EUV Laser Amplifier Beam Quality Control
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Solution Overview
Problem
Current EUV light generation systems for semiconductor production face challenges in achieving high amplification efficiency while maintaining a low M2 factor for pulse laser beams, which is essential for microfabrication with feature sizes of 32 nm or less, due to distortion and vignetting issues in the amplification process.
Innovation Solution
The system employs a master oscillator and multiple amplifiers with a reflective optical system comprising discharge tubes and concave mirrors, carefully designed to steer and amplify the laser beam without vignetting, using relay optical systems to maintain beam quality and suppress the deterioration of the M2 factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional amplification system is used to increase laser beam energy, then the amplification efficiency improves, but the beam quality deteriorates due to distortion and vignetting
Solution Approach 1:
The amplification system is divided into multiple discharge tubes arranged in sequence, where each tube provides a segment of amplification. This segmentation allows the beam to be amplified in stages while maintaining beam quality, as each tube can be optimized for specific amplification requirements without causing excessive distortion or vignetting.
Solution Approach 2:
The discharge tubes are arranged in a folded optical path configuration rather than a simple linear arrangement. This dimensional reorganization allows the beam to traverse multiple discharge tubes while controlling the optical path length and avoiding vignetting, thereby maintaining beam quality during high-energy amplification.
2Power
If multiple discharge tubes are arranged to amplify the laser beam, then the amplification efficiency increases, but the device complexity increases
Solution Approach 1:
Each discharge tube serves multiple functions: it provides optical amplification, maintains beam quality, and contributes to the overall energy output. The standardized design of each tube module allows for scalable configuration, where adding more tubes increases amplification efficiency without proportionally increasing system complexity.
Solution Approach 2:
The discharge tubes are activated in a periodic or sequential manner along the optical path, allowing the beam to receive controlled amplification at each stage. This periodic activation pattern enables efficient energy transfer while managing the complexity of synchronizing multiple discharge events.
3Ease of operation
If the laser beam is steered through a complex optical path, then the beam can be delivered to the target position, but vignetting occurs causing beam quality deterioration
Solution Approach 1:
The optical system incorporates curved or folded optical paths using mirrors and lenses with specific curvatures to steer the beam through the multiple discharge tubes. This curved path design avoids sharp angles and narrow apertures that would cause vignetting, thereby maintaining beam quality while achieving the required beam delivery to the target position.
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 amplification efficiency of the pulse laser beam, ensuring high-energy output with minimal beam quality deterioration, thereby supporting the generation of EUV light for advanced semiconductor microfabrication.
Implementation Method 1
a plurality of discharge tubes arranged in a designed path of a seed laser beam
Implementation Method 2
an optical system arranged to steer the seed laser beam to travel along the designed path
Data Source
AI summary
An amplifier may include a plurality of discharge tubes arranged in a designed path of a seed laser beam and an optical system arranged to steer the seed laser beam to travel along the designed path.