Electrostatic chuck and method for manufacturing the same

Abstract

To provide an electrostatic chuck, which can suppress variation of an in-plane temperature distribution of a substrate.SOLUTION: An electrostatic chuck 10 comprises a dielectric substrate 100 having a surface 110 on which a substrate W is placed and through holes (gas holes 150 and lift pin holes 160) formed through a surface 110, an electrode terminal 121 provided on a surface 120 of the dielectric substrate 100 opposite the surface 110, a base plate 200 bonded to the surface 120 of dielectric substrate 100, and a bonding layer 300 provided between the dielectric substrate 100 and the base plate 200 and formed of an insulating material. When viewed from a direction perpendicular to the surface 110, a space 340 is formed in the bonding layer 300 at a position that does not overlap either the through hole or the electrode terminal 121.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an electrostatic chuck and a method for manufacturing the same. [Background technology]

[0002] For example, in semiconductor manufacturing equipment such as a CVD device or an etching device, an electrostatic chuck is provided as a device for attracting and holding a substrate such as a silicon wafer to be processed. The electrostatic chuck includes a dielectric substrate provided with an attracting electrode and a base plate supporting the dielectric substrate, which are joined together. The attracting electrode is generally built into the dielectric substrate, but the metal base plate may also be used as the attracting electrode. When a voltage is applied to the attracting electrode, an electrostatic force is generated, and the substrate placed on the dielectric substrate is attracted and held.

[0003] During processing such as etching, it is necessary to maintain the temperature of the substrate at an appropriate temperature. For this reason, as described in Patent Document 1 below, a cooling gas is supplied between the substrate and the dielectric substrate, or a coolant is passed through a coolant flow path in the base plate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-165193 A Summary of the Invention [Problem to be solved by the invention]

[0005] During processing, in addition to maintaining the temperature of the substrate at an appropriate temperature as described above, it is also required to minimize the variation in temperature distribution (i.e., in-plane temperature distribution) in each part of the substrate. As a measure to make the in-plane temperature distribution of the substrate closer to uniform, measures such as providing multiple supply paths for cooling gas and controlling the pressure, etc. for each path, or providing multiple coolant flow paths and adjusting the coolant temperature for each path may be taken. However, there may be cases where such measures alone are not enough to sufficiently suppress the variation in the in-plane temperature distribution of the substrate.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrostatic chuck capable of suppressing variations in the in-plane temperature distribution of a substrate. [Means for solving the problem]

[0007] In order to solve the above problems, the electrostatic chuck according to the present invention includes a dielectric substrate having a mounting surface on which an object to be attracted is mounted and in which a through hole is formed through the mounting surface, an electrode terminal provided on a surface of the dielectric substrate opposite to the mounting surface, a base plate joined to the surface of the dielectric substrate opposite to the mounting surface, and a bonding layer provided between the dielectric substrate and the base plate and made of an insulating material, wherein a space is formed in a position of the bonding layer that does not overlap with either the through hole or the electrode terminal when viewed from a direction perpendicular to the mounting surface.

[0008] In an electrostatic chuck having such a configuration, the space in the bonding layer can function as a “thermal insulation layer.” For example, if a space is provided in the bonding layer at a position directly below a portion of the substrate that is likely to become cold, the temperature of the dielectric substrate and the substrate directly above that position can be increased, making it possible to make the in-plane temperature distribution of the substrate more uniform.

[0009] In the electrostatic chuck according to the present invention, when viewed from a direction perpendicular to the mounting surface, the spatial ratio, which is the ratio of the area of ​​the space per unit area of ​​the bonding layer, is defined as a spatial ratio, and it is also preferable that the spatial ratio in the center of the bonding layer is larger than the spatial ratio in the outer periphery of the bonding layer. By making the spatial ratio in the center larger, it is possible to increase the temperature in the center of the substrate, which tends to be low, and make the in-plane temperature distribution of the substrate closer to uniform.

[0010] In addition, in the electrostatic chuck according to the present invention, it is also preferable that a plurality of spaces are formed, and the density of the spaces in the center of the bonding layer is higher than the density of the spaces in the outer periphery of the bonding layer. By increasing the space ratio in the center by increasing the density of the spaces, it is possible to make the in-plane temperature distribution of the substrate closer to uniform. Note that the "density of the spaces" refers to the number of spaces arranged per unit area.

[0011] In addition, in the electrostatic chuck according to the present invention, it is also preferable that a plurality of spaces are formed, and each space arranged in the central part of the bonding layer is larger than each space arranged in the outer periphery of the bonding layer. By increasing the space ratio in the central part by adjusting the size of each space, it is possible to make the in-plane temperature distribution of the substrate closer to uniform.

[0012] In the electrostatic chuck according to the present invention, it is also preferable that the space is formed so as to penetrate the bonding layer in a direction perpendicular to the mounting surface. By ensuring the maximum thickness of the space functioning as a heat insulating layer, the effect of adjusting the temperature of the substrate can be improved.

[0013] In the electrostatic chuck according to the present invention, it is also preferable that an insulating film is provided on the surface of the base plate facing the bonding layer. In this configuration, the surface of the base plate is covered with both the bonding layer and the insulating film, making it possible to suppress the occurrence of discharge between the substrate and the base plate.

[0014] In the electrostatic chuck according to the present invention, it is also preferable that the insulating film is a film formed by thermal spraying. In such a configuration, a film having high insulating properties can be easily formed, and it becomes possible to suppress the occurrence of discharge.

[0015] In the electrostatic chuck according to the present invention, it is also preferable that the bonding layer is a solid adhesive sheet having a recess or a through hole formed therein in advance, the recess or through hole serving as the space can be easily formed in the adhesive sheet before bonding. Also, the space can be reliably prevented from being deformed or disappearing during the process of curing the adhesive.

[0016] In addition, in the electrostatic chuck of the present invention, a coolant flow path is formed in the base plate for flowing a coolant, and when viewed in a direction perpendicular to the mounting surface, it is preferable that the spatial ratio, which is the ratio of the spatial area per unit area of ​​the bonding layer, in a first portion of the bonding layer overlapping with the upstream side of the coolant flow path is larger than the spatial ratio in a second portion of the bonding layer overlapping with the downstream side of the coolant flow path.

[0017] In semiconductor manufacturing equipment, cleaning of the inside of the equipment may be performed after the processing of a substrate is completed. In the processing of the substrate, a low-temperature coolant is supplied to the base plate, but when cleaning is started, a coolant with a higher temperature is supplied to the base plate. Therefore, immediately after cleaning is started, the temperature of the base plate on the upstream side of the coolant flow path rises first, and the temperature of the base plate on the upstream side of the coolant flow path rises later. In this way, a temporary temperature difference occurs in the base plate at the start of cleaning. A similar temperature difference can occur in the dielectric substrate due to heat transfer from the base plate, but such a temperature difference is not desirable because ceramic sintered bodies are often used for dielectric substrates.

[0018] As a countermeasure, in the electrostatic chuck having the above configuration, the spatial ratio of the first portion of the bonding layer overlapping with the upstream side of the coolant flow path is made larger than the spatial ratio of the second portion of the bonding layer overlapping with the downstream side of the coolant flow path. The first portion suppresses the heat conduction from the portion of the base plate that becomes hotter first to the dielectric substrate, while the second portion relatively promotes the heat conduction from the portion that becomes hotter later to the dielectric substrate. This makes it possible to suppress the temperature difference in the dielectric substrate.

[0019] In the electrostatic chuck according to the present invention, it is also preferable that the first portion is located closer to the center than the second portion when viewed from a direction perpendicular to the mounting surface.

[0020] During processing of a substrate, the central portion of the substrate tends to be cooler than the peripheral portion. In the electrostatic chuck having the above configuration, by providing the first portion having a high spatial ratio at a position closer to the center, it is possible to increase the temperature of the central portion of the substrate during processing and make the in-plane temperature distribution closer to uniform.

[0021] A method for manufacturing an electrostatic chuck according to the present invention includes the steps of: preparing a dielectric substrate having a mounting surface on which an object to be attracted is placed, a through hole formed through the mounting surface, and an electrode terminal provided on a surface opposite the mounting surface; preparing a base plate; preparing a solid adhesive sheet which is an insulating member and has a space which is a recess or a through hole formed therein; bringing the surface of the dielectric substrate opposite the mounting surface and the base plate into opposition to each other, and sandwiching the adhesive sheet between the dielectric substrate and the base plate so that the space does not overlap with either the through hole or the electrode terminal; and hardening the adhesive sheet.

[0022] According to this method for manufacturing an electrostatic chuck, it is possible to easily manufacture an electrostatic chuck capable of suppressing the variation in the in-plane temperature distribution of the substrate as described above. Effect of the Invention

[0023] According to the present invention, it is possible to provide an electrostatic chuck capable of suppressing variations in the in-plane temperature distribution of a substrate. [Brief description of the drawings]

[0024] [Figure 1] 1 is a cross-sectional view illustrating a schematic configuration of an electrostatic chuck according to a first embodiment. [Diagram 2] 2 is a diagram showing a configuration of a bonding layer provided in the electrostatic chuck of FIG. 1. [Diagram 3] 2 is a diagram showing a configuration of a bonding layer provided in the electrostatic chuck of FIG. 1. [Figure 4] 13A and 13B are diagrams for explaining a configuration of a bonding layer in a modified example. [Diagram 5] 2A to 2C are diagrams for explaining a method for manufacturing the electrostatic chuck of FIG. [Figure 6] 11A and 11B are diagrams showing a configuration of a bonding layer included in the electrostatic chuck according to the second embodiment. [Figure 7] 13A to 13C are diagrams showing a configuration of a bonding layer included in an electrostatic chuck according to a third embodiment. [Figure 8] 13A to 13C are diagrams showing a configuration of a bonding layer included in an electrostatic chuck according to a fourth embodiment. [Figure 9] 13A to 13C are diagrams showing the configuration of a bonding layer and the like included in an electrostatic chuck according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components in each drawing are denoted by the same reference numerals as much as possible, and duplicated description will be omitted.

[0026] A first embodiment will be described. An electrostatic chuck 10 according to this embodiment is configured to electrostatically attract and hold a substrate W to be processed inside a semiconductor manufacturing apparatus (not shown), such as a CVD film forming apparatus. The substrate W is, for example, a silicon wafer. The electrostatic chuck 10 may be used in an apparatus other than a semiconductor manufacturing apparatus.

[0027] 1 shows, in a schematic cross-sectional view, the configuration of an electrostatic chuck 10 in a state in which the electrostatic chuck 10 attracts and holds a substrate W. The electrostatic chuck 10 includes a dielectric substrate 100, a base plate 200, and a bonding layer 300.

[0028] The dielectric substrate 100 is a substantially disk-shaped member made of a sintered ceramic body. The dielectric substrate 100 contains, for example, high-purity aluminum oxide (Al2O3), but may contain other materials. The purity, type, and additives of the ceramics in the dielectric substrate 100 can be appropriately set in consideration of the plasma resistance and other properties required for the dielectric substrate 100 in the semiconductor manufacturing equipment.

[0029] 1 of the dielectric substrate 100 is a "mounting surface" on which a substrate W, which is an object to be attracted, is placed. Also, a lower surface 120 of the dielectric substrate 100 in FIG. 1 is a "bonding surface" that is bonded to a base plate 200 via a bonding layer 300 described below. The viewpoint when the electrostatic chuck 10 is viewed from the side of the surface 110 along a direction perpendicular to the surface 110 is hereinafter also referred to as a "top view".

[0030] An adsorption electrode 130 is embedded inside the dielectric substrate 100. The adsorption electrode 130 is a thin, flat layer made of a metal material such as tungsten, and is disposed parallel to the surface 110. When a voltage is applied to the adsorption electrode 130 from the outside via the power supply path 13, an electrostatic force is generated between the surface 110 and the substrate W, thereby adsorbing and holding the substrate W. Two adsorption electrodes 130 may be provided as so-called "bipolar" electrodes as in this embodiment, or only one may be provided as a so-called "monopolar" electrode.

[0031] 1, the entire power feed path 13 is depicted in a simplified manner. The portion of the power feed path 13 inside the dielectric substrate 100 is configured, for example, as a long and narrow via (hole) filled with a conductor, and an electrode terminal 121 is provided at the lower end thereof. The electrode terminal 121 is embedded in the surface 120 opposite the surface 110 via an insulating member (not shown). The portion of the power feed path 13 penetrating the base plate 200 is a rod-shaped metal (bus bar) having one end connected to the electrode terminal 121. The base plate 200 is formed with a through hole 270 for inserting the metal therethrough.

[0032] A space SP is formed between the dielectric substrate 100 and the substrate W. When a process such as film formation is performed in the semiconductor manufacturing apparatus, helium gas for temperature adjustment is supplied from the outside to the space SP through a gas hole 150 described below. By providing helium gas between the dielectric substrate 100 and the substrate W, the thermal resistance between them is adjusted, and the temperature of the substrate W is thereby maintained at an appropriate temperature. The gas for temperature adjustment supplied to the space SP may be a type of gas other than helium.

[0033] A seal ring 111 and dots 112 are provided on a surface 110 which is an attraction surface, and a space SP is formed around these.

[0034] The seal ring 111 is a wall that divides the space SP at the outermost position. The upper end of each seal ring 111 forms part of the surface 110 and abuts against the substrate W. Note that a plurality of seal rings 111 may be provided to divide the space SP. With this configuration, it is possible to individually adjust the pressure of the helium gas in each space SP and make the surface temperature distribution of the substrate W during processing more uniform.

[0035] 1 and the like, the portion marked with the reference symbol "116" is the bottom surface of the space SP. Hereinafter, this portion will also be referred to as the "bottom surface 116." The seal ring 111, together with the dots 112 described below, is formed as a result of digging down a part of the surface 110 to the position of the bottom surface 116.

[0036] The dots 112 are circular protrusions protruding from the bottom surface 116. A plurality of dots 112 are provided and are distributed approximately evenly on the attraction surface of the dielectric substrate 100. The upper end of each dot 112 forms part of the surface 110 and abuts against the substrate W. By providing a plurality of such dots 112, bending of the substrate W is suppressed.

[0037] Grooves 113 are formed in bottom surface 116 of each space SP. Grooves 113 are formed so as to recede further from bottom surface 116 toward surface 120. Grooves 113 are formed for the purpose of quickly diffusing helium gas supplied from gas holes 150 into space SP and making the pressure distribution in space SP approximately uniform within a short period of time.

[0038] Gas holes 150 are formed in the dielectric substrate 100 so as to penetrate vertically from the surface 110 to the surface 120. A plurality of gas holes 150 are formed, but only one of them is shown in FIG. 1. The ends of the gas holes 150 on the space SP side are open at the bottom surface of the groove 113. The gas holes 150 correspond to "through holes" formed so as to penetrate the surface 110 of the dielectric substrate 100. At the portions of the chucking electrode 130 that intersect with the respective gas holes 150, openings 131 are formed to avoid interference with the gas holes 150. By forming such openings 131, the chucking electrode 130 is not exposed at the inner surface of the gas hole 150, so that discharge between the substrate W and the chucking electrode 130 is prevented.

[0039] The dielectric substrate 100 further has a lift pin hole 160 formed so as to penetrate vertically from the surface 110 toward the surface 120. The lift pin hole 160 is a hole through which a lift pin (not shown) provided in a semiconductor manufacturing device is inserted. A total of three lift pin holes 160 are formed and arranged so as to be equally spaced at 120 degrees, but only one of them is shown in FIG. 1. The substrate W is attached to and detached from the surface 110 of the dielectric substrate 100 by a lift pin that moves up and down through the lift pin hole 160. The lift pin hole 160 corresponds to a "through hole" formed so as to penetrate the surface 110 of the dielectric substrate 100, similar to the gas hole 150 described above. At the portions of the attraction electrode 130 that intersect with the respective lift pin holes 160, openings 132 are formed to avoid interference with the lift pin holes 160. By forming such an opening 132, the chucking electrode 130 is not exposed at the inner surface of the lift pin hole 160, so that discharge between the substrate W and the chucking electrode 130 is prevented.

[0040] The base plate 200 is a substantially disk-shaped member bonded to the surface 120 of the dielectric substrate 100 in order to support the dielectric substrate 100. The base plate 200 is formed of a metal such as aluminum. The surface 210 of the base plate 200 on the upper side in FIG. 1 is a "bonded surface" that is bonded to the dielectric substrate 100 via a bonding layer 300.

[0041] An insulating film 230 is formed on almost the entire surface of the base plate 200 except for the surface 220 on the lower side in Fig. 1. The insulating film 230 is a film made of an insulating material such as alumina, and is formed by, for example, thermal spraying. The surface 210 described above is entirely on the insulating film 230.

[0042] In such a configuration, the surface of the base plate 200 is covered with both the bonding layer 300 and the insulating film 230 described below, making it possible to suppress the occurrence of discharge between the substrate W and the base plate 200. As the insulating film 230, an alumina film formed by thermal spraying as in this embodiment is preferable, but it may be a film formed by another manufacturing method or made of another material.

[0043] The range of the base plate 200 on which the insulating film 230 is formed may be a range different from that shown in Fig. 1. For example, the insulating film 230 may be formed only on the surface 210, which is the surface to be joined. When discharge can be sufficiently prevented by the joining layer 300 alone, the insulating film 230 may not be necessary.

[0044] A coolant flow path 280 for flowing a coolant is formed inside the base plate 200. When a process such as film formation is performed in the semiconductor manufacturing apparatus, a coolant is supplied to the coolant flow path 280 from the outside, thereby cooling the base plate 200. Heat generated in the substrate W during the process is transferred to the coolant 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 coolant.

[0045] Gas holes 250 are formed in the base plate 200, extending vertically from the surface 210 toward the surface 220. The gas holes 250 are formed at positions overlapping with the gas holes 150 of the dielectric substrate 100 in a top view, and communicate with the gas holes 150 via through holes 310 provided in the bonding layer 300. The gas holes 250, together with the gas holes 150 of the dielectric substrate 100, form part of a path for supplying helium gas toward the space SP.

[0046] The gas holes 250 may be formed so as to extend linearly as in this embodiment, but may be formed so as to bend on the way to the surface 220. Also, the gas holes 250 on the surface 210 side may be aggregated into a small number of flow paths inside the base plate 200, and the flow paths may be configured to extend to the surface 220 side.

[0047] The base plate 200 is further formed with lift pin holes 260 that penetrate vertically from the surface 210 toward the surface 220. The lift pin holes 260 are holes through which lift pins (not shown) provided in a semiconductor manufacturing apparatus are inserted, similar to the lift pin holes 160 of the dielectric substrate 100. The lift pin holes 260 are formed at positions that overlap with the lift pin holes 160 of the dielectric substrate 100 in a top view, and are connected to the lift pin holes 160 via through holes 320 provided in the bonding layer 300.

[0048] The bonding layer 300 is a layer provided between the dielectric substrate 100 and the base plate 200, and bonds them together. The bonding layer 300 is formed by curing an adhesive made of an insulating material. For example, a polyimide-based adhesive can be used as such an adhesive.

[0049] 2 is a top view of the bonding layer 300. As shown in the figure, a plurality of through holes are formed in the bonding layer 300. These through holes include through holes 310, 320, 330, and 340.

[0050] As described above, through hole 310 is a hole formed to allow communication between gas hole 150 and gas hole 250. As described above, through hole 320 is a hole formed to allow communication between lift pin hole 160 and lift pin hole 260.

[0051] The through holes 330 are formed at positions overlapping with the electrode terminals 121 and the through holes 270 in top view. As shown in Fig. 1, the through holes 330 are holes formed to allow the power supply path 13 to pass therethrough.

[0052] In addition to the chucking electrode 130, other electrodes such as an RF electrode may be embedded in the dielectric substrate 100. In this case, electrode terminals connected to the electrodes are provided on the surface 120 of the dielectric substrate 100. Further, at positions of the bonding layer 300 overlapping with the electrode terminals in a top view, further through holes are formed for passing power supply paths connected to the electrode terminals.

[0053] The through holes 340 are holes formed at positions that do not overlap any of the through holes 310, 320, and 330 described above, and the electrode terminals 121. In other words, the through holes 340 are formed at positions that do not overlap any of the through holes (gas holes 150 and lift pin holes 160) formed in the dielectric substrate 100, and the electrode terminals 121, when viewed from above. A space formed inside each of the through holes 340 functions as a "thermal insulation layer" that prevents heat transfer between the dielectric substrate 100 and the base plate 200. The space formed inside the through holes 340 is hereinafter also referred to as "space 340."

[0054] In the electrostatic chuck 10 according to this embodiment, a plurality of spaces 340, which are heat insulating layers, are arranged in the bonding layer 300 so that the in-plane temperature distribution of the substrate W during processing becomes uniform. For example, if the space 340 is arranged in the bonding layer 300 at a position directly below a portion of the substrate W that is likely to become low temperature, the cooling by the base plate 200 is suppressed directly above that position, and the temperatures of the dielectric substrate 100 and the substrate W increase locally. This makes it possible to make the in-plane temperature distribution of the substrate W closer to uniform.

[0055] A specific arrangement of the space 340 will be described below. In order to make the arrangement of the space 340 clearer, in Fig. 3, the through holes 310, 320, and 330 in Fig. 2 are omitted, and only the space 340 is shown.

[0056] In this embodiment, a plurality of spaces 340 are formed in the bonding layer 300, and each of the spaces 340 is a circular space when viewed from above. Moreover, each of the spaces 340 has the same shape.

[0057] Here, the "space ratio" is defined as the ratio of the area of ​​the spaces 340 to the unit area of ​​the bonding layer 300 when viewed from a direction perpendicular to the surface 110 that is the mounting surface. The size of the "unit area" is not particularly limited, but an area that can include multiple or more of the largest spaces 340, such as the area surrounded by the dotted line DL1 in FIG. 3, may be set as the above-mentioned "unit area."

[0058] As shown in FIG. 3, in this embodiment, the spaces 340 are not evenly arranged in the entire bonding layer 300. Specifically, the spaces 340 are arranged so that the spatial ratio in the center of the bonding layer 300 is larger than the spatial ratio in the outer periphery of the bonding layer 300. The "center of the bonding layer 300" refers to, for example, the region surrounded by the dotted line DL1 in FIG. 3, and the "outer periphery of the bonding layer 300" refers to, for example, the region surrounded by the dotted line DL2 in FIG. 3. The areas surrounded by the dotted lines DL1 and DL2 are the same. The spatial ratio can also be expressed as the ratio of the total area of ​​the spaces 340 included in each dotted line region to the region.

[0059] In order to perform processes such as film formation and etching uniformly over the entire substrate W, it is desirable to make the in-plane temperature distribution of the substrate W as uniform as possible during the process. However, the outer periphery of the substrate W is less easily cooled by the electrostatic chuck 10 than the central portion of the substrate W, and tends to be hotter than the central portion. In other words, during the process of the substrate W, the central portion of the substrate W tends to be colder than the outer periphery.

[0060] Therefore, in the electrostatic chuck 10 according to this embodiment, the spatial ratio in the central portion of the bonding layer 300 is made larger than the spatial ratio in the outer periphery of the bonding layer 300. The central portion of the substrate W, which is likely to become cold, is less likely to be cooled from the base plate 200 due to the arrangement of the space 340, and the temperature of the central portion rises and approaches the temperature of the outer periphery. This makes it possible to make the in-plane temperature distribution of the substrate W more uniform.

[0061] In this embodiment, the multiple spaces 340 are formed to have the same shape, and are arranged such that the density of the spaces 340 in the center of the bonding layer 300 is higher than the density of the spaces 340 in the outer periphery of the bonding layer 300. By increasing the density of the spaces 340 to increase the spatial ratio in the center of the bonding layer 300, the in-plane temperature distribution of the substrate W can be made closer to uniform. Note that the "density of the spaces 340" refers to the number of spaces 340 arranged per unit area.

[0062] As shown in FIG. 1 and FIG. 4(A), each space 340 is formed as a "through hole" penetrating the bonding layer 300 along a direction perpendicular to the surface 110, which is the mounting surface. Instead of this embodiment, each space 340 may be formed as an internal space of a "bottomed hole" having a bottom 341 on the base plate 200 side, as in the modified example shown in FIG. 4(B). In other words, the space 340 may be formed as an internal space of a "recess" rather than a "through hole". However, from the viewpoint of maximizing the thickness of the space 340 functioning as a heat insulating layer and further enhancing the effect of temperature adjustment on the substrate W, it is preferable to form the space 340 as an internal space of a through hole, as in this embodiment.

[0063] A brief description will be given of a method for manufacturing the electrostatic chuck 10. First, as shown in Fig. 5, the dielectric substrate 100, the base plate 200, and the adhesive sheet 300A are prepared. Then, the dielectric substrate 100 and the base plate 200 are bonded together using the adhesive sheet 300A.

[0064] Before bonding, the dielectric substrate 100 is in a state in which gas holes 150 and lift pin holes 160 penetrating the surface 110, the chucking electrode 130, the electrode terminals 121, and the like are formed in advance. As a method for forming these, various known methods can be adopted.

[0065] Similarly, before bonding, the base plate 200 is also in a state in which the gas holes 250, the lift pin holes 260, the coolant flow paths 280, the insulating film 230, etc. are formed in advance. As a method for forming these, various known methods can be adopted.

[0066] The adhesive sheet 300A is an insulating member that hardens during bonding to become the bonding layer 300. In other words, the adhesive sheet 300A is an "adhesive", but is not liquid even before hardening, and is a flexible solid sheet-like member. For example, polyimide-, epoxy-, silicone-, acrylic-, or other adhesive films can be used as the adhesive sheet 300A. As the adhesive film, one with excellent thermal conductivity or high insulation can be preferably used.

[0067] Since the adhesive sheet 300A is in the form of a solid sheet even before curing as described above, it is possible to form through holes 310, 320, 330, 340, etc. in advance before bonding, for example, by performing a hole punching process using a mold. The through hole 340 is a hole that is formed in advance in the adhesive sheet 300A so as to eventually become the space 340, and corresponds to the "space portion" in this embodiment.

[0068] After preparing the dielectric substrate 100, the base plate 200, and the adhesive sheet 300A provided with the through holes 340 and the like as described above, the adhesive sheet 300A is sandwiched between the dielectric substrate 100 and the base plate 200 as shown in Fig. 5. Specifically, the surface 120 of the dielectric substrate 100 and the surface 210 of the base plate 200 are opposed to each other, and the adhesive sheet 300A is sandwiched between the dielectric substrate 100 and the base plate 200 so that the through holes 340 do not overlap any of the gas holes 150, the lift pin holes 160, and the electrode terminals 121.

[0069] With the adhesive sheet 300A sandwiched as described above, the dielectric substrate 100, the base plate 200, and the adhesive sheet 300A are heated to a predetermined temperature. By heating, the adhesive sheet 300A is cured while being bonded to both the surface 120 and the surface 210, and becomes the bonding layer 300 of FIG. 1. The through holes 340 and the like that were formed in advance in the adhesive sheet 300A generally maintain their original shapes even after the adhesive sheet 300A is cured. By the above-mentioned method, the electrostatic chuck 10 having the configuration shown in FIG. 1 is completed.

[0070] As described above, the bonding layer 300 of this embodiment is formed by curing the solid adhesive sheet 300A in which the through holes 340 are formed beforehand. By using the adhesive sheet 300A, the through holes 340 of a predetermined shape can be easily formed in the portion (adhesive sheet 300A) that will become the bonding layer 300 before bonding. In addition, it is possible to reliably prevent the spaces 340 from being deformed or disappearing during the process of curing the adhesive.

[0071] If deformation of the space 340 etc. during hardening can be prevented by some method, a liquid adhesive can be used instead of the adhesive sheet 300A as the adhesive that becomes the bonding layer 300. For example, if a string-like solid material that acts as a "bank" that prevents the intrusion of the liquid adhesive is arranged in advance along the periphery of the area that becomes the space 340 etc., and then bonding is performed, a bonding layer 300 similar to that of this embodiment can be formed.

[0072] 4(B), when each space 340 is formed as an internal space of a "bottomed hole" having a bottom 341 on the side of the base plate 200, a bottomed hole (i.e., a recess) instead of a through hole may be formed in advance at the corresponding position of the adhesive sheet 300A. In this case, the recess formed in the adhesive sheet 300A corresponds to the "space" that will eventually become the space 340.

[0073] A second embodiment will be described below. In the following, differences from the first embodiment will be mainly described, and descriptions of commonalities with the first embodiment will be omitted as appropriate.

[0074] This embodiment differs from the first embodiment in the arrangement of spaces 340 formed in the bonding layer 300. In Fig. 6, the configuration of the bonding layer 300 in this embodiment is illustrated in a similar manner to Fig. 3 .

[0075] In this embodiment, similarly to the first embodiment, a plurality of spaces 340 are formed in the bonding layer 300, and each of the spaces 340 is a circular space when viewed from above. Moreover, each of the spaces 340 has the same shape.

[0076] 6, in this embodiment, the spaces 340 are arranged such that the density of the spaces 340 gradually decreases (not stepwise) from the center of the bonding layer 300 toward the outer periphery. Therefore, the "space ratio" described above gradually decreases from the center of the bonding layer 300 toward the outer periphery. Even in this embodiment, the space ratio in the central portion of the bonding layer 300 (e.g., the region surrounded by the dotted line DL1) is larger than the space ratio in the outer periphery of the bonding layer 300 (e.g., the region surrounded by the dotted line DL2), so that the same effect as that described in the first embodiment is achieved.

[0077] A third embodiment will be described below. In the following, differences from the first embodiment will be mainly described, and descriptions of commonalities with the first embodiment will be omitted as appropriate.

[0078] This embodiment also differs from the first embodiment in the arrangement of spaces 340 formed in the bonding layer 300. In Fig. 7, the configuration of the bonding layer 300 in this embodiment is illustrated in a schematic manner similar to that in Fig. 3 .

[0079] In this embodiment, similarly to the first embodiment, a plurality of spaces 340 are formed in the bonding layer 300, and each space 340 is a circular space when viewed from above. However, the shapes of the spaces 340 are not all the same. The spaces 340 in this embodiment include a space 340A having a relatively large diameter and a space 340B having a relatively small diameter.

[0080] The space 340A is disposed in a region close to the center of the bonding layer 300, and the space 340B is disposed in an outer region thereof. That is, each space 340A disposed in the center of the bonding layer 300 is larger than each space 340B disposed in the outer periphery of the bonding layer 300. As a result, the spatial ratio in the center of the bonding layer 300 (e.g., the region surrounded by the dotted line DL1) is larger than the spatial ratio in the outer periphery (e.g., the region surrounded by the dotted line DL2). In this way, even in a configuration in which the spatial ratio in the center is increased by adjusting the size of each space 340, the same effect as that described in the first embodiment can be achieved.

[0081] Alternatively, the space 340 may be gradually (not stepwise) enlarged from the center of the bonding layer 300 toward the outer periphery.

[0082] A fourth embodiment will be described below. In the following, differences from the first embodiment will be mainly described, and descriptions of commonalities with the first embodiment will be omitted as appropriate.

[0083] This embodiment also differs from the first embodiment in the arrangement of the spaces 340 formed in the bonding layer 300. In FIG. 8, the configuration of the bonding layer 300 in this embodiment is illustrated in a similar manner to FIG. 3. As shown in the figure, only one space 340 in this embodiment is formed in the bonding layer 300, and is formed to extend in a spiral shape from the center of the bonding layer 300. The width dimension of the space 340 is uniform throughout. The interval between adjacent portions in the radial direction of the spirally extending space 340 gradually increases from the center of the bonding layer 300 toward the outer periphery. For example, the dimension L2 shown in FIG. 8 is larger than the inner dimension L1.

[0084] As a result, the spatial ratio in the central portion (e.g., the region surrounded by the dotted line DL1) of the bonding layer 300 is larger than the spatial ratio in the outer peripheral portion (e.g., the region surrounded by the dotted line DL2). Even with this configuration, the same effects as those described in the first embodiment can be achieved.

[0085] A fifth embodiment will be described below. In the following, differences from the first embodiment will be mainly described, and descriptions of commonalities with the first embodiment will be omitted as appropriate.

[0086] 9(A) is a schematic diagram of the configuration of the bonding layer 300 in this embodiment, in the same manner as in FIG. 3. In this embodiment, as in the first embodiment, a plurality of spaces 340 are formed in the bonding layer 300, and each space 340 is a circular space when viewed from above. The shapes of the spaces 340 are all the same. However, in this embodiment, the spaces 340 are only disposed in the center of the bonding layer 300, specifically, inside the region indicated by the dotted line DL11, and are not disposed outside the region.

[0087] Fig. 9(B) shows a schematic top view of the shape of the coolant flow path 280 formed in the base plate 200 of this embodiment. Although Fig. 9(B) shows only the inner portion of the surface 210 of the base plate 200, the coolant flow path 280 may extend to the outer region of the surface 210 in the top view. The dotted line DL12 in Fig. 9(B) represents the portion overlapping with the dotted line DL11 in the top view.

[0088] 9(B), the base plate 200 is provided with an inlet portion 281 and an outlet portion 282. The inlet portion 281 is an inlet for a coolant supplied to the base plate 200 from the outside, and the outlet portion 282 is an outlet for the coolant that has passed through the coolant flow path 280. Both of these are holes formed in the surface 220 of the base plate 200, and are connected to the flow path FP.

[0089] The refrigerant flow path 280 of this embodiment is a single flow path formed to extend in a spiral shape. An inlet portion 281 provided at one end of the refrigerant flow path 280 is provided at a position that is at or near the center of the surface 210 in top view, and is inside the area surrounded by the dotted line DL12. An outlet portion 282 provided at the other end of the refrigerant flow path 280 is provided at a position that is near the outer circumferential edge of the surface 210 in top view, and is outside the area surrounded by the dotted line DL12.

[0090] 9(A), the part of the bonding layer 300 inside the dotted line DL11 is also referred to as the "first part P1" below. The part of the bonding layer 300 outside the dotted line DL11 is also referred to as the "second part P2" below. The space 340 described above is disposed only in the first part P1, and is not disposed in the second part P2.

[0091] The first portion P1 of the bonding layer 300 overlaps with a portion of the coolant flow path 280 inside the dotted line DL12 in top view. In other words, the first portion P1 overlaps with the upstream side of the coolant flow path 280 in top view.

[0092] Further, the second portion P2 of the bonding layer 300 overlaps with a portion of the coolant flow path 280 outside the dotted line DL12 in top view. In other words, the second portion P2 overlaps with the downstream side of the coolant flow path 280 in top view.

[0093] With the above-described configuration, in this embodiment, the spatial ratio in the first portion P1 of the bonding layer 300 that overlaps with the upstream side of the refrigerant flow path 280 is greater than the spatial ratio in the second portion P2 of the bonding layer 300 that overlaps with the downstream side of the refrigerant flow path 280.

[0094] In a semiconductor manufacturing apparatus such as an etching apparatus, cleaning of the inside of the apparatus may be performed after the processing of the substrate W is completed. In the processing of the substrate W, a low-temperature coolant is supplied to the base plate 200 from the inlet portion 281, but when cleaning is started, a coolant with a higher temperature than before is supplied to the base plate 200 from the inlet portion 281. Therefore, immediately after cleaning is started, the temperature of the base plate 200 on the upstream side of the coolant flow path 280 rises first, and the temperature of the base plate 200 on the downstream side of the coolant flow path 280 rises later. In this way, a temporary temperature difference occurs in the base plate 200 at the start of cleaning. A similar temperature difference may occur in the dielectric substrate 100 due to heat transfer from the base plate 200, but such a temperature difference is not preferable because a ceramic sintered body is often used for the dielectric substrate 100 as in this embodiment.

[0095] As a countermeasure, in the electrostatic chuck 10 according to the present embodiment, as described above, the spatial ratio of the first portion P1 of the bonding layer 300 overlapping with the upstream side of the coolant flow passage 288 is made larger than the spatial ratio of the second portion P2 of the bonding layer 300 overlapping with the downstream side of the coolant flow passage 280. The first portion P1 suppresses the heat conduction from the portion of the base plate 200 that becomes hotter first (i.e., the portion inside the dotted line DL12) to the dielectric substrate 100, while the second portion P2 relatively promotes the heat conduction from the portion of the base plate 200 that becomes hotter later (i.e., the portion outside the dotted line DL12) to the dielectric substrate 100. This makes it possible to suppress the temperature difference in the dielectric substrate 100.

[0096] Furthermore, when the inlet portion 281 and the outlet portion 282 are interchanged, that is, when the refrigerant is supplied from the outer periphery of the base plate 200 and discharged from the center, the space 340 may be arranged, for example, only outside the dotted line DL11.

[0097] However, during processing of the substrate W, the central portion tends to be cooler than the peripheral portion of the substrate W. For this reason, it is preferable to provide the inlet portion 281 in the central portion as in this embodiment, and to provide the first portion P1 having a high spatial ratio at a position closer to the center than the second portion P2 having a low spatial ratio. With this configuration, as in the other embodiments, it is possible to increase the temperature of the central portion of the substrate W during processing and make the in-plane temperature distribution closer to uniform.

[0098] The arrangement of the spaces 340 in the bonding layer 300 may be different from the example shown in Fig. 9(A) For example, the spaces 340 may be arranged as in any of the examples shown in Figs.

[0099] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Any design modifications made by a person skilled in the art to these specific examples are also included within the scope of the present disclosure as long as they have the features of the present disclosure. The elements of each of the above-mentioned specific examples and their arrangements, conditions, shapes, etc. are not limited to those exemplified and can be changed as appropriate. The combination of each of the elements of each of the above-mentioned specific examples can be changed as appropriate as long as no technical contradiction occurs. [Explanation of symbols]

[0100] 10: Electrostatic chuck 100: Dielectric substrate 110,120: face 121: Electrode terminal 150: Gas hole 160: Lift pin hole 200: Base plate 300: Bonding layer 340: Space W: Substrate

Claims

1. a dielectric substrate having a mounting surface on which an object to be attached is placed and having a through hole penetrating the mounting surface; an electrode terminal provided on a surface of the dielectric substrate opposite to the mounting surface; a base plate joined to a surface of the dielectric substrate opposite to the mounting surface; a bonding layer provided between the dielectric substrate and the base plate and made of an insulating material; When viewed from a direction perpendicular to the placement surface, a space is formed in the bonding layer at a position that does not overlap either the through hole or the electrode terminal,

2. When viewed from a direction perpendicular to the placement surface, When the ratio of the area of ​​the space to the unit area of ​​the bonding layer is defined as the spatial ratio, 2. The electrostatic chuck of claim 1, wherein the space ratio at the center of the bonding layer is greater than the space ratio at the outer periphery of the bonding layer.

3. A plurality of the spaces are formed, 3. The electrostatic chuck according to claim 2, wherein a density of the spaces in a central portion of the bonding layer is higher than a density of the spaces in an outer periphery of the bonding layer.

4. A plurality of the spaces are formed, 3. The electrostatic chuck according to claim 2, wherein each of the spaces disposed in the central portion of the bonding layer is larger than each of the spaces disposed in the outer periphery of the bonding layer.

5. 2. The electrostatic chuck according to claim 1, wherein the space is formed so as to penetrate the bonding layer in a direction perpendicular to the mounting surface.

6. 2. The electrostatic chuck according to claim 1, wherein an insulating film is provided on a surface of the base plate that faces the bonding layer.

7. 7. The electrostatic chuck according to claim 6, wherein the insulating film is a film formed by thermal spraying.

8. 2. The electrostatic chuck according to claim 1, wherein the bonding layer is a cured solid adhesive sheet having a space, which is a recess or a through hole, formed in advance.

9. A coolant flow path for allowing a coolant to flow is formed in the base plate, When viewed from a direction perpendicular to the placement surface, When the ratio of the area of ​​the space to the unit area of ​​the bonding layer is defined as the spatial ratio, 2. The electrostatic chuck of claim 1, wherein the spatial ratio in a first portion of the bonding layer overlapping with an upstream side of the coolant flow path is greater than the spatial ratio in a second portion of the bonding layer overlapping with a downstream side of the coolant flow path.

10. When viewed from a direction perpendicular to the placement surface, 10. The electrostatic chuck of claim 9, wherein the first portion is located closer to the center than the second portion.

11. preparing a dielectric substrate having a mounting surface on which an object to be attracted is placed, a through hole penetrating the mounting surface, and an electrode terminal provided on a surface opposite to the mounting surface; Providing a base plate; A step of preparing a solid adhesive sheet that is an insulating member and has a space formed therein, which is a recess or a through hole; a step of placing a surface of the dielectric substrate opposite the mounting surface and the base plate so as to face each other, and sandwiching the adhesive sheet between the dielectric substrate and the base plate such that the space does not overlap with either the through hole or the electrode terminal; and curing the adhesive sheet.

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