EUV Light Source Wire Target Cooling
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Solution Overview
Problem
In EUV light source apparatuses for large-scale production, solid tin targets melt and generate debris when irradiated with high-power driver laser beams, leading to efficiency deterioration and heat dissipation challenges, especially at high repetition frequencies and output powers.
Innovation Solution
A wire-coated target material is used, where the wire is coated with tin and continuously supplied within a vacuum chamber, with a CO2 laser generating a laser beam that focuses on the wire to create plasma, and a wire cooling unit manages heat dissipation, reducing debris generation and maintaining efficient EUV light production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If solid tin targets are used for high conversion efficiency, then EUV light generation efficiency is improved, but debris generation increases and target stability deteriorates
Solution Approach 1:
The patent changes the physical state parameter of the tin target from solid to liquid, and controls the temperature parameter to maintain tin in liquid state during laser irradiation. This parameter change prevents melting and debris generation while maintaining high conversion efficiency for EUV light generation.
Solution Approach 2:
The patent utilizes the phase transition of tin from solid to liquid state. By maintaining tin in liquid phase through controlled heating and continuous circulation, the system avoids the melting problem of solid targets and the associated debris generation, while preserving the high conversion efficiency characteristics of tin.
2Power
If high-power driver laser beams are used for EUV generation, then EUV light output is improved, but heat dissipation difficulty increases and target melting occurs
Solution Approach 1:
The patent implements continuous circulation of liquid tin through a closed-loop system with pumping means. The liquid tin continuously flows through the laser irradiation region and is cooled by circulating cooling water, enabling sustained high-power EUV generation without target melting or excessive heat accumulation.
Solution Approach 2:
The patent introduces liquid tin as an intermediary medium between the driver laser and the vacuum chamber environment. The liquid tin absorbs laser energy to generate EUV light while its liquid state and continuous circulation enable effective heat dissipation, mediating between high-power input and thermal management requirements.
3Productivity
If continuous target supply is implemented for high repetition frequency, then productivity is improved, but device complexity increases
Solution Approach 1:
The patent replaces discrete solid targets with a continuous liquid tin circulation system. The liquid tin continuously flows through the irradiation region, enabling high repetition frequency operation without the need for rapid target replacement or complex positioning mechanisms, thus achieving continuous operation with simplified target supply.
Solution Approach 2:
The liquid tin system serves multiple functions simultaneously: it acts as the target material, the cooling medium, and the continuous supply mechanism. The circulating liquid tin automatically replenishes the irradiation region and dissipates heat, eliminating the need for separate target supply and cooling systems.
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 allows for continuous and fast supply of solid targets while effectively dissipating heat, significantly reducing debris and maintaining high EUV light generation efficiency, even at high repetition frequencies and power levels.
Implementation Method 1
a laser beam irradiates a target material to excite plasma state, and extreme ultra violet light is generated from the plasma
Implementation Method 2
the target material is excited into plasma state. From this plasma, light-components with various wavelengths including the EUV light are radiated
Implementation Method 3
a wire cooling unit and target material supplying unit ensure efficient heat dissipation
Data Source
AI summary
In an extreme ultra violet light source apparatus having a comparatively large output power for exposing, a solid target is supplied fast and continuously while heat dissipation for irradiation of a driver laser light is performed successfully. The extreme ultra violet light source apparatus includes: a chamber in which extreme ultra violet light is generated; a target material supplying unit which coats a wire with target material, a wire supplying unit which supplies the wire coated with the target material to a predetermined position within the chamber, a driver laser which applies a laser beam onto the wire coated with the target material to generate plasma; and a collector mirror which collects the extreme ultra violet light radiated from the plasma and outputting the extreme ultra violet light.