Gas-Permeable Separator for Single Crystal Growth Crucible
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Solution Overview
Problem
Current methods for producing single crystals, such as silicon carbide, face challenges in accurately adjusting growth rate and kinetics, particularly for large crystals, leading to difficulties in quality control.
Innovation Solution
A method and growth crucible design that control temperature gradients within the crucible, using a gas-permeable separator to manage heat flows and material transport, allowing for precise adjustment of growth conditions to enhance crystal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the growth rate and growth kinetics are controlled with limited accuracy in state-of-the-art processes, then the production of large single crystals can be achieved, but the quality control becomes difficult
Solution Approach 1:
The patent applies local quality by creating different temperature zones within the growth crucible. A temperature gradient is established with a hotter source material region and a cooler crystal growth region, allowing different local conditions optimized for each process stage. This spatial differentiation of temperature conditions enables precise control of growth kinetics while maintaining overall process simplicity
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the temperature gradient between source material and crystal. By controlling the axial temperature gradient through the relationship between source material temperature and crystal growth zone temperature, the system achieves precise control over growth rate and kinetics without requiring complex external control mechanisms
2Manufacturing precision
If temperature gradients are not controlled in the radial direction, then the growth process is simpler, but the quality of large single crystals deteriorates
Solution Approach 1:
The patent applies equipotentiality by creating a radially uniform temperature distribution at the crystal growth interface. The cooler temperature zone where crystals form is maintained at a substantially uniform radial temperature, eliminating radial temperature gradients that would cause quality issues. This is achieved through the natural heat transfer geometry and gas flow patterns in the sealed crucible system
3Manufacturing precision
If a gas-permeable separating element is introduced to control temperature gradients, then the manufacturing precision improves, but the device complexity increases
Solution Approach 1:
The patent uses a gas-permeable separating element as an intermediary component between the source material and crystal growth zones. This element mediates heat transfer and gas flow while maintaining the temperature gradient, enabling precise growth control through a single, relatively simple structural addition to the crucible system
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, large single crystals by optimizing temperature gradients and heat flows, reducing defects and improving growth kinetics, making it suitable for crystals like SiC and AlN.
Implementation Method 1
The source material (2) preferably has a substantially cylindrical shape... Evaporation of the hot source material to form gaseous precursor material in the gas phase
Implementation Method 2
The first and/or the second surface of the gas-permeable separating element (5) is designed such that the thermal radiation emanating from the gas-permeable separating element (5), the course and intensity of the heat flows
Implementation Method 3
controlling temperature gradients... control of the heat flows within the growth pot
Implementation Method 4
Gas pressure differences are locally most pronounced along these temperature gradients. Therefore, mass transport and material flow preferably occur primarily along these temperature gradients perpendicular to the isotherms
Implementation Method 5
Deposition of the gaseous precursor material from the gas phase onto the single crystal
Implementation Method 6
crystallization at a slightly cooler location using the so-called PVT process (physical vapor transport)
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
The invention relates to a method for producing and/or growing a single crystal, and to a growth crucible for producing and/or growing a single crystal. Inside the cylindrical growth crucible are a source material, the single crystal, and a gas-permeable separating element located between the source material and the single crystal. This separating element has a first surface facing the single crystal and a second surface facing the source material. The growth crucible is designed to control temperature gradients. A temperature gradient between the source material and the single crystal is created by heating both. Gaseous precursor material is formed in the gas phase by evaporating hot source material, transported in the gas phase, and deposited from the gas phase onto the single crystal.The source material is evaporated depending on the temperature gradient, and/or the gaseous precursor material is transported and/or separated depending on the temperature gradient. The temperature gradients are set by the design of the first and/or second surface of the gas-permeable separation element and/or by changing the position of the gas-permeable separation element.