SiC Ingot Laser Slicing With Angled Scanning for Fewer Wafer Defects
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Solution Overview
Problem
Conventional SiC wafer slicing methods, such as wire sawing, are inefficient and result in significant material waste, particularly for high-hardness SiC ingots, limiting large-scale production and application, while existing laser slicing methods face challenges in controlling modified layer formation and crack propagation, leading to residual defects and low production yield.
Innovation Solution
A method involving laser slicing of SiC ingots by adjusting the rotation angle of the ingot and the incident angle of the laser beam to deviate the scanning direction of the laser beam relative to the primary flat within a specific angular range, using low-energy and high-energy laser beams to form controlled modified layers and cracks, optimizing parameters like wavelength, pulse width, and focal spot diameter to enhance precision and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wire sawing technology is used to slice SiC ingots, then the slicing process can be performed with conventional equipment, but the processing time becomes excessively long and material waste reaches 70% to 80%
Solution Approach 1:
The patent replaces the mechanical wire sawing system with a laser-based system. The laser beam modifies the SiC ingot material through optical energy, creating a modified layer that enables subsequent mechanical separation. This substitution eliminates the need for mechanical contact during the critical modification phase, dramatically reducing processing time and material waste while achieving complete slicing capability.
Solution Approach 2:
The patent changes the fundamental parameter of the slicing process from mechanical force to optical energy. By using laser radiation with specific wavelengths and intensities, the material properties of SiC are modified locally, creating a zone of altered physical properties that facilitates separation. This parameter change enables high-precision slicing with minimal material removal and no mechanical contact during modification.
2Ease of manufacture
If wire sawing technology is used to slice SiC ingots, then the slicing process can be performed with conventional equipment, but material waste reaches 70% to 80%
Solution Approach 1:
The patent replaces the mechanical wire sawing system with a laser-based system. The laser beam modifies the SiC ingot material through optical energy, creating a modified layer that enables subsequent mechanical separation. This substitution eliminates the need for mechanical contact during the critical modification phase, dramatically reducing processing time and material waste while achieving complete slicing capability.
Solution Approach 2:
The patent changes the fundamental parameter of the slicing process from mechanical force to optical energy. By using laser radiation with specific wavelengths and intensities, the material properties of SiC are modified locally, creating a zone of altered physical properties that facilitates separation. This parameter change enables high-precision slicing with minimal material removal and no mechanical contact during modification.
3Ease of operation
If laser scanning follows path (1) or path (2) to process SiC ingots, then the processing can be performed with standard laser parameters, but residual defects form on the wafer surface reducing production yield
Solution Approach 1:
The patent introduces asymmetric processing by deviating the laser scanning direction from the standard crystal orientation paths. Instead of following the symmetric path (1) or (2) that aligns with crystal axes, the laser scans at a specific deviation angle (5°-15°) from the primary flat. This asymmetric scanning pattern prevents the formation of symmetric defect patterns and eliminates residual defects on the wafer surface that would otherwise compromise quality.
Solution Approach 2:
The patent changes the scanning parameter from standard crystal orientation alignment to a specific deviation angle (5°-15°) from the primary flat. This parameter modification alters the interaction between laser energy and crystal structure, preventing the formation of defect-prone patterns while maintaining effective modified layer creation. The changed scanning parameter eliminates the harmful symmetry that leads to residual defects.
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 method improves the formation and propagation of modified layers and cracks, reducing residual defects, increasing production yield, and minimizing material waste, thereby enhancing processing efficiency and reducing costs for large-scale industrial applications.
Implementation Method 1
forming a modified layer parallel to a first surface of a SiC ingot from the first surface, where the modified layer is formed by irradiating the ingot with a laser beam for modification and positioning a focal point of the laser beam for modification at a depth from the first surface corresponding to a thickness of a wafer to be produced
Implementation Method 2
extending cracks from the modified layer to a cleavage plane of the SiC ingot so as to slice the SiC wafer from the ingot along the cracks
Data Source
AI summary
The present disclosure relates to a wafer generation method, in particular to a method and equipment for generating wafers by laser slicing of SiC ingots. This method improves formation of modified layers and propagation paths of cracks, reduces residual wafer defects, and enhances production yield by adjusting a rotation angle of a SiC ingot and a scanning direction of a laser beam so that the scanning direction of the laser beam deviates from a primary flat within a specific angular range.