EUV Reflective Optical Element Hydrogen Diffusion Barrier
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Solution Overview
Problem
EUV lithography devices face challenges with contamination and delamination of reflective optical elements due to reactive hydrogen, leading to reduced reflectivity and service life, particularly in collector mirrors where hydrogen-related issues cause macroscopic blistering and delamination.
Innovation Solution
A reflective optical element with a functional layer between the substrate and reflective coating, comprising materials like ruthenium, chromium, platinum, and molybdenum, which reduces hydrogen concentration by at least a factor of 2, along with a microstructured layer and adhesion promoter layer to enhance adhesion and suppress hydrogen diffusion, thereby reducing the risk of delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective layer system is provided against reactive hydrogen on the reflective coating, then delamination is prevented, but the device complexity increases
Solution Approach 1:
A functional layer is deposited on the substrate before applying the reflective coating, creating a preventive barrier against hydrogen diffusion before the coating is exposed to reactive hydrogen during operation. This preliminary protective measure prevents delamination without requiring complex protective layer systems on top of the reflective coating.
Solution Approach 2:
The functional layer acts as an intermediary barrier between the substrate and the reflective coating, blocking hydrogen diffusion pathways. This intermediate layer mediates the interaction between hydrogen and the reflective coating, preventing direct contact and subsequent delamination while maintaining a relatively simple overall structure.
2Adaptability or versatility
If multiple reflective optical elements are arranged one behind the other, then the optical system functionality is improved, but the overall reflectivity decreases due to cumulative contamination
Solution Approach 1:
The functional layer is applied in advance to all reflective optical elements before they are installed in the multi-element optical system. This preliminary protection ensures that each element maintains high reflectivity throughout operation, preventing the cumulative reflectivity loss that would occur with multiple contaminated elements arranged in sequence.
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 effectively reduces the likelihood of reflective coating delamination and cracking, maintaining high reflectivity and extending the service life of EUV lithography components by acting as a diffusion barrier and improving adhesion, while also filtering out undesirable radiation to prevent damage from infrared and ultraviolet exposure.
Implementation Method 1
a functional layer is arranged between the reflective coating and the substrate, by means of which the concentration of hydrogen in atomic % on the side of the substrate facing the reflective coating is reduced by at least a factor of 2
Implementation Method 2
an adhesion promoter layer is arranged on the substrate
Implementation Method 3
a reflective coating for reflecting radiation in the wavelength range from 5 nm to 20 nm
Implementation Method 4
a microstructured layer is arranged between the reflective coating and the substrate
Data Source
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AI summary
The aim of the invention is to prevent a reflective coating from delaminating from the substrate under the effect of reactive hydrogen. This is achieved in that a reflective optical element (50) for EUV lithography is provided, having a substrate (51) and a reflective coating (54) for reflecting radiation in the wavelength range of 5 nm to 20 nm, wherein a functional layer (60) is arranged between the reflective coating (54) and the substrate (51), and the concentration of hydrogen in atomic percentage on the substrate face facing the reflective coating is reduced by at least one factor (2) by means of the functional layer.