JP7564151B2 - Vacuum pumps and vacuum exhaust systems - Google Patents

Description

The present invention relates to vacuum pumps, such as turbomolecular pumps, and vacuum evacuation systems.

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

In addition, in the case of exhaust vacuum pumps for manufacturing equipment for semiconductors and flat panels (hereafter referred to as "semiconductors, etc."), reaction products generated during the manufacturing process of semiconductors, etc. may accumulate inside the vacuum pump. For example, the following techniques are known as countermeasures against deposits.

JP 2005-171766 A JP 2020-063737 A JP 2021-042722 A JP 2021-179193 A

The invention disclosed in Patent Document 1 introduces into the pump an inert gas (gas ballast gas) heated to a higher temperature than the gas (condensable or coagulable gas) flowing inside the pump. The invention disclosed in Patent Document 1 has the effect of preventing the accumulation of reaction products inside the pump by diluting the reaction products with the inert gas. However, in the case of a turbomolecular pump, if a large amount of heated gas is supplied into the pump, the inside of the pump will quickly overheat. For this reason, the turbomolecular pump cannot supply gas with a sufficient flow rate or heat, and it is considered that even if a technology similar to the invention disclosed in Patent Document 1 is adopted, a sufficient effect of preventing accumulation can not be obtained. Moreover, Patent Document 1 discloses a technology to prevent the accumulation of reaction products, but not a technology to remove internal deposits.

The invention disclosed in Patent Document 2 is believed to have the effect of blowing away deposits inside the pump by injecting a pulse of gas at a specified flow rate into the pump. However, it is believed to be difficult for the invention disclosed in Patent Document 2 to remove deposits that are firmly attached to the walls inside the pump or that are located away from the nozzle that ejects the gas.

The invention disclosed in Patent Document 3 provides a heater (temperature raising means) to heat the inside of the vacuum pump. However, in the invention disclosed in Patent Document 3, it takes a long time to heat the deposit to the sublimation temperature.

The invention disclosed in Patent Document 4 introduces an inert gas at a temperature equal to or higher than the sublimation temperature into the vacuum pump. However, the invention disclosed in Patent Document 4 is intended to prevent the formation of deposits, and is not intended to remove any deposits that do form.

The object of the present invention is to provide a vacuum pump and a vacuum exhaust system capable of removing deposits using a large amount of high-temperature fluid.

(1) In order to achieve the above object, the vacuum pump according to the present invention comprises:
a fluid heating means for heating the fluid to a temperature above the sublimation temperature of the deposit ;
A fluid inlet that is an inlet for the fluid;
and a flow control means for controlling the flow of the fluid,
The flow control means
The present invention is characterized in that the flow of the fluid is controlled so that the fluid is supplied into the vacuum pump at a flow rate exceeding the maximum flow rate that can be exhausted during rated operation while the vacuum pump is stopped or operating at a low speed.
(2) In order to achieve the above object, the vacuum pumping system according to the present invention comprises:
a fluid heating means for heating the fluid to a temperature above the sublimation temperature of the deposit ;
a vacuum pump having a fluid inlet for the fluid;
and a flow control means for controlling the flow of the fluid,
The flow control means
The present invention is characterized in that the flow of the fluid is controlled so that the fluid is supplied into the vacuum pump at a flow rate exceeding the maximum flow rate that can be exhausted during rated operation while the vacuum pump is stopped or operating at a low speed.

The above invention provides a vacuum pump and a vacuum exhaust system capable of removing deposits using a large amount of high-temperature fluid.

1 is an explanatory diagram illustrating a schematic configuration of a vacuum pump and a vacuum evacuation system according to a first embodiment of the present invention; FIG. 2 is a circuit diagram of an amplifier circuit. 6 is a time chart showing control when a current command value is larger than a detection value. 6 is a time chart showing control when a current command value is smaller than a detection value. FIG. 2 is an explanatory diagram illustrating a flow of a heating fluid in the vacuum pump and the vacuum evacuation system according to the first embodiment. FIG. 11 is an explanatory diagram illustrating a flow of a heating fluid in a vacuum pump and a vacuum evacuation system according to a second embodiment of the present invention. FIG. 11 is an explanatory diagram illustrating a flow of a heating fluid in a first fluid transfer means (flow path A) of a vacuum pump and a vacuum evacuation system according to a third embodiment of the present invention. FIG. 11 is an explanatory diagram illustrating a flow of a heating fluid in a second fluid transfer means (flow path B) of a vacuum pump and a vacuum evacuation system according to a third embodiment of the present invention. FIG. 2 is an explanatory diagram illustrating a flow of a heating fluid in the vacuum pump and the vacuum evacuation system according to the first embodiment of the present invention. FIG. 11 is an explanatory diagram illustrating a flow of a heating fluid in a vacuum pump and a vacuum evacuation system according to a fourth embodiment of the present invention. FIG. 13 is an explanatory diagram illustrating a flow of a heating fluid in a vacuum pump and a vacuum evacuation system according to a fifth embodiment of the present invention.

First Embodiment
A vacuum pump according to a first embodiment of the present invention will be described below with reference to the drawings. Fig. 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.

<<Basic Configuration of Turbomolecular Pump 100>>
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 tube 127. Inside the outer tube 127, a rotor 103 is provided, the rotor 103 having a plurality of rotors 102 (102a, 102b, 102c, ...) which are turbine blades for sucking in and exhausting gas, formed radially on its periphery in multiple stages. A rotor shaft 113 is attached to the center of the rotor 103, and the rotor shaft 113 is supported in the air and its position is controlled by, for example, a five-axis controlled magnetic bearing.

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

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 the position signal detected by the upper radial sensor 107, and the amplifier circuit 150 (described later) shown in FIG. 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.

The rotor shaft 113 is made of a material with high magnetic permeability (iron, stainless steel, etc.) and is attracted by the magnetic force of the upper radial electromagnet 104. Such adjustment is performed independently in the X-axis direction and the Y-axis direction. The lower radial electromagnet 105 and the lower radial sensor 108 are arranged in the same manner as the upper radial electromagnet 104 and the upper radial sensor 107, and adjust the lower radial position of the rotor shaft 113 in the same manner as the upper radial position.

Furthermore, the 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 the rotor shaft 113. The 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 the rotor shaft 113, and the axial position signal is sent to the control device 200.

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 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.

In this way, the control device 200 appropriately adjusts the magnetic force 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.

On the other hand, the motor 121 has multiple magnetic poles arranged circumferentially to surround the rotor shaft 113. Each magnetic pole is controlled by the control device 200 so as to rotate the rotor shaft 113 via electromagnetic forces acting between the magnetic poles and the rotor shaft 113. In addition, the motor 121 incorporates a rotational speed sensor, such as a Hall element, resolver, or encoder (not shown), and the rotational speed of the rotor shaft 113 is detected by the detection signal of this rotational speed sensor.

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

Multiple fixed blades 123 (123a, 123b, 123c...) are arranged with a small gap (predetermined interval) between the rotor blades 102 (102a, 102b, 102c...). The rotor blades 102 (102a, 102b, 102c...) are formed at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113 in order to transport exhaust gas molecules downward by collision.

The fixed blades 123 are also 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 rotor blades 102 toward the inside of the outer cylinder 127. The outer peripheral end of the fixed blades 123 is supported by being inserted between a plurality of stacked fixed blade spacers 125 (125a, 125b, 125c, ...).

The fixed wing spacer 125 is a ring-shaped member, and is made of metals such as aluminum, iron, stainless steel, copper, or alloys containing these metals as components. An outer cylinder 127 is fixed to the outer periphery of the fixed wing spacer 125 with a small gap 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 is connected to 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.

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

The base portion 129 is a disk-shaped member 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 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.

In this configuration, when the rotor 102 is rotated together with the rotor shaft 113 by the motor 121, the rotor 102 and the fixed blades 123 act to draw exhaust gas 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 fixed blades 123 and is transferred to the base portion 129. At this time, the temperature of the rotor 102 rises due to frictional heat generated when the exhaust gas comes into contact with the rotor 102 and conduction of heat generated by the motor 121, but this heat is transferred to the fixed blades 123 side by radiation or conduction by gas molecules (gas molecules) of the exhaust gas.

The fixed blade spacers 125 are joined together at their outer periphery and transmit to the outside heat received by the fixed blades 123 from the rotor blades 102 and frictional heat generated when exhaust gas comes into contact with the fixed blades 123.

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

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

In this case, a purge gas introduction pipe (also called a "purge gas port", not shown) is provided in the base portion 129, and the purge gas is introduced through this pipe. The introduced purge gas is sent to the exhaust port 133 through gaps between the protective bearing 120 and the rotor shaft 113, between the rotor and stator of the motor 121, between the stator column 122 and the inner cylindrical portion of the rotor 102 (lower cylindrical portion 103b of the rotor) and between the base portion 129.

The turbomolecular pump 100 requires control based on the model identification and individually adjusted unique parameters (for example, various characteristics corresponding to the model). To store these control parameters, the turbomolecular pump 100 has an electronic circuit section 141 in its main body. The electronic circuit section 141 is composed of a semiconductor memory such as an EEP-ROM, 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 the base section 129 that constitutes the lower part of the turbomolecular pump 100, and is closed by an airtight bottom cover 145.

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

For example, when SiCl ₄ is used as a process gas in an Al etching apparatus, at low vacuum (760 [torr] to 10 ⁻² [torr]) and low temperature (about 20° C.), a solid product (e.g., AlCl ₃ ) precipitates and adheres to and accumulates inside the turbomolecular pump 100, as can be seen from the vapor pressure curve. When precipitates of the process gas accumulate inside the turbomolecular pump 100, the deposits narrow the pump flow path, causing a decrease in the performance of the turbomolecular pump 100. The above-mentioned product is prone to solidification and adhesion in high pressure areas near the exhaust port and near the threaded spacer 131.

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

Next, regarding the turbomolecular pump 100 configured in this manner, we will explain 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. A circuit diagram of this amplifier circuit is shown in Figure 2.

In FIG. 2, one end of the electromagnet winding 151 constituting the upper radial electromagnet 104 etc. is connected to the positive pole 171a of the power supply 171 via the transistor 161, and the other end is connected to the negative pole 171b of the power supply 171 via the current detection circuit 181 and the 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.

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

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

The amplifier circuit 150 configured as above corresponds to one electromagnet. Therefore, if the magnetic bearing is controlled on 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.

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

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. Then, based on the result of this comparison, it determines the size of the pulse width (pulse width times Tp1, Tp2) to be generated within a control cycle Ts, which is one period of PWM control. As a result, gate drive signals 191a, 191b having this pulse width are output from the amplifier control circuit 191 to the gate terminals of transistors 161, 162.

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

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

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

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 equivalent to pulse width time Tp1 only once during control cycle Ts (e.g., 100 μs) as shown in FIG. 3. Therefore, during this period, electromagnet current iL increases toward current value iLmax (not shown) that can flow from positive pole 171a to negative pole 171b via transistors 161 and 162.

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 equivalent to pulse width time Tp2 only once during control cycle Ts, as shown in FIG. 4. Therefore, during this period, the electromagnet current iL decreases from negative pole 171b to positive pole 171a toward a current value iLmin (not shown) that can be regenerated via diodes 165 and 166.

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

The turbomolecular pump 100 having such a basic configuration has an intake section connected to the target device on the upper side in FIG. 1 (the side of the intake port 101), and an exhaust section connected to an auxiliary pump (back pump) (not shown) on 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 side in the figure). The turbomolecular pump 100 can be used not only in the vertical position shown in FIG. 1, but also in an inverted position, horizontal position, or inclined position.

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

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

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

For example, a purge gas port (not shown) extending linearly in the radial direction is provided at a predetermined location of the base portion 129 (such as a position approximately 180 degrees away from the exhaust port 133). Purge gas is then supplied to this purge gas port 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).

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

In addition, in Figure 1, which shows the structure of the turbomolecular pump 100 and the rotor 103, hatching showing cross sections of parts has been omitted to avoid cluttering the drawing.

<<Vaporization of deposits by hot air>>
As described above, deposits of the process gas may accumulate inside the turbo molecular pump 100. In the first embodiment, a high-temperature fluid (e.g., hot air of about 200° C., or a high-temperature purge gas) is introduced (supplied) into the turbo molecular pump 100. The hot air comes into contact with the deposits, heats them, and vaporizes them.

In FIG. 1, reference numeral 210 denotes a hot air generator, and reference numeral 212 denotes a valve device. A heating fluid inlet port 214, which is a tubular flange part, is fixed to the outer cylinder 127 of the turbomolecular pump 100. The heating fluid inlet port 214 constitutes a fluid inlet (heating fluid inlet) 216 for the heating fluid. Here, the heating fluid is also called a "heating purge gas." As described later, the heating purge gas differs from the purge gas, which is the protective gas described above, in that it is heated by the hot air generator 210 to vaporize the deposits. On the other hand, the heating purge gas may be the protective gas described above, which is heated and used.

The heating fluid introduction port 214 protrudes radially from the outer cylinder 127. A valve device 212 is connected to the tip of the heating fluid introduction port 214, and a hot air generator 210 is connected to the valve device 212. Here, in each embodiment, the flange parts are airtightly connected to each other via the flanges, but in each figure, the flange parts are shown separated from each other to clearly show the boundaries of the flange parts.

Inside the outer cylinder 127, a space that serves as the heating fluid inlet 217 is formed in a ring shape. The heating fluid inlet 217 is located at the boundary between the turbomolecular pump mechanism and the thread groove pump mechanism (Holbeck type exhaust mechanism 204). As described above, the turbomolecular pump mechanism is composed of the rotor 102, the fixed blades 123, etc. The thread groove pump mechanism is composed of the rotor lower cylindrical portion 103b, the threaded spacer 131, etc. The heating fluid inlet 217 is spatially connected to the heating fluid inlet 216 of the heating fluid inlet port 214.

The hot air generator 210 is of the dryer type and has a built-in fan section and heater section (not shown). For example, a hot wire such as a nichrome wire can be used for the heater section. The hot air generator 210 rotates the fan section (not shown) to take in an external heating fluid and cause it to flow. Examples of the external heating fluid include air at room temperature (dry air) and inert gas (N2 gas, etc.). In the hot air generator 210, the heater section is energized to generate heat. The hot air generator 210 passes the heating fluid through the heater section, raising the temperature of the heating fluid and generating a high-temperature fluid. Hereinafter, the heated heating fluid may be referred to as a "high-temperature fluid."

The hot air generator 210 may be controlled by the control device 200 (Figure 1), or may be controlled by a control device other than the control device 200 (hot air generator control device, not shown).

Although not shown, the hot air generator 210 may be connected to an external fan device and heat the fluid sent from the fan device with a built-in heater (not shown). The hot air generator 210 may be connected to a pressure pump or a high-pressure gas cylinder, etc., and the heating fluid may be supplied from the pressure pump or the high-pressure gas cylinder (e.g., an N2 gas cylinder).

The fluid heated by the hot air generator 210 becomes hot air (high-temperature fluid) and flows out of the hot air generator 210 toward the valve device 212. The valve device 212 is an ON/OFF type, and is controlled to open and close the flow path of the high-temperature fluid. The opening and closing of the valve device 212 may be controlled by the control device 200 (Figure 1), or a control device other than the control device 200 (valve control device, not shown) may be provided and may be controlled by this control device.

Figure 5 shows the flow path of the heating fluid in the turbomolecular pump 100 of the first embodiment with arrows A to E. When the valve device 212 is controlled to be in an open state, the heating fluid passes through the valve device 212 and the heating fluid inlet port 214 as shown by arrow A, and is introduced into the heating fluid inlet section 217 located inside the outer cylinder 127 as shown by arrow B.

As shown by arrow C, a part of the heating fluid introduced into the outer cylinder 127 flows in a ring shape (also called a "cylindrical shape") in the circumferential direction of the outer cylinder 127, and also flows on the opposite side of the outer cylinder 127 (the side separated by 180 degrees). Although not shown in FIG. 5, the heating fluid (high-temperature fluid) also flows around to the back side of the side shown in FIG. 5 (also called the "side not shown" or the "side hidden in FIG. 5"). In addition, as shown by arrow D, a part of the high-temperature fluid introduced into the outer cylinder 127 also flows in the axial direction of the turbomolecular pump 100 through the Holweck-type exhaust mechanism 204. In this way, the heating fluid flows inside the turbomolecular pump 100, and the inside of the turbomolecular pump 100 is heated.

The high-temperature fluid that flows inside the outer cylinder 127 reaches the exhaust port 133 and is discharged to the outside of the outer cylinder 127 through the exhaust port 133 as shown by the arrow E. In the example of FIG. 5 (and FIG. 1), the exhaust port 133 is used not only to exhaust the exhaust gas but also to discharge the high-temperature fluid.

Here, a space that serves as the heating fluid outlet section 218 is formed in front of (upstream of) the exhaust port 133. The heating fluid outlet section 218 is spatially connected to the exhaust port 133, and the exhaust gas and high-temperature fluid are discharged to the outside of the outer cylinder 127 via the heating fluid outlet section 218 and the exhaust port 133.

As mentioned above, an auxiliary pump (back pump) (not shown) is connected to the rear (downstream) of the exhaust port 133, and the auxiliary pump operates even while the high-temperature fluid is being introduced. Although not shown, a valve device (e.g., an ON/OFF type, indicated by reference numeral 390 in FIG. 9) is provided between the exhaust port 133 and the auxiliary pump, and is controlled to open and close the flow path of the high-temperature fluid. The opening and closing control of this valve device (indicated by reference numeral 390 in FIG. 9) may also be performed by the control device 200 (FIG. 1), or a control device (valve control device, not shown) other than the control device 200 may be provided and performed by this control device. Furthermore, the valve device on the outlet side (indicated by reference numeral 390 in FIG. 9) may be controlled by a control device common to the inlet valve device 212.

The introduction of the high-temperature fluid as described above is performed when the process gas (exhaust gas) is not being exhausted. Furthermore, the introduction of the high-temperature fluid is performed when the turbomolecular pump 100 is stopped (exhaust) or is operating at a low speed. In other words, the introduction of the high-temperature fluid is performed when the turbomolecular pump mechanism including the rotor 102 is not driven (stopped), or when the turbomolecular pump mechanism including the rotor 102 is not rotating at high speed for exhausting the exhaust gas (operating at a low speed). The introduction of the high-temperature fluid may be performed either when the turbomolecular pump 100 is stopped or when it is operating at a low speed, or may be performed both.

The upper speed limit for "low-speed operation" is not necessarily determined uniformly. The upper speed limit for "low-speed operation" can be determined, for example, based on the rotation speed at the rated operation of the turbomolecular pump 100 as a reference (reference rotation speed). Operation at or above the rotation speed at the rated operation of the turbomolecular pump 100 can be defined as "high-speed operation" or "non-low-speed operation", and operation at a rotation speed below the rated operation can be defined as "low-speed operation".

In addition to the above, the reference rotation speed when exhausting exhaust gas can be, for example, the maximum rotation speed or the average rotation speed. In this case, operation at a rotation speed lower than the maximum rotation speed or the average rotation speed can be defined as "low speed operation."

By introducing the high-temperature fluid into the outer cylinder 127, the various components disposed inside the outer cylinder 127 are heated. If the high-temperature fluid is supplied while the turbomolecular pump 100 is operating at high speed (e.g., during rated operation, operation at maximum rotation speed, operation at average rotation speed, etc.), the various components will overheat and the heat load on the various components will increase. However, as in this embodiment, if the high-temperature fluid is supplied while the turbomolecular pump 100 is "stopped" or "operating at low speed", it is possible to prevent the various components from overheating compared to when the turbomolecular pump 100 is rotating at high speed. Preventing the various components from overheating leads to a reduction in the parts costs of the turbomolecular pump 100 and the parts costs related to cleaning the inside of the turbomolecular pump 100.

The "low-speed operation" of the turbomolecular pump 100 and the "overheating" of the components can be considered as follows. For example, if the rotational speed of the motor 121 and the rotor 102 is reduced from tens of thousands of rotations to a few thousand rotations, reducing the rotational speed by one tenth, the amount of heat supplied to the various components is reduced to about one hundredth. Therefore, even if the rotational speed is reduced slightly from a high-speed rotation state, the thermal load acting on the various components can be significantly reduced, and a flow rate several times the maximum flow rate that can be exhausted during rated operation can be exhausted. In addition, a large flow rate can be ensured for the supply of high-temperature fluid. In this way, the specific speed of the "low-speed operation" state can be determined taking into account the thermal load acting on the various components.

Thus, the turbomolecular pump 100 comprises a fluid heating means for heating the fluid, a fluid inlet, and a flow control means for controlling the flow of the fluid, and in the turbomolecular pump 100, the flow control means controls the flow of the fluid so that the fluid is supplied into the turbomolecular pump 100 while the turbomolecular pump 100 is stopped (exhaust) or is operating at a low speed.

The fluid heating means may be any means capable of heating the heating fluid, which is a fluid before it is heated, to a sufficient temperature. The fluid heating means includes at least a part of the hot air generator 210, the heater portion (not shown) of the hot air generator 210, etc. The fluid inlet may be an inlet for the heating fluid (high-temperature fluid). The fluid inlet may include the heating fluid inlet 216, etc.

The flow control means may be any means capable of controlling the flow of the heating fluid or the high-temperature fluid. The flow control means may include, for example, at least a portion of the fan device (not shown) of the hot air generator 210, the control means of the hot air generator 210 (the control device 200 or another control device), the valve device 212, and the control means of the valve device 212 (the control device 200 or another control device).

In the turbomolecular pump 100 of the first embodiment, the fluid transfer means 220 is configured to include at least a portion of the hot air generator 210, the valve device 212, the heating fluid introduction port 214 (constituting the heating fluid inlet 216), the portion in the outer cylinder 127 through which the high-temperature fluid flows, and the exhaust port 15 (constituting the exhaust port 133). The fluid transfer means 220 is capable of supplying fluid to the turbomolecular pump 100. The fluid transfer means 220 can also include an auxiliary pump (back pump, not shown) connected to the exhaust port 133.

The heating fluid inlet 216 formed by the heating fluid introduction port 214 is disposed in a position between the intake port 101 and the exhaust port 133 formed by the exhaust port 15 in the axial direction of the turbomolecular pump 100. The heating fluid inlet 216 is located upstream of the exhaust port 133 in the exhaust direction of the turbomolecular pump 100 (the direction from the upstream side to the downstream side of the exhaust gas). In other words, the heating fluid inlet 216 is disposed upstream of the exhaust port 133 in the path of the exhaust flow of the turbomolecular pump 100.

The turbomolecular pump 100 is equipped with the aforementioned fluid transfer means 220, and can supply the turbomolecular pump 100 with a fluid, for example, about 10 times the maximum flow rate (for example, 2 (L/min)) that can be exhausted during rated operation. The flow rate of the fluid can be set by selecting a hot air generator 210 with sufficient output (capacity).

Here, the maximum flow rate that the turbomolecular pump 100 can exhaust during rated operation is the maximum flow rate of the exhaust gas during rated operation of the turbomolecular pump 100. Specifically, the maximum flow rate of the exhaust gas can be approximately 2000 (sccm; standard cc/min). 2000 (sccm) is equivalent to 2 (L/min). However, according to the inventors' calculations, simply setting the flow rate of the high-temperature fluid for vaporizing the deposits to approximately 2000 (sccm) to match the maximum flow rate of the exhaust gas is insufficient to transfer (supply) a sufficient amount of heat to vaporize the deposits.

Therefore, it is possible to determine the introduction conditions (injection conditions) of the high-temperature fluid as follows. For example, the flow rate at a pressure of 1 atmosphere is set to approximately 100 [L/min] (50 times the above-mentioned exhaust gas flow rate of 2 (L/min)). The temperature of the high-temperature fluid is set to approximately 200 [°C]. The output of the hot air generator 210 for heating the fluid is set to approximately 350 [W: watts].

By determining the conditions for introducing the high-temperature fluid in this way, it is possible to transfer a sufficient amount of heat to vaporize (sublimate) the deposits. The temperature of the high-temperature fluid must be equal to or higher than the sublimation temperature of the component to be vaporized. When performing an estimate under the same conditions with a flow rate of 2 [L/min], the amount of heat that can be introduced into the turbo molecular pump 100 is only about 7 [W].

The amount of heat input of the high temperature fluid can be calculated as follows:
First, the injection conditions are as follows: the gas type is N2 gas, which is an inert gas. The density of N2 gas is 1.176 [kg/ ^m3 ] and the specific heat is 1,034 [J/kgK]. The gas temperature is 200 [℃], the gas flow rate is 100 [L/min] (= 0.00167 [ ^m3 /s]), and the pressure is atmospheric pressure.
Under these implant conditions, the implant mass is calculated as follows:
0.00167[ ^m3 /s] × 1.176 [kg/ ^m3 ] = 0.00196 [kg/s]
The heat input is calculated as follows:
0.00196 [kg/s] × 1,034 [J/kgK] × (200-20) [℃]= 365 [W]
The gas species used for the high temperature fluid may be an inert gas other than N2 gas, or may be a gas other than an inert gas. The gas species used for the high temperature fluid may be a gas used as a cleaning gas.

The turbomolecular pump 100 also has a fluid outlet (here, exhaust port 133). The high-temperature fluid introduced into the outer cylinder 127 from the fluid inlet (here, heating fluid inlet 216) flows inside the outer cylinder 127, raises the temperature (and vaporizes) the deposits, and is then discharged to the outside of the outer cylinder 127 via the fluid outlet (here, exhaust port 133).

According to the turbomolecular pump 100 of the first embodiment described above, deposits can be heated, vaporized, and removed outside the pump by introducing a high-temperature fluid into the turbomolecular pump 100. Since the high-temperature fluid comes into direct contact with the surface of the deposits, the temperature of the deposits begins to rise immediately after the high-temperature fluid is supplied. This eliminates the need to wait for the temperature rise of the components (flow path components) that configure the flow path of the high-temperature fluid, and allows the deposits to be removed efficiently in a short time.

For example, if a heater is used to raise the temperature of the components inside the turbo molecular pump 100 and the deposits are then heated through the heated components, it may take about 1 to 2 hours to raise the temperature of the components sufficiently. However, by raising the temperature of the heating fluid using the dryer-type hot air generator 210, a high-temperature fluid can be generated instantly. This allows the deposits to be removed efficiently in a short time.

Here, the Holweck type exhaust mechanism 204 and its surrounding areas are areas where deposits tend to accumulate. For this reason, as in the turbomolecular pump 100, by determining the positions of the heating fluid inlet 216 and the exhaust port 133 so that the areas where deposits tend to accumulate are located between the heating fluid inlet 216 and the exhaust port 133, it is possible to effectively vaporize the deposits.

The flow of the high-temperature fluid is controlled so that the high-temperature fluid is supplied to the inside of the outer cylinder 127 while the turbomolecular pump 100 is stopped (exhaust) or operating at a low speed. This allows a large amount of high-temperature fluid to be introduced into the inside of the outer cylinder 127 while preventing various components of the turbomolecular pump 100 from overheating. This makes it possible to supply a sufficient amount of heat for vaporizing the deposits. Furthermore, since the high-temperature fluid is supplied while the turbomolecular pump 100 is stopped (exhaust) or operating at a low speed, it can be supplied after or between processes of a semiconductor device, etc.

By supplying the high-temperature fluid during low-speed (exhaust) operation of the turbomolecular pump 100, it is possible to prevent the high-temperature fluid from flowing back from the groove pump mechanism (Holbeck-type exhaust mechanism 204) to the turbomolecular pump mechanism. In addition, by supplying the high-temperature fluid while operating the auxiliary pump (back pump, not shown) connected to the exhaust port 133 (while drawing a vacuum with the auxiliary pump), it is also possible to prevent the high-temperature fluid from flowing back into the turbomolecular pump mechanism. Furthermore, by preventing the backflow of the high-temperature fluid, it is possible to prevent the turbomolecular pump mechanism from overheating.

In addition, by supplying high-temperature fluid while operating the auxiliary pump (back pump, not shown) connected to the exhaust port 133 (while drawing a vacuum with the auxiliary pump), the pressure inside the turbo molecular pump is reduced, making it possible to lower the sublimation temperature of the deposits. This allows the temperature of the high-temperature fluid to be lowered and the deposits to be vaporized.

In addition, the equipment for vaporizing the deposits (e.g., a fluid heating means such as a hot air generator 210, a flow control means such as a valve device 212, etc.) can be made part of the turbomolecular pump 100 (a vacuum pump component).

It is also possible that the equipment for vaporizing the deposits is not included in the turbomolecular pump 100. In this case, it is possible to configure a vacuum exhaust system by adding a fluid heating means for vaporizing the deposits (such as the hot air generator 210) and a flow control means (such as the valve device 212) to the turbomolecular pump 100. In Figures 1 and 5, the reference numeral 230 in parentheses indicates a vacuum exhaust system equipped with the turbomolecular pump 100, the hot air generator 210, and the valve device 212.

Second Embodiment
Next, a turbo molecular pump 310 according to a second embodiment will be described with reference to Fig. 6. Note that the same parts as those in the first embodiment are given the same names and reference numerals, and the description thereof will be omitted as appropriate.

In the turbomolecular pump 310 according to the second embodiment, the high-temperature fluid is supplied from the side close to the area where deposits tend to accumulate (the downstream side of the exhaust gas). In addition to the exhaust port 133, the turbomolecular pump 310 also has an outlet for the heating fluid (high-temperature fluid) (here, the heating fluid outlet 318, which will be described later).

In the turbomolecular pump 310 according to the second embodiment, a valve device 312 is connected to the exhaust port 15, and a hot air generator 210 is connected to the valve device 312. The valve device 312 is a three-way valve type, and is capable of switching the flow path. One port of the valve device 312 is connected to the hot air generator 210, and the other port is connected to a roughing pump (corresponding to the auxiliary pump (back pump) mentioned above, not shown).

The valve device 312 operates to allow gas to flow from the turbomolecular pump 310 to the roughing pump when roughing the vacuum system or exhausting process gases, etc. When vaporizing deposits (during cleaning), the valve device 312 operates to allow high-temperature fluid from the hot air generator 210 to flow into the turbomolecular pump 310. The operation of the valve device 312 may be controlled by the control device 200 (referring to FIG. 1), or may be controlled by a control device other than the control device 200 (valve control device, not shown).

The exhaust port 15 is used to discharge fluid when roughing the vacuum system or exhausting process gases, and is used to introduce fluid when vaporizing deposits. The space formed in front of the exhaust port 133 (upstream during exhaust) functions as a heating fluid outlet 218, as in the first embodiment, when roughing the vacuum system or exhausting process gases. However, when vaporizing deposits, the exhaust port 133 functions as a heating fluid introduction section (high-temperature fluid introduction section).

A heating fluid outlet port 316 is connected to the outer cylinder 127. The heating fluid outlet port 316 constitutes a heating fluid outlet 318. The heating fluid outlet port 316 is located at a position that is approximately 180 degrees out of phase with the exhaust port 133 (exhaust port 15).

The heating fluid outlet 318 formed by the heating fluid discharge port 316 is disposed in a position between the intake port 101 and the exhaust port 133 formed by the exhaust port 15 in the axial direction of the turbomolecular pump 310. The heating fluid outlet 318 is located upstream of the exhaust port 133 in the exhaust direction of the turbomolecular pump 310 (the direction from the upstream side to the downstream side of the exhaust gas). In other words, the exhaust port 133 is disposed downstream of the heating fluid outlet 318 in the path of the exhaust flow of the turbomolecular pump 310 .

A space that serves as the heating fluid outlet 320 is formed inside the outer cylinder 127. The heating fluid outlet 320 is located at the boundary between the turbomolecular pump mechanism and the thread groove pump mechanism (Holbeck type exhaust mechanism 204), similar to the heating fluid inlet 217 (FIG. 5) in the first embodiment. The heating fluid outlet 320 is spatially connected to the heating fluid outlet port 316.

The fluid transfer means 322 includes at least a portion of the hot air generator 210, the valve device 312, the exhaust port 15 (constituting the exhaust port 133), the portion in the outer cylinder 127 through which the high-temperature fluid flows, and the heating fluid outlet port 316 (constituting the heating fluid outlet 318). The fluid transfer means 322 is capable of supplying the fluid to the turbomolecular pump 310.

6 shows the flow path of the heating fluid by arrows A, C to E. In a situation where the valve device 312 spatially connects the hot air generator 210 and the inside of the turbo molecular pump 310 , the heating fluid passes through the hot air generator 210, the valve device 312, and the exhaust port 15 as shown by arrow A, and is introduced into the inside of the base part 129.

A part of the heating fluid (high-temperature fluid) introduced into the inside of the base part 129 flows in a ring shape (also called "cylindrical shape") in the circumferential direction of the base part 129 as shown by arrow C, and also flows to the opposite side (side separated by 180 degrees) of the base part 129. Although not shown in Fig. 6, the heating fluid (high-temperature fluid) also flows around to the rear side (also called "side not shown" or "side hidden in Fig. 6") of the side shown in Fig. 6. In addition, a part of the high-temperature fluid introduced into the base part 129 passes through the Holweck type exhaust mechanism part 204 and flows in the axial direction of the turbo molecular pump 310 inside the outer cylinder 127 as shown by arrow D.

The high-temperature fluid that has flowed inside the external cylinder 127 reaches the heating fluid outlet 318 as indicated by an arrow E, and is discharged to the outside of the external cylinder 127 through the heating fluid outlet 318. In the second embodiment, the high-temperature fluid is also introduced while the turbo molecular pump 310 is stopped (exhaust) or is operating at a low speed, as in the first embodiment.

According to the turbo molecular pump 310 of the second embodiment described above, the exhaust port 133 is utilized as a heating fluid inlet, and it is possible to flow the high-temperature fluid in the reverse direction toward the upstream side in the path of the exhaust flow of the turbo molecular pump 310. Then, the high-temperature fluid can be supplied from the vicinity of the portion where deposits are likely to occur (accumulate), and further, it is possible to distribute the high-temperature fluid throughout the Holweck type exhaust mechanism 204 and its surrounding areas before the temperature of the high-temperature fluid drops.

As described above in the first embodiment, deposits tend to accumulate in the Holweck-type exhaust mechanism 204 and its surrounding areas, particularly downstream of the exhaust gas (including the heating fluid outlet 218). With the turbomolecular pump 310 of the second embodiment, high-temperature fluid can be supplied from near the areas where deposits tend to accumulate, making it possible to heat the deposits more effectively.

In addition, the equipment for vaporizing the deposits (e.g., a fluid heating means such as the hot air generator 210, a flow control means such as the valve device 312, etc.) can be made part of the turbomolecular pump 310 (a vacuum pump component).

It is also possible that the device for vaporizing the deposits is not included in the turbomolecular pump 310. In this case, it is possible to configure a vacuum exhaust system in which a fluid heating means for vaporizing the deposits (such as the hot air generator 210) and a flow control means (such as the valve device 312) are added to the turbomolecular pump 310. In Fig. 6, the reference numeral 330 in parentheses indicates a vacuum exhaust system including the turbomolecular pump 310 , the hot air generator 210, the valve device 312, and the like.

Third Embodiment
Next, a turbomolecular pump 360 according to a third embodiment will be described with reference to Fig. 7 and Fig. 8. Note that the same parts as those in the other embodiments are given the same names and symbols, and the description thereof will be omitted as appropriate. In the turbomolecular pump 360 according to the third embodiment, the flow path for the heating fluid (high-temperature fluid) can be switched.

In the turbomolecular pump 360 according to the third embodiment, a heating fluid inlet port 362, which is a tubular flange part, is fixed to the base portion 129. The heating fluid inlet port 362 constitutes a fluid inlet port (heating fluid inlet port) 364 for the heating fluid.

The heating fluid introduction port 362 protrudes radially from the base portion 129. The tip of the heating fluid introduction port 362 is connected to the valve device 212, which is connected to the hot air generator 210. The heating fluid introduction port 362 can be the same as the heating fluid introduction port 214 in the first embodiment.

A space that serves as the heating fluid introduction section 366 is formed inside the base section 129. The heating fluid introduction section 366 is spatially connected to the heating fluid inlet 364 of the heating fluid introduction port 362. The heating fluid introduction port 362 is located at a position that is approximately 180 degrees out of phase with the exhaust port 133 (exhaust port 15).

A heating fluid inlet 364 formed by the heating fluid introduction port 362 is disposed in the same position as the exhaust port 133 formed by the exhaust port 15 in the axial direction of the turbo molecular pump 360 .

A heating fluid outlet port 368 is connected to the outer cylinder 127. The heating fluid outlet port 368 is located almost directly above the exhaust port 133 (exhaust port 15). The heating fluid outlet port 368 constitutes a heating fluid outlet 370.

The heating fluid outlet 370 formed by the heating fluid discharge port 368 is disposed in a position between the intake port 101 and the exhaust port 133 formed by the exhaust port 15 in the axial direction of the turbo molecular pump 360. The heating fluid outlet 370 is located upstream of the exhaust port 133 in the exhaust direction of the turbo molecular pump 360 (the direction from the upstream side to the downstream side of the exhaust gas). In other words, the heating fluid outlet 370 is disposed upstream of the exhaust port 133 in the path of the exhaust flow of the turbo molecular pump 360 .

A space that serves as the heating fluid outlet 372 is formed inside the outer cylinder 127. The heating fluid outlet 372 is located at the boundary between the turbomolecular pump mechanism and the thread groove pump mechanism (Holbeck type exhaust mechanism 204), similar to the heating fluid inlet 217 (FIG. 5) in the first embodiment. The heating fluid outlet 372 is spatially connected to the heating fluid outlet 370 of the heating fluid outlet port 368.

In the third embodiment, as shown in FIG. 7, the first fluid transfer means 374 is configured to include at least a portion of the hot air generator 210, the valve device 212, the heating fluid inlet port 362 (constituting the heating fluid inlet 364), the portion in the outer cylinder 127 through which the high-temperature fluid flows, and the exhaust port 15 (constituting the exhaust port 133).

In the third embodiment, as shown in FIG. 8, the second fluid transfer means 376 is configured to include at least a portion of the hot air generator 210, the valve device 212, the heating fluid inlet port 362 (constituting the heating fluid inlet 364), the portion in the outer cylinder 127 through which the high-temperature fluid flows, and the heating fluid outlet port 368 (constituting the heating fluid outlet 370).

In the first fluid transfer means 374 shown in FIG. 7, a flow of high-temperature fluid is formed from the heating fluid inlet 364 toward the exhaust port 133, as shown by arrows A to E (flow path A). In the first fluid transfer means 374, the above-mentioned "part in the outer cylinder 127 where the high-temperature fluid flows" is mainly the part closer to the exhaust port 133, as shown by arrow C.

As described above in the second embodiment, deposits tend to accumulate in the Holweck-type exhaust mechanism 204 and its surrounding areas, particularly downstream of the exhaust gas. For this reason, by supplying high-temperature fluid via the first fluid transfer means 374, it is possible to supply high-temperature fluid intensively to areas where deposits tend to accumulate.

8, in the second fluid transfer means 376, a flow of high-temperature fluid is formed from the heating fluid inlet 364 toward the heating fluid outlet 370, as shown by arrows A to E (flow path B). In the second fluid transfer means 376, the above-mentioned "part through which the high-temperature fluid flows inside the outer cylinder 127" is the part that mainly ranges from the part close to the exhaust port 133 to the boundary between the turbo molecular pump mechanism and the thread groove pump mechanism (Holbeck type exhaust mechanism 204), as shown by arrows C and D.

By supplying high-temperature fluid via the second fluid transfer means 376, high-temperature fluid can be supplied to the entire area where deposits tend to accumulate.

The supply of high-temperature fluid by the first fluid transfer means 374 (FIG. 7) and the supply of high-temperature fluid by the second fluid transfer means 376 (FIG. 8) can be performed, for example, by connecting a three-way valve type valve device (not shown) and one roughing pump (auxiliary pump (back pump), not shown) between the exhaust port 15 and the heating fluid outlet port 368, and controlling the switching of flow paths A/B by the valve device (not shown). The control of this valve device (not shown) may be performed by the control device 200 (referring to FIG. 1), or by providing a control device other than the control device 200 (valve control device, not shown).

In addition, an ON/OFF type valve device (not shown) and a roughing pump (auxiliary pump (back pump), not shown) may be connected to each of the exhaust port 15 and the heating fluid outlet port 368. In this case, when high-temperature fluid is supplied by the first fluid transfer means 374 (Figure 7), the roughing pump connected to the exhaust port 15 operates. In addition, when high-temperature fluid is supplied by the second fluid transfer means 376 (Figure 8), the roughing pump connected to the heating fluid outlet port 368 operates.

In the third embodiment, the high-temperature fluid is introduced while the turbo molecular pump 360 is stopped (exhaust) or is operating at a low speed, as in the first and second embodiments. When the purpose is to clean the Holweck type exhaust mechanism 204 and its surrounding areas, particularly areas where deposits are likely to accumulate, the high-temperature fluid is supplied to flow path A by the first fluid transfer means 374, as shown in Fig. 7. When the purpose is to clean the Holweck type exhaust mechanism 204 and its surrounding areas overall, the high-temperature fluid is supplied to flow path B by the second fluid transfer means 376, as shown in Fig. 8.

According to the turbo molecular pump 360 of the third embodiment described above, cleaning according to the purpose can be performed by switching between flow paths A/B (FIG. 7/FIG. 8). Furthermore, by cleaning flow paths A/B continuously (or at relatively short intervals), highly effective cleaning can be performed.

In addition, the equipment for vaporizing the deposits (e.g., a fluid heating means such as the hot air generator 210, a flow control means such as the valve device 212, etc.) can be made part of the turbomolecular pump 360 (a vacuum pump component).

It is also possible that the equipment for vaporizing the deposits (e.g., fluid heating means such as the hot air generator 210, flow control means such as the valve device 212, etc.) is not included in the turbomolecular pump 360. In this case, a vacuum exhaust system can be configured by adding fluid heating means for vaporizing the deposits (such as the hot air generator 210) and flow control means heat (such as the valve device 212) to the turbomolecular pump 360. In Figures 7 and 8, the reference numeral 380 in parentheses indicates a vacuum exhaust system equipped with the turbomolecular pump 310, the hot air generator 210, and the valve device 212, etc.

Fourth Embodiment
Next, a vacuum exhaust system 410 according to a fourth embodiment will be described with reference to Fig. 10. Note that the same parts as those in the other embodiments are given the same names and reference numerals, and the description thereof will be omitted as appropriate.

In each of the embodiments (first to third embodiments) described so far, the supply of the heating purge gas is performed by sequentially feeding new heating purge gas into the turbomolecular pumps 100, 310, and 360. For example, FIG. 9 shows a schematic diagram of a method of supplying the heating purge gas for the turbomolecular pump 100 (FIGS. 1 and 5) of the first embodiment. As shown in FIG. 9, the vacuum exhaust system 230 includes the turbomolecular pump 100, the hot air generator 210, the inlet valve device 212, and the outlet valve device 390. Here, unlike FIG. 9, the outlet valve device 390 is not shown in FIGS. 1 and 5.

As explained in the first embodiment, the heating purge gas that has passed through the hot air generator 210 becomes hot air (high-temperature fluid) and flows out of the hot air generator 210 as shown by arrow A and toward the inlet valve device 212. The high-temperature fluid that has passed through the inlet valve device 212 is supplied to the inside of the turbomolecular pump 100 as shown by arrow B.

The high-temperature fluid heats the inside of the turbomolecular pump 100, vaporizes the deposits, and flows out of the turbomolecular pump 100 as shown by arrow E. In the vacuum exhaust system 230 of the first embodiment shown in FIG. 9, the high-temperature fluid flowing out of the turbomolecular pump 100 is discharged through the outlet valve device 390. The outlet valve device 390 is connected to the roughing pump (the auxiliary pump (back pump) mentioned above). In this way, the used heating purge gas that heated the inside of the turbomolecular pump 100 is discharged without being reused.

In contrast, FIG. 10 shows a schematic diagram of a vacuum exhaust system 410 according to a fourth embodiment. The vacuum exhaust system 410 according to the fourth embodiment recovers the high-temperature fluid used, separates the vaporized deposits from the gas (here, N2 gas) used in the high-temperature fluid, and reuses the separated gas.

The vacuum exhaust system 410 includes a turbo molecular pump 100, a hot air generator 210, a first valve device 212, a second valve device 312, a cooling trap (hereinafter referred to as a "trap") 412, and a circulation pump 414. The first valve device 212 is an ON/OFF type, and the second valve device 312 is a three-way valve type. The second valve device 312 is connected to a roughing pump (the auxiliary pump (back pump) described above). In the vacuum exhaust system 410, these devices form a fluid circulation path 416 that connects a fluid outlet (here, the exhaust port 133 referring to FIG. 1) and a fluid inlet (here, the heating fluid inlet 216 referring to FIG. 1).

Trap 412 is formed in a container shape and has many fins (not shown) inside. The many fins (not shown) ensure that trap 412 has a large cooling area. Trap 412 is equipped with, for example, a cooling water pipe (not shown) for circulating cooling water, and the internal fins are cooled by the cooling water.

The gas discharged from the turbomolecular pump 100 (high-temperature fluid containing vaporized components of the deposits) flows into the trap 412, comes into contact with fins (not shown) and is cooled, and then is returned to the hot air generator 210. The trap 412 cools the gas discharged from the turbomolecular pump 100. When the gas that flows into the trap 412 is cooled below the sublimation temperature of the vaporized (gasified) deposits, the vaporized components of the deposits solidify and adhere to the fins (not shown) inside the trap 412. As a result, the deposits and N2 gas are separated in the turbomolecular pump 100, and the N2 gas is discharged from the trap 412.

A filter 418 is installed at the outlet of the trap 412, and solids that do not adhere to the fins (not shown) are captured by the filter 418. This prevents powdery deposits from being discharged from the trap 412. It also prevents the powder discharged from the trap 412 from becoming caught in the circulation pump 414. The filter 418 may be installed inside the trap 412.

In the vacuum exhaust system 410 according to the fourth embodiment described above, a fluid circulation path 416 is formed that connects a fluid outlet (here, exhaust port 133 referring to FIG. 1) and a fluid inlet (here, heating fluid inlet 216 referring to FIG. 1), and a trap 412 is provided in the circulation path 416. With this vacuum exhaust system 410, it is possible to reuse the heating fluid (and high-temperature fluid) without disposing of it. It is also possible to reduce the consumption of the heating fluid. As a result, it is possible to reduce both the parts cost for cleaning the inside of the turbomolecular pump 100 and the operating cost for cleaning.

The gas reuse configuration of the vacuum exhaust system 410 according to the fourth embodiment can also be applied to the turbomolecular pumps 100, 310, and 360 and the vacuum exhaust systems 230, 330, and 380 according to the first to third embodiments, unless there are particular problems.

Fifth Embodiment
Next, a vacuum exhaust system 430 according to a fifth embodiment will be described with reference to Fig. 11. Note that parts similar to those in the other embodiments are given the same names and symbols, and descriptions thereof will be omitted as appropriate. Fig. 11 shows a schematic diagram of a turbomolecular pump 420 according to the fifth embodiment. In each of the embodiments described so far, the hot air generator 210 is disposed outside the turbomolecular pump 100, 310, 360. However, in the vacuum exhaust system 430 according to the fifth embodiment, a heater unit 422 is disposed inside the turbomolecular pump 420.

The heater section 422 may be the same as the heater section (not shown) built into the hot air generator 210 in the first embodiment. The heater section 422 is installed in the heating fluid introduction section 217 similar to that in the first embodiment. The heater section 422 may be controlled by the control device 200 (refer to FIG. 1), or may be controlled by a control device (heater section control device, not shown) other than the control device 200.

In the vacuum exhaust system 430 according to the fifth embodiment, a fan device 424 is connected to the outside of the turbomolecular pump 420 instead of the hot air generator 210 of the first embodiment. The fan device 424 supplies a heating fluid to the turbomolecular pump 420, and the supplied heating fluid is introduced into the heating fluid introduction section 217 inside the outer cylinder 127, where it is heated as it passes through the heater section 422, becoming a high-temperature fluid.

In addition, it is possible for the equipment for vaporizing the deposits (e.g., fluid heating means such as the fan device 424, the heater section 422, flow control means such as the valve device 212, etc.) to be part of the turbomolecular pump 420 (vacuum pump components). Also, it is possible for the heater section 422 to be a vacuum pump component, and for the fan device 424 to be something that is not included in the vacuum pump components.

Furthermore, the fan device 424 and the heater section 422 are not included in the vacuum pump components, and can be components that, together with the turbomolecular pump 420, make up the vacuum exhaust system 430.

<Modification>
In the first embodiment (FIG. 5), the heating fluid inlet 216 formed by the heating fluid introduction port 214 is provided at only one location in the exhaust path of the exhaust gas (path from the intake port 101 to the exhaust port 133). In the third embodiment (FIG. 7), the heating fluid inlet 364 formed by the heating fluid introduction port 362 is also provided at only one location in the exhaust path of the exhaust gas. However, the present invention is not limited to this, and for example, a plurality of heating fluid introduction ports 214 (and heating fluid inlet 216) and heating fluid introduction ports 362 (and heating fluid inlet 364) may be provided in the exhaust path of the exhaust gas.

In addition, the heating fluid introduction port 214 (and the heating fluid inlet 216) may not be provided on the outer cylinder 127, but may be provided, for example, on the vacuum chamber of the target device evacuated by the turbomolecular pump 100, 310, 360, 420, or on the piping connecting the vacuum chamber and the turbomolecular pump 100, 310, 360, 420, and may be allowed to flow in through the intake port 101.

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.

15: exhaust port 100, 310, 360, 420: turbo molecular pump 101: intake port 102: rotor 103: rotor 113: rotor shaft 121: motor 123: fixed blade 127: outer cylinder 129: base 133: exhaust port 204: Holweck type exhaust mechanism 210: hot air generator 212, 312: valve device 214, 362: heating fluid introduction port 216, 364: heating fluid inlet 217, 366: heating fluid introduction section 218, 320, 372: heating fluid outlet 220: fluid transfer means 230, 330, 380, 410 , 430: vacuum exhaust system 316, 368: heating fluid outlet port 318, 370: heating fluid outlet 322 : Fluid transfer means 374 : First fluid transfer means 376 : Second fluid transfer means 412 : Trap 414 : Circulation pump 416 : Circulation path 418 : Filter 422 : Heater section 424 : Fan device

Claims (9)

a fluid heating means for heating the fluid to a temperature above the sublimation temperature of the deposit ;
A fluid inlet that is an inlet for the fluid;
and a flow control means for controlling the flow of the fluid,
The flow control means
A vacuum pump characterized in that a flow of the fluid is controlled so that the fluid is supplied into the vacuum pump while the vacuum pump is stopped or operating at a low speed, the flow exceeding a maximum flow rate that can be exhausted during rated operation . a fluid transfer means capable of supplying the fluid to the vacuum pump;
2. The vacuum pump of claim 1, capable of delivering at least 10 times the maximum flow rate of said fluid to said vacuum pump. 3. The vacuum pump according to claim 1, further comprising a fluid outlet which is an outlet for the fluid. 4. The vacuum pump according to claim 3, wherein the fluid inlet is disposed downstream of the fluid outlet in a path of exhaust flow of the vacuum pump. A circulation path for the fluid is formed, the circulation path connecting the fluid outlet and the fluid inlet,
4. The vacuum pump according to claim 3, further comprising a trap provided in the circulation path. A circulation path for the fluid is formed, the circulation path connecting the fluid outlet and the fluid inlet,
5. The vacuum pump according to claim 4, further comprising a trap provided in the circulation path. a fluid heating means for heating the fluid to a temperature above the sublimation temperature of the deposit ;
a vacuum pump having a fluid inlet for the fluid;
and a flow control means for controlling the flow of the fluid,
The flow control means
A vacuum pumping system characterized in that a flow of the fluid is controlled so that the fluid is supplied into the vacuum pump while the vacuum pump is stopped or operating at a low speed, the flow exceeding a maximum flow rate that can be pumped during rated operation. 8. The vacuum exhaust system according to claim 7, further comprising a fluid outlet which is an outlet for the fluid. A circulation path for the fluid is formed, the circulation path connecting the fluid outlet and the fluid inlet,
9. The vacuum pumping system according to claim 8, further comprising a trap provided in the circulation path.