JP2011189228A - Exhaust gas treatment system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide technique for miniaturizing a system which treats an exhaust gas discharged from a semiconductor manufacturing device. <P>SOLUTION: This exhaust gas treatment system 100 treats a mixed gas containing at least hydrogen and a monosilane discharged from the semiconductor manufacturing device 1. In addition, the exhaust gas treatment system 100 comprises: a pump part 2 for exhausting the mixed gas discharged from the semiconductor manufacturing device; a compressor 11 for compressing and sending to a subsequent stage the mixed gas exhausted from the pump part 2; a gas storage part 3 for collecting and storing the compressed mixed gas; a flow rate control part 4 for controlling the flow rate of the mixed gas supplied from the gas storage part 3; and a membrane separation part 6 for selectively making hydrogen permeate and separating the monosilane and hydrogen from the mixed gas. Thus, it is possible to mitigate the pressure fluctuation of the mixed gas discharged from the semiconductor manufacturing device 1 and stably operate the exhaust gas treatment system. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an exhaust gas treatment system for treating a gas containing hydrogen and silane gas discharged from a semiconductor manufacturing apparatus.

  Exhaust gas discharged from semiconductor manufacturing equipment, particularly plasma CVD equipment for forming thin film silicon used in solar cells, includes monosilane that requires detoxification, hydrogen that does not require detoxification, and fine particles (higher order Silane) is mixed. In a conventional exhaust gas treatment apparatus, after removing fine particles with a filter, nitrogen is added to a mixed gas containing monosilane and hydrogen (hydrogen / monosilane = 2 to 100), and then the treatment is performed using an abatement apparatus. ing. The amount of nitrogen added is adjusted so that the monosilane concentration is 2% or less from the viewpoint of powder generation.

Japanese Patent Laid-Open No. 62-134414 Japanese Patent Laid-Open No. 9-239239

  In conventional exhaust gas treatment equipment, detoxification was performed on a mixed gas containing a small amount of monosilane that requires detoxification and a large amount of hydrogen that does not require detoxification. This led to an increase in the scale of exhaust gas treatment equipment. Further, when monosilane is detoxified by combustion, the consumption of LPG gas for combustion is increased and energy efficiency is reduced. Furthermore, since the pressure and flow rate of the exhaust gas discharged from the semiconductor manufacturing apparatus varies significantly depending on the operating conditions of the semiconductor manufacturing apparatus, it has been difficult to stably operate the exhaust gas processing apparatus.

  This invention is made | formed in view of such a subject, The objective is to provide the technique which miniaturizes the system which processes the waste gas discharged | emitted from a semiconductor manufacturing apparatus.

  In order to solve the above problems, an exhaust gas treatment system according to an aspect of the present invention treats a mixed gas containing at least hydrogen and monosilane discharged from a semiconductor manufacturing apparatus. This exhaust gas treatment system includes a pump that exhausts the mixed gas discharged from the semiconductor manufacturing apparatus, a compressor that compresses the mixed gas exhausted by the pump and sends it to the subsequent stage, and a gas that collects and stores the compressed mixed gas A storage unit, a flow rate control unit that controls the flow rate of the mixed gas supplied from the gas storage unit, and a membrane separation unit that selectively permeates hydrogen and separates monosilane and hydrogen from the mixed gas.

  According to this aspect, the mixed gas containing at least hydrogen and monosilane discharged from the semiconductor manufacturing apparatus is separated into monosilane that requires detoxification and hydrogen that does not need to be detoxified at the membrane separation unit, and hydrogen after separation. And monosilane, the scale of the treatment facility can be reduced, and the exhaust gas treatment system can be made compact.

  ADVANTAGE OF THE INVENTION According to this invention, the system which processes the waste gas discharged | emitted from a semiconductor manufacturing apparatus can be reduced in size.

It is a systematic diagram showing an example of the outline of the exhaust gas treatment system concerning this embodiment. It is the systematic diagram which showed the structure of the exhaust gas processing system which concerns on this Embodiment in detail. It is the systematic diagram which showed an example of the data processing in each part of the exhaust gas processing system which concerns on this Embodiment. It is the systematic diagram which showed the structure of the exhaust gas processing system which concerns on an Example. Except that the pressure was adjusted to 50 kPaG by the non-permeate side back pressure valve, the exhaust gas treatment system was operated by satisfying the equation (2) (C ₁ = 0.5) using the conditions of Example 2 as initial conditions. It is the figure which showed the result of having monitored the change of the hydrogen recovery rate with respect to years of use (converted value). The result of monitoring the change of the hydrogen recovery rate with respect to the years of use (converted value) when the exhaust gas treatment system is operated by satisfying the formula (3) (C ₂ = 1.0) with the conditions of Example 1 as initial conditions It is a figure. The initial condition is the same as in Example 1 except that a membrane separation module with a membrane separation capacity of 3.0 L is used, and nitrogen is added at 30 NL / min in the third component gas addition section. Te (C 3 ₌ 1.0) is a diagram showing the results of monitoring changes in the hydrogen recovery rate for age (converted value) at the time of driving. It is the systematic diagram which showed the structure of the exhaust gas processing system which concerns on a comparative example. As a result of monitoring the change in the hydrogen recovery rate with respect to the service life (converted value) when the exhaust gas treatment system was operated without satisfying the formula (2) (C ₁ = 0.1) with the conditions of Example 1 as the initial conditions FIG. As a result of monitoring the change in the hydrogen recovery rate with respect to the service life (converted value) when the exhaust gas treatment system was operated without satisfying the formula (3) (C ₂ = 0.25) with the conditions of Example 2 as the initial conditions FIG. The initial conditions were the same as in Example 1 except that a membrane separation module with a membrane separation capacity of 3.0 L was used, and the exhaust gas treatment system was operated without satisfying the formula (4) (C ₃ = 0.2). It is the figure which showed the result of having monitored the change of the hydrogen recovery rate with respect to years of use (converted value).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

  FIG. 1 is a system diagram showing an example of an outline of an exhaust gas treatment system according to the present embodiment. FIG. 2 is a system diagram showing in more detail the configuration of the exhaust gas treatment system according to the present embodiment. FIG. 3 is a system diagram showing an example of data processing in each part of the exhaust gas treatment system according to the present embodiment.

  As shown in FIG. 1, an exhaust gas treatment system 100 according to the present embodiment collects and compresses a mixed gas containing at least hydrogen and monosilane discharged from a plurality of semiconductor manufacturing apparatuses 1 through a pump unit 2; , A gas storage unit 3 for storing the mixed gas discharged from the compressor 11, a flow rate control unit 4 for controlling the flow rate of the mixed gas from the gas storage unit 3, and a membrane separation unit for separating monosilane and hydrogen from the mixed gas 6, a hydrogen gas processing unit 7 that processes the hydrogen separated by the membrane separation unit 6, and a silane gas processing unit 8 that processes the silane gas separated by the membrane separation unit 6.

  Although it does not specifically limit as the semiconductor manufacturing apparatus 1, The plasma CVD apparatus etc. for forming the thin film silicon used for a solar cell are mentioned.

The composition of the mixed gas discharged from the semiconductor manufacturing apparatus 1 is not particularly limited, and includes, for example, monosilane that needs to be removed, hydrogen, nitrogen, and trace impurities that do not need to be removed. Examples of the trace impurities include higher order silanes containing a plurality of Si such as disilane and trisilane, PH ₃ and B ₂ H ₆ (each 0.001 to 1%).

  The pump unit 2 sucks the mixed gas discharged from the semiconductor manufacturing apparatus 1 and sends it to the subsequent compressor 11. The type of pump used is not particularly limited, but a dry pump is often used in a semiconductor manufacturing apparatus. A purge gas can be introduced into the dry pump for the purpose of maintaining airtightness, preventing unnecessary deposits, preventing corrosion inside the pump, and improving exhaust capability. The purge gas is not particularly limited, but an inert gas such as nitrogen or argon is mainly used. The amount of purge gas introduced is not particularly limited, but is generally about 10 to 50 NL / min per pump.

  Further, as shown in FIG. 2, a filter 2a may be provided in the front stage or / and the rear stage of the pump 2b. In particular, when the exhaust gas contains a relatively large amount of fine particles such as higher-order silane, it is preferable to provide the filter 2a. The filter 2a is a particulate trapping filter that selectively removes particulates such as higher order silane contained in the mixed gas. Although it does not specifically limit as a filter to be used, Filters, such as a spiral type, can be used.

Furthermore, in the semiconductor manufacturing apparatus 1, chemical cleaning may be performed in order to remove deposits in the chamber due to film formation. In chemical cleaning, plasma treatment is generally performed under the introduction of a gas such as NF ₃ or F ₂ in order to remove the silicon thin film deposited in the chamber. However, since these gases are flammable, contact with combustible gases such as hydrogen and monosilane must be avoided, and it is preferable to install a switching valve 2c after the pump 2b as shown in FIG. . As a result, when exhaust gas for chemical cleaning comes out, switching to the combustion-supporting gas treatment system prevents such exhaust gas from entering the silane-based gas treatment line. The switching valve 2c may have its mechanism built in the pump itself.

  Although it does not specifically limit as the compressor 11, A diaphragm compressor, a centrifugal compressor, an axial flow compressor, a reciprocating compressor, a twin screw compressor, a single screw compressor, a scroll compressor, a rotary compressor, etc. are mention | raise | lifted. However, among them, a diaphragm type compressor is more preferable.

  Although it does not specifically limit as an operating condition of the compressor 11, It is preferable to drive | operate so that the temperature of the mixed gas after compression may be 200 degrees C or less which is the decomposition temperature of monosilane. That is, considering that the mixed gas discharged from the pump unit 2 is compressed from normal pressure, it is desirable to operate the compressor at a compression ratio of 4.4 or less.

  The configuration of the compressor used in the compressor 11 is not particularly limited, but a configuration in which an inverter is provided to stably operate the compressor even when the flow rate of the mixed gas supplied to the compressor varies. Alternatively, it is preferable to have a spillback configuration in which the mixed gas once compressed by the compressor is returned to the suction side of the compressor.

  The gas storage unit 3 collects the mixed gas discharged from the plurality of semiconductor manufacturing apparatuses 1 through the pump unit 2 in a tank or the like having a sufficient capacity so that the flow rate and pressure of the mixed gas discharged from each semiconductor manufacturing apparatus 1 This is to average the fluctuations and to circulate a mixed gas having a constant flow rate and pressure through the membrane separation unit 6 at all times. Further, by devising the structure, it is possible to provide a function of removing fine particles contained in the mixed gas.

  Although the size of the tank used for the gas storage unit 3 is not particularly limited, it is desirable that the tank be equal to or larger than the total value of the maximum flow rates of the gas supplied to each semiconductor manufacturing apparatus 1.

  Although the pressure in the tank used for the gas accommodating part 3 is not specifically limited, It is desirable to set it as 1 MPaG at the maximum.

  Further, at the start of operation of the apparatus, it is preferable that the purge gas or exhaust gas of the pump is supplied from the compressor 11 to the gas storage unit 3 and accumulated in the gas storage unit 3 with the outlet valve of the gas storage unit 3 closed. As a result, even when the exhaust gas flow rate of the semiconductor manufacturing apparatus greatly fluctuates, it is possible to maintain a sufficient pressure to keep the supply flow rate to the separation device constant, and the gas that can be stored in the gas storage unit 3 Since the amount can be increased, the volume of the gas storage portion can be reduced. Furthermore, if a sufficient pressure is accumulated, the non-permeate side pressure of the membrane separation device can be set high, so that a sufficient differential pressure from the permeate side can be obtained, which is advantageous in operation.

  The flow rate control unit 4 is for controlling the flow rate and pressure of the mixed gas collected in the gas storage unit 3 to be constant. Although it does not specifically limit regarding the control method, What is not influenced by the pressure fluctuation of the mixed gas supplied to the flow volume control part 4 is desirable, For example, a mass flow controller etc. are mentioned. Further, regarding the pressure, the necessary pressure can be secured by selecting the operating condition of the compressor 11.

  The membrane separation unit 6 includes at least a membrane separation device 6b shown in FIG. 2, a permeation side pressure control unit 6c, and / or a non-permeation side pressure control unit 6d. The membrane separation device 6b is a membrane that selectively permeates hydrogen and is not particularly limited as long as it does not contain a metal component that reacts with monosilane, for example, palladium, nickel, etc. as a main component. Etc. Examples of the semipermeable membrane include a dense layer that selectively transmits hydrogen and a porous base material that supports the dense layer. Examples of the shape of the semipermeable membrane include a flat membrane, a spiral membrane, and a hollow fiber membrane. Among these, a hollow fiber membrane is more preferable.

  Materials used for the dense layer include polyimide, polysiloxane, polysilazane, acrylonitrile, polyester, cellulose polymer, polysulfone, polyalkylene glycol, polyethylene, polybutadiene, polystyrene, polyvinyl halide, polyvinylidene halide, polycarbonate, and any of these A block copolymer having a repeating unit may be mentioned.

  Examples of the material used for the substrate include inorganic materials such as glass, ceramic and sintered metal, and porous organic materials. Examples of the porous organic material include polyether, polyacrylonitrile, polyether, poly (arylene oxide), polyether ketone, polysulfide, polyethylene, polypropylene, polybutene, and polyvinyl.

  The flow rate, pressure, temperature, monosilane gas concentration, and non-permeate side pressure and permeate side pressure of the membrane separator 6b supplied to the membrane separator 6b are not particularly limited. For example, the flow rate may be a membrane separator. 5 NL / min to 500 NL / min, preferably 10 NL / min to 100 NL / min, preferably −90 kPaG to 1.0 MPaG, and temperature −20 ° C. to 100 Desirably, the monosilane gas concentration is 30 vol% or less, preferably 20 vol% or less, more preferably 10 vol% or less, and the non-permeation side pressure of the membrane separation device 6 b is −90 kPaG to 0.85 MPaG, permeation The side pressure is preferably −100 kPaG to 0.9 MPaG.

  Here, the capacity | capacitance of a membrane separator shows the volume of the part with which the separation membrane in a membrane separator was fully packed.

  Further, when operating at a temperature other than room temperature as the temperature of the mixed gas supplied to the membrane separation device 6b described above, it is necessary to provide a temperature control unit 6a as shown in FIG.

  The temperature controller 6a is not particularly limited as long as it has a function of cooling or heating the mixed gas, and examples thereof include an electric heater and various heat exchangers. The mixed gas cooled or heated by the temperature controller 6a is supplied to the membrane separation device 6b.

  The membrane separation conditions described above are actually intertwined. For example, in the case of a membrane separation capacity of 1 L, the flow rate supplied to the membrane separation apparatus is 20 NL / min to 50 NL / min, and the monosilane gas concentration is 10 vol% or less, the temperature is 10 ° C. to 40 ° C., the non-permeation side pressure of the membrane separator is preferably atmospheric pressure or higher, and the permeation side pressure is preferably −100 kPaG to −60 kPaG.

  The gases separated by the membrane separation device 6b are sent to the hydrogen gas processing unit 7 and the silane gas processing unit 8, respectively. In the hydrogen gas processing unit 7, simply use the recovered hydrogen as a combustion process or fuel, or, for example, as shown in FIG. 2, after diluting below the explosion limit with nitrogen or air in the dilution unit 7 b, You may comprise so that it may discharge | release outside. In this dilution, it is preferable from the viewpoint of safety to dilute the hydrogen concentration to below the lower explosion limit (4 vol% or less). The dilution ratio in the dilution section 7b is not particularly limited as long as it satisfies at least the monosilane concentration of 5 ppmv or less. However, if the dilution ratio is controlled based on the measurement result of the permeate side gas analysis section 6e, it can be efficiently controlled without waste. Can do. The separation gas diluted by the dilution unit 7b is discharged to the outside by the blower 7c. Further, in order to reduce the concentration of monosilane in the recovered gas, a mechanism capable of selectively detoxifying monosilane may be added (not shown). The detoxifying agent for selectively detoxifying is not particularly limited, and examples thereof include an oxidizing agent and an adsorbent. Further, as shown in FIG. 4, a hydrogen gas purification unit 7a may be installed so that hydrogen can be purified and reused.

  In the silane gas processing unit 8, for example, as shown in FIG. 2, monosilane, which is a toxic gas, is diluted to a predetermined concentration by the dilution unit 8b in accordance with the device specifications of the detoxifying unit 8c, which is a detoxifying device. After that, it is detoxified below the allowable concentration of monosilane by being introduced into the abatement part 8c, and discharged to the outside by the blower 8d. A silane gas purification unit 8a may be installed so that monosilane can be purified and reused.

  In the exhaust gas treatment system according to the present embodiment, various incidental facilities as shown in FIGS. 2 and 3 can be added.

  For example, as shown in FIG. 2, the gas analyzer 5 is installed to measure the concentration of the component gas of the mixed gas controlled at a constant flow rate by the flow rate controller 4, particularly the concentration of hydrogen and monosilane in the gas. Can do. In the gas analyzer 5, the method is not particularly limited as long as at least the hydrogen concentration and the monosilane concentration in the mixed gas can be measured. For example, FT-IR equipped with a gas flow type sample cell or an on-line type gas chromatograph And graphs.

  Also, as shown in FIG. 2 and FIG. 3, a third component gas addition unit 10 is provided before and after the gas analysis unit 5 to adjust the monosilane concentration in the mixed gas, and the third component gas is A certain amount may be added to the mixed gas. The third component gas to be added is not particularly limited as long as it does not react rapidly with the component gas in the mixed gas such as monosilane, but for example, nitrogen, argon, hydrogen, helium, xenon, carbon number 1 to 4 Examples include hydrocarbon gas. When the third component gas addition unit 10 is provided, it is preferable to provide the gas analysis unit 5 before and after the third component gas addition unit 10 to measure the hydrogen concentration and monosilane concentration in the mixed gas before and after the addition of the third component gas.

  Further, as shown in FIG. 2, in order to measure the flow rate and the component concentration of each gas separated by the membrane separation unit 6, a permeation side gas analysis unit 6e and a non-permeation side gas analysis unit 6f can be provided. . For example, the hydrogen gas processing unit 7 measures the flow rate of the permeate side gas of the membrane separation device 6b, the hydrogen concentration in the gas, and the monosilane concentration, thereby diluting the recovered hydrogen gas in the dilution unit 7b when released to the atmosphere. The rate can be controlled based on the measurement result so that the monosilane concentration becomes an allowable concentration (5 ppmv or less). In the diluting part 7b, in order to safely release the recovered hydrogen into the atmosphere, nitrogen, air, or the like can be added to make the monosilane concentration below the allowable concentration and the hydrogen concentration below the lower explosion limit (4 vol% or less).

  The permeate side gas discharged from the permeate side of the membrane separation device 6b is measured by the permeate side gas analyzer 6e for the flow rate, the hydrogen concentration, and the monosilane concentration. The permeate side pressure controller 6c is for controlling the permeate side pressure of the membrane separation device 6b. It is also possible to calculate the hydrogen gas recovery rate (hydrogen recovery rate) by combining the obtained measurement results with the measurement results of the flow rate of the mixed gas supplied to the membrane separation device 6b and the hydrogen concentration and monosilane concentration. it can. Here, the hydrogen recovery rate is defined as the following formula (1).

Hydrogen recovery rate (%) = 100 × ((A / 100) × B)) / ((C / 100) × D) (1)
Here, A is the hydrogen concentration of the permeate side gas (permeate side hydrogen concentration) (vol%), B is the permeate side gas flow rate (permeate side gas total flow rate) (L / min), and C is supplied to the membrane separator. Hydrogen concentration of the mixed gas (supply side hydrogen concentration) (vol%), D represents the flow rate of the mixed gas supplied to the membrane separator (total flow rate of supply side gas) (L / min).

  By monitoring this hydrogen recovery rate, it is possible to grasp the deterioration state of the membrane separation device 6b. For example, by controlling the temperature of the mixed gas supplied to the membrane separation device 6b, the non-permeation side pressure, the permeation side pressure, and the addition amount of the third component gas as the hydrogen recovery rate decreases, Operation that always maintains a high hydrogen recovery rate becomes possible. At this time, the temperature of the mixed gas supplied to the membrane separation device 6b and the permeate side of the membrane separation device 6b so as to satisfy the following formulas (2) to (4) with respect to the decrease rate of the hydrogen recovery rate It is preferable to control the pressure and the amount of the third component gas added.

ΔP = C ₁ × ΔA, C ₁ ≧ 0.5 (2)
Here, ΔP represents a decrease in pressure on the permeate side (kPa), and ΔA represents a decrease in hydrogen recovery rate (%).

ΔT = C ₂ × ΔA, C ₂ ≧ 0.8 (3)
Here, ΔT represents the temperature increase (° C.), and ΔA represents the decrease (%) in the hydrogen recovery rate.

ΔF = C ₃ × ΔA, C ₃ ≧ 0.3 (4)
Here, ΔF represents a decrease (L / min) in the third component gas addition amount, and ΔA represents a decrease (%) in the hydrogen recovery rate.

  Further, for example, in the silane gas processing unit 8, when the flow rate of the non-permeate side gas of the membrane separation device 6b and the hydrogen concentration and monosilane concentration in the gas are measured, the recovered monosilane gas is rendered harmless by the abatement unit 8c. Based on the measurement result, the dilution rate in the dilution section 8b can be controlled so that the monosilane concentration is less than or equal to the allowable concentration (for example, about 2 vol%) of the abatement apparatus.

  The above-described control is executed using the arithmetic control unit 30 shown in FIG. The arithmetic control unit 30 controls the flow rate of the mixed gas by the flow rate control unit 4 based on the flow rate of the mixed gas to be controlled, the measurement result of the monosilane concentration in the mixed gas in the gas analysis unit 5 and the capacity of the membrane separation device. can do.

  Further, the arithmetic control unit 30 is configured to measure the mixed gas flow rate value in the flow rate control unit 4, the measurement result of the monosilane concentration in the mixed gas in the gas analysis unit 5, the permeation side gas flow rate and the permeation side in the permeation side gas analysis unit 6e. Based on the measurement result of monosilane concentration measurement in the gas, the hydrogen recovery rate can be calculated.

  In the arithmetic control unit 30, the temperature of the mixed gas supplied to the membrane separation device 6b, the non-permeation side pressure, the permeation side pressure, the third component with respect to the calculated decrease rate of the hydrogen recovery rate The amount of gas added can be controlled.

  Further, the calculation control unit 30 determines the operating conditions of the hydrogen gas purification unit 7a and the recovered hydrogen based on the measurement result of the permeation side gas flow rate in the permeation side gas analysis unit 6e and the hydrogen concentration and monosilane concentration in the permeation side gas. A determination can be made as to whether to reuse the gas. If it is determined that the recovered hydrogen gas is not reused, the arithmetic control unit 30 controls the dilution rate in the dilution unit 7b of the hydrogen gas processing unit 7 so that the monosilane concentration becomes an allowable concentration (5 ppmv or less). You can also

  Furthermore, the calculation control unit 30 determines the operating conditions of the silane gas purification unit 8a based on the measurement results of the non-permeate side gas flow rate in the non-permeate side gas analyzer 6f and the hydrogen concentration and monosilane concentration in the non-permeate side gas, It can be determined whether or not the recovered monosilane is reused. When it is determined that the recovered monosilane is not reused, the arithmetic control unit 30 sets the dilution rate in the dilution unit 8b of the silane gas treatment unit 8 so that the monosilane concentration is less than the allowable concentration (for example, about 2 vol%) of the abatement apparatus. It can also be controlled to become. Further, it is preferable that a valve for switching between a line going to the abatement part 8c and a line going to the semiconductor manufacturing apparatus 1 for reuse is installed in the subsequent stage of the non-permeation side gas analysis part 6f.

  According to the above-described exhaust gas treatment system, even if the pressure and flow rate of the mixed gas discharged from the semiconductor manufacturing apparatus fluctuate, while maintaining the flow rate and pressure of the mixed gas supplied to the membrane separation unit, Stable operation is possible without applying a back pressure that affects the pump that exhausts the discharged mixed gas.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited only to these Examples.

[Example 1]
FIG. 4 is a system diagram illustrating a configuration of the exhaust gas treatment system according to the embodiment. As shown in FIG. 4, the exhaust gas treatment system according to the above-described embodiment was connected to three CVD apparatuses for manufacturing a thin film silicon solar cell, which is one of the semiconductor manufacturing apparatuses 1. The exhaust gas treatment system sucks the mixed gas discharged from the plurality of PE-CVD apparatuses 12 together with nitrogen introduced from the outside by a dry pump 13a corresponding to each apparatus, and directs the mixed gas to the compressor 26 through the filter 14. And send it out. A switching valve 33 is provided after the dry pump 13a. As a result, when exhaust gas for chemical cleaning comes out, switching to the combustion-supporting gas treatment system prevents such exhaust gas from entering the silane-based gas treatment line.

As the compressor 26, a compressor that can be operated at a compression ratio of 4 was selected. With the pressure accumulation valve 32 closed, purge nitrogen of each pump was flowed at a flow rate of 30 NL / min to increase the pressure in the airtight tank 15 (capacity: 5 m ³ ) to 0.3 MPaG. Thereafter, the pressure accumulating valve 32 was opened, gas supply to the mass flow controller 16 was started, and each PE-CVD apparatus 12 was shifted by 4 minutes to start operation. Each PE-CVD apparatus 12 was operated under the conditions shown in Table 1. The gas flow rate was controlled to 151.5 NL / min with the mass flow controller 16, and the temperature was adjusted to 40 ° C. with the heat exchanger 18, and then supplied to the membrane separation module 20 (polyimide hollow fiber membrane, capacity 2.4 L). At this time, the permeation side back pressure valve 21a was adjusted so that the pressure was −98 kPaG. Further, the non-permeate side back pressure valve 21b was adjusted so that the pressure was 0.1 MPaG. Table 2 shows the flow rate and composition of the exhaust gas before the compressor at this time. The separated permeated side gas had a SiH ₄ concentration of 0.019 vol% and a hydrogen recovery rate of 90.9%, which were constant regardless of fluctuations in the exhaust gas flow rate.

  The flow meter 22a and the analyzer 17a shown in FIG. 4 measure the flow rate in the mixed gas discharged from the PE-CVD apparatus 12, and the hydrogen concentration and monosilane concentration in the mixed gas. The mixed gas whose flow rate and pressure are controlled to a predetermined value by the mass flow controller 16 is subjected to measurement of the hydrogen concentration and monosilane concentration by the analyzer 17b, and then the temperature is controlled by the functions of the heat exchanger 18 and the circulating thermostat 19. , Flows into the membrane separation module 20. Flow meters 22b and 22c are provided at the subsequent stage of the permeable side and the non-permeable side of the membrane separation module 20, respectively.

  In the exhaust gas treatment system shown in FIG. 4, the gas on the permeate side of the membrane separation module passes through the flow meter 22b and the analyzer 17c, and the flow rate of the permeate side gas and the hydrogen concentration and monosilane concentration in the permeate side gas are measured. . The permeate gas sucked by the dry pump 13b is appropriately diluted with nitrogen based on the measurement result, and is released to the atmosphere by the blower 25a. On the other hand, the separation gas on the non-permeate side of the membrane separation module 20 passes through the flow meter 22c and the analyzer 17d, and the flow rate of the non-permeate side gas and the hydrogen concentration and monosilane concentration in the non-permeate side gas are measured. The non-permeate side gas is appropriately diluted with nitrogen based on the measurement result, and burned and removed by the combustion removal apparatus 23. The gas discharged by combustion by the combustion abatement device 23 is supplied to the bag filter 24 by the blower 25b and then released to the atmosphere by the blower 25c in order to remove foreign matters such as powder generated during the combustion. The

[Example 2]
Using the membrane separation module 20 having a membrane separation capacity of 4.8 L, the non-permeate side back pressure valve 21b is opened, the non-permeate side is set to normal pressure, the permeate side pressure is adjusted to -70 kPa, and the temperature of the supply gas is set to 80 ° C. The operation was performed in the same manner as in Example 1 except that. As a result, the SiH ₄ concentration of the separated permeate side gas was 0.052 vol%, and the hydrogen recovery rate was 63.3%, which was constant regardless of fluctuations in the exhaust gas flow rate.

[Example 3]
FIG. 5 shows that the exhaust gas treatment system satisfies the formula (2) (C ₁ = 0.5) using the conditions of Example 2 as initial conditions except that the pressure is adjusted to 50 kPaG by the non-permeate side back pressure valve 21b. ) It is the figure which showed the result of having monitored the change of the hydrogen recovery rate with respect to the years of use (converted value) at the time of operation. The service life (converted value) is a value obtained by converting the operation time in the acceleration test into the actual number of years. In the accelerated deterioration test, the total mixed gas flow rate was 50 times the actual test, and the supplied monosilane gas concentration and the supplied nitrogen gas concentration were constant. From this result, it is understood that long-term operation is possible while maintaining the hydrogen recovery rate by operating the exhaust gas treatment system while satisfying the formula (2).

[Example 4]
FIG. 6 shows the change in the hydrogen recovery rate with respect to the service life (converted value) when the exhaust gas treatment system is operated by satisfying the formula (3) (C ₂ = 1.0) with the conditions of Example 1 as initial conditions. It is the figure which showed the result of monitoring. From this result, it is understood that long-term operation is possible while maintaining the hydrogen recovery rate by operating the exhaust gas treatment system while satisfying the formula (3).

[Example 5]
FIG. 7 shows the exhaust gas treatment system in the same manner as in Example 1 except that a membrane separation module having a membrane separation capacity of 3.0 L was used as the initial condition, and nitrogen was added at 30 NL / min in the third component gas addition unit 10. a diagram showing the results obtained by monitoring changes in the hydrogen recovery rate for (4) satisfies (C 3 ₌ 1.0) age at the time of driving (converted value). From this result, it is understood that long-term operation is possible while maintaining the hydrogen recovery rate by operating the exhaust gas treatment system while satisfying the formula (4).

[Comparative Example 1]
FIG. 8 is a system diagram showing a configuration of an exhaust gas treatment system according to a comparative example. The exhaust gas treatment system according to the comparative example shown in FIG. 8 is not provided with a compressor, an airtight tank, a pressure accumulation valve, or a mass flow controller. The above-described CVD apparatus was connected to such an exhaust gas treatment system, and the operation was performed under the same conditions as in Example 1. The fluctuating exhaust gas was directly distributed to the membrane separation apparatus. As a result, the SiH ₄ concentration and the hydrogen recovery rate of the permeation side gas after separation varied as shown in Table 3 according to the variation of the exhaust gas flow rate. In addition, the SiH ₄ concentration of the permeate side gas was increased to 0.044 vol% at the maximum, and the dilution rate for atmospheric release had to be 2.3 times that of Example 1.

[Comparative Example 2]
The operation was performed under the same configuration and conditions as in Comparative Example 1 except that the membrane separation capacity of the exhaust gas treatment system was changed to 1.2L. As a result, as shown in Table 3, the concentration of SiH ₄ in the permeate side gas could be reduced, but the hydrogen recovery rate was lowered.

[Comparative Example 3]
FIG. 9 shows the change in the hydrogen recovery rate with respect to the service life (converted value) when the exhaust gas treatment system is operated without satisfying the formula (2) (C ₁ = 0.1) with the conditions of Example 1 as initial conditions. It is the figure which showed the result of having monitored. From this result, it is understood that when the exhaust gas treatment system is operated without satisfying the formula (2), the hydrogen recovery rate decreases in a short period of time.

[Comparative Example 4]
FIG. 10 shows the change in the hydrogen recovery rate with respect to the service life (converted value) when the exhaust gas treatment system is operated without satisfying the formula (3) (C ₂ = 0.25) with the conditions of Example 2 as initial conditions. It is the figure which showed the result of having monitored. From this result, it is understood that when the exhaust gas treatment system is operated without satisfying the expression (3), the hydrogen recovery rate is reduced in a short period of time.

[Comparative Example 5]
FIG. 11 shows the exhaust gas treatment system in the same manner as in Example 1 except that a membrane separation module with a membrane separation capacity of 3.0 L is used as the initial condition, and nitrogen is added at 30 NL / min in the third component gas addition unit 10. it is a diagram illustrating a (4) does not satisfy the (C 3 ₌ 0.2) as a result of monitoring the change in hydrogen recovery rate for age at the time of driving (converted value). From this result, it can be seen that when the exhaust gas treatment system is operated without satisfying the formula (4), the hydrogen recovery rate decreases in a short period of time.

  The present invention is not limited to the above-described embodiments and examples, and modifications such as various design changes can be made based on the knowledge of those skilled in the art, and such modifications have been added. Embodiments can also be included in the scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 Semiconductor manufacturing apparatus, 2 Pump part, 2a filter, 2b pump, 2c switching valve, 3 Gas storage part, 4 Flow control part, 5 Gas analysis part, 6 Membrane separation part, 6a Temperature control part, 6b Membrane separation apparatus, 6c Permeation side pressure control unit, 6d Non-permeation side pressure control unit, 6e Permeation side gas analysis unit, 6f Non-permeation side gas analysis unit, 7 Hydrogen gas treatment unit, 7a Hydrogen gas purification unit, 7b Dilution unit, 7c Blower, 8 Silane gas Treatment section, 8a Silane gas purification section, 8b Dilution section, 8c Detoxification section, 8d Blower, 10 Third component gas addition section, 11 Compressor, 12 PE-CVD apparatus, 13a Dry pump, 14 Filter, 15 Airtight tank, 16 Mass flow controller, 17a, 17b, 17c, 17d Analyzer, 18 Heat exchanger , 19 Circulation thermostat, 20 Membrane separation module, 21a Permeate side back pressure valve, 21b Non-permeate side back pressure valve, 22a, 22b, 22c Flow meter, 23 Combustion abatement device, 24 Bag filter, 25a, 25b, 25c Blower, 26 Compressor, 30 arithmetic control unit, 32 pressure accumulating valve, 33 switching valve, 100 exhaust gas treatment system.

Claims (3)

An exhaust gas treatment system for treating a mixed gas containing at least hydrogen and monosilane discharged from a semiconductor manufacturing apparatus,
A pump for exhausting the mixed gas discharged from the semiconductor manufacturing apparatus;
A compressor that compresses the mixed gas exhausted by the pump and sends it to the subsequent stage;
A gas storage unit for collecting and storing the compressed mixed gas;
A flow rate control unit for controlling the flow rate of the mixed gas supplied from the gas storage unit;
A membrane separator that selectively permeates hydrogen and separates monosilane and hydrogen from the mixed gas;
An exhaust gas treatment system comprising:   The exhaust gas treatment system according to claim 1, wherein when the operation is started, the operation is started after accumulating pressure in the gas storage unit.   The exhaust gas treatment system according to claim 1, further comprising a pressure control unit that controls a non-permeate side pressure of the membrane separation unit.

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