Patent Grant
12158152
This application is a Section 371 National Stage Application of International Application No. PCT/JP2020/019034, filed May 12, 2020, which is incorporated by reference in its entirety and published as WO 2020/230799A1 on Nov. 19, 2020 and which claims priority of Japanese Application No. 2019-092143, filed May 15, 2019.
The present invention relates to a vacuum pump used as a gas exhaust means for a process chamber of a semiconductor manufacturing processing apparatus, a flat panel display manufacturing apparatus, and a solar panel manufacturing apparatus and other vacuum chambers, and a stator component of a thread groove pump portion of the vacuum pump. The present invention is particularly suitable for preventing a backflow of a particle from the vacuum pump toward the vacuum chamber.
Vacuum pumps such as turbomolecular pumps and thread groove pumps are heavily used for exhausting vacuum chambers required to create a high vacuum.
A vacuum pump Z of prior art that constitutes the exhaust system of
Incidentally, in the exhaust system of
There has conventionally existed a means for reducing the number of particles flowing back toward the vacuum chamber CH by controlling the bouncing direction of the particle described above. Specifically, an upper surface 9A of the stator component of the thread groove pump portion PS (specifically, the thread groove pump portion stator 9 that forms a thread groove flow path R for exhausting the gas molecules by facing a cylindrical rotary component 6) is tilted (see the description of paragraph 0019 of Japanese Patent No. 6414401).
However, the particle may be sufficiently small relative to the surface roughness of the upper surface 9A of the thread groove pump portion stator (stator component), such as when the size of the particle is 10−3 times that of the height difference of the unevenness caused by the surface roughness of the upper surface 9A. In this case, the particle that collides with the upper surface 9A of the thread groove pump portion stator (stator component) is irregularly reflected. Therefore, in the conventional configuration in which the upper surface 9A of the thread groove pump portion stator (stator component) is tilted as described above, the bouncing direction of the particle on the upper surface 9A of the thread groove pump portion stator (stator component) cannot be controlled sufficiently, and the number of particles flowing back toward the vacuum chamber CH cannot be reduced effectively.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background.
The present invention was contrived in order to solve the foregoing problems, and an object thereof is to provide a vacuum pump suitable for preventing the backflow of the particle from the vacuum pump toward the vacuum chamber.
In order to achieve the foregoing object, the present invention provides a vacuum pump that include a turbomolecular pump portion exhausting gas molecules by a rotor blade and a stator blade, and a thread groove pump portion provided downstream of the turbomolecular pump portion and exhausting the gas molecules by a thread groove flow path formed by a cylindrical rotary component and a cylindrical stator component provided on an outer periphery of the cylindrical rotary component, wherein a bounce back prevention means for preventing a particle from bouncing from the thread groove pump portion back toward the turbomolecular pump portion is provided downstream of the turbomolecular pump portion.
In the present invention, the bounce back prevention means may be characterized in that an upper surface of the stator component that faces the turbomolecular pump portion is inclined and smooth.
In the present invention, the bounce back prevention means may be structured to include a recess portion in an upper portion of the stator component that faces the turbomolecular pump portion.
In the present invention, the recess portion may be shaped to penetrate the stator component and connected to a particle trapping space.
In the present invention, the recess portion may be positioned near immediately below a gap provided on an outer end side of the rotor blade.
In the present invention, the recess portion may include a smooth surface in at least a part of a surface of the recess portion.
The present invention also provides a stator component of a thread groove pump portion of a vacuum pump, the stator component being provided downstream of a turbomolecular pump portion exhausting gas molecules by a rotor blade and a stator blade, and forming a thread groove flow path with a cylindrical rotary component to exhaust the gas molecules, wherein the stator component includes a bounce back prevention means for preventing a particle from bouncing from the thread groove pump portion back toward the turbomolecular pump portion.
In the present invention, the term “bounce back” means that the particle collides with something and bounce. The term “immediately below the gap” means not only “directly below” the gap but also “immediately below” the gap. The same is true for the foregoing embodiments.
According to the present invention, the bounce back prevention means prevents the particle from bouncing from the thread groove pump portion toward the turbomolecular pump portion. Thus, the present invention can provide a vacuum pump that is suitable for preventing the backflow of the particle from the vacuum pump toward a vacuum chamber in terms of reducing the percentage of the bouncing particle flowing back toward the vacuum chamber upstream of the vacuum pump.
The Summary is provided to introduce a selection of concepts in a simplified form that are further described in the Detail Description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
The best mode for carrying out the present invention is now described hereinafter in detail with reference to the accompanying drawings.
Referring to
The casing 1 has a bottomed cylindrical shape in which a tubular pump case 1A and a bottomed tubular pump base 1B are integrally coupled to each other by fastening bolts in a cylinder axis direction of the pump case 1A and the pump base 1B. An upper end potion of the pump case 1A is opened as an inlet port 2 for sucking gas, and a side surface of a lower end portion of the pump base 1B is provided with an outlet port 3 for exhausting the gas to the outside of the casing 1.
The inlet port 2 is connected to a vacuum chamber that creates a high vacuum, such as a process chamber of a semiconductor manufacturing apparatus, via a pressure adjustment valve, not shown. The outlet port 3 is connected in a communicating manner to an auxiliary pump, not shown.
A cylindrical stator column 4 containing various electrical components is provided in a central part of the pump case 1A. In the vacuum pump P1 of
The cylindrical portion 6 described above is provided outside the stator column 4. The cylindrical portion 6 is in the shape of a cylinder enclosed in the pump case 1A and the pump base 1B and surrounding an outer periphery of the stator column 4.
A rotating shaft 5 (rotor shaft) is provided inside the stator column 4. The rotating shaft 5 is arranged in such a manner that an upper end portion of the same faces the inlet port 2 and a lower end portion thereof faces a bottom surface of the pump base 1B. The rotating shaft 5 is also rotatably supported by magnetic bearings (specifically, two sets of known radial magnetic bearings MB1 and one set of known axial magnetic bearings MB2). Furthermore, a drive motor MO is provided inside the stator column 4, and the rotating shaft 5 is driven by this drive motor MO to rotate about an axis of the rotating shaft 5.
The upper end portion of the rotating shaft 5 protrudes upward from a cylinder upper end surface of the stator column 4, and an upper end of the cylindrical portion 6 is integrally fixed to this protruding upper end portion of the rotating shaft 5 by fastening means such as bolts. The cylindrical portion 6, therefore, is rotatably supported by the magnetic bearings (the radial magnetic bearings MB1, the axial magnetic bearings MB2) via the rotating shaft 5. When the drive motor MO is started in this supported state, the cylindrical portion 6 can rotate integrally with the rotating shaft 5 around a rotation axis thereof. In other words, in the vacuum pump P1 shown in
In the vacuum pump P1 of
Configuration of Turbomolecular Pump Portion PT
A plurality of rotor blades 7 that rotates integrally with the cylindrical portion 6 are provided on an outer peripheral surface of the cylindrical portion 6 at the upstream side from approximately the middle of the cylindrical portion 6, and these rotor blades 7 are arranged radially at predetermined intervals around a rotation central axis of the cylindrical portion 6 (specifically, the axis of the rotating shaft 5) or an axis of the casing 1 (referred to as “vacuum pump axis,” hereinafter).
On the inner peripheral side of the pump case 1A, on the other hand, a plurality of stator blades 8 are provided. These stator blades 8, too, are arranged radially at predetermined intervals around the vacuum pump axis, as with the rotor blades 7. A plurality of spacers S stacked along the direction of the vacuum pump axis are provided on the inner peripheral side of the pump case 1A, and the stator blades 8 are positioned and fixed at predetermined positions by these spacers S.
In the vacuum pump P1 shown in
In other words, the turbomolecular pump portion PT of the vacuum pump P1 in
Each of the rotor blades 7 is a blade-like cut product that is formed by cutting, integrally with an outer diameter treated portion of the cylindrical portion 6, and is inclined at an angle suitable for exhausting the gas molecules. Each of the stator blades 8 is also inclined at an angle suitable for exhausting the gas molecules.
Exhaust Operation by Turbomolecular Pump Portion PT
By starting the drive motor MO, in the exhaust stage PT1 at the top, the plurality of rotor blades 7 rotate at high speed integrally with the rotating shaft 5 and the cylindrical portion 6, and the inclined surfaces of the rotor blades 7 (specifically, the surfaces forward of the rotation direction and inclined downward (the direction from the inlet port 2 toward the outlet port 3, which is abbreviated as “downward,” hereinafter)) impart a momentum in a downward tangential direction to the gas molecules introduced from the inlet port 2. The gas molecules with such momentum are sent to the subsequent exhaust stage PT2 by the inclined surfaces of the stator blades 8 (specifically, the surfaces inclined downward in a direction opposite to the rotation direction of the rotor blades 7).
In the subsequent exhaust stage PT2 and the following exhaust stages as well, as in the uppermost exhaust stage PT1, the rotor blade 7 impart the momentum to the gas molecules and the stator blades 8 send the gas molecules. As a result, the gas molecules in the vicinity of the inlet port 2 are exhausted so as to move sequentially toward the downstream of the cylindrical portion 6.
Configuration of Thread Groove Pump Portion PS
The thread groove pump portion PS has a thread groove pump portion stator 9 (see
The thread groove pump portion stator 9 is a cylindrical stator member having an inner peripheral surface facing the outer peripheral surface of the cylindrical portion 6. The thread groove pump portion stator 9 is arranged so as to surround the part of the cylindrical portion 6 that is downstream of approximately the middle of the cylindrical portion 6.
The part of the cylindrical portion 6 that is downstream of approximately the middle of the cylindrical portion 6 is a part rotating as a rotary component of the thread groove pump portion PS, and is inserted/housed in the thread groove pump portion stator 9, with a predetermined gap therebetween.
A thread groove 91 (see
The thread groove flow path R for exhausting the gas is formed on the outer peripheral side of the cylindrical portion 6 by the thread groove pump portion stator 9 having the thread groove 91 described above. Although not shown, the thread groove flow path R described above may be provided by forming the thread groove 91 described above in the outer peripheral surface of the cylindrical portion 6.
In the thread groove pump portion PS, since the gas is transferred while being compressed by the thread groove 91 and the drag effect on the outer peripheral surface of the cylindrical portion 6, the depth of the thread groove 91 is set to be the deepest at the upstream entrance side of the thread groove flow path R (a flow path open end in the vicinity of the inlet port 2) and the shallowest at the downstream exit side of the same (a flow path open end in the vicinity of the outlet port 3).
The entrance of the thread groove flow path R (the upstream open end) is opened toward a gap between a stator blade 8E constituting the exhaust stage PTn at the bottom and the thread groove pump portion stator 9 (referred to as “last gap GE,” hereinafter), whereas the exit of the thread groove flow path R (the downstream open end) is communicated with the outlet port 3 through an in-pump outlet port side flow path S.
By providing a predetermined gap between a lower end portion of the cylindrical portion 6 or the thread groove pump portion stator 9 and the inner bottom portion of the pump base 1B (a gap circling a lower outer periphery of the stator column 4, in the vacuum pump P1 shown in
Exhaust Operation in Thread Groove Pump Portion PS
The gas molecules that have reached the last gap GE by being transferred by the exhaust operation in the plurality of exhaust stages PT1, PT2, PTn described above are transferred to the thread groove flow path R. The transferred gas molecules move toward the in-pump outlet port side flow path S while being compressed from a transitional flow to a viscous flow by the drag effect generated by the rotation of the cylindrical portion 6 downstream of approximately the middle thereof. The gas molecules that have reached the in-pump outlet port side flow path S flow into the outlet port 3 and are exhausted to the outside of the casing 1 through the auxiliary pump, not shown.
Explanation of Bouncing of Particle and Bounce Back Prevention Means J
Referring to
Accordingly, in order to prevent contamination of the vacuum chamber CH due to the backflow of the particle, in the vacuum pump P1 of
Configuration Example of Bounce back Prevention Means J (1)
In a specific configuration example (1) of the bounce back prevention means J, in the vacuum pump P1 of
In the vacuum pump P1 of
As shown in
Thus, in a case where the upper surface 9A of the thread groove pump portion stator 9 (stator component) is inclined as shown in
Incidentally, if the size of the particle is, for example, 10−3 times that of the height difference of the unevenness caused by the surface roughness of the upper surface 9A of the thread groove pump portion stator 9 (stator component), that is, if the particle is sufficiently small relative to the surface roughness of the upper surface 9A, the particle that has collided with the upper surface is reflected irregularly in a range wider than the above-mentioned scattering range. Thus, the inclination of the upper surface 9A of the thread groove pump portion stator 9 (stator component) is not enough to sufficiently control the reflection direction of the particle; it is difficult to effectively prevent the particle from bouncing from the thread groove pump portion PS to the turbomolecular pump portion PT.
Accordingly, in the vacuum pump P1 of
If the particle is sufficiently small relative to the surface roughness of the lower surface of the rotor blade 7 or stator blade 8 constituting the lowermost exhaust stage PTn (the surface of the thread groove pump portion PS that faces the upper surface 9A of the thread groove pump portion stator 9 (stator component)), the particle that has collided with the lower surface of the rotor blade 7 or stator blade 8 is also irregularly reflected in a range wider than the above-mentioned scattering range. Therefore, as a means for facilitating the transfer of the particle Pa toward the thread groove flow path R side by preventing the scattering of the particle caused by such irregular reflection, the lower surface of the rotor blade 7 or stator blade 8 constituting the lowermost exhaust stage PTn may be configured as the mirror surface.
For example, examples of the mirror finish include, but not limited to, a finishing process in which an arithmetic mean roughness Ra of the finishing mark in the JIS standard is 3.2 microns or less. More preferably, the finishing process achieves an arithmetic mean roughness Ra of 1.60 microns or less.
Configuration Example of Bounce Back Prevention Means J (2)
Since the basic configuration of the vacuum pump P2 of
In a configuration example (2) of the bounce back prevention means J, in the vacuum pump P2 of
Incidentally, as the number of particles Pa reaching the inlet port 2 increases, the number of particles near the upper surface of the thread groove pump portion stator 9 (stator component) increases accordingly. As a result, it is assumed that the particle is likely to scatter more easily near the upper surface of the thread groove pump portion stator 9 (stator component) due to the collision between particles, resulting in an increase in the number of particles that bounce back toward the turbomolecular pump portion PT.
In the vacuum pump P2 of
As a specific configuration example of the recess portion J1, in the vacuum pump P2 of
In addition, the recess portion J1 may include a smooth surface in at least a part of a surface of the recess portion J1. In a case where the recess portion J1 does not penetrate, that is, in a case where the recess portion J1 is composed of a side surface and a bottom surface, for example, when the side surface of the recess portion J1 is made smooth by mirror finishing or the like, and the roughness of the bottom surface of the recess portion J1 is made worse than the side surface, the effect of capturing a particle at the bottom surface and the effect of reducing kinetic energy can be improved.
In a case where the recess portion J1 is configured to penetrate as described above, if the side surface of the recess portion J1 is made smooth by mirror finishing or the like, the particle can be smoothly transferred to the particle trapping space J2.
As a specific configuration example of the particle trapping space J2, in the vacuum pump P2 of
In the case of the configuration provided with the particle trapping space J2, the particle that has entered the recess portion J1 further enters the particle trapping space J2 and is captured by the particle trapping space J2, making it difficult for the particle to collide with each other in the recess portion J1. In that respect, the effect of the recess portion J1, that is, the effect of capturing the particle and thereby reducing the number of particles bouncing toward the turbomolecular pump portion PT, can be maintained for a long period of time.
Moreover, as a specific configuration example of the recess portion J1, in the vacuum pump P2 of
Since many of the particles near the upper surface of the thread groove pump portion stator 9 (stator component) fall from the rotary gap G1 of the turbomolecular pump portion PT, the recess portion J1 is positioned near immediately below the rotary gap G1 as in the vacuum pump P2 of
The presence of the recess portion J1 near immediately below the rotary gap G1 ca reduce not only the area that contributes to the bouncing on the upper surface 9A of the thread groove pump portion stator (stator component), but also the area near immediately below the rotary gap G1 where many particles bounce back toward the inlet port 2 via the rotary gap G1 of the turbomolecular pump portion PT. Thus, the effect of further reducing the number of particles bouncing toward the turbomolecular pump portion PT can be expected.
The cross-sectional shape of the recess portion, the number of recess portions, the arrangement configuration thereof and the like described above can be changed appropriately as needed. For example, the cross-sectional shape of the recess portion J1 can be a square hole cross-sectional shape as shown in
In the vacuum pumps P1 and P2 of the embodiments described above, the bounce back prevention means J prevents the particle from bouncing from the thread groove pump portion PS toward the turbomolecular pump portion PT. Thus, the vacuum pumps P1 and P2 are suitable for preventing the backflow of the particle from the vacuum pumps P1 and P2 toward a vacuum chamber in terms of reducing the percentage of the bouncing particle flowing back toward the vacuum chamber upstream of the vacuum pumps P1 and P2.
The present invention is not limited to the foregoing embodiments, and many modifications can be made by those having ordinary knowledge in the art within the technical concept of the present invention.
For example, “Configuration Example of Bounce back Prevention Means (1)” and “Configuration Example of Bounce back Prevention Means (2)” described above may be appropriately combined and adopted as needed.
Although elements have been shown or described as separate embodiments above, portions of each embodiment may be combined with all or part of other embodiments described above.
Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are described as example forms of implementing the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-092143 | May 2019 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/019034 | 5/12/2020 | WO |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2020/230799 | 11/19/2020 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3832084 | Maurice | Aug 1974 | A |
| 4645413 | Reich | Feb 1987 | A |
| 5695316 | Schutz | Dec 1997 | A |
| 20150240829 | Ohtachi | Aug 2015 | A1 |
| 20180283386 | Kuno | Oct 2018 | A1 |
| 20180363662 | Kabasawa | Dec 2018 | A1 |
| Number | Date | Country |
|---|---|---|
| 3118651 | Jul 2022 | FR |
| H11329465 | Nov 1999 | JP |
| 2004076708 | Mar 2004 | JP |
| 2006013256 | Jan 2006 | JP |
| 2006144590 | Jun 2006 | JP |
| 4197819 | Dec 2008 | JP |
| 2016017454 | Feb 2016 | JP |
| 2018047036 | Mar 2018 | JP |
| 2018178733 | Nov 2018 | JP |
| 2009153874 | Dec 2009 | WO |
| 2011070856 | Jun 2011 | WO |
| Entry |
|---|
| Machine Translation of JP-4197819-B2 (Obtained from USPTO Search Copyright 2023 Clarivate Analytics) (Year: 2023). |
| Machine Translation of FR-3118651 (Obtained from USPTO Search Copyright 2023 Clarivate Analytics) (Year: 2023). |
| PCT International Search Report dated Jul. 28, 2020 for corresponding PCT application Serial No. PCT/JP2020/019034, 2 pages. |
| PCT International Written Opinion dated Jul. 28, 2020 for corresponding PCT application Serial No. PCT/JP2020/019034, 4 pages. |
| Jis B 0601, p. 1167 (1994). |
| Number | Date | Country | |
|---|---|---|---|
| 20220235776 A1 | Jul 2022 | US |
