SiC Substrate Peripheral Edge Defect Control for Epitaxial Growth
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Solution Overview
Problem
SiC substrates often crack during epitaxial growth due to micropipe-like defects at the peripheral edge, leading to unusable substrates and operational issues in growth furnaces, with existing techniques failing to effectively reduce defect density and prevent cracking.
Innovation Solution
A SiC substrate with a controlled density of composite defects at the peripheral edge, where hollow portions and dislocation lines are connected, ranging from 0.01 to 10 pieces/cm², is used to minimize cracking during epitaxial growth, and a method involving substrate selection and preparation to ensure this defect density is maintained.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional SiC substrates are used for epitaxial growth, then manufacturing process can proceed, but substrate cracking occurs due to micropipe-like defects at peripheral edge
Solution Approach 1:
The invention applies local quality by establishing different defect density requirements for different regions of the substrate. Specifically, the peripheral edge portion (within 5mm from outer periphery) is controlled to have a specific defect density range (0.01-10 pieces/cm²), while the central portion can tolerate higher defect densities. This regional differentiation allows the substrate to maintain reliability where it matters most (periphery) while maximizing usable substrate area.
Solution Approach 2:
The invention changes the parameter of defect density from being uniformly minimized across the entire substrate to being selectively controlled in the peripheral region. By setting a specific numerical range for defect density (0.01-10 pieces/cm²) in the peripheral edge portion, the invention transforms the quality criterion from absolute (zero defects) to relative and regional (controlled density in critical areas), thereby preventing cracking while maintaining substrate utilization.
2Reliability
If substrates with low defect density are selected, then cracking is reduced, but substrate selection becomes more complex and time-consuming
Solution Approach 1:
The invention simplifies detection by focusing inspection resources only on the peripheral edge portion (within 5mm from outer periphery) rather than requiring comprehensive inspection of the entire substrate. This local quality approach reduces measurement complexity while maintaining crack resistance, as the peripheral region is the critical area for crack initiation.
Solution Approach 2:
The invention applies partial action by inspecting only the critical peripheral region rather than the entire substrate. This selective inspection approach (checking only the outer 5mm band) is sufficient to predict crack resistance without requiring exhaustive examination of the whole substrate, thereby reducing detection difficulty and time.
3Reliability
If peripheral defects are removed to prevent cracking, then substrate reliability improves, but manufacturing cost increases due to reduced usable substrate area
Solution Approach 1:
The invention optimizes substrate utilization by applying quality control only where necessary (peripheral 5mm region) and accepting higher defect densities in the central usable area. This allows maximum substrate area to be utilized for device fabrication while maintaining epitaxial growth stability through controlled peripheral defect density.
Solution Approach 2:
The invention changes the defect density parameter from a uniform strict limit across the entire substrate to a differentiated approach: maintaining defect density within 0.01-10 pieces/cm² in the peripheral region (critical for growth stability) while allowing higher densities in the central region (usable for devices). This parameter differentiation maximizes substrate utilization while ensuring growth stability.
Data Source
AI summary
A SiC substrate includes a first principal surface, a second principal surface disposed on a side opposite to the first principal surface, and an outer periphery connected to the first principal surface and the second principal surface, wherein a density of composite defects present at a peripheral edge portion of the SiC substrate, in which a hollow portion and a dislocation line extending from the hollow portion are connected to each other is equal to or greater than 0.01 pieces/cm2 and equal to or less than 10 pieces/cm2.