Sample holder

Abstract

A sample holder according to the present disclosure comprises a main body, a first electrode, a second electrode, and a connecting part. The main body is formed from ceramic and has a holding surface for an object to be processed. The first electrode is located inside the main body. The second electrode is located inside the main body and is physically and electrically connected to a power supply terminal. The connecting part electrically connects the first electrode and the second electrode. The connecting part has a conductor layer and via conductors. The via conductors include a plurality of first via conductors and a plurality of second via conductors. The conductor layer, the plurality of first via conductors, and the plurality of second via conductors are arranged along the thickness direction of the main body in the order of the plurality of first via conductors, the conductor layer, and the plurality of second via conductors from the side close to the holding surface of the main body. The plurality of first via conductors and the plurality of second via conductors are positioned so as not to overlap each other when viewed from a perpendicular perspective looking toward the holding surface. The plurality of second via conductors are located farther outward than the power supply terminal when viewed from a perpendicular perspective looking toward the holding surface.

Description

Sample holder

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

[0002] In the process of manufacturing semiconductor parts, a sample holder is used to hold a workpiece, such as a semiconductor wafer, that is to be subjected to various processes. One known sample holder is an electrostatic chuck (see Patent Document 1), which includes a ceramic dielectric substrate, a conductor layer located inside the dielectric substrate, electrode terminals located on the backside thereof, and a connector that electrically connects the conductor layer and the electrode terminals.

[0003] Patent No. 7448060

[0004] A sample holder according to one aspect of the present disclosure includes a main body, a first electrode, a second electrode, and a connection portion. The main body is made of ceramic and has a holding surface for a workpiece. The first electrode is located inside the main body. The second electrode is located inside the main body and is physically and electrically connected to a power supply terminal. The connection portion electrically connects the first electrode and the second electrode. The connection portion includes a conductor layer and via conductors. The via conductors include a plurality of first via conductors and a plurality of second via conductors. The conductor layer, the plurality of first via conductors, and the plurality of second via conductors are arranged along the thickness direction of the main body in the order of the plurality of first via conductors, the conductor layer, and the plurality of second via conductors, from the side closest to the holding surface of the main body. The plurality of first via conductors and the plurality of second via conductors are positioned without overlapping each other when viewed in a perspective direction perpendicular to the holding surface. The plurality of second via conductors are positioned outside the power supply terminal when viewed in a perspective direction perpendicular to the holding surface.

[0005] FIG. 1 is a cross-sectional view showing an example of the configuration of a sample holder according to the first embodiment. FIG. 2A is an enlarged cross-sectional view of region R shown in FIG. 1. FIG. 2B is a cross-sectional view showing another example. FIG. 3 is a perspective view showing an example of the configuration of a connection portion according to the first embodiment. FIG. 4 is a planar perspective view showing an example of the configuration of a connection portion according to the first embodiment. FIG. 5A is a cross-sectional view showing an example of a conductor layer according to the first embodiment. FIG. 5B is a planar perspective view showing another example of the connection portion according to the first embodiment. FIG. 5C is a cross-sectional view showing part X-X of FIG. 5B. FIG. 5D is a cross-sectional view of the conductor layer at part X-X of FIG. 5B. FIG. 6 is a planar perspective view showing an example of the configuration of a connection portion according to the second embodiment. FIG. 7 is a planar perspective view showing another example of the configuration of a connection portion according to the second embodiment. FIG. 8 is a cross-sectional view showing an example of the configuration of a sample holder according to the third embodiment. FIG. 9 is a cross-sectional view showing an example of the configuration of a sample holder according to the fourth embodiment. FIG. 10 is a cross-sectional view showing an example of the configuration of a sample holder according to the fifth embodiment.

[0006] Hereinafter, a mode for carrying out a sample holder according to the present disclosure (hereinafter referred to as an "embodiment") will be described in detail with reference to the drawings. Note that the present disclosure is not limited to this embodiment. Furthermore, each embodiment can be appropriately combined within the scope of not causing any contradiction in the processing content. Furthermore, the same parts in each of the following embodiments will be given the same reference numerals, and duplicated explanations will be omitted.

[0007] Furthermore, in the following embodiments, expressions such as "constant," "orthogonal," "perpendicular," or "parallel" may be used, but these expressions do not necessarily mean "constant," "orthogonal," "perpendicular," or "parallel" in the strict sense. In other words, the above expressions allow for deviations due to, for example, manufacturing precision or installation precision.

[0008] In addition, for ease of understanding, the drawings referred to below may show an orthogonal coordinate system in which the X-axis, Y-axis, and Z-axis directions are defined as being orthogonal to each other, and the Z-axis positive direction is the vertically upward direction. Furthermore, the direction of rotation about the vertical axis may be referred to as the θ direction.

[0009] Patent Document 1 discloses an electrostatic chuck including a ceramic dielectric substrate, a conductor layer located inside the dielectric substrate, an electrode terminal located on the back surface thereof, and a connection portion that electrically connects the conductor layer and the electrode terminal. The connection portion includes flat pad portions and columnar via portions, and the pad portions and via portions are alternately arranged along the thickness direction of the dielectric substrate.

[0010] However, in the electrostatic chuck described in Patent Document 1, the via portion is provided at a position overlapping the electrode terminal in a plan view. Therefore, heat from the electrode terminal is easily transferred to the via portion when power is supplied. If heat is easily transferred to the via portion, the vicinity of the via portion of the dielectric substrate may be locally heated, which may reduce the thermal uniformity of the dielectric substrate.

[0011] Therefore, it is hoped that a sample holder with excellent thermal uniformity can be realized by overcoming the above-mentioned problems.

[0012] First Embodiment First, the configuration of a sample holder 1 according to a first embodiment will be described with reference to FIG. 1. FIG. 1 is a cross-sectional view showing an example of the configuration of the sample holder 1 according to the first embodiment. In the following description, an example is shown in which the sample holder 1 is used as an electrostatic chuck that attracts a workpiece A, but the sample holder 1 of the present disclosure may be used for purposes other than an electrostatic chuck. For example, the sample holder 1 may be used as a heater that heats the workpiece A. Furthermore, the sample holder 1 may be used in a plasma processing apparatus that processes the workpiece A with plasma.

[0013] 1, the sample holder 1 includes a main body 100, a first electrode 110, a second electrode 120, and a connection portion 140. The sample holder 1 may further include a base plate 200 and a bonding layer 300. The sizes of these components may be the same as those of conventionally known sample holders, for example.

[0014] The main body 100 is made of ceramic. The main body 100 may be made by molding a ceramic-containing raw material into a flat plate shape, for example, a substantially circular plate shape. The main body 100 may be made of, for example, aluminum oxide (Al ２ O ３), aluminum nitride (AlN), or yttria (Y ２ O ３ ) may be contained as a main component.

[0015] The main body 100 has, for example, a holding surface 100a and a back surface 100b. The holding surface 100a is a surface that supports a workpiece A, such as a semiconductor wafer. The back surface 100b is located on the opposite side of the holding surface 100a. The back surface 100b is a surface that is bonded to the base plate 200 via a bonding layer 300, which will be described later.

[0016] The first electrode 110 is located inside the main body 100. The first electrode 110 is a thin, flat conductive layer. The first electrode 110 is located, for example, parallel to the holding surface 100a of the main body 100.

[0017] The first electrode 110 may be made of a conductor whose main component is a metal such as molybdenum (Mo), platinum (Pt), or tungsten (W). When a voltage is applied to the first electrode 110 from the outside via a connection part 140 (described later), a Coulomb force is generated between the holding surface 100a and the workpiece A, thereby attracting and holding the workpiece A.

[0018] Although an example in which two first electrodes 110 are provided is shown here, the number of first electrodes 110 is not limited to this. For example, only one first electrode 110 may be provided.

[0019] The second electrode 120 is located inside the main body 100. The second electrode 120 is a thin, flat conductive layer, and is provided to correspond to the first electrode 110. The second electrode 120 is located, for example, parallel to the holding surface 100a of the main body 100.

[0020] A power supply terminal 150 is electrically and physically connected to the second electrode 120. In the first embodiment, a predetermined amount of power is supplied to the second electrode 120 from an external power source (not shown) via the power supply terminal 150 through a power supply line 15. The second electrode 120 may be made of a conductor containing a metal such as molybdenum, platinum, or tungsten as its main component. The power supply line 15 is a conductive metal member that is provided in the base plate 200 and extends to the outside through a through hole (not shown). A cylindrical insulating member, for example, may be provided between the inner surface of the through hole and the power supply line 15.

[0021] The connection portion 140 is located inside the main body portion 100, and electrically connects the first electrode 110 and the second electrode 120. The detailed configuration of the connection portion 140 and the surrounding area will be described later.

[0022] A space may be formed between the main body 100 and the workpiece A. Helium gas for temperature adjustment is supplied to the space from the outside through a gas hole (not shown). By providing helium gas between the main body 100 and the workpiece A, the thermal resistance between them is adjusted, thereby maintaining the temperature of the workpiece A at an appropriate temperature. Note that the temperature adjustment gas supplied to the space may be a type of gas other than helium.

[0023] The base plate 200 is a substantially disk-shaped member that supports the main body 100. The base plate 200 is bonded to the rear surface 100b of the main body 100 via a bonding layer 300. The base plate 200 is formed of a metal such as aluminum. The surface of the base plate 200 may be covered with an insulating film such as an alumina sprayed film.

[0024] A coolant flow path 210 for flowing a coolant is formed inside the base plate 200. The coolant is supplied to the coolant flow path 210 from the outside, thereby cooling the base plate 200.

[0025] The bonding layer 300 is a layer provided between the main body 100 and the base plate 200, and bonds them together. The bonding layer 300 is formed by hardening an adhesive made of an insulating material. For example, a silicone-based adhesive can be used as such an adhesive.

[0026] Next, the configuration of the connection portion 140 and its surrounding area according to the first embodiment will be described with reference to FIGS. 2A to 4. FIG. 2A is an enlarged cross-sectional view of region R shown in FIG. 1. FIG. 2B is a cross-sectional view showing another example. FIG. 3 is a perspective view showing an example of the configuration of the connection portion 140 according to the first embodiment. FIG. 4 is a planar perspective view showing an example of the configuration of the connection portion 140 according to the first embodiment. For ease of understanding, the bonding layer 300 and the base plate 200 are omitted from FIGS. 2A and 2B.

[0027] Connection portion 140 has a conductor layer 141 and via conductors 143 and 144. Conductor layer 141 is a member that is circular in plan view and is positioned parallel to first electrode 110 and second electrode 120. Conductor layer 141 may be made of a conductor whose main component is a metal such as molybdenum, platinum, or tungsten.

[0028] The via conductors 143 and 144 are, for example, positioned perpendicular to the conductor layer 141. The via conductors 143 and 144 may be made of a conductor whose main component is a metal such as molybdenum, platinum, or tungsten.

[0029] The via conductors 143, 144 include a plurality of first via conductors 143 and a plurality of second via conductors 144. In the connection portion 140, the conductor layer 141 and the via conductors 143, 144 are arranged along the thickness direction of the main body portion 100 (see FIG. 1 ). For example, in the connection portion 140, the conductor layer 141 and the via conductors 143, 144 may be arranged alternately along the thickness direction of the main body portion 100 (see FIG. 1 ).

[0030] Specifically, the conductor layer 141, the plurality of first via conductors 143 and the plurality of second via conductors 144 are arranged along the thickness direction of the main body portion 100 in the order of the plurality of first via conductors 143, the conductor layer 141 and the plurality of second via conductors 144 from the side closest to the holding surface 100a of the main body portion 100.

[0031] The first via conductor 143 electrically connects the first electrode 110 and the conductor layer 141. The second via conductor 144 electrically connects the conductor layer 141 and the second electrode 120.

[0032] When viewed perpendicularly toward the holding surface 100a, the plurality of first via conductors 143 and the plurality of second via conductors 144 are positioned without overlapping each other. As a result, when viewed perpendicularly toward the holding surface 100a, the heat transmitted through the second via conductors 144 and the heat transmitted through the first via conductors 143 do not concentrate in one place, and the main body 100 has excellent thermal uniformity.

[0033] As shown in FIG. 4, the second via conductors 144 according to the first embodiment are positioned outside the power supply terminals 150 when viewed perpendicularly toward the holding surface 100a.

[0034] With this configuration, the heat path from the power supply terminal 150 to the second via conductor 144 can be made longer than when the second via conductor 144 is provided at a position overlapping the power supply terminal 150. This makes it difficult for heat to be transferred to the second via conductor 144, reducing local heating of the areas of the main body 100 near the via conductors 143 and 144. Therefore, the sample holder 1 has excellent thermal uniformity.

[0035] Similarly, the plurality of first via conductors 143 may also be positioned outside the power supply terminal 150 when viewed perpendicularly toward the holding surface 100a.

[0036] With this configuration, the heat path from the power supply terminal 150 to the first via conductor 143 can be made longer than when the first via conductor 143 is provided at a position overlapping the power supply terminal 150. This makes it difficult for heat to be transferred to the first via conductor 143, reducing localized heating of the areas of the main body 100 near the via conductors 143, 144. Therefore, the sample holder 1 has even better thermal uniformity.

[0037] 2A, a recess 101 is formed on the rear surface 100b of the main body 100. One end of the power supply terminal 150 is held in the recess 101. The power supply terminal 150 is a cylindrical or tubular metal terminal.

[0038] 2B , the second electrode 120 may further have a through-hole 121 penetrating in the thickness direction. In other words, the second electrode 120 may have a circular ring shape in a plan view. The through-hole 121 is formed in the center of the second electrode 120. The inner surface of the through-hole 121 is exposed from the side surface of the recess 101. The inner surface of the through-hole 121 may be connected to an outer surface 150 a of the power supply terminal 150 via a metal film 160.

[0039] With this configuration, heat is transferred horizontally from the power supply terminal 150 to the second electrode 120, and the heat is easily dispersed from the center to the ends of the second electrode 120. As a result, heat is less likely to be transferred from the power supply terminal 150 to the via conductors 143 and 144, and the areas of the main body 100 near the via conductors 143 and 144 are less likely to be heated locally.

[0040] The power supply terminal 150 may further have a flange portion 151 that protrudes outward from an outer surface 150a of the power supply terminal 150. The flange portion 151 is in contact with the rear surface 100b of the main body 100.

[0041] With this configuration, the heat from the power supply terminal 150 can be dispersed to the flange portion 151, making it difficult for heat to be transferred from the power supply terminal 150 to the via conductors 143, 144, and the areas of the main body 100 near the via conductors 143, 144 are less likely to be heated locally.

[0042] Next, the arrangement of the via conductors 143 and 144 according to the first embodiment will be described with reference to FIG.

[0043] As shown in FIG. 4 , a plurality (here, two) of first via conductors 143 and a plurality (here, two) of second via conductors 144 may be arranged at equal intervals along the circumferential direction of the conductor layer 141 .

[0044] With this configuration, the conductor layer 141 has excellent thermal uniformity compared to a case where the first via conductors 143 and the second via conductors 144 are not arranged at equal intervals. Therefore, the main body 100 is less likely to be locally heated. In addition, the conductor layer 141 is less likely to delaminate.

[0045] The cross-sectional areas of the plurality of first via conductors 143 and the plurality of second via conductors 144 may be the same.

[0046] With this configuration, the heat generated from the conductor layer 141 is uniform compared to when the cross-sectional area of ​​the first via conductor 143 is different from the cross-sectional area of ​​the second via conductor 144, and therefore the main body 100 has excellent thermal uniformity. In addition, the conductor layer 141 is less likely to delaminate.

[0047] 4 , a region outside a virtual circle circumscribing the plurality of first via conductors 143 or the plurality of second via conductors 144 and inside a virtual circle inscribing the plurality of first via conductors 143 or the plurality of second via conductors 144 is defined as a virtual ring region V. In this case, the plurality of first via conductors 143 and the plurality of second via conductors 144 may be located within the virtual ring region V.

[0048] With this configuration, the heat generating portion of the conductor layer 141 is ring-shaped when viewed perpendicularly toward the holding surface 100a, which reduces the concentration of stress or heat in one location, and therefore the sample holder 1 has excellent durability and thermal uniformity.

[0049] The center C1 of the imaginary circle circumscribing the plurality of first via conductors 143 and the center C2 of the imaginary circle circumscribing the plurality of second via conductors 144 may overlap.

[0050] With this configuration, the heat transfer path from the power supply terminal 150 becomes symmetrical with respect to the centers C1 and C2 of the imaginary circle, and the heat is dispersed more evenly. Therefore, the main body 100 has excellent thermal uniformity.

[0051] 4, the center C3 of the conductor layer 141 may overlap with the center C1 of an imaginary circle circumscribing the plurality of first via conductors 143 or the center C2 of an imaginary circle circumscribing the plurality of second via conductors 144. With this configuration, the heat distribution in the conductor layer 141 becomes symmetrical, making it difficult for the conductor layer 141 to be locally heated, and therefore making it difficult for interlayer isolation to occur.

[0052] Next, the cross-sectional shape of the conductor layer 141 according to the first embodiment will be described with reference to Fig. 5A. Fig. 5A is a cross-sectional view showing an example of the conductor layer 141 according to the first embodiment.

[0053] 5A , the thickness t1 of the central portion 141a of the conductor layer 141 in a cross-sectional view may be smaller than the thickness t2 of the end portion 141b. Specifically, the thickness of the conductor layer 141 may increase from the central portion 141a toward the end portion 141b.

[0054] When the thickness t1 of the central portion 141a is smaller than the thickness t2 of the end portion 141b, heat transferred from the second via conductor 144 (see FIG. 3) to the conductor layer 141 is more easily transmitted to the first via conductor 143 through the end portion 141b of the conductor layer 141. This lengthens the heat path from the second via conductor 144 to the first via conductor 143, reducing localized heating of the main body 100 near the first via conductor 143. This further improves the sample holder 1's thermal uniformity. Furthermore, because the central portion 141a of the conductor layer 141 is less likely to be locally heated, delamination is less likely to occur. In particular, increasing the thickness of the portions of the conductor layer 141 connected to the via conductors 143 and 144 minimizes heat generation.

[0055] As described above, the plurality of second via conductors 144 in the sample holder 1 according to the first embodiment are located outside the power supply terminals 150 when viewed perpendicularly toward the holding surface 100a. This configuration makes it possible to lengthen the heat path from the power supply terminals 150 to the second via conductors 144 compared to when the second via conductors 144 are provided at positions overlapping the power supply terminals 150. This makes it difficult for heat to be transferred from the power supply terminals 150 to the second via conductors 144, thereby reducing localized heating of the areas of the main body 100 near the via conductors 143 and 144. Therefore, the sample holder 1 has excellent thermal uniformity.

[0056] Although an example in which the number of first via conductors 143 and the number of second via conductors 144 are two each has been shown here, the number of first via conductors 143 and second via conductors 144 is not limited to this. Furthermore, the number of first via conductors 143 and second via conductors 144 or their respective cross-sectional areas may be different.

[0057] Here, an example in which the number of first via conductors 143 and the number of second via conductors 144 are three will be described with reference to Figures 5B to 5D. Figure 5B is a planar perspective view showing another example of connection portion 140 according to the first embodiment. Figure 5C is a cross-sectional view showing the X-X portion of Figure 5B. Figure 5D is a cross-sectional view of conductor layer 141 at the X-X portion of Figure 5B.

[0058] When the number of via conductors 143 and 144 is three, the heat generation regions on both the front and back surfaces of connection portion 140 are dispersed to three locations compared to when there are two via conductors 143 and 144. Therefore, even if connection portion 140 thermally expands in the planar direction due to heat generation, stress can be dispersed by connection portion 140 expanding evenly without expanding in a specific direction compared to when there are two via conductors 143 and 144. In particular, stress is dispersed most effectively when first via conductor 143 and second via conductor 144 are positioned in equilateral triangles.

[0059] Second Embodiment Fig. 6 is a planar perspective view showing an example of the configuration of the connection portion 140 according to the second embodiment. Fig. 7 is a planar perspective view showing another example of the configuration of the connection portion 140 according to the second embodiment. In the first embodiment, the via conductors 143, 144 have a circular shape in a plan view, and all of the via conductors 143, 144 are arranged at equal intervals in the circumferential direction of the conductor layer 141. However, the shapes and arrangement of the via conductors 143, 144 are not limited to this.

[0060] For example, the via conductors 143 and 144 may have a polygonal shape such as a quadrangular shape in a plan view, or may have a quadrangular shape with rounded corners as shown in FIG.

[0061] 6, only a plurality of (here, two) first via conductors 143 may be arranged at equal intervals in the circumferential direction of the conductor layer 141. Similarly, only a plurality of (here, two) second via conductors 144 may be arranged at equal intervals in the circumferential direction of the conductor layer 141.

[0062] As such, like the connection portion 140 of the first embodiment, the connection portion 140 of the second embodiment has the same cross-sectional area for each of the multiple first via conductors 143 and the multiple second via conductors 144, so the conductor layer 141 has excellent thermal uniformity.

[0063] Third Embodiment Fig. 8 is a cross-sectional view showing an example of the configuration of a sample holder 1 according to a third embodiment. In the first embodiment, an example was shown in which the connection portion 140 had one conductor layer 141, but the number of conductor layers is not limited to this. For example, as shown in Fig. 8, the connection portion 140 may have multiple conductor layers 141 and 142. Specifically, the connection portion 140 may have a first conductor layer 141, a second conductor layer 142, multiple first via conductors 143, multiple second via conductors 144, and multiple third via conductors 145.

[0064] In the connection portion 140, the plurality of conductor layers 141, 142 and the plurality of via conductors 143, 144, 145 may be arranged alternately along the thickness direction of the main body portion 100. For example, the plurality of conductor layers 141, 142 and the plurality of via conductors 143, 144, 145 may be arranged along the thickness direction of the main body portion 100 in the order of the plurality of first via conductors 143, the first conductor layer 141, the plurality of second via conductors 144, the second conductor layer 142, and the plurality of third via conductors 145, from the side closer to the holding surface 100a (see FIG. 1 ) of the main body portion 100.

[0065] The first via conductor 143 may electrically connect the first electrode 110 and the first conductor layer 141. The second via conductor 144 may electrically connect the first conductor layer 141 and the second conductor layer 142. The third via conductor 145 may electrically connect the second conductor layer 142 and the second electrode 120.

[0066] The first conductor layer 141 and the second conductor layer 142 may overlap when viewed in a direction perpendicular to the holding surface 100a.

[0067] Since the via conductors 143, 144, and 145 are arranged vertically, when the positions of the conductor layers 141 and 142 overlap, the positions of the via conductors 143, 144, and 145 can be reversed in the adjacent conductor layers 141 and 142. As a result, the heat distribution becomes more symmetrical in the region sandwiched between the adjacent conductor layers 141 and 142, and the main body 100 has even better thermal uniformity.

[0068] 9 is a cross-sectional view showing an example of the configuration of a sample holder 1 according to a fourth embodiment. In the first embodiment, the second electrode 120 has a through-hole 121 (see FIG. 2B ) and the power supply terminal 150 is inserted into the through-hole 121, but the shape of the second electrode 120 or the arrangement of the power supply terminal 150 are not limited to this.

[0069] 9 , the second electrode 120 may be a plate-like member that is circular in plan view. The second electrode 120 may be positioned so that one main surface is exposed from the recess 101 of the main body 100. Specifically, the second electrode 120 may be positioned so that a central portion of one main surface of the second electrode 120 is exposed from the recess 101. The power supply terminal 150 may be electrically and physically connected to the exposed portion of the second electrode 120. A gap 170 may be located between an outer surface 150 a of the power supply terminal 150 and a side surface of the recess 101 of the main body 100.

[0070] In this manner, the exposed portion (center portion) of the second electrode 120 is electrically and physically connected to the power supply terminal 150, which facilitates heat dispersion from the center toward the ends of the second electrode 120. This makes it difficult for heat to be transferred from the power supply terminal 150 to the via conductors 143 and 144, thereby reducing localized heating of the areas of the main body 100 near the via conductors 143 and 144.

[0071] 10 is a cross-sectional view showing an example of the configuration of a sample holder 1 according to a fifth embodiment. As shown in Fig. 10, a gap 170 may be located between an outer surface 150a of the power supply terminal 150 and a side surface of the recess 101 of the main body 100.

[0072] With this configuration, it is possible to reduce the transfer of heat from the outer surface 150 a of the power supply terminal 150 to the main body 100 , the second electrode 120 or the connection portion 140 via the side surface of the recess 101 .

[0073] The metal film 160 may be located on the bottom and side surfaces of the recess 101. In this way, by having the metal film 160 located not only on the bottom surface but also on the side surfaces of the recess 101, heat from the power supply terminal 150 is also transferred to the side surfaces of the recess 101, which further reduces local heating of the main body 100.

[0074] The present technology can also be configured as follows: (1) A sample holder comprising: a main body portion made of ceramic and having a holding surface for a workpiece; a first electrode located inside the main body portion; a second electrode located inside the main body portion and physically and electrically connected to a power supply terminal; and a connection portion electrically connecting the first electrode and the second electrode, wherein the connection portion has a conductor layer and via conductors, wherein the via conductors include a plurality of first via conductors and a plurality of second via conductors, wherein the conductor layer, the plurality of first via conductors, and the plurality of second via conductors are arranged along a thickness direction of the main body portion in the order of the plurality of first via conductors, the conductor layer, and the plurality of second via conductors, from the side closest to the holding surface of the main body portion, wherein the plurality of first via conductors and the plurality of second via conductors are positioned without overlapping each other when viewed in a see-through direction perpendicular to the holding surface, and wherein the plurality of second via conductors are positioned outside the power supply terminal when viewed in a see-through direction perpendicular to the holding surface. (2) The sample holder according to (1), wherein the plurality of first via conductors are located outside the power supply terminal when viewed in a direction perpendicular to the holding surface. (3) The sample holder according to (1) or (2), wherein, when viewed in a direction perpendicular to the holding surface, the plurality of first via conductors and the plurality of second via conductors are located within a virtual ring region that is outside a virtual circle circumscribing the plurality of first via conductors or the plurality of second via conductors and inside a virtual circle inscribing the plurality of first via conductors or the plurality of second via conductors. (4) The sample holder according to any one of (1) to (3), wherein, when viewed in a direction perpendicular to the holding surface, the center of the virtual circle circumscribing the plurality of first via conductors and the center of the virtual circle circumscribing the plurality of second via conductors overlap. (5) The sample holder according to any one of (1) to (4), wherein the conductor layer has a circular shape when seen through in a direction perpendicular to the holding surface, and the plurality of first via conductors and the plurality of second via conductors are arranged at equal intervals along the circumferential direction of the conductor layer. (6) The sample holder according to any one of (1) to (5), wherein the plurality of first via conductors and the plurality of second via conductors have the same cross-sectional area.(7) The sample holder according to any one of (1) to (6), wherein the conductor layer has a first conductor layer and a second conductor layer, the via conductors include a plurality of first via conductors, a plurality of second via conductors, and a plurality of third via conductors, and the plurality of first via conductors, the first conductor layer, the plurality of second via conductors, the second conductor layer, and the plurality of third via conductors are arranged in this order along the thickness direction of the main body from the side closest to the holding surface of the main body, and the first conductor layer and the second conductor layer overlap when viewed perpendicularly toward the holding surface. (8) The sample holder according to any one of (1) to (7), wherein the thickness of the conductor layer at a center in a cross-sectional view is smaller than the thickness of the end portions in the cross-sectional view. (9) The sample holder according to any one of (1) to (8), wherein the second electrode further has a through hole penetrating in the thickness direction, and the inner surface of the through hole is connected to the outer surface of the power supply terminal via a metal film. (10) The sample holder according to any one of (1) to (9), wherein the power supply terminal further has a flange portion that protrudes outward from the outer surface of the power supply terminal. (11) The sample holder according to any one of (1) to (7), wherein the main body has a recess in a back surface opposite the holding surface, from which a portion of the second electrode is exposed, and the power supply terminal is located in the recess and is connected to the exposed portion of the second electrode. (12) The sample holder according to (11), wherein a gap is located between the outer surface of the power supply terminal and a side surface of the recess.

[0075] The disclosed embodiments should be considered in all respects as illustrative and not restrictive. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0076] REFERENCE SIGNS LIST 1 sample holder 100 main body 100a holding surface 100b back surface 101 recess 110 first electrode 120 second electrode 121 through hole 140 connection portion 141, 142 conductor layer 141a central portion 141b end portion 143, 144, 145 via conductor 150 power supply terminal 150a outer surface 151 flange portion 160 metal film 170 gap 200 base plate 210 coolant flow path 300 bonding layer

Claims

1. A sample holder comprising: a main body made of ceramic and having a holding surface for holding an object to be processed; a first electrode located inside the main body; a second electrode located inside the main body and physically and electrically connected to a power supply terminal; and a connection portion electrically connecting the first electrode and the second electrode, wherein the connection portion has a conductor layer and via conductors, and the via conductors include a plurality of first via conductors and a plurality of second via conductors, and the conductor layer, the plurality of first via conductors, and the plurality of second via conductors are arranged along the thickness direction of the main body in the order of the plurality of first via conductors, the conductor layer, and the plurality of second via conductors, from the side closest to the holding surface of the main body, and the plurality of first via conductors and the plurality of second via conductors are positioned without overlapping each other when viewed perpendicularly towards the holding surface, and the plurality of second via conductors are positioned outside the power supply terminal when viewed perpendicularly towards the holding surface.

2. A sample holder as described in claim 1, wherein the plurality of first via conductors are positioned outside the power supply terminal when viewed perpendicularly toward the holding surface.

3. A sample holder as described in claim 1 or 2, wherein when viewed perpendicularly toward the holding surface, the region that is outside a virtual circle circumscribing the plurality of first via conductors or the plurality of second via conductors and inside a virtual circle inscribing the plurality of first via conductors or the plurality of second via conductors is defined as a virtual ring region, and the plurality of first via conductors and the plurality of second via conductors are located within the virtual ring region.

4. A sample holder as described in any one of claims 1 to 3, wherein when viewed perpendicularly toward the holding surface, the center of an imaginary circle circumscribing the plurality of first via conductors overlaps with the center of an imaginary circle circumscribing the plurality of second via conductors.

5. A sample holder as described in any one of claims 1 to 4, wherein when viewed perpendicularly toward the holding surface, the conductor layer has a circular shape, and the plurality of first via conductors and the plurality of second via conductors are arranged at equal intervals along the circumferential direction of the conductor layer.

6. A sample holder according to any one of claims 1 to 5, wherein the plurality of first via conductors and the plurality of second via conductors have the same cross-sectional area.

7. A sample holder according to any one of claims 1 to 6, wherein the conductor layer has a first conductor layer and a second conductor layer, the via conductors include a plurality of first via conductors, a plurality of second via conductors, and a plurality of third via conductors, the plurality of first via conductors, the first conductor layer, the plurality of second via conductors, the second conductor layer, and the plurality of third via conductors are arranged in this order along the thickness direction of the main body from the side closest to the holding surface of the main body, and the first conductor layer and the second conductor layer overlap when viewed perpendicularly towards the holding surface.

8. A sample holder according to any one of claims 1 to 7, wherein the thickness of the central portion of the conductor layer in a cross-sectional view is smaller than the thickness of the end portions in the cross-sectional view.

9. A sample holder according to any one of claims 1 to 8, wherein the second electrode further has a through-hole penetrating in the thickness direction, and the inner surface of the through-hole is connected to the outer surface of the power supply terminal via a metal film.

10. A sample holder according to any one of claims 1 to 9, wherein the power supply terminal further has a flange portion that protrudes outward from the outer surface of the power supply terminal.

11. A sample holder according to any one of claims 1 to 8, wherein the main body has a recess on the back surface opposite the holding surface, through which a portion of the second electrode is exposed, and the power supply terminal is located in the recess and is connected to the exposed portion of the second electrode.

12. The sample holder according to claim 11, wherein a gap is located between the outer surface of the power supply terminal and the side surface of the recess.

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