Manufacturing method of multi-layer metasurface structure and multi-layer metasurface structure

Abstract

The present invention addresses the problem of providing a method for manufacturing a multilayer metasurface structure having excellent positional accuracy between metasurface structures. The manufacturing method of the present invention comprises: a step 1 in which a spacer part containing a polymerizable compound is arranged in a pattern on a first metasurface structure; the first metasurface structural body comprises a first substrate and a first structural body layer which is arranged on at least one surface side of the first substrate and is formed by arranging a plurality of first metal fine structural bodies along the in-plane direction; and a step 2 in which the second metasurface structure is adhered to the spacer portion to obtain a laminate including the first metasurface structure, the spacer portion, and the second metasurface structure. The second metasurface structural body comprises a second substrate and a second structural body layer, wherein the second structural body layer is arranged on at least one surface side of the second substrate and is formed by arranging a plurality of second metal fine structural bodies in the in-plane direction. And a step 3 for polymerizing the polymerizable compound.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a multilayer supersurface structure formed by stacking a plurality of supersurface structures, and the multilayer supersurface structure. Background Art

[0002] In recent years, artificial materials that perform actions not found in natural materials, such as processing metals, dielectrics, and magnetic materials into structures smaller than the wavelength of electromagnetic waves, and having a negative refractive index with respect to electromagnetic waves, have attracted attention.

[0003] Among such artificial materials, a so-called super-surface structure in which metal microstructures made of metal or the like are arranged on a substrate is known as a flat-plate element.

[0004] The metasurface structure can utilize metal microstructures arranged on a substrate, for example, to apply a phase difference to a transmitted electromagnetic wave and bend the electromagnetic wave in a desired direction.

[0005] Therefore, it is expected that the metasurface structure will be applied to various elements such as convex lenses (condenser lenses) and deflection elements.

[0006] In particular, high-frequency electromagnetic waves such as so-called millimeter waves and terahertz waves (THz waves) used in large-capacity wireless communications have high straightness. Therefore, since it is necessary to control the directivity toward the communication equipment, there is a high demand for applying a phase difference to the electromagnetic waves emitted from the wave source by using an element with a convex lens effect to refract them for collimation (planarization).

[0007] Here, as described above, the metasurface structure refracts electromagnetic waves, for example, by applying a phase difference to the electromagnetic waves using the arranged metal microstructures.

[0008] This metasurface structure is in the form of a flat plate and does not require the same thickness as a conventional optical refractive lens. In addition, it does not require the formation of a concave-convex structure with a steep groove structure like a diffraction lens (Fresnel lens).

[0009] That is, by using a metasurface structure, it is possible to realize elements such as very thin flat-plate convex lenses.

[0010] However, conventional metasurface structures often fail to impart sufficient phase difference or obtain sufficient refractive index for electromagnetic waves in high-frequency bands, such as terahertz waves, and their application range as optical elements in the terahertz region is limited.

[0011] In order to solve these problems of the prior art, it is considered to improve the characteristics by stacking supersurface structures.

[0012] In response to such a demand, for example, Patent Document 1 describes a multilayer metasurface structure (laminated metamaterial film) that transmits various electromagnetic waves by laminating a plurality of metasurface structures.

[0013] Previous technical literature

[0014] Patent Literature

[0015] Patent Document 1: Japanese Patent Application Publication No. 2017-175201 Summary of the invention

[0016] Technical issues to be solved by the invention

[0017] As described in Patent Document 1, by stacking a plurality of metasurface structures, a metasurface structure that can correspond to various electromagnetic waves can be obtained.

[0018] In addition, it is believed that by stacking multiple layers of metasurface structures, a larger phase difference can be given to electromagnetic waves.

[0019] Here, in order to obtain target performance in a multilayered supersurface structure in which a plurality of supersurface structures are stacked, it is important that the stacked supersurface structures are accurately aligned with each other.

[0020] However, in the conventional manufacture of a multilayered supersurface structure in which a plurality of supersurface structures are stacked, it is difficult to align the supersurface structures with each other, and the positional accuracy of the supersurface structures is often insufficient.

[0021] The purpose of the present invention is to solve these problems of the prior art and to provide a method for manufacturing a multilayer supersurface structure which can properly align the supersurface structures with each other in the manufacture of a multilayer supersurface structure formed by stacking multiple layers of supersurface structures and can manufacture a multilayer supersurface structure with excellent positional accuracy between the supersurface structures, as well as a multilayer supersurface structure manufactured by the manufacturing method with excellent positional accuracy between the supersurface structures.

[0022] Means for solving technical problems

[0023] In order to solve the problem, the present invention has the following structure. [1]

[0025] A method for manufacturing a multi-layer supersurface structure, comprising:

[0026] Step 1, arranging a spacer portion containing a polymerizable compound in a pattern on a first supersurface structure, wherein the first supersurface structure includes a first substrate and a first structure layer provided on at least one surface side of the first substrate and including a plurality of first metal microstructures arranged along an in-plane direction;

[0027] Step 2, pasting the second super surface structure and the spacer portion to obtain a laminate including the first super surface structure, the spacer portion and the second super surface structure, wherein the second super surface structure includes a second substrate and a second structure layer formed by a plurality of second metal microstructures arranged on at least one surface side of the second substrate and arranged in an in-plane direction; and

[0028] In step 3, the polymerizable compound is polymerized. [2]

[0030] The method for manufacturing a multilayer supersurface structure according to [1], wherein step 1 comprises:

[0031] Step A, forming a photosensitive layer containing a polymerizable compound on a first supersurface structure, wherein the first supersurface structure includes a first substrate and a first structure layer formed by configuring a plurality of first metal microstructures on the first substrate and configured along an in-plane direction;

[0032] Step B, exposing the photosensitive layer into a pattern; and

[0033] In step C, the exposed photosensitive layer is subjected to a development process to form a spacer portion. [3]

[0035] The method for manufacturing a multilayer supersurface structure according to [1], wherein:

[0036] Step 1 is a step of stacking a patterned photosensitive layer containing a polymerizable compound on a first supersurface structure to form a spacer portion, wherein the first supersurface structure includes a first substrate and a first structure layer formed by configuring a plurality of first metal microstructures on the first substrate and configured along an in-plane direction. [4]

[0038] The method for manufacturing a multilayer supersurface structure according to any one of [1] to [3], wherein:

[0039] The melt viscosity of the spacer portion at 23°C is 1.0×10 5 Pa·s or more, and the melt viscosity at 80°C is less than 1.0×10 5 Pa·s. [5]

[0041] A multi-layer super surface structure, wherein:

[0042] The multilayer supersurface structure is manufactured by the method for manufacturing a multilayer supersurface structure described in any one of [1] to [4]. [6]

[0044] The multilayer supersurface structure according to [5], wherein:

[0045] The multi-layer metasurface structure is a transmission type element. [7]

[0047] The multilayer supersurface structure according to [5], wherein:

[0048] The multi-layer supersurface structure is a sheet-like superlens.

[0049] Effects of the Invention

[0050] According to the present invention, in the manufacture of a multilayer supersurface structure in which a plurality of supersurface structures are stacked, a multilayer supersurface structure having excellent positional accuracy between the supersurface structures can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a diagram conceptually showing an example of a super-surface structure manufactured by the manufacturing method of the present invention.

[0052] Figure 2 This is a diagram conceptually showing another example of a super-surface structure manufactured by the manufacturing method of the present invention.

[0053] Figure 3 This is a diagram conceptually showing another example of a super-surface structure manufactured by the manufacturing method of the present invention.

[0054] Figure 4 This is a conceptual diagram for explaining the production method of the present invention.

[0055] Figure 5 It is a conceptual diagram for explaining an embodiment of the present invention.

[0056] Figure 6 It is a conceptual diagram for explaining an embodiment of the present invention. DETAILED DESCRIPTION

[0057] Hereinafter, a method for manufacturing a multilayer metasurface structure will be described in detail based on the preferred embodiment shown in the accompanying drawings.

[0058] In the present specification, a numerical range expressed using "to" means a range including the numerical values ​​described before and after "to" as the lower limit and the upper limit.

[0059] In this specification, “same” includes an error range generally allowed in the technical field.

[0060] The following figures are all conceptual diagrams for explaining the multi-layer metasurface structure. Therefore, the shape, size, thickness, spacing, and positional relationships of each component and the position of each layer in the plane direction may not be consistent with the actual ones.

[0061] Figure 1 An example of a multilayer metasurface structure is conceptually shown in FIG.

[0062] Figure 1 The multilayer metasurface structure 10 shown has a first substrate 12 , a second substrate 14 , a first structure layer 16 , a second structure layer 18 , a third structure layer 20 , a fourth structure layer 24 , and a spacer 26 disposed between the first substrate 12 and the second substrate 14 .

[0063] also, Figure 1 ( Figure 2-Figure 3 ) conceptually shows a cut in the multilayer supersurface structure along the thickness direction, i.e., consistent with the stacking direction of the first structure layer 16 to the fourth structure layer 24 and along the length direction of the first metal microstructure 16a to the fourth metal microstructure 24a described later, but in order to clearly show the structure of the multilayer supersurface structure, the hatching is omitted.

[0064] The first structure layer 16 is formed using one surface (upper surface in the figure) of the first substrate 12 , and is formed by arranging (arranging) a plurality of first metal microstructures 16 a on the surface of the first substrate 12 .

[0065] The second structure layer 18 is formed using one surface (lower surface in the figure) of the second substrate 14 , and a plurality of second metal microstructures 18 a are arranged (disposed) on the surface of the first substrate 12 .

[0066] The third structure layer 20 is formed using the other surface (the lower surface in the figure) of the first substrate 12 , and a plurality of third metal microstructures 20 a are arranged (arranged) on the surface of the first substrate 12 .

[0067] The fourth structure layer 24 is formed using the other surface (upper surface in the figure) of the second substrate 14 , and is formed by arranging (arranging) a plurality of fourth metal microstructures 24 a on the surface of the second substrate 14 .

[0068] The first substrate 12 and the first structure layer 16 constitute the first super-surface structure of the present invention.

[0069] In addition, the second substrate 14 and the second structure layer 18 constitute the second super-surface structure in the present invention.

[0070] Furthermore, as a preferred embodiment, Figure 1 The multilayer super-surface structure 10 shown has a third super-surface structure composed of a first substrate 12 and a third structure layer 20 , and a fourth super-surface structure composed of a second substrate 14 and a fourth structure layer 24 .

[0071] In the present invention, the so-called metasurface refers to a surface of a dielectric film in which a plurality of metal microstructures smaller than the optical wavelength corresponding to the design frequency, i.e., the corresponding electromagnetic wave frequency, are arranged and the macroscopic response to the incident electromagnetic wave is utilized.

[0072] The so-called first substrate 12 and second substrate 14 refer to the first structure layer 16 and the second structure layer 18 facing each other, sandwiching the spacer 26 and stacking and fixing. In the multilayer super surface structure 10 of the illustrated example, the first substrate 12 and the second substrate 14 are sandwiched by the spacer 26 and stacked, so that the first structure layer 16 and the second structure layer 18 are separated and stacked.

[0073] In addition, the first substrate 12 and the second substrate 14 are attached to each other via a spacer 26. This will be described in detail later.

[0074] In addition, the first structure body layer 16 and the third structure body layer 20 are stacked separately from each other via the first substrate 12 , and the second structure body layer 18 and the fourth structure body layer 24 are stacked separately from each other via the second substrate 14 .

[0075] Furthermore, the multilayer supersurface structure shown in the example of the figure has four layers of structures, namely, the first structure layer 16 to the fourth structure layer 24 .

[0076] However, the multilayer super surface structure of the present invention only needs to have the first structure layer 16 and the second structure layer 18, and can be Figure 3 Although the structure shown has only two structural layers, it may have three structural layers, or further, it may have five or more structural layers.

[0077] It is preferred that at least one of the first substrate 12 and the second substrate 14 has a structural body layer on both surfaces, and it is more preferred that both the first substrate 12 and the second substrate 14 have a structural body layer on both surfaces as shown in the example shown in the figure.

[0078] The same applies to the multilayered supersurface structures having two to three or five or more structural layers in the following description.

[0079] As a preferred embodiment, the multilayer supersurface structure 10 manufactured by the manufacturing method of the present invention acts on electromagnetic waves with a frequency of 10 THz or less, that is, electromagnetic waves with a wavelength of 30 μm or more. That is, the design electromagnetic wave of the multilayer supersurface structure 10 is preferably 10 THz or less.

[0080] Specifically, the so-called multilayer metasurface structure that acts on electromagnetic waves with a frequency below 10 THz means that when an electromagnetic wave with a certain frequency below 10 THz is incident, it acts as a high refractive index body for the electromagnetic wave. In other words, it means that it acts as a structure that can obtain a high diffraction angle.

[0081] In addition, the frequency of the electromagnetic wave played by the multilayer metasurface structure 10 has no lower limit, but preferably, the multilayer metasurface structure 10 acts on the electromagnetic wave with a frequency of more than 10 GHz, that is, a wavelength of less than 30 mm. More preferably, the multilayer metasurface structure 10 acts on the electromagnetic wave with a frequency of more than 100 GHz, that is, a wavelength of less than 3 mm.

[0082] That is, it is preferable that the multilayer metasurface structure 10 acts on electromagnetic waves having a frequency of 10 GHz to 10 THz, that is, so-called terahertz waves (THz waves).

[0083] As described above, the multilayer supersurface structure 10 is formed by stacking a first substrate 12 and a second substrate 14 via a spacer 26, wherein the first substrate 12 has a first structural body layer 16 on one surface and a third structural body layer 20 on the other surface; the second substrate 14 has a second structural body layer 18 on one surface and a fourth structural body layer 24 on the other surface.

[0084] The spacer 26 is a pattern-shaped (not solid) spacer that separates and stacks the first substrate 12 and the second substrate 14. The pattern shape preferably satisfies the following requirements.

[0085] ·Not in contact with the second metal microstructure 18a

[0086] ·Not in contact with the first metal microstructure 16a

[0087] · Having a size that can ensure strength to support the first substrate 12 and the second substrate 14 separately

[0088] Specifically, the spacer 26 may be a frame-shaped spacer provided along the in-plane direction of the first substrate 12 and the second substrate 14 to surround the arrangement of the first metal microstructures 16a of the first structure layer 16 and the arrangement of the second metal microstructures 18a of the second structure layer 18.

[0089] Furthermore, when the spacer 26 is in a frame shape, a part thereof may be cut away.

[0090] For example, from the perspective of ensuring the strength for supporting the first substrate 12 and the second substrate 14 separately, it is preferred to arrange the spacer 26 in a region corresponding to more than 50% of the outer circumference of the frame that is arranged along the in-plane direction of the first substrate 12 and the second substrate 14 to surround the arrangement of the first metal microstructures 16a of the first structural layer 16 and the arrangement of the second metal microstructures 18a of the second structural layer 18. It is more preferred to arrange the spacer 26 in a region corresponding to more than 75% of the portion, and it is further preferred to arrange the spacer 26 in a region corresponding to more than 90% of the portion.

[0091] In the multilayer metasurface structure 10 , both the first substrate 12 and the second substrate 14 are substrates made of dielectrics.

[0092] That is, in the multilayer supersurface structure 10 shown in the figure, the first substrate 12 acts as a dielectric layer arranged between the first structure layer 16 and the third structure layer 20, and the second substrate 14 acts as a dielectric layer arranged between the second structure layer 18 and the fourth structure layer 24.

[0093] Furthermore, the spacer 26 forms an air layer that functions as a dielectric between the first structure layer 16 and the second structure layer 18 .

[0094] The multilayer supersurface structure 10 shown in the figure is not limited to the one formed by providing metal microstructures on both surfaces of a substrate, dividing the substrate and stacking two of them, and then stacking the first to fourth structure layers separately.

[0095] For example, a multilayer supersurface structure can also be formed by using four substrates, namely, a substrate having a first structural body layer on one surface, a substrate having a second structural body layer on one surface, a substrate having a third structural body layer on one surface, and a substrate having a fourth structural body layer on one surface, and stacking the four substrates relative to the substrates, thereby stacking the first structural body layer to the fourth structural body layer separately from each other.

[0096] Furthermore, another layer (for example, an adhesive layer) may be disposed between the first substrate 12 and the first structure layer 16 , between the first substrate 12 and the third structure layer 20 , between the second substrate 14 and the second structure layer 18 , and between the second substrate 14 and the fourth structure layer 24 .

[0097] The first substrate 12 and the second substrate 14 are dielectric resin films.

[0098] The dielectric resin film refers to one or more dielectric substrates that can be processed independently and on which a metal pattern can be formed. In addition, the dielectric substrate may have a single-layer structure or a laminated structure.

[0099] As preferred dielectric substrates, for example, there can be exemplified dielectric substrates formed from polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefins such as polyethylene (PE), polypropylene (PP), polystyrene, ethylene vinyl acetate (EVA), cycloolefin polymers (COP) and cycloolefin copolymers (COC), vinyl resins, polycarbonate (PC), polyamide, polyimide, acrylic resins, and triacetyl cellulose (TAC).

[0100] Among them, substrates composed of cycloolefin polymer (COP) and cycloolefin copolymer (COC) can be preferably used.

[0101] The thickness of the first substrate 12 and the second substrate 14 is not limited, and the thickness can be appropriately set according to the formation material, etc. to fully play a role as a dielectric and support the metal microstructure described later. The thickness of the first substrate 12 and the second substrate 14 is preferably 5 to 100 μm, more preferably 10 to 80 μm, and further preferably 15 to 50 μm.

[0102] In addition, the first substrate 12 and the second substrate 14 preferably have high transmittance to the target electromagnetic wave. Specifically, the transmittance of the target electromagnetic wave of the first substrate 12 and the second substrate 14 is preferably 75% or more, more preferably 85% or more, and further preferably 95% or more. There is no particular upper limit to the transmittance of electromagnetic waves, and it is usually less than 100%.

[0103] When the thickness of the first substrate 12 and the second substrate 14 is equal to or greater than a predetermined thickness, the handling properties are excellent.

[0104] In addition, when the thickness of the first substrate 12 and the second substrate 14 is equal to or less than a predetermined thickness and / or the transmittance is equal to or greater than a predetermined value, it is easy to function as a metamaterial.

[0105] Furthermore, the first substrate 12 and the second substrate 14 are generally formed of the same material, but may be formed of different materials.

[0106] Furthermore, the thicknesses of the first substrate 12 and the second substrate 14 are generally the same, but may be different.

[0107] As described above, the multilayer supersurface structure 10 is formed by laminating the first substrate 12 and the second substrate 14 via the spacer 26 .

[0108] In the example shown, the spacer 26 is formed in a pattern and is in a frame shape surrounding the arrangement of the first metal microstructures 16a of the first structure layer 16 and the arrangement of the second metal microstructures 18a of the second structure layer 18 along the in-plane direction of the first substrate 12 and the second substrate 14 as described above.

[0109] In addition, the spacer 26 is not limited to a pattern having a frame shape surrounding the arrangement of the first metal microstructures 16a and the second metal microstructures 18a, and various patterns corresponding to the arrangement of the metal microstructures can be used.

[0110] For example, there can be exemplified a pattern consisting of a rectangular frame and diagonal lines of the frame, a pattern consisting of a circular frame and lines crossing the circle in a diameter direction, and a pattern consisting of a rectangular frame and lines parallel to the frame.

[0111] However, when an attempt is made to arrange spacers in an arrangement of fine metal structures, there may be problems such as difficulty in patterning the spacers.

[0112] In consideration of this point, as shown in the example of the figure, it is preferable to use a spacer 26 having a frame-shaped pattern surrounding the arrangement of the first metal microstructures 16 a and the second metal microstructures 18 a .

[0113] The distance between the first substrate 12 and the second substrate 14 , that is, the thickness of the spacer 26 is not limited, and may be appropriately set so as to ensure an air layer of sufficient thickness required to function as a dielectric layer.

[0114] Here, when the thickness of the spacer 26 is sufficiently thinner than the wavelength of the target electromagnetic wave, the resonance structure may change and the resonance peak may be deformed due to the proximity (coupling) between the first metal microstructure 16a and the second metal microstructure 18a, but this effect can also be actively utilized. However, when the thickness of the spacer 26 is made thinner and the resonance generated by the proximity between the first metal microstructure 16a and the second metal microstructure 18a is utilized, it is necessary to avoid the influence of the transmitted electromagnetic wave due to the alignment error generated during the stacking.

[0115] On the contrary, the thickness of the spacer 26 can be set sufficiently to allow the resonance between the first metal microstructure 16a and the second metal microstructure 18a to be negligible and to avoid the influence of the alignment error generated during stacking on the transmitted electromagnetic wave.

[0116] The spacer 26 will be described in detail later. As described below, the spacer 26 contains at least a polymer (cured material) of a polymerizable compound.

[0117] As described above, in the multilayer supersurface structure 10, the first structure layer 16 is formed by separately arranging a plurality of first metal microstructures 16a on one surface (upper surface in the figure) of the first substrate 12. The first structure layer 16 is basically composed of an arrangement of unit cells formed by one first metal microstructure 16a and the space around the first metal microstructure 16a.

[0118] The second structural body layer 18 is formed by arranging a plurality of second metal microstructures 18a separately on one surface (lower surface in the figure) of the second substrate 14. The second structural body layer 18 is basically composed of an arrangement of unit cells formed by one second metal microstructure 18a and the space around the second metal microstructure 18a.

[0119] The third structure layer 20 is formed by arranging a plurality of third metal microstructures 20a separately on the other surface (lower surface in the figure) of the first substrate 12. The third structure layer 20 is basically composed of an arrangement of unit cells formed by one third metal microstructure 20a and the space around the third metal microstructure 20a.

[0120] The fourth structure layer 24 is formed by arranging a plurality of fourth metal microstructures 24a separately on the other surface (lower surface in the figure) of the second substrate 14. The fourth structure layer 24 is basically composed of an arrangement of unit cells formed by one fourth metal microstructure 24a and the space around the fourth metal microstructure 24a.

[0121] As described above, in the multilayer supersurface structure 10, the first structure layer 16 to the fourth structure layer 24 all utilize the surface of the corresponding substrate and have the same basic structure in which the first metal microstructure 16a to the fourth metal microstructure 24a are arranged on the surface.

[0122] Therefore, in the following description, the first to fourth structural body layers 16 to 24 are collectively referred to as structural body layers when there is no need to distinguish them. Similarly, the first to fourth metal microstructures 16a to 24a are collectively referred to as metal microstructures when there is no need to distinguish them.

[0123] In the multilayer metasurface structure 10 , the structure layer has the same structure as a common general metasurface structure (metamaterial) in which metal microstructures (unit cells) are arranged on one surface of a substrate.

[0124] Therefore, there are no restrictions on the shape of the metal microstructures, the arrangement of the metal microstructures, the intervals (pitch) between the metal microstructures, and the like.

[0125] In the multilayer supersurface structure 10 , the metal microstructure is made of metal.

[0126] As described above, the multilayer metasurface structure 10 preferably acts on electromagnetic waves with a frequency of 10 THz or less. Metals have high electrical conductivity and transmittance with respect to electromagnetic waves with a frequency of 10 THz or less.

[0127] Therefore, the multilayer metasurface structure 10 can effectively refract electromagnetic waves having a frequency of 10 THz or less by using a metal microstructure.

[0128] The metal microstructure may be formed of any material that contains a metal and resonates when a specific electromagnetic wave is incident thereon, and is not particularly limited. In addition to metal, the metal microstructure may also contain dielectrics, magnetic materials, etc. In addition, the metal microstructure may contain a conductive material such as a conductive polymer.

[0129] Preferred examples of the metal include gold, silver, platinum, copper, aluminum, and alloys containing one or more of these, and more preferred examples include silver and copper.

[0130] Likewise, the shape of the metal microstructure constituting the structure layer is not limited, and various shapes used as metal microstructures (resonators) in known super-surface structures can be adopted.

[0131] The metal microstructure preferably has a structure and properties that can simultaneously generate electric resonance and magnetic resonance by interacting with the electric field and magnetic field of the incident electromagnetic wave when an electromagnetic wave is incident, and can simultaneously control the effective dielectric constant or magnetic permeability.

[0132] As the shape of the metal microstructure, for example, there can be exemplified metal wires, crosses such as metal wires crossed, hook crosses, C shapes, U shapes, double rings, V shapes, L shapes, H shapes, lattice shapes, spiral shapes, square shapes, and circular shapes. In addition, there can be used shapes such as "Appl. Sci. 2018, 8(9), 1689; https: / / doi.org / 10.3390 / app8091689" Figure 5 The bottom shape shown is three-dimensional, etc.

[0133] Among them, metal wires (metal rod-shaped bodies) are preferably used.

[0134] The cross-sectional shape of the metal wire is not limited, and various columnar shapes such as quadrangular prism, triangular prism and cylindrical shape can be adopted. In the quadrangular prism, the cross section in the direction perpendicular to the length direction can adopt various shapes such as square, rectangle, parallelogram and trapezoid. In addition, similarly, in the triangular prism, various shapes such as equilateral triangle and isosceles triangle can be adopted, and in the cylindrical shape, not only circle but also ellipse can be adopted.

[0135] In one structural body layer, only one kind of metal fine structure body may be used, or two or more kinds of metal fine structure bodies may be used in combination.

[0136] Furthermore, the metal microstructures included in the respective structural layers may be the same as or different from each other.

[0137] In the multilayer metasurface structure 10, the size of the metal microstructure is not limited, and like the usual metasurface structure (metamaterial), it is smaller than the wavelength of the target electromagnetic wave, preferably smaller than 1.0 times the wavelength, and more preferably smaller than 0.5 times the wavelength.

[0138] For example, in the case of electromagnetic waves having a frequency of 0.1 to 10 THz (terahertz waves), the size (major axis) of the metal microstructure is preferably 1 to 3000 μm, more preferably 5 to 1000 μm.

[0139] Figure 1 The multilayer super-surface structure 10 shown is composed of a first metal microstructure 16a, a second metal microstructure 18a, a third metal microstructure 20a and a fourth metal microstructure 24a which are arranged in an offset manner in the in-plane direction of the first substrate 12 and the second substrate 14.

[0140] In other words, when the multilayer super-surface structure 10 is viewed from the normal direction of the substrate, the first metal microstructure 16a, the second metal microstructure 18a, the third metal microstructure 20a, and the fourth metal microstructure 24a do not completely overlap.

[0141] In addition, the so-called normal direction is the direction orthogonal to the main surface of the sheet-like object. In the multilayer supersurface structure 10, it is the thickness direction, that is, the stacking direction of the structural layer, that is, the stacking direction of the first substrate 12, the spacer 26 and the second substrate 14.

[0142] The main surface refers to the largest surface of the sheet-like object, usually both surfaces in the thickness direction.

[0143] The multilayer super surface structure manufactured by the manufacturing method of the present invention is not limited thereto. Figure 2 As conceptually shown, the first metal microstructure 16 a , the second metal microstructure 18 a , the third metal microstructure 20 a , and the fourth metal microstructure 24 a may be arranged to coincide with each other in the in-plane direction of the first substrate 12 and the second substrate 14 .

[0144] That is, when the multilayer super-surface structure is viewed from the normal direction of the substrate, the first metal microstructure 16a, the second metal microstructure 18a, the third metal microstructure 20a, and the fourth metal microstructure 24a can be completely overlapped.

[0145] Further, the multilayer super surface structure manufactured by the manufacturing method of the present invention is as follows Figure 3 As shown conceptually, only two structural body layers, namely the first structural body layer 16 and the second structural body layer 18 , may be provided.

[0146] The multilayer supersurface structure manufactured according to the manufacturing method of the present invention, i.e., the multilayer supersurface structure of the present invention, can be a structure that converges, diffuses, or refracts electromagnetic waves in one direction. In addition, the multilayer supersurface structure can be a transmission type or a reflection type, but is preferably a transmission type.

[0147] Therefore, the multilayer metasurface structure can be used for various known elements such as super lenses such as convex lenses and concave lenses, and deflection elements that bend electromagnetic waves.

[0148] Here, the multilayer super surface structure utilizes the characteristic optical response shown by the metal microstructure in the structure layer, sets a refractive index distribution structure in the structure layer, and makes it a sheet-like element by utilizing the refractive index distribution. Therefore, the multilayer super surface structure is preferably a sheet-like super lens such as a convex lens and a concave lens.

[0149] Hereinafter, a method for manufacturing the multilayer supersurface structure of the present invention for manufacturing such a multilayer supersurface structure will be described in detail.

[0150] Furthermore, the multilayer supersurface structure of the present invention is a multilayer supersurface structure produced by the production method of the present invention having steps 1 to 3 shown below.

[0151] like Figure 4 As conceptually shown in the upper part of , a first super surface structure is prepared, wherein a first structure layer 16 formed by arranging first metal microstructures 16a is provided on one surface of a first substrate 12. In addition, in this example, a third super surface structure is provided, wherein a third structure layer 20 formed by arranging third metal microstructures 20a is provided on the other surface of the first substrate 12.

[0152] Similarly, a second super surface structure is prepared, wherein a second structure layer 18 formed by arranging second metal microstructures 18a is provided on one surface of a second substrate 14. As described above, in this example, a fourth super surface structure is provided, wherein a fourth structure layer 24 formed by arranging fourth metal microstructures 24a is provided on the other surface of the second substrate 14.

[0153] In addition, how the multilayer metasurface structure responds to electromagnetic waves with frequencies below 10 THz can be set by appropriately selecting and combining the shape and forming materials of the metal microstructures in each structural layer, the arrangement of the metal microstructures, and the spacing between the metal microstructures.

[0154] In the multilayer supersurface structure, the metal microstructures used and the arrangement of the metal microstructures in each structure layer can be set by a known method to obtain the target characteristics of the multilayer supersurface structure.

[0155] As an example, if the metasurface structure is a sheet lens (convex lens), the arrangement density of the metal microstructure is gradually reduced from the center to the periphery so that the phase difference given to the transmitted electromagnetic wave gradually decreases from the center to the periphery.

[0156] For these designs, as an example, commercially available simulation software is used to calculate the amplitude and phase of the electromagnetic wave that passes through the metal microstructure used, and the arrangement of the metal microstructure is set to obtain the distribution of the target phase difference (phase modulation amount (refractive index)).

[0157] The method for forming the structure layer in which the metal microstructures are arranged is not limited, and various known production methods used in the production of super-surface structures can be adopted.

[0158] As an example, a structure layer may be formed by forming a metal layer on both surfaces (or one surface) of a substrate by a known film forming method such as sputtering, and arranging metal microstructures on the metal layer by photolithography.

[0159] In the method for manufacturing a multilayer super surface structure of the present invention, first, in step 1, as Figure 4 As conceptually shown in the middle section, on the first super-surface structure (i.e., the formation surface of the first structure layer 16 of the first substrate 12), a spacer portion 26a of the spacer 26 that becomes a frame-shaped spacer is formed in a pattern in a manner that surrounds the arrangement of the first metal microstructures 16a constituting the first structure layer 16 in the direction of the substrate surface.

[0160] Next, in step 2, if Figure 4 As conceptually shown in the lower part of , the spacer portion 26a is pasted to the second super surface structure, that is, the formation surface of the second structure layer 18 of the second substrate 14, to obtain a stacked body including the first super surface structure, the spacer portion 26a and the second super surface structure.

[0161] Here, the spacer portion 26a contains a polymerizable compound and has a certain degree of viscosity until it is polymerized in the subsequent step 3. Therefore, in step 2, even if the spacer portion 26a and the second super surface structure (i.e., the surface on which the second structure layer 18 of the second substrate 14 is formed) are stacked and pasted, the two can be easily peeled off and pasted again.

[0162] Moreover, in the manufacturing method of the present invention, since the spacer portion 26a is configured as a pattern, the first super surface structure and the second super surface structure are not completely pasted together. In the example of the figure, as a preferred embodiment, there is a frame-shaped pattern. Therefore, the peeling of the stacked and pasted spacer portion 26a and the second super surface structure becomes easier.

[0163] Furthermore, when step 3 described later is performed, the polymerizable compound in the spacer portion 26 a is polymerized, and the adhesion between the first super-surface structure and the second super-surface structure is improved.

[0164] Therefore, the method for manufacturing a stacked supersurface structure of the present invention can manufacture a stacked supersurface structure with high positional accuracy between supersurface structures.

[0165] As described above, a multilayer metasurface structure formed by stacking multiple layers of metasurface structures can impart a larger phase to an incident electromagnetic wave than a conventional single-layer metasurface structure.

[0166] Here, in order to obtain target performance in a multilayer metasurface structure, the metasurface structures need to be accurately positioned, stacked, and pasted.

[0167] However, the microstructures forming the supersurface structure are very small. For example, as described above, in the case of electromagnetic waves with a frequency of 0.1 to 10 THz, the size of the microstructure is exemplified as 1 to 3000 μm. Therefore, in order to stack the supersurface structures with a proper positional relationship, very high precision is required, and it is rare that the supersurface structures can be stacked with a proper positional relationship in one operation.

[0168] When stacking, if the positional relationship between the metasurface structures is not appropriate, the metasurface structures need to be peeled off, re-aligned, and stacked again.

[0169] However, in the manufacture of the multilayered supersurface structure in the past, the stacked supersurface structures are pasted together by an adhesive. Therefore, even if the positional relationship between the stacked supersurface structures is not appropriate, it is extremely difficult to peel off the stacked supersurface structures.

[0170] In contrast, in the manufacturing method of the present invention, as described above, even after the spacer portion 26a and the second supersurface structure are stacked to form a stack including the first supersurface structure, the spacer portion 26a and the second supersurface structure, the second supersurface structure can be easily peeled off.

[0171] Therefore, when stacking the spacer portion 26a and the second supersurface structure, even if the positional relationship between the first supersurface structure and the second supersurface structure is not appropriate, the second supersurface structure can be easily peeled off, and the spacer portion 26a and the second supersurface structure can be aligned and stacked again.

[0172] As a result, according to the manufacturing method of the present invention, the positions of the metasurface structures can be appropriately aligned, and a multilayered metasurface structure with excellent positional accuracy between the metasurface structures can be manufactured.

[0173] Hereinafter, the steps 1 to 3 of the production method of the present invention will be described in more detail.

[0174] Process 1 of the manufacturing method of the present invention is a process of arranging a spacer portion containing a polymerizable compound in a pattern on a first supersurface structure, wherein the first supersurface structure includes a first substrate and a first structural layer formed by arranging a plurality of first metal microstructures on at least one surface side of the first substrate and arranged along an in-plane direction.

[0175] The first super-surface structure including the first structure layer used in this process is as described above.

[0176] The spacer used in this process includes a polymerizable compound. As described above, since the spacer includes a polymerizable compound, a certain degree of adhesion is generated. In addition, during the polymerization treatment in process 3 described later, the polymerizable compound is polymerized, and the adhesion between the first super surface structure and the second super surface structure is improved.

[0177] The type of the polymerizable compound contained in the spacer portion is not particularly limited, and a known polymerizable compound can be used.

[0178] The polymerizable compound refers to a compound different from a resin described later.

[0179] The polymerizable group possessed by the polymerizable compound may be any group that participates in the polymerization reaction, and examples thereof include groups having ethylenically unsaturated groups such as vinyl, acryloyl, methacryloyl, styryl and maleimide groups; and groups having cationically polymerizable groups such as epoxy and oxetane groups.

[0180] Among them, as the polymerizable group, a group having an ethylenically unsaturated group is preferred, and an acryloyl group or a methacryloyl group is more preferred.

[0181] The polymerizable compound is preferably a compound having one or more ethylenically unsaturated groups, and more preferably a compound having two or more ethylenically unsaturated groups in the molecule.

[0182] The number of ethylenically unsaturated groups in the molecule of the ethylenically unsaturated compound is preferably 1 to 6, more preferably 1 to 3, further preferably 2 to 3, and particularly preferably 3, in terms of better polymerizability.

[0183] The polymerizable compound may have an alkyleneoxy group.

[0184] The alkyleneoxy group is preferably an ethyleneoxy group or a propyleneoxy group, and is more preferably an ethyleneoxy group because the effects of the present invention are more excellent. The number of alkyleneoxy groups in the polymerizable compound is preferably 2 to 30, more preferably 2 to 20, per molecule.

[0185] It is also preferable that the polymerizable compound contains a polymerizable compound X.

[0186] The polymerizable compound X is a bifunctional ethylenically unsaturated compound having one or more aromatic rings in the molecule among the above-mentioned polymerizable compounds.

[0187] Examples of the aromatic ring possessed by the polymerizable compound X include aromatic hydrocarbon rings such as a benzene ring, a naphthalene ring, and an anthracene ring; aromatic heterocyclic rings such as a thiophene ring, a furan ring, a pyrrole ring, an imidazole ring, a triazole ring, and a pyridine ring; and condensed rings thereof, preferably an aromatic hydrocarbon ring, more preferably a benzene ring. The aromatic rings may have a substituent.

[0188] The polymerizable compound X may have two or more aromatic rings.

[0189] The polymerizable compound X preferably has a bisphenol structure from the viewpoint of improving the resolution by suppressing the swelling of the photosensitive layer caused by the developer.

[0190] Examples of the bisphenol structure include a bisphenol A structure derived from bisphenol A (2,2-bis(4-hydroxyphenyl)propane), a bisphenol F structure derived from bisphenol F (2,2-bis(4-hydroxyphenyl)methane), and a bisphenol B structure derived from bisphenol B (2,2-bis(4-hydroxyphenyl)butane), and a bisphenol A structure is preferred.

[0191] Examples of the polymerizable compound X having a bisphenol structure include a compound having a bisphenol structure and two polymerizable groups (preferably (meth)acryloyl groups) bonded to both ends of the bisphenol structure.

[0192] The two ends of the bisphenol structure may be directly bonded to the two polymerizable groups, or may be bonded via one or more alkyleneoxy groups. The alkyleneoxy groups added to the two ends of the bisphenol structure are preferably ethyleneoxy groups or propyleneoxy groups, and more preferably ethyleneoxy groups. The number of alkyleneoxy groups (preferably ethyleneoxy groups) added to the bisphenol structure is preferably 2 to 30 per molecule, and more preferably 2 to 20.

[0193] Examples of the polymerizable compound include bifunctional ethylenically unsaturated compounds and trifunctional or higher-functional ethylenically unsaturated compounds having no aromatic ring.

[0194] Examples of the bifunctional ethylenically unsaturated compound having no aromatic ring include alkylene glycol di(meth)acrylate, polyalkylene glycol di(meth)acrylate, urethane di(meth)acrylate, and trimethylolpropane diacrylate.

[0195] The molecular weight of the polymerizable compound is preferably 200 to 3,000, more preferably 280 to 2,200, and even more preferably 300 to 2,200.

[0196] The content of the polymerizable group in the polymerizable compound is preferably 1.0 mmol / g or more, more preferably 2.0 mmol / g or more, and the upper limit is preferably 10.0 mmol / g or less.

[0197] When the spacer portion includes a plurality of polymerizable compounds, the content of the polymerizable groups included in all the polymerizable compounds is preferably in the above-described preferred embodiment.

[0198] The "content of polymerizable groups" refers to the equivalent weight (mol) of polymerizable groups contained per 1 g of the polymerizable compound.

[0199] The polymerizable compound may be used alone or in combination of two or more.

[0200] The content of the polymerizable compound is preferably 5 to 70% by mass, more preferably 10 to 60% by mass, based on the total mass of the spacer portion.

[0201] The spacer unit may contain other components in addition to the polymerizable compound.

[0202] As other components, resins can be mentioned.

[0203] As the resin, a (meth)acrylic resin is preferred.

[0204] The (meth)acrylic resin is a resin having a structural unit derived from a (meth)acrylic compound, and examples of the (meth)acrylic compound include (meth)acrylic acid, (meth)acrylic acid esters, (meth)acrylamide, and (meth)acrylonitrile. In the (meth)acrylic resin, the content of the structural unit derived from the (meth)acrylic compound is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more relative to the total structural units of the resin.

[0205] In addition, the (meth)acrylic resin, for example, also preferably contains: a structural unit having an aromatic ring structure (for example, a structural unit derived from styrene, and a structural unit derived from benzyl (meth)acrylate, etc.), a structural unit having an aliphatic hydrocarbon ring structure (for example, a structural unit having an aliphatic hydrocarbon ring structure such as a tricyclodecane ring, a cyclohexane ring, a cyclopentane ring, a norbornane ring, an isoborone ring, and a tetrahydrodicyclopentadiene ring), a structural unit having an acid group (as the acid group, a carboxyl group, a sulfone group, a phosphonic acid group, and a phosphoric acid group can be mentioned), and a structural unit having a reactive group (for example, a polymerizable group).

[0206] When the (meth)acrylic resin contains a structural unit having an aromatic ring structure, the content of the structural unit having an aromatic ring structure is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, based on the total structural units of the (meth)acrylic resin.

[0207] When the (meth)acrylic resin contains a structural unit having an acid group, the content of the structural unit having an acid group is preferably 5 to 50% by mass, more preferably 5 to 40% by mass, based on the total structural units of the (meth)acrylic resin.

[0208] When the (meth)acrylic resin contains a structural unit having a reactive group, the content of the structural unit having a reactive group is preferably 5 to 70% by mass, more preferably 10 to 50% by mass, based on the total structural units of the (meth)acrylic resin.

[0209] The weight average molecular weight of the resin is preferably 5,000 to 500,000, more preferably 10,000 to 100,000, and even more preferably 10,000 to 60,000.

[0210] The Tg of the resin is preferably 60 to 135°C, more preferably 70 to 120°C.

[0211] The resins may be used alone or in combination of two or more.

[0212] The content of the resin is preferably 10 to 85% by mass, more preferably 20 to 75% by mass, based on the total mass of the spacer portion.

[0213] The spacer portion may contain a surfactant, a polymerization initiator, a sensitizer, a color developer, a rust preventive, and the like as other components.

[0214] The thickness of the spacer portion is preferably 1 to 5000 μm, more preferably 10 to 1000 μm.

[0215] The spacer portion is configured in a pattern. The shape of the pattern is not particularly limited, and is configured to form the pattern of the above-mentioned spacer. For example, as described above, the spacer is configured to obtain a frame-shaped pattern surrounding the arrangement of the first metal microstructure and the second metal microstructure. That is, in step 1, a frame-shaped spacer portion can be configured on the first super-surface structure in a manner surrounding the arrangement of the first metal microstructure.

[0216] The melt viscosity of the spacer portion is not particularly limited, but is preferably 1.0×10 5 Pa·s or more, and the melt viscosity at 80°C is less than 1.0×10 5When the melt viscosity of the spacer portion satisfies the above characteristics, the second supersurface structure can be more easily peeled off after being attached to the spacer portion, and the productivity of the multilayer supersurface structure is improved.

[0217] The melt viscosity of the spacer portion at 23°C is preferably 1.0×10 10 Pa·s or less.

[0218] The melt viscosity of the spacer portion at 80°C is preferably 1.0×10 1 Pa·s or above.

[0219] The measurement of the melt viscosity ηc of the spacer portion at 23° C. and 80° C. was performed as follows.

[0220] After making a spacer part with a thickness of about 0.5 mm, a rheometer DHR-2 manufactured by TA Instruments (parallel plates and Peltier plates with a diameter of 20 mm (Gap: about 0.5 mm)) was used to measure the set temperature at 20-125°C, a heating rate of 5°C / min, a frequency of 1 Hz, and a strain of 0.5%. The melt viscosity at each temperature was calculated based on the measured values ​​at 23°C and 80°C.

[0221] The step of arranging the spacer parts in a pattern is not particularly limited, and a known method can be used.

[0222] Among them, as one of the preferred methods of process 1, it is preferred that process 1 comprises: process A, forming a photosensitive layer containing a polymerizable compound on a first supersurface structure, wherein the first supersurface structure includes a first substrate, and a first structural layer formed by configuring the first substrate and arranging a plurality of first metal microstructures along the in-plane direction; process B, exposing the photosensitive layer into a pattern; and process C, performing a development process on the exposed photosensitive layer to form a spacer portion.

[0223] In the above steps A to C, after forming the photosensitive layer on the first super-surface structure, unnecessary portions are removed to form patterned spacer portions.

[0224] Hereinafter, steps A to C will be described in detail.

[0225] In process A, there is no particular restriction on the method for forming the photosensitive layer, as long as a photosensitive layer containing a polymerizable compound can be formed on the first super surface structure, and a method using a transfer film and a method for applying a photosensitive composition can be cited. As a method using a transfer film, it is preferred to prepare a transfer film including a temporary support and a photosensitive layer, and to paste the transfer film on the first super surface structure in a manner that the photosensitive layer side in the transfer film is opposite to the first structural body layer. As a method for applying a photosensitive composition, it is a method for applying a photosensitive composition to the first structural body layer of the first super surface structure to form a photosensitive layer. Among them, it is preferably a method using a transfer film.

[0226] The temporary support contained in the transfer film is preferably a film, more preferably a resin film. Examples of the resin film include polyethylene terephthalate films (e.g., biaxially stretched polyethylene terephthalate films), polymethyl methacrylate films, cellulose triacetate films, polystyrene films, polyimide films, and polycarbonate films.

[0227] The thickness of the temporary support is preferably 5 μm or more, more preferably 6 μm or more, and the upper limit is preferably 200 μm or less, and from the viewpoint of easy handling and versatility, it is more preferably 150 μm or less, and further preferably 50 μm or less.

[0228] From the viewpoint of improving the adhesiveness between the temporary support and the photosensitive layer, the surface of the temporary support in contact with the photosensitive layer may be subjected to a surface modification treatment.

[0229] Examples of the surface modification treatment include treatment using UV irradiation, corona discharge, plasma, and the like.

[0230] The photosensitive layer preferably contains the above-mentioned polymerizable compound, and more preferably contains the above-mentioned polymerizable compound and a resin.

[0231] The content of the polymerizable compound is preferably 5 to 70% by mass, more preferably 15 to 60% by mass, based on the total mass of the photosensitive layer.

[0232] The content of the resin is preferably 10 to 85% by mass, more preferably 20 to 75% by mass, based on the total mass of the photosensitive layer.

[0233] The photosensitive layer may contain other components besides the polymerizable compound and the resin.

[0234] As other components, a polymerization initiator can be mentioned. As the polymerization initiator, a known polymerization initiator can be used according to the form of the polymerization reaction.

[0235] The polymerization initiator may be any of a radical polymerization initiator and a cationic polymerization initiator, and is preferably a radical polymerization initiator.

[0236] Examples of the radical polymerization initiator include a polymerization initiator having an oxime ester structure, a polymerization initiator having an α-aminoalkylphenone structure, a polymerization initiator having an α-hydroxyalkylphenone structure, a polymerization initiator having an acylphosphine oxide structure, and a polymerization initiator having an N-phenylglycine structure.

[0237] From the viewpoint of photosensitivity, visibility of the exposed area and the non-exposed area, and resolution, the radical polymerization initiator preferably contains at least one selected from the group consisting of 2,4,5-triarylimidazole dimers and derivatives thereof.

[0238] The content of the polymerization initiator is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, based on the total mass of the photosensitive layer.

[0239] In addition to the above-mentioned components, the photosensitive layer may further contain a polymerization inhibitor, a surfactant, a sensitizer, a color developer, a rust preventive, and the like.

[0240] The method of attaching the transfer film to the first metasurface structure is not particularly limited, but a method of thermal compression bonding using a roller or the like is preferred.

[0241] After the above step A, step B of exposing the photosensitive layer in a pattern is performed. The exposed portion of the photosensitive layer remains as a spacer portion as described below. In addition, during exposure, it is preferable to set the exposure conditions so that the polymerizable compound contained in the photosensitive layer partially remains after exposure.

[0242] As the exposure method, a known method can be used. For example, a method using a photomask can be mentioned. By arranging a photomask between the photosensitive layer and the exposure light source, the photosensitive layer can be pattern-exposed through the photomask.

[0243] Examples of the exposure light source include various lasers, light emitting diodes (LEDs), ultrahigh pressure mercury lamps, high pressure mercury lamps, and metal halide lamps.

[0244] The exposure dose is preferably 5 to 200 mJ / cm 2 , more preferably 10 to 200 mJ / cm 2 The exposure amount is determined by the light source illumination and the exposure time. The exposure amount can be measured using a known light meter.

[0245] In the above exposure, the photosensitive layer may be exposed using a direct writing device instead of a photomask.

[0246] After the above step B, step C is performed in which the exposed photosensitive layer is developed to form a spacer portion. By performing this step, the unexposed portion is removed and a patterned spacer portion is formed.

[0247] As a method for the development treatment, a known method using a developer can be used, for example, flooding development, spray development, spin coating development, and immersion development.

[0248] The developer is preferably an alkaline aqueous solution. Examples of the alkaline compound (a compound that dissolves in water and has a pH exceeding 7.0) contained in the alkaline aqueous solution include sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium hydrogen carbonate.

[0249] In addition, as another preferred method of process 1, process 1 is also preferably a process of stacking a patterned photosensitive layer containing a polymerizable compound on a first supersurface structure to form a spacer portion, wherein the first supersurface structure includes a first substrate, and a first structural layer arranged on the first substrate and formed by arranging a plurality of first metal microstructures along an in-plane direction.

[0250] In the above process, a patterned photosensitive layer containing a polymerizable compound is directly laminated on the first supersurface structure. The patterned photosensitive layer corresponds to the spacer portion.

[0251] As a step of the above process, a method using a transfer film is preferred, wherein the transfer film includes a temporary support and a patterned photosensitive layer containing a polymerizable compound disposed on the temporary support. That is, a method of preparing a transfer film including a temporary support and a patterned photosensitive layer containing a polymerizable compound, and pasting the transfer film on the first supersurface structure in a manner that the photosensitive layer side of the transfer film is opposite to the first structural body layer can be cited.

[0252] The structures of the temporary support and the photosensitive layer constituting the transfer film are as described above.

[0253] The method for forming the photosensitive layer containing a polymerizable compound in a pattern is not particularly limited, and an example thereof includes a method of cutting away unnecessary portions of the photosensitive layer of the transfer film.

[0254] In the above step, the method of attaching the transfer film to the first metasurface structure is not particularly limited, but a method of thermal compression bonding using a roller or the like is preferred.

[0255] In the manufacturing method of the present invention, after implementing the above-mentioned step 1, step 2 is implemented. In this step 2, the second supersurface structure and the spacer portion are pasted to obtain a stack including the first supersurface structure, the spacer portion and the second supersurface structure, wherein the second supersurface structure includes a second substrate, and a second structure layer arranged on at least one surface side of the second substrate and composed of multiple second metal microstructures arranged along the in-plane direction.

[0256] The method of attaching the spacer portion and the second metasurface structure is not particularly limited, and a known method may be used.

[0257] Furthermore, as described above, in the manufacturing method of the present invention, since the second super-surface structure can be easily peeled off after the spacer portion and the second super-surface structure are attached to each other, the second super-surface structure can be stacked on the spacer portion with excellent positional accuracy.

[0258] In the manufacturing method of the present invention, after the above-mentioned step 2 is performed, the step 3 of polymerizing the polymerizable compound is performed. That is, the step 3 is a step of curing the polymerizable compound. By performing this step, the polymerizable compound in the spacer portion is polymerized, and the adhesion between the first supersurface structure and the second supersurface structure is improved. By performing this step, for example, Figure 1 The spacer 26 described in .

[0259] The method for polymerizing the polymerizable compound is not particularly limited, and examples thereof include heat treatment and light irradiation treatment. From the viewpoint of polymerizability, heat treatment is preferred.

[0260] The conditions for the heat treatment are not particularly limited, and the optimal conditions are selected according to the type of polymerizable compound used. The heating temperature during the heat treatment is preferably 80 to 250° C., and more preferably 90 to 160° C. The heating time during the heat treatment is preferably 1 to 180 minutes, and more preferably 5 to 60 minutes.

[0261] Before or simultaneously with the heat treatment, the laminate may be subjected to an exposure treatment (hereinafter also referred to as post-exposure treatment) as necessary.

[0262] Examples of the exposure light source in the post-exposure process include various lasers, light emitting diodes (LEDs), ultra-high pressure mercury lamps, high pressure mercury lamps, and metal halide lamps.

[0263] The exposure amount in the post-exposure post-treatment is preferably 100 to 5000 mJ / cm 2 , more preferably 200 to 3000 mJ / cm 2 .

[0264] The above describes in detail the manufacturing method of the multilayer supersurface structure and the multilayer supersurface structure of the present invention, but it is obvious that the present invention is not limited to the above examples, and various improvements or changes can be made without departing from the main purpose of the present invention.

[0265] [Example]

[0266] Hereinafter, the features of the present invention will be described in further detail with reference to examples.

[0267] In addition, the embodiment shown below is an example of the present invention. Therefore, the present invention should not be limited to the specific examples shown below.

[0268] [Preparation of Composition and Transfer Film]

[0269] <Synthesis of Resin A1>

[0270] Propylene glycol monomethyl ether (67 g) was placed in a flask and heated to 90°C under a nitrogen stream. A solution obtained by dissolving styrene (47.7 g), methyl methacrylate (1.3 g), methacrylic acid (19 g) and polymerization initiator V-601 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (4 g) in propylene glycol monomethyl ether (33 g) was added dropwise to the solution over 3 hours. After the addition was completed, 1 g of V-601 was added three times at intervals of 1 hour. Then, the resulting reaction solution was allowed to react for a further 3 hours. After the reaction, the reaction solution was diluted with propylene glycol monomethyl ether acetate (33 g) and propylene glycol monomethyl ether (100 g). Under an air stream, the diluted reaction solution was heated to 100°C, and tetraethylammonium bromide (0.53 g) and p-methoxyphenol (0.26 g) were added. Glycidyl methacrylate (Blenmar G manufactured by NOF Corporation) (32 g) was added dropwise to the liquid over 20 minutes. The obtained reaction solution was reacted at 100°C for 7 hours and then diluted with propylene glycol monomethyl ether acetate to obtain a solution of Resin A1 having a solid content concentration of 30%. The residual monomer content measured by gas chromatography was less than 0.1% by mass relative to the polymer solid content in any monomer.

[0271] The same method was used to synthesize resins A2 to A3 shown in Table 1. The amount of residual monomers in each resin measured by gas chromatography was less than 0.1% by mass relative to the polymer solid content in any monomer.

[0272] Table 1 shows the amount of structural units, weight average molecular weight, double bond content, and glass transition temperature (Tg) of each synthesized resin.

[0273] In Table 1, the abbreviations are as follows.

[0274] St:Styrene

[0275] MMA: Structural unit derived from methyl methacrylate

[0276] MAA: Structural unit derived from methacrylic acid

[0277] GMA-MAA: A structural unit formed by adding glycidyl methacrylate to a structural unit derived from methacrylic acid

[0278] BzMA: Structural unit derived from benzyl methacrylate

[0279] [Table 1]

[0280]

[0281] Next, compositions 1 to 3 were prepared according to the compositions shown in Table 2. The numerical values ​​of the components described in Table 2 represent parts by mass.

[0282] The respective abbreviations shown in Table 2 are as follows.

[0283] (Polymerizable compound)

[0284] BPE-100: ethoxylated bisphenol A dimethacrylate, manufactured by Shin-Nakamura Chemical Industry Co., Ltd. (double bond content: 4.30 mmol / g)

[0285] ·M-270: Aronix M-270, polypropylene glycol diacrylate (n≈12), manufactured by Toagosei Co., Ltd. (double bond content: 2.50 mmol / g)

[0286] BPE-500: ethoxylated bisphenol A dimethacrylate, manufactured by Shin-Nakamura Chemical Industry Co., Ltd. (double bond content: 2.49 mmol / g)

[0287] (Photopolymerization Initiator)

[0288] B-IMD: 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer

[0289] (Sensitizer)

[0290] ·EAB-F: 4,4'-bis(diethylamino)benzophenone

[0291] (Inhibitor)

[0292] Phenothiazines

[0293] Phenidone: Phenidone 1% methyl ethyl ketone (MEK) solution

[0294] (Chain transfer agent)

[0295] Compound A: N-phenylcarbamoylmethyl-N-carboxymethylaniline (manufactured by Fuji Film Co., Ltd. Wako Pure Chemical Industries, Ltd.)

[0296] (Developer)

[0297] ·LCV: Colorless crystal violet: Made by Tokyo Chemical Industry Co., Ltd.

[0298] (Rust Inhibitor)

[0299] ·CBT-1: Carboxybenzotriazole, manufactured by Chengbei Chemical Co., Ltd.

[0300] (Surfactant)

[0301] ·F-552: Megafac F-552, manufactured by DIC Corporation

[0302] (Solvent)

[0303] MMPGAc: 1-methoxy-2-propyl acetate

[0304] MEK: Methyl Ethyl Ketone

[0305] MFG: Propylene glycol monomethyl ether

[0306] [Table 2]

[0307]

[0308] Next, a transfer film is prepared using the above composition.

[0309] The specific steps are as follows.

[0310] First, the composition 1 was applied to the surface of a temporary support (polyethylene terephthalate film (E5001, manufactured by Toyobo Co., Ltd.) with a thickness of 100 μm) using a rod coater to form a coating film so that the thickness after drying was about 20 μm. Next, the coating film was dried at 90° C. using an oven. This operation was repeated 5 times to prepare a film so that the total thickness of the photosensitive layer reached 100 μm, and then a polypropylene film (E-201F, manufactured by Prince F-Tex Co., Ltd.) was attached as a protective film to prepare a transfer film 1.

[0311] The transfer film 2 was prepared by the same procedure as above except that the composition 1 used was changed to the composition 2.

[0312] Furthermore, a transfer film 3 was prepared in the same manner as above except that the composition 1 used was changed to the composition 3 and the total thickness of the photosensitive layer was changed to 20 μm.

[0313] Furthermore, a transfer film 4 was prepared in the same manner as above except that the composition 1 used was changed to the composition 4 and the total thickness of the photosensitive layer was changed to 20 μm.

[0314] [Example 1]

[0315] <Fabrication of metasurface structures>

[0316] Cycloolefin polymer films (COP films) (40 μm thick) were prepared as the first substrate and the second substrate by the method described in Japanese Patent No. 4991170.

[0317] The first substrate was cut into a size of 10×10 cm, and the surface was ultrasonically cleaned (45 kHz). After that, the cut first substrate was placed inside the sputtering device. After the pressure inside the device was reduced, argon gas was introduced, and the target material was sputtered using copper. The sputtering conditions were set to Ar gas pressure: 2 mTorr (0.27 Pa), power supply: 3.3 W / cm 2 .

[0318] This sputtering was performed sequentially on each single surface of the first substrate, and a copper layer having a thickness of 100 nm was formed on both surfaces of the first substrate.

[0319] The negative resist layer-forming composition was applied to a temporary support (PET film, average thickness 30 μm, haze 0.19%) using a slit nozzle so that the dry film thickness was 3 μm and the coating width was 1 m.

[0320] In addition, as the above-mentioned composition for forming a negative-type photoresist layer, a composition for forming a negative-type photoresist layer 1B described in paragraph 0562 of Japanese Patent Application Laid-Open No. 2020-204757 was used.

[0321] The temporary support coated with the negative-type resist layer-forming composition was passed through a drying zone at 80° C. for 40 seconds, and then a protective film (polyethylene film, manufactured by Tredegar, OSM-N) was pressed to prepare a negative-type transfer material.

[0322] The manufactured negative transfer material sequentially comprises a temporary support, a negative photoresist layer and a protective film.

[0323] The produced negative transfer material was cut into a size of 9×9 cm, and the protective film was peeled off from the negative transfer material.

[0324] The first substrate and the negative transfer material are pasted so that the surface of the negative photoresist layer exposed by peeling off the protective film is in contact with the copper layer. The negative transfer material is pasted on both sides of the first substrate in turn for each single side to obtain a laminate. The pasting is performed under the conditions of a roller temperature of 100°C, a linear pressure of 1.0 MPa, and a linear speed of 4.0 m / min.

[0325] Next, a photomask having a pattern complementary to the metal microstructure (metal cutting line) was stacked on the temporary support side of the negative transfer material on both sides of the obtained stack. 2 The negative photoresist layer of the negative transfer material was exposed by irradiation with an ultra-high pressure mercury lamp (manufactured by Dainippon Scientific Research Co., Ltd., MAP-1200L, exposure main wavelength: 365 nm).

[0326] The pattern of the photomask is formed only in a 1×1 cm area in the center of the substrate surface. In addition, the patterns on both sides of the first substrate are different, with one side being designed to correspond to the pattern of the first structural layer described later, and the other side being designed to correspond to the pattern of the third structural layer described later.

[0327] The temporary supports of negative transfer materials on both sides were peeled off from the exposed laminated body. Then, the laminated body was spray developed for 30 seconds using a 1.0% sodium carbonate aqueous solution at a liquid temperature of 25° C. to form a photoresist pattern on the copper layers on both sides.

[0328] Next, the copper layer of the obtained laminate was etched for 30 seconds at 23° C. using a copper etching solution (Cu-02 manufactured by Kanto Chemical Co., Ltd.). Furthermore, the photoresist pattern was peeled off using propylene glycol monomethyl ether acetate.

[0329] As described above, a 1×1 cm area in the center of one side of the first substrate is formed. Figure 5 and Figure 6 The first metal microstructure (metal cutting line) conceptually shown in the figure, with a length L of 0.4 mm and a width W of 0.05 mm, is arranged in a grid with a spacing g in the length direction of 0.02 mm and a spacing y in the width direction of 0.09 mm, forming a first structure layer (first supersurface structure).

[0330] In addition, a third structure layer (third super surface structure) in which third metal microstructures are arranged in the same manner is formed on the other surface of the first substrate. The third structure layer is formed so that the offset a between the first metal microstructures and the third metal microstructures in the longitudinal direction is 0.28 mm.

[0331] Furthermore, in exactly the same manner as the formation of the first structure layer and the third structure layer, a second structure layer (second super-surface structure) and a fourth structure layer (fourth super-surface structure) are formed on the second substrate.

[0332] <Fabrication of spacer and multilayer metasurface structure>

[0333] Next, a 1×1 cm area was cut out from the transfer film 1 by die cutting.

[0334] Next, one side (the side on the first structure layer side) of the first substrate (COP film) on both sides of which the metal microstructures prepared as described above are formed and the side of the photosensitive layer exposed by peeling off the protective film from the transfer film 1 are pasted together so that they are in contact with each other to obtain a laminated body. At this time, the alignment is performed by visual observation so that the area where the first structure layer on the first substrate is located coincides with the area where the transfer film 1 is cut away. Through such steps, the spacer portion is configured to surround the area where the first structure layer on the first substrate is located.

[0335] The lamination was performed under the conditions of a roll temperature of 100° C., a linear pressure of 1.0 MPa, and a linear speed of 1.0 m / min.

[0336] Next, the photosensitive layer of the transfer film 1 of the obtained laminated body that is exposed by peeling off the temporary support and one side (the side on the second structure layer side) of another second substrate (COP film) with metal microstructures formed on both sides are pasted together. When pasting, the pasting or peeling is performed while observing with an optical microscope. After alignment, pasting is performed under the conditions of a roller temperature of 100°C, a linear pressure of 1.0MPa, and a linear speed of 1.0m / min so that the area where the second structure layer on the second substrate is located is consistent with the hollowed-out area of ​​the photosensitive layer, and the configuration of the metal microstructure is as follows. Figure 5 The position relationship shown.

[0337] Furthermore, during the alignment, the metal microstructure can be smoothly attached or peeled off while being observed with an optical microscope, and the metal microstructure can be attached to form a configuration as shown in FIG. Figure 5 The positional relationship shown in the figure is that the positional deviation of the metal microstructure from the design is within 10 μm, and the rotational deviation is within 3°.

[0338] Thereafter, the obtained stacked body was subjected to a heat treatment at 100° C. for 5 minutes to polymerize the polymerizable compound in the spacer portion, thereby producing a multilayered supersurface structure.

[0339] Furthermore, the second structure layer formed on the second substrate was stacked so that the offset amount b between the first metal microstructure and the second metal microstructure was 0.07 mm.

[0340] Thus, the Figure 5 The multilayer supersurface structure shown has four structural layers, namely the first structural layer to the fourth structural layer.

[0341] [Example 2]

[0342] In the same manner as in Example 1, a first substrate having a first structural body layer and a third structural body layer arranged thereon and a second substrate having a second structural body layer and a fourth structural body layer arranged thereon were prepared.

[0343] Next, one side of the first substrate on which the metal microstructures are formed on both sides (the surface on the first structure layer side) and the surface of the photosensitive layer exposed by peeling off the protective film of the transfer film 2 are attached together so that they are in contact with each other to obtain a laminate. Next, a mask is set on the temporary support of the obtained laminate to shield the 1×1 cm area where the first structure layer is formed and not to shield the other parts, and a 100 mJ / cm 2 The photosensitive layer was exposed to a pattern by irradiating an ultra-high pressure mercury lamp (exposure main wavelength: 365 nm). Then, the temporary support was peeled off, and the laminate was sprayed and developed for 30 seconds using a 1.0 mass % sodium carbonate aqueous solution at a liquid temperature of 25° C. to form a spacer portion. Through such a step, the spacer portion was configured to surround the area where the first structural body layer on the first substrate was located.

[0344] The spacer section contained a polymerizable compound. The content of the polymerizable compound in the spacer section was 10% by mass relative to the total mass of the spacer section.

[0345] Then, the spacer portion and one side (the side of the second structure layer) of another second substrate (COP film) having metal microstructures formed on both sides are pasted while being aligned visually so that the opening (1 cm×1 cm area) of the spacer portion coincides with the area where the second structure layer is located on the second substrate. When pasting, the pasting or peeling is performed while observing with an optical microscope. After alignment, pasting is performed under the conditions of a roller temperature of 100°C, a linear pressure of 1.0 MPa, and a linear speed of 1.0 m / min so that the area where the second structure layer is located on the second substrate coincides with the opening of the spacer portion, and the configuration of the metal microstructure becomes as follows. Figure 5 The position relationship shown.

[0346] Furthermore, during the alignment, the metal microstructure can be smoothly attached or peeled off while being observed with an optical microscope, and the metal microstructure can be attached to form a configuration as shown in FIG. Figure 5 The positional relationship shown in the figure is that the positional deviation of the metal microstructure from the design is within 10 μm, and the rotational deviation is within 3°.

[0347] Then, the obtained laminate was subjected to a heat treatment at 145° C. for 30 minutes to produce an ultra-surface laminate.

[0348] [Example 3]

[0349] Except that the transfer film 3 is used instead of the transfer film 1, the multilayer metasurface structure is manufactured according to the same steps as in Example 1.

[0350] In addition, when the second substrate is aligned, it can be smoothly attached or peeled off while observing with an optical microscope as in Example 1, and the configuration of the metal microstructure is as follows: Figure 5 The positional relationship shown in the figure is that the positional deviation of the metal microstructure from the design is within 10 μm, and the rotational deviation is within 3°.

[0351] [Example 4]

[0352] Except that the transfer film 4 is used instead of the transfer film 1, the multilayer metasurface structure is manufactured according to the same steps as in Example 1.

[0353] In addition, regarding the alignment of the second substrate, when peeling the second substrate from the spacer portion, a greater force was required than in Examples 1 to 3, and peeling noise was generated, so it was necessary to be more cautious. The position deviation of the metal microstructure from the design was within 10 μm, and the rotation deviation was within 3°.

[0354] [Comparative Example 1]

[0355] Except that the transfer film 1 is not cut out by die cutting, the same steps as in Example 1 are followed to attempt to produce a multilayer metasurface structure.

[0356] In Comparative Example 1, the photosensitive layer is disposed on the entire surface of the first substrate. When the second substrate is aligned while being attached or peeled off on the photosensitive layer as in Example 1, the second metal microstructure on the second substrate is damaged, and a multilayered supersurface structure cannot be produced.

[0357] The results of Examples 1 to 4 and Comparative Example 1 are summarized and shown below.

[0358] The column “spacer section” indicates the shape of the spacer section. “Pattern-like” means that the spacer section is arranged to surround the structural layer, and “solid-like” means that the spacer section is arranged on the entire surface of the substrate.

[0359] The "melt viscosity" column shows the melt viscosity characteristics of the spacer used in each example. "A" means that the melt viscosity of the spacer at 23°C is 1.0×10 5 Pa·s or more, and the melt viscosity at 80°C is less than 1.0×10 5 Pa·s, "B" means the case where the above-mentioned "A" requirement is not satisfied.

[0360] In addition, the measurement of the melt viscosity ηc of the spacer portion at 23° C. and 80° C. was performed as follows.

[0361] As a method for measuring the melt viscosity of the spacer portion in Examples 1, 3 and 4, first, the spacer portion is stacked and adjusted to have a thickness of about 0.5 mm to prepare an evaluation sample. Then, using a rheometer DHR-2 manufactured by TA Instruments (20 mmΦ parallel plates and Peltier plates (Gap: using about 0.5 mm)), measurements are performed at a set temperature of 20 to 125°C, a heating rate of 5°C / min, a frequency of 1 Hz, and a strain of 0.5%. The melt viscosity at each temperature is calculated based on the measured values ​​at 23°C and 80°C.

[0362] As a method for measuring the melt viscosity of the spacer portion in Example 2, the photosensitive layer in the transfer film 2 was laminated so as to have a thickness of about 0.5 mm, and the resulting laminate was subjected to a 100 mJ / cm 2 The evaluation sample was irradiated with an ultra-high pressure mercury lamp (exposure main wavelength: 365 nm) as an exposure amount equivalent to pattern exposure, and the obtained evaluation sample was measured using the rheometer DHR-2 (20 mm Φ parallel plate and Peltier plate (Gap: about 0.5 mm)) manufactured by TA Instruments.

[0363] [Table 3]

[0364] Table 3 Spacer Melt viscosity Evaluation when manufacturing multi-layered supersurface laminates Example 1 Pattern A The alignment can be done smoothly and the manufacturing is successful without any problems. Example 2 Pattern A The alignment can be done smoothly and the manufacturing is successful without any problems. Example 3 Pattern A The alignment can be done smoothly and the manufacturing is successful without any problems. Example 4 Pattern B Compared with Examples 1 to 3, alignment is time-consuming and laborious. Comparative Example 1 Solid A During alignment, the metal microstructure was damaged and failed to be manufactured.

[0365] From the above results, the effects of the present invention are obvious.

[0366] INDUSTRIAL APPLICABILITY The present invention can be suitably used in a communication system using a terahertz wave, and the like.

[0367] Explanation of symbols

[0368] 10 multi-layer metasurface structures

[0369] 12. First substrate

[0370] 14 Second substrate

[0371] 16 First structural layer

[0372] 16a First metal microstructure

[0373] 18 Second structural layer

[0374] 18a Second metal microstructure

[0375] 20Third structural layer

[0376] 20a Third metal microstructure

[0377] 24 Fourth structural layer

[0378] 24a Fourth Metal Microstructure

[0379] 26 Spacers

[0380] 26a Spacer section

Claims

1. A manufacturing method of a multi-layered metasurface structure, comprising: Step 1, disposing a spacer portion containing a polymerizable compound in a pattern on a first metasurface structure, the first metasurface structure including a first substrate, and a first structure layer provided on at least one surface side of the first substrate and having a plurality of first metal microstructures arranged in a plane direction; Step 2, bonding a second metasurface structure to the spacer portion to obtain a laminate including the first metasurface structure, the spacer portion, and the second metasurface structure, the second metasurface structure including a second substrate, and a second structure layer provided on at least one surface side of the second substrate and having a plurality of second metal microstructures arranged in a plane direction; and Step 3, polymerizing the polymerizable compound.

2. The manufacturing method of the multi-layered metasurface structure according to claim 1, wherein, Step 1 includes: Step A, forming a photosensitive layer containing a polymerizable compound on the first metasurface structure, the first metasurface structure including the first substrate, and a first structure layer provided on the first substrate and having a plurality of the first metal microstructures arranged in a plane direction; Step B, exposing the photosensitive layer into a pattern; and Step C, performing a development process on the exposed photosensitive layer to form the spacer portion.

3. The manufacturing method of the multi-layered metasurface structure according to claim 1, wherein, Step 1 is a step of laminating a photosensitive layer containing a polymerizable compound in a pattern on the first metasurface structure to form the spacer portion, the first metasurface structure including the first substrate, and a first structure layer provided on the first substrate and having a plurality of first metal microstructures arranged in a plane direction.

4. The manufacturing method of the multi-layered metasurface structure according to claim 1, wherein, The melt viscosity of the spacer part at 23 °C is 1.0×10 5 Pa·s or more, and the melt viscosity at 80 °C is less than 1.0×10 5 Pa·s.

5. A multi-layered metasurface structure, wherein, the multi-layered metasurface structure is manufactured by the manufacturing method of the multi-layered metasurface structure according to any one of claims 1 to 4.

6. The multi-layered metasurface structure according to claim 5, wherein, the multi-layered metasurface structure is a transmissive element.

7. The multi-layered metasurface structure according to claim 5, wherein, the multi-layered metasurface structure is a sheet-like metalens.

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