Electrostatic chuck

Abstract

To provide an electrostatic chuck capable of preventing a support plate from deforming although a structure connected between a heater layer and a bypass layer by welding.SOLUTION: An electrostatic chuck 10 includes a dielectric substrate 100 and a heater unit 300 for heating the dielectric substrate 100. The heater unit 300 includes: a sub heater layer 330 for receiving the supply of electric power to generate heat; a bypass layer 370 having a part welded to the sub heater layer 330; and a pair of support plates 310 sandwiching the sub heater layer 330 and the bypass layer 370 therebetween. When using a part made by welding the sub heater layer 330 and the bypass layers 370 as a weld part 301, at least one of the pair of support plates 310 has an opening 311 at a position facing the weld 301.SELECTED DRAWING: Figure 8

Description

[Technical field]

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

[0002] For example, in semiconductor manufacturing equipment such as 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 has a dielectric substrate on which an attracting electrode is provided. 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] When a substrate is processed in a semiconductor manufacturing device, it is necessary to adjust the temperature so that the temperature distribution in the surface of the substrate is as uniform as possible. In order to enable highly accurate temperature adjustment, electrostatic chucks equipped with heaters have been developed in recent years and are already in practical use. The following Patent Document 1 describes an electrostatic chuck having a heater disposed between a dielectric substrate and a base plate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-197485 Summary of the Invention [Problem to be solved by the invention]

[0005] The present inventors have been studying how to unitize a heater used in an electrostatic chuck. For example, if a heater layer, which is a part that receives power and generates heat, is unitized by sandwiching it between a pair of support plates, it becomes possible to relatively easily attach it to an electrostatic chuck. When unitizing a heater, it is preferable to provide a bypass layer between the pair of support plates in addition to the heater layer. The bypass layer is a layer for electrically connecting between a power supply part that receives power from an outside and the heater layer. By providing the bypass layer, it becomes possible to increase the degree of freedom in arranging the power supply part in the heater unit.

[0006] It is preferable to connect the heater layer and the bypass layer by welding. However, when the two are connected by welding, the welded portion is likely to be locally raised. Therefore, when the entire heater layer and bypass layer including the welded portion are sandwiched between a pair of support plates, the outer surface of the support plate may be deformed to be locally convex. Such deformation of the support plate is undesirable because it causes a local change in the thermal resistance between the heater unit and the dielectric substrate.

[0007] 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 in which the heater layer and the bypass layer are connected by welding, yet deformation of the support plate can be prevented. [Means for solving the problem]

[0008] In order to solve the above problems, an electrostatic chuck according to the present invention includes a dielectric substrate and a heater unit for heating the dielectric substrate. The heater unit includes a heater layer that generates heat when supplied with electric power, a bypass layer having a portion welded to the heater layer, and a pair of support plates that sandwich the heater layer and the bypass layer therebetween. When the welded portion between the heater layer and the bypass layer is defined as a welded portion, at least one of the pair of support plates has an opening formed at a position facing the welded portion.

[0009] In an electrostatic chuck having such a configuration, the welded portion is housed inside the opening formed in the support plate, so that even if the welded portion is locally raised, the support plate will not be deformed by the raised portion.

[0010] In the electrostatic chuck according to the present invention, it is also preferable that the welded portion extends in a predetermined direction, and that the opening formed at the position opposite the welded portion also extends in the predetermined direction. By forming the opening in accordance with the shape of the welded portion, the size of the opening can be kept to a minimum necessary. Note that the welded portion "extending in a predetermined direction" refers not only to a case where a single welded portion extends long along the predetermined direction, but also to a case where a plurality of (e.g., circular) welded portions are lined up in the predetermined direction.

[0011] In the electrostatic chuck according to the present invention, it is also preferable that an opening is formed in both of the pair of support plates. With such a configuration, deformation of not only one but both of the support plates can be prevented. Effect of the Invention

[0012] According to the present invention, it is possible to provide an electrostatic chuck in which the heater layer and the bypass layer are connected by welding, and deformation of the support plate can be prevented. [Brief description of the drawings]

[0013] [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] FIG. 2 is an exploded view showing a schematic configuration of a heater unit. [Diagram 3] 5A to 5C are diagrams illustrating examples of arrangement of sub-heater layers in a heater unit. [Figure 4] FIG. 1 is a diagram showing the configuration of one sub-heater layer. [Diagram 5] 5A to 5C are diagrams showing examples of the arrangement of main heater layers in a heater unit. [Figure 6]FIG. 1 is a diagram showing the configuration of one main heater layer. [Figure 7] FIG. 13 is a diagram for explaining the role of a bypass layer, etc. [Figure 8] FIG. 2 is a cross-sectional view showing a configuration of a welded portion and its surroundings in a heater unit. [Figure 9] FIG. 13 is a diagram showing an opening formed in a support plate. [Figure 10] 13A to 13C are diagrams for explaining other configurations of the heater unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] 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.

[0015] 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 an etching 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.

[0016] 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 heater unit 300.

[0017] 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 of the dielectric substrate 100 in semiconductor manufacturing equipment.

[0018] 1 of the dielectric substrate 100 is a "mounting surface" on which the substrate W is mounted. Also, a lower surface 120 of the dielectric substrate 100 in FIG. 1 is a "bonded surface" that is bonded to the heater unit 300 via a bonding layer 410. The viewpoint when the electrostatic chuck 10 is viewed from the side of the surface 110 along a direction perpendicular to the surface 110 will hereinafter be referred to as a "top view".

[0019] 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 arranged parallel to the surface 110. The material of the adsorption electrode 130 may be molybdenum, platinum, palladium, or the like, in addition to tungsten. 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, thereby adsorbing and holding the substrate W. As the configuration of the power supply path, various known configurations can be adopted. The adsorption electrode 130 may be provided as a so-called "monopolar" electrode as in this embodiment, or may be provided as two so-called "bipolar" electrodes.

[0020] As shown in Fig. 1, 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 (not shown). 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.

[0021] A seal ring 111 and dots 112 are provided on a surface 110 which is a mounting surface, and the above-mentioned space SP is formed around these.

[0022] The seal ring 111 is a wall that divides the space SP at the outermost position. The seal ring 111 forms part of the surface 110 and abuts against the substrate W. 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.

[0023] 1, 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 by digging down a part of the surface 110 to the position of the bottom surface 116.

[0024] 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 mounting 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.

[0025] The base plate 200 is a substantially disk-shaped member that supports the dielectric substrate 100 and the heater unit 300. The base plate 200 is formed of a metal material such as aluminum. The upper surface 210 of the base plate 200 in FIG. 1 is a "bonded surface" that is bonded to the heater unit 300 via a bonding layer 420.

[0026] A coolant flow path 250 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 250 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.

[0027] An insulating film may be formed on the surface of the base plate 200. For example, an alumina film formed by thermal spraying can be used as the insulating film. By covering the surface of the base plate 200 with the insulating film, the dielectric strength of the base plate 200 can be increased.

[0028] The heater unit 300 generates heat when power is supplied from an external source, and heats the dielectric substrate 100. As will be described later, the heater unit 300 is provided with a plurality of heat generating parts 331, etc., and the amount of heat generated by each of the heat generating parts 331, etc. can be individually adjusted. By individually adjusting the amount of heat generated by each part, the in-plane temperature distribution of the substrate W during processing can be made closer to uniform.

[0029] The heater unit 300 is sandwiched between the dielectric substrate 100 and the base plate 200 and is bonded to each of them. The heater unit 300 and the dielectric substrate 100 are bonded via a bonding layer 410, and the heater unit 300 and the base plate 200 are bonded via a bonding layer 420. The bonding layers 410 and 420 are layers formed by, for example, hardening a silicone adhesive. A plurality of particulate fillers (fillers) for increasing thermal conductivity are disposed inside each of the bonding layers. For example, particles mainly composed of alumina can be used as the filler.

[0030] A specific configuration of the heater unit 300 will be described. In FIG. 2, the configuration of the heater unit 300 is shown as a schematic exploded view. As shown in the figure, the heater unit 300 has a support plate 310 (310A), an insulating layer 320, a sub-heater layer 330, an insulating layer 340, a main heater layer 350, an insulating layer 360, a bypass layer 370, an insulating layer 380, a support plate 310 (310B), and a power supply section 390. In this embodiment, the sub-heater layer 330, the main heater layer 350, and the bypass layer 370 are arranged in this order from the top, but the arrangement order of these may be different from that of this embodiment.

[0031] The support plate 310 is a substantially disk-shaped member and is provided at each of the upper and lower ends of the heater unit 300 in FIG. 2. The support plate 310 provided at the upper end in FIG. 2 is also referred to as the "support plate 310A" below. The support plate 310 provided at the lower end in FIG. 2 is also referred to as the "support plate 310B" below. The pair of support plates 310A and 310B are members for reinforcing the entire heater unit 300 by sandwiching the entire sub-heater layer 330, the main heater layer 350, the bypass layer 370, etc. between them. In this embodiment, both the support plates 310A and 310B are made of metal, but may be made of other materials (e.g., insulating materials). As described later, the support plates 310A and 310B have openings 311 formed therein, but these are omitted from FIG. 2.

[0032] The insulating layer 320 is provided between the support plate 310A and the sub-heater layer 330, and serves to electrically connect the two. The insulating layer 320 also serves to physically bond the two. In this embodiment, the insulating layer 320 is a polyimide film, but it may be made of other materials. If the support plate 310A is made of an insulating material, it is possible to eliminate the insulating layer 320.

[0033] The sub-heater layer 330 is a part that generates heat when power is supplied from the outside. In Fig. 2, the sub-heater layer 330 is depicted as a single disk, but in reality, the sub-heater layer 330 is divided into a plurality of regions, and each region can be individually heated. The specific configuration of the sub-heater layer 330 will be described later.

[0034] The insulating layer 340 is provided between the sub-heater layer 330 and the main heater layer 350, and serves to electrically connect the two. The insulating layer 340 also serves to physically bond the two. In this embodiment, the insulating layer 340 is a polyimide film, but it may be made of other materials.

[0035] The main heater layer 350, like the sub-heater layer 330 described above, is a part that receives power from an external source and generates heat. In Fig. 2, the main heater layer 350 is depicted as a single disk, but in reality, the main heater layer 350 is divided into a plurality of regions, and each region can be individually heated. The specific configuration of the main heater layer 350 will be described later.

[0036] The main heater layer 350 has a larger heat generation amount than the sub-heater layer 330 described above. The main heater layer 350 is intended to increase the temperature of the entire dielectric substrate 100 in a short period of time. The sub-heater layer 330 is intended to adjust the temperature of each part of the dielectric substrate 100 and make the in-plane temperature distribution of the substrate W closer to uniform. In this manner, in this embodiment, two heater layers are provided separately according to their respective roles. Alternatively, a configuration in which only one heater layer is provided may be used.

[0037] The insulating layer 360 is provided between the main heater layer 350 and the bypass layer 370, and serves to electrically connect the two layers. The insulating layer 360 also serves to physically bond the two layers. In this embodiment, the insulating layer 360 is a polyimide film, but it may be made of other materials.

[0038] The bypass layer 370 is a layer for electrically connecting a power supply part 390, which will be described later, to the sub-heater layer 330 and the main heater layer 350. In FIG. 2, the bypass layer 370 is depicted as a single disk, but in reality, the bypass layer 370 is divided into a plurality of parts. By providing the bypass layer 370 in the middle of the electric path connected to the sub-heater layer 330, etc., it becomes possible to adjust the position of the power supply part 390, etc. A part of the bypass layer 370 is welded to the sub-heater layer 330 or the main heater layer 350. The configuration of the welded part will be described later.

[0039] The insulating layer 380 is provided between the bypass layer 370 and the support plate 310B, and serves to electrically connect the two. The insulating layer 380 also serves to physically connect the two. In this embodiment, the insulating layer 380 is a polyimide film, but it may be made of other materials. If the support plate 310B is made of an insulating material, it is possible to eliminate the insulating layer 380.

[0040] The power supply unit 390 is a part that receives, from the outside, the power required to heat the sub-heater layer 330 and the like. In this embodiment, the power supply unit 390 is formed as a long, thin rod-shaped plug, one end of which is connected to the bypass layer 370. A plurality of power supply units 390 are provided according to the number of bypass layers 370, but only two of them are shown in FIG. 2. Through holes (not shown) are formed in the base plate 200 at positions corresponding to the power supply units 390, and the power supply units 390 are inserted through the through holes.

[0041] The structure of the sub-heater layer 330 will now be described. As described above, the sub-heater layer 330 is divided into a plurality of regions, and each region can be individually heated. Fig. 3 shows an example of how the sub-heater layer 330 is divided from a top view. In this example, the sub-heater layer 330 is divided into a total of 24 regions HA.

[0042] The sub-heater layer 330 is configured as a linear heat generating portion 331, which is routed individually in each region HA. Fig. 4 shows an example of the heat generating portion 331 routed in one region HA. In each region HA, one linear heat generating portion 331 is routed along a path that passes uniformly through almost the entire range.

[0043] Circular pad portions 332, 333 are formed on both ends of the heat generating portion 331. The heat generating portion 331 and the pad portions 332, 333 are formed, for example, by etching a thin metal foil, and the whole of them functions as one sub-heater layer 330. In other words, one sub-heater layer 330 is provided for each of the 24 regions HA in total.

[0044] The structure of the main heater layer 350 will now be described. Like the sub-heater layer 330, the main heater layer 350 is also divided into multiple regions, and each region can generate heat individually. Figure 5 shows an example of how the main heater layer 350 is divided from a top view. In this example, the main heater layer 350 is divided into a total of three regions HB.

[0045] The main heater layer 350 is configured as a linear heat generating portion 351, which is routed individually in each region HB. Figure 6 shows an example of the heat generating portion 351 routed in one region HB. In each region HB, one linear heat generating portion 351 is routed in a path that passes uniformly through almost the entire range of the region.

[0046] Circular pad portions 352, 353 are formed on both ends of the heat generating portion 351. The heat generating portion 351 and the pad portions 352, 353 are formed, for example, by etching a thin metal foil, and the whole of them functions as one main heater layer 350. In other words, one main heater layer 350 is provided for each of the three regions HB.

[0047] 7 shows, as a schematic perspective view, two regions HA, two sub-heater layers 330 arranged therein, and a bypass layer 370 connected to the sub-heater layers 330. One of the two regions HA shown in FIG. 3 is also referred to as "region HA1" below. The other region HA is also referred to as "region HA2" below. Note that the shapes of the heat generating portion 331 and the like shown in FIG. 7 are schematic and differ from the actual shapes.

[0048] The bypass layer 370 is divided into a plurality of parts. In FIG. 7, only three of the bypass layer 370 divided into a plurality of parts are shown. Of the three bypass layers 370 divided into three, the one marked with the reference symbol "371" in FIG. 7 is disposed at a position overlapping only one region HA in top view. In other words, each bypass layer 370 is disposed at a position directly below each region HA. The portion of the bypass layer 370 disposed in this manner is hereinafter also referred to as the "bypass layer 371."

[0049] 7 is disposed at a position overlapping both the region HA1 and the region HA2 in top view. The portion of the bypass layer 370 disposed in this manner is hereinafter also referred to as the "bypass layer 372."

[0050] In the sub-heater layer 330 arranged in the region HA1, a pad portion 332 at one end of a heat generating portion 331 is electrically connected to a bypass layer 371 located immediately below it. A pad portion 333 at the other end of the heat generating portion 331 is electrically connected to the bypass layer 372.

[0051] The same is true for the sub-heater layer 330 arranged in region HA2, where a pad portion 332 at one end of the heat generating portion 331 is electrically connected to the bypass layer 371 located immediately below it. A pad portion 333 at the other end of the heat generating portion 331 is electrically connected to the bypass layer 372.

[0052] The electrical connection between the above-mentioned components is achieved by welds 301, which will be described later. To make the configuration easier to understand, in Fig. 7, each weld 301 is depicted diagrammatically as a rod-like member extending linearly, but the actual shape of weld 301 is different from this.

[0053] One end of a power supply unit 390 is connected to each of the bypass layers 371 from below in Fig. 7. A voltage is individually applied to each of the power supply units 390 from an external DC power supply. Similarly, one end of a power supply unit 390 is connected to the bypass layer 372 from below in Fig. 7. This power supply unit 390 is grounded.

[0054] As described above, one pad portion 332 of each of the sub-heater layers 330 provided for each region HA is connected to an individual DC power supply via the bypass layer 371, and the other pad portion 333 is grounded via the common bypass layer 372. The other sub-heater layers 330 not shown in Fig. 7 are also connected to a DC power supply or the like in a similar configuration. With this configuration, it is possible to individually supply power to each of the multiple sub-heater layers 330 provided and adjust the amount of heat generated at each portion.

[0055] It is also possible to supply power to the sub-heater layer 330 directly from the power supply unit 390 without passing through the bypass layer 370. However, by using a configuration in which power is supplied through the bypass layer 370 as in this embodiment, it is possible to increase the degree of freedom in arranging the power supply units 390 and to consolidate the power supply units 390 that are grounded into one.

[0056] The supply of power to each main heater layer 350 is achieved by the same configuration as above. The specific configuration is the same as that shown in Fig. 7, so description and illustration thereof will be omitted. The bypass layer 370 connected to the sub-heater layer 330 and the bypass layer 370 connected to the main heater layer 350 may be disposed at the same height position (the position of the bypass layer 370 shown in Fig. 2) as in this embodiment, but may also be disposed at different height positions.

[0057] As described above, in the heater unit 300, the sub-heater layer 330 and the bypass layer 370 are welded and electrically connected to each other. Such a welded portion is hereinafter also referred to as a "welded portion 301."

[0058] Fig. 8 is a cross-sectional view showing the configuration of a welded portion 301 and its vicinity in the heater unit 300. As shown in Fig. 8, in a part of the heater unit 300, the sub-heater layer 330 and the bypass layer 370 are directly abutted against each other without the insulating layers 340, 360 and the main heater layer 350 therebetween, and then the two are integrally connected by, for example, resistance spot welding. In many cases, the welded portion 301 is in a locally raised state as shown in Fig. 8 due to the melting of the respective members during welding, etc.

[0059] In this embodiment, two welds 301 are formed in positions close to each other as shown in Fig. 8. That is, two welds 301 are actually formed in each position as shown in Fig. 7. The number of welds 301 arranged together so as to be close to each other may be only one, or may be three or more. The number and intervals of welds 301 may be appropriately set according to the welding method to be adopted, etc.

[0060] After the sub-heater layer 330 and the bypass layer 370 are welded as described above, the sub-heater layer 330 and the like are sandwiched between a pair of support plates 310. The welded portion 301 is raised as described above, and protrudes toward the upper side of the insulating layer 320 and the lower side of the insulating layer 380 in Fig. 8. Therefore, depending on the size of the welded portion 301, when the entire sub-heater layer 330 and the like are sandwiched between the pair of support plates 310, the welded portion 301 may come into contact with the support plates 310, and the outer surface of the support plates 310 may be deformed to become locally convex.

[0061] When the support plate 310 is deformed, the bonding layers 410, 420 (see FIG. 1) become thinner in that portion. As a result, the thermal resistance between the heater unit 300 and the dielectric substrate 100 and the thermal resistance between the heater unit 300 and the base plate 200 become locally small, which undesirably increases the in-plane temperature variation of the substrate W.

[0062] Therefore, in the electrostatic chuck 10 according to this embodiment, an opening 311 is formed in the support plate 310 at a position facing the welded portion 301. As shown in Fig. 9(A) , the opening 311 in this embodiment is a circular opening, and two welded portions 301 are accommodated inside one opening 311 when viewed from above.

[0063] The heater unit 300 is provided with a plurality of welds 301 that connect the sub-heater layer 330 and the bypass layer 370. In the support plate 310, openings 311 similar to those in FIG. 8 are formed at all positions that overlap with the welds 301 in a top view. That is, all the welds 301 are accommodated inside the openings 311 formed in the support plate 310. Since the welds 301 do not come into contact with the support plate 310, even if the welds 301 are locally raised, the support plate 310 will not be deformed by this.

[0064] The opening 311 may be formed in both of the pair of support plates 310A, 310B, or may be formed in only one of them. However, forming the opening 311 in both of the support plates 310A, 310B as in this embodiment is more preferable because it can prevent deformation of the support plate 310 on both sides of the heater unit 300.

[0065] In the case where two welds 301 are present in positions close to each other and the two welds 301 as a whole extend in a predetermined direction as in this embodiment, the shape of the opening 311 may be a shape extending in the same direction (the above-mentioned "predetermined direction") as in the example of Fig. 9(B). Also, in the case where only one weld 301 is present and the shape of the weld 301 extends in a predetermined direction as in the example of Fig. 9(C), the shape of the opening 311 may be a shape extending in the same direction as in the above.

[0066] In other words, when welded portion 301 extends in a predetermined direction, opening 311 formed at a position opposite welded portion 301 may be formed so as to also extend in the predetermined direction. By forming opening 311 according to the shape of welded portion 301, the size of welded portion 301 can be kept to a necessary minimum.

[0067] In addition, the expression "extending in a predetermined direction" of the welded portion 301 includes not only the case where a single welded portion 301 extends long along the predetermined direction (FIG. 9(C)), but also the case where multiple welded portions 301 are lined up in the predetermined direction (FIG. 9(B)).

[0068] The above describes the configuration of the connection portion between the sub-heater layer 330 and the bypass layer 370, but the configuration of the connection portion between the main heater layer 350 and the bypass layer 370 is similar to that described above. Although not shown in the figures, the main heater layer 350 and the bypass layer 370 are also connected by a welded portion 301, and an opening 311 similar to that shown in Figures 8 and 9 is formed in the portion of the support plate 310 facing this welded portion 301.

[0069] Other configurations of the heater unit 300 will be described. As shown in Fig. 10(A), a through hole 302 penetrating the entire heater unit 300 is formed in a portion of the heater unit 300 other than the opening 311. Examples of such through hole 302 include a hole for inserting a lift pin provided in a semiconductor manufacturing device, a gas hole for introducing helium gas into the space SP, and the like.

[0070] 10(A), none of the members constituting heater unit 300, such as insulating layer 320 and sub-heater layer 330, protrude inward from through hole 302, and the entire inner surface of through hole 302 is a substantially cylindrical surface. In this configuration, each member, such as insulating layer 320, does not impede the movement of the lift pin or helium gas passing through through hole 302.

[0071] 10(B), all of the members constituting heater unit 300, except for support plate 310, protrude inward from the inner surface of through hole 302. Such protruding portions are hereinafter also referred to as "protruding portion 303." When viewed from above, protruding portion 303 protrudes in a continuous ring shape inside through hole 302.

[0072] In such a configuration, electrical contact between support plate 310A and support plate 310B is reliably prevented by the presence of protrusion 303. Since the potentials of support plate 310A and support plate 310B do not fluctuate suddenly due to contact, it is possible to reliably prevent a situation in which plasma becomes unstable in the semiconductor manufacturing equipment.

[0073] In addition, when the configuration of FIG. 10B is used, it is preferable to keep the amount of protrusion of the protruding portion 302 small so as not to impede the movement of the lift pin or helium gas passing through the through hole 302.

[0074] A through hole 302 as shown in FIG. 10(A) and a through hole 302 as shown in FIG. 10(B) may be mixed in one heater unit 300.

[0075] 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]

[0076] 10: Electrostatic chuck 100: Dielectric substrate 300: Heater unit 330: Sub-heater layer 350: Main heater layer 370: Bypass layer 310,310A,310B: Support plate 311:Aperture

Claims

1. A dielectric substrate; a heater unit for heating the dielectric substrate, The heater unit comprises: A heater layer that generates heat when supplied with power; a bypass layer, a portion of which is welded to the heater layer; a pair of support plates sandwiching the heater layer and the bypass layer therebetween, When the portion where the heater layer and the bypass layer are welded is defined as a welded portion, At least one of the pair of support plates has an opening formed at a position facing the welded portion.

2. The weld extends in a predetermined direction, 2. The electrostatic chuck according to claim 1, wherein the opening formed at a position opposite the welded portion also extends in the predetermined direction.

3. 2. The electrostatic chuck according to claim 1, wherein the openings are formed in both of the pair of support plates.

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