Laser Crystallizing Apparatus Polarization Control
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Solution Overview
Problem
Current laser crystallization methods for converting amorphous silicon to polycrystalline silicon suffer from high energy loss due to random polarization of laser beams and require multiple shots, leading to inefficient grain alignment and increased equipment wear.
Innovation Solution
A laser crystallizing apparatus that converts randomly polarized laser beams into linearly polarized beams using a combination of half wave plates and polarization beam splitters, allowing for optimal grain alignment and energy distribution, reducing the number of required shots and extending equipment lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a randomly polarized laser beam is used for laser crystallization, then the crystallization process can be performed, but grain alignment is poor and multiple shots (15 or more) are required
Solution Approach 1:
The invention changes the polarization state parameter of the laser beam from random to linear by introducing a polarization control module with half-wave plates. This parameter change enables effective grain alignment and reduces the number of shots required from 15 or more to just a few shots, simultaneously improving manufacturing precision and productivity.
2Manufacturing precision
If a polarization module with multiple lenses and mirrors is used to convert random polarization to linear polarization, then grain alignment is improved, but the device complexity increases
Solution Approach 1:
The polarization control module is segmented into independent functional components: half-wave plates for polarization rotation, mirrors for beam direction control, and polarization beam splitters for beam separation and recombination. This modular segmentation allows each component to perform a specific function, improving grain alignment while keeping the overall system manageable and maintainable.
3Reliability
If UV excimer laser is used for crystallization, then amorphous silicon can be converted to polycrystalline silicon, but energy loss is high due to 40% or more reflectance
Solution Approach 1:
The invention applies preliminary action by using the polarization control module to optimize the polarization state of the laser beam before it reaches the amorphous silicon target. By pre-adjusting the polarization to linear state with appropriate orientation, the system maximizes light absorption and minimizes reflectance loss, thereby improving energy utilization efficiency while maintaining reliable crystallization.
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
Enhances grain alignment and energy efficiency by converting random polarization to linear polarization, increasing the optimal energy density and reducing the number of shots needed for crystallization, thereby improving the manufacturing process and extending equipment lifespan.
Implementation Method 1
at least one half wave plate (HWP) that shifts a polarization axis direction of the incident laser beam received from the laser generator
Implementation Method 2
at least one polarization beam splitter (PBS) which partially reflects and partially transmits the laser beam
Implementation Method 3
at least one mirror that fully reflects the laser beam
Implementation Method 4
irradiating a laser beam to amorphous silicon to phase-change the amorphous silicon into polycrystalline silicon
Implementation Method 5
When using a 308 nm wavelength UV excimer laser, the UV light is fully absorbed in a wavelength range of about 300 nm to about 400 nm
Data Source
AI summary
A laser crystallizing apparatus includes a laser generator that generates an incident laser beam that includes a P polarization component and an S polarization component, an optical system that converts the incident laser beam to generate an emitted laser beam, and a stage on which is mounted a target substrate with a target thin film which is laser-crystallized by being irradiated by the emitted laser beam. The optical system includes at least one half wave plate (HWP) that shifts a polarization axis direction of the incident laser beam received from the laser generator, at least one mirror that fully reflects the laser beam, and at least one polarization beam splitter (PBS) which reflects a part of the laser beam and transmits the other part of the laser beam.