KR20120127282A - Cryo-pump and fabrication method thereof - Google Patents

Abstract

PURPOSE: A cryo-pump and a manufacturing method thereof are provided to easily discharge noncondensable gas by exposing a vertical panel toward the opening of the cryo-pump. CONSTITUTION: A cryo-pump comprises a refrigerator(12), a radiation shield(16), and a cryo panel assembly(14). The cryo panel assembly comprises a top panel(60) and a middle panel(62).. An open part placed between a cryo panel(50) facing the front side of the middle panel and the front side of the middle panel is formed. The depth of the open part is larger than the gap between the cryo panel and the front side of the middle panel. The middle panel comprises an absorption area(76) for noncondensable gas.

Description

Cryopump and its manufacturing method {Cryo-pump and fabrication method

This application claims priority based on Japanese Patent Application No. 2011-107669 for which it applied on May 12, 2011. The entire contents of that application are incorporated by reference in this specification.

The present invention relates to a cryopump and a manufacturing method thereof.

The cryopump is a vacuum pump which traps gas molecules by condensation or adsorption on the cryopanel cooled to cryogenic temperatures and exhausts them. Cryopumps are generally used to realize a clean vacuum environment required for semiconductor circuit manufacturing processes and the like. One of the applications of cryopumps, such as in ion implantation processes, is when non-condensable gases such as hydrogen occupy most of the gases to be exhausted. The non-condensable gas can be exhausted only by adsorbing to the adsorption region cooled to cryogenic temperature.

Japanese Patent Laid-Open No. 01-092591 Japanese Patent Application Laid-Open No. 60-013992 Japanese Patent Publication No. 2008-514849 Japanese Patent Publication No. 2009-162074

One exemplary object of certain aspects of the present invention is to provide a cryopump for high speed exhaust of a non-condensable gas such as hydrogen, and a method for producing such cryopump.

The cryopump according to any aspect of the present invention has a first cooling stage for providing a first cooling temperature, and a second cooling temperature for providing a second cooling temperature lower than the first cooling temperature and used for adsorption of non-condensable gas. A freezing stage including a cooling stage, a shield front end forming a opening for receiving gas, a radiation shield thermally connected to the first cooling stage, and surrounding the second cooling stage; and a second cooling stage. A cryopanel assembly thermally connected to a cryopanel assembly is provided between the outer periphery and the radiation shield to form an open space to the opening, and a cryopanel assembly capable of viewing at least a part of the shield front end. The cryopanel assembly includes a top panel in contact with the opening, an intermediate panel including a front panel facing the opening and disposed opposite the opening with respect to the top panel, A continuous opening is formed between the adjacent cryopanel facing the front of the panel and the front of the panel, the opening having a depth greater than the distance between the adjacent cryopanel and the front of the panel. And the intermediate panel has an adsorption region for non-condensable gas on the front surface of the panel, the adsorption region being a boundary defined by the line of sight from the front end of the shield to the end of the adjacent cryopanel and the front surface of the panel. It is formed inside.

The cryopump according to any aspect of the present invention has a radiation shield, a front side inwardly arranged within the radiation shield, each having a front face facing the opening of the radiation shield and a back side opposite the opening. And a cryopanel assembly comprising an arrangement of a plurality of cryopanels and forming an open space in the opening between an outer circumference of the plurality of cryopanels and the radiation shield. The cryopanel assembly has at least 70% of the total area of the front and rear surfaces of the plurality of cryopanels covered with a hydrogen adsorbent, so that the cryopump has a hydrogen trapping probability of at least 30%, and The adsorbent is contained between each rear surface of the plurality of cryopanels and the front surface of the cryopanel adjacent to the inside of the cryopanel, and the adsorbent is visible from the opening with respect to the total area of the adsorbents of the plurality of cryopanels. The adsorbent visibility rate which is a ratio of area is less than 7%.

The cryopump according to one aspect of the present invention comprises an arrangement of a plurality of cryosorption panels surrounded by a cryopump internal open space opened in the cryopump opening, and the cryopump internal opening. And a radiation shield surrounding the space. At least one of the plurality of cryor sorption panels includes a panel end that projects into the cryopump internal open space and faces the radiation shield, the panel end having an area in which the adsorbent is missing.

Another aspect of the present invention is a method for producing a cryopump. This method includes masking the substrate of the cryopanel and adhering the adsorbent to the surface of the substrate which is not masked.

According to the present invention, there is provided a cryopump for high-speed exhaust of non-condensable gas such as hydrogen, and a method for producing such cryopump.

1 is a diagram schematically illustrating an ion implantation apparatus and a cryopump according to an embodiment of the present invention.
2 is a cross-sectional view schematically showing a cryopump according to an embodiment of the present invention.
3 is a top view schematically showing a cryopump according to a preferred embodiment.
4 is a cross-sectional view schematically showing a cryopump according to a preferred embodiment.
FIG. 5 is a diagram for explaining an adsorption region formed in the cryopanel with respect to the cryopump shown in FIG. 4.
FIG. 6 is a top view of the front panel of the cryopanel with respect to the cryopump shown in FIGS. 4 and 5.
FIG. 7 is a diagram illustrating a rear surface of the cryopanel illustrated in FIG. 6.
8 is a table showing an example of an adsorbent dropping rate or a covering rate of a cryopanel assembly according to an embodiment of the present invention.
9 is a table showing an example of an adsorbent dropping rate or a covering rate of a cryopanel assembly according to an embodiment of the present invention.
FIG. 10 is a view showing a hydrogen exhaust rate change of the cryopump through regeneration according to one embodiment of the present invention.
11 is a flowchart for explaining a method for producing a cryopump according to an embodiment of the present invention.
12 is a flowchart for explaining a method for producing a cryopump according to an embodiment of the present invention.

The cryopump according to any aspect of the present invention includes an exposed cryo sorption panel array. The panel arrangement has a region in which adsorbents such as activated carbon have been missing from the cryopump opening at first sight or other sites. Most panel surfaces and adsorbents thereon are covered by adjacent panels and are configured to be invisible directly from the cryopump opening, so that the adsorbent viewing rate from the cryopump opening is zero or slightly. The adsorbent is exposed to the open space surrounding the panel array. The adsorbent missing zone is formed on the same plane as the adsorbent present zone, and the boundary of the adsorbent missing zone is defined by the adsorbent. That is, the missing zone and the existing zone of the adsorbent distinguish common panel surfaces.

This hybrid construction of exposure and non-exposure contributes to both high speed exhaust of non-condensable gas and protection of adsorbent from egg regeneration gas. This leads to maintaining stable exhaust performance through repetition of a plurality of regeneration processes. Further, the reduction in the visibility rate due to the adsorbent missing from the sorption panel contributes to the improvement of the exhaust efficiency of the non-condensable gas and further to the provision of the cryopump excellent in energy saving.

In some typical applications of cryopumps, the gas to be exhausted includes a condensable gas and a small amount of non-condensable gas. In order to avoid impairing the adsorption performance of non-condensable gases by the deposition of ice layers of condensable gases, the cryopumps for this typical application are either cryosorbed panels or adsorption by cryo condensation panels or condensation panels. It hides the panel. A typical cryosorption panel is formed by covering the entirety of one side with activated carbon.

For example, one cryopanel structure has a double structure having a condensation panel for trapping condensable gas on the outside and a sorption panel for trapping non-condensable gas on the inside. Another cryopanel structure has a cryo condensation surface on its surface facing the cryopump opening and a cryosorption surface on its back. If the panel has a bent portion at its end, for example, the entire area of one side of the panel, except for the surface of the bent portion divided by the bend lines, is covered with activated carbon, or the entire area including the surface of the bent portion is covered with activated carbon.

In general, both the condensation panel and the sorption panel are cooled to a common cooling temperature such as cryogenic temperatures of 10K to 20K. The condensation panel and the sorption panel are surrounded by a radiation shield or a radiation shield to protect them from radiant heat. The spinning shield is cooled to a cryogenic temperature, such as 80 K to 100 K, which is higher than the condensation panel and the sorption panel. The radiation shield may be considered a cryopanel that provides a relatively hot cryogenic surface.

Depending on the application of the cryopump, the condensation of the condensable gas on the cryogenic surface may not be a problem. For example, the cryopump for ion implantation apparatus is mentioned. In this application, the amount of gas condensed in the low-temperature cryopanel is small, and the main purpose of the cryopump is to exhaust non-condensable gas (for example, hydrogen). Accordingly, it is desirable to expose the non-condensable gas by exposing the sorption panel toward the cryopump opening. As a result, a high exhaust speed can be realized.

The improvement of the exhaust velocity by exposure contributes to the reduction of the sorption panel area for realizing any required exhaust velocity. This is because the exposure of the gas to the adsorbent becomes good due to exposure, and the exhaust velocity per panel unit area is increased. As a result, the required panel area is reduced and the weight of the cryopanel structure is also reduced.

Reducing the panel weight shortens the time required for the regeneration treatment of the cryopump. Since the cryopump is a so-called storage vacuum pump, a regeneration process for discharging the gas accumulated therein to the outside at an appropriate frequency is performed. In the regeneration, the cryopanel is heated to a temperature higher than the operating temperature of the cryopanel (for example, room temperature), the gas condensed or adsorbed on the panel surface is discharged again and discharged to the outside, and cooled again to the cryopanel operating temperature. It is processing. One big factor in determining the regeneration time is the time required for recooling. The recooling time is correlated with the panel structure weight. By reducing the weight of the panel structure, the recooling time is shortened, and as a result, the regeneration time is also shortened.

The gas accumulated in the cryopump is usually discharged substantially completely by the regeneration treatment, and upon completion of the regeneration, the cryopump is restored to the exhaust performance on the specification. However, some of the accumulated gas remains relatively high in the adsorbent even after regeneration.

For example, in the cryopump provided for the vacuum exhaust of the ion implanter, it was observed that a sticky substance adhered to activated carbon as an adsorbent. It was difficult to remove this adhesive substance completely even after regenerating. It is thought that this adhesive substance originates in the organic type outgas discharged | emitted from the photoresist coat | covered by the process target substrate. Or it may be due to the toxic gas used as the dopant gas, that is, the raw material gas in the ion implantation treatment. It is also conceivable that this may be due to other by-product gases in the ion implantation treatment. It is also possible that an adhesive substance is produced due to a complex relationship between these gases.

In the ion implantation process, most of the gas exhausted by the cryopump may be hydrogen gas. Hydrogen gas is discharged to the outside substantially completely by regeneration. If the regeneration gas is small, the influence of the regeneration gas on the exhaust performance of the cryopump in one cryopumping process is slight. However, during the repetition of the cryopumping process and the regeneration process, the regenerated gas gradually accumulates in the adsorbent, which may lower the exhaust performance. When the exhaust performance is less than the allowable range, maintenance work including, for example, the replacement of the cryopanel with the adsorbent or with the adsorbent, or the removal of chemically regenerated gas into the adsorbent is necessary.

Accordingly, the cryopump according to any aspect of the present invention includes an exposed cryo sorption panel array, in which a sorbent such as activated carbon is eliminated. The exposed cryo sorption panel array has a cryopump internal open space that is open around the cryopump opening. This internal open space is surrounded by the radiation shield. The open local space is defined by the adjacent sorption panels of the cryo sorption panel array, and the local space is opened to the cryopump external space through the cryopump internal open space. The openness of the cryo sorption panel promotes the arrival of gas to the panel surface, thereby supporting the realization of high velocity exhaust of non-condensable gas such as hydrogen by the cryopump.

In one embodiment, the missing portion of the adsorbent is set in the zone of the cryo sorption panel visually recognized through the cryopump opening from the outside of the cryopump. The adsorbent missing portion may be provided at the end of the sorption panel which protrudes into the cryopump internal open space and faces the radiation shield. The missing portion can be used as a cryo condensation panel.

In this way, by avoiding direct exposure of the adsorbent to the cryopump opening, or by making the adsorbent visibility rate very low from the cryopump opening, the action of the adsorbent by the regenerating gas contained in the gas entering the cryopump Is prevented or alleviated. The refractory gas is integrated in the condensation panel, and the accumulation of the sticky substance in the adsorbent is reduced. In this way, the high speed exhaust of the non-condensable gas and the protection of the adsorbent from the regeneration gas can be compatible.

A cryopump according to one embodiment of the technical idea is a cryopump suitable for use in a vacuum exhaust machine of an ion implantation apparatus. Another example is a cryopump suitable for use in a vacuum exhaust machine of a substrate processing apparatus. The substrate processing apparatus, for example, processes a substrate coated with a resist with a process gas.

Here, the non-regeneration gas is, for example, a gas in which discharge to the outside of the pump is not completed when discharge of the predetermined gas (for example, hydrogen) to the outside of the cryopump is substantially completed in the predetermined regeneration process. In addition, the gas whose residual in an adsorbent exceeds a reference | standard can be said to be a regeneration gas even after the regeneration process adjusted so that predetermined gas may be discharged to the outside of a cryopump substantially completely. For example, there exists a possibility that the residual ratio to the adsorbent in a regeneration process may be high also about the organic outgas from the resist apply | coated to the wafer surface or other coating. In addition, the toxic dopant gas used in the ion implantation treatment may also be a regeneration gas.

The resist is an organic resist made of, for example, an organic material. The process gas may be a reactive process gas which chemically reacts directly with a resist on the processing target (for example, a substrate) or its surface. Alternatively, the process gas may be a gas for supporting the introduction of the reactive gas into the treatment target. When the substrate processing apparatus is a sputter apparatus, the process gas is an inert gas such as argon. When the substrate processing apparatus is an ion implantation apparatus, the process gas is, for example, hydrogen gas or dopant gas. By the interaction of the process gas and the resist during the process, the organic gas can be released from the resist. In addition, the outgas may be released from the resist by the vacuum environment even when not in the process. The organic gas may include, for example, an aromatic, straight chain hydrocarbon, alcohol, ketone, ether or the like.

The refractory gas is not limited to the organic gas from the resist described above and the dopant gas used in the ion implantation treatment. For example, depending on the process, the process gas itself may be a non-regeneration gas. In addition, the release gas from the coating other than the resist on the substrate may be a regenerating gas.

A cryopump according to one embodiment includes a first cooling stage for providing a first cooling temperature and a second cooling temperature for providing a second cooling temperature lower than the first cooling temperature and used for adsorption of non-condensable gas. A refrigerator comprising a stage, a shield front end forming a opening for receiving gas, and thermally connected to the first cooling stage, the radiation shield surrounding the second cooling stage, and thermally connected to the second cooling stage. As a cryopanel assembly, a cryopanel assembly may be provided between the outer circumferential portion and the radiation shield to form an open space in the opening, and visually recognize at least a portion from the front end of the shield.

The cryopanel assembly may include a top panel in contact with the shield opening, and an intermediate panel including a front surface of the panel facing the shield opening and disposed opposite the shield opening with respect to the top panel. An open portion continuous to the open space may be formed between the adjacent cryopanel facing the front panel of the middle panel and the front panel. The opening may have a depth greater than the distance between the adjacent cryopanel and the front of the panel.

The intermediate panel may have an adsorption zone for non-condensable gases on the front of the panel. The adsorption region may be formed inside the boundary determined by the intersection of the line of sight from the front end of the shield to the end of the adjacent cryopanel and the front surface of the panel. The adsorption area may occupy an area inside the boundary on the front surface of the panel.

The intermediate panel may have a condensation zone for condensable gas on its surface. The condensation area may include an area outside the boundary on the front of the panel.

The outer periphery of the intermediate panel may extend parallel to the top panel and to a position closer to the radiation shield than the outer periphery of the top panel. The intermediate panel may include a plurality of plates arranged in parallel with each other including a front face facing the shield opening and a back face facing the opening.

The cryopanel assembly may include a lower panel disposed on the side opposite to the shield opening with respect to the intermediate panel. The outer periphery of the lower panel may extend parallel to the middle panel and to a position closer to the radiation shield than the outer periphery of the middle panel.

The cryopump may be provided with a louver thermally connected to the radiation shield and arranged at the shield opening. The louver has a size between the top panel and the middle panel, and an open area may be formed between the outer periphery of the louver and the radiation shield.

At least 70% of the surface area of the intermediate panel is covered with an adsorbent, the adsorbent being capable of hydrogen adsorption, and the cryopump may have a hydrogen capture probability of at least 30%. The adsorbent may be contained in the open portion, and the adsorbent viewing rate, which is the ratio of the adsorbent area visible from the shield opening to the total area of the adsorbent, may be less than 7%.

A cryopump according to one embodiment includes a radiation shield, a plurality of cryos having a front side facing inward from the inside of the radiation shield, the front side facing the opening of the radiation shield and the back side facing the opening. A cryopanel assembly may be provided which includes an arrangement of panels and forms an open space in the opening between the outer peripheral portions of the plurality of cryopanels and the radiation shield. In the cryopanel assembly, at least 70% of the total area of the front and rear surfaces of the plurality of cryopanels is covered with an adsorbent capable of hydrogen adsorption, and the cryopump may have a hydrogen trapping probability of at least 30%. The adsorbent is contained between each rear surface of the plurality of cryopanels and the front surface of the cryopanel adjacent to the inside of the cryopanel, and the adsorbent area is visible from the shield opening for the total area of the adsorbents of the cryopanel. The adsorbent visibility rate which is a ratio may be less than 7%.

The arrangement of the plurality of cryopanels is a shielded portion of the cryopanel such that at least a part of the inner cryopanel is shielded from the opening by the front cryopanel, and the adsorbent is invisible from the shield opening. It may be formed in.

The total area of the adsorbent may be 90% or less of the total area of the front and rear surfaces of the plurality of cryopanels.

At least 90% of the adsorbent may be exposed to the radiation shield or the shield opening.

The cryopump according to one embodiment includes an arrangement of a plurality of cryo sorption panels surrounded by a cryopump internal open space opened through the cryopump opening, and a radiation shield surrounding the cryopump internal open space. You may provide it. At least one of the plurality of cryor sorption panels may include a panel end that protrudes into the cryopump internal open space and faces the radiation shield, and the panel end may have a region in which an adsorbent is missing.

The adsorbent missing zone may be formed on the same plane as the adsorbent presence zone. The surface of the cryopanel base material may be exposed in the adsorbent elimination zone for cryo condensation. The adsorbent missing zone may be at the peripheral edge exposed portion visually recognized through the cryopump opening.

The manufacturing method of the cryopump according to one embodiment may include masking the substrate of the cryopanel and adhering an adsorbent to the surface of the substrate which is not masked. Masking may include masking the exposed portion of the substrate not shielded by another cryopanel. This method is based on the boundary determined by the intersection of the line of sight and the cryopanel from the front end of the radiation shield to the end of the cryopanel adjacent to the cryopanel for each cryopanel of the array of cryopanels. It may include determining the outside of the mask as a masking area.

A cryopump according to one embodiment includes a first cooling stage for providing a first cooling temperature and a second cooling temperature for providing a second cooling temperature lower than the first cooling temperature and used for adsorption of non-condensable gas. A refrigerator comprising a stage, a shield front end forming a opening for receiving gas, and thermally connected to the first cooling stage, the radiation shield surrounding the second cooling stage, and thermally connected to the second cooling stage. The cryopanel assembly may be provided with a cryopanel assembly which forms an open space in the shield opening between its outer edge and the radiation shield and can visually recognize at least a portion from the front end of the shield.

The cryopanel assembly may include a top panel facing the shield opening, and an intermediate panel including a front surface of the panel facing the shield opening and disposed opposite the shield opening with respect to the top panel. The outer periphery of the adjacent cryopanel facing the front of the panel of the middle panel and the portion of the front of the panel opposite the outer periphery extend in parallel toward the radiation shield in the open space, the front of the panel adsorbing for non-condensable gas. It may be divided into a zone and a condensation zone for the condensable gas. The outer periphery of the front panel may be divided into an adsorption zone for non-condensable gases and a condensation zone for condensable gases.

The adjacent cryopanel is a top panel, and the outer peripheral portion of the intermediate panel may extend to a position closer to the radiation shield than the outer peripheral portion of the top panel. Each of the top panel and the middle panel includes a plurality of plates arranged in parallel with each other, each including a front face facing the shield opening and a back face facing the opening, the plate of the middle panel being a plate of the top panel. It may be larger.

The cryopanel assembly may further include a lower panel disposed on the side opposite to the shield opening with respect to the intermediate panel. The outer peripheral portion of the lower panel may extend parallel to the intermediate panel and to a position closer to the radiation shield than the outer peripheral portion of the intermediate panel. The lower panel includes a plurality of plates arranged in parallel with each other including a front face facing the shield opening and a rear face facing the opening, and the plate may be larger than the plate of the middle panel.

An open portion continuous to the open space is formed between the portion of the front panel of the middle panel and the outer periphery of the adjacent cryopanel, the open portion having a depth between the adjacent cryopanel and the front surface of the panel. It may be larger.

The cryopump may be thermally connected to the radiation shield and may include a louver disposed at the shield opening. The louver has a middle size between the top panel and the middle panel, and an open area may be formed between the outer periphery of the louver and the radiation shield.

The cryopump has a hydrogen trapping probability of at least 30%, and the middle panel includes a cryopanel substrate for supporting the surface with a hydrogen adsorptive adsorbent, the adsorbent at as high as 30% of the total surface area of the cryopanel substrate. By dropping off, the hydrogen exhaust efficiency, which is the ratio between the hydrogen exhaust rate of the cryopump and the adsorbent area, may be increased as compared with the case where the entire surface of the cryopanel base material is covered with the adsorbent.

A cryopump according to one embodiment includes a radiation shield and a plurality of cryopanels arranged in front of the inside of the radiation shield and between the outer periphery of the plurality of cryopanels and the radiation shield. The cryopump may be provided with a cryopanel assembly that forms an open space of and has a hydrogen trapping probability of at least 30%. Each of the plurality of cryopanels includes a cryopanel substrate for supporting the adsorbent capable of hydrogen adsorption on the surface, and the cryopanel substrate is eliminated by removing the adsorbent at at least 30% of the total surface area of the cryopanel substrate. The hydrogen exhaust efficiency, which is the ratio of the hydrogen evacuation rate of the cryopump to the adsorbent area, may be made higher than the case where the entire surface of the surface is covered with the adsorbent.

The hydrogen exhaust efficiency may be 5 × 10 ⁻² L / s · mm ² or more. At least 10% of the total surface area of the cryopanel substrate may be an adsorbent deletion zone. At least 90% of the adsorbent may be exposed to the radiation shield or the shield opening.

A method according to one embodiment is obtained by obtaining a value of a panel structural parameter giving a maximum hydrogen exhaust rate when the panel structural parameter is changed under a condition in which an adsorbent is dropped from a part of the surface of the cryosorbent panel. And determining the configuration of the cryo sorption panel array based on the value of the structural parameter. The panel structure parameters may include the dimensions of the cryosorbent panel.

FIG. 1: is a figure which shows typically the ion implantation apparatus 1 and the cryopump 10 which concerns on one Embodiment of this invention. The ion implantation apparatus 1 as an example of the beam irradiation apparatus for irradiating a beam to a target includes an ion source unit 2, a mass spectrometer 3, a beam line unit 4, and an end station. It comprises a part 5.

The ion source portion 2 is configured to ionize an element to be injected onto the substrate surface and extract it as an ion beam. The mass spectrometer 3 is provided downstream of the ion source portion 2 and is configured to select necessary ions from the ion beam.

The beam line section 4 is provided downstream of the mass spectrometer 3, and includes a lens system for shaping an ion beam, and a scanning system for scanning an ion beam against a substrate. The end station part 5 is provided downstream of the beam line part 4, and is provided with a substrate holder (not shown) for supporting the substrate 8 to be the object of ion implantation, that is, the irradiation target, and the substrate (not shown). 8) and a drive system for driving. The beam path 9 in the beam line part 4 and the end station part 5 is typically shown by the broken-line arrow.

In addition, a vacuum exhaust system 6 is provided in the ion implantation apparatus 1. The vacuum exhaust machine 6 is provided to maintain the desired high vacuum (for example, high vacuum of about 10 ^-5 Pa) from the ion source portion 2 to the end station portion 5. The vacuum exhaust machine 6 includes cryopumps 10a, 10b, 10c.

For example, the cryopumps 10a and 10b are attached to the cryopump mounting openings on the wall surface of the vacuum chamber of the beam line section 4 for the vacuum exhaust of the vacuum chamber of the beam line section 4. The cryopump 10c is attached to the cryopump mounting opening of the vacuum chamber wall surface of the end station part 5 for the vacuum exhaust of the vacuum chamber of the end station part 5. However, the vacuum exhaust machine 6 may be comprised so that the beam line part 4 and the end station part 5 may exhaust | exhaust with one cryopump 10, respectively. Moreover, the vacuum exhaust machine 6 may be comprised so that the beam line part 4 and the end station part 5 may be exhausted by the some cryopump 10, respectively.

The cryopumps 10a and 10b are attached to the beam line portion 4 via gate valves 7a and 7b, respectively. The cryopump 10c is attached to the end station part 5 via the gate valve 7c. However, hereinafter, the cryopumps 10a, 10b, and 10c are collectively referred to as cryopumps 10, and the gate valves 7a, 7b, and 7c are collectively referred to as gate valves 7. During the operation of the ion implantation device 1, the gate valve 7 is open and exhausting by the cryopump 10 is performed. When regenerating the cryopump 10, the gate valve 7 is closed.

However, the vacuum exhaust machine 6 may further be provided with a turbomolecular pump and a dry pump for making the ion source unit 2 high vacuum. In addition, the vacuum exhaust machine 6 parallels the cryopump 10 with the roughing pump for exhausting the beam line portion 4 and the end station portion 5 from the atmospheric pressure to the operation start pressure of the cryopump 10. It may be provided as.

The gas present in the beam line portion 4 and the end station portion 5 and the gas introduced are exhausted by the cryopump 10. Most of these exhaust gases are usually hydrogen gas. Using the cryopanel of the cryopump 10, the exhaust gas containing hydrogen gas is exhausted from the beam path 9. However, the exhausted body may contain a discharge gas from a resist applied to a substrate, a dopant gas, or a negative gas generated in an ion implantation process.

The ion implantation apparatus 1 includes a main controller 11 for controlling the apparatus. In addition, the cryopump 10 is provided with a cryopump controller (hereinafter simply referred to as "CP controller") 100 for controlling the cryopump 10. The main controller 11 may be referred to as a higher controller that integrates the cryopump 10 through the CP controller 100. The main controller 11 and the CP controller 100 each include a CPU which executes various arithmetic operations, a ROM which stores various control programs, a RAM used as a work area for storing data or executing programs, an input / output interface, a memory, and the like. Equipped. The main controller 11 and the CP controller 100 are communicatively connected to each other.

The CP controller 100 is provided separately from the cryopump 10 and controls the plurality of cryopumps 10, respectively. Each cryopump 10a, 10b, 10c may be provided with an IO module (not shown) for processing input / output communicating with the CP controller 100, respectively. However, the CP controller 100 may be provided separately in each of the cryopumps 10a, 10b, and 10c.

The cryopump 10 for the ion implantation apparatus 1 exhausts hydrogen gas mainly as mentioned above. In order to increase the throughput of the ion implantation process of the ion implantation apparatus 1, a cryopump 10 capable of exhausting hydrogen gas at a high speed is required. In addition, there is a need for a cryopump that is excellent in improving the exhaust efficiency of hydrogen and further saving energy. Thus, the cryopump 10 has an adsorption zone for non-condensable gas that is formed substantially unexposed in the exposed cryosorption panel array 14.

2 is a cross-sectional view schematically showing a cryopump 10 according to an embodiment of the present invention. 3 is a top view of the cryopump 10 according to the preferred embodiment. 4 is a cross-sectional view schematically showing a cryopump 10 according to a preferred embodiment.

The exposed cryopanel array 14 forms a cryopump internal open space 30 that is open to the cryopump opening 31 between its outer periphery and the radiation shield 16. The open local space 54 is defined by the cryopanel 50 adjacent to each other in the cryopanel array 14, and the local space 54 is continuous in the open space 30 inside the cryopump. have. The adsorption region is formed on the surface of the cryopanel 50 surrounding the local space 54. This openness of the local space 54 promotes the arrival of gas into the adsorption region, thereby supporting the realization of high velocity exhaust of non-condensable gas such as hydrogen by the cryopump 10.

At least a portion of the open local space 54 is shielded from the cryopump opening 31 by the adjacent cryopanel 50, so that the adsorption region is accommodated in the local space 54. By avoiding the direct exposure of the adsorption zone to the cryopump opening 31, the adsorption zone is protected from the regeneration gas contained in the gas entering the cryopump 10. In this way, the high speed exhaust of the non-condensable gas and the protection of the adsorption region from the regenerating gas can be made compatible.

The cryopump 10 includes a first cryopanel cooled to a first cooling temperature level, and a second cryopanel cooled to a second cooling temperature level lower than the first cooling temperature level. The first cryopanel captures gas having a low vapor pressure at the first cooling temperature level by condensation. For example, a gas having a vapor pressure lower than the reference steam pressure (for example, 10 ⁻⁸ Pa) is exhausted.

Since the second cryopanel is a sorption panel and has a high vapor pressure, adsorption of non-condensable gas, which is not condensed even at the second cooling temperature level, is captured. As a result, all or most of the panel surface is the adsorption area. The adsorption zone is formed, for example, by forming an adsorbent on the panel surface. The adsorbent is for example activated carbon. The adsorption region may use an adsorbent such as zeolite, which is formed to selectively adsorb specific gas molecules, or may be a porous surface layer formed on the panel substrate as described above. The non-condensable gas is adsorbed into the adsorption zone cooled to the second cooling temperature level and exhausted. The non-condensable gas contains hydrogen. When a gas having a low vapor pressure is present in the atmosphere at the second cooling temperature level, it is captured by condensation on the adsorbent of the sorption panel or on the surface without the adsorbent.

The cryopump 10 includes a refrigerator 12. The refrigerator 12 generates cold by a heat cycle in which the working gas is sucked, expanded and discharged therein. The refrigerator 12 is a Gifford-Macma blend refrigerator (so-called GM refrigerator). In addition, the refrigerator 12 is a two-stage freezer, which includes a first stage cylinder 18, a second stage cylinder 20, a first cooling stage 22, a second cooling stage 24, and a refrigerator motor 26. Has The first stage cylinder 18 and the second stage cylinder 20 are connected in series, and a first stage displacer and a second stage displacer (not shown) connected to each other are incorporated. An inside of a 1st stage displacer and a 2nd stage displacer is equipped with the cooling material. However, the refrigerator 12 may be a refrigerator other than a two stage GM refrigerator, for example, may use a single stage GM refrigerator, or may use a pulse tube refrigerator or a Solvay refrigerator.

The refrigerator 12 includes a flow path switching mechanism for periodically switching the flow path of the working gas in order to periodically repeat the suction and discharge of the working gas. The flow path switching mechanism includes, for example, a valve portion and a drive portion for driving the valve portion. The valve portion is, for example, a rotary valve, and the driving portion is a motor for rotating the rotary valve. The motor may be, for example, an AC motor or a DC motor. In addition, the flow path switching mechanism may be a linear mechanism driven by a linear motor.

A refrigerating motor 26 is provided at one end of the first stage cylinder 18. The refrigerator motor 26 is provided inside the motor housing 27 formed at the end of the first stage cylinder 18. The refrigerator motor 26 may include a first stage displacer and a first stage displacer such that each of the first stage displacer and the second stage displacer allows the inside of the first stage cylinder 18 and the second stage cylinder 20 to reciprocate. It is connected to a two stage displacer. In addition, the refrigerator motor 26 is connected to the valve so that the movable valve (not shown) provided in the motor housing 27 can be rotated forward and backward.

The 1st cooling stage 22 is provided in the edge part by the side of the 2nd end cylinder 20 of the 1st end cylinder 18, ie, the connection part of the 1st end cylinder 18 and the 2nd end cylinder 20. As shown in FIG. In addition, the second cooling stage 24 is provided at the end of the second stage cylinder 20. The first cooling stage 22 and the second cooling stage 24 are fixed to the first stage cylinder 18 and the second stage cylinder 20, for example, by brazing.

The refrigerator 12 is connected to the compressor 102 through the gas supply port 42 and the gas discharge port 44 provided outside the motor housing 27. The refrigerator 12 expands the high-pressure working gas supplied from the compressor 102 (for example, helium, etc.) to generate cold in the first cooling stage 22 and the second cooling stage 24. The compressor 102 recovers the working gas expanded in the refrigerator 12, pressurizes it again, and supplies the same to the refrigerator 12.

Specifically, a high pressure working gas is first supplied from the compressor 102 to the refrigerator 12. At this time, the refrigerator motor 26 drives the movable valve inside the motor housing 27 in a state where the gas supply port 42 and the internal space of the refrigerator 12 communicate with each other. When the internal space of the refrigerator 12 is filled with a high-pressure working gas, the movable valve is switched by the refrigerator motor 26 so that the internal space of the refrigerator 12 communicates with the gas outlet 44. As a result, the working gas is expanded and returned to the compressor 102. In synchronization with the operation of the movable valve, each of the first stage displacer and the second stage displacer reciprocates the interior of the first stage cylinder 18 and the second stage cylinder 20. By repeating such a heat cycle, the refrigerator 12 generates cold in the first cooling stage 22 and the second cooling stage 24.

The second cooling stage 24 is cooled to a lower temperature than the first cooling stage 22. The second cooling stage 24 is cooled, for example, by about 10K to 20K, and the first cooling stage 22 is cooled by, for example, about 80K to 100K. The first cooling stage 22 is equipped with a first temperature sensor 23 for measuring the temperature of the first cooling stage 22, and the second cooling stage 24 is equipped with a temperature of the second cooling stage 24. The second temperature sensor 25 for measuring the temperature is mounted.

The radiation shield 16 is fixed to the first cooling stage 22 of the refrigerator 12 in a thermally connected state, and the cryopanel assembly 14 is thermally connected to the second cooling stage 24 of the refrigerator 12. It is fixed in the connected state. As a result, the radiation shield 16 is cooled to the same temperature as the first cooling stage 22, and the cryopanel assembly 14 is cooled to the same temperature as the second cooling stage 24.

The CP controller 100 (see FIG. 1) determines the control output based on the sensor output signal. The CP controller 100 determines, for example, the voltage and frequency to be supplied to the refrigerator motor 26. The CP controller 100 controls an inverter (not shown) installed in the refrigerator motor 26. The inverter of the refrigerator motor adjusts the power of a prescribed voltage and frequency supplied from an external power source, such as a commercial power source, and supplies it to the refrigerator motor 26 in accordance with a command from the CP controller 100.

The CP controller 100 controls the refrigerator 12 based on, for example, the temperature of the cryopanel. The CP controller 100 gives an operation command to the refrigerator 12 so that the actual temperature of the cryopanel follows the target temperature. For example, the CP controller 100 controls the operating frequency of the refrigerator motor 26 by feedback control so as to minimize the deviation between the target temperature of the first cryopanel and the measured temperature of the first temperature sensor 23. The frequency of the heat cycle of the refrigerator 12 is determined according to the operating frequency of the refrigerator motor 26. The target temperature of the first cryopanel is determined as a specification, for example, in accordance with a process performed in the vacuum chamber 80. In this case, the second cooling stage 24 and the cryopanel assembly 14 of the refrigerator 12 are cooled to a temperature determined according to the specifications of the refrigerator 12 and the heat load from the outside.

When the measured temperature of the first temperature sensor 23 is higher than the target temperature, the CP controller 100 outputs a command value to increase the operating frequency of the refrigerator motor 26. In association with the increase in the motor operating frequency, the frequency of the heat cycle in the refrigerator 12 is also increased, and the first cooling stage 22 of the refrigerator 12 is cooled toward the target temperature. On the contrary, when the measured temperature of the first temperature sensor 23 is lower than the target temperature, the operating frequency of the refrigerator motor 26 is decreased and the first cooling stage 22 of the refrigerator 12 is heated up toward the target temperature. .

Usually, the target temperature of the 1st cooling stage 22 is set to a fixed value. Therefore, the CP controller 100 outputs a command value to increase the operating frequency of the refrigerator motor 26 when the heat load to the cryopump 10 increases, and when the heat load to the cryopump 10 decreases. The command value is output to reduce the operating frequency of the refrigerator motor 26. However, the target temperature may be appropriately varied, for example, the target temperature of the cryopanel may be set sequentially so that the target atmosphere pressure is realized in the exhaust target volume (for example, the vacuum chamber 80). In addition, the CP controller 100 may control the operating frequency of the refrigerator motor 26 to match the measured temperature of the second cryopanel to the target temperature.

In a typical cryopump, the frequency of the heat cycle is always constant. It is set to operate at a relatively large frequency to enable rapid cooling from the normal temperature to the pump operating temperature, and when the heat load from the outside is small, the temperature of the cryopanel is adjusted by heating by a heater. Therefore, power consumption increases. In contrast, in the present embodiment, since the heat cycle frequency is controlled according to the heat load on the cryopump 10, the cryopump excellent in energy saving can be realized. In addition, the necessity of providing a heater necessarily contributes to the reduction of power consumption.

The cryopump 10 includes a cryopanel assembly 14 or a cryopanel structure. The cryopanel assembly 14 includes a plurality of cryopanels cooled by the second cooling stage 24 of the refrigerator 12. These panels are arranged inward from the opening side, ie from the opening side in the radiation shield 16. Each cryopanel has a front surface facing the shield opening 31 and a back surface opposite to the shield opening 31, that is, the closure portion 28. The cryopanel assembly 14 may include a cryopanel facing the side of the radiation shield 16 or a cryopanel (not shown) facing in the other direction. The surface of the panel is formed with a cryogenic surface for trapping and exhausting gas by condensation or adsorption. The surface of the cryopanel is usually provided with an adsorbent such as activated carbon for adsorbing gas.

The cryopanel assembly 14 forms an internal space 30 opened by the shield opening 31 between the outer circumferential portion and the radiation shield 16. The cryopanel assembly 14 can visually recognize at least a part of the outer circumferential portion of the cryopanel assembly 14 from the shield front end 33. The cryopump 10 shown in FIG. 2 and the cryopump 10 shown in FIGS. 3 and 4 differ in specific form of the cryopanel assembly 14. Details of the configuration of each cryopanel assembly 14 will be described later.

The cryopump 10 includes a radiation shield 16. The radiation shield 16 is provided to protect the cryopanel assembly 14 from surrounding radiant heat. The radiation shield 16 is formed in the shape of a bottomed cylinder having a shield opening 31 at one end. The shield opening 31 is defined by the shield front end 33 of the radiation shield 16, for example by the end inner surface of the cylindrical side surface. The shield front end 33 forms an opening for receiving gas from the vacuum chamber 80 to the cryopanel assembly 14.

On the other hand, the obstruction part 28 is formed in the other end of the radiation shield 16 on the opposite side to the shield opening 31, the pump bottom side. The closure portion 28 is formed by a flange portion that extends inward in the radial direction at the pump bottom side end portion of the cylindrical side of the radiation shield 16. Since the cryopump 10 shown in FIG. 2 is a so-called vertical cryopump, this flange part is attached to the 1st cooling stage 22 of the refrigerator 12. The refrigerator 12 protrudes into the inner space 30 along the central axis of the radiation shield 16, and the second cooling stage 24 is inserted into the inner space 30.

The so-called horizontal cryopump shown in FIG. 4 is the second unit of the refrigerator in the direction intersecting with the axial direction of the radiation shield 16 (usually orthogonal and in FIG. 4 from the inside of the ground to the front). The cooling stage 24 is inserted and arrange | positioned. In the case of the horizontal type, the obstruction part 28 is normally completely occluded. The refrigerator 12 protrudes from the opening for attaching the refrigerator formed on the side surface of the radiation shield 16 to the internal space 30 along the direction orthogonal to the central axis of the radiation shield 16. The first cooling stage 22 of the refrigerator 12 is mounted in the freezer mounting opening of the radiation shield 16, and the second cooling stage 24 of the refrigerator 12 is disposed in the internal space 30. The cryopanel assembly 14 is mounted to the second cooling stage 24. In this way, the cryopanel assembly 14 is disposed in the inner space 30 of the radiation shield 16.

2 to 4, a baffle or louver 32 thermally connected to the radiation shield 16 is provided at the shield opening 31 of the radiation shield 16. The louver 32 and the radiation shield 16 are arranged coaxially, and a ring-shaped open area 35 is formed between the outer circumferential portion of the louver 32 and the radiation shield 16. The louver 32 is provided with the cryopanel assembly 14 at intervals in the central axis direction of the radiation shield 16. However, a gate valve 7 (see FIG. 1) is provided between the louver 32 and the vacuum chamber 80.

As shown in FIG. 3, the louver 32 is attached to the radiation shield 16 by the mounting structure 37. The mounting structure 37 is installed in four places, for example at intervals of 90 degrees. The mounting structure 37 mechanically fixes the louver 32 to the radiation shield 16 and also functions as a heat transfer path from the radiation shield 16 to the louver 32.

The louvers 32 are formed of a plurality of wing plates 38, and each wing plate 38 is formed in the shape of a side surface of a cone having a diameter different from each other and arranged in a concentric shape. In FIG. 3, although there exists a gap between each wing plate 38, each wing plate 38 may be arrange | positioned so that there may be no gap when the adjacent wing plates 38 overlap each other and are seen from above. Each wing plate 38 is mounted to a cross-shaped support member 39, and the support member 39 is mounted to the mounting structure 37. As shown in FIG. When the louver 32 is viewed from the vacuum chamber 80 side, the louver 32 may be formed in a concentric shape, for example, or may be formed in another shape such as a lattice shape.

The area of the open area 35 is set so that the hydrogen exhaust rate by the cryopump 10 can realize the required specifications. Specifically, for example, by changing the number of blade plates 38 of the louver 32, the diameter of the louver 32 can be changed to adjust the area of the open area 35. An exposed portion, such as a peripheral edge, of the cryopanel assembly 14 that is not shielded by the louver 32 is visible from the outside through the open area 35.

The cryopump 10 is attached to the vacuum chamber 80 by a pump case 34. The vacuum chamber 80 is, for example, a vacuum chamber of the beam line portion 4 or the end station portion 5 (see FIG. 1). The cryopump 10 is hermetically fixed to the exhaust opening of the vacuum chamber 80 through the flange portion 36 of the pump case 34 to form an airtight space integral with the internal space of the vacuum chamber 80. do.

The pump case 34 accommodates the radiation shield 16, the louver 32, the cryopanel assembly 14, and the first cooling stage 22 and the second cooling stage 24 of the refrigerator 12. . The pump case 34 and the radiation shield 16 are both formed in a cylindrical shape and are arranged coaxially. Since the inner diameter of the pump case 34 slightly exceeds the outer diameter of the radiation shield 16, the radiation shield 16 is disposed with a slight gap between the inner surface of the pump case 34 and the inner side of the pump case 34. As shown in FIG.

The pump case 34 is formed by connecting two cylinders of different diameters in series. The large diameter cylindrical side end part of the pump case 34 is opened, and the flange part 36 for connection with the vacuum chamber 80 extends radially outward. Therefore, the large diameter end part of the pump case 34 defines the cryopump opening 31 for receiving gas from the exterior of the cryopump, for example, the vacuum chamber 80. The small cylindrical end portion of the pump case 34 is fixed to the motor housing 27 of the refrigerator 12.

The cryopanel assembly 14 is disposed in the inner space 30 of the radiation shield 16. The cryopanel assembly 14 includes a plurality of cryopanels 50 and a panel mounting member 52. The cryopanel assembly 14 includes a combination of heterophasic or different diameter cryopanels.

The panel mounting member 52 arranges a plurality of cryopanels 50 in a fixed manner according to the designed panel layout, and transfers heat from the second cooling stage 24 of the refrigerator 12 to each cryopanel 50. It is an element that constitutes. The panel mounting member 52 is, for example, a member having a bottom surface for mounting on the second cooling stage 24 and a side surface for fixing the plurality of cryopanels 50. The bottom face of the panel mounting member 52 faces the pump opening side, and the side surface surrounds the second cooling stage 24.

The plurality of cryopanels 50 are arranged inward from the front close to the shield opening 31. Each cryopanel 50 extends parallel to one another toward the side of the radiation shield 16. In the cryopanel 50, the distance between adjacent cryopanel becomes the same and is arranged evenly. The plurality of cryopanels 50 include a plurality of large cryopanels and a plurality of small cryopanels. 3 and 4, a plurality of larger cryopanels are included. The small cryopanel has a shape that is enclosed by the appearance of the large cryopanel. The cryopanel outer circumferential end protrudes radially from the shield central axis toward the open space 30. An open space 30 extends between the outer peripheral end of the cryopanel and the side surface of the radiation shield 16, and the open space 30 continues directly to the open area 35 around the louver 32.

Hereinafter, the cryopanel which contacts the cryopump opening 31 may be called a top panel. That is, the cryopanel closest to the cryopump opening 31 is the top panel. In FIG. 2, the top panel is a large cryopanel, but as shown in FIG. 4, the top panel may be a small cryopanel. The top panel may be one cryopanel or may be a generic term for some cryopanel closest to the cryopump opening 31.

In the embodiment shown in FIG. 2, the large cryopanel and the small cryopanel are alternately arranged at intervals. That is, the small cryopanel is adjacent to the large cryopanel, and the next large cryopanel is adjacent to the small cryopanel. The outer circumferential end of the large cryopanel extends to a position closer to the radiation shield 16 than the outer circumferential end of the small cryopanel. The louver 32 may have an intermediate size between a large cryopanel and a small cryopanel.

On the other hand, in the preferred embodiment shown in Figs. 3 and 4, the plurality of cryopanel 50 of the cryopanel assembly 14 is divided into a plurality of groups according to the dimensions, the group is a radiation shield ( 16) are arranged inward from the front.

In this embodiment, it is divided into three groups of 1st-3rd in order from the side closer to the shield opening 31, The larger the inner group is. Therefore, the first group of cryopanels is called the top panel or the small cryopanel 60, the second group of cryopanels is called the middle panel or the medium cryopanel 62, and the third group of cryopanels is called the cryopanel. The lower panel or the large cryopanel 64 is hereinafter referred to as appropriate. However, in this embodiment, although divided into three groups, the cryopanel assembly 14 may be provided with two groups, and may be provided with more than three groups.

Each group includes at least one cryopanel, preferably each group comprises a plurality of cryopanels. In one embodiment, each group has two to five cryosorbent panels, and the cryopanel assembly 14 has a total of eight to fourteen cryosorbent panels. In FIG. 4, the small cryopanel 60, the medium cryopanel 62, and the large cryopanel 64 are three sheets, four sheets, and three sheets, respectively.

The medium size cryopanel 62 is disposed on the side opposite to the shield opening 31 with respect to the small cryopanel 60. The large cryopanel 64 is disposed on the side opposite to the shield opening 31 with respect to the medium cryopanel 62. The outer circumferential portion of the medium size cryopanel 62 extends parallel to the small cryopanel 60 and to a position closer to the radiation shield 16 than the outer circumference of the small cryopanel 60. The outer circumferential portion of the large cryopanel 64 extends parallel to the medium cryopanel 62 and to a position closer to the radiation shield 16 than the outer circumferential portion of the medium cryopanel 62. As shown in FIG. 3, the louver 32 may have an intermediate size between the small cryopanel 60 (indicated by broken lines in FIG. 3) and the medium cryopanel 62.

In one embodiment, each cryopanel 50 has a disc shape. In this case, the plurality of cryopanel 50 includes a large diameter original panel, a small diameter original panel, and a medium diameter original panel. The louver 32 may be a disc shaped louver having a diameter between the disc panel of medium diameter and the disc panel of small diameter. In the embodiment shown in FIG. 2, the louver 32 may be a disc-shaped louver having a diameter between the large diameter disc panel and the small diameter disc panel.

Each of the plurality of cryosorption panels 50 is, for example, a plate of metal including a front face facing the shield opening 31 or the louver 32 and a back face facing the closure portion 28 on the opposite side. Activated carbon adheres to the surface of the plate to form an adsorption region. At least 50% of the total area of the front and back surfaces is an adsorption area, and at most 50% of the rest is a non-adsorption area. The non-adsorption area is an adsorbent missing zone in which the metal surface of the plate on which the adsorbent is not formed is exposed. This adsorbent missing zone can function as a condensation zone.

The entire back surface of each cryopanel 50 may be an adsorption region, and at least a part of the front surface of the cryopanel 50 may also be an adsorption region. In the top cryopanel, only the rear surface may have an adsorption area. In the embodiment shown in Fig. 2, for example, the front surface of at least the large cryopanel of the lower cryopanel 50 excluding the uppermost cryopanel is the adsorption region, and the outside thereof is the nonadsorption region or the condensation. It may be an area. The entire surface of the small cryopanel among the lower cryopanel 50 may be an adsorption region. The entire front surface of some of the lowermost cryopanels may be an adsorption area.

The boundary between the adsorption zone and the non-adsorption zone, that is, the boundary between the missing zone and the presence zone of the adsorbent may be determined according to the trajectory of the line of sight projected on the front surface of the cryopanel. This line of sight is a straight line drawn from the shield front end 33 in the outer peripheral end of the cryopanel one ahead. In other words, the line where the line of sight intersects the front of the panel becomes a boundary line. An adsorption region is formed inside the boundary line, and preferably the adsorption region is occupied inside the boundary. In addition, the condensation zone comprises a zone outside the boundary, and is preferably defined outside the boundary. In this way, the outer periphery of the front surface of the cryopanel 50 is divided into an adsorption zone and a condensation zone.

FIG. 5 is a diagram for explaining the adsorption region formed in the cryopanel 50 as related to the cryopump shown in FIG. 4. In FIG. 5, it is illustrated with a broken arrow to illustrate the first line of sight 70 and the second line of sight 72 from the shield front end 33. The first line of sight 70 is a line of sight to the outer end of the small cryopanel 60 farthest from the shield opening 31 or the shield front end 33. The second line of sight 72 is the line of sight to the outer end of the medium-sized cryopanel 62 closest to the shield opening 31 or the shield front end 33. As described above, the small cryopanel 60 farthest from the shield opening 31 and the medium cryopanel 62 closest to the shield opening 31 are adjacent to each other.

The trajectory of the first line of sight 70 on the front surface of the medium size cryopanel 62 closest to the shield opening 31 is condensed with the adsorption region 74 on the front surface of the medium size cryopanel 62. The boundary 84 of the area 78 is given. Further, the trajectory of the second line of sight 72 on the front surface of the medium size cryopanel 62 closest to the shield opening 31 is the adsorption area on the front surface of the medium size cryopanel 62. 76 and the boundary 86 of the condensation zone 82. Similarly, the boundary between the adsorption region and the condensation region can be determined for the remaining medium cryopanel 62, the small cryopanel 60, and the large cryopanel 64.

FIG. 6: is a top view which shows the front panel of the cryopanel 50 regarding the cryopump 10 shown in FIG. 4 and FIG. In the cryopanel 50, a cutout portion 88 is formed from a portion of the outer circumference to the center portion for attachment to the panel mounting member 52. As an example, FIG. 6 shows a boundary line 86 determined by the second line of sight 72 of FIG. 5. Corresponding to the shield opening 31 and the cryopanel 50 being circular, the boundary line 86 also draws a circle on the front surface of the panel. In this case, the boundary line 86 represents the adhesion limit radius of the adsorbent. By adhering the adsorbent to the entire inner side of the bonding limit radius, the most adsorbent can be mounted on the entire panel surface without exposing the adsorbent from the shield opening 31.

FIG. 7: is a figure which shows the back surface of the cryopanel 50 shown in FIG. As mentioned above, an adsorbent may be adhere | attached on the whole surface of a panel, and as shown in FIG. Such narrow adsorbent missing zones may be provided, for example, to ensure that the shield opening 31 is not exposed in consideration of the height of particles of adsorbent such as activated carbon.

In this way, the cryosorbent panel 50 has an adsorbent missing zone formed on the same plane as the adsorbent presence zone. The common face is, for example, a plane, and more specifically, the panel front or panel back. The adsorbent deletion zone exposes the cryopanel substrate surface, such as a metal surface, for cryo condensation. The adsorbent missing zone is at the peripheral edge exposed portion that is visible through the cryopump opening 31.

The particles of activated carbon adhered to the cryopanel 50 are formed into, for example, a columnar shape. Particles of a plurality of activated carbons are adhered in an irregular arrangement in a state in which the particles are arranged on the surface of the cryopanel 50. However, the shape of the adsorbent may not be columnar, for example, may be a spherical shape, other molded shape, or irregular shape. The arrangement on the panel of the adsorbent may be a regular arrangement or an irregular arrangement.

2 and 4, at least 60% or at least 70% of the total area of the front and back surfaces of the plurality of cryopanels 50 is covered with the adsorbent. Preferably, at least 90% or at most 80% of the total area of the front and back surfaces of the plurality of cryopanel 50 is set by using the center of the cryopanel 50 at least upward (opening side) as the adsorbent presence zone. Covered with adsorbent. 65 to 85% of the total area of the front and rear surfaces of the plurality of cryopanel 50 may be covered with an adsorbent.

2 and 4, at least 40% or at most 30% of the total area of the front and back surfaces of the plurality of cryopanels 50 is a zone in which the adsorbent is missing. Preferably, at least 10% or at least 20% of the total area of the front and rear surfaces of the plurality of cryopanels 50 is obtained by making the outer peripheral portion of the cryopanel 50 at least upward (opening side) the adsorbent missing zone. Adsorbent missing zone. 15 to 35% of the total area of the front and rear surfaces of the plurality of cryopanels 50 may be an adsorbent elimination zone.

In particular, in the cryopanel assembly 14 including the medium cryopanel 62, at least 60% or at least 70% of the total surface area of the medium cryopanel 62 is preferably covered with an adsorbent. At least 60% or at least 70% may be covered with an adsorbent with respect to each surface of each panel of the medium size cryopanel 62. At least 60% or at least 70% may be covered with an adsorbent with respect to both surfaces of each panel or as a total of plural panels. In addition, it is preferable that 90% or less or 80% or less of the total surface area of the medium size cryopanel 62 is covered with an adsorbent by making the outer peripheral part an adsorbent missing zone. More preferably, the medium size cryopanel 62 has an adsorbent coverage of 65 to 85%.

In this case, the small cryopanel 60 preferably has the same adsorbent coverage as the medium cryopanel 62 or smaller than the medium cryopanel 62. For example, the small cryopanel 60 preferably has an adsorbent coverage of 50 to 65%. The large cryopanel 64 preferably has the same adsorbent coverage as the midsize cryopanel 62 or greater than the midsize cryopanel 62. For example, the large cryopanel 64 preferably has an adsorbent coverage of 85 to 100%. In the large cryopanel 64, the entire surface of both surfaces may be covered with an adsorbent.

8 and 9 are tables showing an example of an adsorbent dropping rate or a covering rate of the cryopanel assembly 14 according to the embodiment of the present invention. Each of the small cryopanel 60, the medium cryopanel 62, and the large cryopanel 64 shows the loss rate and coverage of the adsorbent. The loss rate and coverage are shown for both the individual plates and the sum of the groups. Fig. 8 shows each of the front side and the back side, and Fig. 9 shows the sum of the front side and the back side.

In FIG. 8 and FIG. 9, the small cryopanel 60, the medium cryopanel 62, and the large cryopanel 64 are denoted as group 1, group 2, and group 3, respectively. In the present embodiment, the group 1, group 2, and group 3 include 10 plates in total, including three, four, and three plates, respectively. These plates are arranged in the same manner as the cryopanel assembly 14 shown in FIG. In FIG. 8, the number 10 is attached | subjected from plate number 1, respectively.

In this embodiment, each plate is a metal, the adsorbent is granular activated carbon, and the activated carbon is adhered to the metal surface with an adhesive. Therefore, the area of the metal part shown in FIG. 8 represents the area of each of the front and rear surfaces of the plate. The area of the activated carbon is zero when no activated carbon is formed on the surface thereof. The area of the activated carbon is equal to the area of the metal portion when the entire surface is covered by the activated carbon. . The ratio of the area of the activated carbon part to the area of the metal part is the coverage, and the ratio of the remaining area to the area of the metal part is the loss rate.

However, all three plates of the small cryopanel 60 are the same diameter. The top plate (plate number 1) closest to the opening of the group 1 has a larger area than the plates immediately below it (plate numbers 2 and 3), as shown in FIG. Whereas the top plate does not have. That is, the area of the top plate is larger by an area corresponding to the cutout 88.

As with the embodiment shown in FIG. 6, activated carbon is bonded to the front surface of the plate inside the boundary defined by the intersection of the front surface of the plate and the line of sight from the shield front end 33 to the adjacent plate end on the front side thereof. . However, activated carbon is not formed on the front surface of the top plate (plate number 1) closest to the opening of the group 1, and the metal surface is exposed. Also with respect to the plate immediately below it (plate number 2), the activated carbon is not formed in the whole surface, but the metal surface is exposed. This is because the line of sight from the shield front end 33 and the plate surface do not intersect (that is, the entire front surface is visible from the shield front end 33).

Activated charcoal occupies the entire region inside the boundary determined by the line of sight: the plate furthest from the opening of group 1 (plate number 3), the plate closest to the opening of group 2 (plate number 4), and 2 of group 2 The plate closest to the opening (plate number 5), the plate closest to the group 3 opening (plate number 8), and the plate closest to the second opening of the group 3 (plate number 9).

From production efficiency, two lower plates of two groups (plate number 6, 7) are made the same as the plate (plate number 5) just above, and the three lowest group plates (plate number 10) And the plate immediately above it (plate number 9). Therefore, these plates have an outer periphery of the actual activated carbon part slightly inside the boundary determined by the line of sight. Also for these plates, the boundary determined by the line of sight may coincide with the outer periphery of the actual activated carbon portion, and the activated carbon portion may be enlarged to some extent.

On the back of the plate, unlike the embodiment shown in FIG. 7, activated carbon is bonded to the entire area without forming an activated carbon missing section at the outer circumferential end. Therefore, the area of the back metal part and the area of the activated carbon part are the same.

In the subtotals of the groups shown in Fig. 9, the activated carbon coverage was increased in steps of 50% in Group 1, 77% in Group 2, and 87% in Group 3. In the whole cryopanel assembly 14, the activated carbon coverage is 76%.

As shown in FIG.2 and FIG.4, one back surface and the other front surface of two adjacent cryopanel 50 extend in parallel toward the side surface of the radiation shield 16, and the open part 54 therebetween. ) Is formed. The open portion 54 faces the radiation shield 16 and is continuous with the open space 30. The outer circumferential side of the open portion 54 is an inlet of gas continuous to the open space 30, and the inner circumferential side of the open portion 54 is formed by two adjacent cryopanel 50 and the panel mounting member 52. Occluded

The cryopanel 50 is arranged densely in the shield central axis direction so that the depth of the open portion 54 becomes larger than the distance between two adjacent cryopanel 50. The "depth" of the open portion 54 is the length in the in-plane direction of the cryopanel 50 and is the distance from the outer peripheral end of the cryopanel to the panel mounting member 52. In the case where two adjacent cryopanel 50 are different in size, the distance from the smaller cryopanel outer peripheral end to the panel mounting member 52 is the depth of the open portion 54. By such a compact panel arrangement, more adsorbents can be mounted in a limited space inside the cryopump.

Since an adsorption region is formed on the surface of the cryopanel 50 surrounding the open portion 54, at least 90% of the adsorbent, preferably substantially all of the adsorbent, is the radiation shield 16 or the shield opening 31. Is exposed toward). The gas molecules flying toward the cryopump 10 enter the internal open space 30 through the open area 35 around the louver 32. Non-condensable gases, such as hydrogen, reflect off the shield or panel surface and enter the open portion 54 to reach the adsorbent. The openness inside the cryopump leading from the open zone 35 to the open portion 54 through the open space 30 promotes the arrival of gas from the outside to the adsorption zone. In this way, the cryopump 10 having a high hydrogen trapping probability such as at least 30% is realized.

The hydrogen trapping probability is given by the ratio of the actual hydrogen exhaust rate to the theoretical maximum hydrogen exhaust rate in the cryopump having the same aperture as the cryopump 10 (that is, the same cryopump opening area). The actual hydrogen evacuation rate of the cryopump can be obtained by known Monte Carlo simulation.

In addition, the theoretical hydrogen exhaust velocity can be considered to be equal to the conductance of the molecular stream for that opening. The conductance C (hydrogen) of hydrogen is calculated | required from the conductance (C (20 degreeC air)) of 20 degreeC air by following Formula.

Where T is the temperature of hydrogen gas (K) and M is the molecular weight of hydrogen (ie, M = 2). The conductance C (20 ° C. air) of 20 ° C. air is given by C (20 ° C. air) = 116 A in proportion to the opening area A (m 2). For example, in the case of a cryopump with a diameter of 250 mm, the theoretical hydrogen exhaust rate is about 20840 L / s by the above formula. At this time, the hydrogen trapping probability is equal to 30%, and the hydrogen exhaust rate of the cryopump is about 6252 L / s.

A typical conventional cryopump for hydrogen high-speed exhaust is designed with the idea of increasing the exhaust rate by mounting more cryopanel, ie, activated carbon, in the cryopump. Therefore, the improvement of the exhaust speed, the increase of the panel weight, and the increase of the regeneration time (especially the cool down time) have a trade off relationship. In order to suppress the increase in cooldown time while increasing the exhaust speed, a refrigerator with high freezing capacity is required. Therefore, the energy saving performance can be sacrificed by the improvement of the exhaust speed.

In contrast, one embodiment of the present invention provides a new design idea of optimizing hydrogen exhaust efficiency in a cryopump for hydrogen fast exhaust. The present inventors have compared the ratio of the hydrogen exhaust rate (L / s) of the cryopump to the adsorption area area (mm2), that is, the exhaust rate per unit area of the adsorbent presence zone, and the hydrogen exhaust efficiency (L / s · mm2) of the cryopump. It is defined as Instead of simply increasing the adsorbent, the exhaustion efficiency is increased by making the area of the adsorption area smaller to some extent. As described above, the area of the adsorption area may be reduced in the outer portion of the cryopanel, or the area of the adsorption area may be reduced in the other parts.

If the area of adsorption area is made small to some extent, the hydrogen exhaust velocity of the cryopump will also be made to some extent small. However, it is considered that it is not really a problem in practice. Although the cryopump alone has a difference in the exhaust speed, the difference in the exhaust speed actually produced when the cryopump is actually mounted when the cryopump is actually operated tends to be smaller than that. This is because, due to the limitation by the conductance on the vacuum chamber side, the exhaust speed performance when viewed with the cryopump alone is not necessarily exhibited as it is.

According to the experiences and considerations of the present inventors, even though there was a 10% difference in the exhaust speed performance of the cryopump alone in the cryopump for hydrogen high-speed exhaust, Little effect. Therefore, when the allowable range for reducing the hydrogen exhaust rate is set within 10%, the advantage of improving the hydrogen exhaust efficiency by reducing the adsorption area area exceeds the disadvantage of reducing the exhaust rate. Therefore, in one embodiment of this invention, even if the adsorption area area is adjusted so that hydrogen exhaustion efficiency may be improved on condition that the exhaust velocity of at least 90% of the hydrogen exhaust rate when covering the entire cryopanel surface with the adsorbent is provided. do.

According to the analysis of the present inventors, for example, a cryopump having a panel arrangement of a plurality of flat plates parallel to the openings of the type shown in FIGS. 2 and 4 has a hydrogen exhaustion efficiency of 2 when the entire cryopanel surface is covered with an adsorbent. ^{× 10 -2 L / s · ㎟} ~ 4 × 10 -2 stays at about L / s · ㎟. On the other hand, by forming the missing part of an adsorbent like the Example shown to FIG. 2 and FIG. 4, hydrogen exhaust efficiency can be improved to 5x10 <^-2> L / s * mm <2> or more. Hydrogen exhaust efficiency can be raised to 7x10 <^-2> L / s * mm <^2> in the reduction tolerance range of hydrogen exhaust rate.

In other words, the hydrogen exhaustion efficiency is approximately doubled. This means that the hydrogen exhaust rate at the same level is realized in half the adsorption region. This can reduce the panel weight by about 1000 ~ 2000g. When the panel weight is reduced, the time required for cool down is also shortened. As a result, the average power consumption during reproduction can be reduced by approximately 40%.

However, in order to make hydrogen exhaustion efficiency higher than 7x10 <^-2> L / s * mm < ² >, the cryopanel assembly of the type which exposes an adsorbent completely (for example, refer patent document 4 (Unexamined-Japanese-Patent No. 2009-162074)). It would be realistic to employ it. The entirety of which is incorporated herein by reference in Japanese Patent Laid-Open No. 2009-162074.

By the way, the molecules of the condensable gas flying from the outside toward the cryopump 10 pass through the open area 35 around the louver 32 to form the outer circumference of the radiation shield 16 or the cryopanel 50. The condensation zones of them reach a straight path and are captured on their surface. The open local space 54 is shielded from the cryopump opening 31 by the cryopanel 50 on the upper side, except for the gas inlet on the outer circumferential side, and the adsorption area is accommodated in the shielding portion. I regenerate gas is a condensable gas with almost no exceptions. By avoiding the direct exposure of the adsorption zone to the cryopump opening 31, the adsorption zone is protected from the regeneration gas contained in the gas entering the cryopump 10. Regenerated gas is deposited in the condensation zone. In this way, the high speed exhaust of the non-condensable gas and the protection of the adsorption region from the regenerating gas can be made compatible.

In one embodiment of the present invention, the suction area is accommodated in the shielding portion, whereby it is impossible to see from the cryopump opening 31. In other words, the "adsorbent visibility rate" which is the ratio of the adsorbent area visible from the cryopump opening 31 with respect to the total area of the adsorbent of the cryopanel 50 is zero%. However, the cryopump according to one embodiment of the present invention is not limited to the configuration in which the adsorbent viewing rate is zero%. When the adsorbent visibility is less than 7%, the adsorbent may be substantially evaluated to be invisible from the opening. In one embodiment, the adsorbent visibility is preferably less than 7%, less than 5%, or less than 3%. However, if, for example, the content of the regeneration gas is expected to be sufficiently low, or if it is acceptable to sacrifice the exposed adsorbent, more than 7% of the adsorbent may be visible from the opening.

Compared to the cryopanel 50 close to the cryopump opening 31, gas molecules are less likely to reach the cryopanel 50 inside the radiation shield 16 away from the cryopump opening 31. The cryopanel 50 away from the cryopump opening 31 has a small contribution to the exhaust speed and a small influence of the regeneration gas. Therefore, in one embodiment, the lower large cryopanel 64 may have an adsorbent formed at the peripheral edge exposed portion. For example, in the Example shown in FIG. 8, when the adsorbent is formed in the whole front surface of the large cryopanel 64, the adsorbent visibility rate is about 7%.

The operation of the cryopump 10 will be described. In the operation of the cryopump 10, first, the inside of the vacuum chamber 80 is roughened to about 1 Pa to about 10 Pa using another suitable roughing pump before the operation. The cryopump 10 is then operated. The radiation shield 16, the louver 32, and the cryopanel assembly, in which the first cooling stage 22 and the second cooling stage 24 are cooled and thermally connected thereto by driving the refrigerator 12, 14) is also cooled. The first cryopanel described above includes a radiation shield 16 and a louver 32, and the second cryopanel includes a cryopanel assembly 14.

The cooled louver 32 cools gas molecules flying from the vacuum chamber 80 toward the cryopump 10, and condenses the gas (eg, moisture, etc.) whose vapor pressure is sufficiently low at the cooling temperature. To exhaust. At the cooling temperature of the louver 32, gas whose vapor pressure is not sufficiently lowered enters the radiation shield 16 through the louver 32. When the gas molecules passing through the louver 32 contain gas (for example, argon) whose vapor pressure is sufficiently lowered at the cooling temperature of the cryopanel assembly 14, it is condensed on the surface of the cryopanel assembly 14. Exhausted. The gas (for example, hydrogen, etc.) whose vapor pressure is not sufficiently lowered even at the cooling temperature is adsorbed by the adsorbent cooled on the surface of the cryopanel assembly 14 and exhausted. In this manner, the cryo pump 10 can reach the desired level of vacuum in the vacuum chamber 80.

In particular, in the cryopump 10 used in the vacuum exhaust machine of the ion implantation apparatus, among the gases entering the radiation shield 16, the regeneration gas such as organic gas or dopant gas is used in the cryopanel 50. It is condensed on the adsorbent missing part of the outer circumference. Gas having a relatively small molecular diameter such as hydrogen gas is adsorbed by the adsorbent. In this way, the cryopumping process is performed.

If the cryopumping process is performed continuously, gas will accumulate inside the cryopump. A regeneration process is performed to discharge the accumulated gas to the outside. First, the cryopump 10 is separated from the vacuum chamber 80 by closing the gate valve 7. Subsequently, the cryopanel 50 is heated up. The cryopanel 50 is heated to a higher temperature (for example, room temperature) than the cooling temperature in the cryopumping process.

By the temperature increase, the gas trapped by the condensation on the surface of the cryopanel is vaporized, and the gas trapped by the adsorption is desorbed and re-emitted into the pump container. The re-emitted gas is discharged to the outside through an outlet (not shown) of the cryopump 10, for example, by driving a roughing pump installed. Thereafter, the cryopanel 50 is recooled at the operating temperature in the cryopumping process. The regeneration process is completed by recooling. The gate valve 7 is opened, and the cryopumping process is started again. In this way, the cryopumping process and the regeneration process are performed alternately.

FIG. 10 relates to an embodiment of the present invention and shows a change in hydrogen exhaust rate of a cryopump through regeneration. FIG. 10 shows a change in the hydrogen exhaust rate of the cryopump 10 according to one embodiment of the present invention. For comparison, the hydrogen exhaust rate change for a cryopump having a cryopanel assembly of the type that completely exposes the adsorbent described in, for example, Japanese Patent Application Laid-Open No. 2009-162074 is shown. The vertical axis in FIG. 10 represents a measured value of the hydrogen exhaust rate, and the horizontal axis represents the number of regenerations. The measured exhaust velocity on the solid line is the value immediately before execution of the regeneration process, and the measured value on the dashed line is the value immediately after completion of the regeneration process.

The measured value on the broken line with respect to the first regeneration shown in FIG. 10 is a value when the cryopump was operated for the first time. Since activated carbon is not contaminated by the refractory gas, a particularly high hydrogen exhaust rate is shown in the fully exposed type of the comparative example.

The exhaust velocity is expected to be low just before regeneration and to recover after completion. However, in the comparative example, as shown, after the third regeneration, the decrease and recovery of the exhaust rate are repeated, but the exhaust rate is rapidly reduced from the initial high exhaust rate until the second regeneration. It is considered that the exhaust rate continued to decrease until the exposed activated carbon was contaminated to some extent. Even subsequent regeneration does not recover the initial exhaust performance.

However, in the embodiment, the increase and decrease of the exhaust speed is repeated from the first regeneration to the seventh regeneration. Even if the regeneration is repeated, the hydrogen exhaust velocity is substantially maintained at a constant level, as indicated by the thick broken line shown. Regeneration is restored to the initial exhaust performance. In other words, it can be seen that the exhaust performance is continuously maintained from the first operation immediately after the cryopump is shipped.

11 is a flowchart for explaining a method for manufacturing a cryopump 10 according to an embodiment of the present invention. This method is performed by an operator or a manufacturing apparatus in the manufacturing process of the cryopump 10. Prior to the masking process, a process of processing and molding the substrate of the cryopanel from the base material is performed (S10). As shown in FIG. 11, the masking process is given to the base material of the cryopanel 50 (S12). The masking process includes masking the exposed portion of the substrate that will not be shielded by another cryopanel (for example, an upper cryopanel adjacent when the cryopanel assembly 14 is assembled). Masking processing includes, for example, applying a masking tape to such exposed portions.

Next, an adsorbent adhesion treatment for adhering the adsorbent to the surface of the unmasked substrate is performed (S14). This adhesion treatment includes applying an adhesive to the surface of the unmasked substrate and adhering an adsorbent such as granular activated carbon to the adhesive application region. The adhered cryopanel 50 of the adsorbent is attached to the panel mounting member 52, and the cryopanel assembly 14 is assembled (S16). The cryopanel assembly 14 is mounted to the refrigerator 12 of the cryopump 10, and the cryopump 10 is assembled (S18).

In addition, prior to the masking process, the gaze from the front end of the radiation shield 16 to the end of the cryopanel 50 adjacent to the cryopanel 50 with respect to each cryopanel 50 and its cryo The outside of the boundary determined by the intersection of the panel 50 may be determined as the masking area. This crystallization process may be performed in the design process of the previous stage of a manufacturing process.

12 is a flowchart for explaining a method for manufacturing a cryopump 10 according to an embodiment of the present invention. This method is implemented, for example, to design the cryopanel assembly 14. First, the value of the cryopanel structure parameter giving the maximum hydrogen exhaust rate when the cryopanel structure parameter is changed under certain constraints is obtained (S20). Using the known experimental design method, the panel structural parameters may be obtained using the known experimental design method, with the panel structural parameters as variables.

Constraints include missing adsorbents from a portion of the surface of the cryosorbent panel. This adsorbent dropping condition is determined by the line of sight determined from the front end of the radiation shield 16 to the end of the cryopanel 50 adjacent to the cryopanel 50 and the intersection of the front surface of the cryopanel. It may be provided to form an adsorption region.

The panel structure parameters include the dimensions of the cryo sorption panel, such as the panel diameter when the panel is circular. When the cryopanel assembly 14 includes plural kinds of cryopanels of different shapes, a plurality of parameters for indicating respective shapes may be used. In the case where the cryopanel assembly 14 includes a plurality of kinds of cryopanels having different diameters, the panel structure parameters may include respective diameters. The panel structure parameter may include the distance between the cryopump opening 31 and the top panel. The panel structure parameter may include the diameter of the louver 32. The panel structure parameters may include the adjacent cryopanel spacing.

The configuration of the cryosorption panel array is determined based on the values of the panel structure parameters thus obtained (S22). For example, a value of a cryopanel dimension, such as a panel diameter, is obtained which gives a maximum hydrogen exhaust rate under conditions which result in the adsorbent being dropped from a part of the surface of the cryosorbent panel. This value can be used to determine the specific configuration of the cryopanel assembly 14.

In the above, this invention was demonstrated based on the Example. The present invention is not limited to the above embodiments, various design changes are possible, various modifications are possible, and it is understood by those skilled in the art that such modifications are also within the scope of the present invention.

You may employ | adopt the panel arrangement different from embodiment mentioned above. For example, the cryopanel spacing may be the same for all panels, or may be different from each other. For example, you may arrange | position each of the some panel 50 so that a panel space | interval narrows as the position of a panel moves away from the opening 31. FIG. By doing in this way, gas flowability in the area | region which adjoins the opening 31 can be made favorable, and exhaust velocity can be raised. At the same time, since the panels are densely arranged in a region far from the opening 31, the adsorption region can be increased, thereby ensuring sufficient gas storage amount.

In addition, you may employ | adopt the cryopanel 50 of a shape and / or orientation different from embodiment mentioned above. For example, the length in the radial direction of the panel 50 may be shortened as it moves away from the opening 31, or may be the same as each other. The shape when the panel 50 is seen from the opening 31 may not be circular, for example, may be another shape, such as a polygonal shape. The panel 50 may have, for example, a bent portion above or below the peripheral edge portion. The panel 50 may have openings or slits on the surface for promoting gas flow. The direction of the panel 50 may be inclined away from the opening 31 as it extends radially outward, or may be inclined so as to approach the opening 31 as it extends radially outward.

For example, an exposed surface other than the cryopanel 50 in the cryopanel assembly 14 may be used as the adsorbent coating surface. For example, the panel mounting member 52 may be used as one of the panels.

1 ion implanter, 10 cryopumps, 12 freezers, 14 cryopanel assemblies, 16 radiation shields, 22 first cooling stages, 24 second cooling stages, 30 cryopump internal open spaces, 31 cryopump openings, 32 Louver, 33 shield front, 35 open area, 50 cryopanel, 52 panel mounting member, 54 open area, 60 top panel, 62 middle panel, 64 lower panel, 76 adsorption area, 82 condensation area, 86 boundary, 100 CP controller .

Claims (19)

A freezer comprising a first cooling stage for providing a first cooling temperature, and a second cooling stage for providing a second cooling temperature lower than the first cooling temperature and used for adsorption of non-condensable gas;
A radiation shield comprising a shield front end forming an opening for receiving gas, and thermally connected to the first cooling stage and surrounding the second cooling stage;
A cryopanel assembly thermally connected to a second cooling stage, the cryopanel assembly forming an open space in the opening between the outer circumferential portion and the radiation shield and visually viewing at least a portion from the front end of the shield.
And,
The cryopanel assembly includes a top panel facing the opening, an intermediate panel including a front panel facing the opening and disposed opposite the opening with respect to the top panel, the panel front of the intermediate panel An open portion continuous to the open space is formed between an adjacent cryopanel and a front face of the panel, the open portion having a depth greater than a distance between the adjacent cryopanel and the front face of the panel,
The intermediate panel has an adsorption region for non-condensable gas on the front surface of the panel, and the adsorption region is inside a boundary defined by the line of sight from the front end of the shield to the end of the adjacent cryopanel and the front surface of the panel. Formed in
Cryopump, characterized in that. The method according to claim 1,
The adsorption area occupies an area inside the boundary on the front surface of the panel;
Cryopump, characterized in that. The method according to claim 1,
Said intermediate panel having a condensation zone for condensable gas on said surface, said condensation zone including a zone outside said boundary at the front of said panel;
Cryopump, characterized in that. The method according to claim 1,
The outer periphery of the intermediate panel extends parallel to the top panel and to a position closer to the radiation shield than the outer periphery of the top panel.
Cryopump, characterized in that. The method according to claim 1,
The cryopanel assembly further includes a lower panel disposed on the side opposite to the opening with respect to the middle panel, wherein an outer circumference of the lower panel is parallel to the middle panel and to a position closer to the radiation shield than the outer circumference of the middle panel. Stretched
Cryopump, characterized in that. The method according to claim 1,
The intermediate panel includes a plurality of plates arranged in parallel with each other, each including a front face facing the opening and a back face facing the opening.
Cryopump, characterized in that. The method according to claim 1,
And further comprising a louver thermally connected to the radiation shield and disposed in the opening, wherein the louver has an intermediate size between a top panel and an intermediate panel, and an open area is formed between an outer circumference of the louver and the radiation shield.
Cryopump, characterized in that. The method according to claim 1,
The intermediate panel has at least 70% of the surface area covered with an adsorbent, the adsorbent is hydrogen adsorbable, the cryopump has a hydrogen capture probability of at least 30%,
Wherein the adsorbent is contained in the open portion and the adsorbent visibility is less than 7%, which is the ratio of the adsorbent area visible from the opening to the total area of the adsorbent.
Cryopump, characterized in that. A plurality of cryopanel arrays having a radiation shield and a front side inwardly arranged within the radiation shield, each having a front surface facing the opening of the radiation shield and a back surface facing away from the opening; A cryopump comprising a cryopanel assembly that forms an open space in the opening between an outer circumferential portion of the cryopanel and the radiation shield,
Wherein the cryopanel assembly has at least 70% of the total area of the front and back surfaces of the plurality of cryopanels covered with a hydrogen adsorbent and the cryopump has a hydrogen capture probability of at least 30%,
The adsorbent is contained between each rear surface of the plurality of cryopanels and the front surface of the cryopanel adjacent to the inside of the cryopanel, and is viewable from the opening with respect to the total area of the adsorbents of the plurality of cryopanels. Adsorbent visibility rate which is ratio of adsorbent area is less than 7%
Cryopump, characterized in that. The method according to claim 9,
In the arrangement of the plurality of cryopanels, at least a part of the inner cryopanel is shielded from the opening by the front cryopanel,
Said adsorbent is formed in the shielded part of a cryopanel so that it cannot be seen from the said opening.
Cryopump, characterized in that. The method according to claim 9,
The total area of the adsorbent is 90% or less of the total area of the front and rear surfaces of the plurality of cryopanels.
Cryopump, characterized in that. The method according to claim 9,
At least 90% of the adsorbent being exposed to the radiation shield or the opening
Cryopump, characterized in that. An arrangement of a plurality of cryo sorption panels surrounded in the cryopump internal open space opened in the cryopump opening, and a radiation shield surrounding the cryopump internal open space,
At least one of the plurality of cryo sorption panels includes a panel end that projects into the cryopump internal open space and faces the radiation shield, the panel end having a region in which an adsorbent is missing.
Cryopump, characterized in that. The method according to claim 13,
Adsorbent missing zones formed on the same plane as adsorbent presence zones
Cryopump, characterized in that. The method according to claim 13,
Adsorbent missing zones having exposed surface of cryopanel substrate for cryo condensation
Cryopump, characterized in that. The method according to claim 13,
The adsorbent missing zone being at the periphery edge exposed area visible through the cryopump opening
Cryopump, characterized in that. Masking the substrate of the cryopanel,
Comprising adsorbing an adsorbent to the surface of the substrate that is not masked
Method for producing a cryopump, characterized in that. 18. The method of claim 17,
Masking includes masking exposed portions of the substrate that are not shielded by another cryopanel.
Method for producing a cryopump, characterized in that. 18. The method of claim 17,
For each cryopanel in the arrangement of a plurality of cryopanels, mask the outside of the boundary determined by the intersection of the gaze from the front end of the radiation shield to the end of the cryopanel adjacent to the cryopanel and the cryopanel. Further comprising determining as an area
Method for producing a cryopump, characterized in that.

Images