Pattern formation of complex metal oxide structure

Abstract

Various embodiments are disclosed relating to a method of manufacturing textured surface nanoimprint lithography using nanoparticle ink.SOLUTION: To provide a method that allows flexible pattern formation of a substrate having a feature with a complex geometry.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to the patterning of complex metal oxide structures.

Background Art

[0002] Structures of nanostructured metals, metal oxides, and metal nitrides are highly regarded for applications such as optics, metamaterials, and metasurfaces. In many applications, including optical applications and metamaterials / metasurfaces, complex geometries are required. Such structures include high aspect ratio structures (where height:width exceeds 4:1), structures having different tilt angles with respect to the normal of the substrate surface (such as blazed diffraction gratings), and patterns of feature elements where individual components have different heights and orientations and / or patterns of feature elements having significantly different areal densities (for example, some regions of the pattern include densely arranged feature elements, while other regions of the pattern contain no feature elements or contain a relatively sparse population of feature elements spaced far apart compared to the feature element size).

Summary of the Invention

Problems to be Solved by the Invention

[0003] Any of these requirements may be difficult to meet using conventional nanoimprint lithography.

Means for Solving the Problems

[0004] A method for manufacturing a textured surface is provided. The method includes disposing a template on a substrate and planarizing the template with nanoparticle ink. A method for manufacturing a textured surface is provided. The method includes planarizing an engraved template with nanoparticle ink to form a transfer printing master and contacting the transfer printing master with a substrate.

[0005] A method for manufacturing a textured surface is provided. The method includes disposing a template on a substrate, imprinting the template with a mold including a plurality of feature elements penetrating the template to form an imprinted template, planarizing the imprinted template with a nanoparticle ink, annealing the nanoparticle ink, and removing the imprinted template. In this method, the imprinting generates imprinted feature elements on the template that are substantially corresponding in shape and position to the feature elements on the mold, the nanoparticle ink substantially fills the imprinted feature elements of the template, and the nanoparticle ink includes indium tin oxide, titanium dioxide, aluminum oxide, silicon dioxide, metal oxides, metal nitrides, metal carbides, metal oxynitrides, metal oxycarbides, silicon oxide, metal borides, metal silicides, or combinations thereof.

[0006] A method for manufacturing a textured surface is provided. The method includes disposing a template on a first substrate, imprinting the template with a mold including a plurality of feature elements penetrating the template to form an imprinted template, planarizing the imprinted template with a nanoparticle ink to form a transfer printing master, annealing the nanoparticle ink, contacting the transfer printing master with a second substrate, and removing the transfer printing master to provide a plurality of feature elements disposed on the second substrate. In this method, the imprinting generates imprinted feature elements on the template that are substantially corresponding in shape and position to the feature elements on the mold, the nanoparticle ink substantially fills the imprinted feature elements of the template, and the nanoparticle ink includes indium tin oxide, titanium dioxide, aluminum oxide, silicon dioxide, metal oxides, metal nitrides, metal carbides, metal oxynitrides, metal oxycarbides, silicon oxide, metal borides, metal silicides, or combinations thereof.

[0007] In various embodiments, the method can easily fabricate complex structural geometries having a wide variety of feature element sizes and feature element distributions on a surface. In the various embodiments, the advantages of the present invention include a relatively low degree of shrinkage of the feature elements during other post-treatments or firing compared to the prior art and mechanical robustness. Advantageously, in various embodiments, this method enables the fabrication of high aspect ratio structures (height: width exceeding 4:1), structures with different tilt angles with respect to the normal of the substrate surface, and patterns of feature elements. The individual components differ in that they have significantly different heights, directions, and / or areal densities of the feature elements. Advantageously, in various embodiments, this method enables the fabrication of patterns containing densely packed high-density feature elements, where other regions of the pattern either do not contain feature elements or contain a relatively sparse population of feature elements that are spaced apart from the feature element size.

[0008] The drawings are not necessarily drawn to scale, but like numerals throughout the drawings represent substantially like components. The drawings generally illustrate, by way of example and not limitation, various embodiments of the present invention. The features shown in the drawings are not to scale and are for illustrative purposes and clarity only.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0010] Specific embodiments of the subject matter of this disclosure will be described with reference to the accompanying drawings, in which some examples of the subject matter of this disclosure are shown in part. The subject matter of this disclosure will be described in conjunction with the recited claims, but it should be noted that the exemplified subject matter is not intended to limit the claims of the subject matter of this disclosure.

[0011] Throughout this specification, values expressed in a range format should be construed in a flexible manner as including not only the numerical values explicitly recited as the bounds of the range, but also all individual numerical values within that range and sub - ranges within that range, as if each numerical value and sub - range were explicitly recited. For example, a range of “about 0.1% to about 5%” or “about 0.1% to 5%” includes not only from about 0.1% to about 5%, but also individual values (e.g., 1%, 2%, 3%, and 4%) and sub - ranges within the specified range (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%). The phrase “about X to Y” has the same meaning as “about X to about Y” unless otherwise indicated. Similarly, the phrase “about X, Y, or about Z” has the same meaning as “about X, about Y, or about Z” unless otherwise indicated.

[0012] As used herein, the terms “a,” “an,” and “the” are used to include one or more than one, unless the context clearly dictates otherwise. The term “or” is used to refer to a non - exclusive “or” unless otherwise indicated. “At least one of A and B” or “at least one of A or B” has the same meaning as “A, B, or A and B.” Further, it should be understood that expressions or terms used herein that are not otherwise defined are for illustrative purposes only and not for purposes of limitation. Section headings are used for the purpose of facilitating reading of the specification and are not to be construed as limitations. Information related to a section heading may be found not only within that particular section but also outside that section.

[0013] In the methods described in this specification, unless a temporal or operational order is explicitly stated, the individual acts may be performed in any order without departing from the technical idea of the present invention. Further, some specific acts may be performed simultaneously, unless the language of the claims explicitly states that they are to be performed separately. For example, the act of performing X in one claim and the act of performing Y in another claim may be performed simultaneously within a single operation, and the resulting process is included within the scope as described by the language of the process recited in the claims.

[0014] As used herein, the term "about" can tolerate some variation in a value or range, including the exactly stated value or range, for example, within 10%, 5%, or 1% of the stated value or the boundaries of the stated range.

[0015] As used herein, the term "substantially" refers to a majority or almost all, such as at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%. As used herein, the term "substantially free of" can mean having none or having a negligible amount, where the amount of the material does not affect the material properties of the composition containing the material, and the composition has from about 0 wt% to about 5 wt% of the material, or from about 0 wt% to about 1 wt%, or about 5 wt% or less, or from about 0 wt% to about 5 wt%, or about 4.5 wt%, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.01, or less than about 0.001 wt%, equal to, or more. The term "substantially free of" can mean having a negligible amount such that the composition has from about 0 wt% to about 5 wt% of the material, or from about 0 wt% to about 1 wt%, or about 5 wt% or less, or from about 0 wt% to about 5 wt%, or about 4.5 wt%, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.01, or less than about 0.001 wt%, equal to, or more, or about 0 wt%.

[0016] As used herein in conjunction with a molecule or organic group defined herein, the term "substituted" refers to a state in which one or more hydrogen atoms contained therein are replaced by one or more non-hydrogen atoms. As used herein, the term "functional group" or "substituent" refers to a group that can be on a molecule or organic group or a substituted group on a molecule or organic group. Examples of substituents or functional groups include halogens (e.g., F, Cl, Br, and I); oxygen atoms in groups such as hydroxy groups, alkoxy groups, aryloxy groups, aralkyloxy groups, oxo (carbonyl) groups, carboxyl groups including carboxylic acids, carboxylates, and carboxylic acid esters; sulfur atoms such as thiol groups, alkyl sulfides, aryl sulfides, sulfoxide groups, sulfone groups, sulfonyl groups, sulfonamide groups; nitrogen atoms in groups such as amines, hydroxyamines, nitriles, nitro groups, N-oxides, hydrazides, azides, enamines; and heteroatoms of various other groups, but are not limited thereto. Non-limiting examples of substituents that can be attached to a substituted carbon (or other) atom include F, Cl, Br, I, OR, OC(O)N(R)2, CN, NO, NO2, ONO2, azide, CF3, OCF3, R, O (oxo), S (thiono), C(O), S(O), methylenedioxyethylenedioxy, N(R)2, SR, SOR, SO2R, SO2N(R)2, SO3R, C(O)R, C(O)C(O)R, C(O)CH2C(O)R, C(S)R, C(O)OR, OC(O)R, C(O)N(R)2, OC(O)N(R)2, C(S)N(R)2, (CH2)O-2N(R)C(O)R, (CH2)O-2N(R)N(R)2, N(R)N(R)C(O)R, N(R)N(R)C(O)OR, N(R)N(R)CON(R)2, N(R)SO2R, N(R)SO2N(R)2, N(R)C(O)OR, N(R)C(O)R, N(R)C(S)R, N(R)C(O)N(R)2, N(R)C(S)N(R)2, N(COR)COR, N(OR)R, C(=NH)N(R)2, C(O)N(OR)R, and C(=NOR)R. Here, R can be hydrogen or a carbon-based moiety. For example, R is hydrogen, (C1-C 100)It may be hydrocarbyl, alkyl, acyl, cycloalkyl, aryl, aralkyl, heterocyclyl, heteroaryl, or heteroarylalkyl, or two R groups bonded to a nitrogen atom or adjacent nitrogen atoms may together with one or more nitrogen atoms form a heterocyclyl.

[0017] As used herein, the term "alkyl" refers to straight-chain and branched alkyl groups and cycloalkyl groups having from 1 to 40 carbon atoms, from 1 to about 20 carbon atoms, from 1 to 12 carbons, or in some embodiments from 1 to 8 carbon atoms. Examples of straight-chain alkyl groups include those having from 1 to 8 carbon atoms such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, and n-octyl groups. Examples of branched alkyl groups include, but are not limited to, isopropyl, isobutyl, sec-butyl, t-butyl, neopentyl, isopentyl, and 2,2-dimethylpropyl groups. As used herein, the term "alkyl" encompasses n-alkyl, isoalkyl, and anteisoalkyl groups, as well as other branched-chain forms of alkyl. Representative substituted alkyl groups may be substituted one or more times with any of the groups described herein, such as amino, hydroxy, cyano, carboxy, nitro, thio, alkoxy, and halogen groups.

[0018] As used herein, the term "radiation" refers to energy particles that move through a medium or space. Examples of radiation include visible light, infrared light, microwaves, radio waves, VLF waves, extremely low frequency waves, thermal radiation (heat), blackbody radiation, and the like.

[0019] As used herein, the term "light" refers to electromagnetic radiation within and near the wavelengths visible to the human eye and includes ultraviolet (UV) light and infrared light having wavelengths from about 10 nm to about 300,000 nm. The term "light" also includes microwave radiation having frequencies from about 300 MHz to about 300 GHz.

[0020] As used herein, the term "UV light" refers to ultraviolet light, which is electromagnetic radiation having a wavelength of from about 10 nm to about 400 nm. As used herein, the term "infrared light" refers to electromagnetic radiation having a wavelength between about 0.7 micrometers and about 300 micrometers.

[0021] As used herein, the term "solvent" refers to a liquid that can dissolve a solid, liquid, or gas. Non-limiting examples of solvents are silicone, organic compounds, water, alcohol, ionic liquids, and supercritical fluids.

[0022] As used herein, the term "coating" refers to a continuous or discontinuous layer of material on a coated surface. The material layer may penetrate the surface and can fill regions such as pores. The material layer may have any three-dimensional shape, including flat or curved surfaces. In one example, the coating can be formed on one or more surfaces, which can be porous or non-porous, by dipping into a bath of coating material.

[0023] As used herein, the term "surface" refers to the boundary or side of an object. The boundary or side can have any peripheral shape and may have any three-dimensional shape, including flat, curved, or angular. The boundary or side can be continuous or discontinuous.

[0024] Method for manufacturing a textured surface A method for manufacturing a textured surface is provided. The method includes placing a template on a substrate and flattening the template with nanoparticle ink. The substrate can be a non-conductive and non-reactive substrate such as glass, quartz, or a polymeric resin such as a PET sheet or a polyimide sheet. In some embodiments, the substrate is silicon dioxide glass coated with indium tin oxide (ITO).

[0025] In some embodiments, the template can be a crosslinked material. The template can be a polymer resin. For example, the template can be manufactured from a flexible and deformable polymer material. For example, polydimethylsiloxane (PDMS), crosslinked or non-crosslinked materials such as polymethyl methacrylate (PMMA), other monomer UV resins, polyurethanes, or perfluoropolyethers (PFPE). The planarization step may be performed by spin-coating or blade-coating the nanoparticle ink onto the template. The template may be deposited on the substrate by casting a mixture containing a PDMS precursor and a curing agent and then curing at a temperature above 50°C. When light is used for curing, the temperature may be selected from temperatures below 50°C. The thickness of the template may be from 0.01 mm to about 5 mm, or from about 0.5 mm to about 4.5 mm, or from about 1 mm to about 3 mm. In some embodiments, the template can have a thickness, which can be about 0.5 mm, about 1 mm, about 1.5 mm, about 2 mm, about 2.5 mm, about 3 mm, about 3.5 mm, about 4 mm, about 4.5 mm, about 5 mm, or any range or sub-range between these values.

[0026] The nanoparticle ink may exist as a dispersion of nanoparticles in a solvent. The nanoparticle ink can include nanoparticles including indium tin oxide, titanium dioxide, aluminum oxide, silicon dioxide, metal oxides, metal nitrides, metal carbides, metal oxynitrides, metal oxycarbides, metal borides, metal silicides, graphene, graphene oxide, or combinations thereof.

[0027] In some embodiments, the nanoparticles have a number average and volume average particle size of from about 1 nm to about 20 nm. In some embodiments, the nanoparticles have a number average particle size of from about 1 nm to about 19 nm, from about 2 nm to about 18 nm, from about 3 nm to about 17 nm, from about 4 nm to about 16 nm, from about 5 nm to about 15 nm, from about 6 nm to about 14 nm, from about 7 to about 13 nm, or any sub-range therebetween. In some embodiments, the nanoparticles can have a volume average particle size, which can be about 1 nm, about 2 nm, about 3 nm, about 4 nm, about 5 nm, about 6 nm, about 7 nm, about 8 nm, about 9 nm, about 10 nm, about 11 nm, about 12 nm, about 13 nm, about 14 nm, about 15 nm, about 16 nm, about 17 nm, about 18 nm, about 19 nm, about 20 nm, or any range or sub-range between these values.

[0028] In some embodiments, the nanoparticles are crystalline. In some embodiments, the dispersion has an alcohol solvent as the liquid phase. In some embodiments, the alcohol is methanol, isopropanol, 1,2-propanediol, or a mixture thereof. In some embodiments, the alcohol can be ethanol, butanol, ethylene glycol, (1,2- or 1,3- or 1,4-) butanediol, and mixtures thereof. In some embodiments, the nanoparticle ink can include a binder component. In some embodiments, the binder component can include siloxane. The binder may be present as a sol-gel precursor in the dispersion.

[0029] FIG. 1 shows a mold (100) having a plurality of feature elements (110), a substrate (120), and a template (130). After imprinting the template with the mold, the feature elements (140) imprinted on the template substantially correspond in shape and position to the feature elements of the mold. The imprinted template can be planarized with nanoparticle ink (150) to substantially fill the imprinted feature elements with nanoparticle ink (160). After removing the template, the substrate includes feature elements (170) composed of nanoparticle material from the nanoparticle ink.

[0030] In some embodiments, the top surface (the surface to be imprinted) of the template (130) before imprinting may be coated with a material that can create a hydrophobic / hydrophilic contrast between the top surface of the template and the imprinted feature elements / vacancies. Such a coating can fill the feature elements without leaving a residue layer on the surface of the template.

[0031] This method can further include imprinting the template with a mold that includes a plurality of feature elements passing through the template to form the imprinted template. The mold can be made of, for example, a rigid mold made of PDMS (polydimethylsiloxane), PUA (polyurethane acrylate), PMMA (polymethyl methacrylate), silicon, nickel, quartz, or ZrO2. The imprinting can be accomplished manually or using a suitable apparatus such as the Nanonex NX - 2000 or NX - 2608BA. In some embodiments, the mold has at least one substantially flat surface and at least one of the feature elements has a side surface that forms an acute angle with the mold. This acute angle can be in the range of about 10 degrees to about 89 degrees, in the range of about 20 degrees to about 60 degrees, or in a range equal to or less than, equal to, or greater than about 10 degrees, 15 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees, 80 degrees, 85 degrees, or about 89 degrees. FIG. 2 shows a mold having a feature element (210) with an acute angle (220) with respect to the flat surface on the mold (200).

[0032] The feature element can have a height:width aspect ratio, which can be from about 2:1 to about 10:1, from about 3:1 to 10:1, from about 4:1 to about 10:1, from about 5:1 to about 10:1, from about 6:1 to about 10:1, from about 7:1 to about 10:1, from about 9:1 to about 10:1, or any range or sub-range between these values. In some embodiments, the height:width aspect ratio of the feature element can be about 2:1, about 3:1, about 4:1, about 5:1, about 6:1, about 7:1, about 8:1, about 9:1, about 10:1, or any range or sub-range between these values.

[0033] The feature element can have a width:height aspect ratio, which can be from about 2:1 to about 10:1, from about 3:1 to 10:1, from about 4:1 to about 10:1, from about 5:1 to about 10:1, from about 6:1 to about 10:1, from about 7:1 to about 10:1, from about 9:1 to about 10:1, or any range or sub-range between these values. In some embodiments, the width:height aspect ratio of the feature element can be about 2:1, about 3:1, about 4:1, about 5:1, about 6:1, about 7:1, about 8:1, about 9:1, about 10:1, or any range or sub-range between these values.

[0034] In some embodiments, the height of the feature element can be from about 0.05 microns to about 30 microns, from about 0.5 microns to about 25 microns, from about 1 micron to about 22 microns, from about 2 microns to about 20 microns, from about 3 microns to about 18 microns, from about 4 microns to about 16 microns, from about 5 microns to about 14 microns, from about 6 microns to about 12 microns, or any range or sub-range between these values.

[0035] The height of the characteristic element can be about 0.05 microns, 1 micron, about 2 microns, about 3 microns, about 4 microns, about 5 microns, about 6 microns, about 7 microns, about 8 microns, about 9 microns, about 10 microns, about 11 microns, about 12 microns, about 13 microns, about 14 microns, about 15 microns, about 16 microns, about 17 microns, about 18 microns, about 19 microns, about 20 microns, about 21 microns, about 22 microns, about 23 microns, about 24 microns, about 25 microns, or a range or sub-range between these values.

[0036] In some embodiments, the width of the characteristic element can be from about 0.05 microns to about 30 microns, from about 0.5 microns to about 25 microns, from about 1 micron to about 22 microns, from about 2 microns to about 20 microns, from about 3 microns to about 18 microns, from about 4 microns to about 16 microns, from about 5 microns to about 14 microns, from about 6 microns to about 12 microns, or any range or sub-range between these values. The width of the characteristic element can be from about 0.05 microns to about 1 micron, about 2 microns, about 3 microns, about 4 microns, about 5 microns, about 6 microns, about 7 microns, about 8 microns, about 9 microns, about 10 microns, about 11 microns, about 12 microns, about 13 microns, about 14 microns, about 15 microns, about 16 microns, about 17 microns, about 18 microns, about 19 microns, about 20 microns, about 21 microns, about 22 microns, about 23 microns, about 24 microns, about 25 microns, or a range or sub-range between these values.

[0037] In some embodiments, the depth of the feature elements can be from about 0.05 microns to about 30 microns, from 0.5 microns to about 25 microns, from about 1 micron to about 22 microns, from about 2 microns to about 20 microns, from about 3 microns to about 18 microns, from about 4 microns to about 16 microns, from about 5 microns to about 14 microns, from about 6 microns to about 12 microns, or any range or sub-range between these values. The depth of the feature elements can be about 0.05 microns, 1 micron, about 2 microns, about 3 microns, about 4 microns, about 5 microns, about 6 microns, about 7 microns, about 8 microns, about 9 microns, about 10 microns, about 11 microns, about 12 microns, about 13 microns, about 14 microns, about 15 microns, about 16 microns, about 17 microns, about 18 microns, about 19 microns, about 20 microns, about 21 microns, about 22 microns, about 23 microns, about 24 microns, about 25 microns, or a range or sub-range between these values.

[0038] In some embodiments, the feature elements are arranged in a periodic pattern. In some embodiments, the feature elements are arranged randomly. In some embodiments, the feature elements are arranged in an aperiodic pattern. In some embodiments, the feature elements of the mold may be arranged such that one part of the mold is a high surface density part where the feature elements are arranged close to each other, and another part of the mold is a pattern that does not contain feature elements or contains relatively few feature elements arranged far apart compared to the feature element size. FIG. 3 shows a part (320) of a mold (300) where the feature elements are dense and a part (310) of a mold having a relatively small number of feature elements arranged far apart relative to the size of the feature elements.

[0039] In some embodiments, the separation between any two feature elements can be from about 0.05 microns to about 1000 microns, from about 5 microns to about 900 microns, from about 10 microns to about 800 microns, from about 20 microns to about 700 microns, from about 50 microns to about 600 microns, from about 75 microns to about 500 microns, from about 100 microns to about 400 microns, or any range or sub-range between these values.

[0040] The separation between any two feature elements can be about 0.05 microns, about 1 micron, about 5 microns, about 10 microns, about 15 microns, about 25 microns, about 35 microns, about 45 microns, about 55 microns, about 65 microns, about 75 microns, about 85 microns, about 95 microns, about 105 microns, about 115 microns, about 125 microns, about 135 microns, about 145 microns, about 155 microns, about 165 microns, about 175 microns, about 185 microns, about 195 microns, about 205 microns, about 215 microns, about 225 microns, about 235 microns, about 245 microns, about 255 microns, about 265 microns, about 275 microns, about 285 microns, about 295 microns, about 305 microns, about 315 microns, about 325 microns, about 335 microns, about 345 microns, about 355 microns, about 365 microns, about 375 microns, about 385 microns, about 395 microns, about 405 microns, about 415 microns, about 425 microns, about 435 microns, about 445 microns, about 455 microns, about 465 microns, about 475 microns, about 485 microns, about 495 microns, or any range or sub-range between these values.

[0041] In some embodiments, the imprinting includes imprint lithography without residue. Based on the adjustment of the surface energy or surface tension of the template, substrate, and ink, and the adjustment of the ink concentration and coating speed, an imprint without residue can be performed. In some embodiments, said imprinting generates on said template an imprinted feature element whose shape and position substantially correspond to said feature element on said mold. Thus, by imprinting, a negative feature element corresponding to the size and position of the feature element of the mold can be generated on the template. By spin-coating the nanoparticle ink so as to substantially fill the imprinted feature element within the template, the template including the imprinted feature element can complete planarization.

[0042] This method can further include first annealing the imprinted template. The first annealing may include heating, microwave irradiation, visible light irradiation, infrared light irradiation, and ultraviolet light irradiation. In embodiments where electromagnetic radiation is used for annealing, the light source may be a constant illumination light source, or the electromagnetic radiation may be deployed through a pulsed light source that delivers intense pulsed light. In some embodiments, the annealing can be at 100°C, 200°C, 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, or 1000°C, or any range or sub-range therebetween. In some embodiments, the annealing is performed at a temperature from 100°C to 500°C for a period from 5 minutes to 2 hours. In some embodiments, the annealing is performed at a temperature between 100°C and 1000°C for a period that is 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, or 120 minutes, or any range or sub-range between these values.

[0043] In some embodiments, the method includes removing the template or the imprinted template from the substrate. Removing the template or the imprinted template can include dissolution, calcination, or irradiation by microwave irradiation, visible light, infrared light, or ultraviolet light. When the template or the imprinted template is removed, a feature element made of cured or annealed nanoparticle ink corresponding to the size and position of the feature element on the mold appears.

[0044] Annealing the substrate and the nanoparticle ink feature elements can be performed under the conditions described herein. In some embodiments, the first annealing dries / fuses the particles within the template. In some embodiments, the second annealing promotes bonding and adhesion of the nanoparticles to the substrate and between the nanoparticles.

[0045] In some embodiments, a method of manufacturing a textured surface is provided. The method includes placing a template on a substrate, imprinting the template with a mold that includes a plurality of feature elements passing through the template to form an imprinted template, planarizing the imprinted template with a nanoparticle ink, annealing the nanoparticle ink, and removing the imprinted template. In this method, the imprinting generates imprinted feature elements on the template that are substantially corresponding in shape and position to the feature elements on the mold, the nanoparticle ink substantially fills the imprinted feature elements of the template, and the nanoparticle ink includes indium tin oxide, titanium dioxide, aluminum oxide, silicon dioxide, metal oxides, metal nitrides, metal carbides, metal oxynitrides, metal oxycarbides, silicon oxide, metal borides, metal silicides, or combinations thereof.

[0046] Method of manufacturing a textured surface using a transfer printing master The method of manufacturing a textured surface using a transfer printing master shares many similarities with the methods described herein. Any of the materials, methods, and techniques used above can also be used in the following manufacturing methods.

[0047] In some embodiments, a method of manufacturing a textured surface is provided. The method includes flattening an engraved template with nanoparticle ink to form a transfer printing master and contacting the transfer printing master with a substrate. The composition of the nanoparticle ink and the substrate may be as described above. The transfer printing master may have any composition suitable for the templates or engraved templates described herein.

[0048] In some embodiments, the contacting includes a sheet-fed or roll-to-roll transfer process. The method may further include disposing a template on a first substrate and engraving the template with a mold having a plurality of feature elements passing through the template to form an engraved template. In some embodiments, the method further includes removing the transfer printing master to provide a plurality of feature elements disposed on a second substrate. Removing the transfer printing master can be accomplished, for example, by dissolution, calcination, or irradiation with microwave, visible light, infrared, or ultraviolet light. Optionally, the light may be pulsed.

[0049] In some embodiments, the surface of the template includes a hard coat. The hard coat can include silica, perfluoropolyether, fluorine-containing acrylate, epoxide, fluorine-modified silica material, or a mixture thereof.

[0050] In some embodiments, the engraved template includes a crosslinked material. In some embodiments, the template includes a polymer resin. The template can include any of the materials described herein. Thus, engraving can generate negative-type feature elements corresponding to the size and position of the feature elements of the mold in the template. Flattening of the template including the engraved feature elements can be accomplished by spin-coating nanoparticle ink to substantially fill the engraved feature elements in the template.

[0051] In some embodiments, the imprinting includes imprint lithography without residue. With or without imprint lithography without residue, the imprinting can generate imprinted feature elements on the imprinted template that substantially correspond in shape and position to the feature elements on the mold. In some embodiments, the nanoparticle ink substantially fills the imprinted feature elements of the imprinted template. The nanoparticle ink can include indium tin oxide, titanium dioxide, aluminum oxide, silicon dioxide, metal oxides, metal nitrides, metal carbides, metal oxynitrides, metal oxycarbides, metal borides, metal silicides, or combinations thereof.

[0052] The size, shape, and spacing of the feature elements can be as already described herein. In some embodiments, the method further includes annealing the substrate. The annealing can be performed using any of the methods and conditions already described herein. In some embodiments, the annealing includes heating, microwave irradiation, visible light irradiation, infrared irradiation, and ultraviolet irradiation.

[0053] FIG. 4 shows a mold (400) having a plurality of feature elements (410), a substrate (420), and a template (430). After imprinting the template with the mold, the feature elements (440) imprinted on the template substantially correspond in shape and position to the feature elements on the mold. The imprinted template can be planarized with nanoparticle ink (450) to substantially fill the imprinted feature elements with nanoparticle ink (460) to form a transfer printing master (465). This transfer printing master is brought into contact with a second substrate (470), and after removing the transfer printing master, feature elements (480) composed of nanoparticle material from the nanoparticle ink are disposed on the second substrate.

[0054] In some embodiments, the transfer printing master (465) and the nanoparticle ink (460) are annealed before contacting the second substrate (470). The template can include a material that is transparent to the irradiation used to heat, anneal, or both heat and anneal the structure without substantially heating the transfer printing master.

[0055] Products including a textured surface can be formed by any of the methods described herein. Examples of articles that can be manufactured using the methods described herein include, but are not limited to, lenses, flat lenses, metalenses, displays, flexible displays, touch panels, sensor surfaces, shield foils, and blazed diffraction gratings. The article can optionally be optically transparent. For example, the article can be optically transparent to electromagnetic radiation having wavelengths in the visible and near-infrared spectra (e.g., in the range of about 400 nm to about 1400 nm). The article can be a device such as a virtual reality device or an augmented reality device, or a component of such a device. For example, the article can be a component of a lens, glasses, or goggles for virtual reality or augmented reality.

[0056] In some embodiments, a method of manufacturing a textured surface is provided. The method includes disposing a template on a first substrate, imprinting the template with a mold including a plurality of feature elements passing through the template to form an imprinted template, planarizing the imprinted template with nanoparticle ink to form a transfer printing master, annealing the nanoparticle ink, contacting the transfer printing master with a second substrate, and removing the transfer printing master to provide a plurality of feature elements disposed on the second substrate. In this method, the imprinting generates imprinted feature elements on the template that are substantially corresponding in shape and position to the feature elements on the mold, the nanoparticle ink substantially fills the imprinted feature elements of the template, and the nanoparticle ink includes indium tin oxide, titanium dioxide, aluminum oxide, silicon dioxide, metal oxides, metal nitrides, metal carbides, metal oxynitrides, metal oxycarbides, silicon oxide, metal borides, metal silicides, or combinations thereof.

[0057] Structures including residual nanoporosity may result from the feature elements deposited using the methods described herein. Such porosity may be present in films coated on the surface from nanoparticle-based inks, in feature elements printed directly on the substrate, and in feature elements prepared for subsequent transfer to the substrate or for recovery of isolated structures.

[0058] Furthermore, such porosity may result when using inks that contain only nanoparticle dispersions or inks that contain both nanoparticles and a sol-gel type precursor or a binder or other binder material incorporated into the desired product's feature elements. In some cases, such residual porosity may be desirable, for example, for ion transport through sensors or battery electrodes. In other cases, the residual porosity is detrimental in terms of structural properties, performance, mechanical stability, shrinkage, or both during calcination.

[0059] Reducing the residual porosity (densification) can adjust material properties such as refractive index and conductivity, and improve mechanical stability. Such densification occurs by reaction and / or deposition within the residual pores of the feature elements described herein, improving the properties. In some embodiments, the deposition includes the use of chemical vapor deposition (CVD) to deposit a controlled amount, composition, thickness, or any combination of these properties of a material within the pores of the feature elements described herein.

[0060] In some embodiments, the deposition includes the use of atomic layer deposition (ALD) to deposit a controlled amount, composition, thickness, or any combination of these properties of a material within the pores of the feature elements described herein. In some embodiments, the deposition by CVD or ALD can deposit a material of substantially the same composition as the porous feature element or a material of a different composition than the porous feature element. The ALD process improves the mechanical stability of the pattern printed on the mold and the structure generated on the mold before transfer or before removing the mold, and facilitates the transfer of the pattern.

[0061] In some embodiments, ALD, CVD, or both can be used to apply an adhesion layer (of the same or different composition as the composition of the feature element to be patterned) to the structure to be transferred. In some embodiments, ALD, CVD, or both can also be used to enhance the adhesion of the feature elements described herein to the substrate. In some embodiments, ALD, CVD, or both can be used to reduce the surface roughness of the feature elements described herein.

[0062] The ALD process described herein can be applied to structures created by conventional nanoimprint lithography (NIL) printing using metal oxide inks. Structures created by the NIL printing process published by Kothari et al. (Kothari, R; Beaulieu, MR; Hendricks, NR; Li, SK; Watkins, JJ, Chemistry of Materials, Vol. 29, No. 9, pp. 3908 - 3918) can be processed by the ALD process described herein.

[0063] In ALD, the surface or substrate is continuously exposed to a first reactant and a second reactant. The first and second reactants are deposited in a non - overlapping manner. In ALD, the deposition of a reactive substance such as the first reactant onto the surface is limited by the amount of reactive sites on the surface. Once all the reactive sites are consumed, no further reaction (e.g., film formation of layer thickness or pore filling) occurs until additional reactive substance is added. Residual first reactant molecules may be flushed away before the addition and deposition of the second reactant. Thus, after the deposition of the first reactant, the second reactant is deposited. A single ALD cycle includes depositing the first reactant, optionally flushing away excess first reactant, depositing the second reactant deposition, and optionally flushing away excess second reactant. By repeating this process continuously, the thickness of the deposited layer or the amount of reduction in porosity can be finely adjusted.

[0064] Deposition may be carried out to reduce porosity in a variety of ways, ranging from a thin surface coating of pores to substantial filling of pores. Such deposition can be carried out in a coating from nanoparticle - based inks, in free - standing printed features without support, or within a nanoparticle composition contained within features of a master mold. Such deposition can be carried out before or after the firing (curing or annealing) of the coated or printed film and features.

[0065] In some embodiments, a spatial ALD process can be used. In spatial ALD, the reagents (the first reactant and the second reactant) are spatially separated by an inert gas, and the substrate is moved relative to the ALD head or the ALD head is moved relative to the substrate. Spatial ALD may be used in a roll-to-roll process for feature elements.

[0066] In some embodiments, a method of manufacturing a textured surface includes performing at least one cycle of atomic layer deposition (ALD) on a patterned feature element, the ALD including depositing a first reactant and a second reactant, the first reactant including y MX y MR y M(NR) y M(OR) y MX z R y MX z (NR) y MX z (OR) 1-20 MCp2 or combinations thereof, the second reactant including water, y and z each independently being an integer from 2 to 8, each X independently being F, Cl, Br, or I, each R independently being hydrogen or a substituted or unsubstituted C

[0067] Suitable metals can include Al, Ti, Si, Cu, Pd, Ni, Ru, Ta, Zr, Zn, In, Hf, Sn, Pt, and combinations thereof. In some embodiments, the metal is Ti. In some embodiments, the first reactant is tetrakis(dimethylamino)titanium (TDMAT) having the following structure.

[0068]

Chemical formula

[0069] The thickness of the deposited material after each ALD cycle can be about 0.01 Å to 1.0 Å, 0.05 Å to 1.0 Å, 0.1 Å to 0.9 Å, 0.1 Å to 0.8 Å, 0.1 Å to 0.7 Å, 0.2 Å to 0.7 Å, 0.2 Å to 0.6 Å, or any range or sub-range between these values. In some embodiments, the thickness of the deposited material after each ALD cycle can be 0.01 Å, 0.05 Å, 0.2 Å, 0.3 Å, 0.4 Å, 0.5 Å, 0.6 Å, 0.7 Å, 0.8 Å, 0.9 Å, 1.0 Å, or a range between these values. The number of ALD cycles used can be about 1 to 5000 cycles, 1 to 4000 cycles, 1 to 3000 cycles, 1 to 2000 cycles, 1 to 1000 cycles, 1 to 500 cycles, 1 to 400 cycles, 1 to 300 cycles, 1 to 200 cycles, 1 to 100 cycles, 1 to 90 cycles, 1 to 80 cycles, 1 to 70 cycles, 1 to 60 cycles, 1 to 50 cycles, 1 to 40 cycles, 1 to 30 cycles, 1 to 20 cycles, or any range between these values. In some embodiments, the number of ALD cycles can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380, 400, 420, 440, 460, 480, 500, or any range or sub-range between these values.

[0070] After the deposition of the desired material on the textured surface by ALD is complete, the textured surface can be heated at a temperature of about 200°C to 1000°C, 200°C to 900°C, 200°C to 800°C, 200°C to 700°C, 200°C to 600°C, 200°C to 500°C, 400°C to 800°C, or any range between these values. In some embodiments, after depositing the desired material with ALD on the textured surface, the textured surface can be heated to about 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, or any sub-range between these values. The heating can be carried out for about 1 to 12 hours, 1 to 11 hours, 1 to 10 hours, 1 to 9 hours, 1 to 8 hours, 1 to 7 hours, 1 to 6 hours, 1 to 5 hours, 1 to 4 hours, 1 to 3 hours, 1 to 2 hours, 2 to 6 hours, 3 to 5 hours, or in a range between these values. In some embodiments, the heating can be performed for about 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, or any range or sub-range between these values.

[0071] In some embodiments, after the ALD process, the feature element may exhibit a shrinkage of about 1% to 15%, 1% to 4%, 1% to 13%, 1% to 12%, 1% to 11%, 1% to 10%, 1% - 9%, 1% - 8%, 1% - 7%, 1% - 6%, 1% - 5%, 1% - 4%, or 1% - 3%. In some embodiments, after the ALD process, the feature element may exhibit a shrinkage of 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%. It can be 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, or any range or sub-range between these values. In some embodiments, following the ALD process, the structure may be annealed by exposure to electromagnetic radiation. The electromagnetic radiation can be delivered by microwave irradiation, visible light irradiation, infrared irradiation, and ultraviolet irradiation. In embodiments using electromagnetic radiation for annealing, the light source may be a constant illumination source, or the electromagnetic radiation may be delivered through a pulsed light source that delivers intense pulsed light.

[0072] In some embodiments, after the ALD process, the feature element may exhibit a refractive index of about 1.2 - 4.0, 1.2 - 3.8, 1.2 - 3.6, 1.2 - 3.4, 1.2 - 3.2, 1.2 - 3.0, 1.2 - 2.8, 1.2 - 2.6, 1.2 to 2.4, 1.2 to 2.2, 1.2 to 2.0, 1.2 to 1.8, 1.2 to 1.6, 1.2 to 1.4, or a range or sub-range between these values. In some embodiments, after the ALD process, the feature element may exhibit a refractive index of about 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, or any range or sub-range between these values. In some embodiments, an ALD can be used to generate a gradient of refractive index values. This gradient can result from forming a shell of ALD deposited material over or around the formed feature element.

[0073] In some embodiments, the ALD process described herein can fill the pores of the feature elements described herein and minimize shrinkage of the printed or transferred feature elements during post - processing, annealing, or both. In some embodiments, ALD fills the pores of the feature elements with TiO2. In some embodiments, after the feature elements are heated at a temperature of about 200 °C to 1000 °C or after the feature elements are exposed to light, the feature elements have a shrinkage of about 1% to 15%. In some embodiments, after the feature elements are heated at a temperature of about 200 °C to 1000 °C or after the feature elements are exposed to light, the feature elements have a refractive index of about 1.2 to 4.0.

[0074] In the pore filling by ALD, the refractive index of the article can be adjusted or tuned. In some embodiments, the adjustment or tuning using ALD is used to correct manufacturing errors, for example, to make the refractive index a desired value not present in the formed article.

[0075] However, the ALD process can also be used to adjust the refractive index value of an article intentionally formed to have a refractive index value below a given desired refractive index. Just imprinting may not be able to accurately achieve a given refractive index value. However, by using imprinting, a precise given refractive index value within about 10%, or about 9%, 8%, 7%, or about 6% of the given refractive index value can be obtained. Then, ALD can be used to finely adjust the refractive index value within about 5%, 4%, 3%, 2%, 1%, 0.5%, 0.05%, or about 0.01% of the given value or to the given value.

[0076] ALD can finely adjust the refractive index of a product by reducing the porosity of the product. In some embodiments, the porosity may result from unintentionally generated porosity formed during the imprinting process. In other embodiments, the porosity of an article can be intentionally induced. For example, nanoparticles can be functionalized with organic ligands that induce porosity in the article. The porosity can be further adjusted by controlling the particle size distribution of the nanoparticles in the ink, the spin coating time, or by the selection and use of a binder. ALD can be used to fill intentionally generated pores to adjust the refractive index.

Example

[0077] Various embodiments of the present invention can be better understood by referring to the following examples shown by way of illustration. The present invention is not limited to the examples shown herein. Example 1 Deposition of TiO2 on a Nanoparticle Ink Film A film prepared by spin coating from a nanoparticle (NP)-based ink exhibits a refractive index (RI) of 1.82. This nanoparticle-based ink contained 1,2-propanediol, methanol, isopropanol, and titanium diisopropoxide bis(acetylacetonate). After heating to 250 °C, the film exhibits a refractive index of approximately 1.86. After 25 deposition cycles, the film exhibits a refractive index of 2.25. The lateral shrinkage after heating at 475 °C for 4 hours was compared for a TiO2 film coated from a TiO2 nanoparticle ink and a TiO2 coating prepared using the nanoparticle-based ink and then depositing TiO2 in the pores by ALD. The shrinkage of the film without ALD treatment was 18.8%, while the shrinkage of the films treated with 25 and 150 ALD cycles was 6.8% and 3.7%, respectively. The porosity can be calculated from the refractive index. For the film without ALD treatment, the porosity was 31.1% and 28.1% before and after heating at 475 °C for 4 hours, respectively, while for the film subjected to 25 ALD cycles, the porosity was 9.0% and 6.9% before and after heating at 475 °C for 4 hours, respectively.

[0078] Depositing a sediment of a material with a low intrinsic refractive index (such as SiO2) in the pores to reduce the porosity can reduce the increase in the refractive index compared to the case of using TiO2. The use of materials such as SiO2 provides another way to adjust the refractive index value.

[0079]

Table 1

[0080]

Table 2

[0081]

Table 3

[0082]

Table 4

[0083]

Table 5

[0084] Method: A nanoparticle dispersion was prepared by diluting the stored TiO2 nanoparticles from 20 wt% to 2.5 - 10 wt% with methanol. Then, this dispersion was sonicated for 5 minutes. After sonication, 10% titanium diisopropoxide bis(acetylacetonate) or tetraethyl orthosilicate (TEOS) was added to this dispersion (10% solids based on the mass of TiO2 nanoparticles), and it was sonicated again for 5 minutes.

[0085] Before preparing the planar or patterned film, the silicon substrate was exposed to oxygen plasma for 5 minutes to activate the surface. The planar film was spin-coated at 3000 rpm until all solvents were removed. A patterned structure was prepared. Briefly, a stamp was prepared by pouring a PDMS prepolymer onto a fluorinated silicon wafer containing various nanopatterns. After curing, the PDMS stamp could be easily removed and used or reused for NIL with a solvent. The diluted TiO2 dispersion was spin-coated at 3000 rpm for 5 - 30 seconds at 5% RH, and then the PDMS stamp was carefully placed on top of the film. After placing it on a hot plate at 50 °C for several minutes and removing the PDMS stamp, the imprinted TiO2 appeared.

[0086] For high aspect ratio (HAR) pillars, an improved technique was adopted. A fluorinated silicon master containing HAR vias was spin-coated with Fluorolink MD700 prepolymer containing 2% DMPA (relative to the prepolymer weight), and then placed upside down on a PET piece with a cured NOA60 coating. The entire assembly was placed in a Nanonex imprint tool (NX-2600BA), evacuated for 2 minutes, and then imprinted and UV-cured at 10 psi for 15 minutes. After separation, the fluoropolymer replica mold containing the pillars was adhered to a Si wafer with a layer of NOA60 using Nanoex to ensure a flat and smooth surface. For these HAR patterns, a composite PDMS stamp was prepared to improve the transfer of HAR feature elements. Briefly, the production of this composite stamp involves mixing VS, TCS, Pt-DVS, and MCP in appropriate amounts, spin-coating a layer on the replica master, curing on a hot plate, and back-supporting with Sylgard184. After curing, a TiO2 nanoparticle-based ink was imprinted using an HPDMS stamp. The imprinted HAR columnar feature elements were irradiated with NIR (Adphos126-125NIR dryer) through the stamp before separation.

[0087] Various numbers of deposition cycles were performed on the films and structures using a Cambridge NanoTech Savannah90 ALD system. Unless otherwise indicated, all depositions were carried out at 250 °C. The subsequent TiO2 deposition recipe consisted of a 0.1 s pulse of TDMAT followed by a 0.015 s pulse of H2O, with an expected film growth rate of approximately 0.4 Å / cycle. The deposition of Al2O3 was similarly carried out with a 0.015 s pulse of H2O followed by a 0.015 s pulse of TMA corresponding to a film growth rate of approximately 1 Å / cycle.

[0088] Characteristic evaluation: The refractive index and film thickness of the planar film were measured by variable-angle spectroscopic ellipsometry using an RC2 spectroscopic ellipsometer from JA Woollam, together with the transmission and reflection intensities. The spectroscopic ellipsometry data were modeled using a Cauchy model for the transparent region of TiO2. A Kramers-Kronig consistent b-spline model was used to include the absorption region (UV).

[0089] Top-down and cross-sectional films and nanostructures were analyzed by a scanning electron microscope using a FEI Magellan400FESEM. The surface roughness was measured using an atomic force microscope (Veeco Dimension3100). The composition as a function of film depth was characterized by X-ray photoelectron spectroscopy (XPS) using a Quantum2000 Scanning ESCA microprobe (Physical Electronics)

[0090] ALD on planar films Both nanoparticle-based films and nanostructures were densified using ALD. The nanoparticle dispersion was spin-coated onto Si substrates, and nanostructures and thin films were prepared by either imprinting or complete drying before ALD. For reference, samples were deposited on nanoparticle-based films and on bare silicon for each ALD treatment.

[0091] Table 6 shows the predicted thicknesses of various deposits on bare Si calculated according to a film growth rate of 0.4 Å / cycle provided by CambridgeNanoTech. The measured values of both refractive index and thickness are in good agreement with the predicted results. A decrease in refractive index is expected with the number of cycles, which is due to discontinuous film formation by just a few deposition cycles. The nanoparticle films were characterized before and after each ALD treatment.

[0092] [Table 6] The thickness and refractive index of the planar TiO2 nanoparticle film were measured after spin coating and after heat treatment at 250 °C as a control since the deposition was carried out at 250 °C. The refractive index of the film increased from 1.82 to 1.86 after spin coating, and the film thickness decreased from 48 nm to 44 nm after heat treatment at 250 °C for 2 hours. These slight changes may be due to the gentle densification of the nanoparticle film. To determine the effect of ALD on the TiO2 nanoparticle film, several thin films were prepared from the nanoparticle dispersion and subjected to various numbers of ALD cycles.

[0093] The total film thickness measured after 380 ALD cycles was 72 nm and the refractive index was 2.26, but after only 25 cycles, the change in film thickness was negligible and the refractive index increase was about 24%. The total refractive index as a function of wavelength for 50 ALD cycles emphasizes the dramatic and nearly bulk values that can be achieved in short ALD process steps. This result means that the intrinsic porosity of the nanoparticle film is being reduced by ALD, which can also be observed from the changes in the film surface morphology with increasing ALD cycles. Table 7 shows the porosities of the nanoparticle film after 0, 25, 50, 150, and 380 ALD cycles after spin coating, before and after heat treatment at 475 °C for 4 hours, calculated using the Lorentz-Lorenz equation.

[0094]

Table 7

[0095] ALD on a patterned surface Unlike a planar film for which the refractive index can be reliably measured, different techniques are required to confirm the deposition by ALD into the pores of a patterned surface. To confirm the deposition into the pores using ALD, aluminum oxide (Al2O3) was deposited on a TiO2 diffraction grating and the presence of oxygen, aluminum, and titanium across the entire diffraction grating was observed using EDS. In this example, 100 cycles of Al2O3 corresponding to approximately 10 nm were deposited on the imprinted lines so that an elemental contrast between the imprinted particles and the ALD deposited material could be obtained.

[0096] Following deposition, changes in the size and surface texture of the characteristic elements were observed to confirm the deposition of Al2O3 by ALD. The presence of oxygen throughout the diffraction grating was indicated by EDS. This was as expected since oxygen is a component of both TiO2 and Al2O3. The presence of aluminum showed a gradient, with aluminum concentrated at the edges of the diffraction grating and decreasing in concentration towards the interior of the diffraction grating. Titanium, on the contrary, showed a result where titanium was concentrated towards the interior of the diffraction grating. These obtained results are in agreement with the expected results. Al2O3 first deposits inside the pores of the nanoparticles and then continues to deposit conformally on the outside of the diffraction grating. This confirmation densified the patterned TiO2 nanoparticle-based structure with ALD TiO2.

[0097] For some photonic and metasurface applications, patterned structures with an aspect ratio (AR) greater than 1 were generated. The pillars were fabricated by direct patterning, without the need for an etching process or a resist removal process, and could be scaled up for wafer-based manufacturing. In contrast, for thin, linear diffraction gratings, the HAR pillars require a stamp-mediated annealing process before removing the stamp to promote sufficient bonding between the nanoparticles without breaking the pillars during stamp removal. After placing the PDMS stamp on the nanoparticle film, the solvent was dried on a hot plate and NIR irradiation was performed on the assembly of the substrate and the stamp for 20 seconds.

[0098] Columns can be effectively patterned over a wide area. To compare the change in characteristic feature dimensions between master imprinting and nanoparticle imprinting, UV curable polymer NOA60 was imprinted. For the HAR column part on the silicon master, the diameter of the imprinted NOA60 column was measured to be 140 ± 5 nm at the top of the column and the height was 1.1 μm, so the HAR is 7.9. However, the diameter of the TiO2 imprinted from the same part is 130 ± 4 nm and the height is 815 nm, so the HAR is 6.3. Compared with NOA imprinting, the measured shrinkage rate of the nanoparticle column with respect to the master is less than 10% in diameter, but the shrinkage in height is 26%. This shrinkage is due to the solvent-assisted imprinting technique, where solvent-dispersed nanoparticles fill the PDMS stamp by capillary force, and then the solvent diffuses through the stamp, resulting in an underfilled mold volume. To achieve the dimensions of a specific imprinted characteristic feature, a master mold can be manufactured including a shrinkage compensation component.

[0099] The imprinted HAR TiO2 column shows the same column area after 50 cycles of ALD of TiO2. No obvious change in the structure is observed, indicating that the deposited TiO2 does not simply deposit on the surface. One of the changes observed in the HAR column before and after ALD is a slight increase in HAR after ALD. This is likely due to gentle shrinkage (250 °C) due to heating during ALD.

[0100] Regulation of all-inorganic TiO2 films Achieving the highest possible refractive index is often desired in many applications, but the ability to adjust the refractive index over a certain range of values opens the door to situations that require precise refractive index tailoring, matching, and / or grading. A TiO2 nanoparticle film was spin-coated for 5 seconds and then dried on a hot plate at 60 °C for 2 minutes to prepare the film. This method mimics the conditions used for nanopattern generation by NIL using a solvent. Note that this gives a slightly lower starting refractive index value (ALD at 0 cycles). This may be due to differences in nanoparticle packing. The spin-coated film until the solvent is completely removed is more densely packed and results in a slightly higher value (1.82 vs. 1.77). The refractive index (n D ) increases linearly in direct proportion to the number of ALD cycles between 2 and 15. This allows access to intermediate refractive index values and can thus be used for the manufacture of gradient index (GRIN) lenses. This method of adjustability has the advantage that it can be completely inorganic and composed of a single material. In many applications where durability and UV stability are of interest, all-inorganic materials are desirable. Furthermore, by using only TiO2, the compatibility between the two materials is ensured.

[0101] The terms and expressions employed are used for illustrative and not for limiting purposes, and it should be noted that the use of such terms and expressions is not intended to exclude equivalents of the features illustrated and described or portions thereof, and various modifications are possible within the scope of the embodiments of the present invention. Accordingly, while the present invention has been specifically disclosed by way of specific embodiments and optional features, it is to be understood that improvements and variations of the technical idea of the present disclosure can be made by those skilled in the art, and that such improvements and variations are within the scope of the embodiments of the present invention.

[0102] Enumeration of Embodiments Exemplary embodiments are presented below, but the numbering should not be construed as specifying a level of importance.

[0103] Embodiment 1 provides a method for manufacturing a textured surface, which comprises arranging a template on a substrate and planarizing the template with nanoparticle ink. Embodiment 2 provides the method of Embodiment 1, further comprising imprinting the template with a mold including a plurality of feature elements penetrating through the template to form an imprinted template.

[0104] Embodiment 3 provides the method of any one of Embodiments 1 or 2, wherein the template comprises a crosslinked material. Embodiment 4 provides the method of any one of Embodiments 1 to 3, wherein the template comprises a polymer resin.

[0105] Embodiment 5 provides the method of Embodiment 2, wherein the imprinting comprises imprint lithography without residue. Embodiment 6 provides the method of Embodiment 2, wherein the imprinting generates imprinted feature elements on the template that are substantially corresponding in shape and position to the feature elements on the mold.

[0106] Embodiment 7 provides the method of Embodiment 6, wherein the nanoparticle ink substantially fills the imprinted feature elements of the template. Embodiment 8 provides the method of any one of Embodiments 1 to 8, wherein the nanoparticle ink comprises indium tin oxide, titanium dioxide, aluminum oxide, silicon dioxide, metal oxides, metal nitrides, metal carbides, metal oxynitrides, metal oxycarbides, silicon oxide, metal borides, metal silicides, or combinations thereof.

[0107] Embodiment 9 provides the method of any one of Embodiments 1 to 9, further comprising first annealing the imprinted template and the substrate. Embodiment 10 provides the method of Embodiment 8, wherein the first annealing comprises heating, microwave irradiation, visible light irradiation, infrared irradiation, and ultraviolet irradiation.

[0108] Embodiment 11 provides a method according to any one of Embodiments 1 to 10, further comprising removing the template from the substrate. Embodiment 12 provides a method according to Embodiment 11, wherein the removing includes dissolution, calcination, microwave irradiation, visible light irradiation, infrared irradiation, or ultraviolet irradiation.

[0109] Embodiment 13 provides a method according to Embodiment 12, further comprising second annealing the substrate and the template. Embodiment 14 provides a method according to any one of Embodiments 2 to 13, wherein the feature element has an aspect ratio of height:width of from about 2:1 to about 10:1.

[0110] Embodiment 15 provides a method according to any one of Embodiments 2 to 14, wherein the feature elements are arranged in a periodic pattern. Embodiment 16 provides a method according to any one of Embodiments 2 to 15, wherein the feature elements are arranged randomly.

[0111] Embodiment 17 provides a method according to any one of Embodiments 2 to 16, wherein the mold includes at least one substantially flat surface, and at least one of the plurality of feature elements has a side surface forming an acute angle with the mold.

[0112] Embodiment 18 provides a method according to Embodiment 17, wherein the acute angle ranges from about 10 degrees to about 89 degrees. Embodiment 19 provides a method for manufacturing a textured surface, comprising flattening an engraved template with nanoparticle ink to form a transfer printing master, and bringing the transfer printing master into contact with a substrate.

[0113] Embodiment 20 provides a method according to Embodiment 19, further comprising disposing a template on a first substrate before the flattening, and engraving the template with a mold including a plurality of feature elements penetrating through the template to form the engraved template.

[0114] Embodiment 21 provides a method according to any one of Embodiments 19 or 20, further comprising removing the transfer printing master and providing a plurality of feature elements disposed on a second substrate.

[0115] Embodiment 22 provides a method according to any one of Embodiments 19 to 21, wherein the surface of the template includes a hard coat. Embodiment 23 provides a method according to Embodiment 20, wherein the printed template includes a crosslinked material.

[0116] Embodiment 24 provides a method according to any one of Embodiments 19 to 23, wherein the template includes a polymer resin. Embodiment 25 provides a method according to any one of Embodiments 20 to 24, wherein the printing includes imprint lithography without residues.

[0117] Embodiment 26 provides a method according to any one of Embodiments 20 to 25, wherein the printing generates a printed feature element on the template having a shape and position that substantially correspond to the feature element on the mold.

[0118] Embodiment 27 provides a method according to Embodiment 26, wherein the nanoparticle ink substantially fills the printed feature elements of the printed template. Embodiment 28 provides a method according to any one of Embodiments 19 to 27, wherein the nanoparticle ink includes indium tin oxide (ITO), titanium dioxide, aluminum oxide, silicon dioxide, metal oxides, metal nitrides, metal carbides, metal oxynitrides, metal oxycarbides, metal borides, metal silicides, or combinations thereof.

[0119] Embodiment 29 provides a method according to any one of Embodiments 19 to 28, further comprising annealing the substrate and the template. Embodiment 30 provides the method of Embodiment 29, wherein the annealing includes heating, microwave irradiation, visible light irradiation, infrared irradiation, and ultraviolet irradiation.

[0120] Embodiment 31 provides the method of any one of Embodiments 19 to 30, wherein the contacting includes a sheet-type or roll-to-roll transfer process. Embodiment 32 provides the method of any one of Embodiments 21 to 31, wherein the removing includes dissolution, calcination, microwave irradiation, visible light irradiation, infrared irradiation, or ultraviolet irradiation.

[0121] Embodiment 33 provides an article including a textured surface formed by the method of any one of Embodiments 1 to 32. Embodiment 34 provides the article of Embodiment 33, wherein the article includes a lens, a flat lens, a display, a flexible display, a touch panel, a sensor surface, a shielding foil, or a blazed diffraction grating.

[0122] Embodiment 35 provides an article including a textured surface formed by the method of any one of Embodiments 19 to 34. Embodiment 36 provides the article of Embodiment 35, wherein the article includes a lens, a flat lens, a display, a flexible display, a touch panel, a sensor surface, a shielding foil, or a blazed diffraction grating.

[0123] Embodiment 37 provides a method for manufacturing a textured surface, which includes placing a template on a substrate, imprinting the template with a mold including a plurality of feature elements penetrating the template to form an imprinted template, planarizing the imprinted template with nanoparticle ink, annealing the nanoparticle ink, and removing the imprinted template. The imprinting generates imprinted feature elements on the template that are substantially corresponding in shape and position to the feature elements on the mold. The nanoparticle ink substantially fills the imprinted feature elements of the template. The nanoparticle ink includes indium tin oxide, titanium dioxide, aluminum oxide, silicon dioxide, metal oxides, metal nitrides, metal carbides, metal oxynitrides, metal oxycarbides, silicon oxide, metal borides, metal silicides, or combinations thereof.

[0124] Embodiment 38 provides a method for manufacturing a textured surface, which includes placing a template on a first substrate, imprinting the template with a mold including a plurality of feature elements penetrating the template to form an imprinted template, planarizing the imprinted template with nanoparticle ink to form a transfer printing master, annealing the nanoparticle ink, contacting the transfer printing master with a second substrate, and removing the transfer printing master to provide a plurality of feature elements disposed on the second substrate. The imprinting generates imprinted feature elements on the template that are substantially corresponding in shape and position to the feature elements on the mold. The nanoparticle ink substantially fills the imprinted feature elements of the template. The nanoparticle ink includes indium tin oxide, titanium dioxide, aluminum oxide, silicon dioxide, metal oxides, metal nitrides, metal carbides, metal oxynitrides, metal oxycarbides, silicon oxide, metal borides, metal silicides, or combinations thereof.

[0125] Embodiment 39 provides a method of Embodiment 38, which includes performing at least one cycle of atomic layer deposition (ALD) that deposits a first reactant and a second reactant on the printed feature element, wherein the first reactant includes MX y , MR y , M(NR) y , M(OR) y , MX y R z , MX y (NR) z , MX y (OR) z , MCp2, or a combination thereof, the second reactant includes water, y and z are each independently an integer from 2 to 8, M is a metal, each X is independently F, Cl, Br, or I, each R is independently hydrogen or a substituted or unsubstituted C 1-20 alkyl, and Cp is a substituted or unsubstituted cyclopentadienyl.

[0126] Embodiment 40 provides a method of Embodiment 20, which includes performing at least one cycle of atomic layer deposition (ALD) that deposits a first reactant and a second reactant on the printed feature element, wherein the first reactant includes MX y , MR y , M(NR) y , M(OR) y , MX y R z , MX y (NR) z , MX y (OR) z , MCp2, or a combination thereof, the second reactant includes water, y and z are each independently an integer from 2 to 8, M is a metal, each X is independently F, Cl, Br, or I, each R is independently hydrogen or a substituted or unsubstituted C 1-20 alkyl, and Cp is a substituted or unsubstituted cyclopentadienyl.

[0127] Embodiment 41 provides a method of Embodiment 40, wherein the ALD fills pores of the feature element with TiO2. Embodiment 42 provides the method of Embodiment 41, wherein after the characteristic element is heated or exposed at a temperature of about 200°C to 1000°C, the characteristic element has a shrinkage of about 1% to 15%.

[0128] Embodiment 43 provides the method of Embodiment 42, wherein after the characteristic element is heated or exposed at a temperature of about 200°C to 1000°C, the characteristic element has a refractive index of about 1.2 to 4.0.

[0129] Embodiment 44 provides an article, the article comprising a surface with a plurality of characteristic elements protruding therefrom, and the height:width aspect ratio of the characteristic elements being from about 2:1 to about 10:1. Embodiment 45 provides the article of Embodiment 44, wherein the characteristic elements are arranged in a periodic pattern.

[0130] Embodiment 46 provides the article of any one of Embodiments 44 or 45, wherein the characteristic elements are arranged randomly. Embodiment 47 provides the article of any one of Embodiments 44 to 46, wherein at least one of the plurality of characteristic elements has a side surface, and the side surface forms an acute angle with the surface.

[0131] Embodiment 48 provides the article of Embodiment 47, wherein the acute angle ranges from about 10 degrees to about 89 degrees. Embodiment 49 provides the article of any one of Embodiments 44 to 48, wherein the plurality of characteristic elements independently have a refractive index of about 1.2 to 4.0.

[0132] Embodiment 50 provides the article of Embodiment 49, wherein after the characteristic element is heated or exposed to light at a temperature of about 200°C to 1000°C, the characteristic element independently has a refractive index of about 1.2 to about 4.0.

[0133] Embodiment 51 provides an article according to any one of Embodiments 44 to 50, wherein the article includes a lens, a display, a flexible display, a touch panel, a sensor surface, a shielding foil, a metalens, a light field display, a flat lens, or a blazed diffraction grating.

[0134] Embodiment 52 provides an article according to any one of Embodiments 44 to 51, wherein the article is optically transparent. Embodiment 53 provides an article according to Embodiment 52, wherein the article is optically transparent to electromagnetic radiation in the range of from about 400 nm to about 1400 nm.

[0135] Embodiment 54 provides an article according to either Embodiment 52 or 53, wherein the article is optically transparent to electromagnetic radiation in the range of from about 400 nm to about 700 nm. Embodiment 55 provides an article according to any one of Embodiments 52 to 54, wherein the article is optically transparent to electromagnetic radiation exceeding 905 nm.

[0136] Embodiment 56 provides an article according to any one of Embodiments 44 to 55, wherein the article is a virtual reality device or an augmented reality device. Embodiment 57 provides an article according to any one of Embodiments 44 to 56, wherein the article is a metalens or a flat lens.

[0137] Embodiment 58 includes disposing nanoparticle-based ink on a substrate, imprinting the ink with a mold including a plurality of feature elements to obtain a textured surface, and performing atomic layer deposition (ALD) including depositing a first reactant and a second reactant on the textured surface for at least one cycle, wherein the first reactant is MX y , MR y , M(NR) y , M(OR)y, MX y R z , MX y (NR) z , MX y (OR) z, MCp2, or a combination thereof, and the imprinting generates an imprinted feature element on the substrate whose shape and position substantially correspond to the feature element on the mold. The nanoparticle ink substantially fills the feature element of the mold to generate the feature element. The nanoparticle ink includes indium tin oxide, titanium dioxide, aluminum oxide, silicon dioxide, metal oxide, metal nitride, metal carbide, metal oxynitride, metal oxycarbide, silicon oxide, metal boride, metal silicide, or a combination thereof. The second reactant includes water, y and z are each independently an integer from 2 to 8, M is a metal, each X is independently F, Cl, Br, or I, and each R is independently hydrogen or a substituted or unsubstituted C 1-20 alkyl, and Cp is a substituted or unsubstituted cyclopentadienyl, and provides a method for manufacturing a textured surface.

[0138] Embodiment 59 provides an article formed according to the method of Embodiment 58. Embodiment 60 provides an article of any one of Embodiments 58 or 59, wherein the article comprises a surface including a plurality of feature elements protruding therefrom, and the height:width aspect ratio of the feature elements is from about 2:1 to about 10:1.

[0139] Embodiment 61 provides an article of Embodiment 60, wherein the feature elements are arranged in a periodic pattern. Embodiment 62 provides an article of Embodiment 60, wherein the feature elements are randomly arranged.

[0140] Embodiment 63 provides an article of any one of Embodiments 60 to 62, wherein at least one of the plurality of feature elements has a side surface, and the side surface forms an acute angle with the surface. Embodiment 64 provides an article of Embodiment 63, wherein the acute angle ranges from about 10 degrees to about 89 degrees.

[0141] Embodiment 65 provides an article of Embodiment 64, wherein the plurality of feature elements independently have a refractive index of about 1.2 to 4.0. Embodiment 66 provides an article of Embodiment 65, wherein after the characteristic element is heated at a temperature of about 200°C to 1000°C or exposed to light, the characteristic element independently has a refractive index of about 1.2 to about 4.0.

[0142] Embodiment 67 provides an article of Embodiment 66, wherein the refractive index corresponds to a predetermined refractive index value. Embodiment 68 provides an article of Embodiment 66, which provides an article of Embodiment 67, wherein the refractive index is within 5 percent of the predetermined refractive index value.

[0143] Embodiment 69 provides an article of any one of Embodiments 60 - 68, wherein the article includes a lens, a display, a flexible display, a touch panel, a sensor surface, a shielding foil, a metalens, a light field display, a flat lens, or a blazed diffraction grating.

[0144] Embodiment 70 provides an article of any one of Embodiments 60 - 69, wherein the article is optically transparent. Embodiment 71 provides an article of any one of Embodiments 60 - 70, wherein the article has a gradient of refractive index values.

Claims

1. An article comprising a textured surface, said textured surface comprising a plurality of feature elements protruding in a periodic pattern or randomly arranged, said feature elements comprising nanoparticles, said textured surface comprising a plurality of nanopores at least partially filled with a deposited material of atomic layer deposition of 2 to 5000 cycles, said plurality of feature elements independently having a height:width aspect ratio of from about 2:1 to about 10:1 and a refractive index of from about 1.2 to 4.

0.

2. The article of claim 1, wherein said plurality of feature elements independently have a height:width aspect ratio of from about 5:1 to about 10:

1.

3. The article of claim 1, wherein said plurality of feature elements independently have a height:width aspect ratio of from about 6:1 to about 10:

1.

4. The article of claim 1, wherein said plurality of feature elements are arranged in a periodic pattern.

5. The article of claim 1, wherein said plurality of feature elements are arranged randomly.

6. The article of claim 1, wherein at least one of said plurality of feature elements has a side surface that forms an acute angle with said textured surface.

7. The article of claim 6, wherein said acute angle is from about 10 degrees to about 89 degrees.

8. The article of claim 1, wherein said plurality of feature elements independently have a refractive index of from about 1.25 to 2.

4.

9. The article of claim 1, wherein said plurality of feature elements independently have a refractive index of from about 1.6 to 2.

6.

10. The article of claim 1, wherein said textured surface has a gradient of refractive index values.

11. The article of claim 1, wherein said plurality of feature elements independently have a height:width aspect ratio of from about 6:1 to about 10:1 and a refractive index of from about 1.25 to 2.

4.

12. The article of claim 1, wherein said plurality of feature elements further comprise a plurality of nanoparticles.

13. The article of claim 1, wherein said textured surface is optically transparent to visible light.

14. The article of claim 1, wherein said article is optically transparent to electromagnetic radiation in the range of about 400 nm to about 1400 nm.

15. The article of claim 1, wherein said article is optically transparent to electromagnetic radiation in the range of about 400 nm to about 700 nm.

16. The article of claim 1, wherein said article is optically transparent to electromagnetic radiation above 905 nm.

17. The article according to claim 1, wherein the article comprises a meta surface, a lens, a display, a flexible display, a touch panel, a sensor surface, a shielding foil, a metalens, a light field display, a flat lens, or a blazed diffraction grating.

18. The article according to claim 1, wherein the article is a virtual reality device or an augmented reality device.

19. The article according to claim 1, wherein the article is a metalens or a flat lens.

20. The article according to claim 1, wherein the characteristic element does not contain an organic material.

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