Hexapod Spacer Adjustment for EUV Optical Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hexapod systems for aligning optical elements in EUV projection exposure apparatuses face challenges in achieving precise and reproducible alignment, especially in high-vacuum environments, due to limitations in spacer element replacement and alignment accuracy, which affects the overall accuracy of mirror positioning and alignment.
Innovation Solution
A hexapod system with adjustable supporting structures that allow for the removal or addition of spacer elements without dismounting the optical element, utilizing monolithic articulations and high-strength materials to maintain precise alignment and reproducibility, and incorporating a set of replaceable spacer elements to adjust working lengths and compensate for thermal displacements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If spacer elements are replaced to adjust mirror alignment, then alignment precision is improved, but the optical element must be dismounted and remounted which changes alignment and reduces reproducibility
Solution Approach 1:
The supporting structure is divided into modular components: a fixed base portion and an adjustable working length portion that can be independently modified. This segmentation allows spacer elements to be changed without affecting the mounting connections, resolving the contradiction between alignment precision and reproducibility.
Solution Approach 2:
The optical element is pre-mounted to the fixed base portion of the supporting structure with high precision. This preliminary mounting action establishes a stable reference frame that remains unchanged during subsequent spacer element replacements, ensuring alignment reproducibility while allowing precision adjustment through spacer changes.
2Manufacturing precision
If the working length of supporting structures is adjusted to align optical elements, then alignment accuracy is improved, but forces are exerted on components that change alignment from target alignment
Solution Approach 1:
The supporting structure is segmented into a fixed mounting base and an adjustable working length section. This separation allows the mounting portion to remain stable and force-free while the working length portion absorbs adjustment forces through spacer element replacement, resolving the contradiction between alignment accuracy and stability.
Solution Approach 2:
The adjustable working length portion is extracted as a separate functional element from the mounting structure. By removing the adjustment function from the mounting connection, alignment accuracy can be achieved through spacer changes without exerting forces on the mounted optical element that would compromise stability.
3Adaptability or versatility
If actuators are used to adjust mirror position in high-vacuum environments, then alignment adjustability is improved, but vacuum compatibility deteriorates due to degassing from actuator materials
Solution Approach 1:
Traditional actuated mechanical adjustment systems are replaced with a passive mechanical adjustment system using replaceable spacer elements. This substitution eliminates actuators that would degas in vacuum, maintaining vacuum compatibility while preserving alignment adjustability through manual spacer replacement.
Solution Approach 2:
Spacer elements are designed as simple, replaceable components that can be manufactured without vacuum-compatible materials constraints. These 'disposable' spacers allow alignment adjustment without requiring permanent vacuum-compatible actuator mechanisms, resolving the contradiction between adjustability and vacuum compatibility.
4Device complexity
If solid-state articulations with flexural elements are used in hexapod systems, then device complexity is reduced, but working length changes when elements bend which affects alignment precision
Solution Approach 1:
The supporting structure is segmented into rigid components connected by replaceable spacer elements rather than continuous flexural elements. This segmentation maintains structural simplicity while ensuring that each segment remains rigid and dimensionally stable, preventing the working length changes that occur in bent flexural elements and preserving alignment precision.
Data Source
AI summary
A hexapod system is provided for aligning an optical element in semiconductor clean rooms or in a vacuum, particularly in an illumination device for a microlithographic EUV projection exposure apparatus. The system includes six hexapod supporting structures. Using a set of at least two replaceable spacer elements having a different extent in at least one direction, at least one of the six supporting structures can be adjusted. The latter is adapted so that a spacer element can be removed or a spacer element can be added while the coupling of the first coupling end to the carrying structure and the coupling of the second coupling end to the optical element are maintained. A method for aligning an optical element in semiconductor clean rooms or in a vacuum including using a hexapod system is provided.