Chamfered Silicon Carbide Substrate Edge Geometry
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Solution Overview
Problem
The mechanical brittleness of silicon carbide substrates leads to chipping and breakouts during processing, affecting the quality of epitaxial layers and reducing the yield of epitaxial deposition, as conventional chamfering methods do not adequately address the anisotropic mechanical stability of the substrate edges.
Innovation Solution
A silicon carbide substrate with a double bevel geometry, featuring a first bevel angle between 20° and 50° and a second bevel angle between 45° and 75°, enhancing mechanical stability and preventing fractures and chipping, while ensuring a smooth transition for polishing and double-sided polishing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional chamfering methods are used on silicon carbide substrates, then the substrate edges are mechanically treated for stability, but the anisotropic mechanical brittleness causes chipping and breakouts during processing
Solution Approach 1:
The invention changes the geometric parameters of the chamfer by specifying precise angle ranges (first bevel angle 20°-50°, second bevel angle 45°-75%) to optimize the balance between mechanical stability and prevention of chipping. This parameter optimization resolves the contradiction by finding the optimal chamfer geometry that provides edge stability without causing mechanical failures during processing
Solution Approach 2:
The chamfer is divided into two distinct bevel surfaces with different angles rather than a single chamfer. The first bevel surface (20°-50°) provides one function while the second bevel surface (45°-75°) provides another, allowing each segment to address specific mechanical requirements and prevent different types of failures
2Stability of the object's composition
If the substrate edge is mechanically treated for stability, then mechanical stability is improved, but breakouts and chipping occur during processing
Solution Approach 1:
By optimizing the chamfer angle parameters within specific ranges, the invention changes the stress distribution parameters at the substrate edge, preventing stress concentration that leads to chipping while maintaining mechanical stability
Solution Approach 2:
The double bevel chamfer is applied in advance during substrate fabrication to preemptively prevent chipping and breakouts that would occur during subsequent processing steps, addressing the mechanical brittleness issue before it manifests as defects
3Ease of manufacture
If conventional single bevel chamfering is applied, then the processing is simpler, but the yield of epitaxial deposition is reduced due to fractures
Solution Approach 1:
The chamfering process is segmented into two bevel operations with specific angle ranges, which increases process complexity slightly but dramatically improves substrate integrity and epitaxial deposition yield by preventing fractures during handling and processing
Solution Approach 2:
The invention specifies optimal parameter ranges for both bevel angles that balance manufacturing complexity with yield improvement, finding the sweet spot where the additional processing step justifies the significant increase in epitaxial deposition yield
Data Source
AI summary
The present invention relates to a chamfered silicon carbide substrate which is essentially monocrystalline, and to a corresponding method of chamfering a silicon carbide substrate. The silicon carbide substrate (100) comprises a main surface (102) and a circumferential end face surface (114) which is essentially perpendicular to the main surface (102), and a chamfered peripheral region (110), wherein a first bevel surface (106) of the chamfered peripheral region (110) includes a first bevel angle (a1) with said main surface (102), and wherein a second bevel surface (108) of the chamfered peripheral region (110) includes a second bevel angle (a2) with said end face surface (114), wherein, in more than 75% of the peripheral region, said first bevel angle (a1) has a value in a range between 20° and 50°, and said second bevel angle (a2) has a value in a range between 45° and 75°.