JP7601606B2 - Retaining device - Google Patents

Description

This disclosure relates to a holding device for holding an object.

As a holding device, for example, an electrostatic chuck described in Patent Document 1 is known. This electrostatic chuck includes an electrostatic chuck substrate (ceramic member) that holds the target wafer, a base plate (base member) for cooling, and a bonding layer that bonds the two members. The electrostatic chuck substrate incorporates a heating resistor. In addition, such an electrostatic chuck is provided with through holes such as lift pin holes into which lift pins are inserted to lift up the wafer from the electrostatic chuck substrate, and gas holes for filling the gap between the surface (holding surface) of the electrostatic chuck substrate and the wafer.

Patent No. 5891332

However, in the above-mentioned holding device, the heating resistor is placed a little distance away from the through hole (in other words, to avoid the through hole) in the vicinity of the through hole to prevent exposure of the heating resistor. Therefore, the area around the through hole on the holding surface that holds the object is likely to be colder than other areas. Therefore, it has been difficult to uniform the temperature on the holding surface up to the area around the through hole.

Therefore, this disclosure has been made to solve the above-mentioned problems, and aims to provide a holding device that can equalize the temperature on the holding surface that holds the object, even around the through-hole.

In order to solve the above problems, one aspect of the present disclosure is to
A holding device having a plate-shaped member having a first surface and a second surface provided on an opposite side to the first surface, a base member having a third surface and a fourth surface provided on an opposite side to the third surface, and a bonding layer disposed between the second surface of the plate-shaped member and the third surface of the base member, bonding the plate-shaped member and the base member, the holding device holding an object on the first surface of the plate-shaped member,
a first through hole penetrating the first surface and the second surface is formed in the plate-like member;
a second through hole penetrating the third surface and the fourth surface and communicating with the first through hole is formed in the base member;
a recess is provided on the second surface around an opening of the first through hole;
the bonding layer has a thick layer portion that is disposed in at least a portion of the recess and is thicker than other portions of the recess;
The recess has a tapered shape that gradually becomes deeper in a direction toward the first surface toward the first through hole,
The thick layer portion is characterized in that it is convex toward the first surface side, on which a third through hole that connects the first through hole and the second through hole is formed in the center .

In this holding device, a recess is provided on the second surface of the plate-like member around the opening of the first through hole, and the bonding layer has a thick layer portion that is thicker than other portions that are filled in at least a portion of the recess. In other words, a thick layer portion is provided around the through hole of the plate-like member where the bonding layer is thicker than other portions. This allows the thick layer portion of the bonding layer to be disposed around the through hole, which is likely to become cold on the first surface. Therefore, the thick layer portion suppresses heat transfer between the base member and the plate-like member (cooling by the base member), and therefore it is possible to suppress a drop in temperature around the through hole. Therefore, it is possible to uniform the temperature on the first surface up to the vicinity of the through hole.

In addition, since the thick layer portion is provided on the plate-like member side rather than on the base member side, heat transfer between the base member and the plate-like member is further suppressed and the thick layer portion is located closer to the first surface, which makes it easier to control the temperature around the through holes, which tend to become cold on the first surface, and improves the temperature controllability of the first surface.
Furthermore, by forming the thick layer portion so as to be convex toward the first surface side where the third through hole that connects the first through hole and the second through hole is formed in the center, the thick layer portion can be easily formed in the bonding layer around the through hole. Also, since the thickness of the thick layer portion gradually changes, the temperature around the through hole, which tends to become low on the first surface, can be further uniformed by adjusting the rate of change in thickness according to the temperature distribution around the through hole on the first surface.

In the above-mentioned holding device,
The plate-like member has a heating resistor therein,
The heating resistor is preferably disposed so as to overlap the thick layer portion when viewed from the lamination direction of the plate-like member and the base member.

In this way, by arranging the heating resistor so that it overlaps the thick layer portion when viewed from the stacking direction of the plate-shaped member and the base member, heat from the heating resistor is less likely to be transferred to the base member. As a result, heat from the heating resistor is efficiently transferred upward (to the first surface side) of the thick layer portion. Therefore, it is possible to suppress a temperature drop around the through hole where the thick layer portion is located, and it is possible to make the temperature more uniform on the first surface up to the area around the through hole.

In the above-mentioned holding device,
The base member includes a coolant flow path for allowing a coolant to flow therethrough.
It is preferable that the coolant flow passage is disposed so as not to overlap the thick layer portion when viewed from the stacking direction of the plate-like member and the base member.

In this way, by arranging the refrigerant flow paths in the base member so that they do not overlap the thick layer portion when viewed from the stacking direction of the plate-like member and the base member, the thick layer portion is less likely to be cooled. As a result, it is possible to suppress a drop in temperature around the through hole where the thick layer portion is located, and therefore it is possible to make the temperature more uniform on the first surface up to the vicinity of the through hole.

As another aspect of the present disclosure made to solve the above problems,
A holding device having a plate-shaped member having a first surface and a second surface provided on an opposite side to the first surface, a base member having a third surface and a fourth surface provided on an opposite side to the third surface, and a bonding layer disposed between the second surface of the plate-shaped member and the third surface of the base member, bonding the plate-shaped member and the base member, the holding device holding an object on the first surface of the plate-shaped member,
a first through hole penetrating the first surface and the second surface is formed in the plate-like member;
a second through hole penetrating the third surface and the fourth surface and communicating with the first through hole is formed in the base member;
a recess is provided on the second surface so as to surround an opening of the first through hole;
The recess has a shape that deepens in a direction toward the first surface,
the bonding layer has a thick layer portion that is thicker than other portions filled in at least a portion of the recess, and is convex toward the first surface side, the third through hole being formed in the center thereof and connecting the first through hole and the second through hole;
The diameter of the third through hole may be equal to the diameter of the first through hole.

In this way, it is possible to more easily form a thick layer portion in the bonding layer around the through hole. In addition, since the volume of the thick layer portion is larger than when the recess is tapered, it is easier to suppress erosion of the bonding layer caused by plasma or corrosive gases that have entered the through hole. This makes it possible to achieve both the protective performance of the bonding layer and temperature uniformity on the first surface.

According to the present disclosure, it is possible to provide a holding device that can equalize the temperature on the holding surface that holds the object, even around the through hole.

FIG. 1 is a schematic perspective view of an electrostatic chuck according to a first embodiment. 1 is a schematic configuration diagram of an electrostatic chuck according to a first embodiment of the present invention taken along an XZ cross section; FIG. 2 is a schematic configuration diagram of the electrostatic chuck of the first embodiment in the XY plane. FIG. FIG. 11 is a schematic configuration diagram of an electrostatic chuck of a second embodiment taken along an XZ cross section; FIG. 11 is a schematic configuration diagram of an electrostatic chuck of a second embodiment taken along an XZ cross section.

[First embodiment]
A holding device according to an embodiment of the present disclosure will be described in detail with reference to the drawings. In this embodiment, an electrostatic chuck 1 that holds a semiconductor wafer W as an object will be described as an example. The electrostatic chuck 1 of this embodiment will be described with reference to FIGS. 1 to 4.

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. As shown in FIG. 1, the electrostatic chuck 1 has a plate-shaped member 10, a base member 20, and a bonding layer 40 that bonds the plate-shaped member 10 and the base member 20.

For ease of explanation, in the following description, the XYZ axes are defined as shown in FIG. 1. Here, the Z axis is the axis in the axial direction of the electrostatic chuck 1 (the vertical direction in FIG. 1), and the X and Y axes are the axes in the radial direction of the electrostatic chuck 1. The Z axis direction is an example of the "stacking direction" in this disclosure.

The plate-like member 10 is a disk-like member as shown in Fig. 1, and may be made of ceramics. Various ceramics may be used as the ceramics, but from the viewpoints of strength, wear resistance, plasma resistance, etc., it is preferable to use ceramics whose main component is, for example, aluminum oxide (alumina, _Al2O3 ) or aluminum nitride (AlN). Note that the main component here means the component with the highest content (for example, _a component with a volume content of 90 vol% or more).

The diameter of the plate-shaped member 10 is, for example, about 150 to 300 mm at the upper stage and about 180 to 350 mm at the lower stage. The thickness of the plate-shaped member 10 is, for example, about 2 to 6 mm. The thermal conductivity of the plate-shaped member 10 is preferably within a range of 10 to 50 W/mK (more preferably, 18 to 30 W/mK). The plate-shaped member 10 is formed so that the thermal conductivity of the plate-shaped member 10 is higher than the thermal conductivity of the bonding layer 40.

As shown in Figures 1 and 2, the plate-like member 10 has a holding surface 11 that holds a semiconductor wafer W, and a bottom surface 12 that is provided on the opposite side of the holding surface 11 in the thickness direction of the plate-like member 10 (the direction that coincides with the Z-axis direction, the up-down direction). Note that the holding surface 11 is an example of a "first surface" in this disclosure, and the bottom surface 12 is an example of a "second surface" in this disclosure.

The holding surface 11 of the plate-like member 10 has an uneven shape. Specifically, as shown in Figs. 2 and 3, a ring-shaped annular protrusion 16 is formed near the outer edge of the holding surface 11, and multiple independent columnar protrusions 17 are formed inside the ring-shaped protrusion 16. The ring-shaped protrusion 16 is also called a seal band. As shown in Fig. 2, the cross section (XZ cross section) of the ring-shaped protrusion 16 is substantially rectangular. The height (dimension in the Z-axis direction) of the ring-shaped protrusion 16 is, for example, about 10 μm to 20 μm. The width (dimension in the X-axis direction) of the ring-shaped protrusion 16 is, for example, about 0.5 mm to 5.0 mm.

As shown in FIG. 3, each of the protrusions 17 has a substantially circular shape when viewed in the Z-axis direction (plan view), and is arranged at substantially equal intervals. The cross-sectional shape (XZ cross-section) of each of the protrusions 17 is substantially rectangular, as shown in FIG. 2. The height of the protrusions 17 is substantially the same as the height of the annular protrusions 16, and is, for example, about 10 to 20 μm. The width of the protrusions 17 (maximum diameter of the protrusions 17 when viewed in the Z-axis direction) is, for example, about 0.5 to 1.5 mm. The portion of the holding surface 11 of the plate-like member 10 inside the annular protrusions 16 where no protrusions 17 are formed is a recess 18.

The semiconductor wafer W is supported by the annular convex portion 16 and the multiple convex portions 17 on the holding surface 11 of the plate-like member 10 and is held by the electrostatic chuck 1. When the semiconductor wafer W is held by the electrostatic chuck 1, a space S exists between the surface (lower surface) of the semiconductor wafer W and the holding surface 11 of the plate-like member 10 (more specifically, the recessed portion 18 of the holding surface 11) (see FIG. 2). An inert gas (e.g., helium gas) is supplied to this space S via a gas hole 31, which will be described later.

In such a plate-like member 10, cylindrical first through holes 15a, 15b are formed which penetrate between the holding surface 11 and the lower surface 12 in the thickness direction (Z-axis direction, up-down direction in FIG. 2). In addition, in the lower surface 12 of the plate-like member 10, a recess 13a is formed around the opening of the first through hole 15a, and a recess 13b is formed around the opening of the first through hole 15b. In this embodiment, the recesses 13a, 13b have a tapered shape which gradually becomes deeper in the direction of the holding surface 11 toward the first through holes 15a, 15b.

The plate-like member 10 also has a heater electrode 14 (heat generating resistor) therein. The heater electrode 14, for example, as shown in FIG. 4, forms a pattern that extends in a substantially spiral shape when viewed in the Z-axis direction, and is made of a conductive material (for example, tungsten, molybdenum, platinum, etc.). The heater electrode 14 is disposed near the first through holes 15a, 15b when viewed in the Z-axis direction, bypassing the first through holes 15a, 15b (away from the first through holes 15a, 15b) so that the heater electrode 14 is not exposed. The heater electrode 14 is also disposed so as to overlap the thick layer portions 42a, 42b of the bonding layer 40 described later when viewed in the Z-axis direction (see FIG. 2).

The heater electrode 14 has a line width of, for example, about 0.1 to 10 mm, and a thickness (dimension in the Z-axis direction) of, for example, about 0.02 to 3 mm. When a voltage is applied to the heater electrode 14 from a power source (not shown), the heater electrode 14 generates heat, which heats the holding surface 11, thereby heating the semiconductor wafer W held by the holding surface 11.

As shown in FIG. 1, the base member 20 is cylindrical, more specifically, a stepped cylinder formed by stacking two cylinders of different diameters with a common central axis Ca, with the lower surface of the smaller diameter cylinder placed on the upper surface of the larger diameter cylinder. The base member 20 is preferably made of a metal (e.g., aluminum or an aluminum alloy), but may be made of a material other than metal.

1 and 2, the base member 20 has an upper surface 21 and a lower surface 22 provided on the opposite side of the upper surface 21 in the direction of the central axis Ca (see FIG. 2) of the base member 20 (plate-like member 10) (i.e., the Z-axis direction). The upper surface 21 is an example of the "third surface" of the present disclosure, and the lower surface 22 is an example of the "fourth surface" of the present disclosure.

The diameter of the base member 20 is, for example, about 150 mm to 300 mm at the upper stage and about 180 mm to 350 mm at the lower stage. The thickness of the base member 20 (dimension in the Z-axis direction) is, for example, about 20 mm to 50 mm. The thermal conductivity of the base member 20 (assumed to be aluminum) is greater than that of the plate-like member 10, and is desirably within the range of 180 to 250 W/mK (preferably about 230 W/mK).

As shown in FIG. 2, the base member 20 is formed with a refrigerant flow path 23 for flowing a refrigerant (e.g., a fluorine-based inert liquid, water, etc.). The refrigerant flow path 23 is arranged so as not to overlap the recesses 13a, 13b (i.e., the thick layer portions 42a, 42b of the bonding layer 40 described later) when viewed in the Z-axis direction. The refrigerant flow path 23 is connected to a supply port and a discharge port (not shown) provided on the lower surface 22 of the base member 20, and the refrigerant supplied to the base member 20 from the supply port flows through the refrigerant flow path 23 and is discharged from the discharge port to the outside of the base member 20. In this way, the base member 20 is cooled by flowing the refrigerant through the refrigerant flow path 23 of the base member 20, and the plate-like member 10 is cooled via the bonding layer 40.

In addition, the base member 20 is formed with cylindrical second through holes 25a, 25b that penetrate between the upper surface 21 and the lower surface 22 in the thickness direction (Z-axis direction, vertical direction in FIG. 2). The second through holes 25a, 25b are coaxial with the first through holes 15a, 15b, and the diameters of the second through holes 25a, 25b are larger than the diameters of the first through holes 15a, 15b.

Furthermore, an insulating sleeve having a through hole may be fitted into the second through holes 25a and 25b of the base member 20. In this case, the second through holes 25a and 25b refer to the through holes of the sleeve, not the second through holes of the base member 20.

The bonding layer 40 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. The lower surface 12 of the plate-shaped member 10 and the upper surface 21 of the base member 20 are thermally connected via this bonding layer 40.

The bonding layer 40 includes thick layer portions 42a, 42b arranged in the recesses 13a, 13b provided on the lower surface 12 of the plate-like member 10 around the first through holes 15a, 15b, and a thin layer portion 41 that is thinner than the thick layer portions 42a, 42b. In other words, the portions of the bonding layer 40 arranged in the recesses 13a, 13b are the thick layer portions 42a, 42b, and the portions of the bonding layer 40 arranged other than the recesses 13a, 13b are the thin layer portions 41. The thick layer portions 42a, 42b are convex toward the holding surface 11, in which the third through holes 45a, 45b that connect the first through holes 15a, 15b and the second through holes 25a, 25b are formed in the center. Additionally, the periphery of the first through holes 15a, 15b refers to the area from the outer edge of the first through holes 15a, 15b to a point 10.0 mm away in the planar direction of the lower surface 12 of the plate-shaped member 10 when viewed in the axial direction of the electrostatic chuck 1.

The bonding layer 40 is made of an adhesive such as silicone resin, acrylic resin, or epoxy resin. The thickness (dimension in the Z-axis direction) of the bonding layer 40 is, for example, about 0.1 to 1.0 mm. The thermal conductivity of the bonding layer 40 is, for example, 1.0 W/mK. The thermal conductivity of the bonding layer 40 (assuming silicone resin) is preferably in the range of 0.1 to 2.0 W/mK (preferably 0.5 to 1.5 W/mK).

As described above, the bonding layer 40 has cylindrical third through holes 45a, 45b located between the first through holes 15a, 15b and the second through holes 25a, 25b (see FIG. 2). In other words, in the present embodiment, when the openings of the first through holes 15a, 15b are formed inside the recesses 13a, 13b, the bonding layer 40 is not disposed in the spaces (third through holes 45a, 45b) in the recesses 13a, 13b that communicate with the first through holes 15a, 15b and the second through holes 25a, 25b.

The third through holes 45a, 45b are coaxial with the first through holes 15a, 15b and the second through holes 25a, 25b. The diameter of the third through holes 45a, 45b is larger than that of the first through holes 15a, 15b and is equal to that of the second through holes 25a, 25b. The first through holes 15a, 15b, the third through holes 45a, 45b, and the second through holes 25a, 25b are arranged in series in the Z-axis direction (the axial direction of the electrostatic chuck 1).

The first through hole 15a, the third through hole 45a, and the second through hole 25a form a lift pin insertion hole 30 that penetrates the electrostatic chuck 1 in the Z-axis direction. A lift pin 60 that pushes up the semiconductor wafer W from above the holding surface 11 is inserted into this lift pin insertion hole 30 from the lower surface 22 side of the base member 20. This lift pin 60 has a cylindrical shape (round bar shape) and moves in the Z-axis direction inside the lift pin insertion hole 30. When the lift pin 60 moves to one side in the Z-axis direction (upper side in FIG. 2), the tip portion (upper end portion) of the lift pin 60 protrudes outward from the holding surface 11 of the plate-like member 10, and the semiconductor wafer W placed on the holding surface 11 is separated from the holding surface 11 (the semiconductor wafer W is lifted by the lift pin 60).

In the electrostatic chuck 1 of this embodiment, three lift pin insertion holes 30 are formed, and a lift pin 60 is inserted into each of the lift pin insertion holes 30. The three lift pin insertion holes 30 are formed at equal intervals in the circumferential direction of the electrostatic chuck 1 (see FIG. 3).

The first through hole 15b, the third through hole 45b, and the second through hole 25b form a gas hole 31 that penetrates the electrostatic chuck 1 in the Z-axis direction. This gas hole 31 is a gas flow path through which an inert gas (e.g., helium gas) flows. This makes it possible to fill the space S between the underside of the semiconductor wafer W and the holding surface 11 (recess 18) of the plate-like member 10 with this inert gas by supplying the inert gas (e.g., helium gas) into the gas hole 31 from the underside 22 side of the base member 20.

Here, one of the requirements for the electrostatic chuck 1 is to make the temperature uniform on the holding surface 11. However, in the electrostatic chuck 1, the heater electrode 14 is disposed at a position slightly away from the first through holes 15a, 15b (see FIG. 4). Therefore, in the vicinity of the first through holes 15a, 15b on the holding surface 11, cooling by the base member 20 is promoted more than in other parts. As a result, the temperature around the first through holes 15a, 15b is likely to be lower than in other parts, and there is a risk that the temperature on the holding surface 11 cannot be made uniform up to the vicinity of the first through holes 15a, 15b. In addition, the location slightly away from the first through holes 15a, 15b refers to the region from a point 1.0 mm away from the outer edge of the first through holes 15a, 15b in the planar direction of the lower surface 12 of the plate-shaped member 10 to a point 7.0 mm away from the outer edge of the first through holes 15a, 15b in the planar direction of the lower surface 12 of the plate-shaped member 10 when viewed in the axial direction of the electrostatic chuck 1. The portion of the heater electrode 14 closest to the first through holes 15a, 15b is located within this region.

Therefore, in the electrostatic chuck 1, as shown in FIG. 2, recesses 13a, 13b are provided around the openings of the first through holes 15a, 15b on the lower surface 12 of the plate-shaped member 10, and thick layer portions 42a, 42b of the bonding layer 40 are formed in the recesses 13a, 13b. In other words, thick layer portions 42a, 42b are provided around the first through holes 15a, 15b of the plate-shaped member 10. As a result, the thickness of the bonding layer 40 is greater around the first through holes 15a, 15b than in other portions.

Therefore, the thick layers 42a and 42b suppress heat transfer between the base member 20 and the plate-like member 10 (cooling by the base member 20). This suppresses the temperature drop around the first through holes 15a and 15b, making it possible to make the temperature uniform on the holding surface 11 up to the vicinity of the first through holes 15a and 15b.

The thick layer portions 42a and 42b are provided on the plate-shaped member 10 side, not on the base member 20 side, so that heat transfer between the base member 20 and the plate-shaped member 10 is further suppressed, and the thick layer portions 42a and 42b are located closer to the holding surface 11. This makes it easier to control the temperature around the first through holes 15a and 15b, which tend to become cold on the holding surface 11, and improves the temperature controllability on the holding surface 11. Furthermore, when the thermal expansion coefficient of the plate-shaped member 10 is smaller than that of the base member 20, the plate-shaped member 10 is less deformed by temperature changes than the base member 20. Therefore, compared to when the thick layer portions 42a and 42b are provided on the base member 20 side, providing the thick layer portions 42a and 42b on the plate-shaped member 10 side can suppress deformation of the thick layer portions 42a and 42b, and therefore can suppress the decrease in temperature uniformity of the holding surface 11 due to deformation of the thick layer portions 42a and 42b.

In addition, in the electrostatic chuck 1, the recesses 13a, 13b have a tapered shape that gradually deepens toward the holding surface 11, and the thick layer portions 42a, 42b are convex toward the holding surface 11 side, where the third through holes 45a, 45b that connect the first through holes 15a, 15b and the second through holes 25a, 25b are formed in the center. Therefore, the thick layer portions 42a, 42b can be easily formed in the bonding layer 40 around the first through holes 15a, 15b. Since the thickness of the thick layer portions 42a, 42b gradually changes, the temperature around the first through holes 15a, 15b, which is likely to become low, on the holding surface 11 can be further uniformed by adjusting the rate of change in thickness according to the temperature distribution around the first through holes 15a, 15b on the holding surface 11.

Furthermore, in the electrostatic chuck 1, the heater electrode 14 is arranged so as to overlap the thick layer portions 42a, 42b when viewed in the Z-axis direction, so that heat from the heater electrode 14 is not easily transferred to the base member 20. Therefore, the heat from the heater electrode 14 is efficiently transferred to the upper side (the holding surface 11 side) of the thick layer portions 42a, 42b. Therefore, the temperature drop around the first through holes 15a, 15b where the thick layer portions 42a, 42b are arranged can be effectively suppressed, so that the temperature can be made more uniform on the holding surface 11 up to the vicinity of the first through holes 15a, 15b.

In addition, in the electrostatic chuck 1, the coolant flow passage 23 provided in the base member 20 is arranged so as not to overlap with the thick layer portions 42a, 42b when viewed in the Z-axis direction, making it difficult for the thick layer portions 42a, 42b to be cooled. This makes it possible to suppress a decrease in temperature around the first through holes 15a, 15b in which the thick layer portions 42a, 42b are arranged. This makes it possible to make the temperature more uniform on the holding surface 11 up to the vicinity of the first through holes 15a, 15b.

As described above, according to the electrostatic chuck 1 of this embodiment, by providing the recesses 13a, 13b around the first through holes 15a, 15b and forming the thick layer portions 42a, 42b in the recesses 13a, 13b, the temperature can be made uniform on the holding surface 11 up to the vicinity of the first through holes 15a, 15b.

[Second embodiment]
Next, the second embodiment will be described. The second embodiment has the same basic structure as the first embodiment, but the shapes of the recesses provided on the lower surface of the plate-like member and the thick layer portions provided in the bonding layer are different from those of the first embodiment. That is, in the second embodiment, the recesses 113a, 113b and the thick layer portions 142a, 142b are cylindrical rather than tapered. Therefore, the same reference numerals are used for the same configurations as the first embodiment, and the description is omitted as appropriate, and the differences from the first embodiment will be mainly described.

As shown in FIG. 5, in the electrostatic chuck 101 of this embodiment, the recesses 113a and 113b provided on the lower surface 12 of the plate-like member 110 are recesses that create a step on the lower surface 12, and in this embodiment, are cylindrical spaces. The recess 113a is provided around the opening of the first through hole 15a, and the recess 113b is provided around the opening of the first through hole 15b.

The recesses 113a and 113b are filled with the bonding layer 140 to form the thick portions 142a and 142b. In this way, the thick portions 142a and 142b can be very easily formed in the bonding layer 140 around the openings of the first through holes 15a and 15b.

As shown in FIG. 5, in the electrostatic chuck 101, recesses 113a, 113b are provided around the openings of the first through holes 15a, 15b on the lower surface 12 of the plate-like member 110, and thick layer portions 142a, 142b of the bonding layer 140 are formed in the recesses 113a, 113b. In other words, thick layer portions 142a, 142b are provided around the first through holes 15a, 15b of the plate-like member 110. As a result, the thickness of the bonding layer 140 is greater around the first through holes 15a, 15b than in other portions.

Therefore, the thick layers 142a and 142b suppress heat transfer between the base member 20 and the plate-like member 110 (cooling by the base member 20). This suppresses the temperature drop around the first through holes 15a and 15b, making it possible to make the temperature uniform on the holding surface 11 up to the vicinity of the first through holes 15a and 15b.

In addition, because the thick layers 142a and 142b are provided on the plate-shaped member 110 side rather than on the base member 20 side, heat transfer between the base member 20 and the plate-shaped member 110 is further suppressed, and the thick layers 142a and 142b are positioned closer to the holding surface 11. This makes it easier to control the temperature around the first through holes 15a and 15b on the holding surface 11, which tends to become cold, and improves the temperature controllability on the holding surface 11.

Furthermore, in this embodiment, the volume of the thick layer portions 142a, 142b is larger than when the recesses are tapered as in the first embodiment, so that it is easier to suppress erosion of the bonding layer 140 caused by plasma or corrosive gas that has entered the first through holes 15a, 15b during use of the electrostatic chuck 101. Therefore, it is possible to achieve both the protective performance of the bonding layer 140 and temperature uniformity on the holding surface 11.

As described above, in the electrostatic chuck 101 of this embodiment, by providing the recesses 113a, 113b around the first through holes 15a, 15b and forming the thick layer portions 142a, 142b in the recesses 113a, 113b, the temperature can be made uniform up to the vicinity of the first through holes 15a, 15b on the holding surface 11.

The above embodiments are merely examples and do not limit the present disclosure in any way. Needless to say, various improvements and modifications are possible without departing from the spirit of the present disclosure. For example, the above embodiments illustrate the application of the present disclosure to an electrostatic chuck, but the present disclosure is not limited to electrostatic chucks and can be applied to any holding device that holds an object on its surface.

In the second embodiment, the first through holes 15a, 15b are formed in the recesses 113a, 113b provided on the lower surface 12 of the plate-like member 110, but the arrangement positions of the recesses 113a, 113b and the first through holes 15a, 15b are not limited to this. In other words, the recesses 113a, 113b may be provided around the first through holes 15a, 15b, and for example, as shown in FIG. 6, the first through holes 15a, 15b may be arranged close to the recesses 113a, 113b at the portion where the recesses 113a, 113b are formed. Even in such a case, the temperature drop around the first through holes 15a, 15b can be suppressed, so that the temperature can be made uniform up to the vicinity of the first through holes 15a, 15b on the holding surface 11.

In the above embodiment, the thick layer portions 42a, 42b, 142a, 142b are formed by filling the bonding layer 40 from the upper surface 21 of the base member 20 to the upper surface of the recesses 13a, 13b, 113a, 113b, but the thick layer portions 42a, 42b, 142a, 142b may be filled so that they are not flush with the side surfaces of the first through holes 15a, 15b or the second through holes 25a, 25b, as long as they are thicker than the thin layer portions 41, 141. Furthermore, depending on the temperature distribution, the thick layer portions 42a, 42b, 142a, 142b may be filled so that they are not flush with the side surfaces of the first through holes 15a, 15b or the second through holes 25a, 25b. This creates space in the third through holes 45a, 45b, which acts as a heat insulating layer, making it difficult for heat to escape from the plate-like member 10 and suppressing a drop in temperature around the first through holes 15a, 15b.

1 Electrostatic chuck 10 Plate-like member 11 Holding surface 12 Lower surface 13a Recess 13b Recess 14 Heater electrode 15a First through hole 15b First through hole 20 Base member 21 Upper surface 22 Lower surface 23 Coolant flow path 25a Second through hole 25b Second through hole 40 Bonding layer 42a Thick layer portion 42b Thick layer portion 101 Electrostatic chuck 110 Plate-like member 113a Recess 113b Recess 140 Bonding layer 142a Thick layer portion 142b Thick layer portion W Semiconductor wafer

Claims (4)

A holding device having a plate-shaped member having a first surface and a second surface provided on an opposite side to the first surface, a base member having a third surface and a fourth surface provided on an opposite side to the third surface, and a bonding layer disposed between the second surface of the plate-shaped member and the third surface of the base member, bonding the plate-shaped member and the base member, the holding device holding an object on the first surface of the plate-shaped member,
a first through hole penetrating the first surface and the second surface is formed in the plate-like member;
a second through hole penetrating the third surface and the fourth surface and communicating with the first through hole is formed in the base member;
a recess is provided on the second surface around an opening of the first through hole;
the bonding layer has a thick layer portion that is disposed in at least a portion of the recess and is thicker than other portions of the recess;
The recess has a tapered shape that gradually becomes deeper in a direction toward the first surface toward the first through hole,
The thick layer portion is convex toward the first surface side, and a third through hole that communicates with the first through hole and the second through hole is formed in the center of the third through hole.
A holding device characterized in that 2. The holding device according to claim 1,
The plate-like member has a heating resistor therein,
The holding device according to claim 1, wherein the heating resistor is disposed so as to overlap the thick layer portion when viewed from a direction in which the plate-like member and the base member are stacked. The holding device according to claim 1 or 2,
The base member includes a coolant flow path for allowing a coolant to flow therethrough.
The holding device according to claim 1, wherein the coolant flow path is arranged so as not to overlap the thick layer portion when viewed from a stacking direction of the plate-like member and the base member. A holding device having a plate-shaped member having a first surface and a second surface provided on an opposite side to the first surface, a base member having a third surface and a fourth surface provided on an opposite side to the third surface, and a bonding layer disposed between the second surface of the plate-shaped member and the third surface of the base member, bonding the plate-shaped member and the base member, the holding device holding an object on the first surface of the plate-shaped member,
a first through hole penetrating the first surface and the second surface is formed in the plate-like member;
a second through hole penetrating the third surface and the fourth surface and communicating with the first through hole is formed in the base member;
a recess is provided on the second surface so as to surround an opening of the first through hole;
The recess has a shape that deepens in a direction toward the first surface,
the bonding layer has a thick layer portion that is thicker than other portions filled in at least a portion of the recess, and is convex toward the first surface side, the third through hole being formed in the center thereof and connecting the first through hole and the second through hole;
The diameter of the third through hole is equal to the diameter of the first through hole.
A holding device characterized in that

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