Holding device

Abstract

To provide a holding device capable of improving an insulation property.SOLUTION: An electrostatic chuck 1 holds a semiconductor wafer W on a holding surface 11 of a plate-like member 10, and comprises: the plate-like member 10 having a chuck electrode 50; a terminal pad 60 and a power feeding terminal 62 connected with the chuck electrode 50 and arranged on a lower surface 12; a base member 20 that has a through-hole 25 where the power feeding terminal 62 is arranged; and a bonding layer 40 arranged between the lower surface 12 of the plate-like member 10 and an upper surface 21 of the base member 20, bonding between the plate-like member 10 and the base member 20. The bonding layer 40 is formed with a bonding layer through-hole 45 communicating with the through-hole 25. An annular convex part 34 that protrudes from the lower surface 12 at least into the bonding layer through-hole 45 is formed around the terminal pad 60 and the power feeding terminal 62 integrally with the plate-like member 10.SELECTED DRAWING: Figure 2

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, an electrostatic chuck described in Patent Document 1 is known. This electrostatic chuck includes a ceramic substrate (first member) that holds a semiconductor wafer on its surface (holding surface) and a metal base member (second member) bonded to the ceramic substrate, and an internal electrode such as a chuck electrode or a heater electrode is disposed inside the ceramic substrate. In addition, in this electrostatic chuck, as a configuration for supplying power to the internal electrode, a first terminal that is conductive to the internal electrode is disposed on the lower surface of the ceramic substrate, and a second terminal that is connected to an external power source at one end and to the first terminal at the other end is disposed in a through hole formed in the base member. In order to insulate the first and second terminals from the base member, an insulating tube is disposed around the terminals. This insulating tube is bonded to the electrostatic chuck by a resin adhesive. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-103321 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the electrostatic chuck is in use, the temperature of the electrostatic chuck rises and falls, which may cause the resin adhesive to deteriorate. In other words, when the temperature rises (high temperature), the adhesive deteriorates due to direct heat application or thermal expansion difference, weakening its adhesiveness, causing gaps to form in the joint area or the adhesive itself to be damaged. On the other hand, when the temperature falls (low temperature), the adhesive itself becomes moist or hardens, and is unable to keep up with the thermal expansion difference, weakening its adhesiveness, causing gaps to form in the joint area or the adhesive itself to be damaged.

[0005] If the resin adhesive deteriorates and a gap appears at the joint or the adhesive itself becomes damaged, the gap or damaged part becomes a leak path, the insulation between the terminal and the base member is broken, and abnormal discharge occurs. In recent years, electrostatic chucks have been increasingly used at high temperatures (250°C or higher), which makes the resin adhesive more susceptible to deterioration, and therefore there is a demand for improved insulation properties in such electrostatic chucks.

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

[0007] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following form: A holding device having a first member including a first surface, a second surface provided on the opposite side to the first surface, and an internal electrode disposed between the first surface and the second surface, a second member including a terminal connected to the internal electrode and disposed on the second surface, a third surface, a fourth surface provided on the opposite side to the third surface, and a through hole penetrating the third surface and the fourth surface and having the terminal disposed therein, and a bonding layer disposed between the second surface of the first member and the third surface of the second member and bonding the first member and the second member, the holding device holding an object on the first surface of the first member, the bonding layer having a bonding layer through hole communicating with the through hole, an annular protrusion protruding from the second surface at least into the bonding layer through hole is formed integrally with the first member around the terminal, and a gap is formed between the protrusion and the through hole. In the through hole, a ring-shaped insulating sleeve is formed at the tip of the protrusion and extends to the fourth surface, and a gap is formed between the sleeve and the through hole. The holding device can be realized in the following forms. In order to solve the above problems, one aspect of the present disclosure is to a first member including a first surface, a second surface provided on the opposite side to the first surface in a thickness direction, and an internal electrode disposed between the first surface and the second surface; a terminal connected to the internal electrode and extending from the second surface in the thickness direction; a second member including a third surface, a fourth surface provided on an opposite side to the third surface, and a through hole penetrating the third surface and the fourth surface and into which the terminal is disposed; a bonding layer disposed between the second surface of the first member and the third surface of the second member, bonding the first member and the second member; A holding device for holding an object on the first surface of the first member, a bonding layer through hole communicating with the through hole is formed in the bonding layer; The present invention is characterized in that an annular protrusion protruding from the second surface at least into the bonding layer through hole is formed integrally with the first member around the terminal.

[0008] In this holding device, an annular protrusion integrally formed on the second surface of the first member is disposed so as to protrude into at least the bonding layer through hole. That is, the annular protrusion is disposed so as to cover at least a part of the bonding layer from the second surface. Therefore, the creepage distance between the terminal and the bonding layer (in the case of a metal bonding material) or the second member (in the case of a metal) is increased, and therefore the insulation between the terminal and the bonding layer (in the case of a metal bonding material) or the second member (in the case of a metal) can be improved.

[0009] In the above-mentioned holding device, The bonding layer is preferably formed from a bonding material containing a metal material as a main component.

[0010] In this way, when the bonding layer is made of a bonding material (metal bonding material) whose main component is a metal material, the creepage distance between the terminal and the bonding layer is the shortest, making it easier for abnormal discharge to occur between the terminal and the bonding layer.

[0011] Therefore, by arranging the convex portion integrally formed on the second surface of the first member so as to cover at least a portion of the bonding layer, the creepage distance between the terminal and the bonding layer formed from the metal bonding material is increased, thereby improving the insulation between the terminal and the bonding layer formed from the metal bonding material.

[0012] In the above-mentioned holding device, a recess in which the terminal is disposed is formed on the second surface, It is preferable that the protrusion is formed so that the side surface of the recess and the inner peripheral surface of the protrusion are flush with each other.

[0013] Here, since heat is not transferred between the through hole of the second member and the recess of the first member via the bonding layer, a temperature difference is likely to occur in the vicinity directly above the through hole of the second member and the recess of the first member compared to other portions on the first surface, and therefore the vicinity directly above the through hole of the second member and the recess of the first member are likely to become temperature singular points.

[0014] Therefore, by providing a convex portion in this manner, the size (diameter) of the concave portion and the through hole can be made smaller than in the case where a convex portion is provided within a concave portion, thereby reducing areas that are prone to temperature singularities and improving thermal uniformity on the first surface.

[0015] In the above-mentioned holding device, It is preferable that a gap is formed between the protrusion and the through hole.

[0016] If there is a difference in thermal expansion between the material forming the first member and the material forming the second member, when the temperature of the holding device rises / falls, the difference in thermal expansion may cause the convex portion to come into contact with the second member, resulting in damage to the convex portion.

[0017] Therefore, by forming a gap between the protrusion and the second through hole, damage to the protrusion can be reliably prevented, and as a result, the protrusion can improve insulation between the terminal and the bonding layer (in the case of a metal bonding material) or the second member (in the case of a metal material).

[0018] Alternatively, in the above-mentioned holding device, The protrusion and the bonding layer may be in contact with each other.

[0019] Here, because heat is not transferred between the through hole of the second member and the first member via the bonding layer, a temperature difference is likely to occur in the vicinity directly above the through hole of the second member compared to other portions of the first surface, and therefore the vicinity directly above the through hole of the second member is likely to become a temperature singularity.

[0020] Therefore, by bringing the protrusion into contact with the bonding layer, heat transfer between the first member and the second member occurs via the bonding layer and the protrusion, and therefore heat transfer between the first member and the second member is promoted in the vicinity of the through hole of the second member, and therefore it is possible to suppress the occurrence of temperature singularities in the vicinity of directly above the through hole of the second member on the first surface. Effect of the Invention

[0021] According to the present disclosure, it is possible to provide a holding device capable of improving insulation properties. [Brief description of the drawings]

[0022] [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] 2 is a schematic configuration diagram of an XZ cross section near a terminal hole in the electrostatic chuck according to the embodiment. FIG. [Diagram 5] 2 is a schematic configuration diagram of an XZ cross section near a terminal hole in the electrostatic chuck of the first embodiment. FIG. [Figure 6] FIG. 11 is a schematic configuration diagram of an XZ cross section near a terminal hole in an electrostatic chuck according to a second embodiment. [Figure 7] FIG. 11 is a schematic configuration diagram of an XZ cross section near a terminal hole in an electrostatic chuck according to a third embodiment. [Figure 8] 13 is a schematic configuration diagram of an XZ cross section near a terminal hole showing a modified example. FIG. [Figure 9] 13 is a schematic configuration diagram of an XZ cross section near a terminal hole showing a modified example. FIG. [Figure 10] 13 is a schematic configuration diagram of an XZ cross section near a terminal hole showing a modified example. FIG. [Figure 11] 13 is a schematic configuration diagram of an XZ cross section near a terminal hole showing a modified example. FIG. [Figure 12] 13 is a schematic configuration diagram of an electrostatic chuck taken along an XZ cross section showing a modified example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] A holding device according to an embodiment of the present disclosure will be described in detail with reference to the drawings. In this embodiment, the holding device will be described by taking as an example an electrostatic chuck used in a semiconductor manufacturing device such as a film forming device (such as a CVD film forming device or a sputtering film forming device) or an etching device (such as a plasma etching device).

[0024] Therefore, an electrostatic chuck 1 according to the present embodiment will be described with reference to Figs. 1 to 4. The electrostatic chuck 1 according to the present embodiment is a device that attracts and holds a semiconductor wafer W (object) by electrostatic attraction, and is used, for example, to fix the semiconductor wafer W in a vacuum chamber of a semiconductor manufacturing device. As shown in Fig. 1, the electrostatic chuck 1 has a plate-shaped member 10, a base member 20, and a bonding layer 40 that bonds the plate-shaped member 10 and the base member 20. The plate-shaped member 10 is an example of a "first member" in the present disclosure, and the base member 20 is an example of a "second member" in the present disclosure.

[0025] In the following description, for convenience of explanation, the X, Y and Z axes are defined as shown in Fig. 1. Here, the Z axis is an axis in the axial direction of the electrostatic chuck 1 (the vertical direction in Fig. 1), and the X and Y axes are axes in the radial directions of the electrostatic chuck 1.

[0026] As shown in Fig. 1, the plate-like member 10 is a disk-shaped member and is made of ceramics. Various ceramics are used as the ceramics, but from the viewpoints of strength, wear resistance, plasma resistance, and the like, it is preferable to use ceramics mainly composed of 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). The diameter of the plate-like member 10 is, for example, about 150 to 350 mm, and the thickness of the plate-like member 10 is, for example, about 2 to 6 mm.

[0027] 1 and 2, the plate-shaped member 10 has a holding surface 11 for holding a semiconductor wafer W, and a bottom surface 12 provided on the opposite side to the holding surface 11 in the thickness direction of the plate-shaped member 10 (a direction that coincides with the Z-axis direction, the up-down direction). The semiconductor wafer W is held on the holding surface 11. Note that the holding surface 11 is an example of a "first surface" in the present disclosure, and the bottom surface 12 is an example of a "second surface" in the present disclosure.

[0028] The holding surface 11 of the plate-like member 10 has an uneven shape. Specifically, as shown in Figs. 2 and 3, a ring-shaped convex seal band 16 is formed near the outer edge of the holding surface 11, and a plurality of independent columnar convex portions 17 are formed inside the seal band 16. The cross section (XZ cross section) of the seal band 16 is substantially rectangular as shown in Fig. 2. The height (dimension in the Z-axis direction) of the seal band 16 is, for example, about 10 µm to 20 µm. The width (dimension in the X-axis direction) of the seal band 16 is, for example, about 0.5 mm to 5.0 mm.

[0029] As shown in Fig. 3, each of the protrusions 17 has a substantially circular shape when viewed in the Z-axis direction (plan view), and is disposed at substantially equal intervals. The shape of the cross section (XZ cross section) of each of the protrusions 17 is substantially rectangular, as shown in Fig. 2. The height of the protrusions 17 is substantially the same as the height of the seal band 16, and is, for example, about 10 to 20 µm. The width of the protrusions 17 (maximum diameter of the protrusions 17 when viewed in the Z-axis direction) is, for example, about 0.5 to 1.5 mm. The portions of the holding surface 11 of the plate-like member 10 on the inner side of the seal band 16 where the protrusions 17 are not formed are recesses 18.

[0030] The semiconductor wafer W is supported by the seal band 16 and the multiple protrusions 17 on the holding surface 11 of the plate-like member 10 and is held by the electrostatic chuck 1. When the semiconductor wafer W is held by the electrostatic chuck 1, a space S exists between the surface (lower surface) of the semiconductor wafer W and the holding surface 11 of the plate-like member 10 (more specifically, the recesses 18 of the holding surface 11) (see FIG. 2). An inert gas (e.g., helium gas) is supplied to this space S via a gas hole 30b penetrating the electrostatic chuck 1.

[0031] 2, the plate-like member 10 includes a chuck electrode 50 therein. The chuck electrode 50 has, for example, a substantially circular shape when viewed in the Z-axis direction, and is made of a conductive material (for example, tungsten, molybdenum, etc.). The chuck electrode 50 is an example of an "internal electrode" in the present disclosure. A via 61 is connected to the chuck electrode 50. The via 61 is disposed so as to extend in the Z-axis direction from the chuck electrode 50 toward the lower surface 12.

[0032] A bottomed hole 15 is formed on the lower surface 12 of the plate-like member 10. This bottomed hole 15 is a circular recess, and when viewed in the Z-axis direction, an area overlapping with a through hole 25 of the base member 20 described later is recessed toward the holding surface 11. The diameter of the bottomed hole 15 is, for example, 7 to 8 mm. A terminal pad 60 is disposed on a bottom 15b of the bottomed hole 15. When viewed in the Z-axis direction, the shape of the terminal pad 60 is, for example, substantially circular. The bottomed hole 15 is an example of a "recess" in the present disclosure.

[0033] The other end of the via 61 connected to the chuck electrode 50 is connected to the upper surface of the terminal pad 60. Thus, the terminal pad 60 is electrically connected to the chuck electrode 50 through the via 61. The terminal pad 60 and the via 61 are formed of a conductive material (for example, tungsten, molybdenum, etc.). In this embodiment, the terminal pad 60 is exposed from the plate-shaped member 10 in the thickness direction (Z-axis direction) as shown in FIG. 2, but as long as the lower surface of the terminal pad 60 is exposed from the plate-shaped member 10, a part or the entirety of the terminal pad 60 in the thickness direction may be embedded in the plate-shaped member 10. A power supply terminal 62 for connecting to an external power source is joined (brazed) to the lower surface (exposed surface) of the terminal pad 60, and power is supplied from the external power source to the chuck electrode 50 through the power supply terminal 62, the terminal pad 60, and the via 61. The terminal pad 60 and the power supply terminal 62 are examples of the "terminal" in the present disclosure, and the outer periphery of the power supply terminal 62 is covered with an insulating member.

[0034] 2, an annular protrusion 34 is provided on the lower surface 12 of the plate-shaped member 10 around the terminal pad 60 and the power supply terminal 62 so as to surround the bottomed hole 15 and protrude in the Z-axis direction. The annular protrusion 34 is made of ceramics like the plate-shaped member 10 and is integrally formed with the plate-shaped member 10. That is, the annular protrusion 34 may be integrally formed with the plate-shaped member 10 by co-firing, or may be integrally formed with the plate-shaped member 10 by diffusion bonding. Alternatively, the annular protrusion 34 may be formed by machining such as polishing after a thick plate-shaped member 10 is manufactured (the part other than the part that will become the annular protrusion 34 is scraped off). The inner diameter of the annular protrusion 34 and the inner diameter of the bottomed hole 15 are the same diameter, and the annular protrusion 34 is coaxial with the bottomed hole 15. That is, the side surface of the bottomed hole 15 and the inner peripheral surface of the annular protrusion 34 are flush with each other.

[0035] By doing so, the size (diameter) of the bottomed hole 15 and the through hole 25 can be made smaller than when the annular convex portion 34 is provided inside the bottomed hole 15. Here, since the through hole 25 of the base member 20 and the bottomed hole 15 of the plate-like member 10 do not transfer heat via the bonding layer 40, a temperature difference is likely to occur in the vicinity directly above the through hole 25 and the bottomed hole 15 on the holding surface 11 compared to other parts, and the vicinity directly above the through hole 25 and the bottomed hole 15 is likely to become a temperature singular point. Therefore, by reducing the size (diameter) of the bottomed hole 15 and the through hole 25 in this manner, the area that is likely to become a temperature singular point can be reduced, and the thermal uniformity on the holding surface 11 can be improved.

[0036] Here, the annular protrusion 34 only needs to extend in the Z-axis direction so as to cover at least a part of the bonding layer 40. In other words, the tip of the annular protrusion 34 only needs to be disposed in a bonding layer through hole 45 of the bonding layer 40, which will be described later. In this embodiment, the annular protrusion 34 protrudes halfway into the through hole 25 of the base member 20 (about 1 / 5 of the depth of the hole). The length (dimension in the Z-axis direction) of the annular protrusion 34 is preferably, for example, 3 mm or more (the length at which the tip of the annular protrusion 34 is located in the through hole 25). This is because the annular protrusion 34 is disposed over the entire area of ​​the bonding layer through hole 45 so as to cover the bonding layer 40.

[0037] 1, the base member 20 is cylindrical, more specifically, a stepped cylindrical shape formed by stacking two cylinders of different diameters with a common central axis Ca, with the lower surface of the cylinder with the smaller diameter placed on the upper surface of the cylinder with the larger diameter. The base member 20 may be made of metal (e.g., aluminum, aluminum alloy, etc.) or may be made of a material other than metal (e.g., ceramics, etc.).

[0038] 1 and 2, the base member 20 has an upper surface 21 and a lower surface 22 provided on the opposite side to the upper surface 21 in the direction of the central axis Ca (see FIG. 2) of the base member 20 (plate-shaped member 10) (i.e., the Z-axis direction). The upper surface 21 is an example of a "third surface" in the present disclosure, and the lower surface 22 is an example of a "fourth surface" in the present disclosure.

[0039] The diameter of the base member 20 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 of the base member 20 (dimension in the Z-axis direction) is, for example, about 20 mm to 50 mm.

[0040] 2, the base member 20 is formed with a coolant flow path 23 for flowing a coolant (e.g., a fluorine-based inert liquid, water, etc.). The coolant flow path 23 is connected to a supply port and a discharge port (not shown) provided on the lower surface 22 of the base member 20, and the coolant supplied to the base member 20 from the supply port flows through the coolant flow path 23 and is discharged from the discharge port to the outside of the base member 20. In this way, the base member 20 is cooled by flowing the coolant through the coolant flow path 23 of the base member 20, and the plate-like member 10 is thereby cooled via the bonding layer 40.

[0041] The base member 20 has a cylindrical through-hole 25 formed therein, penetrating between the upper surface 21 and the lower surface 22 in the thickness direction (the Z-axis direction, the vertical direction in FIG. 2). The power supply terminal 62 and the annular protrusion 34 are disposed within the through-hole 25. A gap 35 (see FIG. 4) is formed between the annular protrusion 34 and the through-hole 25.

[0042] The bonding layer 40 is disposed between the lower surface 12 of the plate-shaped member 10 and the upper surface 21 of the base member 20, and bonds the plate-shaped member 10 to the base member 20. The lower surface 12 of the plate-shaped member 10 and the upper surface 21 of the base member 20 are thermally connected via the bonding layer 40. The thickness of the bonding layer 40 (the dimension in the Z-axis direction) is, for example, about 0.1 to 1.0 mm.

[0043] The bonding layer 40 is made of a resin adhesive such as a silicone resin, an acrylic resin, or an epoxy resin, or a metal bonding material mainly composed of a metal material. Generally, a resin adhesive is used as the bonding layer 40, but when the electrostatic chuck 1 is used at high temperatures (for example, 250°C or higher), a resin adhesive may cause bonding failure due to insufficient heat resistance, so a metal bonding material is used. As the metal bonding material, for example, a metal adhesive that uses metal powder or metal foil for bonding, a material composed of a metal mesh such as a metal fiber, a porous material, or a mesh structure and a brazing material, or a material composed of a plurality of columnar metal pieces and a brazing material, etc. can be used. As the metal adhesive, the metal mesh, or the metal pieces, titanium, nickel, aluminum, copper, brass, an alloy of these, stainless steel, etc. can be used.

[0044] 2, a bonding layer through hole 45 in which the annular protrusion 34 is disposed is formed in the bonding layer 40. That is, the cylindrical bonding layer through hole 45 is formed between the bottomed hole 15 and the through hole 25. The bonding layer through hole 45 is coaxial with the bottomed hole 15 and the through hole 25, and the bottomed hole 15, the bonding layer through hole 45, and the through hole 25 are arranged in series in the Z-axis direction (the axial direction of the electrostatic chuck 1), forming a terminal hole 65 in which the terminal pad 60 and the power supply terminal 62 are arranged.

[0045] Here, the configuration inside the terminal hole 65 will be described with reference to FIG. 4. As shown in FIG. 4, the terminal pad 60 and the power supply terminal 62 are arranged inside the terminal hole 65, and the annular protrusion 34 formed integrally with the plate-like member 10 is arranged around them. The annular protrusion 34 extends from the lower surface 12 of the plate-like member 10 toward the lower surface 22 side of the base member 20, and its tip is located inside the through hole 25 formed in the base member 20. In this embodiment, the annular protrusion 34 extends to a depth position of about 1 / 5 of the through hole 25. As a result, the inner circumferential surface of the bonding layer through hole 45 of the bonding layer 40 is covered by the annular protrusion 34. A gap 35 is formed between the annular protrusion 34 and the through hole 25.

[0046] 3, the electrostatic chuck 1 is provided with through holes penetrating the electrostatic chuck 1, such as lift pin insertion holes 30a in which lift pins for pushing up the semiconductor wafer W from above the holding surface 11 are disposed, and gas holes 30b for supplying an inert gas from the lower surface 22 side of the base member 20 to the space S formed in the recess 18. In the following description, the lift pin insertion holes 30a and the gas holes 30b may be simply referred to as "through holes 30."

[0047] As such an electrostatic chuck 1, the following three embodiments (first to third embodiments) can be given, which are different depending on the combination of materials for forming the base member 20 and the bonding layer 40.

[0048] <First Example> First, a first embodiment will be described. In the first embodiment, the base member 20 is made of ceramics, and the bonding layer 40 is made of a metal bonding material. That is, in the electrostatic chuck 1 of the first embodiment, as shown in FIG. 5, a ceramic plate-shaped member 10 and a ceramic base member 20a are bonded to each other by a bonding layer 40a made of a metal bonding material.

[0049] The electrostatic chuck 1 of the first embodiment is suitable for use at high temperatures (e.g., 250° C. or higher) where a resin adhesive has insufficient heat resistance and would cause poor bonding. In the first embodiment, the bonding layer 40a is made of a metal bonding material, so that the creepage distance to the terminal pad 60 is extremely small.

[0050] Here, when used at high temperatures, it is difficult to place an insulating tube around the terminal and bond the insulating tube to the electrostatic chuck with a resin adhesive, as in the case of conventional electrostatic chucks, and the insulation property is reduced. This is because the resin adhesive deteriorates at high temperatures, causing gaps in the bonded portion or damage to the adhesive itself, and the gaps or damaged portions become leak paths. If a leak path is created, the insulation between the terminal pad 60 and the bonding layer 40a is destroyed, causing abnormal discharge.

[0051] Therefore, in the electrostatic chuck 1 of the first embodiment, an annular protrusion 34 is provided on the lower surface 12 of the plate-shaped member 10, which is integrally formed with the terminal plate-shaped member 10 so as to surround the opening (terminal pad 60) of the bottomed hole 15. The annular protrusion 34 is provided to a depth position of about 1 / 5 of the through hole 25, and completely covers the bonding layer 40a. Therefore, the annular protrusion 34 can lengthen the creepage distance between the terminal pad 60 and the bonding layer 40a. This improves the withstand voltage between the terminal pad 60 and the bonding layer 40a, and therefore improves the insulation between the terminal pad 60 and the bonding layer 40a.

[0052] In the electrostatic chuck 1 of the first embodiment, the gap 35 is provided between the annular protrusion 34 and the through hole 25, so that the creepage distance between the terminal pad 60 and the bonding layer 40a can be further increased. This can further improve the insulation between the terminal pad 60 and the bonding layer 40a. Since there is almost no difference in thermal expansion between the plate-like member 10 and the base member 20b, for example, about 0.5 mm (a clearance required during manufacturing) is sufficient as the gap 35.

[0053] <Second Example> Next, a second embodiment will be described. In the second embodiment, the base member 20 is made of metal, and the bonding layer 40 is made of a metal bonding material. That is, in the electrostatic chuck 1 of the second embodiment, as shown in FIG. 6, a ceramic plate-shaped member 10 and a metal base member 20b are bonded to each other by a bonding layer 40a made of a metal bonding material.

[0054] The electrostatic chuck 1 of the second embodiment is also suitable for use at high temperatures (e.g., 250° C. or higher) where the heat resistance of a resin adhesive is insufficient, similar to the first embodiment. Also in the second embodiment, the bonding layer 40a made of a metal bonding material is used, so that the creepage distance to the terminal pad 60 is very small.

[0055] However, in the electrostatic chuck 1 of the second embodiment, an annular protrusion 34 is provided on the lower surface 12 of the plate-shaped member 10, which is integrally formed with the plate-shaped member 10 so as to surround the opening of the bottomed hole 15. Therefore, the annular protrusion 34 can lengthen the creepage distance between the terminal pad 60 and the bonding layer 40a. This improves the withstand voltage between the terminal pad 60 and the bonding layer 40a, making it possible to prevent the occurrence of abnormal discharge between the terminal pad 60 and the bonding layer 40a. In the second embodiment, the length (dimension in the Z-axis direction) of the annular protrusion 34 is the same as that of the first embodiment.

[0056] In the electrostatic chuck 1 of the second embodiment, since there is a difference in thermal expansion between the plate-like member 10 and the base member 20b, when the temperature rises / falls during use of the electrostatic chuck 1, the difference in thermal expansion causes the annular protrusion 34 to come into contact with the base member 20b, which may damage the annular protrusion 34 and cause the damaged portion to become a leak path.

[0057] For this reason, a gap 35 is formed between the annular protrusion 34 and the through hole 25. The gap 35 is set to be larger than that in the first embodiment and to a degree (e.g., about 0.5 mm) that prevents the annular protrusion 34 from contacting the base member 20b even due to the difference in thermal expansion between the plate-like member 10 and the base member 20b. By providing such a gap 35, damage to the annular protrusion 34 can be reliably prevented. As a result, the annular protrusion 34 can ensure insulation between the terminal pad 60 and the base member 20b.

[0058] <Third Example> Finally, a third embodiment will be described. In the third embodiment, the base member 20 is made of metal, and the bonding layer 40 is made of a resin adhesive. That is, in the electrostatic chuck 1 of the third embodiment, as shown in FIG. 7, a ceramic plate-shaped member 10 and a metal base member 20b are bonded to each other by a bonding layer 40b made of a resin adhesive.

[0059] In the electrostatic chuck 1 of the third embodiment, it is necessary to ensure insulation between the terminal pad 60 and the base member 20a. For this reason, in a conventional electrostatic chuck, an insulating tube is disposed around the terminal, and the insulating tube is bonded to the electrostatic chuck with a resin adhesive. However, even if the electrostatic chuck is not used at high temperatures, the temperature of the electrostatic chuck rises and falls during use, and the resin adhesive deteriorates due to the temperature change, and there is a risk that a gap will be formed in the bonded portion or the adhesive itself will be damaged. Then, the gap or damaged portion will become a leak path, and the insulation between the terminal and the base member will be destroyed, causing an abnormal discharge.

[0060] Therefore, also in the electrostatic chuck 1 of the third embodiment, an annular protrusion 34 is provided on the lower surface 12 of the plate-shaped member 10, which is integrally formed with the plate-shaped member 10 so as to surround the opening of the bottomed hole 15. This makes it possible to lengthen the creepage distance between the terminal pad 60 and the base member 20b by the annular protrusion 34. This improves the withstand voltage between the terminal pad 60 and the base member 20b, thereby improving the insulation between the terminal pad 60 and the base member 20b.

[0061] Also, in the third embodiment, as in the second embodiment, since there is a difference in thermal expansion between the plate-like member 10 and the base member 20b, a gap 35 of the same size as in the second embodiment (for example, about 0.5 mm) is provided between the annular protrusion 34 and the through hole 25. This can reliably prevent damage to the annular protrusion 34, and the annular protrusion 34 can ensure insulation between the terminal pad 60 and the base member 20b.

[0062] <Modification> Next, a modified example will be described with reference to Fig. 8. The modified example has the same basic structure as the above-described embodiment, but the diameter of the bonding layer through hole 45 of the bonding layer 40 is smaller than that of the above-described embodiment. That is, in the modified example, as shown in Fig. 8, (the outer peripheral surface of) the annular protrusion 34 and the bonding layer 40 (the inner peripheral surface of the bonding layer through hole 45) are in contact with each other.

[0063] Here, heat is not transferred between the bottomed holes 15 and the base member 20 via the bonding layer 40. Therefore, the temperature difference in the vicinity of the bottomed holes 15 on the holding surface 11 of the plate-like member 10 becomes large compared to other portions, and the vicinity is likely to become a temperature singularity.

[0064] Therefore, by bringing the annular protrusion 34 that protrudes so as to surround the opening of the bottomed hole 15 into contact with the bonding layer 40, heat transfer between the plate-like member 10 and the base member 20 occurs via the bonding layer 40 and the annular protrusion 34. This promotes heat transfer in the vicinity of the bottomed hole 15. Therefore, it is possible to suppress the occurrence of temperature singularities in the vicinity of the bottomed hole 15 on the holding surface 11, and it is possible to ensure thermal uniformity on the holding surface 11.

[0065] As described above, according to the electrostatic chuck 1 of the present embodiment, the annular protrusion 34 formed integrally with the plate-shaped member 10 is provided on the lower surface 12 of the plate-shaped member 10 so as to surround the terminal pad 60 and the power supply terminal 62 around the bottomed hole 15 and cover the bonding layer 40. Therefore, the annular protrusion 34 can increase the creepage distance between the terminal pad 60 and the bonding layer 40a (Examples 1 and 2) or the base member 20b (Examples 1 and 3).

[0066] This makes it possible to prevent abnormal discharge from occurring between the terminal pad 60 and the bonding layer 40a (Examples 1 and 2) or between the terminal pad 60 and the base member 20b (Examples 1 and 3). Therefore, the insulation around the terminal of the electrostatic chuck 1 can be improved.

[0067] 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 50 is exemplified as the internal electrode, but the internal electrode is not limited to the chuck electrode 50 and may be a high-frequency electrode or a heater electrode. However, it is preferable to apply the present disclosure to a terminal portion connected to the chuck electrode 50 to which the highest voltage is applied among the internal electrodes.

[0068] In the above embodiment, the terminal pad 60 is directly connected to the chuck electrode 50 (internal electrode) by the via 61, but the terminal pad 60 and the chuck electrode 50 (internal electrode) may be electrically connected to each other via a connection pad 66 as shown in Fig. 9. Specifically, the terminal pad 60 and the connection pad 66 may be connected to each other by a via 61a, and the connection pad 66 and the chuck electrode 50 may be connected to each other by a via 61b, thereby electrically connecting the terminal pad 60 to the chuck electrode 50 (internal electrode).

[0069] In the above embodiment, the annular protrusion 34 is provided halfway through the through hole 25. However, as shown in FIG. 10, the annular protrusion 34 may be provided over the entire area of ​​the through hole 25 (so as not to protrude from the base member 20 up to the lower surface 22 of the base member 20). This makes it possible to improve the insulation around the terminal of the electrostatic chuck 1 without providing an insulating member on the outer periphery of the power supply terminal 62. If the annular protrusion 34 is provided over the entire area of ​​the through hole 25, the annular protrusion 34 becomes long, and there is a risk of damaging the annular protrusion 34 during the manufacture of the electrostatic chuck 1. Therefore, instead of providing the annular protrusion 34 over the entire area of ​​the through hole 25, as shown in FIG. 11, an insulating sleeve 36 made of a different member may be joined to the annular protrusion 34 provided halfway through the through hole 25. This makes it possible to improve the insulation around the terminal of the electrostatic chuck 1 while preventing the annular protrusion 34 from being damaged during the manufacture.

[0070] In addition, the above embodiment illustrates a case where the annular convex portion 34 extends to the base member 20 (inside the second through hole), but the above effect can also be obtained even if the annular convex portion 34 extends halfway through the bonding layer 40, that is, the tip of the annular convex portion 34 is located within the bonding layer through hole 45.

[0071] In addition, the tip corner of the annular protrusion 34 may be rounded or tapered, or a step may be provided in the annular protrusion 34 (the thickness of the annular protrusion 34 may be changed). This makes it possible to further increase the creepage distance between the terminal pad 60 and the bonding layer 40a or base member 20b made of metal.

[0072] Furthermore, in the above embodiment, the case where the annular protrusion 34 is provided in the terminal hole 65 has been described, but as shown in Fig. 12, the annular protrusion 34 may also be provided in the through-holes 30 such as the lift pin insertion hole 30a and the gas hole 30b. This can improve the insulation between the semiconductor wafer W and the bonding layer 40a or the base member 20b made of metal. [Explanation of symbols]

[0073] 1. Electrostatic chuck 10 Plate-shaped member 11 Holding surface 12 Bottom side 15 Bottomed hole 20 Base material 21 Top side 22 Bottom side 25 Through hole 30 Through hole 34 Annular protrusion 35 Gap 40 Bonding layer 45 Bonding layer through hole 50 Chuck electrode 60 Terminal Pad 62 Power supply terminal W Semiconductor wafer

Claims

1. a first member including a first surface, a second surface provided on an opposite side to the first surface, and an internal electrode disposed between the first surface and the second surface; a terminal connected to the internal electrode and disposed on the second surface; a second member including a third surface, a fourth surface provided on an opposite side to the third surface, and a through hole penetrating the third surface and the fourth surface and into which the terminal is disposed; a bonding layer disposed between the second surface of the first member and the third surface of the second member, bonding the first member and the second member; A holding device for holding an object on the first surface of the first member, a bonding layer through hole communicating with the through hole is formed in the bonding layer; a ring-shaped protrusion protruding from the second surface at least into the bonding layer through hole is formed integrally with the first member around the terminal; A gap is formed between the protrusion and the through hole, In the through hole, a ring-shaped insulating sleeve is formed at a tip of the protrusion, the sleeve extending to the fourth surface, A gap is formed between the sleeve and the through hole. A holding device characterized in that

2. 2. The holding device according to claim 1, The bonding layer is formed of a bonding material containing a metal material as a main component. A holding device characterized in that

3. The holding device according to claim 1 or 2, a recess in which the terminal is disposed is formed on the second surface, The protrusion is formed so that the side surface of the recess and the inner peripheral surface of the protrusion are flush with each other. A holding device characterized in that

4. In any one of the holding devices according to claims 1 to 3, The protrusion and the bonding layer are in contact with each other. A holding device characterized in that

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