KR20220040750A - Apparatus for producing nitrogen trifluoride - Google Patents

Abstract

A device for manufacturing nitrogen trifluoride of the present invention includes: a plurality of electrolyzers in which an electrolysis reaction of ammonia (NH_3)-hydrogen fluoride (HF)-based molten salt to nitrogen trifluoride occurs; and a DC power supply unit for supplying DC power to the plurality of electrolyzers by converting AC power into DC power.

Description

Nitrogen trifluoride manufacturing equipment {APPARATUS FOR PRODUCING NITROGEN TRIFLUORIDE}

The present invention relates to an apparatus for producing nitrogen trifluoride, and more particularly, to an apparatus for producing nitrogen trifluoride having a structure in which a plurality of electrolyzers are connected to one DC power supply unit.

Nitrogen trifluoride (NF ₃ ) is a colorless gas having a boiling point of about -129 ° C and a melting point of about -208 ° C. Silicon, polysilicon, Si ₃ N ₄ , WSi ₂ , MoSi ₂ used in semiconductor devices, etc. It is used as a gas for dry etching of materials, a cleaning gas for chemical vapor deposition (CVD) equipment, and the like.

As a method for producing nitrogen trifluoride gas, a two-step reaction method and a one-step reaction method are known.

In the two-step reaction method, in the first step reaction, hydrogen fluoride (HF) is electrolyzed to obtain fluorine gas (F ₂ ), and in the second step reaction, fluorine gas and a nitrogen-containing compound obtained in the first step reaction (for example, , NH ₃ ) is directly reacted to produce nitrogen trifluoride gas.

The one-step reaction method uses a molten salt containing a nitrogen component (eg, NH ₃ ) and a fluorine component (eg, HF) as an electrolytic solution to produce nitrogen trifluoride by electrolysis.

Compared to the two-step reaction method, the one-step reaction method has the advantage of being easily synthesized in one step and capable of producing high-purity nitrogen trifluoride in a relatively high yield.

In the conventional nitrogen trifluoride production apparatus used in the one-step reaction method, 200 to 400 V AC electricity, which is an industrial AC power source, is supplied to an electrolytic cell in which the electrolysis reaction of ammonia-hydrogen fluoride-based molten salt occurs by a rectifier, and direct current electricity of about 8 V was converted to and supplied. In particular, when an apparatus for manufacturing nitrogen trifluoride includes a plurality of electrolytic cells, one rectifier is connected to each electrolytic cell and the same number of rectifiers as the number of electrolyzers has been used.

However, in this conventional manufacturing apparatus, as the number of electrolyzers increases, the power loss of the rectifier is accumulated, and there is a problem in that the manufacturing apparatus becomes large due to the use of a plurality of rectifiers.

The present invention is intended to reduce or solve the problems of the prior art, and it is possible to reduce the manufacturing cost by reducing the power loss in the DC power supply used in the nitrogen trifluoride manufacturing apparatus, and the manufacturing apparatus for nitrogen trifluoride having a simple structure as a whole aims to provide

The apparatus for producing nitrogen trifluoride according to an embodiment of the present invention includes a plurality of electrolytic cells in which an electrolysis reaction from ammonia (NH ₃ )-hydrogen fluoride (HF)-based molten salt to nitrogen trifluoride occurs, and AC power to DC power It characterized in that it comprises a DC power supply unit for supplying DC power to the plurality of electrolyzers by conversion.

According to an embodiment of the present invention, a plurality of electrolyzers of the apparatus for producing nitrogen trifluoride are connected in series to a DC power supply.

According to one embodiment of the present invention, the plurality of electrolyzers of the apparatus for producing nitrogen trifluoride are characterized in that there are two or more and five or less.

According to one embodiment of the present invention, the number of the plurality of electrolytic cells is characterized in that the output voltage of the DC power supply unit is determined to be less than 40V.

According to one embodiment of the present invention, the apparatus for producing nitrogen trifluoride is connected in common to a plurality of electrolytic cells and discharges an anode gas containing nitrogen trifluoride (NF ₃ ) from each electrolytic cell. And a plurality of It is commonly connected to the electrolytic cell of, from each electrolytic cell hydrogen (H ₂ ) It characterized in that it further comprises a cathode gas outlet for discharging a cathode gas containing.

According to the apparatus for manufacturing nitrogen trifluoride of the present invention, by supplying DC power to a plurality of electrolyzers by a single DC power supply unit, power loss in the DC power supply unit is reduced, and the manufacturing apparatus as a whole can be configured simply.

1 is a schematic structural diagram of an apparatus for producing nitrogen trifluoride according to an embodiment of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, with reference to drawings, preferable embodiment of this invention is described. However, the dimensions, materials, shapes and relative arrangements of the components of the manufacturing apparatus described below, or the processing flow of the manufacturing method, reaction conditions, etc. may be appropriately changed within the scope of the technical spirit of the present invention, It is not intended to limit the protection scope of the present invention to the embodiments described below.

As shown in FIG. 1, the apparatus for manufacturing nitrogen trifluoride according to an embodiment of the present invention includes a plurality of electrolytic cells 1 in which an electrolysis reaction of ammonia (NH ₃ )-hydrogen fluoride (HF)-based molten salt occurs. do. In FIG. 1, the apparatus for producing nitrogen trifluoride is illustrated as including two electrolytic cells, but the present invention is not limited thereto. .

The electrolyzer 1 is a reaction vessel in which the electrolysis of ammonia (NH ₃ )-hydrogen fluoride (HF)-based molten salt occurs, and separates an electrolyte solution and a product gas of the electrolysis reaction from the outside. The electrolytic cell 1 may have a cylindrical shape or a polygonal cylindrical shape (eg, a square cylindrical shape), and is usually made of a fluororesin, but may be made of a material such as a metal such as nickel if necessary.

In one embodiment of the present invention, as the electrolytic solution filled in the electrolytic cell 1 , ammonia (NH ₃ )-hydrogen fluoride (HF)-based molten salt is used. Such ammonia (NH ₃ )-hydrogen fluoride (HF)-based molten salt can also be prepared from ammonia (NH ₃ ) gas and anhydrous hydrogen fluoride (HF), and acidic ammonium fluoride (NH ₄ F·HF) and anhydrous hydrogen fluoride It can also be prepared from (HF), and can also be prepared from ammonium fluoride (NH ₄ F) and anhydrous hydrogen fluoride (HF).

For example, the electrolyte solution, in a separate preparation container or electrolyzer, a predetermined amount of ammonia (NH ₃ ) It can be prepared by directly reacting gas and hydrogen fluoride (HF) gas or liquid. Ammonia (NH ₃ ) When gas and hydrogen fluoride (HF) gas are reacted, if 10 to 90% by volume of dry inert gas, for example, nitrogen, argon, helium, etc. can be prepared.

As another preparation method, a predetermined amount of acid ammonium fluoride (NH ₄ F·HF) and/or ammonium fluoride (NH ₄ F) is added to a separate preparation container or electrolyzer, and a predetermined amount of anhydrous hydrogen fluoride (HF) gas is added thereto. can be blown to prepare an electrolyte.

As a composition of electrolyte solution, it is preferable that the molar ratio of hydrogen fluoride (HF)/ammonia (NH3) is _2-3.5 . An electrolytic solution having a molar ratio of less than 2 is undesirable because of its high viscosity. In addition, when the molar ratio exceeds 3.5, the vapor pressure of hydrogen fluoride (HF) increases, and the loss of hydrogen fluoride (HF) increases, which is not preferable because the composition of the electrolyte is fluctuated. The molar ratio of hydrogen fluoride (HF)/ammonia (NH ₃ ) is more preferably in the range of 2.4 to 3.2, and most preferably in the range of 2.5 to 3.0, from the viewpoint of stability of the composition.

The apparatus for producing nitrogen trifluoride according to an embodiment of the present invention further includes an anode 2 installed in the electrolytic cell 1 to cause an oxidation reaction and a cathode 3 to undergo a reduction reaction. As a result of the electrolysis reaction in the electrolytic cell 1, nitrogen trifluoride (NF3) is generated as an anode gas at the anode 2, and hydrogen (H ₂ ) is generated as a cathode gas at the cathode.

As the material of the anode 2, nickel and a metal having a high nickel content are used, and as the material of the anode 3, silver, stainless steel, nickel, and Monel may be used.

The electrolytic cell (1) is divided into an anode chamber and a cathode chamber by a partition wall (4) provided between the anode (2) and the cathode (3). The partition wall 4 is a separation means for preventing ignition/explosion by mixing nitrogen trifluoride (NF ₃ ) generated from the anode 2 and hydrogen (H ₂ ) generated from the cathode 3 . In order to more reliably separate nitrogen trifluoride (NF ₃ ) and hydrogen (H ₂ ), the lower end of the partition wall 4 is lower than the electrolyte level. The material of the partition wall 4 may be the same as that of the electrolytic cell 1, but is not limited thereto.

The apparatus for producing nitrogen trifluoride according to an embodiment of the present invention is to discharge nitrogen trifluoride (NF ₃ ) generated in the anode 2 and collected between the electrolyte surface and the upper surface of the anode chamber of the electrolyzer 1 to the outside. The anode gas discharge unit 5 and the cathode gas discharge unit 7 for discharging hydrogen (H ₂ ) generated at the cathode 2 and collected between the electrolyte surface and the upper surface of the cathode chamber of the electrolyzer 1 to the outside; include more

Although not shown in FIG. 1, in order to facilitate the discharge of the anode gas and the cathode gas to the outside, an inert gas such as nitrogen gas is fed as a carrier gas to the anode chamber side and the cathode chamber side of the electrolytic cell 1 can

The apparatus for producing nitrogen trifluoride according to an embodiment of the present invention further includes a DC power supply unit 10 for supplying DC power of a predetermined voltage to the electrolytic cell 1 . The DC power supply unit 10 may include an A/D converter or a rectifier that receives AC power of a predetermined voltage (eg, 200V to 400V), converts it into DC power of a predetermined voltage, and supplies the AC power. The DC power supply unit 10 may include, for example, a semiconductor rectifier or an A/D converter including the same, but the specific implementation thereof is not limited thereto.

It is preferable that the output of the DC power supply unit 10 is determined such that the electrolytic current density of the electrolytic cell 1 is 50 to 200A/dm ² . The lower limit of the current density is nitrogen trifluoride (NF ₃ ) Since it directly affects the productivity of the gas, it is determined in consideration of the productivity of the manufacturing apparatus. The upper limit of the current density is set so that the temperature of the electrolyte does not affect the composition of the electrolyte. That is, since the heat generated in the vicinity of the electrode is almost proportional to the current density, if the current density becomes too high, the temperature of the electrolytic solution becomes locally high, resulting in problems such as not being stable in composition. From this point of view, the range of current density is preferably 50-200A/dm ² , and more preferably 60-150A/dm ² .

The apparatus for producing nitrogen trifluoride according to an embodiment of the present invention is characterized in that a DC power supply for electrolysis is supplied to the plurality of electrolyzers 1a and 1b by a single DC power supply unit 10 .

For example, in the embodiment shown in FIG. 1 , one DC power supply unit 10 supplies DC power to two electrolytic cells 1a and 1b connected in series. That is, the positive terminal of the DC power supply unit 10 is connected to the positive electrode 2b of the second electrolyzer 1b, and the negative terminal of the DC power supply unit 10 is connected to the negative electrode 3a of the first electrolytic bath 1a, The anode 2a of the first electrolytic cell 1a is connected to the cathode 3b of the second electrolytic cell 1b. Even when there are three or more electrolyzers 1, the electrolytic cells are connected in series in the same way, and DC power can be supplied from one DC power supply unit 10 thereto.

The number of the electrolyzer 1 connected in series to the DC power supply unit 10 is preferably 2 or more and 5 or less. When there are more than 6 units, the output voltage of the DC power supply unit 10 increases (eg, about 50 V or more), which is not preferable because there is a risk of electric shock, and the effect of reducing power loss is also not large. From the viewpoint of reducing power loss and reducing the risk of electric shock, the number of electrolyzers 1 connected in series to one DC power supply unit 10 is preferably 2 to 5 units, more preferably 2 units or 3 units. . In particular, the number of electrolytic cells 1 connected in series to one DC power supply unit 10 is preferably adjusted so that the output voltage of the DC power supply unit 10 is 40V or less in order to reduce the risk of electric shock.

When there are a plurality of electrolytic cells 1, as shown in FIG. 1, by providing each of the anode gas discharge unit 5 and the cathode gas discharge unit 7 in common to the plurality of electrolytic cells 1a and 1b, the manufacturing apparatus It is preferable because it can be made simple. That is, the anode gas discharge unit 5 collects the anode gas from the first electrolytic cell 1a, that is, nitrogen trifluoride (NF ₃ ) and the anode gas from the second electrolytic cell 1b, and discharges it to the outside at once. it is preferable Similarly, the cathode gas discharge unit 7 is also configured to collect the cathode gas from the first electrolytic cell 1a, that is, hydrogen (H ₂ ) and the cathode gas from the second electrolytic cell 1b, and discharge it to the outside at once. desirable.

The manufacturing apparatus shown in FIG. 1 is exemplary, and the shape of the electrolytic cell 1 of the present invention, the arrangement of the anode 2 and the cathode 3, and the arrangement and length of the partition wall 4 are shown in FIG. It is not limited thereto, and may have various structures, arrangements, and dimensions. In addition, the connection structure of the DC power supply unit 10 and the plurality of electrolytic cells 1 is also not limited to that shown in FIG. 1 , and may have other connections. Although not shown in FIG. 1 , the nitrogen trifluoride manufacturing apparatus may further include a supply pipe of a raw material for preparing an electrolyte solution.

Nitrogen trifluoride (NF ₃ ) by a one-step reaction method using the nitrogen trifluoride production apparatus of the present invention The outline of the gas production process is as follows.

First, as the electrolyte, NH ₃ -HF molten salt composed of ammonia (NH ₃ ), ammonium fluoride, acid ammonium fluoride (NH ₄ F·HF), and anhydrous hydrogen fluoride (HF) is used. This is electrolyzed in the anode 2 made of nickel in the electrolytic cell 1 . Nitrogen trifluoride (NF ₃ ) Gas is generated at the anode, crude nitrogen trifluoride (NF ₃ ) with nitrogen as the main impurity gas can be obtained. Through a simple purification process, crude nitrogen trifluoride (NF ₃ ) gas can be high-purity nitrogen trifluoride (NF ₃ ) having a purity of 99.999% by volume or more.

Hereinafter, an embodiment according to the number of the electrolytic cell 1 will be described.

Example 1

In Example 1 of the present invention, an AC power of 400V was input to the DC power supply unit 10 , and DC power output from the DC power supply unit 10 was supplied to two electrolyzers connected in series. At this time, the output current from the DC power supply unit 10 was set to 8000A. This corresponds to an electrolytic current density of 80A/dm ² , and the output voltage of the DC power supply unit 10 was 16.2V.

In the configuration of the manufacturing apparatus according to Example 1 of the present invention, the power efficiency of the DC power supply unit 10 was 90.1%.

Example 2

Embodiment 2 of the present invention is different from Embodiment 1 in that three electrolyzers are connected in series to one DC power supply unit 10 .

That is, in Example 2, an AC power of 400 V was input to the DC power supply unit 10, and the DC power output from the DC power supply unit 10 was supplied to three electrolytic cells connected in series. At this time, the output current from the DC power supply unit 10 was set to be 8000A as in the first embodiment. Therefore, the electrolysis current density in Example 2 also corresponded to 80 A/dm ² similarly to Example 1, and the output voltage of the DC power supply part 10 was 24.3V.

In the configuration of the manufacturing apparatus according to the second embodiment of the present invention, the power efficiency of the DC power supply unit 10 was 92.5%.

Comparative Example 1

In the comparative example, 400V AC power was input to one DC power supply unit 10 , and DC power output from the DC power supply unit 10 was supplied to one electrolyzer. The output current from the DC power supply unit 10 was set to 8000A as in Examples 1 and 2. Accordingly, the electrolysis current density in the comparative example is also equivalent to 80 A/dm ² as in Example 1 (that is, the same amount of nitrogen trifluoride as in Example 1 can be obtained), and the output voltage of the DC power supply unit 10 is It was 8.1V.

In the configuration of the manufacturing apparatus according to this comparative example, the power efficiency of the DC power supply unit 10 was 81.7%.

As such, according to the present invention, by connecting a plurality of electrolyzers 1 to one DC power supply unit 10, power loss in the DC power supply unit 10 can be reduced by 10% or more compared to the prior art, and the entire manufacturing apparatus The structure can be simplified.

1, 1a, 1b: electrolytic cell
2, 2a, 2b: positive pole
3, 3a, 3b: cathode
4, 4a, 4b: bulkhead
5: Anode gas outlet
7: Cathode gas discharge part
10: DC power supply unit
11: AC power supply

Claims (5)

As an apparatus for producing nitrogen trifluoride,
A plurality of electrolytic cells in which an electrolysis reaction of ammonia (NH ₃ )-hydrogen fluoride (HF)-based molten salt to nitrogen trifluoride occurs, and
An apparatus for producing nitrogen trifluoride, comprising a DC power supply unit for converting AC power into DC power and supplying DC power to the plurality of electrolyzers. According to claim 1,
The plurality of electrolyzers are apparatus for producing nitrogen trifluoride, characterized in that connected in series to the DC power supply. 3. The method of claim 2,
The plurality of electrolytic cells are two or more and five or less units of nitrogen trifluoride manufacturing apparatus, characterized in that. 4. The method of claim 3,
The number of the plurality of electrolyzers, the apparatus for producing nitrogen trifluoride, characterized in that the output voltage of the DC power supply is determined to be less than 40V. 3. The method of claim 2,
An anode gas discharge unit commonly connected to the plurality of electrolytic cells to discharge an anode gas containing nitrogen trifluoride (NF ₃ ) from each electrolytic cell;
A cathode gas discharge unit commonly connected to the plurality of electrolytic cells to discharge cathode gas containing hydrogen (H ₂ ) from each electrolytic cell
The apparatus for producing nitrogen trifluoride, characterized in that it further comprises.

Images