Refrigerator and cryopump

Abstract

To provide a refrigerator and a cryopump, in which a coating layer with better wear resistance is formed on a displacer surface.SOLUTION: A refrigerator has: a refrigerator cylinder having a first-stage cylinder and a second-stage cylinder that is configured to have a smaller inner diameter than the first-stage cylinder and is coupled to the first-stage cylinder; a first-stage displacer disposed inside the first-stage cylinder; a first-stage cold storage device disposed inside the first-stage displacer; a second-stage displacer that is configured to have a smaller outer diameter than the first-stage displacer, is disposed inside the second-stage cylinder, and is coupled to the first-stage displacer; a second-stage cold storage device disposed inside the second-stage displacer; and a reciprocating mechanism that reciprocates the first-stage displacer and the second-stage displacer in a direction along the center axis line of the refrigerator cylinder. A non-fluorine coating layer is formed on the outer peripheral surface of the second-stage displacer, and a clearance is provided between the coating layer and the second-stage cylinder.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a refrigerator and a cryopump.

Background Art

[0002] In an extremely low temperature environment, since lubricating oil becomes solid at low temperature, an oil seal cannot be used in a refrigerator. Therefore, as a sealing material, an organic fluorine compound that contacts a mating material in a lubrication-free environment, has lubricity even when a certain surface pressure is applied, and is excellent in wear resistance may be used.

[0003] For example, in a cryopump using a refrigerator, the refrigerator cylinder and the two-stage displacer are made of the same material, and for example, stainless steel is adopted as the material. A predetermined clearance is provided between the refrigerator cylinder and the two-stage displacer in order to maintain a state with low conductance from room temperature to low temperature. And since the sliding property is poor when the refrigerator cylinder and the two-stage displacer separated by a narrow clearance are made of stainless steel, an organic fluorine compound such as ethylene / tetrafluoroethylene copolymer (ETFE) or fluororesin, which is excellent in wear resistance, is coated on the surface of the displacer (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the above refrigerator, since the refrigerator cylinder and the two-stage displacer are arranged with a narrow clearance therebetween, it is required to form a coating layer with more excellent wear resistance on the surface of the displacer.

[0006] In view of the above circumstances, an object of the present invention is to provide a refrigerator in which a coating layer having more excellent wear resistance is formed on the surface of a displacer, and a cryopump using this refrigerator.

Means for Solving the Problems

[0007] To achieve the above object, a refrigerator according to one embodiment of the present invention includes: a refrigerating cylinder having a cylindrical first-stage cylinder and a cylindrical second-stage cylinder configured to have a smaller inner diameter than the first-stage cylinder and connected to the first-stage cylinder; a cylindrical first-stage displacer disposed inside the first-stage cylinder; a first-stage regenerator disposed inside the first-stage displacer; a cylindrical second-stage displacer configured to have a smaller outer diameter than the first-stage displacer, disposed inside the second-stage cylinder, and connected to the first-stage displacer; a second-stage regenerator disposed inside the second-stage displacer; in the refrigerating cylinder into which a cooling gas is introduced, a reciprocating mechanism for reciprocating the first-stage displacer and the second-stage displacer in a direction along the central axis of the refrigerating cylinder. a non-fluorine-based coating layer is formed on the outer peripheral surface of the second-stage displacer; a clearance is provided between the coating layer and the second-stage cylinder.

[0008] According to such a refrigerator, a refrigerator in which a coating layer having more excellent wear resistance is formed on the surface of a displacer is provided.

[0009] In the above refrigerator, the coating layer may include at least one of diamond-like carbon (DLC), titanium nitride, titanium carbide, ceramic, polyimide (PI), and polyether ether ketone (PEEK).

[0010] According to such a refrigerator, a refrigerator is provided in which a coating layer having more excellent wear resistance is formed on the surface of the displacer.

[0011] To achieve the above object, a cryopump according to an aspect of the present invention is a cryopump that evacuates gas in a vacuum chamber, the above refrigerator, and includes a cooling plate that is cooled by the refrigerator and condenses or adsorbs and removes the gas in the vacuum chamber.

[0012] According to such a cryopump, a cryopump including a refrigerator in which a coating layer having more excellent wear resistance is formed on the surface of the displacer is provided.

Effects of the Invention

[0013] As described above, according to the present invention, a refrigerator in which a coating layer having more excellent wear resistance is formed on the surface of the displacer and a cryopump using this refrigerator are provided.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same members or members having the same function may be given the same reference numerals, and the description may be omitted as appropriate after the description of such members. Also, the numerical values shown below are examples and are not limited to this example.

[0016] (Vacuum processing apparatus) FIG. 1 is a schematic cross-sectional view showing an example of a vacuum processing apparatus to which a cryopump of the present embodiment is attached. The refrigerator of the present embodiment can also be applied to a refrigerator for cooling a superconducting magnet used in MRI or MCZ.

[0017] The vacuum processing apparatus 60 has a vacuum chamber 66. An evaporation source (film forming source) 68 is disposed inside the vacuum chamber 66, and a substrate disposing device (substrate holder) 63 is disposed above the evaporation source 68.

[0018] The vacuum processing apparatus 60 is, for example, a sputtering apparatus, an etching apparatus, or the like. The refrigerator 30 is a refrigerator having a displacer and a cold storage. The refrigerator 30 is, for example, a refrigerator in which a displacer reciprocates in a refrigerator cylinder.

[0019] A vacuum pump 69 and a cryopump 61 are connected to the vacuum chamber 66. The vacuum chamber 66 is preliminarily evacuated by the vacuum pump 69. An exhaust port 88 is provided on the bottom surface of the vacuum chamber 66. When the pressure in the vacuum chamber 66 drops to a predetermined pressure, the cryopump 61 operates to lower the internal pressure of the vacuum chamber 66 to a high vacuum atmosphere.

[0020] The vacuum chamber 66 is connected to a transfer chamber 97. Another vacuum processing apparatus 90 is connected to the transfer chamber 97. For example, the substrate 62 is carried into the inside of the vacuum chamber 66 through the transfer chamber 97 while maintaining a vacuum atmosphere from the vacuum processing apparatus 90.

[0021] The central part of the substrate placement device 63 is penetrated. When the film-forming material is released from the evaporation source 68, the film-forming material passes through the through-hole and reaches the substrate 62. Thereby, a thin film is formed on the substrate 62. A mask member may be disposed between the substrate 62 and the evaporation source 68 as necessary.

[0022] (Cryopump) FIG. 2 is a schematic cross-sectional view showing an example of the cryopump of the present embodiment.

[0023] The cryopump 61 evacuates the gas in the vacuum chamber 66. The cryopump 61 has a pump main body portion 71 and a refrigerator 30. The refrigerator 30 has a motor portion 53 and a refrigeration portion 54.

[0024] In the pump main body portion 71, a low-temperature baffle 87 cooled to 80K (Kelvin) and a low-temperature shield 82 cooled to 80K are provided inside a pump case 83 (vacuum evacuation chamber) that can maintain vacuum tightness. The low-temperature baffle 87 and the low-temperature shield 82 can absorb most of the radiant heat flowing in from the vacuum processing apparatus 60. Inside the pump main body portion 71, a cryopanel 76 (cryogenic plate) cooled to an extremely low temperature of 15K is disposed. The low-temperature baffle 87, the low-temperature shield 82, and the cryopanel 76 are collectively referred to as a cooling plate that is cooled by the refrigerator 30 to condense or adsorb and remove the gas in the vacuum chamber 66.

[0025] The motor portion 53 is disposed outside the vacuum atmosphere of the cryopump 61, and a motor driven by an AC power source is built in the motor portion 53.

[0026] The refrigeration portion 54 is disposed in a heat-insulated vacuum atmosphere so as not to be affected by heat input by radiation or heat conduction.

[0027] The refrigeration unit 54 includes a cylinder body 91 on the pump case 83 side, a pump case side flange 92, a bellows 93, a motor unit side flange 99, and a refrigeration case 95. All components constituting the refrigeration unit 54 are made to be airtight by welding or an elastic body. The space surrounding the refrigeration unit 54 is in a vacuum state similar to the inside of a cryopump.

[0028] The pump case side flange 92 and the motor unit side flange 99 are fixed to each other via a vibration isolator 55. A stretchable bellows 93 is arranged between the pump case side flange 92 and the motor unit side flange 99.

[0029] A first-stage cylinder 3 is arranged inside the refrigeration case 95. A second-stage cylinder 5 is arranged inside the pump case 83. The first-stage cylinder 3 and the second-stage cylinder 5 are hermetically connected, and the first-stage cylinder 3 and the second-stage cylinder 5 form a refrigeration machine cylinder 100 into which helium gas is introduced.

[0030] One end (the left end in FIG. 2) of the refrigeration machine cylinder 100 is fixed to the motor unit 53. When the portion of the refrigeration machine cylinder 100 attached to the motor unit 53 is taken as the base side of the refrigeration machine cylinder 100, the opposite tip side with respect to the base side of the refrigeration machine cylinder 100 is inserted into the low-temperature shield 82 in a non-contact manner. The tip side of the refrigeration machine cylinder 100 is connected to the low-temperature shield 82. The low-temperature baffle 87 is connected to the low-temperature shield 82.

[0031] Of the gas incident on the cryopump inlet 89 via the exhaust port 88 from the vacuum chamber 66, the gas with a low vapor pressure, for example, H2O, is condensed by the low-temperature baffle 87 and the low-temperature shield 82 that are cooled (for example, to 80 K) by the first stage of the refrigerator cylinder 100. Also, among this gas, N2, O2, Ar, H2, etc., which have a high vapor pressure other than water, pass through the low-temperature baffle 87 and condense or adsorb on the cryopanel 76 that is cooled (for example, to 15 K or lower) by the second stage of the refrigerator cylinder 100. The cryopanel 76 is connected at the tip of the refrigerator cylinder 100 via the mounting member 84.

[0032] The motor unit 53 is fixed to the motor unit side flange 99 by the refrigeration case 95. The motor unit side flange 99 is fixed to the pump case side flange 92 by the vibration isolation device 55.

[0033] The pump case side flange 92 is fixed to the pump case 83 by the cylindrical body 91 on the pump case 83 side. The cryopanel 76, the refrigeration unit 54, and the refrigerator cylinder 100 disposed inside thereof, and the motor unit 53 are supported by the pump case 83 via the vibration isolation device 55.

[0034] (Refrigerator) FIG. 3 is a schematic cross-sectional view showing an example of the refrigerator of the present embodiment.

[0035] The refrigerator cylinder 100 included in the refrigerator 30 has a first-stage cylinder 3 and a second-stage cylinder 5 connected to the first-stage cylinder 3. The first-stage cylinder 3 and the second-stage cylinder 5 have a cylindrical shape (tubular shape). The second-stage cylinder 5 is configured to have a smaller inner diameter than the first-stage cylinder 3. One end of the first-stage cylinder 3 and one end of the second-stage cylinder 5 are connected. Thereby, one refrigerator cylinder 100 is formed. A flange 35 is provided at the connection portion. The refrigerator cylinder 100 is made of, for example, stainless steel.

[0036] If the upper surface of the other end of the first-stage cylinder 3 is the first-stage flange 20 and the bottom surface of the other end of the second-stage cylinder 5 is the second outer bottom plate 37, the interior of the first-stage cylinder 3 and the interior of the second-stage cylinder 5 are sealed airtight by the first-stage flange 20, the flange 35, and the second outer bottom plate 37. High-purity helium gas, which is the refrigerant of the refrigerator, is sealed in the interior of the first-stage cylinder 3 and the interior of the second-stage cylinder 5.

[0037] A through-hole is provided in the first-stage flange 20, and a rod 31 is inserted through the through-hole in an airtight and movable manner. The tip of the rod 31 is located inside the first-stage cylinder 3. A presser plate (upper cap) 32a is provided at the tip of the rod 31.

[0038] A cylindrical first-stage displacer 2 is arranged inside the first-stage cylinder 3. Inside the second-stage cylinder 5, a cylindrical second-stage displacer 4 with a smaller inner diameter and outer diameter than the first-stage displacer 2 and one end connected to the first-stage displacer 2 is arranged. The first-stage displacer 2 is made of, for example, a thermosetting resin, and the second-stage displacer 4 is made of, for example, stainless steel. A coating layer is formed on the outer peripheral surface of the second-stage displacer 4 (described later).

[0039] The first-stage cylinder 3, the second-stage cylinder 5, the first-stage displacer 2, and the second-stage displacer 4 are arranged such that the central axis 301 of the first and second-stage cylinders 3 and 5 and the central axis 302 of the first and second-stage displacers 2 and 4 coincide. The central axis 301 and the central axis 302 form the central axis 300 of the refrigerator cylinder 100.

[0040] The first-stage regenerator 8 is arranged in the internal space of the first-stage displacer 2. The second-stage regenerator 10 is arranged in the internal space of the second-stage displacer 4.

[0041] The displacer 2 has a small-diameter portion 33 with a cylindrical shape and a large-diameter portion 34 with a cylindrical shape having a larger diameter than the small-diameter portion 33. The upper end portion of the second-stage displacer 4 is connected to the small-diameter portion 33 of the large-diameter portion 34 and the end face on the opposite side thereof. A rod 31 is inserted through a through-hole formed in the first-stage flange 20 in an airtight and movable manner. When the rod 31 reciprocates in the axial direction by the motor unit 53, the pressing plate 32a, the first-stage displacer 2, and the second-stage displacer 4 reciprocate together along the central axis 300 within the space formed by the inside of the first-stage cylinder 3 and the inside of the second-stage cylinder 5.

[0042] That is, a reciprocating mechanism for reciprocating the first and second-stage cylinders 3 and 5 is constituted by the motor unit 53 and the rod 31. In this way, in the refrigerator cylinder 100 into which helium gas as a refrigerant gas is introduced, the first-stage displacer 2 and the second-stage displacer 4 are reciprocated in the direction along the central axis 300 of the refrigerator cylinder 100.

[0043] In the small-diameter portion 33, a first-stage O-ring 1 and an auxiliary ring 13a made of resin and having an annular shape are arranged with their inner circumferences in contact with the outer circumference of the small-diameter portion 33. The inner circumference of a first-stage cap 21 made of resin is arranged in contact with the outer circumference of the first-stage O-ring 1. The first-stage O-ring 1 and the first-stage cap 21 constitute a first-stage seal member 22. The outer circumferential surface of the first-stage cap 21 and the outer circumferential surface of the auxiliary ring 13a are in contact with the inner circumferential surface of the first-stage cylinder 3.

[0044] Between the second-stage displacer 4 and the second-stage cylinder 5, the conductance is reduced by a minute clearance, suppressing the amount of helium gas passing through during the time when the second-stage displacer reciprocates.

[0045] The refrigerator 30 has a compressor (not shown). When the refrigerator 30 is operated, the first and second stage displacer 2, 4 are separated from the first stage flange 20. An introduction space 12 is formed between the first stage flange 20 and the first stage displacer 2 inside the first and second stage cylinders 3, 5. The first stage flange 20 is provided with an inlet 23. High-pressure helium gas supplied by the compressor is introduced into the introduction space 12 through the inlet 23.

[0046] After the high-pressure helium gas is introduced into the introduction space 12, the first stage displacer 2 moves in the direction of the first stage flange 20 by the movement of the rod 31. As a result, a first stage expansion space 9 is formed on the side opposite to the introduction space 12 inside the first stage cylinder 3, and a second stage expansion space 11 is formed between the second stage displacer 4 and the bottom surface of the second stage cylinder 5 inside the second stage cylinder 5. When the first and second stage expansion spaces 9, 11 reach the maximum volume, the volume of the introduction space 12 becomes minimum.

[0047] The pressing plate 32a and the small diameter portion 33 are provided with a first flow path 24 which is a through hole. Further, the first stage displacer 2 is provided with a second flow path 25 connecting the space where the first stage regenerator 8 is disposed and the first stage expansion space 9. The second stage displacer 4 is provided with a third flow path 26 connecting the first stage expansion space 9 and the space where the second stage regenerator 10 is disposed, and a fourth flow path 27 connecting the second stage expansion space 11 and the space where the second stage regenerator 10 is disposed.

[0048] When the first and second stage expansion spaces 9, 11 are formed, the high-pressure helium gas introduced into the introduction space 12 passes through the first flow path 24 and flows into the space where the first stage regenerator 8 is disposed. After the high-pressure helium gas is cooled by the first stage regenerator 8, it passes through the second flow path 25 and flows into the first stage expansion space 9. Further, the high-pressure helium gas flowing into the first stage expansion space 9 passes through the third flow path 26 and flows into the space where the second stage regenerator 10 is disposed. Then, the high-pressure helium gas is cooled by the second stage regenerator 10 and passes through the fourth flow path 27 and flows into the second stage expansion space 11.

[0049] In this state, when the inlet 23 is connected to a compressor (not shown), the high-pressure helium gas flowing into the first and second stage expansion spaces 9 and 11 flows through the spaces where the first to fourth flow paths 24 to 27 are arranged while flowing backward and expanding, and while cooling the first and second stage regenerators 8 and 10. Then, the high-pressure helium gas cools the first and second stage regenerators 8 and 10 while the pressure decreases, and moves to the compressor (not shown).

[0050] The helium gas returned to the compressor (not shown) is compressed while dissipating heat inside the compressor, and becomes high-pressure helium gas.

[0051] In the present embodiment, regarding the movement when forming the first and second stage expansion spaces 9 and 11, the movement of the first and second stage displacer 2 and 4 in the direction approaching the first stage flange 20 is defined as the forward stroke. Also, regarding the movement when forming the introduction space 12, the movement of the first and second stage displacer 2 and 4 in the direction away from the first stage flange 20 is defined as the return stroke. By repeating the introduction of high-pressure helium gas into the introduction space 12, the forward stroke, the movement of the high-pressure helium gas that has moved to the first and second stage expansion spaces 9 and 11 to the compressor, and the return stroke, a temperature gradient is formed in the first and second stage regenerators 8 and 10. As a result, the lower ends of the first and second stage cylinders 3 and 5 are cooled, and the low-temperature baffle 87, the low-temperature shield 82, the cryopanel 76, etc. are cooled.

[0052] FIG. 4 is a schematic cross-sectional view of the portion surrounded by the broken line L1 in FIG. 3.

[0053] In the refrigerator 30 of the present embodiment, in order to avoid damage to the second stage displacer 4 when the metal materials of the second stage displacer 4 and the second stage cylinder 5 come into contact with each other due to the above operation, a non-fluorine-based coating layer 41 is formed on the outer peripheral surface 40 of the second stage displacer 4. The coating layer 41 is formed by, for example, vacuum film formation or baking treatment such as CVD, sputtering method, and vapor deposition method.

[0054] Between the coating layer 41 and the second-stage cylinder 5, a clearance C1 is provided between the coating layer 41 and the second-stage cylinder 5 in order to avoid contact between them as much as possible. This clearance C1 is controlled to a length such that helium gas does not pass through in order to provide a temperature difference between the first-stage cylinder 3 and the second-stage cylinder 5. For example, the clearance C1 is configured to be 20 μm or more and 50 μm or less.

[0055] Examples of the material of the coating layer 41 include ceramics such as diamond-like carbon (DLC), titanium nitride, and titanium carbide, polyimide (PI), and polyether ether ketone (PEEK), which are more wear-resistant than organic fluorine compounds. The coating layer 41 includes at least one of ceramics such as diamond-like carbon (DLC), titanium nitride, and titanium carbide, polyimide (PI), and polyether ether ketone (PEEK).

[0056] For example, when the coating layer 41 is composed of a diamond-like carbon layer, the thickness of the diamond-like carbon layer is configured to be 0.3 μm or more and 2 μm or less. If the thickness of the diamond-like carbon layer is less than 0.3 μm, the unevenness of the base material appears on the surface after coating, which is not preferable. If it is more than 2 μm, the adhesion deteriorates and it is likely to peel off, which is not preferable.

[0057] For example, when the coating layer 41 is composed of a titanium nitride layer or a titanium carbide layer, the thickness of the titanium nitride layer or the titanium carbide layer is configured to be 0.1 μm or more and 5.0 μm or less. If the thickness of the titanium nitride layer or the titanium carbide layer is less than 0.1 μm, the unevenness of the base material appears on the surface after coating, which is not preferable. If it is more than 5.0 μm, the adhesion deteriorates and it is likely to peel off, which is not preferable.

[0058] For example, when the coating layer 41 is composed of a ceramic layer, the thickness of the ceramic layer is configured to be 15 μm or more and 30 μm or less. If the thickness of the ceramic layer is less than 15 μm, exposure of the base material occurs due to coating unevenness, which is not preferable. If it is more than 30 μm, the adhesion deteriorates and it becomes easy to peel off, which is not preferable.

[0059] For example, when the coating layer 41 is composed of a polyimide layer, the thickness of the polyimide layer is configured to be 20 μm or more and 50 μm or less. If the thickness of the polyimide layer is less than 20 μm, exposure of the base material occurs due to coating unevenness, which is not preferable. If it is more than 50 μm, the adhesion deteriorates and it becomes easy to peel off, which is not preferable.

[0060] For example, when the coating layer 41 is composed of a polyetheretherketone layer, the thickness of the polyetheretherketone layer is configured to be 20 μm or more and 40 μm or less. If the thickness of the polyetheretherketone layer is less than 20 μm, exposure of the base material occurs due to coating unevenness, which is not preferable. If it is more than 40 μm, the adhesion deteriorates and it becomes easy to peel off, which is not preferable.

[0061] As the material of the coating layer 41, an organic fluorine compound has been conventionally used, and the above materials have not been used. This is based on the reason that even the conventional coating of an organic fluorine compound had sufficient durability for the maintenance interval (for example, 10,000 hours). In contrast, by adopting the material of the present embodiment, the maintenance interval can be extended (for example, 36,000 hours).

[0062] The coating layer 41 is formed at a high density by vacuum deposition or baking treatment. Therefore, the mechanical strength of the coating layer 41 is higher than that in the case of using an organic fluorine compound. By forming the coating layer 41 on the outer peripheral surface 40 of the second-stage displacer 4, the wear resistance in a lubrication-free environment is improved compared to that of the organic fluorine compound. Also, the slidability with respect to the second-stage cylinder 5 is further improved. Further, uneven wear of the coating layer 41 is less likely to occur. As a result, the reliability of the coating layer 41 in a low-temperature environment is increased.

[0063] (Modification example) FIG. 5 is a schematic cross-sectional view showing a modification example of the refrigerator of the present embodiment. FIG. 6(a) is a schematic cross-sectional view showing a first modification example of the portion surrounded by the broken line L2 in FIG. 5. FIG. 6(b) is a schematic cross-sectional view showing a second modification example of the portion surrounded by the broken line L2 in FIG. 5

[0064] As shown in FIG. 5, a spiral groove 45 may be provided on the outer peripheral surface 40 of the second-stage displacer 4. In this case, as shown in FIG. 6(a), the coating layer 41 is formed on the outer peripheral surface 40 of the second-stage displacer 4, and the spiral groove 45 can be provided by subsequent processing. Also, after providing the spiral groove 45 on the outer peripheral surface 40 of the second-stage displacer 4, the coating layer 41 may be formed. In this case, as shown in FIG. 6(b), the coating layer 41 is formed along the outer peripheral surface 40 of the second-stage displacer 4 and the inner peripheral surface 450 of the spiral groove 45. Such a configuration is also included in the present embodiment.

[0065] As described above, the embodiments of the present invention have been described. However, the present invention is not limited only to the above-described embodiments, and it goes without saying that various modifications can be made. Each embodiment is not necessarily an independent form, and can be combined as much as technically possible.

Explanation of reference numerals

[0066] 1... First O-ring 2... First-stage displacer 3... First-stage cylinder 4... Second-stage displacer 5…Second-stage cylinder 8…First-stage regenerator 9…First-stage expansion space 10…Second-stage regenerator 11…Second-stage expansion space 12…Introduction space 13a…Auxiliary ring 20…First-stage flange 21…First-stage cap 22…First-stage seal member 23…Inlet 24…First flow path 25…Second flow path 26…Third flow path 27…Fourth flow path 30…Refrigerator 31…Rod 32a…Pressing plate 33…Small-diameter part 34…Large-diameter part 35…Flange 37…Outer bottom plate 40…Outer peripheral surface 41…Coating layer 45…Spiral groove 450…Inner peripheral surface 53…Motor part 54…Refrigeration part 55…Vibration isolator 60…Vacuum treatment device 61…Cryopump 62…Substrate 63…Substrate placement device 66…Vacuum chamber 68…Evaporation source 69…Vacuum pump 71…Pump body part 76…Cryopanel 82…Cryogenic shield 83…Pump case 84…Mounting member 87…Cryogenic baffle 88…Exhaust port 89…Cryopump intake port 90…Vacuum treatment device 91…Cylindrical body 92…Pump case side flange 93…Bellows 95…Freezing case 97…Conveyor room 99…Motor part side flange 100…Refrigerator cylinder 300, 301, 302…Central axis C1…Clearance

Claims

1. A refrigerator cylinder having a cylindrical first-stage cylinder and a cylindrical second-stage cylinder configured with a smaller inner diameter than the first-stage cylinder and connected to the first-stage cylinder, a cylindrical first-stage displacer disposed inside the first-stage cylinder, a first-stage regenerator disposed inside the first-stage displacer, a cylindrical second-stage displacer configured with a smaller outer diameter than the first-stage displacer, disposed inside the second-stage cylinder, and connected to the first-stage displacer, a second-stage regenerator disposed inside the second-stage displacer, in the refrigerator cylinder into which a cooling gas is introduced, a reciprocating mechanism for reciprocating the first-stage displacer and the second-stage displacer in a direction along the central axis of the refrigerator cylinder is provided, a non-fluorine-based coating layer is formed on the outer peripheral surface of the second-stage displacer, a clearance is provided between the coating layer and the second-stage cylinder refrigerator.

2. The refrigerator according to Claim 1, wherein the coating layer includes at least one of diamond-like carbon (DLC), titanium nitride, titanium carbide, ceramic, polyimide (PI), and polyether ether ketone (PEEK) refrigerator.

3. A cryopump for evacuating the gas in a vacuum chamber, comprising the refrigerator according to Claim 1 or 2, and a cooling plate that is cooled by the refrigerator and condenses or adsorbs and removes the gas in the vacuum chamber cryopump.

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