JPH11193793A - Turbo molecular pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbo molecular pump ensuring to raise the temperature of the passage leading to the pump exhaust port with low thermal energy after completing compression at the exhaust portion composed of a rotor and a stator within a pump casing. SOLUTION: A turbo molecular pump is provided with an exhaust portion (defined by a blade exhaust portion L1 and a channel exhaust portion L2 ) formed of a rotor R and a stator S within a pump casing 1, and an exhaust port 20 communicated with an exhaust side of the exhaust portion. The exhaust port 20 is composed of an exhaust port forming member as a part different from the pump casing 1. The exhaust port 20 extends to the position in the vicinity of the exhaust side of the exhaust portion within the pump casing 1 and its temperature is increased by external heating means (heater 17).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbo-molecular pump in which exhaust is performed by a high-speed rotating rotor.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view showing an example of the structure of a conventional turbo-molecular pump of this kind. As shown, the turbo molecular pump comprises an exhaust consisting configured blade pumping section L ₁ and groove pumping section L ₂ by the rotor R and the stator S in the casing 1, the exhaust of the groove pumping section L ₂ The side communicates with the exhaust port 20 of the casing 1. When a turbo-molecular pump having such a structure is used in a semiconductor manufacturing apparatus or the like and a process gas is flowed, the following problems occur.

[0003] The gap between the rotor R and the stator S is closed by the adhesion of the sublimable reaction product, and the rotor R that has been rotating is restrained and stopped, and the compression in the blade exhaust portion L ₁ and the groove exhaust portion L ₂ is prevented. Passage to exhaust port 20 after completion (groove exhaust portion L
_The sublimable reaction product adheres and accumulates in the passage connecting the exhaust side of the _second and the exhaust port 20), closes the passage, increases the back pressure in the pump, and stops the overload of the drive motor 6.

[0004] The sublimation reaction product becomes a gas phase or a solid phase depending on the temperature and its partial pressure, and tends to be solidified in an environment having a lower temperature or an environment having a higher partial pressure, that is, an environment having a higher absolute pressure. In the turbo-molecular pump having the above-described structure, the sublimation reaction products are likely to be sequentially attached to the blade exhaust portion L ₁ , the groove exhaust portion L ₂ , and the exhaust port 20. Therefore, conventionally, the heater 15 or the heater 1 is provided outside the casing 1 or the exhaust port 20.
6, and the entire pump was heated. Note that a description of the entire turbo-molecular pump will be omitted later, since it will be described in detail later.

[0005]

Against INVENTION Problems to be Solved The sublimable reaction product actually heating is required parts exhaust side of the blade pumping section L ₁ and groove pumping section L _2, blade pumping section L ₁ and groove is compressed by the exhaust portion L ₂ is a passageway to the exhaust port 20 of the pump after completion. Conventionally, as described above, the outside of the casing 1 and the exhaust port 2
Since the heater 15 and the heater 16 were attached to 0 and the entire pump was heated, a large amount of heat was required. As a result, there was a limit to the temperature rise of the passage.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and reliably raises the temperature of a passage to a pump exhaust port after a compression is completed in an exhaust portion including a rotor and a stator in a pump casing with a small amount of heat. It is an object of the present invention to provide a turbo molecular pump that can be used.

[0007]

According to a first aspect of the present invention, there is provided an exhaust portion including a rotor and a stator inside a pump casing, and an exhaust port communicating with an exhaust side of the exhaust portion. In the turbo-molecular pump provided with the above, the exhaust port is formed as a separate part from the pump casing, and is extended to near the exhaust side of the exhaust section in the pump casing, and the temperature is raised by external heating means. And

[0008] The invention described in claim 2 is the first invention.
In the turbo-molecular pump described in the above paragraph, the exhaust part constituted by the rotor and the stator comprises a blade exhaust part and a groove exhaust part.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the structure of the turbo-molecular pump of the present invention. This turbo-molecular pump includes a rotor (rotating part) R and a stator (fixed part) S. The stator (fixed part) S is the pump casing 1
, The base 2 and the fixed cylindrical portion 3 are integrally formed mainly,
The rotor R is mainly composed of a main shaft 4 and a rotary tubular part 5. Blade pumping section L ₁ and groove pumping section L ₂ is formed in the interior of the pump casing 1 by the rotor (rotating part) R and a stator (fixed part) S.

A drive motor 6 is provided between the main shaft 4 and the fixed cylindrical portion 3.
Upper and lower radial bearings (magnetic bearings) 7 and lower radial bearings (magnetic bearings) 8 are provided on the upper and lower sides thereof, and the lower and upper electromagnets 10a, 10b provided on the target disk 9 and the stator S side below the main shaft 4. Is disposed. With such a configuration, the rotor R rotates at high speed under active control of five axes.

On the outer peripheral portion of the upper portion of the rotary cylindrical portion 5, a rotating blade 1 is provided.
2 are integrally provided to form an impeller. On the inner surface of the pump casing 1, fixed blades 13 alternately arranged with the rotating blades 12 are provided. The fixed blade 13 is pressed from above and below by the upper and lower fixed blade spacers 14 at its edge, and is clamped and fixed between the upper end of the thread groove spacer 19 and the step 1 a formed on the upper inner surface of the pump casing 1. .
By interaction with a fixed blade 13 which is stationary and the rotating blades 12 rotating at a high speed constituting the blade pumping section L ₁ which performs exhaust.

Furthermore, the groove pumping section L ₂ are provided on the lower blade pumping section L _1. That is, the rotary cylindrical part 5 is provided with a screw part 18 having a screw groove 18a formed on the outer peripheral surface so as to surround the fixed cylindrical part 3, while the stator S has the screw part 1
A thread groove portion spacer 19 surrounding the outer periphery of 8 is arranged. Screw groove of the groove pumping section L ₂ are threaded portion 18 rotated at a high speed 1
Exhaust is performed by the drag action of 8a.

Exhaust port constituting member 21 constituting exhaust port 20
The cylindrical, has dimensions its tip as shown to extend to the exhaust side near the groove pumping section L _2, which is and a structure in which a flange 21a is formed in the intermediate portion. The exhaust port constituting member 21 constituting the exhaust port 20 is configured as a separate component from the casing 1, and is inserted and fixed in an exhaust port insertion hole formed in the casing 1. Further, the exhaust port constituent member 21 comes into contact with the casing or the fixed cylindrical portion only at the flange 21a portion, and is heated and heated by the heater 17 provided at the flange 21a portion.

Since the exhaust port component 21 is small and has a small heat capacity, the exhaust port component 21 can be heated and heated even if the output heat capacity of the heater 17 is small. This is composed of a member passage to the gas from the exhaust side of the groove pumping section L ₂ is actually discharged to the outside constitute the exhaust port 20, and from being Atsushi Nobori by the heater 17, the passage The sublimation reaction product does not adhere to or hardly adheres to the substrate.

In the above embodiment, the blade exhaust portion L
Having described the broad turbomolecular pump as an example with ₁ and groove pumping section L _2, the present invention is not limited to such a wide area turbo-molecular pump, and short rotor inside the pump casing Naturally, the present invention can be applied to a turbo molecular pump in which an exhaust portion is configured by a stator.

The position at which the heater 17 for heating the member constituting the exhaust port 20 is not limited to the flange 21a, and the heating means is not limited to the heater. Any means may be used as long as it heats the exhaust port constituent member 21 constituting the part 20.

[0017]

As described above, according to the present invention,
The exhaust port is formed as a separate component from the pump casing, and is extended to the vicinity of the exhaust side of the exhaust section in the pump casing, and the temperature is raised by an external heating means, so that the following excellent effects are obtained. Can be

(1) The temperature of the passage to the exhaust port of the pump after the end of the compression in the exhaust portion constituted by the rotor and the stator can be reliably raised with a small amount of heat. The product does not adhere and accumulate, closing the passage and increasing the back pressure in the pump. Therefore, the drive motor does not stop overloading.

(2) Since the temperature of the exhaust port constituent member can be raised with a small amount of heat as described above, not only the energy consumption for raising the temperature is small, but also the processing apparatus using a turbo molecular pump. It is possible to provide a turbo-molecular pump that can maintain the entire vacuum for a long time and can further reduce damage to products during processing.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of a turbo-molecular pump according to the present invention.

FIG. 2 is a cross-sectional view showing the structure of a conventional turbo-molecular pump.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Pump casing 2 Base 3 Fixed cylindrical part 4 Main shaft 5 Rotating cylindrical part 6 Drive motor 7 Upper radial bearing 8 Lower radial bearing 9 Target disk 10a, b Electromagnet 11 Axial bearing 12 Rotary wing 13 Fixed wing 14 Fixed wing spacer 15 Heater Reference Signs List 16 heater 17 heater 18 thread portion 19 thread groove spacer 20 exhaust port 21 exhaust port component member R rotor S stator L ₁ blade exhaust section L ₂ groove exhaust section

Claims (2)

[Claims] 1. A turbo-molecular pump having an exhaust portion formed by a rotor and a stator inside a pump casing, and an exhaust port communicating with the exhaust side of the exhaust portion, wherein the exhaust port is a separate component from the pump casing. And a turbo-molecular pump extending to near the exhaust side of an exhaust portion in the pump casing and being heated by an external heating means. 2. The turbo-molecular pump according to claim 1, wherein the exhaust part constituted by the rotor and the stator comprises a blade exhaust part and a groove exhaust part.