Crystal Growth Apparatus with Reflection Plate for Uniform Composition
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Solution Overview
Problem
Conventional methods for producing crystals, such as the Vertical Bridgman Method and vertical gradient freeze method, face challenges in maintaining uniform crystal composition and quality due to variations in crystal growth rate and dopant segregation, leading to inconsistent crystal properties and reduced productivity.
Innovation Solution
A method and apparatus where a crucible is maintained with a temperature gradient, and a resupply raw material is added as a liquid at the same temperature as the initial liquefied material, using a reflection plate to ensure consistent composition and quality by providing a soaking treatment, thereby stabilizing the crystal growth process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If temperature regulation is applied to control crystal diameter in conventional methods, then crystal growth amount can be controlled, but crystal quality varies due to growth rate changes at different sites
Solution Approach 1:
The patent changes the temperature parameter distribution by introducing a temperature gradient in the vertical direction, with the lower portion at crystallization temperature and the upper portion at higher temperature. This parameter change eliminates the need for continuous temperature regulation during growth, maintaining uniform crystal quality while controlling diameter through the gradient structure.
Solution Approach 2:
The patent creates an equipotential temperature zone in the upper portion of the crucible where the temperature is maintained above the crystallization temperature. This equipotential hot zone ensures uniform thermal conditions for the growing crystal, preventing quality variations that would occur with active temperature regulation.
2Manufacturing precision
If dopant concentration is maintained in the raw material during crystal growth, then initial composition can be controlled, but dopant segregation causes composition variation in the crystal
Solution Approach 1:
The patent applies preliminary action by performing a soaking treatment on the raw material before crystal growth begins. The raw material is heated to a temperature higher than the crystallization temperature to achieve uniform dopant distribution throughout the molten material. This preliminary action prevents dopant segregation during subsequent crystal growth, ensuring composition uniformity.
Solution Approach 2:
The patent changes the temperature parameter by maintaining the upper crucible zone above crystallization temperature, creating a soaking zone. This parameter change allows the raw material to achieve uniform dopant distribution before crystallization begins, preventing segregation issues that would occur with conventional temperature maintenance.
3Stability of the object's composition
If resupply raw material is added during crystal growth to maintain composition, then composition change can be corrected, but crystal quality deteriorates due to temperature variation
Solution Approach 1:
The patent applies preliminary action by pre-heating the resupply raw material to the soaking temperature (higher than crystallization temperature) before adding it to the crucible. This preliminary heating ensures that the resupply material integrates uniformly without causing temperature shocks or quality deterioration, while still maintaining composition consistency.
Solution Approach 2:
The patent uses the upper temperature zone as an intermediary soaking zone where resupply raw material is pre-heated and prepared before being incorporated into the crystal growth process. This intermediary zone acts as a buffer that prevents direct temperature shocks to the growing crystal, maintaining quality while enabling composition control.
4Productivity
If conventional Vertical Bridgman Method or vertical gradient freeze method is used, then crystal growth can proceed with constant rate, but productivity is reduced due to composition variation and quality issues
Solution Approach 1:
The patent changes the temperature parameter distribution by creating a vertical gradient with the lower portion at crystallization temperature and the upper portion at soaking temperature. This parameter change enables constant growth rate operation while preventing composition variation and quality issues, thereby improving productivity without sacrificing reliability.
Solution Approach 2:
The patent segments the crucible temperature field into two distinct zones: a lower crystallization zone at crystallization temperature and an upper soaking zone at higher temperature. This segmentation allows independent optimization of each zone - the lower zone maintains constant growth rate while the upper zone ensures composition uniformity and quality, resolving the productivity-reliability contradiction.
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 ensures uniform crystal quality and composition throughout the growth process, reducing variations and polycrystallization, and maintaining a consistent crystal composition, thereby improving the yield and quality of the produced crystals.
Implementation Method 1
A crystal-producing furnace has the temperature distribution 5 in which the lower portion of the crucible 1 is a lower temperature area than the crystallization temperature and the upper portion of the crucible 1 is a higher temperature area than the crystallization temperature
Implementation Method 2
Crystals 3 which have reached the crystallization temperature are grown to crystals using seed crystal 4 as nuclei
Implementation Method 3
a resupply raw material supplied from a raw material supply apparatus placed above the crucible is supplied by heating to the same temperature as in the higher temperature area
Data Source
AI summary
A method and an apparatus for producing crystals wherein crystal quality can be kept and a crystal composition is uniformed from a growth early stage to a growth last stage are provided. In an apparatus for producing crystals wherein the crystals 13 are grown from a liquefying raw material 12 in a crucible retained in a furnace and slowly cooling the raw material 12 in the crucible 11 from below upward, the apparatus comprises a raw material supply apparatus 18 which supplies a resupply raw material, and a reflection plate 20 placed above the crucible 11, which liquefies the resupply raw material 19 supplied from the raw material supply apparatus 18 and drops it as a liquid into the crucible.