Vacuum exhaust system

Abstract

Provided is a vacuum exhaust system (10) that can send exhaust gas and diluent gas to a predetermined location while maintaining a constant temperature without lowering a temperature of the exhaust gas and the diluent gas as much as possible. The vacuum exhaust system (10) includes: a gas exhaust pipe (14) that is connected to a subsequent stage of a vacuum pump (12) and has a vacuum heat insulating pipe structure with a vacuum layer (21) between an inner pipe (19), through which used gas (G1) discharged from the vacuum pump (12) passes, and an outer pipe (20) surrounding the inner pipe (19); and a diluent gas introduction pipe (24) that introduces diluent gas (G2) for heating the used gas (G1) into the inner pipe (19) so that the used gas (G1) is maintained in a gaseous state in the gas exhaust pipe (14).

Description

VACUUM EXHAUST SYSTEM

[0001] The present invention relates to a vacuum exhaust system using a vacuum pump.

[0002] For example, in a semiconductor manufacturing treatment process, chemical vapor deposition (CVD) , in which a semiconductor, an insulator, a metal film, or the like is deposited on a semiconductor wafer to form a film using a chemical vapor phase reaction, and dry etching treatment are performed, and various gases such as silane (SiH-i) gas are used in a process chamber. Then, a used gas discharged from the process chamber is sucked by a dry pump or the like, further introduced into a detoxification apparatus via a gas exhaust pipe, and subjected to detoxification treatment in the detoxification apparatus (see, for example, PTL 1 ) .

[0003] In such a semiconductor manufacturing treatment process, when the used gas is subjected to cooling or the like, the used gas solidifies into a film or powder and adheres to an exhaust pipe other than the process chamber, and the interiors of the dry pump and the detoxification apparatus, and results in deposits that cause pipe blockage. Therefore, frequent maintenance is required. Further, when using a liquid process gas, since the used gas is re-liquefied in the exhaust pipe other than the process chamber, and the interiors of the dry pump and the detoxification apparatus, maintenance cannot be easily performed, and separate measures are required.

[0004] For the maintenance, in a conventional semiconductor manufacturing treatment process, at each location where the semiconductor wafer is formed, each time process treatment is completed, in accordance with the type of adhering product, a cleaning gas such as chlorine trifluoride (CIF3) , nitrogen fluoride (NF3) , or hydrogen chloride (HC1) is periodically introduced into the process chamber to decompose and discharge adhering material, thereby cleaning a reaction chamber and an exhaust pipe of a semiconductor processing apparatus, the dry pump, and the detoxification apparatus (see, for example, PTL 1) .

[0005] In general, as the used gas and the cleaning gas are heated to a higher temperature of 100°C or higher, the decomposing and dischargingof the adhering material can be more efficiently performed.

[0006] Therefore, the used gas and the cleaning gas (hereinafter collectively referred to as "used exhaust gas") flowing from the process chamber through the dry pump toward the detoxification apparatus several meters away from the dry pump are preferably maintained at a high temperature of 100°C or higher and introduced into the detoxification apparatus .

[0007] Therefore, a method has also been proposed in which between the dry pump and the detoxification apparatus, by adding diluent gas heated to about 300 °C to the used exhaust gas discharged from the dry pump so as to be mixed with the used gas, the used gas is heated to 150 to 200°C and introduced into the detoxification apparatus (see, for example, PTL 2) .

[0008] Note that in PTL 2, a heating wire is used as a heat source for heating the diluent gas to a predetermined temperature.

[0009] Further, a method has also been proposed in which heat generated by the dry pump is used as the heat source for heating the diluent gas, introduced into the detoxification apparatus, to the predetermined temperature (see, for example, PTL 3) .

[0010] [PTL 1] Japanese Patent No. 3456933[PTL 2] Japanese Patent Application Publication No. H04-330388[PTL 3] Japanese Patent No. 6418838[Summary of the Invention]

[0011] In the conventional methods described in PTL 2 and PTL 3 described above, the diluent gas and the exhaust gas heated to a predetermined temperature are introduced into the detoxification apparatus or the like through a general gas pipe. Therefore, there has been a problem in that temperatures of the diluent gas and the exhaust gas are affected by a system usage environment and decreased while the diluent gas and the exhaust gas pass through the pipe, and it is difficult to maintain the predetermined temperature.

[0012] The present invention has been made in view of such a conventional problem, as there is a technical problem that need to be solved in order to provide a vacuum exhaust system that can send theexhaust gas and the diluent gas to a predetermined location while maintaining a constant temperature without lowering the temperatures of the exhaust gas and the diluent gas as much as possible, and an object of the present invention is to solve this problem.

[0013] The present invention has been proposed to achieve the above object, and the invention according to claim 1 provides a vacuum exhaust system including: a vacuum pump configured to suck and discharge an exhaust gas discharged from a process chamber; a gas pipe connected to a subsequent stage of the vacuum pump and having a vacuum heat insulating pipe structure with a vacuum between an inner pipe, through which the exhaust gas discharged from the vacuum pump passes, and an outer pipe surrounding the inner pipe; and a diluent gas introduction portion configured to introduce diluent gas for heating the exhaust gas into the inner pipe so as to maintain the exhaust gas in a gaseous state in the inner pipe.

[0014] According to this configuration, the exhaust gas and the diluent gas are supplied to a predetermined location by passing the diluent gas heated to maintain the exhaust gas in the gaseous state into the inner pipe of the gas pipe, through which the exhaust gas passes, the gas pipe having a vacuum heat insulating structure with the vacuum between the inner pipe and the outer pipe surrounding the inner pipe. Therefore, in the gas pipe having the vacuum heat insulating structure with a vacuum layer between the inner pipe and the outer pipe, since heat transfer between the inner pipe and the outer pipe is blocked by the vacuum layer, the exhaust gas and the diluent gas passing through the inner pipe are sent through the inner pipe to the predetermined location without losing heat to the outer pipe side while maintaining the same temperature, that is, the temperature at which the exhaust gas is maintained in the gaseous state. Thus, in the vacuum exhaust system using the gas pipe having the vacuum heat insulating structure, thermal control of the exhaust gas and the diluent gas is facilitated, and thermal efficiency of the exhaust gas and the diluent gas can be improved.

[0015] The invention according to claim 2 provides the vacuum exhaust system in the configuration according to claim 1, in which the gas pipehas a sealed structure with a vacuum between the inner pipe and the outer pipe .

[0016] According to this configuration, the vacuum exhaust system has the sealed structure with the vacuum between the inner pipe and the outer pipe. Therefore, once a sealed evacuated structure is formed between the inner pipe and the outer pipe, a vacuum state can be easily maintained thereafter. This facilitates management of the vacuum state.

[0017] The invention according to claim 3 provides the vacuum exhaust system in the configuration according to claim 1, in which the diluent gas is heated by the vacuum pump.

[0018] According to this configuration, the diluent gas can be heated to a predetermined temperature by effectively utilizing compression heat in the pump, exhaust heat from a housing due to the compression heat, heat generated from a motor, or the like.

[0019] The invention according to claim 4 provides the vacuum exhaust system in the configuration according to claim 1, in which the gas pipe is provided to be connected between an exhaust port of the vacuum pump and equipment for detoxification treatment of the exhaust gas discharged from the vacuum pump.

[0020] According to this configuration, the exhaust gas can be sent into the equipment while the temperature of the exhaust gas discharged from the exhaust port of the vacuum pump and flowing toward the equipment for detoxification treatment is maintained at a state favorable for the detoxification treatment of the exhaust gas in the equipment for detoxification treatment. This can be expected to improve an efficiency of the detoxification treatment of the exhaust gas in the equipment for detoxification treatment.

[0021] The invention according to claim 5 provides the vacuum exhaust system in the configuration according to claim 1, in which the vacuum pump includes an exhaust port connected to the gas pipe and having a vacuum heat insulating pipe structure with a vacuum between an inner pipe, through which the exhaust gas discharged from the vacuum pump passes, and an outer pipe surrounding the inner pipe.

[0022] According to this configuration, the exhaust port itself of thevacuum pump also has the vacuum heat insulating structure with the vacuum between the inner pipe and the outer pipe surrounding the inner pipe.Therefore, also in the exhaust port having the vacuum heat insulating structure with the vacuum between the inner pipe and the outer pipe, since the heat transfer between the inner pipe and the outer pipe is blocked by the vacuum layer, the exhaust gas and the diluent gas passing through the inner pipe of the exhaust port are sent through the inner pipe to the predetermined location without losing heat to the outer pipe side while maintaining the same temperature, that is, the temperature at which the exhaust gas is maintained in the gaseous state. Thus, in the vacuum exhaust system using the gas pipe having the vacuum heat insulating structure, the thermal control of the exhaust gas and the diluent gas is further facilitated, and the thermal efficiency of the exhaust gas and the diluent gas can be further improved.

[0023] According to the present invention, by using the gas pipe having the vacuum heat insulating structure with the vacuum between the inner pipe and the outer pipe, the exhaust gas and the diluent gas passing through the inner pipe can be sent through the inner pipe to the predetermined location without losing heat to the outer pipe side while maintaining the same temperature, that is, the temperature at which the exhaust gas is maintained in the gaseous state. Thus, in the vacuum exhaust system, the thermal control of the exhaust gas and the diluent gas is easily managed, and the thermal efficiency of the exhaust gas and the diluent gas can be improved.

[0024] [Fig. 1]Fig. 1 is a schematic diagram showing a main part configuration of a semiconductor manufacturing process apparatus using a vacuum exhaust system according to an embodiment of the present invention.[Fig. 2]Fig. 2 shows an example of a gas exhaust pipe used in the semiconductor manufacturing process apparatus, Fig. 2 (a) is a schematic cross-sectional view of the gas exhaust pipe taken along its longitudinal direction, and Fig. 2 (b) is an A-A cross-sectional view in Fig. 2 (a) .[Fig. 3]Fig. 3 is a diagram showing an example of a sublimation temperature curve .[ Fig . 4 ] Fig. 4 is a diagram showing an example of evaluation results. [Fig. 5] Fig. 5 is a schematic diagram showing a modification of the vacuum exhaust system according to the present invention.

[0025] In order to achieve a purpose of providing a vacuum exhaust system that can send exhaust gas and diluent gas to a predetermined location while maintaining a constant temperature without lowering temperatures of the exhaust gas and the diluent gas as much as possible, the present invention has been completed by adopting a configuration including: a vacuum pump configured to suck and discharge an exhaust gas discharged from a process chamber; a gas pipe connected to a subsequent stage of the vacuum pump and having a vacuum heat insulating pipe structure with a vacuum between an inner pipe through which the exhaust gas discharged from the vacuum pump passes and an outer pipe surrounding the inner pipe; and a diluent gas introduction portion configured to introduce a diluent gas for heating the exhaust gas into the inner pipe to maintain the exhaust gas in a gaseous state in the pipe.Examples

[0026] Hereinafter, an example according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that in the following example, when referring to the number, numerical value, amount, range, and the like of components, unless it is specifically specified or it is clearly limited to a specific number in principle, it is not limited to the specific number, and may be greater than or less than the specific number.

[0027] Further, when referring to the shape or positional relationship of the components and the like, for example, unless it is specifically specified or it is clearly considered otherwise in principle, it includes things and the like that are substantially approximate to or similar to the shape.

[0028] Further, in the drawings, characteristic parts may be exaggerated, for example, by being enlarged, in order to make the features easier to understand, and dimensional ratios of the components are not necessarily the same as in reality. Furthermore, in the cross- sectional views, hatching of some components may be omitted in order to make a cross-sectional structure of the components easier to understand.

[0029] Further, in the following description, expressions indicating directions such as up and down and left and right are not absolute, and are appropriate when it is a posture in which each part of the semiconductor manufacturing process of the present invention is depicted, but when the posture changes, it should be interpreted to be changed according to a change in posture. Furthermore, the same elements are denoted by the same reference numerals throughout the description of the example .

[0030] Fig. 1 is a schematic diagram showing a main part configuration of a semiconductor manufacturing process apparatus 10 using a vacuum exhaust system according to the embodiment of the present invention. An overall configuration of the semiconductor manufacturing process apparatus 10 will be schematically described with reference to Fig. 1.

[0031] A semiconductor manufacturing process apparatus 10 shown in Fig. 1 includes a process chamber 11 in which semiconductor wafers are processed and treated, a vacuum pump 12, an exhaust gas detoxification apparatus 13, and the like. For example, a process gas for process treatment of a semiconductor wafer, a cleaning gas for cleaning treatment, or the like is supplied into the process chamber 11. Note that the process gas is, for example, silane (SiEh) gas, and the cleaning gas is, for example, ClFg (chlorine trifluoride) , NF3 (nitrogen trifluoride) , or HCI (hydrogen chloride) . After the treatment in the process chamber 11 is completed, the process gas or the cleaning gas in the process chamber 11 is sent from the process chamber 11 to the vacuum pump 12 through a gas exhaust pipe 14. Hereinafter, the process gas and the cleaning gas will be collectively referred to as "used exhaust gas Gl". The used exhaust gas Gl sent to the vacuum pump 12 is gradually pressurized to near atmospheric pressure inside the vacuum pump 12 and heated to asublimation temperature, then discharged into a gas exhaust pipe 15, and sent to the exhaust gas detoxification apparatus 13 through an inside of the gas exhaust pipe 15. Then, after the used exhaust gas G1 is detoxified in the exhaust gas detoxification apparatus 13, it is discharged into the atmosphere.

[0032] Further, in order to prevent temperature of the used exhaust gas G1 from cooling below the sublimation temperature until the used exhaust gas G1 discharged from the vacuum pump 12 into the gas exhaust pipe 15 is detoxified inside the exhaust gas detoxification apparatus 13, diluent gas G2 heated to a high temperature equal to or higher than the sublimation temperature is introduced into the gas exhaust pipe 15 from an arbitrary position of the gas exhaust pipe 15, and the used exhaust gas G1 and the diluent gas G2 are mixed and sent to the exhaust gas detoxification apparatus 13 while maintaining the high temperature (equal to or higher than the sublimation temperature) . Note that the diluent gas G2 in this example is, for example, a gas such as N2 (nitrogen) , NH4CI (ammonium chloride) , or AICI3 (aluminum chloride) .

[0033] Then, in the semiconductor manufacturing process apparatus 10 shown in Fig. 1, the gas exhaust pipe 15, which is one of embodiments of the present invention, is used as a gas pipe in which temperature of mixed gas G3 of the used exhaust gas G1 and the diluent gas G2 flowing from the vacuum pump 12 toward the exhaust gas detoxification apparatus 13 does not easily drop.

[0034] Fig. 2 is a diagram showing an example of the gas exhaust pipe 15 used in the semiconductor manufacturing process apparatus, Fig. 2 (a) is a schematic cross-sectional view of the gas exhaust pipe 15 taken along its longitudinal direction, and Fig. 2 (b) is a A-A cross-sectional view in Fig . 2 (a) .

[0035] The gas exhaust pipe 15 shown in Fig. 2 is formed as one pipe by sequentially connecting a plurality of pipes in a pipe axial direction. Flanges 16 are provided at connection points, and an O-ring 17 is interposed between the flanges 16 and outsides of the flanges 16 are tightened with a clamp material 18 to form a continuous pipe structure.

[0036] More specifically, the gas exhaust pipe 15 is connected to asubsequent stage or a gas exhaust port (an exhaust port) of the vacuum pump 12, and has a double pipe structure including an inner pipe 19 through which the used exhaust gas G1 discharged from the vacuum pump 12 passes and an outer pipe 20 provided around the inner pipe 19 so as to cover an entire outer circumferential surface of the inner pipe 19, and is further configured to have a vacuum heat insulating pipe structure with a vacuum layer provided between the inner pipe 19 and the outer pipe 20. Then, the gas exhaust pipe 15 has one end of the inner pipe 19 coupled and connected to a gas exhaust port (not shown) of the vacuum pump 12, and the other end of the inner pipe 19 coupled and connected to an exhaust gas introduction port (not shown) of the exhaust gas detoxification apparatus 13. Note that the outer pipe 20 forming a vacuum layer 21 with the inner pipe 19 has both ends closely connected to the outer circumferential surface of the inner pipe 19, and a gap between the inner pipe 19 and the outer pipe 20, that is, a portion where the vacuum layer 21 is formed is a space formed as a sealed structure.

[0037] Further, the gas exhaust pipe 15 is provided with a vacuum suction port 22 that communicates with the gap between the inner pipe 19 and the outer pipe 20, that is, a space forming the vacuum layer 21. The vacuum suction port 22 is closed with a sealing plug 23 after the air inside the space formed between the inner pipe 19 and the outer pipe 20 is evacuated to form the vacuum layer 21. Note that the space forming the vacuum layer 21 may not be a continuous space from one end of the gas exhaust pipe 15 to the other end, and may be divided into a plurality of rooms. When divided, the vacuum suction port 22 and the sealing plug 23 are provided for each divided portion. Note that like the gas exhaust pipe 15, an exhaust port (not shown) of the vacuum pump 12, to which the gas exhaust pipe 15 is connected, preferably has the vacuum heat insulating pipe structure with the vacuum between the inner pipe through which the used exhaust gas G1 passes and the outer pipe surrounding the inner pipe.

[0038] Further, the gas exhaust pipe 15 is provided with a diluent gas introduction pipe 24 as a diluent gas introduction part that communicates from an outside of the outer pipe 20 to an inside of the inner pipe 19.One end of the gas exhaust pipe 15 communicates with a diluent gas source, and the diluent gas G2 is introduced into the inner pipe 19 through the diluent gas introduction pipe 24.

[0039] Note that a temperature of the diluent gas G2 introduced from the diluent gas source into the inner pipe 19 through the diluent gas introduction pipe 24 varies depending on the used exhaust gas Gl, and the diluent gas G2 is heated to a temperature sufficient to maintain the used exhaust gas Gl in the gaseous state, that is, a temperature higher than the sublimation temperature of the used exhaust gas Gl, and is introduced into the inner pipe 19, so that the used exhaust gas Gl can be instantly raised to the temperature equal to or higher than the sublimation temperature. The temperature is determined, for example, with reference to a table drawn with a sublimation temperature curve shown in Fig. 3. In Fig. 3, when the diluent gas G2 is NH4CI (ammonium chloride) , it is heated to about 340°C, and when AICI3 (aluminum chloride) is used, it is heated to about 200°C and introduced into the inner pipe 19.

[0040] Next, an operation of the semiconductor manufacturing process apparatus 10 will be described. The used exhaust gas Gl, which has passed from the process chamber 11 through the vacuum pump 12, has been heated to a high temperature by compression in the vacuum pump 12, and has been discharged into the inner pipe 19 of the gas exhaust pipe 15 in a high- temperature gas state, is sent toward the exhaust gas detoxification apparatus 13. The used exhaust gas Gl is mixed with the diluent gas G2, which is fed from the diluent gas introduction pipe 24 through the inner pipe 19 provided at an arbitrary position of the gas exhaust pipe 15 and has a temperature higher than that of the used exhaust gas Gl . Then, the mixed gas G3 heated to a temperature (equal to or higher than the sublimation temperature) higher than the used exhaust gas Gl is generated, and the mixed gas G3 containing the used exhaust gas Gl is introduced into the exhaust gas detoxification apparatus 13 while being maintained in the gaseous state. Further, the mixed gas G3 containing the used exhaust gas Gl introduced into the exhaust gas detoxification apparatus 13 is detoxified in the exhaust gas detoxification apparatus 13 and then discharged into the atmosphere.

[0041] Therefore, in the semiconductor manufacturing process apparatus 10 of this example, the gas pipe having a vacuum heat insulating structure with the vacuum layer 21 between the inner pipe 19 and the outer pipe 20 surrounding the inner pipe 19, that is, the gas exhaust pipe 15 is used, the diluent gas G2 heated so that the used exhaust gas G1 is maintained in the gaseous state is passed through the inner pipe 19 of the gas exhaust pipe 15 through which the used exhaust gas G1 passes, and the used exhaust gas G1 and the diluent gas G2 are mixed to generate the mixed gas G3, to be sent to the exhaust gas detoxification apparatus 13 which is the predetermined location. Here, in the gas exhaust pipe 15 having the vacuum heat insulating structure with the vacuum layer 21 between the inner pipe 19 and the outer pipe 20, since heat transfer between the inner pipe 19 and the outer pipe 20 is blocked by the vacuum layer 21, the mixed gas G3, which is a mixture of the used exhaust gas G1 and the diluent gas G2 passing through the inner pipe 19, is sent through the inner pipe 19 to the predetermined location, that is, the exhaust gas detoxification apparatus 13 without losing heat to the outer pipe 20 side, while maintaining the same temperature, that is, the temperature at which the used exhaust gas G1 is maintained in the gaseous state. Thus, in the semiconductor manufacturing process apparatus 10 using the gas exhaust pipe 15 having the vacuum heat insulating structure, thermal control (prevention of temperature drop) is facilitated, and thermal efficiency can be improved.

[0042] Fig. 4 is a diagram showing a verification result comparing a case where the gas exhaust pipe 15 in this example is used and a case where a conventional pipe structure is used. In this verification, a straight pipe with a length of 2.5 meters was used, gas at 250°C was allowed to flow from an inlet side, and a temperature at an outlet side was measured. (A) in Fig. 4 shows an amount of temperature drop when a single pipe was used, and the amount of temperature drop was about 120 °C, which was 50% loss. (B) in the same figure shows the amount of temperature drop when a heat insulating material was attached to an outer periphery of the single pipe and used, and the amount of temperature drop was about 75°C, which was about 25% loss. (C) in the same figure showsthe temperature drop when using the gas exhaust pipe 15 of this example in which the vacuum layer 21 is provided between the inner pipe 19 and the outer pipe 20, and the amount of temperature drop was about 25°C, which was 10% loss. From this verification result, it was found that when the gas exhaust pipe 15 of this example was used, the temperature drop could be reduced to about 10 to 20% compared to when a conventional pipe was used, and the thermal efficiency was improved.

[0043] In the semiconductor manufacturing process apparatus 10 of the above example, a structure has been disclosed in which the diluent gas introduction pipe 24 is connected immediately after the gas exhaust pipe 15 led outside the vacuum pump 12, and the diluent gas G2 is introduced into the inner pipe 19 of the gas exhaust pipe 15 through the diluent gas introduction pipe 24, however, instead of this structure, for example, as shown in FIG. 5, it is also possible to adopt a structure in which the diluent gas introduction pipe 24 is connected to the interior of the vacuum pump 12, and the diluent gas G2 sent from the diluent gas source through the diluent gas introduction pipe 24 is mixed with the used exhaust gas G1 in the vacuum pump 12.

[0044] As a structure in which the used exhaust gas G1 and the diluent gas G2 are mixed in the vacuum pump 12 in this manner, the diluent gas introduction pipe 24 may be further provided to surround an outer periphery of the vacuum pump 12. With this structure, the diluent gas G2 can be heated to a predetermined temperature by effectively utilizing compression heat in the vacuum pump 12, exhaust heat from a housing of the vacuum pump 12 due to the compression heat, or heat generated from a motor, or further by effectively utilizing a heater installed in the vacuum pump 12, or the like. Thus, since the temperature of the diluent gas G2 sent from the diluent gas source through the diluent gas introduction pipe 24 does not need to be raised to the predetermined temperature or higher when being supplied, temperature control at the diluent gas source is reduced.

[0045] Further, in the above example, a case has been described in which the pipe having the vacuum heat insulating pipe structure is used for the gas exhaust pipe 15, but a structure may be adopted in which itis used for both the gas exhaust pipe 15 and the diluent gas introduction pipe 24 .

[0046] Further , the present invention can be made in various modi fications or combinations without departing from the spirit of the invention, and it goes without saying that the present invention extends to such modi fications and combinations .

[0047] 10 Semiconductor manufacturing process apparatus11 Process chamber12 Vacuum pump13 Exhaust gas detoxi f ication apparatus14 Gas exhaust pipe15 Gas exhaust pipe ( Gas pipe )16 Flange17 O-ring18 Clamp material19 Inner pipe20 Outer pipe21 Vacuum layer22 Vacuum suction port23 Sealing plug24 Diluent gas introduction pipeG1 Exhaust gasG2 Diluent gasG3 Mixed gas

Claims

CLAIMS

1. A vacuum exhaust system comprising: a vacuum pump configured to suck and discharge an exhaust gas discharged from a process chamber; a gas pipe for receiving the exhaust gas discharged from the vacuum pump and having a vacuum heat insulating pipe structure with a vacuum between an inner pipe, through which the exhaust gas discharged from the vacuum pump passes, and an outer pipe surrounding the inner pipe; and a diluent gas introduction portion configured to introduce a diluent gas for heating the exhaust gas in the inner pipe so as to maintain the exhaust gas in a gaseous state in the inner pipe.

2. The vacuum exhaust system according to claim 1, wherein the gas pipe has a sealed structure with a vacuum between the inner pipe and the outer pipe .

3. The vacuum exhaust system according to claim 1, wherein the diluent gas is heated by the vacuum pump.

4. The vacuum exhaust system according to claim 1, wherein the gas pipe is provided to be connected between an exhaust port of the vacuum pump and equipment for detoxification treatment of the exhaust gas discharged from the vacuum pump.

5. The vacuum exhaust system according to claim 1, wherein the vacuum pump includes an exhaust port connected to the gas pipe and having a vacuum heat insulating pipe structure with a vacuum between an inner pipe, through which the exhaust gas discharged from the vacuum pump passes, and an outer pipe surrounding the inner pipe.

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