Laser Unit Beam Shaping for EUV Conversion Efficiency
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Solution Overview
Problem
Current extreme ultraviolet (EUV) light generating systems face challenges in achieving efficient microfabrication below 32 nm due to elliptical beam cross-sectional shapes of laser light, which reduce conversion efficiency into EUV light.
Innovation Solution
Incorporating a wavefront adjuster, such as a combination of cylindrical lenses or mirrors, to adjust the beam cross-sectional shape of the laser light to a substantially circular shape at the beam waist, improving the alignment and focus of the laser beam on the target.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser light is used to generate EUV light, then EUV light can be produced for microfabrication, but the elliptical beam cross-sectional shape reduces conversion efficiency
Solution Approach 1:
The patent applies parameter changes by modifying the beam cross-sectional shape from elliptical to substantially circular through the wavefront adjuster. This changes the geometric parameters of the laser beam to optimize its interaction with the target material, thereby improving EUV light conversion efficiency while maintaining the laser-generated plasma mechanism
Solution Approach 2:
The patent implements spheroidality by transforming the elliptical beam profile into a circular one using optical elements (cylindrical lenses or mirrors). This spherical/circular symmetry in the beam cross-section ensures uniform energy distribution on the target, maximizing plasma generation efficiency and EUV light output
2Productivity
If a wavefront adjuster is added to correct the beam shape, then conversion efficiency improves, but device complexity increases
Solution Approach 1:
The patent introduces a wavefront adjuster as an intermediary component between the laser amplifier and the target. This mediator device (comprising cylindrical lenses or mirrors) corrects the beam shape without fundamentally changing the laser generation mechanism, thereby improving efficiency while adding only a single-stage optical correction element
Solution Approach 2:
The wavefront adjuster performs preliminary action by pre-correcting the beam cross-sectional shape before the laser light reaches the target. This advance correction ensures optimal beam geometry at the point of plasma generation, maximizing conversion efficiency while keeping the correction mechanism separate and modular
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 adjustment enhances the conversion efficiency of the EUV light generation by ensuring a circular beam profile, thereby improving the microfabrication capabilities and achieving the required precision for sub-32 nm microfabrication.
Implementation Method 1
The laser amplifier may be disposed in a light path of the laser light beam outputted from the master oscillator
Implementation Method 2
The adjuster may be disposed in the light path of the laser light beam, and may be configured to adjust a beam cross-sectional shape of the laser light beam amplified by the laser amplifier to be a substantially circular shape
Implementation Method 3
The laser concentrating optical system may be configured to concentrate the laser light beam amplified by the laser amplifier into the chamber
Implementation Method 4
In the chamber, a pulsed laser light beam may be to be applied to a target to generate extreme ultraviolet light
Implementation Method 5
a pulsed laser light beam may be to be applied to a target to generate extreme ultraviolet light
Data Source
AI summary
There is provided a laser unit that may include a master oscillator, a laser amplifier, and an adjuster. The master oscillator may be configured to output a laser light beam. The laser amplifier may be disposed in a light path of the laser light beam outputted from the master oscillator. The adjuster may be disposed in the light path of the laser light beam, and may be configured to adjust a beam cross-sectional shape of the laser light beam amplified by the laser amplifier to be a substantially circular shape. The beam cross-sectional shape may be at a beam waist of the laser light beam or in the vicinity of the beam waist of the laser light beam, and may be in a plane orthogonal to a light path axis.