SiC Single Crystal Curvature Control for Basal Plane Dislocation Suppression
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Solution Overview
Problem
The occurrence of basal plane dislocations (BPD) in SiC wafers is not sufficiently suppressed by controlling only the lattice deviation, which is a major defect in SiC semiconductor devices.
Innovation Solution
The use of SiC single crystals with a small relative difference in the curving amount of the atomic arrangement surface on multiple cut surfaces, where the difference between the curving amounts on perpendicular cut surfaces is 60 μm or less, and the curving amounts on cut surfaces rotated by 30° are similarly controlled, to suppress BPD during crystal growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If only the lattice deviation is controlled within a predetermined range, then the warpage amount and crystal orientation deviation are improved, but the basal plane dislocation (BPD) occurrence is not sufficiently suppressed
Solution Approach 1:
The invention changes the control parameter from absolute curving amount to relative curving amount ratio between different cut surfaces. By controlling the ratio of curving amounts on <11-20> and <1-100> cut surfaces to be within a specific range (0.5 to 2.0), the patent achieves better BPD suppression while maintaining manufacturing feasibility.
Solution Approach 2:
The invention extends the control from single-direction lattice deviation to multi-directional curving amount comparison. By evaluating curving amounts on multiple cut surfaces (<11-20> and <1-100> directions) and establishing a ratio relationship, the patent adds dimensional control to suppress BPD effectively.
2Reliability
If the curving amount of atomic arrangement surface is reduced, then the BPD occurrence is suppressed, but the manufacturing complexity increases due to multiple measurement directions
Solution Approach 1:
The invention measures curving amounts on specific high-impact cut surfaces (<11-20> and <1-100> directions) rather than all possible directions. By focusing on these critical surfaces and establishing a ratio relationship, the patent achieves effective BPD suppression with reduced measurement complexity compared to comprehensive multi-directional analysis.
Data Source
AI summary
A SiC single crystal, wherein difference between the curving amount of the atomic arrangement surface on the cut surface cut along the <1-100> direction through the center in plan view and the curving amount of the atomic arrangement surface on the cut surface cut along the <11-20> direction that passes through the center of view and is perpendicular to the <1-100> direction is 60 μm or less.