Electrostatic chuck

Abstract

Provided is an electrostatic chuck capable of suppressing variation in the in-plane temperature distribution of a substrate during processing. This electrostatic chuck 10 comprises: a dielectric substrate 100; a seal ring 150 which is an annular protrusion formed on the dielectric substrate 100; an RF electrode 140 provided inside the dielectric substrate 100; a base plate 200 formed of metal and joined to the dielectric substrate 100; and a connection member 400 electrically connecting the RF electrode 140 and the base plate 200. In a top view, the connection member 400 is positioned so that at least a portion of the connection member does not overlap the seal ring 150.

Description

Electrostatic chuck

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

[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] The mounting surface of a dielectric substrate often has annular protrusions called "seal rings" or tiny circular protrusions called "dots." The substrate is held by suction while abutting against the tips of the seal rings or dots.

[0004] As described in Patent Document 1 below, a dielectric substrate may incorporate an RF electrode, which is one of a pair of opposing electrodes for generating plasma in a semiconductor manufacturing apparatus. In this case, the RF electrode and a 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.

[0005] International Publication No. 2022 / 255118

[0006] To electrically connect the above-mentioned 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 housed 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 housed inside the recess. The connecting member is sandwiched between the dielectric substrate and the base plate.

[0007] However, the thermal conductivity of the connection member is relatively high, so there is a possibility that the portion of the dielectric substrate directly above the connection member may be locally overcooled due to heat transfer to the base plate via the connection member.

[0008] Furthermore, 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.

[0009] In this way, the connecting member can serve as both a heating source and a cooling source for the dielectric substrate, and therefore, depending on the position of the connecting member, there is a possibility that the in-plane temperature distribution of the substrate during processing may vary too much.

[0010] 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.

[0011] In order to achieve the above object, 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, a seal ring which is an annular protrusion formed on the dielectric substrate and whose tip surface forms part of the mounting surface, an RF electrode provided inside the dielectric substrate, a base plate made of metal and joined to the dielectric substrate, and a connecting member which electrically connects the RF electrode and the base plate. When viewed from a direction perpendicular to the mounting surface, the connecting member is positioned so that at least a portion of the connecting member does not overlap with the seal ring.

[0012] In the electrostatic chuck having the above configuration, local temperature increases or decreases occurring in the seal ring can be suppressed compared to a configuration in which the entire connecting member overlaps the seal ring in a top view, and as a result, variations in the in-plane temperature distribution of the substrate supported by the seal ring can also be suppressed.

[0013] 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.

[0014] FIG. 1 is a cross-sectional view schematically showing the configuration of an electrostatic chuck according to a first embodiment; FIG. 2 is a view showing the configuration of a mounting surface side of a dielectric substrate included in the electrostatic chuck of FIG. 1; FIG. 3 is a cross-sectional view showing in detail the configuration of a connecting member and its vicinity in the electrostatic chuck according to the first embodiment; FIG. 4 is a perspective view showing the configuration of a connecting member; FIG. 5 is a view showing the configuration of a mounting surface side of a dielectric substrate according to a second embodiment; FIG. 6 is a view showing the configuration of a mounting surface side of a dielectric substrate according to a third embodiment; and FIG. 7 is a cross-sectional view showing in detail the configuration of a connecting member and its vicinity in the electrostatic chuck according to a fourth embodiment.

[0015] 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.

[0016] 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 also be used in apparatuses other than semiconductor manufacturing apparatuses.

[0017] 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.

[0018] The dielectric substrate 100 is a substantially disk-shaped member made of a sintered ceramic body. The dielectric substrate 100 is made of, for example, high-purity aluminum oxide (Al ２ O ３ 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.

[0019] 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."

[0020] 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 disposed parallel to the surface 110. The adsorption electrode 130 may be made of molybdenum, platinum, palladium, or the like, in addition to tungsten. When a voltage is applied to the adsorption 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 adsorbing and holding the substrate W. Various known configurations can be employed as the configuration of the power supply path. Only one adsorption electrode 130 may be provided as a so-called "monopolar" electrode, as in this embodiment, or two may be provided as so-called "bipolar" electrodes.

[0021] 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 apparatus. The other opposing electrode is provided at a position above the electrostatic chuck 10 in the semiconductor manufacturing apparatus. 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.

[0022] 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 in top view coincides with the center of the dielectric substrate 100.

[0023] 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.

[0024] 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 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.

[0025] 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 mounting surface 110, and the space SP is formed around these. Note that the dots 113 are not shown in FIG.

[0026] 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.

[0027] The seal ring 150 disposed on the outside will also be referred to as the "first seal ring 151" hereinafter. The seal ring 150 disposed on the inside will also be referred to as the "second seal ring 152" hereinafter.

[0028] The first seal ring 151 is a seal ring 150 that is arranged at the outermost position of the surface 110, which is the mounting surface. The second seal ring 152 is a seal ring 150 that is arranged at a position inside the first seal ring 151, without another seal ring 150 being sandwiched between the first seal ring 151 and the second seal ring 152. An embodiment in which another seal ring 150 is further provided inside the second seal ring 152 may also be adopted.

[0029] 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.

[0030] The dots 113 are circular protrusions protruding 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 comes into contact with the substrate W. By providing a plurality of such dots 113, bending of the substrate W is suppressed.

[0031] 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" hereinafter. 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" hereinafter.

[0032] 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 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.

[0033] 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.

[0034] 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.

[0035] A groove 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.

[0036] Returning to Figure 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 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, the upper surface 210 in Figure 1 is the "bonded surface" that is bonded to the dielectric substrate 100.

[0037] 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 hardening 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 hardening 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.

[0038] 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 the insulating film, the dielectric strength of the base plate 200 can be increased.

[0039] 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.

[0040] The specific configuration of the connecting member 400 and its surrounding area will be described with reference to FIG. 3 and other figures. 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 connecting member 400 to be disposed therein. The first recess 160 in 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.

[0041] 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 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.

[0042] 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.

[0043] The member marked with the reference numeral "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 will also be 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 a different size from the inner diameter of the first recess 160. For example, a cured silicone adhesive is used as the blocking portion 310.

[0044] 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.

[0045] 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.

[0046] 4, the connecting member 400 has a cylindrical main body 410 and a plurality of protrusions 420, and the entire connecting member 400 is integrally formed from a fibrous metal material. The shape of the connecting member 400 when viewed from above is circular. The diameter of the circle, i.e., the diameter of the main body 410, is hereinafter also referred to as "diameter D1."

[0047] 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.

[0048] 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.

[0049] When not subjected to an external force, 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 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).

[0050] 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, the electrical connection between the RF electrode 140 and the base plate 200 is always maintained.

[0051] 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.

[0052] Although the number of connecting members 400 may be one, in this embodiment, a plurality of connecting members 400 are provided. Fig. 2 shows the positions of the plurality of connecting members 400 provided in the electrostatic chuck 10. Note that 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.

[0053] 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 in a top view. The diameter D1 of the connecting member 400 in a top view is smaller than the distance D2 between the first seal ring 151 and the second seal ring 152.

[0054] 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 of each connecting member 400 is located on the dashed-dotted line DL.

[0055] In this 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.

[0056] However, since the connecting member 400 is made of metal, its thermal conductivity is relatively high. Therefore, there is a possibility that the portion of the dielectric substrate 100 directly above the connecting member 400 may be locally overcooled due to heat transfer to the base plate 200 via the connecting member 400.

[0057] Furthermore, when the substrate W is being processed in the semiconductor manufacturing equipment, Joule heat is generated in the connection member 400 in association with the application of an AC voltage 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.

[0058] In this way, the connecting member 400 can serve as both a heating source and a cooling source for the dielectric substrate 100. For this reason, if the connecting member 400 is arranged at a position overlapping the seal ring 150 in a top view, the portion of the seal ring 150 directly above the connecting member 400 may be locally overheated or overcooled as described above. Because the seal ring 150 abuts against the substrate W, if a local temperature rise or fall occurs in the seal ring 150, the in-plane temperature distribution of the substrate W during processing may vary excessively.

[0059] Therefore, in the electrostatic chuck 10 according to this embodiment, as described above, the connecting member 400 is disposed at a position where it does not entirely overlap the seal ring 150. In this configuration, local temperature increases or decreases occurring in the seal ring 150 can be suppressed compared to a configuration in which the connecting member 400 entirely overlaps the seal ring 150 in a top view. As a result, it is also possible to suppress variations in the in-plane temperature distribution of the substrate W supported by the seal ring 150.

[0060] If Joule heat is generated in the connecting member 400, the connecting member 400 will thermally expand while remaining sandwiched between the dielectric substrate 100 and the base plate 200. At this time, the bottom surface 162 of the first recess 160 (see FIG. 3 ) will be subjected to a force from the connecting member 400, which may cause a portion of the dielectric substrate 100 to deform so as to become convex toward the substrate W. If the connecting member 400 and the seal ring 150 overlap each other in top view, the above-mentioned deformation will occur at the position of the seal ring 150, and therefore the substrate W supported by the seal ring 150 may also deform.

[0061] However, in this embodiment, the connecting member 400 and the seal ring 150 do not overlap each other in a top view. Therefore, deformation of the dielectric substrate 100 due to thermal expansion of the connecting member 400 does not occur at the position of the seal ring 150, but occurs at a part of the bottom surface 116. Since the bottom surface 116 and the substrate W are spaced apart from each other, deformation of the substrate W is suppressed to a negligible level. Thus, the configuration of this embodiment can achieve not only the effect of suppressing variations in the in-plane temperature distribution of the substrate W, but also the secondary effect of suppressing deformation of the substrate W.

[0062] As described above, in this embodiment, all of the connection members 400 are disposed in positions that do not overlap the seal rings 150 in top view. However, in cases where local temperature changes in the seal rings 150 are not a problem, instead of the above-described configuration, a configuration may be adopted in which some of the connection members 400 overlap the seal rings 150 in whole or in part in top view.

[0063] 2, the connecting members 400 of this embodiment are all disposed at positions that do not overlap with either the seal rings 150 or the dots 113 in top view. In other words, there are no parts (specifically, the seal rings 150 and the dots 113) that come into solid contact with the substrate W directly above the connecting members 400, which can serve as heating or cooling sources. This makes it possible to further suppress local temperature changes and local deformations of the substrate W directly above the connecting members 400.

[0064] In this embodiment, the multiple connecting members 400 are arranged in a ring shape along the second seal ring 152 in a top view. The positional relationship between the connecting members 400 and the second seal ring 152 in a top view is generally the same for all connecting members 400, which makes it possible to further uniform the in-plane temperature distribution of the substrate W in the circumferential direction. In order to further uniformize the in-plane temperature distribution of the substrate W, in this embodiment, the multiple connecting members 400 are arranged in a ring shape and at equal intervals along the second seal ring 152 in a top view.

[0065] In the present embodiment, all of the connecting members 400 provided on the electrostatic chuck 10 are arranged in a circular shape at equal intervals when viewed from above. Instead of this configuration, some of the connecting members 400 may be arranged in positions different from those described above. In other words, only some of the connecting members 400 may be arranged in a circular shape at equal intervals.

[0066] As described above, the group of dots 113A is arranged at a position closest to the first seal ring 151 from the inside, and is arranged so as to be lined up in a ring shape along the first seal ring 151. Similarly, the group of dots 113B is arranged at a position closest to the second seal ring 152 from the inside, and is arranged so as to be lined up in a ring shape along the second seal ring 152. In other words, in this embodiment, the connecting member 400, the dots 113A, and the dots 113B are each arranged so as to be lined up in a ring shape along the seal ring 150.

[0067] However, the radial positions of the respective components are different from each other. The "radial position" refers to the distance from the center of the dielectric substrate 100 in a top view. More specifically, it refers to the distance from the center of the dielectric substrate 100 to the center of the connecting member 400, etc. in a top view.

[0068] The radial position of each dot 113A is outward from the radial position of the connecting member 400. Furthermore, the radial position of each dot 113B is inward from the radial position of the connecting member 400. In this embodiment, there are no dots 113 that are positioned at the same radial position as the connecting member 400. With this configuration, it is possible to ensure that the distance between the dots 113 and the connecting member 400 in a top view is large enough to prevent heat transfer to the substrate W via the dots 113 from becoming a problem.

[0069] In this embodiment, the centers of the plurality of connecting members 400 provided on the electrostatic chuck 10 are all disposed 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 portion of the dielectric substrate 100.

[0070] 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 connecting 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.

[0071] 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. The gas holes 114 are intended to supply 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. In the electrostatic chuck 10 of this embodiment, by arranging the gas holes 114, which can serve as a cooling source, near the connecting member 400, which can serve as a heating source, the in-plane temperature distribution of the substrate W during processing can be made more uniform.

[0072] In this embodiment, the connecting member 400 and the gas holes 114 are arranged alternately in the circumferential direction in the portion between the first seal ring 151 and the second seal ring 152. Furthermore, the gas holes 114 arranged in this portion are all arranged so that their centers, as viewed from above, are located on the dashed-dotted line DL. That is, the connecting member 400 and the gas holes 114 are arranged in a line in a circular shape as viewed from above. In this configuration, the distance between the connecting member 400 and the gas holes 114 is reduced, thereby further enhancing the effect of uniforming the in-plane temperature distribution of the substrate W during processing.

[0073] A 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.

[0074] 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.

[0075] 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).

[0076] 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 its center 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.

[0077] In this embodiment, as in the first embodiment, the connection members 400 and the gas holes 114 are arranged alternately in the circumferential direction. Furthermore, the gas holes 114 arranged in the relevant portion are all arranged so that their centers in a top view are located on the dashed-dotted line DL. In other words, the connection members 400 and the gas holes 114 are arranged in a line in a ring shape in a top view.

[0078] As described above, the arrangement of the connection members 400, etc., arranged in a "ring-like" configuration includes not only the arrangement in which the entire connection members 400, etc., are arranged in a ring-like configuration as in the first embodiment, but also the arrangement in which some of the connection members 400, etc., are arranged in a linear configuration as in this embodiment. The above configuration also achieves the same effects as those described in the first embodiment.

[0079] A third 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.

[0080] 6 is a top view of a portion of the dielectric substrate 100 according to this embodiment. This embodiment differs from the first embodiment only in the position of the connection member 400 when viewed from above.

[0081] The dashed-dotted line DL1 shown in Fig. 6 is an imaginary line drawn at the same position as the dashed-dotted line DL shown in Fig. 2 (first embodiment). Of the gas holes 114, those formed in the portion between the first seal ring 151 and the second seal ring 152 are arranged so that the center position of each gas hole 114 is on the dashed-dotted line DL1 in top view.

[0082] The dashed-dotted line DL2 shown in Fig. 6 is a virtual line extending parallel to the second seal ring 152, similar to the dashed-dotted line DL1. In top view, the dashed-dotted line DL2 is circular, and its center coincides with the center of the dielectric substrate 100 or the base plate 200. The dashed-dotted line DL2 is a circle that is slightly larger than the outer shape of the second seal ring 152 and slightly smaller than the dashed-dotted line DL1. The connecting members 400 are arranged so that the center position of each connecting member 400 is located on the dashed-dotted line DL2 in top view. In other words, the configuration of this embodiment can be said to be a configuration in which each connecting member 400 is slightly shifted inward from the configuration of the first embodiment shown in Fig. 2.

[0083] In the present embodiment, a portion of each of the connection members 400 overlaps with the second seal ring 152 when viewed from above. However, the center of each of the connection members 400 does not overlap with the second seal ring 152, and is located outside the second seal ring 152.

[0084] That is, in this embodiment, when focusing on any one of the connection members 400, only a portion of the connection member 400 overlaps with the seal ring 150 in top view. The remaining portion of the connection member 400, including the center thereof, does not overlap with the seal ring 150 in top view. Even in this embodiment, it is possible to suppress to some extent the variation in the in-plane temperature distribution of the substrate W during processing.

[0085] In this way, only a portion of the connecting member 400, including its center, may be arranged in a position that does not overlap with the seal ring 150 in top view. However, in order to sufficiently suppress variations in the in-plane temperature distribution of the substrate W, it is preferable to arrange the entire connecting member 400, rather than just a portion of it, in a position that does not overlap with the seal ring 150 in top view, as in the first embodiment.

[0086] In this embodiment, similarly to the first embodiment, the connection members 400 and the gas holes 114 are arranged alternately in the circumferential direction.

[0087] In this way, the arrangement in which the connecting members 400 and the gas holes 114 are arranged "alternately in the circumferential direction" includes not only an arrangement in which the connecting members 400 and the gas holes 114 are arranged in a row on the same dashed-dotted line DL, but also an arrangement in which the gas holes 114 are arranged in a row on the dashed-dotted line DL1 and the connecting members 400 are arranged in a row on the dashed-dotted line DL2. Even with the above configuration, the same effects as those described in the first embodiment are achieved.

[0088] A fourth 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.

[0089] Fig. 7 illustrates the configuration of the electrostatic chuck 10 according to this embodiment from the same perspective as Fig. 3. As shown in Fig. 7, 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.

[0090] 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 substantially the entire bottom surface 162. In this embodiment, the tip of the protrusion 420 is pressed against the metal plate 141.

[0091] 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.

[0092] 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 via 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.

[0093] 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.

[0094] 10: Electrostatic chuck 100: Dielectric substrate 110: Surface 113: Dot 114: Gas hole 140: RF electrode 150: Seal ring 151: First seal ring 152: Second seal ring 200: Base plate 400: Connecting member W: Substrate

Claims

1. An electrostatic chuck comprising: a dielectric substrate having a mounting surface on which an object to be attracted is placed; a seal ring which is an annular protrusion formed on said dielectric substrate and whose tip surface forms part of said mounting surface; an RF electrode provided inside said dielectric substrate; a base plate made of metal and joined to said dielectric substrate; and a connecting member which electrically connects between said RF electrode and said base plate, wherein when viewed from a direction perpendicular to said mounting surface, at least a portion of said connecting member is positioned so as not to overlap with said seal ring.

2. An electrostatic chuck as set forth in claim 1, characterized in that, when viewed from a direction perpendicular to the mounting surface, the connecting member is positioned so that its center does not overlap with the seal ring.

3. An electrostatic chuck as set forth in claim 2, characterized in that, when viewed from a direction perpendicular to the mounting surface, the connecting member is positioned so that it does not entirely overlap the seal ring.

4. An electrostatic chuck as described in claim 1, further comprising a plurality of circular protrusions formed on the dielectric substrate, the tip surfaces of which form part of the mounting surface, and wherein, when viewed from a direction perpendicular to the mounting surface, the connecting member is positioned such that at least a portion of it does not overlap either the seal ring or the dots.

5. The electrostatic chuck according to claim 4, wherein, when viewed from a direction perpendicular to the mounting surface, the plurality of connecting members are arranged in a ring shape along the seal ring.

6. An electrostatic chuck according to claim 5, characterized in that, when viewed from a direction perpendicular to the mounting surface, a plurality of said connecting members are arranged in a circular shape and at equal intervals along said seal ring.

7. An electrostatic chuck as set forth in claim 5, characterized in that, when viewed from a direction perpendicular to the mounting surface, the dots are arranged in a ring shape along the seal ring, and the radial position of each of the connecting members arranged in a ring is different from the radial position of each of the dots arranged in a ring.

8. The electrostatic chuck described in claim 5, characterized in that the seal rings include a first seal ring arranged at the outermost position of the mounting surface, and a second seal ring arranged at a position inside the first seal ring without any other seal rings sandwiched between them, and when viewed from a direction perpendicular to the mounting surface, all of the multiple connecting members are arranged at a position where their centers are between the first seal ring and the second seal ring.

9. The electrostatic chuck according to claim 8, characterized in that, when viewed from a direction perpendicular to the mounting surface, a plurality of gas holes are formed in the portion of the dielectric substrate between the first seal ring and the second seal ring.

10. The electrostatic chuck according to claim 9, wherein, when viewed from a direction perpendicular to the mounting surface, the connecting members and the gas holes are arranged alternately in the circumferential direction.

11. The electrostatic chuck according to claim 10, wherein the connecting member and the gas holes are arranged in a ring shape and aligned in a line when viewed from a direction perpendicular to the mounting surface.

12. The electrostatic chuck of claim 1, wherein the seal rings include a first seal ring arranged at the outermost position of the mounting surface, and a second seal ring arranged at a position inside the first seal ring without any other seal rings sandwiched between them, and wherein when viewed from a direction perpendicular to the mounting surface, the shape of the connecting member is circular, and the diameter of the connecting member is smaller than the distance between the first seal ring and the second seal ring.

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