Reflective Optical Member Coupling Portion for EUV Mirror Alignment
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Solution Overview
Problem
The existing reflective optical members in EUV exposure apparatuses suffer from reduced reflection efficiency due to large steps between mirror surfaces, leading to non-film areas where the reflective film is not properly formed, resulting in lower reflection efficiency compared to other areas.
Innovation Solution
The reflective optical member is designed with a coupling portion that protrudes from one mirror element and couples to another, allowing for precise positioning of mirror blocks to prevent direct adjacency and facilitate proper film formation across the mirror surfaces, enhancing reflection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mirror elements are arranged adjacent to each other in mirror blocks, then the optical integrator function is achieved, but large steps are formed between mirror surfaces causing non-film areas and reduced reflection efficiency
Solution Approach 1:
The mirror block is divided into a reflective portion and a coupling portion. The coupling portion is positioned lower than the reflective portion, creating a stepped structure that prevents large steps between adjacent mirror surfaces while maintaining the optical integrator function.
Solution Approach 2:
Different portions of the mirror block have different heights: the reflective portion maintains its original height for optimal reflection, while the coupling portion is positioned lower to prevent excessive step formation with adjacent mirror blocks, ensuring uniform reflective film formation.
2Productivity
If mirror elements are positioned closely to maximize optical integrator performance, then compactness is achieved, but non-film areas occur due to large steps reducing reflection efficiency
Solution Approach 1:
The mirror block is segmented into reflective and coupling portions with different heights, allowing compact arrangement of mirror blocks while preventing large steps that would cause non-film areas, thus maintaining both throughput and reflection efficiency.
3Reliability
If the coupling portion is positioned at the same level as the reflective portion, then structural simplicity is maintained, but large steps between adjacent mirror blocks reduce reflection efficiency
Solution Approach 1:
The mirror block is segmented into two functional portions at different heights: the reflective portion for optimal light reflection and the coupling portion positioned lower to prevent excessive step formation, achieving improved reflection efficiency with acceptable structural complexity.
Solution Approach 2:
The coupling portion is given a different height (lower position) than the reflective portion, creating local structural variation that prevents large steps between adjacent mirror blocks while maintaining overall structural simplicity.
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 design improves the reflection efficiency of the optical member by ensuring the reflective film is formed appropriately across the entire surface, leading to higher illumination uniformity and throughput in the exposure apparatus.
Implementation Method 1
Each mirror element has a mirror surface for reflecting incident exposure light
Data Source
AI summary
An exit-side fly-eye mirror is provided with a first mirror block having a mirror element as one of a plurality of mirror elements, and a second mirror block having a mirror element as one of the plurality of mirror elements. The first mirror block has a connecting part that protrudes from an area other than the mirror surface of the mirror element, the connecting part providing a connection to the second mirror block. With the connecting part of the first mirror block, a plurality of mirror elements that includes the mirror element of the second mirror block is positioned relative to the mirror element of the first mirror block.