Purification method of electronic-grade hafnium tetrachloride

Abstract

The invention discloses a method for purifying electronic-grade hafnium tetrachloride, which comprises the following steps of: removing insoluble substances by adopting an organic solvent matched with hafnium tetrachloride, removing low-melting-point impurities through low-temperature boiling, removing high-melting-point impurities through high-temperature sublimation, and removing substances with different chemical properties and polarities through a complexing and decomplexing method. And finally, sublimating to further remove impurities to finally obtain the electronic-grade hafnium tetrachloride with the purity not lower than 7N grade. The method has the characteristics of good purification effect, multi-method comprehensive impurity removal, industrial large-scale application, stable quality, high yield and simple and easy-to-separate impurity components.

Description

Technical Field

[0001] The present invention relates to a high-purity semiconductor dopant, and particularly to a purification method for electronic-grade hafnium tetrachloride. Background Art

[0002] Doping of semiconductors is to improve the electrical properties of semiconductor devices, and many electrical characteristics of semiconductors are related to the impurity concentration of doping.

[0003] In the prior art, hafnium tetrachloride is mainly prepared by the method of hafnium powder chlorination, which refers to a method of generating hafnium tetrachloride through processes such as pulverization, drying, chlorination reaction, and condenser condensation using hafnium oxide, carbon tetrachloride, chlorine, etc. as raw materials. Zirconium and hafnium are associated, and the purity of hafnium tetrachloride generated by the method of hafnium powder chlorination is relatively low, generally containing a certain amount of a series of chloride impurities such as zirconium tetrachloride, ferric chloride, and titanium tetrachloride.

[0004] Hafnium tetrachloride has a wide range of application fields. Among them, the purity above 5N level (impurity content not higher than 0.001%) can be used as a precursor in fields such as semiconductors, ultra-high temperature ceramics, high-power LEDs, and atomic reactors. In recent years, driven by the rapid development of the downstream market, the market demand for hafnium tetrachloride has been increasing continuously, and the demand space is relatively broad. However, there are obvious shortcomings in the production and technology of high-purity hafnium tetrachloride (electronic-grade hafnium tetrachloride) in China.

[0005] In the current prior art, there is no related technology to solve the above problems. At present, a purification method for electronic-grade hafnium tetrachloride with good purification effect, comprehensive impurity removal by multiple methods, applicable to industrial scale, stable quality, and high yield is needed. Summary of the Invention

[0006] The present invention aims to provide a purification method for electronic-grade hafnium tetrachloride with good purification effect, comprehensive impurity removal by multiple methods, applicable to industrial scale, stable quality, high yield, and simple and easy separation of impurity components.

[0007] To achieve the above object, the present invention adopts the following technical solutions: A purification method for electronic-grade hafnium tetrachloride, the purification method includes the following stages: S1: Raw material preparation ① Raw material preparation: Prepare sufficient amounts of hafnium tetrachloride solid with a mass purity not lower than 99.9%, 1-bromo-2,3,4,6-tetraacetoxy-D-glucose, trimethylsilyl azide, tetrabutylammonium fluoride, tetrahydrofuran, ethanol, and argon; ② Tooling and equipment preparation: Prepare a water bath constant temperature device, a quartz sublimation tower, a vacuum chamber with a vacuum degree of 1×10 -4 Pa to 50 Pa, a quartz encapsulation container, a rotary evaporator, and a chromatography column; S2: Pretreatment ① After completely dissolving the hafnium tetrachloride solid prepared in step ① of stage S1 with the ethanol prepared in step ① of stage S1, filter out the solid content, and then dry the solution to obtain clean hafnium tetrachloride; ② First, heat the clean hafnium tetrachloride prepared in step ① of stage S1 to 270 °C - 340 °C. After the low-boiling impurities volatilize until the mass is stable, obtain the preliminarily purified hafnium tetrachloride; ③ Place the preliminarily purified hafnium tetrachloride obtained in step ① into the vacuum chamber prepared in step ② of stage S1. Control the vacuum degree at 10 Pa - 50 Pa, heat to 220 °C - 250 °C, and use a quartz container with a temperature range of 130 °C - 100 °C to receive it under the same vacuum degree. After receiving, place the quartz container in an inert anhydrous environment to scrape the material to obtain 5N grade hafnium tetrachloride; S3: Purification by complexation and decomplexation ① Mix 1-bromo-2,3,4,6-tetraacetoxy-D-glucose, trimethylsilyl azide, and tetrabutylammonium fluoride prepared in step ① of stage S1 in a strict ratio of 10:10.6:25.35 by mass under argon protection, and then add 1.2 - 1.3 times the total mass of the mixture of tetrahydrofuran prepared in step ① of stage S1 under argon protection. Maintain a stirring rate of 15 rpm - 30 rpm at room temperature and stir continuously for 26 h - 32 h to obtain a mixed reaction solution; ② Under argon protection, use the rotary evaporator prepared in step ② of stage S1 to evaporate the solvent of the mixed reaction solution obtained in step ①, and then separate by column chromatography (EA:PE = 1:15) to obtain a white solid, which is the complexing agent; ③ Weigh 1 portion of the complexing agent obtained in step ② using an analytical balance, add ethanol 3 - 4 times the mass of the complexing agent, and perform ultrasonic treatment with 250 W - 320 W to completely dissolve the complexing agent to obtain a complexing mother liquor. Then dilute the mother liquor with ethanol to a concentration of 15×10 -5 mol / L - 18×10 -5 mol / L as the complexing solution for purification; ④ Place the 5N grade hafnium tetrachloride obtained in step ② of stage S2 into the complexing solution obtained in step ③, stir to form a suspension, and let the reaction system stand and settle to allow the complex to fully settle and crystallize. Filter out the solidified product after complexation; wash the solidified product with a non-polar organic solvent to remove the uncomplexed substances attached to the surface of the solidified product. Finally, heat the complex to decompose and separate it; after distilling and purifying the separated substance, obtain the complexation and decomplexation purified hafnium tetrachloride; S4: Vacuum sublimation ①In the usage stage S1, the quartz sublimation tower prepared in step ② is used to perform reduced-pressure sublimation on the complexed and decomplexed purified hafnium tetrachloride obtained in step ③ of S3. The sublimation parameters are the same as those in step ③ of stage S2. Before sublimation, the sublimation system is purged with vacuum and argon gas. After purging, ensure that the system is in a slightly positive pressure state to prevent ambient air from entering the system and affecting sublimation. After sublimation, sublimated hafnium tetrachloride is obtained; S5: Detection ①The sublimated hafnium tetrachloride obtained in step ① of stage S4 is detected. The requirements are that the impurity content is not higher than 0.000001%, the moisture content is not greater than 2 ppm, and the content of sublimated hafnium tetrachloride is not lower than 99.9%, so as to obtain the target sublimated hafnium tetrachloride; S6: Encapsulation ①The sublimated hafnium tetrachloride that passes the detection in step ① of stage S5 is encapsulated in the vacuum chamber prepared in step ② of stage S1 using the quartz encapsulation container prepared in step ② of stage S1. After encapsulation and sealing, the required electronic-grade hafnium tetrachloride is obtained.

[0008] Compared with the prior art, due to the adoption of the above technical solutions, the present invention has the following advantages: (1) The main function of the present invention is to accurately identify and complex hafnium metal ions using the principle of molecular structure. This method uses the molecular characteristics of hafnium tetrachloride for purification, and is particularly suitable for purification after rough distillation. The purification method adopted by the present invention not only has simple process conditions, low energy consumption, simple equipment, low equipment maintenance frequency, short cycle period, and no special requirements for raw materials, but also has good comprehensive purification effect. The complexation separation technology used in the present invention is different from general purification technologies and can be used in complementary applications with existing commonly used technologies.

[0009] (2) In the present invention, physical pre-purification is first carried out. After removing insoluble substances using an organic solvent compatible with hafnium tetrachloride, low-melting-point impurities are removed by low-temperature distillation, and high-melting-point substances are removed by high-temperature sublimation and temperature condensation under vacuum conditions. A purity of 5N (purity not lower than 99.999%) can be obtained only through the pretreatment, and this condition already meets the requirements of the 14nm manufacturing process.

[0010] Therefore, the present invention has the characteristics of good purification effect, comprehensive impurity removal by multiple methods, applicable to industrial-scale applications, stable quality, high yield, and simple impurity components easy to separate. Specific Embodiments Example 1

[0011] A purification method for electronic-grade hafnium tetrachloride, which includes the following stages: S1: Raw material preparation ① Raw material preparation: Prepare sufficient hafnium tetrachloride solid with a mass purity of not less than 99.9%, 1-bromo-2,3,4,6-tetraacetoxy-D-glucose, trimethylsilyl azide, tetrabutylammonium fluoride, tetrahydrofuran, ethanol, and argon; ② Tooling and equipment preparation: Prepare a water bath constant temperature device, a quartz sublimation tower, a vacuum chamber with a vacuum degree of 1×10 -4 Pa to 50 Pa, a quartz encapsulation container, a rotary evaporator, and a chromatography column; S2: Pretreatment ① Completely dissolve the hafnium tetrachloride solid prepared in step ① of stage S1 with the ethanol prepared in step ① of stage S1, then filter out the solid content, and then dry the solution to obtain clean hafnium tetrachloride; ② First heat the clean hafnium tetrachloride prepared in step ① of stage S1 to 270°C to 340°C. After the low-boiling impurities volatilize to a stable mass, obtain preliminarily purified hafnium tetrachloride; ③ Place the preliminarily purified hafnium tetrachloride obtained in step ① into the vacuum chamber prepared in step ② of stage S1, control the vacuum degree to 10 Pa to 50 Pa, heat it to 220°C to 250°C, use a quartz container with a temperature range of 130°C to 100°C to receive it under the same vacuum degree. After receiving, place the quartz container in an inert anhydrous environment to scrape the material to obtain 5N grade hafnium tetrachloride; S3: Purification by complexation and decomplexation method ① Mix 1-bromo-2,3,4,6-tetraacetoxy-D-glucose, trimethylsilyl azide, and tetrabutylammonium fluoride prepared in step ① of stage S1 in a strict ratio of 10:10.6:25.35 by mass, mix them evenly under argon protection, and then add 1.2 to 1.3 times the total mass of the mixture of tetrahydrofuran prepared in step ① of stage S1 under argon protection. Maintain a stirring rate of 15 rpm to 30 rpm at room temperature and continuously stir for 26 h to 32 h to obtain a mixed reaction solution; ② Under argon protection, use the rotary evaporator prepared in step ② of stage S1 to evaporate the solvent of the mixed reaction solution obtained in step ①, and then separate to obtain a white solid through column chromatography (EA:PE = 1:15). The white solid is a complexing agent; ③ Weigh 1 portion of the complexing agent obtained in step ② using an analytical balance, add ethanol 3 to 4 times the mass of the complexing agent, and perform ultrasonic treatment with 250 W to 320 W to completely dissolve the complexing agent to obtain a complexing mother liquor. Then dilute the mother liquor with ethanol to a concentration of 15×10 -5 mol / L to 18×10 -5 mol / L as the complexing solution for purification; ④ Place the 5N hafnium tetrachloride obtained in step ② of stage S2 into the complexing solution obtained in step ③, stir to form a suspension, let the reaction system stand and settle to allow the complex to fully settle and crystallize, and filter out the solidified product after complexation; wash the solidified product with a non-polar organic solvent to remove the uncomplexed substances attached to the surface of the solidified product, and finally heat the complex to decompose and separate it; after distilling and purifying the separated substance, obtain complexation-removal and purification hafnium tetrachloride; S4: Vacuum sublimation ① Use the quartz sublimation tower prepared in step ② of stage S1 to perform vacuum sublimation on the complexation-removal and purification hafnium tetrachloride obtained in step ③ of S3. The sublimation parameters are the same as those in step ③ of stage S2. Before sublimation, use vacuum and argon to perform gas replacement on the sublimation system. After replacement, ensure that the system is in a slightly positive pressure state to ensure that ambient air will not enter the system and affect sublimation. After sublimation, obtain sublimated hafnium tetrachloride; S5: Detection ① Detect the sublimated hafnium tetrachloride obtained in step ① of stage S4. It is required that the impurity content is not higher than 0.000001%, the moisture content is not greater than 2 ppm, and the content of sublimated hafnium tetrachloride is not lower than 99.9% to obtain the target sublimated hafnium tetrachloride; S6: Encapsulation ① Encapsulate the sublimated hafnium tetrachloride qualified in step ① of stage S5 in the vacuum chamber prepared in step ② of stage S1 using the quartz encapsulation container prepared in step ② of stage S1. After encapsulation and sealing, obtain the required electronic-grade hafnium tetrachloride.

[0012] The electronic-grade hafnium tetrachloride obtained according to this embodiment has the characteristics of good purification effect, comprehensive impurity removal by multiple methods, applicable to industrial-scale applications, stable quality, high yield, and simple impurity components and easy separation.

[0013] The above description of the disclosed embodiments is only to enable those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for purifying electronic grade hafnium tetrachloride, characterized in that: The purification method The following phases are included: S1: Raw material preparation ① Raw material preparation: prepare sufficient amount of solid hafnium tetrachloride with a purity of not less than 99.9%, 1-bromo-2,3,4,6-tetraacetoxy-D-glucose, trimethylsilyl azide, tetrabutylammonium fluoride, tetrahydrofuran, ethanol, and argon; ② Preparation of tools and equipment: prepare water bath thermostat, quartz sublimation tower, vacuum degree 1×10 -4 Pa~50Pa vacuum chamber, quartz packaging container, rotary evaporator, chromatography column; S2: Preprocessing ① using the ethanol prepared in step ① of stage S1 to completely dissolve the hafnium tetrachloride solid prepared in step ① of stage S1, then filtering out the solid content, and then drying the solution to obtain clean hafnium tetrachloride; ② The clean hafnium tetrachloride prepared in step ① of stage S1 is first heated to 270°C to 340°C, and after the low-boiling impurities are volatilized to a stable quality, the initially purified hafnium tetrachloride is obtained; ③ Place the initially purified hafnium tetrachloride obtained in step ① in the vacuum chamber prepared in step ② of stage S1, control the vacuum degree to 10Pa-50Pa, raise the temperature to 220°C-250°C, and use a quartz container with a temperature range of 130°C-100°C to receive it under the same vacuum degree. After receiving, place the quartz container in an inert anhydrous environment to scrape the material to obtain 5N grade hafnium tetrachloride; S3: Purification by complexation and decomplexation ① The 1-bromo-2,3,4,6-tetraacetoxy-D-glucose, trimethylsilyl azide and tetrabutylammonium fluoride prepared in step ① of stage S1 are mixed in a strict mass ratio of 10:10.6:25.35 under the protection of argon, and then 1.2 to 1.3 times the total mass of tetrahydrofuran prepared in step ① of stage S1 is added to the mixture under the protection of argon, and the stirring rate is maintained at 15 rpm to 30 rpm for 26 h to 32 h at room temperature to obtain a mixed reaction liquid; ② Under argon protection, the mixed reaction solution solvent obtained in step ① is evaporated using the rotary evaporator prepared in step ② of stage S1, and then separated by column chromatography (EA:PE=1:15) to obtain a white solid, which is a complexing agent; ③ Use an analytical balance to weigh 1 part of the complexing agent obtained in step ②, add 3 to 4 times the mass of ethanol to the complexing agent, and use 250W to 320W ultrasonic treatment to completely dissolve the complexing agent to obtain the complexing mother liquor, and then use ethanol to dilute the mother liquor to 15×10 -5 mol / L~18×10 -5 mol / L concentration as the complexing solution for purification; ④ Place the 5N grade hafnium tetrachloride obtained in step ② of stage S2 into the complex solution obtained in step ③, stir to form a suspension, let the reaction system stand and settle, allow the complex to fully settle and crystallize, and filter out the solidified product after complexation; wash the solidified product with a non-polar organic solvent to remove the uncomplexed substances attached to the surface of the solidified product, and finally heat the complex to decompose and separate; After the separated material is distilled and purified, the complexed and decomplexed purified hafnium tetrachloride is obtained; S4: Decompression sublimation ① Using the quartz sublimation tower prepared in step ② of stage S1, the decomplexed and purified hafnium tetrachloride obtained in step ③ of S3 is subjected to reduced pressure sublimation. The sublimation parameters are consistent with those in step ③ of stage S2. Before sublimation, the sublimation system is gas-replaced with vacuum and argon. After the gas replacement, the system is kept in a slightly positive pressure state to ensure that ambient air does not enter the system and affect the sublimation. After sublimation, sublimated hafnium tetrachloride is obtained; S5: Detection ① Testing the sublimated hafnium tetrachloride obtained in step ① of stage S4, requiring the impurity content to be no higher than 0.000001%, the water content to be no greater than 2 ppm, and the sublimated hafnium tetrachloride content to be no less than 99.9%, to obtain the target sublimated hafnium tetrachloride; S6: Encapsulation ① The sublimed hafnium tetrachloride that has passed the test in step ① of stage S5 is packaged in the vacuum chamber prepared in step ② of stage S1 using the quartz packaging container prepared in step ② of stage S1. After the packaging is completed and sealed, the required electronic grade hafnium tetrachloride is obtained.