Electrostatic chuck

Abstract

To provide an electrostatic chuck which can easily secure electric insulation between the electrostatic chuck and a semiconductor manufacturing device.SOLUTION: An electrostatic chuck 10 includes: a dielectric substrate 100; a base plate 200 as a member formed by metal, the base plate being joined to a surface 120 of the dielectric surface 100, located on the side opposite to the side on which a mounting surface is formed; and a supporting plate 400 as a member formed by an insulating material, the supporting plate 400 covering a surface 220 of the base plate 200, located on the side opposite to the side on which the dielectric substrate 100 is formed. In the top view, the supporting plate 400 is provided with a protruding part 430 protruding outward beyond the base plate 200.SELECTED DRAWING: Figure 1

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. As described in Patent Document 1 below, the part of the base plate is attached and fixed to the semiconductor manufacturing apparatus among the electrostatic chucks.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] During the processing of the substrate, due to the incidence of plasma or the like, a part of the substrate or the electrostatic chuck becomes a high potential. Therefore, when attaching the electrostatic chuck to the semiconductor manufacturing apparatus, it is necessary to ensure electrical insulation between the semiconductor device and the electrostatic chuck.

[0005] When attaching the electrostatic chuck to the semiconductor manufacturing apparatus, it is common to fasten and fix a part of the base plate to the semiconductor manufacturing apparatus. For this reason, in the conventional configuration, in order to ensure electrical insulation between the two, for example, it was necessary to make a device on the semiconductor manufacturing apparatus side, such as using an insulating material for the part of the semiconductor manufacturing apparatus that supports the electrostatic chuck or fastening members (bolts, etc.).

[0006] The present invention has been made in view of such problems, and an object thereof is to provide an electrostatic chuck capable of easily ensuring electrical insulation with a semiconductor manufacturing apparatus.

Means for Solving the Problems

[0007] 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 adsorbed is placed, a member formed of metal, which is joined to the surface of the dielectric substrate opposite to the mounting surface, a base plate, and a member formed of an insulating material, which is a support plate covering the surface of the base plate opposite to the dielectric substrate. When viewed from a direction perpendicular to the mounting surface, the support plate is provided with a protruding portion that protrudes outward from the base plate.

[0008] The electrostatic chuck having such a configuration can be attached to the semiconductor manufacturing apparatus with the support plate made of an insulating material in contact with the semiconductor manufacturing apparatus, instead of bringing the base plate made of metal into contact with the semiconductor manufacturing apparatus. Since the support plate is provided with a protruding portion, for example, by providing a clamp mechanism in the semiconductor manufacturing apparatus and sandwiching the protruding portion by the clamp mechanism, the electrostatic chuck can be fixed to the semiconductor manufacturing apparatus. Since it is not necessary to provide, for example, fastening holes in the support plate that reach the base plate, electrical insulation between the semiconductor manufacturing apparatus and the base plate can be easily and surely ensured.

Effects of the Invention

[0009] According to the present invention, it is possible to provide an electrostatic chuck capable of easily ensuring electrical insulation with a semiconductor manufacturing apparatus.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Embodiment for Carrying Out the Invention

[0011] Hereinafter, this embodiment will be described with reference to the accompanying drawings. For ease of understanding of the description, the same components in each drawing are denoted by the same reference numerals 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 shows a schematic 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, a base plate 200, and a support plate 400.

[0014] The dielectric substrate 100 is a substantially disk-shaped member made of a ceramic sintered body. The dielectric substrate 100 is, for example, high-purity aluminum oxide (Al 2 O 3 ) 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, etc. 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 "mounting 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. Along the direction perpendicular to the surface 110, the viewpoint when viewing 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-like layer formed of a metal material such as tungsten, for example, and is arranged 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 a power supply path (not shown), an electrostatic force is generated between the surface 110 and the substrate W, and thereby the substrate W is adsorbed and held. As the configuration of the above power supply path, various known configurations can be adopted. The adsorption electrode 130 may be provided only one as a so-called "single-pole" electrode as in this embodiment, or may be provided two as a so-called "bipolar" electrode.

[0017] 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 different type of gas from helium.

[0018] A seal ring 111 and dots 112 are provided on the surface 110 which is the mounting surface, and the above space SP is formed around these.

[0019] The seal ring 111 is a wall that partitions the space SP at the outermost peripheral position. The upper end of the seal ring 111 forms a part of the surface 110 and abuts against the substrate W. Incidentally, a plurality of seal rings 111 may be provided so as to divide the space SP. With such a configuration, it becomes possible to individually adjust the pressure of the helium gas in each space SP and to make the surface temperature distribution of the substrate W during processing closer to uniform.

[0020] In FIG. 1, the portion marked with the reference numeral "116" is the bottom surface of the space SP. Hereinafter, this portion will also be referred to as the "bottom surface 116". The seal ring 111 is formed as a result of digging down a part of the surface 110 to the position of the bottom surface 116 together with the dot 112 described below.

[0021] 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 and dispersedly on the mounting surface of the dielectric substrate 100. The upper end of each dot 112 forms a part of the surface 110 and abuts against the substrate W. By providing a plurality of such dots 112, the deflection of the substrate W is suppressed.

[0022] 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 on the side opposite to the surface 110 (mounting surface) via the 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.

[0023] The bonding layer 300 is a layer provided between the dielectric substrate 100 and the base plate 200, and bonds the two. The bonding layer 300 is formed by curing an adhesive made of an insulating material. In the present embodiment, a silicone adhesive is used as the adhesive. However, the bonding layer 300 may be formed by curing other types of adhesives. In any case, as the material of the bonding 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.

[0024] 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 thermal 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.

[0025] 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.

[0026] The support plate 400 is a substantially disk-shaped member formed of an insulating material. As the material of the support plate 400, for example, alumina can be used. The support plate 400 is fixed to the base plate 200 in a state of covering the surface 220 of the base plate 200 opposite to the dielectric substrate 100. The support plate 400 may be fixed to the base plate 200 by, for example, adhesion, or may be fastened and fixed using bolts or the like (not shown).

[0027] As shown in FIG. 1, the support plate 400 has a first portion 410 and a second portion 420, and the whole of these forms an integral member. The first portion 410 is the portion of the support plate 400 on the side of the base plate 200. The second portion 420 is the portion of the support plate 400 on the side opposite to the base plate 200. In other words, the second portion 420 is the portion of the support plate 400 excluding the first portion 410. In FIG. 1, the boundary between the first portion 410 and the second portion 420 is indicated by a dotted line DL.

[0028] In the present embodiment, both the first portion 410 and the second portion 420 are substantially disk-shaped portions, and their central axes coincide with each other. The outer diameter of the first portion 410 in a top view is equal to the outer diameter of the surface 220 of the base plate 200. The outer diameter of the second portion 420 in a top view is larger than the outer diameter of the first portion 410 in a top view. For this reason, in a top view, a part of the second portion 420 protrudes outward beyond the first portion 410 and the base plate 200. Thus, the portion of the support plate 400 that protrudes outward beyond the base plate 200 in a top view is hereinafter also referred to as the "protruding portion 430". The protruding portion 430 of the present embodiment protrudes from the outer peripheral end of the base plate 200 over the entire circumference in a top view.

[0029] The surface 401 of the first portion 410 on the side of the base plate 200 is entirely in contact with the surface 220 of the base plate 200 and covers the base plate 200 from the lower side in FIG. 1.

[0030] The surface 402 of the second portion 420 on the side opposite to the base plate 200 is the surface to be installed at a predetermined position in the semiconductor manufacturing apparatus. The electrostatic chuck 10 is fixed to the semiconductor manufacturing apparatus via the support plate 400 with the surface 402 of the support plate 400 in contact with the semiconductor manufacturing apparatus.

[0031] FIG. 2 schematically shows the configuration of the support plate 400 in a top view. The support plate 400 is formed with, for example, holes for supplying refrigerant that communicate with the refrigerant flow path 250, holes for supplying gas that communicate with the space SP, and holes for inserting lift pins. However, in FIGS. 1 and 2, illustration of these holes is omitted.

[0032] In the protruding portion 430, a concave portion 431 is formed so as to recede from the surface on the dielectric substrate 100 side (the upper surface in FIG. 1) toward the surface 402 side. As shown in FIG. 2, a plurality of concave portions 431 are formed in the protruding portion 430 and are arranged at equal intervals along the circumferential direction.

[0033] The support plate 400 having the above-described configuration is a member that is fixed in advance to the base plate 200 before the electrostatic chuck 10 is attached to the semiconductor manufacturing apparatus and becomes a part of the electrostatic chuck 10.

[0034] During the processing of the substrate W, a part of the substrate W and the electrostatic chuck 10 becomes a high potential due to the incidence of plasma or the like. Therefore, when attaching the electrostatic chuck 10 to the semiconductor manufacturing apparatus, it is necessary to ensure electrical insulation between the semiconductor apparatus and the electrostatic chuck 10.

[0035] In the conventional configuration, when attaching an electrostatic chuck to a semiconductor manufacturing apparatus, it was common to fasten and fix a part of the base plate to the semiconductor manufacturing apparatus. Therefore, in order to ensure electrical insulation between the semiconductor manufacturing apparatus and the base plate, for example, it was necessary to make a device on the semiconductor manufacturing apparatus side, such as using an insulating material for a portion (support base) of the semiconductor manufacturing apparatus that supports the electrostatic chuck and fastening members (bolts, etc.). As a result, there were problems such as complication of the configuration on the semiconductor manufacturing apparatus side and complication of the attachment work of the electrostatic chuck.

[0036] Therefore, the electrostatic chuck 10 according to this embodiment is configured to include a support plate 400 that covers the surface 220 of the base plate 200. The electrostatic chuck 10 having such a configuration can be attached to the semiconductor manufacturing apparatus with the support plate 400 made of an insulating material being in contact with the semiconductor manufacturing apparatus, instead of bringing the base plate 200 made of metal into contact with the semiconductor manufacturing apparatus.

[0037] Since the support plate 400 is provided with the protruding portions 430, for example, a clamping mechanism can be provided in the semiconductor manufacturing apparatus, and the electrostatic chuck 10 can be fixed to the semiconductor manufacturing apparatus by sandwiching the protruding portions 430 with the clamping mechanism. Since it is not necessary to provide fastening holes in the support plate 400 that reach, for example, the base plate 200, electrical insulation between the semiconductor manufacturing apparatus and the base plate 200 can be easily and surely ensured.

[0038] Each recess 431 provided in the protruding portion 430 is provided at a position corresponding to the clamping mechanism. The clamping mechanism enters, for example, from the upper side in FIG. 1 into the inside of each recess 431 and sandwiches the protruding portion 430. Therefore, the electrostatic chuck 10 is restricted in its vertical movement in FIG. 1 by the clamping mechanism, and its rotational movement around the central axis is also restricted by the clamping mechanism. In this way, by providing the recesses 431 in the protruding portion 430, it is possible to prevent the electrostatic chuck 10 from being displaced in the rotational direction. Further, for example, by adjusting the number and position of the recesses 431, it is also possible to prevent the electrostatic chuck 10 from being attached to the semiconductor manufacturing apparatus in the wrong direction (rotational direction).

[0039] The recesses 431 may be formed to recede toward the surface 402 side as in this embodiment, or may be formed to recede, for example, from the surface 402 toward the surface 401 side. Further, the recesses 431 may be formed to recede from the outer peripheral side surface of the protruding portion 430 toward the center side.

[0040] The protruding portion 430 of the present embodiment is formed only on the second portion 420 of the support plate 400 and not on the first portion 410. As a result, the overall thickness of the support plate 400 and the thickness of the protruding portion 430 are different from each other. With such a configuration, while ensuring that the overall thickness of the support plate 400 is sufficient for electrical insulation, the thickness of the protruding portion 430 can be set to the thickness required for attachment to the semiconductor manufacturing apparatus. That is, each thickness can be set independently of each other according to its function. In the present embodiment, the thickness T2 of the second portion 420 (i.e., the thickness of the protruding portion 430) is smaller than the thickness T1 of the first portion 410.

[0041] In the present embodiment, the overall thickness T3 (= T1 + T2) of the support plate 400 is smaller than the overall thickness T4 of the base plate 200. In this way, it is preferable to set the thickness T3 of the support plate 400 to the minimum thickness required for attachment to the semiconductor manufacturing apparatus and suppress the overall enlargement of the electrostatic chuck 10.

[0042] The support plate 400 may be formed as an integral member as a whole as in the present embodiment, or may be formed by combining a plurality of members. For example, a configuration in which the first portion 410 and the second portion 420 are formed as separate members and are joined or fastened to each other may be adopted.

[0043] FIG. 3 shows the configuration of the support plate 400 according to a modified example of the present embodiment. In this modified example, the second portion 420 has a substantially disc shape with the same diameter as the first portion 410, and three protruding portions 430A are provided so as to protrude from the outer peripheral side of the second portion 420. That is, the protruding portion 430A is not a single portion protruding over the entire circumference from the outer peripheral end of the base plate 200 (the same as the outer peripheral end of the surface 401) in a top view, but is provided as a plurality of portions arranged along the circumferential direction. A concave portion 431 is formed in each protruding portion 430A. Even in such a mode, the same effect as that of the present embodiment can be obtained.

[0044] The above has described the present embodiment while referring to specific examples. However, the present disclosure is not limited to these specific examples. Those obtained by appropriately making design changes by those skilled in the art to these specific examples are also included in the scope of the present disclosure as long as they have the features of the present disclosure. Each element included in each of the above-described specific examples, and its arrangement, conditions, shape, etc. are not limited to those illustrated and can be changed as appropriate. Each element included in each of the above-described specific examples can be appropriately combined as long as no technical contradiction occurs.

Description of Reference Numerals

[0045] 10: Electrostatic chuck 100: Dielectric substrate 110, 120: Surfaces 200: Base plate 220: Surface 400: Support plate 410: First part 420: Second part 430: Protrusion 431: Recess W: Substrate

Claims

1. A dielectric substrate having a placement surface on which an object to be attracted is placed, A member formed of metal, which is a base plate joined to a surface of the dielectric substrate opposite to the placement surface, A member formed of an insulating material, which is a support plate covering a surface of the base plate opposite to the dielectric substrate, and comprising: When viewed from a direction perpendicular to the placement surface, The electrostatic chuck is characterized in that the support plate is provided with a protruding portion protruding outward from the base plate.

2. When viewed from a direction perpendicular to the placement surface, The electrostatic chuck according to claim 1, wherein the protruding portion protrudes over the entire circumference from the outer peripheral end of the base plate.

3. The electrostatic chuck according to claim 1, wherein a plurality of recesses arranged along the circumferential direction are formed in the protruding portion.

4. The support plate, A first portion on the base plate side, A second portion opposite to the base plate, and having: The electrostatic chuck according to claim 1, wherein the protruding portion is formed only in the second portion.

5. The electrostatic chuck according to claim 4, wherein the second portion is thinner than the first portion.

6. The electrostatic chuck according to claim 4, wherein the first portion and the second portion are integrated.

7. The electrostatic chuck according to claim 1, wherein the support plate is thinner than the base plate.

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