Exhaust gas treatment device

Abstract

To provide an exhaust gas treatment device capable of efficiently removing a toxic gas contained in an exhaust gas without being enlarged.SOLUTION: An exhaust gas treatment device 100 comprises: a body 1 having a flow path 1a formed to allow flowing of a liquid; an exhaust gas supply line 2 connected to the body 1 to supply an exhaust gas to the flow path 1a through which the liquid flows; a suction unit 3 that sucks the exhaust gas from the exhaust gas supply line 2 to the flow path 1a; a low-temperature plasma generator 5 that generates low-temperature plasma in the flow path 1a and dissolves a toxic gas; and a discharge line 7 for discharging the exhaust gas passed from the body 1 through the low-temperature plasma generator 5.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an exhaust gas treatment device that decomposes and treats exhaust gas containing gases harmful to the human body (eg, silane gas (SiH4)) and / or gases harmful to the environment (eg, global warming gases and ozone layer depleting gases). [Background technology]

[0002] Gases that are harmful to the human body and / or the environment (hereinafter referred to simply as "harmful gases") are used in various industrial fields. For example, semiconductor manufacturing equipment emits exhaust gases that contain flammable harmful gases such as silane gas (SiH4) or halogen-based harmful gases such as NF3, ClF3, SF6, CHF3, C2F6, and CF4.

[0003] Such exhaust gas cannot be released directly into the atmosphere. Therefore, it is common practice to introduce the exhaust gas containing harmful gases into an exhaust gas treatment device to render the harmful gases harmless. As a method for rendering the harmful gases in the exhaust gas harmless, for example, a combustion treatment (see, for example, Patent Document 1) in which the harmful gases are burned using a flame generated by a burner is widely used. Furthermore, a plasma treatment is also known in which a thermal plasma is generated in a plasma generation section and the harmful gases are decomposed by this thermal plasma. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2008-161861 A Summary of the Invention [Problem to be solved by the invention]

[0005] In both the combustion treatment and the plasma treatment, the treatment part of the exhaust gas becomes hot. More specifically, in the combustion treatment, the burner itself where the flame is formed and its surroundings become hot, and the burner itself and the equipment around the burner become significantly worn out. In the plasma treatment, the plasma generating part which generates the thermal plasma and its surroundings become hot, and the plasma generating part itself such as the plasma electrode and the equipment around the plasma generating part become significantly worn out.

[0006] Furthermore, in both the combustion treatment and plasma treatment, the exhaust gas after treatment reaches a very high temperature, so equipment for cooling the treated exhaust gas (e.g., a scrubber) is required. Depending on the type of harmful gas contained in the exhaust gas to be treated, the exhaust gas after the combustion treatment or plasma treatment may contain by-products such as dust (e.g., silicon dioxide) and corrosive gases (e.g., hydrogen fluoride). Equipment for removing these by-products from the treated exhaust gas is also required. Therefore, in conventional exhaust gas treatment methods, the equipment tends to be large, and there is a risk that the exhaust gas treatment equipment will be expensive.

[0007] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide an exhaust gas treatment device capable of efficiently removing toxic gases contained in exhaust gases without increasing the size of the device. [Means for solving the problem]

[0008] In one aspect, an exhaust gas treatment device is provided that neutralizes harmful gases contained in exhaust gas, the exhaust gas treatment device comprising: a main body having a flow path through which a liquid flows; an exhaust gas supply line connected to the main body and supplying the exhaust gas to the flow path through which the liquid flows; an suction device that sucks the exhaust gas from the exhaust gas supply line to the flow path; a low-temperature plasma generator that generates low-temperature plasma in the flow path to decompose the harmful gas; and a discharge line that discharges the exhaust gas that has passed through the low-temperature plasma generator from the main body.

[0009] In one aspect, an exhaust gas treatment device is provided that neutralizes harmful gases contained in exhaust gas, the exhaust gas treatment device comprising: a main body having a flow path through which a liquid flows; an exhaust gas supply line connected to the main body and supplying the exhaust gas to the flow path through which the liquid flows; an suction device that sucks the exhaust gas from the exhaust gas supply line to the flow path; a low-temperature plasma generation device that generates low-temperature plasma in the exhaust gas supply line and decomposes the harmful gas; and a discharge line that discharges exhaust gas containing the harmful gas decomposed by the low-temperature plasma from the main body.

[0010] In one embodiment, the suction device includes an ejector disposed in the flow path upstream of the low-temperature plasma generator in a flow direction of the liquid, and a driving fluid of the ejector is the liquid. In one aspect, the suction device includes an ejector arranged in the exhaust line, and by supplying a driving fluid to the ejector, the internal space of the main body is reduced in pressure and the exhaust gas is sucked from the exhaust gas supply line into the main body. In one embodiment, the exhaust gas treatment device further includes a reflux mechanism for reversing a portion of the liquid and exhaust gas flowing through the flow path to increase the time that the liquid and the exhaust gas remain in the low-temperature plasma generator, the reflux mechanism including a first tapered tube connected to a wall of the flow path and narrowing toward the upstream side in the flow direction of the liquid, and a second tapered tube arranged with a gap from the flow path upstream of the first tapered tube in the flow direction of the liquid, and dividing the liquid and the exhaust gas into a first flow toward the wall of the flow path and a second flow flowing through the center of the flow path, and the first tapered tube causes the first flow to flow back through the flow path toward the second flow.

[0011] In one embodiment, the plasma generating device includes a high-voltage power supply device and at least a pair of a first electrode and a second electrode arranged in the flow path, and the high-voltage power supply generates low-temperature plasma between the first electrode and the second electrode. In one embodiment, the plasma generating device includes a microwave generating device capable of radiating microwaves, a waveguide section for propagating the microwaves, a matching section arranged within the waveguide section for adjusting the impedance of the microwaves, and a slot antenna for concentrating the electric field generated by the microwaves, and the exhaust gas in the liquid is converted into low-temperature plasma on the surface of the slot antenna. In one embodiment, a part or all of the outer surface of the first electrode and / or the second electrode is covered with a dielectric material.

[0012] In one embodiment, the harmful gas is a fluorine compound, a nitrogen compound, or a silane-based compound, and the liquid is pure water, ultrapure water, ion-exchanged water, or an electrolyte. In one embodiment, the atmosphere in the interior space of the body is maintained at atmospheric or subatmospheric pressure while treating the exhaust gas. In one embodiment, the exhaust gas supply line extends to the body from a vacuum pump connected to a process chamber of a semiconductor manufacturing device, or extends to the body from an exhaust gas processing device connected to the vacuum pump. In one embodiment, the exhaust gas supply line is built into or integrated with a vacuum pump connected to a process chamber of a semiconductor manufacturing device, and the main body is directly connected to the vacuum pump.

[0013] In one aspect, the exhaust line extends from the body to a wet exhaust gas treatment device, a combustion exhaust gas treatment device, or a dry exhaust gas treatment device. In one embodiment, the second electrode is formed with at least one exhaust gas inlet for introducing the exhaust gas into the liquid, and the exhaust gas supply line is connected to the second electrode in which the exhaust gas inlet is formed. In one embodiment, the plasma generation device includes a plurality of pairs of a first electrode and a second electrode, or includes a first electrode having a plurality of electrode bars and a second electrode. Effect of the Invention

[0014] According to the present invention, harmful gases are decomposed by low-temperature plasma, so that cooling equipment (eg, scrubber) that is necessary in conventional exhaust gas treatment devices is not necessary, and the exhaust gas treatment device can be made smaller. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram showing an exhaust gas treatment device according to one embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing a low-temperature plasma generating unit according to one embodiment. [Diagram 3] FIG. 3 is a schematic diagram showing a low-temperature plasma generation device according to another embodiment. [Figure 4] FIG. 4 is a schematic diagram showing an example of a circulation mechanism disposed in the main body. [Diagram 5] FIG. 5 is a schematic diagram of an exhaust gas treatment device according to another embodiment. [Figure 6] FIG. 6(a) is a perspective view showing another example of the second electrode, and FIG. 6(b) is a perspective view showing yet another example of the second electrode. [Figure 7] FIG. 7(a) is a perspective view showing another example of the first electrode, and FIG. 7(b) is a perspective view showing yet another example of the first electrode. [Figure 8] FIG. 8 is a schematic diagram of an exhaust gas treatment device according to still another embodiment. [Figure 9] FIG. 9 is a diagram showing an example of an exhaust gas treatment process system in which an exhaust gas treatment device is arranged. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram showing an exhaust gas treatment device according to an embodiment. The exhaust gas treatment device shown in Fig. 1 is a device for rendering harmful gases contained in exhaust gas harmless. Exhaust gas is discharged, for example, from a process chamber of a semiconductor manufacturing device and introduced into the exhaust gas treatment device. Harmful gases are, for example, fluorine compounds such as CF4, C2F6, SF6, NF3, ClF3, and HF, halogen compounds such as HBr and Cl2, nitrogen compounds such as NH3 and NOx, or silane compounds such as SiH4, DCS (dichlorosilane), and TEOS (tetraethyl orthosilicate).

[0017] The exhaust gas treatment device 100 shown in FIG. 1 includes a main body 1 having a flow path 1a through which a liquid flows, a liquid supply line 10 connected to the main body 1 and supplying liquid to the flow path 1a, an exhaust gas supply line 2 connected to the main body 1 and supplying exhaust gas to the flow path 1a through which the liquid flows, an aspirator 3 that draws exhaust gas from the exhaust gas supply line 2 into the flow path 1a, a low-temperature plasma generator 5 that generates low-temperature plasma in the flow path 1a to decompose harmful gases, and an exhaust line 7 that discharges exhaust gas that has passed through the low-temperature plasma generator 5 from the main body 1. The liquid is supplied to the flow path 1a of the main body 1 through the liquid supply line 10. The type of liquid supplied to the flow path 1a is appropriately selected depending on the harmful gas in the exhaust gas that is sucked into the flow path 1a from the exhaust gas supply line 2. Examples of the liquid include pure water, ultrapure water, and ion-exchanged water. In one embodiment, the liquid may be an electrolyte or alcohol. In this embodiment, the exhaust line 7 discharges not only the exhaust gas after treatment but also the liquid.

[0018] The main body 1 shown in FIG. 1 has a cylindrical shape extending in the vertical direction, and the flow path 1a also extends in the vertical direction within the main body 1. In this embodiment, the suction device 3 is disposed in the main body 1 and is an ejector that uses the liquid flowing through the flow path 1a as a driving fluid. The exhaust gas supply line 2 is connected to the main body 1 via the suction device 3. In the suction device 3, which is an ejector, the exhaust gas flowing through the exhaust gas supply line 2 is treated as the suction gas of the suction device 3. That is, by flowing liquid through the suction device 3, the exhaust gas is sucked into the flow path 1a of the main body 1 through the exhaust gas supply line 2 and mixed with the liquid in the suction device 3. At this time, the exhaust gas becomes bubbles and is mixed with the liquid, and the liquid containing the exhaust gas bubbles is discharged from the suction device 3 to the flow path 1a. In this embodiment, the atmosphere of the flow path 1a, which is the internal space of the main body 1, is maintained at atmospheric pressure or subatmospheric pressure.

[0019] 1 shows two exhaust gas supply lines 2, the number of exhaust gas supply lines 2 may be appropriately determined depending on the exhaust gas suction capacity of the suction device 3 and the harmful gas treatment capacity (decomposition capacity) of the low-temperature plasma generator 5. In other words, the exhaust gas treatment device 100 includes at least one exhaust gas supply line 2.

[0020] The low-temperature plasma generator 5 is provided in the main body 1 downstream of the suction device 3 in the flow direction of the liquid flowing through the flow path 1a, and generates low-temperature plasma in the exhaust gas in the liquid flowing through the flow path 1a. FIG. 2 is a schematic diagram showing a low-temperature plasma generating unit according to one embodiment. The low-temperature plasma generator 5 shown in FIG. 2 includes a high-voltage power supply device 11, and a first electrode 14 and a second electrode 15 arranged in the liquid flowing through the flow path 1a. The first electrode 14 and the second electrode 15 are each connected to the high-voltage power supply device 11. By operating the high-voltage power supply device 11, low-temperature plasma is generated in the exhaust gas in the liquid flowing between the first electrode 14 and the second electrode 15.

[0021] Low-temperature plasma generally refers to a so-called "weakly ionized plasma" in which the electron mean free path is long due to the low density of electrons or neutral particles in the plasma, and the electrons have high energy of 1 to 10 eV (corresponding to 10,000 to 100,000 K), while the neutral particles remain at about room temperature. The discharge phenomenon generated between the first electrode 14 and the second electrode 15 by the high-voltage power supply device 11 for generating such low-temperature plasma in the liquid is, for example, a glow discharge.

[0022] In order to generate a discharge phenomenon between the first electrode 14 and the second electrode 15, the high-voltage power supply device 11 includes a high-voltage power supply 12 that applies a voltage having a pulse waveform to the first electrode 14 and the second electrode 15. Examples of the high-voltage power supply 12 include a DC power supply, an AC power supply, a bipolar power supply, a unipolar power supply, a pulse power supply, or a high-frequency power supply. Depending on the type of the high-voltage power supply 12, the high-voltage power supply device 11 may include a pulse generator (not shown).

[0023] As shown by the virtual lines (dotted lines) in Fig. 2, the low-temperature plasma generator 5 may have multiple pairs (three pairs in Fig. 2) of first electrodes 14 and second electrodes 15. In the example shown in Fig. 2, the high-voltage power supply 12 supplies a pulse voltage to all or any pairs of the first electrodes 14 and second electrodes 15. Although not shown, the low-temperature plasma generator 5 may include multiple high-voltage power supplies 12 that supply a pulse voltage to each pair of the first electrodes 14 and second electrodes 15.

[0024] The low-temperature plasma generator 5 generates low-temperature plasma in the exhaust gas in the liquid flowing through the flow path 1a, and the harmful gas in the exhaust gas is decomposed by this low-temperature plasma. In this embodiment, the main body 1 functions as a reactor for decomposing the harmful gas in the liquid flowing through the flow path 1a formed therein by low-temperature plasma. Since the harmful gas is decomposed by the low-temperature plasma generated in the liquid, the exhaust gas after treatment is immediately cooled by the liquid. Therefore, cooling equipment (e.g., a water wall or a scrubber) required in conventional exhaust gas treatment devices is not required, and the exhaust gas treatment device can be made smaller in size. Furthermore, by-products such as dust and corrosive gas generated by decomposing the harmful gas are also immediately discharged from the main body 1 together with the liquid flowing through the flow path 1a. For example, acid gas such as hydrofluoric acid generated by decomposing the harmful gas is immediately dissolved in the liquid, diluted, and discharged to the discharge line 7. Therefore, corrosion damage to the components of the exhaust gas treatment device 100 and adhesion of dust are suppressed. Furthermore, the plasma for decomposing harmful gases is itself at a low temperature, and the first electrode 14 and the second electrode 15 are cooled by the flowing water flowing through the flow path 1a. Therefore, wear of the electrodes 14, 15 due to thermal dissolution and corrosion is suppressed, and the running costs of the exhaust gas treatment device 100 can be reduced.

[0025] In one embodiment, a part or all of the outer surface of the first electrode 14 and / or the second electrode 15 may be covered with a dielectric. The dielectric can protect the first electrode 14 and / or the second electrode 15 from harmful gases contained in the exhaust gas and by-products generated by decomposition of the harmful gases. Furthermore, the dielectric prevents direct contact between the conductor part of the first electrode 14 and / or the second electrode 15 and the plasma, thereby suppressing localized wear of the first electrode 14 and / or the second electrode 15.

[0026] FIG. 3 is a schematic diagram showing a low-temperature plasma generator according to another embodiment. The low-temperature plasma generator 5 shown in FIG. 3 includes a microwave generator 17 capable of radiating microwaves, a waveguide (waveguide section) 18 for propagating the microwaves radiated from the microwave generator 17, a matching section (isolator) 19 arranged in the waveguide 18 for adjusting the impedance of the microwaves, and a slot antenna 20 for concentrating the electric field due to the microwaves in the waveguide 18. The slot antenna 20 is arranged in the flow path 1a of the main body 1. In this embodiment, electronic vibrations are generated by the microwaves concentrated on the surface of the slot antenna 20, and low-temperature plasma is generated in the exhaust gas (bubbles) flowing through the flow path 1a. Harmful gases in the exhaust gas are decomposed by the low-temperature plasma.

[0027] As shown in Fig. 3, the low-temperature plasma generator 5 may include a bubble generating mechanism 40 that generates bubbles in the flow path 1a of the main body 1. The bubble generating mechanism 40 shown in Fig. 3 includes a bubble line 41 that communicates with the flow path 1a of the main body 1 and supplies gas in the form of bubbles to the flow path 1a, and a bubble generator 42 arranged in the bubble line 41. Examples of the bubble generator 42 include a microbubble generator and an ultrasonic vibrator. Exhaust gas is supplied to the bubble line 41, and the exhaust gas is supplied to the flow path 1a of the main body 1 via the bubble line 41.

[0028] Fig. 4 is a schematic diagram showing an example of a circulation mechanism disposed in the main body. The circulation mechanism is a mechanism for increasing the time that the liquid and exhaust gas remain in the low-temperature plasma generator 5 by reversing a part of the liquid flowing through the flow path 1a in order to efficiently decompose harmful gases contained in the exhaust gas.

[0029] The circulation mechanism 25 shown in FIG. 4 includes a first tapered tube 26 connected to the wall surface of the flow path 1a of the main body 1, and a second tapered tube 27 arranged upstream of the first tapered tube 26 in the flow direction of the liquid flowing through the flow path 1a. The first tapered tube 26 has a conical shape with an opening in the center, and the end of the first tapered tube 26 is connected to the wall surface of the flow path 1a without leaving a gap. The end of the first tapered tube 26 is the part having the maximum diameter of the first tapered tube 26. On the other hand, the second tapered tube 27 also has a conical shape with an opening in the center, and the end of the second tapered tube 27 is arranged with a gap from the wall surface of the flow path 1a. In this embodiment, the second tapered tube 27 is connected to the main body 1 by a support not shown, and the first tapered tube 26 and the second tapered tube 27 are arranged concentrically when viewed in a vertical cross section of the flow path 1a.

[0030] When the liquid and exhaust gas pass through the second tapered tube 27, the liquid and exhaust gas are divided into a first flow F1 that passes through the outer surface of the second tapered tube 27 toward the wall surface of the flow path 1a, and a second flow F2 that passes through the central opening of the second tapered tube 27 and flows through the center of the flow path 1a. The first flow F1 is prevented from flowing through the flow path 1a as it is by the first tapered tube 26, and flows back through the flow path 1a along the outer surface (upper surface) of the first tapered tube 26. As a result, the first flow F1 merges with the second flow F2 that flows through the center of the flow path 1a, and blocks the second flow F2. In this embodiment, the plasma generator 5 is configured to generate low-temperature plasma at the junction of the first flow F1 and the second flow F2. Specifically, the first electrode 14 and the second electrode 15 extend through the wall surface of the second tapered tube 27, and the low-temperature plasma is generated inside the second tapered tube 27. Such a circulation mechanism 25 can increase the time that the exhaust gas remains around the first electrode 14 and the second electrode 15, which convert the exhaust gas into low-temperature plasma, thereby efficiently decomposing harmful gases in the exhaust gas.

[0031] As shown in FIG. 4, a circulation mechanism 25 may be provided according to the number of pairs of the first electrodes 14 and the second electrodes 15 that the low-temperature plasma generator 5 has.

[0032] 5 is a schematic diagram of an exhaust gas treatment device according to another embodiment. The configuration of this embodiment that is not specifically described is similar to the above-described embodiment, and therefore a duplicated description will be omitted.

[0033] The exhaust gas treatment device 200 shown in Fig. 5 has a main body 1 configured as a tank equipped with an overflow weir 1b. The internal space of the main body 1 is divided by the overflow weir 1b into a treatment section 1c in which a low-temperature plasma generator 5 is disposed, and a discharge section 1d to which a discharge line 7 is connected. In this embodiment, the overflow weir 1b is a plate extending upward from the upper surface of the bottom wall of the main body 1, and a gap is formed between the upper end of the overflow weir 1b and the lower surface of the upper wall of the main body 1. The liquid flow path 1a formed in the main body 1 is the entire internal space of the main body 1 including the treatment section 1c and the discharge section 1d.

[0034] The liquid supply line 10 passes through the upper part of the main body 1 (the upper wall in this embodiment) and extends to the processing section 1c. The tip of the liquid supply line 10 from which the liquid is discharged is located at a position lower than the upper end of the overflow weir 1b. The liquid is supplied to the processing section 1c of the main body 1 from the upper part of the main body 1. The liquid supplied to the processing section 1c of the main body 1 is stored in the processing section 1c until the liquid level exceeds the overflow weir 1b, and then flows out over the overflow weir 1b to the discharge section 1d. The liquid that flows out to the discharge section 1d is discharged from the main body 1 via the discharge line 7. Therefore, the space above the overflow weir 1b of the main body 1 is filled with gas (atmosphere).

[0035] In the exhaust gas treatment device 200 shown in FIG. 5, the low-temperature plasma generator 5 generates low-temperature plasma in the gas in the liquid filling the treatment section 1c. More specifically, the first electrode 14 of the low-temperature plasma generator 5 is composed of a first electrode holder 14a and at least one electrode rod 14b attached to the first electrode holder 14a, and the second electrode 15 has a second electrode body 15a and a nozzle part 15b arranged on the second electrode body 15a. The nozzle part 15b is formed with at least one exhaust gas inlet 15c for supplying exhaust gas to the liquid flowing through the flow path 1a. Furthermore, the tip of the electrode rod 14b of the first electrode 14 is arranged in the treatment section 1c at a position lower than the upper end of the overflow weir 1b, and the exhaust gas inlet 15c formed in the nozzle part 15b of the second electrode 15 opens to the treatment section 1c at a position lower than the tip of the electrode rod 14b of the first electrode 14.

[0036] Furthermore, the exhaust gas supply line 2 is connected to the second electrode 15 and communicates with an exhaust gas inlet 15c formed in the nozzle portion 15b of the second electrode 15 via the second electrode body 15a of the second electrode 15.

[0037] The suction device 3 of this embodiment is connected to the upper part of the main body 1 (the upper wall in this embodiment) and includes a suction line 3a for sucking gas in the main body 1, an ejector 3b arranged in the suction line 3a, and a driving fluid line 3c for supplying a driving fluid to the ejector 3b. When a driving fluid is supplied to the ejector 3b through the driving fluid line 3c, the internal space of the main body 1, i.e., the atmosphere of the flow path 1a, becomes negative pressure through the suction line 3a. As a result, the exhaust gas is sucked into the flow path 1a formed in the main body 1 through the exhaust gas supply line 2. Although not shown, the suction device 3 may have a suction pump instead of the ejector 3b. In this case, the driving fluid line 3c is omitted.

[0038] When the suction device 3 is started, the exhaust gas is sucked into the flow path 1a from the exhaust gas inlet 15c of the second electrode 15 through the exhaust gas supply line 2, and at the same time, harmful gases in the exhaust gas are decomposed by the low-temperature plasma generated in the exhaust gas by the low-temperature plasma generator 5. The treated exhaust gas flows out together with the liquid over the overflow weir 1b to the discharge section 1d, and is discharged from the main body 1 through the suction line 3a. In this embodiment, the exhaust gas inlet 15c that introduces the exhaust gas into the flow path 1a is integrated with the second electrode 15. Therefore, all of the exhaust gas sucked into the liquid flowing through the flow path 1a comes into contact with the second electrode 15, and as a result, the proportion of the exhaust gas that is converted into low-temperature plasma increases. Therefore, the decomposition rate (treatment efficiency) of harmful gases contained in the exhaust gas can be improved.

[0039] In this embodiment, low-temperature plasma is also generated in the exhaust gas in the liquid flowing through the flow path 1a, and the harmful gas in the exhaust gas is decomposed by this low-temperature plasma. Since the harmful gas is decomposed by the low-temperature plasma generated in the liquid, the treated exhaust gas is immediately cooled by the liquid. Therefore, cooling equipment (e.g., a scrubber) required in conventional exhaust gas treatment devices is not required, and the exhaust gas treatment device can be made smaller in size. Furthermore, by-products such as dust and corrosive gas generated by decomposing the harmful gas are immediately discharged from the main body 1 together with the liquid flowing through the flow path 1a. Furthermore, the plasma itself for decomposing the harmful gas is at a low temperature, and the first electrode 14 and the second electrode 15 are cooled by the flowing water flowing through the flow path 1a. Therefore, wear of the electrodes 14 and 15 due to thermal dissolution and corrosion is suppressed, and the running cost of the exhaust gas treatment device 200 can be reduced.

[0040] As shown in FIG. 5, a control plate 9 for suppressing the flow of exhaust gas may be provided opposite the exhaust gas inlet 15c. The control plate 9 reduces the flow rate of the exhaust gas sucked from the exhaust gas inlet 15c from the treatment section 1c until it exceeds the overflow weir 1b, thereby increasing the time that the exhaust gas remains between the first electrode 14 and the second electrode 15 that convert the exhaust gas into low-temperature plasma. Therefore, the control plate 9 can increase the treatment efficiency of the exhaust gas. The control plate 9 shown in FIG. 5 has an arch shape that opens toward the second electrode 15, but the shape of the control plate 9 is not limited to this example. For example, the control plate 9 may have a bowl shape or a funnel shape. When the first electrode 14 has a single electrode rod 14b, it is preferable that the electrode rod 14b of the first electrode 14 penetrates the center of the control plate 9.

[0041] FIG. 6(a) is a perspective view showing another example of the second electrode, and FIG. 6(b) is a perspective view showing yet another example of the second electrode. FIG. 7(a) is a perspective view showing another example of the first electrode, and FIG. 7(b) is a perspective view showing yet another example of the first electrode. As shown in FIG. 6(a) and FIG. 6(b), the second electrode 15 may have a plurality of exhaust gas inlets 15c. The second electrode 15 shown in FIG. 6(a) has two exhaust gas inlets 15c. The second electrode 15 shown in FIG. 6(b) has three exhaust gas inlets 15c, which are arranged in a triangular shape as a whole. Although not shown, the number of exhaust gas inlets 15c of the second electrode 15 may be three or more. For example, a large number of exhaust gas inlets 15c may be arranged in an elliptical or triangular shape on the second electrode 15 as a whole.

[0042] The second electrode 15 shown in FIG. 6(a) corresponds to the first electrode 14 having two electrode rods 14b shown in FIG. 7(a). In this way, the second electrode 15 preferably has the same number of exhaust gas inlets 15c as the number of electrode rods 14b of the first electrode 14. In this case, the tip of the electrode rod 14b is preferably located on the central axis of the exhaust gas inlet 15c. In FIG. 6(a), each exhaust gas inlet 15c is configured as a cylindrical body extending from the upper surface of the nozzle portion 15b. The high-voltage power supply device 11 (see FIG. 5) may simultaneously apply a pulse voltage to the two electrode rods 14b to generate two low-temperature plasmas simultaneously, or may alternately apply a pulse voltage to the two electrode rods 14b to generate two low-temperature plasmas alternately at different positions.

[0043] Similarly, the second electrode 15 shown in FIG. 6(b) corresponds to the first electrode 14 having three electrode rods 14b shown in FIG. 7(b). That is, the second electrode 15 has exhaust gas inlets 15c in the same number as the number of electrode rods 14b of the first electrode 14, and the tip of each electrode rod 14b is located on the central axis of each exhaust gas inlet 15c. In FIG. 6(b), each exhaust gas inlet 15c is formed on the upper surface of the nozzle portion 15b. The high-voltage power supply device 11 (see FIG. 5) may simultaneously apply a pulse voltage to the three electrode rods 14b to generate three low-temperature plasmas simultaneously, or may alternately apply a pulse voltage to the three electrode rods 14b to generate three low-temperature plasmas at different positions alternately.

[0044] In this way, by providing the low-temperature plasma generator 5 with a first electrode 14 having a plurality of electrode rods 14b and a second electrode 15 having the same number of exhaust gas inlets 15c as the electrode rods 14b, the amount of exhaust gas that becomes low-temperature plasma can be increased, and as a result, the decomposition rate (treatment efficiency) of harmful gases contained in the exhaust gas can be improved.

[0045] Fig. 8 is a schematic diagram of an exhaust gas treatment device according to yet another embodiment. The configuration of this embodiment that is not particularly described is similar to the above-mentioned embodiment, so duplicated description will be omitted. The exhaust gas treatment device 300 shown in Fig. 8 differs from the above-mentioned embodiment in that low-temperature plasma that decomposes exhaust gas is generated in a gas atmosphere, not in a liquid.

[0046] 8 includes a reactor 6 disposed in a flow path 1a formed in a main body 1. An exhaust gas supply line 2 is connected to the reactor 6 and supplies exhaust gas into the reactor 6. In this embodiment, the exhaust gas supply line 2 extends through the wall surface of the reactor 6, and the tip of the exhaust gas supply line 2 opens into the inside of the reactor 6.

[0047] At least one outlet 6a for discharging the exhaust gas to the flow path 1a is formed in the upper wall of the reactor 6. The exhaust gas supplied from the exhaust gas supply line 2 to the internal space of the reactor 6 is discharged to the flow path 1a through the outlet 6a.

[0048] The low-temperature plasma generator 5 shown in Fig. 8 has a similar configuration to the low-temperature plasma generator 5 described with reference to Fig. 3. The tip of a waveguide (waveguide section) 18 for propagating microwaves radiated from a microwave generator 17 penetrates the main body 1 and the reactor 6 and is located inside the reactor 6.

[0049] 8, the low-temperature plasma generator 5 is a device that generates low-temperature plasma in exhaust gas by using microwaves generated by a microwave generator 17, but this embodiment is not limited to this example. For example, the low-temperature plasma generator 5 may be a device having at least a pair of a first electrode 14 and a second electrode 15. In this case, a part or the whole of the outer surface of the first electrode 14 and / or the second electrode 15 may be covered with a dielectric material.

[0050] The liquid supply line 10 and the discharge line 7 extend into the inside of the main body 1, penetrating the side wall of the main body 1. The flow rate of the liquid supplied from the liquid supply line 10 to the flow path 1a of the main body 1 and / or the flow rate of the liquid discharged from the discharge line 7 are adjusted so that the flow path 1a is not completely filled with liquid. In other words, gas (atmosphere) is present in the space above the flow path 1a.

[0051] The suction device 3 of this embodiment has a similar configuration to the suction device 3 described with reference to FIG. 5. That is, the suction device 3 is connected to the upper part of the main body 1 (the upper wall in this embodiment) and includes a suction line 3a for sucking gas in the main body 1, an ejector 3b arranged in the suction line 3a, and a driving fluid line 3c for supplying a driving fluid to the ejector 3b. When the driving fluid is supplied to the ejector 3b through the driving fluid line 3c, the internal space of the main body 1, i.e., the atmosphere of the flow path 1a, becomes negative pressure through the suction line 3a. As a result, the exhaust gas is sucked into the flow path 1a formed in the main body 1 through the reactor 6 through the exhaust gas supply line 2. The flow rate of the exhaust gas supplied from the exhaust gas supply line 2 by the suction device 3 is adjusted so that the liquid flowing through the flow path 1a does not enter the reactor 6. Although not shown, the suction device 3 may have a suction pump instead of the ejector 3b. In this case, the driving fluid line 3c is omitted.

[0052] When the suction device 3 is started, the exhaust gas is sucked into the reactor 6 through the exhaust gas supply line 2, and at the same time, it is decomposed by the low-temperature plasma generated by the low-temperature plasma generator 5. The treated exhaust gas is immediately discharged into the flow path 1a through the outlet 6a of the reactor 6, and is immediately cooled by the liquid flowing through the flow path 1a. Therefore, cooling equipment (e.g., a scrubber) required in conventional exhaust gas treatment devices is not required, and the exhaust gas treatment device can be made smaller in size. Furthermore, by-products such as dust and corrosive gases generated by decomposing the harmful gas are immediately discharged from the main body 1 together with the liquid flowing through the flow path 1a. Furthermore, since the plasma itself for decomposing the harmful gas is low temperature, wear on the reactor 6 is suppressed, and the running costs of the exhaust gas treatment device 300 can be reduced.

[0053] FIG. 9 is a diagram showing an example of an exhaust gas treatment process system in which an exhaust gas treatment device is arranged. In the exhaust gas treatment process system shown in FIG. 9, exhaust gas is discharged from a process chamber 50 of a semiconductor manufacturing device by a vacuum pump 51. An exhaust gas supply line 2 extends from the vacuum pump 51 to a main body 1 of the exhaust gas treatment device 100 (or 200 or 300). In the example shown in FIG. 9, a plurality of (four) exhaust gas treatment devices 100 (or 200 or 300) are connected to one process chamber 50, but the number of process chambers 50 and the number of exhaust gas treatment devices 100 (or 200 or 300) in the exhaust gas treatment process system are not limited to this example. For example, one exhaust gas treatment device 100 (or 200 or 300) may be connected to one process chamber 50, or one exhaust gas treatment device 100 (or 200 or 300) may be connected to multiple process chambers 50.

[0054] 9, one high-voltage power supply unit 11 is connected to four exhaust gas treatment devices 100 (or 200 or 300), but the number of high-voltage power supply units 11 in the exhaust gas treatment process system is not limited to this example. For example, one high-voltage power supply unit 11 may be connected to one exhaust gas treatment device 100 (or 200 or 300).

[0055] 9, the exhaust gas line 7 of the exhaust gas treatment device 100 (or 200 or 300) may be connected to another exhaust gas treatment device 400. Examples of the other exhaust gas treatment device 400 include a wet type exhaust gas treatment device, a combustion type exhaust gas treatment device, or a dry type exhaust gas treatment device. The wet type exhaust gas treatment device is, for example, a scrubber, and the dry type exhaust gas treatment device is, for example, an exhaust gas treatment device equipped with a treatment tank filled with an adsorbent that adsorbs harmful gases.

[0056] Although not shown, the vacuum pump 51 may be connected to an exhaust gas treatment device 400 such as a wet type exhaust gas treatment device, a combustion type exhaust gas treatment device, or a dry type exhaust gas treatment device, and the exhaust gas treatment device 100 (or 200 or 300) may be connected to the exhaust gas treatment device 400. In this case, the exhaust gas supply line 2 extends from the exhaust gas treatment device 400 to the main body 1 of the exhaust gas treatment device 100 (or 200 or 300), and the exhaust gas treated in the exhaust gas treatment device 400 is treated by the exhaust gas treatment device 100 (or 200 or 300).

[0057] Furthermore, although not shown, the exhaust gas supply line 2 may be built into the vacuum pump 51 or may be integrated with the vacuum pump 51. In these cases, the main body 1 of the exhaust gas processing device 100 (or 200 or 300) is directly connected to the vacuum pump 51.

[0058] The above-described embodiments have been described for the purpose of enabling a person having ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments are naturally possible for a person skilled in the art, and the technical idea of ​​the present invention can be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope according to the technical idea defined by the claims. [Explanation of symbols]

[0059] 1 Main unit 1a Flow path 2 Exhaust gas supply line 3 Suction device 5. Low-temperature plasma generator 6. Reactor 7 Discharge Line 9 Control Panel 10 Liquid Supply Line 11 High voltage power supply 12 High voltage power supply 14 1st electrode 14a First electrode holder 14b Electrode rod 15 2nd electrode 15a 2nd electrode body 15b Nozzle part 15c Exhaust gas inlet 17 Microwave Generator 18 Waveguide (waveguide section) 25 Circulation mechanism 26 First tapered tube 27 Second tapered tube 50 Process Chambers 51 Vacuum Pump 100,200,300,400 Exhaust gas treatment equipment

Claims

1. An exhaust gas treatment device for detoxifying harmful gases contained in exhaust gas, comprising: a main body in which a flow path for a liquid to flow is formed; an exhaust gas supply line connected to the main body for supplying the exhaust gas to the flow path through which the liquid flows; a suction device for sucking the exhaust gas from the exhaust gas supply line into the flow path; a low-temperature plasma generator for generating low-temperature plasma in the flow path to decompose the harmful gas; and an exhaust line for discharging the exhaust gas that has passed through the low-temperature plasma generator from the main body.

2. An exhaust gas treatment device for detoxifying harmful gases contained in exhaust gas, comprising: a main body in which a flow path for a liquid to flow is formed; an exhaust gas supply line connected to the main body for supplying the exhaust gas to the flow path through which the liquid flows; a suction device for sucking the exhaust gas from the exhaust gas supply line into the flow path; a low-temperature plasma generator for generating low-temperature plasma in the exhaust gas supply line to decompose the harmful gas; and an exhaust line for discharging the exhaust gas containing the harmful gas decomposed by the low-temperature plasma from the main body.

3. The suction device includes an ejector disposed in the flow path upstream of the low-temperature plasma generator when viewed in the flow direction of the liquid, wherein the driving fluid of the ejector is the liquid. The exhaust gas treatment device according to claim 1.

4. The suction device includes an ejector disposed in the exhaust line, wherein by supplying a driving fluid to the ejector, the internal space of the main body is decompressed to suck the exhaust gas from the exhaust gas supply line into the main body. The exhaust gas treatment device according to claim 1.

5. The exhaust gas treatment device further comprises a circulation mechanism for causing a part of the liquid flowing through the flow path and the exhaust gas to flow in a reverse direction to increase the time that the liquid and the exhaust gas stay in the low-temperature plasma generator, wherein the circulation mechanism includes: a first tapered tube connected to the wall surface of the flow path and having a reduced diameter toward the upstream side in the flow direction of the liquid; a second tapered tube disposed with a gap from the flow path upstream of the first tapered tube when viewed in the flow direction of the liquid, and dividing the liquid and the exhaust gas into a first flow toward the wall surface of the flow path and a second flow flowing through the center of the flow path; wherein the first tapered tube causes the first flow to flow in a reverse direction through the flow path toward the second flow. The exhaust gas treatment device according to claim 3.

6. The plasma generator includes: a high-voltage power supply device; at least a pair of first electrodes and second electrodes disposed in the flow path, The exhaust gas treatment device according to claim 3 or 4, wherein a low-temperature plasma is generated between the first electrode and the second electrode by the high-voltage power supply device.

7. The plasma generation device includes a microwave generation device capable of emitting microwaves, a waveguide section for propagating the microwaves, a matching section for adjusting the impedance of the microwaves disposed in the waveguide section, a slot antenna for concentrating the electric field by the microwaves, The exhaust gas treatment device according to claim 3 or 4, wherein exhaust gas in the liquid is converted into low-temperature plasma on the surface of the slot antenna.

8. The exhaust gas treatment device according to claim 6, wherein a part or all of the outer surface of the first electrode and / or the second electrode is covered with a dielectric.

9. The harmful gas is a fluorine compound, a nitrogen compound, or a silane-based compound, The liquid is pure water, ultrapure water, ion-exchanged water, or an electrolytic solution. The exhaust gas treatment device according to claim 1 or 2.

10. During the treatment of the exhaust gas, the atmosphere in the internal space of the main body is maintained at atmospheric pressure or near atmospheric pressure. The exhaust gas treatment device according to claim 1 or 2.

11. The exhaust gas supply line extends from a vacuum pump connected to a process chamber of a semiconductor manufacturing apparatus to the main body, or extends from an exhaust gas treatment device connected to the vacuum pump to the main body. The exhaust gas treatment device according to claim 1 or 2.

12. The exhaust gas supply line is incorporated in or integrated with a vacuum pump connected to a process chamber of a semiconductor manufacturing apparatus, The main body is directly connected to the vacuum pump. The exhaust gas treatment device according to claim 1 or 2.

13. The discharge line extends from the main body to a wet exhaust gas treatment device, a combustion type exhaust gas treatment device, or a dry exhaust gas treatment device. The exhaust gas treatment device according to claim 11.

14. At least one exhaust gas inlet for introducing the exhaust gas into the liquid is formed in the second electrode, The exhaust gas supply line is connected to the second electrode in which the exhaust gas inlet is formed. The exhaust gas treatment device according to claim 6.

15. The plasma generation device includes a plurality of pairs of first electrodes and second electrodes, or a first electrode having a plurality of electrode rods and a second electrode. The exhaust gas treatment device according to claim 6.

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