Base and holding device

Abstract

A technique is provided that can suppress an increase in pressure loss of a refrigerant flowing inside a branch channel in a refrigerant channel that includes a main channel and a branch channel. [Solution] A base having a refrigerant flow path formed therein through which a refrigerant flows, the refrigerant flow path including a branched portion into a main flow path and a tributary flow path having a smaller cross-sectional area in cross section than the main flow path, and a value representing the roughness of the tributary flow path defining surface, which is the surface defining the tributary flow path, is smaller than a value representing the roughness of the main flow path defining surface, which is the surface defining the main flow path.

Description

[Technical Field]

[0001] The present disclosure relates to a base and a holding device. [Background technology]

[0002] Conventionally, a holding device has been known that includes a mounting surface on which an object is placed and a coolant flow path through which a coolant flows. Techniques have been proposed for achieving uniformity in the temperature of a substrate, which is an object, in such a holding device. For example, Patent Document 1 proposes a technique for correcting the temperature distribution of a substrate without changing the basic shape of the flow path by providing a protruding member on a base on which the coolant flow path is formed, thereby locally changing the flow rate of the coolant. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2019-041024 Summary of the Invention [Problem to be solved by the invention]

[0004] A refrigerant flow path may include a branched portion into a main flow path and a branch flow path having a smaller cross-sectional area than the main flow path. Generally, the smaller the cross-sectional area of ​​a flow path, the greater the pressure loss of the fluid flowing inside the flow path. Therefore, a refrigerant flow path including a main flow path and a branch flow path has a problem in that the pressure loss of the refrigerant flowing inside the branch flow path is large. Note that Patent Document 1 does not take into consideration the pressure loss of the refrigerant in a refrigerant flow path including a main flow path and a branch flow path.

[0005] An object of the present disclosure is to provide a technique that can suppress an increase in pressure loss of a refrigerant flowing inside a branch channel in a refrigerant channel that includes a main channel and a branch channel. [Means for solving the problem]

[0006] The present disclosure has been made to solve at least part of the above-mentioned problems, and can be realized in the following forms.

[0007] (1) According to one aspect of the present disclosure, there is provided a base having a refrigerant flow path formed therein through which a refrigerant flows, the refrigerant flow path including a portion branching into a main flow path and a branch flow path having a smaller cross-sectional area than the main flow path, and a value representing the roughness of a branch flow path defining surface that defines the branch flow path is smaller than a value representing the roughness of a main flow path defining surface that defines the main flow path.

[0008] The smaller the cross-sectional area of ​​the flow path, the greater the pressure loss of the fluid flowing inside the flow path. With this configuration, the value representing the roughness of the tributary flow path defining surface is smaller than the value representing the roughness of the main flow path defining surface, so the tributary flow path defining surface is smoother than the main flow path defining surface. This makes it possible to prevent the pressure loss of the refrigerant flowing inside the tributary flow path, which has a smaller cross-sectional area than the main flow path, from increasing.

[0009] (2) In the base of the above embodiment, the value obtained by dividing the value representing the roughness of the main flow path defining surface by the value representing the roughness of the tributary flow path defining surface may be equal to or greater than 1.0 and less than 20.0. With this configuration, the main flow path defining surface is 1.0 to 20.0 times rougher than the tributary flow path defining surface. In other words, because the tributary flow path defining surface is smoother than the main flow path defining surface, it is possible to prevent an increase in pressure loss of the refrigerant flowing inside the tributary flow path, which has a smaller cross-sectional area than the main flow path.

[0010] (3) In the base of the above embodiment, the cross section of the main flow path may be rectangular, and one of the first opposing surfaces of the main flow path defining surface that faces the other in the thickness direction of the base may be rougher than the other first opposing surface. With this configuration, when the coolant flows through the main flow path, turbulence of the coolant is more likely to occur on one of the first opposing surfaces than on the other of the first opposing surfaces. Such turbulent coolant flow increases the cooling efficiency, thereby improving the cooling efficiency on the side of the one of the first opposing surfaces of the base.

[0011] (4) In the base of the above embodiment, the second opposing surfaces of the main flow path defining surfaces that face each other along a direction perpendicular to the thickness direction of the base may each be rougher than the other first opposing surface. With this configuration, when the coolant flows through the main flow path, turbulence of the coolant is likely to occur on both the first opposing surface and the third opposing surface, which further improves the cooling efficiency on the side of the base that faces the first opposing surface.

[0012] (5) In the base of the above embodiment, the cross section of the branch channel is rectangular, Of the tributary flow path defining surfaces, one of the third opposing surfaces that face each other in the thickness direction of the base may be rougher than the other third opposing surface. With this configuration, when the refrigerant flows through the branch passage, turbulence of the refrigerant is more likely to occur on one of the first opposing surfaces than on the other of the third opposing surfaces. Such turbulent refrigerant flow increases the cooling efficiency, thereby improving the cooling efficiency on the side of the base that faces the one of the third opposing surfaces.

[0013] (6) In the base of the above embodiment, the fourth opposing surfaces of the tributary flow path defining surfaces that face each other along a direction perpendicular to the thickness direction of the base may each be rougher than the other third opposing surface. With this configuration, when the refrigerant flows through the branch passage, turbulence of the refrigerant is likely to occur not only on one of the third opposing surfaces but also on the fourth opposing surface, thereby further improving the cooling efficiency on the side of the base that faces the one of the third opposing surfaces.

[0014] (7) In the base of the above form, the cross-section of the main flow path and the cross-section of the tributary flow path may each be rectangular, and the length of the cross-section of the tributary flow path along the thickness direction of the base may be longer than the length of the cross-section of the main flow path along the thickness direction, and the length of the cross-section of the main flow path along a direction perpendicular to the thickness direction of the base may be longer than the length of the cross-section of the tributary flow path along the direction perpendicular to the thickness direction. This configuration also makes it possible to prevent the pressure loss of the refrigerant flowing through the branch passages, which have a smaller cross-sectional area than the main passage, from increasing.

[0015] (8) According to another aspect of the present disclosure, there is provided a holding device. The holding device includes a base according to any one of the above aspects, and a plate-like member having a mounting surface on which an object is placed and supported by the base. With this configuration, since the holding device includes the base according to any one of the above aspects, it is possible to suppress an increase in pressure loss of the refrigerant flowing inside the branch passage.

[0016] The present disclosure can be realized in various forms, for example, in the form of a semiconductor manufacturing apparatus including a holding device, a semiconductor manufacturing system including a holding device, a method for manufacturing a holding device, a method for manufacturing a semiconductor, etc. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a perspective view of a retention device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a first cross-sectional view of a retaining device. [Figure 3] FIG. 10 is a second cross-sectional view of the retaining device. [Figure 4] FIG. 2 is an explanatory diagram of a cross section of a main channel and a cross section of a branch channel. [Figure 5] FIG. [Figure 6] FIG. 2 is an explanatory diagram of a surface defining a main flow path and a surface defining a tributary flow path. [Figure 7] 10A and 10B are explanatory diagrams of other examples of the cross section of the main channel and the cross section of the branch channel. DETAILED DESCRIPTION OF THE INVENTION

[0018] <Embodiment> FIG. 1 is a perspective view of a holding device 1 according to an embodiment of the present disclosure. FIG. 2 is a first cross-sectional view of the holding device 1. The holding device 1 is an electrostatic chuck that attracts and holds a substrate W by electrostatic attraction. That is, the object held by the holding device 1 is the substrate W. The electrostatic chuck is used, for example, as a table on which the substrate W is placed in an etching process using plasma in a chamber equipped with the electrostatic chuck. The holding device 1 includes a base 10, a ceramic substrate 20, and a bonding layer (not shown). In the holding device 1, as shown in FIG. 1, the base 10 and the ceramic substrate 20 are stacked in this order. The holding device 1 positions the substrate W relative to the holding device 1 using a focus ring FR installed around the outer periphery of the ceramic substrate 20. FIGS. 1 and 2 illustrate x, y, and z axes, which are orthogonal to each other. The z axis corresponds to the stacking direction of the base 10 and the ceramic substrate 20, and the x and y axes correspond to directions perpendicular to the z axis. The same applies to the x, y, and z axes illustrated in FIG. 3 and subsequent figures. For convenience of explanation, the size relationships between the base 10, the ceramic base 20, and the focus ring FR in FIGS. 1 and 2 differ from the actual relationships.

[0019] The base 10 is a substantially cylindrical member that serves as the base of the holding device 1. In this embodiment, the base 10 is a sintered body whose main component is silicon carbide (SiC). The main component refers to the component with the highest content. By using silicon carbide, which has high corrosion resistance, as the main component of the base 10, it is possible to use an aqueous refrigerant. Silicon carbide also has high thermal conductivity and can be suitably used as a ceramic substrate for cooling. The thermal conductivity of the base 10 is not particularly limited, but it is preferably formed from ceramics with a thermal conductivity of 70 W / mK or more. Furthermore, silicon carbide is electrically conductive, so it can also serve as an electrode for high-frequency current.

[0020] The material forming the base 10 is not limited to a material containing silicon carbide as a main component. The base 10 may be formed from aluminum (Al), titanium (Ti), molybdenum (Mo), tungsten (W), alloys thereof, SUS, a metal-ceramic composite (MMC) such as an Al-SiC composite, a Ti-SiC composite, or an Al-Ti-SiC composite, or a material containing ceramics as a main component such as aluminum nitride (AlN) or alumina (Al2O3). When the base 10 is formed from a composite of ceramic and metal, the coefficient of thermal expansion (CTE) can be easily adjusted and toughness is improved.

[0021] The thickness of the base 10 is not particularly limited, but is preferably 10 mm to 50 mm. The thickness of the base 10 is more preferably 15 mm to 30 mm. In this specification, when a numerical range is indicated using "to", it is intended to include both the lower limit and the upper limit unless otherwise specified. For example, the expression "10 to 20" includes both the lower limit "10" and the upper limit "20". In other words, "10 to 20" has the same meaning as "10 or more and 20 or less".

[0022] The diameter of the base 10 is not particularly limited, but is set to be equal to or larger than the outer diameter of the object to be held, that is, the substrate W. For example, if the diameter of the substrate W is 300 mm, the diameter of the base 10 will be 300 mm or larger.

[0023] The base 10 has a first base 11 and a second base 12. The first base 11 and the second base 12 are bonded together by a bonding layer (not shown). The first base 11 and the second base 12 may be bonded together by diffusion bonding under high pressure and high temperature, or by using a metal material such as aluminum (Al), indium (In), or an alloy thereof. The base 10 is not limited to a two-layer structure such as the first base 11 and the second base 12, but may be a single-layer structure or a three-layer or more structure.

[0024] The first base 11 is located on the negative side of the base 10 in the z-axis direction. The first base 11 is a plate-like member with a substantially circular planar shape. The first base 11 has a pair of principal surfaces 11a and 11b. The principal surface 11a is a surface of the first base 11 that defines the positive side in the z-axis direction. The principal surface 11b is a surface of the first base 11 that defines the negative side in the z-axis direction.

[0025] The second base 12 is stacked on the first base 11 from the positive side in the z-axis direction. The second base 12 is a substantially circular plate-like member whose planar shape is substantially the same size as that of the first base 11. The second base 12 has a pair of main surfaces 12a and 12b. The main surface 12a is a surface of the second base 12 that defines the positive side in the z-axis direction. The main surface 12b is a surface of the second base 12 that defines the negative side in the z-axis direction. A groove 13 that defines a refrigerant flow path 30 through which a refrigerant flows is formed on the main surface 12b. When the first base 11 and the second base 12 are joined, the main surface 11a (or a joining layer, not shown) of the first base 11 serves as a cover for the groove 13 formed in the second base 12, thereby defining the refrigerant flow path 30. In other words, the refrigerant flow path 30 is formed inside the base 10. The details of the coolant flow path 30 will be described later. Furthermore, the base 10 is formed with a plurality of holes 14 that penetrate the base 10 along the z-axis direction.

[0026] The base 10 can be manufactured by various known manufacturing methods. For example, the base 10 can be manufactured by subjecting a raw material powder to CIP (cold isostatic pressing) to form a compact, and then degreasing, firing, processing, etc.

[0027] Grooves 13 may be formed by machining the molded body before firing, or may be formed by machining after firing. Furthermore, when second base 12 is formed from a conductive material such as silicon carbide, grooves 13 may be formed by electric discharge machining.

[0028] Furthermore, a conductive film may be formed on the surface of the base 10. If the conductivity of the base 10 is insufficient, forming a conductive film on the surface (main surface 12a and side surfaces) of the base 10 allows it to be used as a high-frequency electrode.

[0029] The ceramic substrate 20 is a plate-shaped member laminated on the base 10 from the positive side in the z-axis direction. The ceramic substrate 20 is primarily composed of ceramic. The ceramic substrate 20 and the base 10 are bonded together by a bonding layer (not shown). That is, the ceramic substrate 20 is supported by the base 10. Methods for bonding the base 10 and the ceramic substrate 20 include, but are not limited to, metal bonding, resin bonding, and bonding using inorganic materials. When the material constituting the base 10 is a metal ceramic composite (MMC) with a thermal expansion coefficient close to that of the ceramic material, bonding can be performed using a metal material with high thermal conductivity. The metal material can be aluminum (Al), indium (In), or an alloy thereof. Furthermore, the base 10 and the ceramic substrate 20 may be integrally formed from a single material without a bonding layer. The ceramic substrate 20 is formed from a material primarily composed of aluminum oxide. The ceramic base 20 may be formed of other ceramics such as aluminum nitride, silicon carbide, or yttria (YO). The ceramic base 20 has a pair of principal surfaces 20a and 20b. The principal surface 20a defines the positive side of the ceramic base 20 in the z-axis direction. The principal surface 20b defines the negative side of the ceramic base 20 in the z-axis direction.

[0030] A central portion of the main surface 20a functions as a mounting surface 21 on which the substrate W is mounted. In addition, an outer peripheral portion of the main surface 20a functions as a focus ring mounting surface 22 on which the focus ring FR is mounted. The ceramic base 20 has a plurality of holes 23 formed therein, each of which communicates with the holes 14 formed in the base 10.

[0031] The ceramic substrate 20 also has an electrode 24. The electrode 24 is disposed inside the ceramic substrate 20. The electrode 24 is formed of a conductive material such as tungsten or molybdenum. The electrode 24 is connected to an external power supply via an electrode terminal (not shown) inserted through the holes 14 and 23. Examples of the electrode 24 include a high-frequency electrode, a chuck electrode, and a heater electrode. The ceramic substrate 20 corresponds to a "plate-like member" in the claims.

[0032] The bonded body 5, which is made up of the base 10 and the ceramic substrate 20, has a hole 5a formed therein, which connects the hole 14 formed in the base 10 with the hole 23 formed in the ceramic substrate 20. The hole 5a is used as a terminal hole through which a power supply terminal (not shown) is inserted to supply power to the electrode 24 of the ceramic substrate 20, a gas hole through which helium gas is supplied to the back surface of the substrate W, a lift pin hole through which a lift pin (not shown) is inserted to lift the substrate W from the ceramic substrate 20, a sensor hole through which a temperature sensor (not shown) is inserted to measure the temperature of the mounting surface 21, etc. Note that the bonded body 5 may have a countersunk hole with a bottom formed therein instead of or in place of the hole 5a.

[0033] Next, the details of the refrigerant flow path 30 will be described. Fig. 3 is a second cross-sectional view of the holding device 1. Fig. 3 shows a cross-section along line AA shown in Fig. 2 (a cross-section cut on the xy plane). The cross-section shown in Fig. 3 is a cross-section of the second base 12 in which the groove 13 is formed. As shown in Fig. 3, the refrigerant flow path 30 is formed in a substantially spiral shape. The refrigerant flow path 30 includes a flow path inlet IN through which the refrigerant flows into the refrigerant flow path 30, and a flow path outlet OUT through which the refrigerant flows out of the refrigerant flow path 30.

[0034] The refrigerant flow path 30 also includes a plurality of branching and merging sections 31. At each of the branching and merging sections 31, one refrigerant flow path 30 branches into two flow paths, and the two flow paths merge into one refrigerant flow path 30. Hereinafter, the two flow paths at the branching and merging section 31 are referred to as a main flow path M and a branch flow path T. That is, the portion of the refrigerant flow path 30 that corresponds to the branching and merging section 31 includes the main flow path M and the branch flow path T. In the retention device 1 of this embodiment, at each of the branching and merging sections 31, an island-shaped section (illustrated as island-shaped section IS in FIG. 5 ) without a hole 14 is formed between the branched main flow path M and the branch flow path T. In this embodiment, no hole 14 is formed in the island-shaped section, but in other embodiments, the island-shaped section may have a hole 14.

[0035] FIG. 4 is an explanatory diagram of the cross section of the main channel M and the cross section of the tributary channel T. The cross sections of the main channel M and the tributary channel T are cross sections perpendicular to the direction in which the main channel M and the tributary channel T extend. FIG. 4 shows a cross section (a cross section cut on the yz plane) taken along line BB in FIG. 3. Note that FIG. 4 also does not show the bonding layer that bonds the first base 11 and the second base 12. The main channel M is a channel with a larger cross-sectional area than the tributary channel T. The tributary channel T is a channel with a smaller cross-sectional area than the main channel M. As shown in FIG. 4, the cross sections of the main channel M and the tributary channel T are each rectangular. Note that in FIG. 4, the outline of the cross section of the main channel M is shown as a sawtooth shape to represent the degree of arithmetic mean roughness, which will be described later, but the cross section of the main channel M as a whole is rectangular.

[0036] The length Dm along the thickness direction of the base 10 (the z-axis direction in this embodiment) in the cross section of the main flow channel M shown in Fig. 4 is approximately the same as the length Dt along the thickness direction of the base 10 (the z-axis direction in this embodiment) in the cross section of the tributary flow channel T. On the other hand, the length Wm along the direction perpendicular to the thickness direction of the base 10 (the y-axis direction in Fig. 4) in the cross section of the main flow channel M shown in Fig. 4 is longer than the length Wt along the direction perpendicular to the thickness direction of the base 10 (the y-axis direction in Fig. 4) in the cross section of the tributary flow channel T.

[0037] Figure 5 is an enlarged view of the branching and merging section 31. More specifically, Figure 5 is an enlarged view of the branching and merging section 31 along the line BB shown in Figure 3. The end of the main channel M is defined by a perpendicular line drawn from the end of the line Lm on the main channel M side that defines the island-shaped section IS. The end of the tributary channel T is defined by a perpendicular line drawn from the end of the line Lt on the tributary channel T side that defines the island-shaped section IS. In Figure 5, the areas considered to be the main channel M and the tributary channel T are hatched.

[0038] FIG. 6 is an explanatory diagram of the planes that define the main channel M and the planes that define the tributary channel T. Of the cross sections shown in FIG. 4, FIG. 6 only shows the cross sections of the main channel M and the tributary channel T. First, the demarcation planes ma to md that define the main channel M will be explained. The demarcation plane ma is the plane that defines the positive side of the main channel M in the z-axis direction. The demarcation plane mb is the plane that defines the negative side of the main channel M in the z-axis direction. The demarcation plane mc is the plane that defines the positive side of the main channel M in the y-axis direction. The demarcation plane md is the plane that defines the negative side of the main channel M in the y-axis direction. The demarcation planes ma to md are collectively referred to as the main channel demarcation planes.

[0039] Next, we will explain the demarcation surfaces ta to td, which are the surfaces that define the tributary channel T. The demarcation surface ta is the surface that defines the positive side of the tributary channel T in the z-axis direction. The demarcation surface tb is the surface that defines the negative side of the tributary channel T in the z-axis direction. The demarcation surface tc is the surface that defines the positive side of the tributary channel T in the y-axis direction. The demarcation surfaces ta to td are collectively referred to as tributary channel demarcation surfaces.

[0040] The value representing the roughness of the tributary channel defining surfaces is smaller than the value representing the roughness of the main channel defining surfaces. Both the value representing the roughness of the tributary channel defining surfaces and the value representing the roughness of the main channel defining surfaces are arithmetic mean roughness values ​​specified in accordance with JIS B 0601:2013. That is, the value representing the roughness of the tributary channel defining surfaces is the arithmetic mean roughness value of the defining surfaces ta to td. The value representing the roughness of the main channel defining surfaces is the arithmetic mean roughness value of the defining surfaces ma to md. Furthermore, the value representing the roughness of the main channel defining surfaces divided by the value representing the roughness of the tributary channel defining surfaces is 1.0 or more and less than 20.0. In other words, the value representing the arithmetic mean roughness of the defining surfaces ma to md divided by the arithmetic mean roughness of the defining surfaces ta to td is 1.0 or more and less than 20.0. The roughness of the tributary channel defining surfaces is preferably 0.5 to 1.5 μm. The roughness of the main flow path defining surface is preferably 1.5 to 10.0 μm.

[0041] Furthermore, when demarcation surfaces ma and mb, which are opposed to each other along the thickness direction of the base 10 (in this embodiment, the z-axis direction) among the flow path demarcation surfaces, are referred to as first opposing surfaces, demarcation surface ma, which is one of the first opposing surfaces, is rougher than demarcation surface mb, which is the other first opposing surface. In other words, the arithmetic mean roughness value of demarcation surface ma is greater than the arithmetic mean roughness value of demarcation surface mb.

[0042] Furthermore, when demarcation surfaces mc and md, which are opposed to each other along a direction perpendicular to the thickness direction of base 10 (the y-axis direction in FIG. 4) among the main flow path demarcation surfaces, are referred to as second opposing surfaces, both of the second opposing surfaces (demarcation surfaces mc and md) are rougher than demarcation surface mb, which is the other first opposing surface. In other words, the arithmetic mean roughness values ​​of demarcation surfaces mc and md are each greater than the arithmetic mean roughness value of demarcation surface mb.

[0043] Furthermore, when demarcation surfaces ta and tb, which are opposed to each other along the thickness direction of the base 10 (in this embodiment, the z-axis direction), are referred to as third opposing surfaces, demarcation surface ta, which is one of the third opposing surfaces, is rougher than demarcation surface tb, which is the other third opposing surface. In other words, the arithmetic mean roughness value of demarcation surface ta is greater than the arithmetic mean roughness value of demarcation surface tb.

[0044] Furthermore, when demarcation surfaces tc and td, which are opposed to each other along a direction perpendicular to the thickness direction of base 10 (the y-axis direction in FIG. 4 ), are referred to as fourth opposing surfaces, the fourth opposing surfaces (demarcation surfaces tc and td) are both rougher than demarcation surface tb, which is the other third opposing surface. In other words, the arithmetic mean roughness values ​​of demarcation surfaces tc and td are each greater than the arithmetic mean roughness value of demarcation surface tb.

[0045] The smaller the cross-sectional area of ​​a flow path in its transverse cross section, the greater the pressure loss of the fluid flowing inside the flow path. In the base 10 provided in the holding device 1 described above, the value representing the roughness of the tributary flow path defining surface is smaller than the value representing the roughness of the main flow path defining surface, and therefore the tributary flow path defining surface is smoother than the main flow path defining surface. This makes it possible to prevent the pressure loss of the refrigerant flowing inside the tributary flow path T, which has a smaller cross-sectional area in its transverse cross section than the main flow path M, from increasing.

[0046] Furthermore, in the base 10 provided in the holding device 1, the surface defining the main flow path is rougher than the surface defining the tributary flow path by a factor of 1.0 or more and less than 20.0. In other words, because the surface defining the tributary flow path is smoother than the surface defining the main flow path, it is possible to prevent an increase in pressure loss of the refrigerant flowing inside the tributary flow path, which has a smaller cross-sectional area in its transverse cross section than the main flow path.

[0047] Furthermore, in the base 10 provided in the holding device 1, the demarcation surface ma is rougher than the demarcation surface mb. Therefore, when the coolant flows inside the main flow path M, turbulence of the coolant is more likely to occur at the demarcation surface ma than at the demarcation surface mb. Such turbulent coolant flow increases the cooling efficiency, and therefore the cooling efficiency on the demarcation surface ma side of the base 10 can be improved. Because the demarcation surface ma is the surface that defines the positive side of the main flow path M in the z-axis direction, improved cooling efficiency on the demarcation surface ma side leads to improved cooling efficiency of the mounting surface 21 on which the substrate W is placed.

[0048] Furthermore, in the base 10 provided in the holding device 1, the demarcation surfaces mc and md are rougher than the demarcation surface mb. Therefore, when the coolant flows inside the main flow path M, turbulence of the coolant is likely to occur not only at the demarcation surface ma but also at the demarcation surfaces mc and md. This makes it possible to further improve the cooling efficiency on the demarcation surface ma side of the base 10. In other words, it is possible to further improve the cooling efficiency of the support surface 21 on which the substrate W is placed.

[0049] Furthermore, in the base 10 provided in the holding device 1, the demarcation surface ta is rougher than the demarcation surface tb. Therefore, when the coolant flows inside the tributary channel T, turbulence of the coolant is more likely to occur at the demarcation surface ta than at the demarcation surface tb, thereby improving the cooling efficiency on the demarcation surface ta side of the base 10. Because the demarcation surface ta is the surface that defines the positive side of the tributary channel T in the z-axis direction, improving the cooling efficiency on the demarcation surface ta side leads to improving the cooling efficiency of the mounting surface 21 on which the substrate W is placed.

[0050] Furthermore, in the base 10 provided in the holding device 1, the demarcation surfaces tc and td are rougher than the demarcation surface tb. Therefore, when the coolant flows through the branch channel T, turbulence of the coolant is likely to occur not only at the demarcation surface ta but also at the demarcation surfaces tc and td. This makes it possible to further improve the cooling efficiency on the demarcation surface ta side of the base 10. In other words, it is possible to further improve the cooling efficiency of the support surface 21 on which the substrate W is placed.

[0051] <Modification of this embodiment> The present disclosure is not limited to the above-described embodiments, and can be implemented in various forms without departing from the spirit thereof. For example, the following modifications are also possible.

[0052] FIG. 7 is an explanatory diagram of another example of the cross section of the main flow path M and the cross section of the tributary flow path T. Regarding the main flow path M and the tributary flow path T included in each of the branching and merging sections 31, the shapes of the cross sections of the main flow path M and the tributary flow path T are not limited to the shapes shown in FIG. 4. For example, as shown in FIG. 7, the length Dt of the tributary flow path T along the thickness direction of the base 10 (the z-axis direction in this embodiment) in the cross section may be longer than the length Dm of the main flow path M along the thickness direction of the base 10 (the z-axis direction in this embodiment) in the cross section. Note that in FIG. 7, the length Wm of the main flow path M along the direction perpendicular to the thickness direction of the base 10 (the y-axis direction in FIG. 7) in the cross section is longer than the length Wt of the tributary flow path T along the direction perpendicular to the thickness direction of the base 10 (the y-axis direction in FIG. 7), as in FIG. 4. Even with such a shape, it is possible to suppress an increase in pressure loss of the refrigerant flowing inside the tributary flow path T, which has a smaller cross-sectional area in the cross section than the main flow path M. Furthermore, the cross-sectional shapes of the main flow path M and the tributary flow path T are not limited to the shapes shown in Figures 4 and 7, and the length Dm may be longer than the length Dt, and the length Wt may be longer than the length Wm.

[0053] In the above embodiment, the cross section of the main flow path M and the cross section of the tributary flow path T are each rectangular as shown in Fig. 4, but are not limited to this. The cross section of the main flow path M and the cross section of the tributary flow path T may each have any shape other than a rectangular shape. Regardless of the shape, it is preferable that the arithmetic mean roughness value of the portion of the cross section of the main flow path M and the cross section of the tributary flow path T on the side of the mounting surface 21 (the side of the ceramic substrate 20) is larger than the arithmetic mean roughness value of the portion on the opposite side to the side of the mounting surface 21 (the side of the first base 11), from the viewpoint of improving the cooling efficiency of the mounting surface 21.

[0054] In the above embodiment, at each of the branching and merging sections 31, one refrigerant flow path 30 branches into two flow paths, and the two flow paths merge into one refrigerant flow path 30. However, this is not limited to this. Some of the branching and merging sections 31 may have one refrigerant flow path 30 branching into three or more flow paths, and the three or more flow paths merge into one refrigerant flow path 30. Even in such a case, by reducing the arithmetic mean roughness of the flow path defining surface that defines a branched flow path with a smaller cross-sectional area, it is possible to prevent an increase in pressure loss of the refrigerant flowing inside the flow path.

[0055] In the above embodiment, the holding device 1 includes the base 10, the ceramic substrate 20, and a bonding layer (not shown), but the configuration of the holding device 1 is not limited to this. The holding device 1 may be a single bonded body 5 in which a portion corresponding to the base 10 and a portion corresponding to the ceramic substrate 20 are integrated. Furthermore, the portion corresponding to the bonding layer may not be present, and the member corresponding to the base 10 and the member corresponding to the ceramic substrate 20 may be bonded by diffusion bonding.

[0056] In the above embodiment, an example is shown in which the groove 13 constituting the refrigerant flow path 30 is formed in the second base 12, but the groove 13 may also be formed in the first base 11, or may be formed in both the first base 11 and the second base 12.

[0057] In the above embodiment, the high-frequency electrode, the chuck electrode, and the heater electrode are arranged on the ceramic substrate. However, these electrodes may be arranged on the base.

[0058] This aspect has been described above based on embodiments and modifications. However, the above-described embodiments are intended to facilitate understanding of this aspect and are not intended to limit this aspect. This aspect may be modified or improved without departing from the spirit and scope of the claims, and equivalents thereof are included in this aspect. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

[0059] [Application example 1] A base having a refrigerant flow path formed therein through which a refrigerant flows, the refrigerant flow path includes a branched portion into a main flow path and a branch flow path having a smaller cross-sectional area in a transverse cross section than the main flow path, A base characterized in that a value representing the roughness of a tributary flow path defining surface, which is a surface defining the tributary flow path, is smaller than a value representing the roughness of a main flow path defining surface, which is a surface defining the main flow path. [Application example 2] The base according to Application Example 1, A base characterized in that a value representing the roughness of the main flow path defining surface divided by a value representing the roughness of the tributary flow path defining surface is 1.0 or more and less than 20.0. [Application example 3] The base according to Application Example 1 or Application Example 2, The cross section of the main flow path is rectangular, A base characterized in that, among the main flow path defining surfaces, first opposing surfaces that face each other along the thickness direction of the base, one of the first opposing surfaces is rougher than the other of the first opposing surfaces. [Application example 4] The base according to any one of Application Examples 1 to 3, A base characterized in that the second opposing surfaces of the main flow path defining surfaces that face each other along a direction perpendicular to the thickness direction of the base are both rougher than the other first opposing surfaces. [Application example 5] The base according to any one of Application Examples 1 to 4, The cross section of the branch channel is rectangular, A base characterized in that, among the tributary flow path defining surfaces, third opposing surfaces that face each other along the thickness direction of the base, one of the third opposing surfaces is rougher than the other of the third opposing surfaces. [Application Example 6] The base according to any one of Application Examples 1 to 5, A base characterized in that the fourth opposing surfaces of the tributary flow path defining surfaces that face each other along a direction perpendicular to the thickness direction of the base are both rougher than the other third opposing surfaces. [Application Example 7] The base according to any one of Application Examples 1 to 6, Each of the cross sections of the main channel and the branch channel is rectangular, a length of the tributary channel in a cross section along a thickness direction of the base is longer than a length of the main channel in a cross section along the thickness direction; A base characterized in that the length of the cross section of the main flow path along a direction perpendicular to the thickness direction of the base is longer than the length of the cross section of the branch flow path along a direction perpendicular to the thickness direction. [Application Example 8] A holding device, A base according to any one of Application Examples 1 to 7; A holding device comprising: a plate-shaped member having a placement surface on which an object is placed, the plate-shaped member being supported by the base. [Explanation of symbols]

[0060] 1...Holding device 5…Zygote 5a…hole 10...Foundation 11...First Foundation 11a, 11b...main surface 12...Second Foundation 12a, 12b…main surface 13...Groove 14...hole 20...Ceramic substrate 20a, 20b…main surface 21...Placement surface 22...Focus ring mounting surface 23…hole 24...Electrode 30... Refrigerant flow path 31... Junction FR...Focus ring IS…island IN: Flow path inlet M: Main channel OUT…Flow path outlet T…tributary channel ma~md...Definition plane ta~td...Definition plane

Claims

1. A base having a refrigerant flow path formed therein through which a refrigerant flows, the refrigerant flow path includes a branched portion into a main flow path and a branch flow path having a smaller cross-sectional area in a transverse cross section than the main flow path, A base characterized in that a value representing the roughness of a tributary flow path defining surface, which is a surface defining the tributary flow path, is smaller than a value representing the roughness of a main flow path defining surface, which is a surface defining the main flow path.

2. 2. The base according to claim 1, A base characterized in that a value representing the roughness of the main flow path defining surface divided by a value representing the roughness of the tributary flow path defining surface is equal to or greater than 1.0 and less than 20.

0.

3. 2. The base according to claim 1, The cross section of the main flow path is rectangular, A base characterized in that, among the main flow path defining surfaces, first opposing surfaces that face each other along the thickness direction of the base, one of the first opposing surfaces is rougher than the other first opposing surface.

4. 4. The base according to claim 3, A base characterized in that the second opposing surfaces of the main flow path defining surfaces that face each other along a direction perpendicular to the thickness direction of the base are both rougher than the other first opposing surfaces.

5. 2. The base according to claim 1, The cross section of the branch channel is rectangular, A base characterized in that, among the tributary flow path defining surfaces, third opposing surfaces that face each other along the thickness direction of the base, one of the third opposing surfaces is rougher than the other of the third opposing surfaces.

6. 6. The base according to claim 5, A base characterized in that the fourth opposing surfaces of the tributary flow path defining surfaces that face each other along a direction perpendicular to the thickness direction of the base are both rougher than the other third opposing surfaces.

7. 2. The base according to claim 1, Each of the cross sections of the main channel and the branch channel is rectangular, a length of the tributary channel in a cross section along a thickness direction of the base is longer than a length of the main channel in a cross section along the thickness direction; A base characterized in that the length of the cross section of the main flow path along a direction perpendicular to the thickness direction of the base is longer than the length of the cross section of the branch flow path along a direction perpendicular to the thickness direction.

8. A holding device, A base according to any one of claims 1 to 7; A holding device comprising: a plate-shaped member having a placement surface on which an object is placed, the plate-shaped member being supported by the base.

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