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CN-122010181-A - Synthesis process of tungsten hexafluoride

CN122010181ACN 122010181 ACN122010181 ACN 122010181ACN-122010181-A

Abstract

The invention discloses a synthesis process of tungsten hexafluoride, and relates to the technical field of synthesis of special gases. The process comprises the steps of mixing ammonium fluoride with hydrofluoric acid to obtain an activated solution, carrying out ultrasonic activation treatment on tungsten powder to obtain pretreated tungsten powder, reacting with fluorine gas at a certain temperature and under a certain pressure to obtain liquefied crude tungsten hexafluoride, carrying out sol-gel, ethanol supercritical drying and calcination on aluminum sec-butoxide and the like serving as raw materials to obtain highly porous active alumina, gasifying the crude tungsten hexafluoride, adsorbing and rectifying the gasified active alumina to obtain purified tungsten hexafluoride liquid, finally dissolving the purified tungsten hexafluoride in liquid sulfur dioxide, carrying out treatment under 395nm wavelength illumination, and carrying out distillation separation to obtain the high-purity tungsten hexafluoride. The invention combines activation pretreatment and multistage purification, and remarkably improves the purity and the synthesis efficiency of tungsten hexafluoride.

Inventors

  • CHEN WEIJUN
  • OuYang Zengtu
  • LIU YANJUN
  • LIAO DONG

Assignees

  • 深圳市辰中科技有限公司

Dates

Publication Date
20260512
Application Date
20260205

Claims (8)

  1. 1. The synthesis process of tungsten hexafluoride is characterized by comprising the following steps: step one, carrying out activation pretreatment on tungsten powder, and then carrying out fluorination reaction on the tungsten powder and fluorine gas to obtain liquefied crude tungsten hexafluoride; Step two, preparing highly porous active alumina; Step three, gasifying the liquefied crude tungsten hexafluoride, and sequentially carrying out adsorption and rectification treatment on the highly porous activated alumina to obtain purified tungsten hexafluoride liquid; And step four, dissolving the purified tungsten hexafluoride liquid in liquid sulfur dioxide, treating under specific wavelength illumination, and then obtaining the high-purity tungsten hexafluoride through fractional distillation.
  2. 2. The process for synthesizing tungsten hexafluoride according to claim 1, wherein the particle size of the tungsten powder in the first step is 8-10 μm, and the purity is 99.9%.
  3. 3. The tungsten hexafluoride synthesis process according to claim 1, wherein the specific process of the activation pretreatment is characterized in that ammonium fluoride and hydrofluoric acid are mixed according to a mass ratio of1 (25-29) to obtain an activation solution, tungsten powder is placed in the activation solution at a concentration of 8-12 g/L, ultrasonic treatment is carried out for 20-30 min at a temperature of 25-30 ℃ and a power of 300-500W, and the pretreatment tungsten powder is obtained after filtration, washing for 3-5 times by deionized water and vacuum drying.
  4. 4. The tungsten hexafluoride synthesis process according to claim 1, wherein the fluorination reaction conditions in the first step are that the pretreated tungsten powder is placed in a reaction zone, fluorine gas is introduced at an apparent gas speed of 0.02-0.1 m/s at 200-400 ℃, the system pressure is controlled to be 0.3-0.5 MPa, fluorine introduction is stopped when the fluorine gas concentration in the outlet gas is reduced to 4% -6% of the initial value, and the outlet gas is cooled to-20 to-10 ℃ for condensation, so that liquefied crude tungsten hexafluoride is obtained.
  5. 5. The process for synthesizing tungsten hexafluoride according to claim 1, wherein the method for preparing the highly porous activated alumina in the second step includes: (1) Mixing aluminum sec-butoxide, ethanol and deionized water according to the mass ratio of (2.8-3.2) (0.02-0.06), and stirring at 65-70 ℃ until the mixture is sol-like to prepare alumina sol; (2) Dissolving aluminum chloride hexahydrate with the mass of 0.8-0.9 times of that of aluminum sec-butoxide into absolute ethyl alcohol at the concentration of 70-75wt% to prepare an aluminum chloride solution; (3) Pouring the aluminum chloride solution into the alumina sol under the stirring of 25-30 ℃, aging for 2-3 days at 25-30 ℃ after reacting for 8-10 min, and washing with ethanol every 12h to obtain alumina wet gel; (4) Placing the alumina wet gel in a high-pressure reaction kettle, injecting absolute ethyl alcohol for immersing, maintaining for 2-3 hours at 240-250 ℃ and 60-70 bar for supercritical drying, and reducing to 25-30 ℃ after pressure relief to obtain an alumina aerogel precursor; (5) And calcining the alumina aerogel precursor for 1.5-2.5 hours at 490-510 ℃ to obtain the highly porous activated alumina.
  6. 6. The tungsten hexafluoride synthesis process according to claim 1, wherein the tungsten hexafluoride crude product is gasified by a preheater at 40-50 ℃, then the liquefied tungsten hexafluoride crude product is introduced into an adsorption tower filled with the highly porous active alumina from the bottom, and then the adsorption tower enters a rectifying tower for liquefaction, high-purity helium is introduced into the rectifying tower at 10-20 ℃ to keep the liquid boiling, and the evaporated gas rises in the rectifying column and is condensed and refluxed to obtain the purified tungsten hexafluoride liquid.
  7. 7. The tungsten hexafluoride synthesis process according to claim 1, wherein the specific process of the fourth step is that the purified tungsten hexafluoride liquid is dissolved in liquid sulfur dioxide, light irradiation treatment is carried out for 1-2 hours at-10 to-5 ℃ with 395nm wavelength, liquid is collected through filtration, distillation is carried out at-5~0 ℃, evaporated sulfur dioxide is collected, temperature is raised to 25-30 ℃, and evaporated high-purity tungsten hexafluoride is collected.
  8. 8. The process for synthesizing tungsten hexafluoride according to claim 1, wherein the purity of the high purity tungsten hexafluoride obtained in the fourth step is 99.999%.

Description

Synthesis process of tungsten hexafluoride Technical Field The invention relates to the technical field of synthesis of special gases, in particular to a tungsten hexafluoride synthesis process. Background Tungsten hexafluoride is one of the key process gases essential in the manufacture of semiconductor integrated circuits, and is mainly used in Chemical Vapor Deposition (CVD) and other steps to form a metal tungsten film, and the purity of the tungsten hexafluoride directly relates to the performance and yield of the final chip product. At present, tungsten powder and fluorine gas are commonly adopted for preparation in industry by a direct fluorination process, however, the crude product prepared by the method often contains complexes such as hydrogen fluoride, metal fluoride impurities, tungsten oxyfluoride and the like, the traditional purification has limited effect of removing specific impurities, and the requirement of high-end semiconductor manufacturing on gas purity is difficult to meet. In recent years, with the rapid development of integrated circuit process technology, the line width is continuously shrinking, and the purity requirements of electronic gases such as tungsten hexafluoride reach ppb (parts per billion) or even higher. The existing production process faces serious challenges in efficiency and deep purification capability, and the uniformity and electrical characteristics of film deposition can be directly affected by the excessive impurity content. Therefore, the tungsten hexafluoride preparation technology which can be efficiently synthesized and realize deep purification and process flow integration is developed, and has important significance for guaranteeing the safety of a semiconductor industry chain and improving the binary Cheng Jingzheng force. Disclosure of Invention The invention aims to provide a synthesis process of tungsten hexafluoride, which aims to solve the problems in the prior art. In order to solve the technical problems, the invention provides the following technical scheme: A synthesis process of tungsten hexafluoride comprises the following steps: step one, carrying out activation pretreatment on tungsten powder, and then carrying out fluorination reaction on the tungsten powder and fluorine gas to obtain liquefied crude tungsten hexafluoride; Step two, preparing highly porous active alumina; Step three, gasifying the liquefied crude tungsten hexafluoride, and sequentially carrying out adsorption and rectification treatment on the highly porous activated alumina to obtain purified tungsten hexafluoride liquid; And step four, dissolving the purified tungsten hexafluoride liquid in liquid sulfur dioxide, treating under specific wavelength illumination, and then obtaining the high-purity tungsten hexafluoride through fractional distillation. As optimization, the particle size of the tungsten powder in the first step is 8-10 mu m, the purity is 99.9%, and the manufacturer is Star dust technology (Guangzhou) Co. The specific process of the activation pretreatment in the step one comprises the steps of mixing ammonium fluoride and hydrofluoric acid according to a mass ratio of 1 (25-29) to obtain an activation solution, placing tungsten powder into the activation solution according to a concentration of 8-12 g/L, carrying out ultrasonic treatment at 25-30 ℃ and 300-500W for 20-30 min, filtering, washing 3-5 times by deionized water, and carrying out vacuum drying to obtain the pretreated tungsten powder. The condition of the fluorination reaction in the first step is that the pretreated tungsten powder is placed in a reaction zone, fluorine gas is introduced at the apparent gas speed of 0.02-0.1 m/s at the temperature of 200-400 ℃, the pressure of the system is controlled to be 0.3-0.5 MPa, fluorine introduction is stopped when the concentration of the fluorine gas in the outlet gas is reduced to 4% -6% of the initial value, and the outlet gas is cooled to-20 to-10 ℃ for condensation, so that liquefied crude tungsten hexafluoride is obtained. As an optimization, the preparation method of the highly porous activated alumina in the second step comprises the following steps: (1) Mixing aluminum sec-butoxide, ethanol and deionized water according to the mass ratio of (2.8-3.2) (0.02-0.06), and stirring at 65-70 ℃ until the mixture is sol-like to prepare alumina sol; (2) Dissolving aluminum chloride hexahydrate with the mass of 0.8-0.9 times of that of aluminum sec-butoxide into absolute ethyl alcohol at the concentration of 70-75wt% to prepare an aluminum chloride solution; (3) Pouring the aluminum chloride solution into the alumina sol under the stirring of 25-30 ℃, aging for 2-3 days at 25-30 ℃ after reacting for 8-10 min, and washing with ethanol every 12h to obtain alumina wet gel; (4) Placing the alumina wet gel in a high-pressure reaction kettle, injecting absolute ethyl alcohol for immersing, maintaining for 2-3 hours at 240-250 ℃ and 60-70 bar for supercritic