JP2021190481A - Color imaging device and electronic apparatus - Google Patents

Abstract

To make focus and separate each wavelength region component of incident light into colors in a correspondent photoelectric conversion layer in a vertical color separation type color imaging device.SOLUTION: The present invention relates to a color imaging device comprising: a light transmission layer through which light of a first wavelength region, light of a second wavelength region and light of a third wavelength region are transmitted; a first photoelectric conversion layer which absorbs the light of the first wavelength region and performs photoelectric conversion; a first signal readout circuit which reads out signal charge generated in the first photoelectric conversion layer; a second photoelectric conversion layer which absorbs the light of the second wavelength region and performs photoelectric conversion; a second signal readout circuit which reads out signal charge generated in the second photoelectric conversion layer; a third photoelectric conversion layer which absorbs the light of the third wavelength region and performs photoelectric conversion; and a third signal readout circuit which reads out signal charge generated in the third photoelectric conversion layer. The light transmission layer includes a light transmission film and first, second and third microstructure arrays provided in the light transmission film and respectively condensing the light of the first, second and third wavelength regions.SELECTED DRAWING: Figure 1

Description

The present invention relates to a color image sensor and an electronic device, and particularly relates to a vertical color separation type color image sensor and an electronic device using the same.

The current camera uses two methods, a three-plate type that acquires a color image using three image sensors and a single plate type that acquires a color image using only one image sensor.

In the three-plate system, the incident light is color-separated into three primary colors, that is, red (R), green (G), and blue (B) by a color separation prism, and each image is acquired by three image pickup elements. Therefore, while the incident light can be efficiently used and high-quality imaging is possible, a color separation prism is required and miniaturization is difficult.

On the other hand, in the single plate type, an RGB color filter is arranged in-plane on one image sensor to separate colors. Therefore, while miniaturization is possible, since a color filter that absorbs incident light other than the light in a specific wavelength range is used, the light utilization efficiency is lower than that of the three-plate type, and the image quality is deteriorated.
As described above, the three-plate type and the single-plate type have advantages and disadvantages, and it is an issue to achieve both high image quality and miniaturization of the image sensor.

Therefore, a vertical color separation type color image sensor that performs color separation in the traveling direction of light has been developed. For example, an image pickup device in which three Si photodiodes are laminated on a silicon (Si) substrate is known (see Patent Document 1). This is to perform color separation by utilizing the difference in the penetration depth of red light, green light, and blue light into Si, and blue light, green light, and red light are performed from the upper part of the image pickup element on the incident side of the light. This is a method of acquiring a color image by absorbing light in order and generating a charge.

Also, as a laminated image sensor, an organic photoelectric conversion film that absorbs only green light and generates charge is placed on the upper part of the image sensor on the incident side of the light, and a Si photodiode with two layers laminated on the lower part. Is known as a method of absorbing blue light and red light in order from the incident side of light to generate a charge (see Patent Document 2). This is a method in which green light having an intermediate wavelength is acquired in the upper part, and color separation is performed based on the difference in penetration depth between red light and blue light having different wavelengths in the lower part.

On the other hand, an organic image pickup device in which an organic photoelectric conversion film that selectively absorbs only light in a specific wavelength range such as red light, green light, and blue light is laminated has been proposed. The organic image pickup element performs vertical color separation by a structure in which a signal readout circuit using an organic photoelectric conversion film having sensitivity only for red light, green light, and blue light and a light transmission type thin film transistor (TFT) are alternately laminated. It is a method. Specifically, for example, a device in which a readout circuit and three elements having an organic film formed on a glass substrate are laminated, and a device in which the organic photoelectric conversion film and the signal readout circuit at the bottom are replaced with a CMOS image sensor are disclosed. (Patent Document 3 and Patent Document 4).

On the other hand, in recent years, research on metasurface technology that controls the optical phase by arranging fine structures whose width and depth are smaller than the optical wavelength, which are made of a material having a higher refractive index than the light transmitting film inside the visible light transmitting film. Is widely used, and among them, a metal lens having a light-collecting function due to the arrangement of a fine structure imitating the parabolic phase distribution of an optical lens is attracting attention (Non-Patent Document 1).

Since it is possible in principle to change the focal length of this metal lens by controlling the phase distribution, it can be considered to be used as a method of vertical color separation. So far, three differently shaped rectangular microstructures for controlling the phases of red light, green light, and blue light have been rotated and arranged concentrically in the same plane, and parabolic control for each color of light has been performed. A method of expanding the axial chromatic aberration of red light, green light, and blue light by forming the above-mentioned phase distribution has been reported (Non-Patent Document 2).

Japanese Patent Publication No. 2002-513145 Japanese Unexamined Patent Publication No. 2017-174936 Japanese Unexamined Patent Publication No. 2005-51115 Japanese Unexamined Patent Publication No. 2019-102623

M. Khorasaninejad et al., Science 352, 1190 (2016). K. Li et al., Opt. Express 25, 21419 (2017).

However, in the method of Patent Document 1, there is a problem in color separability such that a certain amount of red light and green light are absorbed even in a blue light absorption region having a short distance on the light incident side.
Further, in the method of Patent Document 2, passing through the penetrating vias in each pixel unit complicates the manufacturing process, and the light receiving area is reduced by arranging the penetrating vias in the pixels, so that the light utilization efficiency is improved. There was a problem of decline.

In the methods of Patent Document 3 and Patent Document 4, a glass substrate and an intermediate layer are required between each of the three photoelectric conversion layers, and due to their structure, it is difficult to keep them within the focal depth of the optical lens of the camera. For example, if the second layer is set to be in focus, there is a problem that the first layer and the third layer are out of focus and the acquired image is deteriorated.
Further, regarding the expansion of axial chromatic aberration using the metal lens of Non-Patent Document 2, no specific application has been proposed so far, but if it is applied to a laminated image pickup element, it can be applied to each photoelectric conversion layer. It is considered that vertical color separation can be performed while focusing on all photoelectric conversion layers regardless of the interlayer distance. However, as in Non-Patent Document 2, a metal lens in which the fine structures are arranged in the same plane with the target of condensing three colors of red light, green light, and blue light is a standard single color as shown in Non-Patent Document 1. Compared to a metal lens that targets light collection (light collection efficiency of about 75 to 95%), the density of rectangular microstructures per target color is reduced, so that the light collection efficiency of each color is about 40 to 55%. There is a problem that it drops to.

The present invention has been made in view of the above-mentioned problems, and enables color separation by focusing on a photoelectric conversion layer corresponding to each wavelength range component of incident light, thereby reducing light collection efficiency. It is an object of the present invention to provide a vertical color separation type color image pickup element and an electronic device using the same, which are further facilitated in production.

(1) The first aspect of the present invention is, in order from the incident direction of light including light in at least the first wavelength region, light in the second wavelength region, and light in the third wavelength region.
A light transmitting layer that transmits at least the light in the first wavelength region, the light in the second wavelength region, and the light in the third wavelength region.
A first photoelectric conversion layer that absorbs light in the first wavelength region to perform photoelectric conversion and transmits light in the second wavelength region and light in the third wavelength region.
A first signal reading circuit that reads out the signal charge generated in the first photoelectric conversion layer, and
A second photoelectric conversion layer that absorbs light in the second wavelength range to perform photoelectric conversion and transmits light in the third wavelength range.
A second signal reading circuit that reads out the signal charge generated in the second photoelectric conversion layer, and
A third photoelectric conversion layer that absorbs light in the third wavelength range and performs photoelectric conversion,
A third signal reading circuit that reads out the signal charge generated in the third photoelectric conversion layer, and
It is a color image sensor equipped with
The light transmitting layer is
Light transmission film and
The first microstructure arrangement provided in the light transmitting film that concentrates the light in the first wavelength region on the first photoelectric conversion layer, and the light in the second wavelength region is the second. A second microstructure array that concentrates light on the photoelectric conversion layer, and a third microstructure array that concentrates light in the third wavelength range on the third photoelectric conversion layer.
A plurality of first microstructures constituting the first microstructure array, a plurality of second microstructures constituting the second microstructure array, and a third microstructure array. Each of the plurality of third microstructures has a refractive index larger than that of the light transmitting film, which is a color imaging device.

(2) The second aspect of the present invention is, in order from the incident direction of light including light in at least the first wavelength region, light in the second wavelength region, and light in the third wavelength region.
A light transmitting layer that transmits at least the light in the first wavelength region, the light in the second wavelength region, and the light in the third wavelength region.
A first photoelectric conversion layer that absorbs light in the first wavelength region to perform photoelectric conversion and transmits light in the second wavelength region and light in the third wavelength region.
A first signal reading circuit that reads out the signal charge generated in the first photoelectric conversion layer, and
A first interlayer insulating layer that transmits light in at least the second wavelength region and light in the third wavelength region,
A second photoelectric conversion layer that absorbs light in the second wavelength range to perform photoelectric conversion and transmits light in the third wavelength range.
A second signal reading circuit that reads out the signal charge generated in the second photoelectric conversion layer, and
A second interlayer insulating layer that transmits light in at least the third wavelength region,
A third photoelectric conversion layer that absorbs light in the third wavelength range and performs photoelectric conversion,
A third signal reading circuit that reads out the signal charge generated in the third photoelectric conversion layer, and
It is a color image sensor equipped with
The light transmitting layer is a first light transmitting film and a first fine particle that condenses light in the first wavelength range contained in the first light transmitting film on the first photoelectric conversion layer. With a structure array,
The first interlayer insulating layer has a second light transmitting film and a second photoelectric conversion layer that collects light in the second wavelength range contained in the second light transmitting film. It has 2 microstructure arrays and
The second interlayer insulating layer is a third light transmitting film and a third photoelectric conversion layer that collects light in the third wavelength range contained in the third light transmitting film. It has 3 microstructure arrays and
The refractive index of the plurality of first microstructures constituting the first microstructure arrangement is larger than the refractive index of the first light transmitting film, and the plurality of constituents of the second microstructure arrangement. The refractive index of the second microstructure is larger than the refractive index of the second light transmitting film, and the refractive index of the plurality of third microstructures constituting the third microstructure arrangement is the third. It is a color image pickup element having a refraction coefficient larger than that of the light transmissive film.

(3) In the color imaging device according to (1) or (2), each of the first photoelectric conversion layer, the second photoelectric conversion layer, and the third photoelectric conversion layer is the first photoelectric conversion layer. It may contain an organic material having sensitivity to light in a wavelength range, light in the second wavelength range, and light in the third wavelength range.

(4) In the color imaging device according to any one of (1) to (3), other than the first microstructure array, the second microstructure array, and the third microstructure array. The light transmitting layer and the light-shielding layer that shields the light including at least the light in the first wavelength region, the light in the second wavelength region, and the light in the third wavelength region incident on the region of the above. It may be provided between the first photoelectric conversion layer and the like.

(5) A third aspect of the present invention is the color image sensor according to any one of (1) to (4) above, an optical system that incidents light on the color image sensor, and an output from the color image sensor. It is an electronic device provided with an image processing circuit that performs image processing of an electric signal to be generated.

According to the present invention, color separation is possible by focusing on the corresponding photoelectric conversion layer for each wavelength range component of the incident light, regardless of the thickness of the laminated film, the number of photoelectric conversion layers, and the stacking order.
Further, according to the present invention, it is possible to prevent a decrease in light collection efficiency and facilitate the manufacture of a color image pickup device.

It is a schematic cross-sectional view which shows the structure of one pixel of the color image sensor of 1st Embodiment of this invention. It is sectional drawing which shows the light transmission layer of one pixel of the color image sensor shown in FIG. 1. It is a top view of one pixel of the color image sensor shown in FIG. 1. 3 is a cross-sectional view showing a first to third microstructure arrangement, a light-shielding layer, and a first photoelectric conversion layer of the light transmitting layer in the XX'cross section of FIG. (A) is a perspective view for explaining the shape of the microstructure constituting the first to third microstructure arrangement, and (B) is a top view of the microstructure. It is a top view which shows the arrangement of the 1st microstructure which constitutes the 1st microstructure arrangement. It is a top view which shows the arrangement of the 2nd microstructure which constitutes the 2nd microstructure arrangement. It is a top view which shows the arrangement of the 3rd microstructure which constitutes the 3rd microstructure arrangement. It is a characteristic diagram which shows the relationship between the wavelength of light and the light collection efficiency. It is a characteristic diagram which shows the relationship of the optical phase Φ with respect to the orientation angle θ of the long axis of a fine structure. It is a characteristic diagram which shows the relationship between the radius of each microstructure arrangement and the optical phase Φ. It is a figure for _{demonstrating the focal lengths f R} , f _G , and f _B of red light, green light, and blue light. It is a characteristic diagram which shows the relationship between the radius r and the optical phase Φ of each microstructure when f _R <f _G <f _B. It is a figure for _{demonstrating the focal lengths f B} , f _G , f _R of blue light, green light, and red light. It is a characteristic diagram which shows the relationship between the radius r and the optical phase Φ of each microstructure when f _B <f _G <f _R. It is a figure for _{demonstrating the focal lengths f R} , f _G , and f _B of red light, green light, and blue light. It is a characteristic diagram which shows the relationship between the radius r and the optical phase Φ of each microstructure when f _G <f _B <f _R. It is a figure for _{demonstrating the focal lengths f R} , f _B , and f _G of red light, blue light, and green light. It is a schematic cross-sectional view which shows the structure of one pixel of the color image sensor of the 2nd Embodiment of this invention. FIG. 19 is a cross-sectional view showing a light transmission layer, a first interlayer insulating layer, and a second interlayer insulating layer of one pixel of the color image sensor shown in FIG. It is a block diagram which shows the example which used the color image sensor of 1st Embodiment in a digital still camera.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First Embodiment)
FIG. 1 is a schematic cross-sectional view showing the configuration of one pixel of the color image sensor according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a light transmission layer of one pixel of the color image sensor shown in FIG. FIG. 3 is a top view of one pixel of the color image sensor shown in FIG. FIG. 4 is a cross-sectional view showing a first to third microstructure arrangement, a light shielding layer, and a first photoelectric conversion layer of the light transmitting layer in the XX'cross section of FIG. In addition, in FIG. 1 and FIG. 2, the z direction indicates the stacking direction of layers.
As shown in FIG. 1, one pixel of the color image sensor 1A according to the present embodiment has a light transmission layer 10, a first photoelectric conversion layer 11, and a first signal readout circuit layer 12 in order from the incident direction of light. A first interlayer insulating layer 13, a second photoelectric conversion layer 14, a second signal readout circuit layer 15, a second interlayer insulating layer 16, a third photoelectric conversion layer 17, and a third signal readout circuit layer 18. It is equipped with. As shown in FIGS. 3 and 4, a light-shielding layer 19 is provided between the light transmitting layer 10 and the first photoelectric conversion layer 11. Each layer from the light transmission layer 10 to the third signal readout circuit layer 18 and the light-shielding layer 19 are provided on the insulating substrate 20.

As the material of the insulating substrate 20, glass, silicon, silicon oxide, magnesium oxide, nickel oxide, aluminum oxide, plastic film, polyimide, polyethylene terephthalate (PET) and the like can be used.

In FIG. 1, an example in which a third signal readout circuit layer 18 is formed on an insulating substrate 20, and a light transmission layer 10 is sequentially laminated from a third photoelectric conversion layer 17 on the third signal readout circuit layer 18. However, when the insulating substrate 20 has light transmittance, the light transmitting layer 10 is formed on the insulating substrate 20, and the first photoelectric conversion layer 11 to the third are formed on the light transmitting layer 10. The signal readout circuit layers 18 may be sequentially laminated.
1 to 4 show only one pixel of the color image sensor 1A, but the color image sensor 1A includes pixels arranged vertically and horizontally in an array.

Hereinafter, each layer from the light transmission layer 10 to the third signal readout circuit layer 18 and the light-shielding layer 19 formed on the insulating substrate 20 will be described.

<Light transmitting layer 10>
As shown in FIG. 2, the light transmitting layer 10 is a first microstructure arrangement provided in the light transmitting film 100 and the light transmitting film 100 at different positions in the depth direction in order from the incident direction of light. It includes 101, a second microstructure array 102, and a third microstructure array 103. When infrared light is not detected, it is desirable to provide a filter that absorbs infrared light on the light transmitting layer 10.
The first microstructure array 101, the second microstructure array 102, and the third microstructure array 103 have a circular shape when viewed from the incident direction of light. The light transmitting film 100 has a square shape, and a first microstructure array 101, a second microstructure array 102, and a third microstructure array 103 are provided in a part of the light transmitting film 100. ..
The first microstructure array 101 condenses blue light (peak wavelength 450 nm), which is light in the first wavelength region, among the incident light, and causes the incident light to be incident on the first photoelectric conversion layer 11. The second microstructure array 102 condenses green light (peak wavelength 500 to 540 nm), which is light in the second wavelength region, among the incident light, and causes the incident light to be incident on the second photoelectric conversion layer 14. The third microstructure array 103 collects red light (peak wavelength 650 nm), which is light in the third wavelength region, among the incident light, and causes the incident light to be incident on the third photoelectric conversion layer 17. The light in the first wavelength range is blue light (peak wavelength 450 nm), the light in the second wavelength range is green light (peak wavelength 500 to 540 nm), and the light in the third wavelength range is red light (peak wavelength 650 nm). ), But even if the order of the light of each color is changed, the same effect is obtained.
In FIG. 1, the blue light that is the light in the first wavelength region is shown by a solid line, the green light that is the light in the second wavelength range is shown by a broken line, and the red light that is the light in the third wavelength range is shown by a broken line. It is shown by a single point chain line.

The light transmitting film 100 is preferably formed of an insulating material having light transmission. For example, silicon, silicon oxide, silicon oxide, magnesium oxide, nickel oxide, aluminum oxide, a plastic film, polyimide, or polyethylene terephthalate (PET) can be used.

Details of the first microstructure array 101, the second microstructure array 102, and the third microstructure array 103 will be described later.

<Third 1st to 3rd photoelectric conversion layers 11, 14, 17>
The upper and lower surfaces of the first photoelectric conversion layer 11 are sandwiched between the first pixel electrode and the first counter electrode, and blue light is converted into an electric signal. The upper and lower surfaces of the second photoelectric conversion layer 14 are sandwiched between the second pixel electrode and the second counter electrode, and green light is converted into an electric signal. The upper and lower surfaces of the third photoelectric conversion layer 17 are sandwiched between the third pixel electrode and the third counter electrode, and red light is converted into an electric signal. The first to third photoelectric conversion layers 11, 14, and 17 have a rectangular shape when viewed from the incident direction of light.

Each of the first to third photoelectric conversion layers 11, 14 and 17 is required to absorb light in a specific wavelength range and transmit light in another wavelength range, and an organic material is suitable. Although it can be used, an inorganic material having similar characteristics and a material containing the same may be used alone, or two or more kinds may be mixed or laminated. Examples of the organic material used for the first photoelectric conversion layer 11 and having sensitivity only to blue light include coumarin derivatives and porphyrin derivatives. Examples of the organic material used for the second photoelectric conversion layer 14 having sensitivity only to green light include a quinacridone derivative and a perylene derivative. Examples of the organic material used for the third photoelectric conversion layer 17 and having sensitivity only to red light include a phthalocyanine derivative and a naphthalocyanine derivative.

It is desirable that the first to third pixel electrodes and the first to third counter electrodes are made of a material having light transmittance. For example, examples of the light-transmitting material include indium tin oxide (ITO), fluorine-doped tin oxide (FTO), indium oxide / zinc oxide (IZO), zinc oxide (ZnO), tin oxide (SnO ₂ ), and the like. Be done.

<Shading layer 19>
As shown in FIG. 3, the light-shielding layer 19 is provided between the light transmitting layer 10 and the first photoelectric conversion layer 11, and is formed on a rectangular first photoelectric conversion layer 11 in a circular shape. It is provided to shield the four corners generated by the formation of the microstructure array 101, the second microstructure array 102, and the third microstructure array 103. The light-shielding layer 19 is a component (light in the first wavelength range) transmitted by the first microstructure array 101, the second microstructure array 102, and the third microstructure array 103 without being condensed. , Light including light in the second wavelength range and light in the third wavelength range) is removed. The light-shielding layer 19 may be provided on the light-transmitting layer 10.

<Third signal readout circuit layers 12, 15, 18>
The one-pixel signal readout circuit layers 12, 15, and 18 include a TFT circuit connected to a first pixel electrode, a second pixel electrode, and a third pixel electrode, respectively. A configuration example of the TFT circuit is described in, for example, Patent Document 4, and can be applied to the signal readout circuit layers 12, 15, and 18 of the present embodiment. For example, Patent Document 4 describes a configuration of a 1-pixel 1-transistor provided with one selection TFT to which a pixel electrode and a source or drain are connected. Further, Patent Document 4 is provided with a reset TFT that resets a pixel electrode, an amplification TFT that connects a pixel electrode and a gate, and a selection TFT that is connected to the source or drain of the amplification TFT. The configuration of the three transistors is described.
As the TFT used in the signal readout circuit layers 12, 15 and 18, it is preferable to use a TFT made of a light-transmitting semiconductor material. Examples of such a semiconductor material include zinc oxide (ZnO), indium, gallium, zinc oxide (InGaZnO), which are amorphous oxide semiconductors, and the like. In particular, the signal readout circuit layer 12 is a semiconductor material having visible light transmission to transmit at least green light and red light, and the signal readout circuit layer 15 is a semiconductor material having visible light transmission to transmit at least red light. It is desirable to use.

<First and second interlayer insulating layers 13, 16>
It is desirable that the interlayer insulating layers 13 and 16 are formed of an insulating material having light transmittance, similarly to the light transmitting layer 10. For example, silicon, silicon oxide, silicon oxide, magnesium oxide, nickel oxide, aluminum oxide, a plastic film, polyimide, or polyethylene terephthalate (PET) can be used. In particular, the first interlayer insulating layer 13 is an insulating material having visible light transmission to transmit at least green light and red light, and the second interlayer insulating layer 16 is visible light transmitting to transmit at least red light. It is desirable to use an insulating material having.

The constituent layers of the color image sensor shown in FIG. 1 have been described above. Hereinafter, the first microstructure array 101, the second microstructure array 102, and the third microstructure array 103 included in the light transmitting layer 10 will be further described.

<First to third microstructure arrays 101, 102, 103>
FIG. 5A is a perspective view for explaining the shape of the microstructures constituting the first to third microstructure arrays, and FIG. 5B is a top view of the microstructures. 6 to 8 are top views showing the arrangement of the first to third microstructures constituting the first to third microstructure arrangements.

As shown in FIG. 6, the first microstructure array 101 is configured by arranging the first microstructure 201. As shown in FIG. 7, the second microstructure array 102 is configured by arranging the second microstructure 202. As shown in FIG. 8, the third microstructure array 103 is configured by arranging the third microstructure 203. The concentric circles shown in FIGS. 6 to 8 do not indicate boundaries, and facilitates understanding of the arrangement of the first microstructure 201, the second microstructure 202, and the third microstructure 203. It is described for the purpose. In FIGS. 6 to 8, r indicates a radial distance from the center.

As shown in FIGS. 5A and 5B, the first to third microstructures 201, 202 and 203 have the same height h and a rectangular cross-sectional shape. The materials of the first to third microstructures 201, 202 and 203 are made of a material having a refractive index larger than that of the material of the light transmitting film 100 of the light transmitting layer 10.
As shown in FIGS. 6 to 8, in the first microstructure array 101, the second microstructure array 102, and the third microstructure array 103, the microstructures 201, 202, and 203 are blue light. , Green light, and red light are arranged concentrically so that the phase distributions corresponding to each are parabolic.
The microstructure 201 of the first microstructure array 101, the microstructure 202 of the second microstructure array 102, and the microstructure 203 of the third microstructure array 103 are each formed on the same plane. Has been done.
The distance (pitch) between the first microstructures 201 of the first microstructure array 101 is equal to or less than the wavelength of blue light, and the interval (period) may or may not be constant. good. The distance (pitch) between the second microstructures 202 of the second microstructure array 102 is less than or equal to the wavelength of the green light, and the interval (period) may or may not be constant. good. The distance (pitch) between the third microstructures 203 of the third microstructure array 103 is less than or equal to the wavelength of the red light, and the interval (period) may or may not be constant. good.

The dimensions of the first to third microstructures 201, 202 and 203 can be set to the following values.
The width and depth of the first microstructure 201 are l _B and w _B , the width and depth of the second microstructure 202 are l _G and w _G , and the width and depth of the third microstructure 203 are l _R. When and w _R , the relationship of _{l B} <l _G <l _R and w _B <w _G <w _{R is established.} Specifically, as shown in FIG. 9, the first to third microstructures 201, 202, and 203 need to be designed so as to exhibit light collection efficiency only for blue light, green light, and red light, respectively. For example, it is desirable that _{l B} = 80 nm, w _B = 42 nm, l _G = 91 _{nm, w G} = 67 nm, l _R = 131 nm, and w _{R = 102 nm.} FIG. 9 is a characteristic diagram showing the relationship between the wavelength of light and the light collection efficiency.
Further, it is desirable that the height h of the first to third microstructures 201, 202 and 203 is about h = 400 nm. The pitch p of the first to third microstructures 201, 202, 203 in the first microstructure array 101, the second microstructure array 102, and the third microstructure array 103 is p = 200 nm. It is desirable to set the degree.
For example, assuming that the pixel size of the image pickup element is 3 μm, the first to third microstructures 201 in the first microstructure array 101, the second microstructure array 102, and the third microstructure array 103, The number of each of 202 and 203 is about 700 to 850, respectively.

As a material for producing the microstructures 201, 202, and 203, materials generally used for producing a metasurface can be applied, and examples thereof include silicon (Si) and silicon nitride (SiN).
Preferred material combinations of the microstructures 201, 202, 203 and the light transmitting film of the light transmitting layer 10 include silicon and silicon oxide, or silicon nitride and silicon oxide. Further, as a combination of the materials of the microstructures 201, 202, 203 and the light transmitting film of the light transmitting layer 10, the microstructure is made of silicon, and the light transmitting film of the light transmitting layer 10 is made of silicon oxide, aluminum oxide, or polyimide. And so on.

When the combination of the materials of the microstructures 201, 202, 203 and the light transmitting film of the light transmitting layer 10 is silicon and silicon oxide, or silicon nitride and silicon oxide, the first to third microstructures 201 , 202 and 203 can have the following values.
The width and depth of the first microstructure 201 are l _B and w _B , the width and depth of the second microstructure 202 are l _G and w _G , and the width and depth of the third microstructure 203 are l _R. And w _R , for l _B , w _B , l _G , w _G , l _R , w _R , l _B <l _G <l _R and w _B <w _G <w _R are satisfied and below the optical wavelength. It is desirable that it is (<~ 500 nm). The height h of the first to third microstructures 201, 202, and 203 is preferably 1500 nm or less, and more preferably 700 nm or less. The vertical and horizontal periods of the arrangement of the first to third microstructures 201, 202, and 203 are all set to the visible light wavelength or less, and the period may or may not be constant.

FIG. 10 is a characteristic diagram showing the relationship of the optical phase Φ with respect to the orientation angle θ of the long axis of the fine structure. As shown in FIG. 5B, the orientation angle θ is an angle when the lateral direction (left-right direction) of FIGS. 6 to 8 is used as a reference line. In the first microstructure array 101, the second microstructure array 102, and the third microstructure array 103, the orientation angle θ of the major axis of each microstructure is in the range of 0 to 90 degrees. _{L B} and w _B , l _G and w _G , and l _R and w _R are determined so that the respective optical phases Φ of red light, green light, and blue light change linearly between 0 and π.
Further, as shown in FIG. 11, the first microstructure array 101, the second microstructure array 102, and the third microstructure array 103 each have an optical phase Φ (alignment angle θ (r) on the long axis). ) Corresponds to), and the first to third microstructures 201, 202, and 203 are arranged so as to have a parabolic shape.
As a result, since the orientation angle θ and the optical phase Φ have a linear relationship, the optical phases Φ (r) of the red light, green light, and blue light passing through the microstructure arrangements 101, 102, and 103 in the light transmitting layer 10. ) Is also parabolic.

Since dΦ / dr and the focal length have a negative correlation, the focal length can be controlled by changing dθ / dr. In the case of this embodiment, dΦ / dr increases in the order of blue light, green light, and red light. Therefore, as shown in FIG. 12, the focal length f _{R in the order of red light, green light, and blue light.} , F _G and f _B are increasing, and the difference between the focal length of blue light and the focal length of red light is expanded to about 10 μm.
By changing dθ / dr, _{the sizes of the focal lengths f R} , f _G , and f _B can be arbitrarily changed, and the order thereof is FIG. 13 and FIG. 14, FIGS. 15 and 16, FIG. 17 and 18 may be different as shown in FIG. 13, FIG. 15 and FIG. 17 show the radius and optical phase Φ of each microstructure when _{f R} <f _G <f _B , f _B <f _G <f _R , f _G <f _B <f _{R, respectively.} It is a characteristic diagram which shows the relationship with. 14, 16 and 18, the blue light, green light, the focal point of the red light distance _{f B,} f G, diagram for explaining the _{f R,} red light, green light, the focal length _f R of the blue light, It is _{a figure for demonstrating f G} , f _B , and the figure for demonstrating the focal length f _R , f _B , f _G of red light, blue light, and green light.
Further, if the cross-sectional area of the microstructure when viewed from above satisfies the condition that the cross-sectional area is larger in the order of blue light, green light, and red light, and has the same effect, the cross-section of the microstructure The shape does not have to be rectangular, and for example, the cross-sectional shape may be an ellipse or a polygon.

According to the color imaging device of the present embodiment described above, since the first to third microstructure arrays 101 to 103 are arranged in a laminated structure in the light transmitting layer 10, they are arranged on the same surface. Compared with Become.
Further, according to the color imaging device of the present embodiment, the first to third microstructure arrangements 101 to 103 are used regardless of the presence or absence of a substrate or a laminated film, the thickness thereof, the number of photoelectric conversion layers, and the stacking order. , Each wavelength range component of the incident light can be focused and color-separated by the corresponding photoelectric conversion layer.

(Second Embodiment)
FIG. 19 is a schematic cross-sectional view showing the configuration of one pixel of the color image sensor according to the second embodiment of the present invention. FIG. 20 is a cross-sectional view showing a light transmission layer, a first interlayer insulating layer, and a second interlayer insulating layer of one pixel of the color image sensor shown in FIG. In FIGS. 19 and 20, the same components as those in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted.
In the color imaging device 1B of the present embodiment, the first microstructure array 101, the second microstructure array 102 and the third microstructure array 103 are the light transmission layer 10, the first interlayer insulating layer 13 and It has the same configuration as the color imaging device 1A of the first embodiment except that it is provided on each of the second interlayer insulating layers 16.

In the color image pickup element 1B of the present embodiment, as shown in FIG. 19, the light transmission layer 10 is a light transmission film 100 serving as a first light transmission film and a first light transmission film 100 provided in the light transmission film 100. Includes the microstructure array 101. Further, the first interlayer insulating layer 13 includes a light transmitting film 130 serving as a second light transmitting film and a second microstructure array 102 provided in the light transmitting film 130. Further, the second interlayer insulating layer 16 includes a light transmitting film 160 serving as a third light transmitting film and a third microstructure arrangement 103 provided in the light transmitting film 160.
In this embodiment, as shown in FIG. 19, the focal length of the blue light of the first microstructure array 101 is set to be the same as that of the first embodiment. Since the second microstructure array 102 is included in the first interlayer insulating layer 13, the focal length of the green light of the second microstructure array 102 is set shorter than that of the first embodiment. Further, since the third microstructure array 103 is included in the second interlayer insulating layer 16, the focal length of the red light of the third microstructure array 103 is set shorter than that of the first embodiment.

The refractive index of the plurality of first microstructures 201 constituting the first microstructure array 101 is larger than the refractive index of the light transmitting film 100, and the plurality of second components constituting the second microstructure array 102 are formed. The refraction of the microstructure 202 is larger than the refraction of the light transmitting film 130, and the refraction of the plurality of third microstructures 203 constituting the third microstructure arrangement 103 is the refraction of the light transmitting film 160. Greater than the rate.

According to the color imaging device of the present embodiment described above, as in the first embodiment, the light transmission layer 10, the first interlayer insulating layer 13 and the second interlayer insulating layer 16 are each first. Since the microstructure array 101, the second microstructure array 102, and the third microstructure array 103 are arranged, the light collection efficiency of the lens is lowered as compared with the case where they are arranged on the same surface. Without the need for a first microstructure array 101 in the light transmissive layer 10, a second microstructure array 102 in the first interlayer insulating layer 13, and a third microstructure in the second interlayer insulating layer 16. Since the structure array 103 can be manufactured by integral formation, the production can be facilitated.
Further, according to the color imaging device of the present embodiment, the first to third microstructure arrangements 101 to 103 are used regardless of the presence or absence of a substrate or a laminated film, the thickness thereof, the number of photoelectric conversion layers, and the stacking order. , Each wavelength range component of the incident light can be focused and color-separated by the corresponding photoelectric conversion layer.

(Third Embodiment)
The color image pickup element of the first embodiment or the second embodiment described above is used for an image pickup device such as a digital still camera, a video camera, a security camera, and an electronic device such as a communication device having an image pickup function such as a mobile phone. Can be done. Hereinafter, as an example, an example in which the color image sensor of the first embodiment is used in a digital still camera will be described. The color image sensor of the second embodiment may be used instead of the color image sensor of the first embodiment.

FIG. 21 is a block diagram showing an example in which the color image sensor of the first embodiment is used in a digital still camera.
As shown in FIG. 21, the digital still camera includes a color image sensor 1A of the first embodiment, a lens 2 which is an optical system for condensing light on the color image sensor 1A, an image processing circuit 3, a liquid crystal monitor 4, and an electronic view. It includes a finder 5 and a recording medium 6 such as a memory card.
The light of the subject passing through the lens 2 is converted into an electric signal for each pixel by the color image pickup element 1A, and image processing such as white balance processing, demosaic processing, and gamma correction processing is performed by the image processing circuit 3. The user can see the image of the subject by using the liquid crystal monitor 4 and the electronic viewfinder 5. The digital image data is stored in the recording medium 6. Since the configuration of the digital still camera is already known, detailed description thereof will be omitted.

Although the first embodiment, the second embodiment and the third embodiment described above are preferred embodiments of the present invention, the scope of the present invention is not limited to the above-described embodiments, and the gist of the present invention is described. It is possible to carry out in a form with various changes within a range that does not deviate.

For example, the light detected by the color image pickup device of the present embodiment may detect not only visible light such as red light, green light, and blue light, but also light such as infrared light and ultraviolet light.
Specifically, Patent Document 4 (Japanese Unexamined Patent Publication No. 2019-102623) detects near infrared rays (wavelength 750 to 900 nm) in addition to three photoelectric conversion layers that detect light in three wavelength ranges of visible light. An example of adding a photoelectric conversion layer is described, and the color image sensor of the present embodiment can also be a color image sensor compatible with near infrared rays. As described above, the color image sensor corresponding to near infrared rays can be used as the color image sensor of the security camera.

1A, 1B color image sensor 10 Light transmission layer 11 First photoelectric conversion layer 12 First signal readout circuit layer 13 First interlayer insulation layer 14 Second photoelectric conversion layer 15 Second signal readout circuit layer 16 Second Interlayer insulation layer 17 Third photoelectric conversion layer 18 Third signal readout circuit layer 19 Light-shielding layer 20 Insulation substrate

Claims (5)

In order from the incident direction of the light including at least the light in the first wavelength region, the light in the second wavelength region, and the light in the third wavelength region.
A light transmitting layer that transmits at least the light in the first wavelength region, the light in the second wavelength region, and the light in the third wavelength region.
A first photoelectric conversion layer that absorbs light in the first wavelength region to perform photoelectric conversion and transmits light in the second wavelength region and light in the third wavelength region.
A first signal reading circuit that reads out the signal charge generated in the first photoelectric conversion layer, and
A second photoelectric conversion layer that absorbs light in the second wavelength range to perform photoelectric conversion and transmits light in the third wavelength range.
A second signal reading circuit that reads out the signal charge generated in the second photoelectric conversion layer, and
A third photoelectric conversion layer that absorbs light in the third wavelength range and performs photoelectric conversion,
A third signal reading circuit that reads out the signal charge generated in the third photoelectric conversion layer, and
It is a color image sensor equipped with
The light transmitting layer is
Light transmission film and
The first microstructure arrangement provided in the light transmitting film that concentrates the light in the first wavelength region on the first photoelectric conversion layer, and the light in the second wavelength region is the second. A second microstructure array that concentrates light on the photoelectric conversion layer, and a third microstructure array that concentrates light in the third wavelength range on the third photoelectric conversion layer.
A plurality of first microstructures constituting the first microstructure array, a plurality of second microstructures constituting the second microstructure array, and a third microstructure array. A color imaging device in which the refractive index of each of the plurality of third microstructures is larger than the refractive index of the light transmitting film. In order from the incident direction of the light including at least the light in the first wavelength region, the light in the second wavelength region, and the light in the third wavelength region.
A light transmitting layer that transmits at least the light in the first wavelength region, the light in the second wavelength region, and the light in the third wavelength region.
A first photoelectric conversion layer that absorbs light in the first wavelength region to perform photoelectric conversion and transmits light in the second wavelength region and light in the third wavelength region.
A first signal reading circuit that reads out the signal charge generated in the first photoelectric conversion layer, and
A first interlayer insulating layer that transmits light in at least the second wavelength region and light in the third wavelength region,
A second photoelectric conversion layer that absorbs light in the second wavelength range to perform photoelectric conversion and transmits light in the third wavelength range.
A second signal reading circuit that reads out the signal charge generated in the second photoelectric conversion layer, and
A second interlayer insulating layer that transmits light in at least the third wavelength region,
A third photoelectric conversion layer that absorbs light in the third wavelength range and performs photoelectric conversion,
A third signal reading circuit that reads out the signal charge generated in the third photoelectric conversion layer, and
It is a color image sensor equipped with
The light transmitting layer is a first light transmitting film and a first fine particle that condenses light in the first wavelength range contained in the first light transmitting film on the first photoelectric conversion layer. With a structure array,
The first interlayer insulating layer has a second light transmitting film and a second photoelectric conversion layer that collects light in the second wavelength range contained in the second light transmitting film. It has 2 microstructure arrays and
The second interlayer insulating layer is a third light transmitting film and a third photoelectric conversion layer that collects light in the third wavelength range contained in the third light transmitting film. It has 3 microstructure arrays and
The refractive index of the plurality of first microstructures constituting the first microstructure arrangement is larger than the refractive index of the first light transmitting film, and the plurality of constituents of the second microstructure arrangement. The refractive index of the second microstructure is larger than the refractive index of the second light transmitting film, and the refractive index of the plurality of third microstructures constituting the third microstructure arrangement is the third. A color image pickup element that is larger than the refractive index of the light transmissive film. Each of the first photoelectric conversion layer, the second photoelectric conversion layer, and the third photoelectric conversion layer has light in the first wavelength region, light in the second wavelength region, and the third wavelength. The color image sensor according to claim 1 or 2, which contains an organic material having sensitivity to light in the region. Light in at least the first wavelength range incident on a region other than the first microstructure array, the second microstructure array, and the third microstructure array, the second wavelength range. 1 The color image pickup device according to the section. The color image sensor according to any one of claims 1 to 4, an optical system that incidents light on the color image sensor, and an image processing circuit that performs image processing of an electric signal output from the color image sensor. , Equipped with an electronic device.

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