Cleaning device for vacuum exhaust system

Abstract

A cleaning device for a vacuum exhaust system capable of preventing deposits from reattaching downstream of a vacuum pump is provided. The cleaning device comprises: a cooling trap (13) capable of cooling a gas containing a sublimation component to generate deposits; at least one first vacuum pump (11) disposed upstream of the cooling trap (13); at least one first pipe (21) connecting the first vacuum pump (11) and the cooling trap (13); at least one second vacuum pump (16) disposed downstream of the cooling trap (13); and at least one second pipe (22) connecting the second vacuum pump (16) and the cooling trap (13). The cleaning device heats at least a portion of the first vacuum pump (11) and the first pipe (21) to a temperature above the sublimation temperature of the sublimation component, and cools the cooling trap (13) to a temperature below the sublimation temperature of the sublimation component.

Description

Technical Field

[0001] The present invention relates to a cleaning device for a vacuum exhaust system using, for example, a turbomolecular pump. Background Art

[0002] Generally speaking, a type of vacuum pump is known as a turbomolecular pump. In this type of pump, power is supplied to a motor within the pump body, causing rotor blades to rotate, ejecting gas molecules from the gas (process gas) drawn into the pump body. Furthermore, some turbomolecular pumps are equipped with heaters and cooling pipes to optimally manage the temperature within the pump.

[0003] [Patent Literature]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-80407.

[0005] Problems to be solved by the present invention

[0006] However, in vacuum pumps such as the turbomolecular pumps described above, substances in the transferred gas sometimes precipitate. For example, in the process of slowly increasing the pressure of the gas (process) sucked into the pump body by compressing the gas used in the etching process of semiconductor manufacturing equipment, the temperature of the exhaust flow path becomes lower than the sublimation temperature, which may cause side reaction products to precipitate inside the vacuum pump and piping, blocking the exhaust flow path. In addition, in the process of compressing the gas sucked from the pump's intake port inside the pump, the sucked gas sometimes exceeds the pressure at which the gas phase changes to a solid phase, and the phase changes to a solid inside the pump. As a result, solids as side reaction products sometimes accumulate inside the pump, causing defects due to the accumulation. Moreover, in order to remove the precipitated side reaction products, the vacuum pump and piping need to be cleaned. In addition, depending on the situation, the vacuum pump and piping need to be repaired or replaced with new ones. Moreover, in order to perform these maintenance operations, it is sometimes necessary to temporarily stop the semiconductor manufacturing equipment. Furthermore, the maintenance period sometimes lasts for more than several weeks depending on the situation.

[0007] Furthermore, some conventional vacuum pumps utilize a heater to raise the temperature of the internal exhaust path during normal exhaust operation to prevent the accumulation of side reaction products (Patent Document 1). In the invention disclosed in Patent Document 1, the pump's exhaust path is heated downstream to increase the sublimation pressure of the drawn gas, placing it in the vapor phase. This prevents the accumulation of side reaction products within the pump and potentially blocking the exhaust path. To prevent thermal expansion and deformation of the vacuum pump's components during heating, which could lead to contact between components, a temperature limit (the target heating temperature) is set to prevent the temperature from exceeding a set value.

[0008] Furthermore, the applicant has proposed a vacuum pump that features a function (also known as a "cleaning function," "cleaning mode," etc.) that heats the vacuum pump's gas flow path to gasify and remove deposits during standby mode, when the vacuum pump is not being used in processes such as semiconductor manufacturing (Japanese Patent Application No. 2019-165839). This vacuum pump can remove deposits during the vacuum pump's standby time, eliminating the need to maintain a high gas flow path temperature during the process. Consequently, the allowable flow rate in the vacuum pump can be increased.

[0009] Moreover, if further improvements are considered for this type of vacuum pump and the exhaust system incorporating the vacuum pump, it can be imagined that when the gas heated during cleaning flows through equipment such as the vacuum pump and piping arranged further downstream (lower level), the temperature of the gas decreases and the deposits will again adhere to the interior of the equipment on the downstream side. Summary of the Invention

[0010] An object of the present invention is to provide a cleaning device for a vacuum exhaust system that can prevent deposits from re-adhering downstream of a vacuum pump.

[0011] Means of solving problems

[0012] (1) In order to achieve the above-mentioned purpose, the present invention is a cleaning device for a vacuum exhaust system.

[0013] The vacuum exhaust system comprises:

[0014] A cooling trap that cools gases containing sublimated components to produce deposits.

[0015] at least one first vacuum pump disposed upstream of the cooling trap,

[0016] a first exhaust path connecting the first vacuum pump and at least one of the cooling traps;

[0017] at least one second vacuum pump disposed downstream of the cooling trap,

[0018] a second exhaust path connecting the second vacuum pump and at least one of the cooling traps;

[0019] Exhaust the aforementioned gas,

[0020] The cleaning device of the vacuum exhaust system is characterized in that:

[0021] At least the first vacuum pump or a portion of the first exhaust path is heated to a temperature equal to or higher than the sublimation temperature of the sublimating component, and the cooling trap is cooled to a temperature equal to or lower than the sublimation temperature of the sublimating component.

[0022] (2) In addition, in order to achieve the above-mentioned object, another present invention is a cleaning device for a vacuum exhaust system as described in (1), characterized in that:

[0023] The exhaust path includes a switching valve provided in at least one of the first exhaust paths, and a third exhaust path connecting the switching valve and at least one of the second exhaust paths.

[0024] (3) In addition, in order to achieve the above-mentioned object, another present invention is a cleaning device for a vacuum exhaust system as described in (1) or (2), characterized in that:

[0025] The cooling trap has:

[0026] A housing having an air intake port and an air exhaust port,

[0027] at least one plate-shaped portion disposed in the housing,

[0028] A cooling mechanism for cooling the plate-shaped portion.

[0029] (4) In addition, in order to achieve the above-mentioned object, another present invention is a cleaning device for a vacuum exhaust system as described in (3), characterized in that:

[0030] The cooling well is formed by stacking a plurality of the plate-like portions each having at least one opening with the openings being arranged in a phase-shifted manner.

[0031] (5) In addition, in order to achieve the above-mentioned object, another present invention is a cleaning device for a vacuum exhaust system as described in (3) or (4), characterized in that:

[0032] The cooling trap includes a rotating shaft provided in the housing and at least one scraper fixed to the rotating shaft, wherein the scraper is configured to be rotatable along a plate surface of the plate-shaped portion.

[0033] (6) In addition, in order to achieve the above-mentioned object, another present invention is a cleaning device for a vacuum exhaust system as described in any one of (1) to (5), characterized in that:

[0034] The exhaust gas recovery device includes a branch path provided in the second exhaust path, an on-off valve provided in the branch path, and a deposit recovery container provided downstream of the on-off valve.

[0035] (7) In addition, in order to achieve the above-mentioned object, another present invention is a cleaning device for a vacuum exhaust system as described in any one of (3) to (5), characterized in that:

[0036] The cooling trap includes a deposit discharge port provided in the housing of the cooling trap, an on-off valve disposed downstream of the deposit discharge port, and a deposit recovery container disposed downstream of the on-off valve.

[0037] Effects of the Invention

[0038] According to the above invention, it is possible to provide a cleaning device for a vacuum exhaust system that can prevent deposits from re-adhering downstream of a vacuum pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a block diagram schematically showing a cleaning device for a vacuum exhaust system according to a first embodiment of the present invention.

[0040] Figure 2 This is a longitudinal sectional view of a first vacuum pump (turbomolecular pump) according to a first embodiment of the present invention.

[0041] Figure 3 It is the circuit diagram of the amplifier circuit.

[0042] Figure 4 This is a flowchart showing the control when the current command value is larger than the detection value.

[0043] Figure 5 This is a flowchart showing the control when the current command value is smaller than the detection value.

[0044] Figure 6 It is a longitudinal sectional view showing the cooling well.

[0045] Figure 7 This is an enlarged longitudinal sectional view showing a portion of the cooling trap.

[0046] Figure 8 It is along Figure 6 Top view cross section along line A-A.

[0047] Figure 9 This is an explanatory diagram showing the function of the cooling trap.

[0048] Figure 10 This is a block diagram schematically showing a cleaning device for a vacuum exhaust system according to a second embodiment of the present invention.

[0049] Figure 11 This is a block diagram schematically showing a cleaning device for a vacuum exhaust system according to a third embodiment of the present invention.

[0050] Figure 12 This is a block diagram schematically showing a cleaning device for a vacuum exhaust system according to a fourth embodiment of the present invention.

[0051] Description of Reference Numerals

[0052] 10, 240, 250, 260 cleaning devices

[0053] 11, 11A, 11B first vacuum pump

[0054] 12, 12A, 12B switching valve

[0055] 13 Cooling Trap

[0056] 14 On / Off Valve

[0057] 15 Debris recovery container

[0058] 16, 16A, 16B second vacuum pump

[0059] 21, 21A, 21B first pipe (first exhaust path)

[0060] 22, 22A, 22B Second pipe (second exhaust path)

[0061] 23, 23A, 23B Third pipe (third exhaust path)

[0062] 24 branch pipes (branch paths)

[0063] 100 turbomolecular pump (first vacuum pump)

[0064] 201 shell

[0065] 202 air intake

[0066] 203 exhaust port (deposits discharge port)

[0067] 204 cooling mechanism (cooling mechanism)

[0068] 217 exhaust hole (deposits discharge outlet)

[0069] 221 Rotational axis

[0070] 222 scraping part

[0071] 223 circular plate-shaped parts (plate-shaped parts)

[0072] 234 transfer hole (opening). DETAILED DESCRIPTION

[0073] Hereinafter, a cleaning device for a vacuum exhaust system according to each embodiment of the present invention will be described with reference to the drawings. Figure 1 The structure of a cleaning apparatus 10 according to the first embodiment of the present invention is schematically shown in a block diagram. The cleaning apparatus 10 mainly includes a first vacuum pump 11, a switching valve 12, a cooling trap 13, an on-off valve 14, a deposit recovery container 15, and a second vacuum pump 16.

[0074] Furthermore, these devices 11-16 are connected via various piping. The first vacuum pump 11 and the cooling trap 13 are connected via a first piping 21, which serves as a first exhaust path. A switching valve 12 is disposed midway along the first piping 21. The cooling trap 13 and the second vacuum pump 16 are connected via a second piping 22, which serves as a second exhaust path. The various piping components are constructed by combining multiple piping parts. Since various common piping parts can be used, a detailed description of the piping parts will be omitted here.

[0075] The switching valve 12 is a component having a three-way valve structure, and the switching valve 12 is connected to the second pipe 22 via the third pipe 23 as the third exhaust path. In addition, the second pipe 22 is connected to the sediment recovery container 15 via a branch pipe 24 as a branch path, and the opening and closing valve 14 is arranged in the middle of the branch pipe 24. Here, Figure 1 Indicated at 25 is a fourth pipe connected to the suction side of the first vacuum pump 11 .

[0076] As the aforementioned first vacuum pump 11, Figure 2 The turbo molecular pump 100 is shown. In addition, as the cooling trap 13, a Figures 6-8 The specific structures of the turbomolecular pump 100 and the cooling trap 13 will be described later.

[0077] Furthermore, the deposit recovery container 15 is a member capable of accommodating deposits generated in the cooling trap 13. Various general types of vacuum pumps can be used as the second vacuum pump 16, but a dry pump is used here.

[0078] Next, the turbomolecular pump 100 used as the first vacuum pump 11 will be described. Figure 2 A turbomolecular pump 100 is shown. The turbomolecular pump 100 is, for example, Figure 1 The fourth pipe 25 shown above is connected to a vacuum chamber (not shown) of equipment to be exhausted, such as a semiconductor manufacturing apparatus.

[0079] Figure 2 A longitudinal sectional view of the turbomolecular pump 100 is shown. Figure 2 In the turbomolecular pump 100, an air intake port 101 is formed at the upper end of a cylindrical outer cylinder 127. Inside the outer cylinder 127, a rotating body 103 is provided. A plurality of rotor blades 102 (102a, 102b, 102c, etc.) are radially arranged in multiple stages around the circumference of the rotating body 103. The rotor shaft 113 is mounted at the center of the rotating body 103. This rotor shaft 113 is suspended in mid-air and positionally controlled using, for example, a five-axis magnetic bearing.

[0080] The upper radial electromagnets 104 are four electromagnets arranged in pairs along the X-axis and the Y-axis. Four upper radial sensors 107 are provided near and corresponding to each of the upper radial electromagnets 104. The upper radial sensors 107 employ, for example, inductive sensors or eddy current sensors having conductive windings. These sensors detect the position of the rotor shaft 113 based on changes in the inductance of the conductive windings that vary with the position of the rotor shaft 113. These upper radial sensors 107 are configured to detect radial displacement of the rotor shaft 113, that is, the rotating body 103 fixed thereto, and transmit this information to a control device (not shown).

[0081] In this control device, a compensation circuit having, for example, a PID control 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. An amplifier circuit 150 (described later) 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.

[0082] Furthermore, the rotor shaft 113 is formed from a high-permeability material (such as iron or stainless steel) and is attracted by the magnetic force of the upper radial electromagnet 104. This adjustment is performed independently in the X-axis and Y-axis directions. Furthermore, the lower radial electromagnet 105 and lower radial sensor 108 are arranged similarly to the upper radial electromagnet 104 and upper radial sensor 107, allowing the lower radial position of the rotor shaft 113 to be adjusted in the same manner as the upper radial position.

[0083] Furthermore, axial electromagnets 106A and 106B are arranged above and below, sandwiching a disc-shaped metal disk 111 provided on the lower portion of rotor shaft 113. Metal disk 111 is made of a high-permeability material such as iron. An axial sensor 109 is provided to detect axial displacement of rotor shaft 113, and its axial position signal is transmitted to the control device.

[0084] Moreover, in the control device, for example, a compensation circuit having a PID adjustment function generates respective 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. The amplification circuit 150 performs excitation control on the axial electromagnet 106A and the axial electromagnet 106B based on these excitation control command signals. The axial electromagnet 106A attracts the metal disk 111 upward by magnetic force, and the axial electromagnet 106B attracts the metal disk 111 downward, thereby adjusting the axial position of the rotor shaft 113.

[0085] In this way, the control device appropriately adjusts the magnetic forces exerted by the axial electromagnets 106A and 106B on the metal disk 111, magnetically levitating the rotor shaft 113 in the axial direction and spatially holding it in a contactless manner. 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 in detail later.

[0086] Meanwhile, motor 121 includes a plurality of magnetic poles arranged circumferentially around rotor shaft 113. Each magnetic pole is controlled by a control device so as to rotate rotor shaft 113 via electromagnetic forces acting between the magnetic poles and rotor shaft 113. Furthermore, motor 121 incorporates a rotational speed sensor (not shown), such as a Hall effect element, resolver, or encoder, to detect the rotational speed of rotor shaft 113 using a detection signal from the rotational speed sensor.

[0087] Furthermore, for example, a phase sensor (not shown) is mounted near the lower radial sensor 108 to detect the rotation phase of the rotor shaft 113. The control device detects the position of the magnetic pole using detection signals from the phase sensor and the rotation speed sensor.

[0088] Multiple fixed blades 123a, 123b, 123c, etc. are arranged with minute gaps between them and the rotor blades 102 (102a, 102b, 102c, etc.). The rotor blades 102 (102a, 102b, 102c, etc.) are each tilted at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113, in order to move exhaust gas molecules downward by impact.

[0089] The stator blades 123 are similarly formed at a predetermined angle tilted from a plane perpendicular to the axis of the rotor shaft 113, and are arranged inwardly of the outer cylinder 127, staggered relative to the rotor blades 102. The outer ends of the stator blades 123 are supported by being interposed between a plurality of stacked stator blade spacers 125 (125a, 125b, 125c, etc.).

[0090] The stator spacer 125 is an annular member made of a metal such as aluminum, iron, stainless steel, copper, or an alloy containing these metals. The outer cylinder 127 is fixed to the outer periphery of the stator spacer 125 with a slight gap therebetween. A base 129 is provided at the bottom of the outer cylinder 127. An exhaust port 133 is formed in the base 129 and communicates with the outside. Exhaust gas that has moved to the base 129 is sent to the exhaust port 133.

[0091] Furthermore, depending on the application of the turbomolecular pump 100, a threaded washer 131 is disposed between the lower portion of the fixed blade washer 125 and the base 129. The threaded washer 131 is a cylindrical member made of a metal such as aluminum, copper, stainless steel, iron, or an alloy containing these metals. Multiple spiral thread grooves 131a are engraved on its inner circumference. The spiral direction of the thread grooves 131a aligns with the direction in which exhaust gas molecules are transported toward the exhaust port 133 as they move in the direction of rotation of the rotor 103. A cylindrical portion 102d extends downward from the lowest portion of the rotor 103, connected to the rotor blades 102 (102a, 102b, 102c, etc.). The outer circumference of this cylindrical portion 102d is cylindrical and projects toward the inner circumference of the threaded washer 131, remaining adjacent to the inner circumference of the threaded washer 131 with a predetermined gap therebetween. The exhaust gas transferred to the thread groove 131 a by the rotary blade 102 and the fixed blade 123 is sent to the base portion 129 while being guided to the thread groove 131 a .

[0092] The base 129 is a disc-shaped component that forms the base of the turbomolecular pump 100 and is generally made of a metal such as iron, aluminum, or stainless steel. The base 129 physically holds the turbomolecular pump 100 and also serves as a heat transfer path. Therefore, it is desirable to use a metal such as iron, aluminum, or copper that is rigid and has a high heat transfer rate.

[0093] In the above configuration, when rotor blades 102 and rotor shaft 113 are rotated by motor 121, exhaust gas is drawn from the chamber through intake port 101 by the action of rotor blades 102 and fixed blades 123. Exhaust gas drawn in through intake port 101 passes between rotor blades 102 and fixed blades 123 and is delivered to base 129. At this point, the temperature of rotor blades 102 rises due to frictional heat generated when exhaust gas contacts rotor blades 102 and heat conduction from motor 121. This heat is then transferred to fixed blades 123 through radiation or conduction via exhaust gas molecules.

[0094] The stator blade spacers 125 are joined to each other at their outer circumferences, and transfer heat received by the stator blades 123 from the rotor blades 102 , frictional heat generated when exhaust gas contacts the stator blades 123 , and the like to the outside.

[0095] In the above description, the threaded washer 131 is disposed on the outer periphery of the cylindrical portion 102d of the rotating body 103, and the thread groove 131a is engraved on the inner peripheral surface of the threaded washer 131. However, in some cases, the thread groove is engraved on the outer peripheral surface of the cylindrical portion 102d, and a washer having a cylindrical inner peripheral surface is disposed around the threaded washer 131.

[0096] In addition, depending on the purpose of the turbomolecular pump 100, the electrical equipment is sometimes covered by a stator column 122. The stator column 122 is maintained at a predetermined pressure by a purge gas so that the gas sucked from the intake port 101 does not invade the electrical equipment 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, 106B, the axial sensor 109, etc.

[0097] In this case, a pipe (not shown) is provided on the base portion 129, through which purge gas is introduced. The introduced purge gas passes through the gaps between the protective bearing 120 and the rotor shaft 113, between the rotor and stator of the motor 121, and between the stator column 122 and the inner cylindrical portion of the rotor blade 102, and is then delivered to the exhaust port 133.

[0098] The turbomolecular pump 100 requires control based on model-specific, individually adjusted parameters (e.g., characteristics specific to the model). To accommodate these control parameters, the turbomolecular pump 100 includes an electronic circuit unit 141 within its main body. This electronic circuit unit 141 includes semiconductor memory such as an EEPROM, electronic components such as semiconductor elements for accessing these memories, and a substrate 143 for mounting these components. This electronic circuit unit 141 is housed below a rotational speed sensor (not shown) near the center of the base 129 that forms the lower portion of the turbomolecular pump 100, for example, and is sealed by an airtight bottom cover 145.

[0099] However, in semiconductor manufacturing processes, some process gases introduced into the chamber have the property of solidifying if their pressure exceeds a predetermined value or their temperature falls below a predetermined value. Within the turbomolecular pump 100, the exhaust gas pressure is lowest at the intake port 101 and highest at the exhaust port 133. If the process gas pressure exceeds a predetermined value or its temperature falls below a predetermined value during its transfer from the intake port 101 to the exhaust port 133, the process gas solidifies and accumulates inside the turbomolecular pump 100.

[0100] For example, when SiCl4 is used as a process gas in an Al etching device, the vapor pressure curve shows that in a low vacuum (760 [torr] ~ 10 -2 At high temperatures (torr) and low temperatures (approximately 20°C), solid products (such as AlCl3) precipitate and deposit inside the turbomolecular pump 100. Consequently, if process gas precipitates accumulate inside the turbomolecular pump 100, the deposits narrow the pump flow path, causing performance degradation of the turbomolecular pump 100. Consequently, the aforementioned products are prone to solidifying and depositing in high-pressure areas near the exhaust port and the threaded gasket 131.

[0101] Therefore, in order to solve this problem, in the past, a heater not shown and a ring-shaped water-cooling pipe 149 were wound around the outer periphery of the base part 129, etc., and a temperature sensor not shown (such as a thermistor) was embedded in the base part 129, for example, so that the temperature of the base part 129 was maintained at a certain high temperature (set temperature) based on the signal of the temperature sensor, and the heating of the heater and the cooling of the water-cooling pipe 149 were controlled (hereinafter referred to as TMS. TMS; Temperature Management System).

[0102] Next, regarding the turbomolecular pump 100 configured as described above, the amplifier circuit 150 for controlling the excitation of the upper radial electromagnet 104 , the lower radial electromagnet 105 , and the axial electromagnets 106A and 106B will be described. Figure 3 A circuit diagram showing the amplifier circuit.

[0103] exist Figure 3 In the embodiment, one end of the electromagnet winding 151 constituting the upper radial electromagnet 104 and the like is connected to the positive electrode 171a of the power supply 171 via the transistor 161, and the other end is connected to the negative electrode 171b of the power supply 171 via the current detection circuit 181 and the transistor 162. Furthermore, the transistors 161 and 162 are so-called power MOSFETs, and have a structure in which a diode is connected between their drains.

[0104] At this time, transistor 161 has its diode cathode terminal 161a connected to anode 171a and its anode terminal 161b connected to one end of electromagnet winding 151. Transistor 162 has its diode cathode terminal 162a connected to current detection circuit 181 and its anode terminal 162b connected to cathode 171b.

[0105] Meanwhile, the cathode terminal 165a of the current regeneration diode 165 is connected to one end of the electromagnet winding 151, and the anode terminal 165b is connected to the negative electrode 171b. Similarly, the cathode terminal 166a of the current regeneration diode 166 is connected to the positive electrode 171a, and the anode terminal 166b is connected to the other end of the electromagnet winding 151 via the current detection circuit 181. The current detection circuit 181 is composed of, for example, a Hall effect sensor and a resistor element.

[0106] The amplifier circuit 150 configured as described above corresponds to one electromagnet. Therefore, if the magnetic bearing is controlled in a five-axis manner and there are ten electromagnets (104, 105, 106A, 106B), each electromagnet has a corresponding amplifier circuit 150, and the ten amplifier circuits 150 are connected in parallel to the power supply 171.

[0107] Furthermore, the amplification control circuit 191 is constituted by, for example, a digital signal processor unit (hereinafter referred to as a DSP unit) of a control device (not shown), and switches the transistors 161 and 162 on and off.

[0108] Amplification control circuit 191 compares the current value detected by current detection circuit 181 (a signal reflecting this current value is referred to as current detection signal 191c) with a predetermined current command value. Based on this comparison result, it determines the pulse width (pulse width times Tp1 and Tp2) generated within one cycle of PWM control, or control cycle Ts. As a result, amplification control circuit 191 outputs gate drive signals 191a and 191b having these pulse widths to the gate terminals of transistors 161 and 162.

[0109] Furthermore, when the rotating body 103 passes through a resonance point during accelerated operation or when external disturbances occur during constant speed operation, high-speed and powerful position control of the rotating body 103 is required. Therefore, a high voltage of, for example, approximately 50V is used as the power supply 171 to enable a rapid increase (or decrease) in the current flowing through the electromagnet winding 151. Furthermore, a capacitor (not shown) is typically connected between the positive electrode 171a and the negative electrode 171b of the power supply 171 to stabilize the power supply 171.

[0110] In the above configuration, when both the transistors 161 and 162 are turned on, the current flowing through the electromagnet winding 151 (hereinafter referred to as the electromagnet current iL) increases, and when both are turned off, the electromagnet current iL decreases.

[0111] Furthermore, if one of transistors 161 and 162 is turned on and the other is turned off, a so-called flywheel current is maintained. Furthermore, by allowing the flywheel current to flow through amplifier circuit 150 in this manner, hysteresis loss in amplifier circuit 150 can be reduced, thereby suppressing power consumption in the entire circuit. Furthermore, by controlling transistors 161 and 162 in this manner, high-frequency noise such as high-pitched waves generated in turbomolecular pump 100 can be reduced. Furthermore, by measuring this flywheel current with current detection circuit 181, the electromagnet current iL flowing through electromagnet winding 151 can be detected.

[0112] That is, when the detected current value is less than the current command value, Figure 4 As shown, in a control cycle Ts (e.g., 100 μs), both transistors 161 and 162 are turned on once for a time corresponding to pulse width Tp1. Therefore, during this period, electromagnet current iL increases from positive electrode 171a to negative electrode 171b toward current value iLmax (not shown), which is a value that allows it to flow through transistors 161 and 162.

[0113] On the other hand, when the detected current value is greater than the current command value, Figure 5 As shown, in control cycle Ts, both transistors 161 and 162 are turned off once for a period of time corresponding to pulse width Tp2. Therefore, during this period, electromagnet current iL decreases from negative electrode 171b to positive electrode 171a toward current value iLmin (not shown), which can be regenerated via diodes 165 and 166.

[0114] In either case, one of the transistors 161 and 162 is turned on after the pulse width time Tp1 or Tp2 has elapsed. Therefore, during this period, the flywheel current is maintained in the amplifier circuit 150.

[0115] The turbomolecular pump 100 having such a basic structure is: Figure 2 The upper side (the side of the air inlet 101) is the air inlet connected to the target device, and the lower side (the side of the air outlet 133 protruding to the left in the figure and provided on the side of the base 129) is the air outlet connected to the cooling trap 13, the second vacuum pump 16 (rough suction auxiliary pump (backup pump)), etc. Figure 2 In addition to the vertical posture shown in the vertical direction, an inverted posture, a horizontal posture, and an inclined posture can also be used.

[0116] In the turbomolecular pump 100, the outer cylinder 127 and base portion 129 are combined to form a housing (hereinafter sometimes referred to as the "main body housing"). Furthermore, the turbomolecular pump 100 is electrically (and structurally) connected to a box-shaped electrical housing (not shown), in which the control device is incorporated.

[0117] The internal structure of the turbomolecular pump 100's main body casing (a combination of the outer cylinder 127 and the base 129) can be divided into a rotating mechanism, which rotates the rotor shaft 113 and other components via the motor 121, and an exhaust mechanism, which is rotationally driven by the rotating mechanism. Furthermore, the exhaust mechanism can be considered to be divided into the turbomolecular pump mechanism consisting of the rotating blades 102 and the fixed blades 123, and the threaded groove pump mechanism consisting of the cylindrical portion 102d and the threaded gasket 131.

[0118] The purge gas (shielding gas) is used to protect the bearings and rotor blades 102, prevent corrosion caused by exhaust gas (process gas), and cool the rotor blades 102. The purge gas can be supplied by common means.

[0119] For example, although not shown, a purge gas flow path extending linearly in the radial direction is provided at a predetermined location (e.g., approximately 180 degrees from the exhaust port 133) of the base portion 129. Purge gas is supplied to this purge gas flow path (more specifically, a purge port serving as a gas inlet) from outside the base portion 129 via a purge gas tank (e.g., an N2 gas tank), a flow regulator (a valve device), and the like.

[0120] The aforementioned protection bearing 120 is also known as a "ground-to-ground (T / D) bearing" or "backup bearing." Using these protection bearings 120, even in the event of a malfunction such as an electrical system failure or atmospheric intrusion, the position and orientation of the rotor shaft 113 will not change significantly, preventing damage to the rotor blades 102 and their surroundings.

[0121] In addition, in each figure ( Figure 2 In order to avoid complicating the drawings, the hatching lines representing the cross sections of the parts are omitted.

[0122] Next, the gas path and gas state changes in the cleaning apparatus 10 will be described. The cleaning apparatus 10 will be described below mainly using the term "first vacuum pump" for the turbomolecular pump 100 serving as the first vacuum pump 11 .

[0123] To the exhaust port 133 ( Figure 2 ) The gas sent out (hereinafter referred to as "exhaust gas") flows into Figure 1 The exhaust gas flowing into the first pipe 21 is guided to the cooling trap 13 side or the third pipe 23 side according to the state of the switching valve 12.

[0124] When the exhaust gas is directed toward the cooling trap 13, it is heated for cleaning. Specifically, this embodiment utilizes a function (also referred to as a "cleaning function," "cleaning mode," etc.) that heats the gas flow path of the first vacuum pump 11, gasifying and removing deposits. This cleaning function can employ a heating method similar to that proposed in Japanese Patent Application No. 2019-165839 filed by the present applicant.

[0125] If the above cleaning function is more specifically embedded in this embodiment, it is necessary to heat the exhaust gas to a temperature higher than the cleaning temperature (sublimation temperature) during cleaning. For this purpose, a heater can be provided. As a configuration of the heater, in the first vacuum pump 11 (turbo molecular pump 100) of this embodiment, the following can be mentioned: Figure 2The inner portion and outer periphery of the threaded gasket 131 shown in FIG. The threaded gasket 131 is a part of the aforementioned thread groove pump mechanism and can be a component constituting the traction pump portion.

[0126] In addition, as a part where a heater is provided, in addition to the threaded liner 131, examples include the interior or outer periphery of the base portion 129. Furthermore, heaters may be provided on both the base portion 129 and the threaded liner 131. Furthermore, the heater may be dedicated to the cleaning function, or the aforementioned TMS heater may be used for the cleaning function as well.

[0127] Furthermore, as the heater, various general heaters such as a cartridge heater, a sheath heater, and an induction heater (IH heater) can be adopted depending on their characteristics.

[0128] The portion heated by the heater is not limited to the first vacuum pump 11, and may be, for example, any portion in the first pipe 21 connecting the first vacuum pump 11 and the cooling well 13. Examples of such portions in the first pipe 21 include a portion immediately after the first vacuum pump 11, a portion between the first vacuum pump 11 and the switching valve 12, and a portion between the switching valve 12 and the cooling well 13. Furthermore, the heater may be installed either inside or outside the first pipe 21, or both.

[0129] This heating by the heater is performed to prevent deposits from forming in the gas flow path between the first vacuum pump 11 and the first pipe 21, and to vaporize any deposits that do form. Furthermore, during cleaning, the heated gas flows from the first vacuum pump 11 through the first pipe 21 to the cooling trap 13, where it is cooled.

[0130] In cooling trap 13, solids are actively precipitated by cooling the gas, resulting in deposits caused by components contained in the gas (sublimated components). The overall structure and function of cleaning apparatus 10 are described here. The specific structure of cooling trap 13 and the role of cooling trap 13 in generating deposits will be explained in detail later.

[0131] The deposits generated by the cooling trap 13 are discharged from the cooling trap 13 into the second pipe 22, pass through the junction 26 where the second pipe 22 and the branch pipe 24 merge, and fall toward the branch pipe 24. At this time, an on-off valve 14 provided midway along the branch pipe 24 opens the gap between the cooling trap 13 and the deposit recovery container 15. The deposits discharged from the cooling trap 13 then pass through the branch pipe 24 and fall toward the deposit recovery container 15, where they are recovered.

[0132] The second pipe 22 connects the cooling trap 13 to the second vacuum pump 16. Furthermore, the second vacuum pump 16 is in operation, assisting in the exhaust of gas from the first vacuum pump 11. Furthermore, most of the gas that has caused the deposit in the cooling trap 13 flows toward the second pipe 22 due to the operation of the second vacuum pump 16 and is exhausted by the second vacuum pump 16.

[0133] On the other hand, when cleaning is not in progress (e.g., during a semiconductor manufacturing process), the gas path is switched by a switching valve 12 located at the junction of the first and third pipes 21 and 23. As described above, the second vacuum pump 16 is in operation, assisting in the exhaust of gas from the first vacuum pump 11. The exhaust gas from the first vacuum pump 11 is then directed to the third pipe 23, and then flows into the second pipe 22 from the junction 27 where the third and second pipes 23 and 22 meet, where it is exhausted by the second vacuum pump 16.

[0134] Next, the specific structure of the cooling trap 13 and the effect of the cooling trap 13 on the deposition will be described in detail. Figure 6 As shown in the longitudinal section, it includes a housing 201, an air intake port 202, an air exhaust port 203, a cooling mechanism 204, and a motor 205. Figures 6-8 In order to avoid complicating the drawings, the hatching lines representing the cross sections of the parts are omitted.

[0135] The housing 201 is composed of a cylindrical housing body 211 and a disc-shaped cover 212. A top plate 213 is integrally formed with the housing body 211, and closes one axial end (the upper portion in the figure) of the housing body 211.

[0136] The cover 212 is a separate component from the housing body 211 and is connected to the housing body 211 by fixing means (hexagonal bolts, etc.) not shown. The cover 212 also hermetically seals the other axial end (the lower portion in the figure) of the housing body 211.

[0137] An air intake hole 214 is formed in the top plate 213 of the housing body 211, extending through the top plate 213 along its thickness. A circular tubular air intake pipe 215 extends from the outside of the top plate 213, connecting to the portion where the air intake hole 214 is located. This air intake pipe 215 forms the aforementioned air intake port 202. Furthermore, the air intake port 202 is formed radially away from the axis B of the housing 201 (indicated by the dashed line in the figure) and extends approximately parallel to the axis B of the housing 201.

[0138] The cover 212 has an exhaust hole 217 formed therein, extending through the cover 212 in the thickness direction. A circular exhaust pipe 218 is connected from the outside of the cover 212 to the portion where the exhaust hole 217 is provided. This exhaust pipe 218 forms the aforementioned exhaust port 203. Furthermore, the exhaust hole 217 and the exhaust port 203 form a deposit discharge port (reference numeral omitted). Here, the exhaust hole 217 alone can be considered the deposit discharge port.

[0139] The exhaust port 203 is formed at a position radially spaced from the axis B of the housing 201 and extends substantially parallel to the axis B of the housing 201. Furthermore, the exhaust port 203 extends in a direction opposite to the intake port 202 with respect to the axial direction of the housing 201 and is arranged 180 degrees out of phase with the intake port 202 with respect to the circumferential direction of the housing 201.

[0140] The cooling mechanism 204 includes a rotating shaft (rotor shaft of the cooling trap 13 ) 221 , a scraper 222 , a disk-shaped component 223 , bearings 224 and 225 , and is housed in the housing 201 .

[0141] The motor 205 is fixed to the cover 212 of the housing 201 from the outside, and its output shaft (not shown) is inserted into the rotating shaft 221 of the cooling mechanism 204. Furthermore, the output shaft (not shown) of the motor 205 is coaxially connected to the rotating shaft 221. Various common motors can be used as the motor 205.

[0142] The rotating shaft 221 of the cooling mechanism 204 is a stepped cylindrical component, with its axis (reference numeral omitted) roughly aligned with the axis B of the housing 201. Furthermore, one axial end (the upper end in the figure) of the rotating shaft 221 is rotatably supported by the housing body 211 via a bearing 224 on the intake side, while the other axial end (the lower end in the figure) of the rotating shaft 221 is rotatably supported by the cover 212 via a bearing 225 on the exhaust side.

[0143] The scraping part (also called "scraper") 222 is a rod-shaped body with a rectangular cross section, and is formed on the rotating shaft 221 by integral processing (or can be assembled separately). Furthermore, the scraping part 222 is formed in multiple stages (here, 7 stages) by forming a set of two scraping parts protruding in opposite directions in the radial direction of the rotating shaft 221. Figure 6 In the illustrated example, seven sets (a total of 14) of scraping portions 222 are formed at substantially equal intervals from one another along the axial direction of the rotating shaft 221 .

[0144] That is, the scraping portion 222 of each group is as follows Figure 6 as well as Figure 7As shown, the scraping parts 222 of each group are formed so as to be located on the same straight line with a phase difference of 180 degrees. Furthermore, the scraping parts 222 of each group extend substantially line-symmetrically with the axis of the rotating shaft 221 (here, coinciding with the axis B of the housing 201) as the center.

[0145] Furthermore, the seven groups of scrapers 222 are arranged in the same phase (in phase) with respect to the circumference of the rotating shaft 221, and are arranged substantially evenly along the axial direction of the rotating shaft 221. Furthermore, when the motor 205 is driven and the rotating shaft 221 is rotated in a predetermined direction by the motor 205, the scrapers 222 rotate and displace integrally with the rotating shaft 221 about the rotating shaft 221.

[0146] Here, the rotation direction of the motor 205 and the rotation shaft 221 can be Figure 8 In addition, the motor 205 can be controlled to rotate in the direction opposite to the normal rotation direction according to the situation.

[0147] Furthermore, when the scraper 222 is formed separately from the rotating shaft 221 and assembled to the rotating shaft 221, it is conceivable to form the scraper 222 on the outer circumferential surface of a cylindrical part (not shown), and to insert and fix the rotating shaft 221 into the cylindrical part. Alternatively, it is conceivable to form only a portion of the scraper 222 on the cylindrical part (for example, one to three sets), and to fix multiple cylindrical parts to the rotating shaft 221.

[0148] The aforementioned disk-shaped parts 223 are stacked in multiple stages (here, 6 stages) in the housing 201. Figure 6 、 Figure 8 As shown, the disc is processed into a perfect circle, and the outer periphery is made of a thick-walled liner 231, which is overlapped along the axial direction of the housing 201. The liner 231 is used to ensure a predetermined size of gap between each disc-shaped part 223 to form a plurality of deposit transfer spaces 232 ( Figure 7 ).

[0149] Furthermore, the top plate portion 213 of the housing body 211 and the disk-shaped part 223 ( Figure 6 as well as Figure 7 A deposit transfer space 232 is formed between the cover 212 and the disc-shaped part 223 ( Figure 6 The six disc-shaped parts 223 are fixed in the housing 201 in a state of being sandwiched between the top plate portion 213 and the cover portion 212 of the housing body 211.

[0150] The portion of each disk-shaped component 223 that is located inside (also referred to as “radially inside”, “inner peripheral side”, etc.) the spacer 231 is a true circular cooling portion 233 . The cooling portion 233 has a substantially constant thickness that is thinner than the spacer 231 .

[0151] In the cooling section 233, the transfer hole 234, which is an opening for transferring the deposited material, is formed in a perfect circular shape. One transfer hole 234 is provided on each of the circular plate-shaped parts 223. The transfer hole 234 is arranged at the outer peripheral edge (outermost peripheral portion) of the cooling section 233, and is located slightly in front of the pad 231 (inner peripheral portion). The positional relationship between the scraper 222 and the transfer hole 234 is as follows: Figure 8 As shown, when the scraper 222 is located at a position passing through the center of the transfer hole 234 , the tip of the scraper 222 reaches the outermost periphery of the transfer hole 234 and substantially overlaps with the outermost periphery of the transfer hole 234 .

[0152] Furthermore, the transfer holes 234 provided in the six disk-shaped components 223 are arranged so that their phases are alternately shifted by 180 degrees with respect to the circumferential direction of the cooling unit 233. Specifically, the transfer holes 234 of the first disk-shaped component 223 (the portion closest to the air intake hole 214), the third disk-shaped component 223, and the fifth disk-shaped component 223, from the air intake hole 214, are arranged in phase. Figure 6 In the embodiment, these transfer holes 234 are positioned on the right side of the rotation shaft 221 so as to be arranged in the same straight line.

[0153] On the other hand, in the second, fourth, and sixth disc-shaped parts 223 from the air intake hole 214, the transfer holes 234 are on the opposite side of the rotation shaft 221 ( Figure 6 The left side of the rotation axis 221 in the figure) is positioned so as to be arranged in the same straight line.

[0154] Here, Figure 8 Shown in Figure 6 The state of being cut along the radial direction along the line AA between the first and second disc-shaped parts 223 of the air intake hole 214. Figure 8 The transfer hole 234 shown by the solid line (the transfer hole 234 shown on the left side of the figure) is a hole formed in the circular plate-shaped part 223 second from the suction hole 214, and the transfer hole 234 shown by the dotted line (hidden line) (the transfer hole 234 shown on the right side of the figure) is a hole formed in the circular plate-shaped part 223 third.

[0155] The distance between the plate surface of the cooling part 233 and the scraping part 222 is determined in such a way that when the rotating shaft 221 rotates and the scraping part 222 is displaced relative to the plate surface of the cooling part 233, the scraping part 222 will not generate excessive pressure while contacting the plate surface of the cooling part 233 and hinder the displacement of the scraping part 222.

[0156] Here, in Figure 6 、 Figure 7 In the figure, the size of the gap between the plate surface of the cooling section 233 and the scraper 222 is emphasized to easily identify the presence of the two components (scraper 222 and cooling section 233). Furthermore, the scraper 222 is in contact with the plate surface of the cooling section 233 with a pressure sufficient to allow smooth displacement of the scraper 222. Furthermore, the scraper 222 can be made of a thin metal sheet or a synthetic resin with sufficient hardness and flexibility.

[0157] also, Figure 6 Indicated by reference numeral 236 is a cooling pipe built into the cover 212. This cooling pipe 236 is a circular tube with a true circular cross-section and is circumferentially arranged within the cover 212. Cooling liquid (e.g., cooling water) flows through this cooling pipe 236. The temperature of the coolant is transmitted to the cooling pipe 236, the cover 212, and the disc-shaped components 223, thereby maintaining the temperature of the cooling portion 233 at a certain level.

[0158] That is, the cooling pipe 236, the cover 212, and the gaskets 231 of each disk-shaped part 223 are assembled to the cooling well 13 in a state of being in efficient heat transfer contact with each other. The heat of the cooling pipe 236 is transferred and conducted to the cooling portion 233 of each disk-shaped part 223 via the cover 212 and the gaskets 231.

[0159] Figure 6 The path of the gas flowing within the cooling trap 13 is schematically shown by multiple arrows C (bold lines). Within the cooling trap 13, the gas exhausted from the first vacuum pump 11 (hereinafter referred to as "exhaust gas") is introduced into the suction port 214 via the suction-side piping 215. Furthermore, the exhaust gas is introduced into the deposit transfer space 232, which is spatially connected to the suction port 214.

[0160] The exhaust gas diffuses within the deposit transfer space 232 while contacting the plate surface of the cooling unit 233. Furthermore, the exhaust gas passes over the area where the rotating shaft 221 is located and reaches the area on the opposite side of the rotating shaft 221. Furthermore, the exhaust gas passes through the transfer hole 234 formed in the cooling unit 233 of the next stage and enters the deposit transfer space 232 of the next stage.

[0161] The exhaust gas then flows through the deposit transfer space 232, passes through the transfer holes 234, and diffuses into the next deposit transfer space 232. The exhaust gas reaching the exhaust holes 217 of the cover 212 is then guided outside the cooling trap 13 through the exhaust port 203.

[0162] Furthermore, within the cooling trap 13, the exhaust gas contacts the cooling section 233, exchanging heat between the exhaust gas and the cooling section 233. Furthermore, the exhaust gas temperature is lowered by the cooling section 233, causing components in the exhaust gas to solidify, forming deposits. The rotating scraper 222 strikes the resulting deposits, forcibly separating them from the disc-shaped part 223. The disc-shaped part 223 then breaks the deposits into chunks or powder.

[0163] Figure 9 The function of the cooling trap 13 is represented using a semi-logarithmic graph. Figure 9 In the graph, the horizontal axis represents temperature [°C], and the vertical axis represents pressure [Torr]. Figure 9 The symbol F in FIG. 1 represents the sublimation curve of the exhaust gas components. The upper side of the sublimation curve F corresponds to the region where the exhaust gas components are "SOLID" (solid), and the lower side of the sublimation curve F corresponds to the region where the exhaust gas components are "GAS" (gas).

[0164] and then, Figure 9 The symbol P1 in the figure represents the process conditions. These process conditions refer to the environmental conditions (process conditions) when a predetermined process using a process gas is being performed in the equipment (not shown) being evacuated by the first vacuum pump 11 (turbomolecular pump 100). Here, the temperature is 100°C and the pressure is 1 Torr. Furthermore, point P1 is located in the "SOLID" region, indicating that deposits due to components in the process gas are generated under these process conditions.

[0165] then, Figure 9 The symbol P2 in the figure represents the cleaning conditions. These cleaning conditions refer to the conditions for cleaning the deposits that have formed. Here, the cleaning conditions are a temperature of 130°C and a pressure of 0.1 Torr. Furthermore, point P2 is located in the "GAS" region, and under these cleaning conditions, the deposits vaporize.

[0166] then, Figure 9 The symbol P3 in the figure represents the trap condition. This trap condition refers to the conditions that cause deposits to form in the cooling trap 13. Here, the trap temperature is 70°C, and the pressure is 0.1 Torr, the same as the clean condition. Furthermore, point P3 is located in the "SOLID" region, and deposits are generated by subjecting the gas (exhaust gas) to the trap condition environment.

[0167] Cooling (P3) of the exhaust gas by the cooling trap 13 is performed after cleaning (P2). Figure 9In the example shown in FIG2 , after cleaning (P2), the exhaust gas temperature is lowered by cooling trap 13, and components in the exhaust gas that could become deposits (also referred to as "sublimated components" or "deposited components") are actively solidified in cooling trap 13. Consequently, the exhaust gas flowing from first vacuum pump 11 to second vacuum pump 16 is gas free of sublimated components, preventing deposits from adhering to the gas path between first vacuum pump 11A and second vacuum pump 16, and to the gas flow path within second vacuum pump 16.

[0168] Here, Figure 9 The temperature and pressure of cleaning conditions P2 and well conditions P3 are merely examples and can be varied in accordance with the sublimation curve F and process conditions P1. However, cleaning conditions P2 and well conditions P3 must be set so that cleaning conditions P2 are in the "GAS" region and well conditions P3 are in the "SOLID" region.

[0169] According to the vacuum exhaust system cleaning device 10 described above, the cooling trap 13 is provided. This cooling trap 13 is cooled to a temperature below the sublimation temperature of the sublimated components of the gas. Therefore, the cooling trap 13 can actively prevent the formation of deposits on the gas exhausted from the first vacuum pump 11. Furthermore, as described above, deposits can be prevented from adhering to the piping downstream of the cooling trap 13 and the second vacuum pump 16.

[0170] Furthermore, the provision of the switching valve 12 and the third pipe 23 allows, during processes such as semiconductor manufacturing, for example, exhaust gas to flow toward the third pipe 23, bypassing the cooling trap 13 and being directed toward the second vacuum pump 16. This prevents the cooling trap 13 and the like from becoming an obstacle to the flow of gas (also referred to as "flow resistance," "exhaust resistance," etc.).

[0171] Furthermore, since the cooling well 13 includes the disk-shaped component 223 and the cooling pipe 236 in the housing 201 , the disk-shaped component 223 can be cooled satisfactorily, and deposits can be efficiently generated in the cooling well 13 .

[0172] Furthermore, the cooling trap 13 is constructed by stacking multiple disc-shaped parts 223 provided with transfer holes 234 with the transfer holes 234 shifted in phase, so that deposits generated on the disc-shaped parts 223 can be fed (or discharged) to the next stage through the transfer holes 234 .

[0173] The cooling trap 13 also includes a rotating shaft 221 disposed within the housing 201 and a scraper 222 fixed to the rotating shaft 221. The scraper 222 is configured to rotate along the surface of the disk-shaped member 223. Therefore, the scraper 222 can scrape out deposits generated on the disk-shaped member 223. Furthermore, the scraper 222 can transport the deposits to the next stage via the transfer hole 234.

[0174] Furthermore, since there is a branch pipe 24 arranged in the second piping 22, an on-off valve 14 arranged in the branch pipe 24, and a deposit recovery container 15 arranged downstream of the on-off valve 14, the deposits generated in the cooling trap 13 can be sent to the deposit recovery container 15 via the branch pipe 24 and the on-off valve 14.

[0175] In addition, the shell 201 is provided with an exhaust hole 217 and an exhaust port 203 arranged in the cooling trap 13, the on-off valve 14 is arranged downstream of the exhaust hole 217 and the exhaust port 203, and the deposit recovery container 15 is arranged downstream of the on-off valve 14, so that the deposits generated in the shell 201 can be sent to the deposit recovery container 15 through the exhaust hole 217, the exhaust port 203, and the on-off valve 14.

[0176] The present invention is not limited to the above-described embodiment and is capable of various modifications. For example, the switching valve 12 and the third pipe 23 may be omitted, so that the exhaust gas from the first vacuum pump 11 does not bypass the third pipe 23. However, in this case, as previously mentioned, the cooling trap 13 becomes an exhaust resistance during processes such as semiconductor manufacturing. Therefore, the inclusion of the switching valve 12 and the third pipe 23 allows for more efficient exhaust than their absence.

[0177] Furthermore, in the cooling trap 13 , it is considered that by increasing the rotation speed of the scraper 222 and rotating the scraper 222 forward and reversely to stir and crush the deposit, the deposit can be easily transferred to the exhaust port 203 side.

[0178] The shape of each scraping portion 222 is not limited to a rod shape, and can be variously modified, for example, into a plate shape or a shape having a polygonal (pentagonal, hexagonal, octagonal, etc.) cross section.

[0179] Furthermore, although two scraping parts 222 are formed on one stage, the present invention is not limited thereto and one or three or more scraping parts may be formed on one stage. In this case, it is desirable to determine the arrangement of the scraping parts 222 in each group and the whole in consideration of the overall balance during rotation.

[0180] Furthermore, in the cooling trap 13 described above, the number of scrapers 222 is reduced to two per stage, so that the scrapers 222 can be prevented from causing excessive exhaust resistance to the exhaust gas flowing through each deposit transfer space 232 .

[0181] Furthermore, the number of transfer holes 234 is one for each disc-shaped component 223, but this is not limiting. The number of transfer holes 234 may be two or more. Furthermore, the opening area of ​​the transfer holes 234 may be set as large as possible. Furthermore, by increasing the opening area of ​​the transfer holes 234, the deposited material can be efficiently fed to the next stage.

[0182] However, increasing the opening area of ​​the transfer holes 234 reduces the area (cooling area) that can be cooled by the cooling portion 233 in the disk-shaped component 223. Therefore, the number and opening area of ​​the transfer holes 234 (the total opening area if there are multiple transfer holes 234) are preferably such that the exhaust gas contacts the plate surface of the disk-shaped component 223 for a sufficiently long time to achieve satisfactory cooling.

[0183] In the first embodiment, exhaust gas is introduced from above into the cooling trap 13 and deposits are discharged from below, but the present invention is not limited thereto. For example, although not shown in the figure, a structure may be employed in which exhaust gas is received horizontally into the cooling trap.

[0184] Although not shown in the figure, if a structure is adopted in the cooling trap, such as a screw groove formed on a rotating body rotating about a horizontal axis, and the deposit is pushed out by the screw groove, the deposit can be transferred horizontally and discharged. However, by transferring the deposit from the top to the bottom as described above, the deposit can be easily transferred by its own weight, which can simplify the structure of the cooling trap.

[0185] Furthermore, the present invention can adopt various embodiments described below. In addition, the same reference numerals are attached to the same configurations as those in the first embodiment, and their descriptions are omitted as appropriate.

[0186] For example, Figure 10 A cleaning device 240 of a vacuum exhaust system according to a second embodiment of the present invention is schematically shown. The cleaning device 240 of the second embodiment is a type of device that includes two vacuum exhaust systems similar to those of the first embodiment in parallel.

[0187] like Figure 10 As shown, a first vacuum pump 11A and a second vacuum pump 16A are provided in a vacuum exhaust system (hereinafter referred to as the "first exhaust system") 241 on one side (the left side in the figure). Furthermore, a first vacuum pump 11B and a second vacuum pump 16B are provided in a vacuum exhaust system (hereinafter referred to as the "second exhaust system") 242 on the other side (the right side in the figure).

[0188] Among them, in the first exhaust system 241 as one of the vacuum exhaust systems, the cleaning device 10 ( Figure 1 ) Similarly, the apparatus includes a first vacuum pump 11A, a switching valve 12A, a cooling trap 13, an on-off valve 14, a deposit recovery container 15, and a second vacuum pump 16A.

[0189] The first vacuum pump 11A and the cooling trap 13 are connected via a first pipe 21A, with a switching valve 12A disposed midway along the first pipe 21A. The cooling trap 13 and the second vacuum pump 16A are connected via a second pipe 22A. Furthermore, the second pipe 22A is connected to the deposit recovery container 15 via a branch pipe 24, with an on-off valve 14 disposed midway along the branch pipe 24. Furthermore, the switching valve 12A and the second pipe 22A are connected via a third pipe 23A.

[0190] As these devices, the cleaning device 10 ( Figure 1 ) has the same configuration as that of the first vacuum pump 11, switching valve 12, cooling trap 13, on-off valve 14, deposit recovery container 15, and second vacuum pump 16. Furthermore, as the first vacuum pump 11A, the same turbomolecular pump 100 as in the first embodiment can be used.

[0191] Furthermore, as the first pipe 21A, the second pipe 22A, the third pipe 23A, and the branch pipe 24, the cleaning device 10 ( Figure 1 ) are the same components as the first pipe 21, the second pipe 22, the third pipe 23, and the branch pipe 24. In addition, the fourth pipe 25 is connected to the suction side of the first vacuum pump 11A. As this fourth pipe 25, the same structure as the first embodiment can be adopted.

[0192] Furthermore, the first exhaust system 241, like the first embodiment, has a cleaning function. By heating the gas in the first vacuum pump 11A (or a portion of the first piping 21A), deposits can be vaporized. The heated gas is then cooled in the cooling trap 13, and the resulting deposits are recovered in the deposit recovery container 15, similar to the first embodiment.

[0193] Therefore, similar to the first embodiment described above, sublimated components that could become deposits can be removed from the exhaust gas flowing from the first vacuum pump 11A to the second vacuum pump 16. Furthermore, deposits can be prevented from adhering to the gas path between the first vacuum pump 11A and the second vacuum pump 16, and to the gas flow path within the second vacuum pump 16.

[0194] Next, the first pipe 21B of the second exhaust system 242 is connected to the first pipe 21A in the first exhaust system 241. The second exhaust system 242 includes the first vacuum pump 11B and the second vacuum pump 16B. The first vacuum pump 11B is further connected to the cooling trap 13 via the first pipe 21B.

[0195] A switching valve 12B is located midway along the first pipe 21B. This is similar to the first exhaust system 241, but the second exhaust system 242 does not have the second vacuum pump 16B connected downstream of the cooling trap 13. Furthermore, in the second exhaust system 242, a third pipe 23B connected to the switching valve 12B extends to the second vacuum pump 16B.

[0196] The second exhaust system 242 has the same cleaning function as the first exhaust system 241, and can vaporize deposits by heating the gas. The heated gas flows through the first pipe 21B via the switching valve 12B and into the first pipe 21A of the first exhaust system 241.

[0197] The gas (exhaust gas) flowing into the first pipe 21A is cooled in the cooling trap 13, and the resulting deposits are recovered in the deposit recovery container 15. The exhaust gas, from which sublimated components that could become deposits have been removed, then flows to the second vacuum pump 16A through the exhaust action of the second vacuum pump 16A of the first exhaust system 241 and is discharged from the second vacuum pump 16A.

[0198] According to the cleaning device 240 of the second embodiment, while achieving the same inventive effects as the first embodiment, it can also include multiple exhaust systems (here, a first exhaust system 241 and a second exhaust system 242). Furthermore, the multiple exhaust systems can also serve as cooling traps 13 and deposit recovery containers 15. Therefore, the number of cooling traps 13 and other components in the multiple (here, two) exhaust systems can be reduced, simplifying the exhaust gas cleaning structure.

[0199] Then, based on Figure 11 A cleaning device 250 for a vacuum exhaust system according to a third embodiment of the present invention will be described. Components identical to those in the aforementioned embodiments are denoted by the same reference numerals, and their descriptions will be omitted as appropriate.

[0200] The cleaning device 250 according to the third embodiment is similar to the cleaning device 240 according to the second embodiment in that it has two exhaust systems (a first exhaust system 241 and a second exhaust system 242). However, in the cleaning device 250 according to the third embodiment, the second pipe 22 of the first exhaust system 241 branches toward the second exhaust system 242 at a location 257 where it merges with the third pipe 23A, and then extends to the third pipe 23B in the second exhaust system 242.

[0201] That is, in the cleaning apparatus 240 according to the second embodiment, of the second vacuum pumps 16A and 16B, only the second vacuum pump 16A of the first exhaust system 241 is connected to the downstream side of the cooling trap 13. In contrast, in the cleaning apparatus 250 according to the third embodiment, the second vacuum pump 16B of the second exhaust system 242 is also connected to the downstream side of the cooling trap 13 via the extension 22B of the second pipe 22 in the first exhaust system 241 and the third pipe 23B.

[0202] According to the cleaning device 250 of the third embodiment, in addition to achieving the same inventive effects as the first embodiment, the second vacuum pump 16B of the second exhaust system 242 can also be used to exhaust the gas cooled by the cooling trap 13, thereby improving the overall exhaust capacity of the cleaning device 250.

[0203] Here, in the cleaning apparatus 250 of the third embodiment, the portion of the third pipe 23B of the second exhaust system 242 from the confluence 258 with the extension 22B to the downstream side (the side connected to the second vacuum pump 16B) can be classified together with the extension 22B as the second pipe in the second exhaust system 242. Furthermore, in the cleaning apparatus 250 of the third embodiment, it is also conceivable that the first exhaust system 241 and the second exhaust system 242 may partially share the second pipe.

[0204] Then, based on Figure 12 A cleaning device 260 for a vacuum exhaust system according to a fourth embodiment of the present invention will be described. Components identical to those in the aforementioned embodiments are denoted by the same reference numerals, and their description will be omitted.

[0205] The cleaning apparatus 260 of the fourth embodiment is similar to the cleaning apparatus 240 of the second embodiment and the cleaning apparatus 250 of the third embodiment in that it includes two exhaust systems (a first exhaust system 241 and a second exhaust system 242). However, in the cleaning apparatus 260 of the fourth embodiment, the first exhaust system 241 and the second exhaust system 242 share a single second vacuum pump 16C.

[0206] Furthermore, in the cleaning apparatus 260 according to the fourth embodiment, the third pipe 23A of the first exhaust system 241 and the third pipe 23B of the second exhaust system 242 merge midway, and the single common pipe 261 is connected to the second vacuum pump 16C. Furthermore, the second pipe 22A of the first exhaust system 241 merges with the common pipe 261, and exhaust gases from both the first exhaust system 241 and the second exhaust system 242 pass through the cooling trap 13 and are exhausted by the second vacuum pump 16C.

[0207] According to the cleaning device 250 of the fourth embodiment, in addition to achieving the same effects of the invention as the first embodiment, the number of second vacuum pumps (16C) and the like can be suppressed in multiple (here two) exhaust systems, and the cleaning structure of the exhaust gas can be simplified.

[0208] Here, in the cleaning device 260 described in the fourth embodiment, a second vacuum pump 16C is shared by the first exhaust system 241 and the second exhaust system 242, so as the second vacuum pump 16C, it is considered desirable to use a larger pump (a large flow pump, etc.) than the various second vacuum pumps 16, 16A, 16B used in the first to third embodiments.

[0209] The above describes various embodiments of the present invention, but the present invention is not limited to these embodiments and can be modified in various ways. For example, the first vacuum pump 11 (11A, 11B) is connected to the cooling trap 13 via the first pipe 21 (21A, 21B), but the present invention is not limited to this. For example, the cooling trap 13 may be directly connected to the exhaust port 133 ( Figure 2 ).

[0210] In this case, consider the exhaust port 133 ( Figure 2 ) is connected to the air intake side piping 215 of the cooling trap 13, is connected to the air intake hole 214 of the cooling trap 13, etc.

[0211] Furthermore, a cooling pipe 236 is used to cool the disc-shaped component 223 in the cooling well 13. However, this is not a limitation and various conventional cooling means can be used. For example, a Peltier element (not shown) can be used as the cooling means, and the power supply to the Peltier element can be controlled to manage the temperature in the cooling well 13.

[0212] Furthermore, the valve devices in the cleaning devices 10 , 240 , 250 , and 260 are not limited to the switching valves 12 , 12A, and 12B and the on-off valve 14 , and valve devices having necessary functions can be added as appropriate.

Claims

1. A cleaning device for a vacuum exhaust system, The vacuum exhaust system comprises: A cooling trap, which cools the gas containing sublimated components to produce deposits; at least one first vacuum pump, disposed upstream of the cooling trap; at least one first exhaust path connecting the first vacuum pump and the cooling trap; at least one second vacuum pump disposed downstream of the cooling trap; as well as at least one second exhaust path connecting the second vacuum pump and the cooling trap, Exhaust the aforementioned gas, The cleaning device of the vacuum exhaust system is characterized in that: heating at least the first vacuum pump or a portion of the first exhaust path to a temperature above the sublimation temperature of the sublimated component and cooling the cooling trap to a temperature below the sublimation temperature of the sublimated component, The cooling trap has: A housing having an air intake port and an air exhaust port, at least one plate-shaped portion disposed in the housing, A cooling mechanism for cooling the plate-like portion, A rotating shaft provided in the housing, a scraper fixed to at least one of the rotating shafts; The scraper portion is configured to be rotatable along the plate surface of the plate-shaped portion.

2. The cleaning device for the vacuum exhaust system according to claim 1, characterized in that: The exhaust path includes a switching valve provided in at least one of the first exhaust paths, and a third exhaust path connecting the switching valve and at least one of the second exhaust paths.

3. The cleaning device for the vacuum exhaust system according to claim 1, characterized in that: The cooling well is formed by stacking a plurality of the plate-like portions each having at least one opening with the openings being arranged in a phase-shifted manner.

4. The cleaning device for a vacuum exhaust system according to any one of claims 1 to 3, characterized in that: The exhaust gas recovery device includes a branch path provided in the second exhaust path, an on-off valve provided in the branch path, and a deposit recovery container provided downstream of the on-off valve.

5. The cleaning device for the vacuum exhaust system according to claim 3, characterized in that: The cooling trap includes a deposit discharge port provided in the housing of the cooling trap, an on-off valve disposed downstream of the deposit discharge port, and a deposit recovery container disposed downstream of the on-off valve.

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