Image pickup element and image pickup device

Abstract

The imaging element disclosed in the present invention comprises: a pixel array, in which a plurality of pixels including a photoelectric conversion element are arranged in an array on a substrate; a transparent layer formed on the pixel array; and a spectroscopic element array, in which a plurality of spectroscopic elements are arranged in an array at a position corresponding to each of the plurality of spectroscopic elements inside or above the transparent layer. Each of the spectroscopic elements comprises a plurality of fine structures formed of a material having a refractive index higher than that of the transparent layer. The plurality of fine structures have a fine structure pattern. Each of the spectroscopic elements separates incident light into deflected light having different propagation directions according to wavelengths and emits the deflected light.

Description

Technical Field

[0001] The present invention relates to an imaging element and an imaging device including the imaging element. Background Art

[0002] Generally speaking, in order to obtain color information of a photographed object in an imaging element having a photoelectric conversion element such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor, it is necessary to perform color separation of incident light on each pixel including the photoelectric conversion element.

[0003] Figure 1 1 is a cross-sectional view of a general color imaging element. In a conventional color imaging element 100, a photoelectric conversion element 102 is arranged on an electrical wiring 112, and a subtractive color filter 104 made of an organic material or an inorganic material is arranged opposite to each pixel including the photoelectric conversion element 102. A microlens 103 is arranged on the color filter 104. When light is incident from the microlens 103, the color filter 104 is used to transmit only light of a desired wavelength band and absorb or reflect light of an unnecessary wavelength band, thereby obtaining each signal from the three photoelectric conversion elements 102 corresponding to red (R), green (G), and blue (B) for each pixel, thereby generating a color two-dimensional image.

[0004] However, in the general color imaging element 100 as described above, in the case of incident light with RGB in a ratio of 1:1:1, there is a problem that the total amount of light after passing through the color filter 104 is inevitably reduced to about 1 / 3. The remaining light is lost due to absorption or reflection by the color filter 104 and cannot be used to form an image. Therefore, the light utilization efficiency of the incident light is about 30% at most, and the sensitivity of the imaging element is greatly limited. In recent years, the miniaturization of pixels (higher resolution of images) has been promoted, and the amount of light received by one pixel has inevitably decreased, and it is expected to reduce the limitation of the sensitivity of the above-mentioned imaging element.

[0005] As a method for reducing the limitation of the sensitivity of the imaging element, it is proposed to use a spectral element such as a prism or a dichroic mirror that can branch the incident light according to the wavelength band to replace the color filter 104 to form a color imaging element. In principle, such a method can greatly reduce the loss of incident light, and thus can greatly improve the light utilization efficiency compared to the case of using the color filter 104. However, in recent years, the miniaturization of pixels has been advancing, and it is difficult to integrate a spectral element such as a prism or a dichroic mirror on a photoelectric conversion element while maintaining its functions and characteristics.

[0006] Therefore, in recent years, it has been proposed to use a spectroscopic element including a microstructure that is relatively easy to integrate on a photoelectric conversion element to form a color imaging element. In Non-Patent Document 1, it is proposed to use two microstructures that can separate incident light into two wavelength regions to eliminate light loss in color separation in principle, thereby improving light utilization efficiency.

[0007] Figure 2 (a) shows a top view of a color imaging element 200 proposed in Non-Patent Document 1. Figure 2 (b) shows its IIb-IIb cross-sectional view, Figure 2 (c) represents its IIc-IIc cross-sectional view. As shown in the figure, the color imaging element 200 replaces the color filter 104 with a fine beam structure 206-1, 206-2 arranged corresponding to the pixel (photoelectric conversion element 102), and separates the incident light into light that advances in a straight line and light that deflects to the left and right according to the wavelength region. This is because, in and around the fine beam structure, the phase delay effect of the incident light is significantly different in one wavelength region, and is roughly the same in another wavelength region. Therefore, on the two-dimensional pixel array, two fine beam structures 206-1, 206-2 with different structural thicknesses are alternately arranged in each column, so that four photoelectric conversion elements 102 adjacent to each other can receive light with different wavelength components. As a result, by performing signal processing using matrix operations on the photoelectric conversion signals output from each photoelectric conversion element 102, the color information is regenerated and a color image can be generated.

[0008] Furthermore, Non-Patent Document 2 proposes a method of improving light utilization efficiency by arranging a binary microstructure of a fixed thickness on a pixel (photoelectric conversion element 102) that can separate incident light into three wavelength regions.

[0009] Figure 3 (a) shows a top view of a color imaging element 300 having a microscopic spectroscopic element 306 proposed in Non-Patent Document 2. Figure 3 (b) shows its IIIb-IIIb cross-sectional view. By using the color imaging element 300 of non-patent document 2, a color image can be generated by reconstructing the color information using signal processing, as in the case of using the color imaging element 200 of non-patent document 1. Furthermore, the light utilization efficiency of the color imaging element 300 of non-patent document 2 exceeds the light utilization efficiency of the color imaging element 200 of non-patent document 1. In addition, the color imaging element 200 of non-patent document 2 has the following advantages: there is no polarization dependence that is a problem in the color imaging element 200 of non-patent document 1, and it is easy to manufacture because it has a binary structure.

[0010] Prior art literature

[0011] Non-patent literature

[0012] Non-patent document 1: Seiji Nishiwaki, Tatsuya Nakamura, Masao Hiramoto, Toshiya Fujii and Masa-aki Suzuki, "Efficient color splitters for high-pixel-density image sensors," Nature Photonics, Vol. 7, March 2013, pp. 240-246

[0013] Non-Patent Literature 2: Masashi Miyata, Mitsumasa Nakajima, Toshikazu Hashimoto, "High-Sensitivity Color Imaging Using Pixel-Scale Color Splitters Based on Dielectric Metasurfaces," ACS Photonics, March 2019, pp1442-1450

[0014] Non-patent document 3: David Sell, Jianji Yang, Sage Doshay, Jonathan A. Fan, "Periodic Dielectric Metasurfaces with High-Efficiency, Multiwavelength Functionalities," Advanced Optical Materials, Vol. 5, 2017, 1700645 Summary of the invention

[0015] In non-patent document 1 and non-patent document 2, as a method for generating color images, a color reconstruction method using signal processing is proposed. However, there are practical problems in the technology disclosed in non-patent document 1 and non-patent document 2. Regarding these color image generation methods, color errors (noise) caused by the signal processing may occur, and the signal-to-noise ratio (SN ratio) of the image may be deteriorated. Therefore, even if the light utilization efficiency, that is, the amount of light received in the sensor is increased by the spectroscopic element, the SN ratio of the camera image may not be improved due to the addition of new noise caused by signal processing, and the actual sensitivity may not be improved. Furthermore, since the signal processing time is required again, the temporal resolution of the camera may be reduced. It should be noted that, as disclosed in non-patent document 2, it is possible to consider setting the shape of the microlens, which is usually a perfect circle, to an ellipse or the shape of the pixel, which is usually a square, to a rectangle, etc., and directly obtain color information based on the signal intensity without using signal processing, but in addition to the fact that the change in the shape of the lens or pixel may not conform to the existing manufacturing process or post-processing, pixel configuration, etc., there is also the problem of disrupting the uniformity of the spatial resolution of the image, so it lacks feasibility.

[0016] The present disclosure has been made in view of the above-mentioned problems, and an object of the present disclosure is to provide an imaging element and an imaging device that can generate an image with high sensitivity without using color reconstruction by signal processing.

[0017] In order to solve the above-mentioned problems, an imaging element of one embodiment of the present invention comprises: a pixel array, in which a plurality of pixels including a photoelectric conversion element are arranged in an array on a substrate; a transparent layer formed on the pixel array; and a spectroscopic element array, in which a plurality of spectroscopic elements are arranged in an array at a position inside or above the transparent layer corresponding to each of the plurality of pixels, each of the spectroscopic elements comprises a plurality of fine structures formed of a material having a refractive index higher than that of the transparent layer, the plurality of fine structures having a fine structure pattern, and each of the spectroscopic elements separates incident light into deflected light having different propagation directions according to wavelengths and emits the deflected light.

[0018] According to one embodiment of the present invention, an imaging element that can reduce the burden of signal processing for color reconstruction and generate images with high sensitivity and an imaging device having the imaging element can be realized. The generated image can be set as a color image based on a photoelectric conversion signal in which visible light incident on the imaging element is converted into an electrical signal. Alternatively, the generated image can be set as an image based on a photoelectric conversion signal in which infrared light or ultraviolet light incident on the imaging element is converted into an electrical signal. Therefore, the concern about image degradation due to signal processing can be reduced, and the benefit of the improved light utilization efficiency achieved by the micro-spectrometric element can be directly reflected in the improved imaging sensitivity. In addition, the imaging element of one embodiment of the present invention has the following advantages, namely: the imaging element can be constructed using a widely used perfect circular microlens or a square pixel shape. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a cross-sectional view of a general color imaging element.

[0020] Figure 2 (a) is a top view of the color imaging element proposed in Non-Patent Document 1; Figure 2 (b) is Figure 2 IIb-IIb cross-sectional view of (a); Figure 2 (c) is Figure 2 (a) IIc-IIc cross-sectional view.

[0021] Figure 3 (a) is a top view of a color imaging element proposed in Non-Patent Document 2. Figure 3 (b) is Figure 3 (a) IIIa-IIIb cross-sectional view.

[0022] Figure 4 It is a side view showing a schematic configuration of an imaging device 10 according to an embodiment of the present invention.

[0023] Figure 5 (a) is a diagram schematically showing a part of the structure of an imaging element 500 including a pixel array and a spectroscopic element array when viewed from the top surface; Figure 5 (b) is a schematic representation of Figure 5 (a) Vb-Vb cross-section diagram.

[0024] Figure 6 (a) is a diagram schematically showing a part of the structure of the imaging element 600 including a pixel array and a spectroscopic element array when viewed from the top surface, Figure 6 (b) is a schematic representation of Figure 6 (a) is a diagram of the VIb-VIb section.

[0025] Figure 7 (a) to (c) are diagrams showing examples of phase delay distributions that realize spectral characteristics for spatially separating incident light in three directions for each of three wavelength regions (R, G, and B).

[0026] Figure 8 (a) is a top view of an example of a microstructure constituting the micro spectroscopic element 101 of this embodiment. Figure 8 (b) is a side view of an example of a microstructure.

[0027] Fig. 9 (a), (d) and (g) are top views of an example of the microscopic spectroscopic element 101 of this embodiment; Fig. 9 (b), (e) and (h) are related to Fig. 9 (a), (d) and (g) are side views of the microscopic spectroscopic element 101; Fig. 9 (c), (f) and (i) are Fig. 9 Graphs showing the phase delay distribution (line) of the microscopic spectroscopic element 101 corresponding to (a), (d) and (g) and the ideal phase delay distribution (line).

[0028] Fig.10 (a), (c), and (e) represent Fig. 9 (b), (e), and (h) are diagrams respectively corresponding to the propagation of light of the microscopic spectroscopic element 101. Fig.10 (b), (d), and (f) represent Fig.10 (a), (c), and (e) are graphs showing the wavelength dependence of the efficiency of the spectroscopic function of a micro-spectral element.

[0029] Fig.11 (a) to (c) are diagrams schematically showing examples of the arrangement of pixels including the photoelectric conversion element 102 .

[0030] Fig.12 (a) to (c) are diagrams schematically showing still another example of the arrangement of pixels including the photoelectric conversion element 102 .

[0031] Fig.13 This is a diagram schematically showing a part of the cross-sectional structure of the imaging element 700 including a pixel array and a spectroscopic element array. DETAILED DESCRIPTION

[0032] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the following embodiments are merely examples, and the present invention is not limited to these embodiments.

[0033] Figure 41 is a side view showing a schematic configuration of an imaging device 10 according to an embodiment of the present invention. The imaging device 10 includes a lens optical system 11, an imaging element 12, and a signal processing unit 13 that processes a photoelectric conversion signal output from the imaging element 12 to generate an image signal.

[0034] Light such as natural light or illumination light is irradiated onto the object 1, and light transmitted / reflected / scattered by the object 1, or light emitted from the object 1, forms an optical image on an imaging element 12 including a photoelectric conversion element such as a CCD or CMOS through a lens optical system 11. Generally speaking, a lens optical system is composed of a lens group including a plurality of lenses arranged along an optical axis in order to correct various optical aberrations. Figure 4 The accompanying drawings are simplified and represented as a single lens. The signal processing unit 13 has an image signal output, which processes the photoelectric conversion signal output from the imaging element 12 and generates an image signal, and sends the generated image signal to the outside. It should be noted that the imaging device 10 of the present invention may have well-known components such as an optical filter that cuts off infrared light, an electronic shutter, a viewfinder, a power supply (battery), a flash, etc., because their description is not particularly necessary for understanding the embodiments of the present invention, it is omitted. In addition, the above structure is only an example. In one embodiment of the present invention, for components other than the lens optical system 11, the imaging element 12, and the signal processing unit 13, well-known components can be appropriately combined and used.

[0035] Before describing the details of the embodiment of the present invention, an overview of the imaging element 12 of the embodiment of the present invention will be described first. The imaging element 12 of the embodiment of the present invention includes a micro spectroscopic element 101 and pixels including a photoelectric conversion element 102. A plurality of pixels including the photoelectric conversion element 102 are arranged two-dimensionally to form a pixel array. In addition, a plurality of micro spectroscopic elements 101 are arranged two-dimensionally in a manner opposite to the pixels including the photoelectric conversion element 102 to form a spectroscopic element array. Each of the plurality of pixels is arranged at a position corresponding to each of the plurality of spectroscopic elements. The position corresponding to each of the spectroscopic elements refers to, for example, a state in which each pixel of the pixel array overlaps in a projection plane descending toward the pixel array in a direction perpendicular to the element surface from an area occupied by each spectroscopic element.

[0036] exist Figure 5 (a) schematically shows a part of the structure of an imaging element 500 including a pixel array and a spectroscopic element array when viewed from the top surface as an example of the imaging element 12; Figure 5(b) schematically shows a part of the structure of the imaging element 500 at the Vb-Vb section. The spectroscopic element array is opposite to the pixel array. The spectroscopic element array is arranged on the side where light from the lens optical system 11 is incident. A transparent layer 111 is provided between the spectroscopic element array and the pixel array, and on the lens optical system 11 side of the spectroscopic element array. An electrical wiring 112 (not shown) is provided on the side of the pixel array opposite to the spectroscopic element array.

[0037] Each micro spectroscopic element 101 constituting the spectroscopic element array has a fine structure pattern with a fixed thickness (length in the y-axis direction). More specifically, each micro spectroscopic element 101 has a fine structure pattern with a fixed thickness, but the shapes of the upper and lower surfaces are different depending on the position of the arrangement. The details of the fine structure pattern will be described later. It should be noted that the micro spectroscopic element 101 may also be a fine structure body with a thickness that varies depending on the position. In addition, there is no limitation on the fine structure pattern, and various arrangements may be adopted. It should be noted that the imaging element 12 of the embodiment of the present invention may have well-known constituent elements such as microlenses or light-shielding walls, but their description is not particularly necessary for a general understanding of the present invention, so they are not described in detail. Figure 5 It is omitted in.

[0038] The description of this embodiment classifies the light incident on the imaging element 12 into a first wavelength region, a second wavelength region, and a third wavelength region according to each wavelength region, but is not limited to this. It should be noted that the combination of the first to third wavelength regions is generally the three primary colors of red (R), green (G), and blue (B), but is not limited to this. For example, the combination of wavelength regions may be a combination of multiple different wavelength regions in the wavelength region of infrared light, or a combination of multiple different wavelength regions in the wavelength region of ultraviolet light. Each of the microscopic spectroscopic element arrays constituting the embodiment of the present invention has the following function, namely: utilizing the phase delay effect caused by the fine structure described later, its structural size dependence and wavelength dependence, to change the propagation direction of the light incident on the imaging element 12 according to the above-mentioned first to third wavelength regions, and spatially separate the light on the pixel array. That is, in the embodiment of the present invention, the light incident on the imaging element 12 is separated into three directions of the first direction (left), the second direction (straight ahead), and the third direction (right) according to the wavelength region by each micro-spectrometric element 101, and is incident on a plurality of pixels. As a more detailed example, the case where the micro-spectrometric element 101 separates blue (B) into the first direction (left), green (G) into the second direction (straight ahead), and red (R) into the third direction (right) is described. The light in the blue (B) wavelength region is incident on the pixel corresponding to blue (adjacent to the left side of the pixel corresponding to green) as light with a wide extension width in the x-axis direction (light with a uniform wavelength component) (the incident angle of the short-wavelength light is different from the incident angle of the long-wavelength light). The light in the red (R) wavelength region is incident on the pixel corresponding to red (adjacent to the right side of the pixel corresponding to green) as light with a wide extension width in the x-axis direction (light with a uniform wavelength component) (the incident angle of the short-wavelength light is different from the incident angle of the long-wavelength light). Light in the green (G) wavelength region is incident on a pixel corresponding to green disposed at a position corresponding to the microscopic spectroscopic element as light with a narrow width that does not expand in the x-axis direction (the incident angle of short-wavelength light is approximately equal to the incident angle of long-wavelength light).

[0039] In addition, when three adjacent micro-spectrometers 101 along a plane uniaxial direction (the x-axis direction of the xy plane) are set as a spectrometer unit, the spectrometer functions of the three micro-spectrometers 101 constituting a spectrometer unit are different. Specifically, a spectrometer unit includes three types of micro-spectrometers. For example, the first type of micro-spectrometer has a spectrometer function that separates the light in the first wavelength region, the second wavelength region, and the third wavelength region into a first direction (left), a second direction (straight forward), and a third direction (right), respectively. The second type of micro-spectrometer has a spectrometer function that separates the light in the first wavelength region, the second wavelength region, and the third wavelength region into a third direction (right), a first direction (left), and a second direction (straight forward), respectively. The third type of micro-spectrometer has a spectrometer function that separates the light in the first wavelength region, the second wavelength region, and the third wavelength region into a second direction (straight forward), a third direction (right), and a first direction (left), respectively.

[0040] Therefore, the distance between the micro-spectrometer 101 and the pixel including the photoelectric conversion element 102 is set to the distance at which the light separated into the second direction (straight forward) by the micro-spectrometer 101, the light separated into the first direction (left) by the micro-spectrometer adjacent to the right side of the micro-spectrometer 101, and the light separated into the third direction (right) by the micro-spectrometer adjacent to the left side of the micro-spectrometer 101 enters the photoelectric conversion element 102, thereby, the three pixels (photoelectric conversion elements 102) located directly below each spectroscopic unit only receive light in any one of the first, second, and third wavelength regions. When light enters the pixel, the photoelectric conversion element 102 outputs an electrical signal (photoelectric conversion signal) corresponding to the intensity of the incident light, so that the signal corresponding to the wavelength region (color information if it is the three primary colors) can be directly obtained. Since the micro spectroscopic element 101 and the plurality of pixels (photoelectric conversion elements 102) corresponding to the micro spectroscopic element 101 are arranged two-dimensionally, information of each wavelength region of the optical image of the object formed by the lens optical system can be simultaneously acquired without using special signal processing.

[0041] In the first embodiment described later, the first to third wavelength regions are set as the three primary colors of R, G, and B, and the incident light is spatially separated into three directions by the micro-spectrometric element 101 according to each wavelength region of R, G, and B. That is, substantially all of the incident light is incident on the three pixels (photoelectric conversion elements 102) located directly below the spectroscopic unit in a state of being separated into wavelength regions of R, G, and B. Therefore, color information can be directly obtained from the photoelectric conversion signal obtained from the pixel (photoelectric conversion element 102) without a large light loss.

[0042] In addition, regarding the second embodiment described later, the first to third wavelength regions are set as the three primary colors of R, G, and B, and the micro-spectrometric element 101 spatially separates the incident light into three directions according to each wavelength region of R, G, and B. Furthermore, the light-reducing bandpass filter (color filter 104) corresponding to each wavelength region of the separated light filters the light separated into three directions. That is, substantially all of the incident light is separated into wavelength regions of R, G, and B, and is incident on the three pixels (photoelectric conversion element 102) located directly below the spectroscopic unit in a state of being filtered by the bandpass filters corresponding to the wavelength regions. Therefore, in the second embodiment, as in the first embodiment, color information can be directly obtained from the photoelectric conversion signal obtained from the self-pixel (photoelectric conversion element 102) without a large light loss, and the color reproducibility is improved by the filtering effect.

[0043] According to the imaging element of the embodiment of the present invention, by using the light separation of each wavelength region of the micro-spectrometric element, it is possible to obtain information of each wavelength region of the optical image of the object without a large light loss. That is, if the first to third wavelength regions are set as the three primary colors of R, G, and B, a color image can be obtained. In addition, since the information of each wavelength region can be directly obtained and there is no need to use color reconstruction based on signal processing, there is no concern about image degradation caused by color reconstruction, which is a problem in the technology disclosed in non-patent documents 1 and 2. Therefore, the benefit of the improved light utilization efficiency achieved by the micro-spectrometric element can be directly reflected in the improved imaging sensitivity, and the sensitivity of color imaging can be improved compared to the previous imaging element using only color filters. In addition, by using a micro-spectrometric element and a color filter in combination, a higher light utilization efficiency can be maintained and color reproducibility can be improved compared to the previous imaging element using only color filters. Furthermore, the imaging element of the present invention does not require changes to the commonly used microlens shape or pixel shape, and therefore has the following advantages: it is highly compatible with existing manufacturing processes or imaging systems, and the effect can be achieved by simply replacing the color filter that constitutes the previous imaging element with a micro-spectrometric element.

[0044] Below, while referring to the attached Figure 1 Embodiments of the present invention will be described in more detail.

[0045] (First Embodiment)

[0046] The following is a brief description of the configuration of the imaging element of the present embodiment. In the present embodiment, a form in which the incident light is split into each of three wavelength regions (R, G, B) is shown, but the number of wavelength regions to be split or the wavelength of each wavelength region is not limited thereto. For example, at least one of the three wavelength regions may be light of a wavelength other than the three primary colors (e.g., infrared light or ultraviolet light). In addition, in the present embodiment, the spectroscopic elements and pixels of the spectroscopic element array and the pixel array are shown to be arranged in two dimensions, respectively, but the spectroscopic elements and pixels may also be arranged in one dimension, respectively.

[0047] exist Figure 6 In (a), as an example of the imaging element 12, a part of the structure of the imaging element 600 including the pixel array and the spectroscopic element array when viewed from the top surface is schematically shown. Figure 6 (b) shows a part of the structure of the imaging element 600 at the VIb-VIb cross section. The imaging element 600 has a two-dimensional pixel array in which pixels including the photoelectric conversion element 102 are arranged in an array, and a transparent layer 111 with a low refractive index including SiO2 or the like and a plurality of micro lenses 103 are stacked. A microscopic spectroscopic element 101 is embedded in the transparent layer 111 with a low refractive index.

[0048] The micro-spectrometric element 101 includes a plurality of fine structures, which are formed of a material such as SiN or TiO2 having a refractive index higher than that of the transparent layer 111. The plurality of fine structures are formed to have a fine structure pattern. For ease of explanation, in the following description, an xyz orthogonal coordinate system is set with the normal direction of the two-dimensional pixel array (array of the photoelectric conversion element 102) as the z-axis, the horizontal direction parallel to the two-dimensional pixel array as the x-axis, and the direction perpendicular to the x-axis parallel to the two-dimensional pixel array as the y-axis.

[0049] like Figure 6 As shown in (a) and (b), the microlenses 103, micro spectroscopic elements 101 and pixels (photoelectric conversion elements 102) are arranged in a grid shape with the same period on the xy plane to form arrays. A micro spectroscopic element 101 and a pixel (photoelectric conversion element 102) are arranged directly below each microlens 103. The micro spectroscopic element array includes a micro spectroscopic element 101, which spatially separates the incident light into three directions (left, straight ahead, and right) along a direction parallel to the x-axis on a plane according to each of the three wavelength regions (R, G, and B). In addition, if three micro spectroscopic elements 101 adjacent to each other along the x-axis are set as a spectroscopic unit ( Figure 6(represented by a dotted rectangle in (a)), the array of micro-spectrometric elements can be regarded as an array of spectrometric units in a grid shape. The three micro-spectrometric elements 101 constituting the spectrometric unit have different combinations of three directions assigned to each of the three wavelength regions. Specifically, the spectrometric unit has three types of micro-spectrometric elements, and the three types of micro-spectrometric elements include: an element having a spectrometric function that separates the light of R (represented by a solid line), the light of G (represented by a dotted line), and the light of B (represented by a single dotted line) into left, straight, and right, respectively; an element having a spectrometric function that separates the light of R, the light of G, and the light of B into right, left, and straight, respectively; and an element having a spectrometric function that separates the light of R, the light of G, and the light of B into straight, right, and left, respectively.

[0050] It should be noted that, in the above description, as an example, a case where square pixels (photoelectric conversion elements 102) are arranged in a two-dimensional pixel array in an orthogonal grid shape is described, but the arrangement, shape, size, etc. of the pixels are not limited to the example in the figure. Figure 6 Although omitted in (b), a structure may be provided between the two-dimensional pixel array and the micro-spectrographic element array, the structure having a light-gathering function realized by a concave-convex structure including SiN or TiO2 having a higher refractive index than the transparent layer, which acts as an internal microlens to guide the light from the micro-spectrographic element 101 toward the photoelectric conversion element 102 in the pixel. The structure may also be a plate having a higher refractive index than the transparent layer. Figure 6 The structures shown in (a) and (b) can be manufactured using semiconductor manufacturing technology.

[0051] It should be noted that Figure 6 The imaging element 600 shown in (a) and (b) has a back-illuminated structure in which light is incident from the opposite side of the wiring layer on which the electrical wiring 112 is formed, but in the present embodiment, it is not limited to such a structure, for example, it may also have a front-illuminated structure in which light is received from the side of the wiring layer.

[0052] Hereinafter, the function of each component of the image sensor 600 according to the present embodiment will be described.

[0053] The white light incident on the imaging element 600 is first focused by the microlens array, and almost all of the light passes through the microscopic spectroscopic elements 101 corresponding to each microlens 103. Each microscopic spectroscopic element 101 spatially separates the light into three directions according to each of the three wavelength regions, and receives the light respectively by three pixels (photoelectric conversion elements 102) located directly below each microscopic spectroscopic element 101. Since each pixel of the pixel array located directly below the microscopic spectroscopic element array is incident with light of any wavelength range of R, G, and B according to the configuration of the spectroscopic unit, each pixel corresponds to the detection of color information of any one of R, G, and B. Finally, the photoelectric conversion is performed by the photoelectric conversion element 102 in each pixel, and is output as an image signal including color information.

[0054] It should be noted that between the pixel array and the micro-spectrometric element, there may be a structure having a focusing function achieved by a concave-convex structure including SiN or TiO2, etc., which acts as an internal microlens and has a higher refractive index than the transparent layer, or a structure having a focusing function achieved by a plate including SiN or TiO2, etc., which has a higher refractive index than the transparent layer. However, since the micro-spectrometric element 101 described later can have a lens function through the phase delay distribution formed, the internal microlens can also be omitted.

[0055] The following is an explanation of the micro-spectrometer element 101 of the present embodiment. As described above, the micro-spectrometer element 101 spatially separates the incident light in three directions according to each of the three wavelength regions (R, G, B). To this end, it is necessary to give a different phase delay distribution for each wavelength region to the light passing through one micro-spectrometer element 101, thereby changing the light wavefront.

[0056] Figure 7 (a) shows an example of a phase delay distribution of a spectral characteristic that spatially separates incident light into three wavelength regions (R, G, B) in three directions. Figure 7 In the phase delay distribution shown in (a), the phase delay distribution of the wavelength corresponding to the first wavelength region (R) is on a straight line where the phase amount in the x-axis direction decreases linearly from 0 to -2π at a distance of one micro-spectrometer, the phase delay distribution of the wavelength corresponding to the second wavelength region (G) has no spatial change, and the phase delay distribution of the wavelength corresponding to the third wavelength region (B) is on a straight line where the phase amount in the x-axis direction increases linearly from 0 to +2π at a distance of one micro-spectrometer. In this case, in the light passing through the micro-spectrometer 101, R can be efficiently propagated in the first direction (left), G in the second direction (straight forward), and B in the third direction (right). It should be noted that the above description is an example, and the combination of wavelength regions and propagation directions can also be freely changed according to the phase delay distribution.

[0057] Therefore, here, if we assign Figure 7 The phase distribution shown in (b) is the following phase delay distribution: the phase delay distribution of the wavelength corresponding to the second wavelength region (G) is on a straight line where the phase amount in the x-axis direction decreases linearly from 0 to -2π at a distance of the amount of a tiny spectrometer, the phase delay distribution of the wavelength corresponding to the third wavelength region (B) has no spatial change, and the phase delay distribution of the wavelength corresponding to the first wavelength region (R) is on a straight line where the phase amount in the x-axis direction increases linearly from 0 to +2π at a distance of the amount of a tiny spectrometer. R can be efficiently propagated to the right, G to the left, and B to the straight-line forward direction, respectively.

[0058] In addition, here, if given Figure 7 The phase delay distribution shown in (c) is the following phase distribution: the phase delay distribution of the wavelength corresponding to the third wavelength region (B) is on a straight line where the phase amount in the x-axis direction decreases linearly from 0 to -2π at a distance of the amount of a tiny spectrometer, the phase delay distribution of the wavelength corresponding to the first wavelength region (R) has no spatial change, and the phase delay distribution of the wavelength corresponding to the second wavelength region (G) is on a straight line where the phase amount in the x-axis direction increases linearly from 0 to +2π at a distance of the amount of a tiny spectrometer. R can be efficiently propagated in the straight-line forward direction, G can be propagated to the right, and B can be propagated to the left, respectively.

[0059] The above phase delay distribution can be realized by appropriately designing the material, number, shape, size, pattern, etc. of the fine structure as described later. That is, the micro spectroscopic element 101 of this embodiment arranges the fine structure on a two-dimensional plane, and gives different light wavefronts according to the wavelength region to the incident light, thereby spatially separating the color components.

[0060] Figure 8 (a) shows the top surface of an example of a microstructure constituting the micro spectroscopic element 101 of this embodiment. Figure 8 (b) shows a side view of the microstructure. The columnar structure 121, which is an example of a microstructure, includes a material such as SiN or TiO2 having a refractive index n1 higher than the refractive index n0 of the transparent layer 111, and the thickness h of the structure is set to be fixed. In addition, the bottom and top surfaces of the columnar structure 121 are square. The columnar structure 121 can be considered as an optical waveguide that confines light within the structure and propagates it based on the refractive index difference between the transparent layer 111 and the columnar structure 121. Therefore, light incident from the top surface is strongly confined in the columnar structure 121 and propagates, receiving the refractive index n1 of the effective optical waveguide. effSpecifically, when the phase of light having a length equal to the thickness of the propagation structure in the transparent layer 111 is used as a reference, the phase delay φ of the columnar structure 121 is expressed by equation (1) when the wavelength of light in vacuum is λ.

[0061] φ=(n eff -n0)×2πh / λ···(1)

[0062] Since the phase delay φ varies depending on the wavelength λ of the light, the same columnar structure 121 can provide different phase delays to the light depending on the wavelength region (color component). eff is a function of the width w of the columnar structure 121, and n0<n eff <n1 value. Therefore, Figure 8 In the examples shown in (a) and (b), various combinations of phase delay amounts corresponding to the wavelength λ of light can be set by changing the width w of the columnar structure 121. In addition, since the bottom and top surfaces of the columnar structure 121 are square, even when the polarization direction of the incident light is changed, the optical characteristics including the phase delay effect do not change.

[0063] Suitable for reference Figure 7 (a) to (c) and the above-mentioned phase delay distribution method, the columnar structure 121 as above is set according to the position of the width w of the columnar structure, and multiple columns are arranged on a two-dimensional plane, thereby realizing the micro-spectrometric element 101 of this embodiment. In addition, in the configuration of each columnar structure 121 mentioned above, in order to prevent the generation of unnecessary diffraction light caused by the periodic structure, it is ideal to arrange multiple columnar structures 121 at intervals p less than the wavelength of the light. It should be noted that in order to effectively deflect the light, the phase delay distribution is suitable for a distribution ranging from 0 to ±2π, so in each wavelength range, the variable range of the phase delay amount of the columnar structure 121 is preferably greater than 2π. Therefore, according to formula (1), if the desired central wavelength of the wavelength range on the longest wavelength side of the separated wavelength range is set to λr, the thickness h of the structure is ideally set to h=λr / (n1-n0) or more. In the above example, the bottom and top surfaces of the columnar structure 121 are square, but the shape is not limited to this. That is, if the shape surface is four-fold rotationally symmetrical with the center of the surface as the symmetry axis, the dependence of the light splitting function on polarization will not occur, and the action as an optical waveguide that brings about the phase delay effect will not be lost. Therefore, it is ideal to use a columnar structure having a surface that is four-fold rotationally symmetrical, such as a square, a hollow square, a circle, a hollow circle, or a cross.

[0064] A more detailed example of the micro-spectral element 101 according to the present embodiment will be described.

[0065] Fig. 9 (a), (d) and (g) are top views of an example of the microscopic spectroscopic element 101 of this embodiment. Fig. 9 (b), (e) and (h) represent Fig. 9 (a), (d) and (g) are side views of an example of a microscopic spectroscopic element 101, Fig. 9 (c), (f) and (i) represent Fig. 9 Phase delay distribution (line) and ideal phase delay distribution (line) of each micro-spectrometer 101 corresponding to (a), (d) and (g) for three wavelengths (λ1=430nm, λ2=520nm, λ3=635nm). As shown in the figure, three columnar structures with different widths and fixed thicknesses are arranged in the x-axis direction (columnar structures with fine structural patterns with different widths of the top and bottom surfaces depending on the configuration position), and three columnar structures with the same width and fixed thickness are arranged in the y-axis direction, which constitute a micro-spectrometer 101. It should be noted that the material constituting the columnar structure 121 is SiN (n1=2.03). In addition, the material constituting the transparent layer 111 above the columnar structure 121 is SiO2 (n0 = 1.45), and the material constituting the transparent layer between the columnar structures 121 and the transparent layer below the columnar structure 121 (on the opposite side of the transparent layer 111) is air (n0 = 1.0). It is also possible to bury the columnar structure 121 in a single transparent layer instead of two transparent layers with different refractive indices. In addition, here, an example of arranging three columnar structures is described, but as long as a plurality of columnar structures are arranged, it is not necessary to arrange three.

[0066] Fig. 9 The columnar structures 121 of (a), (d), and (g) represent examples in which the bottom and top surfaces are square. The thickness h of all the columnar structures 121 is 1250 nm, and the interval p between the structures in the x-axis and y-axis directions is 400 nm. Therefore, the area of ​​one element is 1.2 μm×1.2 μm. Based on the above conditions, by setting the widths w1, w2, and w3 of the three columnar structures 121-1, 121-2, and 121-3 according to the positions in a manner suitable for an ideal phase delay distribution, an element ("RGB" ( Fig. 9 (a)))) and a light-splitting element ("GBR" ( Fig. 9(d))) and an element ("BRG" ( Fig. 9 (g))) and other three kinds of microscopic light-splitting elements. In this way, even if Figure 7 Although the value of the position x of the phase delay distribution as shown in (a), (b), and (c) is not 0, it is sufficient to design the widths w1, w2, w3, etc. in such a way that the positional relationship between the fine structures and the phase delay amount of each wavelength are arranged linearly.

[0067] Fig.10 (a), (c), and (e) represent the Fig. 9 (b), (e), and (h) correspond to the three situations in which the parallel light incident on the top surface of the micro-spectrometric element 101 is separated into right (+1st), left (-1st), and straight forward (0th) and propagates. Fig.10 (b), (d), and (f) indicate Fig.10 The wavelength dependence of the efficiency of the spectroscopic function of the micro-spectroscopy elements (the efficiency of separation into three directions (-1st, 0th, +1st) and propagation (the ratio of the light intensity in each propagation direction to the light intensity of the incident light)) of (a), (c), and (e) (calculation results based on strict coupled wave theory). It should be noted that in the calculation, it is assumed that the above-mentioned micro-spectroscopy elements 101 are arranged at intervals of P (P = 3p) in the x-axis and y-axis directions, but it has been confirmed that there is almost no difference in the optical function of the micro-spectroscopy element 101 as a single unit. In addition, the deflection angle θ in each of the three directions －1st ,θ 0th ,θ +1st It is based on the diffraction of light. When the wavelength of light is λ, the left (-1st) is sinθ －1st =λ / P, with respect to the straight line (0th) as θ 0th = 0, and sinθ is set on the right (+1st) +1st =λ / P.

[0068] Fig.10 The characteristics shown in (b), (d), and (f) are equivalent to the spectral characteristics of the color filter of the conventional imaging element. Fig.10 From (b), we can see that Fig.10 The efficiency of the micro-spectrometric element ("RGB" element) shown in (a) forms a peak in the left (-1st) direction in the red wavelength range above 600nm, the efficiency in the straight forward (0th) direction forms a peak in the green wavelength range of 500nm to 600nm, and the efficiency in the right (+1st) direction forms a peak in the blue wavelength range below 500nm. Similarly, Fig.10 From (d), we can see that Fig.10The efficiency of the micro-spectrometric element ("GBR" element) shown in (c) forms a peak in the green wavelength range of 500nm to 600nm in the left (-1st) direction, forms a peak in the blue wavelength range below 500nm in the straight forward (0th) direction, and forms a peak in the red wavelength range above 600nm in the right (+1st) direction. In addition, as Fig.10 From (f), we can see that Fig.10 The efficiency of the micro-spectrometric element ("BRG" element) shown in (e) forms a peak in the blue wavelength range below 500nm in the left (-1st) direction, forms a peak in the red wavelength range above 600nm in the straight forward (0th) direction, and forms a peak in the green wavelength range from 500nm to 600nm in the right (+1st) direction. In addition, a good spectroscopic performance with an efficiency of 40% to 80% is shown, and it is confirmed that there is no large polarization dependence in the characteristics. It should be noted that the total transmittance of light is more than 80%, and there is almost no light loss due to scattering or reflection. Based on the above, it can be seen that by using the micro-spectrometric element of this embodiment, the color components can be spatially separated with high efficiency. Furthermore, in the above example, the size of the single micro-spectrometric element is 1.2μm×1.2μm, which is the same as the minimum pixel size of an ordinary CMOS sensor. Therefore, a micro-spectrometric element corresponding to a pixel array with the current minimum pixel size can be formed. It should be noted that the microscopic spectroscopic elements 101 of different sizes may be formed according to the size, number, or arrangement pattern of the columnar structures 121 .

[0069] In addition, the micro-spectrometric element 101 of the present embodiment is not limited to the above-mentioned columnar structure 121, and various forms of micro-structures can be used. For example, as disclosed in non-patent document 3, a micro-structure having a structure pattern optimized by a computer and a fixed thickness can form a phase delay distribution for each wavelength region based on the same principle as the above-mentioned principle, and can spatially separate the color components. Furthermore, according to formula (1), in addition to changing the structure width w, the thickness h of the structure is also changed, thereby setting more diverse combinations of phase delay amounts corresponding to the wavelength λ of light. Therefore, the width w and thickness h of the micro-structure are set separately according to the position where the micro-structure is configured in a manner suitable for the above-mentioned phase delay distribution, and the micro-spectrometric element of the present embodiment can be realized even if multiple micro-structures are configured on a two-dimensional plane.

[0070] The micro spectroscopic element 101 having the above-mentioned spectroscopic function can be manufactured by performing thin film deposition and patterning using a well-known semiconductor manufacturing technology.

[0071] As described above, the desired spectral characteristics can be imparted by appropriately designing the material, number, shape, size, pattern, etc. of the structure constituting the micro-spectrometric element. As a result, as described above, the light of the desired wavelength region can be separated and incident on each pixel, so that the signal corresponding to the wavelength region can be directly obtained from the photoelectric conversion signal output from the photoelectric conversion element in each pixel. In addition, if the material constituting the micro-spectrometric element is low-loss, almost no light loss occurs, so compared with the imaging element using the filter of the prior art, the total amount of light reaching the pixel array can be dramatically increased, and the sensitivity of color imaging can be improved. It should be noted that even if the spectral performance of each micro-spectrometric element is slightly different from the ideal performance described above, the acquired signal can be corrected / calculated according to the degree of performance difference to obtain good color information.

[0072] It should be noted that after the color components are separated by the micro-spectrometer, in order to minimize the optical crosstalk between pixels on the pixel array, it is ideal that the separated light is incident near the center of each pixel. Therefore, when the angle between the propagation direction of the light deflected by the micro-spectrometer and the normal direction of the pixel array is set to θ, and the period of the pixel array is set to P, the interval between the output end of the micro-spectrometer and the photoelectric conversion element is preferably near P / tanθ.

[0073] Hereinafter, the arrangement of micro-optical elements and pixels of the image sensor according to the present embodiment will be described.

[0074] exist Figure 6 In the example shown in (a) and (b), the rows of microscopic spectroscopic elements 101 arranged along the x-axis direction are repeatedly arranged along the y-axis direction without shifting in the x-axis direction, resulting in a pattern of microscopic spectroscopic elements being arranged continuously along the y-axis direction. In this case, in the x-axis direction, three pixels (photoelectric conversion elements 102) corresponding to the color component that goes straight ahead (0th) directly below each microscopic spectroscopic element are arranged in the order of R, G, and B from the left, and the arrangement is repeated.

[0075] Fig.11 (a) to (c) of FIG. 1 are diagrams schematically showing the arrangement of pixels (photoelectric conversion elements 102) corresponding to the above-mentioned color components. R represents the pixel corresponding to R, D G represents the pixel corresponding to G, D B In this case, when three pixels adjacent to each other in the x-axis direction are set as one color pixel unit, Fig.11Each of the color pixel unit u1 shown in (a) and the color pixel unit u2 offset by a single pixel in the x-axis direction relative to the color pixel unit u1 must include a pixel corresponding to R, G, and B. That is, if the color pixel units are offset by a single pixel in the xy plane while acquiring color information, the information of the three colors of R, G, and B can be obtained roughly in the amount of the number of pixels. This means that the resolution of the imaging element can be increased to the degree of the number of pixels. Therefore, in addition to being highly sensitive, the imaging element 12 of this embodiment can also generate color information with a high resolution of a single pixel.

[0076] The configuration of the micro-optical elements and pixels to achieve the above-mentioned single pixel resolution is not limited to Fig.11 (a) and various changes can be made. Fig.11 (b) and Fig.11 (c) shows another example, where the microscopic spectroscopic element 101 and the color pixel unit are arranged along the x-axis direction. Fig.11 In (b), the amount of 1 pixel is Fig.11 In (c), the pixels are offset in the x-axis direction by 2 pixels and arranged in sequence in the y-axis direction. This arrangement can also be combined with Fig.11 (a) also generates color information at a resolution of a single pixel.

[0077] Fig.12 (a) to (c) indicate that they are different from Fig.11 In another example of the arrangement of (a) to (c), pixels D corresponding to R are arranged in each column. R , pixel D corresponding to G G , pixel D corresponding to B B The order of left and right is reversed, and the offset in the x-axis direction is respectively the same as the above Fig.11 In this case, it is also possible to Fig.11 (a) also generates color information at a resolution of a single pixel. R , pixel D G , pixel D B The order of the pixel units is reversed by using a pattern obtained by reversing the pattern of the columnar structure 121 of the microscopic spectroscopic element 101. Fig.12 Similarly, in (a) to (c), three pixels D are arranged in each column. B , D R , D G The same color information can be generated by reversing the order of left and right and shifting in the x-axis direction. Fig.12 Similarly, in (a) to (c), the order of three pixels is reversed left-right and right-left for each column and shifted in the x-axis direction, and the same color information can be generated.

[0078] (Second Embodiment)

[0079] Next, the outline of the configuration of an image pickup device according to a second embodiment of the present invention will be described.

[0080] exist Fig.13 , a schematic part of a cross section of an imaging element 700 according to the present embodiment of the present invention is shown as an example of the imaging element 12. Fig.13 It is clear that the imaging element 700 of this embodiment is different from the imaging element 600 ( Figure 6 Compared with (b) of the first embodiment, the color filter 104 corresponding to each color component is arranged above the pixel (photoelectric conversion element 102) corresponding to the color component. It should be noted that the other components are the same. The following description focuses on the differences from the imaging element 600 of the first embodiment, and the description of the repeated points is omitted.

[0081] like Fig.13 As shown, after the incident light is color-separated by the micro-spectrometer element 101, it is filtered by the color filter 104 just above the pixel. In this case, since the light passes through the color filter 104 after the color separation, the light loss is small, and the light utilization efficiency is improved compared with the color filter only structure of the prior art. On the other hand, since it is necessary to pass through two elements (the micro-spectrometer element 101 and the color filter 104), the light utilization efficiency is reduced compared with the imaging element 600 of the first embodiment. In addition, since the incident light reflects the transmission characteristics of the combined application of the spectral characteristics of the micro-spectrometer element 101 and the filtering characteristics of the color filter 104, the light reaching each pixel is in a state where unnecessary color components have been further excluded. Therefore, compared with the color imaging element 100 ( Figure 1 ) has a significantly improved color reproducibility compared to the image pickup element 600 of the first embodiment. That is, it can be said that the light utilization efficiency and color reproducibility are well balanced.

[0082] As described above, in the configuration of the image pickup element 700 of this embodiment, color information can be acquired with high sensitivity. Furthermore, there is an advantage of improving color reproducibility by the filtering effect achieved by using the color filter 104 in combination. This embodiment is the same as the first embodiment except for the above contents, and has the same effects as those described in the first embodiment, and the same changes can be made.

[0083] The above-described various embodiments and their modifications are merely preferred specific examples of the present invention, and the present invention is not limited thereto, and various modifications can be made.

[0084] In the above-mentioned embodiment, an example assuming SiN or TiO2 as the material of the micro-spectrometric element 101 is shown, but the present invention is not limited to this. For example, when the imaging element 12 is used in the visible light to near-infrared light region with a wavelength of 380 to 1000 nm, materials such as SiN, SiC, TiO2, and GaN with a high refractive index and low absorption loss are suitable for the material of the micro-spectrometric element 101. In addition, for near-infrared light with a wavelength of 800 to 1000 nm, as a material with low loss for these lights, Si, SiC, SiN, TiO2, GaAs, and GaN are suitable. Furthermore, in the near-infrared region of the long wavelength band (communication wavelength is 1.3μm or 1.55μm, etc.), InP and the like can also be used in addition to the above-mentioned materials. Furthermore, when the micro-spectrometric element 101 is formed by bonding and coating, examples of the material include polyimides such as fluorinated polyimide, BCB (benzocyclobutene), photocurable resins, UV epoxy resins, acrylic resins such as PMMA (polymethyl methacrylate), polymers such as all resists, and the like.

[0085] Similarly, in the above-mentioned various embodiments and their variations, examples are shown in which SiO2 and air are assumed as the material of the transparent layer 111, but the present invention is not limited to this. Any material can be used as long as it is a general glass material, SiO2, air, etc., a material with a lower refractive index than the material of the micro-spectrometric element 101 and a low loss to the wavelength of the incident light. In addition, the transparent layer may have a laminated structure including multiple materials.

[0086] In the above-mentioned various embodiments and their variations, the case where the three wavelength ranges of light corresponding to the microscopic spectroscopic element 101 are the three primary colors of red, green, and blue is described, but at least one of the three wavelength ranges may be light of a wavelength other than the three primary colors (e.g., infrared light or ultraviolet light). For example, in the case of configuring a microscopic spectroscopic element 101 corresponding to the two primary colors of red and green, using reference Fig.10 The two types of micro-spectrographic elements 101 described in (a) to (c) can be made by changing the design of the fine structure pattern of the columnar structure of the three types of micro-spectrographic elements 101. For example, the two types of micro-spectrographic elements can be an element having a spectroscopic function of separating R and G light into left and straight light, and an element having a spectroscopic function of separating G and R light into left and straight light. At this time, the pixel D corresponding to red is located below these elements. R and pixel D corresponding to green GThe two pixels are arranged in a two-dimensional array as a color pixel unit adjacent to each other in the x-axis direction. Similarly, two types of micro-spectral elements can also be used: an element having a spectroscopic function that separates the light of G and B into left and straight light, and an element having a spectroscopic function that separates the light of B and G into left and straight light. In this case, under these elements, the pixel D corresponding to green G and pixel D corresponding to blue B These two pixels are arranged in a two-dimensional array as a color pixel unit adjacent to each other in the x-axis direction. Alternatively, two types of micro-spectral splitting elements can be used, one having a spectroscopic function to separate the light of B and R into left and straight light, and one having a spectroscopic function to separate the light of R and B into left and straight light. In this case, the pixel D corresponding to blue is located below these elements. B and pixel D corresponding to red R The two pixels may be arranged in a two-dimensional array as a color pixel unit adjacent to each other in the x-axis direction.

[0087] As mentioned above, although this invention was demonstrated based on the specific embodiment, this invention is not limited to the said embodiment, It is a matter of course that various changes can be made within the range which does not deviate from the summary.

Claims

1. An imaging element, comprising: A pixel array, in which a plurality of pixels including photoelectric conversion elements are arranged in an array on a substrate; a transparent layer formed on the pixel array; and The spectroscopic element array includes a plurality of spectroscopic elements arranged in an array at positions corresponding to each of the plurality of pixels inside or above the transparent layer, wherein: A spectroscopic element is configured for each pixel. Each of the spectroscopic elements includes a plurality of fine structures formed by a material having a refractive index higher than that of the transparent layer, and the plurality of fine structures have a fine structure pattern. Each of the spectroscopic elements separates incident light into deflected light having different propagation directions according to wavelengths and emits the deflected light. The pixel array is arranged at a position for receiving light separated by the plurality of spectroscopic elements in propagation directions according to wavelengths, and the propagation directions according to wavelengths are different between adjacent spectroscopic elements.

2. The imaging element according to claim 1, wherein: Groups of N adjacent beam splitters along a first direction of the beam splitter array are repeatedly arranged along the first direction, and in the groups of N adjacent beam splitters, the fine structure patterns are different from each other, wherein N≥2.

3. The imaging element according to claim 1, wherein: Each of the plurality of light-splitting elements has a constant thickness in a direction in which light of the plurality of microstructures passes.

4. The imaging element according to claim 1, wherein: The thickness of each of the plurality of light-splitting elements in the direction in which light passes through the plurality of fine structures varies depending on the position.

5. The imaging element according to claim 1, wherein: The deflected light that is separated and emitted is incident on adjacent first pixels, second pixels, and third pixels in the plurality of light splitting elements. When the incident light is white light, The light incident on the first pixel has a peak in light intensity in a blue wavelength range below 500 nm. The light incident on the second pixel has a peak of light intensity in a green wavelength range of 500 nm to 600 nm. The light incident on the third pixel has a peak of light intensity in a red wavelength range having a wavelength of 600 nm or more.

6. The imaging element according to claim 2, wherein: N is 3, the microstructure is a columnar structure, and the different microstructure patterns in the group of three light splitting elements include: A first fine structure pattern arranged in the order of a columnar structure having a first width, a columnar structure having a second width, and a columnar structure having a third width in the arrangement direction of the three light splitting elements; A second fine structure pattern arranged in the order of a columnar structure having the third widest width, a columnar structure having the second widest width, and a columnar structure having the first widest width in the arrangement direction of the three light splitting elements; and A third fine structure pattern is arranged in the order of the second widest columnar structure, the first widest columnar structure, and the third widest columnar structure in the arrangement direction of the three light splitting elements.

7. The imaging device according to claim 5, comprising: The filter array has at least one type of filter arranged in an array between the pixel array and the spectroscopic element array.

8. The imaging element according to claim 7, wherein: The filter array is closer to the pixel array than the beam splitting element.

9. A camera device comprising: The imaging element according to any one of claims 1 to 8; An imaging optical system for forming an optical image on an imaging surface of the imaging element; and The signal processing unit processes the electrical signal output by the imaging element.

Images