Heat exchanger and wafer holding board

Abstract

To provide a heat exchanger and a wafer holding board capable of efficient heat exchange.SOLUTION: A heat exchanger 100 includes: a base body 2 on which a wafer 10 can be placed; a coolant passage 5 formed in the inside of the base body 2, a coolant being flown in the coolant passage; and a metal porous body 6 arranged in the coolant passage 5. A wafer holding board 1 includes: a disc-like base body 2 having an upper surface 2U on which the wafer 10 is placed; a coolant passage 5 formed in the inside of the base body 2, a coolant being flown in the coolant passage; and a metal porous body 6 arranged in the coolant passage 5.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a heat exchanger and a wafer holder. [Background technology]

[0002] Patent Document 1 discloses a wafer prober equipped with a substrate mounting stage. The wafer prober is an inspection device that controls the temperature of a semiconductor wafer on which circuits are formed to a predetermined temperature and measures the electrical performance of each chip before cutting the wafer into individual chips. This measurement of electrical performance detects defective chips. During inspection, the wafer is heated by a heater to reproduce the chip mounting environment, and is cooled using a heat exchanger. After heating, the wafer is quickly cooled using the heat exchanger.

[0003] The substrate mounting table disclosed in Patent Document 1 includes a disk-shaped chuck top supported by a cylindrical support. The chuck top is a base on which a wafer is placed. An inlet and an outlet for a coolant are provided on the outer periphery of the base. An outward path for the coolant connected to the inlet and a return path for the coolant connected to the outlet are provided inside the base. The outward path is a spiral flow path extending from the outer periphery of the base toward the inner periphery. The return path is a spiral flow path extending from the inner periphery of the base toward the outer periphery. Such a base functions as a heat exchanger. That is, the wafer placed on the upper surface of the base is cooled by circulating the coolant through the flow path. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-212775 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the heat exchanger described in Patent Document 1, the contact area between the coolant and the substrate is secured by circulating the coolant through a spiral flow path, and the wafer can be cooled. However, in consideration of shortening the inspection time, more efficient heat exchange is desired. On the other hand, in order to increase the contact area between the coolant and the inner surface of the flow path, it is necessary to lengthen the flow path or to complicate the flow path shape, which requires fine and high-precision processing. Therefore, a heat exchanger that is easy to process and assemble is desired.

[0006] An object of the present disclosure is to provide a heat exchanger capable of more efficient heat exchange, and another object of the present disclosure is to provide a wafer holder capable of efficiently cooling a wafer. [Means for solving the problem]

[0007] The heat exchanger of the present disclosure comprises a base on which an object is placed, a refrigerant flow path formed inside the base and through which a refrigerant flows, and a porous metal body disposed in the refrigerant flow path. Effect of the Invention

[0008] The heat exchanger of the present disclosure allows for more efficient heat exchange. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view of a wafer holder including a heat exchanger according to a first embodiment. [Diagram 2] FIG. 2 is a schematic bottom view of a first member constituting a base of the wafer holder according to the first embodiment. [Diagram 3] FIG. 3 is a partial cross-sectional view of a base of the wafer holder according to the first embodiment. [Figure 4] FIG. 4 is a graph showing the simulation results of the test example. [Diagram 5] FIG. 5 is a schematic diagram of a test machine in a test example. [Figure 6] FIG. 6 is a schematic plan view showing the arrangement of the metallic porous body in the testing machine of FIG. [Figure 7] FIG. 7 is a graph showing the test results of the test examples. [Figure 8] FIG. 8 is a partially enlarged photograph of the porous metal body placed in the testing machine of FIG. [Figure 9] FIG. 9 is a partially enlarged photograph of the grooved plate in which the metal porous body is disposed in the testing machine of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Description of the embodiments of the present disclosure] First, the embodiments of the present disclosure will be listed and described.

[0011] <1> A heat exchanger according to an embodiment includes a base on which an object is placed, a refrigerant flow path formed inside the base and through which a refrigerant flows, and a porous metal body disposed in the refrigerant flow path.

[0012] By disposing the metal porous body in the refrigerant flow path, a heat transfer path is formed between the refrigerant flowing through the refrigerant flow path and the metal porous body, and also between the inner circumferential surface of the refrigerant flow path and the metal porous body. As a result, the metal porous body promotes heat exchange between the refrigerant and the base. The heat of an object placed on the base is efficiently transferred to the refrigerant, and the heat is discharged to the outside of the base together with the refrigerant. Therefore, the object is efficiently cooled.

[0013] The heat exchanger can be manufactured by the simple process of arranging a porous metal body in a refrigerant flow path, and therefore does not require the provision of a complex and long flow path inside the base.

[0014] <2> the above <1> In the heat exchanger described in the above, the porosity of the metal porous body may be 90% or more and 98% or less.

[0015] If the porosity of the metal porous body is 90% or more, i.e., if the solid portion of the metal porous body is small, the metal porous body is less likely to impede the flow of the refrigerant in the refrigerant flow path, and the increase in pressure loss of the refrigerant is easily suppressed. As a result, the flow rate of the refrigerant is less likely to decrease, and heat exchange between the base and the refrigerant is easily performed. If the porosity of the metal porous body is 90% or more, it is easy to ensure a flow space for the refrigerant, and it is easy to ensure a sufficient heat transfer path between the inner surface of the refrigerant flow path and the metal porous body. In addition, a metal porous body with a porosity of 98% or less has mechanical strength that makes it difficult to deform due to the pressure of the refrigerant. Therefore, the flow state of the refrigerant in the refrigerant flow path is stable.

[0016] <3> the above <1> or <2> In the heat exchanger described in the above, the metal porous body may have a three-dimensional network structure.

[0017] In a metal porous body having a three-dimensional network structure, the metal skeleton is connected three-dimensionally, and sufficient heat transfer paths are easily formed. Furthermore, by forming a metal porous body with a three-dimensional network structure, it is easy to obtain a metal porous body with high porosity.

[0018] <4> the above <1> from <3> In the heat exchanger according to any one of the above, the metal porous body may be disposed in an area that occupies 50% or more of the length of the refrigerant flow path.

[0019] By disposing the metal porous body in an area that occupies 50% or more of the length of the coolant flow path, heat exchange between the base and the coolant is easily promoted, and as a result, an object placed on the upper surface of the base is efficiently cooled.

[0020] <5> the above <1> from <4> In the heat exchanger described in any one of the above, a cross section of the refrigerant flow path may have a shape having at least one corner, and a part of the metal porous body may be arranged so as to be in contact with the corner.

[0021] In the corners where no porous metal body is disposed, a large gap is formed, and the coolant flows more easily in the corners than in the corners where a porous metal body is disposed. By disposing a part of the porous metal body so that it contacts the corners of the coolant flow path, a large gap through which the coolant can flow easily is not formed in the corners. As a result, the amount of coolant discharged to the outside of the base without sufficiently absorbing the heat of the base can be reduced.

[0022] <6> the above <5> In the heat exchanger described in the above, the metal porous body may have a fused cut surface facing an inner circumferential surface of the refrigerant flow path.

[0023] The porous metal body is cut by laser or wire electric discharge machining to form a molten cut surface on the porous metal body. Shear drops that occur during machining are unlikely to occur at the edge of the molten cut surface. Therefore, the corners of the porous metal body, including the edge of the molten cut surface, are likely to be positioned so as to contact the corners of the coolant flow path.

[0024] <7> the above <1> from <6> In the heat exchanger according to any one of the above items 1 to 5, a main component of the metal porous body may be nickel or copper.

[0025] Nickel and copper have excellent thermal conductivity. A metal porous body mainly composed of nickel or copper can easily promote heat exchange between the substrate and the refrigerant. Therefore, an object placed on the substrate can be efficiently cooled.

[0026] <8> A wafer holder according to an embodiment of the present invention comprises a disk-shaped base having an upper surface on which a wafer is placed, a coolant flow path formed inside the base through which a coolant flows, and a porous metal body disposed in the coolant flow path.

[0027] By disposing the metal porous body in the coolant flow path, a heat transfer path is formed between the coolant flowing through the coolant flow path and the metal porous body, and a heat transfer path is also formed between the inner peripheral surface of the coolant flow path and the metal porous body. As a result, the metal porous body promotes heat exchange between the coolant and the base. Therefore, the wafer placed on the base is efficiently cooled in a short time.

[0028] <9> the above <8> In the wafer holder described in 1. above, the metal porous body may have a three-dimensional network structure, and the porosity of the metal porous body may be 90% or more and 98% or less.

[0029] In a metal porous body having a three-dimensional network structure, the metal skeleton is connected three-dimensionally, and sufficient heat transfer paths are easily formed. Furthermore, by forming a metal porous body with a three-dimensional network structure, it is easy to obtain a metal porous body with high porosity.

[0030] If the porosity of the metal porous body is 90% or more, i.e., if the solid portion of the metal porous body is small, the metal porous body is less likely to impede the flow of the refrigerant in the refrigerant flow path, and an increase in the pressure loss of the refrigerant is easily suppressed. As a result, the flow rate of the refrigerant is less likely to decrease, and heat exchange between the base and the refrigerant is likely to be performed smoothly. If the porosity of the metal porous body is 98% or less, a sufficient heat transfer path between the inner surface of the refrigerant flow path and the metal porous body is easily secured. In addition, a metal porous body with a porosity of 98% or less has mechanical strength that makes it difficult to deform due to the pressure of the refrigerant. Therefore, the flow state of the refrigerant in the refrigerant flow path is stable.

[0031] <10> the above <8> or <9> In the wafer holder described in the above, the main component of the porous metal body may be nickel or copper.

[0032] Nickel and copper have excellent thermal conductivity. A metal porous body mainly composed of nickel or copper can easily promote heat exchange between the substrate and the coolant. Therefore, the wafer placed on the substrate can be efficiently cooled.

[0033] <11> the above <8> from <10> The wafer holder described in any one of the above items may further include a heater disposed inside or on the lower surface of the base.

[0034] The heater heats the base, thereby heating the wafer placed on the top surface of the base, so that the electrical performance of the heated wafer can be inspected in a wafer inspection process.

[0035] [Details of the embodiment of the present disclosure] In the following embodiment, a wafer holder 1, which is a type of heat exchanger 100, will be described with reference to the drawings. The wafer holder 1 in this example is used in a wafer prober. The wafer prober is an inspection device that measures the electrical performance of each chip while controlling the temperature of a semiconductor wafer 10 on which circuits are formed at a predetermined temperature before cutting the wafer 10 into individual chips. The bold arrow in FIG. 2 indicates the direction in which the coolant flows. The same reference numerals in the figures indicate the same or equivalent parts. The size of the members shown in each drawing is expressed for the purpose of clarifying the description and does not necessarily represent the actual dimensions. Note that the present invention is not limited to these examples, but is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0036] <Embodiment 1> The wafer holder 1 shown in Fig. 1 comprises a base 2, a support 20, a heater 21, and a support structure 3. The base 2 has an upper surface 2U on which a wafer 10 is placed, and a lower surface 2D opposite the upper surface 2U. The support structure 3 supports the base 2 from below. Fig. 1 shows a schematic cross section of the wafer holder 1 cut along a plane along the thickness direction of the base 2. The thickness direction of the base 2 is perpendicular to the upper surface 2U of the base 2, and is the direction from the upper surface 2U toward the lower surface 2D. Each component will be described in detail below.

[0037] ≪Base≫ The base 2 is a member through which a coolant for cooling the wafer 10 flows. The base 2 in this example also functions as a chuck top for adsorbing the wafer 10. The base 2 is provided with a vacuum path 4 and a coolant flow path 5. These paths will be described later in separate sections.

[0038] The overall shape of the base 2 is a shape that matches the shape of the wafer 10, and is usually configured in a disk shape. The diameter of the top surface 2U of the base 2 is long enough to leave some space around the wafer 10 when it is placed on it. The diameter of the top surface 2U is designed to match the size of the wafer 10 to be placed on the top surface 2U. There are various standards for the size of the wafer 10, ranging from 2 inches (about 50 mm) to 12 inches (about 300 mm) in diameter, with 18 inches (about 450 mm) also being envisioned in the future. Currently, the size of the base 2 that is mainly used industrially is a diameter of the top surface 2U of 100 mm or more and 400 mm or less.

[0039] The thickness of the base 2 is, for example, 15 mm or more and 30 mm or less. If the thickness of the base 2 is 15 mm or more, the rigidity of the base 2 is easily ensured, and there is a high degree of freedom in the design of the vacuum path 4 and the refrigerant flow path 5 described later. If the thickness of the base 2 is 30 mm or less, the heat capacity of the base 2 is likely to be small. Therefore, the efficiency and responsiveness of heating by the heater 21 and cooling by the refrigerant described later are likely to be high. The thickness of the base 2 is furthermore 15 mm or more and 20 mm or less, particularly 16 mm or more and 18 mm or less.

[0040] The base 2 can be made of a metal, nonmetal, or a composite of metal and nonmetal, which have excellent thermal conductivity. The higher the thermal conductivity of the material of the base 2, the better. The metal can be, for example, copper, copper alloy, silver, silver alloy, aluminum, or aluminum alloy. In particular, copper or copper alloy, which have excellent thermal conductivity, is preferable. The nonmetal can be, for example, silicon or ceramics. The ceramic can be, for example, aluminum nitride or silicon carbide. The composite can be, for example, a composite of silicon and silicon carbide, a composite of aluminum and silicon carbide, or a composite of aluminum, silicon, and silicon carbide. The material of the base 2 in this example is oxygen-free copper.

[0041] The thermal conductivity of the material constituting the substrate 2 is, for example, 100 W / m·K or more. The thermal conductivity may further be 200 W / m·K or more, 300 W / m·K or more, and particularly 400 W / m·K or more. The thermal conductivity of aluminum is approximately 230 W / m·K, that of copper is approximately 400 W / m·K, and that of silver is approximately 420 W / m·K. The thermal conductivity of silicon carbide is approximately 200 W / m·K, and that of aluminum nitride is approximately 150 W / m·K.

[0042] The base 2 may be subjected to a surface treatment. The surface treatment is, for example, plating. Specific examples of plating are Ni (nickel) plating or Ni-P (phosphorus) plating. The plating method is, for example, electrolytic plating or electroless plating. The surface treatment in this example is Ni-P plating by electroless plating. When copper containing oxygen-free copper is used as the base 2, it is preferable to perform Ni plating or Ni-P plating. Since copper is likely to diffuse into silicon, which is a constituent material of the wafer 10, the diffusion can be suppressed by performing Ni plating or Ni-P plating. As a result, the reliability of the device obtained from the wafer 10 can be ensured. The area where the surface treatment is performed includes the upper surface 2U of the base 2, which is the upper surface of the wafer 10.

[0043] The base 2 in this example is formed by joining a disk-shaped first member 2A and a disk-shaped second member 2B. A spiral groove 2G is formed on the surface of the first member 2A that is joined to the second member 2B. The space surrounded by the inner circumferential surface of the groove 2G and the upper surface of the second member 2B constitutes a refrigerant flow path 5, which will be described later.

[0044] ≪Support≫ The support 20 is a member for suppressing the occurrence of warping of the base 2 due to heat during inspection of the wafer 10. The support 20 may be provided as necessary and is not an essential member. In the absence of the support 20, the leg member 30 described below supports the base 2. If the support 20 is provided, the wafer holder 1 can be made to be less likely to deform due to the force applied from the upper surface 2U. In this example, the support 20 is in close contact with the lower surface 2D of the base 2. The base 2 and the support 20 can be brought into close contact with each other by fastening screws or by vacuum suction. The vacuum suction is performed, for example, by forming a vacuum flow path on the upper surface of the support 20. By using vacuum suction, elements such as fastening screws are not required, the base 2 can be easily heated uniformly, and the flatness of the upper surface 2U can be easily maintained. By bringing the base 2 and the support 20 into close contact with each other, the rigidity of the entire wafer holder 1 can be increased. The overall shape of the support 20 is a shape that matches the shape of the base 2, and in this example, it is a disk shape. The material of the support 20 is, for example, ceramics or a composite material of ceramics and metal. The ceramics is, for example, alumina, mullite alumina, mullite, cordierite, steatite, silicon nitride, or silicon carbide. Since ceramics have high rigidity, if the support 20 is made of ceramics, it is easy to suppress warping of the base 2.

[0045] <Heater> The heater 21 is a unit for heating the base 2, thereby heating the wafer 10 placed on the upper surface 2U of the base 2 to a predetermined temperature. In this example, the heater 21 is disposed on the lower surface of the support 20. Unlike this example, the heater 21 may be disposed inside the base 2. The heater 21 includes, for example, a disk-shaped heating element. The heating element is, for example, a resistance heating element.

[0046] The heater 21 in this embodiment may have one heating element or may have multiple independent heating elements. Each heating element partially heats the base 2. A plurality of heating zones, each of which is independent of the other, are formed on the base 2 in a top view by each of the multiple heating elements, which are independent of each other. The heating zones are virtual regions.

[0047] <Vacuum route> The base 2 in this example is provided with a vacuum path 4 for vacuum-attaching the wafer 10 to the upper surface 2U. The vacuum path 4 sucks air from the vicinity of the upper surface 2U, and adsorbs the wafer 10 to the upper surface 2U without any gaps. By adsorbing the wafer 10 to the upper surface 2U, the wafer 10 can be heated or cooled evenly. Unlike this example, the wafer 10 may be adsorbed to the upper surface 2U by an electrostatic chuck. In that case, the vacuum path 4 is not necessary.

[0048] The vacuum path 4 in this example includes a horizontal hole 4h, a vertical hole 4v, and an annular groove 4r. The horizontal hole 4h is a hole extending in a direction along the upper surface 2U, and is disposed inside the base body 2. The horizontal hole 4h has a first end disposed inside the base body 2 and a second end disposed on the side surface 2C of the base body 2. The first end is a closed end. The second end is an open end. A vacuum pump is connected to the open end by a joint or hose (not shown). The vertical hole 4v is connected to the first end of the horizontal hole 4h. The vertical hole 4v is a short hole connecting the horizontal hole 4h and the annular groove 4r. The vertical hole 4v extends in the thickness direction of the base body 2. The annular groove 4r is a plurality of annular grooves provided coaxially on the upper surface 2U. FIG. 1 shows a cross section of the annular groove 4r.

[0049] By operating the vacuum pump connected to the horizontal hole 4h, the inside of the vacuum path 4 becomes negative pressure. As a result, air near the upper surface 2U is sucked through the annular groove 4r, flows from the vertical hole 4v to the horizontal hole 4h, and is exhausted from the side surface 2C of the base 2. As a result, the wafer 10 placed on the upper surface 2U is vacuum-adsorbed to the upper surface 2U. The warp of the vacuum-adsorbed wafer 10 is corrected, and the wafer 10 is in approximate surface contact with the upper surface 2U.

[0050] <Refrigerant flow path> The refrigerant flow path 5 is formed inside the base 2. More specifically, the refrigerant flow path 5 is formed between the lower surface of the first member 2A and the upper surface of the second member 2B that constitute the base 2. FIG. 2 is a plan view of the lower surface of the first member 2A. In this example, as shown in FIG. 2, a spiral groove 2G is formed on the lower surface of the first member 2A, and the refrigerant flow path 5 is formed by a space surrounded by the inner circumferential surface of the groove 2G and the upper surface of the second member 2B. The refrigerant flow path 5 includes an outward path 5B that is connected to the inlet 5A and a return path 5C that is connected to the outlet 5D. The inlet 5A is an introduction path for the refrigerant. The inlet 5A extends linearly from a predetermined position on the side surface 2C of the base 2 toward the center of the base 2 and connects to the outward path 5B. The outward path 5B is a spiral flow path that connects to the end of the inlet 5A and rotates from the outer periphery of the base 2 to approach the center. The return path 5C is a spiral flow path that turns from the center of the base 2 to approach the outer periphery. The return path 5C turns in the opposite direction to the outward path 5B. The outlet 5D is a discharge path for the refrigerant. The outlet 5D is connected to the end of the return path 5C and extends linearly toward the side surface 2C of the base 2. In this example, a refrigerant introduction pipe 7A is fitted into the inlet 5A, and a refrigerant discharge pipe 7D is fitted into the outlet 5D.

[0051] The refrigerant flows into the refrigerant flow path 5 from the inlet 5A of the refrigerant flow path 5, circulates around the refrigerant flow path 5, and is discharged from the outlet 5D. In this example, the number of the refrigerant flow path 5 is one, but there may be more than one. The multiple refrigerant flow paths 5 may be arranged on the same plane, or each of the multiple refrigerant flow paths 5 may be arranged on a different plane.

[0052] The coolant is not particularly limited as long as it does not substantially react with the base 2. The coolant may be a gas coolant or a liquid coolant. By circulating the coolant through the coolant flow path 5, the entire base 2 is rapidly cooled, and the wafer 10 placed on the upper surface 2U of the base 2 is also rapidly cooled.

[0053] The coolant flow path 5 is not limited to a spiral flow path, but may be, for example, a meandering flow path that is folded back multiple times.

[0054] <Porous metal body> A metal porous body 6 is disposed in the coolant flow passage 5. In the drawings of this example including FIG. 2, the metal porous body 6 is indicated by cross-hatching. By disposing the metal porous body 6 in the coolant flow passage 5, a heat transfer path is formed between the coolant flowing through the coolant flow passage 5 and the metal porous body 6, and a heat transfer path is also formed between the inner circumferential surface of the coolant flow passage 5 and the metal porous body 6. This metal porous body 6 promotes heat exchange between the base 2 and the coolant at the location where the metal porous body 6 is disposed. Therefore, the heat of the wafer 10 is efficiently transferred to the coolant and is discharged to the outside of the base 2 together with the coolant. Therefore, the wafer 10 is efficiently cooled.

[0055] The metal porous body 6 has, for example, a plurality of pores inside while maintaining a certain shape. The metal porous body 6 has, for example, a three-dimensional mesh structure. The photograph of FIG. 8 relating to a test example described later shows a metal porous body 6 having a three-dimensional mesh structure. As shown in FIG. 9, in the metal porous body 6 having a three-dimensional mesh structure, the skeleton 6B made of metal is three-dimensionally connected, and heat transfer is sufficiently ensured. A specific example of the metal porous body 6 having a three-dimensional mesh structure is Celmet. Celmet is a registered trademark of Sumitomo Electric Industries, Ltd. Alternatively, the metal porous body 6 may be a metal foam or a punched metal. These metal porous bodies 6 are unlikely to deform or move due to the pressure of the refrigerant.

[0056] The porosity of the porous metal body 6 is, for example, 50% or more. The porosity is the ratio of the volume of the void space to the total volume of the porous metal body 6. The porosity of the porous metal body 6 is calculated by the formula [1-{M / (V×d)}]×100. The symbol M is the mass (g) of the porous metal body 6, and the symbol V is the volume (cm) of the external shape of the porous metal body. 3 ), and the symbol d is the density (g / cm 3 If the porosity of the porous metal body 6 is 50% or more, a heat transfer path between the base 2 and the porous metal body 6 and a heat transfer path between the refrigerant and the porous metal body 6 are ensured in the refrigerant flow passage 5, and heat exchange between the base 2 and the refrigerant is easily promoted.

[0057] Here, when the porosity of the metal porous body 6 is low, the pressure loss of the refrigerant flowing through the refrigerant flow passage 5 increases. In order to promote more efficient heat exchange between the base 2 and the refrigerant, the porosity of the metal porous body 6 is, for example, 90% or more and 98% or less. If the porosity of the metal porous body 6 is 90% or more, the ratio of pores in the metal porous body 6 is sufficiently large, the flow of the refrigerant in the refrigerant flow passage 5 is not easily hindered, and the increase in the pressure loss of the refrigerant in the refrigerant flow passage 5 is easily suppressed. As a result, the flow rate of the refrigerant in the refrigerant flow passage 5 is not easily decreased, and the heat exchange between the base 2 and the refrigerant is easily performed smoothly. If the porosity of the metal porous body 6 is 98% or less, the heat transfer path between the inner surface of the refrigerant flow passage 5 and the metal porous body 6 is easily secured sufficiently. In addition, the metal porous body 6 with a porosity of 98% or less has mechanical strength that is not easily deformed by the pressure of the refrigerant. Therefore, the flow state of the refrigerant in the refrigerant flow passage 5 is stable. The porosity of the metal porous body 6 may be 93% or more and 98% or less, 95% or more and 98% or less, or 96% or more and 97% or less.

[0058] For example, as shown in FIG. 3, the metal porous body 6 is a member having a cross-sectional shape that is almost the same as the cross-sectional shape of the refrigerant flow path 5. In this case, by arranging the metal porous body 6 in the refrigerant flow path 5, the metal porous body 6 is arranged over the entire cross section of the refrigerant flow path 5. By arranging the metal porous body 6 over the entire cross section of the refrigerant flow path 5, heat exchange between the metal porous body 6 and the refrigerant is efficiently performed. In addition, a plurality of sheet-like metal porous bodies 6 may be stacked and arranged in the refrigerant flow path 5. In this case, by arranging the metal porous body 6 over the entire cross section of the refrigerant flow path 5, heat exchange between the metal porous body 6 and the refrigerant is efficiently performed. The metal porous body 6 may be compressed in the process of being arranged in the refrigerant flow path 5. The porosity of the metal porous body 6 having a three-dimensional network structure does not decrease much even when the metal porous body 6 is compressed. For example, even if the metal porous body 6 having a porosity of 98% before compression is compressed to half its thickness, the porosity of the metal porous body 6 after compression is 90% or more.

[0059] The specific surface area of ​​the metal porous body 6 is, for example, 250 m 2 / m 3 More than 5800m 2 / m 3The specific surface area is the surface area per unit volume. 2 / m 3 If the specific surface area is equal to or greater than 500 m, the contact area between the inner circumferential surface of the substrate 2 and the porous metal body 6, and the contact area between the porous metal body 6 and the refrigerant, can be easily ensured. 2 / m 3 More than 850m 2 / m 3 More than 1250m 2 / m 3 More than 1850m 2 / m 3 More than 2800m 2 / m 3 or above, or 3750m 2 / m 3 More than 5800m is acceptable. 2 / m 3 If the specific surface area of ​​the porous metal body 6 is within the range of, for example, 1850 m2, the size of each pore formed by the skeleton 6B is not too small, and the flow of the refrigerant is not easily hindered. 2 / m 3 More than 5800m 2 / m 3 Below, 2800m 2 / m 3 More than 5800m 2 / m 3 or less than 3750m 2 / m 3 More than 5800m 2 / m 3 It may be the following.

[0060] The metal porous body 6 having a three-dimensional network structure is modeled as a regular dodecahedron in which each pore is surrounded by 12 regular pentagons. In this modeled metal porous body 6, the diameter of the sphere circumscribing the regular dodecahedron is the pore diameter. The average pore diameter of the metal porous body 6 is, for example, 0.45 mm or more and 0.55 mm or less. If the average pore diameter is 0.45 mm or more, the refrigerant easily passes through the metal porous body 6. If the average pore diameter is 0.55 mm or less, the contact area between the metal porous body 6 and the inner surface of the refrigerant flow path 5 is easily secured. The average pore diameter of the metal porous body 6 can be calculated by observing the surface of the metal porous body 6 with a microscope, measuring the number of pores intersecting an arbitrarily drawn 1-inch (25.4 mm) straight line as the number of cells, and calculating the average pore diameter = 25.4 mm / number of cells.

[0061] The main component of the constituent metal of the metal porous body 6 is, for example, nickel or copper. The main component is the component that is contained in the largest amount among the constituent metals of the metal porous body 6. When the content of the constituent metals of the metal porous body 6 is taken as 100 mass%, the content of the main component is more than 50 mass%. The content of the main component in the constituent metals of the metal porous body 6 may be 70 mass% or more, 90 mass% or more, or may be 100 mass%. Since copper has excellent thermal conductivity, if the main component of the metal porous body 6 is copper, the base 2 can be cooled quickly.

[0062] As shown in FIG. 2, the temperature of the portion of the base 2 where the metal porous body 6 is arranged is likely to drop quickly. When cooling the entire base 2, the metal porous body 6 may be arranged in an area of ​​50% or more of the length of the refrigerant flow path 5. The length of the refrigerant flow path 5 is the length from the inlet 5A to the outlet 5D along the refrigerant flow path 5. The metal porous body 6 may be arranged in one area along the refrigerant flow path 5, or may be arranged in a plurality of locations of the refrigerant flow path 5 in a dispersed manner. The larger the area where the metal porous body 6 is arranged, the higher the effect of cooling the entire base 2. The metal porous body 6 may be arranged in an area of ​​60% or more, 70% or more, 80% or more, or 90% or more of the length of the refrigerant flow path 5. In this example, the metal porous body 6 is arranged in the entire portion of the refrigerant flow path 5 except for the portion where the inlet pipe 7A and the outlet pipe 7D are fitted. Here, the refrigerant flows easily in the portion where the metal porous body 6 is not arranged. Therefore, by having the refrigerant flow passage 5 in a portion where the metal porous body 6 is not arranged, the pressure loss of the refrigerant in the entire refrigerant flow passage 5 can be reduced.

[0063] When cooling a portion of the base 2 that is particularly likely to become hot, the metal porous body 6 may be disposed only in that portion. In this case, the region in which the metal porous body 6 is disposed may be less than 50% of the length of the coolant flow path 5.

[0064] The cross section of the refrigerant flow channel 5 in this example is rectangular having four corners 50 as shown in FIG. 3. The corners 50 include the intersections of the inner circumferential surfaces of two adjacent inner circumferential surfaces 51, 51 in the cross section of the refrigerant flow channel 5 and a portion of a predetermined length from the intersections on the inner circumferential surface 51. The predetermined length here is the same as the average pore diameter of the metal porous body 6. In this example, a part of the metal porous body 6 is disposed so as to contact each corner 50. More specifically, when the refrigerant flow channel 5 is observed from a direction perpendicular to the cross section of the refrigerant flow channel 5, a skeleton 6B (see FIG. 8) of a part of the metal porous body 6 contacts the corners 50. FIG. 9 is a photograph showing the arrangement of the metal porous body 6 in the refrigerant flow channel 5 shown in a test example described later. As shown in FIG. 9, the cut end of the skeleton 6B of the metal porous body 6 contacts the inner circumferential surface 51 of the refrigerant flow channel 5. In other words, "the skeleton 6B contacts the corners 50" means that the ends of the cut skeleton 6B are discretely in contact with the corners 50. The interval at which the skeleton 6B contacts the corners 50 is determined by the fineness of the skeleton 6B of the porous metal body 6.

[0065] Since a part of the porous metal body 6 is disposed in contact with the corner 50 of the refrigerant flow path 5, a large gap through which the refrigerant can easily flow is not formed at the corner 50. As a result, the amount of refrigerant discharged from the base 2 without sufficiently absorbing heat from the base 2 can be reduced.

[0066] The metal porous body 6 is processed to match the shape of the refrigerant flow path 5. When the metal porous body 6 is cut with a cutter or the like, shear drops are generated on the cut surface of the metal porous body 6. If a corner 60 of the metal porous body 6 with shear drops is disposed at a corner 50 of the refrigerant flow path 5, a large gap through which the refrigerant can easily flow is likely to be formed at the corner 50. In contrast, when the metal porous body 6 is cut by laser or wire electric discharge machining, a molten cut surface 61 is formed on the metal porous body. Shear drops are unlikely to be generated on the molten cut surface 61. If the metal porous body 6 is disposed in the refrigerant flow path 5 so that the molten cut surface 61 faces the inner circumferential surface 51 of the refrigerant flow path 5, a large gap through which the refrigerant can easily flow is unlikely to be formed at the corner 50.

[0067] ≪Support structure≫ As shown in FIG. 1, the support structure 3 includes a leg member 30 and a base plate 31. The leg member 30 is a member that supports the base body 2 on the base plate 31. When the support body 20 is present, the leg member 30 supports the support body 20 on the base plate 31. The leg member 30 has a shape of, for example, a columnar or cylindrical shape. The columnar or cylindrical leg member 30 supports the support body 20 or the base body 2 by penetrating a hole provided in the heater 21. The outer diameter of the columnar or cylindrical leg member 30 is sufficiently smaller than the outer diameter of the support body 20 or the outer diameter of the base body 2. By using the columnar or cylindrical leg member 30, the contact area between the leg member 30 and the support body 20 or the contact area between the leg member 30 and the base body 2 is reduced. This suppresses heat conduction to the base plate 31 via the leg member 30, and maintains the thermal uniformity of the base body 2. Furthermore, by using the columnar or cylindrical leg member 30, a space can be formed between the heater 21 and the base plate 31. This space contributes to heat insulation between the base plate 31 and the substrate 2. The leg member 30 in this example is a cylindrical body. It is preferable to provide a plurality of leg members 30 so as to support the substrate 2 or the support body 20 in a well-balanced manner. The material of the leg member 30 is, for example, any one of alumina, mullite alumina, mullite, cordierite, steatite, and silicon nitride.

[0068] The base plate 31 is a member that serves as a base for supporting the substrate 2, the support 20, the heater 21, and the leg members 30. The material of this base plate 31 is, for example, alumina, aluminum nitride, silicon carbide, a composite of silicon and silicon carbide, a composite of aluminum and silicon carbide, or a composite of aluminum, silicon, and silicon carbide.

[0069] <Test Example> In the test example, the effect of the porosity of the metal porous body 6 arranged in the coolant flow path 5 on the heat absorbing performance was examined by simulation. The heat absorbing performance is the ability to absorb heat from the base 2.

[0070] In the test example, the influence of the material and porosity of the metal porous body 6 was evaluated based on the improvement rate of the heat absorbing performance. The improvement rate is calculated by (R / R0)×F. "R0" is the thermal conductivity of the refrigerant flow path 5 in which the metal porous body 6 is not disposed. In this case, the thermal conductivity of the refrigerant flow path 5 is equal to the thermal conductivity of the refrigerant in a flowing state. The thermal conductivity of the refrigerant in a flowing state is the value obtained by multiplying the thermal conductivity of the refrigerant in a stationary state by the Nusselt number. "R" is the thermal conductivity of the refrigerant flow path 5 in which the metal porous body 6 is arranged, i.e., the sum of the thermal conductivity of the refrigerant in a flowing state and the thermal conductivity of the metal porous body 6 exposed to the refrigerant in a flowing state. It is calculated by R = {thermal conductivity of the metal porous body 6 exposed to the refrigerant in a flowing state × (1 - (porosity / 100)) + R0 × (porosity / 100)}. "F" is a coefficient that takes into consideration the effect of refrigerant pressure loss caused by the placement of the metal porous body 6 in the refrigerant flow path 5. Specifically, it is a flow rate ratio obtained by dividing the flow rate of the refrigerant flowing through the refrigerant flow path 5 in which the metal porous body 6 is placed by the flow rate of the refrigerant flowing through the refrigerant flow path 5 in which the metal porous body 6 is not placed. The improvement rate is calculated by dividing the thermal conductivity of the refrigerant flow path 5 in which the metal porous body 6 is arranged by the thermal conductivity of the refrigerant flow path 5 in which the metal porous body 6 is not arranged, and multiplying the result by a coefficient F. In other words, the improvement rate is the value of the thermal conductivity of the refrigerant flow path in which the metal porous body 6 is arranged, when the thermal conductivity of the refrigerant flow path 5 in which the metal porous body 6 is not arranged is set to 1. It can be determined that the higher the improvement rate, the higher the heat absorption performance.

[0071] The constituent materials of the porous metal body 6 in the simulation were copper or nickel. The thermal conductivity of copper was 398 W / m·K. The thermal conductivity of nickel was 90 W / m·K. The improvement rate results are shown in the graph in Figure 4. The horizontal axis of the graph is the porosity in units of percent. The porosity is in increments of 0.5%. The vertical axis is the improvement rate of the heat absorption performance, which is unitless. The black circles plot data for the porous metal body 6 made of copper (Cu), and the black diamonds plot data for the porous metal body 6 made of nickel (Ni).

[0072] 4, it was found that the heat absorbing performance is improved by disposing the metal porous body 6 in the refrigerant flow path 5. Furthermore, in the simulation, the higher the thermal conductivity of the metal constituting the metal porous body 6, the higher the heat absorbing performance became.

[0073] Next, the actual improvement rate of the heat absorbing performance was examined by a tester 8 shown in FIG. 5 and FIG. 6. The tester 8 includes a grooved plate 80, a pressing plate 81 that is placed on the grooved plate 80, and a jig 82 that presses the pressing plate 81. The grooved plate 80 and the pressing plate 81 are made of nickel-plated oxygen-free copper. As shown in FIG. 6, a serpentine groove 80g is formed in the grooved plate 80. The space surrounded by the inner circumferential surface of the serpentine groove 80g and the pressing plate 81 functions as the refrigerant flow path 5. A refrigerant inlet pipe 8A is disposed at a first end of the serpentine groove 80g, and a refrigerant outlet pipe 8D is disposed at a second end of the serpentine groove 80g. The refrigerant introduced into the serpentine groove 80g from the inlet pipe 8A in the direction of the thick arrow is discharged from the outlet pipe 8D through the serpentine groove 80g.

[0074] The jig 82 presses the pressing plate 81 against the grooved plate 80. Furthermore, the jig 82 is configured to generate heat when a voltage is applied to it. A temperature sensor is disposed in the jig 82 so that the temperature of the jig 82 can be measured. The jig 82 imitates the wafer 10.

[0075] Reference data was obtained using the tester 8. The reference data is data on the cooling performance in a state where the metal porous body 6 is not disposed in the meandering groove 80g. Specifically, when the jig 82 was applied with 16 W / cm 2 The data was obtained by flowing a coolant through the serpentine groove 80g while applying a power of 16 W / cm2 (watts per square centimeter). The flow rate of the coolant was 2.80 liters per minute. The results of the reference data are shown in the graph in Figure 7. The horizontal axis of Figure 7 is the time elapsed from the start of voltage application. The vertical axis is the measurement result of the temperature sensor of the jig 82, i.e., the temperature of the jig 82. The unit of the vertical axis is degrees Celsius. The temperature of the jig 82 before the start of voltage application was 23°C. As shown in the graph, the temperature of the jig 82 continued to rise from the start of voltage application. Approximately 180 seconds after the start of voltage application, the temperature of the jig 82 stabilized at approximately 39.4°C. The temperature rise from the start of the test was 16.4°C. The jig 82 was supplied with a power of 16 W / cm2. 2Since the temperature of the jig 82 stabilized even though the voltage was continuously applied, it is believed that the coolant was removing heat from the jig 82.

[0076] Next, the cooling performance data of the sample No. 1 in which the metal porous body 6 was arranged in the meandering groove 80g was obtained using the test machine 8. FIG. 8 is a photograph of the metal porous body 6, and FIG. 9 is a partially enlarged photograph of the grooved plate 80 in which the metal porous body 6 was arranged in the meandering groove 80g. The metal porous body 6 was a Celmet made of copper. That is, the metal porous body 6 had a three-dimensional network structure in which a plurality of copper skeletons 6B were three-dimensionally connected. The porosity of the metal porous body 6 was 97%. The metal porous body 6 was arranged at a position shown by the cross-hatching of the two-dot chain line in FIG. 6. As shown in FIG. 9, the skeleton 6B of the metal porous body 6 was arranged so as to contact the corner portion 50 of the refrigerant flow path 5. When the refrigerant was flowed through the meandering groove 80g of the test machine 8 at the same pressure as when the reference data was obtained, the flow rate of the refrigerant was 2.74 liters / min. The data results of the sample No. 1 are shown in the graph of FIG. 7. As shown in the graph, in sample No. 1, the temperature of jig 82 stabilized at 34.1°C about 120 seconds after the start of voltage application. The temperature increase from the start of the test was 12.1°C.

[0077] The results of the actual measurements showed that by placing the porous metal body 6 in the coolant flow path 5, the object to be cooled can be cooled quickly, and furthermore, the temperature of the object to be cooled can be lowered than when the porous metal body 6 is not present.

[0078] The improvement rate of heat absorption performance of sample No. 1 obtained from the actual measurement data is plotted in the graph in Figure 4. The temperature rise range of the reference data divided by the temperature rise range of sample No. 1 is regarded as the improvement rate of heat absorption performance of the actual measurement data. The temperature rise range of the reference data was 16.4°C, and the temperature rise range of the sample with a copper-based ceramic was 12.1°C. The improvement rate of heat absorption performance of sample No. 1 was 16.4 / 12.1=1.335. As shown by the square plot on the right side of the graph in Figure 4, the improvement rate of heat absorption performance of sample No. 1 was almost the same as the improvement rate of heat absorption performance obtained by calculation. [Explanation of symbols]

[0079] 1 Wafer holder 10 Wafers 2 Base 2A First Component 2B Second member 2C side 2D bottom side 2G groove 2U top 20 Support 21 Heater 3 Support structure 30 Leg members 31 Base plate 4 Vacuum Path 4h horizontal hole, 4r annular groove, 4v vertical hole 5 Coolant flow path 5A inlet, 5B outward, 5C return, 5D outlet 50 corner, 51 inner surface 6. Porous Metal 6B Skeleton 60 corner, 61 melted cut surface 7A inlet pipe, 7D discharge pipe 8. Testing Machine 8A inlet pipe, 8D discharge pipe 80 grooved plate, 80g serpentine groove 81 Presser plate 82 Jig 100 heat exchanger

Claims

1. A base on which an object can be placed; a coolant flow path formed inside the base and through which a coolant flows; A metal porous body disposed in the refrigerant flow path. heat exchanger.

2. 2. The heat exchanger according to claim 1, wherein the porosity of the metal porous body is 90% or more and 98% or less.

3. The heat exchanger according to claim 1 or 2, wherein the metal porous body has a three-dimensional network structure.

4. 3. The heat exchanger according to claim 1, wherein the metal porous body is disposed over an area of ​​50% or more of the length of the refrigerant flow path.

5. A cross section of the refrigerant flow path has at least one corner, The heat exchanger according to claim 1 or 2, wherein a portion of the porous metal body is disposed so as to be in contact with the corner portion.

6. The heat exchanger according to claim 5 , wherein the porous metal body has a fused cut surface facing an inner circumferential surface of the refrigerant flow path.

7. 3. The heat exchanger according to claim 1, wherein the main component of the porous metal body is nickel or copper.

8. a disk-shaped base having an upper surface on which a wafer is placed; a coolant flow path formed inside the base and through which a coolant flows; A metal porous body disposed in the refrigerant flow path. Wafer holder.

9. The metal porous body has a three-dimensional network structure, 9. The wafer holder according to claim 8, wherein the porosity of the metal porous body is 90% or more and 98% or less.

10. 10. The wafer holder according to claim 8, wherein the main component of the porous metal body is nickel or copper.

11. 10. The wafer holder according to claim 8, further comprising a heater disposed inside or on a lower surface of the base.

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