Electrostatic chuck

Abstract

Provided is an electrostatic chuck capable of suppressing an influence on a state of plasma. This electrostatic chuck 10 includes a dielectric substrate 100, and a heater unit 300 for heating the dielectric substrate 100. In a top view, the heater unit 300 includes: a heat generation unit 331 that is a conductor routed linearly on the inner side of a first region HA1; a heat transfer unit 335 that is a conductor disposed so as to occupy the entirety of a second region HA2 that is adjacent to the first region HA1 and has an area larger than the first region HA1; and a connection part 336 that electrically connects the heat generation unit 331 and the heat transfer unit 335.

Description

Electrostatic chuck

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

[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] When processing a substrate 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. To enable highly accurate temperature adjustment, 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, or may be provided as a unit between the dielectric substrate and a base plate, as described in, for example, Patent Document 1 listed below.

[0004] Japanese Patent Application Laid-Open No. 2021-197485

[0005] The heater has a heat-generating portion that is a linear conductor. When power is supplied from an external source and a current flows through the heat-generating portion, Joule heat is generated in the heat-generating portion. To enable individual temperature adjustment of each portion of the dielectric substrate, the heat-generating portion of the heater is individually routed in each of the multiple regions.

[0006] Among the multiple regions, there may be regions where it is not necessary to place a heat-generating portion. However, if regions with and without heat-generating portions are mixed, the thermal resistance between the substrate (e.g., silicon wafer) and the base plate will not be uniform throughout, and the thermal resistance will differ from region to region. One possible measure to make the thermal resistance uniform is to place a dummy conductor layer in place of a heat-generating portion in regions where it is not necessary to place a heat-generating portion.

[0007] However, because the dummy conductor layer is a so-called "floating conductor," its potential fluctuates due to its surroundings. On the other hand, because the heating element is connected to the power supply via a filter circuit that suppresses potential fluctuations, its potential is not affected by its surroundings. Therefore, during substrate processing, the potential difference between the dummy conductor layer and the heating element becomes large, which may adversely affect the state of the plasma generated above the substrate.

[0008] 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 suppress the influence on the state of plasma.

[0009] In order to achieve the above object, 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 for heating the dielectric substrate. When viewed perpendicularly to the mounting surface, the heater has a heat generating portion which is a conductor linearly routed inside a first region, a heat transfer portion which is a conductor arranged so as to occupy the entire second region adjacent to the first region and having an area larger than that of the first region, and a connection portion which electrically connects the heat generating portion and the heat transfer portion.

[0010] In an electrostatic chuck having such a configuration, by arranging a heat generating portion in the first region and a heat transfer portion in the second region where a heat generating portion is not required, the thermal resistances of the first region and the second region can be made approximately the same. Furthermore, by electrically connecting the heat generating portion and the heat transfer portion via a connecting portion, the heat transfer portion can be prevented from becoming a so-called "floating conductor." Since the electric potentials of the heat generating portion and the heat transfer portion are approximately the same, the state of the plasma generated above the substrate is hardly affected by the potential difference between them.

[0011] According to the present invention, it is possible to provide an electrostatic chuck that can suppress the influence on the plasma state.

[0012] FIG. 1 is a cross-sectional view schematically showing the configuration of an electrostatic chuck according to a first embodiment; FIG. 2 is an exploded view schematically showing the configuration of a heater unit; FIG. 3 is a view showing an example of the arrangement of a main heater layer in a heater unit; FIG. 4 is a view showing the configuration of one main heater layer; FIG. 5 is a view showing an example of the arrangement of sub-heater layers and the like in a heater unit; FIG. 6 is a view showing the configuration of one sub-heater layer and a heat transfer section located in the vicinity thereof; FIG. 7 is a view for explaining the role of a bypass layer and the like; FIG. 8 is a view showing the configuration of one sub-heater layer and a heat transfer section located in the vicinity thereof of an electrostatic chuck according to a modified example of the first embodiment; FIG. 9 is a view showing the configuration of one sub-heater layer and a heat transfer section located in the vicinity thereof of an electrostatic chuck according to a modified example of the second embodiment; FIG. 10 is a view showing the configuration of one sub-heater layer and a heat transfer section located in the vicinity thereof of an electrostatic chuck according to a modified example of the second embodiment;

[0013] 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.

[0014] 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 also be used in apparatuses other than semiconductor manufacturing apparatuses.

[0015] 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.

[0016] 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 taking into consideration the plasma resistance and other properties required of the dielectric substrate 100 in semiconductor manufacturing equipment.

[0017] 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 also be referred to as a "top view."

[0018] 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. The adsorption electrode 130 may be made of 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. Various known configurations can be employed as the configuration of the power supply path. Only one adsorption electrode 130 may be provided as a so-called "monopolar" electrode, as in this embodiment, or two may be provided as so-called "bipolar" electrodes.

[0019] 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 to the space SP from the outside 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, 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 the surface 110 that is the 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 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.

[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] 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. An upper surface 210 of the base plate 200 in FIG. 1 serves as a "bonded surface" that is bonded to the heater unit 300 via a bonding layer 420.

[0025] 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 equipment, a coolant is supplied from the outside to the coolant flow path 250, 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.

[0026] 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.

[0027] 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 heat generation amount of each heat generating part 331, etc. can be individually adjusted. By individually adjusting the heat generation amount of each part, it is possible to make the in-plane temperature distribution of the substrate W during processing more uniform.

[0028] The heater unit 300 is sandwiched between the dielectric substrate 100 and the base plate 200 and bonded to each. 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.

[0029] The specific configuration of the heater unit 300 will be described. Fig. 2 shows the configuration of the heater unit 300 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 part 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 top to bottom, but the arrangement order may be different from that of this embodiment.

[0030] The support plate 310 is a substantially disk-shaped member and is provided at each of the upper and lower ends of the heater unit 300 in FIG. 2. The support plate 310 provided at the upper end in FIG. 2 is also referred to as the "support plate 310A" below. The support plate 310 provided at the lower end in FIG. 2 is also referred to as the "support plate 310B" below. The 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.

[0031] 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. In this embodiment, both the support plates 310A, 310B are made of metal, but they may also be made of other materials (for example, insulating materials).

[0032] 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 may be omitted.

[0033] The sub-heater layer 330 generates heat when power is supplied from an external source. In Fig. 2, the sub-heater layer 330 is schematically 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.

[0034] 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 a component other than polyimide or may be made of a material other than polyimide.

[0035] The main heater layer 350, like the sub-heater layer 330 described above, generates heat when power is supplied from an external source. While the main heater layer 350 is depicted as a single disk in Fig. 2, in reality, the main heater layer 350 is divided into multiple regions, each of which can be individually heated. The specific configuration of the main heater layer 350 will be described later.

[0036] The main heater layer 350 has a larger heat generation amount than the sub-heater layer 330 described above. The main heater layer 350 is intended to 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 according to their respective roles. Alternatively, a configuration in which only one heater layer is provided may be used.

[0037] The insulating layer 360 is provided between the main heater layer 350 and the bypass layer 370 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.

[0038] The bypass layer 370 is a layer for electrically connecting the power supply unit 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 unit 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.

[0039] 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 omitted.

[0040] 2 are laminated together, the entire assembly is pressurized and heated, thereby bonding the entire assembly together via the insulating layer 320, which is a polyimide film, and forming an integrated unit.

[0041] The power supply unit 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 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, corresponding 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.

[0042] The structure of the main heater layer 350 will now be described. As described above, the main heater layer 350 is divided into multiple regions, and each region can generate heat independently. FIG. 3 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. FIG. 3 also shows boundaries B1 and B2 that separate adjacent regions HB.

[0043] Each divided main heater layer 350 is configured as a linear heat generating portion 351, which is routed individually inside each region HB. "Routed individually inside" a region HB means that the heat generating portion 351 does not extend across the boundary into an adjacent region HB. The heat generating portion 351 is a linear conductor that generates heat upon receiving power from the power supply portion 390. FIG. 4 shows an example of a heat generating portion 351 routed inside one region HB. Inside each region HB, one linear heat generating portion 351 is routed along a path that passes evenly throughout almost the entire range. Two or more heat generating portions 351 connected in parallel to each other may be routed.

[0044] Circular widened portions 352, 353 are formed on both ends of the heat generating portion 351. The widened portions 352, 353 are both part of the heat generating portion 351, and are portions where the line width of the heat generating portion 351 is locally enlarged. The widened portions 352, 353 are portions where the bypass layer 370 is electrically connected, for example, by welding. The widened portions 352, 353 may have a circular shape as in this embodiment, or may have a shape other than a circle.

[0045] The heat generating portion 351 including the widened portions 352 and 353 is 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. The respective main heater layers 350 can be simultaneously formed by etching a single metal foil, for example.

[0046] 4 is a schematic view and differs from the actual shape of the main heater layer 350. For example, there may be a main heater layer 350 in which the widened portion 352 is provided not at the end of the heat generating portion 351 but at a position midway along the heat generating portion 351.

[0047] The structure of the sub-heater layer 330 will now be described. Like the main heater layer 350, the sub-heater layer 330 is also divided into multiple regions, allowing each region to generate heat independently. Each region in which the sub-heater layer 330 is disposed is hereinafter also referred to as a "first region HA1." FIG. 5 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 16 first regions HA1.

[0048] Among the boundaries indicated by dotted lines in Fig. 5, the boundary marked with the symbol "B1" completely overlaps with the boundary B1 shown in Fig. 3 in top view. Also, the boundary marked with the symbol "B2" completely overlaps with the boundary B2 shown in Fig. 3 in top view.

[0049] 5, the circular area inside the boundary marked with the symbol "B2" is an area where the heat generating portion 331, which will be described below, is not disposed. This area will also be referred to as the "second area HA2" below. The second area HA2 is an area adjacent to the first area HA1 and has a larger area than either of the first areas HA1.

[0050] In this way, the heater unit 300 of this embodiment adjusts the in-plane temperature distribution by arranging the sub-heater layer 330 only in each first region HA1 near the outer periphery, and not in the second region HA2 in the center.

[0051] The plurality of first regions HA1 are arranged in a ring shape when viewed from above. In this embodiment, the plurality of first regions HA1 are arranged in a ring shape on both the inner and outer circumferential sides. That is, the plurality of first regions HA1 are arranged in a ring shape and in two rows. Alternatively, the plurality of first regions HA1 may be arranged in a ring shape and in a single row. The second region HA2 is an area adjacent to the plurality of ring-shaped first regions HA1 from the inner circumferential side.

[0052] Each divided sub-heater layer 330 is configured as a linear heat generating portion 331, which is individually routed inside each first region HA1. Being individually routed "inside" the first region HA1 means that the heat generating portion 331 does not extend across the boundary into an adjacent first region HA1. Like the heat generating portion 351, the heat generating portion 331 is a linear conductor that generates heat upon receiving power from the power supply portion 390. FIG. 6 shows an example of a heat generating portion 331 routed inside one first region HA1. Inside each first region HA1, one linear heat generating portion 331 is routed along a path that uniformly passes through almost the entire area. Two or more heat generating portions 331 connected in parallel may be routed.

[0053] Circular widened portions 332, 333 are formed on both ends of the heat generating portion 331. The widened portions 332, 333 are each part of the heat generating portion 331, and are portions where the line width of the heat generating portion 331 is locally expanded. The widened portions 332, 333 are portions where the bypass layer 370 is electrically connected, for example, by welding. The widened portions 332, 333 may have a circular shape as in this embodiment, or may have a shape other than a circle.

[0054] The heat generating portion 331 including the widened portions 332 and 333 is 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 16 first regions HA1.

[0055] 6 is a schematic view and differs from the actual shape of the sub-heater layer 330. For example, the sub-heater layer 330 may have the widened portion 332 or the like not at the end of the heat generating portion 331 but at a position midway along the heat generating portion 331.

[0056] As shown in Fig. 6, a heat transfer portion 335, which is a conductor, is disposed in a second region HA2 adjacent to the first region HA1. For convenience of illustration, Fig. 6 depicts a small gap between the dotted line defining the second region HA2 and the heat transfer portion 335, but in reality, no such gap exists. The same applies to Fig. 8 and other figures used in the following description.

[0057] The heat transfer portion 335 is disposed at the same height as the sub-heater layer 330, occupying the entire second region HA2. The thickness of the heat transfer portion 335 is equal to the thickness of the sub-heater layer 330. The heat transfer portion 335 is formed simultaneously with each sub-heater layer 330, for example, by etching a single metal foil. In this embodiment, the shape of the heat transfer portion 335 when viewed from above is circular. For example, an opening may be formed through the heat transfer portion 335 to avoid a lift pin hole (not shown). In this case, the portion excluding the opening corresponds to the "second region HA2." In either case, the heat transfer portion 335 is disposed to occupy the entire second region HA2.

[0058] By arranging the heat transfer part 335 so as to occupy the entire second area HA2, which is an area where the heat generating part 331 does not need to be arranged, the thermal resistance between the substrate W and the base plate 200 can be made uniform. That is, the thermal resistance in the second area HA2 can be made approximately the same as the thermal resistance in each first area HA1. This makes it possible to suppress variations in the in-plane temperature distribution of the substrate W during processing. Note that the second area HA2 may be the entire area where the heat generating part 331 does not need to be arranged, or may be a part of it.

[0059] 7 is a schematic perspective view showing the configuration of two first regions HA1, two sub-heater layers 330 arranged therein, and a bypass layer 370 connected to the sub-heater layers 330. Hereinafter, one of the two first regions HA1 shown in FIG. 7 will also be referred to as the "first region HA11." Hereinafter, the other first region HA1 will also be referred to as the "first region HA12." Note that the shapes of the heat generating portions 331 and the like shown in FIG. 7 are schematic and differ from the actual shapes.

[0060] 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 designated by the reference numeral "371" in FIG. 7 is arranged in a position overlapping only one first region HA1 in top view. In other words, each of the three divided bypass layers 370 is individually arranged in a position directly below each first region HA1. The portions of the bypass layer 370 arranged in this manner will also be referred to as "bypass layers 371" below.

[0061] 7 is disposed in a position overlapping both the first region HA11 and the first region HA12 in top view. The portion of the bypass layer 370 disposed in this manner is hereinafter also referred to as the "bypass layer 372."

[0062] In the sub-heater layer 330 arranged in the first area HA11, the widened portion 332 at one end of the heat generating portion 331 is electrically connected to the bypass layer 371 located immediately below it. The widened portion 333 at the other end of the heat generating portion 331 is electrically connected to the bypass layer 372.

[0063] The same applies to the sub-heater layer 330 arranged in the first region HA12, where the widened portion 332 at one end of the heat generating portion 331 is electrically connected to the bypass layer 371 located immediately below it. The widened portion 333 at the other end of the heat generating portion 331 is electrically connected to the bypass layer 372.

[0064] In this embodiment, the electrical connections between the above-described components are achieved by welding the upper and lower layers together. To facilitate understanding of the configuration, Fig. 7 shows each welded portion as a straight, rod-like member (the portion designated by the reference numeral 301), but the actual shape of the welded portion differs from this. In addition, in the portions overlapping with each welded portion 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 directly overlap through these openings.

[0065] One end of a power supply unit 390 is connected to each bypass layer 371 from below in Fig. 7. A voltage is individually applied to each of these power supply units 390 from an external DC power supply via a filter circuit 500 (described later). 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.

[0066] As described above, in each of the sub-heater layers 330 (heat generating portions 331) provided in each first region HA1, the widened portions 332 are connected to individual DC power supplies via the bypass layer 371, and the widened portions 333 are 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 in each portion.

[0067] 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 via 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.

[0068] 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 description and illustration thereof will be omitted. The bypass layer 370 connected to the sub-heater layer 330 and the bypass layer 370 connected to the main heater layer 350 may be located at the same height position (the position of the bypass layer 370 shown in Fig. 2) as in this embodiment, or may be located at different height positions.

[0069] 7, a filter circuit 500 is provided between each power supply unit 390 and a DC power supply. The filter circuit 500 is a circuit for suppressing fluctuations in the potential of the sub-heater layer 330 and the like due to the influence of plasma, etc., and is also called an "RF filter." The provision of the filter circuit 500 suppresses fluctuations in the potential of the sub-heater layer 330 and the like during processing of the substrate W.

[0070] In a configuration in which the heat-generating unit 331 is not provided in some regions and the heat-transfer unit 335 is provided instead, as in this embodiment, the heat-transfer unit 335 is not connected to the filter circuit 500 or the DC power supply, and is not grounded, so that the heat-transfer unit 335 becomes a so-called "floating conductor." That is, the potential of the heat-transfer unit 335 fluctuates due to the influence of the surroundings. On the other hand, since the heat-generating unit 331 is connected to the DC power supply via the filter circuit 500 as described above, its potential is not influenced by the surroundings. Therefore, during processing of the substrate W, the potential difference between the heat-transfer unit 335 and the heat-generating unit 331 becomes large, which may adversely affect the state of the plasma generated above the substrate W.

[0071] Therefore, in the electrostatic chuck 10 according to this embodiment, some of the heat generating portions 331 are electrically connected to the heat transfer portions 335 so that the heat transfer portions 335 do not become floating conductors.

[0072] Figure 8 shows the heat generating portion 331 and its surrounding configuration, which are located in a different position from those shown in Figure 6. As shown in Figure 8, in this embodiment, the heat generating portion 331 and the heat transfer portion 335 are electrically connected via a connection portion 336. The connection portion 336 is formed simultaneously with the sub-heater layer 330 and the heat transfer portion 335 by, for example, etching a single metal foil. In this embodiment, the connection portion 336 is formed as a linear pattern connecting the heat generating portion 331 and the heat transfer portion 335.

[0073] The heat transfer part 335 is connected to the heat generating part 331 via the connection part 336, and is therefore also connected to the filter circuit 500 and the DC power supply. The effect of suppressing potential fluctuations by the filter circuit 500 applies not only to the heat generating part 331 but also to the heat transferring part 335, so the respective potentials of the heat generating part 331 and the heat transferring part 335 are substantially the same even during processing of the substrate W. This prevents the state of the plasma generated above the substrate W from being affected by the potential difference between them.

[0074] In the present embodiment, of the heat generating portions 331 inside each of the first areas HA1, only a single heat generating portion 331 (i.e., only the heat generating portion 331 shown in FIG. 8 ) is electrically connected to the heat transfer portion 335 via the connection portion 336. Instead of this configuration, a configuration may be adopted in which multiple or all heat generating portions 331 adjacent to the heat transfer portion 335 are electrically connected to the heat transfer portion 335 via the connection portion 336.

[0075] As described above, the heat generating portion 331, the heat transfer portion 335, and the connection portion 336 are simultaneously formed by etching a single metal foil, and are therefore made of the same material. This configuration makes it easy to form the entire heat generating portion 331, the heat transfer portion 335, and the connection portion 336.

[0076] In this embodiment, a plurality of first regions HA1 are arranged in a ring shape, and the heat transfer portion 335 is arranged at a position on the inner periphery of the ring-shaped first regions HA1. Alternatively, as shown in the modified example of FIG. 9, the heat transfer portion 335 may be arranged at a position on the outer periphery of the ring-shaped first regions HA1. In this case, the shape of the heat transfer portion 335 in top view may be, for example, an annular shape rather than a circular shape. Note that in the example of FIG. 9, the second region HA2 is adjacent to the first region HA1 and has a larger area than any of the first regions HA1.

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

[0078] That is, a heat generating portion 331 made of a linear conductor may be embedded inside the dielectric substrate 100 as a heater. In this case, the power supply portion 390 is provided on the surface 120 side of the dielectric substrate 100, and the bypass layer 370 connecting the power supply portion 390 and the heat generating portion 331, the heat transfer portion 335, and the connection portion 336 are also embedded inside the dielectric substrate 100 like the heat generating portion 331. The connection between the bypass layer 370 and the heat generating portion 331 may be made through elongated vias (holes) filled with a conductor, rather than by welding as in this embodiment. In this case, too, it is preferable that the heat generating portion 331, the heat transfer portion 335, and the connection portion 336 are made of the same material (for example, a metal material such as tungsten).

[0079] A 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.

[0080] Figure 10 illustrates the configuration of the sub-heater layer 330 and its vicinity in this embodiment from the same perspective as Figure 8. In this embodiment, the heat generating portion 331 and the heat transfer portion 335 are connected by two connectors (connections 336A and 336B) instead of one. Both connectors 336A and 336B are formed as linear patterns connecting the heat generating portion 331 and the heat transfer portion 335, and are connected to different positions on the heat generating portion 331. A portion of the heat generating portion 331 between connectors 336A and 336B is cut out. The heat generating portion 331 and the heat transfer portion 335 are also connected by connector 336C. ​​Connector 336C is a linear pattern formed inside the first region HA1 to connect the heat generating portion 331 and the heat transfer portion 335.

[0081] In this configuration, a portion of the current flowing through the heat generating portion 331 passes through the connection portion 336A, the heat transfer portion 335, and the connection portion 336B in this order, and then flows through the heat generating portion 331 again. The remaining portion of the current flowing through the heat generating portion 331 passes through the connection portion 336A, the connection portion 336C, and the connection portion 336B in this order, and then flows through the heat generating portion 331 again without passing through the heat transfer portion 335. In this manner, the connection portions 336A, 336B, and 336C of this embodiment are configured so that a portion of the current passing through the heat generating portion 331 also passes through the heat transfer portion 335. In the heat transfer portion 335, Joule heat is generated by the current passing therethrough, and the dielectric substrate 100 directly above it is heated.

[0082] The difference between the amount of heat generated in the first area HA1 and the amount of heat generated in the second area HA2 can be reduced by generating a small amount of heat also in the heat transfer section 335. Depending on the tendency of the in-plane temperature distribution during processing of the substrate W, such a configuration can also suppress variations in the in-plane temperature distribution.

[0083] If it is necessary to further increase the amount of heat generated in heat transfer portion 335, for example, a configuration in which connecting portion 336C is eliminated from the example in Fig. 10 can be used, as in the modified example shown in Fig. 11. In such a configuration, not only a portion but all of the current flowing through heat generating portion 331 passes through connecting portion 336A, heat transfer portion 335, and connecting portion 336B in this order, and then flows through heat generating portion 331 again. As a result, more Joule heat can be generated in heat transfer portion 335 than in the example in Fig. 10.

[0084] 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.

[0085] 10: Electrostatic chuck 100: Dielectric substrate 110: Surface 300: Heater unit 331: Heat generating portion 335: Heat transfer portion 336: Connection portion HA1: First region HA2: Second region

Claims

1. An electrostatic chuck comprising: a dielectric substrate having a mounting surface on which an object to be attracted is placed; and a heater for heating the dielectric substrate, wherein, when viewed from a direction perpendicular to the mounting surface, the heater has: a heat generating portion which is a conductor routed linearly inside a first region; a heat transfer portion which is a conductor arranged so as to occupy the entirety of a second region adjacent to the first region and having an area larger than that of the first region; and a connection portion which electrically connects the heat generating portion and the heat transfer portion.

2. An electrostatic chuck as described in claim 1, characterized in that, when viewed from a direction perpendicular to the mounting surface, a plurality of the first regions are arranged in a ring shape, and the second region is arranged at a position on the inner or outer periphery side of the plurality of first regions.

3. An electrostatic chuck as described in claim 2, characterized in that, of the heat generating portions located inside the plurality of first regions, only a single heat generating portion is electrically connected to the heat transfer portion via the connection portion.

4. The electrostatic chuck according to claim 1, wherein the connection portion is configured so that at least a portion of the current passing through the heat generating portion also passes through the heat conducting portion.

5. The electrostatic chuck according to claim 1, wherein the heat generating portion, the heat conducting portion, and the connecting portion are made of the same material.

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