Cylinder Assembly Axial Temperature Gradient Control
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Solution Overview
Problem
The existing heat shield designs in single crystal pulling apparatuses fail to effectively adjust the axial temperature gradient of crystal ingots, leading to an increased gradient difference between the edge and center, which results in the aggregation of vacancy defects and reduces the defect-free growth region.
Innovation Solution
A cylinder assembly comprising an inner and outer graphite cylinder, a molybdenum annular plate, and a quartz sleeve with thermally conductive and insulating fillers, which ensures a stable inert gas flow and heat transfer to reduce the axial temperature gradient difference, facilitating defect-free growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional heat shield is used in the Hot-Zone, then the structure is simple, but the axial temperature gradient at the edge decreases and the gradient difference ΔG increases, leading to vacancy defect aggregation
Solution Approach 1:
The heat shield is divided into multiple segments: an upper heat shield and a lower heat shield separated by a distance, with the inner cylinder positioned between them. This segmentation allows independent optimization of temperature gradients at different locations, enabling precise control of the axial temperature gradient difference ΔG while maintaining structural simplicity
Solution Approach 2:
The inner cylinder acts as an intermediary component between the upper and lower heat shields. It mediates heat distribution to achieve a balanced axial temperature gradient, preventing excessive gradient difference that would cause vacancy defect aggregation while maintaining overall structural simplicity
2Productivity
If heat is transferred from melt surface to crystal ingot surface, then the crystal ingot grows, but the axial temperature gradient at the edge decreases, increasing ΔG and reducing defect-free growth region
Solution Approach 1:
The patent applies different thermal characteristics to different regions: the upper heat shield provides stronger heating to maintain overall growth temperature, while the lower heat shield and inner cylinder configuration creates a more gradual temperature gradient at the edge. This local quality differentiation enables continuous crystal growth while maintaining optimal axial temperature gradient distribution to prevent vacancy defects
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 solution stabilizes the solid-liquid-gas triple point, reduces the axial temperature gradient difference, and enhances the defect-free growth region of the crystal ingot, producing high-quality crystals by maintaining a stable temperature field and efficient heat transfer.
Implementation Method 1
The first filler is made of thermally conductive material
Implementation Method 2
The second filler is made of thermally insulating material
Data Source
AI summary
A cylinder assembly of a single crystal pulling apparatus and a single crystal pulling apparatus are provided in the present disclosure. The cylinder assembly includes an inner cylinder, an outer cylinder, an annular plate and a sleeve. The inner cylinder has a shape of inverted conical. An upper end of the inner cylinder is connected to an upper end of the outer cylinder. A lower end of the outer cylinder is hermetically connected to an outer edge of the annular plate. A lower end of the inner cylinder is fixedly connected to an upper surface of the annular plate. The sleeve passes through and is fixed in an annular opening of the annular plate.