Dual Pulse EUV Source Pellet Ionization
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Solution Overview
Problem
Current EUV radiation source technologies, particularly laser-produced plasma systems, face inefficiencies in generating high-intensity EUV radiation due to high energy requirements for ionizing pure heavy noble gas clusters and limitations in coupling laser energy into free electrons, especially for longer-wavelength radiation.
Innovation Solution
The use of EUV radiation source pellets comprising a metallic particle embedded within a heavy noble gas cluster enclosed by a noble gas shell cluster, activated by a dual laser pulse scheme where the first pulse ionizes the metallic particle and the second pulse amplifies the plasma within the heavy noble gas cluster, inducing inter-orbital electron transitions and enhancing EUV radiation emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If pure heavy noble gas clusters are used as EUV radiation source, then the source can generate EUV radiation, but the ionization threshold is high and energy requirements are high
Solution Approach 1:
Metallic particles serve as intermediary elements that facilitate plasma generation. The metallic particles are embedded within the heavy noble gas cluster and act as mediators to lower the ionization threshold and enable efficient plasma formation when irradiated by laser pulses, thereby reducing the energy requirements for ionizing the heavy noble gas cluster.
Solution Approach 2:
The invention uses composite material structure where metallic particles are embedded within heavy noble gas clusters. This composite structure combines the advantages of both components: the metallic particles provide easy ionization and plasma generation, while the heavy noble gas cluster provides the necessary mass and EUV radiation emission, achieving efficient EUV radiation generation with reduced energy requirements.
2Power
If laser energy is coupled into free electrons in heavy noble gas clusters, then plasma can be generated, but the coupling efficiency is limited especially for longer-wavelength radiation
Solution Approach 1:
Metallic particles act as intermediaries that enhance laser energy coupling. When laser radiation irradiates the metallic particles, it efficiently generates plasma and free electrons. These intermediarily generated electrons then facilitate effective energy coupling into the heavy noble gas cluster, significantly improving the overall energy coupling efficiency especially for longer-wavelength radiation.
Solution Approach 2:
The first laser pulse performs preliminary action by ionizing the metallic particles and generating initial plasma. This preliminary plasma generation creates free electrons and energetic conditions that enable the second laser pulse to efficiently couple energy into the heavy noble gas cluster, thereby improving overall energy coupling efficiency.
3Illumination intensity
If dual laser pulse scheme is used with metallic particles and heavy noble gas cluster, then EUV radiation intensity is enhanced, but the device complexity increases
Solution Approach 1:
The laser irradiation process is segmented into two distinct pulses with different functions. The first laser pulse is dedicated to ionizing metallic particles and generating initial plasma, while the second laser pulse is dedicated to amplifying the plasma and generating EUV radiation from the heavy noble gas cluster. This segmentation allows each pulse to be optimized for its specific function, enhancing overall EUV radiation intensity while maintaining manageable system complexity through functional separation.
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 approach reduces the ionization threshold and increases the efficiency of EUV radiation generation by leveraging the initial plasma from metallic particles to amplify and heat the heavy noble gas cluster, resulting in enhanced EUV radiation intensity and wavelength specificity.
Implementation Method 1
Each first laser pulse generates plasma by detaching outer orbital electrons from the at least one metal particle
Implementation Method 2
Each second laser pulse amplifies the plasma embedded in the heavy noble gas cluster triggering a laser-driven self-amplifying process in which more plasma energy induces more free electrons
Implementation Method 3
The amplified plasma induces inter-orbital electron transitions in heavy noble gas and other constitute atoms leading to emission of EUV radiation
Data Source
AI summary
An extreme ultraviolet (EUV) radiation source pellet includes at least one metal particle embedded within a heavy noble gas cluster contained within a noble gas shell cluster. The EUV radiation source assembly can be activated by a sequential irradiation of at least one first laser pulse and at least one second laser pulse. Each first laser pulse generates plasma by detaching outer orbital electrons from the at least one metal particle and releasing the electrons into the heavy noble gas cluster. Each second laser pulse amplifies the plasma embedded in the heavy noble gas cluster triggering a laser-driven self-amplifying process. The amplified plasma induces inter-orbital electron transitions in heavy noble gas and other constitute atoms leading to emission of EUV radiation. The laser pulsing units can be combined with a source pellet generation unit to form an integrated EUV source system.