Metasurface coating

Abstract

To provide a metasurface coating having a predetermined characteristic including roughness below prescribed maximal roughness.SOLUTION: A method includes providing a coating 208 over a first surface 202 of a substrate 204 and over a metasurface 200 on the first surface 202 of the substrate 204; and imprinting the coating 208 to cause a surface 222 of the coating 208 to have a predetermined characteristic. A device includes a substrate 204; the metasurface 200 on the first surface 202 of the substrate 204; and a coating 208 on the metasurface 200 and on the first surface 202 of the substrate 204, the surface 222 of the coating 208 defining a functional structure.SELECTED DRAWING: Figure 2A-2B

Description

Background Art

[0001] A metasurface is a surface having a distributed nanostructure that can be arranged to interact with light in a specific way. In some cases, the metasurface is covered with a coating. A coating having specific properties can provide beneficial effects.

Summary of the Invention

Means for Solving the Problems

[0002] In one aspect, the present disclosure describes a method including providing a coating on a first surface of a substrate and on a metasurface on the first surface of the substrate, and imprinting the coating such that a surface of the coating has predetermined properties.

[0003] Embodiments of the method can include one or more of the following. Imprinting the coating includes pressing a surface of a stamp into the surface of the coating, the surface including a structure that imparts predetermined properties to the surface of the coating. The predetermined properties include a roughness less than a predetermined maximum roughness.

[0004] In some embodiments, the predetermined properties include an optical structure defined by the surface of the coating. The optical structure includes a diffractive optical structure. The optical structure includes a lens. The optical structure includes an anti-reflection structure. The optical structure includes features having dimensions of 10 nm to 100 nm. The predetermined properties include hydrophobicity or hydrophilicity. Imprinting the coating gives the coating a predetermined thickness.

[0005] In some embodiments, imprinting the coating includes pressing the face of the stamp into the surface of the coating, the face including a spacer, the face being pressed into the surface of the coating until the ends of the spacer contact the first surface of the substrate, the height of the spacer being equal to a predetermined thickness. Imprinting the coating includes pressing the face of the stamp into the surface of the coating, the spacer being on the first surface of the substrate, the face being pressed into the surface of the coating until the ends of the spacer contact the face of the stamp, the height of the spacer being equal to the predetermined thickness.

[0006] In some embodiments, the coating includes a polymer. The metasurface includes nanostructures operable to interact with light waves to change at least one of the amplitude or phase of the light waves. Imprinting the coating includes making the surface of the coating parallel to the first surface of the substrate. The method includes providing a second coating on the second surface of the substrate, the second surface of the substrate being on the opposite side of the first surface of the substrate, and imprinting the second coating such that the surface of the second coating has a second predetermined property.

[0007] The present disclosure also describes a device comprising a substrate, a metasurface on a first surface of the substrate, and a coating on the metasurface and on the first surface of the substrate, the surface of the coating defining a functional structure.

[0008] In some embodiments, the surface of the coating defines an optical functional structure. The optical functional structure includes a diffractive optical structure. The optical functional structure includes an optical lens. The optical functional structure includes an anti-reflection structure. The functional structure includes a hydrophobic structure or a hydrophilic structure. The functional structure includes features having dimensions of 10 nm to 100 nm. The coating includes a polymer.

[0009] In some embodiments, the metasurface includes nanostructures operable to interact with light waves to change at least one of the amplitude or phase of the light waves. The surface of the coating has a roughness less than a predetermined maximum roughness. The device includes a second coating on a second surface of the substrate, the second surface of the substrate being on the opposite side of the first surface of the substrate, and the surface of the second coating defining a second functional structure. The coating has a thickness greater than 10 microns.

[0010] The present disclosure also describes a system comprising a coating deposition apparatus, a stamp aligner, and a controller communicatively coupled to the stamp aligner and the coating deposition apparatus, the system configured to perform operations including providing a coating on a first surface of a substrate and on a metasurface on the first surface of the substrate, and imprinting the coating such that the surface of the coating has predetermined characteristics.

[0011] The present disclosure also describes a module. For example, the module can include a light emitting device and a metasurface device, the metasurface device comprising a substrate, a metasurface on a first surface of the substrate, and a coating on the metasurface and on the first surface of the substrate, the surface of the coating defining a functional structure, the metasurface device configured to interact with light generated by the light emitting device.

[0012] The present disclosure further describes a module comprising a light sensing device and a metasurface device, the metasurface device comprising a substrate, a metasurface on a first surface of the substrate, and a coating on the metasurface and on the first surface of the substrate, the surface of the coating defining a functional structure, the metasurface device configured to interact with light incident on the module and transmit the modified light to the light sensing device.

[0013] Certain embodiments of the subject matter described in this disclosure can be implemented to realize one or more advantages. For example, in some embodiments, the coating can protect the nanostructures underlying the metasurface from mechanical damage. In some embodiments, the coating may be composed of cost-effective materials. In some embodiments, imprinting the coating is a cost-effective means of surface modification compared to alternative manufacturing methods. In some embodiments, the coating can protect the metasurface from chemical reactions. In some embodiments, the surface of the coating can incorporate optical functions, non-optical functions, or both optical and non-optical functions. In some embodiments, a more uniform coating thickness can be maintained across the substrate surface. In some embodiments, the coating surface can be made to have lower roughness and / or higher flatness. In some embodiments, when multiple coatings are provided on the metasurface, specific properties can be imparted to the coating surface. In some embodiments, the coating may be provided on multiple surfaces of the substrate.

[0014] Details of one or more embodiments are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages will be apparent from the description and drawings, and from the claims.

Brief Description of the Drawings

[0015]

Figure 1A

Figure 1B

Figure 1C

Figure 1D

Figure 2A

Figure 2B

Figure 3A

Figure 3B

Figure 4

Figure 5A

Figure 5B

Figure 6A

Figure 6B

Figure 7

Figure 8

[0016] The present disclosure relates to a coating formed on a metasurface. In certain embodiments, the present disclosure describes imprinting a coating formed on a metasurface so that the surface of the coating has predetermined characteristics.

[0017] A metasurface is a surface having a dispersed array of nanostructures. The nanostructures can interact with light waves, either individually or collectively. For example, the nanostructures can change the local amplitude, local phase, or both of the incident light wave.

[0018] When the nanostructures are arranged in a specific pattern, the metasurface can act as an optical element such as a lens, a lens array, a beam splitter, a diffuser, a polarizer, or other optical elements. In some cases, the metasurface can perform optical functions conventionally carried out by refractive and / or diffractive optical elements. However, the metasurface can also perform other functions including polarization control, negative refractive index transmission, beam deflection, vortex generation, polarization conversion, optical filtering, and plasmonic optical functions.

[0019] The nanostructures can be mechanically delicate. For example, nanostructures on the surface of a substrate can be detached from the substrate by mechanical stress (e.g., scraping along the surface, or pressure applied to the nanostructures towards the substrate). In some cases, the nanostructures can also be chemically unstable, so the nanostructures react with their surrounding environment in an undesirable way (e.g., oxidize when in contact with water or atmospheric oxygen).

[0020] Furthermore, contaminants on the nanostructures can mechanically and / or chemically damage the nanostructures or impair the proper optical functions of the nanostructures. Malfunctioning nanostructures can lead to non-operational devices and, in addition, can compromise safety. For example, a laser beam can be deflected into a user's eye by a water droplet on the metasurface. As another example, a wet metasurface has a changed refractive index surrounding the metasurface, and the changed refractive index changes the optical properties of the metasurface, resulting in collimated light passing through the metasurface and entering the user's eye.

[0021] Therefore, in some cases, it may be beneficial to apply a protective coating to the metasurface and further perform processing steps on the coating to impart predetermined properties to the coating.

[0022] As shown in FIG. 1A, some embodiments include a metasurface 100 on a surface 102 of a substrate 104. The metasurface 100 includes a plurality of individual nanostructures 106.

[0023] Each nanostructure 106 may be, for example, a protruding post or other structure having a predetermined shape. In some embodiments, the nanostructure 106 is L-shaped, V-shaped, and / or U-shaped. In some embodiments, the nanostructures 106 are arranged in a two-dimensional (2D) array on the substrate surface 102 In some embodiments, the nanostructure 106 is a strip arranged in a one-dimensional (1D) array on the substrate surface 102. In some embodiments, the nanostructures 106 are arranged in other patterns, such as concentric rings. In some cases, each nanostructure 106 can function, for example, as an antenna.

[0024] Each nanostructure 106 can have dimensions, for example, on the order of tens of nanometers (nm) or hundreds of nm. In some embodiments, each nanostructure 106 has dimensions in the range of 10 nm to 100 nm. In some embodiments, each nanostructure 106 has dimensions in the range of 100 nm to 500 nm. In some embodiments, each nanostructure 106 has dimensions less than 1 μm. In some embodiments, each nanostructure 106 has dimensions less than 10 μm. The dimensions of the nanostructures can be different in other embodiments.

[0025] The metasurface 100 can be manufactured, for example, using additive lithography, subtractive lithography, or both. The metasurface 100 can include, for example, one or more of a plasmonic material (e.g., aluminum-doped zinc oxide), a semiconductor (e.g., silicon), and a dielectric (e.g., silicon oxide).

[0026] The substrate 104 may be, for example, a semiconductor substrate such as a silicon wafer. In some embodiments, the substrate 104 is a flexible substrate, such as plastic.

[0027] In some embodiments, substrate 104 includes other features and structures not shown in FIG. 1A. For example, substrate 104 can include a laser that generates light that interacts with metasurface 100. As another example, substrate 104 can include an on-chip waveguide that directs light toward metasurface 100.

[0028] As shown in FIG. 1B, coating 108 is provided over substrate surface 102 and over metasurface 100.

[0029] In some embodiments, coating 108 is a polymer deposited by spin coating. In some embodiments, coating 108 is deposited using spray deposition, dip coating, printing, or a vapor deposition process (e.g., chemical vapor deposition or physical vapor deposition). Coating 108 can include, for example, one or more of a polymer, spin-on glass, nanoparticles dispersed in a solvent, another spin-coatable material, or a material deposited by means other than spin coating.

[0030] Materials other than polymers can also be used for coating 108. If coating 108 is imprinted, the material can be a material that is deposited soft and then becomes hard (or can become hard). If coating 108 is not processed using imprinting, coating 108 can be any material that is sufficiently physically and chemically resistant, has optical properties that do not interfere with the proper operation of metasurface 100, and has a surface that can be functionalized, as described below.

[0031] Coating 108 may be composed of a material having specific characteristics. For example, coating 108 may be optically transparent in either a broadband or narrowband suitable for a specific function (e.g., transparent in the optical band where the underlying metasurface 100 is optically operable). Coating 108 may be chemically and / or physically resistant and durable to protect the underlying metasurface 100. Coating 108 may be relatively chemically impermeable to prevent ambient chemicals (e.g., atmospheric oxygen) from penetrating the coating 108 and chemically interacting with the metasurface 100. Coating 108 may be electrically insulating. Coating 108 may be thermally insulating or thermally conductive (e.g., if coating 108 is thermally conductive, the coating can improve the cooling of the device). Conductive (e.g., if coating 108 is thermally conductive, the coating can improve the cooling of the device).

[0032] After providing coating 108, coating 108 can be characterized by one or more parameters. For example, the surface 110 of the coating can be characterized by a roughness (e.g., root mean square roughness) representing the typical roughness across the coating surface 110. Surface roughness is mostly inevitable at this point in the manufacturing process and can be inherent, for example, in the coating deposition method used or the choice of coating material. A coating surface 110 with too high a roughness may cause undesirable optical effects, such as deflection or reflection. The coating surface 110 may have a roughness, for example, exceeding the desired maximum roughness.

[0033] After providing coating 108, coating 108 can also be characterized by one or more thicknesses 112. Coating 108 may have a substantially the same thickness 112 across coating 108, or the thickness 112 may vary. For example, in embodiments where coating 108 is deposited by spin coating, the thickness 112 may vary along the radius of the spin. In some embodiments, as-deposited coating 108 can have a uniform thickness 112 that is difficult to precisely control. Coating 108 having an undesirable thickness 112 or a non-uniform thickness 112 can cause undesirable optical effects, such as reflection.

[0034] Due to the structure underlying coating 108, coating 108 can have various thicknesses 112 and / or high roughness. For example, when coating 108 is deposited using vapor deposition, coating 108 can conformally coat a rough or non-uniform surface underlying coating 108 such that coating 108 itself has a rough or non-uniform thickness.

[0035] In some embodiments, to control at least the roughness and / or thickness of coating 108, as shown in FIG. 1C, coating 108 is imprinted using stamp 114. The surface 116 of stamp 114 contacts the coating surface 110, and stamp 114 is pressed toward the substrate surface 102. The imprint can impart a predetermined or specified characteristic to the coating surface 110.

[0036] In some embodiments, the stamp 114 is pressed against the substrate surface 102 at a predetermined pressure or to a predetermined spatial extent. In some embodiments, the stamp 114 is heated before or during imprinting such that the stamp 114 becomes hot during imprinting. This causes the coating 108 to soften and be more easily shaped by the stamp 114. In some embodiments, the coating 108 is hot during imprinting. In some embodiments, the stamp is pressed against the coating 108 for a predetermined amount of time. In some embodiments, for example, ultraviolet (UV) imprinting can be used as an alternative to thermal imprinting. UV imprinting generally involves applying UV radiation to cure the coating after pressing the stamp into the coating 108 while the coating is in a deformable state.

[0037] As shown in FIG. 1D, when the stamp 114 is removed after imprinting, the coating 108 has a relatively smooth coating surface 111. The smooth coating surface 111 is imparted by the corresponding smooth surface 116 of the stamp 114, i.e., the structure of surface 116 imparts a corresponding structure to the coating 108. After imprinting, the coating surface 111 may be sufficiently smooth such that the post - imprint coating surface 111 has a roughness less than, for example, a desired specified maximum roughness. In some embodiments, the roughness is sufficiently small so as not to degrade the desired optical function of the device, e.g., by unwanted light scattering. In some embodiments, the roughness is less than 50 Å RMS, less than 20 Å RMS, less than 10 Å RMS, less than 5 Å RMS, less than 1 Å RMS, or less than 0.1 Å RMS.

[0038] The roughness can be characterized at portions of the coating surface 111 that do not include structures intentionally defined by the surface of the coating, as described below in connection with FIGS. 2A - 2B.

[0039] In some embodiments, the imprint provides an optically flat surface. For example, if λ is the wavelength of light to which the metasurface is configured to interact, the coated surface 111 can have a flatness of less than λ, less than λ / 2, less than λ / 4, less than λ / 20, or less than λ / 100.

[0040] After imprinting, the coating 108 can also have a defined thickness 113 corresponding, for example, to the distance by which the stamp 114 is pressed towards the substrate surface 102. In some embodiments, the defined thickness 113 corresponds to the minimum distance between the surface 116 of the stamp 114 and the substrate surface 102 during imprinting.

[0041] In some embodiments, the thickness 113 is greater than 1 micron. For example, in some embodiments, the coating 108 has a thickness 113 of 1 micron to 10 microns. In some embodiments, the thickness 113 is greater than 10 microns. For example, in some embodiments, the thickness 113 is 10 microns to 50 microns. In some embodiments, the thickness 113 is greater than 50 microns. In some embodiments, the thickness 113 is optically thick, e.g., thicker than some wavelengths of light that interact with the metasurface 100.

[0042] In some embodiments, the coating 108 is less than 1 micron. In some embodiments, the coating 108 is an antireflection coating, e.g., a 1 / 4 wavelength antireflection coating.

[0043] In some embodiments, the coating 108 provides an optical effect that can modify the optical function of the metasurface 100. For example, the coating 108 can have a refractive index that changes the interaction between light and the metasurface 100. The metasurface 100 may be designed to take into account the optical effect caused by the coating 108.

[0044] In some embodiments, after imprinting, the coating surface 111 is substantially parallel to the substrate surface 102. Thereby, the light incident on the coating surface 111 may be less deflected with respect to the metasurface 100 than when the coating surface 111 is non-parallel to the substrate surface 102.

[0045] In some embodiments, the coating 108 is cured or otherwise strengthened before imprinting, after imprinting, or both before and after imprinting. Curing can include, for example, thermal curing or optical curing (e.g., ultraviolet (UV) curing).

[0046] In some embodiments, the deposition of the polymer coating and the imprinting of the polymer coating can be faster and / or more cost-effective than alternative materials and / or manufacturing techniques. For example, the polymer coating may be deposited over the entire wafer, and the stamp may imprint the coating over the entire wafer in a single imprint step to produce a uniform coating thickness at the wafer scale. The wafer can then be diced into individual devices. In contrast, some other manufacturing techniques (e.g., photolithography performed on a polymer coating or photolithography performed on a non-polymer coating) can be slower and / or more expensive. In combination with the imprint process described in this disclosure, the polymer coating can be particularly advantageous because at least the polymer coating can be deposited in a malleable (e.g., soft) state that facilitates imprinting. In some embodiments, the coating 108 is provided only on a portion of the substrate 104. In some embodiments, a portion of the coating 108 is removed from a portion of the substrate 104.

[0047]

[0048] ​Figures 2A-2B illustrate a process for providing a functional coating on a metasurface. In Figure 2A, the metasurface 200 is on the substrate surface 202 of the substrate 204. The coating 208 is on the metasurface 200 and the substrate surface 202 and may be provided, for example, using the method described above for coating 108.

[0049] The stamp 214 is used to imprint the coating 208 to fabricate the device shown in Figure 2B. The surface 216 of the stamp has a structure incorporating features 218, and the imprint imparts features 220 corresponding to the coating surface 222 shown in Figure 2B. Each feature 218 defined by the surface 216 of the stamp can have dimensions of tens or hundreds of nanometers (e.g., depth or lateral width). In some embodiments, each feature 218 has dimensions of 10 nm to 100 nm. In some embodiments, each feature 218 has dimensions of 100 nm to 500 nm. In some embodiments, each feature 218 has dimensions of less than 1 μm. In some embodiments, each feature 218 has dimensions of less than 10 μm. The foregoing dimensions can be different in other embodiments.

[0050] The features 220 define a patterned structure 224 having one or more functions. In some embodiments, the function is an optical function. For example, the patterned structure 224 can include a diffractive optical element. The patterned structure 224 can include one or more of a beam splitter, a diffractive lens, a microlens, a light diffuser, or another optical device (or, equivalently, perform one or more of their functions). For example, in the case of a diffractive lens, the patterned structure 224 can include concentric rings of features 220 having various heights and widths configured to minimize aberration and / or directly focus light.

[0051] The patterned structure 224 itself may be a metasurface. For example, each feature 220 may be a nanostructure, and the features 220 may interact with light waves individually or collectively. In some cases, the features 220 may be able to change the local amplitude, local phase, or both of the incident light wave. Each feature 220 can have dimensions of several tens of nm or several hundreds of nm. In some embodiments, each feature 220 has dimensions of 10 nm to 100 nm. In some embodiments, each feature 220 has dimensions of 100 nm to 500 nm. In some embodiments, each feature 220 has dimensions of less than 1 μm. In some embodiments, each feature 220 has dimensions of less than 10 μm. The aforementioned dimensions may be different in some other embodiments.

[0052] Furthermore, in some cases, each feature 220 can have dimensions smaller than the wavelength of the light that interacts with the metasurface 200. Furthermore, in some cases, each feature 220 can have dimensions similar to those of the nanostructures 206 of the metasurface 200.

[0053] The functions of the patterned structure 224 can include diffraction and anti-reflection. For example, the patterned structure 224 can include a diffraction grating. The patterned structure 224 can include surface texturing that provides anti-reflection properties. For example, each feature 220 may be a pyramid, and as a result, the coating 208 is an anti-reflection coating based on pyramids that reflect light after imprinting.

[0054] In some embodiments, the coating 208 is thinner than a conventional optical system configured to provide the optical function of the coating 208. For example, the patterned structure 224 can include a lens, and the coating 208 can be made thinner than an individual lens having the same optical effect as the lens of the patterned structure 224. By reducing the required height of the device including the coating 208, the coating 208 can provide a space-saving advantage.

[0055] In some embodiments, the patterned structure 224 has a non-optical function. For example, the patterned structure 224 may be hydrophobic (e.g., including an array of posts that reduce the contact area of a liquid on the coating surface 222). The patterned structure 224 may be hydrophilic. The patterned structure 224 may be self-cleaning (e.g., including nanostructures for forming a hydrophobic surface).

[0056] In addition to including the patterned structure 224, the post-imprint coating 208 may have a set thickness 213 defined by the imprint process as described with reference to FIGS. 1A-1D.

[0057] FIG. 2B shows the same feature 220 defined by the coating surface 222, but in some embodiments, there are various different features defined by the coating surface, and the features perform multiple functions individually or collectively.

[0058] As used in this disclosure, "imprint" should be understood to include the surface of the coating on the metasurface and other processes that can make the substrate surface have predetermined characteristics, as shown in FIGS. 1D and 2B. For example, "imprint" can include one or more of embossing, debossing, and nanoimprint. Although this disclosure shows an example of a stamp moving towards the substrate, in some embodiments, the substrate moves towards the stamp.

[0059] Furthermore, although the devices shown in FIGS. 1D, 2B, and throughout this disclosure are described as being manufactured using an imprint process, the devices themselves are the subject of this disclosure. A device that includes a substrate, a metasurface on the surface of the substrate, and a coating on the metasurface and on the surface of the substrate provides advantages and can have the features described elsewhere in this disclosure regardless of the method of manufacturing the device. For example, the surface of the coating can define a functional structure as described elsewhere in this disclosure. The coating can be manufactured using a non-imprint method while remaining within the scope of the devices described in this disclosure.

[0060] In some embodiments, the stamp 214 is made of silicon and / or glass. In some embodiments, the stamp 214 is a working stamp (e.g., a nickel shim) having a structure established by a master stamp.

[0061] In some embodiments, the device includes respective coatings on each of the opposite sides of the substrate. As shown in the example of FIG. 3A, the metasurface 300 is on a first substrate surface 302 of the substrate 304. A first coating 308 is on the metasurface 300 and the first substrate surface 302, and a second coating 326 is on a second opposite substrate surface 328. The coatings 308 and 326 may be deposited, for example, using the methods described above for the coating 108. In some embodiments, the coatings 308 and 326 are deposited simultaneously, for example, using a dip coating method.

[0062] As described above, stamps 314 and 315 each having a stamp surface 316, 334 are used to imprint coatings 308 and 326. In some embodiments, stamps 314 and 315 are implemented using the same stamp, and the imprinting of the respective substrate surfaces 302, 328 is performed continuously. In some embodiments, stamps 314 and 315 are different stamps. In some embodiments, the imprinting of the respective substrate surfaces 302, 328 is performed simultaneously.

[0063] FIG. 3B shows a device including coatings 308 and 326 on both substrate surfaces 302, 328, where coatings 308, 326 each have a coating surface 322, 330, each having its respective predetermined characteristics. Coating surfaces 322, 330 define respective patterned structures 324, 332. Patterned structures 324, 332 each include features 325, 333. In some embodiments, since stamp surfaces 316, 334 are substantially the same as each other, features 325, 333 and patterned structures 324, 332 are substantially the same as each other and have substantially the same function. In some embodiments, as shown in FIGS. 3A - 3B, stamp surfaces 316, 334 are different, and the resulting patterned structures 324, 332 include different features.

[0064] Each patterned structure 324, 332 can have a function as described above with reference to FIG. 2B. Each function may be the same as or different from each other.

[0065] In some embodiments, coatings 308, 326 have respective defined thicknesses 313, 317 that may be the same as or different from each other.

[0066] By providing coatings on both substrate surfaces such that the coatings have surfaces with predetermined characteristics, the functionality of the device can be improved. The potential benefits of the coating on the metasurface 300 have been described above. The second coating 326 on the second substrate surface 328 may also provide benefits. For example, the coated surface can include an anti-reflection function. The coated surface can include a hydrophobic function, and / or the second coating 326 can be chemically and / or physically resistant to protect the substrate 304 and, by extension, the metasurface 300. The coated surface may have other optical functions as described above.

[0067] Figures 3A - 3B show a metasurface only on the first substrate surface 302, but in some embodiments, the metasurface may be on both substrate surfaces 302, 328.

[0068] In some embodiments, as shown in FIG. 4, the device includes a plurality of coatings on a substrate surface. The metasurface 400 is on the substrate surface 402 of the substrate 404. The first coating 408 is on the metasurface 400 and on the substrate surface 402, and a second, different coating 436 is on the first coating 408.

[0069] In some embodiments, each coating 408, 436 is provided and processed as described above. For example, the first coating 408 may be spin-coated and then imprinted, and then the second coating 436 may be spin-coated and then imprinted. Either or both of the coatings 408, 436 may have surfaces with predetermined characteristics.

[0070] However, in some embodiments, coatings 408, 436 are provided and / or processed in different ways. For example, in some embodiments, the first coating 408 is a thin anti-reflection coating. For example, the first coating 408 may include silicon oxide or silicon nitride and may be, for example, a 1 / 4 wavelength anti-reflection coating. In some embodiments, the first coating 408 includes multiple layers.

[0071] In some embodiments, coatings 408, 436 are composed of different materials from each other. In some embodiments, coatings 408, 436 have similar refractive indices. In some embodiments, coatings 408, 436 have different refractive indices and can, for example, together form a multilayer anti-reflection coating. In some embodiments, coatings 408, 436 together form a bandpass optical filter, a high or low optical filter, a notch optical filter, or a line optical filter.

[0072] In some embodiments, the first coating 408 is deposited by a deposition technique, such as chemical vapor deposition or atomic layer deposition. Since at least deposition can result in a conformal film having a substantially constant thickness with respect to the underlying structure, the surface 410 of the first coating 408 may be relatively rough, for example, have a roughness exceeding the desired maximum roughness, or have thickness variations. As described above, this may compromise the operability and / or safety of the device. The first coating 408 may have a relatively high roughness or thickness variation even if the first coating 408 is not deposited by a deposition technique.

[0073] The second coating 436 (e.g., a polymer) may be provided and made to have a surface with predetermined characteristics, for example, by imprinting the second coating 436. The predetermined characteristics may be one or more of a roughness less than a desired maximum roughness, a structure having an optical function, a structure having a non-optical function, and a structure having a specific feature size, as described above. Thus, in some cases, the second coating 436 can improve the optical function of the device regardless of possible thickness variations and roughness of the first coating 408.

[0074] In some embodiments, multiple coatings may be on one or more surfaces of a substrate having at least one coating on multiple surfaces, and / or three or more coatings may be on the substrate surface. For example, one or more additional coatings may be on coatings 308 and 326 of FIG. 3B.

[0075] In some embodiments, spacers are provided to define the coating thickness. As shown in FIGS. 5A - 5B, the metasurface 500 is on the substrate surface 502 of the substrate 504. The coating 508 is on the metasurface 500 and on the substrate surface 502. The stamp 540 includes a spacer 542 having a height 544.

[0076] In some embodiments, the spacer 542 is composed of the same material as the rest of the stamp 540. In some embodiments, the spacer 542 is composed of a different material. The spacer 542 can be designed not to deform or break under the pressure that the spacer may be subjected to during imprinting.

[0077] When imprinting the coating 508 using the stamp 540, the distal end 546 of the spacer 542 contacts the substrate surface 502. Thus, after imprinting, the coating 508 has a thickness 513 that is substantially equal to the height 544 of the spacer 542. The use of one or more spacers can help enhance the uniformity of the coating thickness across the substrate 504. This can be useful for.

[0078] In some embodiments, the portion 548 of the substrate surface 502 that contacts the spacer 542 is left with little or no coating 508 after imprinting. This feature can optically separate portions of the metasurface 500 on different sides of the portion 548.

[0079] In some embodiments, the stamp 540 includes, for example, a plurality of spacers 542 spaced apart across the stamp 540. The presence of the plurality of spacers 542 enables, for example, a coating on a large substrate to be imprinted and a common coating thickness to be achieved across the substrate. In some embodiments, as shown in FIGS. 5A - 5B, the stamp 540 is aligned with the substrate 504 such that the portion 548 of the substrate surface 502 where the spacers 542 contact does not have the metasurface 500.

[0080] In some embodiments, the portion 548 defines a line between separate devices. For example, the nanostructure 550 may be part of a first device and the nanostructure 552 may be part of a second device. In some embodiments, the portion 548 may be aligned with a dicing track.

[0081] In some embodiments, the stamp 540 includes trenches near the spacers 542. During imprinting, the trenches can provide a space into which excess coating material can be induced. Since the trenches can be located between devices (e.g., at the portion 548), the accumulation of coating material in the trenches does not impair the function of the devices.

[0082] In some embodiments, as shown in FIGS. 6A - 6B, a spacer 654 is provided on a substrate 604. A metasurface 600 is on a substrate surface 602, and a coating 608 is on the metasurface 600 and on the substrate surface 602. The spacer 654 may be formed as part of the manufacturing process that also forms the metasurface 600. In some embodiments, the spacer 654 is formed during a process separate from the metasurface 600.

[0083] A stamp 656 is used to imprint the coating 608 such that the distal end 658 of the spacer 654 contacts the face 660 of the stamp 656. After imprinting, the coating 608 has a thickness 613 that is substantially equal to the height of the spacer 654. The use of one or more spacers can help enhance the uniformity of the coating thickness across the substrate 604.

[0084] In some embodiments, the substrate 604 includes a plurality of spacers 654 that are spaced apart across the substrate 604, for example. In some embodiments, the spacers 654 define a line between separate devices. For example, the nanostructure 662 may be part of a first device and the nanostructure 664 may be part of a second device. In some embodiments, the spacers 654 may be aligned with a dicing track.

[0085] In some embodiments, the stamp 656 includes trenches configured to be located near the spacers 654. During imprinting, the trenches can provide a space into which excess coating material can be directed. Since the trenches can be located between devices, the accumulation of coating material in the trenches will not impair the function of the devices.

[0086] The methods and devices shown in FIGS. 5A - 6B that include spacers can be combined with the methods and devices described above. For example, imprinting with a spacer can make the coating surface have a specific roughness. Imprinting with a spacer can make its surface It may be performed on either or both of two coatings on two respective opposing surfaces of a substrate having a metasurface on at least one of them. One or both of the two opposing surfaces of the substrate can include one or more respective spacers. Imprinting using the spacers may be performed on one or more coatings within a multi - coating stack.

[0087] The methods and devices described in this disclosure may be implemented in a system. FIG. 7 shows an example of a system 701 that includes a metasurface 700 on a substrate surface 702 of a substrate 704. A coating deposition apparatus 766 is operable to deposit a coating on the substrate. A stamp aligner 768 is operable to align a stamp with the substrate 704 and perform an imprint on the coating. The coating deposition apparatus 766 and the stamp aligner 768 are configured to perform at least the methods described above. A controller 770 communicates with one or both of the coating deposition apparatus 766 and the stamp aligner 768 and is operable to send instructions 772 for performing the deposition and / or imprint process.

[0088] In some embodiments, the alignment is performed with reference to the metasurface 700. In some embodiments, the alignment is performed with reference to spacers (not shown in FIG. 7) on the substrate. In some embodiments, the alignment is performed with reference to other features on the substrate that can be formed, for example, by photolithography. In some embodiments, the alignment and / or imprint is automated (e.g., performed by the stamp aligner 768). The controller 770 can be programmed using process parameters, such as the spin frequency used to spin on the coating, or the pressure applied during the imprint process. In some embodiments, one or more steps are performed manually.

[0089] In some embodiments, a silicon wafer having a metasurface on a first wafer surface is moved along an assembly line. The wafer is immersed in a liquid bath containing a liquid polymer, and a coating is formed on each of the first wafer surface and the second opposite wafer surface. The wafer is held in place while a stamp aligner scans the first wafer surface for alignment features, aligns a hot first stamp based on the alignment features, and lowers the first stamp towards the first wafer surface with a predetermined pressure. The spacer on the first stamp sets the final height of the coating on the first wafer surface, and the features on the face of the first stamp cause the surface of the coating on the first wafer surface to include textured pyramids that reduce the reflection of incident light.

[0090] In an exemplary process, the wafer is then rotated (e.g., by a robotic arm), and a stamp aligner, or a different stamp aligner, performs a second imprint process on the coating on the second wafer surface. The second stamp and parameters of the second imprint process may be the same as or different from the first stamp and parameters of the first print process.

[0091] In an exemplary process, after the two imprint processes are completed, the wafer passes through a UV chamber to cure the two coatings. The underlying metasurface is protected by the coating, and further, the coating provides additional functionality. The wafer can then be diced into individual devices.

[0092] In some embodiments, as described above, a device incorporating one or more metasurfaces and one or more coatings on the metasurface can be integrated into a module. As shown in FIG. 8, the module 874 includes a substrate 876 and a light-emitting component 878 coupled or integrated with the substrate 876. The light-emitting component 878 can include, for example, a laser (e.g., a vertical cavity surface emitting laser) or a light-emitting diode. The light-emitting component 878 can include, for example, a laser (e.g., a vertical cavity surface emitting laser) or a light-emitting diode.

[0093] The light 880 generated by the light-emitting component 878 passes through the housing and is then transmitted to the coated meta-surface device 884. As described above, the coated meta-surface device 884 is operable to modify the light 880 such that the modified light 886 is sent out from the module 874. For example, the module 874 can use the coated meta-surface device 884 to generate one or more of structured light, diffused light, and patterned light. The housing can include, for example, a spacer 882 that separates the light-emitting component 878 and / or the substrate 876 from the coated meta-surface device.

[0094] When incorporated into the module 874, the coated meta-surface device 884 can provide advantages over a device without a coated meta-surface. For example, the coating on the meta-surface can enhance eye safety by reducing the effect of contaminants on the surface of the device 884. The coating can make the module 874 more efficient by having an anti-reflection function, making it less likely for the generated light 880 to be reflected and more likely to be transmitted as the modified light 886. The coating can make the module 874 more stable by protecting the device 884 in adverse environments. The coating may have an optical function that acts to modify the light 880 to produce the modified light 886. The coating can make the device 884 thinner than if individual optical components were to replace the coating, saving space within the module 874 and / or reducing the overall size required for the module 874.

[0095] In some embodiments, module 874 of FIG. 8 is a light detection module (e.g., an ambient light sensor), component 878 is a light detection component (e.g., a photodiode, pixel, or image sensor), light 886 is light incident on module 874, and light 880 is light modified by coated metasurface device 884. For example, coated metasurface device 884 can focus patterned light onto light detection component 878. As described above, the coating on coated metasurface device 884 can reduce the size of module 874 compared to conventional optical systems, protect device 884 in adverse environments, and increase the detection efficiency of module 874 by reducing the amount of reflected light.

[0096] In some embodiments, module 874 can include both a light emitting component and a light detection component. For example, module 874 can emit light that interacts with the environment of module 874 and is then received again by module 874, enabling module 874 to function as, for example, a proximity sensor or a 3D mapping device. When incorporated into such a module, the coated metasurface device can provide the advantages described for the above modules.

[0097] The modules described above may be part of, for example, a time-of-flight camera and an active stereo camera. The modules may be integrated into a system, such as a mobile phone, laptop, wearable device, and automobile.

[0098] According to embodiments of the present disclosure, improved methods and devices are described for depositing a coating on a metasurface and imprinting the coating to give the surface of the coating predetermined characteristics.

[0099] The various aspects of the subject matter and functional operations described in this specification include digital electronic circuits, or computer software, including the structures disclosed herein and their structural equivalents. , can be implemented in firmware, hardware, or a combination of one or more of them. Thus, aspects of the subject matter described herein can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer-readable medium for execution by, or to control the operation of, a data processing apparatus. The computer-readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter that provides a machine-readable propagated signal, or a combination of one or more of them. The apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware.

[0100] A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language including a compiled or interpreted language, and can be deployed in any form, including as a stand-alone program, or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. The program can be stored in a part of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple cooperating files (e.g., files that store one or more modules, subprograms, or portions of code). A computer program can be deployed to be executed on one computer, or on one site, or distributed across multiple sites and executed on multiple computers interconnected by a communication network.

[0101] The processes and logical flows described in this specification can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating input data to produce output. The processes and logical flows can also be performed by, for example, dedicated logic circuits such as FPGAs (Field Programmable Gate Arrays) or ASICs (Application Specific Integrated Circuits), and the apparatus can also be implemented as dedicated logic circuits.

[0102] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, as well as any one or more processors of any kind of digital computer. In general, a processor receives instructions and data from a read only memory or a random access memory or both. Essential elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices such as EPROM, EEPROM, and flash memory devices, magnetic disks, such as internal hard disks or removable disks, magneto-optical disks, and CD-ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, dedicated logic circuits.

[0103] Although particular embodiments have been described in detail, various modifications can be made. As one example, the processes shown in the figures do not necessarily require the particular order, or sequential order, shown to achieve desirable results. In certain embodiments, multitasking and parallel processing may be advantageous. Accordingly, other embodiments are within the scope of the claims.

Claims

1. providing a coating on a first surface of a substrate and on a metasurface on the first surface of the substrate; imprinting the coating such that a surface of the coating has predetermined characteristics; A method comprising:

2. Imprinting the coating comprises: pushing a surface of a stamp into the surface of the coating, the surface comprising a structure that imparts the predetermined characteristics to the surface of the coating, the method according to claim 1.

3. The method according to claim 1, wherein the predetermined characteristics include roughness less than a predetermined maximum roughness.

4. The method according to claim 1, wherein the predetermined characteristics include an optical structure defined by the surface of the coating.

5. The method according to claim 4, wherein the optical structure includes a diffractive optical structure.

6. The method according to claim 4, wherein the optical structure includes a lens.

7. The method according to claim 4, wherein the optical structure includes an anti-reflection structure.

8. The method according to claim 4, wherein the optical structure includes features having dimensions from 10 nm to 100 nm.

9. The method according to claim 1, wherein the predetermined characteristics include hydrophobicity or hydrophilicity.

10. Imprinting the coating comprises providing the coating with a predetermined thickness, the method according to claim 1.

11. Imprinting the coating comprises: pushing a surface of a stamp into the surface of the coating, the surface including a spacer, the surface being pushed into the surface of the coating until an end of the spacer contacts the first surface of the substrate, the height of the spacer being equal to the predetermined thickness, the method according to claim 10.

12. Imprinting the coating comprises: pushing a surface of a stamp into the surface of the coating, the spacer being on the first surface of the substrate, the surface being pushed into the surface of the coating until an end of the spacer contacts the surface of the stamp, the height of the spacer being equal to the predetermined thickness, the method according to claim 10.

13. The method according to claim 1, wherein the coating includes a polymer.

14. The method according to claim 1, wherein the metasurface includes a nanostructure operable to interact with light waves to change at least one of an amplitude or a phase of the light waves.

15. Imprinting the coating comprises making the surface of the coating parallel to the first surface of the substrate. The method according to claim 1. The method according to claim 1, wherein imprinting the coating comprises making the surface of the coating parallel to the first surface of the substrate.

16. Providing a second coating on a second surface of the substrate, the second surface of the substrate being on the side opposite to the first surface of the substrate, and Imprinting the second coating such that the surface of the second coating has a second predetermined property. The method according to claim 1. The method according to claim 1, comprising providing a second coating on a second surface of the substrate, the second surface of the substrate being on the side opposite to the first surface of the substrate, and imprinting the second coating such that the surface of the second coating has a second predetermined property.

17. A substrate, A metasurface on a first surface of the substrate, and A coating on the metasurface and on the first surface of the substrate, the surface of the coating defining a functional structure. A device comprising. A device comprising a substrate, a metasurface on a first surface of the substrate, and a coating on the metasurface and on the first surface of the substrate, the surface of the coating defining a functional structure.

18. The device according to claim 17, wherein the surface of the coating defines an optical functional structure.

19. The device according to claim 18, wherein the optical functional structure comprises a diffractive optical structure.

20. The device according to claim 18, wherein the optical functional structure comprises an optical lens.

21. The device according to claim 18, wherein the optical functional structure comprises an anti-reflection structure.

22. The device according to claim 17, wherein the functional structure comprises a hydrophobic structure or a hydrophilic structure.

23. The device according to claim 17, wherein the functional structure comprises features having dimensions in the range of 10 nm to 100 nm.

24. The device according to claim 17, wherein the coating comprises a polymer.

25. The device according to claim 17, wherein the metasurface comprises nanostructures operable to interact with the light wave so as to change at least one of the amplitude or phase of the light wave.

26. The device according to claim 17, wherein the surface of the coating has a roughness less than a predetermined maximum roughness.

27. The device comprises a second coating on a second surface of the substrate, the second surface of the substrate being on the side opposite to the first surface of the substrate, and The surface of the second coating defines a second functional structure. The device according to claim 17.

28. The device according to claim 17, wherein the coating has a thickness greater than 10 microns.

29. A coating deposition apparatus, A stamp aligner, A controller communicatively coupled to the stamp aligner and the coating deposition device A system comprising: The system is configured to: Provide a coating on a first surface of a substrate and on a metasurface on the first surface of the substrate; Imprint the coating such that the surface of the coating has predetermined characteristics A system configured to perform operations including the above. **Claim 30** A light emitting device; A metasurface device A module comprising: The metasurface device includes: A substrate; A metasurface on a first surface of the substrate; A coating on the metasurface and on the first surface of the substrate, wherein the surface of the coating defines a functional structure; And comprising: The metasurface device is configured to interact with light generated by the light emitting device. **Claim 31** A light sensing device; A metasurface device A module comprising: The metasurface device includes: A substrate; A metasurface on a first surface of the substrate; A coating on the metasurface and on the first surface of the substrate, wherein the surface of the coating defines a functional structure; And comprising: The metasurface device is configured to interact with light incident on the module and transmit the modified light to the light sensing device.

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