Monocrystalline Silicon Peel-Off Layers for Faster Substrate Slicing
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Solution Overview
Problem
The existing methods for manufacturing monocrystalline silicon substrates from ingots using wire saws result in low productivity due to significant material wastage and surface irregularities, while laser-based methods increase processing time, reducing throughput.
Innovation Solution
A method involving the formation of peel-off layers with modified portions and cracks in monocrystalline silicon ingots using a laser beam, where the laser is applied alternately to regions spaced at specific angles and distances, allowing simultaneous application to multiple regions to increase throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a wire saw is used to slice substrates from monocrystalline silicon ingots, then substrates can be manufactured, but material wastage increases and productivity decreases
Solution Approach 1:
The patent replaces the mechanical wire saw slicing process with a laser-based peeling process. The laser beam creates modified portions and cracks in the ingot, allowing substrates to be separated through peeling rather than mechanical cutting. This substitution eliminates the need for wide saw kerfs (approximately 300 μm) and reduces material wastage while improving productivity.
Solution Approach 2:
The laser processing induces phase transitions in the monocrystalline silicon, creating modified portions with altered crystal structures. These modified portions serve as initiation points for crack development, enabling controlled separation of substrates from the ingot without mechanical contact.
2Loss of substance
If laser beam is applied to form peel-off layers in monocrystalline silicon ingots, then material wastage is reduced, but processing time increases and throughput decreases
Solution Approach 1:
The patent divides the ingot into multiple regions and applies the laser beam to multiple regions simultaneously or in parallel. By processing multiple regions concurrently rather than sequentially, the overall processing time is reduced while maintaining the low material wastage advantage of the laser peeling method.
Solution Approach 2:
The patent transitions from one-dimensional sequential laser processing to multi-dimensional parallel processing by applying laser beams to multiple regions across the ingot simultaneously. This spatial distribution of processing operations reduces total processing time while maintaining precision.
3Ease of manufacture
If wire saw slicing is used, then substrates can be obtained, but surface irregularities and curvature occur requiring additional finishing steps
Solution Approach 1:
The patent replaces mechanical wire saw cutting with laser-induced peeling. The laser creates controlled modified portions and cracks that allow substrates to separate cleanly from the ingot, eliminating the surface irregularities and curvature caused by mechanical slicing. This results in substrates with superior surface flatness that require minimal or no additional finishing steps.
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 enhances the productivity of substrate manufacturing by reducing material wastage and processing time, improving the efficiency of the laser-based method compared to successive laser application techniques.
Implementation Method 1
forming peel-off layers including a plurality of modified portions and cracks developed respectively from the modified portions, respectively in a plurality of regions included in the workpiece by alternately repeating a laser beam applying step of relatively moving, along the first direction, the workpiece and a plurality of focused spots formed from respective laser beams having a wavelength transmittable through monocrystalline silicon
Data Source
AI summary
The application of laser beams to at least two of a plurality of regions extending along a predetermined direction and the changing of at least two regions to which the laser beams are to be applied are alternately repeated to form peel-off layers in the ingot that include a plurality of modified portions positioned at a predetermined depth from the surface of the workpiece and cracks developed from the respective modified portions. The laser beams for forming the peel-off layers in the workpiece are thus simultaneously applied to the at least two of the regions. Therefore, it is possible to increase the throughput compared with a process in which the laser beams are applied successively to the regions.