Trichlorosilane Purity via Hyper-Chlorination and Distillation
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Solution Overview
Problem
Conventional methods for producing high-purity polycrystalline silicon face challenges in enhancing the purity and yield of trichlorosilane (TCS) due to impurities and by-product recycling inefficiencies in the semiconductor-grade production process.
Innovation Solution
A method involving a hydrogenation step to convert tetrachlorosilane (STC) to TCS, followed by separation into chlorosilane and TCS fractions, and a chlorination step to purify the chlorosilane fraction using chlorine, with the effluent being recycled, along with impurity removal to enhance TCS purity and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional Siemens method is used to produce high-purity polycrystalline silicon, then polycrystalline silicon of semiconductor grade can be obtained, but the purity and yield of TCS are limited due to impurity accumulation and inefficient by-product recycling
Solution Approach 1:
The invention divides the by-product mixture into multiple fractions through distillation separation (TCS fraction, chlorosilane fraction, and other fractions), allowing selective processing and purification of each component to enhance both purity and yield
Solution Approach 2:
The invention recovers valuable TCS and chlorosilanes from the by-product mixture through systematic distillation and chemical conversion, transforming waste streams into reusable raw materials that enhance overall process yield
2Productivity
If by-product mixture is recycled to enhance yield, then more TCS can be produced, but impurity accumulation reduces TCS purity
Solution Approach 1:
The invention extracts and removes impurities (carbon contaminants, metal impurities, and unwanted by-products) from the recycled by-product mixture through distillation separation and chemical treatment, allowing high-purity TCS to be obtained while maintaining high yield
Solution Approach 2:
The invention changes the chemical parameters of the by-product mixture through controlled chemical reactions (such as chlorination of hydrocarbons) to convert impurities into removable forms, thereby enhancing purity while preserving yield
3Manufacturing precision
If separation and purification steps are added to increase TCS purity, then semiconductor-grade silicon can be produced, but process complexity increases
Solution Approach 1:
The invention combines multiple functions into integrated process units, such as combining distillation separation with chemical conversion steps, to achieve high purification efficiency while minimizing the number of separate equipment units and operational 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
This method effectively increases the purity of TCS, reduces carbon contamination in polycrystalline silicon, and improves the overall efficiency of the production process by recycling high-purity TCS and minimizing external chlorosilane discharge.
Implementation Method 1
a hydrogenation step of making tetrachlorosilane (STC) react with hydrogen into trichlorosilane (TCS)
Implementation Method 2
a step of separating an effluent from the hydrogenation step into a chlorosilane fraction containing a hydrocarbon and a TCS fraction
Implementation Method 3
a chlorination step of making the chlorosilane fraction containing the hydrocarbon produced in the separation step react with chlorine to form STC and a substance containing a chlorinated hydrocarbon
Data Source
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AI summary
The present invention includes a step of separating an effluent produced in a hydrogenation step of making tetrachlorosilane (STC) react with hydrogen into trichlorosilane (TCS), into a chlorosilane fraction containing a hydrocarbon and a TCS fraction, and a chlorination step of making the chlorosilane fraction containing the hydrocarbon react with chlorine to form STC and a substance containing a chlorinated hydrocarbon, wherein the effluent containing STC produced in the chlorination step is circulated to the hydrogenation step. In the chlorination step, the chlorosilane fraction containing a hydrocarbon (capable of containing hyper-hydrogenated chlorosilanes) having a boiling point close to TCS is hyper-chlorinated to be converted and acquire a higher boiling point, which facilitates the hyper-chlorinated chlorosilanes and the hyper-chlorinated hydrocarbons to be separated into high concentration, and increases the purity of TCS to be finally obtained.