Synthetic method of ruthenium hexafluoride

Abstract

The invention belongs to the technical field of preparation of semiconductor high-purity materials, and particularly relates to a synthesis method of ruthenium hexafluoride. Comprising the following steps: S1, adding metal ruthenium into a reactor, purging the reactor with inert gas while heating, then vacuumizing, and repeating purging and vacuumizing; and S2, continuously heating to 450-700 DEG C, then introducing any one of mixed gas of fluorine gas and nitrogen gas and nitrogen trifluoride into the reactor, reacting with the metal ruthenium to generate crude ruthenium hexafluoride, and finally collecting refined ruthenium hexafluoride at low temperature. The ruthenium hexafluoride preparation method is simple, has the characteristics of controllable actual operation, few byproducts, controllable product quality and high product yield, and is suitable for industrial production.

Description

Technical Field

[0001] This application belongs to the technical field of semiconductor high-purity material preparation, and specifically relates to a method for synthesizing ruthenium hexafluoride. Background Art

[0002] As a strong oxidizing agent and fluorinating agent, ruthenium hexafluoride has unique importance in materials science, chemical research, and industrial applications. Especially in the semiconductor manufacturing industry, it is used as an etchant to finely remove unwanted material layers on silicon wafers, ensuring high-precision pattern transfer during chip manufacturing. Additionally, due to the good thermal stability and chemical stability of RuF6, it is also applied in surface treatment processes, such as improving the wear resistance and corrosion resistance of materials. At the same time, in some advanced energy conversion devices such as fuel cells, RuF6 can also be used as a catalyst precursor to help improve catalytic efficiency and extend service life.

[0003] Currently, the synthesis method of ruthenium hexafluoride mainly relies on chemical reactions under high temperature and high pressure. The most common route is to react metallic ruthenium powder or ruthenium compounds with a lower valence state with excessive fluorine gas under certain conditions. However, in this method, due to the excessive fluorine gas contacting and reacting with metallic ruthenium in a short time, the reaction is violent, it is difficult to control the reaction rate, and the by-products may increase. In addition, electrochemical fluorination can also be used. Summary of the Invention

[0004] Aiming at the problems in the preparation of ruthenium hexafluoride in the prior art, such as violent reaction and many side reactions due to the direct use of fluorine gas, this application proposes a method for synthesizing ruthenium hexafluoride.

[0005] The technical solution of this application is as follows:

[0006] A method for synthesizing ruthenium hexafluoride, comprising the following steps:

[0007] Step S1. Add metallic ruthenium to the reactor, heat it while purging the reactor with an inert gas and then evacuating it, and repeat the purging and evacuation.

[0008] Step S2. Continue to raise the temperature to 450 - 700 °C, and then introduce into the reactor any one of a mixed gas of fluorine gas and nitrogen gas, and nitrogen trifluoride, react with metallic ruthenium to generate crude ruthenium hexafluoride, and finally collect the refined ruthenium hexafluoride at a low temperature.

[0009] Preferably, the heating temperature in step S1 is 200 - 400 °C, and the water content of the inert gas < 5 ppm.

[0010] Preferably, the purity of the metallic ruthenium in step S1 ≥ 95%.

[0011] Preferably, the rate of inert gas purging in step S1 is 50-200 mL / min.

[0012] Preferably, in step S2, nitrogen trifluoride is introduced at a molar ratio of nitrogen trifluoride to ruthenium metal of (2-4.5):1, and the introduction rate is 40-220 mL / min; nitrogen trifluoride is first cracked into nitrogen and fluorine, and then fluorine reacts with ruthenium metal to form ruthenium hexafluoride.

[0013] Preferably, in step S2, a mixed gas of fluorine and nitrogen is introduced at a molar ratio of the mixed gas of fluorine and nitrogen to ruthenium metal of (3-6.5):1, and the introduction rate is 40-220 mL / min; wherein, the volume ratio of fluorine to nitrogen is 1:(0.5-2).

[0014] Preferably, in step S2, the water content of both the mixed gas of fluorine and nitrogen and nitrogen trifluoride is <5 ppm.

[0015] Preferably, in step S2, the reaction duration is 1-25 min, and the reaction pressure is 0-1 MPa.

[0016] Preferably, in step S2, the temperature for low-temperature collection is -70-10°C.

[0017] Preferably, in step S1, the material of the reactor is any one of stainless steel, nickel, Monel alloy or Hastelloy alloy.

[0018] Advantages of the present application:

[0019] (1) The present application improves the reaction efficiency and product quality. By strictly controlling the inert gas purging rate (50-200 mL / min) and the gas introduction rate (40-220 mL / min), the high purity of the reaction environment is ensured, the formation of by-products is reduced, and thus the purity of the final product is improved. Setting the parameter ranges (200-400°C for step S1, 450-700°C, pressure (0-1 MPa) and reaction time (1-25 min) for step S2) enables the reaction to proceed stably while ensuring the effective formation of ruthenium hexafluoride.

[0020] (2) Enhance operation safety

[0021] Avoid directly using dangerous fluorine gas, which has a violent reaction and an increase in by-products; and reduces the possibility of equipment corrosion. Purging the reactor with high-purity inert gas at the beginning of the reaction effectively removes moisture and oxygen in the air, prevents the oxidation of ruthenium metal, and also provides a safe anaerobic environment for the subsequent reaction.

[0022] (3) Easy to scale up production

[0023] This application allows for the selection of different fluorine sources (a mixture of fluorine gas and nitrogen gas or nitrogen trifluoride) according to actual needs, and optimizes the reaction effect by adjusting the gas ratio, making it suitable for industrial production of different scales. The low-temperature collection method at -70 to 10 °C not only helps to improve the product yield but also ensures that ruthenium hexafluoride is stably preserved in solid form, facilitating subsequent processing and transportation.

[0024] In summary, the ruthenium hexafluoride synthesis method provided by this application not only improves the safety and efficiency of the reaction but also ensures the consistency and high quality of the product, providing reliable raw material support for multiple fields such as semiconductor manufacturing, surface treatment, and energy conversion devices. In addition, this method is easy to implement and has good economic efficiency, making it suitable for large-scale industrial applications. Detailed implementation manners

[0025] To further elaborate on the technical means and effects adopted by this application to achieve the predetermined invention purpose, the following combines preferred embodiments to detail the specific implementation manners, structures, features, and their effects according to this application as follows.

[0026] Example 1

[0027] This application provides a method for synthesizing ruthenium hexafluoride, which is as follows:

[0028] Step S1. After adding ruthenium powder with a purity of 98% to a stainless-steel reactor, under the purge of helium gas (water content < 0.5 ppm) at 400 °C, the purge rate is 50 mL / min, and evacuation and replacement are performed 3 times to remove impurities such as water and oxygen in the system;

[0029] Step S2. Under the condition of a high temperature of 550 °C, nitrogen trifluoride (water content < 1 ppm) is introduced at a rate of 40 mL / min to crack and generate fluorine gas and strip-shaped metallic ruthenium. The reaction pressure is controlled at 0 MPa, and the molar ratio of nitrogen trifluoride to ruthenium is 2.5:1; the generated fluorine gas reacts with the ruthenium in the reactor to generate ruthenium hexafluoride, and the reaction time is controlled at 5 min to ensure full reaction without the generation of other valence fluoride compounds; finally, ruthenium hexafluoride is collected in a low-temperature collector at 10 °C, and ruthenium hexafluoride products with a purity of 99.9% can be collected.

[0030] Example 2

[0031] This application provides a method for synthesizing ruthenium hexafluoride, which is as follows:

[0032] Step S1. After adding massive metallic ruthenium with a purity of 99% to a nickel reactor, under the purge of nitrogen gas (water content < 1 ppm) at 200 °C, the purge rate is 100 mL / min, and evacuation and replacement are performed 3 times to remove water and oxygen and other impurity gases in the reaction system;

[0033] Step S2. Under the condition of a high temperature of 500 °C, nitrogen trifluoride (with water content < 0.1 ppm) is introduced at a rate of 100 mL / min. It decomposes to generate fluorine gas, which reacts with irregular ruthenium metal blocks. The amount of substance of nitrogen trifluoride introduced is 3 times that of ruthenium, and the reaction pressure is controlled at 0.1 MPa. The generated fluorine gas reacts with ruthenium in the reactor to generate ruthenium hexafluoride. The reaction time is controlled at 6 minutes to ensure complete reaction without the formation of other valence fluoride compounds. Finally, ruthenium hexafluoride is collected in a low-temperature collector at -20 °C, and ruthenium hexafluoride products with a purity of 99% are collected.

[0034] Example 3

[0035] This application provides a method for synthesizing ruthenium hexafluoride, which is as follows:

[0036] Step S1. After adding granular metallic ruthenium with a purity of 95.5% to a Monel alloy reactor, under the purge of nitrogen gas (with water content < 0.2 ppm) at 350 °C, the purge rate is 150 mL / min, and it is evacuated and replaced several times to remove impurities such as water and oxygen in the system.

[0037] Step S2. Under the condition of a high temperature of 450 °C, nitrogen trifluoride (with water content < 0.1 ppm) is introduced at a rate of 150 mL / min. It decomposes to generate fluorine gas and granular metallic ruthenium. The amount of substance of nitrogen trifluoride introduced is 3.5 times that of ruthenium, and the reaction pressure is controlled at 0.2 MPa. The generated fluorine gas reacts with ruthenium in the reactor to synthesize ruthenium hexafluoride. The reaction time is controlled at 6.5 minutes to ensure complete reaction without the formation of other valence fluoride compounds.

[0038] Finally, ruthenium hexafluoride is collected in a low-temperature collector at -25 °C, and ruthenium hexafluoride products with a purity of 99.4% can be collected.

[0039] Example 4

[0040] This application provides a method for synthesizing ruthenium hexafluoride, which is as follows:

[0041] Step S1. After adding irregular strip-shaped metallic ruthenium with a purity of 96% to a Hastelloy alloy reactor, under the purge of nitrogen gas (with water content < 0.2 ppm) at 250 °C, the purge rate is 200 mL / min, and it is evacuated and replaced 3 times to remove impurities such as water and oxygen in the system.

[0042] Step S2. Under the condition of 700 °C high temperature, nitrogen trifluoride (with water content < 0.2 ppm) is introduced at a rate of 40 mL / min, and the rate is 220 mL / min. It reacts with the ruthenium powder generated by cracking to form fluorine gas. The amount of substance of nitrogen trifluoride introduced is 4.5 times that of ruthenium, and the reaction pressure is controlled at 1 MPa. The generated fluorine gas reacts with the ruthenium in the reactor to form ruthenium hexafluoride. The reaction time is controlled at 20 min to ensure full reaction without the formation of other valence fluoride compounds. Finally, ruthenium hexafluoride is collected in a low-temperature collector at -70 °C, and ruthenium hexafluoride products with a purity of 99.6% are collected.

[0043] Example 5

[0044] This application provides a method for synthesizing ruthenium hexafluoride, which is specifically as follows:

[0045] Step S1. After adding irregular strip-shaped metallic ruthenium with a purity of 96% to a Hastelloy reactor, under the purge of nitrogen (with water content < 0.2 ppm) at 250 °C, the purge rate is 200 mL / min, and it is evacuated and replaced 3 times to remove impurities such as water and oxygen in the system.

[0046] Step S2. Under the condition of 600 °C high temperature, a mixed gas of fluorine gas and nitrogen gas (the volume ratio of fluorine gas to nitrogen gas is 1:0.5, and the water content rates of both fluorine gas and nitrogen gas are less than 5 ppm) is introduced. The molar ratio of the mixed gas of fluorine gas and nitrogen gas to metallic ruthenium is 5:1. The rate of the mixed gas is 100 mL / min, and the reaction pressure is controlled at 1 MPa. The generated fluorine gas reacts with the ruthenium in the reactor to form ruthenium hexafluoride. The reaction time is controlled at 25 min to ensure full reaction without the formation of other valence fluoride compounds. Finally, ruthenium hexafluoride is collected in a low-temperature collector at -70 °C, and ruthenium hexafluoride products with a purity of 99.6% are collected.

[0047] Example 6

[0048] The distinguishing technical feature of this example from Example 5 is that a mixed gas of fluorine gas and nitrogen gas (the volume ratio of fluorine gas to nitrogen gas is 1:1.5, and the water content rates of both fluorine gas and nitrogen gas are less than 0.05 ppm) is introduced. The molar ratio of the mixed gas of fluorine gas and nitrogen gas to metallic ruthenium is 3:1. Ruthenium hexafluoride products with a purity of 99.6% are collected.

[0049] Example 7

[0050] The distinguishing feature of this example from Example 5 is that a mixed gas of fluorine gas and nitrogen gas (the volume ratio of fluorine gas to nitrogen gas is 1:2, and the water content rates of both fluorine gas and nitrogen gas are less than 0.05 ppm) is introduced. The molar ratio of the mixed gas of fluorine gas and nitrogen gas to metallic ruthenium is 6:1. Ruthenium hexafluoride products with a purity of 99.6% are collected.

[0051] Comparative Example 1

[0052] The distinguishing technical feature between this comparative example and Example 1 is that nitrogen trifluoride is replaced with fluorine gas. A ruthenium hexafluoride product with a purity of 80.7% is collected.

[0053] Comparative Example 2

[0054] The distinguishing technical feature between this comparative example and Example 1 is that the temperature increase in step S2 is 900 °C. A ruthenium hexafluoride product with a purity of 85.4% is collected.

[0055] Comparative Example 3

[0056] The distinguishing technical feature between this comparative example and Example 1 is that the temperature increase in step S2 is 400 °C. A ruthenium hexafluoride product with a purity of 81.9% is collected.

[0057] It can be seen from Examples 1 to 7 and Comparative Examples 1 to 3 that by using the method of the present application, under suitable reaction parameter conditions, using nitrogen trifluoride or a mixture of nitrogen and fluorine gas as the fluorine source has the characteristics of few by-products, controllable product quality, and high product yield.

[0058] As mentioned above, it is only the preferred embodiments of the present application, and there is no any formal limitation to the present application. Although the present application has been disclosed as above with the preferred embodiments, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to equivalent embodiments with equivalent changes within the scope of the technical solution of the present application. However, as long as it does not depart from the content of the technical solution of the present application, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application still fall within the scope of the technical solution of the present application.

Claims

1. A method for synthesizing ruthenium hexafluoride, characterized in that: The steps include: Step S1. adding metallic ruthenium to a reactor, purging the reactor with an inert gas while heating, and then evacuating the reactor, and repeating the purging and evacuating; Step S2. Continue to raise the temperature to 450-700°C, then introduce a mixed gas of fluorine and nitrogen, or nitrogen trifluoride into the reactor to react with metallic ruthenium to generate crude ruthenium hexafluoride, and finally collect the refined ruthenium hexafluoride at low temperature.

2. The method for synthesizing ruthenium hexafluoride according to claim 1, characterized in that: In the step S1, the heating temperature is 200-400° C., and the water content of the inert gas is less than 5 ppm.

3. The method for synthesizing ruthenium hexafluoride according to claim 1, characterized in that: The purity of the metallic ruthenium in step S1 is ≥95%.

4. The method for synthesizing ruthenium hexafluoride according to claim 1, characterized in that: The inert gas purging rate in step S1 is 50-200 mL / min.

5. The method for synthesizing ruthenium hexafluoride according to claim 1, characterized in that: In the step S2, nitrogen trifluoride is introduced at a molar ratio of nitrogen trifluoride to metal ruthenium of (2-4.5):1 at a rate of 40-220 mL / min; the nitrogen trifluoride is first cracked into nitrogen and fluorine, and the fluorine reacts with metal ruthenium to generate ruthenium hexafluoride.

6. The method for synthesizing ruthenium hexafluoride according to claim 1, characterized in that: In the step S2, a mixed gas of fluorine and nitrogen is introduced at a molar ratio of (3-6.5) to metallic ruthenium at a rate of 40-220 mL / min; wherein the volume ratio of fluorine to nitrogen is 1:(0.5-2).

7. The method for synthesizing ruthenium hexafluoride according to claim 1, characterized in that: In the step S2, the water content of the mixed gas of fluorine gas and nitrogen gas and the nitrogen trifluoride is less than 5 ppm.

8. The method for synthesizing ruthenium hexafluoride according to claim 1, characterized in that: In step S2, the reaction time is 1 to 25 minutes, and the reaction pressure is 0 to 1 MPa.

9. The method for synthesizing ruthenium hexafluoride according to claim 1, characterized in that: In step S2, the temperature of low temperature collection is -70 to 10°C.

10. The method for synthesizing ruthenium hexafluoride according to claim 1, characterized in that: In the step S1, the material of the reactor is any one of stainless steel, nickel, monel alloy or hastelloy alloy.