JPH11247790A - Vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of exhaust velocity even when a protection net is provided for preventing entering of foreign materials. SOLUTION: A vacuum pump P performs exhausting from a suction port 2P of a casing 2 to an exhaust port 1P by the rotation of rotational bodies arranged in the casing 2, such as turbo mechanisms 5Y, 6. A protection net 15 is sandwiched between a spacer 71 and the casing 2 at the end of the suction port 2P on the side of the turbo mechanism, for preventing foreign materials from entering the turbo mechanism, from the side of the suction port 2P. It is thus unnecessary to project a flange inward from the suction port 2P so as to attaching a protection net. A maximum diameter of the suction port 2P is secured, while deterioration of exhaust velocity is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum pump used in a semiconductor manufacturing apparatus or the like, for example, a turbo molecular pump.

[0002]

2. Description of the Related Art In a high-speed rotary vacuum pump such as a turbo-molecular pump, when incorporated in a semiconductor manufacturing apparatus, foreign substances such as fragments of semiconductor wafers and screws may be sucked. When such foreign matter enters, the rotating body, that is, the rotating wing or the fixed wing is damaged, which is dangerous, and the exhaust function is reduced or destroyed. For this reason, a protection net for preventing (preventing) entry of foreign matter is provided at the suction port of the vacuum pump so that such foreign matter does not enter the rotating body in the pump device from the intake port.

FIG. 2 is a longitudinal sectional view showing the structure of a turbo molecular pump P provided with such a protection net N.

First, the configuration of the turbo molecular pump P will be described with reference to FIG. Reference numeral 1 denotes a base serving as a base of the turbo-molecular pump. A protrusion 1T for holding a rotary drive mechanism is formed at the upper center, and a base of a casing 2 is inserted around the base. The base 1 and the casing 2 are integrally formed and form a main body of the turbo molecular pump. A high-frequency motor 3 capable of high-speed rotation is inserted into a central hole of the protrusion 1T of the base 1.
The high-frequency motor 3 drives the rotary shaft 4 coupled to the rotor at high speed, and reference numerals 9 and 10 denote magnetic bearings for bearing the rotary shaft 4 in a non-contact manner. A rotor 5 is attached to the upper end of the rotating shaft 4. This rotor 5
, The rotating blades 5Y are radially extended at a constant interval toward the inner peripheral side of the casing 2. On the other hand, ring-shaped spacers 71, 72,.
N are arranged in a multi-layered manner, and fixed wings 6 whose bases are held between the spacers 71, 72,... 7N are held toward the outer peripheral side of the rotor 5, that is, inward. It is extended toward. Thus, this rotor 5Y
And the fixed wings 6 are alternately projected from the inside and the outside and overlap each other, and the surfaces thereof are inclined with respect to the rotor axis with their directions being opposite to each other, thereby constituting a so-called turbo mechanism. . Usually, the spacers 71, 7
2, 7N and the fixed wing 6 are used in combination of half-split type. Therefore, when the rotor 5 is rotated at a high speed by the high-frequency motor 3, an exhaust function is performed in which the gas (gas molecules) at the intake port 2P strikes the rotating blades 5Y and the fixed blades 6 and discharges them downward. The outer diameter of the rotor 5 increases as it goes down, so the amount of overlap between the rotor 5Y and the fixed wing 6 gets shorter as it goes down,
The capacity is reduced so that compression and exhaust can be performed. Further, a screw groove 5N is formed in the cylindrical portion below the rotor 5, and the gas molecules discharged by the turbo mechanism by the rotation of the screw groove 5N are more strongly discharged by viscous flow. To be discharged to

In FIG. 2, reference numeral 8 denotes a bearing holding frame for holding the magnetic bearing 9 and the ball bearing 12, which is implanted in the protrusion 1T, and 11 denotes a thrust magnetic bearing for supporting the rotor 5 and the like. . Further, a flange portion 2F for attaching a pipe 13 for connecting the vacuum pump P to a chamber to be evacuated, for example, a reaction chamber (not shown) in a semiconductor manufacturing apparatus, is provided at a portion of an intake port 2P which is an opening of the casing 2. Is provided, and a sealing member for air-tightly joining with the pipe 13, specifically, a gasket 14 is provided.
Is formed in the annular groove 2M.

With the above configuration, when the high-frequency motor 3 is driven to rotate at a high speed, the rotor 5 and the rotor blades 5Y
The turbo mechanism is activated by the rotation of, and the gas (gas molecules) at the intake port 2P is discharged downward and exhausted to the exhaust port 1P.
In this case, the rotor 5 is levitated by the magnetic bearings 9 and 10, so that high-speed rotation is ensured in a non-contact state, and high-speed exhaust is performed. The exhaust chamber evacuates the reaction chamber to a high vacuum region by this exhaust function. However, this vacuum pump P has an evacuation function in a high vacuum region, and is evacuated by an oil rotary pump in a low vacuum region. Therefore, the reaction chamber and the like are evacuated by both of these vacuum pumps.

On the other hand, a wafer on which a film is to be formed is mounted in a reaction chamber where exhaust is performed, but small pieces such as fragments thereof, screws, small screws, and washers may remain. These foreign substances may be sucked by the vacuum pump P via a pipe during the exhaust stroke of the reaction chamber.
In this case, if foreign matter such as these debris enters and comes into contact with the rotor 5Y or the fixed wing 6, the rotor 5Y or the fixed wing 6 may be damaged, which is dangerous and also reduces the exhaust function.
Or it will stop. When small dust or the like enters, it accumulates in the vacuum pump P, which may make the rotation of the rotating body impossible. If the intrusion of foreign matter lowers or disables the evacuation function of the vacuum pump P, it greatly impairs semiconductor manufacturing. Therefore, conventionally, as shown in FIG.
The protection net 15 is arranged at the upper end portion of. The protection net 15 has a mesh (wire net) stretched over, and allows ventilation, but prevents entry of foreign matter.

[0008]

The protection net 15
Is usually 0.3 mm to 1.0 m thick as shown in FIG.
A mesh-shaped wire mesh (mesh) 15N having a square hole of about 1 to 5 mm is used. Alternatively, a metal plate having a honeycomb-shaped hexagonal hole may be used. The protection net 15 is provided with an annular plate (ring) 15R around the protection net 15 in order to mount the protection net 15 on the intake port 2P.
5R is sandwiched between the pipe 13 and the flange 2F of the casing 2. As a mounting method other than the method shown in FIG. 2, a method in which a ring 16 is fitted to the flange portion 2F and the protection net 15 is fixed by the ring 16 (FIG. Hook 1
7 is provided, and the hook 17 is engaged with and fixed to the concave portion 2B formed in the flange portion 2F (FIG. 5). However, when the protection net 15 is attached to the intake port 2P as described above, a net supporting flange 2K for maintaining the attachment of the protection net is required. The net supporting flange 2K is installed so as to protrude inward at the intake port 2P. Therefore, the intake port 2P has an inner diameter D of the flange 2K which is smaller than the inner diameter L of the intake port of the casing 2.

The reason why the net supporting flange 2K must be protruded inward as described above is as follows.
That is, it is conceivable that only the step is provided without keeping the opening diameter of the casing 2 as it is without protruding inward, and the protection net 15 is supported on this step. In this case, it is necessary to form this step. Annular groove 2M for gasket 14
Are displaced more outwardly. However, when the annular groove 2M is installed outside, the mechanical strength of the flange portion 2F decreases. The mechanical strength can be maintained by increasing the diameter of the flange portion 2F and increasing the thickness of the cylindrical portion of the casing 2. However, in this case, it is necessary to increase the size and weight of the vacuum pump P. This is contrary to weight reduction. Therefore, at present, the net support flange 2K is provided so as to protrude inward, and the protection net 15 is attached to the flange portion 2K.

However, such a projection of the net supporting flange 2K causes the opening diameter of the intake port 2P to be the inner diameter D, and causes a reduction in the exhaust speed of the vacuum pump P from the relationship of L> D. I have. An object of the present invention is to provide a vacuum pump that solves such a problem.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a vacuum pump provided by the present invention does not hold a protective net at the inlet end of an intake port as in the prior art, but uses a casing. In this configuration, a protection net is disposed at the end of the intake port on the rotating body side. That is,
Specifically, it is a spacer for holding and holding the fixed wing between the casing and the casing.The protective net is sandwiched between the spacer and the casing closest to the intake port, and the protective net is arranged at a position other than the intake port. Things. Therefore, a flange or the like directed inward is not provided at the portion of the intake port, and the maximum diameter of the intake port can be used as an exhaust passage as it is, thereby ensuring a high exhaust speed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is as shown in FIG.

FIG. 1 is a view showing a longitudinal section of the vacuum pump of the present invention, similarly to FIG. 2, and the components denoted by the same reference numerals as those in FIG. 2 have the same functions as those in FIG.
A detailed description of the same configuration, functions and operations of parts as those in FIG. 2 will be omitted.

As shown in FIG. 1, the protective net 15 is provided between the casing 2 and the uppermost spacer 71 by the ring 15.
R is pinched and held.

This clamping is carried out prior to the assembling step of installing the turbo mechanism in the casing 2. However, before the uppermost spacer 71 is inserted into the step of the casing 2, the protection net 15 is placed inside. Installation can be realized simply by inserting. In this case, since the total height of the spacers 71, 72,... 7N in each step differs by the thickness of the protection net 15, the height of the uppermost spacer 71 is reduced or the step position on the casing 2 side is reduced. Needs to be displaced toward the intake port 2P. The embodiment of FIG. 1 is an example in which the height of the spacer 71 is slightly changed on the basis of the latter example, and the distance between the protection net 15 and the turbo mechanism (the rotor 5 or the rotary blade 5Y) is devised to be a fixed distance. It is. This is because when a large wafer fragment is sucked, the momentum of the fragment is large, and even if the mesh portion of the protection net 15 is slightly deformed to the turbo mechanism side, safety is considered so that the protection net 15 does not contact the turbo mechanism. Because he did.

If the shape of the protection net 15 is made of a strong rigid body, it can be prevented from being deviated even if the momentum of the fragments is large, and in this case, it can be arranged close to the turbo mechanism. The height of the uppermost spacer 71 can be reduced by the thickness of the protection net 15.

With such an arrangement of the protection net 15,
When foreign matter enters the intake port 2P, the foreign matter is caught by the protection net 15 and is prevented from entering the turbo mechanism.

Although the features of the present invention have been described in detail above, the present invention is not limited to the above and illustrated embodiments, but includes various modified embodiments utilizing the gist of the present invention.

First, the type of vacuum pump to which the present invention is applied is not limited to the example of the turbo-molecular pump as shown in the figure, but is evacuated by the rotation of a rotating body provided in a casing. The present invention can be applied to any vacuum pump as long as it exhibits a function. For example, it can be applied to a vacuum pump such as a molecular drag pump. That is, this is a molecular drag pump in which a protective net is arranged on the casing at the inner end of the rotating body at the intake port of the casing.

Further, even when the vacuum pump to be applied is a turbo molecular pump, the present invention is not limited to a pump in which the rotor is rotatably supported by a magnetic bearing system as shown in the illustrated example. Obviously, the present invention is applicable. In addition, regardless of the magnetic bearing method or the ball bearing method, the method of holding the fixed wing is not limited to the method using multi-stage spacers as shown in the illustrated example, and the method of holding with a single support frame. Can also. The illustrated example is a so-called hybrid type turbo-molecular pump combined with a rotor having a thread groove. However, the present invention can also be applied to a single-function turbo molecular pump having no rotor having a thread groove. As described above, the present invention can be applied to all turbo molecular pumps irrespective of differences in the type and partial mechanism of the turbo molecular pump. The shape, material, size, and the like of the protection net are not limited to the above-described contents, and various protection nets can be adopted as the material advances, and the present invention includes all of these modified embodiments.

[0021]

The vacuum pump provided by the present invention is as described in detail above, and it is possible to prevent a foreign substance from entering a rotating body by minimizing a decrease in the pumping speed. Damage to the rotating body, deterioration of the exhaust function, and destruction can be eliminated. That is, even if the exhaust speed is reduced due to the resistance of the protection net itself as long as the protection net is interposed in the exhaust path, the inner diameter of the exhaust port is not reduced because the protection net is installed as in the conventional case. ,
The reduction in the exhaust speed due to the reduction of the exhaust port is eliminated. Further, in the case of the illustrated embodiment, the heat of the rotating body is efficiently transmitted to the casing side, which has the effect of increasing the cooling. That is, the rotating body (turbo mechanism etc.) generates heat by the operation of the rotating body,
When the heat is radiated as radiant heat, the protection net is close to the rotating body and the protection net is sandwiched between the casings, so that the heat transmitted to the protection net is easily transmitted to the casing. Therefore, the heat of the rotating body is radiated through the casing, and cooling of the vacuum pump is enhanced as a whole. Further, in the case of the illustrated example, the installation method of the protection net is simple and easy, and an economical vacuum pump can be provided.

[Brief description of the drawings]

FIG. 1 is a view showing a vertical cross section of a vacuum pump of the present invention.

FIG. 2 is a view showing a longitudinal section of a conventional vacuum pump.

FIG. 3 is a diagram showing an appearance of a protection net.

FIG. 4 is a diagram showing a conventional protection net holding method.

FIG. 5 is a diagram showing a conventional method of holding a protection net.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Base 1T ... Projection part 1P ... Exhaust port 2 ... Casing 2P ... Inlet port 2M ... Annular groove 2K ... Protective net support flange 2F ... Flange 3 ... High frequency electric motor 4 ... Rotating shaft 5 Rotor 5Y Rotor blade 5N Screw groove 6 Fixed blade 71, 72, 7N Spacer 8 Bearing holding frame 9, 10 Magnetic bearing 11 Thrust magnetic bearing 12 Ball bearing 13 Piping 14 Gasket 15 Protection net 15R Ring plate of protection net 15N Wire mesh

Claims (2)

[Claims] 1. A vacuum pump for discharging a gas from an intake port of a casing to an exhaust port by performing a gas exhaust function by a rotation operation of a rotary body provided in the casing, wherein a rotary body side end of the intake port in the casing is provided. A vacuum pump, wherein a protection net for preventing foreign matter from entering from a suction body from entering a rotating body side is disposed at a portion thereof. 2. A turbo mechanism is provided with a rotor rotatably disposed in a casing, and a rotor mechanism protruding from an outer periphery of the rotor and fixed wings protruding from a spacer on an inner circumference of the casing. In a turbo mechanism type vacuum pump that exhausts gas from an intake port to an exhaust port by operation of a turbo mechanism, a protection net that prevents foreign matter from the intake port from entering the turbo mechanism side is closest to the intake port. A vacuum pump characterized by being disposed so as to be sandwiched between a spacer on the side and a casing.