Exhaust Gas Treatment System

Abstract

To provide an exhaust gas treatment system that can divide exhaust gas into a plurality of detoxification devices, without requiring complicated control.SOLUTION: An exhaust gas treatment system 10, which detoxifies exhaust gas, has: an inlet pressure control part 30 connected to collecting piping L1 to which exhaust gas is supplied; and a plurality of detoxification treatment parts 40a, 40b and 40c connected to one another through a plurality of piping L3a, L3b and L3c branched from the inlet pressure control part 30. The inlet pressure control part 30 comprises a pressure sensor 32 and an automatic control valve 33 that controls the pressure sensor 32 so that an indicated value thereof becomes equal to a set value. The detoxification treatment parts 40a, 40b and 40c are provided with detoxification devices 42a, 42b and 42c and vacuum generators 43a, 43b and 43c provided at front stages of the detoxification devices.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an exhaust gas treatment system, and more particularly to an exhaust gas treatment system that treats exhaust gases discharged from a plurality of semiconductor and other electronic device manufacturing apparatuses. [Background technology]

[0002] In an exhaust gas treatment system, it is necessary to install an abatement device according to the flow rate of exhaust gas emitted by manufacturing equipment for semiconductors, etc. In particular, when the flow rate of exhaust gas is high, if one large abatement device is used to deal with it, the development and manufacturing costs of large abatement devices are generally high, so it is preferable to install standard abatement devices in parallel.

[0003] In particular, the exhaust gas flow rate of an exhaust gas treatment device connected to multiple semiconductor manufacturing devices varies depending on the number of devices in operation and their operating conditions. Therefore, in order to operate the device efficiently, an exhaust gas treatment device has been proposed that installs multiple decontamination devices and divides the exhaust gas (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-207771 [Patent Document 2] Patent No. 5958645 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when attempting to split the exhaust gas treatment equipment shown in Patent Document 1 to multiple abatement devices, complex control was required. More specifically, each abatement device is designed to be used under negative pressure conditions within the system to prevent external leakage of the gas being treated. When implementing splitting, it is conceivable to control the flow distribution by the pressure difference between the inlet pressures of each abatement device. However, the original gas pressure is very low, making it difficult to create a clear pressure difference, and high-precision pressure sensors are required. Furthermore, exhaust gas from semiconductor manufacturing equipment contains corrosive gases, powder, etc. depending on the type of film formation and process. Powder adhesion to pipes and sensors can cause discrepancies in the readings, making split control by pressure difficult.

[0006] In particular, in an exhaust gas treatment device such as that shown in Figure 1 of Patent Document 1, if an exhaust fan or other device is installed to maintain negative pressure in each abatement device, the negative pressure in abatement device 52a may be lower than that in abatement device 52b, resulting in suction from abatement device 52b and a backflow of hot air from the heating section. While installing a check valve is considered a possible solution, this is not acceptable in practical operation due to the risk of adhesion due to blockage by powder. For the same reason, installing a flow meter in the exhaust piping to control the flow rate is difficult because it is prone to malfunction due to powder and corrosive gases. Even if an exhaust fan is not installed, even if the equipment design takes into account piping pressure loss and other factors during the initial setup of the system, problems such as uneven flow rates of the exhaust gas diverted to each abatement device may occur due to blockage in the piping over time.

[0007] As in Patent Document 2, if there is a sufficient margin in the allowable treatment volume, treatment is possible even if backflow occurs, so it is possible to install them in parallel. However, as mentioned above, this requires the preparation of a large abatement device, which is not desirable from the viewpoint of equipment cost.

[0008] As described above, the diversion of exhaust gases, particularly from atmospheric pressure to slightly negative pressure, requires complex control, making it difficult to implement in practice.

[0009] Therefore, an object of the present invention is to provide an exhaust gas treatment system that can divide exhaust gas into a plurality of abatement devices without requiring complex control. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention provides an exhaust gas treatment system for detoxifying exhaust gas introduced through an exhaust gas inlet path, the exhaust gas treatment system including a plurality of detoxification treatment sections connected by a plurality of branch pipes branching from the exhaust gas inlet path, the detoxification treatment sections including a detoxification device and a vacuum generator provided upstream of the detoxification device, and an inlet pressure control section between the exhaust gas inlet path and the branch pipe, the inlet pressure control section including a pressure sensor and an automatic control valve that controls the pressure sensor so that the indicated value becomes a set value.

[0011] The inlet pressure control unit is also characterized in that it is provided with a pressure adjustment gas introduction path that introduces a pressure adjustment gas upstream of the pressure sensor so that the indicated value of the pressure sensor becomes the set value, and the pressure adjustment gas is either nitrogen, dry air, or oxygen.

[0012] Furthermore, the inlet pressure control unit is characterized by having a pressure relief path and a three-way valve that switches the exhaust gas flow path to the pressure relief path when the pressure sensor's indication value is greater than a set value.

[0013] The vacuum generator is preferably a positive displacement multi-stage Roots type vacuum pump or an ejector. [Effects of the Invention]

[0014] According to the present invention, since a vacuum generator is provided in front of the decontamination equipment of the decontamination treatment section, backflow does not occur even when the vacuum generator of another decontamination treatment section sucks in exhaust gas. Also, since the inlet pressure control section controls the pressure sensor's reading to the set value by an automatic control valve, it is possible to prevent any influence on the systems of semiconductor manufacturing equipment that generate exhaust gas.

[0015] Furthermore, by providing a pressure adjusting gas introduction path and a pressure relief path, it is possible to appropriately respond to cases where the flow rate of exhaust gas is insufficient or temporarily excessive. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is an explanatory diagram showing an example of an exhaust gas treatment system according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are denoted by similar reference numerals, and detailed descriptions will be omitted as appropriate. Figure 1 is an explanatory diagram showing one embodiment of an exhaust gas treatment system of the present invention.

[0018] The exhaust gas treatment system 10 in this embodiment is a system that detoxifies exhaust gas discharged from a plurality of semiconductor manufacturing apparatuses 20a, 20b, 20c, 20d, 20e, etc. (hereinafter, sometimes collectively referred to as "semiconductor manufacturing apparatuses 20").

[0019] The exhaust gases discharged from the multiple semiconductor manufacturing devices 20a, 20b, 20c, 20d, 20e, etc. are respectively sucked into dry pumps 21a, 21b, 21c, 21d, 21e, etc. (hereinafter, collectively referred to as "dry pumps 21") and merge into a collecting pipe L1 (the exhaust gas introduction path of the present invention).

[0020] The exhaust gas treatment system 10 is roughly composed of an inlet pressure control unit 30 connected to a collecting pipe L1, a plurality of abatement treatment units 40a, 40b, 40c, etc., and branch pipes L3a, L3b, L3c connecting the inlet pressure control unit 30 and the plurality of abatement treatment units 40a, 40b, 40c, etc.

[0021] The inlet pressure control unit 30 is connected to a path L2 via a collecting pipe L1 and a three-way valve 31. A pressure relief path L4 is connected to one side of the three-way valve 31. A processing facility such as a collecting scrubber (not shown) is provided on the pressure relief path L4. A pressure sensor 32 that detects pressure and an automatic control valve 33 that controls the aperture so that the pressure indicated by the pressure sensor 32 becomes a predetermined set value are provided on the path L2.

[0022] In addition, in case the exhaust gas flow rate is low and the pressure indication value of the pressure sensor 32 does not reach the set value even when the opening of the automatic control valve 33 is narrowed to the lower limit, a pressure adjustment gas supply path L5 is provided to introduce nitrogen gas as a pressure adjustment gas into the path L2.

[0023] The pressure adjustment gas supply path L5 is provided with a mass flow controller 34 that adjusts the flow rate of the pressure adjustment gas so that the pressure indicated by the pressure sensor 32 matches the set value, and a valve 35. In order to prevent clogging of the pressure adjustment gas supply path L5, a constant purge line L6 equipped with a needle valve 36 is branched off from the upstream side of the mass flow controller 34.

[0024] The exhaust gas sent out from the automatic control valve 33 of the inlet pressure control section 30 is introduced into a plurality of abatement treatment sections 40a, 40b, 40c... via branch pipes L3a, L3b, L3c....

[0025] The detoxification processing unit 40a is provided with a water-cooled thermal decomposition type detoxification device 42a on a path L7a connected to the branch pipe L3a via a gate valve 41a. Furthermore, a dry pump 43a is provided between the gate valve 41a and the detoxification device 42a. The detoxification processing units 40b, 40c, etc. are similarly configured. In this embodiment, the dry pump 43a is a positive displacement, multi-stage Roots type vacuum pump that corresponds to the detoxification capacity of the detoxification device 42a.

[0026] Next, the exhaust gas treatment process using the exhaust gas treatment system of the present invention will be described. Here, it is assumed that each of the abatement devices 42a, 42b, and 42c has the capacity to abatement the exhaust gas equivalent to five semiconductor manufacturing devices 20. Therefore, when five semiconductor manufacturing devices 20a, 20b, 20c, 20d, and 20e are in operation, the abatement device 42a and dry pump 43a are operated to abatement the exhaust gas.

[0027] When the dry pump 43a starts operating and exhaust gas is sucked from the collecting pipe L1 into the detoxification device 42a, the indication value of the pressure sensor 32 increases toward the vacuum side, so the opening of the automatic control valve 33 is controlled to be reduced to the set value of -1 kPaG to -3 kPaG.

[0028] If the automatic control valve 33 were not provided, the suction of the dry pump 43a would also create a high vacuum in the collecting pipe L1, which would reduce the workload of the dry pump 21 at the lower stage of the semiconductor manufacturing equipment 20, causing the dry pump 21 to generate less heat and potentially causing the dry pump 21 to become clogged with powder in the exhaust gas.

[0029] The setting value of the pressure sensor 32 is set to -1 kPaG to -3 kPaG because in a normal decontamination system that does not incorporate the decontamination treatment system of the present invention, the area between the dry pumps 21a, 21b, 21c, 21d, and 21e and the collecting pipe L1 is in a slightly negative pressure state to prevent gas from leaking to the outside, and the same level is set in this system.

[0030] Furthermore, when the total amount of exhaust gas from semiconductor manufacturing equipment 20 is small, pressure adjustment gas is introduced from pressure adjustment gas supply path L5 as described above, and the reading of pressure sensor 32 is controlled to be the set value.

[0031] On the other hand, if the total amount of exhaust gas from the semiconductor manufacturing equipment 20 temporarily becomes a large flow rate, or if the processing capacity of the detoxification treatment unit 40a decreases and the reading of the pressure sensor 32 exceeds the set value, the exhaust gas from the semiconductor manufacturing equipment 20 is sent to the pressure relief path L4 via the three-way valve 31.

[0032] Here, when the sixth semiconductor manufacturing equipment 20f starts operation, the abatement capacity of the abatement equipment 42a will be exceeded, so the abatement equipment 42b and dry pump 43b of the abatement processing unit 40b are remotely started. Then, the exhaust gas from the semiconductor manufacturing equipment 20 is distributed and sent to the abatement processing units 40a and 40b via branch pipes L3a and L3b. Similarly, when the eleventh semiconductor manufacturing equipment 20 starts operation, the abatement equipment 42c and dry pump 43c of the abatement processing unit 40b are remotely started, and the exhaust gas is distributed and sent to the abatement processing units 40a, 40b, and 40c via branch pipes L3a, L3b, and L3c.

[0033] Because a dry pump 43a is provided upstream of the detoxification device 42a, the exhaust gas in the path L7a does not flow back even when the dry pump 43b is operated. Similarly, the exhaust gas in the pipe L7b does not flow back. Therefore, even without a complex control mechanism, it is possible to easily control the distribution of the exhaust gas to multiple detoxification devices.

[0034] In this way, multiple abatement devices can be installed side by side and flow division control is possible, which allows for more efficient operation of the abatement devices and significantly reduces equipment costs compared to when one large abatement device is always in use. With one large abatement device, at least one backup device is required for stable abatement treatment, meaning two large abatement devices are required for the facility. On the other hand, if the same treatment capacity is required using abatement devices that are about 20% of the size of the large device, the treatment system of the present invention requires five normally operating abatement devices and one backup device. Therefore, the excess capacity when backup is not required is 20% of the 100%, making it possible to build an economical facility.

[0035] Furthermore, if semiconductor manufacturing equipment is added to an existing facility and a corresponding abatement system must also be added, the exhaust gas treatment system of the present invention allows for efficient design of exhaust piping within the facility by simply connecting the exhaust gas piping from the downstream side of the semiconductor manufacturing equipment to be added to the collective piping L1 and adding and connecting the corresponding abatement treatment unit to a branch piping. For example, by consolidating the installation locations of the abatement treatment units, it is possible to share a backup abatement unit. Furthermore, depending on the layout of the branch piping, it is easy to install the abatement treatment unit outside the clean room of the semiconductor manufacturing equipment, allowing for effective use of space within the clean room and providing a high degree of design freedom.

[0036] In the above embodiment, positive displacement multi-stage Roots vacuum pumps are used as the dry pumps 43a, 43b, and 43c. Positive displacement pumps have a limit to the amount of fluid transferred to the downstream stage, but they enable the flow to be diverted to multiple abatement treatment units without the need for individual feedback control. Furthermore, multi-stage Roots pumps are preferable because they are designed with narrow clearances between each stage, which increases flow resistance and makes it less likely for sudden backflow to occur even if the power of the dry pump 43a is stopped.

[0037] As mentioned above, a positive displacement multi-stage Roots type vacuum pump is preferred, but any device that can suck exhaust gas into the abatement device and prevent backflow by creating pressure on the primary and secondary sides can be used, so various vacuum generators such as ejectors and exhaust blowers can be used in addition to vacuum pumps. For example, if an ejector is used, there is the disadvantage that the amount of exhaust gas on the secondary side increases, but there is also the advantage that negative pressure can be controlled by controlling the flow rate of the driving fluid.

[0038] In the above embodiment, nitrogen is used as the pressure adjusting gas, but the type of gas is not limited thereto. Various gases can be used depending on the components of the exhaust gas and the type of detoxification device. For example, if the exhaust gas does not contain combustible gases such as SiH4 and H2, dry air may be used as the pressure adjusting gas. Furthermore, if the reactivity of the detoxification treatment is increased, oxygen may also be introduced as the pressure adjusting gas.

[0039] The set value of the pressure sensor 32 is preferably atmospheric pressure to slightly negative pressure, but is not limited to the above embodiment. Furthermore, the automatic control valve 33 can also be controlled by the rotation speed of the dry pumps 43a, 43b, and 43c.

[0040] The detoxification treatment units 40a, 40b, and 40c can be maintained by closing the gate valves 41a, 41b, and 41c.

[0041] The detoxification devices 42a, 42b, 42c are not limited to the water-cooled thermal decomposition type, but may be any known type capable of detoxifying harmful components of exhaust gas, such as a heater type or a plasma type.

[0042] The multiple semiconductor manufacturing equipment 20 do not necessarily have to be the same equipment, and may be equipment for manufacturing various electronic devices other than semiconductor manufacturing process chambers, which use various gases depending on the type of film formation and process and discharge exhaust gases corresponding to those gases. If there is a possibility of powder or contamination in the piping depending on the type of exhaust gas, a filter or scrubber may be provided downstream of the dry pump 21. The exhaust gas treatment system of the present invention can be applied to exhaust gas treatment when there is a single semiconductor manufacturing equipment rather than multiple ones, and can also be applied to exhaust gas treatment in chemical plants.

[0043] The above describes the exhaust gas treatment system of the present invention based on example embodiments, but the present invention is not limited to the configurations described in the above example embodiments, and as mentioned above, the configuration can be changed as appropriate within the scope of the spirit of the invention. [Explanation of symbols]

[0044] 10...exhaust gas treatment system, 20 (20a, 20b, 20c, 20d, 20e, 20f)...semiconductor manufacturing equipment, 21 (21a, 21b, 21c, 21d, 21e, 21f)...dry pump, 30...inlet pressure control unit, 31...three-way valve, 32...pressure sensor, 33...automatic control valve, 34...mass flow controller, 35...valve, 36...needle valve, 40 (40a, 40b, 40c)...abatement treatment unit, 41a, 41b, 41c...gate valve, 42a, 42b, 42c...abatement device, 43a, 43b, 43c...dry pump, L1... Collecting pipe, L2... Route, L3a, L3b, L3c... Branch pipe, L4... Pressure relief route, L5... Pressure adjustment gas supply route, L6... Continuous purge line, L7a, L7b... Route

Claims

1. In an exhaust gas treatment system that detoxifies exhaust gas introduced through an exhaust gas introduction path, a plurality of detoxification treatment units connected by a plurality of branch pipes branched from the exhaust gas introduction path, The abatement treatment unit includes: a detoxification device and a vacuum generator provided in front of the detoxification device, an inlet pressure control unit is provided between the exhaust gas introduction path and the branch pipe; The inlet pressure control unit A pressure sensor; an automatic control valve that controls the pressure sensor so that the indicated value becomes a set value; An exhaust gas treatment system characterized by:

2. 2. The exhaust gas treatment system according to claim 1, wherein the inlet pressure control unit is provided with a pressure adjustment gas introduction path that introduces a pressure adjustment gas upstream of the pressure sensor so that the indicated value of the pressure sensor becomes a set value.

3. 3. The exhaust gas treatment system according to claim 2, wherein the pressure adjusting gas is any one of nitrogen, dry air, and oxygen.

4. 3. The exhaust gas treatment system according to claim 2, wherein the inlet pressure control unit has a three-way valve that is provided with a pressure relief path and switches the exhaust gas flow path to the pressure relief path when the pressure sensor reading is greater than a set value.

5. 5. The exhaust gas treatment system according to claim 1, wherein the vacuum generator is a positive displacement multi-stage Roots type vacuum pump.

6. 5. The exhaust gas treatment system according to claim 1, wherein the vacuum generator is an ejector.

7. An exhaust gas treatment process for detoxifying exhaust gases emitted from a plurality of semiconductor manufacturing devices using the exhaust gas treatment system according to claim 1, If the number of operating semiconductor manufacturing equipment does not exceed the abatement capacity of one abatement treatment unit, abatement treatment is performed in one abatement treatment unit, When the number of operating semiconductor manufacturing devices exceeds the abatement capacity of one abatement treatment unit, another abatement treatment unit is started, and the exhaust gas is distributed by the branch pipe and sent to the plurality of abatement treatment units for abatement treatment. An exhaust gas treatment process characterized by:

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