Optical element, manufacturing method, and electronic device

Abstract

[Problem] To provided better optical characteristics. [Solution] An optical element having a multistage structure in which a second meta-surface layer including, in a second film, a second nanopillar structure having a structure in which a plurality of second microstructures is planarly arranged is directly stacked on a first meta-surface layer including, in a first film, a first nanopillar structure having a structure in which a plurality of first microstructures is planarly arranged. The present technology can be applied to, for example, an image sensor including a meta-surface element.

Description

OPTICAL ELEMENT, MANUFACTURING METHOD, AND ELECTRONIC DEVICE

[0001] The present disclosure relates to an optical element, a manufacturing method, and an electronic device, and more particularly, to an optical element, a manufacturing method, and an electronic device capable of providing better optical characteristics. <CROSS REFERENCE TO RELATED APPLICATIONS>

[0002] This application claims the benefit of Japanese Priority Patent Application JP 2023-143333 filed September 5, 2023, the entire contents of which are incorporated herein by reference.

[0003] In the past, for example, development of a meta-surface, which is an optical element capable of controlling optical characteristics of a substance by planarly arranging microstructures in which microstructures having a size equal to or less than a wavelength of light are periodically arranged, has been advanced.

[0004] For example, Patent Literature 1 discloses an image sensor including a color separation lens array (multistage pillar type meta-surface element) having a configuration in which an etching prevention layer is provided between a first lens layer and a second lens layer in which nanoposts are arranged.

[0005] JP 2022-074062 A

[0006] However, in the multistage pillar type meta-surface element as disclosed in Patent Literature 1 described above, since the etching prevention layer serves as a reflection interface, there is a concern that optical characteristics such as quantum efficiency Qe may deteriorate.

[0007] The present disclosure is achieved in view of such a situation, and is directed to provide a better optical characteristic.

[0008] An optical element according to an aspect of the present disclosure includes: a first meta-surface layer that includes, in a first film, a first nanopillar structure having a structure in which a plurality of first microstructures is planarly arranged; and a second meta-surface layer that includes, in a second film, a second nanopillar structure having a structure in which a plurality of second microstructures is planarly arranged, the optical element having a multistage structure in which the second meta-surface layer is directly stacked on the first meta-surface layer.

[0009] A manufacturing method according to an aspect of the present disclosure is a manufacturing method of an optical element having a multistage structure in which a second meta-surface layer including, in a second film, a second nanopillar structure having a structure in which a plurality of second microstructures is planarly arranged is directly stacked on a first meta-surface layer including, in a first film, a first nanopillar structure having a structure in which a plurality of first microstructures is planarly arranged, the manufacturing method including: forming the second nanopillar structure by performing dry etching on an inorganic layer formed by depositing an inorganic material having a high refractive index on the entire surface of the first meta-surface layer, or forming the second nanopillar structure by filling an inorganic material having a high refractive index in an opening provided in a hard mask layer formed so as to be stacked on the first meta-surface layer.

[0010] An electronic device according to an aspect of the present disclosure includes an optical element including: a first meta-surface layer that includes, in a first film, a first nanopillar structure having a structure in which a plurality of first microstructures is planarly arranged; and a second meta-surface layer that includes, in a second film, a second nanopillar structure having a structure in which a plurality of second microstructures is planarly arranged, the optical element having a multistage structure in which the second meta-surface layer is directly stacked on the first meta-surface layer.

[0011] In an aspect of the present disclosure, a multistage structure is used in which a second meta-surface layer including, in a second film, a second nanopillar structure having a structure in which a plurality of second microstructures is planarly arranged is directly stacked on a first meta-surface layer including, in a first film, a first nanopillar structure having a structure in which a plurality of first microstructures is planarly arranged.

[0012] Figs. 1A to 1C are diagrams illustrating a configuration example of a first embodiment of a meta-surface element to which the present technology is applied.Fig. 2 is a diagram for explaining a manufacturing process of the meta-surface element in Figs. 1A to 1C.Fig. 3 is a diagram for explaining a manufacturing process of the meta-surface element in Figs. 1A to 1C.Figs. 4A to 4C are diagrams illustrating a configuration example of a second embodiment of the meta-surface element to which the present technology is applied.Fig. 5 is a diagram for explaining a manufacturing process of the meta-surface element in Figs. 4A to 4C.Fig. 6 is a diagram for explaining a manufacturing process of the meta-surface element in Figs. 4A to 4C.Fig. 7 is a diagram for explaining a manufacturing process of the meta-surface element in Figs. 4A to 4C.Fig. 8 is a diagram illustrating a configuration example of a third embodiment of the meta-surface element to which the present technology is applied.Fig. 9 is a diagram illustrating a configuration example of an image sensor to which the meta-surface element is applied.Fig. 10 is a block diagram illustrating a configuration example of an imaging device.Fig. 11 is a diagram illustrating a use example in which an image sensor is used.

[0013] Hereinafter, specific embodiments to which the present technology is applied will be described in detail with reference to the drawings.

[0014] <First configuration example of meta-surface element> A first embodiment of a meta-surface element to which the present technology is applied will be described with reference to Figs. 1A to 3.

[0015] Fig. 1A illustrates a cross-sectional configuration example of the meta-surface element, Fig. 1B illustrates a planar configuration example of a second meta-surface layer, and Fig. 1C illustrates a planar configuration example of a first meta-surface layer.

[0016] As illustrated in Fig. 1A, the meta-surface element 11 has a multistage structure (in the example illustrated in Fig. 1A, a two-stage structure) in which an etching prevention layer 21, a first meta-surface layer 22, and a second meta-surface layer 23 are stacked.

[0017] The etching prevention layer 21 is a layer serving as a stopper for etching performed when the first meta-surface layer 22 is formed, and can include, for example, a nitride film (SiN, SiON), hafnium oxide (HfO), aluminum oxide (AlO), or the like, and may have a stacked structure thereof. In addition, the film thickness of the etching prevention layer 21 is not particularly limited, and is preferably, for example, 1 nm to 1000 nm.

[0018] The first meta-surface layer 22 is stacked on the etching prevention layer 21, and includes a first nanopillar structure 32 having a structure in which a plurality of fine cylinders is planarly arranged inside a first film 31. For example, the first meta-surface layer 22 can have desired optical characteristics by appropriately designing the shape, pitch, diameter d1, and the like of individual fine cylinders forming the first nanopillar structure 32.

[0019] The second meta-surface layer 23 is stacked directly on the first meta-surface layer 22 (without interposing an etching prevention layer or the like), and a second nanopillar structure 42 having a structure in which a plurality of fine cylinders is planarly arranged inside the second film 41. For example, the second meta-surface layer 23 can have desired optical characteristics by appropriately designing the shape, pitch, diameter d2, and the like of individual fine cylinders forming the second nanopillar structure 42.

[0020] In addition, the film thickness of each of the first meta-surface layer 22 and the second meta-surface layer 23 is not particularly limited, and is preferably, for example, 10 nm to 2000 nm. In addition, the first meta-surface layer 22 and the second meta-surface layer 23 may be formed so that the film thickness of either one is thick, or the film thicknesses of both may be equal.

[0021] For example, in a case where an inorganic material having a low refractive index is used, the first film 31 and the second film 41 may include an oxide film (SiO) or air, and in a case where an organic material having a low refractive index is used, the first film 31 and the second film 41 may include a resin, and may include a combination thereof. In addition, it is possible to use an inorganic material or an organic material having a low refractive index of different materials for the first film 31 and the second film 41, and a material having a low refractive index is used for the second film 41 rather than the first film 31.

[0022] The first nanopillar structure 32 and the second nanopillar structure 42 include an inorganic material having a high refractive index, and may include, for example, an oxide film (TiO), a nitride film (SiN, SiON), single crystal silicon (c-Si), polycrystalline silicon (p-Si), amorphous silicon (a-Si), gallium phosphide (GaP), gallium nitride (GaN), gallium arsenide (GaAs), silicon carbide (SiC), and the like, and may include a combination thereof. In addition, the first nanopillar structure 32 and the second nanopillar structure 42 may include air as long as the effective refractive index is higher than that of the first film 31 and the second film 41.

[0023] In addition, the diameter d1 of each fine cylinder of the first nanopillar structure 32 and the diameter d2 of each fine cylinder of the second nanopillar structure 42 are not particularly limited, and are preferably formed to be, for example, 80 nm to 800 nm. In addition, high refractive index inorganic materials of different materials can be used for the first nanopillar structure 32 and the second nanopillar structure 42. Note that the shape of the microstructures constituting the first nanopillar structure 32 and the second nanopillar structure 42 is not limited to a cylindrical shape as long as it is formed in a columnar shape.

[0024] The meta-surface element 11 configured in this manner has a configuration in which the second meta-surface layer 23 is directly stacked on the first meta-surface layer 22, and thus, for example, it is possible to have better optical characteristics as compared with a configuration in which an etching prevention layer or the like is provided therebetween. For example, the meta-surface element 11 can reduce the reflection interface as compared with the multistage pillar type meta-surface element disclosed in Patent Literature 1 described above, and as a result, deterioration of optical characteristics such as the quantum efficiency Qe can be avoided.

[0025] Furthermore, in the meta-surface element 11, by using an inorganic material having a lower refractive index for the second film 41, reflection to external light incident on the second meta-surface layer 23 can be suppressed, and it is expected to improve flare, the quantum efficiency Qe, and the like. As a result, in the meta-surface element 11, for example, it is not necessary to provide an antireflection film, and as a result, it is possible to avoid occurrence of film peeling that is concerned in a configuration in which the antireflection film is provided. In addition, in the meta-surface element 11, by adopting a configuration using a resin as the second film 41, impact relaxation at the time of chip transfer can be expected by the second film 41 serving as a buffer, and for example, chip breakage can be suppressed to further improve quality.

[0026] A manufacturing process of the meta-surface element 11 will be described with reference to Figs. 2 and 3.

[0027] In a first step, as illustrated in the first stage of Fig. 2, the first meta-surface layer 22 is formed so as to be stacked on the etching prevention layer 21. For example, in the first film 31 formed on the entire surface of the etching prevention layer 21, the first meta-surface layer 22 is formed by providing a plurality of openings by performing dry etching on a portion where the first nanopillar structure 32 is provided, and filling an inorganic material having a high refractive index in the openings to form the first nanopillar structure 32. The first meta-surface layer 22 is preferably configured using, for example, TEOS (n = 1.47) as the first film 31 and using TiO (n = 2.47) as the first nanopillar structure 32.

[0028] In a second step, as illustrated in the second stage of Fig. 2, an inorganic material having a high refractive index is formed on the entire surface of the first meta-surface layer 22, and an inorganic layer 51 is formed so as to be directly stacked on the first meta-surface layer 22. For example, it is preferable to use SiN (n = 1.88) for the inorganic layer 51.

[0029] In a third step, as illustrated in the third stage of Fig. 2, a resist film 52 provided corresponding to a portion where the second nanopillar structure 42 is provided is formed so as to be stacked on the inorganic layer 51.

[0030] In a fourth step, as illustrated in the first stage of Fig. 3, the second nanopillar structure 42 is formed by performing dry etching on the inorganic layer 51 using the resist film 52 as a mask. Here, at the time of processing the inorganic layer 51, it is necessary to set an appropriate selection ratio so that the first film 31 and the first nanopillar structure 32 of the first meta-surface layer 22 can be used as stopper films.

[0031] In a fourth step, as illustrated in the second stage of Fig. 3, the second film 41 is formed so as to fill the second nanopillar structure 42 to form the second meta-surface layer 23. For example, it is preferable to use a resin (n = 1.41) for the second film 41. Thus, the meta-surface element 11 can be manufactured.

[0032] By the manufacturing process as described above, the meta-surface element 11 having better optical characteristics can be manufactured with the configuration in which the second meta-surface layer 23 is directly stacked on the first meta-surface layer 22.

[0033] In addition, in the meta-surface element 11, the second nanopillar structure 42 is formed by performing dry etching on the inorganic layer 51 using the resist film 52 as a mask, so that the tip surface of the second nanopillar structure 42 can be formed flat. As a result, for example, formation of a seam, a recess, and the like on the tip surface of the second nanopillar structure 42 is avoided, and diffuse reflection due to the seam, the recess, and the like can be eliminated. As a result, it is expected to further improve optical characteristics.

[0034] <Second configuration example of meta-surface element> A second embodiment of the meta-surface element to which the present technology is applied will be described with reference to Figs. 4A to 7.

[0035] Fig. 4A illustrates a cross-sectional configuration example of the meta-surface element, Fig. 4B illustrates a planar configuration example of a second meta-surface layer, and Fig. 4C illustrates a planar configuration example of the first meta-surface layer. Note that, in a meta-surface element 11A illustrated in Figs. 4A to 4C, the same reference numerals are given to the same configurations as those of the meta-surface element 11 in Figs. 1A to 1C, and a detailed description thereof will be omitted.

[0036] As illustrated in Fig. 4A, the meta-surface element 11A has a multistage structure (in the example illustrated in Fig. 4A, a two-stage structure) in which the etching prevention layer 21, the first meta-surface layer 22, and a second meta-surface layer 23A are stacked. The etching prevention layer 21 and the first meta-surface layer 22 are configured similarly to the meta-surface element 11 in Fig. 1A to 1C.

[0037] The second meta-surface layer 23A is stacked directly on the first meta-surface layer 22 (without interposing an etching prevention layer or the like), and a second nanopillar structure 42A having a structure in which a plurality of fine cylinders is planarly arranged inside the second film 41. The second meta-surface layer 23A includes an inorganic material having a high refractive index similarly to the second meta-surface layer 23 in Figs. 1A and 1B, and is formed by a manufacturing process different from that of the second meta-surface layer 23 in Figs. 1A and 1B.

[0038] The meta-surface element 11A configured in this manner can have better optical characteristics, similarly to the meta-surface element 11 in Fig. 1A.

[0039] A manufacturing process of the meta-surface element 11A will be described with reference to Figs. 5 to 7.

[0040] In an eleventh step, as illustrated in the first stage of Fig. 5, the first meta-surface layer 22 is formed so as to be stacked on the etching prevention layer 21. The first meta-surface layer 22 is preferably configured using, for example, TEOS (n = 1.47) as the first film 31 and using TiO (n = 2.47) as the first nanopillar structure 32.

[0041] In a twelfth step, as illustrated in the second stage of Fig. 5, for example, amorphous silicon (a-Si) is deposited so as to be stacked on the entire surface of the first meta-surface layer 22, thereby forming a hard mask layer 61.

[0042] In a thirteenth step, as illustrated in the third stage of Fig. 5, a resist film 62 is formed so as to be stacked on the hard mask layer 61 such that a portion where the second nanopillar structure 42A is provided is opened.

[0043] In a fourteenth step, as illustrated in the first stage of Fig. 6, dry etching is performed on the hard mask layer 61 using the resist film 62 as a mask to form openings in the hard mask layer 61.

[0044] In a fifteenth step, as illustrated in the second stage of Fig. 6, an inorganic material 63 having a high refractive index is filled in the openings provided in the hard mask layer 61. For example, TiO (n = 2.47) is preferably used for the inorganic material 63 having a high refractive index.

[0045] In a sixteenth step, as illustrated in the third stage of Fig. 6, the inorganic material 63 having a high refractive index formed on the surface of the hard mask layer 61 is removed by, for example, chemical mechanical polishing (CMP) to form the second nanopillar structure 42A.

[0046] In a seventeenth step, as illustrated in the first stage of Fig. 7, the hard mask layer 61 is peeled off using, for example, a chemical liquid (AKW, TMAH).

[0047] In an eighteenth step, as illustrated in the second stage of Fig. 7, the second film 41 is formed so as to fill the second nanopillar structure 42 to form the second meta-surface layer 23A. For example, it is preferable to use a resin (n = 1.41) for the second film 41. Thus, the meta-surface element 11A can be manufactured.

[0048] By the manufacturing process as described above, the meta-surface element 11A having better optical characteristics can be manufactured with the configuration in which the second meta-surface layer 23A is directly stacked on the first meta-surface layer 22.

[0049] <Third configuration example of meta-surface element> A third embodiment of the meta-surface element to which the present technology is applied will be described with reference to Fig. 8.

[0050] Fig. 8 illustrates a cross-sectional configuration example of the meta-surface element. Note that, in a meta-surface element 11B illustrated in Fig. 8, the same reference numerals are given to the same configurations as those of the meta-surface element 11 in Figs. 1A to 1C, and a detailed description thereof will be omitted.

[0051] As illustrated in Fig. 8, the meta-surface element 11B has a multistage structure (in the example illustrated in Fig. 8, a two-stage structure) in which the etching prevention layer 21, the first meta-surface layer 22, and a second meta-surface layer 23B are stacked. The etching prevention layer 21 and the first meta-surface layer 22 are configured similarly to the meta-surface element 11 in Fig. 1A to 1C.

[0052] The second meta-surface layer 23B has a configuration different from that of the second meta-surface layer 23 in Figs. 1A and 1B in that a protective film 71 for protecting the second nanopillar structure 42 is provided. The protective film 71 can be formed by forming an oxide film (SiO) on the second nanopillar structure 42 by, for example, an atomic layer deposition (ALD) method after the formation of the second nanopillar structure 42 and before the formation of the second film 41.

[0053] The meta-surface element 11B configured in this manner can prevent, for example, the collapse of the fine cylinders of the second nanopillar structure 42 by the configuration of protecting the second nanopillar structure 42 with the protective film 71, and can further improve the quality.

[0054] <Application example to image sensor> An application example of the meta-surface element to an image sensor will be described with reference to Fig. 9.

[0055] An image sensor 81 includes a plurality of pixels 82 arranged in an array, and the meta-surface element 11 arranged on a light incident surface side of the pixels 82. Fig. 9 illustrates a cross-sectional configuration example of a red pixel 82R, a green pixel 82G, and a blue pixel 82B.

[0056] The image sensor 81 is configured by stacking a semiconductor substrate 85 in which a photodiode PD is provided for each of the pixels 82, a filter layer 86 in which color filters that transmit light received by respective pixels 82 are provided, and a planarizing film 87 that planarizes a surface, and the meta-surface element 11 is stacked on the planarizing film 87.

[0057] For example, the meta-surface element 11 can be configured such that the first meta-surface layer 22 and the second meta-surface layer 23 have a function as microlenses that condense light for each pixel 82. Furthermore, the first meta-surface layer 22 and the second meta-surface layer 23 may be configured to have various functions according to the application of the image sensor 81, such as condensing only light in a specific wavelength region.

[0058] Furthermore, the meta-surface element 11 may have a configuration in which a first sidewall protective film 83 is provided on the first meta-surface layer 22 and a second sidewall protective film 84 is provided on the second meta-surface layer 23 at a position between the pixels 82. The first sidewall protective film 83 includes an inorganic material having a high refractive index common to the first nanopillar structure 32, and can be collectively formed with the first nanopillar structure 32. The second sidewall protective film 84 includes an inorganic material having a high refractive index common to the second nanopillar structure 42, and can be collectively formed with the second nanopillar structure 42. Note that a part of the first sidewall protective film 83 and a part of the second sidewall protective film 84 may include a material having a light blocking property such as black resist or tungsten as a countermeasure against flare.

[0059] Furthermore, the meta-surface element 11 is not limited to the configuration provided for the image sensor 81 as illustrated, and may be provided on another type of sensor, a glass substrate, and the like.

[0060] Note that, in the present embodiment, the meta-surface element 11 having a two-stage structure in which the first meta-surface layer 22 and the second meta-surface layer 23 are stacked has been described, but the meta-surface element 11 may have a multistage structure of three or more stages. Although not illustrated, in the meta-surface element 11 of each of the above-described embodiments, an antireflection film may be stacked on the second meta-surface layer 23. An oxide film similar to the second film 41 can be used as the antireflection film, and a single layer or a plurality of layers may be combined, and the antireflection film is preferably formed with a film thickness of 10 nm to 3000 nm.

[0061] <Configuration example of electronic device> The above-described image sensor 81 may be applied to various electronic devices such as an imaging system such as a digital still camera and a digital video camera, a mobile phone having an imaging function, or another device having an imaging function, for example.

[0062] Fig. 10 is a block diagram illustrating a configuration example of an imaging device mounted on an electronic device.

[0063] As illustrated in Fig. 10, an imaging device 101 includes an optical system 102, an imaging element 103, a signal processing circuit 104, a monitor 105, and a memory 106, and can capture a still image and a moving image.

[0064] The optical system 102 includes one or a plurality of lenses, guides image light (incident light) from a subject to the imaging element 103, and forms an image on a light receiving surface (sensor unit) of the imaging element 103.

[0065] As the imaging element 103, the image sensor 81 described above is used. Electrons are accumulated in the imaging element 103 for a certain period in accordance with the image formed on the light receiving surface via the optical system 102. Then, a signal corresponding to the electrons accumulated in the imaging element 103 is supplied to the signal processing circuit 104.

[0066] The signal processing circuit 104 performs various types of signal processing on the pixel signal output from the imaging element 103. An image (image data) obtained by performing signal processing by the signal processing circuit 104 is supplied to and displayed on the monitor 105, or supplied to and stored (recorded) in the memory 106.

[0067] The imaging device 101 configured as described above can capture, for example, a higher quality image by using the above-described image sensor 81.

[0068] <Use example of image sensor> Fig. 11 is a view illustrating a usage example to use the above-described image sensor.

[0069] The image sensor can be used in various cases for sensing light such as visible light, infrared light, ultraviolet light, and X-ray as described below, for example.

[0070] - A device that captures an image to be used for viewing, such as a digital camera and a portable device with a camera function - A device for traffic purpose such as an in-vehicle sensor that takes images of the front, rear, surroundings, interior and the like of an automobile, a monitoring camera that monitors traveling vehicles and roads, and a distance measuring sensor that measures a distance between vehicles and the like for safe driving such as automatic stop, recognition of a driver’s condition and the like - A device for home appliance such as a television, a refrigerator, and an air conditioner that images a user’s gesture and performs device operation according to the gesture - A device for medical and health care use such as an endoscope and a device that performs angiography by receiving infrared light - A device for security use such as a security monitoring camera and an individual authentication camera - A device used for beauty care, such as a skin measuring instrument for imaging skin, and a microscope for imaging the scalp - A device used for sport, such as an action camera or a wearable camera for sports applications or the like - A device used for agriculture, such as a camera for monitoring a condition of a field or crop

[0071] <Combination examples of configurations> Note that the present technology can also have the following configuration. (1) An optical element including: a first meta-surface layer that includes, in a first film, a first nanopillar structure having a structure in which a plurality of first microstructures is planarly arranged; and a second meta-surface layer that includes, in a second film, a second nanopillar structure having a structure in which a plurality of second microstructures is planarly arranged, the optical element having a multistage structure in which the second meta-surface layer is directly stacked on the first meta-surface layer. (2) The optical element according to (1) described above, in which the first film and the second film include an inorganic material or an organic material having a low refractive index, and the first nanopillar structure and the second nanopillar structure include an inorganic material having a high refractive index. (3) The optical element according to (2) described above, in which the first nanopillar structure and the second nanopillar structure include an oxide film or a nitride film. (4) The optical element according to any one of (1) to (3) described above, in which the first film and the second film are different in material, and the first nanopillar structure and the second nanopillar structure are different in material. (5) The optical element according to any one of (1) to (4) described above, in which a material having a lower refractive index is used for the second film than the first film. (6) The optical element according to any one of (1) to (5) described above, in which the second film includes a resin. (7) The optical element according to (6) described above, in which a protective film is formed on the second nanopillar structure in the second meta-surface layer. (8) The optical element according to any one of (1) to (7) described above, further including an etching prevention layer on which the first meta-surface layer is stacked. (9) The optical element according to any one of (1) to (8) described above, further including an antireflection film stacked on the second meta-surface layer. (10) A manufacturing method of an optical element having a multistage structure in which a second meta-surface layer including, in a second film, a second nanopillar structure having a structure in which a plurality of second microstructures is planarly arranged is directly stacked on a first meta-surface layer including, in a first film, a first nanopillar structure having a structure in which a plurality of first microstructures is planarly arranged, the manufacturing method including: forming the second nanopillar structure by performing dry etching on an inorganic layer formed by depositing an inorganic material having a high refractive index on the entire surface of the first meta-surface layer. (11) A manufacturing method of an optical element having a multistage structure in which a second meta-surface layer including, in a second film, a second nanopillar structure having a structure in which a plurality of second microstructures is planarly arranged is directly stacked on a first meta-surface layer including, in a first film, a first nanopillar structure having a structure in which a plurality of first microstructures is planarly arranged, the manufacturing method including: forming the second nanopillar structure by filling an inorganic material having a high refractive index in an opening provided in a hard mask layer formed so as to be stacked on the first meta-surface layer. (12) An electronic device including an optical element, the optical element including: a first meta-surface layer that includes, in a first film, a first nanopillar structure having a structure in which a plurality of first microstructures is planarly arranged; and a second meta-surface layer that includes, in a second film, a second nanopillar structure having a structure in which a plurality of second microstructures is planarly arranged, the optical element having a multistage structure in which the second meta-surface layer is directly stacked on the first meta-surface layer.

[0072] Note that the present technology can also have the following configuration. (1) An optical element comprising: a first meta-surface layer that includes, in a first film, a first pillar structure having a plurality of first structures; and a second meta-surface layer that includes, in a second film, a second pillar structure having a plurality of second structures, wherein the second meta-surface layer is in contact with the first meta-surface layer. (2) The optical element according to (1), wherein at least one of the first film or the second film includes a material a refractive index lower than at least one of a refractive index of the first pillar structure or a refractive index of the second pillar structure. (3) The optical element according to (1) or (2), wherein the first film and the second film include an inorganic material or an organic material. (4) The optical element according to any one of (1) to (3), wherein the inorganic material includes, an oxide film (TiO), a nitride film (SiN, SiON), single crystal silicon (c-Si), polycrystalline silicon (p-Si), amorphous silicon (a-Si), gallium phosphide (GaP), gallium nitride (GaN), gallium arsenide (GaAs), silicon carbide (SiC), or a combination thereof. (5) The optical element according to any one of (1) to (4), wherein at least one of the first pillar structure or the second pillar structure includes a material having a refractive index higher than at least one of a refractive index of the first film or a refractive index of the second film. (6) The optical element according to any one of (1) to (5), wherein the first pillar structure and the second pillar structure include an oxide film or a nitride film. (7) The optical element according to any one of (1) to (6), wherein the first film and the second film are different in material. (8) The optical element according to any one of (1) to (7), wherein the first pillar structure and the second pillar structure are different in material. (9) The optical element according to any one of (1) to (8), wherein a material having a lower refractive index is used for the second film than the first film. (10) The optical element according to any one of (1) to (9), wherein the second film includes a resin. (11) The optical element according to any one of (1) to (10), wherein a protective film is formed on the second meta-surface layer. (12) The optical element according to any one of (1) to (11), further comprising an etching prevention layer, wherein the etching prevention layer is in contact with a first surface of the first meta-surface layer, and wherein a second surface of the first meta-surface layer is in contact with a first surface of the second meta-surface layer. (13) The optical element according to any one of (1) to (12), further comprising an antireflection film is in contact with a second surface of the second meta-surface layer. (14) The optical element according to any one of (1) to (13), wherein the optical element has a multistage structure. (15) The optical element according to any one of (1) to (14), wherein at least one of the first pillar structure or the second pillar structure includes a nanopillar structure. (16) The optical element according to any one of (1) to (15), wherein at least one of the first pillar structure or the second pillar structure includes an inorganic material. (17) A manufacturing method of an optical element in which a second meta-surface layer including, in a second film, a second pillar structure having a plurality of second structures is in contact with a first surface of a first meta-surface layer including, in a first film, a first pillar structure having a plurality of first structures, the manufacturing method comprising: forming the second pillar structure by performing dry etching on an inorganic layer formed by depositing an inorganic material having a high refractive index on an entire first surface of the first meta-surface layer. (18) A manufacturing method of an optical element in which a second meta-surface layer including, in a second film, a second pillar structure having a plurality of second structures is in contact with a first surface of a first meta-surface layer including, in a first film, a first pillar structure having a plurality of first structures, the manufacturing method comprising: forming the second pillar structure by filling an inorganic material having a high refractive index in an opening provided in a hard mask layer formed so as to be in contact with the first surface of the first meta-surface layer. (19) An electronic device comprising an optical element and a circuit, the optical element including: a first meta-surface layer that includes, in a first film, a first pillar structure having a plurality of first structures; and a second meta-surface layer that includes, in a second film, a second pillar structure having a plurality of second structures, the optical element having a multistage structure in which the second meta-surface layer is in contact with a first surface of the first meta-surface layer. (20) A photodetector comprising: a photoelectric conversion element; a first meta-surface layer that includes, in a first film, a first pillar structure having a plurality of first structures; and a second meta-surface layer that includes, in a second film, a second pillar structure having a plurality of second structures, wherein the second meta-surface layer is in contact with the first meta-surface layer.

[0073] Note that, the present embodiment is not limited to the embodiments described above, and various alterations can be made without departing from the gist of the present disclosure. Furthermore, effects described in the present description are merely examples and are not limited, and other effects may also be provided.

[0074] 11 Meta-surface element 21 Etching prevention layer 22 First meta-surface layer 23 Second meta-surface layer 31 First film 32 First nanopillar structure 41 Second film 42 Second nanopillar structure 51 Inorganic layer 52 Resist film 61 Hard mask layer 62 Resist film 63 Inorganic material 71 Protective film 81 Image sensor 82 Pixel 83 First sidewall protective film 84 Second sidewall protective film 85 Semiconductor substrate 86 Filter layer 87 Planarizing film

Claims

1. An optical element comprising: a first meta-surface layer that includes, in a first film, a first pillar structure having a plurality of first structures; and a second meta-surface layer that includes, in a second film, a second pillar structure having a plurality of second structures, wherein the second meta-surface layer is in contact with the first meta-surface layer.

2. The optical element according to claim 1, wherein at least one of the first film or the second film includes a material a refractive index lower than at least one of a refractive index of the first pillar structure or a refractive index of the second pillar structure.

3. The optical element according to claim 1, wherein the first film and the second film include an inorganic material or an organic material.

4. The optical element according to claim 3, wherein the inorganic material includes, an oxide film (TiO), a nitride film (SiN, SiON), single crystal silicon (c-Si), polycrystalline silicon (p-Si), amorphous silicon (a-Si), gallium phosphide (GaP), gallium nitride (GaN), gallium arsenide (GaAs), silicon carbide (SiC), or a combination thereof.

5. The optical element according to claim 1, wherein at least one of the first pillar structure or the second pillar structure includes a material having a refractive index higher than at least one of a refractive index of the first film or a refractive index of the second film.

6. The optical element according to claim 1, wherein the first pillar structure and the second pillar structure include an oxide film or a nitride film.

7. The optical element according to claim 1, wherein the first film and the second film are different in material.

8. The optical element according to claim 1, wherein the first pillar structure and the second pillar structure are different in material.

9. The optical element according to claim 1, wherein a material having a lower refractive index is used for the second film than the first film.

10. The optical element according to claim 1, wherein the second film includes a resin.

11. The optical element according to claim 1, wherein a protective film is formed on the second meta-surface layer.

12. The optical element according to claim 1, further comprising an etching prevention layer, wherein the etching prevention layer is in contact with a first surface of the first meta-surface layer, and wherein a second surface of the first meta-surface layer is in contact with a first surface of the second meta-surface layer.

13. The optical element according to claim 1, further comprising an antireflection film is in contact with a second surface of the second meta-surface layer.

14. The optical element according to claim 1, wherein the optical element has a multistage structure.

15. The optical element according to claim 1, wherein at least one of the first pillar structure or the second pillar structure includes a nanopillar structure.

16. The optical element according to claim 1, wherein at least one of the first pillar structure or the second pillar structure includes an inorganic material.

17. A manufacturing method of an optical element in which a second meta-surface layer including, in a second film, a second pillar structure having a plurality of second structures is in contact with a first surface of a first meta-surface layer including, in a first film, a first pillar structure having a plurality of first structures, the manufacturing method comprising: forming the second pillar structure by performing dry etching on an inorganic layer formed by depositing an inorganic material having a high refractive index on an entire first surface of the first meta-surface layer.

18. A manufacturing method of an optical element in which a second meta-surface layer including, in a second film, a second pillar structure having a plurality of second structures is in contact with a first surface of a first meta-surface layer including, in a first film, a first pillar structure having a plurality of first structures, the manufacturing method comprising: forming the second pillar structure by filling an inorganic material having a high refractive index in an opening provided in a hard mask layer formed so as to be in contact with the first surface of the first meta-surface layer.

19. An electronic device comprising an optical element and a circuit, the optical element including: a first meta-surface layer that includes, in a first film, a first pillar structure having a plurality of first structures; and a second meta-surface layer that includes, in a second film, a second pillar structure having a plurality of second structures, wherein the second meta-surface layer is in contact with a first surface of the first meta-surface layer.

20. A photodetector comprising: a photoelectric conversion element; a first meta-surface layer that includes, in a first film, a first pillar structure having a plurality of first structures; and a second meta-surface layer that includes, in a second film, a second pillar structure having a plurality of second structures, wherein the second meta-surface layer is in contact with the first meta-surface layer.

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