Electrostatic chuck

Abstract

To provide an electrostatic chuck capable of suppressing dielectric breakdown through a gas hole.SOLUTION: An electrostatic chuck 10 includes a dielectric substrate 100 in which a gas hole 160 is formed, a base plate 200 which is a metal member supporting the dielectric substrate 100 and in which a gas hole 260 is formed at a position corresponding to the gas hole 160, and a bonding layer 300 which bonds the dielectric substrate 100 and the base plate 200. A protruding portion 140 that protrudes toward the base plate 200 is formed on a surface 120 of the dielectric substrate 100 on the side of the base plate 200. The gas hole 160 is formed so as to penetrate the protruding portion 140.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] For example, in semiconductor manufacturing equipment such as an etching device, an electrostatic chuck is provided 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 for 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 inert gas such as helium is supplied to the space between the dielectric substrate and the substrate for the purpose of adjusting the temperature of the substrate during processing, etc. For example, as described in Patent Document 1 below, the inert gas is supplied to the space through gas holes formed in each of the base plate and the dielectric substrate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-109806 A Summary of the Invention [Problem to be solved by the invention]

[0005] During substrate processing, the potential of the substrate and its surroundings increases due to the incidence of plasma and the application of voltage to the chucking electrode. Meanwhile, the potential of the base plate is maintained at the same potential (e.g., ground potential) as the surrounding components that make up the semiconductor manufacturing equipment. For this reason, dielectric breakdown is more likely to occur along the path through the gas holes.

[0006] In the vicinity of the gas hole, where the dielectric substrate and the base plate face each other, a space having a thickness approximately equal to that of the bonding layer is formed between the two members. The thickness is, for example, about 250 μm. According to Paschen's law, the pressure of the inert gas inside the gas hole is often in a pressure range where dielectric breakdown is relatively likely to occur in the space of the above thickness.

[0007] The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrostatic chuck that can suppress dielectric breakdown through gas holes. [Means for solving the problem]

[0008] In order to solve the above problems, the electrostatic chuck according to the present invention includes a dielectric substrate having a mounting surface on which an object to be attracted is placed and in which a first gas hole is formed, a base plate which is a metal member supporting the dielectric substrate and in which a second gas hole is formed at a position corresponding to the first gas hole, and a bonding layer bonding the dielectric substrate and the base plate. A protrusion protruding toward the base plate is formed on the surface of the dielectric substrate facing the base plate. The first gas hole is formed to penetrate the protrusion.

[0009] In the electrostatic chuck having such a configuration, since the protrusion is formed on the dielectric substrate, the distance between the dielectric substrate and the base plate, which face each other at the position of the first gas hole, etc., can be made smaller than the thickness of the bonding layer. By making the distance between the dielectric substrate and the base plate small enough to prevent dielectric breakdown, it is possible to sufficiently suppress dielectric breakdown between the two members. Effect of the Invention

[0010] According to the present invention, it is possible to provide an electrostatic chuck capable of suppressing dielectric breakdown through gas holes. [Brief description of the drawings]

[0011] [Figure 1]1 is a cross-sectional view illustrating a schematic configuration of an electrostatic chuck according to a first embodiment. [Diagram 2] 2 is an enlarged view showing in detail a portion of the electrostatic chuck shown in FIG. 1; FIG. [Diagram 3] FIG. 11 is a cross-sectional view showing a configuration of an electrostatic chuck according to a modified example. [Figure 4] FIG. 11 is an enlarged view showing a partial configuration of an electrostatic chuck according to a second embodiment. [Diagram 5] FIG. 11 is an enlarged view showing a partial configuration of an electrostatic chuck according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components in each drawing are denoted by the same reference numerals as much as possible, and duplicated description 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 substrate W to be attracted is, for example, a silicon wafer. The electrostatic chuck 10 may be used in an apparatus other than a semiconductor manufacturing apparatus.

[0014] 1 shows, in a schematic cross-sectional view, the configuration of an electrostatic chuck 10 in a state in which the electrostatic chuck 10 attracts and holds a substrate W. The electrostatic chuck 10 includes a dielectric substrate 100, a base plate 200, and a bonding layer 300.

[0015] The dielectric substrate 100 is a substantially disk-shaped member made of a sintered ceramic body. The dielectric substrate 100 is made of, for example, high-purity aluminum oxide (Al 2 O 3 ), but may 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, etc. required for the dielectric substrate 100 in the 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 "joined surface" that is joined to the base plate 200 via a joining 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 be referred to as a "top view".

[0017] An adsorption electrode 130 is embedded inside the dielectric substrate 100. The adsorption electrode 130 is a thin flat layer made of a metal material such as tungsten, and is arranged parallel to the surface 110. The material of the adsorption electrode 130 may be molybdenum, platinum, palladium, or the like, in addition to tungsten. 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, thereby adsorbing and holding the substrate W. As the configuration of the power supply path, various known configurations can be adopted. The adsorption electrode 130 may be provided as a so-called "monopolar" electrode as in this embodiment, or may be provided as two so-called "bipolar" electrodes.

[0018] 1, a space SP1 is formed between the dielectric substrate 100 and the substrate W. When a process such as etching is performed in the semiconductor manufacturing apparatus, helium gas for temperature adjustment is supplied from the outside to the space SP1 through a gas hole 160. By providing helium gas between the dielectric substrate 100 and the substrate W, the thermal resistance between them is adjusted, and the temperature of the substrate W is thereby maintained at an appropriate temperature. The gas for temperature adjustment supplied to the space SP1 may be a type of gas other than helium.

[0019] The gas holes 160 are formed to extend vertically from the bottom surface 116 toward the surface 120, which will be described later. The gas holes 160 may be formed to extend linearly as in this embodiment, but may be formed to bend midway from the bottom surface 116 toward the surface 120. In this embodiment, a pair of gas holes 160 formed in positions close to each other are formed in multiple sets so as to penetrate each part of the dielectric substrate 100. In FIG. 1, only one set of gas holes 160 is shown. The gas holes 160 correspond to the "first gas holes" in this embodiment. The specific configuration of the gas holes 160 and the surrounding area will be described later.

[0020] A seal ring 111 and dots 112 are provided on a surface 110 which is a mounting surface, and the above-mentioned space SP1 is formed around these.

[0021] The seal ring 111 is a wall that divides the space SP1 at the outermost position. The upper end of the seal ring 111 forms part of the surface 110 and abuts against the substrate W. A plurality of seal rings 111 may be provided to divide the space SP1. With this configuration, it is possible to individually adjust the pressure of the helium gas in each space SP1 and make the surface temperature distribution of the substrate W during processing more uniform. In this case, gas holes 160 are formed at positions corresponding to each of the plurality of spaces SP1.

[0022] 1, the portion marked with the reference symbol "116" is the bottom surface of the space SP1. 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 as a result of digging down a part of the surface 110 to the position of the bottom surface 116.

[0023] The dots 112 are circular protrusions protruding 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 abuts against the substrate W. By providing a plurality of such dots 112, bending of the substrate W is suppressed.

[0024] 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 upper surface 210 of the base plate 200 in FIG. 1 is a "bonded surface" that is bonded to the dielectric substrate 100 via a bonding layer 300.

[0025] The bonding layer 300 is a layer provided between the dielectric substrate 100 and the base plate 200, and bonds the two 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 any 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 that the thermal resistance between the dielectric substrate 100 and the base plate 200 is small.

[0026] 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 the insulating film, the dielectric strength of the base plate 200 can be increased.

[0027] 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 apparatus, 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 SP1, the dielectric substrate 100, and the base plate 200, and is discharged to the outside together with the coolant.

[0028] A gas hole 260 is formed in the base plate 200. The gas hole 260 is a hole that communicates with the gas hole 160 described above, and forms part of a path for supplying helium gas toward the space SP1.

[0029] Gas hole 260 is formed to extend vertically from surface 210 toward surface 220, which is the opposite side to surface 210. A plurality of gas holes 260 are formed, one at a position corresponding to each of the pairs of gas holes 160. In other words, two gas holes 160 are connected to one gas hole 260. Gas hole 260 corresponds to the "second gas hole" in this embodiment.

[0030] Gas hole 260 may be formed to extend linearly as in this embodiment, or may be formed to bend midway from surface 210 to surface 220. In either case, it is sufficient that the opening of gas hole 160 at the end on the surface 120 side and the opening of gas hole 260 at the end on the surface 210 side overlap each other in a top view.

[0031] 1, the portion of the gas hole 260 near the end on the surface 210 side is an expanded diameter portion 261 that is larger in diameter than the remaining portion. A ventilation member 270 is disposed inside the expanded diameter portion 261. The ventilation member 270 is a member made of alumina, for example, and a part of it (a porous portion 271 described below) has air permeability. By disposing such a ventilation member 270 inside the gas hole 260, the flow of helium gas in the gas hole 260 is ensured, while the occurrence of dielectric breakdown in the path through the gas hole 260 is suppressed.

[0032] The ventilation member 270 is a substantially cylindrical member, and is disposed inside the expanded diameter portion 261 with its central axis coinciding with the central axis of the expanded diameter portion 261. The outer diameter of the ventilation member 270 is substantially equal to the inner diameter of the expanded diameter portion 261. The ventilation member 270 is, for example, press-fitted into the expanded diameter portion 261. The end face of the ventilation member 270 on the dielectric substrate 100 side is in the same plane as the surface 210.

[0033] The ventilation member 270 has a porous portion 271 and a dense portion 272, which are integrated together.

[0034] The porous portion 271 is a portion formed of porous ceramic having air permeability. Helium gas supplied to the space SP1 passes through the porous portion 271 of the ventilation member 270. The porosity of the porous portion 271 is appropriately set according to the balance between the air permeability required for gas supply to the space SP1 and the necessary dielectric strength voltage. The porous portion 271 is cylindrical, and its central axis coincides with the central axis of the entire ventilation member 270.

[0035] The dense portion 272 is a portion formed of dense ceramic that does not have gas permeability. In other words, the dense portion 272 is a portion of the ventilation member 270 through which helium gas does not pass. The ceramic material (alumina in this embodiment) constituting the dense portion 272 is the same as the ceramic material constituting the porous portion 271. Alternatively, the two may be formed of different materials.

[0036] The dense portion 272 has a cylindrical shape, and its central axis coincides with the central axis of the entire ventilation member 270. The above-mentioned porous portion 271 is housed inside the dense portion 272. The dimension of the dense portion 272 in the vertical direction in Fig. 1 is the same as the dimension of the porous portion 271 in the same direction. The porous portion 271 and the dense portion 272 may be formed by joining separate separable members together, or may be formed from the beginning as a single unit by sintering.

[0037] 2 shows an enlarged view of the gas hole 160 and the structure of the surrounding area. Note that in this drawing, the dots 112 and the like formed on the surface 110 are omitted.

[0038] 2, a protrusion 140 is formed on a surface 120 of the dielectric substrate 100 facing the base plate 200. In the protrusion 140, a part of the surface 120 protrudes toward the base plate 200. The shape of the protrusion 140 in a top view is circular. A pair of gas holes 160 formed at positions close to each other are both formed to penetrate one of the protrusions 140.

[0039] The protrusion 140 is integrated with other parts (parts other than the protrusion 140) of the dielectric substrate 100. Such a protrusion 140 can be formed, for example, by subjecting the surface 120 of the dielectric substrate 100 to processing such as sandblasting.

[0040] The central axis of the protruding portion 140 coincides with the central axis of the entire ventilation member 270. The outer diameter of the protruding portion 140 is approximately equal to the outer diameter of the porous portion 271.

[0041] Between the dielectric substrate 100 and the ventilation member 270, an annular seal member 310 is disposed. The seal member 310 is a member formed by, for example, curing a silicone adhesive. The inner diameter of the seal member 310 is approximately equal to the outer diameter of the protruding portion 140. The thickness of the seal member 310 (the dimension along the direction perpendicular to the mounting surface) is equal to the thickness of the bonding layer 300. The seal member 310 is disposed so as to surround the entire periphery of the protruding portion 140 from the outer periphery side. The seal member 310 is a member disposed to prevent uncured adhesive that will become the bonding layer 300 from entering inside during the manufacture of the electrostatic chuck 10. The seal member 310 may be a member made of the same material as the bonding layer 300, or may be a member made of a different material.

[0042] The amount of protrusion of the protrusion 140 toward the base plate 200 is slightly smaller than the thickness of the bonding layer 300. Therefore, a space SP2, which is a minute gap, is formed between the tip surface of the protrusion 140 and the ventilation member 270.

[0043] As described above, in the electrostatic chuck 10 of the present embodiment, the protruding portion 140 is formed on the dielectric substrate 100, and the gas holes 160 are formed so as to penetrate the protruding portion 140.

[0044] The reason for adopting such a configuration will be described. During processing of the substrate W, the potential of the substrate W and its surroundings increases due to the incidence of plasma and the application of a voltage to the chucking electrode 130. Meanwhile, the potential of the base plate 200 is maintained at the same potential (e.g., ground potential) as the peripheral members constituting the semiconductor manufacturing apparatus. For this reason, dielectric breakdown is likely to occur in the path through the gas holes 160 and the gas holes 260.

[0045] If the protruding portion 140 is not formed on the dielectric substrate 100, the thickness of the space SP2 is equal to the thickness of the bonding layer 300. That is, in the vicinity of the gas holes 160 etc., and in the portion where the dielectric substrate 100 and the base plate 200 face each other, a space SP2 having a thickness approximately equal to the thickness of the bonding layer 300 is formed between the two members. The thickness is, for example, about 250 μm. According to Paschen's law, the pressure of the helium gas inside the gas holes 160 etc. is often in a pressure range where dielectric breakdown is relatively likely to occur in the space of the above thickness.

[0046] Therefore, in this embodiment, the protrusion 140 is formed on the dielectric substrate 100 to make the thickness of the space SP2 smaller than the thickness of the bonding layer 300. That is, the distance between the dielectric substrate 100 and the base plate 200 (the ventilation member 270 in this embodiment), which face each other at the position of the gas hole 160 or the like, is made smaller than the thickness of the bonding layer 300. By making the distance between the two members small enough to prevent dielectric breakdown, it is possible to sufficiently suppress dielectric breakdown via the gas hole 160 and the space SP2.

[0047] As a configuration for narrowing the space SP2, instead of forming the protruding portion 140, it is also possible to reduce the overall thickness of the bonding layer 300. However, if the thickness of the bonding layer 300 is changed, there is a concern that the bonding layer 300 may not be able to absorb the thermal expansion difference between the dielectric substrate 100 and the base plate 200. Therefore, as in this embodiment, a configuration in which the protruding portion 140 is formed without changing the thickness of the bonding layer 300 is preferable.

[0048] There may be an embodiment in which the ventilation member 270 is not disposed inside the gas hole 260, and the protrusion 140 and the base plate 200 directly face each other. Even in this embodiment, dielectric breakdown can be prevented by narrowing the space SP2 by forming the protrusion 140. However, in order to make dielectric breakdown less likely to occur, it is preferable to dispose the ventilation member 270 as in this embodiment.

[0049] The entire ventilation member 270 may be made of the porous portion 271. However, when the dense portion 272 is provided on the outer periphery of the porous portion 271 as in the present embodiment, the inner surface (i.e., metal) of the gas hole 260 is covered with the dense portion 272, so that it is possible to more reliably prevent the occurrence of dielectric breakdown.

[0050] As described above, the outer diameter of the protruding portion 140 is approximately equal to the outer diameter of the porous portion 271. As a result, the porous portion 271 overlaps with each of the gas holes 160 formed in the protruding portion 140 in a top view. Since the porous portion 271 is disposed directly below the gas holes 160, the supply of helium gas toward the space SP1 is not hindered more than necessary.

[0051] The dense portion 272 is located entirely outside the protruding portion 140 in top view. In this configuration, the seal member 310 surrounding the protruding portion 140 from the outer periphery can be brought into contact with the dense portion 272 over the entire circumference. This makes it possible to prevent the uncured adhesive that will become the bonding layer 300 from penetrating into the porous portion 271. Note that only a part of the dense portion 272, rather than the entire dense portion 272, may be located outside the protruding portion 140 in top view. In other words, the inner diameter of the dense portion 272 may be slightly smaller than the outer diameter of the protruding portion 140.

[0052] 2, the portion of the gas hole 160 near the end on the base plate 200 side is an expanded diameter portion 161 that is expanded in diameter compared to the other portions. That is, the inner diameter of the end of the gas hole 160 on the base plate 200 side is larger than the inner diameter of the end of the gas hole 160 on the mounting surface side. By expanding the inner diameter of the inlet portion of the gas hole 160 for helium gas, the flow rate of the helium gas flowing into the gas hole 160 can be ensured even when the thickness of the space SP2 is very narrow. The length of the expanded diameter portion 161 is preferably approximately the same as the thickness of the bonding layer 300, for example.

[0053] The protruding portion 140 may be formed, for example, by joining another disk-shaped member to the surface 120 of the dielectric substrate 100. However, in consideration of the possibility of the protruding portion 140 falling off, it is preferable that the protruding portion 140 is formed integrally with the other portion of the dielectric substrate 100, as in this embodiment. In either case, the protruding portion 140 is preferably formed as a dense body having no air permeability, like the other portion of the dielectric substrate 100.

[0054] The number of gas holes 160 penetrating one protruding portion 140 may be only one, or may be three or more. By forming a plurality of gas holes 160 in one protruding portion 140 as in this embodiment, it is possible to make each gas hole 160 small in diameter while ensuring a sufficient flow rate of helium gas. As a result, it is possible to further suppress the occurrence of dielectric breakdown.

[0055] The outer circumferential edge of the tip surface of the protrusion 140 may be chamfered 141 to prevent chipping, etc. The chamfer 141 may be, for example, an R chamfer as shown in Fig. 3(A) or a C chamfer as shown in Fig. 3(B).

[0056] A second embodiment will be described below. In the following, differences from the first embodiment will be mainly described, and descriptions of the same points as the first embodiment will be omitted as appropriate.

[0057] Fig. 4 illustrates the configuration of the electrostatic chuck 10 according to this embodiment from the same perspective as Fig. 2. As shown in Fig. 4, the ventilation member 270 of this embodiment extends to a position closer to the dielectric substrate 100 side than in the first embodiment shown in Fig. 2.

[0058] For ease of explanation, the surface of the base plate 200 that faces the dielectric substrate 100 via the bonding layer 300 is also referred to as the "facing surface" below. In this embodiment, the surface 210 corresponds to the "facing surface". Hereinafter, the surface 210 is also referred to as the "facing surface 210".

[0059] Even if the surface of the base plate 200 including the surface 210 is covered with an insulating film, the surface 210, not the surface of the insulating film, corresponds to the "opposing surface" as described above. In either case, the "opposing surface" refers to the surface of the metal base plate 200 that faces the dielectric substrate 100 via the bonding layer 300.

[0060] 4, a part of the ventilation member 270 in this embodiment protrudes from the opposing surface 210 toward the dielectric substrate 100. That is, the protruding portion 140 protrudes from the dielectric substrate 100 toward the space SP2, while the ventilation member 270 protrudes from the base plate 200 toward the space SP2. The amount of protrusion of the ventilation member 270 toward the dielectric substrate 100 is smaller than the thickness of the bonding layer 300.

[0061] In this manner, by having both the protruding portion 140 and the ventilation member 270, which face each other, protrude toward the space SP2, the thickness of the space SP2 is further reduced, making it even more difficult for dielectric breakdown to occur through the space SP2.

[0062] Other configurations will be described. A chamfered portion 211 is formed at the boundary between the inner surface of the expanded diameter portion 261 of the gas hole 260 and the opposing surface 210. The chamfered portion 211 is an inclined surface such that the inner diameter becomes larger toward the dielectric substrate 100. A part of the bonding layer 300 also penetrates between the chamfered portion 211 and the dense portion 272.

[0063] The tip surface of ventilation member 270 on the dielectric substrate 100 side is hereinafter also referred to as "tip surface 273." A chamfered portion 274 is formed on the outer peripheral portion of tip surface 273, i.e., the boundary portion between the outer surface of dense portion 272 and tip surface 273. Chamfered portion 274 is an inclined surface whose diameter becomes smaller toward the dielectric substrate 100 side. Chamfered portion 274 may be a C-chamfer or an R-chamfer.

[0064] In this embodiment, an annular seal member 310 is disposed between the ventilation member 270 and the dielectric substrate 100 so as to surround the protruding portion 140 from the outside. The seal member 310 in this embodiment is mostly sandwiched between the tip surface 273 and the surface 120. Therefore, the thickness of the seal member 310 (the dimension along the direction perpendicular to the mounting surface) is smaller than the thickness of the bonding layer 300. By disposing such a seal member 310, the bonding layer 300 is prevented from penetrating toward the inside of the seal member 310. That is, a situation in which the uncured adhesive that becomes the bonding layer 300 penetrates during manufacturing and blocks the gas hole 160, etc. is prevented.

[0065] 4, the outer circumferential end of the seal member 310 extends to a position directly above the chamfered portion 274. In other words, the seal member 310 is disposed so as to straddle both the tip surface 273 and the chamfered portion 274 in a top view.

[0066] If the sealing member 310 overlaps only with the tip surface 273 in a top view, the entire sealing member 310 is compressed by the tip surface 273 when the electrostatic chuck 10 is assembled. As a result, the force applied from the sealing member 310 to the dielectric substrate 100 becomes too large, and the dielectric substrate 100 may be damaged.

[0067] Therefore, in this embodiment, as described above, the seal member 310 in top view is configured to span both the tip surface 273 and the chamfered portion 274. In such a configuration, there is room for a part of the seal member 310 compressed during assembly to escape to the relatively large space directly above the chamfered portion 274. Since the force received by the dielectric substrate 100 is smaller than when the entire seal member 310 is compressed by the tip surface 273, damage to the dielectric substrate 100 can be suppressed.

[0068] A third embodiment will be described below. In the following, differences from the above-described second embodiment will be mainly described, and descriptions of the same points as the second embodiment will be omitted as appropriate.

[0069] 5 illustrates the configuration of the electrostatic chuck 10 according to this embodiment from the same perspective as in FIG. 2 and FIG. 4. As shown in FIG. 5, in this embodiment, the surface of the base plate 200 is covered with an insulating film 230. The insulating film 230 is a film made of an insulating material such as alumina, and is formed by, for example, thermal spraying. The insulating film 230 in this embodiment is formed so as to cover the opposing surface 210 and the chamfered portion 211. The range of the base plate 200 covered by the insulating film 230 may be different from the above range.

[0070] The ventilation member 270 of the present embodiment is disposed so that a part of it protrudes from the surface of the insulating film 230 toward the dielectric substrate 100. By disposing the ventilation member 270 so that it protrudes not only from the opposing surface 210 but also from the surface of the insulating film 230, the thickness of the space SP2 can be further reduced.

[0071] Depending on the thickness of the insulating film 230 and the bonding layer 300, the ventilation member 270 may protrude from the facing surface 210 but may not protrude from the surface of the insulating film 230.

[0072] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Any design modifications made by a person skilled in the art to these specific examples are also included within the scope of the present disclosure as long as they have the features of the present disclosure. The elements of each of the above-mentioned specific examples and their arrangements, conditions, shapes, etc. are not limited to those exemplified and can be changed as appropriate. The combination of each of the elements of each of the above-mentioned specific examples can be changed as appropriate as long as no technical contradiction occurs. [Explanation of symbols]

[0073] 10: Electrostatic chuck 100: Dielectric substrate 110,120,210: Surface 140:Protrusion 141: Chamfering 160: Gas hole 200: Base plate 230: Insulating film 260: Gas hole 270: Ventilation material 271: Porous part 272: Dense part 273: Tip surface 274: Chamfered part 310: Sealing material

Claims

1. a dielectric substrate having a mounting surface on which an object to be attracted is placed and in which a first gas hole is formed; a base plate which is a metal member supporting the dielectric substrate and has second gas holes formed at positions corresponding to the first gas holes; a bonding layer that bonds the dielectric substrate and the base plate, a protrusion protruding toward the base plate is formed on a surface of the dielectric substrate facing the base plate, The electrostatic chuck is characterized in that the first gas hole is formed so as to penetrate the protrusion.

2. 2. The electrostatic chuck according to claim 1, wherein a ventilation member is disposed inside the second gas hole.

3. The ventilation member has a porous portion that is a portion having air permeability, a dense portion that is an air-impermeable portion and surrounds the porous portion from an outer periphery side; 3. The electrostatic chuck according to claim 2, wherein the porous portion overlaps with the first gas hole when viewed from a direction perpendicular to the mounting surface.

4. When viewed from a direction perpendicular to the placement surface, The electrostatic chuck according to claim 3 , wherein at least a portion of the dense portion is located outside the protruding portion.

5. 2. The electrostatic chuck according to claim 1, wherein a plurality of the first gas holes are formed so as to penetrate one of the protrusions.

6. 2 . The electrostatic chuck according to claim 1 , wherein an inner diameter of the first gas hole at an end portion on the base plate side is larger than an inner diameter of the first gas hole at an end portion on the mounting surface side.

7. 2. The electrostatic chuck according to claim 1, wherein the protrusion is integral with another portion of the dielectric substrate.

8. 2. The electrostatic chuck according to claim 1, wherein a tip of said protrusion is chamfered.

9. When the surface of the base plate facing the dielectric substrate via the bonding layer is defined as an opposing surface, 3. The electrostatic chuck according to claim 2, wherein a portion of the ventilation member protrudes from the opposing surface toward the dielectric substrate.

10. The facing surface is covered with an insulating film, 10. The electrostatic chuck according to claim 9, wherein a portion of the ventilation member protrudes from a surface of the insulating film toward the dielectric substrate.

11. an annular seal member is disposed between the ventilation member and the dielectric substrate; 10. The electrostatic chuck according to claim 9, wherein the bonding layer is prevented from penetrating toward the inside of the seal member.

12. The ventilation member is a tip surface on the dielectric substrate side; A chamfered portion is formed on the outer circumferential side of the tip surface, When viewed from a direction perpendicular to the placement surface, The electrostatic chuck according to claim 11, wherein the seal member is disposed so as to span both the tip surface and the chamfered portion.

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