Wavelength control emitter

Abstract

Provided is a wavelength control emitter having excellent heat resistance. A wavelength control emitter according to an embodiment of the present invention comprises a metal layer, a dielectric layer, a plurality of metal electrodes, and a coating layer. The dielectric layer is disposed on one side of the metal layer. The plurality of metal electrodes are arranged on the opposite side to the metal layer with respect to the dielectric layer. The plurality of metal electrodes are arranged at intervals from each other. The coating layer covers at least a part of the plurality of metal electrodes.

Description

Wavelength Controlled Emitter

[0001] The present invention relates to a wavelength-controlled emitter.

[0002] Infrared emitters that emit infrared rays have been known. Such infrared emitters are desired to emit narrow-band infrared rays in order to efficiently impart energy to an object. For example, an infrared heater has been proposed that includes a first conductor layer including a plurality of individual conductor layers forming a periodic structure, a dielectric layer, and a second conductor layer, in this order, and is capable of emitting infrared rays having a full width at half maximum of 1.5 μm or less and a maximum peak emissivity of 0.8 or more (see, for example, Patent Document 1). In recent years, the applications of infrared emitters have become more diverse, and infrared heaters may be exposed to high-temperature environments (e.g., 400°C or higher). Therefore, improvements in the heat resistance of infrared heaters are desired.

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

[0004] A primary object of the present invention is to provide a wavelength-controlled emitter having excellent heat resistance.

[0005] [1] A wavelength control emitter according to an embodiment of the present invention includes a metal layer, a dielectric layer, a plurality of metal electrodes, and a covering layer. The dielectric layer is disposed on one side of the metal layer. The plurality of metal electrodes are disposed on the opposite side of the dielectric layer from the metal layer. The plurality of metal electrodes are arranged at intervals from one another. The covering layer covers at least a portion of the plurality of metal electrodes. [2] The wavelength control emitter described in [1] above may further include a support substrate. The support substrate is disposed on the opposite side of the metal layer from the dielectric layer.

[0006] According to the embodiment of the present invention, a wavelength-controlled emitter having excellent heat resistance can be realized.

[0007] FIG. 1 is a schematic cross-sectional view of a wavelength-controlled emitter according to one embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II' of the metal electrode of FIG. 1. FIG. 3A is a schematic cross-sectional view illustrating a step of preparing a support substrate in a method for manufacturing a wavelength-controlled emitter according to one embodiment of the present invention. FIG. 3B is a schematic cross-sectional view illustrating a step of forming a metal layer on the support substrate of FIG. 3A. FIG. 3C is a schematic cross-sectional view illustrating a step of forming a dielectric layer on the metal layer of FIG. 3B. FIG. 3D is a schematic cross-sectional view illustrating a step of forming a resist pattern on the dielectric layer of FIG. 3C. FIG. 3E is a schematic cross-sectional view illustrating a step of forming multiple metal electrodes on the dielectric layer via the resist pattern of FIG. 3D. FIG. 3F is a schematic cross-sectional view illustrating a step of forming a coating layer that covers the metal electrode of FIG. 3E. FIG. 4 is a graph showing infrared emissivity curves for the wavelength-controlled emitters of Examples 1 to 4. FIG. 5 is a graph showing infrared emissivity curves for the wavelength-controlled emitter of Example 2 before and after a heating durability test. FIG. 6 is a graph showing infrared emissivity curves for the wavelength-controlled emitter of Example 5. 7A is a graph showing infrared emissivity curves before a heating durability test for the wavelength control emitters of Examples 6 and 7 and Comparative Examples 1 and 2. FIG. 7B is a graph showing infrared emissivity curves after a heating durability test for the wavelength control emitters of Examples 6 and 7 and Comparative Examples 1 and 2.

[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 Wavelength-Controlled Emitter Figure 1 is a schematic cross-sectional view of a wavelength-controlled emitter according to one embodiment of the present invention, and Figure 2 is a cross-sectional view of the metal electrode taken along line II-II' in Figure 1. Note that hatching has been omitted in Figure 2 for the sake of convenience.

[0010] The wavelength-controlled emitter 100 shown in the figure can emit infrared light with a controlled wavelength, more specifically, infrared light with a controlled wavelength at which the normal emissivity is maximized (hereinafter referred to as the maximum emissivity wavelength). In other words, the wavelength-controlled emitter 100 functions as an infrared emitter. Such a wavelength-controlled emitter 100 is suitable for use, for example, as a wavelength-controlled heater (infrared heater). As shown in FIG. 1 , the wavelength-controlled emitter 100 includes a metal layer 2, a dielectric layer 3, multiple metal electrodes 4, and a coating layer 5. The dielectric layer 3 is disposed on one side of the metal layer 2. The multiple metal electrodes 4 are disposed on the opposite side of the dielectric layer 3 from the metal layer 2. The multiple metal electrodes 4 are arranged at intervals from one another. In other words, the dielectric layer 3 is disposed between the metal layer 2 and the multiple metal electrodes 4. The metal layer 2, the dielectric layer 3, and the multiple metal electrodes 4 typically form a metamaterial structure. The coating layer 5 is disposed on the opposite side of the dielectric layer 3 from the metal layer 2. The coating layer 5 covers at least a portion of the multiple metal electrodes 4. The inventors discovered that when a wavelength-controlled emitter is exposed to a high-temperature environment (e.g., 400°C or higher), the maximum emissivity wavelength of the infrared rays emitted by the wavelength-controlled emitter shifts to a lower wavelength. Therefore, after extensive research into improving the heat resistance of the wavelength-controlled emitter, they discovered that by coating the multiple metal electrodes, the shift in the maximum emissivity wavelength of the infrared rays emitted by the wavelength-controlled emitter to a lower wavelength can be suppressed even when the wavelength-controlled emitter is exposed to a high-temperature environment. Specifically, covering the metal electrodes with a coating layer arranged on the opposite side of the dielectric layer from the metal layer can suppress changes in the metal electrodes caused by heat (e.g., sagging of the metal electrodes due to heat). Therefore, the shift in the maximum emissivity wavelength of the infrared rays can be suppressed and the maximum normal emissivity of the infrared rays can be sufficiently ensured. This can sufficiently improve the heat resistance of the wavelength-controlled emitter.

[0011] The wavelength-controlled emitter 100 shown in the figure is capable of selectively emitting infrared light with a controlled maximum emissivity wavelength, typically due to a metamaterial structure formed by a metal layer 2, a dielectric layer 3, and multiple metal electrodes 4. Specifically, a magnetic resonance phenomenon in which electromagnetic waves of a specific wavelength are strengthened may occur between the metal layer 2, the dielectric layer 3, and the multiple metal electrodes 4. As a result, each metal electrode 4 and the underlying dielectric layer 3 and metal layer 2 function as a set as a radiation source of infrared light that can propagate outside the electrode 4, and infrared light with a controlled maximum emissivity wavelength is radiated into the far field from the entire surface of the emitter by combining the radiation from all of these sets.

[0012] The maximum emissivity wavelength of the emitted infrared rays (hereinafter sometimes referred to as the peak wavelength) 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 maximum normal emissivity of infrared rays is, for example, 0.8 or more, preferably 0.9 or more. On the other hand, the upper limit of the maximum normal emissivity of infrared rays is typically 1.0. Note that the normal emissivity of infrared rays is calculated, for example, by applying Kirchhoff's law with transmittance set to a value of 0, using the following formula (1). Note that the normal reflectance is measured, for example, using a Fourier transform infrared spectrophotometer (FT-IR) equipped with an integrating sphere: (Normal emissivity) = 1 - (Normal reflectance) (1) In the infrared emissivity curve (see FIG. 4) obtained by plotting the infrared wavelength and normal emissivity, the half-width of the peak corresponding to the maximum emissivity wavelength (hereinafter referred to as the maximum peak) is, for example, 1.5 μm or less, preferably 1.0 μm or less. On the other hand, the lower limit of the half-width of the maximum peak is typically 0.3 μm. In the wavelength range of 2.0 μm to 10 μm in the infrared emissivity curve described above, it is preferable that, except for the maximum peak, there be no peaks with a normal emissivity of 0.2 or more. In the wavelength range of 2.0 μm to 10 μm in the infrared emissivity curve described above, the area of ​​the maximum peak is, for example, 50% to 100% or less of the total peak area. The integrated wavelength range used to determine the maximum area is twice the half-width, centered on the peak wavelength.

[0013] In one embodiment, wavelength-controlled emitter 100 further includes a support substrate 1. Support substrate 1 is disposed on the opposite side of metal layer 2 from dielectric layer 3. This allows the support substrate to stably support the metamaterial structure described above.

[0014] Wavelength-controlled emitter 100 can have any appropriate shape. Examples of the shape of wavelength-controlled emitter 100 when viewed from a direction perpendicular to the II-II' cross section (plane direction) of FIG. 1 include a triangle, a rectangle, a pentagon, a polygon with hexagons or more, a circle, an ellipse, a cross, and the like.

[0015] The following describes in detail each component of the wavelength-controlled emitter. The design values ​​described as examples should be designed according to the target wavelength, but as a representative example, the case where the target peak wavelength is 3.7 μm will be described in detail.

[0016] B. Support Substrate The support substrate 1 can provide excellent mechanical strength to the wavelength-controlled emitter 100. Any suitable substrate that can be used for a wavelength-controlled emitter can be adopted as the support substrate 1. The support substrate 1 typically has a substantially flat plate shape. Examples of materials that can be used to form the support substrate 1 include materials with excellent heat resistance. Specifically, sapphire, silicon (Si), quartz, soda glass, zirconia, and LiTaO ３ , LiNbO ３ The material constituting the support substrate 1 preferably has a thermal expansion coefficient that is approximately the same as that of the materials constituting the dielectric layer 3 and the covering layer 5 (typically, within ±10% of the thermal expansion coefficient of the material of the dielectric layer). The support substrate 1 may be composed of a single base material, or may have a layered structure in which multiple substrates are stacked. The thickness of the support substrate 1 is, for example, 100 μm to 1 mm, or, for example, 500 μm to 750 μm.

[0017] C. Metal Layer The metal layer 2 is typically provided on the surface of the support substrate 1. The metal layer 2 is electrically conductive. Examples of materials constituting the metal layer 2 include any suitable metal material capable of forming a metamaterial structure. Examples of metal materials include chromium (Cr), titanium (Ti), ruthenium (Ru), gold (Au), aluminum (Al), nickel (Ni), copper (Cu), silver (Ag), palladium (Pd), platinum (Pt), molybdenum (Mo), tungsten (W), iron (Fe), and cobalt (Co). The metal material can be used alone or as an alloy. The metal layer 2 may be composed of a single metal film or may have a layered structure in which multiple metal films are stacked. The thickness f of the metal layer 2 is, for example, 50 nm to 450 nm, and preferably 90 nm to 250 nm.

[0018] In one embodiment, the metal layer 2 has a laminated structure and includes a first main layer 21 and a first adhesive layer 22. The first main layer 21 is bonded to the support substrate 1 via the first adhesive layer 22. This improves adhesion of the metal layer to the support substrate and prevents the metal layer from peeling off from the support substrate. Furthermore, because the first adhesive layer is located between the first main layer and the support substrate, diffusion of metal elements constituting the first main layer into the support substrate can be stably prevented in high-temperature environments. Examples of metal materials constituting the first main layer 21 include gold (Au), aluminum (Al), nickel (Ni), copper (Cu), silver (Ag), palladium (Pd), platinum (Pt), molybdenum (Mo), tungsten (W), iron (Fe), and cobalt (Co), with gold (Au) being preferred. The thickness of the first main layer 21 is, for example, 50 nm to 450 nm, preferably 100 nm to 250 nm. Examples of the metal material constituting the first adhesive layer 22 include chromium (Cr), titanium (Ti), and ruthenium (Ru), and preferably chromium (Cr). The thickness of the first adhesive layer 22 is, for example, 1 nm to 30 nm, and preferably 2 nm to 4 nm.

[0019] D. Dielectric Layer The dielectric layer 3 is typically provided on the surface of the metal layer 2 opposite to the support substrate 1. In the illustrated example, the dielectric layer 3 is located on the opposite side of the first main body layer 21 from the first adhesive layer 22, and is provided on the surface of the first main body layer 21. The dielectric layer 3 has electrical insulation properties. The volume resistivity of the dielectric layer 3 at 500°C is, for example, 1×10 ７ Ω cm to 1 x 10 １２ The dielectric constant of the dielectric layer 3 at 10 GHz is, for example, 9 to 10, and preferably 9.5 to 9.8.

[0020] The material for the dielectric layer 3 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 ), titania (TiO ２ ), preferably alumina. The inorganic oxides can be used alone or in combination. The dielectric layer 3 may be composed of a single layer, or may have a laminated structure in which multiple layers are stacked. In the illustrated example, the dielectric layer 3 is composed of a single layer. The thickness d of the dielectric layer 3 is, for example, 20 nm to 300 nm, and preferably 30 nm to 150 nm. When the thickness of the dielectric layer is in this range, the maximum emissivity wavelength of infrared rays can be stably adjusted to the above range.

[0021] E. Metal Electrodes The plurality of metal electrodes 4 are typically provided on the surface of the dielectric layer 3 opposite to the metal layer 2. The plurality of metal electrodes 4 are arranged at equal intervals on the dielectric layer 3 to form a periodic structure. More specifically, rows of the plurality of metal electrodes 4 arranged at equal intervals in a first surface direction of the dielectric layer 3 are arranged in parallel at equal intervals in a second surface direction perpendicular to the first surface direction (see FIG. 2 ).

[0022] Each of the multiple metal electrodes 4 may have any appropriate shape capable of forming a metamaterial structure. Examples of the shape of the metal electrode 4 as viewed perpendicular to the plane of FIG. 2 include a triangle, a rectangle, a pentagon, a polygon with hexagons or more, a circle, an ellipse, and a cross. The dimensions of the metal electrode 4 in the plane direction of the dielectric layer (the first plane direction or the second plane direction) can be arbitrarily and appropriately adjusted according to the desired maximum emissivity wavelength. When the metal electrode 4 has a rectangular shape, the length (width) w of one side of the metal electrode 4 is, for example, 300 nm to 5000 nm, preferably 400 nm to 4000 nm. When the metal electrode 4 has a circular shape, the range of the diameter (width) of the metal electrode 4 is, for example, the same as the range of the width w described above. The shapes and sizes of the multiple metal electrodes 4 may all be the same, or at least some may be different. Preferably, the shapes and sizes of the multiple metal electrodes 4 are all the same. The period Λ of the periodic structure formed by the multiple metal electrodes 4 can be arbitrarily and appropriately adjusted depending on the desired maximum emissivity wavelength. When the metal electrodes 4 have a square shape as viewed perpendicular to the plane of the paper in FIG. 2, the period Λ is desirably set to a value in the range of approximately 1.2 to 3.0 times the electrode dimension w (see FIG. 2).

[0023] Each of the multiple metal electrodes 4 has electrical conductivity. Examples of materials constituting the metal electrode 4 include the metal materials constituting the metal layer 2 described above. The metal materials can be used alone or in combination. The metal electrode 4 may be composed of a single metal film, or may have a layered structure in which multiple metal films are stacked. The thickness h of the metal electrode 4 is, for example, 20 nm to 200 nm, and preferably 40 nm to 100 nm. When the thickness of the metal electrode is within this range, the maximum emissivity wavelength of infrared light can be stably adjusted within the above range.

[0024] In one embodiment, the metal electrode 4 has a laminated structure and includes a second main body layer 41 and a second adhesive layer 42. The second main body layer 41 is bonded to the dielectric layer 3 via the second adhesive layer 42. This improves adhesion of the metal electrode to the dielectric layer and prevents the metal electrode from peeling off from the dielectric layer. Furthermore, since the second adhesive layer is located between the second main body layer and the dielectric layer, diffusion of the metal material constituting the second main body layer into the dielectric layer can be prevented in high-temperature environments. Examples of metal materials constituting the second main layer 41 include those similar to the metal materials constituting the first main layer 21 described above. In one embodiment, the first main layer 21 and the second main layer 41 are composed of the same metal material. The thickness of the second main layer 41 is, for example, 20 nm to 200 nm, preferably 40 nm to 100 nm. Examples of metal materials constituting the second adhesive layer 42 include those similar to the metal materials constituting the first adhesive layer 22 described above. In one embodiment, the first adhesive layer 22 and the second adhesive layer 42 are made of the same metal material. The thickness of the second adhesive layer 42 is, for example, 1 nm to 30 nm, and preferably 2 nm to 4 nm.

[0025] F. Coating Layer The coating layer 5 is typically provided directly on the surface of the dielectric layer 3 opposite the metal layer 2 so as to cover at least a portion of the plurality of metal electrodes 4. In the illustrated example, the coating layer 5 covers all of the metal electrodes 4. The coating layer 5 has electrical insulation properties. The range of the volume resistivity of the coating layer 5 at 500°C is, for example, the same as the range of the volume resistivity of the dielectric layer 3. The infrared transmittance of the coating layer 5 may be set higher than the infrared transmittance of the metal electrodes 4. The infrared transmittance of the coating layer is measured, for example, by FT-IR.

[0026] The coating layer 5 is typically made of a material that does not easily disperse the metal material that constitutes the metal electrode 4 in a high-temperature environment (e.g., 450°C or higher). The metal material of the metal electrode 4 preferably does not easily disperse in the coating layer 5, and it is desirable that the dispersion is 1% or less, for example, as determined by EDS elemental analysis (energy dispersive spectroscopy). Examples of materials that constitute the coating layer 5 include the inorganic oxides that constitute the dielectric layer 3 described above, and alumina is preferred. The inorganic oxides can be used alone or in combination.

[0027] The coating layer 5 may be composed of a single layer or may have a laminated structure in which multiple layers are stacked. In the illustrated example, the coating layer 5 is composed of a single layer. The thickness dd of the coating layer 5 is, for example, 30 nm to 300 nm, preferably 50 nm to 150 nm. When the thickness of the coating layer 5 (particularly the thickness of the coating layer 5 located on the metal electrode) is within this range, heat-induced changes in the metal electrode (e.g., diffusion of the metal electrode due to heat) can be sufficiently suppressed even when the wavelength-controlled emitter is exposed to a high-temperature environment. The thickness dd of the coating layer 5 is, for example, 1 to 3 times, preferably 1.2 to 2.0 times, the thickness h of the metal electrode 4. When the thickness of the coating layer is within this range, the coating layer can stably cover the metal electrode. Because the refractive index on the top surface of the metal electrode 4 changes depending on whether the coating layer 5 is present or absent, the peak wavelength differs depending on whether the coating layer 5 is present or absent. The peak wavelength will not match the target value simply by providing a coating layer 5 to provide heat resistance to a wavelength-controlled emitter whose peak wavelength matches the target value without the coating layer 5. In order to match the peak wavelength to the target value when the coating layer 5 is present, it is necessary to design the above parameters using numerical analysis by computer simulation or the like for the shape when the coating layer 5 is present.

[0028] G. Other Configurations Although not shown, the wavelength-controlled emitter 100 may further include a heating unit. The heating unit can heat the metamaterial structure described above. The heating unit is, for example, disposed on the opposite side of the support substrate 1 from the metal layer 2. The heating unit is preferably bonded to the support substrate 1 via an adhesive layer. The adhesive layer can be described in the same manner as the first adhesive layer described above. The configuration of the heating unit is not particularly limited. Any appropriate heat generating unit can be adopted as the heating unit.

[0029] H. Method for Manufacturing Wavelength-Controlled Emitter Next, one embodiment of a method for manufacturing wavelength-controlled emitter 100 will be described with reference to Figures 3A to 3F. In one embodiment, target values ​​for the maximum emissivity wavelength and maximum emissivity of infrared light emitted by the wavelength-controlled emitter to be manufactured are set in advance. Next, the target values ​​for the maximum emissivity wavelength and maximum emissivity are numerically analyzed, for example, by computer simulation, to determine in advance the calculated values ​​for the thickness dd of coating layer 5, the thickness h of metal electrode 4, the thickness d of dielectric layer 3, the width w of metal electrode 4, and the period Λ of metal electrode 4 that correspond to these target values ​​(see Figure 1).

[0030] Next, as shown in FIG. 3A , the above-described support substrate 1 is prepared. Then, as shown in FIG. 3B , the above-described metal layer 2 is formed on the support substrate 1 by any appropriate film formation method. Examples of methods for forming the metal layer 2 include sputtering, plating, and vapor deposition, with sputtering being preferred. In the illustrated example, the metal layer 2 has a laminated structure (first adhesive layer 22 and first main layer 21). In this case, the above-described film formation method is repeated to form the first adhesive layer 22 and the first main layer 21 in this order.

[0031] 3C , the above-described dielectric layer 3 is formed on the metal layer 2 so that the thickness d of the dielectric layer 3 is the above-calculated value. Typically, the dielectric layer 3 is formed on the metal layer 2. Examples of methods for forming the dielectric layer 3 include atomic layer deposition (ALD) and chemical vapor deposition (CVD).

[0032] Next, as shown in FIGS. 3D and 3E , the above-described multiple metal electrodes 4 are formed on the dielectric layer 3 so that the thickness h of each metal electrode 4 is the calculated value. In one embodiment, as shown in FIG. 3D , a resist pattern 9 is first formed on the dielectric layer 3. The resist pattern 9 is typically formed by maskless lithography using electron beam (EB) lithography. This allows openings corresponding to the multiple metal electrodes to be accurately formed in the resist pattern 9. The size of the openings corresponds to the calculated value of the width w of the metal electrodes. Next, as shown in FIG. 3E , the above-described multiple metal electrodes 4 are formed on the portions of the dielectric layer 3 exposed by the resist pattern 9 using any appropriate film formation method. Examples of film formation methods for the metal electrodes 4 include sputtering, plating, and vapor deposition, with sputtering being preferred and helicon sputtering being more preferred. In the illustrated example, each metal electrode 4 has a laminated structure (a second adhesive layer 42 and a second main layer 41). In this case, the above-described film formation method is repeated to form the second adhesive layer 42 and the second main body layer 41 in this order, after which the resist pattern 9 is removed by any appropriate method.

[0033] The method for forming the plurality of metal electrodes 4 is not limited to the above. For example, after a metal film is formed on the dielectric layer by the above-described film formation method, a resist pattern that covers only the portions of the metal film that correspond to the plurality of metal electrodes may be formed on the metal film, and the metal film may be etched through the resist pattern by any appropriate method. This method also allows the above-described plurality of metal electrodes 4 to be formed on the dielectric layer 3.

[0034] 3F , the coating layer 5 is formed on the dielectric layer 3 so that the thickness dd of the coating layer 5 is the calculated value. Typically, the coating layer 5 is formed on the dielectric layer 3. Examples of methods for forming the coating layer 5 include atomic layer deposition (ALD) and chemical vapor deposition (CVD).

[0035] By the above steps, wavelength-controlled emitter 100 having a structure of covering layer / plurality of metal electrodes / dielectric layer / metal layer / support substrate is manufactured.

[0036] Such a wavelength-controlled emitter 100 can emit infrared light having a specific maximum emissivity wavelength. The actual measured value of the infrared maximum emissivity wavelength is, for example, within ±50 nm of the target value of the maximum emissivity wavelength, and preferably within ±10 nm of the target value of the maximum emissivity wavelength. The actual measured value of the infrared maximum emissivity wavelength may deviate from the target value due to differences between the optical characteristics of each layer used in the numerical analysis and the optical characteristics of each layer actually fabricated, and / or the proximity effect during electron beam writing or the halation effect during laser writing or stepper writing.

[0037] In one embodiment, the calculated value of the width w of the metal electrode 4 is corrected based on the following formula (2). When a wavelength-controlled emitter is manufactured using such a corrected value of the width w of the metal electrode 4, the actual measured value of the maximum emissivity wavelength of the infrared light emitted by the manufactured wavelength-controlled emitter can be brought closer to the target value of the maximum emissivity wavelength. Specifically, the actual measured value of the maximum emissivity wavelength of the infrared light can be stably adjusted to within ±10 nm of the target value of the maximum emissivity wavelength. (In the above formula (2), a １ represents the width of the metal electrode in the first sample; a ２ represents the width of the metal electrode in the second sample; b ０ represents the target value of the maximum emissivity wavelength; b １ represents the measured value of the maximum emissivity wavelength of infrared light emitted by the first sample; b ２ where x represents the actual measured value of the maximum emissivity wavelength of infrared radiation emitted by the second sample; and x represents the correction value for the width of the metal electrode that is expected to be the target value of the maximum emissivity wavelength. The first sample is a wavelength-controlled emitter manufactured in advance using the same method as above. The second sample is a wavelength-controlled emitter manufactured in the same manner as the first sample, except that the width of the metal electrode is changed. The width of the metal electrode included in the second sample is, for example, 101% to 125%, or for example, 105% to 115%, when the width of the metal electrode included in the first sample is taken as 100%.

[0038] This allows for the calculation of a correction value x for the width of the metal electrode that is expected to result in a target value for the maximum emissivity wavelength. A wavelength-controlled emitter (third sample) with a precisely controlled maximum emissivity wavelength can be manufactured using the same manufacturing method as the first sample, except for using this correction value x. In one embodiment, the width of the metal electrode in the third sample is larger than the width of the metal electrode in the first sample and smaller than the width of the metal electrode in the second sample. In another embodiment, the width of the metal electrode in the third sample may be larger or smaller than both the width of the metal electrode in the first sample and the width of the metal electrode in the second sample. The width of the metal electrode in the third sample is, for example, 101% to 120%, or for example, 102% to 110%, when the width of the metal electrode in the first sample is 100%.

[0039] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0040] Example 1 First, the target value of the maximum emissivity wavelength of the infrared ray emitted by the wavelength-controlled emitter to be manufactured was set to 5.882 μm, and the target value of the maximum emissivity of the infrared ray was set to 0.9. The shape of the metal electrode to be formed was set to a square shape when viewed perpendicular to the plane of the paper in FIG. 2 . Next, the target values ​​of the maximum emissivity wavelength and the maximum emissivity were numerically analyzed, and the corresponding calculated value of the thickness dd of the coating layer was obtained. Similarly to the calculation of the thickness dd of the coating layer, the calculated values ​​of the thickness h of the metal electrode, the thickness d of the dielectric layer, and the dimension (width) w of one side of the metal electrode were also obtained.

[0041] Next, a 525 nm thick sapphire substrate (support substrate) was prepared. A metal film (first adhesive layer, 4 nm thick) composed of Cr and a metal film (first main layer, 200 nm thick) composed of Au were deposited on the sapphire substrate by sputtering in this order. This resulted in a metal layer comprising the first adhesive layer and the first main layer. The thickness f of the metal layer is shown in Table 1.

[0042] Then, alumina (Al ２ O ３The thickness d of the dielectric layer is shown in Table 1.

[0043] Next, a resist pattern was formed on the dielectric layer by maskless lithography. The resist pattern had openings corresponding to the multiple metal electrodes in the dielectric layer. The size of the openings corresponded to the calculated value of the width w of the metal electrodes described above. Next, a metal film (second adhesive layer) composed of Cr and a metal film (second main body layer) composed of Au were deposited in this order by sputtering on the portions of the dielectric layer exposed from the resist pattern. This resulted in multiple metal electrodes comprising the second adhesive layer and the second main body layer, each with a thickness that met the calculated value. The multiple metal electrodes formed a periodic structure. The width w and thickness h of the metal electrodes, and the period Λ of the periodic structure are shown in Table 1. The resist pattern was then removed.

[0044] Next, alumina (Al ２ O ３ ) was deposited by the ALD method so that the thickness dd was the calculated value described above.

[0045] This resulted in a wavelength-controlled emitter having a structure of coating layer / multiple metal electrodes / dielectric layer / metal layer / sapphire substrate (support substrate). At room temperature (23°C), the infrared emissivity from the emitting surface of the dielectric layer of the wavelength-controlled emitter was calculated by measuring reflectance using a Fourier transform infrared spectrometer. The normal incidence hemispherical reflectance of the infrared light was measured in the wavelength range of 4.5 μm to 7.5 μm using a Fourier transform infrared spectrometer with an integrating sphere, and the normal emissivity was calculated using the above formula (1). Figure 4 shows an infrared emissivity curve A obtained by plotting the infrared wavelength and normal emissivity. Furthermore, the measured value of the maximum emissivity wavelength of the infrared light and the half-width of the maximum peak were calculated from the infrared emissivity curve A in Figure 4. The results are shown in Table 1.

[0046] Example 2 A wavelength control emitter was prepared in the same manner as in Example 1, except that the width w of the metal electrode was changed to the value shown in Table 1, and the infrared emissivity curve B of the wavelength control emitter was obtained. The results are shown in Table 1 and FIG. 4. The wavelength control emitter was then subjected to a heating endurance test, and left to stand at 650°C for one week. Thereafter, the infrared emissivity curve B' of the wavelength control emitter after the heating endurance test was obtained in the same manner as above. The results are shown in Table 1 and FIG. 5.

[0047] Example 3 A wavelength-controlled emitter was prepared in the same manner as in Example 1, except that the width w of the metal electrode was changed to the value shown in Table 1, and the infrared emissivity curve C of the wavelength-controlled emitter was determined. The results are shown in Table 1 and FIG.

[0048] Example 4 A wavelength-controlled emitter was prepared in the same manner as in Example 1, except that the width w of the metal electrode was changed to the value shown in Table 1, and the infrared emissivity curve D of the wavelength-controlled emitter was obtained. The results are shown in Table 1 and FIG.

[0049] Example 5 Next, a wavelength control emitter was prepared in the same manner as in Example 1, except that the calculated value of the width w of the metal electrode was changed to a correction value calculated as follows, and the infrared emissivity curve E of the wavelength control emitter was determined. The results are shown in Table 1 and Figure 6. <<Calculation of Correction Value>> The wavelength control emitter of Example 3 was used as the first sample, and the wavelength control emitter of Example 4 was used as the second sample. Based on the widths and infrared emissivity curves of these metal electrodes, a correction value (1437 nm) for the width of the metal electrode was calculated using the above formula (2).

[0050] Example 6 A wavelength control emitter was prepared in the same manner as in Example 1, except that the target value of the maximum emissivity wavelength was changed to 3.70 μm, and the calculated values ​​of the coating layer thickness dd, metal electrode thickness h, dielectric layer thickness d, metal electrode width w, and metal electrode period Λ were determined. The infrared emissivity curve F of the wavelength control emitter was obtained. The results are shown in Table 2 and FIG. 7A. The wavelength control emitter was then subjected to a heating endurance test and left to stand at 600°C for one week. Thereafter, the infrared emissivity curve F' of the wavelength control emitter after the heating endurance test was obtained in the same manner as above. The results are shown in Table 2 and FIG. 7B.

[0051] Example 7 A wavelength control emitter was prepared in the same manner as in Example 6, except that the width w of the metal electrode and the thickness dd of the coating layer were changed to the values ​​shown in Table 2. The infrared emissivity curve G of the wavelength control emitter and the infrared emissivity curve G' of the wavelength control emitter after the heating durability test were obtained. The results are shown in Table 2 and Figures 7A and 7B.

[0052] Comparative Example 1 A wavelength control emitter was prepared in the same manner as in Example 6, except that no coating layer was provided and the width w of the metal electrode was changed to achieve a target wavelength of 3.70 μm. The infrared emissivity curve H of the wavelength control emitter and the infrared emissivity curve H' of the wavelength control emitter after the heating durability test were obtained. The results are shown in Table 2 and Figures 7A and 7B.

[0053] Comparative Example 2 A wavelength control emitter was prepared in the same manner as in Comparative Example 1, except that the width w of the metal electrode was changed to the value shown in Table 2. The infrared emissivity curve I of the wavelength control emitter and the infrared emissivity curve I' of the wavelength control emitter after the heating durability test were obtained. The results are shown in Table 2 and Figures 7A and 7B.

[0054]

[0055]

[0056] 7B, it was confirmed that the wavelength control emitters with a coating layer (Examples 6 and 7) had superior heat resistance compared to the wavelength control emitters without a coating layer (Comparative Examples 1 and 2). More specifically, it was found that the wavelength control emitters of Examples 6 and 7 suppressed the shift in the maximum emissivity wavelength and adequately maintained the maximum normal emissivity even when subjected to a heat durability test.

[0057] The wavelength-controlled emitter 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.

[0058] REFERENCE SIGNS LIST 1 Support substrate 2 Metal layer 3 Dielectric layer 4 Metal electrode 5 Covering layer 100 Wavelength control emitter

Claims

1. A wavelength-controlled emitter comprising: a metal layer; a dielectric layer disposed on one side of the metal layer; a plurality of metal electrodes disposed on the opposite side of the dielectric layer from the metal layer, the plurality of metal electrodes being arranged at intervals from one another; and a covering layer covering at least a portion of the plurality of metal electrodes.

2. The wavelength-controlled emitter of claim 1, further comprising a support substrate disposed on the opposite side of said metal layer from said dielectric layer.

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