Spectral Purity Filter Using Tungsten-Molybdenum Alloys
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current spectral purity filters in lithographic apparatuses face challenges with short lifetime due to high heat loads and hydrogen exposure, leading to delamination and degradation, while also allowing undesirable out-of-band radiation to pass through, which affects image quality and causes heating issues.
Innovation Solution
A spectral purity filter formed from tungsten-molybdenum, molybdenum-rhenium, or tungsten-rhenium alloys with nanoparticles, such as Al2O3, HfO2, and ZrO2, which are more ductile and have a higher re-crystallization temperature, reducing delamination and maintaining transparency to EUV radiation while suppressing infrared radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional spectral purity filters (silicon-based with metal coatings) are used to block infrared radiation, then infrared suppression is achieved, but the filter lifetime is short due to delamination and degradation from high heat loads and hydrogen exposure
Solution Approach 1:
The patent applies composite materials by combining silicon substrate with specific metal coatings (molybdenum, tungsten, or their alloys) to create a spectral purity filter that simultaneously achieves infrared suppression and extended lifetime. The composite structure leverages the infrared-blocking properties of metals while using the silicon substrate to provide mechanical support and thermal management, resolving the contradiction between filtration effectiveness and component durability under high heat and hydrogen exposure conditions.
2Temperature
If the filter material is made more heat-resistant to withstand high temperatures, then thermal stability improves, but the material may become more prone to delamination and degradation when exposed to hydrogen
Solution Approach 1:
The patent applies parameter changes by selecting specific metal materials (molybdenum, tungsten, or their alloys) with controlled thicknesses and properties that optimize both heat resistance and hydrogen stability. By adjusting material parameters such as thermal conductivity, coefficients of thermal expansion, and chemical reactivity, the filter achieves high-temperature tolerance while maintaining structural integrity and resistance to delamination in hydrogen-containing environments.
3Object-affected harmful factors
If the filter is made more opaque to block out-of-band radiation, then spectral purity improves, but EUV radiation transmission may be reduced
Solution Approach 1:
The patent applies local quality by designing the filter with spatially varying properties: the metal coating thickness and composition are optimized to provide strong infrared and out-of-band radiation blocking in specific wavelength ranges, while maintaining high transmission in the EUV range. This selective filtering approach ensures that the filter is highly opaque to harmful out-of-band radiation yet remains sufficiently transparent to the desired EUV radiation for effective lithography.
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 provides a more durable spectral purity filter with increased resistance to high temperatures and hydrogen exposure, ensuring longer lifetime and improved spectral purity by effectively blocking infrared radiation while allowing EUV radiation to pass through.
Implementation Method 1
The size and spacing of the apertures may be chosen such that infrared radiation is diffracted by the apertures (and thereby suppressed), while EUV radiation is transmitted through the apertures.
Implementation Method 2
the body of material is formed from a tungsten-molybdenum alloy or a molybdenum-rhenium alloy or a tungsten-rhenium alloy
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A spectral purity filter includes a body of material, through which a plurality of apertures extend. The apertures are arranged to suppress radiation having a first wavelength and to allow at least a portion of radiation having a second wavelength to be transmitted through the apertures. The second wavelength of radiation is shorter than the first wavelength of radiation. The body of material is formed from tungsten-molybdenum alloy or a molybdenum-rhenium alloy or a tungsten-rhenium alloy or a tungsten-molybdenum-rhenium alloy.