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 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] 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 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

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In order to electrically connect between the conductive member and the RF electrode, for example, a recess may be formed in the surface of the dielectric substrate on the base plate side, the RF electrode may be exposed on the bottom surface thereof, and then the conductive member may be accommodated inside the recess. Similarly, in order to electrically connect between the conductive member and the base plate, for example, a recess may be formed in the surface of the base plate on the dielectric substrate side, and the conductive member may be accommodated inside the recess. In this case, a part of the conductive member will be accommodated in the recess of the dielectric substrate and the other part will be 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 in which the recess is formed facing upward, a part of the conductive member is inserted into each recess, and the conductive member is made to protrude vertically from the upper surface of the base plate. Then, while bringing the surface of the dielectric substrate in which the recess is formed (lower surface) closer to the surface of the base plate in which the recess is formed (upper surface), if the two are joined, the conductive member can be accommodated inside each recess.

[0007] At this time, if the gap between the recess of the dielectric substrate and the conductive member is too small, it becomes difficult to perform alignment when performing the above-described joining. Also, if the gap between the recess of the base plate and the conductive member is too large, it becomes difficult to make the conductive member protrude vertically from the upper surface of the base plate in the first place. Further, since the position of the conductive member in this state is not determined, alignment when performing the joining also becomes difficult. The same problem can occur even when the electrostatic chuck is arranged on the lower side and the base plate is brought closer from the upper side when performing the joining.

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

Means for Solving the Problems

[0009] In order to solve the above problems, the electrostatic chuck according to the present invention includes a dielectric substrate having a placement surface on which an object to be adsorbed is placed, an internal electrode provided inside the dielectric substrate, a base plate formed of metal and joined to the dielectric substrate, and a conductive member that electrically connects the internal electrode and the base plate. On the surface of the dielectric substrate on the base plate side, a first recess for accommodating a part of the conductive member is formed, and on the surface of the base plate on the dielectric substrate side, a second recess for accommodating a part of the conductive member is formed. When viewed from a direction perpendicular to the placement 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 in which the smaller of the first recess and the second recess is formed is arranged on the lower side, and after inserting a part of the conductive member into the recess, the member in which the larger of the first recess and the second recess is formed is brought closer from the upper side. In the member on the lower side, since a part of the conductive member is inserted into the relatively small recess, it is possible to prevent the conductive member from falling or being displaced. Since a relatively large recess is formed in the member on the upper side, when bringing the member closer to the member on the lower side, a part of the conductive member can be easily accommodated in the recess. Thus, in the electrostatic chuck having the above configuration, by making the sizes of the first recess and the second recess in a top view different from each other, the joining operation during manufacturing can be performed more easily than before.

Effect 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 the internal electrode of the dielectric substrate and the base plate are electrically connected by a conductive member.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

MODE FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, this embodiment will be described with reference to the accompanying drawings. For ease of understanding of the description, the same reference numerals are given to the same components in each drawing as much as possible, and duplicate descriptions are omitted.

[0014] 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.

[0015] FIG. 1 schematically shows the configuration of the electrostatic chuck 10 in a state where the substrate W is adsorbed and held as a cross-sectional view. 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 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, etc. required for the dielectric substrate 100 in a semiconductor manufacturing apparatus.

[0017] Among the dielectric substrate 100, the upper surface 110 in FIG. 1 serves as the "placement surface" on which the substrate W is placed. Also, among the dielectric substrate 100, the lower surface 120 in FIG. 1 serves as the "surface to be joined" that is joined to the base plate 200 via the joining layer 300. The viewpoint when looking at the surface 110 side from the electrostatic chuck 10 along the direction perpendicular to the surface 110 will also be hereinafter referred to as the "top view".

[0018] An adsorption electrode 130 is embedded inside the dielectric substrate 100. The adsorption electrode 130 is a thin flat plate-shaped 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 via a power supply path (not shown), an electrostatic force is generated between the surface 110 and the substrate W, and thereby the substrate W is adsorbed and held. As the configuration of the above power supply path, various known configurations can be adopted. The adsorption electrode 130 may be provided only one as a so-called "single-pole" electrode as in this embodiment, or may be provided two as a so-called "bipolar" electrode.

[0019] Inside the dielectric substrate 100, in addition to the adsorption electrode 130 described above, 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. The RF electrode 140 corresponds to the "internal electrode" in the present embodiment.

[0020] 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 substantially circular electrode in a top view. The center of the RF electrode 140 in a top view coincides with the center of the dielectric substrate 100.

[0021] A conductive member 400 is provided on the electrostatic chuck 10. The conductive member 400 is a member for electrically connecting between the RF electrode 140 and a base plate 200 described later. Due to the conductive member 400, the potential of the RF electrode 140 during the processing of the substrate W becomes the same as the potential of the base plate 200. In FIG. 1, the conductive member 400 is schematically drawn 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 a semiconductor manufacturing apparatus, helium gas for temperature adjustment is supplied from the outside to the space SP through a gas hole (not shown). By interposing helium gas between the dielectric substrate 100 and the substrate W, the thermal resistance between the two is adjusted, and thereby the temperature of the substrate W is maintained at an appropriate temperature. Note that the gas for temperature adjustment supplied to the space SP may be a gas of a type different from helium.

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

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

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

[0026] The portion denoted by reference numeral “116” in FIG. 1 is the bottom surface of the space SP. Hereinafter, this portion will also be referred to as “bottom surface 116”. The seal ring 111, together with the dots 112 described below, is formed as a result of digging down a part of the surface 110 to the position of the bottom surface 116.

[0027] Dot 112 is a circular protrusion protruding from the bottom surface 116. A plurality of dots 112 are provided and are arranged substantially evenly and dispersedly on the placement surface of the dielectric substrate 100. The tip of each dot 112 forms a part of the surface 110 and abuts against the substrate W. By providing a plurality of such dots 112, the deflection 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, for example. The base plate 200 is joined to the surface 120 of the dielectric substrate 100 via the joining layer 300. Among the base plate 200, the upper surface 210 in FIG. 1 is the "surface to be joined" joined to the dielectric substrate 100.

[0029] The joining layer 300 is a layer provided between the dielectric substrate 100 and the base plate 200 and joins the two. The joining layer 300 is obtained by curing an adhesive made of an insulating material. In the present embodiment, a silicone adhesive is used as the adhesive. However, the joining layer 300 may be obtained by curing another type of adhesive. In any case, as the material of the joining layer 300, it is preferable to use a material having as high a thermal conductivity as possible so that the thermal resistance between the dielectric substrate 100 and the base plate 200 is reduced.

[0030] 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 spraying can be used. By covering the surface of the base plate 200 with the insulating film, the dielectric breakdown voltage of the base plate 200 can be increased.

[0031] Inside the base plate 200, a refrigerant flow path 250 for passing refrigerant is formed. When a process such as etching is performed in the semiconductor manufacturing apparatus, refrigerant is supplied from the outside to the refrigerant flow path 250, and thereby the base plate 200 is cooled. The heat generated in the substrate W during the process is transmitted to the refrigerant through 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 the refrigerant to and from the refrigerant flow path 250 are performed through an opening (not shown) formed in the surface 220 of the base plate 200 on the side opposite to the surface 210.

[0032] The specific configuration of the conductive member 400 and its vicinity 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 on the side of the base plate 200. The first recess 160 is a portion where a part of the surface 120 is recessed backward toward the surface 110 side in order to enable the arrangement of the conductive member 400. The first recess 160 of the present embodiment is formed to a depth position that exposes the RF electrode 140. Therefore, at the bottom surface 162 of the first recess 160, the RF electrode 140, which is an internal electrode, is exposed. The shape of the first recess 160 in a top view is circular, and a substantially cylindrical space is formed inside thereof.

[0033] A second recess 260 is formed in the surface 210 of the base plate 200 on the side of 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 where a part of the surface 210 is recessed backward toward the surface 220 side in order to enable the arrangement of the conductive member 400. Inside the second recess 260, the metal portion of the base plate 200 is entirely exposed. The shape of the second recess 260 in a top view is circular, and a substantially cylindrical space is formed inside thereof. The central axis of the second recess 260 coincides with the central axis of the first recess 160. However, the diameter of the inner peripheral surface 261 of the second recess 260 is smaller than the diameter of the inner peripheral surface 161 of the first recess 160.

[0034] In the bonding layer 300, a circular opening is formed in the portion between the first recess 160 and the second recess 260. The space between the first recess 160 and the second recess 260 is connected through the opening, and the whole of these constitutes one space.

[0035] In FIG. 2, the member marked with the reference numeral "310" is a member arranged to prevent uncured adhesive from entering inside the first recess 160 and the second recess 260. This member is hereinafter also referred to as the "blocking portion 310". The blocking portion 310 is an annular member arranged to surround the first recess 160 entirely in a top view from the outside. The inner diameter of the blocking portion 310 may be the same as the inner diameter of the first recess 160, or may have a size different from the inner diameter of the first recess 160. As the blocking portion 310, for example, a cured silicone adhesive is used.

[0036] The conductive member 400 is a substantially cylindrical member formed of a fibrous metal member and is housed inside the first recess 160 and the second recess 260. That is, a part of the conductive member 400 is housed in the first recess 160, and the other part 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 is in contact with the RF electrode 140 exposed at the bottom surface 162 of the first recess 160. The conductive member 400 is also in contact with the metal portion of the base plate 200 exposed at the bottom surface 262 of the second recess 260. By the conductive member 400 arranged in this way, the RF electrode 140 and the metal portion of the base plate 200 are electrically connected.

[0038] As shown in FIG. 3, the conductive member 400 has a substantially cylindrical main body portion 410 and a plurality of protruding portions 420, and the whole is integrally formed by a fibrous metal member. The protruding portion 420 is a substantially cylindrical protrusion formed so as to extend further toward the dielectric substrate 100 from the surface of the main body portion 410 on the dielectric substrate 100 side. In the present embodiment, a total of four protruding portions 420 are formed, but the number of protruding portions 420 may be different from this.

[0039] The conductive member 400 made of a fibrous metal member has air permeability such that fluids such as air and an adhesive can enter therein. That is, the fibrous metal member is not sufficiently dense, and there are gaps between the fibers. By adopting such a configuration, the conductive member 400 is an elastic body in which each part including the protruding portion 420 can be easily deformed by an external force.

[0040] When no external force is applied, the dimension of the conductive member 400 in the vertical direction (the direction in which the protruding portion 420 extends) is larger than the dimension in the same direction in the state of FIG. 2. That is, the conductive member 400 is accommodated inside the first recess 160 and the second recess 260 in a compressed state along 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 protruding portion 420 is elastically deformed so as to be crushed by being pressed against the bottom surface 162 (that is, the RF electrode 140) of the first recess 160.

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

[0042] The number of the conductive members 400 may be one or plural. For example, a mode may be adopted in which a plurality of spaces each composed of the first concave portion 160 and the second concave portion 260 are formed side by side along the circumferential direction, and one conductive member 400 is accommodated in each space.

[0043] As the shape of the conductive member 400, a shape different from that of the present embodiment may be adopted. For example, the whole of the conductive member 400 may be substantially cylindrical and may not have the protruding portion 420.

[0044] Among the manufacturing methods of the electrostatic chuck 10, a method of joining between the dielectric substrate 100 and the base plate 200 will be described with reference to FIG. 4. In the figure, the configurations of the dielectric substrate 100, the base plate 200, and the conductive member 400 are schematically drawn in a simplified manner.

[0045] First, the base plate 200 is placed on a workbench (not shown) with the surface 210 facing upward. The second concave portion 260 is formed in advance on the surface 210. Also, an adhesive that will become the bonding layer 300 after curing is applied in advance over substantially the entire surface 210. In FIG. 4, the illustration of the adhesive is omitted. The adhesive may be applied in advance toward the surface 120 of the dielectric substrate 100.

[0046] Subsequently, the conductive members 400 are inserted into the respective second concave portions 260. As shown in FIG. 4, a part of each conductive member 400 protrudes vertically from the surface 210 of the base plate 200.

[0047] Thereafter, while the dielectric substrate 100 is moved along the arrow in FIG. 4, the dielectric substrate 100 is brought close to the base plate 200 from above with the surface 120 facing downward. A first recess 160 is formed in the surface 120 in advance. Also, the dielectric substrate 100 and the base plate 200 are aligned with each other such that each first recess 160 is directly above each second recess 260. While moving the dielectric substrate 100 along the arrow in FIG. 4, the dielectric substrate 100 is joined to the base plate 200. When the movement is completed, each conductive member 400 is in a state of being housed inside the first recess 160 and the second recess 260. Thereafter, the whole is heated to cure the above-described adhesive, whereby the electrostatic chuck 10 shown in FIG. 1 is completed.

[0048] If the inner diameter of the first recess 160 formed in the dielectric substrate 100 is smaller than the inner diameter of the present embodiment, for example, if it is approximately the same as the inner diameter of the second recess 260, it becomes difficult to align the dielectric substrate 100 when bringing it closer to the lower base plate 200. That is, it becomes difficult to insert each conductive member 400 inside the first recess 160. Therefore, in the present embodiment, the inner diameter of the first recess 160 is made larger than the inner diameter of the second recess 260. Thereby, while moving the dielectric substrate 100 downward, it becomes possible to easily insert each conductive member 400 inside the first recess 160.

[0049] Also, if the inner diameter of the second recess 260 formed in the base plate 200 is larger than the inner diameter of the present embodiment, the gap between the inner peripheral surface 261 of the second recess 260 and the conductive member 400 becomes larger. As a result, it becomes difficult to make the conductive member 400 protrude perpendicularly from the surface 210 of the base plate 200. Further, since the position of the conductive member 400 in such a state is not accurately determined, alignment becomes difficult when the dielectric substrate 100 is brought closer to the lower base plate 200. Therefore, in the present embodiment, the inner diameter of the second recess 260 is made smaller than the inner diameter of the first recess 160 and is set to be approximately the same size as the outer diameter of the conductive member 400. Since a part of the conductive member 400 is inserted into the relatively small second recess 260, the conductive member 400 is prevented from falling or shifting in position. 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 the processing of the substrate W, there is a possibility that the portion of the dielectric substrate 100 near the conductive member 400 is excessively cooled by the base plate 200 via the conductive member 400. Further, when the amount of heat generated by the conductive member 400 increases due to energization of the RF electrode 140, there is also a possibility that the portion of the dielectric substrate 100 near the conductive member 400 is excessively heated by the conductive member 400. Such local cooling or heating by the conductive member 400 is considered to occur particularly easily when the inner peripheral surface 161 of the first recess 160 is in wide contact with the side surface of the conductive member 400, and as a result, the heat transfer between the two is large.

[0051] If local cooling or heating of the dielectric substrate 100 by the conductive member 400 is excessively performed, the variation in the in-plane temperature distribution of the substrate W during processing may increase. Therefore, in the electrostatic chuck 10 according to the present embodiment, the problem of the in-plane temperature distribution is also solved by devising the shapes of the first recess 160 and the second recess 260.

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

[0053] With such a configuration, it is possible to ensure a certain distance from the inner peripheral surface 161 of the first recess 160 to the side surface of the conductive member 400 over the entire circumference. Since a relatively large gap is formed between the inner peripheral surface 161 of the first recess 160 and the side surface of the conductive member 400, heat transfer between the two is reduced. As a result, local temperature rise or temperature drop is less likely to occur in the vicinity of the conductive member 400 in the dielectric substrate 100, so that variations in the in-plane temperature distribution of the substrate W during processing can be suppressed.

[0054] When the workability at the time of joining described above does not pose a problem, the diameter of the inner peripheral surface 261 of the second recess 260 may be larger than the diameter of the main body portion 410 of the conductive member 400. Also in this case, the diameter of the inner peripheral surface 161 of the first recess 160 may be made even larger than the diameter of the inner peripheral surface 261 of the second recess 260.

[0055] In a top view, the inner peripheral surface 161 of the first recess 160 and the inner peripheral surface 261 of the second recess 260 may be in a state where they are 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 peripheral surface 161 of the first recess 160 and the inner peripheral 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. Also in this case, it is preferable to form each of the first recess 160 and the second recess 260 such that the distance from the inner peripheral surface 161 of the first recess 160 to the side surface of the conductive member 400 is larger than the distance from the inner peripheral surface 261 of the second recess 260 to the side surface of the conductive member 400 over the entire circumference.

[0057] A second embodiment will be described. Hereinafter, differences from the first embodiment will be mainly described, and descriptions of points common to the first embodiment will be omitted as appropriate.

[0058] In FIG. 5, the configuration of the electrostatic chuck 10 according to the present embodiment is depicted from the same perspective as in FIG. 2. As shown in FIG. 5, the first recess 160 of the present embodiment is not formed to a depth position that exposes the RF electrode 140. The bottom surface 162 of the first recess 160 is located on the surface 120 side with respect to the RF electrode 140.

[0059] The bottom surface 162 of the first recess 160 is covered by a metal plate 141. The metal plate 141 is, for example, a plate-shaped member formed of molybdenum and is in close contact with substantially the entire bottom surface 162. The tip of the protruding portion 420 is pressed against the metal plate 141 in the present embodiment.

[0060] The space between the metal plate 141 and the RF electrode 140 is electrically connected by a plurality of via portions 142 provided in the dielectric substrate 100. The via portion 142 is filled with a conductive member such as tungsten inside a hole formed to extend along a direction perpendicular to the surface 120. One end of the via portion 142 is connected to the metal plate 141, and the other end is connected to the RF electrode 140.

[0061] Thus, in this embodiment, there is no direct connection between the conductive member 400 and the RF electrode 140. Instead, they are indirectly connected via the metal plate 141 and the via portion 142. Even in such a configuration, the same effects as those described in the first embodiment can be achieved.

[0062] The third embodiment will be described below. Hereinafter, the differences from the first embodiment will be mainly described, and the description of the points common to the first embodiment will be omitted as appropriate.

[0063] FIG. 6 depicts 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 peripheral surface 161 of the first recess 160 is approximately equal to the diameter of the main body portion 410 of the conductive member 400. On the other hand, the diameter of the inner peripheral surface 261 of the second recess 260 is larger than the diameter of the inner peripheral 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 peripheral surface 261 of the second recess 260 is located outside the inner peripheral surface 161 of the first recess 160 over the entire circumference.

[0064] The shape of the conductive member 400 is the same as that 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] Regarding the method of joining the dielectric substrate 100 and the base plate 200 in the manufacturing method of the electrostatic chuck 10 according to this embodiment, it will be described with reference to FIG. 7. In this figure, the configurations of the dielectric substrate 100, the base plate 200, and the conductive member 400 are schematically drawn in a simplified manner.

[0066] First, place the dielectric substrate 100 on a workbench (not shown) with the surface 120 facing upward. A first recess 160 is formed in the surface 120 in advance. Also, an adhesive that will become the bonding layer 300 after curing is applied in advance over substantially the entire surface 120. In FIG. 7, illustration of the adhesive is omitted. The adhesive may be applied in advance toward the surface 210 of the base plate 200.

[0067] Subsequently, insert the conductive members 400 into the respective first recesses 160. As shown in FIG. 7, a part of each conductive member 400 protrudes vertically from the surface 120 of the dielectric substrate 100.

[0068] Thereafter, bring the base plate 200 closer to the surface 120 from above with the surface 210 facing downward. A second recess 260 is formed in the surface 210 in advance. Also, the dielectric substrate 100 and the base plate 200 are aligned with each other such that each second recess 260 is directly above each first recess 160. While moving the base plate 200 along the arrow in FIG. 7, bond it to the dielectric substrate 100. When the movement is completed, each conductive member 400 is in a state of being accommodated inside the first recess 160 and the second recess 260. Thereafter, by heating the whole and curing the above-mentioned adhesive, the electrostatic chuck 10 according to the present embodiment is completed.

[0069] If the inner diameter of the second recess 260 formed in the base plate 200 is smaller than the inner diameter of the present embodiment, for example, if it is about the same as the inner diameter of the first recess 160, it becomes difficult to align when bringing the base plate 200 closer to the lower dielectric substrate 100. That is, it becomes difficult to insert each conductive member 400 inside the second recess 260. Therefore, in the present embodiment, the inner diameter of the second recess 260 is made larger than the inner diameter of the first recess 160. Thereby, while moving the dielectric substrate 100 downward, it becomes possible to easily insert each conductive member 400 inside the second recess 260.

[0070] Also, if the inner diameter of the first recess 160 formed in the dielectric substrate 100 is larger than the inner diameter of the present embodiment, the gap between the inner peripheral surface 161 of the first recess 160 and the conductive member 400 becomes larger. As a result, it becomes difficult to make the conductive member 400 protrude perpendicularly from the surface 120 of the dielectric substrate 100. Further, since the position of the conductive member 400 in such a state is not accurately determined, alignment becomes difficult when the base plate 200 is brought closer to the lower dielectric substrate 100. Therefore, in the present embodiment, the inner diameter of the first recess 160 is made smaller than the inner diameter of the second recess 260 and is set to be approximately the same size as the outer diameter of the conductive member 400. Since a part of the conductive member 400 is inserted into the relatively small first recess 160, the conductive member 400 is prevented from falling over or shifting in position. As a result, the above-described bonding operation during the manufacture of the electrostatic chuck 10 can be easily performed.

[0071] Thus, even in a configuration in which the size relationship between the first recess 160 and the second recess 260 in a top view is opposite to that of the first embodiment, the same effects as those described in the first embodiment can be achieved. Regarding which of the first recess 160 and the second recess 260 should be made larger, it may be determined according to which member is to be disposed on the lower side when the dielectric substrate 100 and the base plate 200 are joined.

[0072] The fourth embodiment will be described. Hereinafter, differences from the above-described third embodiment will be mainly described, and descriptions of points common to the third embodiment will be omitted as appropriate.

[0073] FIG. 8 depicts the configuration of the electrostatic chuck 10 according to the present embodiment from the same perspective as FIG. 6. As shown in FIG. 8, the first recess 160 of the present embodiment is not formed to a depth position 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.

[0074] 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 formed of, for example, molybdenum, and is in close contact with substantially the entire bottom surface 162. The tip of the protruding portion 420 is pressed against the metal plate 141 in this embodiment.

[0075] Between the metal plate 141 and the RF electrode 140, they are electrically connected by a plurality of via portions 142 provided in the dielectric substrate 100. The via portion 142 is filled with a conductive member such as tungsten inside a hole formed to extend along a direction perpendicular to the surface 120. One end of the via portion 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, but are indirectly connected via the metal plate 141 and the via portion 142. Even in such a mode, the same effects as those described in the third embodiment are achieved.

[0077] As described above, this embodiment has been described with reference to specific examples. However, the present disclosure is not limited to these specific examples. Those obtained by appropriately making design changes by those skilled in the art to these specific examples are also included in the scope of the present disclosure as long as they have the features of the present disclosure. Each element included in each of the above-described specific examples and its arrangement, conditions, shape, etc. are not limited to those illustrated and can be changed as appropriate. Each element included in each of the above-described specific examples can be appropriately combined as long as no technical contradiction occurs.

Description of Reference Numerals

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

Claims

1. A dielectric substrate having a placement surface on which an object to be adsorbed is placed, an internal electrode provided inside the dielectric substrate, a base plate formed of metal and joined to the dielectric substrate, and a conductive member that electrically connects between the internal electrode and the base plate, and includes: a first recess for accommodating a part of the conductive member is formed on the surface of the dielectric substrate on the base plate side, a second recess for accommodating a part of the conductive member is formed on the surface of the base plate on the dielectric substrate side, An electrostatic chuck, characterized in that when viewed from a direction perpendicular to the placement surface, one of the first recess and the second recess is larger than the other.

2. The electrostatic chuck according to claim 1, characterized in that when viewed from a direction perpendicular to the placement surface, the first recess is larger than the second recess.

3. When viewed from a direction perpendicular to the placement surface, The electrostatic chuck according to claim 2, characterized in that the inner peripheral surface of the first recess is outside the inner peripheral surface of the second recess over the entire circumference.

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

5. The electrostatic chuck according to claim 1, characterized in that when viewed from a direction perpendicular to the placement surface, the second recess is larger than the first recess.

6. When viewed from a direction perpendicular to the placement surface, The electrostatic chuck according to claim 5, characterized in that the inner peripheral surface of the second recess is outside the inner peripheral surface of the first recess over the entire circumference.

7. When viewed from a direction perpendicular to the placement surface, The electrostatic chuck according to claim 6, characterized in that the diameter of the portion of the conductive member accommodated in the first recess is equal to the diameter of the portion of the conductive member accommodated in the second recess.

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