Retainer

Abstract

To provide a retainer capable of improving thermal uniformity on a surface for holding an object.SOLUTION: According to one aspect of the present disclosure, in an electrostatic chuck 1, a chuck electrode 40, a plurality of vias 50 for supplying a power to the chuck electrode 40, and a plurality of connection pads 60 are disposed inside a plate-shaped member 10. A space part 13 is formed in a lower surface 12 of the plate-shaped member 10. Among the plurality of vias 50, the vias 50 disposed at the same height position from a retainer surface 11 and connected to the chuck electrode 40 include a reference via 50A in which a refrigerant flow path 23 is located directly below and vias 50B and 50C in which the refrigerant flow path 23 is not located directly below, and an area (S) of the reference via 50A and an area (S) of the vias 50B and 50C are different from each other.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to a holding device for holding an object. [Background technology]

[0002] Patent Document 1 discloses a holding device (electrostatic chuck) in which a plurality of vias and a plurality of connection pads (internal wiring layers or intermediate conductive layers) for supplying power to an internal electrode are arranged inside a plate-shaped member (ceramic substrate). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-228361 Summary of the Invention [Problem to be solved by the invention]

[0004] In the holding device disclosed in Patent Document 1, the vias and connection pads generate heat, but the heat from the vias and connection pads is drawn by the coolant flowing through the coolant flow path (cooling path) in the base member (metal base). However, the amount of heat drawn by the coolant flowing through the coolant flow path differs between vias and connection pads that have a coolant flow path directly below them and vias and connection pads that do not have a coolant flow path directly below them.

[0005] In particular, if the amount of heat drawn differs between multiple vias and connection pads that are connected to the same internal electrode (e.g., chuck electrode) and are positioned at the same height from the surface that holds the object, a significant temperature difference will occur on the surface that holds the object between the positions of vias and connection pads that have a coolant flow path directly below them and the positions of vias and connection pads that do not have a coolant flow path directly below them.As a result, it is not possible to uniformize the temperature distribution on the surface that holds the object, and the thermal uniformity on the surface that holds the object will decrease.

[0006] Therefore, the present disclosure has been made to solve the above-mentioned problems, and aims to provide a holding device that can improve the thermal uniformity on the surface that holds the object. [Means for solving the problem]

[0007] In one embodiment of the present disclosure made to solve the above problem, in a holding device comprising a plate-shaped member having a first surface and a second surface provided on the opposite side of the first surface in a thickness direction from the first surface, and a coolant flow path for flowing a coolant, the holding device holding an object on the first surface, the plate-shaped member having an internal electrode, a plurality of vias for feeding power to the internal electrode, a plurality of connection pads, and a space disposed therein, the plurality of vias being disposed at the same height from the first surface and connected to the internal electrode, including a first via that is disposed at a position not overlapping the coolant flow path as viewed in the thickness direction and connected to one of the connection pads, and a second via that is disposed at a position overlapping the coolant flow path as viewed in the thickness direction and connected to one of the connection pads. and a second via connected to another one of the pads, wherein the area of ​​the first via when viewed in the thickness direction is different from the area of ​​the second via when viewed in the thickness direction; or, among the plurality of vias that are arranged at the same height from the first surface and connected to the internal electrode, there is included a third via that is arranged in a position that does not overlap the space when viewed in the thickness direction and is connected to one of the connection pads, and a fourth via that is arranged in a position that overlaps the space when viewed in the thickness direction and is connected to another one of the connection pads, wherein the area of ​​the third via when viewed in the thickness direction is different from the area of ​​the fourth via when viewed in the thickness direction.

[0008] According to this aspect, it is possible to adjust the amount of heat generated in each of the first and second vias, or the amount of heat generated in each of the third and fourth vias. As a result, it is possible to reduce the temperature difference between the arrangement positions of the first and second vias, or the temperature difference between the arrangement positions of the third and fourth vias, on the first surface. Therefore, it is possible to make the temperature distribution on the first surface uniform, thereby improving the thermal uniformity on the first surface.

[0009] Another aspect of the present disclosure made to solve the above problem is a holding device comprising a plate-like member having a first surface and a second surface provided on the opposite side of the first surface in a thickness direction from the first surface, and a coolant flow path for flowing a coolant, the holding device holding an object on the first surface, wherein an internal electrode, a plurality of vias for feeding power to the internal electrode, a plurality of connection pads, and a space are arranged inside the plate-like member, and the connection pads among the plurality of connection pads are arranged at the same height position from the first surface and connected to the internal electrode, and include a first connection pad arranged at a position that does not overlap the coolant flow path when viewed in the thickness direction, and a second connection pad arranged at a position that overlaps the coolant flow path when viewed in the thickness direction. and a second connection pad arranged at a position where the first connection pad overlaps the space portion when viewed in the thickness direction, and an area of ​​the first connection pad when viewed in the thickness direction is different from an area of ​​the second connection pad when viewed in the thickness direction; or, among the plurality of connection pads, the connection pads arranged at the same height from the first surface and connected to the internal electrode include a third connection pad arranged at a position that does not overlap the space portion when viewed in the thickness direction, and a fourth connection pad arranged at a position that overlaps the space portion when viewed in the thickness direction, and an area of ​​the third connection pad when viewed in the thickness direction is different from an area of ​​the fourth connection pad when viewed in the thickness direction.

[0010] According to this aspect, it is possible to adjust the amount of heat generated by each of the first and second connection pads, or the amount of heat generated by each of the third and fourth connection pads. Therefore, it is possible to reduce the temperature difference between the positions of the first and second connection pads, or the temperature difference between the positions of the third and fourth connection pads, on the first surface. Therefore, it is possible to make the temperature distribution on the first surface uniform, thereby improving the thermal uniformity on the first surface.

[0011] Here, when there are multiple first vias or third vias, possible methods for changing the area of ​​the first vias or third vias include changing the number of first vias or third vias, or changing the diameter (thickness) of the first vias or third vias.

[0012] Therefore, in the above-mentioned aspect, it is preferable that the number of the first vias and the second vias are the same, the first vias and the second vias are each circular when viewed in the thickness direction, and the first vias and the second vias have different diameters when viewed in the thickness direction, or that the number of the third vias and the fourth vias are the same, the third vias and the fourth vias are each circular when viewed in the thickness direction, and the third vias and the fourth vias have different diameters when viewed in the thickness direction.

[0013] According to this aspect, since only the diameter of the via is changed, the manufacturing process of the holding device can be hardly changed, and therefore the temperature uniformity on the first surface can be improved without increasing manufacturing costs.

[0014] Furthermore, since the chuck electrode is often subjected to a larger voltage than the internal electrodes, the vias or connection pads connected to the chuck electrode generate a larger amount of heat, which tends to increase the temperature difference between the positions of the first and second connection pads, or between the positions of the third and fourth connection pads, on the first surface.

[0015] Therefore, in the above aspect, it is preferable that the internal electrode is a chuck electrode.

[0016] According to this aspect, by changing the area, as viewed in the thickness direction, of the via or connection pad connected to the chuck electrode to which a large voltage is applied, it is possible to minimize the influence on the temperature distribution on the first surface, thereby improving the thermal uniformity on the first surface.

[0017] In the above aspect, it is preferable that the ratio of the area of ​​the first via as viewed in the thickness direction to the area of ​​the second via as viewed in the thickness direction is 1.3 or more, or the ratio of the area of ​​the first connection pad as viewed in the thickness direction to the area of ​​the second connection pad as viewed in the thickness direction is 1.3 or more, or the ratio of the area of ​​the third via as viewed in the thickness direction to the area of ​​the fourth via as viewed in the thickness direction is 1.3 or more, or the ratio of the area of ​​the third connection pad as viewed in the thickness direction to the area of ​​the fourth connection pad as viewed in the thickness direction is 1.3 or more.

[0018] According to this aspect, if the area ratio is less than 1.3, there is a risk that it will fall within the range of product tolerance, and there is a risk that the thermal uniformity on the first surface will not be improved. Therefore, by setting the area ratio to 1.3 or more (preferably 1.5 or more), it is possible to reliably improve the thermal uniformity on the first surface. [Effects of the Invention]

[0019] According to the holding device of the present disclosure, it is possible to improve the thermal uniformity on the surface that holds the object. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic perspective view of an electrostatic chuck according to an embodiment of the present invention. [Figure 2] 1 is a schematic configuration diagram of an XZ cross section of an electrostatic chuck according to an embodiment of the present invention. [Figure 3]FIG. 2 is a diagram showing the electrostatic chuck of the present embodiment as viewed from the Z-axis direction, illustrating the positional relationship between vias and connection pads, a coolant flow path, and a space portion. [Figure 4] 10 is a table showing the presence or absence of a coolant flow path directly below, the presence or absence of a space directly below, and the occurrence or absence of temperature singularities for a reference via and connection pad and a via and connection pad of a comparative example in the first proposal of the first embodiment. [Figure 5] FIG. 5 is a schematic diagram of an XZ cross section of an electrostatic chuck illustrating the contents of FIG. 4. [Figure 6] 10 is a table showing the presence or absence of a coolant flow path directly below, the presence or absence of a space directly below, and the occurrence or absence of a temperature singularity for the reference via and connection pad and the via and connection pad of the embodiment in the first proposal of the first embodiment. [Figure 7] FIG. 7 is a schematic diagram of an XZ cross section of an electrostatic chuck illustrating the contents of FIG. 6. [Figure 8] 10 is a table showing the presence or absence of a coolant flow path directly below, the presence or absence of a space directly below, and the occurrence or absence of temperature singularities for the reference via and connection pad and the via and connection pad of the comparative example in the second design of the first embodiment. [Figure 9] FIG. 9 is a schematic diagram of the XZ cross section of the electrostatic chuck illustrating the contents of FIG. 8. [Figure 10] This is a table showing the presence or absence of a coolant flow path directly below, the presence or absence of a space directly below, and the occurrence or absence of a temperature singularity for the reference via and connection pad and the via and connection pad of the embodiment in the second proposal of the first embodiment. [Figure 11] 11 is a schematic diagram of an XZ cross section of an electrostatic chuck illustrating the contents of FIG. 10. FIG. [Figure 12] This is a table showing the presence or absence of a coolant flow path directly below, the presence or absence of a space directly below, and the occurrence or absence of temperature singularities for the reference via and connection pad and the via and connection pad of the comparative example in the first proposal of the second embodiment. [Figure 13] FIG. 13 is a schematic diagram of the XZ cross section of the electrostatic chuck illustrating the contents of FIG. 12. [Figure 14]This is a table that explains the presence or absence of a coolant flow path directly below, the presence or absence of a space directly below, and the occurrence or absence of a temperature singularity for the reference via and connection pad and the via and connection pad of the embodiment in the first proposal of the second embodiment. [Figure 15] 15 is a schematic diagram of the XZ cross section of the electrostatic chuck illustrating the contents of FIG. 14. FIG. [Figure 16] This is a table showing the presence or absence of a coolant flow path directly below, the presence or absence of a space directly below, and the occurrence or absence of temperature singularities for the reference via and connection pad and the via and connection pad of the comparative example in the second design of the second embodiment. [Figure 17] FIG. 17 is a schematic diagram of the XZ cross section of the electrostatic chuck illustrating the contents of FIG. 16. [Figure 18] This is a table that explains the presence or absence of a coolant flow path directly below, the presence or absence of a space directly below, and the occurrence or absence of temperature singularities for the reference vias and connection pads and the vias and connection pads of the embodiment in the second proposal of the second embodiment. [Figure 19] FIG. 19 is a schematic diagram of the XZ cross section of the electrostatic chuck illustrating the contents of FIG. 18. DETAILED DESCRIPTION OF THE INVENTION

[0021] (Description of the holding device) An embodiment of a holding device according to the present disclosure will be described. In this embodiment, the holding device will be described by taking as an example an electrostatic chuck used in semiconductor manufacturing equipment such as a film forming apparatus (such as a CVD film forming apparatus or a sputtering film forming apparatus) or an etching apparatus (such as a plasma etching apparatus).

[0022] The electrostatic chuck 1 of this embodiment is a device that attracts and holds a semiconductor wafer W (object) by electrostatic attraction, and is used, for example, to fix the semiconductor wafer W in a vacuum chamber of a semiconductor manufacturing device.

[0023] In the following description, for convenience of explanation, the X, Y, and Z axes are defined as shown in Fig. 1. Here, the Z axis is an axis in the axial direction of the electrostatic chuck 1 (the vertical direction in Fig. 1), and the Z axis direction is an example of the "thickness direction" in the present disclosure. The X and Y axes are axes in the radial direction of the electrostatic chuck 1.

[0024] As shown in FIG. 1, the electrostatic chuck 1 includes a plate-shaped member 10, a base member 20, and a bonding layer 30 that bonds the plate-shaped member 10 and the base member 20 together.

[0025] As shown in Fig. 1, the plate-shaped member 10 is a disc-shaped member made of ceramic. Specifically, the plate-shaped member 10 has a stepped disc shape in which two discs of different diameters are stacked on top of each other with a common central axis (more specifically, a disc-shaped upper section 10a having a smaller diameter is stacked on top of a disc-shaped lower section 10b having a larger diameter). In this way, the lower section 10b is provided on the opposite side of the holding surface 11 side with respect to the upper section 10a in the thickness direction of the plate-shaped member 10 (a direction corresponding to the Z-axis direction, a vertical direction), and has a larger outer periphery than the upper section 10a when viewed in the thickness direction of the plate-shaped member 10.

[0026] Although various ceramics are used as the ceramic, it is preferable to use ceramics whose main component is, for example, aluminum oxide (alumina, Al2O3) or aluminum nitride (AlN) from the viewpoint of strength, wear resistance, plasma resistance, etc. The main component here means the component with the highest content (for example, a component with a volume content of 90 vol% or more).

[0027] 1 and 2, the plate-shaped member 10 has a holding surface 11 (upper surface) that holds the semiconductor wafer W, and a lower surface 12 that is provided on the opposite side of the holding surface 11 in the thickness direction (i.e., the Z-axis direction) of the plate-shaped member 10. In this embodiment, the upper step portion 10a has the holding surface 11, and the semiconductor wafer W is held on the holding surface 11. The holding surface 11 is an example of a "first surface" in the present disclosure, and the lower surface 12 is an example of a "second surface" in the present disclosure.

[0028] 2, a space 13 is formed on the lower surface 12 of the plate-like member 10 so as to be recessed toward the holding surface 11. A power supply terminal (not shown) for supplying power to, for example, a chuck electrode 40 (described later), a heater electrode, or other electrodes is disposed in this space 13.

[0029] Here, the diameter of the lower portion 10b of the plate-shaped member 10 is larger than that of the upper portion 10a, and the upper portion 10a has a diameter of, for example, about 150 mm to 300 mm, while the lower portion 10b has a diameter of, for example, about 180 mm to 400 mm. The thickness of the plate-shaped member 10 is, for example, about 2 mm to 6 mm. The thermal conductivity of the plate-shaped member 10 is preferably within a range of 10 W / mK to 50 W / mK (more preferably, 18 W / mK to 30 W / mK).

[0030] 2, a chuck electrode 40 is disposed inside the plate-like member 10. The chuck electrode 40 has, for example, a substantially circular shape when viewed in the Z-axis direction (i.e., when viewed in the thickness direction) and is made of a conductive material (e.g., tungsten, molybdenum, etc.). In this manner, the electrostatic chuck 1 is configured to supply power to the chuck electrode 40 to generate an electrostatic attractive force, thereby holding the semiconductor wafer W on the holding surface 11 by the electrostatic attractive force. The chuck electrode 40 is an example of an "internal electrode" in the present disclosure.

[0031] A plurality of vias 50 and a plurality of connection pads 60, which are conductors for supplying power to the chuck electrode 40, are arranged inside the plate-like member 10. A voltage is applied to the chuck electrode 40 from a power supply through the vias 50, the connection pads 60, and a power supply terminal connected to the power supply (not shown).

[0032] 2 shows only the vias 50 and the connection pads 60 arranged at the same height position (i.e., the same position in the Z-axis direction) from the holding surface 11, but in reality, the vias 50 and the connection pads 60 are also arranged at different height positions from the holding surface 11. Although not shown, the vias 50 and the connection pads 60 are also arranged for supplying power to electrodes other than the chuck electrode 40 (for example, heater electrodes).

[0033] 2, the via 50 is arranged to extend in the Z-axis direction, and both ends are connected to the connection pads 60. As a result, the two connection pads 60 are electrically connected via the via 50. In this manner, the power supply terminal is electrically connected to the chuck electrode 40 via the multiple vias 50 and the connection pads 60. The via 50 is formed in a circular shape when viewed in the thickness direction.

[0034] 2 and 3, the vias 50 and the connection pads 60 are formed to have different areas and numbers depending on the electrodes to be connected. For example, as shown in Fig. 3, the vias 50 and the connection pads 60 are formed in a "purpose α" connected to the chuck electrode 40, a "purpose β" connected to the heater electrode, and a "purpose γ" connected to another electrode.

[0035] 1 and 2, the base member 20 is disposed on the side of the plate-like member 10 opposite the holding surface 11. The base member 20 is formed, for example, in a cylindrical shape. The base member 20 is formed, for example, from a metal (for example, aluminum or an aluminum alloy), but may be formed from a material other than metal.

[0036] 1 and 2, the base member 20 has an upper surface 21 and a lower surface 22 provided on the opposite side to the upper surface 21 in the thickness direction (i.e., the Z-axis direction) of the base member 20. The upper surface 21 of the base member 20 is thermally connected to the lower surface 12 of the plate-like member 10 via a bonding layer 30.

[0037] The diameter of the base member 20 is, for example, about 180 mm to 400 mm. The thickness (dimension in the Z-axis direction) of the base member 20 is, for example, about 20 mm to 50 mm. The thermal conductivity of the base member 20 (assumed to be made of aluminum) is preferably within the range of 160 mm to 250 W / mK (preferably about 230 W / mK).

[0038] 2 and 3, the base member 20 is formed with a coolant flow path 23 for flowing a coolant (e.g., a fluorine-based inert liquid, water, etc.). By flowing a coolant through this coolant flow path 23, the base member 20 is cooled, and the plate-like member 10 is cooled via the bonding layer 30. This allows the semiconductor wafer W held on the holding surface 11 to be cooled, and the electrostatic chuck 1 allows temperature control of the semiconductor wafer W by heating with a heater electrode (not shown). Note that the vias 50 and the connection pads 60 generate heat, but the heat is absorbed by the coolant flowing through the coolant flow path 23.

[0039] 1 and 2, the bonding layer 30 is disposed between the lower surface 12 of the plate-shaped member 10 and the upper surface 21 of the base member 20, and bonds the plate-shaped member 10 and the base member 20 in a heat-transferable manner. The bonding layer 30 is made of a resin adhesive such as a silicone resin, an acrylic resin, or an epoxy resin.

[0040] The thickness (dimension in the Z-axis direction) of the bonding layer 30 is, for example, about 0.1 mm to 1.5 mm. The thermal conductivity of the bonding layer 30 is, for example, 1.0 W / mK. The thermal conductivity of the bonding layer 30 (assumed to be a silicone-based resin) is preferably within the range of 0.1 W / mK to 2.0 W / mK (preferably 0.5 W / mK to 1.5 W / mK).

[0041] (Regarding vias and connection pads) Next, the vias 50 and the connection pads 60 will be described.

[0042] <First Example> First, the first embodiment will be described.

[0043] The heat generated in the vias 50 and the connection pads 60 is drawn by the coolant flowing through the coolant flow paths 23 in the base member 20. However, among the multiple vias 50 and connection pads 60 provided, there are vias 50 and connection pads 60 that do not have a coolant flow path 23 directly below, and vias 50 and connection pads 60 that have a coolant flow path 23 directly below, as shown in Figures 2 and 3 .

[0044] Therefore, the amount of heat drawn by the refrigerant flowing through the refrigerant flow path 23 differs between vias 50 and connection pads 60 that are not directly below the refrigerant flow path 23 and vias 50 and connection pads 60 that are directly below the refrigerant flow path 23. In other words, the vias 50 and connection pads 60 that are directly below the refrigerant flow path 23 are positioned closer to the refrigerant flow path 23 than the vias 50 and connection pads 60 that are not directly below the refrigerant flow path 23, and therefore the heat is more easily drawn therefrom.

[0045] Therefore, a temperature difference occurs on the holding surface 11 between the positions of the vias 50 and the connection pads 60 that are not directly below the refrigerant flow path 23 and the positions of the vias 50 and the connection pads 60 that are directly below the refrigerant flow path 23. That is, the positions of the vias 50 and the connection pads 60 that are not directly below the refrigerant flow path 23 have a lower amount of heat drawn by the refrigerant flowing through the refrigerant flow path 23, and therefore the temperature becomes higher at these positions than at the positions of the vias 50 and the connection pads 60 that are directly below the refrigerant flow path 23.

[0046] In particular, if the amount of heat drawn differs as described above for multiple vias 50 and connection pads 60 that are connected to the same internal electrode (e.g., chuck electrode 40) and arranged at the same height from the holding surface 11, a significant temperature difference occurs between the positions on the holding surface 11 where the vias 50 and connection pads 60 are not directly below the refrigerant flow path 23 and the positions on the holding surface 11 where the refrigerant flow path 23 is directly below. Therefore, the temperature distribution on the holding surface 11 cannot be made uniform, and the thermal uniformity on the holding surface 11 decreases.

[0047] The vias 50 and connection pads 60 that are not directly below the coolant flow path 23 refer to the vias 50 and connection pads 60 that are arranged at positions that do not overlap the coolant flow path 23 when viewed in the thickness direction (i.e., when the electrostatic chuck 1 is viewed from the Z-axis direction). The vias 50 and connection pads 60 that are directly below the coolant flow path 23 refer to the vias 50 and connection pads 60 that are arranged at positions that overlap the coolant flow path 23 when viewed in the thickness direction. The vias 50 that are not directly below the coolant flow path 23 are connected to one of the multiple connection pads 60, and the vias 50 that are directly below the coolant flow path 23 are connected to another one of the multiple connection pads 60.

[0048] Therefore, in this embodiment, for the vias 50 among the plurality of vias 50 that are arranged at the same height position from the holding surface 11 and have the same purpose, i.e., the vias 50 that are connected to the same internal electrode (for example, the chuck electrode 40), the area S (i.e., the area as viewed in the thickness direction) of the vias 50 that do not have the refrigerant flow path 23 directly below is made different from the area S of the vias 50 that have the refrigerant flow path 23 directly below. In other words, the area S of the vias 50 that have the refrigerant flow path 23 directly below is made smaller than the area S of the vias 50 that do not have the refrigerant flow path 23 directly below.

[0049] The area S is the total area obtained by adding up the areas of all the vias 50 connected to one connection pad 60. On the other hand, the area S1 described below is the area of ​​one via 50.

[0050] In this way, by making the area S of the vias 50 directly below which the refrigerant flow path 23 is located smaller than the area S of the vias 50 not directly below which the refrigerant flow path 23 is located, the vias 50 directly below which the refrigerant flow path 23 is located will generate more heat than the vias 50 not directly below which the refrigerant flow path 23 is located. However, the vias 50 directly below which the refrigerant flow path 23 is located will have a greater amount of heat drawn by the refrigerant flowing through the refrigerant flow path 23 than the vias 50 not directly below which the refrigerant flow path 23 is located. Therefore, on the holding surface 11, a temperature difference is less likely to occur between the positions of the vias 50 not directly below which the refrigerant flow path 23 is located and the positions of the vias 50 directly below which the refrigerant flow path 23 is located, and it is possible to prevent the occurrence of temperature singularities.

[0051] Since the vias 50 have an elongated shape and a small area, the amount of heat generated can easily change depending on the area. Therefore, by adjusting the area of ​​the vias 50, it is easy to obtain the effect of uniform temperature distribution on the support surface 11.

[0052] Furthermore, a via 50 that does not have a coolant flow path 23 directly below it is an example of a "first via" in the present disclosure, and a via 50 that has a coolant flow path 23 directly below it is an example of a "second via" in the present disclosure.

[0053] Furthermore, in this embodiment, as another method, among the multiple connection pads 60, for the connection pads 60 that are arranged at the same height position from the holding surface 11 and have the same purpose, i.e., the connection pads 60 that are connected to the same internal electrode (e.g., the chuck electrode 40), the area (i.e., the area as viewed in the thickness direction) of the connection pads 60 that do not have the refrigerant flow path 23 directly below may be made different from the area of ​​the connection pads 60 that have the refrigerant flow path 23 directly below. In other words, the area of ​​the connection pads 60 that have the refrigerant flow path 23 directly below may be made smaller than the area of ​​the connection pads 60 that do not have the refrigerant flow path 23 directly below. Note that the area of ​​the connection pad 60 referred to here is the area of ​​one connection pad 60.

[0054] In this way, by making the area of ​​the connection pads 60 directly below which the refrigerant flow path 23 is located smaller than the area of ​​the connection pads 60 not directly below which the refrigerant flow path 23 is located, the connection pads 60 directly below which the refrigerant flow path 23 is located will generate more heat than the connection pads 60 not directly below which the refrigerant flow path 23 is located. However, the connection pads 60 directly below which the refrigerant flow path 23 is located will absorb a greater amount of heat from the refrigerant flowing through the refrigerant flow path 23 than the connection pads 60 not directly below which the refrigerant flow path 23 is located. Therefore, on the holding surface 11, a temperature difference is less likely to occur between the positions of the connection pads 60 not directly below which the refrigerant flow path 23 is located and the positions of the connection pads 60 directly below which the refrigerant flow path 23 is located, and it is possible to prevent the occurrence of temperature singularities.

[0055] Note that a connection pad 60 that does not have a refrigerant flow path 23 directly below it is an example of a "first connection pad" in the present disclosure, and a connection pad 60 that has a refrigerant flow path 23 directly below it is an example of a "second connection pad" in the present disclosure.

[0056] Therefore, the specific contents of this embodiment will be described below.

[0057] In this embodiment, the via 50 and the connection pad 60 that do not have the coolant flow path 23 directly below are set as the reference via 50A and the reference connection pad 60A.

[0058] [Proposal 1: When there is a space directly below the reference via and reference connection pad] First, as a first proposal, we will explain the case where there is a space 13 directly below the reference via 50A and the reference connection pad 60A, as shown in (a) of Figure 4 and "a" of Figure 5, that is, the case where the via 50 and connection pad 60 that do not have a refrigerant flow path 23 directly below but have a space 13 directly below them are used as the reference via 50A and the reference connection pad 60A.

[0059] Note that Figure 5 and Figures 7, 9, 11, 13, 15, 17, and 19 described below do not represent the actual XZ cross section of the electrostatic chuck 1, but for the sake of convenience, are XZ cross sections that list and schematically represent various specifications of the vias 50 and connection pads 60.

[0060] In this case, as shown in (b) of Figure 4 and "b" of Figure 5, as a comparative example, suppose that vias 50B and connection pads 60B that are not directly below the space portion 13 but are directly below the refrigerant flow path 23 are set to the same specifications as the reference vias 50A and reference connection pads 60A. That is, suppose that the area of ​​the connection pads 60B is set to the same area as the reference connection pads 60A, the area S1 of one via 50B is set to the same area S1 of one reference via 50A, and the number of vias 50B is set to the same number as the number of reference vias 50A. In this case, as shown in (b) of Figure 4, temperature singularities occur on the holding surface 11 at the positions where the vias 50B and connection pads 60B are arranged.

[0061] In the "Temperature Singularity" column in Figure 4 and subsequent figures, "◯" indicates that no temperature singularity occurs, "△" indicates that a temperature singularity occurs, and "×" indicates that the temperature singularity occurs more significantly than "△".

[0062] Therefore, in this embodiment, the area S of via 50B directly below which refrigerant flow path 23 is located is made smaller than the area S of reference via 50A directly below which refrigerant flow path 23 is not located. Alternatively, the area of ​​connection pad 60B directly below which refrigerant flow path 23 is located is made smaller than the area of ​​reference connection pad 60A directly below which refrigerant flow path 23 is not located.

[0063] Specifically, as shown in Figure 6(b) and Figure 7(b), the number of vias 50B directly below which the refrigerant flow path 23 is located is reduced from the number of reference vias 50A that are not directly below which the refrigerant flow path 23 is located. For example, if the number of reference vias 50A is two, the number of vias 50B is reduced to one. In this case, the area of ​​the connection pad 60B is kept the same as the area of ​​the reference connection pad 60A, and the area S1 of one via 50B is kept the same as the area S1 of one reference via 50A.

[0064] In this way, the area S of the via 50B directly below which the refrigerant flow path 23 is located is made smaller than the area S of the reference via 50A which does not have the refrigerant flow path 23 directly below. As a result, the via 50B generates more heat than the reference via 50A, but the amount of heat drawn by the refrigerant flowing through the refrigerant flow path 23 is greater. Therefore, it is possible to reduce the temperature difference on the holding surface 11 between the arrangement position of the reference via 50A and the arrangement position of the via 50B.

[0065] 6(b), it is possible to prevent temperature singularities from occurring at the positions where the vias 50B and the connection pads 60B are arranged on the holding surface 11. Therefore, it is possible to make the temperature distribution on the holding surface 11 uniform, thereby improving the thermal uniformity on the holding surface 11.

[0066] Alternatively, as another method, as shown in (c) of FIG. 6 and "c" of FIG. 7, the area S1 of one via 50B may be made smaller than the area S1 of one reference via 50A. That is, the diameter of the via 50B (i.e., the diameter as viewed in the thickness direction (as viewed in the Z-axis direction)) may be made smaller than the diameter of the reference via 50A, so that the diameter of the reference via 50A and the diameter of the via 50B are different. In this case, the area of ​​the connection pad 60B is made the same as the area of ​​the reference connection pad 60A, and the number of vias 50B is made the same as the number of reference vias 50A. This also makes it possible to prevent temperature singularities from occurring at the positions of the vias 50B and the connection pads 60B on the support surface 11, as shown in (c) of FIG. 6.

[0067] Furthermore, as another method, the area of ​​the connection pad 60B may be made smaller than the area of ​​the reference connection pad 60A, as shown in (d) of Figure 6 and "d" of Figure 7. In this case, the area S1 of one via 50B is made the same as the area S1 of one reference via 50A, and the number of vias 50B is made the same as the number of reference vias 50A. This also makes it possible to prevent temperature singularities from occurring at the positions of the vias 50B and the connection pads 60B on the holding surface 11, as shown in (d) of Figure 6.

[0068] In this way, in this embodiment, the area S of the via 50B that has the refrigerant flow path 23 directly below it is made smaller than the area S of the reference via 50A that does not have the refrigerant flow path 23 directly below it, and in this case, for example, the ratio of the area S of the reference via 50A to the area S of the via 50B (i.e., (area S of the reference via 50A) / (area S of the via 50B)) is made to be 1.3 (preferably 1.5) or more.

[0069] Furthermore, in this embodiment, the area of ​​the connection pad 60B, which has the refrigerant flow path 23 directly below it, is made smaller than the area of ​​the reference connection pad 60A, which does not have the refrigerant flow path 23 directly below it, and in this case, for example, the ratio of the area of ​​the reference connection pad 60A to the area of ​​the connection pad 60B (i.e., (area of ​​the reference connection pad 60A) / (area of ​​the connection pad 60B)) is made 1.3 (preferably 1.5) or more.

[0070] 4(c) and 5(c), as another comparative example, suppose that the vias 50C and connection pads 60C directly below the space 13 and the refrigerant flow path 23 are set to the same specifications as the reference vias 50A and the reference connection pads 60A. That is, suppose that the area of ​​the connection pads 60C is set to the same area as the reference connection pads 60A, the area S1 of one via 50C is set to the same area S1 of one reference via 50A, and the number of vias 50C is set to the same number as the number of reference vias 50A. In this case, as shown in FIG. 4(c), temperature singularities occur at the positions of the vias 50C and the connection pads 60C on the holding surface 11.

[0071] Therefore, in this embodiment, as shown in (e) of Figure 6 and "e" of Figure 7, the number of vias 50C directly below which the refrigerant flow path 23 is located is reduced from the number of reference vias 50A that are not directly below which the refrigerant flow path 23 is located. For example, if the number of reference vias 50A is two, the number of vias 50C is reduced to one.

[0072] In this way, the area S of the via 50C directly below which the refrigerant flow path 23 is located is made smaller than the area S of the reference via 50A which does not have the refrigerant flow path 23 directly below. As a result, the via 50C generates more heat than the reference via 50A, but the amount of heat drawn by the refrigerant flowing through the refrigerant flow path 23 is greater. Therefore, it is possible to reduce the temperature difference on the holding surface 11 between the arrangement position of the reference via 50A and the arrangement position of the via 50C.

[0073] 6(e), it is possible to prevent temperature singularities from occurring at the positions where the vias 50C and the connection pads 60C are arranged on the holding surface 11. Therefore, it is possible to make the temperature distribution on the holding surface 11 uniform, thereby improving the thermal uniformity on the holding surface 11.

[0074] Alternatively, as another method, the area S1 of one via 50C may be made smaller than the area S1 of one reference via 50A, as shown in (f) of Figure 6 and "f" of Figure 7. This also makes it possible to prevent temperature singularities from occurring at the positions of the via 50C and the connection pad 60C on the holding surface 11, as shown in (f) of Figure 6.

[0075] Furthermore, as another method, the area of ​​the connection pad 60C may be made smaller than the area of ​​the reference connection pad 60A, as shown in (g) of Figure 6 and "g" of Figure 7. This also makes it possible to prevent temperature singularities from occurring at the positions of the via 50C and the connection pad 60C on the holding surface 11, as shown in (g) of Figure 6.

[0076] [Second option: When there is no space directly below the reference via and reference connection pad] Next, as a second proposal, we will explain the case where there is no space 13 directly below the reference via 50A and the reference connection pad 60A, as shown in (a) of Figure 8 and "a" of Figure 9, i.e., the case where the via 50 and the connection pad 60 that do not have the refrigerant flow path 23 and the space 13 directly below them are used as the reference via 50A and the reference connection pad 60A.

[0077] In this case, as shown in (b) of Figure 8 and "b" of Figure 9, as a comparative example, a via 50B and a connection pad 60B that are not directly below the space portion 13 but are directly below the refrigerant flow path 23 are set to the same specifications as the reference via 50A and the reference connection pad 60A. In this case, as shown in (b) of Figure 8, a temperature singularity occurs at the arrangement position of the via 50B and the connection pad 60B on the holding surface 11.

[0078] Therefore, in this embodiment, as shown in (b) of Figure 10 and "b" of Figure 11, the number of vias 50B that have a refrigerant flow path 23 directly below them is reduced from the number of standard vias 50A that do not have a refrigerant flow path 23 directly below them.

[0079] In this way, the area S of the via 50B directly below which the refrigerant flow path 23 is located is made smaller than the area S of the reference via 50A not directly below which the refrigerant flow path 23 is located. This makes it possible to prevent temperature singularities from occurring at the positions of the via 50B and the connection pad 60B on the holding surface 11, as shown in Fig. 10(b). This makes it possible to make the temperature distribution on the holding surface 11 uniform, thereby improving the thermal uniformity on the holding surface 11.

[0080] Alternatively, as another method, the area S1 of one via 50B may be made smaller than the area S1 of one reference via 50A, as shown in (c) of Figure 10 and "c" of Figure 11. This also makes it possible to prevent temperature singularities from occurring at the positions of the vias 50B and the connection pads 60B on the holding surface 11, as shown in (c) of Figure 10.

[0081] Furthermore, as another method, the area of ​​the connection pad 60B may be made smaller than the area of ​​the reference connection pad 60A, as shown in (d) of Figure 10 and "d" of Figure 11. This also makes it possible to prevent temperature singularities from occurring at the positions of the vias 50B and the connection pads 60B on the holding surface 11, as shown in (d) of Figure 10.

[0082] 8(c) and 9(c), as another comparative example, the via 50C and the connection pad 60C are assumed to have the same specifications as the reference via 50A and the reference connection pad 60A. In this case, as shown in FIG. 8(c), no temperature singularity occurs at the arrangement positions of the via 50C and the connection pad 60C on the holding surface 11. Therefore, in this embodiment, the via 50C and the connection pad 60C are assumed to have the same specifications as the reference via 50A and the reference connection pad 60A.

[0083] In this way, in this embodiment, the area S of the via 50C that has the refrigerant flow path 23 directly below it is made smaller than the area S of the reference via 50A that does not have the refrigerant flow path 23 directly below it, but for example, the ratio of the area S of the reference via 50A to the area S of the via 50C (i.e., (area S of the reference via 50A) / (area S of the via 50C)) is made to be 1.3 (preferably 1.5) or more.

[0084] Furthermore, in this embodiment, the area of ​​the connection pad 60C, which has the refrigerant flow path 23 directly below it, is made smaller than the area of ​​the reference connection pad 60A, which does not have the refrigerant flow path 23 directly below it, but for example, the ratio of the area of ​​the reference connection pad 60A to the area of ​​the connection pad 60C (i.e., (area of ​​the reference connection pad 60A) / (area of ​​the connection pad 60C)) is made 1.3 (preferably 1.5) or more.

[0085] [Effects of this Example] According to this embodiment, the area S of the reference via 50A, which does not have the coolant flow path 23 directly below it, is made different from the area S of the vias 50B and 50C, which have the coolant flow path 23 directly below them.

[0086] This makes it possible to adjust the amount of heat generated by the vias 50B and 50C and the reference via 50A. This reduces the temperature difference between the positions of the vias 50B and 50C and the position of the reference via 50A on the holding surface 11. This makes it possible to make the temperature distribution on the holding surface 11 uniform, thereby improving the temperature uniformity on the holding surface 11.

[0087] Here, when there are multiple vias 50B and multiple vias 50C, possible methods for changing the area S of the vias 50B and 50C include changing the number of vias 50B and 50C, or changing the diameter (thickness) of the vias 50B and 50C (i.e., the area S1 of one via 50B and one via 50C).

[0088] Therefore, the number of vias 50B and 50C may be the same as the number of reference vias 50A, but the diameters of the vias 50B and 50C may be different from the diameter of the reference via 50A.

[0089] In this way, by simply changing the diameters of the vias 50B and 50C, the area S1 of one of the vias 50B and 50C can be made different from the area S1 of one reference via 50A, with almost no change to the manufacturing process of the electrostatic chuck 1. Therefore, the temperature uniformity on the holding surface 11 can be improved without increasing the manufacturing cost.

[0090] Here, if the ratio of the area S of vias 50B and 50C to the area S of the reference via 50A is less than 1.3, it may fall within the range of product error, and the thermal uniformity on the holding surface 11 may not be improved.

[0091] Therefore, in this embodiment, the ratio of the area S of the vias 50B and 50C to the area S of the reference via 50A is set to 1.3 or more (preferably 1.5 or more).

[0092] This eliminates the risk of the error falling within the range of manufacturing tolerances, and the temperature uniformity on the holding surface 11 can be reliably improved.

[0093] Furthermore, the areas of the connection pads 60B and 60C may be different from the area of ​​the reference connection pad 60A.

[0094] This makes it possible to adjust the amount of heat generated by the connection pads 60B and 60C and the reference connection pad 60A, respectively. This makes it possible to reduce the temperature difference between the positions of the connection pads 60B and 60C and the position of the reference connection pad 60A on the holding surface 11. This makes it possible to make the temperature distribution on the holding surface 11 uniform, thereby improving the temperature uniformity on the holding surface 11.

[0095] In this embodiment, the ratio of the area of ​​the connection pads 60B and 60C to the area of ​​the reference connection pad 60A is set to 1.3 or more (preferably 1.5 or more).

[0096] This eliminates the risk of the error falling within the range of manufacturing tolerances, and the temperature uniformity on the holding surface 11 can be reliably improved.

[0097] The vias 50B and 50C and the reference via 50A, as well as the connection pads 60B and 60C and the reference connection pad 60A, are connected to the chuck electrode 40.

[0098] Here, the chuck electrode 40 is often the internal electrode to which a large voltage is applied. Therefore, the vias 50 and connection pads 60 connected to the chuck electrode 40 generate a large amount of heat, which tends to increase the temperature difference at the positions of the vias 50 and connection pads 60 on the holding surface 11. Therefore, by changing the areas of the vias 50 and connection pads 60 connected to the chuck electrode 40 to which a large voltage is applied, the effect on the temperature distribution on the holding surface 11 can be minimized. Therefore, the thermal uniformity on the holding surface 11 can be improved.

[0099] <Second Example> Next, a second embodiment will be described.

[0100] In the first embodiment, attention was focused on the fact that the amount of heat drawn by the refrigerant flowing through the refrigerant flow path 23 differs between vias 50 and connection pads 60 that do not have a refrigerant flow path 23 directly below them and vias 50 and connection pads 60 that have a refrigerant flow path 23 directly below them.

[0101] Here, the portion of the lower surface 12 of the plate-like member 10 where the space 13 is located is not in contact with the bonding layer 30 and is not in contact with the base member 20 via the bonding layer 30, and therefore heat is less likely to be drawn by the refrigerant flowing through the refrigerant flow path 23. Therefore, the amount of heat drawn by the refrigerant flowing through the refrigerant flow path 23 differs between the vias 50 and connection pads 60 that are not directly below the space 13 and the vias 50 and connection pads 60 that are directly below the space 13. In other words, heat is less likely to be drawn from the vias 50 and connection pads 60 that are directly below the space 13 than from the vias 50 and connection pads 60 that are not directly below the space 13.

[0102] Therefore, a temperature difference occurs on the holding surface 11 between the positions of the vias 50 and the connection pads 60 that are not directly below the space 13 and the positions of the vias 50 and the connection pads 60 that are directly below the space 13. That is, the positions of the vias 50 and the connection pads 60 that are not directly below the space 13 receive a larger amount of heat from the refrigerant flowing through the refrigerant flow path 23, and therefore have a lower temperature than the positions of the vias 50 and the connection pads 60 that are directly below the space 13.

[0103] In particular, if the amount of heat drawn differs as described above for multiple vias 50 and connection pads 60 that are connected to the same internal electrode (e.g., chuck electrode 40) and arranged at the same height from the holding surface 11, a significant temperature difference occurs between the positions on the holding surface 11 where the vias 50 and connection pads 60 are not directly below the space 13 and the positions on the holding surface 11 where the vias 50 and connection pads 60 are directly below the space 13. Therefore, the temperature distribution on the holding surface 11 cannot be made uniform, and the thermal uniformity on the holding surface 11 decreases.

[0104] The vias 50 and connection pads 60 that are not directly below the space 13 refer to the vias 50 and connection pads 60 that are arranged at positions that do not overlap the space 13 when viewed in the thickness direction (i.e., when the electrostatic chuck 1 is viewed from the Z-axis direction). The vias 50 and connection pads 60 that are directly below the space 13 refer to the vias 50 and connection pads 60 that are arranged at positions that overlap the space 13 when viewed in the thickness direction. The vias 50 that are not directly below the space 13 are connected to one of the multiple connection pads 60, and the vias 50 that are directly below the space 13 are connected to another one of the multiple connection pads 60.

[0105] Therefore, in this embodiment, for the vias 50 among the plurality of vias 50 that are arranged at the same height position from the holding surface 11 and have the same purpose, i.e., the vias 50 that are connected to the same internal electrode (e.g., the chuck electrode 40), the area S (i.e., the area as viewed in the thickness direction) of the vias 50 that do not have the space portion 13 directly below is made different from the area S of the vias 50 that have the space portion 13 directly below. In other words, the area S of the vias 50 that have the space portion 13 directly below is made larger than the area S of the vias 50 that do not have the space portion 13 directly below.

[0106] In this way, by making the area S of the vias 50 directly below which the space 13 is located larger than the area S of the vias 50 not directly below which the space 13 is located, the vias 50 directly below which the space 13 is located generate less heat than the vias 50 not directly below which the space 13 is located. However, the vias 50 directly below which the space 13 is located attract less heat by the refrigerant flowing through the refrigerant flow path 23 than the vias 50 not directly below which the space 13 is located. Therefore, on the holding surface 11, a temperature difference is less likely to occur between the positions of the vias 50 not directly below which the space 13 is located and the positions of the vias 50 directly below which the space 13 is located, and it is possible to prevent the occurrence of temperature singularities.

[0107] The via 50 that does not have the space 13 directly below it is an example of the "third via" of the present disclosure, and the via 50 that has the space 13 directly below it is an example of the "fourth via" of the present disclosure.

[0108] In addition, in this embodiment, as another method, among the multiple connection pads 60, for the connection pads 60 that are arranged at the same height position from the holding surface 11 and have the same purpose, i.e., the connection pads 60 that are connected to the same internal electrode (e.g., the chuck electrode 40), the area of ​​the connection pads 60 that are not directly below the space 13 may be made different from the area of ​​the connection pads 60 that are directly below the space 13. In other words, the area of ​​the connection pads 60 that are directly below the space 13 may be made larger than the area of ​​the connection pads 60 that are not directly below the space 13.

[0109] In this way, by making the area of ​​the connection pads 60 directly below which the space 13 is located larger than the area of ​​the connection pads 60 not directly below which the space 13 is located, the connection pads 60 directly below which the space 13 is located generate less heat than the connection pads 60 not directly below which the space 13 is located. However, the connection pads 60 directly below which the space 13 is located attract less heat by the refrigerant flowing through the refrigerant flow path 23 than the connection pads 60 not directly below which the space 13 is located. Therefore, on the holding surface 11, a temperature difference is less likely to occur between the positions of the connection pads 60 not directly below which the space 13 is located and the positions of the connection pads 60 directly below which the space 13 is located, and it is possible to prevent the occurrence of temperature singularities.

[0110] Note that a connection pad 60 that does not have a space 13 directly below it is an example of a "third connection pad" in the present disclosure, and a connection pad 60 that has a space 13 directly below it is an example of a "fourth connection pad" in the present disclosure.

[0111] Therefore, the contents of specific examples will be described below.

[0112] In this embodiment, the via 50 and the connection pad 60 that do not have the space 13 directly below are set as the reference via 50A and the reference connection pad 60A.

[0113] [Proposal 1: When there is a coolant flow path directly below the reference via and reference connection pad] First, as a first proposal, we will explain the case where a refrigerant flow path 23 is located directly below the reference via 50A and the reference connection pad 60A, as shown in (a) of Figure 12 and "a" of Figure 13, that is, the via 50 and connection pad 60 that are not directly below the space portion 13 but have a refrigerant flow path 23 located directly below them are used as the reference via 50A and the reference connection pad 60A.

[0114] In this case, as shown in Figure 12(b) and "b" in Figure 13, as a comparative example, let us assume that the vias 50C and connection pads 60C directly below the space portion 13 and the refrigerant flow path 23 are set to the same specifications as the reference vias 50A and the reference connection pads 60A. That is, let us assume that the area of ​​the connection pads 60C is set to the same area as the reference connection pads 60A, the area S1 of one via 50C is set to the same area S1 of one reference via 50A, and the number of vias 50C is set to the same number as the number of reference vias 50A. In this case, as shown in Figure 12(b), temperature singularities occur on the holding surface 11 at the positions where the vias 50C and connection pads 60C are arranged.

[0115] Therefore, in this embodiment, the area S of the via 50C directly below which the space 13 is located is made larger than the area S of the reference via 50A directly below which the space 13 is not located. Alternatively, the area of ​​the connection pad 60C directly below which the space 13 is located is made larger than the area of ​​the reference connection pad 60A directly below which the space 13 is not located.

[0116] Specifically, as shown in (b) of Figure 14 and "b" of Figure 15, the number of vias 50C directly below which the space 13 is located is increased compared to the number of reference vias 50A that are not directly below which the space 13 is located. For example, if the number of reference vias 50A is two, the number of vias 50C is increased to three. In this case, the area of ​​the connection pad 60C is kept the same as the area of ​​the reference connection pad 60A, and the area S1 of one via 50C is kept the same as the area S1 of one reference via 50A.

[0117] In this way, the area S of the via 50C directly below the space 13 is made larger than the area S of the reference via 50A that does not have the refrigerant flow path 23 directly below it. As a result, the via 50C generates less heat than the reference via 50A, but the amount of heat drawn by the refrigerant flowing through the refrigerant flow path 23 is small. Therefore, it is possible to reduce the temperature difference on the holding surface 11 between the arrangement position of the reference via 50A and the arrangement position of the via 50C.

[0118] 14(b), it is possible to prevent temperature singularities from occurring at the positions where the vias 50C and the connection pads 60C are arranged on the holding surface 11. Therefore, it is possible to make the temperature distribution on the holding surface 11 uniform, thereby improving the thermal uniformity on the holding surface 11.

[0119] Alternatively, as another method, as shown in (c) of FIG. 14 and "c" of FIG. 15, the area S1 of one via 50C may be made larger than the area S1 of one reference via 50A. That is, the diameter of the via 50C may be made larger than the diameter of the reference via 50A so that the diameter of the reference via 50A and the diameter of the via 50C are different. In this case, the area of ​​the connection pad 60C is made the same as the area of ​​the reference connection pad 60A, and the number of vias 50C is made the same as the number of reference vias 50A. This also makes it possible to prevent temperature singularities from occurring at the positions of the vias 50C and the connection pads 60C on the support surface 11, as shown in (c) of FIG. 14.

[0120] Furthermore, as another method, the area of ​​the connection pad 60C may be made larger than the area of ​​the reference connection pad 60A, as shown in (d) of Figure 14 and "d" of Figure 15. In this case, the area S1 of one via 50C is made the same as the area S1 of one reference via 50A, and the number of vias 50C is made the same as the number of reference vias 50A. This also makes it possible to prevent temperature singularities from occurring at the positions of the vias 50C and the connection pads 60C on the support surface 11, as shown in (d) of Figure 14.

[0121] In this way, in this embodiment, the area S of the via 50C that has the space 13 directly below it is made larger than the area S of the reference via 50A that does not have the space 13 directly below it, and in this case, for example, the ratio of the area S of the via 50C to the area S of the reference via 50A (i.e., (area S of via 50C) / (area S of the reference via 50A)) is made to be 1.3 (preferably 1.5) or more.

[0122] Furthermore, in this embodiment, the area of ​​the connection pad 60C, which has the space 13 directly below it, is made larger than the area of ​​the reference connection pad 60A, which does not have the space 13 directly below it, and in this case, for example, the ratio of the area of ​​the connection pad 60C to the area of ​​the reference connection pad 60A (i.e., (area of ​​connection pad 60C) / (area of ​​reference connection pad 60A)) is made 1.3 (preferably 1.5) or more.

[0123] 12(c) and "c" in FIG. 13, as another comparative example, suppose that vias 50D and connection pads 60D that are not directly below the refrigerant flow path 23 but are directly below the space 13 are set to the same specifications as the reference vias 50A and reference connection pads 60A. That is, suppose that the area of ​​the connection pads 60D is set to the same area as the reference connection pads 60A, the area S1 of one via 50D is set to the same area S1 of one reference via 50A, and the number of vias 50D is set to the same number as the number of reference vias 50A. In this case, as shown in FIG. 12(c), temperature singularities occur on the holding surface 11 at the positions where the vias 50D and connection pads 60D are arranged.

[0124] Therefore, in this embodiment, as shown in (e) of Figure 14 and "e" of Figure 15, the number of vias 50D that have a space 13 directly below them is increased compared to the number of reference vias 50A that do not have a space 13 directly below them. For example, if the number of reference vias 50A is two, the number of vias 50D is set to three. In this case, the area of ​​the connection pad 60D is left the same as the area of ​​the reference connection pad 60A, and the area S1 of one via 50D is left the same as the area S1 of one reference via 50A.

[0125] In this way, the area S of the via 50D directly below the space 13 is made larger than the area S of the reference via 50A not directly below the space 13. As a result, the via 50D generates less heat than the reference via 50A, but the amount of heat drawn by the refrigerant flowing through the refrigerant flow path 23 is small. Therefore, it is possible to reduce the temperature difference on the holding surface 11 between the arrangement position of the reference via 50A and the arrangement position of the via 50D.

[0126] 14(e), it is possible to prevent temperature singularities from occurring at the positions where the vias 50D and the connection pads 60D are arranged on the holding surface 11. Therefore, it is possible to make the temperature distribution on the holding surface 11 uniform, thereby improving the thermal uniformity on the holding surface 11.

[0127] Alternatively, as another method, the area S1 of one via 50D may be made larger than the area S1 of one reference via 50A, as shown in (f) of Figure 14 and "f" of Figure 15. In this case, the area of ​​the connection pad 60D is made the same as the area of ​​the reference connection pad 60A, and the number of vias 50D is made the same as the number of reference vias 50A. This also makes it possible to prevent temperature singularities from occurring at the positions of the vias 50D and connection pads 60D on the support surface 11, as shown in (f) of Figure 14.

[0128] Furthermore, as another method, the area of ​​the connection pad 60D may be made larger than the area of ​​the reference connection pad 60A, as shown in (g) of Figure 14 and "g" of Figure 15. In this case, the area S1 of one via 50D is made the same as the area S1 of one reference via 50A, and the number of vias 50D is made the same as the number of reference vias 50A. This also makes it possible to prevent temperature singularities from occurring at the positions of the vias 50D and the connection pads 60D on the support surface 11, as shown in (g) of Figure 14.

[0129] [Second option: When there is no coolant flow path directly below the reference via and reference connection pad] Next, as a second proposal, we will explain the case where there is no refrigerant flow path 23 directly below the reference via 50A and the reference connection pad 60A, as shown in (a) of Figure 16 and "a" of Figure 17, i.e., the case where the via 50 and the connection pad 60 that do not have the space portion 13 and the refrigerant flow path 23 directly below them are used as the reference via 50A and the reference connection pad 60A.

[0130] In this case, as shown in (c) of Figure 16 and "c" of Figure 17, as a comparative example, a via 50D and a connection pad 60D that are not directly below the refrigerant flow path 23 but are directly below the space 13 are set to the same specifications as the reference via 50A and the reference connection pad 60A. In this case, as shown in (c) of Figure 16, a temperature singularity occurs at the arrangement position of the via 50D and the connection pad 60D on the holding surface 11.

[0131] Therefore, in this embodiment, as shown in (c) of Figure 18 and "c" of Figure 19, the number of vias 50D that have a space portion 13 directly below them is increased compared to the number of standard vias 50A that do not have a space portion 13 directly below them.

[0132] In this way, the area S of the via 50D directly below the space 13 is made larger than the area S of the reference via 50A not directly below the space 13. As a result, the via 50D generates less heat than the reference via 50A, but because the space 13 is directly below it, the amount of heat drawn by the refrigerant flowing through the refrigerant flow path 23 is small. This reduces the temperature difference between the position of the reference via 50A and the position of the via 50D on the holding surface 11. Therefore, as shown in FIG. 18(c), it is possible to prevent temperature singularities from occurring at the positions of the via 50D and the connection pad 60D on the holding surface 11. This allows the temperature distribution on the holding surface 11 to be uniform, thereby improving the thermal uniformity on the holding surface 11.

[0133] Alternatively, as another method, the area S1 of one via 50D may be made larger than the area S1 of one reference via 50A, as shown in (d) of Figure 18 and "d" of Figure 19. This also makes it possible to prevent temperature singularities from occurring at the positions of the vias 50D and the connection pads 60D on the holding surface 11, as shown in (d) of Figure 18.

[0134] Furthermore, as another method, the area of ​​the connection pad 60D may be made larger than the area of ​​the reference connection pad 60A, as shown in (e) of Figure 18 and "e" of Figure 19. This also makes it possible to prevent temperature singularities from occurring at the positions of the vias 50D and the connection pads 60D on the holding surface 11, as shown in (e) of Figure 18.

[0135] 16(b) and "b" in FIG. 17, as another comparative example, the via 50C and the connection pad 60C are assumed to have the same specifications as the reference via 50A and the reference connection pad 60A. In this case, as shown in FIG. 16(b), no temperature singularity occurs at the arrangement positions of the via 50C and the connection pad 60C on the holding surface 11. Therefore, in this embodiment, the via 50C and the connection pad 60C are assumed to have the same specifications as the reference via 50A and the reference connection pad 60A.

[0136] In this way, in this embodiment, the area S of the via 50D that has the space 13 directly below it is made larger than the area S of the reference via 50A that does not have the space 13 directly below it, for example, so that the ratio of the area S of the via 50D to the area S of the reference via 50A (i.e., (area S of the via 50D) / (area S of the reference via 50A)) is 1.3 (preferably 1.5) or more.

[0137] Furthermore, in this embodiment, the area of ​​the connection pad 60D that has the space 13 directly below it is made larger than the area of ​​the reference connection pad 60A that does not have the space 13 directly below it, for example, so that the ratio of the area of ​​the connection pad 60D to the area of ​​the reference connection pad 60A (i.e., (area of ​​the connection pad 60D) / (area of ​​the reference connection pad 60A)) is 1.3 (preferably 1.5) or more.

[0138] [Effects of this Example] According to this embodiment, the area S of the reference via 50A, which does not have the space 13 directly below it, is made different from the area S of the vias 50C and 50D, which have the space 13 directly below them.

[0139] This makes it possible to adjust the amount of heat generated by the vias 50C and 50D and the reference via 50A. This reduces the temperature difference between the positions of the vias 50C and 50D and the position of the reference via 50A on the holding surface 11. This makes it possible to make the temperature distribution on the holding surface 11 uniform, thereby improving the temperature uniformity on the holding surface 11.

[0140] Here, if there are multiple vias 50C and multiple vias 50D, possible methods for changing the area S of the vias 50C and the vias 50D include changing the number of vias 50C and the vias 50D, or changing the diameter (thickness) of the vias 50C and the vias 50D (i.e., the area S1 of one via 50C and one via 50D).

[0141] Therefore, the number of vias 50C and 50D may be the same as the number of reference vias 50A, but the diameters of the vias 50C and 50D may be different from the diameter of the reference via 50A.

[0142] In this way, by simply changing the diameters of the vias 50C and 50D, the area S1 of one of the vias 50C and 50D can be made different from the area S1 of one reference via 50A, with almost no change to the manufacturing process of the electrostatic chuck 1. Therefore, the temperature uniformity on the holding surface 11 can be improved without increasing the manufacturing cost.

[0143] Here, if the ratio of the area S of vias 50C and 50D to the area S of the reference via 50A is less than 1.3, there is a risk that it will fall within the range of product error, and there is a risk that the thermal uniformity on the holding surface 11 will not be improved.

[0144] Therefore, in this embodiment, the ratio of the area S of the vias 50C and 50D to the area S of the reference via 50A is set to 1.3 or more (preferably 1.5 or more).

[0145] This eliminates the risk of the error falling within the range of manufacturing tolerances, and the temperature uniformity on the holding surface 11 can be reliably improved.

[0146] Furthermore, the areas of the connection pads 60C and 60D may be different from the area of ​​the reference connection pad 60A.

[0147] This makes it possible to adjust the amount of heat generated by the connection pads 60C and 60D and the reference connection pad 60A, respectively. This makes it possible to reduce the temperature difference between the positions of the connection pads 60C and 60D and the position of the reference connection pad 60A on the holding surface 11. This makes it possible to make the temperature distribution on the holding surface 11 uniform, thereby improving the temperature uniformity on the holding surface 11.

[0148] In this embodiment, the ratio of the area of ​​the connection pads 60C and 60D to the area of ​​the reference connection pad 60A is set to 1.3 or more (preferably 1.5 or more).

[0149] This eliminates the risk of the error falling within the range of manufacturing tolerances, and the temperature uniformity on the holding surface 11 can be reliably improved.

[0150] The vias 50C and 50D and the reference via 50A, as well as the connection pads 60C and 60D and the reference connection pads 60A, are connected to the chuck electrode 40.

[0151] Here, the chuck electrode 40 is often the internal electrode to which a large voltage is applied. Therefore, the vias 50 and connection pads 60 connected to the chuck electrode 40 generate a large amount of heat, which tends to increase the temperature difference at the positions of the vias 50 and connection pads 60 on the holding surface 11. Therefore, by changing the areas of the vias 50 and connection pads 60 connected to the chuck electrode 40 to which a large voltage is applied, the effect on the temperature distribution on the holding surface 11 can be minimized. Therefore, the thermal uniformity on the holding surface 11 can be improved.

[0152] It should be noted that the above-described embodiments are merely examples and do not limit the present disclosure in any way. It goes without saying that various improvements and modifications are possible within the scope of the gist of the present disclosure.

[0153] For example, the plate-shaped member 10 has heater electrodes and other electrodes in addition to the chuck electrode 40 as internal electrodes. The content of the present disclosure, i.e., changing the area of ​​the via 50 or the connection pad 60, can also be applied to heater electrodes and other electrodes other than the chuck electrode 40. In this case, the priority for changing the area of ​​the via 50 or the connection pad 60 is set higher for internal electrodes that are more likely to generate a large amount of heat due to a larger applied voltage. For example, the priority for changing the area of ​​the via 50 or the connection pad 60 is set higher for the chuck electrode 40, which is applied with a larger voltage, than for the heater electrodes and other electrodes.

[0154] Furthermore, although the space 13 is formed on the lower surface 12 of the plate-shaped member 10 so as to be recessed toward the holding surface 11, this is not limiting. That is, the space 13 may be disposed inside the plate-shaped member 10 (more specifically, in a position inside the plate-shaped member 10 between the via 50 or the connection pad 60 and the lower surface 12) without being exposed to the lower surface 12. In this case, for example, the space 13 is a gas path for flowing gas on the surface of the plate-shaped member 10. [Explanation of symbols]

[0155] 1. Electrostatic chuck 10 Plate-shaped member 11 Holding surface 12 Bottom side 13 Space section 20 Base member 23 Refrigerant flow path 30 Bonding layer 40 Chuck electrode 50 Beer 50A standard via 50B (There is no space directly below, but the coolant flow path is directly below) via 50C (Space and coolant flow path directly below) via 50D (There is no coolant flow path directly below, but there is a space directly below) via 60 connection pads 60A standard connection pad 60B (There is no space directly below, but there is a coolant flow path directly below) Connection pad 60C (Space and coolant flow path directly below) Connection pad 60D (There is no coolant flow path directly below, but there is a space directly below) Connection pad W Semiconductor wafer S (total area of ​​all vias connected to one connection pad) Area S1 Area (of one via)

Claims

1. a plate-like member having a first surface and a second surface provided on the opposite side of the first surface in a thickness direction; a refrigerant flow path for flowing a refrigerant, A holding device for holding an object on the first surface, an internal electrode, a plurality of vias for supplying power to the internal electrode, a plurality of connection pads, and a space are arranged inside the plate-like member; Among the plurality of vias, the vias that are arranged at the same height position from the first surface and connected to the internal electrodes include a first via that is disposed at a position that does not overlap the coolant flow path when viewed in the thickness direction and is connected to one of the connection pads; a second via that is arranged at a position overlapping the coolant flow path when viewed in the thickness direction and is connected to another one of the connection pads; Contains an area of ​​the first via as viewed in the thickness direction is different from an area of ​​the second via as viewed in the thickness direction; Or, Among the plurality of vias, the vias that are arranged at the same height position from the first surface and connected to the internal electrodes include a third via that is disposed at a position that does not overlap the space portion when viewed in the thickness direction and is connected to one of the connection pads; a fourth via that is arranged at a position that overlaps with the space portion when viewed in the thickness direction and is connected to another one of the connection pads; Contains an area of ​​the third via as viewed in the thickness direction is different from an area of ​​the fourth via as viewed in the thickness direction; A holding device characterized by:

2. a plate-like member having a first surface and a second surface provided on the opposite side of the first surface in a thickness direction; a refrigerant flow path for flowing a refrigerant, A holding device for holding an object on the first surface, an internal electrode, a plurality of vias for supplying power to the internal electrode, a plurality of connection pads, and a space are arranged inside the plate-like member; Among the plurality of connection pads, the connection pads that are arranged at the same height from the first surface and are connected to the internal electrodes include a first connection pad disposed at a position not overlapping the refrigerant flow path when viewed in the thickness direction; a second connection pad disposed at a position overlapping the refrigerant flow path when viewed in the thickness direction; Contains an area of ​​the first connection pad as viewed in the thickness direction is different from an area of ​​the second connection pad as viewed in the thickness direction; Or, Among the plurality of connection pads, the connection pads that are arranged at the same height from the first surface and are connected to the internal electrodes include a third connection pad disposed at a position not overlapping the space portion when viewed in the thickness direction; a fourth connection pad arranged at a position overlapping the space portion when viewed in the thickness direction; Contains an area of ​​the third connection pad as viewed in the thickness direction is different from an area of ​​the fourth connection pad as viewed in the thickness direction; A holding device characterized by:

3. 2. The holding device according to claim 1, the number of the first vias and the number of the second vias are the same; the first via and the second via each have a circular shape when viewed in the thickness direction, the first via and the second via have different diameters as viewed in the thickness direction; Or, the number of the third vias and the number of the fourth vias are the same; the third via and the fourth via each have a circular shape when viewed in the thickness direction, the third via and the fourth via have different diameters as viewed in the thickness direction; A holding device characterized by:

4. The holding device according to any one of claims 1 to 3, the internal electrode is a chuck electrode; A holding device characterized by:

5. The holding device according to any one of claims 1 to 3, a ratio of an area of ​​the first via as viewed in the thickness direction to an area of ​​the second via as viewed in the thickness direction is 1.3 or more; or a ratio of an area of ​​the first connection pad as viewed in the thickness direction to an area of ​​the second connection pad as viewed in the thickness direction is 1.3 or more; Or, a ratio of an area of ​​the third via as viewed in the thickness direction to an area of ​​the fourth via as viewed in the thickness direction is 1.3 or more; or a ratio of an area of ​​the third connection pad as viewed in the thickness direction to an area of ​​the fourth connection pad as viewed in the thickness direction is 1.3 or more; A holding device characterized by:

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