JP2015225966A - Lens, manufacturing method of the same, imaging device, and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens capable of easily achieving a desired refractive index distribution while having a substantially flat surface shape and a manufacturing method of the same.SOLUTION: The lens has a refractive index distribution including a first refractive index on the periphery of an optical axis in a plane perpendicular to the optical axis and a second refractive index different from the first refractive index at least on part of the optical axis.

Description

  The present disclosure relates to, for example, a gradient index lens, a method for manufacturing the lens, and an imaging device and a display device using such a lens.

  A GRIN (gradient index lens) lens having a non-uniform refractive index (refractive index distribution type) is used as a lens used in an imaging device or a display device (Patent Documents 1 to 3). In the method of Patent Document 1, ions are implanted into a lens forming material layer, and the implanted ions are diffused to form a refractive index distribution in the material layer. On the other hand, in the method of Patent Document 2, a refractive index distribution is formed by aggregating a high refractive index material and a low refractive index material using a photosensitive material. Specifically, a mask is formed on a material layer in which a high refractive index material and a low refractive index material are mixed, and a selective region is exposed. Thereby, the high refractive index material is aggregated in the portion irradiated with light, and the low refractive index material excluded by the aggregation is distributed in the periphery, and a refractive index distribution is formed. As another technique using a photosensitive material, there is a technique disclosed in Patent Document 3. In the technique disclosed in Patent Document 3, a refractive index distribution is obtained by using a mask (gray mask) composed of fine dots or a gray pattern. Control is performed.

JP 2006-54413 A JP 59-204519 A JP 2005-210013 A

  However, in the method of Patent Document 1, since an inorganic layer having a sufficient thickness for obtaining a lens effect is formed by vapor deposition, a strong stress is applied after the film formation, and the substrate is likely to warp. Further, the refractive index distribution is limited to a hemispherical region centered on the mask opening, and the degree of freedom of distribution control is low. Also in the method of Patent Document 2, the refractive index distribution is limited to a hemispherical region centered on the mask opening. In Patent Document 3, a mask composed of fine dots or a gray pattern is used. However, since light is attenuated as it proceeds in the thickness direction of the lens layer, it is difficult to obtain a desired refractive index distribution. In addition, since a very fine processing technique is required to form a fine dot or gray mask, mask formation becomes difficult when the horizontal dimension of the lens is very small. On the other hand, when the horizontal dimension of the lens is large, the thickness of the lens increases to the same extent. For this reason, it is difficult to control the refractive index distribution using a photosensitive material. Moreover, the freedom degree of selection of the resin material is also low.

  The present disclosure has been made in view of such problems, and an object of the present disclosure is to provide a lens capable of easily realizing a desired refractive index distribution while having a substantially flat surface shape, and a method of manufacturing the lens. An object of the present invention is to provide an imaging device and a display device using such a lens.

  The lens according to the present disclosure includes, in a plane perpendicular to the optical axis, a first refractive index around the optical axis and a second refractive index that is different from the first refractive index in at least a part on the optical axis. It has a refractive index distribution.

  The method of manufacturing a lens according to the present disclosure includes a first refractive index in the periphery of the optical axis and a second refractive index different from the first refractive index in at least part of the optical axis in a plane perpendicular to the optical axis. Is formed.

  In the lens and the lens manufacturing method of the present disclosure, the first refractive index in the periphery of the optical axis and the first refraction in at least a part on the optical axis are within a plane perpendicular to the optical axis regardless of the surface shape. A refractive index profile is generated that includes a second refractive index different from the refractive index. Thereby, irrespective of the surface shape, for example, a lens function as a so-called convex lens or concave lens is exhibited.

  An imaging apparatus according to the present disclosure includes the lens according to the present disclosure.

  A display device according to the present disclosure includes the lens according to the present disclosure.

  According to the lens of the present disclosure and the manufacturing method of the lens, and the imaging device and the display device of the present disclosure, the first refractive index around the optical axis in a plane perpendicular to the optical axis, regardless of the surface shape, A refractive index distribution including a first refractive index and a second refractive index different from at least a part of the optical axis can be formed. Therefore, it is possible to easily realize a desired refractive index distribution while having a substantially flat surface shape.

  The above content is an example of the present disclosure. The effects of the present disclosure are not limited to those described above, and may be other different effects or may include other effects.

It is a cross-sectional schematic diagram showing the structure of the lens which concerns on 1st Embodiment of this indication. 1B is a schematic plan view of the lens shown in FIG. 1A. FIG. It is a cross-sectional schematic diagram for demonstrating the manufacturing method of the lens shown in FIG. It is a cross-sectional schematic diagram for demonstrating the process following FIG. 2A. It is a cross-sectional schematic diagram for demonstrating the process following FIG. 2B. It is a cross-sectional schematic diagram for demonstrating the process following FIG. 3A. It is a cross-sectional schematic diagram for demonstrating the process following FIG. 3B. It is a cross-sectional schematic diagram for demonstrating the process following FIG. 3C. FIG. 5 is a schematic cross-sectional view for explaining a process following the process in FIG. 4. It is a cross-sectional schematic diagram for demonstrating the process of following FIG. 5A. FIG. 5B is a schematic plan view corresponding to the cross-sectional configuration of FIG. 5A. FIG. 5B is a schematic plan view corresponding to the cross-sectional configuration of FIG. 5B. It is a schematic diagram for demonstrating the surface shape of the lens obtained by the process of FIG. 2A-FIG. 5D. It is a schematic diagram for demonstrating the surface shape of the lens obtained by the process of FIG. 2A-FIG. 5D. It is a schematic diagram for demonstrating the surface shape of the lens obtained by the process of FIG. 2A-FIG. 5D. 10 is a schematic cross-sectional view for explaining a method for manufacturing a lens according to Modification 1. FIG. It is a cross-sectional schematic diagram for demonstrating the process following FIG. 7A. It is a cross-sectional schematic diagram for demonstrating the process following FIG. 7B. It is a cross-sectional schematic diagram for demonstrating the manufacturing method of the lens which concerns on the modification 2-1. It is a cross-sectional schematic diagram for demonstrating the process of following FIG. 8A. It is a cross-sectional schematic diagram for demonstrating the process of following FIG. 8B. It is a cross-sectional schematic diagram for demonstrating the manufacturing method of the lens which concerns on the modification 2-2. It is a cross-sectional schematic diagram for demonstrating the process of following FIG. 8A. It is a cross-sectional schematic diagram for demonstrating the process of following FIG. 8B. It is a cross-sectional schematic diagram showing the structure of the lens which concerns on 2nd Embodiment of this indication. It is a cross-sectional schematic diagram for demonstrating the manufacturing method of the lens shown in FIG. It is a cross-sectional schematic diagram for demonstrating the process following FIG. 11A. It is a cross-sectional schematic diagram for demonstrating the process following FIG. 11B. It is a cross-sectional schematic diagram for demonstrating the process following FIG. It is a cross-sectional schematic diagram for demonstrating the process of following FIG. 13A. 10 is a schematic cross-sectional view for explaining a method for manufacturing a lens according to Modification 3. FIG. It is a cross-sectional schematic diagram for demonstrating the process following FIG. 14A. It is a cross-sectional schematic diagram for demonstrating the process following FIG. 14B. It is a cross-sectional schematic diagram for demonstrating the process following FIG. 14C. It is a cross-sectional schematic diagram for demonstrating the process following FIG. 14D. It is a cross-sectional schematic diagram for demonstrating the process following FIG. 10 is a schematic cross-sectional view for explaining a method for manufacturing a lens according to Modification 4. FIG. FIG. 18 is a schematic cross-sectional view for illustrating a process following the process in FIG. 17. It is a cross-sectional schematic diagram (left diagram) and a plan schematic diagram (right diagram) for describing a method for manufacturing a lens according to Modification 5. It is a cross-sectional schematic diagram (left figure) and a plane schematic diagram (right figure) for demonstrating the process following FIG. 10 is a schematic cross-sectional view for explaining a configuration of a lens according to Modification 6. FIG. It is a schematic diagram showing the whole structure of the imaging device or display apparatus which concerns on an application example.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The order of explanation is as follows.

1. First embodiment (an example of a lens that forms a refractive index distribution by diffusing a second resin layer embedded in a first resin layer)
2. Modification 1 (Another example of the recess forming method)
3. Modified examples 2-1 and 2-2 (other examples of resin embedding methods)
4). Second Embodiment (Example of a lens having a refractive index distribution in the in-plane direction and the thickness direction)
5. Modification 3 (example when the position and depth of the recess are changed according to the distance from the optical axis)
6). Modification 4 (example when the position and depth of the recess are changed according to the distance from the optical axis)
7). Modification 5 (example in the case of having a refractive index distribution only along one axial direction in the plane)
8). Modification 6 (example in which a lens layer is formed on an underlayer via an inorganic protective film)
9. Application example (example of imaging device and display device)

<First Embodiment>
[Constitution]
FIG. 1A schematically illustrates a cross-sectional configuration of a lens (lens 10) according to the first embodiment of the present disclosure. FIG. 1B schematically shows a planar configuration of the lens 10. 1A corresponds to a cross section taken along line IA-IA in FIG. 1B. Further, the refractive index distribution is schematically represented by shading, and is expressed so that the higher the refractive index, the darker (close to black), and the lower the refractive index, the lighter (close to white). In addition, the cross-sectional view shows a configuration cut along a plane passing through the optical axis (optical axis Z) of the lens 10 and parallel to the optical axis Z. The same applies to the following second embodiment and modifications.

  The lens 10 is disposed, for example, on a light receiving side of a pixel unit in an imaging device described later (or a display side of a pixel unit in a display device), and is, for example, a gradient index GRIN lens. In the lens 10, the shape of the surface (the shape of the light incident surface and the light exit surface) is not particularly limited, but is preferably a substantially flat surface as in the present embodiment. This makes it possible to easily stack lenses on the pixel portion. Although details will be described later, it is not necessary to form a film for flattening or adjusting the refractive index, and process easiness can be improved. In this specification, a “flat” or “substantially flat” surface includes a minute unevenness or a step generated in the process, and is not limited to a completely smooth surface without any unevenness. Absent.

  The surface of the lens 10 is substantially flat, and the shape of the surface perpendicular to the optical axis Z is, for example, square or rectangular. Alternatively, the surface shape may be a regular hexagonal shape, and in this case, a honeycomb structure can be formed as a whole by arranging and arranging a plurality of lenses 10. The lens 10 is obtained by laminating a lens layer 12 on a base layer 11. The light incident surface and the light emitting surface (surfaces S1, S2) of the lens layer 12 are substantially flat. In the present embodiment, the base layer 11 is made of an inorganic material, and the lens layer 12 is formed adjacent to the base layer 11.

  The lens 10 has a predetermined refractive index distribution in a plane perpendicular to the optical axis Z while having a flat surface as described above. That is, the refractive index (n1) (first refractive index) around the optical axis Z and at least a part of the refractive index (n2) (second refractive index) on the optical axis Z are different from each other. Here, for example, the refractive index change occurs substantially concentrically around the optical axis Z. Specifically, the refractive index is designed to be highest on the optical axis Z and gradually decrease from the optical axis Z toward the end e (according to the distance from the optical axis Z). Such a refractive index distribution is formed by thermal diffusion (or light diffusion) in a manufacturing process described later.

  The refractive indexes n1 and n2 can be set, for example, according to a plurality of types of resin materials (or those containing an inorganic material in the resin material) used in a manufacturing process described later. Here, the refractive index n1 <n2, and the lens 10 functions as a so-called convex lens. However, the magnitude relationship of the refractive index is not limited to this. That is, the refractive index n1> n2 and the lens 10 may function as a so-called concave lens. Examples of the resin material include a thermosetting resin, and the presence or absence of photosensitivity is not questioned. In addition, an inorganic material may be included, or a material that absorbs or reflects a selective wavelength (such as a metal ion) may be included. Moreover, not only a metal ion but a pigment | dye (organic pigment | dye) etc. may be used.

  The refractive indexes n1 and n2 can be set to various values according to the selected material. As an example, the refractive indexes n1 and n2 can be set to any one of 1.22, 1.74, 1.92 (1.916), and about 2.0 to 2.5.

For example, by using a hollow silica material or silicon oxide (SiO ₂ ) such as SiO ₂ Hybrid Siosol manufactured by Merck Co., Ltd. as the inorganic material, a refractive index of 1.22 can be realized. In addition, as an inorganic material, titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), tantalum oxide (Ta ₂ O ₅ ), niobium oxide (Nb ₂ O ₅ ), zinc oxide (ZnO), or silicon nitride (Si ₃ N) ) Or the like can be used to achieve a refractive index of about 2.0 to 2.5. Moreover, the lens layer 12 may contain multiple types among said inorganic materials. Further, by using, for example, an episulfide compound such as MR-174 manufactured by Mitsubishi Chemical Corporation or a metal-containing thietane compound such as IU-20 manufactured by Mitsubishi Gas Chemical Co., Ltd. as a resin material, a refractive index of about 1.74. Or about 1.92 is realizable. In addition, when a resin material (MR-174: refractive index 1.74) and an inorganic material (TiO ₂ : refractive index 2.4) are mixed at a ratio of 1: 1, a refractive index of 2.1 is obtained. Can do.

As the inorganic material, for example, at least one of metal oxide, silicon nitride, silicon oxide, nitrogen oxide (NO _x ), fluoride, sulfide, and nickel alloy can be used. Specifically, as an inorganic material, silver oxide (I) (Ag ₂ O), silver monoxide (AgO), aluminum oxide (Al ₂ O ₃ ), cerium oxide (IV) (CeO ₂ ), chromium oxide (III ) (Cr ₂ O ₃ ), hafnium oxide (IV) (HfO ₂ ), indium tin oxide (ITO), lithium niobate (LiNbO ₃ ), magnesium oxide (MgO), sodium hexafluoroaluminate (Na ₃ AlF ₆ ) Niobium oxide (Nb ₂ O ₅ ), tantalum oxide (Ta ₂ O ₅ ), titanium monoxide (TiO), titanium dioxide (TiO ₂ ), titanium trioxide (Ti ₂ O ₃ ), titanium pentoxide (Ti ₃ O) ₅ ), tungsten oxide (WO ₃ ), yttrium oxide (Y ₂ O ₃ ), zirconium oxide (ZrO ₂ ), indium oxide (In ₂ O ₃ ), zinc oxide (ZnO), silicon nitride (SiN _x ), monoxide Silicon (SiO), silicon dioxide (SiO ₂ ), aluminum fluoride (AlF ₃ ), barium fluoride (BaF ₂ ), gadolinium fluoride (GdF ₃ ), lanthanum fluoride (LaF ₃ ), magnesium fluoride (MgF ₂₎ ), Yttrium fluoride (YF ₃ ), chromium sulfide (III) (Cr ₂ S ₃ ), zinc sulfide (ZnS), nichrome (Ni—Cr), and nichrome nitride (NiCrN _x ) Including.

  Thus, the degree of freedom in selecting the refractive indexes n1 and n2 is large (the degree of freedom in material selection is large), and a large difference between the refractive indexes n1 and n2 can be secured.

[Production method]
The lens 10 having the above configuration can be manufactured, for example, as follows. 2A to 5D are schematic sectional views or schematic plan views for explaining the method of manufacturing the lens 10 in the order of steps.

  First, as shown in FIG. 2A, a first resin layer 12 </ b> A (first resin layer) is formed on the base layer 11 (it is cured after application). The first resin layer 12A is a resin layer that contributes to the refractive index n1 described above. Thus, by using a resin material, the applicability and processability of the material can be improved. Note that the first resin layer 12A may contain an inorganic material or a metal ion as described above in addition to the resin material, depending on the required value of the refractive index n1. By including metal ions, for example, the lens 10 can function as a color filter. Here, the first resin layer 12A is applied and formed, but the formation method of the first resin layer 12A is not limited to this. For example, the first resin layer 12 </ b> A may be formed by preparing a resin material (sheet or film) molded into a thin film and bonding the resin material onto the base layer 11.

  Subsequently, as shown in FIG. 2B, a photoresist film 110 serving as a mask is formed on the first resin layer 12A (hardened after application).

  Thereafter, as shown in FIG. 3A, a predetermined region is exposed to form an opening 110 a in the photoresist film 110. In the present embodiment, one opening 110a is formed on the optical axis Z (in a circular region centered on the optical axis Z).

  Next, as shown in FIG. 3B, for example, etching is performed to form, for example, a cylindrical recess H1 in the first resin layer 12A. Here, a selective region corresponding to the opening 110a of the photoresist 110 is removed from the first resin layer 12A. The recess H1 may or may not penetrate the first resin layer 12A until reaching the surface of the foundation layer 11. Here, the recessed part H1 has shown the state which penetrated 12 A of 1st resin layers. Note that, due to etching conditions and the like, the diameter of the recess H1 may be different between the upper side and the lower side in the depth direction. It is desirable that the formation area of the recess H1 be equal to or less than half of the formation area of the first resin layer 12A. This is because it becomes easier to form a desired refractive index difference. Furthermore, in the thickness direction parallel to the optical axis Z of the lens 10, a part of the first resin layer 12A may remain facing the bottom surface of the recess H1. In this case, it is desirable that the remaining thickness of the first resin layer 12A be equal to or less than the diameter of the recess H1. This is because it becomes easier to form a desired refractive index difference.

  Thereafter, as shown in FIG. 3C, the photoresist film 110 is removed.

  Subsequently, as shown in FIG. 4, the second resin layer 12B is embedded and formed in the recess H1 of the first resin layer 12A (hardened after application). The second resin layer 12B is a resin layer that contributes to the refractive index n2 described above. In addition to the resin material, the second resin layer 12B may contain an inorganic material or a metal ion as described above in accordance with the required value of the refractive index n2. Further, like the first resin layer 12A, by using a resin material, it is possible to improve the applicability and processability of the material.

  Next, as shown in FIG. 5A, by applying heat treatment or irradiating light, the component (resin component) of the second resin layer 12B (all or part of the second resin layer 12B, the same applies hereinafter) is applied. And diffused in the first resin layer 12A. Alternatively, all or some of the components of the first resin layer 12A are diffused into the second resin layer 12B. Alternatively, the components of the first resin layer 12A and the second resin layer 12B may diffuse to each other. In addition, about heat processing conditions or light irradiation conditions, what is necessary is just to set an appropriate thing according to the material used, refractive index, etc.

  Accordingly, as shown in FIG. 5B, the refractive index n1 (for example, high refractive index) on the optical axis Z, while the refractive index n2 (for example, low refractive index) around the optical axis Z. A rate distribution can be formed. 5C and 5D are schematic plan views corresponding to FIGS. 5A and 5B. Thus, the diffusion can smoothly change the refractive index from the optical axis Z toward the periphery, and the lens 10 can function as a convex lens. In the present embodiment, since the recess H1 is formed so as to penetrate the first resin layer 12A, the second resin layer 12B is concentric (radial) in any thickness direction parallel to the optical axis Z. In the first resin layer 12A. Therefore, a refractive index distribution can be generated in a plane perpendicular to the optical axis Z.

  As described above, regardless of the surface shape of the lens 10, the refractive index n1 around the optical axis Z and the refractive index n2 on the optical axis Z (n1 <n2) are within the plane perpendicular to the optical axis Z. A refractive index profile is produced. Thereby, even if the surface of the lens 10 is a substantially flat surface, for example, the lens function as a convex lens is exhibited.

  The surface of the lens 10 is macroscopically substantially flat as described above, but in reality, a minute step is formed on the surface as a trace due to formation of a recess using the etching (or imprint) and resin embedding. (Step St) occurs. This step corresponds to, for example, the vicinity of the outer periphery of the region B shown in FIG. 6A (that is, the region corresponding to the vicinity of the boundary between the first resin layer 12A and the second resin layer 12B, or the vicinity of the outer periphery of the recess H1). Area). In other words, the convex portion B1 (FIG. 6B) or the concave portion B2 (FIG. 6C) is formed in the region B according to the combination of the resin materials of the first resin layer 12A and the second resin layer 12B. Such a step is a surface shape that does not occur in a gradient index lens formed by ion implantation, for example, and is a specific surface shape formed through the manufacturing process of the present embodiment.

  As described above, in the present embodiment, a refractive index including a refractive index n1 around the optical axis Z and a refractive index n2 (n1 <n2) on the optical axis Z in a plane perpendicular to the optical axis Z. A distribution can be formed. Therefore, it is possible to easily realize a desired refractive index distribution while having a substantially flat surface shape.

  In addition, since the resin material used in the first resin layer 12A and the second resin layer 12B is not sensitive to the presence or absence of photosensitivity, the degree of freedom in material selection is high. In addition, a desired refractive index distribution can be easily designed according to the layout such as the position and size of the recess H1.

  Furthermore, since the degree of freedom of material selection increases, an inorganic material can be contained in the resin material, and thereby, for example, a larger difference in refractive index between the first resin layer 12A and the second resin layer 12B can be secured. it can. A refractive index distribution having a very large refractive index difference can be realized on a flat surface shape.

  In addition, since the degree of freedom of material selection is increased, the resin material can contain a material that absorbs or reflects a selective wavelength, and thus a color filter function can be added.

  In the present embodiment, the concave portion H1 is formed by etching, which is suitable when the lens 10 has a minute dimension (about several μm), for example. However, the etching method of the present embodiment can be applied even when the dimensions are larger than several μm.

  Hereinafter, modifications of the first embodiment and other embodiments will be described. In addition, the same code | symbol is attached | subjected about the thing similar to the component in the lens of the said 1st Embodiment, or the manufacturing method of a lens, and description is abbreviate | omitted suitably.

<Modification 1>
7A to 7C are schematic cross-sectional views for explaining the lens manufacturing method according to the first modification. In the first embodiment, the recess H1 is formed by etching. However, the method for forming the recess H1 is not limited to etching. For example, as in this modification, the recess H1 can be formed by imprinting (mold, nanoimprinting).

  Specifically, first, after forming the first resin layer 12A in the same manner as in the first embodiment, as shown in FIGS. 7A and 7B, from above the first resin layer 12A, The mold 120 is pressed. Thereafter, as shown in FIG. 7C, the mold 120 is detached from the first resin layer 12A, thereby forming a recess H1 on the optical axis Z (in a circular region centered on the optical axis Z). Thereby, the recessed part H1 can be formed in the selective area | region of 12 A of 1st resin layers similarly to the said 1st Embodiment. Subsequent steps (embedding step of second resin layer 12B, diffusion step) are the same as those in the first embodiment. Here, the first resin layer 12A is applied and formed, but as in the above-described embodiment, as the first resin layer 12A, for example, a resin material (sheet or film) formed into a thin film is used as the base layer 11. It may be pasted on top. In this case, the mold 120 may be pressed after the formed first resin layer 12A is softened by heat treatment or chemicals.

  As in this modification, the recess H1 may be formed by imprinting, and in this case as well, the same effect as that of the first embodiment can be obtained. However, this modified example is suitable when, for example, the lens 10 has a relatively large size (for example, several tens of μm or more). However, the imprint method according to the present embodiment can also be applied to a case where the dimension is smaller than several tens of micrometers, for example, a minute dimension of about several micrometers.

<Modification 2-1>
8A to 8C are schematic diagrams for explaining a method for manufacturing a lens according to Modification 2-1. However, in each figure, the left figure shows a cross-sectional configuration, and the right figure schematically shows a planar configuration. Note that the cross-sectional configuration in each figure corresponds to a cross-sectional view taken along the IB-IB line, IC-IC line, or ID-ID line of the planar configuration. In the first embodiment, only one concave portion H1 is formed on one lens 10, but the number of concave portions H1 is not limited to one. As in this modification, a plurality of recesses H1 may be formed.

  Specifically, first, after forming the first resin layer 12A in the same manner as in the first embodiment, as shown in FIG. 8A, a plurality of recesses H1 are formed in the pattern on the first resin layer 12A. To do. The method of forming the recess H1 may be the etching described above or imprint. The plurality of recesses H1 are formed at positions corresponding to the distance from the optical axis Z in a plane perpendicular to the optical axis Z. For example, the concave portion H1 is arranged so that the density (abundance ratio) gradually decreases as the distance from the optical axis Z increases (as the end portion is approached). Thereby, the abundance ratio of the second resin layer 12B embedded in the recess H1 also changes according to the distance from the optical axis Z.

  Thereafter, as shown in FIG. 8B, the second resin layer 12B is embedded in each of the plurality of recesses H1 in the same manner as in the first embodiment.

  Subsequently, in the same manner as in the first embodiment, the refractive index distribution as shown in FIG. 8C is obtained by diffusing the components of the second resin layer 12B into the first resin layer 12A by heat treatment or light irradiation. Can be formed. A convex lens that can obtain the same effects as those of the first embodiment, can control the refractive index change more precisely, and can smoothly change the refractive index from the optical axis Z to the end of the lens 10. It becomes possible to function as.

<Modification 2-2>
9A to 9C are schematic views for explaining a method for manufacturing a lens according to Modification 2-2. However, in each figure, the left figure shows a cross-sectional configuration, and the right figure schematically shows a planar configuration. In addition, the cross-sectional configuration in each figure corresponds to a cross-sectional view taken along the IE-IE line, IF-IF line, or IG-IG line of the planar configuration. In the first embodiment and the modified example 2-1, the second resin layer 12B is formed after forming the recess H1 in the first resin layer 12A. However, the first resin layer 12A and the second resin layer 12B are formed. The order of forming is not limited to this.

  For example, as shown in FIG. 9A, first, a columnar second resin layer 12B is pattern-formed at a plurality of locations on the base layer 11 as in this modification. Specifically, after forming the second resin layer 12B on the base layer 11, patterning is performed by, for example, etching or imprinting. In other words, the convex portions formed of the plurality of second resin layers 12B are discretely formed on the base layer 11.

  Thereafter, as shown in FIG. 9B, the first resin layer 12A is formed so as to fill the gaps between the plurality of second resin layers 12B (so as to surround the second resin layer 12B). Subsequently, as in the first embodiment and the modified example 2-1, the refractive index distribution as shown in FIG. 9C is obtained by diffusing the components of the second resin layer 12B into the first resin layer 12A. Can be formed. Even when formed in this way, the same effects as those of the first embodiment and the modified example 2-1 can be obtained.

<Second Embodiment>
FIG. 10 schematically illustrates a cross-sectional configuration of a lens (lens 10 </ b> A) according to the second embodiment of the present disclosure. In the first embodiment, the refractive index distribution is formed only in the plane perpendicular to the optical axis Z. However, as in the present embodiment, the refractive index distribution is also refracted in the thickness direction parallel to the optical axis Z. A rate distribution may be formed. The lens 10 </ b> A has a substantially flat surface shape and a lens layer 13 laminated on the base layer 11, as in the first embodiment. The lens layer 13 has a refractive index distribution both in the plane perpendicular to the optical axis Z and in the thickness direction parallel to the optical axis Z.

  The refractive index distribution in the thickness direction has a high refractive index between the light incident surface and the light emitting surface (surfaces S1, S2) of the lens layer 13, for example, at a predetermined depth from the surface S2, and in a portion deeper than that. The distribution is such that the refractive index gradually decreases toward the surface S1. That is, on the optical axis Z, in the vicinity of the surface S1, the refractive index is close to n1, and in the portion from the predetermined depth to the surface S2, the refractive index is n2. Such a refractive index distribution in the thickness direction is also formed by thermal diffusion (or light diffusion) in the manufacturing process, like the refractive index distribution in the plane perpendicular to the optical axis Z.

  Also in the present embodiment, as in the first embodiment, the lens layer 13 may contain an inorganic material together with a resin material (for example, a thermosetting resin) or absorb a selective wavelength. Alternatively, a reflective material (such as metal ions) may be included. Moreover, not only a metal ion but a pigment | dye (organic pigment | dye) etc. may be used.

  This lens 10A can be manufactured as follows, for example. 11A to 13B are schematic cross-sectional views for explaining the method of manufacturing the lens 10A in the order of steps.

  First, in the same manner as in the first embodiment, after forming the first resin layer 12A on the base layer 11, the photoresist film 110 having the opening 110a is formed on the first resin layer 12A. To do. Subsequently, as shown in FIG. 11A, for example, etching is performed to form, for example, a cylindrical recess H2 in the first resin layer 12A. At this time, the recess H2 removes the first resin layer 12A to a predetermined depth t, and stops etching. That is, the recess H2 is formed so that the depth thereof is shallower than the thickness of the first resin layer 12A. Further, it is desirable that the thickness of the first resin layer 12A facing the bottom surface of the recess H2 is equal to or smaller than the diameter of the recess H2. This is because it becomes easier to form a desired refractive index difference. Thereafter, as shown in FIG. 11B, the photoresist film 110 is removed.

  Subsequently, as shown in FIG. 12, the second resin layer 12B is embedded and formed in the recess H2 of the first resin layer 12A (hardened after application).

  Next, as shown in FIG. 13A, in the same manner as in the first embodiment, heat treatment is performed or light is irradiated so that the components of the second resin layer 12B are contained in the first resin layer 12A. To diffuse. Accordingly, as shown in FIG. 13B, a refractive index distribution that changes from a refractive index n1 (for example, a low refractive index) to a refractive index n2 (for example, a high refractive index) can also be formed in the thickness direction. In this way, by adjusting the depth of the recess H2, a desired refractive index distribution can be formed in each of the in-plane direction perpendicular to the optical axis Z and the thickness direction. Thereby, even if the surface shape of the lens 10A is substantially flat, the lens 10A can function as, for example, a convex lens. Further, finer refractive index control can be easily realized by controlling the refractive index in the thickness direction.

<Modification 3>
14A to 16 are schematic cross-sectional views for explaining a lens manufacturing method according to Modification 3. In the second embodiment, only one concave portion H2 is formed for one lens 10A, but the number of concave portions H2 is not limited to one. As in this modification, a plurality of recesses (recesses H2a to H2d) may be formed. Further, the formation positions and depths of the recesses H2a to H2d may be set according to the distance from the optical axis Z.

  Specifically, after the first resin layer 12A is formed in the same manner as in the second embodiment, first, as shown in FIG. 14A, at the position on the optical axis Z of the first resin layer 12A, Using the photoresist film 110a as a mask, a recess H2a having a predetermined depth is formed. The method of forming the recess H2a may be the above-described etching or imprinting, but here, the case of etching is illustrated. In this case, as will be described below, etching is performed a plurality of times in order to change the depths of the recesses H2a to H2d.

  Subsequently, as shown in FIG. 14B, after further patterning the photoresist film 110a, a recess H2b is formed by etching around the recess H2a so that the depth is smaller than the recess H2a. A plurality of the recesses H2b can be formed so as to surround the recess H2a, for example. In addition, when the recess H2b is etched, the previously formed recess H2a is also etched, and the depth of the recess H2b is increased. Similarly, as shown in FIG. 14C, after the photoresist film 110a is further patterned, a recess H2c is formed by etching around the recess H2b so that the depth is smaller than that of the recess H2b. A plurality of the recesses H2c can be formed so as to surround the recess H2b, for example. In the etching of the recess H2c, the etching of the previously formed recesses H2a and H2b also proceeds. Similarly, as shown in FIG. 14D, after the photoresist film 110a is further patterned, a recess H2d is formed by etching around the recess H2c so that the depth is smaller than the recess H2c. A plurality of the recesses H2d can be formed so as to surround the recess H2c, for example. Further, during the etching of the recess H2d, the etching of the previously formed recesses H2a to H2c also proceeds. In this way, the plurality of recesses H2a to H2d can be formed so that the depth gradually decreases as the distance from the optical axis Z increases. In addition, as in Modification 2-1, the formation positions of the plurality of recesses H2a to H2d may be changed according to the distance from the optical axis Z.

  Thereafter, the photoresist film 110a is peeled off, and as shown in FIG. 15, the second resin layer 12B is embedded in each of the plurality of recesses H2a to H2d in the same manner as in the first embodiment. .

  Subsequently, in the same manner as in the first embodiment, the refractive index distribution as shown in FIG. 16 is obtained by diffusing the components of the second resin layer 12B into the first resin layer 12A by heat treatment or light irradiation. Can be formed. The same effects as those of the first embodiment can be obtained, and the refractive index can be arbitrarily controlled in the plane perpendicular to the optical axis Z and in the thickness direction. The degree of freedom in controlling the refractive index is high, and the lens can function as a convex lens that changes the refractive index more smoothly.

<Modification 4>
17 and 18 are schematic cross-sectional views for explaining a method for manufacturing a lens according to Modification 4. In the modification 3, by controlling the formation position and depth of the plurality of recesses (recesses H2a to H2d), arbitrary refractive index control is possible in each of the in-plane direction and the thickness direction. It is possible to design a so-called aspherical shape as in this modification.

  Specifically, as shown in FIG. 17, the formation positions and depths of the recesses H <b> 2 a to H <b> 2 d may be set to an arbitrary depth according to the distance from the optical axis Z. Here, as an example, the depth of the recess H2d disposed on the outermost periphery among the recesses H2a to H2d is formed to be larger than the recess H2c. By embedding and diffusing the second resin layer 12B in the recesses H2a to H2d, a refractive index distribution that can function as an aspheric lens (convex aspheric lens) as shown in FIG. 18 can be formed. .

<Modification 5>
19 and 20 are schematic diagrams for explaining a method for manufacturing a lens according to Modification 5. However, in each figure, the left figure shows a cross-sectional configuration, and the right figure schematically shows a planar configuration. The cross-sectional configuration in each figure corresponds to a cross-sectional view taken along the IH-IH line or II-II line of the planar configuration. In the above-described embodiment and the like, the refractive index distribution is formed in the biaxial direction in the plane perpendicular to the optical axis Z, but the distribution does not necessarily have to be formed in the biaxial direction. As in this modification, the refractive index distribution may be formed only along one axis in the in-plane direction.

  Specifically, after the first resin layer 12A is formed in the same manner as in the first and second embodiments, first, in the plane perpendicular to the optical axis Z, as shown in FIG. A recess H3 is formed so as to extend along (in a stripe shape), and the second resin layer 12B is embedded in the recess H3. The method for forming the recess H3 may be etching or imprint as described above. Further, the recess H3 may penetrate the first resin layer 12A or may be formed at a predetermined depth (a depth smaller than the thickness of the first resin layer 12A). The example formed in the depth of is shown.

  Thereafter, the lens layer 14 having a refractive index distribution as shown in FIG. 20 is obtained by diffusing the components of the second resin layer 12B in the first resin layer 12A in the same manner as in the first and second embodiments. Can be formed. That is, it becomes possible to function as a so-called cylindrical lens having a refractive index distribution only along one axis in the in-plane direction.

<Modification 6>
FIG. 21 is a schematic diagram for explaining a configuration of a lens according to Modification 6. In the first embodiment, the lens layer 12 is laminated adjacent to the base layer 11 made of an inorganic material. However, when the base layer 11 is made of an organic material, an inorganic material is used as in this modification. A protective film 15 made of a material may be interposed. This is because when the underlayer 11 is made of an organic material, the underlayer 11 is easily affected (damaged) when forming the refractive index distribution of the lens layer 12. Therefore, it is desirable to form the lens layer 12 on the base layer 11 via the protective film 15. The inorganic material used for the protective film 15 is more preferably a hard material.

<Application example>
The lens 10 (or the lens 10 </ b> A) described in the above-described embodiment and the like is preferably used in, for example, an imaging device or a display device. FIG. 22 schematically shows an overall configuration of an imaging apparatus (same for display apparatus) 1 according to an application example. As described above, the imaging apparatus 1 includes, for example, the pixel unit 1A as an imaging area and the peripheral circuit unit 1B for driving the pixel unit 1A.

  The pixel unit 1A has, for example, a plurality of pixels that are two-dimensionally arranged in a matrix, and includes, for example, a CCD or a CMOS image sensor. Various signal wirings (not shown) are connected to each pixel, for example, for each pixel row and each pixel column. Various signal wirings are connected to corresponding output terminals or input terminals in the peripheral circuit section 1B.

  In such a configuration, the lens 10 described above is provided as, for example, a so-called on-chip lens on the light receiving side (display side in the case of a display device) of the pixel unit 1A, for example, facing at least the pixel unit 1A. Specifically, the lens 10 is selectively provided only in a region facing the pixel unit 1A among the pixel unit 1A and the peripheral circuit unit 1B, or opposed to both the pixel unit 1A and the peripheral circuit unit 1B. Is provided. In the latter case, since the peripheral circuit portion 1B is shielded from light, there is no problem even if the lens 10 is disposed. In addition, the lens 10 may be provided for each pixel, or one lens (across a plurality of pixels) may be provided for a plurality of pixels.

  In the imaging device 1, by providing the lens 10 as described above, it is possible to form a desired refractive index distribution while making the lens surface flat. This eliminates the need to provide a low refractive index planarization layer on the surface of the high refractive index concavo-convex lens array, improving process easiness. Moreover, generation | occurrence | production of the diffracted light by an unevenness | corrugation can be suppressed. Furthermore, the refractive index distribution can be easily formed up to the four corners in the in-plane direction of the lens 10, and the amount of received light can be increased. On the other hand, when the lens 10 is applied to a display device, it is not necessary to provide a low refractive index layer such as a protective glass on the surface of the high refractive index concavo-convex lens array, and the processability is improved.

  As described above, the embodiments and modifications have been described, but the present disclosure is not limited to the above-described embodiments and the like, and various modifications can be made. For example, in the above-described embodiment and the like, the refractive index distribution is formed so as to have a high refractive index on the optical axis and a low refractive index on the periphery, but a reverse combination may be used. That is, a refractive index distribution may be formed so as to have a low refractive index on the optical axis and a high refractive index in the periphery, and function as a concave lens.

  In the above-described embodiment and the like, the refractive index distribution is formed using two types of material layers (first resin layer 12A and second resin layer 12B). However, three or more types of material layers may be used. Good. In addition, the effect demonstrated in the said embodiment etc. is an example, The other effect may be sufficient and the other effect may be included.

The present disclosure may be configured as follows.
(1)
In a plane perpendicular to the optical axis,
A first refractive index around the optical axis;
A lens having a refractive index distribution including: a second refractive index different from the first refractive index in at least a part of the optical axis.
(2)
The lens according to (1), wherein the surface has a minute step.
(3)
A second resin layer having a refractive index different from that of the first resin layer is embedded in the concave portion of the first resin layer having a concave portion, and one of the first and second resin layers is formed by heat treatment or light irradiation. By diffusing at least one component into the other, the refractive index distribution is formed,
The lens according to (2), wherein the step is generated in a region corresponding to a vicinity of a boundary between the first and second resin layers.
(4)
The lens according to (3), wherein the recess is formed by etching or imprinting.
(5)
Having a resin material and an inorganic material,
The inorganic material includes at least one of metal oxide, silicon nitride, silicon oxide, nitrogen oxide, fluoride, sulfide, and nickel alloy, according to any one of (1) to (4). Lens.
(6)
The inorganic material includes silver (I) oxide (Ag ₂ O), silver monoxide (AgO), aluminum oxide (Al ₂ O ₃ ), cerium (IV) oxide (CeO ₂ ), chromium (III) oxide (Cr ₂ O ₃ ), hafnium oxide (IV) (HfO ₂ ), indium tin oxide (ITO), lithium niobate (LiNbO ₃ ), magnesium oxide (MgO), sodium hexafluoroaluminate (Na ₃ AlF ₆ ), niobium oxide ( Nb ₂ O ₅ ), tantalum oxide (Ta ₂ O ₅ ), titanium monoxide (TiO), titanium dioxide (TiO ₂ ), titanium trioxide (Ti ₂ O ₃ ), titanium pentoxide (Ti ₃ O ₅ ), oxidation Tungsten (WO ₃ ), yttrium oxide (Y ₂ O ₃ ), zirconium oxide (ZrO ₂ ), indium oxide (In ₂ O ₃ ), zinc oxide (ZnO), silicon nitride (SiN _x ), silicon monoxide (S iO), silicon dioxide (SiO ₂ ), aluminum fluoride (AlF ₃ ), barium fluoride (BaF ₂ ), gadolinium fluoride (GdF ₃ ), lanthanum fluoride (LaF ₃ ), magnesium fluoride (MgF ₂ ), Including at least one of yttrium fluoride (YF ₃ ), chromium sulfide (III) (Cr ₂ S ₃ ), zinc sulfide (ZnS), nichrome (Ni—Cr) and nichrome nitride (NiCrN _x ) The lens according to any one of (1) to (5).
(7)
A lens layer having the refractive index profile;
An underlayer of the lens layer,
The underlayer is composed of an inorganic material;
The lens according to any one of (1) to (6), wherein the lens layer is formed adjacent to the base layer.
(8)
A lens layer having the refractive index profile;
An underlayer of the lens layer,
The underlayer is made of an organic material;
The lens according to any one of (1) to (6), wherein the lens layer is formed on the base layer via a protective film made of an inorganic material.
(9)
The lens according to any one of (1) to (8), which has a material that absorbs or reflects a selective wavelength.
(10)
The lens according to any one of (1) to (9), wherein a refractive index changes along a direction parallel to the optical axis.
(11)
A refractive index distribution including a first refractive index in the vicinity of the optical axis and a second refractive index different from the first refractive index in at least a part on the optical axis in a plane perpendicular to the optical axis. A method for manufacturing a lens.
(12)
Forming a recess in the first resin layer having a predetermined refractive index;
A second resin layer having a refractive index different from that of the first resin layer is embedded in the recess,
The method for manufacturing a lens according to (11), wherein the refractive index distribution is formed by diffusing at least one of the first and second resin layers into the other by heat treatment or light irradiation.
(13)
The method for manufacturing a lens according to (12), wherein the concave portion is formed by etching or imprinting.
(14)
The method for manufacturing a lens according to (13), wherein the diameter of the concave portion is different between the upper side and the lower side.
(15)
The method for manufacturing a lens according to any one of (12) to (14), wherein a formation area of the recess is less than or equal to a half of a formation area of the first resin layer.
(16)
The method for producing a lens according to any one of (12) to (15), wherein the concave portion is formed shallower than a thickness of the first resin layer.
(17)
The method for manufacturing a lens according to any one of (12) to (16), wherein a thickness of the first resin layer facing a bottom surface of the recess is not more than a diameter of the recess.
(18)
Forming a plurality of the recesses;
The method for manufacturing a lens according to any one of (12) to (17), wherein formation positions of the plurality of concave portions in a plane perpendicular to the optical axis are changed according to a distance from the optical axis.
(19)
Forming a plurality of the recesses;
The method for manufacturing a lens according to any one of (12) to (18), wherein the depths of the plurality of recesses are changed according to a distance from the optical axis.
(20)
Patterning a second resin layer having a predetermined refractive index in a selective region;
Forming a first resin layer having a refractive index different from that of the second resin layer so as to surround the formed second resin layer;
The method for manufacturing a lens according to (11), wherein the refractive index distribution is formed by diffusing the second resin layer into the first resin layer by heat treatment or light irradiation.
(21)
A refractive index distribution including a first refractive index in the vicinity of the optical axis and a second refractive index different from the first refractive index in at least a part on the optical axis in a plane perpendicular to the optical axis. An imaging device comprising a lens.
(22)
A pixel portion including a plurality of pixels;
A circuit unit provided around the pixel unit,
The imaging device according to (21), wherein the lens is provided in at least the pixel portion of the pixel portion and the peripheral portion.
(23)
A refractive index distribution including a first refractive index in the vicinity of the optical axis and a second refractive index different from the first refractive index in at least a part on the optical axis in a plane perpendicular to the optical axis. A display device comprising a lens.
(24)
A pixel portion including a plurality of pixels;
A circuit unit provided around the pixel unit,
The display device according to (23), wherein the lens is provided in at least the pixel portion of the pixel portion and the peripheral portion.

  DESCRIPTION OF SYMBOLS 1 ... Imaging device (display apparatus), 1A ... Pixel part, 1B ... Peripheral circuit part, 10 ... Lens, 11 ... Underlayer, 12, 13, 14 ... Lens layer, 12A ... 1st resin layer, 12B ... 2nd resin Layer, 15 ... protective film, H1, H2, H2a, H2b, H2c, H2d, H3 ... recess.

Claims (23)

In a plane perpendicular to the optical axis,
A first refractive index around the optical axis;
A lens having a refractive index distribution including: a second refractive index different from the first refractive index in at least a part of the optical axis. The lens according to claim 1, wherein the surface has a minute step. A second resin layer having a refractive index different from that of the first resin layer is embedded in the concave portion of the first resin layer having a concave portion, and one of the first and second resin layers is formed by heat treatment or light irradiation. By diffusing at least one component into the other, the refractive index distribution is formed,
The lens according to claim 2, wherein the step is generated in a region corresponding to a vicinity of a boundary between the first and second resin layers. The lens according to claim 3, wherein the concave portion is formed by etching or imprinting. Having a resin material and an inorganic material,
The lens according to claim 1, wherein the inorganic material includes at least one of metal oxide, silicon nitride, silicon oxide, nitrogen oxide, fluoride, sulfide, and nickel alloy. The inorganic material includes silver (I) oxide (Ag ₂ O), silver monoxide (AgO), aluminum oxide (Al ₂ O ₃ ), cerium (IV) oxide (CeO ₂ ), chromium (III) oxide (Cr ₂ O ₃ ), hafnium oxide (IV) (HfO ₂ ), indium tin oxide (ITO), lithium niobate (LiNbO ₃ ), magnesium oxide (MgO), sodium hexafluoroaluminate (Na ₃ AlF ₆ ), niobium oxide ( Nb ₂ O ₅ ), tantalum oxide (Ta ₂ O ₅ ), titanium monoxide (TiO), titanium dioxide (TiO ₂ ), titanium trioxide (Ti ₂ O ₃ ), titanium pentoxide (Ti ₃ O ₅ ), oxidation Tungsten (WO ₃ ), yttrium oxide (Y ₂ O ₃ ), zirconium oxide (ZrO ₂ ), indium oxide (In ₂ O ₃ ), zinc oxide (ZnO), silicon nitride (SiN _x ), silicon monoxide (S iO), silicon dioxide (SiO ₂ ), aluminum fluoride (AlF ₃ ), barium fluoride (BaF ₂ ), gadolinium fluoride (GdF ₃ ), lanthanum fluoride (LaF ₃ ), magnesium fluoride (MgF ₂ ), It contains at least one of yttrium fluoride (YF ₃ ), chromium sulfide (III) (Cr ₂ S ₃ ), zinc sulfide (ZnS), nichrome (Ni—Cr) and nichrome nitride (NiCrN _x ). Item 6. The lens according to Item 5. A lens layer having the refractive index profile;
An underlayer of the lens layer,
The underlayer is composed of an inorganic material;
The lens according to claim 1, wherein the lens layer is formed adjacent to the base layer. A lens layer having the refractive index profile;
An underlayer of the lens layer,
The underlayer is made of an organic material;
The lens according to claim 1, wherein the lens layer is formed on the base layer via a protective film made of an inorganic material. The lens according to claim 1, comprising a material that absorbs or reflects a selective wavelength. The lens according to claim 1, wherein a refractive index changes along a direction parallel to the optical axis. A refractive index distribution including a first refractive index in the vicinity of the optical axis and a second refractive index different from the first refractive index in at least a part on the optical axis in a plane perpendicular to the optical axis. A method for manufacturing a lens. Forming a recess in the first resin layer having a predetermined refractive index;
A second resin layer having a refractive index different from that of the first resin layer is embedded in the recess,
The lens manufacturing method according to claim 11, wherein the refractive index distribution is formed by diffusing at least one component of the first and second resin layers into the other by heat treatment or light irradiation. The lens manufacturing method according to claim 12, wherein the recess is formed by etching or imprinting. The method for manufacturing a lens according to claim 12, wherein the diameter of the concave portion is different between the upper side and the lower side. The method for manufacturing a lens according to claim 12, wherein a formation area of the concave portion is equal to or less than a half of a formation area of the first resin layer. The method for manufacturing a lens according to claim 12, wherein the concave portion is formed shallower than a thickness of the first resin layer. The lens manufacturing method according to claim 12, wherein a thickness of the first resin layer facing a bottom surface of the concave portion is equal to or less than a diameter of the concave portion. Forming a plurality of the recesses;
The lens manufacturing method according to claim 12, wherein the formation positions of the plurality of concave portions in a plane perpendicular to the optical axis are changed according to a distance from the optical axis. Forming a plurality of the recesses;
The lens manufacturing method according to claim 12, wherein the depths of the plurality of concave portions are changed according to a distance from the optical axis. Patterning a second resin layer having a predetermined refractive index in a selective region;
Forming a first resin layer having a refractive index different from that of the second resin layer so as to surround the formed second resin layer;
The lens manufacturing method according to claim 11, wherein the refractive index distribution is formed by diffusing at least one of the first and second resin layers into the other by heat treatment or light irradiation. A refractive index distribution including a first refractive index in the vicinity of the optical axis and a second refractive index different from the first refractive index in at least a part on the optical axis in a plane perpendicular to the optical axis. An imaging device comprising a lens. A pixel portion including a plurality of pixels;
A circuit unit provided around the pixel unit,
The imaging device according to claim 21, wherein the lens is provided in at least the pixel portion of the pixel portion and the peripheral portion. A refractive index distribution including a first refractive index in the vicinity of the optical axis and a second refractive index different from the first refractive index in at least a part on the optical axis in a plane perpendicular to the optical axis. A display device comprising a lens.