Electrostatic chuck

Abstract

To provide an electrostatic chuck capable of restraining occurrence of dielectric breakdown between a heater layer and a bypass layer.SOLUTION: An electrostatic chuck 10 includes a dielectric substrate 100 and a heater unit 300. The heater unit 300 includes a main heater layer 350, an insulating layer 360, and a bypass layer 370 laminated on the main heater layer 350 via the insulating layer 360. When a first portion P1 defines a portion where the bypass layer 370 and the main heater layer 350 do not overlap each other and are spaced apart from each other through a gap D1 in top view, and a second portion P2 defines a portion different from the first portion P1, where the insulating layer 360 and the main heater layer 350 overlap each other, the gap D1 in the first portion P1 is larger than the thickness D2 of the insulating layer 360 in the second portion P2.SELECTED DRAWING: Figure 10

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 high-precision 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 configuration in which a heater is 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 insulating layers such as polyimide sheets, it becomes possible to relatively easily attach it to an electrostatic chuck. When unitizing a heater, it is preferable to provide a bypass layer in addition to the heater layer. The bypass layer is a layer for electrically connecting between a power supply part that receives power from the outside and the heater layer. By providing the bypass layer, it becomes possible to increase the degree of freedom in the arrangement of the power supply part in the heater unit. When manufacturing such a heater unit, the heater layer, the bypass layer, and the insulating layer are laminated, and then the entirety of these is pressed to be integrated.

[0006] An insulating layer is sandwiched between the heater layer and the bypass layer. In a top view, in a portion where the heater layer and the bypass layer are separated from each other, a force is applied to the insulating layer from the bypass layer on the lower side, while a force in the opposite direction is applied from the heater layer on the upper side. In other words, a shear force is applied to the insulating layer by being sandwiched between the heater layer and the bypass layer. If the shear force becomes too large, a part of the insulating layer is deformed and thinned, and there is a possibility that insulation breakdown occurs between the heater layer and the bypass layer.

[0007] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide an electrostatic chuck that can suppress the occurrence of dielectric breakdown between a heater layer and a bypass layer. [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 having a mounting surface on which an object to be attracted is mounted, and a heater unit bonded to the dielectric substrate and configured to heat the dielectric substrate. The heater unit includes a heater layer that generates heat when power is supplied from an external source, an insulating layer, and a bypass layer that is laminated on the heater layer via the insulating layer. When viewed from a direction perpendicular to the mounting surface, a first portion is a portion where the bypass layer and the heater layer do not overlap each other and are separated from each other with a gap therebetween, and a second portion is a portion different from the first portion where the insulating layer and the heater layer overlap each other, the gap in the first portion is larger than the thickness of the insulating layer in the second portion.

[0009] In such an electrostatic chuck, when viewed from a direction perpendicular to the mounting surface (i.e., viewed from above), the gap between the heater layer and the bypass layer in the first portion is larger than the thickness of the insulating layer in the second portion. In such a configuration, even if a shear force is applied to the insulating layer between the heater layer and the bypass layer, the thickness of the insulating layer hardly changes from its initial thickness (specifically, the thickness of the insulating layer in the second portion). Therefore, it is possible to suppress the occurrence of dielectric breakdown through the insulating layer. Effect of the Invention

[0010] According to the present invention, it is possible to provide an electrostatic chuck capable of suppressing the occurrence of dielectric breakdown between a heater layer and a bypass layer. [Brief description of the drawings]

[0011] [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 diagram showing the configuration of a bypass layer. [Figure 9] FIG. 4 is a diagram showing the positional relationship between a bypass layer and a main heater layer when viewed from above. [Figure 10] FIG. 3 is a cross-sectional view illustrating a schematic configuration of a first portion of a heater unit. [Figure 11] FIG. 4 is a diagram showing the positional relationship between a bypass layer and a main heater layer when viewed from above. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] 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.

[0013] 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 to be attracted is, for example, a silicon wafer. The electrostatic chuck 10 may be used in an apparatus other than a semiconductor manufacturing apparatus.

[0014] 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.

[0015] 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.

[0016] 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".

[0017] 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.

[0018] As shown in Fig. 1, a space SP is formed between the dielectric substrate 100 and the substrate W. When a process such as etching 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 temperature adjustment gas supplied to the space SP may be a type of gas other than helium.

[0019] 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.

[0020] The seal ring 111 is a wall that divides the space SP at the outermost position. The upper end of the 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] A coolant flow path 250 for flowing a coolant is formed inside the base plate 200. When a process such as etching 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.

[0025] 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.

[0026] 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.

[0027] The heater unit 300 is sandwiched between the dielectric substrate 100 and the base plate 200 and 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.

[0028] 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.

[0029] 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 "support plate 310A" below. The support plate 310 provided at the lower end in FIG. 2 is also referred to as "support plate 310B" below. The support plate 310A is a portion bonded to the dielectric substrate 100 via a bonding layer 410, and the support plate 310B is a portion bonded to the base plate 200 via a bonding layer 420.

[0030] The pair of support plates 310A, 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, 310B are made of metal, but they may be made of other materials (e.g., insulating materials). Note that, although a plurality of through holes are formed in each of the members constituting the heater unit 300, such as the support plate 310, for the purpose of passing lift pins through, etc., they are not shown in FIG. 2.

[0031] The insulating layer 320 is provided between the support plate 310A and the sub-heater layer 330, and serves to electrically insulate them from each other. The insulating layer 320 also serves to physically bond them together. In this embodiment, the insulating layer 320 is a polyimide film, but it may contain a component other than polyimide, or may be made of a material other than polyimide. When the support plate 310A is made of an insulating material, it is possible to eliminate the insulating layer 320.

[0032] 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.

[0033] The insulating layer 340 is provided between the sub-heater layer 330 and the main heater layer 350, and serves to electrically insulate the two layers from each other. The insulating layer 340 also serves to physically bond the two layers together. In this embodiment, the insulating layer 340 is a polyimide film, but it may contain a component other than polyimide, or may be made of a material other than polyimide.

[0034] 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.

[0035] 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.

[0036] The insulating layer 360 is provided between the main heater layer 350 and the bypass layer 370, and serves to electrically insulate the two layers from each other. The insulating layer 360 also serves to physically bond the two layers together. In this embodiment, the insulating layer 360 is a polyimide film, but it may contain a component other than polyimide, or may be made of a material other than polyimide.

[0037] The bypass layer 370 is a layer for electrically connecting a power supply unit 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, as shown in FIG. 8, the bypass layer 370 is divided into a plurality of pieces. 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 unit 390, etc. Each of the divided bypass layers 370 has a portion welded to the sub-heater layer 330 or the main heater layer 350.

[0038] The insulating layer 380 is provided between the bypass layer 370 and the support plate 310B, and serves to electrically insulate the two. The insulating layer 380 also serves to physically bond the two. In this embodiment, the insulating layer 380 is a polyimide film, but it may contain a component other than polyimide, or may be made of a material other than polyimide. If the support plate 310B is made of an insulating material, it is possible to eliminate the insulating layer 380.

[0039] 2 are laminated, the entire assembly is pressurized and heated, and the entire assembly is bonded together via the insulating layer 320, which is a polyimide film, and the like, to form an integrated unit.

[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] 4 is a schematic view and differs from the actual shape of the heat generating portion 331. The same applies to the positions of the pad portions 332 and 333.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 6 is a schematic view of the heat generating portion 351, and differs from the actual shape. The same applies to the positions of the pad portions 352 and 353.

[0049] 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. 7 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.

[0050] As described above, the bypass layer 370 is divided into a plurality of parts. In FIG. 7, only three of the plurality of divided bypass layers 370 are shown. Of the three divided bypass layers 370, 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 of the bypass layers 370 is disposed at a position directly below each of the regions HA. The portion of the bypass layer 370 disposed in this manner is hereinafter also referred to as the "bypass layer 371."

[0051] 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."

[0052] 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.

[0053] 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.

[0054] The electrical connection of each part as described above is realized by welding the upper and lower layers together. In order to make the configuration easier to understand, in Fig. 7, each welded part is depicted as a rod-shaped member (parts marked with reference numeral 301) extending linearly, but the actual shape of the welded part is different from this. In addition, in the parts overlapping with each welded part in top view, openings are formed in each layer (insulating layer 340, main heater layer 350, and insulating layer 360) between the sub-heater layer 330 and the bypass layer 370, and the sub-heater layer 330 and the bypass layer 370 are directly connected through the openings.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] The supply of power to each of the main heater layers 350 is achieved by the same configuration as above. The specific configuration is the same as that shown in Fig. 7, so the description and illustration thereof will be omitted.

[0059] Fig. 8 shows the overall configuration of the bypass layer 370. As described above, the bypass layer 370 is divided into a plurality of parts, each of which is connected to either the sub-heater layer 330 or the sub-heater layer 330. Note that the shape of each bypass layer 370 shown in Fig. 8 is schematic and differs from the actual shape.

[0060] In Fig. 8, the portion denoted by the reference symbol "370A" is a portion of the bypass layer 370 that is connected to the sub-heater layer 330. This portion is also referred to as "bypass layer 370A" below. The bypass layer 370A corresponds to the bypass layer 371 and the bypass layer 372 in the example of Fig. 7.

[0061] In Fig. 8, the portion marked with the reference symbol "370B" is a portion of the bypass layer 370 that is connected to the main heater layer 350. This portion is also referred to as the "bypass layer 370B" below. The bypass layer 370B is welded and connected to the main heater layer 350 in a configuration similar to that shown in Fig. 7. In the portions that overlap with the welds in top view, openings are formed in the insulating layer 360 between the main heater layer 350 and the bypass layer 370B, and the main heater layer 350 and the bypass layer 370B are directly connected through the openings.

[0062] The bypass layer 370B configured as above is laminated on the main heater layer 350 via the insulating layer 360, and can be said to be a layer with a portion electrically connected (by welding) to the main heater layer 350. The bypass layer 370A described above is similar, and the bypass layer 370A is laminated on the sub-heater layer 330 via the insulating layer 360, etc., and can be said to be a layer with a portion electrically connected (by welding) to the sub-heater layer 330.

[0063] The bypass layer 370A connected to the sub-heater layer 330 and the bypass layer 370B 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, or may be disposed at different height positions.

[0064] Most of the main heater layer 350 overlaps with the bypass layer 370 in top view, but there are also parts that do not overlap with the bypass layer 370. FIG. 9 shows an example of the positional relationship between the two in top view. The part marked with the symbol "P1" in the figure is a part where the bypass layer 370 and the main heater layer 350 do not overlap with each other in top view, and are separated from each other with a gap D1. This part is also referred to as the "first part P1" below. The part marked with the symbol "P2" is a part different from the above-mentioned first part P1, and is a part where the insulating layer 360 and the main heater layer 350 overlap with each other. This part is also referred to as the "second part P2" below. The bypass layer 370 shown in FIG. 9 may be either the bypass layer 370A or 370B.

[0065] 10 shows a cross section of the first portion P1 and its neighboring portion in FIG. 9 cut perpendicularly to the surface 110, which is the mounting surface. As described above, when manufacturing the heater unit 300, the entire unit is pressurized with each layer stacked. At this time, an upward force is applied to the insulating layer 360 from the bypass layer 370 on the lower side in FIG. 10, and a downward force is applied from the main heater layer 350 on the upper side. That is, a shear force is applied to the insulating layer 360 of the first portion P1 by being sandwiched between the main heater layer 350 and the bypass layer 370. By receiving such a shear force, the insulating layer 360 is deformed as shown in FIG. 10.

[0066] As the gap D1 between the bypass layer 370 and the main heater layer 350 becomes smaller, the insulating layer 360 approaches a state similar to that of being cut with scissors, and the above-mentioned shear force applied to the insulating layer 360 becomes larger. If the shear force becomes too large, a part of the insulating layer 360 becomes deformed and thin, increasing the possibility of dielectric breakdown occurring between the bypass layer 370 and the main heater layer 350.

[0067] Therefore, in the heater unit 300 according to this embodiment, the bypass layer 370, the main heater layer 350, and the like are arranged in such a way that the gap D1 does not become too small. Specifically, the gap D1 in the first portion P1 is larger than the thickness D2 of the insulating layer 360 in the second portion P2. The thickness D2 can be said to be the initial thickness of the insulating layer 360 when no shear force is applied. The thickness of the insulating layer 360 is approximately uniformly D2 in the portions other than the first portion P1. Therefore, even in the portion overlapping with the bypass layer 370 in a top view as shown in FIG. 10, the thickness of the insulating layer 360 is approximately equal to D2.

[0068] In the above-described configuration where D1>D2, even if the insulating layer 360 is deformed by a shearing force as shown in Fig. 10, the thickness of the insulating layer 360 at the first portion P1 hardly changes from the initial thickness D2. Therefore, the occurrence of dielectric breakdown through the insulating layer 360 can be suppressed.

[0069] The relationship between the gap D1 and the thickness D2 as described above always holds, with some exceptions, regardless of the selection of the first portion P1. That is, in a portion where the bypass layer 370 and the main heater layer 350 do not overlap each other in a top view and a gap is formed between them, D1>D2 holds as a rule.

[0070] The above-mentioned "exception" refers to a portion where the edge of the bypass layer 370 and the edge of the main heater layer 350 intersect with each other in top view. An example of such a portion is shown diagrammatically in Fig. 11. In the portion indicated by reference symbol P3 in Fig. 11, the edge of the bypass layer 370 and the edge of the main heater layer 350 intersect with each other, and the angle between them is θ.

[0071] In the heater unit 300 according to this embodiment, the bypass layer 370, the main heater layer 350, and the like are arranged so that the angle θ is 30 degrees or more at all the parts where the edges of the bypass layer 370 and the main heater layer 350 cross each other. By crossing the edges at a sufficiently large angle, the range where the shear force is applied to the insulating layer 360 is reduced, and the effect of the shear force can be suppressed to a negligible level. In other words, it is possible to prevent the insulating layer 360 from being subjected to a force like that of cutting with scissors. This makes it possible to prevent the insulating layer 360 from being thinned or having its insulation breakdown even in parts where it is difficult to sufficiently separate the bypass layer 370 and the main heater layer 350.

[0072] As mentioned above, the arrangement order of the main heater layer 350 and the like may be different from that shown in Fig. 2. Regardless of the arrangement order, the positional relationship between the bypass layer 370 and the main heater layer 350 as described above can be applied to any pair of conductor layers (e.g., the bypass layer 370 and the sub-heater layer 330) stacked with an insulating layer sandwiched therebetween.

[0073] 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]

[0074] 10: Electrostatic chuck 100: Dielectric substrate 110: Face 300: Heater unit 330: Sub-heater layer 350: Main heater layer 320, 340, 360, 380: Insulating layer 370: Bypass layer P1: 1st part P2: 2nd part D1: Gap D2: Thickness

Claims

1. a dielectric substrate having a mounting surface on which an object to be attached is placed; a heater unit joined to the dielectric substrate and configured to heat the dielectric substrate, The heater unit includes: A heater layer that generates heat by receiving power from an external source; An insulating layer; a bypass layer laminated on the heater layer via the insulating layer, When viewed from a direction perpendicular to the placement surface, a first portion is a portion where the bypass layer and the heater layer do not overlap each other and are separated from each other with a gap therebetween; When a portion different from the first portion, where the insulating layer and the heater layer overlap each other, is defined as a second portion, The electrostatic chuck, wherein the gap in the first portion is greater than a thickness of the insulating layer in the second portion.

2. When viewed from a direction perpendicular to the placement surface, 2. The electrostatic chuck according to claim 1, wherein an angle between an edge of said bypass layer and an edge of said heater layer at a portion where the edge intersects with each other is 30 degrees or more.

3. 10. The electrostatic chuck of claim 1, wherein the insulating layer comprises a polyimide.

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