Multi-Layer Quartz Crucible Structure for High-Temperature Shape Stability
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Solution Overview
Problem
Existing quartz glass crucibles used in silicon single crystal production deform and crack due to thermal expansion of bubbles during high-temperature crystal pulling, leading to reduced yield and quality issues.
Innovation Solution
A quartz glass crucible with a multi-layered structure, including an inner transparent layer, bubble layer, outer transparent layer, and transition layers with controlled bubble content, along with a crystallization accelerator-containing layer on the outer surface, to stabilize the crucible and prevent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a quartz glass crucible is used for high-temperature silicon single crystal pulling, then the crucible can melt and process silicon material, but the viscosity reduction at high temperatures causes deformation and buckling of the crucible
Solution Approach 1:
The patent applies composite material principle by creating a multi-layered crucible structure with different glass compositions. The inner layer uses high-Al2O3 content glass (3-10 wt%) for chemical stability and low bubble generation, while the outer layer uses low-Al2O3 content glass for thermal shock resistance and reduced thermal expansion. This composite structure allows the crucible to withstand high temperatures without deformation while maintaining structural integrity.
Solution Approach 2:
The patent applies local quality principle by optimizing the chemical composition and physical properties for different regions of the crucible. The inner layer is designed with specific Al2O3 content to resist silicon melt corrosion and minimize bubble formation, while the outer layer is designed with different composition to handle thermal stress and prevent cracking. Each layer has tailored properties suitable for its specific functional requirements.
2Strength
If the crucible is heated during crystal pulling, then cristobalite forms in the doped region to increase strength, but bubbles expand and cause local deformation and cracking
Solution Approach 1:
The patent applies parameter changes principle by precisely controlling the Al2O3 content parameter in different layers to prevent bubble formation and expansion. The inner layer contains 3-10 wt% Al2O3 which suppresses bubble nucleation during heating, while the outer layer has lower Al2O3 content to manage thermal expansion. This parameter optimization prevents cristobalite-related cracking and bubble expansion damage while maintaining crucible strength.
Solution Approach 2:
The patent uses composite material principle to address bubble expansion damage by combining glass compositions with different thermal and mechanical properties. The multi-layered structure with controlled Al2O3 distribution creates a composite system that resists bubble formation in the inner layer while managing thermal stress in the outer layer, preventing local deformation and cracking during heating.
3Shape
If a multi-layered structure with transition layers is used, then bubble content is controlled to prevent deformation, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies segmentation principle by dividing the crucible wall into multiple functional layers with distinct compositions and properties. The inner layer, outer layer, and transition layers are segmented to control bubble content and thermal stress distribution. This segmentation allows precise control of shape stability by managing bubble formation in each layer while providing a systematic approach to manufacturing through defined composition gradients.
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 crucible maintains a stable shape during long-duration use, preventing deformation and increasing the yield of high-quality silicon single crystals.
Implementation Method 1
an outer surface layer portion of the crucible main body is doped with a crystallization accelerator... when the crucible is heated during the pulling of crystal, the outer surface of the crucible main body is positively crystallized... cristobalite is formed in the doped region to accelerate the crystallization of the quartz glass
Implementation Method 2
the viscosity is reduced at high temperatures of 1400° C. or higher when pulling up the silicon single crystal, and thus the initial shape thereof cannot be maintained and deformation of the crucible such as buckling or inward collapse occurs
Data Source
AI summary
A quartz glass crucible has, from an inner surface side toward an outer surface side of the crucible, an inner transparent layer, a bubble layer, an outer transparent layer, and a crystallization accelerator-containing layer. An outer transition layer where a bubble content decreases from the bubble layer toward the outer transparent layer is provided at a boundary between the bubble layer and the outer transparent layer, and a thickness of the outer transition layer is 0.1 mm or more and 8 mm or less.