JP2021042697A - Exhaust system and vacuum pump - Google Patents

Abstract

To provide an exhaust system which can prevent interference between a driving part of a vacuum valve and a vacuum pump and achieve a high flow rate while inhibiting increase in the size of the exhaust system.SOLUTION: An exhaust system includes: a vacuum valve 10 having a valve body casing 13 having a valve intake port 130 and a valve exhaust port 131 formed, a valve body 11 which opens or closes a passage 132, and a driving part 14 which drives the valve body 11 to open or close the valve body 11; and a vacuum pump 20 having a pump rotor 2 which is rotationally driven and a pump casing 8 which is provided with an intake port flange 80 connected to the valve exhaust port 131 and which is formed coaxially with the pump rotor 2. The pump casing 8 has an outer diameter D2 larger than an outer diameter D1 of the intake port flange 80, and a center axis J2 of the intake port flange 80 is arranged eccentrically from a center axis J1 of the pump rotor 2 in a direction of the driving part 14.SELECTED DRAWING: Figure 1

Description

The present invention relates to an exhaust system and a vacuum pump.

In the semiconductor manufacturing process, in the process of processing in a high vacuum process chamber such as dry etching and CVD, the turbo molecule is used as a means to exhaust the gas in the process chamber to form a constant high vacuum degree. A vacuum pump such as a pump is used. Further, between the turbo molecular pump and the process chamber, an automatic pressure regulation type vacuum valve called an APC valve is installed in order to adjust the pressure inside the process chamber to an arbitrary pressure during the process (for example, Patent Document). 1).

In recent years, a large flow rate process for flowing a large amount of gas has been increasing, and a large flow rate exhaust performance is also required for a turbo molecular pump. Therefore, for example, as shown in FIG. 13 of Patent Document 1, by using a turbo molecular pump having a shape in which the outer diameter of the rotor is increased and the outer diameter of the pump casing is narrowed as it approaches the intake flange. It corresponds to a large flow rate.

Japanese Unexamined Patent Publication No. 2018-200042

The vacuum valve attached to the vacuum chamber disclosed in Patent Document 1 has a valve body for accommodating the valve body, a motor for driving the valve body, and a motor casing provided with the motor. It is provided so as to project from the valve body accommodating the valve body toward the vacuum pump side. In such a configuration, it is necessary to set the rotor outer diameter so that the motor casing does not interfere with the pump casing. As a result, there is a limit to the increase in the size of the outer shape of the rotor, and there is a problem that it cannot sufficiently cope with the increase in the flow rate of the exhaust system.

The exhaust system according to the aspect of the present invention includes a valve casing in which a valve intake port and a valve exhaust port are formed, a valve body that opens and closes a flow path between the valve intake port and the valve exhaust port, and the valve body. A vacuum valve having a drive unit that opens and closes, a rotor that is driven to rotate, and a vacuum pump that has an intake flange connected to the valve exhaust port and has a casing formed coaxially with the rotor. The outer diameter of the casing is larger than the outer diameter of the intake port flange, and the central axis of the intake port flange is eccentric with respect to the central axis of the rotor in the direction of the drive unit.
The vacuum pump according to the aspect of the present invention is a vacuum pump used in the vacuum exhaust system, and includes a rotor that is driven to rotate and a casing provided with an intake flange and formed coaxially with the rotor. The outer diameter of the casing is larger than the outer diameter of the intake port flange, and the central axis of the intake port flange is eccentric with respect to the central axis of the rotor.

According to the present invention, it is possible to prevent interference between the drive unit of the vacuum valve and the vacuum pump, and to increase the flow rate while suppressing the increase in size of the exhaust system.

FIG. 1 is a diagram showing an example of an exhaust system. FIG. 2 is a view taken along the arrow A of FIG. FIG. 3 is a view of the vacuum valve as viewed from the vacuum pump side. FIG. 4 is a diagram showing a comparative example. FIG. 5 is a diagram showing a second comparative example.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an example of an exhaust system 1. The exhaust system 1 includes a vacuum valve 10 and a vacuum pump 20. In the exhaust system 1 shown in FIG. 1, a magnetic levitation type turbo molecular pump is used as the vacuum pump 20. In FIG. 1, the vacuum valve 10 is shown in appearance, and the vacuum pump 20 is shown in cross-sectional view.

The vacuum valve 10 includes a valve body casing 13 in which the valve body 11 is housed, and a drive unit 14 provided with a valve motor 12 for opening and closing the valve body 11. The drive unit 14 is provided so as to project from the outer wall surface of the valve body casing 13 on the side where the valve exhaust port 131 is formed. The valve body casing 13 is formed with a valve exhaust port 131 and a valve intake port 130 provided on the side opposite to the valve exhaust port 131. The valve intake port 130 and the valve exhaust port 131 are communicated with each other by a flow path 132. When the valve body 11 is opened and closed by the valve motor 12, the amount of the valve body 11 inserted into the flow path 132, that is, the valve opening degree changes, and the conductance of the vacuum valve 10 changes.

The vacuum pump 20 is connected to a valve exhaust port 131 provided on the exhaust side of the vacuum valve 10. The vacuum pump 20 is a pump rotor 2 in which a plurality of rotary blade stages 2A and a rotor cylindrical portion 2B are formed, and a plurality of fixed parts alternately arranged with respect to a plurality of rotary blade stages 2A arranged vertically in the rotor axial direction. A blade stage 4A and a screw stator 4B provided on the outer peripheral side of the rotor cylindrical portion 2B are provided. When the pump rotor 2 is rotated at high speed by the motor 7, gas is exhausted from the intake side to the exhaust side of the vacuum pump 20. In the present embodiment, the central axis J2 of the intake port flange 80 of the vacuum pump 20 is eccentric with respect to the central axis J1 of the pump rotor 2 by an eccentric amount E.

The pump rotor 2 is fastened to a shaft 5 magnetically levitated and supported by magnetic bearings 9a, 9b, 9c. The shaft 5 is rotationally driven by the motor 7. When the magnetic bearings 9a to 9c are not operating, the shaft 5 is supported by the mechanical bearings 3a and 3b. The mechanical bearings 3a and 3b, the magnetic bearings 9a to 9c, and the motor stator of the motor 7 are provided on the base 6. The base 6 is provided with an exhaust port 60. Although not shown, a back pump is connected to the exhaust port 60.

A pump rotor 2 and a plurality of fixed wing stages 4A are housed in the base 6, and a pump casing 8 provided with an intake flange 80 is fixed. When the pump rotor 2 is rotated at high speed by the motor 7, the exhaust action of the turbo pump stage composed of a plurality of rotary blade stages 2A and the fixed blade stage 4A and the exhaust of the drag pump stage composed of the rotor cylindrical portion 2B and the screw stator 4B are performed. Action and occurs. As a result, the gas molecules flowing from the valve intake port 130 side of the vacuum valve 10 to the intake port flange 80 via the flow path 132 are exhausted to the exhaust side of the vacuum pump 20 by the path shown by the broken line arrow R1. It is exhausted to the outside of the pump by a back pump (not shown) connected to the exhaust port 60.

FIG. 2 is a view taken along the arrow A of FIG. Further, FIG. 3 is a diagram showing only the vacuum valve 10, and is a diagram when the vacuum pump 20 is removed in the view taken along the line A shown in FIG. 2. As described above, the drive unit 14 is provided so as to project from the outer wall surface (bottom surface) on the valve exhaust port side toward the vacuum pump side, and the drive unit 14 of the vacuum valve 10 and the pump casing 8 of the vacuum pump 20 are connected to each other. The gap size at the closest point is G.

As shown in FIG. 3, the valve motor 12 provided in the drive unit 14 drives the valve body 11 to a desired opening degree between the position where the opening degree is 0% and the position where the opening degree is 100%. The valve intake port 130 and the valve exhaust port 131 of the vacuum valve 10 have a flange type with the same nominal diameter, and of course, the vacuum pump 20 connected to the valve exhaust port 131 also has the same name as the valve exhaust port 131. A vacuum pump having a diameter intake valve flange 80 is used. That is, the valve intake port 130, the valve exhaust port 131, and the intake port flange 80 have the same outer diameter D1.

(Eccentricity E of the intake flange 80)
Next, the eccentricity of the intake port flange 80 will be described. FIG. 4 is a diagram showing a comparative example, and shows a case where a vacuum pump 20C different from the vacuum pump 20 shown in FIG. 1 is connected to the vacuum valve 10. The vacuum pump 20C is configured such that the intake flange 80 of the pump casing 8C is coaxial with the pump rotor 2C, as in the case of the conventional turbo molecular pump. The outer diameter of the pump casing 8C is the same as the outer diameter D1 of the intake flange 80. Therefore, the gap dimension between the pump casing 8C and the drive unit 14 of the vacuum valve 10 is the same dimension G as in the case of FIG.

The exhaust system 1 of the present embodiment is used, for example, for exhausting a process chamber such as dry etching or CVD in a semiconductor manufacturing process. In a turbo molecular pump, generally, the larger the rotor diameter of the pump rotor on which the turbine blades are formed, the larger the exhaust speed and the flow rate. On the other hand, the diameter of the intake port and the exhaust port of the vacuum valve, that is, the flange nominal diameter, is determined by the flange nominal diameter of the process chamber in which the vacuum valve is mounted. Therefore, it is necessary to increase the flow rate of the turbo molecular pump while keeping the nominal diameter of the intake port flange of the turbo molecular pump the same as the conventional one.

As one of such measures, as shown in FIG. 4, the vacuum pump 20C having the pump rotor 2C whose rotor outer diameter is larger than the inner diameter of the intake port flange, that is, the outer diameter of the pump casing 8C is set to the intake port flange 80. A vacuum pump 20C having a shape that is narrowed down as it approaches is known. A drive unit 14 is provided on the outer wall of the valve body casing 13 on the exhaust port 131 side so as to project.

Therefore, when the gap dimension between the drive unit 14 and the intake port flange 80 of the vacuum pump 20C is G as in the case of FIG. 1, the outer diameter of the pump casing 8C is limited to “D1 + 2G” or less. In FIG. 4, the outer diameter of the pump casing 8C is set to D1, and a gap G is formed between the pump casing 8C and the drive unit 14. As described above, in the case of the vacuum pump 20C shown in FIG. 4, the outer diameter of the pump casing 8C cannot be made larger than that of "D1 + 2G", so that the flow rate cannot be sufficiently increased.

On the other hand, in the case of the vacuum pump 20 shown in FIG. 1, the central axis J2 of the intake port flange 80 is eccentric with respect to the central axis J1 of the pump rotor 2 and the pump casing 8 by the dimension E in the direction of the drive unit 14. .. In other words, the central axis J1 of the pump rotor 2 and the pump casing 8 is eccentric with respect to the central axis J2 of the valve exhaust port 131 of the vacuum valve 10 in the direction opposite to the direction of the drive unit 14 by the dimension E. Since the gap dimension between the pump casing 8 and the drive unit 14 is set to G, which is the same as the gap dimension between the valve exhaust port 131 and the drive unit 14, the outer diameter D2 of the pump casing 8 is “D1 + 2E”. The outer diameter D2 of the pump casing 8 can be set to a maximum of "D1 + 2E + 2G".

That is, as compared with the vacuum pump 20C shown in FIG. 4, the outer diameter D2 of the pump casing 8 can be set larger than 2E by 2E, and the pump rotor 2 having a larger outer diameter is adopted to increase the flow rate. be able to. In this case, the outer diameter of the pump rotor 2 is determined from the required flow rate, and the eccentricity E that the pump casing 8 does not interfere with the drive unit 14 may be set according to the outer diameter.

FIG. 5 is a diagram showing a second comparative example. In FIG. 5, the dimension under the neck of the intake port flange 80 is set large so that the distance from the intake port flange 80 to the upper end of the pump rotor 2 is increased to prevent interference between the pump casing 8 and the drive unit 14. ing. However, in the case of the second comparative example, even if the flow rate can be increased while preventing interference, another problem arises that the dimension of the exhaust system 1 in the pump axial direction becomes too large.

It will be understood by those skilled in the art that the plurality of exemplary embodiments and modifications described above are specific examples of the following embodiments.

[1] The exhaust system according to one embodiment includes a valve casing in which a valve intake port and a valve exhaust port are formed, a valve body that opens and closes a flow path between the valve intake port and the valve exhaust port, and the valve. A vacuum valve having a drive unit that opens and closes the body, a rotor that is driven to rotate, and a vacuum pump that has a casing provided with an intake flange connected to the valve exhaust port and formed coaxially with the rotor. The outer diameter of the casing is larger than the outer diameter of the intake port flange, and the central axis of the intake port flange is eccentric with respect to the central axis of the rotor in the direction of the drive unit.

For example, as shown in FIG. 1, the outer diameter D2 of the pump casing 8 is larger than the outer diameter D1 of the intake port flange 80, and the central axis J2 of the intake port flange 80 is relative to the central axis J1 of the pump rotor 2. By eccentricity in the direction of the drive unit 14, even when the outer diameter D2 of the pump casing 8 is larger than "D1 + 2G", it is possible to prevent the pump casing 8 from interfering with the drive unit 14. Since the outer diameter D2 of the pump casing 8 can be made larger than that of "D1 + 2G", a larger pump rotor 2 can be adopted, and even if the vacuum valves 10 are the same, the flow rate of the exhaust system 1 can be increased. ..

[2] In the exhaust system according to the above [1], the drive unit is provided so as to project from the outer wall surface of the valve casing in which the valve exhaust port is formed, and has an outer diameter of the intake port flange. Assuming that D1, the outer diameter of the casing is D2, and the gap between the intake port flange connected to the valve exhaust port and the drive unit is G, the amount of eccentricity of the central axis of the intake port flange is "(D2- It is larger than "D1) / 2-G" and less than or equal to "(D2-D1) / 2".

For example, in the exhaust system 1 of FIG. 1, the eccentricity E is set to {(D2-D1) /2-G} <E≤{(D2-D1) / 2}. FIG. 1 shows the case of E = (D2-D1) / 2. Since the drive unit 14 is not provided inside the outer circumference of the valve exhaust port 131, the eccentricity E may be at most (D2-D1) / 2, and it is not necessary to eccentricize more than that. Of course, when the eccentricity E is "(D2-D1) / 2-G" or less, the pump casing 8 interferes with the drive unit 14.

[3] A vacuum pump used in the vacuum exhaust system according to the above [1] or [2], the rotor being rotationally driven, and a casing provided with an intake flange and formed coaxially with the rotor. , The outer diameter of the casing is larger than the outer diameter of the intake port flange, and the central axis of the intake port flange is eccentric with respect to the central axis of the rotor.

For example, as shown in FIG. 1, since the central axis J2 of the intake port flange 80 of the vacuum pump 20 is eccentric with respect to the central axis J1 of the pump rotor 2, the vacuum pump 20 is mounted on the valve exhaust port 131 of the vacuum valve 10. The vacuum pump mounted on the vacuum valve 10 is fixed so that the central axis J1 of the pump rotor 2 is eccentric to the central axis J2 of the intake port flange 80 in the direction opposite to that of the drive unit 14. Interference between the pump casing 8 of 20 and the drive unit 14 can be avoided.

The present invention is not limited to the above-mentioned contents. Other aspects conceivable within the scope of the technical idea of the present invention are also included within the scope of the present invention. For example, if the casing provided with the intake flange is a vacuum pump coaxial with the pump rotor, the application is not limited to the turbo molecular pump.

1 ... Exhaust system, 13 ... Valve body casing, 2,2C ... Pump rotor, 8,8C ... Pump casing, 10 ... Vacuum valve, 11 ... Valve body, 14 ... Drive unit, 20, 20C ... Vacuum pump, 80 ... Intake Mouth flange, 130 ... Valve intake port, 131 ... Valve exhaust port, 132 ... Flow path, D1, D2 ... Outer diameter, E ... Eccentricity, J1, J2 ... Central axis

Claims (3)

A vacuum valve having a valve casing in which a valve intake port and a valve exhaust port are formed, a valve body that opens and closes a flow path between the valve intake port and the valve exhaust port, and a drive unit that opens and closes the valve body. When,
A rotor driven by rotation and a vacuum pump provided with an intake flange connected to the valve exhaust port and having a casing formed coaxially with the rotor.
An exhaust system in which the outer diameter of the casing is larger than the outer diameter of the intake port flange, and the central axis of the intake port flange is eccentric with respect to the central axis of the rotor in the direction of the drive unit. In the exhaust system according to claim 1,
The drive unit is provided so as to project toward the vacuum pump side from the outer wall surface of the valve casing in which the valve exhaust port is formed.
Assuming that the outer diameter of the intake port flange is D1, the outer diameter of the casing is D2, and the gap between the intake port flange connected to the valve exhaust port and the drive unit is G.
An exhaust system in which the amount of eccentricity of the central axis of the intake port flange is larger than "(D2-D1) / 2-G" and less than or equal to "(D2-D1) / 2". A vacuum pump used in the exhaust system according to claim 1 or 2.
Rotationally driven rotor and
An intake flange is provided, and a casing formed coaxially with the rotor is provided.
A vacuum pump in which the outer diameter of the casing is larger than the outer diameter of the intake port flange, and the central axis of the intake port flange is eccentric with respect to the central axis of the rotor.

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