KR100712345B1 - Apparatus for generating f2 gas and method for generating f2 gas? and f2 gas - Google Patents

Abstract

The present invention is a F ₂ gas generator (G) for generating high-purity F ₂ gas by electrolyzing an electrolytic bath (24) consisting of KF 2HF, a preparation system prepared from KF or KF · HF to KF · 2HF ( A), an HF supply system (B) for supplying HF to the electrolytic bath (24) and the preparation system (A), and KF 2HF prepared by the preparation system (A) were electrolyzed to F ₂ gas. It characterized in that it comprises a F ₂ gas generator (C) for generating a.

Description

F2 gas generator, F2 gas generating method and F2 gas {APPARATUS FOR GENERATING F2 GAS AND METHOD FOR GENERATING F2 GAS 、 AND F2 GAS}

The present invention relates to an F ₂ gas generator, an F ₂ gas generating method, and an F ₂ gas. In particular, to a F ₂ gas obtained by the production process F ₂ gas generating apparatus for the generation of a very small impurity of high purity F ₂ gas used for, F ₂ gas generating method and those of a semiconductor.

F ₂ gas is used as, for example, a term gas which is indispensable in the semiconductor manufacturing field. In addition, although it may be used by itself, recently, nitrogen trifluoride gas (hereinafter, referred to as NF ₃ gas) or the like is synthesized based on the F ₂ gas, and used as a cleaning gas or dry etching gas for semiconductors. Doing. Neon fluoride gas (hereinafter referred to as NeF gas), argon fluoride gas (hereinafter referred to as ArF gas), krypton fluoride gas (hereinafter referred to as KrF gas), and the like are used in the excimer laser for patterning of semiconductor integrated circuits. an oscillator for a gas, the raw material is widely used a mixed gas of rare gas and F ₂ gas.

The F ₂ gas is generated by electrolysis using carbon as an anode and nickel as a cathode in an electrolytic cell containing a bath of a predetermined amount of KF · HF. In general, KF · HF housed in an electrolytic cell is initially used as a KF · 2HF by supplying a predetermined amount of KF · HF and then supplying HF appropriately. At this time, a predetermined amount of bath is prepared by adding a shortage of KF · HF as KF · 2HF and supplying HF again.

KF, which is a component of the bath, has high hygroscopicity and generally contains water in the dry bath. We first applied for a high-purity fluorine generating device with few impurities (WO 01 / 77412Al).

However, the F ₂ gas generated in this way contains 45 to 55% of oxygen in the F ₂ gas generated initially. The generated F ₂ gas and the water contained in the electrolytic bath generally reduce the amount of oxygen contained in the F ₂ gas by the reaction shown in Scheme 1. However, it is difficult to make the amount 3000 ppm or less.

The surface treatment of the above-mentioned excimer laser oscillation gas and the stepper lens (CaF ₂ single crystal) of the excimer laser requires a high purity F ₂ gas. The oxygen concentration contained in the F ₂ gas is required to be 1000 ppm or less for the former excimer laser oscillation gas and 500 ppm or less for the surface treatment gas of the stepper lens (CaF ₂ single crystal) of the latter excimer laser.

The present invention, the oxygen content is very low, and an object thereof is to provide an F ₂ gas which can kill the event of a high purity F ₂ gas at a stable generator, F ₂ gas generation method and a high purity F ₂ gas.

F ₂ gas generating apparatus of the present invention for solving the foregoing problems is KF · by electrolyzing an electrolytic bath consisting of 2HF according to F ₂ gas generating device that generates the F ₂ gas of high purity, KF or KF · HF to KF · A preparation system prepared with 2HF, an HF supply system for supplying HF to the electrolytic bath and the preparation system, and an F ₂ gas generated by electrolysis of KF 2HF prepared by the preparation system. _It is characterized by including ₂ gas generating systems.

After preparing in a closed system from KF or KF · HF to KF · 2HF, the prepared KF · 2HF is introduced into an electrolytic cell hermetically connected to the preparation system. For this reason, KF.2HF injected into the electrolytic cell can absorb water, that is, it can be set as an electrolytic bath with a low oxygen content. Thus, it is possible to the amount of oxygen contained in the F ₂ gas is obtained by electrolysis of the electrolytic bath to be very low from the initial stage of generation.

In addition, the F ₂ gas generator of the present invention is characterized in that the preparation system is provided with water removing means for removing water in the KF or KF.HF.

Oxygen amount can be reliably reduced at the time of preparation from KF or KF * HF to KF * 2HF.

In addition, the F ₂ gas generator of the present invention has an oxygen concentration of 2% or less in the generated F ₂ gas.

The oxygen concentration in the F ₂ gas is 2% or less, preferably 0.2% or less (2000 ppm or less), and more preferably 0.02% or less (200 ppm or less). For this reason, it can be used as an excimer laser oscillation gas and the surface treatment gas of an excimer laser stepper lens (CaF ₂ single crystal).

Further, F ₂ gas generating device of the present invention, KF · preparation to by electrolyzing an electrolytic bath consisting of 2HF according to F ₂ gas generating device for generating an F ₂ gas, to prepare a KF · 2HF from KF or KF · HF-based And an HF supply system for supplying HF to the electrolytic bath and the preparation system, and an F ₂ gas generator for generating F ₂ gas by electrolysis of KF · 2HF prepared by the preparation system. It is characterized in that the water control means for adjusting the water in the external atmosphere of each of the preparation system, the HF supply system and the F ₂ gas generating system or the whole system is provided.

Moisture control means for adjusting the water in the external atmosphere of the preparation system, the HF supply system, and the F ₂ gas generator system or the entire system is provided, whereby the mixing of oxygen can be reliably suppressed.

Further, in the F ₂ gas generator of the present invention, the moisture control means is a housing, and the housing makes it possible to control the atmosphere inside the compartment or the whole compartment.

Since the moisture control means is a housing capable of controlling the atmosphere, it is possible to easily adjust the atmospheric humidity of each system or the whole system. Thereby, mixing of oxygen can be suppressed reliably.

Further, F ₂ way gas generated in the present invention is a water removal means according to F ₂ gas generating method of KF · by electrolyzing an electrolytic bath consisting of 2HF generate the F ₂ gas, to remove moisture in the KF or KF · HF In the preparation system for preparing KF or KF · HF laid in KF · 2HF, the KF or KF · HF is heated and degassed in a vacuum or inert gas atmosphere for a predetermined time, and then cooled to room temperature in a vacuum or inert gas atmosphere. Subsequently, HF vaporized from the HF supply system was supplied into the preparation system, and the KF or KF HF and the HF were reacted in the preparation system to generate KF 2HF, and the KF 2HF was generated by F ₂ gas. After supplying to the electrolytic cell of the system, it is electrolyzed to generate F ₂ gas of low oxygen concentration.

With such a configuration, it is possible to reduce the oxygen concentration in the generated F ₂ gas and to use the gas for surface treatment of the excimer laser oscillation gas or the stepper lens (CaF ₂ single crystal) of the excimer laser.

In addition, the F ₂ gas generating method of the present invention is to heat the KF or KF · HF at 200 ~ 300 ℃ in the preparation system, to remove the adsorption water and crystal water of the KF or KF.HF.

In this way, water in KF or KF.HF can be removed reliably. By this, it is possible to certainly reduced since it is possible to remove oxygen, the steps of the F ₂ gas oxygen concentration F ₂ gas is generated during the initial generated which is contained in the water.

Further, the F ₂ gas of the present invention is prepared in the preparation system for preparing KF or KF · HF with KF · 2HF in which water removal means for removing water in KF or KF · HF is provided. After heating and degassing in a vacuum or inert gas atmosphere for a predetermined time, cooling to room temperature in a vacuum or inert gas atmosphere, and then supplying HF vaporized from an HF supply system into the preparation system, and the KF or KF · HF reacts with the HF to generate KF · 2HF, and the KF · 2HF is supplied to an electrolytic cell of an F ₂ gas generator, followed by electrolysis. Therefore, since the oxygen concentration is very high purity F ₂ gas, it can be used as various periodic gases for semiconductor manufacturing.

In addition, the F ₂ gas of the present invention has an oxygen concentration of 2% or less.

The oxygen concentration in the F ₂ gas is preferably reduced to 0.2% or less (2000 ppm or less), more preferably 0.02% or less (200 ppm or less). For this reason, it can be used as gas for surface treatment of an excimer laser oscillation gas, or the stepper lens (CaF ₂ single crystal) of an excimer laser.

1 is a schematic view of the fluorine gas generator of the present invention,                 

FIG. 2 is a diagram showing the relationship between the energization amount in the case of Example 1 and Comparative Examples 1 and 3 and the amount of O ₂ in the F ₂ gas.

Hereinafter, an example of embodiment of this invention is described based on FIG.

The F ₂ gas generator G according to the present embodiment generates high-purity F ₂ gas by electrolyzing an electrolytic bath 24 made of KF 2HF. The F ₂ gas generating device G prepares KF or KF HF by KF 2HF. F ₂ gas by electrolysis of the preparation system (A), the HF supply system (B) for supplying HF to the electrolytic bath (24) and the preparation system (A), and the KF 2HF prepared by the preparation system (A). It is configured with a F ₂ gas generator (C) for generating a.

In FIG. 1, the preparation system A prepared from KF or KF * HF to KF * 2HF is the container 7a made from Ni which accommodates the KF10, and the top cover which seals the said container 7a ( A heater 9 for covering the container 7a of the KF · 2HF preparation device 7 and heating the KF 10 therein; The HF supply is inserted into the cooling water pipe (8), the vacuum pipe (2) connected to the vacuum exhaust machine (D) installed on the upper cover (7b), the inert gas purge pipe (3), and the KF (10). It consists of an HF supply and KF / 2HF delivery piping (1) connected to the system (B) and the F ₂ gas generator (C).

In the HF supply system B for supplying HF to the preparation system A, an HF cylinder 11 disposed on the load cell 12 is provided in the caster 13. The caster 13 is connected to an acryl scubar (not shown). The surface of the HF cylinder 11 is covered with the heater 14, and the inside of the HF cylinder 11 is kept at a predetermined temperature. Further, the HF supply to the HF gas cylinder 11 is measured, and based preparation (A) and the amount of gas in the F ₂ gas generating system (C) by a load cell 12 is measured. The HF cylinder 11 is connected to the preparation system A by the HF delivery pipe 5.

The F ₂ gas generating system (C) includes an electrolytic bath (24) made of KF · 2HF mixed molten salt, an electrolytic cell (20) for accommodating the electrolytic bath (24), and an anode for electrolyzing the electrolytic bath (24). The main components are composed of the 22 and the cathode 23.

The electrolytic cell 20 is formed integrally with a metal such as Ni, Monel, pure iron, stainless steel, or the like. The electrolytic cell 20 is separated into the anode chamber 28 and the cathode chamber 29 by partition walls 27 made of Ni or Monel. An anode 22 made of low polarity carbon is disposed in the anode chamber 28, and a cathode 23 made of Ni or Fe is disposed in the cathode chamber 29. The top cover 30 of the electrolytic cell 20 has an F ₂ gas outlet 25 generated from the anode chamber 28 and the cathode chamber 29, and an H ₂ gas outlet 26 generated from the cathode chamber 29. Is installed. In addition, the electrolytic cell 20 is provided with a heater 31 for heating the inside of the electrolytic cell 20. In addition, although not shown in the periphery of the heater 31, a heat insulating material is provided. The heater 31 is not particularly limited in form, such as a ribbon type or nichrome wire, but is preferably in a shape covering the entire circumference of the electrolytic cell 20.

The vacuum exhaust machine (D) is composed of a molecular sieve 16 and a vacuum pump (17). And when KF10 accommodated in the preparation system A is heated by the heater 9, the water | moisture content which desorbs from KF10 is sucked in. Water removal means in the present invention comprises a heater (9) and a vacuum exhaust machine (D). The operation principle of the water removal means will be described later.

Next, a description will be given of the operation of the F ₂ gas generator (G) that are configured as described above.

After heat-processing the preparation system A previously by the heater 9 at 250-300 degreeC, the predetermined amount of KF10 is loaded in the container 7a. Then, the mixture is heated to 250 to 300 ° C. again under vacuum or purge of an ultra high purity inert gas, and maintained for 24 to 48 hours to dry KF 10. At this time, the vacuum piping valve 2a is opened, the valve 3a and the valve 4b are closed, and the inside of the container 7b is exhausted by the vacuum exhaust machine D. As shown in FIG. In this way, the KF 10 can be desorbed in the KF 10 by being heated again to 250 to 300 ° C. under heat purge for 24 to 48 hours under a purge of an ultra high purity inert gas.

Thermogravimetry of KF (hereinafter referred to as TG) and differential thermal analysis (hereinafter referred to as DTA) showed endothermic peaks of 43.4 ° C, 64.4 ° C, 90.8 ° C and 151.6 ° C. Among these, the endothermic peaks at 43.4 ° C, 64.4 ° C, and 90.8 ° C are adsorption water, and the peak at 151.6 ° C is due to desorption of crystal water. The adsorbed water of KF serving as a raw material is considered to be easily decomposed by the reaction represented by Scheme 1 described above. However, the crystal water corresponding to the endothermic peak at 151.6 ° C. of the DTA has a strong interaction with KF, and HF mainly contained in the electrolytic bath forms a network by hydrogen bonding. It is thought to be difficult to spread and difficult to exclude. Therefore, as described above, the KF is heated again to 250 to 300 ° C. under a purge of an ultra high purity inert gas and heat-treated for 24 to 48 hours, preferably 10 to 30 hours, whereby the crystal water can be desorbed.

Then, it cools to room temperature, closes the valve 2a, and opens the valve 4b and the valve 3a. At this time, the line heater 15 preheats the piping 4 for high purity inert gas to 30-35 degreeC previously. The HF cylinder 11 is heated by the heater 14 to gasify the HF, and when the valve 5 is opened, HF is gradually introduced into the KF 10 of the preparation system A. At this time, the reaction between the KF 10 and HF is intense and generates heat, so that water flows into the cooling water pipe 8 to cool the KF 2HF preparation device 7 to prevent the temperature from becoming 100 ° C or higher. This is because when the temperature exceeds 100 ° C. and reaches 200 ° C., a sudden sudden rise of HF occurs, which is similar to an explosion.

In this way, when HF is introduced into the preparation system A and the HF to the KF 10 is higher than the molar ratio of KF and HF, the supply speed of HF can be increased. Then, after confirming that the predetermined amount of HF is supplied to the preparation system A by the load cell 12 of the HF supply system B, the valve 5a is closed and the valve 4a is opened and high purity is obtained. Inert gas is introduced from the pipe 1 and exhausted from the inert gas purge pipe 3. This is because the HF in the pipe 1 is rapidly absorbed by KF 2HF in which the KF 10 is prepared by KF 2HF, thereby preventing the backflow solidification of the KF 2HF into the pipe 1.

After the purge system A is purged with an inert gas for a suitable time, the valve 4b is closed. Next, an inert gas is supplied from the inert gas purge piping 3. At the same time, the valve 18 and the valve 19 are opened. The preparation system A sends the prepared KF.2HF from the piping 1 into the electrolytic cell 20 of the F ₂ gas generating system C by the gas pressure of the inert gas introduced from the inert gas purge piping 3. do. At this time, the electrolytic cell 20 is heat-treated at 250-300 degreeC in advance, and desorbed water etc. are desorbed.

As described above, in the F ₂ gas generator according to the present invention, high-purity KF 2HF having a small amount of water adsorption can be supplied into the electrolytic cell of the F ₂ gas generator, and the high-purity electrolytic bath KF 2HF can be supplied in the electrolytic cell. You can swear insults. As a result, the oxygen concentration of the electrolytic bath is greatly reduced.

In addition, each system of the preparation system A, the HF supply system B, and the F ₂ gas generating system C may be housed in a housing capable of controlling the atmosphere. Thereby, the humidity of the external atmosphere of each system can be adjusted, and the oxygen mixed in each system can be suppressed. Further, the total angle meter, that can be stored in the F ₂ gas generator (G) in a single housing. Moreover, by providing these whole systems in a clean room, the effect similar to storing in the housing | casing which can control atmosphere can also be acquired. In this way, it is possible to reduce the oxygen concentration in the F ₂ gas generated more reliably by suppressing the incorporation of oxygen into each system.

In addition, the F ₂ gas generator and the F ₂ gas generator according to the present invention are not limited to the above-described embodiment.

(Example)

Hereinafter, the F ₂ gas generator according to the present invention will be described in detail by way of examples.

(Example 1)

In the F ₂ gas generator G shown in FIG. 1, the preparation system A is heat-treated at 250 to 300 ° C. by the heater 9 in advance, and the container 7a is loaded with KF 10. Under the purge of high purity N ₂ gas having a purity of 99.9999%, the mixture was heated to 250 ° C to 300 ° C and held for 24 to 48 hours to dry KF (10). Thereafter, the mixture was cooled to room temperature and HF was introduced into KF (10) of the preparation system (A). At this time, water was flowed into the cooling water pipe 8 to cool the KF 2HF preparation device 7 so that the temperature was 100 ° C or lower. Then, after confirming that the predetermined amount of HF is supplied to the preparation system A by the load cell 12 of the HF supply system B, after purging the preparation system A with high purity N ₂ gas for a suitable time, high purity The N ₂ gas was supplied, and the prepared KF · 2HF was sent from the pipe 1 into the electrolytic cell 20 of the F ₂ gas generator C, and the electrolytic bath of the bath amount 71 was bathed. . In the F ₂ gas generator C, constant current electrolysis was performed at an applied current density of 10 A / dm 2 using a carbon electrode at the anode and a Ni electrode at the cathode. The amount of O ₂ in the F ₂ gas generated by gas chromatography at the time of about 100 Ahr of energization was measured and found to be about 650 ppm.

(Example 2)

Constant current electrolysis was performed at an applied current density of 15 A / dm ₂ using the same KF · 2HF as Example 1 as the electrolytic bath, using a carbon electrode at the anode and a Ni electrode at the cathode in the F ₂ gas generator C. did. Then, the measurement of the O ₂ content in the F ₂ gas generated by the gas chromatography on the distribution amount of about 100Ahr time bar was about 450ppm.

(Example 3)

Using the same KF · 2HF as in Example 1 as the electrolytic bath, constant current electrolysis was performed at an applied current density of 2 A / dm 2 using a carbon electrode at the anode and a Ni electrode at the cathode in the F ₂ gas generating system (C). . Then, the measurement of the O ₂ content in the F ₂ gas generated by the gas chromatography on the distribution amount of about 100Ahr time bar was about 950ppm.

(Example 4)

The same KF 2HF as in Example 1 is used as an electrolytic bath, and the F ₂ gas generator C is housed in a housing (not shown) which is a moisture control means, the humidity inside the housing is controlled to 40%, and the carbon electrode is mounted on the anode. Using the Ni electrode as the cathode, constant current electrolysis was performed at an applied current density of 20 A / dm 2. At the time of about 100 Ahr, the amount of O ₂ in the F ₂ gas generated by gas chromatography was measured, and it was about 70 ppm.

(Comparative Example 1)

Using KF · 2HF adjusted by the conventional method as the electrolytic bath, and using a carbon electrode at the anode and a Ni electrode at the cathode in the F ₂ gas generator C, constant current electrolysis is performed at an applied current density of 10 A / dm 2. Carried out. And, by gas chromatography in the distribution amount of about 100Ahr point, F ₂ occurred was about 30000ppm of measuring the O ₂ content in the gas bar.

(Comparative Example 2)

Constant current electrolysis is performed at an applied current density of 15 A / dm ₂ using KF · 2HF adjusted by a conventional method as an electrolytic bath and using a carbon electrode at the anode and a Ni electrode at the cathode in the F ₂ gas generator C. did. The amount of O ₂ in the F ₂ gas generated by gas chromatography at the time of about 100 Ahr of energization was about 25000 ppm.

(Comparative Example 3)

Constant current electrolysis was performed at an applied current density of 1 A / dm ₂ using the same KF · 2HF as in Example 1 as the electrolytic bath, using a carbon electrode at the anode and a Ni electrode at the cathode in the F ₂ gas generator C. . The amount of O ₂ in the F ₂ gas generated by gas chromatography at the time of about 100 Ahr of energization was measured and found to be about 21000 ppm.

2 shows the relationship between the amount of electricity supplied in Examples 1 and Comparative Examples 1 and 3 and the amount of O ₂ in the F ₂ gas.

2, and then dried to KF desorption of moisture, KF · It of Example 1 Electrolytic that is adjusted to a 2HF with the bath can be seen that with low oxygen content in the F ₂ gas from the F ₂ gas generating initial have.

The present invention is constructed as described above, and after the KF is dried and the surface adsorbed water or the crystal water is desorbed, KF 2HF is used to stabilize the F ₂ gas having a very low oxygen concentration from the beginning of F ₂ gas generation. It is possible to generate it.

Claims (9)

In the F ₂ gas generator which generates an F ₂ gas by electrolyzing an electrolytic bath composed of KF 2HF, Preparation system for preparing KF or KF and HF with KF and 2HF, An HF supply system for supplying HF to the electrolytic bath and the preparation system, and F ₂ gas generating apparatus comprising an F ₂ gas-generating system for the electrolyzing a KF · 2HF prepared by the preparation system generates an F ₂ gas. The method of claim 1, The preparation system, the F ₂ gas generating apparatus characterized in that the moisture removal means for removing moisture in the KF or KF · HF is laid. The method of claim 1, The F ₂ gas generator, characterized in that the oxygen concentration in the generated F ₂ gas is 2% or less. In the F ₂ gas generator that generates an F ₂ gas by electrolyzing an electrolytic bath composed of KF 2HF, Preparation system prepared from KF or KF · HF to KF · 2HF, An HF supply system for supplying HF to the electrolytic bath and the preparation system, and And a F ₂ gas generator that generates F ₂ gas by electrolyzing KF · 2HF prepared by the preparation system, The preparation system, HF supply system F and F ₂ gas generating device, characterized in that the moisture control means are installed to adjust the water content in each type or each of the total external atmosphere from various fields of the _second gas generating system. The method of claim 4, wherein The moisture control means and the housing, the housing F ₂ gas generating device, characterized in that for performing the control of the internal atmosphere for storing the total of the various fields, or from various fields. In the F ₂ gas generating method of KF · by electrolyzing an electrolytic bath consisting of 2HF generate the F ₂ gas, In a preparation system for preparing KF or KF · HF with KF · 2HF, which is provided with water removal means for removing water in KF or KF · HF, the KF or KF · HF may be used for 24 to 48 hours in a vacuum or inert gas atmosphere. After heating and degassing at 200 to 300 ° C. under a vacuum or an inert gas atmosphere, it is cooled to room temperature, and then HF vaporized from an HF supply system is supplied into the preparation system, and the KF or KF. HF reacts with the HF to generate KF · 2HF, and supplies the KF · 2HF to an electrolytic cell of an F ₂ gas generator, followed by electrolysis to generate an F ₂ gas having an oxygen concentration of 2% or less. F ₂ gas generation method. delete In the preparation system which prepares KF or KF and HF by KF and 2HF in which the water removal means which removes water in KF or KF and HF is provided, The KF or KF · HF is heated and degassed at 200 to 300 ° C. under a vacuum or inert gas atmosphere for 24 to 48 hours, and then cooled to room temperature in a vacuum or inert gas atmosphere, and then gaseous from the HF supply system in the preparation system. HF was fed to react the KF or KF.HF with the HF in the preparation system to generate KF.2HF. The KF.2HF was supplied to an electrolytic cell of an F ₂ gas generator. F ₂ gas, characterized in that. The method of claim 8, F ₂ gas, characterized in that the oxygen concentration is 2% or less.

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