EUV Mirror Substrate Channels Using Tilted Laser Ablation
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Solution Overview
Problem
Current methods for producing hollow structures in EUV mirrors with complex geometries, such as curved or angled channels, face challenges in aligning the removal front perpendicular to the incoming laser radiation, leading to material modifications and stress in the workpiece, which affects the thermal stability and precision of the mirror surfaces.
Innovation Solution
A method where the removal front is intermittently tilted at an angle between 0° and 89° with respect to the incoming radiation direction, allowing for the production of hollow structures with undercuts and curved geometries by moving the focal region along offset trajectories, reducing stress and improving thermal management in EUV mirrors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the removal front is aligned perpendicular to the incoming laser radiation, then the material removal is efficient and straightforward, but it leads to material modifications and stress in the workpiece affecting thermal stability and precision
Solution Approach 1:
The patent applies asymmetry by deliberately tilting the removal front at angles between 0° and 89° relative to the incoming laser radiation direction, deviating from the conventional perpendicular alignment. This asymmetric approach allows the laser beam to remove material while minimizing stress and material modifications in the workpiece, thereby improving the thermal stability and precision of the mirror surfaces without compromising manufacturing simplicity
Solution Approach 2:
The patent changes the parameter of removal front orientation from the conventional perpendicular (90°) alignment to tilted angles between 0° and 89°. By adjusting this angular parameter, the process achieves reduced stress and material modifications while maintaining efficient material removal, resolving the contradiction between manufacturing precision and ease of manufacture
2Reliability
If the removal front is tilted at an angle between 0° and 89° with respect to the incoming radiation direction, then stress and material modifications are reduced, but the alignment and control of the laser processing becomes more complex
Solution Approach 1:
The patent implements dynamics by enabling the removal front angle to be varied during the laser processing operation. The system can adjust the tilt angle between 0° and 89° depending on the specific processing requirements, allowing optimization of thermal stability for different regions of the workpiece while managing alignment complexity through dynamic rather than static configuration
Solution Approach 2:
The patent introduces an angular dimension to the laser processing by tilting the removal front relative to the incoming radiation direction. This adds a degree of freedom to the process, enabling control over stress and material modifications through angular adjustment, while the complexity is managed by integrating this angular control into the existing laser positioning system
3Temperature
If complex hollow structures with curved or angled channels are produced, then thermal management efficiency is improved, but the manufacturing process becomes more difficult and time-consuming
Solution Approach 1:
The patent applies curvature by producing hollow structures with curved or angled channels instead of simple straight channels. This curved geometry improves thermal management efficiency by enabling better heat distribution and fluid flow within the workpiece. The tilted removal front approach facilitates the creation of these complex curved structures while managing manufacturing complexity through controlled angular adjustment
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 enables the creation of hollow structures with reduced stress and improved thermal control, enhancing the precision and productivity of EUV mirrors by allowing for efficient temperature control and fluid flow within the mirror substrates.
Implementation Method 1
method for producing at least one hollow structure in a workpiece preferably in the form of a substrate for a mirror, in particular for a mirror configured for reflecting extreme ultraviolet (EUV) radiation, through material-removing processing with pulsed laser radiation
Data Source
AI summary
A hollow structure (28) is produced in a workpiece (25) to form a substrate for a mirror through material-removing processing with pulsed laser radiation (35). The pulsed laser radiation is focused into a focal region (39), forming a removal front (46) for the areal removal of material of the workpiece (25) by moving the focal region (39) along a movement pattern (41), and producing the hollow structure (28) by moving the removal front (46) within the workpiece (25). The removal front is not aligned perpendicular to an incoming radiation direction (Z) of the pulsed laser radiation (35) at the radiation entrance side (27) of the workpiece at least intermittently during the production. The hollow structure is produced in the form of a channel through which a fluid is able to flow.