Triaxial Carbon-Fiber Crucible Holder for Thermal Expansion Cracking
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Solution Overview
Problem
Large-size graphite crucibles used in silicon single crystal pulling apparatuses face challenges with handling and cracking due to thermal expansion differences between the crucible and quartz crucible, leading to silicon melt leakage and damage during the crystal pulling process.
Innovation Solution
A container holding member with a triaxial weave mesh body formed by bundling carbon fibers is developed, where strands are aligned diagonally to absorb circumferential expansion, providing high strength and shape stability while allowing for adjustable rigidity, preventing crack formation and melt leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the diameter of the graphite crucible is increased to support larger silicon wafers, then the productivity and yield are improved, but the weight of the graphite crucible becomes extremely heavy, making handling and setting difficult
Solution Approach 1:
The graphite crucible is divided into multiple segments that can be assembled together. Each segment has a manageable weight for handling, but when assembled, they form a large-diameter crucible capable of supporting bigger silicon wafers, thus maintaining productivity while solving the weight issue.
Solution Approach 2:
Multiple graphite crucible segments are nested or stacked together to form the complete large-diameter crucible. This allows the crucible to be transported and handled in smaller, manageable pieces that can be easily assembled on-site, reducing handling difficulty while achieving the required size for high productivity.
2Stability of the object's composition
If the coefficient of thermal expansion difference between graphite crucible and quartz crucible is considered, then shape stability is improved, but circumferential tension causes cracking in the graphite crucible
Solution Approach 1:
The graphite crucible is designed with non-uniform thickness or material properties in different regions. The circumferential regions have enhanced strength or flexibility to accommodate thermal expansion differences, while maintaining overall shape stability. This local adaptation prevents cracking under thermal stress while preserving the required geometric stability.
Solution Approach 2:
The graphite crucible incorporates composite material structures or reinforcement elements that provide both shape stability and crack resistance. By combining materials with different thermal and mechanical properties, the crucible can withstand circumferential tension from thermal expansion differences without cracking, while maintaining its required shape for proper function.
3Manufacturing precision
If a CIP apparatus is used to produce large-size isotropic graphite material, then the manufacturing precision is improved, but the apparatus size becomes about 1.5 times the diameter of the graphite product, requiring larger equipment
Solution Approach 1:
The graphite crucible is produced in segmented form using smaller, more manageable equipment. Each segment can be manufactured with adequate density uniformity using standard-sized CIP apparatus, and then assembled into the complete large-diameter crucible. This avoids the need for oversized equipment while maintaining manufacturing precision through controlled segment production.
Solution Approach 2:
The graphite material is pre-formed into segments with controlled density and shape before final assembly. This preliminary formation allows the use of smaller, standard equipment to achieve the required manufacturing precision, and the pre-formed segments are then assembled into the final large-diameter crucible configuration, avoiding the need for large-scale equipment.
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
The triaxial weave container holding member effectively maintains shape stability and prevents cracking, even under circumferential tension, ensuring reliable operation and reducing damage from silicon melt expansion during the crystal pulling process.
Implementation Method 1
The coefficient of thermal expansion of quartz glass is 0.6×10^-6... However, when the silicon melt coagulates... silicon has the property of expending (a volume expansion of about 9.6%) with coagulation. This acts as the function of enlarging the quartz crucible and the graphite crucible.
Data Source
Figure 1A~1B
Figure 2
Figure 3(a)~3(d)
AI summary
A container holding member for holding a container for containing a high-temperature melt is provided. The container holding member includes: a basket-like mesh body having a closed-end and formed by weaving a plurality of strands to be aligned diagonally to a central axis of the mesh body, each of the strands including a plurality of carbon fibers; and a matrix filled in the interstices between the carbon fibers.