Electrostatic chuck

Abstract

To provide an electrostatic chuck capable of suppressing variation in in-plane temperature distribution of a substrate during a process.SOLUTION: An electrostatic chuck 10 includes a dielectric substrate 100, an RF electrode 140 provided inside the dielectric substrate 100, a base plate 200 formed of metal and bonded to the dielectric substrate 100, and a plurality of connection members 400 electrically connecting the RF electrode 140 and the base plate 200. The dielectric substrate 100 includes a plurality of gas holes 114 in a top view. The connection members 400 and the gas holes 114 are arranged in a line and in an annular shape.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] For example, semiconductor manufacturing equipment such as etching equipment is provided 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 that supports 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] As described in Patent Document 1 below, a dielectric substrate may have an RF electrode built in, which is one of a pair of opposing electrodes for generating plasma in a semiconductor manufacturing apparatus. In this case, the RF electrode and the base plate are electrically connected via a conductive connecting member. This allows the potential of the RF electrode to be maintained at the potential of the base plate (e.g., ground potential) during substrate processing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 255118 Summary of the Invention [Problem to be solved by the invention]

[0005] To electrically connect the connecting member and the RF electrode, for example, a recess may be formed on the surface of the dielectric substrate facing the base plate, the RF electrode may be exposed at the bottom, and the connecting member may be accommodated inside the recess. To electrically connect the RF electrode and the base plate via the connecting member, for example, a recess may also be formed on the surface of the base plate facing the dielectric substrate, and the connecting member may be accommodated inside the recess. The connecting member is sandwiched between the dielectric substrate and the base plate.

[0006] When a substrate is processed in a semiconductor manufacturing device, Joule heat is generated in the connecting member due to the application of an AC voltage to the RF electrode. Depending on the amount of heat generated by the connecting member, the portion of the dielectric substrate directly above the connecting member may be locally overheated by the heat from the connecting member.

[0007] In this way, the connecting member can become a heat source for the dielectric substrate and the object to be attracted, and therefore, depending on the position of the connecting member, there is a possibility that the temperature distribution within the surface of the substrate during processing may vary too much.

[0008] 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. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides an electrostatic chuck comprising: 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, and a plurality of connecting members that electrically connect the RF electrode and the base plate. When viewed from a direction perpendicular to the mounting surface, a plurality of gas holes are formed in the dielectric substrate, and the connecting members and the gas holes are arranged in a line in an annular shape.

[0010] The gas holes are for supplying an inert gas (e.g., helium gas) for temperature adjustment between the object to be attracted and the dielectric substrate. Therefore, the gas holes can serve as a cooling source for the object to be attracted during processing. In the electrostatic chuck having the above configuration, the connecting member, which can serve as a heating source, and the gas holes, which can serve as a cooling source, are arranged in a line in an annular shape. As a result, the distance between the connecting member and the gas holes is reduced, making it difficult for localized temperature increases to occur, thereby suppressing variations in the in-plane temperature distribution of the object to be attracted during processing. [Effects of the Invention]

[0011] 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. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view schematically showing the configuration of an electrostatic chuck according to a first embodiment. [Figure 2] 2 is a diagram showing the configuration of the mounting surface side of a dielectric substrate provided in the electrostatic chuck of FIG. 1. FIG. [Figure 3] 2 is a cross-sectional view showing in detail the configuration of a connecting member and its surrounding area of ​​the electrostatic chuck according to the first embodiment. FIG. [Figure 4] FIG. 2 is a perspective view showing a configuration of a connecting member. [Figure 5] 10 is a diagram showing the configuration of the mounting surface side of a dielectric substrate according to a second embodiment. FIG. [Figure 6] FIG. 10 is a cross-sectional view showing in detail the configuration of a connecting member and its surrounding area in an electrostatic chuck according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] 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.

[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 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.

[0015] 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.

[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 also 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 and other properties required of the dielectric substrate 100 in semiconductor manufacturing equipment.

[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 "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."

[0018] An attraction electrode 130 is embedded inside the dielectric substrate 100. The attraction electrode 130 is a thin, flat layer made of a metal material such as tungsten, and is disposed parallel to the surface 110. The attraction electrode 130 may be made of a material other than tungsten, such as molybdenum, platinum, or palladium. When a voltage is applied to the attraction electrode 130 from the outside via a power supply path (not shown), an electrostatic force is generated between the surface 110 and the substrate W, thereby attracting and holding the substrate W. The power supply path may be configured in any of various well-known ways. The attraction electrode 130 may be provided as a single so-called "monopolar" electrode as in this embodiment, or as two so-called "bipolar" electrodes.

[0019] 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.

[0020] Like the chucking electrode 130, the RF electrode 140 is a thin, flat layer made of a metal material such as tungsten. In addition to tungsten, molybdenum, platinum, palladium, etc. may also be used as the material of the RF electrode 140. The RF electrode 140 is embedded at a position closer to the surface 120 than the chucking electrode 130. Like the chucking electrode 130, the RF electrode 140 is disposed so as to be 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 in top view coincides with the center of the dielectric substrate 100.

[0021] The electrostatic chuck 10 is provided with a connecting member 400. The connecting member 400 is a member for electrically connecting the RF electrode 140 and a base plate 200, which will be described later. The connecting member 400 makes the potential of the RF electrode 140 the same as the potential of the base plate 200 during processing of the substrate W. In FIG. 1, the connecting member 400 is schematically depicted as a simple straight line. The specific shape of the connecting member 400 will be described later.

[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 equipment, helium gas for temperature adjustment is supplied to the space SP from the outside through a gas hole 114 (see Fig. 2), not shown in Fig. 1. 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 type of gas other than helium.

[0023] 2 is a top view of the dielectric substrate 100. As shown in the figure, a seal ring 150 and dots 113 are provided on the surface 110, which is the mounting surface, and the space SP is formed around these. Note that the dots 113 are not shown in FIG.

[0024] The seal ring 150 is an annular protrusion provided as a wall that divides the space SP. A plurality of seal rings 150 are provided, and are arranged in a substantially concentric pattern when viewed from above. The tip surface (the upper end surface in FIG. 1) of each seal ring 150 forms part of the surface 110 and abuts against the substrate W. In this embodiment, a total of two seal rings 150 are provided, thereby dividing the space SP into two. With this configuration, it is possible to individually adjust the pressure of the helium gas in each space SP and make the surface temperature distribution of the substrate W during processing more uniform.

[0025] The seal ring 150 disposed on the outside will also be referred to as the "first seal ring 151" below. The seal ring 150 disposed on the inside will also be referred to as the "second seal ring 152" below.

[0026] The first seal ring 151 is a seal ring 150 that is arranged at a position that is the outermost edge of the surface 110 that is the mounting surface. The second seal ring 152 is a seal ring 150 that is arranged at a position that is inside the first seal ring 151, without any other seal rings 150 being sandwiched between them. An embodiment in which another seal ring 150 is provided inside the second seal ring 152 may also be adopted. Alternatively, an embodiment in which only one first seal ring 151 is provided, and no other seal rings 150 are present may also be adopted.

[0027] 1 and 2, the portion designated by 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 150, together with the dots 113 described below, is formed by digging down a portion of the surface 110 to the position of the bottom surface 116.

[0028] The dots 113 are circular protrusions that protrude from the bottom surface 116. As shown in FIG. 2, a plurality of dots 113 are provided and are dispersedly arranged on the mounting surface of the dielectric substrate 100. The upper end surface of each dot 113 forms part of the surface 110 and abuts against the substrate W. By providing a plurality of such dots 113, bending of the substrate W is suppressed.

[0029] Of the multiple dots 113, a group of dots 113 that are arranged at a position closest to the first seal ring 151 from the inside and that are arranged in a ring shape along the first seal ring 151 will also be referred to as "dots 113A" below. Also, of the multiple dots 113, a group of dots 113 that are arranged at a position closest to the second seal ring 152 from the inside and that are arranged in a ring shape along the second seal ring 152 will also be referred to as "dots 113B" below.

[0030] The dots 113 may be evenly dispersed over the entire mounting surface of the dielectric substrate 100, or may be densely arranged in some areas. In this embodiment, the arrangement density of the dots 113 in the outer periphery when viewed from above is higher than the arrangement density of the dots 113 in the central area. Specifically, the arrangement density of the dots 113A and dots 113B is higher than the arrangement density of the other dots 113. By arranging the multiple dots 113 in this manner, it is possible to efficiently cool the outer periphery, which is a part of the substrate W that is likely to become relatively hot, and to suppress variations in the in-plane temperature distribution of the substrate W.

[0031] As shown in Fig. 2, a plurality of gas holes 114 are formed in the dielectric substrate 100. The gas holes 114 are not shown in Fig. 1. The gas holes 114 are holes for supplying helium gas to the space SP, and are circular through-holes formed to extend perpendicularly from the surface 120 toward the surface 110. Helium gas supplied from the outside passes through gas flow paths (not shown) formed inside the base plate 200, and is then supplied to the space SP through each gas hole 114.

[0032] In this embodiment, a plurality of gas holes 114 are connected to each of the two divided spaces SP. A porous body made of, for example, alumina may be disposed inside the gas holes 114. With this configuration, it is possible to prevent dielectric breakdown in the path through the gas holes 114 while ensuring the flow of gas through the gas holes 114.

[0033] Grooves may be formed on the bottom surface 116 of the space SP in order to increase the in-plane diffusion rate of the helium gas.

[0034] Returning to FIG. 1 , the explanation will continue. The base plate 200 is a substantially disk-shaped member that supports the dielectric substrate 100. The base plate 200 is formed from 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, the upper surface 210 in FIG. 1 is the "bonded surface" that is bonded to the dielectric substrate 100.

[0035] 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.

[0036] 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.

[0037] 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 an opening (not shown) formed in a surface 220 of the base plate 200 opposite to the surface 210.

[0038] The specific configuration of the connection member 400 and its vicinity will be described with reference to FIG. 3 and the like. As shown in FIG. 3, a first recess 160 is formed in the surface 120 of the dielectric substrate 100 facing the base plate 200. The first recess 160 is a portion of the surface 120 recessed toward the surface 110 to allow the connection member 400 to be disposed therein. The first recess 160 of this embodiment is formed to a depth position that exposes the RF electrode 140. Therefore, the RF electrode 140, which is an internal electrode, is exposed at a bottom surface 162 of the first recess 160. The first recess 160 has a circular shape when viewed from above, and a substantially cylindrical space is formed inside the circular shape.

[0039] A second recess 260 is formed in the surface 210 of the base plate 200 facing the dielectric substrate 100. The second recess 260 is formed in a portion of the surface 210 that overlaps with the first recess 160 in a top view. The second recess 260 is a portion of the surface 210 that is recessed toward the surface 220 to allow for the placement of the connecting member 400. Inside the second recess 260, the entire metal portion of the base plate 200 is exposed. The second recess 260 has a circular shape in a top view, and a substantially cylindrical space is formed inside it. The central axis of the second recess 260 coincides with the central axis of the first recess 160. However, the diameter of the inner circumferential surface 261 of the second recess 260 is smaller than the diameter of the inner circumferential surface 161 of the first recess 160.

[0040] A circular opening is formed in the bonding layer 300 in a portion between the first recess 160 and the second recess 260. The first recess 160 and the second recess 260 are connected via this opening, and the entirety of these recesses forms a single space.

[0041] The member marked with the reference symbol "310" in FIG. 3 is a member arranged to prevent uncured adhesive from entering the inside of the first recess 160 or the second recess 260. This member is also referred to as "blocking portion 310" below. The blocking portion 310 is an annular member arranged to surround the entire circumference of the first recess 160 from the outside when viewed from above. The inner diameter of the blocking portion 310 is the same as the inner diameter of the first recess 160, but may be different from the inner diameter of the first recess 160. For example, a cured silicone adhesive is used as the blocking portion 310.

[0042] The connecting member 400 is a substantially cylindrical member formed from a fibrous metal member, and is housed inside the first recess 160 and the second recess 260. In other words, a portion of the connecting member 400 is housed in the first recess 160, and another portion of the connecting member 400 is housed in the second recess 260.

[0043] The connecting member 400 abuts against the RF electrode 140 exposed at the bottom surface 162 of the first recess 160. The connecting member 400 also abuts against the metal portion of the base plate 200 exposed at the bottom surface 262 of the second recess 260. The connecting member 400 arranged in this manner electrically connects the RF electrode 140 and the metal portion of the base plate 200.

[0044] 4, connecting member 400 has a cylindrical main body 410 and multiple protrusions 420, and the entire connecting member 400 is integrally formed from a fibrous metal material. Connecting member 400 has a circular shape when viewed from above. The diameter of this circle, i.e., the diameter of main body 410, is hereinafter also referred to as "diameter D1."

[0045] The protrusions 420 are generally cylindrical projections formed so as to extend from the surface of the main body 410 facing the dielectric substrate 100 toward the dielectric substrate 100. In this embodiment, a total of four protrusions 420 are formed, but the number of protrusions 420 may be different.

[0046] The connecting member 400, which is made of a fibrous metal member, has sufficient breathability to allow fluids such as air and adhesive to penetrate inside. In other words, the fibrous metal member is not dense enough, and there are gaps between the fibers. With this configuration, each part of the connecting member 400, including the protruding portion 420, is an elastic body that can easily deform when subjected to an external force.

[0047] When no external force is applied, the dimension of the connecting member 400 in the up-down direction (the direction in which the protrusions 420 extend) is larger than the dimension in the same direction in the state shown in Fig. 4. In other words, the connecting member 400 is housed inside the first recess 160 and the second recess 260 in a state in which it is compressed in the direction from the dielectric substrate 100 toward the base plate 200, and is sandwiched between the RF electrode 140 and the base plate 200. The tip of each protrusion 420 is elastically deformed so as to be crushed when pressed against the bottom surface 162 of the first recess 160 (i.e., the RF electrode 140).

[0048] The connecting member 400 is pressed against the RF electrode 140 and the base plate 200 by its own restoring force. Therefore, even if thermal expansion or contraction occurs in each part of the electrostatic chuck 10 during processing of the substrate W, etc., the electrical connection between the RF electrode 140 and the base plate 200 is always maintained.

[0049] The shape of the connection member 400 may be different from that shown in Fig. 4. For example, the entire connection member 400 may be substantially cylindrical, and may not have the protrusion 420.

[0050] The electrostatic chuck 10 is provided with a plurality of the above-described connecting members 400. Fig. 2 shows the positions of the plurality of connecting members 400 provided in the electrostatic chuck 10. In an actual configuration, the connecting members 400 cannot be seen from the surface 110 side, but for convenience of explanation, Fig. 2 depicts each connecting member 400 so that it can be seen from the surface 110 side through the dielectric substrate 100.

[0051] 2, each of the multiple connecting members 400 is disposed in the region between the first seal ring 151 and the second seal ring 152 when viewed from above. The diameter D1 of the connecting member 400 when viewed from above is smaller than the distance D2 between the first seal ring 151 and the second seal ring 152.

[0052] The multiple connecting members 400 are arranged in a ring shape along the second seal ring 152. The dashed-dotted line DL shown in Fig. 2 is an imaginary line extending parallel to the second seal ring 152. In top view, the dashed-dotted line DL is circular, and its center coincides with the center of the dielectric substrate 100 or the base plate 200. In top view, all connecting members 400 are arranged so that the center position of each connecting member 400 is located on the dashed-dotted line DL.

[0053] In the present embodiment, each connecting member 400 is disposed at a position where the entire connecting member 400 does not overlap with either the first seal ring 151 or the second seal ring 152 in top view. In other words, when focusing on any one connecting member 400, the connecting member 400 does not overlap with any of the seal rings 150 in top view. The same applies to all connecting members 400 provided in the electrostatic chuck 10.

[0054] 2, in addition to the connecting member 400, a plurality of gas holes 114 are also arranged in the portion between the first seal ring 151 and the second seal ring 152. All of the gas holes 114 arranged in this portion are arranged so that their centers are positioned on the dashed line DL in top view. That is, in this embodiment, the connecting member 400 and the gas holes 114 are arranged in a line and in a ring shape in top view.

[0055] Incidentally, when the substrate W is being processed in the semiconductor manufacturing equipment, Joule heat is generated in the connection member 400 as an AC voltage is applied to the RF electrode 140. Depending on the amount of heat generated by the connection member 400, the portion of the dielectric substrate 100 directly above the connection member 400 may be locally overheated by the heat from the connection member 400.

[0056] In this way, the connection member 400 can serve as a heat source for the dielectric substrate 100 and the substrate W. Therefore, depending on the position of the connection member 400, there is a possibility that the in-plane temperature distribution of the substrate W during processing may vary too much.

[0057] On the other hand, the gas holes 114 are for supplying a gas for adjusting the temperature to the space SP between the substrate W and the dielectric substrate 100. Therefore, the gas holes 114 can serve as a cooling source for the substrate W during processing.

[0058] Therefore, in the electrostatic chuck 10 according to this embodiment, the connecting member 400, which can serve as a heating source, and the gas holes 114, which can serve as a cooling source, are arranged in a line and in an annular shape when viewed from above, as described above. As a result, the distance between the connecting member 400 and the gas holes 114 is reduced, making it difficult for a local temperature rise to occur, thereby suppressing variations in the in-plane temperature distribution of the substrate W during processing.

[0059] Furthermore, in this embodiment, the connecting members 400 and the gas holes 114 are arranged alternately in the circumferential direction when viewed from above. With this configuration, the distance between the connecting members 400 and the gas holes 114 is further reduced, thereby making it possible to further uniform the in-plane temperature distribution of the substrate W during processing.

[0060] In the present embodiment, all of the connecting members 400 and the gas holes 114 provided in the electrostatic chuck 10 are arranged in a line in a circular shape in a top view, and are alternately arranged along the dashed-dotted line DL in FIG. 2 . Instead of this configuration, some of the connecting members 400 and the gas holes 114 may be arranged in positions different from those described above. That is, only some of the connecting members 400 and the gas holes 114 may be arranged in a line in a circular shape. Similarly, only some of the connecting members 400 and the gas holes 114 may be arranged alternately along the dashed-dotted line DL in FIG. 2 .

[0061] In this embodiment, the plurality of connecting members 400 provided on the electrostatic chuck 10 are all disposed at positions where their centers are located between the first seal ring 151 and the second seal ring 152 in a top view. As a result, the plurality of connecting members 400 are disposed side by side on the outer circumferential side of the dielectric substrate 100.

[0062] It is known that during processing of a substrate W in a semiconductor manufacturing apparatus, the AC current flowing between a pair of opposing electrodes including the RF electrode 140 tends to flow unevenly toward the outer periphery of the dielectric substrate 100. Therefore, in this embodiment, the connection member 400, which is part of the electrical path, is disposed in the outer periphery where the AC current flows relatively easily. This allows the path along which the AC current flows to be roughly the shortest, thereby enabling plasma to be drawn into the substrate W efficiently.

[0063] The above-described arrangement of the connecting member 400 and the gas holes 114 can also be adopted in a configuration in which only one first seal ring 151 is provided as the seal ring 150.

[0064] 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.

[0065] 5 is a top view of the dielectric substrate 100 according to this embodiment. Note that the dots 113 and gas holes 114 arranged inside the second seal ring 152 are omitted from the drawing. The dots 113 arranged between the first seal ring 151 and the second seal ring 152 are also omitted from the drawing.

[0066] In this embodiment, the portion of the first seal ring 151 designated by the reference numeral "151A" is not arc-shaped but extends linearly. This portion will also be referred to as the "non-circular portion 151A" below. Similarly, in this embodiment, the portion of the second seal ring 152 designated by the reference numeral "152A" is not arc-shaped but extends linearly. This portion will also be referred to as the "non-circular portion 152A" below. The non-circular portions 151A and 152A correspond to alignment orientation flats or notches provided on the substrate W (silicon wafer).

[0067] The dashed-dotted line DL shown in Fig. 5 is an imaginary line extending parallel to the second seal ring 152. The portion of the dashed-dotted line DL adjacent to the non-circular portion 152A extends linearly parallel to the non-circular portion 152A. The remaining portion of the dashed-dotted line DL extends in an arc shape similar to the dashed-dotted line DL in Fig. 2, and the center of the arc coincides with the center of the dielectric substrate 100 or the base plate 200. In a top view, all of the connecting members 400 are arranged so that the center of each connecting member 400 is located on the dashed-dotted line DL.

[0068] The gas holes 114 arranged in the portion between the first seal ring 151 and the second seal ring 152 are all arranged so that the center position in top view is on the dashed dotted line DL.

[0069] That is, in this embodiment, as in the first embodiment, the connection members 400 and the gas holes 114 are arranged in a line in an annular shape when viewed from above, and are also arranged alternately along the dashed dotted line DL.

[0070] As described above, the arrangement of the connection members 400, etc., arranged "in a line and in a circular shape" includes not only the arrangement in which the entire connection members 400, etc., are arranged in a circular shape as in the first embodiment, but also the arrangement in which some of the connection members 400, etc., are arranged in a straight line as in this embodiment. The above-mentioned configuration also achieves the same effects as those described in the first embodiment.

[0071] 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.

[0072] Fig. 6 illustrates the configuration of the electrostatic chuck 10 according to this embodiment from the same perspective as Fig. 3. As shown in Fig. 6, the first recess 160 according to this embodiment is not formed to a depth position that exposes the RF electrode 140. A bottom surface 162 of the first recess 160 is located closer to the surface 120 than the RF electrode 140.

[0073] The bottom surface 162 of the first recess 160 is covered with a metal plate 141. The metal plate 141 is a plate-shaped member made of, for example, molybdenum, and is in close contact with almost the entire bottom surface 162. In this embodiment, the tip of the protrusion 420 is pressed against the metal plate 141.

[0074] The metal plate 141 and the RF electrode 140 are electrically connected by a plurality of via portions 142 provided in the dielectric substrate 100. The via portions 142 are holes formed to extend in a direction perpendicular to the surface 120 and filled with a conductive material such as tungsten. One end of each of the via portions 142 is connected to the metal plate 141, and the other end is connected to the RF electrode 140.

[0075] As described above, in this embodiment, the connection member 400 and the RF electrode 140 are not directly connected to each other, but are indirectly connected to each other through the metal plate 141 and the via portion 142. Even in this embodiment, the same effects as those described in the first embodiment can be achieved.

[0076] 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]

[0077] 10: Electrostatic chuck 100: Dielectric substrate 110: Face 114: Gas hole 140:RF electrode 200: Base plate 400: Connection parts W: Substrate

Claims

1. 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 bonded to the dielectric substrate; a plurality of connection members electrically connecting the RF electrode and the base plate; When viewed from a direction perpendicular to the placement surface, a plurality of gas holes are formed in the dielectric substrate; The electrostatic chuck is characterized in that the connecting member and the gas holes are arranged in a line and in an annular shape.

2. When viewed from a direction perpendicular to the placement surface, 2. The electrostatic chuck according to claim 1, wherein the connecting members and the gas holes are arranged alternately in the circumferential direction.

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