Structured film and optical article comprising a structured film

Abstract

An optical article comprising a waveguide and a structured film. The structured film comprises: a polymer substrate; an etch barrier layer disposed on the polymer substrate; a structured layer comprising a plurality of engineered structures disposed on a side of the etch barrier layer opposite the polymer substrate; a planarization backfill layer disposed over the plurality of engineered structures to define a substantially planar major surface of the planarization backfill layer having a surface roughness Ra; and an adhesive layer disposed on the substantially planar surface of the planarization backfill layer and bonding the structured film to the waveguide. A refractive index difference between the planarization backfill layer and the structured layer is at least 0.25 for at least a first wavelength W1 in a range from 400 nm to 2500 nm. The adhesive layer has an average thickness ta, where Ra < ta < 1 / 4 W1.

Description

Background Technology

[0001] Structured products (such as nanostructured products) can be used in a variety of applications, including optical applications (such as optical metasurface applications). Summary of the Invention

[0002] This specification relates in its entirety to structured films and optical products including structured films.

[0003] In some aspects of this specification, an optical article is provided. The optical article includes a waveguide and a structured film. The structured film includes: a polymer substrate; an etch barrier layer disposed on the polymer substrate; a structured layer including a plurality of engineered structures disposed on a side of the etch barrier layer opposite to the polymer substrate; a planarization backfill layer disposed over the plurality of engineered structures to define a substantially flat main surface of the planarization backfill layer having a surface roughness Ra; and an adhesive layer disposed on the substantially flat main surface of the planarization backfill layer and bonding the structured film to the waveguide. For at least a first wavelength W1 in the range of 400 nm to 2500 nm, the refractive index difference between the planarization backfill layer and the structured layer is at least 0.25. The adhesive layer has an average thickness ta, wherein Ra <ta<1 / 4W1。

[0004] In some aspects of this specification, a structured film is provided. The structured film includes: a polymer substrate; an etch barrier layer disposed on the polymer substrate; a structured layer including a plurality of engineered structures disposed on a side of the etch barrier layer opposite to the polymer substrate; a planarization backfill layer disposed over the plurality of engineered structures to define a substantially flat main surface of the planarization backfill layer having a surface roughness Ra; and an adhesive layer disposed on the substantially flat main surface of the planarization backfill layer. The engineered structures may be tilted relative to the etch barrier layer. For at least a first wavelength W1 in the range of 400 nm to 2500 nm, the refractive index difference between the planarization backfill layer and the structured layer is at least 0.25. The adhesive layer has an average thickness ta, wherein Ra <ta<1 / 4W1。

[0005] In some aspects of the present specification, an optical article is provided that includes a waveguide and a structured film disposed on a major surface of the waveguide. The structured film includes: an etch stop layer; a structured layer disposed on the etch stop layer and including a plurality of engineered structures; a planarizing backfill layer disposed over the plurality of engineered structures to define a substantially unstructured major surface of the planarizing backfill layer having a surface roughness Ra; and an adhesive layer disposed on the substantially unstructured major surface of the planarizing backfill layer. For at least a first wavelength W1 in the range of 400 nm to 2500 nm, the refractive index difference between the planarizing backfill layer and the structured layer is at least 0.25. The adhesive layer bonds the structured film to the major surface of the waveguide and has an average thickness ta, where Ra < ta < 1 / 4W1. The engineered structures may be inclined with respect to the etch stop layer.

[0006] In some aspects of the present specification, a structured film is provided. The structured film includes: a polymer substrate; an etch stop layer; a dynamic release layer disposed between the polymer substrate and the etch stop layer; a structured layer including a plurality of engineered structures disposed on a side of the etch stop layer opposite the dynamic release layer; a planarizing backfill layer disposed over the plurality of engineered structures to define a substantially flat major surface of the planarizing backfill layer having a surface roughness Ra; and an adhesive layer disposed on the substantially flat major surface of the planarizing backfill layer. For at least a first wavelength W1 in the range of 400 nm to 2500 nm, the refractive index difference between the planarizing backfill layer and the structured layer is at least 0.25. The adhesive layer has an average thickness ta, where Ra < ta < 1 / 4W1. The dynamic release layer is adapted to facilitate separation of the polymer substrate and the etch stop layer upon activation.

[0007] These and other aspects will become apparent from the following detailed description. However, in no case should this brief summary be construed as limiting the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figures 1 to 3 is a schematic cross-sectional view of an optical article according to some embodiments, the optical article including a waveguide and a structured film having a polymer substrate.

[0009] Figures 4A to 4B Schematically illustrates removal of the polymer substrate from the optical article according to some embodiments.

[0010] Figures 5A to 5C Schematically illustrates removal of the polymer substrate from an optical article including a release layer according to some embodiments.

[0011] Figures 6A to 6C This is a schematic cross-sectional view of an optical article according to some embodiments, the optical article including a waveguide and a structured film having a tilted structure.

[0012] Figures 7A to 7C The process for fabricating structured membranes according to some embodiments is illustrated schematically.

[0013] Figure 8 It is a schematic cross-sectional view showing light incident on one or more layers according to some embodiments. Detailed Implementation

[0014] Reference is made in the following description to the accompanying drawings, which form part of the invention and illustrate various embodiments by way of example. The drawings are not necessarily drawn to scale. It should be understood that other embodiments may be conceived and practiced without departing from the scope or spirit of this specification. Therefore, the following detailed description should not be considered limiting.

[0015] Nanostructured articles can be formed by patterning functional materials. Patterning of functional materials can be achieved by depositing a uniform layer of functional material on a substrate (e.g., a waveguide) and then using a photolithographic patterning step to create a pattern in the material. Other methods for forming nanostructured articles are described, for example, in international patent applications published WO 2020 / 095258 (VanLengerich et al.) and WO 2020 / 097319 (Wolk et al.).

[0016] According to some embodiments of this specification, a structured film is provided that can be used to apply structures (e.g., nanostructures) onto a substrate without the series of steps used in typical photolithography patterning processes. For example, the structured film can be significantly larger than the semiconductor wafer format used in conventional nanoimprint lithography (NIL) batch processes or the display glass substrate typically used in large-format NIL or roll-to-roll NIL. In some embodiments, the structured film has a maximum dimension, for example, greater than 100 mm, 200 mm, 300 mm, 450 mm, or 600 nm. In some embodiments, the structured film has a maximum dimension, for example, greater than 4 μm, or greater than 5 μm, or greater than 10 μm, or greater than 50 μm, or greater than 100 μm. The structured film can be fabricated in a continuous roll-to-roll process. In some embodiments, a roll of the structured film is provided. In some embodiments, the roll is converted into a sheet form.

[0017] For example, the structured film may include a low refractive index layer that separates the structured layer from the polymer substrate, or the polymer substrate included in the structured film may be removed after the structured film is applied to the waveguide. The structured film may be designed to create, for example, a surface relief grating (SRG) or an equivalent form of an optical metasurface on the waveguide without using a series of photolithographic patterning steps used in typical SRG patterning processes.

[0018] Figures 1 to 3 are schematic cross-sectional views illustrating exemplary optical articles 100, 200, and 300, respectively. In some embodiments, the optical article 100 (and correspondingly 200, 300) includes a waveguide 190 and a structured film 150 (and correspondingly 250, 350). The structured film 150 (and correspondingly 250, 350) includes: a polymer substrate 130; an etch stop layer 137 disposed on the polymer substrate 130; a structured layer 110 (and correspondingly 210, 310) that includes a plurality of engineered structures 129 (and correspondingly 229, 329) disposed on a side of the etch stop layer 137 opposite the polymer substrate 130; a planarization backfill layer 115 (and correspondingly 215, 315) disposed over the plurality of engineered structures 129 (and correspondingly 229, 329) to define a substantially flat major surface 121 (and correspondingly 221, 321) of the planarization backfill layer 115 (and correspondingly 215, 315) having a surface roughness Ra (see, for example Figures 7A to 7C ); and an adhesive layer 140 disposed on the substantially flat major surface 121 (and correspondingly 221, 321) of the planarization backfill layer 115 (and correspondingly 215, 315) and bonding the structured film to the waveguide 190. For at least a first wavelength W1 in the range of 400 nm to 2500 nm or other ranges described elsewhere herein, the refractive index difference between the planarization backfill layer 115 (and correspondingly 215, 315) and the structured layer may be at least 0.25. The adhesive layer 140 has an average thickness ta, where Ra < ta < 1 / 4W1. The surface roughness Ra is the mean deviation surface roughness. The surface roughness Ra may be measured in accordance with, for example, the ISO 4287:1997 standard.

[0019] When any deviation from planarity in the transverse direction (e.g., in the xy plane) is substantially greater than the average height t2 (e.g., 100 times or 1000 times t2), the main surface 121 (correspondingly 221, 321) can be considered substantially flat. In some embodiments, the planarized surface has a planarization amount (P) of more than 50%, or more preferably more than 75%, and most preferably more than 90%, wherein the planarization amount is given by P = (1 - (a1 / a2)) * 100%, where a1 is the undulation height of the surface layer (e.g., the planarization backfill layer) and a2 is the feature height of the feature covered by the surface layer, as further disclosed in P. Chiniwalla, IEEE Trans. Adv. Packaging, 24(1), 2001, 41).

[0020] For a given application, the adhesive layer 140 may have an average thickness within a suitable range. In some embodiments, the average thickness ta of layer 140 is less than 250 nm, or less than 200 nm, or less than 150 nm, or less than 100 nm, or less than 75 nm, or less than 50 nm, or less than 40 nm, or less than 30 nm. In some such embodiments, or in others, the average thickness ta is at least 5 nm, or at least 10 nm, or at least 15 nm. In some embodiments, the average thickness ta is selected to be less than 1 / 4 of the wavelength of interest. For example, for visible light, it may be preferred that the average thickness is less than 100 nm or substantially less than 100 nm (e.g., less than 50 nm), while for near-infrared light, the average thickness may be, for example, up to 250 nm, or even greater when a longer wavelength is of interest. For example, a thickness less than 1 / 4 of the wavelength of interest allows the resulting structure formed in one or more unstructured layers to be coupled to an evanescent wave in a waveguide. This may allow the resulting structure to be used, for example, as a surface undulation grating (SRG). As used herein, the term SRG includes cases where a grating is embedded in a material with a different refractive index. For example, this structure can be used for optical input coupling and / or output coupling (e.g., to augmented reality waveguide elements). Alternatively or additionally, the resulting structure can be used for exit pupil expansion in augmented reality waveguide elements, such as as a light distribution element, orthogonal pupil expander, or redirection element. An exemplary example of the use of SRGs in image-preserving waveguides can be found, for example, in International Patent Application Publication WO 2019 / 195186 (Peroz et al.).

[0021] Layer 140 may be a polymer or monomer adhesive layer and / or an optically clear adhesive layer. Suitable optically clear adhesives include, for example, those available from Norland Products Inc. (Cranbury, NJ). Other suitable adhesives include thermosetting materials, such as those available under the trade name CYCLOTENE from Dow Chemical Company (Midland, MI). Still other suitable adhesives include thermally activated adhesives, such as those available under the trade name KRATON from KRATON Polymers (Huston, TX). Suitable adhesive layers, including thin adhesive layers (e.g., less than 50 nm thick), are described in, for example, the following U.S. patents: U.S. Patent 7,521,727 (Khanarian et al.); 7,53,419 (Camras et al.); U.S. Patent 6,709,883 (Yang et al.); and U.S. Patent 6,682,950 (Yang et al.).

[0022] The polymer substrate 130 may be, for example, a polyethylene terephthalate (PET) film or a polycarbonate film, which may be dimensionally stable (e.g., heat-set). Other suitable materials for the polymer substrate 130 include, for example, other polyesters or copolyesters, polyurethanes, polymethyl methacrylate, polystyrene, polyimide, polyethylene naphthalate, polypropylene, and cyclic olefin copolymers. In some embodiments, the polymer substrate has a low birefringence (the maximum in-plane refractive index difference at a first wavelength W1 multiplied by the layer thickness). In some embodiments, the retardation is less than 50 nm, or less than 10 nm, or less than 5 nm, or less than 1 nm.

[0023] For example, waveguide 190 may be a glass waveguide or a polymer (e.g., polymethyl methacrylate) waveguide. In some embodiments, waveguide 190 is an image-preserving waveguide (e.g., a waveguide that preserves the image when light containing an image (e.g., light from a display) propagates along the waveguide and is then extracted from it). In some embodiments, the waveguide combiner includes a structure that defines an optical metasurface input and / or output coupler for the waveguide and a structured film. Waveguide combiners are described, for example, in: Kress, “Optical waveguide combiner for AR headphones: features and limits,” Proc. SPIE, 11062, Digital Optical Technologies, 2019, 110620J (July 16, 2019); doi: 10.1117 / 12.2527680.

[0024] In some embodiments, the engineered structure 129 has length and width in orthogonal directions (e.g., the x and y directions), each orthogonal to the thickness direction (z direction). In some embodiments, the plurality of engineered structures 129 (correspondingly 229, 329) are or include a plurality of nanostructures. A nanostructure is a structure having at least two orthogonal dimensions (e.g., at least two of height, length, and width) in the range of about 1 nm to about 1000 nm. An engineered structure is a structure intentionally fabricated with a predetermined geometry (e.g., predetermined length, width, and height). Some representative engineered structure (e.g., engineered nanostructure) shapes include, but are not limited to, rectangular, triangular, and trapezoidal prisms, fins, cylindrical and truncated conical struts, and other such shapes. In some embodiments, the engineered structure has an average aspect ratio (height divided by length or width or maximum lateral (orthogonal to height) dimension) of, for example, at least 0.1, or at least 0.2, or at least 0.5, or at least 1, or at least 2, or at least 5, or at least 10. Engineered structures can be regular or irregular (e.g., pseudo-random distribution, where the structure may appear to be randomly arranged but is made by a deterministic process below) in terms of spacing, orientation, and / or shape placement, which may depend on the functionality and manufacturability of the application.

[0025] In some embodiments, the leveling backfill layer 115 (correspondingly 215, 315) includes a residual layer 142 (correspondingly 242, 342) located between the adhesive layer 140 and the structured layer 110 (correspondingly 210, 320). The residual layer can be described as the portion of the backfill layer above the top of the structured layer (in the positive z-direction). In some embodiments, the ratio of the average (unweighted average) thickness t1 of the residual layer 142 to the average height t2 of the plurality of engineered structures is less than 1, or less than 0.5, or less than 0.3, or less than 0.25. In some embodiments, t1 / t2 is, for example, in the range of 0.001 to 0.5. In some embodiments, the maximum thickness (t1+t2) of the leveling backfill layer is no more than 2 times, or no more than 1.5 times, or no more than 1.3 times the average height t2 of the plurality of engineered structures. In some embodiments, the thickness of the residual layer 142 is less than 100 nm, or less than 50 nm, or less than 30 nm, or less than 20 nm, or less than 10 nm.

[0026] The main surface 121 (correspondingly 221, 321) can be considered substantially unstructured when any structure that may exist on the surface has a height that is substantially less than the average height t2 (e.g., less than 20%, or less than 10%, or less than 5%, or less than 3% of the average height t2). The main surface 121 (correspondingly 221, 321) can be considered substantially flat when any deviation from planarity on a length scale that is substantially greater than the average height t2 (e.g., 100 times or 1000 times t2) in the transverse direction (e.g., in the xy plane) is substantially less than the average height t2 (e.g., less than 20%, or less than 10%, or less than 5%, or less than 3% of the average height t2).

[0027] In some embodiments, the polymer substrate 130 is releasably attached to the etch barrier layer 137 and is removed after the structured film is bonded to the waveguide (see, for example...). Figures 4A to 6C Alternatively, in some embodiments, after the structured film is bonded to the waveguide, the polymer substrate 130 is removed by dissolving the layer in acid. In either case, after the polymer substrate 130 has been removed, the etch barrier layer 137 may optionally be removed via, for example, reactive ion etching.

[0028] When two layers can be separated from each other with little or no damage to either layer (e.g., the damage is small enough that it is not easily visible to the naked eye of someone with 20 / 20 vision), the two layers are releasably attached to each other. The releasably attached first and second layers include a third layer disposed between the first and second layers, wherein the third layer is adapted to facilitate separation of the first and second layers (e.g., the third layer may be adapted to separate the first and second layers or to separate from at least one of the first and second layers). The third layer may be adapted to facilitate separation of the first and second layers only after the third layer is activated (e.g., via radiation, chemical activation, or thermal activation). For example, the third layer may be a dynamically separating layer. A dynamically separating layer is a layer that can change from a first state to at least a second state (e.g., by activating the separating layer via radiation), wherein the layer provides higher adhesion to at least one adjacent layer in the first state and lower adhesion to at least one adjacent layer in the second state. For example, the dynamic separation layer can be a photo-induced stress mode release layer (e.g., a polymer layer that can be crosslinked or further crosslinked upon irradiation, such that the increase in crosslinking generates stress that promotes release from adjacent layers) and / or a photothermal conversion (LTHC) layer.

[0029] The structured film can be configured such that the polymer substrate 130 can be releasably attached to the etch barrier layer 137 by including a segmentation layer between the polymer substrate 130 and the etch barrier layer 137, or by including a dynamic separation layer between the polymer substrate 130 and the etch barrier layer 137 and activating (e.g., via irradiation) the dynamic separation layer. The segmentation layer is a static separation layer, which can be, for example, a low surface energy layer, or a layer co-extruded with the polymer substrate 130 and weakly adhered to the polymer substrate 130 (e.g., Figure 5A The separation layer 160' shown is, according to some embodiments, as generally described, such as in, U.S. Patent 9,415,561 (Lindquist et al.). The dynamic separation layer (e.g., an LTHC layer) may comprise multiple sublayers. Suitable dynamic separation layers include carbon black nanocomposites, thin optically absorbing metal (e.g., aluminum, titanium, or chromium) layers, and light-absorbing optical cavities, such as those defined by thin (e.g., 10 nm to 30 nm) metal (e.g., aluminum, titanium, or chromium) layers separated by polymer layers (such as acrylate layers). For example, the dynamic separation layer may be formed from 3M photothermal conversion release coating (LTHC) ink (available from 3M Company, St. Paul, MN). Other suitable dynamic separation layers include, for example, the LTHC layers described in U.S. Patents 7,977,864 (Bellmann et al.) and 7,670,450 (Lamansky et al.).

[0030] In some embodiments, an additional layer 160 is disposed between the etch barrier layer 137 and the polymer substrate 130. This is in Figure 2 For example, this is schematically shown with respect to structured membrane 250, which may correspond to structured membrane 150 in addition to additional layer 160. Similarly, it may be optionally... Figure 3 An additional layer 160 is included between the etch barrier layer 137 and the polymer substrate 130 of the structured film 350. For example, the additional layer 160 may be a low-refractive-index layer, a separation layer, or a release layer. In some embodiments, the additional layer 160 is a dynamic release layer (e.g., a photothermal conversion (LTHC) layer) disposed between the etch barrier layer 137 and the polymer substrate 130. In some such embodiments, an additional polymer layer is disposed between the etch barrier layer 137 and layer 160 (see, for example...). Figures 5B to 5C In some embodiments, a dynamic separation layer is included, and a low-refractive-index layer is included between the dynamic separation layer and the etch barrier layer 137. In some embodiments, the dynamic separation layer 160 is adapted to facilitate separation of the polymer substrate and the etch barrier layer upon activation. Activation may be performed via, for example, radiation. Suitable radiation may include radiation of one or more wavelengths, including visible light, infrared radiation, or ultraviolet radiation from a laser, light bulb, or other radiation source. Available radiation conditions are described, for example, in U.S. Patent 7,977,864 (Bellmann et al.).

[0031] Figures 4A to 5C Various methods for removing the polymer substrate 130 are schematically illustrated. Figures 4A to 4B In this embodiment, optical articles 100' and 100" may correspond to, for example, optical article 100. Optical article 100' is configured such that polymer substrate 130 is releasably attached to etch barrier layer 137. In this embodiment, and in some other embodiments, a separation interface exists between polymer substrate 130 and etch barrier layer 137, which can be created by a surface treatment applied to polymer substrate 130 prior to applying etch barrier layer 137 to polymer substrate 130. Optical article 100" is configured such that etch barrier layer 137 is releasably attached to layers 110 and 115. In this embodiment, and in some other embodiments, a separation interface exists between etch barrier layer 137 and layers 110 and 115, which can be created by, for example, providing layer 110' on etch barrier layer 137 (see...). Figure 7A The surface treatment applied to the etch barrier layer 137 prior to this was produced.

[0032] exist Figures 5A to 5C In this context, optical articles 200' and 200” can correspond to, for example, optical article 200. Figure 5AIn this embodiment, a polymer substrate is releasably attached to a release layer 160', which may be a static release layer (e.g., co-extruded with the polymer substrate 130) or a dynamic release layer. In this embodiment, and in some other embodiments, a separation interface exists between the polymer substrate 130 and the release layer 160', which may be created by co-extrusion of the polymer substrate 130 and the release layer 160', as generally described, for example, in U.S. Patent 9,415,561 (Lindquist et al.). Figure 5B In this embodiment, a dynamic separation layer 160” is disposed between the polymer substrate 130 and the etch barrier layer 137. An additional substrate layer 132 is disposed between the dynamic separation layer 160” and the etch barrier layer 137. For example, the additional substrate layer 132 may be a low refractive index layer (e.g., having a refractive index within the range described elsewhere herein for low refractive index layers). The dynamic separation layer 160” may be adapted to be releasably attached to the additional substrate layer 132 upon activation. In this embodiment, and in some other embodiments, upon activation, a separation interface exists between the dynamic separation layer 160” and the additional substrate layer 132, such as Figure 5C It is shown schematically in the diagram.

[0033] In some embodiments, the structured film 250 includes: a polymer substrate 130; an etch barrier layer 137; a dynamic separation layer 160 disposed between the polymer substrate and the etch barrier layer; a structured layer 210 including a plurality of engineered structures 229 disposed on the side of the etch barrier layer 137 opposite to the dynamic separation layer 160; a planarization backfill layer 215 disposed over the plurality of engineered structures 229 to define a substantially flat main surface 221 of the planarization backfill layer 215 having a surface roughness Ra; and an adhesive layer 140 having an average thickness ta disposed on the substantially flat main surface 221 of the planarization backfill layer 215. In some embodiments, the dynamic separation layer is adapted to promote separation of the polymer substrate 130 and the etch barrier layer 137 upon activation (e.g., via irradiation). For example, the dynamic separation layer 160 may be adapted to be released from the etch barrier layer 137 upon activation (e.g., via irradiation), or the dynamic separation layer 160 may be adapted to be released from an additional layer disposed between the etch barrier layer 137 and the dynamic separation layer upon activation (see example...). Figure 5C In some embodiments, for at least a first wavelength W1 in the range of 400 nm to 2500 nm or other ranges described elsewhere herein, the refractive index difference between the planarization backfill layer 215 and the structured layer 210 is at least 0.25. In some embodiments, Ra <ta<1 / 4W1。

[0034] In some embodiments, it is desirable to retain the polymer substrate 130 within the structured film. However, in some cases, it is desirable to have a layer (e.g., air or a low-refractive-index coating) with a lower refractive index than the polymer substrate 130 adjacent to the etch-blocking layer 137. Such layers may be included to improve optical confinement in the planarization backfill layer and the structured layer. In some embodiments, the additional layer 160 is a low-refractive-index unstructured layer. Suitable low-refractive-index layers include nanoporous coatings, dry gels and aerogels, perfluoropolyethers, TEFLON, CYTOP materials, hexafluoropropylene oxide (HFPO), or fluorene methacrylate. Available low-refractive-index layers are described, for example, in U.S. Patent 8,808,811 (Kolb et al.). In some embodiments, the additional layer 160 is a fluoropolymer layer. For example, for at least a first wavelength W1, the low-refractive-index layer may have a refractive index in the range of 1.1 to 1.45, or 1.15 to 1.4, or 1.2 to 1.35. In some embodiments, the low-refractive-index layer has a thickness of, for example, at least 50 nm, or at least 100 nm, or at least twice or at least five times t2. In some such embodiments, or in others, the low-refractive-index layer has a thickness of, for example, no more than 10 micrometers, or no more than 5 micrometers. In some embodiments, the structured film 250 includes an unstructured layer 160 disposed between the etch barrier layer 137 and the polymer substrate 130, wherein the refractive index difference between the planarization backfill layer 215 and the unstructured layer 160 is at least 0.2 or at least 0.25 for at least a first wavelength W1.

[0035] In some implementations, the engineered structure 129 or 229 is tilted relative to the etch barrier layer 137. Figure 3 This is a schematic cross-sectional view of an article 300 including a structured film 350 having engineered structures 329 inclined relative to an etch barrier layer 137. In some embodiments, the structured film 350 includes: a polymer substrate 130; an etch barrier layer 137 disposed on the polymer substrate 130; a structured layer 310 including a plurality of engineered structures 329 disposed on the side of the etch barrier layer 329 opposite to the polymer substrate 130, wherein the engineered structures 329 are inclined relative to the etch barrier layer 137; a planarization backfill layer 315 disposed over the plurality of engineered structures 137 to define a substantially flat main surface 321 having a surface roughness Ra; and an adhesive layer 140 having an average thickness ta disposed on the substantially flat main surface of the planarization backfill layer. In some embodiments, for at least a first wavelength W1 in the range of 400 nm to 2500 nm or other ranges described elsewhere herein, the refractive index difference between the planarization backfill layer 315 and the structured layer 310 is at least 0.25. In some embodiments, Ra <ta<1 / 4W1。

[0036] The engineered structure is tilted when a line passing through the center of the top (facing away from etch stop layer 137) and bottom (facing etch stop layer 137) of the structure forms an angle between 5 and 85 degrees with the etch stop layer 137. In the case of top and bottom facets, the center can be the centroid of the top and bottom of the structure. For example, the engineered structure 329 can be described as tilted when a line 341 passing through the centroid of the facet 343 facing the etch stop layer 137 and the centroid of the opposite facet 346 facing away from the etch stop layer 137, or in the case of a pointed engineered structure, forms an angle θ0 between 5 and 85 degrees with the etch stop layer 137. The tilted engineered structure may have opposite sidewalls forming angles θ1 and θ2 with the etch stop layer 137. Angles θ1 and θ2 are exterior angles (angles outside the structure 329). Angles θ0 and / or θ1 may be, for example, at least 45 degrees, or at least 50 degrees, and / or may be, for example, no more than 85 degrees, or no more than 80 degrees, or no more than 75 degrees. In some embodiments, angles θ0 and / or θ1 are, for example, in the range of 45 degrees to 85 degrees, or 50 degrees to 80 degrees. Angle θ2 may be about 180 degrees minus θ1, or may be different. In some embodiments, angle θ2 is, for example, in the range of 95 degrees to 135 degrees. In some embodiments, at least a majority (or at least 60%, or at least 80%, or at least 90%) of each engineered structure in the engineered structure has a sidewall defined with the etch barrier layer 137 at an outer angle θ1 in the range of 45 degrees to 85 degrees. In addition to the inclined engineered structure 329, the structured layer 310 may optionally include non-inclined structures. In some embodiments, at least 60%, or at least 80%, or at least 90% of all engineered structures defined in the structured layer 310 are tilted relative to the etch barrier layer 137.

[0037] In some implementations, the polymer substrate 130 is removed after the structured membrane 150, 250, or 350 has been bonded to the waveguide. Figures 6A to 6C This is a schematic cross-sectional view of an exemplary article, which can be formed by bonding a structured film to a waveguide 190 and then removing a polymer substrate 130. Figure 6A A structured membrane 351, which can be formed from a structured membrane 350 by removing a polymer substrate 130, is schematically shown. Similarly, structured membranes 250 and 250 can be obtained by removing a polymer substrate 130 and an additional layer 160 optionally used for structured membrane 150.

[0038] In some embodiments, optical article 301 (or Figures 6B to 6CThe 301', 301" depicted in the image include a waveguide 190 and a structured film 351 disposed on the main surface 191 of the waveguide 190. The structured film 351 includes: an etch barrier layer 137; a structured layer 310 disposed on the etch barrier layer 137 and including a plurality of engineered structures 329, wherein the engineered structures 329 are inclined relative to the etch barrier layer 137; and a planarization backfill layer 315 disposed above the plurality of engineered structures 329 to define a basic planarization backfill layer 315 having a surface roughness Ra. An unstructured main surface 321 and an adhesive layer 140 are disposed on the substantially unstructured main surface 321 of the planarization backfill layer 325, wherein the adhesive layer 140 bonds the structured film 351 to the main surface 191 of the waveguide 190 and has an average thickness ta. In some embodiments, for at least a first wavelength W1 in the range of 400 nm to 2500 nm or other ranges described elsewhere herein, the refractive index difference between the planarization backfill layer 315 and the structured layer 310 is at least 0.25. In some embodiments, Ra <ta<1 / 4W1。

[0039] In some implementations, the structured layer 110, 210, or 310 includes multiple sublayers. For example, the structured layer can be formed by etching an unstructured layer, as further described elsewhere herein, and the unstructured layer can include a stack of sublayers such that the resulting engineered structure has sublayers. Figure 6B This is a schematic cross-sectional view of an article 301' comprising a structured film 351' bonded to a waveguide 190 according to some embodiments. The structured film 351' includes structured layers 310a and 310b, the structured layers including a first sublayer 310a disposed on a second sublayer 310b.

[0040] In some embodiments, the plurality of engineered structures 129, 229, or 329 include structures having at least two different heights. For example, structures having at least two different heights can be formed by etching through a resist layer that has at least two different heights. For example, see reference... Figures 7A to 7C The mask layer 131 can be omitted, and the resist layers 125, 225 or 325 can be multi-level resist layers, so that the pattern transfer process can provide multi-level patterns in the previous unstructured layers 110', 210' or 310' respectively. Figure 6CThis is a schematic cross-sectional view of an article 301" comprising a structured film 351" bonded to waveguide 190 according to some embodiments. The structured film 351" includes a structured layer 310", which includes structures 329a and 329b with different heights. In some embodiments, the structured layer 310" includes multiple sublayers, and the taller structure 329a includes more sublayers than the shorter sublayer 329b. For example, the upper sublayer of structure 329b (rather than structure 329a) may have been removed by etching.

[0041] Figures 7A to 7C The processes for fabricating structured membranes 150, 250, and 350 are schematically illustrated, respectively. The input membrane (e.g., a membrane roll) includes: a polymer substrate 130; an etch barrier layer 137 disposed on the polymer substrate 130; an unstructured layer 110' (correspondingly 210', 310') disposed on the unstructured layer; and a mask layer 131 disposed on the unstructured layer. In step A (correspondingly A', A”), a resist layer 125 (correspondingly 225, 325) is applied onto mask layer 131. This resist layer can be formed by copying from a tool, as further described elsewhere herein. Mask layer 131 may optionally be omitted (e.g., when a relatively low aspect ratio structure is required or when a multi-level structured layer is required), in which case the resist layer can serve as an etching mask for etching into the unstructured layer. In step B (correspondingly B', B”), through-etching is performed, followed by etching of mask layer 131. Both etching steps can utilize, for example, reactive ion etching (RIE). In step C (correspondingly C', C”), etching continues until resist layers 125 (correspondingly 225, 325) have been removed. In step D (correspondingly D', D”), the etching conditions are changed (e.g., changed to oxygen RIE) to etch into the unstructured layers 110' (correspondingly 210', 310') until the vias reach the etch barrier layer 137. Figure 7CIn step D”, directional etching (e.g., directional RIE) is performed at an angle to create a tilted structure. Angle etching to create a tilted structure is described, for example, in U.S. Patent 10,670,862 (Vallius et al.) and U.S. Patent Application Publication 2016 / 0033784 (Levola et al.). In step E (correspondingly E', E”), etching continues until the mask layer 131 is removed. The structured layer 110 (correspondingly 210, 310), combined with the exposed portion of the mask layer, defines a main surface 111 (correspondingly 211, 311) facing away from the polymer substrate 130. In step F (correspondingly F', F”), the via is backfilled with a planarizing backfill (e.g., via atomic layer deposition). The planarizing backfill may have a main surface 116 (correspondingly 216, 316) facing the main surface 111 (correspondingly 211, 311) and substantially conforming to the main surface (e.g., deviating from conformity by no more than 20% or 10% of t2). The planarizing backfill may have a roughness Ra greater than desired. 0 Higher surface roughness, where grooves or valleys correspond to the through-holes below. In some embodiments, steps G (correspondingly G', G”) are performed to reduce the surface roughness to Ra. <Ra 0 In some implementations, Ra is less than 30 nm, or less than 20 nm, or less than 10 nm, or less than 5 nm, or less than 2 nm, or less than 1 nm, or less than 0.5 nm. In some such implementations, or in other implementations, Ra 0 -Ra is greater than 10 nm, or greater than 20 nm, or greater than 40 nm, or greater than 80 nm. In some embodiments, rough surfaces are smoothed by chemical mechanical planarization (e.g., using an abrasive with a corrosive chemical slurry), as generally described, for example, in U.S. Patents 6,623,355 (McClain et al.) and 9,200,180 (Banerjee et al.). In some embodiments, rough surfaces are smoothed by a combination of mechanical polishing and dry etching, as generally described, for example, in U.S. Patent 6,858,537 (Brewer). In step H (correspondingly H, H'), adhesive layer 140 is applied to planarization backfill layer 115 (correspondingly 215, 315). In some applications (e.g., for visible optics applications), surface roughness less than 5 nm, or less than 2 nm, or less than 1 nm, or less than 0.5 nm may be preferred. In some embodiments, a removable liner is applied to the adhesive layer 140 prior to pressing and / or storing the structured membrane.

[0042] Figures 7A to 7CThe etching step can be a plasma etching step. Ion-assisted plasma processing is conveniently used when high aspect ratio structures are required. Methods for achieving anisotropic etching include reactive ion etching (RIE), high-density ion source processing, or a combination of high-density ion source processing and RIE. High-density plasma can be generated via inductive radio frequency or microwave coupling or via a helical ion source. Linear high-density plasma sources are particularly advantageous for generating high aspect ratio features. Combining high-density plasma with RIE allows for the decoupling of ion generation (via high-density plasma) from ion energy (via RIE bias voltage).

[0043] RIE methods involve etching portions of a host surface that are not protected by a mask layer to form structures (e.g., nanostructures) on a substrate. In some embodiments, this method can be performed using a continuous roll-to-roll process known as “cylindrical reactive ion etching” (cylindrical RIE). Cylindrical RIE utilizes rotating cylindrical electrodes to provide anisotropic etched nanostructures on the surface of a substrate or article. Typically, a cylindrical RIE can be described as follows: A rotating cylindrical electrode (“cylindrical electrode”) powered by radio frequency coupling and a grounded counter electrode are provided inside a vacuum chamber. The counter electrode may include the vacuum chamber itself. An etching gas is supplied into the vacuum chamber and ignited and maintained between the cylinder electrode and the grounded counter electrode.

[0044] A continuous substrate, including a patterned mask layer, can then be wound around the circumference of the cylinder, and the substrate can be etched in a direction perpendicular to the substrate plane. The exposure time of the substrate can be controlled to obtain a predetermined etching depth of the resulting nanostructure. This process can be performed at an operating pressure of approximately 1 mTorr to 10 mTorr. Cylindrical RIEs are described, for example, in U.S. Patent 8,460,568 (David et al.).

[0045] When multiple materials are present, the chemical properties of the plasma environment can be controlled to achieve etching selectivity. Oxygen, as well as mixtures of oxygen and fluorinated gases, are used for example to etch carbon-containing materials such as polymers, diamond-like carbon, and diamond. The concentration of fluorine in the plasma can be selected to optimize the etching rate and selectivity. Typically, small amounts of fluorinated gas are used to significantly increase the etching rate of hydrocarbon polymers by up to 300%.

[0046] In order to etch silicon materials (silicon dioxide, SiO) xMaterials such as diamond-like carbon (DLC), silicon nitride, silicon carbide, silicon carbide, polysiloxane, silsesquioxane (SSQ) resins, etc., are used in combination with oxygen, employing mixtures of fluorocarbon compounds such as CF4, C2F6, and / or C3F8. The etching selectivity between silicon materials and hydrocarbon polymers can be carefully tailored by obtaining etching profiles of these materials as a function of the F / O atomic ratio in the plasma feed gas mixture. Oxygen-rich conditions provide excellent selectivity for etching hydrocarbon polymers and diamond-like carbon (DLC) while using silicon materials as a mask layer. In contrast, fluorine-rich conditions provide excellent selectivity for etching silicon materials while using hydrocarbon polymer-based mask materials.

[0047] Fluorinated plasma chemicals can be used to etch other mask materials whose fluorides are volatile, such as tungsten. Chlorine-containing gas mixtures can be used to etch materials whose chlorides are volatile, such as aluminum and titanium. The oxides, nitrides, and carbides of these etchable metals can also be etched using chlorine-based chemicals. Silicon nitride, aluminum nitride, and titanium oxide are high-refractive-index materials that can be etched using chlorine chemicals.

[0048] Considering the material type and layer thickness, various deposition methods can be used to deposit the individual layers (e.g., mask layer 131; etch barrier layer 137; layers 110', 210', 310'; backfill layers 115, 215, 315; or binder layer 140). Suitable deposition methods may include chemical vapor deposition (CVD), sputtering coating, physical vapor deposition (PVD), atomic layer deposition (ALD), or combinations thereof. Thin layers or films can be coated onto flat or structured surfaces using coating methods known in the art, such as slot die coating, slope coating, curtain coating, blade coating, swab coating, dip coating, and spin coating. Slot die coating equipment is described, for example, in U.S. Patents 5,639,305 (Brown et al.) and 7,591,903 (Maier et al.). Spin coaters are described, for example, in U.S. Patent 6,033,728 (Kikuchi et al.).

[0049] The planarization backfill layer (e.g., 115, 215, 315) can be formed of any suitable material. Preferably, for at least the first wavelength W1, the planarization backfill layer is formed of a material whose refractive index is at least 0.2, or at least 0.25, or at least 0.3, or at least 0.35 higher than that of the structured layer (e.g., 115, 215, 315). Suitable materials for the backfill layer include: acrylate resin filled with zirconium oxide or titanium dioxide, which can be deposited, for example, by coating; metal oxides, nitrides, and oxynitrides, including oxides, nitrides, and oxynitrides of, for example, Si, Ti, Zr, Hf, Nb, Ta, or Ce, which can be, for example, vapor-deposited; and parylene, which can be applied, for example, by coating. Since silicon is a metalloid, silicon oxide, silicon nitride, and silicon oxynitride are considered as metal oxides, metal nitrides, and metal oxynitrides, respectively. In some cases, titanium dioxide (TiO2) is preferably used for optical applications involving visible light, while silicon or other metal oxides can be used for applications involving near-infrared light. The structured layer can be formed from any of the low-refractive-index materials described elsewhere herein. The structured layer can be, for example, a fluoropolymer layer. In some embodiments, the structured layer comprises a fluoropolymer, and the planarization backfill layer comprises a metal oxide, nitride, or oxynitride. In some embodiments, the structured layer has a refractive index of no more than 1.4 for at least a first wavelength W1, and the planarization backfill layer has a refractive index of at least 1.65 or at least 1.7.

[0050] In some embodiments, the wavelength of interest is in the visible or near-infrared range. Therefore, the first wavelength W1 may be in the range of 400 nm to 2500 nm. In some embodiments, the visible wavelength is of primary interest. Therefore, the first wavelength W1 may be in the range of 400 nm to 700 nm. In some embodiments, the near-infrared wavelength is of primary interest. Therefore, the first wavelength W1 may be, for example, in the range of 700 nm to 2500 nm or 800 nm to 2000 nm. Some specific near-infrared wavelengths that may be of interest depending on the application include, for example, 850 nm, 905 nm, 940 nm, 1060 nm, 1330 nm, and 1550 nm.

[0051] In some embodiments, resist layer 125, 225, or 325 comprises a silicone-containing polymer. In some embodiments, the resist layer comprises a siloxane, silicone resin, or silsesquioxane. In some embodiments, the resist layer comprises a cross-linked acrylate. Suitable resist layers are described, for example, in U.S. Patent 5,811,183 (Shaw et al.). The resist layer may have a total thickness, for example, in the range of 50 nm to 500 nm.

[0052] The resist layer 125, 225, or 325 can be formed using various pattern printing, transfer, tiling, copying, or replication techniques, which may include a master mold manufactured via, for example, light, electron beam, grayscale, two-photon, or nanoimprint lithography methods, or microcontact printing (μCP) methods. Replication techniques (e.g., nanoreplication) may include, for example, casting and curing a structured surface with a tool. Suitable casting and curing methods, and suitable resins used with such methods, are described, for example, in U.S. Patent 5,175,030 (Lu et al.) and U.S. Patent 5,183,597 (Lu), and in U.S. Patent Application Publication 2012 / 0064296 (Walker, JR. et al.). Other available methods and / or materials for forming the resist layer are described, for example, in the following U.S. Patents: U.S. Patent 8,658,248 (Anderson et al.); 5,811,183 (Shaw et al.); and U.S. Patent 6,045,864 (Lyons et al.). Structured tools can be manufactured using any suitable manufacturing method, such as by photolithography or electron beam lithography to prepare tool masters, metal copies thereof, polymer copies of tool masters or their metal copies, polymer copies of such polymer copies, direct writing tools or any copies thereof, copies of structured pads or any copies thereof. Suitable manufacturing methods are described, for example, in the following applications: International Application Publication WO 2009 / 002637 (Zhang et al.), and U.S. Patent Application Publications 2007 / 0065636 (Merrill et al.) and 2014 / 0193612 (Yu et al.); and U.S. Patent 8,460,568 (David et al.). The tool can be manufactured, for example, by diamond turning. Exemplary diamond turning systems and methods are described, for example, in the following patents: U.S. Patent 7,350,442 (Ehnes et al.); U.S. Patent 7,328,638 (Gardiner et al.) and 6,322,236 (Campbell et al.). An example of patterned subwavelength gratings can be found in: Chun-Wei Liu, Jiwang Yan, Shih-Chieh Lin, “Diamond turning of high-precision roll-to-roll imprinting molds for fabricating subwavelength gratings”, Optical Engineering, Vol. 55, No. 6, 064105 (2016), doi: 10.1117 / 1.OE.55.6.064105..:10.1117 / 1.OE.55.6.064105.

[0053] Mask layer 131 may be made of any material that has suitable etch selectivity for layers 110', 210', or 310'. In some embodiments, mask layer 131 is or comprises a metal or a silicon-containing metal oxide. Examples include chromium (Cr), aluminum (Al), copper (Cu), titanium (Ti), tungsten (W), germanium (Ge), iridium (Ir), platinum (Pt), ruthenium (Ru), osmium (Os), rhenium (Re), alloys thereof, or silicon-containing oxides thereof. In some embodiments, mask layer 131 comprises SiO2, Si x O y N z (x=1, y=1~2, z=0~1) or Si x Al y O z (x = 1, y = 0–1, z = 1–2). Available oxides are described, for example, in U.S. Patent Application Publication 2015 / 0214405 (Nachtigal et al.). Available materials include, for example, titanium nitride (TiN), alumina (Al₂O₃), aluminum and chromium (Al / Cr) metal alloys, and Si. x C y H z (x=1, y=1~4, z=1~4) or Si x C y N z H n (x=1, y=1~4, z=0~1, n=1~4), Si x N y (x = 1, y = 0~1), SiO x (x=1~2), SiH x (x = 1 to 4). Other suitable materials include, for example, diamond-like glass as described in U.S. Patent 8,034,452 (Padiyath et al.). Mask layer 131 may also be referred to as a hard mask layer.

[0054] The etch barrier layer 137 may be made of any material that has suitable etch selectivity for layers 110', 210', or 310'. In some embodiments, the etch barrier layer 137 is or includes a metal (e.g., Cr, Al, Ti, Zr, Ta, Hf, Nb, Ce, or alloys thereof) or a metal oxide (e.g., an oxide of any of these metals, such as Al2O3 or Si). x Al y O z (For example, x = 1, y = 0~1, z = 1~2); or Si x O y N z(e.g., x = 1, y = 1–2, z = 0–1)), or metal nitrides (e.g., nitrides of any of these metals, or Si). x O y N z In some embodiments, for example, the etch barrier layer 137 is or includes indium tin oxide, tin oxide, or aluminum oxide (Al₂O₃). Available materials include, for example, Si. x C y H z (For example, x = 1, y = 1~4, z = 1~4), Si x C y N z H n (For example, x = 1, y = 1~4, z = 0~1, n = 1~4), Si x N y (For example, x = 1, y = 0~1), SiO x (For example, x = 1 to 2), Si x O y N z (For example, x = 1, y = 1~2, z = 0~1), or SiH x (e.g., x = 1 to 4). Other suitable materials include, for example, diamond-like glass. In some embodiments, the etch barrier layer 137 is optically transparent, which can be understood to mean that for a wavelength range of 400 nm to 700 nm, the etch barrier layer has an average optical transmittance of at least 60% for substantially perpendicular incident light.

[0055] For example, the average thickness of the mask layer 131 and / or the etch barrier layer 137 may be in the range of about 1 nm to about 200 nm, or about 2 nm to about 50 nm, or about 2.5 nm to about 10 nm. The mask layer 131 may have an average thickness of, for example, less than 50 nm, or less than 25 nm, and / or greater than 5 nm. The etch barrier layer 137 may have an average thickness of, for example, less than 25 nm and / or greater than 2 nm.

[0056] The etch barrier layer 137 can be selected from materials having a desired optical transmittance at the wavelength of interest to obtain a suitable thickness. In some embodiments, for at least the first wavelength W1, the etch barrier layer 137 has an optical transmittance of at least 60% or at least 70% for substantially perpendicular incident light. In some embodiments, the structured layer is formed of one or more unstructured layers (e.g., any one of layers 110′, 210′, 310′ may be a single layer comprising multiple sublayers). In some embodiments, for at least the first wavelength W1, one or more unstructured layers have an optical transmittance of at least 60% or at least 70% for substantially perpendicular incident light.

[0057] Figure 8 This is a schematic cross-sectional view showing one or more unstructured layers 777, incident light 773, and transmitted light 774. The incident light 773 is incident substantially perpendicularly (e.g., within 20 degrees, 10 degrees, or 5 degrees of the normal) onto one or more unstructured layers 777. These unstructured layers can be a single layer (e.g., corresponding to any of layers 131, 137, 110', 210', 310', or an unstructured layer formed of the material of any of layers 115, 215, or 315 with a thickness of t1+t2) or can be a stack (e.g., corresponding to layers 131, 137 and 110', 210', or 310'). The incident light 773 is schematically represented as having a wavelength λ in the range λ1 to λ2. The range of λ1 to λ2 can be, for example, 400 nm to 2500 nm, or 400 nm to 700 nm, or 700 nm to 2500 nm. The wavelength λ can be a single wavelength (e.g., a first wavelength W1) or a wavelength range (e.g., 400 nm to 700 nm). In some embodiments, for at least the first wavelength W1, one or more unstructured layers 777 may have an optical transmittance of at least 60%, at least 70%, or at least 80% for substantially perpendicularly incident light. In some embodiments, for example, for a wavelength range of 400 nm to 2500 nm or 400 nm to 700 nm, one or more unstructured layers 777 may have an average optical transmittance (an unweighted average of optical transmittance within a given wavelength range) of at least 50%, at least 60%, at least 70%, or at least 80% for substantially perpendicularly incident light.

[0058] In some implementations, a wafer master (e.g., a semiconductor wafer substrate with nanopatterns etched into the wafer surface, typically silicon or silicon dioxide on silicon) is used to fabricate a structured film, which can be used, for example, to apply nanostructures to a waveguide. The wafer master can be generated, for example, using standard master fabrication techniques such as electron beam lithography or immersion lithography. The master pattern can then be replicated into a series of process intermediates, which may include a polymer copy (imprint resist on the wafer), a polymer mold (imprint resist on a polymer), a tiled polymer matrix (a tiled wafer pattern on a large glass substrate), electroformed nickel pads, and a soldered nickel sleeve. The soldered nickel sleeve can be used in a continuous casting and curing (e.g., nanoreplication) process to, for example, produce a structured film. The wafer pattern can be used in a single-element layout, or it can be composited with other patterns from other wafers to form a composite layout. Each wafer pattern can be performed as a single element throughout the process and then combined during the lamination step, or, for example, all wafer patterns except one can be composited in a tiling polymer matrix step and formed into a single composite roll. For example, the remaining elements can then be laminated onto opposite sides of the waveguide plate without being combined with other elements.

[0059] In some embodiments, a composite method is used, in which individual nanopatterns are composited within an intermediate (such as a tiled polymer matrix) for fabricating composite gaskets, sleeves, and membranes. The gaskets on the structured membrane can be laser-kissed to expose the adhesive in the structured regions of the membrane (e.g., optical coupler regions), and the entire membrane can be laminated to a waveguide. This approach is useful, for example, if all couplers are on the same side of the waveguide. In some embodiments, a single-element method is used, in which individual nanopatterns are carried as single elements from a wafer to the membrane. In this case, the number of membranes can be the same as the number of wafers. Elements from each membrane can be prepared as described elsewhere herein and composited during lamination. In some embodiments, a combination of composite and single-element methods is used, in which some, but not all, of the individual nanopatterns are applied on one side of the waveguide in the composite method, and the remaining individual nanopatterns are applied on the opposite side of the waveguide in the single-element method.

[0060] For example, the laminated waveguide plate can be laser-cut around the adhered coupler region, and waste can be removed. In some embodiments, the resulting laminate represents a finished optical article. In other embodiments, the laminate is processed in a further discretization step to produce the final optical article. For example, in some embodiments, the waveguide can be segmented into multiple near-eye (NTE) augmented reality (AR) waveguides.

[0061] Example

[0062] Structured film products were fabricated using nanofiber replication, solvent coating, plasma etching, vacuum thin film deposition, and lamination methods. The resulting structures are optical products with a nanostructured optical functional layer (titanium dioxide) bonded to a acceptor substrate (such as a polished glass sheet).

[0063] These examples are for illustrative purposes only and are not intended to be limiting. Unless otherwise specified, all parts, percentages, ratios, etc., in the examples and the remainder of the specification are by weight. Unless otherwise specified, the solvents and other reagents used were obtained from Sigma-Aldrich Chemical Company, St. Louis, Missouri.

[0064] Material

[0065]

[0066]

[0067]

[0068] Preparation Example

[0069] Preparation Example 1 (PE1)

[0070] An acrylate solution was prepared by first adding 75 wt% PHOTOMER 6210, 25 wt% SR238, and 0.5 wt% TPO to form a first acrylate mixture. A second acrylate mixture was obtained by manually mixing 93 wt% of the first acrylate mixture with 7 wt% HFPO-UA. An acrylate solution was then produced by manually mixing 14 wt% of the second acrylate mixture with 43 wt% PGME and 43 wt% MEK.

[0071] Preparation Example 2 (PE2)

[0072] An adhesive enhancer solution was prepared by adding 0.3 wt% of compound 01 with 99.7 wt% MEK and 0.003 wt% TPO-L.

[0073] Preparation Example 3 (Resin D)

[0074] An acrylate resin mixture was prepared by combining and mixing PHOTOMER 6210, SR238, SR351 and TPO in a weight ratio of 60 / 20 / 20 / 0.5.

[0075] Preparation Example 4 (Substrate 01)

[0076] A releasable layer is coated on an ST505 film using a roll-to-roll vacuum coating machine similar to the coating machine described in U.S. Patent Application 20100316852 (Condo et al.), by adding a second evaporator and curing system between the plasma pretreatment station and the first sputtering system, and using an evaporator as described in U.S. Patent 8,658,248 (Anderson and Ramos) to manufacture a substrate with a releasable layer.

[0077] ST505 films were prepared for coating by nitrogen plasma treatment to improve the adhesion of the metal layer. The nitrogen plasma treatment of the film was carried out at 120 W using a titanium cathode, with a roll speed of 9.8 m / min and the back side of the film kept in contact with a coating roller cooled to 0°C.

[0078] On the prepared ST505 substrate, a 90% / 10% Si / Al release layer was deposited in accordance with the previous plasma treatment steps. A conventional AC sputtering process using Ar gas and operating at 16 kW power was used to deposit a 7 nm thick SiAl alloy layer onto the substrate. The SiAl-coated PET substrate was then rewound.

[0079] An acrylate transfer layer, SR833, containing less than 1 wt% of Compound 1, was applied to the release layer via ultrasonic atomization and flash evaporation. The flow rate of the liquid monomer entering the evaporator was 0.67 mL / min. The nitrogen flow rate was 100 standard cubic centimeters / min (SCCM), and the evaporator temperature was set to 500℉ (260°C). The temperature of the processing barrel was 14℉ (-10°C). The monomer coating was then immediately cured downstream using an electron beam curing gun operating at 7.0 kV and 10.0 mA to produce an acrylate thickness of 180 nm.

[0080] Preparation Example 5 (FPI)

[0081] Pentafluorobenzoylmethoxyphenylphosphine oxide was synthesized in a flame-dried, three-necked round-bottom flask equipped with a thermocouple, magnetic stir bar, and liquid feeding funnel, under yellow ambient light and vacuum. The round-bottom flask was refilled with dry nitrogen, and 9.92 g (58.3 mmol) of dimethoxyphenylphosphine was added.

[0082] 13.44 g (58.3 mmol) of pentafluorobenzoyl chloride was added to a liquid feeding funnel, and the reaction apparatus was connected to a vacuum. The round-bottom flask was cooled with a dry ice / isopropanol bath, and pentafluorobenzoyl chloride was added dropwise at a rate sufficient to keep the reaction temperature below 15 °C. During this process, the reaction mixture turned into a bright yellow-orange pourable viscous oil. The quantitative yield of pentafluorobenzoylmethoxyphenylphosphine oxide was collected and stored in a brown glass wide-mouth bottle.

[0083] Preparation Example 6 (HFPO-FCA)

[0084] Under nitrogen atmosphere, 120 g (0.0663 mol, 1810 MW) of HFPO oligomer diacrylate (Mn = 2000 g / mol, prepared according to the synthetic method substantially described in U.S. Patent 9,718,961 (Corveleyn et al.)) and 120 g of 1,1,1-trifluorotoluene, previously dried as a 50% solid solution on a 4 Å molecular sieve in a diaphragm-sealed flask, were added to a 500 mL round-bottom flask equipped with a stir bar and a diaphragm. Next, 1.42 g (1.46 mL, 0.007366 mol, 193.32 number-average MW) of N-methyl-3-aminopropyltrimethoxysilane was added, and the reaction was stirred at room temperature (RT) for 2 h, during which time the aliquots were evaluated by 1H Fourier transform nuclear magnetic resonance spectroscopy (FT-NMR) of D8-tetrahydrofuran / CFC 113. The reaction was then concentrated in a rotary evaporator at 57°C and 2 Torr for about 30 minutes, and bottled under nitrogen.

[0085] Hypothetical Example 1

[0086] Optical products are manufactured using the following processes:

[0087] Step 1. Nanoscale replication of the template layer

[0088] A nanostructured mold film was prepared by coating a resin D-mold onto a polycarbonate film. The coated film was then pressed onto a nanostructured nickel surface, which was attached to a steel roller controlled at a speed of 15.2 m / min using a rubber-coated roller at 60°C. The nanostructured nickel surface consisted of twelve patterned regions of 6 mm × 6 mm, with feature sizes ranging from 75 nm to 500 nm. The patterned regions were composed of multi-spacing patterns with spacings of 150 nm, 200 nm, and 250 nm, and feature widths half the spacing (75 nm, 100 nm, 125 nm).

[0089] The features are arranged in a square grid, with the spacing varying along two axes, resulting in nine repeating rectangular units with all combinations of the aforementioned widths. Within this repeating unit, the 150nm spacing portion has 27 features, the 200nm spacing portion has 20 features, and the 250nm spacing portion has 16 features. The features are approximately 200nm high and have sidewall angles of approximately 4 degrees.

[0090] The resin D coating on the membrane is thick enough to completely wet the nickel surface and forms rolling beads of resin when the coated membrane is pressed onto the nanostructured nickel surface. The membrane is exposed to radiation from two Fusion UV lamp systems (trade name "F600" from Fusion UV Systems, Gaithersburg, mD), both operating at 142 W / cm, simultaneously in contact with the nanostructured nickel surface. After the membrane is peeled off from the nanostructured nickel surface, the nanostructured side of the membrane is exposed to radiation from the Fusion UV lamp systems again.

[0091] Step 2: Demolding

[0092] In a parallel-plate capacitively coupled plasma reactor, a silicon-containing anti-stick film layer assembled according to the methods described in U.S. Patents 6,696,157 (David et al.) and 8,664,323 (Iyer et al.) and U.S. Patent Application Publication 2013 / 0229378 (Iyer et al.) is applied to a nanostructured mold membrane. The chamber has a surface area of ​​1.7 m². 2 (18.3ft 2 The central cylindrical current-carrying electrode.

[0093] After placing the nanostructured mold onto the energized electrodes, the reaction chamber was pumped down to a base pressure of less than 1.3 Pa (2 mTorr). O2 gas was then introduced into the chamber at a rate of 1000 SCCM. Processing was performed using plasma-enhanced CVD by coupling radio frequency (RF) power into the reactor at a frequency of 13.56 MHz and an applied power of 2000 W. The processing time was controlled by moving the nanostructured mold membrane through the reaction zone at a rate of 9.1 m / min (30 ft / min), resulting in an exposure time of approximately 10 seconds. After deposition was complete, the RF power was turned off, and the gas was evacuated from the reactor.

[0094] Following the first treatment, a second plasma treatment was performed in the same reactor without returning the chamber to atmospheric pressure. HMDSO gas was introduced into the chamber at approximately 1750 SCCM to achieve a pressure of 9 mTorr. Subsequently, 13.56 MHz RF power was coupled into the reactor at an applied power of 1000 W. The membrane was then transported through the reaction zone at a rate of 9.1 m / min (30 ft / min) for an exposure time of approximately 10 seconds. At the end of this treatment time, the RF power and gas supply were stopped, the chamber was returned to atmospheric pressure, and the demolded nanostructured molded membrane was removed from the chamber.

[0095] Step 3: Pattern Transfer Film

[0096] Pattern transfer films were prepared by depositing an etch barrier layer and a pattern transfer layer onto an 11.5-inch wide ST505 PET substrate film via reactive sputtering and organic vapor deposition in systems similar to those described in U.S. Patents 5,440,446 (Shaw et al.) and 7,018,713 (Padiyath et al.). The substrate film was coated in a roll-to-roll (R2R) format. On the first pass through the system, the substrate film was treated with nitrogen plasma from an unbalanced DC magnetron cathode with a titanium target at a nitrogen flow rate of 50 W and 100 SCCM.

[0097] Immediately after plasma treatment of the film, approximately 12 nm of SiAlO was sputtered onto the plasma-treated surface. x A base etch barrier layer was applied. A pair of rotating cathodes were controlled using a 40 kHz AC power supply; each cathode was fitted with a 90% / 10% Si / Al sputtering target (obtained from Soleras Advanced Coatings ETS, Biddeford, ME). During sputtering deposition, a voltage signal from the power supply was used as input to a proportional-integral-derivative (PID) control loop to maintain a predetermined oxygen flow rate at each cathode. Sputtering conditions were: 16 kW AC power, a linear velocity of 9.75 m / min (32 ft / min), a gas mixture containing 350 SCCM argon and 223 SCCM oxygen, and a sputtering pressure of 2.6 mTorr.

[0098] Then, using the organic vapor deposition system and method described in U.S. Patent 8,658,248 (Anderson et al.), SiAlO was vapor-coated with a layer of approximately 100 nm thick 90% HFPO-FCA / 9% HFPO / 1% FPI (wt%). x Surface. Maintain a linear velocity of 3.81 m / min (12.5 ft / min) while keeping the back side of the film in contact with the coating barrel cooled to 0°C. Prior to coating, the monomer was degassed to 20 mTorr under vacuum. The liquid was pumped into an ultrasonic nebulizer at a flow rate of 1.0 ml / min using a syringe pump, with a nitrogen flow rate of 10 SCCM introduced into the nebulizer. The liquid was flash-evaporated at 250°C and delivered to SiAlO. x Surface. The vapor stream condenses onto the film surface and is cured by UV radiation using a low-pressure mercury arc lamp.

[0099] Using the same method described for etching the barrier layer on the substrate, approximately 12 nm thick SiAlO x The top etch barrier layer is deposited on the HFPO-FCA / HFPO / FPI surface.

[0100] Step 4: Adhesion enhancer

[0101] The PE2 adhesion promoter solution was applied to the pattern transfer film produced in step 3 using a slit-die coating process. The solution was pumped at 3 SCCM through the slit-die onto the film, which was moving at a rate of 6 m / min. The film was then passed through a 65°C oven for 1.5 minutes, cured using a Fusion H lamp, and subsequently rolled up.

[0102] Step 5: Resist Transfer

[0103] The nanostructured mold film obtained from step 2, after being treated with a release agent, was applied using a slit-type die with an acrylic ester solution PE1 at a rate of 3 m / min. The solution was applied to a width of 10.16 cm and pumped using a Harvard syringe pump at a rate of 1.05 SCCM. The coating was partially cured for 1.5 meters from solution application using a 405 nm UV-LED system powered at 0.2 amps at 40 volts. The coating underwent approximately 0.005 W / cm² in the UV-Vis spectrum. 2 Irradiance.

[0104] Then, the film is dried under ambient conditions for 3 minutes before entering the roll gap. At the roll gap, the pattern transfer film obtained in step 4 (with a base etch barrier layer, a transfer layer, a top etch barrier layer, and an adhesion promoter) is laminated with a PE1-coated, release-treated template film.

[0105] The roller gap consists of a rubber roller with a hardness of 90 and a steel roller set at 37°C. The roller gap is engaged by two Bimba cylinders with a pressure of 0.28 MPa.

[0106] The coated PE1 acrylate solution was cured using a Fusion H lamp, and the first acrylate mixture was separated from the molded template film, leaving a cured PE1 coating on the transfer film over the entire 6mm × 6mm patterned area. The web tension was set to approximately 0.0057 N / m.

[0107] Step 6: Etch the transfer layer

[0108] The etched patterned transfer film is prepared by etching the patterned transfer film obtained in step 5 according to the reactive ion etching method.

[0109] In step 2, reactive ion etching is performed on the patterned film in the same reaction chamber used for depositing the anti-sticking treatment layer. After the patterned transfer film is placed on the energized electrode, the reaction chamber is pumped down to a base pressure of less than 1.3 Pa (1 mTorr). A mixture of PF-5060 and oxygen is introduced into the chamber at rates of 100 SCCM and 50 SCCM, respectively. A 13.56 MHz RF power is then coupled into the reactor with an applied power of 7500 W. The film is then transported through the reaction zone at a rate of 1.2 m / min (4 ft / min) to achieve an exposure time of approximately 75 seconds for transferring the pattern to the top etch barrier layer.

[0110] Upon completion of the first etching step, the RF power is switched off and the gas is vented from the reactor. Following the first etching, a second reactive ion etching process is performed in the same reactor without returning the chamber to atmospheric pressure. Oxygen is introduced into the chamber at a flow rate of 275 SCCM. Subsequently, 13.56 MHz RF power is coupled into the reactor at an applied power of 7500 W.

[0111] The patterned transfer membrane is then transported through the reaction zone at a rate of 7.6 m / min (25 ft / min) to obtain an exposure time of approximately 12 seconds. At the end of this treatment time, RF power and gas supply are stopped, and the chamber is returned to atmospheric pressure.

[0112] Additional information on materials and processes for continuous reactive ion etching via nanostructured masks, as well as further details about the reactor, can be found in U.S. Patent 8,460,568 (David et al.).

[0113] Step 7: TiO2 backfilling

[0114] A backfilled nanostructured film was formed by depositing TiO2 into the etched patterned transfer film obtained in step 6. The TiO2 backfill layer was formed from a tetrakis(isopropoxy)titanium (TTIP) precursor using a space atomic layer deposition (ALD) process. Planar coating was performed in a space R2R ALD machine, as described in PCT Patent Publication 2017 / 172531 (Lyons et al.). TiO2 was deposited in an environment of 1.1 Torr N2 and 0.3 Torr CO2 using TTIP heated to 80°C and 300 SCCM N2 push gas, along with plasma discharge (approximately 0.50 mA / cm2). The ALD chamber was heated to 100°C.

[0115] The membrane was translated through the ALD chamber multiple times at a speed of 30.48 m / min (100 ft / min), with one precursor exposure and one plasma exposure per ALD cycle, and each chamber was traversed 72 ALD cycles. The membrane was translated through the ALD chamber 10 to 50 times to produce a TiO2 layer of sufficient thickness to fill the etched nanostructures in the transfer membrane and form a flat surface on top of the nanostructured regions of the transfer membrane.

[0116] Step 8: Applying the adhesive layer solution

[0117] An adhesive layer was formed on the surface of the TiO2-backfilled nanostructured membrane obtained in step 7 by applying an adhesive coating solution to a slit die in a roll-to-roll process. The adhesive coating solution was prepared by diluting a certain amount of FG1901G in sufficient cyclohexane to produce a solution containing 0.33% by weight of total solids. The solution was coated onto the membrane from step 5 at a controlled speed and flow rate to produce a wet coating thickness of approximately 9 micrometers. The coated web traveled approximately 2.4 m (8 ft) and then entered a 9.1 m (30 ft) conventional air flotation dryer, all three zones of which were set at 80°C (176°F). After drying, the adhesive coating thickness was approximately 30 nanometers.

[0118] Step 9: Lamination onto the glass substrate

[0119] Optical articles are formed by laminating the binder-coated nanostructured film obtained in step 8 onto a glass substrate. A suitable glass substrate is a 1.1 mm thick, 76.2 mm diameter Eagle XG glass wafer with a surface roughness of less than 1 nm RMS. The binder-coated structured film is placed sideways on one surface of the glass wafer and laminated onto the glass substrate using an HL-100 hot-roll laminator (ChemInstruments, West Chester Township, OH) set to 80 psi, 40 cm / min, and 115 °C.

[0120] Hypothetical Example 2

[0121] Complete steps 1-7 as in hypothetical embodiment 1.

[0122] Step 7a: Thinning TiO2 and backfilling

[0123] Reactive ion etching was performed on the TiO2-backfilled nanostructured film constructed in step 7 to reduce the thickness of the planarized ALD TiO2 layer. In step 2 of hypothetical example 1, reactive ion etching was performed on the film in the same reaction chamber used for depositing the release treatment layer. After the patterned transfer film was placed on the energized electrode, the reaction chamber was pumped down to a base pressure of less than 1.3 Pa (1 mTorr). Nitrogen trifluoride gas was introduced into the chamber at a rate of 1000 SCCM. Subsequently, 13.56 MHz RF power was coupled into the reactor with an applied power of 7500 W. The film was then conveyed through the reaction zone to achieve a planar removal rate at an exposure time of 100 nm / min. The exposure time was selected to leave a thin planar TiO2 layer on the nanostructured film, such that the residual layer was less than 50 nm thick.

[0124] Repeat steps 8 and 9 as in hypothetical embodiment 1.

[0125] Hypothetical Example 3

[0126] The optical article is prepared as described in Hypothetical Example 1 or Hypothetical Example 2, except that in step 1, the nanostructured mold film is prepared on substrate O1 instead of polycarbonate.

[0127] Following step 9, the 90% / 10% Si / Al layer of substrate 01 is weakened by exposing the ST505 film to UV light. After UV exposure, the substrate is removed by structurally peeling off the ST505 substrate, leaving the structure attached to the glass wafer.

[0128] Terms such as “about” will be understood in the context in which they are used and described by those skilled in the art. If it is unclear to those skilled in the art in the context of their use and description of “about” to express quantities of characteristic size, quantity, and physical properties, then “about” will be understood to mean within 10% of a specified value. A quantity given a specified value as “about” can be precisely the specified value. For example, if it is unclear to those skilled in the art in the context of their use and description of this specification, a quantity having a value of about 1 means that the quantity has a value between 0.9 and 1.1, and that the value can be 1.

[0129] All cited references, patents, and patent applications are incorporated herein by reference in their entirety in a consistent manner. In the event of any inconsistency or contradiction between the incorporated references and this application, the information in the foregoing description shall prevail.

[0130] Unless otherwise stated, the description of elements in the accompanying drawings should be understood to apply equally to corresponding elements in the other drawings. While specific embodiments have been illustrated and described herein, those skilled in the art will recognize that various alternative and / or equivalent embodiments may be used instead of the illustrated and described embodiments without departing from the scope of this disclosure. This application is intended to cover any modifications, variations, or combinations of the specific embodiments discussed herein. Therefore, this disclosure is intended to be limited only by the claims and their equivalents.

Claims

1. An optical article, the optical article comprising: waveguide; and Structured membrane, the structured membrane comprising: Polymer substrate; An etching barrier layer is disposed on the polymer substrate; A structured layer comprising a plurality of engineered structures disposed on the side of the etch barrier layer opposite to the polymer substrate; A planarization backfill layer disposed above the plurality of engineered structures to define a substantially flat main surface having a surface roughness Ra less than 5 nm, wherein the refractive index difference between the planarization backfill layer and the structured layer is at least 0.25 for at least a first wavelength W1 in the range of 400 nm to 700 nm; and An adhesive layer is disposed on the substantially flat main surface of the planarized backfill layer and bonds the structured film to the waveguide. The adhesive layer has an average thickness ta and Ra. <ta<1 / 4W1。 2. The optical article of claim 1, wherein the structured film further comprises an unstructured layer disposed between the etch barrier layer and the polymer substrate, wherein the refractive index difference between the planarization backfill layer and the unstructured layer is at least 0.2 for at least the first wavelength W1.

3. The optical article of claim 1, wherein the engineered structure is tilted relative to the etch barrier layer.

4. The optical article according to any one of claims 1 to 3, wherein the optical article further comprises a dynamic separation layer disposed between the etch barrier layer and the polymer substrate.

5. The optical article according to any one of claims 1 to 3, wherein the average thickness ta is less than 250 nm.

6. The optical article according to any one of claims 1 to 3, wherein the average thickness ta is less than 100 nm.

7. The optical article according to any one of claims 1 to 3, wherein the plurality of engineered structures comprises a plurality of nanostructures.

8. A structured membrane, the structured membrane comprising: Polymer substrate; An etching barrier layer is disposed on the polymer substrate; A structured layer comprising a plurality of engineered structures disposed on the side of the etch barrier layer opposite to the polymer substrate, the engineered structures being inclined relative to the etch barrier layer; A planarization backfill layer disposed above the plurality of engineered structures to define a substantially flat main surface of the planarization backfill layer having a surface roughness Ra of less than 5 nm, wherein the refractive index difference between the planarization backfill layer and the structured layer is at least 0.25 for at least a first wavelength W1 in the range of 400 nm to 700 nm. and An adhesive layer having an average thickness ta and disposed on the substantially flat main surface of the leveled backfill layer, Ra <ta<1 / 4W1。 9. The structured membrane of claim 8, wherein at least a majority of each engineered structure of the engineered structure includes a sidewall defined at an external angle between the sidewall and the etch barrier layer in the range of 45 to 85 degrees.

10. The structured membrane of claim 8, wherein the structured layer comprises a fluoropolymer, and the planarization backfill layer comprises a metal oxide, a nitride, or a nitrogen oxide.

11. An optical article, the optical article comprising: waveguide; as well as A structured film is disposed on the main surface of the waveguide, and the structured film includes: Etching barrier layer; A structured layer disposed on the etch barrier layer and comprising a plurality of engineered structures, the engineered structures being inclined relative to the etch barrier layer; A planarization backfill layer disposed above the plurality of engineered structures to define a substantially unstructured primary surface of the planarization backfill layer having a surface roughness Ra less than 5 nm, wherein the refractive index difference between the planarization backfill layer and the structured layer is at least 0.25 for at least a first wavelength W1 in the range of 400 nm to 700 nm; and An adhesive layer is disposed on the substantially unstructured main surface of the planarized backfill layer, the adhesive layer bonding the structured film to the main surface of the waveguide and having an average thickness ta, Ra. <ta<1 / 4W1。 12. A structured membrane, the structured membrane comprising: Polymer substrate; Etching barrier layer; A dynamic separation layer is disposed between the polymer substrate and the etch barrier layer; A structured layer comprising a plurality of engineered structures disposed on the side of the etch barrier layer opposite to the dynamic separation layer; A planarization backfill layer disposed above the plurality of engineered structures to define a substantially flat main surface of the planarization backfill layer having a surface roughness Ra of less than 5 nm, wherein the refractive index difference between the planarization backfill layer and the structured layer is at least 0.25 for at least a first wavelength W1 in the range of 400 nm to 700 nm. and An adhesive layer having an average thickness ta and disposed on the substantially flat main surface of the leveled backfill layer, Ra <ta<1 / 4W1, The dynamic separation layer is adapted to facilitate the separation of the polymer substrate and the etch barrier layer upon activation.

13. The structured membrane of claim 12, wherein the dynamic separation layer is adapted to be released from the etch barrier layer upon activation.

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