Electrostatic chuck

Abstract

This electrostatic chuck has a ceramic substrate, a base plate, and an embedded member. The ceramic substrate has: a first surface on which an object to be treated is placed; a second surface positioned opposite to the first surface; and a first flow passage passing through the first surface and the second surface. The base plate is joined to the second surface of the ceramic substrate and has a through-hole at a position corresponding to at least the first flow passage. The embedded member is positioned inside the through-hole, and has a porous body facing the first flow passage and a second flow passage in communication with the first flow passage via the porous body. The first flow passage and the second flow passage are positioned to be spaced apart from each other when viewed in a plan view.

Description

[Technical Field]

[0001] The disclosed embodiments relate to an electrostatic chuck. [Background technology]

[0002] In the process of manufacturing semiconductor parts, electrostatic chucks are used to hold workpieces, such as semiconductor wafers, that are to be subjected to plasma processing. The electrostatic chuck is configured, for example, by bonding a ceramic substrate with an electrode embedded therein to a metal base plate. The electrostatic chuck has a flow path formed therein for supplying a heat transfer gas for temperature control to the workpiece placed on the electrostatic chuck.

[0003] Also, from the viewpoint of suppressing the intrusion of plasma into the flow path, an electrostatic chuck in which a porous body is disposed in the flow path has been proposed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-165223 Summary of the Invention

[0005] An electrostatic chuck according to one aspect of the embodiment includes a ceramic substrate, a base plate, and an embedding member. The ceramic substrate has a first surface on which a workpiece is placed, a second surface opposite the first surface, and a first flow path penetrating the first and second surfaces. The base plate is bonded to the second surface of the ceramic substrate and has a through hole at least at a position corresponding to the first flow path. The embedding member is located within the through hole and has a porous body facing the first flow path and a second flow path communicating with the first flow path via the porous body. The first flow path and the second flow path are positioned apart in a plan view. [Brief explanation of the drawings]

[0006] [Figure 1]FIG. 1 is a perspective view showing the configuration of an electrostatic chuck according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a cross section of the electrostatic chuck of FIG. [Figure 3] FIG. 3 is a plan view showing an example of the configuration of the ceramic substrate of the electrostatic chuck of FIG. 1 as viewed from above. [Figure 4] FIG. 4 is a schematic diagram showing a cross section of an electrostatic chuck according to a first modification of the embodiment. [Figure 5] FIG. 5 is a plan view showing an example of the configuration of the ceramic substrate of the electrostatic chuck of FIG. 4 as viewed from above. [Figure 6] FIG. 6 is a schematic diagram showing a cross section of an electrostatic chuck according to a second modification of the embodiment. [Figure 7] FIG. 7 is a plan view showing an example of the configuration of the ceramic substrate of the electrostatic chuck of FIG. 6 as viewed from above. [Figure 8] FIG. 8 is a schematic diagram showing a cross section of an electrostatic chuck according to a third modification of the embodiment. [Figure 9] FIG. 9 is a cross-sectional view of an embedded member included in the electrostatic chuck of FIG. [Figure 10] FIG. 10 is a schematic diagram showing a cross section of an electrostatic chuck according to a fourth modification of the embodiment. [Figure 11] FIG. 11 is a cross-sectional view of an embedded member included in the electrostatic chuck of FIG. [Figure 12] FIG. 12 is a schematic diagram showing a cross section of an electrostatic chuck according to a fifth modification of the embodiment. [Figure 13] FIG. 13 is a cross-sectional view of an embedded member included in the electrostatic chuck of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments of an electrostatic chuck disclosed herein will be described with reference to the accompanying drawings. Note that the present disclosure is not limited to the embodiments described below. It should be noted that the drawings are schematic, and the dimensional relationships and ratios of elements may differ from the actual situation. Furthermore, the dimensional relationships and ratios may differ between the drawings.

[0008] 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, installation precision, etc.

[0009] <Embodiment> Fig. 1 is a perspective view showing the configuration of an electrostatic chuck 100 according to the embodiment. The electrostatic chuck 100 shown in Fig. 1 has a structure in which a ceramic substrate 110 and a base plate 120 are joined together.

[0010] The ceramic substrate 110 utilizes electrostatic force to attract an object to be processed, such as a semiconductor wafer.

[0011] The base plate 120 is a support member that supports the ceramic substrate 110. The base plate 120 is attached to, for example, a semiconductor manufacturing device, and causes the electrostatic chuck 100 to function as a semiconductor holding device that holds an object to be processed, such as a semiconductor wafer.

[0012] Fig. 2 is a schematic diagram showing a cross section of the electrostatic chuck 100 of Fig. 1. As described above, the electrostatic chuck 100 is configured by bonding the ceramic substrate 110 and the base plate 120 together.

[0013] The ceramic substrate 110 is a member formed into a substantially circular disk shape from a ceramic-containing raw material. The ceramic substrate 110 contains, for example, aluminum oxide (Al2O3), aluminum nitride (AlN), yttria (Y2O3), cordierite, silicon carbide (SiC), silicon nitride (Si3N4), or the like as its main component.

[0014] The ceramic substrate 110 has a first surface 110a on which a workpiece such as a semiconductor wafer is placed, and a second surface 110b opposite to the first surface 110a. The workpiece placed on the first surface 110a of the ceramic substrate 110 is processed by generating plasma above the first surface 110a. The plasma can be generated by applying high-frequency power to opposing electrodes to excite a gas.

[0015] An electrode 111 is provided inside the ceramic substrate 110. The electrode 111 is, for example, an electrostatic attraction electrode, and is a conductive member containing a metal such as platinum, tungsten, or molybdenum. When a voltage is applied to the electrode 111, the electrode 111 generates an electrostatic force, causing the workpiece to be attracted to the first surface 110a of the ceramic substrate 110.

[0016] The base plate 120 is bonded to the second surface 110b of the ceramic substrate 110. The base plate 120 may be bonded to the second surface 110b via, for example, a bonding material. As the bonding material, for example, an adhesive such as a silicone resin can be used.

[0017] The base plate 120 is a circular metal member, and may be made of aluminum or stainless steel, for example.

[0018] The base plate 120 may have an internal space 121. The space 121 may be used as a coolant passage for passing a cooling medium such as cooling water or cooling gas. The base plate 120 may also function as a high-frequency electrode to which high-frequency power for generating plasma is applied.

[0019] As shown in FIG. 2, the ceramic substrate 110 has a plurality of first flow paths 112 formed therein, which penetrate the first surface 110a and the second surface 110b.

[0020] Furthermore, a through-hole 122 is formed in the base plate 120 at a position corresponding to at least the first flow path 112, and an embedding member 130 is disposed in the through-hole 122.

[0021] The embedding member 130 is a cylindrical member made of an insulating material such as aluminum oxide (Al2O3). When the recess 113 is provided on the second surface 110b of the ceramic substrate 110, the embedding member 130 may protrude toward the ceramic substrate 110 beyond the upper surface of the base plate 120 (i.e., the surface bonded to the second surface 110b) and fit into the recess 113. This shortens the length of the first flow path 112 at a position corresponding to the recess 113 of the ceramic substrate 110, thereby suppressing the generation of plasma in the first flow path 112.

[0022] The embedded member 130 has a porous body 131 at the end on the first flow path 112 side. By positioning the porous body 131 at the end on the first flow path 112 side, when plasma is generated above the first surface 110a of the ceramic substrate 110, it is possible to reduce the problem of the plasma passing through the first flow path 112 and reaching the base plate 120 side.

[0023] The porous body 131 is, for example, an alumina porous body or another ceramic porous body. The porous body 131 only needs to have pores to the extent that gas can flow through it, and the porosity of the porous body 131 is, for example, 40% or more and 60% or less.

[0024] Furthermore, the embedding member 130 is formed with a second flow path 132 that communicates with the first flow path 112 via the porous body 131. The second flow path 132 and the first flow path 112 form a gas flow path that continues from the lower surface of the base plate 120 through the porous body 131 to the upper surface (first surface 110a) of the ceramic substrate 110. A heat transfer gas such as helium may be flowed through the second flow path 132 and the first flow path 112. By flowing the heat transfer gas through the second flow path 132 and the first flow path 112, the heat transfer gas is supplied to the back surface of the workpiece placed on the first surface 110a of the ceramic substrate 110, improving the heat transfer coefficient between the workpiece and the ceramic substrate 110.

[0025] The first flow path 112 and the second flow path 132 are located at positions where they do not overlap with each other in a plan view (that is, when viewed from a direction perpendicular to the first surface 110a).

[0026] Fig. 3 is a plan view showing an example of the configuration of the ceramic substrate 110 included in the electrostatic chuck 100 of Fig. 1, as viewed from above. In Fig. 3, the first surface 110a of the ceramic substrate 110 is shown in a disk shape. The multiple first flow paths 112 are located at positions surrounding the second flow path 132 in a plan view (i.e., as viewed from a direction perpendicular to the first surface 110a). In the example of Fig. 3, six first flow paths 112 are located at equal intervals on concentric circles centered on the central axis of one second flow path 132.

[0027] Now, for example, assume that first flow path 112 and second flow path 132 are positioned linearly from the upper surface (first surface 110a) of ceramic substrate 110 to the lower surface of base plate 120. In this case, when plasma is generated above first surface 110a, charged particles in the plasma may enter first flow path 112 while maintaining high energy, and reach porous body 131 or second flow path 132, potentially causing abnormal discharge in porous body 131 or second flow path 132.

[0028] 2 and 3, the first flow path 112 and the second flow path 132 are arranged so as not to overlap each other in a plan view, forming a gas flow path having a structure that bends in a direction parallel to the first surface 110a, i.e., a labyrinth structure. As a result, even if charged particles in the plasma enter the first flow path 112 when plasma is generated above the first surface 110a, they are deactivated by coming into contact with the wall surfaces of the voids in the porous body 131 and the wall surfaces of the second flow path. As a result, the electrostatic chuck 100 according to this embodiment can suppress the occurrence of abnormal discharge in the first flow path and the second flow path.

[0029] Furthermore, by positioning the multiple first flow paths 112 at positions surrounding the second flow path 132 in a plan view, when a heat transfer gas is supplied to the back surface of the workpiece placed on the first surface 110a, the heat transfer gas is dispersed among the first flow paths 112, reducing the gas pressure in each of the first flow paths 112. As a result, the electrostatic chuck 100 according to this embodiment can suppress the occurrence of abnormal discharge in each of the first flow paths 112 due to an increase in the gas pressure of the heat transfer gas.

[0030] <Modification> The number and arrangement of the first flow paths 112 and the second flow paths 132 are not limited to those shown in Figures 2 and 3. Figure 4 is a schematic diagram showing a cross section of an electrostatic chuck 100 according to a first modification of the embodiment.

[0031] 4, the embedded member 130 according to the first modification is formed with a plurality of second flow paths 132 that communicate with the first flow paths 112 via porous bodies 131. The first flow paths 112 and the second flow paths 132 are located at positions that do not overlap with each other in a plan view (i.e., when viewed from a direction perpendicular to the first surface 110a), similar to the first flow paths 112 and the second flow paths 132 shown in FIG.

[0032] FIG. 5 is a plan view showing an example of the configuration of the ceramic substrate 110 included in the electrostatic chuck 100 of FIG. 4, as viewed from above. In FIG. 5, the first surface 110a of the ceramic substrate 110 is shown as a disk. The plurality of second flow paths 132 are positioned to surround the first flow path 112 in a plan view (i.e., as viewed from a direction perpendicular to the first surface 110a). In the example of FIG. 5, four second flow paths 132 are positioned at equal intervals on concentric circles centered on the center position of a line segment connecting two first flow paths 112. By positioning the plurality of second flow paths 132 to surround the first flow path 112 in a plan view, when a heat transfer gas is supplied to the back surface of a workpiece placed on the first surface 110a, the heat transfer gas is dispersed among the second flow paths 132, thereby reducing the gas pressure in each of the second flow paths 132. As a result, the electrostatic chuck 100 according to the first modification can suppress the occurrence of abnormal discharge in each second flow passage 132 due to an increase in the gas pressure of the heat transfer gas.

[0033] Fig. 6 is a schematic diagram showing a cross section of an electrostatic chuck 100 according to Modification 2 of the embodiment. Fig. 7 is a plan view showing an example of the configuration of a ceramic substrate 110 included in the electrostatic chuck 100 shown in Fig. 6, as viewed from above. In Fig. 7, a first surface 110a of the ceramic substrate 110 is shown in a disk shape.

[0034] 6 and 7 , the first flow path 112 and the second flow path 132 according to Modification 2 are provided in the first region and the second region, respectively. The first region where the first flow path 112 is provided and the second region where the second flow path 132 is provided are located in positions that do not overlap each other in a planar perspective (i.e., when viewed from a direction perpendicular to the first surface 110a) and are spaced apart from each other. For example, the first region where the first flow path 112 is provided and the second region where the second flow path 132 is provided are located in positions that do not overlap each other in a planar perspective and are spaced apart from each other along a line L passing through the center of the ceramic substrate 110. By positioning the first flow path 112 and the second flow path 132 in positions that do not overlap each other and are spaced apart from each other in a planar perspective, the thermal expansion of the ceramic substrate 110 and the base plate 120 can be made to be the same direction for the first flow path 112 and the second flow path 132. As a result, according to the electrostatic chuck 100 of the present modified example 2, even when thermal expansion occurs in the ceramic substrate 110 and the base plate 120, it is possible to reduce defects caused by a misalignment of the positional relationship between the first flow passage 112 and the second flow passage 132. Note that, although the examples illustrated in FIGS. 6 and 7 have been described in which the first flow passage 112 and the second flow passage 132 are positioned at positions spaced apart from each other along the straight line L, the direction in which the first flow passage 112 and the second flow passage 132 are spaced apart from each other may be a direction different from the direction along the straight line L.

[0035] 6 and 7, the first flow path 112 may be located on one side of an imaginary line including the center of the embedded member 130 when viewed from above, and the second flow path 132 may be located on the other side. The two-dot chain line shown in Fig. 7 is an imaginary line including the center of the embedded member when viewed from above. This makes it difficult for charged particles to reach the second flow path 132, and reduces the occurrence of abnormal discharge in the second flow path 132.

[0036] Furthermore, in the above embodiment, an example was described in which the second flow path 132 was formed in the cylindrical embedding member 130, but the second flow path 132 may be formed by a plurality of members obtained by dividing the embedding member 130. Other examples of the embedding member 130 are shown in the following Figures 8 to 13.

[0037] Fig. 8 is a schematic view showing a cross section of an electrostatic chuck 100 according to Modification 3 of the embodiment. Fig. 9 is a cross section of an embedding member 130 included in the electrostatic chuck 100 of Fig. 8. Fig. 9 shows a cross section taken along line II in Fig. 8.

[0038] The embedding member 130 shown in FIGS. 8 and 9 is divided into a cylindrical portion 135 and a columnar portion 136 located within the cylindrical portion 135. The cylindrical portion 135 is located along the inner wall of the through-hole 122 of the base plate 120 and has a space therein. The columnar portion 136 is located in the space within the cylindrical portion 135 with a gap between it and the inner circumferential surface of the cylindrical portion 135. The columnar portion 136 may be fixed to the porous body 131 with an adhesive or the like. The second flow path 132 is formed by the inner circumferential surface of the cylindrical portion 135 and the outer circumferential surface of the columnar portion 136. In other words, the space between the inner circumferential surface of the cylindrical portion 135 and the outer circumferential surface of the columnar portion 136 forms the second flow path 132. More specifically, the second flow path 132 is formed in an annular shape surrounding the columnar portion 136 in a planar perspective view (i.e., when viewed from a direction perpendicular to the first surface 110a).

[0039] In this manner, the second flow passage 132 is formed by the inner circumferential surface of the cylindrical portion 135 and the outer circumferential surface of the columnar portion 136. Therefore, even if stress is applied to the cylindrical portion 135 due to, for example, thermal expansion of the base plate 120, the stress is absorbed by the second flow passage 132. Therefore, according to the electrostatic chuck 100 of the third modification, it is possible to reduce performance degradation due to, for example, heat cycles.

[0040] Furthermore, since the second flow path 132 annularly surrounds the cylindrical portion 136, even if the cylindrical portion 135 is deformed by a long-term heat cycle and radial distortion occurs, the cylindrical portion 136 is unlikely to be subjected to an external force that may cause damage. Therefore, the electrostatic chuck 100 according to the third modification can reduce performance degradation due to a heat cycle over the long term.

[0041] Fig. 10 is a schematic view showing a cross section of an electrostatic chuck 100 according to Modification 4 of the embodiment. Fig. 11 is a cross section of an embedding member 130 included in the electrostatic chuck 100 of Fig. 10. Fig. 11 shows a cross section taken along line II-II in Fig. 10.

[0042] The embedding member 130 shown in FIGS. 10 and 11 is divided into a cylindrical portion 135 and a columnar portion 136. The cylindrical portion 135 is located along the inner wall of the through-hole 122 of the base plate 120, has a space therein, and has a groove 135a on its inner circumferential surface extending in the axial direction of the through-hole 122. In other words, the cylindrical portion 135 has a first constant diameter portion (a portion excluding the groove 135a) having the same diameter as the outer circumferential surface of the columnar portion 136, and a first different diameter portion (a portion including the groove 135a) having a different diameter than the outer circumferential surface of the columnar portion 136. The columnar portion 136 is located in the space within the cylindrical portion 135 along the inner circumferential surface of the cylindrical portion 135. The columnar portion 136 may be fixed to the porous body 131 with an adhesive or the like. The second flow path 132 is formed by the inner wall surface of the groove 135a and the outer circumferential surface of the columnar portion 136. In other words, the space between the first different diameter portion of the cylindrical portion 135 (the portion including the groove 135a) and the outer circumferential surface of the columnar portion 136 forms the second flow path 132.

[0043] In this manner, the second flow passage 132 is formed by the inner wall surface of the groove 135a and the outer circumferential surface of the cylindrical portion 136, and therefore, the flow passage area of ​​the second flow passage 132 can be expanded radially outward of the porous body 131, for example, in accordance with the depth of the groove 135a. Therefore, according to the electrostatic chuck 100 of the fourth modification, when a heat transfer gas is supplied to the back surface of a workpiece placed on the first surface 110a, for example, the heat transfer gas can easily flow radially of the porous body 131, and abnormal discharge in the second flow passage 132 can be suppressed.

[0044] The columnar portion 136 may be positioned in the space within the cylindrical portion 135 with a gap between it and the inner circumferential surface of the cylindrical portion 135 .

[0045] Fig. 12 is a schematic view showing a cross section of an electrostatic chuck 100 according to Modification 5 of the embodiment. Fig. 13 is a cross section of an embedding member 130 included in the electrostatic chuck 100 of Fig. 12. Fig. 13 shows a cross section taken along line III-III in Fig. 12.

[0046] The embedding member 130 shown in FIGS. 12 and 13 is divided into a cylindrical portion 135 and a columnar portion 136. The cylindrical portion 135 is located along the inner wall of the through-hole 122 and has a space therein. The columnar portion 136 is located in the space within the cylindrical portion 135 along the inner circumferential surface of the cylindrical portion 135 and has a groove 136a on its outer circumferential surface extending in the axial direction of the through-hole 122. In other words, the columnar portion 136 has a second constant diameter portion (a portion excluding the groove 136a) having the same diameter as the inner circumferential surface of the cylindrical portion 135 and a second different diameter portion (a portion including the groove 136a) having a different diameter from the inner circumferential surface of the cylindrical portion 135. The second flow path 132 is formed by the inner circumferential surface of the cylindrical portion 135 and the inner wall surface of the groove 136a. In other words, the space between the inner circumferential surface of the cylindrical portion 135 and the second different diameter portion (a portion including the groove 136a) forms the second flow path 132.

[0047] In this manner, the second flow path 132 is formed by the inner circumferential surface of the cylindrical portion 135 and the inner wall surface of the groove 136a, thereby maintaining the strength of the cylindrical portion 135, which is susceptible to stress due to thermal expansion of the base plate 120. Therefore, according to the electrostatic chuck 100 of the fifth modification, it is possible to reduce performance degradation due to heat cycles, for example.

[0048] As described above, an electrostatic chuck (e.g., electrostatic chuck 100) according to an embodiment includes a ceramic substrate (e.g., ceramic substrate 110), a base plate (e.g., base plate 120), and an embedding member (e.g., embedding member 130). The ceramic substrate has a first surface (e.g., first surface 110a) on which a workpiece is placed, a second surface (e.g., second surface 110b) opposite the first surface, and a first flow path (e.g., first flow path 112) penetrating the first and second surfaces. The base plate is bonded to the second surface of the ceramic substrate and has a through-hole (e.g., through-hole 122) at a position corresponding to at least the first flow path. The embedding member is located within the through-hole and has a porous body (e.g., porous body 131) facing the first flow path and a second flow path (e.g., second flow path 132) communicating with the first flow path via the porous body. The first flow path and the second flow path are spaced apart in a plan view. This makes it possible to suppress the occurrence of abnormal discharge in the flow paths (that is, the first flow path and the second flow path).

[0049] Furthermore, the ceramic substrate according to the embodiment may have a plurality of first flow paths. The plurality of first flow paths may be positioned to surround the second flow path in a plan view. This makes it possible to suppress the occurrence of abnormal discharge in each first flow path due to an increase in the gas pressure of the heat transfer gas.

[0050] Furthermore, the embedding member according to the embodiment may have a plurality of second flow paths. The plurality of second flow paths may be positioned to surround the first flow path in a planar perspective view. This makes it possible to suppress the occurrence of abnormal discharge in each second flow path due to an increase in the gas pressure of the heat transfer gas.

[0051] Furthermore, the embedding member according to the embodiment may have a tubular portion (e.g., cylindrical portion 135) and a pillar portion (e.g., columnar portion 136) located inside the tubular portion, and the second flow path may be formed between the inner circumferential surface of the tubular portion and the outer circumferential surface of the pillar portion. This can reduce performance degradation due to heat cycles.

[0052] Furthermore, the second flow path according to the embodiment may be formed in a ring shape surrounding the pillar portion in a plan view perspective, which can reduce performance degradation due to heat cycles in the long term.

[0053] Furthermore, the cylindrical portion according to the embodiment may have a first constant diameter portion having the same diameter as the outer circumferential surface and a first different diameter portion having a different diameter, and the second flow path may be formed between the first different diameter portion and the outer circumferential surface, thereby making it possible to suppress abnormal discharge in the second flow path.

[0054] Furthermore, the pillar portion according to the embodiment may have a second constant diameter portion having the same diameter as the inner circumferential surface and a second different diameter portion having a different diameter, and the second flow path may be formed between the inner circumferential surface and the second different diameter portion, thereby reducing performance degradation due to heat cycles.

[0055] 6 and 7, the first flow path and the second flow path according to the embodiment may be arranged such that the first flow path is located on one side and the second flow path is located on the other side of an imaginary line including the center of the embedded member when viewed from above. The two-dot chain line shown in Fig. 7 is an imaginary line including the center of the embedded member when viewed from above. This makes it difficult for charged particles to reach the second flow path, reducing the occurrence of abnormal discharge in the second flow path.

[0056] Further advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0057] 100 Electrostatic Chuck 110 Ceramic substrate 110a 1st page 110b 2nd side 112 First Channel 120 base plate 122 Through hole 130 Embedded parts 131 Porous Materials 132 Second Channel 135 Cylindrical part 135a,136a Groove 136 Cylinder

Claims

1. a ceramic substrate having a first surface on which an object to be processed is placed, a second surface opposite to the first surface, and a plurality of first flow paths penetrating the first surface and the second surface; a base plate joined to the second surface of the ceramic substrate and having through holes at positions corresponding to at least the plurality of first flow paths; an embedded member located within the through-hole, the embedded member having a porous body facing the plurality of first flow paths and a second flow path communicating with the first flow paths via the porous body; and The electrostatic chuck, wherein the plurality of first flow paths are positioned apart from the second flow paths and surrounding the second flow paths in a plan view.

2. The electrostatic chuck according to claim 1 , wherein the plurality of first flow paths are positioned at equal intervals on concentric circles centered on a central axis of the second flow path.

3. 3. The electrostatic chuck according to claim 1, wherein the plurality of first flow paths are symmetrically positioned with respect to an imaginary line connecting the center of the ceramic substrate and a central axis of the second flow path.

4. a ceramic substrate having a first surface on which an object to be processed is placed, a second surface opposite to the first surface, and a first flow path penetrating the first surface and the second surface; a base plate joined to the second surface of the ceramic substrate and having a through hole at least at a position corresponding to the first flow path; an embedded member located within the through-hole, the embedded member having a porous body facing the first flow path and a second flow path communicating with the first flow path via the porous body; and the second flow path is the only flow path in the embedded member excluding the porous body, The first flow path and the second flow path are positioned apart from each other in a plan view, The electrostatic chuck has a plurality of second flow paths.

5. An electrostatic chuck as described in claim 4, wherein the ceramic substrate has a recess on the second surface, and the embedded member including the porous body is located within the recess.

6. a ceramic substrate having a first surface on which an object to be processed is placed, a second surface opposite to the first surface, and a first flow path penetrating the first surface and the second surface; a base plate joined to the second surface of the ceramic substrate and having a through hole at least at a position corresponding to the first flow path; an embedded member located within the through-hole, the embedded member having a porous body facing the first flow path and a second flow path communicating with the first flow path via the porous body; and The first flow path and the second flow path are positioned apart from each other in a plan view, The embedding member is a cylindrical portion and a pillar portion located within the cylindrical portion; the second flow path is between the inner peripheral surface of the cylindrical portion and the outer peripheral surface of the columnar portion.

7. The electrostatic chuck according to claim 6 , wherein the second flow path is formed in a ring shape surrounding the column portion in a plan view perspective.

8. the cylindrical portion has a first constant diameter portion having the same diameter as the outer circumferential surface and a first different diameter portion having a different diameter, 8. The electrostatic chuck according to claim 6, wherein the second flow path is between the first different diameter portion and the outer circumferential surface.

9. the pillar portion has a second constant diameter portion having the same diameter as the inner circumferential surface and a second different diameter portion having a different diameter, 8. The electrostatic chuck according to claim 6, wherein the second flow path is between the inner circumferential surface and the second different diameter portion.

10. 3. The electrostatic chuck according to claim 1, wherein two of the plurality of first flow paths overlap with an imaginary line connecting a center of the ceramic substrate and a central axis of the second flow path.

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