Laser Annealing Wavelength Switching With Single-Axis Beam Alignment
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Solution Overview
Problem
The quality of polysilicon films formed by laser annealing varies due to changes in irradiation position and range of the laser beam when the wavelength is adjusted according to crystal grain size, leading to inconsistent film quality.
Innovation Solution
A laser annealing device with multiple laser light sources emitting different wavelengths, a diffraction grating to combine these beams on a single optical axis, and a controller to select the appropriate sources based on crystal grain size, ensuring uniform irradiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the wavelength of the laser beam is changed according to crystal grain size to adjust absorption coefficient and penetration depth, then the quality control of polysilicon film is improved, but the irradiation position and range of the laser beam change due to spatial synthesis from multiple light sources
Solution Approach 1:
A diffraction grating is introduced as an intermediary optical element to combine multiple laser beams of different wavelengths onto a single optical axis. The diffraction grating disperses and redirects the laser beams from multiple light sources so that they converge at the same focal point and travel along the same optical path, eliminating the spatial displacement that would otherwise occur with direct spatial synthesis.
Solution Approach 2:
The system changes the wavelength parameter of the laser beam according to the crystal grain size of the amorphous silicon film to optimize absorption coefficient and penetration depth. By selecting different wavelengths (e.g., 405nm, 450nm, 532nm) based on the specific crystal grain size requirements, the system achieves precise control over the annealing process and polysilicon film quality without compromising irradiation consistency.
2Adaptability or versatility
If multiple laser light sources are used to emit different wavelengths for adjusting absorption characteristics, then the adaptability to different crystal grain sizes is improved, but the device complexity increases due to multiple light sources and optical paths
Solution Approach 1:
The diffraction grating serves as a universal optical component that can handle multiple laser wavelengths simultaneously, directing them all onto a single optical axis. This multi-functional element eliminates the need for separate optical paths for each wavelength, thereby reducing overall system complexity while maintaining the ability to adapt to different crystal grain sizes through wavelength selection.
Solution Approach 2:
Multiple laser beams of different wavelengths are merged onto a single optical axis using the diffraction grating. By combining the optical paths of multiple light sources into one unified path, the system achieves adaptability to various crystal grain sizes without proportionally increasing device complexity, as the beams share common optical components downstream of the grating.
3Manufacturing precision
If laser beams are condensed from multiple laser light sources disposed at different positions, then the spatial synthesis is achieved, but the irradiation position and range change due to beam deviation angle differences when light source wavelength is changed
Solution Approach 1:
The diffraction grating acts as an intermediary that corrects the beam deviation angles caused by different wavelengths. By dispersing and redirecting each wavelength-specific beam through controlled diffraction, the grating ensures that all beams converge at the same focal point and maintain consistent irradiation position and range, regardless of their original wavelength or source 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 approach allows for uniform control of polysilicon film quality while maintaining consistent irradiation position and range, improving the formation process by adjusting absorption coefficients and penetration depth.
Implementation Method 1
a diffraction grating that diffracts the laser beams emitted from the laser light sources
Implementation Method 2
the longer the wavelength of the laser beam is, the more difficult to absorb the beam is, and thus the penetration depth of the laser beam into the amorphous silicon film increases
Data Source
AI summary
Laser annealing device (1) irradiates amorphous silicon film (W1) with laser beam (Li) to perform an annealing process. The laser annealing device includes: a plurality of laser oscillators (2i) that emit laser beams having mutually different wavelengths (λi); diffraction grating (3) that diffracts the laser beams emitted from the laser oscillators; and controller (6) that switches on and off states of emission of the laser beams by the laser oscillators. The laser oscillators are disposed at mutually different positions, and the laser beams emitted from the laser oscillators are diffracted on identical optical axis (A) by the diffraction grating. The controller can select at least one or more of the laser oscillators for turning on emission of the laser beams from among the plurality of laser oscillators in accordance with any crystal grain size of the amorphous silicon film.