Wafer holder

Abstract

To provide a wafer holding table capable of more effectively cooling a wafer.SOLUTION: A wafer holding table comprises a base body as a metal disk. The base body has an upper surface on which a wafer is mounted, and a coolant channel that is provided in an inner part of the base body. A cross section of the base body along a direction vertical to the upper surface includes a plurality of cross sections of the channel. Each of the cross sections of the channel ia cross section vertical to a direction of the flow of the coolant. Each of the cross sections of the channel has a rectangular shape. Each of the cross sections of the channel includes a first side which is parallel to the upper surface and is the closest to the upper surface. A length L1 of the first side and a distance L2 between a first cross section and a second cross section which are adjacent to each other of the plurality of cross sections of the channel satisfy a relationship of 0.3≤(L2 / L1)≤2.5. A distance L3 between the first side and the upper surface and the length L1 satisfy a relationship of (L1 / L3)≤1.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] TECHNICAL FIELD The present disclosure relates to a wafer holder. [Background technology]

[0002] Patent Document 1 discloses a substrate mounting plate. The substrate mounting plate corresponds to the wafer holder in this disclosure. The substrate mounting plate is used in an inspection device, such as a prober, that measures the electrical performance of each semiconductor wafer (hereinafter simply referred to as a "wafer") on which multiple circuits are formed, before the wafer is cut into individual chips. The substrate mounting plate disclosed in Patent Document 1 includes a chuck top supported by a cylindrical support on a disk-shaped base. A coolant flow path is provided inside the chuck top. The semiconductor wafer mounted on the chuck top is cooled by circulating the coolant through the flow path. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-212775 Summary of the Invention [Problem to be solved by the invention]

[0004] As semiconductor integration increases, semiconductors generate more heat during testing. In particular, when testing each chip, heat is concentrated locally within the surface of the semiconductor wafer, causing the temperature of that portion of the wafer to rise. To keep this temperature rise within a desired range, a means of cooling the wafer more efficiently than ever before is needed.

[0005] An object of the present disclosure is to provide a wafer holder that can cool a wafer more efficiently. [Means for solving the problem]

[0006] The wafer holder of the present disclosure comprises: A wafer holder having a base that is a metal disk, the base has an upper surface on which a wafer is placed and a coolant flow path provided inside the base, a cross section of the substrate taken along a direction perpendicular to the upper surface has cross sections of a plurality of the flow channels; Each of the cross sections of the flow path is a cross section perpendicular to the flow direction of the refrigerant, The shape of each cross section of the flow path is rectangular; each of the cross sections of the flow path has a first side parallel to the top surface and closest to the top surface; a length L1 of the first side and a distance L2 between a first cross section and a second cross section adjacent to each other among the cross sections of the plurality of flow paths satisfy a relationship of 0.3≦(L2 / L1)≦2.5; The distance L3 between the first side and the upper surface and the length L1 satisfy the relationship (L1 / L3)≦1. [Effects of the Invention]

[0007] The wafer holder of the present disclosure can cool the wafer more efficiently. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic cross-sectional view of a wafer holder according to an embodiment. [Figure 2] FIG. 2 is an enlarged schematic cross-sectional view of region A in FIG. [Figure 3] FIG. 3 is a cross-sectional schematic diagram illustrating the shape of a flow path in a substrate provided on a wafer holder according to the embodiment. [Figure 4A] FIG. 4A is a diagram illustrating heat exchange between a heat generating element and a refrigerant flowing through a flow path. [Figure 4B] FIG. 4B is a diagram illustrating heat exchange between the heating element and the refrigerant flowing through the flow path. [Figure 4C] FIG. 4C is a diagram illustrating heat exchange between the heat generating element and the refrigerant flowing through the flow path. DETAILED DESCRIPTION OF THE INVENTION

[0009] <<Description of Embodiments of the Present Disclosure>> First, embodiments of the present disclosure will be listed and described.

[0010] (1) A wafer holder according to one aspect of the present disclosure includes: A wafer holder having a base that is a metal disk, the base has an upper surface on which a wafer is placed and a coolant flow path provided inside the base, a cross section of the substrate taken along a direction perpendicular to the upper surface has cross sections of a plurality of the flow channels; Each of the cross sections of the flow path is a cross section perpendicular to the flow direction of the refrigerant, The shape of each cross section of the flow path is rectangular; each of the cross sections of the flow path has a first side parallel to the top surface and closest to the top surface; a length L1 of the first side and a distance L2 between a first cross section and a second cross section adjacent to each other among the cross sections of the plurality of flow paths satisfy a relationship of 0.3≦(L2 / L1)≦2.5; The distance L3 between the first side and the upper surface and the length L1 satisfy the relationship (L1 / L3)≦1.

[0011] The wafer holder described above has a good balance between length L1, distance L2, and distance L3, since the length L1, distance L2, and distance L3 satisfy the above relationship. This facilitates heat exchange between the heating element and the refrigerant. Therefore, the wafer holder described above can cool the wafer more efficiently. Here, the cross section of the flow path refers to the hollow portion of the flow path, i.e., the portion through which the refrigerant flows.

[0012] (2) As one embodiment of the wafer holder, The length L1 and the distance L2 may satisfy the relationship (L2 / L1)≦1.

[0013] In the above configuration, the length L1 and the distance L2 are well balanced, and furthermore, the flow paths are densely arranged, so that the wafer can be cooled more efficiently.

[0014] (3) As one embodiment of the wafer holder, Each of the cross sections of the flow path has a second side perpendicular to the first side, The length L1 and the length L4 of the second side may satisfy the relationship L1≦L4.

[0015] The above configuration can cool the wafer more efficiently even if the cross section of the flow path is a square or a vertically long rectangle.

[0016] (4) As one embodiment of the wafer holder of (1) or (2), Each of the cross sections of the flow path has a second side perpendicular to the first side, The length L1 and the length L4 of the second side may satisfy the relationship L1>L4.

[0017] The above configuration can cool the wafer more efficiently even if the cross section of the flow path has a horizontally long rectangular shape.

[0018] (5) As one embodiment of the wafer holder, the substrate is made of copper or a copper alloy; The diameter of the upper surface is 100 mm or more and 400 mm or less, The area of ​​each of the cross sections of the flow channel is 5 mm 2 That's all, The thickness of the substrate may be 15 mm or more and 30 mm or less.

[0019] In the above embodiment, the diameter of the upper surface is within the above range, so that wafers of various diameters can be placed on the upper surface of the base. In the above embodiment, the area of ​​each cross section of the flow path is within the above range, so that the required flow rate of the refrigerant can be ensured without applying excessive pressure, making it easier to cool the wafer more efficiently. In the above embodiment, the thickness of the base is 15 mm or more, so that it is easier to ensure the rigidity of the base 10. In the above embodiment, the thickness of the base is 30 mm or less, so that it is easier to heat or cool the wafer more efficiently.

[0020] (6) As one embodiment of the wafer holder, The length L1 may be 1 mm or more and 15 mm or less.

[0021] The first edge is the width of the surface of the flow path where heat transferred from the top surface first comes into contact with the coolant. The shorter the length L1 of the first edge, the greater the number of flow paths. A larger number of flow paths also increases the number of paths between the flow paths, thereby increasing the rigidity of the base against downward forces from the top surface. On the other hand, a short length L1 requires a longer length L4, which corresponds to the height of the flow path, to ensure sufficient cross-sectional area for the flow path. This necessitates a larger overall thickness for the base. By ensuring that length L1 is 1 mm or greater, a good balance can be maintained between lengths L1 and L4. Therefore, the above configuration facilitates more efficient cooling of the wafer. The longer the length L1, the easier it is to increase the cross-sectional area of ​​the flow path and the flow rate of the coolant. Furthermore, a longer length L1 facilitates the transfer of heat transferred from the top surface to the coolant at the top surface of the flow path. On the other hand, a longer length L1 increases the distance between the flow paths, which necessitates a longer distance L3 between the top surface and the flow path to ensure the rigidity of the base against downward forces from the top surface. By setting the length L1 to 15 mm or less, it is possible to maintain a good balance between the length L1 and the distance L3.

[0022] (7) As one embodiment of the wafer holder, a support and a temperature adjustment unit provided on the lower surface side of the base, the support is a ceramic disk, The substrate and the support may be vacuum-adsorbed.

[0023] In the above-described embodiment, the substrate can be firmly supported by providing a support. By closely contacting the substrate and the support, the rigidity of the entire wafer holder can be increased. By providing a support, the wafer holder can be made less likely to deform when subjected to a force applied from above. In the above-described embodiment, the temperature adjustment unit can be provided to adjust the temperature of the wafer.

[0024] Details of the embodiments of the present disclosure A wafer holder according to an embodiment of the present disclosure will be described with reference to the drawings. The wafer holder according to the present disclosure can be used as part of a semiconductor manufacturing device. The following description will be given using a wafer holder used in a wafer prober as an example. A wafer prober is an inspection device that measures the electrical performance of a semiconductor wafer with circuits formed thereon while controlling the wafer at a predetermined temperature before cutting the wafer into individual chips. The wafer holder according to an embodiment of the present disclosure is not limited to wafer probers, but can also be used for wafer holders with similar structures for other applications. The same reference numerals in the figures indicate the same objects. The size and positional relationship of components shown in each drawing are depicted for the purpose of clarity and do not necessarily represent the actual dimensional relationship. Directions are indicated by referring to the side on which the wafer is placed as the upper side and the opposite side as the lower side.

[0025] <<Embodiment>> [Wafer holder] A wafer holder 1 according to an embodiment will be described with reference to FIGS. 1 to 3 and 4C. As shown in FIG. 1, the wafer holder 1 according to this embodiment includes a base 10. FIG. 1 schematically shows a cross section of the wafer holder 1 cut along a plane perpendicular to the top surface 10u of the base 10. The top surface 10u of the base 10 is the surface on which a wafer is placed. The base 10 includes a flow path 12 for circulating a coolant. The flow path 12 is provided inside the base 10. One of the features of the wafer holder 1 according to this embodiment is that the base 10 has a specific cross section 10c. The wafer holder 1 according to this embodiment also includes a support structure for the base 10. Each component will be described in detail below.

[0026] [Base] 1, the base 10 is a member through which a refrigerant for cooling the wafer flows. Although not shown, the base 10 of this embodiment also functions as a chuck top that adsorbs the wafer and also functions to adsorb the support 20. The overall shape of the base 10 is shaped to match the shape of the wafer, and is usually formed in a disk shape.

[0027] The diameter of the upper surface 10u is long enough to allow some clearance around the wafer when it is placed on it. The diameter of the upper surface 10u is designed to match the size of the wafer to be placed on the upper surface 10u. Wafer sizes vary in size from 2 inches (approximately 50 mm) to 12 inches (approximately 300 mm) in diameter, with 18 inches (approximately 450 mm) expected in the future. Currently, the size of the substrate 10 that is mainly used industrially is one in which the diameter of the upper surface 10u is between 100 mm and 400 mm.

[0028] The thickness of the substrate 10 is, for example, 15 mm or more and 30 mm or less. If the thickness of the substrate 10 is 15 mm or more, it is easy to ensure the rigidity of the substrate 10 and there is a high degree of freedom in designing the flow path 12. If the thickness of the substrate 10 is 30 mm or less, the size of the entire device, such as a prober, can be made compact. Furthermore, a thin thickness of the substrate 10 tends to reduce the heat capacity of the substrate 10. Therefore, the efficiency and responsiveness of heating by a heater, which will be described later, and cooling by a refrigerant flowing through the flow path 12 tend to be high. The thickness of the substrate 10 is furthermore 15 mm or more and 20 mm or less, and particularly 16 mm or more and 18 mm or less.

[0029] The material of the substrate 10 can be a metal, a nonmetal, or a composite of a metal and a nonmetal, which have excellent thermal conductivity. The higher the thermal conductivity of the material of the substrate 10, the more preferable it is. Examples of metals include copper, copper alloys, silver, silver alloys, aluminum, and aluminum alloys. Copper or copper alloys, which have excellent thermal conductivity, are particularly suitable. Examples of nonmetals include silicon and ceramics. Examples of ceramics include aluminum nitride and silicon carbide. Examples of composites include a composite of silicon and silicon carbide, a composite of aluminum and silicon carbide, and a composite of aluminum, silicon, and silicon carbide. The material of the substrate 10 in this embodiment is oxygen-free copper.

[0030] The thermal conductivity of the material constituting the substrate 10 is preferably 100 W / m·K or higher. This thermal conductivity is more preferably 200 W / m·K or higher, 300 W / m·K or higher, and particularly preferably 400 W / m·K or higher. 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.

[0031] The substrate 10 may be subjected to a surface treatment. This surface treatment may be, for example, plating. Specific examples of plating include Ni plating and Ni-P plating. Plating techniques include electrolytic plating and electroless plating. In this embodiment, the surface treatment is Ni-P plating by electroless plating. When copper containing oxygen-free copper is used for the substrate 10, Ni plating or Ni-P plating is preferable. Because copper easily diffuses into silicon, which is the constituent material of the wafer, Ni plating or Ni-P plating can suppress this diffusion. As a result, the reliability of devices obtained from the wafer can be ensured. The area to be surface-treated preferably includes the upper surface 10u of the substrate 10, which serves as the wafer mounting surface. Additionally, it is desirable to remove surface waviness and roughness from this upper surface 10u after the surface treatment. The waviness and roughness can be removed, for example, by lapping. Removing the waviness and roughness from the upper surface 10u increases the contact area with the wafer to be mounted, facilitating heat transfer from the heated wafer to the substrate 10.

[0032] (flow path) A refrigerant flows through the flow channel 12 shown in FIG. 1. FIG. 1 is a schematic cross-section for illustrative purposes, simply showing a state in which multiple cross sections 12c of the flow channel 12 perpendicular to the flow direction of the refrigerant are arranged side by side. FIG. 3 is a cross-sectional view schematically showing a state in which a portion of the base 10 where the flow channel 12 is present is cut along a plane parallel to the upper surface 10u. The flow channel 12 may be formed, for example, in a spiral shape inside the base 10, which is circular in plan view. The refrigerant flows into the flow channel 12 from the inlet 12i, travels around the flow channel 12, and is discharged from the outlet 12e. The shape of the flow channel 12 is an example for illustrative purposes and is not limited. In this embodiment, there is one flow channel 12, but the number of flow channels 12 is not limited. Multiple flow channels 12 may be provided on the same plane, or the flow channel 12 may be configured to branch or merge internally.

[0033] As shown in FIG. 1, the cross section 10c of the base 10 has multiple cross sections 12c of the flow channels 12. The cross sections 10c are cross sections along a direction perpendicular to the top surface 10u. Each cross section 12c is cross section perpendicular to the refrigerant flow direction. Each cross section 12c has a rectangular shape. In this embodiment, each cross section 12c has the same rectangular shape. As shown in FIG. 2, each cross section 12c has a first side 131, a second side 132, a third side 133, and a fourth side 134. The first side 131 is parallel to the top surface 10u and is the side closest to the top surface 10u. The second side 132 and the third side 133 are perpendicular to the first side 131. That is, the second side 132 and the third side 133 are parallel to each other. The upper end of the second side 132 is connected to the left end of the first side 131. The upper end of the third side 133 is connected to the right end of the first side 131. The fourth side 134 is a side parallel to the first side 131 and is the side closest to the lower surface 10d of the base 10. The left end of the fourth side 134 is connected to the lower end of the second side 132. The right end of the fourth side 134 is connected to the lower end of the third side 133.

[0034] The length L1 and the distance L2 satisfy the relationship 0.3≦(L2 / L1)≦2.5. Furthermore, the length L1 and the distance L3 satisfy the relationship (L1 / L3)≦1. The length L1 is the length of the first side 131. The distance L2 is the shortest distance between the first cross section 121 shown on the left side of FIG. 2 and the second cross section 122 shown on the right side of FIG. 2. The first cross section 121 and the second cross section 122 are adjacent cross sections among the multiple cross sections 12c. In other words, the distance L2 is the distance between the third side 133 of the first cross section 121 and the second side 132 of the second cross section 122. The distance L3 is the shortest distance between the first side 131 and the top surface 10u.

[0035] When the length L1, the distance L2, and the distance L3 satisfy the above relationship, the wafer can be more efficiently cooled by the coolant flowing through the flow path 12. This is because the balance between the length L1, the distance L2, and the distance L3 is good, facilitating heat exchange between the wafer and the coolant. Therefore, the wafer holder 1 of this embodiment is not only suitable for use when the device to be inspected is a device with a low heat generation density, but also suitable for use when the device to be inspected is a device with a high heat generation density. An example of a device with a low heat generation density is a memory. An example of a device with a high heat generation density is an SoC (System on a Chip).

[0036] When testing memory, multiple chips on a wafer are tested simultaneously using a single-contact probe card. On the other hand, when testing SoCs, multiple chips on a wafer are tested individually and sequentially using a multi-contact probe card. The tested chips are heat-generating elements. When testing SoCs, the heat density is high and multiple chips are tested individually and sequentially, so the tested areas of the wafer are likely to generate large amounts of heat locally.

[0037] As described above, the length L1, the distance L2, and the distance L3 satisfy the above relationship, resulting in a good balance between the length L1, the distance L2, and the distance L3. Therefore, heat from the heating element 100 is easily transferred to the refrigerant flowing through the flow path 12 not only through the first surface constituting the first side 131 but also through the second and third surfaces constituting the second and third sides 132 and 133, respectively, and also through the fourth surface constituting the fourth side 134. Therefore, the wafer holder 1 of this embodiment is also suitable for use in cases where multiple chips on a wafer are individually and sequentially tested using a multi-contact probe card. The first surface is the top surface of the flow path 12, the second surface and the third surface are the left and right sides of the flow path 12, respectively, and the fourth surface is the bottom surface of the flow path 12.

[0038] The length L1 and the distance L2 may satisfy the relationship (L2 / L1)≦2, or even the relationship (L2 / L1)≦1. In this case, the length L1 and the distance L2 are well balanced, and the flow paths 12 are arranged more densely, allowing for more efficient cooling of the wafer. The length L1 and the distance L3 may also satisfy the relationship (L1 / L3)≦0.9, particularly (L1 / L3)≦0.8. The length L1 and the distance L3 may also satisfy the relationship 0.2≦(L1 / L3). That is, the length L1 and the distance L3 may satisfy the relationship 0.2≦(L1 / L3)≦1, or even 0.2≦(L1 / L3)≦0.9, particularly 0.2≦(L1 / L3)≦0.8.

[0039] The lengths L1 and L4 satisfy either the relationship L1≦L4 or the relationship L1>L4. The relationship L1≦L4 is satisfied when the cross-section 12c of the flow path 12 is a square or a vertically elongated rectangle. A relatively short length L1, which is the width of the flow path 12, allows for a large number of flow paths 12, i.e., a high density of the flow paths 12. A relatively short length L1 also allows for a large number of paths 12 between adjacent flow paths 12, thereby increasing the rigidity of the base 10. The relationship L1>L4 is satisfied when the cross-section 12c of the flow path 12 is a horizontally elongated rectangle. A relatively long width of the flow path 12 makes it easy to increase the cross-sectional area of ​​the flow path 12 and increase the flow rate of the refrigerant. Furthermore, a long width of the flow path 12 makes it easy to transfer heat transferred from the upper surface 10u to the refrigerant at the upper surface of the flow path 12. By taking these characteristics into consideration, the heat generating element 100 can be cooled more efficiently by the refrigerant flowing through the flow path 12, regardless of whether the shape of the cross section 12c is a square, a vertically long rectangle, or a horizontally long rectangle.

[0040] The area of ​​the cross section 12c is, for example, 5 mm 2 The area of ​​the cross section 12c is calculated by multiplying the length L1 by the length L4. 2 If the area of ​​the cross section 12c is equal to or larger than this, the required flow rate of the coolant can be ensured without applying excessive pressure, and the wafer can be more efficiently cooled by the coolant. 2 The area of ​​the cross section 12c may be 80 mm 2 If the number of cross sections 12c is constant, the total area of ​​the cross sections 12c in the base body 10 is unlikely to become excessively large. Therefore, the rigidity of the base body 10 is unlikely to decrease. 2 Over 80mm 2 The area of ​​the cross section 12c is further increased by 7 mm 2 Over 40mm 2 Below, especially 7mm 2 More than 30mm 2 It may be the following:

[0041] The length L1 may be, for example, 1 mm or more and 15 mm or less. The first side 131 is the width of the first surface, which is the surface of the flow path 12 where heat transferred from the upper surface 10u first comes into contact with the refrigerant. The shorter the length L1 of the first side 131, the more the number of flow paths 12 can be increased. A larger number of flow paths 12 also increases the number of spaces between the flow paths 12, thereby increasing the rigidity of the base 10 against downward forces from the upper surface 10u. On the other hand, if the length L1 is short, the length L4, which corresponds to the height of the flow paths 12, must be increased to ensure the cross-sectional area of ​​the flow paths 12. Therefore, the thickness of the entire base 10 must be increased. If the length L1 is 1 mm or more, the lengths L1 and L4 can be balanced. This makes it easier to cool the wafer more efficiently.

[0042] Furthermore, if the length L1 is 1 mm or more, the distance L3 tends to be relatively long, and thus the rigidity of the upper surface 10u side of the base 10 is unlikely to decrease. Chip inspection is performed by pressing the probes of a probe card against the chip. During inspection, a load is more likely to act locally on the wafer when multiple chips on the wafer are individually and sequentially inspected using a multi-contact probe card, compared to when multiple chips on the wafer are inspected collectively using a single-contact probe card. Since the distance L3 of the base 10 tends to be relatively long, sufficient rigidity against the above-mentioned pressure can be easily ensured. Therefore, the wafer holder 1 of this embodiment can be suitably used even when multiple chips on a wafer are individually and sequentially inspected using a multi-contact probe card, such as when inspecting an SoC.

[0043] The longer the length L1, the easier it is to increase the cross-sectional area of ​​the flow path 12 and the easier it is to increase the flow rate of the refrigerant. Furthermore, when the length L1 is long, the heat transferred from the upper surface 10u is more easily transferred to the refrigerant on the first surface of the flow path 12. On the other hand, when the length L1 is long, the distance between the flow paths becomes long, and it becomes necessary to increase the distance L3 between the upper surface 10u and the flow path 12 in order to ensure the rigidity of the base 10 against the downward force from the upper surface 10u. If the length L1 is 15 mm or less, the length L1 and the distance L3 can be well balanced.

[0044] The length L1 may further be 1 mm or more and 12 mm or less, particularly 1 mm or more and 10 mm or less.

[0045] 4A to 4C, the heat exchange between the heating element 100 and the refrigerant flowing through the flow path 12 will be described. For the length L1, distance L2, and distance L3, refer to FIG. 2 as needed. FIG. 4A shows an example where L1 / L3 satisfies the above-mentioned range, but L2 / L1 does not. FIG. 4B shows an example where L2 / L1 satisfies the above-mentioned range, but L1 / L3 does not. FIG. 4C shows an example where both L2 / L1 and L1 / L3 satisfy the above-mentioned range. The multiple arc-shaped dashed-dotted lines and multiple straight dashed-dotted arrows in FIGS. 4A to 4C indicate how heat from the heating element 100 is transferred. As indicated by the arc-shaped dashed-dotted lines, heat from the heating element 100 is transferred while spreading concentrically from the upper surface 10u of the base 10. Then, the heat from the heating element 100 approaching the vicinity of the cross section 12c is transferred from above to below the base 10, as indicated by the straight dashed two-dot arrow. The hatched areas in Figures 4A to 4C indicate the areas that mainly contribute to heat exchange.

[0046] In the example shown in FIG. 4A, the area that contributes to heat exchange is substantially only each first side 131. In this example, the distance from the upper surface 10u to the cross section 12c closest to the heating element 100 is long. Therefore, heat from the heating element 100 is easily transferred not only to the cross section 12c closest to the heating element 100 but also to the other cross sections 12c. However, in this example, the distance between adjacent cross sections 12c is short. Therefore, little heat flows between adjacent cross sections 12c. Therefore, heat exchange is preferentially performed from each first side 131, and each second side 132, each third side 133, and each fourth side 134 are unlikely to substantially contribute to heat exchange.

[0047] In the example shown in FIG. 4B , the only area that contributes to heat exchange is the first side 131 of the cross section 12c closest to the heating element 100. In this example, although the spacing between adjacent cross sections 12c is long, the distance from the top surface 10u to the cross section 12c closest to the heating element 100 is short. Therefore, heat from the heating element 100 is not easily transferred to the left and right cross sections 12c adjacent to the cross section 12c closest to the heating element 100, and little heat flows between the adjacent cross sections 12c. Therefore, although heat exchange is preferentially performed from the first side 131 of the cross section 12c closest to the heating element 100, the first sides 131 of the left and right cross sections 12c do not substantially contribute to heat exchange. Furthermore, heat is not easily transferred to the second side 132, third side 133, and fourth side 134 of the cross section 12c closest to the heating element 100. Furthermore, the second side 132, the third side 133, and the fourth side 134 of the left and right cross sections 12c do not substantially contribute to heat exchange.

[0048] In the example shown in FIG. 4C , the regions contributing to heat exchange are three regions: the first side 131, the second side 132, and the third side 133 of the second cross section 12c from the left closest to the heating element 100, and the middle cross section 12c, as well as four regions including the fourth side 134. The regions contributing to heat exchange are two regions: the first side 131 and the second side 132 of the second cross section 12c from the right. In this example, the distance between adjacent cross sections 12c is relatively long, and the distance from the top surface 10u to the cross section 12c closest to the heating element 100 is also long. Therefore, heat from the heating element 100 is easily transferred not only to the cross section 12c closest to the heating element 100, but also to the cross sections 12c close to the cross section 12c. Furthermore, a relatively large amount of heat flows between the cross section 12c closest to the heating element 100 and the cross section 12c adjacent to that cross section 12c. In particular, since a large amount of heat enters between the second cross section 12c from the left and the middle cross section 12c, the heat also flows around to the fourth side 134 of the second cross section 12c from the left and the middle cross section 12c. Therefore, in the second cross section 12c from the left and the middle cross section 12c, which are close to the heating element 100, heat is exchanged not only at the first side 131 but also at the second side 132 and the third side 133, and further at the fourth side 134. Furthermore, in the second cross section 12c from the right, heat is exchanged not only at the first side 131 but also at the second side 132.

[0049] [Support structure] The above-described base 10 is supported by a support structure to form wafer holder 1. The support structure includes support body 20, temperature adjustment unit 30, leg members 40, and base plate 50, as shown in FIG.

[0050] (Support) The support 20 is a member for preventing warping of the base 10 due to heat generated during wafer inspection. The support 20 may be provided as needed and is not an essential member. If the support 20 is not provided, the base 10 is supported by the leg members 40, which will be described later. The support 20 provides the wafer holder 1 with reduced deformation resistance against forces applied from the upper surface 10u. In this embodiment, the support 20 is in close contact with the lower surface 10d of the base 10. By closely contacting the base 10 and the support 20, the rigidity of the entire wafer holder 1 can be increased. A known structure can be used to connect the support 20 to the base 10, and vacuum suction using a suction path (not shown) is preferably used. The overall shape of the support 20 is adapted to the shape of the base 10, and in this embodiment, it is a disk shape. The material of the support 20 is, for example, ceramic or a composite material of ceramic and metal. Examples of ceramics include alumina, mullite alumina, mullite, cordierite, steatite, silicon nitride, and silicon carbide. Because ceramics have high rigidity, if the support 20 is made of ceramics, warping of the base 10 can be easily suppressed.

[0051] (Temperature control unit) The temperature adjustment unit 30 is a unit for heating the wafer to a predetermined temperature. This temperature adjustment unit 30 can adjust the temperature of the wafer. In this embodiment, the temperature adjustment unit 30 is provided on the underside of the support 20. The temperature adjustment unit 30 has a disk-shaped heating element. A heater such as a resistance heating element is disposed on the heating element. The temperature adjustment unit 30 may further have a cooling function for cooling the wafer. For example, the temperature adjustment unit 30 may have an integrated structure of the heating element and the cooling element. A flow path for a refrigerant is formed within the cooling element. This refrigerant may be different from the refrigerant flowing through the flow path 12 of the base 10, but the same refrigerant may also be used.

[0052] (leg members) The leg members 40 are members that support the substrate 10 on the base plate 50. If the support 20 is present, the leg members 40 support the support 20 on the base plate 50. The leg members 40 are, for example, columnar or cylindrical in shape. The columnar or cylindrical leg members 40 pass through holes provided in the temperature adjustment unit 30 to support the support 20 or the substrate 10. The outer diameter of the columnar or cylindrical leg members 40 is sufficiently smaller than the outer diameter of the support 20 or the outer diameter of the substrate 10. Using columnar or cylindrical leg members 40 reduces the contact area between the leg members 40 and the support 20 or the contact area between the leg members 40 and the substrate 10. This reduces heat conduction to the base plate 50 via the leg members 40, maintaining the thermal uniformity of the substrate 10. Furthermore, using columnar or cylindrical leg members 40 can form a space between the temperature adjustment unit 30 and the base plate 50. This space contributes to thermal insulation between the base plate 50 and the substrate 10. The leg member 40 in this embodiment is a cylindrical body. It is preferable to provide a plurality of leg members 40 so as to support the base 10 or the support body 20 in a well-balanced manner. The material of the leg member 40 is, for example, any one of alumina, mullite alumina, mullite, cordierite, steatite, and silicon nitride.

[0053] (base plate) The base plate 50 is a member that serves as a pedestal that supports the substrate 10, the support body 20, the temperature adjustment unit 30, and the leg members 40. The material of this base plate 50 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.

[0054] "simulation" In order to verify the cooling performance of the base 10, a simulation experiment was carried out by changing the length L1, distance L2, distance L3, length L4, and distance L5 shown in FIG.

[0055] [Samples No. 1 to No. 6, Samples No. 101 to No. 104] In the cross section of the base 10 of each sample, the length L1 (mm), distance L2 (mm), distance L3 (mm), length L4 (mm), and distance L5 (mm) were as shown in Table 1. Distance L5 is the shortest distance between the fourth side 134 and the lower surface 10d of the base 10. Table 1 also shows the area S (mm 2 ), thickness T (mm), L2 / L1, and L1 / L3 are also shown. Area S is the product of length L1 and length L4. Thickness T is the thickness of substrate 10 and is the sum of distance L3, length L4, and distance L5.

[0056] Cooling performance evaluation The cooling performance of the base 10 was evaluated as follows. A heating element 100 was placed on the upper surface 10u of the base 10. The heating element 100 was a rectangular plate-shaped model with thermal conductivity equivalent to that of a silicon wafer. The heat density of the heating element 100 was 30 W / cm. 2 The side and top surfaces of the heating element 100 are insulated. While circulating a coolant through the flow path 12, power was supplied to the heating element 100 with a downward load applied to the top surface of the heating element 100. The applied load was 200 N. The power was supplied for one hour. The average temperature ΔT (°C) of the bottom surface 10d of the heating element 100 was calculated from 30 minutes to one hour, which is the time until the temperature becomes sufficiently constant. The results are shown in Table 1.

[0057] [Table 1]

[0058] As shown in Table 1, the average temperatures ΔT of the substrates 10 of Samples No. 1 to No. 6 were lower than the average temperatures ΔT of the substrates of Samples No. 101 to No. 104. This result shows that the substrates 10 of Samples No. 1 to No. 6 can cool the heating element 100 more efficiently than the substrates of Samples No. 101 to No. 104.

[0059] The present invention is not limited to these examples, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0060] 1 Wafer holder 10 base, 10u top, 10d bottom, 10c cross section 12 flow path, 12i inlet, 12e outlet 12c cross section, 121 first cross section, 122 second cross section 131 first side, 132 second side, 133 Third side, 134 Fourth side 20 support, 30 temperature adjustment unit 40 leg parts, 50 base plate 100 Heating element Area A L1 length, L2 distance, L3 distance, L4 length, L5 distance

Claims

1. a base that is a metal disk; a support and a temperature adjustment unit provided on the lower surface side of the base, the base has an upper surface on which a wafer is placed and a coolant flow path provided inside the base, a cross section of the substrate taken along a direction perpendicular to the upper surface has cross sections of a plurality of the flow channels; Each of the cross sections of the flow path is a cross section perpendicular to the flow direction of the refrigerant, The shape of each cross section of the flow path is rectangular; each of the cross sections of the flow path has a first side parallel to the top surface and closest to the top surface; a length L1 of the first side and a distance L2 between a first cross section and a second cross section adjacent to each other among the cross sections of the plurality of flow paths satisfy a relationship of 0.3≦(L2 / L1)≦2.5, a distance L3 between the first side and the upper surface and the length L1 satisfy the relationship (L1 / L3)≦1; Wafer holder.

2. 2. The wafer holder according to claim 1, wherein the length L1 and the distance L2 satisfy the relationship (L2 / L1)≦1.

3. Each of the cross sections of the flow path has a second side perpendicular to the first side, 3. The wafer holder according to claim 1, wherein the length L1 and the length L4 of the second side satisfy the relationship L1≦L4.

4. Each of the cross sections of the flow path has a second side perpendicular to the first side, 3. The wafer holder according to claim 1, wherein the length L1 and the length L4 of the second side satisfy the relationship L1>L4.

5. the substrate is made of copper or a copper alloy; The diameter of the upper surface is 100 mm or more and 400 mm or less, The area of ​​each of the cross sections of the flow path is 5 mm ２ That's all, 5. The wafer holder according to claim 1, wherein the thickness of the base is 15 mm or more and 30 mm or less.

6. 6. The wafer holder according to claim 1, wherein the length L1 is equal to or greater than 1 mm and equal to or less than 15 mm.

7. The support is a ceramic disk, 7. The wafer holder according to claim 1, wherein the base and the support are vacuum-attached.

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