Method for treating a substrate surface, apparatus therefor, and processed glass article

Abstract

Apparatus and methods for processing a substrate, e.g., texturing a substrate. In some embodiments, a masking material is applied to a surface of the substrate in a predetermined pattern, and the surface is subsequently contacted with an etchant that removes the masking material. Contacting the surface with the etchant produces a plurality of juxtaposed textures. In other embodiments, the masking step can be omitted, and the etchant is applied in a predetermined pattern to produce a plurality of juxtaposed textures. In yet other embodiments, the substrate has a chemical composition, and the substrate is exposed to an exudate that leaches at least one component of the chemical composition to produce a substrate with a chemical composition that varies across the substrate.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims the benefit of priority under "35 U.S.C.§119" to U.S. Provisional Patent Application No. 62 / 962,529, filed on January 17, 2020, the content of which is relied upon and incorporated herein by reference in its entirety.

[0002] The disclosure of the present invention relates to a method of processing a substrate surface including a method of forming a substrate surface having an anisotropic surface texture, an apparatus for forming an anisotropic surface texture, and an article comprising an anisotropic surface texture.

Background Art

[0003] Texturing the surface of a substrate, such as a glass substrate, is known for a wide range of applications such as light scattering and / or light trapping (e.g., in the solar panel industry), improving bioactivity in medical technology, reducing the unique tribocharging phenomenon in the flat panel display industry, and sonar detection. Methods of texturing can include wet etching using an etchant, dry etching using, for example, plasma discharge, and laser ablation. Lasers can be used to physically ablate the substrate to induce small defects in the form of cracks and / or depressions or to locally modify the substrate structure through heating and / or phase change. Various forms of wet or dry chemical etching are widely utilized across many different industries to controllably machine the substrate surface and generate random or periodic features as needed. However, such methods are typically homogeneous in that they are applied uniformly across the entire surface of the substrate and produce isotropic surface characteristics (e.g., roughness). The glass thermal history during formation or the post - relaxation thermal cycle can potentially modify the textured surface at the micro or macro scale. Texturing the substrate surface is not difficult in view of the amount of available methods, but intentionally patterning multiple types of features on the substrate surface using a single - step process has not been clearly elucidated.

Summary of the Invention

Problems to be Solved by the Invention

[0004] A substrate surface showing one or more anisotropic textures may enable multiple functionalities for the same product. From the perspective of manufacturability, such products can provide even more attractive technological paths without adding expensive capital engineering upgrades.

Means for Solving the Problems

[0005] Disclosed by the present disclosure is a substrate having a first main surface with a periodic first texture, for example, a glass substrate. The first texture has a first size and a first spatial period in a first direction along a first axis. The first texture extends along the first axis for a length equal to or greater than twice the first spatial period. The first size can be, for example, in the range of about 2 nanometers to about 500 nanometers. The first spatial period can be in the range of about 0.1 millimeter to about 100 millimeters.

[0006] The first main surface can further include an isotropic second texture juxtaposed with the first texture. The second texture has an average surface roughness Sa equal to or less than about 1 nanometer.

[0007] The first main surface can further include a periodic third texture juxtaposed with the first texture, for example, juxtaposed with the first texture and the second texture. The third texture has a second size and a second spatial period along a second axis different from the first axis. The second texture extends along the second axis for a length equal to or greater than twice the second spatial period.

[0008] The second axis can be orthogonal to the first axis. The second size can be in the range of about 2 nm to about 500 nm. The second spatial period can be in the range of about 0.1 mm to about 25 mm.

[0009] In another embodiment, a substrate is described that includes a first major surface having a periodic first texture with a first size and a first spatial period along a first direction along the first axis, for example, a glass substrate. The first texture extends along the first axis for a length equal to or greater than twice the first spatial period, and an isotropic second texture is juxtaposed with the first texture. The first size can be in the range of about 2 nanometers to about 500 nanometers. The first spatial period can be in the range of about 0.1 millimeter to about 100 millimeters. The average surface roughness Sa of the second texture can be equal to or less than about 1 nanometer.

[0010] The glass substrate can further include a periodic third texture juxtaposed with the first texture, for example, juxtaposed with the first texture and the second texture. The third texture has a second size and a second spatial period along a second axis different from the first axis. The second texture extends along the second axis for a length equal to or greater than twice the second spatial period. The second axis can be orthogonal to the first axis. The second size can be in the range of about 2 nm to about 500 nm. The second spatial period can be in the range of about 0.1 mm to about 25 mm.

[0011] The substrate can further comprise a periodic fourth texture juxtaposed with the first texture, for example, juxtaposed with the first texture, the second texture, and the third texture. The fourth texture has a third size and a third spatial period along a second axis, and the fourth texture extends along the second axis with a length equal to or greater than twice the third spatial period. The third size can be in the range of about 2 nanometers to about 500 nanometers. The third spatial period can be in the range of about 0.1 millimeter to about 25 millimeters.

[0012] In yet another embodiment, a method of texturing a substrate, such as a glass substrate, is disclosed that includes transporting the substrate along a transport path in a transport direction and applying a masking material in a first predetermined pattern to a first major surface of the substrate as the substrate is transported. An etchant is applied over a first region of the first major surface after the step of applying the masking material as the substrate is transported. The etchant etches the first major surface, removes the masking material, and forms a first texture having a first size and a first spatial period along a first axis in the first region. The etching can form, for example, a second texture juxtaposed with the first texture on the first major surface, and the second texture has an average surface roughness Sa less than about 1 nanometer. The first texture can be isotropic. The second texture can be isotropic. The first size can be in the range of about 2 nm to about 100 nm. The first spatial period can be in the range of about 0.1 millimeter to about 100 millimeters.

[0013] The etching can further form a third texture juxtaposed with the first texture, for example, juxtaposed with the first texture and the second texture. The third texture has a second size and a second spatial period along a second axis different from the first axis. The third texture can be anisotropic.

[0014] Etching can further form, for example, a fourth texture juxtaposed with the first texture, the fourth texture juxtaposed with the first texture, the second texture, and the third texture, and the fourth texture has a third size and a third spatial period along the second axis. The second axis can be orthogonal to the first axis.

[0015] In some embodiments, the first pattern can comprise parallel and spaced-apart rows of alternating peaks and valleys.

[0016] In some embodiments, the masking material can be uncured while the etching solution is added. The masking material can comprise a polymer such as polyurethane, polyolefin, acrylate, novolak, or silicone. In some embodiments, the masking material can comprise styrene maleic acid.

[0017] In various embodiments, the removal rate of the masking material by the etching solution can be lower than the dissolution rate of the substrate surface. For example, in some embodiments, the masking material can be completely removed from the first major surface during etching.

[0018] The step of adding the masking material can comprise the step of adding the masking material using a roller having a plurality of ridges. The plurality of ridges can be concentric with, for example, the shaft of the roller. The plurality of ridges can be formed by a plurality of wheels arranged along a rotational axis orthogonal to the conveyance direction.

[0019] In some embodiments, the plurality of ridges can be parallel to the shaft of the roller.

[0020] In various embodiments, the step of adding the masking material can comprise the step of adding the masking material using a plurality of roller assemblies.

[0021] In various embodiments, the etchant can comprise HF, H3PO4, or a combination thereof.

[0022] In yet other embodiments, a method of texturing a substrate, such as a glass substrate, is disclosed that includes transporting the substrate along a transport path in a transport direction and applying an etchant in a predetermined pattern onto a first major surface of the substrate as the substrate is transported. The etchant etches the first major surface and forms a first texture having a first size and a first spatial period along a first axis.

[0023] The etching can further form a second texture juxtaposed with the first texture on the first major surface, the second texture having a surface roughness Sa less than about 1 nanometer. The first texture can be anisotropic. The second texture can be isotropic. The first size can be in the range of about 2 nanometers to about 100 nanometers. The first period can be in the range of about 0.1 millimeter to about 100 millimeters.

[0024] In some embodiments, the etching can form a third texture juxtaposed with the first texture, e.g., juxtaposed with the first and second textures, the third texture having a second size and a second spatial period along a second axis different from the first axis. The third texture can be anisotropic.

[0025] In some embodiments, the etching can form a fourth texture juxtaposed with the first texture, e.g., juxtaposed with the first, second, and third textures, the fourth texture having a third size and a third spatial period along the second axis. The second axis can be orthogonal to the first axis.

[0026] In various embodiments, the first pattern can comprise parallel and spaced-apart rows of alternating peaks and valleys.

[0027] In some embodiments, the step of adding the etchant can include contacting a roller having a plurality of ridges with the first major surface. The plurality of ridges can be formed, for example, by a plurality of wheels aligned along a rotation axis orthogonal to the transport direction.

[0028] The step of adding the etchant may include contacting the first major surface with a plurality of roller assemblies.

[0029] The etchant can comprise HF, H3PO4, or a combination thereof.

[0030] In another embodiment, a substrate having a first surface with a first chemical composition, such as a glass substrate, is described, wherein the concentration of at least one component of the first chemical composition varies periodically along a first axis with a first spatial period.

[0031] The concentration of at least one component can vary periodically along a second axis different from the first axis with a second spatial period. The angle between the first axis and the second axis can be greater than 0 degrees and equal to or less than 90 degrees.

[0032] In yet another embodiment, a method of making a substrate, such as a glass substrate, having an anisotropic surface chemistry is disclosed, the method comprising transporting a glass sheet along a transport path in a transport direction, adding a masking material in a first predetermined pattern to a first region of a first major surface of the substrate when the substrate is transported, the adding step wherein the first major surface has a first chemical composition, and adding an exudate to the first major surface when the substrate is transported, the adding step wherein the exudate leaches at least one component of the first chemical composition from the first major surface and removes the masking material, and the concentration of at least one component of the first chemical composition varies periodically along a first axis with a first spatial period after leaching.

[0033] The first spatial period can be in the range of from about 0.1 mm to about 100 mm.

[0034] In some embodiments, the concentration of at least one component along a second axis different from the first axis can vary periodically with a second spatial period. The concentration along the second axis is anisotropic. The second axis can be orthogonal to the first axis.

[0035] In some embodiments, the masking material can be uncured while the exudate is being added.

[0036] The masking material can comprise a polymer such as polyurethane, polyolefin, acrylate, novolak, or silicone. In some embodiments, the masking material can comprise styrene maleic acid. In various embodiments, the masking material can be completely removed from the first major surface during etching.

[0037] In some embodiments, the step of adding the masking material can comprise contacting the first major surface with a roller having a plurality of ridges. The plurality of ridges can be formed by a plurality of wheels aligned along a rotational axis orthogonal to the transport direction. The step of adding the masking material can comprise adding the masking material using a plurality of roller assemblies.

[0038] The exudate can comprise at least one of, for example, HCl, H2SO4, H3PO4, or HNO3.

[0039] The at least one component can comprise at least one of Mg, Ca, Sr, Al, or B.

[0040] In still other embodiments, a method for texturing a substrate, e.g., a glass substrate, is described that includes transporting a substrate along a transport path in a transport direction, applying a masking material to a main surface of the substrate as the substrate is transported, and applying an exudate over the main surface in a first predetermined pattern as the substrate is transported, where the main surface has a first chemical composition and the exudate leaches at least one component of the first chemical composition from the first main surface such that the concentration of at least one component of the first chemical composition varies periodically along a first axis with a first spatial period after leaching. The first texture can be anisotropic. The first size can be in the range of about 2 nm to about 500 nm.

[0041] Additional features and advantages of the embodiments disclosed herein are set forth in the following detailed description and will be partly apparent to those skilled in the art from that description, or may be recognized by practicing the embodiments described herein, which include the following detailed description, the claims, and the accompanying drawings.

[0042] It is to be understood that both the foregoing general description and the following detailed description present embodiments intended to provide an overview or framework for understanding the nature and characteristics of the embodiments disclosed herein. The accompanying drawings, which are incorporated herein and constitute a part hereof, are included to provide a further understanding and illustrate various embodiments of the disclosure of the invention and explain the principles and operations thereof together with the description.

Brief Description of the Drawings

[0043]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 3C

Figure 4A

Figure 4B

Figure 4C

Figure 5

Figure 6

Figure 7A

Figure 7B

Figure 7C

Figure 8A

Figure 8B

Figure 9

Figure 10A

Figure 10B

Figure 10C

Figure 10D

Figure 11

Figure 12A

Figure 12B

Figure 12C

Figure 12D

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

[0044] Reference is now made in detail to embodiments of the disclosure of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like parts. However, the disclosure of the invention can be embodied in many different forms and should not be construed as limited to the embodiments described herein.

[0045] As used herein, the term "about" reflects that the quantity, size, formulation, parameter, and other quantities and characteristics are not exact, need not be exact, reflect factors such as tolerances, conversion factors, rounding, and measurement errors, and other factors known to those skilled in the art, and is approximate and / or may be larger or smaller as desired.

[0046] In this specification, a range can be expressed as from "about" one value and / or to "about" another value. When expressing such a range, in another embodiment, it includes from one value to the other value. Similarly, when using the term "about" to express a value as an approximation, it will be understood that that value forms another embodiment. Further, it will be understood that the endpoints of each range are significant both in relation to and independent of the other endpoints.

[0047] As used herein, directional terms such as above, below, right, left, front, rear, top, bottom are provided only in relation to the figures when drawn and are not intended to imply an absolute orientation.

[0048] Unless otherwise expressly stated, none of the methods described in this specification are to be construed as requiring that the steps be performed in a particular order, nor are any of the devices herein ever intended to require a particular orientation. Accordingly, when the claims of a method do not actually recite the order that the steps are to follow, or when the claims of any device do not actually recite an order or orientation with respect to individual components, or when the claims or the specification do not otherwise clearly indicate in another way that the steps are to be limited to a particular order, or when a particular order or orientation with respect to the components of a device is not recited, it is never intended that an order or orientation be inferred. This applies to any non-expressive basis that might be considered in relation to logical issues regarding the arrangement of steps, the flow of operations, the order of components, or the orientation of components, the plain meaning derived from grammar construction or punctuation, and all conceivable non-expressive bases for an interpretation that includes the number or type of embodiments described in the specification.

[0049] As used herein, a noun that is not in the plural includes reference to the plural unless the context clearly indicates otherwise. Thus, for example, reference to a component that is not in the plural includes embodiments having two or more such components unless the context clearly indicates otherwise.

[0050] As used herein, the words "exemplary," "example," or various forms thereof are used to indicate an example, instance, or illustration. No aspect or design described herein as "exemplary" or "an example" should be construed as preferred or advantageous over other aspects or designs. Further, examples are provided merely for clarity and understanding and are not intended to limit or restrict the disclosed subject matter or the relevant portions of the disclosure of the present invention in any way. Although numerous additional examples or alternative examples within various ranges are possible, it is to be understood that they are omitted for the sake of brevity.

[0051] As used herein, the terms "comprising," "including," and variations thereof shall be construed as synonymous and non-limiting unless otherwise indicated. A list of elements following a transitional phrase comprising or including is a non-exclusive list such that there may be additional elements other than those specifically listed within the list.

[0052] As used herein, the terms "substantially," "substantially," and variations thereof are intended to represent that the feature being described is equal to or approximately equal to a value or description. For example, a "substantially planar" surface is intended to indicate a surface that is planar or approximately planar. Further, "substantially" is intended to indicate that two values are equal to or approximately equal to each other. In some embodiments, "substantially" can mean values within about 10% of each other, such as within about 5% of each other, or within about 2% of each other.

[0053] As used herein, an anisotropic surface texture is a surface texture that includes attributes different from a second direction different from a first direction in which the main surface of a substrate moves in the first direction of movement of the main surface of the substrate, but the difference does not substantially change. For example, for a first line profile obtained across the main surface of the substrate in a first orientation and a second line profile obtained across the main surface in a different orientation, for example, an orientation orthogonal to the first line profile, it is possible to determine the difference between the average roughness Ra1 of the first line profile and the average roughness Ra2 of the second line profile. However, regardless of the location on the main surface where the first line profile and the second line profile are obtained, if the absolute orientation of the first line profile and the second line profile and the relative orientation of the first line profile with respect to the second line profile remain the same, the difference in the selection characteristics between the first line profile and the second line profile is the same. That is, the magnitude of the average roughness of the first line profile remains the same regardless of the position on the main surface, and the magnitude of the average roughness of the second line profile remains the same regardless of the position on the main surface. Therefore, the average roughness of the first line profile obtained at any location on the main surface with respect to a first predetermined length (the predetermined length can be greater than two cycle lengths (i.e., repetitions) of the maximum surface characteristics with respect to the main surface) and a first orientation on the main surface is substantially equal within the measurement function range to the average roughness of another line profile obtained at any other location on the main surface with respect to the first predetermined length and the first orientation with respect to the main surface. Similarly, the average roughness of the second line profile obtained at any location on the main surface with respect to a second predetermined length (the predetermined length can be greater than two cycle lengths (i.e., repetitions) of the maximum surface characteristics with respect to the main surface) having a second orientation different from the first orientation is substantially equal to the average roughness of another line profile obtained at any other location on the main surface with respect to the second predetermined length and the second orientation, and the difference between any average roughness related to the first line profile and any average roughness related to the second line profile is substantially constant.

[0054] Shown in FIGS. 1 and 2 are respectively a cross-sectional side view and a top view of an exemplary processing apparatus 10 for processing a main surface of a substrate 12. As used herein, the term "substrate" includes sheets, plates, ribbons, or pans of material. The substrate can be a laminated substrate having multiple layers of the same or different materials. The substrate 12 can comprise a glass-based material. As used herein, "glass-based" includes both glass and glass-ceramics, and glass-ceramics have one or more crystalline phases and an amorphous residual glass phase. A glass-based material (e.g., a glass-based substrate) can comprise an amorphous material (e.g., glass) and optionally one or more crystalline materials (e.g., ceramics). Exemplary glasses can include aluminosilicate glass, borosilicate glass, soda-lime glass, etc. In some embodiments, the substrate 12 can comprise a silicon wafer or a silicon sheet. In another embodiment, the substrate 12 can comprise lithium fluoride (LiF), magnesium fluoride (MgF2), calcium fluoride (CaF2), barium fluoride (BaF2), sapphire (Al2O3), zinc selenide (ZnSe), germanium (Ge), or other materials. The substrate 12 can be used for various display applications such as liquid crystal displays (LCDs), electrophoretic displays (EPDs), organic light-emitting diode displays (OLEDs), or plasma display panels (PDPs).

[0055] The substrate 12 includes a first main surface 14 and a second main surface 16 facing the first main surface 14. In some embodiments, the first main surface 14 can be parallel to the second main surface 16, while in other embodiments, the first main surface 14 may not be parallel to the second main surface 16. For example, in some embodiments, the cross-sectional shape of the substrate 12 obtained through the thickness of the substrate in the length direction or the width direction orthogonal to the length direction can be wedge-shaped. In this case, one of the first or second main surfaces is angled with respect to the other of the first or second main surfaces at an angle greater than, for example, 0 degrees (parallel) but less than about 10 degrees. The substrate 12 can have a thickness "T" in the range of about 50 micrometers (μm) to about 0.7 mm, for example, in the range of about 50 μm to about 0.5 mm, defined between the first main surface 14 and the second main surface 16. In this case, the thickness T is measured perpendicular to one or both of the main surfaces. In another embodiment, other thicknesses and / or non-flexible configurations can be provided. For example, in another embodiment, the substrate 12 can have a thickness in the range of about 50 μm to about 3 mm, for example, in the range of about 0.5 mm to about 3 mm.

[0056] The substrate 12 has a quadrilateral peripheral shape in the plane of the first or second main surface, and can include a leading edge 18 associated with the conveyance direction 20 of the substrate 12, a trailing edge 22 opposite to the leading edge 18, and opposing side edges 24, 26. The conveyance direction 20 can be the length direction of the substrate. In various embodiments, the leading edge 18 and the trailing edge 22 can be parallel edges. In an embodiment, the side edges 24 and 26 can be parallel edges. In some embodiments, the leading edge 18 can be perpendicular to one or both of the side edges 24 or 26. For example, in some embodiments, the substrate 12 can have a rectangular shape in the plane of one or both of the first or second main surfaces 14 or 16. In that case, the side edges 24, 26 are parallel to the conveyance direction 20, and the leading and trailing edges 18, 22 are perpendicular to the conveyance direction 20.

[0057] As shown in FIGS. 1 and 2, the processing apparatus 10 can include a plurality of transport rollers 28 configured to transport the substrate 12 in the transport direction 20 along the transport path 30, a masking roller 32, a first container 34 forming a masking material reservoir 35, an etching solution roller 36, and a second container 38 forming an etching solution reservoir 39. The processing apparatus 10 can further include an etching solution circulation system 40 configured to be in fluid communication with the reservoir 39 and circulate the etching solution into the second container 38 through a pump 42 and a pipe 44.

[0058] The conveying roller 28 can be a full-length roller rotatably mounted and configured to rotate around the rotation axis 64. In this case, the length 88 of the conveying roller in the direction orthogonal to the conveying direction 20 can be equal to or greater than the width 90 of the substrate 12 defined between the first and second side edges 24, 26 (see FIG. 2A). The conveying roller 28 can be a driven roller. For example, the conveying roller 28 can be coupled to one or more motors (not shown) that rotate the conveying roller 28 around their respective rotation axes to convey the substrate 12 in the conveying direction 20 along the conveying path 30. In another embodiment, the conveying roller 28 is non-driven so that it can freely rotate around its respective rotation axis. In yet another embodiment, the processing device 10 can include a combination of driven and non-driven conveying rollers 28. The conveying roller 28 is shown positioned below the substrate 12 and thereby supporting the substrate 12 on the first main surface 14. However, in another embodiment, additional conveying rollers 28 can be positioned above the substrate 12 and can contact the second main surface 16. For example, the upper conveying roller that contacts the second main surface 16 can be a driven roller that propels the substrate 12 in the conveying direction 20 over the non-driven lower conveying roller. In some embodiments, one or more pairs of conveying rollers can be configured to extend partially in a direction orthogonal to the conveying direction 20. For example, in some embodiments, a conveying roller such as an upper conveying roller (not shown) that contacts the second main surface 16 can contact the edge portion of the substrate 12 and not contact the central portion of the first and / or second main surfaces.

[0059] Referring further to FIGS. 1 and 2, the masking roller 32 can be positioned along the transport path 30 in a manner similar to the transport roller 28. Thus, the masking roller 32 can extend across the width 90 of the substrate 12 in a direction orthogonal to the transport direction 20, in which case the length 92 of the masking roller 32 can be equal to or greater than the width 90 of the substrate 12. However, the length 92 of the masking roller 32 can be made smaller than the width 90 of the substrate 12 if less than the entire area of the substrate is to be processed. As shown in FIG. 3A, the masking roller 32 can include a shaft 46 having a longitudinal axis (e.g., a rotational axis) 48 and a roller body 50 including a plurality of ridges 52 separated by grooves 54. That is, the ridges 52 and the grooves 54 can alternate in the length direction of the masking roller parallel to the longitudinal axis 48. The longitudinal axis 48, which is the rotational axis, can be arranged to be orthogonal to the transport direction 20. In some embodiments, the masking roller 32 can be of a single-piece construction such that the roller body 50 is, for example, originally formed or by securely joining a plurality of parts as shown in FIG. 3A. Thus, in some embodiments, the roller body 50 can be connected to the shaft 46, in which case the shaft 46 and the roller body 50 can rotate together about the rotational axis 48. In another embodiment, as shown in FIG. 3B, the masking roller 32 can include a plurality of wheels 56 spaced apart by projections (not shown) on the wheel 56 or by spacers 58 alternately arranged between the wheels 56 and positioned on the shaft 46, in which case the diameter of the spacers in the direction orthogonal to the rotational axis 48 is smaller than the diameter of the wheels. In such an embodiment, the wheels 56 form the ridges 52 and the spacers 58 form the grooves 54. In some embodiments, the wheels 56 can be rotatable independently of the shaft 46 about the rotational axis 48, in which case the wheels 56 can rotate independently of another wheel 56.In such an embodiment, the shaft 46 can remain stationary while the wheel and optionally the spacer rotate, but in another embodiment, the shaft 46 and the wheel 56 can be individually freely rotatable about the axis of rotation 48.

[0060] In some embodiments, the masking roller 32 can be a driven roller coupled to a motor (not shown) that rotates the masking roller, e.g., the shaft 46, about the axis of rotation 48, and in another embodiment, the masking roller 32 can be undriven and freely rotatable. In some embodiments, the masking roller 32 can be coupled to the transport roller 28. For example, the processing apparatus 10 can include a drive mechanism configured to rotate the transport roller 28 and the masking roller 32 simultaneously. That is, in some embodiments, the rotation of the masking roller 32 can be synchronized with the rotation of the transport roller 28, so that the masking roller 32 rotates at the same rotational speed as the transport roller 28 and can assist in the movement of the substrate 12 in the transport direction 20. For example, in some embodiments, the transport roller 28 and the masking roller 32 can be driven by a chain through gears coupled to their respective shafts, and the chain is coupled to a motor that drives the chain and thereby rotates the transport roller 28 and the masking roller 32, and in another embodiment, the transport roller 28 and / or the masking roller 32 can be driven entirely by gears. In yet another embodiment, the transport roller 28 and / or the masking roller 32 can be rotated by one or more belts coupled to a motor. Other transport methods known in the art of the present invention can be used in addition to or in place of this. In some embodiments, the processing apparatus 10 can include a single masking roller 32, but in another embodiment, the processing apparatus 10 can include a plurality of masking rollers 32.

[0061] The roller body 50 (or wheel 56) can comprise a plurality of layers, such as concentric layers. In some embodiments, the roller body 50 can comprise an outer layer formed of polyvinyl chloride (PVC), although other materials that are easy to machine, are wettable when contacting an etching-resistant polymer, and impart rigidity can also be used.

[0062] The masking roller 32 is shown in FIGS. 3A and 3B as comprising a plurality of ridges formed by a straight circular cylinder section having a peripheral surface 84 defined between opposing circular edges, although the ridges 52 can have other peripheral surface shapes. For example, the ridges 52 can have a peripheral surface with a wavy edge, a peripheral surface with parallel edges (i.e., the same diameter is defined between the peripheries of two circles located in parallel planes, and the centers of each are on the same line orthogonal to the parallel planes), a peripheral surface with a zigzag or serrated edge, or an edge design composed of other regular or irregular curves. The opposing edges of such surface shapes need not be symmetric. FIG. 3C shows four exemplary peripheral surface edge patterns defined between the side edges 60, 62 of the ridge: (a) a circular edge, (b) a wavy edge, (c) a square wave edge, and (d) a zigzag (serrated) edge. Other peripheral surface patterns are possible and are contemplated.

[0063] The masking roller 32 is rotatable about the axis of rotation 48, and at least the peripheral surface 84 of the ridges 52 can be mounted over the first container 34 through the shaft 46 such that it contacts, e.g., is immersed in, the masking material 66 confined in the first container 34. The masking material 66 can comprise any suitable masking material that is easily added as a liquid and removed by a selected etchant. For example, in some embodiments, the masking material 66 can comprise styrene maleic acid (SMA), although in other embodiments, other masking materials, such as acrylates, novolaks (phenol-formaldehyde resins with a formaldehyde to phenol molar ratio of less than 1), or silicones can be used.

[0064] The processing device 10 can further include a corrosion liquid roller 36 positioned along the transport path 30. In some embodiments, the processing device 10 can include a single corrosion liquid roller 36, while in other embodiments, the processing device 10 can include a plurality of corrosion liquid rollers 36. The corrosion liquid roller 36 can be rotatably mounted and can be rotatable about a rotation axis 64. The corrosion liquid roller 36 is positioned downstream of the masking roller 32 with respect to the transport direction 20, in which case the substrate 12 moving along the transport path 30 in the transport direction 20 encounters the corrosion liquid roller 36 after encountering the masking roller 32.

[0065] In some embodiments shown in FIGS. 4A and 4B, the corrosion liquid roller 36 can include a monolithic roller body 70 of a continuous (e.g., homogeneous) composition mounted on a shaft 72. However, in other embodiments, the roller body 70 can be non-homogeneous. In some embodiments, the roller body 70 can include a plurality of layers such as concentric layers. For example, as shown in FIG. 4C, the roller body 70 can include a core 74 coupled to the shaft 72 and an outer layer 76 positioned on the core 74 and defining an outer surface 86 of the corrosion liquid roller 36 coupled to the core 74. The corrosion liquid roller 36 can further include one or more intermediate layers between the core 74 and the outer layer 76. The core 74 can include a solid core, while in other embodiments, a hollow or partially hollow inner core can be provided. The core 74 can facilitate the transmission of torque from a motor coupled to the shaft 72 to rotate the corrosion liquid roller 36 about the rotation axis 64 to the outer layer 76, while the outer layer 76 can be fabricated from a material designed to provide a desirable lift of the corrosion liquid 78 from the second container 38 and a coating of the corrosion liquid on the first major surface 14 of the substrate 12 when the substrate 12 moves over the corrosion liquid roller 36. For example, the corrosion liquid roller 36 can include an outer layer 76 comprising a foam material. The outer layer 76 can include, for example, an open porous fibrous network of a corrosion liquid resistant material such as a polyurethane or polyolefin material.

[0066] Similar to the masking roller 32, the etchant roller 36 can extend across all or a part of the width 90 of the substrate 12 in a direction perpendicular to the conveying direction 20. That is, the rotation axis 64 of the etchant roller 36 can be perpendicular to the conveying direction 20. In an embodiment, the etchant roller 36 can be rotatably mounted on top of the second container 38 such that the peripheral surface 86 of the etchant roller 36 contacts, for example, is immersed in the etchant 78 confined in the second container 38. In various embodiments, the etchant 78 can comprise hydrofluoric acid (HF), but in other embodiments, other suitable etchants can be used depending on the material of the substrate 12. In the examples described herein, the etchant 78 comprises H3PO4 at a concentration of 1 mole (M) and NaF at a concentration of 0.35 mole at 40 °C. However, other suitable etchants can be used depending on the substrate material. For example, HF-based etching of glass is initially time-dependent, and the achievable average roughness Ra value ultimately saturates at about 0.5 nm. The resulting surface texture of the processed substrate 12 can be on the nanometer scale both in the lateral direction along with the height, and the correlation length can also be on the order of nanometers.

[0067] FIGS. 5 and 6 show another exemplary processing apparatus 100 comprising a plurality of conveying rollers 128 configured to convey the substrate 12 along the conveying path 130 in the conveying direction 120, an etchant roller 136, and a container 138 forming an etchant reservoir 139. The processing apparatus 100 can further comprise an etchant circulation system 140 configured to circulate the etchant into the container 138 through the pump 142 and the piping 144 in fluid communication with the etchant reservoir 139.

[0068] The conveying roller 128 can be a full-length roller. In this case, the length 94 of the conveying roller in the direction orthogonal to the conveying direction 120 can be equal to or greater than the width 90 of the substrate 12 defined between the first and second side edges 24, 26 (see FIG. 6). The conveying roller 128 can be a driven roller. For example, the conveying roller 128 can be coupled to a motor (not shown) that rotates the conveying roller 128 around its respective rotation axis to convey the substrate 12 in the conveying direction 120 along the conveying path 130. In other embodiments, the conveying roller 128 is not driven and can rotate freely individually. In still other embodiments, the processing apparatus 100 can include a combination of driven and non-driven conveying rollers 128. The conveying roller 128 is shown positioned below the substrate 12 and thereby supporting the substrate 12 on the first main surface 14. However, in yet another embodiment, additional conveying rollers 128 can be positioned above the substrate 12 and can contact the second main surface 16. For example, the upper conveying roller that contacts the second main surface 16 can be a driven roller that propels the substrate 12 in the conveying direction 120. In some embodiments, one or more pairs of conveying rollers can be configured to extend partially in a direction orthogonal to the conveying direction 20. For example, in some embodiments, the conveying roller can contact the edge portion of the second main surface 16 but not the central portion of the second main surface.

[0069] In some embodiments, the processing apparatus 100 can further include one corrosion liquid roller 136 configured to rotate around the rotation axis 132. However, in another embodiment, the processing apparatus 100 can include a plurality of corrosion liquid rollers 136. The corrosion liquid roller 136 can extend across the width 90 of the substrate 12 in a direction orthogonal to the transport direction 120. In this case, the length 96 of the corrosion liquid roller 136 can be equal to or greater than the width 90 of the substrate 12. However, in yet another embodiment, when it is intended to process less than the full width of the substrate 12, the length 96 can be smaller than the width 90. As shown in FIGS. 7A and 7B, the corrosion liquid roller 136 can include a shaft 172 and a roller body 170 including a plurality of ridges 152 separated by grooves 154. That is, the ridges 152 and the grooves 154 alternate in the longitudinal direction of the corrosion liquid roller 136 along the rotation axis 132.

[0070] In FIGS. 7A and 7B, the corrosion liquid roller 136 is shown as including a plurality of ridges formed by a straight circular cylinder section including a peripheral surface 156 defined between opposing circular edges. However, the ridges 152 can have other peripheral surface shapes. For example, the ridges 152 can include a peripheral surface having a wavy edge, a peripheral surface having parallel edges (i.e., the same diameter is defined between the peripheries of two circles located in parallel planes, and the centers of each are on the same line orthogonal to the parallel planes), a peripheral surface having a zigzag or serrated edge, or a peripheral surface composed of any other curve. The opposing edges of such surface shapes need not be symmetric. FIG. 7C shows four exemplary peripheral surface patterns defined between the side edges 160, 162 of the ridge: (a) a circular edge, (b) a wavy edge, (c) a square wave edge, and (d) a zigzag (serrated) edge. Other peripheral surface patterns are possible and are contemplated.

[0071] In some embodiments, as shown in FIG. 8A, the etchant roller 136 can comprise a monolithic roller body 170 of a continuous (e.g., homogeneous) composition mounted on a shaft 172. However, in yet another embodiment, the etchant roller body 170 can comprise a plurality of layers, such as concentric layers, as shown in FIG. 8B. Accordingly, the etchant roller body 170 can comprise a core 174 coupled to the shaft 172 and an outer layer 176 positioned on the core 174 and defining the perimeter of the etchant roller 136. Although not shown, the etchant roller 136 can further comprise one or more intermediate layers between the core 174 and the outer layer 176. The core 174 can comprise a solid core, but in other embodiments, a hollow or partially hollow inner core can be provided. The core 174 can facilitate the transmission of torque from a motor coupled to the shaft 172 for rotating the etchant roller 136 to the outer layer 176, while the outer layer 176 can be fabricated from a material designed to provide a desired lift of the etchant 178 from the container 138 and a coating of the etchant on the first major surface 14 of the substrate 12 as the substrate 12 moves over the etchant roller 36. For example, the etchant roller 136 can comprise an outer layer 176 comprising a foamed material. The outer layer 176 can comprise, for example, an open porous fibrous network of an etchant-resistant material such as a polyurethane or polyolefin material.

[0072] In some embodiments, the etchant roller 136 can be a driven roller. In this case, the etchant roller can be coupled to a motor (not shown) that rotates the etchant roller around the rotation axis 1328. On the other hand, in yet another embodiment, the etchant roller 136 is not driven and can be freely rotatable around the rotation axis 132. In some embodiments, the etchant roller 136 can be coupled to the transport roller 128. For example, the processing apparatus 100 can include a drive mechanism configured to rotate the transport roller 128 and the etchant roller 136 simultaneously. That is, in some embodiments, the rotation of the etchant roller 136 around the rotation axis 132 can be synchronized with the rotation of the transport roller 128, so that the etchant roller 136 rotates at the same rotation speed as the transport roller 128. For example, in some embodiments, the transport roller 128 and the etchant roller 136 can be driven by a chain, and the chain is coupled to a motor that drives the chain and thereby rotates the transport roller 128 and the etchant roller 136.

[0073] In some embodiments, the ridges 152 can be arranged at equal intervals along the etchant roller 136. For example, the interval pattern can be determined by the desired performance attributes of the processed substrate 12. Thus, in some embodiments, the ridges may not be arranged at equal intervals, or the individual ridges of the plurality of ridges can have different peripheral surface widths in a direction perpendicular to the transport direction.

[0074] The etchant roller 136 can be rotatably mounted on top of the container 138 through the shaft 172 such that at least the peripheral surface 156 of the ridge 152 contacts, for example, is immersed in, the etchant 78 confined in the container 138.

[0075] Unlike the processing device 10, the embodiment of the processing device 100 does not require a masking roller, and the functional benefits provided by the masking roller 32 in the processing device 10 are fulfilled by the etching solution roller 136 in the processing device 100. That is, instead of using a masking material to prevent direct erosion of the substrate surface by the etching solution 78, the etching solution is applied to the first main surface 14 of the substrate in a predetermined pattern by the patterned etching solution roller 136. The etching of the substrate main surface occurs most easily in the surface portion where the etching solution is directly applied by the etching solution roller 136, and then, due to the spreading of the etching solution on the substrate surface, the etching solution erodes the portion of the substrate surface where the etching solution is not directly applied by the etching solution roller. As a result, the portion of the substrate main surface to which the etching solution is directly applied by the etching solution roller 136 is etched more than those surface portions etched due to the spreading of the etching solution.

[0076] According to the method of the disclosure of the present invention, the substrate 12 can be conveyed, for example, by the conveying roller 28 adjacent to the etching solution roller 36, for example, above it. In an embodiment of the processing device 10, the first main surface 14 of the substrate 12 is spaced above and faces the free surface of the masking material 66. The method can further comprise the step of rotating the masking roller 32 around the rotation axis 48 to transfer the masking material 66 from the first container 34 to the first main surface 14 of the substrate 12 when the substrate 12 is conveyed in the conveying direction 20 along the conveying path 30. For example, the masking roller 32 can lift the masking material 66 from the first container 34 and bring it into contact with the first main surface 14 of the substrate 12, thereby rotating in a direction suitable for facilitating the translation of the substrate 12 in the conveying direction 20 while covering the first main surface 14 with a layer of the masking material 66.

[0077] When the masking roller 32 rotates, as the substrate 12 is conveyed in the conveying direction 20 along the conveying path 30, the masking material 66 is applied to the first major surface 14 of the substrate 12 in a predetermined pattern defined by the ridge 52. For example, in an embodiment where the ridge surface is defined between two parallel circular edges (see, for example, FIG. 3C(a)), the masking roller 32 is configured to deposit parallel rows of the masking material 66 on the first major surface 14 such that the first major surface 14 includes alternating parallel rows of the masking material 66, for example, rows covered with the masking material 66 and intervening uncovered rows 68 (see FIG. 9).

[0078] With the substrate 12 being conveyed forward in the conveying direction 20 along the conveying path 30, at this point, the first major surface 14 covered with the predetermined pattern by the masking material 66 passes over the etching liquid roller 36. When the etching liquid roller 36 rotates, the etching liquid 78 is applied to the first major surface 14 of the substrate 12, for example, over the rows of the masking material 66 and the uncovered rows 68 not covered with the masking material 66, for example, over the entire first major surface 14.

[0079] Referring now to FIGS. 10A through 10D, a series of cross-sectional profiles of the substrate 12 are provided as viewed in a cross-section of width 90, showing the removal of substrate material from the first major surface 14 in columns 68 not coated with masking material and the removal of columns of masking material 66. As this series shows, the removal of material across the uncoated portions of the substrate 12 begins rapidly after coating with the etchant 78, whereas the portions of the substrate coated with the masking material 66 are originally protected by the masking material. In FIG. 10A, columns of masking material 66 have already been added to the first major surface 14. In FIGS. 10B through 10C, the masking material is removed by the etchant 78, which is then able to erode an increasingly large surface area of the first major surface 14. However, due to the presence of the masking material, the removal of material in the area beneath the masking material 66 is delayed, such that at the locations where the masking material 66 has deposited on the first major surface 14, less substrate material is removed than in areas that were originally uncoated, e.g., columns (faces) 68 not coated with masking material. Finally, as shown in FIG. 10D, the masking material 66 can be completely removed from the first major surface 14, and the etchant 78 begins to erode and remove material from areas of the first major surface 14 that were previously coated with the masking material 66. In some cases, the removal of the masking material 66 can be rapid, taking only a few seconds. In any event, a substrate is obtained having a surface that includes a plurality of ridge regions 80 and a plurality of recessed or valley regions 82 that alternate across the first major surface 14. That is, after etching with the etchant 78, the first major surface 14 can have low-frequency undulations related to peaks and valleys representing thickness variations of the substrate, where in this case the thickness of the valley regions is less than the thickness of the peak regions. As used herein, the term "thickness" nominally refers to the distance between the major surfaces of the substrate 12 in a direction orthogonal to at least one of the first or second major surfaces (e.g., prior to etching). In addition to this, both the ridge regions and the recessed regions can further have a fine and substantially isotropic texture resulting from the overall etching action of the etchant covering the first major surface 14.Accordingly, the first major surface 14 after etching according to the disclosure of the present invention can comprise a first low-frequency macroscale anisotropic texture resulting from a combination of masked and unmasked regions of the etched substrate surface. The substrate can further comprise a fine high-frequency isotropic surface texture imposed on both the original masked and unmasked regions, where the anisotropic texture includes peak-to-peak period and size, while the isotropic texture is best characterized by an average surface roughness Sa equal to or less than about 1 nanometer, this texture extending across the surface of the substrate to which the etchant has been applied and being uniform regardless of the direction across the surface.

[0080] In another embodiment, a similar method can be used for the embodiment of the processing apparatus 100. However, as described above with reference to the embodiment of the processing apparatus 10, instead of the etchant 78 being uniformly applied across the surface of the substrate and the masking material delaying direct etching of the surface in a predetermined area of the surface, according to the embodiment of the processing apparatus 100, the etchant 78 can be selectively applied to the first major surface 14 of the substrate 12, whereby a specific area of the substrate to which the etchant 78 is directly applied is etched more rapidly than other areas of the substrate to which the etchant is not directly applied. That is, the rows of the etchant-coated portions of the first major surface 14 are separated by the rows 98 of the uncoated surface portions (see FIG. 11). As shown in FIG. 12A, the etchant 78 is applied in parallel rows to the first major surface 14 and begins removing material from the first major surface 14 of the substrate 12. In FIG. 12B, the etchant begins to spread and the removal of material extends beyond the original etchant application area. FIG. 12C shows the increasingly greater removal of material, illustrating that more material is removed in the area where the etchant was originally applied than in the area where the etchant later spread. In FIG. 12D, the etchant creates a ridge region 80 and a valley region 82, i.e., a recessed region associated with the location where the etchant was originally applied. Thus, the first major surface 14 after etching according to the disclosure of the present invention can comprise a first low-frequency macroscale anisotropic texture. The substrate can further comprise a fine high-frequency isotropic surface texture imposed across the major surface of the substrate that was in contact with the etchant. Whereas the anisotropic texture includes a peak-to-peak period and size, the isotropic texture is best characterized by an average surface roughness Sa equal to or less than about 1 nanometer, and this anisotropic texture extends across the surface of the substrate to which the etchant was applied and is uniform regardless of the direction in which the characterization is made.

[0081] The processed substrate obtained from the method applied by either the processing device 10 or the processing device 100 can comprise a first texture. Exemplarily, FIG. 13 shows a computer-simulated optical view (e.g., can be imaged through an optical instrument, e.g., a microscope) of a textured substrate surface having the first texture obtained from the processing device 10 or the processing device 100. The first texture can be an anisotropic texture having one direction (in this case, the direction is along an axis orthogonal to a ridge, e.g., a line of ridges similar to a wavefront) as indicated by the large white arrow 164, which extends orthogonally to the transport direction 20 of the substrate 12 and thus to the masking roller 32 (or the etching liquid roller 136) (shown here as -45°). Thus, the direction of the first texture extends in the +45° direction shown in the figure and is continuous along an axis parallel to the rotation axis 48 of the masking roller 32 in the embodiment of the processing device 10 or the rotation axis 132 of the etching liquid roller 136 in the embodiment of the processing device 100. The first texture, e.g., the texture 102 directly related to a plurality of spaced ridges, is shown in the plot of FIG. 14, and the first texture includes a sine wave pattern in this example. However, the first texture does not have to show a sine wave pattern and can show other patterns depending on the configuration of the masking or etching liquid roller ridges (e.g., the processing device 10 or the processing device 100). Referring to FIG. 14, the first texture can have a peak-to-peak period 104 in the range of about 0.1 millimeter to about 100 millimeters, e.g., in the range of about 1 millimeter to about 75 millimeters. The first texture 102 can have a peak-to-valley magnitude 106 in the range of about 2 nanometers to about 100 nanometers.

[0082] The substrate 12 can comprise a second isotropic texture resulting from the overall action of the etching liquid on the exposed first main surface 14 of the substrate 12 and can have uniform characteristics regardless of direction, i.e., an isotropic texture. For example, the second texture can show an average surface roughness Sa equal to or less than about 1 nm when measured by an atomic force microscope (AFM).

[0083] In some embodiments, the first main surface 14 can comprise a third texture 108 juxtaposed with the first texture 102. The third texture 108 can be a low-frequency texture shown as a sine-wave texture in FIG. 15, but the third texture 108 need not be a sine wave, like the first texture 102. The third texture 108 can have a peak-to-peak wavelength 110 in the range of about 0.1 millimeter meter to about 25 millimeter meters. The third texture 108 can have a peak-to-valley magnitude 112 in the range of about 2 nanometers to about 500 nanometer meters. The third texture 108 can, for example, result from the movement of the substrate 12 that is not directly related to the linear movement of the substrate in the conveyance direction 20 (120). That is, when the substrate traverses across the conveyance rollers in the conveyance direction, an incidental movement of the substrate, such as a rocking movement, may occur, whereby the third texture 108 may be generated. Accordingly, the third texture 108 can extend in a -45° direction such that a line extending perpendicular to the successive wavefronts of the third texture 108 is parallel to the conveyance direction 20 (120).

[0084] In some embodiments, the first main surface 14 can comprise a fourth texture 118 shown in FIG. 15 as a high-frequency texture juxtaposed with the third texture 108. An additional fourth texture 118 can be generated by the hydrodynamics associated with the movement of the etchant from the etchant reservoir to the etchant roller and / or from the etchant roller to the first main surface 14 of the substrate 12. The fourth texture 118 can have a peak-to-peak period 122 in the range of about 0.1 nanometers to about 2 nanometers.

[0085] FIG. 16 represents the fast Fourier transform of the simulated texture represented by FIG. 13 and shows the high-frequency components of this transform. The period is given by the formula X (meters) = 2π / X * (meters -1) is related to the frequency, where X is the peak-to-peak period, and X * are the respective frequencies. Therefore, the texture periods 104, 110, and 122 (see FIG. 13) are 300 m -1 , 600 m -1 , and 6000 m -1 at the frequencies 104 * , 110 * , and 122 * respectively.

[0086] A method for characterizing an anisotropic texture on a processed major surface, e.g., the first major surface 14, includes, for example, an optical interference method (e.g., Zygo NexView) that scans a predetermined area of the substrate using a low magnification objective lens. In some embodiments, it may be necessary to scan multiple areas, in which case adjacent scans can be stitched together to obtain the desired full field of view. The resulting image can be processed using an open source image analysis package, e.g., Gwyddion Ver 2.51. For example, the outer edges of the image can be adjusted to address image artifacts and data dropouts. Next, a fourth-order plane fitting can be used to flatten the image by restricting the scale of the Z-axis line (height) to, for example, ±10 nm, making it possible to detect fine morphological changes. If desired, the image can be rotated to align the image to correspond to the glass movement passing through the processing apparatus. Next, the image can be transformed using a fast Fourier transform to enable analysis of the spatial frequency signature.

[0087] Figures 17 through 19 illustrate exemplary masks and etch patterns that can result in (anisotropic) columns of texture on substrate 12. That is, the cross-hatched areas indicate areas of addition either of masking material 66 by processing apparatus 10 or of patterned addition of etchant by processing apparatus 100. It should be apparent from the above description that additional steps can be performed to obtain more complex etch patterns. For example, the substrate 12 can be rotated by a predetermined angle and masked again, after which etching or re-etching can be performed. For example, with respect to processing apparatus 10, substrate 12 can be masked by adding columns of masking material 66 that form parallel rows in a first direction, and then the substrate can be rotated and a second set of columns of masking material added in a second direction that is rotated by a predetermined angle β from the first direction. Angle β can range from about 1° to 90°. FIG. 17 shows angle β as 90° (in which case the two patterns are orthogonal rows). FIG. 18 shows another embodiment in which parallel rows of masking material are deposited such that they are not parallel to the edge of the substrate, e.g., not parallel to the long axis 180 of the substrate. That is, the rows of masking material are deposited with a rotational offset of angle β from axis 180.

[0088] FIG. 19 shows yet another embodiment where the masking material 66 (and thus the location of the subsequent etch regions) or the processing apparatus 100 is such that the etchant liquid 78 is not added in equally spaced columns. This can be achieved, for example, by unevenly spacing the ridges of the masking roller 32 (or the etchant liquid roller 136 in the case of the processing apparatus 100). As described above with respect to the processing apparatus 10, as a result, it should be apparent that a substrate having a ridge region where the masking material 66 is deposited and a recessed region where the masking material is not added is obtained. With respect to the processing apparatus 100, a ridge region is generated where the etchant liquid 78 is not first added by the etchant liquid roller 136, and a recessed region is generated where the etchant liquid 78 is first added by the etchant liquid roller. In either case, any one or two or more of the first through fourth textures described above with respect to the processing apparatus 10 or the processing apparatus 100 can be generated.

[0089] In the alternative process shown in FIGS. 20 through 21, the masking material 66 can be deposited at discrete locations using a spray nozzle. Figure 21Accordingly, the processing apparatus 200 can include a plurality of spray nozzles 202 arranged to extend in the width direction of the substrate 12 when the substrate 12 is conveyed in the conveyance direction 220 along the conveyance path 230. The spray nozzles 202 can be in fluid communication with a common plenum 204, which in turn is in fluid communication with a container 206 that forms a reservoir 207 for the masking material 66. The masking material 66 can include, for example, styrene maleic acid (SMA), although in other embodiments, other masking materials such as acrylates, novolaks (phenol-formaldehyde resins with a formaldehyde to phenol molar ratio of less than 1), or silicones can be used. Although not shown, in yet other embodiments, the spray nozzles 202 can extend in the conveyance direction 220. For example, the spray nozzles 202 can be arranged in an array of orthogonal rows and columns of spray nozzles. The spray nozzles 202 can be in the form of inkjet nozzles that can "print" a very fine high-resolution pattern onto the substrate. The discrete locations can result in a random or pseudo-random pattern such as a regular, periodic, predetermined pattern, or the randomized pattern shown in FIG. 22.

[0090] The processing apparatus 200 can further include a plurality of transport rollers 228 configured to transport the substrate 12 in the transport direction 220 along the transport path 230, and a container 238 that forms a corrosion liquid reservoir 239 for the corrosion liquid 78. The transport rollers 228 can be full-length rollers rotatably mounted and configured to rotate about their respective rotation axes. In this case, the length 288 of the transport rollers in the direction orthogonal to the transport direction 220 can be equal to or greater than the width 90 of the substrate 12 defined between the first and second side edges 24, 26. The transport rollers 228 can be driven rollers. For example, the transport rollers 228 can be coupled to one or more motors (not shown) that rotate the transport rollers about their respective rotation axes to transport the substrate 12 in the transport direction 220 along the transport path 230. In other embodiments, the transport rollers 228 are not driven and can freely rotate about their respective rotation axes individually. In still other embodiments, the processing apparatus 200 can include a combination of driven and non-driven transport rollers 228. The transport rollers 228 are shown positioned below the substrate 12 and thereby supporting the substrate 12 on the first main surface 14. In yet another embodiment, additional transport rollers 228 can be positioned above the substrate 12 and can contact the second main surface 16. For example, the upper transport roller that contacts the second main surface 16 can be a driven roller that propels the substrate 12 in the transport direction 220 over the non-driven lower transport rollers. In some embodiments, one or more pairs of transport rollers can be configured to extend partially in a direction orthogonal to the transport direction 20. For example, in some embodiments, a transport roller such as an upper transport roller (not shown) that contacts the second main surface 16 can contact the edge portion of the substrate 12 and not contact the central portion of the second main surface 16.

[0091] The processing apparatus 200 can further include a corrosion liquid roller 236 positioned along the transport path 230. In some embodiments, the processing apparatus 200 can include a single corrosion liquid roller 236, while in yet other embodiments, the processing apparatus 10 can include a plurality of corrosion liquid rollers 236. The corrosion liquid roller 236 is positioned downstream of the spray nozzle 202 with respect to the transport direction 20, in which case the substrate 12 moving along the transport path 30 in the transport direction 20 encounters the corrosion liquid roller 236 after the spray nozzle 202 deposits the masking material 66 on the first major surface 14. In various embodiments, the corrosion liquid roller 236 can be configured similarly or identically to the corrosion liquid roller 36 of the processing apparatus 10.

[0092] The corrosion liquid roller 236 can extend across all or a part of the width 90 of the substrate 12 in a direction orthogonal to the transport direction 220. That is, the rotation axis 264 of the corrosion liquid roller 36 can be orthogonal to the transport direction 20. The processing apparatus 200 can further include a corrosion liquid circulation system 240 configured to be in fluid communication with a reservoir 239 and circulate the corrosion liquid 78 into the container 238 through a pump 242 and piping 244. In an embodiment, the corrosion liquid roller 236 can be rotatably mounted on top of the container 238 such that the peripheral surface of the corrosion liquid roller 36 contacts, for example, is immersed in the corrosion liquid 78 confined in the container 238. In various embodiments, the corrosion liquid 78 can include hydrofluoric acid (HF), while in yet other embodiments, other suitable corrosion liquids can be used depending on the material of the substrate 12. In the examples described herein, the corrosion liquid 78 includes H3PO4 at a concentration of 1 mole (M) and NaF at a concentration of 0.35 mole at 40°C. However, other suitable corrosion liquids can be used. For example, HF-based etching of glass is initially time-dependent, and the achievable average roughness Ra value ultimately saturates at about 0.5 nm. The resulting surface texture of the processed substrate 12 can be on the nanometer scale both in the lateral direction along with the height, and the correlation length can also be on the nanometer order.

[0093] The above-described embodiments relate to the step of etching the main surface of the substrate 12. However, by replacing the exudate with the etchant 78, it is possible to cause a change in the chemical composition of the surface of the substrate that mimics to some extent the change in the surface texture seen in the etchant using the processing apparatuses 10, 100, or 200. For example, the exemplary embodiment can include a step of transporting the substrate 12 along a transport path in a transport direction, a step of adding a masking material to a first region of the first main surface 14 of the substrate 12 when the substrate is transported, and a step of adding an exudate over the first region of the first main surface 14, where the first main surface 14 has a first chemical composition and the exudate leaches at least one component of the first chemical composition from the first main surface 14. As a result, the concentration of at least one component of the first chemical composition can vary periodically along the first axis with the first spatial period after leaching. Suitable exudates can include, but are not limited to, HCl, H2SO4, HNO3, or a combination thereof. Leachable glass components can include, but are not limited to, Mg (magnesium), Ca (calcium), Sr (strontium), Al (aluminum), and / or B (boron).

[0094] Example A Corning Lotus NXT sample having a thickness of 0.5 mm and an area (per main surface) of 150 mm2 was etched according to the masking technique described herein. The etching was performed using four etching times, and the exposure time to the etchant was varied in 40-second increments from 40 seconds to 160 seconds. The sample was etched at three different speeds of 25 millimeters per second, 65 millimeters per second, and 100 millimeters per second. The surface obtained using the optical interferometry method (Zygo NexView) was analyzed, and a 6x6 image matrix was scanned using the lowest magnification objective lens, and the frames were joined together to provide a total field of view of approximately 32 mm2. The obtained images (see FIG. 13 as an example) were processed using Gwyddion Ver. 2.51 according to the procedure outlined below.

[0095] The most prominent texture features occurred at the longest etching time (160 seconds). Data were also collected from untreated Lotus NXT and substrate samples that had undergone general surface etching with 1 M H3PO4 + 0.35 M NaF at 40 °C for comparison. AFM was performed under each condition to evaluate the nanotexture. All etching conditions showed similar substrate surface characteristics through AFM imaging. Line profiles for all four surfaces are shown in Figure 23. The general etched surface without masking (1 M H3PO4 + 0.35 M NaF) showed a hash pattern with fringes extending along both lines parallel and perpendicular to the movement of the roller. These fringe structures had substantially equal peak-to-valley magnitudes across the surface, with peak-to-peak observed values of approximately +0.4 nanometers and -0.25 nanometers, respectively (Figure 23(a)). Adding masking at a low speed (e.g., 25 millimeters / second) did not significantly change the overall line profile (Figure 23(b)). At higher masking application speeds (65 millimeters / second and 100 millimeters / second), the texture bands became more prominent both visually and through line profile extraction. The frequency in the direction along the roller axis was washed out and became less well-defined. The height difference in the masked regions was also clearly observed in the line profiles shown in Figures 23(c), (d). Some of the texture bands appeared to be added with a slight angular offset relative to other texture bands, and for this reason, the increase in peak-to-valley magnitude (from approximately +1.1 nanometers to approximately -0.8 nanometers) indicates that these regions are merging with each other within the line profile. Other bands were more distinct and were separated by a distance of about a few millimeters within the range of the ridge-valley radius seen on the mask-patterned roller. Preliminary lift test measurements showed that these textures can improve the ESC performance by up to about 12% depending on the addition of masking and the etching speed. The lift test consists of a flat vacuum surface (e.g., a vacuum plate) with a 10 cm × 10 cm stage plate attached, insulating lift pins surrounding the stage plate, and an array of electrostatic field meters suspended above the glass plate surface.The measurement sequence begins by placing the test sample face down on top of a lift pin positioned on a vacuum plate. A high-flow corona discharge ionizer is used to remove any charge remaining on the sample. A vacuum is generated by the Venturi method, and the glass plate is brought into contact with the vacuum surface under a constant and controlled pressure by lowering the sample onto the vacuum plate using the lift pin. This state is maintained for several seconds, after which the vacuum is released and the glass sample plate is raised by the lift pin to a height of approximately 80 cm (about 10 mm below the electrometer array) from the vacuum surface. The voltage of the glass surface is monitored and recorded with an electrometer over a time sufficient to obtain data regarding the maximum voltage generated during the vacuum process and its subsequent decay rate.

[0096] Figure 24 is a plot showing the average % voltage improvement as a function of the characteristic interval, where the characteristic interval is similar to the period of the waveform of the anisotropic texture. The data shown with the confidence intervals represent the rate of change (decrease or increase) of the maximum lift test voltage V (V@lift pin height 80 cm) obtained from the etched sample relative to the untreated unetched sample, providing insight into the electrostatic charging (ESC) of the samples tested. For example, a 0% rate of change represents the same voltage generation as the control sample, a 100% rate represents virtually no surface voltage generation, and a -100% rate represents a doubling of the surface voltage generation compared to the control sample. The tests were conducted in a class 1000 cleanroom and at a relative humidity of 40%, and the apparatus itself was enclosed in an anti-static acrylic housing with a dedicated HEPA air filter. The data indicate that the ESC improvement (Vssavg) increased as the characteristic interval of the anisotropic texture increased over a range, for example, from about 0 mm to about 75 mm.

[0097] It will be apparent to those skilled in the art that various modifications and changes can be made to the embodiments of the disclosure of the present invention without departing from the spirit and scope of the disclosure of the present invention. That is, the disclosure of the present invention is intended to cover such modifications and changes as long as they fall within the scope of the appended claims and their equivalents.

Claims

1. A first main surface comprising a periodic first texture having a first size and a first spatial period along a first axis, the periodic first texture extending along the first axis with a length equal to or greater than twice the first spatial period, and an isotropic second texture juxtaposed with the first texture and having an average surface roughness Sa equal to or less than 1 nanometer. The first size is in the range of 2 nanometers to 500 nanometers. The first main surface further comprises a periodic third texture juxtaposed with the first texture, the third texture having a second size and a second spatial period along a second axis parallel to the first main surface and different from the first axis. The third texture extends along the second axis with a length equal to or greater than twice the second spatial period. A glass substrate, characterized in that.

2. The first spatial period is in the range of 0.1 millimeter to 100 millimeters. The glass substrate according to Claim 1.

3. The second axis is orthogonal to the first axis. The glass substrate according to Claim 1 or 2.

4. The second size is in the range of 2 nanometers to 500 nanometers. The glass substrate according to any one of Claims 1 to 3.

5. The second spatial period is in the range of 0.1 millimeter to 25 millimeters. The glass substrate according to Claim 4.

6. The first main surface further comprises a periodic fourth texture juxtaposed with the third texture, the fourth texture having a third size and a third spatial period along the second axis, the fourth texture extending along the second axis with a length equal to or greater than twice the third spatial period. The glass substrate according to Claim 5.

7. A method for texturing a glass substrate, comprising: Conveying the glass substrate along a conveying path in a conveying direction; Adding a masking material to a first main surface of the glass substrate with a first predetermined pattern when the glass substrate is conveyed. After the step of adding the masking material when the glass substrate is being conveyed, etching the first main surface over a first region of the first main surface, removing the masking material, and adding an etching solution that forms a first texture having a first size and a first spatial period along a first axis in the first region, a second texture on the first main surface having an average surface roughness Sa smaller than 1 nanometer, and a third texture juxtaposed with the first texture, wherein the third texture has a second size and a second spatial period along a second axis different from the first axis. The first size is in the range of 2 nanometers to 500 nanometers. A method characterized by this.

8. The first size is in the range of 2 nanometers to 100 nanometers. The method according to claim 7.

9. The first spatial period is in the range of 0.1 millimeter to 100 millimeters. The method according to claim 8.

10. The first texture is anisotropic. The method according to claim 7.

11. The second texture is isotropic. The method according to any one of claims 7 to 10.

12. The third texture is anisotropic. The method according to any one of claims 7 to 11.

13. The second axis is orthogonal to the first axis. The method according to any one of claims 7 to 12.

14. The etching forms a fourth texture juxtaposed with the first texture, and the fourth texture has a third size and a third spatial period along the second axis. The method according to any one of claims 7 to 13.

Images