JP3295136B2 - Cryopump regeneration method and regeneration device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryopump regeneration method and apparatus.

[0002]

2. Description of the Related Art A cryopump having a high-temperature side cooling unit and a low-temperature side cooling unit cooled by a small helium refrigerator is used for many evacuation operations. As shown in FIG. 5, in this type of cryopump 20, the cylindrical pump container 2 is attached to the helium refrigerator 3 and the pump container 2
Is provided with a high-temperature side cooling section, that is, a first-stage cryopanel 4, and a low-temperature side cooling section, that is, a second
A step cryopanel 5 is provided.

In such a configuration, the cryopump condenses various gases to be exhausted on the surfaces of the cryopanels 4 and 5 or adsorbs them on an adsorbent 9 provided inside the second-stage cryopanel 5. Because it is a vacuum pump that exhausts by storing, if the amount of stored gas increases,
Since the amount of exhaust gas is reduced and the ultimate pressure cannot be obtained, a regeneration operation is required to extract the stored gas and exhaust the gas again. Regeneration of the cryopump
This is performed by returning the temperature of the cryopump to room temperature, converting the gas stored by condensation or adsorption into a gas or liquid (particularly in the case of water), and taking it out of the pump and removing it.

[0004] The method of raising the temperature of the cryopump to room temperature includes a method of mounting a heater or the like on the outer surface of a pump container of the cryopump and heating from the outside, or a method of introducing an inert gas such as nitrogen into the cryopump. Heating of these heaters and gas introduction are used in combination as a method of heating and raising the temperature by the amount of heat, or as a more efficient regeneration.

[0005] Among these methods, a gas introduction method is shown in FIG. 5 in which a gas introduction pipe 11a and a gas outlet pipe 12a are attached in a pump vessel 2 of a cryopump 20, and nitrogen or the like heated from the gas introduction pipe 11a. When an inert gas is introduced into the pump vessel 2 and the temperature inside the vessel 2 rises, the condensed gas is vaporized and is taken out of the pump out of the pump together with the nitrogen and removed. Gases with a high vapor pressure, such as argon, nitrogen, and hydrogen, are completely vaporized if the inside of the pump container 2 is heated to room temperature, and are discharged out of the pump container 2 together with the introduced nitrogen gas. You.

[0006]

However, water is most difficult to remove from the cryopump. Since water is mostly liquid at room temperature and has a low vapor pressure, it takes time to evaporate and dry it with a flow of nitrogen gas. Also, since it is difficult to determine whether all the water has evaporated, how many hours of nitrogen introduction time are required after the pump has returned to room temperature is empirically determined. In addition, since the amount of exhausted water changes with each regeneration, it is necessary to expect a considerable safety factor in the gas introduction time. For this reason, there has been a problem that the gas introduction time requires an unnecessarily long time and the operation rate of the apparatus is lowered.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and the introduction of an inert gas such as nitrogen gas into and out of a pump vessel makes it possible to regenerate a cryopump with a longer regeneration time than before. An object of the present invention is to provide a method and apparatus for regenerating a cryopump that can be shortened.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for regenerating a cryopump having a cooling section cooled by a refrigerator in a pump container, the step of introducing a heated inert gas into the pump container. When the pressure in the pump container reaches the atmospheric pressure due to the inert gas, a step of extracting the heated inert gas to the outside from the pump container and introducing the heated inert gas into the pump container. A step of detecting the moisture when the introduction of the active gas is started, a step of detecting a change in the moisture in the pump container after the derivation of the inert gas, and the moisture becomes the moisture at the start of the introduction of the inert gas. And a step of detecting that the cryopump has been regenerated.

Another object of the present invention is to provide a cryopump in which a heated inert gas is introduced into a pump container of a cryopump having a cooling unit cooled by a refrigerator, and the inert gas is derived and regenerated. In the regenerating apparatus of (1), the regenerating apparatus for a cryopump is provided with a moisture detector for detecting a change in moisture in the pump container.

[0010]

Since the change in the water in the pump container is detected, if water remains in the pump container during the introduction and discharge of the inert gas, the water is present in the pump gas. A change in moisture can be detected. The moisture concentration after the introduction of the inert gas once rises, the inside of the pump container starts to dry, and decreases to the same level as the moisture when the inert gas was introduced. By detecting the change of the water inside the pump container during the introduction and discharge of the inert gas, it is possible to know when the inside of the pump container has dried, and at this point, the introduction of the inert gas is stopped.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A cryopump regeneration method and apparatus according to a first embodiment of the present invention will be described below with reference to the drawings. Note that the same components as those of the conventional example are denoted by the same reference numerals and described.

In FIG. 1, a cryopump according to the present embodiment is indicated by 1 as a whole, and a cylindrical pump vessel 2 having a flange portion 2a is mounted on a helium refrigerator 3, which has a low-temperature expansion chamber. A first stage refrigeration stage 7 and a second stage refrigeration stage 8 provided adjacent to each other
Is attached so as to be inserted into the inside of the pump container 2. Further, a cooling unit that is cooled by the freezing stages 7 and 8 by heat conduction is provided in the pump container 2. To briefly explain the structure of the cooling unit, a first-stage cryopanel 4 and a second-stage cryopanel 5 made of a thin plate of oxygen-free copper or aluminum metal plate are arranged in a pump container 2. The outer first-stage cryopanel 4 is formed in a cup shape, is disposed upward on the first-stage freezing stage 7, and a baffle 6 is provided at an upper end thereof.

A second-stage cryopanel 5 is formed in a cup shape inside the first-stage cryopanel 4, and is disposed on the second-stage refrigeration stage 8 in a downward direction. An adsorbent 9 such as activated carbon or molecular sieve is provided inside the second-stage cryopanel.

The structure of the regenerating apparatus F for regenerating the cryopump 1 will be described. Nitrogen gas is introduced through the left bottom of the pump vessel 2 in the drawing and the left bottom of the first cryopanel 4. One end of the gas introduction pipe 11a is provided. The gas introduction pipe 11a is disposed at the bottom of the pump container 2 in a gas-tight manner with the outside air, and is connected to a heating nitrogen supply source (not shown) via a pipe 11b and a gas introduction valve 13. The gas introduction valve 13 controls supply and stop of the nitrogen gas introduced into the pump container 2 by opening and closing the valve. Further, a gas outlet pipe 12a for leading out the gas introduced into the pump container 2 is provided at the right bottom of the pump container 2.
Is disposed so as to penetrate the bottom, and the bottom and the gas outlet pipe 12a are disposed airtightly with the outside air. A gas outlet valve 14 is connected to the discharge side end of the gas outlet pipe 12a, and a moisture detector 10 (hereinafter, referred to in this specification) is connected to the outlet side of the gas outlet valve 14 via a pipe 12b. , The moisture detector includes a humidity detector and the like, and the like.) The opening and closing of the gas outlet valve 14 controls discharge and stop of nitrogen gas. An atmospheric pressure checker PS for checking whether the inside of the pump container 2 is at atmospheric pressure is connected to the gas outlet pipe 12a.

In the cryopump 1 configured as described above, the flange 2a of the pump vessel 2 is connected to a vacuum device (not shown) via a main valve, and a refrigeration cycle is circulated outside the cryopump 1. Is connected to the compressor.

The cryopump 1 according to the first embodiment of the present invention is configured as described above. Next, the operation thereof will be described.

After the pressure inside the vacuum device (not shown) to which the cryopump 1 is attached is reduced to a predetermined pressure (rough evacuation), the refrigeration cycle of the cryopump 1 is started. Thereby, the first refrigerating stage 7 and the second refrigerating stage 8 are each cooled to a predetermined temperature. Desirable temperatures of the cryopanels 4 and 5 are 70K to 90K for the first cryopanel 4 and 10K to 20K for the second cryopanel 5.

When the cryopump 1 is operated, the baffle 6 and the first-stage cryopanel 4 condense and solidify water vapor, carbon dioxide, and the like having a high condensing temperature, of the gas molecules flowing through the opening, and the condensing temperature becomes higher. Low condensable gas such as oxygen, nitrogen, argon etc.
Condenses and solidifies. Hydrogen and helium, which have the lowest condensing temperatures than these condensable gases, cannot be condensed in the cryopanels 4 and 5, and are adsorbed by the adsorbent 9.

As described above, the cryopump 1 operates,
When the gas is condensed and solidified or adsorbed on each of the cryopanels 4 and 5 and the adsorbent 9 and the amount thereof increases, the exhaust speed of the gas may decrease or the ultimate pressure may not be obtained. Work is required. Less than,
The reproduction procedure will be described.

When the operation of the cryopump 1 is stopped and the gas introduction valve 13 is opened, heated nitrogen gas is introduced into the pump vessel 2 which is a substantially vacuum space. At this point, the gas outlet valve 14 remains closed,
The inside of the pump container 2 and the inside of the gas outlet pipe 12a have the same pressure. When it is confirmed by the atmospheric pressure checker PS that the inside of the pump vessel 2 has reached the atmospheric pressure, the gas outlet valve 14 is opened, and nitrogen gas is led out of the pump vessel 2 through the gas outlet pipe 12a. The nitrogen gas is exhausted through the gas outlet valve 14 and the moisture detector 10. At this time, the amount of moisture, that is, the humidity detected by the moisture detector 10 is the humidity of the nitrogen gas since the condensed gas has not been vaporized yet.

The temperature inside the pump vessel 2 is increased by the introduction of nitrogen gas, and the end of the gas introduction pipe 11a penetrates through the bottom of the cup-shaped first cryopanel 4 and the gas outlet pipe 12a is connected to the pump. Since the gas is disposed between the inner wall of the container 2 and the bottom of the first cryopanel 4, the nitrogen gas flows through the panel surfaces of the first and second cryopanels 4 and 5, where it condenses and solidifies. Alternatively, the gas such as water adsorbed by the adsorbent is vaporized by the calorific value of the nitrogen gas and is exhausted from the gas outlet pipe 12a to the outside of the pump container 2 together with the nitrogen gas.

The amount of water discharged and vaporized together with the nitrogen gas out of the pump vessel 2 will be described in detail with reference to FIG. 2. Regeneration of AB immediately after the gas introduction valve 13 and the gas discharge valve 14 are opened. In the start state, the temperature rise in the pump container 2 is small, and the humidity detected by the moisture detector 10 is the amount of the humidity of the nitrogen gas. When the inside of the pump container 2 starts to exceed 0 ° C. (point B) due to the amount of heat of the nitrogen gas,
Evaporation of water begins and the amount of evaporation increases. Thereby, as shown in B to C, the humidity detected by the moisture detector 10 becomes higher than the humidity level of the introduced nitrogen gas and gradually reaches the high level. In this high level state, as shown between C and D, the introduction and desorption of nitrogen into the pump vessel 2 is continued, so that the pump vessel 2
The water inside is also discharged together with the nitrogen gas. Eventually, as the water in the pump container 2 decreases, the humidity of the nitrogen gas discharged decreases as shown between D and E, and the amount of humidity detected by the moisture detector 10 becomes the same as the initial nitrogen humidity level. It is detected that E has reached the same level. At this point, pump container 2
Since the removal of water from the inside has been completed, the gas introduction valve 1
3 and the gas outlet valve 14 are closed.

As described above, in this embodiment, the moisture in the nitrogen gas to be released can be detected by the moisture detector 10, and the introduction and discharge of the nitrogen gas are continued, and the moisture in the pump vessel 2 is completely evaporated. When the water is removed, the water concentration in the nitrogen-derived gas decreases to the same level as the water concentration of the introduced nitrogen gas, so that it can be known that the inside of the pump is completely dried. By stopping the introduction of the nitrogen gas at this point, it is not necessary to take a safety factor for the gas introduction time, and the introduction time of the nitrogen gas, that is, the regeneration time of the cryopump can be shortened. Removal can be performed efficiently and reliably.

After the above operation is completed, the pump container 2
The inside of the pump is roughed to a predetermined pressure by a roughing pump (not shown), and when the roughing is completed, the cryopump 1 is started and the inside of the pump vessel 2 is cooled. When the cooling is completed, the cryopump 1 is ready to exhaust gas, and the regeneration of the cryopump 1 is completed.

Next, a method and an apparatus for regenerating a cryopump according to a second embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 3, the cryopump according to the present embodiment is indicated by 21 as a whole.
The structure of the regenerating apparatus G for regenerating water will be described. A hole 16 penetrating the peripheral wall of the pump container 15 is provided, and the detecting section of the moisture detector 10a faces the hole 16 to detect the moisture. The vessel 10a is attached. In the first embodiment, the humidity of the nitrogen gas introduced into the hole 16 from inside the pump vessel 2 is detected instead of detecting the humidity of the nitrogen gas by connecting to the pipe of the gas outlet pipe.
The regenerating apparatus G of the cryopump 21 according to the present embodiment is configured as described above, but other configurations such as a cooling unit of the cryopump 21 are similar to those of the first embodiment. The same is true for

It is most efficient to mount the moisture detector on the pipe on the side of the gas outlet pipe as in the first embodiment. However, even with the structure according to the present embodiment, it is known that the inside of the pump container 15 has been completely dried. It is not necessary to take a safety factor with respect to the gas introduction time, and the nitrogen gas introduction time can be reduced, that is, the regeneration time of the cryopump 21 can be reduced, and the water in the pump container 15 can be efficiently and reliably removed. Obviously you can.

Next, a method and apparatus for regenerating a cryopump according to a third embodiment of the present invention will be described with reference to FIG. The cooling unit of the cryopump has the same configuration as that of the first embodiment, and a detailed description thereof will be omitted.

Referring to FIG. 4, the structure of a regenerating device H for regenerating the cryopump 22 according to the present embodiment will be described. The regenerating device H is attached to a vacuum device 25 via a manifold 27 and a vacuum valve 26. Manifold 27
Is connected to one end of a gas introduction pipe 29a for introducing heated nitrogen gas. Gas inlet pipe 29a
Is connected airtight to the outside air on a peripheral wall 27a of the manifold 27, and is connected to a heating nitrogen supply source (not shown) via a pipe 29b and a gas introduction valve 31. The gas introduction valve 31 opens and closes the pump container 24 by opening and closing the valve.
Controls supply and stop of nitrogen gas introduced into the chamber. Further, the peripheral wall 27 facing the peripheral wall 27a of the manifold 27
In b, one end of a gas outlet pipe 30a that guides the gas introduced from the manifold 27 into the pump container 24 and returned to the manifold 27 to the outside is disposed on the peripheral wall 27b in a gas-tight manner with the outside air. A gas outlet valve 32 is connected to the discharge side end of the gas outlet pipe 30a, and a moisture detector 28 is attached to the outlet side of the gas outlet valve 32 via a pipe 30b.

The configuration of the third embodiment of the present invention has been described above. In the third embodiment, however, it can be seen that the inside of the pump container 24 has been completely dried by the same regeneration process as in the first embodiment. It is not necessary to take a safety factor with respect to the gas introduction time, and the nitrogen gas introduction time can be reduced, that is, the regeneration time of the cryopump 22 can be shortened, and the water in the pump container 24 can be efficiently and reliably removed. It is clear.

Although the embodiments of the present invention have been described above, the present invention is, of course, not limited to these, and various modifications can be made based on the technical concept of the present invention.

For example, in each of the embodiments described above, nitrogen gas is used as the inert gas introduced into the pump container. However, this is not limited to nitrogen gas, and other inert gases can be used. Further, the present invention can also be applied to the regeneration of the cryopump using both the heater heating and the gas described in the conventional example.

In the first and third embodiments, the moisture detector is mounted on the discharge side of the gas outlet valve. However, it may be installed between the cryopump and the gas outlet valve.

In the second embodiment, the gas detector is provided with a hole formed in the peripheral wall of the pump container. However, the gas detector may be provided in the pump container. For example, the detection unit of the moisture detector may be provided in the pump container. It may be attached to another position in the pump container such as a wall portion or a second refrigeration stage. In this case, the moisture detection signal may be derived from the lead wire which is inserted into the pump container in an airtight manner.

[0035]

As described above, according to the method and the apparatus for regenerating a cryopump according to the present invention, the change in the water content of the inert gas in the pump vessel of the cryopump is detected, whereby the inside of the pump vessel is detected. It is possible to know that the water has been removed, and it is possible to stop the gas introduction when the water has run out of the pump container. Thereby, the regeneration time of the cryopump can be greatly reduced, and the operation rate can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic partially broken front view of a main part of a cryopump according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a change in humidity of nitrogen gas introduced and led into the pump container.

FIG. 3 is a schematic partial cutaway front view of a main part of a cryopump according to a second embodiment of the present invention.

FIG. 4 is a schematic front view of a main part of a cryopump according to a third embodiment of the present invention.

FIG. 5 is a schematic partial cutaway front view of a main part of a conventional cryopump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cryopump 2 Pump container 3 Refrigerator 4 1st-stage cryopanel 5 2nd-stage cryopanel 6 Baffle 10 Moisture detector 10a Moisture detector 15 Pump container 21 Cryopump 22 Cryopump 24 Pump container 28 Moisture detector F regenerator G playback device H playback device

Claims (2)

(57) [Claims] 1. A method for regenerating a cryopump having a cooling unit cooled by a refrigerator in a pump container,
A step of introducing a heated inert gas into the pump container, and when the pressure in the pump container reaches the atmospheric pressure due to the inert gas, the pump inert gas is introduced from the pump container while the heated inert gas is being introduced. And a step of detecting the moisture when the introduction of the heated inert gas into the pump container is started, and a step of detecting a change in the moisture in the pump container after the introduction of the inert gas. Detecting that the moisture has become the moisture at the start of the introduction of the inert gas. 2. A cryopump regenerating apparatus in which a heated inert gas is introduced into a pump vessel of a cryopump having a cooling unit cooled by a refrigerator and the inert gas is derived and regenerated. A cryopump regeneration apparatus, further comprising a moisture detector for detecting a change in moisture in the pump container.