WO2023157586A1

WO2023157586A1 - Cryopump and method for driving cryopump

Info

Publication number: WO2023157586A1
Application number: PCT/JP2023/002219
Authority: WO
Inventors: 嵩裕中西
Original assignee: 住友重機械工業株式会社
Priority date: 2022-02-18
Filing date: 2023-01-25
Publication date: 2023-08-24
Also published as: TW202334551A; JP2023120890A

Abstract

A cryopump (10) is attachable to a vacuum chamber through a gate valve (102). The cryopump (10) is provided with a refrigerator (14), and a controller (60) that is configured to detect whether or not the gate valve (102) is closed, and to control the refrigerator (14) to increase the refrigeration capacity of the refrigerator (14) when the gate valve (102) is closed, in comparison to when the gate valve (102) is opened.

Description

Cryopumps and operating methods of cryopumps

The present invention relates to a cryopump and a cryopump operating method.

A cryopump is a vacuum pump that traps gas molecules by condensation or adsorption in a cryopanel cooled to an extremely low temperature and exhausts it. Cryopumps are generally used to realize a clean vacuum environment required for semiconductor circuit manufacturing processes and the like.

JP 2012-237293 A

In order to sufficiently increase the degree of vacuum in the vacuum chamber in preparation for starting the vacuum process in the vacuum chamber of the vacuum process equipment, the vacuum chamber is first roughed and then switched to evacuation by the cryopump. During roughing of the vacuum chamber, a gate valve provided between the vacuum chamber and the cryopump is closed and opened to initiate evacuation by the cryopump. At this time, the ultimate pressure inside the cryopump is already considerably lower than the roughing pressure of the vacuum chamber. Therefore, a large amount of gas temporarily flows into the cryopump from the vacuum chamber, which may result in a heat load on the refrigerator that cools the cryopump, causing an overshoot in the cryopanel temperature. Such temperature rise is also called crossover. An increase in temperature of the cryopanel may have an undesirable effect on the pumping performance of the cryopump in some cases.

In addition, the permissible range of cryopanel temperature is sometimes determined in advance as a unique setting in the vacuum process equipment. When it is detected that the allowable temperature range has been exceeded as a result of the overshoot described above, the vacuum process apparatus can take actions to ensure safety, such as issuing an alert or emergency closing of the gate valve. The vacuum process equipment has to wait until the cryopanel temperature returns to within the allowable range, which delays the start of the vacuum process.

An exemplary object of an aspect of the present invention is to provide a cryopump that can mitigate overshoot of the cryopanel temperature that can occur during crossover.

According to one aspect of the present invention, a cryopump is provided that can be attached to a vacuum chamber via a gate valve. The cryopump detects whether the refrigerator and the gate valve are closed, and controls the refrigerator so that the refrigerating capacity of the refrigerator when the gate valve is closed is increased compared to when the gate valve is open. a controller configured to control the

According to one aspect of the present invention, a cryopump operating method is provided. The cryopump can be attached to the vacuum chamber via a gate valve and has a refrigerator. The method includes detecting whether the gate valve is closed and increasing the refrigerating capacity of the refrigerator when the gate valve is closed compared to when the gate valve is open.

According to one aspect of the invention, a cryopump senses whether regeneration of the refrigerator and cryopump has been completed, and provides a refrigeration cycle to temporarily increase the refrigerating capacity of the refrigerator following completion of regeneration. a controller for controlling the machine.

According to one aspect of the present invention, a cryopump operating method is provided. A cryopump includes a refrigerator. The method includes detecting whether regeneration of the cryopump is complete, and temporarily increasing refrigeration capacity of the refrigerator following regeneration completion.

It should be noted that arbitrary combinations of the above-described constituent elements and those in which the constituent elements and expressions of the present invention are replaced with each other between methods, devices, systems, etc. are also effective as embodiments of the present invention.

According to the present invention, it is possible to provide a cryopump capable of alleviating overshoot of the cryopanel temperature that may occur during crossover.

1 is a diagram schematically showing a cryopump according to an embodiment; FIG. 1 is a block diagram schematically showing the configuration of a control device for a cryopump according to an embodiment; FIG. 4 is a flow chart showing an example of a method of operating a cryopump according to an embodiment; FIG. 4A is a diagram showing the operation of the cryopump according to the comparative example, and FIG. 4B is a diagram showing the operation of the cryopump according to the embodiment. 8 is a flow chart showing another example of a method of operating a cryopump according to an embodiment; FIG. 11 is a block diagram schematically showing the configuration of a cryopump control device according to another embodiment;

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description and drawings, the same or equivalent constituent elements, members, and processes are denoted by the same reference numerals, and overlapping descriptions are omitted as appropriate. The scales and shapes of the illustrated parts are set for convenience in order to facilitate explanation, and should not be construed as limiting unless otherwise specified. The embodiment is an example and does not limit the scope of the present invention. All features and combinations thereof described in the embodiments are not necessarily essential to the invention.

FIG. 1 is a diagram schematically showing a cryopump 10 according to an embodiment. FIG. 2 is a block diagram schematically showing the configuration of the control device for the cryopump 10 according to the embodiment.

The cryopump 10 can be attached via a gate valve 102 to a vacuum chamber 100 of, for example, an ion implanter, sputtering device, vapor deposition device, or other vacuum process device. A vacuum chamber 100 and a portion of the gate valve 102 are shown in FIG. 1 along with the cryopump 10 .

The cryopump 10 is attached to the vacuum chamber 100 via the gate valve 102 and used to raise the degree of vacuum inside the vacuum chamber 100 to the level required for the desired vacuum process. The cryopump 10 has a cryopump inlet (hereinafter also simply referred to as “inlet”) 12 for receiving gas to be evacuated from the vacuum chamber 100 . Gas enters the internal space of the cryopump 10 from the vacuum chamber 100 through the gate valve 102 and the intake port 12 .

In the following, the terms "axial direction" and "radial direction" may be used in order to express the positional relationship of the constituent elements of the cryopump 10 in an easy-to-understand manner. The axial direction of the cryopump 10 represents the direction passing through the intake port 12 (that is, the direction along the central axis of the cryopump 10, which is the vertical direction in the drawing), and the radial direction represents the direction along the intake port 12 (the center of the cryopump 10). It is the direction perpendicular to the axis, and represents the left-right direction in the figure. For the sake of convenience, the position relatively close to the air inlet 12 in the axial direction may be referred to as "upper", and the position relatively farther away may be referred to as "lower". In other words, relatively far from the bottom of the cryopump 10 may be called "upper", and relatively close to it may be called "lower". With respect to the radial direction, the area near the center of the intake port 12 may be called "inside", and the area near the periphery of the intake port 12 may be called "outside". Note that such expressions are not related to the arrangement of the cryopump 10 when attached to the vacuum chamber 100 . For example, the cryopump 10 may be mounted vertically in the vacuum chamber 100 with the inlet 12 facing downward.

Also, the direction surrounding the axial direction is sometimes called the "circumferential direction". The circumferential direction is a second direction along the intake port 12 and is a tangential direction perpendicular to the radial direction.

The cryopump 10 includes a refrigerator 14 , a cryopump container 16 , a first-stage cryopanel 18 , and a cryopanel unit 20 . The first stage cryopanel 18 may also be referred to as a high temperature cryopanel section or a 100K section. The cryopanel unit 20 is a second-stage cryopanel and can also be called a low-temperature cryopanel section, a 10K section, or the like.

The refrigerator 14 is, for example, a cryogenic refrigerator such as a Gifford-McMahon refrigerator (so-called GM refrigerator). The refrigerator 14 is a two-stage refrigerator and includes a first cooling stage 22 and a second cooling stage 24 . The refrigerator 14 is configured to cool the first cooling stage 22 to a first cooling temperature and the second cooling stage 24 to a second cooling temperature. The second cooling temperature is lower than the first cooling temperature. For example, the first cooling stage 22 is cooled to about 60K to 120K, preferably 80K to 100K, and the second cooling stage 24 is cooled to about 10K to 20K. First cooling stage 22 and second cooling stage 24 may be referred to as a hot cooling stage and a cold cooling stage, respectively.

The refrigerator 14 also includes a refrigerator structural portion 21 that structurally supports the second cooling stage 24 on the first cooling stage 22 and structurally supports the first cooling stage 22 on the room temperature portion 26 of the refrigerator 14 . Prepare. Therefore, the refrigerator structure 21 includes a first cylinder 23 and a second cylinder 25 coaxially extending along the radial direction. A first cylinder 23 connects a room temperature section 26 of the refrigerator 14 to the first cooling stage 22 . A second cylinder 25 connects the first cooling stage 22 to the second cooling stage 24 . Typically, the first cooling stage 22 and the second cooling stage 24 are made of a highly thermally conductive metallic material such as copper (eg, pure copper), and the first cylinder 23 and the second cylinder 25 are made of other metallic material, such as stainless steel. It is formed. The room temperature section 26, the first cylinder 23, the first cooling stage 22, the second cylinder 25, and the second cooling stage 24 are arranged linearly in this order.

A first displacer and a second displacer (not shown) are reciprocally arranged inside the first cylinder 23 and the second cylinder 25, respectively. A first regenerator and a second regenerator (not shown) are incorporated in the first displacer and the second displacer, respectively. The room temperature section 26 also has a drive mechanism (not shown) for reciprocating the first displacer and the second displacer. The drive mechanism includes a refrigerator motor 50, which will be described later. The driving mechanism also includes a channel switching mechanism that switches the channel of the working gas so as to periodically repeat the supply and discharge of the working gas (for example, helium) to the inside of the refrigerator 14 .

The refrigerator 14 is connected to a working gas compressor (not shown). The refrigerator 14 expands the working gas pressurized by the compressor to cool the first cooling stage 22 and the second cooling stage 24 . The expanded working gas is recovered by the compressor and pressurized again. The refrigerator 14 generates cold by repeating thermal cycles including supply and discharge of the working gas and synchronized reciprocating motion of the first displacer and the second displacer.

The illustrated cryopump 10 is a so-called horizontal cryopump. A horizontal cryopump is generally a cryopump in which the refrigerator 14 is arranged to intersect (normally perpendicular to) the central axis of the cryopump 10 . The present invention can also be applied to so-called vertical cryopumps. A vertical cryopump is a cryopump in which a refrigerator is arranged along the axial direction of the cryopump.

The cryopump container 16 is a housing of the cryopump 10 that houses the refrigerator 14, the first-stage cryopanel 18, and the cryopanel unit 20, and is configured to keep the internal space of the cryopump 10 airtight. there is The cryopump container 16 has an inlet flange 16a extending radially outward from its front end over the entire circumference. The inlet flange 16a defines the inlet 12 radially inwardly thereof. The cryopump container 16 includes a container body portion 16b extending in the axial direction from the inlet flange 16a, a container bottom portion 16c that closes the container body portion 16b on the side opposite to the inlet port 12, the inlet flange 16a and the container bottom portion 16c. and a refrigerator housing cylinder 16d extending laterally between the .

An end portion of the refrigerator housing tube 16d is attached to the room temperature portion 26 of the refrigerator 14 on the side opposite to the container body portion 16b, whereby the low temperature portion of the refrigerator 14 (that is, the first cylinder 23, the first cooling stage 22 , a second cylinder 25 , and a second cooling stage 24 ) are disposed within the cryopump vessel 16 without contact with the cryopump vessel 16 . The first cylinder 23 is arranged inside the refrigerator housing tube 16d, and the first cooling stage 22, the second cylinder 25, and the second cooling stage 24 are arranged inside the container body 16b. The first stage cryopanel 18 and the cryopanel unit 20 are also arranged in the container body 16b.

The first stage cryopanel 18 includes a radiation shield 30 and an entrance cryopanel 32 and surrounds the cryopanel unit 20 . The first stage cryopanel 18 provides a cryogenic surface to protect the cryopanel unit 20 from radiant heat from outside the cryopump 10 or from the cryopump vessel 16 . The first stage cryopanel 18 is thermally coupled to the first cooling stage 22 and cooled to a first cooling temperature. The first stage cryopanel 18 has a gap with the cryopanel unit 20 , and the first stage cryopanel 18 is not in contact with the cryopanel unit 20 . The first stage cryopanel 18 is also not in contact with the cryopump vessel 16 .

The radiation shield 30 is provided to protect the cryopanel unit 20 from radiant heat from the cryopump container 16 . The radiation shield 30 axially extends from the inlet 12 toward the container bottom 16 c within the cryopump container 16 in a cylindrical shape (for example, a cylindrical shape). The radiation shield 30 is open on the inlet port 12 side and closed on the container bottom 16c side. A radiation shield 30 is between the cryopump vessel 16 and the cryopanel unit 20 and surrounds the cryopanel unit 20 . The radiation shield 30 has a slightly smaller diameter than the cryopump vessel 16 to form a shield outer gap 31 between the radiation shield 30 and the cryopump vessel 16 . Therefore, the radiation shield 30 is not in contact with the cryopump vessel 16 .

The first cooling stage 22 of the refrigerator 14 is directly attached to the side outer surface of the radiation shield 30 . Thus, the radiation shield 30 is thermally coupled to the first cooling stage 22 and thus cooled to the first cooling temperature. The radiation shield 30 may be attached to the first cooling stage 22 via an appropriate heat transfer member. Also, the second cooling stage 24 and the second cylinder 25 of the refrigerator 14 are inserted into the radiation shield 30 from the side of the radiation shield 30 .

The inlet cryopanel 32 is provided at the inlet 12 to protect the cryopanel unit 20 from radiant heat from a heat source outside the cryopump 10 (for example, a heat source inside the vacuum chamber to which the cryopump 10 is attached). . The inlet cryopanel 32 is thermally coupled to the first cooling stage 22 through the radiation shield 30 and, like the radiation shield 30, is cooled to the first cooling temperature. Thus, gas (eg, moisture) that condenses at the first cooling temperature is trapped on the surface.

The cryopanel unit 20 includes a plurality of cryopanels each thermally coupled to the second cooling stage 24 and cooled to a second cooling temperature lower than the first cooling temperature. These cryopanels may be arranged axially from the inlet 12 toward the vessel bottom 16c as shown. At least part of the surface of the cryopanel may be provided with an adsorbent (eg, activated carbon) to capture non-condensable gas (eg, hydrogen) by adsorption. The cryopanel unit 20 is arranged below the entrance cryopanel 32 so as to be surrounded by the radiation shield 30 inside the cryopump container 16 . The cryopanel unit 20 is not in contact with the radiation shield 30 and the entrance cryopanel 32 . Various known configurations can be appropriately adopted for the configuration of the cryopanel unit 20, such as the arrangement and shape of the cryopanels, and thus the details thereof will not be described here.

A gate valve 102 is installed between the cryopump 10 and the vacuum chamber 100 . Gate valve 102 includes a valve housing 104 and a valve plate 106 . The valve housing 104 forms a communication path connecting the opening of the vacuum chamber 100 to the inlet 12 of the cryopump 10 . The valve housing 104 has flanges on both sides of this communicating passage, one of which is attached to the flange of the vacuum chamber 100 surrounding the opening of the vacuum chamber 100, and the other of which is the inlet flange 16a. can be attached to

The gate valve 102 is closed as necessary, such as when performing maintenance on the vacuum chamber 100 or the cryopump 10. The flange portion of the valve housing 104 on the inlet flange 16a side also serves as the valve seat portion of the gate valve 102, and the gate valve 102 is closed by the valve plate 106 as a valve element coming into close contact with this valve seat portion. At this time, gas flow from the vacuum chamber 100 to the cryopump 10 through the inlet 12 is cut off. The cryopump 10 is isolated from the vacuum chamber 100, and the internal space of the cryopump 10 is kept airtight.

The gate valve 102 is opened to evacuate the vacuum chamber 100 by the cryopump 10 . A valve plate housing portion 108 is provided in the valve housing 104. As shown by the dashed line in FIG. Valve 102 opens. Gas can enter the internal space of the cryopump 10 from the vacuum chamber 100 through the gate valve 102 and the inlet 12 . Thus, the vacuum chamber 100 can be evacuated by the cryopump 10 in order to perform a desired vacuum process within the vacuum chamber 100 .

As shown in FIG. 2, the cryopump 10 includes a first temperature sensor 40 for measuring the temperature of the first cooling stage 22 and a second temperature sensor 42 for measuring the temperature of the second cooling stage 24. , may be provided. The first temperature sensor 40 is attached to the first cooling stage 22 or the first stage cryopanel 18 , and the second temperature sensor 42 is attached to the second cooling stage 24 or the cryopanel unit 20 . Therefore, the first temperature sensor 40 can measure the temperature of the first stage cryopanel 18 and output a first measured temperature signal T1 indicating the measured temperature of the first stage cryopanel 18 . The second temperature sensor 42 can measure the temperature of the cryopanel unit 20 and output a second measured temperature signal T2 indicative of the measured temperature of the cryopanel unit 20 .

The refrigerator 14 includes a refrigerator motor 50 that drives the refrigerator 14 and a refrigerator inverter 52 that controls the operating frequency of the refrigerator 14 . The operating frequency (also referred to as operating speed) of the refrigerator 14 represents the operating frequency or rotation speed of the refrigerator motor 50, the operating frequency of the refrigerator inverter 52, the heat cycle frequency, or any of these. The heat cycle frequency is the number of heat cycles performed in the refrigerator 14 per unit time.

The cryopump 10 also includes a controller 60 that controls the cryopump 10 . The controller 60 may be provided integrally with the cryopump 10 or may be configured as a control device separate from the cryopump 10 .

The controller 60 is connected to the first temperature sensor 40 to receive the first measured temperature signal T1 from the first temperature sensor 40, and is connected to the second temperature sensor 42 to receive the second measured temperature signal T2 from the second temperature sensor 42. It may be connected to the sensor 42 . The refrigerator inverter 52 described above may be provided in the controller 60 .

The controller 60 may be configured to control the refrigerator 14 based on the cooling temperature of the first stage cryopanel 18 or based on the cooling temperature of the cryopanel unit 20 during the evacuation operation of the cryopump 10 . good. For example, the controller 60 may control the operating frequency of the refrigerator 14 through feedback control so as to minimize the deviation between the target temperature of the first cooling stage 22 and the temperature measured by the first temperature sensor 40 .

The target temperature of the first cooling stage 22 is normally set to a constant value. The target temperature of the first cooling stage 22 is specified, for example, according to the process performed in the vacuum chamber 100 to which the cryopump 10 is attached. The target temperature may be changed as needed during operation of the cryopump 10 .

The controller 60 may determine the operating frequency F of the refrigerator motor 50 as a function of the deviation between the measured temperature and the target temperature (for example, by PID control). The operating frequency F of the refrigerator motor 50 is determined within a predetermined operating frequency range. The operating frequency range is defined by predetermined upper and lower operating frequency limits. The controller 60 outputs the determined operating frequency F to the refrigerator inverter 52 .

The refrigerator inverter 52 is configured to provide variable frequency control of the refrigerator motor 50 . The refrigerator inverter 52 converts the input power to have the operating frequency F input from the controller 60 . Input power to the refrigerator inverter 52 is supplied from a refrigerator power supply (not shown). The refrigerator power supply may be a commercial power supply. Refrigerator inverter 52 outputs the converted electric power to refrigerator motor 50 . Thus, the refrigerator motor 50 is driven at the operating frequency F determined by the controller 60 and output from the refrigerator inverter 52 .

The temperature of the first cooling stage 22 can rise when the heat load on the cryopump 10 increases. When the temperature measured by the first temperature sensor 40 is higher than the target temperature, the controller 60 increases the operating frequency of the refrigerator 14 . As a result, the frequency of the heat cycle in the refrigerator 14 is also increased, and the first stage cryopanel 18 and the first cooling stage 22 are cooled toward the target temperature. Conversely, when the temperature measured by the first temperature sensor 40 is lower than the target temperature, the operating frequency of the refrigerator 14 is decreased and the temperature of the first cooling stage 22 is raised toward the target temperature. Thus, the temperature of the first stage cryopanel 18 can be kept within a temperature range near the target temperature. Such control helps reduce the power consumption of the cryopump 10 because the operating frequency of the refrigerator 14 can be appropriately adjusted according to the heat load.

Controlling the temperature of the first cooling stage 22 in accordance with the target temperature of the refrigerator 14 is hereinafter sometimes referred to as "one-stage temperature control". In one-stage temperature control, the two-stage cooling temperature is not directly controlled. That is, as a result of the one-stage temperature control, the second cooling stage 24 and the cryopanel unit 20 are cooled to a temperature determined by the two-stage cooling capacity of the refrigerator 14 and the heat load from the outside to the second cooling stage 24. be done.

Similarly, the controller 60 can control the temperature of the second cooling stage 24 according to the target temperature of the refrigerator 14, so to speak, "two-stage temperature control". In this case, the controller 60 may control the operating frequency of the refrigerator 14 by feedback control so as to minimize the deviation between the target temperature of the second cooling stage 24 and the temperature measured by the second temperature sensor 42 . This allows the temperature of the cryopanel unit 20 to follow the target temperature. In two-stage temperature control, the first-stage cooling temperature is not directly controlled. In the two-stage temperature control, the first-stage cooling temperature is determined by the first-stage refrigerating capacity of the refrigerator 14 and the heat load from the outside to the first cooling stage 22 .

The controller 60 may be configured to control not only the cryopump 10 but also the gate valve 102 . The controller 60 may generate and send command signals to the gate valve 102 to open and close the gate valve 102 . The gate valve 102 may receive this command signal and open or close in response to the command signal. The gate valve 102 may generate a gate valve signal S indicating an open/closed state and transmit this to the controller 60 . The controller 60 may receive the gate valve signal S from the gate valve 102 and based on the gate valve signal S detect whether the gate valve 102 is closed.

The gate valve 102 may be controlled by a controller other than the controller 60 (for example, a controller higher than the controller 60 that controls the vacuum process apparatus). In this case, the controller 60 may receive the gate valve signal S from the controller controlling the gate valve 102 .

The internal configuration of the controller 60 is realized as a hardware configuration by elements and circuits such as a computer CPU and memory, and as a software configuration is achieved by a computer program or the like. It is drawn as a function block to be It should be understood by those skilled in the art that these functional blocks can be implemented in various ways by combining hardware and software.

For example, the controller 60 can be implemented by a combination of a CPU (Central Processing Unit), a processor (hardware) such as a microcomputer, and a software program executed by the processor (hardware). The software program may be a computer program for causing the controller 60 to execute the operating method of the cryopump 10 .

The operation of the cryopump 10 having the above configuration will be described below. Before operating the cryopump 10, the vacuum chamber 100 is first rough-pumped to a predetermined pressure (for example, about 100 Pa or about 10 Pa) by another appropriate roughing pump. During roughing of vacuum chamber 100, gate valve 102 is closed. After that (or in parallel with the roughing of the vacuum chamber 100), the cryopump 10 is activated. By driving the refrigerator 14, the first cooling stage 22 and the second cooling stage 24 are cooled to the first cooling temperature and the second cooling temperature, respectively. Therefore, the first cryopanel unit and the second cryopanel unit thermally coupled to them are also cooled to the first cooling temperature and the second cooling temperature, respectively. The gate valve 102 is opened and the evacuation of the vacuum chamber 100 by the cryopump 10 is started.

The inlet cryopanel 32 cools gases coming from the vacuum chamber toward the cryopump 10 . On the surface of the inlet cryopanel 32, a gas with sufficiently low vapor pressure (for example, 10 ⁻⁸ Pa or less) condenses at the first cooling temperature. This gas may be referred to as the first type gas. The first type gas is, for example, water vapor. Thus, the inlet cryopanel 32 can exhaust the first type gas. Part of the gas whose vapor pressure is not sufficiently low at the first cooling temperature enters the cryopump 10 through the inlet 12 . Alternatively, another portion of the gas is reflected off the inlet cryopanel 32 and returns to the vacuum chamber 100 without entering the cryopump 10 .

The gas entering the cryopump 10 is cooled by the cryopanel unit 20 . On the surface of the cryopanel unit 20, gas with sufficiently low vapor pressure (for example, 10 ⁻⁸ Pa or less) condenses at the second cooling temperature. This gas may be referred to as a second type gas. The second type gas is argon, for example. Thus, the cryopanel unit 20 can exhaust the second type gas.

A gas whose vapor pressure is not sufficiently low at the second cooling temperature is adsorbed by the adsorbent of the cryopanel unit 20 . This gas may be referred to as a third type gas. The third type gas is hydrogen, for example. Thus, the cryopanel unit 20 can exhaust the third type gas. Therefore, the cryopump 10 can exhaust various gases by condensation or adsorption to bring the degree of vacuum of the vacuum chamber to a desired level.

As the evacuation operation of the cryopump 10 continues, gas accumulates in the cryopump 10 . The cryopump 10 is regenerated in order to discharge the accumulated gas to the outside. Regeneration of the cryopump 10 generally includes heating, evacuation, and cooling down steps. In the heating step, the cryopump 10 is heated from a cryogenic temperature for evacuation operation to a regeneration temperature (eg, room temperature). Gas trapped within the cryopump 10 is vaporized. The second type gas and the third type gas can be easily discharged from the cryopump 10 during the temperature raising process. The first type gas is mainly discharged in the discharge process. After the discharge process is completed, the cool-down process is started. In the cooldown step, the cryopump 10 is recooled to cryogenic temperatures for evacuation operation. When the regeneration is completed in this way, the cryopump 10 can start the evacuation operation again.

The gate valve 102 is closed during regeneration of the cryopump 10 . After completion of regeneration, the gate valve 102 is opened again. However, the gate valve 102 does not have to be opened immediately upon completion of regeneration (that is, upon completion of the cool-down process). After completion of regeneration, the cryopump 10 can also take a standby state in which it is cooled to an extremely low temperature with the gate valve 102 closed. The cryopump 10 in the standby state can immediately start evacuating the vacuum chamber 100 by opening the gate valve 102 .

As described above, by opening the gate valve 102, a large amount of gas temporarily flows from the vacuum chamber 100 into the cryopump 10, which becomes a heat load on the refrigerator 14 and causes an overshoot in the cryopanel temperature. sell. Due to various factors, the second stage cryopanels may be more prone to temperature overshoot than the first stage cryopanels. This is simply because the second stage is cooler and has a greater temperature difference than the incoming room temperature gas. Also, in most cases, the second stage has a smaller heat capacity than the first stage (because the first stage is fitted with large components such as the radiation shield 30, it often has a large mass and thus a large heat capacity). The incoming main gas, a second gas, such as nitrogen, does not condense in the first stage, but condenses in the second stage. The latent heat generated with the phase change of the gas can raise the temperature of the second stage. An increase in temperature of the cryopanel may have an undesirable effect on the pumping performance of the cryopump in some cases.

In existing cryopump control, the refrigerating capacity of the refrigerator 14 is often suppressed for energy saving while the gate valve 102 that reduces the heat load from the vacuum chamber 100 to the cryopump 10 is closed. Under such control, it is effective to maintain the second stage temperature relatively high. As a result, the temperature of the second stage at the time of crossover tends to be high, and there is concern that temperature overshoot may easily occur.

In addition, the permissible range of cryopanel temperature is sometimes determined in advance as a unique setting in the vacuum process equipment. When it is detected that the allowable temperature range has been exceeded as a result of the above-described overshoot, the vacuum process apparatus can take actions to ensure safety, such as issuing an alert or emergency closing of the gate valve 102 . The vacuum process equipment has to wait until the cryopanel temperature returns to within the allowable range, which delays the start of the vacuum process.

Therefore, in this embodiment, in order to mitigate the overshoot of the cryopanel temperature that may occur during crossover, the controller 60 detects whether the gate valve 102 is closed and detects whether the gate valve 102 is closed. is configured to control the refrigerator 14 to increase the refrigerating capacity of the refrigerator 14 when the gate valve 102 is open compared to when the gate valve 102 is open.

FIG. 3 is a flow chart showing an example of a method of operating the cryopump 10 according to the embodiment. The controller 60 may periodically execute this process while the cryopump 10 is in operation.

As shown in FIG. 3, when this process is started, it is first determined whether or not the gate valve 102 is closed (S10). As an example, the controller 60 may be configured to receive a gate valve signal S indicating the open/close state of the gate valve 102 and detect whether the gate valve 102 is closed based on the gate valve signal S. As noted above, controller 60 may receive gate valve signal S from gate valve 102 or from another controller.

Alternatively, the controller 60 may be configured to acquire the heat load on the refrigerator 14 and detect whether the gate valve 102 is closed based on the acquired heat load. The heat load to refrigerator 14 primarily enters refrigerator 14 from vacuum chamber 100 through gate valve 102 . Therefore, the heat load on the refrigerator 14 when the gate valve 102 is closed is expected to be smaller than the heat load on the refrigerator 14 when the gate valve 102 is open. Therefore, when the heat load on the refrigerator 14 is below the heat load threshold, it is detected that the gate valve 102 is closed, and when the heat load on the refrigerator 14 exceeds the heat load threshold, the gate It can be detected that the valve 102 is open. The thermal load threshold may be obtained in advance based on the designer's empirical knowledge of the cryopump 10 or the designer's experiments, simulations, or the like, and may be stored in the controller 60 in advance.

The controller 60 refers to a map showing the relationship between the heat load on the refrigerator 14, the operating frequency of the refrigerator 14, and the cryopanel temperature, and based on the current operating frequency of the refrigerator 14 and the measured cryopanel temperature: may be configured to obtain the heat load to the refrigerator 14 by Such a map, also called a road map, may be obtained in advance based on the designer's empirical knowledge of the cryopump 10 or the designer's experiments, simulations, or the like, and may be stored in the controller 60 in advance.

For example, the first roadmap includes the heat load on each of the first and second stages of the refrigerator 14, the operating frequency of the refrigerator 14 under first-stage temperature control, and the second-stage cryopanel temperature represents the relationship between The controller 60 refers to the first roadmap during execution of the first stage temperature control, and based on the current operating frequency of the refrigerator 14 and the measured second stage cryopanel temperature, determines the first temperature of the refrigerator 14 . The heat load on each stage and second stage may be obtained. The second stage cryopanel temperature may be measured by a second temperature sensor 42 .

Alternatively, the relationship between the thermal load on each of the first stage and the second stage of the refrigerator 14, the operating frequency of the refrigerator 14 under two-stage temperature control, and the cryopanel temperature of the first stage is shown in FIG. 2 roadmaps may be used. The controller 60 refers to the second roadmap during execution of the two-stage temperature control, and based on the current operating frequency of the refrigerator 14 and the measured first stage cryopanel temperature, determines the first temperature of the refrigerator 14 . The heat load on each stage and second stage may be obtained. The first stage cryopanel temperature may be measured by the first temperature sensor 40 .

Note that the controller 60 may be configured to switch between the one-stage temperature control and the two-stage temperature control as necessary. When the cryopump 10 is in the evacuation operation, one-stage temperature control is normally performed. The controller 60 may execute two-stage temperature control in the standby state of the cryopump 10, switch from two-stage temperature control to one-stage temperature control at crossover, and execute one-stage temperature control during evacuation operation. good. Alternatively, the controller 60 senses whether the gate valve 102 is open, performs single-stage temperature control when the gate valve 102 is open, and performs two-stage temperature control when the gate valve 102 is closed. may

As shown in FIG. 3, when it is detected that the gate valve 102 is closed (Y in S10), the controller 60 increases the refrigerating capacity of the refrigerator 14 compared to when the gate valve 102 is open. The refrigerator 14 is controlled as follows (S12). On the other hand, if it is detected that the gate valve 102 is open (N of S10), such an increase in refrigerating capacity is not performed.

As an example of control for increasing the refrigerating capacity of the refrigerator 14, the controller 60 operates the refrigerator 14 at an operating frequency equal to or higher than the first lower limit when the gate valve 102 is open, and operates It may be configured to operate the refrigerator 14 at an operating frequency equal to or higher than a second lower limit value that is higher than the first lower limit value. In this way, if the gate valve 102 is closed while the refrigerator 14 is operating at an operating frequency lower than the second lower limit, the operating frequency of the refrigerator 14 is increased to the second lower limit. If the value of the operating frequency determined by the one-step temperature control or the two-step temperature control is greater than the second lower limit value, the operating frequency of the refrigerator 14 is increased to that value. In this way, the refrigerating capacity of refrigerator 14 when gate valve 102 is closed can be increased compared to when gate valve 102 is open.

The second lower limit value of the operating frequency is the upper limit value of the allowable operating frequency range of the refrigerator 14 or a predetermined value slightly smaller than it (for example, it may be larger than 80% or 90% of the upper limit value). may By doing so, the refrigerating capacity of the refrigerator 14 when the gate valve 102 is closed can be reliably increased compared to when the gate valve 102 is open.

As another example of control for increasing the cooling capacity of the refrigerator 14, the controller 60 adjusts the cooling temperature of the refrigerator 14 so that the cooling temperature measured by the temperature sensor matches the first target temperature when the gate valve 102 is open. The operation frequency is determined, and the operation frequency of the refrigerator 14 is determined so that the cooling temperature measured by the temperature sensor when the gate valve 102 is closed matches the second target temperature lower than the first target temperature. It may be configured to operate the refrigerator 14 at the same operating frequency. Even in this way, the refrigerator 14 can be controlled to increase the operating frequency of the refrigerator 14 when the gate valve 102 is closed compared to when the gate valve 102 is open.

For example, during single-stage temperature control, the controller 60 adjusts the operating frequency of the refrigerator 14 so that the cooling temperature measured by the first temperature sensor 40 matches the first target temperature when the gate valve 102 is open. and the operating frequency of the refrigerator 14 may be determined so as to match the cooling temperature measured by the first temperature sensor 40 with a second target temperature lower than the first target temperature when the gate valve 102 is closed. . In this case, the first target temperature may be selected from the range of 80K to 120K, for example. The second target temperature may be selected from temperatures above 60 K, for example.

Alternatively, during execution of the two-stage temperature control, the controller 60 adjusts the operating frequency of the refrigerator 14 so that the cooling temperature measured by the second temperature sensor 42 matches the first target temperature when the gate valve 102 is open. and the operating frequency of the refrigerator 14 may be determined so as to match the cooling temperature measured by the second temperature sensor 42 with a second target temperature lower than the first target temperature when the gate valve 102 is closed. . In this case, the first target temperature may be selected from the range of 12K to 20K, for example. The second target temperature may be selected from a range of 10K to 12K, for example.

During execution of the control for increasing the refrigerating capacity of the refrigerator 14, the controller 60 detects whether or not the gate valve 102 is open, and increases the refrigerating capacity of the refrigerator 14 when the gate valve 102 is open. may be terminated. In this way, the refrigerating capacity of the refrigerator 14 can be restored when the gate valve 102 is opened.

FIG. 4(a) is a diagram showing the operation of the cryopump according to the comparative example. As described above, in many existing cryopumps, closing the gate valve reduces the heat load from the vacuum chamber to the refrigerator of the cryopump. controlled. Therefore, as shown in FIG. 4(a), the operating frequency of the refrigerator is reduced while the gate valve is closed. At this time, the heat load on the refrigerator is also reduced, so the cryopanel temperature (for example, the second-stage cryopanel temperature) is maintained at the target temperature Ta. However, the situation changes when the gate valve opens. Due to the increased heat load on the refrigerator due to the crossover, the temperature of the cryopanel may temporarily rise significantly. That is, the cryopanel temperature overshoots. Since the cryopanel temperature deviates from the target temperature Ta in this way, the operating frequency of the refrigerator is increased, and thereafter the cryopanel temperature gradually returns to the target temperature Ta.

FIG. 4(b) is a diagram showing the operation of the cryopump according to the embodiment. According to the embodiment, the refrigerating capacity of the refrigerator 14 can be increased when the gate valve 102 is closed compared to when the gate valve 102 is open. As shown in FIG. 4(b), the operating frequency of the refrigerator 14 is increased while the gate valve is closed. Since the heat load on the refrigerator 14 is reduced at this time, the cryopanel temperature is lowered. After that, the gate valve 102 opens to increase the heat load on the refrigerator 14 and the cryopanel temperature rises. However, since the cryopanel temperature is sufficiently lowered in advance while the gate valve 102 is closed, the cryopanel temperature is expected to follow the target temperature Ta without greatly exceeding the target temperature Ta. In this manner, according to the embodiment, overshoot of the cryopanel temperature that may occur during crossover can be mitigated.

Most of the total operating time of the cryopump 10 is the evacuation operation of the vacuum chamber 100, during which the gate valve 102 is open. It is considered that the proportion of the time during which the gate valve 102 is closed in the total operating time of the cryopump 10 is very small. Therefore, in the cryopump 10 according to the embodiment, the power consumption may increase somewhat while the gate valve 102 is closed, but such time is expected to be very short, so there is no significant impact.

FIG. 5 is a flow chart showing another example of the operating method of the cryopump 10 according to the embodiment. Instead of detecting the opening/closing of the gate valve 102, it may be detected whether the regeneration of the cryopump 10 is completed. Therefore, the controller 60 may detect whether regeneration of the cryopump 10 has been completed, and control the refrigerator 14 to temporarily increase the refrigerating capacity of the refrigerator 14 following the completion of regeneration. . In this way, as in the above-described embodiments, overshoot of the cryopanel temperature that may occur during crossover can be mitigated.

As shown in FIG. 5, it is determined whether the regeneration of the cryopump 10 has been completed (S20). The controller 60 acquires the measured temperatures from the first temperature sensor 40 and the second temperature sensor 42 respectively in the cooling down process of regeneration, and uses the measured temperature of the first temperature sensor 40 as the first stage cryopanel 18 for evacuation operation. , and the measured temperature of the second temperature sensor 42 may be compared with the target cooling temperature of the second stage cryopanel unit 20 for the evacuation operation. The controller 60 continues the cool-down process if either of the temperatures measured by the first temperature sensor 40 and the second temperature sensor 42 has not yet reached the target cooling temperature. When the temperatures measured by the temperature sensors 42 reach the respective target cooling temperatures, it may be determined that the cool-down process, that is, the regeneration of the cryopump 10 has been completed.

When the regeneration of the cryopump 10 is completed (Y of S20), the controller 60 controls the refrigerator 14 to increase the refrigerating capacity of the refrigerator 14 (S22). The refrigerating capacity of the refrigerator 14 can be increased by increasing the operating frequency of the refrigerator 14, by lowering the target temperature in the one-stage temperature control, or by increasing the target temperature in the two-stage temperature control, as in the above-described embodiment. It may be achieved by lowering the temperature. On the other hand, if it is detected that the regeneration of the cryopump 10 has not been completed (N of S20), the refrigerating capacity is not increased.

The control to increase the refrigerating capacity of the refrigerator 14 may be executed until the gate valve 102 opens. In this case, the controller 60 may control the refrigerator 14 to increase the cooling capacity of the refrigerator 14 when the cryopump 10 is in the standby state. Alternatively, the control to increase the refrigerating capacity of refrigerator 14 may be executed over a predetermined period of time.

FIG. 6 is a block diagram schematically showing the configuration of a control device for the cryopump 10 according to another embodiment. In order to adjust the cooling capacity of the refrigerator 14, the refrigerator 14 may be provided with a heating device 62 such as an electric heater. The heating device 62 may be provided in the first cooling stage 22 , in the second cooling stage 24 , or in both the first cooling stage 22 and the second cooling stage 24 . Controller 60 may be configured to turn heating device 62 on and off and/or control the power output of heating device 62 .

The controller 60 operates the heating device 62 at a first output when the gate valve 102 is open and operates or operates the heating device 62 at a second output less than the first output when the gate valve 102 is closed. It may be configured not to allow By reducing the output of the heating device 62, the refrigerating capacity of the refrigerator 14 when the gate valve 102 is closed can be increased compared to when the gate valve 102 is open.

In the embodiment of FIG. 6, similarly to the embodiment of FIG. 2, the refrigerator 14 may include a refrigerator inverter 52 and be configured to have a variable operating frequency. In this case, for example, the operating frequency of the refrigerator 14 may be controlled by one-step temperature control or two-step temperature control, and the cooling capacity may be adjusted using the heating device 62 . Alternatively, in the embodiment of FIG. 6, refrigerator 14 may be driven at a constant operating frequency and may not include refrigerator inverter 52 .

The present invention has been described above based on the examples. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and that various design changes and modifications are possible, and that such modifications are within the scope of the present invention. By the way.

The present invention can be used in the field of cryopumps and cryopump operating methods.

10 cryopump, 14 refrigerator, 60 controller, 100 vacuum chamber, 102 gate valve.

Claims

A cryopump that can be attached to a vacuum chamber via a gate valve,
a refrigerator;
detecting whether or not the gate valve is closed, and controlling the refrigerator so as to increase the refrigerating capacity of the refrigerator when the gate valve is closed compared to when the gate valve is open; A cryopump, comprising: a controller configured to:
3. The controller is configured to receive a gate valve signal indicating an open/closed state of the gate valve, and to detect whether the gate valve is closed based on the gate valve signal. 1. The cryopump according to 1.
2. The controller according to claim 1, wherein the controller acquires a heat load to the refrigerator and detects whether or not the gate valve is closed based on the acquired heat load. cryopump.
The refrigerator is configured to have a variable operating frequency,
The controller operates the refrigerator at an operating frequency equal to or higher than a first lower limit when the gate valve is open, and operates at an operating frequency equal to or higher than a second lower limit greater than the first lower limit when the gate valve is closed. 4. The cryopump according to any one of claims 1 to 3, wherein the cryopump is configured to operate the refrigerator at an operating frequency.
The refrigerator is configured to have a variable operating frequency,
The cryopump further includes a temperature sensor that measures the cooling temperature of the refrigerator,
The controller determines the operating frequency of the refrigerator so that the cooling temperature measured by the temperature sensor matches the first target temperature when the gate valve is open, and determines the operating frequency of the refrigerator when the gate valve is closed. An operation frequency of the refrigerator is determined so that the cooling temperature measured by the temperature sensor matches a second target temperature lower than the first target temperature, and the refrigerator is operated at the determined operation frequency. 4. The cryopump according to any one of claims 1 to 3, wherein:
The refrigerator includes a heating device,
the controller operates the heating device at a first output when the gate valve is open and operates the heating device at a second output less than the first output when the gate valve is closed; or 5. A cryopump according to any one of claims 1 to 4, wherein the cryopump is configured to be inoperative.
A method of operating a cryopump, the cryopump being attachable to a vacuum chamber via a gate valve and comprising a refrigerator, the method comprising:
detecting whether the gate valve is closed;
and increasing the refrigerating capacity of the refrigerator when the gate valve is closed compared to when the gate valve is open.
a refrigerator;
a controller for detecting whether or not regeneration of the cryopump has been completed, and for controlling the refrigerator so as to temporarily increase the refrigerating capacity of the refrigerator following completion of the regeneration. cryopump.
A method of operating a cryopump, the cryopump comprising a refrigerator, the method comprising:
detecting whether regeneration of the cryopump is complete;
and temporarily increasing the refrigerating capacity of the refrigerator following completion of the regeneration.