Vacuum exhaust system and vacuum pump

Abstract

To provide a vacuum exhaust system that can achieve cost reduction, compactification, and / or improvement of the degree of freedom in piping design.SOLUTION: A vacuum exhaust system 10 is for exhausting process gas from a plurality of chambers 10-1 to 10-n. The vacuum exhaust system 10 comprises a plurality of turbo molecular pumps 100-1 to 100-n, a collecting pipe 14 for connecting the exhaust ports of the plurality of turbo molecular pumps in parallel, one or more dry pumps 16 connected to the collecting pipe 14, and chamber introduction valve devices 30-1 to 30-n that control the flow rate of the gas introduced into the plurality of chambers 10-1 to 10-n. A threshold value T for a process gas exhaust flow rate is set on the basis of the flow rates that the plurality of turbo molecular pumps 100-1 to 100-n can exhaust, and at least one of the introduction timing and / or flow rate of the gas is controlled by the chamber introduction valve devices 30-1 to 30-n so as not to exceed the exhaust flow rate threshold value T.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a vacuum evacuation system equipped with a vacuum pump such as a turbomolecular pump, and to a vacuum pump used in a vacuum evacuation system. [Background technology]

[0002] Generally, turbomolecular pumps are known as a type of vacuum pump. In these turbomolecular pumps, a motor in the pump body is energized to rotate rotors, which eject the gas molecules (gas molecules) of the gas (process gas) sucked into the pump body, thereby discharging the gas. Some turbomolecular pumps are equipped with heaters and cooling tubes to properly manage the temperature inside the pump.

[0003] Furthermore, in a vacuum exhaust system related to manufacturing equipment for semiconductors, flat panels, and the like (hereinafter referred to as "semiconductors, etc."), a plurality of turbo molecular pumps (TMPs) may be provided, for example, as disclosed in FIG. 1 of Patent Document 1. Here, as disclosed in Patent Document 1, a type in which one back pump (BP, also called "dry pump") is provided for a plurality of turbo molecular pumps is called, for example, a centralized exhaust type vacuum exhaust system (centralized exhaust system). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-227618 A Summary of the Invention [Problem to be solved by the invention]

[0005] A typical turbomolecular pump has a dependency on back pressure (secondary pressure) (called back pressure dependency), and when the back pressure exceeds a certain value (allowable back pressure), the intake pressure (intake port pressure) cannot be maintained. Also, even in a centralized exhaust system such as the one mentioned above, the back pressure of the turbomolecular pump must be kept below the allowable back pressure.

[0006] However, the maximum gas flow rate in a centralized exhaust system is estimated by multiplying the number of process chambers (also called "processing chambers," "processing chambers," "vacuum chambers," etc.) used in the manufacture of semiconductors, etc. by the maximum flow rate for each process chamber. In other words, if the maximum flow rate for each process chamber is Qmax and the number of process chambers is n, the maximum gas flow rate is calculated as Qmax x n. For this reason, in order to keep the back pressure of the turbomolecular pump below the allowable back pressure, it is necessary to increase the size of the back pump (dry pump) (increase the pumping speed), use piping with small conductance, or adopt a turbomolecular pump with excellent back pressure dependency, which tends to increase the cost of the exhaust system.

[0007] An object of the present invention is to provide a vacuum evacuation system that enables cost reduction, miniaturization, and / or increased freedom in piping design, and a vacuum pump used in the vacuum evacuation system. [Means for solving the problem]

[0008] (1) In order to achieve the above object, the vacuum pumping system according to the present invention comprises: 1. A vacuum pumping system for evacuating process gases from a plurality of process chambers, comprising: The vacuum pumping system includes: a plurality of first vacuum pumps; a collecting pipe that connects exhaust ports of the plurality of first vacuum pumps in parallel; one or more second vacuum pumps connected to the collecting pipe; a gas introduction amount control unit for controlling a flow rate of gas introduced into the plurality of processing chambers; Equipped with setting an exhaust flow rate threshold of the processing gas based on the exhaust flow rates of the first vacuum pumps; The gas introduction amount control means controls at least one of the gas introduction timing and flow rate so that the exhaust flow rate threshold is not exceeded. (2) In order to achieve the above object, the vacuum pump according to the present invention comprises: The vacuum pump is used as the first vacuum pump provided in the vacuum exhaust system. Effect of the Invention

[0009] According to the above-mentioned invention, it is possible to provide a vacuum evacuation system that enables cost reduction, miniaturization, and / or improvement in the freedom of piping design, and a vacuum pump used in the vacuum evacuation system. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is an explanatory diagram illustrating a schematic configuration of a vacuum pump and a vacuum evacuation system according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a circuit diagram of an amplifier circuit. [Diagram 3] 6 is a time chart showing control when a current command value is larger than a detection value. [Figure 4] 6 is a time chart showing control when a current command value is smaller than a detection value. [Diagram 5] FIG. 1A is an explanatory diagram that shows a schematic diagram of a centralized exhaust type vacuum exhaust system according to an embodiment, and FIG. 1B is an explanatory diagram that shows a schematic diagram of a distributed exhaust type vacuum exhaust system as a conventional example. [Figure 6] 1 is a graph showing an example of changes in the displacement of one turbo molecular pump. [Figure 7] FIG. 2 is a block diagram illustrating an exhaust stem control unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <Turbo Molecular Pump 100> Hereinafter, a vacuum exhaust system 10 according to an embodiment of the present invention and a vacuum pump that can be used in the vacuum exhaust system 10 will be described with reference to the drawings. First, Fig. 1 shows a vertical cross-sectional view of a turbomolecular pump 100 as a vacuum pump according to an embodiment of the present invention.

[0012] 1, turbo molecular pump 100 has an intake port 101 formed at the upper end of a cylindrical outer cylinder 127. Inside outer cylinder 127, rotor 103 is provided, which has a plurality of rotors 102 (102a, 102b, 102c, ...) that are turbine blades for sucking in and exhausting gas, formed radially on its periphery in multiple stages. Rotor shaft 113 is attached to the center of rotor 103, and rotor shaft 113 is supported in the air and its position is controlled by, for example, a five-axis controlled magnetic bearing.

[0013] The upper radial electromagnets 104 are arranged in pairs on the X-axis and the Y-axis. Four upper radial sensors 107 are provided adjacent to the upper radial electromagnets 104 and corresponding to each of the upper radial electromagnets 104. The upper radial sensors 107 are, for example, inductance sensors or eddy current sensors having conductive windings, and detect the position of the rotor shaft 113 based on the change in inductance of the conductive windings that changes according to the position of the rotor shaft 113. The upper radial sensors 107 are configured to detect the radial displacement of the rotor shaft 113, i.e., the rotating body 103 fixed thereto, and send the detected displacement to the control device 200.

[0014] In this control device 200, for example, a compensation circuit having a PID adjustment function generates an excitation control command signal for the upper radial electromagnet 104 based on a position signal detected by the upper radial sensor 107, and an amplifier circuit 150 (described later) shown in Figure 2 controls the excitation of the upper radial electromagnet 104 based on this excitation control command signal, thereby adjusting the upper radial position of the rotor shaft 113.

[0015] The rotor shaft 113 is made of a material with high magnetic permeability (iron, stainless steel, etc.) 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. The lower radial electromagnet 105 and the lower radial sensor 108 are arranged in the same manner as the upper radial electromagnet 104 and the upper radial sensor 107, and adjust the lower radial position of the rotor shaft 113 in the same manner as the upper radial position.

[0016] Furthermore, axial electromagnets 106A and 106B are arranged above and below a circular metal disk (also called an "armature disk") 111 provided at the bottom of rotor shaft 113. 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 rotor shaft 113, and an axial position signal is sent to control device 200.

[0017] In the control device 200, a compensation circuit having, for example, a PID adjustment function generates an excitation control command signal for each of the axial electromagnets 106A and 106B based on the axial position signal detected by the axial sensor 109, and the amplifier circuit 150 controls the excitation of the axial electromagnets 106A and 106B based on these excitation control command signals, so that the axial electromagnet 106A attracts the metal disk 111 upward by magnetic force and the axial electromagnet 106B attracts the metal disk 111 downward, thereby adjusting the axial position of the rotor shaft 113.

[0018] In this way, the control device 200 appropriately adjusts the magnetic force that the axial electromagnets 106A, 106B exert on the metal disk 111, magnetically levitating the rotor shaft 113 in the axial direction and holding it in a non-contact manner in space. The amplifier circuit 150 that controls the excitation of the upper radial electromagnets 104, the lower radial electromagnets 105, and the axial electromagnets 106A, 106B will be described later.

[0019] Meanwhile, motor 121 has a plurality of magnetic poles arranged circumferentially so as to surround rotor shaft 113. Each magnetic pole is controlled by control device 200 so as to rotate rotor shaft 113 via electromagnetic force acting between the magnetic pole and rotor shaft 113. Also, motor 121 incorporates a rotation speed sensor such as a Hall element, resolver, or encoder (not shown), and the rotation speed of rotor shaft 113 is detected by a detection signal from this rotation speed sensor.

[0020] Furthermore, 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. The control device 200 detects the position of the magnetic poles using the detection signals of both this phase sensor and the rotation speed sensor.

[0021] A plurality of fixed blades 123 (123a, 123b, 123c...) are disposed at small gaps (predetermined intervals) from the rotor blades 102 (102a, 102b, 102c...). The rotor blades 102 (102a, 102b, 102c...) are formed at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113 in order to transport exhaust gas molecules downward by collision with them.

[0022] Similarly, the fixed blades 123 are formed at an inclination at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and are arranged alternately with the stages of the rotor blades 102 toward the inside of the outer cylinder 127. The outer peripheral ends of the fixed blades 123 are supported in a state where they are inserted between a plurality of stacked stages of fixed blade spacers 125 (125a, 125b, 125c, etc.).

[0023] The fixed wing spacer 125 is a ring-shaped member and is made of metal such as aluminum, iron, stainless steel, copper, or an alloy containing these metals as components. An outer cylinder 127 is fixed to the outer periphery of the fixed wing spacer 125 with a small gap therebetween. A base portion 129 is disposed at the bottom of the outer cylinder 127. An exhaust port 133 is formed in the base portion 129 and communicates with the outside. Exhaust gas that enters the intake port 101 from the chamber (vacuum chamber, processing chamber) side and is transferred to the base portion 129 is sent to the exhaust port 133.

[0024] Furthermore, depending on the application of the turbo molecular pump 100, a threaded spacer 131 is disposed between the lower part of the fixed vane spacer 125 and the base part 129. The threaded spacer 131 is a cylindrical member made of metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals, and has a plurality of helical thread grooves 131a engraved on its inner peripheral surface. The helical direction of the thread groove 131a is the direction in which, when exhaust gas molecules move in the rotation direction of the rotor 103, the molecules are transported toward the exhaust port 133. A rotor lower cylindrical part 103b is suspended from the lower part of the rotor main body 103a on which the rotor vanes 102 (102a, 102b, 102c,...) of the rotor 103 are formed. The outer peripheral surface of the rotor lower cylindrical portion 103b is cylindrical and protrudes toward the inner peripheral surface of the threaded spacer 131, and is adjacent to the inner peripheral surface of the threaded spacer 131 with a specified gap therebetween. The exhaust gas transferred to the thread groove 131a by the rotor 102 and the fixed blades 123 is guided by the thread groove 131a and sent to the base portion 129. In this manner, the threaded spacer 131 and the rotor lower cylindrical portion 103b facing it constitute a Holweck type exhaust mechanism 204. The Holweck type exhaust mechanism 204 gives directionality to the exhaust gas by the rotation of the rotor lower cylindrical portion 103b relative to the threaded spacer 131, thereby improving the exhaust characteristics of the turbo molecular pump 100.

[0025] The base portion 129 is a disk-shaped member that constitutes the base of the turbomolecular pump 100, and is generally made of metal such as iron, aluminum, stainless steel, etc. The base portion 129 physically holds the turbomolecular pump 100 and also functions as a heat conduction path, so it is desirable to use a metal that has rigidity and high thermal conductivity, such as iron, aluminum, or copper.

[0026] In this configuration, when the rotor 102 is rotated together with the rotor shaft 113 by the motor 121, the exhaust gas is sucked from the chamber through the intake port 101 by the action of the rotor 102 and the fixed blades 123. The exhaust gas sucked in from the intake port 101 passes between the rotor 102 and the fixed blades 123 and is transferred to the base portion 129. At this time, the temperature of the rotor 102 rises due to frictional heat generated when the exhaust gas comes into contact with the rotor 102 and the conduction of heat generated by the motor 121, and the like, but this heat is transferred to the fixed blades 123 side by radiation or conduction by gas molecules (gas molecules) of the exhaust gas, and the like.

[0027] The fixed blade spacers 125 are joined to each other at their outer peripheries, and transmit heat received by the fixed blades 123 from the rotor blades 102, frictional heat generated when exhaust gas comes into contact with the fixed blades 123, and the like to the outside.

[0028] In the above description, the threaded spacer 131 is disposed on the outer periphery of the rotor lower cylindrical portion 103b of the rotor 103, and the thread groove 131a is engraved on the inner periphery of the threaded spacer 131. However, conversely, there are also cases where a thread groove is engraved on the outer periphery of the rotor lower cylindrical portion 103b, and a spacer having a cylindrical inner periphery is disposed around it.

[0029] Depending on the application of the turbomolecular pump 100, in order to prevent the gas sucked in from the intake port 101 from entering the electrical equipment section consisting of the upper radial electromagnet 104, the upper radial sensor 107, the motor 121, the lower radial electromagnet 105, the lower radial sensor 108, the axial electromagnets 106A and 106B, the axial sensor 109, etc., the electrical equipment section may be surrounded by a stator column 122, and the inside of this stator column 122 may be kept at a predetermined pressure by a purge gas (protective gas).

[0030] In this case, a purge gas introduction pipe (also called a "purge gas port") 13 is provided in the base portion 129, and the purge gas is introduced through this pipe. The introduced purge gas is sent to the exhaust port 133 through gaps (indicated by reference symbol 210 in FIG. 5(a)) between the protective bearing 120 and the rotor shaft 113, between the rotor and stator of the motor 121, between the stator column 122 and the inner cylindrical portion of the rotor 102 (lower cylindrical portion 103b of the rotor) and between the base portion 129.

[0031] Here, the turbomolecular pump 100 requires control based on specific parameters (e.g., various characteristics corresponding to the model) that are individually adjusted and identified as a model. In order to store these control parameters, the turbomolecular pump 100 has an electronic circuit section 141 in its main body. The electronic circuit section 141 is composed of a semiconductor memory such as an EEPROM, electronic components such as semiconductor elements for accessing the memory, and a substrate 143 for mounting these components. The electronic circuit section 141 is housed below a rotational speed sensor (not shown) near the center of a base section 129 that constitutes the lower part of the turbomolecular pump 100, and is closed by an airtight bottom cover 145.

[0032] In the semiconductor manufacturing process, some process gases introduced into the chamber have the property of becoming solid when their pressure exceeds a predetermined value or their temperature falls below a predetermined value. Inside the turbo molecular pump 100, the pressure of the exhaust gas is lowest at the intake port 101 and highest at the exhaust port 133. If the pressure of the process gas becomes higher than a predetermined value or the temperature falls below a predetermined value while the process gas is being transferred from the intake port 101 to the exhaust port 133, the process gas becomes solid and adheres to and accumulates inside the turbo molecular pump 100.

[0033] For example, when SiCl4 is used as the process gas in an Al etching device, low vacuum (760[torr]~10 -2 It can be seen from the vapor pressure curve that at a vapor pressure of 100 MPa (100 [torr]) and low temperature (approximately 20 [°C]), solid products (e.g., AlCl3) precipitate and adhere to and accumulate inside the turbomolecular pump 100. As a result, when precipitates of the process gas accumulate inside the turbomolecular pump 100, the deposits narrow the pump flow path, causing a decrease in the performance of the turbomolecular pump 100. The above-mentioned products are prone to solidification and adhesion in high pressure areas near the exhaust port and near the threaded spacer 131.

[0034] Therefore, in order to solve this problem, conventionally, a heater (not shown) and an annular (ring-shaped) water-cooled pipe 149 are wound around the outer periphery of the base part 129, and a temperature sensor (e.g., a thermistor) (not shown) is embedded in the base part 129, and the heating of the heater and the cooling by the water-cooled pipe 149 are controlled based on a signal from the temperature sensor to keep the temperature of the base part 129 at a constant high temperature (set temperature) (hereinafter referred to as TMS; Temperature Management System). In the turbo molecular pump 100 of the first embodiment, a large amount of hot air (high-temperature fluid, heating fluid) is introduced into the turbo molecular pump 100, and the deposits are heated and vaporized (cleaned). The vaporization of the deposits by hot air will be described later.

[0035] Next, an amplifier circuit 150 that controls excitation of the upper radial electromagnets 104, the lower radial electromagnets 105, and the axial electromagnets 106A and 106B in the turbo molecular pump 100 configured as described above will be described. A circuit diagram of this amplifier circuit is shown in FIG.

[0036] 2, one end of an electromagnet winding 151 constituting the upper radial electromagnet 104 etc. is connected to a positive electrode 171a of a power source 171 via a transistor 161, and the other end is connected to a negative electrode 171b of the power source 171 via a current detection circuit 181 and a transistor 162. The transistors 161 and 162 are so-called power MOSFETs, and have a structure in which a diode is connected between the source and drain.

[0037] At this time, the transistor 161 has a cathode terminal 161a of the diode connected to the positive electrode 171a, and an anode terminal 161b connected to one end of the electromagnet winding 151. The transistor 162 has a cathode terminal 162a of the diode connected to the current detection circuit 181, and an anode terminal 162b connected to the negative electrode 171b.

[0038] On the other hand, the current regeneration diode 165 has its cathode terminal 165a connected to one end of the electromagnet winding 151 and its anode terminal 165b connected to the negative electrode 171b. Similarly, the current regeneration diode 166 has its cathode terminal 166a connected to the positive electrode 171a and its anode terminal 166b connected to the other end of the electromagnet winding 151 via a current detection circuit 181. The current detection circuit 181 is composed of, for example, a Hall sensor type current sensor or an electric resistance element.

[0039] The amplifier circuit 150 configured as above corresponds to one electromagnet. Therefore, when the magnetic bearing is controlled by five axes and there are a total of ten electromagnets 104, 105, 106A, and 106B, a similar amplifier circuit 150 is configured for each electromagnet, and the ten amplifier circuits 150 are connected in parallel to the power supply 171.

[0040] Furthermore, the amplifier control circuit 191 is configured, for example, by a digital signal processor section (hereinafter referred to as a DSP section) (not shown) of the control device 200, and this amplifier control circuit 191 switches the transistors 161 and 162 on / off.

[0041] The amplifier control circuit 191 is adapted to compare the current value detected by the current detection circuit 181 (a signal reflecting this current value is called a current detection signal 191c) with a predetermined current command value. Then, based on the result of this comparison, the magnitude of the pulse width (pulse width times Tp1, Tp2) to be generated within a control cycle Ts, which is one period of PWM control, is determined. As a result, gate drive signals 191a, 191b having this pulse width are output from the amplifier control circuit 191 to the gate terminals of the transistors 161, 162.

[0042] It is necessary to control the position of the rotor 103 at high speed and with strong force when, for example, the rotor 103 passes through a resonance point during an accelerating operation of the rotation speed, or when a disturbance occurs during a constant speed operation. For this reason, a high voltage of, for example, about 50 V is used as the power supply 171 so that the current flowing through the electromagnet winding 151 can be rapidly increased (or decreased). In addition, a capacitor (not shown) is usually connected between the positive pole 171a and the negative pole 171b of the power supply 171 to stabilize the power supply 171.

[0043] In this configuration, when both transistors 161, 162 are turned on, the current flowing through the electromagnet winding 151 (hereinafter referred to as electromagnet current iL) increases, and when both are turned off, the electromagnet current iL decreases.

[0044] Moreover, when one of the transistors 161, 162 is turned on and the other is turned off, a so-called flywheel current is maintained. By passing a flywheel current through the amplifier circuit 150 in this manner, the hysteresis loss in the amplifier circuit 150 can be reduced, and the power consumption of the entire circuit can be kept low. Furthermore, by controlling the transistors 161, 162 in this manner, high-frequency noise such as harmonics generated in the turbo molecular pump 100 can be reduced. Furthermore, by measuring this flywheel current with the current detection circuit 181, the electromagnet current iL flowing through the electromagnet winding 151 can be detected.

[0045] That is, when the detected current value is smaller than the current command value, both of the transistors 161 and 162 are turned on for a time period corresponding to the pulse width time Tp1 only once in a control cycle Ts (e.g., 100 μs) as shown in Fig. 3. Therefore, the electromagnet current iL during this period increases toward a current value iLmax (not shown) that can flow from the positive electrode 171a to the negative electrode 171b via the transistors 161 and 162.

[0046] On the other hand, when the detected current value is larger than the current command value, both of the transistors 161 and 162 are turned off for a time period corresponding to the pulse width time Tp2 only once during the control cycle Ts, as shown in Fig. 4. Therefore, the electromagnet current iL during this period decreases toward a current value iLmin (not shown) that can be regenerated from the negative pole 171b to the positive pole 171a via the diodes 165 and 166.

[0047] In either case, after the pulse width times Tp1 and Tp2 have elapsed, one of the transistors 161 and 162 is turned on. Therefore, a flywheel current is maintained in the amplifier circuit 150 during this period.

[0048] 1 (the side of the intake port 101) of the turbomolecular pump 100 having such a basic configuration is an intake section connected to the target device, and the lower side (the side where the exhaust port 15 constituting the exhaust port 133 is provided on the base part 129 so as to protrude to the right side in the figure) is an exhaust section connected to an auxiliary pump (not shown) (a dry pump 16 to be described later, also called a "back pump"), etc. The turbomolecular pump 100 can be used in an inverted, horizontal or inclined position in addition to the vertical position shown in FIG.

[0049] In the turbomolecular pump 100, the outer cylinder 127 and the base portion 129 are combined to form one case (hereinafter, both may be collectively referred to as the "main casing"). The turbomolecular pump 100 is electrically (and structurally) connected to a box-shaped electrical equipment case (not shown), and the above-mentioned control device 200 is incorporated in the electrical equipment case.

[0050] The internal configuration of the main body casing of the turbomolecular pump 100 (a combination of an outer cylinder 127 and a base portion 129) can be divided into a rotation mechanism portion that rotates the rotor shaft 113 and the like by the motor 121, and an exhaust mechanism portion that is rotationally driven by the rotation mechanism portion. The exhaust mechanism portion can be considered to be divided into a turbomolecular pump mechanism portion composed of the rotor 102, fixed blades 123, etc., and a threaded pump mechanism portion (Holbeck type exhaust mechanism portion 204) composed of the rotor lower cylindrical portion 103b, threaded spacer 131, etc.

[0051] The above-mentioned purge gas (protective gas) is used to protect the bearing parts and the rotor 102, etc., to prevent corrosion caused by the exhaust gas (process gas), and to cool the rotor 102. This purge gas can be supplied by a general method.

[0052] For example, a purge gas port 13 extending linearly in the radial direction is provided at a predetermined position (such as a position approximately 180 degrees away from the exhaust port 133) of the base portion 129. Then, purge gas is supplied to this purge gas port 13 from the outside of the base portion 129 via a purge gas cylinder (such as an N2 gas cylinder) or a flow rate regulator (valve device).

[0053] The aforementioned protective bearings 120 are also called "touch-down (T / D) bearings" or "back-up bearings." These protective bearings 120 prevent the position and attitude of the rotor shaft 113 from changing significantly, and prevent damage to the rotor blades 102 and their surroundings, even in the unlikely event that a problem occurs with the electrical system or atmospheric inrush.

[0054] In FIG. 1 showing the structures of the turbo molecular pump 100 and the rotor 103, hatching showing cross sections of components is omitted to avoid complicating the drawing.

[0055] <Vacuum Exhaust System 10> <<Basic configuration of the vacuum exhaust system 10>> Fig. 5(a) shows a vacuum exhaust system 10 according to an embodiment of the present invention. The vacuum exhaust system 10 is equipped with a plurality of turbo molecular pumps 100. In the following description, the plurality of (here, n) turbo molecular pumps 100 are appropriately designated by the reference characters "100-1" to "100-n", where "n" denotes an integer of 2 or more. The same applies to "n" of chambers 12-1 to 12-n described below.

[0056] A dry pump 16 is connected to each of the turbo molecular pumps 100-1 to 100-n via a collecting pipe 14. The dry pump 16 has a function of maintaining the back pressure of the turbo molecular pumps 100-1 to 100-n. A positive displacement vacuum pump or the like can be used as the dry pump 16. The collecting pipe 14 will be described later.

[0057] The vacuum exhaust system 10 is used to exhaust gas (such as process gas) from a plurality of chambers (processing chambers) 12-1 to 12-n of a manufacturing apparatus for semiconductors (semiconductors, flat panels, etc.). Turbo molecular pumps 100-1 to 100-n are connected to the individual chambers 12-1 to 12-n.

[0058] For example, although not shown, a transfer chamber and a load lock chamber can be provided around the chambers 12-1 to 12-n. A rough vacuum pump is connected to the transfer chamber and the load lock chamber, and a vacuum is formed in the transfer chamber and the load lock chamber. The load lock chamber enables the transfer of semiconductors and the like between the vacuum space in the transfer chamber and an atmospheric pressure region while maintaining the vacuum in the transfer chamber. A transfer robot is disposed in the transfer chamber, and the transfer robot transfers the semiconductors and the like to one of the chambers 12-1 to 12-n. A process gas and the like is supplied to each of the chambers 12-1 to 12-n.

[0059] In the example of FIG. 5(a), turbo molecular pumps 100-1 to 100-n are connected to the individual chambers 12-1 to 12-n, respectively. However, for example, multiple turbo molecular pumps may be connected to one chamber. Also, one turbo molecular pump may be connected to multiple chambers. In these cases, the "n" of the chambers 12-1 to 12-n does not match the "n" of the turbo molecular pumps 100-1 to 100-n.

[0060] Furthermore, when multiple turbomolecular pumps are connected to one chamber, it becomes possible, for example, to use multiple turbomolecular pumps simultaneously, or to switch to another turbomolecular pump if one turbomolecular pump breaks down.

[0061] Furthermore, although turbomolecular pump 100 is shown here as an example of a usable turbomolecular pump, turbomolecular pumps 100-1 to 100-n may all be turbomolecular pumps of the same configuration, or some or all of them may be turbomolecular pumps of different configurations.

[0062] In this embodiment, as described below, the vacuum exhaust system 10 also has a function of controlling the introduction of gas into the chambers 12-1 to 12-n. However, the function of controlling the introduction of gas into the chambers 12-1 to 12-n may be provided in another device or system (e.g., a process control system). Furthermore, the vacuum exhaust system 10 and the other device or system may be collectively referred to as, for example, a "system" or an "overall system."

[0063] <<Features of the centralized exhaust type>> Fig. 5(a) shows a centralized exhaust type vacuum exhaust system 10. Generally, a distributed exhaust type vacuum exhaust system 50 as shown in Fig. 5(b) is widely used, but the vacuum exhaust system 10 according to this embodiment is of the centralized exhaust type. Such a centralized exhaust type vacuum exhaust system 10 has advantages in terms of cost, energy consumption, installation space, etc., compared to the distributed exhaust type vacuum exhaust system 50 shown in Fig. 5(b), for example.

[0064] 5(b), dry pumps 16-1 to 16-n are connected to the turbo molecular pumps 100-1 to 100-n, respectively. Therefore, the number of dry pumps 16-1 to 16-n is large, and the cost is accordingly high.

[0065] In addition, dry pumps (such as the dry pumps 16-1 to 16-n) usually consume a lot of energy, such as electricity, and providing a large number of dry pumps 16-1 to 16-n increases the energy consumption accordingly. Furthermore, installing a large number of dry pumps 16-1 to 16-n requires a large installation space.

[0066] In view of these circumstances, in a centralized exhaust type vacuum exhaust system 10 as shown in FIG. 5(a), one dry pump 16 is connected to a plurality of turbo molecular pumps 100-1 to 100-n via a collecting pipe 14 as described above.

[0067] The collecting pipe 14 is a pipe having a shape that branches into multiple parts, and the multiple branched pipe sections (piping sections on the branched side) are connected to exhaust ports (exhaust port 15 in the example of FIG. 1) of the turbo molecular pumps 100-1 to 100-n. The pipe section on the collected side of the collecting pipe 14 is connected to an intake port (not shown) of the dry pump 16.

[0068] Hereinafter, the piping section on the branched side of the collecting pipe 14 will be referred to as a "branching pipe section" and will be given the reference numerals 14-1 to 14-n. Also, the piping section on the collected side of the collecting pipe 14 will be referred to as a "collecting pipe section" and will be given the reference numeral 18. Note that the "n" in the branching pipe sections 14-1 to 14-n of the collecting pipe 14 may not necessarily match the "n" in the turbo molecular pumps 100-1 to 100-n. Also, the collecting pipe 14 may be a combination of multiple collecting pipes, or may be used in combination with a single pipe.

[0069] In this way, in the centralized exhaust type vacuum pumping system 10, one dry pump 16 is assigned to the multiple turbo molecular pumps 100-1 to 100-n, and the number of dry pumps 16 is smaller than in the distributed type vacuum pumping system 50 (FIG. 5(b)). This makes it possible to reduce the cost required for the dry pumps 16. In addition, the energy consumption and installation space required for the dry pumps 16 are also small.

[0070] However, the centralized exhaust type vacuum pumping system 10 also has some problems if the device as in this embodiment (described later) is not implemented. For example, to fully ensure exhaust related to the multiple chambers 12-1 to 12-n and turbo molecular pumps 100-1 to 100-n and exhaust through long flow paths (pipes), it is necessary to use a large (high-speed, high-exhaust speed) dry pump 16 compared to the individual dry pumps 16-1 to 16-n of the decentralized vacuum pumping system 50 (FIG. 5(b)).

[0071] In addition, the turbo molecular pumps 100-1 to 100-n must be of a type that can maintain the intake pressure even if the back pressure is relatively high and has excellent back pressure dependency. Furthermore, since the collecting pipe 14 must be used, the degree of freedom in piping design is lower than that of the distributed vacuum pumping system 50 (FIG. 5(b)).

[0072] In addition, when the inventors first developed the centralized exhaust type vacuum exhaust system 10, they assumed and designed the back pressure of the turbo molecular pumps 100-1 to 100-n to be the back pressure (turbo back pressure) when the flow rates of all the systems were simultaneously at their maximum. However, when the exhaust rates of the individual turbo molecular pumps 100-1 to 100-n in the actual process were measured, it was found that there were only a few cases where the maximum flow rate (Qmax, for example, 3000 sccm) of a certain turbo molecular pump was exceeded, as shown in the graph of FIG.

[0073] Here, the horizontal axis of FIG. 6 indicates time, and the vertical axis indicates the displacement (flow rate at each moment during operation) of a certain turbomolecular pump. In the example of FIG. 6, the displacement increases stepwise with the passage of time, reaches a maximum value (Qmax of a certain turbomolecular pump) in the middle, and then decreases stepwise. The time period during which the maximum value is shown is a part of the entire operation period, and during other time periods, operation is performed at a displacement rate lower than the maximum value (Qmax). Note that the change in flow rate as shown in FIG. 6 occurs in other turbomolecular pumps, and the sum of the flow rates at a certain point in time is the total flow rate at that point in time. The content of the change in flow rate is usually different for multiple turbomolecular pumps. However, the content of the change in flow rate may be common to some of the multiple turbomolecular pumps.

[0074] Based on this knowledge, the inventors have come up with the idea of ​​controlling the total flow rate of gas flowing through the chambers 12-1 to 12-n connected to the vacuum exhaust system 10. The inventors have then made it possible to design the vacuum exhaust system 10 without pursuing an excessively low back pressure for the turbo molecular pumps 100-1 to 100-n.

[0075] <<Basic Concepts for Adjusting Total Flow Rate and Exhaust Flow Rate Thresholds>> Specifically, for example, the vacuum pumping system 10 can be controlled and operated based on the following concepts in the order of (1) to (3).

[0076] (1) The start timing of the process is adjusted so that the total flow rate (Q=Q1+Q2+Q3+···+Qn, the total introduction amount which is the sum of the amounts of gas introduced into the individual chambers) related to the turbo molecular pumps 100-1 to 100-n does not exceed a threshold (exhaust flow rate threshold). Here, Q1 to Qn are the flow rates (total flow rate, total flow rate, total introduction amount, total introduction amount) at each of the turbo molecular pumps 100-1 to 100-n at that time.

[0077] Usually, a process follows a time chart (process time chart) that is prepared in advance. By referring to the time chart, it is possible to know, for example, what value the total flow rate (total flow rate at a certain point in time) will be after how many seconds. For this reason, the total flow rate that is expected when a process is started in each of chambers 12-1 to 12-n is calculated, and the timing of the start of the process is controlled sufficiently before the total flow rate exceeds a threshold value so that the total flow rate does not exceed the threshold value. In this way, the total flow rate at that point in time can be kept low, and it is possible to delay the time when the total flow rate reaches the threshold value.

[0078] The threshold value can be determined based on the maximum total flow rate at a certain moment in the entire system assumed when designing the vacuum exhaust system 10. It can also be set as the maximum flow rate per chamber x number of chambers x coefficient (safety factor < 1) or the average flow rate per chamber x number of chambers x coefficient (safety factor ≥ 1). When starting a process in each of the chambers 12-1 to 12-n, it is possible to start the process at a timing that does not cause the expected total flow rate to exceed the threshold value based on the above-mentioned threshold value.

[0079] (2) Furthermore, the threshold value of the total flow rate is changed. In other words, the vacuum performance of a chamber is generally affected by turbo deterioration and foreline deterioration. Here, the "foreline" is the piping that connects the turbo molecular pumps 100-1 to 100-n to the dry pump 16. In the example of FIG. 5(a), the collecting pipe 14 constitutes the foreline.

[0080] Turbo deterioration occurs due to the blockage of the gas flow path caused by deposits. Foreline deterioration occurs due to blockage of the piping caused by deposits, deterioration of dry performance (performance of the dry pump), etc. Therefore, the total flow rate threshold is changed according to the degree of such deterioration.

[0081] In this embodiment, the threshold is lowered as deterioration progresses, but the threshold can be raised if, for example, vacuum performance is restored through so-called conservation activities such as removing deposits by cleaning.

[0082] Also, for example, a to e are used as information for evaluating the degree of deterioration. a. An increase in pressure (intake pressure, exhaust port pressure, screw inlet pressure, etc.) within the turbomolecular pump (here, turbomolecular pumps 100-1 to 100-n). b. An increase in the motor current (here, the value of the current flowing through the motor 121). c. An increase in the output of the deposit sensor due to the occurrence or increase of deposits. d. APC (Automatic Pressure Control) valve opening provided at the intake port (intake port 101 in this case) of a turbomolecular pump (turbomolecular pumps 100-1 to 100-n in this case). e. Pressure build-up in the foreline piping.

[0083] (3) The timing of maintenance is determined based on the change in the total flow rate threshold over time, and this is used for preventive and predictive maintenance.

[0084] <<Specific examples of total flow rate adjustments>> Based on this concept, as described above, the vacuum exhaust system 10 according to this embodiment is equipped with the turbo molecular pumps 100-1 to 100-n, the collecting pipe 14, and the dry pump 16. The vacuum exhaust system 10 further includes an exhaust system control unit 20. As shown in FIG. 7, the exhaust system control unit 20 includes a central processing unit (CPU) 22, a storage unit 24, an input / output unit 26, and the like.

[0085] The exhaust system control unit 20 has various functions for controlling the vacuum exhaust system 10. The functions of the exhaust system control unit 20 include a function to control the timing of introducing gas into the chambers 12-1 to 12-n so that the total flow rate (Q=Q1+Q2+Q3+···+Qn, total total flow rate) related to the turbo molecular pumps 100-1 to 100-n does not exceed a predetermined threshold (exhaust flow rate threshold). The functions of the exhaust system control unit 20 can also include a function to control the flow rate of gas into the chambers 12-1 to 12-n.

[0086] Here, Q1 to Qn are the flow rates (total flow rate, total flow rate, total introduced amount, total introduced amount) at each of the turbo molecular pumps 100-1 to 100-n at that time, as described above.

[0087] It is also possible to provide both a function for controlling the gas introduction timing and a function for controlling the flow rate, and to use only one of these functions.It is also possible to control the flow rate after controlling the gas introduction timing (using both functions in combination).

[0088] The timing of gas introduction can be controlled by controlling the gas inlets of chambers 12-1 to 12-n and the valve devices (here, chamber introduction valve devices 30-1 to 30-n) upstream of the gas inlets. In this case, the state of chamber introduction valve devices 30-1 to 30-n into which gas should be introduced among chambers 12-1 to 12-n is changed from a closed state to an open state to allow the inflow of gas.

[0089] Moreover, the exhaust system control unit 20 can control the flow rate of gas into the chambers 12-1 to 12-n by adjusting the opening of the chamber introduction valve device.

[0090] As described above, in the chambers 12-1 to 12-n, processes are performed according to a time chart (not shown) prepared in advance. By utilizing the timing information defined in this time chart, the operation timing of each of the chamber introduction valve devices 30-1 to 30-n and the gas flow rate information of each of the turbo molecular pumps 100-1 to 100-n can be known (determined) in advance.

[0091] In the exhaust system control unit 20, for example, by summing up the total flow rates (Q1, Q2, Q3, ..., Qn) of gas introduced into each of the chambers 12-1 to 12-n during a period from when gas introduction into some (or all) of the chambers 12-1 to 12-n begins until a certain time, a theoretical value of the total gas flow rate (Q = Q1 + Q2 + Q3 + ... + Qn) at that time is calculated. The total gas flow rate usually increases with the passage of time. Note that, in this description, the gas flow rate of the turbo molecular pumps 100-1 to 100-n is assumed to be equal to the gas flow rate related to the chambers 12-1 to 12-n.

[0092] A predetermined exhaust flow rate threshold value T is stored in the memory unit 24 of the exhaust system control unit 20. For example, when the vacuum exhaust system 10 starts to operate (starts to be used), no deposits are formed and the vacuum exhaust system 10 is in a clean state. In such a case, the exhaust flow rate threshold value T is set to an initial value T0. The initial value T0 of the exhaust flow rate threshold value T can be set to a value that the total flow rate Q can reach at a certain point in time.

[0093] The exhaust system control unit 20 determines when the value of the total flow rate Q calculated based on the time chart will reach the exhaust flow rate threshold T. The exhaust system control unit 20 selects a chamber (one or more of the chambers 12-1 to 12-n) that is expected to have a relatively large gas flow rate when the value of the total flow rate Q reaches the exhaust flow rate threshold T. Furthermore, the exhaust system control unit 20 changes the opening timing and / or the opening degree control of the chamber introduction valve devices 30-1 to 30-n corresponding to the selected chamber from the scheduled control mode.

[0094] More specifically, the exhaust system control unit 20 delays the opening timing and / or maintains (or reduces) the opening degree of the targeted chamber introduction valve device 30-1 to 30-n. After that (for example, after several seconds to several tens of seconds), the targeted chamber introduction valve device 30-1 to 30-n is controlled at the scheduled opening timing and / or opening degree, and the control related to the gas introduction is returned to the scheduled state.

[0095] In this way, the exhaust system control unit 20 delays (delays) the timing of introducing or increasing the gas into the selected chamber to suppress an increase in the total flow rate Q. The exhaust system control unit 20 then introduces or increases the gas into the selected chamber to supply the planned amount of gas to the selected chamber. Even in this case, the exhaust system control unit 20 controls the supply of gas so that Q≧T does not occur.

[0096] Here, what is virtually indicated in Fig. 5(a) by reference numerals 32 and 33 are the control target ranges of the exhaust system control unit 20. In the example of Fig. 5(a), one control target range 32 of the exhaust system control unit 20 includes turbo molecular pumps 100-1 to 100-n and dry pump 16. Moreover, the other control target range 33 of the exhaust system control unit 20 includes chamber introduction valve devices 30-1 to 30-n.

[0097] In the example of Figure 5(a), the exhaust system control unit 20 and the control ranges 32, 33 are connected by a dotted line, which roughly shows that electrical (or electronic) signals (information expressed electrically (or electronically)) are sent and received between the exhaust system control unit 20 and each device (including those not shown) within the control ranges 32, 33.

[0098] The above-mentioned "system" and "whole system" include these controlled ranges 32, 33 as well as peripheral devices and systems. For example, it is possible to set only a portion of the devices including the turbo molecular pumps 100-1 to 100-n (or only the turbo molecular pumps 100-1 to 100-n) as the direct controlled range of the exhaust system control unit 20 (constituent devices of the vacuum exhaust system 10), and to set the other devices as devices controlled by another control system.

[0099] It is not necessarily required that the exhaust system control unit 20 directly controls the supply of gas to the chambers 12-1 to 12-n (the opening / closing and the opening degree of the chamber introduction valve devices 30-1 to 30-n, etc.). For example, the exhaust system control unit 20 may be configured to issue an alarm (warning, notification) to the outside of the vacuum exhaust system 10 when the total flow rate Q exceeds the exhaust flow rate threshold T.

[0100] The "alarm" mentioned here may be an electrical (or electronic) signal (information). For example, based on the output alarm, the control unit (process control unit, not shown in the figure) of the process control system can suppress the gas supply to chambers 12-1 to 12-n, for example, so that the total flow rate Q does not exceed the exhaust flow rate threshold value T.

[0101] Also, it is possible to output the "alarm" to notification devices (alarm devices) such as a display device (not shown in the figure) like a liquid crystal or a speaker (not shown in the figure). In this case, the operator who perceives the content displayed on the display device (display content) and the sound emitted from the speaker (not shown in the figure) can adjust the gas supply to chambers 12-1 to 12-n or input an instruction to the device for adjusting the gas supply.

[0102] <<Specific example regarding adjustment of exhaust flow rate threshold value T>> When starting the operation of the vacuum exhaust system 10 and continuously exhausting the gas related to chambers 12-1 to 12-n, usually, deposits are generated and the deterioration of the vacuum exhaust system 10 progresses. The exhaust system control unit 20 determines the degree of deterioration of the vacuum exhaust system 10 and adjusts the exhaust flow rate threshold value T according to the degree of deterioration.

[0103] When the deterioration progresses to a predetermined level, the exhaust system control unit 20 lowers the exhaust flow rate threshold value T from the initial value T0 to T1 which is lower than T0. Also, as the deterioration further progresses, the exhaust flow rate threshold value T is lowered from T1 to T2 (<T1). Such adjustment of the exhaust flow rate threshold value T can be lowered step by step to T2, T3, T4,... (T2>T3>T4...) according to the degree of deterioration.

[0104] <<An example of evaluation index (pressure)>> For the adjustment of the exhaust flow rate threshold value T, information for evaluating the degree of deterioration of the vacuum exhaust system 10 (evaluation index of the degree of deterioration) is used. As the evaluation index, it is possible to use various parameters indicating the state of the vacuum exhaust.

[0105] For example, the pressure inside the turbo molecular pumps 100-1 to 100-n can be used as an evaluation index. This corresponds to "a." among the above-mentioned "a." to "e." In this case, at least one pressure among the intake pressure, exhaust port pressure, screw inlet pressure, etc. in the turbo molecular pumps 100-1 to 100-n is detected.

[0106] Although not shown, in the case of the turbo molecular pump 100 illustrated in Fig. 1, for example, pressure can be detected by installing a pressure sensor on the inner wall of the intake port 101 or exhaust port 15, or on the wall surface facing the gas inlet (screw inlet) of the thread groove pump mechanism (Holbeck type exhaust mechanism 204). Various types of pressure sensors, including general types, can be used. It is also possible to detect pressures other than the intake pressure, exhaust port pressure, and screw inlet pressure.

[0107] The exhaust system control unit 20 calculates the pressure (actual measurement value) based on the output signal of the pressure sensor. The exhaust system control unit 20 stores a reference pressure value (pressure reference value). The pressure reference value can be determined, for example, by using the pressure value (design value, theoretical value) at the time when the turbo molecular pump 100 starts to operate (start to be used). It is also possible to store a table of the relationship between a plurality of operating conditions and a plurality of pressure reference values ​​corresponding to the conditions.

[0108] In the exhaust system control unit 20, the calculated pressure is compared with the pressure at the start of operation (start of use) of the turbo molecular pump 100. If it is determined that the actual pressure measurement value (pressure measurement value) has increased by a predetermined value (or a predetermined ratio) or more with respect to the pressure reference value, the exhaust system control unit 20 determines that the deterioration has progressed beyond the allowable range, and lowers the exhaust flow rate threshold T from T0 to T1.

[0109] The newly set exhaust flow rate threshold T1 is used to adjust the above-mentioned total flow rate Q. For example, the exhaust system control unit 20 performs control to delay the opening timing of the chamber introduction valve devices 30-1 to 30-n and / or maintain (or reduce) the opening degree so that the total flow rate Q determined based on the time chart does not exceed the new exhaust flow rate threshold T1.

[0110] <<Another example of evaluation index (motor current)>> It is also possible to use an increase in the value of the current (motor current) flowing through the motor 121 as an evaluation index for the degree of deterioration. This corresponds to "b." among the above-mentioned ideas "a." to "e." When deterioration of the vacuum exhaust system 10 progresses, the value of the motor current becomes larger in the turbo molecular pump 100 in order to obtain the target gas flow rate and rotation speed, compared to when deterioration does not progress. For this reason, it is possible to determine the degree of deterioration by monitoring the motor current.

[0111] In this case, the relationship between the degree of deterioration and the change in motor current is stored in a table, and the exhaust system control unit 20 can determine the degree of deterioration of the detected motor current by referring to the table. When the motor current reaches a predetermined value, the exhaust system control unit 20 determines that the deterioration has progressed to a predetermined degree, and lowers the exhaust flow rate threshold T to T1. Note that the motor current can be determined using, for example, the detection results of the electromagnet current iL flowing through the electromagnet winding 151 (FIG. 2) described above or other currents.

[0112] <<Another example of an evaluation index (amount of sediment)>> It is also possible to use the increase in output of a deposit sensor (deposit sensor) that accompanies the generation or increase of deposits as an evaluation index of the degree of deterioration. This corresponds to "c." among the above-mentioned "a." to "e." concepts.

[0113] The deposit sensor can be installed, for example, at a location in the turbo molecular pump 100 (FIG. 1) where deposits are likely to occur. More specifically, a location downstream of the exhaust gas (process gas) in the turbo molecular pump 100 can be mentioned. Even more specifically, a location on the inner bottom of the base portion 129 facing the Holweck type exhaust mechanism portion 204 and the lower cylindrical portion 103b of the rotor can be mentioned. The deposit sensor can also be located at a location closer to the exhaust port 133.

[0114] <<Another example of an evaluation index (APC valve opening)>> In addition, the valve openings (APC valve opening, valve body opening, valve body opening) of the APC (Automatic Pressure Control) valve devices 40-1 to 40-n can be used as an evaluation index of the deterioration degree. This corresponds to "d." among the above-mentioned "a." to "e." concepts.

[0115] As shown in FIG. 5(a), the APC valve devices 40-1 to 40-n are installed so as to be connected to the intake ports (intake port 101) of the respective turbo molecular pumps 100-1 to 100-n, and control the flow rates of gas flowing into the respective turbo molecular pumps 100-1 to 100-n.

[0116] When the amount of deposits increases in any one of the turbo molecular pumps 100-1 to 100-n and the gas flow rate decreases, the corresponding APC valve device among the APC valve devices 40-1 to 40-n is automatically controlled to increase the opening so that the gas flow rate to the corresponding turbo molecular pump increases and the gas flow rate is maintained. The gas flow rate decrease can be determined based on the average opening of the multiple APC valve devices or when the opening of a specific (for example, one) APC valve device increases above a scheduled value.

[0117] In this way, the APC valve opening changes in response to a change (decrease) in the flow rate of the gas in the turbo molecular pumps 100-1 to 100-n. Therefore, for example, the exhaust system control unit 20 can monitor the APC valve opening and determine the degree of deterioration according to the APC valve opening.

[0118] <<An example of an evaluation index (foreline pressure rise)>> In addition, the pressure rise in the foreline piping can be used as an evaluation index of the degree of deterioration. This corresponds to "e." among the above-mentioned "a." to "e." In the example of Fig. 5(a), the branch pipe sections 14-1 to 14-n in the collecting pipe 14 and the collecting pipe section 18 can be used as the foreline.

[0119] In the example of Fig. 5(a), pressure gauges 44-1 to 44-n, 48 are installed in the branch pipe sections 14-1 to 14-n and the collecting pipe section 18. The pressure gauges 44-1 to 44-n change the value of the output signal according to the pressure of the gas flowing through the branch pipe sections 14-1 to 14-n and the collecting pipe section 18. Although not shown in the figure, the output signals of the pressure gauges 44-1 to 44-n, 38 are input to the exhaust system control section 20. The exhaust system control section 20 compares the detected pressure with a normal pressure stored in advance, and when the pressure rises above a reference value (pressure threshold), for example, the exhaust system control section 20 issues an alarm (alarm, report) to the outside informing of an abnormality in the vacuum exhaust system 10 or for maintenance.

[0120] <<Maintenance alarm>> The exhaust system control unit 20 issues an alarm to the outside when the amount of decrease in the adjusted exhaust flow rate threshold T reaches a predetermined amount. Specifically, the exhaust system control unit 20 determines whether the exhaust flow rate threshold T has decreased to a predetermined value or less, and issues an alarm (warning, notification) to the outside of the vacuum exhaust system 10 when the exhaust flow rate threshold T has decreased to the predetermined value or less.

[0121] The "alarm" here may be an electrical (or electronic) signal (information). For example, a cleaning device (e.g., a plasma cleaning device, not shown) may be connected to the turbo molecular pump 100, and based on the output of an alarm, the normal operation of the turbo molecular pump 100 may be stopped and the cleaning device may be operated.

[0122] Also, the "alarm" can be output to a notification device (alarm device) such as the above-mentioned liquid crystal display device or speaker. In this case, an operator who perceives the displayed content or sound can operate a cleaning device connected to the turbomolecular pumps 100-1 to 100n, or remove the turbomolecular pumps 100-1 to 100n from the vacuum exhaust system 10 to clean the turbomolecular pumps 100-1 to 100n.

[0123] <Advantages of the invention according to the embodiment> According to the vacuum pumping system 10 of the present embodiment as described above, at least one of the gas introduction timing and flow rate is controlled by the gas introduction rate control means so that the total flow rate Q of the turbo molecular pumps 100-1 to 100-n does not exceed the exhaust flow rate threshold T. Therefore, it is possible to keep the total flow rate at that point low. Also, it is possible to delay the time when the total flow rate reaches the threshold.

[0124] For these reasons, it is no longer necessary to increase the size of the dry pump 16, to use piping with a small conductance, or to adopt a turbo molecular pump with excellent back pressure dependency. It is then possible to provide a vacuum exhaust system 10 that allows for cost reduction and size reduction of the exhaust system, and / or improved freedom in piping design, and vacuum pumps (turbo molecular pumps 100-1 to 100-n) that can be used in the vacuum exhaust system.

[0125] Furthermore, according to the vacuum exhaust system 10 of this embodiment, the exhaust flow rate threshold T is adjusted based on signals relating to the following conditions. a. An increase in pressure (intake pressure, exhaust port pressure, screw inlet pressure, etc.) within the turbomolecular pump (here, turbomolecular pumps 100-1 to 100-n). b. An increase in the motor current (here, the value of the current flowing through the motor 121). c. An increase in the output of the deposit sensor due to the occurrence or increase of deposits. d. APC (Automatic Pressure Control) valve opening provided at the intake port (intake port 101 in this case) of a turbomolecular pump (turbomolecular pumps 100-1 to 100-n in this case). e. Pressure build-up in the foreline piping. Therefore, the exhaust flow rate threshold T can be adjusted based on the detection of the degree of deterioration in the vacuum exhaust system 10 and each location in the vicinity thereof. Then, the exhaust flow rate threshold T can be appropriately set each time according to the degree of deterioration.

[0126] The above-mentioned "a." to "c." can be considered to be items (also called "parameters") that indicate the degree of deterioration in the turbo molecular pumps 100-1 to 100-n. The above-mentioned "d." to "e." can be considered to be items that indicate the degree of deterioration outside the turbo molecular pumps 100-1 to 100-n.

[0127] Additionally, "a." to "c." can be said to be items related to detection performed by the vacuum exhaust system 10. The above-mentioned "d." to "e." can also be included in items related to detection performed by the vacuum exhaust system 10, or can be included in items related to detection performed outside the vacuum exhaust system 10.

[0128] Furthermore, according to the vacuum exhaust system 10 of this embodiment, when the total flow rate Q exceeds the exhaust flow rate threshold T (or when it is determined that the total flow rate Q will exceed the exhaust flow rate threshold T), an alarm is issued to the outside. This "alarm" is a concept that includes the transmission of electrical (or electronic) signals and information. Therefore, it becomes possible to take measures based on this "alarm." The measures include various operations and controls (including those performed manually and automatically) to prevent the total flow rate Q from actually exceeding the exhaust flow rate threshold T.

[0129] Furthermore, according to the vacuum exhaust system 10 of this embodiment, the exhaust flow rate threshold T is adjusted sequentially, and the exhaust flow rate threshold T changes over time (changes in a time series). Then, when the amount of decrease in the exhaust flow rate threshold T (T-T1, T1-T2, T2-T3, . . ., T-T2, T-T3, . . . etc.) reaches a predetermined amount, an alarm is issued to the outside. This "alarm" is also a concept that includes the transmission of electrical (or electronic) signals and information. Therefore, it becomes possible to take measures based on this "alarm."

[0130] The countermeasures include maintenance activities such as removing the causes of the deterioration. The countermeasures also include determining the timing of maintenance, preventing deterioration, and identifying signs of deterioration. Furthermore, if the countermeasures have restored the vacuum performance, it is possible to raise the exhaust flow rate threshold T (for example, to return it to its original value).

[0131] It is possible to provide a gas introduction amount acquiring means for acquiring the amount of gas introduction. Acquiring the amount of gas introduction includes acquiring a signal indicating the amount of gas introduction, acquiring a signal (information) indicating a change in the amount of gas introduction under certain conditions, and the like.

[0132] The gas introduction amount acquisition means includes a means (gas introduction amount sensor) for detecting the amount of gas flowing into, passing through, and / or flowing out of chambers 12-1 to 12-n, and a means for calculating or acquiring information on the total flow rate (individual introduction amounts, total introduction amount obtained by adding up the individual introduction amounts, etc.) from information on the detected gas flow rates (detection results). For example, exhaust system control unit 20 can be used as a means for calculating or acquiring information on various introduction amounts.

[0133] Moreover, the turbo molecular pumps 100-1 to 100-n used in the vacuum exhaust system 10 as described above contribute to the construction of the vacuum exhaust system 10.

[0134] <Inventions that can be extracted from the embodiments> (1) A vacuum exhaust system (such as vacuum exhaust system 10) for exhausting a processing gas (such as a process gas) from a plurality of processing chambers (such as chambers 12-1 to 12-n), The vacuum pumping system includes: A plurality of first vacuum pumps (turbo molecular pumps 100-1 to 100-n, etc.); a collector pipe (such as the collector pipe 14) that connects exhaust ports (such as the exhaust port 133) of the plurality of first vacuum pumps in parallel; One or more second vacuum pumps (such as a dry pump 16) connected to the collecting pipe; a gas introduction amount control unit (such as an exhaust system control unit 20, chamber introduction valve devices 30-1 to 30-n) for controlling a flow rate (such as a gas amount per unit time) of gas introduced into the plurality of processing chambers; Equipped with setting an exhaust flow rate threshold (e.g., T0 relating to the exhaust flow rate threshold T) of the processing gas based on the exhaust flow rates of the plurality of first vacuum pumps; A vacuum exhaust system characterized in that the gas introduction amount control means controls at least one of the gas introduction timing (such as the opening timing of a chamber introduction valve device selected from chamber introduction valve devices 30-1 to 30-n) and flow rate (such as a flow rate according to the opening degree of a chamber introduction valve device) so as not to exceed the exhaust flow rate threshold. (2) The vacuum pumping system comprises: a first vacuum pump status information acquisition means (pressure sensor, motor 121, deposit sensor 34, APC valve device 40-1 to 40-n, pressure gauges 44-1 to 44-n, 48, etc.) for acquiring first vacuum pump status information (a signal indicating the pressure inside turbo molecular pumps 100-1 to 100-n, a signal indicating the magnitude of the current of motor 121, an output signal of deposit sensor 34, a signal indicating the opening degree of APC valve device 40-1 to 40-n, an output signal of pressure gauges 44-1 to 44-n, 48, etc.) which is information indicating the status of the plurality of first vacuum pumps; Further comprising: The vacuum exhaust system described in (1) above, characterized in that the exhaust flow rate threshold is adjusted by a signal from the first vacuum pump status information acquisition means (e.g., changed in an exhaust system control unit 20 or a process control unit that receives various signals). (3) The vacuum exhaust system according to (2) above, wherein the first vacuum pump status information includes information on a pressure status inside the first vacuum pump. (4) The vacuum pumping system comprises: pressure adjustment valves (such as valve bodies provided in APC valve devices 40-1 to 40-n) for adjusting pressures of the processing chambers, which are disposed upstream of the first vacuum pumps; A valve signal acquisition means (such as APC valve devices 40-1 to 40-n) for acquiring state information of the pressure regulating valve (such as a signal indicating a valve opening degree, information indicating a valve opening degree, etc.); Further comprising: The vacuum exhaust system described in (1) above, characterized in that the exhaust flow rate threshold is adjusted by a signal from the valve signal acquisition means (e.g., changed in the exhaust system control unit 20 that receives signals from the APC valve devices 40-1 to 40-n). (5) The vacuum pumping system comprises: A second pressure signal acquisition means (pressure gauges 44-1 to 44-n, etc.) for acquiring pressure information in the collecting pipe; Further comprising: The vacuum exhaust system described in (1) above, characterized in that the exhaust flow rate threshold is adjusted by a signal from the second pressure signal acquisition means (e.g., changed in the exhaust system control unit 20 that receives signals from pressure gauges 44-1 to 44-n). (6) The vacuum exhaust system comprises: A vacuum exhaust system described in any one of (1) to (5) above, characterized in that if the exhaust flow threshold is exceeded, an alarm is issued to the outside (such as outputting a signal or information from the exhaust system control unit 20 that can be used for warning or notification related to adjustment of the exhaust flow threshold T). (7) The vacuum exhaust system comprises: The vacuum exhaust system described in any one of (1) to (5) above, characterized in that when the amount of decrease in the adjusted exhaust flow rate threshold reaches a predetermined amount, an alarm is issued to the outside (such as outputting a signal or information from the exhaust system control unit 20 that can be used for warnings or notifications related to the maintenance of the system). (8) The vacuum exhaust system comprises: a gas introduction amount acquiring means for acquiring the amount of the gas introduced into the plurality of processing chambers (a gas introduction amount sensor, a means for calculating or acquiring information on the total flow rate from the detection result of the gas flow rate by the gas introduction amount sensor (exhaust system control unit 20 or other control unit), etc.); Further comprising: The vacuum exhaust system according to any one of claims 1 to 5, characterized in that the gas introduction amount control means controls at least one of the introduction timing and flow rate of the gas so that the introduction amount of the gas acquired by the gas introduction amount acquisition means does not exceed the exhaust flow rate threshold. (9) A vacuum pump used in a vacuum exhaust system (such as the vacuum exhaust system 10) for exhausting a processing gas (such as a process gas) from a plurality of processing chambers (such as the chambers 12-1 to 12-n), The vacuum pumping system includes: A plurality of first vacuum pumps (turbo molecular pumps 100-1 to 100-n, etc.); a collector pipe (such as the collector pipe 14) that connects exhaust ports (such as the exhaust port 133) of the plurality of first vacuum pumps in parallel; One or more second vacuum pumps (such as a dry pump 16) connected to the collecting pipe; A gas introduction amount control unit (exhaust system control unit 20, chamber introduction valve devices 30-1 to 30-n, etc.) for controlling a gas flow rate (amount of gas per unit time, etc.) introduced into the plurality of processing chambers; Equipped with setting an exhaust flow rate threshold (e.g., T0 relating to the exhaust flow rate threshold T) of the processing gas based on the exhaust flow rates of the plurality of first vacuum pumps; A vacuum pump used as the first vacuum pump in a vacuum exhaust system, characterized in that the gas introduction amount control means controls at least one of the gas introduction timing (such as the opening timing of a chamber introduction valve device selected from chamber introduction valve devices 30-1 to 30-n) and flow rate (such as a flow rate according to the opening degree of a chamber introduction valve device) so as not to exceed the exhaust flow rate threshold.

[0135] <Other> The present invention is not limited to the above-described embodiments, and various modifications and combinations of the embodiments are possible without departing from the scope of the present invention. [Explanation of symbols]

[0136] 10: Vacuum exhaust system 12-1 to 12-n: Chamber 14:Collecting pipe 14-1 to 14-n: Branch pipe section 15: Exhaust port 16: Dry pump 18: Collecting pipe section 20: Exhaust system control unit 30-1 to 30-n: Chamber introduction valve device 34: Depot sensor 40-1~10-n: APC valve device 44-1~44-n: Pressure gauge 100, 100-1 to 100-n: Turbo molecular pump 101: Air intake 121: Motor 133: Exhaust port

Claims

1. 1. A vacuum pumping system for evacuating process gases from a plurality of process chambers, comprising: The vacuum pumping system includes: a plurality of first vacuum pumps; a collecting pipe connecting exhaust ports of the plurality of first vacuum pumps in parallel; one or more second vacuum pumps connected to the collecting pipe; a gas introduction amount control unit for controlling a flow rate of gas introduced into the plurality of processing chambers; Equipped with setting an exhaust flow rate threshold of the processing gas based on the exhaust flow rates of the first vacuum pumps; A vacuum pumping system, characterized in that at least one of the gas introduction timing and flow rate is controlled by the gas introduction amount control means so that the exhaust flow rate threshold is not exceeded.

2. The vacuum pumping system includes: a first vacuum pump status information acquiring means for acquiring first vacuum pump status information which is information indicating the status of the plurality of first vacuum pumps; Further comprising: The vacuum pumping system of claim 1 , wherein the exhaust flow rate threshold is adjusted according to the first vacuum pump status information.

3. 3. The vacuum evacuation system according to claim 2, wherein the first vacuum pump status information includes information on a pressure status inside the first vacuum pump.

4. The vacuum pumping system includes: a pressure adjusting valve for adjusting the pressure of the processing chambers, the pressure adjusting valve being disposed upstream of the first vacuum pumps; A valve signal acquiring means for acquiring state information of the pressure regulating valve; Further comprising:

2. The vacuum exhaust system according to claim 1, wherein the exhaust flow rate threshold is adjusted by a signal from the valve signal acquisition means.

5. The vacuum pumping system includes: A second pressure signal acquiring means for acquiring pressure information in the collecting pipe; Further comprising:

2. The vacuum exhaust system according to claim 1, wherein the exhaust flow rate threshold is adjusted by a signal from the second pressure signal acquisition means.

6. The vacuum pumping system includes:

6. The vacuum exhaust system according to claim 1, wherein an alarm is issued to the outside when the exhaust flow rate threshold is exceeded.

7. The vacuum pumping system includes:

6. The vacuum exhaust system according to claim 1, further comprising an alarm outputting unit that outputs an alarm to an external device when the amount of decrease in the adjusted exhaust flow rate threshold reaches a predetermined amount.

8. The vacuum pumping system includes: a gas introduction amount acquisition unit for acquiring an introduction amount of the gas introduced into the plurality of processing chambers; Further comprising: A vacuum exhaust system as described in any one of claims 1 to 5, characterized in that the gas introduction amount control means controls at least one of the introduction timing and flow rate of the gas so that the introduction amount of the gas acquired by the gas introduction amount acquisition means does not exceed the exhaust flow rate threshold.

9. 1. A vacuum pump for use in a vacuum pumping system for evacuating process gases from a plurality of process chambers, comprising: The vacuum pumping system includes: a plurality of first vacuum pumps; a collecting pipe connecting exhaust ports of the plurality of first vacuum pumps in parallel; one or more second vacuum pumps connected to the collecting pipe; a gas introduction amount control unit for controlling a flow rate of gas introduced into the plurality of processing chambers; Equipped with setting an exhaust flow rate threshold of the processing gas based on the exhaust flow rates of the first vacuum pumps; At least one of the gas introduction timing and the gas flow rate is controlled by the gas introduction amount control means so that the exhaust flow rate threshold is not exceeded, The vacuum pump is A vacuum pump used as the first vacuum pump provided in the vacuum evacuation system.

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