JP7613992B2 - Retaining device - Google Patents

Description

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

As a holding device, for example, the electrostatic chuck described in Patent Document 1 is known. This electrostatic chuck has a ceramic plate (plate-shaped member) that holds an object on its surface (holding surface) and a metal support (base member) bonded to the plate, and internal electrodes such as a chuck electrode and a heater electrode are disposed inside the plate. This type of electrostatic chuck has multiple through holes. These through holes include lift pin holes for arranging lift pins that lift the semiconductor wafer placed on the plate and gas holes for supplying cooling gas to the back surface of the semiconductor wafer.

JP 2017-152137 A

However, in the electrostatic chuck described above, the efficiency of heat transfer between the plate-like member and the base member is poorer around the through-hole compared to other parts, and the temperature difference with other parts increases, making it easy for local temperature singularities to occur. This makes it difficult to reduce the temperature difference between the periphery of the through-hole and other parts and to uniformly control the temperature of the holding surface, and there is a risk of a decrease in thermal uniformity on the holding surface.

Therefore, this disclosure has been made to solve the above-mentioned problems, and aims to provide a holding device that can improve the thermal uniformity on the holding surface and increase the suction force.

In order to solve the above problems, one aspect of the present disclosure is to
A holding device for holding an object on the first surface of the plate-like member, the holding device comprising: a plate-like member having a first surface and a second surface provided on an opposite side to the first surface in a first direction; and a base member having a cooling function, the base member being disposed on the second surface side and thermally connected to the plate-like member, the holding device comprising:
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 chuck electrode for attracting the object, a heater electrode for heating the object, and a conductive layer electrically connected to the heater electrode are provided inside the plate-like member,
An end of the chuck electrode is disposed adjacent to the first through hole,
The end of the conductive layer includes at least a portion that is located farther from the first through hole than the end of the chuck electrode.

Here, the area around the first through hole receives less heat from the base member than other areas, so the temperature is already more likely to rise. In addition, the conductive layer connected to the heater electrode may generate heat. Heat generated by the conductive layer disposed around the first through hole causes the area around the first through hole to become hot, increasing the temperature difference with other areas, and reducing the thermal uniformity on the first surface (holding surface).

In this holding device, the conductive layer arranged around the entire circumference of the first through hole is arranged farther away from the first through hole than the chuck electrode, so that the heat generated by the conductive layer is prevented from causing the area around the first through hole to become a temperature singularity. In addition, when there are multiple heater electrodes, when the ground is shared, multiple heater electrodes are connected to one conductive layer, so that current may concentrate in the conductive layer. Therefore, in order to suppress the temperature rise around the first through hole, the conductive layer is arranged at a position relatively farther away from the first through hole, which is effective in uniforming the temperature on the first surface. In this way, this holding device can suppress the temperature rise around the first through hole, so that the thermal uniformity on the first surface can be improved.

Furthermore, in this holding device, the end of the chuck electrode is positioned close to the first through hole, so the area of the chuck electrode is increased accordingly, thereby increasing the chucking force.

Therefore, this holding device can improve the thermal uniformity on the first surface and increase the suction force.

In the above-mentioned holding device,
In a cross-sectional view in the first direction including the first through hole, it is preferable that an end of the chuck electrode is located closer to the first through hole than an end of the conductive layer.

By arranging in this manner, it is possible to improve the thermal uniformity on the first surface and increase the suction force, and since the ends of each electrode are arranged offset around the first through hole, it is possible to reliably prevent delamination from occurring in the plate-shaped member.

In the above-mentioned holding device,
It is preferable that the conductive layer is arranged around the first through holes so that the distance from one of the first through holes to the conductive layer in a second direction perpendicular to the first direction is different from the distance from the other of the first through holes to the conductive layer.

Here, a temperature rise is likely to occur around the first through hole, but the temperature rise is not uniform around the first through hole but is uneven.

Therefore, by arranging the conductive layer in this manner, for example, the distance from the first through hole can be made greater in areas where the temperature rise is large compared to areas where the temperature rise is small. As a result, in the area around the first through hole, heating by the conductive layer is suppressed in areas where the temperature rise is large, while heating by the conductive layer is promoted in areas where the temperature rise is small, thereby further improving thermal uniformity in the area around the first through hole.

In the above-mentioned holding device,
It is preferable that, around the first through hole, the end of the heater electrode includes at least a portion that is located farther from the first through hole than the end of the chuck electrode.

By arranging the heater electrode in this manner, heating by the heater electrode around the first through hole is suppressed, and the temperature rise around the first through hole can be effectively suppressed. This makes it possible to further improve the thermal uniformity on the first surface. Therefore, with this holding device, it is possible to increase the suction force and further improve the thermal uniformity on the first surface.

In the above-mentioned holding device,
The conductive layer is provided in a plurality of layers,
It is preferable that, around the first through hole, ends of the conductive layers of each layer are arranged so as to be shifted from each other so as not to overlap each other when viewed in the first direction.

In this way, by providing multiple conductive layers and staggering the ends of each conductive layer so that they do not overlap when viewed in the first direction, the distance from the first through hole can be determined arbitrarily for each conductive layer. Therefore, by heating each conductive layer, it is possible to improve the temperature controllability around the first through hole on the first surface (precise temperature adjustment).

In the above-mentioned holding device,
the heater electrode includes a first heater electrode and a second heater electrode disposed at a position different from the first heater electrode in the first direction;
It is preferable that, around the first through hole, the ends of the first heater electrode, the second heater electrode, the conductive layer electrically connected to the first heater electrode, and the conductive layer electrically connected to the second heater electrode are arranged so as to be offset from each other so as not to overlap when viewed in the first direction.

Even when many internal electrodes are provided within the plate-shaped member, by arranging the electrodes in this manner, it is possible to increase the suction force, improve the thermal uniformity on the first surface, and prevent delamination from occurring in the plate-shaped member.

In the above-mentioned holding device,
It is preferable that the plate-shaped member further includes a thermally conductive 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.

By providing such a thermally conductive bonding layer, heat transfer between the base member and the plate-shaped member is promoted, and the temperature of the base member is uniformly transferred to the second surface of the plate-shaped member, thereby further improving the thermal uniformity on the first surface.

According to the present disclosure, it is possible to provide a holding device that can improve the thermal uniformity on the first surface (holding surface) and increase the adsorption force.

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. 4 is an enlarged cross-sectional view of the vicinity of a first through hole of the plate-like member. FIG. FIG. 13 is a diagram showing a modification in which the arrangement of conductive layers is changed in the first embodiment. FIG. 11 is an enlarged cross-sectional view of the vicinity of a first through hole of a plate-shaped member in an electrostatic chuck of a second embodiment.

[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 5.

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 X, Y and Z 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 "first direction" of the present disclosure, and the radial directions (X axis direction and Y axis direction) are an example of the "second direction" of the present 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. The thermal conductivity of the plate-shaped member 10 is measured based on JIS R 1650-3:2002, and the thermal conductivity of the bonding layer 40 is measured based on JIS A 1412-2.

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 this plate-like member 10, cylindrical first through holes 15a, 15b (sometimes collectively referred to as first through holes 15) 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). The first through hole 15a constitutes a part of the lift pin insertion hole 30 that penetrates the electrostatic chuck 1 in the Z-axis direction. The first through hole 15b constitutes a part of the gas hole 31 that penetrates the electrostatic chuck 1 in the Z-axis direction.

As shown in FIG. 2, the inside of the plate-like member 10 is provided with a chuck electrode 50 made of a conductive material (e.g., tungsten, molybdenum, platinum, etc.). The shape of the chuck electrode 50 as viewed in the Z-axis direction is, for example, substantially circular. Note that the chuck electrode 50 has a hole formed therein so that the electrode is not exposed in the first through holes 15a and 15b. That is, the chuck electrode 50 has a peripheral end 50e formed around the first through holes 15 (15a and 15b) (see FIG. 5). When power is supplied to the chuck electrode 50 from a power source (not shown), an electrostatic attraction force (adsorption force) is generated, and the semiconductor wafer W is adsorbed and fixed to the holding surface 11 of the plate-like member 10 by this electrostatic attraction force.

In addition, a linear heater electrode 51 made of a conductive material (e.g., tungsten, molybdenum, platinum, etc.) is provided inside the plate-like member 10. The heater electrode 51 forms a pattern that extends in a generally spiral shape when viewed in the Z-axis direction, as shown in FIG. 4, for example. The heater electrode 51 is arranged around the first through holes 15a, 15b (away from the first through holes 15a, 15b) when viewed in the Z-axis direction so that the heater electrode 14 is not exposed near the first through holes 15a, 15b.

The heater electrode 51 has a line width of, for example, about 0.1 to 10 mm, and the heater electrode 14 has a thickness (dimension in the Z-axis direction) of, for example, about 0.02 to 3 mm. When power is supplied to the heater electrode 14 from a power source (not shown), the heater electrode 51 generates heat, which heats the holding surface 11, thereby heating the semiconductor wafer W held by the holding surface 11.

Furthermore, inside the plate-shaped member 10, conductive layers 52 and 53 made of a conductive material (e.g., tungsten, molybdenum, platinum, etc.) are provided. That is, in this embodiment, multiple conductive layers (two layers in this case) are provided. The conductive layers 52 and 53 are power supply paths (land patterns) that supply power to the heater electrode 51. The conductive layers 52 and 53 are flat and have a projected shape (circular shape) in the Z-axis direction of the plate-shaped member 10 as a whole, but each has a shape obtained by dividing the circle into multiple parts (e.g., fan shapes, etc.). The conductive layers 52 and 53 are also formed with holes so that the conductive layers are not exposed to the first through holes 15a and 15b, similar to the chuck electrode 50. That is, the conductive layers 52 and 53 have peripheral ends 52e and 53e formed around the first through holes 15 (15a and 15b) (see FIG. 5).

Here, the relative positions of the chuck electrode 50, heater electrode 51, and conductive layers 52, 53 around the first through hole 15 (15a, 15b) will be described with reference to FIG. 5. In this embodiment, as shown in FIG. 5, the chuck electrode 50 is arranged so that the end 50e is located close to the first through hole 15 (closest to the first through hole 15 among the internal electrodes). In this disclosure, "close" means that the distance from the first through hole 15 is, for example, within 5.0 mm.

The conductive layers 52 and 53 are arranged so that the ends 52e and 53e include at least a portion located farther from the first through hole 15 than the end 50e of the chuck electrode 50. That is, when the end 50e of the chuck electrode 50 and the ends 52e and 53e of the conductive layers 52 and 53 are compared (comparing some parts of each other), the end 50e of the chuck electrode 50 is arranged closer to the first through hole 15 than the ends 52e and 53e of the conductive layers 52 and 53. For example, as shown in FIG. 5, in a cross-sectional view in the Z-axis direction including the first through hole 15, the end 50e of the chuck electrode 50 may be arranged closer to the first through hole 15 than the ends 52e and 53e of the conductive layers 52 and 53.

The conductive layers 52 and 53 are arranged around the first through hole 15 such that the distances D2a and D3a from one first through hole 15 to the conductive layers 52 and 53 in the X-axis (Y-axis) direction are different from the distances D2b and D3b from the other first through hole 15 to the conductive layers 52 and 53. In other words, the conductive layers 52 and 53 are arranged so that the center of the first through hole 15 and the center of the punched holes for forming the ends 52e and 53e of the conductive layers 52 and 53 do not intentionally coincide (so as to be asymmetric around the first through hole 15). In addition, the ends 52e and 53e of the conductive layers 52 and 53 are arranged offset from each other around the first through hole 15 so as not to overlap when viewed in the Z-axis direction.

Furthermore, the heater electrode 51 is positioned around the first through hole 15 and farther away from the first through hole 15 than the chuck electrode 50.

Due to this arrangement, around the first through hole 15, the ends of the chuck electrode 50, heater electrode 51, and conductive layers 52 and 53 are shifted in the X-axis (Y-axis) direction so as not to overlap when viewed in the Z-axis direction. Also, as shown in FIG. 2, the outer peripheral ends (the outermost portions) of the chuck electrode 50, heater electrode 51, and conductive layers 52 and 53 are shifted in the X-axis (Y-axis) direction so as not to overlap when viewed in the Z-axis direction. Therefore, it is possible to reliably prevent delamination from occurring in the plate-like member 10.

As shown in Fig. 1, the base member 20 is cylindrical, more specifically, a stepped cylinder formed by stacking two cylinders of different diameters coaxially (with a common central axis) with the lower surface of the smaller diameter cylinder placed on the upper surface of the larger diameter cylinder. This 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.

As shown in Figs. 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 Z-axis direction of the base member 20 (plate-like member 10). The upper surface 21 is an example of a "third surface" in the present disclosure, and the lower surface 22 is an example of a "fourth surface" in 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 (dimension in the Z-axis direction) of the base member 20 is, for example, about 20 mm to 50 mm. The thermal conductivity of the base member 20 (assumed to be aluminum) is greater than that of the plate-like member 10, and is preferably within the range of 180 to 250 W/mK (preferably about 230 W/mK). The thermal conductivity of the base member 20 is measured based on JIS H 7903:2008, and the thermal conductivity of the plate-like member 10 is measured based on JIS R 1650-3:2002.

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 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 thereby cooled via the bonding layer 40.

The base member 20 has 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). These second through holes 25a, 25b are connected to the first through holes 15a, 15b of the plate-like member 10, respectively.

As shown in Figs. 1 and 2, the bonding layer 40 is disposed between the lower surface 12 of the plate member 10 and the upper surface 21 of the base member 20, and bonds the plate member 10 and the base member 20. The lower surface 12 of the plate member 10 and the upper surface 21 of the base member 20 are thermally connected via this bonding layer 40. This bonding layer 40 promotes heat transfer between the base member 20 and the plate member 10, and the temperature of the base member 20 is uniformly transferred to the lower surface 12 of the plate member 10. Therefore, the provision of the bonding layer 40 can contribute to uniform temperature on the holding surface 11.

The bonding layer 40 is made of a thermally conductive 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). The thermal conductivity of the bonding layer 40 is measured based on JIS A 1412-2.

2, the bonding layer 40 has through holes 45a and 45b penetrating the bonding layer 40 in the Z-axis direction. The second through holes 25a and 25b of the base member 20 communicate with the first through holes 15a and 15b through the through holes 45a and 45b. The through holes 45a and 45b are coaxial with the first through holes 15a and 15b and the second through holes 25a and 25b. The diameters of the through holes 45a and 45b are equal to those of the first through holes 15a and 15b and the second through holes 25a and 25b. The first through holes 15a and 15b, the through holes 45a and 45b, and the second through holes 25a and 25b are arranged in a row in the Z-axis direction (the axial direction of the electrostatic chuck 1).

The first through hole 15a, the 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 70 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 70 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 70 moves to one side in the Z-axis direction (upper side in FIG. 2), the tip portion (upper end portion) of the lift pin 70 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 70).

In the electrostatic chuck 1 of this embodiment, three lift pin insertion holes 30 are formed, and a lift pin 70 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 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.

In an electrostatic chuck 1 having the above-described configuration, the efficiency of heat transfer between the plate-like member 10 and the base member 20 is poor around the first through-hole 15 on the holding surface 11 compared to other parts, so the temperature difference with other parts becomes large, making it easy for localized temperature singularities to occur.

Therefore, in the electrostatic chuck 1 of this embodiment, in a cross-sectional view in the Z-axis direction including the first through hole 15, the ends 52e, 53e of the conductive layers 52, 53 arranged all around the first through hole 15 are arranged farther away from the first through hole 15 than the end 50e of the chuck electrode 50. This suppresses heating by the conductive layers 52, 53 around the first through hole 15.

Note that the conductive layers 52 and 53 only need to have their respective ends 52e and 53e positioned farther away from the first through-hole 15 than the end 50e of the chuck electrode 50. For example, as shown in FIG. 6, the conductive layer 52 may be positioned closer to the first through-hole 15 than the heater electrode 51.

When the conductive layers 52 and 53 are connected to a common ground, multiple terminals may be arranged on the conductive layers 52 and 53, causing current concentration. Therefore, in order to suppress the temperature rise around the first through hole 15, the conductive layers 52 and 53 are arranged at a position relatively farther away from the first through hole 15, which is effective in uniforming the temperature on the holding surface 11. In this way, the electrostatic chuck 1 can suppress the temperature rise around the first through hole 15, thereby improving the thermal uniformity on the holding surface 11.

In addition, in the electrostatic chuck 1, the heater electrode 51 is disposed around the first through hole 15, farther away from the first through hole 15 than the chuck electrode 50. This suppresses heating around the first through hole 15 by the heater electrode 51, effectively suppressing temperature rise around the first through hole 15. This further improves the thermal uniformity on the holding surface 11.

Furthermore, in the electrostatic chuck 1, the end 50e of the chuck electrode 50 is disposed close to the first through hole 15, so the area of the chuck electrode 50 is correspondingly larger. This increases the chucking force for holding the semiconductor wafer W on the holding surface 11. In this way, the electrostatic chuck 1 can improve the thermal uniformity on the holding surface 11 and increase the chucking force.

In addition, in the electrostatic chuck 1, the end 50e of the chuck electrode 50, the end of the heater electrode 51, and the ends 52e and 53e of the conductive layers 52 and 53 are arranged around the first through hole 15 in a shifted (non-coincident) manner when viewed in the Z-axis direction. Similarly, the outer peripheral ends (the outermost portions) of the chuck electrode 50, heater electrode 51, and conductive layers 52 and 53 are also arranged in a shifted (non-coincident) manner when viewed in the Z-axis direction. This makes it possible to reliably prevent delamination from occurring in the plate-like member 10.

Here, a temperature rise is likely to occur around the first through hole 15, but the temperature rise is not uniform around the first through hole 15. Therefore, in the electrostatic chuck 1, the conductive layers 52, 53 are arranged around the first through hole 15 so that the center of the first through hole 15 and the center of each hole for forming the ends 52e, 53e of the conductive layers 52, 53 do not intentionally coincide (asymmetric around the first through hole 15). As a result, for example, in a portion where the temperature rise is large, the distance from the first through hole 15 can be made larger than in a portion where the temperature rise is small. As a result, in the portion around the first through hole 15 where the temperature rise is large, heating by the conductive layers 52, 53 is suppressed, while heating by the conductive layers 52, 53 is promoted in the portion where the temperature rise is small, so that the thermal uniformity around the first through hole 15 can be further improved.

The ends 52e, 53e of the conductive layers 52, 53 are offset from each other so that they do not overlap when viewed in the Z-axis direction, so that the distance from the first through-hole 15 can be determined arbitrarily for each conductive layer 52, 53. Therefore, by heating the conductive layers 52, 53, it is possible to improve the temperature controllability around the first through-hole 15 on the holding surface 11 (precise temperature adjustment).

As described above, according to the electrostatic chuck 1 of this embodiment, the conductive layers 52, 53 arranged around the entire circumference of the first through hole 15 are arranged farther from the first through hole 15 than the chuck electrode 50, so that heating by the conductive layers 52, 53 around the first through hole 15 is suppressed. In addition, the heater electrode 51 is arranged farther from the first through hole 15 than the chuck electrode 50. As a result, the conductive layers 52, 53 and the heater electrode 51 are arranged relatively far from the first through hole 15, while the chuck electrode 50 is arranged relatively close to the first through hole 15. Therefore, the temperature rise around the first through hole 15 is suppressed, improving the thermal uniformity on the holding surface 11 and improving the suction force.

[Second embodiment]
Next, a second embodiment will be described. The second embodiment differs from the first embodiment in that a plurality of heater electrodes are provided. That is, in the second embodiment, two heater electrodes, a main and a sub heater electrode, are provided as heater electrodes. Therefore, the same reference numerals are used for configurations similar to those in the first embodiment, and descriptions thereof are omitted as appropriate, and the description will be centered on the differences from the first embodiment.

As shown in FIG. 7, the electrostatic chuck of this embodiment includes a first heater electrode 61, which is a main heater, and a second heater electrode 65, which is a sub-heater. The first heater electrode 61 and the second heater electrode 65 are disposed at different positions (different layers) in the Z-axis direction. That is, the first heater electrode 61 is disposed closer to the holding surface 11 than the second heater electrode 65.

In addition, conductive layers 62, 63 are provided as a power supply path to the first heater electrode 61, and conductive layers 66, 67 are provided as a power supply path to the second heater electrode 65. The ends 62e, 63e, 66e, 67e of these conductive layers 62, 63, 66, 67 are shifted so as not to overlap when viewed in the Z-axis direction, and are positioned farther away from the first through hole 15 than the chuck electrode 50. Therefore, heating by the conductive layers 62, 63, 66, 67 around the first through hole 15 is suppressed.

The first heater electrode 61 is disposed closer to the first through hole 15 than the second heater electrode 65, and the first heater electrode 61 and the second heater electrode 65 are disposed farther from the first through hole 15 in the periphery of the first through hole 15 than the chuck electrode 50. Therefore, heating by the heater electrodes 61, 65 in the periphery of the first through hole 15 is suppressed.

Therefore, in this embodiment, the temperature rise around the first through hole 15 can be effectively suppressed, and the thermal uniformity on the holding surface 11 can be improved.

In this embodiment, the chuck electrode 50 is also positioned closest to the first through hole 15. This allows the area of the chuck electrode 50 to be increased accordingly, thereby increasing the suction force for holding the semiconductor wafer W on the holding surface 11.

In this embodiment, the end 50e of the chuck electrode 50, the end of the heater electrodes 61 and 65, and the end 62e, 63e, 66e, and 67e of the conductive layers 62, 63, 66, and 67 are arranged around the first through hole 15 in a shifted (non-coincident) manner. Note that the outer peripheral ends (outermost portions) of the chuck electrode 50, heater electrodes 61 and 65, and conductive layers 62, 63, 66, and 67 are arranged in a shifted (non-coincident) manner in a Z-axis direction, as in the first embodiment. Therefore, even when many internal electrodes are arranged in the plate-shaped member 10 as in this embodiment, it is possible to reliably prevent delamination in the plate-shaped member 10.

As described above, according to the electrostatic chuck of this embodiment, even when the main and sub heater electrodes 61, 65 are provided and many internal electrodes are arranged within the plate-shaped member 10, it is possible to increase the chucking force and improve the thermal uniformity on the holding surface 11 while preventing delamination from occurring in the plate-shaped member 10.

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 addition, in the above embodiment, an electrostatic chuck 1 having multiple conductive layers 52 and 53 is illustrated, but the present disclosure can also be applied to an electrostatic chuck having a single conductive layer (e.g., only conductive layer 52).

1 Electrostatic chuck 10 Plate-like member 11 Holding surface 12 Lower surface 15 First through hole 15a First through hole 15b First through hole 20 Base member 25a Second through hole 25b Second through hole 40 Bonding layer 50 Chuck electrode 50e End 51 Heater electrode 52 Conductive layer 52e End 53 Conductive layer 53e End 61 First heater electrode 65 Second heater electrode D2a, D2b Distance D3a, D3b from first through hole 15 to conductive layer 52 Distance W from first through hole 15 to conductive layer 53 Semiconductor wafer

Claims (6)

A holding device for holding an object on the first surface of the plate-like member, the holding device comprising: a plate-like member having a first surface and a second surface provided on an opposite side to the first surface in a first direction; and a base member having a cooling function, the base member being disposed on the second surface side and thermally connected to the plate-like member, the holding device comprising:
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 chuck electrode for attracting the object, a heater electrode for heating the object, and a conductive layer electrically connected to the heater electrode are provided inside the plate-like member,
The chuck electrode has an end formed around the first through hole,
The conductive layer has an end formed around the first through hole,
An end of the chuck electrode is disposed adjacent to the first through hole,
an end of the conductive layer includes at least a portion that is disposed farther from the first through hole than an end of the chuck electrode;
The conductive layer is provided in a plurality of layers,
In the periphery of the first through hole, ends of the conductive layers of each layer are shifted from each other so as not to overlap each other when viewed in the first direction.
A holding device characterized in that 2. The holding device according to claim 1,
A holding device characterized in that, in a cross-sectional view in the first direction including the first through hole, an end of the chuck electrode is positioned closer to the first through hole than an end of the conductive layer. The holding device according to claim 1 or 2,
A holding device characterized in that the conductive layer is arranged around the first through holes so that the distance from one of the first through holes to the conductive layer in a second direction perpendicular to the first direction is different from the distance from the other of the first through holes to the conductive layer. In any one of the holding devices according to claims 1 to 3,
The heater electrode has an end formed around the first through hole,
A holding device characterized in that, around the first through hole, an end of the heater electrode includes at least a portion that is positioned farther from the first through hole than an end of the chuck electrode. In any one of the holding devices according to claims 1 to 4 ,
the heater electrode includes a first heater electrode and a second heater electrode disposed at a position different from the first heater electrode in the first direction;
the first heater electrode and the second heater electrode have ends formed around the first through hole;
A holding device characterized in that, around the first through hole, the respective ends of the first heater electrode, the second heater electrode, the conductive layer electrically connected to the first heater electrode, and the conductive layer electrically connected to the second heater electrode are arranged so as to be offset from each other so as not to overlap when viewed in the first direction. A holding device according to any one of claims 1 to 5 ,
A holding device characterized in that it has a thermally conductive 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.

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