WO2019163760A1

WO2019163760A1 - Cryopump

Info

Publication number: WO2019163760A1
Application number: PCT/JP2019/006063
Authority: WO
Inventors: 貴裕谷津
Original assignee: 住友重機械工業株式会社
Priority date: 2018-02-21
Filing date: 2019-02-19
Publication date: 2019-08-29
Also published as: JP2019143537A; KR20200123100A; US20200378378A1; TWI697621B; CN111712640A; TW201937061A

Abstract

A cryopump (10) is provided with: a cryopump housing (70); and a water-absorbing layer (80) attached to the exterior of the cryopump housing (70). The cryopump (10) may further be provided with a heat insulation layer (82) disposed between the cryopump housing (70) and the water-absorbing layer (80). The cryopump (10) may be provided with a water-absorbing heat insulation sheet (84) which includes the water-absorbing layer (80) on the outer side and the heat insulation layer (82) on the inner side.

Description

Cryopump

The present invention relates to a cryopump.

The cryopump is a vacuum pump that traps and exhausts gas molecules by condensation or adsorption on a cryopanel cooled to a cryogenic temperature. The cryopump is generally used to realize a clean vacuum environment required for a semiconductor circuit manufacturing process or the like. Since the cryopump is a so-called gas storage type vacuum pump, regeneration is required to periodically discharge the trapped gas to the outside.

Japanese Unexamined Patent Publication No. 60-71002

When the regeneration of the cryopump begins, the cryopump housing that houses the cryopanel is released from the vacuum. The gas is filled in the housing by re-vaporizing the accumulated gas or introducing purge gas. At the beginning of the reproduction, the cryopanels are still very cold. Since the vacuum insulation effect is lost by filling the gas, the housing can be cooled by the cryopanel through the gas. Since the housing is exposed to the surrounding environment, in some cases, condensation can occur on its outer surface. Condensed water can be dripped.

One of the exemplary purposes of an aspect of the present invention is to suppress condensation on the cryopump or to suppress dripping of condensed water.

According to an aspect of the present invention, the cryopump includes a cryopump housing and a water absorption layer attached to the outside of the cryopump housing.

It should be noted that any combination of the above-described constituent elements and the constituent elements and expressions of the present invention that are mutually replaced between methods, apparatuses, systems, etc. are also effective as an aspect of the present invention.

According to the present invention, condensation on the cryopump can be suppressed, or dripping of condensed water can be suppressed.

It is a sectional side view which shows roughly the cryopump which concerns on embodiment, and its dew condensation suppression structure. FIG. 2 is a cross-sectional view taken along line AA schematically showing the cryopump shown in FIG. It is the schematic which shows the other example of the dew condensation suppression structure which concerns on embodiment. It is the schematic which shows the other example of the dew condensation suppression structure which concerns on embodiment. It is the schematic which shows the other example of the dew condensation suppression structure which concerns on embodiment.

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 denoted by the same reference numerals, and redundant descriptions are omitted as appropriate. The scales and shapes of the respective parts shown in the drawings are set for convenience in order to facilitate explanation, and are not limitedly interpreted unless otherwise specified. The embodiments are illustrative and do not limit the scope of the present invention. All features and combinations thereof described in the embodiments are not necessarily essential to the invention.

FIG. 1 is a side sectional view schematically showing a cryopump 10 according to an embodiment. FIG. 2 is a cross-sectional view taken along line AA schematically showing the cryopump 10 shown in FIG. FIG. 1 shows a cross section including a cryopump central axis C indicated by a one-dot chain line. However, for easy understanding, the low-temperature cryopanel portion and the refrigerator of the cryopump 10 shown in FIG.

As will be described later, the cryopump 10 has a dew condensation suppression structure.

The cryopump 10 is attached to a vacuum chamber of, for example, an ion implantation apparatus, a sputtering apparatus, a vapor deposition apparatus, or other vacuum process apparatus to increase the degree of vacuum inside the vacuum chamber to a level required for a desired vacuum process. used. The cryopump 10 has an inlet 12 for receiving a gas to be evacuated from a vacuum chamber. Gas enters the internal space 14 of the cryopump 10 through the air inlet 12.

The cryopump 10 may be intended to be installed and used in a vacuum chamber with the orientation shown in the drawing, that is, the posture with the intake port 12 facing upward. However, the posture of the cryopump 10 is not limited thereto, and the cryopump 10 may be installed in the vacuum chamber in another direction.

In the following description, the terms “axial direction” and “radial direction” are sometimes used to express the positional relationship of the components of the cryopump 10 in an easy-to-understand manner. The axial direction represents the direction passing through the air inlet 12 (in FIG. 1, the direction along the cryopump central axis C passing through the center of the air inlet 12), and the radial direction is the direction along the air inlet 12 (the direction perpendicular to the central axis C). ). For convenience, the fact that it is relatively close to the inlet 12 in the axial direction may be referred to as “up”, and that it is relatively distant may be called “down”. In other words, the distance from the bottom of the cryopump 10 may be referred to as “up” and the distance from the bottom of the cryopump 10 as “lower”. Regarding the radial direction, the vicinity of the center of the inlet 12 (center axis C in FIG. 1) may be referred to as “inside” and the vicinity of the periphery of the inlet 12 may be referred to as “outer”. Such an expression is not related to the arrangement when the cryopump 10 is attached to the vacuum chamber. For example, the cryopump 10 may be attached to the vacuum chamber with the inlet 12 facing downward in the vertical direction.

Also, the direction surrounding the axial direction may be called “circumferential direction”. The circumferential direction is a second direction along the air inlet 12 and is a tangential direction orthogonal to the radial direction.

The cryopump 10 includes a refrigerator 16, a first stage cryopanel 18, a second stage cryopanel assembly 20, and a cryopump housing 70. The first stage cryopanel 18 can also be referred to as a high temperature cryopanel section or a 100K section. The second stage cryopanel assembly 20 can also be referred to as a low temperature cryopanel section or a 10K section.

The refrigerator 16 is a cryogenic refrigerator such as a Gifford-McMahon refrigerator (so-called GM refrigerator). The refrigerator 16 is a two-stage refrigerator. Therefore, the refrigerator 16 includes a first cooling stage 22 and a second cooling stage 24. The refrigerator 16 is configured to cool the first cooling stage 22 to the first cooling temperature and to cool the second cooling stage 24 to the second cooling temperature. The second cooling temperature is lower than the first cooling temperature. For example, the first cooling stage 22 is cooled to about 65K to 120K, preferably 80K to 100K, and the second cooling stage 24 is cooled to about 10K to 20K.

The refrigerator 16 also includes a refrigerator structure portion 21 that structurally supports the second cooling stage 24 on the first cooling stage 22 and structurally supports the first cooling stage 22 on the room temperature portion 26 of the refrigerator 16. Prepare. Therefore, the refrigerator structure unit 21 includes a first cylinder 23 and a second cylinder 25 that extend coaxially along the radial direction. The first cylinder 23 connects the room temperature part 26 of the refrigerator 16 to the first cooling stage 22. The second cylinder 25 connects the first cooling stage 22 to the second cooling stage 24. The room temperature section 26, the first cylinder 23, the first cooling stage 22, the second cylinder 25, and the second cooling stage 24 are arranged in a straight line in this order.

In each of the first cylinder 23 and the second cylinder 25, a first displacer and a second displacer (not shown) are disposed so as to be able to reciprocate. A first regenerator and a second regenerator (not shown) are incorporated in the first displacer and the second displacer, respectively. The room temperature section 26 has a drive mechanism (not shown) for reciprocating the first displacer and the second displacer. The drive mechanism includes a flow path switching mechanism that switches the flow path of the working gas so that the supply and discharge of the working gas (for example, helium) to the inside of the refrigerator 16 are periodically repeated.

The first cooling stage 22 is installed at the first stage low temperature end of the refrigerator 16. The first cooling stage 22 is a member that encloses the end of the first cylinder 23 on the side opposite to the room temperature portion 26 and surrounds the first expansion space of the working gas. The first expansion space is a variable volume that is formed between the first cylinder 23 and the first displacer inside the first cylinder 23 and whose volume changes with the reciprocation of the first displacer. The first cooling stage 22 is made of a metal material having a higher thermal conductivity than the first cylinder 23. For example, the first cooling stage 22 is made of copper, and the first cylinder 23 is made of stainless steel.

The second cooling stage 24 is installed at the second stage low temperature end of the refrigerator 16. The second cooling stage 24 is a member that encloses the end portion of the second cylinder 25 on the side opposite to the room temperature portion 26 and surrounds the second expansion space of the working gas. The second expansion space is a variable volume that is formed between the second cylinder 25 and the second displacer inside the second cylinder 25 and has a volume that changes as the second displacer reciprocates. The second cooling stage 24 is made of a metal material having a higher thermal conductivity than the second cylinder 25. The second cooling stage 24 is made of copper, and the second cylinder 25 is made of stainless steel. In FIG. 1, a boundary 24b between the second cooling stage 24 and the second cylinder 25 is shown.

The refrigerator 16 is connected to a working gas compressor (not shown). The refrigerator 16 expands the working gas pressurized by the compressor to cool the first cooling stage 22 and the second cooling stage 24. The expanded working gas is collected in the compressor and pressurized again. The refrigerator 16 generates cold by repeating a heat cycle including supply and discharge of the working gas and reciprocation of the first displacer and the second displacer in synchronization therewith.

The illustrated cryopump 10 is a so-called horizontal cryopump. The horizontal type cryopump is generally a cryopump in which the refrigerator 16 is disposed so as to intersect (usually orthogonal) the central axis C of the cryopump 10. The first cooling stage 22 and the second cooling stage 24 of the refrigerator 16 are arranged in a direction perpendicular to the cryopump center axis C (the horizontal direction in FIG. 1 and the direction of the center axis D of the refrigerator 16). .

The first stage cryopanel 18 includes a radiation shield 30 and an entrance cryopanel 32 and surrounds the second stage cryopanel assembly 20. The first stage cryopanel 18 is a cryopanel provided to protect the second stage cryopanel assembly 20 from radiant heat from the outside of the cryopump 10 or from the cryopump housing 70. The first stage cryopanel 18 is thermally coupled to the first cooling stage 22. Therefore, the first stage cryopanel 18 is cooled to the first cooling temperature. The first stage cryopanel 18 has a gap with the second stage cryopanel assembly 20, and the first stage cryopanel 18 is not in contact with the second stage cryopanel assembly 20.

The radiation shield 30 is provided to protect the second stage cryopanel assembly 20 from the radiant heat of the cryopump housing 70. The radiation shield 30 is located between the cryopump housing 70 and the second stage cryopanel assembly 20 and surrounds the second stage cryopanel assembly 20. The radiation shield 30 has a shield main opening 34 for receiving gas from the outside of the cryopump 10 into the internal space 14. The shield main opening 34 is located at the air inlet 12.

The radiation shield 30 includes a shield front end 36 that defines the shield main opening 34, a shield bottom 38 that is located on the opposite side of the shield main opening 34, and a shield side 40 that connects the shield front end 36 to the shield bottom 38. The shield front end 36 forms a part of the shield side portion 40. The shield side portion 40 extends in the axial direction from the shield front end 36 to the side opposite to the shield main opening 34, and extends in the circumferential direction so as to surround the second cooling stage 24. The radiation shield 30 has a cylindrical shape (for example, a cylinder) in which the shield bottom 38 is closed, and is formed in a cup shape. An annular gap 42 is formed between the shield side portion 40 and the second stage cryopanel assembly 20.

The shield bottom portion 38 may be a separate member from the shield side portion 40. For example, the shield bottom portion 38 may be a flat disk having substantially the same diameter as the shield side portion 40, and may be attached to the shield side portion 40 on the side opposite to the shield main opening 34. Further, at least a part of the shield bottom 38 may be opened. For example, the radiation shield 30 may not be blocked by the shield bottom 38. That is, both ends of the shield side part 40 may be open.

The shield side part 40 has a shield side part opening 44 into which the refrigerator structure part 21 is inserted. The second cooling stage 24 and the second cylinder 25 are inserted into the radiation shield 30 from outside the radiation shield 30 through the shield side opening 44. The shield side part opening 44 is an attachment hole formed in the shield side part 40, and is circular, for example. The first cooling stage 22 is disposed outside the radiation shield 30.

The shield side portion 40 includes a mounting seat 46 for the refrigerator 16. The mounting seat 46 is a flat portion for mounting the first cooling stage 22 to the radiation shield 30 and is slightly recessed when viewed from the outside of the radiation shield 30. The mounting seat 46 forms the outer periphery of the shield side opening 44. The mounting seat 46 is closer to the shield bottom 38 than the shield front end 36 in the axial direction. The radiation shield 30 is thermally coupled to the first cooling stage 22 by attaching the first cooling stage 22 to the mounting seat 46.

The inlet cryopanel 32 is provided in the shield main opening 34 in order to protect the second-stage cryopanel assembly 20 from radiant heat from a heat source outside the cryopump 10. The heat source outside the cryopump 10 is, for example, a heat source in a vacuum chamber to which the cryopump 10 is attached. The inlet cryopanel 32 can limit not only radiant heat but also the ingress of gas molecules. The inlet cryopanel 32 occupies a part of the opening area of the shield main opening 34 so as to limit the gas flow into the internal space 14 through the shield main opening 34 to a desired amount. An annular open region 48 is formed between the inlet cryopanel 32 and the shield front end 36.

The inlet cryopanel 32 is attached to the shield front end 36 by an appropriate attachment member and is thermally coupled to the radiation shield 30. The inlet cryopanel 32 is thermally coupled to the first cooling stage 22 via the radiation shield 30. The entrance cryopanel 32 has, for example, a plurality of annular or linear slats. Alternatively, the inlet cryopanel 32 may be a single plate-like member.

The second stage cryopanel assembly 20 is attached to the second cooling stage 24 so as to surround the second cooling stage 24. Therefore, the second stage cryopanel assembly 20 is thermally coupled to the second cooling stage 24, and the second stage cryopanel assembly 20 is cooled to the second cooling temperature. The second stage cryopanel assembly 20 is surrounded by the shield side portion 40 together with the second cooling stage 24.

The second-stage cryopanel assembly 20 includes a top cryopanel 60 facing the shield main opening 34, a plurality (two in this example) of cryopanel members 62, and a cryopanel mounting member 64.

Further, as shown in FIG. 1, the cryopump 10 includes a cryopanel positioning member 67. The heat transfer section that thermally couples the second stage cryopanel assembly 20 to the second cooling stage 24 includes a cryopanel mounting member 64 and a cryopanel positioning member 67. The top cryopanel 60 and the cryopanel member 62 are attached to the second cooling stage 24 via a cryopanel attachment member 64 and a cryopanel positioning member 67.

Since the annular gap 42 is formed between the top cryopanel 60 and the cryopanel member 62 and the shield side portion 40, both the top cryopanel 60 and the cryopanel member 62 are not in contact with the radiation shield 30. The cryopanel member 62 is covered with a top cryopanel 60.

The top cryopanel 60 is the portion of the second stage cryopanel assembly 20 that is closest to the inlet cryopanel 32. The top cryopanel 60 is disposed between the shield main opening 34 or the inlet cryopanel 32 and the refrigerator 16 in the axial direction. The top cryopanel 60 is located at the center of the internal space 14 of the cryopump 10 in the axial direction. Therefore, a main storage space 65 for the condensed layer is widely formed between the front surface of the top cryopanel 60 and the inlet cryopanel 32. The main storage space 65 of the condensed layer occupies the upper half of the internal space 14.

The top cryopanel 60 is a substantially flat cryopanel arranged perpendicular to the axial direction. That is, the top cryopanel 60 extends in the radial direction and the circumferential direction. As shown in FIG. 2, the top cryopanel 60 is a disk-like panel having a size (for example, a projected area) larger than the entrance cryopanel 32. However, the relationship between the dimensions of the top cryopanel 60 and the entrance cryopanel 32 is not limited to this, and the top cryopanel 60 may be smaller, or both may have substantially the same dimensions.

The top cryopanel 60 is disposed so as to form a gap region 66 between the top cryopanel 60 and the refrigerator structure portion 21. The gap region 66 is a space formed in the axial direction between the back surface of the top cryopanel 60 and the second cylinder 25.

The cryopanel member 62 is provided with an adsorbent 74 such as activated carbon. For example, the adsorbent 74 is bonded to the back surface of the cryopanel member 62. The front surface of the cryopanel member 62 is intended to function as a condensing surface and the back surface as an adsorption surface. An adsorbent 74 may be provided on the front surface of the cryopanel member 62. Similarly, the top cryopanel 60 may have an adsorbent 74 on the front surface and / or back surface thereof. Alternatively, the top cryopanel 60 may not include the adsorbent 74.

The two cryopanel members 62 are disposed on both sides of the second cooling stage 24 with the cryopump central axis C interposed therebetween. The cryopanel member 62 is disposed along a plane perpendicular to the center axis C of the cryopump. For ease of understanding, the cryopanel member 62 and the cryopanel mounting member 64 are shown by broken lines in FIG.

The two cryopanel members 62 are arranged at a height position between the upper end and the lower end of the second cooling stage 24 in the direction of the cryopump central axis C. The two cryopanel members 62 are arranged at the same height. The second cooling stage 24 includes a flange portion 24a at the end in a direction perpendicular to the cryopump central axis C (the direction of the central axis D of the refrigerator 16). An upper end and a lower end of the second cooling stage 24 in the direction of the cryopump central axis C are defined by a flange portion 24a. That is, the two cryopanel members 62 are arranged at a height position between the upper end and the lower end of the flange portion 24a of the second cooling stage 24 in the direction of the cryopump central axis C.

The two cryopanel members 62 are designed as the same part. The two cryopanel members 62 have the same shape and are formed of the same material. The cryopanel member 62 has a bow shape, a semimoon shape, or a semicircular shape. The cryopanel member 62 is formed of a metal material having a high thermal conductivity such as copper, and may be covered with a plating layer such as nickel.

As shown in FIG. 2, the cryopanel member 62 includes an arc portion 78 and a string 79. When viewed in the direction of the cryopump central axis C, the two cryopanel members 62 are arranged symmetrically with respect to an intermediate line between them (the central axis D of the refrigerator 16). The arc portions 78 of the two cryopanel members 62 are on the same circumference around the cryopump central axis C. Each cryopanel member 62 has a line-symmetric shape with a line E passing through the midpoint of the string 79 (or the cryopump central axis C) and perpendicular to the string 79 as an axis of symmetry.

As shown in FIG. 1, the cryopanel positioning member 67 is fixed to the flange portion 24 a of the second cooling stage 24 and supported by the second cooling stage 24. The cryopanel positioning member 67 is formed in an inverted L shape that is inverted upside down. By using the cryopanel positioning member 67, restrictions on the length of the refrigerator 16 in the direction of the central axis D are relaxed. Even if the flange portion 24a of the second cooling stage 24 is at a position deviated from the cryopump center axis C in the direction of the center axis D of the refrigerator 16, the length of the upper side portion 67a of the cryopanel positioning member 67 is adjusted. Thus, the second stage cryopanel assembly 20 can be positioned on the cryopump central axis C. As a result, an existing refrigerator can be employed in place of the refrigerator designed exclusively for the cryopump 10. This can be useful for reducing the manufacturing cost of the cryopump 10.

In order to align the second stage cryopanel assembly 20 with respect to the center axis C of the cryopump, the upper side portion 67a of the cryopanel positioning member 67 is opposite to that shown in FIG. You may extend so that it may leave | separate from the 2nd cylinder 25 in the direction of the central axis D of the refrigerator 16 from the flange part 24a. For the cryopump 10 having the large-diameter inlet 12, the cryopanel positioning member 67 having such a shape may be suitable.

The cryopump 10 includes a gas flow adjusting member 50 configured to deflect the flow of gas flowing in from the shield main opening 34 from the refrigerator structure unit 21. The gas flow adjusting member 50 is configured to deflect the gas flow flowing into the main accommodating space 65 through the inlet cryopanel 32 or the open region 48 from the second cylinder 25. The gas flow adjusting member 50 may be a gas flow deflecting member or a gas flow reflecting member disposed adjacent to and above the refrigerator structure 21 or the second cylinder 25. The gas flow adjusting member 50 is locally provided at the same position as the shield side opening 44 in the circumferential direction. The gas flow adjusting member 50 has a rectangular shape when viewed from above. The gas flow adjusting member 50 is, for example, a single flat plate, but may be curved.

The gas flow adjusting member 50 extends from the shield side 40 and is inserted into the gap region 66. However, the gas flow adjusting member 50 is not in contact with the portion of the second cooling temperature surrounding the top cryopanel 60, the second cylinder 25, and the gap region 66. The gas flow adjusting member 50 is thermally coupled to the first cooling stage 22 via the radiation shield 30. Therefore, the gas flow adjusting member 50 is cooled to the first cooling temperature.

The cryopump housing 70 is a housing of the cryopump 10 that houses the first-stage cryopanel 18, the second-stage cryopanel assembly 20, and the refrigerator 16, and is configured to maintain the vacuum airtightness of the internal space 14. Vacuum container. The cryopump housing 70 includes the first stage cryopanel 18 and the refrigerator structure 21 in a non-contact manner. The cryopump housing 70 is attached to the room temperature portion 26 of the refrigerator 16.

The inlet 12 is defined by the front end of the cryopump housing 70. The cryopump housing 70 includes an inlet flange 72 that extends radially outward from its front end. The inlet flange 72 is provided over the entire circumference of the cryopump housing 70. The cryopump 10 is attached to a vacuum chamber to be evacuated using an intake port flange 72.

The cryopump housing 70 includes a cryopanel housing portion 76 that surrounds the radiation shield 30 in a non-contact manner with the radiation shield 30, and a refrigerator housing portion 77 that surrounds the first cylinder 23 of the refrigerator 16. The cryopanel housing portion 76 and the refrigerator housing portion 77 are integrally formed.

The cryopanel housing portion 76 has a cylindrical or dome shape in which an inlet flange 72 is formed at one end and the other end is closed as a housing bottom surface 70a. In addition to the air inlet 12, an opening through which the refrigerator 16 is inserted is formed on the side wall of the cryopanel housing portion 76 that connects the air inlet flange 72 to the housing bottom surface 70 a. The refrigerator accommodating portion 77 has a cylindrical shape extending from the opening to the room temperature portion 26 of the refrigerator 16. The refrigerator housing unit 77 connects the cryopanel housing unit 76 to the room temperature unit 26 of the refrigerator 16.

The cryopump 10 includes a water absorption layer 80 mounted on the outside of the cryopump housing 70, and a heat insulating layer 82 disposed between the cryopump housing 70 and the water absorption layer 80. A dew condensation suppressing structure of the cryopump 10 is formed by the water absorption layer 80 and the heat insulating layer 82. The dew condensation suppressing structure includes a water absorbing and heat insulating sheet 84 having a water absorbing layer 80 on the outside and a heat insulating layer 82 on the inside. The water absorbing heat insulating sheet 84 is configured as a sheet in which the water absorbing layer 80 is bonded to the outside of the heat insulating layer 82.

The water-absorbing heat insulating sheet 84 covers at least a part of the outer surface of the cryopump housing 70, for example, the entire surface. The water-absorbing heat insulating sheet 84 is attached to both the cryopanel housing portion 76 and the refrigerator housing portion 77 and covers almost the entire surface thereof. The water-absorbing heat insulating sheet 84 is wound around the side surface of the cryopanel housing portion 76 and covers the side surface. Moreover, the water absorption heat insulation sheet 84 is also attached to the housing bottom face 76a. The water absorption heat insulating sheet 84 is also wound around the refrigerator housing portion 77. The water-absorbing heat insulating sheet 84 is attached to the cryopump housing 70 using an appropriate bonding method.

However, the intake port flange 72 is not covered with the water absorption heat insulating sheet 84. In most cases, condensation does not occur even if the inlet flange 72 is exposed, so that it is not necessary to attach the water absorbing layer 80 and / or the heat insulating layer 82 to the inlet flange 72. If necessary, the water absorption layer 80 and / or the heat insulation layer 82 may be attached to the intake port flange 72.

The water absorbing layer 80 is a material that is superior in water absorption compared to a structural material (for example, stainless steel such as SUS304) that forms the outer surface of the cryopump housing 70 and / or a heat insulating material that forms the heat insulating layer 82. It is formed with. The water-absorbing layer 80 is formed of, for example, a water-absorbing material that adsorbs moisture chemically and / or physically such as a water-absorbing resin or a water-absorbing porous material, or a material containing such a water-absorbing material. The water absorption layer 80 can employ | adopt suitably the goods marketed by common names, such as a water absorbing resin, a water absorbing polymer, and a water absorbing sheet. Or the water absorption layer 80 may be formed with the material which hold | maintains water | moisture content at least temporarily, such as felt and sponge.

The heat insulating layer 82 is made of a material having a lower thermal conductivity than the structural material forming the outer surface of the cryopump housing 70. The heat insulating layer 82 may be formed of various known heat insulating materials such as a foam heat insulating material and / or a fiber heat insulating material.

The thickness 86 of the heat insulating layer 82 is determined so that the temperature of the water absorbing layer 80 is maintained at a temperature higher than 0 ° C. during the regeneration of the cryopump 10. The thickness 86 of the heat insulating layer 82 may be determined such that the temperature of the water absorbing layer 80 is maintained at a temperature higher than 5 ° C or higher than 10 ° C. In other words, the thickness 86 of the heat insulating layer 82 is determined so that the temperature of the outer surface of the heat insulating layer 82 does not fall below the freezing point of water during the regeneration of the cryopump 10.

The operation of the cryopump 10 configured as described above will be described below. When the cryopump 10 is operated, the vacuum chamber is first roughed to about 1 Pa with another appropriate roughing pump before the operation. Thereafter, the cryopump 10 is operated. The first cooling stage 22 and the second cooling stage 24 are cooled to the first cooling temperature and the second cooling temperature, respectively, by driving the refrigerator 16. Therefore, the first-stage cryopanel 18 and the second-stage cryopanel assembly 20 that are thermally coupled to these are also cooled to the first cooling temperature and the second cooling temperature, respectively.

The inlet cryopanel 32 cools the gas flying from the vacuum chamber toward the cryopump 10. A gas having a sufficiently low vapor pressure (for example, 10 ⁻⁸ Pa or less) condenses on the surface of the inlet cryopanel 32 at the first cooling temperature. This gas may be referred to as a first type gas (also referred to as type 1 gas). The first type gas is, for example, water vapor. Thus, the inlet cryopanel 32 can exhaust the first type gas. A part of the gas whose vapor pressure is not sufficiently low at the first cooling temperature passes through the inlet cryopanel 32 or the open region 48 and enters the main accommodating space 65. Alternatively, the other part of the gas is reflected by the inlet cryopanel 32 and does not enter the main accommodating space 65.

The gas that has entered the main housing space 65 is cooled by the second-stage cryopanel assembly 20. A gas having a sufficiently low vapor pressure (for example, 10 ⁻⁸ Pa or less) is condensed on the surface of the second stage cryopanel assembly 20 at the second cooling temperature. This gas may be referred to as a second type gas (also referred to as type 2 gas). The second type gas is, for example, nitrogen or argon. Thus, the second stage cryopanel assembly 20 can exhaust the second type gas. Since it faces the main housing space 65 directly, a condensed layer of the second type gas can grow greatly on the front surface of the top cryopanel 60. The second type gas is a gas that does not condense at the first cooling temperature.

The gas whose vapor pressure is not sufficiently low at the second cooling temperature is adsorbed by the adsorbent 74 of the second stage cryopanel assembly 20. This gas may be referred to as a third type gas (also referred to as type 3 gas). The third type gas is, for example, hydrogen. Thus, the second stage cryopanel assembly 20 can exhaust the third type gas. Therefore, the cryopump 10 can exhaust various gases by condensation or adsorption, and can reach the desired vacuum level of the vacuum chamber.

The gas is accumulated in the cryopump 10 by continuing the exhaust operation. In order to discharge the accumulated gas to the outside, the cryopump 10 is regenerated. When the regeneration is completed, the exhaust operation can be started again.

In order to accelerate the temperature rise of the cryopump 10 and shorten the regeneration time, generally, purge gas is introduced into the cryopump housing 70 at the start of regeneration. The cryopump housing 70 is filled with the gas due to the re-vaporization of the purge gas or the stored gas, so that the vacuum heat insulating effect is lost unlike during the exhaust operation. Heat exchange between the cryopanel and the cryopump housing 70 is promoted through the gas. Immediately after the start of reproduction, the cryopump housing 70 can be cooled because the cryopanel is still cooled to an extremely low temperature.

Further, since the cryopump 10 has a large main accommodating space 65, a large amount of the second type gas can be stored. The second type gas dissolves into a liquid at a relatively early stage of regeneration. As described above, since the second type gas is nitrogen or argon, this liquefied gas is very cold. The liquefied gas can flow down to the bottom of the radiation shield 30 or the cryopump housing 70 and contact the inner surface of the cryopump housing 70. As a result, the cryopump housing 70 is significantly cooled. Therefore, moisture in the surrounding air may be condensed on the outer surface of the cryopump housing 70 or frost may be attached. During regeneration, the cryopump 10 is gradually heated to room temperature, so that frost will eventually melt. If a large amount of frost is attached, it melts into a large amount of water and can be dripped. Other devices and articles around the cryopump 10 or the floor may be wetted.

The cryopump 10 according to the embodiment includes a water absorption layer 80 attached to the outside of the cryopump housing 70. Moisture that tends to adhere to the outer surface of the cryopump housing 70 is absorbed by the water absorption layer 80. Therefore, condensation on the cryopump 10 can be suppressed. Since condensation is suppressed, dripping of water around the cryopump 10 and the floor surface is also suppressed.

Further, the heat insulating layer 82 is disposed between the cryopump housing 70 and the water absorbing layer 80. Compared with the temperature drop of the cryopump housing 70, the temperature drop of the outer surface of the heat insulation layer 82 is small. The temperature difference between the outside air temperature and the water absorbing layer 80 can be reduced as compared with the case where the water absorbing layer 80 is directly attached to the cryopump housing 70 without the heat insulating layer 82. Therefore, condensation on the cryopump 10 can be suppressed.

If the outer surface temperature of the heat insulating layer 82 is below room temperature, condensation may occur. In order to prevent dew condensation only by the heat insulating layer 82 without providing the water absorbing layer 80, the thickness 86 of the heat insulating layer 82 must be sufficiently thick. In this case, the required thickness 86 of the heat insulating layer 82 may become so large that it is difficult to actually mount the cryopump housing 70.

However, since the cryopump 10 according to the embodiment includes the water absorption layer 80, it can absorb moisture that can be condensed on the outer surface of the heat insulation layer 82. The outer surface of the heat insulating layer 82 may be cooled to some extent from room temperature, and the heat insulating layer 82 can be made thin. It is expected that the water absorption layer 80 itself does not need that much thickness. Therefore, by combining the water absorption layer 80 and the heat insulating layer 82, a dew condensation suppressing structure having a small thickness as a whole can be realized, and mounting on the cryopump 10 becomes easier.

In some typical conventional cryopumps, an electric heater such as a band heater is wound around a housing in order to suppress condensation. The cryopump 10 according to the embodiment also has an advantage of not requiring such an electric heater (therefore, the cryopump 10 according to the embodiment does not have an electric heater for heating the cryopump housing 70).

Also, the cryopump 10 according to the embodiment does not require a water receiving tray called a drain pan.

The cryopump 10 includes a water absorbing and heat insulating sheet 84 having a water absorbing layer 80 on the outside and a heat insulating layer 82 on the inside. When the water absorbing layer 80 and the heat insulating layer 82 are separate layers, a two-step operation is required such that the heat insulating layer 82 is first attached to the cryopump housing 70 and the water absorbing layer 80 is attached to the heat insulating layer 82. Become. In the case of the water-absorbing heat insulating sheet 84, the water-absorbing layer 80 and the heat-insulating layer 82 can be mounted together on the cryopump housing 70, so that the manufacture becomes easy.

If the outer surface temperature of the water-absorbing layer 80 is lower than 0 ° C., moisture that is condensed can freeze on the outer surface of the water-absorbing layer 80. An ice layer separates from the water absorption layer 80 and adheres onto the water absorption layer 80. When the ice layer melts due to the temperature rise of the cryopump 10, water may be dripped. However, according to the embodiment, the thickness 86 of the heat insulating layer 82 is determined such that the temperature of the water absorbing layer 80 is maintained at a temperature higher than 0 ° C. during the regeneration of the cryopump 10. Therefore, formation of an ice layer on the water absorption layer 80 is suppressed, and dripping of water is also suppressed.

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

In the above-described embodiment, the water-absorbing and heat-insulating sheet 84 is attached to both the cryopanel housing portion 76 and the refrigerator housing portion 77, but this is not essential. The water absorption layer 80, the heat insulation layer 82, and / or the water absorption heat insulation sheet 84 may be attached to only one of the cryopanel accommodation portion 76 and the refrigerator accommodation portion 77.

The water absorption layer 80, the heat insulation layer 82, and / or the water absorption heat insulation sheet 84 may be attached to the cryopump housing 70 so as to cover only a part of the outer surface of the cryopump housing 70. For example, the water-absorbing heat insulating sheet 84 may be attached only to the lower part of the cryopanel housing portion 76. If it does in this way, the dew condensation which flows down from the upper part of the cryopanel accommodating part 76 is absorbed with the water absorption heat insulation sheet | seat 84, and dripping of a dew condensation can be suppressed. Further, the refrigerator accommodating portion 77 may be provided with components such as valves and sensors that protrude outward from the cylindrical portion. Such a component does not need to be covered with the water absorption heat insulation sheet 84.

The water absorbing layer 80 may be disposed between the cryopump housing 70 and the heat insulating layer 82. That is, the water absorption layer 80 may be disposed inside the heat insulation layer 82. For example, as shown in FIG. 3, the cryopump housing 70 may have corners or curved portions. In order to provide good thermal insulation, the thickness 86 of the thermal insulation layer 82 is relatively large. Therefore, it is assumed that the heat insulating layer 82 is hardly adhered to the corner portion or the curved portion and is difficult to cover completely. In such a case, the corners or curved portions of the cryopump housing 70 may be covered with a water absorption layer 80 as shown in the drawing.

In addition, as shown in FIG. 4, when the heat insulating layer 82 is difficult to completely cover the corner portion or the curved portion of the cryopump housing 70, the water absorbing layer 80 may cover the heat insulating layer 82 from the outside. In this case, since the heat insulating layer 82 is not provided at the corner or the curved portion of the cryopump housing 70, a gap 87 may be formed between the corner or the curved portion and the water absorption layer 80.

As shown in FIG. 5, the cryopump 10 may include a drain pan 88. The drain pan 88 is provided as a water receiving tray disposed below the cryopump housing 70, and is configured to prevent the condensed water from dripping onto the floor surface 94 and / or to receive and store the condensed water dropped. Has been. The drain pan 88 is attached to the cryopanel housing portion 76 of the cryopump housing 70. The drain pan 88 may be fastened together with the caster 90 in the cryopanel housing portion 76. A heat insulating spacer 92 may be inserted between the drain pan 88 and the cryopanel accommodating portion 76. The drain pan 88 may be attached to the cryopump housing 70 by other methods such as being suspended from the intake port flange 72.

The water absorption layer 80, the heat insulation layer 82, and / or the water absorption heat insulation sheet 84 are attached to the refrigerator housing portion 77. The water absorption layer 80, the heat insulation layer 82, and / or the water absorption heat insulation sheet 84 may be attached to the cryopanel housing portion 76. Thus, the drain pan 88 may be used in combination with the dew condensation suppressing structure according to the embodiment.

In the above description, a horizontal cryopump is illustrated, but the present invention can also be applied to other vertical cryopumps. The vertical cryopump refers to a cryopump in which the refrigerator 16 is disposed along the cryopump central axis C of the cryopump 10. In that case, the refrigerator housing portion 77 is installed not on the side surface of the cryopanel housing portion 76 but on the housing bottom surface 76a. Further, the internal configuration of the cryopump, such as the arrangement, shape, and number of cryopanels, is not limited to the specific embodiment described above. Various known configurations can be employed as appropriate.

10 cryopump, 70 cryopump housing, 80 water absorption layer, 82 heat insulation layer, 84 water absorption heat insulation sheet.

The present invention can be used in the field of cryopumps.

Claims

A cryopump housing;
A cryopump comprising: a water absorption layer mounted on the outside of the cryopump housing.
The cryopump according to claim 1, further comprising a heat insulating layer disposed between the cryopump housing and the water absorption layer.
The cryopump according to claim 2, further comprising a water-absorbing and heat-insulating sheet having the water-absorbing layer on the outside and the heat-insulating layer on the inside.
4. The cryo of claim 2, wherein the thickness of the heat insulating layer is determined such that the temperature of the water absorbing layer is maintained at a temperature higher than 0 ° C. during regeneration of the cryopump. pump.