Retention device

Abstract

To provide a holding device capable of improving thermal uniformity on a holding surface around a penetration hole.SOLUTION: In an electrostatic chuck 1, a first penetration hole 15 penetrating a holding surface 11 and a bottom face 12 is formed in a tabular member 10, and a second penetration hole 25 penetrating a top face 21 and a bottom face 22 and communicating to the first penetration hole 15 is formed in a base member 20. A third penetration hole 45 communicating to the first penetration hole 15 and the second penetration hole 25 is formed in a joint layer 40. A holding device includes an annular seal member 50 disposed between the bottom face 12 and the top face 21 in such a manner that a central axis CL of the third penetration hole 45 is positioned inside off its own inner periphery in a view in a lamination direction of the tabular member 10 and the base member 20. An annular recess 13 in which the seal member 50 is disposed is formed on the bottom face 12, and both corners 13a of the annular recess 13 are formed in an arcuate shape in which a width dimension of the annular recess 13 becomes larger in a direction from a bottom to an opening of the annular recess 13.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] As a holding device, for example, Patent Document 1 discloses an electrostatic chuck device (holding device) including an electrostatic chuck part (first member), a base part (second member), and an adhesive layer (bonding layer) that bonds and integrates the electrostatic chuck part and the base part, and through holes are formed in these in the thickness direction. In such an electrostatic chuck device during use, there is a risk that plasma may enter the through holes and erode the adhesive layer. Therefore, around the through holes, a seal member for protecting the adhesive layer and a groove part (recess) for arranging the seal member are provided.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the holding device as described above, in the seal part provided with the seal member and the recess, heat transfer between the first member and the second member deteriorates. Therefore, the temperature difference between the periphery of the through hole and other parts on the holding surface (first surface) becomes large, and the heat uniformity on the holding surface deteriorates.

[0005] Therefore, the present disclosure has been made to solve the above - described problems, and an object thereof is to provide a holding device capable of improving the heat uniformity on the holding surface around the through hole.

Means for Solving the Problems

[0006] One aspect of the present disclosure made to solve the above problems is a first member including a first surface and a second surface provided on the side opposite to the first surface, a second member including a third surface and a fourth surface provided on the side opposite to the third surface, 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, in a holding device that holds an object on the first surface of the first member, a first through hole penetrating the first surface and the second surface is formed in the first member, a second through hole penetrating the third surface and the fourth surface and communicating with the first through hole is formed in the second member, a third through hole communicating with the first through hole and the second through hole is formed in the bonding layer, an annular seal member disposed between the second surface and the third surface such that the central axis of the third through hole is located inside the inner circumference thereof when viewed from the lamination direction of the first member and the second member, an annular recess in which the seal member is disposed is formed in the second surface, both corners of the recess are shaped such that the width dimension of the recess increases from the bottom of the recess toward the opening side of the recess.

[0007] In this holding device, both corners of the annular recess in which the seal member is disposed are shaped such that the width dimension of the recess increases from the bottom of the recess toward the opening. Therefore, the volume of the first member (in the vertical direction, that is, the volume in the lamination direction of the first member and the second member) at both corners of the recess increases. Accordingly, the heat conduction in the lamination direction in the vicinity of the recess is averaged, that is, the heat conduction is improved. Thereby, in the seal portion around the through hole, the change (temperature gradient) in the temperature distribution on the first surface (holding surface) can be moderated, and the heat uniformity on the first surface (holding surface) can be improved.

[0008] In addition, when the corners include an arc (R) shape or a tapered shape, stress concentration that is likely to occur at both corners of the concave portion is alleviated. Therefore, damage to the first member can be prevented, and the reliability and long life of the holding device can be improved.

[0009] In the holding device described above, it is preferable that the width dimension of the concave portion is minimized at the opening, and the minimum dimension is smaller than the width dimension of the seal member.

[0010] By forming the concave portion into such a shape, the volume of the first member in the vicinity where the seal member is disposed (the volume in the vertical direction, that is, the volume in the lamination direction of the first member and the second member) further increases. Therefore, since the heat conduction in the lamination direction in the vicinity of the concave portion is more averaged (that is, the heat conduction is improved), the heat uniformity on the first surface can be further improved.

[0011] In addition, since the seal member can be fixed at the opening of the concave portion, the deviation of the seal member within the concave portion can be suppressed. Therefore, the seal member that deteriorates the heat conduction between the first member and the second member always exists at the same position. As a result, the change in the temperature distribution on the first surface due to the deviation of the seal member is eliminated. Therefore, the temperature controllability on the first surface is improved, and the stabilization of the heat uniformity can be achieved.

[0012] Furthermore, since the seal member is fixed at the opening of the concave portion, the reaction force from the seal member during thermal expansion can be suppressed. Therefore, it is also possible to prevent the occurrence of poor bonding between the first member and the second member due to breakage of the bonding layer.

[0013] In addition, in the holding device described above, the first member and the second member may be ceramic members.

[0014] By doing so, compared with the case where the first member and the second member are made of different materials, the difference in thermal expansion between the first member and the second member becomes smaller, so the stress acting on the seal member becomes smaller. Therefore, deterioration of the seal member can be prevented, and the corrosion resistance of the bonding layer can be improved. Also, since the stress acting on the seal member becomes smaller, the reaction force from the seal member received by the first member is suppressed. Therefore, stress concentration that easily occurs at both corners of the concave portion can be alleviated. Accordingly, damage to the first member can be effectively prevented, so that the reliability and durability of the holding device can be further improved.

Advantages of the Invention

[0015] According to the present disclosure, it is possible to provide a holding device capable of improving the heat uniformity on the holding surface around the through hole.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0017] 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 that holds a semiconductor wafer as an object will be described as an example.

[0018] [First Embodiment] First, the electrostatic chuck 1 of the first embodiment will be described with reference to FIGS. 1 to 4. The electrostatic chuck 1 of the present embodiment is a device that adsorbs 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 apparatus. 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. In this embodiment, the plate-like member 10 is an example of the "first member" of the present disclosure, and the base member 20 is an example of the "second member" of the present disclosure.

[0019] In the following description, for convenience of explanation, the XYZ axes are defined as shown in FIG. 1. Here, the Z axis is the axis in the axial direction (the vertical direction in FIG. 1) of the electrostatic chuck 1, and the X axis and the Y axis are the axes in the radial direction of the electrostatic chuck 1. In this embodiment, the Z-axis direction is an example of the "lamination direction" of the present disclosure.

[0020] As shown in FIG. 1, the plate-like member 10 is a disk-shaped member formed of ceramics. Various ceramics can be used as the ceramics, but from the viewpoints of strength, wear resistance, plasma resistance, etc., for example, ceramics mainly composed of aluminum oxide (alumina, Al2O3) or aluminum nitride (AlN) are preferably used. Here, the main component means the component with the highest content ratio (for example, the component with a volume content ratio of 90 vol% or more). The diameter of the plate-like member 10 is about 150 mm to 350 mm, and the thickness of the plate-like member 10 is, for example, about 2 mm to 6 mm.

[0021] As shown in FIGS. 1 and 2, the plate-like member 10 includes a holding surface 11 for holding the semiconductor wafer W and a lower surface 12 provided on the side opposite to the holding surface 11 in the thickness direction (the direction coinciding with the Z-axis direction, the vertical direction) of the plate-like member 10. And cylindrical first through-holes 15a and 15b penetrating in the thickness direction (Z-axis direction, vertical direction in FIG. 2) are formed between the holding surface 11 and the lower surface 12. Note that the holding surface 11 is an example of the "first surface" of the present disclosure, and the lower surface 12 is an example of the "second surface" of the present disclosure.

[0022] The holding surface 11 of the plate-like member 10 has an uneven shape. Specifically, as shown in FIGS. 2 and 3, an annular convex portion 16 (so-called seal band) is formed near the outer edge of the holding surface 11, and a plurality of independent columnar convex portions 17 are formed inside the annular convex portion 16. The shape of the cross section (XZ cross section) of the annular convex portion 16 is substantially rectangular as shown in FIG. 2. The height (dimension in the Z-axis direction) of the annular convex portion 16 is, for example, about 10 μm to 20 μm. Further, the width (dimension in the X-axis direction) of the annular convex portion 16 is, for example, about 0.5 mm to 5.0 mm.

[0023] As shown in FIG. 3, each convex portion 17 is substantially circular in a view from the Z-axis direction (plan view) and is arranged at substantially equal intervals. Also, the shape of the cross section (XZ cross section) of each convex portion 17 is substantially rectangular as shown in FIG. 2. The height of the convex portion 17 is substantially the same as the height of the annular convex portion 16 and is, for example, about 10 μm to 20 μm. Further, the width (the maximum diameter of the convex portion 17 in a view from the Z-axis direction) of the convex portion 17 is, for example, about 0.5 mm to 1.5 mm. Note that, inside the annular convex portion 16 on the holding surface 11 of the plate-like member 10, the portion where the convex portion 17 is not formed is a concave portion 18.

[0024] The semiconductor wafer W is supported by the annular convex portion 16 and the plurality of convex portions 17 on the holding surface 11 of the plate-like member 10 and held by the electrostatic chuck 1. In a state where 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 (specifically, the recess 18 of the holding surface 11) (see FIG. 2). An inert gas (for example, helium gas) is supplied to this space S through a gas hole 30b described later.

[0025] In such a plate-like member 10, cylindrical first through-holes 15a and 15b (hereinafter, may also be referred to as "first through-holes 15") penetrating in the thickness direction (Z-axis direction, vertical direction in FIG. 2) between the holding surface 11 and the lower surface 12 are formed. Then, as shown in FIGS. 2 and 4, an annular recess 13 for arranging an annular seal member 50 described later is formed around the first through-holes 15a and 15b on the lower surface 12.

[0026] As shown in FIG. 4, both corner portions 13a of the annular recess 13 have a shape in which the width dimension of the annular recess 13 increases from the bottom to the opening. In the present embodiment, both corner portions 13a are processed into, for example, an arc (R) shape, and the size of the arc (radius R) is about R = 0.05 mm to 5.0 mm, and more preferably R = 0.1 mm to 0.5 mm. The width dimension of the annular recess 13 is the dimension in the X-axis direction in the ZX cross-section of the annular recess 13.

[0027] As shown in FIG. 1, the base member 20 is columnar. Specifically, two cylinders with different diameters are stacked such that the lower cylindrical surface portion with a small diameter is placed on the upper surface portion of the large-diameter cylindrical shape, and is formed as a stepped columnar shape with a common central axis Ca (see FIG. 2). This base member 20 is preferably formed of a metal (for example, aluminum, an aluminum alloy, etc.), but may be other than a metal.

[0028] Then, as shown in FIGS. 1 and 2, the base member 20 includes an upper surface 21 and a lower surface 22 provided on the side opposite to the upper surface 21 in the direction of the central axis Ca (see FIG. 2) of the base member 20 (plate-like member 10) (i.e., the Z-axis direction). The upper surface 21 is an example of the "third surface" of the present disclosure, and the lower surface 22 is an example of the "fourth surface" of the present disclosure.

[0029] The diameter of the base member 20 is, for example, about 150 mm to 300 mm in the upper stage portion and about 180 mm to 350 mm in the lower stage portion. Also, the thickness (dimension in the Z-axis direction) of the base member 20 is, for example, about 20 mm to 50 mm.

[0030] Also, as shown in FIG. 2, a refrigerant flow path 23 for flowing a refrigerant (e.g., fluorine-based inert liquid, water, etc.) is formed in the base member 20. The refrigerant 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 refrigerant supplied to the base member 20 from the supply port flows through the refrigerant flow path 23 and is discharged from the base member 20 through the discharge port. In this way, by flowing the refrigerant in the refrigerant flow path 23 of the base member 20, the base member 20 is cooled, and thereby the plate-like member 10 is cooled via the bonding layer 40.

[0031] And, cylindrical second through-holes 25a and 25b (hereinafter, may also be referred to as "second through-holes 25") penetrating in the thickness direction (Z-axis direction, vertical direction in FIG. 2) between the upper surface 21 and the lower surface 22 are formed in the base member 20. The second through-holes 25a and 25b are coaxial (the central axis CL coincides) with the first through-holes 15a and 15b, and the diameters of the second through-holes 25a and 25b are substantially the same as the diameters of the first through-holes 15a and 15b.

[0032] The bonding layer 40 is disposed between the lower surface 12 of the plate-like member 10 and the upper surface 21 of the base member 20, and bonds the plate-like member 10 and the base member 20. Through this bonding layer 40, the lower surface 12 of the plate-like member 10 and the upper surface 21 of the base member 20 are thermally connected. The bonding layer 40 is composed of an adhesive such as a silicone-based resin, an acrylic-based resin, or an epoxy-based resin. Note that the thickness (dimension in the Z-axis direction) of the bonding layer 40 is, for example, about 0.1 to 1.0 mm.

[0033] As shown in FIG. 2, third through holes 45a and 45b (hereinafter, may also be referred to as "third through holes 45") that communicate the first through holes 15a and 15b with the second through holes 25a and 25b are formed in the bonding layer 40. That is, cylindrical third through holes 45a and 45b are formed between the first through holes 15a and 15b and the second through holes 25a and 25b. The third through holes 45a and 45b are coaxial (the central axes CL coincide) with the first through holes 15a and 15b and the second through holes 25a and 25b. The diameters of the third through holes 45a and 45b are larger than those of the first through holes 15a and 15b and the second through holes 25a and 25b. The first through holes 15a and 15b, the third through holes 45a and 45b, and the second through holes 25a and 25b are arranged in series in the Z-axis direction (the axial direction of the electrostatic chuck 1).

[0034] Then, as shown in FIG. 2, a lift pin insertion hole 30a that penetrates the electrostatic chuck 1 in the Z-axis direction is formed by the first through hole 15a, the third through hole 45a, and the second through hole 25a. A lift pin 60 that pushes up the semiconductor wafer W from above the holding surface 11 is inserted into the lift pin insertion hole 30a from the lower surface 22 side of the base member 20. The lift pin 60 has a cylindrical shape (round bar shape) and moves in the Z-axis direction within the lift pin insertion hole 30a. When the lift pin 60 moves to one side in the Z-axis direction (the upper side in FIG. 2) and the tip end portion (upper end portion) of the lift pin 60 protrudes outside the holding surface 11 of the plate-like member 10, the semiconductor wafer W placed on the holding surface 11 is separated from the holding surface 11 (the semiconductor wafer W is lifted by the lift pin 60).

[0035] In the electrostatic chuck 1 of the present embodiment, three lift pin insertion holes 30a are formed, and lift pins 60 are inserted into the respective lift pin insertion holes 30a. The three lift pin insertion holes 30a are formed at equal intervals in the circumferential direction of the electrostatic chuck 1 (see FIG. 3).

[0036] Further, a gas hole 30b penetrating the electrostatic chuck 1 in the Z-axis direction is formed by the first through hole 15b, the third through hole 45b, and the second through hole 25b. This gas hole 30b is a gas flow path through which an inert gas (for example, helium gas) flows. By supplying an inert gas (for example, helium gas) into the gas hole 30b from the lower surface 22 side of the base member 20, the space S between the lower surface of the semiconductor wafer W and the holding surface 11 (recess 18) of the plate-like member 10 can be filled with this inert gas. In the following description, the lift pin insertion hole 30a and the gas hole 30b may be simply referred to as "through hole 30".

[0037] And in such an electrostatic chuck 1, an annular seal member 50 is disposed in each third through hole 45 (through hole of the bonding layer 40) so as to be sandwiched between the plate-like member 10 and the base member 20 and surround the first through hole 15 and the second through hole 25 in a view from the Z-axis direction. In other words, the third through hole 45 is located inside the inner circumference of itself (see FIGS. 2 and 4). This seal member 50 is for protecting the bonding layer 40 and preventing corrosion of the bonding layer 40.

[0038] That is, when the electrostatic chuck 1 is used to fix the semiconductor wafer W in the vacuum chamber of the semiconductor manufacturing apparatus, a processing gas, plasma, etc. used when forming a circuit pattern on the semiconductor wafer W flows into the electrostatic chuck 1 through the first through hole 15. And when the plasma or the like penetrates and contacts the bonding layer 40, the bonding layer 40 will be corroded, so the seal member 50 is provided. The seal member 50 is in an annular or tubular shape and is composed of an arbitrarily selected material, for example, an elastic body such as rubber or an elastomer resin.

[0039] By providing such a sealing member 50, the space between the lower surface 12 of the plate-like member 10 and the upper surface 21 of the base member 20 is hermetically sealed. As a result, the sealing member 50 can prevent plasma or the like that has flowed into the electrostatic chuck 1 through the first through-hole 15 from entering the bonding layer 40 through the third through-hole 45 and contacting the bonding layer 40.

[0040] However, in the sealing portion provided with the sealing member 50 and the annular recess 13, heat transfer between the plate-like member 10 and the base member 20 deteriorates. Therefore, the temperature difference between the periphery of the through-hole 30 and other portions on the holding surface 11 becomes large, and the heat uniformity on the holding surface 11 deteriorates at the periphery of the through-hole 30.

[0041] Therefore, in the electrostatic chuck 1 of the present embodiment, as shown in FIG. 4, both corner portions 13a of the annular recess 13 are formed in an arc (R) shape in which the width dimension of the annular recess 13 increases from the bottom of the annular recess 13 toward the opening. Further, as shown in FIG. 5, the annular recess 13 is composed of both corner portions 13a, a bottom portion 13b, and side wall portions 13c, and both corner portions 13a are formed inside the portion where the extension line of the bottom portion 13b and the extension line of the side wall portion 13c intersect. Therefore, compared with the case where the extension line of the bottom portion 13b and the extension line of the side wall portion 13c intersect (when no corner portion is provided), the volume (volume in the Z-axis direction) of the plate-like member 10 at both corner portions 13a of the annular recess 13 increases when both corner portions 13a are formed in which the width dimension of the annular recess 13 increases from the bottom of the annular recess 13 toward the opening. That is, the volume of the plate-like member 10 increases in the hatched portion shown in FIG. 5. As a result, in the plate-like member 10, the heat conduction in the Z-axis direction in the vicinity of the annular recess 13 is averaged, that is, the heat conduction is improved. Therefore, in the sealing portion around the through-hole 30, the change (temperature gradient) in the temperature distribution on the holding surface 11 can be moderated, and the heat uniformity on the holding surface 11 can be improved. Since the annular recess 13 is formed with both corner portions 13a not only on one side but also on both sides, it becomes easier to further increase the volume (volume in the Z-axis direction) of the plate-like member 10.

[0042] In addition, since both corner portions 13a of the annular recess 13 are arc-shaped, stress concentration that easily occurs at both corner portions 13a of the annular recess 13 can be alleviated. As a result, damage to the plate-like member 10 can be prevented, and thus the reliability and high durability of the electrostatic chuck 1 can be achieved.

[0043] As described above, according to the electrostatic chuck 1 of the present embodiment, since both corner portions 13a in the annular recess 13 where the seal member 50 is disposed have an arc (R) shape, heat conduction at both corner portions 13a of the annular recess 13 is averaged, and heat conduction is improved. Therefore, in the seal portion around the through hole 30, the change (temperature gradient) in the temperature distribution on the holding surface 11 can be moderated, and the heat uniformity on the holding surface 11 can be improved.

[0044] [Second Embodiment] Next, a second embodiment will be described. The second embodiment has the same basic structure as the first embodiment, but the shape of the annular recess where the seal member is disposed is different from that of the first embodiment. That is, in the second embodiment, the cross-sectional shape of the annular recess is such that the width dimension is minimized at the opening (see FIG. 6). Therefore, the same reference numerals are given to the same configurations as those in the first embodiment, and the description thereof is appropriately omitted, and the description will be centered on the differences from the first embodiment.

[0045] In the electrostatic chuck 1a of the present embodiment, as shown in FIG. 6, the annular recess 73 has a width dimension that is minimized at the opening, and the minimum dimension is processed to be smaller than the width dimension of the seal member 50. In the present embodiment, the annular recess 73 has, for example, a so-called anti-creep groove shape.

[0046] Therefore, in the electrostatic chuck 1a, the volume of the plate-like member 10 (volume in the Z-axis direction) in the vicinity where the seal member 50 is disposed further increases. As a result, heat conduction in the vicinity of the annular recess 73 is more averaged, and heat conduction is further improved, so that the heat uniformity on the holding surface 11 can be further improved.

[0047] In addition, since the sealing member 50 can be fixed at the opening of the annular recess 73, it is possible to suppress the deviation of the sealing member 50 within the annular recess 73. In other words, the sealing member 50 can always be arranged at the same position in the annular recess 73. Therefore, the sealing member 50 that deteriorates the heat conduction between the plate-like member 10 and the base member 20 will always be present at the same position. As a result, the change in the temperature distribution on the holding surface 11 due to the deviation of the sealing member 50 is eliminated, so that the temperature controllability on the holding surface 11 is improved, and the stabilization of the heat uniformity can be achieved. In the annular recess 13, since the corners are formed as both corners 13a not only on one side but also on both sides, it is advantageous in terms of making it easier to further increase the volume of the plate-like member 10 (the volume in the Z-axis direction) and suppressing the deviation of the sealing member 50.

[0048] Furthermore, since the sealing member 50 is fixed at the opening of the annular recess 73, it is possible to suppress the reaction force from the sealing member 50 during thermal expansion. Therefore, the stress concentration that is likely to occur at both corners 73a of the annular recess 73 can be further alleviated, and damage to the plate-like member 10 can be prevented. As a result, further improvement in the reliability and longer life of the electrostatic chuck 1a can be achieved. In addition, the occurrence of poor bonding between the plate-like member 10 and the base member 20 due to the breakage of the bonding layer 40 can also be prevented.

[0049] [Third Embodiment] Finally, the third embodiment will be described. The basic structure of the third embodiment is the same as that of the first embodiment, but the configuration of the plate-like member is different from that of the first embodiment. Therefore, the same reference numerals will be given to the same configurations as those in the first embodiment, and the description will be appropriately omitted, and the description will be centered on the differences from the above embodiments.

[0050] In the electrostatic chuck 1b of the third embodiment, as shown in FIG. 7, the plate-like member 100 includes a first ceramic member 110, a second ceramic member 120, and a bonding layer 140 that bonds the first ceramic member 110 and the second ceramic member 120. The first ceramic member 110 is an example of the "first member" of the present disclosure, and the second ceramic member 120 is an example of the "second member" of the present disclosure.

[0051] Further, the electrostatic chuck 1b includes a base member 20 similar to that of the first embodiment and a bonding layer 40 that bonds the plate-like member 100 (second ceramic member 120). Further, similar to the first embodiment, an annular seal member 50 is disposed in the third through-hole 45 in a manner sandwiched between the lower surface 122 of the second ceramic member 120 and the upper surface 21 of the base member 20. Note that the seal member 50 is disposed in an annular recess 123 formed in the lower surface 122 of the plate-like member 100 (second ceramic member 120), similar to the first embodiment. The annular recess 123 has the same shape as the annular recess 13 of the first embodiment.

[0052] Here, a cylindrical first through-hole 115 that penetrates in the Z-axis direction between the holding surface 111 and the lower surface 112 is formed in the first ceramic member 110 that constitutes the plate-like member 100. The holding surface 111 is an example of the "first surface" of the present disclosure, and the lower surface 112 is an example of the "second surface" of the present disclosure. Further, a cylindrical second through-hole 125 that penetrates in the Z-axis direction between the upper surface 121 and the lower surface 122 is formed in the second ceramic member 120. The upper surface 121 is an example of the "third surface" of the present disclosure, and the lower surface 122 is an example of the "fourth surface" of the present disclosure. Note that the second through-hole 125 is coaxial with the first through-hole 115 (the central axes CL coincide) and has an equivalent inner diameter. The first through-hole 115, the third through-hole 145, and the second through-hole 125 are arranged in series in the Z-axis direction to form a part of a through-hole 30 that penetrates the electrostatic chuck 1b in the Z-axis direction.

[0053] Further, an annular recess 113 for disposing the seal member 150 is formed around the first through-hole 115 on the lower surface 112 of the first ceramic member 110. Both corner portions 113a of this annular recess 113 have an arc (R) shape in which the width dimension of the annular recess 113 increases from the bottom of the annular recess 113 toward the opening, similar to the first embodiment. Note that the dimensions of the annular recess 113 (corner portions 113a) are the same as the dimensions of the annular recess 13 (corner portions 13a).

[0054] In the bonding layer 140, a cylindrical third through hole 145 is formed between the first through hole 115 and the second through hole 125. The third through hole 145 is coaxial with (the central axis CL coincides) the first through hole 115 and the second through hole 125, and has an inner diameter larger than those of the first through hole 115 and the second through hole 125.

[0055] To protect this bonding layer 140, a seal member 150 is disposed in the annular recess 113. In a view in the Z-axis direction, the central axis CL of the third through hole 145 is located inside the inner periphery of the seal member 150 so as to surround the first through hole 115 and the second through hole 125, and the seal member 150 is sandwiched between the lower surface 112 of the first ceramic member 110 and the upper surface 121 of the second ceramic member 120. Thereby, the seal member 150 hermetically seals the space between the lower surface 112 of the first ceramic member 110 and the upper surface 121 of the second ceramic member 120 that is exposed in the third through hole 145. Therefore, the seal member 150 can prevent plasma or the like that has flowed into the electrostatic chuck 1b through the first through hole 115 from entering the bonding layer 140 through the third through hole 145 and contacting the bonding layer 40.

[0056] And since both corner portions 113a of the annular recess 113 are formed in an arc (R) shape similar to that of the first embodiment, the volume of the first ceramic member 110 (volume in the Z-axis direction) at both corner portions 113a of the annular recess 113 increases. Thereby, in the first ceramic member 110, the heat conduction in the Z-axis direction in the vicinity of the annular recess 113 is averaged. Therefore, the heat conduction between the first ceramic member 110 and the second ceramic member 120 can be improved at the seal portion where the seal member 150 and the annular recess 113 are disposed. Accordingly, the change (temperature gradient) in the temperature distribution on the holding surface 111 can be moderated, and the heat uniformity on the holding surface 111 can be improved in the seal portion around the through hole 30.

[0057] In addition, since both corner portions 113a of the annular recess 113 are arc-shaped, stress concentration that is likely to occur at both corner portions 113a of the annular recess 113 can also be alleviated. Furthermore, since the difference in thermal expansion between the first ceramic member 110 and the second ceramic member 120 is small, the stress acting on the seal member 150 becomes small. Therefore, deterioration of the seal member 150 can be prevented, and the corrosion resistance of the bonding layer 140 can be improved. Also, since the stress acting on the seal member 150 becomes small, the reaction force from the seal member 150 received by the first ceramic member 110 is suppressed. Therefore, stress concentration that is likely to occur at both corner portions 113a of the annular recess 113 can be further alleviated. Accordingly, since damage to the first ceramic member 110 (plate-like member 100) can be effectively prevented, the reliability and durability of the electrostatic chuck 1b can be further improved.

[0058] Note that the above-described embodiments are merely examples and do not limit the present disclosure in any way. It goes without saying that various improvements and modifications are possible without departing from the gist thereof. For example, in the above-described embodiments, the case where the present disclosure is applied to an electrostatic chuck is exemplified, but the present disclosure can be applied not only to an electrostatic chuck but also to all holding devices that hold an object on a holding surface.

[0059] Also, in the above-described embodiments, the seal members 50 and 150 having a circular cross-section are exemplified, but the cross-sectional shape of the seal members 50 and 150 is not limited to this shape and may be square, elliptical, or the like.

[0060] Also, in the above-described embodiments, the case where both corner portions 13a and 113a of the annular recesses 13 and 113 are arc-shaped is exemplified, but both corner portions 13a and 113a only need to have an increasing width dimension of the annular recesses 13 and 113 from the bottom to the opening of the annular recesses 13 and 113, and are not limited to the arc shape, and may be a tapered shape, a polygonal shape, or the like.

Description of Reference Numerals

[0061] 1 Electrostatic chuck 1a Electrostatic chuck 1b Electrostatic chuck 10 Plate-like member 11 Holding surface 12 Bottom surface 13 Annular recess 13a Corner 15 First through-hole 20 Base member 21 Top surface 22 Bottom surface 25 Second through-hole 40 Bonding layer 45 Third through-hole 50 Sealing member 73 Annular recess 73a Corner 110 First ceramic member 113 Annular recess 120 Second ceramic member 150 Sealing member CL Central axis W Semiconductor wafer

Claims

1. A first member including a first surface and a second surface provided on the side opposite to the first surface, a second member including a third surface and a fourth surface provided on the side opposite to the third surface, and a joining layer disposed between the second surface of the first member and the third surface of the second member for joining the first member and the second member, in a holding device for holding an object on the first surface of the first member, a first through hole penetrating the first surface and the second surface is formed in the first member, a second through hole penetrating the third surface and the fourth surface and communicating with the first through hole is formed in the second member, a third through hole communicating with the first through hole and the second through hole is formed in the joining layer, an annular seal member disposed between the second surface and the third surface such that the central axis of the third through hole is located inside the inner circumference thereof when viewed in the stacking direction of the first member and the second member, an annular recess for disposing the seal member is formed in the second surface, both corners of the recess are shaped such that the width dimension of the recess increases from the bottom of the recess toward the opening side of the recess, the recess has an inner peripheral side wall surface and an outer peripheral side wall surface, the height of the inner peripheral side wall surface from the bottom is lower than the height of the outer peripheral side wall surface from the bottom, The holding device is characterized by the above.

2. In the holding device according to Claim 1, the width dimension of the recess is minimum at the opening, and the minimum dimension is smaller than the width dimension of the seal member The holding device is characterized by the above.

3. In the holding device according to Claim 1 or Claim 2, the first member and the second member are ceramic members The holding device is characterized by the above.

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