EUV Light Generation Using Differing Laser Beam Diameters
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Solution Overview
Problem
Current extreme ultraviolet light generating apparatuses face challenges in achieving high conversion efficiency and beam diameter control for generating EUV light at 13 nm wavelength, particularly for micro-fabrication at 32 nm or less, as existing systems struggle to optimize the irradiation beam diameters and fluence of pre-pulse and main pulse laser beams.
Innovation Solution
The apparatus employs a target supply unit, a laser system that outputs multiple laser beams with specific beam diameters and fluences, and an optical system to control the beam diameters and timing, ensuring the second pre-pulse laser beam has a larger diameter than the main pulse laser beam, optimizing the plasma generation and EUV light production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the main pulse laser beam energy is increased to improve EUV light output, then the conversion efficiency decreases due to excessive beam diameter and energy dispersion
Solution Approach 1:
The laser irradiation process is divided into three sequential stages: first pre-pulse laser beam for target preprocessing, second pre-pulse laser beam for plasma preparation, and main pulse laser beam for EUV generation. This segmentation allows each stage to optimize its beam diameter independently, preventing energy dispersion while maintaining high conversion efficiency.
Solution Approach 2:
The first and second pre-pulse laser beams are applied before the main pulse laser beam to prepare the target and plasma in advance. This preliminary action concentrates the main pulse energy more effectively, improving conversion efficiency by reducing energy dispersion during the actual EUV generation process.
2Stability of the object's composition
If the irradiation beam diameter of the second pre-pulse laser beam is increased to improve plasma uniformity, then the beam diameter control becomes more difficult
Solution Approach 1:
Different beam diameters are assigned to different laser beams based on their specific functions: the second pre-pulse laser beam uses a larger diameter (0.5-2.0 mm) for uniform plasma preparation, while the main pulse laser beam uses a smaller diameter (0.3-1.0 mm) for concentrated EUV generation. This local quality differentiation resolves the contradiction between plasma uniformity and beam control precision.
3Loss of energy
If multiple laser beams with different parameters are used to optimize EUV generation, then the system complexity increases
Solution Approach 1:
The laser system uses three laser beams with different diameters and timing, but they all target the same material (tin or tin oxide) to achieve multiple functions: target preprocessing, plasma preparation, and EUV generation. This multi-functionality approach optimizes conversion efficiency without requiring completely separate systems for each function.
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 enhances the conversion efficiency of laser energy to EUV light energy, moderates the reduction in efficiency due to increased main pulse laser beam energy, and improves the beam diameter control, addressing the limitations of existing systems for finer micro-fabrication demands.
Implementation Method 1
an LPP (laser produced plasma) type apparatus using plasma generated by irradiating target material with a pulse laser beam
Implementation Method 2
irradiating target material with a pulse laser beam
Data Source
AI summary
An extreme ultraviolet light generating apparatus includes a target supply unit configured to output a target toward a predetermined region, a laser system configured to output a first laser beam with which the target is irradiated, a second laser beam with which the target is irradiated after being irradiated with the first laser beam, and a third laser beam with which the target is irradiated after being irradiated with the second laser beam, and an optical system configured to cause an irradiation beam diameter of the second laser beam at the target to be larger than an irradiation beam diameter of the third laser beam at the target.