EUV Light Generation Using Polarized Laser Beam Shaping
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Solution Overview
Problem
Current EUV light generation technologies face challenges in achieving high conversion efficiency and minimizing debris production, particularly in the laser-produced plasma type EUV light generation apparatus, where the interaction of pulsed laser beams with droplets results in inefficient absorption and increased debris due to the size and distribution of the droplets.
Innovation Solution
The proposed solution involves a dual-laser system where a pre-pulsed laser beam is used to elongate the beam spot of the first laser beam in the direction of the droplet sequence, followed by a main pulsed laser beam to irradiate the diffused target, optimizing the beam shaping and timing to enhance absorption and reduce debris, thereby improving the conversion efficiency of EUV light generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single pulsed laser beam is used to irradiate droplets for EUV light generation, then the apparatus structure is simple, but the conversion efficiency is low and debris production is high
Solution Approach 1:
The single laser irradiation process is segmented into two distinct stages: a pre-pulsed laser beam for diffusing and breaking down droplets, and a main pulsed laser beam for generating EUV light. This segmentation allows each laser beam to be optimized for its specific function, improving overall conversion efficiency while managing complexity through functional separation
Solution Approach 2:
The pre-pulsed laser beam performs preliminary action by diffusing the droplet target and breaking it down into finer particles before the main pulsed laser beam irradiates the diffused target. This preliminary processing enhances the absorption efficiency of the main laser beam and reduces debris production during EUV light generation
2Object-generated harmful factors
If a single pulsed laser beam irradiates droplets directly, then the process is simple, but debris production increases due to inefficient absorption
Solution Approach 1:
The pre-pulsed laser beam performs preliminary diffusion and breakdown of droplets into finer particles with higher absorption efficiency. This preliminary action ensures that when the main pulsed laser beam irradiates the diffused target, the absorption is maximized and debris production is minimized, directly addressing the harmful effect of debris
Solution Approach 2:
The pre-pulsed laser beam converts the potentially harmful direct irradiation of intact droplets into a beneficial process by first diffusing and breaking down the droplets. This transforms the irradiation process into one that enhances absorption efficiency and reduces harmful debris, turning a problematic direct irradiation approach into an optimized two-stage process
3Use of energy by moving object
If the beam spot is circular and symmetric, then the focusing is simple, but the absorption efficiency of elongated droplet sequences is reduced
Solution Approach 1:
The beam spot shape is changed from a symmetric circular form to an asymmetric elongated form that matches the orientation of the droplet sequence. The pre-pulsed laser beam creates an elongated beam spot in the traveling direction of the droplets, enhancing absorption efficiency by aligning the energy distribution with the droplet arrangement, while the beam shaping unit manages this asymmetry through controlled optical elements
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 improves the conversion efficiency of EUV light generation by ensuring higher absorbance of the target substance and reducing debris production, as the pre-pulsed laser beam breaks down the droplets into finer particles that are effectively irradiated by the main pulsed laser beam, leading to enhanced EUV light production.
Implementation Method 1
a pre-pulsed laser beam is used to elongate the beam spot of the first laser beam in the direction of the droplet sequence, followed by a main pulsed laser beam to irradiate the diffused target
Implementation Method 2
irradiate the target substance diffused by irradiation of the first laser beam with the second laser beam to produce plasma of the target substance and generate extreme ultraviolet light from the target substance
Implementation Method 3
generate extreme ultraviolet light with a wavelength in a range of 10 nm to 20 nm, preferably, in a range of 13 nm to 14 nm
Data Source
AI summary
An extreme ultraviolet light generation apparatus may include a droplet production device configured to produce a droplet of a target substance in a predetermined traveling direction, a first laser device configured to generate a first laser beam and irradiate the droplet with the first laser beam to diffuse the droplet, a second laser device configured to generate a second laser beam and irradiate the target substance diffused by irradiation of the first laser beam with the second laser beam to produce plasma of the diffused target substance and generate extreme ultraviolet light from the plasma of the target substance, and a beam shaping unit configured to elongate a beam spot of the first laser beam in the traveling direction of the droplet produced by the droplet production device.