Electrostatic chuck

Abstract

To provide an electrostatic chuck capable of stably performing power supply to an internal electrode via a conductive member.SOLUTION: An electrostatic chuck 10 comprises: a dielectric substrate 100; a heater 140 which is provided inside of the dielectric substrate 100; a power supplied part 150 which is a conductor provided on a bottom face 122 of a recess 121 formed on the dielectric substrate 100 and electrically coupled to the heater 140; a conductive member 400 which is inserted inside of the recess 121; and a brazing material 450 which covers a periphery of the conductive member 400 and is joined to the power supplied part 150. The closer the brazing material 450 is positioned to the power supplied part 150, the thicker the brazing material is made. The outside of the brazing material 450 is supported by a junction layer 300.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] For example, in a semiconductor manufacturing apparatus such as an etching apparatus, an electrostatic chuck is provided as a device for adsorbing and holding a substrate such as a silicon wafer to be processed. The electrostatic chuck includes a dielectric substrate provided with an adsorption electrode, and a base plate for supporting the dielectric substrate, and these have a configuration in which they are joined to each other. When a voltage is applied to the adsorption electrode, an electrostatic force is generated, and the substrate placed on the dielectric substrate is adsorbed and held.

[0003] An internal electrode is provided inside the dielectric substrate. The internal electrode is, for example, a heater for heating the dielectric substrate. The above-described adsorption electrode, RF electrode, etc. may be provided inside the dielectric substrate as the internal electrode. As described in Patent Document 1 below, a conductive member for supplying power to the internal electrode is connected from the side of the dielectric substrate opposite to the placement surface.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As the conductive member, for example, a lead wire, a rod-shaped electrode terminal, etc. are used. When an external force is applied to the conductive member, the connection portion of the conductive member may be damaged or the conductive member may come off, resulting in the possibility of not being able to supply power to the internal electrode.

[0006] The present invention has been made in view of such problems, and an object thereof is to provide an electrostatic chuck capable of stably supplying power to an internal electrode via a conductive member.

Means for Solving the Problems

[0007] In order to solve the above problems, an electrostatic chuck according to the present invention includes a dielectric substrate, an internal electrode provided inside the dielectric substrate, and a conductor provided at the bottom of a recess formed in the dielectric substrate, the conductor being electrically connected to the internal electrode and being a power supply receiving portion, a conductive member inserted inside the recess, and a brazing material that covers the periphery of the conductive member and is joined to the power supply receiving portion. The brazing material becomes thicker as it approaches the power supply receiving portion, and the outside of the brazing material is supported by an insulating member.

[0008] In the electrostatic chuck having the above configuration, the power supply receiving portion and the conductive member are electrically connected via the brazing material, and the brazing material is supported from the outside by the insulating member. Therefore, even when an external force is applied to the conductive member, deformation of the connection portion of the conductive member and stress accompanying the deformation can be suppressed by the insulating member. Further, the brazing material has a shape that becomes thicker as it approaches the power supply receiving portion, and its outside is supported by the insulating member. Therefore, even when a force in a direction away from the power supply receiving portion is applied to the conductive member or the brazing material, the connection state between the conductive member and the power supply receiving portion can be maintained.

Effects of the Invention

[0009] According to the present invention, it is possible to provide an electrostatic chuck capable of stably supplying power to an internal electrode via a conductive member.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Best Mode for Carrying Out the Invention

[0011] Hereinafter, this embodiment will be described with reference to the accompanying drawings. For ease of understanding the description, the same reference numerals are given to the same components in each drawing as much as possible, and redundant descriptions are omitted.

[0012] The electrostatic chuck 10 according to this embodiment adsorbs and holds a substrate W to be processed by electrostatic force inside a semiconductor manufacturing apparatus (not shown) such as an etching apparatus. The substrate W to be adsorbed is, for example, a silicon wafer. The electrostatic chuck 10 may be used in an apparatus other than a semiconductor manufacturing apparatus.

[0013] FIG. 1 schematically shows a cross-sectional view of the configuration of the electrostatic chuck 10 in a state where the substrate W is adsorbed and held. The electrostatic chuck 10 includes a dielectric substrate 100 and a base plate 200.

[0014] The dielectric substrate 100 is a substantially disk-shaped member made of a ceramic sintered body. The dielectric substrate 100 contains, for example, high-purity aluminum oxide (Al2O3), but may contain other materials. The purity, type, additives, etc. of the ceramics in the dielectric substrate 100 can be appropriately set in consideration of the plasma resistance required for the dielectric substrate 100 in a semiconductor manufacturing apparatus.

[0015] Of the dielectric substrate 100, the upper surface 110 in FIG. 1 is the "placement surface" on which the substrate W is placed. Also, the lower surface 120 of the dielectric substrate 100 in FIG. 1 is the "surface to be joined" that is joined to the base plate 200 via the joining layer 300. The direction along the direction perpendicular to the surface 110 and the viewpoint when looking at the electrostatic chuck 10 from the surface 110 side will also be hereinafter referred to as "top view".

[0016] An adsorption electrode 130 is embedded inside the dielectric substrate 100. The adsorption electrode 130 is a thin flat plate-shaped layer formed of a metal material such as tungsten, for example, and is arranged to be parallel to the surface 110. As the material of the adsorption electrode 130, in addition to tungsten, molybdenum, platinum, palladium, etc. may also be used. When a voltage is applied to the adsorption electrode 130 from the outside via the power supply path 13, an electrostatic force is generated between the surface 110 and the substrate W, whereby the substrate W is adsorbed and held. The adsorption electrode 130 may be provided only one as a so-called "unipolar" electrode as in this embodiment, or may be provided two as a so-called "bipolar" electrode.

[0017] In FIG. 1, the entire power supply path 13 is drawn in a simplified manner. The portion inside the dielectric substrate 100 of the power supply path 13 is configured as, for example, an elongated via (hole) filled with a conductor, and an electrode terminal (not shown) is provided at its lower end. The portion of the power supply path 13 passing through the base plate 200 is a rod-shaped metal (bus bar) having one end connected to the above electrode terminal. A through hole (not shown) for inserting the metal is formed in the base plate 200. As the configuration of the power supply path 13, a configuration similar to the power supply path 14 described later may be used.

[0018] Inside the dielectric substrate 100, in addition to the above adsorption electrode 130, a heater 140 is also embedded. The heater 140 is an internal electrode linearly routed along a plane parallel to the surface 110 as a heater for heating the dielectric substrate 100. By adjusting the calorific value of the heater 140, it is possible to appropriately maintain the temperature of the dielectric substrate 100 during the processing of the substrate W.

[0019] The heater 140 is provided at a height position on the surface 120 side with respect to the adsorption electrode 130. When power is supplied to the heater 140 from the outside through the power supply path 14, Joule heat is generated in the heater 140, and the dielectric substrate 100 is heated. Although at least two or more power supply paths 14 are provided, only one power supply path 14 is schematically depicted in FIG. 1. Also, in FIG. 1, the entire power supply path 14 is depicted in a simplified manner. The specific configuration of the power supply path 14 will be described later.

[0020] In a top view, a configuration may be adopted in which the heaters 140 are individually arranged for each of the plurality of regions of the dielectric substrate 100. By adopting such a configuration, it becomes possible to individually adjust the temperature of each region of the dielectric substrate 100 and make the in-plane temperature distribution of the substrate W closer to uniform. In this case, a pair of power supply paths 14 will be provided corresponding to each of the regions.

[0021] As shown in FIG. 1, a space SP is formed between the dielectric substrate 100 and the substrate W. When a process such as etching is performed in the semiconductor manufacturing apparatus, helium gas for temperature adjustment is supplied to the space SP from the outside through a gas hole (not shown). By interposing helium gas between the dielectric substrate 100 and the substrate W, the thermal resistance between the two is adjusted, and thereby the temperature of the substrate W is maintained at an appropriate temperature. Note that the gas for temperature adjustment supplied to the space SP may be a gas of a type different from helium.

[0022] A seal ring 111 and dots 112 are provided on the surface 110 which is the placement surface, and the above-described space SP is formed around these.

[0023] The seal ring 111 is a wall that partitions the space SP at the outermost peripheral position. The seal ring 111 is an annular protrusion formed on the surface 110 side. The tip (the upper end in FIG. 1) of the seal ring 111 forms a part of the surface 110 and abuts against the substrate W. The tip of the seal ring 111 can be said to be the outermost peripheral portion of the surface 110 which is the placement surface.

[0024] A plurality of seal rings 111 may be provided so as to divide the space SP. With such a configuration, the pressure of the helium gas in each space SP can be individually adjusted, and it becomes possible to make the surface temperature distribution of the substrate W during processing closer to uniform.

[0025] In FIG. 1, the portion marked with 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 is formed as a result of digging a part of the surface 110 down to the position of the bottom surface 116 together with the dot 112 described below.

[0026] The dot 112 is a circular protrusion protruding from the bottom surface 116. A plurality of dots 112 are provided and are arranged substantially evenly dispersed on the mounting surface of the dielectric substrate 100. The tip of each dot 112 forms a part of the surface 110 and contacts the substrate W. By providing a plurality of such dots 112, the deflection of the substrate W is suppressed.

[0027] The base plate 200 is a substantially disk-shaped member that supports the dielectric substrate 100. The base plate 200 is formed of a metal material such as aluminum, for example. The base plate 200 is joined to the surface 120 of the dielectric substrate 100 via a joining layer 300. Among the base plate 200, the upper surface 210 in FIG. 1 is a “surface to be joined” that is joined to the dielectric substrate 100.

[0028] The joining layer 300 is a layer provided between the dielectric substrate 100 and the base plate 200 and joins the two. The joining layer 300 is obtained by curing an adhesive made of an insulating material. In the present embodiment, a silicone adhesive is used as the adhesive. However, the joining layer 300 may be obtained by curing another type of adhesive. In any case, as the material of the joining layer 300, it is preferable to use a material having as high a thermal conductivity as possible so that the thermal resistance between the dielectric substrate 100 and the base plate 200 is reduced.

[0029] An insulating film may be formed on the surface of the base plate 200. As the insulating film, for example, an alumina film formed by spraying can be used. By covering the surface of the base plate 200 with the insulating film, the dielectric breakdown voltage of the base plate 200 can be increased.

[0030] Inside the base plate 200, a refrigerant flow path 250 for passing a refrigerant is formed. When a process such as etching is performed in the semiconductor manufacturing apparatus, the refrigerant is supplied from the outside to the refrigerant flow path 250, and thereby the base plate 200 is cooled. The heat generated in the substrate W during the process is transmitted to the refrigerant through 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 refrigerant.

[0031] The specific configuration of the power supply path 14 will be described with reference to FIG. 2. The power supply path 14 includes a power supply target portion 150, a via 151, a conductive member 400, and a brazing material 450.

[0032] In a portion of the surface 120 of the dielectric substrate 100 corresponding to the power supply path 14, a recess 121 is formed. The recess 121 is formed so as to retreat a part of the surface 120 toward the surface 110 side, and its shape in a top view is circular. The bottom surface 122 of the recess 121 is at a height position closer to the surface 120 side than the heater 140.

[0033] The power supply target portion 150, which is a part of the power supply path 14, is a conductor provided so as to cover substantially the entire bottom surface 122 of the recess 121. As the power supply target portion 150, for example, a plate-like member made of a metal such as molybdenum or tungsten can be used. A material obtained by applying and curing a conductive adhesive to the bottom surface 122 may be used as the power supply target portion 150.

[0034] The power supply unit 150 is electrically connected to the heater 140 via the via 151. The via 151 is an electric circuit formed by filling a hole formed to reach from the bottom surface 122 of the recess 121 to the heater 140 with a metal material such as tungsten, for example.

[0035] As described above, the power supply unit 150 is a conductor provided at the bottom of the recess 121 formed in the dielectric substrate 100 and is in an electrically connected state to the heater 140 (internal electrode). The power supply unit 150 is a part that receives power supply from the conductive member 400 described below.

[0036] Instead of the above-described aspect, an aspect may be adopted in which the heater 140 is exposed on the bottom surface 122 of the recess 121. In this case, the via 151 is unnecessary. In such a configuration, the exposed portion of the heater 140 is used as the power supply unit 150.

[0037] The conductive member 400 is a member for guiding the power supplied from the outside to the above-described power supply unit 150. In order to enable the arrangement of the conductive member 400, a through hole 230 is formed in a portion of the base plate 200 that overlaps the recess 121 in a top view. The through hole 230 is a circular through hole in a top view and penetrates the base plate 200 along a direction perpendicular to the surface 210. The central axis of the through hole 230 coincides with the central axis of the recess 121.

[0038] The conductive member 400 includes a terminal 410 and a lead wire 420, and a part of it is inserted inside the recess 121.

[0039] Terminal 410 is a metal member for receiving the tip of a lead wire 420 described later, and is disposed inside the recess 121. Terminal 410 has a cylindrical portion 411 and a diameter-expanded portion 412. The cylindrical portion 411 is a cylindrical part, and its central axis is parallel to the central axis of the recess 121. One end of the cylindrical portion 411 (the upper end portion in FIG. 2) is connected to the diameter-expanded portion 412 described below. The other end of the cylindrical portion 411 (the lower end portion in FIG. 2) is open toward the through hole 230 side.

[0040] The diameter-expanded portion 412 is a disk-shaped part. The shape of the diameter-expanded portion 412 in top view is circular, and its diameter is larger than the outer diameter of the cylindrical portion 411. The center of the diameter-expanded portion 412 in top view overlaps with the central axis of the cylindrical portion 411. The surface of the diameter-expanded portion 412 opposite to the cylindrical portion 411 is disposed to face the power supply-receiving portion 150 and is electrically connected to the power supply-receiving portion 150. The diameter-expanded portion 412 may be in direct contact with the power supply-receiving portion 150, or may be connected to the power supply-receiving portion 150 via a part of a brazing material 450 described later.

[0041] The lead wire 420 electrically connects between a power supply (not shown) installed outside and the terminal 410. The lead wire 420 is a flexible member and has a conductor portion 421 and an insulating covering portion 422 covering the outside thereof. In the vicinity of the end portion on the terminal 410 side of the lead wire 420, the conductor portion 421 is exposed. A part of the thus-exposed conductor portion 421 is inserted inside the cylindrical portion 411. Instead of the lead wire 420, a rod-shaped electrode terminal or the like may be used.

[0042] The brazing material 450 is a member for joining and electrically connecting the entire power supply receiving portion 150, the terminal 410, and the lead wire 420, and is, for example, silver brazing. The brazing material 450 covers the entire terminal 410 and a part of the lead wire 420 among the conductive members 400 from the surroundings. A part of the brazing material 450 is joined to the surface of the power supply receiving portion 150. The brazing material 450 enters inside the cylindrical portion 411 and is also joined to the tip portion of the lead wire 420 and the inner surface of the cylindrical portion 411. The brazing material 450 electrically connects the lead wire 420 and the heater 140.

[0043] As shown in FIG. 2, the brazing material 450 is formed so as to gradually become thicker as it approaches the power supply receiving portion 150 from the base plate 200 side. In the present embodiment, since the terminal 410 has the cylindrical portion 411 and the diameter-expanded portion 412, the shape of the brazing material 450 disposed so as to surround the periphery of the terminal 410 is likely to naturally become the above-described shape during curing.

[0044] The periphery of the brazing material 450 is filled with a bonding layer 300 which is an insulating member. As a result, the outside of the brazing material 450 is supported by the bonding layer 300. Such a configuration can be realized by connecting between the power supply receiving portion 150 and the conductive member 400 in advance using the brazing material 450 during the manufacture of the electrostatic chuck 10, and then joining between the dielectric substrate 100 and the base plate 200 using the bonding layer 300 (for example, a silicone adhesive).

[0045] In such a configuration, the power supply receiving portion 150 and the conductive member 400 are electrically connected via the brazing material 450, and the brazing material 450 is supported from the outside by the bonding layer 300 (insulating member). Therefore, even when an external force is applied to the conductive member 400, it is possible to suppress deformation of the connection portion of the conductive member 400 (for example, the portion between the power supply receiving portion 150 and the terminal 410, etc.) and the stress accompanying the deformation by the bonding layer 300.

[0046] Also, the brazing material 450 has a shape that becomes thicker as it approaches the power supply receiving part 150, and its outer side is supported by the bonding layer 300. Therefore, even when a force in the direction away from the power supply receiving part 150 is applied to the conductive member 400 or the brazing material 450, the connection state between the conductive member 400 and the power supply receiving part 150 can be maintained.

[0047] In the present embodiment, as described above, a part of the bonding layer 300 is used as an insulating member that supports the outside of the brazing material 450. Instead of such an aspect, an aspect in which a member different from the bonding layer 300 is used as the "insulating member" may be adopted. However, from the viewpoint of suppressing component costs and manufacturing costs, it is preferable to also use a part of the bonding layer 300 that joins the dielectric substrate 100 and the base plate 200 as the "insulating member" that supports the brazing material 450 as in the present embodiment.

[0048] A configuration may be adopted in which the lead wire 420 and the power supply receiving part 150 are directly connected via the brazing material 450 without using the terminal 410. Also in this case, by joining the like so that most of the power supply receiving part 150 is in a wetted state by the brazing material 450, it is possible to make the shape of the brazing material 450 thicker as it approaches the power supply receiving part 150.

[0049] The "internal electrode" provided inside the dielectric substrate 100 and electrically connected to the conductive member 400 may be the heater 140 as in the present embodiment, or may be other electrodes. For example, it may be the adsorption electrode 130, the RF electrode, or the like. However, since a relatively large current flows through the heater 140 compared to the adsorption electrode 130, the RF electrode, or the like, abnormal heat generation may occur if the connection state of the conductive member 400 deteriorates. Therefore, adopting the configuration of the power supply path 14 as shown in FIG. 2 has a particularly great effect of stably maintaining the connection state of the conductive member 400.

[0050] The above-described embodiments have been explained with reference to specific examples. However, the present disclosure is not limited to these specific examples. As long as those skilled in the art appropriately make design changes to these specific examples and have the features of the present disclosure, they are included in the scope of the present disclosure. Each element, its arrangement, conditions, shape, etc. included in the above-described specific examples are not limited to those illustrated and can be changed as appropriate. Each element included in the above-described specific examples can be appropriately combined as long as no technical contradiction occurs.

Explanation of Reference Numerals

[0051] 10: Electrostatic chuck 100: Dielectric substrate 121: Recess 140: Heater 150: Power supply receiving part 200: Base plate 300: Bonding layer 400: Conductive member 410: Terminal 411: Cylindrical part 412: Diameter-expanded part

Claims

1. A dielectric substrate, an internal electrode provided inside the dielectric substrate, a conductor provided at the bottom of a recess formed in the dielectric substrate and electrically connected to the internal electrode, which is a power supply receiving portion, a conductive member inserted inside the recess, a brazing material that covers the periphery of the conductive member and is joined to the power supply receiving portion, and the brazing material becomes thicker as it approaches the power supply receiving portion, wherein an outer side of the brazing material is supported by an insulating member, characterized in that it is an electrostatic chuck.

2. a base plate for supporting the dielectric substrate, and a bonding layer for bonding between the dielectric substrate and the base plate, further comprising, the recess is formed on a surface of the dielectric substrate on the side of the base plate, the electrostatic chuck according to claim 1, wherein the insulating member is a part of the bonding layer.

3. the electrostatic chuck according to claim 1, wherein the internal electrode is a heater for heating the dielectric substrate.

4. the conductive member, a cylindrical portion that is a cylindrical shape, a diameter-expanded portion that is a disk shape and has a diameter larger than an outer diameter of the cylindrical portion, and the electrostatic chuck according to claim 1, wherein the diameter-expanded portion faces the power supply receiving portion.

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