Quartz Crucible Fictive Temperature Gradient Inward Deformation
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Solution Overview
Problem
Conventional quartz glass crucibles used for pulling silicon single crystals face deformation issues due to heat load, leading to the straight body part falling inwards, which is costly to address with existing methods that affect crystal quality.
Innovation Solution
A quartz glass crucible with a fictive temperature gradient across its thickness, where the outermost temperature is at least 50°C lower than the innermost, is produced by fusing the crucible and maintaining the outer temperature while cooling the inner surface, using a mould and residual powder to control thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the straight body part is increased to prevent deformation, then the structural strength is improved, but the crystal quality may be affected and the device complexity increases
Solution Approach 1:
The patent applies parameter changes by creating a fictive temperature gradient within the quartz glass material itself. Instead of changing the geometric thickness parameter, the invention modifies the thermal parameter (fictive temperature distribution) to achieve the desired mechanical property (deformation resistance) while maintaining original dimensions that preserve crystal quality.
Solution Approach 2:
The patent implements local quality by creating a non-uniform fictive temperature distribution within the crucible wall thickness. The inner surface has a different fictive temperature than the outer surface, giving different thermal expansion characteristics to different regions of the same component, thereby preventing deformation without increasing overall thickness.
2Stability of the object's composition
If conventional methods such as glass surface crystallization or embedding annular members are used to prevent deformation, then the deformation resistance is improved, but the manufacturing cost increases significantly
Solution Approach 1:
The patent changes the thermal parameter (fictive temperature) distribution within the existing quartz glass structure to achieve deformation resistance. This avoids the need for additional manufacturing steps like surface crystallization or embedding annular members, thereby maintaining ease of manufacture while improving stability.
Solution Approach 2:
The patent enables the crucible to prevent its own deformation through internally generated fictive temperature gradients. The structure serves itself by utilizing the thermal history and expansion characteristics of the quartz glass material rather than requiring external reinforcement structures or complex surface treatments.
3Ease of manufacture
If the outer layer containing cells is used in the crucible configuration, then the manufacturing process is simplified, but the heat load causes differential expansion and leads to inward deformation of the straight body part
Solution Approach 1:
The patent applies local quality by creating a fictive temperature gradient within the outer layer material. Different regions of the outer layer (inner surface vs outer surface) have different fictive temperatures, resulting in differential thermal expansion that compensates for the inherent expansion tendency of the cellular structure, thereby maintaining shape stability.
Solution Approach 2:
The patent utilizes thermal expansion principles by controlling the fictive temperature distribution to manage differential expansion between the inner and outer surfaces. The fictive temperature gradient creates controlled expansion characteristics that prevent the straight body part from deforming inward under heat load.
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 configuration effectively prevents the crucible from falling inwards by balancing thermal expansion and density differences, ensuring stable crystal growth without compromising crystal quality.
Implementation Method 1
the outer layer which contains cells is more likely to expand than the inner layer due to the heat load when the single crystal is pulled, and the straight body part which is not pressed by the silicon melt falls inwards due to this expansion differential
Implementation Method 2
a cooling system that cools the inner surface of the crucible
Data Source
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AI summary
A quartz glass crucible for silicon single crystal pulling operation that by a simple arrangement, attains prevention of any collapse onto the inside at a superior edge of straight trunk part; and a process for manufacturing the same. The quartz glass crucible for silicon single crystal pulling operation having a straight trunk part and a bottom part, is characterized in that at least the straight trunk part is provided with a gradient of fictive temperature so that the fictive temperature on the outermost side thereof is 25°C or more lower than the fictive temperature on the innermost side thereof.