Sample holder

Abstract

A sample holder according to the present disclosure comprises a ceramic body, a base plate, a cylindrical member, and a porous body. The ceramic body has a first surface, a second surface, and a first through-hole. The first surface is a sample holding surface. The second surface is positioned opposite the first surface. The first through-hole passes through the first surface and the second surface. The base plate has a second through-hole and supports the ceramic body. The cylindrical member is positioned inside the second through-hole and has a third through-hole connected to the first through-hole. The porous body is positioned inside the cylindrical member. A first gap is provided between the inner peripheral surface of the cylindrical member and the outer peripheral surface of the porous body.

Description

Sample holder

[0001] The present disclosure relates to a sample holder.

[0002] A sample holder used in a semiconductor manufacturing apparatus or the like is known. The sample holder has, for example, a structure in which a ceramic body on which a sample such as a wafer is placed and a conductive base member that supports the ceramic body are joined via a bonding material.

[0003] In this type of sample holder, through holes penetrating the ceramic body and the base member are formed, and a gas such as helium is supplied to the sample placed on the ceramic body through these through holes.

[0004] In a portion of the above-described through hole that penetrates the base member, a cylindrical member made of ceramic is positioned so as to communicate with the through hole portion of the ceramic body, and a porous body is positioned inside the cylindrical member. With this configuration, the inflow of plasma into the through hole portion of the base member is reduced, so that arcing, which is a discharge in the through hole portion of the base member, and corrosion of the base member due to arcing can be reduced.

[0005] Japanese Patent Laid-Open No. 2020-109806

[0006] The sample holder according to one aspect of the present disclosure includes a ceramic body, a base plate, a cylindrical member, and a porous body. The ceramic body has a first surface, a second surface, and a first through hole. The first surface is a sample holding surface. The second surface is located opposite to the first surface. The first through hole penetrates the first surface and the second surface. The base plate has a second through hole and supports the ceramic body. The cylindrical member is located inside the second through hole and has a third through hole connected to the first through hole. The porous body is located inside the cylindrical member. A first gap is provided between the inner peripheral surface of the cylindrical member and the outer peripheral surface of the porous body.

[0007] Figure 1 is a cross-sectional view showing an example of the configuration of a sample holder according to the first embodiment. Figure 2 is an enlarged cross-sectional view of region R1 shown in Figure 1. Figure 3 is a cross-sectional view taken along line III-III in Figure 2. Figure 4A is a perspective view showing an example of the configuration of a bonding material according to the first embodiment. Figure 4B is a perspective view showing another example of the configuration of a bonding material according to the first embodiment. Figure 5 is a perspective view showing an example of the configuration of a porous body according to the first embodiment. Figure 6A is a cross-sectional view showing an example of the configuration of a sample holder according to the second embodiment. Figure 6B is a cross-sectional view showing another example of the configuration of a sample holder according to the second embodiment. Figure 7A is a cross-sectional view showing an example of the configuration of a sample holder according to the third embodiment. Figure 7B is a cross-sectional view showing another example of the configuration of a sample holder according to the third embodiment. Figure 8A is a cross-sectional view showing an example of the configuration of a sample holder according to the fourth embodiment. Figure 8B is an enlarged cross-sectional view of region R2 shown in Figure 8A. Figure 9A is a cross-sectional view showing an example of the configuration of a sample holder according to the fifth embodiment. Figure 9B is a cross-sectional view taken along line IX-IX in Figure 9A. Figure 10A is a cross-sectional view showing an example of the configuration of a sample holder according to the sixth embodiment. Figure 10B is a cross-sectional view taken along the line X-X in Figure 10A. Figure 11 is a cross-sectional view showing an example of the configuration of the sample holder according to the seventh embodiment. Figure 12A is a cross-sectional view showing an example of the configuration of the sample holder according to the eighth embodiment. Figure 12B is a cross-sectional view showing another example of the configuration of the sample holder according to the eighth embodiment.

[0008] The embodiments for implementing the sample holder according to this disclosure (hereinafter referred to as "Embodiments") will be described in detail below with reference to the drawings. However, this disclosure is not limited by these embodiments. Furthermore, each embodiment can be combined as appropriate, provided that the processing content is not inconsistent. Also, the same parts are denoted by the same reference numerals in each of the following embodiments, and redundant descriptions are omitted.

[0009] Furthermore, in the embodiments described below, expressions such as "constant," "orthogonal," "perpendicular," or "parallel" may be used, but these expressions do not require strict adherence to "constant," "orthogonal," "perpendicular," or "parallel" conditions. In other words, each of the above expressions allows for deviations such as manufacturing accuracy or installation accuracy.

[0010] Furthermore, in the drawings referenced below, for the sake of clarity, mutually orthogonal X, Y, and Z axis directions are sometimes defined, and a Cartesian coordinate system is shown with the positive Z axis pointing vertically upward.

[0011] (First Embodiment) First, the configuration of the sample holder 1 according to the first embodiment will be described with reference to Figures 1 to 3. Figure 1 is a cross-sectional view showing an example of the configuration of the sample holder 1 according to the first embodiment. Figure 2 is an enlarged cross-sectional view of the region R1 shown in Figure 1. Figure 3 is a cross-sectional view taken along line III-III in Figure 2. In Figure 3, the joining material 70, which can be seen in the negative Z-axis direction, is omitted from the description in order to show the presence of the first gap 60.

[0012] As shown in Figure 1, the sample holder 1 comprises a ceramic body 10, a base plate 20, a cylindrical member 30, a porous body 40, and a bonding layer 50. The sample holder 1 is constructed by bonding a disc-shaped base plate 20 made of metal to the lower side of a disc-shaped ceramic body 10.

[0013] The sample holder 1 has multiple gas holes arranged in a plan view, penetrating from the first surface 10a of the ceramic body 10, which is the top surface of the sample holder 1, to the seventh surface 20b of the base plate 20, which is the bottom surface of the sample holder 1. Through these gas holes, a plasma generation gas such as helium is supplied from the bottom of the sample holder 1 to the space on the first surface 10a, which is the sample holding surface. Specifically, the gas flows in the order of the third through-hole 31, the porous body 40, and the first through-hole 11.

[0014] The ceramic body 10 is made of ceramic. The ceramic body 10 may be formed from a ceramic-containing raw material into a flat plate shape, for example, a disc shape. The ceramic body 10 may be made of, for example, aluminum oxide (Al ２ O ３ (Hereafter, it may be referred to as alumina.) Aluminum nitride (AlN), or yttria (Y ２ O ３ ) may also contain as a main component.

[0015] The ceramic body 10 has a first surface 10a which is a sample holding surface, and a second surface 10b located opposite the first surface 10a. The second surface 10b is the surface that is joined to the base plate 20 via a bonding layer 50, which will be described later.

[0016] The ceramic body 10 has a first through-hole 11 that penetrates the first surface 10a and the second surface 10b. This first through-hole 11 constitutes a part of the gas hole in the sample holder 1.

[0017] In this embodiment, the sample holder 1 is an electrostatic chuck that holds the sample by electrostatic force, and as shown in Figure 1, it is equipped with an electrode 12 for electrostatic adsorption inside the ceramic body 10, which is an insulator. The electrode 12 is a thin, flat conductive layer. The electrode 12 is positioned, for example, parallel to the first surface 10a of the ceramic body 10.

[0018] The electrode 12 may be made of a conductor mainly composed of a metal such as molybdenum (Mo), platinum (Pt), or tungsten (W). When a voltage is applied to the electrode 12 from the outside, an electrostatic force is generated between the first surface 10a and the sample, thereby adsorbing and holding the sample.

[0019] Although this example shows two electrodes 12, the number of electrodes 12 is not limited to this. For example, only one electrode 12 may be provided.

[0020] The base plate 20 is a disc-shaped member that supports the ceramic body 10. The base plate 20 is bonded to the second surface 10b of the ceramic body 10 via a bonding layer 50. The base plate 20 is made of a metal such as aluminum.

[0021] The base plate 20 has a sixth surface 20a that is joined to the ceramic body 10 via a bonding layer 50, which will be described later, and a seventh surface 20b located opposite the sixth surface 20a.

[0022] The base plate 20 has a second through-hole 21 that penetrates the sixth surface 20a and the seventh surface 20b. The second through-hole 21 constitutes part of the aforementioned gas hole in the sample holder 1.

[0023] The cylindrical member 30 is a cylindrical member made of an insulating material and is located inside the second through-hole 21. Specifically, the cylindrical member 30 is positioned to cover the inner circumferential surface of the second through-hole 21. As a result, the inner circumferential surface of the second through-hole 21, which is a metal surface, is less likely to be exposed to the plasma entering the gas hole.

[0024] A ceramic material can be used as the insulating material for the cylindrical member 30. For example, alumina or aluminum nitride can be used as the ceramic material.

[0025] The cylindrical member 30 has a third through-hole 31 connected to the first through-hole 11. As shown in Figure 2, the third through-hole 31 may have a first portion 311 and a second portion 312 connected to the first portion 311 and having a smaller diameter than the first portion 311. The first portion 311 is located closer to the first through-hole 11 (ceramic body 10) than the second portion 312. The cylindrical member 30 also has a connecting surface 33 that connects the circumferential surface 311a of the first portion 311 and the circumferential surface 312a of the second portion 312, and a fifth surface 36 that faces the ceramic body 10.

[0026] The porous body 40 is located inside the cylindrical member 30. Specifically, the porous body 40 may be located at the first portion 311 of the cylindrical member 30. In other words, the porous body 40 may be located near the joint between the ceramic body 10 and the base plate 20 in the gas pores.

[0027] The porous body 40 has a porosity sufficient to allow gas to pass through. The porous body 40 serves as a gas channel and is a component that can reduce the flow of plasma used on the first surface 10a, which is the sample holding surface, from entering through the first through-hole 11 and flowing downward (in this case, in the negative Z-axis direction). As the material constituting the porous body 40, a ceramic material such as alumina can be used.

[0028] As shown in Figure 2, the porous body 40 has a third surface 42 facing the ceramic body 10 and a fourth surface 43 located opposite the third surface 42. The fourth surface 43 is the surface facing the connecting surface 33 of the cylindrical member 30.

[0029] The bonding layer 50 is a layer located between the ceramic body 10 and the base plate 20, and it joins the two together. The bonding layer 50 is formed by curing an adhesive made of an insulating material. For example, a silicone-based adhesive can be used as such an adhesive.

[0030] In the sample holder 1 configured as described above, even if plasma enters through the first through-hole 11, the porous body 40 reduces the penetration in the negative Z-axis direction.

[0031] However, because the porous body 40 has low thermal conductivity, when the surface of the porous body 40 is heated by plasma, there is a risk that only the upper surface of the porous body 40 will expand due to heat. In this case, if the porous body 40 and the cylindrical member 30 are in direct or indirect contact without any gaps, the thermal expansion of only the upper part of the cylindrical member 30 may cause distortion in the base plate 20 and the ceramic body 10, resulting in variations in heat dissipation from the ceramic body 10 and a decrease in heat uniformity.

[0032] Furthermore, because the direction of plasma penetration is irregular, the surface of the porous body 40 is easily heated locally, and in that case, the porous body 40 and the upper part of the cylindrical member 30 are prone to uneven thermal expansion. As a result, the base plate 20 and the ceramic body 10 are more prone to distortion, and the uniformity of heating is easily reduced.

[0033] Therefore, the sample holder 1 according to the first embodiment has a first gap 60 between the inner circumferential surface 32 of the cylindrical member 30 and the outer circumferential surface 41 of the porous body 40. With this configuration, even if the porous body 40 is heated by plasma and expands due to thermal expansion, the cylindrical member 30 is less likely to deform due to the presence of the first gap 60, and the base plate 20 and ceramic body 10 are less likely to be distorted. Thus, the sample holder 1 according to the first embodiment has excellent heat uniformity. When the cylindrical member 30 has a first portion 311 and a second portion 312, the inner circumferential surface 32 includes the circumferential surface 311a and the circumferential surface 312a.

[0034] The first gap 60 is annular in plan view and is located in the first portion 311 of the third through hole 31. Specifically, the first gap 60 is located in the region of the first portion 311 that is close to the ceramic body 10. In other words, the first gap 60 is located on the positive Z-axis side between the inner circumferential surface 32 of the cylindrical member 30 and the outer circumferential surface 41 of the porous body 40.

[0035] The radial dimension of the first gap 60 may increase as it moves from the ceramic body 10 side toward the second portion 312 side. With this configuration, plasma that enters the first gap 60 from the first through hole 11 is less likely to flow toward the second portion 312 side. The radial dimension of the first gap 60 is, for example, 10 μm to 100 μm.

[0036] As shown in Figure 2, a bonding material 70 may be positioned between the cylindrical member 30 and the porous body 40. The bonding material 70 joins the inner circumferential surface 32 of the cylindrical member 30 and the outer circumferential surface 41 of the porous body 40. Alternatively, the bonding material 70 may join the connecting surface 33 of the cylindrical member 30 and the fourth surface 43 of the porous body 40. In other words, the first gap 60 is located in the region where the ceramic body 10 is desired from the bonding material 70, and the bonding material 70 may be located in the region between the cylindrical member 30 and the porous body 40 other than the first gap 60.

[0037] In this way, the position of the bonding material 70 between the cylindrical member 30 and the porous body 40 makes it difficult for the plasma that enters after the first through hole 11 to flow towards the second portion 312.

[0038] Next, the joining material 70 according to the first embodiment will be described further with reference to Figures 4A and 4B. Figure 4A is a perspective view showing an example of the configuration of the joining material 70 according to the first embodiment. Figure 4B is a perspective view showing another example of the configuration of the joining material 70 according to the first embodiment.

[0039] As shown in FIGS. 4A and 4B, the bonding material 70 may have different dimensions in the axial direction (here, the Z-axis direction) of the third through-hole 31 across the outer peripheral surface 41 of the porous body 40 (see FIG. 2). In other words, the depth of the first gap 60 may be different across the outer peripheral surface 41 of the porous body 40. Specifically, as shown in FIG. 4A, the position of the upper end of the bonding material 70 in the Z-axis direction may gradually change along the outer peripheral surface 41 of the porous body 40. Further, as shown in FIG. 4B, the position of the upper end of the bonding material 70 in the Z-axis direction may change so as to meander along the outer peripheral surface 41 of the porous body 40.

[0040] Thus, since the dimensions of the bonding material 70 in the axial direction of the third through-hole 31 are different across the outer peripheral surface 41 of the porous body 40, the boundary between the first gap 60 and the bonding material 70 is different in the axial direction of the third through-hole 31, so that stress is less likely to concentrate. Therefore, the cylindrical member 30 is less likely to deform, and the ceramic body 10 is less likely to be distorted. Accordingly, the sample holder 1 has better heat uniformity.

[0041] Next, the porous body 40 according to the first embodiment will be described with reference to FIG. 5. FIG. 5 is a perspective view showing an example of the configuration of the porous body 40 according to the first embodiment. As shown in FIG. 5, the porous body 40 may have a three-dimensional network structure. Specifically, the porous body 40 may have a plurality of holes. The holes may extend while meandering inside the porous body 40.

[0042] According to such a configuration, since the plasma that has entered from the first through-hole 11 is less likely to pass through the porous body 40, the plasma is less likely to flow to the second part 312 side.

[0043] As described above, the sample holder 1 according to the first embodiment has a first gap 60 between the inner peripheral surface 32 of the cylindrical member 30 and the outer peripheral surface 41 of the porous body 40. According to such a configuration, even if the porous body 40 is heated by the plasma and thermally expands, the presence of the first gap 60 makes the cylindrical member 30 less likely to deform, and the base plate 20 and the ceramic body 10 are less likely to be distorted. Accordingly, the sample holder 1 according to the first embodiment has excellent heat uniformity.

[0044] (Second Embodiment) FIG. 6A is a cross-sectional view showing an example of the configuration of the sample holder 1 according to the second embodiment. FIG. 6B is a cross-sectional view showing another example of the configuration of the sample holder 1 according to the second embodiment. As shown in FIGS. 6A and 6B, the porous body 40 may have a first chamfer portion 44 between the fourth surface 43 and the outer peripheral surface 41.

[0045] The bonding material 70 may be located between the first chamfer portion 44 and the portion of the cylindrical member 30 that faces the first chamfer portion 44. Specifically, as shown in FIG. 6B, the bonding material 70 may be located only between the first chamfer portion 44 and the corner portion 34 formed by the circumferential surface 311a of the first part 311 and the connection surface 33 of the cylindrical member 30, which is the portion of the cylindrical member 30 that faces the first chamfer portion 44, in other words. Further, as shown in FIG. 6A, the bonding material 70 may be located not only between the first chamfer portion 44 and the corner portion 34, but also between the circumferential surface 311a of the first part 311 and the outer peripheral surface 41 of the porous body 40, and between the connection surface 33 of the cylindrical member 30 and the fourth surface 43 of the porous body 40.

[0046] Thus, since the porous body 40 has the first chamfer portion 44, when stress is applied to the cylindrical member 30, the first chamfer portion 44 faces the corner portion 34, so that the stress is easily dispersed. Further, since the bonding material 70 is located between the corner portion 34 and the first chamfer portion 44, the stress is more easily dispersed.

[0047] (Third Embodiment) FIG. 7A is a cross-sectional view showing an example of the configuration of the sample holder 1 according to the third embodiment. FIG. 7B is a cross-sectional view showing another example of the configuration of the sample holder 1 according to the third embodiment. As shown in FIGS. 7A and 7B, a second gap 80 may be located between the porous body 40 and the connection surface 33. Specifically, the second gap 80 may be located between the fourth surface 43 of the porous body 40 and the connection surface 33. The second gap 80 may be located in a region close to the second part 312 between the fourth surface 43 and the connection surface 33. In other words, the second gap 80 may be located in a region where the bonding material 70 is located between the fourth surface 43 and the connection surface 33, that is, a region other than the region between the first chamfer portion 44 and the corner portion 34.

[0048] With this configuration, when gas is introduced from the negative Z-axis side of the third through-hole 31, the gas spreads out into the second gap 80 before entering the porous body 40, so the gas spreads easily in the radial direction of the porous body 40. As a result, the gas that passes through the porous body 40 flows uniformly in the radial direction. In addition, since the temperature decreases in the area where the gas flows, the possibility of a localized temperature drop within the porous body 40 can be reduced.

[0049] (Fourth Embodiment) Figure 8A is a cross-sectional view showing an example of the configuration of the sample holder 1 according to the fourth embodiment. Figure 8B is an enlarged cross-sectional view of region R2 shown in Figure 8A. As shown in Figure 8B, the corner portion 34 formed by the circumferential surface 311a and the connecting surface 33 of the first portion 311 may have an R shape. Also, the first chamfered portion 44 may have a C shape.

[0050] With this configuration, when stress is applied to the cylindrical member 30, the stress is more easily distributed at the corner portion 34 and the first chamfered portion 44.

[0051] (Fifth Embodiment) Figure 9A is a cross-sectional view showing an example of the configuration of the sample holder 1 according to the fifth embodiment. Figure 9B is a cross-sectional view taken along the line IX-IX in Figure 9A. For ease of understanding, in Figure 9B, hatching is applied to the region showing the porous body 40 and the region showing the bonding material 70. As shown in Figures 9A and 9B, the bonding material 70 may be positioned across the opposing region between the cylindrical member 30 and the porous body 40 other than the first gap 60, and the circumferential surface 312a of the second portion 312. Specifically, the bonding material 70 may be positioned across the region between the inner circumferential surface 32 of the cylindrical member 30 and the outer circumferential surface 41 of the porous body 40, the region between the fourth surface 43 of the porous body 40 and the connecting surface 33, and the circumferential surface 312a of the second portion 312.

[0052] With this configuration, even if the cylindrical member 30 undergoes repeated thermal expansion and contraction, a gap is less likely to form between the porous body 40 and the cylindrical member 30. Therefore, the gas is more reliably introduced into the porous body 40.

[0053] (Sixth Embodiment) Figure 10A is a cross-sectional view showing an example of the configuration of the sample holder 1 according to the sixth embodiment. Figure 10B is a cross-sectional view taken along line X-X in Figure 10A. For ease of understanding, in Figure 10B, the area showing the porous body 40 is hatched. As shown in Figure 10A, the connecting surface 33 may have a second chamfered portion 45 located between it and the second portion 312.

[0054] The joining material 70 may also be located in the region between the second chamfered portion 45 of the cylindrical member 30 and the fourth surface 43 of the porous body 40.

[0055] With this configuration, the sample holder 1 has excellent adhesion between the porous body 40 and the cylindrical member 30.

[0056] (Seventh Embodiment) Figure 11 is a cross-sectional view showing an example of the configuration of the sample holder 1 according to the seventh embodiment. As shown in Figure 11, the sample holder 1 may have a third gap 90 located between the ceramic body 10 and the porous body 40. Specifically, the third gap 90 may be located between the second surface 10b of the ceramic body 10 and the third surface 42 of the porous body 40.

[0057] With this configuration, even if the porous body 40 undergoes thermal expansion, the presence of the third gap 90 makes it difficult for the ceramic body 10 to deform. Furthermore, the presence of the third gap 90 makes it difficult for heat to be transferred from the porous body 40 to the ceramic body 10.

[0058] (Eighth Embodiment) Figure 12A is a cross-sectional view showing an example of the configuration of the sample holder 1 according to the eighth embodiment. Figure 12B is a cross-sectional view showing another example of the configuration of the sample holder 1 according to the eighth embodiment. As shown in Figures 12A and 12B, a fourth gap 100 may be located between the ceramic body 10 and the cylindrical member 30. Specifically, as shown in Figure 12A, the fourth gap 100 may be located between the second surface 10b of the ceramic body 10 and the fifth surface 36 of the cylindrical member 30. Also, as shown in Figure 12B, the ceramic body 10 may have a recess 13 on the second surface 10b. The recess 13 is located on the second surface 10b facing the cylindrical member 30 and the porous body 40. The fourth gap 100 may be located in the recess 13.

[0059] In this way, having the fourth gap 100 makes it difficult for the ceramic body 10 to deform even when the cylindrical member 30 undergoes thermal expansion. Furthermore, having the fourth gap 100 makes it difficult for heat to be transferred from the cylindrical member 30 to the ceramic body 10.

[0060] Furthermore, this technology can also take the following configurations: (1) A sample holder comprising: a ceramic body having a first surface which is a sample holding surface, a second surface located opposite the first surface, and a first through-hole that penetrates the first surface and the second surface; a base plate having a second through-hole and supporting the ceramic body; a cylindrical member located inside the second through-hole and having a third through-hole connected to the first through-hole; and a porous body located inside the cylindrical member, wherein there is a first gap between the inner circumferential surface of the cylindrical member and the outer circumferential surface of the porous body. (2) The sample holder according to (1), wherein the third through-hole has a first portion and a second portion connected to the first portion and having a smaller diameter than the first portion; the porous body is located in the first portion and has a joining material in the first portion that joins the inner circumferential surface of the cylindrical member and the outer circumferential surface of the porous body; the dimensions of the joining material in the axial direction of the third through-hole differ across the outer circumferential surface of the porous body. (3) The sample holder according to (1) or (2), wherein the porous body has a third surface facing the ceramic body, a fourth surface located opposite the third surface, and a first chamfered portion located between the fourth surface and the outer peripheral surface. (4) The sample holder according to any one of (1) to (3), wherein the third through hole has a first portion and a second portion connected to the first portion and having a smaller diameter than the first portion, the porous body is located in the first portion, the cylindrical member has a connecting surface that connects the circumferential surface of the first portion and the circumferential surface of the second portion, and a second gap is located between the porous body and the connecting surface. (5) The sample holder according to (3), wherein the third through hole has a first portion and a second portion connected to the first portion and having a smaller diameter than the first portion, the porous body is located in the first portion, the cylindrical member has a connecting surface that connects the circumferential surface of the first portion and the circumferential surface of the second portion, the corner formed by the circumferential surface of the first portion and the connecting surface has an R shape, and the first chamfered portion has a C shape.(6) The sample holder according to any one of (1) to (3), wherein the third through hole has a first portion and a second portion connected to the first portion and having a smaller diameter than the first portion, the porous body is located in the first portion and has a joining material in the first portion that joins the inner circumferential surface of the cylindrical member and the outer circumferential surface of the porous body, the cylindrical member has a connecting surface that connects the circumferential surface of the first portion and the circumferential surface of the second portion, the first gap is located in a region that is adjacent to the ceramic body from the joining material, and the joining material is located across the region between the cylindrical member and the porous body other than the first gap and the circumferential surface of the second portion. (7) The sample holder according to any one of (1) to (3), wherein the third through-hole has a first portion and a second portion connected to the first portion and having a smaller diameter than the first portion, the porous body is located in the first portion and has a joining material in the first portion that joins the inner circumferential surface of the cylindrical member and the outer circumferential surface of the porous body, the cylindrical member has a connecting surface that connects the circumferential surface of the first portion and the circumferential surface of the second portion, the connecting surface has a second chamfered portion located between it and the second portion, and the joining material is also located in the region between the second chamfered portion of the cylindrical member and the opposing surface of the connecting surface in the porous body. (8) The sample holder according to any one of (1) to (7), wherein the porous body has a third surface facing the ceramic body, and a third gap is located between the ceramic body and the third surface. (9) The sample holder according to (8), wherein the cylindrical member has a fifth surface facing the ceramic body, and a fourth gap is located between the ceramic body and the fifth surface. (10) The sample holder according to any one of (1) to (9), wherein the porous body has a three-dimensional network structure.

[0061] The embodiments disclosed herein should be considered in all respects as illustrative and not restrictive. Indeed, the embodiments described above can be embodied in a variety of forms. For example, while a configuration using Coulomb force as the electrostatic chuck has been illustrated, a configuration using Johnson-Rabec force is also applicable. Furthermore, the embodiments described above may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims.

[0062] 1 Sample holder 10 Ceramic body 10a First surface 10b Second surface 11 First through hole 20 Base plate 20a Sixth surface 20b Seventh surface 21 Second through hole 30 Cylindrical member 31 Third through hole 32 Inner circumferential surface 33 Connecting surface 34 Corner 36 Fifth surface 40 Porous body 41 Outer circumferential surface 42 Third surface 43 Fourth surface 44 First chamfered part 45 Second chamfered part 60 First gap 70 Joining material 80 Second gap 90 Third gap 100 Fourth gap 311 First part 312 Second part

Claims

1. A sample holder comprising: a ceramic body having a first surface which is a sample holding surface, a second surface located opposite the first surface, and a first through-hole that penetrates the first surface and the second surface; a base plate having a second through-hole and supporting the ceramic body; a cylindrical member located inside the second through-hole and having a third through-hole connected to the first through-hole; and a porous body located inside the cylindrical member, wherein there is a first gap between the inner circumferential surface of the cylindrical member and the outer circumferential surface of the porous body.

2. The sample holder according to claim 1, wherein the third through-hole has a first portion and a second portion connected to the first portion and having a smaller diameter than the first portion, the porous body is located in the first portion and has a joining material in the first portion that joins the inner circumferential surface of the cylindrical member and the outer circumferential surface of the porous body, and the dimensions of the joining material in the axial direction of the third through-hole differ across the outer circumferential surface of the porous body.

3. The sample holder according to claim 1 or 2, wherein the porous body has a third surface facing the ceramic body, a fourth surface located opposite the third surface, and a first chamfered portion located between the fourth surface and the outer peripheral surface.

4. The sample holder according to any one of claims 1 to 3, wherein the third through-hole has a first portion and a second portion connected to the first portion and having a smaller diameter than the first portion, the porous body is located in the first portion, the cylindrical member has a connecting surface that connects the circumferential surface of the first portion and the circumferential surface of the second portion, and a second gap is located between the porous body and the connecting surface.

5. The sample holder according to claim 3, wherein the third through-hole has a first portion and a second portion connected to the first portion and having a smaller diameter than the first portion, the porous body is located in the first portion, the cylindrical member has a connecting surface that connects the circumferential surface of the first portion and the circumferential surface of the second portion, the corner formed by the circumferential surface of the first portion and the connecting surface has an R shape, and the first chamfered portion has a C shape.

6. The sample holder according to any one of claims 1 to 3, wherein the third through-hole has a first portion and a second portion connected to the first portion and having a smaller diameter than the first portion, the porous body is located in the first portion and has a joining material in the first portion that joins the inner circumferential surface of the cylindrical member and the outer circumferential surface of the porous body, the cylindrical member has a connecting surface that connects the circumferential surface of the first portion and the circumferential surface of the second portion, the first gap is located in a region that is adjacent to the ceramic body from the joining material, and the joining material is located across the region between the cylindrical member and the porous body other than the first gap and the circumferential surface of the second portion.

7. The sample holder according to any one of claims 1 to 3, wherein the third through-hole has a first portion and a second portion connected to the first portion and having a smaller diameter than the first portion, the porous body is located in the first portion and has a joining material in the first portion that joins the inner circumferential surface of the cylindrical member and the outer circumferential surface of the porous body, the cylindrical member has a connecting surface that connects the circumferential surface of the first portion and the circumferential surface of the second portion, the connecting surface has a second chamfered portion located between it and the second portion, and the joining material is also located in the region between the second chamfered portion of the cylindrical member and the opposing surface of the connecting surface in the porous body.

8. The sample holder according to any one of claims 1 to 7, wherein the porous body has a third surface facing the ceramic body, and a third gap is located between the ceramic body and the third surface.

9. The sample holder according to claim 8, wherein the cylindrical member has a fifth surface facing the ceramic body, and a fourth gap is located between the ceramic body and the fifth surface.

10. The sample holder according to any one of claims 1 to 9, wherein the porous body has a three-dimensional network structure.

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