Vacuum exhaust device

Abstract

To provide an evacuation device having an excellent cleaning effect at low cost.SOLUTION: An evacuation device comprises a plasma generation device 210. The plasma generation device 210 includes a plasma generation chamber 230 formed in a cathode electrode part 216, a fuel gas supply port part 214 arranged in an annular flow passage, a second insulation part 220 arranged in the plasma generation chamber 230, a connector 222 arranged in the plasma generation chamber 230, and a first insulation part 218, etc. for electrically insulating the plasma generation chamber 230. Radicals can be supplied from the second insulation part 220 to the inside of a case composed of an outer cylinder, etc.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a vacuum exhaust device using a vacuum pump such as a turbomolecular pump. [Background technology]

[0002] Turbomolecular pumps are commonly known as a type of vacuum pump. These turbomolecular pumps are used, for example, for exhausting gases in manufacturing equipment for semiconductors, flat panels, and the like. In turbomolecular pumps, a motor inside the pump body is energized to rotate rotors, which eject gas molecules (gas molecules) from the gas (process gas) drawn into the pump body, thereby exhausting the gas. Some turbomolecular pumps are equipped with heaters and cooling tubes to properly manage the temperature inside the pump.

[0003] In vacuum pumps used for exhausting gas from manufacturing equipment for semiconductors, flat panels, etc., reaction products generated during the manufacturing process of semiconductors and flat panels can accumulate inside the vacuum pump. As a countermeasure, a technology has been devised in which a plasma generator is installed in the vacuum pump and the inside of the pump is plasma cleaned.

[0004] In the invention disclosed in Patent Document 1, a plasma introduction port (radical supply port 201a) is provided in the casing (external cylinder 127) of a vacuum pump, and a plasma generator (radical supply means 201) is connected to the plasma introduction port. Radicals introduced into the casing flow circumferentially through an annular passage (annular groove) formed between the inner wall of the casing and the outer wall of the exhaust mechanism. The radicals are then introduced into the exhaust mechanism through a communication port provided in a spacer (stationary blade spacer 125) that holds the stator blade (stationary blade 123). This communication port is provided facing the space created by widening the gap between the rotor blade (rotor blade 102) and the stator blade in the direction of the rotation axis. Therefore, the larger the communication port (the diameter or opening area of ​​the communication port), the wider the gap between the rotor blade and the stator blade, resulting in a decrease in pump performance. For this reason, the size of the communication port has been minimized, and multiple communication ports and plasma generators (radical supply means 201) have been provided circumferentially. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-017864 Summary of the Invention [Problem to be solved by the invention]

[0006] The radicals used in plasma cleaning are substances that are forcibly dissociated by applying high energy inside the plasma generator. Because of this, radicals have a short lifespan, and it has sometimes been impossible to supply radicals to areas far from the plasma generator. In order to supply radicals evenly at a similar concentration throughout the entire pump, it has been necessary to arrange multiple plasma generators in the circumferential direction.

[0007] When multiple plasma generators are arranged in the circumferential direction, (1) the cost increases due to the multiple plasma generators, and (2) the same number of pipes for supplying raw material gas (also called "fuel gas") and cooling water, and wiring for supplying power are required, which can complicate the design and installation, or restrict the placement location.

[0008] An object of the present invention is to provide a vacuum exhaust device that is low cost and has excellent cleaning effects. [Means for solving the problem]

[0009] In order to achieve the above object, the vacuum exhaust device according to the present invention comprises: A vacuum exhaust device equipped with a plasma generator, The plasma generating device an annular flow path formed in the conductive portion; a raw material gas inlet portion disposed in the annular flow path; a radical discharge port portion disposed in the annular flow path; a power supply disposed in the annular flow path; an insulating portion that electrically insulates the annular flow path, The vacuum exhaust device is characterized in that radicals can be supplied to the inside from the radical outlet portion. [Effects of the Invention]

[0010] According to the above invention, it is possible to provide a vacuum exhaust device that is low cost and has excellent cleaning effects. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is an explanatory diagram schematically illustrating the configuration of a vacuum exhaust device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a circuit diagram of an amplifier circuit. [Figure 3] 10 is a time chart showing control when a current command value is larger than a detection value. [Figure 4]10 is a time chart showing control when a current command value is smaller than a detection value. [Figure 5] 1. (a) is an enlarged view showing the area indicated by the frame A in FIG. 1, and (b) is an enlarged view showing the area indicated by the frame B in FIG. [Figure 6] FIG. 10 is an explanatory diagram illustrating a schematic structure of the plasma generating device when it is traversed in the radial direction. [Figure 7] FIG. 4 is an explanatory diagram showing a pipeline resistance portion. [Figure 8] 1A is a longitudinal cross-sectional view of a conventional turbomolecular pump, and FIG. 1B is a cross-sectional view of the connection between the inlet pipe (216) and the outer cylinder (127). DETAILED DESCRIPTION OF THE INVENTION

[0012] <Basic Configuration of Vacuum Exhaust Apparatus 100A According to the Embodiment> 1 shows a vacuum exhaust apparatus 100A according to a first embodiment of the present invention. The vacuum exhaust apparatus includes a vacuum pump (here, a turbomolecular pump 100). This turbomolecular pump 100 is adapted to be connected to a vacuum chamber (not shown) of a target device such as a semiconductor manufacturing device.

[0013] A longitudinal cross-sectional view of this turbomolecular pump 100 is shown in Fig. 1. In Fig. 1, the turbomolecular pump 100 has an intake port 101 formed at the upper end of a cylindrical outer cylinder 127. Inside the outer cylinder 127 is provided a rotor 103 having a plurality of rotors 102 (102a, 102b, 102c, ...) which are turbine blades for sucking in and exhausting gas, formed radially and in multiple stages around its periphery. A rotor shaft 113 is attached to the center of this rotor 103, and this rotor shaft 113 is levitated and supported in the air and its position is controlled by, for example, a five-axis controlled magnetic bearing.

[0014] 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 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.

[0015] 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.

[0016] The rotor shaft 113 is made of a high magnetic permeability material (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. 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.

[0017] 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.

[0018] In the control device 200, a compensation circuit having, for example, a PID adjustment function generates excitation control command signals for the axial electromagnet 106A and the axial electromagnet 106B based on the axial position signal detected by the axial sensor 109, and the amplifier circuit 150 controls the excitation of the axial electromagnet 106A and the axial electromagnet 106B based on these excitation control command signals, so that the axial electromagnet 106A attracts the metal disc 111 upward by magnetic force, and the axial electromagnet 106B attracts the metal disc 111 downward, thereby adjusting the axial position of the rotor shaft 113.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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 through collision.

[0023] 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 rows of 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 rows of fixed blade spacers 125 (125a, 125b, 125c, etc.).

[0024] 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 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) side and is transferred to the base portion 129 is sent to the exhaust port 133.

[0025] Furthermore, depending on the application of the turbomolecular pump 100, a screw stator 131 is disposed inside the base portion 129. The screw stator 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 blades 102 (102a, 102b, 102c, etc.) of the rotor 103 are formed. The outer circumferential surface of this rotor lower cylindrical portion 103b is cylindrical and protrudes toward the inner circumferential surface of the screw stator 131, and is adjacent to the inner circumferential surface of the screw stator 131 with a predetermined gap therebetween. The exhaust gas transferred to the thread grooves 131a by the rotor 102 and the fixed blades 123 is guided along the thread grooves 131a and sent to the base portion 129. In this way, the screw stator 131 and the rotor lower cylindrical portion 103b facing it constitute a Holweck type exhaust mechanism portion 204. The Holweck type exhaust mechanism portion 204 gives directionality to the exhaust gas by the rotation of the rotor lower cylindrical portion 103b relative to the screw stator 131, thereby improving the exhaust characteristics of the turbomolecular pump 100.

[0026] 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.

[0027] In this configuration, when the rotor 102 is rotated 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.

[0028] 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.

[0029] In the above description, the screw stator 131 is disposed on the outer periphery of the rotor lower cylindrical portion 103b of the rotor 103, and the screw grooves 131a are formed on the inner circumferential surface of the screw stator 131. However, conversely, there are also cases where a screw groove is formed on the outer circumferential surface of the rotor lower cylindrical portion 103b, and a spacer having a cylindrical inner circumferential surface is arranged around it.

[0030] Depending on the application of the turbomolecular pump 100, the electrical equipment section may be surrounded 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 purge gas.

[0031] In this case, a purge gas port 132 is provided in the base portion 129, and purge gas is introduced through this piping. The introduced purge gas is sent to an exhaust port 133 through gaps 134 between the protective bearing 120 and the rotor shaft 113, between the rotor and stator of the motor 121, and between the inner cylindrical portion of the rotor blades 102 (lower cylindrical portion 103b of the rotor) and the stator column 122 or the base portion 129.

[0032] Here, the turbomolecular pump 100 requires control based on specific parameters (e.g., various characteristics corresponding to the model) that have been individually adjusted and identified for the model. To store these control parameters, the turbomolecular pump 100 is provided with an electronic circuit section 141 within its 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 lid 145.

[0033] 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 port 101 and highest at the outlet port 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 port 101 to the outlet port 133, the process gas solidifies and adheres to and accumulates inside the turbomolecular pump 100.

[0034] For example, when SiCl4 is used as the process gas in an Al etching system, the low vacuum (760 [torr] to 10 -2The vapor pressure curve shows that at low pressures (approximately 20°C) and pressures of 100[torr], solid products (e.g., AlCl3) precipitate and adhere to and accumulate inside the turbomolecular pump 100. When process gas deposits accumulate inside the turbomolecular pump 100, these deposits narrow the pump flow path, causing a decrease in the performance of the turbomolecular pump 100. The aforementioned products tend to solidify and adhere to high-pressure areas near the exhaust port 133 and the screw stator 131.

[0035] Therefore, in order to solve this problem, conventionally, a heater (not shown) or a circular water-cooled pipe 149 is wound around the outer periphery of the base portion 129, etc., and a temperature sensor (e.g., a thermistor) (not shown) is embedded in the base portion 129, and heating by the heater and 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 this embodiment, the screw stator 131 is heated by a heater (not shown) embedded in the screw stator 131, and the base portion 129 is cooled by the water-cooled pipe 149 embedded in the bottom cover 145.

[0036] Next, regarding the turbomolecular pump 100 configured as described above, we will explain the amplifier circuit 150 that controls excitation of the upper radial electromagnets 104, the lower radial electromagnets 105, and the axial electromagnets 106A and 106B. A circuit diagram of this amplifier circuit is shown in Figure 2.

[0037] 2, one end of the electromagnet winding 151 constituting the upper radial electromagnet 104 etc. is connected to a positive electrode 171a of a power supply 171 via a transistor 161, and the other end is connected to a 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.

[0038] 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.

[0039] Meanwhile, current regeneration diode 165 has its cathode terminal 165a connected to one end of electromagnet winding 151 and its anode terminal 165b connected to negative electrode 171b. Similarly, current regeneration diode 166 has its cathode terminal 166a connected to positive electrode 171a and its anode terminal 166b connected to the other end of electromagnet winding 151 via current detection circuit 181. Current detection circuit 181 is configured, for example, with a Hall sensor type current sensor or an electrical resistance element.

[0040] The amplifier circuit 150 configured as 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.

[0041] 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.

[0042] 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 size of the pulse width (pulse width times Tp1 and Tp2) to be generated within a control cycle Ts, which is one period under 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.

[0043] It is necessary to control the position of 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 power supply 171 so that the current flowing through electromagnet winding 151 can be rapidly increased (or decreased). In addition, a capacitor (not shown) is usually connected between positive electrode 171a and negative electrode 171b of power supply 171 to stabilize power supply 171.

[0044] In this configuration, when both 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.

[0045] 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.

[0046] 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 pulse width time Tp1 only once in a control cycle Ts (for example, 100 μs), as shown in Fig. 3. Therefore, during this period, the electromagnet current iL 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.

[0047] 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 pole 171b to the positive pole 171a via diodes 165 and 166.

[0048] 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.

[0049] 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 (back pump) or the like (not shown). The turbomolecular pump 100 can be used in an inverted, horizontal, or inclined position in addition to the vertical position shown in FIG.

[0050] In the turbomolecular pump 100, the aforementioned outer cylinder 127 and base portion 129 are combined to form a single case. Hereinafter, the outer cylinder 127 and base portion 129 may be collectively referred to as the "casing" or the "main body casing." Alternatively, only the outer cylinder 127 or only the base portion 129 may be referred to as the "casing." 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.

[0051] The internal configuration of the main body casing of the turbomolecular pump 100 (here, a combination of the outer cylinder 127 and the base portion 129) can be divided into a rotation mechanism portion 136 that rotates the rotor shaft 113 and the like by the motor 121, and an exhaust mechanism portion 137 that is rotationally driven by the rotation mechanism portion 136. The exhaust mechanism portion 137 can also be divided into a turbomolecular pump mechanism portion 138 that is composed of the rotor blades 102, the fixed blades 123, and the like, and a thread groove pump mechanism portion (Hollweck type exhaust mechanism portion 204) that is composed of the rotor lower cylindrical portion 103b, the screw stator 131, and the like.

[0052] The aforementioned 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.

[0053] For example, the aforementioned purge gas port 132 extending linearly in the radial direction is provided at a predetermined position (such as a position 90 degrees or 120 degrees away from the exhaust port 133) of the base portion 129. Then, purge gas is supplied to this purge gas port 132 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).

[0054] The aforementioned protective bearings 120 are also called "touchdown (T / D) bearings" or "backup bearings." These protective bearings 120 prevent the position or attitude of the rotor shaft 113 from changing significantly, even in the unlikely event of a problem with the electrical system or atmospheric inrush, and prevent damage to the rotor blades 102 and their surrounding areas.

[0055] 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.

[0056] <Plasma generator> As described above, products may accumulate inside the turbomolecular pump 100. In this embodiment, the products are washed away using a plasma generating device 210 as shown in FIGS.

[0057] Figure 5(a) shows an enlarged view of the part enclosed by frame A in Figure 1, and Figure 5(b) shows an enlarged view of the part enclosed by frame B in Figure 1. Figures 5(a) and (b) show cross sections of one plasma generation device 210 at positions 180 degrees apart.

[0058] As shown in Fig. 5(a), the plasma generator 210 includes a cover 212, a fuel gas supply port 214, a cathode electrode 216, a first insulating portion 218, and a second insulating portion 220. The "fuel gas" here means the same as the "raw material gas." As shown in Fig. 5(b), the plasma generator 210 also includes a connector 222, a cooling water inlet 224, and a cooling water outlet (not shown).

[0059] 5(a) and (b), the cover part 212 is formed in an annular (or cylindrical) shape with an L-shaped cross section. The cover part 212 is fixed to the base part 129 in an orientation such that the relatively open side faces the upper side (the side of the intake port 101) in FIGS. 1 and 5(a) and (b) and a space is formed between the cover part 212 and the base part 129.

[0060] 5(a) and 5(b), holes (holes 212a, 212b) and notches (notch 212c) extending in the radial direction of the turbomolecular pump 100 are formed on the side and bottom surfaces of the cover portion 212. The holes 212a, 212b and the notch 212c function as relief portions to prevent interference with the fuel gas supply port portion 214, the connector 222, and the cooling water inlet portion 224 (the same applies to the cooling water outlet portion, not shown), which are fixed to the cathode electrode portion 216.

[0061] As shown in Figure 5(a), the fuel gas supply port 214 is formed in a stepped cylindrical shape (or a stepped and perforated cylindrical shape) and is connected to the cathode electrode part 216 inside the cover part 212. As shown schematically in Figure 7, a fuel gas flow path 214a is formed in the fuel gas supply port 214, penetrating in the axial direction. The axial direction of the fuel gas supply port 214 is the radial direction of the turbomolecular pump 100, which is the left-right direction in Figure 5(a).

[0062] Inside the cover 212, the fuel gas supply port 214 is connected to the cathode electrode 216. The fuel gas supply port 214 is fixed to the cathode electrode 216 using, for example, a bolt and nut fastening structure. In FIG. 5(a), reference numerals 226, 227, and 228 denote O-rings that provide an airtight seal between the components. Hatching is omitted for these O-rings 226, 227, and 228.

[0063] A fuel gas supply pipe (not shown) is connected to the fuel gas supply port 214 from the outside of the cover part 212. As shown by arrow C, fuel gas is supplied to the fuel gas supply port 214 via the fuel gas supply pipe (not shown), and the fuel gas is introduced from the outside to the inside of the cover part 212. For example, gas such as NF3 (nitrogen trifluoride) or CF4 (tetrafluoromethane) is used as the fuel gas.

[0064] The cathode electrode part 216 is formed by processing a conductive material into a ring shape. The cross section of the cathode electrode part 216 is rectangular, and inside the cathode electrode part 216, a ring-shaped plasma generation chamber 230 and a similarly ring-shaped cooling water flow path 232 are formed.

[0065] The plasma generation chamber 230 is a space with a rectangular cross section, and is formed around the entire circumference of the cathode electrode part 216. The tip of the fuel gas supply port part 214 protrudes slightly into the plasma generation chamber 230, and fuel gas is introduced from the fuel gas supply port part 214 so as to be distributed throughout the entire plasma generation chamber 230. At this time, the plasma generation chamber 230 is in a vacuum state, and this vacuum state is maintained by an O-ring 227 around the second insulating part 220. To create a vacuum inside the plasma generation chamber 230, the negative pressure inside the case of the turbomolecular pump 100 (here, the combination of the outer cylinder 127 and the base part 129) can be used.

[0066] The number of fuel gas supply ports 214 may be one or more. For example, Fig. 6 shows an example in which a plurality of fuel gas supply ports 214 (here, three) are arranged in the circumferential direction of the plasma generation chamber 230. In the example of Fig. 6, the fuel gas supply ports 214 are arranged at equal intervals (here, at 120-degree intervals) in the circumferential direction of the plasma generation device 210.

[0067] By doing so, the fuel gas can be easily distributed throughout the plasma generation chamber 230, as shown by arrow C, without having to set parameters such as the pressure and inflow rate of the fuel gas very high. Furthermore, it is no longer necessary to make the fuel gas go around to a distant position (e.g., a position 180 degrees away) in the annular plasma generation chamber 230, making it easier to homogenize the density of radicals. These effects become more pronounced as the number of fuel gas supply ports 214 increases and the intervals (phase, arrangement angle) between the fuel gas supply ports 214 are reduced.

[0068] 7, a conduit resistance section 250 can be provided in the fuel gas flow path 214a of the fuel gas supply port section 214. The conduit resistance section 250 appropriately sets the flow rate of the fuel gas supplied at a predetermined pressure, for example. The pressure of the fuel gas can be set by a regulator (not shown) in the upstream stage of the vacuum exhaust device 100A.

[0069] Specifically, an orifice portion or a portion (filled portion) made of a porous material can be used as the conduit resistance portion 250, and the fuel gas can be passed through the conduit resistance portion 250. The conduit resistance portion 250 acts as a resistance to the fuel gas passing through it. Then, by selecting (designing) appropriate parameters for the conduit resistance portion 250, it becomes possible to automatically adjust the flow rate of the fuel gas supplied at a predetermined pressure (for example, 0.1 MPa) to a desired value.

[0070] Next, a first insulating part 218 and a second insulating part 220 are fitted into the cathode electrode part 216 from the outside (the top and bottom sides in FIG. 5(a)). The first insulating part 218 and the second insulating part 220 are formed using an electrically insulating material. The first insulating part 218 partially fits into the lower part of the cathode electrode part 216 in FIG. 5(a) (the side of the exhaust port 133) and the cover part 212, and slightly fits into and engages with the cathode electrode part 216 and the cover part 212.

[0071] The first insulating portion 218 supports the cathode electrode portion 216 in a state where it is spaced apart from the cover portion 212. The first insulating portion 218 functions as a spacer between the cathode electrode portion 216 and the cover portion 212. Here, it is possible to provide a plurality of first insulating portions 218 (for example, two to four), and to arrange them intermittently at equal intervals along the cathode electrode portion 216 and the cover portion 212. Furthermore, without being limited to this, the first insulating portion 218 may be formed in a continuous 360-degree ring shape along the cathode electrode portion 216 and the cover portion 212.

[0072] 5(a) (the side of the intake port 101) of the cathode electrode part 216 and partially fits into the base part 129, and is engaged with the cathode electrode part 216 and the base part 129. The second insulating part 220 functions as a spacer that separates the cathode electrode part 216 from the base part 129.

[0073] The second insulating section 220 has a radical discharge flow path 234 inside. The radical discharge flow path 234 is spatially connected to the plasma generation chamber 230 of the cathode electrode section 216 and a radical guide path 242 (described later) formed in the base section 129. Here, in this embodiment, the second insulating section 220 functions as an insulating section that electrically insulates the radical discharge port section disposed in the annular flow path (here, the plasma generation chamber 230) from the annular flow path (here, the plasma generation chamber 230).

[0074] The second insulating section 220 can be formed, for example, in a stepped cylindrical shape extending in the vertical direction in FIG. 5(a) (parallel to the axial direction of the turbomolecular pump 100). Here, a plurality of second insulating sections 220 (for example, 2 to 4) can be provided and arranged at equal intervals along the cathode electrode section 216 and the cover section 212. In this case, the cross-sectional shape (flat cross-sectional shape along the radial direction (perpendicular to the axial direction)) of the radical discharge channel 234 can be a perfect circle. Note that the cross-sectional shape (vertical cross-sectional shape along the axial direction (perpendicular to the radial direction)) of the radical discharge channel 234 can also be a tapered shape with a varying hole diameter or a stepped shape.

[0075] The second insulating part 220 may also be formed in a 360-degree continuous ring shape along the circumferential direction of the cathode electrode part 216 and the cover part 212. In this case, it is possible to form multiple radical discharge channels 234 in a single second insulating part 220. It is also possible to form the second insulating part 220 in a shape that extends in an arc shape along the circumferential direction of the cathode electrode part 216. In this case, it is possible to form one or multiple radical discharge channels 234 in a single arc-shaped second insulating part 220.

[0076] As shown in Fig. 5(b), a connector 222 is electrically connected to the cathode electrode section 216. The connector 222 is inserted into the cathode electrode section 216 from the outside of the cover section 212, and an electrode pin 236 reaches the cathode electrode section 216. The connector 222 is connected to a power supply section 238 shown schematically in Fig. 1, and functions as a cathode electrode (here, a negative electrode) into which current flows (electrons flow out).

[0077] 1, the power supply unit 238 is also electrically connected to the case (the combination of the outer cylinder 127 and base portion 129 described above) of the turbomolecular pump 100. The case (here, the outer cylinder 127 or the base portion 129) is grounded and functions as an anode electrode (here, a positive electrode, + pole) from which current flows out (electrons flow in). The part (here, the outer cylinder 127 or the base portion 129) that functions as an anode electrode can be referred to as, for example, an "anode electrode portion."

[0078] By connecting the power supply unit 238 in this manner, the plasma generation chamber 230 of the cathode electrode unit 216 becomes the negative electrode (-electrode), and the case (here, the outer cylinder 127 or the base unit 129) that constitutes the outer wall of the turbomolecular pump 100 becomes the positive electrode (+electrode).

[0079] The power supply unit 238 applies a high voltage to atoms of the fuel gas introduced from the cathode electrode unit 216 into the plasma generation chamber 230, generating radicals. Since the plasma generation chamber 230 is in a vacuum state and is formed around the entire circumference of the cathode electrode unit 216, radicals are generated all around the circumference of the cathode electrode unit 216. The radicals flow into a radical guide path 242 formed in the base unit 129, as shown by arrow D in FIG. 5(a).

[0080] The radical guide path 242 reaches the screw stator 131 and is connected to a radical introduction path 244 formed in the screw stator 131. The radical introduction path 244 opens to face the screw groove 131a. This opening serves as a radical introduction port 244a. In this way, the radical discharge flow path 234 is spatially connected to the screw groove 131a via the radical guide path 242 and the radical introduction path 244.

[0081] The radicals generated in the plasma generation chamber 230 are introduced into the thread groove 131a through the radical discharge flow path 234, the radical guide path 242, and the radical introduction path 244. The radicals introduced into the thread groove 131a are used to clean the thread groove pump mechanism (Hollweck type exhaust mechanism 204) and its surroundings.

[0082] In this embodiment, as described above, the thread groove pump mechanism is configured by the Holweck-type exhaust mechanism 204. A plurality of helical thread grooves 131a are formed on the inner peripheral surface of the screw stator 131 that configures the Holweck-type exhaust mechanism 204. Furthermore, the thread grooves 131a are connected to the radical discharge flow path 234 via the radical guide path 242 and the radical introduction path 244.

[0083] For this reason, it is conceivable to provide a plurality of openings (radical introduction ports 244a) facing the thread grooves 131a of the screw stator 131, and to provide one or more radical introduction ports 244a for the multiple thread grooves 131a. By doing so, it becomes possible to efficiently introduce radicals into the multiple thread grooves 131a.

[0084] Specifically, the number of radical introduction ports 244a may be a divisor of the number (number of threads) of the multiple thread grooves 131a. For example, if the number of threads of the thread groove 131a is "12," one radical introduction port 244a may be provided every six threads (or every four threads or every three threads), for a total of two (or three or four) radical introduction ports 244a. Furthermore, one radical introduction port 244a may be provided for every 12 threads, for a total of 12 radical introduction ports 244a. By doing so, it becomes possible to more evenly supply radicals to the multiple thread grooves 131a.

[0085] The number of radical introduction ports 244a may be a multiple of the number (number of threads) of the multiple thread grooves 131a. For example, if the number of threads in the thread groove 131a is "3," three (or another number) radical introduction ports 244a may be provided in each thread at equal phases (120-degree intervals), making the total number of radical introduction ports 244a nine (or another multiple of four). This also makes it possible to supply radicals more evenly and over a wider range (the entire thread groove 131a) to the multiple thread grooves 131a. Here, the arrangement (phase and number) of the radical introduction ports 244a in one thread groove 131a may be, for example, 180 degrees (two ports), 120 degrees (three ports), 90 degrees (four ports), 45 degrees (eight ports), or 30 degrees (12 ports).

[0086] For example, one radical inlet 244a may be connected to one radical discharge channel 234, one radical guide channel 242, and one radical inlet 244. In this case, radicals are supplied from one radical discharge channel 234 to one radical inlet 244a.

[0087] Also, for example, one (or one) radical guide path 242 can be branched midway and connected to a plurality of radical introduction paths 244 (including the radical introduction ports 244a). In this case, the number of radical discharge paths 234 can be made smaller than the number of radical introduction ports 244a.

[0088] Next, the supply of cooling water will be described. As shown in Fig. 5(b), the aforementioned cooling water inlet portion 224 is formed in a stepped cylindrical shape (or a stepped and perforated cylindrical shape). The cooling water inlet portion 224 is connected to the cathode electrode portion 216 inside the cover portion 212. Although not shown, a cooling water flow path is formed in the cooling water inlet portion 224 that penetrates in the axial direction. The axial direction of the cooling water inlet portion 224 is the axial direction of the turbomolecular pump 100, which is the up-and-down direction in Fig. 5(b).

[0089] The cooling water inlet 224 is connected to the cathode electrode 216 inside the cover 212. The cooling water inlet 224 is fixed to the cathode electrode 216 using, for example, a bolt and nut connection structure.

[0090] Although not shown, a cooling water pipe is connected to the cooling water inlet 224 from the outside of the cover 212, and a cooling water pump and a cooling water supply source (for example, a cooling water tank) are connected to this cooling water pipe. Note that a cooling water outlet, not shown, is also formed in the same manner as the cooling water inlet 224, and is connected to the cooling water pump via a cooling water pipe.

[0091] Cooling water is supplied to the cooling water inlet 224 via a cooling water pipe as indicated by arrow E. The cooling water is introduced from the cooling water inlet 224 into an annular cooling water flow path 232 and cools the entire cathode electrode part 216. The cooling water that flows through the cooling water flow path 232 passes through a cooling water outlet (not shown) and circulates between the cooling water flow path 232 and the turbo molecular pump 100.

[0092] <Representative Advantages of the Vacuum Exhaust Device 100A According to the Present Embodiment> A vacuum exhaust apparatus 100A equipped with the above-described plasma generator 210 will be described below in comparison with the conventional technology shown in Figures 8(a) and (b). In Figures 8(a) and (b), the same parts as those in the vacuum exhaust apparatus 100A of the embodiment shown in Figures 1 to 7 are designated by the same reference numerals. Figure 8(a) shows a turbomolecular pump 600 (vacuum exhaust apparatus) of the conventional example.

[0093] In this conventional turbomolecular pump 600, a plurality of (here, two) plasma generators 610 are connected to the outer cylinder 127 via valve devices 614 and introduction pipes 616. This is similar to the invention disclosed in Patent Document 1 mentioned above.

[0094] However, plasma generator 610 is disposed near exhaust port 133, where deposits are likely to occur, and near screw stator 131. Furthermore, radicals are introduced into annular groove 632 and then into screw groove 131a through circumferentially arranged communication ports 654. These advantages, compared to the invention disclosed in Patent Document 1, include the elimination of the need for a design that partially widens the gap between rotor 102 and stator 123 and the ability to supply radicals from a position closer to the deposits.

[0095] 1 to 7, the plasma generator 210 is provided in a position close to the exhaust port 133 and the screw stator 131 where deposits are likely to occur. Furthermore, in the vacuum exhaust device 100A of this embodiment, the plasma generator 210 has an annular cathode electrode portion 216.

[0096] The cathode electrode part 216 is provided at a position sandwiched between the cover part 212 and the base part 129, and applies a voltage to the fuel gas in the plasma generation chamber 230. The cathode electrode part 216 is combined with the turbo molecular pump 100 so as not to protrude as much as possible, and the vacuum exhaust device 100A is made smaller than the conventional technology shown in Figures 8(a) and (b).

[0097] Therefore, according to the vacuum exhaust device 100A of this embodiment, compared to the conventional technology shown in FIGS. 8(a) and 8(b), it is possible to place the electrode (here, the cathode electrode portion 216) of the plasma generator 210 closer to the position where deposits are likely to occur. This makes it possible to more reliably supply radicals to deposits before they are deactivated. As a result, it is possible to improve the cleaning effect compared to the conventional technology shown in FIGS. 8(a) and 8(b).

[0098] Furthermore, according to the vacuum exhaust device 100A of the embodiment, the cathode electrode section 216 is formed in an annular shape, and a voltage is applied in the circumferential direction by one cathode electrode section 216. Therefore, the piping and wiring related to the supply of radicals can be consolidated, and the costs of the materials and work for the wiring and piping can be reduced. Furthermore, the space required for the wiring and piping can be minimized. Furthermore, the structure of the plasma generator 210 can be simplified, and the plasma generator 210 can be made smaller. These factors make it possible to reduce the manufacturing cost of the vacuum exhaust device 100A. Furthermore, it becomes possible to increase the degree of freedom in installing the vacuum exhaust device 100A.

[0099] Furthermore, for example, if the same installation space as before can be secured, the turbomolecular pump 100 can be made larger (larger capacity), and the plasma generator 210 can be made larger in accordance with the larger size of the turbomolecular pump 100.

[0100] Furthermore, since the cathode electrode part 216 is provided with the cooling water flow path 232, it is possible to directly cool the cathode electrode part 216. This makes it possible to effectively prevent the cathode electrode part 216 from overheating, and makes it easier to improve the output of the plasma generator 210.

[0101] Furthermore, the number of radical inlet ports 244a is a divisor of the number of threads of the screw groove 131a in the screw groove pump mechanism (here, the Holweck-type exhaust mechanism 204). This allows radicals to be introduced at regular intervals, enabling a uniform supply of radicals. This also reduces (or prevents) unevenness (spots, bias) in the radical density in the screw groove pump mechanism (here, the Holweck-type exhaust mechanism 204).

[0102] Furthermore, even when the number of radical inlets 244a is set to a multiple of the number of threads of the screw groove 131a in the screw groove pump mechanism (here, the Holweck-type exhaust mechanism 204), it is possible to uniformly supply radicals. This also makes it possible to reduce (or prevent) unevenness (spots, bias) in the density of radicals in the screw groove pump mechanism (here, the Holweck-type exhaust mechanism 204).

[0103] Furthermore, as in the example of FIG. 6, multiple (e.g., three) fuel gas supply ports 214 are arranged in the circumferential direction of the plasma generation chamber 230, thereby reducing (or preventing) unevenness in the density of the fuel gas within the plasma generation device 210.

[0104] Furthermore, the second insulating section 220 having the radical discharge flow path 234 can be disposed at any position in the circumferential direction of the cathode electrode section 216. Therefore, the number of radical discharge flow paths 234 can also be set arbitrarily within the range of the circumferential length of the cathode electrode section 216.

[0105] 7, the fuel gas supply port 214 is provided with a conduit resistance section 250 having a predetermined conduit resistance, so that the flow rate of the fuel gas can be adjusted by supplying the fuel gas at a constant pressure, and a flow meter or a flow rate control valve is not required.

[0106] Furthermore, since power is supplied from the power supply unit 238 with the annular cathode electrode unit 216 as the negative electrode and the case of the turbomolecular pump 100 (here, the outer cylinder 127 or the base unit 129) as the positive electrode, plasma can be generated with electrons confined within the tubular space (here, the plasma generation chamber 230). Furthermore, radicals can be supplied effectively without increasing the size of the plasma generator 210.

[0107] Furthermore, in this embodiment, the vacuum exhaust device 100A is configured by combining the turbomolecular pump 100 and the plasma generator 210, but this is not limiting, and for example, the plasma generator 210 can be a device that configures a part of the turbomolecular pump 100. In this case, the turbomolecular pump 100 equipped with the plasma generator 210 is configured.

[0108] <Inventions that can be extracted from the embodiments> The following inventions can be extracted from the above-described embodiments. (1) A vacuum exhaust device (such as the vacuum exhaust device 100A) equipped with a plasma generator (such as the plasma generator 210), The plasma generating device An annular flow path (such as the plasma generation chamber 230) formed in a conductive portion (such as the cathode electrode portion 216), a raw material gas inlet portion (such as a fuel gas supply port portion 214) disposed in the annular flow path; a radical discharge port portion (such as the second insulating portion 220) disposed in the annular flow path; a power supply (such as a connector 222) disposed in the annular flow path; and an insulating portion (a first insulating portion 218, a second insulating portion 220, etc.) that electrically insulates the annular flow path, The vacuum exhaust device is characterized in that radicals can be supplied from the radical outlet portion to the inside (such as the inside of a combined case of the outer cylinder 127 and the base portion 129). (2) The vacuum exhaust device according to claim 1, wherein the conductive portion includes a cooling flow path (such as a cooling water flow path 232) that does not communicate with the annular flow path. (3) The vacuum exhaust device has a thread groove pump unit (such as a Holweck type exhaust mechanism unit 204, which is a thread groove pump mechanism unit), The vacuum exhaust device according to claim 1, characterized in that the number of the radical discharge port sections is a divisor (such as "12," "6," "4," "3," "2," or "1") of the number of thread grooves (such as 12) of the thread groove pump section. (4) The vacuum exhaust device has a thread groove pump unit, 2. The vacuum exhaust device according to claim 1, wherein the number of the radical discharge port sections is a multiple (e.g., "3," "6," "9," "12," etc.) of the number of thread grooves (e.g., 3) of the thread groove pump section. (5) The vacuum exhaust device according to claim 1, wherein a plurality of the raw material gas inlet ports are arranged in the circumferential direction of the annular flow path. (6) The vacuum exhaust device according to claim 1, wherein a conduit resistance section (such as conduit resistance section 250) having a predetermined conduit resistance is provided at the source gas inlet section. (7) The vacuum exhaust device according to claim 1, wherein the power supply unit is connected so that the annular flow path serves as a negative electrode and the outer wall of the vacuum exhaust device serves as a positive electrode.

[0109] <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 spirit of the present invention. As the screw groove pump section, a Holweck type exhaust mechanism (Holbeck type exhaust mechanism section 204) in which the screw stator 131 is cylindrical and has a spiral screw groove on its inner peripheral surface has been described as an example. However, for example, a Sigburn type exhaust mechanism in which the screw stator 131 is disk-shaped and has spiral screw grooves on its upper and lower surfaces may also be used. [Explanation of symbols]

[0110] 100A: Vacuum exhaust device 100: Turbomolecular pump 102: Rotor 103: Rotating body 127: Outer cylinder 129: Base 131: Screw stator 136: Rotation mechanism 137: Exhaust mechanism 138: Turbomolecular pump mechanism 204: Holweck type exhaust mechanism 210: Plasma generator 200: Control device 214: Fuel gas supply port 214a: fuel gas flow path 216: Cathode electrode part 218: First insulating part 220: Second insulating part 222: Connector 224: Cooling water inlet 230: Plasma generation chamber 232: Cooling water flow path 234: Radical discharge channel 238: Power supply section 242: Radical Guideway 244: Radical introduction path 244a: Radical inlet 250: Pipe resistance section

Claims

1. A vacuum exhaust device equipped with a plasma generator, The plasma generating device an annular flow path formed in the conductive portion; a raw material gas inlet portion disposed in the annular flow path; a radical discharge port portion disposed in the annular flow path; a power supply disposed in the annular flow path; an insulating portion that electrically insulates the annular flow path, A vacuum exhaust device capable of supplying radicals to the inside from the radical outlet portion.

2. 2. The vacuum exhaust system according to claim 1, wherein the conductive portion includes a cooling passage that does not communicate with the annular passage.

3. the vacuum exhaust device has a thread groove pump unit, 2. The vacuum exhaust device according to claim 1, wherein the number of the radical discharge ports is a divisor of the number of the thread grooves of the thread groove pump section.

4. the vacuum exhaust device has a thread groove pump unit, 2. The vacuum exhaust device according to claim 1, wherein the number of the radical discharge ports is a multiple of the number of the thread grooves of the thread groove pump section.

5. 2. The vacuum exhaust system according to claim 1, wherein a plurality of the raw material gas inlet ports are arranged in the circumferential direction of the annular flow path.

6. 2. The vacuum exhaust system according to claim 1, wherein a conduit resistance portion having a predetermined conduit resistance is provided at the source gas inlet portion.

7. 2. The vacuum exhaust device according to claim 1, wherein the power supply unit is connected so that the annular flow path serves as a negative electrode and the outer wall of the vacuum exhaust device serves as a positive electrode.

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