Cryopump, cryopump system, and method for starting operation of cryopump

Abstract

The cryogenic pump (10) of the present invention comprises: a non-flammable adsorbent material (64); and a controller (100), wherein the controller sequentially executes the following steps in order to start the vacuum exhaust operation of the cryogenic pump (10): dehydrating the non-flammable adsorbent material (64) by exposing the non-flammable adsorbent material (64) to a dry environment at room temperature or a temperature higher than room temperature; after dehydrating the non-flammable adsorbent material (64), vacuum exhausting the surrounding environment of the non-flammable adsorbent material (64); and cooling the non-flammable adsorbent material (64) to an ultra-low temperature in a vacuum environment.

Description

Technical Field

[0001] The present invention relates to a cryopump, a cryopump system and a method for starting operation of the cryopump. Background Art

[0002] A cryopump is a vacuum pump that captures gas molecules in a cryopanel cooled to an ultra-low temperature by condensation or adsorption and then exhausts them. Cryopumps are generally used to achieve a clean vacuum environment required in semiconductor circuit manufacturing processes, etc. Cryopumps are so-called gas capture vacuum pumps, so they need to be regenerated regularly to exhaust the captured gas to the outside.

[0003] Previous technical literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 5-263760 Summary of the invention

[0006] Technical issues to be solved by the invention

[0007] In order to adsorb non-condensable gases such as non-condensable hydrogen to the cryopanel, the cryopanel of the cryopump has an adsorbent. The typical adsorbent is activated carbon, and in a certain application, a gas containing oxygen or ozone is exhausted by the cryopump. In this case, during regeneration, the activated carbon may be exposed to an oxygen environment. Since the activated carbon is a combustible material, it may catch fire accidentally for some reason.

[0008] In order to reduce the safety risks as much as possible, the inventors of the present invention have studied the feasibility of using a cryopump with an alternative adsorbent material different from activated carbon. However, it is known that this alternative adsorbent material has a tendency to be easily affected by various factors such as the use environment and broken into powder compared to activated carbon. If the adsorbent material is damaged, the exhaust performance of the cryopump will be reduced. In addition, the broken powder may scatter and invade the components of the cryopump, thereby causing adverse effects on the components. For example, the powder of the adsorbent material may get stuck in a valve attached to or connected to the cryopump, causing valve leakage.

[0009] One of the exemplary objects of one embodiment of the present invention is to provide a new cryopump equipped with an alternative adsorbent for discharging non-condensable gas.

[0010] Means for solving technical problems

[0011] According to one embodiment of the present invention, a cryopump comprises: a cryopump housing; a cryopanel disposed in the cryopump housing and comprising a non-flammable adsorbent; a heating device for heating the non-flammable adsorbent and the cryopanel; a purge valve mounted on the cryopump housing and connecting the cryopump housing to a purge gas source; a roughing valve mounted on the cryopump housing and connecting the cryopump housing to a roughing pump; a sensor for generating a measurement signal indicating a temperature of the non-flammable adsorbent or an internal pressure of the cryopump housing; and a controller for receiving a regeneration start instruction and controlling at least one of the heating device, the purge valve and the roughing valve according to the measurement signal to execute either (i) a sublimation regeneration sequence or (ii) a dehydration sequence, wherein the sublimation regeneration sequence is configured to sublimate water from the non-flammable adsorbent by exposing the non-flammable adsorbent to a vacuum environment, and the dehydration sequence is configured to dehydrate the non-flammable adsorbent by exposing the non-flammable adsorbent to a dry environment having a pressure higher than the vacuum environment at room temperature or a temperature higher than the vacuum environment.

[0012] According to one embodiment of the present invention, a cryopump comprises: a cryopump housing; a cryopanel disposed in the cryopump housing and comprising a non-flammable adsorbent; a heating device for heating the non-flammable adsorbent and the cryopanel; a purge valve mounted on the cryopump housing and connecting the cryopump housing to a purge gas source; a roughing valve mounted on the cryopump housing and connecting the cryopump housing to a roughing pump; and a controller for controlling at least one of the heating device, the purge valve, and the roughing valve according to a dehydration sequence, and controlling the roughing valve to generate a vacuum environment in the cryopump housing after the dehydration sequence. The dehydration sequence is configured to dehydrate the non-flammable adsorbent by exposing the non-flammable adsorbent to a dry environment having a pressure higher than the vacuum environment at room temperature or a temperature higher than the room temperature.

[0013] According to one embodiment of the present invention, a cryogenic pump comprises: a non-flammable adsorbent material; and a controller, which sequentially performs the following steps to start the vacuum exhaust operation of the cryogenic pump: dehydrating the non-flammable adsorbent material by exposing it to a dry environment at room temperature or a temperature higher than room temperature; vacuum exhausting the surrounding environment of the non-flammable adsorbent material after dehydration of the non-flammable adsorbent material; and cooling the non-flammable adsorbent material to an ultra-low temperature in a vacuum environment.

[0014] According to one embodiment of the present invention, a method for starting operation of a cryogenic pump is provided. The cryogenic pump has a non-flammable adsorbent. The method for starting operation comprises the following steps: dehydrating the non-flammable adsorbent by exposing the non-flammable adsorbent to a dry environment at room temperature or a temperature higher than room temperature; after dehydrating the non-flammable adsorbent, vacuum exhausting the surrounding environment of the non-flammable adsorbent; and cooling the non-flammable adsorbent to an ultra-low temperature under a vacuum environment.

[0015] In addition, any combination of the above-mentioned constituent elements or any method, apparatus, system, etc. in which constituent elements or expressions of the present invention are replaced with each other may also be practiced as additional modes of the present invention.

[0016] Effects of the Invention

[0017] According to the present invention, it is possible to provide a new cryopump equipped with an alternative adsorbent for discharging non-condensable gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a diagram schematically showing a cryopump according to an embodiment.

[0019] Figure 2 This is a table showing representative physical properties of silica gel that can be used as a non-flammable adsorbent material for forming an adsorption region according to one embodiment.

[0020] Figure 3 This is a graph showing changes in the moisture absorption rate of silica gel due to heating.

[0021] Figure 4 This is a graph showing changes in the moisture absorption rate of silica gel according to the flow of purge gas.

[0022] Figure 5 This is a graph showing changes in the moisture absorption rate of silica gel in a low-pressure dry environment.

[0023] Figure 6 This is a flowchart illustrating a method for starting the operation of the cryopump according to the embodiment.

[0024] Figure 7 This is a block diagram of a cryopump according to an embodiment.

[0025] Figure 8 1 is a flowchart schematically showing a cryopump regeneration method according to an embodiment.

[0026] Fig. 9 Yes means Figure 8 Flow chart of the sublimation regeneration sequence shown.

[0027] Fig.10 Yes means Figure 8 Flow chart of the dehydration sequence shown.

[0028] Fig.11 Yes means Figure 8 FIG. 1 is a diagram showing an example of the change over time of temperature and pressure in the regeneration method shown.

[0029] Fig.12 It is a diagram schematically showing a cryopump system according to an embodiment. DETAILED DESCRIPTION

[0030] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in the following description, the same elements are marked with the same symbols, and repeated descriptions are appropriately omitted. Furthermore, the structures described below are only examples, and they do not limit the scope of the present invention in any way. Furthermore, for the sake of convenience of description, in the accompanying drawings referred to in the following description, the size or thickness of each component is appropriately set, which is not necessarily the actual size or ratio.

[0031] Figure 1 1 schematically shows a cryopump 10 according to an embodiment. The cryopump 10 is installed in a vacuum chamber of an ion implantation device, a sputtering device, an evaporation device, or other vacuum processing device, for example, and is used to increase the vacuum degree inside the vacuum chamber to a level required for a desired vacuum process. The cryopump 10 has an air inlet 12 for receiving a gas to be exhausted from the vacuum chamber. The gas enters an internal space 14 of the cryopump 10 through the air inlet 12.

[0032] In order to more easily understand the positional relationship between the components of the cryopump 10, the terms "axial direction" and "radial direction" are sometimes used below. The axial direction refers to the direction through the inlet 12 ( Figure 1 In the diagram, the direction along the central axis A) and the radial direction refers to the direction along the air inlet 12 (the direction perpendicular to the central axis A). For convenience, the side relatively close to the air inlet 12 in the axial direction is sometimes referred to as "upper", and the side relatively far from the air inlet 12 is sometimes referred to as "lower". That is, the side relatively far from the bottom of the cryopump 10 is sometimes referred to as "upper", and the side relatively close to the bottom of the cryopump 10 is sometimes referred to as "lower". Regarding the radial direction, the side close to the center of the air inlet 12 ( Figure 1 The side with the central axis A in the middle is called "inner", and the side close to the periphery of the air inlet 12 is called "outer". In addition, this expression has nothing to do with the configuration when the cryopump 10 is installed in the vacuum chamber. For example, the cryopump 10 can also be installed in the vacuum chamber in a manner that the air inlet 12 is downward in the vertical direction.

[0033] In addition, the direction around the axial direction may be referred to as a “circumferential direction.” The circumferential direction is a second direction along the air inlet 12 , and is a tangential direction orthogonal to the radial direction.

[0034] The cryopump 10 includes a refrigerator 16, a first cryopanel unit 18, a second cryopanel unit 20, and a cryopump housing 70. The first cryopanel unit 18 may also be referred to as a high temperature cryopanel section or a 100K section. The second cryopanel unit 20 may also be referred to as a low temperature cryopanel section or a 10K section.

[0035] The refrigerator 16 is, for example, an ultra-low temperature refrigerator such as a Gifford-McMahon refrigerator (so-called GM refrigerator). The refrigerator 16 is a two-stage refrigerator. Therefore, the refrigerator 16 has a first cooling stage 22 and a second cooling stage 24. The refrigerator 16 is configured to cool the first cooling stage 22 to a first cooling temperature and the second cooling stage 24 to a second cooling temperature. The second cooling temperature is a temperature lower than the first cooling temperature. For example, the first cooling stage 22 is cooled to about 65K to 120K, preferably cooled to 80K to 100K, and the second cooling stage 24 is cooled to about 10K to 20K. The first cooling stage 22 and the second cooling stage 24 may also be referred to as a high-temperature cooling stage and a low-temperature cooling stage, respectively.

[0036] Furthermore, the refrigerator 16 includes a refrigerator structure 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 section 26 of the refrigerator 16. Therefore, the refrigerator structure 21 includes a first cylinder 23 and a second cylinder 25 that extend coaxially in the radial direction. The first cylinder 23 connects the room temperature section 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 sequence.

[0037] A first displacer and a second displacer (not shown) capable of reciprocating are respectively arranged inside the first cylinder 23 and the second cylinder 25. A first cold storage device and a second cold storage device (not shown) are respectively assembled in the first displacer and the second displacer. In addition, the room temperature section 26 has a driving mechanism (not shown) for reciprocating the first displacer and the second displacer. The driving mechanism includes a flow path switching mechanism that switches the flow path of the working gas so as to periodically and repeatedly supply the working gas (for example, helium) to the inside of the refrigerator 16 and discharge the working gas from the inside of the refrigerator 16.

[0038] The refrigerator 16 is connected to a compressor (not shown) of a working gas. The refrigerator 16 expands the working gas pressurized by the compressor inside the refrigerator 16 to cool the first cooling stage 22 and the second cooling stage 24. The expanded working gas is returned to the compressor and re-pressurized. The refrigerator 16 generates cold by repeating a thermal cycle including supply and discharge of the working gas and reciprocating movement of the first displacer and the second displacer synchronized with the supply and discharge of the working gas.

[0039] The cryopump 10 shown in the figure is a so-called horizontal cryopump. A horizontal cryopump generally refers to a cryopump in which the refrigerator 16 is arranged to intersect (generally orthogonally intersect) the central axis A of the cryopump 10 .

[0040] The first cryopanel unit 18 includes a radiation shield 30 and an inlet cryopanel 32, which surround the second cryopanel unit 20. The first cryopanel unit 18 provides an ultra-low temperature surface for protecting the second cryopanel unit 20 from radiant heat from the outside of the cryopump 10 or the cryopump housing 70. The first cryopanel unit 18 is thermally connected to the first cooling stage 22. Therefore, the first cryopanel unit 18 is cooled to the first cooling temperature. There is a gap between the first cryopanel unit 18 and 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 also not in contact with the cryopump housing 70.

[0041] The first cryopanel unit 18 may also be referred to as a condensation cryopanel, and the second cryopanel unit 20 may also be referred to as an adsorption cryopanel.

[0042] The radiation shield 30 is provided to protect the second cryopanel unit 20 from radiant heat from the cryopump housing 70. The radiation shield 30 exists 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 gas inlet 12.

[0043] The radiation shield 30 includes: a shield front end 36 defining a shield main opening 34; a shield bottom 38 located on the side opposite to the shield main opening 34; and a shield side portion 40 connecting the shield front end 36 to the shield bottom 38. The shield side portion 40 extends axially from the shield front end 36 toward the side opposite to the shield main opening 34, and extends circumferentially to surround the second cooling stage 24.

[0044] The shield side portion 40 has a shield side portion opening 44 for inserting the refrigerator structure 21. The second cooling stage 24 and the second cylinder 25 are inserted into the radiation shield 30 from the outside of the radiation shield 30 through the shield side portion opening 44. The shield side portion opening 44 is a mounting hole formed in the shield side portion 40, and its shape is, for example, circular. The first cooling stage 22 is arranged outside the radiation shield 30.

[0045] The shield side portion 40 is provided with a mounting seat 46 for the refrigerator 16. The mounting seat 46 is a flat portion for mounting the first cooling stage 22 on the radiation shield 30, and is slightly concave when viewed from the outside of the radiation shield 30. The mounting seat 46 forms the outer periphery of the shield side opening 44. By mounting the first cooling stage 22 on the mounting seat 46, the radiation shield 30 is thermally connected to the first cooling stage 22.

[0046] In one embodiment, the radiation shield 30 may be thermally connected to the first cooling stage 22 via an additional heat transfer member, instead of directly attaching the radiation shield 30 to the first cooling stage 22 as described above.

[0047] In the illustrated embodiment, the radiation shield 30 is integrally formed into a cylindrical shape. Alternatively, the radiation shield 30 may be configured to be formed into a cylindrical shape as a whole by combining a plurality of components. These plurality of components may be arranged with gaps between them. For example, the radiation shield 30 may be divided into two parts in the axial direction.

[0048] The inlet cryopanel 32 is provided at the air inlet 12 (or the shielding member main opening 34, hereinafter the same) to protect the second cryopanel element 20 from radiant heat from a heat source outside the cryopump 10 (for example, a heat source in a vacuum chamber in which the cryopump 10 is installed). In addition, gas (for example, moisture) condensed at the cooling temperature of the inlet cryopanel 32 is captured on the surface of the inlet cryopanel 32.

[0049] The inlet cryopanel 32 is arranged at a position corresponding to the second cryopanel element 20 at the air inlet 12. The inlet cryopanel 32 occupies at least the central portion of the opening area of ​​the air inlet 12. The inlet cryopanel 32 has a planar structure that can be arranged at the air inlet 12. The inlet cryopanel 32 may have, for example, a louver or a herringbone plate formed in a concentric circle shape or a lattice shape, or may have a plate body in the form of a flat plate (for example, a circular plate).

[0050] The inlet cryopanel 32 is mounted to the shield front end 36 by a mounting member (not shown). In this way, the inlet cryopanel 32 is fixed to the radiation shield 30 and thermally connected to the radiation shield 30. The inlet cryopanel 32 is close to the second cryopanel unit 20 but not in contact with the second cryopanel unit 20.

[0051] The second cryopanel unit 20 is disposed 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 mounting member 62 extends axially upward and downward from the second cooling stage 24. The second cryopanel unit 20 is mounted on the second cooling stage 24 via the panel mounting member 62. Thus, 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.

[0052] A plurality of cryopanels 60 are arranged on the plate mounting member 62 along the direction from the shield main opening 34 toward the shield bottom 38 (i.e., along the central axis A). The plurality of cryopanels 60 are respectively flat plates (e.g., circular plates) extending in a direction perpendicular to the central axis A, and are mounted on the plate mounting member 62 in parallel with each other. In addition, the cryopanel 60 is not limited to a flat plate, and its shape is not particularly limited. For example, the cryopanel 60 may also have an inverted truncated cone or a truncated cone shape.

[0053] The plurality of cryopanels 60 may be Figure 1 The cryopanels 60 may have the same shape as shown, or may have different shapes (for example, different diameters). The shape of one of the cryopanels 60 may be the same as or larger than the shape of the cryopanel 60 adjacent to it above. Furthermore, the intervals between the cryopanels 60 may be as follows: Figure 1 The shown constants may also be different from each other.

[0054] In the second cryopanel unit 20, a non-flammable adsorbent material 64 is disposed on at least a portion of the surface. The non-flammable adsorbent material 64 is provided to capture non-condensable gas (e.g., hydrogen) by adsorption, and forms an adsorption region on the cryopanel 60. The adsorption region may be formed in a portion that becomes a shadow of the cryopanel 60 adjacent thereto, so that the adsorption region is not visible from the air inlet 12. For example, the adsorption region is formed in the entire region of the lower surface (back side) of the cryopanel 60. Furthermore, the adsorption region may also be formed in at least the center portion of the upper surface (front side) of the cryopanel 60.

[0055] The non-flammable adsorbent 64 may be a granular adsorbent, which can be bonded to the surface of the cryopanel 60 to form an adsorption region. The particle size of the adsorbent may be, for example, 2 mm to 5 mm. This facilitates bonding work during manufacturing.

[0056] In this embodiment, the non-combustible adsorbent 64 contains silica gel as a main component. The non-combustible adsorbent 64 may contain at least about 50% by mass of silica gel, or at least about 60% by mass of silica gel, or at least about 70% by mass of silica gel, or at least about 80% by mass of silica gel, or at least about 90% by mass of silica gel. The non-combustible adsorbent 64 may also be substantially all silica gel. Silica gel contains silicon dioxide as a main component, and therefore does not chemically react with oxygen.

[0057] In this way, the adsorption region is formed of a porous body composed of an inorganic substance, which does not contain organic substances. Unlike a typical cryopump, the cryopump 10 does not contain activated carbon.

[0058] Representative parameters related to the adsorption characteristics of porous bodies include average pore diameter, packing density, pore volume, and specific surface area. There are several types of silica gel that can be purchased, such as type A silica gel, type B silica gel, type N silica gel, type RD silica gel, and type ID silica gel. Therefore, Figure 2 The above four parameters of various types of silica gel are shown in FIG.

[0059] The inventors formed an adsorption region on the cryopanel 60 by bonding various types of granular silica gel to the cryopanel 60, and measured the amount of hydrogen adsorption under the same conditions. The results confirmed that more hydrogen was adsorbed in the A-type silica gel, the RD-type silica gel, and the N-type silica gel than in the B-type silica gel and the ID-type silica gel. The measurement results of the amount of hydrogen adsorption per unit area of ​​the adsorption region for the A-type silica gel, the N-type silica gel, and the RD-type silica gel are as follows.

[0060] Type A silica gel: 251(L / m 2 )

[0061] RD type silica gel: 195 (L / m 2 )

[0062] N type silica gel: 179 (L / m 2 )

[0063] Therefore, it is considered that type A silica gel, type RD silica gel, and type N silica gel are suitable as adsorbents for non-condensable gases used in the cryopump 10. Type B silica gel and type ID silica gel may also be used as adsorbents for non-condensable gases in applications requiring a relatively low storage amount.

[0064] The following two reasons indicate that the smaller the average pore diameter of the adsorbent, the greater the amount of non-condensable gas adsorbed by the adsorbent. The first reason is that the smaller the pore diameter, the greater the number of pores per unit area on the surface of the adsorbent. As a result, the surface area for gas adsorption increases, and gas molecules become easier to adsorb.

[0065] Furthermore, adsorption is caused by the physical interaction (e.g., intermolecular force) between the surface of the adsorbent material and the gas molecules. The smaller the diameter of the pore, the closer the size of the pore is to the size of the gas molecule. In this way, when the gas molecules enter the pore, the possibility that the inner wall of the pore exists within the distance range centered on the gas molecule that can produce interaction becomes higher. The interaction between the gas molecules and the wall of the pore becomes easier to occur, and the gas molecules become easier to be adsorbed. This is the second reason.

[0066] According to this view, in order to obtain good non-condensable gas adsorption characteristics, silica gel preferably has an average pore diameter of 3.0 nm or less. In addition, the size of a hydrogen molecule is approximately 0.1 nm, so silica gel preferably has an average pore diameter larger than that (for example, an average pore diameter of 0.5 nm or more).

[0067] The silica gel more preferably has an average pore diameter of 2.0 nm to 3.0 nm. Figure 2 It can be seen that type A silica gel, type RD silica gel and type N silica gel have average pore diameters within the preferred range, while type B silica gel and type ID silica gel have average pore diameters far larger than the range.

[0068] If the average pore diameters of type A silica gel, RD type silica gel and N type silica gel are compared, the average pore diameter of type A silica gel is larger than the average pore diameters of the other two types of silica gel. However, as mentioned above, the hydrogen absorption capacity per unit area of ​​type A silica gel is larger than the hydrogen absorption capacity per unit area of ​​the other two types of silica gel. In this way, the reason why type A silica gel can obtain good results is because type A silica gel is easier to obtain granular silica gel with uniform shape. Uniform granular silica gel is easy to be tightly arranged and bonded to the surface of the cryopanel. Therefore, compared with irregularly shaped granular silica gel, type A silica gel can be arranged on the cryopanel 60 with high density, thereby increasing the absorption capacity.

[0069] In addition to the average pore diameter within the above range, the silica gel preferably has a packing density of 0.7 to 0.9 g / mL, a pore volume of 0.25 to 0.45 mL / g, and a micropore volume of 550 to 750 m 2 If silica gel having such physical properties is used, it can be expected to have good adsorption characteristics similar to those of type A silica gel, type RD silica gel and type N silica gel.

[0070] A condensation region 66 for capturing condensable gas by condensation is formed on at least a portion of the surface of the second cryopanel unit 20. The condensation region 66 is, for example, a region on the surface of the cryopanel to which the adsorbent material is not adhered, and the surface of the cryopanel substrate (for example, a metal surface) is exposed. For example, the outer peripheral portion of the upper surface of the cryopanel 60 may be the condensation region 66.

[0071] The cryopump housing 70 is a housing of the cryopump 10 that accommodates the first cryopanel unit 18, the second cryopanel unit 20, and the refrigerator 16, and is a vacuum container configured to maintain the vacuum tightness of the internal space 14. The cryopump housing 70 surrounds the first cryopanel unit 18 and the refrigerator structure 21 in a non-contact manner. The cryopump housing 70 is mounted on the room temperature section 26 of the refrigerator 16.

[0072] The front end of the cryopump housing 70 defines the inlet port 12. The cryopump housing 70 includes an inlet port flange 72 extending radially outward from the front end thereof. The inlet port flange 72 is provided over the entire circumference of the cryopump housing 70. The cryopump 10 is mounted on a vacuum chamber to be evacuated using the inlet port flange 72.

[0073] A roughing valve 80 , a purge valve 84 , and an exhaust valve 88 are mounted on the cryopump housing 70 .

[0074] The roughing valve 80 is connected to the roughing pump 82. By opening and closing the roughing valve 80, the roughing pump 82 is connected to or disconnected from the cryopump 10. By opening the roughing valve 80, the roughing pump 82 is connected to the cryopump housing 70, and by closing the roughing valve 80, the roughing pump 82 is disconnected from the cryopump housing 70. By opening the roughing valve 80 and operating the roughing pump 82, the inside of the cryopump 10 can be depressurized.

[0075] The roughing pump 82 is a vacuum pump for evacuating the cryopump 10. The roughing pump 82 is a vacuum pump for providing the cryopump 10 with a low vacuum region of the operating pressure range of the cryopump 10, in other words, providing the operating start pressure (i.e., the base pressure level) of the cryopump 10. The roughing pump 82 is capable of reducing the pressure of the cryopump housing 70 from atmospheric pressure to the base pressure level. The base pressure level is equivalent to the high vacuum region of the roughing pump 82, which is included in the overlapping portion of the operating pressure range of the roughing pump 82 and the cryopump 10. The base pressure level is, for example, a range of greater than 1 Pa and less than 50 Pa (for example, about 10 Pa).

[0076] Typically, the roughing pump 82 is provided as another vacuum device different from the cryopump 10, for example, constituting a part of a vacuum system including a vacuum chamber connected to the cryopump 10. The cryopump 10 is a main pump of the vacuum chamber, and the roughing pump 82 is an auxiliary pump.

[0077] The purge valve 84 is connected to a purge gas supply device including a purge gas source 86. By opening and closing the purge valve 84, the purge gas source 86 is connected to or disconnected from the cryopump 10, thereby controlling the supply of the purge gas to the cryopump 10. By opening the purge valve 84, the purge gas is allowed to flow from the purge gas source 86 to the cryopump housing 70. By closing the purge valve 84, the purge gas is cut off from flowing from the purge gas source 86 to the cryopump housing 70. By opening the purge valve 84, the purge gas is introduced from the purge gas source 86 into the cryopump housing 70, so that the internal pressure of the cryopump 10 can be increased. The supplied purge gas is discharged from the cryopump 10 through the roughing valve 80.

[0078] The temperature of the purge gas is adjusted to room temperature, for example. However, in one embodiment, the purge gas may be a gas heated to a temperature higher than room temperature, or a gas slightly lower than room temperature. In this specification, room temperature is a temperature selected from the range of 10° C. to 30° C. or the range of 15° C. to 25° C., for example, about 20° C. The purge gas is, for example, nitrogen. The purge gas may also be a dry gas.

[0079] The exhaust valve 88 is provided to discharge fluid from the interior of the cryopump 10 to the external environment. The exhaust valve 88 is usually closed, but can be mechanically opened based on the pressure difference between the external pressure and the internal pressure of the cryopump housing 70. By opening the exhaust valve 88, the positive pressure generated inside the cryopump housing 70 can be released to the outside. The fluid discharged from the exhaust valve 88 is basically a gas, but it can also be a liquid or a gas-liquid mixture.

[0080] The cryopump 10 is provided with a heating device for heating the non-flammable adsorbent material 64 and the cryopanel 60. The heating device is, for example, a refrigerator 16. The refrigerator 16 can perform a temperature increase operation (so-called reverse temperature increase). That is, the refrigerator 16 is configured as follows: when the driving mechanism provided in the room temperature section 26 moves in the opposite direction to the cooling operation, the working gas is adiabatically compressed. The refrigerator 16 heats the first cooling stage 22 and the second cooling stage 24 by the compression heat thus obtained. The first cryopanel unit 18 and the second cryopanel unit 20 are heated using the first cooling stage 22 and the second cooling stage 24 as heat sources, respectively.

[0081] In the case of supplying heated purge gas, the purge valve 84 can be regarded as constituting a part of the heating device. Alternatively, a heating device such as an electric heater can be provided in the cryopump 10. For example, an electric heater that can be independently controlled relative to the operation of the refrigerator 16 can be installed on the first cooling stage 22 and / or the second cooling stage 24 of the refrigerator 16.

[0082] The cryopump 10 includes a first temperature sensor 90 for measuring the temperature of the first cooling stage 22 and a second temperature sensor 92 for measuring the temperature of the second cooling stage 24. The first temperature sensor 90 is mounted on the first cooling stage 22. The second temperature sensor 92 is mounted on the second cooling stage 24. Therefore, the first temperature sensor 90 can measure the temperature of the first cryopanel unit 18, and the second temperature sensor 92 can measure the temperature of the second cryopanel unit 20. The temperature measured by the second temperature sensor 92 can be regarded as indicating the temperature of the non-flammable adsorbent 64. Furthermore, when the temperature of the entire cryopump 10 is uniform (e.g., room temperature) as before the start of operation of the cryopump 10, the temperature measured by the first temperature sensor 90 can be regarded as indicating the temperature of the non-flammable adsorbent 64.

[0083] Furthermore, a pressure sensor 94 is provided inside the cryopump housing 70 . The pressure sensor 94 is provided, for example, outside the first cryopanel unit 18 and near the refrigerator 16 . The pressure sensor 94 can measure the internal pressure of the cryopump housing 70 .

[0084] The cryopump 10 includes a controller 100 that controls the operation (eg, vacuum pumping operation, regeneration operation, etc.) of the cryopump 10. The controller 100 may also be referred to as a cryopump controller or a regeneration controller.

[0085] The controller 100 is configured to be able to execute a dehydration sequence (hereinafter also referred to as a basic dehydration sequence) for drying the non-flammable adsorbent 64 (details will be described later). The dehydration sequence is configured to expose the non-flammable adsorbent 64 to a dry environment with a pressure higher than the vacuum environment (for example, at least 1000 Pa) at room temperature or a higher temperature so as to dehydrate the non-flammable adsorbent 64. The controller 100 controls at least one of the heating device, the purge valve 84, and the roughing valve 80 according to the dehydration sequence. The controller 100 controls the roughing valve 80 to generate a vacuum environment (for example, less than 100 Pa) in the cryopump housing 70 after the dehydration sequence. The controller 100 controls the refrigerator 16 to provide ultra-low temperature cooling in the vacuum environment.

[0086] As mentioned at the beginning of this manual, typical cryopumps in the past used activated carbon as an adsorbent material, and in certain applications, gases containing oxygen or ozone are exhausted by the cryopump. In this case, during regeneration, the activated carbon is exposed to an oxygen environment. Since activated carbon is a combustible material, it may be affected by certain factors and accidentally catch fire. In order to reduce the possibility of accidents, it is very important to avoid the coexistence of multiple dangerous factors.

[0087] According to the embodiment, the cryopump 10 has a non-flammable adsorbent material 64, so that even if oxygen is present, the adsorbent material can be reliably prevented from catching fire and burning. Unlike in the past, the coexistence of multiple dangerous factors (activated carbon and oxygen) can be avoided, thereby eliminating the risk of fire. Therefore, the safety of the cryopump 10 is improved. A cryopump 10 suitable for use in which oxygen is contained in the gas to be discharged can be provided.

[0088] The non-combustible adsorbent 64 is not limited to silica gel. Other inorganic porous materials such as molecular sieves can also be used as the non-combustible adsorbent 64. As long as it is an inorganic adsorbent, safety is also improved.

[0089] If silica gel is used as in the present embodiment, there is an advantage that the cryopump 10 can be easily regenerated. The adsorption characteristics of a porous body are generally temperature-dependent, that is, the higher the temperature, the lower the adsorption amount. In other words, if the porous body is heated, the gas adsorbed on the porous body becomes easy to be released. Compared with other inorganic porous bodies, the adsorption characteristics of silica gel at high temperatures decrease significantly. Therefore, the non-combustible adsorbent 64 containing silica gel is easy to regenerate.

[0090] However, when the cryopump 10 is shipped from the manufacturer, it is delivered to the user in a state where a cover is installed on the air inlet 12. The cryopump 10 can be filled with nitrogen or other clean dry gases. The cryopump 10 delivered to the user is stored in a state where the cover is covered. The user removes the cover from the air inlet 12 at the site where the cryopump 10 is used and installs the cryopump 10 in a vacuum chamber. Afterwards, the roughing pump 82 vacuum-draws the cryopump 10 to a base pressure (for example, a small pressure less than 100 Pa) through the roughing valve 80, and the refrigerator 16 starts cooling operation. The first cryopanel unit 18 and the second cryopanel unit 20 are cooled to ultra-low temperatures, and the cryopump 10 starts vacuum exhaust operation.

[0091] If the user does not properly store the cryopump 10 (leave it in a state where the cover is removed from the cryopump 10, etc.), the non-combustible adsorbent 64 will be exposed to the atmosphere for a long time and may absorb a large amount of moisture. If the non-combustible adsorbent 64 is exposed to the atmosphere for a long time due to improper storage, the moisture absorption rate (mass ratio, for example, the amount of water absorbed per 1g of the non-combustible adsorbent 64) of the non-combustible adsorbent 64 may reach at least 30%.

[0092] The present inventors have found that when the cryopump 10 is evacuated to start operation under such circumstances, a hitherto unknown phenomenon occurs, such as the non-flammable adsorbent 64 immediately breaking into powder. This phenomenon does not occur in conventional cryopumps having activated carbon as the adsorbent.

[0093] This is a problem. If the non-flammable adsorbent material 64 is damaged, the exhaust performance of the non-condensable gas of the cryopump will be reduced. In addition, if the crushed powder of the non-flammable adsorbent material 64 gets stuck in the roughing valve 80 and the purge valve 84 and other valves attached to the cryopump 10 or connected to the cryopump 10, it may cause valve leakage. If the roughing valve 80 and the purge valve 84 leak, the vacuum cannot be maintained inside the cryopump 10, and maintenance such as valve replacement is required. The crushed powder may also invade other components of the cryopump 10 such as sensors and have an adverse effect on the components.

[0094] It is believed that the mechanism of this new phenomenon is as follows: the area around the non-combustible adsorbent 64 is rapidly depressurized by vacuum suction, causing moisture to rapidly vaporize and escape from the non-combustible adsorbent 64, resulting in local cooling and thermal stress inside the adsorbent, resulting in the destruction of the non-combustible adsorbent 64. This crushing is significant when the non-combustible adsorbent 64 is made of silica gel, but other inorganic adsorbents (such as zeolite, etc.) may also cause this crushing based on the same mechanism.

[0095] The inventors have found through experiments that as long as the moisture absorption rate of the non-combustible adsorbent 64 is set to less than 24% (preferably less than 20%), the crushing of the non-combustible adsorbent 64 caused by vacuum suction can be prevented. Therefore, in the embodiment, the cryopump 10 is configured to execute a dehydration sequence for drying the non-combustible adsorbent 64 in order to start the vacuum exhaust operation of the cryopump 10. The drying condition is set to reduce the moisture absorption rate of the non-combustible adsorbent 64 to less than 24% (preferably less than 20%). The drying condition may include at least one of the heating temperature, the pressure of the drying environment, and the drying time.

[0096] Figure 3 This is a graph showing the change in moisture absorption rate of silica gel based on heating. This graph is the result obtained by the inventor through experiments. Figure 3 The graph depicts the change in moisture absorption over time when silica gel is heated to a specified drying temperature using a drying furnace. The initial moisture absorption was set to 30%, which simulates the state where silica gel installed in a cryopump is exposed to the atmosphere for a long time and absorbs a large amount of moisture. The test was conducted at three drying temperatures of 80°C, 60°C, and 50°C under atmospheric pressure.

[0097] Regardless of the drying temperature, the moisture absorption rate will decrease over time as the water is separated from the silica gel. The higher the drying temperature, the faster the moisture absorption rate decreases. At a drying temperature of 80°C, the moisture absorption rate decreases to about 24% in about 20 to 25 minutes from the start of drying, and to about 20% in about 35 to 40 minutes. At a drying temperature of 60°C, the moisture absorption rate decreases to about 24% in about 50 minutes, and to about 20% in about 90 minutes. At a drying temperature of 50°C, the moisture absorption rate decreases to about 24% in about 140 minutes, and to about 20% in about 250 minutes.

[0098] Therefore, from the experimental results, it can be seen that the dehydration of silica gel is effective when the drying temperature is set to a minimum of 50°C. The shorter the drying time, the more practical it is. As long as the drying temperature is set to a minimum of 60°C, the moisture absorption rate can be reduced to less than about 24% within a drying time of about 1 hour. And, as long as the drying temperature is set to a minimum of 80°C, the moisture absorption rate can be reduced to less than about 24% within a drying time of about 30 minutes.

[0099] Therefore, the drying temperature (target heating temperature) of the non-combustible adsorbent material 64 can be a temperature higher than room temperature (for example, above 30°C or above 40°C), preferably, it can be a minimum of 50°C (for example, above 60°C or above 70°C), and more preferably, it can be a minimum of 80°C (for example, above 90°C).

[0100] If the drying temperature is set too high, there is a risk of exceeding the heat resistance temperature of the cryopump 10. Therefore, the drying temperature may be 130°C or lower, or 120°C or lower, or 110°C or lower, or 100°C or lower, or 95°C or lower.

[0101] Figure 4 This is a graph showing the change in the moisture absorption rate of silica gel based on the flow of purge gas. This graph is also the result obtained by the inventor through experiments. Figure 4 The time-dependent change in moisture absorption when the silica gel is dried by supplying purge gas to the container at a specified purge gas flow rate is depicted. The purge gas is dry nitrogen. The initial moisture absorption rate is 30%. The test was conducted under non-heating conditions (i.e., room temperature) at three purge gas flow rates of 90 SLM (standard liter / min), 44 SLM, and 28 SLM.

[0102] Regardless of the purge gas flow rate, the moisture absorption rate decreases over time as the water is removed from the silica gel. The higher the purge gas flow rate, the faster the moisture absorption rate decreases. Figure 4 As shown in the figure, for example, when the purge gas flow rate is 90 SLM, the moisture absorption rate decreases to about 24% in about 40 minutes and to about 20% in about 70 minutes. From this experimental result, it can be seen that the supply of purge gas is effective for dehydrating silica gel. No heating is required for dehydration, and only the supply of purge gas is sufficient.

[0103] Figure 5 This is a graph showing the change in the moisture absorption rate of silica gel in a low-pressure dry environment. This graph is the result obtained by the inventor through experiments. Figure 5 Graphs are plotted showing the time-dependent change in moisture absorption when silica gel is kept in a low-pressure dry environment of 1000 to 1100 Pa. Similarly, the initial moisture absorption is 30%. Neither purge gas is supplied to the dry environment, nor is heating performed.

[0104] By setting the dry environment to a pressure lower than atmospheric pressure, the moisture absorption rate decreases over time, and water is removed from the silica gel. Figure 5As shown in the figure, under the low pressure dry environment of 1000-1100 Pa, the moisture absorption rate decreased to about 24% in about 200 minutes and to about 20% in about 400 minutes. At this time, no silica gel was found to be broken. From the experimental results, it can be known that setting the dry environment to a lower pressure than the atmospheric pressure is effective for dehydrating silica gel. The pressure of the dry environment can be, for example, at least 1000 Pa, or at least 0.1 atmosphere, or at least 1 atmosphere.

[0105] Figure 6 1 is a flowchart illustrating a method for starting operation of the cryopump 10 according to the embodiment. The method includes a step (S10) of dehydrating the non-combustible adsorbent 64 by exposing the non-combustible adsorbent 64 to a dry environment at room temperature or higher. As described above, the drying condition is set so that the moisture absorption rate of the non-combustible adsorbent 64 is reduced to less than 24% (preferably less than 20%).

[0106] The dehydration process of the non-combustible adsorbent 64 includes the step of forming a dry environment around the non-combustible adsorbent 64 by at least one of the following steps: heating the non-combustible adsorbent 64 to a drying temperature higher than room temperature (e.g., 50° C. or higher or 80° C. or higher); supplying a purge gas to the cryopump housing 70; and maintaining the cryopump housing 70 at a pressure higher than 1000 Pa (e.g., a pressure higher than atmospheric pressure). The non-combustible adsorbent 64 is heated by a heating device (e.g., reverse heating of the refrigerator 16, supply of a high-temperature purge gas, or operation of an electric heater provided in the refrigerator 16 or the cryopanel 60). The purge valve 84 controls the supply of the purge gas. The roughing valve 80 controls the decompression of the cryopump housing 70.

[0107] After the non-combustible adsorbent 64 is dehydrated (S10), the surrounding environment of the non-combustible adsorbent 64 is evacuated (S20). The roughing valve 80 is opened to operate the roughing pump 82. The roughing pump 82 roughly evacuates the cryopump housing 70 to the base pressure through the roughing valve 80. As described above, the base pressure is, for example, less than 100 Pa. A vacuum environment is formed around the non-combustible adsorbent 64.

[0108] The non-flammable adsorbent material 64 is cooled to an ultra-low temperature under a vacuum environment (S30). The refrigerator 16 starts cooling operation, and the first cooling stage 22 and the second cooling stage 24 are cooled to the first cooling temperature and the second cooling temperature, respectively. Therefore, the first cryopanel unit 18 and the second cryopanel unit 20, which are thermally connected to the first cooling stage 22 and the second cooling stage 24, are also cooled to the first cooling temperature and the second cooling temperature, respectively. The non-flammable adsorbent material 64 is arranged in the second cryopanel unit 20, so the non-flammable adsorbent material 64 is also cooled to the second cooling temperature.

[0109] The controller 100 according to the embodiment is configured to execute Figure 6 The method for starting the operation of the cryopump 10 is shown. In order to start the vacuum exhaust operation of the cryopump 10, the controller 100 is configured to sequentially perform the following steps: (a) exposing the non-combustible adsorbent 64 to a dry environment at room temperature or a temperature higher than room temperature to dehydrate the non-combustible adsorbent 64; (b) after dehydrating the non-combustible adsorbent 64, vacuum exhausting the surrounding environment of the non-combustible adsorbent 64; and (c) cooling the non-combustible adsorbent 64 to an ultra-low temperature in a vacuum environment.

[0110] In this way, the cryopump 10 starts vacuum exhaust operation. The inlet cryopanel 32 cools the gas that flies from the vacuum chamber toward the cryopump 10. The vapor pressure is sufficiently reduced at the first cooling temperature (for example, 10 -8 Pa or less) condenses on the surface of the inlet cryopanel 32. This gas may also be referred to as the first gas. The first gas is, for example, water vapor. In this way, the inlet cryopanel 32 can discharge the first gas. A portion of the gas whose vapor pressure is not sufficiently reduced at the first cooling temperature enters the internal space 14 from the air inlet 12. Or another portion of the gas is reflected by the inlet cryopanel 32 and does not enter the internal space 14.

[0111] The gas entering the internal space 14 is cooled by the second cryopanel unit 20. The gas whose vapor pressure is sufficiently reduced at the second cooling temperature (e.g., 10 -8 Pa or less) condenses on the surface of the second cryopanel unit 20. This gas may also be referred to as a second gas. The second gas is, for example, argon. In this way, the second cryopanel unit 20 can discharge the second gas.

[0112] The gas whose vapor pressure is not sufficiently reduced at the second cooling temperature is absorbed by the adsorbent material of the second cryopanel unit 20. This gas may also be referred to as a third gas. The third gas is referred to as a non-condensable gas, such as hydrogen. In this way, the second cryopanel unit 20 can discharge the third gas. Thus, the cryopump 10 can discharge various gases by condensation or adsorption, thereby enabling the vacuum degree of the vacuum chamber to reach a desired level.

[0113] By continuing the exhaust operation, gas will gradually accumulate in the cryopump 10. In order to exhaust the accumulated gas to the outside, the cryopump 10 needs to be regenerated. It is not uncommon for the gas exhausted by the cryopump to contain water vapor. During the vacuum exhaust operation of the cryopump 10, water vapor condenses on the first cryopanel unit 18 and turns into ice. During regeneration, the cryopump 10 is heated to room temperature or a higher temperature (for example, 290K to 330K), so the ice melts into water. There is a possibility that water droplets will appear on the adsorbent material.

[0114] Silica gel is a type of hydrophilic material having an OH group. If this hydrophilic adsorbent material comes into contact with liquid water, hydrogen bonds are easily formed between the molecules of the adsorbent material and the water molecules. Hydrogen bonds are strong bonds, so it takes a long time to dehydrate the adsorbent material, and it can be expected that the regeneration time will be longer. This is not desirable. In addition, silica gel has the property of becoming brittle when immersed in liquid water and then naturally breaking. Therefore, in the case where the non-flammable adsorbent 64 contains silica gel, it is particularly desirable to avoid contact with liquid water. In addition, activated carbon, which has been frequently used in the past, is a hydrophobic material, unlike silica gel.

[0115] Therefore, the regeneration of the cryopump 10 can sublime the ice so that it can be directly gasified into water vapor without passing through liquid water and discharged to the outside. An embodiment in which the dehydration sequence of the non-flammable adsorbent 64 is combined with such sublimation regeneration will be described below.

[0116] Figure 7 It is a block diagram of a cryopump 10 according to an embodiment.

[0117] The first temperature sensor 90 periodically measures the temperature of the first cryopanel unit 18 and generates a first temperature measurement signal S1 indicating the measured temperature of the first cryopanel unit 18. The first temperature sensor 90 is connected to the controller 100 for communication and outputs the first temperature measurement signal S1 to the controller 100. The second temperature sensor 92 periodically measures the temperature of the second cryopanel unit 20 and generates a second temperature measurement signal S2 indicating the measured temperature of the second cryopanel unit 20. The second temperature sensor 92 is connected to the controller 100 for communication and outputs the second temperature measurement signal S2 to the controller 100.

[0118] The pressure sensor 94 regularly measures the internal pressure of the cryopump housing 70 and generates a pressure measurement signal S3 indicating the internal pressure of the cryopump housing 70. The pressure sensor 94 is communicatively connected to the controller 100 and outputs the pressure measurement signal S3 to the controller 100.

[0119] The controller 100 is configured to receive the first temperature measurement signal S1, the second temperature measurement signal S2, and the pressure measurement signal S3. The controller 100 is configured to generate at least one of a refrigerator control signal S4, a roughing valve control signal S5, and a purge valve control signal S6 based on at least one of the first temperature measurement signal S1, the second temperature measurement signal S2, and the pressure measurement signal S3. The controller 100 is configured to send the refrigerator control signal S4 to the refrigerator 16, send the roughing valve control signal S5 to the roughing valve 80, and send the purge valve control signal S6 to the purge valve 84.

[0120] The refrigerator 16 is controlled according to the refrigerator control signal S4. The opening and closing of the cooling operation or the opening and closing of the reverse heating operation of the refrigerator 16, and the switching between the cooling operation and the reverse heating operation are based on the refrigerator control signal S4. In addition, the operating frequency of the refrigerator 16 (corresponding to the rotation speed of the motor driving the refrigerator 16) can be controlled to be variable according to the refrigerator control signal S4. The roughing valve 80 opens or closes according to the roughing valve control signal S5. The purge valve 84 opens or closes according to the purge valve control signal S6. In addition, the controller 100 can control the heating device (for example, an electric heater installed in the refrigerator 16) by switching the opening and closing of the heating device provided in the cryopump 10.

[0121] The cryopump 10 includes a storage unit 102, an input unit 104, and an output unit 106. The storage unit 102 is configured to store data related to the control of the cryopump 10. The storage unit 102 may be a semiconductor memory or other data storage medium. The input unit 104 is configured to receive input from a user or other device. The input unit 104 includes, for example, an input mechanism such as a mouse or keyboard for receiving input from a user and / or a communication mechanism for communicating with other devices. The output unit 106 is configured to output data related to the control of the cryopump 10, and includes an output mechanism such as a display or a printer. The storage unit 102, the input unit 104, and the output unit 106 are respectively connected to the controller 100 for communication.

[0122] The controller 100 includes a sublimation regeneration unit 110 and a dehydration unit 112. The sublimation regeneration unit 110 is configured to execute a sublimation regeneration sequence based on a first temperature measurement signal S1, a second temperature measurement signal S2, and a pressure measurement signal S3. The dehydration unit 112 is configured to execute a dehydration sequence based on a first temperature measurement signal S1, a second temperature measurement signal S2, and a pressure measurement signal S3. The sublimation regeneration unit 110 may be referred to as a sublimation regeneration controller, and the dehydration unit 112 may be referred to as a dehydration controller.

[0123] The controller 100 is configured to receive the regeneration start command S7 and start regeneration of the cryopump 10. The regeneration start command S7 is input to the controller 100 from the input unit 104, for example.

[0124] The controller 100 can be implemented in hardware by components or circuits represented by a CPU or memory of a computer, and in software by a computer program, etc. Figure 7 The functional blocks implemented by their cooperation are appropriately shown in the figure. It should be understood by those skilled in the art that these functional blocks can be implemented in various forms by a combination of hardware and software.

[0125] For example, the controller 100 can be implemented by a combination of a processor (hardware) such as a CPU (Central Processing Unit), a microcomputer, and a software program executed by the processor (hardware). Such a hardware processor can be composed of a programmable logic component such as an FPGA (Field Programmable Gate Array), or a control circuit such as a programmable logic controller (PLC). The software program can be a computer program for causing the controller 100 to execute a regeneration sequence (e.g., a sublimation regeneration sequence, a dehydration sequence) of the cryopump 10.

[0126] Figure 8 1 is a flowchart schematically showing a cryopump regeneration method according to an embodiment. The cryopump regeneration method is executed by a controller 100. The controller 100 receives a regeneration start instruction S7, and controls the refrigerator 16, the purge valve 84, and the roughing valve 80 as a heating device according to a temperature measurement signal (e.g., at least one of the first temperature measurement signal S1 and the second temperature measurement signal S2) indicating the temperature of the non-flammable adsorbent 64, thereby executing either a sublimation regeneration sequence or a dehydration sequence. The sublimation regeneration sequence is configured to expose the non-flammable adsorbent 64 to a vacuum environment so that water sublimates from the non-flammable adsorbent 64. The dehydration sequence is configured to expose the non-flammable adsorbent 64 to a dry environment with a pressure higher than the vacuum environment at room temperature or a temperature higher than the vacuum environment, thereby dehydrating the non-flammable adsorbent 64.

[0127] If the regeneration start command S7 is received, Figure 8 As shown, the controller 100 determines whether the measured temperature of the first cryopanel unit 18 (i.e., the first measured temperature T1) is lower than the first reference temperature Tr1 based on the first temperature measurement signal S1 (S51). Furthermore, the controller 100 determines whether the measured temperature of the second cryopanel unit 20 (i.e., the second measured temperature T2) is lower than the second reference temperature Tr2 based on the second temperature measurement signal S2 (S52).

[0128] The purpose of these temperature determinations is to grasp the state of the cryopump 10 before receiving the regeneration start instruction S7. When the vacuum exhaust operation of the cryopump 10 is in progress, the first cryopanel unit 18 and the second cryopanel unit 20 are cooled to an ultra-low temperature. On the other hand, when the vacuum exhaust operation is to be started after the cryopump 10 is newly installed in the vacuum chamber, the cryopump 10 is at room temperature. Alternatively, when it takes a long time to recover after a power outage or other abnormal conditions, the cryopump 10 will also naturally heat up from an ultra-low temperature to room temperature. Therefore, in order to distinguish whether the cryopump 10 is cooled to an ultra-low temperature or at room temperature, the first reference temperature Tr1 and the second reference temperature Tr2 can be set to temperature values ​​of, for example, 250K to 280K, for example, can be set to 273K. Here, the first reference temperature Tr1 and the second reference temperature Tr2 are set to the same value, but can also be set to different values.

[0129] If the first measured temperature T1 is lower than the first reference temperature Tr1 and the second measured temperature T2 is lower than the second reference temperature Tr2 (Yes in S51 and Yes in S52), it can be considered that the controller 100 has performed the vacuum evacuation operation of the cryopump 10 until receiving the regeneration start instruction S7. Therefore, in this case, the sublimation regeneration unit 110 of the controller 100 executes the sublimation regeneration sequence (S100).

[0130] On the other hand, if the first measured temperature T1 is higher than the first reference temperature Tr1 or the second measured temperature T2 is higher than the second reference temperature Tr2 (No in S51 or No in S52), the cryopump 10 can be regarded as being at room temperature. Therefore, in this case, the dehydration unit 112 of the controller 100 executes the dehydration sequence (S200). After the dehydration sequence, the sublimation regeneration unit 110 of the controller 100 executes the sublimation regeneration sequence (S100). In this way, the regeneration of the cryopump 10 is terminated. If the regeneration is terminated, the cryopump 10 starts the vacuum exhaust operation.

[0131] In this way, the controller 100 controls at least one of the heating device, the purge valve 84, and the roughing valve 80 based on the temperature measurement signal indicating the temperature of the non-combustible adsorbent 64, thereby executing the dehydration sequence when the non-combustible adsorbent 64 is regarded as being at room temperature. In addition, the controller 100 controls at least one of the heating device, the purge valve 84, and the roughing valve 80 based on the temperature measurement signal indicating the temperature of the non-combustible adsorbent 64, thereby executing the sublimation regeneration sequence when the non-combustible adsorbent 64 is regarded as being at a temperature lower than room temperature.

[0132] In addition, the controller 100 can control the refrigerator 16, the purge valve 84 or the roughing valve 80 as a heating device according to the pressure measurement signal S3 after receiving the regeneration start instruction S7, thereby executing any one of the sublimation regeneration sequence or the dehydration sequence. When the vacuum exhaust operation of the cryopump 10 is in progress, the interior of the cryopump housing 70 is in a vacuum state. On the other hand, when the vacuum exhaust operation is to be started after the cryopump 10 is newly set in the vacuum chamber, the interior of the cryopump housing 70 is in an atmospheric pressure state. Alternatively, in the case where it takes a long time to recover after a power outage or other abnormal conditions, the interior of the cryopump housing 70 will also be pressurized from vacuum to atmospheric pressure (or above) due to the regasification of the captured gas. Therefore, the state of the cryopump 10 can be grasped from the internal pressure of the cryopump housing 70.

[0133] Alternatively, the controller 100 may control at least one of the heating device, the purge valve, and the roughing valve according to the state of the cryopump 10 just before the regeneration start instruction S7 is received instead of the measurement signal from the sensor, thereby executing either the sublimation regeneration sequence or the dehydration sequence. The controller 100 may also be configured to generate state data indicating the current state of the cryopump 10 (e.g., in vacuum exhaust operation, newly set, regenerated, etc.) and save it to the storage unit 102. The controller 100 may also select the sublimation regeneration sequence when the state data before the regeneration start instruction S7 is received indicates vacuum exhaust operation, and select the dehydration sequence when the state data before the regeneration start instruction S7 is received indicates new setting.

[0134] In this way, when the dehydration sequence is not necessary, the dehydration sequence can be omitted, thereby preventing the regeneration time from being prolonged.

[0135] Fig. 9 Yes means Figure 8 Flow chart of the sublimation regeneration sequence shown in FIG. 1. If the sublimation regeneration sequence starts, the sublimation regeneration unit 110 opens the purge valve 84 and closes the roughing valve 80 (S101). The purge gas is supplied to the cryopump housing 70 from the purge gas source 86 through the purge valve 84. At the same time, the sublimation regeneration unit 110 starts the reverse temperature increase operation of the refrigerator 16. The sublimation regeneration unit 110 can control the operating frequency of the refrigerator 16 according to the first temperature measurement signal S1 so that the first measured temperature T1 is consistent with the target heating temperature.

[0136] The sublimation regeneration unit 110 compares the first measured temperature T1 with the purge stop temperature Tp (S102) according to the first temperature measurement signal S1. According to the result of the temperature comparison, the sublimation regeneration unit 110 controls the roughing valve 80 and the roughing pump 82. If the first measured temperature T1 is lower than the purge stop temperature Tp (No in S102), the current state is maintained. That is, the purge valve 84 is opened and the roughing valve 80 is closed. The sublimation regeneration unit 110 compares the first measured temperature T1 with the purge stop temperature Tp again after a predetermined time has passed (S102). In addition, the sublimation regeneration unit 110 can also compare the second measured temperature T2 with the purge stop temperature Tp according to the second temperature measurement signal S2.

[0137] The purge stop temperature Tp is set to a temperature value lower than the triple point temperature of water (i.e., 273.15 K). The purge stop temperature Tp can be set to a temperature near and lower than the triple point temperature of water, for example, in the range of about 230 K to 270 K. The purge stop temperature Tp can be set to 250 K.

[0138] If the first measured temperature T1 is higher than the purge stop temperature Tp (Yes in S102), the sublimation regeneration unit 110 closes the purge valve 84 and opens the roughing valve 80 (S103). In this way, the supply of the purge gas to the cryopump 10 is stopped before the cryopanel temperature exceeds the triple point temperature of water. In addition, the roughing valve 80 may be opened slightly later after the purge valve 84 is closed. The sublimation regeneration unit 110 causes the refrigerator 16 to continue the reverse temperature increase operation.

[0139] Next, the sublimation regeneration unit 110 determines whether the roughing valve closing condition is satisfied (S104). The roughing valve closing condition includes the following (a1) and (a2).

[0140] (a1) The measured internal pressure of the cryopump housing 70 is lower than the pressure threshold;

[0141] (a2) The measured temperature of the second cryopanel unit 20 is higher than the temperature threshold value.

[0142] Therefore, the sublimation regeneration unit 110 compares the measured internal pressure of the cryopump housing 70 with the pressure threshold value based on the pressure measurement signal S3. The sublimation regeneration unit 110 compares the second measured temperature T2 with the temperature threshold value based on the second temperature measurement signal S2. The sublimation regeneration unit 110 controls the roughing valve 80 and the purge valve 84 based on these comparison results.

[0143] If the measured internal pressure of the cryopump housing 70 is higher than the pressure threshold (No in S104), the current state is maintained. If the measured temperature of the second cryopanel unit 20 is lower than the temperature threshold (No in S104), the current state is also maintained. That is, the roughing valve 80 is opened and the purge valve 84 is closed. After the prescribed time has passed, it is determined whether the roughing valve closing condition is satisfied (S104).

[0144] The pressure threshold is, for example, selected from the pressure range of 10 Pa to 100 Pa, and may be, for example, 30 Pa. The temperature threshold is, for example, selected from the temperature range of 290 K to 330 K, and may be, for example, 300 K.

[0145] If the roughing valve closing condition is satisfied (Yes in S104), that is, when the measured internal pressure of the cryopump housing 70 is lower than the pressure threshold and the measured temperature of the second cryopanel unit 20 is higher than the temperature threshold, the roughing valve 80 is closed (S105). The purge valve 84 may be opened simultaneously with or slightly delayed from the closing of the roughing valve 80.

[0146] After the roughing valve 80 is closed in step S105 , a subsequent discharge process and cooling process (not shown) are performed, thereby completing the sublimation regeneration sequence.

[0147] The sublimation regeneration sequence is a so-called complete regeneration, and both the first cryopanel unit 18 and the second cryopanel unit 20 are regenerated. Therefore, the cryopump 10 is continuously heated to a regeneration temperature higher than room temperature (e.g., 290K to 330K). Thus, maintaining the cryopump 10 at a relatively high temperature during regeneration helps to shorten the regeneration time.

[0148] In addition, the cryopump regeneration according to the embodiment is suitable for a case where the amount of water condensed in the cryopump 10 is small and the internal pressure of the cryopump 10 does not exceed the triple point pressure of water due to sublimation. In the case where a large amount of water is condensed in the cryopump 10, a large amount of water vapor will be vaporized due to sublimation, and the internal pressure of the cryopump 10 will exceed the triple point pressure of water. In such a case, the controller 100 can maintain the temperature of the cryopump 10 at a temperature lower than the triple point temperature of water, instead of heating the cryopump 10 to a temperature higher than room temperature.

[0149] Fig.10 Yes means Figure 8 Flow chart of the dehydration sequence shown. When the dehydration sequence starts, the dehydration unit 112 opens the purge valve 84 and closes the roughing valve 80 (S201). The purge gas is supplied from the purge gas source 86 to the cryopump housing 70 through the purge valve 84. The supplied purge gas is discharged from the cryopump housing 70 through the exhaust valve 88.

[0150] With the opening of the purge valve 84, the dehydration unit 112 starts the reverse temperature increase operation of the refrigerator 16. The dehydration unit 112 can control the operating frequency of the refrigerator 16 according to the second temperature measurement signal S2 so that the second measured temperature T2 is consistent with the target heating temperature. Alternatively, the dehydration unit 112 can also control the operating frequency of the refrigerator 16 according to the first temperature measurement signal S1 so that the first measured temperature T1 is consistent with the target heating temperature. As described above, the target heating temperature is set to a temperature of 50°C or more, for example.

[0151] Next, the dehydration unit 112 determines whether the dehydration completion condition is satisfied (S202). The dehydration completion condition includes the following (b1) and (b2).

[0152] (b1) the measured temperature of the second cryopanel unit 20 is higher than the temperature threshold;

[0153] (b2) A preset drying time (dehydration waiting time) has elapsed.

[0154] Therefore, the dehydration unit 112 compares the second measured temperature T2 with the temperature threshold value according to the second temperature measurement signal S2. The temperature threshold value may be equal to the target heating temperature. The dehydration unit 112 measures the elapsed time and compares the elapsed time with the pre-set drying time. The elapsed time may be calculated, for example, from the moment when the second measured temperature T2 reaches the temperature threshold value, or may be calculated from the regeneration start instruction S7. The pre-set drying time may be set, for example, to 10 minutes to 60 minutes (e.g., 30 minutes). The dehydration unit 112 controls the roughing valve 80 and the purge valve 84 according to these comparison results.

[0155] If the measured temperature of the second cryopanel unit 20 is lower than the temperature threshold (No in S202), the current state is maintained. If the preset drying time has not passed (No in S202), the current state is also maintained. That is, the roughing valve 80 is opened and the purge valve 84 is kept closed. After the prescribed time has passed, it is determined whether the dehydration completion condition is met (S202).

[0156] If the dehydration completion condition is satisfied (Yes in S202), that is, when the measured temperature of the second cryopanel unit 20 is higher than the temperature threshold and the preset drying time has passed, the purge valve 84 is closed (S203). During the dehydration sequence, the roughing valve 80 remains closed. In this way, the dehydration sequence is terminated.

[0157] Furthermore, as required (eg, when the supply amount of the purge gas is limited), the dehydration unit 112 may close the purge valve 84 before the dehydration completion condition is satisfied.

[0158] Fig.11 Yes means Figure 8 An example of the time-dependent change of temperature and pressure in the regeneration method shown in FIG. In the figure, symbols T1 and T2 respectively represent the measured temperatures of the first cryopanel unit 18 and the second cryopanel unit 20. The temperature values ​​are shown on the left vertical axis. Symbol P represents the measured internal pressure of the cryopump housing 70, and the pressure value is shown in logarithmic form on the right vertical axis.

[0159] The process shown in the figure is the case where the cryopump 10 is started for the first time. The cryopump 10 is at room temperature as a whole, and the internal pressure is at atmospheric pressure. At the start time T0 of the regeneration sequence, the first cryopanel unit 18 and the second cryopanel unit 20 are both about 297K. Therefore, the first measured temperature T1 is higher than the first reference temperature Tr1, and the second measured temperature T2 is higher than the second reference temperature Tr2. Therefore, according to Figure 8 The process shown in the figure first executes the dehydration sequence ( Figure 8 S200), and then perform the sublimation regeneration sequence ( Figure 8 S100).

[0160] If the dehydration sequence begins, the purge valve 84 is opened and the roughing valve 80 is closed ( Fig.10 By supplying the purge gas, the measured internal pressure P of the cryopump housing 70 continues to be maintained at the atmospheric pressure level. By reverse heating of the refrigerator 16, the first cryopanel unit 18 and the second cryopanel unit 20 (including the non-flammable adsorbent 64) are heated to the target heating temperature (e.g., 335K).

[0161] exist Fig.11 At the time Ta shown in FIG. 1 , the second measured temperature T2 reaches the target heating temperature. From the time when the second measured temperature T2 reaches the target heating temperature, the controller 100 calculates the drying time (dehydration waiting time). The drying time is set to 30 minutes. Fig.11 When the drying time is reached at the time Tb shown, it is determined that the dehydration completion condition is met ( Fig.10 S202), end the dehydration sequence ( Fig.10 S203).

[0162] Next, the sublimation regeneration sequence begins. Since the cryopump 10 has been heated, the first measured temperature T1 and the second measured temperature T2 are both higher than the purge stop temperature. Therefore, at time Tb, the purge valve 84 is closed and the roughing valve 80 is opened ( Fig. 9 S103).

[0163] When the internal pressure of the cryopump 10 becomes sufficiently low by vacuum evacuation (rough evacuation) of the cryopump 10, the rough evacuation valve 80 is closed and the cryopump 10 is vacuum evacuated ( Fig.11 More specifically, if the measured internal pressure P of the cryopump housing 70 is lower than the pressure threshold Pa and the measured temperature T2 of the second cryopanel unit 20 is higher than the temperature threshold ( Fig. 9 S104), close the roughing valve 80 ( Fig. 9 S105).

[0164] Then, if Fig.11As shown, a discharge process including so-called rough pumping and purging can be performed. Rough pumping and purging are processes of alternately and repeatedly supplying purge gas to the cryopump 10 and vacuum exhausting. Rough pumping and purging help to discharge water vapor adsorbed on the adsorbent. During rough pumping and purging, the internal pressure and pressure rise rate of the cryopump 10 are monitored, and when these meet the specified values ​​( Fig.11 At time Td in the above example, the cryopump 10 starts cooling. When the first cryopanel unit 18 and the second cryopanel unit 20 are cooled to the target cooling temperature, the process is completed.

[0165] As described above, according to the embodiment, the non-combustible adsorbent 64 can be dehydrated before starting the vacuum exhaust operation of the cryopump 10. Even if the non-combustible adsorbent 64 has absorbed moisture in the previous operation (manufacturing, transportation, storage, installation, etc.), the non-combustible adsorbent 64 can be prevented from being damaged by vacuum extraction, and the cryopump 10 can be operated.

[0166] Furthermore, even if the ice stored in the cryopump 10 melts due to a power outage or other abnormal conditions during the vacuum pumping operation of the cryopump 10, thereby exposing the non-flammable adsorbent 64 to a high humidity environment, the cryopump 10 can perform a dehydration sequence after the abnormal condition is recovered, thereby drying the non-flammable adsorbent 64. Therefore, the non-flammable adsorbent 64 can be prevented from being damaged by vacuum pumping, and the cryopump 10 can be operated.

[0167] The controller 100 controls the heating device in the dehydration sequence to heat the non-combustible adsorbent 64 and the cryopanel 60 to 50° C. or higher. By utilizing heating, the non-combustible adsorbent 64 can be dehydrated in a short time.

[0168] Furthermore, the controller 100 opens the purge valve 84 during the dehydration sequence to supply the purge gas to the cryopump housing 70. By using the purge gas, the non-combustible adsorbent 64 can be dehydrated in a short time.

[0169] Furthermore, the controller 100 maintains the rough valve 80 in a closed state during the dehydration sequence. This can prevent the internal pressure of the cryopump housing 70 from being excessively reduced during the dehydration sequence.

[0170] According to the sublimation regeneration sequence, ice is directly vaporized into water vapor by sublimation without passing through liquid water. Therefore, the hydrophilic adsorbent material does not come into contact with liquid water during regeneration. Since the amount of water adsorbed on the adsorbent material is reduced, the time required for dehydration of the adsorbent material can be shortened. Therefore, the regeneration time can be shortened. And, as mentioned above, silica gel has the property of becoming brittle and then naturally breaking after being immersed in liquid water. However, according to the present embodiment, the hydrophilic adsorbent material does not come into contact with liquid water during regeneration. Therefore, in the case where the hydrophilic adsorbent material contains silica gel, the life of the hydrophilic adsorbent material can be extended.

[0171] The present invention has been described above based on the embodiments. It should be understood by those skilled in the art that the present invention is not limited to the above-mentioned embodiments, and various design changes can be made and various modifications exist, and such modifications also belong to the scope of the present invention. The various features described in one embodiment may also be applicable to other embodiments. The new embodiment generated by the combination has the effects of the combined embodiments.

[0172] In one embodiment, an additional dehydration sequence may be executed after the basic dehydration sequence described above. The controller 100 (e.g., the dehydration unit 112) may be configured to execute the additional dehydration sequence based on the first temperature measurement signal S1, the second temperature measurement signal S2, and the pressure measurement signal S3. The additional dehydration sequence may be configured to reduce the water remaining in the non-flammable adsorbent material 64 by vacuum exhaust (rough pumping) of the cryopump housing 70 based on the rough pump valve 80. Alternatively, the additional dehydration sequence may be configured to reduce the water remaining in the non-flammable adsorbent material 64 by alternating and repeating the vacuum exhaust of the cryopump housing 70 based on the rough pump valve 80 and the rough pumping and purging of the purge gas supplied to the cryopump housing 70 based on the purge valve 84. Rough pumping and purging are exemplified in Fig.11 After the roughing and purging, cooling is performed, and the additional dehydration sequence is terminated. In this way, the vacuum exhaust operation of the cryopump 10 is started. In addition, the additional dehydration sequence may also be a part of the above-mentioned sublimation regeneration sequence.

[0173] Fig.12 A diagram schematically shows a cryopump system according to an embodiment. The cryopump system includes a plurality of cryopumps, specifically, at least one first cryopump 10a and at least one second cryopump 10b. Fig.12 In the example shown, the cryopump system is composed of four cryopumps, namely, two first cryopumps 10a and two second cryopumps 10b, but the number of the first cryopumps 10a and the second cryopumps 10b is not particularly limited. These multiple cryopumps can be respectively arranged in different vacuum chambers or in the same vacuum chamber.

[0174] The first cryopump 10a is a cryopump having an adsorbent material (containing silica gel as a main component), for example Figure 1 The second cryopump 10b is a cryopump having an adsorbent material (such as activated carbon) that does not contain silica gel. The structure of the second cryopump 10b is similar to that of the first cryopump except that the adsorbent material is different. Figure 1 The structures of the cryopumps 10 shown are the same. Therefore, the first cryopump 10 a includes a cryopump housing 70 and a roughing valve 80 . Similarly, the second cryopump 10 b includes a cryopump housing 70 and a roughing valve 80 .

[0175] The cryopump system includes a rough exhaust line 130. The rough exhaust line 130 includes a rough pump 82 shared by the first cryopump 10a and the second cryopump 10b, and a rough pipe 132 that joins the rough valves 80 of the cryopumps 10a and 10b to the shared rough pump 82. The rough pump 82 is shared by a plurality of first cryopumps 10a and a plurality of second cryopumps 10b.

[0176] The controller 100 is configured to receive the regeneration start command S7 of each cryopump 10a, 10b and start regeneration of the cryopump. The regeneration start command S7 is received from, for example, the input unit 104 (see Figure 7 ) is input to the controller 100.

[0177] However, the cryopumps 10a and 10b are connected to each other through the rough exhaust line 130, so when several cryopumps are regenerated at the same time, the gas may flow back from a certain cryopump (referred to as cryopump A) to other cryopumps (referred to as cryopump B). For example, assuming that the cryopump B transitions from purging to roughing while the roughing pump 82 is roughing the cryopump A, at the transition time, the internal pressure of the cryopump B becomes higher than the internal pressure of the cryopump A due to the purge gas. Therefore, based on the pressure difference between the two cryopumps, the gas may flow back from the cryopump B to the cryopump A through the roughing pipe 132.

[0178] In particular, when the cryopump A is the first cryopump 10a, such gas backflow is undesirable. The reason is that the first cryopump 10a will increase pressure due to the backflow, and the internal pressure may exceed the triple point pressure of water. In this case, ice may liquefy into water in the first cryopump 10a. The risk of silica gel contained in the adsorbent material coming into contact with liquid water increases.

[0179] Furthermore, due to the backflow generated from the rough pump pipe 132 to the cryopumps 10 a and 10 b , there is a possibility that particles may enter the cryopumps.

[0180] Therefore, the controller 100 can make the multiple first cryopumps 10a perform the basic dehydration sequence at the same time, and make the multiple first cryopumps 10a perform the additional dehydration sequence in sequence. The roughing valve 80 is closed in the basic dehydration sequence, so even if the multiple first cryopumps 10a perform the basic dehydration sequence at the same time, the above-mentioned problem will not occur. The roughing valve 80 is opened in the additional dehydration sequence, but the multiple first cryopumps 10a perform the additional dehydration sequence in sequence, so the multiple roughing valves 80 will not be opened at the same time. Therefore, it is possible to prevent the gas from flowing back between the multiple first cryopumps 10a.

[0181] The roughing valve 80 is also opened in the above-mentioned sublimation regeneration sequence. Therefore, similarly, the controller 100 can make the plurality of first cryopumps 10a simultaneously perform the basic dehydration sequence and make the plurality of first cryopumps 10a perform the sublimation regeneration sequence in sequence. In this way, it is possible to prevent the gas from flowing back between the plurality of first cryopumps 10a.

[0182] Furthermore, if the controller 100 receives a regeneration start instruction S7 of at least one other cryopump (i.e., the second cryopump 10b) during the dehydration of the first cryopump 10a (basic dehydration sequence and / or additional dehydration sequence), the regeneration of the at least one other cryopump can be delayed until the dehydration of the first cryopump 10a is completed. Therefore, it is possible to prevent the gas from flowing back from the second cryopump 10b to the first cryopump 10a.

[0183] The present invention has been described above based on the implementation mode and specific terms; however, the implementation mode only represents one aspect of the principle and application of the present invention, and there may be various modifications and changes in configuration without departing from the scope of the idea of ​​the present invention described in the technical solution.

[0184] Industrial Applicability

[0185] The present invention can be used in the fields of a cryopump, a cryopump system, and a cryopump regeneration method.

[0186] Explanation of symbols

[0187] 110-cryogenic pump, 60-cryogenic plate, 64-non-flammable adsorbent material, 70-cryogenic pump housing, 80-roughing valve, 82-roughing pump, 84-purge valve, 86-purge gas source, 100-controller.

Claims

1. A cryogenic pump, characterized in that: have: Cryogenic pump housing; A cryopanel, disposed in the cryopump housing and having a non-flammable adsorbent material; A heating device for heating the non-combustible adsorption material and the cryopanel; a purge valve mounted on the cryopump housing and connecting the cryopump housing to a purge gas source; a roughing valve mounted on the cryopump housing and connecting the cryopump housing to the roughing pump; a sensor that generates a measurement signal representing a temperature of the non-flammable adsorbent material or an internal pressure of the cryopump housing; and A controller receives a regeneration start instruction and controls at least one of the heating device, the purge valve and the roughing valve according to the measurement signal to select either one of (i) a sublimation regeneration sequence or (ii) a dehydration sequence and execute the selected sequence, wherein the sublimation regeneration sequence is configured to sublime water from the non-combustible adsorbent material by exposing the non-combustible adsorbent material to a vacuum environment, and the dehydration sequence is configured to dehydrate the non-combustible adsorbent material by exposing the non-combustible adsorbent material to a dry environment with a pressure higher than the vacuum environment at room temperature or a temperature higher than the room temperature.

2. The cryopump according to claim 1, characterized in that The sensor includes a temperature sensor that generates a temperature measurement signal representing the temperature of the non-combustible adsorbent material. The controller controls at least one of the heating device, the purge valve, and the roughing valve according to the temperature measurement signal, thereby performing the dehydration sequence under the condition that the non-combustible adsorbent material is regarded as being at room temperature.

3. The cryopump according to claim 2, characterized in that The controller controls at least one of the heating device, the purge valve, and the roughing valve according to the temperature measurement signal so as to perform the sublimation regeneration sequence when the non-combustible adsorbent is considered to be at a temperature lower than room temperature.

4. The cryopump according to any one of claims 1 to 3, characterized in that The controller may control at least one of the heating device, the purge valve and the roughing valve according to the state of the cryopump just before receiving the regeneration start instruction instead of the measurement signal, thereby executing either the sublimation regeneration sequence or the dehydration sequence.

5. The cryopump according to any one of claims 1 to 3, characterized in that The controller controls the heating device in the dehydration sequence so as to heat the non-combustible adsorbent and the cryopanel to 50° C. or higher.

6. The cryopump according to any one of claims 1 to 3, characterized in that The controller opens the purge valve in the dehydration sequence to allow a purge gas to be supplied to the cryopump housing.

7. The cryopump according to any one of claims 1 to 3, characterized in that The controller maintains the roughing valve in a closed state during the dehydration sequence.

8. The cryopump according to any one of claims 1 to 3, characterized in that The pressure of the vacuum environment is less than 100 Pa, and the pressure of the dry environment is at least 1000 Pa.

9. The cryopump according to any one of claims 1 to 3, characterized in that The pressure of the dry environment is at least 1 atmosphere.

10. The cryopump according to any one of claims 1 to 3, wherein: The non-combustible adsorbent contains silica gel as a main component.

11. The cryopump according to any one of claims 1 to 3, characterized in that The cryopump does not have activated carbon.

12. The cryopump according to any one of claims 1 to 3, characterized in that The controller controls at least one of the heating device, the purge valve, and the roughing valve to perform an additional dehydration sequence after the dehydration sequence. The additional dehydration sequence is constructed to reduce the water remaining in the non-flammable adsorbent by vacuum exhausting the cryopump housing based on the rough exhaust valve, or by alternating and repeating the vacuum exhaust and rough exhausting and purging of the purge gas supplied to the cryopump housing based on the purge valve.

13. The cryopump according to any one of claims 1 to 3, characterized in that The controller controls at least one of the heating device, the purge valve, and the roughing valve so that the sublimation regeneration sequence is performed after the dehydration sequence.

14. A cryopump system, characterized in that: have: The cryopump according to claim 12; and at least one other cryopump, The roughing pump is shared by the cryopump and the at least one other cryopump, The controller causes the cryopump and the at least one other cryopump to simultaneously execute the dehydration sequence, and causes the cryopump and the at least one other cryopump to sequentially execute the additional dehydration sequence.

15. A cryopump system, characterized in that: have: The cryopump according to claim 13; and at least one other cryopump, The roughing pump is shared by the cryopump and the at least one other cryopump, The controller causes the cryopump and the at least one other cryopump to simultaneously perform the dehydration sequence, and causes the cryopump and the at least one other cryopump to sequentially perform the sublimation regeneration sequence.

16. A cryopump system, characterized in that: A plurality of cryopumps are provided, wherein the plurality of cryopumps include a plurality of first cryopumps, wherein the first cryopump includes: Cryogenic pump housing; A cryopanel, disposed in the cryopump housing and having a non-flammable adsorbent material; A heating device for heating the non-combustible adsorption material and the cryopanel; a purge valve mounted on the cryopump housing and connecting the cryopump housing to a purge gas source; and a roughing valve mounted on the cryopump housing and connecting the cryopump housing to the roughing pump; The cryopump system further includes a controller for controlling at least one of the heating device, the purge valve, and the roughing valve according to a dehydration sequence, and controlling at least one of the heating device, the purge valve, and the roughing valve to perform an additional dehydration sequence or a sublimation regeneration sequence after the dehydration sequence. The roughing pump is shared by a plurality of first cryopumps. The sublimation regeneration sequence is configured to sublime water from the non-flammable adsorbent by exposing the non-flammable adsorbent to a vacuum environment. The dehydration sequence is configured to dehydrate the non-combustible adsorbent by exposing the non-combustible adsorbent to a dry environment having a pressure higher than the vacuum environment at room temperature or a higher temperature, The additional dehydration sequence is configured to reduce the water remaining in the non-flammable adsorbent by vacuum exhausting the cryopump housing by the rough exhaust valve, or by alternately repeating the vacuum exhaust and the supply of the purge gas to the cryopump housing by the purge valve, rough exhaust and purge. The controller causes the plurality of first cryopumps to simultaneously execute the dehydration sequence, and causes the plurality of first cryopumps to sequentially execute the additional dehydration sequence or the sublimation regeneration sequence.

17. A controller for a cryopump, the cryopump comprising a non-flammable adsorbent, the controller for the cryopump being characterized in that the controller is configured to execute the following steps: acquiring the temperature of the non-flammable adsorbent material, the pressure in the cryopump, or the state of the cryopump; selecting, based on the acquired temperature of the non-combustible adsorbent material, the pressure in the cryopump, or the state of the cryopump, either one of (i) a sublimation regeneration sequence in which water is sublimated from the non-combustible adsorbent material by exposing the non-combustible adsorbent material to a vacuum environment or (ii) a dehydration sequence in which water is dehydrated by exposing the non-combustible adsorbent material to a dry environment at a higher pressure than the vacuum environment at room temperature or a higher temperature; and The sequence selected from the sublimation regeneration sequence and the dehydration sequence is executed.

18. A method for starting operation of a cryopump, the cryopump having a non-flammable adsorbent, the method comprising the following steps: acquiring the temperature of the non-flammable adsorbent material, the pressure in the cryopump, or the state of the cryopump; selecting, based on the acquired temperature of the non-combustible adsorbent material, the pressure in the cryopump, or the state of the cryopump, either one of (i) a sublimation regeneration sequence in which water is sublimated from the non-combustible adsorbent material by exposing the non-combustible adsorbent material to a vacuum environment or (ii) a dehydration sequence in which water is dehydrated by exposing the non-combustible adsorbent material to a dry environment at a higher pressure than the vacuum environment at room temperature or a higher temperature; and The sequence selected from the sublimation regeneration sequence and the dehydration sequence is executed.

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