Electrostatic chuck member and electrostatic chuck device

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

[0001] This application claims priority to Japanese Patent Application No. 2023-158380, filed September 22, 2023, the contents of which are incorporated herein by reference.

[0002] Electrostatic chuck devices for supporting a substrate such as a semiconductor wafer are known. For example, Patent Document 1 describes such an electrostatic chuck device having a structure in which a sample stage that electrostatically attracts an object to be processed has a plurality of gas holes for supplying a heat transfer gas between the object to be processed and the sample stage to control the temperature of the object to be processed.

[0003] JP 2010-182763 A

[0004] In the electrostatic chuck device described above, the gas supply through-holes can be the origin of discharges that can lead to damage to the semiconductor wafer. In recent years, plasma etching devices for semiconductor manufacturing have become increasingly powerful for drilling deep holes due to the increasing number of semiconductor layers. Therefore, there is a need to suppress the occurrence of abnormal discharges inside the gas holes.

[0005] An object of the present invention is to provide an electrostatic chuck device capable of suppressing abnormal discharge inside a gas hole.

[0006] 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 mounted and a gas hole penetrating in the 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 so as to surround the gas hole, wherein the discharge-suppressing member is provided electrically independently. [2] The electrostatic chuck member according to [1], wherein the discharge-suppressing member includes a plurality of pins arranged at intervals in a circumferential direction around a central axis of the gas hole and each of which 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 around the central axis of the gas hole and continuous 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 the 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 the opposite side of the mounting surface with respect to the chucking electrode and the bias electrode, the conductive shield layer extending radially outward from the 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 the opposite side of the mounting surface, wherein the discharge suppressing member is not in contact with the base.

[0007] According to one aspect of the present invention, there is provided an electrostatic chuck device capable of suppressing abnormal discharge inside a gas hole.

[0008] FIG. 1 is a schematic cross-sectional view showing 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 according to 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 a second embodiment. FIG. 4 is a diagram showing an example of equipotential lines near a gas hole of an electrostatic chuck device according to a comparative example that does not have a discharge-suppressing member. FIG. 5 is a diagram showing an example of equipotential lines near a gas hole (a portion where a pin is located) of an electrostatic chuck device according to an example of the first embodiment. FIG. 6 is a diagram showing an example of equipotential lines in another portion (a portion between the pins) near the gas hole of the electrostatic chuck device according to an 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 modification of the embodiment.

[0009] Preferred examples of each embodiment of the electrostatic chuck device of the present invention will be described below with reference to the drawings. In all of the following drawings, the dimensions and ratios of each component may be displayed differently as appropriate to make the drawings easier to understand. The following explanations are provided to provide a more detailed explanation for a better understanding of the gist of the invention, and do 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.

[0010] [First Embodiment] (Entire Electrostatic Chuck Device) FIG. 1 is a schematic cross-sectional view showing a preferred example of an electrostatic chuck device according to this embodiment. The electrostatic chuck device 1A shown in FIG. 1 is placed in a vacuum chamber of a plasma processing apparatus with a mounting surface 11a on which a wafer (plate-shaped sample) W is placed facing upward. Each drawing shows the Z-axis to explain the reference of the electrostatic chuck device. The Z-axis direction is, for example, the vertical direction. The central axis O of the mounting surface 11a is parallel to the Z-axis. The arrangement of the electrostatic chuck device 1A in the vertical direction is merely an example, and other arrangements may be used.

[0011] The electrostatic chuck device 1A includes an electrostatic chuck plate (electrostatic chuck member) 10A that attracts and supports a plate-shaped sample such as a wafer W, and a base 20 that supports the electrostatic chuck plate 10A.

[0012] (Base) The base 20 is made of a thick, disk-shaped member. The base 20 supports the electrostatic chuck plate 10A from the underside (opposite the mounting surface 11a). The material constituting the base 20 can be selected as needed, and metals with excellent thermal conductivity, electrical conductivity, and processability, composite materials containing these metals, conductive ceramics, or composite materials of the metals and ceramics (MMC: Metal Matrix Composition) are preferably used. Suitable examples of the metal include aluminum, aluminum alloys, copper, copper alloys, and stainless steel. 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 to the conductive material constituting the conductive ceramics can be selected as desired, but is preferably 10:90 to 90:10. Examples of highly thermally conductive materials include AlN, SiC, GaN, and 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 The conductive material is preferably at least one selected from the group consisting of C, carbon, aluminum, copper, silver, and gold. ２ , TiN, TiC, W, WC, Mo, MoC, Mo ２ Preferably, the conductive ceramic is at least one selected from the group consisting of C, TaC, TaN, NbC, VC, and C. The conductive ceramic may be composed of, for example, AlN and TiN, AlN and Mo, or AlN, TiN, and Mo. The base 20 of this embodiment may be a water-cooled base having a flow path (not shown) therein for circulating a coolant such as water.

[0013] The upper surface 20t of the base 20 is bonded 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.

[0014] (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.

[0015] (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 orientation of the electrostatic chuck device when in use, and do not limit the orientation of the electrostatic chuck device when in use.

[0016] The dielectric substrate 11 is preferably made of a composite sintered body that has mechanical strength and durability against corrosive gases and their plasma. Ceramics that have mechanical strength and durability against corrosive gases and their plasma are preferably used as the dielectric material that constitutes the dielectric substrate 11. Suitable ceramics that constitute the dielectric substrate 11 include, for example, aluminum oxide sintered body, aluminum nitride sintered body, and aluminum oxide-silicon carbide composite sintered body.

[0017] The upper surface of the dielectric substrate 11 is configured 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 formed with recesses 13 between adjacent plurality of 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).

[0018] The dielectric substrate 11 is provided with gas holes 8. The gas holes 8 penetrate the dielectric substrate 11 in the thickness direction. The gas holes 8 are circular when viewed in the thickness direction. The gas holes 8 are connected to a gas supply device (not shown). The gas holes 8 supply a cooling gas such as helium (He) to a 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 a plurality of gas holes 8 may be provided in the electrostatic chuck device 1A.

[0019] (Adsorption Electrode and Bias Electrode) The adsorption electrode 30 and the bias electrode 40 are layer electrodes embedded in the dielectric substrate 11 and are conductive members. The adsorption electrode 30 and the bias electrode 40 are conductive. That is, the adsorption electrode 30 and the bias electrode 40 are made of a material with a resistivity of 0.5 Ωm or less. The adsorption electrode 30 and the bias electrode 40 are arranged in this order from top to bottom within the dielectric substrate 11. In other words, the adsorption electrode 30 is preferably arranged between the bias electrode 40 and the mounting surface 11a.

[0020] The chucking electrode 30 is located inside the dielectric substrate 11. The chucking electrode 30 extends in a layer shape along a plane perpendicular to the thickness direction of the dielectric substrate 11. The chucking electrode 30 is preferably provided with first holes 30a through which the discharge suppressing member 50A passes. The first holes 30a are regions formed to surround the discharge suppressing member 50A when viewed from the thickness direction, and in which the hole-shaped chucking electrodes 30 are not formed. The inner diameter of the first holes 30a is sufficiently larger than the outer diameter of the discharge suppressing member 50A. The inner edge of the first holes 30a is disposed at a distance from the outer peripheral surface of the discharge suppressing member 50A.

[0021] The chucking electrode 30 is disposed a predetermined distance below the mounting surface 11a and the bottom surface 13b. The chucking electrode 30 is connected to a DC power supply 101 via a first power supply 31 extending downward. The chucking electrode 30 generates an electrostatic chucking force by a DC current supplied from the DC power supply 101, thereby attracting the wafer W to the mounting surface 11a. The chucking electrode 30 is not limited to a monopolar chucking electrode, but may be a bipolar chucking electrode consisting of two semicircular electrodes in a plan view. Furthermore, the chucking electrode 30 may be provided only in a partial region in the circumferential direction around the discharge suppressing member 50A (described later) as viewed in the thickness direction. The number and shape of the chucking electrodes 30 may be selected arbitrarily. Furthermore, a plurality of chucking electrodes 30 may be provided at intervals in the circumferential direction around the discharge suppressing member 50A as viewed in the thickness direction.

[0022] 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 supply 102 via a second power supply portion 41 extending downward.

[0023] The bias electrode 40 preferably has a second hole 40a through which the discharge suppressing 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 formed to surround the discharge suppressing member 50A when viewed from the thickness direction and in which the bias electrode 30 is not formed. The inner diameter of the second hole 40a is sufficiently larger than the outer diameter of the discharge suppressing member 50A. The inner edge of the second hole 40a is disposed at a distance from the outer peripheral surface of the discharge suppressing 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 formed to surround the first power supply 31 when viewed from the thickness direction and in which the bias electrode 30 is not formed. 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 portion 40 h is disposed at a distance from the outer peripheral surface of the first power supply portion 31 .

[0024] In this embodiment, the outer circumferential edge 40b of the bias electrode 40 and the outer circumferential edge 30b of the chucking electrode 30 are disposed at approximately the same position as viewed in the thickness direction. As a result, in this embodiment, the bias electrode 40 is disposed so as to cover almost the entire chucking electrode 30 from below. Note that it is sufficient that at least a portion of the bias electrode 40 overlaps with the chucking electrode 30 as viewed in the thickness direction. In other words, at least a portion of the bias electrode 40 overlaps with the chucking electrode 30 as viewed in the thickness direction. Furthermore, the bias electrode 40 of this embodiment entirely overlaps with the chucking electrode 30 as viewed in the thickness direction.

[0025] (Discharge Suppressing Member) FIG. 2 is a cross-sectional schematic diagram showing a discharge suppressing member 50A provided in the electrostatic chuck device 1A of this embodiment. This figure is a schematic diagram of the discharge suppressing member 50A surrounding the gas hole 8, cut in the radial direction. As shown in FIGS. 1 and 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 pins 51 are arranged on the same circle, spaced apart from one another in the circumferential direction around the gas hole 8. Each pin 51 extends in the thickness direction of the dielectric substrate 11. The pins 51 are, for example, circular when viewed in the thickness direction. The number, shape, and size of the pins 51 can be selected arbitrarily. The shape of the pins 51 is not limited to a circle when viewed in the thickness direction, and may be a polygonal shape such as a square, pentagon, hexagon, or octagon. The pins 51 may be, for example, cylindrical or polygonal prisms. 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 holes 8 to the pins 51 can be selected arbitrarily, and may be, for example, less than or equal to the diameter of the gas holes 8. In this embodiment, the shape of the pins 51 and the distance from the gas holes 8 to each pin 51 are all the same.

[0026] These multiple pins 51 are provided radially outwardly of and spaced apart from the inner circumferential surface of the gas hole 8. In other words, the dielectric material forming the dielectric substrate 11 is interposed between the multiple pins 51 constituting the discharge suppressing member 50A and the inner circumferential surface of the gas hole 8.

[0027] 1, one end 51s of each pin 51 is disposed a predetermined distance below the mounting surface 11a and the bottom surface 13b. The other end 51t of each pin 51 is disposed 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.

[0028] The discharge suppressing member 50A, which includes the multiple pins 51, is provided electrically independent. That is, 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 suppressing member 50A may be in direct contact only with the dielectric material that forms the dielectric substrate 11.

[0029] The attraction electrode 30, the bias electrode 40, and the discharge suppressing member 50A are made of a conductive material. The conductive material used for the discharge suppressing member 50A can be selected arbitrarily, and molybdenum carbide (MoC) is preferred. ２ Preferably, the conductive material used for the attraction electrode 30, the bias electrode 40, and the discharge suppressing member 50A is at least one selected from the group consisting of 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 attraction electrode 30, the bias electrode 40, and the discharge suppressing member 50A may further contain 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) and SmAlO ３ At least one of the above may be added.

[0030] The chucking electrode 30, the bias electrode 40, and the discharge-suppressing member 50A may be formed in advance into a predetermined shape, or may be formed by three-dimensional printing, etc. The chucking electrode 30, the bias electrode 40, and the discharge-suppressing member 50A may be arranged so that they are embedded in the dielectric substrate 11 successively while the dielectric substrate 11 is formed by laminating the dielectric substrate 11 in multiple steps.

[0031] 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 at each portion inside the dielectric substrate 11 due to the voltages applied to these electrodes 30, 40. The electrostatic chuck plate 10A of this embodiment includes a conductive discharge-suppressing member 50A provided 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-suppressing 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 into the gas hole 8. As a result, a large potential difference is unlikely to occur inside the gas hole 8, and discharge of the cooling gas through the gas hole 8 can be suppressed.

[0032] The discharge suppressing member 50A of this embodiment is embedded in the dielectric substrate 11 so as to surround the gas hole 8 and suppress 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 located radially inside the discharge suppressing member 50A. Therefore, it is possible to suppress abnormal discharge within the gas hole 8.

[0033] In the electrostatic chuck plate 10A of the present embodiment, the discharge suppressing member 50A includes a plurality of pins 51 that are arranged at intervals in the circumferential direction around the central axis of the gas hole 8. With this simple configuration, abnormal discharge inside the gas hole 8 can be suppressed.

[0034] In the electrostatic chuck plate 10A of the present embodiment, the discharge suppressing member 50A is provided radially outwardly of the gas hole 8 and spaced apart from the inner circumferential surface of the gas hole 8. According to this configuration, the dielectric material forming the dielectric substrate 11 is interposed between the inner circumferential surface of the gas hole 8 and the discharge suppressing member 50A, which more effectively prevents the electric field generated by the chucking electrode 30 and the bias electrode 40 from extending radially inwardly of the discharge suppressing member 50A.

[0035] 3 is a cross-sectional schematic view showing a discharge suppressing member provided in an electrostatic chuck device according to a second embodiment. An electrostatic chuck device 1B according to this embodiment differs from the electrostatic chuck device 1A in the configuration of a 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 a description of the configuration common to the electrostatic chuck device 1A will be omitted.

[0036] 1, an 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 attraction electrode 30, a bias electrode 40, and a discharge suppressing member 50B.

[0037] 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 around the gas hole 8 as a center when viewed in 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 in the thickness direction, and is cylindrical as a whole. The cross-sectional shape of the discharge suppressing member 50B when viewed in the thickness direction is not limited to a circle, and may be a polygonal shape such as a square, hexagon, or octagon.

[0038] The discharge suppressing member 50B is disposed radially outside the gas hole 8 and spaced apart from the inner circumferential surface of the gas hole 8. In other words, the 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.

[0039] The discharge suppressing member 50B is provided electrically independent. That is, the discharge suppressing 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 suppressing member 50B is located inside the dielectric substrate 11 and is not exposed to the outside.

[0040] The discharge suppressing member 50B of this embodiment is embedded in the dielectric substrate 11 so as to surround the gas hole 8 and suppress discharge inside the gas hole 8. With this configuration, the discharge suppressing member 50B can suppress 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 50B. As a result, it is possible to effectively suppress the potential difference from increasing in the gas hole 8 located radially inside the discharge suppressing member 50B. Therefore, it is possible to suppress abnormal discharge inside the gas hole 8.

[0041] In the electrostatic chuck plate 10B of this embodiment, the discharge suppressing member 50B is formed in a cylindrical shape that extends in the circumferential direction about 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 attraction electrode 30 and the bias electrode 40 from extending radially inward of the discharge suppressing member 50B over the entire circumferential area of ​​the discharge suppressing member 50B. As a result, it is possible to effectively suppress discharge of the cooling gas at the gas hole 8.

[0042] It is generally known that a wafer W mounted on the mounting surface 11a emits secondary electrons from the underside of the wafer W when an etching gas impinges on the upper surface. Furthermore, the frequency of such secondary electron emission has increased in recent years with the increasing power of etching. When secondary electrons emitted from the underside of the wafer W enter the gas holes 8, the cooling gas in the gas holes 8 may be ionized, causing discharge within the gas holes 8. The inventors have noted that discharge due to ionization of the cooling gas is likely to occur when there is a large potential difference in the thickness direction within the gas holes 8 between the underside of the wafer W and the upper surface of the base 20. The inventors have attempted to reduce the potential difference within the gas holes 8, and have devised the configurations of the respective embodiments and their modified examples.

[0043] (Example: Simulation) A simulation was conducted to demonstrate the superiority of an electrostatic chuck device having a discharge suppressing member. FIGS. 4 to 7 show simulation results demonstrating the superiority of the electrostatic chuck device 1A of the first embodiment and the electrostatic chuck device 1B of the second embodiment. The configurations of the devices were simplified in the simulations to facilitate comparison. FIG. 4 shows simulation results for an electrostatic chuck device 1P as a comparative example, which does not have a discharge suppressing member 50A. FIGS. 5 and 6 show simulation results for the electrostatic chuck device 1A of the first embodiment. The electrostatic chuck device 1A shown in FIGS. 5 and 6 includes a discharge suppressing member 50A, unlike the electrostatic chuck device 1P of the comparative example shown in FIG. 4. FIG. 7 shows simulation results for an electrostatic chuck device 1B of an example of the second embodiment. The electrostatic chuck device 1B includes a discharge suppressing member 50B, unlike the electrostatic chuck device 1P of the comparative example shown in FIG. 4. FIGS. 4 to 7 schematically show simulation results of equipotential lines of the electric field generated by the attraction electrode 30 and the bias electrode 40.

[0044] In the electrostatic chuck device 1P of the comparative example shown in Fig. 4, equipotential lines are concentrated and arranged vertically around the area below the wafer W where the gas holes 8 are provided, and it can be seen that the potential difference is large below the wafer W. On the other hand, in the simulation results for the electrostatic chuck device 1A shown in Figs. 5 and 6, most of the equipotential lines emanating 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 area where the discharge suppressing member 50A is provided, both in the area where the pins 51 are provided (see Fig. 5) and in the area between adjacent pins 51 in the circumferential direction (see Fig. 6). In the simulation results for the electrostatic chuck device 1B of the example shown in Fig. 7, most of the equipotential lines emanating 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 area where the discharge suppressing member 50B is provided. The number of equipotential lines arranged below the wafer W in the simulation results for electrostatic chuck devices 1A and 1B as examples is smaller than the number of equipotential lines arranged below the wafer W in the simulation results for electrostatic chuck device 1P as the comparative example. This confirms that the potential difference below the wafer W is smaller in electrostatic chuck devices 1A and 1B of the examples.

[0045] 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 descriptions thereof will be omitted.

[0046] 8 , similarly to the above-described embodiment, an electrostatic chuck device 1C according to this modification includes an electrostatic chuck plate 10C and a base 20. The electrostatic chuck plate 10C also includes a dielectric substrate 11, an attraction electrode 30, a bias electrode 40, and a discharge-suppressing member 50C.

[0047] The discharge suppressing 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 the bias electrode 40 (on the side opposite to the mounting surface 11a) and spaced apart from these electrodes. The shield layer 55 extends in a layered form along a plane perpendicular to the thickness direction of the dielectric substrate 11.

[0048] The shield layer 55 contacts the outer peripheral surface of the cylindrical discharge suppressing member 50C and is electrically connected to the discharge suppressing member 50C. The shield layer 55 extends radially outward from the outer peripheral surface of the discharge suppressing member 50C. In this embodiment, the shield layer 55 is formed in a flange shape extending annularly in the circumferential direction. The radial width of the shield layer 55 may be constant. The shield layer 55 may be provided only on a portion of the circumferential direction. For example, multiple shield layers 55 may be provided at intervals in the circumferential direction. In this case, the multiple shield layers 55 extend radially from the outer peripheral surface of the discharge suppressing member 50C. The multiple shield layers 55 may have any number and shape. For example, when viewed in the thickness direction, each may be rectangular, approximately rectangular, fan-shaped, or other shape. In this embodiment, the outer edge 55s located radially outward of the shield layer 55 entirely overlaps the bias electrode 40 when viewed in the thickness direction. The discharge suppressing member 50C and the shield layer 55 may be formed from the same material. The discharge suppressing member 50C and the shield layer 55 may be in direct contact only with the dielectric material forming the dielectric substrate 11 .

[0049] The electrostatic chuck plate 10C of this modification includes a conductive shield layer 55 that 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 that extends radially outward from the outer circumferential surface of 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 holes 8 below the discharge suppressing member 50C, and to suppress discharge of the cooling gas at the gas holes 8.

[0050] While the embodiments and modifications of the present invention have been described above, the configurations and combinations thereof in the embodiments and modifications are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the embodiments.

[0051] DESCRIPTION OF SYMBOLS 1A to 1C... Electrostatic chuck device 1P Electrostatic chuck device (comparative example) 8 Gas hole 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 portion 30b Outer periphery 31 First power supply portion 40 Bias electrode 40a Second hole portion 40b Outer periphery 40h Third hole portion 41 Second power supply portion 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 supply 102 AC power supply O Central axis W Wafer (plate-shaped sample) Z Z axis

Claims

1. An electrostatic chuck member comprising: a plate-shaped dielectric substrate having a mounting surface on which a plate-shaped sample is placed and having gas holes penetrating in the 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 so as to surround the gas holes, wherein the discharge-suppressing member is provided electrically independent.

2. An electrostatic chuck member as described in claim 1, wherein the discharge suppressing member includes a plurality of pins spaced apart in the circumferential direction around the central axis of the gas hole, each pin continuing in the thickness direction.

3. An electrostatic chuck member according to claim 1, wherein the discharge suppressing member is formed in a cylindrical shape extending circumferentially around the central axis of the gas hole and continuing in the thickness direction.

4. The electrostatic chuck member according to claim 1, wherein the discharge suppressing member is provided radially outward of the gas hole and spaced apart from the inner circumferential surface of the gas hole.

5. The electrostatic chuck member according to claim 1, further comprising a conductive shielding layer disposed inside the dielectric substrate on the opposite side of the mounting surface relative to the chucking electrode and the bias electrode, and extending radially outward from the outer circumferential surface of the discharge suppressing member centered on the discharge suppressing member.

6. An electrostatic chuck device comprising: an electrostatic chuck member according to any one of claims 1 to 5; and a base supporting said electrostatic chuck member from the side opposite said mounting surface, wherein said discharge suppressing member is not in contact with said base.

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