Holding device

Abstract

To provide a holding device which allows improvement in insulation quality.SOLUTION: An electrostatic chuck 1 for holding a semiconductor wafer W on a holding surface 11 of a plate-like member 10 comprises: the plate-like member 10 having the holding surface 11, a lower surface 12 provided on the opposite side to the holding surface 11, and a bottomed hole 15 opened on the lower surface 12; a base member 20 which has a through-hole 25 communicating with the bottomed hole 15 and is bonded to the lower surface 12 side of the plate-like member 10; and an annular insulation sleeve 30 disposed around the through-hole 25. An inner circumferential surface 15a of the bottomed hole 15 is provided with a female screw part 16, and an outer circumferential surface 30a of the insulation sleeve 30 is provided with a male screw part 36 to be screwed to the female screw part 16.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] A known holding device is, for example, an electrostatic chuck described in Patent Document 1. This electrostatic chuck includes a ceramic plate (plate-shaped member) that holds an object on its surface (holding surface) and a metal base member (metal part) bonded to the ceramic plate, and internal electrodes such as a chuck electrode and a heater electrode are disposed inside the ceramic plate. This electrostatic chuck also includes a configuration for supplying power to the internal electrodes.

[0003] That is, a terminal through hole is formed inside the base member, opening on the surface of the base member facing the ceramic plate (hereinafter referred to as the "upper surface"), and a columnar electrode terminal is disposed inside the terminal through hole. Also, an electrode pad that is conductive to the internal electrode is disposed in a predetermined region of the surface of the ceramic plate facing the base member (hereinafter referred to as the "lower surface"). Then, to ensure insulation between the electrode terminal and the metal base member, an insulating member that continuously surrounds the electrode terminal is disposed inside the terminal through hole of the base member so as to be interposed between the electrode terminal and the surface of the terminal through hole, and the insulating member is fixed to the ceramic plate with an adhesive. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-258615 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in recent years, the electrostatic chuck has been increasingly used at high voltages, which may result in an insufficient insulation distance, a decrease in insulation properties, and the risk of dielectric breakdown. Furthermore, since the portion of the holding surface directly above the terminal through hole of the base member where the insulating member is disposed becomes a temperature singular point, there is a trend toward smaller diameter terminal through holes in order to improve thermal uniformity on the holding surface, and higher insulation properties are required.

[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] In order to solve the above problems, one aspect of the present disclosure is to a plate-like member including a first surface, a second surface provided on the opposite side of the first surface, and a hole opening in the second surface; a metal portion having a through hole communicating with the hole and joined to the second surface side of the plate-like member; an annular insulating member disposed in the through hole, A holding device for holding an object on the first surface of the plate-like member, A first screw portion is formed on the inner circumferential surface of the hole, The insulating member is characterized in that a second screw portion that screws into the first screw portion is formed on the outer circumferential surface thereof.

[0008] In this holding device, a first threaded portion is formed on the inner peripheral surface of the hole, and a second threaded portion that screws into the first threaded portion is formed on the outer peripheral surface of the insulating member. Therefore, by screwing the second threaded portion into the first threaded portion, the insulating member can be fixed to the plate-like member. This results in a zigzag, rather than a straight, dielectric breakdown path in the assembly portion (threaded portion) of the plate-like member (hole) and the insulating member, thereby lengthening the insulation distance. Furthermore, because only the first threaded portion is formed in the bottomed hole, the diameter of the through hole that communicates with the bottomed hole remains almost unchanged. Therefore, the insulation properties of the holding device can be improved without changing the diameter of the through hole.

[0009] In the above-mentioned holding device, It is preferable that an adhesive be filled between the first screw portion and the second screw portion.

[0010] By filling the threaded portion where the first threaded portion and the second threaded portion are screwed together with adhesive in this manner, the insulation properties of the threaded portion can be further improved and the joining strength of the threaded portion can be improved.

[0011] In any of the above-mentioned holding devices, there is a difference between the thermal expansion coefficient of a material forming the plate-like member and the thermal expansion coefficient of a material forming the metal portion, It is preferable that a gap is formed between the insulating member and the through hole.

[0012] If there is a difference in thermal expansion between the plate-shaped member and the metal part, when the temperature of the holding device rises or falls, the difference in thermal expansion will cause a difference in the amount of deformation between the plate-shaped member and the metal part. As a result, if the insulating member comes into contact with the metal part, the insulating member may be damaged and its insulation properties may be reduced.

[0013] Therefore, by providing a gap between the insulating member and the through hole, damage to the insulating member caused by the difference in thermal expansion can be reliably prevented, thereby avoiding a decrease in insulation performance due to damage to the insulating member caused by the difference in thermal expansion. [Effects of the Invention]

[0014] According to the present disclosure, it is possible to provide a holding device that can improve insulation properties. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic perspective view of an electrostatic chuck according to a first embodiment. [Figure 2] 1 is a schematic configuration diagram of an XZ cross section of an electrostatic chuck according to a first embodiment. [Figure 3]FIG. 3 is an enlarged view of part A shown in FIG. 2. [Figure 4] FIG. 10 is a schematic diagram of the XZ cross section near a joint portion (screw portion) in the electrostatic chuck of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] 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 semiconductor manufacturing equipment such as a film forming apparatus (such as a CVD film forming apparatus or a sputtering film forming apparatus) or an etching apparatus (such as a plasma etching apparatus).

[0017] 1 to 3, an electrostatic chuck 1 according to the present embodiment will be described. 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 includes a plate-like member 10, a base member 20, and a bonding layer 40 that bonds the plate-like member 10 and the base member 20 together.

[0018] 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 direction of the electrostatic chuck 1.

[0019] As shown in Fig. 1, the plate-shaped member 10 is a circular member made of ceramics. Various ceramics can be used, 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 term "main component" here refers to the component with the highest content (for example, a component with a volume content of 90 vol% or more). The diameter of the plate-shaped member 10 is, for example, about 150 mm to 350 mm, and the thickness of the plate-shaped member 10 is, for example, about 2 mm to 6 mm.

[0020] 1 and 2, the plate-shaped member 10 has a holding surface 11 that holds a semiconductor wafer W, and a bottom surface 12 that is provided on the opposite side of 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 this 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.

[0021] 2, the plate-shaped member 10 has 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 or molybdenum). A via 61 is connected to the chuck electrode 50. The via 61 is arranged to extend from the chuck electrode 50 toward the lower surface 12 in the Z-axis direction.

[0022] A bottomed hole 15 is formed in the lower surface 12 of the plate-like member 10. This bottomed hole 15 is a circular recess that opens toward the lower surface 12, and when viewed in the Z-axis direction, an area that overlaps 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 mm to 8 mm. A female screw portion 16 is formed on an inner circumferential surface 15a of the bottomed hole 15 (see FIG. 3). A terminal pad 60 is disposed on a bottom surface 15b of the bottomed hole 15. When viewed in the Z-axis direction, the shape of the terminal pad 60 is, for example, approximately circular. The bottomed hole 15 is an example of a "hole" in the present disclosure, and the female screw portion 16 is an example of a "first screw portion" in the present disclosure.

[0023] The other end of the via 61 connected to the chuck electrode 50 is connected to the upper surface of the terminal pad 60. As a result, 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 (e.g., tungsten, molybdenum, etc.). In this embodiment, as shown in FIG. 2 , the entire terminal pad 60 is exposed from the plate-shaped member 10 in the thickness direction (Z-axis direction). However, as long as the lower surface of the terminal pad 60 is exposed from the plate-shaped member 10, a part or the entire terminal pad 60 in the thickness direction may be embedded in the plate-shaped member 10. A power supply terminal 62 for connection to an external power source is joined (brazed) to the lower surface (exposed surface) of the terminal pad 60. Power is supplied from the external power source to the chuck electrode 50 via the power supply terminal 62, the terminal pad 60, and the via 61.

[0024] 1, the base member 20 is cylindrical, more specifically, a stepped cylindrical shape formed by stacking two cylinders of different diameters on top of each other with a common central axis, with the lower surface of the smaller diameter cylinder placed on the upper surface of the larger diameter cylinder. The base member 20 is made of metal (e.g., aluminum, aluminum alloy, etc.). The base member 20 is an example of a "metal part" in the present disclosure.

[0025] 1 and 2, the base member 20 has an upper surface 21 and a lower surface 22 provided on the opposite side of the upper surface 21 in 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.

[0026] The diameter of the upper portion of the base member 20 is, for example, about 150 mm to 300 mm, and the diameter of the lower portion is, for example, about 180 mm to 350 mm. The thickness of the base member 20 (dimension in the Z-axis direction) is, for example, about 20 mm to 50 mm.

[0027] In addition, a refrigerant flow path is formed in the base member 20 for flowing a refrigerant (e.g., a fluorine-based inert liquid, water, etc.), and by flowing the refrigerant in the refrigerant flow path, the base member 20 is cooled, and thereby the plate-like member 10 is cooled via the bonding layer 40.

[0028] 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). A power supply terminal 62 and an insulating sleeve 30 are disposed within this through-hole 25. The insulating sleeve 30 is an annular member disposed so as to cover the power supply terminal 62, and the end portion on the bottomed hole 15 side is fixed to the plate-like member 10. Details of the insulating sleeve 30 and its fixing structure will be described later.

[0029] 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 (dimension in the Z-axis direction) is, for example, about 0.1 mm to 1.0 mm.

[0030] The bonding layer 40 is made of a resin adhesive such as a silicone-based resin, an acrylic-based resin, or an epoxy-based resin. As shown in Fig. 2, the bonding layer 40 has a through hole 45 formed therein in which the insulating sleeve 30 is disposed. That is, the cylindrical through hole 45 is formed between the bottomed hole 15 and the through hole 25. The through hole 45 is coaxial with the bottomed hole 15 and the through hole 25, and the bottomed hole 15, the 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), thereby forming a terminal hole 65 in which a terminal pad 60 and a power supply terminal 62 are disposed.

[0031] The configuration inside the terminal hole 65 will now be described with reference to Figures 2 and 3. As shown in Figure 2, a terminal pad 60 and a power supply terminal 62 are arranged inside the terminal hole 65, and an insulating sleeve 30 is arranged around these. The insulating sleeve 30 is fixed to the plate-like member 10 on the bottomed hole 15 side, and its tip (the side opposite the fixed end) is located on the lower surface 22 of the base member 20. In other words, the insulating sleeve 30 extends to the lower surface 22 of the base member 20 and is arranged over the entire area of ​​the through hole 25. A certain gap S is formed between the insulating sleeve 30 and the through hole 25.

[0032] The insulating sleeve 30 is made of ceramics, similar to the plate-shaped member 10, and as shown in Fig. 3, has a male thread portion 36 that screws into the female thread portion 16 formed on the inner circumferential surface 15a of the bottomed hole 15. The male thread portion 36 is formed on the end of the outer circumferential surface 30a of the insulating sleeve 30 that is positioned in the bottomed hole 15. As a result, when the insulating sleeve 30 is inserted into the bottomed hole 15 while being rotated, the male thread portion 36 of the insulating sleeve 30 screws into the female thread portion 16 of the bottomed hole 15, and the insulating sleeve 30 is screw-fixed to the plate-shaped member 10. The male thread portion 36 is an example of a "second screw portion" in the present disclosure.

[0033] An adhesive 70 is filled between the male thread portion 36 and the female thread portion 16. That is, before inserting the insulating sleeve 30 into the bottomed hole 15, the adhesive 70 before hardening is applied to at least one of the male thread portion 36 or the female thread portion 16, and after the insulating sleeve 30 is screwed to the plate-like member 10, the adhesive 70 is hardened. This allows the adhesive 70 to be filled in the joint portion between the insulating sleeve 30 and the plate-like member 10, i.e., the thread portion where the female thread portion 16 and the male thread portion 36 are screwed together.

[0034] As described above, in the electrostatic chuck 1 of this embodiment, the bottomed hole 15 of the plate-shaped member 10 has a female thread portion 16 formed therein, and the insulating sleeve 30 has a male thread portion 36 formed therein to thread onto the female thread portion 16. Therefore, by threading the male thread portion 36 onto the female thread portion 16, the insulating sleeve 30 can be fixed to the plate-shaped member 10. As a result, the dielectric breakdown path at the joint (thread portion) between the plate-shaped member 10 (bottomed hole 15) and the insulating sleeve 30 is formed in a zigzag pattern rather than a straight line, thereby increasing the insulation distance. Furthermore, since only the female thread portion 16 is formed in the bottomed hole 15, the diameter of the bottomed hole 15 remains almost unchanged, and therefore the diameter of the through hole 25 in the base member 20 that communicates with the bottomed hole 15 does not increase. Therefore, the insulation properties of the electrostatic chuck 1 can be improved without changing (enlarging) the diameter of the through hole 25.

[0035] Furthermore, in the electrostatic chuck 1 of this embodiment, the joining portion (threaded portion) where the female threaded portion 16 and the male threaded portion 36 are screwed together is filled with adhesive 70. This further improves the insulation properties of the joining portion (threaded portion) between the plate-like member 10 (bottomed hole 15) and the insulating sleeve 30, and also improves the joining strength of the joining portion (threaded portion).

[0036] In the electrostatic chuck 1 of this embodiment, there is a difference in thermal expansion between the plate-shaped member 10 and the base member 20, and therefore, when the temperature rises or falls, the difference in thermal expansion causes a difference in the amount of deformation between the plate-shaped member 10 and the base member 20. Therefore, when the insulating sleeve 30 fixed to the plate-shaped member 10 comes into contact with the base member 20, the insulating sleeve 30 may be damaged, resulting in a decrease in insulation properties.

[0037] For this reason, in the electrostatic chuck 1 of this embodiment, a gap S is provided between the insulating sleeve 30 and the through hole 25. This makes it possible to reliably prevent damage to the insulating sleeve 30 caused by the difference in thermal expansion between the plate-shaped member 10 and the base member 20 when the temperature of the electrostatic chuck 1 rises or falls. Therefore, it is possible to avoid a decrease in insulation properties due to damage to the insulating sleeve 30 caused by the difference in thermal expansion. Note that the gap S may be set to a size (for example, about 0.5 mm) that prevents the insulating sleeve 30 from coming into contact with the base member 20 when the base member 20 is thermally deformed.

[0038] The insulating sleeve 30 extends to the lower surface 22 of the base member 20 and is disposed over the entire area of ​​the through hole 25. As a result, the entire inner circumferential surface of the through hole 25 of the base member 20 is covered with the insulating sleeve 30, which further improves the insulation properties of the electrostatic chuck 1.

[0039] As described above, according to the electrostatic chuck 1 of the present embodiment, the bottomed hole 15 of the plate-shaped member 10 is provided with the female screw portion 16, the insulating sleeve 30 is provided with the male screw portion 36, and the male screw portion 36 is screwed into the female screw portion 16, thereby fixing the insulating sleeve 30 to the plate-shaped member 10. Therefore, the insulation distance at the joint portion (thread portion) between the plate-shaped member 10 (bottomed hole 15) and the insulating sleeve 30 can be increased, thereby improving the insulation properties.

[0040] [Second embodiment] Next, a second embodiment will be described. The second embodiment has the same basic configuration as the first embodiment, but differs in that the bonding layer is made of a metal bonding material whose main component is a metal material. Therefore, the same components as those in the first embodiment will be given the same reference numerals and their descriptions will be omitted as appropriate, and the description will focus on the differences from the first embodiment.

[0041] In the electrostatic chuck 1a of the second embodiment, as shown in FIG. 4, the plate-shaped member 10 and the base member 20 are bonded together by a bonding layer 40a made of a metal bonding material. The bonding layer 40a is an example of the “metal portion” of the present disclosure. Because the plate-shaped member 10 and the base member 20 are bonded together by the bonding layer 40a made of a metal bonding material, the electrostatic chuck 1a is suitable for use at high temperatures (e.g., 250°C or higher) where resin adhesives lack heat resistance. Examples of metal bonding materials that can be used include metal adhesives using metal powder or metal foil, materials made of metal fibers, porous materials, metal meshes (e.g., mesh structures) and brazing material, and materials made of multiple columnar metal pieces and brazing material. Metals that can be used to form the metal adhesives, metal meshes, or metal pieces include titanium, nickel, aluminum, copper, brass, alloys thereof, and stainless steel. Note that FIG. 4 illustrates the area surrounding the bonded portion of the insulating sleeve 30 in the electrostatic chuck 1 of the first embodiment (the area corresponding to area A in FIG. 2).

[0042] In the electrostatic chuck 1a of the second embodiment, as in the first embodiment, a female screw portion 16 is formed in the bottomed hole 15 of the plate-shaped member 10, a male screw portion 36 is formed in the insulating sleeve 30, and the male screw portion 36 is screwed into the female screw portion 16, thereby fixing the insulating sleeve 30 to the plate-shaped member 10. This increases the insulation distance at the joint (thread portion) between the plate-shaped member 10 (bottomed hole 15) and the insulating sleeve 30. Therefore, the insulation properties of the electrostatic chuck 1a can be improved without changing (enlarging) the diameter of the through hole 25.

[0043] An adhesive 70 is filled into the joint (threaded portion) where the female screw portion 16 and the male screw portion 36 are screwed together, thereby improving the joint strength and further improving the insulating properties.

[0044] Furthermore, gaps S are provided between the insulating sleeve 30 and the through hole 45 of the bonding layer 40a, and between the insulating sleeve 30 and the through hole 25 of the base member 20. This makes it possible to prevent damage to the insulating sleeve 30 caused by differences in thermal expansion between the plate-like member 10 and the bonding layer 40a and between the insulating sleeve 30 and the base member 20, thereby avoiding a decrease in insulation due to damage to the insulating sleeve 30 caused by differences in thermal expansion.

[0045] Thus, according to the electrostatic chuck 1a of the second embodiment, even when the plate-shaped member 10 and the base member 20 are joined with a joining layer 40a made of a metal joining material, the insulation can be improved without changing (enlarging) the diameter of the through hole 25.

[0046] The above-described 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-described embodiment, the terminal hole 65 is exemplified as the terminal hole of the chuck electrode 50, but the present disclosure is not limited to the chuck electrode 50, and can also be applied to terminal holes of a high-frequency electrode, a heater electrode, or the like.

[0047] Furthermore, in the above embodiment, the present disclosure has been exemplified as being applied to a case where the insulating sleeve 30 is disposed in the terminal hole 65, but the present disclosure can also be applied to a case where an insulating sleeve is disposed in a through-hole formed in the electrostatic chuck, such as a gas hole for supplying an inert gas to the holding surface 11 or a lift pin hole in which a lift pin is disposed, without being limited to a terminal hole. In other words, the "hole opening into the second surface" of the present disclosure is not limited to a bottomed hole exemplified in the above embodiment, but may also be a through-hole that penetrates a plate-like member. [Explanation of symbols]

[0048] 1. Electrostatic chuck 10 Plate-shaped member 11 Holding surface 12 Bottom side 15 Bottomed hole 16 Female thread 20 Base member 21 Top side 22 Bottom side 25 through holes 30 Insulating sleeve 36 Male thread 40 Bonding layer 70 Adhesive S Gap W Semiconductor wafer

Claims

1. a plate-like member including a first surface, a second surface provided on the opposite side of the first surface, and a hole opening in the second surface; a metal portion having a through hole communicating with the hole and joined to the second surface side of the plate-like member; an annular insulating member disposed in the through hole, A holding device for holding an object on the first surface of the plate-like member, A first threaded portion is formed on the inner circumferential surface of the hole, A second screw portion that screws into the first screw portion is formed on the outer circumferential surface of the insulating member. A holding device characterized by:

2. 2. The holding device according to claim 1, An adhesive is filled between the first screw portion and the second screw portion. A holding device characterized by:

3. The holding device according to claim 1 or 2, there is a difference between the thermal expansion coefficient of a material forming the plate-like member and the thermal expansion coefficient of a material forming the metal portion, A gap is formed between the insulating member and the through hole. A holding device characterized by:

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