Electrostatic chuck

Abstract

To provide an electrostatic chuck capable of suppressing the occurrence of discharge through gas holes.SOLUTION: An electrostatic chuck 10 includes a first portion 101 including a surface 110 on which a substrate W is placed, and a second portion 102 protruding further outward from the outer peripheral edge of the first portion 101 and being thinner than the first portion 101. A first gas hole 150 is formed in the first portion 101. A first vent member 400 having air permeability is disposed inside the first gas hole 150. A second gas hole 160 is formed in the second portion 102. A second vent member 500 having air permeability is disposed inside the second gas hole 160. The height dimension of the second vent member 500 is smaller than the height dimension of the first vent member 400.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 etching equipment is equipped 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 on which an attracting electrode is provided. When a voltage is applied to the attracting electrode, an electrostatic force is generated, attracting and holding the substrate placed on the dielectric substrate.

[0003] During substrate processing, an annular member called a focus ring or the like is arranged around the substrate. For example, as described in Patent Document 1 below, a dielectric substrate may be provided with a flange portion on which such an annular member is placed. The portion of the dielectric substrate on which a substrate to be processed, such as a silicon wafer, is placed is hereinafter also referred to as the "first portion." The flange portion provided on the dielectric substrate is hereinafter also referred to as the "second portion." The second portion (flange portion) protrudes further outward from the outer circumferential edge of the first portion and is thinner than the first portion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-281680 Summary of the Invention [Problem to be solved by the invention]

[0005] A gas hole is formed in the first portion of the dielectric substrate. The gas hole is a through-hole for supplying an inert gas to the space between the mounting surface and the substrate. By supplying the inert gas at a predetermined pressure to the space, heat transfer between the substrate and the dielectric substrate is adjusted. This makes it possible to maintain the temperature of the substrate at an appropriate temperature during processing such as etching.

[0006] In order to prevent discharge through the gas hole, a breathable member made of an insulator such as alumina is placed inside the gas hole.

[0007] The inventors have been studying the possibility of forming gas holes not only in the first portion but also in the second portion to adjust the temperature of the annular member surrounding the substrate. In this case, it is preferable to dispose an air-permeable member inside the gas holes in the second portion, just like the gas holes in the first portion. However, no specific study has been conducted to date on what kind of air-permeable member should be disposed in each of the first and second portions, which have different thicknesses.

[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 suppress the occurrence of discharge through gas holes. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides an electrostatic chuck comprising: a first portion including a mounting surface on which an object to be attracted is placed; and a second portion protruding from the outer circumferential edge of the first portion toward the outer periphery and thinner than the first portion. A first gas hole is formed in the first portion, and a first vent member having gas permeability is disposed inside the first gas hole. A second gas hole is formed in the second portion, and a second vent member having gas permeability is disposed inside the second gas hole. When the dimension perpendicular to the mounting surface is defined as the height dimension, in this electrostatic chuck, the height dimension of the second vent member is smaller than the height dimension of the first vent member.

[0010] In the electrostatic chuck having the above configuration, a vent member having an appropriate height corresponding to the length of each of the first gas holes formed in the first portion and the second gas holes formed in the second portion can be disposed inside each of the first gas holes. For example, by disposing the first vent member so as to occupy substantially the entire first gas hole and disposing the second vent member so as to occupy substantially the entire second gas hole, it becomes possible to sufficiently suppress the occurrence of discharge through each gas hole. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an electrostatic chuck that can suppress the occurrence of discharge through gas holes. [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] 1 is a cross-sectional view schematically illustrating the configuration of a ventilation member according to a first embodiment. [Figure 3] 1A and 1B are diagrams schematically illustrating the configuration of a ventilation member according to a first embodiment. [Figure 4] FIG. 6 is a cross-sectional view schematically showing the configuration of a ventilation member according to a second embodiment. [Figure 5] 10A and 10B are diagrams schematically illustrating the configuration of a ventilation member according to a third embodiment. [Figure 6] FIG. 10 is a cross-sectional view schematically showing the configuration of a ventilation member according to a fourth embodiment. [Figure 7] FIG. 10 is a cross-sectional view schematically showing the configuration of a ventilation member 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 object to be attracted, that is, the substrate W, is, for example, a silicon wafer. The electrostatic chuck 10 may also be used in apparatuses other than semiconductor manufacturing apparatuses.

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

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

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

[0018] The dielectric substrate 100 has a first portion 101 and a second portion 102. The first portion 101 is a generally cylindrical portion that extends from a surface 110 downward in Fig. 1 to a surface 120. Such a first portion 101 can be said to be a portion of the dielectric substrate 100 that includes the surface 110, which is the mounting surface.

[0019] The second portion 102 is an annular portion that protrudes further outward from the outer peripheral edge of the first portion 101, and is also referred to as the "flange" of the dielectric substrate 100. In FIG. 1, the boundary between the first portion 101 and the second portion 102 is indicated by a dotted line DL. The second portion 102 is thinner than the first portion 101. That is, the dimension of the second portion 102 in a direction perpendicular to the surface 110 (the up-down direction in FIG. 1) is smaller than the dimension of the first portion 101 in the same direction. The surface 120 mentioned above is the lowermost surface of the first portion 101 in FIG. 1 and is also the lowermost surface of the second portion 102. The uppermost surface 180 of the second portion 102 is located lower than the surface 110 in FIG. 1.

[0020] When a substrate W is processed in a semiconductor manufacturing apparatus, an annular member RE, such as a focus ring, is arranged around the substrate W. A surface 180 of the second portion 102 supports the annular member RE from below. The surface 180 is parallel to the surface 110. The surface 180 may support the entire annular member RE from below, as in the example of FIG. 1, or may support only a portion of the annular member RE.

[0021] An attraction electrode 130 is provided inside the first portion 101 of 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 molybdenum, platinum, palladium, or the like, in addition to tungsten. When a voltage is applied to the attraction electrode 130 from the outside via a power supply path (not shown), an electrostatic force is generated between the surface 110 and the substrate W, thereby attracting and holding the substrate W. The power supply path may be configured in any of various well-known ways. The attraction electrode 130 may be provided as a single so-called "monopolar" electrode as in this embodiment, or as two so-called "bipolar" electrodes.

[0022] An internal electrode 140 is provided inside the second portion 102 of the dielectric substrate 100. The internal electrode 140 is a thin, flat layer made of the same material as the chucking electrode 130 and is disposed parallel to the surface 180. When a voltage is applied to the internal electrode 140 from the outside via a power supply line (not shown), an electrostatic force is generated between the surface 180 and the annular member RE, thereby attracting and holding the annular member RE. Various known configurations can be used as the configuration of the power supply line connected to the internal electrode 140. Only one internal electrode 140 may be provided as a so-called "monopolar" electrode as in this embodiment, or two internal electrodes 140 may be provided as so-called "bipolar" electrodes.

[0023] In addition to the above-described chucking electrode 130 and internal electrode 140, an RF electrode for generating plasma and attracting it toward the substrate W may be provided inside the dielectric substrate 100. The chucking electrode 130 and internal electrode 140 may also be used as the above-described RF electrode.

[0024] 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, helium gas for temperature adjustment is supplied to the space SP from the outside through a first gas hole 150 described below. 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] A first gas hole 150 is formed in the first portion 101 of the dielectric substrate 100. The first gas hole 150 is a circular through-hole formed to extend in a direction perpendicular to the surface 110, which is the mounting surface. The end of the first gas hole 150 on the surface 110 side is connected to the space SP. The first gas hole 150 is part of a flow path for supplying helium gas toward the space SP. A plurality of first gas holes 150 are formed in the first portion 101, but only one of them is shown in FIG. 1.

[0030] The portion of the first gas hole 150 on the surface 120 side has a larger diameter than the portion on the surface 110 side. This larger diameter portion will be referred to as the "larger diameter portion 151" below. A first ventilation member 400 is disposed inside the large diameter portion 151. The first ventilation member 400 is a substantially cylindrical member made of an insulating material and has gas permeability, as will be described later. In this embodiment, alumina is used as the material for the first ventilation member 400. The first ventilation member 400 is provided to prevent discharge (dielectric breakdown) from the substrate W through the first gas hole 150 to the base plate 200. The specific configuration of the first ventilation member 400 will be described later.

[0031] Second gas holes 160 are formed in the second portion 102 of the dielectric substrate 100. The second gas holes 160 are circular through-holes extending in a direction perpendicular to the surface 110 and the surface 180. The ends of the second gas holes 160 on the surface 180 side are open at the surface 180. The second gas holes 160 are part of a flow path for supplying helium gas toward a gap (not shown) between the surface 180 and the annular member RE. By providing helium gas between the surface 180 and the annular member RE, the thermal resistance between them is adjusted, thereby maintaining the temperature of the annular member RE at an appropriate temperature. A plurality of second gas holes 160 are formed in the second portion 102, and are arranged in a ring shape when viewed from above, but only two of them are shown in FIG. 1 . The gas supplied through the second gas holes 160 may be a different type of gas from the gas supplied through the first gas holes 150.

[0032] The portion of the second gas hole 160 on the surface 120 side has a larger diameter than the portion on the surface 180 side. This larger diameter portion will be referred to as the "large diameter portion 161" below. A second ventilation member 500 is disposed inside the large diameter portion 161. The second ventilation member 500 is a substantially cylindrical member made of an insulating material and has air permeability, as will be described later. In this embodiment, alumina is used as the material for the second ventilation member 500. The second ventilation member 500 is provided to prevent discharge from reaching the base plate 200 through the second gas hole 160. The specific configuration of the second ventilation member 500 will be described later.

[0033] 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. The outer shape of the surface 210 in a top view is generally the same as the outer shape of the second portion 102 in a top view.

[0034] 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.

[0035] 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.

[0036] A coolant flow path 240 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 240 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 then discharged to the outside together with the coolant. The coolant is supplied to and discharged from the coolant flow path 240 through an opening (not shown) formed on the surface 220 of the base plate 200 opposite the surface 210. The coolant flow path 240 is formed to pass not only through the area overlapping with the first portion 101 in top view, but also through the area overlapping with the second portion 102. Therefore, not only the substrate W but also the annular member RE are cooled by the coolant passing through the coolant flow path 240.

[0037] Gas holes 251 are formed in the surface 210 of the base plate 200 at positions that overlap with the expanded diameter portions 151 in a top view. The shape of the gas holes 251 in a top view is the same circular shape as the shape of the expanded diameter portions 151 in a top view. The gas holes 251 are formed to extend from the surface 210 to a predetermined depth in a direction perpendicular to the surface 210.

[0038] An opening 301 is formed in the bonding layer 300 at a position between the expanded diameter portion 151 and the gas hole 251. An end of the gas hole 251 on the surface 210 side is connected to the expanded diameter portion 151 of the first gas hole 150 through the opening 301. An end of the gas hole 251 on the opposite side to the above end is connected to a distribution flow path 271 formed inside the base plate 200.

[0039] The distribution flow path 271 is a flow path formed to distribute helium gas supplied from the outside to each of the multiple gas holes 251. The distribution flow path 271 is routed along a path that passes directly below all of the gas holes 251. A configuration may be adopted in which multiple distribution flow paths 271 are formed and the supply of helium gas to the gas holes 251 is divided into multiple systems. With such a configuration, for example, the pressure of the helium gas supplied to the gas holes 251 on the central side and the pressure of the helium gas supplied to the gas holes 251 on the outer periphery side can be made different from each other.

[0040] An air-permeable member 610 is disposed inside the gas hole 251. The air-permeable member 610 is a substantially cylindrical member that is air-permeable. In this embodiment, porous alumina is used as the air-permeable member 610. The air-permeable member 610 may be a member in which a plurality of air holes extending linearly from one end to the other end are formed, or may be a member in which a mesh-like flow path is formed.

[0041] Gas holes 261 are formed in the surface 210 of the base plate 200 at positions that overlap with the expanded diameter portions 161 in a top view. The shape of the gas holes 261 in a top view is the same circular shape as the shape of the expanded diameter portions 161 in a top view. The gas holes 261 are formed to extend from the surface 210 to a predetermined depth in a direction perpendicular to the surface 210.

[0042] An opening 302 is formed in the bonding layer 300 at a position between the expanded diameter portion 161 and the gas hole 261. An end of the gas hole 261 on the surface 210 side is connected to the expanded diameter portion 161 of the second gas hole 160 through the opening 302. An end of the gas hole 261 on the opposite side to the above end is connected to a distribution flow path 272 formed inside the base plate 200.

[0043] The distribution flow path 272 is a flow path formed to distribute helium gas supplied from the outside to each of the multiple gas holes 261. The distribution flow path 272 is routed along a path that passes directly below all of the gas holes 261. A configuration may be adopted in which multiple distribution flow paths 272 are formed, and the supply of helium gas to the gas holes 261 is divided into multiple systems. With such a configuration, for example, the pressure of the helium gas supplied to the gas holes 261 on the central side and the pressure of the helium gas supplied to the gas holes 261 on the outer periphery side can be made different from each other. The distribution flow path 272 may be connected to the distribution flow path 271.

[0044] An air-permeable member 620 is disposed inside the gas hole 261. The air-permeable member 620 is a substantially cylindrical member that is air-permeable. In this embodiment, porous alumina is used as the air-permeable member 620. The air-permeable member 620 may be a member in which a plurality of air holes extending linearly from one end to the other end are formed, or may be a member in which a mesh-like flow path is formed.

[0045] The configurations of the first ventilation member 400 and the second ventilation member 500 will be described. Fig. 2(A) shows a schematic cross section of the cylindrical second ventilation member 500 cut along a plane passing through its central axis. Fig. 2(B) shows a schematic cross section of the cylindrical first ventilation member 400 cut along a plane passing through its central axis. Fig. 3(A) shows the configuration of the second ventilation member 500 when viewed from above. Fig. 3(B) shows the configuration of the first ventilation member 400 when viewed from above.

[0046] First, the first ventilation member 400 will be described. The first ventilation member 400 has an outer peripheral portion 410 and a central portion 420. The outer peripheral portion 410 is a cylindrical portion located on the outermost side of the first ventilation member 400. The entire outer peripheral portion 410 is made of dense alumina and has no air permeability.

[0047] The central portion 420 is a generally cylindrical portion located inside the outer peripheral portion 410. A plurality of first ventilation holes 421 are formed in the central portion 420. The first ventilation holes 421 are circular through-holes formed to extend linearly from the upper end face 401 of the first ventilation member 400 to the lower end face 402 in FIG. 2. Each first ventilation hole 421 extends in a direction perpendicular to the end face 401 (i.e., along the central axis of the first ventilation member 400). As shown in FIG. 3(B), a plurality of first ventilation holes 421 are formed and arranged to be uniformly distributed on the end face 401, but only two of these first ventilation holes 421 are shown in FIG. 2(B). Helium gas supplied from the gas holes 251 of the base plate 200 flows through each first ventilation hole 421 toward the end face 401. In this way, the central portion 420 is a breathable portion.

[0048] 2(B), the hatching is different between the outer peripheral portion 410 and the central portion 420, but in reality, there is no difference in the materials that make up the two portions. The only difference between the outer peripheral portion 410 and the central portion 420 is whether or not a plurality of first air holes 421 are formed.

[0049] First vent holes 421 may be formed so as to be uniformly distributed on end surface 401 of center portion 420, or a region without first vent holes 421 may be provided on part of end surface 401. For example, first vent holes 421 may not be provided in a region that overlaps, in top view, with a downstream portion of first gas hole 150 (a small-diameter portion that serves as the final gas outlet). With this configuration, discharge in the path through first gas hole 150 can be suppressed.

[0050] Next, the second ventilation member 500 will be described. The second ventilation member 500 has an outer peripheral portion 510 and a central portion 520. The outer peripheral portion 510 is a cylindrical portion located on the outermost side of the second ventilation member 500. The entire outer peripheral portion 510 is made of dense alumina and has no air permeability.

[0051] The central portion 520 is a generally cylindrical portion located inside the outer peripheral portion 510. A plurality of second ventilation holes 521 are formed in the central portion 520. The second ventilation holes 521 are circular through-holes formed to extend linearly from the upper end face 501 of the second ventilation member 500 to the lower end face 502 in FIG. 2. The direction in which each second ventilation hole 521 extends is perpendicular to the end face 501 (i.e., the direction along the central axis of the second ventilation member 500). As shown in FIG. 3(A), a plurality of second ventilation holes 521 are formed and are arranged to be uniformly distributed on the end face 501, but only two of these second ventilation holes 521 are shown in FIG. 2(A). Helium gas supplied from the gas holes 261 of the base plate 200 flows through each second ventilation hole 521 toward the end face 501. In this way, the central portion 520 is a breathable portion.

[0052] 2(A), the hatching is different between outer peripheral portion 510 and central portion 520, but in reality, there is no difference in the materials that make up the two. The only difference between outer peripheral portion 510 and central portion 520 is whether multiple second air holes 521 are formed or not.

[0053] Second vent holes 521 may be formed so as to be uniformly distributed on end surface 501 of center portion 520, or a region without second vent holes 521 may be provided on part of end surface 501. For example, second vent holes 521 may not be provided in a region that overlaps, in top view, with a downstream portion of second gas hole 160 (a small-diameter portion that serves as the final gas outlet). With this configuration, discharge in the path through second gas hole 160 can be suppressed.

[0054] The first ventilation member 400 and the second ventilation member 500 configured as above can be manufactured by, for example, extrusion molding.

[0055] 2, the height dimension L2 of the second ventilation member 500 is smaller than the height dimension L1 of the first ventilation member 400. The "height dimension" refers to the dimension in the direction perpendicular to the surface 110, which is the placement surface, and refers to the dimension in the up-down direction in FIGS.

[0056] Instead of such a configuration, it is also possible to make the height dimensions of both the first ventilation member 400 and the second ventilation member 500 the same. Specifically, it is also possible to shorten the height dimension L1 of the first ventilation member 400 so that it is the same as the height dimension L2 of the second ventilation member 500, thereby sharing parts.

[0057] However, with such a configuration, the height dimension L1 of the first ventilation member 400 becomes too short compared to the overall length of the first gas hole 150, and it may not be possible to sufficiently suppress the occurrence of discharge through the first gas hole 150.

[0058] Therefore, in this embodiment, the height dimension L1 of the first ventilation member 400 is made longer than the height dimension L2 of the second ventilation member 500. In other words, ventilation members with appropriate height dimensions corresponding to the lengths of the first gas holes 150 and the second gas holes 160 are arranged in each of them. By arranging the first ventilation member 400 so that it occupies almost the entire first gas hole 150 and the second ventilation member 500 so that it occupies almost the entire second gas hole 160, it is possible to sufficiently suppress the occurrence of electric discharge through the first gas hole 150 or the second gas hole 160.

[0059] The height dimension L1 of the first ventilation member 400 is preferably set to be larger than the thickness of the second portion 102 of the dielectric substrate 100.

[0060] As described above, the first ventilation member 400 is formed with a plurality of first ventilation holes 421 extending from its one end (end surface 401) to its other end (end surface 402). The second ventilation member 500 is also formed with a plurality of second ventilation holes 521 extending from its one end (end surface 501) to its other end (end surface 502). This configuration ensures ventilation while preventing discharge. In this embodiment, the flow path length of the first ventilation hole 421 is the same as the height dimension L1 of the first ventilation member 400. The flow path length of the second ventilation hole 521 is the same as the height dimension L2 of the second ventilation member 500.

[0061] Because the second ventilation member 500 is disposed in the thin second portion 102, its height dimension L2 is small. For this reason, there is a concern that discharge through the second gas holes 160 may not be sufficiently prevented. Therefore, in this embodiment, as shown in FIG. 3 , the inner diameter D2 of the second ventilation hole 521 is made smaller than the inner diameter D1 of the first ventilation hole 421. By making the inner diameter D2 of the second ventilation hole 521 smaller, the withstand voltage performance of the second ventilation member 500, which has a small height dimension L2, can be improved and brought closer to that of the first ventilation member 400.

[0062] If the inner diameter D2 of the second ventilation hole 521 is made small as described above, the air permeability of the second ventilation member 500 may be reduced too much, making it impossible to supply a sufficient flow rate of helium gas to the annular member RE side. Therefore, in this embodiment, the total number of second ventilation holes 521 formed in one second ventilation member 500 is made greater than the total number of first ventilation holes 421 formed in one first ventilation member 400. This makes it possible to ensure sufficient air permeability of the second ventilation member 500.

[0063] 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.

[0064] This embodiment differs from the first embodiment in the configuration of the second ventilation member 500. Fig. 4(A) shows the configuration of the second ventilation member 500 according to this embodiment as a schematic cross-sectional view similar to Fig. 2(A). Note that Fig. 4(B) shows the configuration of the first ventilation member 400 according to this embodiment for reference, but this configuration is the same as the configuration in the first embodiment shown in Fig. 2(B).

[0065] 4(A) shows the central axis AX of the second ventilation member 500. The central axis AX can also be said to be an axis indicating the normal direction of the surface 110, which is the placement surface. "θ" shown in the figure represents the inclination angle of the second ventilation hole 521 with respect to the normal direction.

[0066] In the second ventilation member 500 of the present embodiment, the second ventilation holes 521 extend obliquely so that the inclination angle of the second ventilation holes 521 with respect to the normal direction is larger than the inclination angle of the first ventilation holes 421 with respect to the normal direction (0 degrees in the example of FIG. 4(B)). As a result, the flow path length of the second ventilation holes 521 is longer than the height dimension L2 of the second ventilation member 500, and the voltage resistance performance of the second ventilation member 500 is further improved compared to the first embodiment.

[0067] Such a second ventilation member 500 may be obtained, for example, by previously preparing a porous member having a plurality of second ventilation holes 521 formed therein and then cutting the porous member at an angle to form a cylindrical member. In other words, the porous member may be cut out so as to have a cylindrical shape with a central axis tilted relative to the second ventilation holes 521. Thereafter, the outer peripheral portion 510 may be provided so as to cover the outer periphery of the member (i.e., the central portion 520). In this case, the central portion 520 and the outer peripheral portion 510 may be formed in advance as separate members, and then the two may be joined together by, for example, adhesive. Alternatively, the two members may be integrated by sintering.

[0068] A third embodiment will be described below. The following mainly describes the differences from the first embodiment, and the description of the commonalities with the first embodiment will be omitted as appropriate.

[0069] This embodiment also differs from the first embodiment in the configuration of the second ventilation member 500. Fig. 5 shows a schematic perspective view of the configuration of the second ventilation member 500 according to this embodiment.

[0070] In the second ventilation member 500 of this embodiment, the second ventilation hole 521 does not extend linearly, but is formed so as to extend spirally from end face 501 to end face 502. On the other hand, the first ventilation hole 421 (not shown) is formed so as to extend linearly, similar to the first embodiment in Fig. 2. Note that a plurality of spiral second ventilation holes 521 are formed in one second ventilation member 500, but only one second ventilation hole 521 is shown in Fig. 5.

[0071] In this embodiment, the flow path length of the spiral second ventilation hole 521 is longer than the height dimension L2 of the second ventilation member 500. Therefore, the voltage resistance performance of the second ventilation member 500 is further improved compared to the first embodiment.

[0072] 5 can be produced, for example, by placing a spiral-shaped core in a green body before sintering and burning off the core during sintering. The second ventilation member 500 may also be produced using a 3D printer.

[0073] 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.

[0074] This embodiment differs from the first embodiment in the configurations of the first ventilation member 400 and the second ventilation member 500. Fig. 6(A) shows the configuration of the second ventilation member 500 according to this embodiment as a schematic cross-sectional view similar to Fig. 2(A). Fig. 6(B) shows the configuration of the first ventilation member 400 according to this embodiment as a schematic cross-sectional view similar to Fig. 2(B).

[0075] In the second ventilation member 500 of this embodiment, the entire central portion 520 is configured as a porous member in which a mesh-like flow path is formed. Similarly, in the first ventilation member 400 of this embodiment, the entire central portion 420 is configured as a porous member in which a mesh-like flow path is formed. However, the porosity of the central portion 520 (i.e., the porosity of the second ventilation member 500) is smaller than the porosity of the central portion 420 (i.e., the porosity of the first ventilation member 400). With this configuration, the voltage resistance performance of the second ventilation member 500 can be improved. Note that the mesh-like flow path may be formed in only a part (the central portion 520) of the second ventilation member 500, or the entire second ventilation member 500. Similarly, the mesh-like flow path may be formed in only a part (the central portion 420) of the first ventilation member 400, or the entire first ventilation member 400.

[0076] The fifth 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.

[0077] Fig. 7(A) shows the configuration of the second ventilation member 500 according to this embodiment. The configuration of the second ventilation member 500 according to this embodiment is the same as the configuration of the second ventilation member 500 according to the first embodiment (Fig. 2(A)). Fig. 7(B) shows the configuration of the first ventilation member 400 according to this embodiment. The configuration of the first ventilation member 400 according to this embodiment is the same as the configuration of the first ventilation member 400 according to the fourth embodiment (Fig. 6(A)).

[0078] That is, in this embodiment, the first ventilation member 400 is configured as a member in which a mesh-like flow path is formed, and the second ventilation member 500 is configured as a member in which a plurality of second ventilation holes 521 extending from one end to the other end are formed. Even with this configuration, it is possible to improve the voltage resistance performance of the second ventilation member 500, and to achieve the same effects as those described in the first embodiment, etc.

[0079] 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]

[0080] 10: Electrostatic chuck 100: Dielectric substrate 101: Part 1 102:Second part 110: Face 150: First gas hole 160: Second gas hole 400: First ventilation member 421: First ventilation hole 500: Second ventilation member 521: Second ventilation hole W: Substrate

Claims

1. a first portion including a placement surface on which an object to be attracted is placed; a second portion that protrudes further outward from the outer circumferential end of the first portion and is thinner than the first portion, a first gas hole is formed in the first portion; a first ventilation member having air permeability is disposed inside the first gas hole; A second gas hole is formed in the second portion, a second ventilation member having air permeability is disposed inside the second gas hole, When the dimension in the direction perpendicular to the mounting surface is defined as the height dimension, The electrostatic chuck is characterized in that the height dimension of the second ventilation member is smaller than the height dimension of the first ventilation member.

2. The first ventilation member has a plurality of first ventilation holes formed therein, the first ventilation member extending from one end to the other end thereof, 2. The electrostatic chuck according to claim 1, wherein the second ventilation member has a plurality of second ventilation holes formed therein, the second ventilation member extending from one end to the other end thereof.

3. 3. The electrostatic chuck according to claim 2, wherein the inner diameter of the second vent hole is smaller than the inner diameter of the first vent hole.

4. 4. The electrostatic chuck according to claim 3, wherein a total number of the second ventilation holes formed in one of the second ventilation members is greater than a total number of the first ventilation holes formed in one of the first ventilation members.

5. 3. The electrostatic chuck according to claim 2, wherein an inclination angle of the second vent hole with respect to a normal direction of the mounting surface is larger than an inclination angle of the first vent hole with respect to the normal direction.

6. 3. The electrostatic chuck according to claim 2, wherein the first vent hole extends linearly, and the second vent hole extends spirally.

7. The first ventilation member and the second ventilation member are both members in which a mesh-like flow path is formed, 2. The electrostatic chuck according to claim 1, wherein the porosity of the second ventilation member is smaller than the porosity of the first ventilation member.

8. The first ventilation member is a member having a mesh-like flow path formed therein, 2. The electrostatic chuck according to claim 1, wherein the second ventilation member is a member having a plurality of ventilation holes formed therein and extending from one end to the other end thereof.

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