SiC Crucible for Stable Silicon Carbide Crystal Growth
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Solution Overview
Problem
Conventional methods for growing silicon carbide crystals using graphite crucibles face challenges such as compositional changes in the Si-C solution, precipitation of polycrystals on the crucible walls, and excessive carbon dissolution, leading to difficulties in maintaining stable and high-quality crystal growth.
Innovation Solution
A method utilizing a crucible with SiC as the main component, where Si and C are eluted from the crucible's high-temperature surface into the Si-C solution, and a temperature distribution is controlled to suppress polycrystal precipitation and compositional changes, with specific metal elements added to enhance carbon solubility, allowing for stable growth of high-quality SiC single crystals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a graphite crucible is used for SiC crystal growth, then carbon dissolution is enhanced, but compositional stability deteriorates and metal carbide formation occurs
Solution Approach 1:
The patent changes the crucible material parameter from graphite to SiC-containing material, which fundamentally alters the chemical interaction between the crucible and the Si-C solution. This parameter change prevents excessive carbon dissolution while maintaining adequate carbon supply for crystal growth, thereby stabilizing the Si/C ratio in the solution.
Solution Approach 2:
The patent uses a composite crucible material containing SiC as a main component combined with other materials. This composite structure provides both the chemical stability of SiC (preventing unwanted carbon dissolution and metal carbide formation) and the necessary carbon supply for crystal growth, resolving the contradiction between carbon dissolution and compositional stability.
2Productivity
If high temperature heating is applied to grow SiC crystal, then crystal growth rate is improved, but polycrystal precipitation on crucible wall increases
Solution Approach 1:
The patent changes the crucible material parameter to SiC-containing material, which has different thermal and chemical properties compared to graphite. This change allows high-temperature heating to proceed without causing excessive carbon dissolution and subsequent polycrystal precipitation on the crucible wall, enabling fast crystal growth while maintaining solution compositional stability.
3Quantity of substance
If metal element is added to enhance carbon solubility, then carbon dissolution is improved, but metal carbide generation occurs
Solution Approach 1:
The patent changes the crucible material from graphite to SiC-containing material, which prevents excessive carbon dissolution. This parameter change allows metal elements to be added in controlled amounts to enhance carbon solubility without causing harmful metal carbide generation, as the SiC crucible maintains the Si/C ratio stability in the solution.
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 effectively suppresses polycrystal precipitation and compositional changes, enabling the growth of high-quality silicon carbide crystals with few defects, similar to the Float Zone method, by maintaining a stable Si/C ratio and preventing metal carbide formation, thus improving crystal quality and growth stability.
Implementation Method 1
heating the crucible so as to reach a temperature of the surface of the crucible in contact with the Si-C solution to be sufficiently high to elute Si and C, which are derived from a main component SiC of the crucible, from a high-temperature surface region of the crucible in contact with the Si-C solution, into the Si-C solution
Implementation Method 2
the heating is carried out so as to form a temperature distribution where the temperature of the Si-C solution in the crucible formed of SiC as a main component increases from the top to the bottom
Implementation Method 3
at the bottom portion of the crucible have the highest temperature by control of induction heating from the high-frequency coil during a process for growing a SiC single crystal
Implementation Method 4
A SiC seed crystal is brought into contact with the Si-C melt and SiC is epitaxially grown on the SiC seed crystal to obtain a SiC single crystal
Implementation Method 5
The temperature distribution of the Si-C solution as mentioned above is formed by induction heating of the SiC crucible (1) by the high-frequency coil (10)
Data Source
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AI summary
In the present invention, a crucible formed of SiC as a main component is used as a container for a Si-C solution. The SiC crucible is heated such that, for example, an isothermal line representing a temperature distribution within the crucible draws an inverted convex shape; and Si and C, which are derived from a main component SiC of the crucible, are eluted from a high-temperature surface region of the crucible in contact with the SiC solution, into the Si-C solution, thereby suppressing precipitation of a SiC polycrystal on a surface of the crucible in contact with the Si-C solution. To the Si-C solution of this state, a SiC seed crystal is moved down from the upper portion of the crucible closer to the Si-C solution and brought into contact with the Si-C solution to grow a SiC single crystal on the SiC seed crystal.