WO2018164011A1

WO2018164011A1 - Cryopump

Info

Publication number: WO2018164011A1
Application number: PCT/JP2018/008132
Authority: WO
Inventors: 誠下村
Original assignee: 住友重機械工業株式会社
Priority date: 2017-03-10
Filing date: 2018-03-02
Publication date: 2018-09-13
Also published as: CN110352301B; JP6762672B2; CN110352301A; TWI655365B; JP2018150846A; TW201833439A

Abstract

The cryopump 10 is provided with: a freezer 16 comprising a room-temperature part, a first cooling stage, and a second cooling stage; and a cryopump housing 70 comprising a radiation shield thermally coupled to the first cooling stage and surrounding the second cooling stage without making contact with the second cooling stage, a shield housing part 74 which has an intake port 12 and a housing bottom surface 70a disposed on the opposite side from the intake port 12 and which surrounds the radiation shield without making contact with the radiation shield, and a freezer housing part 76 which connects the shield housing part 74 to the room-temperature part 26 of the freezer 16. A first heater 84 disposed on an outer surface of the freezer housing part 76, or a second heater disposed on the housing bottom surface 70a, or a heat transfer member thermally coupled to the first cooling stage and disposed in a gap between the freezer housing part 76 and the freezer 16 is provided so as to apply heat into the cryopump housing 70 from the outside.

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. For regeneration, the cryopump is heated from cryogenic temperature to room temperature or somewhat higher. For this purpose, a cryopump is usually provided with a heat source such as an electric heater attached to a cooling source such as a cooling stage of a refrigerator. In addition, the refrigerator itself may allow a heating operation with a thermodynamic temperature increase cycle (including adiabatic compression of working gas) instead of the refrigeration cycle. The ice trapped on the cryopanel melts by heating and eventually vaporizes and is discharged out of the cryopump.

Japanese Patent No. 2,725,689

As a result of intensive studies on the regeneration of cryopumps, the present inventors have recognized the following problems. Various gases other than water trapped by the cryopump easily evaporate at a regeneration temperature of the room temperature level, and thus are easily discharged from the cryopump. However, water takes a liquid state in that temperature range. Liquid water flows downward in accordance with gravity and collects at the bottom of the cryopump or elsewhere. The outlet is not always at the bottom. In order to drain the water accumulated below the outlet, the water must be evaporated. When water evaporates, it takes heat away from the surroundings. As the amount of accumulated water increases, the amount of heat absorbed by evaporation also increases, and in some cases, the water surface can freeze.
In particular, a large-capacity cryopump designed to exhaust a large amount of water is prone to freezing because of its large volume. Evaporation of water is remarkably suppressed along with icing, making it difficult to discharge by vaporization, resulting in a long regeneration time. There is a possibility that the reproduction is not completed within a practically acceptable time. Therefore, it is desirable to discharge water more efficiently in order to shorten the regeneration time.

One exemplary purpose of one aspect of the present invention is to reduce the regeneration time of the cryopump.

According to an aspect of the present invention, the cryopump includes a refrigerator having a room temperature portion, a first cooling stage, and a second cooling stage, and is thermally coupled to the first cooling stage, and is not connected to the second cooling stage. A shield housing that has a radiation shield surrounding the second cooling stage in contact and a cryopump inlet, and has a housing bottom on the opposite side of the cryopump inlet, and surrounds the radiation shield in non-contact with the radiation shield A cryopump housing comprising: a refrigerator housing unit that connects the shield housing unit to the room temperature unit of the refrigerator; and an outer surface of the refrigerator housing unit that applies heat to the inside from the outside of the cryopump housing. Or a heater disposed on the bottom surface of the housing.

According to an aspect of the present invention, the cryopump is a refrigerator having a room temperature section, a first cooling stage, and a second cooling stage, and is thermally coupled to the first cooling stage and surrounds the second cooling stage. A radiation shield and a cryopump inlet; a housing bottom surface on the opposite side of the cryopump inlet; a shield housing portion that surrounds the radiation shield in a non-contact manner with the radiation shield; and A cryopump housing provided with a refrigerator housing portion connected to the room temperature portion of the machine, and a heat pump thermally coupled to the first cooling stage and disposed in a gap between the refrigerator housing portion and the refrigerator. A thermal member.

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, the regeneration time of the cryopump can be shortened.

1 schematically shows a cryopump according to a first embodiment. The cryopump which concerns on 2nd Embodiment is shown schematically. The cryopump which concerns on 3rd 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 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.

(First embodiment)
FIG. 1 schematically shows a cryopump 10 according to the first embodiment. FIG. 1 shows a schematic side view of the cryopump 10.

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 a cryopump intake port (hereinafter also simply referred to as “intake port”) 12 for receiving a gas to be evacuated from the vacuum chamber. Gas enters the internal space of the cryopump 10 through the air inlet 12.

The cryopump 10 includes a refrigerator 16 and a cryopump housing 70. As the internal configuration of the cryopump 10, a well-known configuration may be employed, and an exemplary configuration will be described later with reference to FIG.

The cryopump housing 70 includes a shield housing portion 74 and a refrigerator housing portion 76. The shield housing portion 74 includes a housing bottom surface 70 a on the side opposite to the air inlet 12. The shield accommodating portion 74 surrounds the radiation shield in a non-contact manner with the radiation shield. The refrigerator housing unit 76 connects the shield housing unit 74 to the room temperature unit 26 of the refrigerator 16.

The shield accommodating portion 74 has a cylindrical or dome shape with one end opened as the air inlet 12 and the other end closed as the housing bottom surface 70a. The shield accommodating portion 74 includes an intake port flange 72 that defines the intake port 12.

In addition to the air inlet 12, an opening for inserting the refrigerator 16 is formed on the side wall of the shield housing portion 74 that connects the air inlet flange 72 to the housing bottom surface 70a. The refrigerator accommodating portion 76 has a cylindrical shape extending from the opening to the room temperature portion 26 of the refrigerator 16. The refrigerator housing portion 76 is formed integrally with the shield housing portion 74.

A rough valve 78 and a vent valve 80 for discharging gas or liquid from the cryopump 10 during regeneration are attached to the cylindrical side surface of the refrigerator housing portion 76. The rough valve 78 connects the cryopump housing 70 to the roughing pump 79. The vent valve 80 is provided to release a high pressure that can be generated inside the cryopump 10 to the external environment. A purge valve 82 for supplying purge gas to the inside of the cryopump 10 is attached to the shield housing portion 74. The purge valve 82 connects the cryopump housing 70 to the purge gas source 83. Roughing pump 79 and purge gas source 83 are typically not considered components of cryopump 10.

The arrangement of the rough valve 78, the vent valve 80, and the purge valve 82 is an example, and is not particularly limited. Such a valve may not be attached to the refrigerator accommodating portion 76. The rough valve 78 and the vent valve 80 may be attached to the shield housing portion 74. In addition, other components such as a vacuum gauge may be attached to the refrigerator housing portion 76.

An attachment flange 76 a for attaching to the room temperature part 26 of the refrigerator 16 is provided at the end of the refrigerator accommodating part 76 (that is, the end opposite to the shield accommodating part 74). A refrigerator flange 26a corresponding to the attachment flange 76a is provided in the room temperature portion 26, and the attachment flange 76a is fixed to the refrigerator flange 26a with an appropriate fastener such as a bolt. The room temperature unit 26 may be a motor housing that houses a motor that drives the refrigerator 16.

The cryopump 10 includes a first heater 84 disposed on the outer surface of the refrigerator housing portion 76 so as to apply heat from the outside to the inside of the cryopump housing 70. The first heater 84 is an electric heater. The first heater 84 has a sheet-like shape and is wound around a cylindrical side surface of the refrigerator housing portion 76. Although the 1st heater 84 has enclosed the perimeter of the refrigerator accommodating part 76, it is not essential. The first heater 84 may be partially provided in the circumferential direction of the refrigerator housing unit 76. The shape of the first heater 84 is arbitrary and is not limited to a sheet shape. For example, the first heater 84 may be a linear heater.

The first heater 84 is connected to a heater power supply 85. The regeneration of the cryopump 10 generally includes a temperature raising process, a discharging process, and a cool-down process. In the temperature raising step, the cryopanel is heated to the regeneration temperature. In the discharge process, the gas captured by the cryopump 10 is discharged. In the cool-down process, the cryopanel is re-cooled to a cryogenic temperature for evacuation operation. The heater power supply 85 turns on the first heater 84 in response to the start of regeneration of the cryopump 10 (for example, the start of the temperature raising process), and turns off the first heater 84 in response to the completion of the discharge process or the start of the cool-down process. It may be configured to be off.

The lower limit of the heating temperature of the first heater 84 may be selected so as to prevent freezing of water, and the upper limit may be selected based on the heat resistant temperature of the refrigerator 16. The heating temperature of the first heater 84 may be selected from a range of 10 ° C. to 50 ° C., or a range of 20 ° C. to 40 ° C., for example. This temperature setting is the same for the second heater 86 described later.

The first heater 84 is not limited to this, and may be any type of heating device. For example, the 1st heater 84 is provided with the piping of the temperature control fluid wound around the outer surface of the refrigerator accommodating part 76, or extended along the outer surface of the refrigerator accommodating part 76, for example, warm water or warm gas flows through this piping. Thus, heat may be applied from the outside to the inside of the cryopump housing 70.

Similarly to the first heater 84, the second heater described later may have an arbitrary shape. The second heater may be any type of heating device.

Note that the supply of purge gas to the cryopump 10 by the purge gas supply unit including the purge valve 82 and the purge gas source 83 can be regarded as a kind of heating means, but the first heater 84 does not include this. The first heater 84 is provided in the cryopump 10 as a heating device different from the purge gas supply unit.

The first heater 84 is disposed on the outer surface of the base portion 76 b of the refrigerator housing portion 76 adjacent to the room temperature portion 26. Here, the base portion 76 b of the refrigerator housing portion 76 refers to a portion of the refrigerator housing portion 76 that is close to the room temperature portion 26. The first heater 84 is attached to the base portion 76b of the refrigerator housing portion 76 adjacent to the mounting flange 76a. As shown in the figure, when the refrigerator housing unit 76 is provided with a valve, the first heater 84 is disposed between a valve (for example, the vent valve 80) closest to the room temperature unit 26 and the room temperature unit 26.

The cryopump 10 can have an inlet flange 72 attached to the vacuum chamber in the illustrated direction. The cryopump 10 can be used in a so-called vertical orientation. That is, the cryopump 10 may be used in a state in which the air inlet 12 and the housing bottom surface 70a are located above and the room temperature portion 26 of the refrigerator 16 is located below.

During the evacuation operation of the cryopump 10, water (that is, ice) captured by condensation on the cryopanel surface is heated and melted during the regeneration of the cryopump 10. In the case of the vertically arranged cryopump 10 shown in the figure, the melted water flows downward due to gravity and can accumulate on the bottom of the refrigerator housing unit 76 (directly above the room temperature unit 26). If the water level exceeds the vent valve 80, water can be discharged from the vent valve 80 to the outside of the cryopump 10 in a liquid state. However, if the water level does not reach the vent valve 80, it is necessary to evaporate the accumulated water for discharging.

The cooling action by evaporation lowers the temperature of the water accumulated at the bottom of the refrigerator housing section 76. In the worst case, the water surface or the whole of the accumulated water can be frozen again. A typical cryopump is equipped with heating means for regeneration. However, this typical heating means is disposed at a location away from the bottom of the refrigerator accommodating portion 76 (for example, the cooling stage of the refrigerator 16). For this reason, it is difficult to heat the water stored in the bottom of the refrigerator housing portion 76 so as to quickly evaporate it.

When the water accumulated at the bottom of the refrigerator accommodating portion 76 is cooled to a temperature lower than room temperature, for example, near the freezing point of water, the evaporation of moisture from the water surface accumulated at the bottom of the refrigerator accommodating portion 76 is significant. To be suppressed. Discharge of water by vaporization becomes substantially difficult, and the regeneration time can be extremely long. There is a possibility that the reproduction is not completed within a practically acceptable time.

However, in the cryopump 10 according to the first embodiment, the first heater 84 is disposed in the base portion 76b of the refrigerator housing unit 76. Therefore, the water accumulated at the bottom of the refrigerator housing portion 76 can be heated using the first heater 84 to prevent icing. Moreover, evaporation of water can be promoted by heating. Therefore, water can be discharged efficiently and the regeneration time can be shortened.

It should be noted that the first heater 84 may be disposed at any place as long as heat can be effectively applied to the water that can be accumulated in the refrigerator housing unit 76. For example, the first heater 84 may be disposed in the vicinity of the shield housing portion 74 away from the base portion 76 b of the refrigerator housing portion 76. When an additional structure such as a valve or a sensor is provided in the base portion 76b of the refrigerator housing portion 76, the arrangement of the first heater 84 avoiding such a structure may be appropriate.

Also, since the first heater 84 is mounted on the outer surface of the refrigerator housing portion 76, there is an advantage that it can be additionally installed in an existing cryopump that does not have such a heater.

(Second Embodiment)
FIG. 2 schematically shows a cryopump 10 according to the second embodiment. The cryopump 10 can have an inlet flange 72 attached to the vacuum chamber in the orientation shown. The cryopump 10 can be used in a horizontal direction. In other words, the cryopump 10 may be used in a state where the air inlet 12 is located above and the housing bottom surface 70a is located below.

A drain hole 87 may be formed at the bottom of the radiation shield 30. In this case, water melted during regeneration tends to accumulate at the bottom of the shield housing portion 74 through the drain hole 87.

The cryopump 10 includes a second heater 86 disposed on the housing bottom surface 70 a so as to apply heat from the outside to the inside of the cryopump housing 70. In this way, water that can accumulate at the bottom of the shield housing portion 74 can be heated by the second heater 86 in the case where the illustrated cryopump 10 is disposed sideways. Therefore, also by the cryopump 10 according to the second embodiment, water can be efficiently discharged and the regeneration time can be shortened, similarly to the cryopump 10 according to the first embodiment.

The second heater 86 is disposed only on the housing bottom surface 70 a in the shield housing portion 74. The second heater 86 is not provided on the side surface of the shield housing portion 74. In this way, a commercially available heater having a planar shape can be easily used as the second heater 86. The installation of the second heater 86 is easier than when the heaters are attached to both the side surface of the shield housing portion 74 and the housing bottom surface 70a. However, the 2nd heater 86 may be provided in both the side surface of the shield accommodating part 74, and the housing bottom face 70a as needed.

Like the first heater 84, the second heater 86 is connected to a heater power supply 85.

The cryopump 10 may include both the first heater 84 and the second heater 86.

Subsequently, an exemplary configuration of the internal components of the cryopump 10 will be described with reference to FIG. This configuration is applicable to the cryopump 10 shown in FIG. Moreover, it is applicable also to the cryopump 10 shown in FIG.

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 intake port 12 (the direction along the central axis A in FIG. 1), and the radial direction represents the direction along the intake port 12 (the direction perpendicular to the central axis A). 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 proximity to the center of the intake port 12 (center axis A in FIG. 1) may be referred to as “inside” and the proximity to the peripheral edge of the intake port 12 may be referred to as “outside”. 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 cryopanel unit 18, a second cryopanel unit 20, and a cryopump housing 70.

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 as to periodically repeat the supply and discharge of the working gas (for example, helium) to the inside of the refrigerator 16.

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 A of the cryopump 10.

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

The radiation shield 30 is provided to protect the second cryopanel unit 20 from the radiant heat of the cryopump housing 70. The radiation shield 30 is located between the cryopump housing 70 and the second cryopanel unit 20 and surrounds the second cryopanel unit 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 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 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 radiation shield 30 is thermally coupled to the first cooling stage 22 by attaching the first cooling stage 22 to the mounting seat 46.

Instead of attaching the radiation shield 30 directly to the first cooling stage 22 in this manner, in some embodiments, the radiation shield 30 is thermally coupled to the first cooling stage 22 via an additional heat transfer member. It may be. The heat transfer member may be a hollow short cylinder having flanges at both ends, for example. The heat transfer member may be fixed to the mounting seat 46 by a flange at one end and fixed to the first cooling stage 22 by a flange at the other end. The heat transfer member may extend from the first cooling stage 22 to the radiation shield 30 so as to surround the refrigerator structure 21. The shield side part 40 may include such a heat transfer member.

In the illustrated embodiment, the radiation shield 30 is configured as an integral cylinder. Instead of this, the radiation shield 30 may be configured to have a tubular shape as a whole by a plurality of parts. The plurality of parts may be arranged with a gap therebetween. For example, the radiation shield 30 may be divided into two parts in the axial direction. In this case, the upper part of the radiation shield 30 is a cylinder whose both ends are open, and includes a shield front end 36 and a first portion of the shield side part 40. The lower part of the radiation shield 30 is also a cylinder open at both ends, and includes a second part of the shield side part 40 and a shield bottom part 38. A slit extending in the circumferential direction is formed between the first portion and the second portion of the shield side portion 40. This slit may form at least a part of the shield side opening 44. Alternatively, the upper half of the shield side opening 44 may be formed in the first part of the shield side part 40, and the lower half may be formed in the second part of the shield side part 40.

The radiation shield 30 forms a gas receiving space 50 surrounding the second cryopanel unit 20 between the air inlet 12 and the shield bottom 38. The gas receiving space 50 is a part of the internal space 14 of the cryopump 10 and is a region adjacent to the second cryopanel unit 20 in the radial direction.

The inlet cryopanel 32 is configured to protect the second cryopanel unit 20 from radiant heat from a heat source outside the cryopump 10 (for example, a heat source in a vacuum chamber to which the cryopump 10 is attached). Main opening 34, and so on). Further, a gas (for example, moisture) that condenses at the cooling temperature of the inlet cryopanel 32 is captured on the surface thereof.

The inlet cryopanel 32 is disposed at a location corresponding to the second cryopanel unit 20 at the air inlet 12. The inlet cryopanel 32 occupies the central portion of the opening area of the air inlet 12, and forms an annular open region 51 with the radiation shield 30. The open area 51 is at a location corresponding to the gas receiving space 50 in the intake port 12. Since the gas receiving space 50 is on the outer peripheral portion of the internal space 14 so as to surround the second cryopanel unit 20, the open region 51 is located on the outer peripheral portion of the intake port 12. The open area 51 is an inlet of the gas receiving space 50, and the cryopump 10 receives gas into the gas receiving space 50 through the open area 51.

The inlet cryopanel 32 is attached to the shield front end 36 via an attachment member (not shown). Thus, the inlet cryopanel 32 is fixed to the radiation shield 30 and is thermally connected to the radiation shield 30. The inlet cryopanel 32 is close to the second cryopanel unit 20 but is not in contact with it.

The inlet cryopanel 32 has a planar structure disposed at the air inlet 12. The inlet cryopanel 32 may include, for example, a louver or chevron formed concentrically or in a lattice shape, or may include a flat plate (for example, a circular plate). The inlet cryopanel 32 may be disposed so as to cross the entire inlet 12. In that case, the open area | region 51 may be formed by missing a part of plate, or missing the louver of a part of louver or chevron.

The second cryopanel unit 20 is provided in the center of the internal space 14 of the cryopump 10. The second cryopanel unit 20 includes a plurality of cryopanels 60 and a panel mounting member 62. The panel attachment member 62 extends upward and downward in the axial direction from the second cooling stage 24. The second cryopanel unit 20 is attached to the second cooling stage 24 via a panel attachment member 62. In this way, the second cryopanel unit 20 is thermally connected to the second cooling stage 24. Therefore, the second cryopanel unit 20 is cooled to the second cooling temperature.

In the second cryopanel unit 20, an adsorption region 64 is formed on at least a part of the surface. The adsorption region 64 is provided for capturing a non-condensable gas (for example, hydrogen) by adsorption. The adsorption region 64 is formed in a location behind the cryopanel 60 adjacent above so as not to be seen from the air inlet 12. That is, the suction region 64 is formed in the upper surface central portion and the entire lower surface of each cryopanel 60. However, the suction region 64 is not provided on the upper surface of the top cryopanel 60a. The adsorption region 64 is formed by adhering an adsorbent (for example, activated carbon) to the cryopanel surface, for example.

Further, a condensing region 66 for capturing condensable gas by condensation is formed on at least a part of the surface of the second cryopanel unit 20. The condensation area 66 is, for example, an area where the adsorbent is missing on the cryopanel surface, and the cryopanel substrate surface, for example, a metal surface is exposed.

A plurality of cryopanels 60 are arranged on the panel mounting member 62 along the direction from the shield main opening 34 toward the shield bottom 38 (that is, along the central axis A). Each of the plurality of cryopanels 60 is a flat plate (for example, a circular plate) extending perpendicularly to the central axis A, and is attached to the panel attachment member 62 in parallel with each other. For convenience of explanation, the one closest to the inlet 12 among the plurality of cryopanels 60 may be referred to as the top cryopanel 60a, and the one closest to the shield bottom 38 among the plurality of cryopanels 60 may be referred to as the bottom cryopanel 60b. .

The second cryopanel unit 20 extends elongated along the axial direction between the air inlet 12 and the shield bottom 38. The distance from the upper end to the lower end of the second cryopanel unit 20 in the axial direction is longer than the external dimension of the vertical projection of the second cryopanel unit 20 in the axial direction. For example, the distance between the top cryopanel 60a and the bottom cryopanel 60b is larger than the width or diameter of the cryopanel 60.

The plurality of cryopanels 60 may have the same shape as illustrated, or may have different shapes (for example, different diameters). A certain cryopanel 60 among the plurality of cryopanels 60 may have the same shape as that of the cryopanel 60 adjacent above the cryopanel 60 or may be large. As a result, the bottom cryopanel 60b may be larger than the top cryopanel 60a. The area of the bottom cryopanel 60b may be about 1.5 times to about 5 times the area of the top cryopanel 60a.

Further, the intervals between the plurality of cryopanels 60 may be constant as shown in the figure, or may be different from each other.

The cryopump housing 70 is a housing of the cryopump 10 that houses the first cryopanel unit 18, the second cryopanel unit 20, and the refrigerator 16, and is configured to maintain the vacuum airtightness of the internal space 14. It is a vacuum vessel. The cryopump housing 70 includes the first cryopanel unit 18 and the refrigerator structure portion 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 vacuum evacuation operation of the cryopump 10 having the above configuration 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 cryopanel unit 18 and the second cryopanel unit 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. 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 enters the internal space 14 from the air inlet 12. Alternatively, the other part of the gas is reflected by the inlet cryopanel 32 and does not enter the internal space 14.

The gas that has entered the internal space 14 is cooled by the second cryopanel unit 20. A gas having a sufficiently low vapor pressure (for example, 10 ⁻⁸ Pa or less) is condensed on the surface of the second cryopanel unit 20 at the second cooling temperature. This gas may be referred to as a second type gas. The second type gas is, for example, argon. Thus, the second cryopanel unit 20 can exhaust the second type gas.

The gas whose vapor pressure is not sufficiently low at the second cooling temperature is adsorbed by the adsorbent of the second cryopanel unit 20. This gas may be referred to as a third type gas. The third type gas is, for example, hydrogen. Thus, the second cryopanel unit 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.

(Third embodiment)
FIG. 3 schematically shows a cryopump 10 according to the third embodiment.

The cryopump 10 includes a heat transfer member 88 that is thermally coupled to the first cooling stage 22 and disposed in a gap between the refrigerator housing unit 76 and the refrigerator 16. The illustrated heat transfer member 88 includes two heat transfer rods, but may include one or three or more heat transfer rods. Similar to the first cooling stage 22, the heat transfer member 88 is formed of a high thermal conductivity material, such as copper.

One end of the heat transfer member 88 is fixed to the first cooling stage 22, and the other end is located in the vicinity of the base portion 76 b of the refrigerator housing portion 76. The heat transfer member 88 extends along the first cylinder 23 between the refrigerator housing portion 76 and the first cylinder 23. The heat transfer member 88 may extend linearly in parallel with the first cylinder 23, or may be curved (for example, spirally around the first cylinder 23). The shape of the heat transfer member 88 is arbitrary.

The end of the heat transfer member 88 is slightly separated from the room temperature part 26 of the refrigerator 16 and is not physically in contact with the room temperature part 26. The distance between the heat transfer member 88 and the room temperature portion 26 is, for example, about several mm. The heat transfer member 88 is not in contact with the first cylinder 23.

The refrigerator 16 enables so-called reverse temperature increase. The refrigerator 16 includes a reversible motor 90 and is configured to switch between cooling and heating of the first cooling stage 22 and the second cooling stage 24 according to the rotation direction of the reversible motor 90. When the first cooling stage 22 is cooled, the heat transfer member 88 is also cooled, and when the first cooling stage 22 is heated, the heat transfer member 88 is also heated. The reversible motor 90 is accommodated in the room temperature portion 26. Since it is already well known that the reverse temperature rise of the refrigerator 16 is used as a heat source for the regeneration of the cryopump 10, details thereof will not be described here.

It should be noted that a heating element such as an electric heater may be disposed on the first cooling stage 22 so that the heat transfer member 88 may be heated.

In the case of the vertically arranged cryopump 10 shown in the figure, the end of the heat transfer member 88 can be immersed in the water accumulated at the bottom of the refrigerator accommodating portion 76. Therefore, the heat transfer member 88 heated by the first cooling stage 22 can heat the water accumulated at the bottom of the refrigerator housing unit 76. Similarly to the cryopump 10 according to the first embodiment, the cryopump 10 according to the third embodiment can efficiently discharge water and shorten the regeneration time.

The cryopump 10 may include a combination of the first heater 84 and the heat transfer member 88 or a combination of the second heater 86 and the heat transfer member 88. The cryopump 10 may include a first heater 84, a second heater 86, and a heat transfer member 88.

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 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 central axis A of the cryopump 10. In this case, in the cryopump housing 70, an opening through which the refrigerator 16 is inserted is formed in the housing bottom surface 70a. The refrigerator accommodating portion 76 extends from this opening to the room temperature portion 26 of the refrigerator 16, and connects the shield accommodating portion 74 to the room temperature portion 26. The first heater 84 may be disposed on the outer surface of the refrigerator housing portion 76, for example, the outer surface of the base portion 76 b of the refrigerator housing portion 76. The second heater 86 may be disposed on the housing bottom surface 70a.

10 cryopump, 12 inlet, 16 freezer, 22 1st cooling stage, 24 2nd cooling stage, 26 room temperature section, 30 radiation shield, 70 cryopump housing, 70a housing bottom, 74 shield housing section, 76 refrigerator housing Part, 84, first heater, 86, second heater, 88 heat transfer member, 90 reversible motor.

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

Claims

A refrigerator having a room temperature section, a first cooling stage, and a second cooling stage;
A radiation shield that is thermally coupled to the first cooling stage and surrounds the second cooling stage in non-contact with the second cooling stage;
A cryopump air inlet, a housing bottom surface on the opposite side of the cryopump air inlet, a shield housing portion surrounding the radiation shield in a non-contact manner with the radiation shield, and the shield housing portion serving as the room temperature of the refrigerator A cryopump housing comprising a refrigerator housing unit connected to the unit,
A cryopump comprising: a heater disposed on an outer surface of the refrigerator housing portion or a bottom surface of the housing so as to apply heat from the outside to the inside of the cryopump housing.
The cryopump according to claim 1, wherein the heater is disposed on an outer surface of a base portion of the refrigerator housing portion adjacent to the room temperature portion.
The cryopump according to claim 1 or 2, further comprising a heat transfer member that is thermally coupled to the first cooling stage and disposed in a gap between the refrigerator housing portion and the refrigerator.
The refrigerating machine includes a reversible motor, and is configured to switch between cooling and heating of the first cooling stage and the heat transfer member according to a rotation direction of the reversible motor. 3. The cryopump according to 3.
A refrigerator having a room temperature section, a first cooling stage, and a second cooling stage;
A radiation shield thermally coupled to the first cooling stage and surrounding the second cooling stage;
A cryopump air inlet, a housing bottom surface on the opposite side of the cryopump air inlet, a shield housing portion surrounding the radiation shield in a non-contact manner with the radiation shield, and the shield housing portion serving as the room temperature of the refrigerator A cryopump housing comprising a refrigerator housing unit connected to the unit,
A cryopump comprising: a heat transfer member thermally coupled to the first cooling stage and disposed in a gap between the refrigerator housing portion and the refrigerator.