SiC Ingot Facet Geometry to Reduce Laser Output Changes
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Solution Overview
Problem
The challenge in laser processing of SiC ingots arises from the presence of facets, which require frequent adjustments in laser output, leading to reduced throughput due to the varying resistance values of different crystal growth patterns.
Innovation Solution
The shape of the facet in the SiC ingot is controlled by ensuring that the length of the first side of a virtual rectangle surrounding the facet, parallel to a specific crystal direction, is less than 0.3 times the ingot diameter, thereby minimizing the need for laser output adjustments during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the laser output is increased to process facets with lower resistance values, then sufficient cracks can be generated, but the processed surface becomes rough
Solution Approach 1:
The patent applies parameter changes by controlling the facet shape parameters (Lx/D and Ly/D ratios) to specific ranges. This geometric parameter control modifies the electrical resistance distribution, allowing consistent laser processing at a fixed output level, thereby resolving the contradiction between sufficient crack generation and surface quality
2Reliability
If the laser output is frequently adjusted to accommodate different resistance values in different regions, then processing can be optimized for each region, but the throughput of the processing decreases
Solution Approach 1:
The patent applies homogeneity by designing the facet shape parameters (Lx/D < 0.3 and Ly/D < 0.5) to create a more uniform electrical resistance distribution across the ingot cross-section. This homogenization allows the entire ingot to be processed with a single laser output setting, eliminating frequent adjustments and improving throughput while maintaining processing quality
3Ease of manufacture
If the facet shape is not controlled, then the crystal growth pattern is naturally formed, but the number of laser output changes increases reducing efficiency
Solution Approach 1:
The patent applies parameter changes by imposing specific geometric constraints on the facet shape (Lx/D < 0.3 and Ly/D < 0.5) during crystal growth. These parameter controls modify the resistance distribution to enable efficient laser processing with minimal output changes, resolving the contradiction between natural crystal formation and processing efficiency
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 efficiency of laser processing by reducing the number of laser output changes, resulting in improved production efficiency and throughput for producing SiC substrates.
Implementation Method 1
cracks are created in a SiC ingot with a laser
Implementation Method 2
cracks are created in a SiC ingot with a laser
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
This SiC ingot includes a facet, wherein, when a diameter of the SiC ingot is represented as D and in a plan view in a crystal growth direction, a virtual rectangle that surrounds the facet with a minimum area and has a first side parallel to a <11-20> direction and a second side parallel to a <1-100> direction is drawn, and a length of the first side of the virtual rectangle is represented as Lx, Lx/D < 0.3 is satisfied at a first end which is a terminal of the crystal growth direction.