SiC Crucible Oxygen Control for Stable Single Crystal Growth
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Solution Overview
Problem
Conventional methods for growing silicon carbide (SiC) single crystals face challenges such as composition variation of the Si-C solution, excessive carbon melting, and precipitation of polycrystals on the crucible surface, leading to instability and defects in the crystal growth process.
Innovation Solution
A SiC crucible or sintered body with an oxygen content of 100 ppm or less is used, allowing Si and C to elute into the Si-C solution, and a SiC seed crystal is brought into contact with the solution to grow a high-quality SiC single crystal, with optional addition of metal elements to enhance solubility and control temperature within the range of 1300°C to 2300°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a graphite crucible is used in the solution method, then carbon can be supplied to the Si-C solution, but composition variation occurs and polycrystals precipitate on the crucible surface
Solution Approach 1:
The invention changes the material parameter of the crucible from graphite to SiC with specific oxygen content (100-1000 ppm). This parameter change transforms the crucible's interaction with the Si-C solution, enabling controlled carbon supply through carbon monoxide generation while maintaining solution composition stability and preventing polycrystal precipitation.
Solution Approach 2:
The SiC crucible creates a chemically inert environment that prevents unwanted reactions. The controlled oxygen content in the SiC crucible generates carbon monoxide that supplies carbon to the solution without causing excessive carbon dissolution or polycrystal formation, maintaining a stable growth environment.
2Quantity of substance
If carbon is excessively melted into the Si-C solution, then the solution becomes carbon-rich, but this causes composition variation and defects in crystal growth
Solution Approach 1:
The SiC crucible acts as a feedback-controlled carbon source. The controlled oxygen content (100-1000 ppm) in the crucible generates carbon monoxide at a regulated rate, providing continuous but controlled carbon supply to the Si-C solution. This feedback mechanism prevents carbon overload while maintaining adequate carbon levels for high-quality crystal growth.
Solution Approach 2:
By precisely controlling the oxygen content parameter in the SiC crucible (100-1000 ppm), the invention regulates the carbon supply rate through carbon monoxide generation. This parameter control prevents excessive carbon dissolution into the solution, maintaining optimal carbon levels for defect-free crystal growth.
3Productivity
If polycrystals precipitate on the crucible surface, then carbon supply is disrupted, but this leads to instability in crystal growth and increased defects
Solution Approach 1:
The SiC crucible with controlled oxygen content creates a chemically stable environment that prevents polycrystal precipitation on the crucible surface. This inert environment maintains consistent carbon supply through controlled carbon monoxide generation, ensuring reliable and stable crystal growth without interruptions from polycrystal formation.
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 stabilizes the growth of high-quality SiC single crystals with few defects, suitable for use in SiC semiconductor devices, by suppressing composition variation and polycrystal precipitation, and reducing void formation.
Implementation Method 1
allowing Si and C to elute into the Si-C solution
Implementation Method 2
a SiC single crystal is allowed to epitaxially grow on the SiC seed crystal
Implementation Method 3
C is allowed to dissolve in the Si melt contained in a graphite crucible, from the high temperature part of the lower portion of the crucible
Data Source
AI summary
In the present invention, in producing a SiC single crystal in accordance with a solution method, a crucible containing SiC as a main component and having an oxygen content of 100 ppm or less is used as the crucible to be used as a container for a Si—C solution. In another embodiment, a sintered body containing SiC as a main component and having an oxygen content of 100 ppm or less is placed in the crucible to be used as a container for a Si—C solution. The SiC crucible and SiC sintered body are obtained by molding and baking a SiC raw-material powder having an oxygen content of 2000 ppm or less. SiC, which is the main component of these, serves as a source for Si and C and allows Si and C to elute into the Si—C solution by heating.