JP2003269373A - Vacuum pump system and rotating speed control method of vacuum pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum pump system, and a rotating speed control method of a vacuum pump generating no beat and low frequency vibration by unifying rotating speeds of rotary bodies even when a plurality of turbo molecular pumps are arranged. <P>SOLUTION: A rotation signal of a motor 121A in the turbo molecular pump 101A is outputted as a synchronizing signal 15 from a controller 12A as the master side. While, a PLL circuit (Phased Locked Loop) being a phase control circuit is built in a controller 12B as the slave side, and the synchronizing signal 15 outputted from the controller 12A is inputted. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum pump system and a method for controlling the rotation speed of a vacuum pump, and in particular, even when a plurality of turbo molecular pumps are arranged, the rotation speed of the rotating body is made to match. The present invention relates to a vacuum pump system that does not generate low-frequency vibrations and a method for controlling the rotation speed of a vacuum pump.

[0002]

2. Description of the Related Art With the recent development of electronics,
Demand for semiconductors such as memories and integrated circuits is rapidly increasing. These semiconductors are manufactured by doping a semiconductor substrate of extremely high purity with impurities to give electric properties, or by etching to form a fine circuit on the semiconductor substrate.

These operations must be carried out in a high vacuum chamber to avoid the influence of dust in the air. A vacuum pump is generally used to evacuate the chamber, but a turbo molecular pump, which is one of the vacuum pumps, is often used from the viewpoints of particularly small residual gas and easy maintenance.

In the semiconductor manufacturing process, there are many processes in which various process gases are applied to the semiconductor substrate. The turbo molecular pump not only evacuates the chamber, but also exhausts these process gases from the chamber. Also used to do.

Further, the vacuum pump prevents refraction of the electron beam due to the presence of dust or the like in equipment such as an electron microscope, so that the environment inside the chamber accommodating the electron microscope is set to a high vacuum state. Is also used.

As described above, the vacuum pump is widely used in various fields, but recently, in the field of semiconductor manufacturing, it is planned to manufacture a larger semiconductor wafer, and in the field of electron microscopes, the vacuum pump is larger than ever. There are many opportunities for electron microscopes and the like to be made into devices and equipment to be added.

In such a case, a plurality of vacuum pumps may be used as shown in the overall system simplified configuration diagram of FIG. In FIG. 4, vacuum pumps 10A and 10B are connected to the chamber 3 of the equipment to be sucked and depressurized.

In addition, between the vacuum pumps 10A, 10B and the chamber 3 of the equipment to be sucked and depressurized,
Actually, a valve such as an on-off valve and a damper for absorbing vibration are respectively present, but they are omitted for simplification.

The vacuum pumps 10A and 10B are, for example, turbo molecular pumps. And this vacuum pump 10A,
10B is controlled by controllers 12A and 12B, respectively. A vertical sectional view of the turbo molecular pump is shown in FIG.

In FIG. 5, a turbo molecular pump 101 is shown.
Has a suction port flange 1a formed on the upper end of a cylindrical outer cylinder 1c. Inside the outer cylinder 1c, a plurality of rotor blades 102 by turbine blades for sucking and exhausting gas
The rotating body 103 is formed by forming a, 102b, 102c ...

A rotor shaft 11 is provided at the center of the rotating body 103.
3 is attached, and the rotor shaft 113 is levitationally supported in the air and its position is controlled by, for example, a so-called 5-axis control magnetic bearing. The upper radial electromagnet 104 is
Four electromagnets are arranged in pairs on the X axis and the Y axis.

An upper radial sensor 107 composed of four electromagnets which are close to and correspond to the upper radial electromagnet 104.
Is provided. The upper radial sensor 107 is configured to detect the radial displacement of the rotor shaft 113 and send it to the controller 12.

In the controller 12, based on the displacement signal detected by the upper radial sensor 107, the upper radial electromagnet 104 is passed through a compensation circuit having a PID adjusting function.
Is controlled to adjust the radial position on the upper side of the rotor shaft 113.

The rotor shaft 113 is made of a material having a high magnetic permeability (such as iron).
And the like, and is attracted by the magnetic force of the upper radial electromagnet 104. Such adjustment is performed independently in the X-axis direction and the Y-axis direction.

Further, the lower radial electromagnet 105 and the lower radial sensor 108 are arranged similarly to the upper radial electromagnet 104 and the upper radial sensor 107, and the rotor shaft 113 is arranged.
The lower radial position is adjusted in the same manner as the upper radial position.

Further, the axial electromagnets 106A, 106B
However, the disk-shaped metal disks 111 provided under the rotor shaft 113 are vertically sandwiched. The metal disk 111 is made of a high magnetic permeability material such as iron. An axial sensor 109 is provided to detect the axial displacement of the rotor shaft 113, and the axial displacement signal is sent to the controller 12.

Axial electromagnets 106A and 106B are then provided.
Is the P of the controller 12 based on this axial displacement signal.
Excitation control is performed via a compensation circuit having an ID adjusting function. The axial electromagnet 106A attracts the metal disk 111 upward by magnetic force, and the axial electromagnet 1
06B sucks the metal disk 111 downward.

As described above, the controller 12 appropriately adjusts the magnetic force exerted by the axial electromagnets 106A and 106B on the metal disk 111 to magnetically levitate the rotor shaft 113 in the axial direction and hold it in the space in a non-contact manner. It has become.

The motor 121 is provided with a plurality of magnetic poles which are circumferentially arranged so as to surround the rotor shaft 113. Each magnetic pole is controlled by the controller 12 so as to rotationally drive the rotor shaft 113 via an electromagnetic force acting between the magnetic pole and the rotor shaft 113.

A rotation speed sensor 110 is attached to the lower end of the rotor shaft 113. Controller 12
Is adapted to detect the rotational speed of the rotor shaft 113 based on the detection signal of the rotational speed sensor 110.

Also, for example, a phase sensor (not shown) is attached near the lower radial sensor 108 to detect the phase of rotation of the rotor shaft 113. In the controller 12, the phase sensor and the rotation speed sensor 11
The position of the magnetic pole is detected by using the detection signal of 0 together.

[0022]

By the way, when a plurality of turbo molecular pumps (two turbo molecular pumps 101A and 101B) are used as vacuum pumps as described above, conventionally, the controller 12A and the controller 12B are different from each other. Each is controlled independently. On the other hand, the rotation speed is set, for example, at the rated rotation speed of 48,000 rpm (80
It is possible with an accuracy of several Hz for 0 Hz).

Therefore, even when the turbo molecular pump 101A and the turbo molecular pump 101B are set to the same rated rotation speed, the turbo molecular pump 101A side is actually operated at 48,000 rpm (800 Hz), while the turbo molecular pump 101A is operated. 48,060 rpm (8
There was a case where there was a slight difference in both rotation speeds such as the operation at 01 Hz).

In this case, a beat occurs due to the difference of 1 Hz between the rotational speeds of the two, and due to this beat, low-frequency vibrations may be generated in the turbo molecular pumps 101A and 101B. This vibration causes the turbo molecular pump 10
If it is transmitted to the chamber 3 side from 1A and 101B, there is a possibility that it may affect the measurement of the electron microscope and the like housed in the chamber 3 and the manufacturing of semiconductors.

The frequency of this beat is not uniform depending on the combination of the capacity and model of the turbo molecular pump to be arranged, and once the beat occurs, it is technically difficult to eliminate the beat. . Therefore, it is desirable not to generate a beat.

The present invention has been made in view of such conventional problems. Even when a plurality of turbo molecular pumps are provided, by matching the rotational speeds of the rotating bodies, beats and low-frequency vibrations are generated. It is an object of the present invention to provide a vacuum pump system and a method for controlling the rotation speed of the vacuum pump, which does not generate the noise.

[0027]

Therefore, the present invention has a built-in rotary blade and a motor for rotationally driving the rotary blade, and is installed in parallel with the equipment to be sucked in order to suck gas from the equipment to be sucked. A vacuum pump system comprising N vacuum pumps and a controller for controlling the rotation of the motor, wherein one of the controllers is a master controller and the rotation signal of the motor is extracted from the master controller. The rotation signal extracting means and the synchronization means for synchronizing the rotation signal extracted by the rotation signal extracting means with N-1 units other than the master controller as slave controllers.

The controller is linked to synchronize with the rotation of the motor. That is, the rotation signals of the slave controllers are matched based on the rotation signals extracted from the master controller. As a result, the rotation speeds and phases of the motors of the N vacuum pumps match.

By synchronously operating the vacuum pump, no beat occurs and low frequency vibration does not occur. Therefore, it is possible to use a plurality of vacuum pumps even for applications such as electron microscopes where vibration is disliked.

Further, according to the present invention, a plurality of vacuum pumps each having a rotary vane and a motor for rotationally driving the rotary vane are installed in parallel with the equipment to be sucked in order to suck gas from the equipment to be sucked. And a controller for controlling rotation of the motor, wherein the vacuum pump system comprises a synchronization signal generating means for generating and outputting a predetermined synchronization signal, and the predetermined synchronization signal input from the synchronization signal generating means. And a synchronizing means for synchronizing the rotation of the motor.

The rotation speed and phase of each motor are simultaneously adjusted based on the predetermined synchronization signal generated by the synchronization signal generating means, and as a result, the rotation speed and phase of each motor match.
Since the synchronization signal is created based on, for example, a crystal oscillator, the control accuracy can be further enhanced. Therefore, no beat occurs and low-frequency vibration does not occur. By this,
The same effect as that of claim 1 can be obtained.

Further, the present invention is a method for controlling the number of revolutions of a vacuum pump, comprising a rotary blade and a motor for rotationally driving the rotary blade, and sucking gas from the suction target equipment, the suction target equipment. A plurality of vacuum pumps installed side by side,
A controller for controlling rotation of the motor is provided, and the number of rotations of the motor is controlled to be the same.

It is not always necessary to match the rotation speed and the phase of the motor at the same time. If only the rotation speeds of the motors of all the vacuum pumps are matched, beats can be prevented and low-frequency vibration can be suppressed.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below. FIG. 1 shows an overall system configuration diagram of the first embodiment of the present invention. The same elements as those in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted. Further, an example in which two turbo molecular pumps are provided in each of the following embodiments is shown, but the same applies when three or more turbo molecular pumps are provided.

In FIG. 1, the rotation signal of the motor 121A in the turbo molecular pump 101A is output as the synchronization signal 15 from the controller 12A on the master side. On the other hand, the controller 12B on the slave side has a PLL circuit (Phase Lock) which is a phase control circuit.
ed Loop) is built in, and the synchronization signal 15 output from the controller 12A is input.

Next, the operation of the first embodiment of the present invention will be described. FIG. 2 shows the motor 121 input to the PLL circuit.
The synchronization signal 15 which is the rotation signal of A and the motor 121
The state of the rotation drive signal with respect to the motor 121B in the controller 12B created so that it may synchronize with the rotation signal of A is shown.

That is, the PLL circuit detects the rising or falling of the rotation signal of the motor 121A, and the controller 1 on the slave side with respect to the detected phase.
Processing for matching the phases of the rotation drive signals for the 2B motor 121B is performed. Then, the rotation drive signal whose rotation speed and phase are matched is sent from the controller 12B to the motor 1
21B, and the motor 121B is rotationally controlled.

As a result, the motor 121A and the motor 121
The rotation number and the phase match the rotation of B. Therefore, no beat occurs and low-frequency vibration does not occur. This makes it possible to use a plurality of turbo molecular pumps even for applications such as electron microscopes where vibration is disliked.

However, the rotational speed and the phase do not have to coincide with each other at the same time, and if only the rotational speeds coincide with each other, the beat can be prevented.

Next, a second embodiment of the present invention will be described. FIG. 3 shows an overall system configuration diagram of the second embodiment of the present invention. The same elements as those in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 3, both the controller 12A and the controller 12B have built-in PLL circuits. The synchronization signal 19 generated from the reference oscillator 17 is input to each PLL circuit of the controller 12A and the controller 12B. The reference oscillator 17 is composed of, for example, a crystal oscillator.

According to such a configuration, in each PLL circuit, the rotation speed and the phase of the rotation driving signal for the motor 121A and the rotation driving signal for the motor 121B are simultaneously adjusted based on the same input synchronizing signal 19.

Since the rotation speed and the phase are controlled by the reference oscillator 17 based on the crystal oscillator, the control accuracy can be further enhanced. Therefore, no beat occurs and low-frequency vibration does not occur. As a result, the same effect as that of the first embodiment of the present invention can be obtained.

[0044]

As described above, according to the present invention, the rotation signal of the slave controller is matched with the rotation signal of the master controller. Match. By operating the vacuum pump synchronously, no beat occurs and low-frequency vibration does not occur.

[Brief description of drawings]

FIG. 1 is an overall system configuration diagram of a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a master synchronization signal and a slave rotation signal input to a PLL circuit.

FIG. 3 is an overall system configuration diagram of a second embodiment of the present invention.

[Figure 4] Simplified configuration diagram of the entire system

FIG. 5 is a vertical sectional view of a turbo molecular pump.

[Explanation of symbols]

3 chambers 10A, 10B vacuum pump 12A, 12B controller 15, 19 Sync signal 17 Reference oscillator 101A, 101B Turbo molecular pump 102 rotor 103 rotating body 104 upper radial electromagnet 105 Lower radial electromagnet 106A, 106B axial electromagnet 107 Upper radial sensor 108 Lower radial sensor 109 Axial sensor 110 speed sensor 111 metal disc 113 rotor shaft 121A, 121B motor

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // F04D 19/04 F04D 19/04 HF term (reference) 3H021 AA06 AA08 BA01 BA11 BA20 CA04 CA07 DA04 DA21 EA07 3H022 AA01 BA03 BA07 CA06 CA48 CA50 DA09 3H031 DA01 DA02 DA07 EA12 EA13 EA15 FA40 3H045 AA06 AA09 AA16 AA21 AA26 AA31 AA38 AA39 BA01 BA28 BA31 BA38 CA09 CA21 DA05 DA31 EA26 EA34

Claims (3)

[Claims] 1. N vacuum pumps, which have a rotary blade and a motor for driving the rotary blade to rotate, are arranged in parallel with the suction target equipment for sucking gas from the suction target equipment, A vacuum pump system comprising a controller for controlling the rotation of a motor, wherein one of the controllers is a master controller, a rotation signal extracting means for extracting a rotation signal of the motor from the master controller, and the master controller. A vacuum pump system comprising: N-1 units other than the above as slave controllers, and synchronization means for synchronizing with the rotation signal extracted by the rotation signal extraction means. 2. A plurality of vacuum pumps each having a rotary vane and a motor for rotationally driving the rotary vane, arranged in parallel with the target equipment to be sucked for sucking gas from the target equipment to be sucked, and the motor. A vacuum pump system including a controller for controlling the rotation of the synchronization signal generating means for generating and outputting a predetermined synchronization signal, and the synchronization signal generating means for synchronizing with the predetermined synchronization signal input from the synchronization signal generating means. A vacuum pump system comprising: a synchronization means for synchronizing the rotation of a motor. 3. A plurality of vacuum pumps each having a rotary blade and a motor for driving the rotary blade to rotate, the plurality of vacuum pumps provided in parallel with the suction target equipment for sucking gas from the suction target equipment, and the motor. And a controller for controlling the rotation of the motor, wherein the number of rotations of the motor is all controlled to be the same.