JP2001173558A - Evacuation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an evacuation system capable of reducing the cost by reducing the space as the whole, and simplifying piping construction work. SOLUTION: In this evacuation system having a vacuum chamber, a means for introducing gas into the vacuum chamber, a main pump for exhausting the vacuum chamber to be reduced in pressure to desired pressure, an auxiliary pump provided on the trailing side of the main pump, and a pipe for connecting the above members, the outside diameter of a connecting pipe connecting between the main pump and the auxiliary pump is 1/2 inch (12.7 mm) or less, and the length of the connecting pipe and the capacity of the auxiliary pump are combined so that the back pressure of the main pump is 5 Torr or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum exhaust system used in, for example, a semiconductor manufacturing process, and more particularly to a vacuum exhaust system capable of exhausting a relatively large flow rate of gas from a vacuum processing chamber or the like.

[0002]

2. Description of the Related Art Conventional semiconductor manufacturing apparatuses and liquid crystal manufacturing apparatuses generally include, for example, a vacuum chamber for performing an etching process, a CVD process, and the like, a process gas exhausted from the vacuum chamber, and a vacuum chamber. From a vacuum pump to reduce the pressure to a desired pressure. As the vacuum pump, a roots-type vacuum pump or the like having an ultimate pressure in a medium vacuum region is generally used, but when a higher degree of vacuum is required, a turbo-type vacuum pump such as a turbo-molecular pump is used. A vacuum pump, such as a Roots type dry pump, that reaches the middle vacuum region as the ultimate pressure, should be installed on the downstream side of the main pump as an auxiliary pump, and the main pump back pressure should be evacuated to below the allowable back pressure by the auxiliary pump. Is widely practiced. The main pump and the auxiliary pump are connected by a pipe, and a necessary valve device is arranged in the pipe. As the turbo type vacuum pump referred to here, there are a turbo molecular pump and a molecular drag pump in which the ultimate pressure is in an ultra-high vacuum region and exhaustion to atmospheric pressure is impossible.

[0003] The auxiliary pump is usually arranged near the main pump. However, in some cases, the auxiliary pump is installed at a place away from the main pump or on a different floor. Auxiliary pump pumping speed (L
/ Min), the pumping speed (L /
sec) and the pumping speed ((L / min)) of the auxiliary pump is generally selected from about 0.2 to 1.0, and the auxiliary pump is relatively large and expensive.

[0004] The diameter of the pipe connecting the main pump and the auxiliary pump is usually 40 mm in inner diameter when the auxiliary pump is installed at a place away from the apparatus unit or on a different floor and the pipe length is long. The above thick piping is used. Even when the auxiliary pump is near the device unit and the pipe length is short, a pipe with an inner diameter of φ25 mm or more is used.

[0005]

In such a vacuum evacuation system, the pipe diameter and the performance of the auxiliary pump (especially the evacuation speed) are determined in consideration of the process gas flow rate, the pipe length, and the allowable back pressure of the main pump. I do. However, in general, the permissible back pressure of the main pump only means that continuous operation (without outputting an alarm and maintaining the rated rotation speed) is possible under the back pressure condition. For example, when a wide-range turbo-molecular pump is considered as the main pump, the exhaust performance at a low back pressure is actually reduced before the back pressure reaches the allowable back pressure as described later with reference to FIG. It cannot be maintained.

Accordingly, when the pump is used in an actual semiconductor manufacturing apparatus or liquid crystal manufacturing apparatus, a sufficient margin must be provided for the allowable back pressure so that the pumping performance can be sufficiently exhibited. As a result, the pipe diameter becomes large.

However, in an exhaust system using such a large-diameter pipe, especially when the pipe length is long, the pipe itself occupies an expensive space in a clean room, which increases the cost of factory equipment. There are issues.
Further, in the case of a conventional large-diameter pipe, as shown in FIG. 21B, straight pipes 4a, 4a having a length suitable for the site in advance and an elbow 4b constituting the bent portion B are prepared, and this is welded. However, this requires parts such as the elbow 4b, which increases the procurement and handling costs, and requires on-site inspections in advance. It was expensive. In the case of a large diameter, a bending tool such as a bender cannot be used, and even if it can be made, there is a problem of strength. This is the same also when using a flexible tube for the existing piping.

The present invention has been made in view of the above problems, and has as its object to provide a vacuum exhaust system capable of reducing costs through space saving as a whole and simplification of piping work.

[0009]

According to a first aspect of the present invention, there is provided a vacuum chamber, a means for introducing gas into the vacuum chamber, and a main pump for evacuating the vacuum chamber and reducing the pressure to a desired pressure. And an auxiliary pump installed on the downstream side thereof and a piping for connecting the auxiliary pump and the auxiliary pump, the outer diameter of a connecting pipe for communicating between the main pump and the auxiliary pump is 1/2 inch (12.7 m).
m) or less, wherein the length of the communication pipe and the capacity of the auxiliary pump are combined so that the back pressure of the main pump is 5 Torr or more.

[0010] In the following, the process of constituting the concept of the present invention will be described. The relationship between the pressure before and after the connecting pipe and the pipe diameter and length is generally represented by the following equation (1) when the connecting pipe is treated as a straight pipe.

(Equation 1) Q: Flow rate of gas introduced into the vacuum chamber (Pa · m
³ / S) D: Pipe inner diameter (m) L: Pipe length (m) P ₁ : Main pump back pressure (Pa) P ₂ : Auxiliary pump inlet pressure (Pa) Auxiliary pump exhaust speed S (m ³ / s) Then, P ₂ = Q
/ S η: viscosity coefficient (Pa) of gas introduced into vacuum chamber
・ S)

In a vacuum processing chamber, assuming a case where an 8-inch wafer is etched and the gas flow rate is set to a maximum flow rate of N ₂ gas, the back pressure of the main pump calculated by the equation (1) When the pipe length is set in consideration of the above, when the conventional inner diameter is 25 mm or 40 mm, the results are as shown in Table 1. In this case, it is sufficient that the allowable back pressure of the main pump is 2.0 Torr or more.

[0012]

[Table 1]

On the other hand, Table 2 shows the calculation results when the inside diameter of the pipe is reduced to φ10 mm, which is the same as that under the same conditions. Here, the term "current piping" refers to a piping method in which, for example, a pipe bending tool such as a bender is used and a pipe is bent at a site where the apparatus is installed or installed. For example, as shown in FIG. 20, the vacuum pumping system is installed up to the main pump 3 on the upper floor, and the auxiliary pump 5
Is installed downstairs, as shown in FIG. 21A, the bent portion B is bent with a bending tool such as a bender. Such processing is necessary in almost all cases, even if they are arranged on the same floor. When the outer diameter of the connecting pipe is 1/2 inch (12.7 mm) or less, a flexible tube may be used as a method of the existing pipe.

[0014]

[Table 2]

According to the results shown in Table 2, when the auxiliary pump is installed in the vicinity of a pipe length of 2 m from the apparatus, the pipe has an inner diameter of φ
To reduce the diameter to 10 mm or less, a main pump having an allowable back pressure of about 5 Torr is required. In addition, when the auxiliary pump is installed on the same floor at a location away from the apparatus, or installed on the upper floor and below the floor, and the pipe length is 5 m and 20 m, respectively, when the pipe diameter is reduced to 10 mm or less in inner diameter. It turns out that a main pump having an allowable back pressure of about 7 Torr and 15 Torr, respectively, is required.

Based on such recognition, the present invention combines a piping path with a small diameter that can be combined with a vacuum pump that can operate while maintaining the required back pressure assumed in that case. Configuration.

According to a second aspect of the present invention, there is provided a vacuum chamber, means for introducing a gas into the vacuum chamber, a main pump for exhausting the vacuum chamber and reducing the pressure to a desired pressure, and In the vacuum pumping system equipped with the auxiliary pump to be installed and the piping connecting them,
The outer diameter of the communication pipe that communicates between the main pump and the auxiliary pump is a value that can be constructed according to the present condition, and the length of the communication pipe and the capacity of the auxiliary pump are such that the back pressure of the main pump is 5 Torr or more. An evacuation system characterized by being combined as follows.

According to a third aspect of the present invention, there is provided a vacuum chamber, means for introducing a gas into the vacuum chamber, a main pump for exhausting the vacuum chamber and reducing the pressure to a desired pressure, and A method for constructing a vacuum pumping system including an auxiliary pump to be installed and a pipe connecting the pumps, wherein a connecting pipe communicating between the main pump and the auxiliary pump is constructed according to a conventional method. Is the construction method.

[0019] The invention described in claim 4 is the invention according to claim 1 or 2.
In the evacuation system according to the above, or the construction method according to claim 3, the main pump has a blade exhaust unit in which rotating blades and fixed blades are alternately arranged, and at least a part of the blade exhaust unit is 3. The exhaust system according to claim 1, wherein at least one of the surfaces of the rotating blade or the fixed blade facing each other is configured as a radial blade exhaust portion having irregularities.
A vacuum evacuation system according to claim 1 or a construction method according to claim 3.

By using such a new type of turbo vacuum pump, a stable exhaust operation can be performed even under relatively high back pressure conditions. The main pump may be a wide area type having a screw groove exhaust portion in addition to the blade exhaust portion.

The main pump may be provided integrally with a valve element for covering the intake port so as to be openable and closable and a valve drive mechanism for driving the valve element to open and close. This allows one valve device to serve both as an on-off valve (gate valve) and an opening adjustment valve (APC valve), so that the exhaust system around the chamber can be made compact.

A heater for raising the temperature of the pipe may be provided at an arbitrary position of the pipe connecting the main pump and the auxiliary pump. In the vacuum pumping system of the present invention, since the pressure between the main pump and the auxiliary pump is higher than that of the conventional vacuum pumping system,
Exhaust gas tends to accumulate as a solid product between the main pump and the auxiliary pump. Therefore, it is effective to increase the pipe temperature to a temperature equal to or higher than the saturated vapor pressure temperature of the exhaust gas in order to prevent blockage of the pipe.

Similarly, at least one of a cooling trap or a heating trap for removing products may be provided between the main pump and the auxiliary pump. Accordingly, before the exhaust gas is deposited on the pipe as a solid product, the exhaust gas can be forcibly cooled and solidified, or can be removed by causing a thermochemical reaction to be made into another substance.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a vacuum system according to the present invention will be described below with reference to FIG. This system includes, for example, a vacuum chamber 1 for performing etching or CVD processing, and a main pump (a main pump) for exhausting a process gas from inside the vacuum chamber 1 via a pipe 2 and depressurizing the vacuum chamber 1 to a desired pressure. (A turbo-type vacuum pump) 3, an auxiliary pump 5 installed on the downstream side of the main pump 3 via a connecting pipe 4 for exhausting the back pressure to an allowable back pressure or less, and disposed in these pipes 2 and 4. The flow control valve 6 and the opening / closing valves 7 and 8 are provided.

The connecting pipe 4 connecting the main pump 3 and the auxiliary pump 5 has an outer diameter of 1/2 inch or less, and the pipe length L is about 2 m. As described above, since the outer diameter of the pipe is small, the space occupied by the pipe is small, and the space in the expensive clean room can be effectively used.
Further, since the outer diameter of the pipe is small, the existing pipe can be used, and the equipment cost can be significantly reduced.

The allowable back pressure of the turbo vacuum pump 3 is at least 5 Torr. This turbo type vacuum pump 3
As shown in FIG. 2, the internal rotor (rotating part) R and a stator (fixed part) of the cylindrical pump casing 10 S is accommodated, axially blade pumping section L ₁ and the radial vanes therebetween an exhaust portion L ₂ is constructed. Flanges 12a and 12b are formed at upper and lower ends of the pump casing 10, and a pipe 2 extending from a vacuum chamber 1 to be evacuated is connected to the upper flange 12a.

The stator S has a base 1 joined to a lower flange 12b so as to cover a lower portion of the pump casing 10.
4, a tubular fixed tubular portion 16 erected at the center thereof,
And a fixing portion of the axial blade exhaust portion L ₁ and the radial direction blade pumping section L _2, the exhaust port 17 is formed in the base 14. The rotor R includes a main shaft 18 inserted into the fixed cylindrical portion 16 and a rotating cylindrical portion 20 attached to the main shaft 18.
have.

On the outer peripheral surface of the main shaft 18 and the inner peripheral surface of the fixed cylindrical portion 16, a driving motor 22 for rotating the rotor R, an upper radial bearing 24, a lower radial bearing 26 for supporting the rotor R in a non-contact manner, and An axial bearing 28 is provided. The axial bearing 28 includes a target disk 28a at the lower end of the main shaft 18 and upper and lower electromagnets 28b on the stator S side.
have. With such a configuration, the rotor R is 5
It rotates at high speed while receiving active control of the shaft. Touch-down bearings 29a and 29b are formed at two upper and lower portions of the fixed cylindrical portion 16.

A disk-shaped rotor 30 is integrally formed on the outer periphery of the rotary tubular portion 20 of the axial blade exhaust part L ₁ , and a fixed blade 32 is provided on the inner surface of the pump casing 10.
And are arranged alternately. Each fixed wing 32
The edge is fixed by being fixed from above and below by a fixed wing spacer 34. The rotating wing 30 has an inner peripheral hub 30a.
An inclined blade (not shown) extending in the radial direction is radially provided between the outer peripheral portion and the frame 30b at the outer peripheral portion. I have.

The radial blade pumping section _{L 2,} the axial blade exhaust portion L
₁ is provided on the downstream side, that is downward, substantially in the same manner as the axial blade exhaust portion L _1, a disk-shaped rotary blade 36 is formed integrally with the outer periphery of the rotating tubular portion 20, the inner surface of the pump casing 10 The fixed wings 38 are provided alternately with the rotating wings 36. Each fixed wing 38 is fixed by being pressed from above and below by a fixed wing spacer 40 at its edge.

Each of the fixed wings 38 is formed in the shape of a hollow disk, and has a spiral shape (a spiral shape) extending between a central hole 42 and a peripheral edge portion 44 on its front and back surfaces as shown in FIG. Are provided, and a groove 48 is formed between the ridges 46. The spiral ridges 46 on the front surface, that is, the upper surface of each of the fixed blades 38 cause the gas molecules to move inward as shown by the solid arrow B with the rotation of the rotary blade 36 shown by the arrow A in FIG. 3A. Helical ridges 46 on the back surface, ie, the lower surface, of each fixed wing 38.
Is formed such that gas molecules flow outward as indicated by a dashed arrow C with the rotation of the rotary wing 36. Such a fixed wing 38 is usually formed as a half body, which is assembled via a fixed wing spacer 40 so as to alternate with the rotating wing 36, and then inserted into the casing 10.

[0032] With the above configuration, in the turbo vacuum pump of this embodiment, in the radial direction blade pumping section L _2, the rotation and the fixed blades 38 between the axially short span wings 3
6, a long exhaust path is formed in a zigzag manner from top to bottom. Therefore, there is provided a turbo vacuum pump having high exhaust / compression performance without increasing the length in the axial direction as a whole.

Hereinafter, the performance of a vacuum exhaust system using such a turbo type vacuum pump as the main pump 3 will be described.
This will be described with reference to FIG. Here, the allowable back pressure is 3.
A description will be given in comparison with a conventional vacuum pumping system using a conventional vacuum pump having a pressure of 0 Torr or less. In the figure,
3 is a configuration curve of a conventional evacuation system for a certain condition (P ₁ , D, η, Q). The conventional configuration range is a combination of the right (lower) area of the curve. Here, when the inside diameter of the pipe is reduced from D (φ25 mm or more) to D ′ (φ10 mm or less), the limit of the pipe length L of the conventional evacuation system is shortened and falls to the lower side of the figure (in the figure), and the vacuum The construction area of the exhaust system is further reduced.

Here, the same condition (P ₁ ′ (5.0
Configuration curve of the vacuum pumping system of the present invention in which the main pump 3 is a vacuum pump whose allowable back pressure with respect to D ′ (φ10 mm or less), η, Q) is P ₁ ′ (5.0 Torr or more). And the configuration range is the right (lower) region of the curve. As described above, when this turbo type vacuum pump is used, the allowable back pressure of the main pump is higher than that of the conventional vacuum exhaust system, so that the pipe length L is increased and the exhaust speed S of the auxiliary pump 5 is reduced. (→→ in the figure).

As shown in FIG. 5, the turbo-type vacuum pump can be operated while maintaining the performance such as the exhaust speed and the ultimate vacuum degree even when the back pressure is 15 Torr. . On the other hand, the allowable back pressure is 3.0
In a conventional turbo-molecular pump having a pressure of Torr, as shown in FIG.
The pumping speed is greatly reduced as compared with the case of 3 Torr, which is not practical.

In particular, if the vacuum pumping system is configured in a region where the auxiliary pump pumping speed S is small, the cost reduction and space saving of the vacuum pumping system can be achieved in addition to the above-mentioned reduction of the pipe diameter. Another advantage is that the size of the auxiliary pump 5 is reduced, so that the auxiliary pump 5 is not installed in a separate utility space such as downstairs, but is located beside the device unit or the main pump 3.
(In the equipment unit), and as shown in FIG. 7, it can be placed in a relatively narrow installation floor 9 to greatly reduce the space or unitize the exhaust system. Can be.

FIG. 8 shows a turbo type vacuum pump according to another embodiment which can be used for the main pump 3 of the vacuum evacuation system according to the present invention. Here, a spiral ridge 50 is provided on the rotor side. Is formed. That is, it is formed on the outer edge of the front and back surfaces of the rotary wing 36, the spiral groove 52 is formed therebetween, and the surface of the fixed wing 38 is formed flat. The spiral ridge 50 on the front surface, that is, the upper surface of each rotor 36, causes gas molecules to move outward as shown by the solid arrow B with the rotation of the rotor shown by the arrow A in FIG. 7A. It is formed to flow, while each rotor 3
The spiral ridge 50 on the back surface of 6, that is, the lower surface is formed such that gas molecules flow inward as indicated by the dashed arrow C with the rotation of the rotary blade 36.

The top to bottom Also in this embodiment, as with the previous case, the radial blade pumping section L _2, in a cross section including the axis of FIG. 2, between the fixed blade 38 and the rotating blades 36 in a zigzag Therefore, a turbo-type vacuum pump is provided which has high exhaust / compression performance without increasing the axial length as a whole.

Comparing this turbo-type vacuum pump with a conventional wide-range type turbo-molecular pump having a thread groove exhaust part,
There are the following advantages. That is, in the conventional screw groove exhaust portion, a clearance is formed in the radial direction between the rotor and the stator, so that elastic deformation when the rotor rotates, thermal deformation when the rotor temperature rises, and continuous rotation at a high temperature of the rotor. It is difficult to obtain stable performance because it tends to change with creep deformation due to driving. In contrast, in the radial blade pumping section L ₂ in the turbo vacuum pump of this embodiment, the clearance is formed axially between the two discs, the shaft and the casing, Ya resilient loading Less susceptible to temperature changes. Therefore, even if elastic deformation, thermal deformation, or creep deformation occurs, the clearance does not easily change. Therefore, stable performance can be maintained, and durability against overload operation is excellent.

FIG. 9 shows a modification of the turbo type vacuum pump shown in FIG. 2. This vacuum pump comprises a valve body 62 for opening and closing an intake port, and a valve drive for opening and closing the valve body 62. And a valve drive mechanism 64 is provided integrally with the pump body. This valve device can adjust the opening degree, and can be opened and closed with one valve device (gate valve)
And an opening adjustment valve (APC valve). In this way, by integrating the valve device and also serving as the opening adjustment valve, the exhaust system around the chamber can be made more compact.

[0041] 10 to 12 show another embodiment of a turbo vacuum pump, Fig. 10, a thread groove exhaust portion between the axial blade exhaust portion L ₁ and the radial blade pumping section L ₂ L ₃
, And a three-stage exhaust configuration. That is,
A screw groove portion 54 having a screw groove 54a is formed on the outer peripheral surface of the middle portion of the rotary cylindrical portion 20, and a screw groove exhaust portion spacer 56 is provided at a position on the stator side facing the screw groove portion 54, thereby enabling high-speed rotation of the rotor. Exhausts while dragging gas molecules. 11, is provided with a thread groove exhaust portion L ₃ on the downstream side of the radial blade pumping section L _2.

[0042] Figure 12 is also a form of embodiment in which a thread groove exhaust portion L ₃ on the downstream side of the radial blade pumping section L _2. The thread groove exhaust portion L ₃ is provided on the back side of the rotating tubular portion 20 constituting a radial blade pumping section L _2. That is, the inner side of the portion corresponding to the radial blade pumping section L ₂ of the rotating tubular portion 20, and a gap is formed between the outer surface of the fixed tubular portion 16 of the stator S, here, on the outer surface A thread groove exhaust portion sleeve 58 having a thread groove 54a formed therein is inserted. The thread groove exhaust sleeve 58 is fixed on the base 14 via a lower flange body 58a.

The thread groove 54a is formed so as to exhaust gas molecules upward from below by a drag action caused by the rotation of the rotor R. Thus, the gap between the bottom of the radial blade pumping section L ₂ of the rotating tubular portion 20 and raised between the thread groove exhaust portion sleeve 58, further thread groove exhaust portion sleeve 58 and the fixed tubular portion 16 Descends and exhaust port 17
Is formed. According to this embodiment, by providing the radial blade pumping section L ₂ and the thread groove exhaust portion L ₃ to overlap in the axial direction, without increasing the axial length as a whole, a higher A turbo-type vacuum pump having exhaust / compression performance is provided.

[0044] Figure 13 shows another embodiment of the present invention, not provided an axial blade exhaust portion, Turbo multistage all stages is constituted by the radial blade pumping section L ₂ 1 shows a vacuum pump. This embodiment has an effect that a high flow rate can be pumped in a region where the pressure is higher than the molecular flow region where a normal turbo molecular pump is used, as compared with the above-described combination type with the axial blade exhaust portion. Demonstrate.

[0045] Figure 14, in which the thread groove pumping section L ₃ provided downstream of the embodiment of FIG. 13, here, a groove exhaust portion sleeve during rotation cylindrical portion 20 and the fixed tubular portion 16 ( A second fixed cylindrical part) 60 is provided, and a spiral ridge 60a is formed on the outer surface of the second fixed cylindrical part, and a screw groove is formed between the rotary cylindrical part 20 and the groove exhaust part sleeve 60. forming an exhaust L _3. Thus, an exhaust passage that reciprocates in the axial direction is formed, and a compact and high-displacement pump can be configured.

FIG. 15 shows a turbo vacuum pump according to still another embodiment of the present invention, in which a groove exhaust portion L having a cylindrical screw groove portion 54 having a screw groove 54a at the front stage.
₃ is provided, it is provided with a radial blade pumping section L ₂ at the subsequent stage. In this embodiment, as compared to the combination of the axial blade exhaust portion L ₁ and the radial blade pumping section L ₂ shown in FIG. 2, the following effects. In other words, the axial exhaust portion exerts more performance in the molecular flow region, whereas the axial thread groove exhaust portion works effectively in the pressure region of about 1 to 1000 Pa, so that the viscous flow region closer to the atmosphere can be obtained. Operation becomes possible.

In the above description, the radial blade exhaust portion L
₂ includes a fixed wing 38 and a rotating wing 36 as shown in FIG. 16A.
Are formed with irregularities 46 and 50 of a predetermined shape on one side.
As shown in FIGS. 16B to 16D and FIGS.
May be located appropriately to 50 at least one of the opposing surfaces of the stationary blades 38 and rotating blades 36, also may be applied by changing the arrangement in each stage of the radial blade pumping section L _2.

FIG. 18 shows still another embodiment of the present invention. A heater 66 for increasing the temperature of a pipe is provided at an arbitrary position including an on-off valve 8 in a pipe connecting the main pump 3 and the auxiliary pump 5. Provided. Since the pressure between the main pump 3 and the auxiliary pump 5 in the vacuum pumping system of the present invention is higher than that of the conventional vacuum pumping system, the exhaust gas is easily deposited as a solid product between the main pump 3 and the auxiliary pump 5. In such a case, a situation such as blockage of the pipe is likely to occur. In order to prevent this, a heater is provided to increase the pipe temperature to a temperature equal to or higher than the saturated vapor pressure temperature of the exhaust gas.

FIG. 19 shows still another embodiment of the present invention, in which a product removing trap 68 is provided in the pipe 4 between the main pump 3 and the auxiliary pump 5.
This may be at least one of the cooling trap 68 and the heating trap. This makes it possible to remove components that easily solidify in the exhaust gas after forcibly cooling or causing a thermochemical reaction to separate them before being deposited as a solid product on the pipe.

In the above description, the pipe size between the main pump 3 and the auxiliary pump 5 is smaller than the outer diameter φ1 / 2 inch. However, the exhaust port diameter of the main pump 3, the intake port diameter of the auxiliary pump 5, and the other Depending on the size of the vacuum parts between the pumps 5, there may be a pipe portion larger than the outer diameter φ1 / 2 inch, and it is sufficient that the main pipe diameter is less than the outer diameter φ1 / 2 inch.

FIG. 20 shows still another embodiment of the present invention. In this vacuum evacuation system, from the vacuum chamber 1 to the main pump 3 is installed on the upper floor, and the auxiliary pump 5 is installed on the lower floor. ing. The communication pipe 4 connecting the main pump 3 and the auxiliary pump 5 has an outer diameter of φ1 / 2 inch or less, and the pipe length L is about 20 m. The connecting pipe 4 has one bent portion B, which is bent by a bending tool such as a bender. In this case, the allowable back pressure of the main pump 3 is about 15.0 Torr.

As the auxiliary pump 5, an oil rotary pump and a dry vacuum pump are generally used. Examples of the dry vacuum pump include a roots vacuum pump, a screw vacuum pump, a claw vacuum pump, a scroll vacuum pump, a screw groove vacuum pump, a piston vacuum pump, and a diaphragm vacuum pump. As a measure for promoting the miniaturization of the auxiliary pump 5, in particular, the piston type vacuum pump and the diaphragm type vacuum pump have a simple structure and the pump size can be extremely reduced.

In each figure, the main pump and the auxiliary pump are in a one-to-one combination, but a plurality of main pumps may be combined with the auxiliary pump.

[0054]

As described above, according to the present invention, the exhaust system is provided with a pipe path of a small-diameter pipe capable of combining pipes at the time of construction and a necessary back pressure assumed in that case. It is configured in combination with a vacuum pump that can be maintained and operated, so that the space occupied by the piping itself can be reduced and the construction work can be simplified, and the cost of the entire vacuum exhaust system can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration and arrangement of an embodiment of a vacuum evacuation system of the present invention.

FIG. 2 is a cross-sectional view showing one embodiment of a turbo type vacuum pump used in the vacuum evacuation system of the present invention.

3A is a diagram showing a main part of FIG. 2, and FIG. 3B is a sectional view thereof.

FIG. 4 is a graph showing the performance of the vacuum evacuation system of the present invention in comparison with a conventional example.

FIG. 5 is an evacuation velocity diagram of the evacuation system of the present invention.

FIG. 6 is an evacuation speed diagram of a conventional evacuation system.

FIG. 7 is a diagram showing another embodiment of the vacuum evacuation system of the present invention.

FIG. 8 is a view showing (a) a main part of another embodiment of a turbo type vacuum pump used in the vacuum evacuation system of the present invention;
(B) It is sectional drawing.

FIG. 9 is a sectional view of still another embodiment of a turbo type vacuum pump used in the vacuum evacuation system of the present invention.

FIG. 10 is a sectional view of still another embodiment of the turbo vacuum pump used in the vacuum evacuation system of the present invention.

FIG. 11 is a sectional view of still another embodiment of a turbo type vacuum pump used in the vacuum evacuation system of the present invention.

FIG. 12 is a sectional view of still another embodiment of a turbo vacuum pump used in the vacuum evacuation system of the present invention.

FIG. 13 is a cross-sectional view of still another embodiment of the turbo vacuum pump used in the vacuum evacuation system of the present invention.

FIG. 14 is a sectional view of still another embodiment of a turbo vacuum pump used in the vacuum evacuation system of the present invention.

FIG. 15 is a sectional view of still another embodiment of a turbo type vacuum pump used in the vacuum evacuation system of the present invention.

FIGS. 16A to 16D are cross-sectional views showing a modification of the method of forming irregularities of the turbo-molecular pump of the present invention.

FIGS. 17A to 17E are cross-sectional views showing another modification of the method of forming irregularities of the turbo-molecular pump of the present invention.

FIG. 18 is a diagram showing another embodiment of the vacuum evacuation system of the present invention.

FIG. 19 is a view showing still another embodiment of the vacuum evacuation system of the present invention.

FIG. 20 is a diagram showing still another embodiment of the vacuum evacuation system of the present invention.

FIG. 21 is an enlarged view showing a bent portion of a pipe;
(A) shows the case of the present invention, and (b) shows the conventional case.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Pipe 3 Main pump 4 Communication pipe 5 Auxiliary pump 6 Flow control valve 7, 8 On-off valve 9 Installation floor 10 Pump casing 12a, 12b Flange 14 Base 16 Fixed cylindrical part 17 Exhaust port 18 Main shaft 20 Rotating cylindrical part Reference Signs List 22 Drive motor 24 Upper radial bearing 26 Lower radial bearing 28 Axial bearing 28a Target disk 28b Electromagnet 29a, 29b Touchdown bearing 30 Rotating blade 30a Hub 30b Frame 32 Fixed blade 34 Fixed blade spacer 36 Rotating blade 38 Fixed blade 40 Fixed blade spacer 42 hole 44 peripheral part 46 ridge 48 groove 50 ridge 52 groove 54a groove 54 groove 56 groove exhaust part spacer 58 groove exhaust part sleeve 58a flange body 60 groove exhaust part sleeve 60a ridge 62 valve body 64 valve drive mechanism 66 heater 6 Trap L ₁ axial blade exhaust portion L ₂ radial blade pumping section L ₃ groove pumping section B bent portion R rotor S stator

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H031 DA00 DA01 DA02 DA06 DA08 EA00 EA06 FA01 FA37 3H076 AA16 AA21 AA38 BB34 BB38 BB43 CC07 CC51 CC94 CC95

Claims (4)

[Claims] 1. A vacuum chamber, means for introducing a gas into the vacuum chamber, a main pump for evacuating the vacuum chamber to reduce the pressure to a desired pressure, and an auxiliary pump installed on the downstream side, In a vacuum exhaust system provided with a pipe for connecting these, an outer diameter of a communication pipe for communicating between the main pump and the auxiliary pump is equal to or less than ｉｎ inch (12.7 mm), and a length of the communication pipe and the auxiliary pump Wherein the main pump back pressure is combined so that the back pressure of the main pump becomes 5 Torr or more. 2. A vacuum chamber, means for introducing gas into the vacuum chamber, a main pump for evacuating the vacuum chamber to reduce the pressure to a desired pressure, and an auxiliary pump installed on the downstream side, In a vacuum evacuation system provided with a pipe for connecting these, the outer diameter of the communication pipe for communicating between the main pump and the auxiliary pump is a value that can be constructed according to the present condition, and the length of the communication pipe and the auxiliary pump Wherein the main pump back pressure is combined so that the back pressure of the main pump becomes 5 Torr or more. 3. A vacuum chamber, means for introducing gas into the vacuum chamber, a main pump for evacuating the vacuum chamber to reduce the pressure to a desired pressure, and an auxiliary pump installed on the downstream side, A method for constructing a vacuum evacuation system provided with a pipe for connecting these, wherein a communication pipe for communicating between the main pump and the auxiliary pump is constructed according to the present condition. 4. The vacuum pumping system according to claim 1 or 2, or the construction method according to claim 3, wherein the main pump has a blade exhaust unit in which rotating blades and fixed blades are alternately arranged. And at least a part of the blade exhaust portion is configured as a radial blade exhaust portion having irregularities formed on at least one of opposing surfaces of the rotating blade or the fixed blade. The vacuum evacuation system according to claim 2 or the construction method according to claim 3.