Electrostatic chuck

Abstract

To provide an electrostatic chuck that can increase the degree of freedom in routing a refrigerant flow path while preventing discharge.SOLUTION: An electrostatic chuck 10 includes a dielectric substrate 100 having a through hole 140 formed therein, a base plate 200 joined to the dielectric substrate 100 and having a coolant flow path 250 formed therein through which a coolant passes, and an insulating member 400 fixed to the base plate 200, the insulating member 400 having a through hole 440 formed to connect to the through hole 140. The insulating member 400 includes a first portion 410 that is a portion including an end portion on the dielectric substrate 100 side, and a second portion 420 that is a portion adjacent to the first portion 410. In a top view, the outer shape of the first portion 410 is larger than the outer shape of the second portion 420.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] For example, semiconductor manufacturing equipment such as an etching apparatus 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 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, attracting and holding a substrate placed on the dielectric substrate.

[0003] During processes such as etching, it is necessary to maintain the substrate at an appropriate temperature. For this reason, a coolant flow path is formed inside the base plate to allow a coolant to pass through. Heat from the substrate is transferred to the coolant through the dielectric substrate and the base plate, and is then discharged to the outside together with the coolant.

[0004] Furthermore, as described in Patent Document 1, for example, the electrostatic chuck is provided with through holes that penetrate the entire dielectric substrate and the base plate. Examples of such through holes include lift pin holes for inserting lift pins and gas holes for supplying inert gas between the silicon wafer and the dielectric substrate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-347559 Summary of the Invention [Problem to be solved by the invention]

[0006] For ease of explanation, the portion of the through hole provided in the dielectric substrate will hereinafter be referred to as the "first through hole," and the portion of the through hole provided in the base plate will hereinafter be referred to as the "second through hole."

[0007] If metal is exposed on the inner surface of the second through hole, there is a possibility that discharge may occur via the path through the first through hole.For this reason, the second through hole is often formed so as to penetrate an insulating member fixed to the base plate.

[0008] In order to prevent discharge, it is preferable that the outer shape of the insulating member when viewed from above is large. However, if the outer shape of the insulating member is made too large, the routing of the coolant flow path inside the base plate is restricted.

[0009] 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 increase the degree of freedom in routing a coolant flow path while preventing discharge. [Means for solving the problem]

[0010] 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 placed and having a first through hole formed therein perpendicular to the mounting surface, a base plate joined to the dielectric substrate and having a coolant flow path formed therein through which a coolant passes, and an insulating member fixed to the base plate, the insulating member having a second through hole perpendicular to the mounting surface and connected to the first through hole. The insulating member has a first portion including an end portion on the dielectric substrate side and a second portion adjacent to the first portion in a direction perpendicular to the mounting surface. When viewed in a direction perpendicular to the mounting surface, the outer shape of the first portion of this electrostatic chuck is larger than that of the second portion.

[0011] In an electrostatic chuck having such a configuration, by enlarging the outer shape of the first portion of the insulating member, a large distance can be secured between the metal portion of the surface of the base plate facing the dielectric substrate and the first through hole, thereby making it possible to sufficiently prevent discharge through the path through the first through hole.

[0012] On the other hand, the outer diameter of the second portion of the insulating member is smaller than the outer diameter of the first portion. This prevents the layout of the refrigerant flow path from being significantly restricted by the placement of the insulating member, thereby increasing the degree of freedom in layout of the refrigerant flow path compared to conventional designs. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide an electrostatic chuck that can increase the degree of freedom in routing the coolant flow path while preventing discharge. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view schematically illustrating a configuration of an electrostatic chuck according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged view of a portion of the configuration of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] 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.

[0016] 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 is, for example, a silicon wafer. The electrostatic chuck 10 may also be used in apparatuses other than semiconductor manufacturing apparatuses.

[0017] 1 is a schematic cross-sectional view showing the configuration of an electrostatic chuck 10 in a state where the electrostatic chuck 10 attracts and holds a substrate W. The electrostatic chuck 10 includes a dielectric substrate 100 and a base plate 200.

[0018] The dielectric substrate 100 is a substantially disk-shaped member made of a sintered ceramic body. The dielectric substrate 100 contains, for example, high-purity aluminum oxide (Al2O3), but may also contain other materials. The purity, type, and additives of the ceramics in the dielectric substrate 100 can be appropriately set in consideration of the plasma resistance and other properties required of the dielectric substrate 100 in semiconductor manufacturing equipment.

[0019] 1 of the dielectric substrate 100 is a "mounting surface" on which the substrate W is placed. Also, a lower surface 120 of the dielectric substrate 100 in FIG. 1 is a "bonded surface" that is bonded to the base plate 200 via a bonding layer 300 described later. 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."

[0020] An attraction electrode 130 is embedded inside the dielectric substrate 100. The attraction electrode 130 is a thin, flat layer made of a metal material such as tungsten, and is disposed parallel to the surface 110. In addition to tungsten, the attraction electrode 130 may be made of molybdenum, platinum, palladium, or the like. When a voltage is applied to the attraction 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 attracting and holding the substrate W. As in this embodiment, only one attraction electrode 130 may be provided as a so-called "monopolar" electrode, or two may be provided as so-called "bipolar" electrodes.

[0021] 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, an inert gas for temperature adjustment is supplied to the space SP from the outside via a through-hole 140 described below. By providing the inert 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. In this embodiment, helium gas is used as the inert gas for temperature adjustment supplied to the space SP, but a gas other than helium gas may also be used.

[0022] A seal ring 111 and dots 112 are provided on a surface 110 that is a mounting surface, and the space SP is formed around these.

[0023] The seal ring 111 is a wall that divides the space SP at the outermost position. The upper end of the seal ring 111 forms part of the surface 110 and abuts against the substrate W. Note that multiple seal rings 111 may be provided to divide the space SP. With this configuration, it is possible to individually adjust the pressure of the helium gas in each space SP and make the surface temperature distribution of the substrate W during processing more uniform.

[0024] The portion marked with the reference numeral "116" in FIG. 1 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. The bottom surface 116 is parallel to the surface 110.

[0025] 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.

[0026] A through hole 140 is formed in the dielectric substrate 100. The through hole 140 is a circular through hole formed to extend in a direction perpendicular to the surface 110, which is the mounting surface. The end of the through hole 140 on the surface 110 side is connected to the space SP. The through hole 140, together with a through hole 440 described later, forms part of a flow path for supplying helium gas toward the space SP. A plurality of through holes 140 are formed in the dielectric substrate 100, but only one of them is shown in FIG. 1. The through hole 140 corresponds to the "first through hole" in this embodiment.

[0027] In this embodiment, the inner diameter of through-hole 140 is constant from the end on the surface 110 side to the end on the surface 120 side. Alternatively, the inner diameter may be enlarged in a portion of through-hole 140. Furthermore, a porous member for preventing discharge may be disposed in that portion of through-hole 140.

[0028] 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. The base plate 200 is bonded to the surface 120 of the dielectric substrate 100 via a bonding layer 300. The surface 210 of the base plate 200, which is on the upper side in FIG. 1, is the "bonded surface" that is bonded to the dielectric substrate 100.

[0029] The bonding layer 300 is a layer provided between the dielectric substrate 100 and the base plate 200, and bonds them together. The bonding layer 300 is formed by curing an adhesive made of an insulating material. In this embodiment, a silicone adhesive is used as the adhesive. However, the bonding layer 300 may be formed by curing another type of adhesive. In either case, it is preferable to use a material with as high a thermal conductivity as possible as the material for the bonding layer 300 so as to reduce the thermal resistance between the dielectric substrate 100 and the base plate 200.

[0030] An insulating film may be formed on the surface of the base plate 200. For example, an alumina film formed by thermal spraying can be used as the insulating film. By covering the surface of the base plate 200 with an insulating film, the dielectric strength of the base plate 200 can be increased.

[0031] A coolant flow path 250 for passing a coolant is formed inside the base plate 200. When a process such as etching is performed in the semiconductor manufacturing equipment, a coolant is supplied to the coolant flow path 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. The coolant is supplied to and discharged from the coolant flow path 250 through an opening (not shown) formed in a surface 220 of the base plate 200 opposite to the surface 210.

[0032] An insulating member 400 is fixed to the base plate 200. The insulating member 400 is a substantially cylindrical member made of an insulating material, and penetrates the base plate 200 from the surface 210 to the surface 220. The insulating member 400 may be made of alumina, for example. There are multiple insulating members 400, and each is provided at a position that overlaps with a through-hole 140 when viewed from above, but only one of them is shown in FIG. 1.

[0033] A through hole 440 is formed in the insulating member 400. The through hole 440 is a circular through hole formed to extend in a direction perpendicular to the surface 110 and the surface 210. The central axis of the through hole 440 coincides with the central axis of the through hole 140 in the dielectric substrate 100. Therefore, the through hole 440 is connected to the through hole 140. The through hole 440, together with the through hole 140, forms part of a flow path for supplying helium gas toward the space SP. The through hole 440 corresponds to the "second through hole" in this embodiment.

[0034] 2 shows an enlarged view of the insulating member 400 and the surrounding area. The insulating member 400 has a first portion 410, a second portion 420, and a third portion 430.

[0035] The first portion 410 is a portion of the insulating member 400 that includes the end portion on the dielectric substrate 100 side. The first portion 410 is substantially cylindrical in shape, and its central axis coincides with the central axis of the through hole 440. The outer diameter D1 of the first portion 410 is larger than the outer diameter D2 of the second portion 420, which will be described next. Therefore, the outer shape of the first portion 410 in top view is larger than the outer shape of the second portion 420 in top view.

[0036] A recess 261 for embedding the first portion 410 is formed in the base plate 200. The first portion 410 is fixed to the recess 261 by, for example, press-fitting or bonding. The portion of the through hole 440 formed in the first portion 410 is also referred to as the "through hole 441" below. The inner diameter D11 of the through hole 441 is equal to the inner diameter of the through hole 140. In this embodiment, the first portion 410 is configured as a separate member from the other portions of the insulating member 400 (the second portion 420 and the third portion 430 described next).

[0037] The second portion 420 is a portion of the insulating member 400 that is adjacent to the first portion 410 in a direction perpendicular to the surface 110. The second portion 420 has a substantially cylindrical shape, and its central axis coincides with the central axis of the through hole 440. As described above, the outer diameter D2 of the second portion 420 is smaller than the outer diameter D1 of the first portion 410.

[0038] A through hole 262 for embedding the second portion 420 is formed in the base plate 200. The portion of the through hole 440 formed in the second portion 420 is also referred to as the "through hole 442" below. The inner diameter D12 of the through hole 442 is larger than the inner diameter D11 of the through hole 441. In other words, the inner diameter D11 of the through hole 440 in the first portion 410 is smaller than the inner diameter D12 of the through hole 440 in the second portion 420. As described above, the first portion 410 and the second portion 420 are configured as separate members. The end of the second portion 420 on the first portion 410 side abuts against the first portion 410.

[0039] The third portion 430 is a portion of the insulating member 400 that includes the end portion on the opposite side from the dielectric substrate 100. The third portion 430 is substantially cylindrical in shape, and its central axis coincides with the central axis of the through hole 440. The outer diameter D3 of the third portion 430 is smaller than the outer diameter D1 of the first portion 410 but larger than the outer diameter D2 of the second portion 420. Therefore, the outer shape of the third portion 430 in a top view is larger than the outer shape of the second portion 420 in a top view.

[0040] A recess 263 for embedding the third portion 430 is formed in the base plate 200. In this embodiment, the second portion 420 and the third portion 430 are configured as an integrated member. The member made up of the second portion 420 and the third portion 430 is fixed to the through hole 262 and the recess 263 by, for example, press-fitting or adhesive. The through hole 442 that passes through the second portion 420 also passes through the third portion 430 while maintaining the same inner diameter.

[0041] When a substrate W is being processed in a semiconductor manufacturing apparatus, the potential difference between the substrate W and the base plate 200 becomes relatively large. If metal is exposed on the inner surface of the through-hole formed in the base plate 200, there is a possibility that an electric discharge will occur between the substrate W and the metal portion through the through-hole 140. The insulating member 400 is provided as a member for preventing such an electric discharge.

[0042] Even in a configuration in which the inner surface of the through hole of base plate 200 is covered with insulating member 400, if the outer diameter of insulating member 400 is relatively small, there is a possibility that discharge may occur along a path such as that shown by arrow AR in Fig. 2. In other words, there is a possibility that discharge may occur along a path that extends from the inner surface of through hole 140 or through hole 440, along the interface between insulating member 400 and bonding layer 300, to surface 210 of base plate 200.

[0043] Therefore, in this embodiment, the outer diameter D1 of the first portion 410 of the insulating member 400 is increased to ensure a large distance between the metal portion of the surface 210 of the base plate 200 facing the dielectric substrate and the through-hole 140. With this configuration, the path along the arrow AR in Fig. 2 is lengthened, and discharge along this path can be sufficiently prevented.

[0044] As a configuration for preventing the above-described discharge, it is conceivable to form the entire insulating member 400 into a cylindrical shape having a large outer diameter D1, the same as that of the first portion 410. However, if the outer diameter of the entire insulating member 400 is made too large, the routing of the coolant flow path 250 inside the base plate 200 will be restricted.

[0045] In contrast to this, in the present embodiment, the outer shape of the second portion 420 of the insulating member 400 is smaller than the outer shape of the first portion 410. The second portion 420 is a portion of the insulating member 400 that is provided at a height position adjacent to the refrigerant flow path 250. With this configuration, the routing of the refrigerant flow path 250 is prevented from being significantly restricted by the arrangement of the insulating member 400, and therefore the degree of freedom in routing the refrigerant flow path 250 is increased compared to conventional configurations.

[0046] In order to achieve the above-described effects, it is preferable that refrigerant flow path 250 be disposed between first portion 410 and third portion 430 in a direction perpendicular to surface 110. That is, in Figures 1 and 2, it is preferable that the upper end of second portion 420 is located further above the upper end of refrigerant flow path 250, and the lower end of second portion 420 is located further below the lower end of refrigerant flow path 250.

[0047] In the insulating member 400 of this embodiment, the first portion 410 and the other portions are configured as separate members. By dividing the insulating member 400 into two parts in this manner, during manufacturing of the electrostatic chuck 10, it becomes possible to insert the first portion 410 into the recess 263 from the surface 210 side, and insert the second portion 420 and the third portion 430 into the recess 263 or the like from the surface 220 side. It is also possible to use different materials for the first portion 410 and the other portions of the insulating member 400. For example, a material suitable for preventing discharge can be used as the material for the first portion 410, and a material suitable for reducing weight and cost can be used as the material for the second portion 420, etc.

[0048] The number of members constituting the insulating member 400 may be two as in this embodiment, but may also be one, or three or more.

[0049] The insulating member 400 does not necessarily have to have the third portion 430. That is, the entire portion of the insulating member 400 closer to the surface 220 than the first portion 410 may have a cylindrical shape with an outer diameter D3. However, if the third portion 430 is provided as in the present embodiment, when the second portion 420 and the third portion 430 are inserted into the recess 263 or the like from the surface 220 side during manufacturing of the electrostatic chuck 10, the third portion 430 will abut against the portion indicated by the symbol "A" in FIG. 2 . This prevents the second portion 420 or the like from being inserted too deeply, which would otherwise result in a large force being applied to the first portion 410.

[0050] 2, the inner diameter D12 of the through hole 442 provided in the first portion 410 is larger than the inner diameter D11 of the through hole 441 provided in the second portion 420, etc. This prevents a change in the flow resistance of the helium gas even if the central axes of the two through holes are misaligned.

[0051] The outer shape of the cross section of insulating member 400 cut along a plane parallel to surface 110 may be a shape other than a circle. Even in this case, it is sufficient that the outer shape of first portion 410 in top view is larger than the outer shape of second portion 420 in top view.

[0052] The above describes an example in which the through-hole 400 formed in the insulating member 400 is provided as part of a gas hole for supplying an inert gas to the space SP. The through-hole 400 formed in the insulating member 400 may be formed as a hole for inserting a lift pin (not shown) provided in a semiconductor manufacturing apparatus.

[0053] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise. [Explanation of symbols]

[0054] 10: Electrostatic chuck 100: Dielectric substrate 110: Face 140:Through hole 200: Base plate 250: Refrigerant flow path 400: Insulating material 410: Part 1 420:Second part 430: 3rd part 440:Through hole W: Substrate

Claims

1. a dielectric substrate having a mounting surface on which an object to be attached is placed and having a first through hole formed therein and perpendicular to the mounting surface; a base plate joined to the dielectric substrate and having a coolant flow path formed therein through which a coolant passes; an insulating member fixed to the base plate, the insulating member having a second through hole perpendicular to the mounting surface and connected to the first through hole; The insulating member is a first portion including an end portion on the dielectric substrate side; a second portion adjacent to the first portion in a direction perpendicular to the placement surface, When viewed from a direction perpendicular to the placement surface, An electrostatic chuck, wherein the outer shape of the first portion is larger than the outer shape of the second portion.

2. 2. The electrostatic chuck according to claim 1, wherein the first portion and the second portion are configured as separate members.

3. the insulating member further has a third portion that includes an end portion opposite to the dielectric substrate, When viewed from a direction perpendicular to the placement surface, the third portion has a larger outer shape than the second portion, 3. The electrostatic chuck according to claim 2, wherein said second portion and said third portion are configured as an integral member.

4. 3. The electrostatic chuck according to claim 2, wherein an inner diameter of the second through hole in the first portion is smaller than an inner diameter of the second through hole in the second portion.

Images