EUV Laser Source Beam Compensation for Uniform Tin-Plasma Heating
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Solution Overview
Problem
Existing EUV radiation sources face inefficiencies due to non-uniform laser beam profiles, leading to uneven energy distribution, low collimation, high divergence, and thermal effects, which affect plasma generation and overall system performance.
Innovation Solution
A laser source employing a multi-pulse technique generates pre-pulse and main-pulse laser beams, augmented by an auxiliary laser beam, to correct and compensate for non-uniform energy distribution, improving plasma heating efficiency and reducing thermal effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single laser beam is used to irradiate Sn droplets, then the device complexity is low, but the energy distribution is non-uniform causing poor plasma generation
Solution Approach 1:
The laser beam is divided into multiple separate beams (first laser beam and second laser beam) that are irradiated at different positions relative to the Sn droplet. This segmentation allows each beam to contribute to different regions of the droplet, achieving more uniform overall energy distribution and improved plasma generation while maintaining relatively simple individual beam structures.
2Power
If conventional laser beams are used, then thermal effects are present, but plasma heating efficiency is low
Solution Approach 1:
The patent employs pulsed laser beams with specific temporal structures. The first and second laser beams are delivered as pulses rather than continuous waves, allowing controlled energy deposition that enhances plasma heating efficiency while managing thermal effects through temporal separation of energy input.
3Illumination intensity
If laser beams are focused to increase intensity, then EUV radiation generation improves, but beam divergence increases
Solution Approach 1:
The patent introduces a spatial arrangement dimension by positioning the first and second laser beams at different locations relative to the Sn droplet. This multi-point spatial configuration allows the system to achieve high intensity at multiple positions simultaneously, improving overall energy deposition efficiency while managing beam divergence through the geometric arrangement of multiple focal points.
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 enhances the conversion efficiency and intensity of EUV radiation generation, increasing throughput and yield in semiconductor fabrication processes.
Implementation Method 1
A laser source for an extreme ultraviolet (EUV) radiation source may generate laser beams using a multi-pulse technique
Implementation Method 2
The EUV radiation is produced from a laser produced plasma (LPP) that is generated by exposing droplets of tin (Sn) to a carbon dioxide (CO2)-based laser
Implementation Method 3
The pre-pulse laser beam may be absorbed by the target material droplet. This transforms the target material droplet into a disc shape or a mist
Implementation Method 4
achieve greater heating efficiency in tin (Sn)-based plasma to increase conversion efficiency
Implementation Method 5
This transforms the target material droplet into a disc shape or a mist. Subsequently, the laser source provides the main-pulse laser beam with large intensity and energy toward the disc-shaped target material or target material mist
Implementation Method 6
The EUV radiation is produced from a laser produced plasma (LPP) that is generated by exposing droplets of tin (Sn) to a carbon dioxide (CO2)-based laser
Implementation Method 7
A collector, which includes a curved mirror that is configured to collect EUV radiation and to focus the EUV radiation toward an intermediate focus
Data Source
AI summary
Example implementations described herein include a laser source and associated methods of operation that can balance or reduce uneven beam profile problem and even improve plasma heating efficiency to enhance conversion efficiency and intensity for extreme ultraviolet radiation generation. The laser source described herein generates an auxiliary laser beam to augment a pre-pulse laser beam and/or a main-pulse laser beam, such that uneven beam profiles may be corrected and/or compensated. This may improve an intensity of the laser source and also improve an energy distribution from the laser source to a droplet of a target material, effective to increase an overall operating efficiency of the laser source.