EUV Light Generation System Flat-Top Beam Shaping
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Solution Overview
Problem
Current EUV light generation systems face challenges in achieving stable and uniform energy distribution for microfabrication with feature sizes below 32 nm, as the Gaussian beam intensity distribution can lead to uneven irradiation of the target material, resulting in pre-plasma jetting and diffused targets being irradiated off-axis, making it difficult to maintain consistent EUV light generation.
Innovation Solution
The system employs a pre-pulse laser beam with a region of substantial uniform beam intensity distribution across its cross-section, ensuring the droplet is irradiated uniformly, and a beam-shaping optical system adjusts the beam intensity to maintain this uniformity, even when the droplet position varies, allowing for stable irradiation of the diffused target with a main pulse laser beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a Gaussian beam intensity distribution is used for laser irradiation, then the laser beam can be easily generated and focused, but the irradiation on the target material becomes uneven, causing pre-plasma jetting and off-axis irradiation of diffused targets
Solution Approach 1:
The patent transforms the laser beam intensity distribution from a standard Gaussian profile to a flat-top (uniform) distribution by modifying the beam parameters. This is achieved through optical elements that reshape the intensity profile, ensuring uniform energy distribution across the target surface while maintaining the ease of laser generation
Solution Approach 2:
The patent introduces an intermediary optical system between the laser source and the target material. This intermediary component (such as a beam shaping optical system) modifies the Gaussian beam into a flat-top beam, acting as a mediator that converts the easily generated Gaussian beam into the uniformly distributed beam needed for precise irradiation
2Adaptability or versatility
If the droplet position varies during irradiation, then the system must accommodate position variations, but maintaining uniform beam intensity distribution across the droplet becomes difficult
Solution Approach 1:
The patent creates a universal beam intensity distribution pattern (flat-top) that remains effective across a range of droplet positions. The uniform intensity distribution ensures that regardless of small position variations, the entire droplet surface receives consistent irradiation, making the system adaptable to position variations while maintaining precision
3Manufacturing precision
If the entire diffused target is to be uniformly irradiated, then the beam intensity distribution must be controlled, but this increases the complexity of the optical system
Solution Approach 1:
The patent achieves uniform irradiation by fundamentally changing the beam intensity distribution parameter from Gaussian to flat-top. This single parameter change in the beam profile simplifies the overall approach compared to using complex multi-element optical systems, as the uniform distribution inherently covers the entire diffused target area evenly
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 stability and consistency of EUV light generation by ensuring the entire diffused target is uniformly irradiated, improving the conversion efficiency and reducing variations in EUV light output.
Implementation Method 1
a laser beam focusing optical system for focusing a laser beam from the laser apparatus in the region
Implementation Method 2
a Laser Produced Plasma (LPP) type system in which plasma is generated by irradiating a target material with a laser beam
Implementation Method 3
an extreme ultraviolet (EUV) light generation system
Implementation Method 4
an optical system for controlling a beam intensity distribution of the laser beam
Data Source
AI summary
An apparatus used with a laser apparatus may include a chamber, a target supply for supplying a target material to a region inside the chamber, a laser beam focusing optical system for focusing a laser beam from the laser apparatus in the region, and an optical system for controlling a beam intensity distribution of the laser beam.