electrostatic chuck

Abstract

The objective of this invention is to provide an electrostatic chuck that can suppress the influence of refrigerant flow channel positional displacement. The solution of this invention is to provide an electrostatic chuck characterized by comprising: a ceramic dielectric substrate; a base plate supporting the ceramic dielectric substrate, having a top surface on the ceramic dielectric substrate side and a bottom surface opposite to the top surface; the base plate including a connecting channel disposed between the top and bottom surfaces through which refrigerant can pass; the connecting channel including a first flow channel portion having a pair of side surfaces along a first direction, the first direction being along the flow of the refrigerant; one of the side surfaces, when viewed along the stacking direction of the base plate and the ceramic dielectric substrate, having: a plurality of protrusions convex in a second direction perpendicular to the first direction and convex in a direction from the other side surface of the pair of side surfaces toward the side surface of one side surface; and a plurality of concave protrusions convex in a direction opposite to the second direction; the plurality of protrusions and the plurality of concave protrusions being alternately arranged.

Description

electrostatic chuck The present invention is generally related to an electrostatic chuck. Electrostatic chucks are known for holding semiconductor wafers or glass substrates as objects to be processed. Electrostatic chucks are used as a means of adsorbing and holding objects to be processed in the plasma processing chamber of semiconductor manufacturing apparatuses where processes such as etching, CVD (Chemical Vapor Deposition), sputtering, ion implantation, or ashing are performed. Electrostatic chucks apply electrostatic attraction power to, for example, built-in electrodes, and adsorb substrates such as silicon wafers through electrostatic force. An electrostatic chuck has: a ceramic dielectric substrate with a mounting surface for placing the object to be processed; and a base plate supporting the ceramic dielectric substrate. The base plate is often equipped with cooling medium channels for cooling the object to be processed. [Patent Document 1] Japanese Patent Application Publication No. 2016-115933 [Patent Document 2] Japanese Patent Application Publication No. 2020-161597 [Patent Document 3] Japanese Patent Application Publication No. 2017-208565 In the manufacturing process of electrostatic chucks, there are instances where the position of the refrigerant flow channel deviates from the design. For example, there may be individual differences in the position of the refrigerant flow channel relative to at least a portion of the substrate on which the object to be processed is placed. This misalignment of the refrigerant flow channel may result in an undesirable situation where the temperature distribution on the mounting surface deviates from the design. This invention is based on the understanding of such a problem, and its purpose is to provide an electrostatic chuck that can suppress the influence of refrigerant flow channel position displacement. The first invention is an electrostatic chuck, characterized in that it comprises: a ceramic dielectric substrate having a mounting surface for placing an object to be processed; a base plate supporting the ceramic dielectric substrate, having a top surface on the side of the ceramic dielectric substrate and a bottom surface on the opposite side of the top surface, the base plate including a connecting channel disposed between the top surface and the bottom surface through which a refrigerant can pass, the connecting channel including a first flow channel portion having a pair of sides along a first direction, the first direction being along the flow of the refrigerant, one of the pairs of sides having, when viewed along the stacking direction of the base plate and the ceramic dielectric substrate, a plurality of protrusions protruding perpendicular to the first direction and convex in a second direction from the other side of the pair of sides toward the side of the first side, and a plurality of concave protrusions protruding in a direction opposite to the second direction, the plurality of protrusions and the plurality of concave protrusions being alternately arranged. According to this electrostatic chuck, a plurality of protrusions and a plurality of recesses are alternately arranged on at least one side of the interconnecting channel. Therefore, when the position of the interconnecting channel deviates from the design, the deviation of the temperature distribution on the mounting surface of the ceramic dielectric substrate from the design can be suppressed to a smaller extent. The second invention is an electrostatic chuck, characterized in that: in the first invention, when viewed along the aforementioned stacking direction, the aforementioned other side of the aforementioned pair of side surfaces has: a plurality of convex portions protruding in a forward second direction, and a plurality of convex portions protruding in a direction opposite to the aforementioned second direction, wherein the aforementioned plurality of convex portions of the aforementioned other side surface and the aforementioned plurality of recesses of the aforementioned other side surface are arranged alternately. In this electrostatic chuck, a plurality of protrusions and a plurality of recesses are alternately arranged on both sides of the connecting channel. This further suppresses deviations in temperature distribution on the mounting surface caused by positional shifts in the connecting channel. The third invention is an electrostatic chuck, characterized in that: in the first invention or the second invention, the aforementioned first direction is the circumferential direction of the aforementioned base plate, the aforementioned plurality of protrusions on the aforementioned side of one party include a first protrusion, the aforementioned plurality of concave portions on the aforementioned side of one party include a first concave portion adjacent to the aforementioned first protrusion, and in the case where an imaginary circle tangent to the aforementioned first protrusion and centered on the center of the aforementioned base plate is used as the first imaginary circle, and an imaginary circle tangent to the aforementioned first concave portion and centered on the aforementioned center of the aforementioned base plate is used as the second imaginary circle, the first distance between the aforementioned first imaginary circle and the aforementioned second imaginary circle is longer than the shortest distance between the aforementioned side of one party and the aforementioned side of the other party. According to this electrostatic chuck, by extending the first distance, even if the position of the channel is slightly offset during the manufacturing of the electrostatic chuck, the temperature distribution on the mounting surface can be suppressed from deviating from the design. The fourth invention is an electrostatic chuck, characterized in that: in the third invention, the aforementioned first distance is 5 millimeters or more. According to this electrostatic chuck, by extending the first distance, even if the position of the channel is slightly offset during the manufacturing of the electrostatic chuck, the temperature distribution on the mounting surface can be suppressed from deviating from the design. The fifth invention is an electrostatic chuck, characterized in that: in any one of the first to fourth inventions, the first direction is the circumferential direction of the base plate, the plurality of protrusions on the side of one of the aforementioned parties include a first protrusion, the plurality of concave portions on the side of one of the aforementioned parties include a first concave portion adjacent to the first protrusion, and in the case where an imaginary circle tangent to the first protrusion and centered on the center of the base plate is used as a first imaginary circle, an imaginary circle tangent to the first concave portion and centered on the center of the base plate is used as a second imaginary circle, an imaginary circle whose distance from the first imaginary circle is equal to the distance from the second imaginary circle is used as a third imaginary circle, a straight line connecting the first protrusion and the center of the base plate is used as a first radial line, and a straight line connecting the first concave portion and the center of the base plate is used as a second radial line, the second distance along the circumferential direction between the intersection point of the first radial line and the third imaginary circle and the intersection point of the second radial line and the third imaginary circle is 30 mm or more and 140 mm or less. According to this electrostatic chuck, since the second distance is shorter than the specified value, the temperature distribution deviation on the mounting surface that accompanies the positional shift of the connecting channel can be further suppressed. The sixth invention is an electrostatic chuck, characterized in that: in any one of the first to fifth inventions, the aforementioned first direction is the circumferential direction of the aforementioned base plate, and the side of the aforementioned one is located on the outer periphery of the aforementioned base plate, which is closer than the side of the aforementioned other. When the first flow channel extends circumferentially along the base plate, if the position of the first flow channel deviates from the design, the impact on temperature distribution due to this positional deviation is often greater on the outer side of the first flow channel than on its inner side. In contrast, this electrostatic chuck has a plurality of protrusions and a plurality of recesses provided on its outer peripheral side. This further suppresses deviations in temperature distribution on the mounting surface on the outer side of the first flow channel from the design. The seventh invention is an electrostatic chuck, characterized in that: in the third or fourth invention, the aforementioned connecting channel includes a second flow channel portion having a pair of side surfaces arranged radially in the aforementioned base plate; one of the aforementioned pair of side surfaces of the aforementioned second flow channel portion, when viewed along the aforementioned stacking direction, has: a plurality of convex protrusions convex in the aforementioned second direction, and a plurality of convex recesses convex in the direction opposite to the aforementioned second direction; the aforementioned plurality of convex protrusions and the aforementioned plurality of recesses of the aforementioned second flow channel portion are alternately arranged; the aforementioned second flow channel... The part is located on the inner periphery of the bottom plate, which is closer to the first flow channel part than the aforementioned first flow channel part. The aforementioned plurality of protrusions of the aforementioned second flow channel part includes the second protrusion, and the aforementioned plurality of concave parts of the aforementioned second flow channel part includes the second concave part. If the imaginary circle tangent to the aforementioned second protrusion and centered on the center of the aforementioned bottom plate is taken as the fourth imaginary circle, and the imaginary circle tangent to the aforementioned second concave part and centered on the aforementioned center of the aforementioned bottom plate is taken as the fifth imaginary circle, and the distance between the aforementioned fourth imaginary circle and the aforementioned fifth imaginary circle is taken as the third distance, then the aforementioned first distance is longer than the aforementioned third distance. When the positions of the first and second flow channels extending circumferentially are deviated from the design, the impact on temperature distribution caused by the positional deviation in the first flow channel located on the outer periphery is often greater than that in the second flow channel located on the inner periphery of the base plate. In contrast, according to this electrostatic chuck, since the first distance in the first flow channel on the outer periphery is longer than the third distance in the second flow channel on the inner periphery, the deviation of the temperature distribution on the mounting surface from the design in the first flow channel on the outer periphery can be more effectively suppressed. The eighth invention is an electrostatic chuck, characterized in that: in the fifth invention, the aforementioned connecting channel includes a second flow channel portion having a pair of side surfaces arranged radially in the aforementioned base plate; one of the aforementioned pair of side surfaces of the aforementioned second flow channel portion, when viewed along the aforementioned stacking direction, has: a plurality of convex protrusions convex towards the aforementioned second direction, and a plurality of convex recesses convex towards a direction opposite to the aforementioned second direction; the aforementioned plurality of convex protrusions and the aforementioned plurality of recesses of the aforementioned second flow channel portion are alternately arranged; the aforementioned second flow channel portion is located on the inner periphery of the aforementioned base plate further than the aforementioned first flow channel portion; the aforementioned plurality of convex protrusions of the aforementioned second flow channel portion include second convex protrusions; the aforementioned plurality of recesses of the aforementioned second flow channel portion include second recesses; if... If we take an imaginary circle tangent to the second protrusion and centered at the center of the base plate as the fourth imaginary circle, an imaginary circle tangent to the second concave portion and centered at the center of the base plate as the fifth imaginary circle, an imaginary circle whose distance from the fourth imaginary circle is equal to the distance from the fifth imaginary circle as the sixth imaginary circle, a straight line connecting the second protrusion and the center of the base plate as the third radial line, and a straight line connecting the second concave portion and the center of the base plate as the fourth radial line, then the fourth distance is the distance along the circumference between the intersection of the third radial line and the sixth imaginary circle and the intersection of the fourth radial line and the sixth imaginary circle. In this case, the second distance is shorter than the fourth distance. According to this electrostatic chuck, since the second distance (e.g., the wavy period) in the first flow channel section on the outer periphery is shorter than the fourth distance (e.g., the wavy period) in the second flow channel section on the inner periphery, the temperature distribution on the mounting surface in the first flow channel section on the outer periphery can be more suppressed from deviating from the design. The ninth invention is an electrostatic chuck, characterized in that: in the first invention or the second invention, the aforementioned first direction is a straight line direction, the aforementioned plurality of protrusions on the side of the aforementioned one include a first protrusion, the aforementioned plurality of recesses on the side of the aforementioned one include a first recess adjacent to the aforementioned first protrusion, and in the case where a straight line tangent to the aforementioned first protrusion and extending in the aforementioned first direction is taken as a first straight line, and a straight line tangent to the aforementioned first recess and extending in the aforementioned first direction is taken as a second straight line, the fifth distance between the aforementioned first straight line and the aforementioned second straight line is longer than the shortest distance between the side of the aforementioned one and the side of the aforementioned other. According to this electrostatic chuck, by extending the fifth distance (e.g., the amount of bend on the side of the connecting channel), even if the position offset of the connecting channel is slightly increased during the manufacturing of the electrostatic chuck, the temperature distribution on the mounting surface can be suppressed from deviating from the design. The tenth invention is an electrostatic chuck, characterized in that: in the ninth invention, the aforementioned fifth distance is 5 millimeters or more. According to this electrostatic chuck, by extending the fifth distance (e.g., the amount of bend on the side of the connecting channel), even if the position offset of the connecting channel is slightly increased during the manufacturing of the electrostatic chuck, the temperature distribution on the mounting surface can be suppressed from deviating from the design. The eleventh invention is an electrostatic chuck, characterized in that: in the first invention or the second invention, the aforementioned first direction is a direction along a straight line, the aforementioned plurality of protrusions on the side of the aforementioned party include a first protrusion, the aforementioned plurality of recesses on the side of the aforementioned party include a first recess adjacent to the aforementioned first protrusion, in the case where a straight line tangent to the aforementioned first protrusion and extending in the aforementioned first direction is taken as a first straight line, a straight line tangent to the aforementioned first recess and extending in the aforementioned first direction is taken as a second straight line, a straight line at a distance equal to the distance from the aforementioned first straight line and the distance from the aforementioned second straight line is taken as a third straight line, a straight line passing through the aforementioned first protrusion and perpendicular to the aforementioned first straight line is taken as a first vertical line, and a straight line passing through the aforementioned first recess and perpendicular to the aforementioned second straight line is taken as a second vertical line, the sixth distance between the intersection point of the aforementioned first vertical line and the aforementioned third straight line and the intersection point of the aforementioned second vertical line and the aforementioned third straight line is 30 mm or more and 140 mm or less. According to this electrostatic chuck, because the sixth distance (e.g., the undulating period of the side of the connecting channel) is short, the temperature distribution deviation on the mounting surface that accompanies the positional displacement of the connecting channel can be better suppressed. The twelfth invention is an electrostatic chuck, characterized in that: in any one of the first to eleventh inventions, it further includes: a heater portion disposed inside the aforementioned ceramic dielectric substrate, or disposed between the aforementioned ceramic dielectric substrate and the aforementioned base plate, for heating the aforementioned ceramic dielectric substrate, the aforementioned heater portion including a heater line, the aforementioned heater line having a pair of sides extending along the extension direction of the aforementioned heater line, at least a portion of one of the aforementioned pair of sides overlapping the aforementioned first flow channel portion in the aforementioned lamination direction. If the position of the connecting channel that cools the mounting surface deviates from the design of the heater section that heats the mounting surface, the temperature distribution deviation on the mounting surface is likely to increase. In contrast, according to this electrostatic chuck, since at least a portion of one side of the heater overlaps with the first flow channel of the connecting channel, the temperature distribution deviation on the mounting surface can be more suppressed when the position of the connecting channel deviates from the design of the heater section. The thirteenth invention is an electrostatic chuck, characterized in that: in the twelfth invention, the aforementioned extension direction is the same as the aforementioned first direction. According to this electrostatic chuck, a plurality of recesses and a plurality of protrusions in the first flow channel are alternately arranged along the extension direction of the heater line. Accordingly, even when the position of the connecting channel deviates from the design of the heater section, deviations in temperature distribution on the mounting surface from the design can be further suppressed. According to the present invention, an electrostatic chuck can be provided that can suppress the effects of refrigerant channel positional displacement. The embodiments of the present invention will now be described with reference to the accompanying drawings. Furthermore, in each drawing, the same reference numerals are used for the same elements, and detailed descriptions are omitted as appropriate. Figure 1 is a perspective view schematically showing the electrostatic chuck in relation to the embodiment. Figures 2(a) and 2(b) are cross-sectional views schematically showing a portion of the electrostatic chuck in relation to the embodiment. For ease of explanation, a cross-sectional view is shown in Figure 1 of a portion of the electrostatic chuck. Figure 2(a) is a cross-sectional view taken along line A1-A1 as shown in Figure 1. Figure 2(b) is an enlarged view of region B1 shown in Figure 2(a). Furthermore, the object to be processed, W, is omitted in Figure 2(b). As shown in Figures 1, 2(a) and 2(b), the electrostatic chuck 10 according to the embodiment includes a ceramic dielectric substrate 100, a heater section 200 and a base plate 300. The ceramic dielectric substrate 100 is, for example, a flat substrate made of polycrystalline ceramics sintered compact, and has a first principal surface 101 on which a processing object W, such as a semiconductor wafer, is placed, and a second principal surface 102 on the opposite side of the first principal surface 101. In this specification, the direction perpendicular to the first main surface 101 is defined as the Z direction. In other words, the Z direction is the direction connecting the first main surface 101 and the second main surface 102. The Z direction is also the direction from the base plate 300 toward the ceramic dielectric substrate 100. Furthermore, one of the directions orthogonal to the Z direction is defined as the X direction, and the direction orthogonal to both the Z and X directions is defined as the Y direction. In this specification, "[in-plane]" refers to, for example, within the XY plane. Furthermore, in this specification, "[planar view]" refers to the view along the Z direction. Examples of crystalline materials included in the ceramic dielectric substrate 100 include Al. 2O 3. AlN, SiC, Y2O3, and YAG, etc. The use of these materials can improve the infrared transmittance, thermal conductivity, insulation resistance, and plasma durability of the ceramic dielectric substrate 100. An electrode layer 111 is disposed inside the ceramic dielectric substrate 100. The electrode layer 111 is disposed between the first main surface 101 and the second main surface 102. That is, the electrode layer 111 is formed by inserting into the ceramic dielectric substrate 100. The electrode layer 111 is integrally sintered into the ceramic dielectric substrate 100. Furthermore, the electrode layer 111 is not limited to being disposed between the first main surface 101 and the second main surface 102, but may also be attached to the second main surface 102. The electrostatic chuck 10 generates a charge on the first main surface 101 side of the electrode layer 111 by applying an adsorption and holding voltage to the electrode layer 111, and holds the object W to be processed by electrostatic adsorption. Electrode layers 111 are disposed along the first main surface 101 and the second main surface 102. Electrode layers 111 are adsorption electrodes used to adsorb and hold the object W to be treated. Electrode layers 111 can be unipolar or bipolar. Furthermore, electrode layers 111 can also be tripolar or other multipolar types. The number or arrangement of electrode layers 111 can be suitably selected. A base plate 300 is disposed on the second main surface 102 side of the ceramic dielectric substrate 100, supporting the ceramic dielectric substrate 100. As shown in FIG2(a), the base plate 300 has a top surface 302 on the side of the ceramic dielectric substrate 100 and a bottom surface 303 on the opposite side of the top surface 302. The base plate 300 includes a connecting channel 301 disposed between the top surface 302 and the bottom surface 303. That is, the connecting channel 301 is disposed inside the base plate 300. Examples of materials for the base plate 300 include aluminum, aluminum alloy, titanium, and titanium alloy. The base plate 300 functions to regulate the temperature of the ceramic dielectric substrate 100. For example, when cooling the ceramic dielectric substrate 100, a cooling medium flows into the connecting channel 301, passes through the connecting channel 301, and then flows out through the connecting channel 301. Accordingly, the cooling medium absorbs heat from the base plate 300, thereby cooling the ceramic dielectric substrate 100 mounted thereon. In other words, the connecting channel 301 functions as a cooling medium flow channel through which the cooling medium can pass. As shown in Figure 2(a), in this example, the base plate 300 includes an upper member 300a and a lower member 300b. The upper member 300a is disposed on the lower member 300b. The top surface 300bf of the lower member 300b is planar. A groove 300g (recess) forming a connecting channel 301 is provided on the bottom surface 300af of the upper member 300a. The bottom surface 300af of the upper member 300a and the top surface 300bf of the lower member 300b interlock to form the connecting channel 301. That is, a portion of the top surface 300bf of the lower member 300b becomes the bottom surface 301b (bottom surface) of the connecting channel 301. The inner surface of the groove 300g of the upper member 300a becomes the top surface 301u and the side surface 301s of the connecting channel 301. The side surface 301s is a surface that intersects the XY plane. Furthermore, protrusions 113 are provided as needed on the first main surface 101 side of the ceramic dielectric substrate 100. Grooves 115 are provided between adjacent protrusions 113. The grooves 115 are interconnected. A space is formed between the back side of the object W to be processed, which is mounted on the electrostatic chuck 10, and the grooves 115. The trench 115 is connected to the inlet channel 321, which is a through-base plate 300 and a ceramic dielectric substrate 100. If a transfer gas such as helium (He) is introduced through the inlet channel 321 while the object to be processed W is being held in place, the transfer gas flows into the space between the object to be processed W and the trench 115, and the object to be processed W can be directly heated or cooled by the transfer gas. The heater section 200 heats the ceramic dielectric substrate 100. By heating the ceramic dielectric substrate 100, the heater section 200 heats the workpiece W through the ceramic dielectric substrate 100. In this example, the heater section 200 is disposed between the first main surface 101 and the second main surface 102. That is, the heater section 200 is disposed inside the ceramic dielectric substrate 100. The heater section 200 is formed by being inserted into the ceramic dielectric substrate 100. In other words, the heater section 200 is built into the ceramic dielectric substrate 100. Figures 3(a) and 3(b) are schematic cross-sectional views showing a portion of the electrostatic chuck in relation to a modified example of the embodiment. Figure 3(b) is an enlarged view of region B1 shown in Figure 3(a). Furthermore, the object being processed, W, is omitted in Figure 3(b). As shown in Figures 3(a) and 3(b), the heater section 200 may not be integral with the ceramic dielectric substrate 100. The heater section 200 is disposed between the ceramic dielectric substrate 100 and the base plate 300. An adhesive layer 403 is provided between the base plate 300 and the heater section 200. An adhesive layer 403 is provided between the heater section 200 and the ceramic dielectric substrate 100. Examples of materials for the adhesive layer 403 include heat-resistant resins such as polysiloxane, which have high thermal conductivity. Figure 4 is a schematic cross-sectional view showing a portion of the electrostatic chuck in relation to an embodiment. Figure 4 corresponds to the cross-section taken along line A2-A2 shown in Figure 2, showing the planar shape of the base plate 300 and connecting channel 301 from above. The planar shape of the base plate 300 is, for example, circular. Furthermore, this circle is not only a perfect circle but also includes slightly circular shapes. One end 301c of the connecting channel 301 is located near the center 300c of the planar shape of the base plate 300. The other end 301d of the connecting channel 301 is located on the outer periphery of the planar shape of the base plate 300. When viewed along the lamination direction, the connecting channel 301 is a vortex connecting one end 301c and the other end 301d. For example, refrigerant R flows into the connecting channel 301 from one end 301c, flows through the vortex-shaped connecting channel 301, and flows out from the other end 301d to the outside of the connecting channel 301. Conversely, refrigerant R may also flow into the connecting channel 301 from the other end 301d, flow through the connecting channel 301, and flow out from one end 301c to the outside of the connecting channel 301. In one embodiment, at least a portion of the connecting channel 301 is meandering. For example, the connecting channel 301 includes a first flow channel portion 311 extending along a first direction D1. The first direction D1 is perpendicular to the lamination direction (i.e., the Z direction) of the base plate 300 and the ceramic dielectric substrate 100. In this example, the first direction D1 is the circumferential direction of the planar shape of the base plate 300 (the direction on the circumference centered at the center 300c). The first direction D1 is, for example, along the direction of refrigerant flow. For example, the direction of refrigerant flow within the connecting channel 301 (the path of refrigerant flow) is along the first direction D1. In this example, the first flow channel portion 311 is disposed in a region further outward than the central region CR of the base plate 300. The central region CR is, for example, a range within a defined radius centered on the center 300c in planar view. The defined radius is, for example, half the radius of the base plate 300. The first flow channel portion 311 is the outermost portion of the spiral-shaped connecting channel 301. However, the first flow channel portion 311 may also be disposed in the central region CR. The first flow channel portion 311 is arranged to surround the center 300c. For example, the first flow channel portion 311 surrounds the center 300c in one ring and encloses the entire circumference of the center 300c. The first flow channel portion 311 may be arc-shaped (part of a spiral or ring shape) and may surround the center 300c more than one ring (for example, about 2 to 4 rings or more). The outer periphery (end (outer edge) on the XY plane) of the connecting channel 301 may overlap with the outer periphery of the object to be processed W placed on the ceramic dielectric substrate 100 in the Z direction. In plan view, the outer periphery of the connecting channel 301 may be the inner or outer side of the outer periphery of the object to be processed W placed on the ceramic dielectric substrate 100. The first flow channel portion 311 has a pair of side surfaces (inner wall surfaces) intersecting the XY plane. The pair of side surfaces extend, for example, along a first direction D1. For example, each side of the pair of side surfaces meanders along the first direction D1. Specifically, the first flow channel portion 311 has a first side surface 31 and a second side surface 32. The first side surface 31 and the second side surface 32 are part of the side surface 301s of the connecting channel 301. Furthermore, the extent of the flow channel portion (first flow channel portion 311, second flow channel portion 312, etc., described later) or side portion (first side portion 31, second side portion 32, third side portion 33, fourth side portion 34, etc., described later) along the first direction D1 includes the case where the flow channel portion or side portion extends along the first direction D1 while meandering. When the first direction D1 is the circumference of the base plate 300, the shape in which the flow channel portion or side portion extends gradually away from (or near) the center 300c of the base plate 300 while circumferentially surrounding the center 300c of the base plate 300 is also included in the extent of the flow channel portion or side portion along the first direction D1. For example, when the flow channel portion is a vortex-shaped part centered on the center 300c of the base plate 300, the flow channel portion or side portion extends along the circumference of the base plate 300. The following description pertains to the case where the first side 31 is the outer side of the base plate 300, and the second side 32 is the inner side of the base plate 300. That is, the second side 32 is located between the first side 31 and the center 300c of the base plate 300. However, it is also possible for the first side 31 to be the inner side of the base plate 300, and the second side 32 to be the outer side of the base plate. The first side 31 and the second side 32 face each other and extend in the XY plane. Refrigerant flows between the first side 31 and the second side 32. For example, the first side 31 faces the second side 32 radially in the planar shape of the base plate 300. At least one of a pair of sides of the connecting channel 301 is meandering. That is, one of the pair of sides (first side 31 and second side 32) of the connecting channel 301, when viewed along the Z direction, has a plurality of protrusions and a plurality of recesses. For example, the first side 31 has a plurality of protrusions 31p and a plurality of recesses 31q. Each of the plurality of protrusions 31p is convex in the second direction D2. Each of the plurality of recesses 31q is convex in the direction D3 opposite to the second direction D2. The second direction D2 is a direction in the XY plane perpendicular to the first direction D1. The second direction D2 is a direction from one of the pair of sides of the connecting channel 301 (second side 32) toward one of them (first side 31). In this example, the second direction is the radial direction of the planar shape of the base plate 300, and is the direction from the center 300c of the base plate 300 toward the outer periphery of the base plate 300. That is, for example, in a plan view, the convex portion 31p is a convex shape that protrudes outward from the base plate 300 (for example, a convex shape that protrudes in the direction from the center of the base plate 300 toward the outer edge). For example, in a plan view, the concave portion 31q is a convex shape that protrudes inward from the base plate 300 (for example, a convex shape that protrudes in the direction from the outer edge of the base plate 300 toward the center). A plurality of protrusions 31p and a plurality of recesses 31q are alternately arranged along the path of the refrigerant flow within the connecting channel 301. The plurality of protrusions 31p and the plurality of recesses 31q are alternately arranged along a first direction D1. For example, the plurality of protrusions 31p are arranged along the first direction D1, and the plurality of recesses 31q are arranged along the first direction D1. One recess 31q connects to the two protrusions 31p that are closest to each other in the first direction D1. Furthermore, one protrusion 31p connects to the two recesses 31q that are closest to each other in the first direction D1. In this example, the two sides of a pair of sidewalls of channel 301 are meandering. That is, when viewed along the Z direction, the other side of the pair of sidewalls (first sidewall 31 and second sidewall 32) of channel 301 has a plurality of protrusions and a plurality of concave portions. That is, the second sidewall 32 has a plurality of protrusions 32p and a plurality of concave portions 32q. Each of the plurality of protrusions 32p is convex in the second direction D2. Each of the plurality of concave portions 32q is convex in the direction D3 opposite to the second direction D2. That is, for example, in plan view, the protrusions 32p are convex in the direction of the outer side of the base plate 300 (for example, convex in the direction from the center of the base plate 300 toward the outer edge). For example, in plan view, the concave portions 32q are convex in the direction of the inner side of the base plate 300 (for example, convex in the direction from the outer edge of the base plate 300 toward the center). A plurality of protrusions 32p and a plurality of recesses 32q are alternately arranged along the path of the refrigerant flow within the connecting channel 301. The plurality of protrusions 32p and the plurality of recesses 32q are alternately arranged along the first direction D1. In a planar view, the convex portion 31p, concave portion 31q, convex portion 32p, and concave portion 32q are curves (e.g., arcs). However, it is also possible that the convex portion 31p, concave portion 31q, convex portion 32p, and concave portion 32q each include at least a straight portion. It is also possible that a portion extending along the first direction D1 is disposed between the convex portion 31p and the concave portion 31q. It is also possible that a portion extending along the first direction D1 is disposed between the convex portion 32p and the concave portion 32q. For example, a plurality of protrusions 31p include protrusions 31pb and 31pc. Protrusion 31pc is located inside the base plate 300, closer to the protrusion 31pb. For example, protrusions 31pc and 31pb are arranged in the second direction D2. However, protrusions 31pc and 31pb may not be arranged in the second direction D2. For example, a plurality of recesses 31q include recesses 31qb and 31qc. Recess 31qc is located inside the base plate 300, closer to the recess 31qb. For example, recesses 31qc and 31qb are arranged in the second direction D2. However, recesses 31qc and 31qb may not be arranged in the second direction D2. Figure 5 is a schematic cross-sectional view showing a portion of the electrostatic chuck in relation to an embodiment. Figure 5 is an enlarged view of a portion of Figure 4. Each protrusion 31p has a top 31pt (e.g., a vertex). The top 31pt, when viewed from a position in direction D3 away from the protrusion 31p (e.g., the center 300c of the base plate 300), is the portion that protrudes most prominently in the second direction D2. For example, the top 31pt is the outermost portion of the protrusion 31p located on the base plate 300. For example, in the top 31pt, the distance between the first side 31 and the center 300c becomes extremely large. For example, in the top 31pt, the distance between the first side 31 and the outer periphery 300e of the base plate 300 becomes extremely small. Each recess 31q has a top 31qt (e.g., a vertex). The top 31qt, within a recess 31q, is the portion most recessed in direction D3 when viewed from a position away from the recess 31q in direction D3 (e.g., the center 300c of the base plate 300). For example, in the top 31qt, the distance between the first side surface 31 and the center 300c is minimal. For example, the top 31qt is the innermost portion of the base plate 300 within the recess 31q. For example, in the top 31qt, the distance between the first side surface 31 and the outer perimeter 300e of the base plate 300 is maximum. Each protrusion 32p has a top 32pt (e.g., a vertex). The top 32pt, when viewed from a position in direction D3 away from the protrusion 32p (e.g., the center 300c of the base plate 300), is the portion that protrudes most significantly beyond the second direction D2. For example, the top 32pt is the outermost portion of the protrusion 32p located on the base plate 300. For example, in the top 32pt, the distance between the second side 32 and the center 300c becomes maximum. For example, in the top 32pt, the distance between the second side 32 and the outer perimeter 300e of the base plate 300 becomes minimum. Each recess 32q has a top 32qt (e.g., a vertex). The top 32qt, within a recess 32q, is the portion most recessed in direction D3 when viewed from a position away from the recess 32q in direction D3 (e.g., the center 300c of the base plate 300). For example, the top 32qt is the innermost portion of the recess 32q located on the base plate 300. For example, in the top 32qt, the distance between the second side surface 32 and the center 300c becomes minimal. For example, in the top 32qt, the distance between the second side surface 32 and the outer perimeter 300e of the base plate 300 becomes maximum. The aforementioned tops can also be edges or faces, rather than vertices. As shown in Figure 5, the first flow channel 311 includes: a first portion 311a formed by a top 31pt; and a second portion 311b formed by a top 31qt. In plan view, the first portion 311a is the area between the top 31pt and the position on the second side 32 closest to the top 31pt. That is, each of the first portions 311a, in plan view, is the area between each of the top 31pt and the position on the second side 32 closest to each of the top 31pt. Similarly, in plan view, the second portion 311b is the area between the top 31qt and the position on the second side 32 closest to the top 31qt. In other words, each of the second portions 311b, in plan view, is the area between each of the top 31qt and the position on the second side 32 closest to each of the top 31qt. The first portions 311a and the second portions 311b are arranged alternately along the path of the refrigerant. For example, within the first flow channel 311, in the range between the first portions 311a that are closest to each other along the path of the refrigerant, the direction D31p (see Figure 4) connecting the tops 31pt at both ends of the range is along a first direction D1 at a point within that range. Similarly, within the range between the second portions 311b that are closest to each other along the path of the refrigerant in the first flow channel 311, the direction D31q (see Figure 4) connecting the tops 31qt at both ends of the range is along a first direction D1 at a point within that range. Furthermore, for example, the direction DR1 (hereinafter referred to as [first refrigerant direction DR1]) in which the refrigerant flows through the first flow channel 311 is along the first direction D1. In this example, because the connecting channel 301 is curved and the first side 31 and the second side 32 are meandering, the first refrigerant direction DR1 along the path of the refrigerant may also change. In this case, for example, the first refrigerant direction DR1 at any point in the first flow channel 311 is along the first direction D1 at that point (in this example, the circumferential direction at that point). For example, as shown in Figure 5, in the first flow channel section 311, in the range between the first part 311a and the second part 311b that are adjacent to each other along the path of the refrigerant, the first refrigerant direction DR1 can be regarded as the direction connecting the center of the first part 311a located at one end of the range and the center of the second part 311b located at the other end of the range. Furthermore, "two directions [along]" refers not only to the case where the two directions are parallel, but also to the case where the angle between the two directions (the smaller angle between the two directions) is less than 50° or less than 25°. For example, as shown in Figure 5, at any point in the first flow channel 311, the angle θ between the first direction D1 (circumferential) and the first refrigerant direction DR1 is less than 50° or less than 25°. Furthermore, the direction Dα shown in FIG5 can also be used as the first refrigerant direction DR1 at any point α within the connecting channel 301. In plan view, direction Dα is the direction perpendicular to the line segment L connecting the shortest side 31 and the second side 32. The line segment L passes through this arbitrary point α. Alternatively, within the first flow channel 311, in the range between adjacent first portions 311a along the refrigerant path, the direction D31p (refer to FIG4) connecting the tops 31pt at both ends of this range can also be used as the first refrigerant direction DR1. Alternatively, within the first flow channel 311, in the range between adjacent second portions 311b along the refrigerant path, the direction D31q (refer to FIG4) connecting the tops 31qt at both ends of this range can also be used as the first refrigerant direction DR1. In this example, the width of the first flow channel portion 311 is constant. For example, the convex portion 31p (top 31pt) and the convex portion 32p (top 32pt) are arranged in the second direction D2. For example, the concave portion 31q (top 31qt) and the concave portion 32q (top 32qt) are arranged in the second direction D2. However, in an embodiment, the width of the first flow channel portion 311 is not constant, and may vary along the path of the refrigerant. The convex portion 31p (top 31pt) may not be arranged with the convex portion 32p (top 32pt) in the second direction D2, but may be arranged with the concave portion 32q (top 32qt) in the second direction D2. The concave portion 31q (top 31qt) may not be arranged with the concave portion 32q (top 32qt) in the second direction D2, but may be arranged with the convex portion 32p (top 32pt) in the second direction D2. Figure 6 is a schematic cross-sectional view showing a portion of the electrostatic chuck in relation to an embodiment. Figure 6 is an enlarged view of a portion of Figure 4. The plurality of protrusions 31p includes a first protrusion 31pa. The plurality of recesses 31q includes a first recess 31qa. The first recess 31qa is adjacent to and continues the first protrusion 31pa. That is, the first recess 31qa and the first protrusion 31pa are arranged in the first direction D1, and the first recess 31qa is the one closest to the first protrusion 31pa among the plurality of recesses 31q. The distance L1 (first distance) shown in Figure 6 is longer than the distance La. The distance La is the shortest distance between one side (first side 31) and the other side (second side 32) of the first flow channel portion 311. That is, the distance La is the width of the narrowest part of the first flow channel portion 311 in planar view. Furthermore, as mentioned above, in this example, the width of the first flow channel portion 311 is constant. The distance L1 corresponds to the distance along the second direction D2 (the second direction D2 in either the top 31pt or the top 31qt) between the top 31pt of the first protrusion 31pa and the top 31qt of the first recess 31qa. For example, the distance L1 corresponds to a multiple of the amplitude of the meandering of the first side 31. More specifically, distance L1 is the shortest distance between the first imaginary circle IC1 and the second imaginary circle IC2 shown in Figure 6. The first imaginary circle IC1 is an imaginary circle tangent to the first protrusion 31pa (the top 31pt of the first protrusion 31pa) and centered at the center 300c of the base plate 300. The second imaginary circle IC2 is an imaginary circle tangent to the first concave portion 31qa (the top 31qt of the first concave portion 31qa) and centered at the center 300c of the base plate 300. Distance L1 is, for example, 5 mm or more and 30 mm or less, preferably 10 mm or more and 15 mm or less. For example, the amplitude (half of distance L1) can also be less than or equal to distance La. Distance L1 is preferably more than 2 times and less than 3 times the distance La. For example, when distance La is 3 mm, distance L1 is preferably 6 mm or more and 9 mm or less; when distance La is 7 mm, distance L1 is preferably 14 mm or more and 21 mm or less. The distance L2 (second distance) shown in Figure 6 is, for example, 30 mm or more and 140 mm or less, preferably 50 mm or more and 80 mm or less. Distance L2 corresponds to the distance along the first direction D1 between the top 31pt of the first protrusion 31pa and the top 31qt of the first recess 31qa. For example, distance L2 corresponds to half the length of the meandering period of the first side surface 31. Distance L2 is preferably 10 times or more and 20 times greater than distance La. For example, when distance La is 3 mm, distance L2 is preferably 30 mm or more and 60 mm or less; when distance La is 7 mm, distance L2 is preferably 70 mm or more and 140 mm or less. More specifically, distance L2 is the distance between points p1 and p2 as shown in Figure 6 along the first direction D1 (circumferential direction). Point p1 is the intersection of the third imaginary circle IC3 and the first radial line R1. Point p2 is the intersection of the third imaginary circle IC3 and the second radial line R2. The third imaginary circle IC3 is an imaginary circle centered on the center 300c of the base plate 300, located between the first imaginary circle IC1 and the second imaginary circle IC2. The distance (shortest distance) between the first imaginary circle IC1 and the third imaginary circle IC3 is equal to the distance (shortest distance) between the second imaginary circle IC2 and the third imaginary circle IC3. The first radial line R1 is a straight line passing through the center 300c of the base plate 300 and the first protrusion 31pa (the top 31pt of the first protrusion 31pa). The second radial line R2 is a straight line passing through the center 300c of the base plate 300 and the first concave portion 31qa (the top 31qt of the first concave portion 31qa). Furthermore, the same description applies to the shape of the recess and protrusion disposed on the second side 32 as to the shape of the recess and protrusion disposed on the first side 31. Figures 7(a) to 7(f) are schematic cross-sectional views showing an example of a manufacturing method of an electrostatic chuck related to the embodiment. In the manufacturing process of the electrostatic chuck, there are cases where the position of the connecting channel 301 (refrigerant flow channel) disposed on the base plate 300 deviates from the design. Figures 7(a) to 7(c) show the case where the position of the connecting channel 301 does not deviate from the design. Figures 7(d) to 7(f) show an example of the case where the position of the connecting channel 301 deviates from the design. As shown in Figure 7(a), the upper member 300a is joined to the lower member 300b. Accordingly, as shown in Figure 7(b), a base plate 300 is formed. Furthermore, a ceramic dielectric substrate 100 is joined to the base plate 300. Accordingly, as shown in Figure 7(c), an electrostatic chuck 10 is manufactured. In addition, in this example, the heater section 200 is built into the ceramic dielectric substrate 100, and the electrode 111 is omitted. For example, as shown in Figure 7(d), in the joining of the upper member 300a and the lower member 300b, the relative positions of the upper member 300a and the lower member 300b deviate from the design. Accordingly, the relative positions of the mounting surface of the ceramic dielectric substrate 100 (and the object to be processed placed thereon) or the connecting channel 301 of the heater section 200 deviate from the design. For example, as shown in Figure 7(e), during the manufacturing process of the ceramic dielectric substrate 100 and the heater section 200, the relative positions of the ceramic dielectric substrate 100 and the heater section 200 deviate from the design. Accordingly, the relative position of the connecting channel 301 of the heater section 200 also deviates from the design. For example, as shown in Figure 7(f), during the bonding of the ceramic dielectric substrate 100 and the base plate 300, the relative positions of the ceramic dielectric substrate 100 and the base plate 300 deviate from the design. Consequently, the relative positions of the mounting surface of the ceramic dielectric substrate 100 (and the object to be processed placed thereon) or the connecting channel 301 of the heater section 200 deviate from the design. As explained above, the electrostatic chuck 10 has a connecting channel 301 on the base plate 300 for cooling the wafer or similar object being adsorbed. This coolant suppresses heat input from the plasma during processing, preventing overheating of the wafer. In the electrostatic chuck 10, which includes the heater section 200, the temperature of the surface on which the object to be processed is placed is controlled by heating using the heater section 200 and cooling using the coolant. Furthermore, cooling gas inlet holes or channels are provided on the ceramic dielectric substrate to control the temperature of the adsorbed object using helium or similar gases. Appropriately designing the arrangement of these cooling gas inlet holes or channels and their positional relationship with the connecting channel ensures that the temperature distribution on the surface on which the object to be processed is as uniform as possible. For example, the electrostatic chuck 10 is formed by bonding a base plate to a ceramic substrate using a bonding layer. Furthermore, there are cases where multiple components are bonded together to form the base plate. During the manufacturing process of the electrostatic chuck 10, there are instances where the position of the connecting channel 301 relative to the ceramic dielectric substrate 100 deviates from the design. This misalignment of the connecting channel 301 may result in an undesirable situation where the temperature distribution on the surface of the ceramic dielectric substrate 100 where the object to be processed is placed deviates from the design. In contrast, in the electrostatic chuck related to the embodiment, a plurality of protrusions and a plurality of recesses are alternately arranged on at least one side of the first flow channel portion 311 of the connecting channel 301. Therefore, when the position of the connecting channel deviates from the design, the deviation of the temperature distribution on the mounting surface of the ceramic dielectric substrate from the design can be suppressed to a smaller extent. Figures 8(a) to 8(d) and 9(a) to (f) are schematic diagrams showing the simulation of the temperature distribution of the electrostatic chuck. Figures 8(a) to 8(d) show the model of the electrostatic chuck used for simulation. Figures 8(a) and 8(b) are perspective views of the electrostatic chuck related to the reference example, viewed from above. In Figures 8(a) and 8(b), region Ra corresponds to the mounting surface of the ceramic dielectric substrate, and region Rb corresponds to the connecting channel (coolant channel) located below region Ra. In the electrostatic chuck related to the reference example, no protrusions or recesses are provided in region Rb (connecting channel). Figure 8(b) shows the state in which the position of region Rb relative to region Ra is offset by a distance d in the direction of the arrow from the state in Figure 8(a). Figures 8(c) and 8(d) are perspective views of the electrostatic chuck related to the embodiment, viewed from above. In Figures 8(c) and 8(d), region Ra corresponds to the mounting surface of the ceramic dielectric substrate, and region Rc corresponds to the connecting channel (coolant channel) located below region Ra. In the electrostatic chuck related to the embodiment, region Rc (connecting channel) is provided with protrusions and recesses. That is, region Rc has a plurality of portions Rc1 and a plurality of portions Rc2. For example, portions Rc1 correspond to protrusions 31p, and portions Rc2 correspond to recesses 31q. Figure 8(d) shows the state in which the position of region Rc relative to region Ra is offset by only a distance d in the direction of the arrow from the state in Figure 8(c). The offset amount (distance d) is the same in Figures 8(b) and 8(d). Figures 9(a) to 9(c) show the temperature distribution on the mounting surface of the ceramic dielectric substrate in the electrostatic chuck related to the reference example. Figure 9(a) shows the temperature distribution when the entire area is heated while cooling region Rb with a specified amount of heat in the mode shown in Figure 8(a). Figure 9(b) shows the temperature distribution when the entire area is heated while cooling region Rb with a specified amount of heat in the mode shown in Figure 8(b). Figure 9(c) shows the value of subtracting the temperature of Figure 9(a) from the temperature of Figure 9(b). In other words, Figure 9(c) shows the effect of the positional shift of region Rb on the temperature distribution. Similarly, Figures 9(d) to 9(f) show the temperature distribution on the mounting surface of the ceramic dielectric substrate in the electrostatic chuck, corresponding to the embodiments. Figure 9(d) shows the temperature distribution in the mode shown in Figure 8(c) where the entire area is heated while the region Rc is cooled with a predetermined amount of heat. Figure 9(e) shows the temperature distribution in the mode shown in Figure 8(d) where the entire area is heated while the region Rc is cooled with a predetermined amount of heat. Figure 9(f) shows the value of subtracting the temperature of Figure 9(e) from the temperature of Figure 9(d). In other words, Figure 9(f) shows the effect of the positional shift of region Rc on the temperature distribution. In the vicinity of the arrow position shown in Figure 9(c), the temperature changes by 18°C ​​due to the positional shift of region Rb. In contrast, in the vicinity of the arrow position shown in Figure 9(f), the temperature changes by 3°C due to the positional shift of region Rc. Moreover, the temperature change in Figure 9(f) is more gradual than that in Figure 9(c). By providing irregularities in the connecting channel, the temperature change of the mounting surface caused by the positional shift of the connecting channel can be reduced. That is, for example, by adding irregularities to the side of the connecting channel extending in the first direction D1, the robustness of the temperature distribution to the positional shift of the connecting channel is improved. In this example, as already described, even on one of the two sides (first side 31 and second side 32), a plurality of protrusions and a plurality of recesses are provided, arranged alternately. That is, on both sides of the connecting channel 301, a plurality of protrusions and a plurality of recesses are alternately configured. This further suppresses deviations in temperature distribution on the mounting surface accompanying positional shifts of the connecting channel 301. However, in the embodiment, it is sufficient that at least one of the pair of sides (first side 31 and second side 32) is provided with a recess and a protrusion. The first side 31 may have a protrusion and a recess, while the second side 32 may not have a protrusion and a recess and may extend in the first direction D1. For example, the side (first side 31) with a plurality of recesses and a plurality of protrusions among the pair of sides may be located further to the outer periphery of the base plate 300 than the other side (second side 32). When the first flow channel portion 311 of the connecting channel 301 extends circumferentially along the base plate 300, if the position of the first flow channel portion 311 deviates from the design, the effect on temperature distribution due to the positional deviation is often greater on the outer side of the first flow channel portion 311 than on the inner side. In contrast, a plurality of protrusions and a plurality of recesses are provided on the outer periphery side (first side 31). This further suppresses the deviation of the temperature distribution on the mounting surface from the design on the outer periphery side of the first flow channel portion 311. However, the second side 32 may have a convex part and a concave part, and the first side 31 may not have a convex part and a concave part but extend in the first direction D1. Furthermore, in this example, the first direction D1 is the circumferential direction of the base plate 300. Accordingly, for example, the first flow channel portion 311 extends along the shape of the base plate 300 or the object being processed W. Accordingly, it is easy to suppress, for example, the influence on temperature distribution caused by positional displacement on the outer peripheral side. Furthermore, as illustrated in Figure 6, the distance L1 is longer than the distance La. The distance L1 is, for example, 5 mm or more. Thus, by making the first distance L1 (e.g., the amount of bend in the side of the channel) longer, even if the positional offset of the channel is slightly increased during the manufacturing of the electrostatic chuck, the temperature distribution on the mounting surface can be suppressed from deviating from the design. Furthermore, as illustrated in Figure 6, the second distance L2 is between 30 mm and 140 mm. Because the second distance L2 (e.g., half the undulation period of the side of the connecting channel) is shorter than the specified value, the temperature distribution deviation from the design on the mounting surface accompanying the positional shift of the connecting channel can be further suppressed. Furthermore, in the description of the embodiments, the terms "amplitude" and "period" are used for convenience. However, in the embodiments, the first distance L1 covering the entire circumference may not be fixed, and the second distance L2 may not be fixed. That is to say, the concave and convex portions may not repeat at a fixed interval. Figure 10 is a perspective view schematically showing a portion of an electrostatic chuck related to an embodiment. Figure 10 shows a portion of a heater section 200 and a portion of a connecting channel 301. The heater section 200 includes a heater element 230 located above the connecting channel 301. The heater element 230 includes a strip-shaped conductive portion extending along the XY plane. For example, the heater element 230 is electrically connected to an external power source (not shown). Current is supplied from the outside to the heater element 230, flowing from one end to the other. Accordingly, the heater element 230 (heater wire) heats up. By controlling the current flowing to the heater element 230, the heat generated by the heater element 230 can be controlled, and the temperature of the mounting surface of the ceramic dielectric substrate 100 can be controlled. A plurality of heater elements 230 may be provided. The plurality of heater elements 230 may also be arranged in the XY plane. The plurality of heater elements 230 may also be laminated in the Z direction through an insulating film. By providing a plurality of heater elements 230, the temperature of the mounting surface and the object being processed can be easily controlled. For example, the uniformity of temperature distribution within the surface of the object being processed placed on the mounting surface can be improved. The materials used for the heater element 230 may include, for example, at least one of the following metals: stainless steel, titanium, chromium, nickel, copper, aluminum, Inconel (registered trademark), molybdenum, tungsten, palladium, platinum, silver, tantalum, molybdenum carbide, and tungsten carbide. The thickness (length in the Z direction) of the heater element 230 is, for example, about 0.01 mm or more and about 0.20 mm or less. In the example shown in Figure 10, heater element 230 includes a first heater element 230a and a second heater element 230b. The first heater element 230a includes first to fifth heater wires 231 to 235. The first to fifth heater wires 231 to 235 can be electrically connected to each other or insulated from each other. The second heater element 230b includes sixth to ninth heater wires 236 to 239. The sixth to ninth heater wires 236 to 239 can be electrically connected to each other or insulated from each other. For example, the first to ninth heater lines 231 to 239 are arcs extending along the first direction D1 (circumferential direction). In plan view, the first to ninth heater lines 231 to 239 are arranged in this order from the outer periphery. That is, the first heater line 231 is the outermost part among the plurality of heater elements 230. Furthermore, the shape of the heater element 230 does not necessarily have to extend circumferentially, and it does not have to be arc-shaped. Figures 11(a) and 11(b) are perspective top views schematically showing a portion of the electrostatic chuck related to the embodiment. Figures 11(a) and 11(b) correspond to the states of the heater element 230 and connecting channel 301 shown in Figure 10 as viewed from above. Figure 11(a) shows the case where the relative position of the connecting channel 301 of the heater section 200 does not deviate from the design. Figure 11(b) shows the case where the relative position of the connecting channel 301 of the heater section 200 deviates from the design. In plan view, the first heater line 231 has a first side q1 and a second side q2 extending along the extension direction of the first heater line 231 (circumferential in this example). The first side q1 and the second side q2 are arranged radially (second direction D2). The first side q1 is located outside the base plate 300, further than the second side q2. Similarly, each of the second to ninth heater lines 232 to 239 has a pair of sides (first side q1 and second side q2). As shown in Figures 11(a) and 11(b), at least one of a pair of sides of the first heater line 231 overlaps with the first flow channel portion 311 in the Z direction. For the heater portion 200 heating the mounting surface, if the position of the connecting channel 301 cooling the mounting surface deviates from the design, the temperature distribution deviation on the mounting surface tends to increase. In contrast, according to the embodiment, since at least a portion of one side of the heater line overlaps with the first flow channel portion 311 of the connecting channel 301, the temperature distribution deviation on the mounting surface can be more effectively suppressed when the position of the connecting channel 301 relative to the heater portion 200 deviates from the design. For example, the first side q1 of the first heater line 231 overlaps with the first side surface 31 in the Z direction. The second side q2 of the first heater line 231 overlaps with the second side surface 32 in the Z direction. For example, the extending direction of the first heater line 231 is the same as the first direction D1. In this case, the plurality of recesses 31q and the plurality of protrusions 31p of the first flow channel portion 311 are alternately arranged along the extending direction of the first heater line. Accordingly, when the position of the connecting channel 301 relative to the heater portion 200 deviates from the design, the deviation of the temperature distribution on the mounting surface from the design can be further suppressed. For example, the first flow channel portion 311 may overlap with a plurality of heater lines in a planar view. In the examples of Figures 11(a) and 11(b), the first flow channel portion 311 overlaps with the first heater line 231 and the second heater line 232 in the Z direction. The first flow channel portion 311 may overlap with only one heater line or with three or more heater lines in the Z direction. Figure 12 is a schematic cross-sectional view showing a portion of another electrostatic chuck related to an embodiment. Like Figure 4, Figure 12 shows a cross-section of a portion of the electrostatic chuck 11 related to the embodiment, showing the planar shape of the base plate 300 and connecting channel 301 viewed from above. The electrostatic chuck 11, for example, includes a second flow channel portion 312 extending along a first direction D1 while meandering along it. Otherwise, the same description applies to the electrostatic chuck 11 as to the electrostatic chuck 10. The second flow channel 312 is located on the inner periphery of the base plate 300, further than the first flow channel 311. For example, the second flow channel 312 is located between the first flow channel 311 and the center 300c of the base plate 300. The second flow channel 312 may also be disposed in the central region CR of the base plate 300. The second flow channel 312 is part of a spiral-shaped connecting channel 301 and is connected to the first flow channel 311. The second flow channel 312 is disposed in a manner that surrounds the center 300c. For example, the second flow channel 312 surrounds the center 300c once and covers the entire circumference of the center 300c. However, the second flow channel 312 may also be arc-shaped (part of a spiral or annular shape) and may surround the center 300c more than once. The second flow channel 312 has a pair of side surfaces (inner wall surfaces) that intersect the XY plane. The pair of side surfaces extend, for example, along the first direction D1. Specifically, the second flow channel 312 has a third side surface 33 and a fourth side surface 34. The following description will focus on the case where the third side 33 is the outer side of the base plate 300 and the fourth side 34 is the inner side of the base plate 300. That is, the fourth side 34 is located between the third side 33 and the center 300c of the base plate 300. However, in the following description, it is also possible for the third side 33 to be the inner side of the base plate 300 and the fourth side 34 to be the outer side of the base plate. The third side 33 and the fourth side 34 face each other and extend in the XY plane. Refrigerant flows between the third side 33 and the fourth side 34. For example, the third side 33 faces the fourth side 34 radially in the planar shape of the base plate 300. One of the pair of side surfaces (third side surface 33 and fourth side surface 34) of the second flow channel 312, when viewed along the Z direction, has a plurality of protrusions and a plurality of recesses. For example, the third side surface 33 has a plurality of protrusions 33p and a plurality of recesses 33q. Each of the plurality of protrusions 33p is convex in the second direction D2. Each of the plurality of recesses 33q is convex in the direction D3, which is opposite to the second direction D2. That is, for example, in plan view, the protrusions 33p are convex in the direction of the outer side of the base plate 300 (for example, convex in the direction from the center of the base plate 300 toward the outer edge). For example, in plan view, the recesses 33q are convex in the direction of the inner side of the base plate 300 (for example, convex in the direction from the outer edge of the base plate 300 toward the center). A plurality of protrusions 33p and a plurality of recesses 33q are alternately arranged along the path of refrigerant flow within the connecting channel 301. The plurality of protrusions 33p and the plurality of recesses 33q are alternately arranged along the first direction D1. In this example, the two sides of a pair of sides of the second flow channel 312 are meandering. That is, when viewed along the Z direction, the other side of the pair of sides (third side 33 and fourth side 34) of the second flow channel 312 has a plurality of protrusions and a plurality of concave portions. That is, the fourth side 34 has a plurality of protrusions 34p and a plurality of concave portions 34q. Each of the plurality of protrusions 34p is convex in the second direction D2. Each of the plurality of concave portions 34q is convex in the direction D3 opposite to the second direction D2. That is, for example, in plan view, the protrusions 34p are convex in the direction of the outer side of the base plate 300 (for example, convex in the direction from the center of the base plate 300 toward the outer edge). For example, in plan view, the concave portions 34q are convex in the direction of the inner side of the base plate 300 (for example, convex in the direction from the outer edge of the base plate 300 toward the center). A plurality of protrusions 34p and a plurality of recesses 34q are alternately arranged along the path of refrigerant flow within the connecting channel 301. The plurality of protrusions 34p and the plurality of recesses 34q are alternately arranged along a first direction D1. In a planar view, the convex portion 33p, concave portion 33q, convex portion 34p, and concave portion 34q are curves (e.g., arcs). However, the convex portion 33p, concave portion 33q, convex portion 34p, and concave portion 34q may each include a straight portion in at least a portion. A portion extending along the first direction D1 may also be disposed between the convex portion 33p and the concave portion 33q. Similarly, a portion extending along the first direction D1 may also be disposed between the convex portion 34p and the concave portion 34q. Figure 13 is a schematic cross-sectional view showing a portion of the electrostatic chuck in relation to an embodiment. Figure 13 is an enlarged view of a portion of Figure 12. Each protrusion 33p has a top 33pt (e.g., a vertex). Among a single protrusion 33p, the top 33pt is the portion that protrudes most prominently in the second direction D2 when viewed from a position away from the protrusion 33p in direction D3 (e.g., the center 300c of the base plate 300). For example, the top 33pt is the outermost portion of the protrusion 33p located on the base plate 300 (the portion furthest from the center 300c in plan view). Each recess 33q has a top 33qt (e.g., a vertex). The top 33qt, within a recess 33q, is the portion most recessed in direction D3 when viewed from a position away from the recess 33q in direction D3 (e.g., the center 300c of the base plate 300). For example, the top 33qt is the innermost portion of the recess 33q located on the base plate 300 (the portion closest to the center 300c in plan view). Each protrusion 34p has a top 34pt (e.g., a vertex). The top 34pt, in a single protrusion 34p, is the portion that protrudes most from the second direction D2 when viewed from a position away from the protrusion 34p in direction D3 (e.g., the center 300c of the base plate 300). For example, the top 34pt is the outermost portion of the protrusion 34p located on the base plate 300. Each recess 34q has a top 34qt (e.g., a vertex). The top 34qt, within a recess 34q, is the portion most recessed in direction D3 when viewed from a position away from the recess 34q in direction D3 (e.g., the center 300c of the base plate 300). For example, the top 34qt is the innermost portion of the recess 34q located on the base plate 300. The aforementioned tops can also be edges instead of vertices. As shown in Figure 13, the second flow channel 312 includes: a third portion 312a formed by a top 33pt; and a fourth portion 312b formed by a top 33qt. In plan view, the third portion 312a is the range between the top 33pt and the position of the fourth side 34 closest to the top 33pt. That is, each of the third portions 312a, in plan view, is the region between each of the vertices 33pt and the position of the fourth side 34 closest to each of the vertices 33pt. Similarly, the fourth portion 312b, in plan view, is the range between the top 33qt and the position of the fourth side 34 closest to the top 33qt. In other words, each of the fourth portions 312b, in plan view, is the region between each of the vertices 33qt and the position of the fourth side 34 closest to each of the vertices 33qt. The third portions 312a and the fourth portions 312b are arranged alternately along the path of the refrigerant. For example, in the second flow channel 312, within the range between the third portions 312a that are closest to each other along the path of the refrigerant, the direction D33p (see Figure 12) connecting the tops 33pt at both ends of this range is along the first direction D1 at a point within this range. Similarly, in the second flow channel 312, within the range between the fourth portions 312b that are closest to each other along the path of the refrigerant, the direction D33q (see Figure 12) connecting the tops 33qt at both ends of this range is along the first direction D1 at a point within this range. Furthermore, for example, the direction DR2 of the refrigerant flowing through the second flow channel 312 (hereinafter referred to as [second refrigerant direction DR2]) is along the first direction D1. In this example, because the connecting channel 301 is curved, and the third side 33 and the fourth side 34 are meandering, the second refrigerant direction DR2 changes along the path of the refrigerant. In this case, for example, the second refrigerant direction DR2 at any point in the second flow channel 312 is along the first direction D1 at that point (in this example, the circumferential direction at that point). For example, as shown in Figure 13, in the second flow channel section 312, between the third part 312a and the fourth part 312b that are adjacent to each other along the path of the refrigerant, the second refrigerant direction DR2 can be regarded as the direction connecting the center of the third part 312a and the center of the fourth part 312b. Furthermore, the direction Dβ shown in FIG13 can also be used as the second refrigerant direction DR2 at any point β within the connecting channel 301. In plan view, direction Dβ is the direction perpendicular to the line segment Lβ connecting the shortest side 33 and the fourth side 34. Line segment Lβ passes through this arbitrary point β. Alternatively, within the second flow channel 312, in the range between adjacent third portions 312a along the refrigerant path, the direction D33p (refer to FIG12) connecting the tops 33pt at both ends of this range can also be used as the second refrigerant direction DR2. Alternatively, within the second flow channel 312, in the range between adjacent fourth portions 312b along the refrigerant path, the direction D33q (refer to FIG12) connecting the tops 33qt at both ends of this range can also be used as the second refrigerant direction DR2. The width of the second flow channel portion 312 can be fixed. For example, the convex portion 33p (top 33pt) and the convex portion 34p (top 34pt) can be arranged in the second direction D2. For example, the concave portion 33q (top 33qt) and the concave portion 34q (top 34qt) can be arranged in the second direction D2. However, in an embodiment, the width of the second flow channel portion 312 is not fixed and can vary along the path of the refrigerant. The convex portion 33p (top 33pt) can be arranged in the second direction D2 with the concave portion 34q (top 34qt) instead of the convex portion 34p (top 34pt). The concave portion 33q (top 33qt) can be arranged in the second direction D2 with the convex portion 34p (top 34pt) instead of the concave portion 34q (top 34qt). Figure 14 is a schematic cross-sectional view showing a portion of the electrostatic chuck related to an embodiment. Figure 14 is an enlarged view of a portion of Figure 12. The plurality of protrusions 33p includes a second protrusion 33pa of one of the protrusions 33p. The plurality of recesses 33q includes a second recess 33qa of one of the recesses 33q. The second recess 33qa is adjacent to and continues the second protrusion 33pa. That is, the second recess 33qa and the second protrusion 33pa are arranged in the first direction D1, and the second recess 33qa is the one closest to the second protrusion 33pa among the plurality of recesses 33q. For example, as shown in Figure 14, distance L3 (the third distance) is longer than distance Lb. Distance Lb is the shortest distance between one side (the third side 33) and the other side (the fourth side 34) of the second flow channel 312. In other words, distance Lb is the width of the narrowest part of the second flow channel 312 in plan view. The distance L3 corresponds to the distance along the second direction D2 (the second direction D2 in either the top 33pt or the top 33qt) between the top 33pt and the top 33qt of the second concave portion 33pa. For example, the distance L3 corresponds to a multiple of the length of the meandering amplitude of the third side surface 33. More specifically, distance L3 is the shortest distance between the fourth imaginary circle IC4 and the fifth imaginary circle IC5 shown in Figure 14. The fourth imaginary circle IC4 is an imaginary circle tangent to the second protrusion 33pa (the top 33pt of the second protrusion 33pa) and centered at the center 300c of the base plate 300. The fifth imaginary circle IC5 is an imaginary circle tangent to the second concave portion 33qa (the top 33qt of the second concave portion 33qa) and centered at the center 300c of the base plate 300. Distance L3 is, for example, between 5 mm and 30 mm. For example, the distance L3 (third distance) of the second flow channel 312 is shorter than the distance L1 (first distance) of the first flow channel 311. When the positions of the first flow channel 311 and the second flow channel 312 extending along the circumferential direction of the connecting channel 301 deviate from the design, the effect of the positional deviation on the temperature distribution is often greater in the first flow channel 311 located on the outer periphery side of the second flow channel 312, which is located on the inner periphery side of the base plate 300. In contrast, since the first distance in the outer periphery side of the first flow channel 311 is longer than the third distance in the inner periphery side of the second flow channel, the deviation of the temperature distribution on the mounting surface from the design in the outer periphery side of the first flow channel can be more effectively suppressed. The distance L4 (fourth distance) shown in Figure 14 is, for example, 30 mm or more and 140 mm or less. The distance L2 corresponds to the distance along the first direction D1 between the top 33pt of the second protrusion 33pa and the top 33qt of the second recess 33qa. For example, the distance L4 corresponds to half the length of the meandering period of the third side 33. More specifically, distance L4 is the distance between points p3 and p4 as shown in Figure 14 along the first direction D1 (circumferential direction). Point p3 is the intersection of the sixth imaginary circle IC6 and the third radial line R3. Point p4 is the intersection of the sixth imaginary circle IC6 and the fourth radial line R4. The sixth imaginary circle IC6 is an imaginary circle centered on the center 300c of the base plate 300, located between the fourth imaginary circle IC4 and the fifth imaginary circle IC5. The distance (shortest distance) between the fourth imaginary circle IC4 and the sixth imaginary circle IC6 is equal to the distance (shortest distance) between the fifth imaginary circle IC5 and the sixth imaginary circle IC6. The third radial line R3 is a straight line passing through the center 300c of the base plate 300 and the second protrusion 33pa (the top 33pt of the second protrusion 33pa). The fourth radial line R4 is a straight line passing through the center 300c of the base plate 300 and the second concave portion 33qa (the top 33qt of the second concave portion 33qa). For example, the distance L4 (fourth distance) of the second flow channel 312 is longer than the distance L2 (second distance) of the first flow channel 311. Since the second distance (e.g., the meandering period) in the first flow channel 311 on the outer periphery is shorter than the fourth distance (e.g., the meandering period) in the second flow channel 312 on the inner periphery, the temperature distribution on the mounting surface in the first flow channel on the outer periphery can be more effectively suppressed from deviating from the design. Furthermore, the same description applies to the shape of the recess and protrusion provided on the fourth side 34 as it does to the shape of the recess and protrusion provided on the third side 33. Figures 15, 16(a), and 16(b) are perspective top views schematically showing a portion of an electrostatic chuck related to an embodiment. Figure 15 shows the heater element 230 of the electrostatic chuck 11 and the connecting channel 301. In this example, the heater element 230 includes first to seventh heater lines 231 to 237. The planar shape of each heater line is, for example, annular. Figures 16(a) and 16(b) are diagrams corresponding to a portion of the heater element 230 and the connecting channel 301 shown in Figure 15, respectively. Figure 16(a) shows the case where the relative position of the connecting channel 301 of the heater section 200 does not deviate from the design. Figure 16(b) shows the case where the relative position of the connecting channel 301 of the heater section 200 deviates from the design. As shown in Figures 16(a) and 16(b), at least one of a pair of sides of the first heater line 231 overlaps with the first flow channel portion 311 in the Z direction. Furthermore, as shown in Figure 15, for example, at least one of a pair of sides of the third heater line 233 overlaps with the second flow channel portion 312 in the Z direction. Therefore, even when the position of the connecting channel 301 relative to the heater portion 200 deviates from the design, deviations in the temperature distribution on the mounting surface from the design can be further suppressed. For example, the second flow channel 312 overlaps with the second heater line 232 and the third heater line 233 in the Z direction. The second flow channel 312 may overlap with only one heater line or with multiple heater lines. Figure 17 is a schematic cross-sectional view showing a portion of another electrostatic chuck related to the embodiment. Figure 17 shows the planar shape of the base plate 300 and connecting channel 301 of the electrostatic chuck 12 related to the embodiment, viewed from above. Unlike the electrostatic chuck 10, the planar shape of the electrostatic chuck 12 in the connecting channel 301 is not spiral-shaped, but rather, for example, serrated or serpentine. In this example, the first direction D1 is the direction on a straight line Ly parallel to the Y direction, which is either the Y direction or the direction opposite to the Y direction. The second direction D2 is the direction perpendicular to the first direction D1. In the electrostatic chuck 12, the channel 301 also includes a first flow channel portion 311. The first flow channel portion 311 includes a first side surface 31 and a second side surface 32. Each of the first flow channel portion 311, the first side surface 31, and the second side surface 32 extends along a first direction D1, for example, meandering along one side. The first side surface 31 includes a plurality of protrusions 31p and a plurality of recesses 31q. The orientation of the tops of the closest protrusions 31p among the plurality of protrusions 31p is along the first direction D1, for example, parallel to the first direction D1. The orientation of the tops of the closest recesses 31q among the plurality of recesses 31q is along the first direction D1, for example, parallel to the first direction D1. For example, a plurality of first flow channel portions 311 may be provided, arranged in the second direction D2. The connecting channel 301 may also have a flow channel portion 313 adjacent to the first flow channel portion 311 in the second direction D2. The refrigerant flows in the flow channel portion 313 in a direction opposite to the first direction D1. Furthermore, the shape of the flow channel portion 313 may be the same as the first flow channel portion 311. That is, the flow channel portion 313 may extend along the first direction D1, for example, while meandering. Each of a pair of side surfaces of the flow channel portion 313 may extend along the first direction D1, for example, while meandering. Each of the pair of side surfaces of the flow channel portion 313 includes: a plurality of convex protrusions convex towards the second direction D2, and a plurality of convex recesses convex towards the direction D3. The connecting channel 313 and the first flow channel portion 311 are connected by a bend in the connecting channel 301. Furthermore, the connecting channel 301 includes a second flow channel portion 312. The second flow channel portion 312 includes a third side surface 33 and a fourth side surface 34. Each of the second flow channel portion 312, the third side surface 33, and the fourth side surface 34 extends along a first direction D1, for example, meandering along one side. The third side surface 33 includes a plurality of protrusions 33p and a plurality of recesses 33q. The tops of the closest protrusions 33p among the plurality of protrusions 33p are oriented along the first direction D1, for example, parallel to the first direction D1. The tops of the closest recesses 33q among the plurality of recesses 33q are oriented along the first direction D1, for example, parallel to the first direction D1. For example, a plurality of second flow channel portions 312 may be provided, arranged in the second direction D2. The connecting channel 301 may also have a flow channel portion 314 adjacent to the second flow channel portion 312 in the second direction D2. The refrigerant flows in the flow channel portion 314 in a direction opposite to the first direction D1. Furthermore, the shape of the flow channel portion 314 may be the same as that of the second flow channel portion 312. That is, the flow channel portion 314 may extend along the first direction D1, for example, while meandering. Each of a pair of side surfaces of the flow channel portion 314 may extend along the first direction D1, for example, while meandering. Each of the pair of side surfaces of the flow channel portion 314 includes: a plurality of convex protrusions convex towards the second direction D2, and a plurality of convex recesses convex towards the direction D3. The flow channel portion 314 and the second flow channel portion 312 are connected by a bend in the connecting channel 301. Figure 18 is a cross-sectional view schematically showing a portion of another electrostatic chuck related to an embodiment. Figure 18 is an enlarged view of a portion of the first flow channel 311 shown in Figure 17. The plurality of protrusions 31p includes a first protrusion 31pa of protrusions 31p. The plurality of recesses 31q includes a first recess 31qa of recesses 31q. The distance L5 (fifth distance) shown in Figure 18 is, for example, longer than the distance La. The distance La is the shortest distance between one side (first side 31) of the first flow channel 311 and another side (second side 32). The distance L5 is the shortest distance between the first straight line IL1 and the second straight line IL2 shown in Figure 18. The first straight line IL1 is a straight line extending in the first direction D1, tangent to the first protrusion 31pa (the top 31pt of the first protrusion 31pa). The second straight line IL2 is a straight line extending in the first direction D1, tangent to the first concave portion 31qa (the top 31qt of the first concave portion 31qa). The distance L5 is, for example, 5 mm or more and 30 mm or less. The distance L6 (sixth distance) shown in Figure 18 is, for example, 30mm or more and 140mm or less. Distance L6 is the distance along the first direction D1 between points p5 and p6 shown in Figure 18. Point p5 is the intersection of the third line IL3 and the first vertical line V1. Point p6 is the intersection of the third line IL3 and the second vertical line V2. The third line IL3 is a line located between the first line IL1 and the second line IL2. The distance between the first line IL1 and the third line IL3 (the shortest distance) is equal to the distance between the second line IL2 and the third line IL3 (the shortest distance). The first vertical line V1 is a line passing through the first protrusion 31pa (the top 31pt of the first protrusion 31pa) and perpendicular to the first line IL1. The second vertical line V2 is a line passing through the first concave portion 31qa (the top 31qt of the first concave portion 31qa) and perpendicular to the second line IL2. By using a longer fifth distance (e.g., the amount of bend on the side of the connecting channel), even if the positional offset of the connecting channel is slightly larger during the manufacturing of the electrostatic chuck, the temperature distribution on the mounting surface that deviates from the design can be suppressed. Because the sixth distance (e.g., the bend period on the side of the connecting channel) is short, the temperature distribution on the mounting surface that deviates from the design due to the positional offset of the connecting channel can be suppressed even more. In the example of Figure 18, the convex portion 31p (top 31pt) and the convex portion 32p (top 32pt) are arranged in the second direction D2. Furthermore, the concave portion 31q (top 31qt) and the concave portion 32q (top 32qt) are arranged in the second direction D2. Accordingly, the width of the first flow channel portion 311 can be kept constant. However, it is also possible that the convex portion 31p (top 31pt) and the convex portion 32p (top 32pt) are not arranged in the second direction D2. Similarly, it is also possible that the concave portion 31q (top 31qt) and the concave portion 32q (top 32qt) are not arranged in the second direction D2. Figure 19 is a cross-sectional view schematically showing a portion of another electrostatic chuck related to an embodiment. Figure 19 is an enlarged view of a portion of the first flow channel 311 shown in Figure 17. The plurality of protrusions 33p includes a second protrusion 33pa of one of the protrusions 33p. The plurality of recesses 33q includes a second recess 33qa of one of the recesses 33q. The distance L7 shown in Figure 19 is longer than the distance Lb. The distance Lb is the shortest distance between one side (third side 33) of the second flow channel 332 and another side (fourth side 34). The distance L7 is the shortest distance between the fourth line IL4 and the fifth line IL5 shown in Figure 19. The fourth line IL4 is a line extending in the first direction D1, tangent to the second protrusion 33pa (the top 33pt of the second protrusion 33pa). The fifth line IL5 is a line extending in the first direction D1, tangent to the second concave portion 33qa (the top 33qt of the second concave portion 33qa). The distance L7 is, for example, 5 mm or more and 30 mm or less. The distance L8 shown in Figure 19 is, for example, 30 mm or more and 140 mm or less. Distance L8 is the distance along the first direction D1 between points p7 and p8 shown in Figure 19. Point p7 is the intersection of the sixth line IL6 and the third vertical line V3. Point p8 is the intersection of the sixth line IL6 and the fourth vertical line V4. The sixth line IL6 is a line located between the fourth line IL4 and the fifth line IL5. The shortest distance between the fourth line IL4 and the sixth line IL6 is equal to the shortest distance between the fifth line IL5 and the sixth line IL6. The third vertical line V3 is a line passing through the second protrusion 33pa (the top 33pt of the second protrusion 33pa) and perpendicular to the fourth line IL4. The fourth vertical line V4 is a line passing through the second concave portion 33qa (the top 33qt of the second concave portion 33qa) and perpendicular to the fifth line IL5. In the example of Figure 19, the protrusions 33p (top 33pt) and 34p (top 34pt) are not arranged in the second direction D2. Similarly, the recesses 33q (top 33qt) and 34q (top 34qt) are not arranged in the second direction D2. That is, the width of the second flow channel 312 varies along the first direction. Accordingly, for example, turbulent flow of the refrigerant within the second flow channel 312 can improve the cooling effect. However, it is also possible for the protrusions 33p (top 33pt) and 34p (top 34pt) to be arranged in the second direction D2. Furthermore, it is also possible for the recesses 33q (top 33qt) and 34q (top 34qt) to be arranged in the second direction D2. As described above, depending on the embodiment, an electrostatic chuck can be provided that can suppress the influence of refrigerant channel displacement. For example, it can improve the uniformity of temperature distribution within the surface of the object being processed. The embodiments of the present invention have been described above. However, the present invention is not limited to these descriptions. Those skilled in the art can readily incorporate design changes to the foregoing embodiments, as long as they possess the features of the present invention, they are included within the scope of the present invention. For example, the shape, size, material, configuration, and arrangement of the components of an electrostatic chuck are not limited to the examples provided and can be appropriately modified. Furthermore, the elements in the aforementioned embodiments are technically combinable as much as possible, and any combination of these elements that also includes the features of the present invention is included within the scope of the present invention. 10-12: Electrostatic chuck 31: First side 31p, 31pb, 31pc, 32p, 33p, 34p, 113: Protrusion 31pa: First protrusion 31pt, 31qt, 32pt, 32qt, 33pt, 33q, 34pt, 34qt: Top 31q, 31qb, 31qc, 32q, 33q, 34q: Recess 31qa: First recess 32: Second side 33: Third side 33pa: Second protrusion 33qa: Second recess 34 Fourth side 100: Ceramic dielectric substrate 101: First main surface 102: Second main surface 111: Electrode layer 115: Trench 200: Heater section 230: Heater element 230a: First heater element 230b: Second heater element 231-239: First to ninth heater lines 300: Base plate 300a: Upper component 300af: Bottom surface 300b: Lower component 300bf: Top surface 300c: Center 300e: Outer periphery 300g: Trench 301: Connecting channel 3 01c: One end 301d: Other end 301g, 303: Bottom surface 301s: Side surface 301u, 302: Top surface 311: First flow channel section 311a: First part 311b: Second part 312: Second flow channel section 312a: Third part 312b: Fourth part 321: Inlet channel 332: Flow channel section 403: Adhesion layer B1: Region CR: Central region d: Distance Dα, Dβ: Direction D1~D3: First~Third direction D31p, D31q, D33p, D 33q: Direction DR1: First refrigerant direction DR2: Second refrigerant direction IC1~IC6: First~sixth imaginary circles IL1~IL6: First~sixth straight lines L, Lβ: Line segments L1~L8, La, Lb: Distance Ly: Straight line p1~p8: Points q1, q2: First and second sides R: Refrigerant R1~R4 - First~fourth radial lines Ra, Rb, Rc: Regions Rc1, Rc2: Parts V1~V4 - First~fourth vertical lines W: Object to be processed α, β: Point θ: Angle Figure 1 is a perspective view schematically showing an electrostatic chuck related to the embodiment. Figures 2(a) and 2(b) are cross-sectional views schematically showing a portion of an electrostatic chuck related to the embodiment. Figures 3(a) and 3(b) are cross-sectional views schematically showing a portion of an electrostatic chuck related to a modified example of the embodiment. Figure 4 is a cross-sectional view schematically showing a portion of an electrostatic chuck related to the embodiment. Figure 5 is a cross-sectional view schematically showing a portion of an electrostatic chuck related to the embodiment. Figure 6 is a cross-sectional view schematically showing a portion of an electrostatic chuck related to the embodiment. Figures 7(a) to 7(f) are schematic cross-sectional views showing an example of a manufacturing method of an electrostatic chuck related to the embodiment. Figures 8(a) to 8(d) are schematic diagrams showing a simulation of the temperature distribution of the electrostatic chuck. Figures 9(a) to 9(f) are schematic diagrams showing a simulation of the temperature distribution of the electrostatic chuck. Figure 10 is a perspective view schematically showing a portion of an electrostatic chuck related to the embodiment. Figures 11(a) and 11(b) are perspective top views schematically showing a portion of an electrostatic chuck related to an embodiment. Figure 12 is a cross-sectional view schematically showing a portion of another electrostatic chuck related to an embodiment. Figure 13 is a cross-sectional view schematically showing a portion of an electrostatic chuck related to an embodiment. Figure 14 is a cross-sectional view schematically showing a portion of an electrostatic chuck related to an embodiment. Figure 15 is a perspective top view schematically showing a portion of an electrostatic chuck related to an embodiment. Figures 16(a) and 16(b) are perspective top views schematically showing a portion of an electrostatic chuck related to an embodiment. Figure 17 is a cross-sectional view schematically showing a portion of another electrostatic chuck related to an embodiment. Figure 18 is a cross-sectional view schematically showing a portion of another electrostatic chuck related to an embodiment. Figure 19 is a cross-sectional view schematically showing a portion of another electrostatic chuck related to an embodiment. 31: First side view 31p, 31pb, 31pc, 32p: convex part 31pt, 31qt: Top 31q, 31qb, 31qc, 32q: concave part 32: Second side view 300: Base Plate 300a: Upper component 300c: Center 300g: groove 301c: One end 301d: Other side 301s: Side View 311: First Flow Section CR: Central Region D1~D3: First to Third Directions D31p, D31q: Direction DR1: First refrigerant direction R:Refrigerant

Claims

1. An electrostatic chuck, characterized in that it comprises: a ceramic dielectric substrate having a mounting surface for placing an object to be processed; and a base plate supporting the ceramic dielectric substrate, having a top surface on the side of the ceramic dielectric substrate and a bottom surface opposite to the top surface, the base plate including a connecting channel disposed between the top surface and the bottom surface through which a cooling medium can pass, the connecting channel including a first flow channel portion having a pair of side surfaces along a first direction along the flow of the cooling medium, one of the pair of side surfaces having, when viewed along the stacking direction of the base plate and the ceramic dielectric substrate: a plurality of protrusions convex in a second direction perpendicular to the first direction and convex in a direction from the other side of the pair of side surfaces toward the side surface of the first surface; and a plurality of convex recesses convex in a direction opposite to the second direction, the plurality of protrusions and the plurality of recesses being alternately arranged. It further includes: a heater portion disposed inside the ceramic dielectric substrate, or disposed between the ceramic dielectric substrate and the base plate, for heating the ceramic dielectric substrate, the heater portion including heater lines, the heater lines having a pair of sides extending in the same direction as the first direction, at least a portion of one of the pairs of sides overlapping the first flow channel portion in the lamination direction.

2. The electrostatic chuck of claim 1, wherein the other side of the pair of sides, when viewed along the stacking direction, has: a plurality of convex portions protruding in the second direction; and a plurality of convex recesses protruding in the direction opposite to the second direction, wherein the plurality of convex portions and the plurality of recesses of the other side are arranged alternately.

3. The electrostatic chuck of claim 1 or claim 2, wherein the first direction is the circumferential direction of the base plate, the plurality of protrusions on one side of the plate include a first protrusion, the plurality of recesses on one side of the plate include a first recess adjacent to the first protrusion, and in the case where an imaginary circle tangent to the first protrusion and centered on the center of the base plate is used as the first imaginary circle, and an imaginary circle tangent to the first recess and centered on the center of the base plate is used as the second imaginary circle, the first distance between the first imaginary circle and the second imaginary circle is longer than the shortest distance between one side of the plate and the other side of the plate.

4. The electrostatic chuck as requested in item 3, wherein the first distance is 5 mm or more.

5. The electrostatic chuck of claim 1 or claim 2, wherein the first direction is the circumferential direction of the base plate, the plurality of protrusions on one side of the plate include a first protrusion, the plurality of recesses on one side of the plate include a first recess adjacent to the first protrusion, and in the case where an imaginary circle tangent to the first protrusion and centered on the center of the base plate is used as a first imaginary circle, an imaginary circle tangent to the first recess and centered on the center of the base plate is used as a second imaginary circle, an imaginary circle at a distance equal to the distance from the first imaginary circle and the distance from the second imaginary circle is used as a third imaginary circle, a straight line connecting the first protrusion and the center of the base plate is used as a first radial line, and a straight line connecting the first recess and the center of the base plate is used as a second radial line, the second distance along the circumferential direction between the intersection point of the first radial line and the third imaginary circle and the intersection point of the second radial line and the third imaginary circle is 30 mm or more and 140 mm or less.

6. The electrostatic chuck of claim 1 or claim 2, wherein the first direction is the circumferential direction of the base plate, and one side is located on the outer periphery of the base plate further than the other side.

7. The electrostatic chuck of claim 3, wherein the connecting channel includes a second flow channel portion having a pair of side surfaces arranged radially in the base plate, one of the side surfaces of the second flow channel portion having, when viewed along the stacking direction, a plurality of convex protrusions convex in the second direction and a plurality of convex recesses convex in the direction opposite to the second direction, the plurality of convex protrusions and the plurality of recesses of the second flow channel portion being alternately arranged, the second flow channel portion being located on the inner periphery of the base plate further than the first flow channel portion, the plurality of convex protrusions of the second flow channel portion including second convex protrusions, and the plurality of recesses of the second flow channel portion including second recesses. If the imaginary circle tangent to the second protrusion and centered on the center of the base plate is taken as the fourth imaginary circle, and the imaginary circle tangent to the second concave portion and centered on the center of the base plate is taken as the fifth imaginary circle, then the distance between the fourth imaginary circle and the fifth imaginary circle is taken as the third distance, then the first distance is longer than the third distance.

8. The electrostatic chuck of claim 5, wherein the connecting channel includes a second flow channel portion having a pair of side surfaces arranged radially in the base plate, one of the side surfaces of the second flow channel portion having, when viewed along the stacking direction, a plurality of convex protrusions convex in the second direction and a plurality of convex recesses convex in the direction opposite to the second direction, the plurality of convex protrusions and the plurality of recesses of the second flow channel portion being alternately arranged, the second flow channel portion being located on the inner periphery of the base plate further than the first flow channel portion, the plurality of convex protrusions of the second flow channel portion including second convex protrusions, and the plurality of recesses of the second flow channel portion including second recesses. If we take the imaginary circle tangent to the second protrusion and centered on the center of the base plate as the fourth imaginary circle, the imaginary circle tangent to the second concave portion and centered on the center of the base plate as the fifth imaginary circle, the imaginary circle whose distance from the fourth imaginary circle is equal to the distance from the fifth imaginary circle as the sixth imaginary circle, the straight line connecting the second protrusion and the center of the base plate as the third radial line, and the straight line connecting the second concave portion and the center of the base plate as the fourth radial line, and the distance along the circumference between the intersection of the third radial line and the sixth imaginary circle and the intersection of the fourth radial line and the sixth imaginary circle as the fourth distance, then the second distance is shorter than the fourth distance.

9. An electrostatic chuck as claimed in claim 1 or claim 2, wherein the first direction is a straight line direction, the plurality of protrusions on one side of the chuck include a first protrusion, the plurality of recesses on one side of the chuck include a first recess adjacent to the first protrusion, and in the case where a first straight line is defined as a straight line tangent to the first protrusion and extending in the first direction, and a second straight line is defined as a straight line tangent to the first recess and extending in the first direction, the fifth distance between the first straight line and the second straight line is longer than the shortest distance between one side of the chuck and the other side of the chuck.

10. The electrostatic chuck of claim 9, wherein the fifth distance is 5 mm or more.

11. An electrostatic chuck as claimed in claim 1 or claim 2, wherein the first direction is a straight direction, the plurality of protrusions on one side of the chuck include a first protrusion, the plurality of recesses on one side of the chuck include a first recess adjacent to the first protrusion, and in the case where a straight line tangent to the first protrusion and extending in the first direction is used as a first straight line, a straight line tangent to the first recess and extending in the first direction is used as a second straight line, a straight line at a distance equal to the distance from the first straight line and the distance from the second straight line is used as a third straight line, a straight line passing through the first protrusion and perpendicular to the first straight line is used as a first vertical line, and a straight line passing through the first recess and perpendicular to the second straight line is used as a second vertical line, the sixth distance between the intersection of the first vertical line and the third straight line and the intersection of the second vertical line and the third straight line is 30 mm or more and 140 mm or less.

Images