EUV Multilayer Mirror Radiation Stability via Segmented Layer Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multilayer mirrors for the EUV spectral range face a challenge in achieving high radiation resistance while maintaining high reflectivity, as thick cover layers required for radiation stability significantly reduce reflectivity.
Innovation Solution
A multilayer mirror design incorporating a first periodic layer sequence with alternating materials like molybdenum and silicon, and a second periodic layer sequence with radiation-stable materials such as oxides or nitrides, distributed across multiple layers to enhance radiation resistance without compromising reflectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick cover layer is applied to protect the multilayer mirror from high radiation intensities, then radiation resistance is improved, but reflectivity is considerably reduced
Solution Approach 1:
The patent divides the cover layer into multiple thin alternating layers of different materials (e.g., molybdenum and silicon) instead of using a single thick layer. This segmentation allows each thin layer to contribute to radiation protection while maintaining the optical interference conditions necessary for high reflectivity at the design wavelength.
Solution Approach 2:
The patent uses composite multilayer structures combining materials with different properties - some materials provide radiation stability while others provide optical contrast for reflectivity. The alternating layers create a composite structure that simultaneously achieves both radiation resistance and high reflectivity through constructive interference at the target wavelength.
2Duration of action of stationary object
If a cover layer is applied to improve radiation stability, then durability under EUV radiation is enhanced, but the optical contrast is reduced leading to lower reflectivity
Solution Approach 1:
The patent applies different material properties to different layers - radiation-stable materials are used in specific layers where they provide protection without interfering with the optical function of other layers. Each layer is optimized for its specific function, creating local quality differentiation that resolves the contradiction between radiation stability and optical contrast.
Solution Approach 2:
The alternating periodic structure of different materials creates regular optical interference patterns that maintain high reflectivity at the design wavelength. The periodic repetition of radiation-stable and optically-contrast layers ensures both radiation protection and sustained optical performance over time.
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 design achieves improved radiation stability with minimal reduction in reflectivity by distributing radiation-stable materials across multiple layers, forming a reflective interference layer system that maintains high reflectivity.
Implementation Method 1
A multilayer mirror contains a generally periodic sequence of layers made up of a large number of pairs of layers... Each of the pairs of layers contains at least two layers made of different materials, which should have the greatest possible difference in their optical constants... guarantees high reflectivity due to the optical contrast of the layer materials
Implementation Method 2
Optical elements with such short wavelengths are realized by so-called multilayer mirrors... wavelengths of approximately 13 nm to 14 nm are of particular practical importance in the EUV spectral range, since the wavelength of 13.5 nm is intended for the production of semiconductor components
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a multilayer mirror (100) for the EUV spectral range, comprising - a first periodic layer sequence (10) which has a plurality of layer pairs (12), the layer pairs (12) each having one layer (1) made from a first material and one further layer (2) made from a second material, and - a second periodic layer sequence (20) arranged on the first periodic layer sequence (10) and having at least two layer pairs (34), the layer pairs (34) of the second periodic layer sequence (20) each having one layer (3) made from a third material and one further layer (4) made from a fourth material, wherein - the third material is different from the first and the second material - the third material is an oxide or nitride of a transition metal and - the fourth material is silicon.