Wafer holder and method for manufacturing a wafer holder

Abstract

The present invention provides a wafer holder in which a resin layer is firmly bonded to a ceramic substrate even after being subjected to heat cycling. [Solution] A wafer holder comprising a plate-shaped substrate, a first resin layer laminated on the first surface of the substrate, and an intermediate layer provided between the substrate and the first resin layer, wherein the substrate is formed of ceramics or a composite containing ceramics, the first resin layer is formed of polyimide resin, and the difference between the thermal expansion coefficient of the first resin layer and the thermal expansion coefficient of the substrate is 3 ppm / K or less.

Description

[Technical Field]

[0001] This disclosure relates to a wafer holder and a method for manufacturing a wafer holder. [Background technology]

[0002] Patent Document 1 discloses a substrate heat treatment apparatus for performing heat treatment on a substrate. This substrate heat treatment apparatus includes a resin support seal member positioned on the upper surface of a heat treatment plate. The substrate is placed on the support seal member. Hereinafter, the substrate will be referred to as a wafer, the heat treatment plate as a base, and the support seal member as a resin layer. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2007-158168 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] It is desirable that the substrate and the resin layer be firmly bonded. The substrate is preferably made of a highly rigid ceramic-based material. Depending on the materials of the substrate and the resin layer, bonding between the substrate and the resin layer may be difficult. Alternatively, the resin layer may delaminate from the substrate due to heat cycling.

[0005] One objective of this disclosure is to provide a wafer holder in which a resin layer is firmly bonded to a ceramic substrate even after heat cycling. Another objective of this disclosure is to provide a method for manufacturing the above wafer holder that can be easily produced. [Means for solving the problem]

[0006] The wafer holder of this disclosure comprises a plate-shaped substrate, a first resin layer laminated on the first surface of the substrate, and an intermediate layer provided between the substrate and the first resin layer. The substrate is formed of ceramics or a composite containing ceramics. The first resin layer is formed of polyimide resin. The difference between the thermal expansion coefficient of the first resin layer and the thermal expansion coefficient of the substrate is 3 ppm / K or less. [Effects of the Invention]

[0007] In the wafer holder of this disclosure, the resin layer is firmly bonded to the ceramic substrate even when subjected to heat cycling. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic cross-sectional view showing the wafer holder of Embodiment 1. [Figure 2] Figure 2 is a schematic cross-sectional view showing an enlarged portion of the wafer holder of Embodiment 2. [Figure 3] Figure 3 is a schematic cross-sectional view showing the wafer holder of Embodiment 3. [Figure 4] Figure 4 is a schematic cross-sectional view showing the wafer holder of Embodiment 4. [Figure 5] Figure 5 is a schematic plan view showing the wafer holder of Embodiment 4. [Figure 6] Figure 6 is a schematic cross-sectional view showing the wafer holder of Embodiment 5. [Figure 7] Figure 7 is a schematic cross-sectional view showing the wafer holder of Embodiment 6. [Figure 8] Figure 8 is a schematic diagram illustrating the manufacturing method of the wafer holder according to Embodiment 6. [Figure 9] Figure 9 is a schematic cross-sectional view showing the wafer holder of Embodiment 7. [Figure 10] Figure 10 is a schematic bottom view showing the wafer holder of Embodiment 7. [Figure 11] Figure 11 is a schematic cross-sectional view showing the wafer holder of Embodiment 8.

Embodiments for Carrying Out 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 holding stage according to one aspect of the present disclosure includes a plate-shaped substrate, a first resin layer laminated on a first surface of the substrate, and an intermediate layer provided between the substrate and the first resin layer. The substrate is formed of ceramics or a composite containing ceramics. The first resin layer is formed of a polyimide resin. The difference between the thermal expansion coefficient of the first resin layer and the thermal expansion coefficient of the substrate is 3 ppm / K or less.

[0011] A substrate formed of ceramics or a composite containing ceramics has higher rigidity at the same thickness compared to a case where it is formed only of metal. In the case of a wafer holding stage provided with a first resin layer, for example, if a wafer is placed on the first resin layer, the wafer does not come into contact with the substrate, so damage to the wafer by the substrate is unlikely to occur.

[0012] In the wafer holding stage of (1) above, since the difference between the thermal expansion coefficient of the first resin layer and the thermal expansion coefficient of the substrate is 3 ppm / K or less, even in a state where an intermediate layer is provided between the substrate and the first resin layer, the first resin layer is firmly joined to the substrate.

[0013] (2) In the wafer holding stage of (1) above, the difference between the combined thermal expansion coefficient of the first resin layer and the intermediate layer and the thermal expansion coefficient of the substrate may be 16 ppm / K or less. The combined thermal expansion coefficient is obtained by (Ka × Ta + Kb × Tb) / (Ta + Tb). Ka is the thermal expansion coefficient of the first resin layer. Kb is the thermal expansion coefficient of the intermediate layer. Ta is the thickness of the first resin layer. Tb is the thickness of the intermediate layer. The units of Ka and Kb are ppm / K. The units of Ta and Tb are μm.

[0014] If the difference between the composite thermal expansion coefficient of the first resin layer and the intermediate layer and the thermal expansion coefficient of the substrate is 16 ppm / K or less, the first resin layer is more firmly bonded to the substrate. If the difference between the composite thermal expansion coefficient of the first resin layer and the intermediate layer and the thermal expansion coefficient of the substrate is 16 ppm / K or less, as shown in the test examples described later, the first resin layer is difficult to peel off from the substrate even when subjected to a heat cycle.

[0015] (3) In the wafer holding stage of the above (1) or the above (2), the surface roughness of the first surface may be 1 μm or more and 10 μm or less in terms of arithmetic mean roughness Ra.

[0016] When the first surface of the substrate is a rough surface, the surface roughness is defined by the irregularities constituting the rough surface. If the surface roughness of the first surface of the substrate is 1 μm or more in terms of Ra, the intermediate layer fits into the irregularities, and the first resin layer on the intermediate layer is more firmly bonded to the substrate. If the surface roughness of the first surface of the substrate is 10 μm or less in terms of Ra, it is difficult to form a gap between the first surface and the intermediate layer, that is, the intermediate layer easily fits into the irregularities.

[0017] (4) In the wafer holding stage of any one of the above (1) to the above (3), the intermediate layer may include a first adhesive layer formed of a thermoplastic polyimide resin.

[0018] When the intermediate layer includes the first adhesive layer, the first resin layer is more firmly bonded to the substrate.

[0019] (5) In the wafer holding stage of any one of the above (1) to the above (3), the intermediate layer may include a first adhesive layer, a second resin layer, and a second adhesive layer. The first adhesive layer is in contact with the first surface. The second resin layer is provided between the first adhesive layer and the second adhesive layer. The first adhesive layer and the second adhesive layer are formed of a thermoplastic polyimide resin.

[0020] If the intermediate layer includes a first adhesive layer and a second adhesive layer, the first adhesive layer is bonded to the substrate and the second adhesive layer is bonded to the first resin layer. By bonding the substrate and the first resin layer to the intermediate layer, the first resin layer is more firmly bonded to the substrate.

[0021] (6) In the wafer holder described in (5) above, the intermediate layer may further include a third adhesive layer, a third resin layer, and a fourth adhesive layer. The third adhesive layer is in contact with the second adhesive layer. The third resin layer is provided between the third adhesive layer and the fourth adhesive layer. The third adhesive layer and the fourth adhesive layer are made of thermoplastic polyimide resin.

[0022] Because the three-layer structure, in which a resin layer is sandwiched between two adhesive layers, is further laminated, it is easier to position, for example, the metal layer described later, at a specific location between the two three-layer structures.

[0023] (7) Any wafer holder described in (1) to (6) above may include one or more metal layers disposed between the substrate and the intermediate layer or inside the intermediate layer. The metal layers are arranged in a plane parallel to the first surface.

[0024] For example, if the first resin layer has the function of supporting the wafer, and the metal layer is placed between the substrate and the intermediate layer or inside the intermediate layer, the first resin layer will be less likely to deform even when subjected to the load of the wafer and the load acting on the wafer.

[0025] (8) In the wafer holder described in (7) above, the metal layers may be multiple, and the surface of the first resin layer may have multiple protrusions in the portion corresponding to the location where the multiple metal layers are arranged.

[0026] Multiple protrusions on the surface of the first resin layer serve to support the lower surface of the wafer. A metal layer is positioned below each protrusion. Therefore, each protrusion is resistant to being crushed even when subjected to the weight of the wafer and the loads acting on the wafer.

[0027] (9) In the wafer holder described in (7) above, the metal layer may be a heating element.

[0028] When the metal layer is the heating element, the first resin layer is firmly bonded to the substrate, eliminating the need for a plate-like member to support the layer containing the heating element from below.

[0029] (10) A method for manufacturing a wafer holder according to one aspect of the present disclosure comprises the steps of preparing a first resin film, a second resin film, a third resin film, a metal film, and a substrate, and sequentially laminating the second resin film, the metal film, the third resin film, and the first resin film on the substrate. The substrate is formed of ceramics or a composite containing ceramics. The first resin film is formed of polyimide resin. Each of the second resin film and the third resin film comprises a first layer and two second layers laminated on the first layer so as to sandwich the first layer. At least the two second layers are formed of thermoplastic polyimide resin. The difference between the thermal expansion coefficient of the first resin film and the thermal expansion coefficient of the substrate is 3 ppm / K or less.

[0030] The wafer holder described in (10) above can be easily manufactured using this method.

[0031] [Details of the embodiments of this disclosure] Specific examples of the wafer holder and the method for manufacturing the wafer holder described herein will be explained with reference to the drawings. Identical reference numerals in the drawings indicate the same or corresponding parts. In each drawing, some parts of the configuration may be exaggerated or simplified for ease of explanation. The dimensional ratios of parts in the drawings may also differ from those of the actual components. The present invention is not limited to these examples, but is shown in the claims, and all modifications within the meaning and scope of equivalence to the claims are intended.

[0032] <Embodiment 1> As shown in Figure 1, the wafer holder 1 of Embodiment 1 comprises a substrate 2, a first resin layer 3, and an intermediate layer 4. The substrate 2 is formed of ceramics or a composite containing ceramics. The first resin layer 3 is formed of polyimide resin. The intermediate layer 4 is provided between the substrate 2 and the first resin layer 3. One of the features of the wafer holder 1 of Embodiment is that the difference between the thermal expansion coefficient of the first resin layer 3 and the thermal expansion coefficient of the substrate 2 is 3 ppm / K or less. The wafer holder 1 is used, for example, in semiconductor manufacturing equipment.

[0033] Embodiment 1 describes an example in which the substrate 2 is a heat transfer member and the first resin layer 3 has the function of supporting a wafer (not shown) from below.

[0034] ≪Base≫ The base body 2 is a plate-shaped member that constitutes the main part of the wafer holder 1. The base body 2 has a first surface 21 and a second surface 22. An intermediate layer 4 and a first resin layer 3 are sequentially laminated on the first surface 21. A heater member (not shown) is placed on the second surface 22 in this example. The base body 2 has the function of transferring heat from the heater member to the first resin layer 3. Hereinafter, the direction from the second surface 22 toward the first surface 21 may be referred to as the first direction D1.

[0035] The substrate 2 is formed of ceramics or a composite containing ceramics. The substrate 2 formed of ceramics or a composite containing ceramics has excellent thermal conductivity and heat resistance. The substrate 2 formed of ceramics or a composite containing ceramics has higher rigidity for the same thickness compared to the case where it is formed of metal only. Examples of ceramics are silicon carbide (SiC), aluminum nitride, aluminum oxide, or silicon nitride. Examples of composites containing ceramics are a composite of silicon (Si) and silicon carbide, a composite of aluminum (Al) and silicon carbide, or a composite of aluminum, silicon, and silicon carbide.

[0036] ≪First resin layer≫ The first resin layer 3 is laminated on the first surface 21 of the substrate 2. In this example, a wafer (not shown) is placed on the first resin layer 3. The first resin layer 3 is made of polyimide resin. The first resin layer 3, made of polyimide resin, is less likely to scratch the wafer placed on it.

[0037] The difference between the thermal expansion coefficient of the first resin layer 3 and the thermal expansion coefficient of the substrate 2 is 3 ppm / K or less. When the above difference is 3 ppm / K or less, the first resin layer 3 is firmly bonded to the substrate 2 even when an intermediate layer 4 is provided between the substrate 2 and the first resin layer 3. The difference between the thermal expansion coefficient of the first resin layer 3 and the thermal expansion coefficient of the substrate 2 may be 2 ppm / K or less, 1.5 ppm / K or less, 1 ppm / K or less, or 0.5 ppm / K or less.

[0038] As the constituent material of the first resin layer 3, a polyimide resin having a coefficient of thermal expansion that satisfies a difference of 3 ppm / K or less from the coefficient of thermal expansion of the substrate 2 is selected.

[0039] The thickness Ta of the first resin layer 3 is, for example, 18 μm or more and 50 μm or less. The thickness Ta is the average distance obtained by measuring the distance between the interface between the first resin layer 3 and the intermediate layer 4 and the surface of the first resin layer 3 at three or more different locations. In this example, the surface of the first resin layer 3 is the surface on which the wafer is placed. If the thickness Ta is 18 μm or more, it is difficult to deform even when subjected to the load of the wafer and the load acting on the wafer. If the thickness Ta is 18 μm or more, wrinkles are less likely to form even when subjected to heat cycles. If the thickness Ta is 50 μm or less, the thermal response when heating the wafer is good. The thickness Ta may also be 25 μm or more and 38 μm or less.

[0040] ≪Middle Class≫ The intermediate layer 4 has the function of bonding the first resin layer 3 to the substrate 2. The intermediate layer 4 includes, for example, a first adhesive layer 51 made of thermoplastic polyimide resin. When the intermediate layer 4 includes the first adhesive layer 51, the first resin layer 3 is bonded more firmly to the substrate 2. In this example, the intermediate layer 4 consists of the first adhesive layer 51. In other words, the intermediate layer 4 in this example is a single layer.

[0041] The difference between the combined thermal expansion coefficient of the first resin layer 3 and the intermediate layer 4 and the thermal expansion coefficient of the substrate 2 is, for example, 16 ppm / K or less. The combined thermal expansion coefficient is calculated as (Ka × Ta + Kb × Tb) / (Ta + Tb). Ka is the thermal expansion coefficient of the first resin layer 3. Kb is the thermal expansion coefficient of the intermediate layer 4. Ta is the thickness of the first resin layer 3. Tb is the thickness of the intermediate layer 4. The units of Ka and Kb are ppm / K. The units of Ta and Tb are μm. The thickness Tb is the average distance obtained by measuring the distance between the interface between the first resin layer 3 and the intermediate layer 4 and the interface between the substrate 2 and the intermediate layer 4 at three or more different locations.

[0042] If the difference between the combined thermal expansion coefficient of the first resin layer 3 and the intermediate layer 4 and the thermal expansion coefficient of the substrate 2 is 16 ppm / K or less, the first resin layer 3 will be more firmly bonded to the substrate 2. If the difference between the combined thermal expansion coefficient of the first resin layer 3 and the intermediate layer 4 and the thermal expansion coefficient of the substrate 2 is 16 ppm / K or less, the first resin layer 3 will be less likely to peel off from the substrate 2 even when subjected to heat cycling, as will be shown in the test examples described later. The difference between the combined thermal expansion coefficient of the first resin layer 3 and the intermediate layer 4 and the thermal expansion coefficient of the substrate 2 may be 15 ppm / K or less, or 13 ppm / K or less.

[0043] As the intermediate layer 4, a material is selected that has a thermal expansion coefficient such that the difference between the combined thermal expansion coefficient of the first resin layer 3 and the intermediate layer 4 and the thermal expansion coefficient of the substrate 2 is 16 ppm / K or less. In this example, as the constituent material of the intermediate layer 4, a thermoplastic polyimide resin is selected that has a thermal expansion coefficient such that the difference between the combined thermal expansion coefficient of the first resin layer 3 and the intermediate layer 4 and the thermal expansion coefficient of the substrate 2 is 16 ppm / K or less.

[0044] The thickness Tb of the intermediate layer 4 is, for example, 25 μm or more and 100 μm or less. If the thickness Tb is 25 μm or more, the first resin layer 3 is more easily bonded to the substrate 2. If the thickness Tb is 100 μm or less, the thermal response when heating the wafer is good. The thickness Tb may also be 50 μm or more and 75 μm or less.

[0045] The intermediate layer 4 may be formed of an adhesive capable of bonding the first resin layer 3 to the substrate 2, rather than the first adhesive layer 51 being made of a thermoplastic polyimide resin. The intermediate layer 4 may also be formed of an adhesive containing a polyimide resin, or an adhesive sheet containing a thermosetting polyimide resin.

[0046] <Embodiment 2> In the wafer holder 1 of Embodiment 2, as shown in Figure 2, irregularities 210 are formed on the first surface 21 of the substrate 2. At least a portion of the intermediate layer 4 is fitted into the irregularities 210. The intermediate layer 4 in this example consists of a first adhesive layer 51. The wafer holder 1 of Embodiment 2 differs from Embodiment 1 in that irregularities 210 are formed on the first surface 21.

[0047] As an indicator representing the irregularities 210, the surface roughness of the first surface 21 is, for example, 1 μm or more and 10 μm or less in arithmetic mean roughness Ra. If the surface roughness of the first surface 21 is 1 μm or more in Ra, the intermediate layer 4 fits into the irregularities 210, and the first resin layer 3 on the intermediate layer 4 is bonded more firmly to the substrate 2. If the surface roughness of the first surface 21 is 10 μm or less in Ra, a gap is less likely to form between the first surface 21 and the intermediate layer 4, meaning that the intermediate layer 4 fits into the irregularities 210 more easily. The surface roughness of the first surface 21 may also be 2 μm or more and 8 μm or less in arithmetic mean roughness Ra, or 3 μm or more and 6 μm or less. The arithmetic mean roughness Ra is measured in accordance with JIS B 0601:2013.

[0048] The irregularities 210 may be random irregularities corresponding to the surface roughness of the first surface 21, or they may be regularly formed irregularities.

[0049] The entire intermediate layer 4 may be fitted into the grooves 210, or a part of the intermediate layer 4 may be fitted into the grooves 210. The tips of some of the protrusions of the grooves 210 may extend into the first resin layer 3.

[0050] If the intermediate layer 4 includes a first adhesive layer 51 made of thermoplastic polyimide resin, then by heat pressing the first adhesive layer 51 so that it is in contact with the first surface 21, the first adhesive layer 51 can easily fit into the irregularities 210, and the first resin layer 3 can be more firmly bonded to the substrate 2.

[0051] <Embodiment 3> In the wafer holder 1 of Embodiment 3, as shown in Figure 3, the intermediate layer 4 includes a second resin layer 50, a first adhesive layer 51, and a second adhesive layer 52. The intermediate layer 4 in this example has a three-layer structure in which the second resin layer 50 is positioned between the first adhesive layer 51 and the second adhesive layer 52. The wafer holder 1 of Embodiment 3 differs from Embodiment 1 in the configuration of the intermediate layer 4.

[0052] The second resin layer 50 constitutes the main part of the intermediate layer 4. The first adhesive layer 51 is in contact with the first surface 21 of the substrate 2. The first adhesive layer 51 joins the substrate 2 and the second resin layer 50. In this example, the second adhesive layer 52 is in contact with the first resin layer 3. The second adhesive layer 52 joins the first resin layer 3 and the second resin layer 50.

[0053] The second resin layer 50 is formed of, for example, polyimide resin. When the second resin layer 50, which constitutes the main part of the intermediate layer 4, is formed of polyimide resin, the intermediate layer 4 can be made thinner while still having sufficient heat resistance. The second resin layer 50 may be formed of thermoplastic polyimide resin or thermosetting polyimide resin.

[0054] The first adhesive layer 51 and the second adhesive layer 52 are formed of, for example, a thermoplastic polyimide resin. When the first adhesive layer 51 and the second adhesive layer 52 are formed of a thermoplastic polyimide resin, the first adhesive layer 51 is easily bonded to the substrate 2 and the second adhesive layer 52 is easily bonded to the first resin layer 3 by heat pressing so that the first adhesive layer 51 is in contact with the first surface 21 and the second adhesive layer 52 is in contact with the first resin layer 3. As the substrate 2 and the first resin layer 3 are bonded to the intermediate layer 4, the first resin layer 3 is more firmly bonded to the substrate 2.

[0055] The second resin layer 50, the first adhesive layer 51, and the second adhesive layer 52 may be integrally molded. For example, when the second resin layer 50, the first adhesive layer 51, and the second adhesive layer 52 are integrally molded from polyimide resin, as described above, the first adhesive layer 51 and the second adhesive layer 52 are formed from thermoplastic polyimide resin. The second resin layer 50, the first adhesive layer 51, and the second adhesive layer 52 may be separate from each other. For example, the first adhesive layer 51 and the second adhesive layer 52, which are made of an adhesive containing polyimide resin, may be laminated on the second resin layer 50. A polyimide film having thermoplastic polyimide layers on both sides of a heat-resistant polyimide layer can also be made using commercially available films.

[0056] If the intermediate layer 4 has a multilayer structure consisting of multiple layers, the thickness Tb of the intermediate layer 4 is the sum of the thicknesses of each layer. If the intermediate layer 4 has a multilayer structure consisting of multiple layers, the thermal expansion coefficient of the intermediate layer 4 is the combined thermal expansion coefficient of all layers. The combined thermal expansion coefficient of all layers is the value obtained by dividing the sum of the products of the thermal expansion coefficient and thickness of each layer by the sum of the total thicknesses of all layers.

[0057] <Embodiment 4> As shown in Figure 4, the wafer holder 1 of Embodiment 4 comprises a plurality of metal layers 7 disposed between the substrate 2 and the intermediate layer 4. The plurality of metal layers 7 are arranged in a single plane parallel to the first surface 21 of the substrate 2. The plurality of metal layers 7 are dispersed on the first surface 21. The intermediate layer 4 and the first resin layer 3 are sequentially laminated on the first surface 21 on which the plurality of metal layers 7 are dispersed. In this example, the surface of the first resin layer 3 is provided with a plurality of protrusions 30 in the portions corresponding to the locations where the plurality of metal layers 7 are arranged. The wafer holder 1 of Embodiment 4 differs from Embodiment 1 in that it comprises a plurality of metal layers 7, and a plurality of protrusions 30 are provided on the surface of the first resin layer 3 corresponding to the plurality of metal layers 7.

[0058] ≪Metal layer≫ The metal layer 7 contributes to maintaining the shape of the protrusions 30. The number of metal layers 7 is the same as the number of protrusions 30. When the first resin layer 3 and the metal layer 7 are viewed in the first direction D1, the locations of the metal layers 7 and the locations of the protrusions 30 are the same. The locations of the metal layers 7 will be described later.

[0059] The thickness 7T of the multiple metal layers 7 may all be the same. The multiple metal layers 7 contribute to the formation of the multiple protrusions 30. If the thickness 7T of the multiple metal layers 7 is all the same, the height 30H of the multiple protrusions 30 is likely to be the same. The statement that the thickness 7T of the multiple metal layers 7 is all the same includes a tolerance that is practically acceptable. The tolerance is, for example, within ±20% or ±10% of the design dimension.

[0060] The thickness 7T of each of the multiple metal layers 7 is, for example, between 30 μm and 200 μm. The thickness 7T is the average distance obtained by measuring the distance between the upper and lower surfaces of each metal layer 7 at three or more different locations. The protrusion 30 has the function of supporting the lower surface of the wafer placed on the first resin layer 3. If the thickness 7T is 30 μm or more, the wafer is easily supported by the protrusion 30. If the thickness 7T is 200 μm or less, the height of the protrusion 30 will not become too high. The thickness 7T may also be between 40 μm and 150 μm, or between 50 μm and 100 μm.

[0061] The metal layer 7 includes, for example, one or more materials selected from the group consisting of stainless steel, Kovar, nickel, nickel alloys, aluminum, and aluminum alloys. As described above, the metal layer 7 contributes to maintaining the shape of the projection 30. Because the metal layer 7, made of the metals listed above, is positioned below the projection 30, the projection 30 is less likely to be crushed even when subjected to the load of the wafer or a load acting on the wafer.

[0062] ≪Protrusion≫ Multiple protrusions 30 are formed by the metal layer 7 causing a raised portion of the intermediate layer 4 and the first resin layer 3. Each protrusion 30 is formed by a portion of the first resin layer 3 projecting in the first direction D1. The metal layer 7 is positioned below each protrusion 30. In other words, when viewing the first resin layer 3 and the metal layer 7 in the first direction D1, the locations of the protrusions 30 correspond to the locations of the metal layer 7.

[0063] The multiple protrusions 30 have the function of supporting the lower surface of the wafer. As shown in Figure 5, the multiple protrusions 30 consist of multiple first protrusions 31 and one second protrusion 32. Figure 5 is a plan view of the first resin layer 3 along the first direction D1.

[0064] Multiple first protrusions 31 are arranged in a point-like manner in a plan view of the first resin layer 3. Multiple first protrusions 31 are dispersed on the surface of the first resin layer 3 without aggregation. Adjacent first protrusions 31 are spaced apart by a certain amount of distance. For example, the distance between adjacent first protrusions 31 is 10 mm to 100 mm, or 20 mm to 50 mm. If the multiple first protrusions 31 are uniformly dispersed, the wafer can be stably supported. Multiple first protrusions 31 are formed by multiple metal layers 7 (Figure 4) arranged in a point-like manner.

[0065] Each first projection 31 has, for example, a flat tip surface. A flat tip surface makes it easier to support the wafer. Multiple first projections 31 are arranged, for example, so that all of their tip surfaces are located in a plane parallel to the first surface 21. The corners of each first projection 31 that connect from the tip surface to the side surface are, for example, curved. Curved corners are less likely to damage the wafer. The tip surface may also be curved.

[0066] The shape of the tip surface of each first projection 31 may be circular or polygonal in plan view. Circular shapes include perfect circles and ellipses. Polygonal shapes include shapes with rounded corners. In Figure 5, the tip surface of each first projection 31 is shown as circular.

[0067] The area of ​​the tip surface of each first projection 31 is, for example, 0.02 mm². 2 4.00 mm 2 The following applies: The area of ​​the tip surface of each first projection 31 is 0.02 mm². 2 The wafer is easier to support if the area of ​​the tip surface of each first projection 31 is 4.00 mm². 2In the following case, when a heater member is disposed on the second surface 22 of the substrate 2 to heat the wafer, the heat transfer area with respect to the wafer does not become too large, and local temperature variations are unlikely to occur. The area of the tip surface of each first protrusion 31 is 4.00 mm 2 In the following case, a gap is relatively easily formed between the first resin layer 3 and the wafer. As will be described later, by discharging the gas in this gap, the wafer can be adsorbed to the wafer holding stage 1. The area of the tip surface of each first protrusion 31 is 0.07 mm 2 or more and 1.75 mm 2 or less, or 0.20 mm 2 or more and 0.80 mm 2 or less may also be acceptable.

[0068] The second protrusions 32 are linearly arranged so as to surround all of the plurality of first protrusions 31. The shape of the second protrusions 32 in plan view is, for example, an annular shape concentric with the wafer holding stage 1. The second protrusions 32 can enhance the airtightness between the wafer placed on the protrusions 30 and the first resin layer 3. In a state where the wafer is placed on the protrusions 30, the inner space surrounded by the second protrusions 32 can be made sufficiently lower in pressure than the outer space. When the gas between the wafer placed on the protrusions 30 and the first resin layer 3 is discharged, the wafer can be adsorbed to the wafer holding stage 1. The second protrusions 32 have a function of enhancing the airtightness between the wafer and the wafer holding stage 1 in addition to the function of supporting the wafer.

[0069] The tip surface of the second protrusions 32 is, for example, flat. When the tip surface of the second protrusions 32 is flat, it is easy to support the wafer and it is easy to seal the space between the wafer and the wafer holding stage 1.

[0070] The width of the second projection 32 is, for example, 0.2 mm or more and 1.0 mm or less. If the width is 0.2 mm or more, it is easier to support the vicinity of the wafer edge with the second projection 32 and it is easier to improve the airtightness between the wafer and the wafer holder 1. If the width is 1.0 mm or less, the number of first projections 31 can be increased relatively. The width is the maximum distance in the direction perpendicular to the length of the second projection 32. The width of the second projection 32 may be 0.3 mm or more and 0.6 mm or less, or 0.4 mm or more and 0.5 mm or less.

[0071] In this example, the height 30H of all the protrusions 30, including the multiple first protrusions 31 and second protrusions 32, is the same. If the height 30H of all the protrusions 30 is the same, the wafer can be stably supported by the protrusions 30. The height 30H of all the protrusions 30 being the same includes a tolerance that is practically acceptable. The tolerance is, for example, within ±20% or ±10% of the design dimension.

[0072] In this example, the height 30H of each projection 30 and the thickness 7T of each metal layer 7 are the same. The height 30H of each projection 30 is, for example, 30 μm or more and 200 μm or less. If the height 30H is 30 μm or more, it is easier to support the wafer. If the height 30H is 200 μm or less, the gap between the wafer and the wafer holder 1 does not become too large, making it easier to expel the gas from this gap and making it easier to adsorb the wafer to the wafer holder 1. The height 30H may also be 40 μm or more and 150 μm or less, or 50 μm or more and 100 μm or less.

[0073] Even if a metal layer 7 is placed between the substrate 2 and the intermediate layer 4, the metal layer 7 does not affect the combined thermal expansion coefficient of the first resin layer 3 and the intermediate layer 4. In other words, when determining the combined thermal expansion coefficient of the first resin layer 3 and the intermediate layer 4, the thickness and thermal expansion coefficient of the metal layer 7 can be ignored.

[0074] <Embodiment 5> As shown in Figure 6, the wafer holder 1 of Embodiment 5 includes a plurality of metal layers 7 arranged inside the intermediate layer 4. The intermediate layer 4 in this example includes a first adhesive layer 51 and a second adhesive layer 52. The intermediate layer 4 in this example has a two-layer structure consisting of the first adhesive layer 51 and the second adhesive layer 52. The plurality of metal layers 7 are dispersed between the first adhesive layer 51 and the second adhesive layer 52. In this example, the surface of the first resin layer 3 has a plurality of protrusions 30 in the portions corresponding to the locations where the plurality of metal layers 7 are arranged. The wafer holder 1 of Embodiment 5 differs from Embodiment 4 in that the intermediate layer 4 includes a first adhesive layer 51 and a second adhesive layer 52, and the plurality of metal layers 7 are arranged between the first adhesive layer 51 and the second adhesive layer 52.

[0075] The first adhesive layer 51 and the second adhesive layer 52 are joined with multiple metal layers 7 sandwiched between them. If multiple metal layers 7 can be placed between the first adhesive layer 51 and the second adhesive layer 52, it is easier to place multiple metal layers 7 at specific locations within the intermediate layer 4.

[0076] The first adhesive layer 51 is in contact with the first surface 21 of the substrate 2. The second adhesive layer 52 is in contact with the first resin layer 3. The first adhesive layer 51 and the second adhesive layer 52 are formed of, for example, a thermoplastic polyimide resin. The first adhesive layer 51 and the second adhesive layer 52 are, for example, heat-fused together.

[0077] The first adhesive layer 51 and the second adhesive layer 52 may have the same thickness and material, or at least one of them may be different in thickness and material.

[0078] Multiple protrusions 30 are formed by the metal layer 7 causing a raised portion of the second adhesive layer 52 and the first resin layer 3.

[0079] <Embodiment 6> In the wafer holder 1 of Embodiment 6, as shown in Figure 7, the intermediate layer 4 includes a first intermediate layer 5 and a second intermediate layer 6, and a plurality of metal layers 7 are dispersed between the first intermediate layer 5 and the second intermediate layer 6. Each of the first intermediate layer 5 and the second intermediate layer 6 has a three-layer structure. In this example, the surface of the first resin layer 3 has a plurality of protrusions 30 in the parts corresponding to the locations where the plurality of metal layers 7 are arranged. The wafer holder 1 of Embodiment 6 differs from Embodiment 5 in the configuration of the intermediate layer 4.

[0080] The first intermediate layer 5 includes a second resin layer 50, a first adhesive layer 51, and a second adhesive layer 52. In this example, the first intermediate layer 5 has a three-layer structure in which the second resin layer 50 is positioned between the first adhesive layer 51 and the second adhesive layer 52. The second resin layer 50, the first adhesive layer 51, and the second adhesive layer 52 in the first intermediate layer 5 have the same configuration as the second resin layer 50, the first adhesive layer 51, and the second adhesive layer 52 described in Embodiment 3. The first adhesive layer 51 is in contact with the first surface 21 of the substrate 2. In this example, the second adhesive layer 52 is in contact with the second intermediate layer 6.

[0081] The second intermediate layer 6 includes a third resin layer 60, a third adhesive layer 61, and a fourth adhesive layer 62. In this example, the second intermediate layer 6 has a three-layer structure in which the third resin layer 60 is positioned between the third adhesive layer 61 and the fourth adhesive layer 62. The second intermediate layer 6 has the same configuration as the first intermediate layer 5. The third resin layer 60 has the same configuration as the second resin layer 50. The third adhesive layer 61 has the same configuration as the first adhesive layer 51. The fourth adhesive layer 62 has the same configuration as the second adhesive layer 52. The third adhesive layer 61 is in contact with the second adhesive layer 52. The fourth adhesive layer 62 is in contact with the first resin layer 3. In this example, the intermediate layer 4 has a six-layer structure consisting of the first intermediate layer 5 and the second intermediate layer 6.

[0082] The first adhesive layer 51, the second adhesive layer 52, the third adhesive layer 61, and the fourth adhesive layer 62 are formed of, for example, a thermoplastic polyimide resin. When the first adhesive layer 51, the second adhesive layer 52, the third adhesive layer 61, and the fourth adhesive layer 62 are formed of a thermoplastic polyimide resin, the first intermediate layer 5, a plurality of metal layers 7, the second intermediate layer 6, and the first resin layer 3 can be laminated in order on the first surface 21 of the substrate 2 and then hot-pressed. By hot-pressing, the first intermediate layer 5 and the second intermediate layer 6 are joined with the plurality of metal layers 7 in between, the first adhesive layer 51 is joined to the substrate 2, and the fourth adhesive layer 62 is easily joined to the first resin layer 3.

[0083] Referring to Figure 8, the manufacturing method of the wafer holder 1 of Embodiment 6 will be described. The manufacturing method of the wafer holder 1 of Embodiment 6 comprises a preparation step of preparing a substrate 2 and a laminate for the substrate 2, and a lamination step of laminating the laminate on the substrate 2.

[0084] In the preparation process, as shown in the upper diagram of Figure 8, the first resin film 300, the second resin film 500, the third resin film 600, the metal film 700, and the substrate 2 are prepared. The substrate 2 is the substrate 2 of the wafer holder 1 described above. The first resin film 300 is the material of the first resin layer 3 described above. The first resin film 300 is made of polyimide resin. For the first resin film 300, a polyimide resin having a coefficient of thermal expansion that satisfies the difference with the coefficient of thermal expansion of the substrate 2 to be 3 ppm / K or less is selected. The second resin film 500 is the material of the first intermediate layer 5 described above. The second resin film 500 has a three-layer structure in which the first layer 510 is placed between two second layers 511 and 512. The first layer 510 is the material of the second resin layer 50. The second layer 511 is the material of the first adhesive layer 51. The second layer 512 is the material of the second adhesive layer 52. The third resin film 600 is the material of the second intermediate layer 6 described above. The third resin film 600 has a three-layer structure in which the first layer 610 is positioned between two second layers 611 and 612. The first layer 610 is the material of the third resin layer 60. The second layer 611 is the material of the third adhesive layer 61. The second layer 612 is the material of the fourth adhesive layer 62. At least the second layers 511, 512, 611, and 612 are formed of thermoplastic polyimide resin.

[0085] In the lamination process, a second resin film 500, a metal film 700, a third resin film 600, and a first resin film 300 are sequentially laminated on the substrate 2. First, as shown by the arrow in the upper part of Figure 8, the second resin film 500 and the metal film 700 are laminated. Next, as shown in the middle part of Figure 8, the metal film 700 on the second resin film 500 is etched into a predetermined shape to form multiple metal layers 7. The multiple metal layers 7 are parts of a single metal film 700. In Figure 8, for the sake of explanation, three metal layers 7 are shown. After forming the metal layers 7 of the predetermined shape, as shown in the lower part of Figure 8, the second resin film 500 and the third resin film 600 are stacked so as to sandwich the multiple metal layers 7, and then the first resin film 300 is stacked on top of the third resin film 600 to form a laminate. This laminate is then laminated onto the substrate 2 and hot-pressed. The hot pressing should be performed at a temperature and pressure such that the joint surfaces between the base 2 and the second resin film 500, the joint surface between the second resin film 500 and the third resin film 600, and the joint surface between the third resin film 600 and the first resin film 300 are heat-fused together.

[0086] During heat pressing, the side of the first resin film 300 opposite to the side overlapping with the third resin film 600 is brought into contact with the cushioning material 800. The side in contact with the cushioning material 800 is deformed by the heat pressing. Specifically, the overlapping portion of the first resin film 300 and the third resin film 600 that overlaps with the metal layer 7 is raised by the metal layer 7 due to the heat pressing. This raised portion is the projection 30 shown in Figure 7. During heat pressing, a release film (not shown) may be placed between the first resin film 300 and the cushioning material 800.

[0087] With this manufacturing method, multiple metal layers 7 are formed from a single metal film 700, so the thickness 7T of all the metal layers 7 can be made the same. During heat pressing, the surface in contact with the cushioning material 800 rises according to the thickness 7T of the metal layer 7, so that a projection 30 having the same height 30H as the thickness 7T of the metal layer 7 can be formed. Since the thickness 7T of all the metal layers 7 is the same, the height 30H of all the formed projections 30 can be made the same.

[0088] <Embodiment 7> As shown in Figures 9 and 10, the wafer holder 1 of Embodiment 7 comprises a series of metal layers 7 arranged inside the intermediate layer 4. The metal layers 7 are heating elements. The metal layers 7 are formed, for example, from a thin metallic film that generates heat when an electric current is passed through it. In this example, the substrate 2 is a heat transfer member, and the first resin layer 3 and the intermediate layer 4 are heater members. A wafer (not shown) is placed on the second surface 22 of the substrate 2. The intermediate layer 4 and the first resin layer 3 described in Embodiments 1 to 6 may be laminated on the second surface 22. In this case, the wafer is placed on the first resin layer 3 laminated on the second surface 22. The wafer holder 1 of Embodiment 7 differs from Embodiment 5 in that the function of the metal layers 7 is different.

[0089] Figure 10 is a bottom view of the wafer holder 1 as seen from the first resin layer 3, with the metal layer 7 indicated by a dashed line. A series of circuit patterns are formed by the metal layer 7, which is made of heating elements. The circuit patterns are appropriately selected according to the heating temperature and the desired temperature distribution. The metal layer 7, which is made of heating elements, is arranged in a single plane parallel to the first surface 21 of the substrate 2. Multiple metal layers 7, each made of heating elements, may be arranged at intervals in the first direction D1. In Figure 9, for the sake of explanation, a part of the metal layer 7 is simplified, and its dimensions and pattern differ from those of the metal layer 7 in Figure 10.

[0090] As shown in Figure 9, the intermediate layer 4 of this example comprises a first adhesive layer 51 and a second adhesive layer 52. The intermediate layer 4 of this example has a two-layer structure consisting of a first adhesive layer 51 and a second adhesive layer 52. The first adhesive layer 51 and the second adhesive layer 52 of this example have the same configuration as the first adhesive layer 51 and the second adhesive layer 52 described in Embodiment 5. The metal layer 7 is placed between the first adhesive layer 51 and the second adhesive layer 52. The first adhesive layer 51 and the second adhesive layer 52 are joined with the metal layer 7 in between. If the metal layer 7 can be placed between the first adhesive layer 51 and the second adhesive layer 52, it is easier to place the metal layer 7, which is a heating element, at a specific location inside the intermediate layer 4.

[0091] In this example as well, the difference between the thermal expansion coefficient of the first resin layer 3 and the thermal expansion coefficient of the substrate 2 is 3 ppm / K or less. Therefore, the first resin layer 3 is firmly bonded to the substrate 2.

[0092] <Embodiment 8> As shown in Figure 11, the wafer holder 1 of Embodiment 8 has an intermediate layer 4 which includes a first intermediate layer 5 and a second intermediate layer 6, with a series of metal layers 7 arranged between the first intermediate layer 5 and the second intermediate layer 6. Each of the first intermediate layer 5 and the second intermediate layer 6 has a three-layer structure. The first intermediate layer 5 and the second intermediate layer 6 have the same configuration as the first intermediate layer 5 and the second intermediate layer 6 described in Embodiment 6. The wafer holder 1 of Embodiment 8 differs from Embodiment 7 in the configuration of the intermediate layer 4.

[0093] [Example Test] In the test example, the combined thermal expansion coefficient of the first resin layer 3 and the intermediate layer 4 was investigated to affect the delamination of the first resin layer 3 from the substrate 2 in the wafer holder 1 of Embodiment 6 shown in Figure 7.

[0094] <Description of the test specimen> Multiple test specimens were prepared with different combined thermal expansion coefficients of the first resin layer 3 and the intermediate layer 4. In each test specimen, the first intermediate layer 5, the second intermediate layer 6, and the first resin layer 3 are sequentially laminated on the first surface 21 of the substrate 2. In each test specimen, a metal layer 7 is placed between the first intermediate layer 5 and the second intermediate layer 6.

[0095] In all test specimens, the material and thickness of substrate 2 are the same. Substrate 2 is made of ceramics. The thermal expansion coefficient of substrate 2 is 2.8 ppm / K. The thickness of substrate 2 is 3 mm.

[0096] The material of the first resin layer 3 is the same in all test specimens. The first resin layer 3 is made of polyimide resin. The first resin layer 3 is a single layer. The thermal expansion coefficient Ka of the first resin layer 3 is 3.0 ppm / K or 20.0 ppm / K. The thickness Ta of the first resin layer 3 is as shown in Table 1.

[0097] In all test specimens, the composition and materials are the same except for the thickness of the intermediate layer 4. The intermediate layer 4 consists of a first intermediate layer 5 and a second intermediate layer 6. The first intermediate layer 5 and the second intermediate layer 6 are made of polyimide resin. Each of the first intermediate layer 5 and the second intermediate layer 6 has a three-layer structure in which the resin layer is placed between two adhesive layers. In other words, the intermediate layer 4 has a six-layer structure. The two adhesive layers are made of thermoplastic polyimide resin. The thermal expansion coefficient Kb of the intermediate layer 4, consisting of the first intermediate layer 5 and the second intermediate layer 6, is 20 ppm / K. The total thickness of the first intermediate layer 5 and the second intermediate layer 6, i.e., the thickness Tb of the intermediate layer 4, is as shown in Table 1. In all test specimens, multiple metal layers 7 are dispersed between the first intermediate layer 5 and the second intermediate layer 6. When determining the combined thermal expansion coefficient of the first resin layer 3 and the intermediate layer 4, the thickness and thermal expansion coefficient of the metal layers 7 are ignored.

[0098] In specimens 1 through 5, and in specimen 7, the difference between the thermal expansion coefficient of the first resin layer 3 and the thermal expansion coefficient of the substrate 2 is 0.2 ppm / K. In specimen 6, the difference between the thermal expansion coefficient of the first resin layer 3 and the thermal expansion coefficient of the substrate 2 is 17.2 ppm / K. The combined thermal expansion coefficient of the first resin layer 3 and the intermediate layer 4, and the difference between this combined thermal expansion coefficient and the thermal expansion coefficient of the substrate 2 are shown in Table 1. The combined thermal expansion coefficient is calculated using the formula (Ka × Ta + Kb × Tb) / (Ta + Tb).

[0099] <Testing Method> A heater component was placed on the second surface of the substrate 2 in each test specimen, and a heat cycle test was performed. In the heat cycle test, the process of raising the temperature from 200°C to 250°C and then lowering the temperature from 250°C to 200°C was repeated 1000 times. The heating rate was 1°C / sec. The holding time at 250°C was 5 minutes. The cooling rate was 1°C / sec. The holding time at 200°C was 10 minutes. After the heat cycle test, the temperature of each test specimen was lowered to room temperature, and the presence or absence of delamination of the first resin layer 3 from the substrate 2 was visually checked. The results are shown in Table 1. "A" in Table 1 indicates that the first resin layer 3 has not delaminated from the substrate 2. "B" in Table 1 indicates that the first resin layer 3 has delaminated from the substrate 2. Note that even if there is only a very slight delamination of the first resin layer 3 from the entire surface of the substrate 2, it is evaluated as delamination of the first resin layer 3.

[0100] [Table 1]

[0101] As shown in Table 1, in test specimens 1 to 5, where the difference between the thermal expansion coefficient of the first resin layer 3 and the thermal expansion coefficient of the substrate 2 was 3 ppm / K or less, and the difference between the combined thermal expansion coefficient of the first resin layer 3 and the intermediate layer 4 and the thermal expansion coefficient of the substrate 2 was 16 ppm / K or less, the first resin layer 3 did not peel off from the substrate 2 even after being subjected to a heat cycle. In test specimen 6, the difference between the thermal expansion coefficient of the first resin layer 3 and the thermal expansion coefficient of the substrate 2 was greater than 3 ppm / K, and the difference between the above combined thermal expansion coefficient and the thermal expansion coefficient of the substrate 2 was greater than 16 ppm / K, and the first resin layer 3 peeled off significantly from the substrate 2. In test specimen 7, the difference between the thermal expansion coefficient of the first resin layer 3 and the thermal expansion coefficient of the substrate 2 was 3 ppm / K, but the difference between the combined thermal expansion coefficient and the thermal expansion coefficient of the substrate 2 was 16.4 ppm / K. Although the first resin layer 3 had delaminated from the substrate 2, the proportion of the area where the first resin layer 3 delaminated relative to the total area of ​​the substrate 2 was very small. [Explanation of Symbols]

[0102] 1 Wafer holder 2 Base 21 first side, 210 unevenness, 22 second side 3 First resin layer 30 protrusions, 30H height 31 First protrusion, 32 Second protrusion 4. Middle Class 5 First middle layer 50 second resin layer, 51 first adhesive layer, 52 second adhesive layer 6 Second middle layer 60 Third resin layer, 61 Third adhesive layer, 62 Fourth adhesive layer 7 metal layers, 7T thickness 300 Daiichi Resin Film 500 Second resin film, 510 First layer, 511, 512 Second layer 600 Third resin film, 610 First layer, 611, 612 Second layer 700 Metal Film 800 cushioning material Ta, Tb thickness D1 First direction

Claims

1. A plate-shaped substrate, A first resin layer laminated on the first surface of the substrate, An intermediate layer provided between the substrate and the first resin layer, The system comprises one or more metal layers disposed between the substrate and the intermediate layer or inside the intermediate layer, The surface roughness of the first surface is 1 μm or more and 10 μm or less in terms of arithmetic mean roughness Ra. The aforementioned intermediate layer includes a first adhesive layer, a second resin layer, and a second adhesive layer. The first adhesive layer is in contact with the first surface, The second resin layer is provided between the first adhesive layer and the second adhesive layer. The metal layer is arranged in a plane parallel to the first surface, The substrate is formed of ceramics or a composite containing ceramics. The first resin layer is formed of polyimide resin, The first adhesive layer and the second adhesive layer are formed of thermoplastic polyimide resin. The difference between the thermal expansion coefficient of the first resin layer and the thermal expansion coefficient of the substrate is 3 ppm / K or less. The thermal expansion coefficient of the intermediate layer is greater than that of the first resin layer. The difference between the combined thermal expansion coefficient of the first resin layer and the intermediate layer and the thermal expansion coefficient of the substrate is 16 ppm / K or less. The aforementioned combined thermal expansion coefficient is calculated as (Ka × Ta + Kb × Tb) / (Ta + Tb), Ka is the thermal expansion coefficient of the first resin layer, Kb is the thermal expansion coefficient of the intermediate layer, Ta is the thickness of the first resin layer, Tb is the thickness of the intermediate layer, The units for Ka and Kb are ppm / K. The units of Ta and Tb are μm. Wafer holder.

2. The aforementioned metal layer is multiple, The plurality of metal layers are dispersed and arranged within the plane. The wafer holder according to claim 1, wherein the surface of the first resin layer is provided with a plurality of protrusions in the portion corresponding to the location where the plurality of metal layers are arranged.

3. The aforementioned intermediate layer further comprises a third adhesive layer, a third resin layer, and a fourth adhesive layer. The third adhesive layer is in contact with the second adhesive layer. The third resin layer is provided between the third adhesive layer and the fourth adhesive layer. The wafer holder according to claim 1 or claim 2, wherein the third adhesive layer and the fourth adhesive layer are formed of a thermoplastic polyimide resin.

4. The wafer holder according to claim 1, wherein the metal layer is a heating element.

5. A process of preparing a first resin film, a second resin film, a third resin film, a metal film, and a substrate, The process includes the step of sequentially laminating the second resin film, the metal film, the third resin film, and the first resin film on the first surface of the substrate, The surface roughness of the first surface is 1 μm or more and 10 μm or less in terms of arithmetic mean roughness Ra. The substrate is formed of ceramics or a composite containing ceramics. The first resin film is formed of polyimide resin, Each of the second resin film and the third resin film comprises a first layer and two second layers laminated on the first layer so as to sandwich the first layer, At least the two second layers are formed of thermoplastic polyimide resin, The difference between the thermal expansion coefficient of the first resin film and the thermal expansion coefficient of the substrate is 3 ppm / K or less. The thermal expansion coefficient of the intermediate film is greater than that of the first resin film. The difference between the combined thermal expansion coefficient of the first resin film and the intermediate film and the thermal expansion coefficient of the substrate is 16 ppm / K or less. The intermediate film consists of the second resin film and the third resin film. The aforementioned combined thermal expansion coefficient is calculated as (Ka × Ta + Kb × Tb) / (Ta + Tb), Ka is the thermal expansion coefficient of the first resin film, Kb is the thermal expansion coefficient of the intermediate film, Ta is the thickness of the first resin film, Tb is the thickness of the intermediate film, The units for Ka and Kb are ppm / K. The units of Ta and Tb are μm. A method for manufacturing a wafer holder.

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