Long-Short Axis Reversing Module for Laser Beam Symmetry
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Solution Overview
Problem
Laser apparatuses used in excimer laser annealing for crystallizing amorphous silicon layers often experience energy distribution asymmetry due to shaking, leading to crystallization defects in polycrystalline silicon layers, which increases manufacturing costs and reduces efficiency.
Innovation Solution
A long-short axis reversing module comprising a splitter and mirrors is used to convert an incident laser beam with asymmetric energy distribution into an emitted beam with symmetric energy distribution, minimizing crystallization defects and reducing manufacturing costs by using fewer mirrors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional optical system is used without a long-short axis reversing module, then the device complexity is low, but the energy distribution of the laser beam becomes asymmetric causing crystallization defects
Solution Approach 1:
The optical system is segmented into multiple functional components: a beam splitter that divides the laser beam into first and second beams, and multiple mirrors (first mirror, second mirror, third mirror) that independently manipulate each beam. This segmentation allows precise control over energy distribution symmetry while maintaining manageable system complexity through modular design.
Solution Approach 2:
The patent intentionally introduces asymmetric optical path lengths for the first and second beams. The first beam travels through a first optical path with specific length, while the second beam travels through a second optical path with different length. This controlled asymmetry in path lengths, combined with the beam splitting and recombination, creates symmetric energy distribution in the final superimposed beam, resolving the crystallization quality issue.
2Manufacturing precision
If the optical system is expanded to include more mirrors for correcting energy distribution, then the manufacturing precision improves, but the device complexity and size increase
Solution Approach 1:
The beam splitter serves multiple functions: it divides the incident laser beam into separate first and second beams, and later recombines them after they have been manipulated by different mirrors. This multi-functionality reduces the need for additional dedicated components, maintaining energy distribution symmetry without excessive system complexity.
Solution Approach 2:
The patent manipulates the laser beam in multiple spatial dimensions by introducing different optical path lengths for the first and second beams. The first beam travels through a first optical path while the second beam travels through a second optical path with different length, creating temporal and spatial separation that enables precise energy distribution control when the beams are recombined.
3Reliability
If shaking occurs between laser shots, then the energy distribution becomes asymmetric, but adding correction modules increases manufacturing cost
Solution Approach 1:
The optical system provides inherent feedback stability through its symmetric design. The beam splitter and mirror arrangement ensures that fluctuations or shaking between laser shots affect both the first and second beams in a balanced manner, allowing the system to self-correct energy distribution asymmetry without requiring active feedback control mechanisms, thereby reducing manufacturing cost.
Solution Approach 2:
The patent designs the optical system with pre-established symmetry compensation capabilities. By configuring the first and second optical paths with controlled asymmetry in lengths and using a beam splitter to create balanced beam paths, the system proactively compensates for potential shaking effects before they cause crystallization defects, reducing the need for expensive active stabilization systems.
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 minimizes crystallization defects and extends the maintenance cycle of the laser apparatus, reducing operating costs while maintaining a compact optical system design.
Implementation Method 1
a splitter, a first mirror, and a second mirror positioned in a propagation path of an incident laser beam
Implementation Method 2
The first mirror may reflect a transmitted beam received from the splitter into a first reflected beam that is inverted in the long axis direction with respect to the first emitted beam
Implementation Method 3
the second mirror may reflect the first reflected beam into a second reflected beam that is inverted in the short axis direction with respect to the first reflected beam
Implementation Method 4
The long-short axis reversing module mixes a first emitted beam reflected from the splitter and a second emitted beam that passes through the splitter and is reflected from the first mirror and the second mirror to again pass through the splitter into the emitted laser beam
Data Source
AI summary
An optical system for a laser apparatus includes: a long-short axis reversing module that includes a splitter, a first mirror, and a second mirror positioned in a propagation path of an incident laser beam, where the first mirror includes a first submirror and a second submirror connected to each other at a predetermined angle therebetween. The optical system converts an incident laser beam having an asymmetric energy distribution into an emitted laser beam with a symmetric energy distribution.