TW202338211A - Cryopump regeneration method and cryopump - Google Patents

Abstract

Provided is a regeneration method for a cryopump (10). The cryopump (10) comprises a cryopanel (18) and a cryopump container (16) accommodating the cryopanel (18). The method comprises raising the temperature of the cryopanel (18) from an extremely low temperature to a heating completion temperature, and completing regeneration of the cryopump (10) in a state in which the temperature of the cryopanel (18) has been raised to the heating completion temperature. Said completion comprises: repeatedly supplying a purge gas to the cryopump container (16), carrying out a rough evacuation of the cryopump container (16), and measuring the pressure increase rate inside the cryopump container (16) to obtain a history of the pressure increase rate; and determining whether to terminate the regeneration of the cryopump (10) on the basis of the obtained history of the pressure increase rate.

Description

Regeneration method of cryopump and cryopump

The invention relates to a cryogenic pump regeneration method and a cryogenic pump.

A cryopump is a vacuum pump that collects gas molecules on a cryogenic plate that is cooled to extremely low temperatures through condensation or adsorption and discharges them. Cryogenic pumps are generally used to achieve clean vacuum environments required in semiconductor circuit manufacturing processes and the like. Since the cryopump is a so-called gas accumulation vacuum pump, it needs to be regenerated by regularly discharging the captured gas to the outside. [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Publication No. 10-512645

[Problem to be solved by the invention]

For replacement or maintenance, the cryopump may be removed from the vacuum process device. In preparation for the unloading operation, the cryopump is warmed up to a suitable temperature (eg, room temperature). The gas captured in the cryopump is vaporized again. The gas can be discharged to the outside through the discharge line of the cryopump. Hazardous gases such as toxic gases are often used in semiconductor manufacturing processes. If this hazardous gas is not completely exhausted from the cryopump and remains, there should be a risk that the hazardous gas may be released into the surrounding environment when the cryopump is removed.

One of the exemplary objects of one aspect of the present invention is to provide a cryopump regeneration method and a cryopump that facilitate safe removal of the cryopump. [Technical means to solve problems]

According to an aspect of the present invention, a method for regenerating a cryopump is provided. The cryopump has a cryogenic plate and a cryogenic pump container for storing the cryogenic plate. The method includes: the steps of raising the temperature of the cryogenic plate from extremely low temperature to the temperature raising completion temperature; and the step of completing the regeneration of the cryopump while the cryogenic plate is warming up to the temperature raising completion temperature. The steps to be completed include: repeating the steps of supplying purge gas to the cryopump container, roughly pumping the cryopump container, and then measuring the pressure rise rate in the cryopump container to obtain the pressure rise rate; and based on the obtained pressure rise rate. process to determine whether to complete the regeneration step of the cryopump.

According to one aspect of the present invention, a cryopump includes: a cryopanel; a cryopump container that accommodates the cryopanel; a heat source that heats the cryopanel; a flush valve that supplies purge gas to the cryopump container; and discharges the gas from the cryopump container to rough pumping. a rough pump valve of the pump; a pressure sensor for measuring the pressure in the cryopump container; and a controller configured to operate the heat source in such a manner that the cryopanel heats up from a very low temperature to a temperature at which the temperature rise is completed, and when the cryopanel is heated up to the temperature at which the temperature rise is completed, The regeneration of the cryopump is completed under the condition of high temperature. The controller is configured to operate the flush valve, the rough pumping valve, and the pressure sensor to repeatedly supply the purge gas to the cryopump container, then roughly pump the cryopump container, and then measure the pressure rise rate in the cryopump container to obtain the pressure rise. The process of the pressure rise rate is used to determine whether to complete the regeneration of the cryogenic pump. [Effects of the invention]

According to the present invention, it is possible to provide a cryopump regeneration method and a cryopump that facilitate safe removal of the cryopump.

Hereinafter, the mode for implementing the present invention will be described in detail with reference to the drawings. In the description and drawings, the same or equivalent components, members, and processes are denoted by the same symbols, and repeated descriptions are appropriately omitted. The scale and shape of each part in the illustrations are simply set for convenience of explanation and will not be interpreted restrictively unless otherwise stated. The embodiments are examples and do not limit the scope of the present invention in any way. All features described in the embodiments and their combinations are not necessarily essential to the invention.

FIG. 1 schematically shows a cryopump 10 according to the embodiment. The cryopump 10 is installed in a vacuum chamber 200 of, for example, an ion implantation device, a sputtering device, an evaporation device or other vacuum process devices, and is used to increase the vacuum degree in the vacuum chamber 200 to the level required for the desired vacuum process. level. For example, a high vacuum degree of approximately 10 ^-5 Pa to 10 ^-8 Pa is achieved in the vacuum chamber 200 .

The cryopump 10 includes a compressor 12, a refrigerator 14, a cryopump container 16, a cryopanel 18, and a controller 100. Furthermore, the cryopump 10 includes a roughing valve 20 , a flush valve 22 , and an exhaust valve 24 , which are provided in the cryopump container 16 .

The compressor 12 collects refrigerant gas from the refrigerator 14 , increases the pressure of the collected refrigerant gas, and supplies the refrigerant gas to the refrigerator 14 again. The refrigerator 14 is also called an expander or a cold head, and together with the compressor 12 constitutes a very low temperature refrigerator. The circulation of the refrigerant gas between the compressor 12 and the refrigerator 14 is performed by a combination of appropriate pressure changes and volume changes of the refrigerant gas in the refrigerator 14, thereby forming a thermodynamic cycle of refrigeration, so that the refrigerator The cooling stage of 14 is cooled to the desired extremely low temperature. Thereby, the cryopanel 18 thermally coupled with the cooling stage of the refrigerator 14 can be cooled to the target cooling temperature (for example, 10K to 20K). The refrigerant gas is usually helium, but other suitable gases may also be used. For ease of understanding, arrows are used in Figure 1 to indicate the direction of refrigerant gas flow. As an example, the ultra-low temperature freezer is a two-stage Gifford-McMahon (GM) freezer, but it can also be a pulse tube freezer, a Stirling freezer or other types of ultra-low temperature freezers. .

The cryopump container 16 is designed to maintain a vacuum during the vacuum exhaust operation of the cryopump 10 and can withstand the pressure of the surrounding environment (eg, atmospheric pressure). The cryopump container 16 includes a cryopanel storage portion 16a having an air suction port 17 and a refrigerator storage portion 16b. The cryopanel accommodating part 16a has a dome-like shape in which the suction port 17 is open and the opposite side is closed, and the cryopanel 18 is accommodated in the inside together with the cooling stage of the refrigerator 14. The refrigerator storage part 16b has a cylindrical shape, one end of which is fixed to the room temperature part of the refrigerator 14, the other end is connected to the cryopanel storage part 16a, and the refrigerator 14 is inserted into the inside. In this way, the refrigerator 14 is supported by the cryopump container 16 . The gas entering from the suction port 17 of the cryopump 10 is collected into the cryopanel 18 through condensation or adsorption. The structure of the cryopump 10 such as the arrangement and shape of the cryopanel 18 can be suitably adopted from various known structures, and therefore will not be described in detail here.

A chamber opening 201 is provided in the vacuum chamber 200 in which the cryopump 10 is installed. The cryopump container 16 is installed in the vacuum chamber 200 so that the suction port 17 communicates with the chamber opening 201 . The vacuum chamber 200 may generally be provided with a gate valve 202 capable of opening and closing the chamber opening 201 , and the cryopump 10 may be installed in 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 . Therefore, the gas from the vacuum chamber 200 can enter the cryopump container 16 through the gate valve 202 and the suction port 17 and reach the cryopanel 18 . In addition, the gate valve 202 is closed as necessary when performing maintenance on the vacuum chamber 200 or the cryopump 10 (for example, regeneration of the cryopump 10). At this time, the cryopump 10 is isolated from the vacuum chamber 200 , and the inflow of gas from the vacuum chamber 200 to the cryopump 10 through the suction port 17 is blocked.

The rough valve 20 is configured to discharge gas from the cryopump container 16 to the rough pump 30 . The rough valve 20 is attached to the cryopump container 16 , for example, the refrigerator housing 16 b, and is connected to the rough pump 30 provided outside the cryopump 10 . The roughing pump 30 is a vacuum pump used to evacuate the cryopump 10 (also called roughing). When the roughing valve 20 is opened under the control of the controller 100, the cryopump container 16 and the roughing pump 30 are connected. When the roughing valve 20 is closed, the cryopump container 16 and the roughing pump 30 are blocked. By opening the roughing valve 20 and operating the roughing pump 30 , the gas can be discharged from the cryopump container 16 and the pressure of the cryopump 10 can be reduced. Thereby, the pressure in the cryopump container 16 can be reduced to the operation start pressure of the cryopump 10 (for example, about 10 Pa).

The flush valve 22 is configured to supply purge gas to the cryopump container 16 . The flush valve 22 is attached to the cryopump container 16 , for example, the cryopanel housing 16 a , and is connected to a purge gas source 23 provided outside the cryopump 10 . When the flush valve 22 is opened under the control of the controller 100, the purge gas is supplied to the cryopump container 16. When the flush valve 22 is closed, the supply of purge gas to the cryopump container 16 is blocked. The purge gas may be, for example, nitrogen or other dry gases, and the temperature of the purge gas may be adjusted to room temperature, for example, or may be heated to a temperature higher than room temperature. By opening the flush valve 22 and introducing the purge gas into the cryopump container 16, the pressure of the cryopump 10 can be increased. Furthermore, the cryopump 10 can be heated from a very low temperature to the temperature of the purge gas.

The exhaust valve 24 is installed in the cryopump container 16, for example, the refrigerator storage part 16b. The exhaust valve 24 is provided to discharge fluid from the inside of the cryopump 10 to the outside. The exhaust valve 24 is connected to a discharge line 32 that introduces discharged fluid into a storage tank (not shown) outside the cryopump 10 . Alternatively, the exhaust valve 24 may be configured to release the exhausted fluid to the surrounding environment where the exhausted fluid is not harmful. The fluid discharged from the exhaust valve 24 is basically a gas, but may also be a liquid or a gas-liquid mixture. The exhaust valve 24 can be opened and closed by control, and can be opened mechanically by the pressure difference between the inside and outside of the cryopump container 16 . The exhaust valve 24 is, for example, a normally closed control valve, and is configured to also 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, for example, installed on the cooling stage or the cryogenic plate 18 of the refrigerator 14 . The controller 100 is connected to the temperature sensor 26 to receive the measured temperature signal.

Furthermore, 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 measure a pressure range from a moderate vacuum (eg, 1 Pa (or 10 Pa) level) to atmospheric pressure to be able to measure the pressure generated within the cryopump container 16 during regeneration of the cryopump 10 . The pressure sensor 28 is installed in the cryopump container 16, such as the refrigerator housing 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 conduction vacuum gauge. Thermal conduction vacuum gauges include Pirani vacuum gauges and thermocouple gauges (TC gauges). In this embodiment, the pressure sensor 28 may be a Pirani vacuum gauge. Alternatively, pressure sensor 28 may be a hot cathode ionization vacuum gauge (eg, triode gauge, BA gauge, etc.) or other type of vacuum gauge.

The controller 100 is configured to control the cryopump 10 . For example, during the vacuum exhaust operation of the cryopump 10 , the controller 100 may control the refrigerator 14 based on the measured temperature of the cryopanel 18 based on the temperature sensor 26 . In addition, during the regeneration operation of the cryopump 10, the controller 100 may rely on the measured pressure in the cryopump container 16 based on the pressure sensor 28 (or, if necessary, based on the measured pressure in the cryopump container 16 and the temperature of the cryopanel 18 (measuring temperature) to control the refrigerator 14, the roughing valve 20, the flushing valve 22, and the roughing pump 24. The controller 100 may be integrally provided with the cryopump 10 , or may be configured as a separate control device from the cryopump 10 .

As for the internal structure of the controller 100, as a hardware structure, it can be realized by components or circuits represented by a computer's CPU or memory, and as a software structure, it can be realized by a computer program, etc., but in the figure it is appropriate to The ground is drawn into functional blocks realized by the cooperation of the two. Those skilled in the art can certainly understand that these functional blocks are implemented in various forms through a combination of hardware and software.

For example, the controller 100 can use a CPU (Central Processing Unit: Achieved by a combination of a central processing unit (CPU), 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 100 to perform regeneration of the cryopump 10 .

As the vacuum exhaust operation of the cryopump 10 continues, gas from the vacuum chamber 200 accumulates in the cryopump 10 . In order to discharge the gas accumulated in the cryopump 10 to the outside, the cryopump 10 is regenerated.

The controller 100 may be configured to select and execute any one of at least two preset regeneration programs. The controller 100 may select a regeneration program to be executed based on input from a user of the cryopump 10 or based on instructions from a higher-level controller (eg, a controller of a vacuum programming device).

A typical regeneration procedure is normal regeneration. Normally, regeneration generally involves completely discharging the gas accumulated in the cryopump 10 to the outside, and includes a temperature rising process, a discharging process, and a cooling process. In the temperature raising step, the cryopanel 18 is heated from a very low temperature for vacuum exhaust operation to a regeneration temperature, and various gases trapped in the cryopanel 18 by condensation or adsorption are vaporized again. The regeneration temperature is typically room temperature or a temperature higher than room temperature, and can be selected from a temperature range of 270K to 320K, for example. In the discharge process, the gas is discharged from the cryopump container 16 through the rough valve 20 or the exhaust valve 24 . During the discharge process, the cryopanel 18 is maintained at the regeneration temperature. After the discharge process is completed, the cooling process is started. In the cooling process, the cryopump 10 is cooled again to an extremely low temperature for vacuum exhaust operation. When regeneration is completed in this way, the cryopump 10 can start the vacuum exhaust operation again.

As another exemplary regeneration procedure, "heating regeneration" can be cited. Unlike normal regeneration, during temperature-increasing regeneration, the cryopump 10 is not re-cooled. As will be described later with reference to FIG. 2 , the temperature rise regeneration includes: the step of raising the temperature of the cryopanel 18 from a very low temperature to the temperature rise completion temperature; and the step of completing the regeneration of the cryopump 10 in a state where the cryopanel 18 is heated to the temperature rise completion temperature. Therefore, the controller 100 may be configured to operate the heat source of the cryopump 10 so as to raise the temperature of the cryopanel 18 from the extremely low temperature to the temperature rise completion temperature, and complete the regeneration of the cryopump 10 in a state where the cryopanel 18 is heated to the temperature rise completion temperature.

After the temperature rise regeneration is completed, the cryopump 10 waits while the temperature rises to the temperature rise completion temperature. Therefore, the cryopump 10 after temperature increase and regeneration can be easily detached from the vacuum chamber 200 . In other words, the temperature rise regeneration may be performed as preparation for detaching the cryopump 10 from the vacuum chamber 200 .

FIG. 2 is a flowchart showing temperature-raising regeneration of the cryopump 10 according to the embodiment. The temperature-increasing regeneration is performed in a state where the cryopump 10 is installed in the vacuum chamber 200 to be evacuated by the cryopump 10 . Temperature rise regeneration is usually performed after the vacuum exhaust operation of the cryopump 10 is completed. When the temperature rise regeneration is started, the cryopanel 18 is cooled to an extremely low temperature (for example, 10K to 20K) for vacuum exhaust operation.

Temperature-raising regeneration first starts with the temperature-raising process (S10). The controller 100 operates the heat source of the cryopump 10 so as to raise the temperature of the cryopanel 18 from a very low temperature to a temperature that has been completed. The temperature rise completion temperature may be the same as the regeneration temperature during normal regeneration, and may be selected from a temperature range of 270K to 320K, for example.

The heat source used to raise the temperature may be, for example, the purge gas supplied from the purge gas source 23 to the cryopump container 16 through the flush valve 22 . Alternatively, the cryopanel 18 may be heated using so-called reverse temperature rise of the refrigerator 14 . As is well known, reverse temperature rise refers to adiabatic compression of the refrigerant gas in the refrigerator 14 by operating the drive mechanism of the refrigerator 14 in the opposite direction to the cooling operation, and the resulting compression heat is used to heat the cooling stage and the cryopanel 18 technology. Alternatively, when a heating device such as an electric heater is installed on the cryopanel 18, the cooling stage of the freezer 14, or other parts of the cryopump 10, the cryopanel 18 can be heated. In this way, the gas collected in the cryopanel 18 is vaporized again. In this way, the gas released from the cryopanel 18 to the cryopump container 16 can be discharged from the cryopump container 16 through the exhaust valve 24 and the discharge pipe 32 to the outside of the cryopump 10 together with the purge gas.

Alternatively, the temperature increasing process (S10) may include a step of rough pumping the cryopump container 16 when the cryopanel 18 is heated to an intermediate target temperature between the extremely low temperature and the temperature increasing completion temperature. During rough pumping, the supply of purge gas can be stopped and the purge gas can be supplied again after rough pumping. In this way, the gas regasified from the cryopanel 18 can be discharged from the cryopump container 16 to the outside of the cryopump 10 through the roughing valve 20 and the roughing pump 30 together with the purge gas.

The intermediate target temperature can be selected from a temperature at which a specific gas, such as hydrogen, condensed or adsorbed on the cryopanel 18 is vaporized, for example, from a temperature range of 30K to 50K. Alternatively, the intermediate target temperature can be set to other temperatures used to vaporize other gases. Thereby, the specific gas can be discharged from the cryopump 10 in the initial stage or in the middle of the temperature raising process. In particular, flammable gases such as hydrogen are discharged from the cryopump 10 early, thereby reducing or minimizing the risk of accidental combustion or explosion of such flammable gas in the cryopump 10 .

During the heating period, the temperature sensor 26 periodically measures the temperature of the cryopanel 18 and provides the measured temperature signal from the temperature sensor 26 to the controller 100 . The controller 100 compares the measured temperature of the cryopanel 18 with the temperature increase completion temperature (S12). When the measured temperature is lower than the temperature rise completion temperature (No in S12), the controller 100 compares the subsequently measured temperature of the cryopanel 18 with the temperature rise completion temperature again (S12). In this way, the temperature raising process (S10) continues until the temperature of the cryopanel 18 reaches the temperature raising completion temperature.

On the other hand, when the measured temperature reaches or exceeds the temperature rise completion temperature (YES in S12), the controller 100 ends the temperature rise process (S10) and executes a process of determining whether the temperature rise regeneration is completed (S14). An exemplary completion determination process will be described later with reference to FIG. 3 . This completion determination process may be performed immediately when the measured temperature reaches the temperature rise completion temperature, or may be performed after a predetermined time has elapsed. When waiting for a predetermined time before completing the determination process, the purge gas can be continued to be supplied to the cryopump container 16 during the predetermined time (this is sometimes called extended purge).

When the temperature rise regeneration is completed, that is, when it is determined in the temperature rise regeneration completion determination process (S14) that the temperature rise regeneration is completed, the purge gas is supplied to the cryopump container 16 through the flush valve 22 (S16). This is done to break the vacuum of the cryopump container 16 and return the internal pressure to ambient pressure (eg, atmospheric pressure).

Moreover, when the reverse rotation temperature increase of the refrigerator 14 continues in the completion determination process (S14), the refrigerator 14 is stopped (S18). The power supply to the motor driving the refrigerator 14 is stopped, and the operation of the refrigerator 14 is stopped. In addition, if necessary, the refrigerator 14 can be stopped when the temperature rising step (S10) is completed, or at any time after the temperature rising step is completed.

Thus, the temperature rise and regeneration of the cryopump 10 is completed. After the temperature rise regeneration is completed, the cryopump 10 can be detached from the vacuum chamber 200 (S20).

The cryopump 10 can then be repaired and reinstalled in the vacuum chamber 200 . Alternatively, another cryopump 10 (eg, a new cryopump) may be prepared for replacement and installed in the vacuum chamber 200 . The cryopump 10 can restart the vacuum exhaust operation.

However, in the semiconductor manufacturing process using the cryopump 10 , toxic gases such as fluorine-based gases such as BF ₃ or halogen-based gases are often used. Through temperature-raising regeneration, these toxic gases, like other gases, should ideally be completely discharged from the cryopump 10 . However, if part of the toxic gas is not completely discharged from the cryopump 10 and remains, the remaining toxic gas may leak from the cryopump 10 into the surrounding environment when the cryopump 10 is removed from the vacuum chamber 200 .

Therefore, there is a need for a technology that can confirm the presence of residual gas when the temperature rise regeneration is completed. In this embodiment, the phenomenon that the relative sensitivity of the pressure sensor 28 depends on the gas type is utilized.

Generally, vacuum gauges are calibrated using a reference gas with a specific composition (for example, nitrogen or air, etc.). That is, in an atmosphere with a different composition than the reference gas, the reading value of the pressure displayed by the vacuum gauge may differ depending on the composition.

The cryopump 10 captures various gases according to the type of gas used in the vacuum chamber 200 . Therefore, during the regeneration of the cryopump 10, the gas composition in the cryopump container 16 may change at any time due to regasification of such gas, supply of purge gas, discharge of the mixed gas, etc. The pressure value measured by the pressure sensor 28 is also affected by this composition change in addition to the actual pressure change. In the early stage of temperature rise regeneration, due to the regasification of various gases captured in the cryopanel 18, the gas composition in the cryopump container 16 is unknown and may undergo various changes. In contrast, as these various gases are discharged As the process progresses, the proportion of purified gas in the gas composition gradually increases, and finally the cryopump container 16 essentially only contains purified gas. That is, the gas composition in the cryopump container 16 becomes known, and the influence of changes in the gas composition on the measured pressure value can be suppressed.

Based on this unique consideration of the present inventor, in this embodiment, the timing to complete the temperature rise regeneration of the cryopump 10 is determined based on the history of the pressure rise rate of the cryopump container 16 . In the initial stage of temperature-raising regeneration, as mentioned above, the pressure measured by the pressure sensor 28 is affected by changes in the gas composition, and the pressure rise rate fluctuates relatively greatly. On the other hand, in the completion stage of temperature-raising regeneration, it is expected that the pressure measured by the pressure sensor 28 will vary depending on the gas composition. becomes constant and the change in the pressure rise rate becomes smaller. Therefore, the timing to complete the temperature rise regeneration can be appropriately determined based on the history of the pressure rise rate.

The step of completing the temperature rise regeneration may include: repeating the steps of supplying the purge gas to the cryopump container 16 and then roughly pumping the cryopump container 16 and then measuring the pressure rise rate in the cryopump container 16 to obtain the pressure rise rate history; and based on The obtained history of the pressure rise rate determines whether to complete the regeneration step of the cryopump 10 . In this way, by repeating the cycle of flushing, rough pumping and pressure rise rate measurement, 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 obtained more accurately. When it is evaluated that the change in the pressure rise rate known from the obtained history of the pressure rise rate is sufficiently small, it can be determined that the gas trapped in the cryopanel 18 is sufficiently discharged from the cryopump 10 . In this way, the timing to complete the temperature rise regeneration can be determined.

The completion determination of temperature rise regeneration in the embodiment is particularly effective for determining whether harmful gases such as BF ₃ remain in the cryopump 10 . This is because these toxic gases usually have significantly different relative sensitivities from the reference gas (such as nitrogen) used for calibrating the pressure sensor 28. Therefore, the more toxic gases remain in the cryopump 10, the greater the change in the pressure rise rate. big tendency.

FIG. 3 is a flowchart showing an example of the completion determination process of the temperature rise regeneration shown in FIG. 2 . As described above, the completion determination process is started when the measured temperature of the cryopanel 18 reaches or exceeds the temperature rise completion temperature. Therefore, when the completion determination process is started, the purge gas is supplied from the purge gas source 23 to the cryopump container 16 through the flush valve 22 .

In this exemplary completion determination process, the controller 100 is configured to determine whether to complete regeneration of the cryopump based on the history of the pressure rise rate within the cryopump container 16 . In order to obtain the history of the pressure rise rate, the controller 100 is configured to repeatedly operate the flushing valve 22 , the rough valve 20 and the pressure sensor 28 while the cryopanel 18 is heating up to the heating completion temperature. After supplying the purge gas to the pump container 16, the cryopump container 16 is roughly pumped, and then the pressure rise rate in the cryopump container 16 is measured. During execution of the completion determination process, the pressure in the cryopump container 16 is measured periodically 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 obtain the change amount of the pressure increase rate every time the pressure increase rate is measured, and when the obtained change amount of the pressure increase rate is within the allowable range for a predetermined number of times (for example, at least 2 times). The regeneration of the cryopump 10 is completed.

As shown in FIG. 3 , in the completion determination process, first, the cryopump container 16 is rough pumped (S30). The controller 100 controls the valves to open the rough valve 20 and close the flush valve 22 . The cryopump container 16 is depressurized by the roughing pump 30 .

When the cryopump container 16 is depressurized to a predetermined rough pumping end pressure, the rough pumping of the cryopump container 16 may be ended. The rough extraction end pressure can be selected from a pressure range of 100 Pa or more and less than 1000 Pa, for example. In this pressure range, the relative sensitivity difference of the pressure sensor 28 (for example, a Pirani vacuum gauge) depending on the gas type becomes large, and is therefore suitable for this method. The controller 100 can compare the measured pressure in the cryopump container 16 with the rough pumping end pressure. When the measured pressure exceeds the rough pumping end pressure, continue the rough pumping of the cryopump container 16 (that is, open the rough pumping valve 20), and measure When the pressure reaches or falls below the rough pumping end pressure, the rough pumping of the cryopump container 16 ends (that is, the rough pumping valve 20 is closed).

Alternatively, the rough pumping of the cryopump container 16 may be completed based on the pressure drop rate of the cryopump container 16 (pressure drop amount per unit time). Generally, the higher the pressure within the cryopump container 16, the greater the pressure drop rate, and as the cryopump container 16 depressurizes, the pressure drop rate decreases. Therefore, rough pumping can be terminated based on a sufficient reduction in the pressure drop rate. The controller 100 may obtain the pressure drop rate from the measured pressure within the cryopump container 16 . The controller 100 can compare the obtained pressure drop rate with a pressure drop rate threshold. When the pressure drop rate exceeds the pressure drop rate threshold, rough pumping of the cryopump container 16 is continued. When the pressure drop rate is lower than the pressure drop rate threshold, the cryogenic pumping process is terminated. Rough pumping of the pump container 16.

Alternatively, the rough pumping of the cryopump container 16 may be completed when a predetermined rough pumping time has elapsed since the rough pumping was started. The controller 100 may compare the elapsed time from the start of rough pumping with the rough pumping time, continue rough pumping of the cryopump container 16 until the elapsed time reaches the rough pumping time, and end the cryopump container when the elapsed time reaches the rough pumping time. 16 rough. The controller 100 can compare the pressure in the cryopump container 16 measured at the end of rough pumping with the end of rough pumping, and when the measured pressure does not reach the end of rough pumping, supply purge gas to the cryopump container 16 and then proceed again. Rough pumping.

When the rough pumping of the cryopump container 16 is completed, the pressure rise rate in the cryopump container 16 is measured and the change amount of the pressure rise rate is obtained (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. To measure the pressure within a predetermined measurement time, the pressure rise rate can be obtained by dividing the pressure increment at the beginning and end of the measurement by the measurement time. The change amount of the pressure rise rate can be defined as the pressure rise measured in this measurement cycle relative to the pressure rise rate measured in the previous measurement cycle (that is, the cycle of purification, rough pumping and pressure rise rate measurement). A change in rate (e.g., difference or proportion). The controller 100 may be configured to calculate the change amount from the pressure rise rate of the previous time and this time.

In addition, in the first measurement cycle performed at the start of the completion determination process, the previous pressure rise rate used for calculating the change amount does not yet exist. Therefore, after measuring the pressure rise rate in the cryopump container 16 in the first measurement cycle, the process shifts to the second measurement cycle (that is, supplying the purge gas to the cryopump container 16 and performing rough pumping of the cryopump container 16 (S30). ), measure the pressure rise rate in the cryopump container 16, and obtain the change amount of the pressure rise rate (S32)).

Next, the change amount of the obtained pressure increase rate is evaluated (S34). This is the first test of the change in pressure rise rate. The controller 100 compares the obtained change amount of the pressure rise rate with the allowable range. When the change amount of the pressure rise rate is within the allowable range, it is determined that the test has passed. When the change amount of the pressure rise rate is outside the allowable range, it is determined that the test has passed. For failing the test.

The allowable range can be set in the form of a ratio, for example, it can be within ±30%, or within ±20%, or within ±10%. Alternatively, the allowable range can be set in the form of a value of the pressure rise rate, for example, it can be within ±30 Pa/min, or within ±20 Pa/min, or within ±10 Pa/min. The setting of this allowable range can be looser than the criterion for determining the pressure rise rate (for example, within 5 Pa/min) before starting the temperature reduction during normal regeneration (moisture content in the cryopump container 16 is allowed to remain during temperature rise regeneration, compared with normal regeneration). The water should also be drained out as much as possible). The controller 100 may determine that the change in the pressure rise rate is within the allowable range in terms of both the proportion and the absolute value. The controller 100 may also determine that the change in the pressure rise rate is within the allowable range in terms of either the proportion or the absolute value. Judged as qualified. Such an allowable range can be appropriately set based on the designer's empirical knowledge of the cryopump 10 or experiments and simulation experiments conducted by the designer, and can be stored in the controller 100 in advance.

Then, the measurement cycle is performed 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 change amount of the pressure rise rate is obtained (S40).

Then, the change amount of the obtained pressure increase rate is evaluated (S42). This is the second test of the change in pressure rise rate. Similar to the first test, the controller 100 compares the obtained change amount of the pressure rise rate with the allowable range. When the change amount of the pressure rise rate is within the allowable range, it is determined that the test has passed, and the pressure rise rate is When the amount of variation is outside the allowable range, the test is judged to have failed.

Next, it is determined whether the number of times that the obtained change amount of the pressure rise rate has been continuously within the allowable range reaches a predetermined number of times (in this example, two times) (S44). When either the first or second test fails (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 change amount of the pressure rise rate is obtained (S40).

On the other hand, when both the first and second tests pass (YES in S44), it can be considered that the pressure rise rate of the cryopump container 16 is stable for a period of time. As mentioned above, this may mean that the gas composition in the cryopump container 16 is substantially composed of purified gas, and therefore the temperature rise regeneration of the cryopump 10 can be completed (S44). In this case, as described with reference to FIG. 2 , the purge gas is supplied to the cryopump container 16 ( S16 in FIG. 2 ), and the refrigerator 14 is stopped ( S18 in FIG. 2 ). Afterwards, the cryopump 10 can be removed from the vacuum chamber 200 (S20 of FIG. 2).

According to this embodiment, by repeating the cycle of purification, rough pumping, and pressure rise rate measurement, the inside of the cryopump container 16 can be purified, and the completion can be appropriately determined based on the history of the pressure rise rate of the cryopump container 16 thus obtained. The timing of temperature rise and regeneration of the cryopump 10 . Reducing or minimizing the risk of toxic gas leakage that may occur when the cryopump 10 is removed from the vacuum chamber 200 can improve the safety of the process of removing the cryopump 10 .

In addition, if necessary, the temperature rise regeneration of the cryopump 10 may be completed when the obtained change amount of the pressure rise rate passes more consecutive times (for example, 3 times or more). By doing this, it can be determined more reliably that the pressure rise rate has stabilized.

The present invention has been described above based on the embodiments. The present invention is not limited to the above-described embodiments, and various design changes are possible. Those skilled in the art will understand that various modifications exist, and such modifications are also included in the scope of the present invention. [Industrial availability]

The present invention can be used in cryopump regeneration methods and in the field of cryopumps. This application claims priority based on Japanese Patent Application No. 2022-040910 filed on March 16, 2022. The entire contents of this Japanese application are incorporated by reference into this specification.

10:Cryogenic pump 16: Cryogenic pump container 18:Cryogenic plate 20: Rough pumping valve 22: Flushing valve 28: Pressure sensor 30: Rough pump 100:Controller 200: Vacuum chamber

[Fig. 1] schematically shows a cryopump according to the embodiment. [Fig. 2] This is a flowchart showing the temperature-raising regeneration of the cryopump according to the embodiment. [Fig. 3] This is a flowchart showing an example of the completion determination process of the temperature rise regeneration shown in Fig. 2.

10:Cryogenic pump

12:Compressor

14: Freezer

16: Cryogenic pump container

16a: Low temperature plate storage part

16b: Freezer storage part

17: Suction port

18:Cryogenic plate

20: Rough pumping valve

22: Flushing valve

23:Purify air source

24:Exhaust valve

26:Temperature sensor

28: Pressure sensor

30: Rough pump

32: Discharge line

100:Controller

200: Vacuum chamber

201: Chamber opening

202: Gate valve

Claims (8)

A method for regenerating a cryopump. The cryopump is provided with a cryogenic plate and a cryogenic pump container that accommodates the cryogenic plate. The method includes: The step of raising the temperature of the aforementioned cryogenic plate from extremely low temperature to the temperature at which the heating is completed; and The step of regenerating the cryopump is completed in a state where the temperature of the cryopanel is raised to the temperature rise completion temperature, The previously completed steps include: Repeating the steps of supplying purge gas to the cryopump container, roughly pumping the cryopump container, and then measuring the pressure rise rate in the cryopump container to obtain the history of the pressure rise rate; and Whether to complete the regeneration step of the cryopump is determined based on the obtained history of the pressure rise rate. The method as described in claim 1, wherein, The aforementioned obtaining step includes: obtaining the change amount of the aforementioned pressure rise rate each time the aforementioned pressure rise rate is measured, The step of determining includes the step of completing the regeneration of the cryopump when the obtained change amount of the pressure rise rate is continuously within the allowable range for a predetermined number of times. The method as described in request item 2, wherein, The aforementioned prescribed number of times is at least 2 times. The method described in any one of claims 1 to 3, wherein, When the pressure of the cryopump container drops to a pressure range of more than 100 Pa and less than 1000 Pa, rough pumping of the cryopump container is completed. The method according to any one of claims 1 to 4, further comprising the step of supplying purge gas to the cryopump container when regeneration of the cryopump is completed. The method described in any one of claims 1 to 5, wherein, The regeneration of the cryopump is performed in a state where the cryopump is installed in a vacuum chamber to be evacuated by the cryopump, The foregoing method further includes: after completing the regeneration of the foregoing cryopump, the step of removing the foregoing cryopump from the foregoing vacuum chamber. The method described in any one of claims 1 to 6, further comprising: As the regeneration program to be executed, any step of normal regeneration including recooling of the cryopump or temperature-raising regeneration excluding recooling of the cryopump is selected; and Perform the steps of the selected regeneration program, The aforementioned temperature-raising regeneration includes the aforementioned temperature-raising step and the aforementioned completing step. A cryogenic pump having: cryogenic plate; A cryogenic pump container to store the aforementioned cryogenic plate; A heat source to heat up the aforementioned cryogenic plate; A flushing valve to supply purge gas to the aforementioned cryogenic pump container; A rough pumping valve is used to discharge gas from the aforementioned cryogenic pump container to a rough pumping pump; A pressure sensor to measure the pressure in the aforementioned cryogenic pump container; and The controller is configured to operate the heat source in a manner to raise the temperature of the cryopanel from a very low temperature to a temperature rise completion temperature, and to complete the regeneration of the cryopump in a state where the cryopanel is heated to the temperature rise completion temperature, The aforementioned controller is composed of, By activating the flushing valve, the rough pumping valve and the pressure sensor, the purge gas is supplied to the cryopump container, the cryopump container is roughly pumped, and the pressure rise rate in the cryopump container is measured. The process of obtaining the aforementioned pressure rise rate, Whether to complete the regeneration of the cryopump is determined based on the obtained history of the pressure rise rate.

Images