JP2018005230A - Optical filter, display device, image pickup device, and method for manufacturing optical filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical filter, a display device, an image pickup device, and an optical filter capable of increasing the degree of freedom of adjusting the distribution of the wavelength region of light transmitted through the filter element in the filter element. A periodic element included in a periodic structure is either a protrusion 11T having one end on a reference surface and projecting from the reference surface, or a hole having one end on the reference surface and being recessed from the reference surface. On the other hand. The metal layer includes a first metal layer 23 having a mesh shape surrounding one end of each periodic element in the reference plane, and a second metal layer 42 located at the other end of each periodic element. The structural period of the periodic element is a sub-wavelength period, and the ratio of the width of the periodic element to the structural period is 0.30 or more and 0.65 or less. In the metal layer, the real part of the complex permittivity with respect to light in the visible region is a negative value, and the thickness of the metal layer is 1/10 or less of the distance between one end and the other end in each periodic element. .. [Selection diagram] Fig. 3

Description

  The present invention relates to an optical filter, a display device, an imaging device, and a method for manufacturing an optical filter.

  A display device such as a liquid crystal display device or an organic EL (Electro Luminescence) display device includes a color filter which is an example of an optical filter. The color filter converts white light emitted from the light source into one color for each sub-pixel, or corrects colored light emitted from the light source into one color for each sub-pixel. The color filter includes, for example, a black matrix that partitions each sub-pixel one by one, and a color conversion unit that is located in a region partitioned by the black matrix (see, for example, Patent Document 1).

JP 2014-098780 A

  By the way, the color conversion part mentioned above is a single thin film layer that absorbs light in a predetermined wavelength region, and the color after color conversion by the color conversion part is darker as the thickness of the thin film layer is thicker. On the other hand, the thickness of the thin film layer varies in the thin film layer, and may be thick at the edge of the thin film layer or thick at the center of the thin film layer. It is difficult to adjust the thickness of the thin film layer to a desired distribution in the sub-pixel, and the color filter described above has a degree of freedom to adjust the distribution of the wavelength region that the sub-pixel selectively transmits in the sub-pixel. I do not have.

  Such a problem is not limited to the color filter used in the display device, but is common in an optical filter including a filter element that transmits light in a specific wavelength region among light emitted from a light source.

  The present invention provides an optical filter, a display device, an imaging element, and an optical filter manufacturing method capable of increasing the degree of freedom in adjusting the distribution of the wavelength region of light transmitted through the filter element within the filter element. For the purpose.

  An optical filter that solves the above problem includes a plurality of filter elements that selectively transmit light in a specific wavelength region, and the filter element is a periodic structure made of a dielectric, and is a two-dimensional lattice shape. The periodic structure having a plurality of periodic elements arranged in a row, and a metal layer located on the surface of the periodic structure, wherein a plane in which the plurality of periodic elements are arranged in the periodic structure is a reference plane, The periodic element is either one of a protrusion having one end on the reference surface and projecting from the reference surface, and a hole having one end on the reference surface and recessed from the reference surface, The metal layer includes a first metal layer having a mesh shape surrounding the one end of each periodic element in the reference plane, and a second metal layer located at the other end of each periodic element, The wavelength at which the structural period of the periodic element is transmitted by the filter element A sub-wavelength period below a region, a ratio of the width of the periodic element to the structural period in each direction along the two-dimensional grating is 0.30 or more and 0.65 or less, and the metal layer is visible The real part of the complex permittivity for light in the region is a negative value, and the thickness of the metal layer is equal to or less than one-tenth of the distance between the one end and the other end of the periodic element.

  In the optical filter, a virtual layer along the reference plane and including the first metal layer is a first lattice layer, and the interface between the metal layer and the dielectric is a sub-wavelength in the first lattice layer. Repeated in a cycle. Further, the virtual layer along the reference plane and including the plurality of second metal layers is the second lattice layer, and even in the second lattice layer, the interface between the metal layer and the dielectric has a sub-wavelength period. Is repeated. In the first lattice layer and the second lattice layer, a part of light incident on the layer is coupled with collective vibration of electrons, that is, plasmon resonance occurs. In the first lattice layer, part of the light incident on the first lattice layer is converted into surface plasmons by plasmon resonance, and the surface plasmons are transmitted through the first lattice layer. Also in the second lattice layer, a part of the light incident on the second lattice layer is converted into surface plasmon by plasmon resonance and is transmitted through the second lattice layer. The surface plasmon transmitted through the first lattice layer or the second lattice layer is reconverted into light and emitted.

At this time, the ratio of the width of the periodic element to the structural period is 0.30 or more and 0.65 or less, and the thickness of the metal layer is 10 minutes of the distance between one end and the other end of each periodic element. Therefore, light transmission is ensured in both the first metal layer and the second metal layer. Further, the wavelength region of light transmitted through the first lattice layer and the wavelength region of light transmitted through the second lattice layer vary depending on the size of the structural period and the thickness of the periodic element. As a result, colored light other than black or white is emitted from the filter element. Since the wavelength region of light transmitted through the filter element is determined by the position and size of each periodic element and the metal layer whose position is determined by each periodic element, the distribution of the wavelength region of light transmitted through the filter element is determined by the filter element. The degree of freedom of adjustment can be increased.
The said structure WHEREIN: 100 nm or more and 200 nm or less may be sufficient as the distance of the said one end part in the said periodic element, and the said other end part.

According to the said structure, the distance of the one end part and other end part of a periodic element, and the thickness of the metal layer determined according to it are the magnitude | sizes which permeate | transmit the light which injects into a filter element fully. Therefore, it is possible to further increase the intensity of light transmitted through the filter element and the vividness of the color.
In the above configuration, the thickness of the metal layer may be 15 nm or less.
According to the said structure, since the thickness of a metal layer is thin enough, it is possible to fully ensure the intensity | strength of the light which a filter element permeate | transmits.

In the above configuration, the periodic element may be the protrusion, and a ratio of the width of the periodic element to the structural period in each direction along the two-dimensional lattice may be 0.5 or less.
According to the said structure, the intensity | strength of the light which a filter element permeate | transmits is raised.
In the above configuration, the material forming the metal layer may include any one metal material selected from the group consisting of aluminum, tantalum, silver, and gold.

  According to the above configuration, since the material constituting the metal layer is a material that easily causes plasmon resonance, the wavelength selectivity in the first lattice layer and the second lattice layer can be increased. Therefore, the selectivity of the wavelength of light transmitted through the filter element can be increased.

  In the above configuration, the dielectric layer is located on the surface of the metal layer and has a shape that follows the surface shape of the metal layer, and the thickness of the dielectric layer is different from the one end of the periodic element and the one of the periodic elements. It may be less than or equal to the distance from the other end.

According to the said structure, the wavelength range of the light which a filter element permeate | transmits can be adjusted with the change of the material which comprises a dielectric material layer. Therefore, the degree of freedom for adjusting the wavelength region of light transmitted through the filter element is further increased.
In the above configuration, the dielectric layer may have a thickness of 200 nm or less.
According to the said structure, the intensity | strength of the light which a filter element permeate | transmits is raised.

  In the above configuration, the material constituting the dielectric layer may include an oxide of any one material selected from the group consisting of titanium, niobium, aluminum, tantalum, hafnium, zirconium, silicon, and magnesium.

  According to the above configuration, the refractive index of the dielectric layer can be selected from a wide range as compared with the case where the dielectric layer is made of resin. Therefore, the degree of freedom for adjusting the wavelength region of light transmitted through the filter element is further increased.

  In the above-described configuration, the optical filter is a filter provided in a display device, and the plurality of filter elements provided in the optical filter selectively transmit a plurality of types of light in a wavelength region specific to each type. A filter element may be included.

According to the above configuration, in the color filter provided in the display device, the degree of freedom for adjusting the distribution of the wavelength region of the light transmitted by the filter element that functions as a subpixel is increased.
In the above configuration, the optical filter may be a filter provided in an image sensor.
According to the above configuration, in the filter provided in the image sensor, the degree of freedom for adjusting the distribution of the wavelength region of the light transmitted by the filter element is increased.
A display device that solves the above problem includes the optical filter and a light source device that causes light in a visible region to enter the filter element.

According to the above configuration, a display device including an optical filter in which the filter element of the optical filter functions as a sub-pixel and the degree of freedom for adjusting the distribution of the wavelength region of light transmitted by such a filter element is increased is realized.
An image pickup device that solves the above problem includes the optical filter and a light receiving element that receives light transmitted through the filter element and converts the light into an electric signal.
According to the above configuration, an imaging element including an optical filter with an increased degree of freedom for adjusting the distribution of the wavelength region of light transmitted through the filter element is realized.

  An optical filter manufacturing method that solves the above-described problem is an optical filter manufacturing method including a plurality of filter elements that selectively transmit light in a specific wavelength region, and the step of forming the filter element includes a base material By transferring the unevenness of the intaglio to the resin coated on the surface of the substrate, the periodic element that is a protrusion or a hole with a bottom as viewed from the direction facing the surface of the substrate is transmitted through the filter element. A periodic structure located in a two-dimensional lattice having a sub-wavelength period equal to or less than the wavelength region, the width of the periodic element with respect to the structural period of the periodic element in each direction along the two-dimensional grating A first step of forming the periodic structure having a ratio of 0.30 or more and 0.65 or less; and a metal layer having a shape following the surface shape of the periodic structure on the periodic structure. And light in the visible region A distance between one end of the periodic element and the other end of the periodic element that is located on a plane in which the plurality of periodic elements are arranged in the periodic structure, the metal layer having a negative real part of the complex permittivity And a second step of forming to a thickness of 1/10 or less.

  According to the said manufacturing method, in the optical filter, the freedom degree which adjusts distribution of the wavelength range of the light which a filter element permeate | transmits within a filter element is acquired highly. In addition, a periodic structure having fine irregularities can be easily and suitably formed.

  In the above manufacturing method, a dielectric layer having a shape following the surface shape of the metal layer is formed on the metal layer so as to have a thickness equal to or less than a distance between the one end and the other end of the periodic element. A third step may be included.

  According to the said manufacturing method, the wavelength range of the light which a filter element permeate | transmits can be adjusted with the change of the material which comprises a dielectric material layer. Therefore, the degree of freedom for adjusting the wavelength region of light transmitted through the filter element can be further increased.

  ADVANTAGE OF THE INVENTION According to this invention, the freedom degree which adjusts distribution of the wavelength range of the light which a filter element permeate | transmits within a filter element can be raised.

The top view which shows the planar structure in 1st Embodiment of a display apparatus. FIG. 3 is an enlarged view illustrating an enlarged planar structure of subpixels included in the color filter of the first embodiment. It is a figure which shows the cross-section of the subpixel of 1st Embodiment, and is the III-III sectional view taken on the line of FIG. It is a figure which shows the cross-section of the subpixel of 1st Embodiment, and is the IV-IV sectional view taken on the line of FIG. Sectional drawing which shows the other example of the cross-section of the subpixel of 1st Embodiment. FIG. 6 is an operation diagram illustrating an operation of the color filter of the first embodiment when the light source device is not lit. FIG. 5 is an operation diagram illustrating an operation of the color filter of the first embodiment when the light source device is turned on. FIG. 3 is an enlarged cross-sectional view illustrating an example of a part of the cross-sectional structure in the sub-pixel according to the first embodiment. Sectional drawing which expands and shows a part of sectional structure in the subpixel of the modification of 1st Embodiment. Sectional drawing which expands and shows a part of sectional structure in the subpixel of the modification of 1st Embodiment. The figure which shows the structure of the image pick-up element to which the structure of 1st Embodiment is applied. It is a figure which shows the cross-section of the subpixel in 2nd Embodiment of a color filter, and is the III-III sectional view taken on the line of FIG. It is a figure which shows the cross-section of the subpixel of 2nd Embodiment, and is the IV-IV sectional view taken on the line of FIG. The operation | movement figure which shows the effect | action of the color filter of 2nd Embodiment at the time of the non-lighting of a light source device. The operation | movement figure which shows the effect | action of the color filter of 2nd Embodiment at the time of lighting of a light source device. Sectional drawing which expands and shows a part of sectional structure in the subpixel of the modification of 2nd Embodiment. Sectional drawing which expands and shows a part of sectional structure in the subpixel of the modification of 2nd Embodiment.

(First embodiment)
1st Embodiment of an optical filter, a display apparatus, an image pick-up element, and the manufacturing method of an optical filter is described with reference to FIGS.

  As shown in FIG. 1, the display device includes a color filter 1 that is an example of an optical filter, and a light source device 2. The color filter 1 converts the color of light incident from the light source device 2. The light source device 2 emits light for entering the color filter 1. The light source device 2 is, for example, a liquid crystal device including a backlight, an EL device including a plurality of self-luminous elements, and an LED device including a plurality of LED (Light Emitting Diode) elements. The light source device 2 includes a plurality of unit regions arranged in a matrix, and changes the intensity of light emitted from the light source device 2 for each unit region.

  The color filter 1 includes one pixel 10 in each unit area, and each pixel 10 includes three types of sub-pixels 10A. The subpixel 10A is an example of a filter element. The type of the subpixel 10A is determined by the color of light emitted from the subpixel 10A. The three types of subpixels 10A are a red subpixel 10R, a green subpixel 10G, and a blue subpixel 10B. The red sub-pixel 10R converts the light incident on the red sub-pixel 10R into red light and emits it. The green subpixel 10G converts the light incident on the green subpixel 10G into green light and emits it. The blue subpixel 10B converts the light incident on the blue subpixel 10B into blue light and emits it.

[Sub-pixel structure]
As shown in FIG. 2, the subpixel 10A includes a plurality of isolated regions A2 and a single peripheral region A3 surrounding each isolated region A2 when viewed from the direction facing the subpixel 10A. In FIG. 2, for the convenience of explaining the isolated region A2, each isolated region A2 is shown with dots.

  The isolated regions A2 are arranged in a square array along the surface 10S of the subpixel 10A. The square array is an array in which an isolated region A2 is located at each vertex of a square LT having a structure period PT on one side. Note that the isolated regions A2 can be arranged in a hexagonal array. That is, the isolated regions A2 are arranged in an island-like array that is either a square array or a hexagonal array. The hexagonal array is an array in which an isolated region A2 is located at each vertex of an equilateral triangle.

  As shown in FIG. 3, the color filter includes a transparent support portion 11 that transmits light in the visible region. The wavelength of light in the visible region is from 400 nm to 800 nm. The cross-sectional structure of the support part 11 may be a single layer structure or a multilayer structure.

  The material which comprises the support part 11 is a dielectric material, for example, are resin, such as photocurable resin, and inorganic materials, such as quartz. It is preferable that the material which comprises the support part 11 is resin. The refractive index of the support portion 11 is higher than that of the air layer, and is preferably 1.2 or more and 1.7 or less, for example.

  The subpixel 10 </ b> A includes a first lattice layer 21, an intermediate lattice layer 31, and a second lattice layer 41 in order from the layer close to the support portion 11. The intermediate lattice layer 31 is sandwiched between the first lattice layer 21 and the second lattice layer 41. In addition, in the support part 11, the surface where the 1st lattice layer 21 is located is the surface of the support part 11, and the side where the 1st lattice layer 21 is located with respect to the support part 11 is the surface side in the structure. On the contrary, the side where the support part 11 is located with respect to the first lattice layer 21 is the back side of the structure.

[First lattice layer 21]
The first lattice layer 21 is located on the surface of the support portion 11. The first lattice layer 21 includes a plurality of first dielectric layers 22 and a single first metal layer 23. Each first dielectric layer 22 is located in the isolated region A2 when viewed from the direction facing the surface 10S of the subpixel 10A. The single first metal layer 23 is located in the peripheral region A3 when viewed from the direction facing the surface 10S. The plurality of first dielectric layers 22 are arranged in an island-like arrangement that is either a square arrangement or a hexagonal arrangement along the surface 10S.

  Each first dielectric layer 22 is a structure protruding from the surface of the support portion 11. Each first dielectric layer 22 is integral with the support portion 11, for example. Alternatively, each first dielectric layer 22 has a boundary with the surface of the support part 11, for example, and is separate from the support part 11.

  The first metal layer 23 has a mesh shape surrounding each first dielectric layer 22 one by one when viewed from the direction facing the surface 10S. In the first lattice layer 21, the single first metal layer 23 is an optical sea component through which free electrons pass, and each first dielectric layer 22 is an island component distributed in the sea component. .

  When viewed from the direction facing the surface 10S, the structural period PT, which is the period in which the first dielectric layer 22 is located, is the shortest width WP of the first dielectric layers 22 adjacent to each other and the first dielectric layer 22 This is the sum of the width WT. The structural period PT is a sub-wavelength period that is equal to or shorter than the wavelength in the visible region. In addition, the structural period PT may be 200 nm or more and 400 nm or less from the viewpoint that the color of the light emitted from the subpixel 10A becomes clear and the processing accuracy of the first lattice layer 21 is obtained. preferable.

  The ratio of the width WT of the first dielectric layer 22 to the structural period PT is not less than 0.30 and not more than 0.65. From the standpoint that the processing accuracy of the first lattice layer 21 is obtained and that plasmon resonance is likely to occur in the first lattice layer 21, the ratio of the width WT of the first dielectric layer 22 to the structural period PT is preferably 0.40 or more and 0.60 or less.

  The thickness of the first lattice layer 21 is preferably 200 nm or less. The processing accuracy of the first lattice layer 21 can be obtained, plasmon resonance is likely to occur in the first lattice layer 21, the light transmittance in the first lattice layer 21 is increased, and the color of the image by each observation is clear. From the viewpoint of becoming, the thickness of the first lattice layer 21 is preferably 15 nm or less.

[Intermediate lattice layer 31]
An intermediate lattice layer 31 is located on the first lattice layer 21. The thickness of the intermediate lattice layer 31 is thicker than the thickness of the first lattice layer 21. From the viewpoint of obtaining the processing accuracy of the intermediate lattice layer 31, the thickness of the intermediate lattice layer 31 is preferably 100 nm or more and 200 nm or less in total with the first lattice layer 21.

  The intermediate lattice layer 31 includes a plurality of first intermediate dielectric layers 32 and a single second intermediate dielectric layer 33. Each first intermediate dielectric layer 32 is located in the isolated region A2 when viewed from the direction facing the surface 10S. The single second intermediate dielectric layer 33 is located in the peripheral region A3 when viewed from the direction facing the surface 10S. The plurality of first intermediate dielectric layers 32 are arranged in an island-like arrangement that is either a square arrangement or a hexagonal arrangement along the surface 10S.

  Each first intermediate dielectric layer 32 is a structure protruding from the first dielectric layer 22. Each first intermediate dielectric layer 32 is, for example, integral with the first dielectric layer 22. Alternatively, each first intermediate dielectric layer 32 has a boundary with the first dielectric layer 22, for example, and is separate from the first dielectric layer 22. As seen from the direction facing the surface 10S, the period in which the first intermediate dielectric layer 32 is located is the sum of the shortest width WP and the width WT, like the first dielectric layer 22, and is the above-described structural period PT. . The ratio of the width WT of the first intermediate dielectric layer 32 to the structural period PT is not less than 0.30 and not more than 0.65. The ratio of the width WT of the first intermediate dielectric layer 32 to the structural period PT is preferably 0.4 or more and 0.6 or less.

  The second intermediate dielectric layer 33 has a mesh shape surrounding each of the first intermediate dielectric layers 32 when viewed from the direction facing the surface 10S. In the intermediate lattice layer 31, the single second intermediate dielectric layer 33 is structurally and optically a sea component, and each first intermediate dielectric layer 32 is structurally and optically an island component. The second intermediate dielectric layer 33 is an air layer or a resin layer.

[Second lattice layer 41]
A second lattice layer 41 is positioned on the intermediate lattice layer 31. The thickness of the second lattice layer 41 is preferably 200 nm or less, and the thickness of the second lattice layer 41 is smaller than the thickness of the intermediate lattice layer 31. The processing accuracy of the second grating layer 41 can be obtained, plasmon resonance is likely to occur in the second grating layer 41, the light transmittance in the second grating layer 41 is increased, and the color of the image by each observation is clear In view of becoming, the thickness of the second lattice layer 41 is preferably 15 nm or less.

  The second lattice layer 41 includes a plurality of second metal layers 42 and a single second dielectric layer 43. The position of each second metal layer 42 includes an isolated region A2 when viewed from the direction facing the surface 10S. The position of the single second dielectric layer 43 is included in the peripheral region A3 when viewed from the direction facing the surface 10S. The plurality of second metal layers 42 are arranged in an island-like arrangement that is either a square arrangement or a hexagonal arrangement along the surface 10S.

  Each second metal layer 42 is a structure that overlaps the top surface of the first intermediate dielectric layer 32. Each second metal layer 42 has a boundary with the first intermediate dielectric layer 32, and is separate from the first intermediate dielectric layer 32. As viewed from the direction facing the surface 10S, the period in which the second metal layer 42 is located is the sum of the shortest width WP and the width WT, as in the first dielectric layer 22, and is the structural period PT. The ratio of the width of the second metal layer 42 to the structural period PT is not less than 0.30 and not more than 0.65. The ratio of the width of the second metal layer 42 to the structural period PT is preferably 0.4 or more and 0.6 or less.

  The second dielectric layer 43 has a mesh shape that surrounds each of the second metal layers 42 when viewed from the direction facing the surface 10S. In the second lattice layer 41, the single second dielectric layer 43 is an optical sea component with fewer free electrons than the second metal layer 42, and each second metal layer 42 is a sea component. It is an island component distributed in The second dielectric layer 43 is an air layer or a resin layer.

  The volume ratio of the first metal layer 23 that is the sea component in the first lattice layer 21 is larger than the volume ratio of the second metal layer 42 that is the island component in the second lattice layer 41. The volume ratio of the second metal layer 42 that is an island component in the second lattice layer 41 is larger than the volume ratio of the metal material in the intermediate lattice layer 31.

  The structure constituted by the first dielectric layer 22 and the first intermediate dielectric layer 32 is an example of a periodic element, and the protrusion 11T protruding from the reference plane with the surface of the support portion 11 as the reference plane. But there is. The back surface of the first dielectric layer 22 is an example of one end portion of the periodic element, and the surface of the first intermediate dielectric layer 32 is an example of the other end portion of the periodic element. And the structure comprised from the support part 11, the 1st dielectric material layer 22, and the 1st intermediate | middle dielectric material layer 32 is an example of a periodic structure. Moreover, the layer comprised from the 1st metal layer 23 and the 2nd metal layer 42 is caught as a metal layer with the shape in which the shape as the whole layer follows the surface shape of a periodic structure body. The surface of the periodic structure is a surface including a region surrounding each periodic element in the reference plane and the surface of each periodic element.

  As shown in FIG. 4, in the peripheral region A3, in order from the layer close to the support portion 11, the first metal layer 23 of the first lattice layer 21, the second intermediate dielectric layer 33 of the intermediate lattice layer 31, and the first The second dielectric layer 43 of the two lattice layer 41 is located. The second intermediate dielectric layer 33 is sandwiched between the first metal layer 23 and the second dielectric layer 43.

  As described above, the cross-sectional structure of the support portion 11 may be a multilayer structure, and each first dielectric layer 22 may not have a boundary with the support portion 11. FIG. 5 shows a structure in which the support part 11 is composed of two layers, and of these layers, the layer on the surface side of the support part 11 is integrated with each first dielectric layer 22. That is, the support part 11 is provided with the base material 11a and the intermediate | middle layer 11b, and the intermediate | middle layer 11b is located in the surface side with respect to the base material 11a. Each first dielectric layer 22 protrudes from the intermediate layer 11b, and each first dielectric layer 22 and the intermediate layer 11b are integrated.

[Optical configuration of color filter]
Next, an optical configuration provided in the color filter will be described.
Here, the front surface 10S of the subpixel 10A and the back surface 10T of the subpixel 10A are in contact with the air layer, respectively, and each of the second intermediate dielectric layer 33 and the second dielectric layer 43 is an air layer. Alternatively, a configuration that is a resin layer having a refractive index close to that of an air layer will be described as an example.
As FIG. 6 shows, the refractive index of the support part 11 is a size dominated by the dielectric, and is larger than the refractive index of the air layer.

  The refractive index of the first dielectric layer 22 is higher than the refractive index of the air layer, and the refractive index of the first metal layer 23 is lower than the refractive index of the air layer. The refractive index of the first lattice layer 21 is approximated to an averaged size by the refractive index of the first metal layer 23 and the refractive index of the first dielectric layer 22. Since the ratio of the width WT of the first dielectric layer 22 to the structural period PT is not less than 0.30 and not more than 0.65, the refractive index of the first lattice layer 21 is eventually the first metal that is a sea component. The size is controlled by the layer 23 and is sufficiently lower than the refractive index of the air layer.

  The refractive index of the first intermediate dielectric layer 32 is higher than the refractive index of the air layer, and the refractive index of the second intermediate dielectric layer 33 is equal to the refractive index of the air layer or is higher than the refractive index of the air layer. high. The refractive index of the intermediate grating layer 31 is approximated to an averaged size by the refractive index of the second intermediate dielectric layer 33 and the refractive index of the first intermediate dielectric layer 32. Since the ratio of the width WT of the first intermediate dielectric layer 32 to the structural period PT is not less than 0.30 and not more than 0.65, the refractive index of the intermediate lattice layer 31 is eventually the second intermediate that is a sea component. The size is governed by the dielectric layer 33, which is higher than the refractive index of the air layer and close to the refractive index of the air layer.

  The refractive index of the second metal layer 42 is lower than the refractive index of the air layer, and the refractive index of the second dielectric layer 43 is equal to or higher than the refractive index of the air layer. The refractive index of the second lattice layer 41 is approximated to the averaged size by the refractive index of the second dielectric layer 43 and the refractive index of the second metal layer 42. Since the ratio of the width WT of the second metal layer 42 to the structural period PT is not less than 0.30 and not more than 0.65, the refractive index of the second lattice layer 41 is eventually the second dielectric that is a sea component. The size is governed by the layer 43, which is lower than the refractive index of the air layer and close to the air layer.

[Observation when not lit]
When the light source device 2 is in a non-lighting state, main light incident on the color filter is external light L1 incident from the surface side of the color filter. Here, external light L1 incident on the second lattice layer 41 from the surface 10S of the subpixel 10A enters the second lattice layer 41 from the air layer, and enters the intermediate lattice layer 31 from the second lattice layer 41. Since the external light L1 incident on the second grating layer 41 enters the second grating layer 41 having a refractive index close to that of the air layer from the air layer, and the thickness of the second metal layer 42 is sufficiently thin, Fresnel reflection is unlikely to occur at the interface between the air layer and the second lattice layer 41. Further, since the light incident on the intermediate grating layer 31 enters the intermediate grating layer 31 having a refractive index close to that of the air layer from the second grating layer 41 having a refractive index close to that of the air layer, the second grating is also used here. Fresnel reflection hardly occurs at the interface between the lattice layer 41 and the intermediate lattice layer 31.

  On the other hand, since the structural period PT of the second metal layer 42 is a sub-wavelength period equal to or smaller than the wavelength in the visible region, a part of the external light L1 incident on the second grating layer 41 is generated in the second grating layer 41. The surface plasmon is converted into surface plasmon by plasmon resonance, and the surface plasmon passes through the second lattice layer 41. The surface plasmon transmitted through the second lattice layer 41 is reconverted into light and emitted. Plasmon resonance is a phenomenon in which a part of the external light L1 incident on the second lattice layer 41 is coupled with collective vibration of electrons in the second lattice layer 41. The wavelength region of the light EP2 emitted from the second grating layer 41 due to plasmon resonance is a specific wavelength region depending on the grating structure and material including the structural period PT of the second metal layer 42. As a result, the second grating layer 41 transmits a part of the light in the wavelength region of the external light L 1 incident on the second grating layer 41 to the intermediate grating layer 31.

  Further, since the structural period PT of the first dielectric layer 22 is also a sub-wavelength period equal to or smaller than the wavelength in the visible region, a part of the light incident on the first lattice layer 21 is also plasmon in the first lattice layer 21. It is converted into surface plasmon by resonance, and the surface plasmon passes through the first lattice layer 21. The surface plasmon that has passed through the first lattice layer 21 is converted back to light and emitted. The wavelength region of the light EP1 emitted from the first grating layer 21 due to plasmon resonance is a specific wavelength region depending on the grating structure and material including the structural period PT of the first dielectric layer 22. As a result, the first grating layer 21 transmits part of the light LP1 in the wavelength region of the light incident on the first grating layer 21 to the support unit 11.

  As described above, according to the non-lighting observation in which the external light L1 is incident on the second grating layer 41 from the outside of the color filter and the surface 10S is observed from the surface side of the color filter, Fresnel reflection occurs at each of the interfaces. Difficult, generating plasmon resonance in each of the lattice layers, combined with these, black or a color close to black is visually recognized in the sub-pixel 10A.

[Observation when lighting]
As shown in FIG. 7, white light LA from the light source device 2 incident on the support unit 11 from the back surface 10 </ b> T of the subpixel 10 </ b> A enters the support unit 11 from the air layer, and enters the first lattice layer 21 from the support unit 11. enter. The light LA incident on the support unit 11 enters the first lattice layer 21 having a refractive index lower than that of the air layer from the support unit 11 having a higher refractive index than that of the air layer. Fresnel reflection is likely to occur at the interface with the lattice layer 21. However, since the thickness of the first metal layer 23 is sufficiently thin, the intensity of the reflected light LR due to Fresnel reflection is sufficiently suppressed.

  On the other hand, a part of the light transmitted through the interface between the support portion 11 and the first lattice layer 21 is consumed by plasmon resonance in the first lattice layer 21. Again, the wavelength region of the light EP1 emitted from the first grating layer 21 due to plasmon resonance is a specific wavelength region depending on the grating structure and material including the structural period PT of the first metal layer 23. As a result, the first grating layer 21 transmits light in a specific wavelength region in the light incident on the first grating layer 21 to the intermediate grating layer 31.

  In addition, part of the light transmitted through the intermediate grating layer 31 and incident on the second grating layer 41 is also consumed by plasmon resonance in the second grating layer 41. Again, the wavelength region of the light EP2 emitted from the second grating layer 41 due to plasmon resonance is a specific wavelength region depending on the grating structure and material including the structural period PT of the second dielectric layer 43. As a result, the second grating layer 41 transmits light in a specific wavelength region in the light incident on the second grating layer 41 to the air layer.

  As described above, in lighting observation in which the light LA is incident from the light source device 2 to the color filter and the surface 10S is observed from the surface side of the color filter, the colored light that has undergone plasmon resonance in each of the lattice layers, The light LP2 after color conversion corresponding to the type of the pixel 10A is visually recognized by the sub-pixel 10A.

[Color filter manufacturing method]
Next, an example of a method for manufacturing a color filter will be described.
First, the first dielectric layer 22 and the first intermediate dielectric layer 32 are formed on the surface of the support portion 11. The first dielectric layer 22 and the first intermediate dielectric layer 32 are integrally formed as a protrusion 11T protruding from the surface of the support portion 11. As a method for forming the protrusion 11T, for example, a photolithography method using light or a charged particle beam, a nanoimprint method, a plasma etching method, or the like can be adopted. In particular, as a method for forming the protrusion 11T on the surface of the support portion 11 made of resin, for example, a nanoimprint method can be used. Further, in the case where the protrusion 11T is formed by processing a hard material base material or the like, a method in which light or a photolithography method using a charged particle beam and a plasma etching method are combined may be used.

  For example, as shown in FIG. 5, when manufacturing the subpixel 10A having the support portion 11 composed of the base material 11a and the intermediate layer 11b, first, a polyethylene terephthalate sheet is used as the base material 11a. An ultraviolet curable resin is applied to the surface of 11a. Next, the surface of the synthetic quartz mold, which is an intaglio, is pressed against the surface of the coating film made of an ultraviolet curable resin, and these are irradiated with ultraviolet rays. Subsequently, the synthetic quartz mold is released from the cured ultraviolet curable resin. As a result, the unevenness of the intaglio is transferred to the resin on the surface of the base material 11a, and the protrusions 11T and the intermediate layer 11b formed of the first dielectric layer 22 and the first intermediate dielectric layer 32 are formed. Note that the ultraviolet curable resin can be changed to a thermosetting resin, and the ultraviolet irradiation can be changed to heating. Further, the ultraviolet curable resin can be changed to a thermoplastic resin, and the irradiation of the ultraviolet rays can be changed to heating and cooling.

  Next, the first metal layer 23 and the second metal layer 42 are formed on the surface of the support portion 11 including the protrusions 11T. The method for forming the first metal layer 23 and the second metal layer 42 is, for example, a vacuum evaporation method or a sputtering method. As a result, the first lattice layer 21 defined by the top surface of the first metal layer 23 is formed, and the second lattice layer 41 defined by the top surface of the second metal layer 42 is formed, and these first lattice layers are formed. An intermediate lattice layer 31 sandwiched between the first lattice layer 21 and the second lattice layer 41 is formed.

[Sub-pixel configuration example]
As shown in FIG. 8, the thinner the thickness T2 of the first metal layer 23, the greater the intensity of transmitted light in the first lattice layer 21, and the brightness of the image during lighting observation increases. The larger the ratio of the width WT of the first dielectric layer 22 to the structural period PT, the higher the lightness of the image in observation during lighting.

If the area of the first metal layer 23 is excessively small and if the area of the second metal layer 42 is excessively small, defects in the continuity of the first metal layer 23 and the continuity of the second metal layer 42 occur. As a result, it is difficult to obtain wavelength selectivity due to the above-described plasmon resonance.
In this respect, the thickness T2 of the first metal layer 23 and the thickness T4 of the second metal layer 42 are 10 minutes of the total of the thickness T2 of the first lattice layer 21 and the thickness T3 of the intermediate lattice layer 31. If the ratio of the width WT of the first dielectric layer 22 to the structural period PT is 0.30 or more, the color of the image during lighting observation can be sufficiently obtained.

  Further, the thickness T2 of the first metal layer 23 and the thickness T4 of the second metal layer 42 are 10 minutes of the total of the thickness T2 of the first lattice layer 21 and the thickness T3 of the intermediate lattice layer 31. If the ratio of the width WT of the first dielectric layer 22 to the structural period PT is 1 or less and 0.65 or less, the brightness of the image in the lighting observation can be sufficiently obtained. Furthermore, the ratio of the width WT of the first dielectric layer 22 to the structural period PT is preferably 0.6 or less, and more preferably 0.5 or less.

  The sum of the thickness T2 of the first dielectric layer 22 and the thickness T3 of the first intermediate dielectric layer 32 is the sum of the width WT of the first dielectric layer 22 and the shortest width WP. Is preferably smaller. The total of the thickness T2 of the first dielectric layer 22 and the thickness T3 of the first intermediate dielectric layer 32 is more preferably smaller than half of the structural period PT.

  With such a configuration, it is possible to increase the accuracy of the shape of the protrusion 11T in which the first dielectric layer 22 and the first intermediate dielectric layer 32 are integrated, and the protrusion 11T is a support portion. 11 is prevented from falling on the surface.

A metal material having a negative real part of the complex dielectric constant at a wavelength in the visible region tends to cause plasmon resonance in the first lattice layer 21 and the second lattice layer 41 using the metal material. Therefore, the material constituting the first metal layer 23 is a material having a negative real part of the complex dielectric constant. The material forming the second metal layer 42 is also a material having a negative real part of the complex dielectric constant.
Examples of the material constituting the first metal layer 23 and the second metal layer 42 include aluminum, silver, gold, indium, and tantalum.

  As described in the above manufacturing method, the first metal layer 23 and the second metal layer 42 are metal layers with respect to the support portion 11 having the first dielectric layer 22 and the first intermediate dielectric layer 32. The film can be formed in a single process.

  In this case, the metal particles flying from the film forming source adhere to the surface of the support portion 11 with a predetermined angular distribution. As a result, the width W4 of the second metal layer 42 is slightly larger than the width WT of the first intermediate dielectric layer 32, and the shortest width WP4 of the second metal layers 42 adjacent to each other is slightly larger than the shortest width WP. Get smaller. At this time, the ratio of the width W4 of the second metal layer 42 to the structural period PT is not less than 0.30 and not more than 0.65. Incidentally, the periphery of the first intermediate dielectric layer 32 in the first metal layer 23 is affected by the shadow effect by the second metal layer 42, and the portion closer to the first intermediate dielectric layer 32 is thinner.

  In the structure formed by the film forming method, an intermediate metal layer 32 </ b> A that is a metal layer continuous with the second metal layer 42 is also formed on the side surface of the first intermediate dielectric layer 32.

  The intermediate metal layer 32A is sandwiched between the first intermediate dielectric layer 32 and the second intermediate dielectric layer 33. The intermediate metal layer 32 </ b> A is a structure that is integral with the second metal layer 42, and the thickness on the side surface of the first intermediate dielectric layer 32 is thinner as the portion is closer to the first metal layer 23.

  In such an intermediate metal layer 32A, since the structural period PT is a sub-wavelength period, the refractive index change in the thickness direction of the second grating layer 41 and the intermediate grating layer 31 is continuous. The intermediate metal layer 32 </ b> A hardly reflects light incident on the second grating layer 41 from the surface 10 </ b> S of the subpixel 10 </ b> A and easily transmits the light to the intermediate grating layer 31 and the first grating layer 21. Therefore, in the non-lighting observation described above, a color closer to black is visually recognized by the sub-pixel 10A.

  In order to suppress Fresnel reflection particularly on the surface side of the sub-pixel 10A, it is preferable that the following conditions are satisfied. That is, the refractive index difference between the second dielectric layer 43 and the surface layer that is the layer in contact with the second dielectric layer 43 on the side opposite to the intermediate lattice layer 31 with respect to the second dielectric layer 43 is The refractive index difference between the first metal layer 23 and the support portion 11 is preferably smaller. The surface layer is, for example, an air layer. The refractive index of the second dielectric layer 43 is more preferably equal to the refractive index of the surface layer.

As described above, according to the first embodiment, the effects listed below can be obtained.
(1) According to the observation at the time of lighting in which the color filter is viewed from the direction facing the surface 10S, an image having a color other than black or white is visually recognized by the sub-pixel 10A. At this time, the color of each sub-pixel 10A is determined by the position and size of the protrusion 11T, which is each periodic element, and the metal layers 23 and 42 whose positions are determined by the protrusion 11T. Therefore, it is possible to increase the degree of freedom for adjusting the distribution of the color tone in each sub-pixel 10A, that is, the distribution of the wavelength region of the light transmitted through each sub-pixel 10A in each sub-pixel 10A.

  For example, when the color is light at the edge of the subpixel 10A, the position and size of each protrusion 11T located at the edge of the subpixel 10A, and the metal layers 23 and 42 located at the edge of the subpixel 10A. It is possible to make the thickness different from other parts of the sub-pixel 10A so that the color becomes darker.

  For example, when the color is dark at the center of the subpixel 10A, the position and size of each protrusion 11T positioned at the center of the subpixel 10A, and the metal layers 23 and 42 positioned at the center of the subpixel 10A. It is possible to make the thickness different from other parts in the sub-pixel 10A so that the color becomes thin.

  (2) Since the structural period PT is not less than 200 nm and not more than 400 nm, diffraction due to the repetition of the protrusion 11T is suppressed with respect to light in the visible region. As a result, it is possible to suppress the rainbow color from being mixed with the color of the image observed during lighting, and to make the color of the image clear for each sub-pixel 10A.

  (3) Since the sum of the thickness T2 of the first lattice layer 21 and the thickness T3 of the intermediate lattice layer 31 is not less than 100 nm and not more than 200 nm, the first lattice layer 21 and the intermediate lattice layer 31 are made visible in the visible region. Light can be transmitted sufficiently. Therefore, it is possible to further increase the vividness of color in each sub-pixel 10A and the luminance of light in each sub-pixel 10A.

  (4) Furthermore, since the thickness T2 of the first metal layer 23 and the thickness T4 of the second metal layer 42 are 15 nm or less, the vividness of the color in each subpixel 10A and the light in each subpixel 10A. It is also possible to further increase the brightness of.

  (5) Since the total of the thickness T2 of the first lattice layer 21 and the thickness T3 of the intermediate lattice layer 31 is large enough to apply an intaglio such as nanoimprint, the first dielectric layer 22 and the first dielectric layer 22 The protrusion 11T having the function of the one intermediate dielectric layer 32 can be formed as a single structure.

(6) In non-lighting observation, Fresnel reflection hardly occurs at the interface between the air layer and the second grating layer 41 or at the interface between the second grating layer 41 and the intermediate grating layer 31; Since plasmon resonance occurs in the layer 21 and the second lattice layer 41, black or a color close to black is visually recognized in the sub-pixel 10A. Therefore, it is possible to give a display suitable for non-lighting to the display device.
(7) Since the intermediate metal layer 32A has an antireflection function, the color of the image visually recognized by the non-lighting observation can be made a color closer to black.

  (8) A manufacturing method using the nanoimprint method for forming the protrusion 11T, that is, by transferring the unevenness of the intaglio to the resin coated on the surface of the substrate 11a, the support 11 and the plurality of protrusions 11T If it is a manufacturing method which forms the periodic structure comprised from, the periodic structure which has fine unevenness | corrugation can be formed easily and suitably.

  For example, it is possible to form a lattice structure in which plasmon resonance occurs by forming a plurality of holes arranged in a sub-wavelength period in a flat metal layer and filling the holes with a dielectric. However, in order to form minute holes in the metal layer, it is necessary to form an etching mask using a photolithography method or a nanoimprint method, and to etch the metal layer by a plasma etching method. Becomes complicated. As a result, the yield of the color filter tends to decrease. On the other hand, a yield reduction can be suppressed by a method of forming a lattice structure in which plasmon resonance occurs by laminating a metal layer on the unevenness formed using the nanoimprint method as in this embodiment.

<Modification of First Embodiment>
The first embodiment can be implemented with the following modifications.
[Intermediate lattice layer 31]
The first intermediate dielectric layer 32 and the second intermediate dielectric layer 33 can be embodied as separate structures. At this time, the second intermediate dielectric layer 33 is preferably a resin layer having a refractive index closer to the refractive index of the air layer than the refractive index of the first intermediate dielectric layer 32.

  The second intermediate dielectric layer 33 and the second dielectric layer 43 can be embodied as separate structures. At this time, the second intermediate dielectric layer 33 is preferably a resin layer having a refractive index closer to the refractive index of the air layer than the refractive index of the second dielectric layer 43.

[First lattice layer 21]
As shown in FIG. 9, the shape of the protrusion 11 </ b> T composed of the first dielectric layer 22 and the first intermediate dielectric layer 32 can be embodied as a cone protruding from the surface of the support portion 11. With such a structure, it is possible to smoothly release the intaglio for forming the first dielectric layer 22 and the first intermediate dielectric layer 32 when forming the first dielectric layer 22 and the first intermediate dielectric layer 32.

[Periodic element]
The periodic elements arranged on the reference surface can be embodied as a bottomed hole provided on the surface of the support portion 11. At this time, the reference surface is the surface of the support portion 11. One end of the periodic element is an opening provided in each hole, and the other end of the periodic element is a bottom surface provided in each hole. And the 1st metal layer 23 is located in the mesh shape surrounding the opening part of each hole, and the 2nd metal layer 42 is located in the bottom face of each hole. The interior of each hole is partitioned into a second metal layer 42 and a first intermediate dielectric layer 32 located above the second metal layer 42. The space surrounded by the first metal layer 23 functions as the first dielectric layer 22. Even with such a configuration, it is possible to obtain the effects according to the above (1) to (4) and (6) to (8).

[Protective layer]
The color filter further includes a protective layer on the second metal layer 42. At this time, the intensity of Fresnel reflection at the interface between the protective layer and the second metal layer 42 and the wavelength selectivity in the color filter associated therewith vary depending on the refractive index of the protective layer. Therefore, the material constituting the protective layer is appropriately selected based on the wavelength region selected by the color filter.

  As shown in FIG. 10, the protective layer 45 can be embodied as a structure integrated with the second dielectric layer 43 and the second intermediate dielectric layer 33. At this time, the protective layer 45 is preferably a low refractive index resin layer. The low refractive index resin layer has a refractive index closer to the refractive index of the air layer than the refractive index of the first dielectric layer 22 and the refractive index of the first intermediate dielectric layer 32.

[Other forms]
The arrangement of the isolated regions A2 viewed from the direction facing the surface 10S of the subpixel 10A is not limited to a square array and a hexagonal array, and may be a two-dimensional lattice array. That is, the plurality of first dielectric layers 22 may be arranged in a two-dimensional lattice, the plurality of first intermediate dielectric layers 32 may be arranged in a two-dimensional lattice, and the plurality of first dielectric layers 22 may be arranged. The two metal layers 42 need only be arranged in a two-dimensional lattice. In other words, the periodic elements of the periodic structure need only be arranged in a two-dimensional lattice shape having a sub-wavelength period. The two-dimensional lattice-like arrangement is an arrangement in which elements are arranged along each of two directions intersecting in a two-dimensional plane. At this time, the ratio of the width WT to the structural period PT is the ratio of the width WT to the structural period PT in one direction, and that the ratio is within a predetermined range means that the two elements in which the periodic elements are arranged Each indicates that the ratio of the width WT to the structural period PT is within a predetermined range. The thickness of each layer included in the color filter is within a predetermined range with respect to the structural period PT. The thickness of each layer is predetermined with respect to the structural period PT in each of the two directions in which the periodic elements are arranged. It is within the range of.

  Further, the shape of the isolated region A2 viewed from the direction facing the surface 10S of the subpixel 10A, that is, the planar shape of the periodic element is not limited to a square, but may be a rectangle or other polygons, There may be.

  -The structure of the optical filter of 1st Embodiment may be applied to the filter used for an image pick-up element. The imaging element is, for example, a CCD (Charge Coupled Device) type or a CMOS (Complementary Metal Oxide Semiconductor) type image sensor. As shown in FIG. 11, the imaging element 140 includes an optical filter 120 having a plurality of filter elements 121 and a light receiving element group 130 having a plurality of light receiving elements 131. The filter element 121 has a stacked structure similar to that of the sub-pixel 10A of the first embodiment, that is, a structure composed of a periodic structure and a metal layer, and has a specific wavelength region of light incident on the filter element 121. Transmits light. The light receiving element 131 is an element that converts light incident on the light receiving element 131 into electric charges.

  The optical filter 120 and the light receiving element group 130 face each other, and are arranged so that light transmitted through one filter element 121 enters one light receiving element 131. In other words, a portion of the optical filter 120 that emits transmitted light to one light receiving element 131 is one filter element 121. The light receiving element 131 receives the light transmitted through the filter element 121 and converts it into an electrical signal. The electrical signal from the light receiving element 131 is received by the signal processing circuit, and is received by the optical filter 120. An image of an article or the like located on the side opposite to the element group 130 is recorded.

  The optical filter 120 is, for example, an on-chip color filter, and the plurality of filter elements 121 include a plurality of types of filter elements 121 having different transmission wavelength regions. For example, the plurality of filter elements 121 include three types of filter elements 121: a filter element 121 that transmits red light, a filter element 121 that transmits green light, and a filter element 121 that transmits blue light. included. Alternatively, the plurality of filter elements 121 include a filter element 121 that transmits yellow (yellow) light, a filter element 121 that transmits light of cyan (cyan), and a filter element that transmits magenta light. Four types of filter elements 121, 121 and a filter element 121 that transmits green light, are included.

  Alternatively, when the image sensor 140 is an image sensor that is used for recording an image in one color, such as an image sensor used in an infrared camera, the wavelength region that each of the plurality of filter elements 121 transmits is as follows. It may match.

  The structural period PT of the periodic element of the periodic structure provided in the filter element 121 may be equal to or smaller than the wavelength region that the filter element 121 transmits. That is, in the first embodiment and the second embodiment, the sub-wavelength period is defined as a period equal to or less than the wavelength region that the filter element 121 transmits.

  The wavelength region of light transmitted through the filter element 121 is adjusted by a plurality of factors such as the structural period PT, the width WT of the periodic element, the distance between one end and the other end of the periodic element, and the film thickness of the metal layers 23 and 42. Is possible. Therefore, regardless of the device in which the optical filter 120 is used, the degree of freedom for adjusting the distribution of the wavelength region of light transmitted through the filter element 121 within the filter element 121 can be increased.

(Second Embodiment)
A second embodiment of the optical filter, the display device, the image sensor, and the method for manufacturing the optical filter will be described with reference to FIGS. The second embodiment is also a form in which the optical filter is embodied as a color filter provided in the display device. Below, it demonstrates centering around the difference between 2nd Embodiment and 1st Embodiment, about the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

[Sub-pixel structure]
As shown in FIG. 12, the subpixel 10 </ b> A includes an upper lattice layer 51 in addition to the support portion 11, the first lattice layer 21, the intermediate lattice layer 31, and the second lattice layer 41. The first lattice layer 21, the intermediate lattice layer 31, the second lattice layer 41, and the upper lattice layer 51 are arranged in this order from the surface of the support portion 11. That is, the second lattice layer 41 is sandwiched between the intermediate lattice layer 31 and the upper lattice layer 51.

  The support part 11 has the same configuration as in the first embodiment. FIG. 12 shows a form in which the support portion 11 is composed of a base material 11a and an intermediate layer 11b. In addition, when the support part 11 is comprised from the base material 11a and the intermediate | middle layer 11b, it is so preferable that the refractive index of the material which comprises the base material 11a and the refractive index of the material which comprises the intermediate | middle layer 11b are near. Each of the base material 11a and the intermediate layer 11b has a refractive index higher than that of the air layer, for example, not less than 1.2 and not more than 1.7.

[First lattice layer 21]
The first lattice layer 21 has the same configuration as that of the first embodiment, and each includes a plurality of first dielectric layers 22 located in the isolated region A2 and a single first metal layer located in the peripheral region A3. 23. The ratio of the width WT of the first dielectric layer 22 to the structural period PT is 0.30 or more and 0.65 or less, preferably 0.40 or more and 0.60 or less. Furthermore, the ratio is preferably 0.5 or less. Further, the thickness of the first lattice layer 21 is preferably 200 nm or less, and particularly preferably 15 nm or less.

[Intermediate lattice layer 31]
The intermediate lattice layer 31 includes a plurality of first intermediate dielectric layers 32 each located in the isolated region A2, and a single second intermediate dielectric layer 34 located in the peripheral region A3. The intermediate lattice layer 31 has the same configuration as that of the first embodiment except that the material of the second intermediate dielectric layer 34 is different from that of the second intermediate dielectric layer 33 of the first embodiment.

  That is, the thickness of the intermediate lattice layer 31 is thicker than the thickness of the first lattice layer 21, and the total thickness of the first lattice layer 21 and the intermediate lattice layer 31 is preferably 100 nm or more and 200 nm or less. The ratio of the width WT of the first intermediate dielectric layer 32 to the structural period PT is not less than 0.30 and not more than 0.65, and preferably not less than 0.4 and not more than 0.6. Furthermore, the ratio is preferably 0.5 or less.

[Second lattice layer 41]
The second lattice layer 41 includes a plurality of second metal layers 42 each positioned in a region including the isolated region A2, and a single second dielectric layer 44 included in the peripheral region A3. The second lattice layer 41 has the same configuration as that of the first embodiment, except that the material of the second dielectric layer 44 is different from that of the second dielectric layer 43 of the first embodiment.

  The thickness of the second lattice layer 41 is thinner than the thickness of the intermediate lattice layer 31. The thickness of the second lattice layer 41 is preferably 200 nm or less, and particularly preferably 15 nm or less. The ratio of the width of the second metal layer 42 to the structural period PT is 0.30 or more and 0.65 or less, and preferably 0.4 or more and 0.6 or less. Furthermore, the ratio is preferably 0.5 or less.

[Upper lattice layer 51]
The upper lattice layer 51 includes a plurality of first upper dielectric layers 52 and a single second upper dielectric layer 53. The position of each first upper dielectric layer 52 includes an isolated region A2 when viewed from the direction facing the surface 10S. The position of the single second upper dielectric layer 53 is included in the peripheral region A3 when viewed from the direction facing the surface 10S. The thickness of the upper lattice layer 51 is preferably 200 nm or less.

  Each first upper dielectric layer 52 is a structure that overlaps the top surface of the second metal layer 42. Each first upper dielectric layer 52 is separate from the second metal layer 42. When viewed from the direction facing the surface 10S, the period in which the first upper dielectric layer 52 is located is the structural period PT. The ratio of the width of the first upper dielectric layer 52 to the structural period PT is 0.30 or more and 0.65 or less, and preferably 0.4 or more and 0.6 or less. Furthermore, the ratio is preferably 0.5 or less.

  The second upper dielectric layer 53 has a mesh shape surrounding each first upper dielectric layer 52 as viewed from the direction facing the surface 10S. The second upper dielectric layer 53 is separate from the second dielectric layer 44. In the upper lattice layer 51, the second upper dielectric layer 53 is structurally and optically a sea component, and each first upper dielectric layer 52 is structurally and optically an island component.

  As shown in FIG. 13, in the peripheral region A3, in order from the layer close to the support portion 11, the first metal layer 23 of the first lattice layer 21, the second intermediate dielectric layer 34 of the intermediate lattice layer 31, The second dielectric layer 44 of the two lattice layer 41 and the second upper dielectric layer 53 of the upper lattice layer 51 are located.

[Material of each lattice layer]
The first dielectric layer 22 and the first intermediate dielectric layer 32 are dielectrics, and are made of, for example, a resin such as a photocurable resin or an inorganic material such as quartz, as in the first embodiment. The refractive index of each of the first dielectric layer 22 and the first intermediate dielectric layer 32 is higher than that of the air layer, for example, not less than 1.2 and not more than 1.7. For example, the intermediate layer 11b, the first dielectric layer 22, and the first intermediate dielectric layer 32 of the base material 11a are an integral structure, and are composed of the same material.

  The first metal layer 23 and the second metal layer 42 are made of a metal material. The material constituting the first metal layer 23 and the second metal layer 42 is a material in which the real part of the complex dielectric constant in the visible region wavelength is a negative value, as in the first embodiment. For example, aluminum, silver, Gold, indium, tantalum and the like are preferable. The first metal layer 23 and the second metal layer 42 are made of the same material, for example.

The second intermediate dielectric layer 34, the second dielectric layer 44, and the first upper dielectric layer 52 are transparent dielectrics that transmit light in the visible region. The second intermediate dielectric layer 34, the second dielectric layer 44, and the first upper dielectric layer 52 are composed of silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), and tantalum oxide (Ta ₂ O ₅ ). , Niobium oxide (Nb ₂ O ₅ ), zirconium dioxide (ZrO ₂ ), titanium dioxide (TiO ₂ ), magnesium fluoride (MgF ₂ ), and calcium fluoride (CaF ₂ ). . Among these, the materials constituting the second intermediate dielectric layer 34, the second dielectric layer 44, and the first upper dielectric layer 52 are made of titanium, niobium, aluminum, tantalum, hafnium, zirconium, silicon, and magnesium. It is preferable to include an oxide of any one material selected from the group.

  However, the second intermediate dielectric layer 34, the second dielectric layer 44, and the first upper dielectric layer 52 may be made of an organic compound. The refractive index of each of the second intermediate dielectric layer 34, the second dielectric layer 44, and the first upper dielectric layer 52 is higher than that of the air layer, for example, 1.3 or more and 3.0 or less.

  For example, the second intermediate dielectric layer 34 and the second dielectric layer 44 are an integral structure, and the second intermediate dielectric layer 34, the second dielectric layer 44, and the first upper dielectric layer 52 are , Composed of the same material.

  The second upper dielectric layer 53 is a transparent dielectric that transmits light in the visible region, and is an air layer or a resin layer having a refractive index close to that of the air layer. The refractive index of the second upper dielectric layer 53 is lower than the refractive index of each of the first upper dielectric layer 52 and the second dielectric layer 44.

  In the above configuration, the structure configured by the first dielectric layer 22 and the first intermediate dielectric layer 32 is an example of a periodic element, and the protrusion protruding from the reference plane with the surface of the support portion 11 as the reference plane. It is also part 11T. And the structure comprised from the support part 11, the 1st dielectric material layer 22, and the 1st intermediate | middle dielectric material layer 32 is an example of a periodic structure. Further, the layer composed of the first metal layer 23 and the second metal layer 42 is located on the surface of the periodic structure, and the shape of the entire layer follows the surface shape of the periodic structure. Captured as layer 61. Further, the layer composed of the second intermediate dielectric layer 34, the second dielectric layer 44, and the first upper dielectric layer 52 is on the surface opposite to the surface in contact with the periodic structure in the metal layer 61. The dielectric layer 62 is positioned so that the shape of the entire layer follows the surface shape of the metal layer 61.

  At this time, in order to realize the configuration of each of the lattice layers 21, 31, 41, 51 described above, the thickness T5 that is the height of the protrusion 11T is preferably 100 nm or more and 200 nm or less. Moreover, the thickness T6 of the metal layer 61 is preferably 200 nm or less, and particularly preferably 15 nm or less. And the thickness T7 of the dielectric material layer 62 is below the thickness T5 which is the height of the protrusion 11T, and it is preferable that it is 200 nm or less. When the dielectric layer 62 located in the region between the adjacent protrusions 11T is recessed from the metal layer 61 on the protrusions 11T, a part of the second dielectric layer 44 of the second lattice layer 41 or All are made of the same material as the second upper dielectric layer 53 of the upper lattice layer 51. That is, in this case, part or all of the second dielectric layer 44 is an air layer or a resin layer. However, the second dielectric layer 44 is preferably a structure continuous from the second intermediate dielectric layer 34 as described above.

  Furthermore, as in the first embodiment, the thickness T6 of the metal layer 61 is preferably 1/10 or less of the thickness T5 that is the height of the protrusion 11T. The thickness T5, which is the height of the protrusion 11T, is preferably smaller than the structural period PT, and more preferably smaller than half the structural period PT.

  Note that, depending on the manufacturing method of the metal layer 61, the thickness of the metal layer 61 is such that the region on the protrusion 11T, that is, the second metal layer 42, and the region between the adjacent protrusions 11T, that is, the first metal layer 23, May vary. In the present embodiment, the thickness T6 of the metal layer 61 refers to a band-shaped region in the peripheral region A3, that is, the metal layer 61 located at the center in the width direction of the region where the protrusion 11T does not exist along one direction. Is defined as the thickness of The same applies to the first embodiment.

  Similarly, depending on the manufacturing method of the dielectric layer 62, the thickness of the dielectric layer 62 may be a region on the protrusion 11T, that is, a region between the first upper dielectric layer 52 and the adjacent protrusion 11T, that is, the first. The two intermediate dielectric layers 34 and the second dielectric layer 44 may be different. In the present embodiment, the thickness T7 of the dielectric layer 62 refers to a dielectric located in the central portion in the width direction of a region extending in a band shape in the peripheral region A3, that is, a region where the protrusion 11T does not exist along one direction. Defined as the thickness of layer 62. The same applies to the first embodiment.

[Color filter manufacturing method]
Next, an example of a method for manufacturing the color filter of the second embodiment will be described.
The support portion 11, the first dielectric layer 22, the first intermediate dielectric layer 32, the first metal layer 23, and the second metal layer 42 are formed in the same manner as in the first embodiment. That is, the first dielectric layer 22 and the first intermediate dielectric layer 32 are integrally formed as a protrusion 11T protruding from the surface of the support portion 11. For the formation of the protrusion 11T, for example, a photolithography method using light or a charged particle beam, a nanoimprint method, a plasma etching method, or the like can be employed. In particular, as a method for forming the protrusion 11T on the surface of the support portion 11 made of resin, for example, a nanoimprint method can be used. Further, in the case where the protrusion 11T is formed by processing a hard material base material or the like, a method in which light or a photolithography method using a charged particle beam and a plasma etching method are combined may be used.

  Next, the metal layer 61 is formed on the surface of the support portion 11 on which the protrusions 11T are formed using a vacuum deposition method, a sputtering method, or the like. The metal layer 61 is formed in a shape that follows the surface shape of the periodic structure including the support portion 11 and the protrusion 11T. Thereby, the first metal layer 23 and the second metal layer 42 are formed.

  Next, a dielectric layer 62 is formed on the surface of the structure on which the metal layer 61 is formed. For example, a vacuum deposition method or a sputtering method is used to form the dielectric layer 62. The dielectric layer 62 is formed in a shape that follows the surface shape of the metal layer 61. Thus, the second intermediate dielectric layer 34, the second dielectric layer 44, and the first upper dielectric layer 52 are formed.

  By such a manufacturing method, the first lattice layer 21 defined by the top surface of the first metal layer 23 is formed, and the top surface of the first intermediate dielectric layer 32, that is, the middle defined by the top surface of the protrusion 11T. A lattice layer 31 is defined. Further, the second lattice layer 41 defined by the top surface of the second metal layer 42 is formed, and the upper lattice layer 51 defined by the top surface of the first upper dielectric layer 52 is formed.

[Optical action of color filter]
With reference to FIG. 14 and FIG. 15, the optical configuration and operation of the color filter of the second embodiment will be described.
As shown in FIG. 14, when the light source device 2 is in a non-lighting state, external light L1 incident from the surface side of the color filter enters the upper lattice layer 51 from the air layer. The refractive index of the upper grating layer 51 is approximated to a size averaged by the refractive index of the first upper dielectric layer 52 and the refractive index of the second upper dielectric layer 53. That is, the refractive index of the upper lattice layer 51 is a size controlled by the second upper dielectric layer 53, which is a sea component, and a value close to that of the air layer. At this time, since the external light L1 enters the upper lattice layer 51 having a refractive index close to that of the air layer from the air layer, Fresnel reflection hardly occurs at the interface between the air layer and the upper lattice layer 51. Therefore, reflection at the interface between the air layer and the upper lattice layer 51 is suppressed, and light incident on the upper lattice layer 51 passes through the upper lattice layer 51 and reaches the second lattice layer 41.

  The refractive index of the second grating layer 41 is approximated to a size averaged by the refractive index of the second metal layer 42 and the refractive index of the second dielectric layer 44. That is, the refractive index of the second lattice layer 41 is a size controlled by the second dielectric layer 44, which is a sea component, and is higher than the refractive index of the air layer. Further, since the second lattice layer 41 has a lattice structure composed of a metal and a dielectric, and the structural period PT of the second metal layer 42 is a sub-wavelength period, plasmon resonance occurs in the second lattice layer 41. Therefore, a part of the light reaching the second grating layer 41 is reflected at the interface between the upper grating layer 51 and the second grating layer 41, and a part of the light reaching the second grating layer 41 is reflected on the surface plasmon. It is converted and passes through the second lattice layer 41. Light EP2 in the wavelength region consumed by plasmon resonance is not reflected at the interface between the upper grating layer 51 and the second grating layer 41.

  The refractive index of the intermediate grating layer 31 is approximated to a size averaged by the refractive index of the first intermediate dielectric layer 32 and the refractive index of the second intermediate dielectric layer 34. That is, the refractive index of the intermediate lattice layer 31 is a size controlled by the second intermediate dielectric layer 34 that is a sea component. Since the first intermediate dielectric layer 32 and the second intermediate dielectric layer 34 are transparent dielectric materials that transmit light in the visible region, the intermediate lattice layer 31 has high light transmittance in the visible region. Depending on the difference between the refractive index of the second grating layer 41 and the refractive index of the intermediate grating layer 31, a part of the light reaching the intermediate grating layer 31 is reflected at the interface between the second grating layer 41 and the intermediate grating layer 31. To do.

  The refractive index of the first lattice layer 21 is approximated to a size averaged by the refractive index of the first dielectric layer 22 and the refractive index of the first metal layer 23. That is, the refractive index of the first lattice layer 21 is controlled by the first metal layer 23 that is a sea component. In addition, the first lattice layer 21 has a lattice structure made of a metal and a dielectric, and the structural period PT of the first dielectric layer 22 is a sub-wavelength period. Therefore, plasmon resonance occurs in the first lattice layer 21. Therefore, a part of the light reaching the first lattice layer 21 is reflected at the interface between the intermediate lattice layer 31 and the first lattice layer 21, and a part of the light reaching the first lattice layer 21 is reflected on the surface plasmon. It is converted and passes through the first lattice layer 21. The light EP 1 in the wavelength region consumed by plasmon resonance is not reflected at the interface between the intermediate grating layer 31 and the first grating layer 21.

  A part of the light transmitted through the first grating layer 21 is at the interface between the first grating layer 21 and the support part 11, the interface between the intermediate layer 11b and the substrate 11a, or the interface between the support part 11 and the air layer. Can be reflected. Then, a part of the light LP1 in the wavelength region of the light transmitted through the first grating layer 21 passes through the support portion 11 and is emitted to the back surface side of the color filter.

  The light reflected at the interface of each layer is emitted to the surface side of the color filter and causes interference due to the optical path difference between these lights. As a result, when external light L1 is incident from the outside of the color filter, light LR1 in a specific wavelength region in which plasmon resonance and light interference act is emitted on the surface side of the color filter. However, since the first metal layer 23 and the second metal layer 42 are sufficiently thin, the intensity of the light LR1 that is the reflected light can be suppressed. As a result, according to the non-lighting observation in which the external light L1 is incident on the upper lattice layer 51 from the outside of the color filter and the surface 10S is observed from the surface side of the color filter, the color is different from black and white. In addition, a dark color is visually recognized by the sub-pixel 10A.

  As shown in FIG. 15, when white light LA is incident from the light source device 2 to the back surface 10 </ b> T of the sub-pixel 10 </ b> A, similarly, plasmon resonance occurs in each of the first grating layer 21 and the second grating layer 41. On the surface side of the color filter, a specific wavelength region including light obtained by reconverting the surface plasmons transmitted through each of the first grating layer 21 and the second grating layer 41 and light transmitted through all the layers. Light LP2 is emitted. Accordingly, in lighting observation in which the light LA is incident from the light source device 2 to the color filter and the surface 10S is observed from the surface side of the color filter, the light LP2 after color conversion corresponding to the type of the sub-pixel 10A, that is, black And a colored color different from white is visually recognized by the sub-pixel 10A.

  On the other hand, when the white light LA is incident on the back surface 10T of the sub-pixel 10A from the light source device 2, light reflected from the interface of each layer is reflected on the back surface side of the color filter, in addition to Fresnel reflection, The light LR2 in a specific wavelength region where the interference acts is emitted, but the intensity of the light LR2 is kept low.

  As described above, since plasmon resonance occurs with respect to light in a specific wavelength region in each of the first grating layer 21 and the second grating layer 41, each of the grating layers 21 and 41 is consumed by plasmon resonance. The wavelength region transmitted through the layers 21 and 41 is different from the wavelength region that is not consumed by plasmon resonance and is reflected at the interface between the lattice layers 21 and 41 and other layers. Therefore, the wavelength regions of the light beams LR1 and LR2 that are reflected light and the light beams LP1 and LP2 that are transmitted light are different from each other.

  Further, since the ratio of the width WT to the structural period PT is not less than 0.30 and not more than 0.65, the first lattice layer 21 of the first lattice layer 21 and the second lattice layer 41 in which plasmon resonance occurs is the first lattice layer 21. The metal layer 23 is a dominant layer, and the second lattice layer 41 is a layer where the second dielectric layer 44 is dominant. Due to the difference in structure, the wavelength region consumed by plasmon resonance is different between the first lattice layer 21 and the second lattice layer 41, and the interface between the first lattice layer 21 and the other layers, The light reflectance is different at the interface between the second lattice layer 41 and other layers. The light incident on the sub-pixel 10 </ b> A from the surface side of the color filter reaches the second grating layer 41 earlier than the first grating layer 21, and receives a large optical action by the second grating layer 41. On the other hand, the light incident on the sub-pixel 10 </ b> A from the back side of the color filter reaches the first grating layer 21 earlier than the second grating layer 41 and is greatly subjected to the optical action by the first grating layer 21. As a result, the color of reflected light is particularly different between when light enters the subpixel 10A from the front side and when light enters the subpixel 10A from the back side.

  Furthermore, the wavelength region consumed by plasmon resonance in each of the lattice layers 21 and 41 is the lattice structure of each of the lattice layers 21 and 41, that is, the structural period PT, the thickness of each of the lattice layers 21 and 41, and the first dielectric layer 22. And the width WT of the second metal layer 42, and also depends on the material of each of the lattice layers 21 and 41, that is, the refractive index of the material of the metal layer 61, the material of the protrusion 11 </ b> T, and the material of the dielectric layer 62. change. Therefore, for example, the wavelength region of reflected light or transmitted light is adjusted by selecting the material of the first dielectric layer 22 in the first lattice layer 21 or selecting the material of the second dielectric layer 44 in the second lattice layer 41. can do. That is, the color of light after conversion by the sub-pixel 10A can be adjusted.

  For example, in the two subpixels 10A having the same structural period PT, the materials of the protrusion 11T and the metal layer 61 are the same in the two subpixels 10A, and the material of the dielectric layer 62 is the two subpixels 10A. Different sub-pixels 10A are compared in the pixel 10A. That is, in the two subpixels 10A, the configuration of the first lattice layer 21 is the same, the material of the first intermediate dielectric layer 32 in the intermediate lattice layer 31 is also the same, and the second metal layer in the second lattice layer 41 is the same. The material of 42 is also the same. On the other hand, in the two subpixels 10A, the materials of the second intermediate dielectric layer 34 in the intermediate lattice layer 31 are different from each other, the materials of the second dielectric layer 44 in the second lattice layer 41 are different from each other, and in the upper lattice layer 51 The materials of the first upper dielectric layer 52 are also different from each other. Thus, in each of the two subpixels 10A, the configurations of the intermediate lattice layer 31, the second lattice layer 41, and the upper lattice layer 51 are different from each other, so that the wavelength region of light transmitted through these layers is different. Are different from each other in the two sub-pixels 10A. Therefore, the wavelength regions of the light after color conversion emitted from the two subpixels 10A are different from each other.

As described above, according to the second embodiment, in addition to the effects (1) to (5) and (8) of the first embodiment, the effects listed below can be obtained.
(9) Since the sub-pixel 10 </ b> A includes the dielectric layer 62, the wavelength region that the sub-pixel 10 </ b> A transmits can be adjusted by changing the material constituting the dielectric layer 62. Therefore, the degree of freedom for adjusting the distribution of the wavelength region of the light transmitted through the subpixel 10A within the subpixel 10A is further increased.

  (10) If the dielectric layer 62 is formed of a material including an oxide of any one material selected from the group consisting of titanium, niobium, aluminum, tantalum, hafnium, zirconium, silicon, and magnesium The refractive index of the dielectric layer 62 can be selected from a wide range. Therefore, the degree of freedom of adjustment of the wavelength region through which the subpixel 10A is transmitted is increased.

  (11) If the thickness T7 of the dielectric layer 62 is equal to or less than the thickness T5, which is the height of the protrusion 11T, the light transmission in the subpixel 10A is improved, so that the transmission of the subpixel 10A is achieved. The intensity of light is increased. Accordingly, it is possible to increase the vividness of the color in each sub-pixel 10A and the luminance of light in each sub-pixel 10A. Further, if the thickness T7 of the dielectric layer 62 is 200 nm or less, the light transmittance in the sub-pixel 10A is sufficiently enhanced.

<Modification of Second Embodiment>
The second embodiment can be implemented with the following modifications.
The area ratio occupied by the isolated area A2 in the plane composed of the isolated area A2 and the peripheral area A3, that is, the ratio of the area occupied by the protrusion 11T per unit area in the plane including the reference surface and the protrusion 11T is: Preferably it is greater than 0.1. If the area ratio is greater than 0.1, the aspect ratio, which is the ratio of the height to the width of the protrusion 11T, can be prevented from becoming excessively large. Therefore, the structure including the support portion 11 and the protrusion 11T. The durability of the body is improved, and the processing accuracy of the protrusion 11T is easily obtained.

  On the other hand, if the area ratio is smaller than 0.5, occurrence of Fresnel reflection at the interface between the upper lattice layer 51 and its upper layer is preferably suppressed. Note that, depending on the manufacturing method of the metal layer 61 and the dielectric layer 62, the material also adheres to the side surface of the protrusion 11T when these layers are formed. If the area ratio is smaller than 0.5, the size of the region between the adjacent protrusions 11T is sufficiently secured, and the region between the protrusions 11T forms the metal layer 61 and the dielectric layer 62. In this case, it is possible to prevent the material from adhering to the side surface of the protrusion 11T from being buried. Therefore, the metal layer 61 and the dielectric layer 62 are easily formed in a shape that follows the surface shape of the lower layer. As a result, the upper lattice layer 51 interspersed with the first upper dielectric layer 52 is preferably formed, and the effect of suppressing Fresnel reflection at the interface of the upper lattice layer 51 is preferably obtained.

  In order to suppress Fresnel reflection particularly on the surface side of the sub-pixel 10A, a surface layer that is a layer in contact with the second upper dielectric layer 53 on the side opposite to the second grating layer 41 with respect to the second upper dielectric layer 53. The refractive index difference between the first upper dielectric layer 53 and the second upper dielectric layer 53 is preferably smaller than the refractive index difference between the first metal layer 23 and the support portion 11. The surface layer is, for example, an air layer. The refractive index of the second upper dielectric layer 53 is more preferably equal to the refractive index of the surface layer.

In the second embodiment, as in the first embodiment, the first metal layer 23 and the second metal layer 42 may have the shape characteristics shown in FIG. The metal layer 61 may include an intermediate metal layer 32 </ b> A that is a metal layer located on the side surface of the first intermediate dielectric layer 32 and continuing to the second metal layer 42. The intermediate metal layer 32 </ b> A is sandwiched between the first intermediate dielectric layer 32 and the second intermediate dielectric layer 34, and the thickness on the side surface of the first intermediate dielectric layer 32 is close to the first metal layer 23. It is so thin. Note that plasmon resonance can also occur in the intermediate lattice layer 31 due to the presence of the intermediate metal layer 32A.
In the second embodiment, similarly to the structure shown in FIG. 9 of the first embodiment, the shape of the protrusion 11T may be a cone shape protruding from the surface of the support portion 11.

  As shown in FIG. 16, the color filter may further include a protective layer 45 on the dielectric layer 62. According to such a configuration, it is possible to protect the structure including the support portion 11 and the protrusion 11T, the metal layer 61, and the dielectric layer 62. The protective layer 45 can be embodied in a structure that is integral with the second upper dielectric layer 53. At this time, the protective layer 45 is preferably a low refractive index resin layer. The low refractive index resin layer has a refractive index closer to the refractive index of the air layer than the refractive index of the first dielectric layer 22 and the refractive index of the first intermediate dielectric layer 32.

Further, if the protective layer 45 constituting the surface of the color filter is made of a resin containing fluorine, it is possible to prevent dirt from adhering to the surface of the color filter.
The protective layer 45 may have a flat surface as shown in FIG. 16, or may have a shape that follows the surface shape of the dielectric layer 62.

  The arrangement of the isolated regions A2 viewed from the direction facing the surface 10S of the subpixel 10A is not limited to a square array and a hexagonal array, and may be a two-dimensional lattice shape. That is, the plurality of first dielectric layers 22 may be arranged in a two-dimensional lattice, the plurality of first intermediate dielectric layers 32 may be arranged in a two-dimensional lattice, and the plurality of first dielectric layers 22 may be arranged. The two metal layers 42 need only be arranged in a two-dimensional lattice, and the plurality of first upper dielectric layers 52 need only be arranged in a two-dimensional lattice. In other words, the periodic elements of the periodic structure need only be arranged in a two-dimensional lattice shape having a sub-wavelength period. The two-dimensional lattice-like arrangement is an arrangement in which elements are arranged along each of two directions intersecting in a two-dimensional plane. At this time, the ratio of the width WT to the structural period PT is the ratio of the width WT to the structural period PT in one direction, and that the ratio is within a predetermined range means that the two elements in which the periodic elements are arranged Each indicates that the ratio of the width WT to the structural period PT is within a predetermined range. The thickness of each layer included in the color filter is within a predetermined range with respect to the structural period PT. The thickness of each layer is predetermined with respect to the structural period PT in each of the two directions in which the periodic elements are arranged. It is within the range of.

  Further, the shape of the isolated region A2 viewed from the direction facing the surface 10S of the subpixel 10A, that is, the planar shape of the periodic element is not limited to a square, but may be a rectangle or other polygons, There may be.

  -Also in 2nd Embodiment, the bottomed hole with which the periodic element arranged in a reference plane is equipped with the surface of the support part 11 may be sufficient. Specifically, as illustrated in FIG. 17, a recessed portion 11 </ b> H that is a hole recessed from the surface of the support portion 11 is located in the isolated region A <b> 2. When viewed from the direction facing the surface 10S of the sub-pixel 10A, the plurality of recesses 11H are arranged in a two-dimensional lattice shape having a sub-wavelength period. In such a configuration, the support portion 11 is a periodic structure. And the periodic element which a periodic structure has is the recessed part 11H recessed from a reference plane by using the surface of the support part 11 as a reference plane. One end of the periodic element is an opening provided in each recess 11H, and the other end of the periodic element is a bottom surface provided in each recess 11H.

Also in this case, the metal layer 61 has a shape that follows the surface shape of the periodic structure, and the dielectric layer 62 has a shape that follows the surface shape of the metal layer 61. And the 1st metal layer 23 is located in the mesh shape surrounding the opening part of each recessed part 11H, and the 2nd metal layer 42 is located in the bottom face of each recessed part 11H. A network-like dielectric layer 71 is positioned on the first metal layer 23, and a dielectric layer 72 arranged in a two-dimensional lattice pattern is positioned on the second metal layer 42. At this time, a lattice structure made of a metal and a dielectric is formed by each second metal layer 42 and a mesh-like portion surrounding each second metal layer 42 in the support portion 11. In addition, the dielectric layer 72 located on the second metal layer 42 and the first metal layer 23 also form a lattice structure made of a metal and a dielectric. When the color filter is irradiated with light, the sub-pixel 10A transmits light in a specific wavelength region due to plasmon resonance occurring in the layer having these lattice structures. Even with such a configuration, the effects according to the above (9) to (11) can be obtained.
-The structure of the optical filter of 2nd Embodiment may be applied to the filter used for an image pick-up element similarly to 1st Embodiment.

  A2 ... isolated region, A3 ... peripheral region, L1 ... external light, EP1, EP2, LA, LP1, LP2, LR, LR1, LR2 ... light, LT ... square, PT ... structural period, T2, T3, T4, T5 T6, T7 ... thickness, W4, WT ... width, WP ... shortest width, 1 ... color filter, 2 ... light source device, 10A ... subpixel, 10S ... front surface, 10T ... back surface, 11 ... support portion, 11T ... projection 11H... Recess, 21... First lattice layer, 22... First dielectric layer, 23... First metal layer, 31... Intermediate lattice layer, 32 ... First intermediate dielectric layer, 32 A. 34 ... second intermediate dielectric layer, 41 ... second lattice layer, 42 ... second metal layer, 43,44 ... second dielectric layer, 45 ... protective layer, 51 ... upper lattice layer, 52 ... first upper dielectric layer Body layer, 53 ... second upper dielectric layer, 61 ... metal layer, 62 ... dielectric layer, 120 ... optical fiber Motor, 121 ... filter element, 130 ... light receiving element group, 131 ... light-receiving element, 140 ... imaging element.

Claims (14)

A plurality of filter elements that selectively transmit light in a specific wavelength region;
The filter element is a periodic structure composed of a dielectric, the periodic structure including a plurality of periodic elements arranged in a two-dimensional lattice, a metal layer located on the surface of the periodic structure, With
In the periodic structure, a plane in which the plurality of periodic elements are arranged is a reference plane,
The periodic element is either one of a protrusion having one end on the reference surface and projecting from the reference surface, and a hole having one end on the reference surface and recessed from the reference surface,
The metal layer includes a first metal layer having a mesh shape surrounding the one end of each periodic element in the reference plane, and a second metal layer located at the other end of each periodic element,
The structural period of the periodic element is a sub-wavelength period below the wavelength region that the filter element transmits,
A ratio of the width of the periodic element to the structural period in each direction along the two-dimensional lattice is 0.30 or more and 0.65 or less;
The metal layer has a negative real part of the complex dielectric constant for light in the visible region,
The thickness of the said metal layer is 1/10 or less of the distance of the said one end part in the said periodic element, and the said other end part. Optical filter. The optical filter according to claim 1, wherein a distance between the one end and the other end of the periodic element is 100 nm or more and 200 nm or less. The optical filter according to claim 1, wherein a thickness of the metal layer is 15 nm or less. The periodic element is the protrusion;
The optical filter according to any one of claims 1 to 3, wherein a ratio of a width of the periodic element to the structural period in each direction along the two-dimensional grating is 0.5 or less. The optical filter according to any one of claims 1 to 4, wherein the material constituting the metal layer includes any one metal material selected from the group consisting of aluminum, tantalum, silver, and gold. A dielectric layer located on the surface of the metal layer and having a shape following the surface shape of the metal layer;
The optical filter according to any one of claims 1 to 5, wherein a thickness of the dielectric layer is equal to or less than a distance between the one end and the other end of the periodic element. The optical filter according to claim 6, wherein the dielectric layer has a thickness of 200 nm or less. The material constituting the dielectric layer includes an oxide of any one material selected from the group consisting of titanium, niobium, aluminum, tantalum, hafnium, zirconium, silicon, and magnesium. Optical filter. The optical filter is a filter provided in a display device,
9. The plurality of filter elements included in the optical filter include a plurality of types of the filter elements that selectively transmit light in a wavelength region specific to each type. 10. Optical filter. The optical filter according to claim 1, wherein the optical filter is a filter provided in an imaging device. An optical filter according to any one of claims 1 to 9,
A light source device that causes light in a visible region to enter the filter element. An optical filter according to any one of claims 1 to 8, 10;
A light receiving element that receives light transmitted through the filter element and converts the light into an electrical signal. A method of manufacturing an optical filter comprising a plurality of filter elements that selectively transmit light in a specific wavelength region,
Forming the filter element comprises:
By transferring the unevenness of the intaglio to the resin coated on the surface of the base material, the periodic element that is a protrusion or a bottomed hole when viewed from the direction facing the surface of the base material is the filter element A periodic structure located in a two-dimensional lattice having a sub-wavelength period equal to or less than the wavelength region through which the periodic element is transmitted, wherein the periodic element has a structure period of the periodic element in each direction along the two-dimensional grating. A first step of forming the periodic structure having a width ratio of 0.30 or more and 0.65 or less;
A metal layer having a shape that follows the surface shape of the periodic structure on the periodic structure, wherein the real part of the complex dielectric constant for light in the visible region is negative. A second step of forming a thickness of 1/10 or less of a distance between one end of the periodic element and the other end of the periodic element located on a plane in which the plurality of periodic elements are arranged in the periodic structure; A method for manufacturing an optical filter. A third step of forming a dielectric layer having a shape following the surface shape of the metal layer on the metal layer to a thickness equal to or less than the distance between the one end and the other end of the periodic element. The method for producing an optical filter according to claim 13.

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