Image sensor with color separation lens array and electronic device including same

Abstract

To provide an image sensor including a color separation lens array for converging light after separating incident light for each wavelength, and an electronic device including the same.SOLUTION: In an image sensor, a pixel array 1100 includes: a sensor substrate 110 including a first photosensitive cell and a second photosensitive cell for sensing light; and a color separation lens array 130 including a first region 131 facing the first photosensitive cell 111 and including a first nanopost NP and a second region 132 facing the second photosensitive cell 112 and including a second nanopost NP. The first nanopost and the second nanopost branch incident light that enters the color separation lens array 130 into light with a first wavelength and light with a second wavelength, which are different from each other, in different directions, and form phase distributions of light converged on the first photosensitive cell and the second photosensitive cell at the respective positions passing the first region and the second region.SELECTED DRAWING: Figure 4A

Description

[Technical Field]

[0001] The present invention relates to an image sensor having a color separation lens array and an electronic device including the image sensor, and more particularly to an image sensor having a color separation lens array that can separate and focus incident light according to wavelength, and an electronic device including the image sensor. [Background technology]

[0002] Image sensors generally use color filters to detect the color of incident light. However, color filters reduce light utilization efficiency by absorbing the remaining colors except for the light of the color of interest. For example, when using an RGB color filter, only one-third of the incident light is transmitted and the remaining two-thirds is absorbed, resulting in a light utilization efficiency of only about 33%. Therefore, in color display devices and color image sensors, most of the light loss occurs in the color filters. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 9,653,501 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention provides an image sensor with improved light utilization efficiency by using a color separation lens array that can separate and condense incident light according to wavelength.

[0005] Another problem to be solved by the present invention is to provide an electronic device including the image sensor. [Means for solving the problem]

[0006] An image sensor according to an embodiment includes: a sensor substrate including first and second photosensitive cells that detect light; and a color separation lens array including a first region facing the first photosensitive cells and including first nanoposts, and a second region facing the second photosensitive cells and including second nanoposts, wherein the first and second nanoposts are different from each other in at least one of shape, size, and arrangement, and the first and second nanoposts may split light having a first wavelength and light having a second wavelength, which are different from each other, of incident light entering the color separation lens array into different directions, and form phase distributions of the light that are focused on the first and second photosensitive cells, respectively, at positions after passing through the first and second regions. The first nanoposts and the second nanoposts can cause the light of the first wavelength to form a phase distribution of 2Nπ at the positions corresponding to the centers of the first photosensitive cells and a phase distribution of (2N-1)π at the positions corresponding to the centers of the second photosensitive cells immediately after passing through the color separation lens array, where N is an integer greater than 0.

[0007] The first nanoposts and the second nanoposts can cause the light of the second wavelength to form a phase distribution of (2M-1)π at the positions corresponding to the centers of the first photosensitive cells and a phase distribution of 2Mπ at the positions corresponding to the centers of the second photosensitive cells immediately after passing through the color separation lens array, where M is an integer greater than 0.

[0008] The image sensor may further include a spacer layer disposed between the sensor substrate and the color separation lens array, forming a distance between the sensor substrate and the color separation lens array.

[0009] The spacer layer may have a thickness corresponding to the color separation lens array at a center wavelength of a wavelength band of incident light that is color-separated by the color separation lens array.

[0010] The theoretical thickness of the spacer layer is ht , the pitch of the photosensitive cells is p, the refractive index of the spacer layer is n, and the central wavelength of the wavelength band of light that is color-separated by the color separation lens array is λ0, then the theoretical thickness of the spacer layer is h t teeth,

[0011]

number

[0012] and the actual thickness h of the spacer layer is h t -p≦h≦h t +p. The sensor substrate may further include third and fourth photosensitive cells that detect light, and the color separation lens array may include a third region facing the third photosensitive cells and including third nanoposts, and a fourth region facing the fourth photosensitive cells and including fourth nanoposts, and the third nanoposts and the fourth nanoposts may be different from each other in at least one of shape, size, and arrangement.

[0013] The first to fourth nanoposts can form a phase distribution at a position where the light has passed through the first to fourth regions, in which light beams having a first wavelength, a second wavelength, and a third wavelength, which are different from one another, are split into beams in different directions from one another, and the light beams having the first wavelength are focused on the first photosensitive cell and the fourth photosensitive cell, the light beams having the second wavelength are focused on the second photosensitive cell, and the light beams having the third wavelength are focused on the third photosensitive cell.

[0014] The first wavelength is green light, the second wavelength is blue light, and the third wavelength is also red light.

[0015] The first to fourth nanoposts may be configured so that, immediately after passing through the color separation lens array, the light of the first wavelength forms a phase distribution of 2Nπ at positions corresponding to the central parts of the first and fourth photosensitive cells, and forms a phase distribution of (2N-1)π at positions corresponding to the central parts of the second and third photosensitive cells, where N is an integer greater than 0.

[0016] The first to fourth nanoposts may be configured so that, immediately after passing through the color separation lens array, the light of the second wavelength forms a phase distribution of (2M-1)π at positions corresponding to the central parts of the first and fourth photosensitive cells, a phase distribution of 2Mπ at positions corresponding to the central part of the second photosensitive cell, and a phase distribution larger than (2M-2)π and smaller than (2M-1)π at a position corresponding to the central part of the third photosensitive cell.

[0017] The first to fourth nanoposts may be configured so that, immediately after passing through the color separation lens array, the light of the third wavelength forms a phase distribution of (2L-1)π at positions corresponding to the central parts of the first and fourth photosensitive cells, a phase distribution of 2Lπ at a position corresponding to the central part of the third photosensitive cell, and a phase distribution larger than (2L-2)π and smaller than (2L-1)π at a position corresponding to the central part of the second photosensitive cell, where L is an integer larger than 0.

[0018] The image sensor has a pixel array structure in which a plurality of unit pixels including red, green, and blue pixels are arranged in a Bayer pattern, and the nanoposts provided in the first to fourth regions corresponding to the green pixels may have different distribution patterns along a first direction and a second direction perpendicular to the first direction.

[0019] In the first to fourth regions, the nanoposts provided in the regions corresponding to blue and red pixels may have a symmetrical distribution pattern along the first and second directions.

[0020] In the first to fourth regions, the nanoposts located at the center of the region corresponding to the green pixel may have a larger cross-sectional area than the nanoposts provided in the regions corresponding to the other color pixels.

[0021] In the first to fourth regions, the nanoposts provided in the regions corresponding to the green pixels may have a cross-sectional area such that the nanoposts arranged in the center have a larger cross-sectional area than the nanoposts arranged in the periphery.

[0022] The color separation lens array may further include a plurality of first regions and a plurality of second regions that are arranged to protrude from an edge of the sensor substrate and that do not face any of the photosensitive cells of the sensor substrate in the vertical direction.

[0023] At least one of the first nanoposts and the second nanoposts includes a lower post and an upper post stacked on the lower post, and the lower post and the upper post are stacked such that they are offset from each other.

[0024] The degree of misalignment between the lower post and the upper post increases from the center to the periphery of the image sensor.

[0025] According to another embodiment, the image sensor includes a sensor substrate including a plurality of first photosensitive cells and a plurality of second photosensitive cells alternately arranged along a first row, and a plurality of third photosensitive cells and a plurality of fourth photosensitive cells alternately arranged along a second row adjacent to the first row; and a color separation lens array including a plurality of first regions facing the plurality of first photosensitive cells, each including a first nanopost, a plurality of second regions facing the plurality of second photosensitive cells, each including a second nanopost, a plurality of third regions facing the plurality of third photosensitive cells, each including a third nanopost, and a plurality of fourth regions facing the plurality of fourth photosensitive cells, each including a fourth nanopost. The shapes, sizes and arrangements of the first to fourth nanoposts may be set so that light of a first wavelength is focused on a first photosensitive cell located below the first region, light of a second wavelength is branched to a second photosensitive cell adjacent to the first photosensitive cell in the horizontal direction, light of a third wavelength is branched to a third photosensitive cell adjacent to the first photosensitive cell in the vertical direction, and light of a second wavelength, among light incident on the second region, is focused on a second photosensitive cell located immediately below the second region, light of the first wavelength is branched to a first photosensitive cell adjacent to the second photosensitive cell in the horizontal direction and a fourth photosensitive cell adjacent to the second photosensitive cell in the vertical direction, and light of a third wavelength is branched to a third photosensitive cell diagonally adjacent to the second photosensitive cell.

[0026] The light of the first wavelength is green light, the light of the second wavelength is blue light, and the light of the third wavelength is red light.

[0027] An electronic device according to another embodiment may include an imaging unit that focuses light reflected from a subject to form an optical image, and any one of the image sensors described above that converts the optical image formed by the imaging unit into an electrical signal.

[0028] The electronic device may be a smartphone, a mobile phone, a personal digital assistant (PDA), a laptop, a personal computer (PC), a home appliance, a security camera, a medical camera, a car, or an Internet of Things (IoT) device. [Effects of the Invention]

[0029] The disclosed color separation lens array can separate and focus incident light by wavelength without absorbing or blocking it, thereby improving the light utilization efficiency of an image sensor. Furthermore, an image sensor using the disclosed color separation lens array can maintain the Bayer pattern method commonly used in image sensors, and can utilize the pixel structure and image processing algorithms of existing image sensors. Furthermore, an image sensor using the disclosed color separation lens array does not require a separate microlens to focus light onto pixels. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 is a block diagram of an image sensor according to one embodiment. [Figure 2A] 1 is a diagram illustrating various exemplary pixel arrangements of a pixel array of an image sensor; [Figure 2B] 1 is a diagram illustrating various exemplary pixel arrangements of a pixel array of an image sensor; [Figure 2C] 1 is a diagram illustrating various exemplary pixel arrangements of a pixel array of an image sensor; [Figure 3] 1 is a conceptual diagram illustrating the general structure and operation of a color separation lens array according to one embodiment. [Figure 4A] 1A-1C are schematic cross-sectional views of a pixel array of an image sensor according to one embodiment, shown at different cross sections; [Figure 4B]1A-1C are schematic cross-sectional views of a pixel array of an image sensor according to one embodiment, shown at different cross sections; [Figure 5A] FIG. 2 is a plan view schematically illustrating an arrangement of photosensitive cells in a pixel array of an image sensor. [Figure 5B] 10 is a plan view illustrating an example of a pixel array of an image sensor in which a plurality of nanoposts are arranged in a plurality of regions of a color separation lens array. [Figure 5C] FIG. 5C is an enlarged plan view showing a portion of FIG. 5B in detail. [Figure 6A] 10 is a diagram showing a phase distribution of blue light that has passed through a color separation lens array. [Figure 6B] 10 is a diagram showing a computer-simulated blue light focusing distribution in a photosensitive cell facing a color separation lens array; [Figure 6C] 10 is a diagram illustrating an example of a second region of a color separation lens array corresponding to a blue pixel and the traveling direction of blue light incident on the periphery thereof; [Figure 6D] 10 is a diagram illustrating an example of a microlens array that functions equivalently to a color separation lens array for blue light. [Figure 7A] 10 is a diagram showing the phase distribution of green light that has passed through a color separation lens array. [Figure 7B] 10 is a diagram showing a computer-simulated green light focusing distribution in a photosensitive cell facing a color separation lens array; [Figure 7C] 10 is a diagram illustrating an example of a first region of a color separation lens array corresponding to a green pixel and the traveling direction of green light incident on the periphery thereof; [Figure 7D] 10 is a diagram illustrating an example of a microlens array that functions equivalently to a color separation lens array for green light. [Figure 8A] 10 is a diagram showing the phase distribution of red light that has passed through a color separation lens array. [Figure 8B] 10 is a diagram showing a computer-simulated red light focusing distribution in a photosensitive cell facing a color separation lens array; [Figure 8C]10 is a diagram illustrating an example of a third region of a color separation lens array corresponding to a red pixel and the traveling direction of red light incident on the periphery thereof; [Figure 8D] 10 is a diagram illustrating an example of a microlens array that functions equivalently to a color separation lens array for red light. [Figure 9A] 10 is a diagram illustrating an example of the traveling direction of light incident on a region corresponding to a blue pixel, according to color; [Figure 9B] 10 is a diagram illustrating an example of the traveling direction of light incident on a region corresponding to a green pixel according to color; [Figure 9C] 10 is a diagram illustrating an example of the traveling direction of light incident on a region corresponding to a red pixel according to color; [Figure 10A] 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the photosensitive cells have a pitch of 0.7 μm. [Figure 10B] 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the photosensitive cells have a pitch of 0.7 μm. [Figure 10C] 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the photosensitive cells have a pitch of 0.7 μm. [Figure 10D] 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the photosensitive cells have a pitch of 0.7 μm. [Figure 10E] 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the photosensitive cells have a pitch of 0.7 μm. [Figure 11A] 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the photosensitive cells have a pitch of 0.8 μm. [Figure 11B]10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the photosensitive cells have a pitch of 0.8 μm. [Figure 11C] 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the photosensitive cells have a pitch of 0.8 μm. [Figure 11D] 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the photosensitive cells have a pitch of 0.8 μm. [Figure 11E] 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the photosensitive cells have a pitch of 0.8 μm. [Figure 12A] 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the photosensitive cells have a pitch of 1.0 μm. [Figure 12B] 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the photosensitive cells have a pitch of 1.0 μm. [Figure 12C] 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the photosensitive cells have a pitch of 1.0 μm. [Figure 12D] 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the photosensitive cells have a pitch of 1.0 μm. [Figure 12E] 10 is a graph showing an example of how the efficiency of a color separation lens array changes depending on the distance between the color separation lens array and the sensor substrate when the photosensitive cells have a pitch of 1.0 μm. [Figure 13] 1A and 1B are perspective views illustrating exemplary configurations of nanoposts that may also be employed in a color separation lens array of an image sensor according to an embodiment. [Figure 14A]10A and 10B are plan views illustrating exemplary shapes of nanoposts that may also be employed in color separation lens arrays of image sensors according to other embodiments. [Figure 14B] 10A and 10B are plan views illustrating exemplary shapes of nanoposts that may also be employed in color separation lens arrays of image sensors according to other embodiments. [Figure 14C] 10A and 10B are plan views illustrating exemplary shapes of nanoposts that may also be employed in color separation lens arrays of image sensors according to other embodiments. [Figure 14D] 10A and 10B are plan views illustrating exemplary shapes of nanoposts that may also be employed in color separation lens arrays of image sensors according to other embodiments. [Figure 14E] 10A and 10B are plan views illustrating exemplary shapes of nanoposts that may also be employed in color separation lens arrays of image sensors according to other embodiments. [Figure 14F] 10A and 10B are plan views illustrating exemplary shapes of nanoposts that may also be employed in color separation lens arrays of image sensors according to other embodiments. [Figure 14G] 10A and 10B are plan views illustrating exemplary shapes of nanoposts that may also be employed in color separation lens arrays of image sensors according to other embodiments. [Figure 14H] 10A and 10B are plan views illustrating exemplary shapes of nanoposts that may also be employed in color separation lens arrays of image sensors according to other embodiments. [Figure 15] 10 is a plan view illustrating an example of an arrangement of a plurality of nanoposts forming a color separation lens array of an image sensor according to another embodiment. [Figure 16] 10 is a plan view illustrating an exemplary arrangement of a plurality of nanoposts forming a color separation lens array of an image sensor according to yet another embodiment. [Figure 17] 10 is a plan view illustrating an exemplary arrangement of a plurality of nanoposts forming a color separation lens array of an image sensor according to yet another embodiment. [Figure 18] 10 is a plan view illustrating an exemplary arrangement of a plurality of nanoposts forming a color separation lens array of an image sensor according to yet another embodiment. [Figure 19]20 is a graph showing an example of the spectral distribution of light incident on red, green, and blue pixels of an image sensor having the color separation lens array of FIG. 18; [Figure 20A] 10A to 10C are cross-sectional views showing a schematic structure of a pixel array of an image sensor according to another embodiment, each taken along a different cross section. [Figure 20B] 10A to 10C are cross-sectional views showing a schematic structure of a pixel array of an image sensor according to another embodiment, each taken along a different cross section. [Figure 21] 10 is a graph illustrating an example of spectral distributions of light incident on red, green, and blue pixels of an image sensor according to an embodiment, in which color filters are provided; [Figure 22] 10 is a graph illustrating an example of spectral distributions of light incident on red, green, and blue pixels of an image sensor according to an embodiment, in the case where no color filters are provided; [Figure 23] 10A and 10B are plan views illustrating an example of a color separation lens array according to another embodiment. [Figure 24] 24 is a cross-sectional view showing a schematic structure of a pixel array of an image sensor including the color separation lens array shown in FIG. 23. [Figure 25] FIG. 10 is a cross-sectional view showing a schematic structure of an image sensor according to yet another embodiment. [Figure 26] 26A and 26B are perspective views illustrating exemplary shapes of nanoposts employed in the color separation lens array of the image sensor of FIG. 25. [Figure 27] 1 is a block diagram that schematically illustrates an electronic device including an image sensor according to one embodiment. [Figure 28] 1 is a diagram illustrating an example of an electronic device to which an image sensor according to an embodiment is applied. [Figure 29] 1 is a diagram illustrating another example of an electronic device to which an image sensor according to an embodiment is applied. [Figure 30] 1 is a diagram illustrating yet another example of an electronic device to which an image sensor according to an embodiment is applied. [Figure 31] 1 is a diagram illustrating yet another example of an electronic device to which an image sensor according to an embodiment is applied. [Figure 32] 1 is a diagram illustrating yet another example of an electronic device to which an image sensor according to an embodiment is applied. [Figure 33] 1 is a diagram illustrating yet another example of an electronic device to which an image sensor according to an embodiment is applied. [Figure 34] 1 is a diagram illustrating yet another example of an electronic device to which an image sensor according to an embodiment is applied. [Figure 35] 1 is a diagram illustrating yet another example of an electronic device to which an image sensor according to an embodiment is applied. [Figure 36] 1 is a diagram illustrating yet another example of an electronic device to which an image sensor according to an embodiment is applied. [Figure 37] 1 is a diagram illustrating yet another example of an electronic device to which an image sensor according to an embodiment is applied. [Figure 38] 1 is a diagram illustrating yet another example of an electronic device to which an image sensor according to an embodiment is applied. DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, an image sensor having a color separation lens array and an electronic device including the same will be described in detail with reference to the accompanying drawings. The described embodiments are merely exemplary, and various modifications are possible from such embodiments. In the following drawings, the same reference numerals refer to the same components, and the size of each component may be exaggerated in the drawings for clarity and convenience of explanation.

[0032] In the following, the expression "top" or "above" includes not only what is in contact with something and is immediately above, below, left or right of it, but also what is not in contact with something and is immediately above, below, left or right of it.

[0033] Terms such as "first" and "second" may be used to describe various components, but are used only to distinguish one component from another, and are not intended to limit the materials or structures of the components.

[0034] The singular expression includes the plural expression unless the context clearly indicates otherwise. Furthermore, when a part "comprises" a certain element, it does not mean that it excludes other elements, but that it may further include other elements, unless otherwise specified to the contrary.

[0035] In addition, terms such as "unit" and "module" used in the specification refer to a unit that processes a function or operation, and may be realized by hardware or software, or by a combination of hardware and software.

[0036] Use of the term "said" and similar referents can refer to both the singular and the plural.

[0037] The steps constituting the method may be performed in any suitable order unless expressly stated to be performed in the order described. Furthermore, the use of all exemplary terms (e.g., "for example") is merely for the purpose of illustrating the technical idea in detail, and such terms do not limit the scope of the claims, except as otherwise limited by the claims.

[0038] 1 is a schematic block diagram of an image sensor according to an embodiment. Referring to FIG. 1, the image sensor 1000 may include a pixel array 1100, a timing controller 1010, a row decoder 1020, and an output circuit 1030. The image sensor 1000 may be a charge coupled device (CCD) image sensor or a complementary metal oxide semiconductor (CMOS) image sensor.

[0039] The pixel array 1100 includes pixels arranged two-dimensionally along a plurality of rows and columns. The row decoder 1020 selects one of the rows of the pixel array 1100 in response to a row address signal output from the timing controller 1010. The output circuit 1030 outputs a photo-sensing signal in units of columns from a plurality of pixels arranged along the selected row. To this end, the output circuit 1030 may include a column decoder and an analog-to-digital converter (ADC). For example, the output circuit 1030 may include a column decoder and a plurality of ADCs arranged for each column between the pixel array 1100, or a single ADC arranged at the output end of the column decoder. The timing controller 1010, the row decoder 1020, and the output circuit 1030 may be implemented on a single chip or on separate chips. A processor for processing the video signal output via the output circuit 1030 is also implemented on one chip together with the timing controller 1010, the row decoder 1020, and the output circuit 1030.

[0040] The pixel array 1100 may include multiple pixels that are sensitive to light of different wavelengths, and the pixels may be arranged in various ways, such as those shown in Figures 2A to 2C.

[0041] First, FIG. 2A shows a Bayer pattern commonly used in image sensors 1000. Referring to FIG. 2, one unit pixel includes four quadrant regions, and the first through fourth quadrant regions are blue, green, red, and green pixels B, G, R, and G, respectively. Such unit pixels are two-dimensionally and repeatedly arranged along a first direction (X direction) and a second direction (Y direction). In other words, in a 2×2 array of unit pixels, two green pixels G are arranged in one diagonal direction, and one blue pixel B and one red pixel R are arranged in the other diagonal direction. Looking at the overall pixel arrangement, a first row in which a plurality of green pixels G and a plurality of blue pixels B are alternately arranged along the first direction, and a second row in which a plurality of red pixels R and a plurality of green pixels G are alternately arranged along the first direction are repeatedly arranged.

[0042] However, the arrangement of the pixel array 1100 is not limited to the Bayer pattern, and various other arrangements are possible. For example, referring to FIG. 2B, a CYGM arrangement is also possible, in which a magenta pixel (M), a cyan pixel (C), a yellow pixel (Y), and a green pixel (G) constitute one unit pixel. Referring to FIG. 2C, an RGBW arrangement is also possible, in which a green pixel G, a red pixel R, a blue pixel B, and a white pixel (W) constitute one unit pixel. Although not shown, the unit pixels may also have a 3×2 array. Alternatively, the pixels of the pixel array 1100 may be arranged in various other ways depending on the color characteristics of the image sensor 1000. For convenience, the pixel array 1100 of the image sensor 1000 will be described below as having a Bayer pattern. However, the principles of the embodiments described below may be applied to pixel arrangements of other types than the Bayer pattern.

[0043] According to an embodiment, the pixel array 1100 of the image sensor 1000 may include a color separation lens array configured to focus light of a corresponding color onto each pixel. FIG. 3 is a conceptual diagram illustrating the general structure and operation of a color separation lens array according to an embodiment. Referring to FIG. 3, the color separation lens array 130 includes nanopost NPs arranged on the same plane according to a predetermined rule. Such a color separation lens array 130 is also disposed on the spacer layer 120.

[0044] Here, this rule applies to parameters such as the shape, size (width, height), spacing, and arrangement of nanopost NPs, and the incident light L i The target phase distribution TP is also determined by the target phase distribution TP realized by the color separation lens array 130 with respect to the incident light L i The target phase distribution TP is also determined by considering target areas R1 and R2 that separate and focus the wavelengths of the incident light L. The target phase distribution TP is shown between the color separation lens array 130 and the target areas R1 and R2, but this is merely for convenience of illustration. The actual target phase distribution TP is determined by considering the wavelengths of the incident light L. i means the phase distribution at a position immediately after the light passes through the color separation lens array 130, for example, at the lower surface of the color separation lens array 130 or at the upper surface of the spacer layer 120.

[0045] The color separation lens array 130 may include a first region 131 and a second region 132, each of which may include one or more nanopost NPs. The first region 131 and the second region 132 are arranged to face the first target region R1 and the second target region R2, respectively, and may correspond one-to-one. While the first region 131 and the second region 132 are illustrated as having three nanopost NPs each, this is merely an example. While the nanopost NPs are illustrated as being entirely located within either the first region 131 or the second region 132, this is not limiting, and some nanopost NPs may also be located at the boundary between the first region 131 and the second region 132. The nanopost NPs located in the first region 131 are first nanoposts, and the nanopost NPs located in the second region 132 are second nanoposts (this also applies to other embodiments).

[0046] The nanoposts NPs of the color separation lens array 130 separate the incident light L i It is possible to form a phase distribution that splits and focuses light of different wavelengths contained in the incident light L in different directions. i The light of the first wavelength L contained in λ1 has a first phase distribution and a second wavelength of light L λ2 The shape, size, arrangement, etc. of the nanoposts NP distributed in the first region 131 and the second region 132 are determined so as to form a target phase distribution TP having a second phase distribution. With such a target phase distribution TP, the nanoposts NP and the target regions R1 and R2 at a predetermined separation distance A are irradiated with light L of a first wavelength, respectively. λ1 and the second wavelength light L λ2 and can be collected.

[0047] The arrangement order of the nanopost NPs in the first region 131 may be different from the arrangement order of the nanopost NPs in the second region 132. In other words, any one of the shape, size, and arrangement of the first nanopost NPs provided in the first region 131 may be different from the shape, size, and arrangement of the second nanopost NPs provided in the second region 132.

[0048] The nanopost NP may have a shape dimension of a sub-wavelength smaller than the wavelength band to be split. The nanopost NP may have a shape dimension smaller than the shorter wavelength of the first wavelength or the second wavelength, and the incident light L i is visible light, it can have dimensions of, for example, less than 400 nm, 300 nm or 200 nm.

[0049] Nanopost NPs can also be made of a material with a higher refractive index than the surrounding material. For example, nanopost NPs can be made of single-crystal silicon (c-Si), polysilicon (p-Si), amorphous silicon (a-Si), III-V compound semiconductors (GaP, GaN, GaAs, etc.), SiC, TiO2, SiN, and / or combinations thereof. Nanopost NPs, which have a refractive index different from that of the surrounding material, can change the phase of light passing through them. This is due to a phase delay caused by the subwavelength shape, and the degree of phase delay is determined by the detailed shape and arrangement of the nanopost NPs. The surrounding material can also be a dielectric material with a lower refractive index than the nanopost NPs, such as SiO2 or air.

[0050] The first wavelength λ1 and the second wavelength λ2 may be in the visible light wavelength band, but are not limited thereto, and various wavelength bands may be realized depending on the rules regarding the shape, size, spacing, arrangement, etc. of the arranged nanopost NPs. While Fig. 3 illustrates an example in which two wavelengths are split and focused, the present invention is not limited thereto, and incident light can be split into three or more directions depending on the wavelength and still be focused.

[0051] An example in which the above-described color separation lens array 130 is applied to the pixel array 1100 of the image sensor 1000 will be described in more detail below.

[0052] 4A and 4B are cross-sectional views of a pixel array according to an embodiment, FIG. 5A is a plan view showing the arrangement of photosensitive cells in the pixel array, and FIG. 5B is a plan view showing an example of the arrangement of nanoposts in a color separation lens array.

[0053] 4A and 4B, the pixel array 1100 includes a sensor substrate 110 including a plurality of photosensitive cells 111, 112, 113, and 114 for sensing light, a transparent spacer layer 120 disposed on the sensor substrate 110, and a color separation lens array 130 disposed on the spacer layer 120.

[0054] The sensor substrate 110 may include first, second, third, and fourth photosensitive cells 111, 112, 113, and 114 that convert light into an electrical signal. For example, as shown in FIG. 4A , the first and second photosensitive cells 111 and 112 may be alternately arranged along a first direction (X direction), and in a cross section at a different position in the Y direction, as shown in FIG. 4B , the third and fourth photosensitive cells 113 and 114 may be alternately arranged. Such region division is intended to divide and sense incident light in pixel units. For example, the first and fourth photosensitive cells 111 and 114 may sense light of a first wavelength corresponding to a first pixel, the second photosensitive cell 112 may sense light of a second wavelength corresponding to a second pixel, and the third photosensitive cell 113 may sense light of a third wavelength corresponding to a third pixel. In the following description, the first wavelength light is green light, the second wavelength light is blue light, and the third wavelength light is red light, and the first pixel, the second pixel, and the third pixel are a green pixel G, a blue pixel B, and a red pixel R, respectively. Although not shown, a separation film for separating cells may be further formed at the boundary between the cells.

[0055] The spacer layer 120 supports the color separation lens array 130 and maintains a constant distance between the sensor substrate 110 and the color separation lens array 130. The spacer layer 120 is made of a material that is transparent to visible light. For example, the spacer layer 120 may be made of a dielectric material that has a refractive index lower than that of the nanopost NPs of the color separation lens array 130 and low absorption in the visible light band, such as SiO2 or siloxane-based spin-on glass (SOG).

[0056] The color separation lens array 130 includes nanopost NPs arranged according to a predetermined pattern. Although not shown, the color separation lens array 130 may further include a protective layer for protecting the nanopost NPs. The protective layer may be made of a dielectric material having a refractive index lower than that of the material forming the nanopost NPs.

[0057] The color separation lens array 130 is divided into a plurality of regions 131, 132, 133, and 134 that face the plurality of photosensitive cells 111, 112, 113, and 114 in a one-to-one correspondence. One or a plurality of nanopost NPs are arranged in each of the plurality of regions 131, 132, 133, and 134, and any one of the shape, size, and arrangement of the nanoposts NPs may differ depending on the region.

[0058] The color separation lens array 130 is divided into regions so that light of a first wavelength is split and focused to the first photosensitive cell 111 and the fourth photosensitive cell 114, light of a second wavelength is split and focused to the second photosensitive cell 112, and light of a third wavelength is split and focused to the third photosensitive cell 113, and the size, shape, and arrangement of the nanopost NPs are determined for each region.

[0059] 2A , the first photosensitive cell 111 and the fourth photosensitive cell 114 in FIG. 5A correspond to the green pixel G, the second photosensitive cell 112 corresponds to the blue pixel B, and the third photosensitive cell 113 corresponds to the red pixel R. Referring to FIG. 5B , the first region 131 and the fourth region 134 of the color separation lens array 130 correspond to the green pixel G, the second region 132 corresponds to the blue pixel B, and the third region 133 corresponds to the red pixel R. Therefore, the color separation lens array 130 includes a plurality of unit pattern arrays arranged two-dimensionally, and each unit pattern array includes the first region 131, the second region 132, the third region 133, and the fourth region 134 arranged in a 2×2 pattern.

[0060] As shown in FIG. 5B , the first region 131 and fourth region 134 corresponding to the green pixel G, the second region 132 corresponding to the blue pixel B, and the third region 133 corresponding to the red pixel R may include cylindrical nanoposts NPs with circular cross sections. The nanoposts NPs arranged in the third region 133 are third nanoposts, and the nanoposts NPs arranged in the fourth region 134 are fourth nanoposts (this is also true in other embodiments). Nanoposts NPs with different cross-sectional areas are arranged in the centers of the first region 131, second region 132, third region 133, and fourth region 134, and nanoposts NPs may also be arranged at the centers of the inter-pixel boundaries and at the intersections of the pixel boundaries. The cross-sectional areas of the nanoposts NPs arranged at the inter-pixel boundaries may be narrower than those of the nanoposts NPs arranged in the center of the pixels.

[0061] FIG. 5C shows in detail a portion of FIG. 5B , i.e., the nanopost NP arrangement in the first region 131 to the fourth region 134 that constitute the unit pattern array. In FIG. 5C , the nanopost NPs are labeled p1 to p9 according to their detailed positions within the unit pattern array. Referring to FIG. 5C , the cross-sectional areas of the nanopost p1 located at the center of the first region 131 and the nanopost p4 located at the center of the fourth region 134 are larger than the cross-sectional areas of the nanopost p2 located at the center of the second region 132 and the nanopost p3 located at the center of the third region 133, and the cross-sectional area of ​​the nanopost p2 located at the center of the second region 132 is larger than the cross-sectional area of ​​the nanopost p3 located at the center of the third region 133. However, this is merely one example, and nanopost NPs of various shapes, sizes, and arrangements can be applied as needed.

[0062] The nanoposts NP provided in the first region 131 and the fourth region 134 corresponding to the green pixel G may have different distribution patterns along the first direction (X direction) and the second direction (Y direction). For example, the nanoposts NP arranged in the first region 131 and the fourth region 134 may have different size arrangements along the first direction (X direction) and the second direction (Y direction). As shown in FIG. 5C , the cross-sectional area of ​​the nanopost p5 located at the boundary between the first region 131 and the second region 132 adjacent thereto in the first direction (X direction) is different from the cross-sectional area of ​​the nanopost p6 located at the boundary between the first region 131 and the third region 133 adjacent thereto in the second direction (Y direction). Similarly, the cross-sectional area of ​​nanopost p7 located at the boundary between the fourth region 134 and the third region 133 adjacent to it in the first direction (X direction) is different from the cross-sectional area of ​​nanopost p8 located at the boundary between the fourth region 134 and the second region 132 adjacent to it in the second direction (Y direction).

[0063] Meanwhile, the nanoposts NP arranged in the second region 132 corresponding to the blue pixel B and the third region 133 corresponding to the red pixel R may have a symmetrical distribution pattern along the first direction (X direction) and the second direction (Y direction). As shown in Figure 5C, the cross-sectional areas of the nanoposts NP are the same for nanopost p5 arranged at the boundary between pixels adjacent to the second region 132 in the first direction (X direction) and nanopost p8 arranged at the boundary between pixels adjacent to the second region 132 in the second direction (Y direction). Also, the cross-sectional areas of the nanoposts NP are the same for nanopost p7 arranged at the boundary between pixels adjacent to the third region 133 in the first direction (X direction) and nanopost p6 arranged at the boundary between pixels adjacent to the third region 133 in the second direction (Y direction).

[0064] On the other hand, the nanoposts p9 arranged at the four corners of each of the first region 131, the second region 132, the third region 133, and the fourth region 134, that is, at the positions where the four regions intersect, have the same cross-sectional area.

[0065] Such a distribution is due to the pixel arrangement of the Bayer pattern. For both blue pixel B and red pixel R, adjacent pixels in the first direction (X direction) and the second direction (Y direction) are identical as green pixels G, whereas for green pixels G corresponding to the first region 131, adjacent pixels in the first direction (X direction) are blue pixels B and adjacent pixels in the second direction (Y direction) are different from each other. For green pixels G corresponding to the fourth region 134, adjacent pixels in the first direction (X direction) are red pixels R and adjacent pixels in the second direction (Y direction) are different from each other. Furthermore, for green pixels G corresponding to the first region 131 and the fourth region 134, adjacent pixels in the four diagonal directions are identical as green pixels G, for blue pixels B corresponding to the second region 132, adjacent pixels in the four diagonal directions are identical as red pixels R, and for red pixels R corresponding to the third region 133, adjacent pixels in the four diagonal directions are identical as blue pixels B. Therefore, in the second region 132 and the third region 133 corresponding to the blue pixel B and the red pixel R, respectively, the nanoposts NP may be arranged in a form of 4-fold symmetry, and in the first region 131 and the fourth region 134 corresponding to the green pixel G, the nanoposts NP may be arranged in a form of 2-fold symmetry. In particular, the first region 131 and the fourth region 134 are rotated by 90° with respect to each other.

[0066] Although the nanoposts NP are illustrated as having a symmetrical circular cross-sectional shape, this is not limiting and some nanoposts may have an asymmetrical cross-sectional shape. For example, the first region 131 and the fourth region 134 corresponding to the green pixel G may employ nanoposts having an asymmetrical cross-sectional shape with different widths in the first direction (X direction) and the second direction (Y direction), while the second region 132 and the third region 133 corresponding to the blue pixel B and the red pixel R may employ nanoposts having a symmetrical cross-sectional shape with the same widths in the first direction (X direction) and the second direction (Y direction).

[0067] The arrangement pattern of the color separation lens array 130 is merely an example for realizing a target phase distribution in which light of a first wavelength is split and focused at the first photosensitive cell 111 and the fourth photosensitive cell 114, light of a second wavelength is split and focused at the second photosensitive cell 112, and light of a third wavelength is split and focused at the third photosensitive cell 113, but is not limited to the pattern shown in the figure.

[0068] The shape, size and arrangement of the nanoposts NPs provided in each region of the color separation lens array 130 can be determined so that, at a position where the light of the first wavelength has passed through the color separation lens array 130, it forms a phase where it is focused on the first photosensitive cell 111 and the fourth photosensitive cell 114, but does not travel to the adjacent second photosensitive cell 112 and third photosensitive cell 113.

[0069] Similarly, the shape, size and arrangement of the nanoposts NPs provided in each region of the color separation lens array 130 can be determined so that, at a position where the light of the second wavelength has passed through the color separation lens array 130, it forms a phase where it is focused on the second photosensitive cell 112 and does not travel to the adjacent first photosensitive cell 111, third photosensitive cell 113 and fourth photosensitive cell 114.

[0070] Similarly, the shape, size and arrangement of the nanoposts NPs provided in each region of the color separation lens array 130 can be determined so that, at a position where the light of the third wavelength has passed through the color separation lens array 130, it forms a phase where it is focused on the third photosensitive cell 113 and does not travel to the adjacent first, second and fourth photosensitive cells 111, 112 and 114.

[0071] The shape, size, and / or arrangement of the nanopost NPs can be determined to satisfy all of these conditions, and such a color separation lens array 130 can be configured so that light immediately after passing through it has the following target phase distribution: The phase of the light of the first wavelength at a position immediately after passing through the color separation lens array 130, in other words, at the lower surface of the color separation lens array 130 or the upper surface of the spacer layer 120, is 2Nπ at the center of the first region 131 corresponding to the first photosensitive cell 111 and at the center of the fourth region 134 corresponding to the fourth photosensitive cell 114, and also has a distribution showing a phase of (2N−1)π at the center of the second region 132 corresponding to the second photosensitive cell 112 and at the center of the third region 133 corresponding to the third photosensitive cell 113, where N is an integer greater than 0. In other words, immediately after passing through the color separation lens array 130, the phase of the light of the first wavelength is maximum at the center of the first region 131 and the center of the fourth region 134, and gradually decreases concentrically with increasing distance from the center of the first region 131 and the center of the fourth region 134, and is minimum at the center of the second region 132 and the center of the third region 133. For example, when N=1, at the position after passing through the color separation lens array 130, the phase of the green light is 2π at the center of the first region 131 and the center of the fourth region 134, and is also π at the center of the second region 132 and the center of the third region 133. Here, the phase refers to a relative phase value related to the phase of the light immediately before passing through the nanopost NP.

[0072] Furthermore, immediately after passing through the color separation lens array 130, the phase of the light of the second wavelength is 2Mπ at the center of the second region 132 corresponding to the second photosensitive cell 112, is (2M-1)π at the center of the first region 131 corresponding to the first photosensitive cell 111 and at the center of the fourth region 134 corresponding to the fourth photosensitive cell 114, and is greater than (2M-2)π and smaller than (2M-1)π at the center of the third region 133 corresponding to the third photosensitive cell 113. Here, M is an integer greater than 0. In other words, immediately after passing through the color separation lens array 130, the phase of the light of the second wavelength is maximum at the center of the second region 132, and gradually decreases in a concentric pattern with increasing distance from the center of the second region 132, and is locally minimum at the centers of the first region 131, the fourth region 134, and the third region 133. For example, when M=1, the phase of blue light at the position where it passes through the color separation lens array 130 is 2π at the center of the second region 132, π at the center of the first region 131 and the center of the fourth region 134, and approximately 0.2π to 0.7π at the center of the third region 133.

[0073] Similarly, just after passing through the color separation lens array 130, the phase of the light with the third wavelength is 2Lπ at the center of the third region 133 corresponding to the third photosensitive cell 113, is (2L-1)π at the centers of the first region 131 corresponding to the first photosensitive cell 111 and the fourth region 134 corresponding to the fourth photosensitive cell 114, and is larger than (2L-2)π and smaller than (2L-1)π at the center of the second region 132 corresponding to the second photosensitive cell 112. Here, L is an integer larger than 0. In other words, just after passing through the color separation lens array 130, the phase of the light with the third wavelength is maximum at the center of the third region 133, and gradually decreases in a concentric pattern with increasing distance from the center of the third region 133, and is locally minimum at the centers of the first region 131, the fourth region 134, and the second region 132. For example, when L=1, at the position where it passes through the color separation lens array 130, the phase of red light is 2π at the center of the third region 133, π at the center of the first region 131 and the center of the fourth region 134, and approximately 0.2π to 0.7π at the center of the second region 132.

[0074] As mentioned above, the target phase distribution refers to the phase distribution of light at a position immediately after it has passed through the color separation lens array 130. If the light that has passed through the color separation lens array 130 has such a phase distribution, the light of the first to fourth wavelengths will be focused on the first photosensitive cell 111, the second photosensitive cell 112, the third photosensitive cell 113, and the fourth photosensitive cell 114, respectively. In other words, the same optical effect can be achieved as if the light that has passed through the color separation lens array 130 had been split into two light beams according to wavelength, each beam traveling in a different direction and then being focused.

[0075] In this way, a predetermined propagation distance requirement is determined so that light of that wavelength can be focused onto that photosensitive cell, and the thickness h of the spacer layer 120 can be determined accordingly. The thickness h of the spacer layer 120 also depends on the wavelength λ to be split, the pixel size, and the arrangement pitch p of the photosensitive cells. The thickness h of the spacer layer 120 can be larger than the central wavelength λ of the visible light wavelength band to be split, and can be in the range of 1p to 3p compared with the arrangement pitch p of the photosensitive cells, which is the distance between the centers of adjacent photosensitive cells. More specifically, the thickness h of the spacer layer 120 can be in the range of 500 nm to 5 μm. Details of how to set the thickness h of the spacer layer 120 will be described later with reference to FIGS. 10A to 10E, 11A to 11E, and 12A to 12E.

[0076] 6A and 6B are computer-generated images of the phase distribution of blue light that has passed through the color separation lens array and the focusing distribution of blue light in the photosensitive cells facing the color separation lens array. FIG. 6C exemplarily illustrates a second region of the color separation lens array corresponding to blue pixel B and the traveling direction of blue light that has entered its periphery. FIG. 6D exemplarily illustrates a microlens array that functions equivalently to the color separation lens array with respect to blue light.

[0077] Regarding the phase distribution illustrated in Figure 6A, the phase at the center of the area corresponding to the blue pixel B is approximately 2π, the phase at the center of the area corresponding to the adjacent green pixel G is approximately π, and the phase at the center of the area corresponding to the diagonal red pixel R is approximately a value smaller than π (e.g., approximately 0.2π to 0.7π).

[0078] Such a phase distribution can exhibit a focusing distribution of blue light as shown in Figure 6B, where most of the blue light is focused in the area corresponding to blue pixel B, and almost no blue light reaches the areas corresponding to other pixels.

[0079] As a result, the blue light that is incident on the second region 132 corresponding to the blue pixel B and its periphery passes through the color separation lens array 130 and then travels as shown in Fig. 6C. For example, of the incident light that is incident on the second region 132 of the color separation lens array 130 and part of the other regions surrounding the second region 132, the blue light is focused on the second photosensitive cell 112 immediately below the second region 132. In other words, the following light is incident on one blue pixel B: the blue light from the second region 132 corresponding to that blue pixel B, the blue light from two first regions 131 that are horizontally adjacent to the second region 132, the blue light from two fourth regions 134 that are vertically adjacent to the second region 132, and the blue light from four third regions 133 that are diagonally adjacent to the second region 132.

[0080] 6D , for blue light, the color separation lens array 130 can function equivalently to an array of multiple microlenses ML1 arranged around the second photosensitive cells 112. Since each equivalent microlens ML1 is larger than the corresponding second photosensitive cell 112, it can focus not only the blue light incident on the region of the second photosensitive cell 112 but also the blue light incident on other regions surrounding the second photosensitive cell 112 onto the second photosensitive cell 112. For example, each microlens ML1 is about four times larger than the corresponding second photosensitive cell 112, and the four sides of each microlens ML1 are parallel to the four sides of the second photosensitive cell 112.

[0081] 7A and 7B are computer-generated images of the phase distribution of green light passing through a color separation lens array and the focusing distribution of green light in photosensitive cells facing the color separation lens array. FIG. 7C exemplarily illustrates the first and fourth regions of the color separation lens array corresponding to green pixels and the direction of travel of green light incident on the periphery thereof. FIG. 7D exemplarily illustrates a microlens array that functions equivalently to the color separation lens array with respect to green light.

[0082] Regarding the phase distribution illustrated in Figure 7A, the phase at the center of the area corresponding to the green pixel G is approximately 2π, and the phase at the center of the areas corresponding to the adjacent blue pixel B and red pixel R shows a value of approximately π.

[0083] Such a phase distribution can exhibit a focusing distribution of green light as shown in Figure 7B, where the green light is split and focused in the areas corresponding to the two green pixels G, with almost no green light reaching the areas corresponding to the other pixels.

[0084] As a result, the green light that is incident on the first region 131 and the fourth region 134 corresponding to the green pixel G and on their peripheries passes through the color separation lens array 130 and then travels as shown in Fig. 7C. For example, of the incident light that is incident on the first region 131 of the color separation lens array 130 and parts of the other regions surrounding the first region 131, the green light is focused on the first photosensitive cell 111 located immediately below the first region 131. In other words, the green light coming from the first region 131 or the fourth region 134 corresponding to that green pixel G, and the green light coming from the two second regions 132 and the two third regions 133 that are adjacent to the first region 131 or the fourth region 134 in the horizontal and vertical directions, are incident on one green pixel G.

[0085] 7D , for green light, the color separation lens array 130 can function equivalently to an array of microlenses ML2 arranged around the first and fourth photosensitive cells 111 and 114. Each equivalent microlens ML2 is larger than the corresponding first or fourth photosensitive cell 111 or 114, and can therefore focus not only the green light incident on the region of the first or fourth photosensitive cell 111 or 114, but also the green light incident on other regions surrounding the first or fourth photosensitive cell 111 or 114, onto the first or fourth photosensitive cell 111 or 114. For example, each microlens ML2 is twice as large as the corresponding first or fourth photosensitive cell 111 or 114, and is disposed diagonally adjacent to the corresponding first or fourth photosensitive cell 111 or 114.

[0086] 8A and 8B are computer-generated images of the phase distribution of red light that has passed through the color separation lens array and the focusing distribution of red light in the photosensitive cells facing the color separation lens array. FIG. 8C exemplarily illustrates a third region of the color separation lens array corresponding to a red pixel and the traveling direction of red light that has entered its periphery. FIG. 8D exemplarily illustrates a microlens array that functions equivalently to the color separation lens array with respect to the red pixel R.

[0087] Regarding the phase distribution illustrated in Figure 8A, the phase at the center of the area corresponding to the red pixel R is approximately 2π, the phase at the center of the area corresponding to the adjacent green pixel G is approximately π, and the phase at the center of the area corresponding to the diagonal blue pixel B is approximately a value smaller than π (e.g., approximately 0.2π to 0.7π).

[0088] Such a phase distribution can exhibit a focusing distribution of red light as shown in Fig. 8B, where the red light is focused in the area corresponding to the red pixel R, and almost no red light reaches the areas corresponding to other pixels.

[0089] As a result, light that has entered the third region 133 corresponding to the red pixel R and its periphery passes through the color separation lens array 130 and then travels as shown in Fig. 8C. For example, of the incident light that enters the third region 133 of the color separation lens array 130 and parts of the other regions surrounding the third region 133, red light is focused on the third photosensitive cell 113 immediately below the third region 133. In other words, a single red pixel R is incident with the following light: the red light from the third region 133 corresponding to that red pixel R, the red light from two fourth regions 134 that are horizontally adjacent to the third region 133, the red light from two first regions 131 that are vertically adjacent to the third region 133, and the red light from four second regions 132 that are diagonally adjacent to the third region 133.

[0090] 8D , for red light, the color separation lens array 130 can function equivalently to an array of a plurality of microlenses ML3 arranged around the third photosensitive cell 113. Since each equivalent microlens ML3 is larger than the corresponding third photosensitive cell 113, it can focus not only the red light incident on the region of the third photosensitive cell 113 but also the red light incident on other regions surrounding the third photosensitive cell 113 onto the third photosensitive cell 113. For example, each microlens ML3 is about four times larger than the corresponding third photosensitive cell 113, and the four sides of each microlens ML3 are parallel to the four sides of the third photosensitive cell 113.

[0091] The paths of the blue light, green light, and red light described in FIGS. 6C, 7C, and 8C are such that the light incident on each region is branched according to color, and can be further described as follows.

[0092] 9A exemplarily illustrates the traveling direction of light incident on a region corresponding to a blue pixel B. Referring to FIG. 9A, light L incident on a second region 132 corresponding to a blue pixel B i of blue light L B The incident light L that is incident on the second region 132 travels toward the second photosensitive cell 112 located immediately below the second region 132. iGreen light out of G The incident light L mostly travels to the two first photosensitive cells 111 adjacent to the second photosensitive cell 112 in the horizontal direction and the two fourth photosensitive cells 114 adjacent to the second photosensitive cell 112 in the vertical direction. i Red light L R Most of the light travels to the four third photosensitive cells 113 diagonally adjacent to the second photosensitive cell 112.

[0093] 9B shows an example of the traveling direction of light incident on a region corresponding to a green pixel G. Referring to FIG. 9B, light L incident on a first region 131 corresponding to a green pixel G i Green light out of G The light L incident on the first region 131 travels toward the first photosensitive cell 111 located immediately below the first region 131. i of blue light L B The red light L R 1 travels mostly toward the two third photosensitive cells 113 that are vertically adjacent to the first photosensitive cell 111.

[0094] 9C shows an example of the direction of travel of light incident on a region corresponding to a red pixel R. Light L incident on the third region 133 corresponding to a red pixel R i Red light L R The incident light L that is incident on the third region 133 travels toward the third photosensitive cell 113 located immediately below the third region 133. i Green light out of G The incident light L travels toward the two first photosensitive cells 111 adjacent to the third photosensitive cell 113 in the vertical direction and the two fourth photosensitive cells 114 adjacent to the third photosensitive cell 113 in the horizontal direction. i of blue light L B 1 travels mostly toward the four second photosensitive cells 112 diagonally adjacent to the third photosensitive cell 113.

[0095] Such color separation and light collection can be achieved more effectively by appropriately setting the thickness of the spacer layer 120. For example, when the theoretical thickness h tcan satisfy the following Equation 1, where n is the refractive index of the spacer layer 120 associated with the wavelength λ0 and p is the pitch of the photosensitive cells.

[0096]

number

[0097] Here, the theoretical thickness h of the spacer layer 120 t means the focal length at which light having a wavelength of λ is focused by the color separation lens array 130 onto the upper surfaces of the photosensitive cells 111, 112, 113, and 114. In other words, while passing through the color separation lens array 130, light having a wavelength of λ is focused from the lower surface of the color separation lens array 130 at a focal length of h t It also focuses at relatively far distances.

[0098] As described in Equation 1, the theoretical thickness h of the spacer layer 120 t also depends on the pitch p of the photosensitive cells 111, 112, 113, and 114 and the refractive index n of the spacer layer 120. For example, if we assume that the central wavelength λ0 of the visible light band is 540 nm, the pitch p of the photosensitive cells 111, 112, 113, and 114 is 0.8 μm, and the refractive index n of the spacer layer 120 at a wavelength of 540 nm is 1.46, then the theoretical thickness h of the spacer layer 120 will be t In other words, the optimum distance between the lower surface of the color separation lens array 130 and the upper surface of the sensor substrate 110 is also about 1.64 μm. However, the actual thickness of the spacer layer 120 is smaller than the theoretical thickness h t For example, in consideration of the efficiency of the color separation lens array 130, the theoretical thickness h t Based on this, the actual thickness of the spacer layer 120 can be selected within a predetermined range.

[0099] 10A to 10E are graphs illustrating an example of how the efficiency of the color separation lens array 130 changes depending on the distance between the color separation lens array 130 and the sensor substrate 110 when the pitch of the photosensitive cells 111, 112, 113, and 114 is 0.7 μm. FIG. 10A shows the light-collecting efficiency of the color separation lens array 130 with respect to blue light incident on the second photosensitive cell 112 from the first region 131 to the fourth region 134 constituting the unit pattern array of the color separation lens array 130. FIG. 10B shows the light-collecting efficiency of the color separation lens array 130 with respect to green light incident on the first photosensitive cell 111 and the fourth photosensitive cell 114 from the first region 131 to the fourth region 134 constituting the unit pattern array. FIG. 10C shows the light-collecting efficiency of the color separation lens array 130 with respect to red light incident on the third photosensitive cell 113 from the first region 131 to the fourth region 134 constituting the unit pattern array.

[0100] 10A and 10C, four regions are arranged for one photosensitive cell, so the theoretical maximum is 4. In FIG. 10B, four regions are arranged for two photosensitive cells, so the theoretical maximum is 2. In the graphs of FIGS. 10A to 10C, the distance at which the light-collecting efficiency of the color separation lens array 130 is at the theoretical thickness h that satisfies Equation 1 is t As shown in Figures 10A to 10C, the theoretical thickness h t varies slightly depending on the wavelength.

[0101] FIG. 10D is a graph showing an example of the change in efficiency of a color separation lens array taking into account the sensitivity characteristics of the human eye to visible light. For example, the human eye is generally most sensitive to green light and least sensitive to blue light. Therefore, the graph of FIG. 10D can be obtained by assigning the lowest weight to the graph of FIG. 10A, a weight higher than blue light to the graph of FIG. 10C, and a weight higher than blue light to the graph of FIG. 10B, and then averaging the summed values. FIG. 10E is a graph showing the results of normalizing the graph of FIG. 10D.

[0102] 10D and 10E, when the pitch of the photosensitive cells 111, 112, 113, and 114 is 0.7 μm, the efficiency of the color separation lens array 130 with respect to the entire visible light spectrum, taking into account the sensitivity characteristics of the human eye, is highest at a distance of about 1.2 μm. Also, the efficiency of the color separation lens array 130 is about 80% of its maximum efficiency at a distance of about 0.5 μm, and about 95% of its maximum efficiency at a distance of about 1.9 μm.

[0103] 11A to 11E are graphs illustrating an example of how the efficiency of the color separation lens array 130 varies with the distance between the color separation lens array 130 and the sensor substrate 110 when the pitch of the photosensitive cells 111, 112, 113, and 114 is 0.8 μm. Referring to Figures 11A to 11E, when the pitch of the photosensitive cells 111, 112, 113, and 114 is 0.8 μm, the efficiency of the color separation lens array 130 with respect to all visible light rays, taking into account the sensitivity characteristics of the human eye, is highest at a distance of about 1.64 μm. Furthermore, the efficiency of the color separation lens array 130 is approximately 85% of its maximum efficiency at a distance of about 0.8 μm, and approximately 93% of its maximum efficiency at a distance of about 2.5 μm.

[0104] 12A to 12E are graphs illustrating an example of how the efficiency of the color separation lens array 130 varies with the distance between the color separation lens array 130 and the sensor substrate 110 when the pitch of the photosensitive cells 111, 112, 113, and 114 is 1.0 μm. Referring to Figures 12A to 12E, when the pitch of the photosensitive cells 111, 112, 113, and 114 is 1.0 μm, the efficiency of the color separation lens array 130 with respect to all visible light rays, taking into account the sensitivity characteristics of the human eye, is highest at a distance of about 2.6 μm. Furthermore, the efficiency of the color separation lens array 130 is approximately 87% of its maximum efficiency at a distance of about 1.6 μm, and approximately 94% of its maximum efficiency at a distance of about 3.6 μm.

[0105] As a result, the actual thickness h of the spacer layer 120 is less than the theoretical thickness h of Equation 1. tIt can be seen that the color separation lens array 130 has a high efficiency of 80% or more, 90% or more, or even 95% or more of the maximum efficiency, even if the pitch p of the photosensitive cells 111, 112, 113, and 114 is larger or smaller than the pitch p. Considering the above results, the actual thickness h of the spacer layer 120 is h t -p≦h≦h t It is also selected within the range of +p.

[0106] The color separation lens array 130 described above can split incident light into wavelengths without absorbing or blocking it and focus the split light on specific areas, thereby improving the light utilization efficiency of the image sensor. Furthermore, because the color separation lens array 130 has improved color separation performance, an image sensor employing the color separation lens array 130 can have excellent color purity. Furthermore, an image sensor employing the color separation lens array 130 can maintain the Bayer pattern method commonly adopted in image sensors and utilize the same image processing algorithm as an existing pixel structure. Furthermore, because the color separation lens array 130 can also function as a lens that focuses incident light, an image sensor employing the color separation lens array 130 does not require a separate microlens to focus light on each pixel.

[0107] 13 is a perspective view showing an exemplary shape of a nanopost that may also be used in a color separation lens array according to an embodiment. Referring to FIG. 13, the nanopost may have a cylindrical shape with a diameter D and a height H. The diameter D and / or height H may have sub-wavelength values, and the diameter D may vary depending on the location where the nanopost is disposed.

[0108] The nanoposts can also be formed into pillars with various cross-sectional shapes. Figures 14A through 14H are plan views showing exemplary shapes of nanoposts that can be employed in the color separation lens array 130 of the image sensor.

[0109] The cross-sectional shape of the nanopost may be a circular ring shape with an outer diameter D and an inner diameter Di, as shown in FIG. 14A. The ring width w may have a subwavelength value. The cross-sectional shape of the nanopost may be an ellipse shape with a major axis length Dx and a minor axis length Dy that are different in the first direction (X direction) and the second direction (Y direction), as shown in FIG. 14B. Such a shape is also adopted for the first region 131 and the fourth region 134 corresponding to the green pixel, as mentioned when explaining the embodiment of FIG. 5B.

[0110] Furthermore, the cross-sectional shape of the nanopost may be a square, a square ring, or a cross, as shown in Figures 14C, 14D, and 14F, or a rectangle or cross, with different lengths Dx and Dy in the first direction (X direction) and the second direction (Y direction), as shown in Figures 14E and 14G. Such a rectangular or cross shape is also employed for the first region 131 and the fourth region 134 corresponding to the green pixel, as mentioned in the description of the embodiment of Figure 5B.

[0111] As yet another example, the cross-sectional shape of the nanopost can have multiple concave arcs, as shown in Figure 14H.

[0112] FIG. 15 is a plan view illustrating an example of an arrangement of nanoposts forming a color separation lens array according to another embodiment.

[0113] The color separation lens array 140 may have a configuration corresponding to the Bayer pattern pixel arrangement illustrated in FIG. 2A and may include a region divided into four: a first region 141 corresponding to a green pixel G, a second region 142 corresponding to a blue pixel B, a third region 143 corresponding to a red pixel R, and a fourth region 144 corresponding to a green pixel G. Although not shown, such unit pattern arrays may be arranged repeatedly along the first direction (X direction) and the second direction (Y direction). Each region may be equally divided into multiple subregions, and nanopost NPs may be arranged at the intersections of the subregion boundaries. FIG. 15 shows an example with nine subregions, where nanopost NPs are arranged on the lattice points dividing the nine subregions. Each of the regions 141, 142, 143, and 144 has no nanopost NPs in the center, but has four nanopost NPs of the same size at its center. The nanopost NPs at the periphery are arranged on the boundary lines between the other regions. The nanoposts NPs are labeled r1 to r9 according to their detailed positions within the unit pattern array.

[0114] 15, nanopost r1 disposed at the center of first region 141 corresponding to a green pixel has a larger cross-sectional area than nanoposts r5, r6, and r9 disposed at the periphery, and nanopost r4 disposed at the center of fourth region 144 corresponding to a green pixel also has a larger cross-sectional area than nanoposts r7, r8, and r9 disposed at the periphery. The cross-sectional areas of nanoposts r1 and r4 disposed at the centers of first region 141 and fourth region 144 corresponding to a green pixel are also larger than the cross-sectional areas of nanopost r2 disposed at the center of second region 142 corresponding to a blue pixel and nanopost r3 disposed at the center of third region 143 corresponding to a red pixel. The cross-sectional area of ​​nanopost r2 disposed at the center of second region 142 corresponding to a blue pixel is also larger than the cross-sectional area of ​​nanopost r3 disposed at the center of third region 143 corresponding to a red pixel.

[0115] The nanopost NPs in the second region 142 and the third region 143 are also arranged symmetrically along the first direction (X direction) and the second direction (Y direction), and the nanopost NPs in the first region 141 and the fourth region 144 are also arranged asymmetrically along the first direction (X direction) and the second direction (Y direction). In other words, the nanopost NPs in the second region 142 and the third region 143 corresponding to blue and red pixels, respectively, may have the same distribution pattern along the first direction (X direction) and the second direction (Y direction), and the nanopost NPs in the first region 141 and the fourth region 144 corresponding to green pixels may have different distribution patterns along the first direction (X direction) and the second direction (Y direction).

[0116] Among the nanoposts NP, the cross-sectional area of ​​nanopost r5 located at the boundary between the first region 141 and the second region 142 adjacent thereto in the first direction (X direction) is different from the cross-sectional area of ​​nanopost r6 located at the boundary between the first region 141 and the third region 143 adjacent thereto in the second direction (Y direction).Furthermore, the cross-sectional area of ​​nanopost r7 located at the boundary between the fourth region 144 and the third region 143 adjacent thereto in the first direction (X direction) is different from the cross-sectional area of ​​nanopost r8 located at the boundary between the fourth region 144 and the second region 142 adjacent thereto in the second direction (Y direction).

[0117] On the other hand, the cross-sectional area of ​​nanopost r5 located at the boundary between the first region 141 and the second region 142 adjacent to it in the first direction (X direction) is the same as the cross-sectional area of ​​nanopost r8 located at the boundary between the fourth region 144 and the second region 142 adjacent to it in the second direction (Y direction), and the cross-sectional area of ​​nanopost r6 located at the boundary between the first region 141 and the third region 143 adjacent to it in the second direction (Y direction) is the same as the cross-sectional area of ​​nanopost r7 located at the boundary between the fourth region 144 and the third region 143 adjacent to it in the first direction (X direction).

[0118] On the other hand, the nanoposts r9 arranged at the corners of the first region 141, the second region 142, the third region 143, and the fourth region 144, that is, at the positions where the four regions intersect, have the same cross-sectional area.

[0119] In this way, the nanoposts NPs are arranged in a four-fold symmetrical form in the second region 142 and the third region 143 corresponding to the blue pixel and the red pixel, respectively, and the nanoposts NPs are arranged in a two-fold symmetrical form in the first and fourth regions 141 and 144 corresponding to the green pixel, with the first region 141 and the fourth region 144 rotated by 90° with respect to each other. Such a form is also shown in the embodiments of Figures 16 and 17 described below.

[0120] FIG. 16 is a plan view illustrating an exemplary arrangement of nanoposts forming a color separation lens array according to yet another embodiment.

[0121] The color separation lens array 150 has a shape corresponding to a Bayer pattern pixel array and may include a region divided into four regions: a first region 151 corresponding to green pixels, a second region 152 corresponding to blue pixels, a third region 153 corresponding to red pixels, and a fourth region 154 corresponding to green pixels. Each region may be equally divided into a plurality of subregions, and nanoposts NPs may be disposed at the intersections of the subregion boundaries. FIG. 16 differs from the nanopost array of FIG. 15 in that it shows an example with 16 subregions. Nanoposts NPs are disposed on lattice points dividing the subregions into 16, with nanoposts NPs disposed in the center of each region 151, 152, 153, and 154. The nanoposts NPs are labeled s1 to s11 according to their precise positions within the unit pattern array.

[0122] In the embodiment of Figure 16, the nanopost s1 located in the center of the first region 151 corresponding to the green pixel and the nanopost s4 located in the center of the fourth region 154 not only have a larger cross-sectional area than the nanoposts NP located in the peripheral areas, but also have a larger cross-sectional area than the nanoposts NP located in the second region 152 corresponding to the blue pixel and the third region 153 corresponding to the red pixel.

[0123] In the first region 151, nanopost s1, which has the largest cross-sectional area, is arranged in the center, followed by nanoposts s10, s5, and s6, whose cross-sectional areas gradually decrease toward the periphery. Similarly, in the fourth region 154, nanopost s4, which has the largest cross-sectional area, is arranged in the center, followed by nanoposts s11, s7, and s8, whose cross-sectional areas gradually decrease toward the periphery. In contrast, in the second region 152, nine nanoposts s2, each with the same cross-sectional area, are arranged in the center, followed by nanoposts s5 and s8, each with a larger cross-sectional area, located on the periphery. Similarly, in the third region 153, nine nanoposts s3, each with the same cross-sectional area, are arranged in the center, followed by nanoposts s6 and s7, each with a larger cross-sectional area, located on the periphery. In both the second region 152 and the third region 153, the nanoposts NP in the periphery are arranged on the boundary lines with the other regions.

[0124] 15, in the embodiment of Fig. 16, the nanoposts NP in the second region 152 and the third region 153 are also arranged symmetrically along the first direction (X direction) and the second direction (Y direction), and the nanoposts NP in the first region 151 and the fourth region 154 are also arranged asymmetrically along the first direction (X direction) and the second direction (Y direction). Furthermore, the nanoposts s9 arranged at the corners of the first region 151, the second region 152, the third region 153, and the fourth region 154, i.e., at positions where the four regions are adjacent, have the same cross-sectional area.

[0125] FIG. 17 is a plan view illustrating an exemplary arrangement of nanoposts forming a color separation lens array according to yet another embodiment.

[0126] The color separation lens array 160 has a shape corresponding to a Bayer pattern pixel arrangement and may include a region divided into four regions: a first region 161 corresponding to green pixels, a second region 162 corresponding to blue pixels, a third region 163 corresponding to red pixels, and a fourth region 164 corresponding to green pixels. Each region is also divided into a plurality of subregions, and nanopost NPs may be arranged within the subregions. The color separation lens array 160 is similar to FIG. 15 in that each region is divided into nine subregions, but differs in that the nanopost NPs are arranged inside the subregions, not at their intersections. The nanopost NPs are labeled t1 to t16 according to their precise positions within the unit pattern array.

[0127] 17, the nanopost t1 located at the center of the first region 161 and the nanopost t4 located at the center of the fourth region 164 have larger cross-sectional areas than not only the nanoposts NP located in their peripheral areas but also the nanoposts NP located in the second region 162 and the third region 163. The cross-sectional area of ​​the nanopost t2 located at the center of the second region 162 is also larger than the cross-sectional area of ​​the nanopost t3 located at the center of the third region 163. In the case of the second region 162, the cross-sectional areas of the nanoposts t6 and t10 located at the periphery separated from the center in the first direction (X direction) and the second direction (Y direction) are larger than the cross-sectional area of ​​the central nanopost t2. In contrast, the cross-sectional area of ​​the nanopost t14 located at the periphery separated from the center in the diagonal direction is smaller than the cross-sectional area of ​​the central nanopost t2. In the third region 163, the central nanopost t3 has the smallest cross-sectional area, and the peripheral nanoposts t7, t11, and t15 all have cross-sectional areas larger than the central nanopost t3.

[0128] The nanopost NPs in the second region 162 and the third region 163 are also arranged symmetrically along the first direction (X direction) and the second direction (Y direction), while the nanopost NPs in the first region 161 and the fourth region 164 are also arranged asymmetrically along the first direction (X direction) and the second direction (Y direction). In other words, the nanopost NPs in the second region 162 and the third region 163 corresponding to blue and red pixels, respectively, exhibit the same distribution pattern along the first direction (X direction) and the second direction (Y direction), while the nanopost NPs in the first region 161 and the fourth region 164 corresponding to green pixels exhibit different distribution patterns along the first direction (X direction) and the second direction (Y direction).

[0129] In the first region 161, the central nanopost t1, the nanopost t5 adjacent to it in the first direction (X direction), and the nanopost t9 adjacent to it in the second direction (Y direction) have different cross-sectional areas. Similarly, in the fourth region 164, the central nanopost t4, the nanopost t8 adjacent to it in the first direction (X direction), and the nanopost t12 adjacent to it in the second direction (Y direction) have different cross-sectional areas. In this case, the nanopost t1 at the center of the first region 161 and the nanopost t5 adjacent to it in the first direction (X direction), the nanopost t4 at the center of the fourth region 164 and the nanopost t12 adjacent to it in the second direction (Y direction) have the same cross-sectional area, and the nanopost t1 at the center of the first region 161 and the nanopost t9 adjacent to it in the second direction (Y direction), the nanopost t4 at the center of the fourth region 164 and the nanopost t8 adjacent to it in the first direction (X direction) have the same cross-sectional area. The nanopost t13 located adjacent to the corner of the first region 161 and the nanopost t16 located adjacent to the corner of the fourth region 164 have the same cross-sectional area. In this way, the first region 161 and the fourth region 164 are rotated 90° relative to each other.

[0130] The nanopost t2 at the center of the second region 162, the nanopost t6 adjacent to it in the first direction (X direction), and the nanopost t10 adjacent to it in the second direction (Y direction) all have the same cross-sectional area. The nanopost t14 located adjacent to a corner of the second region 162 also has the same cross-sectional area.

[0131] In the third region 163, the central nanopost t3, the nanopost t7 adjacent to it in the first direction (X direction), and the nanopost t11 ​​adjacent to it in the second direction (Y direction) all have the same cross-sectional area. The nanopost t15 located adjacent to the corner of the third region 163 also has the same cross-sectional area.

[0132] FIG. 18 is a plan view illustrating an exemplary arrangement of a plurality of nanoposts forming a color separation lens array according to yet another embodiment.

[0133] 18 is an embodiment with the simplest structure. One nanopost NP is arranged in each of a first region 171 corresponding to a green pixel, a second region 172 corresponding to a blue pixel, a third region 173 corresponding to a red pixel, and a fourth region 174 corresponding to a green pixel. The cross-sectional areas of the nanopost NPs in the first region 171 and the fourth region 174 are the largest, the cross-sectional area of ​​the nanopost NPs in the second region 172 is smaller than the cross-sectional area of ​​the nanopost NPs in the first region 171, and the cross-sectional area of ​​the nanopost NPs in the third region 173 is the smallest.

[0134] FIG. 19 is a graph showing an example of the spectral distribution of light incident on each of the red, green, and blue pixels R, G, and B of the image sensor including the color separation lens array of FIG.

[0135] 20A and 20B are cross-sectional views showing a schematic structure of a pixel array according to another embodiment, each taken along a different cross section. The pixel array 1100a differs from the embodiment shown in FIGS. 4A and 4B in that a color filter 105 is further disposed between the sensor substrate 110 and the color separation lens array 130. The color filter 105 is also disposed between the sensor substrate 110 and the spacer layer 120.

[0136] The pixel array 1100a may further include a transparent dielectric layer 121 that protects the color separation lens array 130. The dielectric layer 121 is also disposed to cover the spaces between adjacent nanopost NPs and the top surfaces of the nanopost NPs. The dielectric layer 121 may be made of a material having a refractive index lower than that of the nanopost NPs, for example, the same material as the spacer layer 120.

[0137] The color filter 105 has filter regions whose shape corresponds to the pixel arrangement of the Bayer pattern. As shown in FIG. 20A , green filter regions CF1 and blue filter regions CF2 are alternately arranged, and as shown in FIG. 20B , red filter regions CF3 and green filter regions CF1 are alternately arranged in rows spaced apart in the Y direction. The color filter 105 is not an essential component, since the color separation lens array 130 splits and focuses light of different wavelengths onto the multiple photosensitive cells 111, 112, 113, and 114. However, the additional color filter 105 complements color purity, and since substantially color-separated light enters the color filter 105, light loss is not significant.

[0138] 21 and 22 are graphs showing exemplary spectral distributions of light incident on the red pixel R, green pixel G, and blue pixel B of an image sensor, respectively showing the spectral distributions of an embodiment with a color filter and an embodiment without a color filter.

[0139] The graph in Figure 21 shows the spectrum of the image sensor equipped with the color filters shown in Figures 20A and 20B, and the graph in Figure 22 shows the spectrum of the image sensor without the color filters shown in Figures 4A and 4B. Figures 21 and 22 show the simulation results of an image sensor with a pixel width of about 0.7 μm, and although the overall light intensity tends to be lower when color filters are provided, both show good color separation performance.

[0140] FIG. 23 is a plan view illustrating a color separation lens array according to another embodiment. Referring to FIG. 23, a color separation lens array 340 may include a number of unit pattern arrays indicated by thick lines. Each unit pattern array is arranged in a two-dimensional 2×2 configuration including a first region 341, a second region 342, a third region 343, and a fourth region 344. Looking at the overall configuration of the color separation lens array 340, the first regions 341 and the second regions 342 are alternately arranged in the horizontal direction within one row, and the third regions 343 and the fourth regions 344 are alternately arranged in the horizontal direction within another row. Furthermore, the first regions 341 and the third regions 343 are alternately arranged in the vertical direction within one column, and a number of second regions 342 and a number of fourth regions 344 are alternately arranged in the vertical direction within another column.

[0141] The color separation lens array 340 may further include a plurality of first regions 341 to fourth regions 344 that do not belong to any unit pattern array. The first regions 341 to fourth regions 344 that do not belong to any unit pattern array may also be arranged along the edge of the color separation lens array 340. In other words, a plurality of second regions 342 and a plurality of fourth regions 344 may be additionally arranged in a column on the left edge of the color separation lens array 340, a plurality of first regions 341 and a plurality of third regions 343 may be additionally arranged in a column on the right edge, a plurality of third regions 343 and a plurality of fourth regions 344 may be additionally arranged in a row on the upper edge, and a plurality of first regions 341 and a plurality of second regions 342 may be additionally arranged in a row on the lower edge.

[0142] Fig. 24 is a vertical cross-section of the color separation lens array 340 shown in Fig. 23 taken along line CC'. Referring to Fig. 24, the color separation lens array 340 may include a plurality of first regions 341 and a plurality of second regions 342, each of which is arranged to protrude horizontally from the edge of the sensor substrate 110 and does not face any photosensitive cells of the sensor substrate 110 in the vertical direction. Although not shown in Fig. 24, the plurality of first regions 341 to fourth regions 344, which do not belong to any unit pattern array in Fig. 23, are all arranged to protrude horizontally from the edge of the sensor substrate 110 and do not face any photosensitive cells in the vertical direction.

[0143] As illustrated in FIGS. 6A to 6D, 7A to 7D, and 8A to 8D, each photosensitive cell receives light not only from the vertically corresponding region of the color separation lens array 340 but also from multiple other regions located around that region. Therefore, without the first to fourth regions 341 to 344 added along the edges of the color separation lens array 340, the amount of light incident on the photosensitive cells arranged along the edges of the sensor substrate 110 would be reduced, resulting in a decrease in color purity. By adding the first to fourth regions 341 to 344 along the edges of the color separation lens array 340, light can be provided to the photosensitive cells arranged along the edges of the sensor substrate 110 in the same way as the photosensitive cells arranged inside the sensor substrate 110. The embodiments illustrated in FIGS. 23 and 24 may also be applied to the color separation lens arrays 130, 140, 150, 160, and 170 described above.

[0144] FIG. 25 is a cross-sectional view showing a schematic structure of a pixel array according to yet another embodiment, and FIG. 26 is a perspective view showing an exemplary shape of nanoposts employed in the color separation lens array of FIG.

[0145] The pixel array 1100b includes a sensor substrate 310 that senses light and a color separation lens array 350 that is disposed on the sensor substrate 310. A spacer layer 320 is disposed between the sensor substrate 310 and the color separation lens array 350. The color separation lens array 350 is supported by the spacer layer 320 and includes a plurality of nanoposts NPs that are arranged according to a predetermined pattern. The sensor substrate 310 includes a plurality of photosensitive cells that sense light and can face a plurality of regions of the color separation lens array 350 in one-to-one correspondence. The illustration of such region divisions is omitted for convenience.

[0146] The color separation lens array 350 according to this embodiment differs from the previous embodiment in that each of the plurality of nanoposts NP includes a lower post LP and an upper post UP stacked on the lower post LP.

[0147] Some of the nanoposts NP may have a stacked shape in which the lower posts LP and the upper posts UP are misaligned with each other. The degree of misalignment is indicated by b in FIG. 26, and the magnitude of the misalignment increases from the center C toward the periphery p of the pixel array 1100b, i.e., along the radial direction. The direction in which the upper posts UP are misaligned from the lower posts LP is from the center C toward the periphery p.

[0148] To fabricate nanoposts NP with such a structure, a first material layer 331 that fills the regions between the lower posts LP and supports the upper posts UP, and a second material layer 332 that covers the upper posts UP may be further provided. The first material layer 331 and the second material layer 332 may be formed of a material with a refractive index lower than that of the material forming the upper posts UP and the lower posts LP.

[0149] This arrangement takes into consideration the difference in the angle of incidence of light between the periphery and the center of the pixel array 1100b used in the imaging device. Generally, light is incident perpendicularly near the center C of the pixel array 1100b, and the angle of incidence increases toward the periphery p. By configuring the nanopost NPs in a form corresponding to this incidence path, it is possible to more effectively achieve the color separation intended by the nanopost NPs, even for oblique light rays that are obliquely incident on the pixel array 1100b.

[0150] Although the nanopost NPs are illustrated as having a two-layer structure, they may also have a three-layer structure or more, and the shape and size of the nanoposts in the two layers may vary depending on the position. The embodiments shown in Figures 25 and 26 may also be applied to the color separation lens arrays 130, 140, 150, 160, 170, and 340 described above.

[0151] The image sensors according to the above-described embodiments can provide a sufficient amount of light to pixels even when the pixel size is small because there is almost no light loss due to color filters. Therefore, it is possible to fabricate ultra-high-resolution, micro-sensitive image sensors having hundreds of millions of pixels. Such ultra-high-resolution, micro-sensitive image sensors can also be used in a variety of high-performance optical or electronic devices. Such electronic devices include, but are not limited to, smartphones, mobile phones, personal digital assistants (PDAs), laptops, personal computers (PCs), various portable devices, home appliances, security cameras, medical cameras, automobiles, Internet of Things (IoT) devices, and other mobile or non-mobile computing devices.

[0152] 27 is a block diagram illustrating an electronic device including an image sensor according to an embodiment. The electronic device includes an image sensor 1000, a processor 2200, a memory 2300, a display 2400, and a bus 2500. The image sensor 1000 acquires image information related to an external object under the control of the processor 2200 and provides the image information to the processor 2200. The processor 2200 can store the image information provided from the image sensor 1000 in the memory 2300 via the bus 2500 and output the image information stored in the memory 2300 to the display 2400 for display to a user. The processor 2200 can also perform various image processing on the image information provided from the image sensor 1000.

[0153] 28 to 38 show various multimedia examples of electronic devices to which an image sensor according to an embodiment is applied.

[0154] The image sensor according to an embodiment can be applied to various multimedia devices having a video capture function. For example, the image sensor can be applied to a camera 2000 shown in Fig. 28. The camera 2000 can be a digital camera or a digital camcorder.

[0155] Referring to FIG. 29, a camera 2000 may include an imaging unit 2100, an image sensor 1000, and a processor 2200.

[0156] The imaging unit 2100 focuses light reflected from the object OBJ to form an optical image. The imaging unit 2100 may include an objective lens 2010, a lens driver 2120, an aperture 2130, and an aperture driver 2140. For convenience, only one lens is shown in FIG. 29 ; however, in reality, the objective lens 2010 may include multiple lenses of different sizes and shapes. The lens driver 2120 may communicate information related to focus detection with the processor 2200 and adjust the position of the objective lens 2010 in response to a control signal provided by the processor 2200. The lens driver 2120 may move the objective lens 2010 to adjust the distance between the objective lens 2010 and the object OBJ or adjust the position of each lens within the objective lens 2010. The lens driver 2120 may drive the objective lens 2010 to adjust the focus on the object OBJ. Such a camera 2000 may be equipped with an auto focus (AF) function.

[0157] The aperture driver 2140 can communicate information related to the amount of light with the processor 2200 and adjust the aperture 2130 according to a control signal provided by the processor 2200. For example, the aperture driver 2140 can increase or decrease the diameter of the aperture 2130 and adjust the opening time of the aperture 2130 according to the amount of light entering the camera 2000 through the objective lens 2010.

[0158] The image sensor 1000 can generate an electrical image signal based on the intensity of incident light. The image sensor 1000 may include a pixel array 1100, a timing controller (T / C) 1010, and an output circuit 1030. Although not shown in FIG. 29, the image sensor 1000 may further include a row decoder as shown in FIG. 1. Light passing through the objective lens 2010 and the aperture 2130 can form an image of an object OBJ on the light-receiving surface of the pixel array 1100. The pixel array 1100 may be a CCD or CMOS that converts optical signals into electrical signals. The pixel array 1100 may include additional pixels for performing an autofocus (AF) function or a distance measurement function. The pixel array 1100 may also include the color separation lens array described above.

[0159] The processor 2200 may control the overall operation of the camera 2000 and may have an image processing function. For example, the processor 2200 may provide control signals for the operation of each component to the lens driver 2120, the aperture driver 2140, the timing controller 1010, etc.

[0160] An image sensor according to an embodiment may also be applied to a mobile phone or smartphone 3000 shown in FIG. 30, a tablet or smart tablet 3100 shown in FIG. 31, a laptop computer 3200 shown in FIG. 32, or a television or smart TV 3300 shown in FIG. 33. For example, the smartphone 3000 or the smart tablet 3100 may include multiple high-resolution cameras, each equipped with a high-resolution image sensor. The high-resolution cameras may be used to extract depth information of an object in an image, adjust out-of-focus of the image, or automatically identify an object in the image.

[0161] Image sensors are also applied to the smart refrigerator 3400 shown in FIG. 34, the security camera 3500 shown in FIG. 35, the robot 3600 shown in FIG. 36, and the medical camera 3700 shown in FIG. 35. For example, the smart refrigerator 3400 can automatically recognize food and beverages in the refrigerator using an image sensor and notify the user via a smartphone of the presence or absence of specific food and beverages, the type of food and beverages that have been taken in, and other information. The security camera 3500 can provide ultra-high-resolution images and utilizes high sensitivity to recognize objects or people in images even in dark environments. The robot 3600 can be deployed in disaster sites or industrial sites where people cannot directly approach and can provide high-resolution images. The medical camera 3700 can provide high-resolution images for diagnosis or surgery and dynamically adjust its field of view.

[0162] The image sensor may also be applied to a vehicle 3800, as shown in Fig. 38. The vehicle 3800 may include a plurality of vehicle cameras 3810, 3820, 3830, and 3840 arranged at various positions. Each of the vehicle cameras 3810, 3820, 3830, and 3840 may include an image sensor according to an embodiment. The vehicle 3800 may provide the driver with various information related to the interior or surroundings of the vehicle 3800 by using the plurality of vehicle cameras 3810, 3820, 3830, and 3840, and may automatically recognize objects or people in the image and provide information necessary for autonomous driving.

[0163] Although the image sensor having the color separation lens array and the electronic device including the same have been described with reference to the embodiments shown in the drawings, these are merely examples, and those skilled in the art will understand that various modifications and equivalent embodiments are possible. Therefore, the disclosed embodiments should be considered from an illustrative rather than a restrictive perspective. The scope of the claims is defined in the appended claims, not the foregoing description, and all differences that fall within the range of equivalents thereof should be construed as being within the scope of the claims. [Explanation of symbols]

[0164] 105 Color Filter 110 Sensor board 111, 112, 113, 114 Photosensitive cells 120 spacer layer 130, 140, 150, 160, 170, 340, 350 Color Separation Lens Array 131, 141, 151, 161, 171 1st area 132, 142, 152, 162, 172 2nd area 133, 143, 153, 163, 173 Third area 134, 144, 154, 164, 174 4th area 1000 image sensors 1010 Timing Controller 1020 Row Decoder 1030 Output circuit 1100, 1100a, 1100b pixel array NP nanopost

Claims

1. a sensor substrate including first and second photosensitive cells that detect light; and a color separation lens array including a first region facing the first photosensitive cells and including first nanoposts, and a second region facing the second photosensitive cells and including second nanoposts, The first nanoposts and the second nanoposts are different from each other in at least one of shape, size, and arrangement; the first nanoposts and the second nanoposts split light having a first wavelength and light having a second wavelength, which are different from each other, from the light incident on the color separation lens array into light beams in different directions, and form phase distributions at positions where the light beams pass through the first region and the second region and are focused on the first photosensitive cell and the second photosensitive cell, respectively; the color separation lens array functions equivalently to an array of a plurality of microlenses for the light of the second wavelength, and each microlens is larger than the second photosensitive cell; the color separation lens array functions equivalently to an array of a plurality of microlenses for the light of the first wavelength, and each microlens is larger than the first photosensitive cell; The first nanopost and the second nanopost are the light of the first wavelength forms a phase distribution of 2Nπ at a position corresponding to a center of the first photosensitive cell immediately after passing through the color separation lens array, and forms a phase distribution of (2N−1)π at a position corresponding to a center of the second photosensitive cell, where N is an integer greater than 0.

2. The first nanopost and the second nanopost are 2. The image sensor of claim 1, wherein, immediately after passing through the color separation lens array, the light of the second wavelength forms a phase distribution of (2M−1)π at a position corresponding to a center of the first photosensitive cell, and forms a phase distribution of 2Mπ at a position corresponding to a center of the second photosensitive cell, where M is an integer greater than 0.

3. The image sensor according to claim 1 , further comprising a spacer layer disposed between the sensor substrate and the color separation lens array, forming a distance between the sensor substrate and the color separation lens array.

4. The image sensor of claim 3 , wherein the spacer layer has a thickness corresponding to a focal length of the color separation lens array at a center wavelength of a wavelength band of incident light that is color-separated by the color separation lens array.

5. The theoretical thickness of the spacer layer is h ｔ , the pitch of the photosensitive cells is p, the refractive index of the spacer layer is n, and the central wavelength of the wavelength band of light that is color-separated by the color separation lens array is λ. ０ Then, the theoretical thickness h of the spacer layer ｔ teeth, [Equation 1] and The actual thickness h of the spacer layer is h ｔ −p≦h≦h ｔ 4. The image sensor of claim 3, wherein:

6. the sensor substrate further includes a third photo-sensitive cell and a fourth photo-sensitive cell that sense light, the color separation lens array includes a third region facing the third photosensitive cell and including third nanoposts, and a fourth region facing the fourth photosensitive cell and including fourth nanoposts; 6. The image sensor of claim 1, wherein the third nanoposts and the fourth nanoposts are different from each other in at least one of shape, size, and arrangement.

7. 7. The image sensor of claim 6, wherein the first to fourth nanoposts split light beams of different first, second, and third wavelengths, which are incident on the color separation lens array, into different directions, and form a phase distribution at a position where the light beams pass through the first to fourth regions, such that the light beams of the first wavelength are focused on the first and fourth photosensitive cells, the light beams of the second wavelength are focused on the second photosensitive cells, and the light beams of the third wavelength are focused on the third photosensitive cells.

8. 8. The image sensor of claim 7, wherein the first wavelength is green light, the second wavelength is blue light, and the third wavelength is red light.

9. The first nanopost to the fourth nanopost are 7. The image sensor according to claim 6, wherein, immediately after passing through the color separation lens array, the light of the first wavelength forms a phase distribution of 2Nπ at positions corresponding to the central parts of the first photosensitive cells and the fourth photosensitive cells, and forms a phase distribution of (2N−1)π at positions corresponding to the central parts of the second photosensitive cells and the third photosensitive cells, where N is an integer greater than 0.

10. The first nanopost to the fourth nanopost are 10. The image sensor of claim 9, wherein, immediately after passing through the color separation lens array, the light of the second wavelength forms a phase distribution of (2M−1)π at positions corresponding to the central parts of the first photosensitive cells and the fourth photosensitive cells, a phase distribution of 2Mπ at a position corresponding to the central part of the second photosensitive cells, and a phase distribution larger than (2M−2)π and smaller than (2M−1)π at a position corresponding to the central part of the third photosensitive cell, where M is an integer larger than 0.

11. The first nanopost to the fourth nanopost are 11. The image sensor according to claim 10, wherein, immediately after passing through the color separation lens array, the light of the third wavelength forms a phase distribution of (2L-1)π at positions corresponding to the central parts of the first and fourth photosensitive cells, a phase distribution of 2Lπ at a position corresponding to the central part of the third photosensitive cell, and a phase distribution larger than (2L-2)π and smaller than (2L-1)π at a position corresponding to the central part of the second photosensitive cell, where L is an integer larger than 0.

12. the image sensor has a pixel array structure in which a plurality of unit pixels including red pixels, green pixels, and blue pixels are arranged in a Bayer pattern; 12. The image sensor of claim 9, wherein the nanoposts provided in the regions corresponding to green pixels in the first to fourth regions have different distribution patterns along a first direction and a second direction perpendicular to the first direction.

13. 13. The image sensor of claim 12, wherein the nanoposts provided in the regions corresponding to blue and red pixels in the first to fourth regions have a symmetrical distribution pattern along the first direction and the second direction.

14. 13. The image sensor of claim 12, wherein in the first to fourth regions, the nanoposts located at the center of the region corresponding to the green pixel have a larger cross-sectional area than the nanoposts provided in the regions corresponding to the pixels of other colors.

15. 13. The image sensor of claim 12, wherein the nanoposts provided in the first to fourth regions corresponding to green pixels have a cross-sectional area in the center that is larger than that of the nanoposts provided in the periphery.

16. 16. The image sensor according to claim 1, wherein the color separation lens array further includes a plurality of first regions and a plurality of second regions that are arranged to protrude from an edge of the sensor substrate and that do not face any of the photosensitive cells of the sensor substrate in the vertical direction.

17. At least one of the first nanoposts and the second nanoposts includes a lower post and an upper post stacked on the lower post; 17. The image sensor according to claim 1, wherein the lower post and the upper post are stacked so as to be offset from each other.

18. The image sensor of claim 17 , wherein the degree of misalignment between the lower posts and the upper posts increases from the center to the periphery of the image sensor.

19. an imaging unit that focuses light reflected from a subject to form an optical image; and the image sensor according to any one of claims 1 to 18, which converts an optical image formed by the imaging section into an electrical signal.

20. 20. The electronic device of claim 19, wherein the electronic device is a smartphone, a mobile phone, a personal digital assistant (PDA), a laptop, a personal computer (PC), a home appliance, a security camera, a medical camera, an automobile, or an Internet of Things (IoT) device.

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