Electrostatic chuck

Abstract

To provide an electrostatic chuck capable of preventing discharge between a power supply member and a base plate.SOLUTION: The electrostatic chuck 10 includes a dielectric substrate 100, an internal electrode 140 provided inside the dielectric substrate 100, a base plate 200 in which a through hole 230 is formed, a power supply member 400 which is a member for supplying power to the internal electrode 140 and is inserted into the through hole 230, and an insulating member 500 disposed between an inner surface of the through hole 230 and the power supply member 400. The insulating member 500 includes a cylindrical first insulating member 510 and a cylindrical second insulating member 520 covering a part of the first insulating member 510 from the outer peripheral side. The electrostatic chuck 10 further includes an annular member 530 for preventing discharge along a path from the power supply member 400 to the inner surface of the through hole 230 through a space between the first insulating member 510 and the second insulating member 520.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 an etching apparatus 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 having an attracting electrode therein and a base plate for supporting the dielectric substrate, which are joined together. When a voltage is applied to the attracting electrode, an electrostatic force is generated, attracting and holding a substrate placed on the dielectric substrate.

[0003] An RF electrode may also be provided inside the dielectric substrate. The RF electrode is used as one of a pair of opposing electrodes to generate plasma in semiconductor manufacturing equipment. An external voltage is also applied to the RF electrode.

[0004] Electrodes provided inside the dielectric substrate, such as the above-mentioned chucking electrode and RF electrode, are hereinafter collectively referred to as "internal electrodes." As described in Patent Document 1 listed below, the electrostatic chuck is provided with a power supply member for supplying power to the internal electrodes. The power supply member is inserted into a through hole that penetrates the base plate and is electrically connected to the internal electrodes of the dielectric substrate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-222748 Summary of the Invention [Problem to be solved by the invention]

[0006] To prevent discharge between the power supply member and the through hole in the base plate, it is preferable that the entire inner surface of the through hole in the base plate, from its top end to its bottom end, be covered with an insulating member. The inventors have been studying a configuration in which the insulating member is a cylindrical first insulating member and a cylindrical second insulating member that covers a portion of the first insulating member from the outer periphery. By configuring the two cylindrical members to overlap each other, it is possible to easily and reliably cover the entire inner surface of the through hole in the base plate, even if there is variation in the dimensions of each member.

[0007] However, with the above configuration, there is a possibility that discharge may occur between the power supply member and the base plate via a path that passes through the gap between the first insulating member and the second insulating member.

[0008] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an electrostatic chuck that can prevent discharge between a power supply member and a base plate. [Means for solving the problem]

[0009] To achieve the above object, an electrostatic chuck according to the present invention includes a dielectric substrate having a mounting surface on which an object to be attracted is placed, an internal electrode provided inside the dielectric substrate, a metal member supporting the dielectric substrate, a base plate having a through hole formed therein, a power supply member for supplying power to the internal electrode, the power supply member being inserted through the through hole, and an insulating member disposed between the inner surface of the through hole and the power supply member. The insulating member includes a cylindrical first insulating member and a cylindrical second insulating member outer circumferentially covering a portion of the first insulating member, and the first insulating member and the second insulating member cover the inner surface of the through hole from one end to the other end. The electrostatic chuck further includes a discharge prevention member for preventing discharge along a path from the power supply member, passing between the first insulating member and the second insulating member, to the inner surface of the through hole.

[0010] In the electrostatic chuck having the above configuration, even though the insulating members include the first insulating member and the second insulating member, the discharge prevention member can reliably prevent discharge along the path passing between the two members. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an electrostatic chuck that can prevent discharge between a power supply member and a base plate. [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] FIG. 2 is an enlarged view showing a partial configuration of the electrostatic chuck according to the first embodiment. [Figure 3] FIG. 10 is a diagram for explaining a discharge path in an electrostatic chuck according to a comparative example. [Figure 4] FIG. 10 is an enlarged view showing a partial configuration of an electrostatic chuck according to a second embodiment. [Figure 5] FIG. 10 is an enlarged view showing a partial configuration of an electrostatic chuck according to a third embodiment. [Figure 6] FIG. 10 is an enlarged view showing a partial configuration of an electrostatic chuck according to a fourth embodiment. [Figure 7] FIG. 10 is an enlarged view showing a partial configuration of an electrostatic chuck according to a fifth 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 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 described later. 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 internal electrode 140 is provided inside the dielectric substrate 100. The internal electrode 140 is a thin, flat layer made of a metal material such as tungsten, and is arranged parallel to the surface 110. In addition to tungsten, the internal electrode 140 may be made of molybdenum, platinum, palladium, or the like. The internal electrode 140 is also called an "RF electrode" and is used as one of a pair of opposing electrodes for generating plasma in a semiconductor manufacturing device. When power is supplied to the internal electrode 140 via a power supply member 400 (described later), plasma is generated and is attracted toward the substrate W. The power supply member 400 and its surrounding configuration will be described later.

[0019] In addition to the internal electrode 140, an adsorption electrode is also provided inside the dielectric substrate 100, but this is not shown in FIG. 1. The adsorption electrode is provided at a position closer to the surface 110 than the internal electrode 140. When a voltage is applied to the adsorption electrode (not shown) 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 adsorption electrode may be provided as an electrode separate from the internal electrode 140 as described above, or the internal electrode 140 may also be configured to serve as the adsorption electrode.

[0020] 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 apparatus, an inert gas for temperature adjustment is supplied to the space SP from the outside through a gas hole (not shown). By providing the inert 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. In this embodiment, helium gas is used as the inert gas for temperature adjustment supplied to the space SP, but a gas other than helium gas may also be used.

[0021] 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.

[0022] 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.

[0023] The portion marked with the reference numeral "116" in FIG. 1 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. The bottom surface 116 is parallel to the surface 110.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] The configuration of the power supply member 400 and its surroundings will be described mainly with reference to FIG. 2. As described above, the power supply member 400 is a member for supplying power to the internal electrode 140. The power supply member 400 is a rod-shaped member made of a conductive material such as metal. The upper end of the power supply member 400 in FIGS. 1 and 2 abuts against the internal electrode 140. The power supply member 400 protrudes toward the base plate 200 beyond the surface 120 of the dielectric substrate 100. A through hole 230 is formed in the base plate 200, and the power supply member 400 is inserted into the through hole 230.

[0030] 2, a circular recess 130 is formed on the surface 120 of the dielectric substrate 100, receding toward the internal electrode 140. The recess 130 is a hole with a bottom, and the internal electrode 140 is exposed at the bottom. The power supply member 400 is inserted into the recess 130, and one end of the power supply member 400 is pressed against the exposed internal electrode 140 as described above.

[0031] A recess 402 is formed in the end of the power supply member 400 opposite to the end pressed against the internal electrode 140. The recess 402 is a portion that receives a power supply pin (not shown) for supplying power from the outside. When processing is performed in the semiconductor manufacturing equipment, the power supply pin is inserted into the recess 402.

[0032] A male screw 405 is formed on the outer surface 401 of the power supply member 400 in a portion near the end where the recess 402 is formed. The male screw 405 is threadedly engaged with a female screw 525 formed on the insulating member 500 (described later). Therefore, by rotating the power supply member 400 around its central axis, the power supply member 400 can be moved along the central axis and one end of the power supply member 400 can be pressed against the internal electrode 140.

[0033] At this time, to prevent one end of the power supply member 400 from being pressed too hard against the internal electrode 140, the power supply member 400 may be provided with an expansion / contraction mechanism (not shown). That is, an expansion / contraction mechanism may be provided such that when one end of the power supply member 400 is pressed against the internal electrode 140, the total length of the power supply member 400 is shortened by the reaction force received from the internal electrode 140. In this case, if the power supply member 400 is configured to elastically return to its original length, the force applied from the power supply member 400 to the internal electrode 140 can be kept to an appropriate level. Instead of providing such an expansion / contraction mechanism, an elastic and conductive member may be interposed between the tip of the power supply member 400 and the internal electrode 140.

[0034] Alternatively, an electrode terminal electrically connected to the internal electrode 140 may be provided on the surface 120 of the dielectric substrate 100, and the tip of the power supply member 400 may be in contact with the electrode terminal. In other words, the power supply member 400 may not be in direct contact with the internal electrode 140.

[0035] As described above, a through hole 230 is formed in the base plate 200, and the power supply member 400 is inserted through this through hole 230. The through hole 230 is formed to penetrate vertically from the surface 210 to the surface 220 of the base plate 200. The cross-sectional shape of the through hole 230 at each height position from the surface 210 to the surface 220 is circular. However, the inner diameter of the through hole 230 is not constant throughout, but is different at each height position.

[0036] The inner surface of through hole 230 has a first inner surface 231, a second inner surface 232, and a third inner surface 233. The first inner surface 231 is the portion of the inner surface of through hole 230 closest to surface 210. The third inner surface 233 is the portion of the inner surface of through hole 230 closest to surface 220. The second inner surface 232 is the portion of the inner surface of through hole 230 between the first inner surface 231 and the third inner surface 233. The inner diameter of through hole 230 is generally constant in each portion. The inner diameter of second inner surface 232 is larger than the inner diameter of first inner surface 231, and the inner diameter of third inner surface 233 is even larger than the inner diameter of second inner surface 232.

[0037] An inner surface of through hole 230 that is between first inner surface 231 and second inner surface 232 and is parallel to surface 210 will also be referred to as "surface 234" below. Also, an inner surface of through hole 230 that is between second inner surface 232 and third inner surface 233 and is parallel to surface 210 will also be referred to as "surface 235" below.

[0038] The inner surface of the through hole 230 and the internal electrode 140 are both conductive and face each other. Therefore, when a voltage is applied to the power supply member 400, there is a concern that discharge may occur between them. Therefore, a cylindrical insulating member 500 is disposed between the inner surface of the through hole 230 and the internal electrode 140, thereby preventing such discharge. The insulating member 500 is made of an insulating material such as alumina or resin.

[0039] The insulating member 500 is not a single member as a whole, but includes a first insulating member 510 and a second insulating member 520, which are separate members. The first insulating member 510 and the second insulating member 520 are both substantially cylindrical in shape. The central axis of the first insulating member 510 and the central axis of the second insulating member 520 both coincide with the central axis of the internal electrode 140.

[0040] An end of the first insulating member 510 on the dielectric substrate 100 side abuts against the surface 120 of the dielectric substrate 100. An end 513 of the first insulating member 510 on the opposite side to the end mentioned above is located inside the base plate 200, that is, between the surface 210 and the surface 220. Therefore, the first insulating member 510 does not cover the entire inner surface of the through hole 230, but only covers the portion of the inner surface on the surface 210 side.

[0041] The power supply member 400 extends to a position closer to the surface 220 (lower in FIG. 2 ) than the end 513 of the first insulating member 510. The outer diameter of the first insulating member 510 is approximately the same as the inner diameter of the first inner surface 231 of the through hole 230. A small gap is formed between the inner surface 511 of the first insulating member 510 and the outer surface 401 of the internal electrode 140.

[0042] The portion marked with the reference symbol "514" in Fig. 2 is a portion of the outer surface 512 of the first insulating member 510 near the upper end. This portion will also be referred to as the "expanded diameter portion 514" below. The expanded diameter portion 514 has a tapered shape such that the outer diameter gradually increases as it approaches the surface 120 of the dielectric substrate 100. The shape of the first inner surface 231 in this portion also has a tapered shape corresponding to the expanded diameter portion 514.

[0043] The second insulating member 520 covers a portion of the first insulating member 510 from the outer periphery. The lower end of the second insulating member 520 in FIG. 2 is at the same height as the surface 220. The upper end 522 of the second insulating member 520 in FIG. 2 is located inside the base plate 200, that is, between the surface 210 and the surface 220. Therefore, the second insulating member 520 does not cover the entire inner surface of the through hole 230, but only covers the portion of the inner surface on the surface 220 side.

[0044] The end 522 of the second insulating member 520 is located closer to the surface 210 than the end 513 of the first insulating member 510 along the central axis of the through hole 230. In other words, the end 513 of the first insulating member 510 is located closer to the surface 220 than the end 522 of the second insulating member 520 along the central axis of the through hole 230.

[0045] In this manner, in this embodiment, first insulating member 510, which covers a portion of the inner surface of through hole 230 on the surface 210 side, and second insulating member 520, which covers a portion of the inner surface on the surface 220 side, are overlapped with each other, and these two members cover the entire inner surface of through hole 230. With this configuration, even if there is variation in the dimensions of each member such as first insulating member 510 (particularly, the dimensions in the vertical direction in FIG. 2), there will be no case where a portion of the inner surface of through hole 230 is not left uncovered by insulating member 500.

[0046] As described above, the first insulating member 510 and the second insulating member 520 cover the inner surface of the through hole 230, but "covering" here means that the inner surface of the through hole 230 does not directly face the power supply member 400. A gap may be formed between the inner surface of the through hole 230 and the first insulating member 510 or the second insulating member 520 that covers it.

[0047] An end 522 of the second insulating member 520 faces the surface 234 of the base plate 200, and a gap is formed between the end 522 and the surface 234. An annular member 530 is disposed in the gap. The annular member 530 is an electrically insulating member having elasticity, such as rubber, and has a circular ring shape. The annular member 530 is sandwiched between the end 522 and the surface 234 and is in a compressed state.

[0048] 2, the portion designated by the reference symbol "521" is the portion of the inner surface of the second insulating member 520 that faces the outer surface 512 of the first insulating member 510. This portion will also be referred to as the "inner surface 521" below. A small gap is formed between the inner surface 521 and the outer surface 512.

[0049] In FIG. 2 , the portion marked with the reference symbol "523" is a portion of the inner surface of the second insulating member 520 that directly faces the outer surface 401 of the power supply member 400 without the first insulating member 510 in between. This portion will also be referred to as the "inner surface 523" below. The inner diameter of the inner surface 523 is smaller than the inner diameter of the inner surface 521. A small gap is formed between the inner surface 523 and the outer surface 401. A female screw 525 is formed in a part of the inner surface 523. As described above, the female screw 525 is threadedly engaged with the male screw 405 formed on the outer surface 401 of the power supply member 400.

[0050] The inner surface of the second insulating member 520, which is between the inner side surface 521 and the inner side surface 523 and is parallel to the surface 210, will hereinafter also be referred to as "surface 524." The surface 524 faces the end portion 513 of the first insulating member 510. A gap is formed between the surface 524 and the end portion 513.

[0051] A flange 526, which is an expanded diameter portion, is provided at the end of the second insulating member 520 closest to the surface 220. The outer diameter of the flange 526 is approximately equal to the inner diameter of the third inner surface 233. The flange 526 abuts against the surface 235 from below, thereby determining the position of the second insulating member 520 in the up-down direction in Figure 2. The second insulating member 520 is fixed to the base plate 200 by, for example, press-fitting or adhesive.

[0052] As described above, in this embodiment, the first insulating member 510 and the second insulating member 520 cover the entire inner surface of the through hole 230 from one end of the through hole 230 to the other end.

[0053] However, in this configuration, there is a possibility that discharge may occur between the power supply member and the base plate along a path that passes through the gap between the first insulating member 510 and the second insulating member 520. Specifically, there is a possibility that discharge may occur from the power supply member 400 to the inner surface of the through hole 230 along a path such as that shown by the arrow AR in FIG.

[0054] Therefore, in this embodiment, an annular member 530 is sandwiched between the tip (end 522) of the second insulating member 520 and the surface 234 of the base plate 200, thereby preventing the occurrence of the above-mentioned discharge. The annular member 530 is an elastic member, and is compressed when sandwiched between the end 522 and the surface 234. Therefore, the annular member 530 closes the gap between the first insulating member 510 and the second insulating member 520 (specifically, the gap between the inner surface 521 and the outer surface 512), blocking a path through which discharge could occur. To reliably prevent discharge, it is preferable that the annular member 530 abuts against the outer surface 512 of the first insulating member 510 over the entire circumference. A configuration may also be adopted in which a portion of the compressed and deformed annular member 530 enters the gap between the inner surface 521 and the outer surface 512.

[0055] The annular member 530 is a member for preventing discharge along the path from the power supply member 400, passing between the first insulating member 510 and the second insulating member 520, to the inner surface of the through hole 230, and corresponds to the "discharge prevention member" in this embodiment.

[0056] Any elastic and electrically insulating material can be used as the material for the annular member 530. For example, materials such as silicone rubber and fluorine-based polymers can be used.

[0057] The configurations of the power supply member 400, insulating member 500, etc. described above may be applied not only to the power supply path connected to the internal electrode 140 (that is, the RF electrode) but also to the power supply path connected to the chucking electrode (not shown).

[0058] Furthermore, in this embodiment, the first insulating member 510 covers a portion of the inner surface of the through hole 230 that faces the surface 210, and the second insulating member 520 covers a portion of the inner surface of the through hole 230 that faces the surface 220. The positional relationship between the first insulating member 510 and the second insulating member 520 may be reversed from that described above. In other words, a configuration may be adopted in which the second insulating member 520 covers a portion of the inner surface of the through hole 230 that faces the surface 210, and the first insulating member 510 covers a portion of the inner surface of the through hole 230 that faces the surface 220.

[0059] The second 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.

[0060] FIG. 4 illustrates the configuration of the power supply member 400 and its surrounding area according to this embodiment, from the same perspective as FIG. 2 . In this embodiment, an annular member 540 is provided instead of the annular member 530. The annular member 540 is made of an elastic, electrically insulating material. The annular member 540 is a member that is fixed to the tip (end 522) of the second insulating member 520 before the second insulating member 520 is attached to the base plate 200. The annular member 540 is attached to the entire surface of the end 522, and therefore has an annular shape. Materials such as silicone rubber and fluorine-based polymers can be used as materials for the annular member 540. The annular member 540 may be fixed to the end 522 by adhesive or the like, or may be formed by applying a rubber coating to the end 522, for example.

[0061] When the second insulating member 520 is inserted into the through-hole 230, the annular member 540 is sandwiched and compressed between the end portion 522 and the surface 234 of the base plate 200. At this time, the deformed annular member 540 comes into contact with the outer surface 512 of the first insulating member 510 over the entire circumference. As a result, the annular member 540, like the annular member 530 of the first embodiment, closes the gap between the inner surface 521 and the outer surface 512, blocking a path through which discharge can occur. The annular member 540 corresponds to the "discharge prevention member" of this embodiment. Even in this aspect, the same effects as those described in the first embodiment can be achieved.

[0062] In this embodiment, by fixing the annular member 540 to the end portion 522 of the second insulating member 520 in advance, there is also an advantage that reassembly after disassembly is facilitated.

[0063] The 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.

[0064] FIG. 5 illustrates the configuration of the power supply member 400 and its surrounding area according to this embodiment, from the same perspective as FIG. 2 . In this embodiment, the annular member 530 is disposed in the gap between the end 513 of the first insulating member 510 and the surface 524 of the second insulating member 520, and is sandwiched and compressed between them. As in the first embodiment, the annular member 530 closes the gap between the first insulating member 510 and the second insulating member 520 (specifically, the gap between the inner surface 521 and the outer surface 512), blocking a path through which discharge could occur. To reliably prevent discharge, the annular member 530 preferably abuts against the outer surface 512 of the first insulating member 510 over the entire circumference. A portion of the compressed and deformed annular member 530 may be inserted into the gap between the inner surface 521 and the outer surface 512. This configuration also achieves the same effects as those described in the first embodiment.

[0065] The fourth 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. 6 illustrates the configuration of the power supply member 400 according to this embodiment and its surrounding area, viewed from the same perspective as Fig. 2. In this embodiment, the annular member 540 described in the second embodiment (Fig. 4) is fixed in advance to the end 513 of the first insulating member 510, rather than to the end 522 of the second insulating member 520.

[0067] The annular member 540 of this embodiment is a member that is fixed to the tip (end 513) of the first insulating member 510 before the first insulating member 510 is placed inside the through-hole 230. The annular member 540 is attached to the entire surface of the end 513, and therefore has an annular shape. Materials such as silicone rubber and fluorine-based polymers can be used as materials for the annular member 540. The annular member 540 may be fixed to the end 513 by adhesive or the like, or may be formed by applying a rubber coating to the end 513, for example.

[0068] When the first insulating member 510 and the second insulating member 520 are inserted into the through-hole 230, the annular member 540 is sandwiched and compressed between the end 513 of the first insulating member 510 and the surface 524 of the second insulating member 520. At this time, the deformed annular member 540 comes into contact with the outer surface 512 of the first insulating member 510 over the entire circumference. As a result, the annular member 540, like the annular member 530 of the first embodiment, closes the gap between the inner surface 521 and the outer surface 512, blocking a path through which discharge can occur. The annular member 540 corresponds to the "discharge prevention member" in this embodiment. Even in this aspect, the same effects as those described in the first embodiment can be achieved.

[0069] In this embodiment, by fixing the annular member 540 to the end portion 513 of the first insulating member 510 in advance, there is also an advantage that reassembly after disassembly becomes easier.

[0070] The fifth 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.

[0071] FIG. 7 illustrates the configuration of the power supply member 400 and its surrounding area according to this embodiment, from the same perspective as FIG. 2 . In this embodiment, an insulating cover 550 is provided instead of the annular member 530. The insulating cover 550 is a sheet-like member provided to cover a portion of the outer surface 401 of the power supply member 400 from the outside over the entire circumference. The insulating cover 550 is made of an electrically insulating material. The insulating cover 550 is preferably provided to cover at least a portion of the outer surface 401 that faces the portion between the end 513 and the inner surface 523. In other words, the insulating cover 550 is preferably provided to cover at least a portion that could be a starting point for discharge, as shown in FIG. 3 .

[0072] The insulating cover 550 may be a rubber coating that covers the outer surface 401, or may be a heat-shrinkable tube. Alternatively, it may be a coating made of a material such as polyvinyl chloride, silicone rubber, or a fluoropolymer. The provision of the insulating cover 550 prevents discharge from occurring between the first insulating member 510 and the second insulating member 520. The insulating cover 550 corresponds to the "discharge prevention member" in this embodiment. Even in this embodiment, the same effects as those described in the first embodiment can be achieved.

[0073] 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]

[0074] 10: Electrostatic chuck 100: Dielectric substrate 110: Face 140: Internal electrode 200: Base plate 230:Through hole 400: Power supply member 500: Insulating material 510: First insulating member 520: Second insulating member 530, 540: Annular member 550: Insulation cover 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, which is a metal member supporting the dielectric substrate and has a through hole formed therein; a power supply member for supplying power to the internal electrode, the power supply member being inserted into the through hole; an insulating member disposed between the inner surface of the through hole and the power supply member, The insulating member is a cylindrical first insulating member; a cylindrical second insulating member that covers a part of the first insulating member from an outer circumferential side, the first insulating member and the second insulating member cover the inner surface of the through hole from one end to the other end of the through hole, an electrostatic chuck further comprising a discharge prevention member for preventing discharge along a path from the power supply member, passing between the first insulating member and the second insulating member, to an inner surface of the through hole;

2. 2. The electrostatic chuck according to claim 1, wherein the discharge prevention member is an electrically insulating member covering an outer surface of the power supply member.

3. 2. The electrostatic chuck according to claim 1, wherein the discharge prevention member is an electrically insulating member provided so as to fill a gap between the first insulating member and the second insulating member.

4. 4. The electrostatic chuck according to claim 3, wherein the discharge prevention member is an elastic member.

5. 5. The electrostatic chuck according to claim 4, wherein the discharge prevention member is sandwiched and compressed between the tip of the second insulating member and the base plate.

6. 6. The electrostatic chuck according to claim 5, wherein the discharge prevention member is fixed to a tip of the second insulating member in advance.

7. 5. The electrostatic chuck according to claim 4, wherein the discharge prevention member is sandwiched and compressed between the tip of the first insulating member and the second insulating member.

8. 8. The electrostatic chuck according to claim 7, wherein the discharge prevention member is fixed to the tip of the first insulating member in advance.

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