EUV Optical Element Holding Device Shock Load Distribution
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Solution Overview
Problem
The challenge in microlithography is to provide an optical arrangement that supports optical elements robustly against shock loads while maintaining high imaging quality, especially in the extreme ultraviolet (EUV) range where conventional refractive systems are ineffective due to high absorbance, and existing support methods may lead to deformation and parasitic stresses.
Innovation Solution
A microlithographic optical arrangement featuring a holding device with multiple holding units distributed along a support membrane element, which decouples and equalizes stiffness among the units, allowing for uniform distribution of shock loads and reduced deformation, using a base unit with support interface units and a thin-walled support membrane element that extends along both circumferential and radial directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional three-point support is used, then the device complexity is reduced, but the reliability against shock loads deteriorates
Solution Approach 1:
The support structure is segmented into multiple holding units (at least four) distributed around the optical element, with each unit independently supporting a sector of the element. This segmentation allows the load to be distributed across multiple points rather than concentrated at three points, improving shock load resistance while maintaining manageable complexity through modular design
Solution Approach 2:
Each holding unit is designed with specific local properties including a holding element with contact surfaces adapted to the optical element's geometry, and a stiffness adapted to the local requirements. This local optimization ensures that each unit contributes effectively to shock load resistance while maintaining overall system performance
2Reliability
If the number of holding units is increased, then the reliability against shock loads is improved, but the device complexity increases
Solution Approach 1:
The holding units are designed as universal modular components that can be replicated and distributed around the optical element. Each unit performs the same fundamental function of supporting and stabilizing a sector of the optical element, allowing the system to achieve improved shock load resistance through replication rather than through increasingly complex individual components
Solution Approach 2:
The holding units are designed with adjustable and adaptable properties, including variable stiffness through spring elements or adjustable mounting mechanisms. This dynamic capability allows the system to optimize performance across different operating conditions and shock scenarios without requiring a completely different support structure for each case
3Manufacturing precision
If holding units are rigidly connected to the support structure, then the manufacturing precision is improved, but the object-generated harmful factors increase due to parasitic stresses
Solution Approach 1:
The stiffness parameter of the connection between holding units and support structure is optimized to balance positioning accuracy and stress reduction. By carefully selecting material properties, geometric parameters, and connection mechanisms (such as spring elements or compliant mounts), the system achieves sufficient rigidity for precise positioning while maintaining enough flexibility to accommodate thermal expansion and other dimensional changes without generating excessive parasitic stresses
4Reliability
If safety factors are increased, then the reliability is improved, but the device complexity and size increase
Solution Approach 1:
The support structure is divided into multiple independent holding units that collectively provide the required safety margin. Rather than oversizing a single support structure, the segmentation approach distributes the safety requirement across multiple units, each carrying a portion of the total load, thereby achieving high reliability without proportionally increasing the complexity or size of individual 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
This solution enhances the robustness and stability of optical elements against shock loads, improves imaging quality by minimizing deformation, and allows for a simpler design with fewer safety factors, enabling a larger number of holding units with uniform load distribution, thus increasing shock safety and reliability.
Implementation Method 1
a first membrane element predominantly extending along the circumferential direction and the radial direction... the holding units are supported on a first side of the first membrane element
Data Source
AI summary
An arrangement of a microlithographic imaging device, such as one that operates in the EUV range, includes a holding device for holding an optical element. The optical element includes an optical surface and defines a plane of main extension, in which the optical element defines a radial direction and a circumferential direction. The holding device includes a base unit and more than three separate holding units. The base unit includes a plurality of support interface units, which are spaced apart from one another in the circumferential direction, for connecting the holding device to a support structure. The holding units are connected to the base unit and distributed along the circumferential direction and spaced apart from one another. The holding units hold the optical element with respect to the base unit.