TWI580865B - Low temperature pump - Google Patents

Description

Cryopump

The present invention relates to a cryopump.

Cryopumps generally have two cryopanels with different temperatures. The gas is condensed on a low temperature cryostat. With the use of cryopumps, the condensed layer gradually grows on the low temperature and low temperature plates, and may soon come into contact with the high temperature cryopanel. As a result, at the contact portion between the high temperature and low temperature plate and the condensation layer, the gas is vaporized again and released to the surroundings. In the future, the cryopump will not be able to fully play its original role. Therefore, the amount of gas stored at this time is given to the maximum storage amount of the cryopump.

(previous technical literature) (Patent Literature)

Patent Document 1: Japanese Laid-Open Patent Publication No. 2009-275672

One of the exemplary purposes of one aspect of the present invention is to increase the amount of gas stored in a cryopump.

A cryopump according to an aspect of the present invention includes: a refrigerator including a first cooling stage and a second cooling stage cooled to a temperature lower than the first cooling stage; and the first cryopanel having a radiation shielding of the main opening The cover and the inlet cryopanel disposed in the main opening are thermally connected to the first cooling stage; and the second cryopanel is surrounded by the first cryopanel and thermally connected to the second cooling stage. The radiation mask includes a mounting seat located on a side of the second cryopanel and configured to mount the refrigerator on the radiation mask, and a mask portion adjacent to the mount and surrounding the foregoing 2 low temperature plate. A side gap is formed between the second cryopanel and the mount, and a gap portion continuous with the side gap is formed between the second cryopanel and the mask portion, and the second cryopanel is formed The shape or arrangement is adjusted such that the width of the aforementioned side gap coincides with the width of the aforementioned gap portion.

Further, a technique of replacing the constituent elements or expressions of the present invention with each other among methods, apparatuses, systems, and the like can also be effectively employed as an aspect of the present invention.

According to the present invention, the amount of gas stored in the cryopump can be increased.

10‧‧‧Cryogenic pump

16‧‧‧Freezer

18‧‧‧1st cryogenic plate

20‧‧‧2nd cryogenic plate

22‧‧‧1st cooling station

24‧‧‧2nd cooling station

26‧‧‧Mask opening

30‧‧‧radiation mask

32‧‧‧ Board components

36‧‧‧Mask side

37‧‧‧ Mounting

41‧‧‧Open ring section

42‧‧‧Mounting holes

43‧‧‧ side clearance

44‧‧‧Gap section

46‧‧‧Over the gap

48‧‧‧The gap below

50‧‧‧ board main body

52‧‧‧The outer edge of the board

54‧‧‧Small hole

56‧‧‧Gas passage area

58‧‧‧Gas isolation zone

61‧‧‧ Top surface of the top plate

62‧‧‧Central area

63‧‧‧Outer area

74‧‧‧Gap section

Fig. 1 is a side cross-sectional view showing a main part of a cryopump according to a first embodiment of the present invention.

Fig. 2 is a diagram showing the top plate of the first embodiment of the present invention. view.

Fig. 3 is a plan view showing a plate member according to a first embodiment of the present invention.

Fig. 4 is a view showing a cryopump in an exhausting operation according to the first embodiment of the present invention.

Fig. 5 is a side cross-sectional view showing a main part of a cryopump according to a second embodiment of the present invention.

Fig. 6 is a side cross-sectional view showing a main part of a cryopump according to a third embodiment of the present invention.

Fig. 1 is a side cross-sectional view showing the main part of the cryopump 10 according to the first embodiment of the present invention. The cryopump 10 is mounted, for example, in a vacuum chamber such as an ion implantation apparatus or a sputtering apparatus for raising the degree of vacuum inside the vacuum chamber to a desired level of process requirements. The cryopump 10 has an intake port 12 for receiving a gas. The gas to be discharged enters the internal space 14 of the cryopump 10 from the vacuum chamber in which the cryopump 10 is installed through the suction port 12. The first figure shows a cross section including the central axis A of the internal space 14 of the cryopump 10.

In addition, in the following, in order to facilitate understanding, the positional relationship of the components of the cryopump 10 is indicated, and terms such as "axial direction" and "radiation direction" may be used. The axial direction indicates the direction passing through the intake port 12 (the direction along the dotted line A in Fig. 1), and the radial direction indicates the direction along the intake port 12 (the direction perpendicular to the dotted line A). For convenience, sometimes it will be in the axial direction The side close to the suction port 12 is referred to as "upper" and the side farther away from the side is referred to as "lower". That is, the side closer to the bottom of the cryopump 10 is sometimes referred to as "upper" and the side closer to the lower side is referred to as "lower". In the radial direction, the side near the center of the intake port 12 (the central axis A in Fig. 1) may be referred to as "inner", and the side close to the periphery of the intake port 12 may be referred to as "outer". The direction of radiation can also be referred to as radial. In addition, this kind of performance is independent of the configuration when the cryopump 10 is installed in the vacuum chamber. For example, the cryopump 10 can also mount the suction port 12 downward in the vertical direction in the vacuum chamber.

Further, the direction around the axial direction is sometimes referred to as "circumferential direction". The circumferential direction is along the second direction of the intake port 12 and is a tangential direction orthogonal to the radial direction.

The cryopump 10 is provided with a refrigerator 16 . The refrigerator 16 is, for example, a cryogenic refrigerator such as a Gifford-McMahon type refrigerator (so-called GM refrigerator). The refrigerator 16 is a two-stage refrigerator including a first cooling stage 22 and a second cooling stage 24. The refrigerator 16 is configured to cool the first cooling stage 22 to the first temperature level and to cool the second cooling stage 24 to the second temperature level. The temperature at the second temperature level is lower than the first temperature level. For example, the first cooling stage 22 is cooled to about 65K to 120K, and is preferably cooled to 80K to 100K, and the second cooling stage 24 is cooled to about 10K to 20K.

Further, the refrigerator 16 includes a first cylinder 23 and a second cylinder 25. The first cylinder 23 connects the room temperature portion of the refrigerator 16 to the first cooling stage 22. The second cylinder 25 is a connecting portion that connects the first cooling stage 22 to the second cooling stage 24.

The cryopump 10 shown is a so-called horizontal cryopump. Horizontal cryopump Generally, the refrigerator 16 is disposed as a cryopump that intersects (usually orthogonal to) the central axis A of the internal space 14 of the cryopump 10.

The cryopump 10 includes a first cryopanel 18 and a second cryopanel 20 that is cooled to a temperature lower than the first cryopanel 18 . As will be described in detail later, the first cryopanel 18 includes the radiation mask 30 and the plate member 32 and surrounds the second cryopanel 20 . A main accommodating space 21 of a condensing layer is formed between the plate member 32 and the second cryopanel 20.

First, the second cryopanel 20 will be described. The second cryopanel 20 is provided at a central portion of the internal space 14 of the cryopump 10 . The second cryopanel 20 is attached to the second cooling stage 24 so as to surround the second cooling stage 24 . Therefore, the second cryopanel 20 is thermally connected to the second cooling stage 24, and the second cryopanel 20 is cooled to the second temperature level.

The second cryopanel 20 includes a top plate 60. The top plate 60 is directly attached to the upper surface of the second cooling stage 24 of the refrigerator 16 , and the second cooling stage 24 is located at the center of the internal space 14 of the cryopump 10 . Thus, the main accommodating space 21 of the condensing layer occupies the upper half of the internal space 14.

The top plate 60 is provided to condense gas on its surface. The top plate 60 is a portion closest to the plate member 32 in the second cryopanel 20, and has a top plate front surface 61 opposed to the plate member 32. The top front surface 61 is provided with a central area 62 and an outer side area 63 surrounding the central area 62.

The top plate 60 is a substantially flat plated cryopanel that is disposed perpendicular to the axial direction. The top plate 60 is fixed to the second cooling stage 24 in the center area 62. The central region 62 has a recess in which the top plate 60 is fixed to the second cooling stage 24 using a suitable fixing member 64 (for example, a bolt) (see FIGS. 2 and 3). Figure). A step portion 65 that faces upward is formed around the recess. The height of the step portion 65 is set to accommodate the fixing member 64 in the recess. The outer side region 63 extends radially outward from the step portion 65. The radial end of the outer side region 63 is bent downward, and the outer peripheral end portion 66 of the top plate 60 is formed. As shown in Fig. 2, the top plate 60 is a substantially disk-shaped plate.

Additionally, the top plate 60 may not have a recess that receives the central region 62 of the stationary member 64. At this time, the top plate front surface 61 may be a flat surface having no step portion 65. Further, in the present embodiment, the top plate 60 does not have an adsorbent, but an adsorbent may be provided on the back surface, for example.

Fig. 2 is a plan view showing a top plate 60 according to the first embodiment of the present invention. The shape of the second cryopanel 20 is adjusted such that the width W1 of the side gap 43 coincides with the width W2 of the gap portion 44. That is, the width W1 of the side gap 43 is substantially equal to the width W2 of the gap portion 44. For this reason, the top plate 60 has a notch portion 74 that enlarges the width of the side gap 43. The notch portion 74 has an arcuate shape. Further, regarding the lower conventional plate 67 (see Fig. 1), it is also possible to have a notch portion.

Further, the second cryopanel 20 includes one or a plurality of conventional plates 67. The conventional plate 67 is provided to condense or adsorb gas on its surface. The conventional plates 67 are arranged below the top plate 60. The shape of the conventional board 67 is different from that of the top board 60. The conventional plates 67 each have, for example, a shape of a conical trapezoidal side surface, a so-called umbrella shape. An adsorbent 68 such as activated carbon is provided on each of the conventional plates 67. The adsorbent is adhered, for example, to the back of the conventional plate 67. The purpose is to use the front surface of the conventional plate 67 as a condensation surface and the back surface as an adsorption surface.

The first cryopanel 18 is a cryopanel provided to protect the second cryopanel 20 from radiant heat from the outside of the cryopump 10 or the cryopump housing 38. The first cryopanel 18 is thermally connected to the first cooling stage 22 . Therefore, the first cryopanel 18 is cooled to the first temperature level. The first cryopanel 18 has a gap with the second cryopanel 20, and the first cryopanel 18 does not come into contact with the second cryopanel 20.

The radiation mask 30 is provided to protect the second cryopanel 20 from radiant heat from the cryopump housing 38. The radiation mask 30 is located between the cryopump housing 38 and the second cryopanel 20 and surrounds the second cryopanel 20 . The radiation mask 30 includes a mask front end 28 that partitions the mask opening 26 as a main opening, a mask bottom portion 34 that faces the mask opening 26, and a mask side portion that extends from the mask front end 28 toward the mask bottom portion 34. 36. The mask opening 26 is located at the suction port 12. The radiation mask 30 has a cylindrical shape (e.g., a cylinder) that closes the bottom portion 34 of the mask and is formed in a cup shape.

The radiation mask 30 is provided with a mount 37 of the refrigerator 16 . The mount 37 is recessed when viewed from the outside of the radiation mask 30, and a flat portion for attaching the refrigerator 16 to the radiation mask 30 is formed on the mask side portion 36. The mount 37 is located on the side of the second cryopanel 20. As described above, since the top plate 60 is directly attached to the upper surface of the second cooling stage 24 of the refrigerator 16, the top plate 60 is placed at the same height as the second cooling stage 24, and therefore the mounting seat 37 is located on the side of the top plate 60.

The mask side portion 36 forms an integrally closed annular portion. The mask side portion 36 is provided with a mount 37 and an open loop portion 41 (see Fig. 2). The open annular portion 41 is a C-shaped mask portion extending in the circumferential direction, and the mount Adjacent to 37 weeks. The open annular portion 41 surrounds the second cryopanel 20 together with the mount 37 and forms a closed annular portion. A side gap 43 is formed between the second cryopanel 20 and the mount 37, and a C-shaped gap portion 44 is formed between the second cryopanel 20 and the open loop portion 41. The gap portion 44 and the side gap 43 are continuous to form a closed annular gap. The gap portion 44 has a certain width in the circumferential direction.

As shown in Fig. 1, the mounting hole 37 has a mounting hole 42 for the refrigerator 16, and the second cooling stage 24 and the second cylinder 25 of the refrigerator 16 are inserted into the radiation mask 30 from the mounting hole 42. The first cooling stage 22 of the refrigerator 16 is disposed outside the radiation mask 30. The radiation mask 30 is connected to the first cooling stage 22 via the heat transfer member 45. The heat transfer member 45 is fixed to the outer peripheral portion of the attachment hole 42 by a flange at one end thereof, and is fixed to the first cooling stage 22 by a flange at the other end. The heat transfer member 45 is, for example, a hollow short cylinder that extends between the radiation mask 30 and the first cooling stage 22 along the central axis of the refrigerator 16 . In this manner, the radiation mask 30 is thermally connected to the first cooling stage 22. Further, the radiation mask 30 may be directly attached to the first cooling stage 22.

An upper gap 46 is formed between the second cylinder 25 and the attachment hole 42 on the side close to the mask opening 26, and a lower gap 48 is formed on the side away from the mask opening 26. The freezer 16 is inserted into the center of the mounting hole 42, so that the width of the upper gap 46 is equal to the width of the lower gap 48.

In the present embodiment, the radiation mask 30 is configured in a cylindrical shape as shown in one figure. Instead of this, the radiation mask 30 may be configured to have a cylindrical shape as a whole by a plurality of parts. These multiple parts can also be kept with each other It is equipped with a gap. For example, the radiation mask 30 can be divided into two parts in the axial direction. At this time, the upper portion of the radiation mask 30 is a tube whose both ends are open, and includes a first portion of the mask front end 28 and the mask side portion 36. The lower portion of the radiation mask 30 is open at the upper end and closed at the lower end, and has a second portion of the mask side portion 36 and a mask bottom portion 34. A gap extending in the circumferential direction is formed between the first portion and the second portion of the mask side portion 36. The mounting hole 42 of the refrigerator 16 has an upper portion formed in the first portion of the mask side portion 36, and a lower portion formed in the first portion of the mask side portion 36.

The cryopump 10 is provided with a refrigerator cover 70 that surrounds the second cylinder 25 of the refrigerator 16 . The refrigerator cover 70 is formed in a cylindrical shape having a diameter slightly larger than that of the second cylinder 25, and one end is attached to the second cooling stage 24, and extends through the mounting hole 42 of the radiation mask 30 toward the first cooling stage 22. A gap is provided between the refrigerator cover 70 and the radiation mask 30, and the refrigerator cover 70 is not in contact with the radiation mask 30. The refrigerator cover 70 is thermally connected to the second cooling stage 24, and is cooled to the same temperature as the second cooling stage 24. Therefore, the refrigerator cover 70 can also be regarded as a part of the second cryopanel 20.

The plate member 32 is an inlet cryopanel that is provided to the intake port 12 (or the cover opening 26, hereinafter the same) in order to protect the second cryopanel 20 from the radiant heat from the external heat source of the cryopump 10. The external heat source of the cryopump 10 is, for example, a heat source within the vacuum chamber in which the cryopump 10 is mounted. It not only limits the entry of radiant heat, but also limits the entry of gas molecules. The plate member 32 occupies a portion of the open area of the suction port 12 to limit the inflow of gas through the suction port 12 to the internal space 14 to a desired amount. The plate member 32 covers a large portion of the suction port 12. And, cooling of the plate member 32 The condensed gas (such as moisture) at the temperature captures its surface.

There is a slight gap in the axial direction between the mask front end 28 and the plate member 32. In order to cover the gap to restrict gas flow, the plate member 32 is provided with a skirt portion 33. The skirt 33 is a short cylinder that surrounds the plate member 32. The skirt portion 33 is formed integrally with the plate member 32 in a circular tray shape having the plate member 32 as a bottom surface. The circular tray configuration is configured to cover the radiation mask 30. Therefore, the skirt portion 33 projects downward from the plate member 32 in the axial direction and extends radially adjacent to the mask front end 28. The radial distance of the skirt 33 from the front end 28 of the mask is, for example, about the dimensional tolerance of the radiation mask 30.

The gap between the mask front end 28 and the plate member 32 may vary due to manufacturing errors. Such errors can be reduced by the processing and assembly of precision components, but it is not necessarily feasible to consider the increase in manufacturing costs thereby. The error relates to the individual difference of the cryopump 10. When the skirt portion 33 is absent, the amount of gas flowing into the inside of the radiation mask 30 changes depending on the size of the gap. The inflow amount of the gas is directly related to the exhaust speed of the cryopump 10. Regardless of whether the gap is too large or too small, the actual exhaust velocity deviates from the design performance. The skirt 33 covers the gap between the front end 28 of the mask and the plate member 32, thereby restricting the flow of gas through the gap and reducing the individual difference. As a result, it is also possible to reduce the individual difference of the cryopump exhaust speed with respect to the design performance.

The mask front end 28 and the plate member 32 are disposed above the suction port flange 40 of the cryopump housing 38 in the axial direction. As such, the radiation shield 30 extends toward the vacuum chamber in which the cryopump 10 is mounted. By extending the radiation mask 30 upward, the main accommodating space 21 of the condensing layer can be enlarged in the axial direction. Wherein the axial length of the extended portion is set to not be with the vacuum chamber (or true The gate valve between the cavity and the cryopump 10 interferes.

The cryopump housing 38 is a housing that houses the first cryopanel 18, the second cryopanel 20, and the cryopump 10 of the refrigerator 16, and is configured as a vacuum-tight vacuum container that holds the internal space 14. The suction port 12 is separated by the front end 39 of the cryopump housing 38. The cryopump housing 38 has an intake port flange 40 that extends radially outward from the front end 39. The suction port flange 40 is provided over the entire circumference of the cryopump housing 38. The cryopump 10 is mounted to the vacuum chamber using the suction port flange 40.

Fig. 3 is a plan view showing a plate member 32 according to the first embodiment of the present invention. In Fig. 3, representative constituent elements placed under the plate member 32 are indicated by broken lines.

The plate member 32 is provided with a flat plate (for example, a circular plate) that crosses the mask opening 26. The size (e.g., diameter) of the plate member 32 conforms to the size of the shroud opening 26. The plate member 32 is divided into a plate main body portion 50 and a plate outer edge portion 52. The outer edge portion 52 is for attaching the plate main body portion 50 to the edge portion of the radiation mask 30.

The plate member 32 is attached to the board mounting portion 29 of the mask front end 28. The plate attachment portion 29 is a convex portion that protrudes inward in the radial direction from the mask distal end 28, and is formed at equal intervals in the circumferential direction (for example, every 90 degrees). The plate member 32 is fixed to the board mounting portion 29 by an appropriate method. For example, the board mounting portion 29 and the board outer edge portion 52 have screw holes (not shown), and the board outer edge portion 52 is fastened to the board mounting portion 29 by bolts.

A plurality of small holes 54 that allow gas to flow are formed on the plate member 32. The small hole 54 is formed through the plate main body portion 50 and the outer edge portion 52 of the plate. hole. Therefore, the gas to be condensed on the second cryopanel 20 (mainly the top plate 60) can be received in the main accommodating space 21 between the plate member 32 and the second cryopanel 20 through the small holes 54. Further, a small hole 54 is not formed in the vicinity of the board mounting portion 29 in the outer edge portion 52 of the board.

The apertures 54 are regularly arranged. In the present embodiment, the small holes 54 are formed at equal intervals in the two orthogonal directions to form the lattice of the small holes 54. Alternatively, the small holes 54 may be equally spaced in the radial direction and the circumferential direction, respectively.

The shape of the small hole 54 is, for example, a circular shape, but is not limited thereto, and the small hole 54 may be an opening having a rectangular shape or the like, a slit extending in a straight line or a curved shape, or a notch formed on the outer circumference of the plate member 32. The aperture 54 is significantly smaller in size than the mask opening 26.

The plate main body portion 50 includes a gas passage region 56 having a plurality of small holes 54 and a gas isolation region 58 formed at a position different from the gas passage region 56 in the plate main body portion 50. Therefore, the board main body portion 50 is divided into a gas passage region 56 and a gas separation region 58. The gas passage region 56 and the gas isolation region 58 are adjacent to each other. Thus, the plate member 32 has a plurality of apertures 54 in a portion of its surface thereby forming a gas passage region 56. Further, a gas isolation region 58 is partially formed in the plate member 32.

In Fig. 3, the boundary between the gas passage region 56 and the gas isolation region 58 is indicated by a dashed line. In the present embodiment, the boundary between the gas passage region 56 and the gas separation region 58 is placed inside the boundary between the outer region 63 of the top plate 60 and the central region 62 (i.e., the step portion 65). As a result, the gas passage region 56 faces the outer region 63 of the top plate 60, and the gas The body isolation region 58 is opposite the central region 62 of the top plate 60.

As will be described later, the boundary between the gas passage region 56 and the gas separation region 58 is set to control the shape of the condensation layer 72 (see FIG. 4) which is grown on the top surface 61 of the top plate. Therefore, in order to grow the condensation layer 72 to a desired shape, the boundary of the gas passage region 56 and the gas isolation region 58 may be different from the illustration. The boundary may coincide with the boundary between the outer region 63 of the top plate 60 and the central region 62, or may be placed on the outside or intersected. Further, the shape of the boundary between the gas passage region 56 and the gas separation region 58 is not limited to a circular shape, and may be any other shape.

The gas isolation region 58 is formed by removing at least one small hole from the regular arrangement of the small holes 54. As shown in Fig. 3, the gas isolation region 58 is four small holes including a predetermined arrangement which is assumed to follow the small holes 54 in the gas passage region 56 (indicated by double dashed lines at the center of the plate main body portion 50) The area. Since no pores are provided in the gas isolation region 58, the gas isolation region 58 does not allow gas to pass.

At least one small hole may be provided in the gas isolation region 58. For example, all positions of the imaginary apertures indicated by dashed lines in the figure do not form apertures (i.e., the number of apertures 54 is reduced as compared to the regular arrangement in the gas passage region 56), thereby forming a gas barrier. Area 58. Alternatively, a hole smaller than the small hole 54 of the gas passage region 56 may be formed at the position of the imaginary orifice. The minute opening can be set to be the same number or less than the position of the imaginary aperture. Even so, the gas flow in the gas isolation region 58 can be limited as compared to the gas passage region 56.

Therefore, it is possible to form a small distribution in the gas passage region 56 with the first distribution. The holes do not form small holes in the gas isolation region 58 or form small holes in the second distribution different from the first distribution. The second distribution is set, for example, such that the opening area per unit area in the gas isolation region 58 is smaller than the opening area per unit area in the gas passage region 56. Here, the opening area refers to the total area of the small holes. Also, the first distribution may not have regularity. Therefore, the small holes 54 of the gas passage region 56 may be irregularly arranged.

Further, the total area of the openings of the plate member 32 is determined in design, for example, in accordance with the required performance such as the exhaust speed. Therefore, whenever the small holes are removed or reduced in order to set the gas isolation region 58, it is preferable to compensate for the reduction in the area of the opening thus produced. For this purpose, a new small hole 54 may be added to the gas passage region 56, or the existing small hole 54 may be enlarged. It is also possible to change the position of the existing aperture 54.

The operation performed by the cryopump 10 having the above configuration will be described below. When the cryopump 10 is operated, first, the inside of the vacuum chamber is roughly drawn to, for example, about 1 Pa by another appropriate rough pump before the operation. Thereafter, the cryopump 10 is operated. The first cooling stage 22 and the second cooling stage 24 are cooled by the driving of the refrigerator 16, and the first low temperature plate 18 and the second low temperature plate 20 that are thermally connected are also cooled. Each of the first cryopanel 18 and the second cryopanel 20 is cooled to a first temperature and a second temperature lower than the first temperature.

The plate member 32 cools the gas molecules that have flown from the vacuum chamber toward the inside of the cryopump 10, and condenses a gas (for example, moisture or the like) whose vapor enthalpy is sufficiently reduced at the cooling temperature to condense on the surface to be exhausted. The gas whose vapor enthalpy is not sufficiently reduced at the cooling temperature of the plate member 32 enters the main accommodating space 21 through the plurality of small holes 54. Alternatively, a portion of the gas is trapped by the gas barrier of the plate member 32. The field 58 reflects but does not enter the main accommodation space 21.

A gas (for example, argon or the like) whose vapor enthalpy is sufficiently reduced at the cooling temperature of the second cryopanel 20 in the gas molecules that have entered is condensed on the surface of the second cryopanel 20 (mainly the top surface 61 of the top plate) to be exhausted. Even if the vapor enthalpy is not sufficiently reduced at the cooling temperature (for example, hydrogen or the like), it is adhered to the surface of the second cryopanel 20 and adsorbed by the cooled adsorbent 68 to be exhausted. In this way, the cryopump 10 is capable of bringing the vacuum of the vacuum chamber to a desired level.

Fig. 4 is a view showing the cryopump 10 during the exhaust operation. As shown in Fig. 4, ice or frost formed by the condensed gas is deposited on the top plate 60 of the cryopump 10. The main component of the condensation layer 72 is, for example, argon. The ice layer grows with the exhaust gas running time, so that the thickness gradually increases. In addition, in FIG. 4, for the sake of simplicity, the condensation layer deposited on the conventional plate 67 and the refrigerating machine cover 70 is omitted.

When the plate member 32 does not have the gas isolation region 58 (that is, when the plate member 32 has the double-dotted hole shown in FIG. 3), as shown by the broken line in FIG. 4, the dome type or the mushroom type The condensation layer grows on the top plate 60. When a plurality of small holes 54 are evenly distributed on the plate member 32, the gas easily flows into the central portion of the main accommodation space 21. Therefore, as shown in the figure, it is easy to cause condensation to concentrate on the center portion. Further, in order to reduce the number of the small holes 54 of the outer edge portion 52 of the plate for the mounting of the plate member 32, it is also possible that condensation is concentrated at the center portion.

If the dome-shaped condensation layer is further grown in the radial direction, the outer peripheral portion of the condensation layer may come into contact with the mask side portion 36. If the mount 37 and the top plate The gap between 60 is narrow and the condensation layer first comes into contact with the mount 37. At the contact portion, the gas is again vaporized and released to the outside of the main accommodating space 21 and the cryopump 10. Therefore, in the future, the cryopump 10 cannot provide design exhaust performance. Therefore, the amount of gas stored at this time is given to the maximum storage amount of the cryopump 10. Part of the condensation layer (at this time, the condensation layer near the mount 37) determines the gas storage limit of the cryopump 10.

Cryopumps are generally designed to be axisymmetric. However, the horizontal cryopump 10 is a horizontally disposed freezer 16 and therefore necessarily has an asymmetrical portion (e.g., mount 37). In the present embodiment, the shape of the top plate 60 and the asymmetrical portion are fitted in the circumferential direction to align the width of the gap between the top plate 60 and the radiation mask 30. It is possible to prevent the condensation layer which is radially grown on the top plate 60 from contacting only the specific portion (in this case, the condensation layer in the vicinity of the mount 37) with the radiation mask 30. As a result, according to this embodiment, the amount of gas stored in the cryopump 10 can be increased.

Further, if the dome-shaped condensing layer is further grown in the axial direction, the top portion of the condensing layer near the center axis A may come into contact with the lower surface of the plate member 32. The amount of gas stored at this time is given to the maximum storage amount of the cryopump 10. The portion of the condensing layer (at this time, the top of the condensing layer near the central axis A) determines the gas storage limit of the cryopump 10.

When the plate member 32 has the gas isolation region 58 (that is, when the plate member 32 does not have the double-dotted hole shown in FIG. 2), as shown by the solid line in FIG. 4, the cylindrical condensation layer 72 is The top plate 60 grows. The gas isolation region 58 restricts the flow of gas into the central portion of the main accommodating space 21, so that the condensation can be concentrated at the center portion. The result, as shown by the arrow D in the figure As shown, the cylindrical condensation layer 72 has a height at which the condensation layer near the central axis A becomes smaller than the dome-shaped condensation layer. On the other hand, as indicated by an arrow E in the figure, the height of the condensation layer in the outer peripheral portion becomes larger than that in the dome-shaped condensation layer.

As described above, according to the present embodiment, the height distribution of the upper surface of the condensation layer which is grown on the top surface 61 of the top plate can be made uniform. The accommodation efficiency of the condensation layer 72 in the main accommodation space 21 is improved by making the shape of the condensation layer 72 coincide with the main accommodation space 21. In this way, the amount of gas stored in the cryopump 10 can be increased.

Fig. 5 is a side cross-sectional view showing the main part of the cryopump 10 according to the second embodiment of the present invention. The cryopump 10 of the second embodiment has an arrangement different from that of the first embodiment in the second cryopanel 20 . Regarding the other parts, the second embodiment is the same as the first embodiment. In the following description, the same portions are appropriately omitted in order to avoid redundancy.

As shown in FIG. 5, the arrangement of the second cryopanel 20 is adjusted such that the width of the side gap 43 coincides with the width of the gap portion 44. As indicated by an arrow F in the figure, the second cryopanel 20 is disposed to be displaced from the central axis A by the center of the second cryopanel 20 so that the second cryopanel 20 is separated from the mount 37. The second cryopanel 20 is eccentric from the center line A so as to be away from the high temperature side of the refrigerator 16. In this manner, the side gap 43 is enlarged, and the gap portion 44 is narrowed on the opposite side via the central axis A. In the second embodiment, the top plate 60 does not have the notch portion 74. Even in the same manner as in the first embodiment, the width of the gap surrounding the side surface of the condensation layer in which the top plate 60 grows can be made uniform. Further, in an embodiment, the top plate 60 may have a notch portion 74, and the second cryopanel 20 may be eccentrically disposed.

Fig. 6 is a side cross-sectional view showing the main part of the cryopump 10 according to the third embodiment of the present invention. The cryopump 10 of the third embodiment has an arrangement in which the refrigerator 16 has a different embodiment from the above-described embodiment. Regarding the other parts, the third embodiment is the same as the embodiment described above. In the following description, the same portions are appropriately omitted in order to avoid redundancy.

As shown in Fig. 6, the refrigerator 16 is disposed such that the width G1 of the upper gap 46 is wider than the width G2 of the lower gap 48. Thereby, the space between the refrigerator cover 70 and the radiation mask 30 can be enlarged. By enlarging the upper gap 46 close to the main accommodation space 21, more condensation layers can be accommodated. Further, since the entire second cryopanel 20 is moved downward, the main accommodating space 21 can be enlarged in the axial direction as compared with the above-described embodiment. In this way, the amount of gas stored in the cryopump 10 can be increased.

As described above, according to the embodiment of the present invention, the shape or arrangement of the top plate 60 is set such that the gap between the radiation mask 30 and the top plate 60 is substantially uniform. Thereby, it is possible to suppress condensation on the condensation layer deposited on the top plate 60 to concentrate on a specific portion. Thereby, the accommodation efficiency of the condensation layer in the main accommodation space 21 can be improved, and the gas storage amount of the cryopump 10 can be improved.

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 design changes can be made and various modifications can be made, and such modifications are also included in the scope of the present invention.

For example, the configuration described in any one of the first embodiment to the third embodiment and the first to third embodiments can be performed. The cryopump 10 is configured by a combination of the configurations described in the other embodiments.

Further, the cryopump 10 may include an inlet cryopanel disposed in the mask opening 26 instead of the plate member 32. The inlet cryopanel may have, for example, one or a plurality of flat plates (for example, a circular plate) type plate, or may have a louver or a zigzag shape formed in a concentric or lattice shape. The gas passage region 56 and the gas isolation region 58 may be formed in the mask opening 26 by adjusting the shape, arrangement or spacing of the louver or sawtooth shaped louver.

In the above embodiment, the plate member 32 is divided into two regions, that is, a gas passage region 56 and a gas isolation region 58. However, the plate member 32 may have three or more regions. In the plate member 32, as the third region, a region through which the gas can pass more easily than the gas passage region 56 can be formed, and a region in which the gas is less likely to pass through the gas isolation region 58 can be formed.

Embodiments of the present invention can also be expressed as follows.

A cryopump comprising: a first cooling stage; and a second cooling stage cooled to a temperature lower than the first cooling stage; and the first cryopanel having a radiation shielding of the main opening a cover member and a plate member transversely intersecting the main opening, and being thermally connected to the first cooling stage; and a second low temperature plate surrounded by the first low temperature plate and thermally connected to the second cooling stage, wherein the plate member is provided with a plate a main body portion for mounting the plate main body portion on an outer edge portion of the radiation mask, The plate main body portion includes a gas passage region having a plurality of small holes through which the gas condensed in the second low temperature plate passes, and a gas isolation region formed in the plate main body portion different from the gas passage region position.

2. The cryopump according to the first aspect, wherein the second cryopanel has a front surface facing the plate main body portion, the front surface includes a central region, and an outer region surrounding the central region, the gas passage region and the The outer regions are opposed to each other, and the gas isolation regions are opposed to the central regions.

3. The cryopump according to the first or second aspect, wherein the radiation mask includes a side portion surrounding the second cryopanel, and a gap having a narrow portion is formed between the side portion and the second cryopanel, The gas isolation region is formed at a position corresponding to the narrow portion.

4. The cryopump according to any one of the first to third aspect, wherein the radiation mask includes a mounting seat located on a side of the second cryopanel and configured to mount the refrigerator to the radiation a mask; and an annular portion adjacent to the mounting seat and surrounding the second cryopanel, wherein a side gap is formed between the second cryopanel and the mount, and the second cryopanel and the ring are formed An annular gap continuous with the side gap is formed between the portions, and the shape or arrangement of the second cryopanel is adjusted such that the width of the side gap matches the width of the annular gap.

5. The cryopump according to the fourth aspect, wherein the second cryopanel has a notch portion that expands a width of the side gap.

6. The cryopump according to the fourth or fifth aspect, wherein the second cryopanel is disposed to be offset from a center of the second cryopanel from an axis passing through the main opening, so that the second cryopanel and the mounting are performed Separate.

The cryopump according to any one of the first to sixth aspect, wherein the radiation mask is provided with a mounting hole for the refrigerator, and the refrigerator includes a first cooling stage and the second cooling. a connecting portion of the table, the connecting portion is inserted into the mounting hole, and an upper gap is formed between the connecting portion and the mounting hole on a side close to the main opening, and a side away from the main opening is formed In the lower gap, the width of the aforementioned upper gap is wider than the width of the lower gap.

A vacuum evacuation method using a cryopump, the method comprising the steps of: cooling a plate member and a second cryopanel to a first temperature and a second temperature lower than the second temperature; and forming the surface of the plate member a plurality of small holes for receiving gas between the plate member and the second cryopanel; and condensing the gas on the second cryopanel, the cryopump having the plate member having a main opening transversely And the second low temperature plate facing the plate member.

A cryopump comprising: a first cryopanel having a radiation mask having a main opening; and a plate member transversely intersecting the main opening; and a second cryopanel having a front surface facing the plate member and being cooled The forming temperature is lower than the first low temperature plate, and the front surface includes a central region and an outer region surrounding the central region, and the plate member includes a gas passage region and has a plurality of gases for condensing the gas in the second cryopanel a small hole and facing the outer region; and a gas isolation region facing the central region.

A cryopump comprising: a first cryopanel having a radiation mask having a main opening; and an inlet cryopanel disposed in the main opening; and a second cryopanel surrounded by the first cryopanel and cooled The temperature is lower than the first low temperature plate, and the radiation mask includes a side portion surrounding the second low temperature plate, and a gap having a narrow portion is formed between the side portion and the second low temperature plate, and the inlet cryopanel is The position corresponding to the narrow portion has a gas isolation region.

A cryopump comprising: a first cooling stage; and a second cooling stage cooled to a temperature lower than the first cooling stage; and a first cryopanel having a radiation mask and a main opening An inlet cryopanel of the main opening, and is thermally connected to the first cooling stage; and The second cryopanel is surrounded by the first cryopanel and is thermally connected to the second cooling stage. The radiation mask includes a mounting seat located on a side of the second cryopanel and is used to mount the refrigerator. And the mask portion is adjacent to the mounting seat and surrounding the second cryopanel, and a side gap is formed between the second cryopanel and the mount, and the second low temperature is formed A gap portion continuous with the side gap is formed between the plate and the mask portion, and the shape or arrangement of the second low temperature plate is adjusted such that the width of the side gap matches the width of the gap portion.

12. The cryopump according to the eleventh aspect, wherein the second cryopanel has a notch portion that expands a width of the side gap.

The cryopump according to the eleventh or 12th aspect, wherein the second cryopanel is disposed to be offset from a center of the second cryopanel from an axis passing through the main opening to allow the second cryopanel to be mounted Separate.

The cryopump according to any one of the embodiments of the present invention, wherein the second cryopanel has a front surface facing the inlet cryopanel, and the front surface includes a central region and an outer region surrounding the central region The inlet cryopanel is provided with a gas passage region and a gas isolation region for allowing a gas condensed in the second cryopanel to pass therethrough, and the gas passes through The region faces the outer region, and the gas isolation region faces the center region.

15. The cryopump according to the fourteenth aspect, wherein the gas passage region is provided with a plate portion having a plurality of small holes.

The cryopump according to any one of the embodiments of the present invention, wherein the radiation mask is provided with a mounting hole for the refrigerator, and the refrigerator includes a first cooling stage and the second cooling a connecting portion of the table, the connecting portion is inserted into the mounting hole, and an upper gap is formed between the connecting portion and the mounting hole on a side close to the main opening, and is formed away from the main opening side There is a lower gap, and the width of the aforementioned upper gap is wider than the width of the aforementioned lower gap.

10‧‧‧Cryogenic pump

12‧‧‧ suction port

14‧‧‧Internal space

16‧‧‧Freezer

18‧‧‧1st cryogenic plate

20‧‧‧2nd cryogenic plate

21‧‧‧Main accommodation space

22‧‧‧1st cooling station

23‧‧‧1st cylinder

24‧‧‧2nd cooling station

25‧‧‧2nd cylinder

26‧‧‧Mask opening

28‧‧‧mask front end

30‧‧‧radiation mask

32‧‧‧ Board components

33‧‧‧ skirt

34‧‧‧Bottom of the mask

36‧‧‧Mask side

37‧‧‧ Mounting

38‧‧‧Cryogenic pump container

39‧‧‧ front end

40‧‧‧ suction port flange

42‧‧‧Mounting holes

43‧‧‧ side clearance

44‧‧‧Gap section

45‧‧‧heat transfer member

46‧‧‧Over the gap

48‧‧‧The gap below

50‧‧‧ board main body

56‧‧‧Gas passage area

58‧‧‧Gas isolation zone

60‧‧‧ top board

61‧‧‧ Top surface of the top plate

62‧‧‧Central area

63‧‧‧Outer area

64‧‧‧Fixed components

65‧‧‧Steps

66‧‧‧ peripheral end

67‧‧‧General Board

68‧‧‧Adsorbent

70‧‧‧Freezer cover

A‧‧‧ center axis

Claims (6)

A cryopump including a first cooling stage and a second cooling stage cooled to a temperature lower than the first cooling stage, and a first cryopanel having a radiation mask having a main opening and An inlet cryopanel disposed in the main opening and thermally connected to the first cooling stage; and a second cryopanel having a top plate facing the inlet cryopanel and a conventional plate disposed below the top plate, The first cryopanel is surrounded by the second cooling stage, and the radiation mask includes a mounting seat on a side of the top plate, and the refrigerator is mounted on the radiation mask; and the mask a portion adjacent to the mounting seat and surrounding the top plate in a circumferential direction, a side gap is formed between the top plate and the mounting seat, and a side gap is formed between the top plate and the mask portion In the continuous gap portion, the shape or arrangement of the top plate is adjusted such that the width of the side gap matches the width of the gap portion, and the mount is recessed when viewed from the outside of the radiation mask. Said mask portion is formed with the freezer for mounting on a flat portion of the radiation shield. The cryopump according to claim 1, wherein the top plate has a notch portion that widens the width of the side gap. A cryopump according to claim 1 or 2, wherein The aforementioned top plate is configured to be offset from the center of the aforementioned top plate from the axis passing through the aforementioned main opening to separate the aforementioned top plate from the aforementioned mounting seat. The cryopump according to claim 1 or 2, wherein the top plate includes a front surface facing the inlet cryopanel, the front surface includes a central region and an outer region surrounding the central region, and the inlet cryopanel is provided The gas passage region and the gas isolation region are configured to pass the gas condensed on the top plate, and the gas passage region faces the outer region, and the gas isolation region faces the center region. The cryopump according to the fourth aspect of the invention, wherein the gas passage region has a plate portion having a plurality of small holes. The cryopump according to the first or second aspect of the invention, wherein the radiation mask is provided with a mounting hole for the refrigerator, and the refrigerator includes a connecting portion that connects the first cooling stage and the second cooling stage. The connecting portion is inserted into the mounting hole, and an upper gap is formed between the connecting portion and the mounting hole on a side closer to the main opening, and a lower gap is formed on a side away from the main opening. The width of the upper gap is wider than the width of the aforementioned lower gap.