Electrostatic chuck

Abstract

To provide an electrostatic chuck in which a heating portion routed in a linear shape does not damage surrounding members.SOLUTION: An electrostatic chuck 10 includes a dielectric substrate 100, and a heater unit 300 that heats the dielectric substrate 100. The heater unit 300 includes a heat generating portion 331 that is a conductor laid out in a linear shape and generates heat by receiving a supply of electric power from an external source. When viewed from above, the heat generating portion 331 includes a bent portion CV that is a portion whose extension direction is bent at an acute angle, and the radius of curvature of the ridgeline on the outer periphery of the bent portion CV is 0.1 mm or more.SELECTED DRAWING: Figure 7

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] During substrate processing, it is required to make the temperature distribution in the surface of the substrate as uniform as possible. In order to adjust the temperature distribution in the surface of the substrate with high accuracy, 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 as described in, for example, Patent Document 1 below, or may be provided outside the dielectric substrate as a unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-120910 A Summary of the Invention [Problem to be solved by the invention]

[0005] The heater has a heat generating part which is a conductor drawn in a linear shape. When external power is supplied to the heat generating part, Joule heat is generated in the heat generating part. The heat generating part is drawn along a complex path which is bent at many points so that the amount of heat generated in each part of the area directly under the substrate is as uniform as possible. For example, around a circular through hole, there may be some points where the heat generating part is bent at an acute angle.

[0006] The ridges on the outer periphery of the heat generating part, which are bent at an acute angle, have sharp tips. Therefore, there is a possibility that the sharp tips of the heat generating part may hit the surrounding materials and damage the materials. An example of the "surrounding materials" of the heat generating part is an insulating resin sheet that is arranged to sandwich the heat generating part. If the resin sheet is scratched, the dielectric strength voltage of the part may decrease.

[0007] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide an electrostatic chuck in which a heating portion routed in a linear shape does not damage surrounding members. [Means for solving the problem]

[0008] In order to solve the above problems, an electrostatic chuck according to the present invention includes a dielectric substrate having a mounting surface on which an object to be attracted is mounted, and a heater for heating the dielectric substrate. The heater has a heat generating portion which is a conductor laid out in a linear shape and generates heat when supplied with electric power from an external source. When viewed from a direction perpendicular to the mounting surface, the heat generating portion includes a bent portion which is a portion whose extension direction is bent at an acute angle, and the radius of curvature of the ridgeline on the outer periphery of the bent portion is 0.1 mm or more.

[0009] In an electrostatic chuck having such a configuration, the heat generating portion is formed such that the radius of curvature of the ridgeline on the outer periphery of the bent portion is 0.1 mm or more. In the bent portion, which is bent at an acute angle in the extending direction, the ridgeline on the outer periphery is not sharp and is an arc shape with a radius of curvature of 0.1 mm or more, so that the heat generating portion will not damage surrounding members. Effect of the Invention

[0010] According to the present invention, it is possible to provide an electrostatic chuck in which a heating portion routed in a linear shape does not damage surrounding members. [Brief description of the drawings]

[0011] [Figure 1]1 is a cross-sectional view illustrating a schematic configuration of an electrostatic chuck according to a first embodiment. [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] 10A and 10B are diagrams for explaining a specific shape of a bent portion of the heat generating portion. [Figure 8] FIG. 11 is a cross-sectional view illustrating a schematic configuration of an electrostatic chuck according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

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

[0014] 1 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 contain other materials. The purity, type, and additives of the ceramics in the dielectric substrate 100 can be appropriately set in consideration of the plasma resistance and other properties required of the dielectric substrate 100 in semiconductor manufacturing equipment.

[0016] 1 of the dielectric substrate 100 is a "mounting surface" on which the substrate W is mounted. Also, a lower surface 120 of the dielectric substrate 100 in FIG. 1 is a "bonded surface" that is bonded to the heater unit 300 via a bonding layer 410. The viewpoint when the electrostatic chuck 10 is viewed from the side of the surface 110 along a direction perpendicular to the surface 110 will hereinafter be referred to as a "top view".

[0017] An adsorption electrode 130 is embedded inside the dielectric substrate 100. The adsorption electrode 130 is a thin flat layer made of a metal material such as tungsten, and is arranged parallel to the surface 110. The material of the adsorption electrode 130 may be molybdenum, platinum, palladium, or the like, in addition to tungsten. When a voltage is applied to the adsorption electrode 130 from the outside via a power supply path (not shown), an electrostatic force is generated between the surface 110 and the substrate W, thereby adsorbing and holding the substrate W. As the configuration of the power supply path, various known configurations can be adopted. The adsorption electrode 130 may be provided as a so-called "monopolar" electrode as in this embodiment, or may be provided as two so-called "bipolar" electrodes.

[0018] As shown in Fig. 1, a space SP is formed between the dielectric substrate 100 and the substrate W. When a process such as film formation is performed in the semiconductor manufacturing apparatus, helium gas for temperature adjustment is supplied from the outside to the space SP through a gas hole (not shown). By providing helium gas between the dielectric substrate 100 and the substrate W, the thermal resistance between them is adjusted, and the temperature of the substrate W is thereby maintained at an appropriate temperature. The gas for temperature adjustment supplied to the space SP may be a type of gas other than helium.

[0019] A seal ring 111 and dots 112 are provided on a surface 110 serving as a mounting surface, and the above-mentioned space SP is formed around these.

[0020] The seal ring 111 is a wall that divides the space SP at the outermost position. The seal ring 111 forms part of the surface 110 and abuts against the substrate W. A plurality of seal rings 111 may be provided to divide the space SP. With this configuration, it is possible to individually adjust the pressure of the helium gas in each space SP and make the surface temperature distribution of the substrate W during processing more uniform.

[0021] 1, the portion marked with the reference symbol "116" is the bottom surface of the space SP. Hereinafter, this portion will also be referred to as the "bottom surface 116." The seal ring 111, together with the dots 112 described below, is formed by digging down a part of the surface 110 to the position of the bottom surface 116.

[0022] The dots 112 are circular protrusions protruding from the bottom surface 116. A plurality of dots 112 are provided and are distributed approximately evenly on the mounting surface of the dielectric substrate 100. The upper end of each dot 112 forms part of the surface 110 and abuts against the substrate W. By providing a plurality of such dots 112, bending of the substrate W is suppressed.

[0023] The base plate 200 is a substantially disk-shaped member that supports the dielectric substrate 100 and the heater unit 300. The base plate 200 is formed of a metal material such as aluminum. The upper surface 210 of the base plate 200 in FIG. 1 is a "bonded surface" that is bonded to the heater unit 300 via a bonding layer 420.

[0024] A coolant flow path 250 for flowing a coolant is formed inside the base plate 200. When a process such as film formation is performed in the semiconductor manufacturing apparatus, a coolant is supplied to the coolant flow path 250 from the outside, thereby cooling the base plate 200. Heat generated in the substrate W during the process is transferred to the coolant via the helium gas in the space SP, the dielectric substrate 100, and the base plate 200, and is discharged to the outside together with the coolant.

[0025] An insulating film may be formed on the surface of the base plate 200. For example, an alumina film formed by thermal spraying can be used as the insulating film. By covering the surface of the base plate 200 with the insulating film, the dielectric strength of the base plate 200 can be increased.

[0026] The heater unit 300 generates heat when power is supplied from an external source, and heats the dielectric substrate 100. As will be described later, the heater unit 300 is provided with a plurality of heat generating parts 331, etc., and the amount of heat generated by each of the heat generating parts 331, etc. can be individually adjusted. By individually adjusting the amount of heat generated by each part, the in-plane temperature distribution of the substrate W during processing can be made closer to uniform.

[0027] The heater unit 300 is sandwiched between the dielectric substrate 100 and the base plate 200 and is bonded to each of them. The heater unit 300 and the dielectric substrate 100 are bonded via a bonding layer 410, and the heater unit 300 and the base plate 200 are bonded via a bonding layer 420. The bonding layers 410 and 420 are layers formed by, for example, hardening a silicone adhesive. A plurality of particulate fillers (fillers) for increasing thermal conductivity are disposed inside each of the bonding layers. For example, particles mainly composed of alumina can be used as the filler.

[0028] A specific configuration of the heater unit 300 will be described. In FIG. 2, the configuration of the heater unit 300 is shown as a schematic exploded view. As shown in the figure, the heater unit 300 has a support plate 310 (310A), an insulating layer 320, a sub-heater layer 330, an insulating layer 340, a main heater layer 350, an insulating layer 360, a bypass layer 370, an insulating layer 380, a support plate 310 (310B), and a power supply section 390. In this embodiment, the sub-heater layer 330, the main heater layer 350, and the bypass layer 370 are arranged in this order from the top, but the arrangement order of these may be different from that of this embodiment.

[0029] The support plate 310 is a substantially disk-shaped member, and is provided at each of the upper and lower ends of the heater unit 300 in FIG. 2. The support plate 310 provided at the upper end in FIG. 2 is also referred to as "support plate 310A" below. The support plate 310 provided at the lower end in FIG. 2 is also referred to as "support plate 310B" below. The support plate 310A is a portion bonded to the dielectric substrate 100 via a bonding layer 410, and the support plate 310B is a portion bonded to the base plate 200 via a bonding layer 420.

[0030] The pair of support plates 310A, 310B are members for reinforcing the entire heater unit 300 by sandwiching the entire sub-heater layer 330, the main heater layer 350, the bypass layer 370, etc. between them. In this embodiment, both the support plates 310A, 310B are made of metal, but they may be made of other materials (e.g., insulating materials). Note that, although a plurality of through holes are formed in each of the members constituting the heater unit 300, such as the support plate 310, for the purpose of passing lift pins through, etc., they are not shown in FIG. 2.

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

[0032] The sub-heater layer 330 is a part that generates heat when power is supplied from the outside. In Fig. 2, the sub-heater layer 330 is depicted as a single disk, but in reality, the sub-heater layer 330 is divided into a plurality of regions, and each region can be individually heated. The specific configuration of the sub-heater layer 330 will be described later.

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

[0034] The main heater layer 350, like the sub-heater layer 330 described above, is a part that receives power from an external source and generates heat. In Fig. 2, the main heater layer 350 is depicted as a single disk, but in reality, the main heater layer 350 is divided into a plurality of regions, and each region can be individually heated. The specific configuration of the main heater layer 350 will be described later.

[0035] The main heater layer 350 has a larger heat generation amount than the sub-heater layer 330 described above. The main heater layer 350 is intended to increase the temperature of the entire dielectric substrate 100 in a short period of time. The sub-heater layer 330 is intended to adjust the temperature of each part of the dielectric substrate 100 and make the in-plane temperature distribution of the substrate W closer to uniform. In this manner, in this embodiment, two heater layers are provided separately according to their respective roles. Alternatively, a configuration in which only one heater layer is provided may be used.

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

[0037] The bypass layer 370 is a layer for electrically connecting the 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, the bypass layer 370 is divided into a plurality of layers. By providing the bypass layer 370 in the middle of each electric path connecting the power supply unit 390 to the sub-heater layer 330 or the main heater layer 350, it becomes possible to adjust the position of the power supply unit 390, etc. Each of the divided bypass layers 370 has a portion welded to the sub-heater layer 330 or the main heater layer 350.

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

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

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

[0041] Instead of the above configuration, each power supply section 390 may be directly connected to either the sub-heater layer 330 or the main heater layer 350 without passing through the bypass layer 370 .

[0042] 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.

[0043] The sub-heater layer 330 includes a heat generating portion 331 which is a conductor drawn in a linear shape. Joule heat is generated in the heat generating portion 331 by the flow of an externally supplied current. The heat generating portion 331 is drawn individually in each region HA. FIG. 4 shows an example of the heat generating portion 331 drawn in one region HA. In each region HA, one linear heat generating portion 331 is drawn in a path that passes evenly through almost the entire range. In other words, one sub-heater layer 330 is provided for each of the 24 regions HA in total.

[0044] 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 functions as one sub-heater layer 330. A bypass layer 370 is connected to the pad portions 332, 333 by welding or the like.

[0045] The structure of the main heater layer 350 will now be described. Like the sub-heater layer 330, the main heater layer 350 is also divided into multiple regions, and each region can generate heat individually. Figure 5 shows an example of how the main heater layer 350 is divided from a top view. In this example, the main heater layer 350 is divided into a total of three regions HB.

[0046] The main heater layer 350 includes a heat generating portion 351 which is a conductor drawn in a linear shape. Joule heat is generated in the heat generating portion 351 by the flow of an externally supplied current. The heat generating portion 351 is drawn individually in each region HB. FIG. 6 shows an example of the heat generating portion 351 drawn in one region HB. In each region HB, one linear heat generating portion 351 is drawn in a path that passes evenly through almost the entire range. In other words, one main heater layer 350 is provided for each of the three regions HB.

[0047] Circular pad portions 352, 353 are formed on both ends of the heat generating portion 351. The heat generating portion 351 and the pad portions 352, 353 are formed, for example, by etching a thin metal foil, and the whole functions as one main heater layer 350. The bypass layer 370 is connected to the pad portions 352, 353 by welding or the like.

[0048] The specific shape of the heat generating part will be further described. Here, a part of heat generating part 331 will be described as an example, but the ideas for the shape of heat generating part 331 described below are also applicable to heat generating part 351.

[0049] The heater unit 300 has a plurality of through holes formed therethrough. Examples of such through holes include holes for inserting lift pins and holes for supplying helium gas to the space SP. In Fig. 7(A), the circular dotted lines marked with the symbol "HL" represent the above-mentioned through holes. In Fig. 7(A), the shape of the portion of the heat generating part 331 of this embodiment that is routed in the vicinity of the through hole HL is depicted in top view.

[0050] 7A, the portion marked with the symbol "CV" is a portion of the heat generating portion 331 where the extension direction is bent at an acute angle. This portion is also referred to as "bent portion CV" below.

[0051] Among the ridgelines of the heat generating part 331, the part surrounded by the dotted line DL in Fig. 7(A) is the ridgeline on the outer periphery of the bent portion CV. In this embodiment, the heat generating part 331 is formed so that the ridgeline is arc-shaped and has a radius of curvature of 0.1 mm or more. The heat generating part 331 of this embodiment has the same configuration in other parts than that shown in Fig. 7(A). That is, in the heat generating part 331, in all parts (bent portions) where the extension direction is bent at an acute angle, the ridgeline on the outer periphery of the bent portion is arc-shaped and has a radius of curvature of 0.1 mm or more.

[0052] FIG. 7B shows an example of the shape of the heat generating part 331 according to the comparative example. In this comparative example, the ridge of the bent part CV is not arc-shaped as described above. Therefore, as shown in the portion surrounded by the dotted line DL, the ridge on the outer periphery of the bent part CV has a pointed tip. In such a configuration, when the layers of FIG. 2 are laminated and pressed during the manufacture of the heater unit 300, the pointed tip of the heat generating part 331 may come into contact with the surrounding members (e.g., the insulating layer 320, etc.) as described above, and may damage the members. For example, if the insulating layer 320 is damaged, the dielectric strength of the portion may decrease.

[0053] 7(A), the heat generating parts 331 and 351 are formed so that the ridges on the outer periphery of all the bent parts CV are arc-shaped with a curvature radius of 0.1 mm or more. This configuration makes it possible to prevent the heat generating parts 331, etc. from damaging the surrounding members.

[0054] Furthermore, the heat generating portions 331, 351 of the heater unit 300 may have portions where the ridgeline on the outer periphery of the bent portion CV is not arc-shaped, or where the radius of curvature of the ridgeline on the outer periphery of the bent portion CV is less than 0.1 mm.

[0055] The radius of curvature of the outer circumferential edge of the bent portion CV is preferably 0.1 mm or more and 1.0 mm or less. By setting the radius of curvature within this range, it is possible to bend the heat generating portion 331 etc. with a relatively high degree of freedom while maintaining a shape that does not damage the surrounding members as described above, and to make the distribution of the heat generation amount throughout the entire portion closer to uniformity.

[0056] When the heat generating portion 331 and the like are sandwiched between resin sheets such as the insulating layer 320 and the like as in this embodiment, it is particularly effective to set the radius of curvature of the ridge line of the bent portion CV to 0.1 mm or more.

[0057] A second embodiment will be described below. In the following, differences from the first embodiment will be mainly described, and descriptions of commonalities with the first embodiment will be omitted as appropriate.

[0058] 8, in the electrostatic chuck 10 according to this embodiment, the heater unit 300 is not provided between the dielectric substrate 100 and the 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 in the first embodiment, and is a layer formed by curing a silicone adhesive.

[0059] In this embodiment, a heater layer 300A is embedded inside the dielectric substrate 100. The heater layer 300A generates heat when power is supplied from the outside, and heats the dielectric substrate 100. The heater layer 300A is a thin, flat layer made of a metal material (i.e., a conductor) such as tungsten, similar to the attraction electrode 130, and is disposed parallel to the surface 110.

[0060] In top view, the heater layer 300A is routed linearly. The shape of the heater layer 300A is the same as that of the heat generating part 331 in the first embodiment. That is, the heater layer 300A has bent parts CV whose extension direction is bent at an acute angle, like the heat generating part 331 in FIG. 7(A). Moreover, the heater layer 300A is formed so that the ridges on the outer periphery side of almost all of the bent parts CV are arc-shaped, and the radius of curvature is 0.1 mm or more.

[0061] A plurality of green sheets are laminated, and the entire laminate is pressurized and fired to manufacture the dielectric substrate 100. On some of the green sheets, the attraction electrodes 130 and the heater layers 300A are formed in advance by screen printing.

[0062] At this time, if a part of the heater layer 300A is sharp like the heat generating part 331 in Fig. 7(B), the sharp tip of the heater layer 300A may hit the surrounding green sheet and damage the green sheet. However, in the heater layer 300A of this embodiment, as described above, the ridge lines on the outer periphery side of almost all the bent parts CV are formed in an arc shape with a curvature radius of 0.1 mm or more. Therefore, it is possible to prevent the heater layer 300A from damaging the surrounding green sheet.

[0063] 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]

[0064] 10: Electrostatic chuck 100: Dielectric substrate 110: Face 300: Heater unit 331, 351: Heat generating part CV: bending part

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, The heater has a heat generating portion which is a conductor wired in a linear shape and generates heat when power is supplied from an external source, When viewed from a direction perpendicular to the placement surface, The heat generating portion includes a bent portion where the extension direction is bent at an acute angle, The electrostatic chuck is characterized in that the radius of curvature of the ridge line on the outer periphery of the bent portion is 0.1 mm or more.

2. 2. The electrostatic chuck according to claim 1, wherein the radius of curvature of the ridge line is 1.0 mm or less.

3. 3. The electrostatic chuck according to claim 2, wherein the heat generating portion is sandwiched between resin sheets.

4. 3. The electrostatic chuck according to claim 2, wherein the heat generating portion is embedded inside the dielectric substrate.

Images