JP6929601B2 - Cryopump - Google Patents

Description

The present invention relates to a cryopump.

The cryopump is a vacuum pump that captures and exhausts gas molecules by condensing or adsorbing on a cryopanel cooled to an extremely low temperature. Cryopumps are generally used to realize a clean vacuum environment required for semiconductor circuit manufacturing processes and the like. Since the cryopump is a so-called gas storage type vacuum pump, it is necessary to regenerate the captured gas by periodically discharging it to the outside.

Japanese Patent No. 5669658

One of the exemplary objects of an aspect of the present invention is to reduce the regeneration time of a cryopump.

According to an aspect of the present invention, the cryopump operates by recovering and compressing a cryopump housing, an expander attached to the cryopump housing, and working gas from the expander, and compressing the working gas into the expander. An ultra-low temperature refrigerator including a compressor for supplying gas, a purge gas line for supplying purge gas to the cryopump housing, and the purge gas line so as to heat the purge gas by utilizing the exhaust heat of the compressor. It is equipped with an installed heat exchanger.

It should be noted that any combination of the above components or components and expressions of the present invention that are mutually replaced between methods, devices, systems, and the like are also effective as aspects of the present invention.

According to the present invention, the regeneration time of the cryopump can be shortened.

The cryopump according to the first embodiment is shown schematically. The cryopump according to the second embodiment is shown schematically.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description and drawings, the same or equivalent components, members, and processes are designated by the same reference numerals, and duplicate description will be omitted as appropriate. The scales and shapes of the illustrated parts are set for convenience of explanation and are not interpreted in a limited manner unless otherwise specified. Embodiments are exemplary and do not limit the scope of the invention in any way. Not all features and combinations thereof described in the embodiments are necessarily essential to the invention.

(First Embodiment)
FIG. 1 schematically shows a cryopump 10 according to the first embodiment. The cryopump 10 includes at least one cryopump main body 12, a cryogenic refrigerator 14, and the cryopump main body 12 includes a cryopump housing 16. The cryogenic refrigerator 14 includes an expander 18 and a compressor 20. Further, the cryopump 10 includes a purge gas line 22, a cooling system 24, and a first heat exchanger 26.

The cryopump body 12 is attached to the vacuum chamber of, for example, an ion injection device, a sputtering device, a vapor deposition device, or other vacuum process device to increase the degree of vacuum inside the vacuum chamber to the level required for a desired vacuum process. Used for.

The cryopump housing 16 accommodates a cryogenic surface, also called a cryopanel. The gas entering from the intake port of the cryopump main body 12 is trapped on this cryogenic surface by condensation or adsorption. The expander 18 of the cryogenic refrigerator 14 is attached to the cryopump housing 16 so as to cool the cryopanel. The configuration of the cryopump main body 12, such as the arrangement and shape of the cryopanel, will not be described in detail here because various known configurations can be appropriately adopted.

The cryopump housing 16 includes a purge valve 28 for introducing purge gas into the cryopump housing 16, and a vent valve 30 for discharging fluid from the cryopump housing 16 to the outside. The cryopump housing 16 may include a rough valve or other valve, a pressure sensor or other sensor.

The compressor 20 of the cryogenic refrigerator 14 is configured to recover the working gas of the cryogenic refrigerator 14 from the expander 18, boost the recovered working gas, and supply the working gas to the expander 18 again. There is. The compressor 20 and the expander 18 constitute a working gas circulation circuit, that is, a refrigerating cycle of the cryogenic refrigerator 14, whereby the cooling stage of the expander 18 is cooled. The working gas is usually helium gas, but other suitable gases may be used. The cryogenic refrigerator 14 is, for example, a two-stage Gifford-McMahon (GM) refrigerator, but may be another cryogenic refrigerator.

The expander 18 of the cryogenic refrigerator 14 may be configured to enable so-called reverse temperature rise. In this case, when the motor 19 for driving the expander 18 rotates in the normal direction, a refrigeration cycle is formed by expanding the working gas, while when the motor 19 rotates in the reverse direction, a temperature rising cycle is formed by compressing the working gas. The expander 18 can switch between freezing and raising the temperature by switching the motor rotation direction. The reverse temperature rise of the expander 18 can be used as one of the heat sources for raising the temperature of the cryopump main body 12 during regeneration.

Further, the cryogenic refrigerator 14 includes a high-pressure pipe 32 and a low-pressure pipe 34. The high-pressure pipe 32 connects the compressor 20 to the expander 18 so as to supply the high-pressure working gas compressed by the compressor 20 from the compressor 20 to the expander 18. The low-pressure pipe 34 connects the compressor 20 to the compressor 18 so as to recover the low-pressure working gas decompressed by the expansion in the expander 18 from the expander 18 to the compressor 20.

The compressor 20 includes a compressor main body 36 that compresses working gas, a discharge gas flow path 38, an intake gas flow path 40, a compressor housing 42, and a second heat exchanger 44. The discharge gas flow path 38 connects the discharge port of the compressor main body 36 to the high pressure pipe 32, and the suction gas flow path 40 connects the suction port of the compressor main body 36 to the low pressure pipe 34. Compression heat is generated as the working gas is compressed by the compressor body 36. Therefore, the high-pressure working gas flowing through the discharge gas flow path 38 has a higher temperature than the low-pressure working gas flowing through the intake gas flow path 40. The compressor housing 42 houses the compressor main body 36, the discharge gas flow path 38, the suction gas flow path 40, and the second heat exchanger 44.

The purge gas line 22 is configured to supply purge gas to the cryopump housing 16. The purge gas is used to efficiently regenerate the cryopump 10. The purge gas is used as one of the heat sources for raising the temperature of the cryopump main body 12. Further, the purge gas can promote the re-vaporization of the gas trapped inside the cryopump main body 12 to discharge the gas. The purge gas is a gas that is usually different from the working gas of the cryogenic refrigerator 14, and is, for example, nitrogen gas.

The purge gas line 22 includes a purge gas source 46 and a purge gas pipe 48. The purge gas pipe 48 connects the purge gas source 46 to the purge valve 28 so as to supply the purge gas from the purge gas source 46 to the purge valve 28. By opening the purge valve 28, the purge gas flow from the purge gas source 46 to the cryopump housing 16 is allowed. By closing the purge valve 28, the purge gas flow from the purge gas source 46 to the cryopump housing 16 is cut off. The supplied purge gas can be discharged from the cryopump housing 16 through the vent valve 30.

The purge gas line 22 is installed in the ambient environment of the cryopump main body 12, for example, a room temperature atmospheric pressure environment. The temperature of the purge gas is adjusted to, for example, room temperature. If necessary, the purge gas may be a gas heated to a temperature higher than room temperature or a gas having a temperature lower than room temperature. In this document, the room temperature is a temperature selected from the range of 10 ° C. to 30 ° C. or the range of 15 ° C. to 25 ° C., for example, about 20 ° C.

The cooling system 24 is configured to cool the compressor 20 with a refrigerant so as to remove the heat of compression generated by the compression of the working gas in the compressor 20 from the compressor 20. The cooling system 24 includes a chiller 50 that regulates and circulates the refrigerant, a refrigerant supply flow path 52, a refrigerant recovery flow path 54, and a compressor refrigerant flow path 56. The refrigerant is, for example, cooling water. The refrigerant is cooled by the chiller 50, for example, to a temperature lower than room temperature and higher than the freezing point of the refrigerant (0 ° C in the case of water).

The refrigerant supply flow path 52 connects the chiller 50 to the compressor refrigerant flow path 56 so as to supply the temperature-controlled refrigerant from the chiller 50 to the compressor refrigerant flow path 56. The refrigerant recovery flow path 54 connects the chiller 50 to the compressor refrigerant flow path 56 so as to recover the refrigerant from the compressor refrigerant flow path 56 to the chiller 50. Of the cooling system 24, the chiller 50, the refrigerant supply flow path 52, and the refrigerant recovery flow path 54 are arranged outside the compressor 20, and the compressor refrigerant flow path 56 is arranged inside the compressor 20. The compressor refrigerant flow path 56 is housed in the compressor housing 42.

The second heat exchanger 44 is configured to exchange heat between the discharge gas flow path 38 and the compressor refrigerant flow path 56. The working gas flowing through the discharge gas flow path 38 is cooled by the refrigerant flowing through the compressor refrigerant flow path 56. Therefore, the refrigerant is heated by the second heat exchanger 44, and the heated refrigerant flows into the refrigerant recovery flow path 54. The refrigerant flowing through the refrigerant recovery flow path 54 is heated to a temperature higher than room temperature, for example, 50 ° C. to 70 ° C. Further, the working gas is cooled to an appropriate temperature by the second heat exchanger 44 and supplied to the expander 18 through the discharge gas flow path 38 and the high pressure pipe 32. In this way, the heat of compression generated in the compressor body 36 is transported from the working gas to the refrigerant via the second heat exchanger 44, and is removed from the compressor 20 together with the refrigerant flowing out of the compressor 20.

The first heat exchanger 26 is installed in the purge gas line 22 so as to heat the purge gas by utilizing the exhaust heat of the compressor 20. The first heat exchanger 26 is configured to heat the purge gas using the refrigerant heated by the heat of compression as a heat source.

The first heat exchanger 26 is arranged outside the compressor 20. The first heat exchanger 26 may be installed in the compressor 20 adjacent to the outside of the compressor housing 42.

The first heat exchanger 26 is configured to exchange heat between the refrigerant recovery flow path 54 and the purge gas pipe 48. The purge gas flowing through the purge gas pipe 48 is heated by the refrigerant flowing through the refrigerant recovery flow path 54. The purge gas sent from the purge gas source 46 to the purge gas pipe 48 is heated by the first heat exchanger 26, and the heated purge gas is supplied from the purge valve 28 to the cryopump housing 16. The purge gas supplied from the purge gas line 22 to the cryopump housing 16 is heated to a temperature higher than room temperature, for example, 40 ° C. to 60 ° C. The refrigerant is cooled by the first heat exchanger 26 and returns to the chiller 50. In this way, the purge gas is heated by utilizing the exhaust heat of the compressor 20 transported to the refrigerant.

As the first heat exchanger 26, any applicable type of heat exchanger can be appropriately adopted. Similarly, the second heat exchanger 44 can appropriately adopt any applicable form of heat exchanger.

As the exhaust operation of the cryopump 10 is continued, gas is accumulated in the cryopump main body 12. The cryopump main body 12 is regenerated in order to discharge the accumulated gas to the outside. When the regeneration is completed, the exhaust operation can be started again.

When regeneration is started, purge gas is supplied from the purge gas line 22 to the cryopump housing 16. The cryopump main body 12 is heated by the reverse temperature rise of the expander 18 of the cryogenic refrigerator 14. The operation of the compressor 20 is continued even during the reproduction. The refrigerant of the cooling system 24 is heated in the second heat exchanger 44 by the heat of compression of the working gas. The purge gas is heated in the first heat exchanger 26 by the heated refrigerant. In this way, the purge gas can be heated by utilizing the exhaust heat of the compressor 20, and the heated purge gas can be supplied to the cryopump housing 16. Since the high temperature purge gas is supplied, the temperature rise of the cryopump main body 12 during regeneration can be accelerated.

If the first heat exchanger 26 is not installed in the purge gas line 22, purge gas at room temperature is supplied to the cryopump main body 12. On the other hand, according to the cryopump 10 according to the first embodiment, it is possible to supply a high temperature purge gas to the cryopump main body 12 as compared with the case where the first heat exchanger 26 is not provided. Therefore, it is expected that the temperature of the cryopump main body 12 can be raised efficiently and the regeneration time can be shortened.

Further, according to the cryopump 10 according to the first embodiment, the exhaust heat of the compressor 20 that has been discarded to the outside can be utilized. The cryopump 10 is excellent in energy saving as compared with other heating means such as installing an electric heater in the purge gas line 22.

Further, according to the cryopump 10 according to the first embodiment, the existing purge gas line 22 can be used almost as it is. No major modification of the purge gas line 22 is required. Negative effects such as increased installation space and increased costs can be minimized.

(Second Embodiment)
FIG. 2 schematically shows a cryopump 10 according to a second embodiment. The cryopump 10 shown is different from the cryopump 10 shown in FIG. 1 in terms of the configuration of the first heat exchanger 26, and the rest is generally common. In the following, different configurations will be mainly described, and common configurations will be briefly described or omitted.

The cryopump 10 includes a cryopump main body 12 including a cryopump housing 16, and a cryogenic refrigerator 14 including an expander 18 and a compressor 20. The inflator 18 is attached to the cryopump housing 16. The cryopump housing 16 is provided with a purge valve 28 and a vent valve 30. Further, the cryopump 10 includes a purge gas line 22, a cooling system 24, and a first heat exchanger 26.

The compressor 20 includes a compressor main body 36, a discharge gas flow path 38, an intake gas flow path 40, and a compressor housing 42. The discharge gas flow path 38 connects the discharge port of the compressor main body 36 to the high pressure pipe 32, and the suction gas flow path 40 connects the suction port of the compressor main body 36 to the low pressure pipe 34.

The compressor 20 is provided with both a first heat exchanger 26 and a second heat exchanger 44. The compressor housing 42 houses the compressor main body 36, the discharge gas flow path 38, the suction gas flow path 40, the first heat exchanger 26, and the second heat exchanger 44.

The purge gas line 22 includes a purge gas source 46 and a purge gas pipe 48. The purge gas pipe 48 includes a compressor purge gas flow path 58 arranged in the compressor 20. The compressor purge gas flow path 58 is housed in the compressor housing 42. The purge gas is supplied from the purge gas source 46 to the purge valve 28 through the compressor purge gas flow path 58 and the purge gas pipe 48. The purge gas is supplied from the purge valve 28 to the cryopump housing 16.

The cooling system 24 includes a chiller 50, a refrigerant supply flow path 52, a refrigerant recovery flow path 54, and a compressor refrigerant flow path 56. Unlike the first embodiment, in the second embodiment, the first heat exchanger 26 is not provided in the cooling system 24.

The first heat exchanger 26 is installed in the purge gas line 22 so as to heat the purge gas by utilizing the exhaust heat of the compressor 20. The first heat exchanger 26 is configured to heat the purge gas using the working gas compressed by the compressor 20 as a heat source.

The first heat exchanger 26 is configured to exchange heat between the discharge gas flow path 38 and the compressor purge gas flow path 58. The purge gas flowing through the compressor purge gas flow path 58 is heated by the working gas flowing through the discharge gas flow path 38. The purge gas sent from the purge gas source 46 to the purge gas pipe 48 is heated by the first heat exchanger 26, and the heated purge gas is supplied from the purge valve 28 to the cryopump housing 16. The working gas is cooled by the first heat exchanger 26 and flows to the second heat exchanger 44.

The second heat exchanger 44 is configured to exchange heat between the discharge gas flow path 38 and the compressor refrigerant flow path 56. The working gas flowing through the discharge gas flow path 38 is cooled by the refrigerant flowing through the compressor refrigerant flow path 56. Therefore, the refrigerant is heated by the second heat exchanger 44, and the heated refrigerant flows into the refrigerant recovery flow path 54. Further, the working gas is cooled to an appropriate temperature by the second heat exchanger 44 and supplied to the expander 18 through the discharge gas flow path 38 and the high pressure pipe 32.

Both the first heat exchanger 26 and the second heat exchanger 44 are installed in the discharge gas flow path 38 of the compressor 20. The first heat exchanger 26 is arranged upstream of the second heat exchanger 44. That is, the first heat exchanger 26 is located between the compressor main body 36 and the second heat exchanger 44. Since the first heat exchanger 26 is provided immediately downstream of the compressor body 36, the first heat exchanger 26 can bring the purge gas into thermal contact with the higher temperature working gas. Therefore, the first heat exchanger 26 can heat the purge gas to a higher temperature.

If it is desired to suppress an excessive temperature rise of the purge gas due to restrictions due to the heat resistant temperature of the cryopump main body 12, the positional relationship between the first heat exchanger 26 and the second heat exchanger 44 may be reversed. .. That is, the first heat exchanger 26 may be arranged downstream of the second heat exchanger 44. The second heat exchanger 44 may be located between the compressor body 36 and the first heat exchanger 26.

According to the cryopump 10 according to the second embodiment, the purge gas can be heated by utilizing the exhaust heat of the compressor 20, and the heated purge gas can be supplied to the cryopump housing 16. Since the high temperature purge gas is supplied, the temperature rise of the cryopump main body 12 during regeneration can be accelerated. Therefore, it is expected that the temperature of the cryopump main body 12 can be raised efficiently and the regeneration time can be shortened. Further, the cryopump 10 is excellent in energy saving as compared with other heating means such as installing an electric heater in the purge gas line 22.

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

Although one cryopump main body 12 is shown in the figure, the cryopump 10 may include a plurality of cryopump main bodies 12. In this case, the cryogenic refrigerator 14 includes at least one compressor 20 and a plurality of expanders 18. Each inflator 18 is attached to the corresponding cryopump housing 16 of the corresponding cryopump body 12. The plurality of cryopump main bodies 12 can be operated independently. For example, while one cryopump main body 12 is being regenerated, the remaining cryopump main bodies 12 can continue the vacuum exhaust operation.

10 Cryopump, 14 Cryogenic refrigerator, 16 Cryopump housing, 18 Inflator, 20 Compressor, 22 Purge gas line, 24 Cooling system, 26 First heat exchanger.

Claims (1)

Cryopump housing and
A cryogenic refrigerator including an expander attached to the cryopump housing, a compressor that collects and compresses working gas from the expander, and supplies the compressed working gas to the expander.
A purge gas line that supplies purge gas to the cryopump housing,
A heat exchanger installed in the purge gas line so as to heat the purge gas by utilizing the exhaust heat of the compressor is provided .
The heat exchanger, a cryopump, characterized that you have been configured to heat the purge gas working gas compressed as a heat source by the compressor.

Images