Quartz Crucible Half-Melted Layer for Silicon Crystal Growth
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Solution Overview
Problem
Vitreous silica crucibles face issues with crystallization accelerators contaminating silicon melts or reacting with carbon at high temperatures, increasing impurity concentrations and deforming under high temperatures, and require complex manufacturing processes to prevent these issues.
Innovation Solution
A vitreous silica crucible with a bubble-containing outer surface layer and a transparent inner surface layer, featuring a half-melted silica layer with a center line average roughness of 180 to 200 µm, which crystallizes easily at high temperatures, reducing deformation and allowing for high single-crystal silicon production without the need for crystallization accelerators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a crystallization accelerator is applied to the inner surface layer of the crucible, then the crucible strength under high temperature is improved, but the crystallization accelerator comes into contact with silicon melt and increases impurity concentration
Solution Approach 1:
The crucible is divided into distinct layers: an inner transparent glass layer free of bubbles that contacts the silicon melt, and an outer layer containing bubbles and crystallization accelerators. This segmentation prevents the crystallization accelerators in the outer layer from contaminating the silicon melt while still providing high-temperature strength enhancement through controlled crystallization in the outer region.
Solution Approach 2:
The transparent inner glass layer acts as an intermediary barrier between the silicon melt and the crystallization accelerators located in the outer layer. This intermediate layer prevents direct contact between harmful substances and the molten silicon, eliminating impurity contamination while maintaining the beneficial thermal properties of the crystallization accelerators in the outer region.
2Strength
If a crystallization accelerator is applied to the outer surface layer of the crucible, then the crucible strength under high temperature is improved, but the crystallization accelerator reacts with carbon container and generates gas that lowers silicon quality
Solution Approach 1:
The outer layer is designed with a porous structure containing numerous bubbles. This porous configuration allows controlled gas permeation and prevents pressure buildup from carbon reactions, while the crystallization accelerators in this outer porous layer still provide high-temperature strength enhancement without generating harmful gases that would contaminate the silicon.
3Stability of the object's composition
If the outer layer thickness is increased to improve heat transfer uniformity, then heat distribution is improved, but the manufacturing precision and control of surface roughness become more difficult
Solution Approach 1:
The patent specifies precise parameter ranges: outer layer thickness of 0.01 to 1 mm and center line average roughness Ra of 180 to 200 µm. By defining these specific parameter boundaries, the invention balances heat transfer uniformity (achieved through adequate outer layer thickness) with manufacturing precision (maintained through controlled surface roughness specifications), enabling optimal performance without excessive complexity.
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 strength and prevents deformation under high temperatures, achieving a high single-crystallization rate for silicon while simplifying the manufacturing process and avoiding impurity contamination.
Implementation Method 1
the surface of the outer surface layer has an unmelted or half-melted silica layer (both the unmelted and half-melted ones are abbreviated as a half-melted silica layer) CC
Implementation Method 2
the crucible is easily crystallized at the outer surface layer of the vitreous silica crucible under high temperature when using the crucible
Implementation Method 3
heating the silica powder layer 11 with the arc discharge device, thereby melting the silica powder layer 11
Implementation Method 4
vacuuming is performed to remove bubbles in a glass layer by sucking air in the vitreous silica powder-deposited layer from the mold side to reduce the pressure
Data Source
AI summary
In order to provide a vitreous silica crucible which does not employ a crystallization accelerator but is difficult to deform during its use even under high temperature, and is easily manufactured, there is provided a vitreous silica crucible for pulling single-crystal silicon wherein the outer surface layer is formed of a bubble-containing vitreous silica layer, the inner surface layer is formed of a vitreous silica layer whose bubbles are invisible to the naked eye, a surface of the outer surface layer includes an unmelted or half-melted silica layer (abbreviated as a half-melted silica layer), and the center line average roughness (Ra) of the half-melted silica layer is 50 to 200 µm, also preferably, and the thickness of the half-melted silica layer is 0.5 to 2.0 mm.