Patent Application
20250003400
Certain embodiments of the present invention relate to a method for regenerating a cryopump and a 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. Since the cryopump is a so-called gas accumulation type vacuum pump, regeneration to periodically exhaust the captured gas to the outside is required.
According to an embodiment of the present invention, there is provided a method for regenerating a cryopump, in which the cryopump includes a cryopanel and a cryopump container that accommodates the cryopanel, the method including: raising a temperature of the cryopanel from a cryogenic temperature to a temperature rising completion temperature; and completing regeneration of the cryopump in a state where the temperature of the cryopanel is raised to the temperature rising completion temperature, in which the completion includes acquiring a history of a pressure rise rate in the cryopump container by repeating supply of a purge gas to the cryopump container, rough pumping of the cryopump container, and measurement of the pressure rise rate, and determining whether or not to complete the regeneration of the cryopump, based on the acquired history of the pressure rise rate.
According to another embodiment of the present invention, there is provided a cryopump including: a cryopanel; a cryopump container that accommodates the cryopanel; a heat source that raises a temperature of the cryopanel; a purge valve that supplies a purge gas to the cryopump container; a rough valve that exhausts a gas from the cryopump container to a rough pump; a pressure sensor that measures a pressure in the cryopump container; and a controller configured to operate the heat source to raise the temperature of the cryopanel from a cryogenic temperature to a temperature rising completion temperature, and to complete regeneration of the cryopump in a state where the temperature of the cryopanel is raised to the temperature rising completion temperature, in which the controller is configured to acquire a history of a pressure rise rate in the cryopump container by operating the purge valve, the rough valve, and the pressure sensor to repeat supply of a purge gas to the cryopump container, rough pumping of the cryopump container, and measurement of the pressure rise rate, and determine whether or not to complete the regeneration of the cryopump, based on the acquired history of the pressure rise rate.
In some cases, the cryopump is removed from a vacuum process device for replacement or maintenance. As preparation for the removal work, the temperature of the cryopump is raised to an appropriate temperature (for example, room temperature). The gas captured inside the cryopump is vaporized again. The gas can be exhausted to the outside through an exhaust line of the cryopump. In the semiconductor manufacturing process, a gas having a risk, such as a toxic gas, is often used. When such a hazardous gas remains without being completely exhausted from the cryopump, it is assumed that there is a risk that the hazardous gas is released to the surrounding environment when the cryopump is removed.
It is desirable to provide a cryopump regeneration method that is helpful for safely removing a cryopump, and a cryopump.
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 includes a compressor 12, a cryocooler 14, a cryopump container 16, a cryopanel 18, and a controller 100. Further, the cryopump 10 includes a rough valve 20, a purge valve 22, and a vent valve 24, which are installed in the cryopump container 16.
The compressor 12 is configured to recover a refrigerant gas from the cryocooler 14, pressurize the recovered refrigerant gas, and supply the refrigerant gas to the cryocooler 14 again. The cryocooler 14 is also referred to as an expander or a cold head and configures a cryocooler together with the compressor 12. A thermodynamic cycle that generates cold is configured by performing circulation of a refrigerant gas between the compressor 12 and the cryocooler 14 with an appropriate combination of a pressure fluctuation and a volume fluctuation of the refrigerant gas in the cryocooler 14, and a cooling stage of the cryocooler 14 is cooled to a desired cryogenic temperature. Accordingly, the cryopanel 18 thermally coupled to the cooling stage of the cryocooler 14 can be cooled to a target cooling temperature (for example, in a range of 10 K to 20 K). Although the refrigerant gas is typically a helium gas, any other appropriate gas may be used. In order to facilitate understanding, a direction in which the refrigerant gas flows is indicated with an arrow in
The cryopump container 16 is a vacuum vessel designed to hold vacuum during an evacuation operation of the cryopump 10 and to withstand the pressure of surrounding environment (for example, atmospheric pressure). The cryopump container 16 includes a cryopanel accommodation part 16a having an intake port 17, and a cryocooler accommodation part 16b. The cryopanel accommodation part 16a has a dome shape in which the intake port 17 is open and the opposite side is closed, and the cryopanel 18 is accommodated in the cryopanel accommodation part 16a together with the cooling stage of the cryocooler 14. The cryocooler accommodation part 16b has a cylindrical shape, in which one end thereof is fixed to a room temperature part of the cryocooler 14 and the other end thereof is connected to the cryopanel accommodation part 16a, and the cryocooler 14 is inserted into the cryocooler accommodation part 16b. In this way, the cryocooler 14 is supported by the cryopump container 16. The gas entering from the intake port 17 of the cryopump 10 is captured on the cryopanel 18 by condensation or adsorption. Since the configuration of the cryopump 10, such as the disposition or the shape of the cryopanel 18, can adopt various known configurations as appropriate, the configuration will not be described in detail here.
The vacuum chamber 200 on which the cryopump 10 is mounted is provided with a chamber opening portion 201. The cryopump container 16 is mounted on the vacuum chamber 200 such that the intake port 17 communicates with the chamber opening portion 201. The vacuum chamber 200 may typically include a gate valve 202 that is capable of being opened and closed with respect to the chamber opening portion 201, and the cryopump 10 may be mounted on the vacuum chamber 200 via the gate valve 202.
The gate valve 202 is opened when the vacuum chamber 200 is evacuated by the cryopump 10. Accordingly, the gas from the vacuum chamber 200 can enter the cryopump container 16 through the gate valve 202 and the intake port 17 and reach the cryopanel 18. In addition, the gate valve 202 is closed as necessary, for example, when the maintenance of the vacuum chamber 200 or the cryopump 10 is performed (for example, when the cryopump 10 is regenerated), or the like. In this case, the cryopump 10 is isolated from the vacuum chamber 200, and a gas flow from the vacuum chamber 200 to the cryopump 10 through the intake port 17 is blocked.
The rough valve 20 is configured to exhaust the gas from the cryopump container 16 to a rough pump 30. The rough valve 20 is mounted on the cryopump container 16, for example, the cryocooler accommodation part 16b, and is connected to the rough pump 30 installed outside the cryopump 10. The rough pump 30 is a vacuum pump for evacuating (also referred to as rough pumping) the cryopump 10. When the rough valve 20 is opened by the control of the controller 100, the cryopump container 16 communicates with the rough pump 30, and when the rough valve 20 is closed, the cryopump container 16 is blocked from the rough pump 30. By opening the rough valve 20 and operating the rough pump 30, the gas can be exhausted from the cryopump container 16 and the cryopump 10 can be decompressed. Accordingly, the pressure in the cryopump container 16 can be reduced to the operation start pressure (for example, about 10 Pa) of the cryopump 10.
The purge valve 22 is configured to supply a purge gas to the cryopump container 16. The purge valve 22 is mounted on the cryopump container 16, for example, the cryopanel accommodation part 16a, and is connected to a purge gas source 23 installed outside the cryopump 10. When the purge valve 22 is opened by the control of the controller 100, the purge gas is supplied to the cryopump container 16, and when the purge valve 22 is closed, the supply of the purge gas to the cryopump container 16 is cut off. The purge gas may be, for example, a nitrogen gas, or another dry gas, and the temperature of the purge gas may be adjusted to, for example, room temperature or heated to a temperature higher than room temperature. By opening the purge valve 22 and introducing the purge gas into the cryopump container 16, the cryopump 10 can be pressurized. In addition, the cryopump 10 can be heated from the cryogenic temperature to the temperature of the purge gas.
The vent valve 24 is mounted on the cryopump container 16, for example, the cryocooler accommodation part 16b. The vent valve 24 is provided to exhaust a fluid from the interior of the cryopump 10 to the outside. The vent valve 24 is connected to an exhaust line 32 that guides the exhausted fluid to a storage tank (not shown) outside the cryopump 10. Alternatively, in a case where the exhausted fluid is non-hazardous, the vent valve 24 may be configured to release the exhausted fluid to the surrounding environment. The fluid that is exhausted from the vent valve 24 is basically a gas. However, it may be a liquid or a gas-liquid mixture. The vent valve 24 can be opened and closed by control, and can be mechanically opened by a differential pressure between the inside and the outside of the cryopump container 16. The vent valve 24 is, for example, a normally closed type control valve, and is configured to function as a so-called safety valve.
The cryopump 10 is provided with a temperature sensor 26 that measures the temperature of the cryopanel 18 and outputs a measured temperature signal indicating the measured temperature. The temperature sensor 26 is mounted, for example, on the cooling stage of the cryocooler 14 or on the cryopanel 18. The controller 100 is connected to the temperature sensor 26 to receive the measured temperature signal.
In addition, the cryopump 10 is provided with a pressure sensor 28 that measures the internal pressure of the cryopump container 16 and outputs a measured pressure signal indicating the measured internal pressure. The pressure sensor 28 may be configured to include, in a measurement range, a pressure range from a medium vacuum (for example, an order of 1 Pa (or 10 Pa)) to atmospheric pressure to be able to measure a pressure generated in the cryopump container 16 during the regeneration of the cryopump 10. The pressure sensor 28 is mounted on the cryopump container 16, for example, the cryocooler accommodation part 16b. The controller 100 is connected to the pressure sensor 28 to receive the measured pressure signal.
The pressure sensor 28 is, for example, a thermal conductivity vacuum gauge. The thermal conductivity vacuum gauge includes a Pirani vacuum gauge and a thermocouple vacuum gauge (TC gauge). In the embodiment, the pressure sensor 28 may be a Pirani vacuum gauge. Alternatively, the pressure sensor 28 may be a hot cathode ionization vacuum gauge (for example, a triode type ionization vacuum gauge, a BA vacuum gauge, or the like) or other types of vacuum gauges.
The controller 100 is configured to control the cryopump 10. For example, the controller 100 may control the cryocooler 14, based on the measured temperature of the cryopanel 18 by the temperature sensor 26, in the evacuation operation of the cryopump 10. In addition, in the regeneration operation of the cryopump 10, the controller 100 may control the cryocooler 14, the rough valve 20, the purge valve 22, and the vent valve 24, based on the measured pressure in the cryopump container 16 by the pressure sensor 28 (or, as necessary, based on the measured pressure in the cryopump container 16 and the measured temperature of the cryopanel 18). The controller 100 may be provided integrally with the cryopump 10 or may be configured as a control device separate from the cryopump 10.
An internal configuration of the controller 100 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 100 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 100 to execute regeneration of the cryopump 10.
The evacuation operation of the cryopump 10 is continued, so that a gas from the vacuum chamber 200 is accumulated in the cryopump 10. The regeneration of the cryopump 10 is performed in order to exhaust the gas accommodated in the cryopump 10 to the outside.
The controller 100 may be configured to select and execute any one of at least two types of regeneration sequences set in advance. The controller 100 may select a regeneration sequence to be executed in accordance with an input from a user of the cryopump 10 or in accordance with a command from a host controller (for example, a controller of a vacuum process device).
Normal regeneration is given as a typical regeneration sequence. The normal regeneration is generally to completely exhaust the gas accumulated in the cryopump 10 to the outside, and includes a temperature rising process, an exhaust process, and a cool-down process. In the temperature rising process, the cryopanel 18 is heated from the cryogenic temperature for the evacuation operation to the regeneration temperature, and various gases captured on the cryopanel 18 by condensation or adsorption are re-vaporized. The regeneration temperature is typically, for example, room temperature or a temperature higher than room temperature, and may be selected from, for example, a temperature range of 270 K to 320 K. In the exhaust process, the gas is exhausted from the cryopump container 16 through the rough valve 20 or the vent valve 24. In the exhaust process, the cryopanel 18 is maintained at the regeneration temperature. When the exhaust process is completed, the cool-down process is started. In the cool-down process, the cryopump 10 is re-cooled to the cryogenic temperature for the evacuation operation. When the regeneration is completed in this way, the cryopump 10 can start the evacuation operation again.
As another exemplary regeneration sequence, a “temperature rising regeneration” can be given. Unlike the normal regeneration, in the temperature rising regeneration, re-cooling of the cryopump 10 is not performed. As will be described later with reference to
After the completion of the temperature rising regeneration, the cryopump 10 waits in a state where the temperature has been raised to the temperature rising completion temperature. Therefore, the cryopump 10 after the temperature rising regeneration can be easily removed from the vacuum chamber 200. In other words, the temperature rising regeneration may be executed as preparation for removing the cryopump 10 from the vacuum chamber 200.
First, the temperature rising regeneration is started from the temperature rising process (S10). The controller 100 operates the heat source of the cryopump 10 to raise the temperature of the cryopanel 18 from the cryogenic temperature to the temperature rising completion temperature. The temperature rising completion temperature may be the same as the regeneration temperature in the normal regeneration, and may be selected from, for example, a temperature range of 270 K to 320 K.
The heat source for the temperature rising may be, for example, a purge gas that is supplied from the purge gas source 23 to the cryopump container 16 through the purge valve 22. In addition, the cryopanel 18 may be heated by using a so-called reverse temperature rising of the cryocooler 14. As is known, the reverse temperature rising is a technique of causing adiabatic compression in the refrigerant gas of the cryocooler 14 by operating a drive mechanism of the cryocooler 14 in a direction opposite to that in the cooling operation, and heating the cooling stage and the cryopanel 18 with the compression heat obtained as a result. Alternatively, for example, in a case where a heating device such as an electric heater is installed at the cryopanel 18, the cooling stage of the cryocooler 14, or another location of the cryopump 10, the cryopanel 18 may be heated by using the heating device. In this way, the gas captured on the cryopanel 18 is vaporized again. The gas released from the cryopanel 18 to the cryopump container 16 in this way may be exhausted to the outside of the cryopump 10 together with the purge gas from the cryopump container 16 through the vent valve 24 and the exhaust line 32.
Alternatively, the temperature rising process (S10) may include the rough pumping of the cryopump container 16 when the temperature of the cryopanel 18 is raised to an intermediate target temperature between the cryogenic temperature and the temperature rising completion temperature. During the rough pumping, the supply of the purge gas may be stopped, and the purge gas may be supplied again after the rough pumping. In this way, the gas re-vaporized from the cryopanel 18 may be exhausted together with the purge gas to the outside of the cryopump 10 from the cryopump container 16 through the rough valve 20 and the rough pump 30.
The intermediate target temperature may be selected from a temperature for
vaporizing a specific gas, for example, hydrogen condensed or adsorbed on the cryopanel 18, for example, a temperature range of 30 K to 50 K. Alternatively, the intermediate target temperature may be set to another temperature in order to vaporize another gas. In this way, the specific gas can be exhausted from the cryopump 10 in the initial stage or the middle of the temperature rising process. In particular, by early exhausting a flammable gas such as hydrogen from the cryopump 10, it is possible to reduce or minimize the risk of unanticipated combustion or explosion of such a flammable gas in the cryopump 10.
During the temperature rising, the temperature of the cryopanel 18 is periodically measured by the temperature sensor 26, and the measured temperature signal of the temperature sensor 26 is provided to the controller 100. The controller 100 compares the measured temperature of the cryopanel 18 with the temperature rising completion temperature (S12). In a case where the measured temperature is lower than the temperature rising completion temperature (No in S12), the controller 100 compares the temperature of the cryopanel 18 that is measured subsequently with the temperature rising completion temperature again (S12). In this way, the temperature rising process (S10) is continued until the temperature of the cryopanel 18 reaches the temperature rising completion temperature.
On the other hand, in a case where the measured temperature reaches or exceeds the temperature rising completion temperature (Yes in S12), the controller 100 ends the temperature rising process (S10) and executes processing of determining whether or not to complete the temperature rising regeneration (S14). The exemplary completion determination processing will be described later with reference to
When the temperature rising regeneration is completed, that is, when in the completion determination processing (S14) of the temperature rising regeneration, it is determined that the temperature rising regeneration is completed, the purge gas is supplied to the cryopump container 16 through the purge valve 22 (S16). This is performed to break the vacuum of the cryopump container 16 and return the internal pressure to the ambient pressure (for example, atmospheric pressure).
In addition, in a case where the reverse temperature rising of the cryocooler 14 is continued even during the completion determination processing (S14), the cryocooler 14 is stopped (S18). The motor that drives the cryocooler 14 is de-energized, and the operation of the cryocooler 14 is stopped. The cryocooler 14 may be stopped when the temperature rising process (S10) is ended, or at any desired timing after the temperature rising process is ended, as necessary.
In this way, the temperature rising regeneration of the cryopump 10 is completed. After the temperature rising regeneration is completed, the cryopump 10 may be removed from the vacuum chamber 200 (S20).
Thereafter, maintenance may be performed on the cryopump 10 and the cryopump 10 may be mounted on the vacuum chamber 200 again. Alternatively, another cryopump 10 (for example, a new cryopump) may be prepared for replacement, and the cryopump may be mounted on the vacuum chamber 200. The cryopump 10 can start the evacuation operation again.
In the semiconductor manufacturing process in which the cryopump 10 is used, for example, a toxic gas such as a fluorine-based gas such as BF3 or a halogen-based gas is often used. By the temperature rising regeneration, such a toxic gas has to be ideally completely exhausted from the cryopump 10, similar to other gases. However, when a part of the toxic gas remains in the cryopump 10 without being completely exhausted from the cryopump 10, the remaining toxic gas may leak from the cryopump 10 to the surrounding environment when the cryopump 10 is removed from the vacuum chamber 200.
Therefore, a technique is desired that can confirm the presence of the remaining gas when the temperature rising regeneration is completed. In this embodiment, the fact that the relative sensitivity of the pressure sensor 28 may depend on the type of gas is utilized.
In general, the vacuum gauge is calibrated with a reference gas having a specific composition (for example, a nitrogen gas, air, or the like). That is, a reading value of the pressure indicated by the vacuum gauge in the gas atmosphere having a composition different from that of the reference gas may vary depending on the composition.
Various gases are captured on the cryopump 10 according to the type of a gas that is used in the vacuum chamber 200. Therefore, during the regeneration of the cryopump 10, the gas can be re-vaporized, the purge gas can be supplied, and the mixed gas can be exhausted, so that the gas composition in the cryopump container 16 can be changed in various ways from moment to moment. The pressure value measured by the pressure sensor 28 is affected by the actual pressure change and the change in composition. In the initial stage of the temperature rising regeneration, various gases captured on the cryopanel 18 are re-vaporized, so that the gas composition in the cryopump container 16 is unknown and can be changed in various ways. However, the proportion of the purge gas in the gas composition gradually increases as the exhaust of the various gases progresses, and finally, the cryopump container 16 is substantially occupied only by the purge gas. That is, the gas composition in the cryopump container 16 is known, and the influence of the change in the gas composition on the measured pressure value is suppressed.
Based on such individual considerations by the inventors of the present invention, in this embodiment, a timing when the temperature rising regeneration of the cryopump 10 is completed is determined based on a history of a pressure rise rate of the cryopump container 16. As described above, in the initial stage of the temperature rising regeneration, the measured pressure of the pressure sensor 28 is affected by a change in gas composition, and a fluctuation of the pressure rise rate becomes relatively large. On the other hand, in the completion stage of the temperature rising regeneration, it is expected that the fluctuation of the pressure rise rate becomes small because the gas composition becomes constant. Therefore, the timing when the temperature rising regeneration is completed can be appropriately determined based on the history of the pressure rise rate.
The completion of the temperature rising regeneration may include acquiring the history of the pressure rise rate in the cryopump container 16 by repeating supply of a purge gas to the cryopump container 16, rough pumping of the cryopump container 16, and measurement of the pressure rise rate, and determining whether or not to complete the regeneration of the cryopump 10, based on the acquired history of the pressure rise rate. In this way, the cycle including purging, rough pumping, and pressure rise rate measurement is repeated, so that the pressure rise rate can be measured under the same or similar conditions each time and the history of the pressure rise rate can be more accurately acquired. When it is evaluated that a fluctuation of the pressure rise rate identified from the acquired history of the pressure rise rate is sufficiently small, it can be determined that the gas captured on the cryopanel 18 is sufficiently exhausted from the cryopump 10. In this way, the timing when the temperature rising regeneration is completed can be determined.
The determination of the completion of the temperature rising regeneration according to the embodiment may be particularly effective in order to determine whether or not a toxic gas such as BF3 remains in the cryopump 10. This is because the toxic gas often has a relative sensitivity significantly different from that of the reference gas (for example, a nitrogen gas) used to calibrate the pressure sensor 28, and thus, when the toxic gas remains in the cryopump 10 in large amounts, the tendency is that the fluctuation of the pressure rise rate increases.
In this exemplary completion determination processing, the controller 100 is configured to determine whether or not to complete the regeneration of the cryopump, based on the history of the pressure rise rate in the cryopump container 16. In order to acquire the history of the pressure rise rate, the controller 100 is configured to operate the purge valve 22, the rough valve 20, and the pressure sensor 28 to repeat the supply of the purge gas to the cryopump container 16, the rough pumping of the cryopump container 16, and the measurement of the pressure rise rate in the cryopump container 16, in a state where the temperature of the cryopanel 18 is raised to the temperature rising completion temperature. During the execution of the completion determination processing, the pressure in the cryopump container 16 is periodically measured by the pressure sensor 28, and the measured pressure signal of the pressure sensor 28 is provided to the controller 100. The controller 100 is configured to acquire the amount of change in the pressure rise rate every time the pressure rise rate is measured, and to complete the regeneration of the cryopump 10 when the number of times that the acquired amount of change in the pressure rise rate is consecutively within the allowable range reaches a predetermined number of times (for example, at least two times).
As shown in
The rough pumping of the cryopump container 16 may be ended when the cryopump container 16 is decompressed to a predetermined rough pumping end pressure. The rough pumping end pressure may be selected from, for example, a pressure range of 100 Pa or more and less than 1000 Pa. In this pressure range, since a difference in the relative sensitivity of the pressure sensor 28 (for example, a Pirani vacuum gauge) depending on the type of gas becomes large, this pressure range is suitable for the present method. The controller 100 may compare the measured pressure in the cryopump container 16 with the rough pumping end pressure, continue the rough pumping of the cryopump container 16 (that is, open the rough valve 20) in a case where the measured pressure exceeds the rough pumping end pressure, and end the rough pumping of the cryopump container 16 (that is, close the rough valve 20) in a case where the measured pressure reaches or falls below the rough pumping end pressure.
Alternatively, the rough pumping of the cryopump container 16 may be ended based on the pressure drop rate (pressure drop amount per unit time) of the cryopump container 16. In general, the higher the pressure in the cryopump container 16, the larger the pressure drop rate, and the pressure drop rate decreases as the cryopump container 16 is decompressed. Therefore, the rough pumping may be ended in accordance with a sufficient decrease in the pressure drop rate. The controller 100 may acquire the pressure drop rate from the measured pressure in the cryopump container 16. The controller 100 may compare the acquired pressure drop rate with a pressure drop rate threshold, continue the rough pumping of the cryopump container 16 in a case where the pressure drop rate exceeds the pressure drop rate threshold, and end the rough pumping of the cryopump container 16 in a case where the pressure drop rate falls below the pressure drop rate threshold.
Alternatively, the rough pumping of the cryopump container 16 may be ended when a predetermined rough pumping time has elapsed from the start of the rough pumping. The controller 100 may compare the elapsed time from the start of the rough pumping with the rough pumping time, continue the rough pumping of the cryopump container 16 until the elapsed time reaches the rough pumping time, and end the rough pumping of the cryopump container 16 when the elapsed time reaches the rough pumping time. The controller 100 may compare the pressure in the cryopump container 16 measured at the point in time of the rough pumping end with the rough pumping end pressure, supply a purge gas to the cryopump container 16 in a case where the measured pressure does not reach the rough pumping end pressure, and then perform the rough pumping once again.
When the rough pumping of the cryopump container 16 is ended, the pressure rise rate in the cryopump container 16 is measured, and the amount of change in the pressure rise rate is acquired (S32). The pressure rise rate in the cryopump container 16 is measured by the pressure sensor 28 in a state where each valve provided in the cryopump container 16 is closed to isolate the internal pressure of the cryopump container 16 from the surrounding environment. A pressure is measured over a predetermined measurement time, and a pressure rise rate can be obtained by dividing a pressure increment between the measurement start time and the measurement end time by the measurement time. The amount of change in the pressure rise rate may be defined as the amount of change (for example, a difference or a ratio) in the pressure rise rate measured in the current measurement cycle with respect to the pressure rise rate measured in the previous measurement cycle (that is, the cycle including purge, rough pumping, and pressure rise rate measurement). The controller 100 may be configured to calculate the amount of change from the pressure rise rates in the previous and current times.
In the first measurement cycle that is performed at the time of the start of the completion determination processing, the previous pressure rise rate for calculating the amount of change does not exist yet. Therefore, in the first measurement cycle, after the pressure rise rate in the cryopump container 16 is measured, the process proceeds to the second measurement cycle (that is, the purge gas is supplied to the cryopump container 16, the cryopump container 16 is roughly pumped (S30), and the pressure rise rate in the cryopump container 16 is measured to acquire the amount of change in the pressure rise rate (S32)).
Subsequently, the acquired amount of change in the pressure rise rate is evaluated (S34). This is a first test on the amount of change in the pressure rise rate. The controller 100 compares the acquired amount of change in the pressure rise rate with an allowable range, determines that the test is passed, in a case where the amount of change in the pressure rise rate is within the allowable range, and determines that the test is failed, in a case where the amount of change in the pressure rise rate is outside the allowable range.
The allowable range may be set as a ratio, and may be, for example, within ±30%, within ≡20%, or within ±10%. Alternatively, the allowable range may be set as a value of the pressure rise rate, and may be, for example, within ±30 Pa/min, within ±20 Pa/min, or within ±10 Pa/min. The setting of this allowable range may be looser than a determination criterion (for example, within 5 Pa/min) of the pressure rise rate that is performed before the start of the cool-down in the normal regeneration (in the temperature rising regeneration, the remaining moisture in the cryopump container 16 is allowed, whereas the moisture has to be exhausted as much as possible in the normal regeneration). The controller 100 may determine that the test is passed, in a case where the amount of change in the pressure rise rate falls within the allowable range in both the ratio and the absolute value, or may determine that the test is passed, in a case where the amount of change in the pressure rise rate falls within the allowable range in any one of the ratio and the absolute value. Such an allowable range may be appropriately set based on the empirical knowledge of the designer of the cryopump 10 or the experiment or simulation by the designer, and may be stored in advance in the controller 100.
Next, the measurement cycle is performed once again. That is, the purge gas is supplied to the cryopump container 16 (S36), the cryopump container 16 is roughly pumped (S38), the pressure rise rate in the cryopump container 16 is measured, and the amount of change in the pressure rise rate is acquired (S40).
Then, the acquired amount of change in the pressure rise rate is evaluated (S42). This is a second test on the amount of change in the pressure rise rate. As in the first test, the controller 100 compares the acquired amount of change in the pressure rise rate with the allowable range, determines that the test is passed, in a case where the amount of change in the pressure rise rate falls within the allowable range, and determines that the test is failed, in a case where the amount of change in the pressure rise rate falls outside the allowable range.
Subsequently, it is determined whether or not the number of times that the acquired amount of change in the pressure rise rate is consecutively within the allowable range reaches a predetermined number of times (in this example, two times) (S44). In a case where the test result is a failure in any of the first test and the second test (No in S44), the measurement cycle is further repeated. That is, the purge gas is supplied to the cryopump container 16 (S46), the cryopump container 16 is roughly pumped (S38), the pressure rise rate in the cryopump container 16 is measured, and the amount of change in the pressure rise rate is acquired (S40).
On the other hand, in a case where the test result is passed in both the first test and the second test (Yes in S44), it can be considered that the pressure rise rate of the cryopump container 16 is stable for a certain period. This is because, as described above, the fact that the gas composition in the cryopump container 16 is substantially composed of the purge gas can be meant, and thus, the temperature rising regeneration of the cryopump 10 can be completed (S48). In this case, as described with reference to
According to the embodiment, by repeating the cycle including purging, rough pumping, and measurement of the pressure rise rate, the inside of the cryopump container 16 is cleaned, and thus, it is possible to appropriately determine a timing when the temperature rising regeneration of the cryopump 10 is completed, based on the acquired history of the pressure rise rate of the cryopump container 16. It is possible to reduce or minimize the risk of a toxic gas leakage that may occur when the cryopump 10 is removed from the vacuum chamber 200, and to improve the safety of the work of removing the cryopump 10.
In a case of being necessary, the temperature rising regeneration of the cryopump 10 may be completed in a case where the acquired amount of change in the pressure rise rate consecutively passes the test more times (for example, three times or more). In this way, it is possible to more reliably determine that the pressure rise rate is stable.
The present invention has been described above based on the embodiment. 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 a cryopump regeneration method and a 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 |
|---|---|---|---|
| 2022-040910 | Mar 2022 | JP | national |
This is a bypass continuation of International PCT Application No. PCT/JP2023/002220, filed on Jan. 25, 2023, which claims priority to Japanese Patent Application No. 2022-040910, filed on Mar. 16, 2022, which are incorporated by reference herein in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2023/002220 | Jan 2023 | WO |
| Child | 18884218 | US |
