JP7724177B2 - holding device - Google Patents

Description

The technology disclosed in this specification relates to a holding device.

One example of a holding device is an electrostatic chuck used in plasma processing for semiconductor manufacturing. When performing plasma processing on a substrate, wafer, or other object, an insulating electrostatic chuck holding the object to be processed on its upper surface is placed inside a chamber (processing vessel), and high-frequency power is applied to a conductive cooling base member located below the electrostatic chuck to generate a bias voltage on the wafer. A gas flow path is provided inside the electrostatic chuck, connecting the lower surface (the surface facing the cooling base member) with the upper surface (the wafer-holding surface). A thermally conductive gas such as helium is sent from the cooling base member side to the wafer-mounting surface through this gas flow path to improve the temperature controllability of the wafer-holding surface.

If abnormal discharge (arcing) occurs within the gas flow path due to the high-frequency power applied during plasma processing, the processing quality of wafers and other materials will deteriorate, resulting in a lower yield. Therefore, there is a need for technology that reduces the occurrence of abnormal discharge without interfering with the gas supply. For example, Patent Document 1 below discloses an electrostatic chuck in which a plug chamber is formed in part of a fine hole that serves as a gas flow path, and a porous, insulating, breathable plug placed inside the plug chamber is adhesively fixed to the wall of the plug chamber with an adhesive such as an epoxy-based resin.

Patent No. 6621548

In recent years, in order to speed up processing, the high-frequency power applied during plasma processing has become higher in voltage. As a result, the potential difference between the cooling base member and the wafer, etc., increases, making abnormal discharge more likely to occur in the gas flow path, particularly in spaces extending vertically. Therefore, it is preferable to position the insulating porous body to reduce abnormal discharge, extending to the areas facing the gas outlet and gas inlet holes formed on the upper and lower surfaces of the electrostatic chuck.

However, even if the porous body is extended to the area facing the gas outlet hole or gas inlet hole in this way, a void extending in the vertical direction still remains in the gap between the porous body and the inner surface of the gas outlet hole or gas inlet hole, and there is concern that abnormal discharge may occur in this void.

The holding device disclosed in this specification is a holding device comprising a plate-shaped member having a first surface for holding an object, a second surface located opposite the first surface, and a gas flow path through which gas can flow, the gas flow path having an outlet opening on the first surface and an inlet opening on the second surface, at least a portion of the gas flow path adjacent to the outlet or the inlet has a threaded groove on its inner circumferential surface and a threaded hole extending perpendicular to the first surface, the plate-shaped member further comprising a solid screw member having a thread on its outer circumferential surface and threaded into the threaded hole, allowing the gas to flow through the gap between the inner circumferential surface of the threaded hole and the outer circumferential surface of the screw member.

The holding device disclosed in this specification reduces the occurrence of abnormal discharges without interfering with the gas supply.

FIG. 1 is a perspective view showing a holding device according to a first embodiment, with a part cut away. FIG. 2 is a cross-sectional view of the ceramic substrate of the first embodiment. FIG. 3 is a partially enlarged cross-sectional view of the holding device of the first embodiment. FIG. 4 is an enlarged view of the area within the frame F1 in FIG. FIG. 5 is an enlarged view of the area within the frame F2 in FIG. FIG. 6 is a partially enlarged cross-sectional view of a holding device according to the first modification. FIG. 7 is a partially enlarged cross-sectional view of the holding device of the second embodiment. FIG. 8 is a cross-sectional view taken along line AA in FIG. FIG. 9 is a partially enlarged cross-sectional view of a holding device according to the second modification.

[Outline of the embodiment]
(1) The holding device disclosed in this specification is a holding device comprising a plate-like member having a first surface for holding an object, a second surface located opposite the first surface, and a gas flow path having an outlet opening on the first surface and an inlet opening on the second surface, through which gas can flow, wherein at least a portion of the gas flow path adjacent to the outlet or the inlet has a screw groove on its inner circumferential surface and a screw hole extending perpendicular to the first surface, and the plate-like member further comprises a solid screw member having a screw thread on its outer circumferential surface and being screwed into the screw hole, and the gas can flow through a gap between the inner circumferential surface of the screw hole and the outer circumferential surface of the screw member.

The above configuration allows gas to flow through the gap between the inner surface of the screw hole and the outer surface of the screw member. Because this gap is a space that extends spirally along the screw groove and thread, the size of the void space extending perpendicular to the first surface within the gas flow path, where abnormal discharge is likely to occur, can be minimized. This reduces the occurrence of abnormal discharge within the gas flow path without impeding the supply of gas.

(2) In the retaining device described in (1) above, the crest of the thread may be a surface parallel to the screw axis of the screw member, and the bottom surface of the thread groove may be a concave surface.

This configuration ensures a gap between the bottom surface of the thread groove and the crest of the thread, allowing gas to flow through.

(3) In the holding device described in (1) or (2) above, the gas flow path may have a first threaded hole adjacent to the outlet, a second threaded hole adjacent to the inlet, a first connection port opening on the inner circumferential surface of the first threaded hole, and a second connection port opening on the inner circumferential surface of the second threaded hole, thereby forming a communication flow path connecting the first threaded hole and the second threaded hole, and the first threaded member may be disposed inside the first threaded hole, and the second threaded member may be disposed inside the second threaded hole.

As described above, in a configuration in which the gas flow path has portions adjacent to the outlet and inlet, and a communicating flow path connecting the two, the portions adjacent to the outlet and inlet can be made into threaded holes and threaded members can be placed in these holes, thereby reducing the occurrence of abnormal discharge within the gas flow path.

(4) In the retaining device described in (3) above, an adhesive may be disposed on the inner surface of the first screw hole in a region farther from the first surface than the first connection port, and on the inner surface of the second screw hole in a region farther from the second surface than the second connection port, to fill the gap between the outer surfaces of the first screw member and the second screw member.

With this configuration, by disposing adhesive for fixing the screw member inside the threaded hole in an area that does not serve as a gas flow path, it is possible to prevent the screw member from falling off while maintaining a gap between the inner surface of the threaded hole and the screw member that allows gas to flow through.

(5) In the holding device described in (1) or (2) above, the gas flow path may be a threaded hole extending from the outlet perpendicular to the first surface to the inlet, and the holding device may further include a base member bonded to the second surface via an adhesive bonding layer, the bonding layer having a through hole that communicates with the outlet and has an inner diameter smaller than that of the outlet, the base member having a gas supply path that communicates with the through hole, a gap between the surface of the bonding layer and the screw member, and adhesive that fills the gap with the outer surface of the screw member may be disposed at multiple locations spaced apart in the circumferential direction on the inner surface of the threaded hole.

With this configuration, adhesive for fixing the screw member inside the threaded hole is applied at multiple locations spaced apart circumferentially, preventing the screw member from falling off while ensuring a gap for gas to flow between the inner surface of the threaded hole and the screw member. Furthermore, because there is a gap between the surface of the bonding layer and the screw member, space is secured for gas to flow from the through hole into the gap between the inner surface of the threaded hole and the outer surface of the screw member.

(6) In the holding device described in (1) or (2) above, the gas flow path is a threaded hole extending from the outlet perpendicular to the first surface to the inlet, and the holding device further includes a base member bonded to the second surface via an adhesive bonding layer, the bonding layer having a through hole communicating with the outlet, the base member having a gas supply path communicating with the through hole and having an inner diameter smaller than that of the through hole, a portion of the screw member is disposed inside the through hole, the gas can flow through a gap between the inner peripheral surface of the through hole and the outer peripheral surface of the screw member, there is a gap between the surface of the base member and the screw member, and adhesive is disposed at multiple locations spaced apart in the circumferential direction on the inner peripheral surface of the through hole to fill the gap with the outer peripheral surface of the screw member.

With this configuration, adhesive for fixing the screw member inside the threaded hole is applied at multiple locations spaced apart circumferentially, preventing the screw member from falling out while ensuring a gap for gas to flow between the inner surface of the threaded hole and the screw member. Furthermore, because there is a gap between the surface of the base member and the screw member, space is secured for gas to flow from the gas supply path into the gap between the inner surface of the through hole and the outer surface of the screw member.

[Details of the embodiment]
Specific examples of the technology disclosed in this specification will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

<Embodiment 1>
An embodiment will be described with reference to Figures 1 to 5. The holding device 1 of this embodiment is an electrostatic chuck that attracts and holds a semiconductor wafer W (hereinafter abbreviated as "wafer W"), which is an object, by electrostatic attraction while heating the object to a predetermined processing temperature (e.g., 50°C to 400°C). The electrostatic chuck is used as a table on which the wafer W is placed, for example, in a process in which etching or other processing is performed using plasma in a depressurized chamber.

[Overall configuration of holding device 1]
As shown in FIG. 1 , the holding device 1 includes a ceramic substrate 10 (an example of a plate-like member) and a base member 40 joined to the ceramic substrate 10 via a joining layer 50 .

[Ceramic substrate 10]
As shown in Fig. 2, the ceramic substrate 10 includes a substrate body 11 having an overall disk shape, and screw members 21A and 21B that are attached to the substrate body 11. The substrate body 11 is insulating and is formed from a ceramic whose main component is, for example, aluminum nitride or alumina. Note that the term "main component" here refers to the component with the highest content (weight percentage). The diameter of the substrate body 11 is, for example, approximately 50 mm to 500 mm (usually approximately 200 mm to 350 mm), and the thickness is, for example, approximately 1 mm to 10 mm.

One surface of the substrate body 11 is the first surface S1, and the other surface located opposite the first surface S1 and parallel to the first surface S1 is the second surface S2. The first surface S1 serves as an adsorption surface that adsorbs and holds the wafer W. The outer periphery of the first surface S1 is formed to protrude slightly compared to the inner periphery, and when the wafer W is adsorbed and held on the first surface S1, a gap G is formed between the wafer W and the first surface S1. A base member 40 is bonded to the second surface S2 via a bonding layer 50.

As shown in Figures 2 and 3, the interior of the substrate body 11 has an outlet 13E opening to the first surface S1 and an inlet 14E opening to the second surface S2, and is provided with multiple gas flow paths 12 through which gases such as helium can flow. Each gas flow path 12 has an outlet channel 13 (an example of a first screw hole) adjacent to the outlet 13E, an inlet channel 14 (an example of a second screw hole) adjacent to the inlet 14E, and a communicating channel 15 connecting the outlet channel 13 and the inlet channel 14.

The outflow channel 13 is a hole extending perpendicular to the first surface S1 from the outflow port 13E toward the second surface S2. The inflow channel 14 is a hole extending perpendicular to the second surface S2 from the inflow port 14E toward the first surface S1. The outflow channel 13 is a threaded hole with a screw groove 16 formed on its inner circumferential surface, and the inflow channel 14, like the outflow channel 13, is also a threaded hole with a screw groove 16 formed on its inner circumferential surface. The communicating channel 15 has a first connection port 15E1 that opens onto the inner circumferential surface of the outflow channel 13 and a second connection port 15E2 that opens onto the inner circumferential surface of the inflow channel 14, and is a channel that connects the outflow channel 13 and the inflow channel 14.

As shown in Figures 2 and 3, the ceramic substrate 10 includes a first electrode 17A and a second electrode 17B disposed inside the substrate body 11. The first electrode 17A is disposed between the communication flow path 15 and the first surface S1, and the second electrode 17B is disposed between the communication flow path 15 and the second surface S2. The first electrode 17A and the second electrode 17B are formed of a conductive material containing, for example, tungsten or molybdenum. In this embodiment, the first electrode 17A functions as a chuck electrode that exerts an electrostatic attraction force to attract the wafer W onto the first surface S1.

Most of the communicating flow path 15, excluding the portions adjacent to the outflow path 13 and inflow path 14, is sandwiched between the first electrode 17A and the second electrode 17B. The first electrode 17A and the second electrode 17B are provided at a predetermined distance from the outflow path 13 and the inflow path 14. This is because if the first electrode 17A and the second electrode 17B, made of a conductive material, were exposed to or close to the inside of the outflow path 13 or the inflow path 14, they would become the target of discharge when high-frequency power is applied.

As shown in Figures 2 and 3, the screw members 21A and 21B include a first screw member 21A disposed inside the outflow passage 13 and a second screw member 21B disposed inside the inflow passage 14. The screw members 21A and 21B are insulating and made of dense ceramics, primarily composed of, for example, aluminum nitride or alumina. The screw members 21A and 21B are solid members that do not have a hollow structure through which fluids can flow, and as shown in Figure 4, threads 22 are formed on the outer circumferential surface.

The crest 22T of the thread 22 of the first screw member 21A is parallel to the screw axis Ax of the first screw member 21A and is a plane perpendicular to the first surface S1 and the second surface S2. The groove bottom 16B of the thread groove 16 formed on the inner peripheral surface of the outlet channel 13 is a concave surface that recesses outward in an arc-like shape. This ensures a certain amount of clearance between the groove bottom 16B of the thread groove 16 and the crest 22T of the thread 22. Furthermore, chipping of the crest 22T can be prevented when the first screw member 21A is screwed. From the perspective of reducing abnormal discharge, the width WI of the crest 22T in the direction perpendicular to the first surface S1 (the distance between the edge of the crest 22T on the first surface S1 side and the edge opposite the first surface S1) is preferably 0.5 mm or less. The same applies to the thread 22 of the second screw member 21B and the thread groove 16 formed on the inner surface of the inlet channel 14.

As shown in Figures 3 and 5, an adhesive 31 is provided on the inner surface of the outflow channel 13 in a region farther from the first surface S1 than the first connection port 15E1 (the region below the first connection port 15E1 in Figures 3 and 5), filling the gap with the outer surface of the first screw member 21A. This adhesive 31 secures the first screw member 21A to the inside of the outflow channel 13. Similarly, an adhesive 31 is provided on the inner surface of the inflow channel 14 in a region farther from the second surface S2 than the second connection port 15E2 (the region above the second connection port 15E2 in Figure 3), filling the gap with the outer surface of the second screw member 21B. This adhesive 31 secures the second screw member 21B to the inside of the inflow channel 14.

[Base member 40]
1 and 3, the base member 40 is a disk-shaped member composed of a base body 41 made primarily of metal (aluminum, aluminum alloy, etc.) and an insulator 44 embedded in the base body 41. The base member 40 has a diameter larger than that of the ceramic substrate 10 and a predetermined thickness. The diameter of the base member 40 is, for example, approximately 220 mm to 550 mm (usually approximately 220 mm to 350 mm), and the thickness of the base member 40 is, for example, approximately 20 mm to 40 mm. The base member 40 has a third surface S3 facing the second surface S2 of the ceramic substrate 10, and a fourth surface S4 opposite the third surface S3.

As shown in Figures 1 and 3, the base body 41 has a refrigerant flow path 42 therein through which a refrigerant (e.g., a fluorine-based inert liquid, water, etc.) can flow. Furthermore, as shown in Figure 3, the base body 41 has an embedded hole 43 that penetrates in the thickness direction between the third surface S3 and the fourth surface S4, and an insulator 44 is embedded inside the embedded hole 43. The insulator 44 is made of, for example, insulating ceramics. The insulator 44 has a gas supply path 45 that penetrates in the thickness direction between the third surface S3 and the fourth surface S4.

As shown in FIG. 3, the base member 40 is bonded to the second surface S2 of the ceramic substrate 10 via a bonding layer 50 disposed on the third surface S3. The bonding layer 50 is made of an adhesive resin material such as a silicone-based resin, an acrylic-based resin, or an epoxy-based resin. The thickness of the bonding layer 50 is, for example, approximately 0.1 mm to 1 mm. The bonding layer 50 has a through-hole 51 that penetrates in the thickness direction and is disposed between the outflow channel 13 and the gas supply channel 45. The inner diameters of the through-hole 51 and the gas supply channel 45 are smaller than the inner diameter of the inflow channel 14.

[Suction of wafer W by holding device 1]
The holding device 1 is used, for example, as part of a semiconductor manufacturing apparatus. The holding device 1 is installed in a chamber of the semiconductor manufacturing apparatus, and a wafer W is placed on a first surface S1 of a ceramic substrate 10. When power is supplied to the first electrode 17A, which functions as a chuck electrode, electrostatic attraction is generated, and the wafer W is attracted to the first surface S1. When a source gas is introduced into the chamber and high-frequency power is applied to the base member 40, plasma is generated, and a bias voltage is generated on the wafer W, thereby processing the wafer.

When the coolant flows through the coolant flow path 42, the base member 40 is cooled, and heat transfer between the base member 40 and the ceramic substrate 10 via the bonding layer 50 cools the ceramic substrate 10, thereby cooling the wafer W held on the first surface S1 of the ceramic substrate 10. The temperature of the wafer W can be controlled by adjusting the flow of the coolant.

To adjust the temperature of the wafer W in this manner, an inert gas, such as helium gas, which serves as a heat transfer fluid, is supplied to the gas supply path 45 of the base member 40. The supplied gas flows into the gas flow path 12 of the ceramic substrate 10 through the through-holes 51, and then flows out through the outlet 13E, filling the gap G formed between the first surface S1 and the wafer W. This allows the temperature of the wafer W to be controlled with high precision.

When processing a wafer W, high-frequency power is applied to the base member 40 as described above, which may result in abnormal discharge occurring within the gas flow path 12 of the ceramic substrate 10 located between the wafer W and the base member 40. In recent years, in particular, the high-frequency power applied during plasma processing has become higher voltage in order to speed up processing, increasing the potential difference between the wafer W and the base member 40 and increasing the likelihood of abnormal discharge occurring within the gas flow path 12.

Of the gas flow paths 12, the majority of the communication paths 15 are sandwiched between the first electrode 17A and the second electrode 17B, reducing the occurrence of abnormal discharge in the area sandwiched between these electrodes 17A and 17B. However, since electrodes 17A and 17B cannot be placed above and below the outlet path 13 and inlet path 14, abnormal discharge is more likely to occur.

In this embodiment, the outlet channel 13 is a threaded hole with a screw groove 16 formed on its inner circumferential surface, and a first screw member 21A is disposed inside. Gas can flow through the gap between the inner circumferential surface of the outlet channel 13 and the outer circumferential surface of the first screw member 21A. This gap is a space that extends spirally along the spiral shape of the screw groove 16 and the screw thread 22. Therefore, the size of the void space inside the gas flow channel 12 extending from the wafer W toward the base member 40 (i.e., perpendicular to the first surface S1), where abnormal discharge is likely to occur, can be minimized. The same applies to the inlet channel 14 and the second screw member 21B. This reduces the occurrence of abnormal discharge within the gas flow channel 12 without impeding the supply of gas.

[Action and effect]
As described above, according to this embodiment, the holding device 1 includes a ceramic substrate 10 having a first surface S1 for holding a wafer W, a second surface S2 located opposite the first surface S1, and a gas flow path 12 having an outlet 13E opening at the first surface S1 and an inlet 14E opening at the second surface S2, through which a gas can flow. A portion of the gas flow path 12 adjacent to the outlet 13E has a thread groove 16 on its inner circumferential surface and forms an outlet path 13 extending perpendicular to the first surface S1, while a portion of the gas flow path 12 adjacent to the inlet 14E has a thread groove 16 on its inner circumferential surface and forms an inlet path 14 extending perpendicular to the first surface S1. The ceramic substrate 10 further includes a first solid screw member 21A and a second solid screw member 21B having a thread 22 on its outer circumferential surface and screwed into the outlet path 13 and the inlet path 14, respectively. Gas can flow through the gap between the inner surface of the outlet passage 13 and the outer surface of the first screw member 21A, and through the gap between the inner surface of the inlet passage 14 and the outer surface of the second screw member 21B.

With the above configuration, the gap between the inner surface of the outlet channel 13 and the outer surface of the first screw member 21A, and the gap between the inner surface of the inlet channel 14 and the outer surface of the second screw member 21B are spaces that extend spirally along the screw groove 16 and the thread 22. This minimizes the size of the void space extending perpendicular to the first surface S1 inside the gas flow channel 12, where abnormal discharge is likely to occur. This reduces the occurrence of abnormal discharge within the gas flow channel 12 without impeding the supply of gas.

The gas flow path 12 also has an outlet path 13 adjacent to the outlet 13E, an inlet path 14 adjacent to the inlet 14E, and a communication path 15 connecting the two. In this configuration, the outlet path 13 and the inlet path 14 are threaded holes, and screw members 21A and 21B are disposed in these holes, thereby reducing the occurrence of abnormal discharge within the gas flow path 12.

In addition, the crest 22T of the thread 22 is a surface parallel to the screw axis Ax of the screw members 21A and 21B, and the groove bottom surface 16B of the thread groove 16 is a concave surface. This configuration ensures a gap between the groove bottom surface 16B of the thread groove 16 and the crest 22T of the thread 22 through which gas can flow.

<Modification 1>
The retaining device 60 of the first modification example differs from the first embodiment in that, as shown in FIG. 6 , a portion of the first screw member 62 provided on the ceramic substrate 61 is arranged inside a through hole 64 of the bonding layer 63.

The bonding layer 63 provided in the holding device 60 of this modified example has an inner diameter approximately equal to the inner diameter of the inlet channel 14 and has a through hole 64 communicating with the inlet channel 14 and the gas supply channel 45. The first screw member 62 has a configuration similar to that of the first screw member 21A of embodiment 1, except for its length. More specifically, the first screw member 62 has a length equivalent to the sum of the length of the inlet channel 14 (the distance between the inner end of the inlet channel 14 opposite the second surface S2 and the second surface S2) and the length of the through hole 64 (the distance between the surface of the bonding layer 63 that contacts the second surface S2 and the surface that contacts the third surface S3), and one end (the lower end in FIG. 6 ) is disposed within the through hole 64. A gap through which gas can flow is secured between the inner circumferential surface of the through hole 64 and the outer circumferential surface of the first screw member 62. Other configurations are similar to those of embodiment 1, and therefore, the same components as those of embodiment 1 are designated by the same reference numerals and will not be described again.

As with embodiment 1, this modified example also reduces the occurrence of abnormal discharge within the gas flow path 12 without interfering with the supply of gas. In addition, by arranging one end of the first screw member 62 inside the through hole 64, abnormal discharge within the through hole 64 can be reduced.

<Embodiment 2>
The holding device 70 of the second embodiment differs from that of the first embodiment in the configuration of the gas flow path 73. The ceramic substrate 71 provided in the holding device 70 of the present embodiment includes a disk-shaped substrate body 72 and a screw member 75 attached to the substrate body 72, as shown in FIG.

The substrate body 72 has a gas flow path 73 through which gas can flow, with an outlet 73E1 opening on the first surface S1 and an inlet 73E2 opening on the second surface S2. The gas flow path 73 extends from the outlet 73E1 perpendicular to the first surface S1 to the inlet 73E2. The gas flow path 73 is a threaded hole with a thread groove 74 formed on its inner circumferential surface along its entire length. A screw member 75 is disposed inside the gas flow path 73. As in embodiment 1, the screw member 75 is a solid member without a hollow structure through which fluids can flow, and has a thread 76 formed on its outer circumferential surface. Although not shown in detail, as in embodiment 1, the top of the thread 76 is preferably parallel to the screw axis of the screw member 75, and the bottom of the thread groove 74 is preferably concave.

The length of the screw member 75 is slightly shorter than the length of the gas flow path 73 (the distance between the first surface S1 and the second surface S2), and there is a gap between the surface of the bonding layer 50 and one end of the screw member 75 (the lower end in Figure 7 ) through which gas can flow. As shown in Figure 8 , adhesive 77 is provided at multiple locations (two locations in this embodiment) spaced apart circumferentially on the inner surface of the gas flow path 73 to fill the gap between the inner surface and the outer surface of the screw member 75.

As in embodiment 1, the bonding layer 50 and the base member 40 each have a through hole 51 and a gas supply channel 45. The inner diameters of the through hole 51 and the gas supply channel 45 are smaller than the inner diameter of the gas flow channel 73.

Other configurations are the same as in embodiment 1, so the same components as in embodiment 1 are given the same reference numerals and descriptions are omitted.

In this embodiment, as in embodiment 1, the occurrence of abnormal discharge within the gas flow path 73 can be reduced without interfering with the supply of gas.

The inner diameter of the through hole 51 is also smaller than the inner diameter of the gas flow path 73. In this configuration, if one end (the lower end in Figure 7) of the screw member 75 were to contact the surface of the bonding layer 50, the inlet portion through which gas flows into the gap between the inner surface of the gas flow path 73 and the outer surface of the screw member 75 would be blocked by the bonding layer 50. However, in this embodiment, because there is a gap between the surface of the bonding layer 50 and the screw member 75, a space is secured inside the through hole 51 for gas supplied from the gas supply path 45 to flow into the gap between the inner surface of the gas flow path 73 and the outer surface of the screw member 75.

In addition, adhesive 77 for fixing the screw member 75 to the inside of the gas flow path 73 is arranged in two locations spaced apart in the circumferential direction. This prevents the screw member 75 from falling off while ensuring a gap between the inner surface of the gas flow path 73 and the screw member 75 through which gas can flow.

<Modification 2>
The holding device 80 of the modified example 2 differs from the embodiment 2 in that, as shown in Figure 9, a portion of the screw member 82 provided on the ceramic substrate 81 is arranged inside a through hole 84 provided in the bonding layer 83.

The bonding layer 83 provided in the holding device 80 of this modified example has an inner diameter that is approximately equal to the inner diameter of the gas flow path 73 and larger than the inner diameter of the gas supply path 45, and has a through hole 84 that communicates with the gas flow path 73 and the gas supply path 45.

The screw member 82 has a similar configuration to the screw member 75 of embodiment 2, except for its length. More specifically, the length of the screw member 82 is slightly longer than the length of the gas flow path 73 and slightly shorter than the combined length of the gas flow path 73 and the through hole 84 (the distance between the surface of the bonding layer 83 that contacts the second surface S2 and the surface that contacts the third surface S3), and one end (the lower end in Figure 9) of the screw member 82 is disposed inside the through hole 84. A gap is provided between the inner circumferential surface of the through hole 84 and the outer circumferential surface of the screw member 82, allowing gas to flow through. A gap is provided between the surface of the base member 40 and one end (the lower end in Figure 9) of the screw member 82, allowing gas to flow in.

Other configurations are the same as in embodiment 2, so the same components as in embodiment 2 are designated by the same reference numerals and their explanations are omitted.

In this embodiment, as in embodiments 1 and 2, the occurrence of abnormal discharge within the gas flow path 73 can be reduced without interfering with the supply of gas.

The inner diameter of the gas supply path 45 is smaller than the inner diameters of the gas flow path 73 and the through hole 84. With this configuration, if one end of the screw member 82 were to contact the surface of the base member 40, the inlet portion through which gas flows into the gap between the inner surface of the gas flow path 73 and the outer surface of the screw member 82 would be blocked by the base member 40. However, in this modified example, because there is a gap between the surface of the base member 40 and the screw member 82, space is secured inside the through hole 84 for gas supplied from the gas supply path 45 to flow into the gap between the inner surface of the through hole 84 and the outer surface of the screw member 82.

<Other Embodiments>
(1) In the above embodiment and modified examples, the screw members 21A, 21B, 62, 75, 82 are fixed to the substrate main body 11, 72 by the adhesive 31, 77, but the screw members do not have to be fixed by an adhesive.
(2) In the second embodiment and the second modification, the adhesive 77 is applied in two locations. However, the adhesive may be applied in three or more locations spaced apart in the circumferential direction.
(3) The present disclosure is not limited to the electrostatic chuck exemplified in the above embodiment, but can also be similarly applied to other holding devices (e.g., heating devices) that hold an object on the surface of a ceramic substrate.
(4) In the above embodiment, high-frequency power was applied to the base member 40. However, the technology disclosed in this specification can also be applied when high-frequency power is applied to an electrode provided on a ceramic substrate.
(5) In the above embodiment, the first electrode 17A and the second electrode 17B sandwich most of the communicating flow path, and the first electrode 17A serves as a chuck electrode. However, a chuck electrode may be provided separately from the electrodes sandwiching most of the communicating flow path (for example, closer to the first surface S1 than the first electrode 17A).
(6) In the above embodiment, one end (the lower end in FIG. 3 ) of the first screw member 21A disposed inside the outflow channel 13 was embedded in a region of the ceramic substrate 10 that was farther from the first surface S1 than the first connection port 15E1 (a region below the communicating flow path 15 in FIG. 3 ). However, the screw member may be disposed in a region closer to the first surface than the communicating flow path and inside the communicating flow path, but not in a region farther from the first surface S1 than the communicating flow path. Alternatively, the screw member may be disposed only in a region closer to the first surface than the communicating flow path, but not in the communicating flow path or in a region farther from the first surface than the communicating flow path. In the above embodiment, one end (upper end in FIG. 3 ) of the second screw member 21B disposed inside the inlet channel 14 was embedded in a region of the ceramic substrate 10 closer to the first surface S1 than the first connection port 15E1 (a region above the communicating flow channel 15 in FIG. 3 ), but the screw member may be disposed in a region farther from the first surface than the communicating flow channel and inside the communicating flow channel, but not in a region closer to the first surface S1 than the communicating flow channel. Alternatively, the screw member may be disposed only in a region farther from the first surface than the communicating flow channel, but not in the communicating flow channel or in a region closer to the first surface than the communicating flow channel.
(7) In the above embodiment, the crests 22T of the threads 22 of the screw members 21A and 21B are flat surfaces parallel to the screw axis Ax. However, the crests of the threads of the screw members may not be flat surfaces and may have a pointed shape. If the crests of the threads are pointed, the size of the void extending perpendicular to the first surface, where abnormal discharge is likely to occur, can be minimized.

1, 60, 70, 80: Holding device 10, 61, 71, 81: Ceramic substrate (plate-shaped member)
11, 72: Substrate body 12: Gas flow path 13: Outlet path (screw hole, first screw hole)
13E, 73E1: Outlet 14: Inlet channel (threaded hole, second threaded hole)
14E, 73E2: inlet 15: communication flow path 15E1: first connection port 15E2: second connection port 16, 74: screw groove 16B: groove bottom surface 17A: first electrode 17B: second electrode 21A, 62: first screw member (screw member)
21B: Second screw member (screw member)
22, 76: thread 22T: top 31, 77: adhesive 40: base member 41: base body 42: coolant flow path 43: embedded hole 44: insulator 45: gas supply path 50, 63, 83: bonding layer 51, 64: through hole 73: gas flow path (threaded hole)
75, 82: screw member Ax: screw shaft G: gap S1: first surface S2: second surface S3: third surface S4: fourth surface W: wafer WI: width of top

Claims (6)

A holding device comprising a plate-like member having a first surface for holding an object, a second surface located opposite to the first surface, and a gas flow path having an outlet opening in the first surface and an inlet opening in the second surface, through which a gas can flow,
At least a portion of the gas flow path adjacent to the outlet or the inlet has a thread groove on an inner circumferential surface and a threaded hole extending in a direction perpendicular to the first surface,
the plate-like member further includes a solid screw member having a screw thread on an outer circumferential surface thereof and being screwed into the screw hole;
the gas can flow through a gap between the inner circumferential surface of the screw hole and the outer circumferential surface of the screw member ,
the gas flow path includes a first threaded hole adjacent to the outlet, a second threaded hole adjacent to the inlet, a first connection port opening on the inner circumferential surface of the first threaded hole, and a second connection port opening on the inner circumferential surface of the second threaded hole, and a communication flow path that communicates the first threaded hole with the second threaded hole,
A retention device , wherein a first of the threaded members is disposed within the first threaded hole and a second of the threaded members is disposed within the second threaded hole . 2. The retaining device of claim 1, wherein an adhesive is disposed in an area of the inner surface of the first screw hole that is farther from the first surface than the first connection port, and in an area of the inner surface of the second screw hole that is farther from the second surface than the second connection port, to fill the gap between the outer surfaces of the first screw member and the second screw member. A holding device comprising a plate-like member having a first surface for holding an object, a second surface located opposite to the first surface, and a gas flow path having an outlet opening in the first surface and an inlet opening in the second surface, through which a gas can flow,
At least a portion of the gas flow path adjacent to the outlet or the inlet has a thread groove on an inner circumferential surface and a threaded hole extending in a direction perpendicular to the first surface,
the plate-like member further includes a solid screw member having a screw thread on an outer circumferential surface thereof and being screwed into the screw hole;
the gas can flow through a gap between the inner circumferential surface of the screw hole and the outer circumferential surface of the screw member,
the gas flow path is a threaded hole extending from the outlet perpendicular to the first surface to the inlet;
a base member bonded to the second surface via an adhesive bonding layer;
the bonding layer has a through hole that is in communication with the outflow port and has an inner diameter smaller than that of the outflow port,
the base member has a gas supply passage communicating with the through hole,
a gap is formed between the surface of the joining layer and the screw member;
A retaining device in which an adhesive is provided at multiple locations spaced apart in the circumferential direction on the inner surface of the screw hole to fill gaps between the inner surface and the outer surface of the screw member. A holding device comprising a plate-like member having a first surface for holding an object, a second surface located opposite to the first surface, and a gas flow path having an outlet opening in the first surface and an inlet opening in the second surface, through which a gas can flow,
At least a portion of the gas flow passage adjacent to the outlet or the inlet has a thread groove on an inner circumferential surface and a threaded hole extending in a direction perpendicular to the first surface,
the plate-like member further includes a solid screw member having a screw thread on an outer circumferential surface thereof and being screwed into the screw hole;
the gas can flow through a gap between the inner circumferential surface of the screw hole and the outer circumferential surface of the screw member,
the gas flow path is a threaded hole extending from the outlet perpendicular to the first surface to the inlet;
a base member bonded to the second surface via an adhesive bonding layer;
the bonding layer has a through hole communicating with the outlet,
the base member has a gas supply passage that is in communication with the through hole and has an inner diameter smaller than that of the through hole;
a part of the screw member is disposed inside the through hole, and the gas can flow through a gap between an inner peripheral surface of the through hole and an outer peripheral surface of the screw member;
a gap is provided between the surface of the base member and the screw member;
A retaining device in which an adhesive is applied at multiple locations circumferentially spaced apart on the inner surface of the through hole to fill gaps between the inner surface of the through hole and the outer surface of the screw member. 5. The retaining device according to claim 1 , wherein the crest of the screw thread is a surface parallel to the screw axis of the screw member, and the bottom surface of the screw groove is a concave surface. A holding device comprising a plate-like member having a first surface for holding an object, a second surface located opposite to the first surface, and a gas flow path having an outlet opening in the first surface and an inlet opening in the second surface, through which a gas can flow,
At least a portion of the gas flow path adjacent to the outlet or the inlet has a thread groove on an inner circumferential surface and a threaded hole extending in a direction perpendicular to the first surface,
the plate-like member further includes a solid screw member having a screw thread on an outer circumferential surface thereof and being screwed into the screw hole;
the gas can flow through a gap between the inner circumferential surface of the screw hole and the outer circumferential surface of the screw member,
the gas flow path includes an outlet path adjacent to the outlet, an inlet path adjacent to the inlet, and a communication path connecting the outlet path and the inlet path,
the communication channel is formed in a direction parallel to the first surface,
A holding device, wherein at least one of the outlet passage or the inlet passage has the screw groove on an inner circumferential surface and has the screw hole extending in the vertical direction.