Vacuum pumps and vacuum pump components

Abstract

To provide a vacuum pump that can effectively utilize radicals, and a vacuum pump component.SOLUTION: A turbo molecular pump 100 comprises a turbo molecular pump mechanism part 138 including a rotor 103 capable of freely rotating, and fixed blades 123 combined with the rotor, and an outer cylinder 127 containing the turbo molecular pump mechanism part 138, and is provided with a radical discharge promotion structure connecting a radical introduction port 218 arranged in the outer cylinder 127, and a communication port 254 arranged in the turbo molecular pump mechanism part 138.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to vacuum pumps, such as turbomolecular pumps, and vacuum pump components. [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 such as turbomolecular pumps, reaction products generated during the manufacturing process of semiconductors and the like 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, to which a plasma generator (radical supply means 201) is connected. Radicals introduced into the casing flow circumferentially in 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 a space secured 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. Therefore, in order to introduce a sufficient amount of radicals into the casing while preventing a decrease in pump performance, it is necessary to keep the size of the communication port to a minimum, prevent the gap between the rotor and the fixed blades from becoming excessive, and provide multiple communication ports in the circumferential direction of the casing to ensure the opening area of ​​the communication ports. [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] Because the pressure inside the vacuum pump is low, the inside of the vacuum pump is often in a state of molecular flow with radicals flying around randomly. In such cases, the probability of radicals flowing from the communication port into the exhaust mechanism can be calculated from the ratio of the cross-sectional area of ​​the communication port to the surface area of ​​the annular passage.

[0007] For example, if the communication port has a diameter of 12 mm (cross-sectional area (opening area) of 113 mm), 2 (≒π×12 2 / 4)) has a perfect circular shape, and the annular passage has a diameter of 300 mm and a width (for example, in Patent Document 1, the length in the axial direction of the rotor shaft 113, etc.) of 20 mm (surface area 37,699 mm 2 (=300×π×20×2)), the ratio of the cross-sectional area of ​​the communication port (which can be considered as the probability that radicals will flow from the communication port into the exhaust system) is 0.3% of the surface area of ​​the annular passage. In this case, the probability that radicals flowing through the annular passage will flow into the communication port in one go (on the first rotation after entering the annular passage) can also be considered to be 0.3%.

[0008] Furthermore, radicals that do not enter the communication port circulate around the annular passage. For example, if the ratio of the cross-sectional area of ​​the communication port to the surface area of ​​the annular passage is 0.3% as described above, then theoretically, the radicals can be thought of as circulating 333 times before finally entering the communication port. As they circulate, the radicals collide with the inner wall of the annular passage.

[0009] When simply introducing gas, repeated wall collisions do not change the gas characteristics, so a structure such as that disclosed in Patent Document 1 is acceptable. In addition, increasing the cross-sectional area of ​​the annular passage is advantageous for reducing the piping resistance of the annular passage, and as the cross-sectional area of ​​the annular passage increases, the surface area of ​​the annular passage is often increased accordingly. However, when introducing plasma, the activity of the plasma gradually decreases with repeated wall collisions. In other words, if the communication port is excessively small compared to the surface area of ​​the annular passage, radicals repeatedly collide with the wall in the annular passage, resulting in a significant loss of activity and a reduced cleaning effect.

[0010] An object of the present invention is to provide a vacuum pump and vacuum pump components that can effectively utilize radicals. [Means for solving the problem]

[0011] (1) In order to achieve the above object, the vacuum pump according to the present invention comprises: an exhaust mechanism including a rotatable rotor and a stator combined with the rotor; a casing that houses the exhaust mechanism, a radical introduction port disposed in the casing and a communication port disposed in the exhaust mechanism; spatially connected A radical discharge promoting structure is provided. 、 The radical discharge promoting structure guides the radicals from the radical introduction port to the corresponding communication port without dispersing the radicals beyond the communication port. It is characterized by: (2) In order to achieve the above object, another vacuum pump according to the present invention comprises: an exhaust mechanism including a rotatable rotor and a stator combined with the rotor; a casing that houses the exhaust mechanism, a radical exhaust promotion structure is provided that spatially connects a radical introduction port disposed in the casing and a communication port disposed in the exhaust mechanism; the radical exhaust promotion structure is configured by a groove provided in at least one of the casing and the exhaust mechanism, The groove is closed at a position where the radical introduction port is spatially connected to the communication port. It is characterized by: (3) In order to achieve the above object, a vacuum pump component according to the present invention comprises: an exhaust mechanism including a rotatable rotor and a stator combined with the rotor; a casing that houses the exhaust mechanism, a radical introduction port disposed in the casing; ,before a communication port disposed in the exhaust mechanism; , spatially connecting A radical discharge promoting structure is provided. 、 The radical discharge promoting structure guides the radicals from the radical introduction port to the corresponding communication port without dispersing the radicals beyond the communication port. It is characterized by: [Effects of the Invention]

[0012] According to the above invention, it is possible to provide a vacuum pump and vacuum pump components that can effectively utilize radicals. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is an explanatory diagram schematically illustrating the configuration of a turbomolecular pump (100) according to a first 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] FIG. 1(a) is an explanatory diagram showing a longitudinal section of the turbomolecular pump (100) according to the first embodiment, and FIG. 1(b) is an explanatory diagram showing a cross section of the connection between the inlet pipe (216) and the outer cylinder (127). [Figure 6] FIG. 10 is an explanatory diagram showing the positional relationship of a plurality of inlet pipes (216). [Figure 7] 5(a) is an enlarged view showing the connection between the inlet pipe (216) and the outer cylinder (127) of the turbomolecular pump (100) according to the first embodiment, (b) is an enlarged view showing the communication port (254) and its surroundings in FIG. 5(a), and (c) is an enlarged view of FIG. 5(b). [Figure 8] (a1) is an explanatory diagram showing a tapered pipe shape having a radical exhaust promotion structure, (a2) is an explanatory diagram showing a curved pipe shape having a radical exhaust promotion structure, (b1) is an explanatory diagram showing a stepped pipe shape of a conventional structure, and (b2) is an explanatory diagram showing a branched pipe shape of a conventional structure. [Figure 9] 10A is a longitudinal cross-sectional view of a turbomolecular pump (400) according to a second embodiment, and FIG. 10B is a cross-sectional view of a connection between an inlet pipe (216) and an outer cylinder (127). [Figure 10] FIG. 10 is an explanatory view showing a longitudinal section of a turbomolecular pump (500) according to a third embodiment. [Figure 11] 1A is a longitudinal cross-sectional view of a conventional turbomolecular pump (600), and FIG. 1B is a cross-sectional view of a connection between an inlet pipe (216) and an outer cylinder (127). DETAILED DESCRIPTION OF THE INVENTION

[0014] <Basic Configuration of the Turbomolecular Pump 100 According to the First Embodiment> 1 shows a turbomolecular pump 100 as a vacuum pump according to a first embodiment of the present invention. 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.).

[0026] 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.

[0027] 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, etc.) of the rotor 103 are formed. The outer peripheral surface of the rotor lower cylindrical portion 103b is cylindrical and projects 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 the 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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 formed on the inner circumferential surface of the threaded spacer 131. However, conversely, there are also cases where a thread 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 disposed around it.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] For example, when SiCl4 is used as the process gas in an Al etching system, the low vacuum (760 [torr] to 10 -2 The vapor pressure curve shows that at temperatures of 100[torr]) and low temperatures (approximately 20[°C]), 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 are prone to solidification and adhesion in high-pressure areas near the exhaust port 133 and near the threaded spacer 131.

[0037] 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 threaded spacer 131 is heated by a heater (not shown) embedded in the threaded spacer 131, and the base portion 129 is cooled by the water-cooled pipe 149 embedded in the bottom cover 145.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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 threaded spacer 131, and the like.

[0054] 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.

[0055] 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).

[0056] 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.

[0057] 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.

[0058] <Configuration of radical flow path> As described above, products may accumulate inside the turbomolecular pump 100. In the first embodiment, the products are cleaned using a plasma generation device 210 as shown in Figures 1 and 5(a).

[0059] The plasma generator 210 is provided with electrodes (not shown) and the like inside a cylinder 212. The plasma generator 210 applies a high voltage to atoms of a raw material gas introduced from the outside into the cylinder 212 to generate radicals. Gases such as NF3 (nitrogen trifluoride) and CF4 (tetrafluoromethane) are used as the raw material gas.

[0060] The plasma generator 210 is connected to the outer cylinder 127 of the turbomolecular pump 100 via a valve device 214 and an inlet pipe 216. Although the plasma generator 210, the valve device 214, and the inlet pipe 216 are shown separated from one another in FIGS. 1 and 5(a), they are airtightly connected via flanges. Note that at least some of the connections between the plasma generator 210, the valve device 214, and the inlet pipe 216 may be made using components such as clamps (not shown).

[0061] The introduction pipe 216 is airtightly connected to the outer casing 127. A plurality of radical introduction ports 218 (described later) are provided on the side surface of the outer casing 127. In the first embodiment, the radical introduction port 218 is a perfectly circular hole penetrating the outer casing 127. The tubular portion of the introduction pipe 216 is also formed in a perfectly circular shape. The inner circumferential surface of the introduction pipe 216 is tapered, and the inner diameter of the introduction pipe 216 gradually decreases from the plasma generator 210 side (the valve device 214 side) to the outer casing 127 side. Furthermore, the internal space of the introduction pipe 216 and the radical introduction ports 218 are spatially connected.

[0062] In the outer cylinder 127, the radical introduction ports 218 and the introduction pipes 216 are arranged at 120° intervals in the circumferential direction, as shown schematically in FIG. 6. FIG. 6 shows a state (transverse cross section, horizontal cross section) of the turbomolecular pump 100 cut in the radial direction (radial direction of the outer cylinder 127) at the position of the introduction pipe 216 connected to the radical introduction port 218. Although the plasma generator 210 and the valve device 214 are not shown in FIG. 6, a set of the plasma generator 210, the valve device 214, and the introduction pipe 216 is provided for each radical introduction port 218. In other words, in the first embodiment, three sets of the plasma generator 210, the valve device 214, and the introduction pipe 216 are provided. The cross sections of FIGS. 1 and 5(a) are taken along line AA in FIG. 6.

[0063] As shown in FIGS. 5(a) and 7(a), the introduction pipe 216 and the outer cylinder 127 are connected by abutting one flange portion 216a of the introduction pipe 216 against a seating surface 127a formed on the outer cylinder 127. FIG. 7(a) shows an enlarged view of the periphery of the radical introduction port 218 in FIG. 5(a). The flange portion 216a of the introduction pipe 216 is disposed midway along the axial direction of the introduction pipe 216. An O-ring 220 provides an airtight seal between the flange portion 216a of the introduction pipe 216 and the seating surface 127a of the outer cylinder 127. The other flange portion 216b of the introduction pipe 216 is airtightly connected to the valve device 214.

[0064] As shown in Figures 5(b) and 7(c), one axial end (end on the outer cylinder 127 side) 222 of the introduction pipe 216 enters the radical introduction port 218 of the outer cylinder 127 and protrudes inside the outer cylinder 127. Figure 5(b) shows a cross section (planar cross section) of the connection portion between the introduction pipe 216 and the outer cylinder 127 in Figure 5(a) when viewed from the upper side (the side of the intake port 101) in Figure 5(a). Figure 7(c) shows an enlarged view of Figure 5(b).

[0065] As shown in FIG. 5(a), inside the outer tube 127, an annular passage (annular groove 232) is formed around the entire circumference on the outer peripheral surface of the threaded spacer 131. As shown in FIG. 7(a), the annular groove 232 is a stepped space and has a wide opening 232a and a narrow opening 232b. The wide opening 232a is located on the outer peripheral side of the annular groove 232. The narrow opening 232b is located on the inner peripheral side of the annular groove 232 and opens to the bottom surface of the wide opening 232a (the bottom surface located on the inner peripheral side of the annular groove 232). The annular groove 232 faces the inner peripheral surface of the outer tube 127 and is defined by the threaded spacer 131 and the outer tube 127.

[0066] As shown in Figure 5(a) and Figures 7(a) and (b), an annular groove 232 is formed along the inner peripheral surface of the outer cylinder 127, and one end 222 of the introduction pipe 216 protrudes into the annular groove 232. Figure 7(b) shows an enlarged view of the annular groove 232 and its surroundings on the left side of Figure 5(a).

[0067] 5 to 7, a manifold (branched tubular part 242) constituting the radical discharge promoting structure is disposed in the annular groove part 232. As shown in Fig. 5(b) and Fig. 7(c), the branched tubular part 242 is formed in a tubular shape having one inlet end part 246, two branched outlet end parts 248a, 248b, and a main pipe part 250 connecting the inlet end part 246 and the outlet end parts 248a, 248b.

[0068] The inlet end 246 of the branch tubular part 242 is partially curved in an arc and is connected to one end 222 of the inlet pipe 216. The two outlet ends 248a, 248b of the branch tubular part 242 are also curved in an arc and extend from the wide opening 232a of the annular groove 232 into the narrow opening 232b. The main pipe portion 250 is formed in an arc shape that curves along the annular groove 232. In addition, a sharp protrusion 252 that protrudes toward the center of the radical introduction port 218 is formed at the branched portion of the two main pipe portions 250.

[0069] The two outlet ends 248a, 248b of the branch tubular part 242 are connected to a communication port 254 (shown in the left part of FIG. 5(a) and in FIG. 7(b)) provided in the threaded spacer 131. The communication port 254 opens into the bottom surface of the narrow opening 232b in the threaded spacer 131 and passes through the threaded spacer 131. The communication port 254 opens facing the thread groove 131a and spatially connects the thread groove 131a with the interior of the branch tubular part 242.

[0070] Two communication ports 254 are formed for each branch tubular part 242. In the first embodiment, a total of six (=2×3) communication ports 254 are provided around the entire circumference of the annular groove portion 232. Furthermore, the communication ports 254 are arranged symmetrically in pairs at 120-degree intervals in the circumferential direction of the annular groove portion 232. With regard to the arrangement of the two symmetric communication ports 254, the phase in the circumferential direction of the threaded spacer 131 (the same as the phase shift in the circumferential direction of the outer cylinder 127) is different from the phase shift in the circumferential direction of the outer cylinder 127 of the corresponding radical introduction port 218.

[0071] In the first embodiment, the diameters of the openings at the outlet ends 248a, 248b of the branch tubular part 242 are the same. Furthermore, the diameter (inner diameter) of the opening (e.g., a circular opening) at the introduction end 246 is larger than the diameter (inner diameter) of the opening (e.g., a circular opening) at each of the outlet ends 248a, 248b. However, without being limited to this, the diameter (inner diameter) of the opening at the introduction end 246 and the diameter (inner diameter) of the opening at each of the outlet ends 248a, 248b may be the same. Furthermore, the diameter (inner diameter) of the opening at the introduction end 246 may be smaller than the diameter (inner diameter) of the opening at each of the outlet ends 248a, 248b. Furthermore, the diameters (inner diameters) of the openings at the outlet ends 248a, 248b may be different from each other.

[0072] The connection between the inlet end 246 of the branch tubular part 242 and one end 222 of the inlet pipe 216 is made by press-fitting (e.g., press-fitting the branch tubular part 242 into the inlet pipe 216). The connection between the two outlet ends 248a, 248b of the branch tubular part 242 and the threaded spacer 131 in which the communication port 254 is formed is also made by press-fitting (e.g., press-fitting the branch tubular part 242 into the threaded spacer 131). In this way, the branch tubular part 242 connects the radical introduction port 218 disposed in the outer tube 127 to the communication port 254 disposed in the threaded spacer 131. The connection between the branch tubular part 242 and the inlet pipe 216 or the threaded spacer 131 can also be made by methods other than press-fitting (e.g., welding). However, using a connection method that involves material deformation, such as press-fitting, makes it easier to disassemble the parts than using a connection method that involves material melting, such as welding.

[0073] Radicals generated by the plasma generator 210 pass through the valve device 214, which is controlled to an open state, and the inlet pipe 216, and are introduced into the outflow branch tubular part 242 without dispersing into the annular groove 232. The radicals introduced into the branch tubular part 242 are diverted along the shape of the branch tubular part 242 and are discharged into the thread groove 131a through the outlet ends 248a and 248b and the corresponding communication ports 254. The radicals discharged into the thread groove 131a mainly clean components such as the thread groove pump mechanism (Hollweck-type exhaust mechanism 204) and the exhaust port 133. By providing the communication port 254 midway along the thread groove 131a and introducing the radicals while the rotor 102 is rotating, the radicals can be effectively directed downstream, where reaction products are deposited, without flowing into the turbomolecular pump mechanism 138.

[0074] <Radical exhaust promotion structure> As described above, the branch tubular part 242 has a radical exhaust promotion structure, and thus guides the radicals supplied to the turbomolecular pump 100 directly from the radical introduction port 218 to the communication port 254 without dispersing them within the annular groove part 232. The branch tubular part 242 is contained (accommodated) within the annular groove part 232, and the area of ​​the inner wall (inner surface) of the branch tubular part 242 is smaller than the area of ​​the inner wall (inner surface) of the annular groove part 232.

[0075] The wall surfaces with which the radicals can collide are limited to the inner wall (inner surface) of the branched tubular part 242. The radicals reach the communication opening 254 without dispersing within the annular groove 232 or colliding with the wall surface (inner surface) of the annular groove 232. As a result, the radicals can be prevented from colliding with the inner wall (inner surface) of the annular groove 232 and being deactivated. Furthermore, the radicals that do not flow into the communication opening 254 can be prevented from circling the annular groove 232 multiple times. These factors make it possible to effectively utilize the radicals.

[0076] The radical exhaust promotion structure described above will be described below in comparison with the conventional technology shown in FIGS. 11(a) and 11(b). In FIGS. 11(a) and 11(b), the same components as those in the first embodiment shown in FIGS. 1, 5(a), and 5(b), etc., are designated by the same reference numerals. FIG. 11(a) shows a conventional turbomolecular pump 600. This conventional turbomolecular pump 600 does not include the branched tubular component 242 shown in FIGS. 1, 5(a), and 5(b), etc. FIG. 11(b) shows a cross section (horizontal cross section, horizontal cross section) of the connection portion between the introduction pipe 216 and the outer cylinder 127 in FIG. 11(a) when viewed from the upper side (the side of the intake port 101) in FIG. 5(a).

[0077] 11(a) and 11(b) in the prior art, the larger the width of the radical flow path (here, the length in the axial direction of the rotor shaft 113, etc.) and the larger the cross-sectional area that can be calculated using parameters such as the width, the smaller the piping resistance and the easier it is to introduce radicals into the outer cylinder 127. Also, with regard to the communication port 254, the smaller the cross-sectional area (opening area) is relative to the surface area of ​​the annular groove 632, the more difficult it is for radicals to flow in, and the more collisions and circulations of radicals occur.

[0078] Furthermore, because the communication port 254 opens at the bottom of the thread groove 131a, the diameter and cross-sectional area of ​​the communication port 254 cannot be made larger than the width of the thread groove 131a. Therefore, as the diameter and cross-sectional area of ​​the communication port 254 increase, the width of the thread groove 131a must also increase. If the width of the thread groove 131a is increased too much, the compression of the exhaust gas is affected, resulting in a decrease in the performance of the turbomolecular pump 100. Therefore, there is an appropriate balance between the sizes of the annular groove 632 and the communication port 254, and the width of the annular groove 632 and the communication port 254 cannot be increased to the extent that this balance is disrupted. The fact that the larger the diameter and cross-sectional area of ​​the communication port 254, the larger the width of the thread groove 131a must also be increased is the same in the first embodiment shown in FIGS. 1 and 5(a) and 5(b), etc.

[0079] Under these circumstances, the turbomolecular pump 100 according to the first embodiment (see, for example, FIGS. 1 and 5(a) and 5(b)) is provided with a branched tubular part 242, which constitutes a radical discharge promoting structure, between the radical introduction port 218, which is connected to the plasma generator 210, and the communication port 254. Radicals are sent from the radical introduction port 218 to the communication port 254 via the branched tubular part 242. The area of ​​the inner wall (inner surface) of the branched tubular part 242 is smaller than the area of ​​the inner wall (inner surface) of the annular groove 232. Therefore, compared to the conventional technique in which radicals collide with the inner wall of the annular groove 232, the area of ​​the portion with which radicals may collide can be reduced, and deactivation of the radicals before they flow into the communication port 254 can be prevented. This makes it possible to effectively utilize the radicals.

[0080] Next, using Figure 8, we will present several examples of radical exhaust promotion structures and compare them with conventional structures. Figures 8(a1) and (a2) schematically show different types of radical exhaust promotion structures. Figures 8(b1) and (b2) schematically show examples of conventional flow paths. The example in Figure 8(a1) uses a tapered pipe shape, and the example in Figure 8(b1) uses a stepped pipe shape. The example in Figure 8(a2) uses a curved pipe shape, and the example in Figure 8(b2) uses a branched pipe shape.

[0081] Among these, in the stepped pipe shape of Fig. 8(b1) showing a conventional example, the cross-sectional area changes abruptly between a large-diameter portion 302 having an inlet and a small-diameter portion 304 having an outlet. A radical 306 traveling from the large-diameter portion 302 to the small-diameter portion 304 may collide with a wall surface at a step 308 between the large-diameter portion 302 and the small-diameter portion 304 and be reflected in the opposite direction. To enter the small-diameter portion 304, the radical 306 must undergo one or more collisions within the large-diameter portion 302. Therefore, by the time the radical 306 successfully enters the small-diameter portion 304, the radical 306 has lost a considerable amount of its activity.

[0082] Here, arrows B1 and B2 in Fig. (b1) indicate the direction in which radicals 306 should flow. Arrow C in Fig. (b1) indicates the direction in which radicals 306 flow. These points are the same in Figs. 8(a1), (a2), and (b2).

[0083] In contrast to the stepped pipe shape described above, the tapered pipe shape shown in Figure 8(a1), which illustrates an example of a radical exhaust promotion structure, has a cross-sectional area that gradually decreases from the inlet side to the outlet side. With this tapered pipe shape, even if radicals 306 are reflected on the inner wall, they are more likely to be reflected back in the flow direction, and the overall flow direction toward the outlet is maintained. Therefore, compared to the stepped pipe shape shown in Figure 8(b1), the number of collisions of radicals 306 with the inner wall can be reduced, preventing deactivation of radicals 306 and enabling effective utilization of radicals.

[0084] Next, in the branch pipe shape of the example of FIG. 8(b2), which shows a conventional example, a branched structure is formed. A branch pipe section 314 having an outlet is connected perpendicularly to a main pipe section 312 having an inlet at a midpoint. In this branch pipe shape, radicals are generated that do not flow from the main pipe section 312 into the branch pipe section 314 but pass through the branch pipe section 314. If a radical 316 happens to flow into the branch pipe section 314, this radical 316 heads toward the outlet. In this branch pipe shape, the radical 316 may pass through the branch pipe section 314. If the main pipe section 312 is formed in a ring shape, the radical will circulate.

[0085] In contrast, in the curved pipe shape of the example shown in Fig. 8(a2), which shows an example of a radical discharge promotion structure, the flow path is not branched, and radicals do not pass by without heading toward the outlet. This makes it possible to suppress the circulation of radicals and the number of collisions of radicals with the inner wall, and thus makes it possible to effectively utilize radicals.

[0086] In the first embodiment shown in FIG. 1 and FIGS. 5(a) and (b), the diameter of the opening at the inlet end 246 of the branched tubular part 242 is larger than the diameter of the opening at each of the outlet ends 248a, 248b. Therefore, the relationship between the inlet end 246 and the individual outlet ends 248a, 248b corresponds to the tapered pipe shape in FIG. 8(a1). Furthermore, in the first embodiment, the radical flow path does not branch from the annular groove 232 to the communication port 254, but is directly connected from the radical introduction port 218 to the communication port 254. Therefore, the relationship between the inlet end 246 and the individual outlet ends 248a, 248b also corresponds to the curved pipe shape in FIG. 8(a2).

[0087] Based on this idea, the inventors have decided to refer to structures such as the branched tubular part 242 shown in FIG. 1 and FIGS. 5(a) and (b), and structures having tapered or curved pipe shapes, etc., shown in FIGS. 8(a1) and (a2), as "radical discharge promotion structures." By providing such "radical discharge promotion structures" in the turbomolecular pump 100, radicals can be effectively utilized. The "radical discharge promotion structure" can also be referred to as, for example, a "radical deactivation prevention structure," a "radical effective utilization structure," or a "structure for suppressing a sudden decrease in the cross-sectional area of ​​the flow path." Furthermore, a radical flow path having a "radical discharge promotion structure" can also be referred to as a "radical flow path portion having a radical discharge promotion structure."

[0088] Increasing the number of communication ports 254 allows for more efficient introduction of radicals into the thread groove 131a. In this case, it is possible to increase the number of plasma generators 210 or the number of branches in the branch tubular part 242 in accordance with the increase in the number of communication ports 254. However, increasing the number of plasma generators 210 increases costs. In the first embodiment, the number of plasma generators 210 is three (three units, three devices, etc.), the number of branches in the branch tubular part 242 is two, and radicals are introduced into the thread groove 131a from six communication ports 254 (six locations). This makes it possible to effectively utilize radicals while suppressing costs.

[0089] Although not shown, radicals may be supplied from one plasma generator 210 to only one communication port 254. Furthermore, although not shown, when the thread groove 131a has multiple threads, it is also possible to provide one communication port 254 for each thread, and to provide one plasma generator for each communication port 254.

[0090] Furthermore, in the first embodiment, the inlet end 246 and the outlet end 248a, 248b of the branch tubular part 242 are formed to have at least a partially curved arc shape. However, this is not limited thereto, and for example, the inlet end 246 and the outlet end 248a, 248b may be formed as linearly as possible, and together with the main pipe portion 250, the entire end may be formed into a straight pipe shape. In this way, the number of times radicals collide with the inner wall can be further reduced overall.

[0091] <Surface treatment for radical emission promoting structure> The degree of deactivation due to radical collision is greater when the material of the collision surface (collision surface) is metal. Examples of metals include aluminum, iron, stainless steel, copper, and alloys containing these metals. For this reason, in the first embodiment, a non-metallized surface treatment is applied to the surface of the metal material with which radicals may collide. Examples of non-metallized surface treatments include anodizing and ceramic coating.

[0092] Examples of metal parts that may be hit by radicals include at least one of the branch tubular part 242, the threaded spacer 131, and the outer cylinder 127. Examples of target areas for the non-metallizing surface treatment of the branch tubular part 242 include the entire branch tubular part 242 provided with the radical discharge promoting structure, the inner wall surface, or a part of the branch tubular part 242 including the inner wall surface.

[0093] Furthermore, examples of the target area of ​​the non-metallizing surface treatment for the threaded spacer 131 include the entire threaded spacer 131, the inner wall surface, or a part of the threaded spacer 131 including the inner wall surface. Furthermore, examples of the target area of ​​the non-metallizing surface treatment for the outer cylinder 127 include the entire outer cylinder 127, the inner wall surface of the radical introduction port 128, or a part of the outer cylinder 127 including the inner wall surface of the radical introduction port 128.

[0094] In this way, by applying a non-metallic surface treatment to at least a part of the metal parts that radicals may collide with, the parts that radicals may collide with can be non-metallicized. This further prevents the radicals from being deactivated, and allows the radicals to be used more effectively. Note that the inlet pipe 216 may also be similarly subjected to a non-metallic surface treatment.

[0095] In the first embodiment, the annular groove 232 is formed in the threaded spacer 131, but this is not limiting and the annular groove 232 may be formed in another component (a component of the vacuum pump). Examples of the other component include the outer cylinder 127 and the base portion 129. The annular groove 232 may also be formed by combining grooves formed in a plurality of components. Examples of the plurality of components include a combination of the threaded spacer 131 and the outer cylinder 127, or a combination of the threaded spacer 131, the outer cylinder 127, and the base portion 129.

[0096] A tubular part (such as the branched tubular part 242) having a radical exhaust promoting structure can be provided in the annular groove 232 thus formed. The tubular part (such as the branched tubular part 242) may be disposed in any of the vacuum pump components, or the tubular part (such as the branched tubular part 242) may be provided so as to straddle a plurality of vacuum pump components. That is, a tubular part (such as the annular groove 232) can be disposed in a groove (such as the annular groove 232) provided in at least one of the casing (such as the outer cylinder 127, the base 129, or the combination of the outer cylinder 127 and the base 129 that constitute the casing) and the exhaust mechanism (such as the threaded spacer 131 that constitutes the Holweck-type exhaust mechanism 204).

[0097] Second Embodiment Next, a second embodiment of the vacuum pump of the present invention will be described. The same reference numerals are used for the same parts as those in the first embodiment, or the reference numerals are omitted and the description thereof will be omitted as appropriate. Fig. 9(a) shows a longitudinal section of a turbomolecular pump 400 according to the second embodiment, and Fig. 9(b) shows a cross section (planar cross section) of the connection between the inlet pipe 216 and the outer cylinder 127 in Fig. 9(a) as viewed from the top (the side of the intake port 101) in Fig. 9(a).

[0098] In the second embodiment, the radical discharge promoting structure is formed by an arc-shaped groove 432 of the threaded spacer 131. The arc-shaped groove 432 is an arc-shaped space that extends along the circumferential direction on the outer peripheral surface of the threaded spacer 131. There are three arc-shaped grooves 432, which are arranged at 120-degree intervals. FIG. 9(b) shows only one arc-shaped groove 432. The arc-shaped groove 432 faces the inner peripheral surface of the outer cylinder 127 and is defined by the threaded spacer 131 and the outer cylinder 127.

[0099] The arc-shaped groove 432 has an arc-shaped main flow path portion 450 and each end portion 428 a, 428 b. The main flow path portion 450 is spatially connected to the radical introduction port 218 of the outer cylinder 127 at a central portion 426 in the longitudinal direction (the circumferential direction of the threaded spacer 131).

[0100] A guide portion 482 is provided on the inner wall of the arc-shaped groove portion 432 at a portion facing the radical introduction port 218. The guide portion 482 is formed by processing a plate-like material into a shape having a sharp protrusion 452 in the center, and is fixed to the inner wall of the arc-shaped groove portion 432 with a plurality of screws 484. The tip of the protrusion 452 faces toward the center of the radical introduction port 218.

[0101] Metal can be used as the material of the guide portion 482. Examples of metal include aluminum, iron, stainless steel, copper, and alloys containing these metals as components.

[0102] Each end 428a, 428b of the arc-shaped groove 432 is at least partially formed in an arc shape and spatially connected to a communication port 454 provided in the threaded spacer 131. As shown in Fig. 9(b) , each end 428a, 428b of the arc-shaped groove 432 is formed in an arc shape and closes (is closed) at a position where the radical introduction port 218 is spatially connected to the communication port 454.

[0103] The communication openings 454 penetrate the bottom of the arc-shaped groove portion 432 in the threaded spacer 131, and spatially connect the thread groove 131a with the interior of the arc-shaped groove portion 432. Two communication openings 454 are formed for each arc-shaped groove portion 432. In this embodiment, a total of six (=2×3) communication openings 454 are provided around the entire circumference of the threaded spacer 131. The communication openings 454 are arranged symmetrically in pairs at 120-degree intervals around the circumference of the threaded spacer 131.

[0104] The diameter (inner diameter) of the opening (here, a circular opening) of the communication port 454 is smaller than the diameter (inner diameter) of the opening (here, a circular opening) of the radical introduction port 218. Furthermore, the arc-shaped groove 432 is formed so that the inner wall is smoothly continuous from the main flow path portion 450 to the end portions 428a, 428b and the communication port 454, with as few steps as possible. Furthermore, the main flow path portion 450 and the end portions 428a, 428b are formed so that the size of the flow path (cross-sectional area, flow path area) does not change as much as possible. In this way, the arc-shaped groove 432 connects the radical introduction port 218 disposed in the outer cylinder 127 to the communication port 454 disposed in the threaded spacer 131.

[0105] The radicals generated by the plasma generator 210 flow into the arc-shaped groove 432 through the valve device 214, which is controlled to an open state, and the inlet pipe 216. The radicals that flow into the arc-shaped groove 432 are diverted along the shape of the guide portion 482 and guided in the length direction of the arc-shaped groove 432. Furthermore, the radicals flow toward the communication port 454 at each end 428a, 428b of the arc-shaped groove 432, pass through the communication port 454, and are discharged into the thread groove 131a. The radicals discharged into the thread groove 131a mainly clean the thread groove pump mechanism (Hollweck-type exhaust mechanism 204), the boundary between the thread groove pump mechanism (Hollweck-type exhaust mechanism 204) and the turbomolecular pump mechanism 138, and other areas.

[0106] In the second embodiment, similarly to the first embodiment, non-metallizing surface treatment is performed on metal parts with which radicals may collide. Examples of non-metallizing surface treatment include anodizing and ceramic coating. Examples of metal parts with which radicals may collide include the threaded spacer 131 with the arc-shaped groove 432 formed therein, the guide portion 482 and the screw 484 fixed to the threaded spacer 131, and the outer cylinder 127 with the radical introduction port 128 formed therein.

[0107] The target areas of the non-metallized surface treatment for the guide portion 482 and the screw 484 may include the entire guide portion 482 and the screw 484, or portions where radicals may collide. The target areas of the non-metallized surface treatment for the threaded spacer 131 and the outer tube 127 are the same as those in the first embodiment.

[0108] In this way, by applying a demetallizing surface treatment to at least a part of a metal part that may be hit by radicals, the parts that may be hit by radicals can be demetallized, which further prevents the radicals from being deactivated and allows the radicals to be used more effectively.

[0109] According to the turbomolecular pump 400 of the second embodiment as described above, radicals can be introduced directly from the radical introduction port 218 to the communication port 454 without being largely dispersed or circulated. This makes it possible to achieve the same effects as those of the first embodiment. Furthermore, since the radical exhaust promotion structure is directly formed in the arc-shaped groove portion 432 of the threaded spacer 131, a component with a complex shape, such as the branched tubular component 242 of the first embodiment, is not required. The radical exhaust promotion structure of the arc-shaped groove portion 432 according to the second embodiment also corresponds to the tapered pipe shape of FIG. 8(a1) or the curved pipe shape of FIG. 8(a2).

[0110] In the second embodiment, the arc-shaped groove 432 is formed in the threaded spacer 131, but is not limited to this and may be formed in another component (a component of the vacuum pump). Examples of the other component include the outer cylinder 127 and the base 129. The arc-shaped groove 432 may also be formed by combining grooves formed in a plurality of components. Examples of the plurality of components include a combination of the threaded spacer 131 and the outer cylinder 127, or a combination of the threaded spacer 131, the outer cylinder 127, and the base 129.

[0111] The arc-shaped groove 432 thus formed can constitute a radical exhaust promotion structure. The groove (such as the arc-shaped groove 432) may be formed in any of the vacuum pump components, or the groove (such as the arc-shaped groove 432) may be formed so as to extend across a plurality of vacuum pump components. In other words, the radical exhaust promotion structure can be constituted by a groove (such as the arc-shaped groove 432) provided in at least one of the casing (such as the outer cylinder 127, the base 129, or the combination of the outer cylinder 127 and the base 129 that constitute the casing) and the exhaust mechanism (such as the threaded spacer 131 that constitutes the Holweck-type exhaust mechanism 204).

[0112] Furthermore, in the first and second embodiments, the number of plasma generators 210 is three (three units, three devices, etc.), the number of branches in the branch tubular part 242 and the arc-shaped groove portion 432 is two, and radicals are introduced into the thread groove 131a from six (six locations) communication ports 254, 454, the number of which is greater than the number of plasma generators 210. With regard to the relationship between the number of thread grooves 131a and the number of communication ports 254, 454, ideally one communication port 254 is provided for each thread groove 131a. In the first and second embodiments, by appropriately setting the number of branches in the branch tubular part 242, a structure is realized in which radicals can be introduced into each thread groove 131a.

[0113] <Third embodiment> Next, a third embodiment of the vacuum pump of the present invention will be described. The same reference numerals are used for the same parts as those in the first or second embodiment, or the reference numerals are omitted and the description thereof will be omitted as appropriate. Fig. 10 shows a longitudinal section of a turbomolecular pump 500 according to the second embodiment.

[0114] In the first and second embodiments, the Holweck-type exhaust mechanism 204 is provided as the thread groove pump mechanism of the exhaust mechanism 137. However, in the third embodiment, a Sigburn-type exhaust mechanism 504 is provided as the thread groove pump mechanism of the exhaust mechanism 137. The third embodiment combines a turbomolecular pump equipped with the Sigburn-type exhaust mechanism 504 with a radical exhaust promotion structure such as that of the first or second embodiment. FIG. 10 shows the Sigburn-type exhaust mechanism 504, and to avoid cluttering the illustration, the radical exhaust promotion structure such as that of the first or second embodiment is omitted.

[0115] In Sigburn type exhaust mechanism 504, a plurality of spiral groove channels 514 separated by ridges 512 are formed in the gap between rotating disks 506a and 506b provided on rotor 103 and fixed disks 510a and 510b provided on spacers 508a and 508b. In Sigburn type exhaust mechanism 504, rotating disks 506a and 506b impart tangential momentum to gas molecules diffused in spiral groove channels 514, and spiral groove channels 514 impart preferential directionality in the exhaust direction, thereby performing exhaust.

[0116] The ridges 512 and the spiral grooves 514 are provided on at least one of the rotating disks 506a and 506b and the fixed disks 510a and 510b. The Sigburn type exhaust mechanism 504 can have a general structure.

[0117] The radical exhaust promotion structure can also be applied to the plasma flow path connected to such a Sigburn-type exhaust mechanism 504. In the third embodiment, the introduction pipe 216 enters the radical introduction port 218 provided in the outer casing 127. An arc-shaped groove 532 is formed on the outer peripheral surface at the boundary between the spacers 508a and 508b. In the third embodiment, the arc-shaped groove 532 has a radical exhaust promotion structure similar to the arc-shaped groove 432 of the second embodiment (FIGS. 9(a) and 9(b)). In addition, the third embodiment also includes the guide 482 and the like according to the second embodiment, but the guide 482 and the like are not shown in FIG. 10.

[0118] The arc-shaped groove 532 is spatially connected to the radical introduction port 218, as in the second embodiment. Also, communication ports 554 are spatially connected to both ends of the arc-shaped groove 532, as in the second embodiment. The communication ports 554 open, for example, in a perfect circle, facing the space between the fixed disks 510a and 510b, and are spatially connected to spiral groove channels 514 formed on both plate surfaces of one of the fixed disks 510b (the fixed disk 510b located on the exhaust side of the turbomolecular pump 500, of the fixed disks 510a and 510b). In this way, the arc-shaped groove 532 connects the radical introduction port 218 disposed in the outer cylinder 127 to the communication port 554 formed between the spacers 508a and 508b.

[0119] The radicals generated by the plasma generator 210 flow into the arc-shaped groove 532 through the valve device 214, which is controlled to an open state, and the inlet pipe 216. The radicals that flow into the arc-shaped groove 532 flow along the arc-shaped groove 532 and are discharged into the spiral groove flow channel 514 through the communication port 554. The radicals discharged into the spiral groove flow channel 514 mainly clean parts such as the thread groove pump mechanism (Sigburn type exhaust mechanism 504) and the exhaust port 133.

[0120] The radical exhaust promotion structure according to the third embodiment may be formed by providing a piping component (e.g., the branched tubular component 242) as in the first embodiment and connecting the radical introduction port 218 and the communication port 554 with this piping component.

[0121] In the third embodiment, similarly to the first and second embodiments, a non-metallizing surface treatment is performed on metal components with which radicals may collide. Examples of non-metallizing surface treatments include anodizing and ceramic coating. An example of a metal component with which radicals may collide is the threaded spacer 131 with the arc-shaped groove 532 formed therein. The target portion of the non-metallizing surface treatment on the threaded spacer 131 is similar to that in the first and second embodiments. Furthermore, when a radical exhaust promoting structure similar to that in the first and second embodiments is employed, the non-metallizing surface treatment can be performed similarly to the first and second embodiments.

[0122] In this way, by applying a demetallizing surface treatment to at least a part of a metal part that may be hit by radicals, the parts that may be hit by radicals can be demetallized, which further prevents the radicals from being deactivated and allows the radicals to be used more effectively.

[0123] According to the turbomolecular pump 500 of the third embodiment as described above, radicals can be introduced directly from the radical introduction port 218 to the communication port 554 without being largely dispersed or circulated. Furthermore, the turbomolecular pump 500 of the type equipped with the Sigburn type exhaust mechanism part 504 can also achieve the same effects of the invention as those of the second embodiment (or the first embodiment).

[0124] <Inventions that can be extracted from each embodiment> The following inventions can be extracted from the above-described embodiments. (1) An exhaust mechanism (such as a turbomolecular pump mechanism unit 138 and a Holweck-type exhaust mechanism unit 204, or a turbomolecular pump mechanism unit 138 and a Sigburn-type exhaust mechanism unit 504) including a rotatable rotor (such as a rotor 103) and a stator (such as a fixed blade 123) combined with the rotor; A vacuum pump (turbomolecular pump 100, 400, 500, etc.) including a casing (a combination of an outer cylinder 127 and a base portion 129, the outer cylinder 127, the base portion 129, etc.) that contains the exhaust mechanism, A radical exhaust promotion structure is provided that connects a radical introduction port (radical introduction port 218, etc.) arranged in the casing with a communication port (communication port 254, 454, 554, etc.) arranged in the exhaust mechanism. A vacuum pump characterized by: (2) The radical discharge promoting structure is composed of a tubular part (such as the branched tubular part 242). The vacuum pump according to (1) above, characterized by: (3) The radical exhaust promotion structure is formed by a groove (such as the arc-shaped groove 432) provided in at least one of the casing (such as the outer cylinder 127, the base 129, or the combination of the outer cylinder 127 and the base 129 that constitute the casing) and the exhaust mechanism (such as the threaded spacer 131 that constitutes the Holweck-type exhaust mechanism 204). The vacuum pump according to (1) above, characterized by: (4) The groove is closed at a position where the radical introduction port is spatially connected to the communication port. The vacuum pump according to (3) above, characterized in that (5) The groove is provided with a guide portion (such as the guide portion 482) that guides the radicals that have passed through the radical introduction port toward the communication port. The vacuum pump according to (3) above, characterized in that (6) At least a part of at least one of the radical exhaust promotion structure, the communication port, and the radical introduction port is anodized. The vacuum pump according to any one of (1) to (5) above, characterized by: (7) At least a portion of at least one of the radical exhaust promoting structure, the communication port, and the radical introduction port is ceramic coated. The vacuum pump according to any one of the above (1) to (5), characterized in that: (8) an exhaust mechanism (such as a turbomolecular pump mechanism unit 138 and a Holweck-type exhaust mechanism unit 204, or a turbomolecular pump mechanism unit 138 and a Sigburn-type exhaust mechanism unit 504) including a rotatable rotor (such as the rotor 103) and a stator (such as the fixed blades 123) combined with the rotor; a vacuum pump component (such as a branched tubular part 242, a threaded spacer 131, the outer cylinder 127, the base part 129, or a combination of the threaded spacer 131 and the outer cylinder 127) used in a vacuum pump (such as a turbomolecular pump 100, 400, or 500) including a casing (such as a combination of the outer cylinder 127 and the base part 129, the outer cylinder 127, or the base part 129) that houses the exhaust mechanism, a radical introduction port (e.g., radical introduction port 218) disposed in the casing; A radical exhaust promoting structure is provided to connect the communication openings (communication openings 254, 454, 554, etc.) arranged in the exhaust mechanism. A vacuum pump component characterized by: (9) The tubular part (such as the branched tubular part 242) has the radical discharge promoting structure formed therein. The vacuum pump component according to (8) above, characterized by: (10) A component constituting at least one of the casing and the exhaust mechanism (such as the outer cylinder 127, the threaded spacer 131, the base portion 129, or the combination of the threaded spacer 131 and the outer cylinder 127). The vacuum pump component according to (8) above, characterized by:

[0125] <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. [Explanation of symbols]

[0126] 100, 400, 500: Turbomolecular pump 102: Rotor 103: Rotating body 127: Outer cylinder 129: Base 131: Threaded spacer 136: Rotation mechanism 137: Exhaust mechanism 138: Turbomolecular pump mechanism 204: Holweck type exhaust mechanism 210: Plasma generator 214: Valve equipment 216: Inlet piping 218: Radical introduction port 232, 532: Annular groove 242: Branched tubular parts 252:Protrusion 254, 454, 554: Connecting port 432: Arc-shaped groove 482: Information Department 504: Sigburn type exhaust mechanism

Claims

1. an exhaust mechanism including a rotatable rotor and a stator combined with the rotor; a casing that houses the exhaust mechanism, a radical exhaust promotion structure is provided that spatially connects a radical introduction port disposed in the casing and a communication port disposed in the exhaust mechanism, The radical discharge promoting structure guides the radicals from the radical introduction port to the corresponding communication port without dispersing the radicals beyond the communication port. A vacuum pump characterized by:

2. The radical exhaust promoting structure is constituted by a tubular part.

2. The vacuum pump according to claim 1,

3. The radical exhaust promotion structure is configured by a groove provided in at least one of the casing and the exhaust mechanism.

2. The vacuum pump according to claim 1,

4. An exhaust mechanism including a rotatable rotor and a stator combined with the rotor; a casing that houses the exhaust mechanism, a radical exhaust promotion structure is provided that spatially connects a radical introduction port disposed in the casing and a communication port disposed in the exhaust mechanism, the radical exhaust promotion structure is configured by a groove provided in at least one of the casing and the exhaust mechanism, The groove is closed at a position where the radical introduction port is spatially connected to the communication port. A vacuum pump characterized by:

5. The groove is provided with a guide portion that guides the radicals that have passed through the radical introduction port toward the communication port.

4. The vacuum pump according to claim 3,

6. At least a part of at least one of the radical exhaust promotion structure, the communication port, and the radical introduction port is anodized.

6. The vacuum pump according to claim 1, wherein

7. At least one of the radical exhaust promotion structure, the communication port, and the radical introduction port is at least partially coated with ceramic.

6. The vacuum pump according to claim 1, wherein

8. an exhaust mechanism including a rotatable rotor and a stator combined with the rotor; a casing that houses the exhaust mechanism, a radical exhaust promotion structure is provided that spatially connects a radical introduction port disposed in the casing and a communication port disposed in the exhaust mechanism, The radical discharge promoting structure guides the radicals from the radical introduction port to the corresponding communication port without dispersing the radicals beyond the communication port. A vacuum pump component characterized by:

9. The tubular part has the radical exhaust promotion structure formed thereon.

9. A vacuum pump component according to claim 8.

10. A component that constitutes at least one of the casing and the exhaust mechanism.

9. A vacuum pump component according to claim 8.

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