TWI697620B - Cryopump - Google Patents

Abstract

The present invention provides a cryopump whose problem is to shorten the regeneration time of the cryopump. The cryopump (10) of the present invention includes: a cryopump housing (16); an extremely low temperature refrigerator (14), which includes: an expander (18), which is installed in the cryopump housing (16); ), recover and compress the working gas from the expander (18), and supply the compressed working gas to the expander (18); flush the gas pipeline (22), supply the flushing gas to the cryopump housing (16); And the first heat exchanger (26) is arranged in the flushing gas pipeline (22) to heat the flushing gas by using the exhaust heat of the compressor (20).

Description

Cryopump

The present invention relates to a cryopump.

The cryopump is a vacuum pump that captures gas molecules for exhaust by condensing or adsorbing on a cryogenic plate that is cooled to an extremely low temperature. Cryogenic pumps are usually used to achieve a clean vacuum environment required by semiconductor circuit manufacturing processes. The cryopump is a so-called gas-trapping vacuum pump, which needs to be regenerated to periodically discharge the captured gas to the outside. (Prior technical literature) (Patent Document) Patent Document 1: Japanese Patent No. 5669658

(Problem to be solved by the present invention) One of the illustrative purposes of one aspect of the present invention is to shorten the regeneration time of the cryopump. (Means to solve the problem) According to one aspect of the present invention, the cryopump includes: a cryopump housing; an extremely low temperature refrigerator including: an expander installed in the cryopump housing; and a compressor for recovering and compressing working gas from the expander, The compressed working gas is supplied to the expander; the flushing gas pipeline is used to supply the flushing gas to the cryopump housing; and the heat exchanger is arranged to heat the flushing gas by using the exhaust heat of the compressor In the aforementioned flushing gas pipeline. In addition, it is equally effective as an aspect of the present invention to replace any combination of the above constituent elements, the constituent elements, and the expression form of the present invention between methods, devices, systems, and the like. (Effect of Invention) According to the present invention, the regeneration time of the cryopump can be shortened.

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 constituent elements, members, and processing are designated with the same symbols, and repeated descriptions are appropriately omitted. The scales and shapes of the depicted parts are simply set for ease of explanation, and unless otherwise specified, they are interpreted as non-limiting. The embodiment is an example and does not limit the scope of the present invention in any way. All the features and combinations described in the embodiments are not necessarily the essence of the invention. (First Embodiment) Fig. 1 schematically shows the cryopump 10 of the first embodiment. The cryopump 10 includes at least one cryopump body 12 and a cryogenic refrigerator 14, and the cryopump body 12 includes a cryopump housing 16. The cryogenic refrigerator 14 includes an expander 18 and a compressor 20. In addition, the cryopump 10 includes a flushing gas line 22, a cooling system 24 and a first heat exchanger 26. The cryopump body 12 is to increase the vacuum chamber installed in, for example, an ion implantation device, a sputtering device, an evaporation device, or other vacuum processing devices, and to increase the vacuum inside the vacuum chamber to the level required for the desired vacuum processing. And use. The cryopump housing 16 contains an extremely low temperature surface also called a cryoplate. The gas entering from the air inlet of the cryopump body 12 is captured to the extremely low temperature surface by condensation or adsorption. The expander 18 of the cryogenic refrigerator 14 is installed in the cryopump housing 16 to cool the cryoplate. The structure of the cryopump main body 12, such as the arrangement and shape of the cryoplate, can appropriately adopt various well-known structures, which will not be repeated here. The cryopump housing 16 includes a flush valve 28 for introducing flushing 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 be provided with a roughing valve or other valves, a pressure sensor or other sensors. The compressor 20 of the cryogenic refrigerator 14 is configured to recover the working gas of the cryogenic refrigerator 14 from the expander 18, pressurize the recovered working gas, and supply the working gas to the expander 18 again. The compressor 20 and the expander 18 constitute the circulating circuit of the working gas, that is, the refrigeration cycle of the cryogenic refrigerator 14, whereby the cooling stage of the expander 18 is cooled. The working gas is usually helium, but other suitable gases can also be used. As an example, the extremely low temperature refrigerator 14 is a type two Gifford-McMahon (GM) refrigerator, but other extremely low temperature refrigerators may also be used. The expander 18 of the cryogenic refrigerator 14 is configured to be able to perform so-called reverse temperature rise. In this case, when the motor 19 of the expander 18 is driven to rotate forward, a refrigeration cycle caused by the expansion of the working gas is formed. On the other hand, when the motor 19 is reversed, it is caused by the compression of the working gas. Heating cycle. By switching the motor rotation direction, the expander 18 can switch between freezing and heating. The reversal temperature rise of the expander 18 can be used as one of the heat sources for raising the temperature of the cryopump body 12 during regeneration. In addition, 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 that the high-pressure working gas compressed by the compressor 20 is supplied from the compressor 20 to the expander 18. The low-pressure pipe 34 connects the compressor 20 to the expander 18 so that the low-pressure working gas decompressed by the expansion in the expander 18 is recovered from the expander 18 to the compressor 20. The compressor 20 includes a compressor main body 36 that compresses working gas, a discharged gas flow path 38, a suction gas flow path 40, a compressor frame 42, and a second heat exchanger 44. The discharge gas flow path 38 connects the discharge port of the compressor body 36 to the high-pressure pipe 32, and the suction gas flow path 40 connects the suction port of the compressor body 36 to the low pressure pipe 34. Compression of the working gas by the compressor body 36 generates compression heat. Therefore, compared with the low-pressure working gas flowing in the suction gas flow path 40, the high-pressure working gas flowing in the discharge gas flow path 38 becomes high temperature. The compressor housing 42 houses the compressor main body 36, the discharged gas flow path 38, the suction gas flow path 40, and the second heat exchanger 44. The flushing gas line 22 is configured to supply flushing gas to the cryopump housing 16. In order to efficiently perform regeneration of the cryopump 10, flushing gas is used. The flushing gas is used as one of the heat sources for raising the temperature of the cryopump body 12. In addition, the flushing gas can promote the regasification and discharge of the gas trapped in the cryopump body 12. The flushing gas is usually a gas different from the working gas of the cryogenic refrigerator 14, such as nitrogen. The flushing gas pipeline 22 includes a flushing gas source 46 and a flushing gas pipe 48. The flushing gas pipe 48 connects the flushing gas source 46 to the flushing valve 28 so that the flushing gas is supplied from the flushing gas source 46 to the flushing valve 28. By opening the flushing valve 28, the flushing gas is allowed to flow from the flushing gas source 46 toward the cryopump housing 16. By closing the flushing valve 28, the flow of flushing gas from the flushing gas source 46 toward the cryopump housing 16 is blocked. The supplied flushing gas can be discharged from the cryopump housing 16 through the vent valve 30. The flushing gas pipeline 22 is arranged in the surrounding environment of the cryopump body 12, such as a room temperature and atmospheric pressure environment. The temperature of the flushing gas is adjusted to room temperature, for example. According to needs, the flushing gas can be a gas heated to a temperature higher than room temperature, or a gas with a temperature lower than room temperature. In this specification, 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 in the compressor 20 accompanying the compression of the working gas from the compressor 20. The cooling system 24 includes a cooler 50 that adjusts the temperature of the refrigerant and circulates it, 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 cooler 50, for example, to a temperature lower than room temperature and higher than the freezing point of the refrigerant (in the case of water, 0°C). The refrigerant supply flow path 52 connects the cooler 50 to the compressor refrigerant flow path 56 so that the temperature-regulated refrigerant is supplied from the cooler 50 to the compressor refrigerant flow path 56. The refrigerant recovery flow path 54 connects the cooler 50 to the compressor refrigerant flow path 56 in order to recover the refrigerant from the compressor refrigerant flow path 56 to the cooler 50. The cooler 50, the refrigerant supply flow path 52 and the refrigerant recovery flow path 54 in the cooling system 24 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 discharged gas flow path 38 and the compressor refrigerant flow path 56. The working gas flowing in the discharge gas flow path 38 is cooled by the refrigerant flowing in the compressor refrigerant flow path 56. Therefore, the refrigerant is heated in the second heat exchanger 44 and the heated refrigerant flows to the refrigerant recovery flow path 54. The temperature of the refrigerant flowing in the refrigerant recovery flow path 54 is higher than room temperature, for example, it is heated to a temperature from 50°C to 70°C. In addition, the working gas is cooled to an appropriate temperature in the second heat exchanger 44 and is supplied to the expander 18 through the discharge gas flow path 38 and the high-pressure pipe 32. In this way, the compression heat generated in the compressor body 36 is transferred 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 provided in the flushing gas line 22 so as to heat the flushing gas by using the exhaust heat of the compressor 20. The first heat exchanger 26 is configured to heat the flushing gas using a refrigerant heated by compression heat as a heat source. The first heat exchanger 26 is arranged outside the compressor 20. The first heat exchanger 26 may be provided in the compressor 20 adjacent to the outside of the compressor housing 42. The first heat exchanger 26 is configured to perform heat exchange in the refrigerant recovery flow path 54 and the flushing gas pipe 48. The flushing gas flowing in the flushing gas pipe 48 is heated by the refrigerant flowing in the refrigerant recovery flow path 54. The flushing gas sent from the flushing gas source 46 to the flushing gas pipe 48 is heated in the first heat exchanger 26, and the heated flushing gas is supplied to the cryopump housing 16 from the flushing valve 28. The temperature of the flushing gas supplied from the flushing gas line 22 to the cryopump housing 16 is higher than room temperature, for example, it is heated to a temperature from 40°C to 60°C. The refrigerant is cooled in the first heat exchanger 26 and returned to the cooler 50. In this way, the flushing gas is heated by the exhaust heat of the compressor 20 sent to the refrigerant. As the first heat exchanger 26, any applicable heat exchanger can be appropriately adopted. Similarly, as the second heat exchanger 44, any applicable heat exchanger can be appropriately adopted. The exhaust operation of the cryopump 10 is continued, whereby the gas gradually accumulates in the cryopump body 12. In order to discharge the accumulated gas to the outside, the cryopump body 12 is regenerated. When the regeneration ends, the exhaust operation can be restarted. When regeneration is started, the flushing gas is supplied to the cryopump housing 16 from the flushing gas line 22. The cryopump body 12 is heated by the reversal of the temperature rise of the expander 18 of the cryogenic refrigerator 14. The operation of the compressor 20 also continues during regeneration. 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 flushing gas is heated in the first heat exchanger 26 by the heated refrigerant. In this way, it is possible to use the exhaust heat of the compressor 20 to heat the flushing gas, and to supply the heated flushing gas to the cryopump housing 16. Since high-temperature flushing gas is supplied, the temperature rise of the cryopump main body 12 during regeneration can be accelerated. It is assumed that when the first heat exchanger 26 is not provided in the flushing gas line 22, the flushing gas at room temperature is supplied to the cryopump main body 12. On the other hand, according to the cryopump 10 of the first embodiment, compared with the case where the first heat exchanger 26 is not provided, it is possible to supply high-temperature flushing gas to the cryopump main body 12. Therefore, it is expected that the temperature of the cryopump main body 12 can be increased efficiently, thereby shortening the regeneration time. Furthermore, according to the cryopump 10 of the first embodiment, the exhaust heat of the compressor 20 that has been conventionally discarded to the outside can be utilized. Compared with other heating means such as an electric heater provided on the flushing gas pipeline 22, the cryopump 10 is superior in energy saving. Furthermore, according to the cryopump 10 of the first embodiment, the existing flushing gas line 22 can be directly used. No substantial modification of the flushing gas pipeline 22 is required. It is possible to minimize negative influences such as increase in installation space and increase in cost. (Second Embodiment) Fig. 2 schematically shows the cryopump 10 of the second embodiment. The illustrated cryopump 10 is different from the cryopump 10 shown in FIG. 1 in the structure of the first heat exchanger 26, and is substantially the same in other respects. Hereinafter, the description will focus on the different structures, but the same structure will be briefly described or the description will be 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 expander 18 is installed in the cryopump housing 16. The cryopump housing 16 is provided with a flushing valve 28 and a vent valve 30. In addition, the cryopump 10 includes a flushing gas line 22, a cooling system 24 and a first heat exchanger 26. The compressor 20 includes a compressor body 36, a discharge gas flow path 38, a suction gas flow path 40 and a compressor frame 42. The discharge gas flow path 38 connects the discharge port of the compressor body 36 to the high-pressure pipe 32, and the suction gas flow path 40 connects the suction port of the compressor body 36 to the low pressure pipe 34. Both the first heat exchanger 26 and the second heat exchanger 44 are provided on the compressor 20. The compressor housing 42 houses the compressor main body 36, the discharged gas flow path 38, the suction gas flow path 40, the first heat exchanger 26 and the second heat exchanger 44. The flushing gas pipeline 22 includes a flushing gas source 46 and a flushing gas pipe 48. The flushing gas pipe 48 includes a compressor flushing gas flow path 58 arranged in the compressor 20. The compressor flushing gas flow path 58 is housed in the compressor housing 42. The flushing gas is supplied to the flushing valve 28 from the flushing gas source 46 through the compressor flushing gas flow path 58 and the flushing gas pipe 48. The flushing gas is supplied to the cryopump housing 16 from the flushing valve 28. The cooling system 24 includes a cooler 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 provided in the flushing gas line 22 so as to heat the flushing gas by using the exhaust heat of the compressor 20. The first heat exchanger 26 is configured to heat the flushing gas using the working gas compressed by the compressor 20 as a heat source. The first heat exchanger 26 is configured to exchange heat in the discharge gas flow path 38 and the compressor flushing gas flow path 58. The flushing gas flowing in the compressor flushing gas flow path 58 is heated by the working gas flowing in the discharge gas flow path 38. The flushing gas sent from the flushing gas source 46 to the flushing gas pipe 48 is heated in the first heat exchanger 26, and the heated flushing gas is supplied to the cryopump housing 16 from the flushing valve 28. The working gas is cooled in 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 discharged gas flow path 38 and the compressor refrigerant flow path 56. The working gas flowing in the discharge gas flow path 38 is cooled by the refrigerant flowing in the compressor refrigerant flow path 56. Therefore, the refrigerant is heated in the second heat exchanger 44 and the heated refrigerant flows to the refrigerant recovery flow path 54. In addition, the working gas is cooled to an appropriate temperature in the second heat exchanger 44 and is 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 provided 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 body 36 and the second heat exchanger 44. The first heat exchanger 26 is provided directly downstream of the compressor body 36. Therefore, the first heat exchanger 26 can thermally contact the flushing gas and the higher temperature working gas. Therefore, the first heat exchanger 26 can heat the flushing gas to a higher temperature. In addition, due to the limitation of the heat-resistant temperature of the cryopump main body 12, etc., when it is desired to suppress excessive temperature rise of the flushing gas, the positional relationship between the first heat exchanger 26 and the second heat exchanger 44 may be reversed. In other words, 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 of the second embodiment, the flushing gas can be heated by the exhaust heat of the compressor 20 and the heated flushing gas can be supplied to the cryopump housing 16. The supply of high-temperature flushing gas can accelerate the temperature rise of the cryopump main body 12 during regeneration. Therefore, it is expected that the temperature of the cryopump main body 12 can be increased efficiently, thereby shortening the regeneration time. In addition, compared with other heating means such as an electric heater provided on the flushing gas pipeline 22, the cryopump 10 is superior in energy saving. Above, the present invention has been described based on the embodiments. Those having ordinary knowledge in the technical field can of course understand that the present invention is not limited to the above-mentioned embodiment, and various design changes can be made and various modifications are possible, and such modifications also belong to the scope of the present invention. In addition, one cryopump body 12 is shown in the drawing, but the cryopump 10 may include a plurality of cryopump bodies 12. In this case, the cryogenic refrigerator 14 includes at least one compressor 20 and a plurality of expanders 18. Each expander 18 is installed in the cryopump housing 16 of the corresponding cryopump body 12. A plurality of cryopump main bodies 12 can operate independently, for example, while regenerating one cryopump main body 12, the remaining cryopump main bodies 12 can continue the vacuum exhaust operation.

10‧‧‧Cryogenic Pump 14‧‧‧Very low temperature freezer 16‧‧‧Cryogenic pump housing 18‧‧‧Expander 20‧‧‧Compressor 22‧‧‧Flushing gas pipeline 24‧‧‧Cooling system 26‧‧‧The first heat exchanger

Fig. 1 schematically shows the cryopump of the first embodiment. Fig. 2 schematically shows the cryopump of the second embodiment.

10‧‧‧Cryogenic Pump

12‧‧‧Cryogenic pump body

14‧‧‧Very low temperature freezer

16‧‧‧Cryogenic pump housing

18‧‧‧Expander

19‧‧‧Motor

20‧‧‧Compressor

22‧‧‧Flushing gas pipeline

24‧‧‧Cooling system

26‧‧‧The first heat exchanger

28‧‧‧Flush valve

30‧‧‧Vent valve

32‧‧‧High pressure piping

34‧‧‧Low pressure piping

36‧‧‧Compressor body

38‧‧‧Exhaust gas flow path

40‧‧‧Inhalation gas flow path

42‧‧‧Compressor frame

44‧‧‧The second heat exchanger

46‧‧‧Flushing gas source

48‧‧‧Flushing gas piping

50‧‧‧Cooler

52‧‧‧Refrigerant supply flow path

54‧‧‧Refrigerant recovery flow path

56‧‧‧Compressor refrigerant flow path

Claims (2)

A cryopump is characterized by comprising: a cryopump housing; an extremely low temperature refrigerator including: an expander installed in the cryopump housing; and a compressor for recovering and compressing working gas from the expander, and The compressed working gas is supplied to the aforementioned expander; the flushing gas pipeline supplies the flushing gas to the aforementioned cryopump housing; and the heat exchanger is arranged in the aforementioned way to heat the flushing gas by using the exhaust heat of the compressor In the flushing gas line, the heat exchanger is configured to heat the flushing gas by using the working gas compressed by the compressor as a heat source. The cryopump described in claim 1 further includes a cooling system that uses a refrigerant to cool the compressor, so that the compression heat generated by the compression of the working gas in the compressor can be compressed from the compressor The heat exchanger is configured to use a refrigerant heated by the heat of compression as a heat source to heat the flushing gas.

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