EUV Collector with Normal and Grazing Mirror Subunits
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Solution Overview
Problem
Existing EUV radiation collectors fail to achieve a homogeneous intensity distribution in the far field, leading to increased requirements for downstream illumination optical units, such as tilting angle requirements for mirrors, which complicates beam guiding and illumination uniformity.
Innovation Solution
The collector is subdivided into normal incidence and grazing incidence mirror subunits, allowing for a targeted adaptation of the EUV radiation intensity distribution, achieving a homogeneous far field intensity distribution with reduced tilting angle requirements for downstream optical components by combining different beam paths and reflection angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-type mirror collector is used, then the structure is simple, but the far field intensity distribution is non-uniform
Solution Approach 1:
The collector is divided into multiple subunits (first subunit with normal incidence mirrors, second subunit with grazing incidence mirrors) that independently contribute to different regions of the far field. This segmentation allows each subunit to be optimized for its specific function while collectively achieving uniform intensity distribution across the entire far field.
2Illumination intensity
If downstream mirrors have high tilting angle requirements, then beam guiding becomes complex, but intensity distribution can be adjusted
Solution Approach 1:
The collector subunits pre-adjust the intensity distribution and beam angles before the light reaches downstream optical components. By performing this adjustment upstream, the downstream mirrors require smaller tilting angles and simpler beam guiding, reducing overall system complexity while maintaining intensity distribution adaptability.
3Loss of energy
If normal incidence mirrors are used, then reflection efficiency is high, but solid angle coverage is limited
Solution Approach 1:
The collector merges two different mirror types (normal incidence and grazing incidence) that have complementary characteristics. Normal incidence mirrors provide high reflection efficiency for specific beam paths, while grazing incidence mirrors extend the solid angle coverage. Together, they achieve both high overall reflection efficiency and broad angular coverage.
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 approach results in a more efficient and compact illumination system with reduced tilting angle demands, enabling better beam guiding and uniform illumination across the far field, while maintaining high EUV radiation throughput and reducing the complexity of downstream optical components.
Implementation Method 1
at least one mirror for normal incidence which transfers the EUV radiation from the radiation source to the illumination far field
Implementation Method 2
at least one mirror for grazing incidence which transfers the EUV radiation from the radiation source to the illumination far field
Data Source
AI summary
An EUV collector transfers EUV radiation from an EUV radiation source into an illumination far field. The collector has a normal mirror collector subunit including a mirror for normal incidence, and a grazing mirror collector subunit including a mirror for grazing incidence. The arrangement of the collector subunits is such that an intensity distribution of the EUV radiation over the far field results which is composed of an inner normal mirror intensity distribution, generated by reflection at least also at the normal mirror collector subunit, and of an outer grazing mirror intensity distribution, generated by reflection at least also at the grazing mirror collector subunit. The intensity distribution, at least over a section of the far field which is greater than 40% of the total far field, deviates by less than 20% from an average intensity in the section of the far field.