SiC Substrate Edge Geometry for Epitaxial Film Flatness
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Solution Overview
Problem
Silicon carbide epitaxial films often exhibit level differences (slip) due to damage at the contact points between the substrate's orientation flat and arc portions during epitaxial film formation.
Innovation Solution
A silicon carbide single crystal substrate with a circumferential edge featuring a linear orientation flat portion, a first arc portion, and a second arc portion with a smaller radius, which are ground to prevent damage and chipping at the contact points, thereby suppressing level differences in the epitaxial film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional circumferential edge portion with a simple arc shape is used, then the manufacturing process is simple, but damage and chipping occur at the contact points between the orientation flat and arc portions, causing level differences in the epitaxial film
Solution Approach 1:
The circumferential edge portion is segmented into multiple distinct portions: a first arc portion, a second arc portion with a different radius, and an intermediate portion connecting them. This segmentation allows each portion to have optimized geometry that prevents damage at contact points while maintaining manufacturing feasibility.
Solution Approach 2:
Different portions of the circumferential edge are given different local geometries. The first arc portion has one radius of curvature, the second arc portion has a different radius, and the intermediate portion provides a smooth transition. This local variation in geometry prevents stress concentration and chipping at specific contact points.
2Manufacturing precision
If the circumferential edge portion is ground to remove damage at contact points, then the level difference in the epitaxial film is suppressed, but the manufacturing process time increases
Solution Approach 1:
The circumferential edge portion is designed with pre-ground contact points that have appropriate radii of curvature before the epitaxial film formation process. This preliminary preparation prevents damage during film formation, eliminating the need for additional post-processing steps to remove chipping or level differences.
Solution Approach 2:
The radii of curvature of the circumferential edge portion are carefully controlled within specific ranges. By optimizing these geometric parameters, the design achieves both damage prevention and efficient manufacturing, balancing precision requirements with production time constraints.
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
The described substrate and manufacturing method effectively prevent level differences in silicon carbide epitaxial films by removing damage at the contact points, enhancing film quality and reducing chipping and misalignment.
Implementation Method 1
the first arc portion, the contact point, and the orientation flat portion are ground while rotating the silicon carbide single crystal substrate. A second arc portion connecting the orientation flat portion and the first arc portion and having a second radius smaller than the first radius is formed by grinding the first arc portion, the contact point, and the orientation flat portion.
Data Source
AI summary
A silicon carbide single crystal substrate includes a first main surface, a second main surface, and a circumferential edge portion. The second main surface is opposite to the first main surface. The circumferential edge portion connects the first main surface and the second main surface. The circumferential edge portion has a linear orientation flat portion, a first arc portion having a first radius, and a second arc portion connecting the orientation flat portion and the first arc portion and having a second radius smaller than the first radius, when viewed along a direction perpendicular to the first main surface.