Optical Diffraction Component Stray Light Suppression
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Solution Overview
Problem
Existing optical diffraction components struggle to effectively suppress stray light with wavelengths differing slightly from the desired light, limiting their applicability in EUV projection systems.
Innovation Solution
An optical diffraction component with a three-level structure, where the extent ratio of the neutral diffraction structure level to the grating period is adjusted to achieve suppression of target wavelengths, utilizing structure depths that facilitate destructive interference of radiation components with different phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional optical diffraction component with a standard grating structure is used, then the device complexity is low, but the suppression of stray light with slightly different wavelengths is ineffective
Solution Approach 1:
The grating period is segmented into multiple diffraction structure levels (first, second, and third levels) with different structure depths. This segmentation allows different portions of the grating to contribute to suppressing different target wavelengths, achieving effective stray light suppression while maintaining a manageable structural complexity through systematic division of the suppression task.
Solution Approach 2:
Different regions of the grating structure are assigned different local properties through the multi-level design. Each diffraction structure level has a specific structure depth optimized for suppressing particular target wavelengths, creating local quality variations that enable selective suppression of stray light at different wavelengths across the spectrum.
2Object-affected harmful factors
If the extent of the neutral diffraction structure level is adjusted away from 50%, then the suppression of different target wavelengths is achieved, but the manufacturing precision requirements increase
Solution Approach 1:
The invention changes the structural parameters of the grating by introducing multiple diffraction structure levels with different structure depths (first, second, and third levels). This parameter variation allows the system to achieve suppression of multiple target wavelengths by adjusting the extent ratios and structure depths, transforming a single-parameter optimization problem into a multi-parameter solution that can address wavelength-selective suppression more effectively.
3Adaptability or versatility
If a three-level diffraction structure is implemented, then the suppression of multiple target wavelengths is achieved, but the device complexity increases
Solution Approach 1:
The multi-level diffraction structure serves multiple functions within a single integrated component. The first, second, and third diffraction structure levels collectively provide suppression capability for multiple target wavelengths, making the grating universally applicable for suppressing various stray light wavelengths. This multi-functionality is achieved through the systematic arrangement of different structure depths within one grating period, allowing a single component to perform what would otherwise require multiple separate elements.
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
The solution achieves significant suppression of stray light, with reflectivity improvements of over 10 orders of magnitude at target wavelengths, enhancing the performance of EUV collectors and illumination systems.
Implementation Method 1
An optical diffraction component with a three-level structure, where the extent ratio of the neutral diffraction structure level to the grating period is adjusted to achieve suppression of target wavelengths
Implementation Method 2
utilizing structure depths that facilitate destructive interference of radiation components with different phases
Data Source
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AI summary
The invention relates to an optical diffraction component (39) having a periodic grating structure profile. The arrangement of diffraction structures is such that a wavelength range around two different target wavelengths, which are diffracted by the grating structure profile, has radiation components having three different phases which interfere destructively with one another. Diffraction structure levels (N0, N1, N2) predetermine a topography of a grating period (P) of the grating structure profile regularly repeating along a period running direction (x). These include a neutral diffraction structure level (N0), a positive diffraction structure level (N1) raised relative to the neutral level and a negative diffraction structure level (N2) lowered relative to the neutral level. Within the grating period (P) the neutral diffraction structure level (N0) has an extent along the period running direction (x) which is less than 50% of the extent of the grating period (P). A difference between the two target wavelengths is less than 50%. The result is an optical diffraction component, the possible uses of which are expanded in particular for stray light suppression.