Electrostatic chuck

Abstract

To provide an electrostatic chuck capable of easily realizing electrical connection between an internal electrode and a power supply terminal.SOLUTION: The electrostatic chuck 10 includes a dielectric substrate 100, an RF electrode 140 provided inside the dielectric substrate 100, a power supply terminal 170 disposed inside a recessed part 160 formed on a surface 120 opposite to a mounting surface of the dielectric substrate 100, and a connection part 190 electrically connecting the RF electrode 140 and the power supply terminal 170. The connecting portion 190 extends from the bottom surface 161 of the recessed portion 160 toward the placement surface side, and extends to a position closer to the placement surface side than the RF electrode 140.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] For example, semiconductor manufacturing equipment such as an etching device 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 supporting 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] An internal electrode is provided inside the dielectric substrate. The "internal electrode" is, for example, the above-mentioned attraction electrode. In addition, an RF electrode, which is one of a pair of opposing electrodes for generating plasma in semiconductor manufacturing equipment, may also be provided inside the dielectric substrate as the "internal electrode."

[0004] The dielectric substrate is further provided with a power supply terminal. The power supply terminal is a conductive member for receiving power from the outside to be supplied to the internal electrode. As described in Patent Document 1 below, the power supply terminal is often disposed inside a recess formed on the surface of the dielectric substrate opposite the mounting surface. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7184034 Summary of the Invention [Problem to be solved by the invention]

[0006] A specific configuration for electrically connecting the internal electrode and the power supply terminal is, for example, to form the recess so that the internal electrode is exposed at the bottom, and to connect the power supply terminal located inside the recess directly to the exposed internal electrode. However, such a configuration requires precise adjustment of the depth of the recess, which makes it extremely difficult to process the recess.

[0007] 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 easily realize an electrical connection between an internal electrode and a power supply terminal. [Means for solving the problem]

[0008] 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 power supply terminal disposed inside a recess formed in a surface of the dielectric substrate opposite the mounting surface, and a connecting portion that electrically connects the internal electrode and the power supply terminal. The connecting portion extends from a bottom surface of the recess toward the mounting surface, to a position closer to the mounting surface than the internal electrode.

[0009] When manufacturing an electrostatic chuck having the above configuration, a first recess is formed in a dielectric substrate to a depth position in front of the internal electrode, a second recess is formed from the bottom surface of the first recess to a position beyond the internal electrode, and a conductor serving as a connection portion is disposed inside the second recess. When processing either the first recess or the second recess, there is no need to precisely adjust the depth. Therefore, electrical connection between the internal electrode and the power supply terminal can be easily achieved. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an electrostatic chuck that can easily realize an electrical connection between an internal electrode and a power supply terminal. [Brief explanation of the drawings]

[0011] [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 an enlarged view showing the configuration of a power supply terminal and its vicinity in the electrostatic chuck according to the first embodiment. FIG. [Figure 3] FIG. 1 is a diagram illustrating the power supply terminals, connection portions, etc., as viewed from a direction perpendicular to the mounting surface. [Figure 4] 3A to 3C are diagrams for explaining a method for manufacturing an electrostatic chuck according to the first embodiment. [Figure 5] 3A to 3C are diagrams for explaining a method for manufacturing an electrostatic chuck according to the first embodiment. [Figure 6] 3A to 3C are diagrams for explaining a method for manufacturing an electrostatic chuck according to the first embodiment. [Figure 7] 10 is an enlarged view showing the configuration of the tip portion of the connection portion and its surrounding area. FIG. [Figure 8] FIG. 10 is a cross-sectional view schematically showing the configuration of an electrostatic chuck according to a second embodiment. [Figure 9] FIG. 10 is a perspective view showing the configuration of a connecting member included in the electrostatic chuck according to the second embodiment. [Figure 10] FIG. 10 is a diagram showing the configuration of an electrostatic chuck according to a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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."

[0017] 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 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.

[0018] In addition to the above-described attracting electrode 130, an RF electrode 140 is also embedded inside the dielectric substrate 100. The RF electrode 140 is provided as one of a pair of opposing electrodes for generating plasma in the semiconductor manufacturing 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.

[0019] 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, the RF electrode 140 may also be made of molybdenum, platinum, palladium, or the like. The RF electrode 140 is embedded in a position closer to the surface 120 than the chucking electrode 130. Like the chucking electrode 130, the RF electrode 140 is disposed parallel to the surface 110. The RF electrode 140 is a single electrode that is substantially circular in top view. The RF electrode 140 corresponds to the "internal electrode" in this embodiment.

[0020] Power is supplied from an external power source to the RF electrode 140 via the power supply member 14 and the power supply terminal 170. The power supply member 14 is a rod-shaped conductive member electrically connected to an external power source (not shown). The power supply member 14 is held by a holding mechanism (not shown) with its tip abutting against the power supply terminal 170. The power supply member 14 may be configured as a member that can expand and contract by elastic deformation. Only one power supply member 14 may be connected to the electrostatic chuck 10, or multiple power supply members 14 may be connected.

[0021] The power supply terminal 170 is a terminal provided on the dielectric substrate 100 as a portion for receiving power supplied to the RF electrode 140. The power supply terminal 170 is a substantially disk-shaped member made of a conductive member such as a metal. The power supply terminal 170 is made of a material containing molybdenum, for example.

[0022] A recess 160 is formed on a surface 120 of the dielectric substrate 100 opposite to the mounting surface. The power supply terminal 170 is disposed inside the recess 160 and is electrically connected to the RF electrode 140 via a connection portion 190, which will be described later. The specific configuration of the power supply terminal 170 and its surrounding area will be described later.

[0023] A space SP is formed between the dielectric substrate 100 and the substrate W. When processing such as etching is performed in the semiconductor manufacturing equipment, helium gas for temperature adjustment is supplied to the space SP from the outside through a gas hole (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 type of gas other than helium.

[0024] 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.

[0025] The seal ring 111 is a wall that divides the space SP at the outermost position. The upper end of the seal ring 111 forms part of the surface 110 and abuts against the substrate W. Note that multiple seal rings 111 may be provided to divide the space SP. With this configuration, it is possible to individually adjust the pressure of the helium gas in each space SP and make the surface temperature distribution of the substrate W during processing more uniform.

[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 upper end 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 dielectric substrate 100 of this embodiment is provided with a flange 150. The flange 150 is a portion that protrudes further outward than the surface 110, which is the mounting surface. In a top view, the flange 150 surrounds the entire surface 110 from the outside. The surface of the flange 150 facing the substrate W (the upper surface in FIG. 1 ) is located closer to the base plate 200 than the surface 110 (the lower side in FIG. 1 ). When processing the substrate W, an annular member (not shown), such as a "focus ring," is placed on the flange 150. Alternatively, the dielectric substrate 100 may not be provided with the flange 150, and the annular member may be placed directly on the base plate 200.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] A through hole 260 is formed in the base plate 200. The through hole 260 is a hole provided for inserting the previously described power supply member 14, and is formed to penetrate the base plate 200 vertically from the surface 210 to the surface 220. A cylindrical member may be disposed between the inner surface of the through hole 260 and the power supply member 14 to prevent discharge from occurring between them.

[0034] Fig. 2 shows a specific configuration of the power supply terminal 170 and its vicinity in the electrostatic chuck 10 shown in Fig. 1. Note that the power supply member 14 is not shown in Fig. 2.

[0035] As described above, the recess 160 is formed on the surface 120 of the dielectric substrate 100. The outer shape of the recess 160 is circular when viewed from above. The recess 160 is a bottomed hole that is formed so as to recede from the surface 120 toward the surface 110. The diameter of the recess 160 when viewed from above (which can also be said to be the inner diameter of the recess 160) is slightly larger than the outer diameter of the power supply terminal 170 when viewed from above.

[0036] The bottom surface of the recess 160, i.e., the surface of the recess 160 closest to the surface 110, will hereinafter also be referred to as the "bottom surface 161." The power supply terminal 170 is joined to the bottom surface 161 of the recess 160 via a brazing material 180. The brazing material 180 is, for example, a silver brazing material to which titanium has been added, and can be brazed directly to the surface of the ceramic dielectric substrate 100. The brazing material 180 may contain copper or the like in addition to silver and titanium.

[0037] The position of the bottom surface 161, i.e., the position where the power supply terminal 170 is joined, is closer to the surface 120 than the RF electrode 140. The RF electrode 140 and the power supply terminal 170 are electrically connected via a connection portion 190. The connection portion 190 is formed to extend from the bottom surface 161 of the recess 160 toward the surface 110 (upward in FIG. 2 ), and extends to a position closer to the surface 110 than the RF electrode 140. That is, the connection portion 190 penetrates the RF electrode 140 and is electrically connected to the RF electrode 140. The lower end of the connection portion 190 in FIG. 2 is connected to the brazing filler metal 180. In this embodiment, the material of the connection portion 190 and the material of the brazing filler metal 180 are the same, and the two are integrally connected. With the above-described configuration, the RF electrode 140 and the power supply terminal 170 are electrically connected via the brazing filler metal 180 and the connection portion 190.

[0038] 3 is a schematic diagram of the portion of the dielectric substrate 100 where the recess 160 is formed, as viewed from the surface 120 side. In the figure, the connection portion 190, which is located on the back side of the paper relative to the power supply terminal 170, is depicted by a dotted line. In this embodiment, multiple connection portions 190 are connected to one power supply terminal 170. When viewed from above, each connection portion 190 has a circular shape.

[0039] In top view, the multiple connection portions 190 are arranged so as to be lined up in a circle inside the recess 160. The circular dashed-dotted line DL shown in Fig. 3 represents an imaginary circle that passes through the center of each connection portion 190 in top view. In other words, the multiple connection portions 190 are arranged so as to be lined up along the circle of the dashed-dotted line DL. The center of the circle in top view coincides with the center of the recess 160.

[0040] Furthermore, in this embodiment, the multiple connection portions 190 are arranged so as to be evenly spaced along the circle indicated by the dashed-dotted line DL. The "space" here refers to the length along the dashed-dotted line DL between a pair of adjacent connection portions 190. All of the multiple connection portions 190 may be arranged evenly spaced along the circle indicated by the dashed-dotted line DL, or only some of the multiple connection portions 190 may be arranged evenly spaced along the circle indicated by the dashed-dotted line DL.

[0041] It should be noted that another connecting portion 190 may be provided at a position different from the above. For example, a connecting portion 190 may be provided separately at a position that is the center of the circle indicated by the dashed dotted line DL in top view.

[0042] Among the methods for manufacturing the electrostatic chuck 10, a method for forming the connection portion 190 and the like will be described below. First, the dielectric substrate 100 having the built-in attraction electrode 130 and RF electrode 140 is manufactured. As the manufacturing method, various conventionally known methods such as sheet lamination can be used.

[0043] After the firing of the dielectric substrate 100 is completed, a recess 160 is formed on the surface 120. FIG. 4 shows a cross section of the dielectric substrate 100 at the time when the formation of the recess 160 is completed. The recess 160 is not formed to a depth that reaches the RF electrode 140. As described above, the position of the bottom surface 161 of the recess 160 is closer to the surface 120 than the RF electrode 140. Therefore, the RF electrode 140 is not exposed on the inner surface of the recess 160.

[0044] Next, a plurality of recesses 162 are formed so as to extend further from the bottom surface 161 of the recess 160 toward the surface 110. Figure 5 shows the state after the formation of the recesses 162 is completed. The recesses 162 are portions that will later become the connection portions 190. When viewed from above, each recess 162 has a circular shape.

[0045] The bottom surface of the recess 162, that is, the surface of the recess 162 closest to the surface 110, will hereinafter also be referred to as the "bottom surface 163." When the processing of the recess 162 is complete, the bottom surface 163 is located closer to the surface 110 than the RF electrode 140. That is, each recess 162 is formed to extend to a depth that penetrates the RF electrode 140. Therefore, the RF electrode 140 is exposed on the inner surface of the recess 162.

[0046] 6, first, the brazing filler metal 180 is placed on the bottom surface 161 of the recess 160, and then the power supply terminal 170 is placed thereon. The brazing filler metal 180 is a plate-like brazing filler metal 180 that has been processed into a circular shape before melting. It is also possible to apply the brazing filler metal 180 in a paste form to the bottom surface 161. At this stage, the brazing filler metal 180 has not yet entered the recess 162, so a space is formed inside the recess 162.

[0047] 6, the entire dielectric substrate 100 is heated, for example, in a vacuum furnace. As a result, the bottom surface 161, the power supply terminal 170, etc. become wet with the molten brazing material 180. A portion of the molten brazing material 180 enters the inside of the recess 162. The inside of the recess 162 becomes filled with the brazing material 180, and the RF electrode 140 exposed on the inner surface of the recess 162 and the brazing material 180 become connected to each other.

[0048] When the heating in the vacuum furnace is completed, the brazing material 180 that has entered the inside of the recess 162 solidifies to form the connection portion 190. This completes the electrostatic chuck 10 having the configuration shown in FIG.

[0049] 7 shows an enlarged view of the configuration of the portion of the connection part 190 that penetrates the RF electrode 140. "L" shown in the figure represents the amount of protrusion of the connection part 190 from the RF electrode 140. Hereinafter, this amount of protrusion will also be referred to as "protrusion amount L." Protrusion amount L is the distance along the direction perpendicular to the surface 110 from the end of the connection part 190 on the surface 110 side (the upper side in FIG. 7) to the surface of the RF electrode 140 on the surface 110 side.

[0050] 7, the outer periphery of the tip of connecting portion 190 is rounded. Therefore, the diameter of connecting portion 190 is slightly smaller at the tip than at other portions. Such a shape of connecting portion 190 results from the shape of the tool used to machine recess 162.

[0051] If the protrusion amount L is too small, the diameter of the portion of the connection portion 190 that penetrates the RF electrode 140 may become small. Such a configuration is undesirable because the electrical resistance between the connection portion 190 and the RF electrode 140 becomes smaller than the designed value. To make the electrical resistance match the designed value, the protrusion amount L should be sufficiently large. Specifically, the protrusion amount L should be large enough so that the diameter D1 of the portion of the connection portion 190 closer to the surface 120 than the RF electrode 140 and the diameter D2 of the portion of the connection portion 190 closer to the surface 110 than the RF electrode 140 are approximately equal to each other. For example, it is preferable to ensure that the protrusion amount L is 50 μm or more.

[0052] If the electrical resistance between the connection portion 190 and the RF electrode 140 does not pose a particular problem, the diameter D2 may be equal to or smaller than the diameter D1.

[0053] In order to explain the advantages of the configuration of this embodiment as described above, a configuration according to a comparative example will first be described with reference to Fig. 10. As shown in the figure, in this comparative example, a recess 160 is formed so that the RF electrode 140 is exposed at the bottom surface 161. Furthermore, a power supply terminal 170 is directly joined to the exposed RF electrode 140 via a brazing material 180.

[0054] Even in such a comparative example configuration, it is possible to electrically connect the RF electrode 140 and the power supply terminal 170. However, when forming the recess 160 in the dielectric substrate 100, it is necessary to precisely adjust the depth of the recess 160 so that the relatively thin RF electrode 140 is exposed over the entire bottom surface 161. This poses a problem in that processing the recess 160 is extremely difficult.

[0055] Therefore, in the electrostatic chuck 10 according to this embodiment, the configuration shown in FIG. 2 is adopted, thereby eliminating the need to precisely adjust the depth of the recess 160.

[0056] 4, the recess 160 in this embodiment is not formed to a depth that reaches the RF electrode 140. Since it is not necessary to precisely adjust the position of the bottom surface 161 of the recess 160 so that the RF electrode 140 is exposed, the recess 160 can be formed relatively easily.

[0057] The same applies to the formation of recess 162 shown in Fig. 5. Since it is not necessary to precisely adjust the position of bottom surface 163 of recess 162 so that RF electrode 140 is exposed, recess 162 can be formed relatively easily.

[0058] As described above, when manufacturing the electrostatic chuck 10 according to this embodiment, there is no need to precisely adjust the depth when processing either the recess 160 or the recess 162. Therefore, electrical connection between the RF electrode 140 and the power supply terminal 170 can be easily achieved.

[0059] In this embodiment, by providing multiple connection portions 190 for one power supply terminal 170, the electrical resistance between the power supply terminal 170 and the RF electrode 140 is kept low. Furthermore, since the multiple connection portions 190 are arranged at equal intervals along a circle when viewed from above, current does not flow unevenly through some of the connection portions 190. Since current flows roughly evenly through the multiple connection portions 190, localized heat generation can be prevented.

[0060] In this embodiment, when the bottom surface 161 and the power supply terminal 170 are joined with the brazing filler metal 180, a part of the brazing filler metal 180 enters the recess 162 to form the connection portion 190. Therefore, the connection portion 190 can be easily formed.

[0061] The material of the connecting portion 190 and the material of the brazing material 180 may be the same as in this embodiment, but may also be different materials.

[0062] In general, the materials for the RF electrode 140 and the chucking electrode 130, which are internal electrodes, must be selected taking into consideration shrinkage that occurs when the dielectric substrate 100 is fired, and therefore there are restrictions, such as the difficulty of achieving a sufficiently low electrical resistivity. Furthermore, when air firing is performed, there is also a restriction that only materials that are resistant to oxidation can be used as the materials for the RF electrode 140, etc.

[0063] On the other hand, since the connection portion 190 is formed after firing, the material of the connection portion 190 can be freely selected without considering the above-mentioned constraints. Therefore, in this embodiment, a material different from the material of the RF electrode 140 is used as the material of the connection portion 190. Specifically, a material (e.g., silver) having a lower electrical resistivity than the material (e.g., tungsten) of the RF electrode 140 is used as the material of the connection portion 190. In addition, since a material with a melting point lower than the firing temperature of ceramics can be used as the material of the connection portion 190, there is also the advantage that residual stress can be reduced when the temperature returns to room temperature.

[0064] The configuration for supplying power to the RF electrode 140 as described above, i.e., a configuration similar to the configuration including the recess 160, the power supply terminal 170, and the connection portion 190, etc., may be applied to the configuration for supplying power to the chucking electrode 130.

[0065] 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.

[0066] Fig. 8 is a schematic cross-sectional view of the electrostatic chuck 10 according to this embodiment, similar to Fig. 1. In this embodiment, power is supplied to the RF electrode 140 via a base plate 200 and a connection member 400, rather than via the power supply member 14.

[0067] The connection member 400 is a member for electrically connecting the RF electrode 140 and the base plate 200. The connection 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. The potential of the base plate 200 is adjusted by, for example, an external power supply.

[0068] In this embodiment, no through-hole 260 is formed in the base plate 200. Therefore, the inside of the recess 160 is a closed space. The connection member 400 is disposed in this closed space.

[0069] The connecting member 400 is a substantially cylindrical member made of a fibrous metal member, and is housed inside the recess 160. One end of the connecting member 400 abuts against the power supply terminal 170 arranged in the recess 160. The other end of the connecting member 400 abuts against the surface 210 of the base plate 200. The power supply terminal 170 and the base plate 200 are electrically connected by the connecting member 400 arranged in this manner. A recess, which is a bottomed hole, may be formed in the surface 210 of the base plate 200 at a position directly below the recess 160, and a portion of the connecting member 400 may be housed in this recess.

[0070] 9, the connecting member 400 has a substantially cylindrical main body 410 and a plurality of protruding portions 420, the entirety of which is integrally formed from a fibrous metal material. 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.

[0071] The connecting member 400, which is made of a fibrous metal member, has sufficient breathability to allow fluids such as air and adhesive to penetrate inside. In other words, the fibrous metal member is not dense enough, and there are gaps between the fibers. With this configuration, each part of the connecting member 400, including the protruding portion 420, is an elastic body that can easily deform when subjected to an external force.

[0072] When not subjected to an external force, the dimension of connecting member 400 in the up-down direction (the direction in which protrusions 420 extend) is larger than the dimension in the same direction in the state shown in Fig. 1. In other words, connecting member 400 is housed inside recess 160 in a state compressed in the direction from dielectric substrate 100 to base plate 200, and is sandwiched between power supply terminal 170 and surface 210. The tip of each protrusion 420 is elastically deformed so as to be crushed when pressed against power supply terminal 170.

[0073] The connecting member 400 is pressed against the power supply terminal 170 and the surface 210 by its own restoring force. Therefore, even if thermal expansion or contraction occurs in each part of the electrostatic chuck 10 during processing of the substrate W, the electrical connection between the power supply terminal 170 and the surface 210 is always maintained.

[0074] A shape different from that of this embodiment may be adopted as the shape of the connection member 400. For example, the entire connection member 400 may be substantially cylindrical, and may not have the protrusion 420.

[0075] Even in the case of this embodiment where the power supply terminal 170 and the base plate 200 are electrically connected via the connection member 400, the same effects as those described in the first embodiment can be achieved.

[0076] 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]

[0077] 10: Electrostatic chuck 110,120: face 140:RF electrode 160: Recess 161: Bottom 170: Power supply terminal 180: Brazing material 190: Connection part 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 power supply terminal disposed inside a recess formed on a surface of the dielectric substrate opposite to the mounting surface; a connection portion that electrically connects the internal electrode and the power supply terminal, The electrostatic chuck is characterized in that the connection portion extends from the bottom surface of the recess toward the mounting surface side, and extends to a position that is closer to the mounting surface than the internal electrode.

2. 2. The electrostatic chuck according to claim 1, wherein a plurality of said connection portions are connected to one of said power supply terminals.

3. When viewed from a direction perpendicular to the placement surface, The recess has a circular outer shape, 3. The electrostatic chuck according to claim 2, wherein a plurality of said connection portions are arranged in a circle.

4. When viewed from a direction perpendicular to the placement surface, 4. The electrostatic chuck according to claim 3, wherein a plurality of said connection portions are arranged at equal intervals along a circle.

5. 2. The electrostatic chuck according to claim 1, wherein the bottom surface of the recess and the power supply terminal are joined together via a brazing material.

6. 6. The electrostatic chuck according to claim 5, wherein the material of the connecting portion and the material of the brazing material are the same.

7. 7. The electrostatic chuck according to claim 6, wherein the material of the connection portion is different from the material of the internal electrode.

8. 8. The electrostatic chuck according to claim 7, wherein the electrical resistivity of the material of the connection portion is lower than the electrical resistivity of the material of the internal electrode.

9. 9. The electrostatic chuck according to claim 8, wherein the material of the connecting portion and the material of the brazing material both contain silver.

10. 2. The electrostatic chuck according to claim 1, wherein the connecting portion protrudes from the internal electrode by an amount of 50 [mu]m or more.

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