Electrostatic chuck

Abstract

To provide an electrostatic chuck capable of making the in-plane temperature distribution of a substrate during processing more uniform than ever before.SOLUTION: An electrostatic chuck 10 includes a dielectric substrate 100 having a through hole 150 formed therein, an adsorption electrode 130 built into the dielectric substrate 100, and a heater unit 300 that heats the dielectric substrate 100. The adsorption electrode 130 includes a circular opening 131 formed therein that overlaps with the through hole 150 in a top view, and the heater unit 300 includes a circular opening 302 formed therein that overlaps with the through hole 150, and the diameter D2 of the opening 302 is larger than the diameter D1 of the opening 131.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] For example, in a semiconductor manufacturing apparatus such as an etching apparatus, 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 includes a dielectric substrate provided with an attracting electrode and a base plate supporting the dielectric substrate, which are joined together. 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. When the substrate is being processed in the semiconductor manufacturing apparatus, the dielectric substrate is cooled by the base plate. This allows the temperature of the substrate placed on the dielectric substrate to be maintained at an appropriate temperature.

[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 outside the dielectric substrate, or may be provided inside the dielectric substrate, as described in Patent Document 1 below, for example. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-181841 A Summary of the Invention [Problem to be solved by the invention]

[0005] The electrostatic chuck has a through hole formed through the dielectric substrate, the base plate, etc. An example of such a through hole is a lift pin hole (pinhole) for inserting a lift pin, as described in the above Patent Document 1.

[0006] In the area of ​​the dielectric substrate near the through hole, heat is not easily dissipated toward the base plate, and the temperature is likely to rise. Therefore, if this area is heated by the heater in the same way as other areas, the temperature of this area will become locally high, and there is a possibility that the temperature of the substrate directly above it will also become locally high.

[0007] The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrostatic chuck that can make the in-plane temperature distribution of a substrate during processing more uniform than ever before. [Means for solving the problem]

[0008] In order to solve the above problems, the electrostatic chuck according to the present invention includes a dielectric substrate having a mounting surface on which an object to be attracted is mounted and having a through hole formed therethrough in a direction perpendicular to the mounting surface, an attraction electrode built into the dielectric substrate, and a heater for heating the dielectric substrate. When viewed in a direction perpendicular to the mounting surface, the attraction electrode has a first circular opening that overlaps with the through hole, and the heater has a second circular opening that overlaps with the through hole, the diameter of the second opening being larger than the diameter of the first opening.

[0009] In an electrostatic chuck having such a configuration, the diameter of the second opening formed in the heater is large in the portion of the dielectric substrate near the through hole, i.e., in the portion where local temperature rise is likely to occur due to small heat dissipation toward the base plate. Since the amount of heat applied to the portion by the heater is small and local temperature rise is suppressed, the temperature distribution within the surface of the substrate during processing can be made more uniform than before. Effect of the Invention

[0010] According to the present invention, it is possible to provide an electrostatic chuck that can make the in-plane temperature distribution of a substrate during processing more uniform than ever before. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view illustrating a schematic configuration of an electrostatic chuck according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged view of a portion of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

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

[0014] 1 shows, in a schematic cross-sectional view, the configuration of an electrostatic chuck 10 in a state in which the electrostatic chuck 10 attracts and holds a substrate W. The electrostatic chuck 10 includes a dielectric substrate 100, a base plate 200, and a heater unit 300.

[0015] The dielectric substrate 100 is a substantially disk-shaped member made of a sintered ceramic body. The dielectric substrate 100 contains, for example, high-purity aluminum oxide (Al2O3), but may contain other materials. The purity, type, and additives of the ceramics in the dielectric substrate 100 can be appropriately set in consideration of the plasma resistance and other properties required of the dielectric substrate 100 in semiconductor manufacturing equipment.

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

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

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

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

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

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

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

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

[0024] A coolant flow path 270 for flowing a coolant is formed inside the base plate 200. When a process such as etching is performed in the semiconductor manufacturing apparatus, a coolant is supplied to the coolant flow path 270 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 the outside, and heats the dielectric substrate 100. A heat generating portion (not shown) made of a linearly routed conductor is embedded inside the heater unit 300. The heat generating portion is sandwiched from above and below in FIG. 1 by sheet-like insulating material such as polyimide.

[0027] When power is supplied to the heater unit from the outside, Joule heat is generated in the heat generating portion, increasing the temperature of the entire heater unit 300. A terminal (not shown) for receiving power from the outside protrudes from the heater unit 300 toward the base plate 200, and is housed inside a through hole (not shown) formed in the base plate 200.

[0028] The heater unit 300 is provided with a plurality of heat generating parts, and the heat generation amount of each heat generating part can be adjusted individually. By adjusting the heat generation amount of each part individually, the in-plane temperature distribution of the substrate W during processing can be made closer to uniform.

[0029] 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.

[0030] A through hole 150 is formed in the dielectric substrate 100. The through hole 150 is a hole for inserting a lift pin (not shown) provided in a semiconductor manufacturing device. The through hole 150 is formed so as to penetrate the dielectric substrate 100 in a straight line along a direction perpendicular to the surface 110, which is the mounting surface (the vertical direction in FIG. 1). A total of three through holes 150 are formed, and are disposed so as to be equidistant from each other by 120 degrees when viewed from above, but only one of them is shown in FIG. 1. The substrate W is attached to and detached from the surface 110 of the dielectric substrate 100 by the lift pin that moves up and down through the through hole 150.

[0031] A seal ring 160 is formed on the surface 110 side of the dielectric substrate 100. The seal ring 160 is an annular protrusion surrounding the through hole 150. When viewed from above, the center of the through hole 150 and the center of the seal ring 160 coincide with each other. The tip surface of the seal ring 160 forms part of the surface 110, which is the mounting surface, and abuts against the substrate W. The formation of the seal ring 160 blocks the flow of gas between the inside of the through hole 150 and the space SP.

[0032] A circular opening 131 is formed in the chucking electrode 130 at a position overlapping with the through hole 150 in a top view. The center of the opening 131 in a top view coincides with the center of the through hole 150. The diameter of the opening 131 is larger than the diameter of the through hole 150. The opening 131 is formed to prevent the chucking electrode 130 from being exposed at the inner surface of the through hole 150. The opening 131 corresponds to a "first opening" in this embodiment. It is preferable that the radius of the opening 131 is as small as possible within a range in which dielectric breakdown via the inner surface of the through hole 150 does not occur.

[0033] In the base plate 200, a through hole 250 is formed at each position overlapping with the through hole 150 in a top view. The through hole 250 is formed so as to linearly penetrate the base plate 200 along a direction perpendicular to the surface 110, which is the mounting surface. The central axis of the through hole 250 coincides with the central axis of the through hole 150.

[0034] A sleeve 260, which is a cylindrical member, is disposed inside the through hole 250. The sleeve 260 is formed of an insulating material such as alumina. A through hole 261 formed inside the sleeve 260 is connected to the through hole 150. The inner diameter of the through hole 261 is the same as the inner diameter of the through hole 150. In addition, the central axis of the through hole 261 coincides with the central axis of the through hole 150. The through hole 261 functions as a hole for inserting a lift pin, similar to the through hole 150.

[0035] 1 protrudes further upward beyond the surface 210 of the base plate 200 and abuts against the surface 120 of the dielectric substrate 100. This protruding portion is accommodated inside an opening 302 formed in the heater unit 300.

[0036] The openings 302 are circular openings in a top view. The openings 302 are formed in the heater unit 300 at positions that overlap with the through holes 150 in a top view, and penetrate the heater unit 300. The openings 302 correspond to a "second opening" in this embodiment.

[0037] 2 shows an enlarged view of the through hole 150 and its neighboring portion in FIG. 1. "D1" shown in FIG. 2 is the diameter of the opening 131 formed in the chucking electrode 130. Hereinafter, this diameter will also be referred to as "diameter D1." "D2" is the diameter of the opening 302 formed in the heater unit 300. Hereinafter, this diameter will also be referred to as "diameter D2." "D3" is the outer diameter of the seal ring 160 formed in the dielectric substrate 100. Hereinafter, this outer diameter will also be referred to as "outer diameter D3."

[0038] In this embodiment, the opening 302 of the heater unit 300 is formed so that the diameter D2 is larger than the diameter D1.

[0039] The reason for adopting such a configuration will be explained below. When the substrate W is being processed in the semiconductor manufacturing equipment, the dielectric substrate 100 is heated by energy from the plasma and the heater unit 300, and is cooled by the base plate 200. The temperature of each part of the substrate W changes according to the balance between such heating and cooling.

[0040] Directly below the through hole 150, a through hole 250 is formed in the base plate 200. Also, the coolant flow path 270 of the base plate 200 is routed so as to avoid the through hole 250. For this reason, in the portion of the dielectric substrate 100 near the through hole 150, heat is less easily dissipated toward the dielectric substrate 100-base plate 200 (compared to other portions).

[0041] Therefore, when the area near the through hole 150 is heated by the heater unit 300 in the same manner as other areas, the temperature of that area becomes locally high, and there is a possibility that the temperature of the substrate W directly above that area also becomes locally high.

[0042] Therefore, in this embodiment, as described above, in the portion of the dielectric substrate 100 near the through hole 150, i.e., the portion where local temperature rise is likely to occur due to small heat dissipation toward the base plate 200, the diameter D2 of the opening 302 formed in the heater unit 300 is made larger than the diameter D1. Since the amount of heat applied to the portion by the heater unit 300 is reduced and local temperature rise is suppressed, it is possible to make the in-plane temperature distribution of the substrate W during processing more uniform than before.

[0043] Furthermore, in this embodiment, the opening 131 of the attraction electrode 130 is formed so that the diameter D1 is smaller than the outer diameter D3.

[0044] In such a configuration, the chucking electrode 130 overlaps a part of the seal ring 160 when viewed from above. Since the chucking force between the seal ring 160 and the substrate W in contact therewith is increased, the gas blocking performance of the seal ring 160 can be fully exhibited.

[0045] Incidentally, in a configuration in which the seal ring 160 is provided around the through hole 150 as in this embodiment, heat transfer via the seal ring 160 is promoted, which tends to make it difficult to maintain a balance in heat transfer between the substrate W. If the balance of heat transfer is lost, the substrate W may be locally overcooled at the position of the seal ring 160, or conversely, may be locally overheated.

[0046] 2, in this embodiment, the opening 302 of the heater unit 300 is formed so that the diameter D2 is larger than the outer diameter D3. In this configuration, the influence of the heater unit 300 on the heat transfer through the seal ring 160 is suppressed to a small extent. As a result, it is possible to prevent a situation in which the balance of the heat transfer through the seal ring 160 is lost.

[0047] In the above, a configuration has been described in which a heater for heating the dielectric substrate 100 is provided outside the dielectric substrate 100 in a unitized state as the heater unit 300. However, the above-described configuration can also be applied to a configuration in which a heater is provided inside the dielectric substrate 100.

[0048] That is, a heat generating portion made of a conductor wired in a linear shape may be embedded inside the dielectric substrate 100 as a heater. In this case, the heat generating portion may be configured not to be wired in a circular region centered on the through hole 150 when viewed from above. This region corresponds to the "second opening" in this example. By making the diameter D2 of this region larger than the diameter D1 or smaller than the outer diameter D3, it is possible to achieve the same effect as that described in this embodiment.

[0049] An opening 302 may be formed in the heater unit 300 directly below a through hole (not shown) formed in the dielectric substrate 100 for supplying helium gas to the space SP, rather than directly below the through hole 150 for passing the lift pin therethrough, and a configuration similar to that of this embodiment may be applied.

[0050] 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]

[0051] 10: Electrostatic chuck 100: Dielectric substrate 110: Face 130: Adsorption electrode 131:Aperture 150:Through hole 160: Seal ring 300: Heater unit 302:Aperture W: Substrate

Claims

1. a dielectric substrate having a mounting surface on which an object to be attached is placed and having a through hole formed therein and extending in a direction perpendicular to the mounting surface; An adsorption electrode embedded in the dielectric substrate; a heater for heating the dielectric substrate, When viewed from a direction perpendicular to the placement surface, a first circular opening overlapping with the through hole is formed in the chucking electrode, The heater has a second circular opening overlapping the through hole, The electrostatic chuck, wherein the second opening has a diameter larger than the diameter of the first opening.

2. a seal ring is formed on the mounting surface side of the dielectric substrate, the seal ring being an annular protrusion surrounding the through hole, the tip surface of the seal ring being a part of the mounting surface; 2. The electrostatic chuck of claim 1, wherein the diameter of the first opening is smaller than an outer diameter of the seal ring.

3. a seal ring is formed on the mounting surface side of the dielectric substrate, the seal ring being an annular protrusion surrounding the through hole, the tip surface of the seal ring being a part of the mounting surface; 2. The electrostatic chuck of claim 1, wherein the diameter of the second opening is greater than an outer diameter of the seal ring.

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