Method for synthesizing and refining electronic-grade hexachloroethyldisilane

Abstract

The application relates to a method for synthesizing and refining electronic-grade hexachloroethyldisilane, and specifically, trichlorosilane raw material is mixed with protective gas into a raw material buffer tank, a mixed gas obtained through the mixing is subjected to a catalytic synthesis reaction under the irradiation of an ultraviolet light source, a product obtained through the reaction is subjected to condensation separation, gaseous trichloromethane returns to the raw material buffer tank to continuously participate in the synthesis reaction, the mixed liquid in the cold trap is warmed and vaporized, hexachloroethyldisilane is obtained through two-step refining, and the purity of the product hexachloroethyldisilane can reach the electronic grade. The application takes trichlorosilane as the initial raw material, the price of the raw material is low; the photo-catalysis is used as the synthesis process, the synthesis process is simple, the reaction yield is high, energy is saved, and the environment is protected; the two-step method is used for refining and purifying the product, the depth of the refining and the efficiency of the refining are high, large-scale production is suitable, the monopoly of foreign enterprises is broken, and the application has important significance.

Description

Technical Field

[0001] This invention relates to the field of hexachlorosilane production and application technology, specifically to a method for synthesizing and purifying electronic-grade hexachlorosilane. Background Technology

[0002] High-purity electronic-grade hexachlorosilane is a stable, low-volatility, humidity-sensitive specialty gas with wide applications in the semiconductor industry. It is primarily used for the preparation of thin films such as silicon oxide and silicon nitride films. Compared to traditional chemical vapor deposition (CVD) methods for preparing silicon oxide and silicon nitride films, the hexachlorosilane method offers advantages such as lower deposition temperature, lower deposition pressure, and higher production efficiency. Furthermore, the resulting silicon oxide and silicon nitride films exhibit better density, insulation, corrosion resistance, and compatibility. Researchers have used hexachlorosilane and germane in reduced-pressure CVD equipment to grow Si and SiGe layers at process temperatures of 500°C or even lower, demonstrating that the partial pressure of hexachlorosilane is beneficial for increasing the growth rate of Si layers and can lower the Si layer growth temperature threshold from 475°C to 460°C.

[0003] Currently, the synthesis methods for hexachlorosilane include the silicon powder-silicon tetrachloride method, the chlorosilane synthesis method, and the silicon or silicon alloy chlorination synthesis method. The silicon powder method has the advantage of cheap raw materials, but its low selectivity and expensive catalysts limit its development. Chlorosilane also has the advantage of cheap raw materials, but chlorosilane is generally produced by recovering polycrystalline silicon residues, resulting in unstable raw material sources and making large-scale production impossible. The silicon or silicon alloy method produces products with metal contamination, and the separation process is more complicated. Summary of the Invention

[0004] This invention provides a method for synthesizing and purifying electronic-grade hexachlorosilane, which reduces raw material and catalyst costs, simplifies the production process, and improves the purity of the product hexachlorosilane.

[0005] The technical solution of the present invention:

[0006] A method for synthesizing and purifying electronic-grade hexachlorosilane, characterized in that: trichlorosilane or photocatalytically recovered trichlorosilane raw materials are mixed with a protective gas in a raw material buffer tank, the mixed gas enters a photocatalytic reactor, and under the action of an ultraviolet light source, catalytic synthesis is carried out to obtain a mixed gas containing hexachlorosilane, trichloromethane and propane. The obtained mixed gas passes through a condenser, and under the action of a refrigerant, the gaseous trichloromethane is recovered to the raw material buffer tank to continue to participate in the catalytic synthesis reaction. The mixed liquid of hexachlorosilane and trichloromethane enters a cold trap, and the mixed liquid in the cold trap is heated and vaporized, and then subjected to a two-step purification process of removing light and heavy components to obtain hexachlorosilane.

[0007] Preferably, the trichlorosilane raw material has a purity greater than 99.9%, and the protective gas is helium or argon;

[0008] Preferably, the flow rate of the trichlorosilane feedstock is 500 mL to 800 mL per minute, and the flow rate of the protective gas is 50 mL to 80 mL per minute;

[0009] Preferably, the wavelength range of the ultraviolet light source is 360nm to 400nm;

[0010] Preferably, the catalytic synthesis is carried out in a photocatalytic reactor at a reaction pressure of 0.5 MPa to 1.5 MPa and a reaction temperature of 10°C to 60°C.

[0011] Preferably, the conditions for condensing the mixed gas are: refrigerant temperature of -20℃ to -35℃, pressure of 0.3MPa to 0.5MPa, and gas flow rate of 300mL to 600mL per minute;

[0012] Preferably, the two-step refining process consists of removing light and heavy components.

[0013] The conditions for removing light components are: gas flow rate of 300 mL to 600 mL per minute, refrigerant temperature of -20°C to -35°C, distillation pressure of 0.4 MPa to 0.8 MPa, and distillation temperature of -5°C to 20°C. The light components removed are hydrogen, oxygen, nitrogen, and trichlorosilane.

[0014] The conditions for removing heavy components are: an airflow rate of 300 mL to 600 mL per minute, a refrigerant temperature of -20°C to -35°C, a distillation pressure of 0.1 MPa to 0.4 MPa, and a distillation temperature of -10°C to 5°C. The heavy components removed include high-silane and water, etc. Preferably, the refrigerant used for condensation separation, removal of light components, and removal of heavy components is dichloromethane or ethylene glycol.

[0015] Preferably, the hexachlorosilane obtained after removing light and heavy components has a purity of electronic grade (6N).

[0016] The beneficial effects of this invention:

[0017] The method proposed in this invention for preparing hexachlorosilane has several advantages: first, the raw materials are inexpensive, which can significantly reduce product costs compared to traditional reduction methods; second, the use of ultraviolet light irradiation provides mild conditions and saves energy; third, the process route is simple, the product conversion rate is high, and it can be mass-produced industrially; and fourth, the two-step purification process results in a product with higher purity. Attached Figure Description

[0018] Figure 1 This is a flow chart of the hexachlorosilane production process. Detailed Implementation

[0019] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0020] Examples 1-5

[0021] As shown in Tables 1, 2, and 3, the main difference between Examples 1 to 5 is that the process parameters for preparing ethylsilane are different, and the purity of the trichlorosilane raw material in Examples 1 to 5 is 99.9%.

[0022] Examples 1-5 provide a method for the synthesis and purification of electronic-grade hexachlorosilane as follows:

[0023] Trichlorosilane feedstock and protective gas are introduced into a feedstock buffer tank, with the trichlorosilane feedstock gas flow rate at 500–800 mL / min and the protective gas flow rate at 50–80 mL / min. The mixed gas in the feedstock buffer tank enters the photocatalytic reactor BL-GHX-V for photocatalytic reaction. The ultraviolet light source wavelength is 360–400 nm, the reaction pressure is 0.5–1.5 MPa, and the reaction temperature is 10℃–60℃, resulting in a mixed gas containing hexachlorosilane. The resulting mixed gas is then introduced into a condenser. Under refrigerant conditions, the hexachlorosilane and propane in the mixed gas are condensed into a cold trap. The refrigerant dichloromethane has a temperature of -20 to -35℃, a pressure of 0.3–0.5 MPa, and a gas flow rate of 300 mL–600 mL / min. The gaseous trichlorosilane is discharged from the cold trap and returned to the feedstock buffer tank to continue participating in the photocatalytic reaction. The mixture containing hexachlorosilane enters the cold trap; the mixture is vaporized by heating and enters the buffer tank, and then enters the distillation column from the buffer tank for the removal of light and heavy components;

[0024] The hexachlorosilane mixture in the buffer tank first enters the light component removal tower to remove the light components from the silane. The gas flow rate is 300 mL to 600 mL per minute, the distillation pressure is 0.4 MPa to 0.8 MPa, and the distillation temperature is -5℃ to 20℃.

[0025] The light components removed from the hexachlorosilane are then introduced into a heavy components removal column to remove the heavy components from the silane. The gas flow rate is 300 mL to 600 mL per minute, the rectification pressure is 0.1 MPa to 0.4 MPa, and the rectification temperature is -10℃ to 5℃.

[0026] Table 1 Parameters of silane feedstock and protective gas

[0027]

[0028]

[0029] Table 2 Parameters for catalytic synthesis and condensation separation

[0030]

[0031] Table 3 Product Refining Parameters

[0032]

[0033] Comparative Examples

[0034] Comparative Example 1

[0035] Compared with Example 1, the difference in this comparative example is that the purity of the raw material silane in this comparative example is 98%.

[0036] Comparative Example 2

[0037] Compared with Example 2, the difference in this comparative example is that the purity of the raw material silane in this comparative example is 95%.

[0038] Comparative Example 3

[0039] Compared with Example 1, the difference in this comparative example is that the wavelength of the ultraviolet light source for photocatalysis in this comparative example is 300-350nm.

[0040] Comparative Example 4

[0041] Compared with Example 1, the difference in this comparative example is that the wavelength of the light source for photocatalysis in this comparative example is 400-450 nm.

[0042] Conclusion 1: The purity of hexachlorosilane obtained using the process parameters for preparing hexachlorosilane provided in Examples 1-5 reached 6N.

[0043] Conclusion 2: The purity of the product obtained in Comparative Example 1 was 4N7, while the purity of the product obtained in Comparative Example 2 was 4N5. It can be seen that the decrease in the purity of trichlorosilane raw material will lead to a decrease in the purity of the product.

[0044] Conclusion 3: Compared with the product purity of 4N7 obtained in Example 3, the product purity of 4N5 obtained in Example 3 shows that using a light source wavelength outside the scope of the present invention will lead to a decrease in product purity.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A process for the synthesis and purification of electronic grade hexachlorodisilane, characterized in that: Firstly, the trichlorosilane raw material is mixed with the protective gas in a raw material buffer tank, and then the obtained mixed gas is introduced into a photocatalytic reactor to be catalytically synthesized under the action of an ultraviolet light source to obtain a mixed gas containing hexachloroethyldisilane, trichlorosilane and propylsilane; the mixed gas is condensed under the action of a refrigerant, the gaseous trichlorosilane is recycled to the raw material buffer tank to continue to participate in the catalytic synthesis reaction, the mixed liquid of hexachloroethyldisilane and trichlorosilane is introduced into a cold trap, and finally the mixed liquid is warmed and vaporized to be subjected to two-step refining treatment of light component removal and heavy component removal to obtain hexachloroethyldisilane; The purity of the trichlorosilane raw material is greater than 99.9%, and the protective gas is helium or argon; The wavelength range of the ultraviolet light source is 360nm-400nm; The catalytic synthesis is carried out in the photocatalytic reactor, the reaction pressure is 0.5MPa-1.5MPa, and the reaction temperature is 10℃-60℃.

2. A process for synthesis and purification of electronic grade hexachlorodisilane as claimed in claim 1 wherein: The flow rate of the trichlorosilane raw material is 500mL-800mL per minute, and the flow rate of the protective gas is 50mL-80mL per minute.

3. A process for synthesis and purification of electronic grade hexachlorodisilane as claimed in claim 1 wherein: The condensation conditions are that the refrigerant temperature is-20℃--35℃, the pressure is 0.3MPa-0.5MPa, and the gas flow rate is 300mL-600mL per minute.

4. A process for synthesis and purification of electronic grade hexachlorodisilane as claimed in claim 1 wherein: The two-step refining is light component removal and heavy component removal, The light component removal conditions are that the gas flow rate is 300mL-600mL per minute, the refrigerant temperature is-20℃--35℃, the rectification pressure is 0.4MPa-0.8MPa, the rectification temperature is-5℃-20℃, and the light components in the removed mixed gas are removed; The heavy component removal conditions are that the gas flow rate is 300mL-600mL per minute, the refrigerant temperature is-20℃--35℃, the rectification pressure is 0.1MPa-0.4MPa, the rectification temperature is-10℃-5℃, and the heavy components in the removed mixed gas are removed.

5. A process for synthesis and purification of electronic grade hexachlorodisilane as claimed in claim 4 wherein: The refrigerants for the condensation, light component removal and heavy component removal are dichloromethane or ethylene glycol.

6. A process for synthesis and purification of electronic grade hexachlorodisilane as claimed in claim 1 wherein: The purity of the hexachloroethyldisilane reaches the electronic grade.

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