Electrostatic chuck

Abstract

Provided is an electrostatic chuck capable of suppressing variation in in-plane temperature distribution in a substrate during processing. An electrostatic chuck 10 comprises: a 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 connection members 400 electrically connecting the RF electrode 140 and the base plate 200. A plurality of gas holes 114 are formed in the dielectric substrate 100. A distribution flow path 240 for distributing gas to the plurality of gas holes 114 is formed in the base plate 200. In a top view, the connection members 400 are disposed at positions where at least portions thereof do not overlap the distribution flow path 240.

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] 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.

[0004] International Publication No. 2022 / 255118

[0005] 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.

[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.

[0009] In order to solve the above problems, the 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, a base plate made of metal and joined to the dielectric substrate, and a connecting member that electrically connects the RF electrode and the base plate. A plurality of gas holes are formed in the dielectric substrate. The base plate is formed with distribution channels for distributing gas to the plurality of gas holes. 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 distribution channels.

[0010] In the electrostatic chuck having the above-described configuration, there is no distribution flow path that could cause thermal resistance directly below at least a portion of the connecting member. With this configuration, heat generated in the connecting member is efficiently collected by the base plate, thereby suppressing variations in the in-plane temperature distribution of the substrate during processing.

[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.

[0012] 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 view showing the configuration of a coolant flow path formed inside a base plate. FIG. 4 is a view showing the configuration of a distribution flow path formed inside a base plate. FIG. 5 is a cross-sectional view showing in detail the configuration of a connecting member and its surrounding parts of the electrostatic chuck according to the first embodiment. FIG. 6 is a perspective view showing the configuration of the connecting member. FIG. 7 is a view for explaining the positional relationship between the distribution flow path and the connecting member, etc. of the electrostatic chuck according to the first embodiment. FIG. 8 is a view for explaining the positional relationship between the coolant flow path and the connecting member, etc. of the electrostatic chuck according to the first embodiment. FIG. 9 is a view for explaining the positional relationship between the distribution flow path and the connecting member, etc. of the electrostatic chuck according to the second embodiment. FIG. 10 is a cross-sectional view showing in detail the configuration of a connecting member and its surrounding parts of an electrostatic chuck according to a third embodiment.

[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 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.

[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 is made of, for example, high-purity aluminum oxide (Al ２ O ３The 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 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.

[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 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.

[0020] 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.

[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] 1, a space SP is formed between the dielectric substrate 100 and the substrate W. When processing 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. 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 mounting surface 110, 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" hereinafter. The seal ring 150 disposed on the inside will also be referred to as the "second seal ring 152" hereinafter.

[0026] 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 any other seal rings 150 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 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.

[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" 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.

[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 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] 1 and 2, a plurality of gas holes 114 are formed in the dielectric substrate 100. The gas holes 114 are holes for supplying helium gas to the space SP, and are circular through-holes formed to extend perpendicularly to the surface 110. Helium gas supplied from the outside passes through gas flow paths formed inside the base plate 200 and is then supplied to the space SP through each of the gas holes 114. The specific configuration of the above-mentioned "gas flow paths" will be described later.

[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] 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.

[0034] 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.

[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 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.

[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 the 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 then discharged to the outside together with the coolant. The coolant is supplied to and discharged from the coolant flow path 250 through openings 251 and 252 (not shown in FIG. 1 , see FIG. 3 ) formed in a surface 220 of the base plate 200 opposite the surface 210.

[0038] 3 is a schematic top view of the configuration of the coolant flow path 250 formed inside the base plate 200. As described above, openings 251 and 252 are provided on the surface 220 of the base plate 200. The coolant flow path 250 connects the openings 251 and 252 and is formed along a path that passes through almost the entire base plate 200 in the top view. Most of the coolant flow path 250 is formed to extend along an arc that is concentric with the circular base plate 200.

[0039] Both openings 251 and 252 are circular openings when viewed from above, and are formed to extend perpendicularly to surface 220 from surface 220 toward coolant flow path 250. The internal spaces of openings 251 and 252 can also be considered as part of coolant flow path 250. In this embodiment, a coolant is supplied from the outside to opening 251. The coolant that has passed through coolant flow path 250 and is used to cool the substrate W is discharged to the outside through opening 252.

[0040] Continuing the explanation, returning to FIG. 1 , supply channels 214 are formed in the base plate 200. The supply channels 214 are holes formed to extend in a direction perpendicular to the surface 110, which is the mounting surface, and extend from the surface 210 to distribution channels 240, which will be described later. The supply channels 214 are formed at positions that overlap with the gas holes 114 in a top view, and are connected to the gas holes 114 via through holes provided in the bonding layer 300. The supply channels 214, together with the gas holes 114 of the dielectric substrate 100, form part of a channel for supplying helium gas toward the space SP on the mounting surface side.

[0041] A porous body made of, for example, alumina may be disposed inside the supply flow path 214. With this configuration, it is possible to suppress the occurrence of dielectric breakdown in the path through the supply flow path 214 and the gas hole 114 while ensuring the flow of gas in the supply flow path 214.

[0042] A distribution channel 240 is formed inside the base plate 200. The distribution channel 240 is a channel for distributing helium gas to each of the supply channels 214 and the gas holes 114 connected thereto. The distribution channel 240 is routed parallel to the surface 210 and connected to the lower ends of each of the supply channels 214.

[0043] 4 schematically illustrates the configuration of the distribution flow paths 240 inside the base plate 200, the supply flow paths 214 connected thereto, and the like. The arrows in FIG. 4 indicate the flow of helium gas. The portion marked with the reference symbol "241" in FIG. 4 indicates a helium gas flow path formed in the base plate 200 to guide helium gas supplied from the outside to the distribution flow paths 240. This flow path will also be referred to as the "flow path 241" below. One end of the flow path 241 is connected to the distribution flow path 240. The other end of the flow path 241 opens at the surface 220 of the base plate 200.

[0044] As shown in FIG. 4 , in this embodiment, the multiple supply channels 214 are arranged in a circular pattern in a top view. The distribution channels 240 are routed in a circular pattern so as to pass directly below each of the supply channels 214 in a top view. The lower ends of each of the supply channels 214 are connected to the distribution channels 240. Therefore, helium gas supplied from the outside is supplied to the distribution channels 240 through the channels 241 and distributed from the distribution channels 240 to each of the supply channels 214. The helium gas is then supplied from each of the supply channels 214 to the space SP through the gas holes 114 located directly above them. By forming the distribution channels 240 inside the base plate 200, the number of portions (i.e., channels 241) that receive helium gas from the outside can be reduced.

[0045] In this embodiment, a plurality of gas flow paths are provided as shown in Fig. 4. Specifically, a plurality of distribution flow paths 240 having different diameters in a top view are provided in the base plate 200, and these are arranged concentrically in a top view. The plurality of gas holes 114 shown in Fig. 2 are connected to one of the distribution flow paths 240 and receive a supply of helium gas from the distribution flow path 240.

[0046] As described above, the base plate 200 has a relatively complex internal structure, including the refrigerant flow paths 250, the distribution flow paths 240, and the supply flow paths 214. To facilitate the formation of the refrigerant flow paths 250, the base plate 200 of this embodiment is formed by joining multiple members. As shown in FIG. 1 , the base plate 200 is formed by joining together three members, namely, a first member 201, a second member 202, and a third member 203. The members are joined by welding, but may also be joined by other methods such as brazing or fastening. The number of members constituting the base plate 200 may be four or more, or may be two.

[0047] The first member 201, the second member 202, and the third member 203 are arranged in this order along a direction perpendicular to the surface 110, which is the mounting surface. The first member 201 is the part of the members constituting the base plate 200 that is closest to the dielectric substrate 100. The surface 210 mentioned above is a part of the first member 201. The third member 203 is the part of the members constituting the base plate 200 that is on the opposite side from the dielectric substrate 100. The surface 220 mentioned above is a part of the third member 203. The second member 202 is a member that is between the first member 201 and the third member 203.

[0048] A joint boundary B1 between the first member 201 and the second member 202 is parallel to the surface 110 and the surface 210. A joint boundary B2 between the second member 202 and the third member 203 is also parallel to the surface 110 and the surface 210.

[0049] 1 , in this embodiment, the distribution channels 240 and the supply channels 214 are both entirely formed in the first member 201. The distribution channels 240 are annular grooves that are formed in advance along the surface of the first member 201 that will become the joining boundary B1 before the respective members are joined. In this manner, by forming the grooves in advance in the surface of the first member 201 and then joining the second member 202 so as to cover the surface, the distribution channels 240 that follow the grooves can be easily formed inside the base plate 200. Note that the grooves that will become the distribution channels 240 may be formed not in the surface of the first member 201 but in the surface of the second member 202 that will become the joining boundary B1.

[0050] 1 , the coolant flow path 250 in this embodiment is entirely formed in the second member 202. The coolant flow path 250 is a groove that is formed in advance along the surface of the second member 202 that will become the joining boundary B2 before the respective members are joined. In this way, by forming the groove in advance in the surface of the second member 202 and then joining the third member 203 so as to cover this surface, the coolant flow path 250 that follows the groove can be easily formed inside the base plate 200. Note that the groove that will become the coolant flow path 250 may also be formed in the surface of the second member 202 that will become the joining boundary B1.

[0051] The specific configuration of the connecting member 400 and its surrounding area will be described with reference to FIG. 5 and other figures. As shown in FIG. 5 , 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.

[0052] 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 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. A bottom surface 262 of the second recess 260 is located closer to the surface 210 than the distribution channel 240.

[0053] 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.

[0054] The member marked with the reference numeral "310" in FIG. 5 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.

[0055] 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.

[0056] 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.

[0057] 6, 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."

[0058] 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.

[0059] 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.

[0060] 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. 6. 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).

[0061] 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.

[0062] The shape of the connection member 400 may be different from that shown in Fig. 6. For example, the entire connection member 400 may be substantially cylindrical, and may not have the protrusion 420.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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. Each of the gas holes 114 arranged in this portion is arranged so that its center, as viewed from above, is slightly inside the dashed-dotted line DL. The distribution flow paths 240 described above are arranged directly below each gas hole 114 (toward the back of the paper in FIG. 2).

[0068] 7 is a schematic top view illustrating the positional relationship between the multiple distribution channels 240 provided inside the base plate 200 and the connection member 400 and the gas holes 114. Each gas hole 114 is provided at a position where its entirety overlaps with the distribution channel 240 in top view.

[0069] In this embodiment, all of the multiple connection members 400 are disposed at positions further outside than the outermost distribution flow path 240, and are disposed so as to be lined up in a ring shape along the distribution flow path 240. As a result, each connection member 400 is disposed at a position where it does not entirely overlap with the distribution flow path 240 in top view.

[0070] Incidentally, when a substrate W is being processed in a semiconductor manufacturing apparatus, 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.

[0071] In this way, the connecting member 400 can serve as a heat source for the dielectric substrate 100 and the substrate W. Therefore, depending on the position of the connecting member 400, there is a possibility that the in-plane temperature distribution of the substrate W during processing may vary too much.

[0072] For example, if the distribution flow path 240 is provided at a position directly below the connection member 400, the distribution flow path 240 may act as a thermal resistance, hindering heat transfer between the connection member 400 and the refrigerant flow path 250. As a result, the heat generated in the connection member 400 may not be efficiently collected, and a local temperature rise may occur directly above the connection member 400.

[0073] Therefore, in the electrostatic chuck 10 according to this embodiment, the connection members 400 are arranged at positions that do not overlap with the distribution channels 240 when viewed from above. In such a configuration, heat generated in the connection members 400 is efficiently collected by the base plate 200, thereby suppressing variations in the in-plane temperature distribution of the substrate W during processing.

[0074] Each connection member 400 is disposed in a position where it does not entirely overlap with the distribution flow path 240 in top view. In other words, when focusing on any one connection member 400, that connection member 400 does not overlap with the distribution flow path 240 at all in top view. Because the distribution flow path 240 is not interposed between the connection member 400 and the refrigerant flow path 250, heat generated in the connection member 400 can be recovered more efficiently.

[0075] When focusing on any one connecting member 400, the portion of the connecting member 400 that is arranged in a position that does not overlap with the distribution flow path 240 in top view may be the entire connecting member 400 as in the present embodiment, or may be only a part of the connecting member 400. In other words, the connecting member 400 may be configured so that it partially overlaps with the distribution flow path 240. However, in order to efficiently recover heat generated in the connecting member 400, it is preferable that the portion of the connecting member 400 that does not overlap with the distribution flow path 240 is as large as possible. It is preferable that at least the center of the connecting member 400 is arranged in a position that does not overlap with the distribution flow path 240 in top view.

[0076] In the present embodiment, all of the multiple connecting members 400 provided in the electrostatic chuck 10 are arranged at positions that do not entirely overlap with the distribution flow path 240, as described above. Instead of this configuration, some of the connecting members 400 may be arranged at positions different from the above. That is, only some of the multiple connecting members 400 may be arranged at positions that do not overlap with the distribution flow path 240 in a top view. However, in order to efficiently recover heat generated in the connecting members 400, it is preferable that all of the connecting members 400 are arranged at positions that do not at least partially overlap with the distribution flow path 240.

[0077] In this embodiment, all of the multiple connecting members 400 provided in the electrostatic chuck 10 are arranged in a ring shape along the distribution flow path 240 in a top view. In this configuration, the positional relationship between the connecting members 400 and the distribution flow path 240 is uniform throughout, making it possible to further uniformize the in-plane temperature distribution of the substrate W during processing. 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 multiple connecting members 400 may be arranged in a ring shape along the distribution flow path 240.

[0078] 8 illustrates a portion of the refrigerant flow path 250 and the distribution flow path 240 in a top view, and also illustrates a connecting member 400 and a gas hole 114 disposed directly above them. The diameter D1 of the connecting member 400 in a top view is smaller than the width D3 of the refrigerant flow path in a top view. The diameter D1 of the connecting member 400 in a top view is also smaller than the width D4 of the distribution flow path 240 in a top view.

[0079] 8, the distribution flow path 240 is provided at a position overlapping the refrigerant flow path 250 in a top view. When the distribution flow path 240 is provided at such a position, the distribution flow path 240 is likely to become a thermal resistance, and therefore, the above-described configuration, in which the connection member 400 is disposed at a position that does not overlap the distribution flow path 240 in a top view, is particularly effective. Note that the portion of the distribution flow path 240 that is provided at a position overlapping the refrigerant flow path 250 in a top view may be the entire distribution flow path 240, or only a portion thereof.

[0080] 8 , the connection members 400 are disposed at positions where they entirely overlap the refrigerant flow paths 250 in a top view. In other words, when focusing on any one connection member 400, the entire connection member 400 overlaps the refrigerant flow paths 250 in a top view. In this configuration, the refrigerant flow paths 250 are located directly below the connection members 400, which are heat sources, without passing through the distribution flow paths 240. Therefore, heat from the connection members 400 can be collected more efficiently by the refrigerant flow paths 250.

[0081] When focusing on any one connection member 400, the portion of the connection member 400 that overlaps with the refrigerant flow path 250 in a top view may be the entire connection member 400 as in this embodiment, or may be only a part of the connection member 400. In other words, the connection member 400 may partially overlap with the refrigerant flow path 250. However, in order to efficiently recover heat generated in the connection member 400, it is preferable that the portion of the connection member 400 that overlaps with the refrigerant flow path 250 be as large as possible. It is preferable that the connection member 400 be positioned so that at least its center overlaps with the refrigerant flow path 250 in a top view.

[0082] In the present embodiment, all of the multiple connecting members 400 provided in the electrostatic chuck 10 are disposed at positions overlapping the coolant flow path 250 in a top view and are arranged in a ring shape along the coolant flow path 250. Instead of this configuration, some of the connecting members 400 may be disposed at positions different from the above. In other words, only some of the multiple connecting members 400 may be arranged in a ring shape and at least partially overlapping the coolant flow path 250.

[0083] 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.

[0084] 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.

[0085] 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 .

[0086] 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.

[0087] 9 schematically shows, in a top view, the positional relationship between the distribution flow passages 240, the connecting members 400, and the gas holes 114 in this embodiment. The dashed-dotted line DL shown in FIG. 9 is an imaginary line drawn at the same position as the dashed-dotted line DL shown in FIG. 2 (first embodiment). Each connecting member 400 is disposed so that its center is positioned on the dashed-dotted line DL in a top view. In this embodiment, too, each connecting member 400 is disposed at a position that does not overlap with the distribution flow passages 240 in a top view.

[0088] In this embodiment, the gas holes 114 are expanded in diameter inside the dielectric substrate 100. The expanded portion of the gas holes 114 is hereinafter also referred to as the "expanded portion 114A." In Fig. 9, the portion of the gas holes 114 that opens on the surface 110 side of the dielectric substrate 100 is depicted by a solid line, and the expanded portion 114A below it (toward the back of the paper in Fig. 9) is depicted by a dotted line.

[0089] Each gas hole 114 is arranged so that the center of its opening on the surface 110 is located on the dashed line DL in top view. The opening does not overlap with the distribution flow path 240 in top view. However, because the distribution flow path 240 and a portion of the expanded diameter section 114A overlap each other in top view, helium gas flows from the distribution flow path 240 into each expanded diameter section 114A and is guided from the gas hole 114 to the space SP.

[0090] In this embodiment, the openings of the gas holes 114 on the surface 110 side and the connecting member 400 are arranged in a ring shape and in a line when viewed from above. Even in this embodiment, the same effects as those described in the first embodiment are achieved.

[0091] 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.

[0092] Fig. 10 illustrates the configuration of the electrostatic chuck 10 according to this embodiment from the same perspective as Fig. 5. As shown in Fig. 10, 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 10: Electrostatic chuck 100: Dielectric substrate 110: Surface 114: Gas hole 140: RF electrode 200: Base plate 240: Distribution channel 250: Coolant channel 400: Connection 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; an RF electrode provided inside the dielectric substrate; a base plate made of metal and joined to the dielectric substrate; and a connecting member that electrically connects the RF electrode and the base plate, wherein a plurality of gas holes are formed in the dielectric substrate, and distribution channels are formed in the base plate for distributing gas to the plurality of gas holes, and wherein, when viewed in a direction perpendicular to the mounting surface, at least a portion of the connecting member is positioned so as not to overlap with the distribution channels.

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 distribution flow path.

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 its entirety does not overlap with the distribution flow path.

4. The electrostatic chuck according to claim 1, characterized in that, when viewed from a direction perpendicular to the mounting surface, the plurality of connecting members are arranged in a ring shape along the distribution flow path.

5. An electrostatic chuck as described in claim 1, characterized in that a coolant flow path through which a coolant passes is formed inside the base plate, and when viewed from a direction perpendicular to the mounting surface, the distribution flow path is located at a position overlapping the coolant flow path.

6. The electrostatic chuck according to claim 1, wherein a coolant flow path through which a coolant passes is formed inside the base plate, and 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 overlaps with the coolant flow path.

7. The electrostatic chuck according to claim 1, wherein the shape of the connecting member is circular when viewed from a direction perpendicular to the mounting surface, and the diameter of the connecting member is smaller than the width of the distribution flow path.

8. The electrostatic chuck according to claim 1, wherein a coolant flow path through which a coolant passes is formed inside the base plate, the shape of the connecting member is circular when viewed in a direction perpendicular to the mounting surface, and the diameter of the connecting member is smaller than the width of the coolant flow path.

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