Vacuum exhaust system and vacuum pump

Abstract

Provided is a vacuum exhaust system (10) for exhausting process gas from a plurality of chambers (10-1 to 10-n), the vacuum exhaust system (10) comprising 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 the process gas exhaust flow rate is set on the basis of the exhaust flow rates that the plurality of turbo molecular pumps (100-1 to 100-n) can achieve, and the gas introduction timing and / or flow rate are / 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).

Description

Vacuum pumping system and vacuum pump

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

[0002] Turbomolecular pumps are a type of vacuum pump known in the art. These pumps rotate rotors by energizing a motor within the pump body, expelling gas molecules from the process gas drawn into the pump body. Some turbomolecular pumps are equipped with heaters and cooling tubes to maintain proper temperature control within the pump.

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

[0004] Japanese Patent Application Laid-Open No. 2015-227618

[0005] A typical turbomolecular pump has a dependency on back pressure (secondary pressure) (called back pressure dependency), and if 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 pumping system is estimated by multiplying the number of process chambers (also called "processing chambers," "process 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. Therefore, 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) (to 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 pumping system.

[0007] An object of the present invention is to provide a vacuum pump for use in a vacuum pumping system and a vacuum pumping stem that allows for cost reduction, miniaturization, and / or increased flexibility in piping design.

[0008] (1) To achieve the above object, the present invention provides a vacuum exhaust system for exhausting process gas from a plurality of process chambers, the vacuum exhaust system comprising: 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; and a gas introduction rate control means for controlling the flow rate of gas introduced into the plurality of process chambers, the vacuum exhaust system being characterized in that an exhaust flow rate threshold for the process gas is set based on the exhaust flow rate of the plurality of first vacuum pumps, and at least one of the introduction timing and flow rate of the gas is controlled by the gas introduction rate control means so as not to exceed the exhaust flow rate threshold. (2) Also, to achieve the above object, the vacuum pump of the present invention is used as the first vacuum pump provided in the vacuum exhaust system.

[0009] According to the above invention, it is possible to provide a vacuum pump system and a vacuum pump used in a vacuum pump system that can reduce costs, reduce size, and / or improve the degree of freedom in piping design.

[0010] FIG. 1 is an explanatory diagram schematically showing the configuration of a vacuum pump and a vacuum exhaust system according to a first embodiment of the present invention. FIG. 2 is a circuit diagram of an amplifier circuit. FIG. 3 is a time chart showing control when a current command value is greater than a detection value. FIG. 4 is a time chart showing control when a current command value is smaller than a detection value. FIG. 5 is an explanatory diagram (a) schematically showing a concentrated exhaust type vacuum exhaust system according to an embodiment, and FIG. 6 is an explanatory diagram (b) schematically showing a distributed exhaust type vacuum exhaust system as a conventional example. FIG. 6 is a graph showing an example of changes in exhaust volume in one turbomolecular pump. FIG. 7 is a block diagram schematically showing an exhaust stem control unit.

[0011] <Turbo-molecular pump 100> 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 below with reference to the drawings. First, Fig. 1 shows a vertical cross-sectional view of a turbo-molecular pump 100 as a vacuum pump according to an embodiment of the present invention.

[0012] 1, a turbomolecular pump 100 has an intake port 101 formed at the upper end of a cylindrical outer cylinder 127. Inside the outer cylinder 127, a rotor 103 is provided, the rotor 103 having a plurality of rotors 102 (102a, 102b, 102c, ...) which are turbine blades for sucking in and exhausting gas, arranged radially and in multiple stages around its periphery. A rotor shaft 113 is attached to the center of the rotor 103, and the rotor shaft 113 is levitated and 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 upper radial electromagnet 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 changes in the inductance of the conductive windings, which change depending on 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 electromagnets 104. Such adjustment is performed independently in the X-axis direction and the Y-axis direction. In addition, the lower radial electromagnets 105 and the lower radial sensors 108 are arranged in the same manner as the upper radial electromagnets 104 and the upper radial sensors 107, and adjust the radial position of the lower side of the rotor shaft 113 in the same manner as the radial position of the upper side.

[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 highly magnetic permeable material such as iron. An axial sensor 109 is provided to detect the axial displacement of rotor shaft 113, and an axial position signal from the axial sensor 109 is sent to control device 200.

[0017] In the control device 200, a compensation circuit having, for example, a PID adjustment function generates excitation control command signals 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 each 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 forces that the axial electromagnets 106A and 106B exert on the metal disk 111, magnetically levitating the rotor shaft 113 in the axial direction and holding it in space without contact. The amplifier circuit 150 that controls the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 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. Motor 121 also incorporates a rotational speed sensor (not shown), such as a Hall element, resolver, or encoder, and the rotational speed of rotor shaft 113 is detected by the detection signal of this rotational speed sensor.

[0020] Furthermore, a phase sensor (not shown) is attached, for example, near the lower radial sensor 108, to detect the phase of rotation of the rotor shaft 113. The control device 200 uses the detection signals of both this phase sensor and the rotational speed sensor to detect the position of the magnetic pole.

[0021] A plurality of fixed blades 123 (123a, 123b, 123c...) are arranged at small gaps (predetermined intervals) from the rotating blades 102 (102a, 102b, 102c...). Each of the rotating blades 102 (102a, 102b, 102c...) is inclined 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.

[0022] Similarly, the fixed blades 123 are formed at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, and are arranged in a staggered manner 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 by being inserted between a plurality of stacked fixed blade spacers 125 (125a, 125b, 125c, ...).

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

[0024] Furthermore, depending on the application of the turbomolecular pump 100, a threaded spacer 131 is disposed between the lower part of the fixed vane spacer 125 and the base portion 129. The threaded spacer 131 is a cylindrical member made of a metal such as aluminum, copper, stainless steel, iron, or an alloy containing any of these metals, and has a plurality of spiral thread grooves 131a engraved on its inner circumferential surface. The spiral direction of the thread grooves 131a corresponds to the direction in which exhaust gas molecules are transported toward the exhaust port 133 when they move in the rotation direction of the rotor 103. A rotor lower cylindrical portion 103b hangs down 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, with a predetermined gap separating them from the inner peripheral surface of the threaded spacer 131. Exhaust gas transferred to the thread groove 131a by the rotor 102 and fixed blades 123 is guided along the thread groove 131a and sent to the base portion 129. In this manner, the threaded spacer 131 and the opposing rotor lower cylindrical portion 103b constitute a Holweck-type exhaust mechanism 204. The Holweck-type exhaust mechanism 204 imparts 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 turbomolecular pump 100.

[0025] The base portion 129 is a disk-shaped member that forms the base of the turbomolecular pump 100, and is generally made of metal such as iron, aluminum, stainless steel, etc. The base portion 129 not only physically holds the turbomolecular pump 100, but also functions as a heat conduction path, so it is desirable to use a metal that is rigid and has high thermal conductivity, such as iron, aluminum, or copper.

[0026] In this configuration, when the rotor 102 is driven to rotate together with the rotor shaft 113 by the motor 121, the action of the rotor 102 and the stator 123 causes exhaust gas to be drawn from the chamber through the intake port 101. The exhaust gas drawn in through the intake port 101 passes between the rotor 102 and the stator 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 conduction of heat generated by the motor 121, but this heat is transferred to the stator 123 side by radiation or conduction by gas molecules of the exhaust gas.

[0027] The stator spacers 125 are joined together at their outer peripheries and transmit to the outside heat received by the stator 123 from the rotor 102 and frictional heat generated when exhaust gas comes into contact with the stator 123 .

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

[0029] Depending on the application of the turbomolecular pump 100, the electrical equipment section may be covered by a stator column 122 to prevent the gas sucked in from the intake port 101 from entering the electrical equipment section, which is composed 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., and the interior 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 referred to as 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 numeral 210 in FIG. 5A) between the protective bearing 120 and the rotor shaft 113, between the rotor and stator of the motor 121, and between the stator column 122 and the inner cylindrical portion of the rotor blades 102 (lower cylindrical portion 103b of the rotor) or 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 specific to the model. To store these control parameters, the turbomolecular pump 100 is provided with an electronic circuit unit 141 within its body. The electronic circuit unit 141 is composed of a semiconductor memory such as an EEPROM, electronic components such as semiconductor devices for accessing the memory, and a substrate 143 for mounting these components. The electronic circuit unit 141 is housed below a rotational speed sensor (not shown) near the center of a base unit 129 that constitutes the lower part of the turbomolecular pump 100, and is closed by an airtight bottom lid 145.

[0032] In the semiconductor manufacturing process, some process gases introduced into a chamber have the property of solidifying when their pressure exceeds a predetermined value or their temperature falls below a predetermined value. Inside the turbomolecular pump 100, the pressure of the exhaust gas is lowest at the inlet 101 and highest at the outlet 133. If the pressure of the process gas exceeds a predetermined value or the temperature falls below a predetermined value while the process gas is being transferred from the inlet 101 to the outlet 133, the process gas solidifies and adheres to and accumulates inside the turbomolecular pump 100.

[0033] For example, when SiCl4 is used as the process gas in an Al etching apparatus, the vapor pressure curve shows that at low vacuum (760 torr to 10-2 torr) and low temperature (approximately 20°C), a solid product (e.g., AlCl3) precipitates and adheres to and accumulates inside the turbomolecular pump 100. As a result, when precipitates of the process gas accumulate inside the turbomolecular pump 100, these deposits narrow the pump flow path, causing a decrease in the performance of the turbomolecular pump 100. Furthermore, the above-mentioned product is prone to solidification and adhesion in high-pressure areas near the exhaust port and near the threaded spacer 131.

[0034] To solve this problem, conventionally, a heater (not shown) or an annular (ring-shaped) water-cooled pipe 149 is wound around the outer periphery of the base portion 129 or the like, and a temperature sensor (e.g., a thermistor) (not shown) is embedded in the base portion 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 maintain the temperature of the base portion 129 at a constant high temperature (set temperature) (hereinafter referred to as TMS; Temperature Management System). In the turbomolecular pump 100 of the first embodiment, a large amount of hot air (high-temperature fluid, heating fluid) is introduced into the turbomolecular pump 100 to heat and vaporize (clean) the deposits. Vaporization of deposits by hot air will be described later.

[0035] Next, regarding the turbomolecular pump 100 configured as described above, 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 will be described. A circuit diagram of this amplifier circuit is shown in FIG.

[0036] 2, one end of the electromagnet winding 151 constituting the upper radial electromagnet 104 and the like is connected to the positive electrode 171a of the power supply 171 via a transistor 161, and the other end is connected to the negative electrode 171b of the power supply 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 diode cathode terminal 161a 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 diode cathode terminal 162a connected to the current detection circuit 181 and an anode terminal 162b connected to the negative electrode 171b.

[0038] Meanwhile, the current regenerating 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 regenerating 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 detecting circuit 181. The current detecting circuit 181 is configured, for example, by a Hall sensor type current sensor or an electrical resistance element.

[0039] The amplifier circuit 150 configured as described above corresponds to one electromagnet. Therefore, if the magnetic bearing is controlled in 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 in the figure of the control device 200, and this amplifier control circuit 191 is configured to switch the transistors 161 and 162 on / off.

[0041] The amplifier control circuit 191 compares 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. Based on the comparison result, the amplifier control circuit 191 determines the magnitude of the pulse width (pulse width times Tp1 and Tp2) to be generated within a control cycle Ts, which is one period of PWM control. As a result, gate drive signals 191a and 191b having these pulse widths are output from the amplifier control circuit 191 to the gate terminals of the transistors 161 and 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 acceleration of its rotational speed or when a disturbance occurs during 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 electrode 171a and the negative electrode 171b of the power supply 171 to stabilize the power supply 171.

[0043] In this configuration, when both the transistors 161 and 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] Furthermore, when one of the transistors 161 and 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, 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 and 162 in this manner, high-frequency noise such as harmonics generated in the turbomolecular 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 transistors 161 and 162 are turned on for a time period corresponding to a pulse width time Tp1 only once during 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, if the detected current value is greater than the current command value, both transistors 161 and 162 are turned off for a time period corresponding to 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 electrode 171b to the positive electrode 171a via 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) serves as an intake section connected to the target device, and the lower side (the side on which the exhaust port 15 constituting the exhaust port 133 is provided on the base portion 129 so as to protrude to the right in the figure) serves as an exhaust section connected to an auxiliary pump (not shown) (a dry pump 16 to be described later, also referred to as a "back pump") or the like. The turbomolecular pump 100 can be used not only in the vertical position shown in Figure 1, but also in an inverted position, a horizontal position, or an inclined position.

[0049] In the turbomolecular pump 100, the aforementioned outer cylinder 127 and base portion 129 are combined to form a single case (hereinafter, both may be collectively referred to as the "main body casing" or the like). The turbomolecular pump 100 is electrically (and structurally) connected to a box-shaped electrical equipment case (not shown), and the aforementioned control device 200 is incorporated into 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 using the motor 121, and an exhaust mechanism portion that is rotationally driven by the rotation mechanism portion. The exhaust mechanism portion can be divided into a turbomolecular pump mechanism portion that is composed of the rotor blades 102, fixed blades 123, and the like, and a threaded pump mechanism portion (a Holweck-type exhaust mechanism portion 204) that is composed of the rotor lower cylindrical portion 103b, threaded spacer 131, and the like.

[0051] The aforementioned purge gas (protective gas) is used to protect the bearing parts, the rotor blades 102, etc., to prevent corrosion caused by the exhaust gas (process gas), and to cool the rotor blades 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. 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 "touchdown (T / D) bearings," "backup bearings," etc. These protective bearings 120 prevent the position and attitude of the rotor shaft 113 from changing significantly, even in the unlikely event of a problem with the electrical system or atmospheric inrush, thereby preventing damage to the rotor blades 102 and their surrounding areas.

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

[0055] <Vacuum Exhaust System 10> <<Basic Configuration of Vacuum Exhaust System 10>> Figure 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 turbomolecular pumps 100. In the following description, the plurality of (here, n) turbomolecular pumps 100 will be appropriately designated by the reference numerals "100-1" to "100-n." Here, "n" represents an integer of 2 or greater. The same applies to "n" in the chambers 12-1 to 12-n described below.

[0056] Each of the turbomolecular pumps 100-1 to 100-n is connected to one dry pump 16 via a collecting pipe 14. The dry pump 16 has functions such as maintaining the back pressure of the plurality of turbomolecular 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 pumping system 10 is used to evacuate gases (such as process gases) from a plurality of chambers (processing chambers) 12-1 to 12-n of a semiconductor manufacturing apparatus (such as a semiconductor or flat panel manufacturing apparatus). Turbomolecular 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 may be provided around the chambers 12-1 to 12-n. A roughing vacuum pump is connected to the transfer chamber and the load lock chamber, creating a vacuum within the transfer chamber and the load lock chamber. The load lock chamber enables the transfer of semiconductors and other materials between the vacuum space within the transfer chamber and an atmospheric pressure region while maintaining the vacuum within the transfer chamber. A transfer robot is disposed within the transfer chamber, and the transfer robot transfers semiconductors and other materials to one of the chambers 12-1 to 12-n. Process gases and other gases are supplied to each of the chambers 12-1 to 12-n.

[0059] In the example of Figure 5(a), one turbomolecular pump 100-1 to 100-n is connected to each of the chambers 12-1 to 12-n. However, for example, multiple turbomolecular pumps may be connected to one chamber. Also, one turbomolecular 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 turbomolecular 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 fails.

[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 will be described later, the vacuum pumping system 10 also has a function for controlling the introduction of gas into the chambers 12-1 to 12-n. However, the function for 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 pumping system 10 and the other device or system may be collectively referred to as, for example, a "system" or an "overall system."

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

[0064] 5B, dry pumps 16-1 to 16-n are connected to the individual turbo molecular pumps 100-1 to 100-n, respectively, resulting in a large number of dry pumps 16-1 to 16-n, and therefore a corresponding increase in costs.

[0065] Furthermore, dry pumps (such as the dry pumps 16-1 to 16-n) typically 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 turbomolecular 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 the 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 collecting pipe 14 on the collected side is connected to the intake port (not shown) of the dry pump 16.

[0068] Hereinafter, the pipe sections on the branched side of the collecting pipe 14 will be referred to as "branch pipe sections" and will be given reference numerals 14-1 to 14-n. Furthermore, the pipe section on the collected side of the collecting pipe 14 will be referred to as "collecting pipe section" and will be given reference numeral 18. Note that the "n" in the branch pipe sections 14-1 to 14-n of the collecting pipe 14 may not necessarily match the "n" in the turbomolecular pumps 100-1 to 100-n. Furthermore, 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 vacuum pumping system 10, one dry pump 16 is assigned to multiple turbomolecular pumps 100-1 to 100-n, and the number of dry pumps 16 is smaller than in the distributed exhaust vacuum system 50 (FIG. 5B). This reduces 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, even the centralized exhaust vacuum pumping system 10 has some problems unless it is designed in a way similar to that of this embodiment (described later). For example, to ensure sufficient exhaust from the multiple chambers 12-1 to 12-n and turbomolecular pumps 100-1 to 100-n, and exhaust through long flow paths (pipes), it is necessary to use a dry pump 16 that is larger (higher speed, with a higher pumping speed) than the individual dry pumps 16-1 to 16-n of the decentralized vacuum pumping system 50 (FIG. 5B).

[0071] Furthermore, the turbomolecular pumps 100-1 to 100-n must be of a type that can maintain the intake pressure even when 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 in the distributed vacuum pumping system 50 (FIG. 5(b)).

[0072] Furthermore, when the inventors initially developed the centralized exhaust vacuum pumping system 10, they assumed that the back pressure of the turbomolecular pumps 100-1 to 100-n would be the back pressure (turbo back pressure) when the flow rates of all the systems were simultaneously at their maximums. However, when they measured the exhaust rates of each of the turbomolecular pumps 100-1 to 100-n in an actual process, they found that there were only a few cases where the maximum flow rate (Qmax, for example, 3000 sccm) of a particular turbomolecular pump was exceeded, as shown in the graph of FIG.

[0073] Here, the horizontal axis of FIG. 6 represents time, and the vertical axis represents the displacement (flow rate) of a particular turbomolecular pump at each moment during operation. In the example of FIG. 6 , the displacement increases stepwise over time, reaches a maximum value (Qmax for a particular turbomolecular pump) in the middle, and then decreases stepwise thereafter. The time period during which the maximum value is reached is only a portion of the entire operating period, and during other time periods, the pump is operated at a displacement rate lower than the maximum value (Qmax). Note that flow rate changes such as those shown in the example of FIG. 6 also occur in other turbomolecular pumps, and the sum of the flow rates at a given time is the total flow rate at that time. The nature of the flow rate changes typically differs among multiple turbomolecular pumps. However, the nature of the flow rate changes may be common to some of the multiple turbomolecular pumps.

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

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

[0076] (1) The start timing of the process is adjusted so that the total flow rate (Q=Q1+Q2+Q3+...+Qn, the total introduction rate, which is the sum of the amounts of gas introduced into the individual chambers) related to the turbomolecular 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 rate, total introduction rate) at each of the turbomolecular pumps 100-1 to 100-n at that time.

[0077] Typically, 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 up to the time when the process is started in each of the 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 the threshold value so that the total flow rate does not exceed the threshold value. In this way, the total flow rate at that 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 given moment in the entire system that is assumed when designing the vacuum pumping system 10. It can also be set as the maximum flow rate per chamber x the number of chambers x a coefficient (safety factor < 1) or the average flow rate per chamber x the number of chambers x a 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 based on the above-mentioned threshold value at a timing that prevents the expected total flow rate from exceeding the 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" refers to the piping that connects the turbomolecular 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 degradation occurs due to the blockage of the gas flow path caused by deposits. Foreline degradation occurs due to blockage of the piping caused by deposits, a decrease in dry performance (performance of the dry pump), etc. Therefore, the total flow rate threshold is changed depending on the degree of such degradation.

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

[0082] Furthermore, the information used to evaluate the degree of deterioration includes, for example, a to e. a. Increase in pressure (intake pressure, exhaust port pressure, screw inlet, etc.) inside the turbomolecular pump (here, turbomolecular pumps 100-1 to 100-n). b. Increase in motor current (here, the value of the current flowing through the motor 121). c. Increase in output of the deposit sensor (deposit sensor) due to the occurrence or increase of deposits. d. APC (Automatic Pressure Control) valve opening installed at the intake port (here, intake port 101) of the turbomolecular pump (here, turbomolecular pumps 100-1 to 100-n). e. Increase in pressure in the foreline piping.

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

[0084] <<Specific Example of Adjustment of Total Flow Rate>> Based on this concept, the vacuum pumping system 10 according to this embodiment is equipped with the turbomolecular pumps 100-1 to 100-n, the collecting pipe 14, and the dry pump 16, as described above. The vacuum pumping system 10 further includes an exhaust system control unit 20. As shown schematically 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 gas introduction 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 turbomolecular 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 turbomolecular 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 timing of gas introduction 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 timing of gas introduction (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) located 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 is changed from a closed state to an open state, allowing the gas to flow in.

[0089] Furthermore, 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, processes are performed in the chambers 12-1 to 12-n 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 chamber introduction valve device 30-1 to 30-n and the gas flow rate information of each turbomolecular pump 100-1 to 100-n can be known (determined) in advance.

[0091] In the exhaust system control unit 20, for example, by adding 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 typically increases over time. Note that in this description, the gas flow rates of the turbomolecular pumps 100-1 to 100-n are assumed to be equal to the gas flow rates associated with the chambers 12-1 to 12-n.

[0092] A predetermined exhaust flow rate threshold T is stored in the memory unit 24 of the exhaust system control unit 20. For example, when the vacuum exhaust system 10 starts operating (begins use), no deposits are present and the vacuum exhaust system 10 is in a clean state. In such a case, the exhaust flow rate threshold T is set to an initial value T0. The initial value T0 of the exhaust flow rate threshold 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 high 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 control of the opening timing and / or the opening degree 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 target chamber introduction valve device 30-1 to 30-n. After that (for example, after several seconds to several tens of seconds), the target 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 gas introduction is restored 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, thereby suppressing an increase in the total flow rate Q. The exhaust system control unit 20 then introduces or increases the gas into the selected chamber, supplying the planned amount of gas to the selected chamber. In this case, the exhaust system control unit 20 also controls the gas supply so that Q≧T does not occur.

[0096] 5A, the virtual control ranges indicated by the reference numerals 32 and 33 are the control ranges of the exhaust system control unit 20. In the example of FIG. 5A, one control range 32 of the exhaust system control unit 20 includes the turbomolecular pumps 100-1 to 100-n and the dry pump 16. The other control range 33 of the exhaust system control unit 20 includes the 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 and 33 are connected by a dotted line, which schematically 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 and 33.

[0098] The aforementioned "system" and "overall system" include these control ranges 32 and 33 as well as peripheral devices and systems. For example, it is possible to set only some of the devices including the turbomolecular pumps 100-1 to 100-n (or only the turbomolecular pumps 100-1 to 100-n) as the direct control range of the exhaust system control unit 20 (the components 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 control the supply of gas to the chambers 12-1 to 12-n (such as the opening and closing and degree of opening of the chamber introduction valve devices 30-1 to 30-n). For example, the exhaust system control unit 20 may issue an alarm (warning, notification) outside the vacuum exhaust system 10 when the total flow rate Q exceeds the exhaust flow rate threshold T.

[0100] The "alarm" here may be an electrical (or electronic) signal (information). For example, based on the output alarm, a control unit of the process control system (process control unit, not shown) can suppress the supply of gas to the chambers 12-1 to 12-n to prevent the total flow rate Q from exceeding the exhaust flow rate threshold T.

[0101] The "alarm" can also be output to a notification device (warning device) such as a display device (not shown) such as a liquid crystal display or a speaker (not shown). In this case, an operator who perceives the content (display content) displayed on the display device or the sound emitted from the speaker (not shown) can adjust the gas supply to chambers 12-1 to 12-n or input instructions to a device that adjusts the gas supply.

[0102] <<Specific Example of Adjustment of Exhaust Flow Rate Threshold T>> When the vacuum exhaust system 10 starts operating and gas is continuously exhausted from the chambers 12-1 to 12-n, deposits are typically generated and 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 T in accordance with the degree of deterioration.

[0103] When deterioration has progressed to a predetermined level, the exhaust system control unit 20 lowers the exhaust flow rate threshold T from the initial value T0 to T1, which is lower than T0. Furthermore, as deterioration progresses further, the exhaust flow rate threshold T is lowered from T1 to T2 (< T1). This adjustment of the exhaust flow rate threshold T can be performed in stages to lower it to T2, T3, T4, ... (T2 > T3 > T4 ...) depending on the degree of deterioration.

[0104] <<Example of Evaluation Index (Pressure)>> Information for evaluating the degree of deterioration of the vacuum exhaust system 10 (evaluation index for the degree of deterioration) is used to adjust the exhaust flow rate threshold T. As the evaluation index, various parameters indicating the state of vacuum exhaust can be used.

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

[0106] Although not shown, in the case of the turbomolecular pump 100 illustrated in FIG. 1 , 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 (Hollweck-type exhaust mechanism 204). Various types of pressure sensors, including common 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 (measured 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, using the pressure value (design value, theoretical value) at the time when the turbomolecular pump 100 starts operating (starts using). 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] The exhaust system control unit 20 compares the calculated pressure with the pressure at the start of operation (start of use) of the turbomolecular pump 100. If it is determined that the actual pressure measurement value (actual pressure measurement value) has increased by a predetermined value (or a predetermined percentage) or more relative to the reference pressure 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 total flow rate Q as described above. 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 flowing through the motor 121 (motor current) as an evaluation index for the degree of deterioration. This corresponds to "b." among the above-mentioned ideas "a." to "e." As deterioration of the vacuum exhaust system 10 progresses, the value of the motor current in the turbomolecular pump 100 becomes larger than when deterioration is not progressing, in order to obtain the target gas flow rate and rotation speed. Therefore, 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 changes in motor current can be stored in a table, and the exhaust system control unit 20 can determine the degree of deterioration by referring to the table for the detected motor current. 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 electromagnet current iL flowing through the electromagnet winding 151 (FIG. 2) described above or the detection results of other currents.

[0112] <<Another Example of Evaluation Index (Amount of Deposits)>> Furthermore, an increase in output from a deposit sensor (deposit sensor) due to the occurrence or increase of deposits can also be used as an evaluation index for 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, in a location in the turbomolecular pump 100 (FIG. 1) where deposits are likely to occur. More specifically, a location downstream of the exhaust gas (process gas) in the turbomolecular pump 100 can be used. Even more specifically, a location on the inner bottom of the base 129 facing the Holweck-type exhaust mechanism 204 or the lower cylindrical portion 103b of the rotor can be used. The deposit sensor can also be located closer to the exhaust port 133.

[0114] <<Another Example of Evaluation Index (APC Valve Opening)>> Furthermore, the valve openings (APC valve opening, valve disc opening, valve disc opening) of the APC (Automatic Pressure Control) valve devices 40-1 to 40-n can be used as an evaluation index for the degree of deterioration. This corresponds to "d." among the above-mentioned "a." to "e."

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

[0116] When the amount of deposits increases in any one of the turbomolecular 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 automatically increases its opening to control the gas flow rate to the corresponding turbomolecular pump, thereby maintaining the gas flow rate. The decrease in the gas flow rate can be determined by the average opening of the multiple APC valve devices or when the opening of a specific (e.g., one) APC valve device is higher than a planned value.

[0117] In this way, the APC valve opening changes in response to a change (decrease) in the gas flow rate in the turbomolecular 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 based on the APC valve opening.

[0118] <<Example of Evaluation Index (Foreline Pressure Rise)>> It is also possible to use pressure rise in the foreline piping as an evaluation index for the degree of deterioration. This corresponds to "e." of the above-mentioned concepts "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] 5A, 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 their output signals depending on 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, 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 if the pressure rises above a reference value (pressure threshold), the exhaust system control section 20 issues an alarm (warning, notification) to the outside to notify of an abnormality in the vacuum exhaust system 10 or for maintenance, for example.

[0120] <<Alarm for Maintenance>> The exhaust system control unit 20 issues an alarm externally 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 when it has decreased to the predetermined value or less, issues an alarm (warning, notification) externally to the vacuum exhaust system 10.

[0121] The "alarm" here may be an electrical (or electronic) signal (information). For example, it is possible to connect a cleaning device (e.g., a plasma cleaning device, not shown) to the turbomolecular pump 100, and based on the output alarm, stop the normal operation of the turbomolecular pump 100 and operate the cleaning device.

[0122] It is also possible to output the "alarm" to a notification device (warning device), such as the aforementioned 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 and clean the turbomolecular pumps 100-1 to 100n.

[0123] <Advantages of the Invention According to the Embodiment> According to the vacuum exhaust system 10 of the embodiment as described above, the gas introduction amount control means controls at least one of the gas introduction timing and flow rate so that the total flow rate Q of the turbomolecular 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 time low. It is also 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, use piping with low conductance, or adopt a turbomolecular pump with excellent back pressure dependency. This makes it possible to provide a vacuum pumping system 10 that allows for cost reduction and miniaturization of the exhaust system and / or improved flexibility in piping design, as well as vacuum pumps (turbomolecular pumps 100-1 to 100-n) that can be used in the vacuum pumping system.

[0125] Furthermore, according to the vacuum pumping system 10 of this embodiment, the exhaust flow rate threshold T is adjusted based on signals related to the following conditions: a. An increase in pressure (intake pressure, exhaust port pressure, screw inlet, etc.) within the turbomolecular pump (here, turbomolecular pumps 100-1 to 100-n); b. An increase in motor current (here, the value of the current flowing through the motor 121); c. An increase in output from a deposit sensor (deposit sensor) due to the generation or increase of deposits; d. An automatic pressure control (APC) valve opening installed at the intake port (here, intake port 101) of the turbomolecular pump (here, turbomolecular pumps 100-1 to 100-n); and e. An increase in pressure in the foreline piping. Therefore, the exhaust flow rate threshold T can be adjusted based on the detected degree of deterioration at each location in the vacuum pumping system 10 and its surroundings. This makes it possible to appropriately set the exhaust flow rate threshold T according to the degree of deterioration each time.

[0126] It should be noted that the above "a." to "c." can be considered to be items (also referred to as "parameters") that indicate the degree of deterioration in the turbomolecular pumps 100-1 to 100-n. The above "d." to "e." can be considered to be items that indicate the degree of deterioration outside the turbomolecular pumps 100-1 to 100-n.

[0127] Additionally, "a." to "c." can be considered 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 countermeasures based on this "alarm." These countermeasures include various operations and controls (including manual and automatic operations) 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 sequentially adjusted, causing the exhaust flow rate threshold T to change over time (chronological change). 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 or information. Therefore, it becomes possible to take measures based on this "alarm."

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

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

[0132] The gas introduction amount obtaining means includes means (gas introduction amount sensors) for detecting the amount of gas flowing into, passing through, and / or flowing out of chambers 12-1 to 12-n, and means for calculating or obtaining 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 means for calculating or obtaining information on various introduction amounts.

[0133] Furthermore, the turbomolecular pumps 100-1 to 100-n used in the vacuum pumping system 10 as described above contribute to the construction of the vacuum pumping 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 exhaust system comprising: a plurality of first vacuum pumps (such as turbo molecular pumps 100-1 to 100-n); a collecting pipe (such as collecting pipe 14) connecting exhaust ports (such as exhaust port 133) of the plurality of first vacuum pumps in parallel; one or more second vacuum pumps (such as dry pump 16) connected to the collecting pipe; and a gas introduction amount control means (such as exhaust system control unit 20, chamber introduction valve devices 30-1 to 30-n) for controlling the flow rates (such as the amount of gas per unit time) of gas introduced into the plurality of processing chambers, and setting an exhaust flow rate threshold (such as T0 related to the exhaust flow rate threshold T) of the processing gas based on the flow rates that can be exhausted by 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 that the exhaust flow rate threshold is not exceeded. (2) The vacuum exhaust system according to (1), further comprising: first vacuum pump status information acquisition means (pressure sensors, motors 121, deposit sensors 34, APC valve devices 40-1 to 40-n, pressure gauges 44-1 to 44-n, 48, etc.) for acquiring first vacuum pump status information indicating the status of the plurality of first vacuum pumps (a signal indicating the pressure inside the turbomolecular pumps 100-1 to 100-n, a signal indicating the magnitude of the current of a motor 121, an output signal of a deposit sensor 34, a signal indicating the aperture of an APC valve device 40-1 to 40-n, an output signal of pressure gauges 44-1 to 44-n, 48, etc.), wherein the exhaust flow rate threshold is adjusted by a signal from the first vacuum pump status information acquisition means (e.g., changed by an exhaust system control unit 20 or a process control unit that receives various signals). (3) The vacuum exhaust system according to (2), wherein the first vacuum pump status information includes information about the pressure state inside the first vacuum pump.(4) The vacuum exhaust system according to (1) above, further comprising: pressure adjustment valves (such as valve bodies provided in APC valve devices 40-1 to 40-n) for adjusting the pressures of the processing chambers, which are arranged upstream of the first vacuum pumps; and valve signal acquisition means (such as APC valve devices 40-1 to 40-n) for acquiring status information of the pressure adjustment valves (such as signals indicating valve openings, information indicating valve openings), and the exhaust flow rate threshold is adjusted by a signal from the valve signal acquisition means (such as being changed in an exhaust system control unit 20 that receives a signal from the APC valve devices 40-1 to 40-n). (5) The vacuum exhaust system according to (1) above, further comprising: a second pressure signal acquisition means (such as pressure gauges 44-1 to 44-n) that acquires pressure information inside the collecting pipe; and the exhaust flow rate threshold is adjusted by a signal from the second pressure signal acquisition means (such as by being changed by the exhaust system control unit 20 that receives the signals from the pressure gauges 44-1 to 44-n). (6) The vacuum exhaust system according to any one of (1) to (5) above, characterized in that when the exhaust flow rate threshold is exceeded, the vacuum exhaust system issues an alarm to the outside (such as by outputting a signal or information from the exhaust system control unit 20 that can be used for an alarm or notification related to the adjustment of the exhaust flow rate threshold T). (7) The vacuum exhaust system according to any one of (1) to (5) above, characterized in that when a decrease in the adjusted exhaust flow rate threshold reaches a predetermined amount, the vacuum exhaust system issues an alarm to the outside (such as by outputting a signal or information from the exhaust system control unit 20 that can be used for an alarm or notification related to system maintenance).(8) The vacuum exhaust system described in any one of (1) to (5) above further comprises a gas introduction amount acquisition means (such as a gas introduction amount sensor, a means (exhaust system control unit 20 or another control unit) for calculating or acquiring information on the total flow rate from the gas flow rate detection results by the gas introduction amount sensor, etc.) for acquiring the introduction amount of the gas introduced into the plurality of processing chambers, and 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 chambers 12-1 to 12-n), the vacuum exhaust system comprising: a plurality of first vacuum pumps (such as turbomolecular pumps 100-1 to 100-n); a collecting pipe (such as the collecting pipe 14) connecting 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 the dry pump 16) connected to the collecting pipe; and a gas introduction amount control means (such as the exhaust system control unit 20, chamber introduction valve devices 30-1 to 30-n) for controlling a gas flow rate (such as an amount of gas per unit time) introduced into the plurality of processing chambers, the vacuum exhaust system setting an exhaust flow rate threshold (such as T0 related to the exhaust flow rate threshold T) for the processing gas based on the flow rates that can be exhausted by the plurality of first vacuum pumps, a gas introduction amount control means for controlling at least one of the gas introduction timing (e.g., opening timing of a chamber introduction valve device selected from chamber introduction valve devices 30-1 to 30-n) and the gas flow rate (e.g., a flow rate according to the opening degree of the chamber introduction valve device) so that the exhaust flow rate threshold is not exceeded;

[0135] <Others> 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 gist of the present invention.

[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 section 30-1 to 30-n: Chamber introduction valve device 34: Deposit sensor 40-1 to 10-n: APC valve device 44-1 to 44-n: Pressure gauge 100, 100-1 to 100-n: Turbo molecular pump 101: Intake port 121: Motor 133: Exhaust port

Claims

1. A vacuum exhaust system for exhausting processing gas from a plurality of processing chambers, comprising: 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; and a gas introduction amount control means for controlling a flow rate of gas introduced into the plurality of processing chambers, wherein an exhaust flow rate threshold for the processing gas is set based on the exhaust flow rates of the plurality of first vacuum pumps, and at least one of the introduction timing and flow rate of the gas is controlled by the gas introduction amount control means so as not to exceed the exhaust flow rate threshold.

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

3. The vacuum exhaust system according to claim 2, wherein said first vacuum pump status information includes information on a pressure status within said first vacuum pump.

4. The vacuum exhaust system according to claim 1, further comprising: a pressure regulating valve for regulating the pressure of the multiple processing chambers, the pressure regulating valve being arranged upstream of the multiple first vacuum pumps; and a valve signal acquiring means for acquiring status information of the pressure regulating valve, wherein the exhaust flow rate threshold is adjusted by a signal from the valve signal acquiring means.

5. The vacuum exhaust system according to claim 1, further comprising: a second pressure signal acquisition means for acquiring pressure information inside the collecting pipe; and the exhaust flow rate threshold is adjusted by a signal from the second pressure signal acquisition means.

6. The vacuum exhaust system according to any one of claims 1 to 5, characterized in that, when the exhaust flow rate threshold is exceeded, an alarm is issued to the outside.

7. The vacuum exhaust system according to any one of claims 1 to 5, characterized in that the vacuum exhaust system issues an alarm to the outside when the amount of decrease in the adjusted exhaust flow rate threshold reaches a predetermined amount.

8. The vacuum exhaust system according to any one of claims 1 to 5, further comprising a gas introduction amount acquisition means for acquiring an introduction amount of the gas to be introduced into the multiple processing chambers, and wherein at least one of the introduction timing and flow rate of the gas is controlled by the gas introduction amount control means 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 for exhausting processing gas from a plurality of processing chambers, the vacuum exhaust system comprising: 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; and a gas introduction amount control means for controlling the flow rate of gas introduced into the plurality of processing chambers, characterized in that an exhaust flow rate threshold for the processing gas is set based on the exhaust flow rates of the plurality of first vacuum pumps, and at least one of the introduction timing and flow rate of the gas is controlled by the gas introduction amount control means so as not to exceed the exhaust flow rate threshold, and the vacuum pump is used as the first vacuum pump provided in the vacuum exhaust system.

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