Concave EUV Focusing Mirror Layout for Compact High-Brightness Sources
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Solution Overview
Problem
Conventional EUV light generation devices face limitations in producing high-brightness EUV light while maintaining a small size, which is essential for blank inspection devices, due to constraints on increasing the numerical aperture of the collector mirror, affecting focusing efficiency.
Innovation Solution
The EUV light generation device employs a focusing mirror with a concaved operating surface and a focusing lens positioned on one side of the droplet, along with a protection plate, to focus and direct EUV light efficiently, and includes a protection plate with multiple layers such as carbon nanotubes and metals to prevent damage from the laser beam, allowing for high-brightness EUV light generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the numerical aperture of the collector mirror is increased to improve EUV light collection efficiency, then the brightness of EUV light is improved, but the device size increases which is disadvantageous for blank inspection devices
Solution Approach 1:
The patent transitions from a conventional collector mirror configuration to a focusing mirror system where the laser beam, focusing lens, and focusing point are positioned on one side of the concaved operating surface. This spatial reconfiguration in a different dimensional arrangement enables high numerical aperture (0.3-0.4) without proportionally increasing device volume, achieving high EUV brightness in a compact form factor suitable for blank inspection devices
Solution Approach 2:
The patent employs a focusing mirror with a concaved operating surface (spherical or elliptical curvature) instead of a flat or simple reflective surface. This curved geometry concentrates the laser beam energy and EUV light emission at a specific focusing point, achieving high brightness through geometric focusing rather than relying solely on increasing mirror aperture size, thus maintaining compact device dimensions
2Illumination intensity
If a focusing mirror with high numerical aperture is used to improve EUV light focusing efficiency, then brightness is improved, but the operating surface becomes vulnerable to damage from the laser beam
Solution Approach 1:
The patent introduces a protection plate with a multi-layer structure (e.g., carbon nanotube layer, metal layers such as molybdenum, silicon, or tungsten) positioned between the laser beam path and the focusing mirror's operating surface. This segmented protective barrier absorbs or reflects harmful laser radiation while allowing EUV light to pass through, preventing thermal damage to the operating surface and enabling sustained high-power operation
Solution Approach 2:
The protection plate acts as an intermediary element that mediates between the high-energy laser beam and the focusing mirror's operating surface. It selectively interacts with different wavelengths: blocking the harmful infrared laser beam while being transparent to the generated EUV light, thus protecting the mirror without compromising the EUV light collection and focusing efficiency
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 configuration enables the generation of high-brightness EUV light continuously and efficiently, suitable for small-sized blank inspection devices, while preventing damage to the operating surface from the laser beam.
Implementation Method 1
A method for producing EUV light is carried out by irradiating a laser beam on a target material having a line- emitting element, in a method including the step of converting the target material into a state of plasma having at least one element having one or more emission lines in an EUV range
Implementation Method 2
irradiating a laser beam on a target material droplet
Implementation Method 3
a focusing mirror for focusing the EUV light generated through the plasma emitted by means of the irradiation of the laser beam on the droplet
Implementation Method 4
a focusing mirror for focusing the EUV light generated through the plasma emitted by means of the irradiation of the laser beam on the droplet, wherein the focusing mirror has a concaved operating surface
Implementation Method 5
a focusing lens for focusing the laser beam are located at the positions facing the operating surface of the focusing mirror
Implementation Method 6
a protection plate with multiple layers such as carbon nanotubes and metals to prevent damage from the laser beam
Implementation Method 7
a protection plate with multiple layers such as carbon nanotubes and metals
Data Source
AI summary
The present invention relates to an EUV light generation device including: a laser beam irradiated on a target material droplet; and a focusing mirror for focusing the EUV light generated through the plasma emitted by means of the irradiation of the laser beam on the droplet, wherein the focusing mirror has a concaved operating surface and a focusing point formed at a position facing the operating surface, and the laser beam and a focusing lens for focusing the laser beam are located at the positions facing the operating surface of the focusing mirror, so that the focusing point, the laser beam, and the focusing lens are located on the positions facing the operating surface, that is, on one side of the operating surface.