Electrostatic chuck

Abstract

An electrostatic chuck is provided that can easily separate annular members. The electrostatic chuck (10) comprises a first part (101) including a surface (110) on which a substrate (W) is loaded, and a second part (102) that protrudes further outward from the outer edge of the first part (101) and includes a surface (180) on which an annular member (RE) is loaded. A portion of the surface (180) is provided with a rough surface (182) that allows gas from the surroundings to enter between the annular member (RE) and the surface (180) more easily than in other parts of the surface (180).

Description

Technology Field

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

[0002] For example, in a semiconductor manufacturing device such as an etching device, 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 is provided with a dielectric substrate having adsorption electrodes. When voltage is applied to the adsorption electrodes, electrostatic force is generated, and a substrate loaded on the dielectric substrate is adsorbed and held.

[0003] During substrate processing, an annular member, referred to as a focus ring, is disposed around the substrate. For example, as described in Patent Document 1 below, a flange portion for loading such annular member may be provided on the dielectric substrate. The portion of the dielectric substrate where the substrate to be processed, such as a silicon wafer, is loaded is hereinafter also referred to as the "first portion." Furthermore, the above-mentioned flange portion provided on the dielectric substrate is hereinafter also referred to as the "second portion." The second portion (flange portion) protrudes further outward from the outer edge of the first portion. Prior art literature

[0004] Japanese Patent Publication No. 2004-281680 The problem to be solved

[0005] In order to suppress thermal resistance between the annular member and the second part, it is preferable that the surface of the second part be smooth. However, if the entire surface of the second part is made too smooth, there is a possibility that the annular member will adhere to the surface and the annular member cannot be easily removed.

[0006] The present invention has been made in consideration of these problems, and its purpose is to provide an electrostatic chuck capable of easily separating an annular member. means of solving the problem

[0007] To solve the above problem, the electrostatic chuck according to the present invention comprises a first portion including a first loading surface on which an adsorbed object is loaded, and a second portion including a second loading surface on which an annular member is loaded, which protrudes further outward from the outer end of the first portion. A portion of the second loading surface is provided with an escape-promoting portion that facilitates the entry of gas from the surroundings between the annular member and the second loading surface, compared to other portions of the second loading surface.

[0008] When separating the annular member from the second loading surface, surrounding gas smoothly enters the separation promotion part, thereby relieving the close contact between the second loading surface and the annular member. Because of this, the annular member can be easily separated from the second loading surface. Effects of the invention

[0009] According to the present invention, an electrostatic chuck capable of easily separating an annular member can be provided. Brief explanation of the drawing

[0010] FIG. 1 is a cross-sectional view schematically illustrating the configuration of an electrostatic chuck according to a first embodiment. FIG. 2 is a drawing showing an enlarged view of the configuration of a part of an electrostatic chuck according to the first embodiment. FIG. 3 is a drawing showing an enlarged view of a part of the configuration of an electrostatic chuck according to a modified example of the first embodiment. FIG. 4 is a drawing showing an enlarged view of a part of the configuration of an electrostatic chuck according to a second embodiment. Specific details for implementing the invention

[0011] The present embodiment will be described below with reference to the attached drawings. To facilitate understanding of the description, the same reference numerals are assigned to identical components in each drawing as much as possible, and redundant descriptions are omitted.

[0012] A first embodiment is described. The electrostatic chuck (10) according to this embodiment is configured to hold and support a substrate (W) to be processed by electrostatic force within an unillustrated semiconductor manufacturing device, such as an etching device, for example. The substrate (W) to be adsorbed is, for example, a silicon wafer. The electrostatic chuck (10) may be used in a device other than a semiconductor manufacturing device.

[0013] FIG. 1 shows a schematic cross-sectional view of the configuration of an electrostatic chuck (10) in a state of adsorbing and holding a substrate (W). The electrostatic chuck (10) comprises a dielectric substrate (100) and a base plate (200).

[0014] The dielectric substrate (100) is a roughly disc-shaped member made of a ceramic sintered body. The dielectric substrate (100) may include, for example, high-purity aluminum oxide (Al2O3), but may also include other materials. The purity, type, and additives of the ceramics in the dielectric substrate (100) can be appropriately set by considering the plasma resistance required for the dielectric substrate (100) in a semiconductor manufacturing apparatus.

[0015] The upper side surface (110) of the dielectric substrate (100) in FIG. 1 is a “loading surface” on which the substrate (W) is loaded. Additionally, the lower side surface (120) of the dielectric substrate (100) in FIG. 1 is a “bonding surface” that is bonded to the base plate (200) through the bonding layer (300). The viewpoint when looking at the electrostatic chuck (10) from the side of the surface (110) along a direction perpendicular to the surface (110) is hereinafter also referred to as “when viewed from the upper surface.” The surface (110) corresponds to the “first loading surface” in this embodiment.

[0016] The dielectric substrate (100) has a first portion (101) and a second portion (102). The first portion (101) is a roughly cylindrical portion extending from the surface (110) toward the lower side of FIG. 1 to the surface (120). This first portion (101) can be described as a portion of the dielectric substrate (100) that includes the surface (110), which is the first loading surface.

[0017] The second part (102) is an annular part that protrudes further outward from the outer edge of the first part (101) and is also referred to as the "flange part" of the dielectric substrate (100). In FIG. 1, the boundary between the first part (101) and the second part (102) is shown as a dotted line DL. The second part (102) is thinner than the first part (101). That is, the dimensions of the second part (102) in the direction perpendicular to the surface (110) (up and down direction in FIG. 1) are smaller than the dimensions of the first part (101) in the same direction. The surface (120) described above is the lowest side surface of the first part (101) in FIG. 1 and is also the lowest side surface of the second part (102). The uppermost surface (180) of the second part (102) is located lower than the surface (110) in FIG. 1.

[0018] When processing of a substrate (W) in a semiconductor manufacturing apparatus, an annular member (RE), referred to as a focus ring, is arranged around the substrate (W). The surface (180) of the second part (102) is a "loading surface" on which such annular member (RE) is loaded. The surface (180) is a surface parallel to the surface (110). The support from below by the surface (180) may be the entire annular member (RE) as in the example of FIG. 1, but may be only a part of the annular member (RE). The surface (180) corresponds to the "second loading surface" in this embodiment. The second part (102) can be said to be a part of the dielectric substrate (100) that includes the surface (180) which is the second loading surface.

[0019] An adsorption electrode (130) is provided inside the first portion (101) of the dielectric substrate (100). The adsorption electrode (130) is a thin, flat layer formed by a metal material such as tungsten, for example, and is arranged to be parallel to the surface (110). In addition to tungsten, molybdenum, platinum, palladium, etc. may be used as the material for the adsorption electrode (130). When voltage is applied to the adsorption electrode (130) from the outside through a power supply path not shown, an electrostatic force is generated between the surface (110) and the substrate (W), thereby adsorbing and supporting the substrate (W). Various known configurations may be adopted as the configuration of the power supply path. As in this embodiment, the adsorption electrode (130) may be provided as a so-called "single-pole" electrode with only one electrode, but may also be provided as a so-called "double-pole" electrode with two electrodes.

[0020] An internal electrode (140) is provided inside the second portion (102) of the dielectric substrate (100). The internal electrode (140) is a thin, flat layer formed of the same material as the adsorption electrode (130) and is arranged to be parallel to the surface (180). When voltage is applied to the internal electrode (140) from the outside through a power supply path not shown, an electrostatic force is generated between the surface (180) and the annular member (RE), thereby adsorbing and supporting the annular member (RE). Various known configurations may be adopted as the configuration of the power supply path connected to the internal electrode (140). The internal electrode (140) may be provided as a single so-called "single-pole" electrode as in the present embodiment, but may also be provided as two so-called "double-pole" electrodes.

[0021] In addition to the adsorption electrode (130) or internal electrode (140) described above, an RF electrode may be provided inside the dielectric substrate (100) to generate plasma and attract it toward the substrate (W). Furthermore, the adsorption electrode (130) or internal electrode (140) may also be used as the RF electrode described above.

[0022] As illustrated in FIG. 1, a space (SP) is formed between the dielectric substrate (100) and the substrate (W). When processing such as etching is performed in a semiconductor manufacturing apparatus, a temperature-regulating helium gas is supplied to the space (SP) from the outside through a gas hole not illustrated. By interposing helium gas between the dielectric substrate (100) and the substrate (W), the thermal resistance between the two is adjusted, thereby maintaining the temperature of the substrate (W) at an appropriate temperature. Additionally, the temperature-regulating gas supplied to the space (SP) may be a type of gas different from helium.

[0023] A seal ring (111) or a dot (112) is provided on the loading surface (110), and the above-mentioned space (SP) is formed around them.

[0024] The seal ring (111) is a wall that partitions the space (SP) at the outermost position. The top of the seal ring (111) is part of the surface (110) and comes into contact with the substrate (W). Additionally, a plurality of seal rings (111) may be provided to divide the space (SP). By configuring it in this way, 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) uniform during processing.

[0025] In FIG. 1, the part labeled “116” is the bottom surface of the space (SP). Hereinafter, this part is also referred to as the “bottom surface (116).” The seal ring (111) is formed as a result of cutting out a part of the surface (110) to the position of the bottom surface (116), together with the dot (112) described below.

[0026] The dot (112) is a circular projection protruding from the bottom surface (116). Multiple dots (112) are provided and are distributed approximately evenly on the loading surface of the dielectric substrate (100). The top of each dot (112) is part of the surface (110) and contacts the substrate (W). By providing multiple such dots (112), bending of the substrate (W) is suppressed.

[0027] The base plate (200) is a roughly disc-shaped member that supports the dielectric substrate (100). The base plate (200) is formed from a metal material, such as aluminum, for example. Among the base plate (200), the upper side surface (210) in FIG. 1 is formed as a "bonded surface" that is bonded to the dielectric substrate (100) via a bonding layer (300). The external shape of the surface (210) when viewed from the upper side is approximately the same as the external shape of the second part (102) when viewed from the upper side.

[0028] 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 a cured adhesive made of an insulating material. In this embodiment, silicone adhesive is used as the adhesive. However, the bonding layer (300) may be a cured adhesive of another type. In any case, in order to reduce the thermal resistance between the dielectric substrate (100) and the base plate (200), it is preferable to use a material with as high a thermal conductivity as possible as the material of the bonding layer (300).

[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 thermal spraying may be used. By covering the surface of the base plate (200) with an insulating film, the dielectric strength of the base plate (200) can be increased.

[0030] A refrigerant passage (240) for passing a refrigerant is formed inside the base plate (200). When processing such as etching is performed in a semiconductor manufacturing apparatus, a refrigerant is supplied from the outside to the refrigerant passage (240), thereby cooling the base plate (200). During processing, heat generated from the substrate (W) is transferred 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 along with the refrigerant. The supply and discharge of the refrigerant to and from the refrigerant passage (240) is carried out through an opening not shown formed on the side (220) opposite to the side (210) of the base plate (200). The refrigerant passage (240) is formed to pass through not only the area overlapping with the first part (101) when viewed from the top surface, but also the area overlapping with the second part (102). For this reason, not only the substrate (W) but also the annular member (RE) is cooled by the refrigerant passing through the refrigerant path (240).

[0031] When processing of a substrate (W) in a semiconductor manufacturing apparatus is being performed, an annular member (RE) is loaded onto a surface (180) as previously described. When processing of the substrate (W) is completed, the annular member (RE) is separated from the surface (180). At this time, if the entire surface (180) is a smooth surface, there is a possibility that the annular member (RE) will adhere to the surface (180) and the annular member (RE) will not be easily detached. Therefore, in the electrostatic chuck according to the present embodiment, the above-mentioned phenomenon is prevented by studying the configuration of the surface (180).

[0032] In FIG. 2, the configuration of the boundary portion (i.e., dotted line DL) or the vicinity thereof between the first portion (101) and the second portion (102) of the electrostatic chuck (10) of FIG. 1 is schematically illustrated. As shown in FIG. 2, the surface shape of the surface (180) is not uniform overall. The surface (180) has a smooth portion (181) and a rough portion (182).

[0033] The smooth portion (181) is the part of the surface (180) excluding the rough portion (182) described below. The smooth portion (181) is formed as a smooth surface in its entirety. By the entire smooth portion (181) being in close contact with the annular member (RE), the thermal resistance between the annular member (RE) and the second portion (102) is reduced. As a result, the cooling of the annular member (RE) can be performed efficiently.

[0034] The roughened portion (182) is a part of the surface (180) near the end of the inner circumference and is adjacent to the smooth portion (181) described above. The surface roughness (e.g., Ra) of the roughened portion (182) is rougher compared to the surface roughness of the smooth portion (181). When viewed from the top surface, the roughened portion (182) is extended in an annular shape to surround the first portion (101) from the outer circumference. When viewed from the top surface, the entire roughened portion (182) may not be connected in an annular shape, and may be interrupted in some parts. The roughened portion (182) described above can be said to be a part of the surface (180) where the surface roughness is locally rough.

[0035] In the roughened portion (182), compared to the smooth portion (181), the gap between the surface (180) and the annular member (RE) is slightly larger, so that surrounding gas (e.g., air) can easily enter the gap. Therefore, when attempting to separate the annular member (RE) from the surface (180), surrounding gas can smoothly enter directly over the roughened portion (182), immediately dissolving the close contact between the surface (180) and the annular member (RE). Because of this, the annular member (RE) can be easily separated from the surface (180). The roughened portion (182) is a part of the surface (180) where surrounding gas can easily enter between it and the annular member (RE) compared to other parts of the surface (180) (i.e., the smooth portion (181)), and corresponds to the "separation promoting portion" in this embodiment.

[0036] The roughened portion (182) can be provided at any location on the surface (180). However, the portion near the inner end of the surface (180) is the portion where the surrounding gas first enters when the annular member (RE) is to be separated. Therefore, as in this embodiment, it is preferable to provide the roughened portion (182) in the portion near the inner end of the surface (180). For the same reason, as in the modified example shown in FIG. 3, the roughened portion (182) may be provided in the portion near the outer end of the surface (180).

[0037] A second embodiment will be described. Hereinafter, the differences from the first embodiment will be mainly described, and the similarities with the first embodiment will be appropriately omitted.

[0038] In FIG. 4, the configuration of the boundary portion (i.e., dotted line DL) or the vicinity thereof between the first portion (101) and the second portion (102) of the electrostatic chuck (10) according to the present embodiment is schematically illustrated as in FIG. 2. The surface (180) of the present embodiment has a smooth portion (181) and a groove portion (183).

[0039] The smooth portion (181) is a part formed as a smooth surface. The area in which the smooth portion (181) is provided and the shape of its surface are all the same as in the first embodiment.

[0040] The groove (183) is a portion of the surface (180) near the end of the inner circumference and is adjacent to the smooth portion (181) described above. In the groove (183), the surface (180) is recessed in a concave shape toward the surface (120) side (downward side in FIG. 4). The groove (183) is a groove that extends in an annular shape to surround the first portion (101) from the outer circumference side when viewed from the top surface. When viewed from the top surface, the entire groove (183) is not connected in an annular shape, and it may be broken in the middle in some parts. The groove (183) described above can be said to be a portion of the surface (180) that is recessed in a concave shape.

[0041] In the groove portion (183), compared to the smooth portion (181), the gap between the surface (180) and the annular member (RE) is larger, so surrounding gas (e.g., air) can easily enter the gap. Therefore, when attempting to separate the annular member (RE) from the surface (180), surrounding gas smoothly enters the inside of the groove portion (183), immediately dissolving the tight contact between the surface (180) and the annular member (RE). Because of this, the annular member (RE) can be easily separated from the surface (180). The groove portion (183) is a part of the surface (180) where surrounding gas can easily enter between it and the annular member (RE) compared to other parts (i.e., the smooth portion (181)), and corresponds to the "separation promoting portion" in this embodiment.

[0042] A groove (183) can also be provided at any location on the surface (180). However, the portion near the inner end of the surface (180) is the portion where surrounding gas first enters when separating the annular member (RE). Therefore, as in this embodiment, it is preferable to provide a groove (183) in the portion near the inner end of the surface (180). For the same reason, a groove (183) may be provided in the portion near the outer end of the surface (180).

[0043] The embodiments described above have been explained with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications appropriately made by a person skilled in the art to these specific examples are also included within the scope of the present disclosure, provided that they possess the features of the present disclosure. Each element and its arrangement, conditions, shape, etc., provided that each of the aforementioned specific examples are not limited to those exemplified and can be appropriately modified. Each element provided by each of the aforementioned specific examples can be appropriately combined as long as no technical contradiction arises. Explanation of the symbols

[0044] 10: Power outage chuck 100: Dielectric substrate 101: Part 1 102: Part 2 110: Face 180: Surface 182: Roasting section 183: Homeboo RE: Circular member W: Substrate

Claims

Claim 1 An electrostatic chuck comprising a first portion including a first loading surface on which an adsorbed object is loaded, and a second portion including a second loading surface on which an annular member is loaded, which protrudes further outward from the outer end of the first portion, and wherein a portion of the second loading surface is provided with a detachment promoting portion that facilitates the entry of gas from the surroundings between the annular member and the second loading surface compared to other portions of the second loading surface, wherein the detachment promoting portion is a portion near the inner end of the second loading surface or a portion near the outer end of the second loading surface, and wherein the detachment promoting portion is a portion of the second loading surface on which the surface roughness is locally rough. Claim 2 delete Claim 3 delete Claim 4 delete

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