Electrostatic chuck

Abstract

To provide an electrostatic chuck that can be easily manufactured although configured to electrically connect an internal electrode of a dielectric substrate and a base plate to each other by a conductive member.SOLUTION: An electrostatic chuck 10 comprises a dielectric substrate 100, an RF electrode 140 provided in the dielectric substrate 100, a base plate 200 made of metal and joined to the dielectric substrate 100, and a conductive member 400 making an electric connection between the RF electrode 140 and base plate 200. On a surface 120 of the dielectric substrate 100 on the side of the base plate 200, a first recessed part 160 is formed which houses a part of the conductive member 400. On a surface 210 of the base plate 200 on the side of the dielectric substrate 100, a second recessed part 260 is formed which houses a part of the conductive member 400. In top view, one of the first recessed part 160 and second recessed part 260 is larger than the other.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] For example, semiconductor manufacturing equipment such as etching equipment is provided with an electrostatic chuck as a device for attracting and holding a substrate, such as a silicon wafer, to be processed. The electrostatic chuck includes a dielectric substrate provided with an attracting electrode and a base plate that supports the dielectric substrate, which are joined together. When a voltage is applied to the attracting electrode, an electrostatic force is generated, and the substrate placed on the dielectric substrate is attracted and held.

[0003] As described in Patent Document 1 below, a dielectric substrate may have an RF electrode built in, which is one of a pair of opposing electrodes for generating plasma in a semiconductor manufacturing apparatus. In this case, the RF electrode and the base plate are electrically connected via a conductive member. This allows the potential of the RF electrode to be maintained at the potential of the base plate (e.g., ground potential) during substrate processing. [Prior art documents] [Patent documents]

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

[0005] To electrically connect the conductive 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 conductive member may be accommodated inside the recess. Similarly, to electrically connect the conductive member and the base plate, for example, a recess may be formed on the surface of the base plate facing the dielectric substrate, and the conductive member may be accommodated inside the recess. In this case, a portion of the conductive member is accommodated in the recess of the dielectric substrate, and another portion is accommodated in the recess of the base plate.

[0006] When manufacturing an electrostatic chuck having such a configuration, for example, with the surface of the base plate on which the recesses are formed facing upward, portions of the conductive members are inserted into the recesses so that the conductive members protrude vertically from the upper surface of the base plate. Thereafter, by bringing the surface of the dielectric substrate on which the recesses are formed (lower surface) closer to the surface of the base plate on which the recesses are formed (upper surface) and joining the two, the conductive members can be accommodated inside the respective recesses.

[0007] In this case, if the gap between the recess of the dielectric substrate and the conductive member is too small, alignment during the above-described bonding becomes difficult. Furthermore, if the gap between the recess of the base plate and the conductive member is too large, it becomes difficult to achieve a state in which the conductive member protrudes vertically from the upper surface of the base plate. Furthermore, since the position of the conductive member in this state is not fixed, alignment during bonding also becomes difficult. The same problem as above can occur when the electrostatic chuck is placed below and the base plate is moved toward it from above during bonding.

[0008] The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an electrostatic chuck that can be easily manufactured while having a configuration in which an internal electrode of a dielectric substrate and a base plate are electrically connected by a conductive member. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides an electrostatic chuck comprising: a dielectric substrate having a mounting surface on which an object to be attracted is placed; an internal electrode provided inside the dielectric substrate; a base plate made of metal and joined to the dielectric substrate; and a conductive member electrically connecting the internal electrode and the base plate. A first recess for accommodating a portion of the conductive member is formed on the surface of the dielectric substrate facing the base plate, and a second recess for accommodating a portion of the conductive member is formed on the surface of the base plate facing the dielectric substrate. When viewed from a direction perpendicular to the mounting surface, one of the first recess and the second recess is larger than the other.

[0010] When joining the dielectric substrate and the base plate, the member having the smaller of the first and second recesses is placed on the lower side, and after inserting a portion of the conductive member into the recess, the member having the larger of the first and second recesses is moved closer from above. Since the portion of the conductive member is inserted into the relatively small recess in the lower member, tipping or misalignment of the conductive member can be prevented. Since the relatively large recess in the upper member allows the portion of the conductive member to be easily accommodated in the recess when the upper member is moved closer to the lower member. In this way, by making the sizes of the first and second recesses different from each other when viewed from above, the electrostatic chuck having the above configuration can perform the joining operation during manufacturing more easily than in conventional electrostatic chucks. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an electrostatic chuck that can be easily manufactured while having a configuration in which an internal electrode of a dielectric substrate and a base plate are electrically connected by a conductive member. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view schematically showing the configuration of an electrostatic chuck according to a first embodiment. [Figure 2] 2 is a cross-sectional view showing in detail the configuration of a conductive member and its surrounding area of ​​the electrostatic chuck according to the first embodiment. FIG. [Figure 3] FIG. 2 is a perspective view showing a configuration of a conductive member. [Figure 4] 3A to 3C are diagrams for explaining a method for manufacturing an electrostatic chuck according to the first embodiment. [Figure 5] FIG. 10 is a cross-sectional view showing in detail the configuration of a conductive member and its surrounding area in an electrostatic chuck according to a second embodiment. [Figure 6] FIG. 10 is a cross-sectional view showing in detail the configuration of a conductive member and its surrounding area in an electrostatic chuck according to a third embodiment. [Figure 7] 10A to 10C are diagrams for explaining a method for manufacturing an electrostatic chuck according to a third embodiment. [Figure 8] FIG. 10 is a cross-sectional view showing in detail the configuration of a conductive member and its surrounding area in an electrostatic chuck according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

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

[0014] A first embodiment will be described. An electrostatic chuck 10 according to this embodiment is configured to electrostatically attract and hold a substrate W to be processed inside a semiconductor manufacturing apparatus (not shown), such as an etching apparatus. The object to be attracted, that is, the substrate W, is, for example, a silicon wafer. The electrostatic chuck 10 may also be used in apparatuses other than semiconductor manufacturing apparatuses.

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

[0016] The dielectric substrate 100 is a substantially disk-shaped member made of a sintered ceramic body. The dielectric substrate 100 contains, for example, high-purity aluminum oxide (Al2O3), but may also contain other materials. The purity, type, and additives of the ceramics in the dielectric substrate 100 can be appropriately set in consideration of the plasma resistance and other properties required of the dielectric substrate 100 in semiconductor manufacturing equipment.

[0017] 1 of the dielectric substrate 100 is a "mounting surface" on which the substrate W is placed. Also, a lower surface 120 of the dielectric substrate 100 in FIG. 1 is a "bonded surface" that is bonded to the base plate 200 via a bonding layer 300. The viewpoint when the electrostatic chuck 10 is viewed from the side of the surface 110 along a direction perpendicular to the surface 110 will hereinafter also be referred to as a "top view."

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

[0019] In addition to the above-described attraction electrode 130, an RF electrode 140 is also embedded inside the dielectric substrate 100. The RF electrode 140 is provided as one of a pair of opposing electrodes for generating plasma in the semiconductor manufacturing equipment. The other opposing electrode is provided at a position above the electrostatic chuck 10 in the semiconductor manufacturing equipment. When a high-frequency AC voltage is applied between these opposing electrodes, plasma is generated above the substrate W, and is used for processing the substrate W, such as film formation and etching. The RF electrode 140 corresponds to the "internal electrode" in this embodiment.

[0020] Like the chucking electrode 130, the RF electrode 140 is a thin, flat layer made of a metal material such as tungsten. In addition to tungsten, molybdenum, platinum, palladium, etc. may also be used as the material of the RF electrode 140. The RF electrode 140 is embedded at a position closer to the surface 120 than the chucking electrode 130. Like the chucking electrode 130, the RF electrode 140 is disposed so as to be parallel to the surface 110. The RF electrode 140 is a single electrode that is substantially circular in top view. The center of the RF electrode 140 in top view coincides with the center of the dielectric substrate 100.

[0021] The electrostatic chuck 10 is provided with a conductive member 400. The conductive member 400 is a member for electrically connecting the RF electrode 140 and a base plate 200, which will be described later. The conductive 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 conductive member 400 is schematically depicted as a simple straight line. The specific shape of the conductive member 400 will be described later.

[0022] As shown in Fig. 1, a space SP is formed between the dielectric substrate 100 and the substrate W. When a process such as etching is performed in the semiconductor manufacturing equipment, helium gas for temperature adjustment is supplied to the space SP from the outside through a gas hole (not shown). 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 gas other than helium.

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

[0024] The seal ring 111 is a wall that partitions the space SP at the outermost position. The seal ring 111 is an annular protrusion formed on the surface 110. The tip (the upper end in FIG. 1) of the seal ring 111 is part of the surface 110 and abuts against the substrate W. The tip of the seal ring 111 can be said to be the outermost part of the surface 110, which is the mounting surface.

[0025] It should be noted that a plurality of seal rings 111 may be provided to divide the space SP. With such a configuration, the pressure of the helium gas in each space SP can be adjusted individually, and the surface temperature distribution of the substrate W during processing can be made more uniform.

[0026] 1, the portion marked with 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 111, together with the dots 112 described below, is formed by digging down a portion of the surface 110 to the position of the bottom surface 116.

[0027] The dots 112 are circular protrusions that protrude from the bottom surface 116. A plurality of dots 112 are provided, and are distributed approximately evenly on the mounting surface of the dielectric substrate 100. The tip of each dot 112 forms part of the surface 110 and comes into contact with the substrate W. By providing a plurality of such dots 112, bending of the substrate W is suppressed.

[0028] The base plate 200 is a substantially disk-shaped member that supports the dielectric substrate 100. The base plate 200 is formed of a metal material such as aluminum. The base plate 200 is bonded to the surface 120 of the dielectric substrate 100 via a bonding layer 300. The surface 210 of the base plate 200, which is on the upper side in FIG. 1, is the "bonded surface" that is bonded to the dielectric substrate 100.

[0029] The bonding layer 300 is a layer provided between the dielectric substrate 100 and the base plate 200, and bonds them together. The bonding layer 300 is formed by curing an adhesive made of an insulating material. In this embodiment, a silicone adhesive is used as the adhesive. However, the bonding layer 300 may be formed by curing another type of adhesive. In either case, it is preferable to use a material with as high a thermal conductivity as possible as the material for the bonding layer 300 so as to reduce the thermal resistance between the dielectric substrate 100 and the base plate 200.

[0030] An insulating film may be formed on the surface of the base plate 200. For example, an alumina film formed by thermal spraying can be used as the insulating film. By covering the surface of the base plate 200 with an insulating film, the dielectric strength of the base plate 200 can be increased.

[0031] A coolant flow path 250 for passing a coolant is formed inside the base plate 200. When a process such as etching is performed in the semiconductor manufacturing equipment, a coolant is supplied to the coolant flow path 250 from the outside, thereby cooling the base plate 200. Heat generated in the substrate W during the process is transferred to the coolant via the helium gas in the space SP, the dielectric substrate 100, and the base plate 200, and is discharged to the outside together with the coolant. The coolant is supplied to and discharged from the coolant flow path 250 through an opening (not shown) formed in a surface 220 of the base plate 200 opposite to the surface 210.

[0032] The specific configuration of the conductive member 400 and its surrounding area will be described with reference to FIG. 2. As shown in the figure, 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 conductive member 400 to be disposed therein. The first recess 160 of this embodiment is formed to a depth position that exposes the RF electrode 140. Therefore, the RF electrode 140, which is an internal electrode, is exposed at a bottom surface 162 of the first recess 160. The first recess 160 has a circular shape when viewed from above, and a substantially cylindrical space is formed inside the circular shape.

[0033] A second recess 260 is formed in the surface 210 of the base plate 200 facing the dielectric substrate 100. The second recess 260 is formed in a portion of the surface 210 that overlaps with the first recess 160 in a top view. The second recess 260 is a portion of the surface 210 that is recessed toward the surface 220 to allow for the placement of the conductive 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.

[0034] 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.

[0035] The member marked with the reference numeral "310" in FIG. 2 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 different from the inner diameter of the first recess 160. For example, a cured silicone adhesive is used as the blocking portion 310.

[0036] The conductive 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. That is, a portion of the conductive member 400 is housed in the first recess 160, and another portion of the conductive member 400 is housed in the second recess 260. In a top view, the diameter of the portion of the conductive member 400 housed in the first recess 160 is equal to the diameter of the portion of the conductive member 400 housed in the second recess 260.

[0037] The conductive member 400 abuts against the RF electrode 140 exposed at the bottom surface 162 of the first recess 160. The conductive 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 conductive member 400 arranged in this manner electrically connects the RF electrode 140 and the metal portion of the base plate 200.

[0038] 3, the conductive member 400 has a substantially cylindrical main body 410 and a plurality of protruding portions 420, the entire body being integrally formed from a fibrous metal member. The protruding portions 420 are substantially 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 protruding portions 420 are formed, but the number of protruding portions 420 may be different.

[0039] Conductive member 400, which is made of a fibrous metal material, has sufficient breathability to allow fluids such as air and adhesive to penetrate inside. In other words, the fibrous metal material is not dense enough, and there are gaps between the fibers. With this configuration, each part of conductive member 400, including protrusion 420, is an elastic body that can easily deform when subjected to an external force.

[0040] When no external force is applied, the dimension of the conductive 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. 2. In other words, the conductive member 400 is housed inside the first recess 160 and the second recess 260 in a state in which it is compressed in the direction from the dielectric substrate 100 toward the base plate 200, and is sandwiched between the RF electrode 140 and the base plate 200. The tip of each protrusion 420 is elastically deformed so as to be crushed when pressed against the bottom surface 162 of the first recess 160 (i.e., the RF electrode 140).

[0041] The conductive member 400 is pressed against the RF electrode 140 and the base plate 200 by its own restoring force. Therefore, even if thermal expansion or contraction occurs in each part of the electrostatic chuck 10 during processing of the substrate W, etc., the electrical connection between the RF electrode 140 and the base plate 200 is always maintained.

[0042] The number of conductive members 400 may be one or more. For example, a plurality of spaces each formed by the first recess 160 and the second recess 260 may be formed so as to be lined up in the circumferential direction, and each space may house one conductive member 400.

[0043] A shape different from that of this embodiment may be adopted as the shape of the conductive member 400. For example, the entire conductive member 400 may be formed in a substantially cylindrical shape, and may not have the protruding portion 420.

[0044] Among the methods for manufacturing the electrostatic chuck 10, a method for joining the dielectric substrate 100 and the base plate 200 will be described with reference to Fig. 4. In Fig. 4, the respective configurations of the dielectric substrate 100, the base plate 200, and the conductive member 400 are depicted in a simplified schematic manner.

[0045] First, the base plate 200 is placed on a workbench (not shown) with the surface 210 facing upward. A second recess 260 is formed in the surface 210 in advance. An adhesive that will become the bonding layer 300 after hardening is applied in advance to substantially the entire surface 210. The adhesive is not shown in FIG. 4. The adhesive may be applied in advance to the surface 120 of the dielectric substrate 100.

[0046] Next, the conductive members 400 are inserted into the respective second recesses 260. As shown in FIG. 4, each conductive member 400 is in a state where a portion thereof protrudes perpendicularly from the surface 210 of the base plate 200.

[0047] Thereafter, the dielectric substrate 100 is brought closer to the surface 210 from above, with the surface 120 facing downward. First recesses 160 are formed in advance on the surface 120. The dielectric substrate 100 and the base plate 200 are aligned with each other so that each first recess 160 is directly above each second recess 260. The dielectric substrate 100 is joined to the base plate 200 while being moved along the arrows in FIG. 4. When the movement is complete, each conductive member 400 is housed inside the first recess 160 and the second recess 260. The entire assembly is then heated to harden the adhesive, thereby completing the electrostatic chuck 10 shown in FIG. 1.

[0048] If the inner diameter of the first recess 160 formed in the dielectric substrate 100 were smaller than the inner diameter of this embodiment, for example, approximately the same as the inner diameter of the second recess 260, it would be difficult to align the dielectric substrate 100 when moving it closer to the base plate 200 below. That is, it would be difficult to fit each conductive member 400 inside the first recess 160. Therefore, in this embodiment, the inner diameter of the first recess 160 is made larger than the inner diameter of the second recess 260. This makes it possible to easily fit each conductive member 400 inside the first recess 160 while moving the dielectric substrate 100 downward.

[0049] Furthermore, if the inner diameter of the second recess 260 formed in the base plate 200 were larger than that of the present embodiment, the gap between the inner circumferential surface 261 of the second recess 260 and the conductive member 400 would be larger, making it difficult to achieve a state in which the conductive member 400 protrudes perpendicularly from the surface 210 of the base plate 200. Furthermore, since the position of the conductive member 400 in this state would be inaccurate, it would also be difficult to align the dielectric substrate 100 when moving it toward the lower base plate 200. Therefore, in this embodiment, the inner diameter of the second recess 260 is smaller than the inner diameter of the first recess 160 and is approximately the same size as the outer diameter of the conductive member 400. Since a portion of the conductive member 400 is inserted into the relatively small second recess 260, tipping or misalignment of the conductive member 400 is prevented. As a result, the above-described bonding operation during the manufacture of the electrostatic chuck 10 can be easily performed.

[0050] Incidentally, since the conductive member 400 is a metal member, its thermal conductivity is relatively high. Therefore, during processing of the substrate W, a portion of the dielectric substrate 100 near the conductive member 400 may be excessively cooled by the base plate 200 via the conductive member 400. Furthermore, if the amount of heat generated by the conductive member 400 increases as a result of energization of the RF electrode 140, a portion of the dielectric substrate 100 near the conductive member 400 may be excessively heated by the conductive member 400. Such localized cooling or heating by the conductive member 400 is thought to be particularly likely to occur when the inner circumferential surface 161 of the first recess 160 is in wide contact with the side surface of the conductive member 400, resulting in increased heat transfer between them.

[0051] If the conductive member 400 locally cools or heats the dielectric substrate 100 excessively, there is a possibility that the in-plane temperature distribution of the substrate W during processing will vary greatly. Therefore, in the electrostatic chuck 10 according to this embodiment, the shapes of the first recess 160 and the second recess 260 are devised to solve the problem of the in-plane temperature distribution as well.

[0052] In this embodiment, the diameter of the inner circumferential surface 261 of the second recess 260 is approximately equal to the diameter of the main body 410 of the conductive member 400. On the other hand, the diameter of the inner circumferential surface 161 of the first recess 160 is larger than the diameter of the inner circumferential surface 261 of the second recess 260. Therefore, in a top view, the first recess 160 is larger than the second recess 260. The inner circumferential surface 161 of the first recess 160 is located outside the inner circumferential surface 261 of the second recess 260 over the entire circumference.

[0053] With this configuration, it is possible to ensure a constant distance from the inner circumferential surface 161 of the first recess 160 to the side surface of the conductive member 400 all around. A relatively large gap is formed between the inner circumferential surface 161 of the first recess 160 and the side surface of the conductive member 400, reducing heat transfer between them. As a result, local temperature increases and decreases are less likely to occur in the vicinity of the conductive member 400 on the dielectric substrate 100, thereby suppressing variations in the in-plane temperature distribution of the substrate W during processing.

[0054] When the workability during joining as described above is not an issue, the diameter of the inner circumferential surface 261 of the second recess 260 may be larger than the diameter of the main body 410 of the conductive member 400. In this case as well, it is sufficient to make the diameter of the inner circumferential surface 161 of the first recess 160 even larger than the diameter of the inner circumferential surface 261 of the second recess 260.

[0055] In a top view, the inner circumferential surface 161 of the first recess 160 and the inner circumferential surface 261 of the second recess 260 may be partially close to each other or partially overlap each other. However, in order to sufficiently suppress heat transfer between the dielectric substrate 100 and the conductive member 400, it is preferable that the inner circumferential surface 161 of the first recess 160 and the inner circumferential surface 261 of the second recess 260 are concentric in a top view, as in this embodiment.

[0056] The diameter of the portion of the conductive member 400 housed in the first recess 160 and the diameter of the portion of the conductive member 400 housed in the second recess 260 may be different from each other. In this case, too, it is preferable to form each of the first recess 160 and the second recess 260 so that the distance from the inner circumferential surface 161 of the first recess 160 to the side surface of the conductive member 400 is greater than the distance from the inner circumferential surface 261 of the second recess 260 to the side surface of the conductive member 400 over the entire circumference.

[0057] The second embodiment will be described below. Differences from the first embodiment will be mainly described below, and descriptions of commonalities with the first embodiment will be omitted as appropriate.

[0058] Fig. 5 illustrates the configuration of the electrostatic chuck 10 according to this embodiment from the same perspective as Fig. 2. As shown in Fig. 5, 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.

[0059] The bottom surface 162 of the first recess 160 is covered with a metal plate 141. The metal plate 141 is a plate-shaped member made of, for example, molybdenum, and is in close contact with almost the entire bottom surface 162. In this embodiment, the tip of the protrusion 420 is pressed against the metal plate 141.

[0060] 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.

[0061] As described above, in this embodiment, the conductive member 400 and the RF electrode 140 are not directly connected to each other, but are indirectly connected to each other through the metal plate 141 and the via portion 142. Even in this embodiment, the same effects as those described in the first embodiment can be achieved.

[0062] A third embodiment will be described below. The following mainly describes the differences from the first embodiment, and the description of the commonalities with the first embodiment will be omitted as appropriate.

[0063] 6 illustrates the configuration of the electrostatic chuck 10 according to this embodiment from the same perspective as FIG. 2. As shown in FIG. 6, in this embodiment, the diameter of the inner circumferential surface 161 of the first recess 160 is approximately equal to the diameter of the main body 410 of the conductive member 400. On the other hand, the diameter of the inner circumferential surface 261 of the second recess 260 is larger than the diameter of the inner circumferential surface 161 of the first recess 160. Therefore, in a top view, the second recess 260 is larger than the first recess 160. The inner circumferential surface 261 of the second recess 260 is located outside the inner circumferential surface 161 of the first recess 160 over the entire circumference.

[0064] The shape of the conductive member 400 is the same as in the first embodiment. Therefore, in a top view, the diameter of the portion of the conductive member 400 housed in the first recess 160 is equal to the diameter of the portion of the conductive member 400 housed in the second recess 260.

[0065] Among the methods for manufacturing the electrostatic chuck 10 according to this embodiment, a method for joining the dielectric substrate 100 and the base plate 200 will be described with reference to Fig. 7. In Fig. 7, the respective configurations of the dielectric substrate 100, the base plate 200, and the conductive member 400 are depicted in a simplified schematic manner.

[0066] First, the dielectric substrate 100 is placed on a work table (not shown) with the surface 120 facing upward. A first recess 160 is formed in advance in the surface 120. An adhesive that will become the bonding layer 300 after hardening is applied in advance to substantially the entire surface 120. The adhesive is not shown in FIG. 7. The adhesive may be applied in advance to the surface 210 of the base plate 200.

[0067] Next, the conductive members 400 are inserted into the respective first recesses 160. As shown in FIG. 7, each conductive member 400 is in a state where a portion thereof protrudes perpendicularly from the surface 120 of the dielectric substrate 100.

[0068] Thereafter, the base plate 200 is moved from above toward the surface 120 with the surface 210 facing downward. Second recesses 260 are formed in advance in the surface 210. The dielectric substrate 100 and the base plate 200 are aligned with each other so that the second recesses 260 are directly above the first recesses 160. The base plate 200 is joined to the dielectric substrate 100 while being moved along the arrows in FIG. 7. When the movement is complete, the conductive members 400 are housed inside the first recesses 160 and the second recesses 260. The entire assembly is then heated to harden the adhesive, thereby completing the electrostatic chuck 10 according to this embodiment.

[0069] If the inner diameter of the second recess 260 formed in the base plate 200 were smaller than the inner diameter of this embodiment, for example, approximately the same as the inner diameter of the first recess 160, it would be difficult to align the base plate 200 when moving it closer to the dielectric substrate 100 below. That is, it would be difficult to fit each conductive member 400 inside the second recess 260. Therefore, in this embodiment, the inner diameter of the second recess 260 is made larger than the inner diameter of the first recess 160. This makes it possible to easily fit each conductive member 400 inside the second recess 260 while moving the dielectric substrate 100 downward.

[0070] Furthermore, if the inner diameter of the first recess 160 formed in the dielectric substrate 100 were larger than that of the present embodiment, the gap between the inner circumferential surface 161 of the first recess 160 and the conductive member 400 would be larger, making it difficult to achieve a state in which the conductive member 400 protrudes perpendicularly from the surface 120 of the dielectric substrate 100. Furthermore, since the position of the conductive member 400 in this state would be inaccurate, it would also be difficult to align the base plate 200 when moving it toward the dielectric substrate 100 below. Therefore, in this embodiment, the inner diameter of the first recess 160 is smaller than the inner diameter of the second recess 260 and is approximately the same size as the outer diameter of the conductive member 400. Because a portion of the conductive member 400 is inserted into the relatively small first recess 160, tipping or misalignment of the conductive member 400 is prevented. As a result, the above-described bonding operation during the manufacture of the electrostatic chuck 10 can be easily performed.

[0071] In this way, even in a configuration in which the size relationship between the first recess 160 and the second recess 260 in top view is reversed from that of the first embodiment, it is possible to achieve the same effects as those described in the first embodiment. Which of the first recess 160 and the second recess 260 should be made larger can be determined depending on which member is to be placed on the lower side when joining the dielectric substrate 100 and the base plate 200.

[0072] A fourth embodiment will be described below. The following mainly describes the differences from the third embodiment, and the description of the commonalities with the third embodiment will be omitted as appropriate.

[0073] Fig. 8 illustrates the configuration of the electrostatic chuck 10 according to this embodiment from the same perspective as Fig. 6. As shown in Fig. 8, 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.

[0074] The bottom surface 162 of the first recess 160 is covered with a metal plate 141. The metal plate 141 is a plate-shaped member made of, for example, molybdenum, and is in close contact with almost the entire bottom surface 162. In this embodiment, the tip of the protrusion 420 is pressed against the metal plate 141.

[0075] 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.

[0076] As described above, in this embodiment, the conductive member 400 and the RF electrode 140 are not directly connected to each other, but are indirectly connected to each other through the metal plate 141 and the via portion 142. Even in this embodiment, the same effects as those described in the third embodiment can be achieved.

[0077] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise. [Explanation of symbols]

[0078] 10: Electrostatic chuck 100: Dielectric substrate 110,120: face 140:RF electrode 160: First recess 400: Conductive material 200: Base plate 210: Face 260: Second recess W: Substrate

Claims

1. a dielectric substrate having a mounting surface on which an object to be attracted is placed; an internal electrode provided inside the dielectric substrate; a base plate made of metal and bonded to the dielectric substrate; a conductive member electrically connecting the internal electrode and the base plate, a first recess that accommodates a portion of the conductive member is formed in a surface of the dielectric substrate that faces the base plate; a second recess that accommodates a portion of the conductive member is formed in a surface of the base plate that faces the dielectric substrate; When viewed from a direction perpendicular to the mounting surface, the first recess is larger than the second recess, An electrostatic chuck, wherein the inner diameter of the second recess is sized to prevent the conductive member inserted into the second recess from tipping over.

2. When viewed from a direction perpendicular to the placement surface, 2. The electrostatic chuck according to claim 1, wherein an inner peripheral surface of the first recess is located outside an inner peripheral surface of the second recess over the entire periphery.

3. When viewed from a direction perpendicular to the placement surface, 3. The electrostatic chuck according to claim 2, wherein a diameter of the portion of the conductive member housed in the first recess is equal to a diameter of a portion of the conductive member housed in the second recess.

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