TW201350191A - Apparatus and method for processing gas - Google Patents

Abstract

Provided is an apparatus which is capable of processing a PFC gas and the like. This apparatus comprises: a channel in which at least some of a gas to be processed is exposed to a high-frequency electric field or ultraviolet irradiation; a catalyst layer to which the gas having passed through the channel is supplied; and a voltage supply unit which applies a bias voltage to the catalyst layer. By processing a gas to be processed, which has been converted into radicals by atmospheric pressure plasma formed by a high-frequency electric field, with the catalyst layer to which a bias voltage is applied, the gas to be processed can be processed at low temperature. The catalyst layer is a platinum catalyst having a porous structure, typically a honeycomb structure, and internally contains a layer that is filled with particulate slaked lime.

Description

Gas treatment device and method

The present invention relates to an apparatus and method for decomposing molecules contained in a gas to be treated such as perfluorocarbon (PFC).

Japanese Laid-Open Patent Publication No. 2005-7341 discloses a method for decomposing an organic halogen compound in order to provide a method and an apparatus for efficiently decomposing an organic halogen compound efficiently by a small device, which is characterized in that an organic solvent such as PFC is used. The halogen compound is mixed with a combustible substance such as propane gas and oxygen or an oxygen-containing gas, and the obtained mixture is subjected to a flame radical reaction by a burner, and the mixture in the reaction is subjected to plasma treatment with a hot plasma apparatus while being activated with alumina. The organic halogen compound is decomposed by contact with a catalyst layer such as titanium dioxide.

[Advanced technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2005-7341

The process of modifying or decomposing the gas is mostly carried out at a high temperature containing several hundred ° C or more. Perfluorocarbon gas (hereinafter referred to as PFC), which is etched and cleaned in a semiconductor manufacturing plant, is stable without toxicity and toxicity, but has a strong greenhouse effect (the global warming coefficient is 6000 to 10 of CO ₂ , 000 times). PFC, considering its stability, generally uses a detoxification method that burns at high temperatures. The acidic fluorine gas (hereinafter referred to as F ₂ ) generated during the detoxification process is dissolved in water and additionally subjected to drainage treatment. The apparatus for treating a gas in this manner is susceptible to corrosion due to exposure to a high-temperature acid gas, and the running cost is high. In addition, in order to ensure the safety of a semiconductor factory that processes a flammable gas, it is necessary to heat and cool the high temperature portion, and it is a factor for increasing the size of the processing equipment and the detoxification device for the water in which the acid gas is dissolved.

Therefore, in the case of a processing apparatus that decomposes and reforms a gas such as PFC, a device that is small and can be cooled at a low temperature and has a low running cost is desired.

An aspect of the present invention is a processing apparatus having a flow path in which at least a part of a gas to be treated is exposed to a high-frequency electric field or ultraviolet ray; and a catalyst layer is supplied with a gas that has passed through the flow path; And a voltage supply unit that applies a bias voltage to the catalyst layer. By applying a bias voltage (biased electric field) to the catalyst layer, the catalyst can be activated, and the gas treatment efficiency can be improved. Furthermore, at least a part of the gas molecules to be treated can be treated at a low temperature and an atmospheric pressure by using a reaction of RF plasma or ultraviolet light generated by a high-frequency electric field. Free radicalization and supply to the catalyst layer. Therefore, it is possible to provide a treatment apparatus which treats (decomposes or reforms) a gas at a low temperature and with high efficiency by a catalyst layer. Therefore, it is possible to provide a gas processing apparatus capable of suppressing corrosion of constituent members of the apparatus due to heat or acid gas, and having high running cost and high safety to the surroundings.

The bias applied to the catalyst layer may be AC or DC, but DC bias is typically preferred. By imparting a charge or a hole to the surface of the catalyst, the catalyst can be activated with low power consumption. Therefore, effects such as photocatalyst can be expected by using a catalyst such as platinum.

Ultraviolet irradiation is a process of attacking and cutting off molecular bonds in the gas to be treated. At the same time, highly reactive oxygen radicals are generated from oxygen in the air to promote processing in the catalyst layer. The ultraviolet ray may be near ultraviolet ray, or may be extremely ultraviolet ray, and the wavelength is short and the energy is high, and vacuum ultraviolet rays (having a wavelength of 200 nm or less) which are easier to shield are preferable. The treatment device preferably contains an ultraviolet source that generates vacuum ultraviolet rays. One of the ultraviolet sources that generate vacuum ultraviolet rays is an excimer light irradiation unit.

It is also effective to generate RF plasma in the treatment target gas using a high frequency power source. By generating RF plasma (atmospheric piezoelectric slurry) in the gas to be processed, molecular bonding of the gas to be treated can be weakened, and generation of oxygen radicals can be promoted.

Preferably, the processing device further includes: a plurality of electrodes positioned on both sides of the flow path to form a high frequency electric field; and a dielectric layer disposed to sandwich the plurality of electrodes. The plurality of electrodes also include members such as a casing that functions substantially as an electrode. The processing gas and the carrier gas are supplied together to the processing apparatus. For example, nitrogen is more difficult to ionize than argon, and from the viewpoint of economy, nitrogen is used as a carrier gas for PFC. In order to form under a nitrogen atmosphere It is necessary to apply a high electric field to the RF plasma, and it is easy to convert from a glow discharge to an arc discharge. However, since the arc discharge is apt to become high temperature, it is preferable to avoid it. By disposing the dielectric layer so as to be sandwiched by the electrodes, it is possible to utilize the dielectric shield discharge, and it is possible to suppress the conversion into an arc discharge by shortening the discharge period.

The dielectric layer is preferably one having a plurality of concavo-convex structures. The convex portion is harder to cause discharge than the concave portion. Therefore, in a state in which a small-area plasma electrode is accumulated, the sum of the discharge areas can be increased, and the time (distance) at which the gas is exposed to the high-frequency electric field can be elongated.

Further, it is effective to arrange the needle electrode upstream of the flow path. When a large amount of gas flows through the flow path, there is a high possibility that the flow path becomes high pressure, and discharge is less likely to occur under high pressure, and when discharge occurs, it is easily converted into an arc discharge. On the other hand, when the width of the widened flow path is reduced, the discharge becomes less likely to cause discharge due to the increase in the electrode interval. Therefore, the needle electrode is provided upstream of the flow path to discharge it, and a part of the gas molecules are ionized, whereby ions as carriers of electrons or holes are generated in the gas. It becomes easy to cause discharge at the downstream of the needle electrode due to an increase in ions in the gas. Therefore, the generation of RF plasma becomes easy, and the time (distance) of the gas passing through the RF plasma can be elongated.

It is preferable that the processing apparatus further has a magnetic field generating unit that is intermittently arranged along the flow path. A typical magnetic field generating unit is a permanent magnet or an electromagnet. By forming an appropriate magnetic field along the flow path, electrons can be trapped in the flow path to expand the discharge region, and the gas containing the radical ions can be smoothly guided along the flow path.

In a processing apparatus in which a plurality of electrodes are arranged concentrically on both sides of a flow path, it is also effective to provide a means for applying a negative potential to the outer electrodes. Since the electrons in the plasma jump back by the negative potential, the surface of the electrode can be suppressed. The loss of electronics. Therefore, the effect of shutting off the plasma and promoting ionization in the plasma (hollow cathode effect) can be obtained, and radicalization can be promoted.

The catalyst layer is typically a carrier containing or supporting platinum. The catalyst layer is made of a metal such as nickel (Ni), molybdenum (Mo), cobalt (Co), platinum (Pt), iron (Fe), or an alloy containing at least two of nickel, iron, and cobalt, or an organic metal. And so on. The catalyst layer may also be a carrier containing or supporting the above metals, alloys or organometallics.

Another aspect of the present invention is a method of treating a gas comprising the following steps.

1. At least a part of the gas to be treated is passed through a flow path that is exposed to a high-frequency electric field or ultraviolet light.

2. The gas that has passed through the flow path is supplied to the biased catalyst layer.

An electrode for forming a high-frequency electric field is disposed on both sides of the flow path so as to form a high-frequency electric field, and the dielectric shielding discharge can be performed. Preferably, the processing target gas is generated by the flow path system. The flow path of the dielectric shield discharge. By using RF plasma (atmospheric plasma) formed by dielectric shielding discharge, a large amount of gas to be treated can be radically (free radically ionized) at a low temperature, and a catalyst can be used to lower the gas by a catalyst reaction. Decompose or upgrade efficiently.

One of the gas to be treated is a person containing carbon fluoride, typically a PFC (perfluorocarbon) gas. According to the above-described processing apparatus and processing method, the PFC gas can be decomposed into carbon dioxide and fluorine to be detoxified. In this case, the catalyst layer of the treatment apparatus is preferably a porous structure and contains a layer (first layer) in which slaked lime (calcium hydroxide (Ca(OH) ₂ )) is filled. Further, it is preferable that the treatment method include a layer containing a gas having passed through the flow path and filled with slaked lime. The catalyst layer is typically a honeycomb structure, and the fluorine generated by the treatment of the gas to be treated is absorbed by the slaked lime, and the inactivation (detoxification) of the catalyst such as platinum due to fluorine can be suppressed. Therefore, it is possible to suppress a decrease in processing efficiency of the processing apparatus.

The catalyst layer is preferably a layer containing hydrated hydrated lime. It is possible to suppress an increase in the resistance of the gas as it passes through the catalyst layer, and it is possible to suppress an increase in the pressure of the flow path in which the RF plasma is formed by the high-frequency electric field. Therefore, it is easy to maintain conditions in which RF plasma is easily generated. Further, since the slaked lime and the fluorine react to form fluorspar (CaF ₂ ), it is easy to recycle the fluorine by recycling the granular slaked lime.

1‧‧‧PFC gas

2‧‧‧Oxygen (air, or a mixture of oxygen and nitrogen)

3‧‧‧ Mixed gas (gas, treatment target gas)

4‧‧‧ mixed gas

5‧‧‧Carbon dioxide

5‧‧‧Dry pump

6‧‧‧Fluorine gas

7‧‧‧Fluorite

10‧‧‧Treatment method (detoxification method)

20‧‧‧UV irradiation unit

21‧‧‧Vacuum UV source (vacuum UV source, excimer lamp)

22‧‧‧UV (Vacuum Ultraviolet (VUV))

23‧‧‧High frequency electric field

24‧‧‧Low-temperature atmospheric piezoelectric slurry (non-equilibrium atmospheric piezoelectric slurry, RF plasma (atmospheric piezoelectric slurry))

25‧‧‧Atmospheric piezoelectric slurry generator (high frequency generator)

26‧‧‧Atmospheric piezoelectric paste

29‧‧‧Flow

31‧‧‧catalyst (catalyst layer, platinum catalyst)

33‧‧‧ hole

35‧‧‧Voltage supply unit

41‧‧‧ slaked lime

50‧‧‧Processing device

50a‧‧‧Processing device

50‧‧‧UV reaction area

51‧‧‧Case (outer casing)

52‧‧‧ gas supply unit

53‧‧‧dry pump

55‧‧‧catalytic reaction zone

56‧‧‧UV reaction area

57‧‧‧UV inlet window (wall)

58‧‧‧Mirror

60‧‧‧Processing device

61‧‧‧Unit 1

62‧‧‧Unit 2

63, 64‧‧‧ electrodes

63a‧‧‧Front or flanged part

63b‧‧‧needle electrode (needle electrode)

64‧‧‧Outer electrode (cylinder electrode, peripheral electrode)

65, 66‧‧‧ dielectric layer

67‧‧‧ Magnet

68‧‧‧Shell

68a‧‧‧ Combined device

69‧‧‧Shell

70‧‧‧Power supply unit

71‧‧‧AC power supply (high frequency power supply, RF power supply)

72‧‧‧matcher (MB)

73‧‧‧ lines

74‧‧‧DC power supply

80‧‧‧Processing device

80‧‧‧Injury device

80‧‧‧ Shell

81‧‧‧Unit 1

82‧‧‧Unit 2

83, 84‧‧‧ electrodes

85, 86‧‧‧ dielectric layer

87‧‧‧unit (magnet)

88‧‧‧needle electrode

89‧‧‧ Shell

89a‧‧‧ Shell

89b‧‧‧ Shell

90‧‧‧Concave structure

91‧‧‧The convex part of the dielectric

95‧‧‧discharge (microplasma, milliplasma)

Fig. 1 is a diagram showing a processing method.

Fig. 2(a) is a view showing a reaction according to ultraviolet rays, and (b) is a view showing a reaction according to a catalyst.

Fig. 3 is a block diagram showing a schematic configuration of a processing apparatus.

Fig. 4 is a block diagram showing a schematic configuration of a different example of the processing device.

Fig. 5 is a block diagram showing a schematic configuration of another different example of the processing apparatus.

Fig. 6 is a block diagram showing a schematic configuration of another different example of the processing apparatus.

In an example of the present invention, PFC (perfluorocarbon) gas such as carbon tetrafluoride (CF ₄ ) used for etching and cleaning of a semiconductor manufacturing or FPD (flat panel display) manufacturing step is shown in FIG. The treatment method of detoxification. In this treatment, the reactivity of the gas molecules is increased by ultraviolet rays or RF plasma, and is brought into contact with a catalyst which is highly activated by a DC bias potential, and is detoxified by oxidizing the gas.

PFC means that the hydrogen of the hydrocarbon CxHy is completely replaced by fluorine (CxFy). The global warming coefficient (GWP) of PFC is 6000 to 10,000 times that of CO ₂ and has a much greater impact on warming than CO ₂ . Moreover, the life in the atmosphere is as long as 10,000 years, and the adverse effects on the environment are strong. In the example shown below, the objective is to treat the PFC and discharge the CO _{2 to} perform the PFC detoxification treatment.

In the past, the PFC decontamination treatment system used high temperatures, and the representative methods were combustion type, electric heating decomposition type, catalytic type and plasma burner type. The bonds in the molecules of the PFC are cut off by heat, and are subjected to a wet treatment after reacting with oxygen. It is necessary to additionally treat the fluorine-based drainage system produced by the wet treatment. The combustion type burns hydrogen or fossil fuels and decomposes the PFC in a high temperature environment of about 1600 °C. Although the efficiency of decontamination is 95%, it requires a lot of fuel. Further, the acid such as hydrogen fluoride (HF) generated by the treatment is exposed to a high temperature environment to cause corrosion of the detoxification device and high running cost. Moreover, the size of the device is several cubic meters, and it is difficult to secure the installation place in the existing semiconductor factory.

The electric heating decomposition type heats the PFC to 800 ° C by an electric furnace and decomposes it. The temperature is lower than that of the combustion type, and the amount of the coating is less likely to be corroded. However, the efficiency of detoxification is 40%. The catalyst type uses a catalyst heated from 650 ° C to 800 ° C to dry out the PFC in a dry manner. Detoxification efficiency system 98 % degree, there are few doubts about corrosion. However, the processing flow rate of 80 LPM is 1/3 of the other way.

The plasma burner type applies electric power to the exhaust gas, and forms a thermal plasma by arc discharge to thermally decompose the PFC. Since the thermoelectricity is to be formed, the power consumption is large, and the hydrogen fluoride generated in the decomposition process is corrosive at a high temperature, and the corrosion is intensified when the hydrofluoric acid (fluoric acid) is formed.

The treatment method (decontamination method) 10 shown in FIG. 1 is based on a combination of radicalization of gas molecules of ultraviolet or RF plasma and a catalyst type which is highly activated by a DC bias potential. At a low temperature, for example, 200 ° C or less suppresses power consumption and suppresses corrosion to improve running cost, and achieves the same degree of decontamination efficiency as the conventional catalyst type. Further, by disposing slaked lime in the catalyst, the fluorine gas generated in the reaction process is adsorbed by slaked lime to achieve dry detoxification and re-recycling of the catalyst activity and fluorine.

In this treatment method (decontamination method) 10, a mixed gas 3 in which PFC gas 1 and oxygen (air, or a mixed gas of oxygen and nitrogen) 2 are mixed is generated in step 11. The PFC gas 1 is diluted to about 2000 ppm with nitrogen as a carrier gas and is discharged from the semiconductor process. Therefore, a method and apparatus for detoxifying a large amount of PFC gas 1 contained in nitrogen gas will be described below as an example.

In step 12, the mixed gas 3 is introduced into the flow path 29 of the ultraviolet ray 22 supplied from the vacuum ultraviolet source (vacuum ultraviolet light source) 21, and the mixed gas 3 is irradiated with the ultraviolet ray 22 to radicalize the mixed gas 3. The high-frequency electric field 23 is applied to the flow path 29 to form a low-temperature atmospheric piezoelectric slurry (non-equilibrium atmospheric piezoelectric slurry) 24, and the mixed gas 3 passing through the flow path 29 is radicalized. In terms of excitation sources that increase the reactivity of PFC, light and electron specific heat are also easier to control energy, The RF plasma 24 generated in the high-frequency electric field 23 is controlled by the range of the low-temperature atmospheric piezoelectric slurry to radically PFC1. Thereby, the reaction is lowered in temperature to achieve low running costs.

In step 13, the radicalized mixed gas 4 is supplied to the platinum catalyst 31 which has been biased to cause oxidation reaction, and the PFC gas 1 is decomposed into carbon dioxide 5 and fluorine gas 6 (oxidation, chemical change, modification). ). Since step 12 is mainly carried out to radicalization at a low temperature, in step 13 and using a catalyst, a sufficient treatment speed can be obtained even at a low temperature. Further, by applying a DC bias to the catalyst, electrons are extracted from the chemical species that have passed through the plasma, and the adsorption and diffusion of the chemical species toward the catalyst surface are promoted, and the PFC is oxidized at a low temperature to be harmless.

As shown in Fig. 2(a), in step 12, the CF bond of the PFC gas 1 (mixed gas 3) is cut by the irradiation of the vacuum ultraviolet light 22 or the RF plasma 24. Further, as shown in Fig. 2(b), in step 13, the charge is exchanged between the hole on the surface of the catalyst 31 which is positively charged by the DC bias voltage and the electron of the radicalized PFC gas 1. Promote oxidation of PFC gas 1. That is, the carbon radical of the radicalized mixed gas 4 is oxidized to carbon dioxide due to contact with the platinum catalyst 31.

In the treatment method 10, the carbon dioxide generated in the step 13 of the oxidation reaction is exhausted by a dry pump or the like. The fluorine gas 6 generated in the step 13 of the oxidation reaction is in the catalyst 31 and is captured by slaked lime (calcium hydroxide, Ca(OH) ₂ ) in step 14 to form calcium fluoride (fluorite, fluorite, CaF _{2 ).} ). Therefore, the fluorine is fixed in the form of fluorite 7 and is safely captured and recovered. The catalyst 31 has a porous structure, for example, a honeycomb structure, and is filled with granular slaked lime 41 inside, and the radicalized mixed gas 4 passing through the flow path 29 is supplied with the catalyst layer 31 filled with the slaked lime 41. Fluorite 7 is used as a flux, an optical material, etc., and is a storage source of fluorine. Therefore, through the setting step 14, recovery and recycling of fluorine can be performed. Further, slaked lime (calcium hydroxide) can be obtained by preliminarily charging quicklime (calcium oxide, CaCO ₃ ) together with hydrated lime to the catalyst layer 31, and capturing the water at the time when fluorite (calcium fluoride) 7 is formed by using quicklime. ) 41 generation.

Fig. 3 shows an example of a processing device (abuse device) for PFC gas. The processing apparatus 60 includes a cylindrical first unit 61 that radicalizes the mixed gas 3 of the PFC gas 1 diluted with nitrogen and oxygen or air 2 through the RF plasma generation region; the second unit 62 of the cylindrical type And storing the platinum catalyst 31 and supplying the radicalized mixed gas 4 through the platinum catalyst 31 and oxidizing; the gas supply unit 52 supplying the mixed gas 3 to the upstream first unit 61; and the dry pump 53, The generated carbon dioxide 5 is discharged from the second unit 62 downstream.

In the processing device 60, the first unit 61 performs a step 12 of radically activating the mixed gas 1 (3?). The catalyst layer 31 accommodated in the second unit 62 is a ceramic contact medium that is porous in platinum, and specifically has a honeycomb structure. The pores 33 of the honeycomb structure of the catalyst layer 31 are filled with granular slaked lime 41. Therefore, the step 13 of oxidizing the reductive unit and the step 14 of stabilizing the fluorine gas 6 into the fluorspar are performed simultaneously or in parallel in the second unit 62.

The first unit 61 includes a cylindrical stainless steel outer casing 69, two electrodes 63 and 64 which are concentrically arranged inside the outer casing 69, and a gap between the electrodes 63 and 64. The dielectric layers 65 and 66 and the dielectric layers 65 and 66 serve as a flow path 29 through which the mixed gas 3 to be processed passes. An example of a material suitable for the dielectric layers 65 and 66 is PTFE. (polytetrafluoroethylene).

The inner electrode 63 is a rod-shaped electrode that is expanded toward the inlet side of the mixed gas 3 of the gas supply unit 52, and the plurality of needle electrodes 63b are expanded in the direction of the electrode 64 facing the outer side. A brim-like portion 63a. The outer electrode 64 is a cylindrical electrode, and a plurality of magnets 67 are intermittently arranged along the axial direction inside.

The processing device 60 includes a power supply unit 70 for supplying a high-frequency voltage to the electrodes 63 and 64 of the first unit 61, and a high-frequency electric field to be formed in the flow path 29 to generate RF plasma. The power supply unit 70 includes an AC power source (high-frequency power source, RF power source) 71 and a matcher (MB) 72, and supplies the high-frequency power to the inner electrode 63 via the matching unit 72. The power supply unit 70 further includes a line 73 that grounds the outer casing 69 and a DC power source 74 that gives a negative potential to the outer electrode 64.

As explained previously, the dilution of the PFC uses nitrogen (N ₂ ) gas. Therefore, in the first unit 61, it is preferable to generate a low-temperature plasma at a pressure close to atmospheric pressure when considering practicality. In order to obtain a low-temperature plasma, it is necessary to cause a glow discharge or a streamer discharge, and it is necessary to avoid an arc discharge which is liable to form a high temperature. In terms of ionization, the N ₂ gas requires a high electric field than the Ar gas, and when a high electric field is applied at a pressure close to atmospheric pressure, it becomes easy to convert into an arc discharge. Then, in the first unit 61, the dielectric shield discharge electrode structure and the needle electrode 63b of the electrodes 63 and 64 are arranged in the same manner as the sandwich dielectrics 65 and 66, and the glow discharge is caused by the high electric field while the needle electrode 63b is realized. Dielectric shielding discharge is used to improve the efficiency of decontamination.

In the case of dielectric barrier discharge, the application of an electric field from the RF power source 71 is hindered by a dielectric such as PTFE or quartz, which is not in the high electric field. The polarity is reversed under long time application. Therefore, the discharge time can be limited to a short time, and the plasma formed between the electrodes can be prevented from becoming high in temperature. In this case, since fluorine generated by the decomposition of the PFC easily etches quartz, quartz (glass) is not suitable as a dielectric. A device for performing decomposition or modification of other gases is suitable for using quartz as a dielectric when considering cost, strength, and the like.

Further, in the first unit 61, since the cap electrode or the flange-shaped portion 63a is provided in the center electrode 63, the electrode interval is narrowed in the vicinity of the gas introduction port of the flow path 29 of the mixed gas 3, and the gas 3 is easily ionized. Construction. Then, the needle electrode 63b is placed in the vicinity of the gas introduction port. With these structures, a glow discharge is once performed in the vicinity of the gas introduction port to ionize a part of the gas molecules to form ions and become electron carriers. Therefore, after that, it becomes easy to form a plasma inside the flow path 29, and even a shape of an electrode having a wide discharge area becomes easy to form a plasma.

In the first unit 61, a negative potential is applied to the outer cylindrical electrode 64 to form a hollow cathode. By forming the outer peripheral electrode 64 into a hollow cathode, the electrons in the plasma are prevented from being trapped by the negative potential to suppress the loss of electrons on the surface of the electrode, and the effect of promoting ionization in the plasma can be obtained (hollow cathode effect). .

Further, a disk-shaped magnet 67 is intermittently arranged in the axial direction inside the cylindrical electrode 64, and the closed electrons are subjected to a cyclotron acceleration motion along the external magnetic field generated by the magnet 67 while being on the cylindrical electrode 64. The diametrical movement moves along with the free radicals and/or radical ions in the downstream direction of the gas. By such a mechanism, the discharge region inside the flow path 29 is enlarged, and the radicalization of the mixed gas 3 is promoted. The direction of the external magnetic field may be circumferential or axial. As long as you can get the effect of turning off the electronic.

In this manner, in the first unit 61, plasma (RF plasma or atmospheric piezoelectric slurry) is formed in the flow path 29 at a low atmospheric pressure and at a low temperature of 200 ° C or lower. After the determination of the abatement efficiency by the Fourier transform infrared spectrophotometer (FT-IR) in the experimental stage, the plasma with a large nitrogen flow rate can be stably formed, and the flow ratio of oxygen to PFC is 1:1 or 3:2. The ratio of oxygen is large, and the result of good detoxification is good. It can be considered that the electrode having a large nitrogen flow rate is stable in temperature and stable in discharge.

The Fourier transform infrared spectrophotometer irradiates infrared rays to the measurement target, and since the energy of each wavelength of the absorbed infrared rays is inherent in the substance, it is possible to evaluate the molecules present in the object and their concentrations. A measuring device suitable for a method for evaluating characteristics of a PFC detoxification device.

In the processing device 60, the mixed gas 4 that has been radicalized in the first unit 61 is supplied to the second unit 62 that forms the catalyst reaction region. The second unit 62 includes a cylindrical stainless steel outer casing 68 and a catalyst layer 31 provided inside. In the second unit 62, the radicalized mixed gas 4 is oxidized and decomposed by contact with the catalyst layer 31 through the pores 33 of the catalyst layer 31. The fluorine gas 6 formed by the oxidation unit reacts with the slaked lime 41 filled in the pores 33 of the honeycomb structure, and is fixed in the form of the fluorite 7. Therefore, in the processing device 60, the PFC 1 in the mixed gas 3 is decomposed, the generated fluorine gas 6 is fixed inside the catalyst layer 31, and the carbon dioxide 5 is exhausted from the processing device 60 by the dry pump 53.

The processing device 60 further includes a voltage supply unit 35 that applies a potential to the catalyst layer 31. The voltage supply unit 35 supplies a DC voltage (DC electric field) The catalyst layer 31, the surface of the germanium catalyst layer 31 is applied with a positive bias (high potential) with respect to the grounded outer casing 68. By applying a positive bias to the surface of the catalyst layer 31, a positive charge can be forcibly imparted to the surface of the catalyst layer 31 to which the radicalized mixed gas 4 is in contact. Therefore, charge is easily transferred between the mixed gas 4 which is negatively ionized (radical ionized) by radicalization. Therefore, the decomposition of PFC1 in the catalyst layer 31 is further promoted. The catalyst layer 31 is activated by a DC bias electric field, and the effects equivalent to those of the photocatalyst can be similarly applied.

The more the amount of the slaked lime 41 filled in the porous body 33 of the catalyst layer 31, the more easily the fluorine is removed. However, the conductance of the gas passing through the catalyst layer 31 is lowered, and the differential pressure is increased. Therefore, the pressure inside the flow path 29 of the upstream first unit 61 rises, and the plasma may be unstable. Therefore, the filling amount of the slaked lime 41 is selected to evaluate the amount of fluorine removal and the efficiency of the detoxification, and it is possible to select a filling amount which is the highest fluorine removal amount while maintaining the high decontamination efficiency of the target, for example, 95%.

The outer casing 69 of the first unit 61 and the outer casing 68 of the second unit 62 are detachably connected by a flange type coupling device 68a. Therefore, after a predetermined processing time elapses, the second unit 62 is removed, and the slaked lime 41 of the catalyst layer 31 is replenished, whereby the fluorite 7 can be recovered from the slaked lime 41. The recovered fluorspar 7 is used as a fluorine resource. Thus, the removal and re-recycling of fluorine in the processing device 60 can be achieved in a dry process.

Fig. 4 shows a different example of a processing device (abatement device) of PFC gas. The processing device 80 further includes: a first unit 81 that radicalizes the mixed gas containing PFC by RF plasma; and a second unit 82 that oxidizes the radicalized mixed gas 4 by the platinum catalyst 31; A gas supply unit 52 for the gas 3; and a dry pump 53 for discharging the carbon dioxide 5.

The first unit 81 includes a box-shaped stainless steel case 89; flat-type electrodes 83 and 84 that are alternately arranged in parallel so as to form a zigzag channel 29 inside the case 89; and cover each electrode 83 and The dielectric layers 85 and 86 of 84. The processing device 80 having electrodes of parallel plate type is suitable for processing a large flow of the mixed gas 3. Since the processing target gas 3 becomes a large flow rate, the speed at which the charged particles pass through the gas flow path to which the electric field is applied also becomes faster. Therefore, the time for accelerating electrons and ions becomes short, and it becomes difficult to cause discharge.

In the first unit 81, first, in the same manner as the above-described processing apparatus 60, the electrodes 83 and 84 are placed to sandwich the dielectric layers 85 and 86 to generate dielectric shield discharge. Thereby, the glow discharge is easily generated by narrowing the electrodes and relatively increasing the electric field intensity, and the electric time is scaled to prevent the conversion from the glow discharge to the arc discharge. Further, the needle electrode 88 is provided on the gas introduction port side of the flow path 29, and a higher electric field is locally generated to cause discharge to be more reliably generated on the upstream side of the flow path 29. Accordingly, carriers (ions) that generate electric charges in the gas are likely to generate plasma in the entire flow path 29. Further, since the discharge is likely to occur, the voltage to be applied can be lowered, power consumption can be reduced, and plasma can be generated at a low temperature.

In this device 80, the outer casing 89 and the electrode 84 are grounded, and are discharged between the electrode 83 connected to the RF power source 71 and the outer casing 89 and/or the electrode 84 to generate plasma. The needle electrode 88 may be provided at any of the electrodes 83, 84 or the outer casing 89, but in this example, the outer casing 89 is disposed to protrude toward the electrode 83. The needle electrode 88 may be any needle-shaped cusp, and may be a rod-shaped or appropriately shaped convex portion as long as it can generate an unbalanced electric field.

Further, in the first unit 81, the flat electrodes 83 and 84 are alternately arranged, and a zigzag flow path 29 is formed inside the outer casing 89. By widening and lengthening the width of the gas flow path 29 to which the electric field is applied, it is possible to ensure the time for acceleration even when the mixed gas 3 having a large flow rate is supplied, and it is possible to maintain a large kinetic energy even with the same electric field.

The flow path 29 is a zigzag or a snakewalker, and a curved portion having a large curvature is generated in the flow path 29, and the charged portion is decelerated due to a change in the direction of rapid acceleration. Therefore, the magnetic field is prevented from decelerating by the magnetic field. Specifically, a unit (magnet) 87 for forming a magnetic field is disposed at the tips of the electrodes 83 and 84, and the orbit of the radical ions in the gas is adjusted along the magnetic field to assist the movement of the radical ions. Thereby, the charged particles in the gas can be prevented from decelerating, and the collision with the electrode or the outer casing can be suppressed to cause the charged particles to be destroyed.

When a large flow rate of gas is caused to cause a high pressure in the inside of the container (in the flow path), discharge is less likely to occur, and even if discharge is caused, the risk of switching to arc discharge becomes large. The arc discharge system is easily accompanied by high-heat plasma, which causes a large power consumption. In order to avoid the formation of a high pressure in the container, it is effective to increase the conductance of the gas, so that it is preferable to increase the sectional area of the gas flow path 29. Further, since it is difficult to discharge the electrode by taking the interval therebetween, it is effective to increase the area of the electrode when the abatement device 80 is required to be electrically operated. On the other hand, when the electrode area is increased, the problem of a large area of the atmospheric piezoelectric slurry is caused, and dispersion of the discharge portion becomes difficult.

In the processing apparatus 80, a plurality of minute concavo-convex structures 90 are provided to the dielectric layers 85 and 86. In the convex portion 91 of the dielectric material, it is difficult to cause discharge, and in principle, a state in which a small-area plasma electrode is accumulated is formed. In this way, in electricity A large number of minute discharges (microplasma, milliplasma) 95 are generated in the entirety, and the mixed gas 3 can be freely radicalized. One method of introducing the minute uneven structure 90 is to emboss the dielectric sheets forming the dielectric layers 85 and 86 in advance.

In the first unit 81 of the processing device 80, a plurality of electrodes 83 connected to the RF power source 71 via the matching unit 72 and a plurality of ground electrodes 84 are combined with each other to form a flow path 29 of the gas 3. The outer casing 89 of the first unit 81 includes a casing 89a of a right half in which a plurality of electrodes 83 are comb-shaped, and a casing 89b of a left half in which a plurality of electrodes 84 are attached in a comb shape. The first casings 81 are formed by the outer casings 89a and 89b.

The second unit 82 that is supplied with the gas 4 that has been radicalized by the first unit 81 has a configuration that is identical to the shape of the first unit 81, and has a configuration common to the second unit 62 of the processing device 60 described above. . The second unit 82 of the processing apparatus 80 is also attached to the first unit 81 so that the slaked lime 41 can be easily replenished and the fluorite 7 can be easily recovered.

Fig. 5 shows another different example of the processing device (abuse device) of the PFC gas. The processing device 50 is configured to perform the above-described radicalization step 12, the step 13 of oxidizing the catalyst by the catalyst, and the step 14 of stabilizing the fluorine gas 6 into the fluorspar inside the chamber 51, simultaneously or in parallel. get on. The step 11 of mixing the PFC gas 1 and the oxygen (air) 2 in the chamber 51 may also be performed simultaneously or in parallel.

The processing apparatus 50 includes a chamber (outer casing) 51 that houses the platinum catalyst 31 and forms a path for the mixed gas 3 to pass through the platinum catalyst 31 and efficiently contacts the gas supply unit 52, and supplies the PFC gas to the chamber 51. a mixed gas 3 mixed with oxygen 2; and a dry pump 53 that discharges the generated carbon dioxide 5 from the chamber 51. The chamber 51 includes a catalyst reaction region 55 in which a catalyst (catalyst layer) 31 and an ultraviolet reaction region 56 are provided, and is disposed at an upper portion (upstream) of the catalyst reaction region 55. A part of the outer wall of the ultraviolet ray reaction region 56 of the chamber 51, for example, the upper surface (upper wall) of the chamber 51 is a wall (ultraviolet introduction window) 57 which is transparent (transparent) with respect to ultraviolet rays (vacuum ultraviolet rays). For example, the ultraviolet light introduction window 57 is made of calcium fluoride having high transmittance of short-wavelength light.

The processing apparatus 50 further includes an ultraviolet irradiation unit 20 disposed at a position facing the ultraviolet light introduction window 57. The ultraviolet irradiation unit 20 of this example includes an excimer lamp as the ultraviolet source 21. The excimer lamp 21 can efficiently output an ultraviolet light source of a vacuum ultraviolet ray (VUV) 22 having a wavelength of about 180 nm or less, and can efficiently supply the vacuum ultraviolet ray 22 to the ultraviolet ray reaction region 56 of the chamber 51 via the ultraviolet ray introduction window 57.

The chamber 51 is disposed at a position facing the ultraviolet ray introduction window 57. For example, a mirror 58 for reflecting ultraviolet rays is provided on the bottom surface of the chamber 51. In the chamber 51, the catalyst reaction region 55 is sandwiched by the ultraviolet ray introduction window 57 and the mirror 58, and the vacuum ultraviolet ray (ultraviolet light) 22 supplied from the ultraviolet ray introduction window 57 is reflected by the mirror 58 to reciprocate in the ultraviolet ray reaction region. 56 and the catalyst reaction zone 55 are such that the attenuation of the vacuum ultraviolet rays 22 in the chamber 51 is suppressed. Therefore, not only the ultraviolet ray reaction region 56, but also the mixed gas 3 and the vacuum ultraviolet ray 22 in the catalyst reaction region 55 react to promote radicalization of the mixed gas 3.

Similarly to the processing devices 60 and 80 described above, the processing device 50 includes a voltage supply unit 35 that applies a positive (high potential) bias voltage to the catalyst layer 31. The catalyst layer 31 of this example is also a porous ceramic contact medium in which platinum is supported, and the pores 33 of the honeycomb structure are filled with granular slaked lime 41.

In the processing device 50, the ultraviolet ray reaction region 56 and the catalyst reaction region 55 are continuously formed inside one chamber 51, and a mirror 58 is provided on the outlet side of the catalyst reaction region 55 to cause the vacuum ultraviolet light 22 to be reflected. Media reaction area 55. Therefore, in the catalyst reaction region 55, the radical reaction of the ultraviolet rays 22 and the oxidation-reduction reaction according to the catalyst 31 are simultaneously and in parallel in the catalyst reaction region 55. Therefore, the mixed gas 4 which is radicalized by ultraviolet irradiation or the like is recombined, and the radicalized oxygen is brought into contact with the catalyst 31 before being stabilized by oxidation, and is oxidized by the action of the catalyst 31. Therefore, PFC1 can be efficiently decomposed.

Fig. 6 shows another different example of the processing device (abuse device) of the PFC gas. In this processing apparatus 50a, RF plasma (atmospheric piezoelectric slurry) 24 is generated in the ultraviolet reaction region 56 of the chamber 51 as an ultraviolet source. The processing device 50 includes an atmospheric piezoelectric slurry generating device (high-frequency generating device) 25 that applies a high-frequency voltage to the mixed gas 3 introduced into the ultraviolet-ray reaction region 56. The atmospheric piezoelectric slurry 26 may be generated in the ultraviolet ray reaction region 56, and the vacuum ultraviolet ray 22 derived from the ultraviolet ray source of the excimer lamp 21 or the like may be irradiated to the ultraviolet ray reaction region 56. The other configuration of the processing device 50a is common to the processing device 50 shown in FIG.

In this processing apparatus 50a, the atmospheric piezoelectric slurry 26 is generated in the ultraviolet ray reaction region 50. Therefore, the radicalization of the mixed gas 3 is further promoted by the ionization of the plasma. Therefore, the decomposition of the PFC gas 1 can be performed more efficiently.

As explained above, with the gas treatment device of the present invention, A process of radically treating a gas to be treated at a low temperature by ultraviolet irradiation or RF plasma and at a pressure of atmospheric pressure or near atmospheric pressure, and then a radicalized gas and a catalyst layer to which a high potential bias is applied The treatment of the reaction is combined to carry out a treatment for detoxifying or upgrading the gas. Therefore, according to the processing apparatus of the present invention, for example, the treatment of detoxifying the PFC gas can be realized under atmospheric pressure and at a low temperature. In the present specification, the conditions and configuration for forming the atmospheric piezoelectric slurry at a low temperature when the processing target gas is a large flow rate, for example, when it is supplied in a few hundred LPMs, is disclosed. By reliably generating atmospheric piezoelectric slurry (unbalanced plasma) at a low temperature, the power consumption of the processing apparatus can be suppressed to about 10 kW or less, and a power saving type processing apparatus can be provided.

Further, in the decontamination treatment of the PFC, when a corrosive gas such as fluorine is generated during the treatment and becomes a high temperature, the corrosion due to the acid is remarkable, and the maintenance frequency is high. In the processing apparatus of the present invention, since the gas can be treated at a low temperature, it is possible to provide an economical processing apparatus capable of suppressing generation of corrosion and the like and having a low warranty frequency. In addition, as for the source of the processing target gas such as a semiconductor factory, there are many places where flammable gas is often used. From the viewpoint of the risk of fire, etc., it is difficult to install a device that becomes high in such a place. In the case of the processing apparatus of the present invention, it is easy to install in such a place, and gas treatment can be performed at or near the source of the processing target gas. Since this also reduces the equipment and cost of accumulating or transporting the gas to be processed, the processing apparatus of the present invention is economical.

The fluorine acid produced by dissolving fluorine in water according to the detoxification treatment of PFC causes corrosion of the device. Further, it is a space in which a tank or a tank for performing fluorine-based water treatment needs to be placed. In terms of adsorption mode and catalyst mode, It is said that how to deal with the problems of adsorbents and catalysts that have been used. The treatment apparatus and method of the present invention comprise a porous catalyst, and the pores are filled with granular slaked lime, and the fluorine is recovered in the form of fluorite. Since the fluorine recovery process is dried, it is necessary to make the entire equipment simple. Further, since the fluorine can be re-resourced while protecting the catalyst, the transmission can suppress deterioration of the performance of the processing apparatus and recycle the fluorine, thereby providing a more economical processing apparatus.

Further, since the processing apparatus of the present invention can perform gas treatment at a low temperature, it takes a small amount of cost and space for the protection function of the heat-insulating material or the like, and it is possible to avoid a situation in which the processing target gas expands and the processing volume is increased. The processing apparatus of the present invention is dependent on the processing flow rate, and can have a vertical and horizontal height of about 1 m to 2 m, and can be sufficiently provided even in a small semiconductor factory having a limited installation space.

Since the detoxification device of the PFC gas included in the present invention is downsized, it is possible to obtain an effect of introducing the semiconductor semiconductor or the FPD production line without changing the layout. Moreover, the decontamination treatment of the PFC gas can be reduced, so that the environmental load can be reduced, and the fossil fuel used for detoxification of the warming gas can be reduced to the limit. Moreover, since the discharge of the greenhouse gas is reduced by the low power consumption, it is possible to provide a more power-saving product. Further, even if the decomposition rate of the monomer of the treatment apparatus 50 is about 70%, the decomposition rate of the final PFC gas can be increased to about 99% by combining in multiple stages.

Further, the above-described processing apparatus of the present invention is described by a PFC gas detoxification apparatus, but the processing apparatus is not limited to PFC gas, and may be used for treatment of other warming gases or HFC (hydrogen fluoride) generated by a semiconductor process. Treatment of other gases such as carbon compounds), SF ₆ (sulfur hexafluoride), and SiH ₄ (decane). Further, a gas processing system containing PFC gas may be constructed by being connected to a processing device of SiH ₄ .

In addition, even if you focus on the PFC gas decontamination device, it will not only help the heating measures of semiconductor and liquid crystal manufacturing plants, but also ship equipment workshops and ships, aircraft engine workshops and airports that use PFC as a fire extinguishing agent. Warranty fields, large-scale chemical joint laboratories, etc. are effective as detoxification devices for reducing warm gas. It can also be applied to the fields of sterilization and cleaning of medical equipment, utensils, and utensils, which are used in various medical facilities.

1‧‧‧PFC gas

3‧‧‧ mixed gas

4‧‧‧ mixed gas

22‧‧‧vacuum ultraviolet light

24‧‧‧RF plasma

31‧‧‧ Platinum Catalyst

Claims (11)

A processing device having a flow path in which at least a part of a gas to be treated is exposed to a high-frequency electric field or ultraviolet light; a catalyst layer supplied with a gas that has passed through the flow path; and a voltage supply unit that touches the aforementioned The dielectric layer applies a bias voltage. The processing device of claim 1, further comprising: a plurality of electrodes positioned on both sides of the flow path to form a high frequency electric field; and a dielectric layer disposed to sandwich the plurality of electrodes. The processing device of claim 2, wherein the dielectric layer comprises a plurality of concavo-convex structures. A processing apparatus according to claim 2 or 3, further comprising: a needle electrode disposed upstream of the flow path. The processing apparatus according to any one of claims 2 to 4, further comprising: a magnetic field generating unit that is intermittently arranged along the flow path. The processing device according to any one of claims 2 to 5, wherein the plurality of electrodes have: a plurality of electrodes arranged concentrically on both sides of the flow path; A unit of a negative potential is applied to the electrodes on the outer side of the plurality of electrodes arranged concentrically. The processing apparatus according to any one of claims 1 to 6, wherein the catalyst layer is of a porous structure and comprises a layer filled with slaked lime inside. The processing apparatus according to any one of claims 1 to 6, wherein the catalyst layer is a porous structure and includes a layer filled with granular slaked lime. A method for treating a gas includes: passing at least a part of a gas to be processed through a flow path exposed to a high-frequency electric field or ultraviolet rays, and supplying a gas having passed through the flow path to a catalyst layer to which a bias is applied. The method for treating a gas according to the ninth aspect of the invention, wherein an electrode for forming a high-frequency electric field is disposed in a manner of sandwiching a dielectric layer on both sides of the flow path, and the flow path includes The treatment target gas passes through the aforementioned flow path for generating a dielectric shield discharge. The method for treating a gas according to claim 9 or 10, wherein the catalyst layer is a porous structure and includes a layer filled with slaked lime inside, and the supplying comprises supplying a gas that has passed through the flow path. There is a layer of the aforementioned slaked lime.