JP2002155890A - Vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum pump having excellent heating efficiency and responsiveness when removing products adhered and deposited in the vacuum pump and implementing the increase in heating temperature. SOLUTION: The vacuum pump comprises: a rotor 2 rotatably installed in a pump case 1; a plurality of rotor blades 4 on an outer peripheral face on an upper side of the rotor 2; stator blades 5 arranged between the upper and lower rotor blades; a screw stator 7 arranged at a position opposite to an outer peripheral face on a lower side of the rotor 2. A sheathed 10 as a heating means is directly embedded or disposed to be fitted into the screw stator 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor manufacturing apparatus,
The present invention relates to a vacuum pump used for an electron microscope, a surface analyzer, a mass analyzer, a particle accelerator, a nuclear fusion experiment device, and the like.

[0002]

2. Description of the Related Art During a semiconductor manufacturing process, there are processes such as dry etching and CVD, and these processes are performed in a vacuum vessel called a process chamber. In this case, gas or the like generated in the process is exhausted to the outside of the vacuum vessel through a vacuum pump attached to the vacuum vessel. There is a possibility that a problem may occur in which the deposits are deposited and the normal operation of the vacuum pump is hindered.

For this reason, conventionally, dry etching or CV
In the case of a vacuum pump used in a process such as D, a well-known band heater is attached to the outer periphery of the pump case of the vacuum pump in order to prevent adhesion and deposition of products, and the vacuum pump is used with the band heater. Means have been taken such as heating from the outside or heating the partition inside the vacuum pump from outside the vacuum pump by heat conduction.

However, the portion where the product adheres or accumulates inside the vacuum pump is the portion where the exhaust gas contacts, so it is sufficient to heat only that portion. However, according to the conventional heating method, the above-mentioned heating method is sufficient. In order to heat the vacuum pump from the outside in this way, more energy is required to heat the part that should be heated, that is, the part where the exhaust gas contacts, heating efficiency and responsiveness and controllability of heating operation Is bad.

As described above, the conventional heating method uses a band heater. However, since the band heater uses a polymer material such as rubber, the heating method using this kind of band heater requires 100 ° C. The above-mentioned heating is difficult, and there is a problem that it cannot cope with a case where high-temperature heating of 100 ° C. or more is required to prevent adhesion and deposition of a product.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for heating and removing products adhering and accumulating inside a vacuum pump. An object of the present invention is to provide a vacuum pump that is excellent in heating efficiency, responsiveness and controllability of a heating operation, and can increase a heating temperature.

[0007]

To achieve the above object, the present invention provides a rotor rotatably installed in a pump case, a plurality of rotor blades provided on an outer peripheral surface on an upper side of the rotor, and In a vacuum pump including a stator blade disposed between the upper and lower rotor blades and a screw stator disposed at a position facing the outer peripheral surface on the lower side of the rotor, a sheath heater is provided on the screw stator. It is a feature.

The screw stator has a structure in which the upper side contacts the lowermost stator blade and the lower side contacts the gas exhaust port, and the sheathed heaters are densely arranged on the upper and lower sides of the screw stator. It can be.

In the present invention, the term "screw stator" includes those having a thread groove and those having no thread groove. In the case of a thread stator structure having a thread groove, the outer periphery of the rotor facing the screw stator is provided. Although there are some with and without a screw groove, in the case of a screw stator structure without a screw groove, a screw groove is formed on the outer peripheral surface of the rotor facing the screw stator.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a vacuum pump according to the present invention will be described in detail with reference to FIGS.

The vacuum pump of this embodiment shown in FIG.
A cylindrical rotor 2 is rotatably installed in a cylindrical pump case 1, and the rotor 2 is arranged so that its upper end faces the gas inlet 3 on the upper part of the pump case 1.

In the case of the present vacuum pump, the upper half of the rotor 2 as described above functions as a turbo molecular pump, and the lower half of the rotor 2 functions as a thread groove pump.

Here, the structure of the upper half side of the rotor 2 functioning as a turbo molecular pump will be described first. A plurality of machined blade-like rotor blades 4 and stator blades 5 are provided on the outer periphery on the upper side of the rotor 2, and the rotor blades 4 and the stator blades 5 alternate along the rotation center axis of the rotor 2. Are located in As described above, the upper outer periphery of the rotor 2 has a structure in which the stator blades 5 are arranged between the upper and lower rotor blades 4 and 4 or the rotor blades 4 are arranged between the upper and lower stator blades 5 and 5. Has become.

The rotor blades 4 are integrally provided on the upper outer peripheral surface of the rotor 2 by integral processing with the rotor 2 and can rotate integrally with the rotor 2.
Is mounted and fixed to the inner surface of the pump case 1 via a spacer 6.

Next, the configuration of the lower half of the rotor 2 functioning as a thread groove pump will be described. A screw stator 7 is disposed at a position facing the lower outer periphery of the rotor 2. The screw stator 7 has a cylindrical shape surrounding the lower outer periphery of the rotor 2, and is fixed to the inner wall side of the pump case 1. I have.

A thread groove 8 is formed in the screw stator 7, and the thread groove 8 is provided on the side of the screw stator 7 facing the rotor.

The upper portion of the screw stator 7 is configured to be in contact with the spacer 6 and the stator blade 5, and the lower portion of the screw stator 7 is configured to be in contact with the gas exhaust port 9 below the pump case 1. Have been.

The screw stator 7 has the largest heat capacity among the internal structural members of the present vacuum pump, and the screw stator 7 having such a large heat capacity incorporates a well-known sheath heater 10 as heating means.

Regarding the structure system in which the sheathed heater 10 is built in the screw stator 7, for example,
And a structure in which a groove is formed in the screw stator 7 and the sheath heater 10 is fitted and installed in this groove.

In the case of the above-mentioned buried structure, for example, when the screw stator 7 is manufactured by die casting, the sheath heater 10 may be set in the die casting mold.

Sheath heater 10 in screw stator 7
May be uniformly uniform from the upper part to the lower part of the screw stator 7, but in the present embodiment, the sheathed heaters 10 are arranged densely on the upper and lower sides of the screw stator 7. The reason why the arrangement density of the sheathed heaters 10 is changed in this way is that the spacers 6, the stator blades 5, and the gas exhaust ports 9 that are in contact with the screw stator 7 are warmed by heat conduction, and the entire screw stator 7 is uniformly heated. In order to

That is, comparing the heat radiation between the upper and lower parts of the screw stator 7 and the central part, the heat radiation is better in the upper and lower parts of the screw stator 7, so that the temperature of the upper and lower parts of the screw stator 7 tends to be particularly low. . Therefore, in the present embodiment, the sheathed heaters 10 are densely arranged in the upper and lower portions of the screw stator 7, so that the entire screw stator 7 is heated to a uniform temperature.

Next, the configuration inside the rotor 2 will be described. Inside the rotor 2, a rotor shaft 11 is integrally mounted on the rotation center axis. Although various types of bearing means for the rotor shaft 11 are conceivable, the present embodiment employs a configuration in which the ball bearing 12 supports the rotor shaft 11 in bearings.

The rotor shaft 11 is connected to the drive motor 1.
3 is driven to rotate. Regarding the structure of this type of drive motor 13, a motor stator 13 a is attached to a stator column 14 installed inside the rotor 2, and the motor rotor 13 is attached to the outer peripheral surface of the rotor shaft 11 facing the motor stator 13 a. 13b is provided.

The gas inlet 3 on the upper side of the pump case 1 as described above is connected to a vacuum vessel side where a high vacuum is provided, such as a process chamber of a semiconductor manufacturing apparatus, and the gas exhaust port 3 on the lower side of the pump case 1. 9 is set so as to communicate with the low pressure side.

Therefore, in the present vacuum pump, the turbo molecular pump mechanism A for performing the exhaust operation by the interaction between the rotating rotor blades 4 and the fixed stator blades 5 is located on the side where high vacuum is applied, and The screw groove pump mechanism B which performs the exhaust operation by the interaction between the rotor 2 and the screw groove 8 is located on the low pressure side.

In the turbo-molecular pump mechanism A, gas molecules are exhausted by the interaction between the rotating rotor blades 4 and the fixed stator blades 5, but the high vacuum (degree of vacuum: 10 ⁻⁶ Pa) can be obtained.

Next, an example of use and operation of the vacuum pump configured as described above will be described with reference to FIG. The arrows in the figure indicate the flow direction of the exhaust gas in the vacuum pump.

The vacuum pump shown in FIG. 1 can be used, for example, as a means for evacuating the inside of the process chamber of a semiconductor manufacturing apparatus. It shall be connected to the process chamber side.

In the vacuum pump connected as described above, the auxiliary pump (not shown) connected to the gas exhaust port 9 is operated to set the inside of the process chamber to the order of 10 ^-1 Torr, and then the operation start switch is turned on. Then, the drive motor 13 operates, and the rotor 2 is integrated with the rotor shaft 11.
And the rotor blade 4 rotates.

In this case, the gas molecules are evacuated in the turbo-segmented pump mechanism section A in such a manner that the uppermost rotor blade 4 rotating at a high speed applies a downward momentum to the gas molecule groups incident from the gas inlet 3. The operation is such that the gas molecules having the downward momentum are guided by the stator blade 5 and are sent to the next lower rotor blade 4 side. By repeating the application of the momentum, the gas suction is performed. Gas molecules move from the port 3 to the screw groove 8 side and are exhausted.

Gas molecules reaching the thread groove 8 side are
Due to the interaction between the rotating rotor 2 and the thread groove 8, the transition flow is compressed into a viscous flow and transferred to the gas exhaust port 9 side.
The gas is exhausted from the gas exhaust port 9 to the outside of the pump by an auxiliary pump (not shown).

By the way, in the present vacuum pump, depending on the type of the exhaust gas, there is a possibility that a product may adhere or accumulate inside the vacuum pump, thereby hindering normal operation of the vacuum pump. If there is a possibility that this occurs, the sheathed heater 10 is caused to generate heat by turning on a heater switch (not shown).

When the heater switch is turned on, the screw stator 7 is directly heated by the sheathed heater 10, and
The spacer 6 in contact with the upper side of the screw stator 7
, The stator blade 5 and the gas exhaust port 9 which is in contact with the lower side of the screw stator 7 are both heated by heat conduction, and the adhesion and deposition of products on the screw stator 7, the stator blade 5 and the gas exhaust port 9 Is prevented beforehand.

FIG. 2 is a vapor pressure curve diagram of four kinds of exhaust gases (silicon tetrafluoride, tungsten hexafluoride, silicon tetrachloride, and aluminum chloride). Is in a solid or liquid state. According to the vapor pressure curve shown in FIG. 5, it can be seen that all four types of exhaust gas change from gas to solid or liquid when the pressure increases.

In the case of the present vacuum pump, the exhaust gas as described above is unlikely to be a solid product because of the low pressure near the high vacuum side in the vicinity of the gas intake port 3. And the like, the pressure gradually increases in the direction of the screw stator 7, so that the stator blades 5 and the rotor blades 4 adjacent to the screw stator 7, the screw groove 8 of the screw stator 7, the outer peripheral surface of the rotor 2 opposed thereto, and In the vicinity of the gas exhaust port 9, the exhaust gas tends to be a solid product. Accordingly, in the vacuum pump according to the present embodiment, as described above, the screw stator 7 is used as a heating means because of the internal environment of the vacuum pump and the fact that the screw stator 7 is a pump structural material having the largest heat capacity inside the vacuum pump. A heater 10 was provided. For this reason, according to the vacuum pump of the present embodiment, the screw stator 7 on which the product is liable to adhere or accumulate is directly heated by the sheath heater 10,
The energy required for heating can be reduced, and the responsiveness and controllability of the heating operation can be improved.

The temperature sensor 15 for controlling the heater is usually attached to a part of the screw spacer, but forms the spacer 6, the stator blade 5, the gas exhaust port 9, the pump case 1, or the bottom of the pump case 1. Base 1
6, the temperature sensor 15 for controlling the heater.
May be attached.

Further, in the vacuum pump of the present embodiment, since the sheath heater 10 is directly embedded or fitted into the screw stator 7, the power input density per unit length can be increased, and The responsiveness and controllability of the operation can be further improved, and the need for high-temperature heating of 100 ° C. or higher, which cannot be realized by a conventional band heater, can be met, and the heating temperature can be increased.

Further, according to the vacuum pump of the present embodiment, since the spacer 6, the stator blade 5 and the gas exhaust port 9 are in direct contact with the screw stator 7, the spacer 6 and the stator blade 5 near the screw stator 7 are used. , And the gas exhaust port 9 are also heated by heat conduction, so that a rapid temperature change of the gas does not occur, and the adhesion and deposition of the product on the gas exhaust port 9 and the like can be effectively prevented.

The screw groove 8 may be provided not on the screw stator 7 side but on the rotor 2 side. In this case, the screw groove 8 is formed on the outer peripheral surface of the rotor 2 facing the screw stator 7.

As the bearing means of the rotor shaft 11, in addition to the above-described ball bearing 12, for example, a non-contact type bearing such as a magnetic bearing can be applied.

[0042]

As described above, in the vacuum pump according to the present invention, since the heating means is provided on the screw stator, the screw stator to which the product easily adheres and deposits can be directly heated by the heating means. Energy required for heating, and the responsiveness and controllability of the heating operation can be improved.

According to the present invention, a sheath heater is used as the heating means, and the sheath heater is directly embedded or fitted into the screw stator, so that the power input density per unit length can be increased. The responsiveness and controllability of the heating operation can be further improved,
It can meet the needs of high-temperature heating of 100 ° C. or higher, and can increase the heating temperature.

[Brief description of the drawings]

FIG. 1 is a pump cross-sectional view showing one embodiment of a vacuum pump according to the present invention.

FIG. 2 is a vapor pressure curve diagram of exhaust gas.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pump case 2 Rotor 3 Gas intake port 4 Rotor blade 5 Stator blade 6 Spacer 7 Screw stator 8 Screw groove 9 Gas exhaust port 10 Sheath heater (heating means) 11 Rotor shaft 12 Ball bearing 13 Drive motor 13a Motor stator 13b Motor rotor 14 Stator column 15 Temperature sensor 16 Base A Turbo molecular pump mechanism B Thread groove pump mechanism

Claims (2)

[Claims] A rotor rotatably installed in a pump case; a plurality of rotor blades provided on an outer peripheral surface on an upper side of the rotor; a stator blade disposed between upper and lower rotor blades; What is claimed is: 1. A vacuum pump comprising: a screw stator disposed at a position facing an outer peripheral surface on a lower side of a rotor; 2. The screw stator has a structure in which an upper side thereof contacts the lowermost stator blade and a lower side thereof contacts a gas exhaust port, and the sheathed heater is densely arranged on upper and lower sides of the screw stator. The vacuum pump according to claim 1, wherein the vacuum pump is arranged.