Closed-Loop Silicon Production Reducing Tetrachloride Waste
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Solution Overview
Problem
Current methods for producing high-purity silicon, such as the Siemens process, are energy-intensive and generate significant silicon tetrachloride by-products, with existing improvements still producing substantial amounts of waste.
Innovation Solution
A method involving the reaction of gaseous trichlorosilane with hydrogen to deposit silicon, vaporizing and converting silicon tetrachloride by-products into finely divided silicon, which is then melted and formed into solid silicon, reducing impurities and by-product generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the Siemens process is used to produce high-purity silicon from trichlorosilane, then high-purity silicon can be obtained, but the process is highly energy-consuming and creates three to four moles of silicon tetrachloride by-product for every mole of obtained silicon
Solution Approach 1:
The patent changes the temperature parameter during pyrolysis to higher temperatures (above 1000°C) to alter the reaction pathway and reduce silicon tetrachloride formation, while maintaining silicon purity through controlled deposition conditions
Solution Approach 2:
The patent recovers and reuses silicon tetrachloride by-product by reducing it back to trichlorosilane, which is then re-introduced into the system, thereby minimizing waste and reducing energy consumption through material recycling
2Loss of substance
If the pyrolysis temperature is increased to reduce silicon tetrachloride by-product, then the amount of by-product is diminished, but the process still produces one-third to one-half that produced under original Siemens process conditions
Solution Approach 1:
The patent converts the harmful silicon tetrachloride by-product into a useful resource by reducing it back to trichlorosilane, which serves as feedstock for continued silicon production, thereby eliminating waste and improving overall process efficiency
Solution Approach 2:
The patent implements a feedback loop where silicon tetrachloride by-product is reduced to trichlorosilane and re-introduced into the reaction system, allowing continuous optimization of the process to minimize by-product formation while maintaining high silicon production efficiency
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 process efficiently produces high-purity silicon with reduced by-products, achieving desired impurity levels for semiconductor and solar cell applications while minimizing energy consumption.
Implementation Method 1
reacting the gaseous trichlorosilane with hydrogen in the presence of a substrate at a temperature to cause the deposition of silicon onto the substrate and the production of silicon tetrachloride by-product
Implementation Method 2
vaporizing the silicon tetrachloride by-product to form gaseous silicon tetrachloride
Implementation Method 3
converting the gaseous silicon tetrachloride to finely divided silicon having an average primary particle size of about 200 nm or less and an average agglomerate size of about 500 μm or more
Implementation Method 4
forming a silicon melt by melting the finely divided silicon
Data Source
AI summary
The inventive method of producing silicon comprises reacting gaseous trichlorosilane with hydrogen to deposit silicon onto a substrate and to produce silicon tetrachloride by-product, vaporizing the silicon tetrachloride by-product to form gaseous silicon tetrachloride, converting the gaseous silicon tetrachloride to finely divided silicon, forming a silicon melt by melting the finely divided silicon, and forming solid silicon from the silicon melt.