Electrostatic Chuck

Abstract

An electrostatic chuck capable of ensuring uniformity of plasma above a dielectric substrate even when the outer peripheral end of the dielectric substrate is protruded. [Solution] The electrostatic chuck 10 includes a dielectric substrate 100, an RF electrode 140 provided inside the dielectric substrate 100, and a base plate 200 which is a member made of metal and joined to the dielectric substrate 100. In top view, the dielectric substrate 100 has a protruding portion 101 which protrudes outward beyond a surface 210 of the base plate 200, and a part of the RF electrode 140 is provided on the protruding portion 101.

Description

[Technical field]

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

[0002] For example, in a semiconductor manufacturing device such as an etching device, an electrostatic chuck is provided 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 for supporting the dielectric substrate, which are joined together. When a voltage is applied to the attracting electrode, an electrostatic force is generated, and the substrate placed on the dielectric substrate is attracted and held.

[0003] In a semiconductor manufacturing apparatus, RF electrodes are provided as a pair of opposing electrodes for generating plasma. As described in the following Patent Document 1, a base plate of an electrostatic chuck may be used as one of the RF electrodes. Also, the RF electrode may be built into a dielectric substrate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-119654 A Summary of the Invention [Problem to be solved by the invention]

[0005] 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.

[0006] In order to prevent such a situation, the inventors have been developing an electrostatic chuck having a configuration in which the dielectric substrate is larger than the bonded surface of the base plate, i.e., the outer peripheral end of the dielectric substrate protrudes outward from the bonded surface. With this configuration, it is possible to arrange a member covering the periphery of the bonding layer below the dielectric substrate. This makes it possible to suppress the influence of the bonding layer on the substrate during processing.

[0007] If the outer edge of the dielectric substrate is protruded outward beyond the surface to be bonded, the base plate as an RF electrode will not be present directly below the protruding portion of the dielectric substrate, which may cause the plasma to become non-uniform directly above the protruding portion, resulting in uneven processing such as etching.

[0008] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide an electrostatic chuck that can ensure uniformity of plasma above a dielectric substrate, even when the outer peripheral end of the dielectric substrate is configured to protrude. [Means for solving the problem]

[0009] In order to solve the above problems, an electrostatic chuck according to the present invention includes a dielectric substrate having a mounting surface on which an object to be attracted is placed, an RF electrode provided inside the dielectric substrate, and a base plate which is a metal member and joined to the dielectric substrate. 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 RF electrode is provided on the protruding portion.

[0010] By providing a part of the RF electrode on the protruding portion, the substantially entire space directly above the dielectric substrate (including directly above the protruding portion) can be sandwiched between a pair of electrodes including the RF electrode, thereby making it possible to ensure uniformity of the plasma above the dielectric substrate. Effect of the Invention

[0011] According to the present invention, it is possible to provide an electrostatic chuck that can ensure the uniformity of plasma above a dielectric substrate even when the outer peripheral end of the dielectric substrate is configured to protrude. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view illustrating a schematic configuration of an electrostatic chuck according to a first embodiment. [Diagram 2] FIG. 2 is an enlarged view showing a part of the configuration of FIG. 1 in detail. [Diagram 3] FIG. 4 is a cross-sectional view showing a configuration of a portion of an electrostatic chuck according to a modified example of the first embodiment. [Figure 4] FIG. 11 is a cross-sectional view showing a configuration of a portion of an electrostatic chuck according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components in each drawing are denoted by the same reference numerals as much as possible, and duplicated description will be omitted.

[0014] 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 substrate W to be attracted is, for example, a silicon wafer. The electrostatic chuck 10 may be used in an apparatus other than a semiconductor manufacturing apparatus.

[0015] 1 shows, in a schematic cross-sectional view, the configuration of an electrostatic chuck 10 in a state in which the electrostatic chuck 10 attracts and holds a substrate W. The electrostatic chuck 10 includes a dielectric substrate 100 and a base plate 200.

[0016] 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 contain other materials. The purity, type, and additives of the ceramics in the dielectric substrate 100 can be appropriately set in consideration of the plasma resistance 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.

[0017] 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 "joined surface" that is joined to the base plate 200 via a joining 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 be referred to as a "top view".

[0018] An adsorption electrode 130 is embedded inside the dielectric substrate 100. The adsorption electrode 130 is a thin flat layer made of a metal material such as tungsten, and is arranged parallel to the surface 110. The material of the adsorption electrode 130 may be tungsten, molybdenum, platinum, palladium, or the like. When a voltage is applied to the adsorption electrode 130 from the outside through a power supply path (not shown), an electrostatic force is generated between the surface 110 and the substrate W, thereby adsorbing and holding the substrate W. As the configuration of the power supply path, various known configurations can be adopted. The adsorption electrode 130 may be provided as a single so-called "monopolar" electrode as in this embodiment, or may be provided as two so-called "bipolar" electrodes. The depth at which the adsorption electrode 130 is arranged, 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.

[0019] In addition to the above-mentioned attraction 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 of the opposing electrodes 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.

[0020] The RF electrode 140 is a thin flat layer made of a metal material such as tungsten, similar to the chucking electrode 130. The RF electrode 140 may be made of molybdenum, platinum, palladium, or the like, in addition to tungsten. The RF electrode 140 is embedded at a position closer to the surface 120 than the chucking electrode 130. The RF electrode 140 is disposed parallel to the surface 110, similar to the chucking electrode 130. 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.

[0021] As shown in FIG. 1, the RF electrode 140 is connected to the power feed line 14. The power feed line 14 is an electric path provided to make the potential of the RF electrode 140 equal to the potential of the base plate 200 when applying a high-frequency AC voltage between the RF electrode 140 and the other counter electrode. In FIG. 1, the power feed line 14 is illustrated in a simplified form as a whole. The power feed line 14 is configured, for example, as an electrode terminal having one end connected to the RF electrode 140 and the other end formed to protrude downward from the surface 120. The protruding portion of the power feed line 14 as described above is embedded in a recess (not shown) formed in the surface 210 of the base plate 200 and is connected to a metal portion of the base plate 200. The number of power feed lines 14 may be two or more.

[0022] 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 apparatus, helium gas for temperature adjustment is supplied from the outside to the space SP 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, and the temperature of the substrate W is thereby maintained at an appropriate temperature. The temperature adjustment gas supplied to the space SP may be a type of gas other than helium.

[0023] A seal ring 111 and dots 112 are provided on a surface 110 which is a mounting surface, and the above-mentioned space SP is formed around these.

[0024] The seal ring 111 is a wall that partitions the space SP at the outermost periphery. 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. It can be said that the tip of the seal ring 111 is the outermost part of the surface 110, which is the mounting surface.

[0025] 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 individually adjusted, and the surface temperature distribution of the substrate W during processing can be made closer to uniform.

[0026] 1, the portion marked with the reference symbol "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 part of the surface 110 to the position of the bottom surface 116.

[0027] The dots 112 are circular protrusions protruding 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.

[0028] 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. Of the base plate 200, a surface 210 on the upper side in FIG. 1 is a "bonded surface" that is bonded to the dielectric substrate 100.

[0029] The bonding layer 300 is a layer provided between the dielectric substrate 100 and the base plate 200, and bonds the two 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 any 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 that the thermal resistance between the dielectric substrate 100 and the base plate 200 is small.

[0030] The base plate 200 has a support portion 201 and a flange portion 202. The support portion 201 is an 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 like 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 of protrusion of the support portion 201 toward the upper side in FIG. 1 (the amount of protrusion from the flange portion 202) is, for example, 3 to 15 mm.

[0031] The flange portion 202 is a portion of the base plate 200 on the lower side in FIG. 1. The flange portion 202 is substantially cylindrical in shape, and its central axis coincides with the central axis of the support portion 201. The diameter of the flange portion 202 is larger than the diameter of the support portion 201. The amount of protrusion of the flange portion 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 portion 202 is, for example, 25 to 40 mm. The overall thickness of the base plate 200, including the support portion 201 and the flange portion 202, is, for example, 30 to 40 mm.

[0032] When the substrate W is processed in the semiconductor manufacturing equipment, a focus ring (not shown) is installed on the upper surface 203 of the flange portion 202. The focus ring is an annular, plate-like member made of an insulating material such as quartz, and is installed for the purpose of adjusting the distribution of plasma during processing. Substantially the entire dielectric substrate 100 and the support portion 201 are surrounded from the outer periphery by the focus ring.

[0033] 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 apparatus, 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.

[0034] 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 is also referred to as the "protruding portion 101" below. 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.

[0035] During processing such as etching, the end of the bonding layer 300 may be exposed to plasma, deteriorate, and fly apart, adversely affecting the substrate W being processed. When the protruding portion 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 the member, the effect of the bonding layer 300 on the substrate W being processed can be suppressed.

[0036] During processing such as etching, it is necessary to ensure uniformity of plasma above the dielectric substrate 100 so that processing can be performed uniformly. In the case where the dielectric substrate 100 does not have the protruding portion 101 and the entire surface 120 of the dielectric substrate 100 is supported from below by the base plate 200, for example, the base plate 200 can be made to function as an RF electrode to ensure uniformity of plasma over the entire surface directly above the surface 110. However, in the case where the dielectric substrate 100 has the protruding portion 101 as in this embodiment, the base plate 200 as an RF electrode does not exist at a position directly below the protruding portion 101. For this reason, the plasma becomes non-uniform directly above the protruding portion 101, and processing such as etching may not be performed uniformly.

[0037] Therefore, in the electrostatic chuck 10 according to this embodiment, an RF electrode 140 is provided inside the dielectric substrate 100, and the arrangement of the RF electrode 140 is devised to ensure the uniformity of the plasma during processing.

[0038] Fig. 2 shows an enlarged detailed view of the configuration of the protrusion 101 and its vicinity of the electrostatic chuck 10 in Fig. 1. The dotted line DL1 shown in Fig. 2 indicates the position of the outer circumferential end of the surface 210 to be joined. The dotted line DL2 indicates the position of the outer circumferential end of the attraction electrode 130. The dotted line DL3 indicates the position of the outer circumferential end of the RF electrode 140.

[0039] The "end portion on the outer periphery" of the RF electrode 140 refers to a portion where the smallest circle that encompasses the entire RF electrode 140 overlaps with the RF electrode 140 in a top view. The "end portion on the outer periphery" of the attraction electrode 130 is defined in a similar manner.

[0040] The diameter of the outer circumferential end of the RF electrode 140 is larger than the diameter of the surface 210 of the base plate 200. Therefore, the outer circumferential end (dotted line DL3) of the RF electrode 140 extends into the inside of the protruding portion 101 of the dielectric substrate 100.

[0041] In the configuration in which a part of the RF electrode 140 is provided on the protruding portion 101 as in this embodiment, substantially the entire space directly above the dielectric substrate 100 (including the area directly above the protruding portion 101) can be sandwiched between a pair of electrodes including the RF electrode 140. That is, even in the configuration in which the protruding portion 101 is provided on the dielectric substrate 100, the RF electrode 140 can be expanded to an area wider than the surface 210 of the base plate 200. This makes it possible to ensure uniformity of plasma above the dielectric substrate 100.

[0042] Furthermore, in this embodiment, the diameter of the outer circumferential end of the chucking electrode 130 is larger than the diameter of the surface 210 of the base plate 200. In other words, not only the RF electrode 140 but also the chucking electrode 130 are partially embedded in the protruding portion 101 in top view.

[0043] In this manner, in a configuration in which a part of the attraction electrode 130 is provided on the protrusion 101, the attraction force of the protrusion 101 to the substrate W increases, and the two are tightly attached with strong force. Although the base plate 200, which is a coolant, is not present directly below the protrusion 101, the thermal resistance between the protrusion 101 and the substrate W is reduced, so that the temperature rise of the substrate W directly above the protrusion 101 can be suppressed to some extent. As a result, the variation in the in-plane temperature distribution of the substrate W during processing can be suppressed.

[0044] 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. Moreover, 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 a top view, a part of the seal ring 111 overlaps both the protrusion 101 and the chucking electrode 130. By overlapping the seal ring 111, the protrusion 101, and the chucking electrode 130 in a top view, it is possible to further enhance cooling of the substrate W in that part. As a result, it is possible to further suppress the variation in the in-plane temperature distribution of the substrate W.

[0045] Note that 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. Also, the diameter of the outer periphery of the seal ring 111 may be made smaller than the diameter of the dielectric substrate 100 and smaller than the diameter of the outer periphery end of the chucking electrode 130.

[0046] In either case, it is preferable to secure a distance of about 0.1 mm to 3 mm from the outer peripheral end (dotted line DL2) of the chucking electrode 130 to the outer surface of the dielectric substrate 100. By securing such a distance, it is possible to prevent dielectric breakdown between the chucking electrode 130 and the outside.

[0047] The diameter of the outer circumferential end (dotted line DL3) of the RF electrode 140 is larger than the diameter of the outer circumferential end (dotted line DL1) of the adsorption electrode 130. That is, the RF electrode 140 is provided in a range where its outer circumferential end is more outer than the outer circumferential end of the adsorption electrode 130 in a top view. It is preferable to secure a distance of about 0.1 mm to 2 mm from the outer circumferential end (dotted line DL3) of the RF electrode 140 to the outer surface of the dielectric substrate 100.

[0048] The potential of the RF electrode 140 during processing is generally set to be smaller than the potential of the chucking electrode 130. As in this embodiment, by extending the outer peripheral end of the RF electrode 140 outward beyond the outer peripheral end of the chucking electrode 130, the RF electrode 140 can be provided over as wide an area as possible within a range in which the dielectric strength voltage can be ensured. As a result, the uniformity of the plasma can be ensured.

[0049] As described above, it is preferable that the diameter of the outer peripheral end of the RF electrode 140 is larger than the diameter of the joined surface (surface 210) of the base plate 200. The "joined surface" here refers to the surface of the metal part of the base plate 200 that faces the dielectric substrate via the bonding layer 300. The "joined surface" can be defined in the same manner as above even when the surface 210 is covered with an insulating film.

[0050] 3, an insulating film 230 is formed so as to cover the surface of the base plate 200 including the surface 210. The insulating film 230 is, for example, an alumina film formed by thermal spraying. The thickness of the insulating film is, for example, 1 mm or less.

[0051] 3, the portion of surface 210 near the outer circumferential end is not flat but curved in an arc. Such a curved portion of surface 210 is hereinafter also referred to as "surface 210A." In this modification, the entire surface 210 including surface 210A is defined as a "bonded surface" that is bonded to dielectric substrate 100 via insulating film 230 and bonding layer 300.

[0052] 3, the reference symbol "211" is given to the outer surface of the support part 201. Hereinafter, this outer surface will also be referred to as the "outer surface 211." When viewed from above, the position of the outer peripheral end of the joined surface (dotted line DL1) and the position of the outer surface 211 are equal to each other.

[0053] When the surface of the base plate 200 is covered with the insulating film 230 as in this modified example, the portion of the dielectric substrate 100 that is outside the dotted line DL1 in top view corresponds to the protruding portion 101. Moreover, the chucking electrode 130 and the RF electrode 140 are formed so as to extend to a position that is outside the dotted line DL1.

[0054] A second embodiment will be described below. In the following, differences from the first embodiment will be mainly described, and descriptions of commonalities with the first embodiment will be omitted as appropriate.

[0055] Fig. 4 illustrates the configuration of the electrostatic chuck 10 according to this embodiment from the same perspective as Fig. 2. As shown in Fig. 4, in this embodiment, the diameter of the outer circumferential end (dotted line DL3) of the RF electrode 140 is smaller than the diameter of the outer circumferential end (dotted line DL2) of the attraction electrode 130. In other words, the RF electrode 140 is provided in a range in which its outer circumferential end is on the inner circumferential side of the outer circumferential end of the attraction electrode 130 in a top view.

[0056] When the substrate W is being processed, Joule heat is generated in the RF electrode 140, which may increase the temperature of the surrounding members. In other words, the RF electrode 140 may become a heat source during processing. Therefore, in this embodiment, as described above, the RF electrode 140 is provided in a range in which its outer circumferential end is more inward than the outer circumferential end of the attraction electrode 130. By keeping the RF electrode 140, which is a heat source, within the above range, it is possible to suppress a temperature rise in the outer circumferential portion of the substrate W.

[0057] Incidentally, the outer peripheral end of the RF electrode 140 may overlap with the outer peripheral end of the adsorption electrode 130 in top view. In other words, it is sufficient that the outer peripheral end of the RF electrode 140 is provided in a range that does not protrude beyond the outer peripheral end of the adsorption electrode 130.

[0058] In a configuration in which the outer peripheral end of the RF electrode 140 is recessed into the protruding portion 101, if heat generation from the RF electrode 140 becomes a problem, the configuration of this embodiment may be adopted instead of the first embodiment.

[0059] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Any design modifications made by a person skilled in the art to these specific examples are also included within the scope of the present disclosure as long as they have the features of the present disclosure. The elements of each of the above-mentioned specific examples and their arrangements, conditions, shapes, etc. are not limited to those exemplified and can be changed as appropriate. The combination of each of the elements of each of the above-mentioned specific examples can be changed as appropriate as long as no technical contradiction occurs. [Explanation of symbols]

[0060] 10: Electrostatic chuck 100: Dielectric substrate 101:Protrusion 110: Face 130: Adsorption electrode 140:RF electrode 200: Base plate 210: Face

Claims

1. a dielectric substrate having a mounting surface on which an object to be attached is placed; An RF electrode provided inside the dielectric substrate; a base plate made of metal and joined to the dielectric substrate; When viewed from a direction perpendicular to the placement surface, the dielectric substrate has a protruding portion protruding outward from a surface to be joined of the base plate, A portion of the RF electrode is provided on the protruding portion, The dielectric substrate further includes an adsorption electrode provided inside the dielectric substrate, When viewed from a direction perpendicular to the placement surface, a part of the chucking electrode is provided on the protruding portion, The electrostatic chuck is characterized in that an outer peripheral end of the RF electrode is provided in a range that is more outer than an outer peripheral end of the attraction electrode.

2. A dielectric substrate having a mounting surface on which an object to be attracted is placed; An RF electrode provided inside the dielectric substrate; a base plate made of metal and joined to the dielectric substrate; When viewed from a direction perpendicular to the placement surface, the dielectric substrate has a protruding portion protruding outward from a surface to be joined of the base plate, A portion of the RF electrode is provided on the protruding portion, The dielectric substrate further includes an adsorption electrode provided inside the dielectric substrate, When viewed from a direction perpendicular to the placement surface, a part of the chucking electrode is provided on the protruding portion, The electrostatic chuck is characterized in that the RF electrode is provided in a range such that an outer peripheral end portion thereof does not extend beyond an outer peripheral end portion of the attraction electrode.

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