JP3252792B2 - Turbo vacuum pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbo type vacuum evacuation apparatus mainly used in a semiconductor manufacturing apparatus for performing an aluminum etching process or the like.

[0002]

2. Description of the Related Art When a turbo-type dry pump or the like is used as a vacuum exhaust device of a semiconductor manufacturing apparatus for performing an aluminum etching process or the like, the vacuum exhaust device sucks, compresses and exhausts an etching gas (BCl3, CCL4, etc.). become. Thus, the etching gas causes a chemical reaction to form a solid reaction product, and the reaction product is compressed on the etching gas flow path inside the pump, particularly when the pressure is increased, and the reaction product is compressed. It has been pointed out that there is a problem that it adheres near the exhaust port. As a result, not only does the effective cross-sectional area of the exhaust port decrease, so that the vacuum evacuation performance of the pump deteriorates. And hindered the rotation of the rotor, causing a failure.

As a countermeasure against this, a pump is provided to expand the space between the rotor and the stator near the exhaust port, or to prevent the adhesion of such reaction products and to remove the attached reaction products by sublimation. A heater or the like for keeping the temperature near the exhaust port of the pump at a high temperature (for example, around 180 ° C.) was provided, and a high-temperature inert gas was supplied near the exhaust port of the pump for the purpose of diluting the reaction product. .

[0004]

However, merely expanding the space between the rotor and the stator near the exhaust port as described above does not provide a drastic measure. Regular maintenance is required. In addition, the method of preventing the adhesion of reaction products by providing a heater leads to an increase in size and cost of the device due to the attachment of the heater, an increase in the number of parts, and the like. Even by introducing a hotter inert gas near the exhaust port,
In addition to the need for a heater that raises the temperature of the inert gas, a new flow path for the inert gas must be provided in the device, and as described above, the device becomes larger, more expensive, and the number of parts increases. Invite.

In order to solve such problems at once, the present invention focuses on the point that an inert gas for cooling a bearing is supplied to a gas bearing in a turbo-type vacuum evacuation apparatus using a gas bearing. Provided is a turbo-type vacuum exhaust device which can heat the vicinity of an exhaust port by using the inert gas which has been heated to a high temperature after finishing a cooling operation and which can prevent the adhesion of reaction products by a simple mechanism. The purpose is to:

[0006]

That is, a turbo-type vacuum evacuation apparatus according to the present invention comprises a housing, a rotor housed inside the housing and having rotor blades provided on the outer peripheral surface, and one end of the rotor integrated with the rotor. A fixedly mounted support shaft, a gas bearing interposed between the support shaft and the housing and rotatably supporting the support shaft at the other end, and a motor for rotating the support shaft A gas such as an etching gas is sucked from a suction port by the rotation of the rotor, and the gas is moved along the rotor to exhaust the gas from the exhaust port. While introducing the gas, the introduced inert gas is passed through a motor and a gas bearing to raise the temperature, and then the heated inert gas is passed at least along the inner peripheral surface of the rotor. This was heated Te, characterized in that a inert gas flow path configured to discharge outside the housing.

With this structure, the rotor can be heated by using the inert gas which has passed through the motor and the gas bearings, has completed the cooling operation, and has become high in temperature. Therefore, the etching gas and the like flowing along the rotor can be heated without providing a heating mechanism such as a heater, and the adhesion of the reaction product to the flow path of the etching gas and the like can be prevented with a simple mechanism.

In order to easily construct the inert gas flow path and to improve the rotation stability of the rotor, the rotor is cylindrical and the support shaft is attached at one end to the inside of the rotor. Is preferred. As a specific embodiment that can effectively prevent the adhesion of the reaction product , an inert gas is introduced into the housing from outside the housing.
Introduce the inert gas
Through the gas bearing and / or gas bearing
After that, the high temperature inert gas flows out of the exhaust port
Then, a configuration in which the vicinity of the exhaust port is heated can be given. In this case, in order to particularly effectively dilute the reaction product, it is preferable that a through-hole penetrating from the inner peripheral surface to the outer peripheral surface of the rotor is provided all around the rotor.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. Turbo vacuum evacuation apparatus 100 according to the present embodiment
As shown in FIG. 1, a rotor 1 having a casing 5 and a circumferential pump 11 as a plurality of rotating blades provided on the outer periphery thereof.
A support shaft 2 screwed to the rotor 1;
That are provided with dynamic pressure gas bearings 31 and 32 as non-contact type gas bearings for rotatably supporting the rotor, and an electric motor 4 for rotating the support shaft 2, with the rotor 1 standing up and used. It is.

The rotor 1 is cylindrical. Specifically, the lower half 1a is provided with a plurality of disk-shaped circumferential pumps 11 on the outer periphery, and the upper half 1b is a cylinder having no irregularities on the outer peripheral surface. In the middle, a disc-shaped support member 12 for partitioning like a bamboo node is integrally formed, and an insertion hole 13 is formed so that the support shaft 2 can be attached to the support member 12. ing. Circumferential pump 11
As shown in FIG. 2, by providing a plurality of notches 11b intermittently and radially on the upper surface of the outer peripheral portion 11a, a plurality of notches 11b is provided between the notch 11b and the adjacent notch 11b. Is formed.

The casing 5 has a rotor holding chamber 51 for accommodating the rotor 1 and a bearing holding chamber 52 provided continuously below the rotor holding chamber 51 and for accommodating the support shaft 2. The rotor holding chamber 51 includes a suction port 53 opening above the rotor 1 and an exhaust port 54 opening to the side of the rotor 1. Further, a thread groove 55a is formed in a portion corresponding to the upper half portion 1b of the rotor 1, and a portion corresponding to the lower half portion 1a of the rotor 1 is formed in the stator portion 55 which is an inner peripheral portion thereof. A fixed groove 55b into which the outer peripheral portion 11a of the pump 11 can be loosely fitted is provided around the periphery. In the fixing groove 55b, as shown in FIG. 4, an inverted U-shaped groove 55c is formed on the downward surface. This groove 55c is
It does not go around as shown in FIG. 3 and is not provided in a part. Thus, a through hole 55e penetrating downward from the end 55d of the groove 55c in the rotation direction of the rotor 1 to the next fixed groove 55c is provided.

In the bearing holding chamber 52, a motor disposition portion 55 for disposing a motor 4 to be described later is provided at a lower end portion thereof, and a thrust bearing 32 described later is disposed above the motor disposition portion 55. And the thrust bearing disposition portion 56 of FIG. Further, an external connection path 6 extends from the lower end and communicates with an external port 7 opened on the outer surface of the casing 5.

The support shaft 2 has a threaded portion 21 integrally protruded from an upper portion 2a at one end thereof. The male threaded portion 21 is passed through an insertion hole 13 penetrated through the support member 12 to protrude. The nut 22 is attached to the rotor 1 by screwing it to the portion. On the other hand, a disk body 23 is integrally fixed near the lower end 2b on the other end side. Dynamic pressure gas bearing 31,
Reference numeral 32 denotes a journal bearing 31 that supports the support shaft 2 against a load acting in the journal direction, and a thrust bearing 3 that supports the support shaft 2 against a load acting in the thrust direction.
And 2. The journal bearings 31 are disposed at two places from above and below the support shaft 2. For example, the journal bearings 31 are formed by rolling a rectangular thin plate, and one end thereof is supported on the inner wall surface of the bearing holding chamber 52. Support shaft 2
And a journal support plate 33 disposed around the periphery of the journal support plate 33.
3 and a plurality of leaf spring members 34 which are elastically urged inward to press against the support shaft 2. Thrust bearing 3
Reference numeral 2 denotes, for example, ring-shaped thrust support plates 36 provided above and below the disk body 23, and elastically biases the thrust support plates 36 provided above and below the thrust support plates 36 to push the disk body 21. And a ring-shaped leaf spring member 37 to be brought into contact therewith. When the support shaft 2 is stationary or at a certain rotation speed or less, the journal support plate 33 and the thrust support plate 36 are brought into close or close contact with the support shaft 2 by the elastic urging force of the leaf spring members 34 and 37 to support the journal. While supporting the shaft 2, a dynamic pressure is generated around the support shaft 2 and on the upper and lower surfaces of the disk body 21 by utilizing the gas caught by the rotation of the support shaft 2 when the rotation speed becomes equal to or higher than a certain number of rotations. Journal support plate 33 and thrust support plate 36
Is receded to form a gas film, and the function of supporting the support shaft 2 in a non-contact manner through the gas film is provided. The inert gas such as nitrogen supplied to the dynamic pressure gas bearings 31 and 32 is supplied from the external port 7 via the external connection path 6.

The motor 4 includes a rotator 41 having an outer diameter substantially equal to that of the support shaft 2 and built therein so as not to protrude from the outer peripheral surface 2 c of the support shaft 2, and a motor mounting portion 55 around the rotator 41. For example, a DC brushless type having a stator 42 disposed on the support shaft 2
Is driven. In the present embodiment, an inverter (not shown) is used as a drive source of the motor 4, and the inverter is configured to rotate the motor 4 at an arbitrary rotation speed.

By rotating the rotor 1 by the motor 4, the turbo-type vacuum exhaust device 100 configured as described above sucks, for example, an etching gas or the like in a chamber of a semiconductor manufacturing device (not shown) from a suction port 53.
It is moved downward along the screw groove 55a. However, this operation is performed in the molecular flow region, and the screw type pump portion provided with the screw groove 55a functions as a centrifugal compression pump. Then, the etching gas and the like compressed by the screw-type pump stage and led to the lowermost stage of the screw groove 55a are then transferred to the fixed groove 55b by the rotation of the circumferential pump 11,
Specifically, an inverted U-shaped groove 55 provided in the fixing groove 55b
Move along c. The etching gas or the like that moves along the rotation direction of the circumferential pump 11 and is compressed
c, a through hole 55e provided at the end 55d on the rotation direction side
, Flows into the next (lower) fixed groove 55b, and is moved to the lower fixed groove 55b one after another while being compressed in each stage by the same operation again. Then, the air is discharged from the final fixed groove 55 b to the outside of the housing 5 through the exhaust port 54. This operation is performed in the viscous flow region, and the portion provided with the circumferential pump 11 functions as a circumferential flow compression pump.

In this embodiment, however, an inert gas is introduced into the housing 5 from the outside of the housing 5, and the introduced inert gas is brought into contact with the motor 4, and is applied to the dynamic pressure gas bearings 31 and 32. An inert gas flow path 8 configured to contact the rotor 1 after the supply and discharge the gas to the outside of the housing 5 is provided. Specifically, the inert gas flow path 8 is formed between the above-described external port 7, the external connection path 6, the bearing holding chamber 52, and the inner peripheral surface 1 c on the lower side of the rotor 1 and the rotor holding chamber 51. It comprises a gap 81, a gap 82 formed between the lower end 1 d of the rotor 1 and the rotor holding chamber 51 and communicating with the exhaust port 54, and an exhaust port 54. Then, the inert gas introduced from the external port 7 is circulated in the order described above. At this time, the inert gas flowing into the bearing holding chamber 52 through the external port 7 and the external connection path 6 cools the motor 4 and the dynamic pressure gas bearings 31 and 32 in the bearing holding chamber 52, and the inert gas itself has a high temperature. And the lower inner peripheral surface 1 of the rotor 1
and flows into a gap 81 formed between the rotor c and the rotor holding chamber 51 to contact the inner peripheral surface 1c of the rotor 1 to heat the rotor 1. Then, the air is discharged from the gap 82 formed between the lower end 1 d of the rotor 1 and the rotor holding chamber 51 to the exhaust port 54. In this embodiment, as shown in FIGS. 2 and 4, the rotor 1 is located near the lower end 1 d of the rotor 1.
One end 91 is opened in the inner peripheral surface 1c of the rotor 1 and the through hole 9 that penetrates the circumferential pump 11 of the last stage and opens the other end 92 in the cutout groove 11b of the circumferential pump 11 is formed around the entire circumference of the rotor 1. So that the inert gas flowing along the gap 81 can flow into the exhaust port 54 even through the through hole 9.

Therefore, according to the present embodiment configured as described above, the rotor 1 can be heated by using the above-mentioned inert gas which has reached a high temperature after the cooling operation. Therefore, the etching gas or the like flowing along the outer peripheral surface 1c of the rotor 1 can be heated without providing a heating mechanism such as a heater, and the adhesion of reaction products can be prevented by a simple mechanism. Further, since the rotor 1 is cylindrical, the inert gas can be supplied to the rotor 1 without providing an inert gas circulation path or the like in the rotor 1.
The inert gas can be efficiently and easily brought into contact with the rotor 1 by guiding the inert gas to the inner peripheral surface 1c. That is, the inert gas flow path 8 can be easily configured. In addition, since the support shaft 2 has one end attached to the rotor 1, the center of gravity of the rotor 1 and the positions of the dynamic pressure gas bearings 31 and 32 that support the support shaft 2 are close to each other.
The rotation stability of the rotor 1 can be reasonably improved.

Further, since the high temperature inert gas is guided to the circumferential pump 11 at the final stage and is caused to flow out from the exhaust port 54, it is particularly necessary to heat the vicinity of the exhaust port 54 where reaction products are likely to adhere. Not only can exhaust
Thus, a compressed gas such as an etching gas can be diluted with an inert gas. Therefore, the adhesion of the reaction product can be prevented very effectively. Furthermore, there is an effect on simplification of the structure that a separate outlet for discharging the inert gas does not have to be provided.

Further, since the high-temperature inert gas is in contact with the entire circumference of the final stage circumferential pump 11 and the corresponding fixed groove 55c by the through hole 9, the dilution effect by the inert gas is increased. Not only the exhaust port 54 but also the final stage of the circumferential pump 11 and the fixed groove 5.
Adhesion of the reaction product to 5c can also be effectively prevented.

The unique effect of this embodiment is that the rotor 41 of the motor 4 is embedded in the support shaft 2 so that the motor rotor 41 does not protrude from the outer peripheral surface 2c of the support shaft 2, so that the size can be reduced. Is mentioned. In addition, the inner diameter of the thrust support plate 36 and the inner diameter of the leaf spring member 37 can be made substantially equal to the outer diameter of the support shaft 2, so that their sizes can be made as small as possible. As a result, the thrust support plate 36 and the leaf spring material 3 constituting the dynamic pressure gas bearing 32
7, the sliding speed with the disk body 23 can be reduced as much as possible.
It is possible to reduce wear and friction loss and contribute to longer life and improved exhaust efficiency.

The present invention is not limited to the embodiment described above. For example, the rotor has an H-shaped vertical section in the embodiment, but may have an inverted U-shaped vertical section by providing a support member at an upper end portion. Further, the gas bearing is not limited to the dynamic pressure gas bearing as in the embodiment, and the rotor of the motor may have an outer diameter smaller than that of the support shaft. In addition, the arrangement of gas bearings and motors,
It is not limited to the embodiment.

In addition, the present invention is not limited to the illustrated example described above, and various modifications can be made without departing from the spirit of the present invention.

[0023]

As described in detail above, the present invention focuses on the point that an inert gas for cooling a bearing is supplied to a gas bearing in a turbo-type vacuum exhaust device using a gas bearing.
The inert gas, which has been heated to a high temperature after the cooling operation, can be passed along the inner peripheral surface of the rotor to heat the rotor. For this reason, the gas to be compressed such as the etching gas flowing along the rotor can be heated without providing a heating mechanism such as a heater, and the adhesion of the reaction product in the flow path of the gas to be compressed can be performed with a simple mechanism. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic overall vertical sectional view of a turbo-type evacuation apparatus according to an embodiment of the present invention.

FIG. 2 is an end view taken along line AA of the rotor in FIG. 1;

FIG. 3 is an end view taken along line BB of the housing in FIG. 1;

FIG. 4 is a detailed view of a main part in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Rotor 11 ... Rotor blade (circumferential pump) 2 ... Support shaft 31 ... Dynamic pressure gas bearing (journal bearing) 32 ... Dynamic pressure gas bearing (thrust bearing) 4 ... Motor 5 ... Housing 53 ... Suction port 54 ... Exhaust port 8 ... Inert gas circulation route

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F04D 19/04

Claims (1)

(57) [Claims] 1. A housing, a rotor housed inside the housing and having a rotor blade provided on an outer peripheral surface, a support shaft having one end integrally attached to the rotor, and a support shaft and the housing. A gas bearing interposed therebetween and rotatably supporting the support shaft at the other end side; and a motor for rotating the support shaft. To move the gas along the rotor and exhaust the gas from the exhaust port.Inert gas is introduced into the housing from outside the housing, and the introduced inert gas is
An inert gas configured to pass through a motor and a gas bearing to be heated, and then pass the heated inert gas at least along the inner peripheral surface of the rotor to heat it and discharge it to the outside of the housing. A turbo-type vacuum evacuation device comprising a circulation path.