SiC Substrate Groove Design for Crystal Defect Reduction
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Solution Overview
Problem
Existing methods for producing silicon carbide substrates face challenges in forming large-diameter single crystal ingots with few crystal defects, as the high crystallization temperature of silicon carbide makes it difficult to achieve using the pulling-up method, and epitaxial growth techniques on offset substrates or substrates with grooves do not sufficiently reduce crystal defects.
Innovation Solution
A single crystal substrate with a foundation substrate featuring grooves oriented in the [110] direction and an angle between the first and second crystal faces greater than 70.6°, along with a Si{100} plane between grooves, is used for epitaxial growth of silicon carbide, which reduces crystal defects by allowing the growth layer to be efficiently and stably formed with fewer defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sublimation method is used to form a single crystal ingot of SiC, then a single crystal ingot can be formed, but it is very difficult to form a substrate having a large diameter and few crystal defects
Solution Approach 1:
The substrate surface is divided into multiple regions by forming grooves that extend in the <110> direction. These grooves segment the growth surface into distinct areas with different crystal orientations, allowing defects to be confined and eliminated locally while maintaining overall substrate quality and production efficiency.
Solution Approach 2:
Different regions of the substrate are given different local qualities through the groove structure. The grooves create areas with specific crystal face orientations (first crystal face and second crystal face at angles greater than 70.6°) that are optimized for defect reduction, while other regions maintain the original substrate characteristics for efficient growth.
2Reliability
If an offset substrate is used for epitaxial growth, then some crystal defects can be reduced, but reduction in crystal defects cannot be sufficiently achieved
Solution Approach 1:
The groove structure introduces asymmetry into the substrate surface, creating non-uniform crystal orientations with specific angle relationships (greater than 70.6° between first and second crystal faces). This asymmetric structure is more effective at reducing crystal defects compared to the symmetric offset substrate approach, while maintaining reasonable structural complexity.
3Temperature
If cubic SiC is epitaxially grown on a substrate, then growth can occur at a relatively low temperature, but reduction in crystal defects cannot be sufficiently achieved
Solution Approach 1:
The groove structure is prepared in advance on the substrate before epitaxial growth begins. This preliminary structuring creates predetermined crystal orientation relationships that will guide defect reduction during the low-temperature cubic SiC growth process, ensuring defect reduction capability is built into the substrate architecture before growth occurs.
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 effectively reduces crystal defects in the silicon carbide growth layer, enabling the production of high-quality silicon carbide substrates suitable for power devices by associating and vanishing defects within the grooves and planar faces, resulting in a substrate with improved mechanical strength and reduced defect density.
Implementation Method 1
when silicon carbide is epitaxially grown by using the single crystal substrate including the grooves as a foundation, crystal defects in a silicon carbide crystal can be efficiently vanished or reduced
Data Source
AI summary
A single crystal substrate is provided and is characterized in that the single crystal substrate has a foundation substrate provided with a plurality of grooves, which include a first crystal face and a second crystal face opposed to the first crystal face in an inner face thereof, and the extending direction of which is a <110> direction, and an angle formed by the first crystal face and the second crystal face is more than 70.6°. Further, it is preferred that the angle formed by the first crystal face and the second crystal face is 100° or more and 176° or less.