SiC Single Crystal Ingot Growth via Seed Rotation
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Solution Overview
Problem
Existing methods for producing SiC single crystals by solution processes face challenges in achieving high-quality crystals with minimal inclusions, as inclusions act as macrodefects and are unacceptable for device materials, and previous methods like JP 2006-117441 A require complex synchronization of crucible and seed shaft rotation, which is insufficient for stable inclusion-free growth.
Innovation Solution
A method involving a seed crystal substrate contacted with a Si-C solution having a temperature gradient that decreases from the interior to the surface, with the temperature at the outer peripheral section below the crystal growth plane being lower than at the center section, causing the Si-C solution to flow from the center to the outer peripheral section, promoting a concave crystal growth plane and minimizing inclusions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If both the crucible and the seed shaft are rotated to stir the molten liquid, then the crystal growth is promoted, but the procedure becomes complex due to synchronization requirements and inclusions are still generated
Solution Approach 1:
The patent extracts the stirring function from the crucible rotation and transfers it to the seed crystal rotation alone. By rotating only the seed crystal holding shaft at a higher speed than the crucible, the molten liquid is stirred effectively without requiring complex synchronization between two rotating components, thus simplifying the system while maintaining productivity
Solution Approach 2:
Instead of rotating the crucible to stir the molten liquid as in conventional methods, the patent inverts the approach by rotating the seed crystal holding shaft. This reversal of the stirring mechanism achieves better mixing and prevents inclusion generation without the complexity of synchronized dual rotation
2Productivity
If the crucible is rotated at high speed to stir the molten liquid, then crystal growth is promoted, but inclusions are generated and incorporated into the grown crystal
Solution Approach 1:
The patent employs dynamic rotation speed control where the seed crystal holding shaft rotates at a higher speed than the crucible during crystal growth. This dynamic speed differential creates effective stirring that promotes crystal growth while preventing inclusion incorporation, achieving both high productivity and manufacturing precision
Solution Approach 2:
The patent changes the rotational speed parameter relationship between the crucible and seed crystal holding shaft. By setting the seed crystal shaft rotation speed higher than the crucible rotation speed, the system achieves optimal stirring intensity that promotes growth without generating inclusions, thus resolving the contradiction between productivity and crystal quality
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 approach enables the production of high-quality SiC single crystals with minimal inclusions across the desired thickness and diameter ranges, ensuring a concave crystal growth plane and stable crystal growth without inclusions.
Implementation Method 1
contacted with a Si-C solution having a temperature gradient such that the temperature decreases from the interior toward the surface
Implementation Method 2
causing the Si-C solution to flow from the center section directly below the interface with the crystal growth plane to the outer peripheral section
Implementation Method 3
a SiC crystal layer is deposited and grown on a seed crystal substrate set in the low temperature section
Implementation Method 4
a SiC crystal layer is deposited and grown on a seed crystal substrate
Data Source
Figure 1~2(b)
Figure 3~4
Figure 5~6
AI summary
Provided are: a high-quality SiC single crystal ingot that suppresses the generation of inclusions; and a production method for said SiC single crystal ingot. The present invention pertains to a SiC single crystal ingot including a seed crystal substrate and a SiC growth crystal grown using the solution method and using the seed crystal substrate as the origin thereof, said growth crystal having a recessed crystal growth surface and not including inclusions.