Electrostatic chuck

Abstract

To provide an electrostatic chuck which can reduce the fluctuation in the in-plane temperature distribution of a substrate during a process even with a configuration in which an outer circumferential edge of a dielectric substrate protrudes.SOLUTION: An electrostatic chuck 10 includes a dielectric substrate 100, an attraction electrode 130 provided inside the dielectric substrate 100, and a base plate 200 joined to the dielectric substrate 100. In top view, the dielectric substrate 100 includes a protrusion section 101 which protrudes outward from a surface to be joined of the base plate 200, and a part of the attraction electrode 130 is provided in the protrusion section 101.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electrostatic chuck. [Background technology]

[0002] Semiconductor manufacturing equipment, such as an etching apparatus, is equipped with an electrostatic chuck as a device for attracting and holding a substrate, such as a silicon wafer, to be processed. The electrostatic chuck includes a dielectric substrate provided with an attracting electrode and a base plate supporting the dielectric substrate, which are joined together. When a voltage is applied to the attracting electrode, an electrostatic force is generated, attracting and holding a substrate placed on the dielectric substrate. The attracting electrode may be formed on the surface of the dielectric substrate facing the base plate, but is often provided inside the dielectric substrate, as described in Patent Document 1 below, for example. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-119654 Summary of the Invention [Problem to be solved by the invention]

[0004] The bonding layer between the dielectric substrate and the base plate is made of, for example, a hardened silicone adhesive. During processing such as etching, the edge of the bonding layer may be exposed to plasma, deteriorate, and fly off, adversely affecting the substrate being processed.

[0005] To prevent this, the inventors have developed an electrostatic chuck in which the dielectric substrate is larger than the bonded surface of the base plate, i.e., the outer edge of the dielectric substrate protrudes outward from the bonded surface. This configuration allows a member covering the periphery of the bonding layer to be positioned below the dielectric substrate. This reduces the influence of the bonding layer on the substrate during processing.

[0006] However, when the outer peripheral edge of the dielectric substrate is protruded as described above, there is a possibility that the protrusion will not be cooled sufficiently because there is no base plate directly below the protrusion, which may result in a large variation in the temperature distribution within the surface of the substrate during processing.

[0007] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an electrostatic chuck that can suppress variations in the in-plane temperature distribution of a substrate during processing, even when the outer peripheral end of the dielectric substrate is configured to protrude. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides an electrostatic chuck including a dielectric substrate having a mounting surface on which an object to be attracted is placed, an attraction electrode provided inside the dielectric substrate, and a base plate joined to the dielectric substrate, wherein, when viewed from a direction perpendicular to the mounting surface, the dielectric substrate has a protruding portion that protrudes outward beyond the joined surface of the base plate, and a part of the attraction electrode is provided on the protruding portion.

[0009] By providing a portion of the chucking electrode on the protrusion, the chucking force of the protrusion to the substrate is increased, and the two are tightly attached to each other. This reduces the thermal resistance between the protrusion and the substrate, making it possible to suppress temperature increases in the area of the substrate directly above the protrusion. As a result, it is possible to suppress variations in the temperature distribution within the surface of the substrate during processing compared to conventional methods. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an electrostatic chuck that can suppress variations in the in-plane temperature distribution of a substrate during processing, even when the outer peripheral end of the dielectric substrate is configured to protrude. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view schematically showing the configuration of an electrostatic chuck according to a first embodiment. [Figure 2] FIG. 2 is an enlarged view showing a part of the configuration of FIG. 1 in detail. [Figure 3] 3A and 3B are diagrams illustrating a configuration of a coolant flow path formed in a base plate of the first embodiment. [Figure 4] FIG. 10 is a cross-sectional view schematically showing the configuration of an electrostatic chuck according to a second embodiment. [Figure 5] 10A and 10B are diagrams illustrating the configuration of a coolant flow path formed in a base plate according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

[0013] A first embodiment will be described. An electrostatic chuck 10 according to this embodiment is configured to electrostatically attract and hold a substrate W to be processed inside a semiconductor manufacturing apparatus (not shown), such as an etching apparatus. The object to be attracted, that is, the substrate W, is, for example, a silicon wafer. The electrostatic chuck 10 may also be used in apparatuses other than semiconductor manufacturing apparatuses.

[0014] 1 is a schematic cross-sectional view showing the configuration of an electrostatic chuck 10 in a state where the electrostatic chuck 10 attracts and holds a substrate W. The electrostatic chuck 10 includes a dielectric substrate 100 and a base plate 200.

[0015] The dielectric substrate 100 is a substantially disk-shaped member made of a sintered ceramic body. The dielectric substrate 100 contains, for example, high-purity aluminum oxide (Al2O3), but may also contain other materials. The purity, type, and additives of the ceramics in the dielectric substrate 100 can be appropriately set taking into consideration the plasma resistance and other properties required of the dielectric substrate 100 in semiconductor manufacturing equipment. The diameter of the dielectric substrate 100 is, for example, 290 to 300 mm. The thickness of the dielectric substrate 100 is, for example, 0.5 to 3.0 mm.

[0016] 1 of the dielectric substrate 100 is a "mounting surface" on which the substrate W is placed. Also, a lower surface 120 of the dielectric substrate 100 in FIG. 1 is a "bonded surface" that is bonded to the base plate 200 via a bonding layer 300. The viewpoint when the electrostatic chuck 10 is viewed from the side of the surface 110 along a direction perpendicular to the surface 110 will hereinafter also be referred to as a "top view."

[0017] An adsorption electrode 130 is embedded within the dielectric substrate 100. The adsorption electrode 130 is a thin, flat layer made of a metal material such as tungsten, and is disposed parallel to the surface 110. The adsorption electrode 130 may be made of tungsten or other materials such as molybdenum, platinum, or palladium. When a voltage is applied to the adsorption electrode 130 from the outside via a power supply line (not shown), an electrostatic force is generated between the surface 110 and the substrate W, thereby adsorbing and holding the substrate W. Various known configurations can be employed for the power supply line. As in this embodiment, only one adsorption electrode 130 may be provided as a so-called "monopolar" electrode, or two may be provided as so-called "bipolar" electrodes. The depth at which the adsorption electrode 130 is disposed, i.e., the distance from a bottom surface 116 (described below) to the adsorption electrode 130, is, for example, 0.1 to 0.5 mm.

[0018] In addition to the above-described attracting electrode 130, an RF electrode 140 is also embedded inside the dielectric substrate 100. The RF electrode 140 is provided as one of a pair of opposing electrodes for generating plasma in the semiconductor manufacturing equipment. The other opposing electrode is provided at a position above the electrostatic chuck 10 in the semiconductor manufacturing equipment. When a high-frequency AC voltage is applied between these opposing electrodes, plasma is generated above the substrate W, and is used for processing the substrate W, such as film formation and etching.

[0019] Like the chucking electrode 130, the RF electrode 140 is a thin, flat layer made of a metal material such as tungsten. Other materials that may be used for the RF electrode 140 include molybdenum, platinum, and palladium, in addition to tungsten. The RF electrode 140 is embedded in a position closer to the surface 120 than the chucking electrode 130. Like the chucking electrode 130, the RF electrode 140 is disposed parallel to the surface 110. The RF electrode 140 is a single electrode that is substantially circular in top view. The center of the RF electrode 140 coincides with the center of the dielectric substrate 100 in top view. The distance from the chucking electrode 130 to the RF electrode 140 is, for example, 0.2 to 2 mm. The distance from the RF electrode 140 to the surface 120 is, for example, 0.1 to 2.5 mm.

[0020] As shown in Fig. 1, a space SP is formed between the dielectric substrate 100 and the substrate W. When a process such as etching is performed in the semiconductor manufacturing equipment, helium gas for temperature adjustment is supplied to the space SP from the outside through a gas hole (not shown). By providing helium gas between the dielectric substrate 100 and the substrate W, the thermal resistance between them is adjusted, thereby maintaining the temperature of the substrate W at an appropriate temperature. Note that the temperature adjustment gas supplied to the space SP may be a gas other than helium.

[0021] A seal ring 111 and dots 112 are provided on a surface 110 that is a mounting surface, and the space SP is formed around these.

[0022] The seal ring 111 is a wall that partitions the space SP at the outermost position. The seal ring 111 is an annular protrusion formed on the surface 110. The tip (the upper end in FIG. 1) of the seal ring 111 is part of the surface 110 and abuts against the substrate W. The tip of the seal ring 111 can be said to be the outermost part of the surface 110, which is the mounting surface.

[0023] It should be noted that a plurality of seal rings 111 may be provided to divide the space SP. With such a configuration, the pressure of the helium gas in each space SP can be adjusted individually, and the surface temperature distribution of the substrate W during processing can be made more uniform.

[0024] 1, the portion marked with the reference numeral "116" is the bottom surface of the space SP. Hereinafter, this portion will also be referred to as the "bottom surface 116." The seal ring 111, together with the dots 112 described below, is formed by digging down a portion of the surface 110 to the position of the bottom surface 116.

[0025] The dots 112 are circular protrusions that protrude from the bottom surface 116. A plurality of dots 112 are provided, and are distributed approximately evenly on the mounting surface of the dielectric substrate 100. The tip of each dot 112 forms part of the surface 110 and comes into contact with the substrate W. By providing a plurality of such dots 112, bending of the substrate W is suppressed.

[0026] The base plate 200 is a substantially disk-shaped member that supports the dielectric substrate 100. The base plate 200 is formed of a metal material such as aluminum. The base plate 200 is bonded to the surface 120 of the dielectric substrate 100 via a bonding layer 300. The surface 210 of the base plate 200, which is on the upper side in FIG. 1, is the "bonded surface" that is bonded to the dielectric substrate 100.

[0027] The bonding layer 300 is a layer provided between the dielectric substrate 100 and the base plate 200, and bonds them together. The bonding layer 300 is formed by curing an adhesive made of an insulating material. In this embodiment, a silicone adhesive is used as the adhesive. However, the bonding layer 300 may be formed by curing another type of adhesive. In either case, it is preferable to use a material with as high a thermal conductivity as possible as the material for the bonding layer 300 so as to reduce the thermal resistance between the dielectric substrate 100 and the base plate 200.

[0028] An insulating film may be formed on the surface of the base plate 200. For example, an alumina film formed by thermal spraying can be used as the insulating film. By covering the surface of the base plate 200 with an insulating film, the dielectric strength of the base plate 200 can be increased. The thickness of the insulating film is, for example, 1 mm or less.

[0029] The base plate 200 has a support portion 201 and a flange portion 202. The support portion 201 is the upper portion of the base plate 200 in FIG. 1 and is a generally cylindrical portion that directly supports the dielectric substrate 100 from below. The diameter of the support portion 201, i.e., the diameter of the surface 210, is, for example, 290 to 300 mm, similar to that of the dielectric substrate 100, but is slightly smaller than the diameter of the dielectric substrate 100. The thickness of the support portion 201, i.e., the amount by which the support portion 201 protrudes upward in FIG. 1 (the amount by which it protrudes from the flange portion 202), is, for example, 3 to 15 mm.

[0030] The flange 202 is the lower part of the base plate 200 in FIG. 1. The flange 202 is substantially cylindrical, and its central axis coincides with the central axis of the support portion 201. The diameter of the flange 202 is larger than the diameter of the support portion 201. The amount of protrusion of the flange 202 from the outer surface of the support portion 201 (i.e., the amount of protrusion in the radial direction) is, for example, 20 to 30 mm. The thickness of the flange 202 is, for example, 25 to 40 mm. The overall thickness of the base plate 200, including the support portion 201 and the flange 202, is, for example, 30 to 40 mm.

[0031] When processing a substrate W in a semiconductor manufacturing apparatus, a focus ring (not shown) is installed on the upper surface 203 of the flange portion 202. The focus ring is an annular, plate-shaped member made of an insulating material such as quartz, and is installed for the purpose of adjusting the distribution of plasma during processing. The dielectric substrate 100 and the support portion 201 are substantially entirely surrounded by the focus ring from the outer periphery.

[0032] A coolant flow path 250 for passing a coolant is formed inside the base plate 200. When a process such as etching is performed in the semiconductor manufacturing equipment, a coolant is supplied to the coolant flow path 250 from the outside, thereby cooling the base plate 200. Heat generated in the substrate W during the process is transferred to the coolant via the helium gas in the space SP, the dielectric substrate 100, and the base plate 200, and is discharged to the outside together with the coolant. The coolant is supplied to and discharged from the coolant flow path 250 through openings 255 and 256 (not shown in FIG. 1, see FIG. 3) formed on the surface 220 of the base plate 200 opposite the surface 210. The specific configuration of the coolant flow path 250 will be described later.

[0033] As described above, in the electrostatic chuck 10 according to this embodiment, the diameter of the support portion 201, which is the portion of the base plate 200 that directly supports the dielectric substrate 100, is smaller than the diameter of the dielectric substrate 100. As a result, the dielectric substrate 100 protrudes outward from the surface 210, which is the surface to be joined. Such a protruding portion of the dielectric substrate 100 will also be referred to as the "protruding portion 101" hereinafter. The protruding amount of the protruding portion 101, i.e., the protruding amount of the dielectric substrate 100 from the outer surface of the support portion 201 (protruding amount in the radial direction), is, for example, 1 mm to 3 mm.

[0034] During processing such as etching, the end of the bonding layer 300 may be exposed to plasma, deteriorate, and fly off, which may adversely affect the substrate W during processing. When the protrusion 101 is provided on the dielectric substrate 100 as in this embodiment, a member that covers the exposed portion of the bonding layer 300 from the periphery can be disposed below the dielectric substrate 100. In FIG. 2, an example of the location of such a member is indicated by a dashed line labeled "400." By disposing this member, the influence of the bonding layer 300 on the substrate W during processing can be suppressed.

[0035] Incidentally, it is known that during processing such as etching, the temperature of the substrate W tends to rise, particularly at the outer periphery. Furthermore, when the protruding portion 101 is provided on the dielectric substrate 100 as in this embodiment, the base plate 200 is not present directly below the protruding portion 101, and therefore the protruding portion 101 may not be sufficiently cooled. As a result, the temperature of the substrate W, particularly at the outer periphery, may rise further, and the in-plane temperature distribution of the substrate W may vary more during processing.

[0036] Therefore, in the electrostatic chuck 10 of this embodiment, various improvements described below have been made to suppress the above-mentioned local temperature rise and to make the in-plane temperature distribution of the substrate W during processing as uniform as possible.

[0037] 2 is an enlarged detailed view of the configuration of the protrusion 101 and its vicinity of the electrostatic chuck 10 of FIG. 1. The dotted line DL1 shown in FIG. 2 indicates the position of the outer peripheral end of the attraction electrode 130. The dotted line DL2 indicates the position of the outer peripheral end of the surface 210. In this embodiment, the diameter of the surface 210 and the diameter of the outer peripheral end of the RF electrode 140 are equal to each other. Therefore, the dotted line DL2 also indicates the position of the outer peripheral end of the RF electrode 140.

[0038] The "outer peripheral end" of the chucking electrode 130 refers to the portion where the chucking electrode 130 overlaps with the smallest circle among the circles that encompass the entire chucking electrode 130 in a top view. The "outer peripheral end" of the RF electrode 140 is defined similarly. The diameter of the surface 210 and the diameter of the outer peripheral end of the RF electrode 140 may be the same as described above, but may also be different from each other.

[0039] The diameter of the outer peripheral end of the chucking electrode 130 is larger than the diameter of the surface 210 of the base plate 200. Therefore, the outer peripheral end (dotted line DL1) of the chucking electrode 130 extends into the inside of the protruding portion 101 of the dielectric substrate 100.

[0040] In this manner, in a configuration in which a part of the chucking electrode 130 is provided on the protrusion 101, the chucking force of the protrusion 101 to the substrate W increases, and the two are brought into close contact with each other with a strong force. This reduces the thermal resistance between the protrusion 101 and the substrate W, making it possible to suppress a rise in the temperature of the substrate W directly above the protrusion 101. As a result, it is possible to suppress variations in the in-plane temperature distribution of the substrate W during processing compared to conventional methods.

[0041] The diameter of the outer peripheral end of the chucking electrode 130 is larger than the diameter of the inner peripheral side of the seal ring 111 and smaller than the diameter of the outer peripheral side of the seal ring 111. Furthermore, the diameter of the outer peripheral side of the seal ring 111 is larger than the diameter of the surface 210 of the base plate 200. In top view, a portion of the seal ring 111 overlaps with both the protrusion 101 and the chucking electrode 130. By overlapping the seal ring 111, the protrusion 101, and the chucking electrode 130 in top view, cooling of the substrate W in this portion can be further enhanced. As a result, variation in the in-plane temperature distribution of the substrate W can be further suppressed.

[0042] The entire seal ring 111, rather than just a part of it, may overlap both the protrusion 101 and the chucking electrode 130 in top view. In this case, the diameter of the inner periphery of the seal ring 111 may be made larger than the diameter of the support portion 201. The diameter of the outer periphery of the seal ring 111 may be made smaller than the diameter of the dielectric substrate 100 and also smaller than the diameter of the outer periphery end of the chucking electrode 130.

[0043] In either case, it is preferable to ensure a distance of approximately 0.1 mm to 3 mm from the outer peripheral end (dotted line DL1) of the chucking electrode 130 to the outer surface of the dielectric substrate 100. By ensuring such a distance, it is possible to prevent dielectric breakdown between the chucking electrode 130 and the outside.

[0044] The diameter of the outer peripheral end (dotted line DL2) of the RF electrode 140 is preferably equal to or smaller than the diameter of the outer peripheral end (dotted line DL1) of the chucking electrode 130. In other words, the RF electrode 140 is preferably provided in a range such that its outer peripheral end does not extend beyond the outer peripheral end of the chucking electrode 130 in a top view. The distance from the outer peripheral end (dotted line DL2) of the RF electrode 140 to the outer surface of the dielectric substrate 100 is preferably set to approximately 0.1 mm to 5 mm.

[0045] When the substrate W is being processed, Joule heat is generated in the RF electrode 140, which may increase the temperature of surrounding components. In other words, the RF electrode 140 can become a heat source during processing. Therefore, in this embodiment, as described above, the RF electrode 140 is provided within a range in which its outer circumferential edge does not extend beyond the outer circumferential edge of the attraction electrode 130. By keeping the RF electrode 140, which is a heat source, within the above range, it is possible to further suppress the temperature increase in the outer circumferential portion of the substrate W.

[0046] For ease of explanation, the outer peripheral edge of surface 110, which is the mounting surface, will hereinafter also be referred to as "edge E." Edge E has a circular ridgeline when viewed from above, but a portion of the ridgeline (for example, the orientation flat portion) may be a ridgeline that is not circular.

[0047] A portion of the base plate 200 that overlaps with the end E in a top view is also referred to below as a "first portion P1." The first portion P1 is, for example, a portion that has a certain width that encompasses the entire end E in a top view, but the method for determining the width is not particularly limited.

[0048] A portion of the base plate 200 that is further outwardly disposed than the first portion P1 in a top view is hereinafter also referred to as a "second portion P2." The second portion P2 refers to the entire portion of the base plate 200 that is adjacent to the first portion P1 from the outer periphery and is further outwardly disposed than the first portion P1.

[0049] 1, the coolant flow path 250 is routed not only through the first portion P1 and its interior, but also through the outer second portion P2 of the base plate 200. In other words, the coolant flow path 250 is formed so as to extend to the second portion P2, which is outer than the portion directly below the substrate W and the support portion 201 (i.e., the first portion P1, etc.). The coolant passing through the coolant flow path 250 in the second portion P2 cools a focus ring (not shown) located directly above the second portion P2, components indicated by reference numeral "400" in FIG. 2, and the like, and the outer peripheral portion of the substrate W is also cooled through these components.

[0050] In this embodiment, the diameter of the flange 202 is relatively large, and accordingly, the second portion P2 is also large. By enlarging the second portion P2 and forming the coolant flow path 250 so as to extend over substantially the entire second portion P2, it is possible to suppress a temperature rise in the outer peripheral portion of the substrate W.

[0051] 3 is a schematic top view of the configuration of coolant flow path 250 formed inside base plate 200. As described above, openings 255 and 256 are provided in surface 220 of base plate 200. Coolant flow path 250 is formed along a path connecting openings 255 and 256. For example, opening 255 is used as an inlet for the coolant, and opening 256 is used as an outlet for the coolant. The circular dotted line shown in FIG. 3 represents end E on the outer periphery of surface 110, which is the mounting surface.

[0052] In this embodiment, an opening 255 is formed in a position near the outer peripheral end of base plate 200, and an opening 256 is formed in a position at the center of base plate 200. Coolant flow path 250 connects openings 255 and 256 in a spiral shape and is routed along a path that passes through substantially the entire base plate 200.

[0053] Of the refrigerant flow path 250, the portion routed in the first portion P1 (i.e., directly below the end E) is hereinafter also referred to as "refrigerant flow path 251." As shown in Fig. 3, the refrigerant flow path 251 is routed so as to extend in an arc shape along the end E in top view.

[0054] 1, the width W1 of the refrigerant flow path 251 in the first portion P1 is narrower than the width W2 of the refrigerant flow path 250 in the second portion P2. The width of the refrigerant flow path 250 in the portion more inward than the first portion P1 is the same as the width W2 of the refrigerant flow path 250 in the second portion P2, but may be a different size. Note that the "width" of the refrigerant flow path 250 here refers to the dimension of the refrigerant flow path 250 in a direction perpendicular to the direction of the refrigerant flow when viewed from above.

[0055] In this configuration, the flow rate of the refrigerant flowing through the refrigerant flow path 251 is faster than the flow rate of the refrigerant flowing through other portions of the refrigerant flow path 250. As the flow rate increases, the heat transfer coefficient in the refrigerant flow path 251 increases, and the first portion P1 is cooled more efficiently than the second portion P2. In other words, in the refrigerant flow path 250 of this embodiment, the width of the refrigerant flow path 251 directly below the end E is narrowed, and as a result, the cooling performance for the first portion P1 is higher than the cooling performance for the second portion P2.

[0056] By providing a difference in cooling performance between the first portion P1 and the second portion P2, it is possible to sufficiently suppress a temperature rise in the outer peripheral portion of the substrate W, while preventing components such as a focus ring disposed further outward than the outer peripheral portion of the substrate W from being cooled more than necessary. This makes it possible to achieve a more uniform in-plane temperature distribution of the substrate W during processing than in the past.

[0057] The second embodiment will be described below. Differences from the first embodiment will be mainly described below, and descriptions of commonalities with the first embodiment will be omitted as appropriate.

[0058] 4 shows the configuration of the electrostatic chuck 10 according to this embodiment in a cross-sectional view similar to that of FIG. 1. In this embodiment, as in the first embodiment, a coolant flow path 250 is formed inside the base plate 200, and a part of the coolant flow path 250 (coolant flow path 251) is routed so as to pass through a first portion P1 directly below the end E. In this embodiment, the width of the coolant flow path 250, including the coolant flow path 251, is uniform throughout.

[0059] The distance between refrigerant flow path 250 and surface 110, which is a distance along a direction perpendicular to surface 110 serving as the mounting surface, is hereinafter also referred to as the "refrigerant distance." The refrigerant distance is defined for each portion of refrigerant flow path 250 and can be considered an index representing the height position of refrigerant flow path 250. As shown in FIG. 4, in this embodiment, refrigerant flow path 250 is routed so that the refrigerant distance (H1) in first portion P1 is smaller than the refrigerant distance (H2) in second portion P2. In other words, in first portion P1, refrigerant flow path 250 is located at a higher position than other portions, and is routed so as to pass through a position close to surface 110 serving as the mounting surface. The refrigerant distance of refrigerant flow path 250 in the portion inside first portion P1 is the same as the refrigerant distance (H2) in second portion P2, but may be a different distance.

[0060] In this configuration, the thermal resistance between the refrigerant flow path 251 and the surface 110 in the first portion P1 is smaller than the thermal resistance between the refrigerant flow path 250 and the surface 110 in the second portion P2. As a result, the first portion P1 is cooled more efficiently than the second portion P2. In other words, in the refrigerant flow path 250 of this embodiment, the refrigerant distance directly below the end E is reduced, and as a result, the cooling performance for the first portion P1 is higher than the cooling performance for the second portion P2. Even with this configuration, it is possible to achieve the same effects as those described in the first embodiment.

[0061] A third embodiment will be described below. The following mainly describes the differences from the first embodiment, and the description of the commonalities with the first embodiment will be omitted as appropriate.

[0062] 5 shows the configuration of the refrigerant flow path 250 formed in the base plate 200 of this embodiment in a manner similar to that of FIG. 3. In this embodiment, as in the first embodiment, the refrigerant flow path 250 is formed inside the base plate 200, and a part of it (refrigerant flow path 251) is routed so as to pass through the first portion P1 directly below the end E. The width of the refrigerant flow path 250 in this embodiment is uniform throughout, including the refrigerant flow path 251. Furthermore, the refrigerant distance in this embodiment is also uniform throughout, including the refrigerant flow path 251.

[0063] 5, in this embodiment, opening 255, which serves as an inlet for the refrigerant into refrigerant flow path 250, is formed at a position overlapping end E in top view. In other words, one end (inlet side) of refrigerant flow path 250 is disposed at a position overlapping end E in top view.

[0064] In top view, refrigerant flow path 250 extends in an arc shape from opening 255 along end E and is routed so as to pass through first portion P1. That is, the portion extending in an arc shape from opening 255 as described above constitutes refrigerant flow path 251 in this embodiment. As is clear from FIG. 5 , the refrigerant supplied to opening 255 first passes through refrigerant flow path 251 located immediately below end E and cools first portion P1. Then, the refrigerant passes through second portion P2 located outside end E and cools second portion P2. Then, the refrigerant passes through a portion inside end E and cools that portion. Finally, the refrigerant is discharged to the outside through opening 256. As the refrigerant passes through the above-described path, its temperature gradually increases.

[0065] The first portion P1 is cooled with relatively high efficiency because a low-temperature refrigerant passes through it first. On the other hand, the second portion P2 is cooled with relatively low efficiency because the refrigerant passes through it after passing through the first portion P1 and raising its temperature. That is, in the refrigerant flow path 250 of this embodiment, the inlet end portion connected to the opening 255 is located directly below the end portion E, and as a result, the cooling performance for the first portion P1 is higher than the cooling performance for the second portion P2. Even with this configuration, the same effects as those described in the first embodiment can be achieved.

[0066] Note that only one end of the refrigerant flow path 250 may be arranged at a position overlapping with the end E in a top view, or both ends may be arranged. In other words, both openings 255 and 256 may be arranged at a position directly below the end E. In such a configuration, regardless of which of the openings 255 and 256 is used as the refrigerant inlet, the first portion P1 can be cooled with high efficiency.

[0067] The configuration of the refrigerant flow paths 250 for making the cooling performance for the first portion P1 higher than the cooling performance for the second portion P2 is not limited to the example described above, and various other configurations can be adopted. For example, the distance between adjacent refrigerant flow paths 250 in a top view, i.e., the spacing between the refrigerant flow paths 250, may be varied depending on the location. Specifically, the spacing between the refrigerant flow paths 250 in the first portion P1 may be narrower than the spacing between the refrigerant flow paths 250 in the second portion P2. Even in such a configuration, the same effects as those of the above-described embodiments can be achieved.

[0068] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise. [Explanation of symbols]

[0069] 10: Electrostatic chuck 100: Dielectric substrate 101:Protrusion 110: Face 111: Seal ring 130: Adsorption electrode 140:RF electrode E: End 200: Base plate 210: Face 250, 251: refrigerant flow path P1: 1st part P2: 2nd part

Claims

1. a dielectric substrate having a mounting surface on which an object to be attracted is placed; an adsorption electrode provided inside the dielectric substrate; a base plate joined to the dielectric substrate, When viewed from a direction perpendicular to the placement surface, the dielectric substrate has a protruding portion that protrudes outward beyond the surface to be joined of the base plate, a protrusion provided on the chucking electrode;

2. Further comprising an RF electrode provided inside the dielectric substrate; When viewed from a direction perpendicular to the placement surface, 2. The electrostatic chuck according to claim 1, wherein the RF electrode is provided in a range such that an outer peripheral edge thereof does not extend beyond the outer peripheral edge of the attraction electrode.

3. a seal ring, which is an annular protrusion whose tip forms part of the mounting surface, is formed on the dielectric substrate; When viewed from a direction perpendicular to the placement surface, 2. The electrostatic chuck according to claim 1, wherein at least a portion of said seal ring overlaps with said attracting electrode.

4. The base plate is a first portion that overlaps with an outer peripheral end of the placement surface when viewed from a direction perpendicular to the placement surface; a second portion that is a portion further outwardly than the first portion, a refrigerant flow path through which a refrigerant passes is formed inside each of the first portion and the second portion, The refrigerant flow path is 2. The electrostatic chuck according to claim 1, wherein the electrostatic chuck is formed so that the cooling performance for the first portion is higher than the cooling performance for the second portion.

5. 5. The electrostatic chuck according to claim 4, wherein a width of the coolant flow passage in the first portion is narrower than a width of the coolant flow passage in the second portion.

6. When a refrigerant distance is a distance along a direction perpendicular to the mounting surface between the refrigerant flow path and the mounting surface, 5. The electrostatic chuck of claim 4, wherein the coolant distance in the first portion is smaller than the coolant distance in the second portion.

7. When viewed from a direction perpendicular to the placement surface, 5. The electrostatic chuck according to claim 4, wherein at least one end of the coolant flow path is disposed at a position overlapping an outer peripheral end of the mounting surface.

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