electrostatic chuck

Abstract

The present invention provides an electrostatic chuck that can be easily manufactured, while having a configuration in which the internal electrodes of a dielectric substrate and the base plate are electrically connected by a conductive material. [Solution] The electrostatic chuck 10 comprises a dielectric substrate 100, an RF electrode 140 provided inside the dielectric substrate 100, a base plate 200 made of metal and bonded to the dielectric substrate 100, and a conductive member 400 that electrically connects the RF electrode 140 and the base plate 200. A first recess 160 is formed on the surface 120 of the dielectric substrate 100 facing the base plate 200, which accommodates a part of the conductive member 400. A second recess 260 is formed on the surface 210 of the base plate 200 facing the dielectric substrate 100, which accommodates a part of the conductive member 400. In a top view, one of the first recess 160 and the second recess 260 is larger than the other.

Description

Technical Field

[0001] The present invention relates to an electrostatic chuck.

Background Art

[0002] For example, in a semiconductor manufacturing apparatus such as an etching apparatus, an electrostatic chuck is provided as a device for adsorbing and holding a substrate such as a silicon wafer to be processed. The electrostatic chuck includes a dielectric substrate provided with an adsorption electrode and a base plate for supporting the dielectric substrate, and these are joined to each other. When a voltage is applied to the adsorption electrode, an electrostatic force is generated, and the substrate placed on the dielectric substrate is adsorbed and held.

[0003] As described in Patent Document 1 below, the dielectric substrate may incorporate an RF electrode, which is one of a pair of opposing electrodes for generating plasma in a semiconductor manufacturing apparatus. In this case, the RF electrode and the base plate are electrically connected via a conductive member. Thereby, the potential of the RF electrode during substrate processing is maintained at the potential of the base plate (for example, the ground potential).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] To electrically connect a conductive member and an RF electrode, for example, a recess can be formed on the base plate side of the dielectric substrate, the RF electrode can be exposed at its bottom, and the conductive member can be housed inside the recess. Similarly, to electrically connect a conductive member and a base plate, for example, a recess can be formed on the dielectric substrate side of the base plate, and the conductive member can be housed inside the recess. In this case, a portion of the conductive member will be housed in the recess of the dielectric substrate, and another portion will be housed in the recess of the base plate.

[0006] When manufacturing an electrostatic chuck with this configuration, for example, with the surface of the base plate where the recesses are formed facing upwards, a portion of the conductive member is inserted into each recess, causing the conductive member to protrude vertically from the top surface of the base plate. Then, by bringing the surface of the dielectric substrate where the recesses are formed (bottom surface) closer to the surface of the base plate where the recesses are formed (top surface) and joining the two together, the conductive member can be housed inside each recess.

[0007] In this case, if the gap between the recess in the dielectric substrate and the conductive member is too small, it becomes difficult to align the components when performing the bonding as described above. Also, if the gap between the recess in the base plate and the conductive member is too large, it becomes difficult to position the conductive member so that it protrudes vertically from the top surface of the base plate. Furthermore, since the position of the conductive member in this state is not fixed, it also becomes difficult to align the components when performing the bonding. The same problems as above can occur when performing bonding by placing the electrostatic chuck on the lower side and approaching the base plate from above.

[0008] This invention has been made in view of these problems, and its objective is to provide an electrostatic chuck that can be easily manufactured, while having a configuration in which the internal electrodes of a dielectric substrate and a base plate are electrically connected by a conductive member. [Means for solving the problem]

[0009] To solve the above problems, the electrostatic chuck according to the present invention comprises a dielectric substrate having a mounting surface on which an object to be adsorbed is placed, an internal electrode provided inside the dielectric substrate, a base plate made of metal and bonded to the dielectric substrate, and a conductive member that electrically connects the internal electrode and the base plate. A first recess for accommodating a part of the conductive member is formed on the base plate side of the dielectric substrate, and a second recess for accommodating a part of the conductive member is formed on the dielectric substrate side of the base plate. When viewed from a direction perpendicular to the mounting surface, one of the first recess and the second recess is larger than the other.

[0010] When joining a dielectric substrate and a base plate, the component with the smaller of the two recesses (first and second recesses) is placed on the lower side, a portion of the conductive member is inserted into the recess, and then the component with the larger of the two recesses is brought closer from above. In the lower component, a portion of the conductive member is inserted into a relatively small recess, preventing the conductive member from tilting or shifting. In the upper component, a relatively large recess is formed, so when bringing this component closer to the lower component, a portion of the conductive member can be easily accommodated in that recess. In this way, with the electrostatic chuck configured above, by making the sizes of the first and second recesses different when viewed from above, the joining work during manufacturing can be made easier than in conventional methods. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an electrostatic chuck that can be easily manufactured, while having a configuration in which the internal electrodes of the dielectric substrate and the base plate are electrically connected by a conductive member. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic cross-sectional view showing the configuration of the electrostatic chuck according to the first embodiment. [Figure 2] This is a cross-sectional view showing in detail the configuration of the conductive member and its vicinity in the electrostatic chuck according to the first embodiment. [Figure 3] This is a perspective view showing the configuration of the conductive component. [Figure 4] This is a diagram illustrating a method for manufacturing an electrostatic chuck according to the first embodiment. [Figure 5] This is a cross-sectional view showing in detail the configuration of the conductive member and its vicinity in the electrostatic chuck according to the second embodiment. [Figure 6] This is a cross-sectional view showing in detail the configuration of the conductive member and its vicinity in the electrostatic chuck according to the third embodiment. [Figure 7] This is a diagram illustrating a method for manufacturing an electrostatic chuck according to the third embodiment. [Figure 8] This is a cross-sectional view showing in detail the configuration of the conductive member and its vicinity in the electrostatic chuck according to the fourth embodiment. [Modes for carrying out the invention]

[0013] This embodiment will now be described with reference to the attached drawings. To facilitate understanding of the explanation, the same reference numerals are used for identical components in each drawing whenever possible, and redundant explanations are omitted.

[0014] A first embodiment will be described. The electrostatic chuck 10 according to this embodiment is used to attract and hold a substrate W to be processed by electrostatic force inside a semiconductor manufacturing apparatus (not shown), such as an etching apparatus. The substrate W to be attracted is, for example, a silicon wafer. The electrostatic chuck 10 may also be used in apparatus other than semiconductor manufacturing apparatus.

[0015] Figure 1 shows a schematic cross-sectional view of the electrostatic chuck 10 in a state where the substrate W is adsorbed and held. The electrostatic chuck 10 comprises a dielectric substrate 100 and a base plate 200.

[0016] The dielectric substrate 100 is a substantially disc-shaped member made of a ceramic sintered body. The dielectric substrate 100 contains, for example, high-purity aluminum oxide (Al2O3), but may contain other materials. The purity, type, additives, etc. of the ceramics in the dielectric substrate 100 can be appropriately set in consideration of the plasma resistance required for the dielectric substrate 100 in the semiconductor manufacturing apparatus.

[0017] Among the dielectric substrate 100, the upper surface 110 in FIG. 1 is the "placement surface" on which the substrate W is placed. Also, the lower surface 120 of the dielectric substrate 100 in FIG. 1 is the "bonding surface" that is bonded to the base plate 200 via the bonding layer 300. The direction along the direction perpendicular to the surface 110 and the viewpoint when viewing the electrostatic chuck 10 from the surface 110 side will also be hereinafter referred to as "top view".

[0018] An adsorption electrode 130 is embedded inside the dielectric substrate 100. The adsorption electrode 130 is, for example, a thin flat plate-shaped layer formed of a metal material such as tungsten and is arranged to be parallel to the surface 110. As the material of the adsorption electrode 130, in addition to tungsten, molybdenum, platinum, palladium, etc. may also be used. When a voltage is applied to the adsorption electrode 130 from the outside via a power supply path (not shown), an electrostatic force is generated between the surface 110 and the substrate W, and thereby the substrate W is adsorbed and held. As the configuration of the above power supply path, various known configurations can be adopted. The adsorption electrode 130 may be provided only one as a so-called "unipolar" electrode as in this embodiment, or may be provided two as a so-called "bipolar" electrode.

[0019] Inside the dielectric substrate 100, in addition to the above-described adsorption electrode 130, an RF electrode 140 is also embedded. The RF electrode 140 is provided as one of a pair of opposing electrodes for generating plasma in a semiconductor manufacturing apparatus. The other of the opposing electrodes is provided at a position above the electrostatic chuck 10 in the semiconductor manufacturing apparatus. When a high-frequency alternating voltage is applied between these opposing electrodes, plasma is generated above the substrate W and is used for processes such as film formation and etching on the substrate W. The RF electrode 140 corresponds to the "internal electrode" in the present embodiment.

[0020] The RF electrode 140 is, like the adsorption electrode 130, a thin flat plate-shaped layer formed of a metal material such as tungsten, for example. As the material of the RF electrode 140, in addition to tungsten, molybdenum, platinum, palladium, etc. may also be used. The RF electrode 140 is embedded at a position closer to the surface 120 side than the adsorption electrode 130. The RF electrode 140 is arranged parallel to the surface 110, like the adsorption electrode 130. The RF electrode 140 is a single electrode that is substantially circular in a top view. The center of the RF electrode 140 in a top view coincides with the center of the dielectric substrate 100.

[0021] A conductive member 400 is provided on the electrostatic chuck 10. The conductive member 400 is a member for electrically connecting between the RF electrode 140 and a base plate 200 described later. Due to the conductive member 400, the potential of the RF electrode 140 during the processing of the substrate W becomes the same as the potential of the base plate 200. In FIG. 1, the conductive member 400 is schematically drawn as a simple straight line. The specific shape of the conductive member 400 will be described later.

[0022] As shown in Figure 1, a space SP is formed between the dielectric substrate 100 and the substrate W. When etching or other processes are performed in the semiconductor manufacturing apparatus, helium gas for temperature control is supplied to the space SP from the outside through a gas hole (not shown). By interposing helium gas between the dielectric substrate 100 and the substrate W, the thermal resistance between them is adjusted, thereby maintaining the temperature of the substrate W at an appropriate temperature. Note that the gas supplied to the space SP for temperature control may be a different type of gas than helium.

[0023] A sealing ring 111 and dots 112 are provided on the mounting surface 110, and the above-mentioned space SP is formed around them.

[0024] The seal ring 111 is a wall that demarcates the space SP at its outermost position. The seal ring 111 is an annular projection formed on the surface 110 side. The tip of the seal ring 111 (the upper end in Figure 1) is part of the surface 110 and contacts the substrate W. The tip of the seal ring 111 can be said to be the outermost part of the mounting surface 110.

[0025] Furthermore, multiple seal rings 111 may be provided to divide the space SP. With this configuration, the pressure of the helium gas in each space SP can be individually adjusted, making the surface temperature distribution of the substrate W during processing more uniform.

[0026] In Figure 1, the portion labeled "116" is the bottom surface of the space SP. Hereafter, this portion will also be referred to as "bottom surface 116". The seal ring 111, along with the dot 112 described below, is formed as a result of excavating a portion of the surface 110 down to the position of the bottom surface 116.

[0027] The dots 112 are circular protrusions that extend from the bottom surface 116. Multiple dots 112 are provided and are distributed approximately evenly on the mounting surface of the dielectric substrate 100. The tip of each dot 112 is part of the surface 110 and contacts the substrate W. By providing multiple such dots 112, the bending of the substrate W is suppressed.

[0028] The base plate 200 is a substantially disc-shaped member that supports the dielectric substrate 100. The base plate 200 is made of a metallic material such as aluminum. The base plate 200 is bonded to the surface 120 of the dielectric substrate 100 via a bonding layer 300. Of the base plate 200, the upper surface 210 in Figure 1 is the "bonded surface" that is bonded to the dielectric substrate 100.

[0029] The bonding layer 300 is a layer provided between the dielectric substrate 100 and the base plate 200, and it bonds the two together. The bonding layer 300 is made by curing an adhesive made of an insulating material. In this embodiment, a silicone adhesive is used as the adhesive. However, the bonding layer 300 may be made by curing another type of adhesive. In any case, it is preferable to use a material with the highest possible thermal conductivity for the bonding layer 300 so that the thermal resistance between the dielectric substrate 100 and the base plate 200 is reduced.

[0030] An insulating film may be formed on the surface of the base plate 200. As the insulating film, for example, an alumina film formed by thermal spraying can be used. By covering the surface of the base plate 200 with an insulating film, the dielectric strength of the base plate 200 can be increased.

[0031] A refrigerant channel 250 is formed inside the base plate 200 for passing a refrigerant. When etching or other processes are performed in the semiconductor manufacturing equipment, a refrigerant is supplied from the outside to the refrigerant channel 250, thereby cooling the base plate 200. During processing, the heat generated in the substrate W is transferred to the refrigerant via the helium gas in the space SP, the dielectric substrate 100, and the base plate 200, and is discharged to the outside together with the refrigerant. The supply and discharge of refrigerant to and from the refrigerant channel 250 is performed through an opening (not shown) formed on the surface 220 of the base plate 200 opposite to the surface 210.

[0032] The specific configuration of the conductive member 400 and its vicinity will be described with reference to Figure 2. As shown in the figure, a first recess 160 is formed on the surface 120 of the dielectric substrate 100 on the base plate 200 side. The first recess 160 is a portion of the surface 120 that has been recessed toward the surface 110 in order to allow the conductive member 400 to be placed therein. In this embodiment, the first recess 160 is formed to a depth position that exposes the RF electrode 140. Therefore, the RF electrode 140, which is an internal electrode, is exposed at the bottom surface 162 of the first recess 160. In a top view, the shape of the first recess 160 is circular, and a substantially cylindrical space is formed inside it.

[0033] A second recess 260 is formed on the surface 210 of the base plate 200 that faces the dielectric substrate 100. The second recess 260 is formed on the surface 210 in the portion that overlaps with the first recess 160 when viewed from above. The second recess 260 is a portion of the surface 210 that has been recessed toward the surface 220 in order to allow the conductive member 400 to be placed therein. The metal portion of the base plate 200 is exposed throughout the inside of the second recess 260. The shape of the second recess 260 when viewed from above is circular, and a roughly cylindrical space is formed inside it. The central axis of the second recess 260 coincides with the central axis of the first recess 160. However, the diameter of the inner circumferential surface 261 of the second recess 260 is smaller than the diameter of the inner circumferential surface 161 of the first recess 160.

[0034] A circular opening is formed in the joint layer 300 between the first recess 160 and the second recess 260. The first recess 160 and the second recess 260 are connected through this opening, and the entire area forms a single space.

[0035] In Figure 2, the component labeled "310" is a component positioned to prevent uncured adhesive from seeping into the first recess 160 and the second recess 260. This component will also be referred to as the "blocking portion 310" below. In a top view, the blocking portion 310 is an annular component positioned to surround the first recess 160 from the outside all around. The inner diameter of the blocking portion 310 is the same as the inner diameter of the first recess 160, but it may be a different size. For example, cured silicone adhesive can be used as the blocking portion 310.

[0036] The conductive member 400 is a substantially cylindrical member formed from a fibrous metal member and is housed inside the first recess 160 and the second recess 260. In other words, a portion of the conductive member 400 is housed in the first recess 160, and another portion of the conductive member 400 is housed in the second recess 260. In a top view, the diameter of the portion of the conductive member 400 housed in the first recess 160 is equal to the diameter of the portion of the conductive member 400 housed in the second recess 260.

[0037] The conductive member 400 is in contact with the RF electrode 140, which is exposed at the bottom surface 162 of the first recess 160. The conductive member 400 is also in contact with the metal portion of the base plate 200, which is exposed at the bottom surface 262 of the second recess 260. The conductive member 400, positioned in this manner, electrically connects the RF electrode 140 and the metal portion of the base plate 200.

[0038] As shown in Figure 3, the conductive member 400 has a substantially cylindrical main body portion 410 and a plurality of protrusions 420, and the entire body is integrally formed from a fibrous metal member. The protrusions 420 are substantially cylindrical projections formed so as to extend from the surface of the main body portion 410 facing the dielectric substrate 100, and further toward the dielectric substrate 100. In this embodiment, a total of four protrusions 420 are formed, but the number of protrusions 420 may be different.

[0039] The conductive member 400, which is made of fibrous metal material, has enough permeability to allow fluids such as air and adhesives to enter its interior. In other words, the fibrous metal material is not sufficiently dense, and there are gaps between the fibers. With this configuration, each part of the conductive member 400, including the protrusions 420, is an elastic body that can be easily deformed by external forces.

[0040] When no external force is being applied, the vertical dimension of the conductive member 400 (in the direction in which the protrusions 420 extend) is larger than the dimension in the same direction in the state shown in Figure 2. In other words, the conductive member 400 is compressed along the direction from the dielectric substrate 100 toward the base plate 200, housed inside the first recess 160 and the second recess 260, and sandwiched between the RF electrode 140 and the base plate 200. The tip of each protrusion 420 is elastically deformed so as to be crushed by being pressed against the bottom surface 162 of the first recess 160 (i.e., the RF electrode 140).

[0041] The conductive member 400 is pressed against the RF electrode 140 and the base plate 200 by its own restoring force. Therefore, even if thermal expansion or contraction occurs in various parts of the electrostatic chuck 10 during processing of the substrate W, the electrical connection between the RF electrode 140 and the base plate 200 is always maintained.

[0042] The number of conductive members 400 may be one or more. For example, spaces consisting of the first recess 160 and the second recess 260 may be formed in a manner that is arranged in a plurality along the circumferential direction, with one conductive member 400 housed in each space.

[0043] The conductive member 400 may have a different shape than that of this embodiment. For example, the conductive member 400 may be substantially cylindrical in shape and may not have a protruding portion 420.

[0044] The method for joining the dielectric substrate 100 and the base plate 200 in the manufacturing method of the electrostatic chuck 10 will be explained with reference to Figure 4. In Figure 4, the configurations of the dielectric substrate 100, the base plate 200, and the conductive member 400 are depicted in a simplified and schematic manner.

[0045] First, the base plate 200 is placed on a workbench (not shown) with its surface 210 facing upwards. A second recess 260 is pre-formed on surface 210. In addition, an adhesive that will become a bonding layer 300 after curing is pre-applied to substantially the entire surface 210. In Figure 4, the illustration of the adhesive is omitted. The adhesive may also be pre-applied to surface 120 of the dielectric substrate 100.

[0046] Next, the conductive members 400 are inserted into each of the second recesses 260. As shown in Figure 4, each conductive member 400 protrudes vertically from the surface 210 of the base plate 200.

[0047] Next, the dielectric substrate 100 is brought closer to the surface 210 from above, with the surface 120 facing downwards. A first recess 160 is pre-formed on the surface 120. The dielectric substrate 100 and the base plate 200 are aligned with each other so that each first recess 160 is directly above each second recess 260. The dielectric substrate 100 is moved along the arrows in Figure 4 and bonded to the base plate 200. Once the movement is complete, each conductive member 400 is housed inside the first recess 160 and the second recess 260. Then, the entire assembly is heated to cure the adhesive, completing the electrostatic chuck 10 shown in Figure 1.

[0048] If the inner diameter of the first recess 160 formed in the dielectric substrate 100 were smaller than the inner diameter in this embodiment, for example, if it were about the same as the inner diameter of the second recess 260, then aligning the dielectric substrate 100 when moving it closer to the base plate 200 on the lower side would become difficult. In other words, it would become difficult to get each conductive member 400 inside the first recess 160. Therefore, in this embodiment, the inner diameter of the first recess 160 is made larger than the inner diameter of the second recess 260. This makes it possible to easily get each conductive member 400 inside the first recess 160 while moving the dielectric substrate 100 downwards.

[0049] Furthermore, if the inner diameter of the second recess 260 formed in the base plate 200 is larger than the inner diameter in this embodiment, the gap between the inner circumferential surface 261 of the second recess 260 and the conductive member 400 will increase, making it difficult to position the conductive member 400 so that it protrudes vertically from the surface 210 of the base plate 200. Also, since the position of the conductive member 400 in this state cannot be precisely determined, it becomes difficult to align the dielectric substrate 100 when bringing it closer to the lower base plate 200. Therefore, in this embodiment, the inner diameter of the second recess 260 is made smaller than the inner diameter of the first recess 160, and is about the same size as the outer diameter of the conductive member 400. Since a part of the conductive member 400 is inserted into the relatively small second recess 260, tilting and displacement of the conductive member 400 are prevented. As a result, the above joining work during the manufacturing of the electrostatic chuck 10 can be easily performed.

[0050] Incidentally, since the conductive member 400 is a metallic component, its thermal conductivity is relatively high. Therefore, during processing of the substrate W, the portion of the dielectric substrate 100 near the conductive member 400 may be excessively cooled by the base plate 200 via the conductive member 400. Furthermore, if the amount of heat generated by the conductive member 400 increases due to the application of current to the RF electrode 140, the portion of the dielectric substrate 100 near the conductive member 400 may be excessively heated by the conductive member 400. Such localized cooling or heating by the conductive member 400 is considered to be particularly likely to occur when the inner circumferential surface 161 of the first recess 160 is in broad contact with the side surface of the conductive member 400, resulting in increased heat transfer between the two.

[0051] If the conductive member 400 excessively cools or heats the dielectric substrate 100 locally, it may lead to large variations in the in-plane temperature distribution of the substrate W during processing. Therefore, in the electrostatic chuck 10 according to this embodiment, this in-plane temperature distribution problem is also solved by devising the shapes of the first recess 160 and the second recess 260.

[0052] In this embodiment, the diameter of the inner circumferential surface 261 of the second recess 260 is approximately equal to the diameter of the main body portion 410 of the conductive member 400. On the other hand, the diameter of the inner circumferential surface 161 of the first recess 160 is larger than the diameter of the inner circumferential surface 261 of the second recess 260. Therefore, in a top view, the first recess 160 is larger than the second recess 260. The inner circumferential surface 161 of the first recess 160 is located outside the inner circumferential surface 261 of the second recess 260 along its entire circumference.

[0053] This configuration ensures that a constant distance is maintained around the entire circumference from the inner surface 161 of the first recess 160 to the side surface of the conductive member 400. A relatively large gap is formed between the inner surface 161 of the first recess 160 and the side surface of the conductive member 400, reducing heat transfer between them. As a result, localized temperature increases and decreases are less likely to occur near the conductive member 400 on the dielectric substrate 100, thus suppressing variations in the in-plane temperature distribution of the substrate W during processing.

[0054] If the workability during joining described above is not an issue, the diameter of the inner circumferential surface 261 of the second recess 260 may be larger than the diameter of the main body 410 of the conductive member 400. In this case as well, the diameter of the inner circumferential surface 161 of the first recess 160 may be made even larger than the diameter of the inner circumferential surface 261 of the second recess 260.

[0055] In a top view, the inner circumferential surface 161 of the first recess 160 and the inner circumferential surface 261 of the second recess 260 may be in close proximity to each other in some areas, or overlapping in some areas. However, in order to sufficiently suppress heat transfer between the dielectric substrate 100 and the conductive member 400, it is preferable that, as in this embodiment, the inner circumferential surface 161 of the first recess 160 and the inner circumferential surface 261 of the second recess 260 are concentric in a top view.

[0056] The conductive member 400 may be configured such that the diameter of the portion of the conductive member 400 housed in the first recess 160 and the diameter of the portion of the conductive member 400 housed in the second recess 260 are different from each other. In this case as well, it is preferable to form the first recess 160 and the second recess 260 such that the distance from the inner circumferential surface 161 of the first recess 160 to the side surface of the conductive member 400 is greater than the distance from the inner circumferential surface 261 of the second recess 260 to the side surface of the conductive member 400, over the entire circumference.

[0057] The second embodiment will now be described. The following will primarily focus on the differences from the first embodiment, while common points will be omitted as appropriate.

[0058] Figure 5 shows the configuration of the electrostatic chuck 10 according to this embodiment, from the same viewpoint as in Figure 2. As shown in Figure 5, the first recess 160 in this embodiment is not formed to a depth that exposes the RF electrode 140. The bottom surface 162 of the first recess 160 is located on the surface 120 side of the RF electrode 140.

[0059] The bottom surface 162 of the first recess 160 is covered by a metal plate 141. The metal plate 141 is a plate-shaped member made of, for example, molybdenum, and is in close contact with substantially the entire bottom surface 162. In this embodiment, the tip of the projection 420 is pressed against the metal plate 141.

[0060] The metal plate 141 and the RF electrode 140 are electrically connected by a plurality of via portions 142 provided in the dielectric substrate 100. Each via portion 142 is formed by filling the inside of a hole that extends along a direction perpendicular to the surface 120 with a conductive material such as tungsten. One end of each via portion 142 is connected to the metal plate 141, and the other end is connected to the RF electrode 140.

[0061] Thus, in this embodiment, the conductive member 400 and the RF electrode 140 are not directly connected, but are indirectly connected via the metal plate 141 and the via portion 142. This configuration also provides the same effects as those described in the first embodiment.

[0062] A third embodiment will now be described. The following will primarily focus on the differences from the first embodiment, while commonalities will be omitted as appropriate.

[0063] Figure 6 shows the configuration of the electrostatic chuck 10 according to this embodiment, from the same viewpoint as in Figure 2. As shown in Figure 6, in this embodiment, the diameter of the inner circumferential surface 161 of the first recess 160 is approximately equal to the diameter of the main body portion 410 of the conductive member 400. On the other hand, the diameter of the inner circumferential surface 261 of the second recess 260 is larger than the diameter of the inner circumferential surface 161 of the first recess 160. Therefore, in a top view, the second recess 260 is larger than the first recess 160. The inner circumferential surface 261 of the second recess 260 is located outside the inner circumferential surface 161 of the first recess 160 along its entire circumference.

[0064] The shape of the conductive member 400 is the same as in the first embodiment. Therefore, in a top view, the diameter of the portion of the conductive member 400 housed in the first recess 160 is equal to the diameter of the portion of the conductive member 400 housed in the second recess 260.

[0065] In this embodiment, a method for manufacturing the electrostatic chuck 10, specifically a method for joining the dielectric substrate 100 and the base plate 200, will be described with reference to Figure 7. In Figure 7, the configurations of the dielectric substrate 100, the base plate 200, and the conductive member 400 are simplified and schematic.

[0066] First, the dielectric substrate 100 is placed on a workbench (not shown) with its surface 120 facing upwards. A first recess 160 is pre-formed on surface 120. In addition, an adhesive that will become a bonding layer 300 after curing is pre-applied to substantially the entire surface 120. In Figure 7, the illustration of the adhesive is omitted. The adhesive may also be pre-applied to surface 210 of the base plate 200.

[0067] Next, the conductive members 400 are inserted into each of the first recesses 160. As shown in Figure 7, each conductive member 400 protrudes vertically from the surface 120 of the dielectric substrate 100.

[0068] Next, the base plate 200 is brought closer to the surface 120 from above, with the surface 210 facing downwards. A second recess 260 is pre-formed on the surface 210. The dielectric substrate 100 and the base plate 200 are aligned with each other so that each second recess 260 is directly above each first recess 160. The base plate 200 is moved along the arrows in Figure 7 and bonded to the dielectric substrate 100. Once the movement is complete, each conductive member 400 is housed inside the first recess 160 and the second recess 260. The electrostatic chuck 10 according to this embodiment is then completed by heating the entire assembly to cure the adhesive.

[0069] If the inner diameter of the second recess 260 formed in the base plate 200 were smaller than the inner diameter in this embodiment, for example, if it were about the same as the inner diameter of the first recess 160, then aligning the base plate 200 when moving it closer to the dielectric substrate 100 on the lower side would become difficult. In other words, it would become difficult to get each conductive member 400 inside the second recess 260. Therefore, in this embodiment, the inner diameter of the second recess 260 is made larger than the inner diameter of the first recess 160. This makes it possible to easily get each conductive member 400 inside the second recess 260 while moving the dielectric substrate 100 downwards.

[0070] Furthermore, if the inner diameter of the first recess 160 formed in the dielectric substrate 100 is larger than the inner diameter in this embodiment, the gap between the inner circumferential surface 161 of the first recess 160 and the conductive member 400 will increase, making it difficult to achieve the state in which the conductive member 400 protrudes vertically from the surface 120 of the dielectric substrate 100. Also, since the position of the conductive member 400 in this state cannot be precisely determined, it becomes difficult to align the base plate 200 when bringing it closer to the dielectric substrate 100 on the lower side. Therefore, in this embodiment, the inner diameter of the first recess 160 is made smaller than the inner diameter of the second recess 260, and is about the same size as the outer diameter of the conductive member 400. Since a part of the conductive member 400 is inserted into the relatively small first recess 160, tilting and displacement of the conductive member 400 are prevented. As a result, the above-mentioned joining work during the manufacturing of the electrostatic chuck 10 can be easily performed.

[0071] Thus, even in a configuration where the relative sizes of the first recess 160 and the second recess 260 in a top view are reversed compared to the first embodiment, the same effects as those described in the first embodiment can be achieved. Whether the first recess 160 or the second recess 260 should be made larger can be determined by which member is placed on the lower side when joining the dielectric substrate 100 and the base plate 200.

[0072] A fourth embodiment will now be described. The following will primarily focus on the differences from the third embodiment described above, while common points will be omitted as appropriate.

[0073] Figure 8 shows the configuration of the electrostatic chuck 10 according to this embodiment, from the same viewpoint as in Figure 6. As shown in Figure 8, the first recess 160 in this embodiment is not formed to a depth that exposes the RF electrode 140. The bottom surface 162 of the first recess 160 is located on the surface 120 side of the RF electrode 140.

[0074] The bottom surface 162 of the first recess 160 is covered by a metal plate 141. The metal plate 141 is a plate-shaped member made of, for example, molybdenum, and is in close contact with substantially the entire bottom surface 162. In this embodiment, the tip of the projection 420 is pressed against the metal plate 141.

[0075] The metal plate 141 and the RF electrode 140 are electrically connected by a plurality of via portions 142 provided in the dielectric substrate 100. Each via portion 142 is formed by filling the inside of a hole that extends along a direction perpendicular to the surface 120 with a conductive material such as tungsten. One end of each via portion 142 is connected to the metal plate 141, and the other end is connected to the RF electrode 140.

[0076] Thus, in this embodiment, the conductive member 400 and the RF electrode 140 are not directly connected, but are indirectly connected via the metal plate 141 and the via portion 142. This configuration also provides the same effects as those described in the third embodiment.

[0077] The embodiments have been described above with reference to specific examples. However, this disclosure is not limited to these specific examples. Modifications made to these specific examples by those skilled in the art are also included within the scope of this disclosure, as long as they retain the features of this disclosure. The elements, their arrangement, conditions, shapes, etc., of each of the aforementioned specific examples are not limited to those illustrated and can be modified as appropriate. The elements of each of the aforementioned specific examples can be combined in different ways as appropriate, as long as no technical inconsistencies arise. [Explanation of symbols]

[0078] 10: Electrostatic Chuck 100: Dielectric substrate 110,120: face 140:RF electrode 160: First recess 400: Conductive material 200: Base plate 210: Face 260: Second recess W: Circuit board

Claims

1. A dielectric substrate having a mounting surface on which an object to be adsorbed is placed, An internal electrode provided inside the dielectric substrate, A base plate formed of metal and bonded to the dielectric substrate, The system includes a conductive member that electrically connects the internal electrode and the base plate, A first recess is formed on the surface of the dielectric substrate that is on the base plate side, for accommodating a part of the conductive member. A second recess is formed on the surface of the base plate facing the dielectric substrate, which accommodates a portion of the conductive member. An electrostatic chuck characterized in that, when viewed from a direction perpendicular to the mounting surface, one of the first recess and the second recess is larger than the other.

2. The electrostatic chuck according to claim 1, characterized in that, when viewed from a direction perpendicular to the mounting surface, the first recess is larger than the second recess.

3. When viewed from a direction perpendicular to the mounting surface, The electrostatic chuck according to claim 2, characterized in that the inner circumferential surface of the first recess is located outside the inner circumferential surface of the second recess over its entire circumference.

4. When viewed from a direction perpendicular to the mounting surface, The electrostatic chuck according to claim 3, characterized in that the diameter of the portion of the conductive member housed in the first recess is equal to the diameter of the portion of the conductive member housed in the second recess.

5. The electrostatic chuck according to claim 1, characterized in that, when viewed from a direction perpendicular to the mounting surface, the second recess is larger than the first recess.

6. When viewed from a direction perpendicular to the mounting surface, The electrostatic chuck according to claim 5, characterized in that the inner circumferential surface of the second recess is located outside the inner circumferential surface of the first recess over its entire circumference.

7. When viewed from a direction perpendicular to the mounting surface, The electrostatic chuck according to claim 6, characterized in that the diameter of the portion of the conductive member housed in the first recess is equal to the diameter of the portion of the conductive member housed in the second recess.

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