SiC Single Crystal Growth with Stepped Sub-Growth Surfaces
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Solution Overview
Problem
The existing methods for manufacturing silicon carbide (SiC) single crystals suffer from high defect densities, including micropipe defects and threading screw dislocations, which increase leakage current and hinder the production of high-performance SiC power devices.
Innovation Solution
A manufacturing method involving a SiC seed crystal with a main growth surface composed of sub-growth surfaces, where the offset angles between successive sub-growth surfaces increase stepwise or continuously, ensuring that the threading screw dislocations are introduced with certainty in the c-plane facet during growth, thereby reducing defect generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a c-plane growth method is used to manufacture SiC single crystal, then the crystal can be grown with the c-plane exposed as growth surface, but the manufactured single crystal has great amount of defects including micropipe defects and c-axis threading screw dislocations
Solution Approach 1:
The growth surface is segmented into multiple sub-growth surfaces with different orientations. Instead of using a single c-plane growth surface, the invention divides the growth surface into first, second, and third sub-growth surfaces with progressively changing orientations, allowing controlled introduction of threading screw dislocations while maintaining manufacturing feasibility
Solution Approach 2:
The invention changes the orientation parameter of the growth surface by defining multiple sub-growth surfaces with different offset angles relative to the c-plane. The offset angle progressively increases from the first to the third sub-growth surface, transforming the crystal growth parameters to control dislocation formation and reduce defects
2Manufacturing precision
If threading screw dislocations are not introduced during growth, then defect-free crystals might be obtained, but heterogeneous polymorphous crystals and different surface orientation crystals may be generated
Solution Approach 1:
The invention performs preliminary action by intentionally introducing threading screw dislocations through the specifically designed sub-growth surfaces before the main crystal growth occurs. This preliminary introduction of dislocations prevents the subsequent formation of heterogeneous polymorphous crystals and different surface orientation crystals, ensuring compositional homogeneity
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 method results in SiC single crystals with a low potential for defect formation, reducing leakage current and enhancing the quality of SiC power devices by inhibiting the generation of heterogeneous polymorphous crystals and different surface orientation crystals.
Implementation Method 1
a SiC single crystal is grown on the growth surface by a method such as a sublimation recrystallization method
Implementation Method 2
a SiC single crystal is grown on the growth surface by a method such as a sublimation recrystallization method
Data Source
AI summary
A manufacturing method of a SiC single crystal includes growing a SiC single crystal on a surface of a SiC seed crystal, which satisfies following conditions: (i) the SiC seed crystal includes a main growth surface composed of a plurality of sub-growth surfaces; (ii) among directions from an uppermost portion of a {0001} plane on the main growth surface to portions on a periphery of the main growth surface, the SiC seed crystal has a main direction in which a plurality of sub-growth surfaces is arranged; and (iii) an offset angle θk of a k-th sub-growth surface and an offset angle θk+1 of a (k+1)-th sub-growth surface satisfy a relationship of θk<θk+1.