Substrate holder

Abstract

To provide a substrate holder excellent in thermal uniformity.SOLUTION: A placing plate having an upper surface on which a substrate is placed, a sheet-shaped heater, and a support plate in this order, wherein the heater has a wiring pattern, a dummy pattern separated from the wiring pattern in the same plane as the wiring pattern, and an insulating layer covering the wiring pattern and the dummy pattern, the dummy pattern has a plurality of dummy portions, and a material of the dummy pattern is different from a material of the insulating layer, when the heater is viewed from the upper surface, a ratio of a total area of an area of the wiring pattern and an area of the dummy pattern to an effective area of the insulating layer is 60% or more, a maximum length L of each of the dummy portions satisfies L ≤ 40 / ((x-y) * Δ T), x is a linear expansion coefficient of a material of the dummy pattern, y is a linear expansion coefficient of a material of the insulating layer, and Δ T is an operating temperature range of the heater.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a substrate holder. [Background technology]

[0002] Patent Document 1 discloses a wafer heater unit that includes a mounting table having a wafer mounting surface, a resistance heating unit disposed on the surface opposite the wafer mounting surface, and a support plate that supports the mounting table and the resistance heating unit. This resistance heating unit includes a heating element, an intervening material disposed between the heating element patterns, and an insulating layer disposed between the heating element and the mounting table. The heating element is a metal foil such as stainless steel. Hereinafter, the "wafer heater unit" will be referred to as the "substrate holder" and the "resistance heating unit" as the "heater." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-222256 Summary of the Invention [Problem to be solved by the invention]

[0004] When a heating object such as a semiconductor substrate is heated by a substrate holder, uniform heating is required.

[0005] Generally, a substrate holder includes a mounting plate, a heater, and a support plate. The substrate holder heats the mounting plate with the heater, thereby heating an object placed on the upper surface of the mounting plate. A heater, in which a wiring pattern forming a heat-generating circuit is covered with an insulating layer, has different thicknesses in different parts. The thickness of the heater in the part with the wiring pattern is the combined thickness of the wiring pattern and the insulating layer. The thickness of the heater in the part without the wiring pattern is the thickness of the insulating layer alone. In other words, the part without the wiring pattern is thinner than the part with the wiring pattern. For this reason, recesses are formed on both sides of the heater in the part without the wiring pattern. If there is a recess on the surface of the heater, the heater and the mounting plate do not come into close contact, and a gap is created in the recess. This gap prevents the heat from the heater from being transferred evenly to the mounting plate, making it difficult to achieve a uniform temperature distribution on the upper surface of the mounting plate.

[0006] An object of the present disclosure is to provide a substrate holder with excellent thermal uniformity. [Means for solving the problem]

[0007] The substrate holder of the present disclosure comprises, in this order, a mounting plate having an upper surface on which a substrate is placed, a sheet-like heater, and a support plate. The heater has a wiring pattern forming a heat-generating circuit, a dummy pattern separated from the wiring pattern on the same plane as the wiring pattern, and an insulating layer covering the wiring pattern and the dummy pattern. The dummy pattern has a plurality of dummy portions arranged apart from each other. The material of the dummy pattern is different from the material of the insulating layer. When the heater is viewed from the top, the ratio of the total area of ​​the wiring pattern and the area of ​​the dummy pattern to the effective area of ​​the insulating layer is 60% or more. The maximum length L of each of the dummy portions satisfies L≦40 / ((xy)×ΔT), where x is the linear expansion coefficient of the material of the dummy pattern, y is the linear expansion coefficient of the material of the insulating layer, and ΔT is the operating temperature range of the heater. [Effects of the Invention]

[0008] The substrate holder of the present disclosure has excellent thermal uniformity. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view of a substrate holder according to the first embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view showing an enlarged portion of a heater provided in the substrate holder according to the first embodiment. [Figure 3] FIG. 3 is a schematic plan view of a heater provided on the substrate holder according to the first embodiment. [Figure 4] FIG. 4 is a schematic plan view of the wiring pattern shown in FIG. [Figure 5] FIG. 5 is a schematic plan view of the dummy pattern shown in FIG. [Figure 6] FIG. 6 is a schematic plan view of the insulating layer shown in FIG. [Figure 7] FIG. 7 is a schematic cross-sectional view for explaining the maximum length of the dummy portion of the dummy pattern. [Figure 8] FIG. 8 is a schematic cross-sectional view of a substrate holder according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The inventors conducted research into substrate holders capable of uniformly heating a heating target and discovered the following. As with the technology disclosed in Patent Document 1, the heater surface can be made flat by placing a dummy pattern as an inclusion in areas without a wiring pattern. However, with substrate holders, the flatness of the heater surface can be impaired over time. When the wiring pattern generates heat, the dummy pattern and the insulating layer rise in temperature. If the dummy pattern and the insulating layer have different thermal expansion rates, the insulating layer on the dummy pattern deforms due to the difference in thermal expansion, causing wrinkles on the heater surface. In particular, the longer the dummy pattern, the greater the difference in thermal expansion between the dummy pattern and the insulating layer, resulting in larger wrinkles. Wrinkles on the heater surface degrade the flatness of the heater surface. This can impair adhesion between the heater and the mounting plate, potentially resulting in poor heating uniformity.

[0011] [Description of the embodiments of the present disclosure] The present disclosure has been made in light of the above findings. First, embodiments of the present disclosure will be listed and described.

[0012] (1) A substrate holder according to the present disclosure comprises, in this order, a mounting plate having an upper surface on which a substrate is placed, a sheet-like heater, and a support plate. The heater has a wiring pattern forming a heat-generating circuit, a dummy pattern separated from the wiring pattern on the same plane as the wiring pattern, and an insulating layer covering the wiring pattern and the dummy pattern. The dummy pattern has a plurality of dummy portions arranged apart from each other. The material of the dummy pattern is different from the material of the insulating layer. When the heater is viewed from the top, the ratio of the total area of ​​the wiring pattern and the dummy pattern to the effective area of ​​the insulating layer is 60% or more. The maximum length L of each of the dummy portions satisfies L≦40 / ((xy)×ΔT), where x is the linear expansion coefficient of the material of the dummy pattern, y is the linear expansion coefficient of the material of the insulating layer, and ΔT is the operating temperature range of the heater.

[0013] By arranging the dummy pattern in the same plane as the wiring pattern, the surface of the heater can be made flat. Also, by making the ratio of the total area of ​​the wiring pattern and the dummy pattern to the effective area of ​​the insulating layer 60% or more, the flatness of the heater surface can be improved. Furthermore, by making the maximum length L of the dummy portion satisfy the above formula, the flatness of the heater surface can be maintained at 20 μm or less. Therefore, the substrate holder of the present disclosure has excellent thermal uniformity.

[0014] (2) In the substrate holder of (1) above, the dummy patterns may be made of a metal.

[0015] The dummy pattern is made of a metal material, which can improve the thermal conductivity of the heater.

[0016] (3) In the substrate holder of (1) or (2) above, the material of the dummy pattern may be the same as the material of the wiring pattern.

[0017] By using the same material for the dummy pattern as for the wiring pattern, the wiring pattern and the dummy pattern can be formed simultaneously, and material waste for the wiring pattern and the dummy pattern is reduced.

[0018] (4) In any of the substrate holders (1) to (3) above, the maximum length L may be 50 mm or less.

[0019] By setting the maximum length L of the dummy portion to 50 mm or less, the flatness of the heater surface is easily maintained.

[0020] (5) In the substrate holder of any one of (1) to (4) above, the distance between adjacent dummy portions may be 2 mm or less.

[0021] By setting the distance between the dummy portions to 2 mm or less, the thermal conductivity of the heater may be improved.

[0022] (6) In the substrate holder of any one of (1) to (5) above, the distance between the wiring pattern and the dummy portion adjacent to the wiring pattern may be 1 mm or more.

[0023] By setting the distance between the wiring pattern and the dummy part to 1 mm or more, a sufficient insulating distance can be maintained between the wiring pattern and the dummy part. If the dummy part is made of metal, current can be prevented from flowing from the wiring pattern to the dummy part.

[0024] (7) In any one of the substrate holders (1) to (6) above, the insulating layer may be made of polyimide.

[0025] An insulating layer formed from polyimide has excellent heat resistance and high tensile strength. The heat resistance of the insulating layer makes it less likely to be damaged by heat generated by the wiring pattern. Furthermore, the high tensile strength of the insulating layer makes it possible to restrict the elongation of the wiring pattern due to thermal expansion. Therefore, the wiring pattern is less likely to become misaligned due to thermal expansion.

[0026] [Details of the embodiments of the present disclosure] Specific examples of substrate holders according to embodiments of the present disclosure will be described below with reference to the drawings. The same reference numerals in the drawings indicate the same or corresponding parts. The drawings are schematic, and the dimensions of the components shown in the drawings do not necessarily correspond to the actual dimensions. It should be noted that 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 equivalent to the claims.

[0027] <Substrate holder> The substrate holder of the embodiment is used, for example, in semiconductor manufacturing equipment and inspection equipment. For example, in semiconductor inspection, electrical performance of the semiconductor substrate is measured while the temperature is controlled to a predetermined value. The substrate holder of the embodiment can also be used for purposes other than inspection equipment.

[0028] [Embodiment 1] The structure of a substrate holder 1 of embodiment 1 will be described with reference to FIGS. 1 to 7. The substrate holder 1 includes a mounting plate 2, a heater 3, and a support plate 5, in this order. The mounting plate 2, heater 3, and support plate 5 are arranged from top to bottom on the substrate holder 1. "Arranged in this order" means that the mounting plate 2, heater 3, and support plate 5 only need to be arranged in this order, and other components may be present between each component. The substrate holder 1 is a device that heats a substrate 100 placed on the upper surface 20 of the mounting plate 2 to a predetermined temperature using a heater 3. The substrate holder 1 is supported by a pedestal 7, which will be described later. One of the features of the substrate holder 1 is that the heater 3 has a specific configuration. The components of the substrate holder 1 will be described in detail below. FIG. 1 is a schematic cross-sectional view of the substrate holder 1. FIG. 1 also shows the heater 3, as well as the arrangement of a fastening member 6 and support posts 71, which will be described later.

[0029] <Substrate> The substrate 100 is, for example, a semiconductor substrate. The shape of the substrate 100 is, for example, a disk or a rectangular plate. In other words, the planar shape of the substrate 100 when viewed from above is a circle or a polygon. The substrate 100 in this example is a quadrangular plate-shaped semiconductor substrate. The planar shape of the substrate 100 is a quadrangle. A quadrangle is, for example, a square or a rectangle. The size of the substrate 100 is, for example, such that one side is 200 mm or more and 400 mm or less.

[0030] <Placement plate> The mounting plate 2 is a member on which the substrate 100 is placed. The mounting plate 2 has an upper surface 20 and a lower surface 21. The upper surface 20 is the surface on which the substrate 100 is placed. The lower surface 21 is the surface opposite the upper surface 20.

[0031] The shape of the mounting plate 2 is, for example, a disk or a rectangular plate. In other words, the planar shape of the mounting plate 2 when viewed from the top surface 20 is a circle or a polygon. The planar shape of the mounting plate 2 is a shape that matches the planar shape of the substrate 100. In this example, the shape of the mounting plate 2 is a square plate. In other words, the planar shape of the mounting plate 2 is a square. The size of the mounting plate 2 is slightly larger than the substrate 100. The size of the mounting plate 2 is, for example, such that one side is 210 mm or more and 410 mm or less. For example, if one side of the substrate 100 is 300 mm, one side of the mounting plate 2 is 310 mm. The size of the mounting plate 2 is the dimension in a plane parallel to the top surface 20.

[0032] The thickness of the mounting plate 2 is, for example, 5 mm to 25 mm, and further 7 mm to 20 mm. The thickness of the mounting plate 2 is the dimension of the mounting plate 2 along a direction perpendicular to the upper surface 20. If the thickness of the mounting plate 2 is 5 mm or more, the rigidity of the mounting plate 2 is high. If the thickness of the mounting plate 2 is 25 mm or less, the heat of the heater 3 is easily transferred to the upper surface 20.

[0033] The mounting plate 2 is made of a material with excellent thermal conductivity and high rigidity. The material of the mounting plate 2 is, for example, a metal, ceramic, or ceramic-containing composite. The metal forming the mounting plate 2 is, for example, copper, copper alloy, aluminum, or aluminum alloy. The ceramic forming the mounting plate 2 is, for example, silicon carbide, aluminum nitride, aluminum oxide, or silicon nitride. The ceramic-containing composite forming the mounting plate 2 is, for example, a silicon-silicon carbide composite, an aluminum-silicon carbide composite, or an aluminum-silicon-silicon carbide composite. The above metals have high thermal conductivity. If the mounting plate 2 is made of the above metal, the mounting plate 2 easily conducts heat. Therefore, the substrate 100 can be heated efficiently. The above ceramics or ceramic-containing composites have higher rigidity than metals. If the mounting plate 2 is made of the above ceramics or ceramic-containing composite, the mounting plate 2 is less likely to deform. Therefore, the thickness of the mounting plate 2 can be reduced. The material of the mounting plate 2 in this example is a composite of silicon and silicon carbide (Si—SiC).

[0034] The thermal conductivity of the support plate 2 is, for example, 100 W / m·K or more. The thermal conductivity of the support plate 2 may further be 200 W / m·K or more, 300 W / m·K or more, or 400 W / m·K or more. These thermal conductivities are values ​​at 20°C. The thermal conductivity of copper is approximately 400 W / m·K, and the thermal conductivity of aluminum is approximately 230 W / m·K. The thermal conductivity of silicon carbide is approximately 200 W / m·K, the thermal conductivity of aluminum nitride is approximately 150 W / m·K, the thermal conductivity of aluminum oxide is approximately 30 W / m·K, the thermal conductivity of silicon nitride is approximately 30 W / m·K, and the thermal conductivity of Si-SiC is approximately 170 W / m·K.

[0035] The surface of the mounting plate 2 may be subjected to a surface treatment. The surface treatment is, for example, plating. Specific examples of plating are nickel plating or nickel-phosphorus plating. The plating method is electrolytic plating or electroless plating.

[0036] Although not shown here, the mounting plate 2 may be provided with a chuck mechanism that adsorbs the substrate 100 onto the upper surface 20. Adsorption of the substrate 100 onto the upper surface 20 corrects warpage of the substrate 100. Adhesion of the entire substrate 100 to the upper surface 20 makes it easier for the entire substrate 100 to be heated uniformly.

[0037] Furthermore, a temperature sensor (not shown) may be provided on the mounting plate 2. This temperature sensor measures the temperature of the mounting plate 2. The temperature of the heater 3 is controlled based on the temperature of the mounting plate 2 measured by the temperature sensor. When the substrate holder 1 includes a cooling plate 8 shown in FIG. 8 (to be described later), the temperature sensor may be provided on the cooling plate 8.

[0038] <Heater> The heater 3 heats the substrate 100 by heating the mounting plate 2. The heater 3 is sheet-shaped. When viewed from above, the heater 3 has a circular or polygonal planar shape. The planar shape of the heater 3 matches the planar shape of the mounting plate 2. In this example, the planar shape of the heater 3 is a square. The size of the heater 3 is the same as the size of the mounting plate 2.

[0039] The heater 3 is disposed on the lower surface 21 of the mounting plate 2. The heater 3 is supported by a support plate 5. In this example, the heater 3 is sandwiched between a first insulating sheet 41 and a second insulating sheet 42, which will be described later. That is, from top to bottom, the first insulating sheet 41, the heater 3, and the second insulating sheet 42 are disposed. The first insulating sheet 41 is disposed between the heater 3 and the mounting plate 2. The second insulating sheet 42 is disposed between the heater 3 and the support plate 5. The first insulating sheet 41 and the second insulating sheet 42 are not essential.

[0040] As shown in FIGS. 2 and 3 , the heater 3 includes a wiring pattern 30, a dummy pattern 31, and an insulating layer 32. FIG. 2 is a schematic cross-sectional view of a portion of the heater 3. FIG. 3 is a plan view of the heater 3 seen through the upper surface 20 of the mounting plate 2 shown in FIG. 1 . The wiring pattern 30 and the dummy pattern 31 are arranged on the same plane. As shown in FIG. 3 , in a plan view of the heater 3 seen from above, the dummy pattern 31 is provided in an area that does not overlap with the wiring pattern 30. In FIG. 3 , the dummy pattern 31 is hatched for clarity. The two-dot chain line in FIG. 3 indicates the effective area of ​​the insulating layer 32, which will be described later. In this example, the dummy pattern 31 and the wiring pattern 30 are separated from each other and do not contact each other. As shown in FIG. 2 , the wiring pattern 30 and the dummy pattern 31 are covered with the insulating layer 32. The insulating layer 32 has a first insulating layer 32a and a second insulating layer 32b. The wiring pattern 30 and the dummy pattern 31 are sandwiched between a first insulating layer 32a and a second insulating layer 32b. In this example, the first insulating layer 32a and the second insulating layer 32b are bonded together. The dashed lines in FIG. 2 represent the interface between the first insulating layer 32a and the second insulating layer 32b. The first insulating layer 32a contacts the upper surfaces of the wiring pattern 30 and the dummy pattern 31, respectively. The second insulating layer 32b contacts the lower surfaces of the wiring pattern 30 and the dummy pattern 31, respectively.

[0041] 4 to 6 show the wiring pattern 30, dummy pattern 31, and insulating layer 32 shown in FIG. 3 individually. In FIG. 4, only the wiring pattern 30 is shown by a solid line. In FIG. 5, only the dummy pattern 31 is shown by a solid line. In FIG. 6, only the insulating layer 32 is shown by a solid line. In FIGS. 4 and 5, the insulating layer 32 is shown by a two-dot chain line.

[0042] [Wiring pattern] The wiring pattern 30 is arranged in a plane parallel to the upper surface 20 of the mounting plate 2. The wiring pattern 30 forms a heat-generating circuit. The wiring pattern 30 is designed to maintain a uniform temperature distribution on the upper surface 20 when the mounting plate 2 is heated by the heater 3. The wiring pattern 30 has a pair of terminals 30t, as shown in FIG. 4. In this example, the pair of terminals 30t are arranged near the center of the heater 3. Each terminal 30t is connected to a terminal of a power line (not shown). The wiring pattern 30 is formed by drawing a heating element linearly from one terminal 30t, drawing a uniform line across roughly the entire surface of the heater 3, and connecting to the remaining terminal 30t. The wiring pattern 30 in this example is provided symmetrically. The shape of the wiring pattern 30 is not limited to this example, and other shapes may be used as long as the heating element can be uniformly arranged across roughly the entire surface of the heater 3.

[0043] <material> The wiring pattern 30 is formed by a heating element. A heating element is a material that generates heat when a current flows through it. The heating element is, for example, a metal such as stainless steel or nickel-chromium steel. When a current flows through the wiring pattern 30, the wiring pattern 30 heats up and heat is generated from the heater 3. The wiring pattern 30 in this example is formed by processing a metal foil into a predetermined shape. The processing of the metal foil is, for example, etching or laser processing. The wiring pattern 30 in this example is processed from a stainless steel foil.

[0044] <Thickness> The thickness of the wiring pattern 30 may be any thickness that provides an appropriate amount of heat when a current flows through the wiring pattern 30. The thickness of the wiring pattern 30 is, for example, 0.01 mm to 0.5 mm, or even 0.02 mm to 0.1 mm. In this example, the thickness of the wiring pattern 30 is 0.05 mm.

[0045] [Dummy pattern] As shown in Fig. 3, the dummy pattern 31 is separated from the wiring pattern 30. In other words, the wiring pattern 30 and the dummy pattern 31 are not connected. The dummy pattern 31 does not generate heat even when a current flows through the wiring pattern 30. As shown in Fig. 5, the dummy pattern 31 is divided into a plurality of dummy portions 31d. The plurality of dummy portions 31d are arranged apart from each other.

[0046] As shown in FIG. 2, the dummy pattern 31 is disposed in a portion of the same plane as the wiring pattern 30 where the wiring pattern 30 is not present. Without the dummy pattern 31, the first insulating layer 32a and the second insulating layer 32b are in contact with each other in the portion where the wiring pattern 30 is not present. The surface of the heater 3 in the portion where the wiring pattern 30 is not present is depressed compared to the surface of the heater 3 in the portion where the wiring pattern 30 is present, which may result in the formation of recesses on both sides of the heater 3. In particular, the greater the spacing between the wiring patterns 30, the more likely the surface of the heater 3 is to be depressed, and the more likely recesses are to be formed on both sides of the heater 3. When the dummy pattern 31 is present, the dummy pattern 31 is inserted into the gaps between the wiring patterns 30, thereby preventing the surface of the heater 3 from being depressed. Since recesses are less likely to be formed on both sides of the heater 3, both sides of the heater 3 can be made flat.

[0047] The planar shape of each dummy portion 31d can be appropriately selected so as to fill as much of the areas that do not overlap with the wiring pattern 30 and the through-holes of the insulating layer 32 described below. The planar shape of the dummy portion 31d is, for example, a polygon such as a triangle, a rectangle, or a hexagon. The quadrilateral shape includes a square, a rectangle, a trapezoid, a rhombus, and a parallelogram. Alternatively, the planar shape of the dummy portion 31d may be a closed figure formed of curved lines such as a circle or an ellipse, or may be a closed figure formed by combining straight lines and curved lines.

[0048] <material> The dummy pattern 31 is formed of a material different from that of the insulating layer 32. The material of the dummy pattern 31 may be a conductive material such as metal, or an insulating material such as resin, ceramics, or glass, as long as it is different from the material of the insulating layer 32. The material of the dummy pattern 31 preferably has a higher thermal conductivity than the material of the insulating layer 32. When the dummy pattern 31 has a high thermal conductivity, the thermal conductivity of the heater 3 can be improved.

[0049] Generally, metal has a higher thermal conductivity than resin. When the material of the dummy pattern 31 is metal, the thermal conductivity of the heater 3 can be improved compared to when the material of the dummy pattern 31 is resin. The metal forming the dummy pattern 31 is, for example, copper, copper alloy, aluminum, aluminum alloy, iron, or iron alloy.

[0050] The material of the dummy pattern 31 may be the same as the material of the wiring pattern 30. That is, the material of the dummy pattern 31 may be a metal such as stainless steel or nickel-chromium steel. If the material of the dummy pattern 31 is the same as the material of the wiring pattern 30, the wiring pattern 30 and the dummy pattern 31 can be formed simultaneously when forming the wiring pattern 30. Furthermore, material waste of the wiring pattern 30 and the dummy pattern 31 is reduced. In this example, the dummy pattern 31 is formed from the same metal foil as the wiring pattern 30. In this example, the dummy pattern 31 is formed from processed stainless steel foil. The method of forming the wiring pattern 30 and the dummy pattern 31 will be described in detail in the section <Heater Manufacturing Method> below.

[0051] The wiring pattern 30 and the dummy pattern 31 may be arranged with a gap between them. By separating the dummy pattern 31 from the wiring pattern 30, it is easy to prevent the current flowing through the wiring pattern 30 from flowing through the dummy pattern 31. Therefore, even if the material of the dummy pattern 31 is metal, it is possible to prevent the dummy pattern 31 from generating heat.

[0052] When the material of the dummy pattern 31 is an insulating material such as resin, the wiring pattern 30 and the dummy portion 31d may be in contact with each other. If the material of the dummy pattern 31 is an insulating material, no current flows from the wiring pattern 30 to the dummy pattern 31, and the dummy pattern 31 does not generate heat.

[0053] <Thickness> The thickness of the dummy pattern 31 is substantially the same as the thickness of the wiring pattern 30. "Substantially the same" not only means that the thickness of the wiring pattern 30 and the thickness of the dummy pattern 31 are the same, but also includes the case where the difference in thickness between the wiring pattern 30 and the dummy pattern 31 is 20 μm or less. By making the thickness of the wiring pattern 30 and the thickness of the dummy pattern 31 substantially the same, both surfaces of the heater 3 can be made almost flat. The thickness of the dummy pattern 31 is, for example, 0.01 mm or more and 0.5 mm or less, or even 0.02 mm or more and 0.1 mm or less. In this example, the thickness of the dummy pattern 31 is 0.05 mm.

[0054] [Insulating layer] The insulating layer 32 covers the wiring pattern 30 and the dummy pattern 31 from both sides. The insulating layer 32 electrically insulates the wiring pattern 30 and mechanically protects the wiring pattern 30 and the dummy pattern 31. The wiring pattern 30 is arranged so as not to protrude from the insulating layer 32. As shown in FIG. 3, the size of the insulating layer 32 is slightly larger than the size of the wiring pattern 30. Specifically, the insulating layer 32 has a size larger than the outermost outline of the wiring pattern 30. The planar shape of the insulating layer 32 in this example is rectangular.

[0055] The insulating layer 32 may be provided with various through holes as shown in Fig. 6. The fastening member 6 shown in Fig. 1 is inserted through the through hole 36h. The support post 71 shown in Fig. 1 is inserted through the through hole 37h. The through hole 38h is provided at the position of the terminal 30t of the wiring pattern 30 shown in Fig. 4. A terminal of a power line (not shown) connected to the terminal 30t is disposed in the through hole 38h.

[0056] <material> The insulating layer 32 is formed from an insulating resin that has excellent heat resistance and high tensile strength. The heat resistance temperature of the insulating layer 32 is, for example, 200°C or higher. If the heat resistance temperature of the insulating layer 32 is 200°C or higher, the insulating layer 32 is less likely to be damaged by heat generated in the wiring pattern 30. The heat resistance temperature of the insulating layer 32 may be 210°C or higher. The high tensile strength of the insulating layer 32 can restrict the elongation of the wiring pattern 30 due to thermal expansion. Therefore, displacement of the wiring pattern 30 due to thermal expansion is less likely to occur. The tensile strength of the insulating layer 32 is, for example, 100 MPa or higher. The material of the insulating layer 32 is, for example, polyimide. In this example, the insulating layer 32 is formed from a polyimide film.

[0057] <Thickness> The thickness of the insulating layer 32, i.e., the thickness of each of the first insulating layer 32a and the second insulating layer 32b, is, for example, 0.01 mm to 1 mm, or even 0.02 mm to 0.1 mm. Having a thickness of 0.01 mm or more facilitates electrical insulation of the wiring pattern 30 and mechanical protection of the wiring pattern 30 and the dummy pattern 31. Having a thickness of 1 mm or less for the insulating layer 32 reduces the thickness of the heater 3. This allows the heater 3 to be thinned and installed in the limited space of the substrate holder 1. Furthermore, having a thickness of 1 mm or less for the insulating layer 32 facilitates dissipation of heat generated in the wiring pattern 30. This reduces excessive temperature rise in the wiring pattern 30 and makes it less likely for the wiring pattern 30 to become abnormally hot. The thickness of the insulating layer 32 may be 0.01 mm to 0.5 mm, or even 0.05 mm to 0.5 mm. If the thickness of the insulating layer 32 is 0.05 mm or more, it is easy to reliably provide electrical insulation and mechanical protection for the wiring pattern 30. If the thickness of the insulating layer 32 is 0.5 mm or less, heat dissipation from the wiring pattern 30 is more efficient. The thickness of the first insulating layer 32a and the thickness of the second insulating layer 32b may be the same or different. The thickness of the insulating layer 32 in this example is 0.05 mm.

[0058] The first insulating layer 32a and the second insulating layer 32b are bonded by adhesive or fusion. In the portion where the wiring pattern 30 or the dummy pattern 31 is present, the first insulating layer 32a is bonded to the upper side of the wiring pattern 30 or the upper side of the dummy pattern 31, and the second insulating layer 32b is bonded to the lower side of the wiring pattern 30 or the lower side of the dummy pattern 31. Part of the first insulating layer 32a and part of the second insulating layer 32b fill the gap between the wiring pattern 30 and the dummy pattern 31 and the gap between adjacent dummy portions 31d.

[0059] <Heater manufacturing method> The heater 3 can be manufactured, for example, as follows: A metal foil is bonded to one side of a polyimide film that will become the second insulating layer 32b. The metal foil is, for example, stainless steel foil. The area of ​​the metal foil is, for example, the same as the area of ​​the polyimide film. Next, at least the wiring pattern 30 is formed from the metal foil. For example, a mask for the wiring pattern 30 and dummy pattern 31 is formed on the metal foil, and the metal foil is then etched to form the wiring pattern 30 and dummy pattern 31. The unmasked portions of the metal foil are removed by etching, thereby forming the wiring pattern 30 and dummy pattern 31 on the polyimide film that will become the second insulating layer 32b. A polyimide film that will become the first insulating layer 32a is superimposed on the wiring pattern 30 and dummy pattern 31. The heater 3 is manufactured by bonding the first insulating layer 32a and the second insulating layer 32b together with the wiring pattern 30 and dummy pattern 31 sandwiched between them. In this heater 3, the wiring pattern 30 and the dummy pattern 31 are formed from the same metal foil.

[0060] When bonding the first insulating layer 32a and the second insulating layer 32b, the first insulating layer 32a and the second insulating layer 32b are pressed against the wiring pattern 30 and the dummy pattern 31 to bond them together. This causes the first insulating layer 32a and the second insulating layer 32b to flow, and parts of the first insulating layer 32a and the second insulating layer 32b enter the gap between the wiring pattern 30 and the dummy pattern 31 and the gap between adjacent dummy portions 31d. If the gap is 0.5 mm or more, parts of the first insulating layer 32a and the second insulating layer 32b tend to enter the gap.

[0061] The heater 3, in which the wiring pattern 30 and the dummy pattern 31 are formed from different materials, can be manufactured, for example, as follows: A metal foil that will form the wiring pattern 30 is bonded to one side of a polyimide film that will form the second insulating layer 32b. A mask for the wiring pattern 30 is formed on the metal foil, and the metal foil is then etched to form the wiring pattern 30. A material that will form the dummy pattern 31 is bonded to one side of a polyimide film that will form the first insulating layer 32a. For example, if the dummy pattern 31 is made of copper, copper foil is used as the material for the dummy pattern 31. A mask for the dummy pattern 31 is formed on the copper foil, and the copper foil is then partially etched to form the dummy pattern 31. The first insulating layer 32a and the second insulating layer 32b are overlapped so that the wiring pattern 30 and the dummy pattern 31 face each other, and the dummy pattern 31 is inserted into the gap between the wiring pattern 30. The heater 3 is manufactured by bonding the first insulating layer 32a and the second insulating layer 32b together. Through holes 36h, 37h, and 38h formed in the first insulating layer 32a and the second insulating layer 32b may be used to align the wiring pattern 30 and the dummy pattern 31. For example, by passing an alignment pin through one of the through holes 36h, 37h, and 38h, the wiring pattern 30 and the dummy pattern 31 can be properly aligned so that they do not overlap.

[0062] Alternatively, for example, when dummy pattern 31 is formed from resin, a resin sheet is cut into the shape of dummy pattern 31. Dummy portion 31d made of the cut resin sheet is placed on the polyimide film that will become second insulating layer 32b on which wiring pattern 30 is formed, so as not to overlap wiring pattern 30. A polyimide film that will become first insulating layer 32a is placed on top of wiring pattern 30 and dummy pattern 31, and first insulating layer 32a and second insulating layer 32b are bonded together.

[0063] <Total area ratio of wiring patterns and dummy patterns> The ratio of the total area of ​​the wiring pattern 30 and the dummy pattern 31 to the effective area of ​​the insulating layer 32 is 60% or more. The higher the ratio of the total area, the less likely recesses are to be formed on both sides of the heater 3. When the ratio of the total area is 60% or more, both sides of the heater 3 can be flattened, and the flatness of the surface of the heater 3 can be increased. The flatness of the surface of the heater 3 can be, for example, 20 μm or less. Furthermore, when the dummy pattern 31 is made of metal, the higher the ratio of the total area, the more improved the thermal conductivity of the heater 3. The ratio of the total area may be 65% or more, or even 70% or more. The ratio of the total area is, for example, 90% or less or 80% or less.

[0064] The area of ​​the wiring pattern 30 is the area of ​​the wiring pattern 30 in a planar view. The area of ​​the dummy pattern 31 is the area of ​​the dummy pattern 31 in a planar view. The effective area of ​​the insulating layer 32 is the maximum area in which the wiring pattern 30 can be arranged on the insulating layer 32. In FIG. 6, the effective area of ​​the insulating layer 32 is surrounded by a two-dot chain line and indicated by hatching. The "effective area of ​​the insulating layer" is the area of ​​the insulating layer 32 in a planar view, excluding portions where the wiring pattern 30 cannot be arranged. The portions where the wiring pattern 30 cannot be arranged are portions that interfere with other components and portions necessary for insulation. Examples of other components include the fastening member 6, the support post 71, and the terminals of the power line (not shown) shown in FIG. 1. The portions where the wiring pattern 30 cannot be arranged are, for example, the vicinity of the through holes 36h, 37h, and 38h, and the vicinity of the outer periphery of the insulating layer 32. For example, the area within 2 mm from the opening edge of each through-hole and the area within 2 mm from the outer periphery of the insulating layer 32 are defined as areas where the wiring pattern 30 cannot be disposed.

[0065] The area of ​​the wiring pattern 30 varies depending on the specifications of the wiring pattern 30, but is generally 20% to 40% of the effective area of ​​the insulating layer 32.

[0066] <Maximum length of dummy part> The maximum length L of each of the dummy portions 31d shown in FIGS. 5 and 7 satisfies the relationship of the following formula (1). Formula (1) L≦40 / ((xy)×ΔT) x is the linear expansion coefficient of the material of the dummy pattern 31 . y is the linear expansion coefficient of the material of the insulating layer 32; ΔT is the operating temperature range of the heater 3.

[0067] As shown in FIG. 5, the "maximum length L of the dummy portion" is the longest distance between two points on the outline of the dummy portion 31d in a plan view of the dummy pattern 31. The linear expansion coefficient x of the dummy pattern 31 and the linear expansion coefficient y of the insulating layer 32 are each the average linear expansion coefficient in the operating temperature range of the heater 3. The unit of the linear expansion coefficient is " / K". For example, if the operating temperature range ΔT is from 25°C to 200°C, it is 175°C.

[0068] When the wiring pattern 30 generates heat during use of the heater 3, the temperatures of the dummy pattern 31 and the insulating layer 32 rise. The amount of thermal expansion of the dummy portion 31d is expressed as x × ΔT × L. The amount of thermal expansion of the insulating layer 32 on the dummy portion 31d is expressed as y × ΔT × L. The difference between the amount of thermal expansion of the dummy portion 31d and the amount of thermal expansion of the insulating layer 32 causes the insulating layer 32 on the dummy portion 31d to deform. The insulating layer 32 bonded to the dummy portion 31d is substantially restrained from extending beyond the contour of the dummy portion 31d. Therefore, the thermally expanded insulating layer 32 is pulled toward the inside of the contour of the dummy portion 31d, deforming so as to rise above the surface of the dummy portion 31d. In this case, the height of wrinkles that occur on the surface of the heater 3 due to the deformation of the insulating layer 32 is half the difference in the amount of thermal expansion. For example, if the difference in thermal expansion between the dummy portion 31d and the insulating layer 32 is 40 μm, the wrinkle height will be 20 μm. Therefore, to keep the wrinkle height at 20 μm or less, the difference in thermal expansion should be 40 μm or less. If the maximum length L of the dummy portion 31d satisfies the above formula (1), the wrinkle height can be reduced to 20 μm or less. The flatness of the surface of the heater 3 can be maintained at 20 μm or less. The flatness is measured in accordance with JIS B0621-1984.

[0069] The maximum length L of the dummy portion 31d is, for example, 50 mm or less. By setting the maximum length L to 50 mm or less, it is possible to reduce the height of wrinkles that occur due to the difference in the amount of thermal expansion between the dummy portion 31d and the insulating layer 32. This makes it easier to maintain the flatness of the surface of the heater 3. The maximum length L may be 45 mm or less, or even 40 mm or less.

[0070] <Distance between wiring pattern and dummy pattern> When the material of the dummy pattern 31 is metal, the distance D1 between the wiring pattern 30 and the dummy pattern 31 shown in FIG. 2 is, for example, 1 mm or more. Specifically, the distance D1 is the distance between the wiring pattern 30 and the dummy portion 31d adjacent to the wiring pattern 30. The dummy portion 31d adjacent to the wiring pattern 30 is the dummy portion 31d closest to the wiring pattern 30. By setting the distance D1 to 1 mm or more, a sufficient insulating distance can be maintained between the wiring pattern 30 and the dummy pattern 31. Since current can be prevented from flowing from the wiring pattern 30 to the dummy pattern 31, the dummy pattern 31 does not generate heat. The distance D1 is, for example, 20 mm or less, 10 mm or less, or 5 mm or less.

[0071] <Distance between dummy parts> The distance D2 between adjacent dummy portions 31d is, for example, 2 mm or less. If the material of the dummy pattern 31 is metal, the thermal conductivity of the heater 3 can be improved by making the distance D2 2 mm or less. The distance D2 is, for example, 0.2 mm or more, 0.5 mm or more, or 1 mm or more. If the material of the dummy pattern 31 is an insulating material, the distance D2 may be zero.

[0072] As shown in Fig. 3, the dummy portion 31d is preferably located around the through hole 36h. The periphery of the through hole 36h is the region between 2 mm and 5 mm from the edge of the opening of the through hole 36h. The fastening member 6 shown in Fig. 1 is inserted into the through hole 36h. When the heater 3 is fastened by the fastening member 6, the periphery of the through hole 36h is compressed. By having the dummy portion 31d located around the through hole 36h, the periphery of the through hole 36h is less likely to be depressed.

[0073] <First insulation sheet and second insulation sheet> The first insulating sheet 41 and the second insulating sheet 42 shown in FIG. 1 function as cushioning materials to protect the heater 3. The first insulating sheet 41 contacts the upper surface of the heater 3. The second insulating sheet 42 contacts the lower surface of the heater 3. Neither the first insulating sheet 41 nor the second insulating sheet 42 is adhered to the heater 3. The first insulating sheet 41 and the second insulating sheet 42 may be omitted. When the heater 3 is installed on the substrate holder 1 as shown in FIG. 1, the first insulating sheet 41 and the second insulating sheet 42 are compressed while sandwiched between the mounting plate 2 and the support plate 5. As the first insulating sheet 41 and the second insulating sheet 42 are compressed, they are pressed against the heater 3. The first insulating sheet 41 is in close contact with the upper surface of the heater 3. The second insulating sheet 42 is in close contact with the upper surface of the heater 3. Therefore, even if both surfaces of the heater 3 are uneven, gaps are unlikely to occur between the heater 3 and the first insulating sheet 41 and between the heater 3 and the second insulating sheet .

[0074] Since gaps are unlikely to occur between the heater 3 and the first insulating sheet 41, and between the heater 3 and the second insulating sheet 42, heat transfer is unlikely to be hindered. Heat generated in the wiring pattern 30 is transferred to the first insulating sheet 41 and the second insulating sheet 42. The heat transferred to the first insulating sheet 41 is transferred to the mounting plate 2. Since heat transfer is unlikely to be hindered by gaps, heat generated in the wiring pattern 30 is likely to be transferred evenly to the mounting plate 2. This makes it easier to achieve a uniform temperature distribution on the upper surface of the mounting plate 2. In addition, heat generated in the wiring pattern 30 is easily dissipated through the first insulating sheet 41 and the second insulating sheet 42. This reduces excessive temperature rise in the wiring pattern 30, making it less likely that the wiring pattern 30 will become abnormally high in temperature.

[0075] In this example, the first insulating sheet 41 and the second insulating sheet 42 each have a rectangular planar shape. The size of each of the first insulating sheet 41 and the second insulating sheet 42 is equal to the size of the heater 3. The first insulating sheet 41 and the second insulating sheet 42 each have a through hole through which the fastening member 6 shown in FIG. 1 is inserted. The first insulating sheet 41 and the second insulating sheet 42 also have a through hole through which the support post 71 shown in FIG. 1 is inserted. With the heater 3 sandwiched between the first insulating sheet 41 and the second insulating sheet 42, the fastening member 6 is inserted into each through hole. This prevents the first insulating sheet 41 and the second insulating sheet 42 from shifting in position even if the first insulating sheet 41 and the second insulating sheet 42 are not bonded to the heater 3.

[0076] 〔material〕 The first insulating sheet 41 and the second insulating sheet 42 are formed of an insulating resin that has excellent heat resistance, elasticity, and thermal conductivity. The heat resistance temperature of each of the first insulating sheet 41 and the second insulating sheet 42 is, for example, 200°C or higher. If the heat resistance temperature of each of the first insulating sheet 41 and the second insulating sheet 42 is 200°C or higher, the first insulating sheet 41 and the second insulating sheet 42 are less likely to be damaged by heat generated in the wiring pattern 30. The heat resistance temperature of each of the first insulating sheet 41 and the second insulating sheet 42 may be 210°C or higher. The elasticity of the first insulating sheet 41 and the second insulating sheet 42 makes it easy for them to adhere to both sides of the heater 3. The thermal conductivity of the first insulating sheet 41 and the second insulating sheet 42 makes it easy for them to transfer heat generated in the wiring pattern 30.

[0077] The material of each of the first insulating sheet 41 and the second insulating sheet 42 is, for example, silicone resin filled with a filler, and the filler is, for example, a ceramic filler. The filler is, for example, granular or fibrous. The ceramic filler material is, for example, boron nitride, aluminum nitride, aluminum oxide, or silicon oxide. Silicone resin filled with a filler can improve thermal conductivity compared to silicone resin alone. Furthermore, a reinforcing material such as glass cloth may be embedded in the first insulating sheet 41 and the second insulating sheet 42. In this example, the first insulating sheet 41 and the second insulating sheet 42 are formed from silicone resin filled with a filler. Glass cloth is embedded in the first insulating sheet 41 and the second insulating sheet 42 as a reinforcing material.

[0078] [Thickness] The thickness of each of the first insulating sheet 41 and the second insulating sheet 42 is greater than half the thickness of the wiring pattern 30. The thickness of each of the first insulating sheet 41 and the second insulating sheet 42 is the thickness in a natural state. The natural state refers to a state in which no external force is applied and no compression is occurring. When the thickness of each of the first insulating sheet 41 and the second insulating sheet 42 is greater than half the thickness of the wiring pattern 30, even if both surfaces of the heater 3 are uneven, voids are less likely to occur between the heater 3 and the first insulating sheet 41 and between the heater 3 and the second insulating sheet 42. The thickness of each of the first insulating sheet 41 and the second insulating sheet 42 may be greater than the thickness of the wiring pattern 30. The greater the thickness of each of the first insulating sheet 41 and the second insulating sheet 42, the more easily the first insulating sheet 41 and the second insulating sheet 42 can fill the unevenness on both surfaces of the heater 3, making voids less likely to occur. In addition, the surfaces of the first insulating sheet 41 and the second insulating sheet 42 are more likely to be maintained flat.

[0079] The thicker the first insulating sheet 41 and the second insulating sheet 42, the greater their thermal resistance. Therefore, heat transfer through the first insulating sheet 41 and the second insulating sheet 42 is slower. The upper limit of the thickness of each of the first insulating sheet 41 and the second insulating sheet 42 is, for example, 1.0 mm. A thickness of 1.0 mm or less allows heat generated in the wiring pattern 30 to be easily dissipated through the first insulating sheet 41 and the second insulating sheet 42. This reduces excessive temperature rise in the wiring pattern 30 and prevents the wiring pattern 30 from becoming abnormally hot. Furthermore, a thickness of 1.0 mm or less allows the first insulating sheet 41 and the second insulating sheet 42 to be installed in a limited space on the substrate holder 1. A specific thickness is, for example, 0.1 mm to 1.0 mm, or even 0.2 mm to 0.8 mm. In this example, the thickness of each of the first insulating sheet 41 and the second insulating sheet 42 is 0.5 mm.

[0080] [Hardness] The hardness of each of the first insulating sheet 41 and the second insulating sheet 42 is less than the hardness of the insulating layer 32. In other words, each of the first insulating sheet 41 and the second insulating sheet 42 is softer than the insulating layer 32. Because the hardness of each of the first insulating sheet 41 and the second insulating sheet 42 is less than the hardness of the insulating layer 32, the first insulating sheet 41 and the second insulating sheet 42 are more likely to deform to fill in the irregularities on both sides of the heater 3. This makes it less likely that gaps will form between the heater 3 and the first insulating sheet 41, and between the heater 3 and the second insulating sheet 42.

[0081] The specific hardness of each of the first insulating sheet 41 and the second insulating sheet 42 is, for example, 10 or more and 90 or less in durometer A. If the hardness of each of the first insulating sheet 41 and the second insulating sheet 42 is 90 or less in durometer A, the first insulating sheet 41 and the second insulating sheet 42 are easily deformed, and it is possible to prevent gaps from occurring between the heater 3 and the first insulating sheet 41 and between the heater 3 and the second insulating sheet 42. The hardness of each of the first insulating sheet 41 and the second insulating sheet 42 may be 60 or more and 90 or less in durometer A, or even 80 or more and 90 or less. In this example, the hardness of each of the first insulating sheet 41 and the second insulating sheet 42 is 88 or more and 90 or less in durometer A.

[0082] [Thermal conductivity] The thermal conductivity of each of the first insulating sheet 41 and the second insulating sheet 42 is, for example, 3.0 W / m·K or more. The thermal conductivity of each of the first insulating sheet 41 and the second insulating sheet 42 is the thermal conductivity in the direction along the thickness of each of the first insulating sheet 41 and the second insulating sheet 42. This thermal conductivity is a value at 20°C. When the thermal conductivity of each of the first insulating sheet 41 and the second insulating sheet 42 is 3.0 W / m·K or more, heat is easily transmitted through the first insulating sheet 41 and the second insulating sheet 42. This facilitates dissipation of heat generated in the wiring pattern 30. This reduces excessive temperature rise in the wiring pattern 30 and makes it less likely for the wiring pattern 30 to become abnormally hot. The thermal conductivity of each of the first insulating sheet 41 and the second insulating sheet 42 may be 4.0 W / m·K or more, or even 5.0 W / m·K or more.

[0083] ≪Support plate≫ As shown in FIG. 1, the support plate 5 is a member that supports the heater 3 between itself and the mounting plate 2. In this example, the support plate 5 is disposed below the mounting plate 2, more specifically below the second insulating sheet 42. The support plate 5 is formed of a material that is more rigid than the heater 3. The material of the support plate 5 is, for example, a metal, a ceramic, or a composite containing ceramic. The material of the support plate 5 can be any of the materials listed as the materials for the mounting plate 2, or stainless steel or Kovar.

[0084] The support plate 5 is formed with through holes through which the fastening members 6 shown in Fig. 1 are inserted. The support plate 5 is also formed with through holes through which the support posts 71 shown in Fig. 1 are inserted.

[0085] <Fastening components> The fastening member 6 fastens the mounting plate 2, heater 3, and support plate 5 together. The fastening member 6 secures the heater 3 and support plate 5 to the mounting plate 2. As shown in FIG. 1 , the fastening member 6 is inserted from below the support plate 5 and connected to the underside 21 of the mounting plate 2. The fastening member 6 is, for example, a bolt. The underside 21 has an internal thread to which an external thread formed at the tip of the bolt is connected. The fastening member 6 in this example has a length that penetrates the first insulating sheet 41, heater 3, second insulating sheet 42, and support plate 5. When the heater 3 is sandwiched between the mounting plate 2 and the support plate 5 and tightened by the fastening member 6, the first insulating sheet 41 and the second insulating sheet 42 are compressed. The fastening member 6 in this example is a bolt.

[0086] <Pedestal> The base 7 is a member that supports the substrate holder 1. The material of the base 7 is, for example, metal, ceramic, or a composite containing ceramic. The materials listed as the materials for the mounting plate 2 can be used as the material of the base 7.

[0087] The pedestal 7 in this example has a support pillar 71 extending upward from the upper surface of the pedestal 7. The support pillar 71 supports the substrate holder 1 so that a space is formed between the substrate holder 1 and the pedestal 7. The support pillar 71 in this example penetrates the heater 3 and the support plate 5, and has a length that reaches from the upper surface of the pedestal 7 to the lower surface 21 of the mounting plate 2. The support pillar 71 is cylindrical.

[0088] [Embodiment 2] The configuration of a substrate holder 1 of embodiment 2 will be described with reference to FIG. 8. The substrate holder 1 of embodiment 2 differs from the substrate holder 1 of embodiment 1 shown in FIG. 1 in that it includes a cooling plate 8. The cooling plate 8 is disposed between the mounting plate 2 and the heater 3. Embodiment 2 does not include the first insulating sheet 41 and second insulating sheet 42 shown in FIG. 1. The substrate holder 1 of embodiment 2 includes, from top to bottom, the mounting plate 2, the cooling plate 8, the heater 3, and the support plate 5. The fastening member 6 penetrates the cooling plate 8, the heater 3, and the support plate 5, and is connected to the underside 21 of the mounting plate 2. The cooling plate 8 and the mounting plate 2 may be insulated from each other by an insulator (not shown). As in embodiment 1, the first insulating sheet 41 and the second insulating sheet 42 may be disposed on both sides of the heater 3.

[0089] ≪Cooling plate≫ The cooling plate 8 is used, for example, to cool the substrate 100 heated by the heater 3. The cooling plate 8 cools the substrate 100 by cooling the mounting plate 2. The cooling plate 8 of this example has a flow path 80 for flowing a coolant inside the cooling plate 8. The cooling plate 8 is provided with a supply port 81 for supplying the coolant to the flow path 80 and an outlet 82 for discharging the coolant from the flow path 80. Although not shown here, the supply port 81 and the outlet 82 are each connected to a tank that stores the coolant by piping. The coolant is pumped from the tank to the supply port 81 by a pump. The coolant is returned to the tank from the outlet 82. The coolant flowing through the flow path 80 cools the cooling plate 8 and thus the mounting plate 2. After the substrate 100 is heated, the cooling plate 8 cools the mounting plate 2, thereby quickly cooling the substrate 100. The cooling plate 8 is made of a material such as a metal, ceramic, or a composite containing ceramics. The cooling plate 8 can be made of the same material as that of the mounting plate 2 .

[0090] In the substrate holder 1 shown in FIG. 8, the cooling plate 8 is disposed on the lower surface 21 of the mounting plate 2 , but the cooling plate 8 may also be disposed on the lower surface of the support plate 5 .

[0091] [Test Example 1] A heater was manufactured in which a wiring pattern and a dummy pattern were sandwiched between a first insulating layer and a second insulating layer, and the flatness of the heater surface was examined.

[0092] The wiring pattern and dummy pattern are made of the same metal foil. The metal foil is stainless steel foil. The thickness of the metal foil is 0.05 mm. The first insulating layer and the second insulating layer are made of polyimide film. The thickness of the polyimide film is 0.05 mm.

[0093] The ratio of the area of ​​the wiring pattern to the effective area of ​​the insulating layer is 32%. The ratio of the area of ​​the dummy pattern to the effective area of ​​the insulating layer is 35%. The ratio of the total area of ​​the wiring pattern and the area of ​​the dummy pattern 31 is 67% or more.

[0094] <Sample No. 1> For heater sample No. 1, the dummy pattern was divided into multiple dummy sections so that the maximum length L of each dummy section was 50 mm or less. The distance D1 between the wiring pattern and the dummy section adjacent to the wiring pattern was 1 mm or more and 2 mm or less. The distance D2 between adjacent dummy sections was 1 mm.

[0095] <Sample No. 2> The heater of sample No. 2 differs from the heater of sample No. 1 in that the dummy pattern is not divided. In sample No. 2, the maximum length L of the dummy pattern is 100 mm or more.

[0096] The flatness of the heater surface was measured before use, and the flatness of the heaters of Samples No. 1 and No. 2 was 8 μm.

[0097] A heater was set on a substrate holder with the structure shown in Figure 1, and a test was conducted in which the heater was heated and cooled 500 times. The operating temperature range ΔT of the heater was 25°C to 200°C. After the test, the heater was removed from the substrate holder. The flatness of the heater surface after use was measured. The flatness of the heater surface of sample No. 1 was maintained at 10 μm or less. In contrast, wrinkles had appeared on the heater surface of sample No. 2, and the flatness of the heater surface was over 20 μm. [Explanation of symbols]

[0098] 1 Board holder 2. Mounting plate 20 top, 21 bottom 3 Heater 30 wiring patterns, 30t terminals 31 dummy pattern, 31d dummy part 32 Insulating layer 32a: first insulating layer; 32b: second insulating layer 36h, 37h, 38h through hole 41 First insulating sheet 42 Second insulating sheet 5 Support plate 6 Fastening members 7. Pedestal 71 Pillar 8 cooling plate, 80 flow path, 81 supply port, 82 discharge port 100 boards D1, D2 distance L Maximum length

Claims

1. a mounting plate having an upper surface on which a substrate is placed, a sheet-like heater, and a support plate, in this order; The heater is a wiring pattern that forms a heat generating circuit; a dummy pattern separated from the wiring pattern in the same plane as the wiring pattern; an insulating layer that covers the wiring pattern and the dummy pattern, the dummy pattern has a plurality of dummy portions arranged apart from each other, a material of the dummy pattern is different from a material of the insulating layer; When the heater is viewed from the top, the ratio of the total area of ​​the wiring pattern and the dummy pattern to the effective area of ​​the insulating layer is 60% or more; a maximum length L of each of the dummy portions satisfies L≦40 / ((x−y)×ΔT), x is the linear expansion coefficient of the material of the dummy pattern, y is the linear expansion coefficient of the material of the insulating layer, ΔT is the operating temperature range of the heater; Substrate holder.

2. 2. The substrate holder according to claim 1, wherein the material of the dummy patterns is metal.

3. 3. The substrate holder according to claim 1, wherein the material of said dummy pattern is the same as the material of said wiring pattern.

4. 3. The substrate holder according to claim 1, wherein the maximum length L is 50 mm or less.

5. 3. The substrate holder according to claim 1, wherein the distance between adjacent dummy portions is 2 mm or less.

6. 3. The substrate holder according to claim 1, wherein the distance between the wiring pattern and the dummy portion adjacent to the wiring pattern is 1 mm or more.

7. 3. The substrate holder according to claim 1, wherein the insulating layer is made of polyimide.

Images