Holding device

Abstract

To provide a holding device that can improve the insulation properties and prevent the suction force from decreasing.SOLUTION: An electrostatic chuck 10 includes a ceramic member 41 having a suction surface 51 and a lower surface 52 provided on the side opposite to the suction surface 51 in the Z-axis direction, a chuck electrode 53 located closest to the suction surface 51 from among the electrodes provided inside the ceramic member 41, and a via 81 connected to the chuck electrode 53 extending in the Z-axis direction, and holds a wafer W on the suction surface 51 of the ceramic member 41. In the electrostatic chuck 10, a plurality of convex portions 72 are formed on the suction surface 51, and the via 81 is arranged so as to overlap with the convex portions 72 when viewed in the Z-axis direction.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a holding device for holding an object. [Background technology]

[0002] As a holding device, for example, Patent Document 1 discloses an electrostatic chuck having a plurality of convex portions formed on an attracting surface and including internal electrodes such as an attracting electrode and a heater electrode. In this electrostatic chuck, a terminal pad to which power is supplied from the outside via a power supply terminal is connected to the internal electrode via a via and an intermediate conductor layer. This allows power to be supplied from an external power source to the internal electrode via the power supply terminal, the terminal pad, the via, and the intermediate conductor layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-228361 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above electrostatic chuck, since surface processing such as polishing and blasting is performed to form a plurality of convex portions on the attracting surface, the thickness of the insulating layer between the internal electrode and the attracting surface is partially reduced, and there is a risk of dielectric breakdown occurring in the portion where the thickness is reduced. In particular, in the portion where the internal electrode is connected to the via, the via pushes up the internal electrode, causing the internal electrode to rise toward the attracting surface, further reducing the thickness of the insulating layer, making dielectric breakdown more likely to occur.

[0005] Here, if the thickness of the insulating layer on the attracting surface side is increased, the insulating properties are improved and it is possible to prevent the occurrence of dielectric breakdown. However, if the thickness of the insulating layer on the attracting surface side is increased, in the case where the internal electrode is a chuck electrode, the distance between the chuck electrode and the target object increases, and the chucking force for holding the target object decreases.

[0006] Therefore, the present disclosure has been made to solve the above-mentioned problems, and aims to provide a holding device that can improve insulation properties and prevent a decrease in suction force. [Means for solving the problem]

[0007] In order to solve the above problems, one aspect of the present disclosure is to A holding device for holding an object on the first surface of the plate-like member, the holding device comprising: a plate-like member having a first surface and a second surface provided on the opposite side of the first surface in a first direction; an internal electrode located closest to the first surface among electrodes provided inside the plate-like member; and a conductive member connected to the internal electrode extending in the first direction, the holding device comprising: A plurality of protrusions are formed on the first surface, the internal electrode is formed across the plurality of protrusions when viewed from the first direction, The conductive member is disposed so as to overlap the protrusion when viewed from the first direction. And, The conductive members are a plurality of vias connected to the internal electrodes. It is characterized by:

[0008] In this holding device, the conductive member is arranged so as to overlap the convex portion when viewed from the first direction (top view). Here, "overlapping the convex portion" includes the case where the conductive member is completely contained within the convex portion when viewed from the top, as well as the case where a part of the conductive member overlaps the convex portion. As a result, the arrangement portion of the conductive member connected to the internal electrode, where dielectric breakdown is most likely to occur, is arranged so as to overlap the convex portion formed on the first surface. Therefore, the thickness of the insulating layer in the arrangement portion of the conductive member is not reduced by the surface processing performed on the first surface to form the convex portion. Therefore, it is possible to improve the insulation and prevent the occurrence of dielectric breakdown. In addition, since the thickness of the insulating layer on the first surface side is not increased, the suction force of the holding device is not reduced even when the internal electrode is a chuck electrode.

[0010] For example, a method of forming vias is to form through-holes in a green sheet and fill the through-holes with metallization ink that will become vias through a mask. Generally, when filling the through-holes with metallization ink, the vias are formed so that they rise up by the thickness of the mask relative to the thickness of the green sheet, so that a protrusion occurs in the via arrangement portion (localized rise on the first surface). Therefore, if the first surface is subjected to surface processing to form a protrusion, the thickness of the insulating layer in the via arrangement portion may decrease.

[0011] By doing so, a convex portion is formed directly above at least two of the vias connected to the internal electrodes, so the thickness of the insulating layer at the arrangement portion of the vias connected to the internal electrodes is not reduced. Therefore, the insulation is improved, and it is possible to prevent the occurrence of dielectric breakdown. In addition, since the thickness of the insulating layer is not increased, the suction force of the holding device is not reduced.

[0012] In the above-mentioned holding device, The conductive members are preferably all vias connected to the internal electrodes.

[0013] By doing so, a convex portion is formed directly above the arrangement portion of all the vias connected to the internal electrode, so that the thickness of the insulating layer at the arrangement portion of the vias connected to the internal electrode is not reduced. Therefore, the insulation property is further improved, and it is possible to reliably prevent the occurrence of dielectric breakdown. In addition, since the thickness of the insulating layer is not increased, the chucking force of the holding device is not reduced even if the internal electrode is a chuck electrode.

[0014] In the above-mentioned holding device, The internal electrode has a protruding portion that protrudes toward the first surface side, It is preferable that the protrusion overlaps the plurality of vias when viewed from the first direction.

[0015] Since the thickness of the insulating layer at the protruding portion of the internal electrode is thinner than other portions, this is the portion where dielectric breakdown is most likely to occur. Therefore, by making the protruding portion overlap with the multiple vias when viewed from the first direction (top view) in this way, a convex portion is disposed directly above the protruding portion. This prevents the thickness of the insulating layer at the protruding portion of the internal electrode from decreasing, improving insulation and preventing dielectric breakdown from occurring. In addition, since the thickness of the insulating layer at the protruding portion does not increase, the suction force of the holding device does not decrease even if the internal electrode is a chuck electrode.

[0016] In the above-mentioned holding device, It is preferable that all of the vias are arranged so as to overlap one-to-one with the protruding portions.

[0017] In this way, compared to when multiple vias are arranged so as to overlap one protruding portion, the vias are arranged farther apart, so that it is possible to prevent the generation of temperature singularities (parts that become hotter than other parts) on the first surface of the plate-shaped member due to heat generation from the vias themselves. Therefore, since the protruding portion is formed directly above the via arrangement portion, the thickness of the insulating layer in the via arrangement portion connected to the internal electrode does not decrease. Therefore, since the insulation property is further improved, it is possible to reliably prevent the occurrence of dielectric breakdown and achieve temperature uniformity on the first surface of the plate-shaped member.

[0018] Another aspect of the present disclosure made to solve the above problem is: A holding device for holding an object on the first surface of the plate-like member, the holding device comprising: a plate-like member having a first surface and a second surface provided on the opposite side of the first surface in a first direction; an internal electrode located closest to the first surface among electrodes provided inside the plate-like member; and a conductive member connected to the internal electrode extending in the first direction, the holding device comprising: A plurality of protrusions are formed on the first surface, the internal electrode is formed across the plurality of protrusions when viewed from the first direction, the conductive member is disposed so as to overlap the protrusion when viewed from the first direction, the conductive members are a plurality of vias connected to the internal electrodes, a connection pad connected to the plurality of vias; a plurality of second vias connected to the connection pads and disposed on the second surface side; the plurality of vias and the plurality of second vias are arranged to be shifted in a second direction perpendicular to the first direction so as not to overlap when viewed from the first direction; It is characterized by:

[0019] If the via and the second via are arranged in the same position (in a straight line in the first direction), the protruding portions of the via arrangement portion overlap, resulting in a large amount of protrusion toward the first surface side in the via arrangement portion. If this amount of protrusion becomes large, the thickness of the insulating layer decreases, making dielectric breakdown more likely to occur. By doing this, it is possible to prevent the amount of protrusion toward the first surface side of the via arrangement portion from becoming large. As a result, the thickness of the insulating layer in the via arrangement portion does not decrease, improving insulation and preventing dielectric breakdown.

[0020] In the above-mentioned holding device, It is preferable that the second vias are arranged so as to overlap the protrusion when viewed from the first direction.

[0021] This prevents a decrease in the thickness of the insulating layer even in the area where the second via is arranged, and improves the insulation properties even in the area where the second via is arranged, making it possible to reliably prevent the occurrence of dielectric breakdown. Effect of the Invention

[0022] According to the present disclosure, it is possible to provide a holding device that can improve insulation properties and prevent a decrease in adsorptive force. [Brief description of the drawings]

[0023] [Figure 1] 1 is a schematic perspective view of an electrostatic chuck according to an embodiment; [Diagram 2] 1 is a schematic configuration diagram of an electrostatic chuck of an embodiment of the present invention taken along an XZ cross section. [Diagram 3] 1 is a schematic configuration diagram of an electrostatic chuck in an XY plane according to an embodiment. [Figure 4] 4 is an enlarged cross-sectional view of a via arrangement portion and its vicinity in the ceramic member. FIG. [Diagram 5] FIG. 2 is a cross-sectional view showing a state of a ceramic member before polishing. [Figure 6] FIG. 4 is a cross-sectional view showing the state of a ceramic member after polishing (before blasting). [Figure 7] FIG. 13 is a diagram showing an example in which a via completely overlaps a protrusion as viewed in the Z-axis direction. [Figure 8] FIG. 13 is a diagram showing an example in which a via partially overlaps a protrusion as viewed in the Z-axis direction. [Figure 9] FIG. 13 is a diagram showing an example in which a plurality of vias overlap one protrusion as viewed in the Z-axis direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A holding device according to an embodiment of the present disclosure will be described in detail with reference to the drawings. In this embodiment, a case where the holding device is applied to an electrostatic chuck for holding a semiconductor wafer will be described.

[0025] <Overall structure of electrostatic chuck> The electrostatic chuck of this embodiment will be described with reference to Fig. 1 to Fig. 3. The electrostatic chuck 10 is a device that attracts and holds an object (e.g., a wafer W) by electrostatic attraction, and is used, for example, to fix the wafer W in a vacuum chamber of a semiconductor manufacturing device. As shown in Fig. 1, the electrostatic chuck 10 has a ceramic member 41 which is a plate-shaped member, a base member 42, a bonding layer 43, and the like.

[0026] For convenience of explanation, in the following description, the X, Y and Z axes are defined as shown in Fig. 1. Here, the Z axis is an axis in the direction of the central axis Ca of the electrostatic chuck 10 (the vertical direction in Fig. 1), and the X and Y axes are axes in the radial direction of the electrostatic chuck 10. The Z axis direction (i.e., the direction of the central axis Ca) is an example of a "first direction" in the present disclosure, and the Y axis direction and the Z axis direction (i.e., the radial direction of the electrostatic chuck 10) are an example of a "second direction" in the present disclosure.

[0027] The ceramic member 41 is, for example, a disk-shaped member, and is made of ceramics. Various ceramics can be used as the ceramic, but from the viewpoints of strength, wear resistance, plasma resistance, etc., it is preferable to use ceramics whose main component is, for example, aluminum oxide (alumina, Al2O3) or aluminum nitride (AlN). Note that the main component here means the component with the highest content (for example, a component with a volume content of 90 vol% or more).

[0028] The ceramic member 41 has a diameter of, for example, about 150 mm to 300 mm and a thickness of, for example, about 2 mm to 6 mm. The ceramic member 41 desirably has a thermal conductivity in the range of 10 to 50 W / mK (more preferably, 18 to 30 W / mK, for example, 20 W / mK).

[0029] 1 and 2, the ceramic member 41 has an adsorption surface 51 which is an upper surface, and a lower surface 52 which is provided on the opposite side to the adsorption surface 51 in the central axis direction (i.e., the Z-axis direction) of the ceramic member 41. The ceramic member 41 holds the wafer W on the adsorption surface 51. The adsorption surface 51 is an example of a "first surface" in the present disclosure, and the lower surface 52 is an example of a "second surface" in the present disclosure.

[0030] As shown in Figs. 2 and 3, the adsorption surface 51 has an annular convex portion 71 formed near its outer edge, and a plurality of independent columnar convex portions 72 are formed inside the annular convex portion 71. The annular convex portion 71 is also called a seal band. The cross section (XZ cross section) of the annular convex portion 71 has a substantially rectangular shape as shown in Fig. 2. The height (dimension in the Z-axis direction) of the annular convex portion 71 is, for example, about 10 µm to 20 µm. The width (dimension in the X-axis direction) of the annular convex portion 71 is, for example, about 0.5 mm to 5.0 mm.

[0031] As shown in FIG. 3, each of the protrusions 72 has a substantially circular shape when viewed in the Z-axis direction, and is disposed at substantially equal intervals. The cross-sectional shape (XZ cross-section) of each of the protrusions 72 is substantially rectangular, as shown in FIG. 2. The height of the protrusions 72 is substantially the same as the height of the annular protrusion 71, and is, for example, about 10 μm to 20 μm. The width of the protrusions 72 (maximum diameter of the protrusions 72 when viewed in the Z-axis direction) is, for example, about 0.5 mm to 1.5 mm. The portion of the adsorption surface 51 of the ceramic member 41 inside the annular protrusion 71 where the protrusions 72 are not formed is a recess 73.

[0032] The wafer W is supported by the annular convex portion 71 and the multiple convex portions 72 on the attracting surface 51 of the ceramic member 41 and is held by the electrostatic chuck 10. When the wafer W is held by the electrostatic chuck 10, a space exists between the surface (lower surface) of the wafer W and the attracting surface 51 (more specifically, the concave portion 73 of the attracting surface 51) of the ceramic member 41. An inert gas (e.g., helium gas) is supplied to this space.

[0033] As shown in FIG. 2, the ceramic member 41 includes a chuck electrode 53 therein. The chuck electrode 53 is, for example, substantially circular as viewed in the Z-axis direction, and is made of a conductive material (for example, tungsten or molybdenum). The chuck electrode 53 is an example of an "internal electrode" in the present disclosure. The wafer W is attracted and held on the attraction surface 51 by electrostatic attraction generated by applying a voltage to the chuck electrode 53 through the vias 81a and 81b, the connection pad 82, the via 83a, the terminal pad 84, and a power supply terminal 85 connected to the power supply (not shown). A plurality of vias 81 including the vias 81a and 81b are connected to the chuck electrode 53, and a plurality of vias 83 including the via 83a are connected to the connection pad 82. The diameter of the vias 81 and 83 is, for example, about 0.3 to 0.6 mm. Details of the vias 81 (81a and 81b), the via 83 (83a), and the like will be described later.

[0034] 1, the base member 42 is formed in a cylindrical shape (more specifically, a stepped cylindrical shape formed by overlapping two cylinders of different diameters with a common central axis (the upper part of the cylindrical shape with a smaller diameter is placed on the lower part of the cylindrical shape with a larger diameter)). The base member 42 is preferably formed of a metal (for example, aluminum or an aluminum alloy), but may be made of a material other than metal.

[0035] 1 and 2, the base member 42 has an upper surface 61 and a lower surface 62 provided on the opposite side to the upper surface 61 in the direction of the central axis Ca (see FIG. 3) of the base member 42 (ceramic member 41) (i.e., the Z-axis direction). The upper surface 61 is an example of a "third surface" in the present disclosure, and the lower surface 62 is an example of a "fourth surface" in the present disclosure.

[0036] The diameter of the base member 42 is, for example, about 150 mm to 300 mm at the upper portion and about 180 mm to 350 mm at the lower portion. The thickness (dimension in the Z-axis direction) of the base member 42 is, for example, about 20 mm to 50 mm. The thermal conductivity of the base member 42 (assumed to be aluminum) is desirably within the range of 180 to 250 W / mK (preferably, about 230 W / mK).

[0037] The base member 42 is joined to the ceramic member 41 by the joining layer 43 disposed between the lower surface 52 of the ceramic member 41 and the upper surface 61 of the base member 42. In this manner, the lower surface 52 of the ceramic member 41 and the upper surface 61 of the base member 42 are thermally connected. The joining layer 43 is made of an adhesive material such as a silicone resin, an acrylic resin, or an epoxy resin. The thickness (dimension in the Z-axis direction) of the joining layer 43 is, for example, about 0.1 mm to 1.0 mm. The thermal conductivity of the joining layer 43 is, for example, 1.0 W / mK. The thermal conductivity of the joining layer 43 (assuming a silicone resin) is desirably within a range of 0.1 to 2.0 W / mK (preferably, 0.5 to 1.5 W / mK).

[0038] 2, the base member 42 is provided with a coolant flow passage 63 for flowing a coolant (e.g., a fluorine-based inert liquid, water, etc.). The coolant flow passage 63 is connected to a supply port and a discharge port (not shown) provided on the lower surface 62 of the base member 42, and the coolant supplied to the base member 42 from the supply port flows through the coolant flow passage 63 and is discharged from the discharge port to the outside of the base member 42. By flowing the coolant through the coolant flow passage 63 in this manner, the base member 42 is cooled, and thereby the ceramic member 41 is cooled via the bonding layer 43.

[0039] <About Via> Here, the vias 81 (81a, 81b) and the vias 83 (83a) provided in the ceramic member 41 will be described with reference to FIG. 4. As shown in FIG. 4, the vias 81 (81a, 81b) are arranged so as to extend in the Z-axis direction toward the lower surface 52 side from the chuck electrode 53, one end is connected to the chuck electrode 53, and the other end is connected to the connection pad 82. As a result, the chuck electrode 53 and the connection pad 82 are electrically connected to each other through the vias 81 (81a, 81b). The via 83 (83a) is arranged on the lower surface 52 side from the connection pad 82, one end is connected to the connection pad 82, and the other end is connected to the terminal pad 84. As a result, the connection pad 82 and the terminal pad 84 are electrically connected to each other through the via 83 (83a). In this way, the terminal pad 84 is electrically connected to the chuck electrode 53 through the vias 83 (83a), the connection pad 82, and the vias 81 (81a, 81b). The via 83 (83a) is an example of a "second via" in the present disclosure.

[0040] The vias 81 (81a, 81b) and the vias 83 (83a) are formed by filling the through holes with metallized ink. Therefore, as shown in FIG. 4, the vias 81a, 81b rise toward the suction surface 51 by the thickness of the mask used when filling the ink. Therefore, protrusions 53a, 53b are formed on the chuck electrode 53 at the positions where the vias 81a, 81b are arranged. That is, the protrusions 53a, 53b overlap the vias 81a, 81b when viewed in the Z-axis direction. Furthermore, a protrusion 82a is formed on the connection pad 82 at the position where the via 83a is arranged. This protrusion 82a overlaps the via 83a when viewed in the Z-axis direction.

[0041] Therefore, as shown in Fig. 5, on the upper surface 51 of the ceramic member 41 before the convex portion 72 is formed, the portions directly above the protruding portions 53a, 53b, and 82a are raised. The protruding portions 53a and 53b, which are closer to the attracting surface 51, protrude more than the protruding portion 82a. Then, before the convex portion 72 is formed, the upper surface 51 of the ceramic member 41 is polished to make it flat. After this polishing, as shown in Fig. 6, the thickness of the ceramic on the attracting surface 51 side of the chuck electrode 53 becomes smaller in the protruding portions 53a and 53b than in other portions, and therefore the insulation property is reduced in these portions, which may cause dielectric breakdown.

[0042] If the recess 73 is located directly above the protrusions 53a and 53b when the protrusions 72 are formed by the blasting process performed after polishing, the thickness of the ceramic on the attracting surface 51 side of the chuck electrode 53 becomes even smaller, so that dielectric breakdown is more likely to occur. Note that, although the occurrence of dielectric breakdown can be avoided by increasing the thickness of the ceramic between the chuck electrode 53 and the recess 73, it is practically difficult to increase the thickness of the ceramic on the attracting surface 51 side of the chuck electrode 53 because the attracting force of the electrostatic chuck 10 decreases. Note that, in FIGS. 4 to 6, vias 81a and 81b that are part of the plurality of vias 81 connected to the chuck electrode 53, and via 83a that is part of the plurality of vias 83 connected to the connection pad 82 are shown.

[0043] 4, in the electrostatic chuck 10 of the present embodiment, the vias 81a, 81b and the via 83a are arranged so as to overlap with the protrusion 72 when viewed in the Z axis direction. As a result, the protrusions 53a, 53b formed on the chuck electrode 53 and the protrusion 82a formed on the connection pad 82 are arranged so as to overlap with the protrusion 72 when viewed in the Z axis direction.

[0044] The vias 81a and 81b are part of a plurality of vias 81 connected to the chuck electrode 53, and these vias 81 (81a, 81b) are located closest to the chucking surface 51 among the vias provided in the ceramic member 41. The via 83a is shifted in the radial direction (X-axis direction or Y-axis direction) so as not to overlap with the vias 81a and 81b when viewed in the Z-axis direction. The via 83a is part of a plurality of vias 83 connected to the connection pad 82.

[0045] Here, "overlapping with the protrusion 72" means that, as viewed in the Z-axis direction, the vias 81, 83 (or protrusions) are completely contained within (completely overlap) the protrusion 72 as shown in Fig. 7, and also includes a case in which a part of the vias 81, 83 (or protrusions) protrudes from (partially overlaps with) the protrusion 72 as shown in Fig. 8. However, since a partial overlap reduces the effect of preventing dielectric breakdown compared to a complete overlap, it is desirable that the vias 81a, 81b, 83a (or protrusions 53a, 53b, 82a) are disposed so as to completely overlap with the protrusion 72 as viewed in the Z-axis direction.

[0046] As described above, according to the electrostatic chuck 10 of the present embodiment, the vias 81a, 81b and the protruding portions 53a, 53b are arranged so as to overlap the convex portion 72 when viewed in the Z-axis direction. As a result, the arrangement portion of the vias 81a, 81b connected to the chuck electrode 53, where dielectric breakdown is most likely to occur, is arranged so as to overlap the convex portion 72 formed on the attracting surface 51. Therefore, the thickness of the ceramics (insulating layer) on the attracting surface 51 side from the chuck electrode 53 in the arrangement portion of the vias 81a, 81b is not reduced by the surface processing (polishing and blasting) performed to form the convex portion 72. In this embodiment, the distance (thickness of the ceramics) from the upper surface of the chuck electrode 53 to the upper surface of the convex portion 72 is about 300 μm. Therefore, the insulation property of the electrostatic chuck 10 can be improved, and the occurrence of dielectric breakdown can be prevented. In addition, the thickness of the ceramics on the attracting surface 51 side from the chuck electrode 53 does not increase, so that the attracting force of the electrostatic chuck 10 is not reduced.

[0047] In addition, the via 83 (83a) is arranged so as to be shifted in the radial direction (X-axis direction or Y-axis direction) so as not to overlap with the via 81 (81a, 81b) when viewed in the Z-axis direction, and therefore, it is possible to prevent the amount of thrust toward the attracting surface 51 side at the arrangement portion of the via 81 (81a, 81b) from increasing. In other words, by arranging the via 81a or 81b and the via 83a at the same position (in a straight line in the Z-axis direction), the thrust portions of the respective via arrangement portions are piled up, and the amount of thrust toward the attracting surface 51 side at the via arrangement portion increases, and the height (dimension in the Z-axis direction) of the protruding portion 53a or 53b is prevented from increasing. As a result, it is possible to prevent the thickness of the ceramic (insulating layer) on the attracting surface 51 side from the chuck electrode 53 at the arrangement portion of the vias 81a, 81b from decreasing, and therefore, it is possible to improve the insulation property of the electrostatic chuck 10 and prevent the occurrence of dielectric breakdown.

[0048] The vias 81 connected to the chuck electrode 53 other than the vias 81a and 81b and the vias 83 connected to the connection pads 82 other than the vias 83a may be arranged to overlap the protrusions 72 as viewed in the Z-axis direction, as described above. This allows the protrusions 72 to be formed directly above the respective arrangement portions of all the vias 81 (81a, 81b) connected to the chuck electrode 53 and all the vias 83 (83a) connected to the connection pads 82. This makes it possible to prevent a decrease in the thickness of the ceramic on the attracting surface 51 side from the chuck electrode 53 in the respective arrangement portions of all the vias 81 and 83. This further improves the insulating properties of the electrostatic chuck 10, thereby more reliably preventing the occurrence of dielectric breakdown.

[0049] Furthermore, each of the vias 81 and the vias 83 may be arranged to overlap one-to-one with the protruding portion 72 when viewed in the Z-axis direction. In this manner, the vias 81 and the vias 83 are arranged apart from one another, and it is possible to prevent the generation of temperature singular points (portions that become hotter than other portions) in the ceramic member 41 due to heat generation from the vias themselves. Furthermore, compared to the case where a plurality of vias 81 or vias 83 are arranged together so as to overlap one protruding portion 72 (see FIG. 9), the temperature of the via arrangement portion is lower, and therefore it is possible to make it more difficult for dielectric breakdown to occur in the via arrangement portion.

[0050] It should be noted that the above embodiment is merely an example and does not limit the present disclosure in any way, and various improvements and modifications are possible without departing from the spirit and scope of the present disclosure. For example, in the above embodiment, the chuck electrode 53 is exemplified as the internal electrode located closest to the chucking surface 51, but the internal electrode is not limited to the chuck electrode 53 and may be a high-frequency electrode.

[0051] In addition, in the above embodiment, vias 81 (81a, 81b) and vias 83 (83a) are given as examples of conductive members, but in addition to vias, metal terminals, for example, in which a metal rod (molded body) is embedded to effect internal connection, can also be used.

[0052] In the above embodiment, the protrusion 72 and the via 81 or 83 are arranged to overlap one-to-one when viewed in the Z-axis direction, that is, only one of the vias 81 or 83 is arranged to overlap one protrusion 72, but for example, as shown in Fig. 9, multiple vias 81 or 83 can be arranged to overlap one protrusion 72. Note that Fig. 9 illustrates a state in which two vias 81 (83) overlap, but three or more vias can be arranged to overlap. In this way, when multiple vias are arranged to overlap one protrusion 72 when viewed in the Z-axis direction, it is preferable to form the size (e.g., diameter) of the protrusion 72 in the XY plane larger than the case of the one-to-one arrangement as in the above embodiment. [Explanation of symbols]

[0053] 10 Electrostatic Chuck 41 Ceramic materials 42 Base material 51 Adsorption surface 53 Chuck electrode 72 Convex 81 Via 81a Via 81b Via 82 Connection Pad 83 Beer 83a Via 84 Terminal Pad W wafer

Claims

1. A holding device for holding an object on the first surface of the plate-like member, the holding device comprising: a plate-like member having a first surface and a second surface provided on an opposite side to the first surface in a first direction; an internal electrode located closest to the first surface among electrodes provided inside the plate-like member; and a conductive member connected to the internal electrode extending in the first direction, the holding device comprising: A plurality of protrusions are formed on the first surface, the internal electrode is formed across the plurality of protrusions when viewed from the first direction, the conductive member is disposed so as to overlap the protrusion when viewed from the first direction, The conductive members are a plurality of vias connected to the internal electrodes. A holding device characterized in that

2. 2. The holding device according to claim 1, The conductive members are all the vias connected to the internal electrodes. A holding device characterized in that

3. The holding device according to claim 1 or 2, The internal electrode includes a protruding portion that protrudes toward the first surface side, The protrusion overlaps with the plurality of vias when viewed from the first direction. A holding device characterized in that

4. 3. The holding device according to claim 2, All of the vias are arranged to overlap one-to-one with the protrusions. A holding device characterized in that

5. A holding device for holding an object on the first surface of a plate-like member, the holding device comprising: a plate-like member having a first surface and a second surface disposed on the opposite side of the first surface in a first direction; an internal electrode disposed inside the plate-like member and located closest to the first surface; and a conductive member connected to the internal electrode extending in the first direction, the holding device comprising: A plurality of protrusions are formed on the first surface, the internal electrode is formed across the plurality of protrusions when viewed from the first direction, the conductive member is disposed so as to overlap the protrusion when viewed from the first direction, the conductive members are a plurality of vias connected to the internal electrodes, a connection pad connected to the plurality of vias; a plurality of second vias connected to the connection pads and disposed on the second surface side; The plurality of vias and the plurality of second vias are arranged to be shifted in a second direction perpendicular to the first direction so as not to overlap when viewed from the first direction. A holding device characterized in that

6. 6. The holding device according to claim 5, The second vias are arranged to overlap the protrusion when viewed from the first direction. A holding device characterized in that

7. The holding device according to claim 5, The conductive members are all the vias connected to the internal electrodes. A holding device characterized in that

8. A holding device according to claim 5 or claim 7, The internal electrode includes a protruding portion that protrudes toward the first surface side, The protrusion overlaps with the plurality of vias when viewed from the first direction. A holding device characterized in that

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