Process for producing trifluoroamine oxide

Abstract

A method for producing trifluoroamine oxide is disclosed. According to one embodiment, the method includes the steps of simultaneously introducing nitrogen trifluoride and nitrous oxide into a reaction system under an SbF5 reaction catalyst to produce an intermediate product, and reacting the intermediate product with potassium fluoride to produce trifluoroamine oxide. The step of reacting the intermediate product with potassium fluoride is carried out at atmospheric pressure and room temperature.

Description

Technical Field

[0001] The present invention relates to a method for producing trifluoroamine oxide (F3NO).

Background Art

[0002] CVD (Chemical Vapor Deposition) process technology is widely known as a thin film manufacturing process for semiconductor device manufacturing. When forming a thin film of a semiconductor device in a CVD chamber, it is preferable that the thin film is formed only on the target object in the CVD chamber, but the thin film forming material will also be deposited on other exposed surfaces in the CVD chamber unnecessarily. For example, the thin film forming material is also deposited on the wall surface in the chamber, the product fixing jig, the pipe, etc. Also, during the CVD process, substances deposited other than the target object may peel off and contaminate the surface of the thin film deposited on the target object or the surface of the target object on which the thin film is formed. Such contamination causes defects in semiconductor devices and is a factor in reducing the yield. Therefore, a cleaning process for removing unnecessary deposits deposited in the chamber at an appropriate cycle is performed. Such a cleaning process in the CVD chamber is performed manually or using a cleaning gas.

[0003] Several basic physical properties are required for the cleaning gas of the CVD chamber. First, the cleaning gas must be able to clean the inside of the CVD chamber within a short time and must not generate harmful substances. And it must be an environmentally friendly gas. Conventional perfluorides such as CF4, C2F6, SF6, and NF3 have been used as the cleaning gas for the chamber or the etching gas for the deposited thin film in the manufacturing process of semiconductors or electronic devices. In particular, in the case of nitrogen trifluoride (NF3) gas, it is widely used as a cleaning gas worldwide.

[0004] However, such perfluorinated substances are stable and remain in the atmosphere for a very long time. In addition, the waste gas after use contains a very high concentration of non-decomposed perfluorinated substances, so it is very costly to treat such waste gas below the allowable standard value and release it into the atmosphere. Furthermore, such ordinary perfluorinated substances are known to have very high Global Warming Potential (GWP) values (ITH 100 years, CO2 equivalent, CF4 9,200, SF6 23,900, NF3 17,200). Therefore, such gases impose a considerable burden on the environment. Thus, there is a very high demand for alternative gases with low GWP values used in the etching or cleaning process. Also, even if the cleaning or etching gas itself is environmentally friendly, it may decompose during the cleaning or etching process and become harmful gases such as CF4 and NF3, which may remain in the atmosphere for a long time when discharged.

[0005] In particular, nitrogen trifluoride (NF3) gas not only has a large global usage but also has a very high global warming potential. Therefore, reducing the environmental burden and developing substances that can reduce the usage and replace NF3 gas are required for the sustainable development of the semiconductor industry.

[0006] Among such alternative gas candidates, trifluoroamine oxide (F3NO) can be easily decomposed in an aqueous solution, has an extremely low predicted GWP, and can replace NF3, which is currently used as a cleaning gas in terms of performance. F3NO has a very high "F" content that affects etching and cleaning performance. Different from PFC, HFC, NF3, and SF6, which are hardly decomposable, it can be easily decomposed by acidic and alkaline aqueous solutions. Therefore, it is estimated that its global warming index is close to 0, and it is expected that the energy and environmental burden required for the decomposition treatment of unreacted residual F3NO are small. It is also non-irritating in case of leakage and exhibits physical properties similar to NF3 at room temperature. Therefore, in primary considerations, it has very high potential as an alternative gas.

[0007] However, information regarding the production method of trifluoroamine oxide (F3NO), which is an alternative gas candidate substance, is extremely limited.

[0008] Patent Document 1 (US Published Patent 2003 / 0143846A1) discloses a gas composition containing F3NO as a gas composition for cleaning the inside of a reactor and etching a film of a silicon-containing compound. Regarding the method for synthesizing F3NO, under an SbF5 catalyst, NF3 and N2O are reacted at a temperature of 150 °C to synthesize an NF2OSb2F 11 salt, and then a method of thermally decomposing it at a high temperature (>200 °C) to obtain F3NO is disclosed. However, the yield with respect to the raw materials NF3 and N2O is about 20%, which is extremely low, and the purity is not even mentioned. Also, considering based on another raw material SbF5 to be input, the yield is about 33%, which is very low. Synthesizing F3NO using the SbF5 / NF3 / N2O reaction system has not been sufficiently investigated in terms of the synthesis method, risks, yield, gas purity, etc. as described above, and it is not clear whether it is a commercially applicable method.

[0009] The applicant of the present invention presented new methods in Patent Document 2 (Korean Registered Patent 10-2010460B1) and Patent Document 3 (Korean Registered Patent 10-2010466B1) respectively, which can produce trifluoroamine oxide with high yield and purity while using the same SbF5 / NF3 / N2O reaction system as in Patent Document 1. For example, according to the method disclosed in Patent Document 2, NF3 and N2O are reacted under SbF5 to obtain an intermediate product NF2OSbF6, and trifluoroamine oxide (F3NO) is synthesized through a two-step reaction of contacting this intermediate product with NaF and performing a thermal decomposition reaction in a vacuum atmosphere. And according to the method disclosed in Patent Document 3, NF3 and N2O are reacted under SbF5 to obtain an intermediate product NF2OSbF6, but the reaction gas containing nitrogen (N2) generated in this reaction is removed, nitrogen trifluoride and nitrous oxide are additionally input to produce the intermediate product, and trifluoroamine oxide (F3NO) is synthesized through a two-step reaction of reacting this intermediate product with NaF.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0011] However, according to the synthesis methods of trifluoroamine oxide disclosed in Patent Documents 2 and 3 described above, for the reaction in the second step of reacting the intermediate product with NaF, it is necessary to heat to a temperature of about 150°C to 200°C under a vacuum atmosphere. As a result, not only an expensive reactor capable of a vacuum process must be used, but also a heating process becomes essential due to thermal decomposition, which is a factor increasing the manufacturing cost of trifluoroamine oxide. In addition, the progress rate of the thermal decomposition reaction is slow and it takes a considerable amount of time for the thermal decomposition reaction, so the productivity is not high.

[0012] Therefore, one problem to be solved by the present invention is to provide a method for producing trifluoroamine oxide that can reduce the manufacturing cost and has high productivity in the manufacturing process of trifluoroamine oxide using an SbF5 / NF3 / N2O reaction system.

Means for Solving the Problems

[0013] A method for producing trifluoroamine oxide according to an embodiment of the present invention for solving such problems includes a step of simultaneously introducing nitrogen trifluoride and nitrous oxide under a reaction catalyst of SbF5 and reacting them to produce an intermediate product, and a step of reacting the intermediate product with potassium fluoride to produce trifluoroamine oxide.

[0014] According to one aspect of the above embodiment, the step of reacting the intermediate product with potassium fluoride can be carried out under atmospheric pressure and normal temperature conditions.

Effect of the Invention

[0015] According to an embodiment of the present invention, in the manufacturing process of trifluoroamine oxide using the SbF5 / NF3 / N2O reaction system, when synthesizing trifluoroamine oxide by decomposing the intermediate product NF2OSbF6, instead of the existing sodium fluoride, potassium fluoride is reacted with NF2OSbF6. Therefore, a vacuum device and an additional heating process are not required, and the reaction occurs spontaneously under atmospheric pressure and normal temperature. Thus, not only can the manufacturing cost be reduced, but also the productivity can be improved.

Brief Description of the Drawings

[0016]

Figure 1

Modes for Carrying Out the Invention

[0017] Hereinafter, with reference to the drawings, preferred embodiments and examples of the present invention will be described. However, the following embodiments and examples are merely illustrative of the preferred configurations of the present invention, and the scope of the present invention is not limited to these configurations. In the following description, the hardware configuration, software configuration, processing flow, manufacturing conditions, size, material, shape, etc. of the device are not intended to limit the scope of the present invention to these unless specifically described otherwise.

[0018] According to the method for producing trifluoroamine oxide according to the embodiment of the present invention described below, in the process of synthesizing trifluoroamine oxide using the reaction system of SbF5 / NF3 / N2O disclosed in Patent Document 2 and Patent Document 3 mentioned above, when decomposing the intermediate product NF2OSbF6 to synthesize trifluoroamine oxide, instead of sodium fluoride (NaF) that requires heating at about 150°C to 200°C under vacuum as the reactant to react with NF2OSbF6, potassium fluoride (KF) that undergoes a spontaneous reaction even at atmospheric pressure and normal temperature is used. According to this, a vacuum facility is not required as a reactor, and additional heating is not required for the reaction, so the manufacturing cost can be reduced. Also, the reaction rate is fast and the productivity can be improved.

[0019] Figure 1 is a flowchart showing a method for producing trifluoroamine oxide according to an embodiment of the present invention.

[0020] Referring to Figure 1, the method for producing trifluoroamine oxide according to an embodiment of the present invention includes a step S10 of simultaneously introducing nitrogen trifluoride and nitrous oxide and reacting them under a reaction catalyst of SbF5 to produce an intermediate product, and a step S20 of reacting the intermediate product with potassium fluoride to produce trifluoroamine oxide. At this time, the step of reacting the intermediate product with potassium fluoride can be carried out under conditions of atmospheric pressure and normal temperature.

[0021] Hereinafter, the method for producing trifluoroamine oxide according to this embodiment will be described in detail for each step.

[0022] First, the method for producing trifluoroamine oxide according to an embodiment of the present invention includes step S10 of reacting nitrogen trifluoride and nitrous oxide under a reaction catalyst to produce an intermediate product.

[0023] In the step of producing the intermediate product, the reaction of the following reaction formula 1 or reaction formula 2 is carried out, or the reactions of reaction formulas 1 and 2 are carried out simultaneously. In reaction formulas 1 and 2, the reaction catalyst is SbF5. An example of the reaction formula using the reaction catalyst is represented by the following reaction formulas 1 and 2.

[0024] <Reaction formula 1>

[0025] NF3 + N2O + SbF5 → NF2OSbF6 + N2

[0026] <Reaction formula 2>

[0027] NF3 + N2O + 2SbF5 → NF2OSb2F 11 + N2

[0028] In step S10 of producing the intermediate product, the generated nitrogen (N2) and the reaction gas mixed therewith are removed, and pure nitrogen trifluoride and nitrous oxide are additionally introduced, so that the reaction time can be reduced.

[0029] In step S10 of producing the intermediate product, as the reactions of reaction formula 1 and reaction formula 2 proceed, the reaction rate becomes slower, and finally the reaction time becomes extremely long, 80 hours or more. To solve such problems, during the reaction in step S10 of producing the intermediate product, nitrogen (N2) and the reaction gas mixed therewith are removed, and pure nitrogen trifluoride and nitrous oxide are additionally introduced, so that the reaction time can be reduced by 80% or more, preferably 85% or more, compared with the prior art, and can be set to 8 to 10 hours.

[0030] Also, in step S10 of manufacturing the intermediate product, nitrogen trifluoride and nitrous oxide can be separated from the mixture of nitrogen and reaction gas and reused. For example, nitrogen can be removed from the removed mixture of nitrogen and reaction gas by a distillation process, nitrogen trifluoride and nitrous oxide can be separated and recycled, and reused in the reaction of step S10 for manufacturing the intermediate product. The recycling cycle is preferably at a conversion rate of 40% to 95% based on the initial and residual SbF5, more preferably 50% to 90%, and even more preferably 60% to 85%. The time taken to reach the conversion rate in the reaction is no more than 2 to 3 hours, and the reaction time to achieve an overall conversion rate of 100% can be shortened to within 10 hours.

[0031] In this way, during the reaction of step S10 for manufacturing the intermediate product, by removing nitrogen and the reaction gas and additionally introducing pure nitrogen trifluoride and nitrous oxide, or nitrogen trifluoride and nitrous oxide recovered from the mixture of nitrogen and the reaction gas, the reaction time can be epoch-makingly shortened. Also, the size of the reactor for manufacturing the same amount of trifluoroamine oxide can be reduced to about 1 / 8 to 1 / 20, and there is an excellent effect in productivity.

[0032] At this time, the reaction ratio of the reaction catalyst, nitrogen trifluoride, and nitrous oxide in step S10 of producing the intermediate product is preferably 2:1 to 10:1 to 10 in terms of molar ratio, more preferably 2:1 to 5:1 to 5 in terms of molar ratio, even more preferably 2:2 to 5:2 to 5 in terms of molar ratio, and most preferably 2:3 to 5:3 to 5 in terms of molar ratio. The reaction ratio of the reaction catalyst, nitrogen trifluoride, and nitrous oxide is basically 2:1:1 in terms of the number of moles, and the ratio of nitrogen trifluoride and nitrous oxide can be 1 molar ratio to 10 molar ratios respectively. If the reaction ratio of the reaction catalyst, nitrogen trifluoride, and nitrous oxide is less than the molar ratio of 2:1:1 (when the ratio of nitrogen trifluoride and nitrous oxide is less than 1 molar ratio respectively), reaction catalysts such as unreacted SbF5 with strong moisture absorbency and fuming properties will remain, which will act as impurities in the subsequent trifluoroamine oxide production reaction, and there is a problem that the work becomes very difficult due to heat generation and the generation of fume during the grinding process. When it exceeds 2:10:10 (when the ratio of nitrogen trifluoride and nitrous oxide exceeds 10 molar ratios respectively), the reaction pressure is too high, the production cost of the reactor increases, and the explosion risk during the reaction increases. As the molar ratio, 2:2:2 (reaction catalyst: nitrogen trifluoride: nitrous oxide) is preferable, and 2:1.2:2 is even more preferable. The reason is that when the intermediate product NF2O-salt is generated, first, the reaction catalyst and nitrogen trifluoride (NF3) generate a primary salt by a chlorination reaction, and then nitrous oxide (N2O) reacts. Therefore, it is preferable to introduce a slightly excessive amount of nitrous oxide (N2O) with relatively poor reactivity.

[0033] Also, the reaction in step S10 of producing the intermediate product is preferably carried out in the temperature range of 110°C to 150°C, more preferably in the temperature range of 120°C to 150°C, and most preferably in the temperature range of 130°C to 150°C. If the reaction temperature is less than 110°C, it is close to the melting point of the generated intermediate product NF2O-salt, and solid-phase NF2O-salt is precipitated, making stirring difficult, and the absorption of gaseous NF3 and N2O slow, resulting in the problem that the reaction does not proceed smoothly. If the reaction temperature exceeds 150°C, a partial decomposition reaction may occur, and the raw materials NF3 and N2O may be regenerated, or by-products such as NO and NO2 may be generated, which causes a decrease in yield. Also, when the reaction temperature is high, high pressure is applied to the reactor, the vapor pressures of the raw materials NF3 and N2O also increase, the absorption degree for the liquid reaction catalyst decreases, and an increase in the production cost of the reactor and a decrease in the reaction rate occur.

[0034] The reactions of reaction formula 1 and reaction formula 2 in step S10 of producing the intermediate product are gas-phase - liquid-phase reactions. That is, instead of a gas-phase - gas-phase reaction, NF3 and N2O, which are gaseous raw materials, are absorbed by the liquid-phase intermediate catalyst SbF5 and a neutralization reaction occurs. Therefore, it is preferable to maintain the reaction temperature at a temperature lower than 149.5°C, which is the boiling point of SbF5, and it is important to maintain the minimum temperature at which smooth stirring is possible.

[0035] Furthermore, the reaction in step S10 of producing the intermediate product can be carried out in a suitable high-pressure reactor. Preferably, a reactor including anchor type stirring means with a size of 1 / 2 of the inner diameter of the reactor can be used. In order to enhance the absorption of NF3 and N2O by the reactor and make the reaction proceed smoothly, it is preferable to carry out stirring at a rotation speed of 50 rpm to 800 rpm, more preferably at a rotation speed of 100 rpm to 500 rpm, and most preferably at a rotation speed of 200 rpm to 400 rpm. When the stirring speed is less than 50 rpm, the absorption rate of NF3 and N2O, which are gaseous raw materials in the gas-liquid reaction, is slow, the reaction progress is slow, and there are problems of an increase in the size of the reactor and a decrease in productivity. When the stirring speed exceeds 800 rpm, problems such as mechanical wear due to high-speed stirring occur, and there is a problem of an increase in maintenance costs.

[0036] As the stirrer, types such as Grand seal, mechanical seal, and magnetic drive can be used. Considering that it is a high-temperature and high-pressure reaction, it is preferable to use magnetic drive. Examples of the material of the reactor used in the reaction include stainless steel, Hastelloy, and alloys. When using something like stainless steel, it is preferable to carry out passivation using fluorine (F2) gas before use.

[0037] Also, in step S10 of producing the intermediate product, it is preferable to simultaneously introduce and react nitrogen trifluoride and nitrous oxide under a reaction catalyst, or first introduce and react nitrogen trifluoride, and then sequentially introduce and react nitrous oxide. When nitrous oxide is first introduced and reacted under a reaction catalyst, and then nitrogen trifluoride is sequentially introduced and reacted, the reaction rate becomes extremely slow, a long-term reaction is required, and there is also a problem that its yield is very low.

[0038] Furthermore, the progress of the reaction in step S10 of producing the intermediate product can be calculated by tracking nitrogen trifluoride (NF3), nitrous oxide (N2O), which are the raw material gases consumed, and nitrogen (N2), which is the gas produced, using gas chromatography. Usually, the analysis is carried out after calibration with a standard gas.

[0039] Specifically, in the step of producing the intermediate product, the step of tracking and analyzing the ratios of nitrogen trifluoride and nitrous oxide consumed and the ratio of nitrogen produced by using one or more of gas chromatography TCD, 5% fluorocol / carbopack B column, and molecular sieve capillary column during the reaction can be further included.

[0040] Next, the method for producing trifluoroamine oxide according to an embodiment of the present invention includes step S20 of reacting the intermediate product with potassium fluoride to produce trifluoroamine oxide. Such a reaction between the intermediate product and potassium fluoride proceeds spontaneously even under atmospheric pressure and normal temperature conditions.

[0041] In step S20 of producing the trifluoroamine oxide (F3NO), the reaction of the following reaction formula 3 or reaction formula 4 may be carried out, or the reactions of reaction formulas 3 and 4 may be carried out simultaneously.

[0042] <Reaction formula 3>

[0043] NF2OSbF6 + KF → F3NO + KSbF6

[0044] <Reaction formula 4>

[0045] NF2OSb2F 11 + KF → F3NO + 2KSbF6

[0046] At this time, the reaction ratio of the intermediate product and potassium fluoride in step S20 for producing the trifluoroamine oxide is preferably a molar ratio of 1:1 to 4. The reaction in the step of producing trifluoroamine oxide is a solid-solid reaction. Therefore, the contact between the solid-solid surfaces is very important. In the reaction according to the present invention, the reaction molar ratio of the reactants NF2O-salt and potassium fluoride (KF) is preferably a molar ratio of 1.0 to 4.0 based on potassium fluoride. When the input amount of potassium fluoride is less than 1.0 mol, it is difficult to complete the reaction. When it exceeds 4.0 mol, the amount of the input solid increases, which may cause problems in stirring. In order to activate the reaction in the solid-solid reaction, a uniform mixing of NF2O-salt and KF is important. If sufficient contact cannot be achieved due to problems such as stirring, the yield of trifluoroamine oxide (F3NO) will be extremely low. In order to increase the contact between the reactants, it is preferable to sufficiently pulverize and mix NF2O-salt and KF to start the reaction. More preferably, the smooth progress of the reaction can be expected by forming pellets after mixing the raw materials.

[0047] Also, in step S20 for producing the trifluoroamine oxide, the reaction proceeds spontaneously even at atmospheric pressure and room temperature. Therefore, there is no need to put the reactor under vacuum or reduced pressure conditions or to additionally heat it for the reaction.

[0048] Furthermore, the degree of progress of the reaction in step S20 for producing trifluoroamine oxide can be calculated by tracking the consumed gas material with gas chromatography. Usually, the analysis is performed after calibration with a standard gas.

[0049] Specifically, in step S20 of manufacturing trifluoroamine oxide, a step of tracking and analyzing the proportions of generated F3NO and by-products (NF3, N2O, and NO) can be further included by using one or more of gas chromatography TCD, 5% fluorocol / carbopack B column, and molecular sieve capillary column during the reaction.

[0050] Although not shown in FIG. 1, KSbF6 obtained as a by-product in step S20 of manufacturing trifluoroamine oxide can be thermally decomposed to recover SbF5, which can also be used as a reaction catalyst in step S10 of manufacturing the next intermediate product. Thereby, the usage amount of SbF5 can be reduced, and the manufacturing cost can be further lowered.

[0051] As described above, the above description is merely an example and should not be construed as being limited thereby. The technical idea of the present invention must be specified only by the invention described in the claims, and all technical ideas within the equivalent scope thereof must be construed as being included in the scope of rights of the present invention. It is obvious to those skilled in the art that the present invention can be embodied with the foregoing examples being modified in various forms.

Claims

1. SbF 5 A step of simultaneously introducing nitrogen trifluoride and nitrous oxide under a reaction catalyst of SbF 5 to cause a reaction to produce an intermediate product, and a step of reacting the intermediate product with potassium fluoride to produce trifluoroamine oxide. A method for producing trifluoroamine oxide comprising these steps.

2. The method for producing the trifluoroamine oxide according to claim 1, wherein the reaction between the intermediate product and the potassium fluoride is carried out under atmospheric pressure and normal temperature conditions.

3. KSbF obtained as a by-product in the step of producing the trifluoroamine oxide 6 is pyrolyzed to recover SbF 5 and further comprises a step of recovering The recovered SbF 5 The method for producing a trifluoroamine oxide according to claim 1, wherein the recovered SbF 5 is used as a reaction catalyst in the step of producing the following intermediate product.

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