Atomic layer deposition method for manufacturing omnidirectional structural color multilayer structures

Abstract

A method for forming a multilayer structure that reflects omnidirectional structural colors by atomic layer deposition (ALD) includes: introducing at least one reflective core particle into a reaction chamber; and depositing a conformal dielectric layer encapsulating at least one reflective core particle using a dielectric layer ALD cycle. Subsequently, a conformal barrier layer encapsulating the conformal dielectric layer is deposited using a barrier layer ALD cycle, and a conformal absorber layer encapsulating the conformal barrier layer is deposited using an absorber layer ALD cycle.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a multilayer structure that reflects omnidirectional structural color (OSC), and particularly to a method for manufacturing a multilayer structure including a metal layer and a metal oxide layer that encapsulate at least one reflective core particle, wherein at least one of the metal layer and the metal oxide layer is deposited by atomic layer deposition (ALD), and a barrier layer is disposed between each adjacent metal layer and metal oxide layer.

Background Art

[0002] Fabricating an OSC multilayer structure can be a complex and costly process because it requires very precise control over the layer thickness and layer quality. Small variations in layer thickness and minor contamination of the layer material (i.e., including infiltration of material between adjacent layers) can affect the optical performance of the OSC multilayer structure.

[0003] However, conventional deposition methods used to form multilayer structures can vary in complexity and cost depending on the desired thickness of the layer and the material that makes up a given layer. Also, conventional deposition methods limit the size and shape of the substrate, or the direction of deposition, leaving uncoated or unevenly coated surfaces and edges of the substrate. Defects in the surfaces and edges of the substrate can lead to, for example, undesirable scattering or transmission losses.

[0004] It is known to use the ALD method to form an OSC multilayer structure. However, conventional ALD methods are for small-scale production and are therefore too expensive for manufacturing on a commercial scale.

Summary of the Invention

[0005] A first aspect of the present invention includes a method for forming a multilayer structure that reflects omnidirectional structural colors by atomic layer deposition (ALD), the method comprising: introducing at least one reflective core particle into a reaction chamber; depositing a conformal dielectric layer encapsulating at least one reflective core particle by a dielectric layer ALD cycle; depositing a conformal barrier layer encapsulating the conformal dielectric layer by a barrier layer ALD cycle; and depositing a conformal absorber layer encapsulating the conformal barrier layer by an absorber layer ALD cycle.

[0006] A second embodiment includes the method of the first embodiment, wherein at least one reflective core particle comprises a conformal protective layer encapsulating the at least one reflective core particle.

[0007] A third embodiment includes the method of the second embodiment, wherein a conformal protective layer is formed by ALD, CVD, or a wet chemical process.

[0008] A fourth embodiment includes any of the above embodiments, further comprising depositing a conformal outer protective layer enclosing a conformal absorbent layer in an outer protective layer ALD cycle.

[0009] A fifth aspect includes any method of the above aspects, further comprising depositing a second conformal barrier layer encapsulating a conformal absorber layer using a second barrier layer ALD cycle, and depositing a second conformal dielectric layer encapsulating the second conformal barrier layer using a second dielectric layer ALD cycle.

[0010] A sixth aspect includes the method of the fifth aspect, which comprises depositing a conformal outer protective layer enclosing a second conformal dielectric layer in an outer protective layer ALD cycle.

[0011] A seventh embodiment includes any method of the above embodiment, wherein the dielectric layer ALD cycle comprises, in order, supplying a first component selected from the group consisting of halides, alkyls, alkoxides, alkylamides and carbonyls of Ti, Zn, Zr, Hf, Fe, Al, Pb, Ga, In, Si, Mg, K and combinations thereof to the reaction chamber; purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof; supplying a second component selected from the group consisting of O2, O3, H2O, H2O2, As2O3, As2O5, H2S, S2, Br2, HF, NH4F, SF6 and combinations thereof to the reaction chamber; and purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof.

[0012] The eighth aspect includes any method of the above aspect, wherein the barrier layer ALD cycle includes, in order, supplying a first component selected from the group consisting of halides of Al, Si, Mg, K, Zn and combinations thereof, alkyl, alkoxide, alkylamide and carbonyl into the reaction chamber; purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof; supplying a second component selected from the group consisting of O2, O3, H2O, H2O2, Br2, HF, NH4F and combinations thereof into the reaction chamber; and purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof.

[0013] The ninth embodiment includes any method of the above embodiment, wherein the absorber layer ALD cycle includes, in order, supplying a first component selected from the group consisting of halides, alkyls, alkoxides, alkylamides and carbonyls of W, Cr, Ge, Ni, Pd, Ti, Si, V, Co, Mo, Nb and combinations thereof to the reaction chamber; purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof; supplying a second component selected from the group consisting of SiH4, Si2H6, BH3, B2H6, H2, N2, NH3, O2, O3, H2O, H2O2 and combinations thereof to the reaction chamber; and purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof.

[0014] A tenth aspect includes the method of the fourth aspect, wherein the outer protective layer ALD cycle comprises, in order, supplying a first component selected from the group consisting of halides of Al, Si, Mg, K, Zn and combinations thereof, alkyl, alkoxide, alkylamide and carbonyl into the reaction chamber; purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof; supplying a second component selected from the group consisting of O2, O3, H2O, H2O2, Br2, HF, NH4F and combinations thereof into the reaction chamber; purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof; supplying trimethylaluminum and water into the reaction chamber; and purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof.

[0015] An eleventh aspect includes a method of the fifth aspect, wherein the second barrier layer ALD cycle comprises, in order, supplying a first component selected from the group consisting of halides of Al, Si, Mg, K, Zn and combinations thereof, alkyl, alkoxide, alkylamide and carbonyl into the reaction chamber; purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof; supplying a second component selected from the group consisting of O2, O3, H2O, H2O2, Br2, HF, NH4F and combinations thereof into the reaction chamber; and purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof.

[0016] A twelfth aspect includes a method of the fifth aspect, wherein the second dielectric layer ALD cycle comprises, in order, supplying a first component selected from the group consisting of halides, alkyls, alkoxides, alkylamides and carbonyls of Ti, Zn, Zr, Hf, Fe, Al, Pb, Ga, In, Si, Mg, K and combinations thereof to the reaction chamber; purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof; supplying a second component selected from the group consisting of O2, O3, H2O, H2O2, As2O3, As2O5, H2S, S2, Br2, HF, NH4F, SF6 and combinations thereof to the reaction chamber; and purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof.

[0017] The thirteenth embodiment includes, individually, a method according to any of the above embodiments, in each of the dielectric layer ALD cycle, barrier layer ALD cycle, and absorber layer ALD cycle, wherein the reaction chamber has a pressure of 13 Pascals or more and 2666 Pascals or less, and a temperature of 60°C or more and 150°C or less.

[0018] A fourteenth aspect includes the method of the fifth aspect, wherein, in each of the second barrier layer ALD cycle and the second dielectric layer ALD cycle, the reaction chamber has a pressure of 13 Pascals or more and 2666 Pascals or less, and a temperature of 60°C or more and 150°C or less.

[0019] The 15th embodiment includes any method of the above embodiment, wherein at least one reflective core particle is selected from the group consisting of Au, Cu, Al, brass, bronze, TiN, Cr, stainless steel, alumina (Al2O3), silica (SiO2), bismuth oxychloride, glass material, mica, and combinations thereof.

[0020] The sixteenth embodiment includes any method of the above embodiment, wherein the conformal dielectric layer is selected from the group consisting of TiO2, ZnS, ZrO2, HfO2, Fe3O4, AlAs, Fe2O3, PbS, GaAs, InAs, SiO2, MgF2, KBr, ZnO, Al2O3 and combinations thereof, the conformal barrier layer is selected from the group consisting of Al2O3, SiO2, MgF2, KBr, ZnO and combinations thereof, and the conformal absorber layer is selected from the group consisting of W, Cr, Ge, Ni, stainless steel, Pd, Ti, Si, V, TiN, Co, Mo, Nb, ferric oxide and combinations thereof.

[0021] A 17th aspect includes the method of the fourth aspect, wherein the conformal outer protective layer is selected from the group consisting of SiO2, Al2O3, organosilanes, organic phosphines, phosphates, and combinations thereof.

[0022] The 18th embodiment includes the method of the fifth embodiment, wherein the second conformal barrier layer is selected from the group consisting of Al2O3, SiO2, MgF2, KBr, ZnO and combinations thereof, and the second conformal dielectric layer is selected from the group consisting of TiO2, ZnS, ZrO2, HfO2, Fe3O4, AlAs, Fe2O3, PbS, GaAs, InAs, SiO2, MgF2, KBr, ZnO, Al2O3 and combinations thereof.

[0023] A 19th aspect includes the method of the 6th aspect, wherein the conformal outer protective layer is selected from the group consisting of SiO2, Al2O3, organosilanes, organic phosphines, phosphates, and combinations thereof.

[0024] The 20th embodiment includes any of the above embodiments, wherein the conformal dielectric layer has a thickness of 5 nm to 500 nm, the conformal barrier layer has a thickness of 50 nm or less, and the conformal absorber layer has a thickness of 2 nm to 50 nm.

[0025] The 21st aspect includes the method of the fifth aspect, wherein the second conformal barrier layer has a thickness of 50 nm or less, and the second conformal dielectric layer has a thickness of 5 nm or more and 500 nm or less. [Brief explanation of the drawing]

[0026] [Figure 1] Figure 1 is a schematic cross-sectional view of a multilayer thin-film structure according to the embodiments disclosed and described herein.

[0027] [Figure 2] Figure 2 schematically shows a stirred reactor for carrying out the ALD process according to the embodiments disclosed and described herein.

[0028] [Figure 3A] Figure 3A shows a multilayer structure having a ZnS dielectric layer extending over an Al reflective core layer used in the design of a multilayer structure.

[0029] [Figure 3B] Figure 3B shows a multilayer structure having a Si semiconductor absorber layer extending over an Al reflective core layer used in the design of a multilayer structure.

[0030] [Figure 3C]Figure 3C shows a multilayer structure having an Fe2O3 dielectric layer extending over an Al reflective core layer used in the design of a multilayer structure according to one or more embodiments shown and described herein.

[0031] [Figure 4] Figure 4 shows the reflection characteristics of the multilayer structure shown in Figures 3A-3C in the Lab color space.

[0032] [Figure 5A] Figure 5A shows a graph of the chroma and hue values ​​as a function of the thickness of the ZnS dielectric layer of the multilayer structure shown in Figure 3A.

[0033] [Figure 5B] Figure 5B shows a graph of the chroma and hue values ​​as a function of the thickness of the Si semiconductor absorber layer of the multilayer structure shown in Figure 3B.

[0034] [Figure 5C] Figure 5C shows a graph of the saturation and hue values ​​as a function of the thickness of the Fe2O3 dielectric layer of the multilayer structure shown in Figure 3C.

[0035] [Figure 6] Figure 6 shows a multilayer structure in which a dielectric layer extends on a substrate layer and is exposed to electromagnetic radiation at an angle θ with respect to a direction perpendicular to the outer surface of the dielectric layer.

[0036] [Figure 7A] Figure 7A is a transmission electron microscope (TEM) image of a multilayer structure according to the embodiments disclosed and described herein, showing well-separated metal and metal oxide layers.

[0037] [Figure 7B] Figure 7B is a further enlarged TEM image of a multilayer structure having a protective layer and a barrier layer according to the embodiments disclosed and described herein.

[0038] [Figure 7C]Figure 7C is a TEM image in which elemental aluminum is highlighted to show a clearly distinguishable Al reflective core layer and a clearly distinguishable Al2O3 barrier layer.

[0039] [Figure 7D] Figure 7D is a TEM image in which elemental oxygen is highlighted to show clearly distinguishable SiO2 protective layer, clearly distinguishable TiO2 dielectric layer, and clearly distinguishable Al2O3 barrier layer.

[0040] [Figure 7E] Figure 7E is a TEM image in which elemental tungsten is highlighted to show a clearly distinguishable W absorber layer with a smooth surface and no W penetration into the adjacent TiO2 dielectric layer.

[0041] [Figure 7F] Figure 7F is a TEM image in which elemental titanium is highlighted to show a clearly distinguishable TiO2 dielectric layer having a smooth surface and no penetration of TiO2 into adjacent Al reflective core layers or W absorber layers.

[0042] [Figure 8B] Figure 8B is a further magnified TEM image of the multilayer structure, which includes a TiO2 dielectric layer encapsulating an Al reflective core layer.

[0043] [Figure 8C] Figure 8C is a TEM image of a multilayer structure that includes a TiO2 dielectric layer enclosing an Al reflective core layer and a W absorber layer enclosing the TiO2 dielectric layer, with no barrier layer between the W absorber layer and the TiO2 dielectric layer.

[0044] [Figure 8D] Figure 8D is a further magnified TEM image of a multilayer structure without a barrier layer, showing the region to be analyzed by energy-dispersive X-rays for elemental analysis.

[0045] [Figure 8E] Figure 8E is a TEM image of a multilayer structure without a barrier layer, with elemental aluminum highlighted.

[0046] [Figure 8F] Figure 8F is a TEM image of a multilayer structure without a barrier layer, with elemental oxygen highlighted.

[0047] [Figure 8G] Figure 8G is a TEM image of a multilayer structure without a barrier layer, with elemental tungsten highlighted, showing that tungsten is dispersed in the TiO2 layer.

[0048] [Figure 8H] Figure 8H is a TEM image of a multilayer structure without a barrier layer, with elemental carbon highlighted.

[0049] [Figure 8I] Figure 8I is a TEM image of a multilayer structure without a barrier layer, with elemental titanium highlighted.

[0050] [Figure 8A] Figure 8A is a TEM image of a multilayer structure including a TiO2 dielectric layer encapsulating an Al reflective core layer.

[0051] [Figure 9] Figure 9 is an image showing that a structure with a barrier layer has higher pigment chromaticity compared to an OSC multilayer structure without a barrier layer.

[0052] [Figure 10A] Figure 10A is a graph of reflectance against the wavelength of electromagnetic radiation, illustrating the effect of the thickness of the tungsten absorber layer.

[0053] [Figure 10B]Figure 10B is a graph of reflectance against the wavelength of electromagnetic radiation, illustrating the effect of the thickness of the TiO2 dielectric layer. [Modes for carrying out the invention]

[0054] This disclosure relates to atomic layer deposition (ALD) of multilayer structures comprising metals and metal oxides on a reflective substrate for optical applications. At least one of the metals and metal oxides is deposited by ALD, and barrier layers are placed between each adjacent metal layer and metal oxide layer.

[0055] It is known that omnidirectional structural color (OSC) multilayer structures can be formed by directly depositing metals or metal oxides onto reflective materials and other metal and / or metal oxide layers using the ALD method. However, ALD deposition is conventionally costly and time-consuming. In particular, conventionally used ALD methods are for small-scale production and are too expensive for commercial production. Furthermore, when attempts were made to increase production volume, cross-layer material infiltration was observed. Therefore, a method for forming OSC multilayer structures that enables conformal coating, ultrathin layer deposition with nanoscale precision, minimal cross-layer material infiltration, and reduced manufacturing time is desirable.

[0056] For example, because ALD deposits material at virtually the atomic level, depositing thick layers, such as those exceeding 500 nm in thickness, using the ALD process can take a long time. Therefore, ALD is typically unsuitable for depositing individual layers in multilayer structures. Due to cost and time constraints, ALD has traditionally been limited to depositing very thin layers.

[0057] Furthermore, when attempts were made to increase production volume, it was confirmed that a mixed layer was formed in which various metal layers and / or metal oxide layers overlapped with each other, potentially affecting the optical properties of the OSC multilayer structure. This overlap is thought to occur due to the high porosity of the dielectric layer. That is, when a metal absorber layer is deposited by ALD, the high porosity of the dielectric layer allows the metal to impregnate the pores of adjacent dielectric layers and overlap with the dielectric layer, resulting in a mixed layer of metal and metal oxide. This mixed layer can have a significant effect on the overall optical properties of the multilayer structure by reducing the reflection and transmission properties of the dielectric layer.

[0058] However, as mentioned above, fabricating OSC multilayer structures requires very strict control over layer thickness and quality, and even small variations in thickness and material can affect the optical performance of the OSC multilayer structure.

[0059] ALD is an excellent technique for directly depositing multiple layers with nanoscale thicknesses onto a reflective core layer. Furthermore, ALD can deposit layers that conform to the size and shape of the substrate on which the layers are deposited, resulting in the deposited layers encapsulating the substrate (i.e., present on all sides). In other words, the substrate and the resulting multilayer structure can have asymmetric and heterogeneous shapes.

[0060] Therefore, disclosed herein is an ALD method for forming a multilayer structure, in which the ALD process for coating each of the multiple layers of the multilayer structure can be carried out in the same chamber. This means that downtime for removing particles and loading them into separate chambers can be avoided. The process disclosed herein enables the safe and effective commercial-level upscaling of ALD processes, which were previously only performed on a bench scale where a few grams of material were produced.

[0061] Furthermore, the ALD method disclosed and described herein can be used not only to apply metal layers and metal oxide layers on other metal layers and metal oxide layers, but also to apply thin (nanoscale) metal layers and metal oxide layers on reflective substrates. In addition, a thin barrier layer can be deposited between adjacent metal layers and metal oxide layers. The barrier layer prevents metal from impregnating the pores of the dielectric layer and forming a mixed layer. Because the barrier layer sufficiently separates all adjacent metal layers and metal oxide layers, their optical properties can be well predicted by simulation. Furthermore, in embodiments, the barrier layer is a thin layer and is made from a material that does not affect the optical properties of the multilayer structure.

[0062] The multilayer structures produced by the methods disclosed herein can be used as pigments in compositions (e.g., paint compositions), continuous thin films on structures, etc.

[0063] The multilayer structures described herein can be used to reflect visible light wavelengths in all directions across a range of incident angles in the field of view.

[0064] Furthermore, in the embodiment, the OSC multilayer structure can reflect a single narrow band of electromagnetic radiation within the visible spectrum when exposed to broadband electromagnetic radiation. This single narrow band of visible light includes a single narrow band of color shift in visible light that is less than 30° when observed at an angle of 0° to 45° with respect to the direction perpendicular to the outer surface of the multilayer thin film, as measured in Lab color space. Such a hue shift is small or inconspicuous. For example, the embodiment of the multilayer structure 100 described above may have a hue shift of less than 30°, e.g., less than 25°, less than 20°, less than 15°, or less than 10° in Lab color space when observed at an angle of 0° to 45°.

[0065] It should be understood that the terms "electromagnetic waves," "electromagnetic radiation," and "light" used herein may interchangeably refer to various wavelengths of light incident on a multilayer thin-film structure, and that such light may have wavelengths in the ultraviolet (UV), infrared (IR), and visible regions of the electromagnetic spectrum.

[0066] As used herein, “substrate” refers to the core layer and core particles. It should be understood that the terms “substrate,” “core layer,” and “core particles” as used herein may interchangeably refer to the surface on which the layer material is deposited. The “substrate” may have any shape, including but not limited to flakes, spheres, ovals, etc.

[0067] As used herein, "absorbent layer" includes both metal absorbent layers and non-metal absorbent layers.

[0068] As used herein, "dielectric layer" includes metal oxide dielectric layers and non-metal oxide dielectric layers.

[0069] The multilayer structure will now be described. Referring to Figure 1, the multilayer structure 100 according to the embodiments disclosed and described herein comprises reflective core particles 110, a conformal protective layer 111 enclosing the reflective core particles 110, a conformal dielectric layer 120 enclosing the conformal protective layer 111, a conformal barrier layer 121 enclosing the conformal dielectric layer 120, a conformal absorber layer 130 enclosing the conformal barrier layer 121, a second conformal barrier layer 131 enclosing the conformal absorber layer 130, a second conformal dielectric layer 140 enclosing the second conformal barrier layer 131, and a conformal outer protective layer 141 enclosing the second conformal dielectric layer 140. Where used herein, "conformal" is used to indicate that a layer conforms to the size and shape of the layer upon which it is deposited, encapsulates the layer upon which it is deposited, and follows the contour of the layer upon which it is deposited. Figure 1 shows a rectangular structure, but this is for illustrative purposes only, and in many cases, multilayer structures have asymmetrical and non-uniform shapes. In embodiments, the multilayer structure may be spherical or oval.

[0070] In one or more embodiments, the multilayer structure 100 may include fewer layers than those shown in Figure 1. For example, in one embodiment, the multilayer structure 100 comprises a substrate 110, a first conformal protective layer 111 enclosing the substrate 110, a conformal dielectric layer 120 enclosing the first conformal protective layer 111, a conformal barrier layer 121 enclosing the conformal dielectric layer 120, a conformal absorber layer 130 enclosing the conformal barrier layer 121, a second conformal barrier layer 131 enclosing the conformal absorber layer 130, and a second conformal dielectric layer 140 enclosing the second conformal barrier layer 131.

[0071] In one or more embodiments, the multilayer structure 100 comprises a substrate 110, a conformal dielectric layer 120 enclosing the substrate 110, a conformal barrier layer 121 enclosing the conformal dielectric layer 120, a conformal absorber layer 130 enclosing the conformal barrier layer 121, a second conformal barrier layer 131 enclosing the conformal absorber layer 130, and a second conformal dielectric layer 140 enclosing the second conformal barrier layer 131. An optional conformal outer protective layer 141 may enclose the second conformal dielectric layer 140.

[0072] In this embodiment, the multilayer structure 100 comprises a substrate 110, a conformal dielectric layer 120 enclosing the substrate 110, a conformal barrier layer 121 enclosing the conformal dielectric layer 120, and a conformal absorber layer 130 enclosing the conformal barrier layer 121. An optional conformal outer protective layer may enclose the conformal absorber layer 130.

[0073] In one or more embodiments, the multilayer structure 100 comprises a substrate 110, a first conformal protective layer 111 enclosing the substrate 110, a conformal dielectric layer 120 enclosing the first conformal protective layer 111, a conformal barrier layer 121 enclosing the conformal dielectric layer 120, and a conformal absorber layer 130 enclosing the conformal barrier layer 121. The second conformal barrier layer may optionally enclose the conformal absorber layer 130.

[0074] It should be understood that embodiments may also include multilayer structures having a conformal absorber layer encapsulating a substrate and a conformal dielectric layer encapsulating the conformal absorber layer. This multilayer structure may further include an optional conformal protective layer disposed between the conformal absorber layer and the substrate, an optional barrier, an optional conformal barrier layer disposed between the conformal dielectric layer and the conformal absorber layer, and an optional outer protective layer encapsulating the conformal dielectric layer.

[0075] Herein, the ALD method for producing the multilayer structures disclosed herein is generally described. ALD of each layer (dielectric layer, barrier layer, absorber layer, protective layer, and outer protective layer) is carried out by coating the substrate with the corresponding precursor compound in a stirred reactor at a suitable temperature, usually in the range of 60°C to 150°C. The precursor is supplied in the gas phase, which may be a gas at ambient temperature or vaporized and transported by a carrier gas such as nitrogen and argon. It will be understood that the terms “precursor,” “precursor compound,” and “compound” as used herein may interchangeably refer to the various precursors supplied to form the dielectric layer, barrier layer, absorber layer, protective layer, and outer protective layer of the multilayer structure.

[0076] Referring here to Figure 2, a stirred reactor 600 for depositing layers by ALD according to one or more embodiments includes a reaction chamber 610 in which ALD is carried out. The reaction chamber 610 may be equipped with a heater (not shown). The reaction chamber 610 also includes an inlet for a first precursor gas 620, an inlet for a second precursor gas 622, and an inlet for a purge gas 624. In embodiments, a single inlet may be present in the chamber 610 for the first precursor gas 620, the second precursor gas 622, and the purge gas 624, and in other embodiments, two or three separate inlets may be present in the chamber 610 for the first precursor gas 620, the second precursor gas 622, and the purge gas 624. It should also be understood that additional inlets may be provided if two or more precursors are required. For clarity, Figure 5 shows an embodiment having three inlets for the first precursor gas 620, the second precursor gas 622, and the purge gas 624. The chamber 610 may include a gas outlet 630 for releasing gas from the chamber 610. According to one or more embodiments, the gas outlet 630 may include a pump (not shown) to facilitate the release of gas from the chamber 610, and the gas outlet 630 may include a filter 632 to prevent particles from passing through the gas outlet 630 and out of the chamber 610. An agitator 640 is also present in the chamber 610 to agitate the particles during the ALD process. A chamber vibrator 650 is used to vibrate the chamber 610 during the ALD process, which helps to ensure uniform deposition.

[0077] During the ALD process, as further shown in Figure 2, multiple layers can be coated onto a substrate (such as multiple reflective core layers 110) within a stirred reactor 600. The substrate is introduced into a reaction chamber 610 and mixed by a stirrer 640. A chamber vibrator 650 can be used to avoid powder agglomeration and to improve the homogeneity of the coating. This means that a large flow of fluidizing gas is not required for this type of stirred reactor. To perform ALD for each layer (e.g., a conformal dielectric layer 120 and a conformal metal absorber layer 130), the previously deposited layer (or substrate) is coated with the corresponding precursor at the deposition temperature. In this embodiment, the deposition temperature is 60°C to 150°C, for example, 80°C to 150°C, 90°C to 150°C, 100°C to 150°C, 110°C to 150°C, 120°C to 150°C, 130°C to 150°C, 60°C to 130°C, 80°C to 130°C, 90°C to 130°C, 100°C to 130°C, 110°C to 130°C, 120°C to 130°C, and 60°C. The temperature ranges are above 120°C, 80°C to 120°C, 90°C to 120°C, 100°C to 120°C, 110°C to 120°C, 60°C to 110°C, 80°C to 110°C, 90°C to 110°C, 100°C to 110°C, 60°C to 100°C, 80°C to 100°C, 90°C to 100°C, 60°C to 90°C, 80°C to 90°C, or 60°C to 80°C. The precursor may be supplied in the gas phase, or it may be vaporized and transported by a carrier gas such as nitrogen and argon.

[0078] According to the embodiments, the dielectric layer and barrier layer are deposited by a reaction between a metal-containing compound and an oxygen-containing material. In the embodiments, examples of metal-containing compounds include halides, alkyls, alkoxides, alkylamides, and carbonyls. For example, titanium tetrachloride (TiCl4) may be selected as the precursor according to the embodiments to form a conformal dielectric layer of TiO2 on a substrate, and trimethylaluminum (TMA) may be selected as the precursor according to the embodiments to form a conformal barrier layer of Al2O3. In the embodiments, examples of oxygen-containing materials include oxygen (O2), ozone (O3), water (H2O), and hydrogen peroxide (H2O2). To improve the utilization of precursors, the metal-containing compound and the oxygen-containing compound are supplied in stoichiometric ratios as a first precursor, and the amount of the first precursor is estimated by the surface area of ​​the uncoated particles.

[0079] In one or more embodiments, a conformal metal absorber layer is deposited by a reaction between a metal-containing compound and one or more reducing agents. Examples of metal-containing compounds according to the embodiments include halides, alkyls, alkoxides, alkylamides, and carbonyls. For example, when depositing a W metal absorber, tungsten hexafluoride (WF6) is selected as the metal-containing compound. Examples of reducing agents in the embodiments include silane (SiH4), disilane (Si2H6), borane (BH3), diborane (B2H6), and hydrogen (H2). To improve the utilization of precursors, the metal-containing compound and the reducing agent are supplied in stoichiometric ratios as a second precursor, and the amount of the second precursor is estimated by the surface area of ​​the uncoated particles.

[0080] The following describes the process for forming a multilayer structure using the stirred reactor 600 shown in Figure 2.

[0081] In the first step, according to the embodiment, substrate particles such as reflective core layer particles are introduced into a stirred reactor 600, the chamber 610 is evacuated, and heated to a deposition temperature which is generally 60°C to 150°C, as disclosed above. This temperature is maintained for 1 to 4 hours, for example, 1 to 3 hours or 2 to 4 hours, to ensure that the temperature is stable.

[0082] In the second step, according to the embodiment, the first precursor gas 620 is introduced into the reaction chamber 610 through the inlet for a duration of 1 to 60 seconds. This administration step of the first precursor gas 620 is monitored by a pressure sensor. The substrate is mixed with the first precursor gas 620 at a target pressure for sufficient absorption of the first precursor gas 620 onto the active sites of the substrate.

[0083] In the third step, according to the embodiment, the chamber 610 is purged by introducing a purge gas 624 into the chamber 610 through the inlet to remove any excess first precursor and by-products present in the chamber 610 after the second step. The purge gas 624 is introduced into the chamber 610 for a duration of 1 to 60 seconds, and then the chamber 610 is evacuated. The purge gas 624 is a dry inert gas, such as nitrogen, argon, or a combination thereof. This third step can be repeated multiple times so that any excess first precursor does not affect the subsequent steps.

[0084] In the fourth step, according to the embodiment, the second precursor gas 622 is introduced into the chamber 610 through the inlet for a duration of 1 to 60 seconds. The administration step of the second precursor gas 622 is monitored by a pressure sensor. The substrate coated with a conformal dielectric layer is mixed with the second precursor at a target pressure for sufficient reaction between the metal-containing compound and the reducing agent of the second precursor gas 622.

[0085] In the fifth step, according to the embodiment, the chamber 610 is purged again by introducing purge gas 624 into the chamber 610 through the inlet to remove excess precursor and by-products introduced into the chamber 610 in the fourth step. The purge gas 624 is introduced into the chamber 610 for a duration of 1 to 60 seconds, and then the chamber 610 is evacuated. This step can be repeated multiple times so that excess precursor does not affect the next step.

[0086] In this embodiment, it should be understood that a metal absorber layer can be directly deposited on the substrate by introducing a second precursor gas in the second step, and a dielectric layer can be deposited on the absorber layer by introducing a first precursor in the fourth step.

[0087] In the second and fourth steps described above, each individual precursor administration step is monitored by a pressure sensor. The pressure inside the reaction chamber 610 is between 13 Pascals (Pa) and 2666 Pa, for example, 67 Pa to 2666 Pa, 133 Pa to 2666 Pa, 667 Pa to 2666 Pa, 1333 Pa to 2666 Pa, 2000 Pa to 2666 Pa, 13 Pa to 2333 Pa, 67 Pa to 2333 Pa, 133 Pa to 2333 Pa, 667 Pa to 2333 Pa, 1333 Pa to 2333 Pa, 2000 Pa to 2333 Pa, 13 Pa to 2000 Pa, 67 Pa to 2000 Pa, 133 Pa to 2000 Pa, 1333 Pa to 2000 Pa, 13 Pa to 1667 Pa, 67 Pa to 1667 Pa. The pressure can be between 133 Pa and 1667 Pa, between 667 Pa and 1667 Pa, between 1333 Pa and 1667 Pa, between 13 Pa and 1333 Pa, between 67 Pa and 1333 Pa, between 333 Pa and 1333 Pa, between 1000 Pa and 1333 Pa, between 13 Pa and 1000 Pa, between 67 Pa and 1000 Pa, between 333 Pa and 1000 Pa, between 667 Pa and 1000 Pa, between 13 Pa and 667 Pa, between 67 Pa and 667 Pa, between 133 Pa and 667 Pa, between 333 Pa and 667 Pa, between 13 Pa and 333 Pa, between 67 Pa and 333 Pa, between 133 Pa and 333 Pa, between 13 Pa and 133 Pa, between 67 Pa and 133 Pa, between 13 Pa and 67 Pa, etc.

[0088] The second through fifth steps of the ALD cycle may each be repeated until a desired layer thickness is achieved. For example, to form a thick dielectric layer, the second step may be repeated before moving to the third step, or the second and third steps may be repeated consecutively before moving to the fourth step. Similarly, to form a thick absorber layer, the fourth step may be repeated before moving to the fifth step, or the fourth and fifth steps may be repeated consecutively before moving. Using the above steps for the ALD process, each layer of a multilayer structure can be carried out in the same chamber in which the previous layer was deposited by ALD. Using the same chamber to deposit different layers reduces the downtime required in conventional processes where a first layer is deposited using a first precursor, and then a second chamber is loaded to deposit a second layer using a second precursor.

[0089] Next, we will further describe the details of the ALD method for manufacturing individual layers of a multilayer structure, including a dielectric layer, a barrier layer, an absorber layer, a protective layer, and an outer protective layer.

[0090] In embodiments, a method for forming a multilayer structure that reflects omnidirectional structural color by ALD includes: introducing at least one reflective core particle into a reaction chamber; depositing a conformal dielectric layer encapsulating the at least one reflective core particle by a dielectric layer ALD cycle; depositing a conformal barrier layer encapsulating the conformal dielectric layer by a barrier layer ALD cycle; and depositing a conformal absorber layer encapsulating the conformal barrier layer by an absorber layer ALD cycle. In embodiments, the at least one reflective core particle may include a conformal protective layer encapsulating the at least one reflective core particle. The conformal protective layer can be formed by ALD, CVD, or a wet chemical method in embodiments. The method may further include depositing a conformal outer protective layer encapsulating the conformal absorber layer by an outer protective layer ALD cycle.

[0091] In embodiments, the method may further include depositing a second conformal barrier layer enclosing a conformal absorber layer using a second barrier layer ALD cycle; and depositing a second conformal dielectric layer enclosing the second conformal barrier layer using a second dielectric layer ALD cycle. The method may further include depositing a conformal outer protective layer enclosing the second conformal dielectric layer using an outer protective layer ALD cycle.

[0092] Next, we will explain each of the above ALD cycles.

[0093] In the embodiment, the dielectric layer ALD cycle includes, in order, supplying a dielectric layer precursor containing two components to a reaction chamber. In the embodiment, the first component is selected from the group consisting of halides, alkyls, alkoxides, alkylamides, and carbonyls of Ti, Zn, Zr, Hf, Fe, Al, Pb, Ga, In, Si, Mg, K and combinations thereof. The reaction chamber is then purged with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof. A second component selected from the group consisting of O2, O3, H2O, H2O2, As2O3, As2O5, H2S, S2, Br2, HF, NH4F, SF6 and combinations thereof is introduced into the reaction chamber. Finally, the reaction chamber is purged with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof.

[0094] In the embodiment, the barrier layer ALD cycle includes, in order, supplying a barrier layer precursor containing two components to a reaction chamber. In the embodiment, the first component is selected from the group consisting of halides of Al, Si, Mg, K, Zn and combinations thereof, alkyl, alkoxide, alkylamide and carbonyl compounds. The reaction chamber is then purged with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof. A second component selected from the group consisting of O2, O3, H2O, H2O2, Br2, HF, NH4F and combinations thereof is introduced into the reaction chamber. Finally, the reaction chamber is purged with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof.

[0095] In the embodiment, the absorber layer ALD cycle includes, in order, supplying an absorber layer precursor containing two components to the reaction chamber. In the embodiment, the first component is selected from the group consisting of halides, alkyls, alkoxides, alkylamides, and carbonyls of W, Cr, Ge, Ni, Pd, Ti, Si, V, Co, Mo, Nb, and combinations thereof. The reaction chamber is then purged with a purge gas selected from the group consisting of nitrogen, argon, and combinations thereof. A second component selected from the group consisting of SiH4, Si2H6, BH3, B2H6, H2, N2, NH3, O2, O3, H2O, H2O2, and combinations thereof is introduced into the reaction chamber. Finally, the reaction chamber is purged with a purge gas selected from the group consisting of nitrogen, argon, and combinations thereof.

[0096] In the embodiment, the second barrier layer ALD cycle includes, in order, supplying a second barrier layer precursor containing two components to the reaction chamber. In the embodiment, the first component is selected from the group consisting of halides of Al, Si, Mg, K, Zn and combinations thereof, alkyl, alkoxide, alkylamide and carbonyl compounds. The reaction chamber is then purged with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof. A second component selected from the group consisting of O2, O3, H2O, H2O2, Br2, HF, NH4F and combinations thereof is introduced into the reaction chamber. Finally, the reaction chamber is purged with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof.

[0097] In the embodiment, the second dielectric layer ALD cycle includes, in order, supplying a second dielectric layer precursor containing two components to the reaction chamber. In the embodiment, the first component is selected from the group consisting of halides, alkyls, alkoxides, alkylamides, and carbonyls of Ti, Zn, Zr, Hf, Fe, Al, Pb, Ga, In, Si, Mg, K and combinations thereof. The reaction chamber is then purged with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof. A second component selected from the group consisting of O2, O3, H2O, H2O2, As2O3, As2O5, H2S, S2, Br2, HF, NH4F, SF6 and combinations thereof is introduced into the reaction chamber. Finally, the reaction chamber is purged with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof.

[0098] In the embodiment, the outer protective layer ALD cycle includes, in order, supplying an outer protective layer precursor comprising two components to the reaction chamber. In the embodiment, the first component is selected from the group consisting of halides of Al, Si, Mg, K, Zn and combinations thereof, alkyl, alkoxide, alkylamide and carbonyl. The reaction chamber is then purged with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof. A second component selected from the group consisting of O2, O3, H2O, H2O2, Br2, HF, NH4F and combinations thereof is introduced into the reaction chamber. Finally, the reaction chamber is purged with a purge gas selected from the group consisting of nitrogen, argon and combinations thereof.

[0099] The multilayer structure is coated with an outer protective layer of Al2O3. Here, trimethylaluminum (TMA) and water are used as precursors to form the protective layer in the reactor.

[0100] The following describes the multilayer structure formed using the ALD method described above.

[0101] In embodiments, at least one reflective core particle 110 may be made from at least one "gray metal" material, such as Al, Ag, Pt, Sn; at least one "colorful metal" material, such as Au, Cu, brass, bronze, TiN, Cr, stainless steel, or a combination thereof. In one or more embodiments, at least one reflective core particle 110 can be selected from the group consisting of Au, Cu, Al, brass, bronze, TiN, Cr, stainless steel, alumina (Al2O3), silica (SiO2), bismuth oxychloride, glass materials, mica, and combinations thereof. The substrate 110 may have a plate-like shape, or it may be spherical or oval-shaped, as described above.

[0102] In the embodiment, the conformal dielectric layer 120 can be selected from the group consisting of TiO2, ZnS, ZrO2, HfO2, Fe3O4, AlAs, Fe2O3, PbS, GaAs, InAs, SiO2, MgF2, KBr, ZnO, Al2O3, and combinations thereof. In the embodiment, the conformal dielectric layer 120 can be a high refractive index material, such as TiO2 existing in the rutile or anatase phase, or a low refractive index material, such as SiO2 or Fe2O3.

[0103] In the embodiment, the conformal absorber layer 130 can be selected from the group consisting of W, Cr, Ge, Ni, stainless steel, Pd, Ti, Si, V, TiN, Co, Mo, Nb, ferric oxide, and combinations thereof.

[0104] In the embodiment, the multilayer structure includes a protective layer 111 that encapsulates the substrate 110, and the conformal protective layer 111 can be a dense layer selected from the group consisting of SiO2, Al2O3, Fe2O3, and combinations thereof. Depending on the thickness and material of the protective layer, the protective layer 111 may be deposited by chemical vapor deposition (CVD), physical vapor deposition (PVD), or wet chemical deposition (WC).

[0105] In this embodiment, the multilayer structure further includes a conformal barrier layer 121 disposed between a conformal dielectric layer 120 and a conformal absorber layer 130, the conformal barrier layer 121 being selected from the group consisting of Al2O3, SiO2, MgF2, KBr, ZnO and combinations thereof.

[0106] In the embodiment, the multilayer structure may be encapsulated by an optional conformal outer protective layer that encloses the conformal absorbent layer 130, and the optional conformal outer protective layer can be selected from the group consisting of SiO2, Al2O3, organosilanes, organophosphines, phosphates, and combinations thereof.

[0107] Specifically, in the embodiment, the multilayer structure 100 may include at least one reflective core particle 110 containing Al, a conformal dielectric layer 120 containing TiO2 or Fe2O, a conformal barrier layer 121 containing Al2O3, and a conformal absorber layer 130 containing W.

[0108] Referring again to Figure 1, the multilayer structure 100 according to the embodiments disclosed and described herein comprises a substrate 110, a conformal dielectric layer 120 enclosing the substrate 110, a conformal absorber layer 130 enclosing the conformal dielectric layer 120, and a second conformal dielectric layer 140 enclosing the conformal absorber layer 130. The multilayer structure 100 disclosed and described herein consists of four “optical layers,” namely the substrate 110, the dielectric layer 120, the absorber layer 130, and the second dielectric layer. Since these four optical layers affect the optical system of the multilayer structure 100, the term “optical layer” as used herein does not include barrier layers, protective layers, and outer protective layers that do not affect the optical system of the multilayer structure.

[0109] In embodiments in which the multilayer structure 100 further comprises a second conformal dielectric layer 140, the second conformal dielectric layer 140 can be selected from the group consisting of TiO2, ZnS, ZrO2, HfO2, Fe3O4, AlAs, Fe2O3, PbS, GaAs, InAs, SiO2, MgF2, KBr, ZnO, Al2O3, and combinations thereof. In embodiments, the second conformal dielectric layer 140 can be a high refractive index material, such as TiO2 existing in the rutile or anatase phase, or a low refractive index material, such as SiO2 or Fe2O3.

[0110] In this embodiment, the multilayer structure further includes a second conformal barrier layer 131 disposed between a conformal absorber layer 130 and a second conformal dielectric layer 140, the second conformal barrier layer 131 being selected from the group consisting of Al2O3, SiO2, MgF2, KBr, ZnO, and combinations thereof.

[0111] In this embodiment, the multilayer structure may be encapsulated by a conformal outer protective layer 141 that encloses a second conformal dielectric layer 140, the conformal outer protective layer 141 being selected from the group consisting of SiO2, Al2O3, organosilanes, organic phosphines, phosphates, and combinations thereof.

[0112] Specifically, in the embodiment, the multilayer structure may include at least one reflective core particle 110 containing Al, a conformal protective layer 111 containing SiO2 or Al2O3, a conformal dielectric layer 120 containing TiO2 or Fe2O3, a conformal barrier layer 121 containing Al2O3, a conformal absorber layer 130 containing W, a second conformal barrier layer 131 containing SiO2 or Al2O3, and a second conformal dielectric layer 140 containing TiO2 or Fe2O3.

[0113] As described above, the thickness and material of the layers affect the optical properties of the OSC multilayer structure, and the ALD disclosed herein provides ultrathin layer deposition with nanoscale precision and minimal cross-layer material penetration. Next, the optical properties of the OSC multilayer structure will be described.

[0114] The optical system of an OSC multilayer structure is achieved by the optical layers of the multilayer structure. Referring again to Figure 1, the multilayer structure 100 according to the embodiments disclosed and described herein comprises a substrate 110, a conformal dielectric layer 120 enclosing the substrate 110, and a conformal absorber layer 130 enclosing the conformal dielectric layer 120. The multilayer structure 100 disclosed and described herein consists of three “optical layers,” namely the substrate 110, the dielectric layer 120, and the absorber layer 130. These three optical layers affect the optical system of the multilayer structure 100. The term “optical layer” as used herein does not include barrier layers, protective layers, and outer protective layers that do not affect the optical system of the multilayer structure.

[0115] Generally, the optical properties of multilayer structures, such as absorption and reflection wavelengths, saturation, and hue, depend on the architecture of the multilayer structure. Next, the effect of layer configuration on the saturation and hue of multilayer structures will be described. For example, Figures 3A to 3C and 4 show the simulated effectiveness of various multilayer structures in achieving a desired hue level in the red region of the visible light spectrum when plotted or displayed in Lab color space. As shown in Figures 3A to 3C, this simulation considers three simple multilayer structures, each having two optical layers, including a reflective core particle and a first layer which is a dielectric or absorber layer enclosing the reflective core particle. Figure 3A shows a ZnS dielectric layer 120a extending over the reflective core layer 110, Figure 3B shows a Si semiconductor absorber layer 120b extending over the reflective core layer 110, and Figure 3C shows an Fe2O3 absorber layer 120c extending over the reflective core layer 110. The reflectance simulations from each multilayer structure shown in Figures 2A to 2C were performed as functions of different thicknesses for the dielectric layer 120a, semiconductor absorber layer 120b, and absorber layer 120c.

[0116] Referring to Figure 4, the simulation results are a * b * The data is plotted in the Lab color space, also known as a color map. Each data point shown in Figure 4 represents the saturation and hue of a specific thickness of ZnS dielectric layer for the first multilayer structure, a specific thickness of Si semiconductor absorber layer for the second multilayer structure, or a specific thickness of Fe2O3 dielectric absorber layer for the third multilayer structure.

[0117] The saturation value provides the degree of brightness of a color, and the hue value provides the degree of color (e.g., red, green, blue, yellow, etc.) displayed by an object. Hue is a positive a of a given data point. * It is sometimes referred to as the angle relative to the axis. Saturation is a * b * In the Lab color space, also known as a color map, tan -1 (a * / b *) can be defined as. As shown in Figure 4, the multilayer structure shown in Figure 3A provides lower saturation compared to the multilayer structures shown in Figures 3B and 3C. Therefore, Figures 3A to 3C and 4 show that when high saturation is desired, an absorber layer (e.g., one absorber layer) is preferable to a dielectric layer as the first layer extending over the reflective core layer. The Lab color space analysis shown in Figure 4 is for illustrative purposes only, and it should be understood that the multilayer structures according to the embodiments disclosed and described herein may have different Lab color space values. For example, in the embodiments, the multilayer structure may exhibit blue, green, yellow, or other colors in the Lab color space.

[0118] Next, the effect of layer thickness on the saturation and hue of the three multilayer structures will be explained. Referring to Figures 5A to 5C, saturation and hue are shown as functions of layer thickness. Specifically, Figure 5A is a graph showing saturation and hue as functions of the thickness of the ZnS dielectric layer extending over the Al reflective core layer shown in Figure 3A. Figure 5B shows saturation and hue as functions of the thickness of the Si semiconductor absorber layer extending over the Al reflective core layer shown in Figure 3B. Figure 5C is a diagram showing saturation and hue as functions of the thickness of the FEZO absorber layer extending over the Al reflective core layer shown in Figure 5C. The dotted lines in Figures 5A to 5C correspond to desired hue values ​​of 10° to 30° in the Lab color space. Figures 5A to 5C show that for multilayer structures having an absorber layer extending across the reflective core layer, higher saturation values ​​can be achieved within the hue range of 10° to 30°. Again, the hues and saturations shown in Figures 5A to 5C are for illustrative purposes only, and it should be understood that the multilayer structures according to the embodiments disclosed and described herein may have different hue and saturation values.

[0119] Next, the effect of layer thickness on the absorption wavelength and reflection wavelength will be described. Assuming a multilayer structure including three optical layers as shown in FIG. 1, the conformal absorber layer 130 encapsulates the conformal dielectric layer 120, the conformal dielectric layer 120 encapsulates the reflective core particles 110, and the position of the conformal absorber layer is selected to increase the absorption of the target optical wavelength. For example, when the multilayer structure is configured to absorb electromagnetic radiation having a wavelength of 550 nm or less and reflect electromagnetic radiation having a wavelength of about 650 nm, such as visible light outside the hue of 10° to 30°, the absorber layer is arranged at a thickness where the electric field (|E| 2 ) is smaller at a wavelength of 550 nm than at a wavelength of 650 nm. Mathematically, this can be expressed as follows. [Equation] Preferably, it is as follows. [Equation]

[0120] FIG. 6 and the following discussion provide a method for calculating the thickness of a zero or near-zero electric field point at a given wavelength of light according to an embodiment. For the purposes of this specification, the term "near-zero" is defined as |E| 2 ≤ 10. FIG. 6 illustrates a multilayer structure having a dielectric layer 4 with an overall thickness "D", an incremental thickness "d", and a refractive index "n" on a substrate layer 2 having a refractive index "n s ". The substrate layer 2 can be the core layer, core particles, reflective core layer, or reflective core particles of the multilayer structure. The incident light hits the outer surface 5 of the dielectric layer 4 at an angle θ with respect to a line 6 perpendicular to the outer surface 5 and is reflected from the outer surface 5 at the same angle θ. The incident light passes through the outer surface 5 and enters the dielectric layer 4 at an angle θ F with respect to the line 6 and hits the surface 3 of the substrate layer 2 at an angle θ s . In the case of a single dielectric layer, θ s = θ FTherefore, the energy / electric field (E) can be expressed as E(z) when z=d. From Maxwell's equations, the electric field for s-polarized light is

number

number

[0121] It should be understood that the fluctuation of the electric field along the z-direction of the dielectric layer 4 can be estimated by calculating the unknown parameters u(z) and v(z), and here,

number

number

number

number

number

number

number

number

[0122] According to one or more embodiments, the conformal dielectric layer 120 has a wavelength of 5 nm to 500 nm, for example, 50 nm to 500 nm, 100 nm to 500 nm, 200 nm to 500 nm, 300 nm to 500 nm, 400 nm to 500 nm, 450 nm to 500 nm, 475 nm to 500 nm, 5 nm to 475 nm, 50 nm to 475 nm, 100 nm to 475 nm, 200 nm to 475 nm, 300 nm to 475 nm, 400 nm to 475 nm, 450 nm to 475 nm, 5 nm to 450 nm, 50 nm to 450 nm, 100 nm to 450 nm, 200 nm to 450 nm, 300 nm and above 450nm or less, 400nm to 450nm, 425nm to 450nm, 5nm to 400nm, 50nm to 400nm, 100nm to 400nm, 200nm to 400nm, 300nm to 400nm m or less, 350nm to 400nm, 5nm to 350nm, 50nm to 350nm, 100nm to 350nm, 200nm to 350nm, 300nm to 350nm, 325nm to 350nm, 5nm to 300nm, 50nm to 300nm, 100nm to 300nm, 200nm to 300nm, 250nm to 300nm, 5nm to 250nm, 50nm to 250nm, 100nm or more It can have thicknesses of 250 nm or less, 200 nm to 250 nm, 5 nm to 200 nm, 50 nm to 200 nm, 100 nm to 200 nm, 150 nm to 200 nm, 5 nm to 100 nm, 50 nm to 100 nm, 75 nm to 100 nm, 5 nm to 50 nm, 15 nm to 50 nm, 30 nm to 50 nm, 5 nm to 30 nm, 15 nm to 30 nm, or 5 nm to 15 nm.

[0123] In this embodiment, the conformal absorber layer 130 has a wavelength of 2 nm to 50 nm, for example, 2 nm to 45 nm, 2 nm to 40 nm, 2 nm to 35 nm, 2 nm to 30 nm, 2 nm to 25 nm, 2 nm to 20 nm, 5 nm to 20 nm, 8 nm to 20 nm, 10 nm to 20 nm, 12 nm to 20 nm, 15 nm to 20 nm, 18 nm to 20 nm, 2 nm to 18 nm, 5 nm to 18 nm, 8 nm to 18 nm, and 10 nm or more. It can have thicknesses such as 18nm or less, 12nm to 18nm, 15nm to 18nm, 2nm to 15nm, 5nm to 15nm, 8nm to 15nm, 10nm to 15nm, 12nm to 15nm, 2nm to 12nm, 5nm to 12nm, 8nm to 12nm, 10nm to 12nm, 2nm to 10nm, 5nm to 10nm, 8nm to 10nm, 2nm to 8nm, 5nm to 8nm, or 2nm to 5nm.

[0124] In this embodiment, the second conformal dielectric layer 140 has a wavelength of 5 nm to 500 nm, for example, 50 nm to 500 nm, 100 nm to 500 nm, 200 nm to 500 nm, 300 nm to 500 nm, 400 nm to 500 nm, 450 nm to 500 nm, 475 nm to 500 nm, 5 nm to 475 nm, 50 nm to 475 nm, 100 nm to 475 nm, 200 nm to 475 nm, 300 nm to 4 75nm or less, 400nm to 475nm, 450nm to 475nm, 5nm to 450nm, 50nm to 450nm, 100nm to 450nm, 200nm to 450nm, 300nm to 450nm Below, 400nm to 450nm, 425nm to 450nm, 5nm to 400nm, 50nm to 400nm, 100nm to 400nm, 200nm to 400nm, 300nm to 400nm, 35 0nm to 400nm, 5nm to 350nm, 50nm to 350nm, 100nm to 350nm, 200nm to 350nm, 300nm to 350nm, 325nm to 350nm, 5nm to 3 00nm or less, 50nm or more and 300nm or less, 100nm or more and 300nm or less, 200nm or more and 300nm or less, 250nm or more and 300nm or less, 5nm or more and 250nm or less, 50nm or more and 250nm or less, 100nm and 250nm or less It can have thicknesses such as 200nm to 250nm, 5nm to 200nm, 50nm to 200nm, 100nm to 200nm, 150nm to 200nm, 5nm to 100nm, 50nm to 100nm, 75nm to 100nm, 100nm or more, 5nm to 50nm, 15nm to 50nm, 30nm to 50nm, 5nm to 30nm, 15nm to 30nm, or 5nm to 15nm.

[0125] In this embodiment, the conformal barrier layer 121 can have a thickness of 50 nm or less, for example, 48 nm or less, 45 nm or less, 42 nm or less, 40 nm or less, 38 nm or less, 35 nm or less, 32 nm or less, 30 nm or less, 28 nm or less, 25 nm or less, 22 nm or less, 20 nm or less, 18 nm or less, 15 nm or less, 12 nm or less, 10 nm or less, 8 nm or less, 5 nm or less, or 2 nm or less.

[0126] In this embodiment, the second conformal barrier layer 131 can have a thickness of 50 nm or less, for example, 48 nm or less, 45 nm or less, 42 nm or less, 40 nm or less, 38 nm or less, 35 nm or less, 32 nm or less, 30 nm or less, 28 nm or less, 25 nm or less, 22 nm or less, 20 nm or less, 18 nm or less, 15 nm or less, 12 nm or less, 10 nm or less, 8 nm or less, 5 nm or less, or 2 nm or less.

[0127] According to one or more embodiments, the thickness of the outer protective layer 141 is 30 nm or less, for example, 25 nm or less, 20 nm or less, 15 nm or less, or 20 nm or less. In the embodiment, the thickness of the outer protective layer 141 is 5 nm or more and 15 nm or less, for example, 6 nm or more and 14 nm or less, 7 nm or more and 13 nm or less, or 8 nm or more and 12 nm or less.

[0128] The thickness of the protective layer 111 is, according to one or more embodiments, 3 nm to 15 nm, for example, 5 nm to 13 nm, 7 nm to 11 nm, or 8 nm to 10 nm.

[0129] As disclosed herein, the ALD process enables large-scale optically precise deposition of multiple layers with significant differences in material properties (e.g., dielectric materials versus metallic materials as described above). Furthermore, the ALD process makes it possible to fabricate multilayer structures with high density, low porosity, and complete layer coverage, all with nanometer-scale precision.

[0130] Thirteen points collected from P / P0 ≈ 0.06 to 0.3 were fitted to the Brunauer-Emmett-Teller (BET) equation to collect isotherms using nitrogen physicoadsorption at 76K, thereby obtaining the specific surface area (SSA) of the material. Further adsorption points were collected at various P / P0 values ​​up to P / P0 ≈ 0.95, and then desorbed down to P / P0 ≈ 0.06. The total pore volume was determined by the volume of nitrogen adsorbed at P / P0 approximately 0.95, and the average pore diameter was calculated using the Barrett-Joyner-Halenda (BJH) method.

[0131] In one or more embodiments, each of the conformal dielectric layer 120, conformal absorber layer 130, and second conformal dielectric layer 140 is individually 0.030 cm 3 Less than or equal to / g, for example, 0.025cm 3 / g or less, 0.020cm 3 / g or less, 0.015cm 3 / g or less, 0.010cm 3 / g or less, 0.009cm 3 / g or less, 0.008cm 3 / g or less, 0.007cm 3 / g or less, 0.006cm 3 / g or less, 0.005cm 3 / g or less, 0.004cm 3 / g or less, 0.003cm / g or less, 0.002cm 3 / g or less, 0.001cm 3 It has a pore volume that may be less than or equal to / g. In one embodiment, one or more of the conformal dielectric layer 120, conformal absorber layer 130, and second conformal dielectric layer 140 may have the same pore volume, and in another embodiment, one or more of the conformal dielectric layer 120, conformal absorber layer 130, and second conformal dielectric layer 140 may have different pore volumes.

[0132] In one or more embodiments, the surface area of ​​each of the conformal dielectric layer 120, conformal absorber layer 130, and second conformal dielectric layer 140 is, individually, 100 square meters / gram (m²). 2 ( / g) or less, for example, 90m 2 / g or less, 85m 2 / g or less, 80m 2 / g or less, 75m 2 / g or less, 70m 2 / g or less, 65m 2 / g or less, 60m 2 / g or less, 55m 2 / g or less, 50m 2 / g or less, 45m 2 / g or less, or 45m 2 / g or less, 40m 2 / g or less, 35m 2 / g or less, 30m 2 / g or less, 25m 2 / g or less, 20m 2 / g or less, 15m 2 / g or less, 10m 2 / g or less, 9m 2 / g or less, 8m 2 / g or less, 7m 2 / g or less, 6m 2 / g or less, 5m 2 / g or less, 4m 2 / g or less, 3m 2 / g or less, 2m 2 / g or less, or 1m 2 It is less than / g. Therefore, in this embodiment, each layer is 2m 2 / g or more 10m 2 / g or less, 3m 2 / g or more 10m 2 / g or less, 3m 2 / g or more 8m 2 / g or less, 5m 2 / g or more 8m 2 / g or less, 1m 2 / g or more 3m 2 / g or less, 3m 2 / g or more 5m 2 / g or less, 2m 2 / g or more 3m 2 / g or less, 1m 2 / g or more 2m2 Less than / g, or 0.5m 2 / g or more 1m 2 For example, less than or equal to / g. In one embodiment, one or more of the conformal dielectric layer 120, conformal absorber layer 130, and second conformal dielectric layer 140 may have the same surface area, while in another embodiment, one or more of the first conformal dielectric layer 120, conformal absorber layer 130, and second conformal dielectric layer 140 may have different surface areas.

[0133] In this embodiment, the multilayer structure is determined by the BET equation D 50 The amount of adsorbed gas that can have a diameter and form a single layer on the surface can be calculated from the measured isotherms. D measured by the BET equation 50 It can have a diameter. If we multiply the amount of molecules in this monolayer by the space required for one molecule, we get BET D 50 Given, BET D 50This includes particles between 1 μm and 500 μm, for example, 5 μm and 500 μm, 10 μm and 500 μm, 25 μm and 500 μm, 100 μm and 500 μm, 200 μm and 500 μm, 250 μm and 500 μm, 300 μm and 500 μm, 350 μm and 500 μm, 400 μm and 500 μm, 450 μm and 500 μm, 10 μm and 450 μm, 25 μm and 450 μm, 100 μm and 450 μm, 200 μm and 450 μm. 250μm to 450μm, 300μm to 450μm, 350μm to 450μm, 400μm to 450μm, 10μm to 400μm, 25μm to 400μm, 100μm to 400μm, 200μm to 40 0μm or less, 250μm or more and 400μm or less, 300μm or more and 400μm or less, 350μm or more and 400μm or less, 10μm or more and 350μm or less, 25μm or more and 350μm or less, 50μm or more and 350μm or less, 100μm or more and 350μm or less, 200μm m to 350 μm, 250 μm to 350 μm, 300 μm to 350 μm, 50 μm to 300 μm, 100 μm to 300 μm, 200 μm to 300 μm, 250 μm to 300 μm, 10 μm to 250 μm Bottom, 25 μm to 250 μm, 100 μm to 250 μm, 200 μm to 250 μm, 25 μm to 200 μm, 100 μm to 200 μm, 150 μm to 200 μm, 10 μm to 150 μm, 50 μm to 15 The particle size can be 0 μm or less, 100 μm to 150 μm, 1 μm to 100 μm, 5 μm to 100 μm, 10 μm to 100 μm, 25 μm to 100 μm, 50 μm to 100 μm, 1 μm to 50 μm, 5 μm to 50 μm, 10 μm to 50 μm, 25 μm to 50 μm, 1 μm to 25 μm, 5 μm to 25 μm, 10 μm to 25 μm, 1 μm to 10 μm, 5 μm to 10 μm, or 1 μm to 5 μm, etc.

[0134] The aspect ratios of the multilayer structures according to the embodiments disclosed and described herein, when measured by electron microscope (TEM, SEM) based on a number of flakes (both cross-section and surface are measured), are between 1 and 100, for example, 5 to 100, 10 to 100, 20 to 100, 30 to 100, 40 to 100, 50 to 100, 60 to 100, 70 to 100, 80 to 100, 90 to 100, 1 to 90, for example, 5 to 90, 10 to 90, 20 to 90, 30 to 90, 40 to 90, 50 to 90, 60 to 90, 70 to 90, 80 to 90, 1 to 80, 5 to 80, 10 to 80, 20 to 80, 30 to 80, 40 to 80, 50 to 80, 60 to 80, 70 to 80, 1 to 70, 5 to 70, 10 to 70, 20 to 70, 30 to 70, 40 to 70, 50 to 70 , 60 to 70, 1 to 60, 5 to 60, 10 to 60, 20 to 60, 30 to 60, 40 to 60, 50 to 60, 1 to 50, 5 to 50, It can be 10 to 50, 20 to 50, 30 to 50, 40 to 50, 1 to 40, 5 to 40, 10 to 40, 20 to 40, 30 to 40, 1 to 30, 5 to 30, 10 to 30, 20 to 30, 1 to 20, 5 to 20, 10 to 20, 1 to 10, 5 to 10, or 1 to 5, etc.

[0135] The multilayer structures in the embodiments disclosed herein can be used as pigments (e.g., paint pigments for paints used to coat objects) or as continuous thin films applied to objects. When used as pigments, at least one of paint binders and fillers can be used and mixed with the pigment to provide a paint exhibiting a highly saturated structural color. Furthermore, other additives may be added to the multilayer structures to aid in their suitability in the coating system. Exemplary suitability-enhancing additives include silane surface treatment agents that coat the exterior of the multilayer structure and improve its suitability in the coating system. Such coating systems or films can be used in any article, including automobiles. [Examples]

[0136] The embodiments will be further clarified by the following examples.

[0137] As mentioned above, mass production of ALDs can lead to overlaps between adjacent dielectric and absorber layers, which can result in degraded optical properties of multilayer structures. This overlap is thought to occur due to the high porosity of the dielectric layer (e.g., a TiO2 layer), which allows for overlap with the absorber layer (e.g., a W layer) applied by ALD, as the metal can be impregnated into the pores of the dielectric layer. Since all layers are sufficiently separated by a barrier or protective layer, their optical properties can be well predicted by simulation.

[0138] Example 1 A multilayer structure was formed using the ALD process. This multilayer structure included an aluminum reflective core layer, a conformal SiO2 primary protective layer encapsulating the reflective core layer, a conformal TiO2 dielectric layer encapsulating the conformal SiO2 protective layer, a conformal A2O3 barrier layer encapsulating the conformal TiO2 dielectric layer, and a conformal W absorber layer encapsulating the conformal A2O3 barrier layer.

[0139] Figure 7A is a TEM image of the as-formed multilayer structure. As shown in Figure 7A, each layer is clearly distinguishable, separated, and has a smooth surface. Figure 7B is a further magnified TEM image of the formed multilayer structure, further showing multiple clearly distinguishable, separated, and smooth layers. Figure 7C is a TEM image with elemental aluminum highlighted. Figure 7C shows that the Al reflective core layer 710 is very clearly distinguishable and has a smooth surface, and also shows a clearly distinguishable Al2O3 barrier layer 731. Both layers have smooth surfaces. Figure 7D is a TEM image with elemental oxygen highlighted. Figure 7D shows a clearly distinguishable SiO2 protective layer 711, a clearly distinguishable TiO2 dielectric layer 720, and a clearly distinguishable Al2O3 barrier layer 731, all of which have smooth surfaces and no significant overlap between the various oxygen-containing layers. Figure 7E is a TEM image with elemental tungsten highlighted. As shown in Figure 7E, the W absorber layer 730 is clearly distinguishable and has a smooth surface. Figure 7E also shows that there is no tungsten penetration into the TiO2 dielectric layer 720. Figure 7F is a TEM image with elemental titanium highlighted. Figure 7F shows a clearly distinguishable TiO2 dielectric layer 720 with a smooth surface, indicating that there is no TiO2 penetration into the Al reflective core layer 710 or the W absorber layer 730.

[0140] Comparative Example 1 A multilayer structure was formed using the ALD process. This multilayer structure included an aluminum reflective core layer, a conformal SiO2 protective layer encapsulating the reflective core layer, a conformal TiO2 dielectric layer encapsulating the conformal SiO2 protective layer, and a conformal W absorber layer encapsulating the conformal TiO2 dielectric layer. There was no barrier layer between the TiO2 dielectric layer and the W absorber layer.

[0141] Figure 8 shows the infiltration of tungsten from the metal layer into the adjacent porous TiO2 dielectric layer. Specifically, Figure 8A is a TEM image of the multilayer structure before the W absorber layer is deposited, and Figure 8B is a magnified TEM image of Figure 8A. In Figure 8B, the multilayer structure includes an aluminum reflective core layer, a conformal SiO2 protective layer encapsulating the reflective core layer, and a conformal TiO2 dielectric layer encapsulating the conformal SiO2 protective layer. As shown in Figure 8B, the conformal TiO2 dielectric layer appears porous. Figure 8C is a TEM image of the multilayer structure after the W absorber layer has been deposited. As shown in Figure 8C, tungsten from the W absorber layer has infiltrated into the TiO2 dielectric layer. Figure 8D is a further magnified TEM image of the multilayer structure, further showing the infiltration of W into the TiO2 dielectric layer. Figure 8E is a TEM image with elemental aluminum highlighted. Figure 8E shows that the Al reflective core layer 710 is very clearly distinguishable and has a smooth surface partially provided by the SiO2 protective layer. Figure 8F is a TEM image with elemental oxygen highlighted. Figure 8F shows that the oxygen concentration is higher at the bottom of the TiO2 dielectric layer (i.e., closer to the Al reflective core layer), and that only a small amount of tungsten was able to penetrate this area. Figure 8G is a TEM image with elemental tungsten highlighted. As shown in Figure 8G, there is no protective layer and W has penetrated into the TiO2. Figure 8H is a TEM image of a multilayer structure without a barrier layer, with elemental carbon highlighted. Carbon is the main component of the resin used to support the pigment. Figure 8I is a TEM image with elemental titanium highlighted. Figure 8I shows that the Ti concentration is higher at the bottom of the TiO2 dielectric layer (i.e., closer to the Al reflective core layer), and that only a small amount of tungsten was able to penetrate this area.

[0142] As shown in Example 1 and Comparative Example 1 above, Al2O is placed between the TiO2 dielectric layer and the W absorber layer. 23By depositing a barrier layer, the multilayer structure has clearly separated dielectric and absorber layers, resulting in a multilayer structure with improved chromaticity compared to a multilayer structure where no barrier layer exists between the TiO2 dielectric layer and the W absorber layer.

[0143] Example 2 Two coating systems were formed using the multilayer structures described in Example 1 and Comparative Example 1. Figure 9 compares the chromaticity of the two coating systems. Left side of Figure 9: A coating system formed using the multilayer structure described in Example 1. Right side of Figure 9: A coating system formed using the multilayer structure described in Comparative Example 1. Figure 9 shows that the coating system containing the multilayer structure described in Example 1 had a highly saturated blue color, while the coating system containing the multilayer structure described in Comparative Example 1 had a shifted blue hue and reduced saturation.

[0144] Example 3 The effects of the thickness of the tungsten absorber layer and the TiO2 dielectric layer were investigated in this example. Figures 10A and 10B show two sets of four multilayer structures containing three optical layers deposited using the ALD process. The three optical layers consisted of an Al reflective core layer, a TiO2 dielectric layer, and a W absorber layer.

[0145] Figure 10A shows one set of three-layer structures including W absorber layers with thicknesses of 5 nm, 7 nm, 9 nm, and 12 nm, and a TiO2 dielectric layer with a constant thickness of 50 nm. As shown in Figure 10A, as the thickness of the W absorber layer increased, the reflectance curve shifted slightly to lower wavelengths and became more reflective. Figure 10B shows one set of three-layer structures including a W absorber layer with a constant thickness of 5 nm, and TiO2 dielectric layers with thicknesses of 42 nm, 45 nm, 48 nm, and 50 nm. As shown in Figure 10B, as the thickness of the titanium dioxide layer increased, the reflectance curve shifted slightly to lower wavelengths.

[0146] Both sets of samples performed significantly better than the 7-layer structure formed by vacuum deposition.

[0147] Example 4 This example compares the density, surface area, and pore volume of multilayer structures fabricated using the ALD process and a wet chemical method. As shown in Table 1 below, the densities of the multilayer structures fabricated by the ALD method and the wet chemical method were the same, but the surface area of ​​the multilayer structure fabricated by the ALD method was much smaller.

[0148] [Table 1]

[0149] The density of a pigment is the ratio of the mass of the pigment sample to its volume, including the contribution of interparticle void volume. To measure this, a glass cylinder of a specific volume was used, and a known mass of pigment was introduced into the cylinder. The volume was estimated by adding deionized (DI) water to the cylinder until the water reached the cylinder's volume line. The volume of water was determined by measuring the mass of the amount of deionized water added. The sample volume was determined by subtracting the volume of water from the total volume of the cylinder. Repeated experiments were performed to determine the density. After degassing at 90°C for 1 hour, followed by degassing at 150°C for 3 hours, total adsorption / desorption isotherms were collected for the samples. Then, isotherms were collected using nitrogen physicoadsorption at 76K, and the specific surface area (SSA) of the material was obtained by fitting 13 points collected from P / P0 ≈ 0.06~0.3 to the Brunauer-Emmett-Teller (BET) equation. Further adsorption sites were collected at various P / P0 ratios up to P / P0 ≈ 0.95, followed by desorption down to P / P0 ≈ 0.06. The total pore volume was determined by the volume of nitrogen adsorbed at P / P0 ≈ 0.95, and the average pore diameter was calculated using the Barrett-Joyner-Halenda (BJH) method.

[0150] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Therefore, it is intended that such modifications and variations be covered, provided that they fall within the scope of the appended claims and equivalents thereof.

Claims

1. A method for forming a multilayer structure that reflects omnidirectional structural color by atomic layer deposition (ALD), Introducing at least one reflective core particle into the reaction chamber, Depositing a conformal dielectric layer containing at least one reflective core particle by a dielectric layer ALD cycle; Depositing a conformal barrier layer enclosing the conformal dielectric layer by a barrier layer ALD cycle; and A conformal absorber layer containing the conformal barrier layer is deposited using an absorber layer ALD cycle; A method that includes this.

2. The method according to claim 1, wherein the at least one reflective core particle comprises a conformal protective layer encapsulating the at least one reflective core particle.

3. The method according to claim 2, wherein the conformal protective layer is formed by ALD, CVD, or a wet chemical process.

4. The method according to claim 1, further comprising depositing a conformal outer protective layer enclosing the conformal absorber layer by an outer protective layer ALD cycle.

5. Depositing a second conformal barrier layer enclosing the conformal absorber layer by a second barrier layer ALD cycle; and A second conformal dielectric layer encapsulating the second conformal barrier layer is deposited using a second dielectric layer ALD cycle; The method according to claim 1, further comprising:

6. The method according to claim 5, further comprising depositing a conformal outer protective layer enclosing the second conformal dielectric layer in an outer protective layer ALD cycle.

7. The dielectric layer ALD cycle proceeds in order: A first component selected from the group consisting of Ti, Zn, Zr, Hf, Fe, Al, Pb, Ga, In, Si, Mg, K, and combinations thereof is supplied to the reaction chamber; Purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon, and combinations thereof; O ２ 、 O ３ 、 H ２ O、 H ２ O ２ 、 As ２ O ３ 、 AS ２ O ５ 、 H ２ S、 S ２ 、 Br ２ 、 HF、 NH ４ F、 SF ６ supplying to the reaction chamber a second component selected from the group consisting of these and combinations thereof; and Purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon, and combinations thereof; The method according to claim 1, including the method described in claim 1.

8. The barrier layer ALD cycle proceeds in order: A first component selected from the group consisting of halides of Al, Si, Mg, K, Zn and combinations thereof, alkyl, alkoxide, alkylamide and carbonyl compounds is supplied to the reaction chamber; Purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon, and combinations thereof; O ２ , O ３ , H ２ O, H ２ O ２ , Br ２ HF, NH ４ Supplying a second component selected from the group consisting of F and combinations thereof to the reaction chamber; and Purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon, and combinations thereof; The method according to claim 1, including the method described in claim 1.

9. The absorber layer ALD cycle proceeds in order: A first component selected from the group consisting of halides, alkyls, alkoxides, alkylamides, and carbonyls of W, Cr, Ge, Ni, Pd, Ti, Si, V, Co, Mo, Nb, and combinations thereof is supplied to the reaction chamber; Purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon, and combinations thereof; SiH ４ Si ２ H ６ BH ３ , B ２ H ６ , H ２ , N ２ NH ３ , O ２ , O ３ , H ２ O, H ２ O ２ Supplying a second component selected from the group consisting of and combinations thereof to the reaction chamber; and Purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon, and combinations thereof; The method according to claim 1, including the method described in claim 1.

10. The aforementioned external protective layer ALD cycle proceeds in order: A first component selected from the group consisting of halides of Al, Si, Mg, K, Zn and combinations thereof, alkyl, alkoxide, alkylamide and carbonyl compounds is supplied to the reaction chamber; Purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon, and combinations thereof; O ２ , O ３ , H ２ O, H ２ O ２ , Br ２ HF, NH ４ A second component selected from the group consisting of F and combinations thereof is supplied to the reaction chamber; Purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon, and combinations thereof; Supplying trimethylaluminum and water to the reaction chamber; and Purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon, and combinations thereof; The method according to claim 4, including the method described in claim 4.

11. The second barrier layer ALD cycle proceeds in order: A first component selected from the group consisting of halides of Al, Si, Mg, K, Zn and combinations thereof, alkyl, alkoxide, alkylamide and carbonyl compounds is supplied to the reaction chamber; Purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon, and combinations thereof; O ２ , O ３ , H ２ O, H ２ O ２ , Br ２ HF, NH ４ Supplying a second component selected from the group consisting of F and combinations thereof to the reaction chamber; and Purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon, and combinations thereof; The method according to claim 5, including the method described in claim 5.

12. The second dielectric layer ALD cycle proceeds in order: A first component selected from the group consisting of halides, alkyls, alkoxides, alkylamides, and carbonyls of Ti, Zn, Zr, Hf, Fe, Al, Pb, Ga, In, Si, Mg, K, and combinations thereof is supplied to the reaction chamber; Purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon, and combinations thereof; O ２ , O ３ , H ２ O, H ２ O ２ As ２ O ３ As ２ O ５ , H ２ S, S ２ , Br ２ HF, NH ４ F, SF ６ Supplying a second component selected from the group consisting of and combinations thereof to the reaction chamber; and Purging the reaction chamber with a purge gas selected from the group consisting of nitrogen, argon, and combinations thereof; The method according to claim 5, including the method described in claim 5.

13. The method according to claim 1, wherein, in each of the dielectric layer ALD cycle, the barrier layer ALD cycle, and the absorber layer ALD cycle, the reaction chamber has a pressure of 13 Pascals or more and 2666 Pascals or less, and a temperature of 60°C or more and 150°C or less.

14. The method according to claim 5, wherein, in each of the second barrier layer ALD cycle and the second dielectric layer ALD cycle, the reaction chamber has, individually, a pressure of 13 Pascals or more and 2666 Pascals or less, and a temperature of 60°C or more and 150°C or less.

15. The at least one reflective core particle is made of Au, Cu, Al, brass, bronze, TiN, Cr, stainless steel, alumina (Al ２ O ３ ), silica (SiO ２ The method according to claim 1, wherein the material is selected from the group consisting of bismuth oxychloride, glass materials, mica, and combinations thereof.

16. The conformal dielectric layer is TiO ２ ZnS, ZrO ２ , HfO ２ Fe ３ O ４ AlAs, Fe ２ O ３ , PbS, GaAs, InAs, SiO ２ MgF ２ , KBr, ZnO, Al ２ O ３ Selected from the group consisting of combinations thereof; The conformal barrier layer is Al ２ O ３ SiO ２ MgF ２ Selected from the group consisting of KBr, ZnO, and combinations thereof; The method according to claim 1, wherein the conformal absorber layer is selected from the group consisting of W, Cr, Ge, Ni, stainless steel, Pd, Ti, Si, V, TiN, Co, Mo, Nb, ferric oxide, and combinations thereof.

17. The conformal outer protective layer is SiO ２ Al ２ O ３ The method according to claim 4, selected from the group consisting of organosilanes, organophosphines, phosphates, and combinations thereof.

18. The second conformal barrier layer described above is Al ２ O ３ SiO ２ MgF ２ Selected from the group consisting of KBr, ZnO, and combinations thereof; The second conformal dielectric layer is TiO ２ , ZnS, ZrO ２ , HfO ２ , Fe ３ O ４ , AlAs, Fe ２ O ３ , PbS, GaAs, InAs, SiO ２ , MgF ２ , KBr, ZnO, Al ２ O ３ The method according to claim 5, selected from the group consisting of and combinations thereof.

19. The conformal outer protective layer is SiO ２ Al ２ O ３ The method according to claim 6, selected from the group consisting of organosilanes, organophosphines, phosphates, and combinations thereof.

20. The conformal dielectric layer has a thickness of 5 nm to 500 nm. The conformal barrier layer has a thickness of 50 nm or less. The method according to claim 1, wherein the conformal absorber layer has a thickness of 2 nm to 50 nm.

21. The second conformal barrier layer has a thickness of 50 nm or less. The method according to claim 5, wherein the second conformal dielectric layer has a thickness of 5 nm or more and 500 nm or less.

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