Holding device and electrostatic chuck

Abstract

A technique is provided that can reduce the thermal resistance of a bonding layer. [Solution] The holding device is characterized by satisfying at least one of the following conditions (A) to (C). Condition (A): The holding device includes a filler in contact with the holding member or the base member. Condition (B): When the proportions of the total cross-sectional area of ​​the filler in the bonding layer within a range of 1 μm or less from the interface with the holding member and the interface with the base member are defined as a first proportion and a second proportion, and the proportion of the total cross-sectional area of ​​the filler in the bonding layer within a range of 30% or less of the thickness of the bonding layer from the center in the thickness direction of the bonding layer to the holding member side and the base member side are defined as a third proportion, at least one of the values ​​obtained by dividing the first proportion by the third proportion and the value obtained by dividing the second proportion by the third proportion is 0.5 or more. Condition (C): Among the fillers, the amount of fillers having an aspect ratio of 1.4 or more is greater than the amount of fillers having an aspect ratio of less than 1.4.

Description

[Technical field]

[0001] The present invention relates to a holding device and an electrostatic chuck. [Background technology]

[0002] A holding member that holds an object by electrostatic attraction is known. For example, Patent Document 1 discloses an electrostatic chuck including such a holding member, a base member, and a bonding layer that bonds the holding member and the base member. The bonding layer includes a first resin layer that contains a filler and a second resin layer that does not contain a filler, and the second resin layer is disposed between the first resin layer and the holding member and between the first resin layer and the base member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6321522 Summary of the Invention [Problem to be solved by the invention]

[0004] In the electrostatic chuck described in Patent Document 1, the second resin layer, which does not contain a filler and has a lower thermal conductivity than the first resin layer, is present at the interface of the bonding layer with the holding member and the interface with the base member, increasing the thermal resistance of the bonding layer. Therefore, there is room for improvement in reducing the thermal resistance of the bonding layer.

[0005] The present invention has been made to solve at least part of the above-mentioned problems, and has an object to provide a technique capable of reducing the thermal resistance of a bonding layer. [Means for solving the problem]

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following forms. (1) According to one aspect of the present invention, there is provided a holding device comprising: a holding member having a holding surface for holding an object, a base member disposed on the holding member opposite to the holding surface, and a bonding layer bonding the holding member and the base member and including a plurality of fillers, the holding device being characterized in that it satisfies at least one of the following conditions (A) to (C): Condition (A): The filler includes at least one of a first filler in contact with the holding member and a second filler in contact with the base member. Condition (B): When a first ratio is a ratio of the total cross-sectional area of ​​the filler in the bonding layer within a range of 1 μm or less from the interface with the holding member, a second ratio is a ratio of the total cross-sectional area of ​​the filler in the bonding layer within a range of 1 μm or less from the interface with the base member, and a third ratio is a ratio of the total cross-sectional area of ​​the filler in the bonding layer within a range of 30% or less of the thickness of the bonding layer from the center in the thickness direction of the bonding layer to the holding member side and within a range of 30% or less of the thickness of the bonding layer from the center to the base member side, at least one of the values ​​obtained by dividing the first ratio by the third ratio and the second ratio by the third ratio is 0.5 or more. Condition (C): Among the fillers, the amount of the fillers having an aspect ratio of 1.4 or more is greater than the amount of the fillers having an aspect ratio of less than 1.4.

[0007] According to this configuration, the holding device satisfies at least one of the conditions (A) to (C). When the condition (A) is satisfied, since the filler having a relatively high thermal conductivity is in contact with at least one of the holding member and the base member, the thermal resistance at at least one of the interface between the bonding layer and the holding member and the interface between the bonding layer and the base member can be reduced. When the condition (B) is satisfied, since at least one of the range of the bonding layer that is 1 μm or less from the interface with the holding member and the range of the bonding layer that is 1 μm or less from the interface with the base member is contained in a relatively large amount of filler, the thermal resistance at at least one of the vicinity of the interface with the holding member and the vicinity of the interface with the base member can be reduced. When the condition (C) is satisfied, since the filler having an aspect ratio of 1.4 or more is more than the filler having an aspect ratio of less than 1.4 in the bonding layer, heat can be easily transferred in the thickness direction of the bonding layer with a small amount of filler, the thermal resistance of the bonding layer can be reduced while maintaining flexibility. In this way, by satisfying at least one of the conditions (A) to (C), the thermal resistance of the bonding layer can be reduced.

[0008] (2) In the holding device of the above form, the holding device satisfies at least the condition (A), and at least one of the first filler and the second filler contained in the bonding layer may contain a large-diameter filler having a particle size larger than the average particle size of the filler. According to this configuration, at least one of the first and second fillers contained in the bonding layer contains a large-diameter filler, which makes it easier to transfer heat from the interface in the thickness direction of the bonding layer, thereby further reducing the thermal resistance of the interface.

[0009] (3) In the holding device of the above form, the holding device satisfies at least the condition (A), and at least one of the first filler and the second filler contained in the bonding layer may contain a small diameter filler having a particle size smaller than the average particle size. According to this configuration, at least one of the first filler and the second filler contained in the bonding layer contains small diameter fillers in addition to large diameter fillers, and since a large number of fillers are in contact with the holding member or the base member, it is possible to more easily transmit heat from the interface in the thickness direction of the bonding layer.

[0010] (4) In the holding device of the above form, the holding device satisfies at least the condition (A), and in at least one of the first filler and the second filler contained in the bonding layer, the sum of the cross-sectional areas of the large diameter fillers may be greater than the sum of the cross-sectional areas of the small diameter fillers. According to this configuration, in at least one of the first and second fillers contained in the bonding layer, the amount of large diameter filler is guaranteed to a certain extent relative to the amount of small diameter filler, thereby ensuring the effect of the large diameter filler in reducing the thermal resistance at the interface.

[0011] (5) In the holding device of the above embodiment, the holding device satisfies at least the condition (A), and at least one of the first filler and the second filler contained in the bonding layer may include a filler having an aspect ratio of 1.4 or more. According to this configuration, at least one of the first and second fillers contained in the bonding layer contains a filler having an aspect ratio of 1.4 or more, which makes it easier to transfer heat from the interface in the thickness direction of the bonding layer, thereby further reducing the thermal resistance of the interface.

[0012] (6) In the holding device of the above embodiment, the holding device satisfies at least the condition (A), and at least one of the first filler and the second filler contained in the bonding layer may include a filler having an aspect ratio of less than 1.4. According to this configuration, at least one of the first filler and the second filler contained in the bonding layer contains fillers with an aspect ratio of less than 1.4 in addition to fillers with an aspect ratio of 1.4 or more. Therefore, since a large number of fillers are in contact with the holding member or the base member, it is possible to more easily transfer heat from the interface in the thickness direction of the bonding layer.

[0013] (7) In the holding device of the above form, the holding device satisfies at least the condition (A), and in at least one of the first filler and the second filler contained in the bonding layer, the sum of the cross-sectional areas of the fillers having an aspect ratio of 1.4 or more may be greater than the sum of the cross-sectional areas of the fillers having an aspect ratio of less than 1.4. According to this configuration, in at least one of the first filler and the second filler contained in the bonding layer, the amount of filler having an aspect ratio of 1.4 or more is guaranteed to be greater than the amount of filler having an aspect ratio of less than 1.4, thereby ensuring a reduction in the thermal resistance of the interface due to the filler having an aspect ratio of 1.4 or more.

[0014] (8) In the holding device of the above form, the holding device satisfies at least the condition (A), and at least one of the portion of the holding member joined to the bonding layer and the portion of the base member joined to the bonding layer has a recess that is deeper than the average grain size, the depth of the recess is greater than the average grain size of the filler, and the recess is filled with the bonding layer, and a large-diameter filler having a grain size larger than the average grain size of the filler is in contact with a surface defining the recess. According to this configuration, the formation of the recess leads to an increase in the surface area, so that it is possible to reduce the thermal resistance of at least one of the interface between the holding member and the bonding layer and the interface between the base member and the bonding layer. In addition, since the surface defining the recess is in contact with large-diameter filler particles having a particle size larger than the average particle size of the filler, it is possible to further reduce the thermal resistance of the interface.

[0015] (9) In the holding device of the above form, the holding device satisfies at least the condition (A), and at least one of the portion of the holding member joined to the bonding layer and the portion of the base member joined to the bonding layer has a recess that is deeper than the average grain size, the depth of the recess is greater than the average grain size of the filler, and the recess is filled with the bonding layer, and the filler having an aspect ratio of 1.4 or more is in contact with a surface defining the recess. According to this configuration, the formation of the recess leads to an increase in the surface area, so that the thermal resistance of at least one of the interface between the holding member and the bonding layer and the interface between the base member and the bonding layer can be reduced. In addition, since the surface defining the recess is in contact with a filler having an aspect ratio of 1.4 or more, the thermal resistance of the interface can be further reduced.

[0016] (10) According to another aspect of the present invention, there is provided an electrostatic chuck comprising: a holding device according to any one of claims 1 to 9; and an electrostatic electrode that generates an electrostatic attractive force on the holding surface. According to this configuration, when power is supplied to the electrostatic electrode, an electrostatic attraction (adsorption force) is generated, and the object can be held on the holding surface side by this electrostatic attraction. In addition, since the holding device satisfies at least one of the conditions (A) to (C), it is possible to provide an electrostatic chuck with reduced thermal resistance of the bonding layer.

[0017] The present invention can be realized in various forms, for example, in the form of a holding member, an electrostatic chuck equipped with an electrostatic electrode that generates electrostatic attraction on the holding member and the holding surface of the holding member, a vacuum chuck, a ceramic heater, semiconductor manufacturing equipment, parts equipped with these, and methods of manufacturing these, etc. [Brief description of the drawings]

[0018] [Figure 1]FIG. 1 is an explanatory diagram illustrating a cross-sectional configuration of an electrostatic chuck according to a first embodiment. [Diagram 2] FIG. 4 is an enlarged view showing a cross-sectional configuration of a bonding layer. [Diagram 3] FIG. 2 is an explanatory diagram in which each filler is partially hatched. [Figure 4] 4 is an explanatory diagram showing each range in a cross-sectional configuration of a bonding layer. FIG. [Diagram 5] FIG. 11 is an enlarged view showing a cross-sectional configuration of a holding device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] First Embodiment FIG. 1 is an explanatory diagram showing a schematic cross-sectional configuration of an electrostatic chuck 1 according to a first embodiment. The electrostatic chuck 1 is a device that attracts and holds a semiconductor wafer W, which is an object, by electrostatic attraction. The arrow shown in FIG. 1 indicates the direction in which the semiconductor wafer W is attracted to the electrostatic chuck 1. The electrostatic chuck 1 is used, for example, to fix the semiconductor wafer W in a vacuum chamber of a semiconductor manufacturing device. The electrostatic chuck 1 includes a holding member 10, a base member 20, and a bonding layer 30. Among the members that constitute the electrostatic chuck 1, the holding member 10, the base member 20, and the bonding layer 30 are collectively referred to as a holding device H.

[0020] The holding member 10 is a disk-shaped member that holds the semiconductor wafer W as an object, and is made of alumina, aluminum nitride, or the like. The holding member 10 has a holding surface 10f. The holding surface 10f is a circular surface on the side that holds the semiconductor wafer W.

[0021] The electrostatic electrode 12 is disposed inside the holding member 10. The electrostatic electrode 12 is a disk-shaped member, and is made of a conductive material such as tungsten or molybdenum. The via 14 is connected to the electrostatic electrode 12 inside the holding member 10. The via 14 is a rod-shaped member, and is made of the same material as the electrostatic electrode 12.

[0022] The base member 20 is a disk-shaped member arranged on the side of the holding member 10 opposite to the holding surface 10f, and is made of aluminum, an aluminum alloy, or the like. A coolant flow path 22 is arranged inside the base member 20. The coolant flow path 22 is a flow path through which a cooling medium (e.g., a fluorinated liquid, pure water, etc.) flows.

[0023] The bonding layer 30 is a resin layer R (illustrated in FIG. 2 and subsequent figures) that is disposed between the holding member 10 and the base member 20 and bonds the holding member 10 and the base member 20, and contains a plurality of fillers F (illustrated in FIG. 2 and subsequent figures). Details will be described later.

[0024] A through hole 40 is formed inside the electrostatic chuck 1, penetrating the base member 20 and the bonding layer 30 to the inside of the holding member 10. A cylindrical insulating member 42 is fitted into the through hole 40. A metallized layer 44 connected to the via 14 is disposed on the bottom surface of the through hole 40 located inside the holding member 10. The metallized layer 44 is a plate-shaped member and is formed of the same material as the electrostatic electrode 12 and the via 14. The connection terminal 46 is connected to the metallized layer 44 and to a terminal fitting 48. An external power source (not shown) is connected to the terminal fitting 48. That is, the electrostatic electrode 12 generates an electrostatic attraction force on the holding surface 10f by supplying power from an external power source (not shown) through the via 14, the metallized layer 44, the connection terminal 46, and the terminal fitting 48. The semiconductor wafer W is attracted toward the holding surface 10f by this electrostatic attraction force, and is held on the holding surface 10f.

[0025] 2 is an enlarged view of a cross-sectional configuration of the bonding layer 30. As described above, the bonding layer 30 is a resin layer R containing a plurality of fillers F. In FIG. 2, the portion of the bonding layer 30 other than the fillers F shows the resin layer R. The thermal conductivity of the fillers F is higher than the thermal conductivity of the resin layer R. The holding device H (holding member 10, base member 20, and bonding layer 30) satisfies the following condition (A). Condition (A): The plurality of fillers F include at least one of a first filler F1 in contact with the holding member 10 and a second filler F2 in contact with the base member 20. When each portion of the bonding layer 30 is photographed with a scanning electron microscope (SEM), if even one portion that satisfies the condition (A) can be photographed, the bonding layer 30 is deemed to satisfy the condition (A).

[0026] Regarding condition (A), in this embodiment, the multiple fillers F contained in the bonding layer 30 include both a first filler F1 in contact with the holding member 10 and a second filler F2 in contact with the base member 20. Here, when even a part of the filler F is contained within a range R1 of 0.5 μm or less from an interface BD1 between the holding member 10 and the bonding layer 30, or within a range R2 of 0.5 μm or less from an interface BD2 between the base member 20 and the bonding layer 30, such filler F is defined as a first filler F1 or a second filler F2.

[0027] The first filler F1 includes first fillers F1a, F1b, and F1c, which are large-diameter fillers having a particle size larger than the average particle size of the filler F. The second filler F2 also includes second fillers F2a, F2c, F2e, and F2g, which are large-diameter fillers having a particle size larger than the average particle size of the filler F. Furthermore, in this embodiment, each of the first filler F1 and the second filler F2 also includes first filler F1d and second fillers F2b, F2d, and F2f, which are small-diameter fillers having a particle size smaller than the average particle size of the filler F. Here, the average particle size is determined by binarizing a cross-sectional image of the bonding layer 30 photographed by an SEM and then calculating the area of ​​each filler F to be a perfect circle (πr 2 ), and then the diameter (2r) is regarded as the particle size of each filler F, the average particle size corresponds to the median diameter of the particle sizes. More specifically, a cross-sectional image of the bonding layer 30 captured so as to include at least 500 or more fillers F is used, and the median diameter of the particle sizes of all the fillers F captured in the cross-sectional image corresponds to the average particle size.

[0028] FIG. 3 is an explanatory diagram in which each of the first filler F1 and the second filler F2 shown in FIG. 2 is partially hatched. The sum of the cross-sectional areas of the large-diameter fillers in the first filler F1 is greater than the sum of the cross-sectional areas of the small-diameter fillers. In other words, the sum of the cross-sectional areas of the first fillers F1 having a particle size larger than the average particle size is greater than the sum of the cross-sectional areas of the first fillers F1 having a particle size smaller than the average particle size. Here, the sum of the cross-sectional areas of the large-diameter fillers (the first fillers F1 having a particle size larger than the average particle size) in the first filler F1, when explained with reference to FIG. 3, does not mean the sum of the cross-sectional areas of the parts included in the range R1 among the first fillers F1a, F1b, and F1c, but the sum of the entire cross-sectional area (shown by hatching in the first fillers F1a, F1b, and F1c in FIG. 3). Similarly, the sum of the cross-sectional areas of the small diameter fillers (first fillers F1 having a particle size larger than the average particle size) among the first fillers F1, as explained with reference to Figure 3, does not refer to the sum of the cross-sectional areas of the portions of the first filler F1d included in the range R2, but refers to the overall cross-sectional area (shown by hatching in the first filler F1d in Figure 3).

[0029] Similarly to the first filler F1, the sum of the cross-sectional areas of the large-diameter fillers in the second filler F2 is greater than the sum of the cross-sectional areas of the small-diameter fillers. Explained with reference to Fig. 3, the sum of the total cross-sectional areas of the second fillers F2a, F2c, F2e, and F2g (shown by hatching in the second fillers F2a, F2c, F2e, and F2g in Fig. 3) is greater than the total cross-sectional area of ​​the second fillers F2b, F2d, and F2f (shown by hatching in the second fillers F2b, F2d, and F2f in Fig. 3).

[0030] In addition to the above condition (A), the holding device H also satisfies the following condition (B). Note that the range Rg1, range Rg2, center O, range Ro1, and range Ro2 in the following condition (B) are shown in FIG. 4. Condition (B): When the ratio of the total cross-sectional area of ​​filler F in the bonding layer 30 within a range Rg1 that is 1 μm or less from the interface BD1 with the holding member 10 is defined as a first ratio, the ratio of the total cross-sectional area of ​​filler F in the bonding layer 30 within a range Rg2 that is 1 μm or less from the interface BD2 with the base member 20 is defined as a second ratio, and the ratio of the total cross-sectional area of ​​filler F in the bonding layer 30 within a range Ro1 that is 30% or less of the thickness of the bonding layer 30 from the center O to the holding member 10 side in the thickness direction of the bonding layer 30 and within a range Ro2 that is 30% or less of the thickness of the bonding layer 30 from the center O to the base member 20 side in the thickness direction of the bonding layer 30 is defined as a third ratio, at least one of the values ​​obtained by dividing the first ratio by the third ratio and the values ​​obtained by dividing the second ratio by the third ratio is 0.5 or more. When each portion of the bonding layer 30 is photographed by SEM, if even one portion that satisfies condition (B) can be photographed, the bonding layer 30 is deemed to satisfy condition (B). In this case, the value obtained by dividing the first ratio by the third ratio and the value obtained by dividing the second ratio by the third ratio, which are the criteria for determining whether or not condition (B) is satisfied, are values ​​calculated using the first to third ratios calculated within the same cross-sectional image.

[0031] In the condition (B), in this embodiment, both the value obtained by dividing the first ratio by the third ratio and the value obtained by dividing the second ratio by the third ratio are 0.5 or more. Here, the ratio (first ratio) of the total cross-sectional area of ​​the filler F in the range Rg1 refers to the ratio of the total cross-sectional area of ​​the first fillers F1a to F1d included in the range Rg1 (shown by hatching in the first fillers F1a to F1d in FIG. 4) to the cross-sectional area of ​​the range Rg1. Similarly, the ratio of the total cross-sectional area of ​​the filler F in the range Rg2 refers to the total area of ​​the second fillers F2a to F2g included in the range Rg2 (shown by hatching in the second fillers F2a to F2g in FIG. 4) to the cross-sectional area of ​​the range Rg2.

[0032] The ratio (third ratio) of the sum of the cross-sectional areas of filler F in ranges Ro1 and Ro2 refers to the ratio of the sum of the cross-sectional areas of the portions of each filler F included in ranges Ro1 and Ro2 (shown by hatching in filler F within ranges Ro1 and Ro2 in Figure 4) to the sum of the cross-sectional areas of ranges Ro1 and Ro2.

[0033] In addition to the above conditions (A) and (B), the holding device H also satisfies the following condition (C). The aspect ratio of each filler F is determined by binarizing a cross-sectional image of the bonding layer 30 taken by SEM, fitting each filler F to an ellipse by the least squares method, and then dividing the major axis of the ellipse by the minor axis. Condition (C): Among the fillers F, the amount of fillers F having an aspect ratio of 1.4 or more is greater than the amount of fillers F having an aspect ratio of less than 1.4. When each portion of the bonding layer 30 is photographed by SEM, if at least one portion that satisfies condition (C) is photographed, the bonding layer 30 is deemed to satisfy condition (C). More specifically, if at least one cross-sectional image that satisfies condition (C) is confirmed among cross-sectional images of the bonding layer 30 photographed so as to contain at least 500 or more fillers F, the bonding layer 30 is deemed to satisfy condition (C).

[0034] Regarding condition (C), in this embodiment, each of the first filler F1 (filler F in contact with the holding member 10) and the second filler F2 (filler F in contact with the base member 20) contains filler F having an aspect ratio of 1.4 or more. Each of the first filler F1 and the second filler F2 also contains filler F having an aspect ratio of less than 1.4. Furthermore, the sum of the cross-sectional areas of the fillers F having an aspect ratio of 1.4 or more among the first filler F1 is greater than the sum of the cross-sectional areas of the fillers F having an aspect ratio of less than 1.4. Similarly, the sum of the cross-sectional areas of the fillers F having an aspect ratio of 1.4 or more among the second filler F2 is greater than the sum of the cross-sectional areas of the fillers F having an aspect ratio of less than 1.4. The sum of the cross-sectional areas here does not refer to the sum of the cross-sectional areas of the portions of each filler F that are included in ranges R1 and R2, as in the case of the large diameter fillers and small diameter fillers described above, but refers to the sum of the entire cross-sectional area of ​​each filler F.

[0035] In the electrostatic chuck 1, the resin material (material that is the base of the bonding layer 30) contains more filler F having an aspect ratio of 1.4 or more than filler F having an aspect ratio of less than 1.4, so that the holding device H satisfies the condition (C). The electrostatic chuck 1 is manufactured by applying such a resin material onto the surface of the base member 20, heat-curing the resin material to form the bonding layer 30, and then placing the holding member 10 on the surface of the bonding layer 30 opposite the base member 20. In this manufacturing process, a load is applied in the thickness direction to the resin material in a semi-cured state before it is completely cured to form the bonding layer 30, so that the filler F is easily disposed at the end side in the thickness direction of the resin material (bonding layer 30) (near the interface with the holding member 10 or near the interface with the base member 20). Then, the resin material is completely cured under the load, so that the resin material becomes the bonding layer 30. By applying a load during semi-curing in this manner, it becomes easier for large-diameter fillers and fillers F with an aspect ratio of 1.4 or more to be arranged at the end side in the thickness direction of the resin material (bonding layer 30). In other words, by applying a load during semi-curing, the holding device H becomes easier to satisfy conditions (A) and (B).

[0036] As described above, the holding device H (holding member 10, base member 20, and bonding layer 30) included in the electrostatic chuck 1 of this embodiment satisfies all of the conditions (A) to (C). When condition (A) is satisfied, the first filler F1 and the second filler F2 of the filler F, which has a relatively high thermal conductivity (compared to the resin layer R), are in contact with the holding member 10 and the base member 20, and therefore it is possible to reduce the thermal resistance at both the interface BD1 (see FIGS. 2 to 4) between the bonding layer 30 and the holding member 10 and the interface BD2 (see FIGS. 2 to 4) between the bonding layer 30 and the base member 20. When the condition (B) is satisfied, a relatively large amount of filler F is contained in both the range Rg1 of 1 μm or less from the interface BD1 and the range Rg2 of 1 μm or less from the interface BD2 (first ratio / third ratio≧0.5 and second ratio / third ratio≧0.5), so that the thermal resistance in the vicinity of both interfaces, namely, the vicinity of the interface BD1 and the vicinity of the interface BD2, can be reduced. When the condition (C) is satisfied, the filler F having an aspect ratio of 1.4 or more is more than the filler F having an aspect ratio of less than 1.4 in the bonding layer 30, so that the heat can be easily transferred in the thickness direction of the bonding layer 30 with a small amount of filler F, so that the thermal resistance of the bonding layer 30 can be reduced while maintaining flexibility. In this way, the holding device H satisfies all of the conditions (A) to (C), so that the thermal resistance of the bonding layer 30 can be reduced.

[0037] In addition, in the holding device H included in this embodiment, the first filler F1 and the second filler F2 include the first fillers F1a, F1b, and F1c and the second fillers F2a, F2c, F2e, and F2g, which are large-diameter fillers having a particle size larger than the average particle size of the filler F. This makes it easier to transfer heat from the interfaces BD1 and BD2 in the thickness direction of the bonding layer 30. As a result, the thermal resistance of the interfaces BD1 and BD2 can be further reduced.

[0038] In addition, in the holding device H included in this embodiment, the first filler F1 and the second filler F2 include, in addition to the large diameter filler, the first filler F1d and the second fillers F2b, F2d, and F2f, which are small diameter fillers having a particle size smaller than the average particle size of the filler F. Therefore, since the number of fillers F in contact with the holding member 10 and the base member 20 is large, it is possible to more easily transfer heat from the interfaces BD1 and BD2 in the thickness direction of the bonding layer 30.

[0039] In addition, in the holding device H included in this embodiment, in the first filler F1, the sum of the cross-sectional areas of the large diameter fillers (corresponding to F1a, F1b, and F1c in FIG. 2) is greater than the sum of the cross-sectional areas of the small diameter fillers (corresponding to F1d in FIG. 2). In the second filler F2, the sum of the cross-sectional areas of the large diameter fillers (corresponding to F2a, F2c, F2e, and F2g in FIG. 2) is greater than the sum of the cross-sectional areas of the small diameter fillers (corresponding to F2b, F2d, and F2f in FIG. 2). Therefore, in both the first filler F1 and the second filler F2, the amount of the large diameter fillers relative to the amount of the small diameter fillers is guaranteed to a certain extent, so that the reduction effect of the thermal resistance of the interfaces BD1 and BD2 by the large diameter fillers can be guaranteed.

[0040] In addition, in the holding device H included in this embodiment, the first filler F1 and the second filler F2 include filler F having an aspect ratio of 1.4 or more. This makes it easier to transfer heat from the interfaces BD1 and BD2 in the thickness direction of the bonding layer 30. As a result, the thermal resistance of the interfaces BD1 and BD2 can be further reduced.

[0041] Furthermore, in the holding device H included in this embodiment, the first filler F1 and the second filler F2 include fillers F having an aspect ratio of less than 1.4, in addition to fillers F having an aspect ratio of 1.4 or more. Therefore, since there are a large number of fillers F in contact with the holding member 10 and the base member 20, it is possible to more easily transfer heat from the interfaces BD1 and BD2 in the thickness direction of the bonding layer 30.

[0042] Furthermore, in the retaining device H included in this embodiment, the sum of the cross-sectional areas of the fillers F having an aspect ratio of 1.4 or more is greater than the sum of the cross-sectional areas of the fillers F having an aspect ratio less than 1.4 in both the first filler F1 and the second filler F2. Therefore, since the amount of fillers having an aspect ratio of 1.4 or more relative to the amount of fillers having an aspect ratio less than 1.4 is guaranteed to a certain extent in both the first filler F1 and the second filler F2, it is possible to guarantee the effect of reducing the thermal resistance of the interfaces BD1, BD2 by the fillers having an aspect ratio of 1.4 or more.

[0043] In the electrostatic chuck 1 of the present embodiment, an electrostatic attraction force (adsorption force) is generated by supplying power to the electrostatic electrode 12, and the semiconductor wafer W can be held on the holding surface 10f side by this electrostatic attraction force. Since the electrostatic chuck 1 includes the holding device H that satisfies all of the conditions (A) to (C), it is possible to provide an electrostatic chuck 1 in which the thermal resistance of the bonding layer 30 is reduced.

[0044] <Second embodiment> FIG. 5 is an explanatory diagram showing the base member 20a and the bonding layer 30 of the holding device Ha of the second embodiment. The holding device Ha of the second embodiment is the same as the holding device H of the first embodiment, except that the holding device Ha of the second embodiment includes a base member 20a different from the base member 20 compared to the holding device H of the first embodiment. That is, the holding device Ha of the second embodiment is also configured to be included in the electrostatic chuck 1, similar to the holding device H of the first embodiment. In the description of the second embodiment, the same components as those of the first embodiment are given the same reference numerals, and the preceding description is referred to. Note that, although the base member 20 is hatched in FIGS. 1 to 4, the base member 20 is not hatched in FIG. 5 for convenience of illustration. Also, in FIG. 5, the filler F is shown as a circle for convenience of illustration.

[0045] In the portion of the base member 20a bonded to the bonding layer 30, a recess 20D is formed that is recessed deeper than the average grain size of the filler F. The recess 20D is formed by laser processing or the like. The depth DP of the recess 20D is larger than the average grain size of the filler F, and the recess 20D is filled with the bonding layer 30. Furthermore, a large-diameter filler FL having a grain size larger than the average grain size of the filler F is in contact with a surface 20DS that defines the recess 20D. Here, if even a part of the filler F is included within a range Ra of 0.5 μm or less from the surface 20DS, such a filler F is considered to be in contact with the surface 20DS. In the recess 20D, since the surface 20DS can be considered as the interface BD2, the range Rg2 (see FIG. 4) is specified as a range of 1 μm or less from the surface 20DS.

[0046] According to the holding device Ha of the second embodiment described above, similarly to the first embodiment, it is possible to reduce the thermal resistance of the bonding layer 30. Furthermore, in the holding device Ha of the second embodiment, the formation of the recessed portion 20D leads to an increase in the surface area, so that it is possible to reduce the thermal resistance of the interface BD2 between the base member 20a and the bonding layer 30. Furthermore, since the large-diameter filler FL having a grain size larger than the average grain size of the filler F is in contact with the surface 20DS defining the recessed portion 20D, it is possible to further reduce the thermal resistance of the interface BD2.

[0047] <Modifications of this embodiment> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit and scope of the invention. For example, the following modifications are also possible.

[0048] In the above embodiment, a plurality of heater electrodes formed of a conductive material such as tungsten or molybdenum may be further provided inside the holding member 10. In such a case, when an object is held by the holding member 10, the heater electrodes generate heat by power supplied from an external power source, thereby making it possible to warm the object.

[0049] In the above embodiment, the holding devices H and Ha satisfy all of the conditions (A) to (C), but this is not limiting. The holding devices H and Ha only need to satisfy at least one of the conditions (A) to (C).

[0050] In the above embodiment, the condition (A) is satisfied by the plurality of fillers F contained in the bonding layer 30 including both the first filler F1 (filler F in contact with the holding member 10) and the second filler F2 (filler F in contact with the base member 20), but this is not limited thereto. The condition (A) may be satisfied by the plurality of fillers F contained in the bonding layer 30 including only one of the first filler F1 and the second filler F2.

[0051] In the above embodiment, both the first filler F1 and the second filler F2 include a large diameter filler and a small diameter filler, but this is not limited to this. Each of the first filler F1 and the second filler F2 may include only one of a large diameter filler and a small diameter filler.

[0052] In the above embodiment, the sum of the cross-sectional areas of the large diameter fillers is larger than the sum of the cross-sectional areas of the small diameter fillers in both the first filler F1 and the second filler F2, but this is not limited to the above. The sum of the cross-sectional areas of the large diameter fillers may be larger than the sum of the cross-sectional areas of the small diameter fillers in only one of the first filler F1 and the second filler F2. Alternatively, the sum of the cross-sectional areas of the large diameter fillers may be smaller than the sum of the cross-sectional areas of the small diameter fillers in both the first filler F1 and the second filler F2.

[0053] In the above embodiment, condition (B) is satisfied when both the value obtained by dividing the first ratio by the third ratio and the value obtained by dividing the second ratio by the third ratio are 0.5 or more, but this is not limited thereto. Condition (B) may be satisfied when only one of the value obtained by dividing the first ratio by the third ratio and the value obtained by dividing the second ratio by the third ratio is 0.5 or more.

[0054] In the above embodiment, both the first filler F1 and the second filler F2 contain filler F with an aspect ratio of 1.4 or more and filler F with an aspect ratio of less than 1.4, but this is not limited thereto. Each of the first filler F1 and the second filler F2 may contain only one of filler F with an aspect ratio of 1.4 or more and filler F with an aspect ratio of less than 1.4.

[0055] In the above embodiment, in both the first filler F1 and the second filler F2, the sum of the cross-sectional areas of the fillers F having an aspect ratio of 1.4 or more is larger than the sum of the cross-sectional areas of the fillers F having an aspect ratio of less than 1.4, but this is not limited thereto. In only one of the first filler F1 and the second filler F2, the sum of the cross-sectional areas of the fillers F having an aspect ratio of 1.4 or more may be larger than the sum of the cross-sectional areas of the fillers F having an aspect ratio of less than 1.4. Alternatively, in both the first filler F1 and the second filler F2, the sum of the cross-sectional areas of the fillers F having an aspect ratio of 1.4 or more may be smaller than the sum of the cross-sectional areas of the fillers F having an aspect ratio of less than 1.4.

[0056] In the second embodiment, the recess 20D is formed in the portion of the base member 20a that is bonded to the bonding layer 30, but this is not limited thereto. A similar recess may be formed in the portion of the holding member 10 that is bonded to the bonding layer 30. Even in this embodiment, when large-diameter filler FL having a particle size larger than the average particle size of the filler F is in contact with the surface that defines the recess, the thermal resistance of the interface BD1 (see FIG. 2, etc.) can be further reduced. Moreover, instead of or in addition to the large-diameter filler FL, filler F having an aspect ratio of 1.4 or more may be in contact with the surface that defines the recess 20D or the surface that defines the recess formed in the holding member 10. Even in this embodiment, the thermal resistance of the interfaces BD1 and BD2 (see FIG. 2, etc.) can be further reduced.

[0057] Although the present aspect has been described above based on the embodiment and modified examples, the above-mentioned embodiment of the aspect is intended to facilitate understanding of the present aspect and does not limit the present aspect. The present aspect may be modified or improved without departing from the spirit and scope of the claims, and equivalents are included in the present aspect. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

[0058] The present invention can also be realized in the following forms. [Application example 1] A holding device, comprising: A holding member having a holding surface for holding an object; a base member disposed on the holding member on an opposite side to the holding surface; a bonding layer that bonds the holding member and the base member and includes a plurality of fillers; A holding device characterized by satisfying at least one of the following conditions (A) to (C): Condition (A): The filler includes at least one of a first filler in contact with the holding member and a second filler in contact with the base member. Condition (B): When a first ratio is a ratio of the total cross-sectional area of ​​the filler in the bonding layer within a range of 1 μm or less from the interface with the holding member, a second ratio is a ratio of the total cross-sectional area of ​​the filler in the bonding layer within a range of 1 μm or less from the interface with the base member, and a third ratio is a ratio of the total cross-sectional area of ​​the filler in the bonding layer within a range of 30% or less of the thickness of the bonding layer from the center in the thickness direction of the bonding layer to the holding member side and within a range of 30% or less of the thickness of the bonding layer from the center to the base member side, at least one of the values ​​obtained by dividing the first ratio by the third ratio and the second ratio by the third ratio is 0.5 or more. Condition (C): Among the fillers, the amount of the fillers having an aspect ratio of 1.4 or more is greater than the amount of the fillers having an aspect ratio of less than 1.4. [Application example 2] The holding device according to Application Example 1, The holding device satisfies at least the condition (A), A holding device, characterized in that at least one of the first filler and the second filler contained in the bonding layer contains a large-diameter filler having a particle size larger than the average particle size of the filler. [Application example 3] The holding device according to Application Example 1 or Application Example 2, The holding device satisfies at least the condition (A), A holding device, characterized in that at least one of the first filler and the second filler contained in the bonding layer contains a small diameter filler having a particle size smaller than the average particle size. [Application example 4] The holding device according to any one of Application Examples 1 to 3, The holding device satisfies at least the condition (A), A holding device, characterized in that in at least one of the first filler and the second filler contained in the bonding layer, the sum of the cross-sectional areas of the large diameter fillers is greater than the sum of the cross-sectional areas of the small diameter fillers. [Application example 5] The holding device according to any one of Application Examples 1 to 4, The holding device satisfies at least the condition (A), A holding device, characterized in that at least one of the first filler and the second filler contained in the bonding layer contains the filler having an aspect ratio of 1.4 or more. [Application Example 6] The holding device according to any one of Application Examples 1 to 5, The holding device satisfies at least the condition (A), A holding device, characterized in that at least one of the first filler and the second filler contained in the bonding layer contains the filler having an aspect ratio of less than 1.4. [Application Example 7] The holding device according to any one of Application Examples 1 to 6, The holding device satisfies at least the condition (A), A holding device, characterized in that, in at least one of the first filler and the second filler contained in the bonding layer, the sum of the cross-sectional areas of the fillers having an aspect ratio of 1.4 or more is greater than the sum of the cross-sectional areas of the fillers having an aspect ratio of less than 1.4. [Application Example 8] The holding device according to any one of Application Examples 1 to 7, The holding device satisfies at least the condition (A), At least one of a portion of the holding member bonded to the bonding layer and a portion of the base member bonded to the bonding layer has a recess that is recessed deeper than an average particle size of the filler, the depth of the depression is greater than the average grain size, and the depression is filled with the bonding layer; A holding device, characterized in that a large-diameter filler having a particle size larger than the average particle size of the filler is in contact with a surface defining the recessed portion. [Application Example 9] The holding device according to any one of Application Examples 1 to 8, The holding device satisfies at least the condition (A), At least one of a portion of the holding member bonded to the bonding layer and a portion of the base member bonded to the bonding layer has a recess that is recessed deeper than an average particle size of the filler, the depth of the depression is greater than the average grain size, and the depression is filled with the bonding layer; A retention device, characterized in that the filler, having an aspect ratio of 1.4 or more, is in contact with a surface defining the recess. [Example 10] 1. An electrostatic chuck comprising: A holding device according to any one of Application Examples 1 to 9, and an electrostatic electrode that generates an electrostatic attractive force on the holding surface. [Explanation of symbols]

[0059] 1...Electrostatic chuck 10...Retaining member 10f…Holding surface 12...Electrostatic electrode 14…Beer 20, 20a...Base member 20D…Recess 20DS…side 22... Coolant flow path 30...Joining layer 40…Through hole 42...Insulating material 44…Metallized layer 46…Connection terminal 48...Terminal fitting F…Filler F1…First filler F2…Second filler H,Ha...Holding device

Claims

1. A holding device, comprising: A holding member having a holding surface for holding an object; a base member disposed on the holding member on an opposite side to the holding surface; a bonding layer that bonds the holding member and the base member and includes a plurality of fillers; Among the following conditions (A) to (C), at least the condition (A) and the condition (C) are satisfied, Condition (A): The filler includes at least one of a first filler in contact with the holding member and a second filler in contact with the base member. Condition (B): When a first ratio is a ratio of the sum of the cross-sectional area of ​​the filler in the bonding layer within a range of 1 μm or less from the interface with the holding member, a second ratio is a ratio of the sum of the cross-sectional area of ​​the filler in the bonding layer within a range of 1 μm or less from the interface with the base member, and a third ratio is a ratio of the sum of the cross-sectional area of ​​the filler in the bonding layer within a range of 30% or less of the thickness of the bonding layer from the center in the thickness direction of the bonding layer to the holding member side and within a range of 30% or less of the thickness of the bonding layer from the center to the base member side, at least one of the values ​​obtained by dividing the first ratio by the third ratio and the values ​​obtained by dividing the second ratio by the third ratio is 0.5 or more. Condition (C): The amount of the fillers having an aspect ratio of 1.4 or more is greater than the amount of the fillers having an aspect ratio of less than 1.

4. A holding device, characterized in that at least one of the first filler and the second filler contained in the bonding layer contains the filler having an aspect ratio of less than 1.

4.

2. 2. The holding device according to claim 1, The holding device satisfies at least the condition (A), A holding device, characterized in that at least one of the first filler and the second filler contained in the bonding layer contains a large-diameter filler having a particle size larger than the average particle size of the filler.

3. 3. The holding device according to claim 2, The holding device satisfies at least the condition (A), A holding device, characterized in that at least one of the first filler and the second filler contained in the bonding layer contains a small diameter filler having a particle size smaller than the average particle size.

4. 4. The holding device according to claim 3, The holding device satisfies at least the condition (A), A holding device, characterized in that in at least one of the first filler and the second filler contained in the bonding layer, the sum of the cross-sectional areas of the large diameter fillers is greater than the sum of the cross-sectional areas of the small diameter fillers.

5. 2. The holding device according to claim 1, The holding device satisfies at least the condition (A), A holding device, characterized in that at least one of the first filler and the second filler contained in the bonding layer contains the filler having an aspect ratio of 1.4 or more.

6. 6. The holding device according to claim 5, The holding device satisfies at least the condition (A), A holding device, characterized in that, in at least one of the first filler and the second filler contained in the bonding layer, the sum of the cross-sectional areas of the fillers having an aspect ratio of 1.4 or more is greater than the sum of the cross-sectional areas of the fillers having an aspect ratio of less than 1.

4.

7. 2. The holding device according to claim 1, The holding device satisfies at least the condition (A), At least one of a portion of the holding member bonded to the bonding layer and a portion of the base member bonded to the bonding layer has a recess that is recessed deeper than an average particle size of the filler, the depth of the recess is greater than the average grain size, and the recess is filled with the bonding layer; A holding device, characterized in that a surface defining the recess is in contact with a large-diameter filler having a particle size larger than the average particle size of the filler.

8. 2. The holding device according to claim 1, The holding device satisfies at least the condition (A), At least one of a portion of the holding member bonded to the bonding layer and a portion of the base member bonded to the bonding layer has a recess that is recessed deeper than an average particle size of the filler, the depth of the recess is greater than the average grain size, and the recess is filled with the bonding layer; A retention device, characterized in that the filler, having an aspect ratio of 1.4 or more, is in contact with a surface defining the recess.

9. A holding device, comprising: A holding member having a holding surface for holding an object; a base member disposed on the holding member on an opposite side to the holding surface; a bonding layer that bonds the holding member and the base member and includes a plurality of fillers; Among the following conditions (A) to (C), at least condition (A) is satisfied, Condition (A): The filler includes at least one of a first filler in contact with the holding member and a second filler in contact with the base member. Condition (B): When a first ratio is a ratio of the sum of the cross-sectional area of ​​the filler in the bonding layer within a range of 1 μm or less from the interface with the holding member, a second ratio is a ratio of the sum of the cross-sectional area of ​​the filler in the bonding layer within a range of 1 μm or less from the interface with the base member, and a third ratio is a ratio of the sum of the cross-sectional area of ​​the filler in the bonding layer within a range of 30% or less of the thickness of the bonding layer from the center in the thickness direction of the bonding layer to the holding member side and within a range of 30% or less of the thickness of the bonding layer from the center to the base member side, at least one of the values ​​obtained by dividing the first ratio by the third ratio and the values ​​obtained by dividing the second ratio by the third ratio is 0.5 or more. Condition (C): The amount of the fillers having an aspect ratio of 1.4 or more is greater than the amount of the fillers having an aspect ratio of less than 1.

4. At least one of the first filler and the second filler contained in the bonding layer contains a large-diameter filler having a particle size larger than an average particle size of the filler, At least one of the first filler and the second filler contained in the bonding layer contains a small diameter filler having a particle diameter smaller than the average particle diameter, A holding device, characterized in that in at least one of the first filler and the second filler contained in the bonding layer, the sum of the cross-sectional areas of the large diameter fillers is greater than the sum of the cross-sectional areas of the small diameter fillers.

10. A holding device, comprising: A holding member having a holding surface for holding an object; a base member disposed on the holding member on an opposite side to the holding surface; a bonding layer that bonds the holding member and the base member and includes a plurality of fillers; Among the following conditions (A) to (C), at least condition (A) is satisfied, Condition (A): The filler includes at least one of a first filler in contact with the holding member and a second filler in contact with the base member. Condition (B): When a first ratio is a ratio of the sum of the cross-sectional area of ​​the filler in the bonding layer within a range of 1 μm or less from the interface with the holding member, a second ratio is a ratio of the sum of the cross-sectional area of ​​the filler in the bonding layer within a range of 1 μm or less from the interface with the base member, and a third ratio is a ratio of the sum of the cross-sectional area of ​​the filler in the bonding layer within a range of 30% or less of the thickness of the bonding layer from the center in the thickness direction of the bonding layer to the holding member side and within a range of 30% or less of the thickness of the bonding layer from the center to the base member side, at least one of the values ​​obtained by dividing the first ratio by the third ratio and the values ​​obtained by dividing the second ratio by the third ratio is 0.5 or more. Condition (C): The amount of the fillers having an aspect ratio of 1.4 or more is greater than the amount of the fillers having an aspect ratio of less than 1.

4. At least one of the first filler and the second filler contained in the bonding layer has an aspect ratio of 1.4 or more, At least one of the first filler and the second filler contained in the bonding layer includes the filler having an aspect ratio of less than 1.4, A holding device, characterized in that, in at least one of the first filler and the second filler contained in the bonding layer, the sum of the cross-sectional areas of the fillers having an aspect ratio of 1.4 or more is greater than the sum of the cross-sectional areas of the fillers having an aspect ratio of less than 1.

4.

11. A holding device, comprising: A holding member having a holding surface for holding an object; a base member disposed on the holding member on an opposite side to the holding surface; a bonding layer that bonds the holding member and the base member and includes a plurality of fillers; Among the following conditions (A) to (C), at least condition (A) is satisfied, Condition (A): The filler includes at least one of a first filler in contact with the holding member and a second filler in contact with the base member. Condition (B): When a first ratio is a ratio of the sum of the cross-sectional area of ​​the filler in the bonding layer within a range of 1 μm or less from the interface with the holding member, a second ratio is a ratio of the sum of the cross-sectional area of ​​the filler in the bonding layer within a range of 1 μm or less from the interface with the base member, and a third ratio is a ratio of the sum of the cross-sectional area of ​​the filler in the bonding layer within a range of 30% or less of the thickness of the bonding layer from the center in the thickness direction of the bonding layer to the holding member side and within a range of 30% or less of the thickness of the bonding layer from the center to the base member side, at least one of the values ​​obtained by dividing the first ratio by the third ratio and the values ​​obtained by dividing the second ratio by the third ratio is 0.5 or more. Condition (C): The amount of the fillers having an aspect ratio of 1.4 or more is greater than the amount of the fillers having an aspect ratio of less than 1.

4. At least one of a portion of the holding member bonded to the bonding layer and a portion of the base member bonded to the bonding layer has a recess that is recessed deeper than an average particle size of the filler, the depth of the recess is greater than the average grain size, and the recess is filled with the bonding layer; A holding device, characterized in that a surface defining the recess is in contact with a large-diameter filler having a particle size larger than the average particle size of the filler.

12. A holding device, comprising: A holding member having a holding surface for holding an object; a base member disposed on the holding member on an opposite side to the holding surface; a bonding layer that bonds the holding member and the base member and includes a plurality of fillers; Among the following conditions (A) to (C), at least condition (A) is satisfied, Condition (A): The filler includes at least one of a first filler in contact with the holding member and a second filler in contact with the base member. Condition (B): When a first ratio is a ratio of the sum of the cross-sectional area of ​​the filler in the bonding layer within a range of 1 μm or less from the interface with the holding member, a second ratio is a ratio of the sum of the cross-sectional area of ​​the filler in the bonding layer within a range of 1 μm or less from the interface with the base member, and a third ratio is a ratio of the sum of the cross-sectional area of ​​the filler in the bonding layer within a range of 30% or less of the thickness of the bonding layer from the center in the thickness direction of the bonding layer to the holding member side and within a range of 30% or less of the thickness of the bonding layer from the center to the base member side, at least one of the values ​​obtained by dividing the first ratio by the third ratio and the values ​​obtained by dividing the second ratio by the third ratio is 0.5 or more. Condition (C): The amount of the fillers having an aspect ratio of 1.4 or more is greater than the amount of the fillers having an aspect ratio of less than 1.

4. At least one of a portion of the holding member bonded to the bonding layer and a portion of the base member bonded to the bonding layer has a recess that is recessed deeper than an average particle size of the filler, the depth of the recess is greater than the average grain size, and the recess is filled with the bonding layer; A retention device, characterized in that the filler, having an aspect ratio of 1.4 or more, is in contact with a surface defining the recess.

13. 1. An electrostatic chuck comprising: A holding device according to any one of claims 1 to 12, and an electrostatic electrode that generates an electrostatic attractive force on the holding surface.

Images