JP2009221542A - Fluorine gas generating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorine gas generating apparatus in which the life of a seal member used in a pressurizer and comprising a synthetic resin is prolonged. <P>SOLUTION: The fluorine gas generating apparatus 1000 has an electrolytic cell 1 in which an electrolyte 2 comprising a mixed molten salt containing hydrogen fluoride is formed, adsorption means 14, 15 for adsorbing hydrogen fluoride in a fluorine-containing gas produced by the electrolysis of the electrolyte 2 and discharged from the electrolytic cell 1, the pressurizer 21 for pressurizing the fluorine gas in the fluorine-containing gas having the adsorbed hydrogen fluoride and a casing 100 housing the electrolytic cell 1, the adsorption means 14, 15 and the pressurizer 21. The pressurizer 21 uses the synthetic resin made seal member for insulating the inside of the pressurizer from the outside of the pressurizer to keep the purity of a gas passing through the pressurizer 21. The pressurizer 21, the electrolytic cell 1 and the adsorption means 14, 15 are each divide by partition wall in the casing 100. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fluorine gas generator, and more particularly to a fluorine gas generator that generates fluorine gas used in manufacturing processes of semiconductors and the like.

Conventionally, fluorine gas is an essential gas that is indispensable in the field of semiconductor manufacturing, for example. In some cases, nitrogen trifluoride gas (hereinafter referred to as NF ₃ gas) is synthesized based on fluorine gas, and this is used as a semiconductor cleaning gas or dry etching gas. The demand for these products is growing rapidly. Further, 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 during patterning of a semiconductor integrated circuit. The excimer laser oscillation gas used is a mixed gas of rare gas and fluorine gas.

  As such a fluorine gas generator, the one shown in Patent Document 1 below is already known.

JP 2004-107761 A

  When synthetic resin is used as a seal member of a pressurizer (compressor) in the fluorine gas generator of Patent Document 1, depending on the positional relationship, an HF adsorption tower operated at about 100 ° C., or about 80 ° C. to about 80 ° C. When heat is transferred from an electrolytic cell that is kept at 100 ° C. and operated, the synthetic resin may deteriorate early, and the synthetic resin or pressurizer itself must be replaced early. was there.

  As a countermeasure, it may be possible to install the pressurizer away from the HF adsorption tower or the electrolytic cell. However, in recent years, the fluorine gas generator is required to be downsized. Needless to say, the pressurizer cannot be sufficiently separated from the adsorption tower or the electrolytic cell.

  The present invention has been made to solve the above problems, and even if it is small, the fluorine gas generator can extend the life of a sealing member made of a synthetic resin used in a pressurizer. The purpose is to provide.

  In the present invention, an electrolytic bath in which an electrolytic bath made of a mixed molten salt containing hydrogen fluoride is formed, and a fluorine-containing gas containing fluorine gas generated by electrolyzing the electrolytic bath is discharged from the electrolytic bath, An adsorbing means for adsorbing hydrogen fluoride contained in the fluorine-containing gas, a pressurizer for pressurizing the fluorine gas of the fluorine-containing gas adsorbed with hydrogen fluoride, the electrolytic cell, and the adsorbing means, A fluorine gas generator comprising a housing in which the pressurizer is accommodated, wherein the pressurizer maintains the purity of the gas passing through the pressurizer and the interior of the pressurizer. And a seal member made of synthetic resin for blocking the outside of the pressurizer, and the pressurizer, the electrolytic cell, and the adsorption means are partitioned by a partition in the housing. ing. The synthetic resin is preferably a fluororesin containing 40 to 75% fluorine. Here, as a synthetic resin, for example, polymers such as PCTFE (polytrifluoride ethylene), PVDF (polyvinylidene fluoride), PVF (polyvinyl fluoride), VF2 (vinylidene fluoride), HFP (hexafluoropolypropylene) , TFE (tetrafluoroethylene), PMVE (perfluoromethyl vinyl ether), and other such copolymers using a copolymer (for example, Viton (registered trademark) composition) can be used.

  According to the present invention, even if the HF adsorption tower and the electrolytic cell, which are main heat sources in the fluorine generator, and the pressurizer are installed in the same casing, It is possible to provide a fluorine gas generator capable of extending the life of a sealing member made of synthetic resin. In addition, if a fluororesin does not contain 40% or more of fluorine, it will be inferior to corrosion resistance in order to use as a sealing member of a pressurizer. On the other hand, a resin containing an amount exceeding 75% of fluorine is inferior in flexibility and inferior in sealing properties. For example, Viton (registered trademark) contains about 55% of fluorine, and this amount of fluorine can be sufficiently used for a seal member of a pressurizer. Teflon (registered trademark) contains about 76% fluorine, and is easily inferior to sealing when used as a seal member for a pressurizer.

  Hereinafter, a fluorine gas generator according to an embodiment of the present invention will be described. FIG. 1 is a schematic view of a main part of a fluorine gas generator according to an embodiment of the present invention. FIG. 2 is a schematic diagram for explaining an arrangement configuration of main parts of the fluorine gas generator of FIG.

  In FIG. 1, a portion 100 partitioned by a one-dot chain line is a casing. As shown in FIG. 2, the interior of the housing 100 is partitioned into a first partition 101, a second partition 102, and a third partition 103. This partitioning is performed by partition walls 104, 105, and 106 made of a heat insulating material or the like. Due to the partitioning action of the partition walls 104, 105, 106, heat conduction between the partitions is suppressed. In FIG. 1, a portion 101 partitioned by a broken line is a first partition and a portion 102 is a second partition, but the third partition 103 is not shown for convenience.

  As shown in FIG. 1, an electrolytic cell 1, a hot water heating device 12, HF adsorption towers (adsorption means) 14 and 15, and a buffer tank 20 are accommodated in the first section 101.

  As shown in FIG. 1, a compressor (pressurizer) 21 is accommodated in the second section 102. As shown in FIG. 2, the second compartment 102 also stores an integrated gas system (IGS (registered trademark)) 31 (not shown in FIG. 1).

  As shown in FIG. 2, the electric control unit 32 is accommodated in the third section 103.

  An electrolytic bath 2 made of a KF-HF mixed molten salt is formed in the electrolytic cell 1. The electrolytic cell 1 is made of a metal or alloy such as Ni, Monel, pure iron, stainless steel, or the like, and an anode chamber 3 and an anode chamber located at the center of the electrolytic cell 1 by a skirt-shaped partition wall 16 made of Ni or Monel. 3 is separated into a cathode chamber 4 surrounding the outer periphery of the outer periphery. Reference numeral 13 denotes a hot water jacket that warms the electrolytic cell 1, whereby the electrolytic cell 1 is kept at a temperature of about 80 to 100 ° C. The warm water heating device 12 supplies warm water to the warm water jacket 13.

  The anode chamber 3 is provided with an anode 5, and the cathode chamber 4 is provided with a cathode 6. The anode 5 is a low polarizable carbon electrode. Further, Ni is used as the cathode 6. The anode chamber 3 is provided with a fluorine gas generating port 22 for the fluorine gas generated from the anode chamber 3, and the cathode chamber 4 is provided with a hydrogen gas generating port 23 for the hydrogen gas generated from the cathode chamber 4. Yes. The cathode chamber 4 is connected to an HF supply line 24 for supplying hydrogen fluoride (hereinafter referred to as HF) to the electrolytic cell 1.

  The upper lid 17 of the electrolytic cell 1 has a fluorine gas generating port 22 for fluorine gas generated from the anode chamber 3, a hydrogen gas generating port 23 for hydrogen gas generated from the cathode chamber 4, and the liquid level height of the electrolytic bath 2. HF introduction port 25 from HF supply line 24 for supplying HF when lowered, and first liquid level detection means and second liquid level detection (not shown) for detecting the liquid level heights of anode chamber 3 and cathode chamber 4, respectively. Means and pressure gauges 7 and 8 for detecting the internal pressures of the anode chamber 3 and the cathode chamber 4, respectively, are provided. The fluorine gas generating port 22 and the hydrogen gas generating port 23 are provided with a bent tube formed of a material having corrosion resistance against fluorine gas such as Hastelloy, and splashes from the anode chamber 3 and the cathode chamber 4 are gas. Prevents entry into the line. The HF supply line 24 is covered with a temperature adjusting heater 24a for preventing HF liquefaction.

  The HF adsorption tower 14 includes an HF adsorption tower 14 a and an HF adsorption tower 14 b provided in parallel, and adsorbs HF from a mixed gas of hydrogen and HF discharged from the cathode chamber 4. These HF adsorption tower 14a and HF adsorption tower 14b can be used simultaneously, or any one of them can be used. The HF adsorption tower 14 is provided with pressure gauges 30a and 30b, and it is possible to detect internal clogging. In this way, two HF adsorbing means are arranged in parallel for exchanging the filler, and can be switched to either one by a valve. Here, as a modification, three HF adsorption means may be arranged in parallel. The HF adsorption tower 14 is preferably formed of a material having corrosion resistance to fluorine gas and HF, and is formed of, for example, stainless steel, monel, Ni, fluorine resin, etc., and soda lime is contained therein. The HF in the hydrogen gas is removed by adsorbing the HF that is loaded and passed. Further, while the fluorine gas generator 1000 is in operation, the HF adsorption tower 14 is maintained at about 100 degrees in order to maintain the adsorption performance of the filler such as NaF packed in the HF adsorption tower 14. It is preferable. In the HF adsorption tower 14, heat is generated by contact between HF and NaF as a filler.

  The HF adsorption tower 14 is disposed on the downstream side of a piezo valve (hereinafter sometimes referred to as PV) 10 that maintains the pressure of the electrolytic cell. A vacuum generator 26 is provided between the piezo valve 10 and the HF adsorption tower 14. The vacuum generator 26 reduces the pressure in the gas line 28 by the ejector effect of the gas passing through the gas line 27, and can reduce the gas line 28 without using oil. Intrusion into the oil gas line and the electrolytic cell 1 can be prevented. In addition, nitrogen gas etc. which are inert gas are used for this gas. The piezo valve 10 is provided so that the vacuum generator 26 does not affect the electrolytic cell 1 under reduced pressure. The piezo valve 10 constitutes pressure maintaining means for the electrolytic cell 1.

  The HF adsorption tower 15 is provided with HF adsorption towers 15a and 15b in parallel. Each of the HF adsorption towers 15a and 15b is filled with NaF or the like in order to adsorb HF from the mixed gas of fluorine and HF discharged from the anode chamber 3 and discharge only high-purity fluorine gas. ing. In this way, two HF adsorbing means are arranged in parallel for exchanging the filler, and can be switched to either one by a valve. Here, as a modification, three HF adsorption means may be arranged in parallel. Moreover, the HF adsorption tower 15 is provided with pressure gauges 29a and 29b, and it is possible to detect internal clogging. The HF adsorption tower 15 is also preferably formed of a material having corrosion resistance to fluorine gas and HF, like the HF adsorption tower 14, and examples thereof include stainless steel, monel, and Ni. While the fluorine gas generator 1000 is in operation, the HF adsorption tower 15 is maintained at about 100 degrees in order to maintain the adsorption performance of the filler such as NaF packed in the HF adsorption tower 15. It is preferable. In the HF adsorption tower 15, heat is generated when HF comes in contact with NaF as a filler.

  Piezo valves 9a and 9b, which constitute one of the pressure maintaining means, are provided upstream and downstream of the HF adsorption tower 15. The electrolytic cell 1 and the HF adsorption tower 15 filled with NaF and the like are connected to a compressor. For this reason, since the electrolytic cell 1 and the HF adsorption tower 15 are always decompressed, the piezo valves 9a and 9b are arranged at the above-mentioned locations so that the effect of the decompression is not exerted in the electrolytic cell. The pressure on the electrolytic cell can be maintained by opening and closing the piezo valves 9a and 9b.

  The buffer tank 20 is a storage device that stores the fluorine gas generated from the anode chamber 3.

  The compressor (pressurizer) 21 is a pressurizer that adjusts the pressure in the buffer tank 20. Here, the inside of the compressor 21 will be described with reference to FIG. FIG. 3A is a schematic cross-sectional view of the compressor 21 used in the present embodiment. And FIG.3 (b) is the schematic diagram which expanded a part of main part of Fig.3 (a). In FIG. 3A, the compressor 21 has a gas inlet 51, a gas outlet 52, a valve 53, an O-ring 54, a blower 55, and a gasket 56. A synthetic resin sealing member (hereinafter referred to as a flange sealing member) is used for the O-ring 54, and in order to maintain the purity of the gas passing through the compressor 21, The space between the outside of the compressor 21 is sealed. Accordingly, the synthetic resin is preferably a fluororesin containing 40 to 75% of fluorine. Examples of synthetic resins include polymers such as PCTFE (polytrifluoride ethylene), PVDF (polyvinylidene fluoride), and PVF (polyvinyl fluoride), VF2 (vinylidene fluoride), HFP (hexafluoropolypropylene), What consists of a copolymer (for example, composition of Viton (trademark)) using monomers, such as TFE (tetrafluoroethylene) and PMVE (perfluoromethyl vinyl ether), can be used. Further, the gas inlet 51 and the gas outlet 52 squeeze the O-ring 54 and the gasket 56 from above so that the O-ring 54 becomes a horizontally long ellipse, thereby improving the sealing performance. (In FIG. 3B, the gas outlet 52 is pressed from above, and the gasket 56 is felt to be crushed together with the O-ring 54, so the gas outlet 52 and the gasket 56 are added. May I do it?)

  The integrated gas system 31 includes a pressure sensor, a pressure adjustment valve, a valve, and the like (not shown). The integrated gas system 31 is also stored in the second compartment 102 in the same manner as the pressurizer 21 because the upper limit of the heat resistant temperature is lowered when a valve or the like (not shown) is made of resin. It is preferable.

  The electrical control unit 32 controls the electrical relationship of the entire fluorine gas generator 1000.

  Next, the fluorine gas generator 1000 according to the present embodiment will be described with reference to FIG. The fluorine gas generator 1000 is housed as a unit in a single casing 100 as a whole, and the interior of the casing 100 is divided into three sections by partition walls 104, 105, and 106. The first section 101, the second section 102, and the third section 103 are adjacent to each other. As described above, since the electrolytic cell 1 and the HF adsorption towers 14 and 15 and the compressor 21 are partitioned, they are generated from the electrolytic cell 1 and the HF adsorption towers 14 and 15 when the fluorine gas generator 1000 is operated. It is possible to suppress the heat to be transmitted to the compressor 21. In addition, in the housing | casing of this embodiment, although each division is arrange | positioned so that it may adjoin each of other divisions, you may arrange | position so that it may adjoin any other one division. Further, the inside of the first compartment may be divided into a plurality of partitions by partition walls.

  A suction port (not shown) is provided on the ceiling of the first section 101. By intermittently or continuously performing suction from the suction port, leakage of gas inside the first section 101 to the outside is suppressed.

  Next, the operation of the fluorine gas generator 1000 according to this embodiment will be described. Normally, in a state where electrolysis is normally performed, fluorine gas is generated from the anode 5 and hydrogen gas is generated from the cathode 6. In order to perform electrolysis efficiently, the electrolytic cell 1 is heated by a hot water jacket 13. The temperature of the hot water jacket 13 is adjusted by a thermometer 11 that monitors the temperature of the electrolytic bath and a hot water heater 12 that heats the hot water supplied to the hot water jacket 13. The generated fluorine gas is supplied to the line from the fluorine gas generating port 22. When the electrolytic bath 2 is reduced by a series of electrolysis, a liquid level detecting means (not shown) is activated, and in conjunction with this, HF is supplied to the electrolytic bath 2 from the HF supply line 24 through the HF inlet 25.

  The fluorine gas supplied from the fluorine gas generating port 22 is in a state of being mixed with HF originally present in the electrolytic cell 1. Therefore, the generated fluorine gas is passed through the HF adsorption tower 15 to remove the mixed HF, and high purity fluorine gas is generated. Two or more HF adsorption towers 15 are connected in parallel, and either or one of the HF adsorption towers 15 can be selected and used by a valve disposed on the upstream side and the downstream side of the HF adsorption tower. . The high-purity fluorine gas from which HF has been removed is supplied in a stable manner as needed by a buffer tank 20 arranged by branching the line upstream of the HF adsorption tower 15 as needed. The pressure in the buffer tank 20 is adjusted by the compressor 21.

  The hydrogen gas supplied from the hydrogen gas generating port 23 is in a state of being mixed with HF originally present in the electrolytic cell 1. Therefore, the generated hydrogen gas is passed through the HF adsorption tower 14 to remove corrosive HF. Two (two) HF adsorption towers 14 are also connected in parallel, and both or one of the HF adsorption towers 14 is selected and used by a valve arranged on the upstream side and the downstream side of the HF adsorption tower 14. be able to.

When gas leaks from the fluorine gas generator 1000, a gas detector provided in the first section (not shown) detects the gas leak. The apparatus is configured to make an emergency stop by the detection signal. And it processes by attracting | sucking the gas which leaked from the suction port not shown provided in the ceiling of the 1st division. From this suction port, hydrogen fluoride gas, fluorine gas, hydrogen gas, carbon tetrafluoride gas and the like are discharged. Here, the cause which carbon tetrafluoride gas produces is demonstrated. When electrolysis is performed, hydrogen fluoride generated by the electrolysis reaction enters the pores and grain boundaries of the carbon material used for the anode, and the carbon electrode is distorted and locally collapsed. As a result, the carbon particles constituting the carbon electrode drop off, and the carbon particles dropped into the electrolytic cell 1 react with the generated F ₂ to become carbon tetrafluoride gas.

Example 1
A fluorine gas generator having the same configuration as that of the above embodiment was produced, and this fluorine gas generator was operated. Here, an electrode for fluorine electrolysis (FE-5) (manufactured by Toyo Tanso Co., Ltd.) was used as the anode in the electrolytic cell. Then, the temperature of the flange seal member of the compressor, the gas leakage from the compressor, the possibility of continuous operation for one month of the fluorine gas generator, and the concentration of carbon tetrafluoride gas outside the pressurizer in the second section were examined. . During the operation of the fluorine gas generator, the casing was not evacuated.

(Example 2)
Next, a fluorine gas generator having the same configuration as that of the above embodiment is manufactured, and this fluorine gas generator is operated. During operation, the exhaust in the housing is exhausted from the suction port provided on the ceiling of the first section. went. The fluorine gas generator was operated under the same conditions as in Example 1 except that the exhaust in the housing was performed continuously at an exhaust wind speed of 2.5 to 3.3 m ³ / min. It was measured.

(Comparative Example 1)
Next, the conventional fluorine gas generator shown in FIG. 4 in which the housing was not partitioned by the partition walls was produced, and this fluorine gas generator was operated. Then, the temperature of the flange seal member of the compressor, the gas leakage from the compressor, and the possibility of one-month continuous operation of the fluorine gas generator were examined. Further, the concentration of carbon tetrafluoride gas outside the pressurizer inside the casing was measured. During the operation of the fluorine gas generator, the casing was not evacuated.

(Comparative Example 2)
Next, the fluorine gas generator shown in FIG. 4 is manufactured, this fluorine gas generator is operated, and the exhaust in the casing is exhausted from the suction port (not shown) provided on the ceiling of the casing to an exhaust air velocity of 2.5-3. The fluorine gas generator was operated under the same conditions as in Example 1 except that the operation was performed continuously at ³ m ³ / min, and the measurement was performed in the same manner. In addition, each part to which the code | symbol 1,14,15,20,21,31,32 in the fluorine gas generator 1000 in this embodiment is attached, and code | symbol 201,214, in the fluorine gas generator 2000 shown in FIG. Since the parts denoted by 215, 220, 221, 231, 232 are the same in order, the description may be omitted. The results are shown in Table 1 below.

From Table 1 above, in Examples 1 and 2, in the inspection one month after the start of operation of the fluorine gas generator, there was no gas leakage and no deterioration of the flange seal member of the compressor occurred. Further, there was no particular change in the CF ₄ concentration in the generated gas. On the other hand, in Comparative Example 1, there was no gas leakage during the inspection one month later, but the flange flange member of the compressor was deteriorated. The CF ₄ concentration in the generated gas was high. Further, in Comparative Example 2, on the third day from the start of operation of the fluorine gas generator, the temperature of the compressor rose, the compressor flange seal member deteriorated, and gas leakage occurred, making it unusable. From the above results, in Examples 1 and 2, since the compressor, the electrolytic cell, and the HF adsorption tower are partitioned by the partition walls in the casing, heat transfer from the electrolytic cell and the HF adsorption tower to the compressor is suppressed. It can be seen that the deterioration of the flange seal member of the compressor is suppressed. On the other hand, in Comparative Examples 1 and 2, since the compressor, the electrolytic cell, and the HF adsorption tower were housed in one section without being partitioned, heat was transferred from the electrolytic tank and the HF adsorption tower to the compressor, It turns out that the temperature of the compressor is rising. It was also found that the rise in the temperature of the compressor caused deterioration of the flange seal member, which is a component inside the compressor, and a decrease in the purity of the fluorine gas supplied from the fluorine gas generator.

  The present invention can be changed in design without departing from the scope of the claims, and is not limited to the above-described embodiments and examples.

It is the schematic of the principal part of the fluorine gas generator which concerns on embodiment of this invention. It is a schematic diagram for demonstrating the arrangement configuration of the principal part of the fluorine gas generator which concerns on embodiment of this invention. (A) is the cross-sectional schematic diagram of the compressor 21 used by this embodiment, (b) is the schematic diagram which expanded a part of main part of Fig.3 (a). It is a schematic diagram for demonstrating the arrangement configuration of the principal part of the conventional fluorine gas generator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrolysis tank 2 Electrolytic bath 3 Anode chamber 4 Cathode chamber 5 Anode 6 Cathode 12 Hot water heating device 13 Hot water jacket 14 HF adsorption tower (second adsorption means)
14a, 14b Each HF adsorption tower 15 HF adsorption tower (first adsorption means)
HF adsorption tower 20 of each 15a, 15b Buffer tank (storage means)
21 Compressor (Pressurizing means)
22 Fluorine gas generation port 23 Hydrogen gas generation port 24 HF supply line 25 HF introduction port 31 Integrated gas system 32 Electric control unit 51 Inlet 52 Outlet 53 Valve 54 O-ring 55 Blower 56 Gasket 100 Housing 101 First section 102 First Two sections 104, 105, 106 Partition 1000 Fluorine gas generator

Claims (2)

An electrolytic cell in which an electrolytic bath made of a mixed molten salt containing hydrogen fluoride is formed;
An adsorbing means for discharging a fluorine-containing gas containing fluorine gas generated by electrolyzing the electrolytic bath and adsorbing hydrogen fluoride contained in the fluorine-containing gas;
A pressurizer for pressurizing the fluorine gas of the fluorine-containing gas on which the hydrogen fluoride is adsorbed;
A fluorine gas generator comprising a housing in which the electrolytic cell, the adsorption means, and the pressurizer are accommodated,
In order to maintain the purity of the gas passing through the inside of the pressurizer, the pressurizer has a synthetic resin sealing member for blocking the inside of the pressurizer from the outside of the pressurizer. Is,
In the housing, the pressurizer, the electrolytic cell, and the adsorbing means are partitioned by a partition wall.   2. The fluorine gas generator according to claim 1, wherein the synthetic resin is a fluororesin containing 40 to 75% of fluorine.

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