Sample holder
The sample holder design addresses heat uniformity issues by using an intermediate member with a convex protrusion and buffer member to maintain contact and reduce deformation, achieving consistent temperature distribution across the sample surface.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- KYOCERA CORP
- Filing Date
- 2025-12-02
- Publication Date
- 2026-06-25
AI Technical Summary
Existing sample holders experience deformation and non-uniform heat distribution at high temperatures due to temperature differences between the ceramic body and the base plate, leading to gaps and reduced heat uniformity on the sample holding surface.
A sample holder design incorporating a ceramic body, a base plate, an intermediate member with a lower thermal expansion and conductivity than the ceramic body, and a fixing member, featuring a convex protrusion on the intermediate member to maintain contact with the ceramic body, along with a buffer member to relieve stress and ensure even heat distribution.
The design achieves excellent heat uniformity by minimizing deformation and maintaining consistent temperature across the sample holding surface even at high temperatures, preventing gaps and ensuring stable heat conduction.
Smart Images
Figure JP2025042022_25062026_PF_FP_ABST
Abstract
Description
Sample holder
[0001] The present disclosure relates to a sample holder.
[0002] A sample holder for holding a sample such as a semiconductor wafer to be plasma-treated is known. The sample holder has a ceramic body incorporating an electrode, and the sample is placed on the surface of this ceramic body. Further, the sample holder is configured by joining a metal base plate to the back surface of the ceramic body in order to enhance the isothermal property on the surface of the ceramic body.
[0003] Patent Document 1 discloses a structure in which an anti-deformation plate made of a copper plate that plays a role of preventing excessive deformation of the ceramic body is interposed between the ceramic body and the base plate, and these are fixed by screwing.
[0004] Japanese Unexamined Patent Application Publication No. 2011-159678
[0005] The sample holder according to one aspect of the present disclosure includes a ceramic body, a base plate, an intermediate member, and a fixing member. The ceramic body has a first surface that is a sample holding surface and a second surface located opposite to the first surface, and has an electrode inside. The base plate supports the ceramic body. The intermediate member is located between the ceramic body and the base plate. The fixing member fixes the ceramic body and the base plate. The intermediate member has a lower coefficient of thermal expansion and lower thermal conductivity than the ceramic body, and has a third surface facing the second surface. The third surface includes a convex portion that abuts against the second surface of the ceramic body at the outer peripheral portion.
[0006] Figure 1 is a schematic cross-sectional view showing a sample holder according to the first embodiment. Figure 2 is a schematic cross-sectional view showing an intermediate member according to the first embodiment. Figure 3 is a schematic plan view showing an intermediate member according to the first embodiment. Figure 4 is a schematic cross-sectional view showing an intermediate member according to the second embodiment. Figure 5 is a schematic enlarged cross-sectional view showing a protrusion according to the second embodiment. Figure 6 is a schematic cross-sectional view showing an intermediate member according to the third embodiment. Figure 7 is a schematic plan view showing an intermediate member according to the third embodiment. Figure 8 is a schematic cross-sectional view showing an intermediate member according to the fourth embodiment. Figure 9 is a schematic enlarged cross-sectional view showing a column portion according to the fourth embodiment. Figure 10 is a schematic plan view showing an intermediate member according to the fourth embodiment. Figure 11 is a schematic plan view showing another example of an intermediate member according to the fourth embodiment. Figure 12 is a schematic cross-sectional view showing a sample holder according to the fifth embodiment.
[0007] 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.
[0008] Furthermore, in the embodiments described below, expressions such as "constant," "vertical," or "parallel" may be used, but these expressions do not require strict "constant," "vertical," or "parallel" conditions. In other words, each of the above expressions allows for deviations such as manufacturing accuracy or installation accuracy.
[0009] The technology described in Patent Document 1 has room for further improvement in terms of improving heat uniformity.
[0010] Specifically, if the structure described in Patent Document 1 is used at a high temperature of, for example, 300°C or higher, the deformation prevention plate may bend due to the temperature difference between the high-temperature ceramic body and the base plate. When the deformation prevention plate bends, a partial gap may form between the ceramic body and the deformation prevention plate, which may reduce the uniformity of heat on the surface of the ceramic body, i.e., the sample holding surface.
[0011] This disclosure has been made in view of the above, and aims to provide a sample holder that exhibits excellent heat uniformity even when used at high temperatures.
[0012] (First Embodiment) First, the configuration of the sample holder 100 according to the first embodiment will be described with reference to Figure 1. Figure 1 is a schematic cross-sectional view showing the sample holder 100 according to the first embodiment.
[0013] As shown in Figure 1, the sample holder 100 comprises a ceramic body 10, a base plate 20, an intermediate member 30, and a fixing member 50. The dimensions of these components are not limited to the illustrated example and may be similar to those of conventionally known sample holders.
[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 ), aluminum nitride (AlN), or yttrium oxide (Y ２ O ３ ) may also contain as a main component.
[0015] The ceramic body 10 has, for example, a first surface 10a and a second surface 10b. The first surface 10a is a sample holding surface that supports the workpiece W, such as a semiconductor wafer. The second surface 10b is located on the opposite side from the first surface 10a. The ceramic body 10 may have a plurality of cylindrical protrusions on the first surface 10a.
[0016] The ceramic body 10 has an electrode 11 inside. The electrode 11 is connected to an external power source (not shown). The sample holder 100 attracts and holds the object to be processed W on the first surface 10a by electrostatic force generated when a DC voltage is applied to the electrode 11 from the power source. As the material of the electrode 11, metals such as platinum (Pt), tungsten (W), and molybdenum (Mo) can be used. However, the material of the electrode 11 is not limited to these. Inside the ceramic body 10, an electrode for a heater (not shown) may be located to adjust the temperature of the sample.
[0017] Although Figure 1 shows a cross-sectional view in which two electrodes 11 are visible, the configuration of the electrodes 11 is not limited to this.
[0018] The base plate 20 is a disc-shaped member that supports the ceramic body 10. The base plate 20 is located on the second surface 10b side of the ceramic body 10 via an intermediate member 30. The base plate 20 is formed from a metallic material such as aluminum or titanium, or a metal-ceramic composite material (MMC (Metal Matrix Composites)) such as AlSiC.
[0019] The base plate 20 has a fifth surface 20a that faces the second surface 10b of the ceramic body 10 via an intermediate member 30, a sixth surface 20b located opposite the fifth surface 20a, and a through hole 21 located inside the outer peripheral edge of the ceramic body 10 and penetrating the fifth surface 20a and the sixth surface 20b.
[0020] The intermediate member 30 is located between the ceramic body 10 and the base plate 20. The intermediate member 30 has a lower coefficient of thermal expansion and thermal conductivity than the ceramic body 10. Because the coefficient of thermal expansion of the intermediate member 30 is lower than that of the ceramic body 10, deformation due to temperature differences in the thickness direction of the intermediate member 30 can be reduced even when heated to, for example, 300°C or higher. Such an intermediate member 30 may be, for example, a dense material such as cordierite or quartz, or a porous ceramic material. The intermediate member 30 only needs to have a lower coefficient of thermal expansion and thermal conductivity than the ceramic body 10, and may be made of the same material as the ceramic body 10. Here, the coefficient of thermal expansion can be measured by the laser flash method or the temperature gradient method, and the thermal conductivity can be measured by the TMA (ThermoMechanical Analyzer) method.
[0021] The intermediate member 30 has a third surface 30a facing the second surface 10b of the ceramic body 10, a fourth surface 30b located opposite the third surface 30a, and a through hole 31 that penetrates the third surface 30a and the fourth surface 30b. The through hole 31 communicates with the through hole 41 of the buffer member 40, which will be described later.
[0022] The sample holder 100 may have a buffer member 40. The buffer member 40 is located between the intermediate member 30 and the base plate 20. The buffer member 40 is made of a cured insulating material. For example, silicone can be used as such an insulating material.
[0023] The position of the buffer member 40 between the intermediate member 30 and the base plate 20 allows the buffer member 40 to relieve stress even when the intermediate member 30 undergoes thermal expansion. As a result, the pressing force on the ceramic body 10 due to the thermal expansion of the intermediate member 30 is reduced, and the deformation of the ceramic body 10 is minimized, resulting in excellent heat uniformity for the sample holder 100.
[0024] The buffer member 40 has through holes 41 that penetrate both main surfaces. The through holes 41 communicate with the through holes 21 of the base plate 20 and the through holes 31 of the intermediate member 30.
[0025] The fixing member 50 fixes the ceramic body 10 and the base plate 20. The fixing member 50 is positioned corresponding to the through hole 21 in the base plate 20. The fixing member 50 has a column portion 51 and a fixing portion 52.
[0026] The column portion 51 has its first end in the extending direction joined to the second surface 10b of the ceramic body 10 by a joining material (not shown), and penetrates through the through hole 21 of the base plate 20, the through hole 31 of the intermediate member 30, and the through hole 41 of the buffer member 40. The column portion 51 is made of metal such as iron or stainless steel, and more specifically, it is preferably made of a material with a similar coefficient of thermal expansion to the ceramic body 10, such as an Fe-Ni-Co alloy. A screw groove (not shown) is formed on at least the side surface of the second end in the extending direction of the column portion 51. The column portion 51 is, for example, a bolt.
[0027] The fixing part 52 is located on the second end side of the column part 51. The fixing part 52 is made of metal, such as iron or stainless steel. The fixing part 52 presses the base plate 20 toward the second surface 10b of the ceramic body 10, thereby fixing the base plate 20 to the ceramic body 10. For example, the fixing part 52 is a nut having a screw hole with a screw groove formed on its inner surface that corresponds to the screw groove at the second end of the column part 51. The fixing part 52 is rotatably attached to the second end of the column part 51 with its screw hole. By rotating, the fixing part 52 moves toward the ceramic body 10 along the axis of the column part 51, generating a pressing force that presses the base plate 20 against the second surface 10b of the ceramic body 10. This pressing force allows the fixing part 52 to fix the base plate 20 to the ceramic body 10.
[0028] The fixing member 50 may have an elastic body 53 and a retaining plate 54. The elastic body 53 is located between the fixing part 52 and the base plate 20. The elastic body 53 may be an elastic annular body. The elastic body 53 may be, for example, an O-ring. The retaining plate 54 is located between the fixing part 52 and the elastic body 53. The retaining plate 54 is a disc-shaped member with a hole formed in the center through which the column part 51 can be inserted. The retaining plate 54 may be made of metal, such as iron or stainless steel.
[0029] Although Figure 1 shows an example where two fixing members 50 are visible in the cross-sectional view, the number of fixing members 50 is not limited to this.
[0030] If the sample holder 100 configured as described above is used at a high temperature of, for example, 300°C or higher, the third surface 30a of the intermediate member 30 may bend convexly due to the temperature difference between the high-temperature ceramic body 10 and the base plate 20. Specifically, this bending refers to a convex curvature such that the center of the third surface 30a of the intermediate member 30 is closer to the ceramic body 10. If the entire third surface 30a of the intermediate member 30 is a flat surface, then if the third surface 30a of the intermediate member 30 is bent convexly, a gap may be created between the outer periphery of the second surface 10b of the ceramic body 10 and the outer periphery of the third surface 30a of the intermediate member 30, which may reduce the uniformity of heat distribution on the first surface 10a of the ceramic body 10.
[0031] Therefore, the intermediate member 30 of the sample holder 100 according to the first embodiment is provided with a protrusion 32 on the outer circumference of the third surface 30a that abuts against the ceramic body 10. Specifically, the protrusion 32 abuts against the outer circumference of the second surface 10b of the ceramic body 10.
[0032] With this configuration, there is a space between the inner circumference of the second surface 10b of the ceramic body 10 and the inner circumference of the third surface 30a of the intermediate member 30. Therefore, even when the sample holder 100 is used at high temperatures, the third surface 30a of the intermediate member 30 curves to fill this space, making it difficult for a gap to form between the outer circumference of the second surface 10b of the ceramic body 10 and the outer circumference of the third surface 30a of the intermediate member 30. Consequently, the sample holder 100 according to the first embodiment has excellent heat uniformity.
[0033] Here, the outer periphery of the intermediate member 30 may be a circumferential region including the protrusion 32. The outer periphery of the intermediate member 30 may be a region of 10 mm or less from the outer edge of the intermediate member 30. The inner periphery of the intermediate member 30 may be a region located more centrally than the outer periphery of the intermediate member 30.
[0034] Next, the configuration of the intermediate member 30 according to the first embodiment will be described with reference to Figures 2 and 3. Figure 2 is a schematic cross-sectional view showing the intermediate member 30 according to the first embodiment. Figure 3 is a schematic plan view showing the intermediate member 30 according to the first embodiment. In Figure 3, the protrusions 32 that come into contact with the ceramic body 10 are indicated by dots.
[0035] The intermediate member 30 may be a disc-shaped material with the same diameter as the ceramic body 10. As shown in Figure 2, the intermediate member 30 may have a constant diameter from the third surface 30a to the fourth surface 30b.
[0036] As shown in Figure 2, the inner circumference of the third surface 30a of the intermediate member 30 may be a concave curved surface. Here, a concave curved surface is a surface with few irregular parts that cause localized high temperatures. With this configuration, the surface temperature of the third surface 30a facing the ceramic body 10 is less likely to fluctuate compared to the case where there are irregular parts in the inner circumference. Therefore, the sample holder 100 has excellent heat uniformity.
[0037] As shown in Figure 2, the concave surface is positioned such that the thickness of the intermediate member 30 increases from the center toward the outer periphery. The maximum depth of the concave surface, i.e., the distance from the tip of the convex portion 32 of the third surface 30a in the thickness direction of the intermediate member 30 to the most recessed position of the concave surface, may be, for example, 5 to 100 μm. The most recessed position of the concave surface may be located at the center of the third surface 30a. The radius of curvature of the concave surface at the center of the third surface 30a may be greater than the radius of curvature of the concave surface at a position closer to the outer periphery than the center of the third surface 30a.
[0038] As shown in Figure 3, the protrusion 32 of the intermediate member 30 may be annular in plan view. In other words, the contact portion between the second surface 10b of the ceramic body 10 and the third surface 30a of the intermediate member 30 may be annular in plan view. With this configuration, heat is propagated evenly along the outer circumference of the intermediate member 30, so that the heat conduction in the thickness direction of the intermediate member 30 is stable, and the uniform heating of the sample holder 100 is excellent.
[0039] The convex portion 32 may be located in a region including the outer peripheral edge of the intermediate member 30. The convex portion 32 may be located in a region 1 to 10 mm or less from the outer peripheral edge of the intermediate member 30.
[0040] The intermediate member 30 may be formed of a single member. In other words, it may be composed of a single member. According to such a configuration, compared with the case where the intermediate member 30 is formed of a plurality of members, it is less likely to form a portion where the temperature changes locally, and heat is likely to propagate evenly.
[0041] As described above, the intermediate member 30 of the sample holder 100 according to the first embodiment includes a convex portion 32 that abuts on the ceramic body 10 at the outer peripheral portion of the third surface 30a. Thereby, even when the sample holder 100 is used at a high temperature, a gap is unlikely to occur between the outer peripheral portion of the second surface 10b of the ceramic body 10 and the outer peripheral portion of the third surface 30a of the intermediate member 30. Therefore, the sample holder 100 according to the first embodiment has excellent heat uniformity.
[0042] In FIG. 1, an example of fixing the ceramic body 10 and the base plate 20 using the fixing member 50 having the column portion 51 and the fixing portion 52 is shown, but the fixing method of the ceramic body 10 and the base plate 20 is not limited to this. For example, the ceramic body 10 and the base plate 20 may be fixed using a fixing member that fixes the ceramic body 10 and the base plate 20 from the outside. Also, the ceramic body 10 and the base plate 20 may be fixed using other mechanical fixing members.
[0043] Also, in FIG. 2, an example where the inner peripheral portion of the third surface 30a of the intermediate member 30 is a concave curved surface is shown, but it is not limited to this. For example, the inner peripheral portion of the third surface 30a may be a flat surface.
[0044] (Second Embodiment) FIG. 4 is a schematic cross-sectional view showing the intermediate member 30 according to the second embodiment. FIG. 5 is a schematic enlarged cross-sectional view showing the convex portion 32 according to the second embodiment.
[0045] As shown in FIGS. 4 and 5, the third surface 30a of the intermediate member 30 may have a step between the convex portion 32 located on the outer peripheral portion and the inner peripheral portion. Specifically, the inner surface 32b of the convex portion 32 may be a surface perpendicular to the fourth surface 30b.
[0046] The opposing surface 32a of the convex portion 32 with respect to the second surface 10b (see FIG. 1) of the ceramic body 10 may be inclined upward toward the outer peripheral edge of the third surface 30a. In other words, the opposing surface 32a may be inclined in a direction in which the distance from the second surface 10b decreases as it approaches the outer peripheral edge of the third surface 30a.
[0047] According to such a configuration, when the sample holder 100 is heated and the third surface 30a is curved convexly, the opposing surface 32a approaches in a direction parallel to the second surface 10b, so that a gap is unlikely to occur between the outer peripheral portion of the second surface 10b of the ceramic body 10 and the opposing surface 32a of the convex portion 32 of the intermediate member 30. Therefore, the sample holder 100 has excellent heat uniformity.
[0048] Also, the corner portion 33 located at the lower end of the convex portion 32 may have an R shape. Such a corner portion 33 is a portion where the inner surface 32b of the convex portion 32 and the concave curved surface of the inner peripheral portion are in contact.
[0049] Thus, since the corner portion 33 of the convex portion 32 has an R shape, stress concentration at such a corner portion 33 can be reduced, so that the strength in the vicinity of the convex portion 32 in the intermediate member 30 can be improved. In addition, since local high temperature in the vicinity of the corner portion 33 can be reduced, the sample holder 100 has excellent heat uniformity.
[0050] (Third Embodiment) FIG. 6 is a schematic cross-sectional view showing the intermediate member 30 according to the third embodiment. FIG. 7 is a schematic plan view showing the intermediate member 30 according to the third embodiment. In FIG. 7, the convex portion 32 and the column portion 35 are shown by dots.
[0051] The third surface 30a of the intermediate member 30 may have a recess 34 in the inner peripheral portion. As shown in FIG. 7, the recess 34 may be circular in plan view. The recess 34 may be a region surrounded by the inner surface of the convex portion 32. The third surface 30a may have a column portion 35 at the center of the recess 34.
[0052] Thus, because the intermediate member 30 has a recess 34, the temperature in the space between the second surface 10b of the ceramic body 10 and the third surface 30a of the intermediate member 30 stabilizes quickly due to gas convection in that space, allowing the sample holder 100 to be heated uniformly early. Furthermore, if high-temperature and low-temperature regions are formed inside the ceramic body 10, the recess 34 of the intermediate member 30 can be positioned to face the low-temperature region, thereby locally suppressing heat loss from the ceramic body 10, and thus the first surface 10a of the ceramic body 10 has excellent heat uniformity.
[0053] (Fourth Embodiment) Figure 8 is a schematic cross-sectional view showing the intermediate member 30 according to the fourth embodiment. Figure 9 is a schematic enlarged cross-sectional view showing the column portion 35 according to the fourth embodiment. Figure 10 is a schematic plan view showing the intermediate member 30 according to the fourth embodiment. Figure 11 is a schematic plan view showing another example of the intermediate member 30 according to the fourth embodiment. Note that in Figure 10, the convex portion 32 and the column portion 35 are indicated by dots.
[0054] As shown in Figures 8 and 9, the third surface 30a of the intermediate member 30 may have a plurality of columnar portions 35 in the recess 34. The columnar portions 35 extend toward the second surface 10b of the ceramic body 10 (see Figure 1).
[0055] As shown in Figure 10, the multiple columnar portions 35 may be arranged at intervals along the radial direction of the intermediate member 30. Alternatively, the multiple columnar portions 35 may be arranged at intervals along the circumferential direction of the intermediate member 30. That is, the multiple columnar portions 35 may be arranged radially from the center of the third surface 30a of the intermediate member 30. The cross-sectional shape of the columnar portions 35 may be circular.
[0056] The recess 34 where the column portion 35 is located is a part of the intermediate member 30 that has good heat dissipation from the ceramic body 10. Therefore, by arranging multiple column portions 35 in the recess 34, heat can be dispersed. In addition, because the cross-sectional shape of the column portion 35 is circular, stress or heat can be dispersed compared to other shapes. Therefore, the sample holder 100 has excellent heat uniformity.
[0057] As shown in Figure 8, the upper end of the column 35 closest to the center of the intermediate member 30 may be closer to the fourth surface 30b than the upper end of the column 35 closest to the outer circumference of the intermediate member 30. This makes it easier for the distance between the second surface 10b of the ceramic body 10 and the upper end of the column 35 of the intermediate member 30 to become uniform across the multiple column 35 when the sample holder 100 is heated and the third surface 30a is curved in a convex shape. Therefore, the sample holder 100 has excellent heat uniformity.
[0058] As shown in Figure 8 or Figure 9, the surface 35a of the column portion 35 facing the second surface 10b (see Figure 1) of the ceramic body 10 may be inclined upward toward the outer periphery of the third surface 30a. In other words, the opposing surface 35a may be inclined in a direction such that the distance from the second surface 10b decreases toward the outer periphery of the third surface 30a.
[0059] With this configuration, when the sample holder 100 is heated and the third surface 30a is curved in a convex shape, the opposing surface 35a approaches parallel to the second surface 10b, so that the gap between the second surface 10b of the ceramic body 10 and the opposing surface 35a of the column portion 35 of the intermediate member 30 becomes uniform. Therefore, the sample holder 100 has excellent heat uniformity.
[0060] Furthermore, it is preferable that the corner portion 36 located at the lower end of the column portion 35 has an R shape. This corner portion 36 is the part where the circumferential surface 35b of the column portion 35 and the bottom surface of the recess 34 come into contact.
[0061] Thus, because the corners 36 of the column portion 35 have an R shape, the concentration of stress at these corners 36 can be reduced, thereby improving the strength of the intermediate member 30 near the column portion 35. Furthermore, because the localized high temperature near the corners 36 can be reduced, the sample holder 100 has excellent heat uniformity.
[0062] As shown in Figure 11, the columnar portion 35 may have a grid-like structure in plan view. In this case as well, since heat can be dispersed by the columnar portion 35, the sample holder 100 has excellent heat uniformity.
[0063] Furthermore, while Figures 8 and 9 show an example where the bottom surface of the recess 34 of the third surface 30a is a concave curved surface, the example is not limited to this. For example, the bottom surface of the recess 34 may be a flat surface.
[0064] (Fifth Embodiment) Figure 12 is a schematic cross-sectional view showing the sample holder 100 according to the fifth embodiment. Note that in Figure 12, the fixing member 50 is omitted for ease of understanding.
[0065] As shown in Figure 12, the second surface 10b of the ceramic body 10 may be a concave curved surface. With this configuration, a wide space can be formed between the inner circumference of the second surface 10b of the ceramic body 10 and the inner circumference of the third surface 30a of the intermediate member 30. In addition, because of the excellent adhesion with the outer circumference of the intermediate member 30, the sample holder 100 has excellent heat uniformity.
[0066] As shown in Figure 12, the concave surface is positioned such that the thickness of the ceramic body 10 increases from the center of the second surface 10b of the ceramic body 10 toward the outer periphery. The maximum depth of the concave surface, i.e., the dimension from the outer edge of the second surface 10b in the thickness direction of the ceramic body 10 to the most recessed position of the concave surface, may be, for example, 5 to 100 μm. The most recessed position of the concave surface may be located at the center of the second surface 10b. The radius of curvature of the concave surface at the center of the second surface 10b may be larger than the radius of curvature of the concave surface at a position closer to the outer periphery than the center of the second surface 10b.
[0067] 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 and a second surface located opposite the first surface, and having electrodes inside; a base plate that supports the ceramic body; an intermediate member located between the ceramic body and the base plate; and a fixing member that fixes the ceramic body and the base plate, wherein the intermediate member has a lower coefficient of thermal expansion and thermal conductivity than the ceramic body, and has a third surface facing the second surface, and the third surface has a protrusion on its outer circumference that contacts the second surface of the ceramic body. (2) The sample holder according to (1), wherein the inner circumference of the third surface is a concave curved surface. (3) The sample holder according to (1) or (2), wherein the protrusion is annular in plan view. (4) The sample holder according to any one of (1) to (3), wherein the intermediate member is formed from a single material. (5) The sample holder according to any one of (1) to (4), wherein the surface of the protrusion facing the second surface is inclined upward toward the outer edge. (6) The sample holder according to any one of (1) to (5), wherein the third surface has a recess on its inner circumference. (7) The sample holder according to (6), wherein the third surface has a plurality of columnar portions in the recess that extend toward the second surface. (8) The sample holder according to any one of (1) to (7), wherein the second surface is a concave curved surface. (9) The sample holder according to any one of (1) to (8), further comprising a buffer member located between the intermediate member and the base plate.
[0068] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. Indeed, the embodiments described above can be embodied in a variety of forms. 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.
[0069] 10 Ceramic body 10a First surface 10b Second surface 11 Electrode 20 Base plate 30 Intermediate member 30a Third surface 30b Fourth surface 32 Protrusion 32a Opposing surface 34 Recess 35 Columnar part 40 Cushioning member 50 Fixing member 100 Sample holder W Workpiece
Claims
1. A sample holder comprising: a ceramic body having an electrode inside, having a first surface which is a sample holding surface and a second surface located opposite the first surface; a base plate that supports the ceramic body; an intermediate member located between the ceramic body and the base plate; and a fixing member that fixes the ceramic body and the base plate, wherein the intermediate member has a lower coefficient of thermal expansion and thermal conductivity than the ceramic body, has a third surface facing the second surface, and the third surface has a protrusion on its outer circumference that contacts the second surface of the ceramic body.
2. The sample holder according to claim 1, wherein the third surface has a concave curved inner surface.
3. The sample holder according to claim 1 or 2, wherein the protrusion is annular in plan view.
4. The sample holder according to any one of claims 1 to 3, wherein the intermediate member is formed from a single member.
5. The sample holder according to any one of claims 1 to 4, wherein the surface of the protrusion facing the second surface is inclined upward toward the outer edge.
6. The sample holder according to any one of claims 1 to 5, wherein the third surface has a recess in its inner circumference.
7. The sample holder according to claim 6, wherein the third surface has a plurality of columnar portions extending toward the second surface in the recess.
8. The sample holder according to any one of claims 1 to 7, wherein the second surface is a concave curved surface.
9. The sample holder according to any one of claims 1 to 8, further comprising a buffer member located between the intermediate member and the base plate.