Laser Unit Stable Resonator Spectral Width Control
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Solution Overview
Problem
Current semiconductor exposure apparatuses face challenges with color aberration due to wide spectral line widths of KrF and ArF excimer laser units, which affect resolution, and laser annealing techniques require improved spatial coherence to achieve uniform crystallization of amorphous films.
Innovation Solution
A laser unit design featuring a stable resonator configuration with specific G parameter relationships and a spatial coherence adjuster to narrow spectral width and enhance spatial coherence, allowing for improved beam uniformity and reduced interference fringes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a gas laser unit (KrF or ArF excimer laser) is used as the exposure light source, then ultraviolet light with short wavelength (248 nm or 193.4 nm) can be outputted, but the spectral line width becomes wide (350-400 pm), causing color aberration and decreasing resolution
Solution Approach 1:
The patent divides the laser beam into multiple beams by a beam splitting optical system, where each beam passes through a separate beam processing optical system. This segmentation allows independent spectral width control for each beam, enabling the overall system to achieve narrow effective spectral width while maintaining the short wavelength advantage of excimer lasers.
Solution Approach 2:
The patent introduces a beam splitting optical system and multiple beam processing optical systems as intermediaries between the excimer laser source and the projection lens. These intermediary systems process individual beams to narrow their spectral widths before recombination, thereby reducing color aberration without sacrificing the short wavelength benefit.
2Ease of manufacture
If laser light in free oscillation is used for laser annealing, then the process is simple, but the spatial coherence is insufficient, resulting in non-uniform crystallization of amorphous films
Solution Approach 1:
The patent transforms the static free oscillation laser beam into a dynamic structured beam by introducing spatial light modulators and beam processing optical systems. These components dynamically adjust the beam profile to achieve desired spatial coherence and uniformity while maintaining process feasibility.
Solution Approach 2:
The patent changes the spatial distribution parameters of the laser beam by using beam splitting and processing optical systems. By adjusting parameters such as beam width, intensity distribution, and spatial coherence independently for each beam, the system achieves uniform crystallization while keeping the overall process relatively simple.
3Manufacturing precision
If a line narrow module is added to the laser resonator to narrow the spectral width, then color aberration is reduced, but the device complexity increases
Solution Approach 1:
Instead of adding a single complex line narrow module to the resonator, the patent segments the laser beam into multiple beams and processes each beam separately through beam processing optical systems. This segmentation distributes the spectral narrowing function across multiple simpler components rather than requiring one complex resonator modification.
Solution Approach 2:
The patent extracts the spectral narrowing function from the laser resonator itself and implements it externally through beam processing optical systems. This extraction allows the resonator to remain relatively simple while achieving spectral width control through external beam processing.
4Manufacturing precision
If multiple beam processing optical systems are used to narrow spectral width and improve spatial coherence, then resolution and uniformity are improved, but the device complexity and cost increase
Solution Approach 1:
The patent designs beam processing optical systems that perform multiple functions simultaneously: spectral width narrowing, spatial coherence improvement, and beam profile control. By making each optical system multi-functional, the patent reduces the need for separate components for each function, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent combines multiple beam processing functions into integrated optical systems that process multiple beams simultaneously. By merging functions and processing beams in parallel, the system achieves high resolution and uniformity without a proportional increase in overall device complexity.
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
The solution effectively reduces color aberration and enhances spatial coherence, leading to improved resolution in semiconductor exposure and uniformity in laser annealing, resulting in better performance of thin film transistors and crystals.
Implementation Method 1
an optical resonator including a first optical member and a second optical member, and configured to amplify laser light generated between the discharge electrodes and output amplified laser light
Implementation Method 2
the optical resonator satisfying the following expression to configure a stable resonator in the second direction: 0<G1·G2<1
Data Source
AI summary
A laser unit may include a laser chamber including a pair of discharge electrodes that are opposed to each other in a first direction with an electrode gap interposed in between and are configured to provide a discharge width in a second direction, orthogonal to the first direction, smaller than the electrode gap; and an optical resonator including a first optical member and a second optical member that are opposed to each other in a third direction orthogonal to both the first direction and the second direction with the discharge electrodes interposed in between, and configured to amplify laser light generated between the discharge electrodes and output amplified laser light, the optical resonator satisfying the following expression to configure a stable resonator in the second direction:0<G1·G2<1where G1 is a G parameter of the first optical member, and G2 is a G parameter of the second optical member.