electrostatic chuck

Abstract

The present invention provides an electrostatic chuck capable of suppressing variations in the in-plane temperature distribution of a substrate during processing. [Solution] The electrostatic chuck 10 comprises a dielectric substrate 100, a seal ring 150 which is an annular projection formed on the dielectric substrate 100, an RF electrode 140 provided inside the dielectric substrate 100, a base plate 200 made of metal and bonded to the dielectric substrate 100, and a connecting member 400 which electrically connects the RF electrode 140 and the base plate 200. In a top view, the connecting member 400 is positioned so that at least a part of it does not overlap with the seal ring 150.

Description

Technical Field

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

Background Art

[0002] For example, in a semiconductor manufacturing apparatus such as an etching apparatus, an electrostatic chuck is provided as a device for adsorbing and holding a substrate such as a silicon wafer to be processed. The electrostatic chuck includes a dielectric substrate provided with an adsorption electrode and a base plate for supporting the dielectric substrate, and these are joined to each other. When a voltage is applied to the adsorption electrode, an electrostatic force is generated, and the substrate placed on the dielectric substrate is adsorbed and held.

[0003] On the mounting surface side of the dielectric substrate, an annular protrusion called a "seal ring" and a minute circular protrusion called a "dot" are often formed. The substrate is adsorbed and held in a state of abutting against the tips of the seal ring and the dot.

[0004] As described in Patent Document 1 below, the 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 the base plate are electrically connected via a conductive connecting member. Thereby, the potential of the RF electrode during the processing of the substrate is maintained at the potential of the base plate (for example, the ground potential).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] To electrically connect the above-mentioned connecting member and the RF electrode, for example, a recess can be formed on the base plate side of the dielectric substrate, the RF electrode can be exposed at its bottom, and the connecting member can be housed inside the recess. To electrically connect the RF electrode and the base plate via the connecting member, for example, a recess can be formed on the dielectric substrate side of the base plate, and the connecting member can be housed inside the recess. The connecting member will be sandwiched between the dielectric substrate and the base plate.

[0007] Incidentally, the thermal conductivity of the connecting material is relatively high. Therefore, the portion of the dielectric substrate directly above the connecting material may be locally overcooled due to heat transfer to the base plate via the connecting material.

[0008] Furthermore, when substrates are being processed in semiconductor manufacturing equipment, Joule heating is generated in the connecting components due to the application of AC voltage to the RF electrodes. Depending on the amount of heat generated by the connecting components, the portion of the dielectric substrate directly above the connecting components may be locally overheated by the heat from the connecting components.

[0009] Thus, the connecting member can act as either a heating source or a cooling source for the dielectric substrate. Therefore, depending on the position of the connecting member, the variation in the in-plane temperature distribution of the substrate during processing may become too large.

[0010] The present invention has been made in view of these problems, and its objective is to provide an electrostatic chuck that can suppress variations in the in-plane temperature distribution of a substrate during processing. [Means for solving the problem]

[0011] To solve the above problems, the electrostatic chuck according to the present invention comprises a dielectric substrate having a mounting surface on which an object to be adsorbed is placed, a seal ring which is an annular projection formed on the dielectric substrate and whose tip surface is part of the mounting surface, an RF electrode provided inside the dielectric substrate, a base plate made of metal and bonded 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 part of it does not overlap with the seal ring.

[0012] In the electrostatic chuck with the above configuration, localized temperature rises or drops occurring in the seal ring can be suppressed compared to a configuration where the entire connecting member overlaps the seal ring in a top view. As a result, variations in the in-plane temperature distribution of the substrate supported by the seal ring can also be suppressed. [Effects of the Invention]

[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. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic cross-sectional view showing the configuration of the electrostatic chuck according to the first embodiment. [Figure 2] This figure shows the configuration of the mounting surface side of the dielectric substrate equipped with the electrostatic chuck shown in Figure 1. [Figure 3] This is a cross-sectional view showing in detail the configuration of the connecting member and its vicinity in the electrostatic chuck according to the first embodiment. [Figure 4] This is a perspective view showing the configuration of the connecting members. [Figure 5] This figure shows the configuration of the mounting surface side of the dielectric substrate according to the second embodiment. [Figure 6] This figure shows the configuration of the mounting surface side of the dielectric substrate according to the third embodiment. [Figure 7]It is a cross-sectional view showing in detail the configuration of a connection member and its vicinity of an electrostatic chuck according to the fourth embodiment.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, this embodiment will be described with reference to the accompanying drawings. For ease of understanding of the description, the same reference numerals are attached to the same components in each drawing as much as possible, and duplicate descriptions are omitted.

[0016] The first embodiment will be described. The electrostatic chuck 10 according to this embodiment adsorbs and holds a substrate W to be processed by electrostatic force inside a semiconductor manufacturing apparatus (not shown) such as an etching apparatus. The substrate W to be adsorbed is, for example, a silicon wafer. The electrostatic chuck 10 may be used in an apparatus other than a semiconductor manufacturing apparatus.

[0017] FIG. 1 schematically shows a cross-sectional view of the configuration of the electrostatic chuck 10 in a state where the substrate W is adsorbed and held. 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 ceramic sintered body. The dielectric substrate 100 contains, for example, high-purity aluminum oxide (Al2O3), but may contain other materials. The purity, type, additives, etc. of the ceramics in the dielectric substrate 100 can be appropriately set in consideration of the plasma resistance required for the dielectric substrate 100 in a semiconductor manufacturing apparatus.

[0019] Of the dielectric substrate 100, the upper surface 110 in FIG. 1 is the "mounting surface" on which the substrate W is placed. Also, the lower surface 120 of the dielectric substrate 100 in FIG. 1 is the "bonding surface" that is bonded to the base plate 200 via the bonding layer 300. The viewpoint when looking at the electrostatic chuck 10 from the surface 110 side along the direction perpendicular to the surface 110 will also be referred to as "top view" hereinafter.

[0020] An adsorption electrode 130 is embedded inside the dielectric substrate 100. The adsorption electrode 130 is a thin flat plate-like layer formed of a metal material such as tungsten, for example, and is arranged parallel to the surface 110. As the material of the adsorption electrode 130, in addition to tungsten, molybdenum, platinum, palladium, etc. may also be used. When a voltage is applied to the adsorption electrode 130 from the outside through a power supply path (not shown), an electrostatic force is generated between the surface 110 and the substrate W, whereby the substrate W is adsorbed and held. As the configuration of the power supply path, various known configurations can be adopted. The adsorption electrode 130 may be provided only one as a so-called "unipolar" electrode as in the present embodiment, or may be provided two as a so-called "bipolar" electrode.

[0021] Inside the dielectric substrate 100, in addition to the above-described adsorption electrode 130, an RF electrode 140 is also embedded. The RF electrode 140 is provided as one of a pair of opposing electrodes for generating plasma in a semiconductor manufacturing apparatus. The other of the opposing electrodes is provided at a position above the electrostatic chuck 10 in the semiconductor manufacturing apparatus. When a high-frequency alternating voltage is applied between these opposing electrodes, plasma is generated above the substrate W and is used for processes such as film formation and etching on the substrate W.

[0022] The RF electrode 140 is, like the adsorption electrode 130, a thin flat plate-like layer formed of a metal material such as tungsten, for example. As the material of the RF electrode 140, in addition to tungsten, molybdenum, platinum, palladium, etc. may also be used. The RF electrode 140 is embedded at a position closer to the surface 120 side than the adsorption electrode 130. The RF electrode 140 is arranged parallel to the surface 110, like the adsorption electrode 130. The RF electrode 140 is a single electrode that is substantially circular in a top view. The center of the RF electrode 140 in the 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 the base plate 200, which will be described later. Due to the connecting member 400, the potential of the RF electrode 140 during processing of the substrate W becomes the same as the potential of the base plate 200. In Figure 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 Figure 1, a space SP is formed between the dielectric substrate 100 and the substrate W. When etching or other processes are performed in the semiconductor manufacturing apparatus, helium gas for temperature control is supplied to the space SP from the outside through a gas hole 114 (not shown in Figure 1; see Figure 2). By interposing 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 gas supplied to the space SP for temperature control may be a different type of gas than helium.

[0025] Figure 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 described above is formed around them. Note that the dots 113 are not shown in Figure 1.

[0026] The seal ring 150 is an annular projection provided as a wall that partitions the space SP. Multiple seal rings 150 are provided and are arranged in a substantially concentric pattern when viewed from above. The tip surface of each seal ring 150 (the upper end surface in Figure 1) is part of the surface 110 and contacts 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 helium gas pressure in each space SP and make the surface temperature distribution of the substrate W during processing more uniform.

[0027] The outer seal ring 150 will also be referred to as the "first seal ring 151" below. The inner seal ring 150 will also be referred to as the "second seal ring 152" below.

[0028] The first seal ring 151 is a seal ring 150 positioned at the outermost edge of the mounting surface 110. The second seal ring 152 is a seal ring 150 positioned inside the first seal ring 151, without any other seal rings 150 in between. There may also be another seal ring 150 provided inside the second seal ring 152.

[0029] In Figures 1 and 2, the portion labeled "116" is the bottom surface of space SP. Hereafter, this portion will also be referred to as "bottom surface 116". The seal ring 150, along with the dot 113 described below, is formed as a result of excavating a portion of surface 110 down to the position of bottom surface 116.

[0030] The dots 113 are circular protrusions that extend from the bottom surface 116. As shown in Figure 2, multiple dots 113 are provided and are dispersed on the mounting surface of the dielectric substrate 100. The upper end surface of each dot 113 is part of the surface 110 and contacts the substrate W. By providing multiple such dots 113, the bending of the substrate W is suppressed.

[0031] Of the multiple dots 113, the group of dots 113 that are positioned closest to the first seal ring 151 from the inside and arranged in a ring along the first seal ring 151 will hereafter be referred to as "dot 113A". Also, of the multiple dots 113, the group of dots 113 that are positioned closest to the second seal ring 152 from the inside and arranged in a ring along the second seal ring 152 will hereafter be referred to as "dot 113B".

[0032] The dots 113 may be evenly distributed across the entire mounting surface of the dielectric substrate 100, or they may be arranged to be denser in some areas. In this embodiment, the arrangement density of the dots 113 in the outer peripheral portion is higher than that of the central portion when viewed from above. Specifically, the arrangement density of dots 113A and dots 113B is higher than that of the other dots 113. By arranging multiple dots 113 in this manner, the outer peripheral portion of the substrate W, which tends to become relatively hot, can be efficiently cooled, and variations in the in-plane temperature distribution of the substrate W can be suppressed.

[0033] As shown in Figure 2, the dielectric substrate 100 has a plurality of gas holes 114 formed therein. The gas holes 114 are not shown in Figure 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 surface 120 toward surface 110. The helium gas supplied from the outside passes through a gas channel (not shown) formed inside the base plate 200, and is then supplied to the space SP through each of the gas holes 114.

[0034] In this embodiment, multiple gas holes 114 are connected to each of the two divided spaces SP. A porous body made of, for example, alumina, may be placed inside the gas holes 114. With this configuration, it is possible to ensure gas flow in the gas holes 114 while suppressing the occurrence of dielectric breakdown along the path through the gas holes 114.

[0035] Grooves may be formed on the bottom surface 116 of the space SP for the purpose of increasing the in-plane diffusion rate of helium gas.

[0036] Returning to Figure 1, let's continue the explanation. The base plate 200 is a roughly disc-shaped member that supports the dielectric substrate 100. The base plate 200 is made of a metallic 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 it bonds the two together. The bonding layer 300 is made by curing an adhesive made of an insulating material. In this embodiment, a silicone adhesive is used as the adhesive. However, the bonding layer 300 may be made by curing another type of adhesive. In any case, it is preferable to use a material with the highest possible thermal conductivity for the bonding layer 300 so that the thermal resistance between the dielectric substrate 100 and the base plate 200 is reduced.

[0038] An insulating film may be formed on the surface of the base plate 200. As the insulating film, for example, an alumina film formed by thermal spraying can be used. By covering the surface of the base plate 200 with an insulating film, the dielectric strength of the base plate 200 can be increased.

[0039] A refrigerant channel 250 is formed inside the base plate 200 for passing a refrigerant. When etching or other processes are performed in the semiconductor manufacturing equipment, a refrigerant is supplied from the outside to the refrigerant channel 250, thereby cooling the base plate 200. During processing, the heat generated in the substrate W is transferred to the refrigerant 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 refrigerant. The supply and discharge of refrigerant to and from the refrigerant channel 250 is performed through an opening (not shown) formed on the surface 220 of the base plate 200 opposite to the surface 210.

[0040] The specific configuration of the connecting member 400 and its vicinity will be described with reference to Figure 3, etc. As shown in Figure 3, a first recess 160 is formed on the surface 120 of the dielectric substrate 100 on the base plate 200 side. The first recess 160 is a portion of the surface 120 that has been recessed toward the surface 110 side in order to allow the connecting member 400 to be placed therein. In this embodiment, the first recess 160 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 the bottom surface 162 of the first recess 160. In a top view, the shape of the first recess 160 is circular, and a substantially cylindrical space is formed inside it.

[0041] A second recess 260 is formed on the surface 210 of the base plate 200 that faces the dielectric substrate 100. The second recess 260 is formed on the surface 210 in the portion that overlaps with the first recess 160 when viewed from above. The second recess 260 is a portion of the surface 210 that has been recessed toward the surface 220 in order to allow the connecting member 400 to be placed therein. The metal portion of the base plate 200 is exposed throughout the inside of the second recess 260. The shape of the second recess 260 when viewed from above is circular, and a roughly 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 joint layer 300 between the first recess 160 and the second recess 260. The first recess 160 and the second recess 260 are connected through this opening, and the entire area forms a single space.

[0043] In Figure 3, the component labeled "310" is a component positioned to prevent uncured adhesive from seeping into the inside of the first recess 160 and the second recess 260. This component will also be referred to as the "blocking portion 310" below. In a top view, the blocking portion 310 is an annular component positioned to surround the first recess 160 from the outside all around. The inner diameter of the blocking portion 310 is the same as the inner diameter of the first recess 160, but it may be a different size. For example, cured silicone adhesive can be used as the blocking portion 310.

[0044] The connecting member 400 is a substantially cylindrical member formed from a fibrous metal material and is housed inside the first recess 160 and the second recess 260. In other words, a part of the connecting member 400 is housed in the first recess 160, and another part of the connecting member 400 is housed in the second recess 260.

[0045] The connecting member 400 is in contact with the RF electrode 140, which is exposed on the bottom surface 162 of the first recess 160. The connecting member 400 is also in contact with the metal portion of the base plate 200, which is exposed on the bottom surface 262 of the second recess 260. With the connecting member 400 positioned in this manner, the RF electrode 140 and the metal portion of the base plate 200 are electrically connected.

[0046] As shown in Figure 4, the connecting member 400 has a cylindrical main body 410 and a plurality of protrusions 420, and the entire structure is integrally formed from a fibrous metal material. In a top view, the shape of the connecting member 400 is circular. The diameter of this circle, i.e., the diameter of the main body 410, will hereafter be referred to as "diameter D1".

[0047] The protrusions 420 are substantially cylindrical projections formed on the main body portion 410 so as to extend further toward the dielectric substrate 100 from the surface facing the dielectric substrate 100. In this embodiment, a total of four protrusions 420 are formed, but the number of protrusions 420 may differ.

[0048] The connecting member 400, which is made of fibrous metal material, has enough permeability to allow fluids such as air and adhesive to enter its interior. In other words, the fibrous metal material is not sufficiently dense, 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 be easily deformed by external forces.

[0049] When no external force is being applied, the vertical dimension of the connecting member 400 (in the direction in which the protrusion 420 extends) is larger than the dimension in the same direction in the state shown in Figure 4. In other words, the connecting member 400 is compressed along the direction from the dielectric substrate 100 toward the base plate 200, and is housed inside the first recess 160 and the second recess 260, 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 by being 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 various parts 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 connecting member 400 may be different from that shown in Figure 4. For example, the entire connecting member 400 may be approximately cylindrical in shape and may not have a protruding portion 420.

[0052] Although there may be only one connecting member 400, in this embodiment multiple connecting members 400 are provided. Figure 2 shows the positions of each of the multiple connecting members 400 provided in the electrostatic chuck 10. In the actual configuration, the connecting members 400 cannot be seen from the surface 110 side, but in Figure 2, for the sake of explanation, each connecting member 400 is depicted as being visible from the surface 110 side through the dielectric substrate 100.

[0053] As shown in Figure 2, all of the multiple connecting members 400 are positioned in the region between the first seal ring 151 and the second seal ring 152 when viewed from above. The diameter D1 of the connecting member 400 when viewed from above is smaller than the distance D2 between the first seal ring 151 and the second seal ring 152.

[0054] Each of the multiple connecting members 400 is arranged in a ring shape along the second seal ring 152. The dashed-dotted line DL shown in Figure 2 is a hypothetical line extending parallel to the second seal ring 152. In a top view, the dashed-dotted line DL is circular, and its center coincides with the center of the dielectric substrate 100 and the base plate 200. In a top view, all the connecting members 400 are arranged such that the center of each connecting member 400 lies on the dashed-dotted line DL.

[0055] In this embodiment, each connecting member 400 is positioned so that, in a top view, it does not overlap with either the first seal ring 151 or the second seal ring 152. In other words, when considering any one connecting member 400, it does not overlap with the seal ring 150 at all in a top view. The same applies to all connecting members 400 provided on the electrostatic chuck 10.

[0056] Incidentally, since the connecting member 400 is made of metal, its thermal conductivity is relatively high. Therefore, 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 connecting member 400 due to the application of an AC voltage to the RF electrode 140. Depending on the amount of heat generated by the connecting member 400, the portion of the dielectric substrate 100 directly above the connecting member 400 may be locally overheated by the heat from the connecting member 400.

[0058] Thus, the connecting member 400 can act as either a heating source or a cooling source for the dielectric substrate 100. For this reason, if the connecting member 400 is positioned so as to overlap with 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. Since the seal ring 150 is in contact with the substrate W, if a localized temperature rise or fall occurs in the seal ring 150, the variation in the in-plane temperature distribution of the substrate W during processing may become too large.

[0059] Therefore, in the electrostatic chuck 10 according to this embodiment, the connecting member 400 is positioned so that its entirety does not overlap with the seal ring 150 at all. In this configuration, compared to a configuration in which the entire connecting member 400 overlaps with the seal ring 150 in a top view, local temperature rises or falls in the seal ring 150 can be suppressed. As a result, variations in the in-plane temperature distribution of the substrate W supported by the seal ring 150 can also be suppressed.

[0060] If Joule heating occurs in the connecting member 400, the connecting member 400 will expand due to thermal expansion while sandwiched between the dielectric substrate 100 and the base plate 200. At this time, the bottom surface 162 of the first recess 160 (see Figure 3) will receive force from the connecting member 400, which may cause a part of the dielectric substrate 100 to deform so that it becomes convex toward the substrate W. If, in a top view, the connecting member 400 and the seal ring 150 overlap each other, the above deformation will occur at the position of the seal ring 150, and 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 when viewed from above. Therefore, the deformation of the dielectric substrate 100 due to the thermal expansion of the connecting member 400 does not occur at the position of the seal ring 150, but occurs in a part of the bottom surface 116. Since the bottom surface 116 and the substrate W are spaced apart from each other, the deformation of the substrate W is suppressed to a negligible degree. Thus, in this embodiment, in addition to the effect of suppressing variations in the in-plane temperature distribution of the substrate W, the secondary effect of suppressing the deformation of the substrate W can also be achieved.

[0062] As mentioned above, in this embodiment, all connecting members 400 are positioned so as not to overlap with the seal ring 150 in any way when viewed from above. However, if local temperature changes of the seal ring 150 are not a problem, the above configuration may be replaced with a configuration in which some or all of the connecting members 400 overlap with the seal ring 150 when viewed from above.

[0063] As shown in Figure 2, all of the connecting members 400 in this embodiment are positioned so as not to overlap with either the seal ring 150 or the dot 113 when viewed from above. In other words, there are no parts (specifically the seal ring 150 and the dot 113) that come into solid contact with the substrate W directly above the connecting members 400, which can act as a heating or cooling source. Therefore, local temperature changes and local deformations of the substrate W directly above the connecting members 400 can be further suppressed.

[0064] In this embodiment, the multiple connecting members 400 are arranged in an annular pattern along the second seal ring 152 when viewed from above. Since the positional relationship between the connecting members 400 and the second seal ring 152 when viewed from above is approximately the same for all connecting members 400, the in-plane temperature distribution of the substrate W in the circumferential direction can be further made uniform. 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 an annular pattern and at equal intervals along the second seal ring 152 when viewed from above.

[0065] In this embodiment, all of the connecting members 400 provided on the electrostatic chuck 10 are arranged in a ring shape and at equal intervals when viewed from above. Alternatively, 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 and at equal intervals.

[0066] As previously mentioned, the group of dots 113A is positioned closest to the first seal ring 151 from the inside and is arranged in a ring shape along the first seal ring 151. Similarly, the group of dots 113B is positioned closest to the second seal ring 152 from the inside and is arranged 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 in a ring shape along the seal ring 150.

[0067] However, their radial positions are different from each other. "Radial position" refers to the distance from the center of the dielectric substrate 100 when viewed from above. More specifically, it refers to the distance from the center of the dielectric substrate 100 when viewed from above to the center of the connecting member 400, etc.

[0068] The radial position of each dot 113A is outside the radial position of the connecting member 400. Also, the radial position of each dot 113B is inside the radial position of the connecting member 400. In this embodiment, there are no dots 113 whose radial position is the same as that of the connecting member 400. With this configuration, it is possible to ensure a sufficiently large distance between the dots 113 and the connecting member 400 in a top view so that heat transfer to the substrate W via the dots 113 does not become a problem.

[0069] In this embodiment, all of the connecting members 400 provided on the electrostatic chuck 10 are positioned so that, when viewed from above, their centers are between the first seal ring 151 and the second seal ring 152. As a result, the multiple connecting members 400 are arranged in a line on the outer periphery of the dielectric substrate 100.

[0070] It is known that during processing of a substrate W in a semiconductor manufacturing apparatus, the alternating current flowing between a pair of counter electrodes, including the RF electrode 140, tends to flow unevenly towards the outer periphery of the dielectric substrate 100. Therefore, in this embodiment, the connecting member 400, which is part of the circuit, is placed in the outer periphery where the alternating current flows relatively easily. This makes the path of the alternating current approximately the shortest possible, allowing plasma to be efficiently drawn into the substrate W.

[0071] As shown in Figure 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 for supplying temperature-regulating gas 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 even 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 positioned such that their centers, when viewed from above, lie on the dashed line DL. In other words, the connecting member 400 and the gas holes 114 are arranged in a ring and in a single line when viewed from above. In this configuration, the distance between the connecting member 400 and the gas holes 114 is reduced, which increases the above-mentioned effect of homogenizing the in-plane temperature distribution of the substrate W during processing.

[0073] The second embodiment will now be described. The following will primarily focus on the differences from the first embodiment, while common points will be omitted as appropriate.

[0074] Figure 5 is a top view of the dielectric substrate 100 according to this embodiment. Note that the dots 113 and gas holes 114 located inside the second seal ring 152 are not shown in this figure. Also, the dots 113 located in the area between the first seal ring 151 and the second seal ring 152 are not shown.

[0075] In this embodiment, the portion of the first seal ring 151 designated with reference numeral "151A" is not arc-shaped but extends in a straight line. 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 with reference numeral "152A" is not arc-shaped but extends in a straight line. 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 Figure 5 is a hypothetical line extending parallel to the second seal ring 152. Of the dashed-dotted line DL, the portion adjacent to the non-circular portion 152A extends in a straight line parallel to the non-circular portion 152A. The other portions of the dashed-dotted line DL extend in an arc shape, similar to the dashed-dotted line DL in Figure 2, and their centers coincide with the centers of the dielectric substrate 100 and the base plate 200. In a top view, all the connecting members 400 are arranged such that the center of each connecting member 400 lies on the dashed-dotted line DL.

[0077] In this embodiment, as in the first embodiment, the connecting member 400 and the gas holes 114 are arranged alternately in the circumferential direction. Furthermore, the gas holes 114 arranged in this portion are all positioned such that the center of each hole, when viewed from above, lies on the dashed line DL. In other words, the connecting member 400 and the gas holes 114 are arranged in a ring and in a single line when viewed from above.

[0078] As described above, the configuration in which the connecting members 400 etc. are arranged in a "ring" shape includes not only the configuration in which the entirety of the connecting members 400 etc. are arranged in a ring shape, as in the first embodiment, but also the configuration in which a part of the connecting members 400 etc. are arranged in a linear shape, as in this embodiment. The same effects as those described in the first embodiment are achieved even with the above configuration.

[0079] A third embodiment will now be described. The following will primarily focus on the differences from the first embodiment, while common points will be omitted as appropriate.

[0080] Figure 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 connecting member 400 in the top view.

[0081] The dashed line DL1 shown in Figure 6 is a hypothetical line drawn at the same position as the dashed line DL shown in Figure 2 (first embodiment). The gas holes 114 formed in the portion between the first seal ring 151 and the second seal ring 152 are positioned such that the center of each gas hole 114 lies on the dashed line DL1 when viewed from above.

[0082] The dashed-dotted line DL2 shown in Figure 6 is a hypothetical line extending parallel to the second seal ring 152, similar to the dashed-dotted line DL1. In a top view, the dashed-dotted line DL2 is circular, and its center coincides with the center of the dielectric substrate 100 and the base plate 200. The dashed-dotted line DL2 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 such that the center of each connecting member 400 lies on the dashed-dotted line DL2 in a top view. In other words, the configuration of this embodiment can be described as a configuration in which each connecting member 400 is moved slightly inward from the configuration of the first embodiment shown in Figure 2.

[0083] In this embodiment, a portion of each connecting member 400 overlaps with the second seal ring 152 when viewed from above. However, the center of each connecting member 400 does not overlap with the second seal ring 152, but is located outside the second seal ring 152.

[0084] In other words, in this embodiment, when focusing on any one connecting member 400, only a portion of the connecting member 400 overlaps with the seal ring 150 in a top view. The portion of the connecting member 400 other than the center does not overlap with the seal ring 150 in a top view. Even in this configuration, variations in the in-plane temperature distribution of the substrate W during processing can be suppressed to some extent.

[0085] Thus, the connecting member 400 may be configured such that only a portion of it, including its center, is positioned so as not to overlap with the seal ring 150 when viewed from above. However, in order to sufficiently suppress variations in the in-plane temperature distribution of the substrate W, it is preferable, as in the first embodiment, for the entire connecting member 400, rather than just a portion of it, to be positioned so as not to overlap with the seal ring 150 when viewed from above.

[0086] In this embodiment, as in the first embodiment, the connecting member 400 and the gas holes 114 are arranged alternately in the circumferential direction.

[0087] Thus, the configuration in which the connecting member 400 and the gas holes 114 are arranged "alternatingly in the circumferential direction" includes not only the configuration in which the connecting member 400 and the gas holes 114 are arranged in a line along the same dashed line DL, but also the configuration in which the gas holes 114 are arranged in a line along the dashed line DL1 and the connecting member 400 is arranged in a line along the dashed line DL2. The same effects as those described in the first embodiment are achieved even with the above configuration.

[0088] A fourth embodiment will now be described. The following will primarily focus on the differences from the first embodiment, while commonalities will be omitted as appropriate.

[0089] Figure 7 shows the configuration of the electrostatic chuck 10 according to this embodiment, from the same viewpoint as in Figure 3. As shown in Figure 7, the first recess 160 in this embodiment is not formed to a depth that exposes the RF electrode 140. The bottom surface 162 of the first recess 160 is located on the surface 120 side of the RF electrode 140.

[0090] The bottom surface 162 of the first recess 160 is covered by 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 projection 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. Each via portion 142 is formed by filling the inside of a hole that extends along a direction perpendicular to the surface 120 with a conductive material such as tungsten. One end of each via portion 142 is connected to the metal plate 141, and the other end is connected to the RF electrode 140.

[0092] Thus, in this embodiment, the connecting member 400 and the RF electrode 140 are not directly connected, but are indirectly connected via the metal plate 141 and the via portion 142. This configuration also provides the same effects as those described in the first embodiment.

[0093] The embodiments have been described above with reference to specific examples. However, this disclosure is not limited to these specific examples. Modifications made to these specific examples by those skilled in the art are also included within the scope of this disclosure, as long as they retain the features of this disclosure. The elements, their arrangement, conditions, shapes, etc., of each of the aforementioned specific examples are not limited to those illustrated and can be modified as appropriate. The elements of each of the aforementioned specific examples can be combined in different ways as appropriate, as long as no technical inconsistencies arise. [Explanation of Symbols]

[0094] 10: Electrostatic Chuck 100: Dielectric substrate 110: Face 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: Circuit board

Claims

1. A dielectric substrate having a mounting surface on which an object to be adsorbed is placed, A seal ring comprising an annular projection formed on the dielectric substrate, the tip surface of which is part of the aforementioned mounting surface, An RF electrode provided inside the dielectric substrate, A base plate formed of metal and bonded to the dielectric substrate, The system includes a connecting member that electrically connects the RF electrode and the base plate, When viewed from a direction perpendicular to the mounting surface, The electrostatic chuck is characterized in that at least a portion of the connecting member is positioned so as not to overlap with the sealing ring.

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

3. When viewed from a direction perpendicular to the mounting surface, The electrostatic chuck according to claim 2, characterized in that the connecting member is positioned so that its entirety does not overlap with the seal ring.

4. The dielectric substrate further comprises a plurality of circular protrusions formed thereon, the tip surfaces of which are part of the aforementioned surface, When viewed from a direction perpendicular to the mounting surface, The electrostatic chuck according to claim 1, characterized in that at least a portion of the connecting member is positioned so as not to overlap with either the sealing ring or the dot.

5. When viewed from a direction perpendicular to the mounting surface, The electrostatic chuck according to claim 4, characterized in that a plurality of the connecting members are arranged in an annular pattern along the seal ring.

6. When viewed from a direction perpendicular to the mounting surface, The electrostatic chuck according to claim 5, characterized in that a plurality of the connecting members are arranged in an annular and equally spaced manner along the seal ring.

7. When viewed from a direction perpendicular to the mounting surface, Multiple of the aforementioned dots are arranged in a ring shape along the sealing ring, The radial position of each of the connecting members arranged in a ring is, The electrostatic chuck according to claim 5, characterized in that the radial position of each of the dots arranged in an annular shape is different from that of the dots.

8. The aforementioned seal ring is A first seal ring is positioned at the outermost edge of the mounting surface, The system includes a second seal ring positioned inside the first seal ring, without any other seal rings being placed between it and the first seal ring, When viewed from a direction perpendicular to the mounting surface, The electrostatic chuck according to claim 5, characterized in that each of the multiple connecting members is positioned so that its center is between the first seal ring and the second seal ring.

9. When viewed from a direction perpendicular to the mounting surface, The electrostatic chuck according to claim 8, characterized in that 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. When viewed from a direction perpendicular to the mounting surface, The electrostatic chuck according to claim 9, characterized in that the connecting member and the gas hole are arranged alternately in the circumferential direction.

11. When viewed from a direction perpendicular to the mounting surface, The electrostatic chuck according to claim 10, characterized in that the connecting member and the gas holes are arranged in an annular and linear fashion.

12. The aforementioned seal ring is A first seal ring is positioned at the outermost edge of the mounting surface, The system includes a second seal ring positioned inside the first seal ring, without any other seal rings being placed between it and the first seal ring, When viewed from a direction perpendicular to the mounting surface, The shape of the connecting member is circular. The diameter of the connecting member is The electrostatic chuck according to claim 1, characterized in that it is smaller than the distance between the first seal ring and the second seal ring.

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