Infrared heater

Abstract

Provided is an infrared heater having excellent heat resistance. An infrared heater according to one embodiment of the present invention comprises: a dielectric layer; a conductor pattern including a plurality of first conductor parts; and a second conductor part. The conductor pattern is disposed on the dielectric layer. The plurality of first conductor parts are arranged spaced apart from each other so as to constitute a periodic structure. The second conductor part is disposed on the opposite side to the conductor pattern with respect to the dielectric layer. Each of the plurality of first conductor parts includes a first adhesive layer, a first barrier layer, and a first body layer. The first adhesive layer is in contact with the dielectric layer. The first body layer is disposed on the opposite side to the dielectric layer with respect to the first adhesive layer. The first barrier layer is disposed between the first adhesive layer and the first body layer. The first barrier layer can barrier transition of a material constituting the first adhesive layer to the first body layer.

Description

Infrared heater

[0001] The present invention relates to an infrared heater.

[0002] Infrared heaters that emit infrared rays have been known. Such infrared heaters are desired to emit narrow-band infrared rays in order to efficiently transfer energy to an object. For example, an infrared heater has been proposed that includes a heating element and a structure having an infrared radiation surface, the structure including a first conductor layer including a plurality of individual conductor layers forming a periodic structure, an adhesive layer, a dielectric layer, and a second conductor layer, in that order (see, for example, Patent Document 1). In such an infrared heater, when the structure absorbs energy from the heating element, infrared rays are emitted having a maximum peak with a half-width of 1.5 μm or less and an emissivity of 0.8 or more. In recent years, there has been a demand for improving the radiant energy intensity of infrared rays emitted from infrared heaters. Therefore, in the infrared heater described in Patent Document 1, efforts have been made to heat the structure to higher temperatures (e.g., 400°C or higher) to improve the radiant energy intensity of infrared rays. Therefore, improvements in the heat resistance of infrared heaters are desired so that they can operate in high-temperature ranges.

[0003] Japanese Patent Application Laid-Open No. 2017-50254

[0004] A primary object of the present invention is to provide an infrared heater having excellent heat resistance.

[0005] [1] An infrared heater according to one embodiment of the present invention includes a dielectric layer, a conductor pattern including a plurality of first conductor portions, and a second conductor portion. The conductor pattern is disposed on the dielectric layer. The plurality of first conductor portions are arranged at intervals to form a periodic structure. The second conductor portion is disposed on the opposite side of the dielectric layer from the conductor pattern. Each of the plurality of first conductor portions includes a first adhesive layer, a first barrier layer, and a first main layer. The first adhesive layer is in contact with the dielectric layer. The first main layer is disposed on the opposite side of the first adhesive layer from the dielectric layer. The first barrier layer is disposed between the first adhesive layer and the first main layer. The first barrier layer can prevent migration of a material constituting the first adhesive layer into the first main layer. [2] In the infrared heater described in [1] above, the thickness of the first barrier layer may be 0.2 nm or more and 50 nm or less. [3] In the infrared heater described in [1] or [2] above, the material constituting the first barrier layer may contain a platinum group element and / or an oxide thereof. [4] In the infrared heater described in any of [1] to [3] above, the second conductor may include a second adhesive layer, a second barrier layer, and a second main layer. The second adhesive layer is in contact with the dielectric layer. The second main layer is disposed on the opposite side of the second adhesive layer from the dielectric layer. The second barrier layer is disposed between the second adhesive layer and the second main layer. The second barrier layer can prevent migration of the material constituting the second adhesive layer to the second main layer. [5] The infrared heater described in [4] above may further include a support substrate. The support substrate is disposed on the opposite side of the second conductor from the dielectric layer. [6] In the infrared heater described in [5] above, the second conductor may further include a third adhesive layer and a third barrier layer. The third adhesive layer is in contact with the support substrate. The third barrier layer is disposed between the third adhesive layer and the second body layer. The third barrier layer is capable of preventing migration of materials constituting the third adhesive layer into the second body layer.[7] In the infrared heater according to any one of [1] to [6] above, the thickness of each of the plurality of first conductors may be 30 nm or more and 200 nm or less. When each of the plurality of first conductors has a rectangular shape when viewed in the thickness direction, the length of one side of the first conductor may be 500 nm or more and 8000 nm or less. When each of the plurality of first conductors has a circular shape when viewed in the thickness direction, the diameter of the first conductor may be 500 nm or more and 8000 nm or less. [8] In the infrared heater according to any one of [1] to [7] above, the spacing between adjacent first conductors among the plurality of first conductors may be 300 nm or more and 4000 nm or less. [9] The infrared heater according to any one of [1] to [8] above may further include a heating unit. The heating unit is capable of heating a metamaterial structure composed of the dielectric layer, the plurality of first conductors, and the second conductor.

[10] In the infrared heater according to [9] above, the metamaterial structure may be configured such that a resonance phenomenon due to magnetic polaritons occurs when the heating unit is heated. The infrared heater may be capable of emitting infrared light having a maximum peak with a normal emissivity of 0.8 or more. The peak wavelength of the maximum peak may be 2 μm or more and 10 μm or less, and the half-width of the maximum peak may be 1.5 μm or less.

[0006] According to the embodiment of the present invention, an infrared heater having excellent heat resistance can be realized.

[0007] FIG. 1 is a schematic cross-sectional view of an infrared heater according to one embodiment of the present invention. FIG. 2 is a II-II' cross-sectional view of a first conductor in FIG. 1. FIG. 3A is a schematic cross-sectional view illustrating a step of preparing a support substrate in a method of manufacturing an infrared heater according to one embodiment of the present invention. FIG. 3B is a schematic cross-sectional view illustrating a step of forming a second conductor on the support substrate in FIG. 3A. FIG. 3C is a schematic cross-sectional view illustrating a step of forming a dielectric layer on the second conductor in FIG. 3B. FIG. 3D is a schematic cross-sectional view illustrating a step of forming a resist pattern on the dielectric layer in FIG. 3C. FIG. 3E is a schematic cross-sectional view illustrating a step of forming a conductor pattern on the dielectric layer via the resist pattern in FIG. 3D. FIG. 4 is a graph showing infrared emissivity curves before and after a heating endurance test for the infrared heater of Example 2. FIG. 5 is a graph showing infrared emissivity curves before and after a heating endurance test for the infrared heater of Comparative Example 2. FIG. 6 is a graph showing infrared emissivity curves before and after a heating endurance test for the infrared heater of Example 2. FIG. 7 is a graph showing infrared emissivity curves before and after a heating endurance test for the infrared heater of Example 3. Fig. 8 is a graph showing infrared emissivity curves before and after a heating durability test for the infrared heater of Example 4. Fig. 9 is a scanning electron microscope (SEM) photograph of the first conductor of the infrared heater of Example 2 before the heating durability test. Fig. 10 is an SEM photograph of the first conductor of the infrared heater of Example 2 after a 500-hour heating durability test. Fig. 11 is an SEM photograph of the first conductor of the infrared heater of Example 3 after a 500-hour heating durability test. Fig. 12 is an SEM photograph of the first conductor of the infrared heater of Example 4 after a 500-hour heating durability test.

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In addition, in order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part more schematically than in the embodiment, but these are merely examples and do not limit the interpretation of the present invention.

[0009] A. Overview of Infrared Heater Fig. 1 is a schematic cross-sectional view of an infrared heater according to one embodiment of the present invention, and Fig. 2 is a cross-sectional view of the first conductor portion taken along line II-II' in Fig. 1. Note that hatching has been omitted in Fig. 2 for the sake of convenience.

[0010] The illustrated infrared heater 100 is capable of emitting infrared rays with a controlled wavelength, more specifically, infrared rays with a controlled wavelength (hereinafter referred to as the peak wavelength) at which the normal emissivity is maximized. In other words, the infrared heater 100 typically functions as a wavelength-controlled heater. As shown in FIG. 1 , the infrared heater 100 includes a dielectric layer 1, a conductor pattern 4 including a plurality of first conductor portions 41, and a second conductor portion 2. The conductor pattern 4 is disposed on the dielectric layer 1. The plurality of first conductor portions 41 are arranged at intervals to form a periodic structure. The second conductor portion 2 is disposed on the opposite side of the dielectric layer 1 from the conductor pattern 4. Each of the plurality of first conductor portions 41 includes a first adhesive layer 41a, a first barrier layer 41b, and a first main layer 41c. The first adhesive layer 41a is in contact with the dielectric layer 1. The first main layer 41c is disposed on the opposite side of the first adhesive layer 41a from the dielectric layer 1. The first barrier layer 41b is disposed between the first adhesive layer 41a and the first main layer 41c. The first barrier layer 41b prevents the material constituting the first adhesive layer 41a from migrating to the first main layer 41c. The inventors discovered that when an infrared heater is operated in a high temperature range (e.g., 400°C or higher), the maximum emissivity of the infrared radiation emitted by the infrared heater gradually decreases. Therefore, after extensive research into improving the heat resistance of the infrared heater, they found that providing a first barrier layer between the first adhesive layer and the first main layer in the first conductor can sufficiently improve the heat resistance of the infrared heater. More specifically, providing a first barrier layer between the first adhesive layer and the first main layer can prevent the material constituting the first adhesive layer from migrating to the first main layer. This prevents the material of the first adhesive layer from migrating to the first main layer and forming an oxide film on the first main layer, even when the infrared heater is operated in a high temperature range. Therefore, the infrared heater 100 can operate in a high temperature range for a long period of time and can stably emit infrared rays with an excellent maximum normal emissivity. Such an infrared heater 100 can operate suitably in a temperature range of, for example, 10°C to 600°C, for example, 650°C to 800°C, or for example, 400°C to 1000°C.

[0011] In the illustrated example, the plurality of first conductors 41, the dielectric layer 1, and the second conductors 2 constitute a metamaterial structure 10. The metamaterial structure 10 is typically configured to generate a resonance phenomenon due to magnetic polaritons. When this resonance phenomenon occurs, a strong electromagnetic field confinement effect can occur within the dielectric layer 1 between the plurality of first conductors 41 and the second conductors 2. This causes the portions of the dielectric layer 1 sandwiched between the first conductors 41 and the second conductors 2 to function as an infrared radiation source. Then, infrared rays with a controlled peak wavelength are radiated from a portion of the surface of the dielectric layer 1 where the plurality of first conductors 41 are not provided (hereinafter referred to as the radiation surface 1a), after going around the plurality of first conductors 41.

[0012] In one embodiment, the infrared heater 100 is capable of emitting infrared rays having a maximum peak normal emissivity of 0.80 or greater. The maximum peak can be determined, for example, from an infrared emissivity curve (see FIG. 4 ) obtained by plotting the wavelength of the infrared rays versus the normal emissivity. The peak wavelength of the maximum peak is, for example, in the range of 2.0 μm to 10 μm, and for example, in the range of 3.0 μm to 7.0 μm. The normal emissivity of the maximum peak is preferably 0.85 or greater, more preferably 0.90 or greater. On the other hand, the upper limit of the normal emissivity of the maximum peak is typically 1.0. The normal emissivity of infrared rays is calculated, for example, by applying Kirchhoff's law with transmittance set to 0, using the following formula (1). The normal reflectance is measured, for example, using a Fourier transform infrared spectrometer (FT-IR) equipped with an integrating sphere. (Normal emissivity) = 1 - (Normal reflectivity) (1) The half-width of the maximum peak is, for example, 1.5 μm or less, and preferably 1.0 μm or less. On the other hand, the lower limit of the half-width of the maximum peak is typically 0 μm. In the above-mentioned infrared emissivity curve, it is preferable that no peaks with normal emissivity of 0.2 or more exist in wavelength regions other than the wavelength region from the rise to the fall of the maximum peak.

[0013] In one embodiment, the second conductor 2 includes a second adhesive layer 2a, a second barrier layer 2b, and a second main layer 2c. The second adhesive layer 2a is in contact with the dielectric layer 1. The second main layer 2c is disposed on the opposite side of the second adhesive layer 2a from the dielectric layer 1. The second barrier layer 2b is disposed between the second adhesive layer 2a and the second main layer 2c. The second barrier layer 2b can prevent the material constituting the second adhesive layer 2a from migrating to the second main layer 2c. With this configuration, the first conductor and the second conductor both have a laminated structure, which allows the above-described resonance phenomenon to occur stably in the metamaterial structure. Furthermore, even when the infrared heater is operated in a high temperature range, the second barrier layer can suppress the material constituting the second adhesive layer from migrating to the second main layer. This can further improve the heat resistance of the infrared heater and more stably radiate infrared rays having the above-described maximum peak.

[0014] In one embodiment, the infrared heater 100 further includes a support substrate 5. The support substrate 5 is disposed on the opposite side of the second conductor portion 2 from the dielectric layer 1. This allows the support substrate to stably support the metamaterial structure described above.

[0015] In one embodiment, the second conductor 2 further includes a third adhesive layer 3a and a third barrier layer 3b. The third adhesive layer 3a is in contact with the support substrate 5. The third barrier layer 3b is disposed between the third adhesive layer 3a and the second main layer 2c. The third barrier layer 3b can prevent the material constituting the third adhesive layer 3a from migrating to the second main layer 2c. This configuration ensures sufficient adhesion of the second conductor to the support substrate, and the third barrier layer can suppress the material constituting the third adhesive layer from migrating to the second main layer even when the infrared heater is operated in a high temperature range. This further improves the heat resistance of the infrared heater, enabling it to more stably emit infrared rays having the above-mentioned maximum peak.

[0016] In one embodiment, the infrared heater 100 further includes a heating unit 6. The heating unit 6 is capable of heating the metamaterial structure 10. In the metamaterial structure 10, the above-described resonance phenomenon can occur due to heating by the heating unit 6. This allows the infrared heater to stably emit the above-described infrared rays. In the illustrated example, the heating unit 6 is disposed on the opposite side of the support substrate 5 from the second conductor 2. Therefore, the heating unit can smoothly heat the metamaterial structure via the support substrate.

[0017] The infrared heater 100 has any appropriate shape when viewed in the thickness direction of the dielectric layer 1. Examples of the shape of the infrared heater when viewed in the thickness direction include a triangle, a rectangle, a pentagon, a polygon having hexagons or more, a circle, and an ellipse.

[0018] The following describes the details of each component of the infrared heater.

[0019] B. Dielectric Layer The dielectric layer 1 is disposed between the conductor pattern 4 including a plurality of first conductor portions 41 and the second conductor portion 2. In the illustrated example, the dielectric layer 1 is in direct contact with each of the first conductor portion 41 and the second conductor portion 2.

[0020] The material constituting the dielectric layer 1 may be any suitable inorganic oxide capable of forming a metamaterial structure. Examples of inorganic oxides include silica (SiO ２ ), alumina (Al ２ O ３ ) and preferably alumina. The inorganic oxides can be used alone or in combination.

[0021] The thickness d of the dielectric layer 1 is, for example, 30 nm or more, preferably 100 nm or more, and more preferably 150 nm or more. On the other hand, the thickness d of the dielectric layer 1 is, for example, 300 nm or less, preferably 250 nm or less, and more preferably 210 nm or less. When the thickness of the dielectric layer is in this range, the peak wavelength of the infrared light can be stably adjusted to the above range.

[0022] C. Conductive Pattern Including Multiple First Conductive Portions The conductor pattern 4 is typically provided directly on the surface of the dielectric layer 1 opposite to the second conductor portion 2. The conductor pattern 4 has any appropriate pattern shape that can form a metamaterial structure. As described above, the conductor pattern 4 includes multiple first conductor portions 41. Each of the multiple first conductor portions 41 typically has electrical conductivity.

[0023] The first conductors 41 are arranged at equal intervals on the dielectric layer 1 to form a periodic structure. More specifically, rows of the first conductors 41 arranged at equal intervals in a first plane direction of the dielectric layer 1 are arranged in parallel at equal intervals in a second plane direction perpendicular to the first plane direction (see FIG. 2 ).

[0024] In the surface direction (first surface direction or second surface direction) of the dielectric layer, the spacing between adjacent first conductors 41 among the plurality of first conductors 41 is, for example, 300 nm or more, for example, 500 nm or more, or for example, 1000 nm or more. Meanwhile, the spacing between adjacent first conductors 41 is, for example, 8000 nm or less, for example, 5000 nm or less, or for example, 4000 nm or less. Each of the plurality of first conductors 41 may have any appropriate shape capable of forming a metamaterial structure. Examples of the shape of the first conductors 41 as viewed in the thickness direction include a circle and a rectangle (quadrilateral), preferably a rectangle, and more preferably a square. The dimensions of the first conductors 41 in the surface direction (first surface direction or second surface direction) of the dielectric layer can be arbitrarily and appropriately adjusted according to the desired peak wavelength. When the first conductor portion 41 has a rectangular shape, the side length (width) w of the first conductor portion 41 is, for example, 500 nm or more, or, for example, 1000 nm or more. On the other hand, the side length (width) w of the first conductor portion 41 is, for example, 8000 nm or less, or, for example, 4000 nm or less. When the first conductor portion 41 has a circular shape, the range of the diameter (width) of the first conductor portion 41 is, for example, the same as the range of the width w described above. The shapes and sizes of the multiple first conductor portions 41 may all be the same, or at least some of them may be different. The shapes and sizes of the multiple first conductor portions 41 are preferably all the same. The period Λ of the periodic structure formed by the multiple first conductor portions 41 is the sum of the spacing between adjacent first conductor portions 41 and the width w of the first conductor portion 41. The period Λ can be adjusted arbitrarily and appropriately depending on the desired peak wavelength. The period Λ is, for example, 500 nm or more, or, for example, 1000 nm or more. On the other hand, the period Λ is, for example, 8000 nm or less, or, for example, 4000 nm or less. If the period Λ is in this range, the angle dependency of the infrared heater can be suitably adjusted.

[0025] The thickness h of the first conductor 41 is, for example, 30 nm or more, preferably 50 nm or more. Meanwhile, the thickness h of the first conductor 41 is, for example, 200 nm or less, preferably 150 nm or less, and more preferably 100 nm or less. When the thickness of the first conductor is in this range, the peak wavelength of the infrared light can be stably adjusted within the above range.

[0026] C-1. First Adhesive Layer As described above, each of the multiple first conductors 41 includes a first adhesive layer 41a, a first barrier layer 41b, and a first main body layer 41c. The first adhesive layer 41a typically bonds the first conductor 41 to the dielectric layer 1. This can improve the adhesion of the first conductor to the dielectric layer and can prevent the first conductor from peeling off from the dielectric layer.

[0027] The first adhesive layer 41 a may be made of any suitable metal material, such as chromium (Cr), nickel (Ni), titanium (Ti), or an alloy thereof, preferably titanium (Ti).

[0028] The thickness of the first adhesive layer 41a is, for example, 0.2 nm or more, preferably 3.0 nm or more. If the first adhesive layer has such a thickness, the adhesion of the first conductor portion to the dielectric layer can be stably improved. On the other hand, the thickness of the first adhesive layer 41a is, for example, 30 nm or less, preferably 20 nm or less, more preferably 10 nm or less, and even more preferably 8.0 nm or less.

[0029] C-2. First Barrier Layer In one embodiment, the first barrier layer 41b is provided directly on the surface of the first adhesive layer 41a opposite to the dielectric layer 1. The first barrier layer 41b is typically provided over the entire surface of the first adhesive layer 41a opposite to the dielectric layer 1. This can more stably prevent the material of the first adhesive layer from migrating into the first body layer.

[0030] The first barrier layer 41b may be made of any appropriate metal material. Examples of the metal material constituting the first barrier layer 41b include platinum group elements and their oxides. Specific examples of platinum group elements include platinum (Pt), palladium (Pd), and ruthenium (Ru), preferably platinum (Pt) and palladium (Pd), and more preferably platinum (Pt). The metal material constituting the first barrier layer 41b may also be an alloy of two or more platinum group elements.

[0031] The thickness of the first barrier layer 41b is, for example, 0.2 nm or more, more preferably 1.0 nm or more, and even more preferably 3.0 nm or more. If the first barrier layer has such a thickness, migration of the material of the first adhesive layer to the first main layer can be stably suppressed. On the other hand, the thickness of the first barrier layer 41b is, for example, 50 nm or less, more preferably 30 nm or less, even more preferably 20 nm or less, particularly preferably 15 nm or less, particularly preferably 10 nm or less, and most preferably 8.0 nm or less. If the first barrier layer has such a thickness, the first barrier layer can be prevented from affecting the resonance phenomenon occurring in the metamaterial structure, and infrared rays having the above-mentioned maximum peak can be more stably emitted. Furthermore, if the thickness of the first barrier layer is equal to or less than this upper limit, grain growth in the first barrier layer can be suppressed even when the infrared heater is exposed to high temperatures for a long period of time. Grain growth in the first barrier layer can cause the pattern shape of the first conductor to collapse (deform), which may reduce the maximum emissivity of the infrared rays emitted by the infrared heater. In contrast, in one embodiment, grain growth in the first barrier layer is sufficiently suppressed, so that even if the infrared heater is exposed to high temperatures for a long period of time, the pattern shape of the first conductor can be prevented from collapsing (deforming), and a decrease in the maximum emissivity of infrared rays emitted by the infrared heater can be sufficiently suppressed, thereby further improving the heat resistance of the infrared heater.

[0032] The thickness of the first barrier layer 41b is typically equal to or greater than the thickness of the first adhesive layer 41a. That is, the thickness ratio of the first barrier layer 41b to the thickness of the first adhesive layer 41a (thickness of the first barrier layer / thickness of the first adhesive layer) is, for example, 1.0 or greater. Meanwhile, the ratio (thickness of the first barrier layer / thickness of the first adhesive layer) is, for example, 10 or less, preferably 5.0 or less, and more preferably 2.0 or less. The thickness of the first barrier layer 41b is typically less than the thickness of the first main layer 41c. The thickness ratio of the first barrier layer 41b to the thickness of the first main layer 41c (thickness of the first barrier layer / thickness of the first main layer) is, for example, 0.02 or more, preferably 0.05 or more. Meanwhile, the ratio (thickness of the first barrier layer / thickness of the first main layer) is, for example, 0.50 or less, preferably 0.30 or less, and more preferably 0.15 or less.

[0033] In one embodiment, the first body layer 41c is provided directly on the surface of the first barrier layer 41b opposite to the first adhesive layer 41a. The first body layer 41c is typically provided over the entire surface of the first barrier layer 41b opposite to the first adhesive layer 41a.

[0034] The first body layer 41c may be made of any suitable metal material. Examples of metal materials constituting the first body layer 41c include low-melting-point materials with melting points below 2500°C, high-melting-point materials with melting points of 2500°C or higher, and alloys thereof. Examples of low-melting-point materials include gold (Au, melting point: 1064°C), silver (Ag, melting point: 962°C), copper (Cu, melting point: 1085°C), iron (Fe, melting point: 1538°C), aluminum (Al, melting point: 660°C), and alloys thereof, with gold (Au) being preferred. Examples of high-melting-point materials include iridium (Ir, melting point: 2466°C), ruthenium (Ru, melting point: 2334°C), hafnium nitride (HfN, melting point: 3334°C), titanium nitride (TiN, melting point: 2930°C), and alloys thereof. If the first main body layer contains a high-melting-point material, grain growth in the first main body layer can be suppressed, and therefore, even if the infrared heater is exposed to high temperatures for a long period of time, the pattern shape of the first conductor can be further prevented from collapsing (deforming).

[0035] The thickness of the first main body layer 41c is, for example, 30 nm or more and 200 nm or less, and preferably 50 nm or more and 110 nm or less.

[0036] D. Second Conductor Portion The second conductor portion 2 is typically provided directly on the surface of the dielectric layer 1 opposite the conductor pattern 4. The second conductor portion 2 has electrical conductivity. The second conductor portion 2 may be provided over the entire surface of the dielectric layer 1 opposite the conductor pattern 4, or may be provided over only a portion of that surface. In the illustrated example, the second conductor portion 2 is provided in a layer form over the entire surface of the dielectric layer 1 opposite the conductor pattern 4.

[0037] The second conductor 2 may have a single-layer structure or a layered structure in which multiple metal films are stacked. The second conductor 2 may be made of any suitable metal material capable of forming a metamaterial structure. Examples of suitable metal materials include chromium (Cr), titanium (Ti), ruthenium (Ru), gold (Au), aluminum (Al), nickel (Ni), copper (Cu), silver (Ag), palladium (Pd), and alloys thereof. The thickness f of the second conductor 2 is, for example, 30 nm to 500 nm, preferably 50 nm to 300 nm. When the second conductor has such a thickness, the above-described resonance phenomenon can be stably generated in the metamaterial structure.

[0038] In the illustrated example, the second conductor 2 has a laminated structure and includes a second adhesive layer 2a, a second barrier layer 2b, a second main body layer 2c, a third barrier layer 3b, and a third adhesive layer 3a. The second adhesive layer 2a typically bonds the second conductor 2 to the dielectric layer 1. This can improve the adhesion of the second conductor to the dielectric layer and prevent the second conductor from peeling off from the dielectric layer. The second adhesive layer 2a can be described in the same manner as the first adhesive layer 41a described above. Therefore, a description of the second adhesive layer 2a will be omitted. The metal material constituting the second adhesive layer 2a is preferably the same as the metal material constituting the first adhesive layer 41a. The thickness of the second adhesive layer 2a is preferably the same as the thickness of the first adhesive layer 41a.

[0039] In one embodiment, the second barrier layer 2b is provided directly on the surface of the second adhesive layer 2a opposite to the dielectric layer 1. The second barrier layer 2b is typically provided over the entire surface of the second adhesive layer 2a opposite to the dielectric layer 1. This can more stably suppress migration of the material of the second adhesive layer into the second main layer. The second barrier layer 2b can be described in the same manner as the first barrier layer 41b described above. Therefore, a description of the second barrier layer 2b will be omitted. The metal material constituting the second barrier layer 2b is preferably the same as the metal material constituting the first barrier layer 41b. The thickness of the second barrier layer 2b is preferably the same as the thickness of the first barrier layer 41b.

[0040] In one embodiment, the second body layer 2c is provided directly on the surface of the second barrier layer 2b opposite the second adhesive layer 2a. The second body layer 2c is typically provided over the entire surface of the second barrier layer 2b opposite the second adhesive layer 2a. The second body layer 2c can be described in the same manner as the first body layer 41c described above. Therefore, a description of the second body layer 2c will be omitted. The metal material constituting the second body layer 2c is preferably the same as the metal material constituting the first body layer 41c. The thickness of the second body layer 2c is preferably the same as the thickness of the first body layer 41c.

[0041] In one embodiment, the third adhesive layer 3a is provided directly on the surface of the support substrate 5 facing the second conductor 2. The third adhesive layer 3a may be provided over the entire surface of the support substrate 5 facing the second conductor 2, or may be provided over only a portion of that surface. In the illustrated example, the third adhesive layer 3a is provided over the entire surface of the support substrate 5. The third adhesive layer 3a typically bonds the second conductor 2 to the support substrate 5. This can improve the adhesion of the second conductor to the support substrate and prevent the second conductor from peeling off from the support substrate. The third adhesive layer 3a can be described in the same manner as the first adhesive layer 41a described above. Therefore, a description of the third adhesive layer 3a will be omitted. The metal material constituting the third adhesive layer 3a is preferably the same as the metal material constituting the first adhesive layer 41a. The thickness of the third adhesive layer 3a is preferably the same as the thickness of the first adhesive layer 41a.

[0042] In one embodiment, the third barrier layer 3b is provided directly on the surface of the third adhesive layer 3a opposite the support substrate 5 and is in contact with the second main layer 2c. The third barrier layer 3b is typically provided over the entire surface of the third adhesive layer 3a opposite the support substrate 5. This can more stably suppress migration of the material of the third adhesive layer to the second main layer. The third barrier layer 3b can be described in the same manner as the first barrier layer 41b described above. Therefore, a description of the third barrier layer 3b will be omitted. The metal material constituting the third barrier layer 3b is preferably the same as the metal material constituting the first barrier layer 41b. The thickness of the third barrier layer 3b is preferably the same as the thickness of the first barrier layer 41b.

[0043] E. Support Substrate The support substrate 5 can provide the infrared heater 100 with excellent mechanical strength. Any appropriate substrate that can be used in an infrared heater can be adopted as the support substrate 5. The support substrate 5 typically has a substantially flat plate shape. Examples of materials that constitute the support substrate 5 include materials with excellent heat resistance. Specific examples include sapphire, silicon (Si), and quartz, with quartz being preferred. The support substrate 5 may have a single-layer structure or a layered structure in which multiple substrates are stacked. The thickness of the support substrate 5 is, for example, 100 μm or more and 1000 μm or less, or, for example, 50 μm or more and 700 μm or less.

[0044] F. Heating Unit The heating unit 6 is typically in contact with the surface of the support substrate 5 opposite to the second conductor 2. As described above, the heating unit 6 is capable of heating the metamaterial structure 10. The heating temperature of the heating unit 6 is, for example, 200°C or higher and 800°C or lower, and preferably 650°C or higher and 800°C or lower. The configuration of the heating unit 6 is not particularly limited. Any appropriate heat generating unit can be adopted as the heating unit.

[0045] In one embodiment, the heating unit 6 is configured as a planar heater. In the illustrated example, the heating unit 6 includes a base 62 and a heating element 61. The base 62 is typically made of an insulating material. Examples of insulating materials include insulating resins such as polyimide and insulating ceramic materials. In the illustrated example, the base 62 has a substantially flat plate shape. The heating element 61 is typically embedded in the base 62. In one embodiment, the heating element 61 is a resistive heating element that generates heat when external power is applied. Although not illustrated, the heating element 61 includes heater wiring and terminals. The heater wiring is typically linear or strip-shaped. The heater wiring is routed inside the base 62 in an arbitrary and appropriate manner. Terminals are provided at both ends of the heater wiring. The terminals are typically electrically connected to an external power source. Examples of materials for the heating element 61 include tungsten (W), molybdenum (Mo), tantalum (Ta), Ta, Fe-Cr-Al alloy, and Ni-Cr alloy.

[0046] G. Manufacturing Method of Infrared Heater Next, one embodiment of a manufacturing method of the infrared heater 100 will be described with reference to FIGS. 3A to 3E. First, the support substrate 5 described above is prepared as shown in FIG. 3A. Then, if necessary, the second conductor 2 described above is formed on the support substrate 5 as shown in FIG. 3B. Typically, the second conductor 2 is formed on the support substrate 5. Examples of methods for forming the second conductor 2 include sputtering, plating, and vapor deposition, with sputtering being preferred. In the illustrated example, the second conductor 2 has a second adhesive layer 2a, a second barrier layer 2b, a second main body layer 2c, a third barrier layer 3b, and a third adhesive layer 3a. In this case, the above-described film formation method is repeated to form the third adhesive layer 3a, the third barrier layer 3b, the second main body layer 2c, the second barrier layer 2b, and the second adhesive layer 2a in this order from the support substrate 5 side.

[0047] 3C, the above-described dielectric layer 1 is formed on the second conductor portion 2. Typically, the dielectric layer 1 is formed on the second conductor portion 2. In the illustrated example, the dielectric layer 1 is formed on the second adhesive layer 2a. Examples of methods for forming the dielectric layer 1 include sputtering and atomic layer deposition (ALD).

[0048] Next, as shown in FIGS. 3D and 3E , a conductor pattern 4 including the above-described plurality of first conductors 41 is formed on the dielectric layer 1. In one embodiment, as shown in FIG. 3D , a resist pattern 9 is formed on the dielectric layer 1. Examples of methods for forming the resist pattern 9 include photolithography, nanoimprint lithography, and maskless lithography using electron beam (EB) writing, with photolithography being preferred. This allows openings corresponding to the above-described plurality of first conductors 41 to be formed in the resist pattern 9 with high precision. The size of the openings corresponds to the width w of the above-described first conductors 41. Next, as shown in FIG. 3E , the above-described plurality of first conductors 41 are formed on the portions of the dielectric layer 1 exposed from the resist pattern 9 by any appropriate film formation method. Examples of methods for forming the first conductors 41 include sputtering, plating, and vapor deposition, with vapor deposition being preferred. More specifically, the above-described film formation method is repeated to form the first adhesive layer 41a, the first barrier layer 41b, and the first main layer 41c in this order from the side of the dielectric layer 1. Next, the resist pattern 9 is removed by any appropriate method.

[0049] As a result of the above, an infrared heater 100 is manufactured, which has a structure of the conductor pattern 4 including a plurality of first conductors 41 / dielectric layer 1 / second conductors 2 / support substrate 5 as shown in FIG.

[0050] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0051] Examples 1 to 4 First, a 625 μm thick quartz wafer was prepared as a support substrate. A third adhesive layer, a third barrier layer, a second main layer, a second barrier layer, and a second adhesive layer were deposited on the support substrate in this order by sputtering. This resulted in a second conductor portion comprising the second adhesive layer, the second barrier layer, the second main layer, the third barrier layer, and the third adhesive layer. The metal materials constituting each of the second adhesive layer, the second barrier layer, the second main layer, the third barrier layer, and the third adhesive layer, as well as the thickness of each layer, are shown in Table 1.

[0052] Next, alumina (Al ２ O ３ The thickness of the dielectric layer is shown in Table 1.

[0053] Next, a resist pattern was formed on the dielectric layer by photolithography. The resist pattern had openings corresponding to the multiple first conductor portions of the conductor pattern. Next, a first adhesive layer, a first barrier layer, and a first main layer were deposited in this order on the portions of the dielectric layer exposed from the resist pattern by vapor deposition. This resulted in a conductor pattern being formed on the dielectric layer. The conductor pattern included multiple first conductor portions forming a periodic structure. Each of the multiple first conductor portions included a first main layer, a first barrier layer, and a first adhesive layer. The metal materials constituting each of the first main layer, the first barrier layer, and the first adhesive layer, as well as the thicknesses of each layer, are shown in Table 1. Each first conductor portion had a circular shape when viewed from the thickness direction. The diameter of each first conductor portion was 2.3 μm. The period of the multiple first conductor portions was 4.3 μm. The resist pattern was then removed.

[0054] As a result, an infrared heater having a structure of conductor pattern including a plurality of first conductors / dielectric layer / second conductors / support substrate was obtained.

[0055] <<Heat Endurance Test>> The obtained infrared heater was subjected to a heat endurance test. More specifically, the infrared heater was placed in a heating furnace and left standing at 650°C for the time shown in Table 1. Note that "0 hr" in Table 1 refers to the start of the heat endurance test (i.e., before heating). Furthermore, "10 hr x 5" in Table 1 means that the infrared heater was placed in a heating furnace, heated at 650°C for 10 hours, and then removed from the furnace and cooled to room temperature (23°C), and this cycle was repeated five times. Next, the infrared heater after the heat endurance test shown in Table 1 was allowed to radiate infrared light from the radiation surface of the dielectric layer at room temperature. The normal incidence hemispherical reflectance of the infrared light was measured in the wavelength range of 2.0 μm to 12.0 μm using a Fourier transform infrared spectrometer (FT-IR) equipped with an integrating sphere, and the normal emissivity was calculated using the above formula (1). The maximum normal emissivity of infrared light is shown in Table 1. In addition, in Figure 4, the infrared emissivity curve for the infrared heater of Example 2 at "0 hr" is shown by a dotted line, and the infrared emissivity curve for the infrared heater of Example 2 at "10 hr x 5" is shown by a solid line. The infrared emissivity curve can be obtained by plotting the wavelength of infrared rays emitted by the infrared heater versus normal emissivity. Furthermore, Figure 6 shows the infrared emissivity curve for the infrared heater of Example 2, Figure 7 shows the infrared emissivity curve for the infrared heater of Example 3, and Figure 8 shows the infrared emissivity curve for the infrared heater of Example 4. In Figures 6 to 8, the infrared emissivity curve for the infrared heater at "0 hr" is shown by a dotted line, the infrared emissivity curve for the infrared heater at "100 hr" is shown by a dashed-dotted line, and the infrared emissivity curve for the infrared heater at "500 hr" is shown by a solid line.

[0056] Comparative Examples 1 to 3: A 625 μm thick quartz wafer was prepared as a support substrate. A third adhesive layer, a second main layer, and a second adhesive layer were formed on the support substrate in this order by sputtering. This resulted in a second conductor portion including the second adhesive layer, the second main layer, and the third adhesive layer, but not including a second barrier layer. The metal materials and thicknesses of the second adhesive layer, the second main layer, and the third adhesive layer are shown in Table 1.

[0057] Next, alumina (Al ２ O３ The thickness of the dielectric layer is shown in Table 1.

[0058] Next, a resist pattern was formed on the dielectric layer by photolithography. The resist pattern had openings corresponding to the multiple first conductor portions of the conductor pattern. Next, a first adhesive layer and a first main layer were deposited in this order by vapor deposition on the portions of the dielectric layer exposed from the resist pattern. This resulted in a conductor pattern on the dielectric layer. The conductor pattern included multiple first conductor portions forming a periodic structure. Each first conductor portion included a first adhesive layer and a first main layer, but did not include a first barrier layer. The metal materials and thicknesses of the first main layer and the first adhesive layer are shown in Table 1. Each first conductor portion had a circular shape when viewed in the thickness direction. The diameter of each first conductor portion was 2.3 μm. The period of the multiple first conductor portions was 4.3 μm. The resist pattern was then removed.

[0059] This resulted in an infrared heater in which neither the first conductor nor the second conductor had a barrier layer. The infrared heater was subjected to the heating durability test described above. The results are shown in Table 1. In addition, in Figure 5, the infrared emissivity curve for the infrared heater of Comparative Example 2 at "0 hr" is shown by a dotted line, and the infrared emissivity curve for the infrared heater of Comparative Example 2 at "10 hr x 5" is shown by a solid line.

[0060]

[0061] <Evaluation> As shown in Table 1 and Figures 4 to 8, it was confirmed that the infrared heaters (Examples 1 to 4) having a first barrier layer between the first adhesive layer and the first main layer have superior heat resistance compared to the infrared heaters (Comparative Examples 1 to 3) not having a barrier layer. More specifically, the infrared heaters of Comparative Examples 1 to 3 had a maximum normal emissivity of less than 0.8 after a 10-hour heating durability test at 650°C was repeated five times. In contrast, the infrared heaters of Examples 1 to 4 had a maximum normal emissivity of 0.8 or more, even after a 10-hour heating durability test at 650°C was repeated five times, demonstrating excellent heat resistance.

[0062] In particular, the infrared heater of Example 2 was confirmed to have a maximum normal emissivity of 0.8 or higher even after a 500-hour heating endurance test at 650°C. Therefore, the shapes of the first conductors of the infrared heaters of Examples 2 to 4 after a 500-hour heating endurance test at 650°C were confirmed using a scanning electron microscope (SEM). The SEM photographs are shown in Figures 10 to 12. For comparison, Figure 9 shows an SEM photograph of the first conductor of the infrared heater of Example 2 before the heating endurance test. The magnification of the SEM photograph is 30,000 times. As is clear from Figures 9 to 12, Example 2 exhibits more suppressed grain growth during the heating endurance test, and thus less deformation of the pattern shape of the first conductor.

[0063] The infrared heater according to the embodiment of the present invention can be used in the manufacture of various industrial products, and can be particularly suitably used in the manufacture of film products, organic synthesis products, and the like.

[0064] REFERENCE SIGNS LIST 1 Dielectric layer 2 Second conductor portion 2a Second adhesive layer 2b Second barrier layer 2c Second main body layer 3a Third adhesive layer 3b Third barrier layer 4 Conductive pattern 41 First conductor portion 41a First adhesive layer 41b First barrier layer 41c First main body layer 5 Support substrate 6 Heating portion 10 Metamaterial structure 100 Infrared heater

Claims

1. An infrared heater comprising: a dielectric layer; a conductor pattern arranged on the dielectric layer, the conductor pattern including a plurality of first conductor portions arranged at intervals from each other to form a periodic structure; and a second conductor portion arranged on the opposite side of the dielectric layer to the conductor pattern, wherein each of the plurality of first conductor portions comprises: a first adhesive layer in contact with the dielectric layer; a first body layer arranged on the opposite side of the dielectric layer to the first adhesive layer; and a first barrier layer arranged between the first adhesive layer and the first body layer, the first barrier layer preventing migration of a material constituting the first adhesive layer to the first body layer.

2. The infrared heater according to claim 1, wherein the thickness of the first barrier layer is 0.2 nm or more and 50 nm or less.

3. The infrared heater according to claim 1, wherein the material constituting the first barrier layer contains a platinum group element and / or an oxide thereof.

4. An infrared heater as described in claim 1, wherein the second conductor portion comprises: a second adhesive layer in contact with the dielectric layer; a second body layer arranged on the opposite side of the second adhesive layer to the dielectric layer; and a second barrier layer arranged between the second adhesive layer and the second body layer, the second barrier layer preventing migration of a material constituting the second adhesive layer to the second body layer.

5. The infrared heater according to claim 4, further comprising a support substrate arranged on the opposite side of said second conductor portion from said dielectric layer.

6. An infrared heater as described in claim 5, wherein the second conductor portion comprises: a third adhesive layer in contact with the support substrate; and a third barrier layer disposed between the third adhesive layer and the second main body layer, the third barrier layer preventing migration of a material constituting the third adhesive layer to the second main body layer.

7. An infrared heater as described in claim 1, wherein the thickness of each of the multiple first conductor parts is 30 nm or more and 200 nm or less, when each of the multiple first conductor parts has a rectangular shape when viewed in the thickness direction, the length of one side of the first conductor part is 500 nm or more and 8000 nm or less, and when each of the multiple first conductor parts has a circular shape when viewed in the thickness direction, the diameter of the first conductor part is 500 nm or more and 8000 nm or less.

8. The infrared heater according to claim 1, wherein the distance between adjacent first conductors among the plurality of first conductors is not less than 300 nm and not more than 4000 nm.

9. The infrared heater according to claim 1, further comprising a heating section capable of heating the metamaterial structure constituted by the dielectric layer, the plurality of first conductor sections, and the second conductor section.

10. The infrared heater according to claim 9, wherein the metamaterial structure is configured such that a resonance phenomenon occurs due to magnetic polaritons when the heating portion is heated, the infrared heater is capable of emitting infrared rays having a maximum peak with a normal emissivity of 0.8 or more, the peak wavelength of the maximum peak being 2 μm or more and 10 μm or less, and the half-width of the maximum peak being 1.5 μm or less.

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