Holding device

Abstract

To provide a holding device capable of preventing immersion of plasma and process gass to the vicinity of an outer peripheral surface of a bonding layer.SOLUTION: A holding device comprises: a plate-like member 10; a base member 20; and a bonding layer 40 that is arranged between the plate-like member 10 and the base member 20, and bonds the plate-like member 10 and the base member 20. An electrostatic chuck 1 that holds a semiconductor wafer W onto a holding surface 11 of the plate-like member 10 has: an inner side protection member 50 arranged so as to cover a whole area of an outer peripheral surface 40a of the bonding layer 40; and an outer side protection member 60 that is arranged at the outer side from the inner side protection member 50 and has a dimension in a Z-axis direction larger than that of the inner side protection member 50. The outer side protection member 60 is arranged so as to cover the whole area of the outer peripheral surface of the inner side protection member 50.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] A holding device is known that includes a first member that holds an object on a holding surface and a second member bonded to the first member via a bonding layer. In this type of holding device, measures are taken to protect the outer peripheral surface of the bonding layer because there is a risk of the bonding layer being deteriorated by plasma or process gas. For example, in a wafer support member (holding device) described in Patent Document 1, a recess is formed on the periphery of the adhesive layer (bonding layer), and an annular protective member is disposed in the recess so as to press against the wall surface, and the protective member prevents the plasma or process gas from penetrating into the adhesive layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-80389 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned holding device, there is a risk of a gap being generated between the protective member and the bonding layer due to the difference in thermal expansion coefficient between the protective member and the bonding layer. In addition, in order to improve the sealing performance of the protective member, it is necessary to use a material with high elasticity as the protective member, but since the protective member is also deteriorated by plasma or process gas, the elasticity of the protective member may decrease, and a gap may be generated between the protective member and the bonding layer. Furthermore, when the protective member is placed in the recess, the protective member may be twisted or tilted, and a gap may be generated between the protective member and the bonding layer. And when a gap is generated between the protective member and the bonding layer, plasma or process gas may enter the gap and deteriorate the bonding layer.

[0005] Therefore, the present disclosure has been made to solve the above-mentioned problems, and aims to provide a holding device that can prevent plasma or process gas from entering near the outer peripheral surface of the bonding layer. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the present disclosure is to A first member including a first surface and a second surface provided on an opposite side to the first surface in a first direction; a second member including a third surface and a fourth surface provided on an opposite side of the third surface in the first direction; 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, An inner protective member arranged to cover the entire outer circumferential surface of the bonding layer; an outer protective member disposed outside the inner protective member and having a dimension in the first direction larger than the inner protective member; The outer protective member is disposed so as to cover the entire outer peripheral surface of the inner protective member.

[0007] In this holding device, the outer protective member, which has a larger dimension in a first direction (thickness direction of the holding device) than the inner protective member, is arranged to cover the inner protective member, thereby preventing the inner protective member from twisting or tilting. This allows the inner protective member to reliably cover the entire outer peripheral surface of the bonding layer. Therefore, the inner protective member and the outer protective member can prevent plasma and process gas from entering near the outer peripheral surface of the bonding layer. Note that even if the inner protective member is arranged out of alignment, the outer protective member covers the inner protective member, so the outer protective member can prevent plasma and process gas from entering near the outer peripheral surface of the bonding layer.

[0008] In the above-mentioned holding device, a first step for disposing the inner protective member and a second step for disposing the outer protective member are formed on an outer periphery of the first member on the second surface side and an outer periphery of the second member on the third surface side, respectively; It is preferable that the inner protection member be in contact with both a side surface of the first step portion of the first member and a side surface of the first step portion of the second member.

[0009] In this way, the first step for arranging the inner protective member and the second step for arranging the outer protective member are provided on the outer periphery of the second surface side of the first member and the outer periphery of the third surface side of the second member, so that the inner protective member and the outer protective member can be arranged in the appropriate positions without being misaligned. At this time, since the bonding layer is securely sealed by the inner protective member, the outer protective member only needs to be in contact with at least one of the side surface of the first step portion of the first member and the side surface of the second member. As a result, the entire inner protective member in a state in which the entire outer periphery of the bonding layer is securely covered by the outer protective member can be securely covered by the outer protective member, so that the bonding layer can be securely sealed by the inner protective member, and the intrusion of plasma and process gas into the bonding layer can be prevented.

[0010] In the above-mentioned holding device, The outer protective member preferably has a higher elasticity than the inner protective member.

[0011] This allows the outer protective member to effectively press the inner protective member inward, improving the sealing performance of the inner protective member that seals the bonding layer, thereby effectively preventing the intrusion of plasma and process gas into the bonding layer.

[0012] In the above-mentioned holding device, It is preferable that the outer protective member presses the inner protective member inwardly in a second direction perpendicular to the first direction.

[0013] This reliably prevents the inner protective member from being partially twisted or tilted due to the difference in thermal expansion coefficient between the inner protective member and the bonding layer, and allows the outer protective member to more effectively press the inner protective member inward, thereby further improving the sealing performance of the inner protective member and more effectively preventing the intrusion of plasma and process gas into the bonding layer.

[0014] In the above-mentioned holding device, It is preferable that the outer circumferential surface of the inner protective member is formed in an arc shape that is convex outward in a second direction perpendicular to the first direction.

[0015] This allows the outer protective member to press the inner protective member inward more effectively, thereby further improving the sealing performance of the inner protective member, and thus more effectively preventing the intrusion of plasma and process gas into the bonding layer. Effect of the Invention

[0016] According to the present disclosure, it is possible to provide a holding device capable of preventing plasma or process gas from entering the vicinity of the outer peripheral surface of a bonding layer. [Brief description of the drawings]

[0017] [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] FIG. 2 is a schematic diagram of an enlarged XZ cross section near the outer periphery of a bonding layer. [Figure 4] 13 is a schematic configuration diagram of an enlarged XZ cross section near the outer periphery of a bonding layer in a modified example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] A holding device according to an embodiment of the present disclosure will be described in detail with reference to the drawings. In this embodiment, 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) will be described as an example.

[0019] An electrostatic chuck 1 according to the present embodiment will be described with reference to FIGS. 1 to 3. 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 FIGS. 1 and 2, the electrostatic chuck 1 includes a plate-shaped member 10, a base member 20, a bonding layer 40 that bonds the plate-shaped member 10 and the base member 20, an inner protective member 50, and an outer protective member 60. 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.

[0020] In the following description, for convenience of explanation, the XYZ 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. The Z axis direction is an example of a "first direction" in the present disclosure, and the X axis direction (Y axis direction) is an example of a "second direction" in the present disclosure.

[0021] As shown in Fig. 1, the plate-like member 10 is a disk-shaped member and is made of ceramics. Various ceramics can be used as the ceramics, 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).

[0022] The plate-shaped member 10 is composed of an outer peripheral portion 10a, which is a portion in which a notch is formed on the upper side along the outer periphery, and an inner portion 10b located inside the outer peripheral portion 10a. The thickness of the inner portion 10b of the plate-shaped member 10 (thickness in the Z-axis direction, the same applies below) is thicker than the thickness of the outer peripheral portion 10a by the amount of the notch formed in the outer peripheral portion 10a. In other words, the thickness of the plate-shaped member 10 changes at the boundary between the outer peripheral portion 10a and the inner portion 10b of the plate-shaped member 10.

[0023] The diameter of the inner portion 10b of the plate-shaped member 10 is, for example, about 50 mm to 500 mm (usually about 200 mm to 350 mm), and the diameter of the outer peripheral portion 10a of the plate-shaped member 10 is, for example, about 60 mm to 510 mm (usually about 210 mm to 360 mm) (however, the diameter of the outer peripheral portion 10a is larger than the diameter of the inner portion 10b). The thickness of the inner portion 10b of the plate-shaped member 10 is, for example, about 1 mm to 10 mm, and the thickness of the outer peripheral portion 10a of the plate-shaped member 10 is, for example, about 0.5 mm to 9.5 mm (however, the thickness of the outer peripheral portion 10a is thinner than the thickness of the inner portion 10b).

[0024] 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, a vertical direction). The top surface (outer peripheral top surface) of the outer periphery 10a engages with, for example, a jig (not shown) for fixing the electrostatic chuck 1. 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.

[0025] 2, a chuck electrode 13 made of a conductive material (e.g., tungsten, molybdenum, platinum, etc.) is disposed inside the plate-shaped member 10. The shape of the chuck electrode 13 as viewed in the Z-axis direction is, for example, substantially circular. When power is supplied to the chuck electrode 13 from the outside, electrostatic attraction is generated, and the semiconductor wafer W is attracted and held on the holding surface 11 of the plate-shaped member 10 by this electrostatic attraction.

[0026] A heater electrode 14 made of a resistance heating element containing a conductive material (e.g., tungsten, molybdenum, platinum, etc.) is disposed inside the plate-shaped member 10. When power is supplied to the heater electrode 14 from the outside, the heater electrode 14 generates heat, thereby heating the plate-shaped member 10, and the semiconductor wafer W held on the holding surface 11 of the plate-shaped member 10 is warmed.

[0027] 3, a circumferential first step 31 on which the inner protective member 50 is disposed, and a second step 32 on which the outer protective member 60 is disposed are formed on the underside 12 of the outer periphery of the plate-shaped member 10. The first step 31 has a side surface 31a substantially parallel to the Z-axis direction and a bottom surface 31b substantially perpendicular to the Z-axis direction, and has an L-shaped cross section. Similarly, the second step 32 has a side surface 32a substantially parallel to the Z-axis direction and a bottom surface 32b substantially perpendicular to the Z-axis direction, and has an L-shaped cross section.

[0028] As shown in Fig. 2, the base member 20 is a cylindrical member having the same diameter as (or a larger diameter than) the outer periphery 10a of the plate-like member 10. The base member 20 is preferably made of a metal (e.g., aluminum or an aluminum alloy), but may be made of a material other than metal. 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 central axis direction (i.e., the Z-axis direction) of the base member 20 (plate-like member 10). 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.

[0029] The diameter of the base member 20 is, for example, about 220 mm to 550 mm (usually, 220 mm to 350 mm), and the thickness of the base member 20 is, for example, about 20 mm to 40 mm.

[0030] Further, 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 manner, the coolant is caused to flow through the coolant flow path 23 of the base member 20, whereby the plate-like member 10 is cooled via the bonding layer 40.

[0031] 3, a circumferential first step 35 on which the inner protective member 50 is disposed and a second step 36 on which the outer protective member 60 is disposed are formed on the upper surface 21 side of the outer periphery of the base member 20. The first step 35 has a side surface 35a substantially parallel to the Z-axis direction and a bottom surface 35b substantially perpendicular to the Z-axis direction, and has an L-shaped cross section. Similarly, the second step 36 has a side surface 36a substantially parallel to the Z-axis direction and a bottom surface 36b substantially perpendicular to the Z-axis direction, and has an L-shaped cross section.

[0032] 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 and 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 bonding layer 40 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 bonding layer 40 is, for example, about 0.1 mm to 1.0 mm. The thermal conductivity of the bonding layer 40 is, for example, 1.0 W / mK. The thermal conductivity of the bonding layer 40 (assuming a silicone resin) is desirably within a range of 0.1 W / mK to 2.0 W / mK (preferably, 0.5 W / mK to 1.5 W / mK).

[0033] In this embodiment, the position of the outer peripheral surface 40a of the bonding layer 40 is approximately the same as the position of the side surface 31a of the first step portion 31 of the plate-like member 10 and the position of the side surface 35a of the first step portion 35 of the base member 20, but may be recessed inward.

[0034] The inner protective member 50 and the outer protective member 60 are members for protecting the bonding layer 40 from plasma and process gas. The inner protective member 50 has both ends disposed on the first step portions 31 and 35, and the outer protective member 60 has both ends disposed on the second step portions 32 and 36.

[0035] The inner protective member 50 is a member having a substantially circular ring shape when viewed in the Z-axis direction. The inner protective member 50 is formed of an elastomer (e.g., synthetic rubber, etc.) or a resin (e.g., fluororesin, etc.). The material forming the inner protective member 50 is preferably a material having elasticity and excellent plasma resistance, heat resistance, and chemical resistance. The material forming the inner protective member 50 is preferably a relatively soft material.

[0036] The dimension of the inner protective member 50 in the Z-axis direction (the vertical direction in FIG. 3) is approximately equal to the total dimension of the dimension of the side surface 31a in the Z-axis direction, the thickness of the bonding layer 40, and the dimension of the side surface 35a in the Z-axis direction. The inner protective member 50 is disposed in the first step portion 31, 35 with the inner circumferential side in contact with both the side surface 31a and the side surface 35a at both ends in the Z-axis direction and with both ends in the Z-axis direction in contact with both the bottom surfaces 31b, 32b. As a result, the inner protective member 50 covers the entire outer circumferential surface 40a of the bonding layer 40. Note that the dimension of the inner protective member 50 in the Z-axis direction may be smaller than the total dimension, as long as the inner protective member 50 is in contact with the side surface 31a and the side surface 35a at both ends in the Z-axis direction. The dimension of the inner protection member 50 in the Z-axis direction is, for example, about 0.3 mm to 6.0 mm, and the width dimension (dimension in the X-axis or Y-axis direction (horizontal direction in FIG. 3)) is, for example, about 0.3 mm to 2.0 mm.

[0037] The outer protective member 60 is also a substantially annular member as viewed in the Z-axis direction, similar to the inner protective member 50. The outer protective member 60 is formed of, for example, an elastomer (for example, synthetic rubber, etc.) or a resin (for example, fluororesin, etc.). The material forming the outer protective member 60 is preferably a material having elasticity and excellent plasma resistance, heat resistance, and chemical resistance, and the outer protective member 60 is preferably a material having greater elasticity than the inner protective member 50. This is because the outer protective member 60 can effectively press the inner protective member 50 inward. The elasticity can be measured by measuring the elastic modulus based on the dimensional change before and after a tensile test. Specifically, the measurement is based on JIS K 6251:2017, JIS K 7137-2:2001, JIS K 7161-1 2014, etc. The outer protective member 60 is preferably a material having a smaller thermal expansion coefficient than the inner protective member 50. As a result, even if the inner protective member 50 is partially twisted or tilted due to a difference in the thermal expansion coefficient between the inner protective member 50 and the bonding layer 40 (or the outer protective member 60), the twist or tilt of the inner protective member 50 can be corrected by the outer protective member 60. Furthermore, stretchability refers to the property of returning to the original shape (e.g., elasticity), and if the elastic force of the outer protective member 60 is greater than the elastic force of the inner protective member 50, the outer protective member 60 can effectively press the inner protective member 50 inward.

[0038] The dimension of the outer protective member 60 in the Z-axis direction (the vertical direction in FIG. 3) is larger than the dimension of the inner protective member 50 in the Z-axis direction, and the inner circumferential side of the outer protective member 60 contacts both the side surface 32a and the side surface 36a at both ends in the Z-axis direction, while both ends in the Z-axis direction do not contact the bottom surface 32b and the bottom surface 36b (so that there is a gap between the outer protective member 60 and the bottom surfaces 32b and 36b), and is disposed in the second step portion 32, 36. As a result, the inner protective member 50 is covered by the outer protective member 60. Note that in this embodiment, the outer protective member 60 contacts both the side surface 32a and the side surface 36a at both ends in the Z-axis direction, but since the outer protective member 60 only needs to cover the entire outer circumferential surface of the inner protective member 50, it is sufficient that the outer protective member 60 contacts at least one of the side surface 32a or the side surface 36a. The dimension of the outer protective member 60 in the Z-axis direction is, for example, about 0.3 mm to 7.0 mm, and the width dimension (dimension in the X-axis or Y-axis direction (horizontal direction in FIG. 3)) is, for example, about 0.3 mm to 2.0 mm.

[0039] The outer protective member 60 presses the inner protective member 50 inward (toward the center of the electrostatic chuck 1 as viewed in the Z-axis direction). Note that the pressing of the inner protective member 50 by the outer protective member 60 can be achieved, for example, by setting the size (outer diameter) of the outer protective member 60 before installation as viewed in the Z-axis direction to be smaller than the size (outer diameter) of the outer protective member 60 after installation so that tension is generated in the outer protective member 60 when the outer protective member 60 is installed.

[0040] That is, if tension is generated in the outer protective member 60 in a state where the outer protective member 60 is installed so as to cover the outer periphery of the inner protective member 50, the outer protective member 60 can press the inner protective member 50. Even if the width dimension (dimension in the X-axis or Y-axis direction (horizontal direction in FIG. 3)) of the inner protective member 50 is larger than the dimension in the radial direction (X-axis or Y-axis direction) of the bottom surfaces 31b, 35b, the outer protective member 60 in the installed state can press the inner protective member 50. In this embodiment, the outer protective member 60, which is larger than the inner protective member 50, is arranged in the second step portion 32, 36 so that a gap exists between the outer protective member 60 and the bottom surfaces 32b, 36b. Therefore, the outer protective member 60 is not hindered from contacting the bottom surfaces 32b, 36b and deforming to contract inward. Therefore, when the outer protective member 60 is placed on the second step portions 32, 36, the tension generated in the outer protective member 60 is not reduced, and the outer protective member 60 can firmly press against the inner protective member 50.

[0041] The outer protective member 60 is configured to be contained within the second step portions 32, 36 when it is installed so as to cover the outer periphery of the inner protective member 50. That is, the outer peripheral surface of the outer protective member 60 does not protrude from the outer peripheral surface of the outer peripheral portion 10a of the plate-like member 10 and the outer peripheral surface of the base member 20. This prevents the outer protective member 60 from interfering with the focus ring when the focus ring is attached to the electrostatic chuck 1. The focus ring is an annular member used to maintain the plasma density at the periphery of the semiconductor wafer W at approximately the same level as the plasma density at the center of the semiconductor wafer W.

[0042] When the electrostatic chuck 1 as described above is used to fix a semiconductor wafer W in a vacuum chamber of a semiconductor manufacturing apparatus, if the plasma or process gas used in forming a circuit pattern on the semiconductor wafer W comes into contact with the bonding layer 40, the bonding layer 40 will be corroded. Therefore, in the electrostatic chuck 1 of the present embodiment, an inner protective member 50 and an outer protective member 60 are provided to prevent the plasma or process gas from coming into contact with the outer peripheral surface 40a of the bonding layer 40.

[0043] In this embodiment, the outer protective member 60, which has a larger dimension in the Z-axis direction than the inner protective member 50, is disposed in the second step portion 32, 36 so as to cover the inner protective member 50. Therefore, even if the inner protective member 50 disposed in the first step portion 31, 35 is twisted or tilted, the outer protective member 60 covers the entire outer peripheral surface of the inner protective member 50 from the outside, so that the twist or tilt of the inner protective member 50 is corrected. That is, it is possible to prevent the inner protective member 50 disposed in the first step portion 31, 35 from being twisted or tilted. This allows the inner protective member 50 to reliably cover the entire outer peripheral surface 40a of the bonding layer 40.

[0044] Therefore, the inner protective member 50 and the outer protective member 60 can prevent plasma and process gas from entering near the outer peripheral surface 40a of the bonding layer 40. Even if the twist or inclination of the inner protective member 50 is not completely corrected and the inner protective member 50 is arranged offset toward the first step portions 31, 35, the outer protective member 60 covers the inner protective member 50, and therefore the outer protective member 60 can prevent plasma and process gas from entering near the outer peripheral surface 40a of the bonding layer 40.

[0045] In the electrostatic chuck 1 of the present embodiment, first steps 31, 35 for disposing the inner protective member 50 and second steps 32, 36 for disposing the outer protective member 60 are provided on the outer periphery on the lower surface 12 side of the plate-shaped member 10 and the outer periphery on the upper surface 21 side of the base member 20. Therefore, the inner protective member 50 and the outer protective member 60 can be disposed in appropriate positions without being misaligned.

[0046] That is, the inner protective member 50 can be disposed in the first step portion 31, 35 in a state where both ends of the inner protective member 50 are in contact with both the side surface 31a of the first step portion 31 and the side surface 35a of the first step portion 35. As a result, the entire outer peripheral surface 40a of the bonding layer 40 can be reliably covered by the inner protective member 50, so that the bonding layer 40 can be reliably sealed by the inner protective member 50. In addition, in this embodiment, both ends of the inner protective member 50 are in contact with both the bottom surface 31b of the first step portion 31 and the bottom surface 35b of the first step portion 35. Therefore, the sealing performance of the bonding layer 40 by the inner protective member 50 is improved. Furthermore, the outer protective member 60 can be disposed in the second step portion 32, 36 in a state where both ends of the outer protective member 60 are in contact with both the side surface 32a of the second step portion 32 and the side surface 36a of the second step portion 36. As a result, the entire inner protective member 50, which completely covers the entire outer peripheral surface 40a of the bonding layer 40, can be reliably covered by the outer protective member 60. Therefore, the bonding layer 40 can also be sealed by the outer protective member 60. In this manner, in this embodiment, the bonding layer 40 can be sealed by both the inner protective member 50 and the outer protective member 60, so that intrusion of plasma or process gas into the vicinity of the outer peripheral surface 40a of the bonding layer 40 can be reliably prevented.

[0047] In addition, since the outer protective member 60 has higher elasticity than the inner protective member 50, the outer protective member 60 can press the inner protective member 50 inward more effectively. Therefore, the inner protective member 50 arranged in the first step portions 31, 35 can be reliably prevented from being partially twisted or tilted. Therefore, the sealing performance of the bonding layer 40 by the inner protective member 50 can be further improved. This makes it possible to more effectively prevent the intrusion of plasma and process gas into the vicinity of the outer circumferential surface 40a of the bonding layer 40.

[0048] Here, a modified example will be described with reference to Fig. 4. As shown in Fig. 4, the modified example has the same basic configuration as the above embodiment, but differs from the above embodiment in the shape of the inner protective member 150. That is, in the modified example, the outer peripheral surface 150a of the inner protective member 150 is formed in an arc shape that is convex outward in the radial direction (X-axis or Y-axis direction).

[0049] In this modification, similarly to the above embodiment, the inner protective member 150 is disposed in the first step portion 31, 35 so as to cover the entire outer peripheral surface 40a of the bonding layer 40, and the outer protective member 60 is disposed in the second step portion 32, 36 so as to cover the entire outer peripheral surface 150a of the inner protective member 150. In the modification, the outer peripheral surface 150a of the inner protective member 150 has an arc shape that is convex outward, so that the outer protective member 60 can press the inner protective member 150 inward more effectively. Therefore, the sealing performance of the bonding layer 40 by the inner protective member 150 can be further improved, so that the intrusion of plasma and process gas into the vicinity of the outer peripheral surface 40a of the bonding layer 40 can be more effectively prevented.

[0050] As described above, according to the electrostatic chuck 1 of the present embodiment, the inner protective member 50 is disposed so as to cover the outer peripheral surface 40a of the bonding layer 40, and the outer protective member 60, which has a dimension in the Z-axis direction larger than that of the inner protective member 50, is disposed so as to cover the inner protective member 50. This makes it possible to prevent the inner protective member 50 from being twisted or tilted, and therefore makes it possible to reliably cover the entire outer peripheral surface 40a of the bonding layer 40 with the inner protective member 50. Therefore, the inner protective member 50 and the outer protective member 60 can prevent the plasma or the process gas from entering the vicinity of the outer peripheral surface 40a of the bonding layer 40.

[0051] Since the inner protective member 50 is disposed on the first step portions 31, 35 provided on the plate-like member 10 and the base member 20, and the outer protective member 60 is disposed on the second step portions 32, 36, respectively, the inner protective member 50 and the outer protective member 60 can be disposed in appropriate positions without misalignment. Therefore, the entire inner protective member 50 in a state in which the entire outer circumferential surface 40a of the bonding layer 40 is reliably covered by the outer protective member 60, so that the bonding layer 40 can be reliably sealed by the inner protective member 50 and intrusion of plasma and process gas into the bonding layer 40 can be prevented.

[0052] It should be noted that the above-described embodiment is merely an example, 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 present disclosure is applied to an electrostatic chuck, but the present disclosure is not limited to electrostatic chucks and can be applied to any holding device that holds an object on its surface. [Explanation of symbols]

[0053] 1. Electrostatic chuck 10 Plate-shaped member 11 Holding surface 12 Bottom side 20 Base material 21 Top side 22 Bottom side 31 First Stage 32 Second Stage 35 First Stage 36 Second Stage 40 Bonding layer 50 Inner protective member 60 Outer protection member 150 Inner protective member 150a Outer surface W Semiconductor wafer

Claims

1. A first member including a first surface and a second surface provided on an opposite side to the first surface in a first direction; a second member including a third surface and a fourth surface provided on an opposite side of the third surface in the first direction; 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, An inner protective member arranged to cover the entire outer circumferential surface of the bonding layer; an outer protective member disposed outside the inner protective member and having a dimension in the first direction larger than that of the inner protective member; The outer protective member is disposed so as to cover the entire outer peripheral surface of the inner protective member, a first step for disposing the inner protective member and a second step for disposing the outer protective member are formed on an outer periphery of the first member on the second surface side and an outer periphery of the second member on the third surface side, the inner protective member is in contact with both a side surface of the first step portion of the first member and a side surface of the first step portion of the second member, The outer protective member is in contact with at least one of a side surface of the second step portion of the first member and a side surface of the second step portion of the second member. A holding device characterized in that

2. 2. The holding device according to claim 1, The outer protective member has a higher elasticity than the inner protective member. A holding device characterized in that

3. The holding device according to claim 1 or 2, The outer protective member presses the inner protective member inwardly in a second direction perpendicular to the first direction. A holding device characterized in that

4. The holding device according to claim 1 or 2, The outer circumferential surface of the inner protective member is formed in an arc shape that is convex outward in a second direction perpendicular to the first direction. A holding device characterized in that

5. In any one of the holding devices described in claims 1 to 4, the outer protective member is disposed between a bottom surface of the second step portion of the first member and a bottom surface of the second step portion of the second member, A gap exists between the outer protective member and the bottom surface of the second step portion of the first member, and a gap exists between the outer protective member and the bottom surface of the second step portion of the second member. A holding device characterized in that

6. In any one of the holding devices described in claims 1 to 5, A holding device, wherein the outer protective member has a smaller coefficient of thermal expansion than the inner protective member.

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