Trichlorosilane Yield via Hyper-Hydrogenated Chlorosilane Recycling
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Solution Overview
Problem
The existing processes for producing high-purity polycrystalline silicon face inefficiencies in recycling by-products like hyper-hydrogenated chlorosilane and poly-silane, which can lower the quality of the product when excessive amounts are mixed with trichlorosilane, and require improved methods for removing impurities to enhance the purity of trichlorosilane used in semiconductor-grade silicon production.
Innovation Solution
A method involving a hydrogenation step to convert tetrachlorosilane into trichlorosilane, followed by separation and circulation of hyper-hydrogenated chlorosilane, and the use of a donor/acceptor eliminator to remove electrically active impurities from the chlorosilane distillate, allowing for the recycling of low-boiling by-products and enhancing trichlorosilane production efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hyper-hydrogenated chlorosilane is recycled to the hydrogenation step, then the yield of trichlorosilane production is improved, but the purity of trichlorosilane deteriorates due to accumulation of electrically active impurities
Solution Approach 1:
The patent extracts and removes electrically active impurities (donors and acceptors) from the hyper-hydrogenated chlorosilane before recycling it to the hydrogenation step. This is achieved through a purification step that selectively removes impurities such as phosphorus, arsenic, boron, and aluminum, allowing the hyper-hydrogenated chlorosilane to be recycled without contaminating the trichlorosilane product
Solution Approach 2:
The patent discards electrically active impurities from the hyper-hydrogenated chlorosilane stream while recovering and recycling the hyper-hydrogenated chlorosilane itself back to the hydrogenation step. This selective discarding and recovering process maintains high purity trichlorosilane production while improving overall yield through by-product recycling
2Productivity
If poly-silane is converted to trichlorosilane in the hydrogenation step, then the yield of trichlorosilane is improved, but the quality of polycrystalline silicon deteriorates when excessive amounts are mixed with trichlorosilane
Solution Approach 1:
The patent controls the conversion of poly-silane to trichlorosilane by adjusting process parameters in the hydrogenation step, ensuring that poly-silane is converted to acceptable levels without excessive accumulation. This parameter control prevents quality deterioration while maintaining improved yield from poly-silane conversion
3Manufacturing precision
If a step for removing impurities is added to enhance TCS purity, then the purity of trichlorosilane is improved, but the device complexity increases
Solution Approach 1:
The patent combines the impurity removal function with the existing hyper-hydrogenated chlorosilane recycling process. The donor/acceptor eliminator is integrated into the circulation system, and the purification step is merged with the separation and recycling operations, achieving high purity without proportionally increasing overall process 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 increases the yield and purity of trichlorosilane, enabling higher efficiency in producing high-purity polycrystalline silicon by effectively recycling and purifying by-products within the production process, thereby improving the overall semiconductor-grade silicon production.
Implementation Method 1
a hydrogenation step of making a tetrachlorosilane (STC)-containing substance react with hydrogen to convert the substance into trichlorosilane (TCS)
Implementation Method 2
a step of separating chlorosilane distillate discharged in the hydrogenation step into TCS and a mixture distillate containinghyper-hydrogenated chlorosilane
Implementation Method 3
a step of removing impurities which are electrically active in a semiconductor crystal from the chlorosilane distillate discharged from the hydrogenation step
Implementation Method 4
a step of circulating TCS produced by the method for producing trichlorosilane according to the present invention to a step for depositing the polycrystalline silicon, and making the TCS react with hydrogen
Data Source
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AI summary
A hydrogenation reaction vessel (101) makes STC-containing substance react with hydrogen to convert the substance into TCS. A low boils removal column (102) separates a chlorosilane distillate discharged from a hydrogenation reaction vessel (101) into TCS and a mixture distillate containing hyper-hydrogenated chlorosilane, and circulates the mixture distillate containing hyper-hydrogenated chlorosilane to the hydrogenation reaction vessel (101). The mixture distillate containing the hyper-hydrogenated chlorosilane separated in the low boils removal column (102) is circulatingly supplied to the hydrogenation reaction vessel (101). Accordingly, low boils by-product conventionally wasted is circulated and recycled in the process, which results in enhancing a yield of TCS production.