Directional Solidification Mold System for High-Purity Silicon
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Solution Overview
Problem
Existing silicon purification techniques for solar cells, such as the Siemens process and directional solidification, are costly and inefficient in removing impurities, particularly due to the need for complex equipment and high energy consumption.
Innovation Solution
A directional solidification mold system with a controlled temperature gradient, utilizing a composite wall insulation structure and heat conducting layers to manage the solidification process, allowing for precise control of the liquid-solid interface and impurity segregation, thereby reducing costs and improving purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the Siemens process is used to purify silicon, then high purity silicon is achieved, but the process requires complex equipment and high energy consumption
Solution Approach 1:
The patent changes the physical state parameters of silicon during purification - melting silicon to liquid phase and controlling directional solidification, rather than using the gas-phase deposition of Siemens process. This parameter change simplifies equipment requirements while maintaining purification effectiveness
Solution Approach 2:
The patent utilizes phase transition between liquid and solid states of silicon through controlled directional solidification. By managing the solidification process from a molten silicon solution, impurities are segregated and removed, achieving high purity without the complex gas-phase equipment of Siemens process
2Manufacturing precision
If directional solidification is used to purify silicon, then impurities are removed effectively, but the process requires controlled temperature gradients and longer processing time
Solution Approach 1:
The patent performs preliminary melting of silicon to create a homogeneous molten solution before directional solidification. This preliminary action ensures uniform composition and facilitates faster, more efficient impurity segregation during the subsequent solidification process
Solution Approach 2:
The patent maintains continuous controlled cooling through the mold during directional solidification, ensuring uninterrupted heat extraction and consistent temperature gradient. This continuous action accelerates the solidification process while maintaining purification effectiveness
3Manufacturing precision
If conventional directional solidification is used, then silicon purification is achieved, but the production cost remains high
Solution Approach 1:
The patent employs a simple, disposable mold design that can be easily manufactured and replaced. The mold uses basic insulation materials and heat conducting layers that are cost-effective, eliminating the need for expensive, complex equipment required by conventional directional solidification processes
Solution Approach 2:
The system uses the natural thermal properties of materials and the inherent directional solidification behavior of silicon to achieve purification. The process relies on self-organizing phase transition and impurity segregation during cooling, minimizing the need for complex external control systems and reducing manufacturing costs
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 system achieves high-purity silicon production with reduced costs by efficiently controlling the temperature gradient and solidification rate, enabling the production of higher purity silicon for solar cells with fewer processing steps and larger ingot sizes.
Implementation Method 1
at least one heat conducting layer lining a bottom of the outer mold jacket
Implementation Method 2
at least one insulation layer lining a wall of the outer mold jacket
Implementation Method 3
directional solidification of silicon, while maintaining a consistent progression of a liquid-solid interface throughout the mold
Implementation Method 4
solidifying the Silicon using a technique called directional solidification
Data Source
AI summary
The present invention relates to an apparatus and method for purifying materials using a rapid directional solidification. Devices and methods shown provide control over a temperature gradient and cooling rate during directional solidification, which results in a material of higher purity. The apparatus and methods of the present invention can be used to make silicon material for use in solar applications such as solar cells.