Electrostatic chuck

Abstract

To provide an electrostatic chuck which can suppress variations in the in-plane temperature of a substrate when the substrate is being processed.SOLUTION: An electrostatic chuck 10 includes: a dielectric substrate 100; and a base plate 200 joined to the dielectric substrate 100, the base plate including a refrigerant passage 400 for a refrigerant to pass. In a top view, a refrigerant passage 400 includes; a first flow passage 410 formed to extend along a peripheral direction; a second flow passage 420 formed to extent along a peripheral direction, in a position adjacent to the first flow passage 410 along a radial direction; and a connection flow passage 441 connecting the first flow passage 410 and the second flow passage 420 to each other. The connection flow passage 441 forms a reverse direction to the flow of a refrigerant.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] During processing such as etching, it is necessary to maintain the temperature of the substrate at an appropriate temperature. For this reason, as described in Patent Document 1 below, a refrigerant flow path for passing a refrigerant is formed inside the base plate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Low-temperature refrigerant is supplied from the outside to one end of the refrigerant flow path. The heat from the substrate is transmitted to the refrigerant through the dielectric substrate and the base plate. The refrigerant gradually increases its temperature while flowing through the refrigerant flow path and is discharged to the outside from the other end of the refrigerant flow path. Since the temperature of the refrigerant passing through the refrigerant flow path varies depending on the location, there is a possibility that the in-plane temperature distribution of the substrate during processing becomes non-uniform due to the distribution of the refrigerant temperature.

[0006] The present invention has been made in view of such problems, and an object thereof is to provide an electrostatic chuck capable of suppressing variations in the in-plane temperature of a substrate during processing.

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 having a mounting surface on which an object to be adsorbed is placed, and a base plate joined to the dielectric substrate and having a refrigerant flow path through which a refrigerant passes formed therein. When viewed from a direction perpendicular to the mounting surface, the refrigerant flow path includes a first flow path formed to extend along the circumferential direction, a second flow path formed to extend along the circumferential direction at a position adjacent to the first flow path along the radial direction, and a connection flow path connecting between the first flow path and the second flow path. The connection flow path is formed so as to reverse the flow direction of the refrigerant.

[0008] In the electrostatic chuck having such a configuration, the refrigerant flow path passing through one (upstream side) of the first flow path and the second flow path is reversed in its flow direction in the connection flow path and then passes through the other (downstream side) of the first flow path and the second flow path. For this reason, the direction in which the refrigerant passes through the first flow path and the direction in which the refrigerant passes through the second flow path are opposite to each other.

[0009] As a result, the gradients of the refrigerant temperature along the same circumferential direction are opposite to each other between the first flow path and the second flow path. For example, when the refrigerant passes through the first flow path, the connection flow path, and the second flow path in this order, the temperature of the refrigerant decreases in the first flow path and increases in the second flow path as it moves away from the connection flow path. Since the low-temperature portion of the first flow path and the high-temperature portion of the second flow path are adjacent to each other in this way, the temperature difference between the two is offset to some extent within the base plate and is not transmitted to the substrate thereon. As a result, the temperature of the substrate W at each part can be made closer to being uniform.

Effects of the Invention

[0010] According to the present invention, it is possible to provide an electrostatic chuck capable of suppressing variations in the in-plane temperature of a substrate during processing.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0012] Hereinafter, this embodiment will be described with reference to the accompanying drawings. For ease of understanding of the description, the same reference numerals are given to the same components in each drawing as much as possible, and duplicate descriptions are omitted.

[0013] 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.

[0014] FIG. 1 shows, as a schematic cross-sectional view, 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.

[0015] The dielectric substrate 100 is a substantially disk-shaped member made of a ceramic sintered body. The dielectric substrate 100 is made of, 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 required for the dielectric substrate 100 in a semiconductor manufacturing apparatus.

[0016] 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. Along the direction perpendicular to the surface 110, the viewpoint when looking at the electrostatic chuck 10 from the surface 110 side will also be referred to as the "top view" hereinafter.

[0017] 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 "unipolar" electrode as in this embodiment, or may be provided two as a so-called "bipolar" electrode.

[0018] As shown in FIG. 1, a space SP is formed between the dielectric substrate 100 and the substrate W. When processes such as etching are 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.

[0019] A seal ring 111 and dots 112 are provided on the surface 110 which is the placement surface, and the above space SP is formed around these.

[0020] 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 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.

[0021] 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 dots 112 described below.

[0022] 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 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.

[0023] 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. Of 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 via the joining layer 300.

[0024] 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 above 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.

[0025] 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.

[0026] The base plate 200 has a flange portion 201 that protrudes outward from the surface 110 (mounting surface) and the bonding layer 300 in a top view.

[0027] Inside the base plate 200, a refrigerant flow path 400 for passing refrigerant is formed. When a process such as etching is performed in the semiconductor manufacturing apparatus, refrigerant is supplied from the outside to the refrigerant flow path 400, 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. The supply and discharge of the refrigerant to and from the refrigerant flow path 400 are performed through openings 251 and 252 (not shown in FIG. 1, see FIG. 2) formed on the surface 220 of the base plate 200 opposite to the surface 210. The refrigerant flow path 400 is formed so as to pass not only through the range overlapping the surface 110 in a top view but also through the flange portion 201.

[0028] The configuration of the refrigerant flow path 400 will be described mainly with reference to FIG. 2. FIG. 2 schematically depicts, in a top view, the configuration of the refrigerant flow path 400 formed inside the base plate 200. As described above, openings 251 and 252 are provided in the surface 220 of the base plate 200. The refrigerant flow path 400 connects between the opening 251 and the opening 252 and is formed along a path that passes through substantially the entire base plate 200 in a top view. Both the openings 251 and 252 are circular openings in a top view and are formed so as to extend perpendicularly to the surface 220 from the surface 220 toward the refrigerant flow path 400. The internal spaces of the openings 251 and 252 can also be regarded as part of the refrigerant flow path 400. In the present embodiment, refrigerant is supplied from the outside to the opening 251. The refrigerant that has passed through the refrigerant flow path 400 and is used for cooling the substrate W is discharged to the outside from the opening 252. The opening 251 corresponds to the "first opening" in the present embodiment. The opening 252 corresponds to the "second opening" in the present embodiment.

[0029] The refrigerant flow path 400 includes a first flow path 410, a second flow path 420, a connection flow path 441, a flow path 425, and a central connection flow path 442.

[0030] The first flow path 410 is the portion of the refrigerant flow path 400 closest to the opening 251 and is formed so as to extend in an arc shape along the circumferential direction from the opening 251. The first flow path 410 of the present embodiment is formed over an angular range of nearly 360 degrees at a position near the outer peripheral end portion of the base plate 200. The first flow path 410 is the portion of the refrigerant flow path 400 formed on the outermost peripheral side, and there is no refrigerant flow path 400 on the outer peripheral side of the first flow path 410. As shown in FIG. 1, the first flow path 410 is formed inside the flange portion 201 of the base plate 200. That is, the entire first flow path 410 is formed at a position outside the surface 110 (mounting surface) in a top view.

[0031] The second flow path 420 is a flow path arranged at a position adjacent to the first flow path 410 along the radial direction, that is, at a position one inside the first flow path 410, and is formed to extend in an arc shape along the circumferential direction in the same manner as the first flow path 410. The first flow path 410 and the second flow path 420 are connected via a connecting flow path 441. The entire second flow path 420 is formed at a position overlapping the surface 110 (placement surface) in a top view.

[0032] The connecting flow path 441 is formed so as to reverse the flow direction of the refrigerant. For this reason, although the first flow path 410 and the second flow path 420 extend substantially parallel to each other along the circumferential direction, the flow directions of the refrigerant are opposite to each other. When the opening 251 is the inlet of the refrigerant as in this embodiment, in the first flow path 410, the refrigerant flows in the counterclockwise direction in FIG. 2, and in the second flow path 420, the refrigerant flows in the clockwise direction in FIG. 2.

[0033] Note that although both the first flow path 410 and the second flow path 420 are formed to extend "along the circumferential direction" as described above, they do not necessarily have to extend in a complete arc shape. For example, for the purpose of avoiding gas holes or lift pin holes (not shown), there may be a portion that is not locally in an arc shape in the middle of the first flow path 410 or the second flow path 420. The same applies to the flow path 425 described later.

[0034] In this embodiment, the second flow path 420 is a spiral flow path and is formed to approach the center of the base plate 200 as it moves away from the connecting flow path 441. Only a part of the second flow path 420 adjacent to the first flow path 410 extends from the connecting flow path 441. The second flow path 420 extends to a position at or near the center of the base plate 200 and is connected to a central connecting flow path 442 (described later) at that position.

[0035] The flow path 425 is a portion of the refrigerant flow path 400 closest to the opening 252, and is formed to extend in an arc shape along the circumferential direction from the opening 252. The flow path 425 is a spiral flow path extending along the circumferential direction, and is a flow path approaching the center of the base plate 200 as it moves away from the opening 252. The flow path 425 extends to a position at or near the center of the base plate 200 and is connected to the central connection flow path 442 at that position. The entire flow path 425 is formed at a position overlapping the surface 110 (placement surface) in a top view.

[0036] The direction in which the refrigerant flows through the flow path 425 (counterclockwise in FIG. 2) is opposite to the direction in which the refrigerant flows through the second flow path 420 (clockwise in FIG. 2). The flow path 425 and the second flow path 420 are connected to each other via the central connection flow path 442 at a position at or near the center of the base plate 200. The central connection flow path 442 is formed to reverse the direction of the refrigerant flow in order to connect between the flow path 425 and the second flow path 420 that extend in opposite directions as described above.

[0037] In the configuration as described above, the refrigerant passing through the refrigerant flow path 400 reaches the opening 252 by passing through the opening 251, the first flow path 410, the connection flow path 441, the second flow path 420, the central connection flow path 442, and the flow path 425 in sequence. The opening 251 can be said to be an opening connected to the end of the first flow path 410 on the side opposite to the connection flow path 441. The opening 252 can be said to be an opening connected to the end of the refrigerant flow path 400 on the side opposite to the opening 251.

[0038] Among the refrigerant flow path 400, the portion connecting between the opening 251 and the central connection flow path 442 is hereinafter also referred to as the "first portion 401". The first portion 401 can be said to be a portion approaching the center of the base plate 200 as it moves away from the opening 251. In the present embodiment, it is a portion including the first flow path 410, the connection flow path 441, and the second flow path 420. Note that "approaching the center of the base plate 200 as it moves away from the opening 251" means that the first portion 401 extends generally along the circumferential direction toward the center of the base plate 200 when viewed as a whole. In the middle of the first portion 401, for the purpose of avoiding, for example, gas holes or lift pin holes (not shown), a portion that slightly moves toward the outer peripheral side as it moves away from the opening 251 may locally exist.

[0039] Among the refrigerant flow path 400, the portion connecting between the opening 252 and the central connection flow path 442 is hereinafter also referred to as the "second portion 402". The second portion 402 can be said to be a portion approaching the outer peripheral side of the base plate 200 as it approaches the opening 252. In the present embodiment, it is a portion including the entire flow path 425. Note that "approaching the outer peripheral side of the base plate 200 as it approaches the opening 252" means that the second portion 402 extends generally along the circumferential direction toward the outer periphery of the base plate 200 when viewed as a whole. In the middle of the second portion 402, for the purpose of avoiding, for example, gas holes or lift pin holes (not shown), a portion that slightly moves toward the central side as it approaches the opening 252 may locally exist.

[0040] The reason for configuring the refrigerant flow path 400 as described above will be explained. As described above, low-temperature refrigerant is supplied from the outside to the opening 251 which is one end of the refrigerant flow path 400. The heat from the substrate W is transmitted to the refrigerant through the dielectric substrate 100 and the base plate 200. The refrigerant gradually increases its temperature while flowing through the refrigerant flow path 400 and is discharged to the outside from the opening 252 which is the other end of the refrigerant flow path 400.

[0041] Therefore, for example, when the entire refrigerant flow path 400 has a simple spiral shape from the outer peripheral side toward the center, relatively low-temperature refrigerant cools the outer peripheral side, and relatively high-temperature refrigerant cools the central side. As a result, the temperature of the substrate W becomes higher on the central side. Such a non-uniform in-plane temperature distribution is not preferable in the processing of the substrate W.

[0042] Therefore, in the electrostatic chuck according to the present embodiment, the connection flow path 441 provided between the first flow path 410 and the second flow path 420 is configured to reverse the flow direction of the refrigerant. In such a configuration, the direction in which the refrigerant passes through the first flow path 410 and the direction in which the refrigerant passes through the second flow path 420 are opposite to each other. As a result, the gradients of the refrigerant temperature along the same circumferential direction (for example, the clockwise direction in a top view) are opposite to each other between the first flow path 410 and the second flow path 420.

[0043] For example, when the refrigerant passes through the first flow path 410, the connection flow path 441, and the second flow path 420 in this order as in the present embodiment, the temperature of the refrigerant decreases in the first flow path 410 and increases in the second flow path 420 as the distance from the connection flow path 441 increases. In the present embodiment, since the low-temperature portion of the first flow path 410 and the high-temperature portion of the second flow path 420 are adjacent to each other, the temperature difference between the two is offset to some extent within the base plate 200 and is not transmitted to the substrate W thereon. As a result, it is possible to make the temperature of the substrate W in each part approach evenly. That is, it is possible to suppress the variation in the in-plane temperature of the substrate W during processing.

[0044] The first flow path 410 may be arranged at a position different from the outermost peripheral position among the refrigerant flow paths 400. Also in this case, if a second flow path is formed at a position adjacent to the first flow path 410 along the radial direction and the two are connected by the central connection flow path 442, the same effects as described above can be achieved. However, in view of the fact that the temperature of the substrate W during processing tends to be particularly high at the outermost peripheral portion and the temperature distribution also tends to be non-uniform, it is preferable to arrange the first flow path 410 at the outermost peripheral position as in the present embodiment so that the cooling performance on the outer peripheral side is made uniform along the circumferential direction.

[0045] In addition, in the present embodiment, since the first flow path 410 is formed over an angular range smaller than 360 degrees, the entire first flow path 410 is formed at the outermost peripheral position among the refrigerant flow paths 400. Instead of such an aspect, the first flow path 410 may be formed over an angular range larger than 360 degrees. In this case, a part of the first flow path 410 enters the inner peripheral side (that is, the second round) and is connected to the connection flow path 441 at that position. Thus, only a part, not the entire first flow path 410, may be formed at the outermost peripheral position among the refrigerant flow paths 400. Even in such an aspect, the same effects as described above can be achieved.

[0046] As shown in FIG. 2, in the present embodiment, the flow path width of the first flow path 410 (the dimension along the radial direction, the same applies hereinafter) is smaller than the flow path width of the second flow path 420. As a result, the flow path cross-sectional area of the first flow path 410 is smaller than the flow path cross-sectional area of the second flow path 420. In such a configuration, the flow velocity of the refrigerant passing through the first flow path 410 becomes larger than the flow velocity of the refrigerant passing through the second flow path 420. Thereby, it is possible to enhance the cooling performance of the outer peripheral side portion that tends to become relatively high temperature and further suppress the variation in the in-plane temperature of the substrate W.

[0047] In addition, in the portion downstream from the second flow path 420, the flow path width is constant. Also in the first flow path 410, the flow path width is constant. In the connection flow path 441, the flow path width gradually increases toward the downstream side, smoothly connecting between the first flow path 410 and the second flow path 420.

[0048] Instead of the above-described aspect, an aspect in which the cross-sectional area of the flow path is made different between the first flow path 410 and the second flow path 420 by adjusting the dimension in the depth direction of the flow path instead of the flow path width may be adopted.

[0049] As described above, the first flow path 410 of the present embodiment is formed at a position outside the surface 110 (mounting surface) in a top view, that is, in the flange portion 201 of the base plate 200. The flange portion 201 is a portion where a focus ring (not shown) is installed from above. By arranging the first flow path 410 so as to pass through such a portion, it becomes possible to efficiently and evenly cool the focus ring.

[0050] The refrigerant flow path 400 includes a first portion 401 that approaches the center of the base plate 200 as it moves away from the opening 251, and a second portion 402 that approaches the outer peripheral side of the base plate 200 as it approaches the opening 252. After passing through the first portion 401, the refrigerant reverses its flow direction in the central connection flow path 442 and then passes through the second portion 402 and heads toward the outer peripheral side. In such a configuration, the first portion 401 and the second portion 402 through which the refrigerant flows in opposite directions are adjacent to each other over substantially the entire base plate 200. Thereby, it becomes possible to further suppress the variation in the in-plane temperature of the substrate W.

[0051] As shown in FIG. 2, in the present embodiment, the openings 251 and 252 that are the inlet and outlet of the refrigerant are formed at positions adjacent to each other in a top view without sandwiching a part of the refrigerant flow path 400 therebetween. By forming the openings 251 and 252 at positions close to each other, it becomes possible to easily connect the refrigerant pipes to these in a semiconductor manufacturing apparatus.

[0052] The second embodiment will be described. Hereinafter, the points different from the first embodiment will be mainly described, and the description of the points common to the first embodiment will be omitted as appropriate.

[0053] FIG. 3 schematically depicts, in a top view, the configuration of the refrigerant flow path 400 formed inside the base plate 200 of the present embodiment. Similar to the first embodiment (FIG. 2), in the present embodiment as well, Openings 251 and 252 are formed in the surface 220 of the base plate 200, and the refrigerant flow path 400 is formed so as to connect between these openings. Similar to the first embodiment, the opening 251 in the present embodiment is formed at a position near the outer peripheral end portion of the base plate 200. On the other hand, the opening 252 in the present embodiment is formed at a position at or near the center of the base plate 200.

[0054] The refrigerant flow path 400 of the present embodiment includes a first flow path 410, a second flow path 420, a connection flow path 441, a third flow path 430, and an inner connection flow path 443.

[0055] The first flow path 410 is the portion of the refrigerant flow path 400 closest to the opening 251, and is formed to extend in an arc shape along the circumferential direction from the opening 251. The first flow path 410 is formed over an angular range of nearly 360 degrees at a position near the outer peripheral end portion of the base plate 200. The first flow path 410 is the portion of the refrigerant flow path 400 formed on the outermost peripheral side, and there is no refrigerant flow path 400 on the outer peripheral side of the first flow path 410. Similar to the first embodiment, the first flow path 410 is formed at a position outside the surface 110 (mounting surface) in a top view.

[0056] The second flow path 420 is a flow path disposed at a position adjacent to the first flow path 410 along the radial direction, that is, at a position one inside the first flow path 410, and is formed to extend in an arc shape along the circumferential direction similar to the first flow path 410. The first flow path 410 and the second flow path 420 are connected via a connection flow path 441. The entire second flow path 420 is formed at a position overlapping the surface 110 (mounting surface) in a top view.

[0057] The connection flow path 441 is formed so as to reverse the flow direction of the refrigerant. Therefore, although the first flow path 410 and the second flow path 420 extend substantially parallel to each other along the circumferential direction, their refrigerant flow directions are opposite to each other. When the opening 251 serves as the refrigerant inlet as in the present embodiment, in the first flow path 410, the refrigerant flows in the clockwise direction in FIG. 3, and in the second flow path 420, the refrigerant flows in the counterclockwise direction in FIG. 2.

[0058] In the present embodiment, the second flow path 420 is not a spiral flow path and is formed adjacent to the first flow path 410 over an angular range of nearly 360 degrees along the circumferential direction (that is, so as to be only about one turn).

[0059] The third flow path 430 is a flow path arranged at a position adjacent to the second flow path 420 along the radial direction, specifically at a position further inside the second flow path 420 (that is, on the side opposite to the first flow path 410), and is formed to extend in an arc shape along the circumferential direction like the second flow path 420 and the like. The second flow path 420 and the third flow path 430 are connected via an inner connection flow path 443. The entire third flow path 430 is formed at a position overlapping the surface 110 (mounting surface) in a top view.

[0060] The inner connection flow path 443 is formed so as to reverse the flow direction of the refrigerant. Therefore, although the second flow path 420 and the third flow path 430 extend substantially parallel to each other along the circumferential direction, their refrigerant flow directions are opposite to each other. When the opening 251 serves as the refrigerant inlet as in the present embodiment, in the second flow path 420, the refrigerant flows in the counterclockwise direction in FIG. 3, and in the third flow path 430, the refrigerant flows in the clockwise direction in FIG. 3.

[0061] Note that although the first flow path 410, the second flow path 420, and the third flow path 430 are all formed to extend "along the circumferential direction" as described above, they do not necessarily have to extend in a complete arc shape. For example, for the purpose of avoiding gas holes and lift pin holes (not shown), there may be a portion that is not locally in an arc shape in the middle of the first flow path 410 and the like.

[0062] In the present embodiment, the third flow path 430 is a spiral flow path and is formed so as to approach the center of the base plate 200 as it moves away from the inner connection flow path 443. Only a part of the third flow path 430 adjacent to the second flow path 420 extends from the inner connection flow path 443. The third flow path 430 extends to a position at or near the center of the base plate 200 and is connected to the opening 252 at that position.

[0063] In the configuration as described above, the refrigerant passing through the refrigerant flow path 400 reaches the opening 252 by passing through the opening 251, the first flow path 410, the connection flow path 441, the second flow path 420, the inner connection flow path 443, and the third flow path 430 in this order. The opening 251 can be said to be an opening connected to the end of the first flow path 410 on the side opposite to the connection flow path 441. The opening 252 can be said to be an opening connected to the end of the refrigerant flow path 400 on the side opposite to the opening 251.

[0064] As described above, in the refrigerant flow path 400 in the present embodiment, the first flow path 410 and the second flow path 420 through which the refrigerant flows in opposite directions are arranged adjacent to each other at the outermost peripheral position of the refrigerant flow path 400. Also, inside that, the second flow path 420 and the third flow path 430 through which the refrigerant flows in opposite directions are arranged adjacent to each other. By forming the refrigerant flow path 400 in this way, the outer peripheral side of the substrate W, which is likely to become relatively high in temperature, can be cooled efficiently and evenly.

[0065] In the present embodiment, the flow path cross-sectional area is uniform throughout the refrigerant flow path 400. Instead of such a mode, similar to the first embodiment, the flow path cross-sectional area of the first flow path 410 may be smaller than the flow path cross-sectional areas of other parts.

[0066] The above has described the present embodiment with reference 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 combined as appropriate as long as no technical contradiction occurs.

Explanation of Reference Numerals

[0067] 10: Electrostatic chuck 100: Dielectric substrate 110: Surface 200: Base plate 251, 252: Opening 400: Refrigerant flow path 401: First part 402: Second part 410: First flow path 420: Second flow path 430: Third flow path 441: Connection flow path 443: Inner connection flow path W: Substrate

Claims

1. A dielectric substrate having a mounting surface on which an object to be adsorbed is placed, and a base plate joined to the dielectric substrate and having a refrigerant flow path through which a refrigerant flows formed therein, characterized in that when viewed from a direction perpendicular to the mounting surface, the refrigerant flow path includes a first flow path formed to extend along the circumferential direction, a second flow path formed to extend along the circumferential direction at a position adjacent to the first flow path along the radial direction, and a connection flow path connecting between the first flow path and the second flow path, wherein the connection flow path is formed so as to reverse the direction of flow of the refrigerant. An electrostatic chuck

2. The electrostatic chuck according to claim 1, characterized in that at least a part of the first flow path is formed at a position on the outermost peripheral side of the refrigerant flow path.

3. When viewed from a direction perpendicular to the mounting surface, the electrostatic chuck according to claim 2, characterized in that the first flow path is formed at a position outside the mounting surface.

4. At an end of the first flow path opposite to the connection flow path, a first opening formed in the base plate is connected, The electrostatic chuck according to claim 2, characterized in that at an end of the refrigerant flow path opposite to the first opening, a second opening formed in the base plate is connected.

5. The refrigerant flow path includes a first portion that approaches the center of the base plate as it moves away from the first opening, and a second portion that approaches the outer peripheral side of the base plate as it approaches the second opening. The electrostatic chuck according to claim 4

6. When viewed from a direction perpendicular to the mounting surface, the electrostatic chuck according to claim 5, characterized in that the first opening and the second opening are formed adjacent to each other without sandwiching the refrigerant flow path therebetween.

7. The electrostatic chuck according to claim 2, characterized in that the flow path cross-sectional area of the first flow path is smaller than the flow path cross-sectional area of the second flow path.

8. When viewed from a direction perpendicular to the mounting surface, the refrigerant flow path further includes a third flow path formed to extend along the circumferential direction at a position adjacent to the second flow path along the radial direction and on the side opposite to the first flow path, and an inner connection flow path connecting between the second flow path and the third flow path. The electrostatic chuck according to claim 2, wherein the inner connection flow path is formed so as to reverse the flow direction of the refrigerant.

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