Device and method for preparing trichlorosilane from silicon tetrachloride

Abstract

The invention discloses a device and a method for preparing trichlorosilane from silicon tetrachloride. The device comprises sealing flanges, variable backing rings, high-voltage baffle rings, an electric medium, an outer electrode and an inner electrode, wherein the inner electrode is positioned at the position of an axis; two ends of the inner electrode are respectively connected with the two sealing flanges; two ends of the electric medium are respectively connected with the two sealing flanges; the inner electrode is sleeved by the electric medium; the electric medium is sleeved by the high-voltage baffle rings; the high-voltage baffle rings are tightly adhered to the sealing flanges; the outer surface of the electric medium is tightly wrapped by the outer electrode; an air inlet guide hole is formed in one sealing flange; an air outlet guide hole is formed in the other sealing flange. The device is flexible in structure and good in air tightness, geometrical parameters of the device can be easily adjusted, and damage caused by air leakage can be eliminated; breakdown voltage can be effectively reduced, plasma can be maintained in an unbalance state, low-temperature plasma can be easily generated, and the electron density inside a discharge gap can be effectively increased; the device is wide in operation range, and can work with relatively high air pressure, voltage, frequency and power.

Description

technical field [0001] The invention relates to the technical field of polysilicon preparation, in particular to a device and method for preparing trichlorosilane from silicon tetrachloride. Background technique [0002] With the rapid development of global industrialization, the demand for energy is increasing day by day. However, traditional petroleum energy is gradually exhausted and has many disadvantages, such as: limited storage, mining will cause great harm to the environment, and combustion products contain a large amount of harmful substances, etc. Traditional energy can no longer meet the development and requirements of today's industries. Therefore, it is imminent to explore an efficient and feasible alternative energy source. Among many energy alternatives, solar energy has become a current research hotspot due to its green, peaceful, safe, and abundant reserves, and is expected to become the main energy source of the next generation. [0003] Polysilicon is the...

AI Technical Summary

Problems solved by technology

[0006] 1. The airtightness of the plasma reactor is poor, and the leakage of hydrogen and chlorosilane gas will cause huge safety hazards;

[0007] 2. The plasma in the discharge gap of the reactor is easy to become thermal quasi-equilibrium plasma (such as the silicon tetrachloride plasma hydrogenation process driven by direct current, the optimum reaction temperature is 3000-4500K)

In thermal quasi-equilibrium plasma, the temperatures of electrons, ions and neutral particles are approximately equal. Therefore, heavy particles with higher energy will hit the electrode at a higher frequency, which will not only wear out the electrode, but also need to cool down the high-temperature electrode, increasing the temperature of the electrode. extra cost;

[0008] 3. The design of the reactor is unreasonable, and the geometric parameters of the reactor cannot be changed, especially the discharge gap cannot be adjusted, which means that multiple reactors with different parameters need to be equipped in the experiment. The experimental error caused by the reactor will also increase the cost of the experiment. In addition, the above-mentioned reactors also have problems such as difficult cleaning and maintenance;

[0009] 4. The silicon tetrachloride plasma hydrogenation process with direct current, microwave, and radio frequency as the driving energy has a high yield of trichlorosilane, up to 60%, but the above-mentioned hydrogenation process has high investment costs and large side effects (using radio frequency The high-frequency current represented by the high-frequency current will generate large electromagnetic radiation, which is harmful to the human body and the environment), the plasma flame is short, and the energy consumption has no obvious advantages compared with the thermal hydrogenation process. The above shortcomings seriously restrict the above-mentioned plasma hydrogenation process. Further development;

[0010] 5. The plasma reactor currently used mostly adopts the form of flat bare electrode. The above-mentioned flat flat electrode plasma reactor has a high initial breakdown voltage and a narrow voltage adjustable range. When the voltage exceeds the limit voltage, the discharge in the gap It is very easy to convert into arc discharge. The above shortcomings limit the development of flat plate bare electrode reactors in industrial applications with high pressure and high power discharge characteristics;

[0011] 6. The electrode material and shape have an important influence on the occurrence of plasma and its temporal and spatial evolution. At present, most of the electrode materials used are stainless steel or copper, and their surfaces are mostly smooth or needle-shaped. The surface electrons of stainless steel or copper electrodes The work function is high, which is not conducive to the emission of secondary electrons. The plasma reactor based on smooth electrodes has a high initial breakdown voltage and is easy to evolve into an arc discharge. Although the needle-shaped electrode can have an initial breakdown voltage, the The effective particle contact area is small, and the production cost is high

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