Patent Application
20240392767
Certain embodiments of the present invention relate to a cryopump and a method of operating the cryopump.
A cryopump is a vacuum pump that captures gas molecules on a cryopanel cooled to a cryogenic temperature by condensation or adsorption and that exhausts the gas molecules. The cryopump is generally used to realize a clean vacuum environment which is required for a semiconductor circuit manufacturing process or the like.
According to an embodiment of the present invention, there is provided a cryopump capable of being mounted on a vacuum chamber via a gate valve, the cryopump including: a cryocooler; and a controller configured to detect whether or not the gate valve is closed, and to control the cryocooler such that a cooling capacity of the cryocooler when the gate valve is closed is increased compared to a cooling capacity of the cryocooler when the gate valve is opened.
According to another embodiment of the present invention, there is provided a method of operating a cryopump, in which the cryopump is capable of being mounted on a vacuum chamber via a gate valve and includes a cryocooler, the method including: detecting whether or not the gate valve is closed; and increasing a cooling capacity of the cryocooler when the gate valve is closed, compared to a cooling capacity of the cryocooler when the gate valve is opened.
According to still another embodiment of the present invention, there is provided a cryopump including: a cryocooler; and a controller that detects whether or not regeneration of the cryopump is completed and that controls the cryocooler to temporarily increase a cooling capacity of the cryocooler following the completion of the regeneration.
In order to sufficiently increase the degree of vacuum of a vacuum chamber as a preparation for starting a vacuum process in the vacuum chamber of vacuum process equipment, the vacuum chamber is first roughly pumped, and then is switched to evacuation by a cryopump. During the rough pumping of the vacuum chamber, a gate valve provided between the vacuum chamber and the cryopump is closed, and is opened to start the evacuation by the cryopump. At this time, the ultimate pressure in 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, and this becomes a heat load on a cryocooler that cools the cryopump, which may cause an overshoot in a cryopanel temperature. Such a temperature rise is also referred to as a crossover. The temperature rise of the cryopanel may undesirably affect the exhaust performance of the cryopump in some cases.
In addition, in the vacuum process equipment, an allowable range of the cryopanel temperature may be determined in advance as a unique setting. As a result of the overshoot described above, when it is detected that the allowable temperature range is exceeded, an operation for securing safety, such as issuing an alert or urgently closing the gate valve, can be executed by the vacuum process equipment. The vacuum process equipment waits until the cryopanel temperature returns to the allowable range, and the start of the vacuum process is delayed accordingly.
It is desirable to provide a cryopump capable of alleviate an overshoot of a cryopanel temperature that may occur at the time of a crossover.
Any combinations of the components described above or mutual replacement of the components or expressions of the present invention in methods, devices, systems, or the like are also effective as embodiments of the present invention.
Hereinafter, an embodiment for carrying out the present invention will be described in detail with reference to the drawings. In the description and drawings, identical or equivalent components, members, and processing are denoted by the same reference numerals, and overlapping description is omitted as appropriate. The scale or shape of each part that is shown in the drawings is conveniently set for ease of description and is not limitedly interpreted unless otherwise specified. The embodiments are exemplary and do not limit the scope of the present invention in any way. All features or combinations thereof described in the embodiments are not essential to the invention.
The cryopump 10 can be mounted on a vacuum chamber 100 of, for example, an ion implanter, a sputtering apparatus, a vapor deposition apparatus, or other vacuum process equipment via a gate valve 102. In
The cryopump 10 is mounted on the vacuum chamber 100 via the gate valve 102, and is used to increase the degree of vacuum inside the vacuum chamber 100 to a level required for a desired vacuum process. The cryopump 10 includes a cryopump intake port (hereinafter also simply referred to as an “intake port”) 12 for receiving a gas to be exhausted from the vacuum chamber 100. A 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, there is a case where the terms “axial direction” and “radial direction” are used in order to express the positional relationship between components of the cryopump 10 in an easily understandable manner. The axial direction of the cryopump 10 represents a direction passing through the intake port 12 (that is, a direction along the center axis of the cryopump 10, and an up-down direction in the drawing), and the radial direction represents a direction along the intake port 12 (a direction perpendicular to the center axis of the cryopump 10, and a left-right direction in the drawing). For convenience, with respect to the axial direction, there is a case where the side relatively close to the intake port 12 is referred to as an “upper side” and the side relatively distant from the intake port 12 is referred to as a “lower side”. That is, there is a case where the side relatively distance from the bottom of the cryopump 10 is referred to as an “upper side” and the side relatively close to the bottom of the cryopump 10 is referred to as a “lower side”. With respect to the radial direction, a position close to the center of the intake port 12 may be referred to as “inner side”, and a position close to the peripheral edge of the intake port 12 may be referred to as “outer side”. Such expressions are not related to the disposition when the cryopump 10 is mounted on the vacuum chamber 100. For example, the cryopump 10 may be mounted on the vacuum chamber 100 with the intake port 12 facing downward in the vertical direction.
Further, there is a case where a direction surrounding the axial direction is referred to as a “circumferential direction”. The circumferential direction is a second direction along the intake port 12 and is a tangential direction orthogonal to the radial direction.
The cryopump 10 includes a cryocooler 14, a cryopump container 16, a first-stage cryopanel 18, and a cryopanel unit 20. The first-stage cryopanel 18 may be referred to as a high-temperature cryopanel part or a 100 K part. The cryopanel unit 20 is a cryopanel of a second stage and may be referred to as a low-temperature cryopanel part or a 10 K part.
The cryocooler 14 is a cryocooler such as a Gifford McMahon type cryocooler (a so-called GM cryocooler), for example. The cryocooler 14 is a two-stage cryocooler, and includes a first cooling stage 22 and a second cooling stage 24. The cryocooler 14 is configured to cool the first cooling stage 22 to a first cooling temperature and cool 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 a temperature in a range of about 60 K to 120 K, preferably, in a range of 80 K to 100 K, and the second cooling stage 24 is cooled to a temperature in a range of about 10 K to 20 K. The first cooling stage 22 and the second cooling stage 24 may be referred to as a high-temperature cooling stage and a low-temperature cooling stage, respectively.
Further, the cryocooler 14 includes a cryocooler structure part 21 that structurally supports the second cooling stage 24 on the first cooling stage 22 and structurally supports the first cooling stage 22 on a room temperature part 26 of the cryocooler 14. Therefore, the cryocooler structure part 21 includes a first cylinder 23 and a second cylinder 25 that extend coaxially along the radial direction. The first cylinder 23 connects the room temperature part 26 of the cryocooler 14 to the first cooling stage 22. The 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 formed of a high thermal conductivity metal material such as copper (for example, pure copper), and the first cylinder 23 and the second cylinder 25 are formed of other metal materials such as stainless steel. The room temperature part 26, the first cylinder 23, the first cooling stage 22, the second cylinder 25, and the second cooling stage 24 are linearly arranged in a row in this order.
A first displacer and a second displacer (not shown) are reciprocally disposed in the interiors of the first cylinder 23 and the second cylinder 25, respectively. A first regenerator and a second regenerator (not shown) are respectively incorporated into the first displacer and the second displacer. Further, the room temperature part 26 has a drive mechanism (not shown) for reciprocating the first displacer and the second displacer. The drive mechanism includes a cryocooler motor 50 (described later). Further, the drive mechanism includes a flow path switching mechanism that switches a flow path for a working gas (for example, helium) to periodically repeat the supply and discharge of the working gas to and from the interior of the cryocooler 14.
The cryocooler 14 is connected to a compressor (not shown) for the working gas. The cryocooler 14 cools the first cooling stage 22 and the second cooling stage 24 by expanding the working gas pressurized by the compressor in the interior thereof. The expanded working gas is recovered to the compressor and pressurized again. The cryocooler 14 generates cold by repeating a heat cycle including the supply and discharge of the working gas and the reciprocation of the first displacer and the second displacer in synchronization with the supply and discharge of the working gas.
The cryopump 10 shown in the drawing is a so-called horizontal cryopump. The horizontal cryopump is generally a cryopump in which the cryocooler 14 is disposed to intersect (usually, be orthogonal to) the center axis of the cryopump 10. The present invention can similarly be applied to a so-called vertical cryopump. The vertical cryopump is a cryopump in which a cryocooler is disposed along the axial direction of the cryopump.
The cryopump container 16 is a casing of the cryopump 10 that accommodates the cryocooler 14, the first-stage cryopanel 18, and the cryopanel unit 20, and is configured to maintain the airtightness of the internal space of the cryopump 10. The cryopump container 16 has an intake port flange 16a that extends outward in the radial direction over the entire circumference from the front end thereof. The intake port 12 is defined on the radial inner side by the intake port flange 16a. In addition, the cryopump container 16 includes a container body portion 16b extending in the axial direction from the intake port flange 16a, a container bottom portion 16c that closes the container body portion 16b on a side opposite to the intake port 12, and a cryocooler accommodation cylinder 16d extending laterally between the intake port flange 16a and the container bottom portion 16c.
An end portion of the cryocooler accommodation cylinder 16d on the side opposite to the container body portion 16b is mounted on the room temperature part 26 of the cryocooler 14, and thereby, the low temperature sections (that is, the first cylinder 23, the first cooling stage 22, the second cylinder 25, and the second cooling stage 24) of the cryocooler 14 are disposed in the cryopump container 16 in a non-contact manner with the cryopump container 16. The first cylinder 23 is disposed inside the cryocooler accommodation cylinder 16d, and the first cooling stage 22, the second cylinder 25, and the second cooling stage 24 are disposed inside the container body portion 16b. The first-stage cryopanel 18 and the cryopanel unit 20 are also disposed in the container body portion 16b.
The first-stage cryopanel 18 includes a radiation shield 30 and an inlet cryopanel 32, and surrounds the cryopanel unit 20. The first-stage cryopanel 18 provides a cryogenic surface for protecting the cryopanel unit 20 from the radiant heat from the outside of the cryopump 10 or the cryopump container 16. The first-stage cryopanel 18 is thermally coupled to the first cooling stage 22 and is cooled to the first cooling temperature. The first-stage cryopanel 18 has a gap between the first-stage cryopanel 18 and 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 container 16.
The radiation shield 30 is provided to protect the cryopanel unit 20 from the radiant heat of the cryopump container 16. The radiation shield 30 extends in a tubular shape (for example, a cylindrical shape) in the axial direction from the intake port 12 toward the container bottom portion 16c inside the cryopump container 16. The radiation shield 30 is open on the intake port 12 side and is closed on the container bottom portion 16c side. The radiation shield 30 is disposed between the cryopump container 16 and the cryopanel unit 20, and surrounds the cryopanel unit 20. The radiation shield 30 has a diameter slightly smaller than that of the cryopump container 16, and a shield outer gap 31 is formed between the radiation shield 30 and the cryopump container 16. Therefore, the radiation shield 30 is not in contact with the cryopump container 16.
The first cooling stage 22 of the cryocooler 14 is directly mounted on the side portion outer surface of the radiation shield 30. In this way, the radiation shield 30 is thermally coupled to the first cooling stage 22 to be cooled to the first cooling temperature. The radiation shield 30 may be mounted on the first cooling stage 22 via an appropriate heat transfer member. In addition, the second cooling stage 24 and the second cylinder 25 of the cryocooler 14 are inserted into the radiation shield 30 from the side portion of the radiation shield 30.
The inlet cryopanel 32 is provided in the intake port 12 in order to protect the cryopanel unit 20 from the radiant heat from a heat source outside the cryopump 10 (for example, a heat source in the vacuum chamber on which the cryopump 10 is mounted). The inlet cryopanel 32 is thermally coupled to the first cooling stage 22 via the radiation shield 30, and is cooled to the first cooling temperature, similarly to the radiation shield 30. Therefore, a gas (for example, moisture) that is condensed at the first cooling temperature is captured on the surface.
The cryopanel unit 20 includes a plurality of cryopanels, each of which is thermally coupled to the second cooling stage 24 and is cooled to the second cooling temperature lower than the first cooling temperature. These cryopanels may be arranged in the axial direction from the intake port 12 toward the container bottom portion 16c, as shown in the drawing. An adsorbent (for example, activated carbon) may be provided on at least a part of the surface of the cryopanel to capture a non-condensable gas (for example, hydrogen) by adsorption. The cryopanel unit 20 is disposed below the inlet cryopanel 32 to be surrounded by the radiation shield 30 in the cryopump container 16. The cryopanel unit 20 is not in contact with the radiation shield 30 and the inlet cryopanel 32. Since the configuration of the cryopanel unit 20, such as the disposition or the shape of the cryopanel, can adopt various known configurations as appropriate, the configuration will not be described in detail here.
The gate valve 102 is installed between the cryopump 10 and the vacuum chamber 100. The gate valve 102 includes a valve housing 104 and a valve plate 106. The valve housing 104 forms a communication path that connects an opening portion of the vacuum chamber 100 to the intake port 12 of the cryopump 10. The valve housing 104 has a flange portion on each of both sides of the communication path, and the flange portion on one side is mounted on the flange portion of the vacuum chamber 100 that surrounds the opening portion of the vacuum chamber 100, and the flange portion on the opposite side is mounted on the intake port flange 16a.
The gate valve 102 is closed as necessary, for example, when maintenance of the vacuum chamber 100 or the cryopump 10 is performed. The flange portion on the intake port flange 16a side of the valve housing 104 also serves as a valve seat portion of the gate valve 102, and the valve plate 106 serving as a valve body is brought into close contact with the valve seat portion, whereby the gate valve 102 is closed. At this time, a gas flow from the vacuum chamber 100 to the cryopump 10 through the intake port 12 is blocked. The cryopump 10 is isolated from the vacuum chamber 100, and the internal space of the cryopump 10 is held in an airtight manner.
The gate valve 102 is opened to perform evacuation of the vacuum chamber 100 by the cryopump 10. A valve plate accommodation portion 108 is provided in the valve housing 104, and when the valve plate 106 is separated from the valve seat portion of the valve housing 104 and is accommodated in the valve plate accommodation portion 108, as shown by a one-dot chain line in
As shown in
The cryocooler 14 includes the cryocooler motor 50 that drives the cryocooler 14, and a cryocooler inverter 52 that controls an operation frequency of the cryocooler 14. The operation frequency (also referred to as an operation speed) of the cryocooler 14 represents the operation frequency or the rotation speed of the cryocooler motor 50, the operation frequency of the cryocooler inverter 52, the frequency of the heat cycle, or any of these. The frequency of the heat cycle is the number of times of the heat cycle that is performed in the cryocooler 14 per unit time.
In addition, the cryopump 10 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 may be connected to the first temperature sensor 40 to receive the first measured temperature signal T1 from the first temperature sensor 40 and connected to the second temperature sensor 42 to receive the second measured temperature signal T2 from the second temperature sensor 42. The cryocooler inverter 52 described above may be provided in the controller 60.
The controller 60 may be configured to control the cryocooler 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. For example, the controller 60 may control the operation frequency of the cryocooler 14 by feedback-control to minimize a deviation between the target temperature of the first cooling stage 22 and the measured temperature of the first temperature sensor 40.
The target temperature of the first cooling stage 22 is usually set to a constant value. The target temperature of the first cooling stage 22 is determined, for example, as a specification in accordance with a process that is performed in the vacuum chamber 100 on which the cryopump 10 is mounted. The target temperature may be changed as necessary during the operation of the cryopump 10.
The controller 60 may determine an operation frequency F of the cryocooler motor 50 (for example, by PID control) as a function of the deviation between the measured temperature and the target temperature. The operation frequency F of the cryocooler motor 50 is determined within a predetermined operation frequency range. The operation frequency range is defined by an upper limit and a lower limit of a predetermined operation frequency. The controller 60 outputs the determined operation frequency F to the cryocooler inverter 52.
The cryocooler inverter 52 is configured to provide variable frequency control of the cryocooler motor 50. The cryocooler inverter 52 converts the input electric power to have the operation frequency F input from the controller 60. The input electric power to the cryocooler inverter 52 is supplied from a cryocooler power source (not shown). The cryocooler power source may be a commercial power source. The cryocooler inverter 52 outputs the converted electric power to the cryocooler motor 50. In this way, the cryocooler motor 50 is driven at the operation frequency F determined by the controller 60 and output from the cryocooler inverter 52.
When the heat load on the cryopump 10 increases, the temperature of the first cooling stage 22 may increase. In a case where the measured temperature of the first temperature sensor 40 is higher than the target temperature, the controller 60 increases the operation frequency of the cryocooler 14. As a result, the frequency of the heat cycle in the cryocooler 14 is also increased, and the first-stage cryopanel 18 and the first cooling stage 22 are cooled toward the target temperature. On the contrary, in a case where the measured temperature of the first temperature sensor 40 is lower than the target temperature, the operation frequency of the cryocooler 14 is decreased, and the first cooling stage 22 is heated toward the target temperature. In this way, the temperature of the first-stage cryopanel 18 can be kept in the temperature range near the target temperature. Since the operation frequency of the cryocooler 14 can be appropriately adjusted according to the heat load, such control helps to reduce the power consumption of the cryopump 10.
Hereinafter, controlling the cryocooler 14 such that the temperature of the first cooling stage 22 follows the target temperature may be referred to as “first-stage temperature control”. In the first-stage temperature control, a second-stage cooling temperature is not directly controlled. That is, as a result of the first-stage temperature control, the second cooling stage 24 and the cryopanel unit 20 are cooled to a temperature determined by the cooling capacity of the second stage of the cryocooler 14 and the heat load from the outside to the second cooling stage 24.
Similarly, the controller 60 can also execute so-called “second-stage temperature control” in which the cryocooler 14 is controlled such that the temperature of the second cooling stage 24 follows the target temperature. In this case, the controller 60 may control the operation frequency of the cryocooler 14 by feedback-control to minimize the deviation between the target temperature of the second cooling stage 24 and the measured temperature of the second temperature sensor 42. In this way, the temperature of the cryopanel unit 20 can be made to follow the target temperature. In the second-stage temperature control, the first-stage cooling temperature is not directly controlled. In the second-stage temperature control, a first-stage cooling temperature is determined by the cooling capacity of the first stage of the cryocooler 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 a command signal for opening and closing the gate valve 102 and transmit the command signal to the gate valve 102. The gate valve 102 may receive the command signal and be opened or closed in response to the command signal. The gate valve 102 may generate a gate valve signal S indicating an opening/closing state and transmit the gate valve signal S to the controller 60. The controller 60 may receive the gate valve signal S from the gate valve 102, and detect whether or not the gate valve 102 is closed, based on the gate valve signal S.
The gate valve 102 may be controlled by a controller (for example, a controller of a higher level than the controller 60 that controls the vacuum process equipment) different from the controller 60. In this case, the controller 60 may receive the gate valve signal S from the controller that controls the gate valve 102.
An internal configuration of the controller 60 is realized by an element or a circuit including a CPU or a memory of a computer as a hardware configuration and is realized by a computer program or the like as a software configuration. However, in the drawing, the internal configuration is depicted as a functional block that is realized by cooperation of the hardware configuration and the software configuration, as appropriate. Those skilled in the art will understand that these functional blocks can be realized in various ways by combining hardware and software.
For example, the controller 60 can be implemented by a combination of a processor (hardware) such as a central processing unit (CPU) or a microcomputer and a software program which is executed by the processor (hardware). The software program may be a computer program for causing the controller 60 to execute the method of operating the cryopump 10.
The operation of the cryopump 10 having the configuration described above will be described below. When the cryopump 10 operates, first, the vacuum chamber 100 is roughly pumped to a predetermined pressure (for example, about 100 Pa or about 10 Pa) by another suitable rough pump before the operation of the cryopump 10. During the rough pumping of the vacuum chamber 100, the gate valve 102 is closed. Thereafter (or in parallel with the rough pumping of the vacuum chamber 100), the cryopump 10 is operated. The first cooling stage 22 and the second cooling stage 24 are respectively cooled to the first cooling temperature and the second cooling temperature by driving of the cryocooler 14. Therefore, a first cryopanel unit and a second cryopanel unit thermally coupled to the first cooling stage 22 and the second cooling stage 24 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 a gas that comes flying from the vacuum chamber toward the cryopump 10. A gas having a sufficiently low vapor pressure (for example, 10−8 Pa or lower) at the first cooling temperature condenses on the surface of the inlet cryopanel 32. This gas may be referred to as a type 1 gas. The type 1 gas is, for example, water vapor. In this way, the inlet cryopanel 32 can exhaust the type 1 gas. A part of the gas having a vapor pressure that is not sufficiently low at the first cooling temperature enters the cryopump 10 from the intake port 12. Alternatively, the other part of the gas is reflected by the inlet cryopanel 32, and returns to the vacuum chamber 100 without entering the cryopump 10.
The gas that has entered the cryopump 10 is cooled by the cryopanel unit 20. A gas having a sufficiently low vapor pressure (for example, 10−8 Pa or lower) at the second cooling temperature condenses on the surface of the cryopanel unit 20. This gas may be referred to as a type 2 gas. The type 2 gas is, for example, argon. In this way, the cryopanel unit 20 can exhaust the type 2 gas.
The gas having a vapor pressure that 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 type 3 gas. The type 3 gas is, for example, hydrogen. In this way, the cryopanel unit 20 can exhaust the type 3 gas. Therefore, the cryopump 10 can exhaust various gases by condensation or adsorption and can make the degree of vacuum of the vacuum chamber reach a desired level.
The evacuation operation of the cryopump 10 is continued, so that a gas is accumulated in the cryopump 10. The regeneration of the cryopump 10 is performed in order to discharge the accumulated gas to the outside. The regeneration of the cryopump 10 generally includes a temperature rising process, a discharge process, and a cool-down process. In the temperature rising process, the cryopump 10 is heated from a cryogenic temperature for the evacuation operation to a regeneration temperature (for example, room temperature). The gas captured inside the cryopump 10 is vaporized. The type 2 gas and the type 3 gas can be easily discharged from the cryopump 10 in the temperature rising process. In the discharge process, mainly the type 1 gas is discharged. When the discharge process is completed, the cool-down process is started. In the cool-down process, the cryopump 10 is re-cooled to the cryogenic temperatures for the evacuation operation. When the regeneration is completed in this way, the cryopump 10 can start the evacuation operation again.
During the regeneration of the cryopump 10, the gate valve 102 is closed. The gate valve 102 is opened again after the regeneration is completed. However, the gate valve 102 does not need to be immediately opened at the point in time when the regeneration is completed (that is, the point in time when the cool-down process is completed). The cryopump 10 after the regeneration is completed can also take a standby state in which the cryopump 10 is cooled to the cryogenic temperature in a state where the gate valve 102 is closed. The cryopump 10 in the standby state can immediately start the evacuation of the vacuum chamber 100 by opening the gate valve 102.
As described above, when the gate valve 102 is opened, a large amount of gas temporarily flows from the vacuum chamber 100 to the cryopump 10, and this may cause an overshoot in the cryopanel temperature as a heat load on the cryocooler 14. Due to various factors, there is a case where a temperature overshoot is likely to occur in the cryopanel of the second stage, compared to the cryopanel of the first stage. This is simply because the temperature of the second stage is lower and the temperature difference between the second stage and an inflow gas at room temperature is large. In addition, in most cases, the second stage has a smaller heat capacity than the first stage (since a large component such as the radiation shield 30 is mounted on the first stage, the mass and the heat capacity are often large). The type 2 gas such as nitrogen, which is a main gas that flows in, is not condensed in the first stage, but is condensed in the second stage. The latent heat that is generated due to a phase change of the gas can raise the temperature of the second stage. The temperature rise of the cryopanel may undesirably affect the exhaust performance of the cryopump in some cases.
In the existing cryopump control, the cooling capacity of the cryocooler 14 is often suppressed for energy saving during the closing of the gate valve 102 in which the heat load from the vacuum chamber 100 to the cryopump 10 is reduced. Under such control, it is effective to maintain the second-stage temperature relatively high. As a result, the second-stage temperature at the point in time of the generation of the crossover tends to be high, and there is a concern that the temperature overshoot may easily occur.
In addition, as a unique setting in the vacuum process equipment, an allowable range of the cryopanel temperature may be determined in advance. As a result of the overshoot described above, when it is detected that the allowable temperature range is exceeded, an operation for securing safety, such as issuing an alert or urgently closing the gate valve 102, can be executed by the vacuum process equipment. The vacuum process equipment waits until the cryopanel temperature returns to the allowable range, and the start of the vacuum process is delayed accordingly.
Therefore, in this embodiment, in order to alleviate the overshoot of the cryopanel temperature that may occur at the time of a crossover, the controller 60 is configured to detect whether or not the gate valve 102 is closed, and to control the cryocooler 14 such that the cooling capacity of the cryocooler 14 when the gate valve 102 is closed is increased compared to the cooling capacity of the cryocooler 14 when the gate valve 102 is opened.
As shown in
As another method, the controller 60 may be configured to acquire a heat load on the cryocooler 14 and to detect whether or not the gate valve 102 is closed, based on the acquired heat load. The heat load on the cryocooler 14 mainly enters the cryocooler 14 from the vacuum chamber 100 through the gate valve 102. Therefore, it is expected that the heat load on the cryocooler 14 when the gate valve 102 is closed becomes smaller than the heat load on the cryocooler 14 when the gate valve 102 is opened. Therefore, it is possible to detect that the gate valve 102 is closed in a case where the heat load on the cryocooler 14 falls below a heat load threshold, and to detect that the gate valve 102 is opened in a case where the heat load on the cryocooler 14 exceeds the heat load threshold. The heat load threshold may be acquired in advance based on empirical knowledge of a designer of the cryopump 10 or experiments or simulations by the designer, and be stored in the controller 60 in advance.
The controller 60 may be configured to refer to a map indicating the relationship between the heat load on the cryocooler 14, the operation frequency of the cryocooler 14, and the cryopanel temperature, and to acquire the heat load on the cryocooler 14, based on the current operation frequency of the cryocooler 14 and the measured cryopanel temperature. Such a map is also referred to as a roadmap, and may be acquired in advance based on empirical knowledge of a designer of the cryopump 10 or experiments or simulations by the designer, and be stored in the controller 60 in advance.
For example, a first roadmap represents the relationship between the heat load on each of the first stage and the second stage of the cryocooler 14, and the operation frequency of the cryocooler 14 and the cryopanel temperature of the second stage under the first-stage temperature control. The controller 60 may refer to the first roadmap during the execution of the first-stage temperature control, and acquire the heat load on each of the first stage and the second stage of the cryocooler 14, based on the current operation frequency of the cryocooler 14 and the measured cryopanel temperature of the second stage. The cryopanel temperature of the second stage may be measured by the second temperature sensor 42.
Alternatively, a second roadmap representing the relationship between the heat load on each of the first stage and the second stage of the cryocooler 14, and the operation frequency of the cryocooler 14 and the cryopanel temperature of the first stage under the second-stage temperature control may be used. The controller 60 may refer to the second roadmap during the execution of the second-stage temperature control, and acquire the heat load on each of the first stage and the second stage of the cryocooler 14, based on the current operation frequency of the cryocooler 14 and the measured cryopanel temperature of the first stage. The cryopanel temperature of the first stage may be measured by the first temperature sensor 40.
The controller 60 may be configured to switch between the first-stage temperature control and the second-stage temperature control and execute the switched temperature control, as necessary. When the cryopump 10 is performing the evacuation operation, normally, the first-stage temperature control is executed. The controller 60 may execute the second-stage temperature control in the standby state of the cryopump 10, switch from the second-stage temperature control to the first-stage temperature control at the time of the crossover, and execute the first-stage temperature control during the evacuation operation. Alternatively, the controller 60 may detect whether or not the gate valve 102 is opened, and execute the first-stage temperature control when the gate valve 102 is opened, and execute the second-stage temperature control when the gate valve 102 is closed.
As shown in
As an example of the control to increase the cooling capacity of the cryocooler 14, the controller 60 may be configured to operate the cryocooler 14 at an operation frequency equal to or higher than the first lower limit value when the gate valve 102 is opened, and to operate the cryocooler 14 at an operation frequency equal to or higher than the second lower limit value larger than the first lower limit value when the gate valve 102 is closed. In this way, when the cryocooler 14 is operated at the operation frequency lower than the second lower limit value, when the gate valve 102 is closed, the operation frequency of the cryocooler 14 is increased to the second lower limit value. When the value of the operation frequency that is determined by the first-stage temperature control or the second-stage temperature control is larger than the second lower limit value, the operation frequency of the cryocooler 14 is increased to the value. In this way, the cooling capacity of the cryocooler 14 when the gate valve 102 is closed can be increased compared to the cooling capacity of the cryocooler 14 when the gate valve 102 is opened.
The second lower limit value of the operation frequency may be an upper limit value of the allowable operation frequency range of the cryocooler 14 or a predetermined value slightly smaller than the upper limit value (for example, the predetermined value may be larger than 80% or 90% of the upper limit value). In this way, the cooling capacity of the cryocooler 14 when the gate valve 102 is closed can be reliably increased compared to the cooling capacity of the cryocooler 14 when the gate valve 102 is opened.
As another example of the control to increase the cooling capacity of the cryocooler 14, the controller 60 may be configured to determine the operation frequency of the cryocooler 14 such that the cooling temperature measured by the temperature sensor coincides with the first target temperature when the gate valve 102 is opened, and to determine the operation frequency of the cryocooler 14 such that the cooling temperature measured by the temperature sensor coincides with the second target temperature lower than the first target temperature when the gate valve 102 is closed, and to operate the cryocooler 14 at the determined operation frequency. Even in this way, the cryocooler 14 can be controlled to increase the operation frequency of the cryocooler 14 when the gate valve 102 is closed, compared to the operation frequency of the cryocooler 14 when the gate valve 102 is opened.
For example, during the execution of the first-stage temperature control, the controller 60 may determine the operation frequency of the cryocooler 14 such that the cooling temperature measured by the first temperature sensor 40 coincides with the first target temperature when the gate valve 102 is opened, and determine the operation frequency of the cryocooler 14 such that the cooling temperature measured by the first temperature sensor 40 coincides with the 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, for example, a range of 80 K to 120 K. The second target temperature may be selected from, for example, a temperature of 60 K or higher.
Alternatively, during the execution of the second-stage temperature control, the controller 60 may determine the operation frequency of the cryocooler 14 such that the cooling temperature measured by the second temperature sensor 42 coincides with the first target temperature when the gate valve 102 is opened, and determine the operation frequency of the cryocooler 14 such that the cooling temperature measured by the second temperature sensor 42 coincides with the 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, for example, a range of 12 K to 20 K. The second target temperature may be selected from, for example, a range of 10 K to 12 K.
In addition, during the execution of the control to increase the cooling capacity of the cryocooler 14, the controller 60 may detect whether or not the gate valve 102 is opened, and end the increase of the cooling capacity of the cryocooler 14 in a case where the gate valve 102 is opened. In this way, when the gate valve 102 is opened, the cooling capacity of the cryocooler 14 can be restored.
Most of the total operation time of the cryopump 10 is the evacuation operation of the vacuum chamber 100, and the gate valve 102 is opened during this time. It is considered that the proportion of the time when the gate valve 102 is closed in the total operation time of the cryopump 10 is very small. Therefore, in the cryopump 10 according to the embodiment, the power consumption during the closing of the gate valve 102 may increase to some extent. However, since such time is expected to be very short, there is no significant influence on the majority.
As shown in
In a case where the regeneration of the cryopump 10 is completed (Y in S20), the controller 60 controls the cryocooler 14 to increase the cooling capacity of the cryocooler 14 (S22). The increase of the cooling capacity of the cryocooler 14 may be realized by lowering the target temperature in the first-stage temperature control or by lowering the target temperature in the second-stage temperature control, by increasing the operation frequency of the cryocooler 14, as with the embodiment described above. On the other hand, in a case where it is detected that the regeneration of the cryopump 10 is not completed (N in S20), the increase of the cooling capacity is not performed.
The control to increase the cooling capacity of the cryocooler 14 may be executed until the gate valve 102 is opened. In this case, the controller 60 may control the cryocooler 14 to increase the cooling capacity of the cryocooler 14 when the cryopump 10 is in the standby state. Alternatively, the control to increase the cooling capacity of the cryocooler 14 may be executed for a predetermined time.
The controller 60 may be configured to operate the heating device 62 at a first output when the gate valve 102 is opened, and to operate the heating device 62 at a second output lower than the first output or not to operate the heating device 62 when the gate valve 102 is closed. By reducing the output of the heating device 62, the cooling capacity of the cryocooler 14 when the gate valve 102 is closed can be increased compared to the cooling capacity of the cryocooler 14 when the gate valve 102 is opened.
Also in the embodiment of
The present invention has been described above based on the examples. It will be understood by those skilled in the art that the present invention is not limited to the above embodiments, various design changes can be made, various modification examples are possible, and such modification examples are also within the scope of the present invention.
The present invention can be used in the field of the cryopump and the method of operating the cryopump.
It should be understood that the invention is not limited to the above-described embodiment, but may be modified into various forms on the basis of the spirit of the invention. Additionally, the modifications are included in the scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-024015 | Feb 2022 | JP | national |
This is a bypass continuation of International PCT Application No. PCT/JP2023/002219, filed on Jan. 25, 2023, which claims priority to Japanese Patent Application No. 2022-024015, filed on Feb. 18, 2022, which are incorporated by reference herein in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2023/002219 | Jan 2023 | WO |
| Child | 18797599 | US |
