quality.
2Manufacturing precision
If extensive surface processing is performed on the optical element to achieve high surface quality, then the surface roughness is reduced, but the geometrical accuracy of the optical element deteriorates
Solution Approach 1:
The surface treatment function is segmented and transferred to the polishing layer, which is a separate, replaceable component. The polishing layer can be independently processed to achieve high surface quality through extensive surface processing without affecting the substrate's geometrical accuracy. The polishing layer acts as a dedicated surface treatment medium that can be removed and replaced if needed, isolating the surface processing operations from the optical element's structural integrity.
3Ease of repair
If a polishing layer is provided to enable easy surface processing and maintain geometrical accuracy, then the ease of repair is improved, but the device complexity increases due to additional layers
Solution Approach 1:
The polishing layer is integrated into the existing layer stack of the optical element, merging the surface treatment function with the existing structural layers. Rather than adding a completely separate component, the polishing layer becomes part of the layered structure, combining multiple functions (structural support, surface treatment, and protective buffer) within a unified system. This integration minimizes the increase in device complexity while maintaining the benefits of easy repair and surface quality control.
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
Enables the effective and high-quality repair of optical elements by maintaining surface integrity and accuracy, allowing for the reuse of expensive optical components like EUV mirrors and collectors, reducing costs and extending their lifespan.
Implementation Method 1
a polishing layer is provided which can be processed very well and therefore allows high geometrical accuracy and low surface roughness of the optical surface of the optical element
Implementation Method 2
removal of the coating may cause damage to the surface of the optical element
Data Source
AI summary
A method for repairing optical elements having a coating, in which the coating is fully or partially removed or left on the optical element, a polishing layer being provided in the coating or a polishing layer being applied, which allows simple processing of the surface to achieve high geometrical accuracy and lower surface roughness. A new coating is applied onto the corresponding polishing layer. Also addressed are corresponding optical elements, including optical elements recycled according to the method.