Nonthermal Plasma Silicon Compound Synthesis
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Solution Overview
Problem
Existing processes for preparing high-purity silicon compounds like hexachlorodisilane are inefficient, requiring high temperatures, significant energy expenditure, and often result in contaminated products with unwanted by-products, especially due to the use of hydrogen as a reducing agent.
Innovation Solution
A two-step process using nonthermal plasma treatment of silicon compounds without hydrogen, followed by distillative workup to isolate dimeric and trimeric silicon compounds, such as hexachlorodisilane, which achieves high and ultrahigh purity by eliminating by-products and reducing agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional chlorination processes using calcium silicide or silicon are employed, then silicon halogen compounds can be produced, but the products are contaminated with impurities from the starting materials
Solution Approach 1:
The invention extracts and removes the source of impurities by eliminating calcium silicide and metallic silicon from the process. Instead, it uses silicon tetrachloride as the sole silicon source, which can be purified to high standards. The harmful chlorination of impurities is prevented by taking out the impure starting materials and replacing them with a pure precursor.
Solution Approach 2:
The invention changes the chemical parameters of the starting material from solid calcium silicide or metallic silicon to gaseous or liquid silicon tetrachloride. This parameter change enables better control over purity and allows for more efficient chlorination reactions without introducing metal-based impurities.
2Productivity
If hydrogen is used as a reducing agent in plasma processes, then silicon compounds can be synthesized, but unwanted by-products are formed and energy consumption increases
Solution Approach 1:
The invention extracts and removes hydrogen from the reaction system. By eliminating hydrogen as a reducing agent, the source of hydrocarbon and other unwanted by-products is removed. The process achieves silicon compound synthesis without requiring hydrogen, thus preventing the formation of contaminated by-products.
Solution Approach 2:
The invention converts the harmful effect of hydrogen (causing by-product formation) into a benefit by completely eliminating its use. The process demonstrates that silicon tetrachloride can be converted to desired silicon compounds through plasma or chemical reactions without any reducing agent, turning the previously necessary but harmful hydrogen step into an unnecessary elimination.
3Productivity
If high temperatures are applied in conventional processes, then reaction efficiency improves, but energy expenditure increases significantly
Solution Approach 1:
The invention replaces thermal energy input with plasma energy input. Instead of using high-temperature thermal fields that consume significant energy, the process uses plasma (electromagnetic field with reactive species) to drive the chlorination reactions at lower temperatures, maintaining efficiency while reducing energy consumption.
Solution Approach 2:
The invention changes the energy input parameter from thermal heating to plasma activation. This allows the reaction to proceed efficiently at lower temperatures by utilizing the high reactivity of plasma-generated species rather than relying on thermal energy, thus reducing overall energy consumption while maintaining productivity.
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 process produces silicon compounds with impurities in the ppb or ppt range, suitable for semiconductor and pharmaceutical industries, without the need for hydrogen, reducing energy consumption and by-product formation.
Implementation Method 1
a nonthermal plasma treatment of a silicon compound of the general formula (IIa) is effected
Implementation Method 2
followed by distillative workup to isolate dimeric and trimeric silicon compounds
Data Source
AI summary
An apparatus for preparing dimeric and trimeric silicon compounds is provided. The apparatus includes a reactor for generating a nonthermal plasma; a collecting vessel in product flow communication with the nonthermal plasma reactor; and a series of at least three rectification columns in flow communication with the collecting vessel.