Color imaging device and imaging device

Abstract

To provide a highly sensitive color imaging device and a highly sensitive imaging device formed by integrating fine spectroscopic elements which can be easily formed, have a smaller polarization dependency, and can separate an incident light into a 3-wavelength region to face a two-dimensional array.SOLUTION: An imaging element 100 is formed by laminating a low refractive-index transparent layer 111 made of SiO2, for example, and a plurality of microlenses 103 on a two-dimensional pixel array in which pixels 102 including photoelectric conversion elements are arranged in the pattern of an array. In the low refractive-index transparent layer 111, a plurality of fine spectroscopic elements 101 are buried, which have the same thickness (the length in the direction perpendicular to the two-dimensional pixel array) and are made of a fine structure including such materials as SiN having a higher index of refraction than that of the transparent layer 111.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a color image sensor and an imaging device equipped with a color image sensor. [Background technology]

[0002] 2. Description of the Related Art In general, in an image sensor having a photoelectric conversion element such as a charge coupled device (CCD) sensor or a complementary metal oxide semiconductor (CMOS) sensor, it is necessary to perform color separation of incident light in order to obtain color information of an imaged subject.

[0003] A cross-sectional view of a conventional color image sensor is shown in Fig. 16. In a conventional color image sensor 600, a photoelectric conversion element 602 is disposed on electrical wiring 601, and a subtractive color filter 604 made of an organic material or an inorganic multilayer film material is disposed opposite each pixel including the photoelectric conversion element 602. A microlens 605 is disposed above the color filter 604.

[0004] When light enters through the microlens 605, a color filter 604 is used to transmit only light of a desired wavelength band and absorb or reflect light of unnecessary wavelength bands, thereby obtaining signals from three photoelectric conversion elements 602 corresponding to red (R), green (G), and blue (B) for each pixel, thereby generating a color two-dimensional image.

[0005] However, in a typical color image sensor 600 as described above, when the incident light has a ratio of 1:1:1 between RGB, the total amount of light after passing through the color filter 604 is inevitably reduced to about 1 / 3. The remaining lost light is lost due to absorption or reflection, and cannot reach the photoelectric conversion element 602. Therefore, the light utilization efficiency of the incident light is at most about 30%, and the sensitivity of the image sensor is significantly limited. In recent years, as pixels have become increasingly miniaturized, the amount of light received by each pixel has decreased, and there is a demand for a solution to the above problem.

[0006] For this reason, it has been proposed to configure a color imaging element using a spectroscopic element such as a microprism or a dichroic mirror that can split the incident light according to the wavelength band, instead of the color filter 604. In principle, this approach can greatly reduce the loss of incident light and greatly improve the light utilization efficiency. However, in recent years, with the miniaturization of pixels, it is difficult to integrate such elements on a photoelectric conversion element.

[0007] In recent years, it has been proposed to configure a color imaging element using a dispersive element made of a fine structure that can be relatively easily integrated on a photoelectric conversion element. Non-Patent Document 1 proposes a method of theoretically eliminating light loss in color separation and improving light utilization efficiency by using two types of fine structures that can separate incident light into two wavelength regions.

[0008] Fig. 17(a) shows a top view of a color imaging element using a conventional spectroscopic element, Fig. 17(b) shows a cross-sectional view taken along line XVIIb-XVIIb of the color imaging element, and Fig. 17(c) shows a cross-sectional view taken along line XVIIc-XVIIc of the color imaging element. As shown in the figure, in a color imaging element 610, incident light is separated into straight light and deflected light according to the wavelength region by fine beam structures 606-1 and 606-2 arranged corresponding to pixels 602 instead of color filters 604. This is because the phase delay effect felt by the incident light in and around the fine beam structures is significantly different in one wavelength region and is almost equal in the other wavelength region.

[0009] Therefore, by arranging two types of fine beam structures 606-1 and 606-2 with different structural thicknesses alternately in each row on the two-dimensional pixel array, it becomes possible for four adjacent photoelectric conversion elements 602 to receive light having different wavelength components. As a result, color information can be generated by matrix calculation using the photoelectric conversion signals output from each photoelectric conversion element 602.

[0010] Furthermore, Non-Patent Document 1 also proposes a color image sensor 620 that improves light utilization efficiency by arranging a step-shaped microstructure 607 capable of separating incident light into three wavelength regions on a pixel 602, as shown in Fig. 18. In addition to generating color information by the above-mentioned matrix operation, this method can cause the separated light in the three wavelength regions to be incident on three adjacent photoelectric conversion elements 602, respectively, and therefore it is considered that color information can be directly generated using the photoelectric conversion signals output from each photoelectric conversion element 602. [Prior art documents] [Non-patent literature]

[0011] [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 Summary of the Invention [Problem to be solved by the invention]

[0012] However, the technique disclosed in Non-Patent Document 1 has practical problems.

[0013] First, in the method using the microstructures 606-1 and 606-2 that separate the incident light into two wavelength regions, the structural heights of the two types of microstructures 606-1 and 606-2 are different, which increases the cost of the manufacturing process. In addition, since the shapes of the microstructures 606-1 and 606-2 are beam-shaped structures with a long axis, the phase delay effect felt by the light differs depending on the polarization direction of the incident light, and there is a problem that the color separation function has polarization dependency. Furthermore, there is a concern about color reproducibility because signal processing is performed from two sets of light intensity data separated into two wavelength regions to restore RGB information.

[0014] On the other hand, according to the method using the step-shaped microstructure 607 that separates the incident light into three wavelength regions, it is true that a color image with high light utilization rate and good color reproducibility can be obtained theoretically, but it is difficult to fabricate the microstructure 607 with ideal spectral characteristics. The disclosed step-shaped microstructure 607 requires multiple lithography and etching processes, and high-precision alignment technology in the lithography process, which increases the fabrication cost. In addition, like the microstructures 606-1 and 606-2 that separate the incident light into two wavelength regions, the shape of the microstructure 607 is a beam-shaped structure with a long axis, so there is a problem that the color separation function has polarization dependency.

[0015] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a highly sensitive color imaging element and imaging device in which a micro-spectroscopic element that is easy to fabricate, has little polarization dependency, and is capable of separating incident light into three wavelength regions is integrated opposite a two-dimensional pixel array. [Means for solving the problem]

[0016] In order to solve the above-mentioned problems, one aspect of the present invention is a color imaging element comprising: a two-dimensional pixel array in which a plurality of pixels, each including a photoelectric conversion element, are arranged in a two-dimensional array on a substrate; a transparent layer formed on the two-dimensional pixel array; and a two-dimensional spectroscopic element array in which a plurality of spectroscopic elements are arranged in a two-dimensional array inside or on the transparent layer, each of the spectroscopic elements including a set of microstructures made of a material having a refractive index higher than the refractive index of the transparent layer, the set of microstructures including a plurality of microstructures having the same length in a vertical direction relative to the two-dimensional pixel array and different shapes in a horizontal direction relative to the two-dimensional pixel array, the microstructures being arranged at intervals equal to or less than the wavelength of the incident light, and at least a portion of the light incident on the spectroscopic element is separated into first to third polarized light beams having different propagation directions depending on the wavelength, the first to third polarized light beams exiting the spectroscopic element and being incident on three of the pixels arranged consecutively in one direction of the two-dimensional pixel array, respectively.

[0017] In another aspect of the present invention, the microstructure is a columnar structure whose bottom and top surfaces have a four-fold rotational symmetry shape with the center as the axis of symmetry.

[0018] In another aspect of the present invention, the first to third deflected light beams are incident on first to third photoelectric conversion elements of three adjacent consecutive pixels, respectively.

[0019] In another aspect of the present invention, when the incident light is white light, the light incident on the first photoelectric conversion element has a peak of light intensity in a blue wavelength region of 500 nm or less, the light incident on the second photoelectric conversion element has a peak of light intensity in a green wavelength region of 500 nm to 600 nm, and the light incident on the third photoelectric conversion element has a peak of light intensity in a red wavelength region of 600 nm or more.

[0020] In another aspect of the present invention, the shape of the set of microscopic structures is the same for all of the dispersing elements constituting the two-dimensional dispersing element array.

[0021] In another aspect of the present invention, the orientation of the set of microstructures of adjacent dispersive elements arranged along a first direction of the two-dimensional dispersive element array is alternately inverted, three adjacent consecutive pixels are arranged along the first direction, and of the three adjacent pixels along the first direction, the two outermost pixels receive any of the first to third polarized light beams from two adjacent dispersive elements along the first direction.

[0022] In another aspect of the present invention, the two-dimensional pixel array and the two-dimensional spectroscopic element array are further provided with a color filter array in which at least one of a first color filter having a transmittance peak in a blue wavelength range of 500 nm or less, a second color filter having a transmittance peak in a green wavelength range of 500 nm to 600 nm, and a third color filter having a transmittance peak in a red wavelength range of 600 nm or more is arranged in an array.

[0023] Another aspect of the present invention is an imaging device comprising a color imaging element of one aspect of the present invention, an imaging optical system for forming an optical image on an imaging surface of the color imaging element, and a signal processing unit for processing an electrical signal output by the color imaging element. Effect of the Invention

[0024] According to the present invention, by using a microspectroscopic element that is easy to fabricate, has little polarization dependency, and is capable of separating incident light into three wavelength regions, it is possible to fabricate a color imaging element and imaging device with high light utilization efficiency more easily than before. [Brief description of the drawings]

[0025] [Figure 1] 1 is a side view showing a schematic configuration of an imaging device according to the present invention. [Diagram 2] 1 is a diagram showing a schematic view of a part of a cross section of a pixel array and a dispersive element array of an image sensor according to a first embodiment of the present invention. [Diagram 3] FIG. 1A is a top view showing a schematic configuration of a portion of an image sensor according to a first embodiment of the present invention, and FIG. [Figure 4] FIG. 1A is a top view of a columnar structure constituting a microspectroscopic element of an image sensor according to a first embodiment of the present invention, and FIG. [Diagram 5] FIG. 2A is a cross-sectional view of an example of a micro-spectral element of the image sensor according to the first embodiment of the present invention, and FIG. 2B is a diagram showing the phase delay distribution of each of three wavelengths separated by the micro-spectral element. [Figure 6] FIG. 1A is a top view of an example of a micro-spectral element of an image sensor according to a first embodiment of the present invention, and FIG. [Figure 7] FIG. 1(a) is a diagram showing the wavelength dependence of the efficiency of parallel light with vertical polarization being separated and propagated in three directions from the exit end of a micro-spectroscopic element when parallel light with vertical polarization is incident on the top surface of a columnar structure in an imaging element according to embodiment 1 of the present invention, and FIG. 1(b) is a diagram showing the wavelength dependence of the efficiency of parallel light with horizontal polarization being separated and propagated in three directions from the exit end of a micro-spectroscopic element when parallel light with horizontal polarization is incident on the top surface of a columnar structure. [Figure 8] 1(a) to 1(h) are diagrams illustrating examples of structural patterns of micro dispersing elements of an image pickup device according to a first embodiment of the present invention. [Figure 9] 1(a) to 1(c) are diagrams illustrating schematic arrangements of pixels corresponding to color components of an image sensor according to a first embodiment of the present invention. [Figure 10] 1(a) to 1(c) are diagrams illustrating schematic arrangements of pixels corresponding to color components of an image sensor according to a first embodiment of the present invention. [Figure 11] 1 is a cross-sectional view showing a schematic configuration of an image sensor according to a modified example of the first embodiment of the present invention. [Figure 12] FIG. 10(a) is a top view showing a schematic configuration of a portion of an image sensor according to a second embodiment of the present invention, and FIG. [Figure 13] FIG. 11 is a diagram illustrating a schematic arrangement of pixels in an image sensor according to a second embodiment of the present invention. [Figure 14]FIG. 11(a) is a top view showing a schematic configuration of a part of an image sensor according to a third embodiment of the present invention, and FIG. [Figure 15] FIG. 11(a) is a top view showing a schematic configuration of a part of an image sensor according to a fourth embodiment of the present invention, and FIG. [Figure 16] FIG. 1 is a cross-sectional view of a conventional color imaging element. [Figure 17] 1A is a top view of a color imaging element using a conventional dispersive element, FIG. 1B is a cross-sectional view taken along line XVIIb-XVIIb of FIG. 1A, and FIG. 1C is a cross-sectional view taken along line XVIIc-XVIIc of FIG. [Figure 18] FIG. 11 is a cross-sectional view of another color imaging element using a conventional spectroscopic element. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, it goes without saying that the following embodiments are merely examples and the present invention is not limited to these embodiments.

[0027] 1 is a side view showing a schematic configuration of an imaging device of the present invention. The imaging element 10 includes a lens optical system 11, an imaging element 12 including a photoelectric conversion element such as a CCD or a CMOS, and a signal processing unit 13 that processes a photoelectric conversion signal output from the imaging element 12 to generate an image signal.

[0028] Light such as natural light or illumination light is incident on object 1, and the light that is transmitted / reflected / scattered or emitted from object 1 forms an optical image on image sensor 12 by lens optical system 11. Generally, lens optical system 11 is composed of a lens group made up of multiple lenses lined up along an optical axis to correct various optical aberrations, but in Fig. 1 it is shown as a single lens for the sake of simplicity. In addition, signal processing unit 13 has an image signal output that sends the generated image signal to the outside.

[0029] The imaging device 10 of the present invention may include known components such as an infrared light blocking optical filter, an electronic shutter, a viewfinder, a power source (battery), a flashlight, etc., but the description of these is omitted since they are not particularly necessary for understanding the present invention. Also, the above configuration is merely an example, and in the present invention, known elements can be used in appropriate combination for the components other than the lens optical system 11, the imaging element 12, and the signal processing unit 13.

[0030] Before describing specific embodiments of the present invention, an overview of the image sensor 12 in the embodiment of the present invention will be given.

[0031] The image sensor 12 according to the embodiment of the present invention includes a pixel array in which a plurality of cells (pixels) 102 including photoelectric conversion elements are arranged two-dimensionally, and a spectroscopic element array in which a plurality of micro-spectroscopic elements 101 are arranged two-dimensionally. FIG. 2 is a diagram showing a schematic view of a part of a cross section of the pixel array and the spectroscopic element array of the image sensor according to the embodiment 1 of the present invention. The spectroscopic element array faces the pixel array, and is disposed on the side where light from the lens optical system is incident. Each micro-spectroscopic element 101 is composed of a plurality of columnar structures having a uniform thickness. Note that, for convenience, the micro-spectroscopic elements 101 are represented by four columnar structures, but there is no limit to the number, intervals, or arrangement pattern, and various arrangement forms may be adopted.

[0032] Visible light components contained in the light incident on the imaging element 12 are classified into a first color component, a second color component, and a third color component for each wavelength region. The combination of the first to third color components is generally a combination of the three primary colors of red (R), green (G), and blue (B), but is not limited to this as long as it divides the light into three wavelength regions.

[0033] The micro-spectroscopic element 101 in the embodiment of the present invention has a function of changing the propagation direction of the incident light according to the above-mentioned first to third color components by utilizing the phase delay effect and its structural dimension dependency and wavelength dependency described later, and spatially separating the light on the pixel array. That is, in the embodiment of the present invention, at least a part of the light incident on the image sensor has its propagation direction changed by the micro-spectroscopic element 101 according to the color component, and is incident on a plurality of pixels 102. Therefore, by appropriately setting the distance between the micro-spectroscopic element 101 and the pixels 102, it is possible to receive the light separated into three wavelength ranges at different pixels 102.

[0034] When light is incident on a pixel 102, the photoelectric conversion element outputs an electrical signal (photoelectric conversion signal) according to the intensity of the incident light, so that a signal (color information) according to a color component can be obtained directly or by using signal calculation. Since the above-mentioned micro-spectroscopic elements 101 and the multiple pixels 102 corresponding to the micro-spectroscopic elements 101 are arranged two-dimensionally, color information of the optical image of an object formed by the lens optical system 11 can be obtained.

[0035] In the embodiments 1 and 2 described below, by using a microlens array, almost all of the incident light passes through any one of the micro spectroscopic elements 101 constituting the spectroscopic element array, and almost all of the incident light is separated into three wavelength ranges and enters the pixel array. Therefore, color information can be obtained directly from the photoelectric conversion signal or by using a simple calculation.

[0036] In the third and fourth embodiments described below, a portion of the incident light passes through the micro-spectroscopic elements 101 that constitute the spectroscopic element array, and thus the portion of the incident light is separated into three wavelength regions before entering the pixel array. Therefore, a portion of each pixel 102 outputs a photoelectric conversion signal according to the combined light intensity of the light separated into the three wavelength regions and the light not separated. Color information can be obtained by applying an appropriate matrix operation described below to the output photoelectric conversion signal.

[0037] According to the image sensor 12 in the embodiment of the present invention, color information can be obtained by light separation into three colors with low loss using the micro-spectroscopic element 101 without using a subtractive color filter. Therefore, compared with an image sensor using a color filter, the total amount of light reaching the pixel array can be increased, and the imaging sensitivity can be improved. Furthermore, since the micro-spectroscopic element 101 is composed of a structure with a constant thickness that is easy to fabricate, and does not have polarization dependency due to the symmetry of the top and bottom surfaces of the structure, the problem of the color separation function having polarization dependency in the conventional technology disclosed in Non-Patent Document 1 can be solved.

[0038] Hereinafter, more specific embodiments of the present invention will be described with reference to the drawings.

[0039] (Embodiment 1) The configuration of the image sensor according to the first embodiment will be outlined below.

[0040] FIG. 3(a) is a top view of a schematic configuration of a part of an image sensor according to the first embodiment of the present invention, and FIG. 3(b) is a cross-sectional view thereof. In the image sensor 100 according to the first embodiment, a low-refractive-index transparent layer 111 made of SiO2 or the like and a plurality of microlenses 103 are laminated on a two-dimensional pixel array in which pixels 102 including photoelectric conversion elements are arranged in an array. Inside the low-refractive-index transparent layer 111, a micro-spectroscopic element 101 made of a plurality of microstructures having a constant thickness (length in a direction perpendicular to the two-dimensional pixel array) formed of a material such as SiN having a refractive index higher than that of the transparent layer 111 is embedded. For convenience, in the following description, an xyz Cartesian coordinate system is set in which the normal direction of the two-dimensional pixel array is the z-axis, the direction parallel to the two-dimensional pixel array in which the three pixels 102 constituting the pixel unit 110 are arranged is the x-axis, and the direction parallel to the two-dimensional pixel array and perpendicular to the x-axis is the y-axis.

[0041] As shown in the figure, the microlenses 103, the micro-spectroscopic elements 101, and the pixels 102 are arranged in a lattice pattern on the xy plane, and one micro-spectroscopic element 101 is arranged on the central axis of each microlens 103. If three pixels adjacent in the x-axis direction are considered to be one pixel unit 110, each microlens 103 adjacent in the x-axis direction corresponds one-to-one with the pixel unit 110, and the central axis of each microlens 103 passes through approximately the center of the central pixel 102 of the corresponding pixel unit. In other words, one microlens 103 and one micro-spectroscopic element 101 correspond to three pixels 102 adjacent in the x-axis direction, and if the above-mentioned microlenses 103, the micro-spectroscopic elements 101, and the pixel unit 110 are considered to be one image sensor unit, the image sensor unit is arranged in a lattice pattern on the xy plane.

[0042] In the above description, a two-dimensional pixel array arranged in an orthogonal lattice pattern has been described as an example, but the arrangement, shape, size, etc. of the pixels 102 are not limited to the example shown in this figure, and any known arrangement, shape, and size may be used. In addition, although omitted in Figures 3(a) and (b), a high-refractive index uneven structure made of SiN or the like may be provided between the two-dimensional pixel array and the microstructure, which operates as an internal microlens and guides light from the microspectroscopic element 101 to the photoelectric conversion element in the pixel 102. The structure shown in Figures 3(a) and (b) can be manufactured by known semiconductor manufacturing techniques.

[0043] Note that the imaging element 100 shown in Figures 3(a) and (b) has a back-illuminated structure in which light is received from the opposite side of the wiring layer 112, but this embodiment is not limited to such a structure and may have a front-illuminated structure in which light is received from the wiring layer 112 side.

[0044] The function of each component of the image sensor 100 in this embodiment will be described below.

[0045] White light incident on the image sensor 100 is first collected by the microlens array, and almost all of the light passes through the micro-spectroscopic elements 101 corresponding to each microlens 103. Each micro-spectroscopic element 101 spatially separates the light into three wavelength regions in the xz plane, and each of the light is received by three pixels 102 directly below each micro-spectroscopic element 101. In the example shown in FIG. 3(b), each micro-spectroscopic element 101 propagates the first color component light (R) in a first direction (right), the second color component light (G) in a second direction (straight), and the third color component light (B) in a third direction (left). Therefore, the three pixels 102D directly below each micro-spectroscopic element 101 are separated by a first wavelength region (R), a second wavelength region (G), and a third wavelength region (B) in a third direction (left). R (right), D G (Center), D B (Left) corresponds to detection of R, G, and B color information, respectively.

[0046] The above is just an example. Depending on the configuration of each micro-spectroscopic element 101, the combination of color components and propagation directions can be freely changed. Accordingly, the pixels 102D corresponding to each of RGB can be changed. R , D G , D B will also be changed.

[0047] When the light spatially separated into three wavelength regions is received by each of the three pixels 102, photoelectric conversion is performed by the photoelectric conversion element in each pixel 102, and an image signal including color information is output.

[0048] In addition, the three pixels 102D directly below each microspectroscopic element 101 R , D G , D B Width in the x-axis direction w d1 , w d2 , w d3 may be the same or different. Accordingly, the width w lx and the width in the y-axis direction w ly In the example of FIG. 3, three pixels 102D R , D G , D B Width in the x-axis direction w d1 , w d2 , wd3 are the same, and the microlens 103 is w lx And w ly are different.

[0049] In addition, a high refractive index uneven structure made of SiN or the like that acts as an internal microlens may be provided between the pixel unit 110 and the microspectroscopic element 101. However, since the microspectroscopic element 101 described later can have a lens function depending on the phase delay distribution it forms, it is also possible to omit the internal microlens.

[0050] The microspectroscopic element according to this embodiment will be described below.

[0051] The micro-spectroscopic element 101 in the first embodiment is composed of a plurality of fine columnar structures 121. Fig. 4(a) is a top view of the columnar structures constituting the micro-spectroscopic element of the image sensor according to the first embodiment of the present invention, and Fig. 4(b) is a cross-sectional view thereof. The columnar structures 121 are formed of a material such as SiN having a refractive index n1 higher than the refractive index n0 of the transparent layer 111, and the thickness h of the structure is constant.

[0052] The bottom and top surfaces of the columnar structure 121 are square. The columnar structure 121 functions as an optical waveguide that confines and propagates light within the structure due to the difference in refractive index with the transparent layer 111. Therefore, when light is incident from the top side, the light propagates while being strongly confined within the columnar structure 121, and the effective refractive index n eff Specifically, when the phase of light propagating through the transparent layer 111 a length equivalent to the thickness of the columnar structures 121 is taken as a reference, the amount of phase delay φ caused by the columnar structures 121 is expressed as follows, where λ is the wavelength of light in a vacuum: φ=(n eff -n0)×2πh / λ (1) It is represented by. Since this amount of phase delay varies depending on the wavelength λ of light, different amounts of phase delay can be given to the light incident on the same columnar structure 121 according to the wavelength range (color component). Further, since the bottom and top surfaces of the columnar structure 121 are square, there is no change in the optical properties including the phase delay effect even when the polarization direction is changed. Furthermore, n eff is known to be a function of the structural dimensions, and n0 < n eff < takes the value of n1. Therefore, in the examples shown in FIGS. 4(a) and 4(b), it is possible to set an arbitrary amount of phase delay by changing the width w of the columnar structure 121.

[0053] The cross-sectional view of FIG. 5(a) is an example of the micro-spectroscopic element 101 in the first embodiment, which is configured by arranging two of the above-described columnar structures 121-1 and 121-2 in the x-axis direction. In the y-axis direction, a plurality of the above-described columnar structures 121-1 and 121-2 are arranged at intervals less than the wavelength.

[0054] As shown in FIG. 5(a), the widths w of the adjacent columnar structures 121-1 and 121-2 in the x-axis direction are different. Due to this difference in width w, it is possible to give different phase delay distributions for each wavelength region to the light transmitted through the micro-spectroscopic element 101, and the light wavefront can be changed. Since the propagation direction (deviation direction) of light is determined by this light wavefront, it is possible to spatially separate the light transmitted through the micro-spectroscopic element 101 according to the wavelength range (color component). That is, the micro-spectroscopic element 101 in the first embodiment arranges a plurality of columnar structures 121 and changes the dimension w in the plane orthogonal to the light propagation direction of the adjacent columnar structures 121-1 and 121-2, thereby giving different light wavefronts according to the wavelength region of the incident light and spatially separating the color components.

[0055] For example, in the case of the structure shown in FIG. 5(a), different phase delay distributions can be given according to three wavelengths (for example, wavelengths corresponding to RGB) as shown in FIG. 5(b). In this example, the phase delay distribution of the wavelength corresponding to the first color component light (R) is along a straight line where the phase amount increases linearly from 0 to +2π, the phase delay distribution of the wavelength corresponding to the second color component light (G) has no spatial change, and the phase delay distribution of the wavelength corresponding to the third color component light (B) is along a straight line where the phase amount decreases linearly from 0 to -2π. In this case, the light transmitted through the micro-spectroscopic element 101 can efficiently propagate in the first direction (right) for the first color component light (R), in the second direction (straight) for the second color component light (G), and in the third direction (left) for the third color component light (B), as shown in FIG. 5(a).

[0056] The above description is merely an example, and the combination of color components and deflection directions can be freely changed depending on the dimensions of each columnar structure 121. For example, the first color component light (R) can be efficiently propagated in the second direction (straight), the second color component light (G) in the first direction (right), and the third color component light (B) in the third direction (left).

[0057] A more detailed example of the microspectroscopic element 101 in this embodiment will be described.

[0058] Fig. 6(a) is a top view of an example of a micro-spectroscopic element of an image sensor according to the first embodiment of the present invention, and Fig. 6(b) is a cross-sectional view thereof. Two columnar structures 121-1, 121-2 with different widths w1, w2 and a constant thickness (length in the direction perpendicular to the two-dimensional pixel array) are arranged in the x-axis direction, and three identical columnar structures 121-1, 121-2 are arranged in the y-axis direction, forming one micro-spectroscopic element 101. Note that the columnar structures 121-1, 121-2 are assumed to be made of SiN (n1 = 2.03), the transparent layer is assumed to be made of SiO2 (n0 = 1.45), and the bottom and top surfaces are assumed to be square. In addition, the thickness h of all of the columnar structures 121-1, 121-2 was 1200 nm, the width w1 of the columnar structure 121-1 on the left side of the pattern was 145 nm, the width w2 of the columnar structure 121-2 on the right side of the pattern was 340 nm, and the spacing p between the columnar structures 121-1, 121-2 in the x-axis and y-axis directions was 450 nm.

[0059] 7(a) and (b) show the wavelength dependence (calculation results based on strict coupled wave theory) of the efficiency (ratio of light intensity in each propagation direction to the incident light intensity) of the splitting and propagation from the output end of the micro-spectroscopic element 101 in three directions (R, G, and B directions in FIG. 6(b)) when parallel light is incident from the top surfaces of the columnar structures 121-1 and 121-2 in the above-mentioned structure. FIG. 7(a) shows the result when vertically polarized light in FIG. 6(a) is incident, and FIG. 7(b) shows the result when horizontally polarized light in FIG. 6(a) is incident. In addition, in the calculation, it was assumed that the above-mentioned micro-spectroscopic 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 a single micro-spectroscopic element 101. In addition, the deflection angles θ in each of the three directions are R , θ G , θ B is based on the diffraction of light, R: sinθ R = λ / P, G:θ G =0 (straight ahead), B: sinθ B = λ / P.

[0060] The characteristics shown in Figs. 7(a) and (b) correspond to the spectral sensitivity characteristics of color filters in a conventional imaging device. The results shown in Figs. 7(a) and (b) show that the efficiency in the first direction (R) peaks in the red wavelength region of 600 nm or more, the efficiency in the second direction (G) peaks in the green wavelength region of 500-600 nm, and the efficiency in the third direction (B) peaks in the blue wavelength region of 500 nm or less. In addition, good spectral performance of 40-60% is shown, and the characteristics do not show significant polarization dependence. The sum of the curves R, G, and B, i.e., the total transmittance, is 95% or more, and there is almost no light loss due to scattering or reflection.

[0061] The above results show that the use of the micro-spectroscopic element 101 in the first embodiment enables highly efficient spatial separation of color components. Furthermore, in the above example, the size of the single micro-spectroscopic element 101 is 1.35 μm square, which is equivalent to the minimum pixel size of general CCD and CMOS sensors. Therefore, it is possible to form a micro-spectroscopic element 101 corresponding to a pixel unit 110 having a minimum pixel size. It is also possible to form micro-spectroscopic elements 101 of different sizes depending on the size, number, and arrangement pattern of the columnar structures 121.

[0062] It is possible to provide desired spectral characteristics by appropriately designing the material, number, shape, size, arrangement pattern, etc. of the columnar structures 121 constituting the microspectroscopic element 101. As a result, as described above, it is possible to separate and cause only light in a desired wavelength range to enter each photoelectric conversion element, and a signal corresponding to a color component can be obtained from the photoelectric conversion signal output from each photoelectric conversion element.

[0063] As described above, since there is almost no light loss due to the micro-spectroscopic elements 101, the total amount of light reaching the pixel array can be dramatically increased compared to an imaging element using a color filter of the prior art, and imaging sensitivity can be improved. Even if the spectroscopic performance of each micro-spectroscopic element 101 differs slightly from the above-mentioned ideal performance, it is possible to obtain good color information by correcting and calculating the acquired signal according to the degree of the difference in performance.

[0064] In addition, in arranging the columnar structures 121 described above, it is preferable to arrange them at intervals equal to or less than the wavelength of light in order to prevent the generation of unnecessary diffracted light due to the periodic structure.

[0065] In the above example, the case where the bottom and top surfaces of the columnar structure are square has been described, but the shape is not limited to this. In other words, as long as the surface has a shape that is four-fold rotationally symmetric with respect to an axis passing through the center of the bottom and top surfaces, the spectroscopic function does not depend on the polarization, and the operation as an optical waveguide that brings about a phase delay effect is not lost. Therefore, it is preferable to adopt a columnar structure having a surface that is four-fold rotationally symmetric, such as a square, a hollow square, a circle, a hollow circle, or a cross shape, as shown in Figures 8(a) to (h).

[0066] In order for the spatial light distributions on the pixel unit 110 to be sufficiently separated from one another after separation of color components by the micro spectroscopic element 101, it is preferable that the distance between the output end of the micro spectroscopic element 101 and the photoelectric conversion element of the pixel 102 is 1 μm or more. On the other hand, in order to make the imaging element 100 thinner and to save on material costs and process time, it is preferable that the distance between the output end of the micro spectroscopic element 101 and the photoelectric conversion element of the pixel 102 be as short as possible.

[0067] Furthermore, in this case, since it is necessary for each spatial distribution of light on the pixel unit 110 to be clearly separated from each other according to the color component over a short propagation distance, it is preferable to greatly tilt the wavefront of the light by the micro-spectroscopic element 101 to increase the deflection (bending) angle. In order to increase the deflection angle, it is suitable for the phase delay distribution in each wavelength range formed by the micro-spectroscopic element 101 to vary from 0 to 2π, so it is preferable that the variable range of the phase delay amount by the columnar structures 121 is 2π or more in each wavelength range. Therefore, from formula (1), the desired center wavelength in the wavelength range on the longest wavelength side of the wavelength ranges to be separated is λ r Then, the thickness h of the columnar structure 121 is expressed as h=λ r It is desirable to set it to the vicinity of / (n1-n0).

[0068] The microspectroscopic element 101 having the spectroscopic function described above can be fabricated by performing thin film deposition and patterning using known semiconductor manufacturing techniques. The microspectroscopic element 101 of the present embodiment 1 is composed of a plurality of columnar structures 121 with a uniform thickness, and therefore can be fabricated more inexpensively and easily than the step-like structure disclosed in Non-Patent Document 1.

[0069] The arrangement of the micro-optical elements and pixels in the image sensor of this embodiment will be described below.

[0070] In the example shown in Fig. 3, the rows of the micro light-splitting elements 101 arranged along the x-axis direction are repeatedly arranged along the y-axis direction without being shifted in the x-axis direction, and as a result, the patterns of the micro light-splitting elements 101 are continuously arranged along the y-axis direction. In this case, in the x-axis direction, three pixels 102D corresponding to the color components directly below each micro light-splitting element 101 are arranged in a row. B , D G , D R are arranged in this order from left to right, and this order is repeated.

[0071] Similarly, for the pixels 102, a row of the pixels 102 arranged along the x-axis direction is repeatedly arranged along the y-axis direction without being shifted in the x-axis direction, so that three pixels 102D B , D G , D R are arranged consecutively.

[0072] 9(a) to 9(c) are schematic diagrams showing the arrangement of pixels corresponding to color components in the image sensor according to the first embodiment of the present invention. B , D G , D R Assuming that one color pixel unit U is a color pixel unit U, the color pixel unit U1 shown in FIG. 9(a) and the color pixel unit U2 shifted by a single pixel in the x-axis direction from the color pixel unit U1 each include one pixel each corresponding to R, G, and B. That is, by acquiring color information while shifting the color pixel unit U by a single pixel in the xy plane, information on the three colors of RGB can be obtained by approximately the number of pixels. This means that the resolution of the image sensor can be increased to the extent of the number of pixels (equivalent to the so-called Bayer arrangement). Therefore, the image sensor of the present embodiment 1 is not only highly sensitive, but also capable of generating color information at high resolution of a single pixel size.

[0073] The arrangement of the micro-optical elements and pixels that realize the above-mentioned single pixel size resolution is not limited to that shown in Fig. 9(a) and can be changed in various ways. Fig. 9(b) and Fig. 9(c) show another example, in which the rows of the micro-spectroscopic elements 101 and color pixel units U arranged along the x-axis direction are sequentially arranged in the y-axis direction while shifting in the x-axis direction by one pixel size in Fig. 9(b) and by two pixel sizes in Fig. 9(c). With such an arrangement, color information can be generated with a single pixel size resolution, as in Fig. 9(a).

[0074] 10(a) to (c) show examples of arrangements different from those in FIG. 9(a) to (c), in which 3 pixels D B , DG , D R The order of the pixels is reversed, and the shift in the x-axis direction is the same as in Figs. 9(a) to (c) above. In this case, too, color information can be generated with a resolution of a single pixel size, as in Fig. 9(a). B , D G , D R In order to reverse the order, a pattern in which the columnar structures 121-1 and 121-2 of the microspectroscopic element 101 described above are reversed left to right on the x-axis may be used.

[0075] In the pixel arrangement shown in the above-mentioned FIGS. 9(a) to (c) and 10(a) to (c), the first color component light (R) propagates in a first direction (right), the second color component light (G) propagates in a second direction (straight), and the third color component light (B) propagates in a third direction (left) depending on the function of each micro-spectral element 101. R (right), D G (Center), D B The (left) and (right) are assumed to correspond to detection of color information of R, G, and B, respectively. As described above, depending on the configuration of the micro-spectroscopic element 101, the pixel 102 directly below the micro-spectroscopic element 101 may correspond to one of the three RGB colors, but basically, only the order within the color pixel unit U is changed. Even in such a case, if the arrangement is set according to the arrangement rules for the color pixel unit U shown in Figures 9 and 10, color information can be generated at a resolution of the single pixel size in the same way.

[0076] The above description has been given of the image sensor 100 using only the microspectroscopic element 101. Next, a modified example in which a subtractive color filter is also used will be described.

[0077] Fig. 11 shows a cross-sectional view of a schematic configuration of an image sensor according to a modified example of the first embodiment of the present invention. The difference from Fig. 3 is that color filters 104 corresponding to the colors of the pixels 102 are arranged above the pixels 102 corresponding to the color components, and the rest is the same. With this configuration, the light utilization efficiency is improved and color reproducibility is also improved compared to the conventional configuration using only color filters.

[0078] For example, from FIG. 7, the spectral efficiency of the micro-spectroscopic element 101 for RGB is 40 to 60%. Also, the transmittance (spectroscopic efficiency) of the RGB color filter 104 in the corresponding wavelength range is 90%. Assume that the incident light has an intensity ratio of RGB 1:1:1. In this case, in a configuration in which the micro-spectroscopic element 101 and the color filter 104 are used in combination, the light passes through both and enters the pixel, so the total amount of light intensity reaching the three RGB pixels 102 is 36 to 54%. Furthermore, the spectral performance of the micro-spectroscopic element 101 and the color filter 104 is multiplied, and the light enters each pixel 102 with unnecessary color components removed, so that the color reproducibility is greatly improved. On the other hand, in a configuration in which only the color filter 104 is used, the total amount of light intensity reaching the three pixels 102 is 30%, and the color reproducibility is also poorer than that of a configuration in which both are used. Therefore, by using a configuration in which the micro-spectroscopic element 101 and the color filter 104 are used in combination, it is expected that the sensitivity will be improved by 1.2 to 1.8 times compared to a configuration in which only a conventional color filter is used, while the color reproducibility is improved. Note that, although the light utilization efficiency is lower than that of a configuration in which only the micro-spectroscopic element 101 is used, the color reproducibility is significantly improved, so that this modified example of the first embodiment can be said to be a configuration in which the light utilization efficiency, i.e., the sensitivity and color reproducibility are well balanced.

[0079] (Embodiment 2) Next, an image sensor according to a second embodiment of the present invention will be described.

[0080] Fig. 12(a) is a top view of a schematic configuration of a part of an image sensor according to embodiment 2 of the present invention, and Fig. 12(b) is a cross-sectional view thereof. As shown in Figs. 12(a) and 12(b), an image sensor 300 according to embodiment 2 and an image sensor using the same are different from embodiment 1 in that the orientations of the structure patterns of the multiple microspectroscopic elements 101 arranged along the x-axis direction are alternately inverted.

[0081] In addition, the rows of the micro-spectroscopic elements 101 and the color pixel units U arranged along the x-axis direction are sequentially arranged in the y-axis direction while shifting in the x-axis direction by two pixel sizes, and as a result, the orientation of the structure pattern of the micro-spectroscopic elements 101 is also alternately inverted in the y-axis direction. Furthermore, among three pixels 102 adjacent to each other along the x-axis direction that receive light dispersed by one micro-spectroscopic element 101, the two outermost pixels 102 also receive light dispersed by the other two adjacent micro-spectroscopic elements 101, which is also different. The other components of the second embodiment are the same as those of the first embodiment. Below, the differences from the first embodiment will be mainly described, and the overlapping points will not be described.

[0082] As shown in FIG. 12B, the orientation of the structure pattern of the micro-spectral elements 101 is alternately inverted along the x-axis direction, so that the combinations of color components and deflection directions are alternately reversed. Accordingly, the pixels 102 corresponding to the color components immediately below each micro-spectral element 101 are arranged in the order of D from the left. R , D G , D B , D G , D R , D G , D B .... Directly below each micro-spectroscopic element 101 is a pixel 102D. G are arranged, and the pixels 102D on both sides of the R Or D B Also receives the light dispersed by the two adjacent micro-dispersing elements 101 .

[0083] White light incident on the image sensor 300 is first collected by the microlens array, and almost all of the light passes through the micro-spectroscopic elements 101 corresponding to each microlens 103. The light is spatially separated into three wavelength regions in the xz plane by each micro-spectroscopic element 101, and is received by three pixels 102 corresponding to each micro-spectroscopic element 101. At this time, the pixel 102 (D G Pixels 102 (D R , D B ) also receives light propagating from the two adjacent micro-spectroscopic elements 101, but receives light in the same wavelength range due to the inversion of the structural pattern.

[0084] The above is just one example, and the combination of color components and propagation directions can be freely changed depending on the configuration of each micro-spectroscopic element 101, and the pixels 102 corresponding to each of RGB are also changed accordingly. When the light spatially separated into three wavelength regions in this way is received by each of the three pixels 102, photoelectric conversion is performed by the photoelectric conversion element in each pixel 102, and an image signal including color information is output.

[0085] FIG. 13 is a schematic diagram showing the arrangement of pixels in an image sensor according to a second embodiment of the present invention. R , 2 D G , and one D B The four pixels 102 including the four pixels 102 are regarded as one color pixel unit U. In this case, even if a single pixel is shifted in the x-axis direction or the y-axis direction with respect to the color pixel unit U1 shown in the figure, one D R , 2 D G , and one D B In other words, by acquiring color information while shifting the color pixel unit U by a single pixel in the xy plane, information on the three colors of RGB can be obtained by approximately the number of pixels. This means that the resolution of the image sensor can be increased to the extent of the number of pixels. Therefore, the image sensor 300 of the second embodiment is not only highly sensitive, but also capable of generating color information at high resolution of a single pixel size.

[0086] As described above, the configuration of the present embodiment 2 can achieve the same functions as those of the embodiment 1. Moreover, the present embodiment 2 is similar to the embodiment 1 except for the differences from the above embodiment 1, and the common components have the same effects as those described in the embodiment 1, and the same modifications are possible.

[0087] (Embodiment 3) Next, an image sensor according to a third embodiment of the present invention will be described.

[0088] Fig. 14(a) is a top view of a schematic configuration of a part of an image sensor according to embodiment 3 of the present invention, and Fig. 14(b) is a cross-sectional view thereof. As shown in Figs. 14(a) and (b), an image sensor 400 and an image sensor according to embodiment 3 are different from embodiment 1 in that microlenses are arranged in one-to-one correspondence with each pixel. Also, they are different in that matrix calculations using photoelectric conversion signals from each pixel 102 are used to obtain color information. The other components are the same as those of embodiment 1. The following description will focus on the differences from embodiment 1, and overlapping points will not be described.

[0089] 14(b), the microlenses 103 are arranged in one-to-one correspondence with the pixels 102. Accordingly, of the white light incident on the image sensor 400, the light that is incident on each micro-spectroscopic element 101 and color-separated is only the light focused by the micro-lenses 103 located directly above the micro-spectroscopic element 101, and the other light passes through each micro-lens 103 and directly enters the pixel directly below each micro-lens.

[0090] Here, if the intensity of the white light incident on a single microlens 103 is represented by W, and the intensities of the three RGB colors that make up the white light are R, G, and B, respectively, then the white light is incident on the pixel 102D via the three microlenses 103. R , D G , D BThe light incident on each pixel 102D has an intensity represented by W+R, G, and W+B. The above is just an example, and depending on the configuration of each micro-spectroscopic element 101, the combination of color components and propagation directions can be freely changed. R , D G , D B The composition of the color components incident on each of the pixels 102D is also changed. R , D G , D B We will describe how color information is obtained by matrix calculation when light of intensities W+R, G, and W+B is incident on the micro-spectroscopic element 101, but it goes without saying that the numerical values ​​of the matrix operator can be changed depending on the configuration and spectroscopic performance of the micro-spectroscopic element 101.

[0091] The light of intensities W+R, G, and W+B incident on each pixel 102 is photoelectrically converted by a photoelectric conversion element and output as a photoelectric conversion signal. Here, the photoelectric conversion signals corresponding to the light intensities of the three colors RGB and the white light W are S R , S G , S B , S W The photoelectric conversion signals output by the pixels 102 on which light of intensities W+R, G, and W+B is incident are respectively represented as S W+R , S G , S W+B In addition, S W is S W =S R +S G +S B It is represented by S W+R , S W+B are respectively, S W+R =S W +S R , S W+B =S W +S B In addition, the pixel 102D G Since the light incident on the target is a G component split by the micro spectroscopic element 101, the light is G is output as is.

[0092] From the above, S R , S G, S B is the following S W+R , S G , S W+B It can be obtained by matrix calculation using

[0093]

number

[0094] Therefore, for each pixel D R , D G , D B Three photoelectric conversion signals S W+R , S G , S W+B The intensity information of the three color components, S, is calculated by signal calculation using R , S G , S B can be sought.

[0095] As described above, the configuration of the present embodiment 3 can achieve the same functions as those of the embodiment 1. The present embodiment 3 is similar to the embodiment 1 except for the differences from the above embodiment 1, and the common components have the same effects as those described in the embodiment 1, and can be modified in the same manner. Note that in a modified example in which a color filter is used in combination, it is desirable to place a color filter of a corresponding color component only on the pixel 102 directly below the microspectroscopic element 101.

[0096] (Embodiment 4) Next, an image sensor according to a fourth embodiment of the present invention will be described.

[0097] Fig. 15(a) is a top view of a schematic configuration of a part of an image sensor according to the fourth embodiment of the present invention, and Fig. 15(b) is a cross-sectional view thereof. As shown in Figs. 15(a) and (b), an image sensor 500 according to the fourth embodiment and an image sensor using the same are different from those of the second embodiment in that microlenses 103 are arranged in one-to-one correspondence with each pixel 102. Also, a matrix calculation using photoelectric conversion signals from each pixel 102 is used to obtain color information. The other components are the same as those of the second embodiment. The following description will focus on the differences from the second embodiment, and a description of the overlapping points will be omitted.

[0098] 15(b), the microlenses 103 are arranged in one-to-one correspondence with the pixels 102. Accordingly, of the white light incident on the image sensor 500, the light that is incident on each micro-spectroscopic element 101 and color-separated is only the light focused by the micro-spectroscopic element 103 located directly above the micro-spectroscopic element 101, and the other light passes through each micro-lens 103 and directly enters the pixel 102 directly below each micro-lens 103.

[0099] Here, as in the description of the third embodiment, if the intensity of the white light incident on a single microlens 103 is represented by W and the intensities of the three RGB colors that make up the white light are R, G, and B, respectively, then the white light is incident on the pixel 102D via the five microlenses 103. R , D G , D B The light incident on each pixel 102D has an intensity represented by W+2R, G, and W+2B. The above is just an example, and depending on the configuration of each micro-spectroscopic element 101, the combination of color components and propagation directions can be freely changed. R , D G , D B The composition of the color components incident on each of the pixels 102D is also changed. R , D G , D BWe will describe how color information is obtained by matrix calculation when light of intensities W+2R, G, and W+2B is incident on the microspectroscopic element 101, but it goes without saying that the numerical values ​​of the matrix operator can be changed depending on the configuration and spectroscopic performance of the microspectroscopic element 101.

[0100] The light having intensities of W+2R, G, and W+2B incident on each pixel 102 is photoelectrically converted by a photoelectric conversion element and output as a photoelectric conversion signal. Here, as in the description of the third embodiment, the photoelectric conversion signals corresponding to the light intensities of the three colors RGB and the white light W are represented as S R , S G , S B , S W The photoelectric conversion signals output by the pixels 102 on which light of intensities W+2R, G, and W+2B is incident are respectively represented as S W+2R , S G , S W+2B In addition, S W is S W =S R +S G +S B It is represented by S W+2R , S W+2B are respectively, S W+2R =S W +2S R , S W+2B =S W +2S B In addition, the pixel 102D G Since the light incident on the target is a G component split by the micro spectroscopic element 101, the light is G is output as is.

[0101] From the above, S R , S G , S B is the following S W+2R , S G , S W+2B It can be obtained by matrix calculation using

[0102]

number

[0103] Therefore, for each pixel D R , D G , D B Three photoelectric conversion signals S W+2R , S G , S W+2B The intensity information of the three color components, S, is calculated by signal calculation using R , S G , S B can be sought.

[0104] As described above, the configuration of the present embodiment 4 can achieve the same functions as those of the embodiment 2. The present embodiment 4 is similar to the embodiment 2 except for the differences from the embodiment 2, and the common components have the same effects as those described in the embodiment 2, and can be modified in the same manner. In a modified example in which a color filter is used in combination, it is desirable to place a color filter of the corresponding color component only on the pixel directly below the microspectroscopic element 101.

[0105] The above-mentioned first to fourth embodiments are merely preferred specific examples of the present invention, and the present invention is not limited to these, and various modifications are possible.

[0106] In the above-mentioned first to fourth embodiments, examples assuming that the material of the micro-spectroscopic element 101 is SiN are shown, but the present invention is not limited thereto. For example, when the imaging element of the present invention is used in the visible light region in which the wavelength of light is in the range of 380 to 800 nm, materials such as SiN, SiC, TiO2, and GaN are suitable as materials for the micro-spectroscopic element because they have a high refractive index and little absorption loss. In addition, for near-infrared light in the wavelength range of 800 to 1000 nm, materials such as Si, SiC, SiN, TiO2, GaAs, and GaN are suitable as materials with low loss for this light. Furthermore, in the near-infrared region of long wavelength bodies (such as 1.3 μm and 1.55 μm, which are communication wavelengths), InP and the like can be used in addition to the above-mentioned materials. Furthermore, when forming a micro-spectroscopic element by pasting and coating, examples of materials include polyimides such as fluorinated polyimide, BCB (benzocyclobutene), photocurable resins, UV epoxy resins, acrylic resins such as PMMA, and polymers such as general resists.

[0107] Similarly, in the above-described first to fourth embodiments, an example was shown in which SiO2 was assumed as the material of the transparent layer 111, but the present invention is not limited to this. Any material, such as a general glass material, SiO2, or an air layer, may be used as long as it has a refractive index lower than that of the micro-spectroscopic element material and has low loss with respect to the wavelength of the incident light.

[0108] In the above-described first to fourth embodiments, the three wavelength ranges that the micro-spectroscopic element 101 corresponds to are described as being light of the three primary colors of red, green, and blue. However, at least one of the three wavelength ranges may be light of a wavelength other than the three primary colors (for example, infrared light or ultraviolet light).

[0109] While the present invention has been described above based on specific embodiments, it goes without saying that the present invention is not limited to the above embodiments and can be modified in various ways without departing from the spirit of the present invention. [Explanation of symbols]

[0110] 1 object 10. Imaging device 11 Lens optical system 12 Image sensor 13 Signal Processing Section 100, 200, 300, 400, 500, 600, 610, 620 Image sensor 101 Microspectroscopic element 102 pixels 103 Micro Lens 104 Color Filters 111 Transparent layer 112 Wiring layer 121 Columnar structure 601 Wiring layer 602 pixels 603 Transparent layer 604 Color Filter 605 Micro Lens 606, 607 Microstructure

Claims

1. a pixel array in which a plurality of pixels, each including a photoelectric conversion element, are arranged on a substrate; a transparent layer formed on the pixel array; a spectroscopic element array in which a plurality of spectroscopic elements are arranged inside or on the transparent layer, An imaging element characterized in that each of the dispersive elements includes a set of microstructures consisting of a plurality of microstructures arranged in a direction perpendicular to the optical axis direction, disperses light in an asymmetric direction according to the wavelength, and a set of pixels consisting of a plurality of pixels of the pixel array corresponds to the set of microstructures.

2. The imaging element according to claim 1 , wherein the plurality of microscopic structures included in the set of microscopic structures do not all have the same shape.

3. 2 . The image sensor according to claim 1 , wherein the set of microscopic structures constituting the dispersing elements in the plurality of dispersing elements do not all have the same shape among the plurality of dispersing elements.

4. a pixel array in which a plurality of pixels, each including a photoelectric conversion element, are arranged on a substrate; a transparent layer formed on the pixel array; a spectroscopic element array in which a plurality of spectroscopic elements are arranged inside or on the transparent layer, Each of the dispersive elements includes a set of microstructures consisting of a plurality of microstructures arranged in a direction perpendicular to the optical axis direction, and disperses light in an asymmetric direction according to the wavelength, and at least a portion of the light incident on the set of microstructures included in each of the dispersive elements is separated into first to third polarized light beams having asymmetric propagation directions according to the wavelength, which exit from each of the dispersive elements and are incident on three of the pixels corresponding to the set of microstructures.

5. The imaging device according to claim 1 , an imaging optical system for forming an optical image on an imaging surface of the imaging element; a signal processing unit that processes an electrical signal output by the imaging element; An imaging device comprising:

Images