Measuring arrangement for the interferometric determination of the surface shape of a test specimen, as well as a method for manufacturing an optical element for such a measuring arrangement
The introduction of an aspherical beam-shaping surface in the interferometric setup corrects distortions, enabling accurate testing of large EUV mirrors by ensuring similar wavefronts and reducing distortion, thereby enhancing the reliability and efficiency of microlithography systems.
Patent Information
- Application Number
- DE102024209094
- Authority / Receiving Office
- DE · DE
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-09-23
- Publication Date
- 2026-03-26
AI Technical Summary
The challenge in microlithography is the accurate interferometric determination of large mirror surfaces, particularly in EUV projection lenses, where increasing the image-side numerical aperture necessitates larger mirrors, leading to manufacturing complexities and distortion issues in interferograms due to non-spherical surfaces, affecting resolution and accuracy.
A measuring arrangement with a beam-shaping surface designed as an aspherical distortion correction surface is introduced in the optical path to reduce distortion, using a reference element that splits the reference wave before reaching the test object, ensuring similar wavefronts for test and reference waves, and employing a beam-shaping surface to correct distortions in the interferometric setup.
This approach allows for accurate and reliable testing of large mirror surfaces by minimizing distortion, enabling smaller diffractive optical elements and maintaining uniform resolution across the interferometer camera, thus improving the performance of the optical system.