Electrostatic chuck and method for manufacturing the same

Abstract

To provide an electrostatic chuck capable of suppressing a manufacturing cost of a base plate and a method for manufacturing the same.SOLUTION: An electrostatic chuck 10 comprises a dielectric substrate 100 with a plurality of gas holes 140, a base plate 200 with gas holes 240, and a bonding layer 300 provided between the dielectric substrate 100 and the base plate 200 and formed of an insulating material. A plurality of openings 142 being the ends of gas holes 140, is formed in a surface 120 of the dielectric substrate 100 on a side of the bonding layer 300. An opening 241, the end of the gas hole 240, is formed in a surface 210 of the base plate 200 on the side of the bonding layer 300. The opening 241 is connected to the plurality of openings 142 via the connecting groove 150 formed on a surface 120 of the dielectric substrate 100 on a side of the bonding layer 300.SELECTED DRAWING: Figure 1

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, 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 as described in Patent Document 1 below, a 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] In order to adjust the temperature of the substrate during processing, an inert gas such as helium is often supplied between the dielectric substrate and the substrate. Gas holes are formed in the dielectric substrate and the base plate as supply paths for such gas. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2005-203426 A Summary of the Invention [Problem to be solved by the invention]

[0005] In order to suppress temperature unevenness of the substrate, it is preferable to supply gas as evenly as possible to each portion between the dielectric substrates. For this reason, the dielectric substrate is generally provided with a large number of gas holes so that the openings that serve as gas supply ports are distributed approximately evenly along the chucking surface.

[0006] Since the dielectric substrate has a large number of gas holes, it is not practical to connect the same number of pipes to the base plate from the outside as the gas holes. For this reason, in a conventional electrostatic chuck, a flow path through which helium gas supplied from the outside passes is branched into multiple paths inside the base plate, and each of the branched paths is guided to each gas hole in the dielectric substrate. In other words, the flow paths connected to each of the multiple gas holes provided in the dielectric substrate are consolidated into a small number of flow paths inside the base plate, and gas pipes from the outside are connected to the consolidated flow paths.

[0007] In order to form branched flow paths inside the base plate, it is necessary to take a method such as dividing the base plate into multiple parts, forming grooves in some parts, and then welding the other parts, etc. This makes the manufacturing process of the base plate complicated, resulting in high manufacturing costs.

[0008] With the advancement of semiconductor manufacturing technology, the performance required of electrostatic chucks is getting higher year by year, and the structure of electrostatic chucks is expected to become more complex in the future. For example, heaters, RF electrodes, etc. are often built into dielectric substrates, and it is necessary to run electric paths connected to these through the base plate. In addition, the configuration of the coolant flow path formed in the base plate is becoming more complex in order to make the in-plane temperature distribution of the substrate uniform during processing. Under these circumstances, it is expected that it will become even more difficult in the future to form a complex flow path for passing gas inside the base plate from the viewpoint of manufacturing costs, etc.

[0009] The present invention has been made in consideration of the above problems, and has an object to provide an electrostatic chuck that can reduce the manufacturing costs of a base plate, and a manufacturing method thereof. [Means for solving the problem]

[0010] In order to solve the above problems, the electrostatic chuck according to the present invention includes a dielectric substrate having a plurality of first gas holes formed therein, a base plate having a second gas hole formed therein, and a bonding layer formed of an insulating material and disposed between the dielectric substrate and the base plate. A plurality of first openings, which are ends of the first gas holes, are formed on the surface of the dielectric substrate facing the bonding layer. A second opening, which is an end of the second gas hole, is formed on the surface of the base plate facing the bonding layer. The second openings are connected to the plurality of first openings via communication grooves formed on the surface of the dielectric substrate facing the bonding layer.

[0011] In the electrostatic chuck having such a configuration, the second opening of the base plate is communicated with the first openings of the dielectric substrate via the communication grooves provided in the dielectric substrate, and since it is not necessary to form communication paths connecting the first gas holes and the second gas holes inside the base plate, the manufacturing cost of the base plate can be reduced.

[0012] In addition, in the above configuration, it is not necessary to provide the same number of second openings as the first openings in the base plate. Therefore, the number of second openings can be reduced compared to the conventional method. Although metal is exposed inside the second openings, by reducing the number of second openings that can be the starting point of discharge, there is an advantage that the possibility of discharge occurring is lower than in the conventional method.

[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, which makes it possible to further suppress the occurrence of discharge.

[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 cured solid adhesive sheet, which can reliably prevent uncured adhesive from entering the communicating grooves or blocking the communicating grooves during the process of curing the adhesive.

[0016] A method for manufacturing an electrostatic chuck according to the present invention includes the steps of: preparing a dielectric substrate having a first gas hole and a communicating groove connected to a first opening which is an end of the first gas hole; preparing a base plate having a second gas hole and a second opening which is an end of the second gas hole; preparing a solid adhesive sheet which is an insulating member; placing a surface of the dielectric substrate having the first opening which is an end of the first gas hole and a surface of the base plate having the second opening which is an end of the second gas hole facing each other so that the second opening and the multiple first openings are communicated by the communicating grooves, sandwiching the adhesive sheet between the dielectric substrate and the base plate; and curing the adhesive sheet.

[0017] According to this method for manufacturing an electrostatic chuck, it is possible to easily manufacture the electrostatic chuck having the above-described configuration in which the communicating groove is formed in the base plate. Effect of the Invention

[0018] According to the present invention, it is possible to provide an electrostatic chuck that can reduce the manufacturing cost of a base plate, and a manufacturing method thereof. [Brief description of the drawings]

[0019] [Figure 1] 1 is a cross-sectional view illustrating a schematic configuration of an electrostatic chuck according to an embodiment of the present invention. [Diagram 2] 2 is a diagram showing a configuration of a dielectric substrate provided in the electrostatic chuck of FIG. 1. [Diagram 3] 2 is a diagram showing a configuration of a base plate included in the electrostatic chuck shown in FIG. 1. [Figure 4]2 is a diagram showing a configuration of a bonding layer provided in the electrostatic chuck of FIG. 1. [Diagram 5] 2 is a diagram showing a configuration of a dielectric substrate provided in the electrostatic chuck of FIG. 1. [Figure 6] 2 is a diagram for explaining a gas flow via a communication groove in the electrostatic chuck of FIG. 1. FIG. [Figure 7] 2A to 2C are diagrams for explaining a method for manufacturing the electrostatic chuck of FIG. [Figure 8] 13A and 13B are diagrams for explaining a gas flow via a communication groove in an electrostatic chuck according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] 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.

[0021] The 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.

[0022] 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.

[0023] The dielectric substrate 100 is a substantially disk-shaped member made of a sintered ceramic body. The dielectric substrate 100 is made of, for example, high-purity aluminum oxide (Al 2 O 3 ), 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, etc. required for the dielectric substrate 100 in the semiconductor manufacturing equipment.

[0024] 1 of the dielectric substrate 100 is an "attraction surface" on which the substrate W is placed. Also, a lower surface 120 of the dielectric substrate 100 in FIG. 1 is a "bonded 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".

[0025] 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. 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, or only one may be provided as a so-called "monopolar" electrode.

[0026] In Fig. 1, the entire power supply line 13 is depicted in a simplified manner. The portion of the power supply line 13 inside the dielectric substrate 100 is configured as, for example, a long and narrow via (hole) filled with a conductor, and an electrode terminal 103 (not shown in Fig. 1, see Fig. 5) is provided at the lower end of the via. The portion of the power supply line 13 penetrating the base plate 200 is a rod-shaped metal (bus bar) having one end connected to the electrode terminal 103. The base plate 200 is formed with a through hole 213 (not shown in Fig. 1, see Fig. 3) for inserting the metal.

[0027] 1, a space SP is formed between the dielectric substrate 100 and the substrate W. When a film formation process is performed in the semiconductor manufacturing apparatus, helium gas for temperature adjustment is supplied to the space SP from the outside through a gas hole 140 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.

[0028] Fig. 2 is a top view of the dielectric substrate 100. As shown in Fig. 2, a seal ring 111 and dots 112 are provided on a surface 110 that is an adsorption surface, and the above-mentioned space SP is formed around these.

[0029] The seal rings 111 are walls that divide the space SP, and a plurality of seal rings 111 are provided so as to be arranged concentrically when viewed from above. The upper end of each seal ring 111 forms part of the surface 110 and abuts against the substrate W. In this embodiment, a total of four seal rings 111 are provided, thereby dividing the space SP into four. 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 closer to uniform.

[0030] 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.

[0031] The dots 112 are circular protrusions protruding from the bottom surface 116. As shown in Fig. 2, 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.

[0032] Groove 113 and opening 141 are formed in bottom surface 116 of each space SP. Groove 113 is formed so as to recede further from bottom surface 116 toward surface 120. Groove 113 is formed for the purpose of quickly diffusing helium gas supplied from opening 141, which will be described below, into space SP and making the pressure distribution in space SP approximately uniform within a short period of time.

[0033] The opening 141 is an opening provided as an outlet for helium gas supplied into the space SP. As shown in FIG. 1, the dielectric substrate 100 is formed with gas holes 140 that run vertically from the surface 110 to the surface 120. A plurality of gas holes 140 are formed in each space SP, and one end of each gas hole 140 becomes the above-mentioned opening 141. The other end of each gas hole 140 becomes an opening 142 formed in the surface 120 of the dielectric substrate 100. Each opening 141 may be formed as a single opening as in this embodiment, or may be formed as a collection of a plurality of small openings.

[0034] Gas hole 140 corresponds to the "first gas hole" in this embodiment. Of gas hole 140, opening 142 formed on surface 120 corresponds to the "first opening" in this embodiment. Gas hole 140 has an enlarged diameter at the portion on the surface 120 side. Therefore, the inner diameter of opening 142 is slightly larger than the inner diameter of gas hole 140 in the other portion.

[0035] As shown in Fig. 2, in this embodiment, all of the openings 141 are formed at positions that overlap with the grooves 113 in a top view. For convenience of illustration, the diameter of the openings 141 is depicted in Fig. 2 as being larger than the width of the grooves 113, but the actual diameter of the openings 141 is smaller than the width of the grooves 113 as shown in Fig. 1. The width of the grooves 113 may be locally larger at the positions of the openings 141 so that the openings 141 fit inside the grooves 113.

[0036] In Fig. 2, the reference numeral "115" denotes holes through which lift pins (not shown) provided in the semiconductor manufacturing equipment are inserted. The holes are also referred to as "lift pin holes 115" below. A total of three lift pin holes 115 are formed, and are disposed at equal intervals of 120 degrees. The substrate W is attached to and detached from the surface 110 of the dielectric substrate 100 by the lift pins that move up and down through the lift pin holes 115.

[0037] Returning to Fig. 1, the explanation will be continued. The base plate 200 is a substantially disk-shaped member that supports the dielectric substrate 100. The base plate 200 is formed of a metal such as aluminum. Of the base plate 200, a surface 210 on the upper side in Fig. 1 is a "bonded surface" that is bonded to the dielectric substrate 100 via a bonding layer 300.

[0038] 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. Therefore, on the surface 210, except for the portion where the opening 241 described later is formed, the metal constituting the base plate 200 is not exposed at all to the bonding layer 300 side. The range of the base plate 200 on which the insulating film 230 is formed may be a range different from the example of FIG. 1. For example, the insulating film 230 may be formed only on the surface 210, which is the surface to be bonded.

[0039] A coolant flow path 250 for flowing a coolant is formed inside the base plate 200. When a film formation process is performed in the semiconductor manufacturing apparatus, a coolant is supplied to the coolant flow path 250 from the outside, thereby cooling the base plate 200. Heat generated in the substrate W during the film formation 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.

[0040] 1, the base plate 200 is formed with gas holes 240 that extend vertically from the surface 210 toward the surface 220. The gas holes 240 may be formed so as to extend linearly as a whole as in this embodiment, but may also be formed so as to bend midway toward the surface 220.

[0041] A plurality of gas holes 240 are formed in the base plate 200. An end of each gas hole 240 on the surface 210 side is an opening 241 formed in the surface 210. An end of each gas hole 240 on the surface 220 side is an opening 242 formed in the surface 220. The gas holes 240 correspond to the "second gas hole" in this embodiment. Of the gas holes 240, the opening 241 formed in the surface 210 corresponds to the "second opening" in this embodiment.

[0042] The gas holes 240 are holes that communicate with the gas holes 140 described above, and are part of a path for supplying helium gas to the space SP. However, the gas holes 240 are provided at positions different from the gas holes 140 when viewed from above. Also, the number of the gas holes 240 is different from the number of the gas holes 140.

[0043] 3 is a top view of only surface 210 of base plate 200, similar to FIG. 2. As shown in FIG. 3, in this embodiment, a total of four gas holes 240 are formed, and four openings 241, which are the ends of each hole, are formed on surface 210. As is clear from comparing FIG. 2 with FIG. 3, the position at which opening 241 is formed in top view is different from the position at which opening 141 and opening 142 of dielectric substrate 100 are formed. As will be described later, gas holes 140 and gas holes 240 at different positions communicate with each other through communication groove 150 provided in dielectric substrate 100.

[0044] As shown in FIG. 3, the base plate 200 is formed with a through hole 213 and a lift pin hole 215 , the ends of which are open at the surface 210 .

[0045] As described above, the through holes 213 are holes for passing the power supply paths 13 through. Two through holes 213 are formed corresponding to the number of the attraction electrodes 130. The lift pin holes 215 are holes through which lift pins are inserted, similar to the lift pin holes 115. Three lift pin holes 215 are provided in total, and are formed at positions corresponding to the respective lift pin holes 115 when viewed from above.

[0046] Returning to Fig. 1, the explanation will be continued. The bonding layer 300 is a layer provided between the dielectric substrate 100 and the base plate 200, and bonds the two 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.

[0047] Fig. 4 is a top view of only the bonding layer 300 taken out from the electrostatic chuck 10, similar to Fig. 2 and Fig. 3. As shown in Fig. 4, a plurality of through holes are formed in the bonding layer 300. These through holes include an electrode hole 313, a lift pin hole 315, and a communication hole 340.

[0048] The electrode holes 313 are holes for passing the power supply paths 13, similar to the through holes 213. Two electrode holes 313 are provided in total, and are formed at positions corresponding to the through holes 213, respectively, when viewed from above.

[0049] The lift pin holes 315 are holes through which lift pins are inserted, similar to the lift pin holes 215. Three lift pin holes 315 are provided in total, and are formed at positions corresponding to the lift pin holes 215, respectively, when viewed from above.

[0050] The communication holes 340 are holes formed to allow the helium gas to pass through from the gas holes 240. A total of four communication holes 340 are provided, each formed at a position overlapping with an opening 241 in top view. The communication holes 340 are circular holes, and the inner diameter thereof is slightly larger than the inner diameter of the opening 241.

[0051] 5 is a diagram of dielectric substrate 100 viewed from surface 120. As shown in the figure, communication grooves 150 are formed in surface 120. Communication grooves 150 are provided to provide communication between gas holes 140 and gas holes 240 located at different positions. Each communication groove 150 includes an inlet portion 151 and connection portions 152 and 153.

[0052] The inlet portion 151 is a portion that serves as an inlet when helium gas that has passed through the gas hole 240 of the base plate 200 flows into the communication groove 150. The inlet portions 151 are formed in the same number as the openings 241 formed on the surface 210 of the base plate 200, and are provided at positions corresponding to the respective openings 241. That is, the inlet portion 151 is provided at each position that overlaps with the openings 241 in a top view. The inlet portion 151 is a substantially circular recess, and its inner diameter is slightly larger than the inner diameter of the opening 241. In the portion between the inlet portion 151 and the opening 241, the above-mentioned communication hole 340 is formed in the bonding layer 300.

[0053] The connecting portions 152 and 153 are grooves formed as flow paths connecting the inlet portion 151 and the openings 142. Of these, the connecting portion 153 is a groove extending in an arc shape along the circumferential direction so as to connect the multiple openings 142. The connecting portion 152 is a groove extending linearly from the inlet portion 151 toward the connecting portion 153 on the outer circumferential side thereof.

[0054] In this embodiment, a total of four communication grooves 150 are formed and are arranged in a line from the outer periphery side to the inner periphery side when viewed from above. Each communication groove 150 corresponds to each of the four divided spaces SP and is provided directly below each space SP.

[0055] 6 shows a schematic diagram of the flow of helium gas through the innermost communication groove 150. The arrows AR1 in the figure represent the flow of helium gas through the gas holes 240 of the base plate 200. After flowing into the communication groove 150 from the inlet portion 151, the helium gas flows through the connection portion 152 and into the connection portion 153 (arrow AR2). The helium gas then flows along the connection portion 153 (arrow AR3) and flows into each of the openings 142 of the dielectric substrate 100, and is supplied to the space SP through the gas holes 140 (arrow AR4). In the other communication grooves 150, helium gas also flows in the same manner as described above.

[0056] As described above, in the electrostatic chuck 10, the opening 241 (second opening) is communicated with the multiple openings 142 (first openings) via the communication groove 150 formed in the surface 120 of the dielectric substrate 100 on the bonding layer 300 side. The helium gas that has passed through the gas hole 240 flows from the opening 241 into the communication groove 150, and is then distributed from the communication groove 150 to each of the multiple openings 142 and is supplied to each portion of the space SP through the gas hole 140.

[0057] In such a configuration, while it is possible to provide a plurality of gas holes 140 in the dielectric substrate 100 and to supply helium gas evenly to each portion of the space SP, it is not necessary to provide the same number of gas holes 240 in the base plate 200. In other words, it is possible to supply helium gas evenly to each portion of the space SP via the communication grooves 150, while keeping the number of gas holes 240 provided in the base plate 200 to a minimum number (specifically, four, the same as the number of spaces SP).

[0058] Incidentally, as a configuration for distributing helium gas toward each gas hole 140, it is also possible to form a communication passage inside the base plate 200 instead of the communication groove 150 as in this embodiment. However, in order to form a communication passage of a complex shape inside the base plate 200, it becomes necessary to take a method such as dividing the base plate 200 into a plurality of parts, forming grooves in some parts, and then welding the other parts. This makes the manufacturing process of the base plate complicated, and increases the manufacturing cost.

[0059] In contrast to this, in the electrostatic chuck of the present embodiment, the communication grooves 150 are formed on the surface 120 of the dielectric substrate 100, not inside the base plate 200. Therefore, the manufacturing cost of the base plate 200 can be reduced, as compared to when the communication passages are formed inside the base plate 200.

[0060] Furthermore, when communication paths are formed inside the base plate 200, the same number of openings 241 as the openings 142 are formed on the surface 210 of the base plate 200. In contrast to this, in this embodiment, it is not necessary to provide the same number of openings 241 as the openings 142, so the number of openings 241 can be reduced compared to the conventional method. Although metal is exposed inside the openings 241, by reducing the number of openings 241 that can become the starting point of discharge, there is also an advantage that the possibility of discharge occurring is lower than in the conventional method.

[0061] The number of inlets 151 provided in one communication groove 150 may be two or more. In any case, it is preferable that the number of inlets 151 in each communication groove 150 is smaller than the number of openings 142.

[0062] As described above, the insulating film 230 is provided on the surface 210 of the base plate 200 on the bonding layer 300 side so as to cover the entire surface. In this configuration, the surface of the base plate 200 is covered by both the bonding layer 300 and the insulating film 230, so that the occurrence of discharge can be sufficiently suppressed. 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. Note that, if the insulating property can be sufficiently ensured by only the bonding layer 300, the insulating film 230 may not be formed on the base plate 200.

[0063] A brief description will be given of a method for manufacturing the electrostatic chuck 10. First, as shown in Fig. 7, 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] The dielectric substrate 100 is in a state where the chucking electrode 130, the gas hole 140, the opening 142, the seal ring 111, etc. are formed in advance before bonding. As a method for forming these, various well-known methods can be adopted. In addition, the dielectric substrate 100 is also formed in advance with the communication groove 150 of FIG. 5 before bonding, and the communication groove 150 is in a state where it is connected to the opening 142.

[0065] Before bonding, the base plate 200 is also in a state where the coolant flow passage 250, the gas hole 240, the opening 241, 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] As described above, the adhesive sheet 300A is in the form of a solid sheet even before curing. Therefore, for example, by performing a hole punching process using a mold, the communication holes 340, the electrode holes 313, the lift pin holes 315, etc. can be formed in advance before bonding.

[0068] After preparing the dielectric substrate 100, the base plate 200, and the adhesive sheet 300A as described above, the adhesive sheet 300A is sandwiched between the dielectric substrate 100 and the base plate 200 as shown in Fig. 7. Specifically, the surface 120 of the dielectric substrate 100 on which the openings 142 are formed and the surface 210 of the base plate 200 on which the openings 241 are formed are opposed to each other so that the openings 241 and the multiple openings 142 are communicated with each other by the communication grooves 150, and the adhesive sheet 300A is sandwiched between the dielectric substrate 100 and the base plate 200.

[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 such as the communication hole 340 formed in advance in the adhesive sheet 300A generally maintain their original shape even after the adhesive sheet 300A is cured. Therefore, no part of the adhesive sheet 300A enters the communication groove 150 formed in the dielectric substrate 100, and the communication groove 150 also maintains its original shape. 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 communication holes 340 and the like are formed in advance. By using the adhesive sheet 300A, the communication holes 340 and the like can be easily formed in the portion (adhesive sheet 300A) that will become the bonding layer 300 at a stage before bonding. In addition, it is possible to reliably prevent the communication groove 150 from being deformed or blocked during the process of curing the adhesive.

[0071] If the intrusion of the adhesive into the communication groove 150 can be prevented in some way, a liquid adhesive can be used instead of the adhesive sheet 300A as the adhesive for the bonding layer 300. For example, if a string-like solid material that acts as a "bank" for preventing the intrusion of the liquid adhesive is arranged in advance along the outer periphery of the communication groove 150, the communication hole 340, etc., and then bonding is performed, a bonding layer 300 similar to that of this embodiment can be formed.

[0072] The shape of the communicating groove 150 formed in the dielectric substrate 100 can be changed as appropriate. In Fig. 8, the communicating groove 150 of the electrostatic chuck 10 according to a modified example is illustrated in the same manner as in Fig. 6.

[0073] In this modification, an opening 241 of the base plate 200 is formed at a position overlapping one of the multiple openings 142 of the electrostatic chuck 10 in a top view.

[0074] For ease of explanation, in Fig. 8, the three openings 142 are labeled with the symbols "142A", "142B", and "142C", respectively. In the example of Fig. 8, gas hole 240 and opening 241 (not shown) are formed at a position directly below opening 142A. In other words, opening 142A is both an inlet for helium gas to flow into communicating groove 150 and an outlet for helium gas to flow out toward opening 142 located directly above it. Due to this configuration, communicating groove 150 of this modified example does not have inlet portion 151 and connecting portion 152.

[0075] A portion of the helium gas that has passed through gas hole 240 as indicated by arrow AR1 flows into opening 142A directly above it (arrow AR41) and is supplied to space SP through gas hole 140. Another portion of the helium gas that has passed through gas hole 240 as indicated by arrow AR1 flows from opening 142A along connecting portion 153 (arrow AR3) and flows from each of openings 142B and 142C into gas holes 140 in dielectric substrate 100 (arrow AR42) and is supplied to space SP through gas hole 140.

[0076] In this manner, the plurality of openings 142 through which helium gas is distributed and supplied from the opening 241 may be located in a position that partially overlaps with the opening 241 in a top view.

[0077] 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]

[0078] 10: Electrostatic chuck 100: Dielectric substrate 140: Gas hole 142:Aperture 150:Communication groove 200: Base plate 230: Insulating film 240: Gas hole 241:Aperture 300: Bonding layer

Claims

1. a dielectric substrate having a plurality of first gas holes formed therein; a base plate having a second gas hole formed therein; a bonding layer provided between the dielectric substrate and the base plate and made of an insulating material; a plurality of first openings, which are ends of the first gas holes, are formed on a surface of the dielectric substrate facing the bonding layer; a second opening, which is an end of the second gas hole, is formed in a surface of the base plate facing the bonding layer; The electrostatic chuck, characterized in that the second opening is connected to a plurality of the first openings via a communicating groove formed in a surface of the dielectric substrate facing the bonding layer.

2. 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.

3. 3. The electrostatic chuck according to claim 2, wherein the insulating film is a film formed by thermal spraying.

4. 2. The electrostatic chuck according to claim 1, wherein the bonding layer is a cured solid adhesive sheet.

5. preparing a dielectric substrate having a first gas hole and a communication groove connected to a first opening which is an end of the first gas hole; preparing a base plate having a second gas hole and a second opening that is an end of the second gas hole; A step of preparing a solid adhesive sheet that is an insulating member; a step of placing a surface of the dielectric substrate, on which a first opening that is an end of the first gas hole is formed, and a surface of the base plate, on which a second opening that is an end of the second gas hole is formed, facing each other so that the second opening and the plurality of first openings are communicated with each other by the communication groove, and sandwiching the adhesive sheet between the dielectric substrate and the base plate; and curing the adhesive sheet.

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