Holding device

Abstract

To provide a holding device including a plate-like member including a plurality of projections in which occurrence of particles (omitted particles) is suppressed.SOLUTION: A holding device 1 includes a base part 100 including a reference surface 111, and a plate-like member 10 having a plurality of projections 14 raised from the reference surface 111, wherein the projection 14 includes an opening 141 arranged on the central side, and a peripheral wall part 142 arranged in the periphery of the opening 141, and an upper surface 143 of the peripheral wall part 142 constitutes a seamless annular surface 143 or a discontinuous annular surface 143A partially including a cut line when being planarly viewed from the reference surface 111 side.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a retaining device. [Background technology]

[0002] An example of a holding device for holding a wafer (semiconductor wafer) during semiconductor manufacturing is an electrostatic chuck (see Patent Document 1). The electrostatic chuck includes a plate-shaped member mainly made of insulating ceramics (e.g., alumina), and the wafer is held on the surface of the plate-shaped member by electrostatic attraction. The electrostatic attraction is generated by applying a voltage to a chuck electrode provided inside the plate-shaped member.

[0003] As shown in Patent Document 1, the surface of the plate-shaped member has multiple protrusions, and the wafer is held by the plate-shaped member in a manner that it is placed on the upper surfaces of the protrusions. The protrusions are circular in plan view. A plate-shaped member having such multiple protrusions can be obtained, for example, by blasting a plate-shaped ceramic member. In this case, predetermined locations on the surface of the plate-shaped ceramic member are blasted so that multiple protrusions are formed on the surface. Thereafter, the surface of the ceramic member is polished to obtain a plate-shaped member having multiple protrusions. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2022-158499 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, when the surface of the ceramic member is polished during the formation of the convex portion, the convex portion becomes rounded. Therefore, the upper surface of the convex portion on which the wafer is placed becomes hemispherical (dome-shaped). Even if the upper surface of the convex portion is flat when the convex portion is formed, the upper surface of the convex portion may become hemispherical (dome-shaped) during use of the electrostatic chuck. When the wafer is held by the plate-shaped member, the wafer surface is pressed against the rounded upper surface of the convex portion, resulting in point contact between the wafer and the convex portion. In other words, when the wafer is held, a large local force is applied to the upper surface of the rounded convex portion, which can cause microcracks or friction with the wafer, resulting in the generation of particles (missing particles) from the convex portion. The generation of such particles can reduce the yield of the workpiece (wafer) held by the electrostatic chuck.

[0006] An object of the present invention is to provide a holding device having a plate-like member including a plurality of protrusions that suppresses the generation of particles (missing particles). [Means for solving the problem]

[0007] The means for solving the above problems are as follows: <1> A holding device comprising a plate-shaped member having a base including a reference surface and a plurality of protrusions that protrude from the reference surface, wherein the protrusions include an opening disposed at the center and a peripheral wall disposed around the opening, and the upper surface of the peripheral wall forms a continuous annular surface or a discontinuous annular surface that includes a break in part when viewed in a plane from the reference surface side.

[0008] <2> The peripheral wall portion has an annular shape when viewed from the reference surface side, and the upper surface of the peripheral wall portion forms a continuous circular annular surface. <1> The holding device according to claim 1.

[0009] <3> The peripheral wall portion has a discontinuous annular shape including one or more gaps when viewed in plan from the reference surface side, and the upper surface of the peripheral wall portion has a discontinuous circular annular surface including one or more gaps. <1> The holding device according to claim 1.

[0010] <4> When viewed from the reference plane side, the width of the annular surface is larger than the radius of the opening. <1> from <3> 10. A holding device according to any one of the preceding items.

[0011] <5> When a cross section obtained by cutting the peripheral wall portion of the protrusion in the thickness direction of the plate-like member is viewed, the upper surface of the peripheral wall portion has a convex shape that protrudes upward. <1> from <3> 10. A holding device according to any one of the preceding items. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a holding device including a plate-like member including a plurality of protrusions in which generation of particles (missing particles) is suppressed. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic perspective view of an electrostatic chuck according to a first embodiment; [Figure 2] FIG. 1 is a cross-sectional view schematically illustrating an internal structure of an electrostatic chuck according to a first embodiment. [Figure 3] 1 is a top view of an electrostatic chuck according to a first embodiment; [Figure 4] 1 is a top view of a protrusion of the first embodiment. [Figure 5] Cross section of line AA in Figure 4 [Figure 6] An explanatory diagram showing a method for forming convex portions by processing the surface of a ceramic member. [Figure 7] Top view of the convex portion of the second embodiment [Figure 8] 10 is a top view of the protrusion of the third embodiment. [Figure 9] 10 is a top view of the protrusion of the fourth embodiment. [Figure 10] 10 is a top view of the protrusion of the fifth embodiment. [Figure 11]10 is a top view of the protrusion of the sixth embodiment. [Figure 12] 10 is a top view of an electrostatic chuck according to a seventh embodiment of the present invention; [Figure 13] 10 is a top view of a protrusion according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] <Embodiment 1> The following describes the holding device of embodiment 1. In the following embodiment, a case where the holding device is applied to an electrostatic chuck 1 that holds a semiconductor wafer (object) W will be described.

[0015] The electrostatic chuck 1 is a device (an example of a holding device) that attracts and holds a semiconductor wafer (object) W by electrostatic attraction. The electrostatic chuck 1 is used, for example, to fix the semiconductor wafer W in a vacuum chamber of a semiconductor manufacturing device. FIG. 1 is a schematic perspective view of the electrostatic chuck 1 of the first embodiment. As shown in FIG. 1, the electrostatic chuck 1 includes a plate-shaped member 10, a base member 20, and a bonding layer 30 that bonds the plate-shaped member 10 and the base member 20 together.

[0016] 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 corresponds to the vertical direction (thickness direction) of the electrostatic chuck 1, and the X and Y axes correspond to the radial directions of the electrostatic chuck 1.

[0017] As shown in Fig. 1, the plate-like member 10 is a disk-shaped member made of ceramic. There are no particular limitations on the ceramic material as long as it does not impair the object of the present invention, but from the viewpoints of strength, wear resistance, plasma resistance, etc., it is preferable to use a ceramic material whose main component is aluminum oxide (alumina, Al2O3) or aluminum nitride (AlN). Note that the main component here means the component with the largest content (for example, a component with a volume content of 90% or more by volume).

[0018] The diameter of the plate-shaped member 10 is, for example, about 150 mm to 300 mm, and the thickness of the plate-shaped member 10 is, for example, about 2 mm to 6 mm.

[0019] Fig. 2 is a cross-sectional view schematically illustrating the internal structure of the electrostatic chuck 1 of embodiment 1. Fig. 2 shows a cross section of the electrostatic chuck 1 cut in the vertical direction (Z-axis direction). As shown in Figs. 1 and 2, the plate-like member 10 has a holding surface (upper surface) 11 that holds the semiconductor wafer W, and a lower surface 12 that is disposed on the opposite side of the holding surface 11.

[0020] The holding surface 11 of the plate-like member 10 has an uneven shape. Specifically, the holding surface 11 has an annular seal band 13 formed near its outer edge, and a plurality of protrusions (mesas) 14 provided independently inside the seal band 13. The seal band 13 and the protrusions 14 are each provided in a shape that protrudes upward from a flat reference surface 111. The reference surface 111 is formed by the upper surface of a plate-like (disk-like) base 100 that constitutes the plate-like member 10.

[0021] 3 is a top view of the electrostatic chuck 1 of the first embodiment. As shown in FIG. 3, the seal band 13 is provided so as to surround a plurality of protrusions 14. As shown in FIG. 2, the cross section (XZ cross section) of the seal band 13 has a substantially rectangular shape. The height (height from the reference surface 111) of the seal band 13 and the height (height from the reference surface 111) of the protrusions 14 are substantially equal to each other, and are, for example, about 10 μm to 20 μm. Furthermore, when viewed in plan from the holding surface 11 side, the width of the seal band 13 is about 0.5 mm to 5.0 mm.

[0022] The multiple protrusions 14 are arranged so as to be evenly dispersed and spaced apart from one another on the reference surface 111. In a plan view, the protrusions 14 of this embodiment include an opening 141 disposed at the center and a peripheral wall 142 disposed around the opening 141. Details of the protrusions 14 will be described later.

[0023] The semiconductor wafer W is supported by a seal band 13 and a plurality of protrusions 14 on the holding surface 11 of the plate-like member 10 and is held by the electrostatic chuck 1. When the semiconductor wafer W is held by the electrostatic chuck 1, a space S is formed between the lower surface of the semiconductor wafer W and a reference surface 111 of the plate-like member 10. An inert gas (e.g., helium gas) is supplied to this space S through a plurality of gas holes (not shown) provided in the reference surface 111 of the plate-like member 10.

[0024] 2, the plate-like member 10 is provided with an electrode 16. The electrode 16 is provided with at least one of an attraction electrode, a heater electrode, and a high-frequency electrode.

[0025] 1, the base member 20 is disk-shaped (cylindrical). The base member 20 is made of a metal material such as aluminum or an aluminum alloy. However, the base member 20 may be made of a material other than a metal material.

[0026] A coolant flow path (not shown) is provided inside the base member 20. The electrostatic chuck 1 is cooled by flowing a coolant (for example, a fluorine-based inert liquid, water, or the like) through the coolant flow path.

[0027] 1 to 3, the base member 20 has an upper surface 21 and a lower surface 22 disposed on the opposite side of the upper surface 21. The upper surface 21 of the base member 20 is connected to the lower surface 12 of the plate-like member 10 via a bonding layer 30.

[0028] The diameter of the base member 20 is, for example, about 180 mm to 350 mm, and the thickness of the base member 20 (length in the Z-axis direction) is, for example, about 20 mm to 50 mm.

[0029] The bonding layer 30 is disposed between the lower surface 12 of the plate-shaped member 10 and the base member 20, and bonds the plate-shaped member 10 and the base member 20 together. The lower surface 12 of the plate-shaped member 10 and the base member 20 are thermally connected via the bonding layer 30. The bonding layer 30 is made of a synthetic resin adhesive such as a silicone resin, an acrylic resin, or an epoxy resin, but any material can be used. The thickness of the bonding layer 30 is, for example, approximately 0.1 mm to 1.0 mm.

[0030] Next, the protrusion 14 will be described in detail with reference to Fig. 4 and Fig. 5. Fig. 4 is a top view of the protrusion 14 of embodiment 1, and Fig. 5 is a cross-sectional view taken along line AA in Fig. 4. The protrusion 14 generally has a cylindrical shape that protrudes from a flat reference surface 111.

[0031] The protrusion 14 includes an opening 141 disposed on the central side and a peripheral wall portion 142 disposed around the opening 141. The opening 141 is formed of a cylindrical portion with a bottom surrounded by an inner peripheral surface 142a of the peripheral wall portion 142 and a bottom surface 144. The bottom surface 144 and the reference surface 111 may be disposed on the same plane, or the bottom surface 144 may be disposed above the reference surface 111, or the bottom surface 144 may be disposed below the reference surface 111.

[0032] The upper surface 143 of the peripheral wall portion 142 forms a continuous, unbroken circular annular surface when viewed from the reference plane 111 side. The uppermost portion of the upper surface 143, which is made up of such a circular annular surface (annular surface), is generally flat (flat surface), and this portion comes into contact with the lower surface of the semiconductor wafer (object) W. In this specification, the flat portion of the upper surface 143 that comes into contact with the semiconductor wafer (object) W is referred to as the "contact surface 143a." As shown in FIG. 4, the contact surface 143a of this embodiment forms a circular annular shape with a predetermined width when viewed from above. The width of the contact surface 143a is smaller than the thickness of the peripheral wall portion 142 (the width of the upper surface 143). The contact surface 143a forms a continuous, unbroken circular annular shape.

[0033] Note that, on the upper surface 143, between the contact surface 143a and the inner peripheral surface 142a of the peripheral wall portion 142, there is an inclined surface 143b that slopes downward from the contact surface 143a side toward the inner peripheral surface 142a side. On the upper surface 143, between the contact surface 143a and the outer peripheral surface 142b of the peripheral wall portion 143, there is an inclined surface 143c that slopes downward from the contact surface 143a side toward the outer peripheral surface 142b side. In this specification, the inclined surface 143b arranged on the inner peripheral surface 142a side may be referred to as the "inner inclined surface 143b," and the inclined surface 143c arranged on the outer peripheral surface 142b side may be referred to as the "outer inclined surface 143c."

[0034] When viewing a cross section obtained by cutting the peripheral wall portion 142 of such a convex portion 14 in the thickness direction of the plate-like member 10 (see the cross section shown in Figure 5), the upper surface 143 of the peripheral wall portion 142 has a convex shape that protrudes upward.

[0035] The height of the protrusions 14 is approximately equal to the height of the seal band 13, and is, for example, about 10 μm to 20 μm. When viewed from above from the reference surface 111 side, the size (diameter) of the protrusions 14 is about 0.5 mm to 2.0 mm.

[0036] Next, an example of a method for manufacturing the electrostatic chuck 1 will be described. First, a method for manufacturing the plate-shaped member 10 of the electrostatic chuck 1 will be described. The method for manufacturing the plate-shaped member 10 is an application of a sheet lamination method using green sheets (ceramic green sheets), and first, a first laminate is formed by laminating a plurality of green sheets. Note that a conductor layer for forming an electrode 16 is formed on a predetermined green sheet constituting the first laminate, and such a green sheet is laminated on other green sheets as appropriate.

[0037] The slurry for the green sheets can be obtained by, for example, mixing a mixture containing alumina powder, an acrylic binder, a dispersant, a plasticizer, etc., with an organic solvent added, using a ball mill. This slurry is formed into a sheet using a casting device, and then the formed product is dried to obtain multiple green sheets.

[0038] The metallization paste for forming the conductor layer can be obtained by adding conductive powder such as tungsten or molybdenum to a mixture of alumina powder, an acrylic binder, and an organic solvent, and kneading the mixture. The conductor layer can be formed on a specific green sheet by printing the metallization paste using, for example, a screen printing device.

[0039] Next, holes and grooves for forming flow paths for the inert gas are formed in predetermined locations of the first laminate using a known processing device (router, etc.). When a porous body is formed in part of the flow path, a paste for forming the porous body is appropriately filled into the holes for the flow path. The paste for the porous body can be obtained, for example, by kneading a mixture containing alumina powder, a pore-forming material, a binder, an organic solvent, etc. Methods for filling the holes with the paste for the porous body include, for example, a method using an injection molding device and a method using a screen printing device. After the holes and the like are formed in this way, the first laminate is appropriately dried.

[0040] The first laminate is then stacked with a second laminate prepared separately. The second laminate is made of a plurality of green sheets stacked together. The second laminate also has holes or the like for forming a flow path for an inert gas. The laminate made of the first and second laminates is made of, for example, a stack of 20 green sheets, which are thermocompression bonded together. The outer periphery of this laminate may be cut as appropriate. The laminate is then machined to produce a disk-shaped compact. The resulting compact is then degreased and fired, and the degreased and fired compact is then fired (main firing) to obtain a fired body. This fired body is referred to as a "ceramic member" in this specification.

[0041] The ceramic member manufactured in this manner and a separately manufactured base member 20 are bonded together using an adhesive for the bonding layer 30. The manufacturing method for the base member 20 is the same as that for the conventional product. The bonding between the ceramic member and the base member 20 using an adhesive is the same as that for the conventional product. Therefore, detailed explanations thereof will be omitted.

[0042] The surface of the ceramic member 101 bonded to the base member 20 in this manner is processed to form the seal band 13 and the protrusions 14. Here, with reference to FIG. 6, a method of processing the surface of the ceramic member 101 to form the protrusions 14 will be described. FIG. 6 is an explanatory diagram that schematically shows a method of processing the surface of the ceramic member 101 to form the protrusions 14. Note that FIG. 6 also schematically shows a cross-sectional configuration obtained by cutting the ceramic member 101 in the thickness direction. For ease of explanation, the base member 20 and the like are omitted from FIG. 6.

[0043] FIG. 6(A) is an explanatory diagram showing a state in which resist masks 40 are placed at predetermined locations on the surface 101a of the ceramic member 101. As shown in FIG. 6(A), the resist masks 40 are placed at predetermined locations on the surface 101a of the ceramic member 101 where the plurality of protrusions 14 will be formed. The resist masks 40 have a shape corresponding to the shape of the protrusions 14 when viewed from above. Specifically, the resist mask 40 has a seamless, continuous ring shape when viewed from above. A circular opening 41 is provided in the center of the resist mask 40. A known resist mask for blast processing is used as the resist mask 40. A resist mask (not shown) for forming the seal band 13 is placed on the outer edge of the surface 101a of the ceramic member 101.

[0044] FIG. 6(B) is an explanatory diagram showing the state after blasting the surface 101a of the ceramic member 101. As shown in FIG. 6(B), when blasting (e.g., shot blasting in which ceramic particles or the like are projected) is performed from above toward the surface 101a of the ceramic member 101, the ceramic member 101 is scraped in areas not covered by the resist mask 40. At this time, the area corresponding to the central opening 41 of the resist mask 40 is scraped by the blasting. In contrast, the ceramic member 101 in areas covered by the resist mask 40 is protected by the resist mask 40 and remains unscraped by the blasting. As a result, a cylindrical peripheral wall portion 142, which will become the protrusion 14, is obtained in a raised shape from the surface 101a of the ceramic member 101. An opening 141 is formed inside the peripheral wall portion 142.

[0045] Fig. 6(C) is an explanatory diagram showing a state in which the resist mask 40 has been removed from the upper surface of the peripheral wall portion 142 of the ceramic member 101. After the blasting process, when a chemical solution for removing the resist mask 40 is applied to the resist mask 4, the resist mask 4 is removed from the upper surface of the peripheral wall portion 142, as shown in Fig. 6(C). Note that the upper surface of the peripheral wall portion 142 in this state is generally flat.

[0046] FIG. 6(D) is an explanatory diagram showing a state in which the upper surface 143 of the peripheral wall portion 142 has been mirror-polished. After the resist mask 40 is removed, the surface 101a of the ceramic portion 101 (including the upper surface 143 of the peripheral wall portion 142) is mirror-polished, forming a plurality of height-adjusted protrusions 14 on the reference surface 111 of the base portion 100. By mirror-polishing the upper surface 143 of the protrusions 14 (peripheral wall portion 142), the outer peripheral edge and inner peripheral edge of the annular upper surface 143 of the peripheral wall portion 142 are each rounded (outer inclined surface 143c, inner inclined surface 143b). The portion located between them becomes a flat contact surface 143a that comes into contact with the semiconductor wafer (object) W. As described above, the surface 101a of the ceramic member 101 is processed to form the convex portions 14, thereby obtaining a plate-shaped member 10 having a base 100 and a plurality of convex portions 14 formed on the reference surface 111 of the base 100.

[0047] As described above, in the electrostatic chuck 1 of this embodiment, the upper surfaces 143 of the protrusions 14 have contact surfaces 143a that are flat, continuous, and unbroken circular annular surfaces that come into contact with the semiconductor wafer (object) W. Therefore, the area over which each of the protrusions 14 comes into contact with the underside of the semiconductor wafer W is larger than that of conventional protrusions. Therefore, when the semiconductor wafer (object) W is held, application of a large local force to the upper surfaces 143 (contact surfaces 143A) of the protrusions 14 is suppressed. Therefore, in the electrostatic chuck 1 of this embodiment, generation of particles (missing particles) from the upper surfaces 143 of the protrusions 14 is suppressed.

[0048] <Embodiment 2> Next, the protrusions 14A of the plate-shaped member 10A included in the electrostatic chuck according to the second embodiment will be described with reference to FIG. 7. FIG. 7 is a top view of the protrusions 14A of the second embodiment. The basic configuration of the electrostatic chuck of the present embodiment is similar to that of the first embodiment, and a plurality of protrusions 14A are provided on the top surface of the plate-shaped member 10A. However, the shape of the protrusions 14A of the present embodiment is different from that of the first embodiment, as will be described below.

[0049] The protrusion 14A has an overall shape that rises from a flat reference surface 111A. The protrusion 14A includes an opening 141A disposed in the center and a peripheral wall 142A disposed around the opening 141A. As shown in FIG. 7, the peripheral wall 142A has a discontinuous annular shape including a single slit 15A when viewed in plan from the reference surface 111A side. The opening 141A is formed by a cylindrical portion with a bottom and a single slit that is surrounded by an inner circumferential surface 142Aa of the peripheral wall 142A and a bottom surface 144A.

[0050] The upper surface 143A of the peripheral wall portion 142A forms a discontinuous circular annular surface including a single gap when viewed from the reference plane 111A side. The uppermost portion of the upper surface 143A, which is made up of such a discontinuous circular annular surface, is generally flat (flat surface), and this portion comes into contact with the underside of the semiconductor wafer (object). This flat portion is the contact surface 143Aa of the upper surface 143A. As shown in FIG. 7, the contact surface 143Aa forms a discontinuous circular annular surface including a single gap having a predetermined width when viewed in plan.

[0051] The upper surface 143A has an inclined surface 143Ab (inner inclined surface 143Ab) between the contact surface 143Aa and the inner peripheral surface 142Aa of the peripheral wall portion 143A, which is inclined downward from the contact surface 143Aa side toward the inner peripheral surface 142Aa side. The upper surface 143A has an inclined surface 143Ac (outer inclined surface 143Ac) between the contact surface 143Aa and the outer peripheral surface 142Ab of the peripheral wall portion 143A, which is inclined downward from the contact surface 143Aa side toward the outer peripheral surface 142Ab side. The height of the protrusion 14A is the same as in the first embodiment.

[0052] Furthermore, when viewing a cross section obtained by cutting the peripheral wall portion 142A of the protrusion 14A in the thickness direction of the plate-shaped member 10A, the upper surface 143A of the peripheral wall portion 142A has a convex shape that protrudes upward, similar to embodiment 1.

[0053] The electrostatic chuck of this embodiment holds a semiconductor wafer with the underside of the semiconductor wafer supported by the contact surfaces 143Aa of the multiple protrusions 14A. In this embodiment, the upper surfaces 143A of the protrusions 14A have contact surfaces 143Aa that are flat, discontinuous circular annular surfaces including a single gap, which contact the semiconductor wafer. This increases the contact area of each protrusion 14A with the underside of the semiconductor wafer compared to conventional protrusions. Therefore, in this embodiment as well, when holding a semiconductor wafer (object) W, application of a large localized force to the upper surfaces 143A (contact surfaces 143Aa) of the protrusions 14A is suppressed.

[0054] In the electrostatic chuck of this embodiment, an inert gas is supplied to the space formed between the lower surface of the semiconductor wafer and the reference surface 111A of the plate-shaped member 10A through a plurality of gas holes (not shown) provided in the reference surface 111A, as in the first embodiment. As described above, the protrusion 14A of this embodiment has a slit 15A provided in the peripheral wall 142A, and the slit 15A connects the space within the opening 141A of the protrusion 14A to the space outside the peripheral wall 142A. That is, in this embodiment, the space outside the protrusion 14A (peripheral wall 142A) to which the inert gas is supplied is connected to the space within the opening 141A of the protrusion 14A through the slit 15A. Therefore, in this embodiment, when the electrostatic chuck holds a semiconductor wafer, the protrusion 14A has a structure that makes it easy to reliably supply an inert gas to the space within the opening 14A.

[0055] <Embodiment 3> Next, the protrusions 14B of the plate-shaped member 10B included in the electrostatic chuck according to the third embodiment will be described with reference to FIG. 8. FIG. 8 is a top view of the protrusions 14B of the third embodiment. The basic configuration of the electrostatic chuck of the present embodiment is similar to that of the first embodiment, and a plurality of protrusions 14B are provided on the top surface of the plate-shaped member 10B. However, the shape of the protrusions 14B of the present embodiment is different from that of the first embodiment, as will be described below.

[0056] The protrusion 14B generally has a shape that rises from the flat reference surface 111B. The protrusion 14B includes an opening 141B disposed in the center and a set (two) of peripheral wall portions 142B disposed around the opening 141B. One of the set of peripheral wall portions 142B may be referred to as the "peripheral wall portion 142B1" and the other as the "peripheral wall portion 142B2."

[0057] 8, when viewed in plan from the reference surface 111B side, the peripheral wall portion 142B has a discontinuous annular shape including two (one example of a plurality of) gaps 15B (15B1, 15B2). The opening 141B is made up of a cylindrical portion with a bottom and two gaps that is surrounded by the inner peripheral surfaces 142Ba of the pair of peripheral wall portions 142B and the bottom surface 144B.

[0058] When viewed in a plan view from the reference plane 111B side, the upper surface 143B of one pair of peripheral wall portions 142B forms a discontinuous circular annular surface including two (one example of multiple) gaps. Of the upper surfaces 143B formed from such discontinuous circular annular surfaces, the uppermost portion of the upper surface 143B1 of one peripheral wall portion 142B1 is generally flat (flat surface), and this portion serves as a contact surface 143Ba that comes into contact with the underside of a semiconductor wafer (object). Of the upper surfaces 143B formed from discontinuous circular annular surfaces, the uppermost portion of the upper surface 143B2 of the other peripheral wall portion 142B2 is generally flat (flat surface), and this portion serves as a contact surface 143Ba that comes into contact with the underside of a semiconductor wafer (object). That is, in this embodiment, the two contact surfaces 143Ba, as shown in FIG. 8, form a discontinuous annular shape including two gaps with a predetermined width in plan view as a whole.

[0059] The upper surface 143B1 of one of the peripheral walls 142B1 has an inclined surface 143Bb (inner inclined surface 143Bb) that slopes downward from the contact surface 143Ba toward the inner peripheral surface 142Ba between the contact surface 143Ba and the inner peripheral surface 142Ba of the peripheral wall 142B1. The upper surface 143B1 has an inclined surface 143Bc (outer inclined surface 143Bc) that slopes downward from the contact surface 143Ba toward the outer peripheral surface 143Bb between the contact surface 143Ba and the outer peripheral surface 142Bb of the peripheral wall 142B1.

[0060] Similarly, the upper surface 143B2 of the other peripheral wall portion 142B2 has an inclined surface 143Bb (inner inclined surface 143Bb) arranged on the inner peripheral surface 142Ba side and an inclined surface 143Bc (outer inclined surface 143Bc) arranged on the outer peripheral surface 142Bb side, with the contact surface 143Ba therebetween. The height of the protrusion 14B (the height of each peripheral wall portion 142B) is the same as in the first embodiment.

[0061] Furthermore, when viewing a cross section obtained by cutting the peripheral wall portion 142B (142B1, 142B2) of the convex portion 14B in the thickness direction of the plate-shaped member 10B, each upper surface 143B (143B1, 143B2) of the peripheral wall portion 142B (142B1, 142B2) has a convex shape that protrudes upward, as in embodiment 1.

[0062] The electrostatic chuck of this embodiment holds a semiconductor wafer with the underside of the semiconductor wafer supported by the contact surfaces 143Ba of the multiple protrusions 14B. In this embodiment, the upper surfaces 143B of the protrusions 14B have contact surfaces 143Ba that are flat, discontinuous circular annular surfaces including two gaps, which contact the semiconductor wafer. This increases the area over which each protrusion 14B contacts the underside of the semiconductor wafer compared to conventional protrusions. Therefore, in this embodiment as well, when holding a semiconductor wafer (object) W, application of a large localized force to the upper surfaces 143B (contact surfaces 143Ba) of the protrusions 14B is suppressed.

[0063] In the electrostatic chuck of this embodiment, as in the first embodiment, an inert gas is supplied to the space formed between the lower surface of the semiconductor wafer and the reference surface 111B of the plate-shaped member 10B through a plurality of gas holes (not shown) provided in the reference surface 111B. As described above, the protrusion 14B of this embodiment has two slits 15B provided in the peripheral wall 142B, and these slits 15B connect the space within the opening 141B of the protrusion 14B to the space outside the peripheral wall 142B. That is, in this embodiment, the space outside the protrusion 14B (peripheral wall 142B) to which the inert gas is supplied is connected to the space within the opening 141B of the protrusion 14B through the slit 15B. Therefore, in this embodiment, when the electrostatic chuck holds a semiconductor wafer, the protrusion 14B has a structure that makes it easy to reliably supply the inert gas to the space within the opening 14B.

[0064] <Embodiment 4> Next, the protrusions 14C of the plate-shaped member 10C included in the electrostatic chuck according to the fourth embodiment will be described with reference to FIG. 9. FIG. 9 is a top view of the protrusions 14C of the fourth embodiment. The basic configuration of the electrostatic chuck of the present embodiment is similar to that of the first embodiment, and a plurality of protrusions 14C are provided on the top surface of the plate-shaped member 10C. However, the shape of the protrusions 14C of the present embodiment is different from that of the first embodiment, as will be described below.

[0065] As in the first embodiment, the protrusion 14C generally has a cylindrical shape that protrudes from the flat reference surface 111C. The protrusion 14C includes an opening 141C disposed in the center and a cylindrical peripheral wall 142C disposed around the opening 141C. As shown in FIG. 9, the peripheral wall 142C has a continuous, unbroken ring shape when viewed in plan from the reference surface 111C side. The opening 141C is a cylindrical portion with a bottom that is surrounded by an inner circumferential surface 142Ca of the peripheral wall 142C and a bottom surface 144C.

[0066] The upper surface 143C of the peripheral wall portion 142C forms a continuous, unbroken circular annular surface when viewed from the reference surface 111C side. The uppermost portion of the upper surface 143C, which is a circular annular surface, is generally flat (flat surface), and this portion comes into contact with the underside of the semiconductor wafer (object). This flat portion is the contact surface 143Ca of the upper surface 143C. As shown in FIG. 9, the contact surface 143Ca forms a circular annular shape with a predetermined width when viewed from above.

[0067] The upper surface 143C has an inclined surface 143Cb (inner inclined surface 143Cb) between the contact surface 143Ca and the inner peripheral surface 142Ca of the peripheral wall portion 143C, which is inclined downward from the contact surface 143Ca side toward the inner peripheral surface 142Ca side. The upper surface 143C has an inclined surface 143Cc (outer inclined surface 143Cc) between the contact surface 143Ca and the outer peripheral surface 142Cb of the peripheral wall portion 143C, which is inclined downward from the contact surface 143Ca side toward the outer peripheral surface 142Cb side. The height of the protrusion 14C is the same as in the first embodiment.

[0068] Furthermore, when viewing a cross section obtained by cutting the peripheral wall portion 142C of the protrusion 14C in the thickness direction of the plate-shaped member 10C, the upper surface 143C of the peripheral wall portion 142C has a convex shape that protrudes upward, similar to embodiment 1.

[0069] In this embodiment, in plan view from the reference surface 111C side, the width L2 of the upper surface (annular surface) 143C is larger than the opening radius L2 of the opening 141C.

[0070] The electrostatic chuck of this embodiment holds a semiconductor wafer with the underside of the semiconductor wafer supported by the contact surfaces 143Ca of the plurality of protrusions 14C. In this embodiment, the upper surfaces 143C of the protrusions 14C are provided with the contact surfaces 143Ca that are flat, circular annular surfaces that come into contact with the semiconductor wafer, so that the area over which each of the protrusions 14C comes into contact with the underside of the semiconductor wafer is larger than that of conventional protrusions.

[0071] Moreover, in this embodiment, as described above, the width L2 of the upper surface (annular surface) 143C is larger than the opening radius L2 of the opening 141C, so it is easy to ensure a large width for the contact surface 143Ca formed on the upper surface (annular surface) 143C.

[0072] Therefore, in this embodiment, when the semiconductor wafer (object) W is held, application of a particularly large force locally to the upper surface 143C (contact surface 143Ca) of the protrusion 14C is suppressed.

[0073] <Embodiment 5> Next, the convex portions 14D of a plate-shaped member 10D included in an electrostatic chuck according to embodiment 5 will be described with reference to FIG. 10. FIG. 10 is a top view of the convex portions 14D of embodiment 5. The basic configuration of the electrostatic chuck of this embodiment is similar to that of embodiment 1, and a plurality of convex portions 14D are provided on the top surface of the plate-shaped member 10D. However, the shape of the convex portions 14D of this embodiment is different from that of embodiment 1 and is rectangular in plan view, as will be described below.

[0074] As in the first embodiment, the protrusion 14D generally has a cylindrical shape that protrudes from a flat reference surface 111D. The protrusion 14D includes an opening 141D disposed in the center and a cylindrical peripheral wall 142D disposed around the opening 141D. As shown in FIG. 10 , the peripheral wall 142D forms a continuous, unbroken, rectangular ring shape (a rectangular frame shape) when viewed from above from the reference surface 111D side. The opening 141D has a rectangular shape in plan view and is composed of a cylindrical portion with a bottom that is surrounded by an inner peripheral surface 142Da of the peripheral wall 142D and a bottom surface 144D.

[0075] The upper surface 143D of the peripheral wall portion 142D forms a continuous, unbroken, rectangular ring-shaped surface when viewed from the reference surface 111D side. The uppermost portion of the upper surface 143D, which is made up of such a rectangular ring-shaped surface, is generally flat (flat surface), and this portion comes into contact with the underside of the semiconductor wafer (object). This flat portion is the contact surface 143Da of the upper surface 143D. As shown in FIG. 10 , the contact surface 143Da forms a rectangular ring-shaped (rectangular frame-shaped) having a predetermined width when viewed in plan.

[0076] The upper surface 143D has an inclined surface 143Db (inner inclined surface 143Db) between the contact surface 143Da and the inner peripheral surface 142Da of the peripheral wall portion 143D, which is inclined downward from the contact surface 143Da side toward the inner peripheral surface 142Da side. The upper surface 143D has an inclined surface 143Dc (outer inclined surface 143Dc) between the contact surface 143Da and the outer peripheral surface 142Db of the peripheral wall portion 143D, which is inclined downward from the contact surface 143Da side toward the outer peripheral surface 142Db side. The height of the protrusion 14D is the same as in the first embodiment.

[0077] Furthermore, when viewing a cross section obtained by cutting the peripheral wall portion 142D of the convex portion 14D in the thickness direction of the plate-shaped member 10D, the upper surface 143D of the peripheral wall portion 142D has a convex shape that protrudes upward, similar to embodiment 1.

[0078] The electrostatic chuck of this embodiment holds a semiconductor wafer with the underside of the semiconductor wafer supported by the contact surfaces 143Da of the plurality of protrusions 14D. In this embodiment, the upper surfaces 143D of the protrusions 14D have contact surfaces 143Da that are flat, rectangular annular surfaces that contact the semiconductor wafer. This increases the area over which each protrusion 14D contacts the underside of the semiconductor wafer compared to conventional protrusions. Therefore, in this embodiment, when holding a semiconductor wafer (object) W, application of a particularly large force to the upper surfaces 143C (contact surfaces 143Ca) of the protrusions 14C is suppressed.

[0079] As described above, the peripheral wall portion 143D (upper surface 143D, contact surface 143Ca) of the protrusion 14D may be formed to have a quadrangular shape in a plan view.

[0080] <Embodiment 6> Next, the protrusions 14E of a plate-shaped member 10E included in an electrostatic chuck according to a sixth embodiment will be described with reference to Fig. 11. Fig. 11 is a top view of the protrusions 14E of the sixth embodiment. The basic configuration of the electrostatic chuck of this embodiment is similar to that of the first embodiment, and a plurality of protrusions 14E are provided on the top surface of the plate-shaped member 10E. However, the shape of the protrusions 14E of this embodiment is different from that of the first embodiment, and is elliptical in plan view, as will be described below.

[0081] As in the first embodiment, the protrusion 14E generally has a cylindrical shape that protrudes from a flat reference surface 111E. The protrusion 14E includes an opening 141E disposed in the center and a cylindrical peripheral wall 142E disposed around the opening 141E. As shown in FIG. 11 , the peripheral wall 142E forms a continuous, unbroken elliptical ring (elliptical frame) when viewed from above from the reference surface 111E side. The opening 141E has an elliptical shape in a planar view and is composed of a cylindrical portion with a bottom that is surrounded by an inner peripheral surface 142Ea of the peripheral wall 142E and a bottom surface 144E.

[0082] The upper surface 143E of the peripheral wall portion 142E forms a continuous, unbroken elliptical ring-shaped surface when viewed in a plan view from the reference surface 111E side. The uppermost portion of the upper surface 143E, which is an elliptical ring-shaped surface, is generally flat (flat surface), and this portion comes into contact with the underside of the semiconductor wafer (object). This flat portion is the contact surface 143Ea of the upper surface 143E. As shown in FIG. 11 , the contact surface 143Ea forms an elliptical ring (a rectangular frame shape) with a predetermined width when viewed in a plan view.

[0083] The upper surface 143E has an inclined surface 143Eb (inner inclined surface 143Eb) between the contact surface 143Ea and the inner peripheral surface 142Ea of the peripheral wall portion 143E, which slopes downward from the contact surface 143Ea side toward the inner peripheral surface 142Ea side. The upper surface 143E has an inclined surface 143Ec (outer inclined surface 143Ec) between the contact surface 143Ea and the outer peripheral surface 142Eb of the peripheral wall portion 143E, which slopes downward from the contact surface 143Ea side toward the outer peripheral surface 142Eb side. The height of the protrusion 14E is the same as in the first embodiment.

[0084] Furthermore, when viewing a cross section obtained by cutting the peripheral wall portion 142E of the protrusion 14E in the thickness direction of the plate-shaped member 10E, the upper surface 143E of the peripheral wall portion 142E has a convex shape that protrudes upward, similar to embodiment 1.

[0085] The electrostatic chuck of this embodiment holds a semiconductor wafer with the underside of the semiconductor wafer supported by the contact surfaces 143Ea of the multiple protrusions 14E. In this embodiment, the upper surfaces 143E of the protrusions 14E have contact surfaces 143Ea that are flat, rectangular annular surfaces that contact the semiconductor wafer. This increases the area over which each protrusion 14E contacts the underside of the semiconductor wafer compared to conventional protrusions. Therefore, in this embodiment, when holding a semiconductor wafer (object) W, application of a particularly large force to the upper surfaces 143E (contact surfaces 143Ea) of the protrusions 14E is suppressed.

[0086] As described above, the peripheral wall portion 143E (upper surface 143E, contact surface 143Ea) of the protrusion 14E may be formed to have an elliptical shape in a plan view.

[0087] <Embodiment 7> Next, the protrusions 14F of a plate-shaped member 10F included in an electrostatic chuck 1F according to the seventh embodiment will be described with reference to FIG. 12. FIG. 12 is a top view of the electrostatic chuck 1F according to the seventh embodiment. The basic configuration of the electrostatic chuck 1F according to the seventh embodiment is the same as that of the first embodiment. The plate-shaped member 10F is provided so as to be stacked on the upper surface 21F side of a base member 20F. As in the first embodiment, a plurality (a large number) of protrusions 14F are provided on the holding surface 11F of the plate-shaped member 10F. As in the first embodiment, each of the protrusions 14F includes a peripheral wall 143F that protrudes cylindrically from a flat reference surface 111F and an opening 141F located at the center thereof. As in the first embodiment, a circular seal band 13F is provided near the outer edge of the holding surface 11F of the plate-shaped member 10F.

[0088] In this embodiment, the density of the plurality of protrusions 14F on the holding surface 11F, which is circular in plan view of the plate-shaped member 10F, is set so that it is higher on the outer circumferential side than on the inner circumferential side. In this way, the arrangement density of the plurality of protrusions 14F on the holding surface 11F may be set appropriately in consideration of the ease of supplying the inert gas, etc.

[0089] <Other embodiments> The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments, for example, are also included within the technical scope of the present invention.

[0090] (1) As shown in Figure 12, the surface of a plate-like member may be provided with a combination of a convex portion of the present invention including an opening on the central side (for example, convex portion 14 of embodiment 1 having opening 141 and peripheral wall portion 142) and a conventional convex portion 14P that does not include an opening. In other words, among the multiple convex portions, some may be convex portions of the present invention, and the others may be conventional convex portions. For example, among the multiple convex portions, at least the convex portions arranged in places that are likely to come into contact with the object and be scraped may be convex portions of the present invention.

[0091] (2) The size (diameter) of the protrusions of the present invention in a plan view may be set to be larger than the size (diameter) of the protrusions of conventional types in a plan view. By setting the size (diameter) to be larger in this way, it is easy to ensure a contact surface of the protrusions of the present invention on the upper surface of the protrusions.

[0092] (3) The convex portion including the opening at the center may be polygonal, such as triangular or rectangular, in plan view.

[0093] (4) The gas flow passage for passing the inert gas does not have to be formed in the base member, but may be formed only in the holding substrate.

[0094] (5) The manufacturing method of the holding device shown in the above embodiment is merely an example, and other manufacturing methods may be used as long as they do not impair the object of the present invention. [Explanation of symbols]

[0095] 1...holding device (electrostatic chuck), 10...plate-shaped member, 11...holding surface, 111...reference surface, 14...protrusion, 141...opening, 142...peripheral wall portion, 143...upper surface (annular surface), 143a...contact surface, 30...bonding layer, W...object

Claims

1. A holding device comprising a plate-like member having a base portion including a reference surface and a plurality of protrusions that protrude from the reference surface, The protrusion includes an opening disposed at a center side and a peripheral wall disposed around the opening, A holding device in which the upper surface of the peripheral wall portion forms a continuous annular surface or a discontinuous annular surface that includes a break in part when viewed in a plan view from the reference surface side.

2. The peripheral wall portion has an annular shape when viewed in plan from the reference surface side, 2. The holding device according to claim 1, wherein the upper surface of the peripheral wall portion forms an unbroken circular annular surface.

3. the peripheral wall portion has a discontinuous annular shape including one or more gaps when viewed in plan from the reference surface side, 2. The retaining device according to claim 1, wherein the upper surface of the peripheral wall portion forms a discontinuous circular annular surface including one or more discontinuities.

4. The holding device according to claim 1 , wherein a width of the annular surface is larger than an opening radius of the opening when viewed from the reference surface side.

5. 4. A holding device according to claim 1, wherein when viewed in a cross section obtained by cutting the peripheral wall portion of the convex portion in the thickness direction of the plate-shaped member, the upper surface of the peripheral wall portion has a convex shape that protrudes upward.

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