Liquid Mirror EUV Lamp System for Debris Protection
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Solution Overview
Problem
Current EUV radiation sources face challenges in achieving high conversion efficiency and minimizing debris and high-energy ion contamination, which obstruct the collection of EUV light due to the lack of solid separation windows and sensitivity of optics to plasma debris.
Innovation Solution
A system utilizing a liquid metal-coated target with a rotating blade and a liquid mirror with an ellipsoidal surface to focus EUV radiation, allowing for increased collection efficiency and protection from debris, with the mirror liquid chosen for high reflectivity and thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If solid targets are used to produce EUV radiation, then EUV output is generated, but debris and high-energy ions contaminate the optics and obstruct EUV light collection
Solution Approach 1:
A gas jet (intermediary substance) is introduced between the solid target and the collection optics to capture and remove debris and ions before they reach the optics, while allowing EUV photons to pass through to the collector
Solution Approach 2:
The system separates the target region from the collection region using a gas jet boundary, creating distinct zones that prevent contamination while maintaining EUV radiation transfer
2Object-affected harmful factors
If solid separation windows are used to protect optics from plasma debris, then optics are protected, but no solid materials transmit radiation in the 1 nm to 100 nm EUV radiation region
Solution Approach 1:
The system changes the state of the protective medium from solid (which blocks EUV) to gas (which transmits EUV while still providing protection against debris through active capture mechanisms)
3Power
If laser plasma is used to produce EUV radiation, then high conversion efficiency is achieved, but high-energy ions and debris are also produced that require additional protection systems
Solution Approach 1:
The gas jet that would normally be considered a passive protective measure is actively used to capture and redirect debris and ions, converting a potential harmful byproduct into a controlled element that protects the optics while maintaining efficient EUV generation
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 system enhances EUV light collection efficiency and extends the lifetime and cost-effectiveness of EUV radiation sources by using a liquid mirror that can outperform traditional solid mirrors in high-volume manufacturing environments.
Implementation Method 1
When a high power laser pulse is incident on a material, for example, tin, highly ionised plasma is produced
Implementation Method 2
The light output of this plasma depends on the laser wavelength, energy and pulse length, the target material and the target geometry
Implementation Method 3
a liquid mirror with an ellipsoidal surface to focus EUV radiation
Implementation Method 4
a liquid mirror with an ellipsoidal surface to focus EUV radiation
Implementation Method 5
The speed of rotation of said mirror is chosen to balance centrifugal and surface wetting forces to ensure a uniform coating of said liquid
Implementation Method 6
A gas jet is introduced to a plasma source to capture debris and ions flying from the source
Data Source
AI summary
A system for providing extreme ultraviolet (EUV) radiation comprises a laser source arranged to produce a laser beam having a focus; and a carrier movable relative to the laser source for carrying a surface material, the surface material when carried by the carrier providing a renewable target edge. The focussed beam is arranged to impinge on the target edge to produce an EUV radiation emitting plasma. The system is cooperable with a mirror for harnessing the EUV radiation by reflecting EUV radiation impinging thereon. The mirror comprises a substantially aspheric surface and means for supplying a reflecting liquid to at least partially coat the aspheric surface, the mirror being rotatable to centrifugally confine the liquid to the aspheric surface.