Electrostatic chuck

Abstract

To provide an electrostatic chuck capable of restraining occurrence of dielectric breakdown in a bypass portion.SOLUTION: An electrostatic chuck 10 includes a dielectric substrate 100 and a heater unit 300 for heating the dielectric substrate 100. A heater unit 300 includes a plurality of heat generating portions 351, a plurality of heat generating portions 331 provided at a different height from the heat generating portions 351, a plurality of first bypass portions 370A connected to the respective heat generating portions 351, and a plurality of second bypass portions 370B connected to the respective heat generating portions 331. A distance D10 between a pair of adjacent first bypass portions 370A is larger than a distance D20 between a pair of adjacent second bypass portions 370B.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 within 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 have already been put to practical use. The heater may be provided inside the dielectric substrate, or may be provided as a unit between the dielectric substrate and the base plate, as described in Patent Document 1 below. [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 heater has a heat generating portion which is a conductor wired in a linear shape. When power is supplied from the outside and a current flows through the heat generating portion, Joule heat is generated in the heat generating portion. In order to make it possible to individually adjust the temperature of each portion of the dielectric substrate, the heat generating portion of the heater is wired individually in each of the multiple regions.

[0006] The inventors have been studying the possibility of arranging multiple heat generating parts in multiple layers at different heights, rather than in a single layer. Each layer is divided into multiple regions, and the heat generating parts in each region can be individually heated. With this configuration, it is possible to provide, for example, a layer that functions as a "main heater" with a large amount of heat generated per unit area and a small number of divisions, and a layer that functions as a "sub-heater" with a small amount of heat generated per unit area and a large number of divisions.

[0007] It is preferable to further provide a bypass section in such a heater having a large number of heat generating sections. The bypass section electrically connects the heat generating section and the power supply section that receives power from an external source. A plurality of bypass sections are provided corresponding to the heat generating sections, and each bypass section becomes part of an electric path connected to each heat generating section. By providing the bypass section, it becomes possible to increase the degree of freedom in arranging the power supply section in the heater.

[0008] Among the multiple bypass sections, some are connected to sub-heaters that generate a small amount of heat, while others are connected to main heaters that generate a large amount of heat. The latter bypass sections are subjected to a higher voltage than the former bypass sections, so there is a higher possibility of dielectric breakdown occurring. However, no specific consideration has been given to the placement of the bypass sections to prevent dielectric breakdown.

[0009] The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrostatic chuck capable of suppressing the occurrence of dielectric breakdown in a bypass portion. [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 mounting surface on which an object to be attracted is mounted, and a heater for heating the dielectric substrate. When a position along a direction perpendicular to the mounting surface is defined as a height position, the heater has a plurality of first heat generating parts that generate heat by receiving power from an external source, a plurality of second heat generating parts that are provided at a height position different from the first heat generating parts and generate heat by receiving power from an external source, a plurality of first bypass parts connected to the respective first heat generating parts, and a plurality of second bypass parts connected to the respective second heat generating parts. The number of the first heat generating parts is smaller than the number of the second heat generating parts. The respective first bypass parts are provided at the same height position as each other. The respective second bypass parts are provided at the same height position as each other. The distance between a pair of adjacent first bypass parts is greater than the distance between a pair of adjacent second bypass parts.

[0011] The first heating section, which has a smaller number of divisions, is often used as a main heater that generates a large amount of heat per unit area, and the second heating section, which has a smaller number of divisions, is often used as a sub-heater that generates a small amount of heat per unit area. For this reason, in many cases, the voltage applied between the pair of first bypass sections is greater than the voltage applied between the pair of second bypass sections.

[0012] Therefore, in the electrostatic chuck, the distance between a pair of first bypass portions adjacent to each other at the same height position is configured to be greater than the distance between a pair of second bypass portions adjacent to each other at the same height position. By arranging the bypass portions in this manner, it is possible to suppress the occurrence of dielectric breakdown between the first bypass portions to which a high voltage is applied. Effect of the Invention

[0013] According to the present invention, it is possible to provide an electrostatic chuck capable of suppressing the occurrence of dielectric breakdown in a bypass portion. [Brief description of the drawings]

[0014] [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. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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".

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] The main heater layer 350 has a larger amount of heat generated per unit area 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 portion 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] The sub-heater layer 330 is configured as linear heat generating portions 331, which are individually routed in each region HA. That is, in this embodiment, a total of 24 heat generating portions 331 are provided.

[0046] 4 shows an example of a heat generating portion 331 routed in one area HA. ​​In each area HA, one linear heat generating portion 331 is routed along a path that passes uniformly through almost the entire area. The heat generating portion 331 is a portion that generates heat by receiving power from an external source, and corresponds to the "second heat generating portion" of this embodiment.

[0047] 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.

[0048] 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.

[0049] 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 four regions HB.

[0050] The main heater layer 350 is configured as a linear heat generating portion 351, which is individually routed in each region HB. That is, in this embodiment, a total of four heat generating portions 351 are provided.

[0051] 6 shows an example of heat generating portion 351 routed in one area HB. In each area HB, one linear heat generating portion 351 is routed along a path that passes uniformly through almost the entire area. Heat generating portion 351 is a portion that receives power from an external source and generates heat, and corresponds to the "first heat generating portion" of this embodiment. The number of heat generating portions 351 (four in total) is less than the number of heat generating portions 331 (24 in total).

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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."

[0056] 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."

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] Fig. 8 shows the overall configuration of the bypass layer 370. As described above, the bypass layer 370 is divided into multiple parts, each of which is connected to either the sub-heater layer 330 or the main heater layer 350. Note that the shape and number of each bypass layer 370 shown in Fig. 8 are schematic and differ from the actual shape and number. In the following description, each of the multiple divided bypass layers 370 is also referred to as a "bypass section."

[0065] In Fig. 8, the bypass portion denoted by the reference symbol "370A" is connected to the main heater layer 350. This bypass portion is also referred to as the "first bypass portion 370A" below. The first bypass portion 370A is welded and connected to the main heater layer 350 in the same configuration as that shown in Fig. 7. In the portions overlapping with the welded portions in top view, openings are formed in the insulating layer 360 between the main heater layer 350 and the first bypass portion 370A, and the main heater layer 350 and the first bypass portion 370A are directly connected through the openings.

[0066] In Fig. 8, the bypass portion denoted by the reference symbol "370B" is connected to the sub-heater layer 330. This bypass portion is also referred to as the "second bypass portion 370B" below. The second bypass portion 370B corresponds to the bypass layer 371 and the bypass layer 372 in the example of Fig. 7. Note that, among the multiple bypass layers shown in Fig. 7, all of those without reference symbols are the second bypass portion 370B.

[0067] For ease of explanation, a position along a direction perpendicular to surface 110 serving as the placement surface, that is, a position along the up-down direction in FIG. 1 and FIG. 2, will also be referred to as a "height position" below.

[0068] In this embodiment, the heat generating portion 351 (first heat generating portion) of the main heater layer 350 and the heat generating portion 331 (second heat generating portion) of the sub-heater layer 330 are disposed at different height positions. On the other hand, the heat generating portions 351 are disposed at the same height positions, and the first bypass portions 370A connected to the respective heat generating portions 351 are also disposed at the same height positions (height positions of the bypass layers 370). Similarly, the heat generating portions 331 are disposed at the same height positions, and the second bypass portions 370B connected to the respective heat generating portions 331 are also disposed at the same height positions (height positions of the bypass layers 370).

[0069] In this embodiment, the first bypass portion 370A and the second bypass portion 370B are disposed at the same height position. With such a configuration, the heater unit 300 can be made thinner overall, and its thermal resistance can be reduced. Instead of this embodiment, the first bypass portion 370A and the second bypass portion 370B may be disposed at different height positions. In other words, two or more bypass layers 370 may be provided at different height positions.

[0070] As described above, the main heater layer 350 is for increasing the temperature of the entire dielectric substrate 100 in a short period of time, and the sub-heater layer 330 is for adjusting the temperature of each portion of the dielectric substrate 100. The amount of heat generated per unit area of ​​the main heater layer 350 is greater than the amount of heat generated per unit area of ​​the sub-heater layer 330. The sub-heater layer 330 is divided into more regions than the main heater layer 350 in order to enable adjustment of the in-plane temperature distribution with high precision.

[0071] A larger voltage is applied to the heat generating portion 351 of the main heater layer 350 so as to increase the amount of heat generated. That is, the voltage applied to each heat generating portion 351 is greater than the voltage applied to each heat generating portion 331. Therefore, the voltage applied to the first bypass portion 370A is greater than the voltage applied to the second bypass portion 370B.

[0072] Therefore, if the distance between adjacent first bypass portions 370A is made too small, there is a possibility that dielectric breakdown will occur between them. On the other hand, if the distance between all bypass portions is made uniformly large in order to prevent dielectric breakdown, it will be impossible to arrange the necessary number of bypass portions within a limited area.

[0073] Therefore, in this embodiment, the distance between the bypass sections is made different depending on the location. Specifically, the distance D10 between a pair of first bypass sections 370A adjacent to each other at the same height position is made larger than the distance D20 between a pair of second bypass sections 370B adjacent to each other at the same height position. With this configuration, it is possible to suppress the occurrence of dielectric breakdown between the first bypass sections 370A to which a high voltage is applied. This configuration can also be adopted when the first bypass section 370A and the second bypass section 370B are arranged at different height positions.

[0074] In this embodiment, the distance D10 between a pair of adjacent first bypass portions 370A is the same regardless of the location. Similarly, the distance D20 between a pair of adjacent second bypass portions 370B is the same regardless of the location. However, there may be a configuration in which the distance D10 and the distance D20 are different depending on the location or direction. In this case, the bypass portions may be arranged so that D10>D20 is always satisfied regardless of the combination in which the distance D10 and the distance D20 are compared.

[0075] Furthermore, in this embodiment, the first bypass portion 370A and the second bypass portion 370B are provided at the same height position, and the distance D12 between the adjacent first bypass portion 370A and the second bypass portion 370B is made larger than the distance D20 between a pair of adjacent second bypass portions 370B. With this configuration, it is possible to suppress the occurrence of dielectric breakdown even between the first bypass portion 370A and the second bypass portion 370B that are adjacent to each other at the same height position.

[0076] In this embodiment, the distance D12 between the first bypass portion 370A and the second bypass portion 370B adjacent to each other is the same regardless of the location. Similarly, the distance D20 between a pair of the second bypass portions 370B adjacent to each other is the same regardless of the location. However, there may be a configuration in which the distance D12 and the distance D20 are different depending on the location or direction. In this case, each bypass portion may be arranged so that D12>D20 is always satisfied regardless of the combination in which the distance D12 and the distance D20 are compared.

[0077] In the above, a configuration has been described in which a heater for heating the dielectric substrate 100 is provided outside the dielectric substrate 100 in a state where it is unitized as the heater unit 300. However, the above-described configuration can also be applied to a configuration in which a heater is provided inside the dielectric substrate 100.

[0078] That is, the sub-heater layer 330, the main heater layer 350, and the bypass layer 370 similar to those of the present embodiment may each be embedded inside the dielectric substrate 100, similar to the attraction electrode 130. In this case, the connection between the sub-heater layer 330 and the bypass layer 370 may be made, for example, through holes (vias) filled with a conductor, rather than by welding. Even in such an embodiment, the same effects as those of the present embodiment can be achieved.

[0079] 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]

[0080] 10: Electrostatic chuck 100: Dielectric substrate 110: Face 300: Heater unit 331, 351: Heat generating part 370A: First bypass section 370B: Second bypass section

Claims

1. a dielectric substrate having a mounting surface on which an object to be attached is placed; a heater for heating the dielectric substrate, When the position along the direction perpendicular to the placement surface is defined as the height position, The heater is A plurality of first heat generating portions that generate heat by receiving power from an external source; A plurality of second heat generating portions are provided at a different height from the first heat generating portions and generate heat by receiving power from an external source; A plurality of first bypass portions connected to the respective first heat generating portions; a plurality of second bypass portions connected to the second heat generating portions, the number of the first heat generating portions is smaller than the number of the second heat generating portions, The first bypass portions are provided at the same height position as each other, The second bypass portions are provided at the same height position as each other, a distance between a pair of adjacent first bypass portions is greater than a distance between a pair of adjacent second bypass portions.

2. 2. The electrostatic chuck according to claim 1, wherein the first bypass portion and the second bypass portion are provided at the same height position.

3. 3. The electrostatic chuck according to claim 2, wherein a distance between the first bypass portion and the second bypass portion adjacent to each other is greater than a distance between a pair of the second bypass portions adjacent to each other.

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