Electrostatic chuck

Abstract

To provide an electrostatic chuck capable of simplifying the circuit configuration for temperature control.SOLUTION: An electrostatic chuck 10 comprises a dielectric substrate 100 and a heater unit 300 for heating the dielectric substrate 100. The heater unit 300 comprises a heating section 331 which is a conductor wound in a linear configuration and generates heat when supplied with power from an external source. In the top view, the heating section 331 is individually routed in each of a plurality of regions HA. The plurality of regions HA comprises a first region HA11 and a second region HA12. When the electrical resistance value of the heating section 331 routed in the first region HA11 is denoted as R1, and the electrical resistance value of the heating section 331 routed in the second region HA12 is denoted as R2, the electrostatic chuck 10 satisfies the condition (|R1-R2|) / R2<0.15.SELECTED DRAWING: Figure 8

Description

[Technical Field]

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

[0002] For example, semiconductor manufacturing equipment such as etching equipment is provided with an electrostatic chuck 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, attracting and holding the substrate placed on the dielectric substrate.

[0003] During substrate processing, it is necessary to make the temperature distribution within the surface of the substrate as uniform as possible. In order to enable the temperature distribution within the surface of the substrate to be adjusted with high precision, electrostatic chucks equipped with heaters have been developed in recent years and are already in practical use. The heater may be provided inside the dielectric substrate, as described in Patent Document 1 below, for example, or may be provided outside the dielectric substrate as a unit. In either configuration, the heater has a heat-generating portion that is a conductor routed in a linear fashion. In many cases, the heat-generating portion is not provided in the entire heater, but is routed individually in each of multiple regions. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-120910 Summary of the Invention [Problem to be solved by the invention]

[0005] Among the multiple regions, there may be a pair of regions that differ from each other in the area of ​​the portion in which the heat generating portion can be routed. If the heat generating portion is routed in each of such a pair of regions so that the line width and spacing of each portion in a top view are uniform, there is a possibility that the difference in electrical resistance between the heat generating portion in one region and the heat generating portion in the other region will be large.

[0006] When the electrical resistance values ​​vary greatly from one heat-generating part to another, as described above, it may become difficult to standardize the specifications of the power supplies connected to each heat-generating part, which may result in a problem in that the circuit configuration for temperature control becomes complicated.

[0007] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an electrostatic chuck that can simplify the circuit configuration for temperature adjustment control. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides an electrostatic chuck that includes a dielectric substrate having a mounting surface on which an object to be attracted is mounted, and a heater that heats the dielectric substrate. The heater has a heat-generating portion that is a linear conductor and generates heat when power is supplied from an external source. When viewed perpendicularly to the mounting surface, the heat-generating portion is individually routed in each of a plurality of regions. The plurality of regions includes a first region and a second region. This electrostatic chuck satisfies the condition (|R1-R2|) / R2<0.15, where R1 is the electrical resistance of the heat-generating portion routed in the first region and R2 is the electrical resistance of the heat-generating portion routed in the second region.

[0009] In an electrostatic chuck having such a configuration, the electrical resistance values ​​of a pair of heating elements routed in different regions are approximately equal to each other, which makes it possible to simplify the circuit configuration for temperature control, for example, by standardizing the specifications of the power supplies connected to the respective heating elements. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an electrostatic chuck that can simplify the circuit configuration for temperature control. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view schematically showing the configuration of an electrostatic chuck according to a first embodiment. [Figure 2] FIG. 2 is an exploded view schematically illustrating the configuration of the heater unit. [Figure 3] 10A and 10B are diagrams illustrating an example of the arrangement of sub-heater layers in a heater unit. [Figure 4] FIG. 1 is a diagram showing the configuration of one sub-heater layer. [Figure 5] 10A and 10B are diagrams illustrating an example 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. 10 is a diagram for explaining the role of a bypass layer, etc. [Figure 8] FIG. 3 is a diagram for explaining the configuration of a heat generating portion. [Figure 9] FIG. 3 is a diagram for explaining the configuration of a heat generating portion. [Figure 10] FIG. 10 is a cross-sectional view schematically showing the configuration of an electrostatic chuck according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

[0013] A first embodiment will be described. An electrostatic chuck 10 according to this embodiment is configured to electrostatically attract and hold a substrate W to be processed inside a semiconductor manufacturing apparatus (not shown), such as an etching apparatus. The object to be attracted, that is, the substrate W, is, for example, a silicon wafer. The electrostatic chuck 10 may also be used in apparatuses other than semiconductor manufacturing apparatuses.

[0014] 1 is a schematic cross-sectional view showing 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 also 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 placed. Also, a lower surface 120 of the dielectric substrate 100 in FIG. 1 is a "bonding 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 also 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 disposed parallel to the surface 110. In addition to tungsten, the adsorption electrode 130 may be made of molybdenum, platinum, palladium, or the like. When a voltage is applied to the adsorption electrode 130 from the outside, an electrostatic force is generated between the surface 110 and the substrate W, thereby adsorbing and holding the substrate W. Two adsorption electrodes 130 may be provided as so-called "bipolar" electrodes, or only one may be provided as so-called "monopolar" electrode.

[0018] A power supply terminal 132 is embedded in the surface 120 of the dielectric substrate 100. The power supply terminal 132 is a terminal for receiving a voltage to be applied to the chucking electrode 130 from the outside. The power supply terminal 132 has a circular shape when viewed from above. The power supply terminal 132 and the chucking electrode 130 are electrically connected by a via 131. The via 131 is a long, narrow hole filled with a conductor. One end of a bus bar 13, which is a rod-shaped conductive member, is connected to the power supply terminal 132. A voltage is applied to the chucking electrode 130 from the outside via the bus bar 13. The bus bar 13 is led out to the outside through a through hole 306 formed in the heater unit 300 and a through hole 240 formed in the base plate. Note that the configuration of the electric path for applying a voltage to the chucking electrode 130 may be different from that described above.

[0019] As shown in Fig. 1, a space SP is formed between the dielectric substrate 100 and the substrate W. When processing such as etching is performed in the semiconductor manufacturing equipment, helium gas for temperature adjustment is supplied to the space SP from the outside through gas holes 114. By providing helium gas between the dielectric substrate 100 and the substrate W, the thermal resistance between them is adjusted, thereby maintaining the temperature of the substrate W at an appropriate temperature. Note that the temperature adjustment gas supplied to the space SP may be a type of gas other than helium.

[0020] A seal ring 111 and dots 112 are provided on a surface 110 that is a mounting surface, and the space SP is formed around these.

[0021] 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 multiple 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.

[0022] 1, the portion marked with the reference numeral "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 portion of the surface 110 to the position of the bottom surface 116.

[0023] The dots 112 are circular protrusions that protrude 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 comes into contact with the substrate W. By providing a plurality of such dots 112, bending of the substrate W is suppressed.

[0024] Gas holes 114 are formed in the dielectric substrate 100. The gas holes 114 are holes for supplying helium gas to the space SP, and are circular through-holes formed to extend perpendicularly to the surface 110. A plurality of gas holes 114 are formed, but only one of them is shown in FIG. 1. Helium gas supplied from the outside passes through gas hole 214 formed in the base plate 200 and through-hole 305 formed in the heater unit 300, and is then supplied to the space SP through each gas hole 114.

[0025] A porous body made of, for example, alumina may be disposed inside the gas hole 114. With this configuration, it is possible to prevent dielectric breakdown from occurring in the path through the gas hole 114 while ensuring the flow of gas through the gas hole 114.

[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 260 for flowing a coolant is formed inside the base plate 200. When a process such as etching is performed in the semiconductor manufacturing equipment, a coolant is supplied to the coolant flow path 260 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. The coolant is supplied to and discharged from the coolant flow path 260 through an opening (not shown) formed in a surface 220 of the base plate 200 opposite to the surface 210.

[0028] A through-hole 240 is formed in the base plate 200 in a portion that overlaps with the power supply terminal 132 in a top view. The through-hole 240 is a circular through-hole that is formed to extend perpendicularly from the surface 210 toward the surface 220. As described above, the bus bar 13 for applying a voltage to the chucking electrode 130 is disposed inside the through-hole 240. A circular opening that is the upper end of the through-hole 240 is formed in the surface 210 of the base plate 200 that faces the dielectric substrate 100.

[0029] Gas holes 214 are formed in the base plate 200 in portions that overlap with the gas holes 114 in a top view. The gas holes 214 are circular through-holes that are formed to extend perpendicularly from the surface 210 toward the surface 220. As described above, the gas holes 214 form part of a path for supplying helium gas to the space SP. A plurality of gas holes 214 are formed in addition to the gas holes 114. A plurality of circular openings that are the upper ends of the gas holes 214 are formed in the surface 210 of the base plate 200 that faces the dielectric substrate 100.

[0030] A through hole 230 is formed in the base plate 200. The through hole 230 is a circular through hole formed to extend perpendicularly from the surface 210 toward the surface 220. The through hole 230 is a through hole for accommodating a power supply terminal 390 provided in the heater unit 300 described below and a power supply member connected thereto. A plurality of through holes 230 are formed, but only one of them is shown in FIG. 1 .

[0031] 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 an insulating film, the dielectric strength of the base plate 200 can be increased.

[0032] The heater unit 300 generates heat upon receiving an external power supply 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 adjusted individually. By adjusting the amount of heat generated by each part individually, the in-plane temperature distribution of the substrate W during processing can be made closer to uniform.

[0033] 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 are disposed inside each of the bonding layers to increase thermal conductivity. For example, particles containing alumina as a main component can be used as the filler.

[0034] A through hole 306 is formed in the heater unit 300 at a portion that overlaps with the power supply terminal 132 in a top view. The through hole 306 is a circular through hole that is formed to extend in a direction perpendicular to the surface 210. As described above, the bus bar 13 for applying a voltage to the chucking electrode 130 is disposed inside the through hole 306.

[0035] In the heater unit 300, a through hole 305 is formed in a portion that overlaps with the gas hole 114 in a top view. The through hole 305 is a circular through hole formed to extend in a direction perpendicular to the surface 210. As described above, the through hole 305 forms part of a path for supplying helium gas to the space SP. A plurality of through holes 305 are formed, along with the gas holes 114 and 214.

[0036] The electrostatic chuck 10 is formed with a plurality of lift pin holes for passing lift pins provided in a semiconductor manufacturing apparatus, but these are not shown in Fig. 1. The lift pin holes are circular through-holes formed to vertically penetrate the entire electrostatic chuck 10 including the heater unit 300, similar to the gas holes 114, the through-holes 305, and the gas holes 214. A surface 210 of the base plate 200 facing the dielectric substrate 100 is formed with a plurality of circular openings that are the upper ends of the lift pin holes.

[0037] The specific configuration of the heater unit 300 will be described. FIG. 2 shows a schematic exploded view of the configuration of the heater unit 300. 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 terminal 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 in FIG. 2, but the arrangement order of these layers may be different from that of this embodiment.

[0038] 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 that is bonded to the dielectric substrate 100 via a bonding layer 410, and the support plate 310B is a portion that is bonded to the base plate 200 via a bonding layer 420.

[0039] The pair of support plates 310A, 310B are members for reinforcing the entire heater unit 300 by sandwiching the entire sub-heater layer 330, main heater layer 350, bypass layer 370, etc. between them. In this embodiment, both support plates 310A, 310B are made of metal, but they may be made of other materials (e.g., insulating materials). Note that each of the members constituting the heater unit 300, such as the support plate 310, has a plurality of through holes formed therein corresponding to the previously described through holes 305 and 306, etc., but these are not shown in FIG. 2.

[0040] The insulating layer 320 is provided between the support plate 310A and the sub-heater layer 330 to electrically insulate them from each other. The insulating layer 320 also serves to physically bond them to each other. In this embodiment, the insulating layer 320 is a polyimide film, but it may contain components other than polyimide or may be made of a material other than polyimide. If the support plate 310A is made of an insulating material, the insulating layer 320 can be eliminated.

[0041] The sub-heater layer 330 generates heat when power is supplied from an external source. In Figure 2, the sub-heater layer 330 is depicted as a single disk, but in reality, the sub-heater layer 330 is divided into multiple regions, and each region can be individually heated. The specific configuration of the sub-heater layer 330 will be described later.

[0042] The insulating layer 340 is provided between the sub-heater layer 330 and the main heater layer 350 to electrically insulate them from each other. The insulating layer 340 also serves to physically bond them to each other. In this embodiment, the insulating layer 340 is a polyimide film, but it may contain components other than polyimide or may be made of a material other than polyimide.

[0043] The main heater layer 350, like the sub-heater layer 330 described above, generates heat when power is supplied from an external source. In Figure 2, the main heater layer 350 is depicted as a single disk, but in reality, the main heater layer 350 is divided into multiple regions, and each region can be individually heated. The specific configuration of the main heater layer 350 will be described later.

[0044] The main heater layer 350 generates a larger amount of heat per unit area than the sub-heater layer 330 described above. The main heater layer 350 is intended to raise 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 more uniform. In this way, in this embodiment, two heater layers are provided separately, each with its own role.

[0045] The insulating layer 360 is provided between the main heater layer 350 and the bypass layer 370 to electrically insulate them from each other. The insulating layer 360 also serves to physically bond them to each other. 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.

[0046] The bypass layer 370 is a layer for electrically connecting a power supply terminal 390 (described later) to the sub-heater layer 330 and the main heater layer 350. In FIG. 2, the bypass layer 370 is schematically depicted as a single disk, but in reality, the bypass layer 370 is divided into multiple 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 terminal 390, etc. A portion of each of the divided bypass layers 370 is electrically connected to the sub-heater layer 330 or the main heater layer 350.

[0047] The insulating layer 380 is provided between the bypass layer 370 and the support plate 310B to electrically insulate them from each other. The insulating layer 380 also serves to physically bond them to each other. In this embodiment, the insulating layer 380 is a polyimide film, but it may contain components other than polyimide or may be made of a material other than polyimide. If the support plate 310B is made of an insulating material, the insulating layer 380 may be eliminated.

[0048] 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.

[0049] The power supply terminal 390 is a part that receives, from the outside, the power required to generate heat in the sub-heater layer 330 and the like. In this embodiment, the power supply terminal 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 terminals 390 are provided, corresponding to the number of bypass layers 370, but only two of them are shown in FIG. 2. As described above, the base plate 200 has through holes 230 formed at positions corresponding to the power supply terminals 390, and the power supply terminals 390 are inserted through the through holes 230.

[0050] The structure of the sub-heater layer 330 will now be described. As mentioned above, the sub-heater layer 330 is divided into multiple regions, and each region can generate heat independently. Figure 3 shows an example of how the sub-heater layer 330 is divided, viewed from above. In this example, the sub-heater layer 330 is divided into a total of 32 regions HA.

[0051] 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 32 heat generating portions 331 are provided.

[0052] 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 throughout almost the entire area. The heat generating portion 331 is a portion that generates heat when power is supplied from an external source.

[0053] 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 entire portion functions as one sub-heater layer 330. In other words, one sub-heater layer 330 is provided for each of the 32 regions HA.

[0054] 4 is a schematic view of the heat generating portion 331 and differs from the actual shape. The same applies to the positions of the pad portions 332 and 333.

[0055] 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 independently. 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.

[0056] The main heater layer 350 is configured as linear heat generating portions 351, which are individually routed in each region HB. That is, in this embodiment, a total of three heat generating portions 351 are provided.

[0057] 6 shows an example of heat generating portions 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. The heat generating portion 351 is a portion that generates heat when power is supplied from an external source. The number of heat generating portions 351 (3 in total) is fewer than the number of heat generating portions 331 (32 in total).

[0058] 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 entire portion functions as one main heater layer 350. In other words, one main heater layer 350 is provided for each of the three regions HB.

[0059] 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.

[0060] 7 is a schematic perspective view showing 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 will also be referred to as "region HA1" below. The other region HA will also be referred to as "region HA2" below. Note that the shapes of the heat generating portion 331 and other components shown in FIG. 7 are schematic and differ from the actual shapes.

[0061] As described above, the bypass layer 370 is divided into multiple parts. In FIG. 7, only three of the multiple divided bypass layers 370 are shown. Of the three divided bypass layers 370, the one marked with the reference numeral "371" in FIG. 7 is arranged in a position overlapping only one region HA in top view. In other words, each of the bypass layers 370 is individually arranged in a position directly below each region HA. The portion of the bypass layer 370 arranged in this manner will also be referred to as the "bypass layer 371" below.

[0062] 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."

[0063] In the sub-heater layer 330 arranged in the region HA1, the pad portion 332 at one end of the heat generating portion 331 is electrically connected to the bypass layer 371 located immediately below it. The pad portion 333 at the other end of the heat generating portion 331 is electrically connected to the bypass layer 372.

[0064] The same applies to 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.

[0065] The electrical connection of each of the above-described parts is realized, for example, by welding the upper and lower layers together. To make the configuration easier to understand, in Fig. 7, each welded part is schematically depicted as a linear rod-shaped member (the part indicated by the reference numeral 301). In the parts overlapping with each welded part in top view, openings are formed in each of the layers (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 these openings.

[0066] The sub-heater layer 330 and the bypass layer 370 may be electrically connected by welding as in this embodiment, but may also be electrically connected by other methods. For example, they may be electrically connected via a conductive member extending vertically. In either configuration, an electrical path indicated by reference numeral 301 in FIG. 7 is formed between the sub-heater layer 330 and the bypass layer 370. This electrical path will hereinafter also be referred to as "electrical path 301."

[0067] One end of a power supply terminal 390 is connected to each bypass layer 371 from below in FIG. 7. A voltage is individually applied to each of these power supply terminals 390 from an external DC power supply. Similarly, one end of a power supply terminal 390 is connected to the bypass layer 372 from below in FIG. 7. This power supply terminal 390 is grounded. The DC power supply and the ground portion shown in FIG. 7 are part of a temperature adjustment control circuit that is externally connected to the electrostatic chuck 10.

[0068] 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 DC power supplies 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.

[0069] It is also possible to supply power to the sub-heater layer 330 directly from the power supply terminal 390 without passing through the bypass layer 370. However, by using a configuration in which power is supplied via the bypass layer 370 as in this embodiment, it is possible to increase the degree of freedom in arranging the power supply terminals 390 and to consolidate the power supply terminals 390 that are grounded into one.

[0070] The supply of power to each main heater layer 350 is also achieved by the same configuration as above. The specific configuration is the same as that shown in Fig. 7, so its description and illustration will be omitted.

[0071] However, the multiple regions HA for routing the heat generating portion 331 do not all have the same outer shape, as shown in Fig. 3. The multiple regions HA include a pair of regions HA that are located at different positions and have different outer shapes.

[0072] Figure 8 illustrates, in top view, an example of a pair of regions HA that differ from each other in their outer shapes. The outer shape of the region HA shown in Figure 8(A) is smaller than the outer shape of the region HA shown in Figure 8(B). The region HA shown in Figure 8(A) will also be referred to as the "first region HA11" below. The region HA shown in Figure 8(B) will also be referred to as the "second region HA12" below.

[0073] Fig. 8 illustrates the heat generating parts 331 routed in each area HA. ​​Note that in Fig. 8, the route along which the heat generating parts 331 are routed is schematic and differs from the actual route.

[0074] In this embodiment, the line width of the heat generating portion 331 routed in the first region HA11 having a small outer shape is narrower than the line width of the heat generating portion 331 routed in the second region HA12 having a large outer shape. As a result, the electrical resistance value of the heat generating portion 331 in the first region HA11 is approximately equal to the electrical resistance value of the heat generating portion 331 in the second region HA12.

[0075] Here, when the electrical resistance value (unit: Ω) of the heat generating portion 331 routed in the first region HA11 is R1 and the electrical resistance value (unit: Ω) of the heat generating portion 331 routed in the second region HA12 is R2, the electrostatic chuck 10 of this embodiment satisfies the condition (|R1-R2|) / R2<0.15.

[0076] In other words, in this embodiment, the line width of each of the heat generating portions 331 in the first region HA11 and the second region HA12 is adjusted so as to satisfy the condition (|R1-R2|) / R2<0.15.

[0077] If the above adjustments were not made and the line widths and spacings of the heat generating elements 331 were the same, R1 would be smaller than R2, and the heater unit 300 would not satisfy the above conditions. That is, the electrical resistance values ​​would vary greatly among the heat generating elements 331. In such a configuration, it would be difficult to standardize the specifications of the DC power supplies connected to the heat generating elements 331, which could lead to problems such as a complicated circuit configuration for temperature regulation control.

[0078] Therefore, in this embodiment, as described above, the electrical resistance values ​​of the heat generating parts 331 routed in each of the first area HA11 and the second area HA12 are adjusted to be close to each other so as to satisfy the condition (|R1-R2|) / R2<0.15. This makes it possible to standardize the specifications of the DC power supplies connected to each heat generating part 331, and to simplify the circuit configuration for temperature adjustment control.

[0079] The above condition (|R1-R2|) / R2<0.15 specifies that the absolute value of the difference between R1 and R2 must be less than 15% of R2. Experiments conducted by the present inventors have revealed that as long as R1 and R2 are close enough to each other that the absolute value of the difference is less than 15% of R2, there is no problem even if the specifications of the DC power supplies connected to the respective heat generating parts 331 are standardized.

[0080] The above-described adjustment of the electrical resistance value of the heat generating portion 331 may also be necessary for a pair of regions HA having the same outer shape.

[0081] 9A and 9B illustrate examples of a pair of regions HA having the same outer shape as each other, as viewed from above. The region HA shown in Fig. 9A is hereinafter also referred to as a "first region HA21." The region HA shown in Fig. 9B is hereinafter also referred to as a "second region HA22."

[0082] 9(A), a circular region D1 indicated by a dotted line represents a region of the first region HA21 where the heat generating portion 331 cannot be routed. Examples of such a region include regions that overlap with the through holes 305 and 306 shown in Fig. 1 in top view. The second region HA22 in Fig. 9(B) does not have the region D1 described above, and the heat generating portion 331 can be routed throughout the entire second region HA22.

[0083] In this way, the first region HA21 and the second region HA22 differ from each other in the area of ​​the portion in which the heat generating portion 331 can be routed. The area of ​​the portion in the first region HA21 in which the heat generating portion 331 can be routed is smaller (by the area of ​​region D1) than the area of ​​the portion in the second region HA22 in which the heat generating portion 331 can be routed.

[0084] In the first region HA21, the heat generating portion 331 needs to be routed so as to bypass the region D1. For this reason, the path length of the heat generating portion 331 in the first region HA21 is longer than the path length of the heat generating portion 331 in the second region HA22. Therefore, if the line widths of the heat generating portions 331 are equal to each other, the electrical resistance value R1 of the heat generating portion 331 routed in the first region HA21 will be greater than the electrical resistance value R2 of the heat generating portion 331 routed in the second region HA22. As a result, there is a possibility that the condition (|R1-R2|) / R2<0.15 will not be satisfied.

[0085] 9, the line width of the heat generating portion 331 routed in the first region HA21 is made wider than the line width of the heat generating portion 331 routed in the second region HA22 having the larger area. As a result, R1 and R2 are approximately equal to each other, and the condition (|R1-R2|) / R2<0.15 is satisfied.

[0086] At least two regions HA are required in which the electrical resistance values ​​of the heat generating portion 331 are approximately equal to each other, but it is preferable to have as many such regions HA as possible. For example, among the regions HA shown in FIG. 3, it is preferable to configure the heat generating portion 331 so that the electrical resistance values ​​of the heat generating portion 331 are approximately equal to each other across all of the multiple regions HA arranged in a circumferential direction. In other words, it is preferable that there is a group of multiple regions HA arranged in a circumferential direction that satisfies the condition (|R1-R2|) / R2<0.15, regardless of how the above-mentioned "first region" and "second region" are selected. This configuration makes it possible to easily uniform the distribution of heat generation amounts in each region in the circumferential direction.

[0087] In the above, the "plurality of regions HA arranged to be aligned in the circumferential direction" may be arranged to be aligned along the entire circumferential direction (i.e., along the entire circumference), or may be arranged to be aligned only in a predetermined range along the circumferential direction. Also, the "plurality of regions HA arranged to be aligned in the circumferential direction" may be arranged to be aligned only at a specific position along the radial direction (i.e., only one circumference), or may be arranged to be aligned along the entire radial direction (i.e., over multiple circumferences).

[0088] It is preferable that the plurality of regions HA in which the electrical resistance values ​​of the heat generating portion 331 are approximately equal to one another be lined up in the circumferential direction all around the heater unit 300, particularly at the outermost position.

[0089] The electrical resistance value of the heat generating portion 331 routed in each region HA may be adjusted by the line width of the heat generating portion 331 as in this embodiment, but instead of or in addition to adjustment by the line width, it may also be adjusted by the path length of the heat generating portion 331.

[0090] The same adjustment of the electrical resistance value as above may be performed on the heat generating portion 351 in each region HB.

[0091] The second embodiment will be described below. Differences from the first embodiment will be mainly described below, and descriptions of commonalities with the first embodiment will be omitted as appropriate.

[0092] 10 is a schematic cross-sectional view showing the configuration of an electrostatic chuck 10 according to this embodiment. As shown in the figure, in this embodiment, a heater unit 300 is not provided between a dielectric substrate 100 and a base plate 200. The dielectric substrate 100 and the base plate 200 are directly bonded to each other via a bonding layer 400. The bonding layer 400 is similar to the bonding layer 410 of the first embodiment and is a layer formed by curing a silicone adhesive.

[0093] In this embodiment, a heater layer 300A is embedded inside the dielectric substrate 100. The heater layer 300A generates heat when supplied with power from an external source and heats the dielectric substrate 100. Like the attraction electrode 130, the heater layer 300A is a thin, flat layer made of a metal material (i.e., a conductor) such as tungsten, and is disposed parallel to the surface 110. In top view, the heater layer 300A has a heat generating portion that is routed linearly. The heat generating portion is routed, for example, along a path generally similar to that of the heat generating portion 331 of the first embodiment.

[0094] A power supply terminal 142 is embedded in the surface 120 of the dielectric substrate 100. The power supply terminal 142 is a terminal for receiving power from the outside to be supplied to the heat generating portion of the heater layer 300A. The power supply terminal 142 has a circular shape when viewed from above. The power supply terminal 142 and the heat generating portion of the heater layer 300A are electrically connected by vias 141. The vias 141 are elongated holes filled with a conductor. One end of a bus bar 14, which is a rod-shaped conductive member, is connected to the power supply terminal 142. Power is supplied from the outside to the heat generating portion of the heater layer 300A via the bus bar 14. The bus bar 14 is drawn out to the outside through a through hole 250 formed in the base plate. The configuration of the electric circuit for supplying power to the heat generating portion of the heater layer 300A may be different from that described above.

[0095] The heat generating portion of the heater layer 300A needs to be routed inside the dielectric substrate 100 along a path that avoids the gas holes 114 and the vias 131 when viewed from above.

[0096] The heater layer 300A provided inside the dielectric substrate 100 may be a single layer or multiple layers. For example, the main heater layer 350, sub-heater layer 330, and bypass layer 370 similar to those in the first embodiment may each be provided inside the dielectric substrate 100. In this case, the electrical path 301 connecting between the sub-heater layer 330 and the bypass layer 370 may be formed, for example, as a hole (via) filled with a conductor, rather than by welding. The same applies to the electrical path connecting between the main heater layer 350 and the bypass layer 370.

[0097] The above configuration can also employ the same configuration as in the first embodiment. That is, the line width of each heat generating portion may be adjusted so that the electrical resistance values ​​of the multiple heat generating portions of the heater layer 300A are approximately equal in each region to the extent that the condition (|R1-R2|) / R2<0.15 is satisfied. This can achieve the same effects as those described in the first embodiment.

[0098] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise. [Explanation of symbols]

[0099] 10: Electrostatic chuck 100: Dielectric substrate 110: Face 300: Heater unit 331, 351: Heat generating part HA,HB:Area HA11,HA21: 1st area HA12,HA22:Second area W: Substrate

Claims

1. a dielectric substrate having a mounting surface on which an object to be attracted is placed; a heater for heating the dielectric substrate, The heater has a heat generating portion which is a conductor drawn in a linear shape and generates heat when supplied with electric power from an external source, When viewed from a direction perpendicular to the placement surface, The heat generating portion is It is routed individually in each of the multiple areas, the plurality of regions include a first region and a second region, The electrical resistance value of the heat generating portion routed in the first region is R1, When the electrical resistance value of the heat generating portion routed in the second region is R2, (|R1-R2|) / R2<0.15 An electrostatic chuck characterized by satisfying the above conditions.

2. A plurality of the regions arranged in a circumferential direction, 2. The electrostatic chuck according to claim 1, wherein a group of said regions exists that satisfies said condition regardless of how said first region and said second region are selected.

3. 2. The electrostatic chuck according to claim 1, wherein the first region and the second region are different from each other in terms of the area of ​​the portion through which the heat generating portion can be routed.

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