EUV Collector Diffraction Grating for Thermal Load Reduction
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Solution Overview
Problem
Existing EUV collectors struggle to effectively separate EUV used light from extraneous light with different wavelengths without incurring excessive thermal loads on components, leading to increased demands for thermal management and potential damage.
Innovation Solution
The EUV collector design incorporates a reflective surface with a diffraction grating that diffracts EUV used light while reflecting extraneous light along a beam path with a cross section greater than twice the diameter of the EUV beam, using blaze diffraction gratings and various reflective surface configurations to enhance separation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional EUV collector design is used to collect EUV used light, then the collection efficiency is maintained, but extraneous light with different wavelengths causes excessive thermal loads on components such as extraneous light traps
Solution Approach 1:
The reflective surface is segmented into multiple reflective surface portions (first, second, third portions) with different orientations and functions. The first portion reflects extraneous light away from the collection area, the second portion diffracts EUV used light toward the collection area, and the third portion reflects additional extraneous light. This segmentation allows simultaneous management of both extraneous light and used light paths, reducing thermal loads while maintaining collection efficiency.
Solution Approach 2:
Different regions of the reflective surface are assigned different local qualities and functions. The first reflective surface portion has properties optimized for reflecting extraneous light, the second portion has diffraction grating properties for EUV used light, and the third portion handles additional extraneous light. This local differentiation enables effective separation of light paths and reduces thermal impacts on specific components.
2Loss of energy
If the beam cross section of extraneous light is reduced to minimize thermal impact, then thermal loads decrease, but the ability to separate extraneous light from used light becomes more difficult
Solution Approach 1:
The solution utilizes spatial dimensionality by directing extraneous light and used light into different spatial paths. The first reflective surface portion redirects extraneous light along a first beam path, while the second portion diffracts used light along a second beam path. By expanding the separation into multiple spatial dimensions rather than simply reducing beam size, the design achieves both thermal load reduction and effective light separation.
3Reliability
If a diffraction grating is added to separate EUV used light from extraneous light, then light separation efficiency improves, but the device complexity and manufacturing cost increase
Solution Approach 1:
The diffraction grating functionality is merged directly into the second reflective surface portion, combining the reflection and diffraction functions in a single integrated component. This merging eliminates the need for separate diffraction grating elements, reducing device complexity while maintaining effective light separation. The second reflective surface portion simultaneously serves as both a reflective surface and a diffraction grating.
4Reliability
If protective films are applied to lithography masks to prevent damage from extraneous light, then mask reliability improves, but reflection losses increase and energy efficiency decreases
Solution Approach 1:
The collector performs preliminary separation of extraneous light from used light before the light reaches the lithography mask. By using the first reflective surface portion to redirect extraneous light away from the collection area and the second portion to diffract used light, the system prevents extraneous light from reaching the mask in the first place. This preliminary action eliminates the need for protective films, maintaining both mask durability and energy efficiency.
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 reduces thermal loads on components by effectively separating EUV used light from extraneous light, allowing for improved energy efficiency and reduced reflection losses, enabling the use of lithography masks without protective films and facilitating compact collector construction.
Implementation Method 1
a diffraction grating for EUV used light, by which the EUV used light, which emanates from the source area, is diffracted toward a collection area
Implementation Method 2
The reflective surface is designed so that extraneous light with a wavelength that differs from a wavelength of the EUV used light is reflected along an extraneous light beam path
Data Source
AI summary
An EUV collector is used to collect EUV used light eminating from a source area. On a reflective surface of the collector, there is mounted a diffraction grating for the EUV used light. The EUV used light which emanates from the source area is diffracted by the diffraction grating toward a collection area. The reflective surface is designed at least partly as a planar reflective surface, as a parabolic reflective surface, as a rotationally symmetrically frustoconical reflective surface, or as a hollow-cylindrical reflective surface. A design of the reflective surface with ellipsoid reflective surface portions with first focal points, which lie in the source area, and second focal points, which are at a distance from one another and from the collection area, is also possible.