Holding member and electrostatic chuck

Abstract

To provide a technology that can improve the plasma resistance of a holding surface.SOLUTION: A holding member whose main component is ceramic and holds an object. The holding member has a holding surface that is the side that holds the object, at least a portion of the holding surface is composed of first ceramic crystal particles, and the portion inside the holding surface is composed of second ceramic crystal particles. A first particle size, which is the particle size of the first ceramic crystal particles, is smaller than a second particle size, which is the particle size of the second ceramic crystal particles.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a holding member and an electrostatic chuck. [Background technology]

[0002] As a holding member for holding an object, an electrostatic chuck that holds a wafer as the object by electrostatic attraction is known. For example, Patent Document 1 discloses an electrostatic chuck in which recesses are formed by blasting on the holding surface of a ceramic member that holds the object. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-129632 Summary of the Invention [Problem to be solved by the invention]

[0004] However, because blasting is a process that detaches crystal grains along grain boundaries, the electrostatic chuck described in Patent Document 1 may have a risk of increasing the surface roughness of the holding surface and increasing the area of ​​the grain boundaries exposed on the holding surface. Grain boundaries, which are boundaries between crystal grains, are regions where the atomic arrangement is disordered and have lower plasma resistance than the interior of crystal grains. For this reason, there is room for improvement in the plasma resistance of the holding surface of the holding member.

[0005] The present invention has been made to solve at least some of the above-mentioned problems, and aims to provide a holding member and an electrostatic chuck that can improve the plasma resistance of the holding surface. [Means for solving the problem]

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following forms. (1) According to one aspect of the present invention, there is provided a holding member, the holding member being primarily composed of ceramic and configured to hold an object, the holding member having a holding surface that is a surface on which the object is held, at least a portion of the holding surface being composed of first ceramic crystal particles, and a portion inside the holding surface being composed of second ceramic crystal particles, the first particle diameter being smaller than the second particle diameter being the particle diameter of the second ceramic crystal particles.

[0007] According to this configuration, at least a portion of the holding surface is composed of first ceramic crystal particles, and a portion of the holding member that is inward from the holding surface is composed of second ceramic crystal particles. The first particle diameter of the first ceramic crystal particles is smaller than the second particle diameter of the second ceramic crystal particles. Therefore, since at least a portion of the holding surface is composed of first ceramic crystal particles having a first particle diameter smaller than the second particle diameter, the size of particles generated from the holding surface during use of the holding member can be reduced. Furthermore, since the first ceramic crystal particles correspond to ceramic crystal particles that are formed by partially scraping off the second ceramic crystal particles, the surface composed of the first ceramic crystal particles includes ceramic crystal particles that expose their inner grains (portions of the crystal particles that are inward from the grain boundaries) toward the surface. In other words, since fewer grain boundaries are exposed on such surfaces, the plasma resistance of the holding surface including such surfaces can be improved.

[0008] (2) In the holding member of the above aspect, the holding surface may have a convex portion and a concave portion formed thereon, and the front surface may be a bottom surface that defines the concave portion. According to this configuration, the bottom surface defining the recess is made of the first ceramic crystal grains, which reduces the size of particles generated from the holding surface when the holding member holds an object and an inert gas flows between the object and the recess.

[0009] (3) In the holding member of the above embodiment, the surface may be a laser-processed surface. According to this configuration, the laser-processed surface is a surface in which each crystal grain is finely removed from the grain boundary toward the grain interior, so the first particle diameter of the first ceramic crystal grains is smaller than the second particle diameter. Therefore, a holding member having a first particle diameter smaller than the second particle diameter can be accurately provided. Furthermore, compared to a blast-processed surface in which blasting is performed to remove crystal grains along the grain boundaries, the laser-processed surface can have a smaller surface roughness. In other words, the increase in surface area due to surface roughness can be reduced. As a result, the surface area eroded by plasma is reduced, thereby suppressing the generation of particles due to plasma erosion.

[0010] (4) According to another aspect of the present invention, there is provided an electrostatic chuck, comprising: the holding member according to the above aspect; and an electrostatic electrode that generates an electrostatic attractive force on the holding surface. According to this configuration, when power is supplied to the electrostatic electrode, an electrostatic attraction (adsorption force) is generated, and the object can be held by this electrostatic attraction force toward the holding surface. In addition, since the first particle diameter is smaller than the second particle diameter, it is possible to provide an electrostatic chuck with improved plasma resistance while reducing the size of particles generated from the holding surface during use of the holding member.

[0011] The present invention can be realized in various forms, for example, in the form of a holding member, an electrostatic chuck, a vacuum chuck, a ceramic heater, a semiconductor manufacturing apparatus, a component including any of these, and a manufacturing method for these. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is an explanatory view schematically illustrating a cross-sectional configuration of an electrostatic chuck according to a first embodiment. [Figure 2] 10A to 10C are explanatory views showing a process of forming a recessed portion. [Figure 3] FIG. 2 is a schematic diagram showing the shape of a ceramic crystal grain. [Figure 4] FIG. 10 is an explanatory view schematically showing a cross-sectional configuration of an electrostatic chuck according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] First Embodiment FIG. 1 is an explanatory diagram schematically illustrating a cross-sectional configuration of an electrostatic chuck 1 according to a first embodiment. The electrostatic chuck 1 is a device that attracts and holds a semiconductor wafer W, which is an object, by electrostatic attraction. The arrows in FIG. 1 indicate the direction in which the semiconductor wafer W is attracted to the electrostatic chuck 1. The electrostatic chuck 1 is used, for example, to fix the semiconductor wafer W in a vacuum chamber of a semiconductor manufacturing device. The electrostatic chuck 1 includes a holding member 10 and an electrostatic electrode 30.

[0014] The holding member 10 is a disk-shaped member formed primarily of ceramic. The term "main component" refers to the component with the highest volume content. Examples of materials constituting the holding member 10 include aluminum oxide (alumina) and aluminum nitride, and in this embodiment, the holding member 10 is alumina. In this embodiment, the holding member 10 is formed from a single member made of ceramic material. The holding member 10 has a holding surface 10f and a back surface 10b. The holding surface 10f is a circular surface on the side that holds the semiconductor wafer W. The back surface 10b is a circular surface located opposite the holding surface 10f.

[0015] The holding surface 10f is formed with an annular convex portion 12, a plurality of convex portions 14, and a plurality of concave portions 16. The annular convex portion 12 is formed along the outer edge of the holding surface 10f. Each of the convex portions 14 is formed inside the annular convex portion 12. Each of the concave portions 16 is formed between the convex portions 14. In other words, the concave portions 16 are formed at positions inside the annular convex portion 12 where no convex portion 14 is formed. In this embodiment, when the holding surface 10f is viewed from a direction facing the holding surface 10f (when viewed from above), the concave portions 16 are arranged in a scattered manner on the circular holding surface 10f, and the proportion of the concave portions 16 in the holding surface 10f is 90% or more.

[0016] A plurality of through-flow channels 22 are formed inside the holding member 10. Each of the through-flow channels 22 is a channel that penetrates between the holding surface 10f and the back surface 10b, and is a channel for supplying an inert gas such as helium gas supplied from the back surface 10b side to the holding surface 10f side. The through-flow channels 22 are connected to the recess 16 on the holding surface 10f side.

[0017] The electrostatic electrode 30 is a disk-shaped member provided inside the holding member 10 and is made of a conductive material such as tungsten or molybdenum. When power is supplied from an external power source (not shown), the electrostatic electrode 30 generates an electrostatic attractive force on the holding surface 10f. The semiconductor wafer W is attracted toward the holding surface 10f by this electrostatic attractive force and is thereby held on the holding surface 10f.

[0018] When electrostatic attraction is generated on the holding surface 10f, the semiconductor wafer W comes into contact with the annular protrusion 12 and the protrusion 14, thereby being held on the holding surface 10f. With the semiconductor wafer W held on the holding surface 10f in this manner, an inert gas is supplied between the semiconductor wafer W and the holding surface 10f to increase thermal conductivity between the semiconductor wafer W and the holding surface 10f. More specifically, the inert gas is supplied from the rear surface 10b side through the through-flow passage 22 and from the recess 16 to the holding surface 10f side. The inert gas supplied to the holding surface 10f side flows through the space between the semiconductor wafer W and the recess 16 and diffuses throughout the space.

[0019] 2(A) and 2(B) are explanatory diagrams showing the process of forming the recesses 16. FIG. 2(A) shows a portion of a ceramic member 10p that forms the base of the holding member 10. The ceramic member 10p has a processing target surface 10fp. The processing target surface 10fp is the surface that becomes the holding surface 10f in the holding member 10 of FIG. 1, and corresponds to the holding surface 10f before the annular protrusion 12, the multiple protrusions 14, and the multiple recesses 16 are formed. Each recess 16 is formed in the recess formation region (not shown) of the processing target surface 10fp by laser processing. Laser processing is a process in which a laser is irradiated toward the processing target. The arrows in FIG. 2(A) indicate the laser that is irradiated during laser processing. As a result of the formation of the multiple recesses 16, as shown in FIG. 2(B) described below, the recesses 16 are formed in the recess formation region, and the portions adjacent to each recess 16 become the annular protrusion 12 and the multiple protrusions 14. During actual laser processing, the recess formation region is irradiated with laser.

[0020] The laser used for laser processing is preferably an ultrashort pulse laser. The ultrashort pulse laser has a pulse width in the femtosecond range (10- 15 ) to picosecond range (10- 10 ) and has a high energy density. When this ultrashort pulse laser is used to process the recess 16, the pulse width is shorter than the time it takes for heat to diffuse from the laser-irradiated processing target area, and the material that makes up the processing target area is instantly vaporized before the heat is transmitted to the surrounding area, making it possible to perform precise processing with little thermal impact.

[0021] 2(B) shows a portion of the holding member 10. The recess 16 has a side surface 16S and a bottom surface 16B. The side surface 16S is a surface that defines the side of the recess 16. The bottom surface 16B is a surface that defines the bottom of the recess 16. In other words, the side surface 16S and the bottom surface 16B define the recess 16. As described above, the recess 16 is formed by laser processing, and therefore, of the side surface 16S and the bottom surface 16B, at least the bottom surface 16B corresponds to the laser-processed surface.

[0022] 3(A) to 3(C) are schematic diagrams showing the shape of ceramic crystal particles. FIG. 3(A) shows the shape of ceramic crystal particles constituting the vicinity of the processing target surface 10fp. Each line defining crystal particles P1 to P4 represents a grain boundary. FIG. 3(B) shows the shape of ceramic crystal particles when blasting is performed on the processing target surface 10fp shown in FIG. 3(A). Blasting is a process in which an abrasive is projected toward the processing target. The processed surface 10fb in FIG. 3(B) is the surface exposed when the processing target surface 10fp is removed by blasting. FIG. 3(C) shows the shape of ceramic crystal particles when laser processing is performed on the processing target surface 10fp shown in FIG. 3(A). The processed surface 10fc in FIG. 3(C) is the surface exposed when the processing target surface 10fp is removed by laser processing. In FIGS. 3(A) to 3(C), the processing target surface 10fp, the processed surface 10fb, and the processed surface 10fc are indicated by thick lines.

[0023] Using Figures 3(A) to 3(C), we will explain how the particle size of the ceramic crystal grains that make up the processed surface 10fp varies depending on the type of processing performed on the processed surface 10fp. In Figure 3(B), the exposed portion Eb of the processed surface 10fb is a portion where the grain boundaries are exposed due to the detachment of crystal particles P1 and P2 during blasting of the processed surface 10fp. Blasting involves projecting an abrasive to detach crystal particles along the grain boundaries, which tends to increase the surface roughness of the processed surface 10fb and increase the area of ​​the grain boundaries exposed on the processed surface 10fb, as shown in Figure 3(B). On the other hand, in Figure 3(C), the exposed portion Ec of the processed surface 10fc is a portion where the grain interior (the portion inside the grain boundaries) is exposed due to the removal of some of the crystal particles P1 and P2 during laser processing of the processed surface 10fp. Crystal grains p1 and p2 shown in Figure 3(C) correspond to partially removed crystal grains P1 and P2. Because laser processing finely removes each crystal grain from the grain boundary toward the interior of the grain, the surface roughness of the processed surface 10fc is unlikely to increase, and the area of ​​the grain boundary exposed on the processed surface 10fc is unlikely to increase, as shown in Figure 3(C). Furthermore, because the interior of the grains is likely to be exposed on the processed surface 10fc, the grain diameter of the ceramic crystal grains that make up the surface of the processed surface 10fc is likely to be smaller than that of the processed surface 10fp and the processed surface 10fb.

[0024] As described above, the recesses 16 are formed by laser processing the processing surface 10fp, and at least the bottom surface 16B of the side surface 16S and the bottom surface 16B corresponds to the laser-processed surface. Therefore, as described with reference to FIG. 3(C), the particle diameter of the ceramic crystal grains constituting the bottom surface 16B is smaller than the particle diameter of the ceramic crystal grains constituting the portion inside the holding surface 10f (e.g., crystal grains p1 and p2 in FIG. 3(C)) because at least a portion of the grains has been removed by laser processing. In the following description, the ceramic crystal grains constituting the bottom surface 16B are referred to as first ceramic crystal grains, and the particle diameter of the first ceramic crystal grains is referred to as the first particle diameter. Furthermore, the ceramic crystal grains constituting the portion of the holding member 10 inside the holding surface 10f are referred to as second ceramic crystal grains, and the particle diameter of the second ceramic crystal grains is referred to as the second particle diameter. That is, in the holding member 10, the bottom surface 16B is a surface composed of first ceramic crystal particles, and the first particle diameter is smaller than the second particle diameter. The first ceramic crystal particles and the second ceramic crystal particles are both particles that make up the holding member 10. That is, even if a coating is applied to the holding surface 10f, the crystal particles that make up the layer formed by the coating are not considered first ceramic crystal particles. Furthermore, the first ceramic crystal particles and the second ceramic crystal particles are composed of the same ceramic material. That is, the comparison of the first particle diameter and the second particle diameter is made between crystal particles of the same material.

[0025] The fact that the first particle diameter is smaller than the second particle diameter can be confirmed by comparing the results of measuring the holding surface 10f using thin-film X-ray diffraction (thin-film XRD) with the results of measuring the interior of the holding member 10 using standard X-ray diffraction (XRD). Here, thin-film XRD is XRD in which X-rays are incident on the surface of the object to be measured at a low angle (e.g., 1° or less). XRD is XRD in which X-rays are incident toward the interior of the object to be measured. For the comparison, the values ​​of the half-width measured by thin-film XRD and XRD are used. Specifically, the fact that the first particle diameter is smaller than the second particle diameter can be confirmed by the value of the half-width measured by thin-film XRD being larger than the value of the half-width measured by XRD. Furthermore, the values ​​of the first particle diameter and the second particle diameter can be calculated from the values ​​of the half-width using Scherrer's formula, represented by the following formula (1). r=(K·λ) / βcosθ …(1) r: particle diameter, K: Scherrer constant, λ: wavelength of X-ray used for measurement, β: half-width, θ: Bragg angle

[0026] In this embodiment, the ceramic member 10p (FIG. 2(A)), which is the target of laser processing, is made of α-alumina, and therefore the portion of the holding member 10 that is inside the holding surface 10f is also made of α-alumina. On the other hand, of the side surface 16S and the bottom surface 16B, at least the vicinity of the bottom surface 16B is made of γ-alumina, which is a result of the transformation of α-alumina by the laser processing. The presence of γ-alumina is confirmed by the fact that the relative intensity is high near the peak position of γ-alumina in the XRD pattern obtained when the holding surface 10f is measured by thin-film XRD.

[0027] Furthermore, since the first ceramic crystal grains correspond to ceramic crystal grains in which portions of the second ceramic crystal grains have been removed by laser processing, among the ceramic crystal grains constituting at least the bottom surface 16B of the side surface 16S and bottom surface 16B that define the recess 16, there are ceramic crystal grains whose interiors are exposed toward the surface of the bottom surface 16B (for example, crystal grains p1 and p2 in Figure 3(C)).

[0028] Furthermore, when the cross section of the holding member 10 was observed using an SEM, multiple tiny pores (cavities) were confirmed near the bottom surface 16B. Furthermore, the shape of the ceramic crystal grains constituting the bottom surface 16B tended to be rounded compared to the bottom surface of the recess formed by blasting. Furthermore, the length of the cracks extending from the interior of the holding member 10 to the bottom surface 16B tended to be shorter compared to the bottom surface of the recess formed by blasting. Furthermore, the number of cracks extending from the interior of the holding member 10 to the bottom surface 16B tended to be fewer compared to the bottom surface of the recess formed by blasting. Furthermore, as explained in Figures 3(B) and (C), the surface roughness of the bottom surface 16B tended to be smaller compared to the bottom surface of the recess formed by blasting.

[0029] As described above, according to the holding member 10 of this embodiment, at least the bottom surface 16B of the holding surface 10f is composed of first ceramic crystal grains, and the portion inside the holding surface 10f is composed of second ceramic crystal grains. The first particle diameter, which is the particle diameter of the first ceramic crystal grains, is smaller than the second particle diameter, which is the particle diameter of the second ceramic crystal grains. Therefore, at least the bottom surface 16B of the holding surface 10f is composed of first ceramic crystal grains having a first particle diameter smaller than the second particle diameter, thereby reducing the size of particles generated from the holding surface 10f during use of the holding member 10. Furthermore, since the first ceramic crystal grains correspond to ceramic crystal grains formed by partially scraping off the second ceramic crystal grains, the bottom surface 16B composed of the first ceramic crystal grains contains ceramic crystal grains whose grain interiors (portions of the crystal grains inside the grain boundaries) are exposed toward the bottom surface 16B. In other words, fewer grain boundaries are exposed at the bottom surface 16B, thereby improving the plasma resistance of the holding surface 10f including such bottom surfaces 16B.

[0030] Furthermore, in the holding member 10 of this embodiment, the particle diameter (second particle diameter) of the ceramic crystal grains constituting the portion inside the holding surface 10f is larger than the particle diameter (first particle diameter) of the ceramic crystal grains constituting the bottom surface 16B. When the particle diameter of the crystal grains is small, there tends to be more contact between the particles, resulting in increased heat loss. In the holding member 10 of this embodiment, the particle diameter of the ceramic crystal grains constituting the portion inside the holding surface 10f is the second particle diameter, which is larger than the first particle diameter. This reduces contact between the particles in this portion, thereby reducing heat loss in this portion.

[0031] Furthermore, in the holding member 10 of this embodiment, the bottom surface 16B defining the recess 16 is made of the first ceramic crystal grains. Therefore, when the holding member 10 holds the semiconductor wafer W as an object, the size of particles generated from the holding surface 10f due to an inert gas flowing between the semiconductor wafer W and the recess 16 can be reduced.

[0032] Furthermore, in the holding member 10 of this embodiment, at least the bottom surface 16B of the side surface 16S and the bottom surface 16B corresponds to a laser-processed surface. Therefore, the bottom surface 16B, which is the laser-processed surface, is a surface obtained by finely grinding each ceramic crystal grain from the grain boundary toward the grain interior, so that the first particle diameter of the first ceramic crystal grain is smaller than the second particle diameter. This makes it possible to accurately provide a holding member 10 in which the first particle diameter is smaller than the second particle diameter. Furthermore, compared to a blast-processed surface that has been subjected to a blasting process that detaches crystal grains along the grain boundaries, the laser-processed surface can have a smaller surface roughness. In other words, the increase in surface area due to surface roughness can be minimized. As a result, the surface area eroded by plasma is reduced, thereby suppressing the generation of particles due to plasma erosion.

[0033] Furthermore, according to the electrostatic chuck 1 of the present embodiment, when power is supplied to the electrostatic electrode 30, an electrostatic attractive force (adsorption force) is generated, and the semiconductor wafer W can be held on the holding surface 10f side by this electrostatic attractive force. Furthermore, since the first particle diameter is smaller than the second particle diameter, it is possible to provide an electrostatic chuck 1 having improved plasma resistance while reducing the particle size generated from the holding surface 10f when the holding member 10 is used.

[0034] Second Embodiment 4 is an explanatory diagram schematically illustrating a cross-sectional configuration of an electrostatic chuck 1a according to the second embodiment. The electrostatic chuck 1a according to the second embodiment is the same as the electrostatic chuck 1 according to the first embodiment (see FIG. 1) except that the annular protrusion 12 does not have a protrusion 14 formed inside it.

[0035] The electrostatic chuck 1a includes a holding member 10a having a holding surface 10fa. The holding surface 10fa does not have the convex portion 14 shown in FIG. 1, but has an annular convex portion 12 and a concave portion 16a. The concave portion 16a corresponds to the entire inner portion of the annular convex portion 12 of the holding surface 10fa. When the holding surface 10fa is viewed from a direction facing the holding surface 10fa (in a plan view), the concave portion 16a is formed in a circular shape inside the annular convex portion 12. The concave portion 16a is formed by laser processing, similar to the multiple concave portions 16 shown in FIG. 1. That is, of the side surface 16aS and bottom surface 16aB defining the concave portion 16a, at least the bottom surface 16aB corresponds to a laser-processed surface. Therefore, the particle diameter (corresponding to a first particle diameter) of the ceramic crystal grains constituting the bottom surface 16aB is smaller than the particle diameter (corresponding to a second particle diameter) of the ceramic crystal grains constituting the portion inside the holding surface 10fa. In the holding member 10a of the second embodiment, the size of particles generated from the holding surface 10fa during use of the holding member 10a can also be reduced, while the plasma resistance of the holding surface 10f can be improved.

[0036] <Modification of this embodiment> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0037] In the first embodiment, the holding surface 10f is formed with the annular protrusion 12, the plurality of protrusions 14, and the plurality of recesses 16, but is not limited to this. For example, the holding surface 10f may not be formed with the annular protrusion 12, but may instead have the plurality of protrusions 14 and the plurality of recesses 16.

[0038] In the above embodiment, the holding members 10, 10a are formed with a plurality of through-flow passages 22 inside, but this is not limiting. For example, in addition to the plurality of through-flow passages 22, the holding members 10, 10a may be formed with a passage that connects the through-flow passages 22 to each other inside the holding member 10, or a passage that branches off from the passage and connects to the recess 16.

[0039] In the above embodiment, bottom surface 16B and bottom surface 16aB are composed of the first ceramic crystal particles, but this is not limited to this. The surface composed of the first ceramic crystal particles may be any surface area as long as it is at least a portion of the support surface. For example, the surface composed of the first ceramic crystal particles may be the entire support surface. Furthermore, in the above embodiment, the bottoms of recesses 16 and 16a are illustrated as angular bottoms, and bottom surface 16B and bottom surface 16aB of these bottoms are described as being composed of the first ceramic crystal particles. However, this is not limited to this. If the bottoms of the recesses are rounded without corners, the portion near the bottoms may be composed of the first ceramic crystal particles.

[0040] In the above embodiment, bottom surface 16B and bottom surface 16aB formed of the first ceramic crystal grains are laser-processed surfaces, but this is not limiting. For example, the surface formed of the first ceramic crystal grains may be formed by laser processing using a laser other than an ultrashort pulse laser, or by any other processing other than laser processing, as long as the first particle size is smaller than the second particle size.

[0041] The electrostatic chuck according to the above embodiment may further include a plurality of heater electrodes formed of a conductive material such as tungsten or molybdenum inside the holding member. In such a configuration, when an object is held by the holding member, the heater electrodes generate heat using power supplied from an external power source, thereby warming the object.

[0042] In the electrostatic chuck according to the above embodiment, a plate-shaped base member may be bonded to the back surface of the holding member. If a coolant flow path is formed inside the base member, when an object is held by the holding member, the coolant flows through the coolant flow path from the base member through the holding member, thereby cooling the object.

[0043] This aspect has been described above based on embodiments and modifications. However, the above-described embodiments are intended to facilitate understanding of this aspect and are not intended to limit this aspect. This aspect may be modified or improved without departing from the spirit and scope of the claims, and equivalents thereof are included in this aspect. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

[0044] The present invention can also be realized in the following forms. [Application example 1] A holding member that is mainly composed of ceramic and holds an object, the holding member has a holding surface that is a surface on which the object is held, At least a portion of the support surface is made up of first ceramic crystal grains, a portion of the holding member located inside the holding surface is made of second ceramic crystal grains; A holding member, wherein a first particle size, which is a particle size of the first ceramic crystal particles, is smaller than a second particle size, which is a particle size of the second ceramic crystal particles. [Application example 2] The holding member according to Application Example 1, The holding surface has a protrusion and a recess, A holding member, wherein the surface is a bottom surface that defines the recess. [Application example 3] The holding member according to Application Example 1 or Application Example 2, A holding member, wherein the surface is a laser-processed surface. [Application example 4] An electrostatic chuck, The holding member according to any one of Application Examples 1 to 3, an electrostatic electrode that generates an electrostatic attractive force on the holding surface. [Explanation of symbols]

[0045] 1, 1a...Electrostatic chuck 10, 10a...holding member 10b…Back side 10f,10fa…holding surface 12...Ring-shaped protrusion 14...Convex part 16, 16a...recess 16B,16aB…Bottom surface 16S, 16aS...Side 22...Through-flow channel 30...Electrostatic electrode

Claims

1. A holding member that is mainly composed of ceramic and holds an object, the holding member has a holding surface that is a surface on which the object is held, At least a portion of the support surface is made of first ceramic crystal grains, a portion of the holding member located inside the holding surface is made of second ceramic crystal grains; a first particle size, which is a particle size of the first ceramic crystal particles, is smaller than a second particle size, which is a particle size of the second ceramic crystal particles; the surface includes the first ceramic crystal grains with exposed interiors; A holding member, wherein the first ceramic crystal grains and the second ceramic crystal grains are made of the same material.

2. The holding member according to claim 1 , The holding surface has a protrusion and a recess, A holding member, wherein the surface is a bottom surface that defines the recess.

3. The holding member according to claim 2, A holding member, wherein the surface is a laser-processed surface.

4. An electrostatic chuck, The holding member according to any one of claims 1 to 3; an electrostatic electrode that generates an electrostatic attractive force on the holding surface.

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