Image sensors with height-varying metasurface for enhanced color performance

Abstract

An image sensor structure includes an optical-to-electrical conversion layer comprising a plurality of optical-to-electrical conversion elements; a substrate disposed on a surface of the optical-to-electrical conversion layer; and a metasurface disposed on a surface of the substrate opposite the optical-to-electrical conversion layer, the metasurface comprising a plurality of pillar structures extending away from the surface of the substrate along an axis, wherein a first pillar structure of the plurality of pillar structures has a different dimension than a second pillar structure of the plurality of pillar structures along the axis, and the plurality of pillar structures is configured to direct a plurality of colors of an incident light to corresponding ones of the plurality of optical-to-electrical conversion elements.

Description

Atty. Docket No. 4502-86801 (6000766PCT02)Image Sensors With Height-Varying Metasurface for Enhanced Color PerformanceCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 892,906 filed October 3, 2025, which is hereby incorporated by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure is generally related to semiconductor structures and electronics and, in particular embodiments, to image sensors for electronic devices.BACKGROUND

[0003] An image sensor is a device that captures light and converts the captured light into electrical signals to be used for forming an image or a video. A typical image sensor has an image sensing portion that includes a photosensitive area for collecting a charge in response to incident light. In an example, an image sensor may include light-sensitive pixels arranged in a uniform or regular pattern (e.g., in rows and columns). Each pixel may include a photosensor that produces an electrical signal corresponding to the intensity of light that falls on that pixel. Image sensors are widely used in various electronic devices, such as wearable devices, smartphones, medical imaging devices, digital cameras, automotive cameras, computer vision systems, etc.SUMMARY

[0004] The disclosed aspects / embodiments of the present disclosure provide systems and / or devices that include color image sensors that can produce color images with enhanced color fidelity. More specifically, a color image sensor may include a light router structure (referenced herein as a metasurface) with height-varying nanostructures (or pillar structures) to spatially direct different wavelength components (e.g., different color lights) of incident light to designated color sensing regions, thereby increasing the proportion of useful light reaching each color sensing region. The heights of the individual nanostructures may be configured to vary within a predetermined range to provide the desired color light routing paths. The height-varying nanostructures can provide superior manufacturability compared to metasurface color light routers with freeform geometries that are typical of inverse design outcomes. For instance, the disclosed height-varying nanostructures can be readily implemented using standard complementary metal oxideAtty. Docket No. 4502-86801 (6000766PCT02) semiconductor (CMOS) fabrication processes. Thus, the disclosed metasurface with heightvarying nanostructures can be integrated into CMOS image sensors without incurring significant additional manufacturing costs.

[0005] A first aspect of the embodiments of the present disclosure relates to an image sensor structure comprising an optical-to-electrical conversion layer comprising a plurality of optical-to- electrical conversion elements; a substrate disposed on a surface of the optical-to-electrical conversion layer; and a metasurface disposed on a surface of the substrate opposite the optical-to- electrical conversion layer, the metasurface comprising a plurality of pillar structures extending away from the surface of the substrate along an axis, wherein a first pillar structure of the plurality of pillar structures has a different dimension than a second pillar structure of the plurality of pillar structures along the axis, and the plurality of pillar structures is configured to direct a plurality of colors of an incident light to corresponding ones of the plurality of optical-to-electrical conversion elements.

[0006] Optionally, in any of the preceding aspects, another implementation of the aspect provides that a dimension of the first pillar structure along the axis is between 10 nanometers (nm) and 1600 nm.

[0007] Optionally, in any of the preceding aspects, another implementation of the aspect provides that at least one of a length or a width of the first pillar structure is between 100 nanometers (nm) and 1200 nm.

[0008] Optionally, in any of the preceding aspects, another implementation of the aspect provides that at least a third pillar structure and a fourth pillar structure of the plurality of pillar structures are spaced apart from each other by an air gap.

[0009] Optionally, in any of the preceding aspects, another implementation of the aspect provides that at least a fifth pillar structure and a sixth pillar structure of the plurality of pillar structures comprise a same cross-sectional shape along the axis.

[0010] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the plurality of pillar structures comprises at least one of titanium dioxide (TiO?), silicon nitride (SiNx), silicon (Si), or silicon dioxide (SiO2).

[0011] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the substrate comprises silicon.Atty. Docket No. 4502-86801 (6000766PCT02)

[0012] Optionally, in any of the preceding aspects, another implementation of the aspect provides that a subset of adjacent ones of the plurality of pillar structures corresponds to a single pixel element.

[0013] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the subset of adjacent ones of the plurality of pillar structures is configured to direct a first color of the plurality of colors of the incident light to a first optical-to-electrical conversion element of the plurality of optical-to-electrical conversion elements and a second color of the plurality of colors of the incident light to a second optical-to-electrical conversion element of the plurality of optical-to-electrical conversion elements, the first color is different than the second color, and the first optical-to-electrical conversion element is different than the second optical-to-electrical conversion element.

[0014] Optionally, in any of the preceding aspects, another implementation of the aspect provides that at least one of a width or a length of the single pixel element is between 0.2 micrometers (pm) and 20.6 pm.

[0015] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the image sensor structure further includes a color filtering layer disposed between the substrate and the optical-to-electrical conversion layer, the color filtering layer comprising a plurality of color filtering regions, wherein the plurality of pillar structures is further configured to direct a respective color of the plurality of colors of the incident light to a corresponding one of the plurality of color filtering regions that is configured to pass through light of the respective color.

[0016] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the plurality of color filtering regions comprises at least one of a green color filtering region, a blue color filtering region, or a red color filtering region.

[0017] Optionally, in any of the preceding aspects, another implementation of the aspect provides that at least one of the red color filtering region has a passband less than 100 nanometers (nm), the blue color filtering region has a passband less than lOOnm, or the green color filtering region has a passband less than 50 nm.

[0018] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the image sensor structure further includes a photo shielding element extending from the substrate towards and through at least a portion of the optical-to-electrical conversion layer andAtty. Docket No. 4502-86801 (6000766PCT02) separating a pair of adjacent optical-to-electrical conversion elements of the plurality of optical-to- electrical conversion elements.

[0019] Optionally, in any of the preceding aspects, another implementation of the aspect provides that a dimension of the photo shielding element along a second axis parallel to the surface of the substrate is between 90 nanometers (nm) and 1100 nm.

[0020] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the photo shielding element comprises a metal material.

[0021] A first aspect of the embodiments of the present disclosure relates to an electronic device comprising an image sensor comprising an array of pixel elements, each comprising an optical-to- electrical conversion layer comprising a plurality of optical-to-electrical conversion elements; and an optical signal routing layer adjacent to the optical-to-electrical conversion layer along an axis, the optical routing layer comprising a plurality of pillar structures extending along the axis and configured to direct a plurality of colors of an incident light to corresponding ones of the plurality of optical-to-electrical conversion elements, wherein at least a first pillar structure of the plurality of pillar structures has a different height than a second pillar structure of the plurality of pillar structures; and an electrical signal processing component coupled to the image sensor.

[0022] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the plurality of pillar structures comprises titanium dioxide (TiO2), silicon nitride (SiNx), silicon (Si), or silicon dioxide (SiO2).

[0023] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the electronic device further includes a color filtering layer disposed between the optical-to-electrical conversion layer and the optical signal routing layer, the color filtering layer comprising a plurality of color filtering regions, wherein the plurality of pillar structures is further configured to direct a respective color of the plurality of colors of the incident light to a corresponding one of the plurality of color filtering regions that is configured to pass through light of the respective color.

[0024] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the plurality of color filtering regions comprises at least one of a green color filtering region, a blue color filtering region, or a red color filtering region.Atty. Docket No. 4502-86801 (6000766PCT02)

[0025] Optionally, in any of the preceding aspects, another implementation of the aspect provides that at least two of the plurality of color fdtering regions passes through the same color light.

[0026] A third aspect of the embodiments of the present disclosure relates to a method of providing an image sensor, the method including providing an optical-to-electrical conversion layer, wherein the optical-to-electrical conversion layer comprises a plurality of optical-to-electrical conversion elements; and providing an optical signal routing layer on a surface of the optical-to- electrical conversion layer, wherein the optical signal routing layer comprises a plurality of pillar structures extending away from the surface of the optical-to-electrical conversion layer and configured to direct a plurality of colors of an incident light to corresponding ones of the plurality of optical-to-electrical conversion elements, and wherein at least a first pillar structure of the plurality of pillar structures has a different height than a second pillar structure of the plurality of pillar structures.

[0027] Optionally, in any of the preceding aspects, another implementation of the aspect provides that providing the optical signal routing layer comprises forming the plurality of pillar structures using a pattern transfer process.

[0028] Optionally, in any of the preceding aspects, another implementation of the aspect provides that providing the optical signal routing layer comprises determining heights of individual ones of the plurality of pillar structures based on an evaluation against a set of target routing paths to direct the plurality of colors of an incident light to corresponding ones of the plurality of optical- to-electrical conversion elements.

[0029] Optionally, in any of the preceding aspects, another implementation of the aspect provides that determining the heights of the individual ones of the plurality of pillar structures comprises varying a height of an individual one of the plurality of pillar structures within a predetermined range.

[0030] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the method further includes determining heights of individual ones of the plurality of pillar structures based on an artificial intelligence (Al)-based inverse design process.

[0031] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the method further includes providing a color filtering layer between the optical-to- electrical conversion layer and the optical signal routing layer, wherein the color filtering layerAtty. Docket No. 4502-86801 (6000766PCT02) comprises a plurality of color filtering regions, and the plurality of pillar structures is further configured to direct a respective color of the plurality of colors of the incident light to a corresponding one of the plurality of color filtering regions that is configured to pass through light of the respective color.

[0032] For the purpose of clarity, any one of the foregoing embodiments may be combined with any one or more of the other foregoing embodiments to create a new embodiment within the scope of the present disclosure.

[0033] These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0034] For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.

[0035] FIG. 1 illustrates a side cross-sectional view of a color image sensor structure with a height-varying metasurface according to an embodiment of the present disclosure.

[0036] FIG. 2A illustrates a perspective view of a color image sensor structure with a heightvarying metasurface according to an embodiment of the present disclosure.

[0037] FIG. 2B illustrates a top view of a pixel element in a color image sensor structure with a height-varying metasurface according to an embodiment of the present disclosure.

[0038] FIG. 2C illustrates a perspective view of a pixel element in a color image sensor structure with a height-varying metasurface according to an embodiment of the present disclosure.

[0039] FIG. 3 illustrates a side cross-sectional view of another color image sensor structure with a height-varying metasurface according to an embodiment of the present disclosure.

[0040] FIGS. 4A-4D illustrate a simulation of a color image sensor structure with a heightvarying metasurface according to an embodiment of the present disclosure.

[0041] FIG. 5A illustrates a chromaticity diagram with overlaid gamut triangles according to embodiments of the present disclosure.

[0042] FIG. 5B illustrates intensity curves of an image sensor with a height-varying metasurface according to embodiments of the present disclosure.Atty. Docket No. 4502-86801 (6000766PCT02)

[0043] FIG. 5C illustrates transmittance curves of color filters according to embodiments of the present disclosure.

[0044] FIG. 5D illustrates transmittance curves of an image sensor with a height-varying metasurface and color filters according to embodiments of the present disclosure.

[0045] FIG. 6 is a flowchart of an example method of providing a color image sensor structure with a height-varying metasurface according to an embodiment of the present disclosure.

[0046] FIG. 7 is a flowchart of an example method of determining heights for a height-varying metasurface in a color image sensor structure according to an embodiment of the present disclosure.

[0047] FIG. 8 is a block diagram of an electronic device including a color image sensor structure with a height-varying metasurface according to an embodiment of the present disclosure.

[0048] FIG. 9 is a block diagram of an example computer apparatus according to an embodiment of the present disclosure.DETAILED DESCRIPTION

[0049] It should be understood at the outset that although an illustrative implementation of one or more embodiments is provided below, the disclosed systems and / or methods may be implemented using any number of techniques, whether currently known or in existence. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.

[0050] The following terms are defined as follows unless used in a contrary context herein. Specifically, the following definitions are intended to provide additional clarity to the present disclosure. However, terms may be described differently in different contexts. Accordingly, the following definitions should be considered as a supplement and should not be considered to limit any other definitions of descriptions provided for such terms herein.

[0051] The digital image processing technology market is experiencing significant growth, driven by the increasing adoption of computer vision, artificial intelligence (Al), and machine learning across various industries (e.g., healthcare, security, manufacturing, retail, e-commerce, entertainment, education, etc.). As such, there is an increasing demand for high-resolution, high-Atty. Docket No. 4502-86801 (6000766PCT02) quality color imaging devices and / or systems. One type of image sensor that is commonly used in electronic devices is complementary metal oxide semiconductor (CMOS) image sensors. A CMOS image sensor may include an array of active pixel elements, each including a photodiode configured to convert incident electromagnetic radiation into a corresponding electrical signal, and a plurality of transistors operatively coupled to the photodiode for performing pixel-level operations including reset, amplification, and readout. Because CMOS image sensors lack the capability to differentiate among different wavelengths or frequencies (i.e., colors) of light, a color filter array (CFA) is commonly used in conjunction with a CMOS image sensor.

[0052] A CFA may include an array of color filters, each configured to selectively pass through narrow spectral bands of light corresponding to specific wavelengths (commonly red, green, or blue wavelengths) while attenuating or blocking other spectral components. For instance, the CFA may be placed before the pixel array (along a light propagation path) such that individual filters (of the CFA) are spatially aligned with corresponding photodiodes, allowing each pixel to capture light within a designated spectral or wavelength range. A widely adopted implementation of a CFA is the Bayer filter, which may include a checkerboard or mosaic arrangement of red, green, and blue filters, with green filters occupying approximately 50% of the array to account for the higher sensitivity of human vision to green wavelengths. One drawback with CFA-based color imaging is that the optical throughput may be limited, as each filter transmits only a fraction (typically less than one-third) of the incident light, resulting in significant energy loss or sensitivity. This may especially degrade the quality of images that are captured in dark or low-light environments. For example, the resulting images may have artifacts, such as loss of details, blotchy or blurry textures, etc. Moreover, spectral leakage and imperfect filter isolation can result in color crosstalk between adjacent pixels, thereby further degrading image fidelity and reducing the effective color gamut (e.g., the range of colors) available for accurate color reproduction.

[0053] While microlens may be integrated into CMOS image sensors to focus incoming light onto the active areas of the photodiodes within each pixel to maximize light capture, the optical throughput loss associated with CFAs persists. Various studies have been conducted to explore the use of a metasurface to overcome the optical efficiency limitations of CFA-based color imaging discussed above. For instance, one approach uses a freeform metasurface with structures having diverse, irregular shapes to split and focus visible light instead of filtering. However, integratedAtty. Docket No. 4502-86801 (6000766PCT02) circuit (IC) structures with freeform geometries can pose manufacturing challenges, for example, in terms of large-scale manufacturing and integration with standard CMOS fabrication processes.

[0054] Disclosed herein are techniques for providing color image sensors that can produce color images with enhanced color fidelity. More specifically, an image sensor may include a metasurface (e.g., a color light router) with height-varying nanostructures (or pillar structures), operating as a color light router to spatially direct different wavelength components (e.g., different color lights) of incident light to designated color sensing regions, thereby increasing the proportion of useful light reaching each color sensing region. The heights of the individual nanostructures are configured to vary within a certain range (e.g., between 10 nanometers (nm) and 1600 nm) to provide the desired color light routing paths. In an embodiment, the heights of individual nanostructures may be determined using inverse design techniques (e.g., based on machine learning or genetic algorithms). In an embodiment, the image sensor structure may further include a CFA. For instance, the height-varying metasurface may be disposed in front of the CFA along a light propagation path.

[0055] The disclosed height-varying nanostructure can be integrated into an image sensor to overcome the optical efficiency limitations of CFA-based color imaging. The disclosed heightvarying nanostructure can offer superior manufacturability compared to freeform metasurface color router. For instance, the disclosed height-varying nanostructures can be readily implemented using standard CMOS fabrication processes. Thus, the disclosed metasurface with height-varying nanostructures can be integrated into CMOS image sensors without incurring significant additional manufacturing costs.

[0056] FIG. 1 illustrates a side cross-sectional view of a color image sensor structure 100 with a height -varying metasurface 102 according to an embodiment of the present disclosure. The side cross-sectional view is in a y-z plane along line A-A of FIG. 2A. In an embodiment, the color image sensor structure 100 (e.g., an IC structure) is part of an electronic device (e.g., as shown in FIG. 8). At a high level, the color image sensor structure 100 may capture incident light 101 (e.g., reflected off an object or a scene) and convert the captured light into electrical signals for forming a digital color image. As shown in FIG. 1, the color image sensor structure 100 may include the metasurface 102, a substrate layer 104, and an optical -to-electrical conversion layer 106. The substrate layer 104 may be disposed between the metasurface 102 and the optical-to-electrical conversion layer 106. Stated differently, the substrate layer 104 may be disposed on a surface 120Atty. Docket No. 4502-86801 (6000766PCT02) of the optical-to-electrical conversion layer 106. The metasurface 102 may be disposed on a surface 122 of the substrate layer 104 opposite the optical-to-electrical conversion layer 106.

[0057] The substrate layer 104 may include substrate 112, for example, comprising silicon. The substrate 112 may function as a support structure for the metasurface 102. The optical-to- electrical conversion layer 106 may include a plurality of optical-to-electrical conversion elements 114, each configured to convert light (photons) into an electrical signal. The optical-to-electrical conversion elements 114 may be spaced apart from each other by isolation material 116, for example, comprising silicon dioxide (SiCh). The isolation material 116 may mitigate crosstalk between neighboring optical-to-electrical conversion elements 114. In an example, the optical-to- electrical conversion elements 114 may be photodiodes formed of silicon, where each photodiode may include a semiconductor junction configured to convert light (photons) into an electrical signal.

[0058] The metasurface 102 may include a plurality of pillar structures 110 (e.g., having columnar shapes). The pillar structures 110 may extend away from the surface 122 of the substrate layer 104 along the z-axis. The pillar structures 110 may have varying dimensions (e.g., heights 103) along the z-axis. As illustrated in the example of FIG. 1, the pillar structure 110a may have a height 103a and the pillar structure 110b may have a height 103b different than the height 103a. For simplicity, FIG. 1 only illustrates the heights 103a and 103b respectively for the pillar structures 110a and 110b. In an embodiment, each of the pillar structure 110 may have a height 103 (e.g., a dimension along the z-axis) between 10 nm and 1600 nm. In an embodiment, each of the pillar structure 110 may have a height 103 between 600 nm and 1500 nm. In an embodiment, the pillar structures 110 may have the same dimension 105 (e.g., a width or a length) along the y-axis. In other embodiments, two or more of the pillar structures 110 may have different dimensions 105. For simplicity, FIG. 1 only illustrates the dimension 105 for the pillar structure l lOd. In an embodiment, the dimension 105 may be greater than 100 nm (e.g., to ease manufacturability). In an embodiment, the dimension 105 may be between 100 nm and 150 nm. In an embodiment, the dimension 105 may be between 100 nm and 1200 nm. In some instances, the pillar structures 110 may be referred to as nanostructures. The pillar structures 110 may include a semiconductor material, for example, including, but not limited to, titanium oxide (TiO?), silicon nitride (SiNx), silicon (Si), and / or silicon dioxide (SiCh). In a certain embodiment, the pillar structures 110 may include TiO2. In some embodiments, two or more of the pillar structures 110Atty. Docket No. 4502-86801 (6000766PCT02) may include materials of different refractive indices. In an example, the pillar structures 110 may include one or more pillar structures 110 made of TiCE and one or more pillar structures 110 made of SiNx on the same substrate 112. In some embodiments, all of the pillar structures 110 may include the same material of the same refractive index (e.g., TiCE).

[0059] In some embodiments, the pillar structures 110 may be arranged next to one another with no gap between adjacent pillar structures 110 (e.g., the pillar structures 110a and 110c). In some embodiments, the pillar structures 110 may be arranged such that at least one pair of adjacent pillar structures 110 may be spaced apart from each other by a gap (e.g., an air gap). As an example, the pillar structure 110a and the adjacent pillar structure 110b are separated by a gap 107. In an embodiment, the gap 107 may be between 100 nm and 120 nm (e.g., corresponding to the dimension 105 of an individual pillar structure 110). Generally, the pillar structures 110 may be spaced apart from each other, in contact with each other (i.e., no gap), or a combination thereof. In an embodiment, the pillar structures 110 may be arranged according to a matrix grid layout (e.g., with matrix elements arranged in rows along the y-axis and columns along the x-axis), where one or more of the matrix elements may be an air gap without a pillar structure 110.

[0060] The pillar structures 110 may be configured to direct a plurality of colors of the incident light 101 to corresponding ones of the plurality of optical-to-electrical conversion elements 114. The heights of the pillar structures 110 and / or the arrangement (the locations) of the pillar structures 110 in the metasurface 102 may be configured to bend, focus, or redirect different wavelengths (or colors) of light in different directions as will be discussed more fully below with reference to FIGS. 2A-2C, 3, 4A-4D, 5A-5D, and 6. For instance, the one or more of the pillar structures 110 may direct a particular color light to one or more designated optical-to-electrical conversion elements 114 as will be discussed more fully below with reference to FIGS. 2A-2C. In some instances, the metasurface 102 may also be referred to as an optical signal router or a color light router.

[0061] FIG. 2A illustrates a perspective view of the color image sensor structure 100 of FIG. 1 according to an embodiment of the present disclosure. As shown in FIG. 2A, the color image sensor structure 100 may include a plurality of pixel elements 202 (which may also be referred to as color pixel elements). For simplicity, FIG. 2A only illustrates one pixel element with the label 202. Each pixel element 202 may correspond to a pixel of an image output by the color image sensor structure 100. The color image sensor structure 100 may generally include any suitableAtty. Docket No. 4502-86801 (6000766PCT02) number of pixel elements 202 in the color image sensor structure 100. The resolution of an output image may be dependent on the number of pixel elements 202 in the color image sensor structure 100. In an embodiment, each pixel element 202 may have a width 206 (e.g., a dimension along the x-axis) between 0.4 micrometers (pm) and 0.6 pm and a length 207 (e.g., a dimension along the y- axis) between 0.4 pm and 0.6 pm. In an embodiment, each pixel element 202 may have a width 206 between 0.2 pm and 20.6 pm. In an embodiment, each pixel element 202 may have a length 207 between 0.2 pm and 20.6 pm. In an embodiment, the width 206 and the length 207 of an individual pixel element 202 may be about the same. In other embodiments, the width 206 and the length 207 of an individual pixel element 202 may be different.

[0062] FIG. 2B illustrates a top view of an individual pixel element 202 in an x-y view according to an embodiment of the present disclosure. As shown in FIG. 2B, the pixel element 202 may be divided into four sub-pixel elements 204 (individually shown as 204a, 204b, 204c, and 204d) to provide color sensing. For instance, each of the sub-pixel element 204 may be configured to sense a particular color light (e.g., red, green, or blue light). In an embodiment, each pixel element 204 may include one sub-pixel element 204 configured to sense red light, two sub-pixel elements 204 configured to sense green light, and one sub-pixel element 204 configured to sense blue light. As an example, the sub-pixel element 204c may be configured to sense red light, the sub-pixel element 204b may be configured to sense blue light, the sub-pixel elements 204a and 204d may be configured to sense green light. Such an arrangement may be referred to as an RGGB form or color pattern (e.g., based on Bayer color filtering). Generally, the sub-pixel elements 204a-204d may be configured alternatively to sense red, green, blue lights.

[0063] FIG. 2C illustrates a perspective of an individual pixel element 202 according to an embodiment of the present disclosure. For simplicity, in FIG. 2C, the substrate layer 102 is shown by the empty-filled box and the isolation material 116 between the optical-to-electrical conversion elements 114 is not shown. As shown in FIG. 2C, an individual pixel element 202 may include a metasurface 102, a substrate layer 104, and an optical-to-electrical conversion layer 106 as discussed above with reference to FIG. 1. For instance, the metasurface 102 may include height-varying pillar structures 110. Further, in an embodiment, the individual pillar structures 110 may have the same dimension 209 (e.g., a width or a length) along the x-axis. In other embodiments, two or more of the pillar structures 110 may have different dimensions 209 along the x-axis. For simplicity, FIG. 2C only illustrates the dimension 209 for the pillar structure HOe. In an embodiment, theAtty. Docket No. 4502-86801 (6000766PCT02) dimension 209 may be greater than 100 nm (e.g., to ease manufacturability). In an embodiment, the dimension 209 may be between 100 nm and 150 nm. In an embodiment, the dimension 209 may be between 100 nm and 1200 nm. In an embodiment, the individual pillar structures 110 may have substantially regular and uniform cross-sectional shapes (e.g., square or rectangular shapes as shown in FIG. 2C) along the z-axis. In an embodiment, the individual pillar structures 110 may have substantially regular and uniform cross-sectional shapes and sizes along the z-axis. Generally, the individual pillar structures 110 may have any suitable cross-sectional shapes and / or sizes (e.g., that ease manufacturability).

[0064] As further shown FIG. 2C, the pixel element 202 may include four optical-to-electrical conversion elements 114 (individually shown as 114a, 114b, 114c, and 114d). Each optical-to- electrical conversion element 114 may correspond to one sub-pixel element 204. Statedly differently, each sub-pixel element 204 may be spatially aligned to a corresponding one of the optical-to- electrical conversion elements 114. For instance, the sub-pixel element 204a may correspond to and spatially aligned to the optical-to-electrical conversion element 114a, the sub-pixel element 204b may correspond to and spatially aligned to the optical-to-electrical conversion element 114b, the subpixel element 204c may correspond to and spatially aligned to the optical-to-electrical conversion element 114c, and the sub-pixel element 204d may correspond to and spatially aligned to the optical- to-electrical conversion element 114d.

[0065] In an embodiment, the pillar structures 110 in the metasurface 102 may be configured to direct (or route) different wavelengths (or colors, e.g., red, blue, and green) of the incident light 101 to corresponding ones of the optical-to-electrical conversion elements 114 by varying the heights 103 of the pillar structures 110. Referring to the RGGB example discussed above with reference to FIG. 2B, the pillar structures 110 may be configured to direct red light 210 (shown by the solid arrows) to the optical-to-electrical conversion element 114c, green light 212 (shown by the dotted arrows) to the optical-to-electrical conversion elements 114a and 114d, and the blue light 214 (shown by the dashed arrows) to the optical-to-electrical conversion element 114b. In some embodiments, the pillar structures 110 may have substantially the same cross-sectional shapes (e g., square or rectangular shapes as shown in FIG. 2C) about perpendicular to the heights 103 and may rely on the varying heights 103 to provide the desired color light routing.

[0066] Stated differently, the color image sensor structure 100 includes an optical-to-electrical conversion layer 106 including a plurality of optical-to-electrical conversion elements 114, an opticalAtty. Docket No. 4502-86801 (6000766PCT02) signal routing layer (e.g., the metasurface 102) adjacent to the optical-to-electrical conversion layer 106 along an axis (e.g., the z-axis). The optical routing layer includes a plurality of pillar structures 110 extending along the axis and configured to direct a plurality of colors of an incident light 101 to corresponding ones of the plurality of optical-to-electrical conversion elements 114. The plurality of pillar structures 110 have varying heights 103. For instance, at least a first pillar structure 110 (e.g., the pillar structure 110a shown in FIG. 1 ) of the plurality of pillar structures 110 has a different height103 than a second pillar structure 110 (e.g., the pillar structure 110b shown in FIG. 1) of the plurality of pillar structures 110. Further, at least a subset of the plurality of pillar structures 110 corresponds to a single pixel element 202 (e.g., as shown in FIG. 2C). The subset of the plurality of pillar structures 110 is configured to direct a first color of the plurality of colors of the incident light 101 to a first optical-to-electrical conversion element 114 of the plurality of optical-to-electrical conversion elements 114 and a second color of the plurality of colors of the incident light 101 to a second optical-to-electrical conversion element 114 of the plurality of optical-to-electrical conversion elements 114. The first color is different than the second color and the first optical-to- electrical conversion element 114 is different than the second optical-to-electrical conversion element 114 (e.g., as shown in FIG. 2C). For instance, the first color of the incident light 101 may be one of red light 210, green light 212, or blue light 214, and the second color of the incident light101 may be another one of the red light 210, the green light 212, or the blue light 214.

[0067] FIG. 3 illustrates a side cross-sectional view of another color image sensor structure 300 with a height-varying metasurface according to an embodiment of the present disclosure. The color image sensor structure 300 may be substantially similar to the color image sensor structure 100. However, the color image sensor structure 300 may further include a color fdt ering layer 302 to further enhance color quality of output images. The side cross-sectional view in FIG. 3 is in a y-z plane similar to the side cross-sectional view of FIG. 1. Further, FIG. 3 may use the same reference numerals to refer to the same layers and / or elements as in FIG. 1 and FIGS. 2A-2C.

[0068] As shown in FIG. 3, the color image sensor structure 300 may include a metasurface102 (including a plurality of pillar structures 110 with varying heights), an optical-to-electrical conversion layer 106, and a substrate layer 104 between the metasurface 102 and the optical-to- electrical conversion layer 106 as discussed above with reference to FIG. 1. The color image sensor structure 300 may further include a color filtering layer 302 disposed between the substrate layer104 and the optical-to-electrical conversion layer 106. The color filtering layer 302 may include aAtty. Docket No. 4502-86801 (6000766PCT02) plurality of color filtering regions 304 (e g., color filters). For instance, the plurality of color filtering regions 304 may include at least one of a green color filtering region 304, a blue color filtering region 304, or a red color filtering region 304. A red color filtering region 304 may pass through red light (e.g., the red light 210) and block or at least attenuate remaining color lights or wavelength components (e.g., the green light 212 and the blue light 214). Agreen color filtering region 304 may pass through green light (e.g., the green light 212) and block or at least attenuate remaining color lights or wavelength components (e.g., the red light 210 and the blue light 214). A blue color filtering region 304 may pass through blue light (e.g., the blue light 212) and block or at least attenuate remaining color lights or wavelength components (e.g., the green light 212 and the red light 210). Generally, red light may have wavelengths between 620 nm and 750 nm, green light may have wavelengths between 495 nm and 570 nm, and blue light may have wavelengths between 380 nm and 500 nm.

[0069] Each color filtering regions 304 may be spatially aligned to one of the optical-to- electrical conversion elements 114. The plurality of pillar structures 110 may be further configured to direct a respective color of the plurality of colors of the incident light 101 to a corresponding one of the plurality of color filtering regions 304 that is configured to pass through light of the respective color. That is, the plurality of pillar structures 110 may be configured to direct red color light of the incident light 101 to a red color filtering region 304, green color light of the incident light 101 to a green color filtering region 304, and blue color light of the incident light 101 to a blue color filtering region 304.

[0070] In an embodiment, the red color filtering region 304 may have a passband (e.g., a fullwidth at half-maximum (FWHM) passband) less than 100 nm, the green color filtering region 304 may have a passband less than 50 nm, and the blue color filtering region 304 may have a passband less than 100 nm, for example, to provide better color separation. In an embodiment, to reduce crosstalk between adjacent color filtering regions 304, the color image sensor structure 300 may further include photo shielding elements 310. For instance, each photo shielding element 310 may be disposed between a corresponding pair of adjacent color filtering regions 304 (e g., between a red color filtering region 304 and a green color filtering region 304, between a red color filtering region 304 and a blue color filtering region 304, between a blue color filtering region 304 and a green color filtering region 304). In an embodiment, the photo shielding elements 310 may extend from the substrate 112 through the color filtering layer 302, towards and through at least a portion of theAtty. Docket No. 4502-86801 (6000766PCT02) optical-to-electrical conversion layer 106. Because the color filtering regions 304 are spatially aligned to corresponding ones of the optical-to-electrical conversion elements 114, the photo shielding element 310 may also be extended to separate adjacent optical-to-electrical conversion elements 114. That is, the photo shielding elements 310 may also mitigate crosstalk between adjacent optical-to-electrical conversion elements 114, thereby further improving image quality (sensitivity). In an embodiment, a dimension 305 of an individual photo shielding element 310 along an axis (e.g., the y-axis) parallel to a surface 120 of the substrate layer 104 may be between 90 nm and 1100 nm. In an embodiment, the photo shielding element 310 may include a metal material. In an embodiment, a dimension 307 of an individual photo shielding element 310 along an axis (e.g., the z-axis) about perpendicular to a surface 120 of the substrate layer 104 may be between 0.8 pm and 3 pm. In an embodiment, the dimension 307 may be between 1 pm and 2 pm.

[0071] In some embodiments, the photo shielding elements 310 may also be used in the color image sensor structure 100 of FIG. 1 without a color filtering layer 302 to provide similar crosstalk mitigation functionalities. For instance, in the color image sensor structure 100, each of the photo shielding elements 310 may be disposed between a corresponding pair of adjacent optical-to- electrical conversion elements 114, extending from the substrate 112 towards and through at least a portion of the optical-to-electrical conversion layer 106.

[0072] FIGS. 4A-4D illustrate a simulation of a color image sensor structure 400 with a heightvarying metasurface 402 according to an embodiment of the present disclosure. In FIGS. 4A-4D, each of the y-axis and z-axis may represent respective physical dimensions of the color image sensor structure 400 in some constant units. The color image sensor structure 400 may be substantially similar to the color image sensor structures 100 and 300.

[0073] FIG. 4A illustrates a side cross-sectional view (e.g., in a y-z plane) of a configuration of the color image sensor structure 400 in the simulation. As shown, the color image sensor structure 400 may include the metasurface 402, a substrate layer 404, a color filtering layer 406, and an optical-to-electrical conversion layer 408. The metasurface 402, the substrate layer 404, the color filtering layer 406, and the optical-to-electrical conversion layer 408 may respectively correspond to the metasurface 102, the substrate layer 104, the color filtering layer 302, and the optical-to-electrical conversion layer 106 discussed above with reference to FIGS. 1, 2A-2C, and 3. For instance, the metasurface 402 may include height-varying pillar structures 410 corresponding to the pillar structure 110 discussed above. Further, the color filtering layer 406Atty. Docket No. 4502-86801 (6000766PCT02) may include a blue color filter (show by “B”), a green color filter (shown by “G”), and a red filter (shown by “R”), each corresponding to a color filtering region 304 discussed above. The region of each color filter may correspond to a sub-pixel 420 (e.g., the sub-pixel 204 discussed above with reference to FIGS. 2B-2C). The sub-pixel 420 are individual shown as 420a, 420b, and 420c.

[0074] FIG. 4B illustrates light propagations through the color image sensor structure 400 for an incident light with a wavelength of 0.45 pm (corresponding to blue light). As shown by the density of the dotting lines in FIG. 4B, a major portion (e.g., greater than 90 %) of the blue light is directed (or routed) to the blue color filter (“B”) located at the sub-pixel 420a.

[0075] FIG. 4C illustrates light propagations through the color image sensor structure 400 for an incident light with a wavelength of 0.55 pm (corresponding to green light). Similarly, as shown by the density of the dotted lines in FIG. 4C, a major portion (e.g., greater than 90 %) of the green light is directed (or routed) to the green color filter (“G”) located at the sub-pixel 420b.

[0076] FIG. 4D illustrates light propagations through the color image sensor structure 400 for an incident light with a wavelength of 0.65 pm (corresponding to red light). Similarly, as shown by the density of the dotted lines in FIG. 4D, a major portion (e.g., greater than 90 %) of the red light is directed (or routed) to the red color filter (“R”) in the sub-pixel 420c.

[0077] FIG. 5A illustrates a chromaticity diagram 500 with overlaid gamut triangles 502, 504, and 506 according to embodiments of the present disclosure. In FIG. 5A, the horizontal axis may represent commission international on illumination standard (CIE) x in some constant units, and the vertical axis may represent CIE y in some constant units. The gamut triangle 502 may represent the color range output by a first color image sensor structure including a height-varying metasurface (e.g., the height-varying metasurface 102) without a CFA (e.g., similar to the color image sensor structure 100 discussed herein). The gamut triangle 504 may represent the color range output by a second color image sensor structure including a CFA without a height- varying metasurface (e.g., the height-varying metasurface 102). The gamut triangle 506 may represent the color range output by a third color image sensor structure including a height-varying metasurface (e g., the height-varying metasurface 102) and a CFA (e.g., similar to the color image sensor structure 300 discussed herein). As can be seen, the color image sensor structure including the height -varying metasurface and the CFA may provide the largest color dynamic range as shown by the gamut triangle 506 having the largest area among the gamut triangles 502, 504, and 506.Atty. Docket No. 4502-86801 (6000766PCT02)

[0078] FIG. 5B illustrates intensity curves 512, 514, and 516 provided by a color image sensor structure (e.g., the first color image sensor structure discussed above with reference to FIG. 5A) with the height-varying metasurface according to embodiments of the present disclosure. In FIG. 5B, the horizonal axis may represent space in some constant units and the vertical axis may represent intensity in some constant units. The intensity curve 512 illustrates the intensity for blue light (e.g., the blue light 214). The intensity curve 514 illustrates the intensity for green light (e.g., the green light 212). The intensity curve 516 illustrates the intensity for red light (e.g., the blue light 210). In an embodiment, the gamut triangle 502 may correspond to the intensity curves 512, 514, and 516.

[0079] FIG. 5C illustrates transmittance curves 522, 524, and 526 of blue, green, and red color fdters, respectively, according to embodiments of the present disclosure. In FIG. 5C, the horizonal axis may represent wavelengths in nm and the vertical axis may represent transmittance in some constant units. In an example, the blue, green, and red color fdters may correspond to the color fdters in the second color image sensor structure discussed with reference to FIG. 5A.

[0080] FIG. 5D illustrates transmittance curves 532, 534, and 536 provided by a color image sensor structure (e.g., the third color image sensor structure discussed above with reference to FIG. 5A) with a height-varying metasurface (e.g., the height-varying metasurface 102) and a CFA according to embodiments of the present disclosure. In FIG. 5D, the horizonal axis may represent wavelengths in nm and the vertical axis may represent transmittance in some constant units. The transmittance curve 532 illustrates the transmittance for blue light (e.g., the blue light 214). The transmittance curve 534 illustrates the transmittance for green light (e.g., the green light 212). The transmittance curve 536 illustrates the transmittance for red light (e.g., the blue light 210). As can be seen in FIG. 5D, the transmittance curve 532 for blue light may have a peak efficiency of about 0.74, the transmittance curve 534 for green light may have a peak efficiency of about 0.72, the transmittance curve 536 for red light may have a peak efficiency of about 0.89. Thus, an optical efficiency of such a color image structure (including a height-varying metasurface for color routing and a CFA) may be about 79 %.

[0081] FIG. 6 is a flowchart of an example method 600 of providing a color image sensor structure with a height -varying metasurface according to an embodiment of the present disclosure. The color image sensor structure may be similar to color image sensor structures 100 or 300, and the height-varying metasuface may be similar to the metasurface 102 discussed above. AsAtty. Docket No. 4502-86801 (6000766PCT02) illustrated, FIG. 6 includes a number of enumerated operations, but embodiments of the operations in FIG. 6 may include additional operations before, after, and in between the enumerated operations. In some embodiments, one or more of the enumerated operations may be omitted or performed in a different order.

[0082] At operation 602, an optical-to-electrical conversion layer (e.g., the optical-to-electrical conversion layer 106) is provided. The optical-to-electrical conversion layer may include a plurality of optical-to-electrical conversion elements (e.g., the optical-to-electrical conversion elements 114). Generally, the optical-to-electrical conversion layer may be provided using any suitable semiconductor processes (e.g., ions implant, doping, photolithography, etc.).

[0083] At operation 604, an optical signal routing layer (e.g., the metasurface 102) is provided on a surface of the optical-to-electrical conversion layer. The optical signal routing layer includes a plurality of pillar structures (e.g., the pillar structures 110) extending away from the surface of the optical-to-electrical conversion layer and configured to direct a plurality of colors of an incident light (e.g., the light 101) to corresponding ones of the plurality of optical-to-electrical conversion elements, where at least a first pillar structure of the plurality of pillar structures has a different height (e.g., the heights 103) than a second pillar structure of the plurality of pillar structures. In an embodiment, providing the optical signal routing layer includes forming the plurality of pillar structures using a pattern transfer process (e.g., a molding process, a nano-patterning process). In an embodiment, providing the optical signal routing layer includes determining heights of the plurality of pillar structures based on an evaluation against a set of target routing paths to direct the plurality of colors of an incident light to corresponding ones of the plurality of optical-to-electrical conversion elements. In an embodiment, determining the heights of the plurality of pillar structures includes varying the heights of one or more individual ones of the plurality of pillar structures within a predetermined range (e.g., between 10 nm and 1600 nm). In an embodiment, determining the heights of the plurality of pillar structures further varying the heights of one or more individual ones of the plurality of pillar structures within a predetermined range (e.g., between 10 nm and 1600 nm) while maintaining a regular cross-sectional shape (e.g., square or rectangular shape) for individual ones of the plurality of pillar structures about perpendicular to the heights. In an embodiment, providing the optical signal routing layer includes determining heights of the plurality of pillar structures based on an inverse model technique. An example of height determination is discussed below with reference to FIG. 7Atty. Docket No. 4502-86801 (6000766PCT02)

[0084] In an embodiment, the method 600 further includes providing a color fdtering layer (e.g., the color fdtering layer 302) between the optical-to-electrical conversion layer and the optical signal routing layer. The color fdtering layer includes a plurality of color fdtering regions (e.g., the color fdtering regions 304). Further, the plurality of pillar structures is configured to direct a respective color of the plurality of colors of the incident light to a corresponding one of the plurality of color fdtering regions that is configured to pass through light of the respective color. Generally, the color fdtering layer may be provided using any suitable semiconductor processes (e.g., spin coating, etching, photolithography, etc.).

[0085] FIG. 7 is a flowchart of an example method 700 of determining heights for a heightvarying metasurface (e.g., the metasurface 102) in a color image sensor structure (e.g., the color image sensor structures 100 and 300) according to an embodiment of the present disclosure. In an embodiment, the method 700 may be used in conjunction with the method 600. For instance, the method 700 may be implemented as part of operation 602.

[0086] As shown in FIG. 7, at operation 702, the heights (e.g., the heights 103, a dimension along the z-axis in FIGS. 1 and 3) for a plurality of pillar structures (e.g., the pillar structures 110) in a color image sensor structure (e.g., the color image sensor structures 100 and 300) are initialized. In an example, the heights may be initialized to arbitrary values within a predetermined range (e.g., between 2 nm and 1600 nm). In an example, the widths (e.g., the dimension 209 along the x-axis) and the lengths (e.g., the dimension 105 along the y-axis) of the pillar structures may also be initialized to predetermined values. In an example, the cross-sectional shapes of the pillar structures along the heights may also be initialized to predetermined shape (e.g., a regular shape, a square, a rectangular shape, etc.)

[0087] At operation 704, an evaluation of color routing provided by the pillar structure is performed against an objective function associated with a set of target optical routing paths. For instance, the target optical routing paths may be similar to the paths for the red light 210, the green light 212, and the blue light 214 discussed above with reference to FIG. 2C. That is, the target optical routing paths may include a set of optical paths for routing red light to designated regions (e.g., designated optical-to-electrical conversion elements 114 and / or color filtering region 304) of the color image sensor structure for red color light sensing, a set of optical paths for routing green light to designated regions of the color image sensor structure for green color light sensing, and a set of optical paths for routing blue light to designated regions of the color image sensor structureAtty. Docket No. 4502-86801 (6000766PCT02) for blue color light sensing. At operation 706, the heights of the pillar structures are adapted based on the evaluation at operation 704. For instance, the evaluation may output an error measure and the adaptation may include adjusting the heights for one or more of the pillar structures to minimize the error. In an embodiment, the adaptation may include varying the heights of individual ones of the plurality of pillar structures within a predetermined range (e.g., between 10 nm and 1600 nm). In an embodiment, the adaptation may include varying the heights of individual ones of the plurality of pillar structures within a predetermined range (e.g., between 10 nm and 1600 nm) while maintaining a regular cross-sectional shape (e.g., square or rectangular shape) for individual ones of the plurality of pillar structures about perpendicular to the heights.

[0088] At operation 708, after the adaptation, a check for convergence is made. For instance, another evaluation similar to the evaluation at operation 704 may be performed to determine whether an error measure (between the color routing provided by the pillar structures and the set of target optical routing paths) satisfies a certain threshold. If not, the method 700 may proceed to 702 to repeat the determination process. Otherwise, the method 700 may proceed to operation 710 to generate an output indicating the respective heights determined for the pillar structures. In an embodiment, the method 700 may be referred to as an inverse design process or inverse modeling process. In some embodiments, the method 700 may leverage machine learning or Al tools or processes (e.g., genetic algorithm or gradient-based machine learning process). A genetic algorithm is a computational technique that mimics natural selection to find optimal solutions to complex problems. It uses genetic operators, such as selection, crossover, and mutation, to evolve a population of candidate solutions over multiple generations. As an example, the initialization at operation 702 may include initializing a genetic model, and the adaptation at operation 706 may include applying selection, cross-over, and / or mutation operations to update the genetic model.

[0089] FIG. 8 is a block diagram of an electronic device 800 including a color image sensor 804 with a height-varying metasurface according to an embodiment of the present disclosure. In an embodiment, the color image sensor 804 may correspond to the color image sensor structure 100 of FIG. 1 with the height-varying metasurface 102 (e.g., including the height-varying pillar structures 110). In another embodiment, the color image sensor 804 may correspond to the color image sensor structure 300 of FIG. 3 with the height-varying metasurface 102 and the color filtering layer 302.Atty. Docket No. 4502-86801 (6000766PCT02)

[0090] As shown, the electronic device 800 may include a lens module 802, the color image sensor 804, and an electrical signal processing module 806. The lens module 802 may be configured to converge or focus optical signals reflected by an external object towards the color image sensor 804. The color image sensor 804 may be configured to convert optical signals into analog electrical signals as discussed above. The electrical signal processing module 806 may be configured to construct an image based on the electrical signals received from the color image sensor 804. In some embodiments, the electrical signal processing module 806 may include analog-to-digital (A / D) converter(s) to convert the analog electrical signals into digital electrical signal. The electrical signal processing module 806 may further include a digital signal processor (DSP) to apply a series of mathematical algorithm operations to generate the output image.

[0091] FIG. 9 is a schematic diagram of an apparatus 900 (e.g., a network apparatus, a network node, a network router, a router, etc.). The apparatus 900 is suitable for implementing the disclosed embodiments as described herein. The apparatus 900 comprises ingress ports / ingress means 910 (a.k.a., upstream ports) and receiver units (Rx)Zreceiving means 920 for receiving data; a processor, logic unit, or central processing unit (CPU)Zprocessing means 930 to process the data; transmitter units (Tx) / transmitting means 940 and egress ports / egress means 950 (a.k.a., downstream ports) for transmitting the data; and a memory / memory means 960 for storing the data. In an embodiment, the receiver units (Rx) / receiving means 920 comprise a discrete circuit, integrated circuit, chip set, package, hardware module, electronic device, or other structure capable of receiving signals. In an embodiment, the transmitter units (Tx) / transmitting means 940 comprise a discrete circuit, integrated circuit, chip set, package, hardware module, electronic device, or other structure capable of transmitting signals. The apparatus 900 may also comprise optical-to-electrical (OE) components and electrical-to-optical (EO) components coupled to the ingress ports / ingress means 910, the receiver units / receiving means 920, the transmitter units / transmitting means 940, and the egress ports / egress means 950 for egress or ingress of optical or electrical signals.

[0092] The processor / processing means 930 is implemented by hardware and software. The processor / processing means 930 may be implemented as one or more CPU chips, cores (e.g., as a multi-core processor), field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), and digital signal processors (DSPs). The processor / processing means 930 is in communication with the ingress ports / ingress means 910, receiver units / receiving means 920, transmitter units / transmitting means 940, egress ports / egress means 950, and memory / memoryAtty. Docket No. 4502-86801 (6000766PCT02) means 960. The processor / processing means 930 comprises a metasurface height determination module 970. The metasurface height determination module 970 is able to implement the method 700 disclosed herein. The inclusion of the metasurface height determination module 970 therefore provides a substantial improvement to the functionality of the apparatus 900 and effects a transformation of the apparatus 900 to a different state. Alternatively, the metasurface height determination module 970 is implemented as instructions stored in the memory / memory means 960 and executed by the processor / processing means 930.

[0093] The apparatus 900 may also include input and / or output (I / O) devices or I / O means 980 for communicating data to and from a user. The I / O devices or I / O means 980 may include output devices such as a display for displaying video data, speakers for outputting audio data, etc. The I / O devices or I / O means 980 may also include input devices, such as a keyboard, mouse, trackball, etc., and / or corresponding interfaces for interacting with such output devices.

[0094] The memory / memory means 960 comprises one or more disks, tape drives, and solid- state drives and may be used as an over-flow data storage device, to store programs when such programs are selected for execution, and to store instructions and data that are read during program execution. The memory / memory means 960 may be volatile and / or non-volatile and may be readonly memory (ROM), random access memory (RAM), ternary content-addressable memory (TCAM), and / or static random-access memory (SRAM).

[0095] It should also be understood that the steps of the exemplary methods set forth herein are not necessarily required to be performed in the order described, and the order of the steps of such methods should be understood to be merely exemplary. Likewise, additional steps may be included in such methods, and certain steps may be omitted or combined, in methods consistent with various embodiments of the present disclosure.

[0096] While several embodiments have been provided in the present disclosure, it should be understood that the disclosed systems and methods might be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented.

[0097] In addition, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems,Atty. Docket No. 4502-86801 (6000766PCT02) modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled or directly coupled or communicating with each other may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the spirit and scope disclosed herein.

Claims

Atty. Docket No. 4502-86801 (6000766PCT02)CLAIMSWhat is claimed is:

1. An image sensor structure comprising: an optical-to-electrical conversion layer comprising a plurality of optical-to-electrical conversion elements; a substrate disposed on a surface of the optical-to-electrical conversion layer; and a metasurface disposed on a surface of the substrate opposite the optical-to-electrical conversion layer, the metasurface comprising a plurality of pillar structures extending away from the surface of the substrate along an axis, wherein: a first pillar structure of the plurality of pillar structures has a different dimension than a second pillar structure of the plurality of pillar structures along the axis, and the plurality of pillar structures is configured to direct a plurality of colors of an incident light to corresponding ones of the plurality of optical-to-electrical conversion elements.

2. The image sensor structure of claim 1, wherein a dimension of the first pillar structure along the axis is between 10 nanometers (nm) and 1600 nm.

3. The image sensor structure of any of claims 1-2, wherein at least one of a length or a width of the first pillar structure is between 100 nanometers (nm) and 1200 nm.

4. The image sensor structure of any of claims 1-3, wherein at least a third pillar structure and a fourth pillar structure of the plurality of pillar structures are spaced apart from each other by an air gap-5. The image sensor structure of claim 4, wherein at least a fifth pillar structure and a sixth pillar structure of the plurality of pillar structures comprise the same cross-sectional shape along the axis.Atty. Docket No. 4502-86801 (6000766PCT02)6. The image sensor structure of any of claims 1-5, wherein the plurality of pillar structures comprises at least one of titanium dioxide (TiCh), silicon nitride (SiNx), silicon (Si), or silicon dioxide (SiCh).

7. The image sensor structure of any of claims 1-6, wherein the substrate comprises silicon.

8. The image sensor structure of any of claims 1-7, wherein a subset of adjacent ones of the plurality of pillar structures corresponds to a single pixel element.

9. The image sensor structure of claim 8, wherein: the subset of adjacent ones of the plurality of pillar structures is configured to direct a first color of the plurality of colors of the incident light to a first optical-to-electrical conversion element of the plurality of optical-to-electrical conversion elements and a second color of the plurality of colors of the incident light to a second optical-to-electrical conversion element of the plurality of optical-to-electrical conversion elements, the first color is different than the second color, and the first optical-to-electrical conversion element is different than the second optical-to- electrical conversion element.

10. The image sensor structure of any of claims 8-9, wherein at least one of a width or a length of the single pixel element is between 0.2 micrometers (pm) and 20.6 pm.

11. The image sensor structure of any of claims 1-10, further comprising: a color filtering layer disposed between the substrate and the optical-to-electrical conversion layer, the color filtering layer comprising a plurality of color filtering regions, wherein the plurality of pillar structures is further configured to direct a respective color of the plurality of colors of the incident light to a corresponding one of the plurality of color filtering regions that is configured to pass through light of the respective color.Atty. Docket No. 4502-86801 (6000766PCT02)12. The image sensor structure of claim 11, wherein the plurality of color filtering regions comprises at least one of a green color filtering region, a blue color filtering region, or a red color filtering region.

13. The image sensor structure of claim 12, wherein at least one of: the red color filtering region has a passband less than 100 nanometers (nm), the blue color filtering region has a passband less than lOOnm, or the green color filtering region has a passband less than 50 nm.

14. The image sensor structure of any of claims 1-13, further comprising: a photo shielding element extending from the substrate towards and through at least a portion of the optical-to-electrical conversion layer and separating a pair of adjacent optical-to-electrical conversion elements of the plurality of optical-to-electrical conversion elements.

15. The image sensor structure of claim 14, wherein a dimension of the photo shielding element along a second axis parallel to the surface of the substrate is between 90 nanometers (nm) and 1100 nm.

16. The image sensor structure of any of claims 14-15, wherein the photo shielding element comprises a metal material.

17. An electronic device comprising: an image sensor comprising an array of pixel elements, each comprising: an optical-to-electrical conversion layer comprising a plurality of optical-to-electrical conversion elements; and an optical signal routing layer adjacent to the optical-to-electrical conversion layer along an axis, the optical routing layer comprising a plurality of pillar structures extending along the axis and configured to direct a plurality of colors of an incident light to corresponding ones of the plurality of optical-to-electrical conversion elements, wherein at least a first pillar structure of the plurality of pillar structures has a different height than a second pillar structure of the plurality of pillar structures; andAtty. Docket No. 4502-86801 (6000766PCT02) an electrical signal processing component coupled to the image sensor.

18. The electronic device of claim 17, wherein the plurality of pillar structures comprises titanium dioxide (TiCh), silicon nitride (SiNx), silicon (Si), or silicon dioxide (SiCh).

19. The electronic device of any of claims 17-18, further comprising: a color filtering layer disposed between the optical-to-electrical conversion layer and the optical signal routing layer, the color filtering layer comprising a plurality of color filtering regions, wherein the plurality of pillar structures is further configured to direct a respective color of the plurality of colors of the incident light to a corresponding one of the plurality of color filtering regions that is configured to pass through light of the respective color.

20. The electronic device of claim 19, wherein the plurality of color filtering regions comprises at least one of a green color filtering region, a blue color filtering region, or a red color filtering region.

21. The electronic device of any of claims 19-20, wherein at least two of the plurality of color filtering regions passes through the same color light.

22. A method of providing an image sensor, the method comprising: providing an optical-to-electrical conversion layer, wherein the optical-to-electrical conversion layer comprises a plurality of optical-to-electrical conversion elements; and providing an optical signal routing layer on a surface of the optical-to-electrical conversion layer, wherein the optical signal routing layer comprises a plurality of pillar structures extending away from the surface of the optical-to-electrical conversion layer and configured to direct a plurality of colors of an incident light to corresponding ones of the plurality of optical-to-electrical conversion elements, and wherein at least a first pillar structure of the plurality of pillar structures has a different height than a second pillar structure of the plurality of pillar structures.

23. The method of claim 22, wherein the providing the optical signal routing layer comprises: forming the plurality of pillar structures using a pattern transfer process.Atty. Docket No. 4502-86801 (6000766PCT02)24. The method of any of claims 22-23, wherein the providing the optical signal routing layer comprises: determining heights of individual ones of the plurality of pillar structures based on an evaluation against a set of target routing paths to direct the plurality of colors of an incident light to corresponding ones of the plurality of optical-to-electrical conversion elements.

25. The method of claim 24, wherein the determining the heights of the individual ones of the plurality of pillar structures comprises: varying a height of an individual one of the plurality of pillar structures within a predetermined range.

26. The method of any of claims 22-25, wherein the providing the optical signal routing layer comprises: determining heights of individual ones of the plurality of pillar structures based on an artificial intelligence (Al)-based on an inverse design process.

27. The method of any of claims 22-26, further comprising: providing a color filtering layer between the optical-to-electrical conversion layer and the optical signal routing layer, wherein: the color filtering layer comprises a plurality of color filtering regions, and the plurality of pillar structures is further configured to direct a respective color of the plurality of colors of the incident light to a corresponding one of the plurality of color filtering regions that is configured to pass through light of the respective color.

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