Evacuation system

Abstract

To provide an evacuation system capable of sending an exhaust gas and a diluent gas to a predetermined place without lowering a temperature of the exhaust gas and the diluent gas as much as possible in a state where a constant temperature is maintained.SOLUTION: A structure includes: a gas exhaust pipe 14 that is connected to a rear stage of a vacuum pump 12, and has a vacuum insulation piping structure in which a vacuum layer 21 between an inner pipe 19 passing through a used gas G1 exhausted from the vacuum pump 12 and an outer pipe 20 externally attached to the inner pipe 19 exists; and a dilute gas introduction pipe 24 for introducing a dilution gas G2 for heating the used gas G1 to the inner pipe 19 so as to maintain a gas state of the used gas G1 in the gas exhaust pipe 14.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vacuum pumping system that uses a vacuum pump. [Background technology]

[0002] For example, in semiconductor manufacturing processes, chemical vapor deposition (CVD) and dry etching processes are performed to deposit semiconductor, insulator, metal films, etc. on semiconductor wafers using chemical vapor reactions, and various gases, such as silane (SiH4) gas, are used in the process chambers. The used gases discharged from the process chambers are sucked in by a dry pump or the like and further introduced into a detoxification device via a gas exhaust pipe, where they are detoxified (see, for example, Patent Document 1).

[0003] In such semiconductor manufacturing processes, when the spent gas cools, it solidifies as a film or powder and adheres to the exhaust piping other than the process chamber, the inside of the dry pump, and the abatement device, and accumulates, causing pipe blockage. This requires frequent maintenance. Furthermore, when a liquid process gas is used, the spent gas re-liquefies in the exhaust piping other than the process chamber, the inside of the dry pump, and the abatement device, making maintenance difficult and requiring separate measures.

[0004] As part of this maintenance, in conventional semiconductor manufacturing processes, cleaning gases such as CIF3 (chlorine trifluoride), NF3 (nitrogen trifluoride), and HCl (hydrogen chloride) are periodically introduced into the process chamber at each location where a film is formed on a semiconductor wafer, depending on the type of product that adheres to the process, to decompose and discharge the adhered material, thereby cleaning the reaction chamber, exhaust piping, dry pump, and detoxification device of the semiconductor processing equipment (see, for example, Patent Document 1).

[0005] Generally, the higher the temperature of the used gas and cleaning gas is, 100° C. or higher, the more efficiently the adhering matter can be decomposed and discharged.

[0006] Therefore, it is preferable that the used gas and cleaning gas (hereinafter collectively referred to as "used exhaust gas") that travel from the process chamber through the dry pump to the detoxification device located several meters away from the dry pump be kept at a high temperature of 100°C or higher before being introduced into the detoxification device.

[0007] Therefore, a method has been proposed in which a dilution gas heated to about 300°C is added to the spent exhaust gas discharged from the dry pump between the dry pump and the detoxification device, and mixed with the spent gas, thereby heating the spent gas to 150 to 200°C and introducing it into the detoxification device (see, for example, Patent Document 2).

[0008] In Patent Document 2, an electric heating wire is used as the heat source for heating the diluent gas to a predetermined temperature.

[0009] Also, a method has been proposed in which heat generated by a dry pump is used as a heat source for heating the dilution gas to be introduced into the detoxification device to a predetermined temperature (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 3456933 [Patent Document 2] Japanese Patent Application Publication No. 4-330388 [Patent Document 3] Patent No. 6418838 Summary of the Invention [Problem to be solved by the invention]

[0011] In the conventional methods shown in Patent Documents 2 and 3, the diluted gas and exhaust gas heated to a predetermined temperature are introduced into a detoxification device or the like through a general gas piping. Therefore, the diluted gas and exhaust gas are affected by the operating environment of the system and their temperatures decrease while passing through the piping, making it difficult to maintain the predetermined temperature.

[0012] The present invention has been made in consideration of these conventional problems, and a technical problem that must be solved is to provide a vacuum pumping system that can send exhaust gas and dilution gas to a specified location while maintaining a constant temperature without lowering their temperatures as much as possible, and the present invention aims to solve this problem. [Means for solving the problem]

[0013] The present invention has been proposed to achieve the above-mentioned object, and the invention described in claim 1 provides a vacuum exhaust system comprising: a vacuum pump that sucks in and exhausts exhaust gas discharged from a process chamber; a gas pipe connected downstream of the vacuum pump and having a vacuum insulated piping structure in which a vacuum is formed between an inner pipe through which the exhaust gas discharged from the vacuum pump passes and an outer pipe attached to the inner pipe; and a dilution gas introduction section that introduces a dilution gas into the inner pipe to heat the exhaust gas so that the exhaust gas remains in a gaseous state within the inner pipe.

[0014] According to this configuration, exhaust gas and dilution gas are supplied to a predetermined location through the inner pipe of a gas pipe having a vacuum insulation structure, in which a vacuum is created between the inner pipe and the outer pipe attached to the inner pipe, via a dilution gas heated to maintain the exhaust gas in a gaseous state. Therefore, in a gas pipe having a vacuum insulation structure in which a vacuum layer is created between the inner pipe and the outer pipe, heat transfer between the inner pipe and the outer pipe is blocked by the vacuum layer, so the exhaust gas and dilution gas passing through the inner pipe are sent to a predetermined location through the inner pipe at the same temperature, i.e., the temperature at which the exhaust gas maintains its gaseous state, without losing heat to the outer pipe. This facilitates thermal control of the exhaust gas and dilution gas, and improves the thermal efficiency of the exhaust gas and dilution gas in a vacuum exhaust system using gas pipes with this vacuum insulation structure.

[0015] The invention described in claim 2 provides a vacuum exhaust system in the configuration described in claim 1, wherein the gas piping is configured as a sealed structure in which a vacuum is created between the inner pipe and the outer pipe.

[0016] According to this configuration, a sealed structure is formed between the inner tube and the outer tube, and therefore once a sealed vacuum structure is formed between the inner tube and the outer tube, the vacuum state can be easily maintained thereafter, making it easy to manage the vacuum state.

[0017] A third aspect of the present invention provides the vacuum pumping system of the first aspect, wherein the dilution gas is heated by the vacuum pump.

[0018] According to this configuration, the dilution gas can be heated to a predetermined temperature by effectively utilizing the heat of compression within the pump, the heat exhausted from the housing due to the heat of compression, and the heat generated by the motor.

[0019] The invention described in claim 4 provides a vacuum exhaust system having the configuration described in claim 1, wherein the gas piping is connected between an exhaust port of the vacuum pump and equipment for detoxifying the exhaust gas discharged from the vacuum pump.

[0020] With this configuration, the temperature of the exhaust gas discharged from the exhaust port of the vacuum pump and heading to the detoxification equipment can be maintained at a temperature suitable for detoxification within the equipment, and the exhaust gas can be sent to the equipment, which is expected to improve the efficiency of the detoxification treatment of the exhaust gas in the detoxification treatment equipment.

[0021] The invention described in claim 5 provides a vacuum exhaust system having the configuration described in claim 1, wherein the vacuum pump is connected to the gas piping and includes an exhaust port having a vacuum insulated piping structure in which a vacuum is created between an inner pipe through which the exhaust gas discharged from the vacuum pump passes and an outer pipe attached to the inner pipe.

[0022] According to this configuration, the exhaust port of the vacuum pump itself has a vacuum insulation structure in which a vacuum is created between the inner pipe and the outer pipe attached to the inner pipe. Therefore, in an exhaust port having a vacuum insulation structure in which a vacuum is created between the inner pipe and the outer pipe, heat transfer between the inner pipe and the outer pipe is blocked by the vacuum layer. Therefore, the exhaust gas and dilution gas passing through the inner pipe of the exhaust port are sent to a predetermined location through the inner pipe at the same temperature, i.e., at a temperature at which the exhaust gas maintains its gaseous state, without losing heat to the outer pipe. This makes it easier to control the heat of the exhaust gas and dilution gas in a vacuum exhaust system using gas piping with this vacuum insulation structure, and further improves the thermal efficiency of the exhaust gas and dilution gas. [Effects of the Invention]

[0023] According to the present invention, by using gas piping with a vacuum insulation structure in which a vacuum is created between the inner and outer pipes, the exhaust gas and dilution gas passing through the inner pipe can be sent to a predetermined location through the inner pipe at the same temperature, i.e., at a temperature at which the exhaust gas remains in a gaseous state, without losing heat to the outer pipe. This makes it easy to manage the thermal control of the exhaust gas and dilution gas in the vacuum exhaust system, and also improves the thermal efficiency of the exhaust gas and dilution gas. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a schematic diagram showing a configuration of a main part of a semiconductor manufacturing process device using a vacuum exhaust system according to an embodiment of the present invention; [Figure 2] 1A and 1B show an example of gas exhaust piping used in the semiconductor manufacturing process equipment, in which (a) is a schematic cross-sectional view of the gas exhaust piping taken along its longitudinal direction, and (b) is a cross-sectional view taken along the line AA in (a). [Figure 3] FIG. 1 is a diagram showing an example of a sublimation temperature curve. [Figure 4] FIG. 10 is a diagram showing an example of an evaluation result. [Figure 5] FIG. 10 is a schematic diagram showing a modified example of the vacuum exhaust system according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] In order to achieve the object of the present invention to provide a vacuum exhaust system that can send exhaust gas and dilution gas to a predetermined location while maintaining a constant temperature without lowering their temperatures as much as possible, the present invention has been realized by providing a configuration that includes a vacuum pump that sucks in and exhausts exhaust gas discharged from a process chamber, a gas pipe that is connected downstream of the vacuum pump and has a vacuum insulated piping structure in which a vacuum is created between an inner pipe through which the exhaust gas discharged from the vacuum pump passes and an outer pipe that is fitted onto the inner pipe, and a dilution gas inlet section that introduces a dilution gas into the inner pipe to heat the exhaust gas so that the exhaust gas remains in a gaseous state within the pipe. [Example]

[0026] An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. In the following embodiment, when the number, value, amount, range, etc. of components is mentioned, the number is not limited to the specific number, and may be more or less than the specific number, unless otherwise specified or when it is clearly limited to a specific number in principle.

[0027] Furthermore, when referring to the shape or positional relationship of components, etc., it includes things that are substantially similar or approximate to those shapes, etc., unless otherwise specified or when it is clearly considered otherwise in principle.

[0028] In addition, the drawings may exaggerate characteristic parts to make the features easier to understand, and the dimensional proportions of the components may not be the same as in reality. In addition, in cross-sectional views, hatching of some components may be omitted to make the cross-sectional structure of the components easier to understand.

[0029] In the following description, expressions indicating directions such as up, down, left, and right are not absolute, but are appropriate when each part of the semiconductor manufacturing process of the present invention is in the illustrated position, but if the position changes, they should be interpreted accordingly. Furthermore, the same symbols are used to refer to the same elements throughout the description of the embodiments.

[0030] 1 is a schematic diagram showing the configuration of the main parts of a semiconductor manufacturing process apparatus 10 that uses a vacuum pumping system according to an embodiment of the present invention. The overall configuration of the semiconductor manufacturing process apparatus 10 will be described in brief with reference to FIG.

[0031] The semiconductor manufacturing process equipment 10 shown in FIG. 1 includes a process chamber 11 in which semiconductor wafers are processed and treated, a vacuum pump 12, and an exhaust gas abatement system 13. For example, a process gas for the semiconductor wafer processing or a cleaning gas for the cleaning process is supplied to the process chamber 11. The process gas may be, for example, silane (SiH4) gas, and the cleaning gas may be, for example, CIF3 (chlorine trifluoride), NF3 (nitrogen trifluoride), or HCl (hydrogen chloride). After the processing in the process chamber 11 is completed, the process gas or cleaning gas in the process chamber 11 is sent from the process chamber 11 to the vacuum pump 12 via a gas exhaust pipe 14. Hereinafter, these process gases and cleaning gases are collectively referred to as "used exhaust gas G1." The used exhaust gas G1 sent to the vacuum pump 12 is gradually pressurized to near atmospheric pressure inside the vacuum pump 12 and heated to its sublimation temperature, and then discharged into the gas exhaust pipe 15 and sent through the inside of the gas exhaust pipe 15 to the exhaust gas detoxification device 13. Then, the used exhaust gas G1 is rendered harmless in the exhaust gas detoxification device 13 and then discharged into the atmosphere.

[0032] Furthermore, in order to prevent the temperature of the spent exhaust gas G1 from cooling below the sublimation temperature during the time that the spent exhaust gas G1 discharged from the vacuum pump 12 into the gas exhaust piping 15 is rendered harmless inside the exhaust gas detoxification device 13, a dilution gas G2 heated to a high temperature above the sublimation temperature is introduced into the gas exhaust piping 15 from an arbitrary position in the gas exhaust piping 15, and the spent exhaust gas G1 and the dilution gas G2 are mixed and sent to the exhaust gas detoxification device 13 while maintaining a high temperature (above the sublimation temperature). Note that the dilution gas G2 in this embodiment is, for example, a gas such as N2 (nitrogen), NH4Cl (ammonium chloride), or AlCl3 (aluminum chloride).

[0033] In the semiconductor manufacturing process equipment 10 shown in Figure 1, a gas exhaust pipe 15, which is one embodiment of the present invention, is used as a gas pipe that is less likely to lower in temperature than a mixed gas G3 of used exhaust gas G1 and dilution gas G2 that flows from a vacuum pump 12 to an exhaust gas detoxification device 13.

[0034] FIG. 2 shows an example of a gas exhaust pipe 15 used in a semiconductor manufacturing process device, where 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 cross-sectional view taken along the line AA in FIG. 2(a).

[0035] The gas exhaust pipe 15 shown in Figure 2 is formed by connecting multiple pipes in the axial direction to form a single pipe. Flanges 16 are provided at each connection point, and O-rings 17 are interposed between the flanges 16 and the pipes, and the outside of the flanges 16 is fastened with clamps 18 to form a continuous single pipe structure.

[0036] More specifically, the gas exhaust pipe 15 is connected to the rear of the vacuum pump 12 or to the gas outlet (exhaust port), and has a double-pipe structure including an inner pipe 19 through which the used exhaust gas G1 exhausted from the vacuum pump 12 passes, and an outer pipe 20 that covers the entire outer peripheral surface of the inner pipe 19 and is attached to the inner pipe 19, and further has a vacuum insulation pipe structure with a vacuum layer provided between the inner pipe 19 and the outer pipe 20. One end of the inner pipe 19 of the gas exhaust pipe 15 is connected to a gas outlet (not shown) of the vacuum pump 12, and the other end is connected to an exhaust gas inlet (not shown) of the exhaust gas abatement device 13. Note that both ends of the outer pipe 20, which forms a vacuum layer 21 with the inner pipe 19, are tightly connected to the outer peripheral surface of the inner pipe 19, and the gap between the inner pipe 19 and the outer pipe 20, i.e., the location where the vacuum layer 21 is formed, is a space formed as an airtight structure.

[0037] The gas exhaust pipe 15 is provided with a vacuum port 22 that leads to the gap between the inner pipe 19 and the outer pipe 20, i.e., the space forming the vacuum layer 21. After the air inside the space formed between the inner pipe 19 and the outer pipe 20 is removed to form the vacuum layer 21, the vacuum port 22 is closed with a sealing plug 23. The space forming the vacuum layer 21 does not have to be a continuous space from one end of the gas exhaust pipe 15 to the other, but may be divided into multiple chambers. If the space is divided, a vacuum port 22 and a sealing plug 23 are provided for each divided section. The exhaust port (not shown) of the vacuum pump 12 to which the gas exhaust pipe 15 is connected preferably has a vacuum insulated piping structure in which a vacuum is created between the inner pipe through which the used exhaust gas G1 passes and the outer pipe exteriorly attached to the inner pipe, similar to the gas exhaust pipe 15.

[0038] Furthermore, the gas exhaust pipe 15 is provided with a dilution gas introduction pipe 24 as a dilution gas introduction section that connects from the outside of the outer pipe 20 to the inside of the inner pipe 19. One end of the gas exhaust pipe 15 is connected to a dilution gas source, and a dilution gas G2 is introduced into the inner pipe 19 through the dilution gas introduction pipe 24.

[0039] The temperature of the diluent gas G2 introduced into the inner tube 19 from the diluent gas source through the diluent gas introduction pipe 24 varies depending on the temperature of the spent exhaust gas G1. The diluent gas G2 is heated to a temperature sufficient to maintain the spent exhaust gas G1 in a gaseous state, i.e., a temperature higher than the sublimation temperature of the spent exhaust gas G1, and is then introduced into the inner tube 19, whereby the spent exhaust gas G1 can be instantaneously heated to a temperature above the sublimation temperature. The temperature is determined, for example, with reference to a table of sublimation temperature curves shown in Figure 3. In Figure 3, when the diluent gas G2 is NH4Cl (ammonium chloride), it is heated to approximately 340°C, and when it is AlCl3 (aluminum chloride), it is heated to approximately 200°C before being introduced.

[0040] Next, the operation of the semiconductor manufacturing process apparatus 10 will be described. Spent exhaust gas G1 passes through the vacuum pump 12 from the process chamber 11, is heated to a high temperature by compression within the vacuum pump 12, and is discharged in a high-temperature gaseous state into the inner pipe 19 of the gas exhaust piping 15. The gas is then sent toward the exhaust gas detoxification device 13. The gas is mixed with dilution gas G2, which is hotter than the spent exhaust gas G1 and is fed from the dilution gas introduction pipe 24 via the inner pipe 19, which is provided at an arbitrary position in the gas exhaust piping 15. The mixed gas G3 is then heated to a temperature higher than the spent exhaust gas G1 (above the sublimation temperature), and the mixed gas G3 containing the spent exhaust gas G1 is introduced into the exhaust gas detoxification device 13 while maintained in a gaseous state. The mixed gas G3 containing the spent exhaust gas G1 introduced into the exhaust gas detoxification device 13 is detoxified by the exhaust gas detoxification device 13 and then discharged into the atmosphere.

[0041] Therefore, in the semiconductor manufacturing process equipment 10 of this embodiment, a gas pipe, i.e., a gas exhaust pipe 15, is used, which has a vacuum insulation structure with a vacuum layer 21 between the inner pipe 19 and the outer pipe 20 attached to the inner pipe 19, and a dilution gas G2 heated to maintain the spent exhaust gas G1 in a gaseous state is passed through the inner pipe 19 of the gas exhaust pipe 15, through which the spent exhaust gas G1 passes, and the mixed gas G3 of the spent exhaust gas G1 and the dilution gas G2 is mixed and sent to a specified location, the exhaust gas detoxification device 13. Here, the gas exhaust pipe 15 has a vacuum insulation structure with a vacuum layer 21 between the inner pipe 19 and the outer pipe 20, and heat transfer between the inner pipe 19 and the outer pipe 20 is blocked by the vacuum layer 21. Therefore, the mixed gas G3, which is a mixture of the used exhaust gas G1 and the dilution gas G2 passing through the inner pipe 19, passes through the inner pipe 19 without losing heat to the outer pipe 20 and is sent to the specified location, i.e., the exhaust gas abatement device 13, while maintaining the same temperature, i.e., the temperature at which the used exhaust gas G1 maintains its gaseous state. As a result, in the semiconductor manufacturing process equipment 10 using the gas exhaust pipe 15 with this vacuum insulation structure, thermal control (prevention of temperature drops) is easier and thermal efficiency can be improved.

[0042] FIG. 4 shows the results of a comparison between the gas exhaust pipe 15 of this embodiment and a conventional piping structure. In this experiment, a 2.5-meter-long straight pipe was used, gas at 250°C was flowed from the inlet, and the temperature at the outlet was measured. (A) in FIG. 4 shows the temperature drop when a single pipe was used. The drop was approximately 120°C, resulting in a 50% loss. (B) in FIG. 4 shows the temperature drop when a single pipe was used with insulation attached to its outer periphery. The drop was approximately 75°C, resulting in a 25% loss. (C) in FIG. 4 shows the temperature drop when the gas exhaust pipe 15 of this embodiment, which has a vacuum layer 21 between the inner pipe 19 and the outer pipe 20, was used. The drop was approximately 25°C, resulting in a 10% loss. These results demonstrate that the gas exhaust pipe 15 of this embodiment reduces the temperature drop by approximately 10 to 20% compared to the conventional pipe, improving thermal efficiency.

[0043] In the semiconductor manufacturing process apparatus 10 of the above embodiment, a structure has been disclosed in which the dilution gas introduction pipe 24 is connected immediately after the gas exhaust pipe 15 leading to the outside of the vacuum pump 12, and the dilution gas G2 is introduced into the inner pipe 19 of the gas exhaust pipe 15 through the dilution gas introduction pipe 24. However, instead of this structure, for example, as shown in FIG. 5, a structure may be adopted in which the dilution gas introduction pipe 24 is connected to the inside of the vacuum pump 12, and the dilution gas G2 sent from the dilution gas source through the dilution gas introduction pipe 24 is mixed with the used exhaust gas G1 inside the vacuum pump 12.

[0044] As described above, the structure for mixing the spent exhaust gas G1 and the dilution gas G2 inside the vacuum pump 12 may further include providing a dilution gas inlet pipe 24 so as to surround the outer periphery of the vacuum pump 12. This structure makes it possible to heat the dilution gas G2 to a predetermined temperature by effectively utilizing the compression heat inside the vacuum pump 12, the exhaust heat from the housing of the vacuum pump 12 due to the compression heat, the heat generated by the motor, and even a heater provided inside the vacuum pump 12. This eliminates the need to raise the temperature of the dilution gas G2 sent from the dilution gas source through the dilution gas inlet pipe 24 above a predetermined temperature before supplying it, thereby reducing the temperature management burden at the dilution gas source.

[0045] In addition, in the above embodiment, a vacuum insulated piping structure is used for the gas exhaust piping 15, but the structure may also be used for both the gas exhaust piping 15 and the dilution gas introduction pipe 24.

[0046] Furthermore, the present invention can be modified or combined in various ways without departing from the spirit of the present invention, and it is natural that the present invention covers such modifications and combinations. [Explanation of symbols]

[0047] 10: Semiconductor manufacturing process equipment 11: Process chamber 12: Vacuum pump 13: Exhaust gas abatement device 14: Gas exhaust piping 15: Gas exhaust piping (gas piping) 16: Flange 17: O-ring 18: Clamp material 19: Inner tube 20:Outer tube 21: Vacuum layer 22: Vacuum outlet 23: Sealing stopper 24: Dilution gas inlet pipe G1: Exhaust gas G2: Dilution gas G3: Mixed gas

Claims

1. a vacuum pump that sucks and discharges exhaust gases discharged from the process chamber; a gas pipe connected to a downstream side of the vacuum pump, the gas pipe having a vacuum insulation pipe structure in which a vacuum is formed between an inner pipe through which the exhaust gas discharged from the vacuum pump passes and an outer pipe exteriorly fitted to the inner pipe; a dilution gas introduction section that introduces a dilution gas into the inner pipe to heat the exhaust gas so that the exhaust gas is maintained in a gaseous state within the inner pipe; A vacuum pumping system comprising:

2. 2. The vacuum pumping system according to claim 1, wherein the gas piping has a sealed structure in which a space between the inner pipe and the outer pipe is evacuated.

3. 2. The vacuum pumping system according to claim 1, wherein the dilution gas is heated by the vacuum pump.

4. 2. The vacuum exhaust system according to claim 1, wherein the gas piping is connected between an exhaust port of the vacuum pump and equipment for detoxifying the exhaust gas discharged from the vacuum pump.

5. 2. The vacuum exhaust system according to claim 1, wherein the vacuum pump is connected to the gas piping and includes an exhaust port having a vacuum insulated piping structure in which a vacuum is created between an inner pipe through which the exhaust gas discharged from the vacuum pump passes and an outer pipe exteriorly attached to the inner pipe.

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