JP2010112202A - Turbo-molecular pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain a temperature rise in a rotor of a turbo-molecular pump. <P>SOLUTION: This turbo-molecular pump 100 exhausts gas sucked in from an intake port 7A from an exhaust port 11A by rotating a rotor vane 3b. An electroless nickel plating layer is formed in a part facing the intake port 7A of a rotor body 3a, and a black nickel plating layer is formed on at least one of a surface of a plurality of rotor vanes 3b, a surface of a rotor cylindrical part 3c, an inner peripheral surface and an outer peripheral surface of the rotor body 3a. The black nickel plating layer promotes heat radiation to its peripheral member from the rotor since the heat radiation ratio is high. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a turbo molecular pump used for evacuation in a pressure range from a medium vacuum to an ultra-high vacuum such as a semiconductor manufacturing apparatus, a liquid crystal panel manufacturing apparatus, and an analysis apparatus.

  The turbo molecular pump is used as a means for exhausting a gas in a process chamber for performing dry etching, CVD or the like to form a predetermined high vacuum. When etching is performed by introducing a corrosive gas into the chamber, a heating means such as a heater is provided to prevent the reaction products from adhering to the chamber, APC valve, etc. connected to the intake side of the turbo molecular pump. Heating.

  Since the rotor rotates at a high speed, the rotor is made of an aluminum alloy having excellent specific strength, and stator blades, spacers, bases, and the like are often made of an aluminum alloy. In the case of a turbo molecular pump using a magnetic bearing, there is no heat transfer by conduction because the rotor floats without contact, and there is no heat transfer by convection because it is vacuum. The heat of the rotor is released only by heat transfer by radiation.

  There is a problem that the rotor becomes hot due to the heat from the upstream equipment such as the chamber and the APC valve, and if the rotor blade is rotated at a high speed while the temperature of the rotor blade is high, creep deformation is promoted. For this reason, it is necessary to suppress the transfer of heat to the rotor and to efficiently transfer the heat of the rotor to peripheral members such as a stator and a spacer. In order to promote heat exchange by heat radiation between the rotor blades and the stator blades, the step portions near the exhaust ports of the rotor blades and the stator blades are made of ceramic surfaces with high heat emissivity, and the other step portions are made of metal surfaces. A turbo molecular pump is known (for example, see Patent Document 1).

Japanese Patent No. 2527398

  In the turbo molecular pump of Patent Document 1, heat transfer is effectively performed from a rotor blade having a ceramic surface to a stator blade having a ceramic surface. However, heat transfer is not efficiently performed on a metal surface portion that is not a ceramic surface. In addition, there is a problem that corrosion by corrosive gas is likely to occur.

(1) A turbo molecular pump according to a first aspect projects radially from a bottomed cylindrical rotor body, and is arranged alternately with a plurality of rotor blades arranged in multiple stages in the rotation axis direction, and a plurality of rotor blades A turbine blade portion having a plurality of stator blades, a spacer for sandwiching and positioning each of the plurality of stator blades in the rotation axis direction, a casing having an intake port and housing the turbine blade portion, and an exhaust A base having a mouth, an electroless nickel plating layer is formed on a bottom surface facing the air inlet of the rotor body, and at least one of the surfaces of the plurality of rotor blades, the inner circumferential surface of the rotor body, and the outer circumferential surface of the rotor body. One is characterized in that a black nickel plating layer is formed.
(2) The invention according to claim 2 is the turbo molecular pump according to claim 1, wherein the rotor cylindrical portion provided on the exhaust port side of the plurality of rotor blades and the inner peripheral surface of the rotor cylindrical portion are opposed to each other. A screw pump section having a screw stator to be disposed, the base having a surface facing the inner peripheral surface of the rotor main body and the inner peripheral surface of the rotor cylindrical portion, the surface of the plurality of rotor blades, the inner peripheral surface of the rotor main body A black nickel plating layer is formed on at least one of the surface, the outer peripheral surface of the rotor body, and the surface of the rotor cylindrical portion.
(3) The invention according to claim 3 is the turbomolecular pump according to claim 2, wherein at least one surface of the plurality of stator blades, the screw stator, the spacer, and the base, the plurality of rotor blades, the rotor body, and the rotor cylinder A black nickel plating layer is formed on a surface facing any one of the portions.
(4) According to a fourth aspect of the present invention, in the turbo molecular pump according to the second or third aspect, a black nickel plating layer is formed on all of the surfaces of the plurality of rotor blades, the surface of the rotor body, and the surface of the rotor cylindrical portion. The protection member further includes a protection member disposed at the air inlet so as to face the rotor body, and the protection member is configured by a shielding plate in a region facing the bottom surface of the rotor body and a mesh in the other region. And

  According to the turbo molecular pump of the present invention, the electroless nickel plating layer is provided on the bottom surface of the rotor body facing the air inlet, and at least one of the surfaces of the rotor blades, the inner circumferential surface and the outer circumferential surface of the rotor body. Since the black nickel plating layer is provided, the heat transfer between the rotor and the upstream device can be reduced, the heat of the rotor can be efficiently transmitted to peripheral members such as a stator and a spacer, and the corrosion resistance can be improved.

Hereinafter, a turbo molecular pump according to an embodiment of the present invention will be described with reference to FIGS.
<First Embodiment>
FIG. 1 is a diagram schematically showing a configuration of a turbo molecular pump according to a first embodiment of the present invention. FIG. 1A is a top view of the turbo molecular pump, and FIG. 1B is a longitudinal sectional view of the turbo molecular pump.

  The turbo molecular pump 100 includes a turbine blade exhaust part 1 and a thread groove pump part 2. The rotor 3 includes a cylindrical rotor body 3a having a bottom on one side, a rotor blade (rotary blade) 3b formed in a plurality of stages so as to protrude in the radial direction from the rotor body 3a, and a downstream side of the plurality of rotor blades 3b. It has a rotor cylindrical portion 3c provided and a rotating shaft 3d. The stator blades (fixed blades) 4 formed in a plurality of stages are arranged with a gap of several millimeters alternately with the multistage rotor blades 3b by spacers 5. The turbine blade exhaust section 1 has a rotor blade 3 b and a stator blade 4 and is accommodated in a casing 6. An intake port flange 7 having an intake port 7A is provided above the casing 6. A net-like protective member 10 is attached to the intake flange 7 so as to face the bottom surface of the rotor body 3a, that is, the top surface 3A. Since the protective member 10 is mainly provided to prevent foreign matter from entering the turbo molecular pump 100 from the air inlet 7A, the size of the opening 10A of each mesh is very small.

  A screw stator 7 in which a screw groove is machined is disposed in the vicinity of the rotor cylindrical portion 3c. The thread groove processing may be performed on the rotor cylindrical portion 3 c instead of the screw stator 7. The thread groove pump portion 2 has a rotor cylindrical portion 3 c and a screw stator 8, and is disposed above the base 9. On the side of the base 9, an exhaust port flange 11 having an exhaust port 11A is provided. The base 9 is connected to the casing 6 in an airtight manner.

  The base 9 is further provided with a motor 12 for rotating the rotor 3 about the rotation shaft 3d, a pair of upper and lower radial magnetic bearings 13 and 14, and a thrust magnetic bearing 15. The radial magnetic bearing 13 has a radial electromagnet 13a and a radial sensor 13b, and the radial magnetic bearing 14 has a radial electromagnet 14a and a radial sensor 14b. The thrust magnetic bearing 15 includes a thrust electromagnet 15a and a thrust sensor 15b. The rotor 3 is supported by these radial magnetic bearings 13 and 14 and the thrust magnetic bearing 15 in a non-contact manner. In the vicinity of the radial magnetic bearings 13 and 14, protective bearings 16 and 17 are provided, respectively.

  In the turbo molecular pump 100 configured as described above, the inlet flange 7 is attached to a chamber side flange disposed in a process chamber (not shown) while maintaining airtightness by a bolt (not shown) penetrating the bolt hole 7a. ing.

  The turbo molecular pump 100 takes in gas from the upstream process chamber from the intake port 7A, exhausts it from the exhaust port 11A of the exhaust port flange 11 to the downstream side, and makes the inside of the process chamber a predetermined high vacuum. That is, when the rotor 3 rotates at a high speed of tens of thousands of rpm, the gas taken in from the intake port 7A passes through the gap between the rotor blade 3b and the stator blade 5 formed in multiple stages, and communicates with this gap. It is compressed while passing through the gaps in which the thread grooves are processed, and is discharged from the exhaust port 11A to the outside of the pump. Note that, unlike the above-described configuration, the turbo molecular pump includes an all-blade turbo molecular pump that does not have a thread groove pump portion on the downstream side.

  By the way, in a semiconductor manufacturing process, for example, in order to prevent a reaction product containing chlorine, fluorine sulfide or the like from condensing and depositing on the inner wall of the apparatus, the inside of the process chamber or the chamber side flange is heated to about 90 to 120 ° C. It is kept above the sublimation point of the reaction product. When this heat is transmitted to the rotor blade 3b by radiation, the creep deformation of the rotor blade 3b rotating at high speed is promoted, and there is a problem that the life of the rotor 3 is shortened. In the present embodiment, the heat of the rotor 3 is efficiently transmitted to peripheral members such as the stator 4 and the spacer 5 to lower the temperature of the rotor 3 and to reduce the heat transfer between the rotor 3 and the upstream device. There will be described in detail below with reference to FIGS.

  FIG. 2 is a partial longitudinal sectional view schematically showing the structure of the turbo molecular pump according to the first embodiment. FIG. 3 is a partial sectional view schematically showing the structure of the plating layer formed on the rotor of the turbo molecular pump according to the first embodiment. FIG. 3 (a) is an electroless nickel plating layer, and FIG. b) is a black nickel plating layer. 2 and 3, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  Referring to FIG. 2, an electroless nickel plating layer is provided on the upper surface 3A (indicated by rough hatching) of the rotor body 3a, that is, the surface facing the intake port of the rotor body 3a. Further, a black nickel plating layer is provided on the surface of the rotor blade 3b, the surface of the rotor cylindrical portion 3c, the inner peripheral surface 3B of the rotor main body 3a, and the outer peripheral surface 3C of the rotor main body 3a (indicated by fine hatching above). Yes. FIG. 2 shows that a black nickel plating layer is formed on all of the surface of the rotor blade 3b, the surface of the rotor cylindrical portion 3c, the inner peripheral surface 3B of the rotor main body 3a, and the outer peripheral surface 3C of the rotor main body 3a. However, it is sufficient that a black nickel plating layer is formed on at least one of the above surfaces.

  FIG. 3A shows the structure of the electroless nickel plating layer formed on the upper surface 3A of the rotor body 3a. The rotor 3 is made of an aluminum alloy, and a Ni-P (nickel-phosphorus) layer 101 is formed on the base material M of the aluminum alloy by an electroless plating method. The electroless nickel plating layer is one layer of the Ni-P layer 101, and its thermal emissivity is as low as 0.11. Here, the heat radiation rate is a coefficient representing the heat transfer characteristic by radiation, and heat becomes easier to transfer as the value increases. The black body has a heat radiation rate of one.

  FIG. 3B shows the structure of the black nickel plating layer. First, the Ni-P layer 101 is formed on the base material M of the aluminum alloy by the electroless plating method, and then the Ni-P layer 102 is formed by the electroless plating method using the Ni-P layer 101 as a base. The Ni—P layer 102 is a plating layer for blackening, and the black oxide film 103 is formed by etching the surface of the Ni—P layer 102. Therefore, the black nickel plating layer has a two-layer structure of the Ni-P layer 101 and the Ni-P layer 102 on which the black oxide film 103 is formed, and the thermal emissivity is as high as 0.65 to 0.73. Indicates.

  Further, from the viewpoint of corrosion resistance, nickel is superior in corrosion resistance compared to an aluminum alloy. Therefore, the corrosion resistance is improved by forming the electroless nickel plating layer or the black nickel plating layer on the aluminum alloy.

  As a processing step for plating the rotor 3, for example, the Ni-P layer 101 is first formed on the entire surface of the rotor 3, and then the upper surface 3A of the rotor body 3a and a predetermined surface are masked as necessary. The Ni—P layer 102 and the black oxide film 103 are formed on the other surfaces. Since the boundary between the electroless nickel plating layer and the black nickel plating layer is on the upper surface of the rotor 3, a general-purpose masking part using an O-ring as a seal can be used, and the masking operation can be easily performed.

The turbo molecular pump 100 according to the present embodiment has the following operational effects.
(1) Since the electroless nickel plating layer having a low heat radiation rate is provided on the upper surface 3A of the rotor body 3a, the heat radiated from the upstream device such as the process chamber is reflected and cut off and transmitted to the rotor 3. The amount of heat can be reduced, and the temperature rise of the rotor 3 can be suppressed.
The turbo molecular pump 100 is also used for exhausting an electron microscope or an exposure apparatus. In this case, since the process chamber and the valve are not heated, the rotor 3 that generates heat at a high speed is higher than the process chamber and the valve, and the heat of the rotor 3 flows into the upstream chamber by radiation. However, the radiant heat may adversely affect the electron beam or laser. However, in the turbo molecular pump 100 of the present embodiment, the amount of heat radiated to the upstream device such as the process chamber can be reduced by the electroless nickel plating layer having a low heat radiation rate, so there is no possibility of adversely affecting the upstream device. .

(2) At least one of the surface of the rotor blade 3b, the surface of the rotor cylindrical portion 3c, the inner peripheral surface 3B of the rotor main body 3a and the outer peripheral surface 3C of the rotor main body 3a is provided with a black nickel plating layer having a high heat radiation rate. Therefore, heat can be efficiently radiated from the rotor 3 to the peripheral members such as the stator blades 4 and the spacers 5, and the temperature rise of the rotor 3 can be suppressed. In particular, by keeping the temperature of the rotor blade 3b rotating at high speed low, creep deformation hardly occurs and the life of the rotor can be extended.

(3) Since the electroless nickel plating layer and the black nickel plating layer are provided as in (1) and (2) above, the corrosion resistance of the rotor 3 is improved in addition to the suppression of the temperature increase of the rotor 3. In particular, when an electroless nickel plating layer or a black nickel plating layer is provided on the entire surface of the rotor 3, the Ni-P layer 101 always covers the surface of the rotor 3, so that the corrosion resistance becomes higher.
Conventionally, electroless nickel plating has been applied to the upper surface of the rotor and the upstream surface (inlet side) of the rotor blades, and the other rotor blade surfaces have an electroless nickel plated lower layer and high thermal emissivity particle dispersion. There is known a turbo molecular pump having a two-layer plating (composite plating) composed of an upper layer of type electroless nickel plating (for example, Japanese Patent Laid-Open No. 2000-161286). However, the composite-plated particle-dispersed electroless nickel plating layer does not have a higher heat emissivity than the black nickel plating layer. Further, the boundary between the electroless nickel plating layer and the composite plating layer is a blade root rib portion or a cylindrical portion of the upstream first stage rotor blade and the second stage rotor blade, and is located deep from the tip surface of the rotor blade. Therefore, special masking is required. In the turbo molecular pump 100 of this embodiment, general masking is sufficient as described above.

<Second Embodiment>
FIG. 4 is a partial longitudinal sectional view schematically showing the structure of the turbo molecular pump according to the second embodiment of the present invention. 4, the same components as those in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof is omitted. The turbo molecular pump 200 according to the second embodiment is the same in configuration as the turbo molecular pump 100 according to the first embodiment, and differences will be described below.

  In the turbo molecular pump 200, in addition to forming a plating layer on the surface of the rotor 3, at least one surface of the stator blade 4, the spacer 5, the screw stator 8, and the base 9, the surface facing the rotor 3. A black nickel plating layer is formed on the surface.

  As shown in FIG. 4, in the turbo molecular pump 200, a black nickel plating layer is also provided on the stator blade 4, the spacer 5, the screw stator 8, and the surface 9 </ b> A of the base 9. The structure of the black nickel plating layer is the same as that shown in FIG. FIG. 4 shows that a black nickel plating layer is formed on all of the stator blade 4, the spacer 5, the screw stator 8, and the base 9, but at least one of these components is a black nickel plating layer. May be formed. Moreover, the black nickel plating layer may just be formed in the surface facing the rotor 3 of these components. For example, as shown in FIG. 4, a black nickel plating layer may be provided not on the entire surface of the base 9 but only on the surface 9 </ b> A facing the rotor 3.

  As described above, since the black nickel plating layer has a high thermal emissivity, in addition to forming the plating layer on the surface of the rotor 3, the stator blade 4, the spacer 5, the screw stator 8 and the base 9 are also plated with black nickel. By forming the layers, the rotor 3 having a high temperature can easily dissipate heat, and the members around the rotor such as the stator blades 4 and the spacers 5 having a low temperature can easily absorb heat. Therefore, in the turbo molecular pump 200, heat transfer from the rotor 3 to the peripheral members such as the stator blade 4 and the spacer 5 is performed more efficiently than the turbo molecular pump 100.

<Third Embodiment>
FIG. 5 is a diagram schematically showing a configuration of a turbo molecular pump according to the third embodiment of the present invention. FIG. 5A is a top view of the turbo molecular pump, and FIG. 5B is a longitudinal sectional view of the turbo molecular pump. In FIG. 5, the same components as those in FIG. The turbo molecular pump 300 according to the third embodiment has the same basic configuration as the turbo molecular pump 100 according to the first embodiment or the turbo molecular pump 200 according to the second embodiment. explain.

  The turbo molecular pump 300 is different from the turbo molecular pumps 100 and 200 in that the protective member 20 is different from the protective member 10 shown in FIG. The protection member 10 is configured by a mesh having a fine opening 10A over the entire area of the intake port 7A. On the other hand, the protective member 20 shown in FIG. 5 is a mesh 20a having an opening 20A in the peripheral portion, but a disk 20b as a shielding member is disposed in the central portion. That is, the protection member 20 has a structure in which the mesh 20a and the disk 20b are sequentially disposed inside the outer peripheral rib 20c. The diameter of the disc 20b is a dimension that does not reduce the exhaust action, and is, for example, a size corresponding to the upper surface 3A of the rotor body 3a on which the electroless nickel plating layer is provided.

  The protective member 20 functions to prevent foreign matter from entering the turbo molecular pump 300 from the air inlet 7A, and reflects or blocks heat radiated from the upstream device such as the process chamber to the rotor 3 or the like. There is a function to block heat radiated from the rotor 3 to the upstream device. For this reason, it is desirable that the surface of the protection member 20 be subjected to mirror finishing to increase the reflectance. The protective member 20 is made of stainless steel, and mechanical polishing or electrolytic polishing is used for mirror finishing. Further, a nickel film may be coated to finish the mirror surface. Although it is most desirable to perform a mirror finish on the entire surface of the protection member 20, only the surface of the disk 20b may be used for the convenience of processing. Thus, since the protection member 20 is provided with the disk 20b, the action of blocking the radiated heat is larger than that of the protection member 10 shown in FIG. Of course, also in this turbo molecular pump 300, the theory explained in the first and second embodiments can be applied, and the same effects as the turbo molecular pumps 100 and 200 can be obtained. In particular, in the turbo molecular pump 300, since the black nickel plating layer is formed on all of the surfaces of the plurality of rotor blades 3b, the rotor main body 3a, and the rotor cylindrical portion 3c, heat dissipation from the rotor 3 is achieved. Then, it is more effective than partially providing a black nickel plating layer.

Next, modified examples of the first to third embodiments will be described.
As shown in FIG. 3B, the black nickel plating layer has a two-layer structure of a Ni—P layer 101 and a Ni—P layer 102 having a black oxide film 103, but the upper Ni—P layer 102. The black oxide film 103 may be formed on the Ni-P layer 101. In this case, since it is a single layer of the Ni-P layer 101, one electroless plating treatment step can be omitted, and there is a manufacturing advantage.

  The present invention is not limited to the embodiments described above as long as the characteristics are not impaired. For example, when a black nickel plating layer is partially provided on the rotor 3, it is more effective to provide the rotor blade 3b, the rotor cylindrical portion 3c, and the rotor body 3a on a component having a high temperature. Usually, the rotor blade 3b is in a position where it is easy to receive radiant heat from upstream equipment such as a process chamber. Therefore, it is desirable to give priority to the rotor blade 3b in terms of heat dissipation. Similarly, when a black nickel plating layer is provided on the peripheral parts of the rotor 3, it is desirable to give priority to the stator blades 4 disposed close to the rotor blades 3b.

It is a figure which shows typically the structure of the turbo-molecular pump which concerns on the 1st Embodiment of this invention. FIG. 1A is a top view of the turbo molecular pump, and FIG. 1B is a longitudinal sectional view of the turbo molecular pump. It is a fragmentary longitudinal cross-sectional view which shows typically the structure of the turbo-molecular pump which concerns on 1st Embodiment. It is a fragmentary sectional view showing typically the structure of the plating layer formed in the rotor of the turbo-molecular pump concerning a 1st embodiment, Drawing 3 (a) shows an electroless nickel plating layer, and Drawing 3 (b) A black nickel plating layer is shown. It is a fragmentary longitudinal cross-sectional view which shows typically the structure of the turbo-molecular pump which concerns on 2nd Embodiment. It is a figure which shows typically the structure of the turbo-molecular pump which concerns on 3rd Embodiment. FIG. 5A is a top view of the turbo molecular pump, and FIG. 5B is a longitudinal sectional view of the turbo molecular pump.

Explanation of symbols

1: Turbine blade exhaust portion 2: Screw groove pump portion 3: Rotor 3a: Rotor body 3b: Rotor blade 3c: Rotor cylindrical portion 4: Stator blade 5: Spacer 6: Casing 7: Inlet flange 8: Screw stator 9: Base 10 , 20: protective member 11: exhaust port flange 20a: mesh 20b: disc 100, 200, 300: turbo molecular pump 101, 102: Ni-P layer 103: black oxide film

Claims (4)

A turbine blade portion having a plurality of rotor blades protruding in a radial direction from a bottomed cylindrical rotor body and arranged in multiple stages in the rotation axis direction, and a plurality of stator blades alternately arranged with the plurality of rotor blades When,
Spacers for sandwiching and positioning each of the plurality of stator blades in the rotation axis direction,
A casing having an air inlet and containing the turbine blade,
A base having an exhaust port,
An electroless nickel plating layer is formed on a bottom surface of the rotor body facing the air inlet, and at least one of a surface of the plurality of rotor blades, an inner circumferential surface of the rotor body, and an outer circumferential surface of the rotor body is black. A turbo molecular pump characterized in that a nickel plating layer is formed. The turbo-molecular pump according to claim 1,
A rotor cylindrical portion provided on the exhaust port side of the plurality of rotor blades, and a thread groove pump portion having a screw stator disposed to face and oppose the inner peripheral surface of the rotor cylindrical portion,
The base has a surface facing the inner peripheral surface of the rotor body and the inner peripheral surface of the rotor cylindrical portion,
A turbo molecular pump characterized in that a black nickel plating layer is formed on at least one of the surfaces of the plurality of rotor blades, the inner peripheral surface of the rotor body, the outer peripheral surface of the rotor body, and the surface of the rotor cylindrical portion. . The turbo-molecular pump according to claim 2,
A black nickel plating layer is formed on a surface of at least one of the plurality of stator blades, the screw stator, the spacer, and the base and facing any one of the plurality of rotor blades, the rotor body, and the rotor cylindrical portion. A turbo molecular pump characterized in that is formed. The turbo molecular pump according to claim 2 or 3,
A black nickel plating layer is formed on all of the surfaces of the plurality of rotor blades, the surface of the rotor body, and the surface of the rotor cylindrical portion,
A protective member disposed at the air inlet so as to face the rotor body;
The turbo molecular pump according to claim 1, wherein the protection member is configured such that a region facing the bottom surface of the rotor body is a shielding plate and the other region is a mesh.

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