TW201314036A - Low temperature pump and method of manufacturing the same - Google Patents

Abstract

The invention provides a low temperature pump for carrying out high-speed venting on the noncondensable gases, such as hydrogen, etc., and a method of manufacturing the same. The low temperature pump comprises a plurality of low temperature absorbing plates (50) surrounded by a low temperature pump inner space (30) opened to a low temperature pump opening (31), and a radiation protective cover (16) surrounding the low temperature pump inner space (30). At least one of the low temperature absorbing plates (50)is protruded towards the low temperature pump inner space (30) and faces the plate tail end of the low temperature pump inner space (30), and the plate tail end possesses an adsorbent falling off area (82).

Description

Cryopump and manufacturing method thereof

The present invention relates to a cryopump and a method of manufacturing the same.

The cryopump is a vacuum pump that traps gas molecules and vents by condensation or adsorption on a cryopanel that is cooled to an ultra-low temperature. Cryopumps are generally utilized to achieve a clean vacuum environment required in semiconductor circuit manufacturing processes and the like. In one of the application processes of the cryopump, for example, an ion implantation process may have a non-condensable gas such as hydrogen occupying a large part of the gas to be exhausted. The non-condensable gas can be initially vented by adsorption in an adsorption zone cooled to an ultra-low temperature.

(previous technical literature) (Patent Literature)

Patent Document 1: Japanese Laid-Open Patent Publication No. Hei 1-92591

Patent Document 2: Japanese Laid-Open Patent Publication No. 60-13992

Patent Document 3: Japanese Patent Publication No. 2008-514849

Patent Document 4: Japanese Laid-Open Patent Publication No. 2009-162074

One of the exemplary objects of one aspect of the present invention is to provide a cryopump for performing high-speed exhaust of a non-condensable gas such as hydrogen and a method for manufacturing the same.

A cryopump according to an aspect of the present invention includes: a refrigerator including a first cooling stage for supplying a first cooling temperature and for providing adsorption of a non-condensable gas lower than the first cooling temperature; a second cooling stage using a second cooling temperature; the radiation shield including a shield front end forming an opening for receiving gas, the radiation shield being thermally connected to the first cooling stage and surrounding the second cooling stage; The heat is connected to the second cooling stage, and an open space facing the opening is formed between the outer peripheral portion and the radiation shield, and at least a portion can be confirmed from the front end of the shield. The cryopanel assembly includes a top plate and an intermediate plate, the top plate facing the opening, and the intermediate plate includes a front plate facing the opening and disposed opposite to the top plate on the opposite side of the opening, and in the plate with the intermediate plate An open portion continuous with the open space is formed between the oppositely facing cryopanel and the front of the panel, the depth of the open portion being greater than the spacing between the adjacent cryopanel and the front of the panel, wherein the intermediate panel is The front surface of the plate has an adsorption region for adsorbing a non-condensable gas, and the adsorption region is formed on the inner side of a boundary defined by the intersection of the line of sight from the front end of the radiation shield to the end of the adjacent cryopanel and the front surface of the front plate. .

A cryopump according to an aspect of the present invention includes a radiation shield and a cryopanel assembly, and the cryopanel assembly is included in the radiation shield from the front to the deep and has an opening toward the radiation shield Arranging a plurality of cryopanels on a front surface and a back surface facing the opposite side of the opening, and forming a front direction between the outer peripheral portion of the plurality of cryopanels and the radiation shield The open space of the opening. In the above cryopanel assembly, at least 70% of the total area of the front and back surfaces of the plurality of cryopanels is covered by an adsorbent capable of adsorbing hydrogen, the cryopump having a hydrogen capture probability of at least 30%, and the adsorbent is Between the back surface of each of the plurality of cryopanels and the front surface of the cryopanel adjacent to the deep portion of the cryopanel, the ratio of the adsorbent area confirmed from the opening to the total adsorbent area of the plurality of cryopanels is The visible rate of the adsorbent is less than 7%.

A cryopump according to an aspect of the present invention includes: an array of a plurality of cryosorption plates surrounded by an open space inside a cryopump opened to a cryopump opening; and a radiation shield surrounding an open space inside the cryopump. At least one of the plurality of cryosorption plates includes an end of the plate that protrudes toward the inside of the cryopump and faces the radiation shield, and the end of the plate has a region where the adsorbent falls off.

Another aspect of the invention is a method of making a cryopump. The method comprises: masking a substrate of the cryopanel; and adhering the adsorbent to a surface of the substrate that is not masked.

According to the present invention, it is possible to provide a cryopump for performing high-speed exhaust of a non-condensable gas such as hydrogen and a method for manufacturing such a cryopump.

An aspect of the present invention provides a cryopump having an exposed type of cryosorption plate. The plate is arranged at a location visible from the opening of the cryopump or In his part, there is a region where an adsorbent such as activated carbon falls off. Most of the surface of the plate and the adsorbent thereon are configured to be covered by the adjacent plates and cannot be directly confirmed from the cryopump opening, and the visibility of the adsorbent confirmed from the cryopump opening is zero or a little. The adsorbent is exposed in an open space in which the surrounding plates are arranged. The adsorbent shedding zone is formed on the surface common to the adsorbent present region, and the boundary of the adsorbent shedding zone is defined by the adsorbent. That is, the detached area of the adsorbent and the existing area are distinguished by a common plate surface.

This combined and non-exposed hybrid structure is beneficial for both high speed venting of non-condensable gases and protection of adsorbents from difficult regeneration gases. This is related to maintaining stable exhaust performance by repeating the regeneration process a plurality of times. Further, the visibility of the detachment of the adsorbent from the adsorption plate is lowered, which contributes to providing a low-temperature pump having improved exhaust efficiency and energy-saving performance of the non-condensable gas.

In a typical use of a cryopump, a condensing gas and a small amount of non-condensable gas are contained in the gas to be vented. In order to avoid the adsorption property of the non-condensable gas due to the accumulation of the ice layer of the condensable gas, the cryopump for this typical use covers the low-temperature adsorption plate or the adsorption plate by a low-temperature condensing plate or a condensing plate. A typical cryosorption panel is formed by covering the entire area of a face with activated carbon.

For example, a cryopanel structure has a dual structure having a condensing plate for capturing a condensable gas on the outside and an adsorption plate for capturing a non-condensable gas on the inner side thereof. Another cryopanel structure has a low temperature condensation surface on the surface facing the cryopump opening and a low temperature adsorption surface therein. In the case where the plate has, for example, a bent portion at its end, for example, in addition to being folded The entire area of one side of the plate other than the surface of the curved portion defined by the curve is covered with activated carbon, or the entire area of the surface including the bent portion is covered with activated carbon.

Generally, both the condensing plate and the adsorption plate are cooled to an ultra-low temperature of the same cooling temperature, for example, 10K to 20K. Condensation plates and adsorption plates are used to protect themselves from the radiation shield or radiation shield that protects itself. The radiation shield is cooled to an ultra-low temperature higher than the cooling temperature of the condensing plate and the adsorption plate, for example, 80K to 100K. The radiation shield can also be considered as a cryopanel that provides a relatively high temperature ultra-low temperature surface.

Further, depending on the use of the cryopump, condensation of the condensable gas toward the ultra-low temperature surface does not become a problem. For example, a cryopump for an ion implantation apparatus can be mentioned. In this application, the amount of gas condensed in the cryogenic plate is small, and the main purpose of the cryopump is the exhaust of a non-condensable gas such as hydrogen. Therefore, it is desirable to make the non-condensable gas easily reach by exposing the adsorption plate to the cryopump opening. Thereby, a higher exhaust speed can be achieved.

An increase in the exhaust velocity based on exposure helps to reduce the area of the adsorbent plate used to achieve a desired exhaust velocity. This is because the fluidity of the gas to the adsorbent becomes good by exposure, and the exhaust velocity of the average unit area of the sheet becomes high. As a result, the required board area is reduced, and the weight of the cryopanel structure is also reduced.

The reduction in the weight of the plate shortens the time required for the cryogenic pump regeneration process. Since the cryopump is a so-called trap type vacuum pump, the regeneration process of discharging the gas accumulated inside is performed to the outside at an appropriate frequency. Regeneration means lower The temperature of the warm plate is raised to a temperature higher than the operating temperature of the cryopanel (for example, normal temperature), and the gas which is condensed or adsorbed on the surface of the plate is discharged and discharged to the outside, and is cooled again to the operating temperature of the cryopanel. One important factor in determining the regeneration time is the time required for re-cooling. The re-cooling time is related to the weight of the panel structure. According to the decrease in the weight of the plate structure, the re-cooling time is shortened, and as a result, the regeneration time is also shortened.

The gas accumulated in the cryopump is generally substantially completely discharged by the regeneration process, and when the regeneration is completed, the cryopump is restored to the standard exhaust performance. However, a part of the accumulated gas is relatively high in the proportion of the adsorbent remaining in the adsorbent.

For example, in a cryopump installed as a vacuum evacuation device for an ion implantation device, it has been confirmed that an adhesive substance adheres to activated carbon as an adsorbent. The adhesive substance is difficult to completely remove even after being regenerated. The adhesive substance is caused by an organic off-gas discharged from the photoresist coated on the substrate to be processed. Or there may be a toxic gas which is caused by a source gas as a dopant gas in the ion implantation process. There may be other by-product gases that can be caused by the ion implantation process. It is also possible that these gases are combined to form an adhesive substance.

In the ion implantation process, most of the gas that the cryopump performs exhausting may be hydrogen gas. The hydrogen gas is substantially completely discharged to the outside by regeneration. If it is difficult to regenerate the gas, the effect of the hard-to-regenerate gas on the exhaust performance of the cryopump is slight in the primary cryopump treatment. However, during the process of repeatedly performing the cryopump treatment and the regeneration treatment, there is a possibility that the regenerative gas is gradually accumulated in the adsorbent and the exhaust performance is lowered. When When the gas performance is below the allowable range, for example, it is necessary to replace the adsorbent or replace the cryopanel at the same time, or perform maintenance work including chemically difficult regeneration gas removal treatment of the adsorbent.

Therefore, the cryopump according to an aspect of the present invention is provided with an exposed type of low-temperature adsorption plate, and a part of the adsorbent such as activated carbon is detached from a part thereof. The exposed cryosorption plate array has an open space inside the cryopump that is open to the cryopump opening. The internal open space is surrounded by a radiation shield. The open partial space is defined by mutually adjacent adsorption plates in the arrangement of the cryosorption plates, which are open to the outer space of the cryopump through the open space inside the cryopump. The openness of the cryogenic adsorption plate promotes gas reaching the surface of the plate and assists in achieving high-speed exhaust of a non-condensable gas such as hydrogen based on a cryopump.

In one embodiment, the detached portion of the adsorbent is set in a region of the cryosorption plate that is confirmed from the outside of the cryopump through the cryopump opening. The sorbent detachment portion may also be provided at the end of the adsorption plate which protrudes toward the inside of the cryopump and faces the radiation shield. The shedding site can be used as a low temperature condensing plate.

Thus, by avoiding the direct exposure of the adsorbent to the cryopump opening or making the visibility of the adsorbent from the cryopump opening extremely small, the effect of the difficult regeneration gas contained in the gas entering the cryopump on the adsorbent can be prevented or reduced. The hardly regenerated gas accumulates in the condensing plate, so that the accumulation of the adhesive substance to the adsorbent is lowered. In this way, it is possible to achieve both high-speed exhaust of the non-condensable gas and protection of the adsorbent from the difficult-to-regenerate gas.

A cryopump of a specific example of the technical idea is suitable for ion implantation The cryopump used in the vacuum exhaust system. Further, another example is a cryopump suitable for use in a vacuum exhaust system of a substrate processing apparatus. The substrate processing apparatus is a substrate covered with a photoresist, for example, by a program gas.

Here, the hard-to-renew gas is, for example, in a predetermined regeneration process, the gas discharged to the outside of the pump is not completed at the time when the discharge of the predetermined gas (for example, hydrogen) to the outside of the cryopump is substantially completed. Further, even if it is adjusted so that the residual gas in the adsorbent after the predetermined gas is substantially completely discharged to the outside of the cryopump exceeds the reference gas, it is called a hardly regenerated gas. For example, an organic outgas from a photoresist or other coating applied to the surface of the wafer may also have a higher ratio of residual to the adsorbent during the regeneration treatment. Further, the toxic dopant gas used in the ion implantation treatment may also become a difficult-to-regenerate gas.

The photoresist is, for example, an organic photoresist composed of an organic material. The program gas may also be a reactive process gas that directly chemically reacts with a photoresist to be treated (for example, a substrate) or a surface thereof. Alternatively, the program gas may be a gas for assisting in introducing a reactive gas into the object to be treated. In the case where the substrate processing apparatus is a sputtering apparatus, the program gas is an inert gas such as argon. In the case where the substrate processing apparatus is an ion implantation apparatus, the program gas is, for example, a hydrogen gas or a dopant gas. The organic gas can be evolved from the photoresist by the interaction of the program gas and the photoresist in the program. Moreover, even if it is not in the program, it is possible to release outgassing from the photoresist by a vacuum environment. The organic gas may include, for example, an aromatic, a linear hydrocarbon, an alcohol, a ketone, an ether, or the like.

The hardly regenerated gas is not limited to the organic gas derived from the photoresist described above, the dopant gas used in the ion implantation treatment, or the like. For example, depending on the program, it is possible that the program gas itself is difficult to regenerate. Further, there is a case where the evolved gas from the paint other than the photoresist coated on the substrate is a hardly regenerated gas.

The cryopump according to the embodiment may further include: a refrigerator including a first cooling stage for supplying a first cooling temperature; and for supplying the non-condensable gas below the first cooling temperature a second cooling stage of the second cooling temperature; the radiation shield includes a shield front end that forms an opening for receiving the gas, the radiation shield is thermally connected to the first cooling stage and surrounds the second cooling stage; and the cryopanel assembly The heat is connected to the second cooling stage, and an open space facing the opening is formed between the outer peripheral portion and the radiation shield, and at least a part of the shield can be confirmed from the front end of the shield.

The cryopanel assembly may also include a top panel facing the shroud opening, the intermediate panel facing the shroud opening facing the shroud opening, and disposed on the opposite side of the shroud opening relative to the top panel. An open portion continuous to the open space may be formed between the cryopanel adjacent to the front surface of the intermediate plate and the front of the panel. The depth of the open portion may be greater than the spacing of the adjacent cryopanel and the front of the panel.

The intermediate plate may also have an adsorption region for non-condensable gas in front of the plate. The adsorption region may be formed on the inner side of the boundary defined by the intersection of the line of sight from the tip end of the shield to the end of the adjacent cryopanel and the front surface of the panel. The adsorption region may also occupy a region inside the aforementioned boundary in front of the aforementioned plate.

The intermediate plate may also have a condensation zone for condensing gas on its surface. The condensed area may also include an area outside the aforementioned boundary in the front surface of the aforementioned plate.

The outer peripheral portion of the intermediate plate may also be parallel to the top plate and extend to a position closer to the radiation shield than the outer peripheral portion of the top plate. The intermediate plate may further include a plurality of thin plates each including a front surface facing the front surface of the shroud opening and an opposite side facing the opening and arranged in parallel with each other.

The cryopanel assembly may also include a side panel disposed opposite the opposite side of the shroud opening relative to the intermediate panel. The outer peripheral portion of the lower side plate may extend parallel to the intermediate plate and extend closer to the radiation shield than the outer peripheral portion of the intermediate plate.

The cryopump may also have a louver that is thermally coupled to the radiation shield and that is disposed in the shroud opening. The louver has an intermediate size between the top plate and the intermediate plate, and an open area may be formed between the outer peripheral portion of the louver and the radiation shield.

At least 70% of the surface area of the intermediate plate is covered by the adsorbent, which adsorbs hydrogen, and the cryopump can also have a hydrogen capture probability of at least 30%. The adsorbent is also contained in the open portion, and the ratio of the area of the adsorbent confirmed from the opening of the shield to the total area of the adsorbent, that is, the visibility of the adsorbent is less than 7%.

The cryopump according to the embodiment may further include a radiation shield and a cryopanel assembly, wherein the cryopanel assembly includes an arrangement of a plurality of cryopanels arranged in the radiation shield from the front to the deep, and Each has a front surface facing the opening of the radiation shield and a back surface facing the opposite side of the opening, and is formed between the outer peripheral portion of the plurality of cryopanels and the radiation shield There is an open space facing the aforementioned opening. In the cryopanel assembly, at least 70% of the total area of the front and back of the plurality of cryopanels may also be covered by an adsorbent capable of adsorbing hydrogen, and the cryopump has a hydrogen capture probability of at least 30%. The adsorbent may be contained between the back surface of each of the plurality of cryopanels and the front surface of the cryopanel adjacent to the deep portion of the cryopanel, and the adsorbent area confirmed from the shroud opening may be adsorbed relative to the plurality of cryopanels. The ratio of the total area of the agent, that is, the visible rate of the adsorbent, is less than 7%.

In the arrangement of the plurality of cryopanels, at least a portion of the deep cryopanel is blocked relative to the opening due to the cryopanel directly in front, and the adsorbent is disposed at the blocking portion of the cryopanel so as not to be confirmed from the shroud opening.

The total area of the adsorbent may also be less than 90% of the total area of the front and back of the plurality of cryopanels.

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

The cryopump according to the embodiment may further include: an array of a plurality of cryosorption plates surrounded by an open space inside the cryopump opened to the cryopump opening; and a radiation shield surrounding the open space inside the cryopump. At least one of the plurality of cryosorption plates may also include an end of the plate that protrudes toward the interior of the cryopump and faces the radiation shield, and the end of the plate has a region where the adsorbent falls off.

The adsorbent detachment region may also be formed on a surface common to the region where the adsorbent is present. The adsorbent detachment region may also expose the surface of the cryopanel substrate for low temperature condensation. The adsorbent detachment region may also be located at a peripheral exposed portion confirmed by the cryopump opening.

A method of manufacturing a cryopump according to an embodiment may include masking a substrate of the cryopanel and adhering the adsorbent to a surface of the substrate that is not masked. Performing the mask may also include masking the exposed portions of the substrate that are not blocked by other cryopanels. The method may further comprise: a boundary defined by the intersection of the line of sight from the front end of the radiation shield to the end of the cryopanel adjacent to the cryopanel and the cryopanel for each cryopanel of the arrangement of the plurality of cryopanels The outer side is determined as the mask area.

The cryopump according to the embodiment may further include: a refrigerator including a first cooling stage for supplying a first cooling temperature; and for supplying the non-condensable gas below the first cooling temperature a second cooling stage of the second cooling temperature; the radiation shield includes a shield front end formed with an opening for receiving the gas, the radiation shield being thermally connected to the first cooling stage and surrounding the second cooling stage; and the cryopanel assembly The heat is connected to the second cooling stage, and an open space facing the opening of the shroud is formed between the outer circumference and the radiation shield, and at least a part of the shroud front end can be confirmed.

The cryopanel assembly may also include a top panel facing the shroud opening, and the top panel including the front side of the panel facing the shroud opening and disposed opposite the shroud opening on the opposite side. An outer peripheral portion of the cryopanel adjacent to the front surface of the intermediate plate and a portion facing the front surface of the outer peripheral portion may extend parallel to the radiation shield in the open space, and the front of the panel is divided into non-condensing The adsorption zone for the gas and the condensation zone for the condensable gas. The outer peripheral portion of the front surface of the plate may be divided into an adsorption region for a non-condensable gas and a condensation region for a condensable gas.

The adjacent cryogenic plate may also be a top plate, and the outer peripheral portion of the intermediate plate is extended Extends to a position closer to the radiation shield than the outer peripheral portion of the top plate. Each of the top plate and the intermediate plate may also include a plurality of thin plates each including a front surface facing the front opening of the shroud and facing the opposite side of the opening and arranged in parallel with each other, and the thin plate of the intermediate plate is larger than the thin plate of the top plate.

The cryopanel assembly may further comprise a side panel disposed opposite the opposite side of the shroud opening relative to the intermediate panel. The outer peripheral portion of the lower side plate may extend parallel to the intermediate plate and extend closer to the radiation shield than the outer peripheral portion of the intermediate plate. The lower side panel may also include a plurality of thin plates each including a front surface facing the front of the shroud opening and a rear side facing the opposite side of the opening and arranged in parallel with each other, the thin plate being larger than the thin plate of the intermediate plate.

An open portion continuous to the open space may be formed between the aforementioned portion of the front surface of the front plate of the intermediate plate and the outer peripheral portion of the adjacent low temperature plate, the open portion having a depth greater than the adjacent cryopanel and the front of the plate Interval.

The cryopump may also have a louver that is thermally coupled to the radiation shield and that is disposed in the shroud opening. The louver may have an intermediate size of the top plate and the intermediate plate, and an open area is formed between the outer peripheral portion of the louver and the radiation shield.

The cryopump may also have a hydrogen capture probability of at least 30%, the intermediate plate comprising a cryopanel substrate for supporting the adsorbent capable of adsorbing hydrogen on the surface, by up to 30% of the total surface area of the cryopanel substrate The adsorbent is detached and the ratio of the hydrogen gas venting speed of the cryopump to the sorbent area, that is, the hydrogen gas venting efficiency, is increased as compared with the case where the entire surface of the cryopanel substrate is covered by the adsorbent.

The cryopump of an embodiment may also be a cryogenic pump as follows: The hood and the cryopanel assembly, the cryopanel assembly includes a plurality of cryopanels arranged in the radial shield from the front to the deep, and between the outer peripheral portion of the plurality of cryopanels and the radiation shield Formed with an open space facing the shroud opening, the cryopump having a hydrogen capture probability of at least 30%. The plurality of cryopanels may further comprise a cryopanel substrate for supporting the adsorbent capable of adsorbing hydrogen on the surface, wherein the adsorbent is detached from the total surface area of the cryopanel substrate by up to 30%, and the adsorbent is removed from the adsorbent Compared with the case of covering the entire surface of the cryopanel substrate, the ratio of the hydrogen gas discharge velocity to the adsorbent area of the cryopump is increased, that is, the hydrogen gas exhaust efficiency.

The hydrogen exhaust efficiency may also be 5 × 10 ^-2 L / s ‧ mm ² or more. At least 10% of the total surface area of the cryopanel substrate may also be the adsorbent shedding zone. At least 90% of the adsorbent may also be exposed to the radiation shield or shroud opening.

The method of one embodiment may further include: determining a plate structural parameter value that gives a maximum hydrogen exhaust velocity when changing a structural parameter of the plate under a condition that the adsorbent is detached from a portion of the surface of the cryosorption plate; and according to the plate The structural parameter values determine the structure of the cryosorption plate array. The plate structure parameters may also include the dimensions of the cryosorption plates.

Fig. 1 is a view schematically showing an ion implantation apparatus 1 and a cryopump 10 according to an embodiment of the present invention. The ion implantation apparatus 1 as an example of a beam irradiation device for irradiating a beam to a target includes an ion source unit 2, a mass analyzer 3, a beam tube unit 4, and an end station unit 5.

The ion source unit 2 is configured to ionize an element to be implanted on the surface of the substrate and to extract it as an ion beam. The mass analyzer 3 is configured to be disposed downstream of the ion source unit 2 and to select ions required from the ion beam.

The beam tube portion 4 is provided downstream of the mass analyzer 3 and includes a lens system for shaping the ion beam and a scanning system for scanning the ion beam with the substrate. The end station unit 5 is provided downstream of the beam tube unit 4, and includes a substrate holder (not shown) that serves as an object to be irradiated, that is, a substrate holder 8 that serves as an irradiation target, and a drive for the ion beam drive substrate 8. System and so on. The beam path 9 in the beam tube portion 4 and the end station portion 5 is schematically indicated by a dotted arrow.

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

For example, the cryopumps 10a and 10b are used for vacuum evacuation of the vacuum chamber of the beam tube portion 4, and are attached to the cryopump mounting opening of the wall surface of the vacuum chamber of the beam tube portion 4. The cryopump 10c is attached to the cryopump mounting opening of the vacuum chamber wall surface of the end station portion 5 as vacuum chamber for the vacuum chamber of the end station portion 5. Further, the vacuum exhaust system 6 may be configured such that the beam tube portion 4 and the end station portion 5 are exhausted by one cryopump 10, respectively. Further, the vacuum exhaust system 6 may be configured such that the beam tube portion 4 and the end station portion 5 are exhausted by a plurality of cryopumps 10, respectively.

The cryopumps 10a and 10b are attached to the beam tube portion 4 through the gate valves 7a and 7b, respectively. The cryopump 10c is attached to the end station portion 5 through the gate valve 7c. Further, the cryopumps 10a, 10b, and 10c are collectively referred to as a cryopump 10 as appropriate, and the gate valves 7a, 7b, and 7c are collectively referred to as a gate valve 7. When the ion implantation apparatus 1 is operated, the gate valve 7 is opened and the exhaust based on the cryopump 10 is exhausted. When regenerating At the time of the cryopump 10, the gate valve 7 is closed.

Further, the vacuum exhaust system 6 may further include a turbo molecular pump and a dry vacuum pump for setting the ion source unit 2 to a high vacuum. Further, the vacuum exhaust system 6 may be provided with a rough pump for venting the beam tube portion 4 and the end station portion 5 from the atmospheric pressure to the operation of the cryopump 10 in parallel with the cryopump 10.

The gas existing in the beam tube portion 4 and the end station portion 5 and the introduced gas are exhausted by the cryopump 10. Most of the exhausted gas is usually hydrogen gas. The exhaust gas containing hydrogen gas is exhausted from the beam path 9 using the cryopanel of the cryopump 10. Further, the exhaust gas may contain a gas released from a photoresist applied to the substrate, a dopant gas, or a by-product gas in the ion implantation process.

The ion implantation apparatus 1 is provided with a main controller 11 for controlling the apparatus. Further, in the cryopump 10, a cryopump controller (hereinafter simply referred to as "CP controller" for short) 10 for controlling the cryopump 10 is provided. The main controller 11 may also be referred to as an upper controller of the cryopump 10 through the CP controller 100. Each of the main controller 11 and the CP controller 100 includes a CPU that executes various arithmetic processing, a ROM that stores various control programs, a RAM that is used as a work area for storing data or executing programs, an input/output interface, and a memory. The main controller 11 and the CP controller 100 are connected to be in communication with each other.

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

As described above, the cryopump 10 for the ion implantation apparatus 1 mainly discharges hydrogen gas. In order to increase the productivity of the ion implantation process of the ion implantation apparatus 1, a cryopump 10 capable of rapidly exhausting hydrogen gas is required. Further, a cryopump having an improved exhaust gas efficiency and an excellent energy saving property is required. Therefore, the cryopump 10 includes an adsorption region for forming a non-condensable gas that is substantially non-exposed in the exposed low-temperature adsorption plate array 14.

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

The exposed cryopanel array 14 is formed with a cryopump internal open space 30 that is open to the cryopump opening 31 between the outer peripheral portion and the radiation shield 16. The open partial space 54 is defined by mutually adjacent cryopanels 50 of the cryopanel array 14 which is continuous to the cryopump internal open space 30. The adsorption region is formed on the surface of the cryopanel 50 surrounding the partial space 54. The openness of such a local space 54 promotes gas reaching the adsorption zone, assisting in achieving high velocity exhaust of a non-condensable gas such as hydrogen based on the cryopump 10.

At least a portion of the open partial space 54 is blocked from the cryopump opening 31 by the adjacent cryopanel 50, and the adsorption region is received in the partial space 54. By avoiding the adsorption area directly exposing to the cryopump opening 31, The hard-to-regenerate gas contained in the gas entering the cryopump 10 protects the adsorption zone. In this way, it is possible to achieve both high-speed exhaust gas of the non-condensable gas and protection of the adsorption region from the difficult-to-regenerate gas.

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 a first cooling temperature level. The first cryopanel captures a gas having a low vapor pressure by condensation at a first cooling temperature level. For example, a gas having a vapor pressure lower than the reference vapor pressure (for example, 10 ^-8 Pa) is exhausted.

Since the second cryopanel is an adsorption plate, since the vapor pressure is high, the non-condensable gas which is not condensed even at the second cooling temperature level is captured by adsorption. For this purpose, the entire area of the surface of the plate or mostly is the adsorption area. The adsorption zone is formed, for example, by providing an adsorbent on the surface of the plate. The adsorbent is, for example, activated carbon. The adsorption region may be an adsorbent such as zeolite formed to selectively adsorb a specific gas molecule, or may be a porous surface layer thus formed on a plate substrate. The non-condensable gas is adsorbed to the adsorption region cooled to the second cooling temperature level and is exhausted. The non-condensable gas contains hydrogen. When the gas having a low vapor pressure is present in the atmosphere at the second cooling temperature level, it is trapped on the adsorbent of the adsorption plate or on the surface without the adsorbent by condensation.

The cryopump 10 is provided with a refrigerator 12 . The refrigerator 12 generates cold by a heat cycle in which an actuating gas is sucked in, and is internally expanded and discharged. The refrigerator 12 is a Gifford-McMahon type freezer (so-called GM refrigerator). Further, the refrigerator 12 is a two-stage refrigerator having a first stage cylinder 18, a second stage cylinder 20, a first cooling stage 22, a second cooling stage 24, and a cold. Freezer motor 26. 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) are connected to each other. A cool storage material is incorporated in the first stage displacer and the second stage displacer. Further, the refrigerator 12 may be a refrigerator other than the two-stage GM refrigerator. For example, a single-stage GM refrigerator may be used, or a pulse tube refrigerator or a Solvay refrigerator may be used.

The refrigerator 12 includes a flow path switching mechanism that periodically switches the flow path of the operating gas in order to periodically perform the suction and discharge of the operating gas. The flow path switching mechanism includes, for example, a valve portion and a drive portion that drives the valve portion. The valve portion is, for example, a rotary valve, and the drive portion is a motor for rotating the rotary valve. The motor can be, for example, an AC motor or a DC motor. Further, the flow path switching mechanism may be a direct-acting mechanism driven by a linear motor.

A refrigerator motor 26 is provided at one end of the first stage cylinder 18. The refrigerator motor 26 is provided inside the motor casing 27 formed at the end of the first stage cylinder 18. The refrigerator motor 26 is connected to the first stage displacer and the second stage so that the first stage displacer and the second stage displacer can reciprocate inside the first stage cylinder 18 and the second stage cylinder 20, respectively. Displacer. Further, the refrigerator motor 26 is connected to the valve so that a movable valve (not shown) provided inside the motor casing 27 can be rotated forward and backward.

The first cooling stage 22 is an end portion of the first stage cylinder 18 that is disposed on the second stage cylinder 20 side, that is, a connection portion between the first stage cylinder 18 and the second stage cylinder 20. Further, 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 respectively soldered, for example, by brazing It is fixed to the first stage cylinder 18 and the second stage cylinder 20.

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

Specifically, first, the high pressure operating gas is supplied from the compressor 102 to the refrigerator 12. At this time, the refrigerator motor 26 drives the movable valve inside the motor casing 27 to a state in which the gas supply port 42 and the internal space of the refrigerator 12 are communicated. When the internal space of the refrigerator 12 is filled with the high pressure operating gas, the refrigerator motor 26 switches the movable valve to communicate the internal space of the refrigerator 12 with the gas discharge port 44. Thereby, the actuating gas expands and is recovered to the compressor 102. The first stage displacer and the second stage displacer reciprocate inside the first stage cylinder 18 and the second stage cylinder 20 in synchronization with the movement of the movable valve. By repeating such a thermal cycle, the refrigerator 12 generates cold on the first cooling stage 22 and the second cooling stage 24.

The second cooling stage 24 is cooled to a temperature lower than that of the first cooling stage 22. The second cooling stage 24 is cooled to, for example, about 10K to 20K, and the first cooling stage 22 is cooled to, for example, about 80K to 100K. A first temperature sensor 23 for measuring the temperature of the first cooling stage 22 is attached to the first cooling stage 22, and a second temperature for measuring the temperature of the second cooling stage 24 is attached to the second cooling stage 24. Temperature sensor 25.

Solidified on the first cooling stage 22 of the refrigerator 12 in a state of being thermally connected The radiation shield 16 is fixed, and the cryopanel assembly 14 is fixed to the second cooling stage 24 of the refrigerator 12 in a state of being thermally connected. Therefore, 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 (refer to 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) attached to the refrigerator motor 26. The inverter of the refrigerator motor adjusts the rated voltage and the constant frequency power supplied from an external power source such as a commercial power source to the refrigerator motor 26 by an instruction 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 supplies an operation command to the refrigerator 12 such 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 thermal cycle frequency of the refrigerator 12 is determined in accordance with the operating frequency of the refrigerator motor 26. The target temperature of the first cryopanel is determined, for example, by a procedure performed in the vacuum chamber 80 as a standard. At this time, the second cooling stage 24 and the low temperature plate assembly 14 of the refrigerator 12 are cooled to a predetermined temperature by the specification 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 for increasing the refrigerator motor 26 The frequency of operation. In conjunction with an increase in the operating frequency of the motor, the frequency of the thermal cycle in the refrigerator 12 also increases, and the first cooling stage 22 of the refrigerator 12 cools toward the target temperature. On the other hand, 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 toward the target temperature.

Usually, the target temperature of the first cooling stage 22 is set to a constant value. Therefore, when the heat load applied to the cryopump 10 is increased, the CP controller 100 outputs a command value for increasing the operating frequency of the refrigerator motor 26, and when the heat load applied to the cryopump 10 is reduced, the command value is output. Used to reduce the operating frequency of the refrigerator motor 26. Further, the target temperature may be appropriately changed. For example, the target temperature of the cryopanel may be sequentially set so as to reach the target atmospheric pressure in the exhaust target volume (for example, the vacuum chamber 80). Further, the CP controller 100 can also control the operating frequency of the refrigerator motor 26 so that the substantial temperature of the second cryopanel matches the target temperature.

In a typical cryopump, the frequency of the thermal cycle is always constant. It is set to operate at a relatively large frequency so as to be rapidly cooled from a normal temperature to a pump operating temperature, and when the heat load from the outside is small, the temperature of the cryopanel is adjusted by heating with a heater. Thereby, the power consumption becomes large. On the other hand, in the present embodiment, since the heat cycle frequency is controlled in accordance with the heat load applied to the cryopump 10, the cryopump excellent in energy saving can be obtained. Also, there is no need to set a heater, which helps to reduce power consumption.

The cryopump 10 is provided with a cryopanel assembly 14 or a cryopanel structure. The cryopanel assembly 14 is included in the second cooling stage 24 of the refrigerator 12 A plurality of cryopanels that are cooled. These plates are arranged in the radiation shield 16 from the front side, that is, the opening side to the deep side. Each cryopanel has a front side facing the shroud opening 31 and an opposite side facing the shroud opening 31, that is, the back side of the occluding portion 28. The cryopanel assembly 14 may also include a cryopanel facing the side of the radiation shield 16 or a cryopanel (not shown) oriented in other directions. On the surface of the plate, an ultra-low temperature surface for trapping gas and venting by condensation or adsorption is formed. On the surface of the cryopanel, an adsorbent such as activated carbon for adsorbing a gas is generally provided.

The cryopanel assembly 14 is formed with an internal space 30 that is open to the shroud opening 31 between the outer peripheral portion and the radiation shield 16. The cryopanel assembly 14 can identify at least a portion thereof, such as the outer perimeter, from the shroud front end 33. The cryopump 10 as shown in Fig. 2 and the cryopump 10 shown in Figs. 3 and 4 differ in the specific form of the cryopanel assembly 14. A detailed description of the structure of each of the cryopanel assemblies 14 will be described later.

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

On the other hand, on the opposite side of the shroud opening 31 of the radiation shield 16, that is, the other end on the pump bottom side, a closing portion 28 is formed. The closing portion 28 is formed by a flange portion extending toward the radially inner side at the pump bottom side end portion of the cylindrical side surface of the radiation shield 16. The cryopump 10 as shown in Fig. 2 is Since the vertical cryopump is used, the flange portion is attached to the first cooling stage 22 of the refrigerator 12. The refrigerator 12 protrudes in the inner space 30 along the center axis of the radiation shield 16, and the second cooling stage 24 is inserted into the internal space 30.

The horizontal cryopump shown in FIG. 4 is inserted and disposed in a direction intersecting the axial direction of the radiation shield 16 (generally in the orthogonal direction, in FIG. 4, from the deep side of the paper surface toward the front) The second cooling stage 24 of the refrigerator. In the case of a horizontal type, the occlusion portion 28 is generally completely occluded. The refrigerator 12 is disposed so as to protrude from the refrigerator mounting opening formed on the side surface of the radiation shield 16 toward the internal space 30 in a direction orthogonal to the central axis of the radiation shield 16 . The first cooling stage 22 of the refrigerator 12 is a refrigerator mounting opening attached to 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 attached to the second cooling stage 24. Thus, the cryopanel assembly 14 is disposed in the interior space 30 of the radiation shield 16.

Further, as shown in FIGS. 2 to 4, a baffle or louver 32 thermally connected to the radiation shield 16 is provided on the shroud opening 31 of the radiation shield 16. The louver 32 and the radiation shield 16 are disposed coaxially, and an annular open region 35 is formed between the outer peripheral portion of the louver 32 and the radiation shield 16. The louver 32 is provided at a distance from the cryopanel assembly 14 in the central axis direction of the radiation shield 16. Further, between the louver 32 and the vacuum chamber 80, a gate valve 7 is provided (refer to Fig. 1).

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

The louver 32 is formed by a plurality of louvers 38, and each louver 38 is formed in a shape of a side surface of a truncated cone having different diameters, and is arranged in a concentric shape. In the third drawing, the gap is formed between the louvers 38. However, the louvers 38 may be densely arranged such that the adjacent louvers 38 overlap each other and there is no gap when it is confirmed from above. Each louver 38 is attached to a cross-shaped support member 39 that is mounted to the mounting structure 37. The louver 32 may be formed, for example, in a concentric shape when confirmed from the side of the vacuum chamber 80, or may be formed in another shape such as a lattice shape.

The area of the open region 35 is set such that the hydrogen gas discharge speed based on the cryopump 10 reaches the required specification. Specifically, for example, the area of the open region 35 can be adjusted by changing the number of the louvers 38 of the louver 32 to make the diameter of the louver 32 different. The exposed portion of the cryopanel assembly 14 that is not blocked by the louver 32 is, for example, the peripheral portion, through the open region 35.

The cryopump 10 is mounted to the vacuum chamber 80 by a pump casing 34. The vacuum chamber 80 is, for example, a vacuum chamber of the beam tube portion 4 or the end station portion 5 (refer to Fig. 1). The cryopump 10 is an airtight space that is airtightly fixed to the vacuum chamber 80 via the flange portion 36 of the pump casing 34, and forms an airtight space that is integrated with the internal space of the vacuum chamber 80.

The pump casing 34 houses a radiation shield 16, a louver 32, and a cryopanel assembly. 14 and the first cooling stage 22 and the second cooling stage 24 of the refrigerator 12. Both the pump casing 34 and the radiation shield 16 are formed in a cylindrical shape and disposed coaxially. Since the inner diameter of the pump casing 34 is slightly larger than the outer diameter of the radiation shield 16, the radiation shield 16 is disposed between the inner surface of the pump casing 34 and at a plurality of intervals.

The pump casing 34 is formed by connecting two cylinders having different diameters in series. The large diameter cylindrical side end portion of the pump casing 34 is opened, and extends outward in the radial direction to form a connecting flange portion 36 that is connected to the vacuum chamber 80. Thus, the large diameter end of the pump casing 34 defines a cryopump opening 31 for receiving gas from the outside of the cryopump, such as the vacuum chamber 80. The small-diameter cylindrical side end portion of the pump casing 34 is fixed to the motor casing 27 of the refrigerator 12 .

The cryopanel assembly 14 is disposed in the internal space 30 of the radiation shield 16. The cryopanel assembly 14 is provided with a plurality of cryopanels 50 and a plate mounting member 52. The cryopanel assembly 14 comprises a combination of profiled or reduced diameter cryopanels.

The board mounting member 52 is configured to fixedly arrange a plurality of cryopanels 50 according to a designed board layout, and constitutes a heat transfer path from the second cooling stage 24 of the refrigerator 12 to each of the cryopanels 50. The plate mounting member 52 is, for example, a member having a bottom surface for mounting to the second cooling stage 24 and a side surface for fixing the plurality of cryopanels 50. The plate mounting member 52 has a bottom surface that faces the pump opening side and a side surface that surrounds the second cooling stage 24.

A plurality of cryopanels 50 are arranged from the front side of the shroud opening 31 toward the deep side. Each of the cryopanels 50 extends parallel to each other toward the side of the radiation shield 16. The cryopanel 50 is arranged such that the intervals of the adjacent cryopanels are equal and equally arranged. The plurality of cryopanels 50 includes a plurality of large cryopanels and a plurality of small cryopanels. An embodiment as shown in Figures 3 and 4 It contains a larger number of cryopanels. Small cryogenic panels have the shape of a shape classified as a large cryopanel. The outer peripheral end of the cryopanel protrudes from the center axis of the shroud toward the open space 30 in the radial direction. Between the outer peripheral end of the cryopanel and the side of the radiation shield 16, the open space 30 is expanded, which is an open region 35 that is directly continuous to the periphery of the louver 32.

Hereinafter, there is a case where the low temperature plate facing the cryopump opening 31 is referred to as a top plate. That is, the cryopanel closest to the cryopump opening 31 is the top plate. In Fig. 2, the top plate is a large cryopanel, but as shown in Fig. 4, the top plate is a small cryopanel. Moreover, the top plate may be a single cryopanel or a general term for a plurality of cryopanels closest to the cryopump opening 31.

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

On the other hand, in the preferred embodiment shown in FIGS. 3 and 4, the plurality of cryopanels 50 of the cryopanel assembly 14 are divided into a plurality of groups according to their sizes, the group being from the radiation shield 16 Arranged in front of the front.

In the present embodiment, the first to third groups are sequentially divided from one side close to the shroud opening 31, and the group closer to the deep portion is larger. Therefore, in the following, the first group of cryopanels is appropriately referred to as a top plate or a small cryopanel 60, and the second group of cryopanels is appropriately referred to as an intermediate plate or a medium-sized cryopanel 62, and the third group of low-temperature plates is appropriately referred to as a lower side plate or a large low temperature plate. 64. In addition, in this real In the example, the group is divided into three groups. However, the cryopanel assembly 14 may have two groups, and may have more than three groups.

Each set comprises at least one cryopanel, and each set comprises a plurality of cryopanels preferably. In one embodiment, each set has from 2 to 5 sheets of cryogenic adsorption sheets, and the cryopanel assembly 14 has a total of 8 to 14 sheets of cryogenic adsorption sheets. In Fig. 4, the small cryopanel 60, the medium-sized cryopanel 62, and the large cryopanel 64 are three, four, and three, respectively.

The medium-sized cryopanel 62 is disposed on the opposite side of the shroud opening 31 with respect to the small-sized cryopanel 60. The large cryopanel 64 is disposed on the opposite side of the shroud opening 31 with respect to the intermediate cryopanel 62. The outer peripheral portion of the intermediate low temperature plate 62 is parallel to the small cryopanel 60 and extends to a position closer to the radiation shield 16 than the outer peripheral portion of the small cryopanel 60. The outer peripheral portion of the large cryopanel 64 is parallel to the intermediate low temperature plate 62 and extends to a position closer to the radiation shield 16 than the outer peripheral portion of the intermediate low temperature plate 62. As shown in Fig. 3, the louver 32 may have an intermediate size of the small cryopanel 60 (shown by a broken line in Fig. 3) and the intermediate cryopanel 62.

In one embodiment, each cryopanel 50 has a disk shape. In this case, the plurality of cryopanels 50 comprise a large diameter disk plate, a small diameter disk plate, and an intermediate diameter disk plate. The louver 32 may also be a disc-shaped louver having an intermediate diameter disk plate and a small diameter disk plate. In the embodiment shown in Fig. 2, the louver 32 may also be a disc-shaped louver having an intermediate diameter of a large-diameter disk plate and a small-diameter disk plate.

The plurality of cryosorption panels 50 respectively include a front surface facing the shroud opening 31 or the louver 32 and facing the opposite side thereof, that is, the back surface of the occluding portion 28. For example, a thin metal plate. Adsorption regions are formed on the surface of the sheet followed by activated carbon. For example, at least 50% of the total area of the front and back faces is the adsorption zone, and the remaining 50% is the non-adsorption zone. The non-adsorption region is a region where the metal surface of the thin plate not provided with the adsorbent is exposed, and the adsorbent is detached. This adsorbent shedding zone functions as a condensation zone.

The entire area of the back surface of each of the cryopanels 50 may be an adsorption region, and at least a portion of the front surface of the cryopanel 50 may be an adsorption region. In the uppermost cryopanel, it is also possible to have an adsorption region only on the back surface. In an embodiment as shown in FIG. 2, for example, at least the central portion of the front surface of the cryopanel 50 below the uppermost cryopanel is an adsorption region, and the outer side is a non-adsorption region. Or condensation area. The entire area of the front face of these lower cryopanel 50 small and medium sized cryopanels may be an adsorption zone. The entire area in front of a number of large cryopanels located at the bottom may also be an adsorption zone.

The boundary between the adsorption zone and the non-adsorption zone, in other words, the boundary of the detachment zone and the presence zone of the adsorbent, can also be determined by the trajectory of the line of sight projected to the front of the cryopanel. This line of sight is a straight line drawn from the front end 33 of the shroud to the outer peripheral end of the cryopanel immediately before it. That is, the line of intersection of the line of sight and the front of the board becomes a boundary line. An adsorption region is formed inside the boundary line, and it is desirable that the inner side of the boundary is occupied by the adsorption region. Further, the condensation region includes a region outside the boundary, and is preferably limited to the outside of the boundary. Thus, the outer peripheral portion of the front surface of the cryopanel 50 is distinguished into an adsorption region and a condensation region.

Fig. 5 is a view showing a cryopump shown in Fig. 4 for explaining an adsorption region formed in the cryopanel 50. In Figure 5, for illustration The first line of sight 70 and the second line of sight 72 of the shroud front end 33 are exemplified by broken arrows. The first line of sight 70 is the line of sight toward the outer end of the small cryopanel 60 that is furthest from the shroud opening 31 or the shroud front end 33. The second line of sight 72 is a line of sight toward the outer end of the intermediate low temperature plate 62 closest to the shroud opening 31 or the shroud front end 33. As described above, the small cryopanel 60 farthest from the shroud opening 31 is adjacent to the intermediate cryopanel 62 closest to the shroud opening 31.

The trajectory of the first line of sight 70 closest to the front surface of the intermediate low temperature plate 62 of the shroud opening 31 provides the boundary 84 between the suction region 74 and the condensation region 78 of the front side of the intermediate low temperature plate 62. Further, next to the trajectory of the second line of sight 72 of the front surface of the intermediate-type cryopanel 62 adjacent to the shroud opening 31, the boundary 86 between the suction region 76 and the condensing region 82 of the front surface of the intermediate-type cryopanel 62 is provided. Similarly, the remaining medium-sized cryopanel 62, small-sized cryopanel 60, and large cryopanel 64 can also determine the boundary between the adsorption region and the condensation region.

Fig. 6 is a plan view showing the front surface of the panel of the cryopanel 50 for the cryopump 10 shown in Figs. 4 and 5. In order to mount the board mounting member 52, a notch portion 88 is formed in the cryopanel 50 from a part of the outer portion to the center portion. The boundary line 86 determined by the second line of sight 72 of Fig. 5 is shown as an example in Fig. 6. Corresponding to the shroud opening 31 and the cryopanel 50 are circular, the boundary line 86 also draws a circle in front of the panel. In this case, the boundary line 86 shows the adhesion limit radius of the adsorbent. By adhering the adsorbent to the entire inner side of the adhesion limit radius, it is possible to mount the most adsorbent on the front surface of the board without exposing the adsorbent when it is confirmed from the shroud opening 31.

Fig. 7 is a view showing the back surface of the cryopanel 50 shown in Fig. 6. As mentioned above, the adsorbent can be applied to the entire area on the back side of the plate, or as the seventh As shown in the figure, the outer peripheral end of the back surface is slightly vacant. Such a narrow sorbent detachment region may also be provided, for example, in consideration of the height of the adsorbent to be adhered, for example, activated carbon particles, and in order to surely prevent it from being exposed to the shroud opening 31.

As described above, in the low-temperature adsorption plate 50, the adsorbent-shedding region is formed on the surface common to the region where the adsorbent is present. Common faces are, for example, planes, more specifically front of the board or back of the board. The adsorbent falling-off region exposes a surface of the cryopanel substrate such as a metal surface for low-temperature coagulation. The adsorbent detachment region is located at a peripheral exposed portion confirmed by the cryopump opening 31.

The activated carbon particles on the cryopanel 50 are then formed into, for example, a cylindrical shape. A plurality of activated carbon particles are successively arranged in a state of being arranged in an irregular arrangement in a state of being densely arranged on the surface of the cryopanel 50. Further, the shape of the adsorbent may be non-cylindrical, and may be, for example, a spherical shape or other formed shape or an indefinite shape. The arrangement of the adsorbents on the plates may be a regular arrangement or an irregular arrangement.

In the embodiments of Figures 2 and 4, at least 60% or at least 70% of the total area of the front and back faces of the plurality of cryopanels 50 is covered by the adsorbent. By setting the center portion of the cryopanel 50 at least at the upper side (opening side) as the adsorbent existence region, at most 90% or at most 80% of the total area of the front and back surfaces of the plurality of cryopanels 50 is covered by the adsorbent Preferably. It is also possible to cover 65 to 85% of the total area of the front and back sides of the plurality of cryopanels 50 by the adsorbent.

Further, in the embodiments of Figs. 2 and 4, at most 40% or at most 30% of the total area of the front and back surfaces of the plurality of cryopanels 50 is a region where the adsorbent falls off. By lowering the upper (open side) cryopanel 50 The outer peripheral portion is provided as an adsorbent shedding region, so that at least 10% or at least 20% of the total area of the front and back surfaces of the plurality of cryopanels 50 is preferably a adsorbent shedding region. 15 to 35% of the total area of the front and back surfaces of the plurality of cryopanels 50 may also be the adsorbent shedding region.

Particularly in the cryopanel assembly 14 comprising the intermediate cryopanel 62, at least 60% or at least 70% of the total surface area of the intermediate cryopanel 62 is preferably covered by the adsorbent. The respective faces of the plates of the medium-sized cryopanel 62 may be covered with at least 60% or at least 70% by the adsorbent. For both sides of the panels or as a total of a plurality of panels, at least 60% or at least 70% may be covered by the adsorbent. Further, by providing the outer peripheral portion as the adsorbent falling-off region, it is preferable to cover the outer surface of the medium-sized cryopanel 62 by 90% or less or 80% or less with the adsorbent. The medium-sized cryopanel 62 has a sorbent coating ratio of 65 to 85%.

In this case, it is preferable that the small-sized cryopanel 60 has a sorbent coating ratio equal to or smaller than the medium-sized cryopanel 62. For example, the small cryopanel 60 has a sorbent coating ratio of 50 to 65%. The large cryopanel 64 has a sorbent coating ratio equal to or larger than the medium-sized cryopanel 62. For example, the large cryopanel 64 has a sorbent coating ratio of 85 to 100%. The entire area of both sides of the large cryopanel 64 can also be covered by the adsorbent.

Fig. 8 and Fig. 9 are tables showing an example of the adsorbent shedding rate or the coverage ratio of the cryopanel assembly 14 according to the embodiment of the present invention. The small-sized cryopanel 60, the medium-sized cryopanel 62, and the large-sized cryopanel 64 show the drop rate and the coverage of the adsorbent, respectively. About the total of each sheet and group The drop rate and coverage rate are displayed. Figure 8 shows the front and back, respectively, and Figure 9 shows the total of the front and back.

In the eighth and ninth drawings, the small-sized cryopanel 60, the medium-sized cryopanel 62, and the large-sized cryopanel 64 are respectively labeled as one group, two groups, and three groups. In the present embodiment, one group, two groups, and three groups each include three sheets, four sheets, and three sheets, and a total of ten sheets are included. These sheets are arranged in the same arrangement as the cryopanel assembly 14 shown in FIG. In Fig. 8, the thin plates No. 1 to No. 10 are respectively attached to display the respective thin plates.

In this embodiment, each of the sheets is a metal, the adsorbent is particulate activated carbon, and the activated carbon is attached to the metal surface by an adhesive. Therefore, the area of the metal portion shown in Fig. 8 is the area of the front surface and the back surface of the display sheet. The area of the activated carbon portion is zero when the surface is not provided with activated carbon, and when the entire surface is covered with activated carbon, the area of the metal portion is equal to the area of the metal portion, and when there is a region where the activated carbon is detached, Become the intermediate value of these. The area ratio of the activated carbon portion occupied by the metal portion area is the coverage ratio, and the ratio of the remaining area occupied by the metal portion area is the drop rate.

In addition, the three thin plates of the small cryopanel 60 are all the same diameter. The area of the top sheet (sheet number 1) closest to the opening in the group 1 is larger than the area of the sheet (the sheet number 2, 3) directly below it, because the sheet numbers 2, 3 have the notch portion 88 as shown in Fig. 6. And the top sheet is not for the sake of it. That is, the area of the top sheet is only as large as the area of the notch portion 88.

Regarding the front surface of the thin plate, as in the embodiment shown in Fig. 6, the thinning is adjacent by the front side of the thin plate and from the front end 33 of the shroud toward the front side thereof. The inside of the boundary determined by the intersection of the line of sight at the end of the plate, followed by activated carbon. However, the front side of the top sheet (the sheet number 1) closest to the opening in the group is not provided with activated carbon to expose the metal surface. Regarding the thin plate (thin plate number 2) directly underneath, the activated carbon was not provided in front of it to expose the metal surface. This is because the line of sight from the front end 33 of the shroud does not intersect the sheet surface (i.e., the entire front area is visible from the front end 33 of the shroud).

The entire inner side of the boundary where the activated carbon occupies the boundary determined by the line of sight is the thin plate (thin plate number 3) which is the farthest from the opening in the group, and the thin plate (the thin plate number 4) which is the closest to the opening among the two groups, in the two groups. Next, the thin plate (thin plate number 5) close to the opening, the thin plate (the thin plate number 8) closest to the opening among the three groups, and the thin plate (thin plate number 9) which is next to the opening among the three groups.

In terms of the efficiency of the production, the two thin sheets (the thin sheets No. 6 and No. 7) in the two groups are set to be the same as the thin sheet (the thin sheet No. 5) directly above, and the thinnest sheet in the three groups (the thin sheet No. 10) It is set to be the same as the thin plate (thin plate No. 9) directly above it. Therefore, these sheets have a substantial outer circumference of the activated carbon portion at a slightly inner side than the boundary determined by the line of sight. Regarding these thin plates, the active carbon portion can be slightly enlarged by the boundary between the line of sight and the outer circumference of the substantially activated carbon portion.

Regarding the back surface of the thin plate, unlike the embodiment shown in Fig. 7, the activated carbon detachment region was not provided at the outer peripheral end but the activated carbon was adhered to the entire region. Therefore, the area of the metal portion on the back surface and the area of the activated carbon portion are equal.

When the small time of each group shown in Fig. 9 was observed, the active carbon coverage rate of one group was 50%, the two groups were 77%, and the three groups were 87%, which gradually became larger. The activated carbon coverage of the entire cryopanel assembly 14 was 76%.

As shown in FIGS. 2 and 4, the back surface and the other front surface of one of the adjacent two cryopanels 50 extend in parallel toward the side surface of the radiation shield 16, and an open portion 54 is formed therebetween. The open portion 54 is toward the radiation shield 16 and is continuous with the open space 30. The outer peripheral side of the open portion 54 is a gas inlet continuous to the open space 30, and the inner peripheral side of the open portion 54 is closed by the adjacent two cryopanels 50 and the plate mounting member 52.

The cryopanel 50 is densely arranged in the direction of the central axis of the shield so that the depth of the open portion 54 becomes larger than the interval between the adjacent two cryopanels 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 board mounting member 52. When the size of the adjacent two cryopanels 50 is different, the distance from the outer peripheral end of the smaller one of the cryopanel to the panel mounting member 52 is the depth of the open portion 54. With such a dense plate arrangement, more adsorbent can be mounted in a limited space inside the cryopump.

Since the 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 exposed to the radiation shield 16 or the shroud opening 31. Gas molecules that are directed toward the cryopump 10 pass through the open region 35 around the louver 32 and enter the interior open space 30. The non-condensable gas such as hydrogen gas is reflected by the shield surface or the plate surface into the open portion 54 and reaches the adsorbent. The openness of the inside of the cryopump from the open region 35 through the open space 30 and continuously to the open portion 54 promotes gas from the outside to the adsorption region. this is okay A cryopump 10 having a high hydrogen capture probability of at least 30% is achieved.

The hydrogen capture probability is obtained by the ratio of the actual hydrogen venting velocity to the theoretical maximum hydrogen venting velocity in a cryopump having the same diameter as the cryopump 10 (i.e., the cryopump opening area is the same). The actual hydrogen exhaust velocity of the cryopump can be determined by the conventional Monte Carlo simulation method.

Also, the theoretical hydrogen venting velocity can be considered to be equal to the conductivity of the molecular flow with respect to its opening. The electrical conductivity C (hydrogen) of hydrogen is determined by the following equation from the electrical conductivity C (20 ° C air) of air at 20 °C.

Where T is the temperature (K) of the hydrogen gas and M is the molecular weight of the hydrogen (ie, M=2). The conductivity C (20 ° C air) of air at 20 ° C is proportional to the opening area A (m ² ) and is obtained by C (20 ° C air) = 116 A. In the case of, for example, a cryopump having a diameter of 250 mm, theoretically, the hydrogen gas exhaust velocity is about 20,840 L/s as determined by the above equation. At this time, the hydrogen capture probability is 30% and the cryopump hydrogen exhaust velocity is about 6252 L/s, which are equivalent.

A typical cryopump for hydrogen high-speed exhaust gas is designed to increase the exhaust velocity by charging more cryogenic plates, that is, activated carbon, to a cryopump. Therefore, an increase in the exhaust speed is associated with an increase in the weight of the plate and an increase in the regeneration time (especially the cooling time). To increase the exhaust speed while suppressing the increase in cooling time, you need Freezer with higher refrigeration capacity. Therefore, energy saving performance may be sacrificed due to an increase in exhaust speed.

On the other hand, an embodiment of the present invention provides a new design idea of optimizing hydrogen gas exhaust efficiency in a cryopump for high-speed hydrogen gas exhaust. The inventors have defined the ratio of the hydrogen gas discharge velocity (L/s) of the cryopump to the adsorption zone area (mm ² ), that is, the exhaust velocity per unit area in the region where the adsorbent is present, as the hydrogen exhaust efficiency of the cryopump. (L/s‧mm ² ). Instead of simply increasing the adsorbent, the exhaust gas efficiency is increased by slightly reducing the area of the adsorption zone. As described above, the area of the adsorption area can be reduced in the outer peripheral portion of the cryopanel, and the area of the adsorption area can be reduced in other portions.

When the area of the adsorption area is slightly reduced, the hydrogen gas discharge speed of the cryopump is also somewhat reduced. However, it is not really a big problem to examine these circumstances. Even if there is a difference in exhaust speed in the cryopump unit, there is a tendency that the difference in exhaust velocity which is actually produced as a result becomes smaller when the cryopump is actually mounted in the vacuum chamber. This is because, due to the limitation of the conductivity based on the vacuum chamber side, the exhaust velocity performance when viewed from the cryopump unit does not necessarily have to be performed as it is.

According to the experience and investigation of the present inventors, in the cryopump for high-speed hydrogen gas exhaust, even if there is a 10% difference in exhaust gas velocity performance in the cryopump unit, the exhaust gas installed in the vacuum chamber is hardly affected. Speed performance. Therefore, when the allowable range of the reduction of the hydrogen gas discharge rate is set to be within 10%, the advantage of improving the hydrogen gas exhaust efficiency by reducing the area of the adsorption zone is superior to the drawback of the reduction of the exhaust velocity. Therefore, in an embodiment of the present invention, it is possible to cover the entire surface of the cryopanel with the adsorbent provided. The area of the adsorption region is adjusted in such a manner that the hydrogen gas exhaust efficiency is improved under the condition of an exhaust gas velocity of at least 90% of the hydrogen gas discharge rate.

According to the analysis by the inventors of the present invention, for example, in a cryopump having a plate array of a plurality of flat plates parallel to the opening of the type shown in Figs. 2 and 4, when the entire surface of the cryopanel is covered with the adsorbent, hydrogen gas is used. The exhaust efficiency is limited to about 2 × 10 ^-2 L / s ‧ mm ² ~ 4 × 10 ^-2 L / s ‧ mm ² . On the other hand, in the examples shown in FIGS. 2 and 4, the hydrogen gas exhaust efficiency can be improved to 5 × 10 ^-2 L/s ‧ mm ² or more by providing the detached portion of the adsorbent. The hydrogen gas exhaust efficiency can be increased to 7 × 10 ^-2 L / s ‧ mm ² within the allowable range of reduction in the hydrogen gas discharge rate.

That is, the hydrogen exhaust efficiency is approximately doubled. This means that the hydrogen exhaust velocity of the same segment can be achieved in about half of the adsorption zone. Thereby, the weight of the board can be reduced by about 1000 to 2000 g. If the weight of the board is reduced, the time required for cooling will also be shortened. As a result, the average power consumption during regeneration can be reduced by about 40%.

In addition, in order to make the hydrogen gas exhaust efficiency higher than 7 × 10 ^-2 L / s ‧ mm ² , the actual method should be a low-temperature plate assembly of a type that completely exposes the adsorbent (for example, refer to Patent Document 4 (Japanese Patent Laid-Open No. 2009) -162074 bulletin)). The entire contents are referred to in the specification of the present application by referring to Japanese Laid-Open Patent Publication No. 2009-162074.

Further, the molecular system of the condensable gas that has flowed from the outside toward the cryopump 10 passes through the open region 35 around the louver 32 in a straight line to the condensed region of the outer periphery of the radiation shield 16 or the cryopanel 50 and is captured on these surfaces. on. The open partial space 54 is a gas inlet except for the outer peripheral side. The remaining portion is blocked by the cryopanel 50 on the upper side from the cryopump opening 31, and the adsorption region is housed in the blocking portion. The hard-to-regenerate gas is almost no exception to a condensable gas. By preventing the adsorption region from being directly exposed to the cryopump opening 31, the adsorption region is protected from the hard-to-regenerate gas contained in the gas entering the cryopump 10. The difficult regeneration gas system is deposited in the condensation zone. In this way, it is possible to achieve both high-speed exhaust gas of the non-condensable gas and protection of the adsorption region from the non-renewable gas.

In an embodiment of the present invention, the adsorption region is housed in the shielding portion so that it cannot be confirmed from the cryopump opening 31. In other words, the ratio of the adsorbent area that can be confirmed from the cryopump opening 31 to the total adsorbent area of the cryopanel 50, that is, the "adsorbent visibility" is zero. However, the cryopump according to an embodiment of the present invention is not limited to a structure in which the visibility of the adsorbent is zero%. When the visibility of the adsorbent is less than 7%, it can be substantially evaluated that the adsorbent cannot be confirmed from the opening. In one embodiment, it is preferred that the adsorbent has a visibility of less than 7%, less than 5%, or less than 3%. However, for example, when it is estimated that the content of the hardly regenerating gas is very low or that the exposed adsorbent is allowed to be sacrificed, more than 7% of the adsorbent can be seen from the opening.

It is difficult for gas molecules to reach the cryopanel 50 inside the radiation shield 16 away from the cryopump opening 31 as compared to the cryopanel 50 near the cryopump opening 31. The cryopanel 50 remote from the cryopump opening 31 has a small effect on the exhaust velocity and the effect of the hard-to-regenerate gas is also small. Therefore, in an embodiment, the large-sized cryopanel 64 on the lower side may be provided with an adsorbent at a peripheral exposed portion. For example, in the embodiment shown in Fig. 8, the visibility of the adsorbent in the case where the adsorbent is provided over the entire front surface of the large cryopanel 64 is about 7%.

Hereinafter, the operation of the cryopump 10 will be described. When the cryopump 10 is actuated, First, before the operation is performed, the inside of the vacuum chamber 80 is roughly pumped to about 1 Pa to 10 Pa by using another appropriate rough pump. The cryopump 10 is then actuated. The first cooling stage 22 and the second cooling stage 24 are cooled by the driving of the refrigerator 12, and the radiation shield 16, the louver 32, and the cryopanel assembly 14 thermally connected to the cooling stages are also cooled. The first cryopanel includes a radiation shield 16 and a louver 32, and the second cryopanel includes a cryopanel assembly 14.

The cooled louver 32 cools the gas molecules that have flown from the vacuum chamber 80 into the inside of the cryopump 10, and condenses a gas (for example, moisture or the like) whose vapor pressure is sufficiently lowered at the cooling temperature to the surface to be exhausted. The gas whose vapor pressure is not sufficiently lowered at the cooling temperature of the louver 32 enters the inside of the radiation shield 16 through the louver 32. When the gas molecules passing through the louver 32 contain a gas (for example, argon gas or the like) whose vapor pressure is sufficiently lowered at the cooling temperature of the cryopanel assembly 14, the condensed gas is condensed on the surface of the cryopanel assembly 14 to be exhausted. Even a gas (for example, hydrogen or the like) whose vapor pressure is not sufficiently lowered at the cooling temperature is exhausted by being adsorbed by the adsorbent adhering to the surface of the cryopanel assembly 14 and being cooled. As such, the cryopump 10 can bring the degree of vacuum inside the vacuum chamber 80 to a desired level.

In the cryopump 10 used in the vacuum evacuation system of the ion implantation apparatus, the hard-to-regenerate gas such as an organic gas or a dopant gas in the gas entering the radiation shield 16 is condensed on the outer peripheral portion of the cryopanel 50. The adsorbent is detached from the site. A gas having a relatively small molecular diameter such as hydrogen gas is adsorbed to the adsorbent. The cryopump treatment is performed in this way.

When the cryopump process is continued, the gas is accumulated in the cryopump unit. The regeneration process is performed in order 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. Next, the cryopanel 50 is heated. The cryopanel 50 is heated to a temperature higher than the cooling temperature in the cryopump processing (for example, normal temperature).

By raising the temperature, the gas trapped on the surface of the cryopanel by condensation is vaporized, and the gas trapped by the adsorption is released and discharged into the interior of the pump vessel. The re-discharged gas passes through the discharge port (not shown) of the cryopump 10, and is discharged to the outside, for example, by the drive of the attached rough pump. Thereafter, the cryopanel 50 is re-cooled to the operating temperature at which the cryopump is processed. The regeneration process is completed by re-cooling. The gate valve 7 is opened and the cryopump processing is started again. In this way, cryopump processing and regeneration processing are performed interactively.

Fig. 10 is a view showing a change in the hydrogen gas discharge speed of the cryopump that has passed through the regeneration according to an embodiment of the present invention. Fig. 10 is a view showing a change in the hydrogen gas discharge rate of the cryopump 10 according to the embodiment of the present invention. For comparison, for example, a change in the hydrogen gas discharge rate of the cryopump having the cryopanel assembly of the type in which the adsorbent is completely exposed as disclosed in Japanese Laid-Open Patent Publication No. 2009-162074 is shown. The vertical axis of Fig. 10 shows the measured value of the hydrogen exhaust gas velocity, and the horizontal axis shows the number of regenerations. The measured value of the exhaust velocity on the solid line is the value before the regeneration process is to be performed, and the measured value on the broken line is the value immediately after the regeneration is completed.

Regarding the first regeneration shown in Fig. 10, the measured value on the broken line is the value when the cryopump was first operated. Since the activated carbon was not contaminated by the hard-to-regenerate gas, the completely exposed type of the comparative example showed a particularly high hydrogen gas discharge rate.

It is predicted that the exhaust velocity is lower before regeneration and recovered after completion. However, as shown in the comparative example, even if the exhaust gas velocity is reduced and recovered repeatedly after the third regeneration, the exhaust gas velocity rapidly decreases from the initial high exhaust gas velocity before the second regeneration. It can be considered that the exhaust gas velocity will continue to decrease until the exposed activated carbon is contaminated to some extent. Even after the regeneration, the initial exhaust performance cannot be restored.

However, in the embodiment, the increase and decrease of the exhaust velocity are performed from the first regeneration to the seventh regeneration. Even if the regeneration is repeated, as shown by the thick broken line shown in the figure, the hydrogen exhaust velocity of about a constant level is maintained. By regeneration, the initial exhaust performance is restored. That is, it can be known that the stable exhaust performance is continuously maintained from the initial operation after the cryopump is shipped.

Fig. 11 is a flow chart for explaining a method of manufacturing the cryopump 10 according to an embodiment of the present invention. This method is carried out by the operator or by the manufacturing apparatus in the manufacturing process of the cryopump 10. Before the masking process, the substrate is processed by the base material to process the substrate of the cryopanel (S10). As shown in Fig. 11, the substrate of the cryopanel 50 is subjected to a masking process (S12). The masking process includes a process of masking exposed portions of the substrate that are not obscured by other cryopanels (eg, cryopanels adjacent to the assembly of the cryopanel assembly 14). The masking process includes a process of attaching a masking tape to such exposed portions, for example.

Next, the adsorbent for the surface of the unmasked substrate followed by the adsorbent is then treated (S14). The subsequent treatment comprises a treatment of applying an adhesive to the surface of the substrate that is not masked, and an adsorbent such as granular activated carbon in the adhesive application region. Next, the cryogen plate 50 with adsorbent Mounted to the board mounting member 52, the cryopanel assembly 14 is assembled (S16). The cryopanel assembly 14 is attached to the refrigerator 12 of the cryopump 10, and the cryopump 10 is assembled (S18).

Further, before the mask processing, the lower temperature plate 50 may be first subjected to a process of observing the line from the front end of the radiation shield 16 to the end of the cryopanel 50 adjacent to the cryopanel 50. The outer side of the boundary determined by the intersection of the cryopanel 50 is a mask region. This decision processing can also be carried out in the design process of the pre-stage of the manufacturing process.

Fig. 12 is a flow chart for explaining a method for manufacturing the cryopump 10 of one embodiment of the present invention. This method is performed, for example, for designing the cryopanel assembly 14. First, the low temperature plate structural parameter value (S20) of the maximum hydrogen exhaust velocity provided when the structural parameters of the cryopanel are changed under certain restrictions is obtained. The plate structure parameter can also be set as a variable and the hydrogen exhaust velocity can be set as the objective function, and the plate structure parameter value for providing the maximum hydrogen exhaust velocity can be obtained by a conventional experimental planning method.

The restriction includes detaching the adsorbent from a portion of the surface of the cryosorption plate. The adsorbent shedding condition may be such that an adsorption region is formed on the inner side of the boundary defined by the line of sight from the front end of the radiation shield 16 to the end of the cryopanel 50 adjacent to the cryopanel 50 and the front of the cryopanel. .

The plate structure parameters include the dimensions of the cryosorption plate, such as the plate diameter if the plate is circular. Where the cryopanel assembly 14 comprises a plurality of cryopanels of different shapes, a plurality of parameters for displaying the respective shapes may also be used. Where the cryopanel assembly 14 comprises a plurality of different diameter cryopanels, the panel structural parameters may also include the diameter of each panel. Board structure parameters, It may also include the spacing of the cryopump opening 31 and the top plate. The plate structure parameters may also include the diameter of the louver 32. The structural parameters of the board may also include adjacent cryopanel spacing.

Based on the plate structure parameter values thus obtained, the structure of the arrangement of the cryosorption plates is determined (S22). For example, a value of a cryopanel size such as a plate diameter which provides a maximum hydrogen exhaust velocity under conditions in which the adsorbent is detached from a portion of the surface of the cryosorption plate is obtained. The specific structure of the cryopanel assembly 14 can be determined using this value.

Hereinabove, the present invention has been described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and those skilled in the art can understand that various modifications can be made and various modifications can be made, and such modifications are also included in the scope of the present invention.

A plate arrangement different from the above embodiment may also be employed. For example, the cryopanel spacing may be equal in all panels or may be different. For example, a plurality of plates 50 may be disposed in such a manner that the plate spacing is narrowed as the plate position is separated from the opening 31. Thereby, the fluidity in the region close to the opening 31 can be made good and the exhaust velocity can be increased. At the same time, by arranging the plates relatively densely in the region away from the opening 31, the adsorption region can be increased, so that a sufficient amount of gas storage can be secured.

Further, a cryopanel 50 having a shape and/or orientation different from that of the above embodiment may be employed. For example, the radial length of the plate 50 may be shortened as it moves away from the opening 31, or may be made equal. The shape when the plate 50 is confirmed from the opening 31 may be non-circular, and may be other shapes such as a polygonal shape. The plate 50 may have a curved portion facing upward or downward at the peripheral portion, for example. Minute. Plate 50 may also have openings or slits on the surface to promote gas flow. The direction of the plate 50 may be inclined so as to be 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, the exposed surface other than the cryopanel 50 in the cryopanel assembly 14 may be used as an adsorbent adhesive surface. For example, the board mounting member 52 can be utilized as one of the boards.

1‧‧‧Ion implantation device

10‧‧‧Cryogenic pump

12‧‧‧Freezer

14‧‧‧Low temperature plate assembly (low temperature adsorption plate arrangement, low temperature plate arrangement)

16‧‧‧radiation shield

22‧‧‧1st cooling station

24‧‧‧2nd cooling station

30‧‧‧Open space inside the cryopump (open space, internal space, open partial space, open partial space, internal open space)

31‧‧‧Cryogenic pump opening (opening, shroud opening)

32‧‧‧Blinds

33‧‧‧Shield front end

35‧‧‧Open area

50‧‧‧Cryogenic plate (plate, low temperature adsorption plate)

52‧‧‧ board mounting components

54‧‧‧Open part (opened partial space, open partial space, partial space)

60‧‧‧ top board (small low temperature board)

62‧‧‧Intermediate board (medium low temperature board)

64‧‧‧lower side panel (large cryogenic panel)

76‧‧‧Adsorption area

82‧‧‧ Condensation area

86‧‧‧Boundary (boundary line)

100‧‧‧CP controller

Fig. 1 is a view schematically showing an ion implantation apparatus and a cryopump according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view schematically showing a cryopump according to an embodiment of the present invention.

Fig. 3 is a plan view schematically showing a cryopump according to a preferred embodiment.

Fig. 4 is a cross-sectional view schematically showing a cryopump according to a preferred embodiment.

Fig. 5 is a view for explaining the adsorption region formed on the cryopanel according to the cryopump shown in Fig. 4.

Fig. 6 is a plan view showing the front side of the plate of the cryogenic pump showing the cryopanel shown in Figs. 4 and 5.

Fig. 7 is a view showing the back side of the cryopanel shown in Fig. 6.

Fig. 8 is a table showing an example of the adsorbent shedding rate or the coverage ratio of the cryopanel assembly according to the embodiment of the present invention.

Fig. 9 is a table showing an example of the adsorbent shedding rate or the coverage ratio of the cryopanel assembly according to the embodiment of the present invention.

Fig. 10 is a view showing a change in the hydrogen gas discharge speed of the cryopump by the regeneration according to an embodiment of the present invention.

Fig. 11 is a flow chart for explaining a method of manufacturing a cryopump according to an embodiment of the present invention.

Figure 12 is a flow chart for explaining a method for manufacturing a cryopump according to an embodiment of the present invention.

10‧‧‧Cryogenic pump

33‧‧‧Shield front end

35‧‧‧Open area

31‧‧‧Cryogenic pump opening

32‧‧‧Blinds

14‧‧‧Cryogenic plate assembly

36‧‧‧Flange

30‧‧‧Cryogenic pump interior open space

54‧‧‧open section

70‧‧‧1st line of sight

72‧‧‧2nd line of sight

78‧‧‧Condensation area

82‧‧‧ Condensation area

86‧‧‧ border

84‧‧‧ border

74‧‧‧Adsorption area

76‧‧‧Adsorption area

60‧‧‧ top board

62‧‧‧Intermediate board

64‧‧‧lower side panel

34‧‧‧ pump casing

28‧‧‧The Department of Occlusion

12‧‧‧Freezer

52‧‧‧ board mounting components

50‧‧‧Cryogenic sheet

16‧‧‧radiation shield

Claims (19)

A cryopump characterized by comprising: a refrigerator including a first cooling stage for supplying a first cooling temperature; and a first cooling stage for supplying a non-condensable gas lower than the first cooling temperature a second cooling stage having a cooling temperature; a radiation shield comprising a shield front end forming an opening for receiving a gas, the radiation shield being thermally connected to the first cooling stage and surrounding the second cooling stage; and a cryopanel assembly Thermally connected to the second cooling stage, an open space facing the opening is formed between the outer peripheral portion and the radiation shield, and at least a part of the shroud front end can be confirmed, and the low temperature plate assembly includes a top plate and an intermediate plate. Facing the opening, the intermediate plate includes a front surface of the plate facing the opening and disposed opposite to the top plate on the opposite side of the opening, and between the low temperature plate adjacent to the front surface of the plate of the intermediate plate and the front surface of the plate is formed with Continuing with the open portion of the open space, the depth of the open portion is greater than the spacing between the adjacent cryopanel and the front of the panel, the intermediate panel having a non-condensable gas in front of the panel Attachment region, the suction region of the inner boundary line is formed by the front end of the radiation shield from said distal end adjacent to the line of sight and the cryopanel is determined the intersection board. The cryopump according to claim 1, wherein the adsorption region is in front of the plate and occupies a region inside the boundary. The cryopump according to claim 1, wherein The intermediate plate has a condensation region for a condensable gas on its surface, and the condensation region includes a region outside the aforementioned boundary in the front surface of the aforementioned plate. The cryopump according to the first aspect of the invention, wherein the outer peripheral portion of the intermediate plate is parallel to the top plate and extends to a position closer to the radiation shield than the outer peripheral portion of the top plate. The cryopump according to claim 1, wherein the cryopanel assembly further includes a lower side plate disposed opposite to the opening of the intermediate plate, the outer peripheral portion of the lower side plate being parallel to the intermediate plate And extending to a position closer to the radiation shield than the outer peripheral portion of the intermediate plate. The cryopump according to claim 1, wherein the intermediate plate includes a plurality of thin plates each including a front surface facing the opening and a back surface facing the opposite side of the opening, and arranged in parallel with each other. The cryopump according to claim 1, wherein the cryopump further includes a louver thermally coupled to the radiation shield and disposed in the opening, the louver having an intermediate dimension between the top plate and the intermediate plate, An open area is formed between the outer peripheral portion of the louver and the radiation shield. The cryopump according to claim 1, wherein at least 70% of the surface area of the intermediate plate is covered by an adsorbent capable of adsorbing hydrogen, and the cryopump has a hydrogen capture probability of at least 30%. , The adsorbent is contained in the open portion, and the ratio of the adsorbent area confirmed from the opening to the total area of the adsorbent, that is, the adsorbent visibility is less than 7%. A cryopump having a radiation shield and a cryopanel assembly, wherein the cryopanel assembly is disposed in the radiation shield from a front side toward a deep portion and has a front surface facing the opening of the radiation shield and facing the opening Arranging a plurality of cryopanels on the opposite side of the opposite side, and forming an open space toward the opening between the outer peripheral portion of the plurality of cryopanels and the radiation shield, wherein the cryopanel assembly is At least 70% of the total area of the front and back surfaces of the plurality of cryopanels is covered by a adsorbent capable of adsorbing hydrogen, the cryopump having a hydrogen capture probability of at least 30%, and the adsorbent being contained in the plurality of low temperatures Between the back surface of each of the plates and the front surface of the cryopanel adjacent to the deep portion of the cryopanel, the ratio of the adsorbent area confirmed from the opening to the total adsorbent area of the plurality of cryopanels, that is, the adsorbent visibility is less than 7%. The cryopump according to claim 9, wherein, in the arrangement of the plurality of cryopanels, at least a part of the deep cryopanel is blocked from the opening by the cryopanel directly in front, and the adsorbent is disposed in the The blocking portion of the cryopanel is such that it cannot be confirmed from the aforementioned opening. The cryopump according to claim 9, wherein the total adsorbent area is 90% or less of a total area of the front surface and the back surface of the plurality of low temperature sheets. The cryopump according to claim 9, wherein at least 90% of the adsorbent is exposed to the radiation shield or the opening. A cryopump characterized by comprising: an arrangement of a plurality of cryosorption plates surrounded by an open space inside a cryopump open to a cryopump opening; and a radiation shield surrounding an open space inside the cryopump, the plurality of low temperatures At least one of the adsorption plates includes an end of the plate that protrudes toward the interior of the cryopump and faces the radiation shield, and the end of the plate has a region where the adsorbent falls off. The cryopump according to claim 13, wherein the adsorbent shedding zone is formed on a face common to the region in which the adsorbent is present. The cryopump according to claim 13, wherein the adsorbent shedding zone exposes the surface of the cryopanel substrate for low temperature condensation. The cryopump according to claim 13, wherein the adsorbent shedding zone is located at a peripheral exposed portion that is identifiable through the cryopump opening. A method of manufacturing a cryopump, comprising: a step of masking a substrate of the cryopanel; and a step of adhering the adsorbent to a surface of the substrate that is not masked. The method for manufacturing a cryopump according to claim 17, wherein The step of performing the aforementioned masking includes masking the exposed portions of the aforementioned substrate that are not blocked by other cryopanels. The method for manufacturing a cryopump according to claim 17, wherein the method for manufacturing the cryopump further comprises: a cryopanel for arranging the plurality of cryopanels, from the front end of the radiation shield to The outer side of the boundary defined by the line of sight of the end of the cryopanel adjacent to the cryopanel and the intersection of the cryopanel is determined as a masking area.