WO2025063032A1 - Electrostatic chuck member and electrostatic chuck device - Google Patents

Abstract

This electrostatic chuck member comprises: a plate-like dielectric substrate provided with a placement surface on which a plate-like sample is placed and a gas hole which penetrates in a thickness direction; an adsorption electrode disposed to the inside of the dielectric substrate; a bias electrode disposed to the inside of the dielectric substrate; and a conductive discharge suppression member embedded in the dielectric substrate so as to surround the gas hole. The discharge suppression member is provided so as to be electrically independent.

Description

Electrostatic chuck member and electrostatic chuck device

The present invention relates to an electrostatic chuck member and an electrostatic chuck device.
This application claims priority based on Japanese Patent Application No. 2023-158380, filed on September 22, 2023, the contents of which are incorporated herein by reference.

Electrostatic chuck devices that support substrates such as semiconductor wafers are known. For example, Patent Document 1 describes such an electrostatic chuck device having a configuration in which a sample stage that electrostatically attracts the workpiece has multiple gas holes that supply heat transfer gas between the workpiece and the sample stage to control the temperature of the workpiece.

JP 2010-182763 A

In electrostatic chuck devices such as those described above, the gas supply through-holes can be the starting point of discharges that can lead to damage to semiconductor wafers. In recent years, plasma etching devices used in semiconductor manufacturing have become increasingly powerful in order to process deep holes due to the increasing number of semiconductor layers. For this reason, there is a need to suppress the occurrence of abnormal discharges inside the gas holes.

One of the objectives of the present invention is to provide an electrostatic chuck device that can suppress abnormal discharge inside the gas hole.

The present invention includes the following inventions [1] to [6].
It is also preferable to combine two or more of the following inventions as necessary.
[1] An electrostatic chuck member comprising: a plate-shaped dielectric substrate having a mounting surface on which a plate-shaped sample is placed and gas holes penetrating in a thickness direction, an attraction electrode disposed inside the dielectric substrate, a bias electrode disposed inside the dielectric substrate, and a conductive discharge-suppressing member embedded in the dielectric substrate to surround the gas holes, wherein the discharge-suppressing member is provided electrically independent.
[2] The electrostatic chuck member according to [1], wherein the discharge suppressing member includes a plurality of pins that are spaced apart in a circumferential direction around a central axis of the gas hole and each of the pins is continuous in the thickness direction.
[3] The electrostatic chuck member according to [1], wherein the discharge suppressing member is formed in a cylindrical shape extending in a circumferential direction about a central axis of the gas hole and continuing in the thickness direction.
[4] The electrostatic chuck member according to any one of [1] to [3], wherein the discharge suppressing member is provided radially outward of the gas hole and spaced apart from an inner circumferential surface of the gas hole.
[5] The electrostatic chuck member according to any one of [1] to [4], further comprising a conductive shield layer disposed inside the dielectric substrate on a side opposite to the mounting surface side with respect to the attraction electrode and the bias electrode, and extending radially outward from an outer circumferential surface of the discharge-suppressing member centered on the discharge-suppressing member.
[6] An electrostatic chuck device comprising: the electrostatic chuck member according to any one of [1] to [5]; and a base supporting the electrostatic chuck member from an opposite side to the mounting surface, wherein the discharge suppressing member is not in contact with the base.

According to one aspect of the present invention, an electrostatic chuck device is provided that can suppress abnormal discharge inside the gas hole.

FIG. 1 is a schematic cross-sectional view illustrating an example of an electrostatic chuck device according to a first embodiment. FIG. 2 is a schematic cross-sectional view showing an example of a discharge suppressing member provided in the electrostatic chuck device of the first embodiment. FIG. 3 is a schematic cross-sectional view showing an example of a discharge suppressing member provided in the electrostatic chuck device according to the second embodiment. FIG. 4 is a diagram showing an example of equipotential lines near gas holes of an electrostatic chuck device of a comparative example that does not have a discharge suppressing member. FIG. 5 is a diagram showing an example of equipotential lines in the vicinity of a gas hole (a portion where a pin is located) of an electrostatic chuck device in an example of the first embodiment. FIG. 6 is a diagram showing an example of equipotential lines in another portion (portion between pins) near the gas holes of the electrostatic chuck device in the example of the first embodiment. FIG. 7 is a diagram showing an example of equipotential lines of an electrostatic chuck device according to an example of the second embodiment. FIG. 8 is a schematic cross-sectional view of an electrostatic chuck device according to a modified example of the embodiment.

Hereinafter, preferred examples of each embodiment of the electrostatic chuck device of the present invention will be described with reference to the drawings. In all of the following drawings, the dimensions and ratios of each component may be appropriately changed in order to make the drawings easier to understand.
The following description is given in detail to allow the gist of the invention to be better understood, and does not limit the present invention unless otherwise specified. For example, unless otherwise specified, conditions such as materials, amounts, types, numbers, sizes, shapes, positions, combinations, and ratios may be changed, added, or omitted as necessary.

[First embodiment]
(Overall electrostatic chuck device)
FIG. 1 is a schematic cross-sectional view showing a preferred example of an electrostatic chuck device according to the present embodiment.
An electrostatic chuck device 1A shown in FIG. 1 is placed in a vacuum chamber of a plasma processing device with a mounting surface 11a on which a wafer (plate-shaped sample) W is placed facing upward.
In each drawing, a Z-axis is shown to explain the reference of the electrostatic chuck device. The Z-axis direction is, for example, a vertical direction. The central axis O of the mounting surface 11a is parallel to the Z-axis. Note that the arrangement of the electrostatic chuck device 1A with respect to the vertical direction is one example, and other arrangements may be used.

The electrostatic chuck device 1A includes an electrostatic chuck plate (electrostatic chuck member) 10A that adsorbs and supports a plate-shaped sample such as a wafer W, and a base 20 that supports the electrostatic chuck plate 10A.

(Foundation)
The base 20 is made of a thick disk-shaped member. The base 20 supports the electrostatic chuck plate 10A from the lower side (opposite the mounting surface 11a). The material constituting the base 20 can be selected as necessary, and metals having excellent thermal conductivity, electrical conductivity, and workability, or composite materials containing these metals, or conductive ceramics, or composite materials of the metals and ceramics (MMC: Metal Matrix Composition) are preferably used. As the metal, for example, aluminum, aluminum alloys, copper, copper alloys, stainless steel, etc. are preferably used. The conductive ceramics are preferably composed of a highly thermally conductive material and a conductive material.
The volume ratio of the highly thermally conductive material and the conductive material constituting the conductive ceramics can be selected arbitrarily, but is preferably 10:90 to 90:10. The highly thermally conductive material is preferably at least one selected from the group consisting of AlN, SiC, GaN, SiO ₂ , Al ₂ O ₃ , SmAlO ₃ , MgO, SiO ₂ , Si ₃ N ₄ , Al(OH) ₃ , MgO, Mg(OH) ₂ , BN, ZnO, BeO, B ₄ C, carbon, aluminum, copper, silver, and gold. The conductive material is preferably at least one selected from the group consisting of SiC, TiO ₂ , TiN, TiC, W, WC, Mo, MoC, Mo ₂ C, TaC, TaN, NbC, VC, and C. The conductive ceramic may be made of AlN and TiN, may be made of AlN and Mo, or may be made of AlN, TiN and Mo, for example.
The base 20 of the present embodiment may be a water-cooled base having a flow path (not shown) therein for circulating a coolant such as water.

The upper surface 20t of the base 20 is adhered to the lower surface 11b of the dielectric substrate 11 via an adhesive layer 25. The adhesive layer 25 can be selected arbitrarily, and may be, for example, a heat-resistant resin such as polyimide resin, silicone resin, or epoxy resin, or an insulating sheet- or film-shaped adhesive resin, or a silicone resin containing a highly thermally conductive filler such as aluminum nitride particles or surface-coated aluminum nitride particles, or a metal brazing material.

(Electrostatic chuck plate)
The electrostatic chuck plate 10A includes a dielectric substrate 11, an attraction electrode 30, a bias electrode 40, and a discharge-suppressing member 50A. The attraction electrode 30, the bias electrode 40, and the discharge-suppressing member 50A are each embedded in the dielectric substrate 11.

(Dielectric Substrate)
The dielectric substrate 11 is a plate-like member that is circular or approximately circular in plan view. In this specification, the thickness direction of the dielectric substrate 11 may be simply referred to as the "thickness direction". In this specification, the electrostatic chuck device will be described with the side in the thickness direction on which the wafer W is mounted being referred to as the "upper side" and the opposite side being referred to as the "lower side". In this specification, the "upper side" and the "lower side" indicate examples of the posture of the electrostatic chuck device when in use, and do not limit the posture of the electrostatic chuck device when in use.

The dielectric substrate 11 is preferably made of a composite sintered body that has mechanical strength and is resistant to corrosive gases and their plasma. As the dielectric material that constitutes the dielectric substrate 11, ceramics that have mechanical strength and are resistant to corrosive gases and their plasma are preferably used. As the ceramics that constitute the dielectric substrate 11, for example, aluminum oxide sintered body, aluminum nitride sintered body, aluminum oxide-silicon carbide composite sintered body, etc. are preferably used.

The upper surface of the dielectric substrate 11 is provided with a mounting surface 11a on which the wafer W is placed. That is, the dielectric substrate 11 is provided with the mounting surface 11a on which the wafer W is placed. In this embodiment, a plurality of protrusions 12 are formed at predetermined intervals on the upper surface of the dielectric substrate 11. The tip surfaces of the plurality of protrusions 12 form the mounting surface 11a. The dielectric substrate 11 is provided with recesses 13 between adjacent protrusions 12, which are recessed downward from the mounting surface 11a. The bottom surface 13b of the recesses 13 faces upward (towards the wafer W).

The dielectric substrate 11 is provided with a gas hole 8. The gas hole 8 penetrates the dielectric substrate 11 in the thickness direction. The gas hole 8 is circular when viewed in the thickness direction. The gas hole 8 is connected to a gas supply device (not shown). The gas hole 8 supplies a cooling gas such as helium (He) to the space between the wafer W placed on the mounting surface 11a and the bottom surface 13b of the recess 13. The supplied cooling gas cools the wafer W placed on the mounting surface 11a. In this embodiment, a case will be described in which only one gas hole 8 is formed in the center of the electrostatic chuck device 1A, but multiple gas holes 8 may be provided in the electrostatic chuck device 1A.

(Adsorption electrode and bias electrode)
The chucking electrode 30 and the bias electrode 40 are layered electrodes embedded in the dielectric substrate 11 and are conductive members. The chucking electrode 30 and the bias electrode 40 are conductive. That is, the chucking electrode 30 and the bias electrode 40 are made of a material having a resistivity of 0.5 Ωm or less. The chucking electrode 30 and the bias electrode 40 are arranged in this order from the top to the bottom in the dielectric substrate 11. In other words, the chucking electrode 30 is preferably arranged between the bias electrode 40 and the mounting surface 11a.

The chucking electrode 30 is located inside the dielectric substrate 11. The chucking electrode 30 extends in a layer along a plane perpendicular to the thickness direction of the dielectric substrate 11. The chucking electrode 30 is preferably provided with a first hole 30a through which the discharge suppressing member 50A passes. The first hole 30a is an area in which the hole-shaped chucking electrode 30 is not formed, and is formed to surround the discharge suppressing member 50A when viewed from the thickness direction. The inner diameter of the first hole 30a is sufficiently larger than the outer diameter of the discharge suppressing member 50A. The inner edge of the first hole 30a is disposed at a distance from the outer peripheral surface of the discharge suppressing member 50A.

The chucking electrode 30 is disposed at a predetermined distance below the mounting surface 11a and the bottom surface 13b. The chucking electrode 30 is connected to the DC power source 101 via the first power supply 31 extending downward. The chucking electrode 30 generates an electrostatic chucking force by the DC current supplied from the DC power source 101, and chucking the wafer W to the mounting surface 11a. The chucking electrode 30 is not limited to a monopolar chucking electrode, and may be a bipolar chucking electrode consisting of two electrodes having a semicircular shape in a plan view. The chucking electrode 30 may be provided only in a partial area in the circumferential direction centered on the discharge suppressing member 50A described later, as viewed from the thickness direction. The number and shape of the chucking electrodes 30 are arbitrarily selected. The chucking electrodes 30 may be provided at intervals in the circumferential direction centered on the discharge suppressing member 50A, as viewed from the thickness direction.

The bias electrode 40 is disposed below the chucking electrode 30 (opposite the mounting surface 11a) and spaced apart from the chucking electrode 30. The bias electrode 40 extends in a layer shape along a plane perpendicular to the thickness direction of the dielectric substrate 11. The bias electrode 40 is connected to the AC power source 102 via a second power supply 41 that extends downward.

The bias electrode 40 is preferably provided with a second hole 40a through which the discharge suppression member 50A passes and a third hole 40h through which the first power supply 31 passes. The second hole 40a is a hole-shaped region in which the bias electrode 30 is not formed, formed to surround the discharge suppression member 50A when viewed from the thickness direction. The inner diameter of the second hole 40a is sufficiently larger than the outer diameter of the discharge suppression member 50A. The inner edge of the second hole 40a is disposed at a distance from the outer peripheral surface of the discharge suppression member 50A. In this embodiment, the inner diameter of the second hole 40a is approximately equal to the inner diameter of the first hole 30a. Similarly, the third hole 40h is a hole-shaped region in which the bias electrode 30 is not formed, formed to surround the first power supply 31 when viewed from the thickness direction. The inner diameter of the third hole 40h is sufficiently larger than the outer diameter of the first power supply 31. The inner edge of the third hole 40h is spaced apart from the outer circumferential surface of the first power supply part 31.

In this embodiment, the outer periphery 40b of the bias electrode 40 and the outer periphery 30b of the adsorption electrode 30 are positioned at approximately the same position when viewed from the thickness direction. As a result, in this embodiment, the bias electrode 40 is positioned so as to cover almost the entire adsorption electrode 30 from below. Note that it is sufficient that at least a portion of the bias electrode 40 overlaps with the adsorption electrode 30 when viewed from the thickness direction. In other words, at least a portion of the bias electrode 40 overlaps with the adsorption electrode 30 when viewed from the thickness direction. Furthermore, the bias electrode 40 in this embodiment entirely overlaps with the adsorption electrode 30 when viewed from the thickness direction.

(Discharge suppressing member)
2 is a schematic cross-sectional view showing a discharge suppressing member 50A provided in the electrostatic chuck device 1A of the present embodiment. This figure is a schematic cross-sectional view of the discharge suppressing member 50A surrounding the inside of the gas hole 8, cut in the radial direction.
As shown in FIG. 1 and FIG. 2, the discharge suppressing member 50A is embedded in the dielectric substrate 11 so as to surround the gas hole 8. The discharge suppressing member 50A suppresses discharge in the gas hole 8. The discharge suppressing member 50A of this embodiment includes a plurality of pins 51 surrounding the gas hole 8. The plurality of pins 51 are arranged on the same circle at intervals in the circumferential direction centered on the gas hole 8. Each pin 51 extends in the thickness direction of the dielectric substrate 11. The pin 51 is, for example, circular when viewed from the thickness direction. The number, shape, and size of the pins 51 can be selected arbitrarily. The shape of the pin 51 is not limited to a circle when viewed from the thickness direction, and may be, for example, a polygonal shape such as a square, a pentagon, a hexagon, or an octagon. The pin 51 may be, for example, a cylinder or a polygonal column. The number of pins 51 may be, for example, three or more. In this embodiment, six pins 51 are arranged at equal intervals in the circumferential direction. The number of pins may be, for example, 3 to 5, 6 to 8, 9 to 15, or 16 to 25. The distance from the gas hole 8 to the pin 51 can be selected arbitrarily, and may be, for example, equal to or less than the diameter of the gas hole 8, or equal to or more than the diameter. In this embodiment, the shape of the pins 51 and the distance from the gas hole 8 to each pin 51 are all the same.

These multiple pins 51 are spaced apart from the inner circumferential surface of the gas hole 8 on the radially outer side of the gas hole 8. In other words, the dielectric material that forms the dielectric substrate 11 is interposed between the multiple pins 51 that make up the discharge suppression member 50A and the inner circumferential surface of the gas hole 8.

Also, as shown in FIG. 1, one end 51s of each pin 51 is positioned a predetermined distance below the mounting surface 11a and bottom surface 13b. The other end 51t of each pin 51 is positioned a predetermined distance above the lower surface 11b of the dielectric substrate 11. In other words, each pin 51 is not in contact with the metal base 20. The ends of the pins 51 are located inside the dielectric substrate 11 and are not exposed to the outside.

The discharge suppression member 50A, which has multiple pins 51, is provided electrically independent. In other words, the multiple pins 51 embedded in the dielectric substrate 11 are not electrically connected to other conductors, such as the chucking electrode 30 or the bias electrode 40. For example, the discharge suppression member 50A may be in direct contact only with the dielectric material that forms the dielectric substrate 11.

The chucking electrode 30, the bias electrode 40, and the discharge suppressing member 50A are formed of a conductive material. The conductive material used for the discharge suppressing member 50A can be selected arbitrarily, and is preferably at least one selected from the group consisting of molybdenum carbide (Mo ₂ C), molybdenum (Mo), tungsten carbide (WC), tungsten (W), tantalum carbide (TaC), tantalum (Ta), silicon carbide (SiC), carbon black, carbon nanotubes, and carbon nanofibers. The conductive material used for the chucking electrode 30, the bias electrode 40, and the discharge suppressing member 50A may further be configured by adding at least one of aluminum oxide (Al ₂ O ₃ ), aluminum nitride (AlN), silicon nitride (Si ₃ N ₄ ), yttrium (III) oxide (Y ₂ O ₃ ), yttrium aluminum garnet (YAG), SmAlO ₃ , etc., in order to control the resistivity.

These chucking electrodes 30, bias electrodes 40, and discharge suppressing members 50A may be formed in advance into a predetermined shape, or may be formed by 3D printing or the like. The chucking electrodes 30, bias electrodes 40, and discharge suppressing members 50A may be arranged so that they are embedded in the dielectric substrate 11 in sequence as the dielectric substrate 11 is laminated and formed in multiple steps.

In the electrostatic chuck plate 10A of this embodiment, the chucking electrode 30 and the bias electrode 40 are disposed inside the dielectric substrate 11, and therefore a potential difference occurs in each part of the dielectric substrate 11 due to the voltage applied to these electrodes 30, 40. The electrostatic chuck plate 10A of this embodiment includes a conductive discharge suppression member 50A arranged to surround the gas hole 8 of the dielectric substrate 11. With this configuration, since the gas hole 8 is surrounded by the conductive discharge suppression member 50A, it is possible to prevent the influence of the electric field of the chucking electrode 30 and the bias electrode 40 from extending to the gas hole 8. As a result, a large potential difference is unlikely to occur in the gas hole 8, and discharge of the cooling gas in the gas hole 8 can be suppressed.

The discharge suppressing member 50A of this embodiment is embedded in the dielectric substrate 11 so as to surround the gas hole 8, and suppresses discharge within the gas hole 8. With this configuration, the discharge suppressing member 50A can prevent the electric field generated by the chucking electrode 30 and the bias electrode 40 from extending to the radially inner side of the discharge suppressing member 50A. As a result, it is possible to effectively prevent the potential difference from increasing in the gas hole 8 on the radially inner side of the discharge suppressing member 50A. Therefore, it is possible to suppress abnormal discharge inside the gas hole 8.

In the electrostatic chuck plate 10A of this embodiment, the discharge suppression member 50A has a plurality of pins 51 arranged at intervals in the circumferential direction around the central axis of the gas hole 8. This simple configuration makes it possible to suppress abnormal discharge inside the gas hole 8.

In the electrostatic chuck plate 10A of this embodiment, the discharge suppression member 50A is provided at a distance from the inner peripheral surface of the gas hole 8 to the radially outer side of the gas hole 8. With this configuration, the dielectric material forming the dielectric substrate 11 is interposed between the inner peripheral surface of the gas hole 8 and the discharge suppression member 50A, and the electric field generated by the chucking electrode 30 and the bias electrode 40 can be more effectively prevented from extending to the radially inner side of the discharge suppression member 50A.

[Second embodiment]
3 is a cross-sectional schematic diagram showing a discharge suppressing member provided in the electrostatic chuck device of the second embodiment. The electrostatic chuck device 1B of the present embodiment is different from the electrostatic chuck device 1A in the configuration of the discharge suppressing member 50B, but the other configuration is common to the electrostatic chuck device 1A. Therefore, the following mainly describes the discharge suppressing member 50B, and the description of the configuration common to the electrostatic chuck device 1A will be omitted.

As shown in FIG. 1, the electrostatic chuck device 1B shown in FIG. 6 includes an electrostatic chuck plate 10B and a base 20. The electrostatic chuck plate 10B includes a dielectric substrate 11, an adsorption electrode 30, a bias electrode 40, and a discharge suppression member 50B.

The discharge suppressing member 50B is embedded in the dielectric substrate 11 so as to surround the gas hole 8. The discharge suppressing member 50B suppresses discharge in the gas hole 8. The discharge suppressing member 50B of this embodiment is formed as a cylindrical member that extends continuously in the circumferential direction centered on the gas hole 8 when viewed from the thickness direction and also continues in the thickness direction. The discharge suppressing member 50B of this embodiment has a circular (donut-shaped) cross-sectional shape when viewed from the thickness direction, and is cylindrical overall. The cross-sectional shape of the discharge suppressing member 50B when viewed from the thickness direction is not limited to a circle, and may be a polygonal shape such as a square, hexagon, or octagon.

The discharge suppressing member 50B is provided radially outside the gas hole 8 and spaced apart from the inner circumferential surface of the gas hole 8. In other words, a dielectric material forming the dielectric substrate 11 is interposed between the discharge suppressing member 50B and the inner circumferential surface of the gas hole 8.
One end 50s of the discharge suppressing member 50B is disposed a predetermined distance below the mounting surface 11a and the bottom surface 13b. The other end 50t of the discharge suppressing member 50B is disposed a predetermined distance above the lower surface 11b of the dielectric substrate 11. In other words, the discharge suppressing member 50B is not in contact with the metal base 20.

The discharge suppression member 50B is provided electrically independent. In other words, the discharge suppression member 50B embedded in the dielectric substrate 11 is not electrically connected to other conductors, such as the chucking electrode 30 and the bias electrode 40. In this embodiment, the discharge suppression member 50B is located inside the dielectric substrate 11 and is not exposed to the outside.

The discharge suppressing member 50B of this embodiment is embedded in the dielectric substrate 11 so as to surround the gas hole 8, and suppresses discharge within the gas hole 8. With this configuration, the discharge suppressing member 50B can prevent the electric field generated by the chucking electrode 30 and the bias electrode 40 from extending to the radial inside of the discharge suppressing member 50B. As a result, it is possible to effectively prevent the potential difference from increasing in the gas hole 8 on the radial inside of the discharge suppressing member 50B. Therefore, it is possible to suppress abnormal discharge inside the gas hole 8.

In the electrostatic chuck plate 10B of this embodiment, the discharge suppression member 50B is formed into a cylindrical shape that extends in the circumferential direction around the central axis of the gas hole 8 and is continuous in the thickness direction. With this configuration, it is possible to prevent the electric field generated by the chucking electrode 30 and the bias electrode 40 from extending to the radially inner side of the discharge suppression member 50B over the entire circumferential area of the discharge suppression member 50B. As a result, it is possible to effectively suppress the discharge of the cooling gas at the gas hole 8.

It is generally known that the wafer W mounted on the mounting surface 11a emits secondary electrons from the underside of the wafer W when the etching gas collides with the upper surface. The frequency of occurrence of such secondary electron emission phenomena has increased in recent years with the increase in power of etching. When secondary electrons emitted to the underside of the wafer W enter the inside of the gas hole 8, the cooling gas in the gas hole 8 may be ionized, causing discharge in the gas hole 8. The inventors have focused on the fact that discharge due to ionization of the cooling gas is likely to occur when the potential difference in the thickness direction in the gas hole 8 between the underside of the wafer W and the upper surface of the base 20 is large. The inventors have attempted to reduce the potential difference in the gas hole 8, and have come up with the configurations of each embodiment and its modified examples.

(Example: Simulation)
A simulation was performed to prove the superiority of an electrostatic chuck device having a discharge suppressing member. Simulation results showing the superiority of the electrostatic chuck device 1A of the first embodiment and the electrostatic chuck device 1B of the second embodiment were obtained in Fig. 4 to Fig. 7. Note that the configuration of the device was simplified in the simulation to facilitate comparison.
Fig. 4 shows a simulation result of an electrostatic chuck device 1P as a comparative example that does not have a discharge suppressing member 50A. Figs. 5 and 6 show a simulation result of an electrostatic chuck device 1A of the first embodiment. The electrostatic chuck device 1A shown in Figs. 5 and 6 has a discharge suppressing member 50A, unlike the electrostatic chuck device 1P of the comparative example shown in Fig. 4. Fig. 7 shows a simulation result of an electrostatic chuck device 1B of an example of the second embodiment. The electrostatic chuck device 1B has a discharge suppressing member 50B, unlike the electrostatic chuck device 1P of the comparative example shown in Fig. 4.
4 to 7 are schematic diagrams showing the results of simulations of equipotential lines of the electric field generated by the attraction electrode 30 and the bias electrode 40. In FIG.

In the comparative electrostatic chuck device 1P shown in Figure 4, equipotential lines are concentrated and arranged in a vertical line around the area below the wafer W where the gas holes 8 are provided, and it can be confirmed that the potential difference is large below the wafer W.
On the other hand, in the simulation results of the electrostatic chuck device 1A shown in Fig. 5 and Fig. 6, most of the equipotential lines extending from the end of the bias electrode 40 extend to the upper end of the electrostatic chuck plate 10A at a position radially outside the region where the discharge suppressing member 50A is provided, both in the portion where the pin 51 is provided (see Fig. 5) and in the portion between the pins 51 adjacent in the circumferential direction (see Fig. 6). In the simulation results of the electrostatic chuck device 1B of the embodiment shown in Fig. 7, most of the equipotential lines extending from the end of the bias electrode 40 extend to the upper end of the electrostatic chuck plate 10B at a position radially outside the region where the discharge suppressing member 50B is provided. The number of equipotential lines arranged on the lower side of the wafer W in the simulation results of the electrostatic chuck devices 1A and 1B as the embodiment is smaller than the number of equipotential lines arranged on the lower side of the wafer W in the simulation results of the electrostatic chuck device 1P as the comparative example. From this, it can be confirmed that the potential difference on the lower side of the wafer W is smaller in the electrostatic chuck devices 1A and 1B of the embodiment.

(Modification of the embodiment)
8 is a cross-sectional view of an electrostatic chuck device according to a modification of the second embodiment. The electrostatic chuck device 1C according to this modification is different from the electrostatic chuck device 1B according to the second embodiment described above only in the configuration of the discharge suppressing member. Note that the same components as those in the second embodiment described above are denoted by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 8, the electrostatic chuck device 1C in this modified example includes an electrostatic chuck plate 10C and a base 20, similar to the above-described embodiment. The electrostatic chuck plate 10C also includes a dielectric substrate 11, an adsorption electrode 30, a bias electrode 40, and a discharge suppression member 50C.

The discharge suppression member 50C of this modified example includes a shield layer 55. The shield layer 55 is disposed inside the dielectric substrate 11 below the chucking electrode 30 and bias electrode 40 (opposite the mounting surface 11a) and spaced apart from these electrodes. The shield layer 55 extends in layers along a plane perpendicular to the thickness direction of the dielectric substrate 11.

The shield layer 55 is in contact with the outer peripheral surface of the cylindrical discharge suppression member 50C and is electrically connected to the discharge suppression member 50C. The shield layer 55 extends radially outward from the outer peripheral surface of the discharge suppression member 50C. In this embodiment, the shield layer 55 is formed in a flange shape extending in a ring shape in the circumferential direction. The radial width of the shield layer 55 may be constant. The shield layer 55 may be provided only in a part of the circumferential direction. For example, the shield layer 55 may be provided in a plurality of parts spaced apart in the circumferential direction. In this case, the plurality of shield layers 55 extend radially from the outer peripheral surface of the discharge suppression member 50C. The plurality of shield layers 55 may be of any number or shape, and may be, for example, square, approximately square, fan-shaped, or other shapes when viewed from the thickness direction. In this embodiment, the outer edge 55s located on the radially outer side of the shield layer 55 overlaps the bias electrode 40 in its entirety when viewed from the thickness direction. The discharge suppression member 50C and the shield layer 55 may be formed from the same material. The discharge suppression member 50C and the shield layer 55 may be in direct contact only with the dielectric material that forms the dielectric substrate 11.

The electrostatic chuck plate 10C of this modified example is disposed inside the dielectric substrate 11 on the opposite side (lower side) of the mounting surface 11a with respect to the chucking electrode 30 and the bias electrode 40, and includes a conductive shield layer 55 extending radially outward from the outer circumferential surface of the discharge suppressing member 50C centered on the discharge suppressing member 50C. This allows an electric field to be formed avoiding the shield layer 55, making it difficult for a potential difference to become large below the discharge suppressing member 50C. As a result, it is possible to prevent a large potential difference from occurring within the gas hole 8 below the discharge suppressing member 50C, and it is possible to suppress discharge of the cooling gas at the gas hole 8.

The above describes the embodiments of the present invention and their variations, but each configuration and their combinations in the embodiments and variations are merely examples, and additions, omissions, substitutions and other modifications of configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the embodiments.

1A to 1C...Electrostatic chuck device 1P Electrostatic chuck device (comparative example)
8 Gas holes 10A to 10C Electrostatic chuck plate (electrostatic chuck member)
11 Dielectric substrate 11a Mounting surface 11b Lower surface 12 Protrusion 13 Recess 13b Bottom surface 20 Base 20t Upper surface 25 Adhesive layer 30 Adsorption electrode 30a First hole 30b Outer periphery 31 First power supply 40 Bias electrode 40a Second hole 40b Outer periphery 40h Third hole 41 Second power supply 50A to 50C Discharge suppressing member 50s One end 50t Other end 51 Pin 51s One end 51t Other end 55 Shield layer 101 DC power source 102 AC power source O Central axis W Wafer (plate-shaped sample)
Z Z axis

Claims (6)

a plate-shaped dielectric substrate having a mounting surface on which a plate-shaped sample is placed and a gas hole penetrating in a thickness direction;
an adsorption electrode disposed inside the dielectric substrate;
A bias electrode disposed inside the dielectric substrate;
a conductive discharge suppressing member embedded in the dielectric substrate so as to surround the gas hole,
The discharge suppressing member is provided electrically independent.
Electrostatic chuck member. The discharge suppressing member is
a plurality of pins spaced apart in a circumferential direction about a central axis of the gas hole, each pin being continuous in the thickness direction;
The electrostatic chuck member according to claim 1 . The discharge suppressing member is
The gas hole is formed in a cylindrical shape extending in a circumferential direction around a central axis of the gas hole and continuing in the thickness direction.
The electrostatic chuck member according to claim 1 . The discharge suppressing member is provided radially outward of the gas hole and spaced apart from an inner circumferential surface of the gas hole.
The electrostatic chuck member according to claim 1 . a conductive shield layer disposed inside the dielectric substrate on a side opposite to the mounting surface side with respect to the chucking electrode and the bias electrode, the conductive shield layer extending from an outer circumferential surface of the discharge suppressing member to an outer side in a radial direction centered on the discharge suppressing member,
The electrostatic chuck member according to claim 1 . An electrostatic chuck member according to any one of claims 1 to 5,
a base supporting the electrostatic chuck member from an opposite side to the mounting surface,
The discharge suppressing member is not in contact with the base.
Electrostatic chuck device.

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