Base and holding device

Abstract

Another technique for adjusting the in-plane temperature of the mounting surface of a plate-like member in a holding device is provided. [Solution] A plate-shaped base having a pair of main surfaces and an internal flow path through which a refrigerant flows, the flow path has at least one branching and merging section including a branching section that branches the flow path into a first branching flow path and a second branching flow path, and a merging section that merges the first branching flow path and the second branching flow path into one, and the cross-sectional area of ​​the second branching flow path is smaller than the cross-sectional area of ​​the first branching 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 plate-shaped member having a support surface on which an object is placed and a 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 locally changing the flow rate of the coolant by providing a protruding member on a base on which a flow path is formed. [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] Recently, semiconductor manufacturing processes have become increasingly heat-intensive, and maintaining a substrate placed on the support surface of a holding device at a predetermined process temperature requires transferring and dissipating a large amount of heat. Such holding devices may be provided with terminal holes for inserting power supply terminals to supply power to electrodes, gas holes for supplying He gas to the backside of the wafer, and lift pin holes for inserting lift pins to lift the wafer from the support surface. Due to constraints such as these various holes, uneven placement of the coolant flow paths can result in significant localized temperature distribution on the support surface. However, the technology disclosed in Patent Document 1 may not achieve the desired effect due to the constraints of the various holes and other factors.

[0005] An object of the present disclosure is to provide another technique for adjusting the in-plane temperature of the mounting surface of a plate-like member in a holding device. [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 aspects.

[0007] (1) According to one aspect of the present disclosure, there is provided a plate-shaped base having a pair of main surfaces and including a flow path therein through which a refrigerant flows, wherein the flow path has at least one branching and merging section including a branching section that branches the flow path into a first branching flow path and a second branching flow path, and a merging section that merges the first branching flow path and the second branching flow path, and a cross-sectional area of ​​the second branching flow path is smaller than a cross-sectional area of ​​the first branching flow path.

[0008] According to this configuration, the refrigerant flowing through one flow path branches into a first branch flow path and a second branch flow path, and then merges and flows through one flow path again. Therefore, the area that is cooled can be made larger than when the refrigerant flows through only one flow path, for example.

[0009] The cross-sectional area of ​​the second branch flow path is smaller than that of the first branch flow path. Here, the cross-sectional area refers to the area of ​​a transverse section, which is a section perpendicular to the center line of the flow direction of each flow path. By appropriately adjusting the cross-sectional area, the flow rate and flow velocity of the refrigerant can be changed. Therefore, by providing the second branch flow path at a location where fine temperature adjustment is desired, it is possible to finely adjust the temperature of the main surface of the base. As a result, it is possible to improve the in-plane temperature uniformity on the main surface of the base and to achieve a desired temperature difference within the surface.

[0010] (2) In the base of the above embodiment, the flow path may have a spiral or bent portion, the first branch flow path may be formed along the flow path, and the second branch flow path may be formed to connect adjacent first branch flow paths. When adjacent first branch flow paths are formed along the flow path and connected by a second flow path, the amount of refrigerant flowing through the first flow path is reduced compared to the amount of refrigerant flowing through the flow path before branching, allowing the temperature of that portion to be slightly increased. This configuration can also improve the in-plane temperature uniformity on the main surface of the base, or provide a desired temperature difference within the surface.

[0011] (3) In the base of the above embodiment, the first branch flow path and the second branch flow path may face each other. Even in this case, the cross-sectional area of ​​the second branch flow path is smaller than the cross-sectional area of ​​the first branch flow path, so that by adjusting the difference in cross-sectional areas, it is possible to adjust the temperature at a desired location, improve the in-plane temperature uniformity on the main surface of the base, or provide a desired temperature difference within the surface.

[0012] (4) In the base of the above embodiment, the flow path may have a plurality of the branching and merging sections. By providing the plurality of branching and merging sections at locations where temperature adjustment is desired, it is possible to further improve the uniformity of the temperature within the main surface of the base, or to provide a desired temperature difference at desired locations within the surface.

[0013] (5) In the base of the above aspect, the second branch flow path may have a first portion having a predetermined depth within the second branch flow path and a second portion having a depth different from the depth of the first portion. In this way, the cooling of the base by the refrigerant flowing through the second branch flow path can be more precisely adjusted.

[0014] (6) According to another aspect of the present disclosure, there is provided a holding device. The holding device includes a plate-shaped portion having a mounting surface on which an object is placed, and a base supporting the plate-shaped portion, the base being the base of the above-described aspect. The holding device of this aspect has the base of the above-described aspect, which makes it possible to improve the uniformity of the temperature within the mounting surface of the holding device and to provide a desired temperature difference within the surface.

[0015] The present disclosure can be realized in various forms, for example, in the form of a semiconductor manufacturing apparatus including a holding device, a manufacturing method for a holding device, a manufacturing method for a semiconductor, etc. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 2 is a perspective view of the holding device of the first embodiment. [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 branching and merging portion of the first embodiment. [Figure 5] FIG. 4 is an explanatory diagram showing the depths of a first branch channel and a second branch channel. [Figure 6] FIG. 3 is an explanatory diagram showing a first branch channel and a second branch channel. [Figure 7] FIG. 10 is an explanatory diagram showing a flow path of a holding device according to a second embodiment. [Figure 8] FIG. [Figure 9] FIG. 2 is an explanatory diagram showing an enlarged view of the vicinity of the branching portion and the merging portion of the branching and merging portion. [Figure 10] FIG. 4 is an explanatory diagram showing the depths of a first branch channel and a second branch channel. [Figure 11] FIG. 10 is a diagram showing the temperature adjustment effect of a branching and merging portion. [Figure 12] FIG. 10 is an explanatory diagram showing the depth of branch flow paths in a holding device according to a third embodiment. [Figure 13] FIG. 10 is an explanatory view showing a flow path of a holding device according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] First Embodiment FIG. 1 is a perspective view of a holding device 1 according to a first embodiment of the present disclosure. FIG. 2 is a first cross-sectional view of the holding device 1 according to the present embodiment. The holding device 1 is an electrostatic chuck that attracts and holds a substrate W by electrostatic attraction. 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 joint (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 FS installed on the outer periphery of the ceramic substrate 20. For convenience, in FIGS. 1 and 2, the stacking direction of the base 10 and the ceramic substrate 20 is defined as the z-axis direction, and an x-axis that intersects perpendicularly with the z-axis and a y-axis that intersects perpendicularly with the z-axis and the x-axis are shown. 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.

[0018] The base 10 is a sintered body primarily composed of silicon carbide (SiC) and is a generally cylindrical member that serves as the base of the holding device 1. Here, "primary component" refers to the component with the highest content. By using silicon carbide, which has high corrosion resistance, as the primary component of the base 10, it is possible to use an aqueous refrigerant. Silicon carbide also has high thermal conductivity and is therefore suitable for use as a ceramic substrate for cooling. While the thermal conductivity of the base 10 is not particularly limited, it is preferable that the base 10 be made of ceramics with a thermal conductivity of 70 W / mK or higher. Furthermore, silicon carbide is electrically conductive, so it can also serve as an electrode for high-frequency current.

[0019] The material forming the base 10 is not limited to a material primarily composed of silicon carbide. The base 10 may also be formed from aluminum (Al), titanium (Ti), molybdenum (Mo), tungsten (W), alloys thereof, SUS, a metal-ceramic composite (MMC) such as Al-SiC, or a material primarily composed of ceramics such as aluminum nitride (AlN) or alumina (Al2O3). By forming the base 10 from a ceramic-metal composite, it becomes easier to adjust the coefficient of thermal expansion (CTE) and improve toughness, making it easier to use as a base.

[0020] The thickness of the base 10 is not particularly limited, but is preferably 10 mm to 50 mm, and 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".

[0021] 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.

[0022] 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 an adhesive 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. 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 or more layer structure.

[0023] 2, the first base 11 is located on the most negative side in the z-axis direction in the holding device 1. The first base 11 is a plate-like member having a substantially circular planar shape and has a pair of main surfaces 11a, 11b. The first base 11 has an inlet (not shown) formed on one of the pair of main surfaces 11a, 11b, through which a refrigerant flowing through a flow path 30 (described later) flows into the flow path 30, and an outlet (not shown) formed through which the refrigerant flows out of the flow path 30.

[0024] The second base 12 is stacked on the first base 11 on the positive side of the first base 11 in the z-axis direction. The second base 12 is a substantially circular, planar, plate-like member having approximately the same size as the first base 11, and has a pair of main surfaces 12a and 12b. Of the pair of main surfaces 12a and 12b of the second base 12, the main surface 12b on the negative side in the z-axis direction has a groove 13 formed therein that serves as a flow path 30 through which the refrigerant flows. When the first base 11 and the second base 12 are joined together, the first base 11 serves as a cover for the groove 13, thereby forming the flow path 30. The base 10 has a plurality of holes 14 formed along the z-axis direction of the holding device 1. The detailed shape of the flow path 30 will be described later.

[0025] The base 10 can be manufactured by various known manufacturing methods. For example, raw material powder is subjected to CIP (cold isostatic pressing) molding, the molded body is processed, the molded body is degreased and fired, and the fired body is processed again to complete the base 10.

[0026] The grooves 13 of the second base 12 may be formed by machining the molded body before firing, or may be formed by machining after firing. Furthermore, when the second base 12 is formed from a conductive material such as silicon carbide, the grooves 13 may be formed by electric discharge machining.

[0027] 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.

[0028] The ceramic substrate 20 is a plate-shaped member disposed on the positive side of the base 10 in the z-axis direction. The ceramic substrate 20 is mainly composed of ceramic. The ceramic substrate 20 of this embodiment is formed from a material mainly composed of aluminum oxide. Note that the ceramic substrate 20 may also be formed from other ceramics such as aluminum nitride, silicon carbide, or yttria (YO). The ceramic substrate 20 has a pair of main surfaces 20a and 20b.

[0029] The ceramic base 20 has a pair of main surfaces 20a, 20b, and a mounting surface 21 on which a substrate W is mounted is formed on one of the main surfaces 20a opposite the base 10. A focus ring mounting surface 22 on which a focus ring FS is mounted is formed on the outer periphery of the one main surface 20a of the ceramic base 20. The other main surface 20b of the pair of main surfaces 20a, 20b of the ceramic base 20 is bonded to the second base 12 by an adhesive layer (not shown). The ceramic base 20 has holes 23 formed therein that communicate with the multiple holes 14 formed in the base 10. Note that methods for bonding the base 10 and the ceramic base 20 include, but are not limited to, metal bonding, resin bonding, and bonding using an inorganic material. Furthermore, the base 10 and the ceramic base 20 may be integrally formed of a single material without a bonding layer.

[0030] The ceramic substrate 20 of this embodiment 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 into 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 of this embodiment is also referred to as a "plate-shaped portion."

[0031] The holding device 1 of this embodiment has a hole 5a penetrating the bonded body 5 made of the base 10 and the ceramic substrate 20 in the z-axis direction by the hole 14 formed in the base 10 and the hole 23 formed in the ceramic substrate 20. The hole 5a in the bonded body 5 is used as a terminal hole for inserting a power supply terminal (not shown) for supplying power to the electrode 24 of the ceramic substrate 20, a gas hole for supplying helium gas to the backside of the substrate W, a lift pin hole for inserting a lift pin (not shown) for lifting the substrate W from the ceramic substrate 20, a sensor hole for inserting a temperature sensor (not shown) for measuring the temperature of the mounting surface 21, and the like. Note that although the hole 5a in the bonded body 5 of this embodiment is described as penetrating the bonded body 5 in the z-axis direction, it does not have to penetrate the bonded body 5. Specifically, for example, the hole 14 penetrating the base 10 may have a bottom. When the hole 14 has a bottom, the other main surface 20b of the ceramic base 20 or a countersunk hole formed in the other main surface 20b becomes the bottom of the hole 5a.

[0032] Next, the detailed shape of the flow path 30 of the holding device 1 will be described. Fig. 3 is a second cross-sectional view of the holding device 1. Fig. 3 is a cross-sectional view taken along line AA in Fig. 2, specifically, a cross-section perpendicular to the central axis C5 of the bonded body 5 including the flow channel 30, and is a cross-section of the second base 12 in which the groove 13 is formed. Hereinafter, the cross-section shown in Fig. 3 will also be referred to as a "transverse cross-section including the flow channel 30."

[0033] The flow path 30 of this embodiment is formed in a substantially spiral shape, as shown in Fig. 3. The flow path 30 has a flow path inlet 30a through which the refrigerant from the outside flows into the flow path 30, and a flow path outlet 30b through which the refrigerant that has flowed through the flow path 30 flows out of the flow path 30. That is, in the holding device 1 of this embodiment, the refrigerant flows into the flow path 30 near the central axis C5 of the bonded body 5, flows counterclockwise toward the outer periphery of the base 10, and is discharged to the outside of the base 10 from the flow path outlet 30b. In Fig. 3, the flow of the refrigerant near the flow path inlet 30a and the flow path outlet 30b is indicated by arrows.

[0034] The flow path 30 of the holding device 1 has a plurality of branching and merging sections 31. Each of the plurality of branching and merging sections 31 has a branching section that branches the flow path 30 into two branching flow paths, and a merging section that merges the two branching flow paths branched by the branching section into one. In the holding device 1 of this embodiment, for each of the plurality of branching and merging sections 31, an island-shaped section without a hole 14 is formed between the two branching flow paths. 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] As shown in the figure, in a cross section including the flow path 30, the branching and merging portion 31 is formed so that the two branching flow paths are curved in directions away from each other and face each other.

[0036] Fig. 4 is an explanatory diagram of the branching and merging section 31 of the first embodiment. Fig. 4 is an enlarged view of part B in Fig. 3, and is an enlarged cross-sectional view including one of the plurality of branching and merging sections 31. The branching and merging section 31 shown in Fig. 4 has a branching section 313 that branches the flow path 30 into a first branching flow path 311 and a second branching flow path 312, and a merging section 314 that merges the first branching flow path 311 and the second branching flow path 312 branched by the branching section 313 into one.

[0037] In the holding device 1, the branching and merging section 31 is formed such that the first branch channel 311 and the second branch channel 312 are curved away from each other and face each other in a cross section including the channel 30 as shown in FIG. 4. Specifically, using the center line C30 of the channel 30 shown in FIG. 4, the first branch channel 311 and the second branch channel 312 are formed so as not to include the center line C30 of the channel 30. The first branch channel 311 is formed so as to bulge inward of the joined body 5 toward the central axis C5 of the joined body 5, as viewed from the center line C30 of the channel 30. The second branch channel 312 is formed so as to bulge outward of the joined body 5 in a direction away from the central axis C5 of the joined body 5, as viewed from the center line C30 of the channel 30. As a result, the island-shaped portion 315 sandwiched between the first branch flow path 311 and the second branch flow path 312 becomes a portion that is cooled to a relatively large extent by the refrigerant flowing through each of the first branch flow path 311 and the second branch flow path 312, and therefore the range that is cooled to a relatively large extent by the refrigerant can be increased.

[0038] 5 is an explanatory diagram showing the depths of the first branch channel 311 and the second branch channel 312. FIG. 5(A) shows a cross section taken along line CC in FIG. 4, illustrating a transverse cross section of the channel 30. FIG. 5(B) shows a cross section taken along line DD in FIG. 4, illustrating a transverse cross section of the first branch channel 311 and the second branch channel 312. Here, the transverse cross section is a cross section perpendicular to the center line of the channel in the flow direction, and in this example, is a cross section parallel to the central axis C5 of the bonded body 5.

[0039] As shown in FIG. 5B, the depth D2 of the second branch channel 312 is smaller than the depth D1 of the first branch channel 311, and the width W2 of the second branch channel 312 is the same as the width W1 of the first branch channel 311. Therefore, the cross-sectional area of ​​the second branch channel 312 is smaller than the cross-sectional area of ​​the first branch channel 311. In this embodiment, the depth D1 of the first branch channel 311 is the same as the depth D0 of the channel 30, but the depth D1 of the first branch channel 311 may be different from the depth D0 of the channel 30. As shown in the figure, the depth of each channel is the distance from the ceiling to the bottom of the channel. The cross-sectional area of ​​each branch channel is measured at multiple locations (e.g., five evenly spaced locations) and the average value is used.

[0040] FIG. 6 is an explanatory diagram showing the first branch channel 311 and the second branch channel 312. In FIG. 6, the second branch channel 312 is indicated by diagonal hatching. In this embodiment, the first branch channel 311 has a constant depth (depth D1), and the second branch channel 312 has a constant depth (depth D2) throughout (the hatched portion in the figure). Note that in FIG. 6, the ends of the first branch channel 311 and the second branch channel 312 are defined by lines perpendicular to the inner lines L1 and L2 of the branch channels, respectively, as an example. The method for determining the ends of the first branch channel 311 and the second branch channel 312 is not limited to the example shown in FIG. 6 and can be determined by various methods. For example, the ends of the first branch channel 311 and the second branch channel 312 may be defined by lines perpendicular to the center line C30 of the channel 30.

[0041] In the holding device 1 of this embodiment, the flow path 30 of the base 10 has a branching and merging section 31, and the refrigerant flowing through one flow path 30 branches into a first branching flow path 311 and a second branching flow path 312, and then merges and flows again through one flow path 30.Therefore, the area that is cooled can be made larger than when the refrigerant flows through only one flow path, for example.

[0042] Furthermore, the cross-sectional area of ​​the second branch flow path 312 is smaller than the cross-sectional area of ​​the first branch flow path 311. Because the amount of refrigerant flowing through the second branch flow path 312 is smaller than the amount of refrigerant flowing through the first branch flow path 311, the degree of cooling can be finely adjusted. As a result, it is possible to improve the in-plane temperature uniformity of the main surface 12a of the base 10 and to provide a desired temperature difference within the surface. As a result, it is possible to improve the in-plane temperature uniformity of the mounting surface 21 of the holding device 1 and to provide a desired temperature difference within the surface.

[0043] Second Embodiment FIG. 7 is an explanatory diagram showing a flow path 30A of a holding device 1A of a second embodiment. FIG. 7 is a cross-sectional view corresponding to FIG. 3 of the first embodiment. In the holding device 1A of the second embodiment, the shape of the flow path 30A is different from that of the flow path 30 of the first embodiment. In the holding device 1A, the flow path 30A is formed in a substantially spiral shape as in the first embodiment, but the arrangement of the flow path inlet 30a through which the refrigerant from the outside flows into the flow path 30 and the flow path outlet 30b through which the refrigerant flows through the flow path 30 and exits the flow path 30 is different from that of the flow path 30 of the first embodiment. That is, in the holding device 1A of this embodiment, the refrigerant flows into the flow path 30A from the flow path inlet 30a located on the outer periphery of the base 10A, flows counterclockwise toward the central axis C5 of the base 10, and is discharged to the outside of the base 10 from the flow path outlet 30b located near the central axis C5 of the bonded body 5. In FIG. 7, the flow of the refrigerant near the flow path inlet 30a and the flow path outlet 30b is indicated by arrows. In addition, the shape of the branching and merging section 31A of the flow path 30A is different from that of the branching and merging section 31 of the first embodiment. In the embodiments described below, the same components as those of the holding device 1 of the first embodiment are denoted by the same reference numerals, and reference is made to the preceding description.

[0044] FIG. 8 is an explanatory diagram of the flow path 30A. FIG. 8 shows a cross-sectional view corresponding to FIG. 7. In FIG. 8, the first branch flow path 311A ​​is shown hatched. The end of the first branch flow path 311A ​​is defined in the same manner as in the first embodiment. As shown in the figure, in a cross section including the flow path 30A, the first branch flow path is formed so as to follow the flow path 30A, and the second branch flow path is formed so as to connect adjacent first branch flow paths. In the example shown in FIG. 8, the branching and merging portion 31A has the first branch flow path 311A ​​shown hatched and the second branch flow path 312A.

[0045] In FIG. 8, the flow of refrigerant near branching portion 313A and junction 314A is also indicated by arrows. As shown in the figure, the refrigerant that flows into flow path 30A from flow path inlet 30a branches into first branching flow path 311A ​​and second branching flow path 312A at branching portion 313A and then merges at junction 314A and flows through flow path 30A. That is, the amount of refrigerant flowing through first branching flow path 311A ​​is less than the amount of refrigerant flowing through flow path 30A upstream of branching portion 313A. The amount of refrigerant flowing through flow path 30A downstream of junction 314A is the same as the amount of refrigerant flowing through flow path 30A upstream of branching portion 313A. Therefore, the degree of cooling of the main surface of base 10 near the portion where first branching flow path 311A ​​is located is reduced. In other words, the temperature of the main surface can be higher than when the flow paths are not branched.

[0046] FIG. 9 is an explanatory diagram showing an enlarged view of the vicinity of branch portion 313A and junction portion 314A of branch-junction portion 31A. The widths of first branch channel 311A ​​and second branch channel 312A are shown in the figure. As shown in the figure, widths W3 and W4 of first branch channel 311A ​​and width W5 of second branch channel 312A are approximately equal. As shown in FIG. 8, the width of first branch channel 311A ​​is approximately constant throughout (the hatched portion in the figure), and the width of second branch channel 312A is also approximately constant throughout. In this example, the average width of first branch channel 311A ​​is approximately equal to the average width of second branch channel 312A.

[0047] FIG. 10 is an explanatory diagram showing the depths of the first branch flow path 311A ​​and the second branch flow path 312A. FIG. 10 is a cross-sectional view taken along the line FF in FIG. 9. As shown in the figure, the depth D2 of the second branch flow path 312A is smaller than the depth D1 of the first branch flow path 311A. The depth of the first branch flow path 311A ​​is substantially constant (depth D1) throughout (the hatched portion in the figure), and the depth of the second branch flow path 312A is also substantially constant (depth D2) throughout. Therefore, the cross-sectional area of ​​the second branch flow path 312 is smaller than the cross-sectional area of ​​the first branch flow path 311. In this manner, the amount of refrigerant flowing through the second branch flow path 312A is smaller than the amount of refrigerant flowing through the first branch flow path 311A. Note that, in this embodiment, the depth D1 of the first branch flow path 311A ​​is the same as the depth of the flow path 30A, but the depth D1 of the first branch flow path 311A ​​may be different from the depth of the flow path 30A.

[0048] 11 is a diagram showing the temperature adjustment effect of the branching and merging section 31B of the embodiment, which illustrates the results of simulating the temperature distribution on the setting surface 21 under the simulation conditions shown below. The components of the holding device 1A are as follows: Base 10A: ceramics mainly composed of silicon carbide (SiC) Ceramic substrate 20: ceramics mainly composed of aluminum oxide Focus ring FR: ceramics mainly composed of silicon carbide (SiC) Bonding of each component: Aluminum (Al) bond (metal bonding) The refrigerant was a fluorine-based inert liquid, and the substrate W was a Si wafer. <Heat input conditions> A total of 4 kW of heat is input to the surfaces of the substrate W and focus ring FR. <Refrigerant conditions> Refrigerant at -20°C is circulated at 10L / min.

[0049] 11(A), (C), and (E) show cross sections corresponding to FIG. 7. FIG. 11(A) shows the flow path 30P1 of the holding device 1P1 of the first comparative example, and FIG. 11(B) shows the temperature distribution on the support surface of the holding device 1P1. FIG. 11(C) shows the flow path 30P2 of the holding device 1P2 of the second comparative example, and FIG. 11(D) shows the temperature distribution on the support surface of the holding device 1P2. FIG. 11(E) shows the flow path 30B of the holding device 1B of the embodiment of the present disclosure, and FIG. 11(F) shows the temperature distribution on the support surface of the holding device 1B. FIGS. 11(B), (D), and (F) show the locations corresponding to portions E in FIGS. 11(A), (C), and (D), respectively. As indicated by the color bars in FIG. 11, the darker the area, the lower the temperature, and the whiter the area, the higher the temperature.

[0050] The first comparative example 30P1 does not have a branch flow path (FIG. 11(A)). The second comparative example 30P2 has a branched flow path 30P2 and a branch-junction portion 31P2 having a second branch flow path 312P2 connecting adjacent first branch flow paths 311P2. In this example, the first branch flow path 311P2 and the second branch flow path 312P2 have the same width, depth, and cross-sectional area. In the holding device 1B shown in FIG. 11(E), the flow path 30B has a shape similar to the flow path 30P2 of the second comparative example, but the width of the second branch flow path 312B is narrower than the second branch flow path 312P2 of the second comparative example. The flow paths 30P1, 30P2, and 30B have the same depth. That is, the first branch flow path 311P2, the second branch flow path 312P2, the branch flow path 311B, and the second branch flow path 312B have the same depth.

[0051] The temperature of portion E of the mounting surface of the holding device 1P2 of the second comparative example is lower than that of the holding device 1P1 of the first comparative example. In particular, the temperature at the location where the second branch flow path 312P2 is formed is lower than that of the holding device 1P1 of the first comparative example, and the temperature of portion E as a whole is lower. In the holding device 1P2 of the second comparative example, the flow path 30P2 branches, and by having a branching and merging portion 31P2 having a second branch flow path 312P2 that connects adjacent first branch flow paths 311P2, it can be said that the temperature of portion E of the mounting surface can be lower than that of the holding device 1P1 of the first comparative example.

[0052] The temperature of the E portion of the support surface of the holding device 1B of the embodiment is lower than that of the holding device 1P2 of the second comparative example. In particular, the temperature of the area where the second branch channel 312B is formed is lower than that of the holding device 1P2 of the second comparative example, resulting in a lower temperature throughout the E portion. In the holding device 1B of the embodiment, the width of the second branch channel 312B is different from that of the second branch channel 312P2 of the second comparative example, but the other configurations are the same. Therefore, narrowing the width of the second branch channel 312B can improve the cooling performance of the area. In other words, by making the cross-sectional area of ​​the second branch channel 312B smaller than that of the first branch channel 311B, the cooling performance of the second channel 30P2 can be improved compared to when the cross-sectional areas of the second branch channel and the first branch channel are equal. The cross-sectional area of ​​the second branch channel only needs to be smaller than that of the first branch channel, and either the width or the depth, or both, can be different from that of the first branch channel.

[0053] As described above, the holding devices 1A and 1B of this embodiment can also provide desired cooling performance by arranging the second branch flow passages at desired locations.

[0054] <Third embodiment> 12 is an explanatory diagram showing the depths of the first branch channel 311C and the second branch channel 312C in the holding device 1C of the third embodiment. In the holding device 1C of the third embodiment, the depth of the second branch channel 312C of the channel 30C differs from that of the second embodiment. FIG. 12 illustrates a portion corresponding to FIG. 10.

[0055] As shown in the figure, the second branch flow path 312C of this embodiment has a first portion 318 having a depth D2 and a second portion 319 having a depth D3 that is different from the depth of the first portion 318. This allows for more precise adjustment of the cooling by the refrigerant flowing through the second branch flow path 312C. Note that, although the example shown in FIG. 12 shows an example in which the depth of the second portion 319 is shallower than the first portion 318, the depth of the second portion 319 may also be deeper than the first portion 318. Note that both the depth D2 and the depth D3 are smaller than the depth D1.

[0056] <Fourth embodiment> Fig. 13 is an explanatory diagram showing a flow path 30D of a holding device 1D of a fourth embodiment. Fig. 13 is a diagram showing a cross section corresponding to Fig. 3 of the first embodiment. The flow path 30D of this embodiment includes a portion formed in a bent shape. The portion formed in a bent shape is generally called a "serpentine shape."

[0057] In the holding device 1D of this embodiment, the flow path 30D has two branching and merging sections 31D. In each branching and merging section 31D, a first branching flow path 311D is formed so as to extend along the flow path 30D, and a second branching flow path 312D is formed so as to connect adjacent first branching flow paths 311D. This configuration also makes it possible to improve the uniformity of the in-plane temperature on the main surface of the base 10 and to provide a desired temperature difference within the surface, as in the above embodiment.

[0058] <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.

[0059] In the first embodiment, the flow path 30 has a plurality of branching and merging sections 31, but the number of branching and merging sections that the flow path of the holding device has is not limited to this. It may be one.

[0060] In the first embodiment, the first branch flow path and the second branch flow path face each other, and in the second to fourth embodiments, the first branch flow path is formed along the flow path, and the second branch flow path connects adjacent first branch flow paths. However, the flow path 30 may have one or more types of branch and junctions selected from the branch and junctions of the first embodiment and the branch and junctions of the second to fourth embodiments. In addition, in the branch and junction 31 of the first embodiment, the depth of the second branch flow path may be formed to vary in part.

[0061] In the first embodiment, an example was shown in which the first branch flow path 311 and the second branch flow path 312 are formed to be curved, but the branch flow paths may be formed to be bent (folded).

[0062] In the above embodiment, the holes 14, 23 formed in the holding device penetrate the holding device as shown in Fig. 2. However, the holes 14, 23 do not have to penetrate the base 10.

[0063] In the above embodiment, the holding device includes a base, a ceramic substrate, and a joint, but the configuration of the holding device is not limited to this. The holding device may be a single plate-like member in which a portion corresponding to the base and a portion corresponding to the ceramic substrate are integrated. Furthermore, the portion corresponding to the joint may not be present, and the member corresponding to the base and the member corresponding to the ceramic substrate may be joined by diffusion bonding.

[0064] In the above embodiment, an example was shown in which the groove 13 constituting the flow path 30 was 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.

[0065] In the above embodiment, the high-frequency electrode, chuck electrode, and heater electrode are arranged on the ceramic substrate. However, these electrodes may be arranged on the base.

[0066] 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.

[0067] <Application example 1> A plate-shaped base having a pair of main surfaces and a flow path through which a refrigerant flows, the flow path has at least one branching and merging section including a branching section that branches the flow path into a first branching flow path and a second branching flow path, and a merging section that merges the first branching flow path and the second branching flow path into one, The cross-sectional area of ​​the second branch flow path is smaller than the cross-sectional area of ​​the first branch flow path. Base. <Application example 2> The base according to Application Example 1, the flow path has a spiral or bent portion, the first branch flow path is formed along the flow path, The second branch flow path is formed so as to connect the adjacent first branch flow paths. Base. <Application example 3> The base according to Application Example 1 or Application Example 2, The first branch flow path and the second branch flow path are opposed to each other. Base. <Application Example 4> The base according to any one of Application Examples 1 to 3, The flow path has a plurality of the branching and merging portions. Base. <Application example 5> The base according to any one of Application Examples 1 to 4, The second branch flow path has a first portion having a predetermined depth within the second branch flow path and a second portion having a depth different from the depth of the first portion. Base. <Application Example 6> A holding device, a plate-like portion having a placement surface on which an object is placed; a base supporting the plate-shaped portion; and The base is the base described in any one of Application Examples 1 to 5. holding device. [Explanation of symbols]

[0068] 1,1A,1B,1C,1D…Holding device 5…Zygote 10...Foundation 11a, 11b, 12a, 12b,...base 14,23…holes 20...Ceramic substrate 21...Placement surface 30, 30A, 30B, 30C, 30D...flow path 31, 31A, 31B, 31C, 31D2...Branch and junction 311, 311A, 311B, 311C, 311D...First branch flow path 312, 312A, 312B, 312C, 312D...Second branch flow path 313, 313A...Branch 314,314B…Confluence part 315...Island C30…center line C5…Central axis

Claims

1. A plate-shaped base having a pair of main surfaces and a flow path through which a refrigerant flows, the flow path has at least one branching and merging section including a branching section that branches the flow path into a first branching flow path and a second branching flow path, and a merging section that merges the first branching flow path and the second branching flow path into one, a cross-sectional area of ​​the second branch flow path is smaller than a cross-sectional area of ​​the first branch flow path; the flow path has a spiral or bent portion, the first branch flow path is formed along the flow path, The second branch flow path is formed so as to connect adjacent first branch flow paths. Base.

2. A plate-shaped base having a pair of main surfaces and a flow path through which a refrigerant flows, the flow path has at least one branching and merging section including a branching section that branches the flow path into a first branching flow path and a second branching flow path, and a merging section that merges the first branching flow path and the second branching flow path into one, a cross-sectional area of ​​the second branch flow path is smaller than a cross-sectional area of ​​the first branch flow path; The second branch flow path has a first portion having a predetermined depth within the second branch flow path and a second portion having a depth different from the depth of the first portion. Base.

3. A plate-shaped base having a pair of main surfaces and a flow path through which a refrigerant flows, the flow path has at least one branching and merging section including a branching section that branches the flow path into a first branching flow path and a second branching flow path, and a merging section that merges the first branching flow path and the second branching flow path into one, a cross-sectional area of ​​the second branch flow path is smaller than a cross-sectional area of ​​the first branch flow path; The depth of the second branch flow path is smaller than the depth of the first branch flow path. Base.

4. A base according to claim 2 or claim 3, The first branch flow path and the second branch flow path are opposed to each other. Base.

5. The base according to any one of claims 1 to 3, The flow path has a plurality of the branching and merging portions. Base.

6. A holding device, a plate-like portion having a placement surface on which an object is placed; a base supporting the plate-shaped portion; and The base is the base according to any one of claims 1 to 3. holding device.

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