Microlithography Projection Lens Accessible Diaphragm Placement
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Solution Overview
Problem
Microlithography projection systems with aperture stops between mirrors face challenges such as vignetting, large chief ray angles, and limited space for an iris stop due to small radial distances, leading to manufacturing difficulties and reduced precision in shaping the diaphragm.
Innovation Solution
A microlithography projection system design with a diaphragm plane positioned to allow an accessible iris stop, where the diaphragm is placed at a radial distance greater than 32% of the construction length from one section of the optical path to another, enabling easier installation and adjustment of the diaphragm, and allowing for correction of telecentricity and distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the aperture stop is placed between mirrors in the optical path, then the system can control the beam path and achieve imaging, but the radial distance from the aperture stop to the optical path becomes too small, limiting space for iris stop installation and reducing manufacturing precision
Solution Approach 1:
The patent repositions the aperture stop from a location between mirrors (constrained by radial distance) to the image plane, utilizing the longitudinal dimension (optical path length) rather than the radial dimension. This dimensional shift provides sufficient installation space while maintaining imaging functionality, as the aperture stop at the image plane does not interfere with the beam path between mirrors.
Solution Approach 2:
The aperture stop is extracted from its conventional position between mirrors and relocated to the image plane. This extraction eliminates the conflict between the aperture stop and the optical path, allowing for larger radial distances and improved manufacturing precision while maintaining the system's imaging capability.
2Volume of moving object
If the aperture stop is placed close to the optical path to save space, then the system becomes more compact, but vignetting occurs and the optical path becomes obscured
Solution Approach 1:
The aperture stop is extracted from the beam path between mirrors and relocated to the image plane. This extraction eliminates the harmful effects of vignetting and optical path obscuration, as the aperture stop no longer interferes with the light path. The system maintains compactness while achieving clear optical transmission.
3Manufacturing precision
If the aperture stop is positioned to allow iris stop installation, then manufacturing precision is improved, but the system construction length increases
Solution Approach 1:
The patent utilizes the longitudinal dimension (optical path length) to position the aperture stop at the image plane, rather than increasing radial distance. This allows for sufficient installation space and improved manufacturing precision while keeping the system compact, as the aperture stop is positioned at the end of the optical path rather than expanding the radial or longitudinal construction length.
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 provides a compact, space-saving system with reduced vignetting and improved precision in diaphragm placement, enabling higher image-side numerical aperture and broader tolerance for diaphragm position and shaping precision, resulting in enhanced image quality and manufacturing efficiency.
Implementation Method 1
a first section of the optical path between a first used area (N1) and a second used area (N2) passes the diaphragm plane
Data Source
AI summary
The invention relates to a microlithography projection lens for wavelengths ≦248 nm ≦, preferably ≦193 mm, in particular EUV lithography for wavelengths ranging from 1-30 nm for imaging an object field in an object plane onto an image field in an image plane, the microlithography projection lens developed in such a manner that provision is made for an accessible diaphragm plane, into which for instance an iris diaphragm can be introduced.