Optical Component with Movable Beam-Guiding Elements for Vignetting Reduction
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Solution Overview
Problem
Current optical components for projection exposure apparatuses face challenges in improving imaging quality, particularly at small chief ray angles, leading to vignetting and reduced illumination efficiency.
Innovation Solution
The development of an optical component with variably positionable beam-guiding elements, guided by a mechanical device, allowing for precise positioning and orientation to ensure partial or complete overlap with a predetermined circular ring area during perpendicular projection, reducing shadowing and enhancing imaging quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If beam-guiding elements are made variably positionable to improve illumination flexibility, then adaptability of illumination settings is improved, but device complexity increases due to additional positioning mechanisms
Solution Approach 1:
The patent implements dynamically adjustable beam-guiding elements that can change their position and orientation during operation. The facet mirror assembly includes movable mirrors that can be repositioned to different angles and locations, allowing the illumination system to adapt to various illumination requirements (different numerical apertures, chief ray angles, and illumination patterns) while maintaining a relatively simple overall structure through controlled dynamic adjustment rather than multiple fixed configurations
Solution Approach 2:
The beam-guiding elements serve multiple functions simultaneously: they guide illumination beams, define numerical aperture, control chief ray angles, and create different illumination patterns. The same movable mirror assembly performs all these functions through a unified positioning mechanism, reducing the need for separate components for each function and thereby managing device complexity while achieving high adaptability
2Reliability
If beam-guiding elements are positioned to overlap with circular ring area for perpendicular illumination, then imaging quality is improved by reducing vignetting, but shadowing may increase from the positioning elements themselves
Solution Approach 1:
The patent applies local quality optimization by positioning beam-guiding elements specifically in regions where they are needed for each illumination setting. The movable mirrors are selectively placed and angled to direct light only to the required areas of the pupil plane, avoiding unnecessary shadowing in other regions. This localized positioning ensures high imaging quality in the target area while minimizing overall shadowing effects
Solution Approach 2:
The patent introduces intermediate optical elements and positioning mechanisms that allow the beam-guiding elements to be adjusted without directly blocking the optical path. The movable mirror assembly acts as an intermediary that can be positioned out of the direct beam path when not needed, or precisely positioned to guide light without creating excessive shadowing, thereby mediating between the need for light guidance and the avoidance of shadowing
3Device complexity
If fixed mirror arrangements are used for illumination, then device complexity is reduced, but adaptability of illumination settings is limited
Solution Approach 1:
The patent transitions from fixed to dynamic mirror arrangements. The facet mirror assembly includes mirrors that can be repositioned and reoriented during operation, allowing the system to adapt to different illumination requirements. This dynamic capability is achieved through a relatively simple mechanical positioning mechanism that adjusts mirror angles and positions, maintaining structural simplicity while enabling versatile illumination settings
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 improves imaging quality by minimizing vignetting and increasing the flexibility of illumination settings without increasing shadowing, thereby enhancing the overall performance of projection exposure apparatuses.
Implementation Method 1
an image of one of the beam-guiding elements in this reflection position is in each case at least partly overlapping with the predetermined circular ring area
Data Source
AI summary
An optical component for a projection exposure apparatus includes a multiplicity of variably positionable beam-guiding elements which serve as pupil facets. The optical component can be arranged in the beam path of the projection optical unit.