A method for purifying electronic grade hafnium tetrachloride

Abstract

A purification method for electronic-grade hafnium tetrachloride, comprising the following steps: S1: After loading crude hafnium tetrachloride into a quartz boat under the protection of an inert gas, place the quartz boat into the purification system; S2: Turn on the vacuum pump and pump the vacuum degree of the purification system to 10⁻³~10⁻¹ Pa; S3: Raise the temperature of the tubular heating reaction furnace to 100~220 °C at a heating rate of 10 °C / min; S4: Keep the tubular heating reaction furnace at a constant temperature for 8 - 15 hours; and keep the vacuum degree of the purification system at 10⁻³~10⁻¹ Pa for sublimation purification; S5: Lower the temperature of the purification system to room temperature, connect the purification system to a glove box, under the protection of an inert gas, remove the condensation collector, collect the powder and seal it in a pressure vessel to obtain electronic-grade hafnium tetrachloride. Using this method, the purity of the hafnium tetrachloride product reaches 5N and 6N.

Description

Technical Field

[0001] The invention relates to the field of halide purification technology, and in particular to a method for purifying hafnium tetrachloride. Background Art

[0002] Hafnium tetrachloride is a colorless white powder, mainly used in the pharmaceutical industry, fine organic synthesis and electronic semiconductor industry. Hafnium tetrachloride is an extremely important electronic grade rare metal chloride in the semiconductor industry. The purity of electronic grade rare metal chloride required by the electronics industry is usually not less than 5N, mainly limiting the content of various alkaline metals (Na, K, Ca, Al) and transition metals (Fe, Cu, Zn) elements and non-metallic elements such as P and S. These impurity elements will seriously affect the preparation of semiconductors and cause serious defective rates. In the production process of hafnium tetrachloride, impurities such as FeCl3, AlCl3, TiCl4, SiCl4, etc. are often present. The boiling point of FeCl3 is close to that of hafnium tetrachloride and it is difficult to remove. These impurities have a great impact on the product quality of hafnium tetrachloride, and purification methods must be used to remove these impurities. Traditional purification methods include hydrogenation sublimation, vacuum decompression sublimation, wet scrubbing filtration, molten salt purification, etc. These methods have disadvantages such as unstable operation, single impurity removal, and low efficiency. Among them, the sublimation impurity removal method entrains some high-boiling solid particles when a large amount of gas molecules escape during the impurity removal process, and it is impossible to effectively separate the gas molecules from the solid particles. This technology has the technical difficulty of separating high-boiling impurities. Summary of the invention

[0003] The invention provides a high-yield and safe purification method for electronic-grade hafnium tetrachloride, which is used to solve the current technical problem of difficulty in purifying electronic-grade hafnium tetrachloride.

[0004] To achieve the purpose of the present invention, the following technical scheme is adopted: a method for purifying electronic grade hafnium tetrachloride, comprising the following steps:

[0005] S1: Under the protection of inert gas, the crude hafnium tetrachloride is loaded into a quartz boat and then placed in a purification system of the quartz boat, wherein the purification system comprises a tubular heating reaction furnace, the rear end of which is connected to the air inlet of a filter, the filter is filled with filter material, the air outlet of the filter is connected to a condenser receiver, the condenser receiver is connected to a vacuum pump, the quartz boat is placed in the tubular heating reaction furnace, and the purification system is sealed;

[0006] S2: Turn on the vacuum pump and pump the vacuum degree of the purification system to 10 -3 ~10 -1 Pa;

[0007] S3: raising the temperature of the tubular heating reactor to 100-220°C at a heating rate of 10°C / min;

[0008] S4: Keep the tubular heating reactor warm for 8-15 hours; and keep the vacuum degree of the purification system at 10 -3 ~10 -1 Pa, for sublimation purification;

[0009] S5: Lower the temperature of the purification system to room temperature, connect the purification system to the glove box, protect with inert gas, remove the condenser receiver, collect the powder and seal it in a pressure vessel to obtain electronic grade hafnium tetrachloride.

[0010] Furthermore, the purity of the crude hafnium tetrachloride is greater than 99.99%, and its particle size is 20~60 mesh.

[0011] Furthermore, the filter material is a molecular sieve or activated carbon or a high-purity filter membrane, and the pore size of the filter material is less than 10 microns.

[0012] Furthermore, the molecular sieve filter material is made of alkali metal aluminum silicate with a pore size of 10Å; the activated carbon filter material has a pore size of 10 nm~20 nm; and the high-purity filter membrane has a pore size of 0.1 µm.

[0013] Furthermore, the filter material is pretreated before use, and the pretreatment steps are: baking, chlorine purification, and argon replacement.

[0014] Furthermore, the temperature of the filter is consistent with that of the tubular heating reaction furnace.

[0015] Furthermore, the vacuum pump is a molecular pump.

[0016] The positive and beneficial technical effect of the present invention is that in the synthesis stage, hafnium oxide and other metal oxides are basically chlorinated into metal chlorides, high-boiling substances such as CaCl2, ZnCl2, KCl, MgCl2, NaCl, etc., and low-boiling impurities such as AlCl3, NbCl5, SiCl4, etc., so the collected hafnium tetrachloride contains a large amount of chloride impurities, and the amount of impurities depends on the purity of hafnium oxide. The present invention provides a hafnium tetrachloride filtration and impurity removal technology, which utilizes the difference between the vapor pressure of the solid mixture and the volatile matter, and achieves the solid impurity separation effect by adjusting the vacuum degree to change the vapor pressure difference; according to the different vapor pressures or volatility of the solid mixture, the impure solid compound is heated to the sublimation temperature, and the product is directly gasified without going through the liquid process by utilizing the vapor pressure difference, and solidifies after being cooled, while the impurities do not undergo or rarely undergo this process, thereby achieving the purpose of separating the solid mixture, and changing the vacuum condition can increase or decrease the vapor pressure difference between the product and the impurities, thereby achieving the purpose of deep purification. For the separation of high-boiling impurities in hafnium tetrachloride, a separation technology based on the size difference between gas molecules and solid particles is proposed for the first time. That is, gas molecules are several nanometers in size, while solid impurities are generally at the micron level. According to the size difference, high-boiling impurities can be deeply separated. The filter material with nanometer pore size is selected so that the high-boiling solid particles are adsorbed and intercepted, and the purpose of separating high-boiling impurities is achieved efficiently. The invention is easy to operate, green and safe, and can efficiently separate a variety of high-boiling impurities. The purity of the final hafnium tetrachloride product reaches 5N and 6N. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the purification system of the present invention.

[0018] Figure 2 is a schematic diagram of the filter. DETAILED DESCRIPTION

[0019] In order to more fully explain the implementation of the present invention, embodiments of the present invention are provided. These embodiments are merely elaborations of the present invention and do not limit the scope of the present invention.

[0020] The present invention is further explained in detail in conjunction with the accompanying drawings, in which the marks are: 1: inlet flange; 2: tubular heating reactor; 3: reaction tube of tubular reactor; 4: filter; 5: condensation receiver; 6: vacuum pump; 7: bellows; 41: air inlet; 42: high-purity filter membrane; 43: film pressing rack; 44: lid opening handle; 45: sealing gasket flange; 46: air outlet; 47: activated carbon / molecular sieve filling net; 48: sewage outlet; 49: heating resistance wire.

[0021] Figure 2 The filter shown in the figure can adapt to three kinds of filter materials. When using it, you can choose to use one kind of filter material.

[0022] In the present invention, the glove box adopts a Vigor single-sided double-station glove box, which is made of 304 stainless steel. The internal dimensions of the box are 1200 mm * 750 mm * 900 mm, and the window adopts 8 mm tempered glass.

[0023] The size of the quartz boat is Ф280 mm * 600 mm *5 mm, and the size of the heating reaction furnace tube is Ф300 mm * 3000mm *5 mm.

[0024] Figure 1 It is a schematic diagram of a purification system. A tubular heating reaction furnace, a filter, and a condensation receiver are detachably connected together by flanges. The condensation receiver comprises an outer cylinder for cooling and an inner sleeve sleeved in the outer cylinder. The cooled material is collected in the inner sleeve. The inner sleeve is butt-jointed by multiple sections. The material can be unloaded section by section when collecting the material. The loading and collecting of the present invention are both carried out by butt-jointing on a glove box under the protection of an inert gas (argon gas may be used).

[0025] Embodiment 1:

[0026] 2 kg of crude hafnium tetrachloride with a purity of 99.995% was placed in a glove box. In the glove box protected by argon, the crude hafnium tetrachloride powder was placed in a quartz boat.

[0027] Push the quartz boat to the tubular heating reactor, connect it to the filter of the tubular heating reactor, the filter material of the filter is molecular sieve, add the pre-treated molecular sieve to the filling net, seal the tubular reactor and the filter, connect the condensation receiver behind the filter, connect the molecular pump (vacuum pump) to the condensation receiver, turn on the vacuum pump, and keep it at about 10 -3 ~10 -1 The vacuum degree of Pa; the molecular sieve pretreatment process is high-temperature drying at 400°C for 4 hours in an argon atmosphere, purification at 800°C for 6 hours in a chlorine atmosphere, and finally argon replacement for 24 hours.

[0028] Run the heating program, raise the temperature to 170℃ at a heating rate of 10℃ / min, keep it warm for about 12 hours, and keep the vacuum degree at about 5*10 -2 Pa, according to the different vapor pressures of the solid mixture, to separate the impurities with different boiling points, sublimation purification is performed, after the system is cooled to room temperature, the powder is collected in an argon environment and sealed in a pressure vessel to obtain electronic grade purity hafnium tetrachloride powder. Table 2 shows the analytical value results of the ICP-MS spectrum of the high purity hafnium tetrachloride obtained in Example 1.

[0029] Example 2.

[0030] 2 kg of crude hafnium tetrachloride was placed in a glove box, and the purity of the crude hafnium tetrachloride was 99.995%. In an argon-protected glove box, the crude hafnium tetrachloride powder was placed in a quartz boat.

[0031] Push the quartz boat to the tubular heating reactor, connect it to the filter of the tubular heating reactor, the filter material of the filter is molecular sieve, add the pre-treated molecular sieve to the filling net, seal the tubular reactor and the filter, connect the condensation receiver behind the filter, connect the molecular pump (vacuum pump) to the condensation receiver, turn on the vacuum pump, and keep it at about 10 -3 ~10 -1 The vacuum degree of Pa; the molecular sieve pretreatment process is high-temperature drying at 400°C for 4 hours in an argon atmosphere, purification at 800°C for 6 hours in a chlorine atmosphere, and finally argon replacement for 24 hours.

[0032] Run the heating program, raise the temperature to 220℃ at a heating rate of 10℃ / min, keep it warm for about 10 hours, and keep the vacuum degree at about 5*10 -1 Pa, according to the different vapor pressures of the solid mixture, to separate the impurities with different boiling points, and to perform sublimation purification. After the system is cooled to room temperature, the powder is collected in an argon environment and sealed in a pressure vessel to obtain hafnium tetrachloride powder of electronic grade purity. Table 2 shows the analytical value results of the ICP-MS spectrum of the high-purity hafnium tetrachloride obtained in Example 2.

[0033] Example 3

[0034] 2 kg of crude hafnium tetrachloride was placed in a glove box, and the purity of the crude hafnium tetrachloride was 99.995%. In an argon-protected glove box, the crude hafnium tetrachloride powder was placed in a quartz boat.

[0035] Push the quartz boat to the tubular heating reactor, connect it to the filter of the tubular heating reactor, the filter material of the filter is activated carbon, add the pre-treated activated carbon into the filling net, seal the tubular reactor and the filter, connect the condensation receiver behind the filter, connect the molecular pump (vacuum pump) to the condensation receiver, turn on the vacuum pump, and keep it at about 10 -3 ~10 -1 Vacuum degree in Pa;

[0036] The activated carbon pretreatment process is high-temperature drying at 400°C for 4 hours in an argon atmosphere, purification at 800°C for 6 hours in a chlorine atmosphere, and finally argon replacement for 24 hours.

[0037] Run the heating program, raise the temperature to 170℃ at a heating rate of 10℃ / min, keep it warm for about 12 hours, and keep the vacuum degree at about 5*10 -2 Pa or lower, while constantly drawing a vacuum, according to the different vapor pressures of the solid mixture, to separate the impurities with different boiling points and perform sublimation purification.

[0038] After the system was cooled to room temperature, the powder was collected in an argon environment and sealed in a pressure vessel to obtain electronic grade hafnium tetrachloride powder. Table 2 shows the analytical value results of the ICP-MS spectrum of the high purity hafnium tetrachloride obtained in Example 3.

[0039] Example 4

[0040] 2 kg of crude hafnium tetrachloride was placed in a glove box, and the purity of the crude hafnium tetrachloride was 99.995%. In an argon-protected glove box, the crude hafnium tetrachloride powder was placed in a quartz boat.

[0041] Push the quartz boat to the tubular heating reactor, connect it to the filter of the tubular heating reactor, the filter material of the filter is activated carbon, add the pre-treated activated carbon into the filling net, seal the tubular reactor and the filter, connect the condensation receiver behind the filter, connect the molecular pump (vacuum pump) to the condensation receiver, turn on the vacuum pump, and keep it at about 10 -3 ~10 -1 Vacuum degree in Pa;

[0042] The activated carbon pretreatment process is high-temperature drying at 400°C for 4 hours in an argon atmosphere, purification at 800°C for 6 hours in a chlorine atmosphere, and finally argon replacement for 24 hours.

[0043] Run the heating program, raise the temperature to 220℃ at a heating rate of 10℃ / min, keep it warm for about 10 hours, and keep the vacuum degree at about 5*10 -1 Pa or lower, according to the different vapor pressures of solid mixtures, in order to separate the impurities with different boiling points, sublimation purification is carried out.

[0044] After the system is cooled to room temperature, the powder is collected in an argon environment and sealed in a pressure vessel to obtain high-purity hafnium tetrachloride powder. Table 2 shows the analytical value results of the ICP-MS spectrum of the high-purity hafnium tetrachloride obtained in Example 4.

[0045] Example 5

[0046] 2 kg of crude hafnium tetrachloride was placed in a glove box, and the purity of the crude hafnium tetrachloride was 99.995%. In an argon-protected glove box, the crude hafnium tetrachloride powder was placed in a quartz boat.

[0047] Push the quartz boat to the tubular heating reactor, connect the tubular heating reactor filter, replace the filter material with a high-purity filter membrane (specifically a high-purity glass fiber filter membrane, produced by Weifang Jukai Electronic Technology Co., Ltd.), put the pre-treated high-purity filter membrane on the filling grid, fix the filter membrane with a film pressing frame, seal the tubular heating reactor and the filter, connect the filter to the condensation receiver, turn on the vacuum pump, and continuously evacuate the vacuum to maintain about 10 -3 ~10-1 Vacuum degree in Pa,

[0048] The membrane pretreatment process was high-temperature drying at 400°C for 4 hours in an argon atmosphere, purification at 600°C for 6 hours in a chlorine atmosphere, and finally argon replacement for 24 hours.

[0049] Run the heating program, raise the temperature to 170℃ at a heating rate of 10℃ / min, keep it warm for about 12 hours, and keep the vacuum degree at about 5*10 -2 Pa or lower, while constantly evacuating the air to separate the metal impurities with different boiling points according to the different vapor pressures of the solid mixture, and perform sublimation purification.

[0050] The system was cooled to room temperature, and the powder was collected in an argon environment and sealed in a pressure vessel to obtain electronic grade hafnium tetrachloride powder. Table 2 shows the analytical value results of the ICP-MS spectrum of the high purity hafnium tetrachloride obtained in Example 5.

[0051] Example 6

[0052] 2 kg of crude hafnium tetrachloride was placed in a glove box, and the purity of the crude hafnium tetrachloride was 99.995%. In an argon-protected glove box, the crude hafnium tetrachloride powder was placed in a quartz boat.

[0053] Push the quartz boat to the tubular heating reactor, connect the tubular heating reactor filter, replace the filter material with a high-purity filter membrane (specifically a high-purity glass fiber filter membrane, produced by Weifang Jukai Electronic Technology Co., Ltd.), put the pre-treated high-purity filter membrane on the filling grid, fix the filter membrane with a film pressing frame, seal the tubular heating reactor and the filter, connect the filter to the condensation receiver, turn on the vacuum pump, and continuously evacuate the vacuum to maintain about 10 -3 ~10 -1 Vacuum degree in Pa,

[0054] The membrane pretreatment process was high-temperature drying at 400°C for 4 hours in an argon atmosphere, purification at 600°C for 6 hours in a chlorine atmosphere, and finally argon replacement for 24 hours.

[0055] Run the heating program, raise the temperature to 120℃ at a heating rate of 10℃ / min, keep it warm for about 14 hours, and keep the vacuum degree at about 2*10 -3 Pa or lower, while constantly drawing a vacuum, according to the different vapor pressures of the solid mixture, to separate the impurities with different boiling points and perform sublimation purification.

[0056] The system was cooled to room temperature, and the powder was collected in an argon environment and sealed in a pressure vessel to obtain high-purity hafnium tetrachloride powder. Table 2 shows the analytical value results of the ICP-MS spectrum of the high-purity hafnium tetrachloride obtained in Example 6.

[0057] The conditions of Examples 1 to 6 are shown in Table 1. The analysis values ​​of the high-purity hafnium tetrachloride obtained in Examples 1 to 6 by ICP-MS spectrum are shown in Table 2.

[0058]

[0059]

[0060] After describing the implementation mode of the present invention in detail, people familiar with the technology can clearly understand that various changes and modifications can be made without departing from the scope and spirit of the above-mentioned patent application. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are within the scope of the present invention, and the present invention is not limited to the implementation mode of the examples given in the specification.

Claims

1. A method for purifying electronic grade hafnium tetrachloride, characterized in that The following steps are involved: S1: under the protection of inert gas, the crude hafnium tetrachloride is loaded into a quartz boat, and then the quartz boat is loaded into a purification system, wherein the purification system comprises a tubular heating reaction furnace, the rear end of which is connected to the air inlet of the filter, the filter is filled with filter material, the air outlet of the filter is connected to a condenser receiver, the condenser receiver is connected to a vacuum pump, the quartz boat is placed in the tubular heating reaction furnace, and the purification system is sealed; S2: Turn on the vacuum pump and pump the vacuum degree of the purification system to 10 -3 ~10 -1 Pa; S3: Raise the temperature of the tubular heating reactor to 100-220°C at a heating rate of 10°C / min; the temperature of the filter is consistent with that of the tubular heating reactor; S4: Keep the tubular heating reactor warm for 8-15 hours; and keep the vacuum degree of the purification system at 10 -3 ~10 -1 Pa, for sublimation purification; S5: lowering the temperature of the purification system to room temperature, placing the purification system in a glove box, protecting it with inert gas, removing the condensation receiver, collecting the powder and sealing it in a pressure vessel, and obtaining electronic grade hafnium tetrachloride; The purity of the crude hafnium tetrachloride is greater than 99.99%, and its particle size is 20-60 meshes; the filter material is activated carbon, and the pore size of the activated carbon filter material is 10 nm-20 nm; the filter material is pretreated before use, and the pretreatment steps are: baking, chlorine purification, and argon replacement. The purity of the purified hafnium tetrachloride is greater than 6N.

2. A method for purifying electronic grade hafnium tetrachloride according to claim 1, characterized in that: The vacuum pump is a molecular pump.

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