CN100472791C - Image pickup device - Google Patents

Abstract

The imaging element (1) is provided with a filter (2) for extracting a specific color component in incident light, and an incident light receiving element (3) for observing the incident light via the filter (2). The filter (2) includes a transparent filter (2W), a yellow filter (2Y) for extracting a yellow component, and a red filter (2R) for extracting a red component.

Description

camera element

technical field

The present invention relates to an imaging device with excellent color balance and color reproducibility.

Background technique

An imaging device conventionally used in a digital still camera or a video camera includes an imaging element. The imaging element is provided as a pair of a light-receiving element such as a CMOS or a CCD, and a color filter, and captures a color image.

The light receiving element is a component that outputs an electrical signal corresponding to the intensity of incident light. This light receiving element only detects the brightness of incident light, and does not discriminate the color of incident light. Therefore, a color filter is provided on the light-incident side of each light-receiving element (hereinafter also referred to as the light-incident side) to extract a specific color component from the incident light. Thus, the light of the extracted color components is observed by the light receiving element. In addition, light in which a specific color component is extracted from incident light is called "color separation".

Specifically, on the incident light side of the light receiving element, color filters of red (R), green (G), and blue (B), which are the three primary colors of light, are provided. The incident light from the observation object is color-separated by the color filter before reaching the light receiving element to extract specific light. The extracted light reaches the light receiving element facing each color filter, and is photoelectrically converted into an electric signal. In this way, output values (usually voltage values) of the three primary colors of light in the incident light are obtained. Furthermore, by combining the obtained output values, it is possible to reproduce the observed object as a color image.

In addition, the general color filter is patterned and exposed on the photosensitive resin by "photolithography" and then developed with a developer, so that the pattern becomes the desired pattern. In addition, there are a stepper, an alignment exposure machine, a mirror projection alignment exposure machine, and the like in the exposure machine using the photolithography method. When high pixelation and miniaturization are required, a stepper is used.

However, in such an imaging element, the demand for increasing the number of pixels has increased in recent years, and the miniaturization of pixels has been progressing. Specifically, the pixel pitch exceeds 3 μm and becomes about 2 μm. If it becomes a fine pixel with a pixel pitch of about 2 μm, the area per pixel becomes small. Therefore, the amount of light incident on the light receiving element decreases. As a result, the sensitivity of the imaging element decreases, and the image quality may decrease (a dark image may be obtained).

As described above, in the conventional imaging device, in order to color-separate the light from the observation object, the color filters of the three primary colors of blue, green and red are arranged on the incident light side of the light receiving device. An example of the spectral transmittance of such color filters of the three primary colors of blue, green, and red is shown in FIG. 1 . In FIG. 1 , the horizontal axis represents wavelength, and the vertical axis represents transmittance. As shown in FIG. 1 , the apexes of the blue and green transmittances have a value of about 80%. That is, since the blue and green color filters have low transmittance, the amount of light reaching the light receiving element decreases. As a result, image quality deteriorates (dark image).

Furthermore, light-receiving elements such as CMOS and CCD have a wide sensitivity region in which the wavelength of light is about 400 nm to 1000 nm. In particular, as shown in Figure 2, the SPD (Silicon Photo Diode, photodiode) sensitivity of the light receiving element shows a high value in the wavelength region around 700nm. That is, it has high sensitivity near the red wavelength region (700nm). However, the sensitivity decreases as it goes to the short wavelength region, and becomes about half of the sensitivity of red near the blue wavelength region (400nm to 500nm).

As can be seen from the above description, in an imaging element having color filters for the three primary colors of blue, green, and red, the sensitivity of the light receiving element is low in the blue region. In addition, the transmittance of the blue color filter is lower than that of the red and green color filters.

Therefore, in the conventional imaging device, blue has poor reproducibility and color expression compared with red and green, and there is a problem that it cannot reproduce a strict color balance.

For this problem, in order to cope with the reduction of the light quantity of the light receiving element, a technique of using a complementary color filter composed of cyan (C), magenta (M), and yellow (Y) has been proposed (for example, refer to Japanese Patent Laid-Open No. 2002-51350 Bulletin).

In this technology, synthetic light of red (R) and green (G) can be extracted by using a yellow (Y) color filter. Also, by using a magenta (M) color filter, synthetic light of red (R) and blue (B) can be extracted. Also, by using a cyan (C) color filter, synthetic light of green (G) and blue (B) can be extracted. That is, since two colors of light are transmitted through the color filter of the complementary color system, the transmittance of light can be increased. Accordingly, it is possible to suppress a decrease in the light quantity of incident light entering the imaging element.

However, complex calculations are required to extract light of three primary colors of blue, green, and red from light transmitted through complementary color filters of cyan, magenta, and yellow.

For example, according to the observed value of each filter, blue=(cyan+magenta-yellow)/2, green=(cyan+yellow-magenta)/2, red=(magenta+yellow-cyan)/ 2 etc. calculations.

FIG. 3 is a graph showing the spectral characteristics of common C, M, and Y complementary color filters. As described above, in the color filter of the complementary color system, observation values corresponding to the three primary colors are obtained by calculation. However, as shown in FIG. 3 , each filter of the complementary color system also transmits light in a wavelength region of light that should be shielded. Furthermore, as shown by u1, u2, and u3 in FIG. 3, each filter of the complementary color system has a variation in transmittance in the wavelength region to be shielded for each color. Due to this variation, a noise component is included in the value of the calculation result.

Therefore, in an imaging device using a complementary color filter, although the sensitivity is high, noise increases, and there is a problem that color reproducibility (color separation) is lowered compared with a color filter of three primary colors.

Contents of the invention

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an imaging device having excellent color balance and color reproducibility.

In order to solve the above-mentioned problems, the present invention provides an imaging element, comprising: a filter for extracting a specific color component in incident light; a light-receiving element for observing the incident light through the filter; the filter includes a transparent filter, a yellow filter for extracting yellow components, and a red filter for extracting red components.

Description of drawings

FIG. 1 is a graph showing an example of the spectral transmittance of a conventional imaging element.

FIG. 2 is a graph showing the relationship between human visual sensitivity, sensitivity of a light receiving element (SPD sensitivity), and wavelength and transmittance of an ideal infrared cut filter.

FIG. 3 is a graph showing spectral characteristics of color filters of general C, M, and Y complementary color systems.

FIG. 4 is a plan view showing an example of an array state of filters of the imaging element 1 according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view showing an example of the imaging element 1 according to this embodiment.

FIG. 6 is a graph showing an example of the spectral transmittance of the transparent filter 2W, the yellow filter 2Y, and the red filter 2R according to this embodiment.

FIG. 7 is a graph showing an example of the apparent spectral transmittances of the blue filter, green filter, and red filter obtained by calculation of the imaging element 1 according to the embodiment.

FIG. 8 is a graph showing an example of the spectral characteristics of a conventional imaging element.

FIG. 9 is a cross-sectional view showing an example of the imaging element 9 according to the second embodiment of the present invention.

FIG. 10 is a cross-sectional view showing an example of the imaging element 11 according to the third embodiment of the present invention.

FIG. 11 is a diagram for explaining the manufacturing process of the imaging element 11 according to this embodiment.

FIG. 12 is a diagram for explaining the manufacturing process of the imaging element 11 according to this embodiment.

FIG. 13 is a diagram for explaining the manufacturing process of the imaging element 11 according to this embodiment.

FIG. 14 is a diagram for explaining the manufacturing process of the imaging element 11 according to this embodiment.

FIG. 15 is a diagram for explaining the manufacturing process of the imaging element 11 according to this embodiment.

FIG. 16 is a plan view showing an example of the arrangement of the light shielding film 19 of the imaging element 17 according to the fourth embodiment of the present invention.

FIG. 17 is a front view showing an example of an arrangement state of filters of the imaging element 31 according to the fifth embodiment of the present invention.

FIG. 18 is a cross-sectional view showing an example of the imaging element 31 according to this embodiment.

FIG. 19 is a diagram showing another example of the imaging element 31 according to this embodiment.

FIG. 20 is a diagram showing an example of the spectral transmittance of the compensation filter 2Blk, the clear filter 2W, the yellow filter 2Y, and the red filter 2R according to this embodiment.

FIG. 21 is a diagram showing an example of the apparent spectral transmittances of the blue filter, green filter, and red filter obtained by calculation of the imaging element 31 according to this embodiment.

FIG. 22 is a graph showing the spectral characteristics of the compensation filter according to this embodiment.

FIG. 23 is a graph showing spectral characteristics of a general absorption type infrared cut filter.

FIG. 24 is a cross-sectional view showing an example of the imaging element 39 according to the sixth embodiment of the present invention.

FIG. 25 is a cross-sectional view showing an example of the imaging element 41 according to the seventh embodiment of the present invention.

FIG. 26 is a front view showing a first example of the arrangement of the light-shielding film 19 of the imaging element 47 according to the eighth embodiment of the present invention.

FIG. 27 is a cross-sectional view showing the imaging element 47 according to this embodiment.

FIG. 28 is a cross-sectional view showing a second example of the arrangement of the light-shielding film 19 of the imaging element 44 according to this embodiment.

29 is a graph showing spectral transmittance characteristics of a compensation filter according to a ninth embodiment of the present invention.

FIG. 30 is a graph showing the spectral transmittance characteristics of the compensation filter according to this embodiment.

FIG. 31 is a graph showing spectral characteristics of a compensation filter according to a tenth embodiment of the present invention.

FIG. 32 is a schematic diagram showing the configuration of an imaging element according to an eleventh embodiment of the present invention.

FIG. 33 is a diagram showing a concept of an arrangement state of the color filters in the imaging unit 110 according to this embodiment viewed from the incident light side.

FIG. 34A is a diagram showing an example of a cross section of the imaging unit 110 according to this embodiment.

FIG. 34B is a diagram showing an example of a cross section of the imaging unit 110 according to this embodiment.

FIG. 35 is a diagram for explaining the operation of the imaging element according to this embodiment.

Fig. 36 is a graph showing stimulation values of human eyes by changes in light wavelength.

FIG. 37A is a diagram illustrating a method of manufacturing the imaging unit 110 according to the twelfth embodiment of the present invention.

FIG. 37B is a diagram for explaining a method of manufacturing the imaging unit 110 .

FIG. 37C is a diagram for explaining a method of manufacturing the imaging unit 110 .

FIG. 37D is a diagram for explaining a method of manufacturing the imaging unit 110 .

FIG. 38A is a diagram for explaining a method of manufacturing the imaging unit 110 .

FIG. 38B is a diagram for explaining a method of manufacturing the imaging unit 110 .

FIG. 38C is a diagram for explaining a method of manufacturing the imaging unit 110 .

FIG. 38D is a diagram for explaining a method of manufacturing the imaging unit 110 .

FIG. 38E is a diagram for explaining a method of manufacturing the imaging unit 110 .

FIG. 39 is a diagram showing another example of the imaging element according to this embodiment.

FIG. 40 is a diagram showing another example of the imaging element according to this embodiment.

FIG. 41 is a schematic diagram showing the configuration of an imaging device according to a thirteenth embodiment of the present invention.

FIG. 42 is a conceptual view of the arrangement state of the color filters 114 in the imaging unit 110T according to this embodiment viewed from the incident light side.

FIG. 43A is a cross-sectional view showing an example of an imaging unit 110T according to this embodiment.

FIG. 43B is a cross-sectional view showing an example of an imaging unit 110T according to this embodiment.

FIG. 44 is a diagram showing another example of the imaging unit 110T according to this embodiment.

FIG. 45 is a graph showing the relationship between human visual sensitivity, sensitivity of a light receiving element (SPD sensitivity), and wavelength and transmittance of an ideal infrared cut filter.

46 is a graph showing the relationship between the wavelength of light and the transmittance in a reflective infrared cut filter and an absorptive infrared cut filter.

Fig. 47 is a graph showing the spectral characteristics of the planarization layer according to the first embodiment of the present invention.

FIG. 48 is a diagram showing spectral characteristics of the transparent filter 114W, the yellow filter 114Y, the red filter 114R, and the compensation filter 114Blk according to the first embodiment.

Fig. 49 is a graph showing the spectral characteristics of the apparent blue filter, green filter, and red filter obtained by computation of the imaging element according to the first embodiment.

Fig. 50 is a graph showing the spectral characteristics of a transparent resin according to the second embodiment of the present invention.

FIG. 51 is a diagram showing the spectral characteristics of the transparent filter 114W, the yellow filter 114Y, the red filter 114R, and the compensation filter 114Blk according to the second embodiment.

Fig. 52 is a graph showing the spectral characteristics of the apparent blue filter, green filter, and red filter obtained by computation of the imaging element according to the second embodiment.

FIG. 53 is a diagram showing an example of the spectral characteristics of the filters F1 to F7 according to the fourteenth embodiment of the present invention.

FIG. 54 is a diagram for explaining the concept of an external color filter according to this embodiment.

FIG. 55 is a front view showing an example of an imaging element according to a fifteenth embodiment of the present invention.

FIG. 56 is a diagram showing an example of the spectral characteristics of the filters F1 to F7 according to this embodiment.

Detailed ways

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in the following description, the same code|symbol is attached|subjected to the same element, and the description is abbreviate|omitted.

<First Embodiment>

In this embodiment, an imaging element that provides a filter layer on the light incident side of a light receiving element such as a CMOS or a CCD, and observes a color component of an observation object will be described.

FIG. 4 is a plan view showing an example of an arrangement state of filters of the imaging element according to the present embodiment. An example of the state of the filter viewed from the light incident side is shown in FIG. 4 .

FIG. 5 is a cross-sectional view showing an example of an imaging element according to this embodiment. FIG. 5 shows the II' section of FIG. 4 . In addition, in FIG. 5 , the case where the light receiving element is a CMOS is illustrated as an example, but the same applies to the case where the light receiving element is a CCD. Hereinafter, the same structure applies to other cross-sectional views of the imaging device.

The imaging device 1 includes a filter layer 2 for extracting a specific color component in incident light, a light receiving element 3 for observing incident light through the filter layer 2 , and a computing unit 4 .

The filter layer 2 includes a transparent filter 2W, a yellow filter 2Y, and a red filter 2R. One unit of color separation is formed by making the yellow filter 2Y two pixels, and making the transparent filter 2W and the red filter 2R each one pixel, a total of four pixels. That is, the ratio of the number of pixels of the yellow filter 2Y is equal to the ratio of the total number of pixels of the transparent filter 2W and the red filter 2R. Thereby, the arithmetic processing of {(white)-(yellow)} and {(yellow)-(red)} which will be described later can be executed on a unit-by-unit basis.

The transparent filter 2W, the yellow filter 2Y, and the red filter 2R are adjacently arranged in a lattice to form a surface.

The transparent filter 2W preferably does not mainly absorb long-wavelength light of 400 nm or more but transmits it. That is, the transparent filter 2W transmits light composed of blue components, green components, and red components. For example, the transparent filter 2W is preferably a filter having a transmittance of 95% or higher for light having a wavelength of 400 nm or longer based on transparent glass having a refractive index n of about 1.5. Such a transparent filter 2W is formed of resins such as phenol, polyethylene, and acrylic, but from the viewpoint of heat resistance and the like, it is preferably formed of polyethylene, more preferably acrylic.

The yellow filter 2Y is a filter for extracting a yellow component (light composed of a red component and a green component) in incident light. The yellow filter 2Y is a filter of a complementary color system. Generally, the light transmittance of the color filter of the complementary color system is higher than that of the color filter of the three primary color systems of blue, green and red.

The red filter 2R is a red color filter for extracting a red component in incident light. Generally, the transmittance of a red color filter is higher than that of a blue filter and a green filter which are other color filters of the three primary color systems.

The light receiving element 3 is arranged on the opposite side to the light incident side of the filter layer 2 , and includes an incident light receiving element 3W, a yellow light receiving element 3Y, and a red light receiving element 3R. In addition, the light receiving element 3 has a function of receiving light passing through the filter layer 2, converting the received light into an electrical signal, and obtaining an observed value (intensity value). In addition, a one-to-one combination of a light receiving element and a filter corresponds to a pixel. In addition, the light receiving element 3 is formed on the light incident side of the semiconductor substrate 5 .

The incident light receiving element 3W corresponds to the transparent filter 2W, and the incident light is observed through the transparent filter 2W.

The yellow light receiving element 3Y corresponds to the yellow filter 2Y, and the incident light is observed through the yellow filter 2Y.

The red light receiving element 3R corresponds to the red filter 2R, and observes incident light through the red filter 2R.

The computing unit 4 includes a blue computing unit 4B, a green computing unit 4G, and a red computing unit 4R. The computing unit 4 has a function of calculating the blue observed value Db and the green observed value Dg from the observed values Dw, Dy of the incident light receiving element 3W, the yellow light receiving element 3Y, and the red light receiving element 3R.

The blue calculation unit 4B subtracts the observed value Dy observed by the yellow light receiving element 3Y from the observed value Dw observed by the incident light receiving element 3W to obtain the observed value Db of blue (=Dw−Dy).

The green calculation unit 4G subtracts the observed value Dr observed by the red light receiving element 3R from the observed value Dy observed by the yellow light receiving element 3Y to obtain a green observed value Dg (=Dy−Dr).

That is, if the colors corresponding to the transparent filter 2W, the yellow filter 2Y, and the red filter 2R are respectively white (W), yellow (Y), and red (R), then the following (1) formula and The relationship of (2) is established.

Blue (B) = white (W) - yellow (Y) ... (1)

Green (G) = yellow (Y) - red (R) ... (2)

In FIG. 5 , a cross section of the yellow filter 2Y and the transparent filter 2W, and of the yellow light receiving element 3Y and the incident light receiving element 3W is shown. In addition, the cross-section of other filters and other light-receiving elements has the same structure.

The light receiving element 3 is formed on the light incident side of the semiconductor substrate 5 .

A planarization layer 6 is stacked on the light incident side surface of the semiconductor substrate 5 on which the light receiving element 3 is formed. Thereby, the filter layer 2 can be formed as a flat installation surface. As the material of the planarization layer 6, one or more kinds of resins containing acrylic or epoxy, polyimide, urethane, melamine, polyester, urea, styrene, etc. can be used. resin.

On the light incident side of the planarizing layer 6 , the filter layer 2 corresponding to the light receiving element 3 is formed, and on the light incident side of the filter layer 2 , a resin layer (transparent planarizing layer) 7 is laminated.

On the light incident side of the resin layer 7 , a microlens 8 corresponding to the light receiving element 3 is provided.

The microlens 8 is arranged above each of the transparent filter 2W, the yellow filter 2Y, and the red filter 2R so as to form a pair with each of the transparent filter 2W, the yellow filter 2Y, and the red filter 2R. In addition, the microlens 8 is formed of acrylic resin or the like, and enhances light-condensing properties of the incident light on the light-receiving element 3W, the yellow light-receiving element 3Y, and the red light-receiving element 3R.

In addition, in this embodiment, the film thickness of each filter layer 2 is 1.4 μm, and the pixel pitch (the pitch between the transparent filter 2W, the yellow filter 2Y, and the red filter 2R) is 2.6 μm.

An ultraviolet absorber is added to the above-mentioned planarization layer 6 . Specifically, the planarization layer 6 is formed of a thermosetting acrylic resin to which an ultraviolet absorber is added, and has a film thickness of 0.3 μm. The purpose of adding the ultraviolet absorber to the planarization layer 6 is to prevent halation of exposure light from the pattern of the base semiconductor substrate 5 when the filter layer 2 is formed by photolithography, and to form a filter with good shape. In addition, here, pattern exposure, development, etc. are performed on the photosensitive resin layer by the photolithography method, and the photosensitive resin is left in a predetermined part.

In addition, in this embodiment, the planarization layer 6 is formed, but the planarization layer 6 may be omitted for the purpose of further reducing the thickness of the imaging element.

In addition, in the present embodiment, the transparent filter 2W is formed of an alkali-soluble photosensitive acrylic resin (refractive index n=1.55).

In addition, the yellow filter 2Y and the red filter 2R are formed by adding a predetermined organic pigment to the transparent resin (photosensitive acrylic resin) used in the formation of the transparent filter 2W. . For example, C.I. Pigment Yellow 150 is mentioned as an organic pigment used for forming the yellow filter 2Y. In addition, a mixture of C.I.Pigment Yellow 150 and C.I.Pigment Yellow 139 can also be used. In addition, examples of organic pigments used in the formation of the red filter 2R include C.I. Pigment Red 177, C.I. Pigment Red 48:1, and a mixture of C.I. Pigment Yellow 139. In addition, the transparent filter 2W may be formed of a transparent resin to which no coloring matter is added.

FIG. 6 is a graph showing an example of the spectral transmittance of the transparent filter 2W, the yellow filter 2Y, and the red filter 2R.

The imaging element 1 performs calculation (subtraction) from the observed values Dw, Dy, and Dr of the light receiving elements to obtain the observed values Db, Dg, Dr of the three primary colors of blue, green, and red. That is, by performing such calculations, the imaging device 1 can be considered to have (virtually) a blue filter and a green filter externally.

FIG. 7 is a graph showing an example of the spectral transmittance of the apparent blue filter, green filter, and red filter obtained by calculation of the imaging device 1 . If the spectral transmittance of the blue filter and the green filter on the appearance of the imaging element 1 shown in FIG. 7 is compared with the spectral transmittance of the conventional blue and green color filters shown in FIG. 1, the imaging element The transmittance of the blue filter and green filter on the surface of 1 is higher than the transmittance of conventional blue and green filters. In particular, the transmittance of the blue filter on the outside is higher than that of conventional blue filters. Therefore, the imaging element 1 according to the present embodiment has high blue sensitivity and good color balance.

Furthermore, a comparison between the imaging device 1 according to the present embodiment and a conventional imaging device will be described below.

First, the "color filter on the appearance" will be described.

FIG. 8 is a graph showing an example of the spectral characteristics of a conventional imaging element.

The spectral characteristic of a conventional imaging element is considered to be the product of the sensitivity of the light-receiving element (Fig. 8(A)) and the transmittance of the filter placed on the light incident side of the light-receiving element (Fig. The values are equivalent, as shown in Fig. 8(C).

As shown in FIG. 8(B) , the transmittance of the blue color filter in the conventional imaging element is lower than the transmittance of the red and green color filters. In addition, as shown in FIG. 8(A), the sensitivity of the light receiving element in the blue wavelength range is lower than that in the red and green wavelength ranges. Therefore, when the sensitivity ratio is found in the conventional imaging element, (blue/green) is smaller than (red/green). Therefore, color reproducibility becomes low.

On the other hand, the imaging element 1 in this embodiment includes a transparent filter 2W, a yellow filter 2Y, and a red filter 2R instead of the color filters of red, green, and blue as the three primary colors. Therefore, the spectral characteristics of the imaging element 1 in this embodiment are considered to be related to the sensitivity of the light receiving element and the characteristics of the transparent filter 2W, the yellow filter 2Y, and the red filter 2R arranged on the light incident side of the light receiving element. The values of the products of the respective multiplications of the transmittances are equivalent. The transmittance of the transparent filter 2W, the yellow filter 2Y, and the red filter 2R is higher than that of the blue filter and the green filter. Therefore, when the incident light is observed by the incident light receiving element 3W, the yellow light receiving element 3Y, and the red light receiving element 3R through the transparent filter 2W, yellow filter 2Y, and red filter 2R, according to its observed value Dw, The observed values Db and Dg calculated by Dy and Dr can be said to be observation results obtained through high transmittance. In particular, with respect to the observed value Db of blue, the sensitivity ratio (blue/green) can be increased, and the color reproducibility can be improved.

Furthermore, in the present embodiment, the blue observed value Db and the green observed value Dg can be obtained by one subtraction process. Therefore, compared with an imaging element using a conventional color filter of a complementary color system, calculation can be simplified, and vivid colors close to primary colors can be expressed.

Next, "noise due to dark current" will be described.

As shown in FIG. 8(C), the light receiving element generates a weak current even when no light is incident on it. Such a current flowing from the light receiving element despite no light incident is called "dark current" and causes noise. Conventional color filters of the three primary colors of blue, green, and red transmit light in a predetermined wavelength region in terms of spectral characteristics, and there are also wavelength regions that block light.

However, in the light receiving element, dark current also occurs in the wavelength range where light is blocked. Therefore, the observation result of the conventional imaging device includes, in addition to the observation result of light in the wavelength region through which light is transmitted, noise of dark current, which may degrade color reproducibility.

On the other hand, in the imaging element 1 according to this embodiment, as described above, the observed value Dw of the incident light receiving element 3W is subtracted from the observed value Dy of the yellow light receiving element 3Y, and the observed value Dy of the yellow light receiving element 3Y is subtracted from the observed value Dy of the red light receiving element 3Y. Since the observed value Dr of the light receiving element 3R is subtracted, the value of the dark current cancels out. Therefore, noise can be removed from the observation result, and color reproducibility can be improved.

Next, the "floating of the spectrum" will be described.

As shown in FIG. 8(B), among the spectral transmittances of conventional blue, green, and red color filters, the transmittances of the descending sides of the spectral curves of the blue and red color filters are several percentage points lower than those of the green ones. The transmittance of the falling edge of the spectral curve of the color filter is about 10% higher. In this way, the trailing edge height is referred to as the large fluctuation of the spectrum.

In a conventional imaging device, the falling edge of the spectral curve of the green color filter exists in the blue and red wavelength regions. In addition, the spectral fluctuation of the green descending side is large. Therefore, in the observation result of green, blue and red are mixed, and there is a problem that the reproducibility of green is lowered.

On the other hand, in the imaging device 1 according to this embodiment, the observed value Dy of the yellow light receiving element 3Y and the observed value Dr of the red light receiving element 3R are subtracted to obtain the observed value Dg of green. Therefore, spectral fluctuation can be reduced, and color reproducibility can be improved.

Next, the "ultraviolet absorber and infrared absorber" will be described.

Light-receiving elements such as CMOS and CCD have some sensitivity to ultraviolet rays that humans cannot feel. Therefore, the filter layer 2 according to the present embodiment preferably absorbs light of 400 nm or less and does not transmit it, and does not absorb light of a wavelength of 400 nm or more but transmits it. Here, it is preferable to add an ultraviolet absorber or a photoinitiator and a curing agent used for curing the resin to the transparent filter 2W so that the transparent filter 2W has an ultraviolet absorbing function. As the ultraviolet absorber, for example, benzotriazole-based compounds, benzophenone-based compounds, salicylic acid-based compounds, and coumarin-based compounds can be used. In addition, light stabilizers such as hindered amine compounds, quenchers, and the like may be added to the ultraviolet absorber, for example. Furthermore, a functional group having an ultraviolet absorbing function is suspended in a polymer or a monomer of a resin used for forming the transparent filter 2W, or a curing agent, or a group that is incorporated into a polymer is polymerized. . For example, a quinone or anthracene may be introduced into a polymer, and an ultraviolet absorbing group may be added to a monomer. In addition, the term "suspension" refers to being incorporated into the resin molecular chain in the form of a reactive absorbent or the like.

Furthermore, it is preferable to add an infrared absorbing compound or an infrared absorbing agent to the resin constituting the transparent filter 2W. For example, it is added to the resin constituting the transparent filter 2W by suspension.

Furthermore, according to the present embodiment, the filter layer 2 forms color separation by making the yellow filter 2Y into two pixels, and making the transparent filter 2W and the red filter 2R into one pixel, a total of four pixels. one unit. Therefore, when obtaining the blue and green observation values, there is no need to repeatedly use the yellow data value. That is, in the calculation part 4, the calculation processing of {(white)-(yellow)} and {(yellow)-(red)} can be individually performed in one unit. Accordingly, it is possible to increase the speed of calculation processing.

As described above, the imaging element 1 according to the present embodiment can be regarded as an imaging element equipped with a high-transmittance blue filter and a green filter on the outside by a single subtraction process. Compared with components, the observation accuracy of blue has been improved.

<Second embodiment>

In this embodiment, a modified example of the imaging device 1 according to the first embodiment will be described. In addition, the imaging element 9 according to the present embodiment is configured by integrating the transparent filter 2W and the resin layer 7 in the imaging element 1 according to the first embodiment. In addition, the same code|symbol is attached|subjected to the same part as what already demonstrated, and description is abbreviate|omitted.

FIG. 9 is a cross-sectional view showing an example of an imaging element according to this embodiment. Fig. 9 is a view corresponding to the II' section of Fig. 4 . In addition, the transparent filter 10W corresponds to the transparent filter 2W and the resin layer 7 of the first embodiment.

In the imaging element 9 according to the present embodiment, a part of the transparent filter 10W is arranged at the position of the transparent filter 2W according to the first embodiment.

The other part of the transparent filter 10W covers the light incident side surfaces of the yellow filter 2Y and the red filter 2R. That is, the transparent filter 10W has a structure in which the transparent filter 2W according to the first embodiment and the resin layer 7 are integrated, and also functions as a transparent planarizing layer.

Similar to the first embodiment, the imaging element 9 performs calculation (subtraction) from the observed values Dw, Dy, and Dr of the light receiving elements 3 to obtain the observed values Db, Dg for blue and green. That is, the imaging element 9 performs calculations (subtraction) based on the observed values of the light receiving elements 3, and can be considered to be (virtually) equipped with a blue filter, a green filter, and a red filter.

An example of the spectral transmittance of the apparent blue filter, green filter, and red filter at a wavelength of 400 nm to 800 nm obtained by the calculation of the imaging element 9 is shown in the same graph as in FIG. 7 .

As described above, in this embodiment, after the yellow filter 2Y and the red filter 2R are formed, the transparent filter 10W is formed so as to cover each filter. At this time, the transparent filter 10W and the transparent planarizing layer are formed integrally.

That is, by simultaneously performing the steps of forming the transparent filter 10W and the transparent planarizing layer, the patterning step of separately providing the transparent filter is unnecessary, and the manufacturing process of the imaging device 9 can be simplified.

Specifically, in the first embodiment, the portion where the transparent filter 2W is formed is arranged as a part of the transparent filter 10W as a transparent planarization layer, and the transparent filter 10W functions as a transparent planarization layer. Therefore, it is possible to omit the step of separately forming a transparent filter by, for example, photolithography. That is, it is possible to form three-color filters with the labor of forming two-color (yellow and red) filters, and it is possible to reduce the filter forming process by one color.

<third embodiment>

In this embodiment, modified examples of the imaging elements according to the first and second embodiments will be described.

FIG. 10 is a cross-sectional view showing an example of the imaging element according to this embodiment.

The imaging device 11 according to the present embodiment includes a transparent filter 12W having a structure in which the microlens 8 and the transparent filter 10W of the imaging device 9 according to the second embodiment are integrated. The transparent filter 12W also has a function of improving light-condensing properties of incident light to the light-receiving element 3W, the yellow light-receiving element 3Y, and the red light-receiving element 3R.

Hereinafter, the manufacturing process of this imaging element 11 is demonstrated using FIGS. 11-15.

First, a planarizing layer 6 made of a transparent resin is formed on the semiconductor substrate 5 on which the incident light receiving element 3W, the yellow light receiving element 3Y, and the red light receiving element 3R are formed ( FIG. 11 ). Specifically, a coating solution mainly composed of acrylic resin was spin-coated at a rotation speed of 2000 rpm on the semiconductor substrate 5 on which the light-receiving elements were arranged two-dimensionally. Next, a hard film was formed by performing heat treatment at 200° C. to form a planarization layer 6 with a film thickness of 0.2 μm. The coating liquid of the acrylic resin added a coumarin-based ultraviolet absorber at a solid ratio of about 3% was used.

In addition, in forming a color filter made of colored photosensitive resin, ultraviolet rays are used for pattern exposure of the color photosensitive resin. Vignetting sometimes occurs when the pattern is exposed. Therefore, in order to prevent vignetting, it is preferable to add an ultraviolet absorber to the planarization layer 6 . In addition, in order to make the imaging element 11 thinner, the planarization layer 6 may be omitted.

Next, the yellow filter 2Y and the red filter 2R are formed by photolithography ( FIG. 12 ).

Specifically, two color photoresists (yellow and red) mixed with color materials in a photosensitive acrylic resin capable of exposure and development are used to form a yellow filter 2Y and a red filter 2R with a film thickness of about 1 μm, respectively. . In addition, the organic pigment C.I.Pigment Yellow 150 can be used as the color material of the yellow filter 2Y. The solid ratio of the color material (organic pigment) of the yellow filter 2Y is about 33%. In addition, the color material of the red filter 2R can use the mixed pigment of C.I.Pigment Red 177, C.I.Pigment Red 48:1 and C.I.Pigment Yellow 139. The solid ratio of the color material (organic pigment) of the red filter 2R is about 48%.

Next, a transparent resin layer is spin-coated on the semiconductor substrate 5 so as to cover the yellow filter 2Y and the red filter 2R. Next, the transparent resin layer was thermally cured at 180° C. for 3 minutes to form the planarization layer 12 including the transparent filter 12W. The planarization layer 12 is formed using substantially the same material as the planarization layer 6 , and is formed by a coating solution of a thermosetting acrylic resin having a high solid-to-solid ratio for thick film use. In addition, 2% of a coumarin-based ultraviolet absorber was contained in the acrylic resin. In addition, the planarization layer 12 has a film thickness of about 2 μm.

In addition, a photosensitive phenolic resin layer 13 capable of exposure and development is formed on the planarization layer 12 ( FIG. 13 ). In addition, the photosensitive phenolic resin layer 13 is resin which has "heat reflowability". The so-called thermal reflow property refers to the property of melting by heat treatment and being rounded into a lens shape under the action of surface tension.

Next, pattern exposure, development, hard coating, etc. are performed on the photosensitive phenolic resin layer 13 to form a predetermined pattern of photosensitive phenolic resin.

Next, heat treatment at 200° C. is performed to fluidize the photosensitive phenolic resin layer 13 in a predetermined pattern. Thus, a hemispherical lens master mold 13a having a thickness of about 0.6 μm was formed ( FIG. 14 ).

Next, anisotropic dry etching is performed using the lens master 13a as a mask to transfer the shape of the lens master 13a to the planarization layer 12 to form microlenses ( FIG. 15 ). That is, although the lens master mold 13a is eliminated by etching, the lens master mold 13a serves as a mask for the transparent filter 12W, and the hemispherical shape of the lens master mold 13a is transferred to the transparent filter 12W. Thus, the microlens 8 and the transparent filter 12W are simultaneously formed. In addition, the amount of dry etching (etching depth) was about 1 μm. In addition, the yellow filter 2Y and the red filter 2R have a film thickness of 1.2 μm to be etched to the surface.

As described above, it is possible to obtain the imaging element 11 in which a part of the transparent filter 12W functions as a microlens. In addition, since the transparent filter 12W is integrated with the microlens, the imaging element 11 can be made thinner.

In addition, in this embodiment, the transparent filter 12W having the function of the transparent planarizing film is made into the shape of a microlens, but the transparent filter 12W having the function of a planarizing layer may be maintained without forming a microlens. Tablet 12W state. In this case, after the transparent filter 12W is formed in the third step of FIG. 13 , the steps subsequent to the formation of the photosensitive phenolic resin layer 13 are not performed.

In addition, as described above, it is preferable to add an ultraviolet absorber to the flattening layer 6 in order to prevent halation that occurs when the pattern of the color photosensitive resin is exposed.

In addition, it is preferable to add an ultraviolet absorber to the transparent filter 12W in order to prevent the occurrence of noise due to ultraviolet light due to the sensitivity of the light receiving element in the ultraviolet region.

Examples of the ultraviolet absorber include fine particles made of metal oxides such as cerium oxide and titanium oxide. However, as described above, when the lens shape is transferred onto the transparent filter 12W, and the transparent filter 12W becomes a transfer-type microlens, when the ultraviolet absorber is made of a metal oxide layer, the The inorganic material in the resin of the transfer lens becomes an optical foreign matter. Therefore, when the light is blocked, a black portion occurs in an image obtained by the imaging element 11 . Therefore, it is preferable to use a dye-based ultraviolet absorber. For example, as ultraviolet absorbers, benzotriazoles, benzophenones, triazines, salicylates, coumarins, xanthenes, methoxycinnamic acid compounds, and the like can be used.

In addition, in the first to third embodiments, yellow may be used as a base color of other colors other than the transparent part. That is, in addition to the transparent part, yellow may be commonly included in the red part. In this case, for example, while the yellow filter 2Y is formed using a yellow resin, the yellow filter 2Y is also formed at the formation position of the red filter, and then the red filter 2R is formed at the formation position of the red filter. .

<Fourth embodiment>

In this embodiment, an imaging element provided with a light-shielding film (reflection suppression filter) that suppresses reflection, diffusion, and wrap-around of light other than incident light entering the light receiving element will be described.

16 is a plan view showing an example of the arrangement of light-shielding films of the imaging element according to this embodiment. The imaging element 17 shown in FIG. 16 includes a light shielding film 19 for suppressing reflection and transmission of light on the outer peripheral portion of the effective pixel portion 18 provided with the filter layer 2 on the light incident side of the light receiving element. In addition, the imaging element 17 has an electrode portion 20 made of aluminum or the like for electrical connection with the outside. The light shielding film 19 is not formed on the electrode portion 20 .

As the color material of the light-shielding film 19, for example, a resin solution in which an organic pigment (a mixture of C.I. Pigment Violet 23 and C.I. Pigment Red 177, C.I. Pigment Red 48:1, and C.I. Pigment Yellow 139) is dispersed and mixed can be used. When this color material is applied and hardened, a light-shielding film 19 is formed. However, the color material is not limited thereto, and other pigments may also be used. In addition, a single layer may be used, or different colors may be laminated.

If such a light-shielding film 19 is disposed on the outer peripheral portion of the effective pixel portion 18 of the imaging element 17 , it is possible to prevent the observation result of the imaging element 17 from being affected by noise. As a result, image quality can be improved.

In addition, in conventional imaging elements, light incident on parts other than the light receiving element may be scattered inside the imaging element to become stray light. When this stray light enters the light receiving element, it becomes noise. In addition, when unnecessary light enters the peripheral area of the light receiving element, it becomes a cause of noise.

On the other hand, in the imaging element 17 according to the present embodiment, the light-shielding film 19 having a transmission suppressing property in the visible light wavelength region is arranged around the effective opening portion of the light receiving element and a part of the semiconductor substrate 5 (for example, the outer periphery of the semiconductor substrate 5 ). . Therefore, light incident on parts other than the light receiving element is absorbed by the light shielding film 19 . Thereby, unnecessary light, such as stray light, can be prevented from entering a light receiving element. That is, noise can be reduced, and the image quality obtained by the imaging element 17 can be improved.

In addition, in the present embodiment, it is preferable that the light-shielding film 19 has a function of cutting infrared rays in addition to the function of cutting visible light rays. Specifically, the ultraviolet cutoff function is realized by forming the light-shielding film 19 with a film thickness of 0.8 μm using a resin solution in which a black pigment such as carbon black is mixed at a solid ratio of 40%.

Furthermore, an absorbing film that absorbs infrared rays and ultraviolet rays may be laminated on the light-shielding film 19 using a black pigment such as carbon black. Thereby, it is possible to prevent infrared rays and ultraviolet rays incident on portions other than the light-receiving element from being scattered and becoming stray light and generating noise. In addition, if an infrared absorber and an ultraviolet absorber are added to the transparent resin used for forming the microlens 8 as the absorbing film for absorbing infrared rays and ultraviolet rays, material cost can be reduced.

In addition, in this embodiment, the case where the light-shielding film 19 and the absorbing film are provided in the imaging element 1 according to the first embodiment has been described as an example, but the light-shielding film may be provided in the imaging element 1 according to other embodiments. 19 and absorbent film. In addition, only the light-shielding film 19 may be provided in the imaging element. In addition, an ultraviolet absorber or an infrared absorber may be added to the light-shielding film 19 .

<Fifth Embodiment>

In this embodiment, an imaging element 31 in which a compensation filter 2Blk is added to the imaging element 1 according to the first embodiment will be described.

FIG. 17 is a front view showing an example of an arrangement state of filters in the imaging element 31 according to the present embodiment. FIG. 18 is a cross-sectional view showing an example of the imaging element 31 according to this embodiment. FIG. 18 shows a section III-III' in FIG. 17 . In addition, in FIG. 18 , the case where the light receiving element is a CMOS is illustrated as an example, but the same applies to the case where the light receiving element is a CCD. Hereinafter, the same structure applies to other cross-sectional views of the imaging device.

The imaging element 31 according to this embodiment includes a filter layer 2 for extracting a specific color component in incident light, a light receiving element 3 for observing incident light through the filter layer 2 , and a computing unit 4 .

In addition to the transparent filter 2W, the yellow filter 2Y, and the red filter 2R, the filter layer 2 also includes a compensation filter 2Blk. One unit of color separation is formed by combining the transparent filter 2W, the yellow filter 2Y, the red filter 2R, and the compensation filter 2Blk one by one. The transparent filter 2W, the yellow filter 2Y, the red filter 2R, and the compensation filter 2Blk are adjacently arranged in a grid. In addition, the film thickness of each filter is 1.4 μm, and the pixel pitch (the pitch of the transparent filter 2W, the yellow filter 2Y, the red filter 2R, and the compensation filter 2Blk) is 2.6 μm.

The compensation filter 2Blk has transmission suppression characteristics (low transmission characteristics) in the visible light wavelength region, and is a filter having transmission characteristics on the longer wavelength side than the visible light wavelength region. That is, the compensation filter 2Blk has a characteristic that the transmittance in the infrared region is higher than that in the visible light wavelength region. In addition, the compensation filter 2Blk is dark when viewed visually.

In this embodiment, the compensation filter 2Blk is formed by optically overlapping violet (V) and red (R). In addition, as a specific realization method of optical superimposition, one filter may be formed by mixing a purple color material and a red color material, or a purple filter and a red filter may be laminated.

The light receiving element 3 is arranged on the opposite side of the light incident side of the filter layer 2, and includes a compensating light receiving element 3Blk in addition to the incident light receiving element 3W, the yellow light receiving element 3Y, and the red light receiving element 3R. These light receiving elements 3 are formed and arranged on a semiconductor substrate 5 .

The compensation light receiving element 3Blk corresponds to the compensation filter 2Blk, and observes incident light through the compensation filter 2Blk.

The computing unit 4 includes a blue computing unit 4B, a green computing unit 4G, and a red computing unit 4R. Calculator 4 is provided with the observation values Dw, Dy, Dr, and Dblk of incident light receiving element 3W, yellow light receiving element 3Y, red light receiving element 3R, and compensation light receiving element 3Blk to calculate blue observed value Db, green observed value Dg and Function of the observed value HDr of compensated red.

The red calculation unit 4R subtracts the observed value Dblk observed by the compensating light receiving element 3Blk from the observed value Dr observed by the red light receiving element 3R to obtain the compensated red observed value HDr (=Dr−Dblk).

FIG. 18 shows a cross section of the red filter 2R and the compensation filter 2Blk, and a cross section of the red light receiving element 3R and the compensation light receiving element 3Blk. The same configuration applies to cross-sections of other filters and other light-receiving elements.

In addition, in FIG. 18 , a single-layer compensation filter 2Blk in which a red pigment and a purple pigment are mixed into a transparent resin is shown. However, the compensating filter 2Blk is not limited to the structure shown in FIG. 18, as long as it is realized by optical overlapping. The so-called optical overlapping here, as shown in Figure 18, can be realized by a single-layer colored resin mixed with different multi-colored color materials (pigments, pigments), or can be realized by two or more different-colored filters. The layered structure of color chips is realized. For example, as shown in FIG. 19 , a compensation filter 2Blk may be formed by laminating a violet filter 2V and a red filter 2R. In addition, for color and transmittance adjustment, color materials of two or more colors may be used.

When color filters of two or more colors are optically overlapped, the transmittance of the compensation filter 2Blk is the product of the transmittances of the overlapped color filters. Therefore, by forming the compensating filter 2Blk by optical superimposition, it is possible to fabricate the compensating filter 2Blk having suppressed transmission characteristics in the visible wavelength region and transmissive characteristics on the long wavelength side longer than the visible wavelength region.

As organic pigments used in the formation of the compensation filter 2Blk, for example C.I.Pigment Violet 23 and organic pigments for the red filter 2R (such as C.I.Pigment Red 177, C.I.Pigment Red 48:1 and C.I.Pigment Yellow 139 mix) mix.

An example of the spectral transmittance of the compensating filter 2Blk formed in this way, the transparent filter 2W, the yellow filter 2Y, and the red filter 2R is shown in FIG. 20 .

As described above, the imaging element 31 performs calculation (subtraction) from the observed values Dw, Dy, Dr, and Dblk of the light receiving elements to obtain the observed values Db, Dg, and HDr of the three primary colors of blue, green, and compensated red. In other words, the imaging element 31 can be considered (virtually) to be equipped with blue filters, green filters, and red filters by performing arithmetic processing.

FIG. 21 is a graph showing an example of the spectral transmittance of the apparent blue filter, green filter, and red filter obtained by the calculation of the imaging element 31 . If the spectral transmittance of the blue filter, green filter, and red filter on the appearance of the imaging element 31 shown in FIG. 21 is compared with the spectral transmittance of the conventional blue, green, and red filters shown in FIG. The transmittance is characterized in that the transmittance of the blue filter, green filter, and red filter on the surface of the imaging element 31 is higher than that of conventional blue and green color filters. In particular, the transmittance of the blue filter on the outside is higher than that of conventional blue filters in the blue wavelength region. Therefore, in the imaging element 31 according to this embodiment, the sensitivity to blue is high, and the color balance is improved.

In addition, the blue observed value Db, the green observed value Dg, and the compensated red observed value HDr obtained by the imaging element 31 are calculated by subtracting the observed values in the infrared region, respectively. Therefore, the curves of the spectral transmittances of the blue filter, green filter, and red filter on the surface become suppressed (cutoff) in the curves of the spectral transmittances of the conventional blue, green, and red color filters. ) shows the state of the infrared region. Therefore, in the imaging element 31 according to this embodiment, the infrared cut filter can be omitted, and the thickness can be reduced. In addition, since it is possible to prevent the reduction in red sensitivity that occurs when an absorbing infrared cut filter is provided, it is possible to improve red color reproducibility compared with conventional imaging elements.

In addition, the same discussion as that of the first embodiment applies to "color filter on appearance", "noise due to dark current", "spectral fluctuation", "ultraviolet absorber and infrared absorber".

Hereinafter, the "spectral characteristics of compensation filter 2Blk" will be supplemented.

22 is a graph showing the spectral characteristics of the compensation filter 2Blk formed by mixing and dispersing a violet pigment (for example, C.I. Pigment Violet 23) and a red filter 2R pigment with an acrylic resin film with a film thickness of 1.4 μm.

The transmittance of the compensation filter 2Blk is substantially the same level (same or similar) as the transmittance of the red filter 2R of FIG. 20 on the longer wavelength side than the visible light wavelength region.

By subtracting the observed value Dblk observed by the compensation light receiving element 3Blk from the observed value Dr observed by the red light receiving element 3R, the observation result in the infrared region can be deleted from the observed value Dr observed by the red light receiving element 3R. In other words, the compensation filter 2Blk functions as an infrared cut filter for the observed value of red.

The compensation filter 2Blk shown in FIG. 22 is different from the general absorbing infrared cut filter shown in FIG. 23 in that the transmittance around 600 nm to 650 nm (actual transmittance as an infrared cut filter) is low. . Therefore, it is possible to further improve the color expression of red obtained after the calculation (subtraction).

In this embodiment, the transmittance of the compensating filter 2B1k is within 5% of the transmittance of the red filter shown in FIG. . As a result, it is possible to obtain a compensated observed value HDr of red that is not affected by infrared rays and other colors, thereby improving the color reproducibility of red. Specifically, as shown in FIG. 22 , the transmittance of the compensation filter 2Blk maintains a low value at about 400nm to 630nm, then rises sharply between 630nm and 750nm, and maintains a high value beyond 750nm.

In addition, in a general absorption type infrared cut filter, the wavelength at which the transmittance becomes half (50%) is around 630 nm. In a general infrared cut filter of an inorganic multilayer film, the wavelength at which the transmittance becomes half is about 750 nm. In the compensation filter 2Blk formed by the optical superposition of violet and red, the wavelength at which the transmittance becomes half is between approximately 650 nm and 660 nm. In the compensation filter 2Blk formed by the optical superposition of cyan and red, the wavelength at which the transmittance becomes half is about 740 nm to 750 nm.

From the above point of view, it is preferable that the wavelength of point P at which the transmission value is half is included in the wavelength region between 630nm and 750nm in the compensation filter 2Blk from the viewpoint of improving the accuracy of the observed value of red. In addition, it is preferable to add an ultraviolet absorber to the transparent filter 2W.

In the imaging element 31 according to the present embodiment, the observed value of red HDr after compensation is calculated from the difference between the observed value Dr of red and the observed value Dblk for compensation. Therefore, by setting the compensation filter 2Blk as shown in FIG. 22 , it is possible to prevent the red observed value HDr after compensation from being affected by infrared rays and other colored lights. In addition, it is possible to obtain the imaging element 31 with high red sensitivity and good red color reproducibility.

In addition, in the present embodiment, as described above, the compensation filter 2Blk may be constituted by, for example, an optical superposition of two colors of purple and red, or may be constituted by an optical superposition of two colors of cyan and red. By combining such two colors to form the compensation filter 2Blk, the wavelength position at which the light transmittance of the compensation filter 2Blk becomes half can be adjusted by the ratio of the color materials, and the observed value HDr of red after compensation can be adjusted. adjust.

In addition, the color adjustment in the visible light wavelength region of the compensation filter 2Blk (for example, the adjustment of the gradation), or the rise of the transmittance curve of the compensation filter 2Blk in the near-infrared transmission spectrum at or above 700nm, or the transmittance The adjustment of the half-wavelength position can also be adjusted by adding other color materials or organic pigments of other colors, such as organic pigments such as purple, blue, and green.

In addition, in the imaging device 31 according to the present embodiment, observation results of light in the infrared region that is not the visible region of humans can be deleted, and imaging results close to human vision can be obtained.

In addition, in the imaging element 31 according to this embodiment, unlike the case of using a general absorption type infrared cut filter having the transmission characteristic shown in FIG. . Therefore, red color expression can be improved.

That is, in the imaging element 31 according to this embodiment, it can be regarded as an imaging element equipped with high-transmittance blue, green, and red filters. Observation accuracy.

In addition, in this embodiment, the infrared light absorption function is realized by observing the light in the infrared region with the compensation pixel of the imaging element, and subtracting the observation result of the correction pixel from the observation result of the red pixel. In addition, for other colors (blue, green), observation results obtained by subtracting the infrared region can also be obtained. As a result, the infrared-absorbing infrared cut filter provided in the optical system of the conventional camera module can be omitted, and the camera can be made thinner.

In addition, in this embodiment, yellow can also be used as the base color of other colors than the transparent part. That is, in addition to the transparent part, yellow may also be included in the red part and the compensation color part. In this case, for example, the yellow filter 2Y is formed using yellow resin, and the yellow filter 2Y is also formed at the formation position of the red filter and the formation position of the compensation filter. Then a red filter 2R is formed at the formation position of the red filter, and a compensation filter 2Blk is formed at the formation position of the compensation filter.

<Sixth embodiment>

The imaging element 39 according to the present embodiment is formed by integrally forming the transparent filter 2W and the resin layer 7 in the imaging element 31 according to the fifth embodiment, thereby forming the transparent filter 10W. That is, it corresponds to the configuration in which the compensation filter 2Blk is formed in the imaging element 9 according to the second embodiment. A cross-sectional view of the imaging element 39 is shown in FIG. 24 . Fig. 24 corresponds to the section III-III' of Fig. 17 .

As described above, in the imaging element 39 according to the present embodiment, the steps of forming the transparent filter 10W and the transparent smoothing layer are integrated. Therefore, in the formation of the optical filter, it is not necessary to separately provide a patterning process of the transparent optical filter, and the manufacturing process can be simplified. That is, four-color color filters can be formed by the labor of forming three-color color filters, and the color filter forming process can be reduced by one color.

<Seventh embodiment>

In the imaging device 41 according to the present embodiment, in the imaging device according to the sixth embodiment, the transparent filter 10W is integrally formed with the microlens 8 to form the transparent filter 12W. That is, it corresponds to forming the compensation filter 2Blk in the imaging element 11 according to the third embodiment. A cross-sectional view of the imaging element 41 is shown in FIG. 25 . Fig. 25 corresponds to the section III-III' of Fig. 17 .

As described above, in the present embodiment, since the transparent filter 10W and the microlens 8 are integrally formed, the imaging element 41 can be made thinner.

<Eighth embodiment>

In this embodiment, as in the imaging element according to the fourth embodiment, a light-shielding film is provided in a region other than the region where incident light enters.

FIG. 26 is a front view showing a first example of the arrangement of the light-shielding film 19 of the imaging element 47 according to the present embodiment. Fig. 27 shows a section IV-IV' of Fig. 26 .

The compensation filter 2Blk described in the fifth embodiment can be used for the light shielding film 19 . By using the compensation filter 2Blk for the light-shielding film 19 , it is possible to cut off light in the visible wavelength region, and reduce stray light from the frame portion (peripheral portion) of the imaging element 47 .

In addition, the light-shielding film 19 may also have a function of cutting infrared rays in addition to the function of cutting visible rays. Such a light-shielding film that cuts off visible rays and infrared rays can be realized by forming a film thickness of 0.8 μm using, for example, a resin solution in which a pigment such as carbon black is mixed at a solid ratio of 40%.

FIG. 28 is a cross-sectional view showing a second example of the arrangement of the light-shielding film of the imaging element 44 according to this embodiment.

The imaging element 44 is characterized in that a light-shielding film 15 and a film 16 are laminated on the outer peripheral portion of the CMOS light receiving element 3 .

As the light shielding film 15, for example, a compensation filter 2Blk can be used. That is, the light-shielding film 15 can be formed by the same method as that of the compensation filter 2Blk, using the same material and structure as the compensation filter 2Blk. In addition, the film 16 is a film having at least one of an infrared absorption function and an ultraviolet absorption function.

As described above, in the imaging elements 44 and 47 according to this embodiment, the light-shielding elements having transmission suppression characteristics in the visible light wavelength region are arranged around the effective aperture of the light receiving element or on a part of the semiconductor substrate 5 (for example, the outer periphery of the semiconductor substrate 5 ). membrane. Therefore, light incident on parts other than the light receiving element is absorbed by the light-shielding film. Thereby, unnecessary light, such as stray light, can be prevented from entering a light receiving element. That is, noise can be reduced, and the image quality obtained by the imaging element can be improved.

In addition, in this embodiment, the light-shielding film is disposed on the outer peripheral portion of the effective pixel portion, but when the light-receiving element is a CCD, the light-shielding film may be formed on the wiring portion.

<Ninth embodiment>

This embodiment shows a specific example of the compensation filter 2Blk according to the fifth embodiment.

The compensation filter 2Blk according to this embodiment has a transmittance of 5% or less with respect to light having a wavelength of 400 nm to 550 nm, and the wavelength range of 50% transmittance in the spectral transmittance characteristic is 620 nm to 690 nm. In addition, the transmittance for light having a wavelength of 700 nm is 70%.

In general absorption type infrared cut filters, light absorption begins around 550nm. Therefore, in the present embodiment, 550 nm is considered as the shortest wavelength of light as the increase in the transmission region of the compensation filter 2Blk as a mechanism for performing infrared cutoff. Therefore, the range of low transmittance (transmittance 5% or less) of the compensation filter 2Blk is set to 400 nm to 700 nm.

The compensation filter 2Blk according to the present embodiment has a transmission characteristic in the red region and the near-infrared region with a wavelength of 550 nm or more in order to perform arithmetic processing for realizing the infrared cut function. Here, the stimulus value of the isochromaticity function of the RGB colorimetric system calculated on the premise of human visual acuity has a shape that peaks around 600 nm and falls toward 700 nm. Therefore, it is preferable that the spectral transmittance characteristic of the compensation filter 2Blk is such that it rises from around 600 nm and becomes high transmittance from around 700 nm. Therefore, in the spectral transmittance characteristic, the wavelength range (half-value range) in which the transmittance becomes 50% is preferably 620 nm to 690 nm.

The compensation filter 2Blk has a transmission suppression characteristic (low transmission characteristic) in the visible light wavelength region, and looks black (Black) visually.

In this embodiment, the compensation filter 2Blk is formed of a colored resin composition containing at least each pigment of C.I. Pigment Violet 23 and C.I. Pigment Yellow 139. In addition, it is formed from a colored resin composition containing at least each pigment of C.I.Pigment Violet 23, C.I.Pigment Yellow 139, and C.I.Pigment Red 254.

In this embodiment, the film thickness of each filter is 1.0 μm ~ 1.1 μm, and the pixel pitch (the distance between the transparent filter 2W, the yellow filter 2Y, the red filter 2R, and the compensation filter 2Blk) is 2.6 μm.

The coloring resin composition for compensation filters used in forming the compensation filter 2Blk used the following three types of pigments.

C.I. (Color Index) Pigment Red 254 (hereinafter also abbreviated as R254),

C.I.Pigment Yellow 139 (hereinafter referred to as Y139 for short),

C.I.Pigment Violet 23 (hereinafter referred to as V23 for short).

In addition, R254 can be removed from these 3 pigments. In addition, in addition to these three types of pigments, trace amounts of other types of pigments may be added for color (transmission wavelength) adjustment.

The weight ratios (%) of these three kinds of pigments (R255, Y139, V23) relative to the colored resin composition for compensation filters are respectively, R254 = 0-15%, Y139 = 30-40%, V23 = 55-65% %.

Moreover, the colored resin composition for compensation filters contains resin and a solution other than each pigment as mentioned above. For example, in order to disperse a pigment monomer such as Y139, the following substances are contained in 7 parts (by weight) of Y139.

Acrylic resin solution (solid content 20%): 40 parts,

Dispersant: 0.5 parts,

Cyclohexanone: 23.0 parts.

In addition, the same solution was also used and dispersed in the pigment of V23 and the pigment of R254.

Next, a method of manufacturing the compensation filter 2Blk according to this embodiment will be described.

The above-mentioned two kinds of pigment pastes of Y139 and V23 are prepared according to the respective weights of the above-mentioned weight ratios. and, will

Y139: 14.70 copies,

V23: 20.60 copies,

Acrylic resin solution: 14.00 parts,

Acrylic monomer: 4.15 parts,

Initiator: 0.7 parts,

Sensitizer: 0.4 parts,

Cyclohexanone: 27.00 parts,

PGMAC: 10.89 parts were mixed to form a colored resin composition for compensation filters.

Next, the coloring resin composition coating film for this compensation filter was formed with the spin coater so that the dry film thickness might be 1.1 micrometers.

Next, drying was performed at 70° C. for 1 minute on a hot plate. Next, exposure was performed through a mask capable of forming a 5 μm pixel pattern using an i-line stepper exposure device. In addition, the exposure sensitivity was 1000 mj/cm ² .

Next, image development was performed for 60 seconds by a shower system using an organic alkaline aqueous solution while rotating the semiconductor substrate 5 . After sufficient rinsing with pure water, the water is spin-dried to dry.

Next, heat treatment was performed at 220° C. for 6 minutes on a hot plate to harden the pixel pattern. Thus, a compensation filter having a thickness of 1.1 μm was formed.

Moreover, the carrier which fixes each pigment contained in each colored resin composition for optical filters consists of a transparent resin, its precursor, or their mixture like the above-mentioned acrylic resin.

The transparent resin is a resin having a transmittance of 80% or more in the entire wavelength range of 400 nm to 700 nm which is a visible light region, and more preferably a resin having a transmittance of 90% or more.

Among the transparent resins, thermoplastic resins, thermosetting resins, and active energy ray-curable resins are included. In addition, its precursor includes a monomer or an oligomer that is cured by active energy ray irradiation to form a transparent resin. The transparent resin can be formed by combining these alone or two or more kinds.

The spectral transmittance characteristics of the compensation filter manufactured in this way are shown in FIG. 29 . That is, the spectral transmittance characteristic of the compensation filter 2Blk of this embodiment is 5% or less for light having a wavelength of 400nm to 550nm, and 70% or more for light having a wavelength of 700nm. In addition, the position of the wavelength at which the transmittance becomes 50% or more is 620 nm to 690 nm.

Therefore, unlike the general absorption type infrared cut filter shown in FIG. 23 , the compensation filter 2Blk according to the present embodiment has a low transmittance in the vicinity of about 600 nm to 650 nm. Therefore, it is possible to further improve the color expression of red after calculation (subtraction).

In addition, the transmittance of the compensation filter 2B1k is preferably equal to that of a red color filter (for example, a red filter having the transmittance characteristics shown in FIG. The transmittance of the optical filter) has a difference within 5%. Specifically, by forming the transmittance characteristic as shown in FIG. 30 , a compensated observed value HDr of red that is not affected by infrared rays and other colors can be obtained, and the color reproducibility of red can be improved.

In addition, the spectral characteristics of the compensating filter 2Blk according to the present embodiment are such that the transmittance is kept low in the wavelength region of 400 to 550 nm, so that visible light is blocked. Therefore, it is possible to suppress the occurrence of color noise with respect to the imaging element to which the compensation filter 2Blk is mounted.

<10th Embodiment>

This embodiment shows another specific example of the compensation filter 2Blk according to the fifth embodiment.

The compensation filter 2Blk according to this embodiment is formed of a pigment paste having the following structure. In addition, the film thickness of the compensation filter is 1.1 μm.

Y139: 11.3 parts,

R254: 4.23 parts,

V23: 19.77 copies.

The spectral characteristics of the compensation filter 2Blk of this embodiment are shown in FIG. 31 . The pigment structure contained in the colored resin composition for compensation filters is that pigment R254 is added to the pigment composition (pigment V23 and pigment Y139) of the ninth embodiment.

In addition, the spectral characteristics of the compensating filter 2B1k according to the present embodiment is a graph of spectral transmittance characteristics with the wavelength (nm) of light as the horizontal axis and the transmittance (%) of light of each wavelength as the vertical axis. On the other hand, the transmittance to light with a wavelength of 400 nm to 550 nm is 5% or less, and the transmittance to light with a wavelength of 700 nm is 70% or more. In addition, the position of the wavelength at which the transmittance becomes 50% is 620 nm to 690 nm.

In addition, the spectral characteristics of the compensation filter 2Blk according to this embodiment are such that visible light is blocked because the transmittance is kept low in the wavelength region of 400 to 550 nm. Therefore, it is possible to suppress the occurrence of color noise with respect to the imaging element to which the compensation filter 2Blk is mounted.

<Eleventh embodiment>

This embodiment relates to an embodiment of an imaging device in which a transparent filter has an ultraviolet absorbing function. The imaging device according to this embodiment includes an imaging unit 110 and a calculation unit 120 .

32 is a schematic diagram showing the configuration of the imaging unit 110 and the computing unit 120 according to the eleventh embodiment of the present invention, and FIG. 33 is a diagram showing the concept of the arrangement state of the color filters in the imaging unit 110 viewed from the incident light side. . 34A and 34B are a V-V' sectional view and a VI-VI' sectional view showing the imaging unit 110 in FIG. 32, respectively.

The imaging unit 110 includes a substrate 111 , a light receiving element 112 , a planarization layer 113 , a color filter 114 , and a microlens 115 .

The substrate 111 is a semiconductor substrate including a wiring layer capable of transmitting and receiving electric signals. The intensity value (electrical signal) of the light received by the light receiving element 112 is sent to the computing unit 120 via the wiring layer.

The light receiving element 112 is formed on the substrate 111 and is a component that receives light and photoelectrically converts it into an electrical signal. As will be described later, in this embodiment, the color filter 114 is formed of three types: a transparent filter 114W, a yellow filter 114Y, and a red filter 114R. Therefore, for convenience, the light-receiving elements that receive the light passing through the transparent filter 114W, the yellow filter 114Y, and the red filter 114R are referred to as the white light-receiving element 112W, the yellow light-receiving element 112Y, and the red light-receiving element 112R, respectively. .

The white light receiving element 112W sends an electric signal obtained from the received light to the blue computing unit 121B.

The yellow light receiving element 112Y sends an electric signal obtained from the received light to the blue computing unit 121B and the green computing unit 121G.

The red light receiving element 112R sends an electrical signal obtained from the received light to the green computing unit 121G and the red computing unit 121R.

The planarization layer 113 is a layer laminated on the light incident side surface of the substrate 111 on which the light receiving element 112 is formed. The surface on which the color filter 114 is installed is flattened by the planarization layer 113 . In addition, the planarization layer 113 is formed of an acrylic resin containing a coumarin-based dye as an ultraviolet absorber at a dye concentration of 5%. Accordingly, the planarizing layer 113 has spectral characteristics such that it exhibits a transmittance of 50% for light having a wavelength of 365 nm to 420 nm, and exhibits a transmittance of 90% or higher for light having a wavelength of 450 nm or greater.

The color filters 114 are members formed adjacent to each other on the respective light receiving elements 112 . In this embodiment, three types of color filters 114 are formed: a transparent filter 114W, a yellow filter 114Y, and a red filter 114R. In addition, one unit of color separation is formed by a total of four pixels including the yellow filter 114Y as two pixels, and each of the transparent filter 114W and the red filter 114R as one pixel. In addition, if the transparent filter 114W, the yellow filter 114Y, and the red filter 114R are expressed as W, Y, and R', respectively, the color filters 114 are formed in an array state as shown in FIG. 33 , for example.

The transparent filter 114W is a colorless and transparent color filter formed of the same material as the planarization layer 113 . That is, the transparent filter 114W is formed of an acrylic resin containing a coumarin-based dye at a dye concentration of 5%. Accordingly, the transparent filter 114W exhibits a transmittance of 50% for light of any wavelength in the light wavelength region of 365 nm to 420 nm, and has a transmittance of 90% or more for light of a wavelength of 450 nm or greater.

The yellow filter 114Y is a filter for extracting yellow light (light composed of a red component and a green component) out of incident light entering the light receiving element. More specifically, it is a filter that transmits wavelengths in the green range or higher including light in the red range and light in the infrared range. As the color material of the yellow filter 114Y, C.I. Pigment Yellow 139 can be used.

The red filter 114R is a filter for extracting red light out of incident light entering the light receiving element. Specifically, it is a filter that transmits wavelengths in the red range or higher including light in the red range. As the color material of the red filter 114R, C.I.Pigment Red 117, C.I.Pigment Red 48:1, and C.I.Pigment Yellow 139 can be used.

The microlens 115 is a member for condensing light onto the light receiving element 112 and is formed on each color filter 114 . In addition, the microlens 115 is formed of the same material as the planarization layer 113 and the transparent filter 114W.

The computing unit 120 includes a blue computing unit 121B, a green computing unit 121G, and a red computing unit 121R. The computing unit 120 obtains the observed values of the three primary colors of light based on the intensity value of the light acquired from the imaging unit 110 . Thereby, data of a color image can be reproduced.

The blue calculation unit 121B is a means for obtaining the observed value of blue light. Specifically, the blue calculation unit 121B acquires electrical signals from the white light receiving element 112W and the yellow light receiving element 112Y. The observed value of the blue light is obtained by subtracting the intensity value of the light obtained from the yellow light receiving element 112Y from the intensity value of the light obtained by the white light receiving element 112W.

The green computing unit 121G is a means for obtaining the observed value of green light. Specifically, the green computing unit 121G acquires electrical signals from the yellow light receiving element 112Y and the red light receiving element 112R. The value of the intensity of light captured by the red light receiving element 112R is subtracted from the value of the intensity of light captured by the yellow light receiving element 112Y to obtain an observed value of green light.

The red computing unit 121R is a means for obtaining the observed value of red light. Here, the red calculation unit 121R uses the intensity value of the light acquired from the red light receiving element 112R as the observed value of red light.

Next, the operation of the imaging element according to this embodiment will be described using the flowchart of FIG. 35 .

First, when light is irradiated from the observation object, a part of the light enters the imaging unit 110 as incident light (step S1 ).

The incident light is collected by the microlens 115 , passes through the color filter 114 and reaches the light receiving element 112 . Here, since the transparent filter 114W, the yellow filter 114Y, and the red filter 114R are formed as the color filter 114, the white light-receiving element 112W, the yellow light-receiving element 112Y, and the red light-receiving element 112R are respectively extracted and removed. Incident light of purple light, yellow light, red light (step S2).

The light that reaches each light receiving element 112 is converted into an electrical signal, and sent to the calculation unit 120 (step S3). Here, the light transmitted through the white light receiving element 112W, the yellow light receiving element 112Y, and the red light receiving element 112R is sent to the computing unit 120 .

Then, the observation values of red light, green light, and blue light are respectively obtained by the computing unit 121 of the computing unit 120 (step S4). Here, if the intensity values of the incident light, yellow light, and red light obtained by each light receiving element are respectively set as Dw, Dy, Dr, and the observed values of the three primary colors of red light, green light, and blue light are respectively set as Db, Dg, Dr, the following formulas (3) and (4) are established.

Db=Dw—Dy ... (3),

Dg=Dy-Dr ... (4).

The data of the three primary colors in each pixel obtained in this way are synthesized to create data of a color image of the observation object (step S5).

As described above, in the imaging unit 110 according to this embodiment, since the planarizing layer 113 and the transparent filter 114W have a transmittance value of 50% for light having a wavelength of 365 nm to 420 nm, and have a transmittance value of 50% for light having a wavelength of 450 nm or more, The light exhibits a spectral characteristic with a transmittance of 90% or more, and therefore an observed value of light in which the influence of ultraviolet rays is removed in the imaging element 20 can be obtained. As a result, it is possible to obtain an observed value of blue light close to human visual sensitivity, and therefore it is possible to provide the imaging unit 110 with good color balance and color reproducibility.

In addition, the imaging unit 110 can realize miniaturization of pixels by forming a microlens 115 for condensing light onto each light receiving element 112 on the color filter 114 . Thereby, a compact imaging element can be provided.

Moreover, since the color filter 114 of the imaging unit 110 includes a yellow filter 114Y and a red filter 114R, it can value to reproduce the color image of the observed object. As a result, noise can be reduced and vivid colors close to primary colors can be reproduced, compared with conventional imaging devices using complementary color filters.

If supplemented, the data of the blue light is obtained from the intensity value of the incident light passing through the transparent filter 114W as shown in the above formula (3). Here, the sensitivity of the light receiving element 112 in the ultraviolet region varies depending on the type of the imaging element. Therefore, when the light receiving element 112 receives incident light containing ultraviolet rays, depending on the type of imaging element, it may be difficult to reproduce the observed data value of blue light in a fixed manner, or insufficient matching with human visual sensitivity may occur. With regard to this problem, if the transparent filter 114W according to this embodiment is used, it is possible to obtain an observed value of light from which the influence of ultraviolet rays has been removed. Therefore, depending on the type of imaging element, the reproducibility and color representation of observed values of blue light can be improved.

In addition, since the flattening layer 113 absorbs the influence of halation from the substrate during pattern exposure when the color filter is formed by photolithography, it is possible to suppress the pixel size of the color filter. That is, by adding an ultraviolet absorber to the planarization layer 113, halation of the exposure light from the substrate 111 can be prevented, and a filter with a good shape can be formed.

In addition, in the imaging device according to the present embodiment, the observed value of blue light is obtained by calculation based on the electric signal obtained through the transparent filter 114W and the electric signal obtained through the yellow filter 114Y. The transparent filter 114W has low transmittance in the short wavelength region and has a rise in transmittance. In addition, the transparent filter 114W is high transmittance in the long wavelength region. Therefore, the transparent filter 114W has a substantially S-shaped spectral transmittance curve. Here, by making the transparent filter 114W have a spectral characteristic curve having a light transmittance of 50% in the light wavelength region of 365 to 420 nm (more preferably having a light transmittance of 50 in the light wavelength region of 390 to 420 nm), % value) has the advantage of being able to make the observed value of blue light obtained by calculation into a blue color with good color balance and reproducibility, which is vivid to the human eye.

To complement this. Fig. 36 is a graph showing stimulation values to human eyes corresponding to changes in light wavelength (nm) in the R (red), G (green), and B (blue) colorimetric systems. As shown in FIG. 36 , the B (blue) vector stimulus value of the human eye has a peak (maximum value) around the light wavelength of 445 nm to 450 nm. Also, on the shorter wavelength side than the wavelength of light that becomes the maximum stimulation value, the wavelength of light that becomes half of the maximum stimulation value (stimulation value of 50% of the maximum stimulation value) is around 420 nm to 425 nm. Therefore, if the transparent filter according to this embodiment is used, it is possible to reproduce vivid blue to human eyes. In addition, as shown in FIG. 1 , the peak of the light transmittance of the conventional blue filter is in the light wavelength region of about 450 nm. In addition, the light transmittance in the light wavelength region of about 450 nm is about 80% (the transmittance is measured based on a glass substrate).

In addition, by setting the light transmittance at 450 nm of the transparent filter 114W to 90% or more, the imaging element according to the present embodiment can enhance blue sensitivity.

In addition, in the present embodiment, the transparent filter 114W is formed of an acrylic resin containing a coumarin-based dye as an ultraviolet absorber at a dye concentration of 5%, but materials other than acrylic resin may be used. Specifically, resins containing one or more of epoxies, polyamides, phenol novolacs, and the like can also be used.

In addition, in the present embodiment, the transparent filter 114W is formed of an acrylic resin containing a coumarin-based dye at a dye concentration of 5%, but as an ultraviolet absorber, a benzotriazole-based compound, diphenylmethane, etc. may also be used. Ketone compounds, salicylic acid compounds, hindered amine compounds, etc. Furthermore, azo dyes, azo metal complex salt dyes, anthraquinone dyes, indigo dyes, thioindigo dyes, phthalocyanine dyes, diphenylmethane dyes, triphenylmethane dyes, xanthene dyes, Oxazine dyes, cation dyes, cyanine dyes, nitro dyes, quinoline dyes, naphthoquinone dyes, oxazine dyes, etc. In addition, difunctional monomers such as 1,6-hexanediol diacrylate or hexanediol diacrylate, neopentyl glycol diacrylate, triethylene glycol diacrylate, or trimethylol trifunctional monomers such as propane triacrylate (trimethirol-ruprohasntriacrylet), pentaerythritol triacrylate, tris(2-hydroxyethyl)isocyanate, or ditrimethylolpropane tetramethacrylate, Photopolymerizable monomer of polyfunctional monomers such as pentaerythritol penta/hexaacrylate. In addition, halomethylated triazine derivatives, halogenated oxadiazole derivatives, imidazole derivatives, benzoethanol ketone alkyl ethers, anthraquinone derivatives, benzoanthrone derivatives, di Photopolymerization initiators of benzophenone derivatives, acetophenone derivatives, thioxanthone derivatives, benzoate derivatives, acridine derivatives, phenazine derivatives, titanium derivatives, and the like. Alternatively, it is also possible to suspend a functional group having ultraviolet absorptivity to the polymer or monomer of the resin, or to the curing agent, or to allow the polymer to have a group that can be taken in and polymerized. For example, quinones or anthracene may be introduced into the polymer, or a monomer having an ultraviolet absorbing group may be added.

In addition, if the above-mentioned ultraviolet absorber is used appropriately, the spectral characteristics of the transparent filter 114W can be changed, and can be set to a half value on the short wavelength side (in the spectral characteristic curve, the light transmittance becomes 50%). wavelength of light). This enables selection of color characteristics (a color close to the actual visual acuity, a color similar to an organic pigment, etc.).

(falling out of pixels)

Here, "drop-out of pixels" will be described.

In recent years, a high-definition CMOS or CCD with more than 6 million pixels has been demanded. In these high-definition CMOS or CCD, etc., it is often necessary to use a color filter with a pixel size of less than 2 μm×2 μm.

However, along with miniaturization of the pixel size, there has been a problem that color filters (pixels) tend to come off. In particular, this problem remarkably occurs in a color filter using a blue organic pigment. This is because the blue color resist has a low transmittance (less than 1%) at 365 nm, which is the wavelength of pattern exposure light, so the exposure light does not reach the lower portion of the blue color resist. That is, when a blue color filter is formed by pattern exposure by photolithography, the part that should be cured is insufficiently cured. On the other hand, pattern exposure light with a light wavelength of 365nm in the red and green material photoresist is sufficiently transmitted through the photoresist (transmittance is about 5 to 10%), and is sufficiently cured to the lower part of the color filter. Therefore, the red and green color filters are more difficult to fall off.

Conversely, in order to completely cure the color photoresist and prevent the color filter from falling off, it is sufficient to increase the transmittance of the blue color photoresist to the pattern exposure light with a wavelength of 365nm. However, when the transmittance in the wavelength region of the pattern exposure light of the blue color resist is increased, the transmittance in the red and green light wavelength regions that should lower the transmittance as the blue color resist increases. , the color separation performance of the blue color filter decreases. Therefore, in conventional image pickup devices using blue, green, and red filters, light corresponding to a plurality of colors is transmitted and color separation deteriorates.

With regard to this problem, since the imaging element according to this embodiment includes a white filter and a yellow filter that are cured by pattern exposure light at a wavelength of 365 nm, it is possible to avoid the phenomenon of pixel dropout. That is, since the observed value of blue can be obtained while avoiding the phenomenon of pixel dropout, it is possible to provide an imaging device capable of improving color separation.

In addition, the micronized color filter has a problem of being easily affected by vignetting from the substrate during pattern exposure in the photolithography process, resulting in coarse pixels. Therefore, there is a problem that color unevenness and color mixing occur.

Regarding this problem, in the imaging element according to this embodiment, since an absorber is added to the planarization layer 113 , the planarization layer 113 absorbs halation of exposure light from the substrate during pattern exposure. As a result, the coarseness of the pixels of the material filter can be suppressed, and a good-shaped filter can be formed. As a result, an imaging device capable of improving color separation can be provided.

<12th Embodiment>

In a twelfth embodiment of the present invention, a method of manufacturing the imaging unit 110 according to the eleventh embodiment will be described.

Hereinafter, a method of manufacturing the imaging unit 110 according to this embodiment will be described with reference to FIGS. 37A to 37D and FIGS. 38A to 38E.

First, the planarization layer 113 is formed on the substrate 111 on which the light receiving elements 112 ( 112W, 112Y in FIG. 37A ) are formed ( FIG. 37A ). Specifically, the planarization layer 113 was formed using an acrylic resin containing a coumarin-based dye at a dye concentration of 5%.

Next, a yellow resin layer YL is formed over the planarization layer 113 . The yellow resin layer YL is a photosensitive resin layer in which organic solvents such as C.I. Pigment Yellow 139, cyclohexanone, and PGMEA, or polymer paints, monomers, and initiators are added to the photosensitive resin.

Next, pattern exposure is performed by using the rubbing M (FIG. 37B). Here, the exposed part undergoes a photochemical reaction and becomes alkaline insoluble.

Then, the portion not irradiated with light is removed with a developer such as an alkaline solution. Thus, the yellow filter 114Y is formed (FIG. 37C). That is, here, the yellow filter 114Y is formed by photolithography.

In addition, although not shown, a red filter 114R is also formed.

Next, after forming the yellow filter 114Y and the red filter 114R, the transparent filter 114W is formed (FIG. 37D).

Next, the lens layer LL made of transparent resin is formed. Specifically, the lens layer LL is formed of the same material as the planarization layer 113 ( FIG. 38A ).

A phenol resin layer 116 is formed on the lens layer LL (FIG. 38B). The phenolic resin layer 116 is formed in order to control the etching rate during dry etching described later and to obtain microlenses of a desired shape. Therefore, the etching rate of the phenolic resin layer 116 is preferably slower than the etching rate of the lens master mold 117M. In addition, the phenolic resin layer 116 plays a role of controlling thermal reflow when a lens master mold 117M described later is formed by thermal reflow.

Furthermore, a photosensitive resin layer 117 is formed on the phenolic resin layer 116 (FIG. 38C). The photosensitive resin layer 117 can be formed of, for example, an acrylic resin having alkali solubility, photosensitivity, and heat reflowability.

Next, the photosensitive resin layer 117 is formed into a rectangular pattern through a photolithography process. Next, it is reflowed and rounded by heat treatment. Thus, a lens master mold 117M is formed (FIG. 38D).

Next, dry etching is performed using the lens master 117M as a mask. As a result, the shape of the lens master mold 117M is transferred to the lens layer LL via the phenolic resin layer 116 to form the microlens 115 ( FIG. 38E ).

The imaging unit 110 can be manufactured by the method described above.

In addition, in the imaging unit 110 , the manufacturing process can be simplified by making the transparent filter 114W and the microlens 115 the same material and having a structure in which the transparent filter 114W and the microlens 115 are integrated.

Specifically, in the present embodiment, the transparent filter 114W and the lens layer LL for forming the microlens 115 are formed separately, but if the transparent filter 114W and the microlens 115 are made of the same material, then it is possible to simultaneously carry out image processing. 37D and the process of FIG. 38A. That is, after the process of FIG. 37C , the portion where the transparent filter 114W is to be formed is filled, and the lens layer LL containing an ultraviolet absorber is formed by one coating to cover the red filter 114R and the yellow filter 114Y. Then, the formation process of the microlens 115 is performed. Accordingly, it is possible to manufacture the imaging unit 110A in which the transparent filter 114W and the microlens 115 are integrally structured as shown in FIG. 39 , and the manufacturing process can be simplified.

In addition, as shown in FIG. 40 , if it is the imaging unit 110B in which the planarization layer 113 is not formed, the manufacturing process can be further omitted.

<13th embodiment>

41 is a schematic diagram showing the configuration of an imaging element according to a thirteenth embodiment of the present invention, and FIG. 42 is a conceptual view of an arrangement state of color filters 114 in an imaging unit 110T according to this embodiment when viewed from the incident light side. . 43A and 43B are a VII-VII' sectional view and a VIII-VIII' sectional view of the imaging unit 110T in FIG. 41 , respectively.

The imaging unit 110T is configured to further include a compensation filter 114Blk in the imaging unit 110 according to the eleventh embodiment. In addition, the compensation filter 114Blk is a member that does not transmit visible light but transmits light in an infrared region to extract infrared rays. For convenience, the light receiving element that receives the light passing through the compensation filter 114Blk is referred to as a black light receiving element 112Blk.

The black light receiving element 112Blk sends an electric signal obtained from the received light to the red computing unit 121R.

In addition, as the color material of the compensation filter 114Blk, a material mixed with C.I.Pigment Red 255, C.I.Pigment Yellow 139, and C.I.Pigment Violet 23 may also be used.

In addition, one set of the transparent filter 114W, the yellow filter 114Y, the red filter 114R, and the compensation filter 114Blk corresponds to one pixel. In addition, if the transparent filter 114W, the yellow filter 114Y, the red filter 114R, and the compensation filter 114Blk are represented as W, Y, R', and Blk, respectively, an arrangement state such as that shown in FIG. 42 is formed. The color filter 114.

The red computing unit 121R acquires electrical signals from the red light receiving element 112R and the black light receiving element 112Blk. Thus, the observed value of the compensated red light is obtained from the intensity value of the light received through the red filter 114R and the intensity value of the light received through the compensation filter 114Blk.

According to the above structure, if the intensity values of the light obtained by the incident light receiving element 112W, the yellow light receiving element 112Y, and the red light receiving element 112R are respectively Dw, Dy, Dr, Dblk, and the blue light, green light, and compensated red light The observed values of Db, Dg, and HDr are respectively, and the calculation expressions shown in the following expressions (5) to (7) are established.

Db＝Dw—Dy……(5)

Dg＝Dy—Dr...(6)

HDr＝Dr—Dblk...(7)

That is, since the imaging unit 110T according to the present embodiment has the compensation filter 114Blk, it is possible to obtain a red observation value with the influence of infrared rays removed. As a result, data of red light close to human visual sensitivity can be obtained, so an imaging device with good color balance and color reproducibility can be provided.

In addition, the imaging element of the present invention in which the compensating filter 114Blk is formed can provide an imaging element with higher sensitivity and better color reproducibility than an imaging element equipped with an infrared cut filter, in addition to the effect of canceling the influence of ultraviolet rays described above. Small camera element.

In addition, in the present embodiment, as shown in FIG. 44 , the compensation filter 114Blk may be configured by optically overlapping a purple filter 114V and a red filter 114R, for example. The violet filter 114V can be formed using C.I. Pigment Violet 23, for example.

(compensation filter)

Here, the compensation filter 114Blk is supplemented.

Solid-state imaging devices such as CCDs and CMOSs have high sensitivity even in regions other than human visible light (for example, 400 nm to 700 nm). In particular, it has high sensitivity to a wavelength region on the long-wavelength side (hereinafter referred to as "infrared region", such as a wavelength region of 700 nm to 1100 nm) longer than the wavelength region of visible light. Here, ordinary organic color filters do not have a light (infrared) cutoff function in the infrared region. Therefore, light outside the range of human visual sensitivity (for example, on the long wavelength side longer than 700 nm) also enters the light receiving element, and the color of the observation object obtained by the imaging element may differ from the color of the observation object observed by humans visually.

Here, the relationship between human visual sensitivity, sensitivity of a light receiving element (SPD sensitivity), and wavelength and transmittance in an ideal infrared cut filter is shown in FIG. 45, for example. If the incident light in the wavelength range corresponding to the hatched portion shown in FIG. 45 is cut off by an infrared cut filter, it is possible to reproduce a color close to human visual sensitivity. In addition, there are two types of infrared cut filters: reflective and absorbing. The relationship between the wavelength of light and the transmittance in the reflective infrared cut filter and the absorbing infrared cut filter is shown, for example, in FIG. 46 .

However, when infrared rays are cut off by an infrared cut filter, the following problems arise.

First, there is a problem that miniaturization of the imaging element is difficult. For example, as a technique of inserting an infrared cut filter into an optical system of an imaging element, techniques proposed in JP-A-2000-19322 and JP-A-63-73204 can be cited. However, in these technologies, an infrared cut filter is inserted so as to cover the entire light-receiving element such as a CMOS or a CCD. Therefore, due to the thickness of the infrared cut filter, it is difficult to miniaturize the imaging element including the optical system. For example, an absorption type infrared cut filter has a thickness of about 1 to 3 mm.

In addition, there is a problem that it is difficult to reduce the manufacturing cost. That is, when a color filter is used as a camera component, a process of assembling the infrared cut filter into the lens system is required, so it is difficult to reduce the manufacturing cost.

Such a problem can be solved by using a compensation filter and eliminating the influence of infrared rays by calculation.

In addition, in an imaging element equipped with color filters of the three primary colors of light (R, G, B) or complementary color filters (C, M, Y), there is a problem that the sensitivity of the imaging element will decrease if an infrared cut filter is used. drop problem. This is because, in an imaging element using an infrared cut filter, infrared rays are cut off for all light receiving elements. Therefore, the infrared cut filter may absorb light in the visible light wavelength region of 550 nm to 700 nm, and there is a problem that the sensitivity of an imaging element including green and red color filters or the like is lowered.

This problem can be solved by using the transparent filter 114W, the yellow filter 114Y, the red filter 114R, and further the compensation filter 114Blk. That is, it is realized by calculating the observed values of blue, green, and red light according to the intensity values of light obtained through the transparent filter 114W, yellow filter 114Y, red filter 114R, and compensation filter 114Blk. The three primary colors of light can be reproduced without causing a decrease in sensitivity. Furthermore, since the compensation filter 114Blk is used, it is possible to remove the influence of infrared rays only from the observed value of red light.

(first embodiment)

Hereinafter, a method of manufacturing a solid-state imaging device according to an example of the present embodiment will be described.

First, on the semiconductor substrate 111 on which the light-receiving element 112, the light-shielding film, and the passivation film are formed, a thermosetting acrylic resin coating solution containing a coumarin dye at a dye concentration of 5% is spin-coated, and then heat-treated to realize dura mater. Thus, the planarization layer 113 made of transparent resin is formed. The spectral characteristics after hard coating of this planarization layer 113 are as shown in a1 of FIG. 47 . In addition, for comparison, the spectral characteristics when the dye concentration of the coumarin-based dye is 1% and 10% are shown in a2 and a3, respectively.

Next, the color filters of the yellow filter 114Y, the red filter 114R, and the compensation filter 114Blk are respectively formed by three photolithography processes. The pixel pitch is 2.5 μm. In addition, the arrangement of each filter is the same as the example shown in FIG. 42 .

The color photoresist (yellow resin layer YL) used to form the yellow filter 114Y uses C.I.Pigment Yellow 139 as the color material, and also uses organic solvents such as cyclohexanone and PGMEA, polymer paint, monomers, and initiators A structure added to photosensitive acrylic resin.

The color photoresist used to form the red filter 114R uses C.I.Pigment Red177, C.I.Pigment Red 48:1, and C.I.Pigment Yellow 139 as color materials. Other structures are the same as the case of the yellow filter 114Y.

The color photoresist used to form the compensation filter 114Blk uses C.I.Pigment Red254, C.I.Pigment Yellow 139, and C.I.Pigment Violet 23 as color materials. Other structures are the same as the case of the yellow filter 114Y.

Next, the same acrylic resin coating solution as that used for the planarization layer 113 was coated on the color filter 114 so as to have a film thickness of 0.8 μm. Then, a hard coating treatment was performed by heating at 200° C. for 6 minutes to form a lens layer LL. Next, a phenolic resin was applied to a film thickness of 1.0 μm to form the phenolic resin layer 116 . The phenolic resin layer 116 has an etching control function and a thermal reflow control function. Furthermore, an acrylic resin (lens master material) having alkali solubility, photosensitivity, and thermal fluidity is applied to form the photosensitive resin layer 117 .

Next, the photosensitive resin layer 117 (lens master material) is formed into a rectangular pattern by a photolithography process using a developer. Then, it was made to flow by heat treatment at 200°C. Thus, a hemispherical lens master mold 117M is formed. In addition, a smooth hemispherical lens master mold 117M with a gap between lens master molds of 0.35 μm can be formed at a substantially appropriate flow rate of 0.45 μm in height and 0.15 μm in one side.

Finally, an etching process is performed using a dry etching device using a mixed gas of fluorine-based gases C3F8 and C4F8, using the lens master mold 117M as a mask. As a result, microlenses 115 with narrow inter-lens gaps substantially eliminating inter-lens gaps are formed.

In addition, the etching rate of the acrylic resin used in this embodiment is 1.2 times faster than that of the resin constituting the lens master mold 117M. The photosensitive resin layer 117 serving as the base resin of the lens master mold 117M can increase the aperture ratio of the microlens 115 by processing the microlenses with relatively small surface roughness into narrow gaps. If the etching rate of the resin constituting the lens master 117M is the same as that of the photosensitive resin layer 117 and the lens layer LL, the shape of the microlens 115 can be processed into substantially the same size and shape as the lens master 117M.

In the imaging device manufactured in this way, the transparent filter 114W, the yellow filter 114Y, the red filter 114R, and the compensation filter 114Blk have the spectral characteristics shown in FIG. 48 . In FIG. 48, b1, b2, b3, and b4 represent the spectral characteristics of the transparent filter 114W, the yellow filter 114Y, the red filter 114R, and the compensation filter 114Blk, respectively. As shown in FIG. 48 , the spectral characteristic curve of each filter has a low transmittance in the short wavelength region and has a rise in transmittance. In addition, the transmittance becomes high in the long wavelength region. Therefore, it becomes substantially S shape.

In addition, by performing color calculations in the above-mentioned expressions (5) to (7), it is possible to obtain an imaging element having blue, green, and red filters externally having spectral characteristics as shown in FIG. 49 . In FIG. 49, c1, c2, and c3 represent the spectral characteristics of the blue, green, and red color filters on the outside, respectively.

In addition, spectroscopic measurement was performed as follows.

First, the film thickness of each color filter 114 on the light receiving element 112 and the film thickness of the transparent resin (planarization layer 113 and lens layer LL) are measured. Regarding the transparent resin, a film was formed on a Si substrate, and the film thickness thereof was measured with a contact-type film thickness meter (Dektak IIA manufactured by Sloan Corporation).

Next, a transparent resin having the same film thickness as the measured film thickness and a color filter 114 were formed on the glass substrate 111, and the spectrum was measured with a spectrophotometer (U-3400spectrophotometer manufactured by Hitachi, Ltd.). At this time, only the spectral characteristics of the color filter and the transparent resin were measured based on the glass substrate (a glass substrate without the color filter and the transparent resin). In addition, the value of the transmittance is 100% with transparent glass having a refractive index of 1.5.

(second embodiment)

In this example, a thermosetting acrylic resin coating solution containing a benzotriazole dye at a dye concentration of 5% was used, and the coating solution was spin-coated to form the planarizing layer 113, the transparent filter 114W, Lens layer LL. Other than that, the imaging element was produced in the same manner as in the first example.

Here, the spectral characteristics of a transparent resin containing a benzotriazole-based dye at a dye concentration of 5% are shown in d1 of FIG. 50 . In addition, for comparison, the spectral characteristics when the dye concentration of the benzotriazole dye is 1% and 10% are shown in d2 and d3, respectively.

In the imaging device thus produced, the spectral characteristics of the transparent filter 114W, the yellow filter 114Y, the red filter 114R, and the compensation filter 114Blk are as shown in e1, e2, e3, and e4 of FIG. 51, respectively.

In addition, by performing the color calculations in the above-mentioned expressions (5) to (7), it is possible to obtain an imaging element having blue, green, and red filters externally having the spectral characteristics shown in FIG. 52 . In FIG. 52, f1, f2, and f3 represent the spectral characteristics of the blue filter, green filter, and red filter on the outside, respectively.

In this way, by changing the spectral characteristics of the transparent resin layer (the planarizing layer 113 , the transparent filter 114W, and the lens layer LL), it is possible to set a half value on the short wavelength side. Therefore, it is possible to select color characteristics (a color actually close to visual sensitivity, or a color similar to an organic pigment, etc.).

In addition, as a side effect, it is possible to prevent halation caused by reflection of pattern exposure light on the substrate when forming the color filter by photolithography. Therefore, a color filter with high resolution can be formed.

In addition, in this embodiment, since the influence of infrared rays can be removed by arithmetic processing using the compensation filter 114Blk, the infrared cut filter can be omitted.

In addition, from the viewpoint of simplifying the manufacture of the imaging element, it is also possible to manufacture an imaging element having a structure that does not use the compensation filter 114Blk by the same method without considering the influence of infrared rays. In this case, an infrared cut filter is used, but in photolithography including pattern exposure and development, the color filter for forming the yellow filter 114Y and the color filter for forming the red filter 114R may pass through. The advantage of processing the color filter twice into the color omits the process. Furthermore, if the transparent color filter and the microlens are integrated, the process can be further omitted. On the other hand, in order to form the blue, green, and red color filters used in a normal imaging device, three times of coloring are required.

<14th embodiment>

The imaging element 201 of the present embodiment includes at least two or more filters, and includes: a first filter that has suppressed transmission characteristics for light on the short-wavelength side shorter than the first wavelength; The light on the long-wavelength side has a transmission characteristic; and the second filter has a transmission characteristic on the light on the long-wavelength side longer than the second wavelength. In addition, each filter according to the present embodiment has transmission suppression characteristics in the short wavelength region and has transmission characteristics in the long wavelength region. In addition, in terms of spectral characteristics, it is preferable to have a substantially S-shaped transmittance curve.

Light incident through the first filter and the second filter is received by the first light receiving element and the second light receiving element, respectively, and converted into an electrical signal.

Specifically, the imaging element 201 has a first wavelength region that exhibits a transmittance of 10% or less in the wavelength region of 350nm to 750nm, and has a transmittance in the wavelength region of 450nm to 1100nm that is longer than the first wavelength region. Filters F1 to F7 with a transmittance of 90% or more. In addition, the 1st optical filter and the 2nd optical filter are the names which show a relative relationship, and the optical filter F1 - the optical filter F7 can respectively become a 1st optical filter and a 2nd optical filter.

Filters F1 to F7 are respectively used to capture white light (transparent), greenish blue light, yellow-green light, yellow light, orange light, red light, and infrared light (shown as black for convenience). Specifically, the spectral characteristics of the filters F1 to F7 are as shown in L1 to L7 of FIG. 53 , respectively.

In addition, in this embodiment, the color filters F1 , F4 , and F6 correspond to the clear filter 2W, the yellow filter 2Y, and the red filter 2R, respectively.

Next, a method for obtaining observed values for reproducing incident light received by each of the filters F1 to F7 will be described.

First, when light is incident on the imaging element 201, the corresponding first light-receiving element and second light-receiving element pass through the first filter and the second filter as any one of the filters F1 to F7. The element receives incident light. Convert the received light into an electrical signal.

Next, as conceptually shown in FIG. 54 , based on the data value D1 of light received by the first filter and the data value D2 of light received by the second filter, the relationship between the first filter and the first filter is obtained. 2 The data value DC of the wavelength corresponding to the difference between the wavelength regions of the light received by the filter.

In other words, the first filter and the second filter constitute an apparent color filter of a color corresponding to the difference in the respective wavelength regions.

For example, the observed value Db of blue can be obtained from the filter F1 (white) and the filter F4 (yellow). The observed value Dg of green can be obtained by the filter F4 (yellow) and the filter F6 (red). According to the filter F6 (red) and the filter F7 (black), the data value HDr of red which is not affected by infrared rays can be obtained.

In this way, the data values of the three primary colors of light can be obtained, and the received incident light can be reproduced.

Furthermore, for example, by subtracting the filter F2 (greenish blue) and the filter F3 (yellow-green), the numerical value of the greenish blue (blue interlaced with green) can be obtained. Through the subtraction of filter F3 (yellow-green) and filter F4 (yellow), the value of yellow-green can be obtained. The value of yellow can be obtained by subtracting the filter F4 (yellow) and the filter F5 (orange). The orange value can be obtained by subtracting the filter F5 (orange) and the filter F6 (red).

That is, according to the method described above, by using two filters composed of the first filter and the second filter among the filters F1 to F7, not only the received incident light is reproduced, but also More detailed color extraction is possible.

In addition, although seven kinds of filters F1 to F7 were exemplified in this embodiment, the present invention is not limited thereto. That is, as long as it has a first wavelength region showing a transmittance of 10% or less in the wavelength region of 350nm to 750nm, and has a transmittance in the wavelength region of 450nm to 1100nm, which is a long wavelength region longer than the first wavelength region The present embodiment does not exclude color filters in the wavelength range of 90% or more.

In addition, in the imaging element 201 according to this embodiment, a high-ratio color filter with the highest color material content ratio in the color filter can be formed by dry etching, and a low-ratio color filter other than the high-ratio color filter can be formed by photolithography. of color filters.

<Fifteenth embodiment>

In this embodiment, the transmittances of the plurality of filters including the color filter, the compensation filter, and the transparent filter increase (increase) in different wavelength regions, respectively.

FIG. 55 is a front view showing an example of an imaging element according to this embodiment. In this FIG. 55 , an example of the state of the filters F1 to F7 of the imaging device 210 viewed from the light incident side is shown. Filters F1-F7 include color filters, compensation filters, and transparent filters.

The light receiving elements (photoelectric conversion elements) H1 to H7 receive incident light through the filters F1 to F7 respectively, and output the observed values E1 to E7 to the computing unit 62 .

The calculation unit 220 performs subtraction processing on the observed values observed through any two filters among the observed values E1-E7 of the plurality of light-receiving elements H1-H7 observed through the filters F1-F7, and obtains the The observed value of the light in the wavelength region corresponding to any two sets of filters is output as the calculated observed value.

FIG. 56 is a graph showing an example of the relationship between light wavelengths and transmittances of the filters F1 to F7 included in the imaging device 210 .

The plurality of filters F1 to F7 included in the imaging element 210 according to this embodiment each have a characteristic of suppressing the transmission of light on the short-wavelength side shorter than the wavelengths WL1 to WL7 of the part where the transmittance increases, and has the characteristic of suppressing transmission of light on the short-wavelength side compared with the wavelengths WL1 to WL7 of the portion where the transmittance increases. The light transmission characteristics on the long-wavelength side where the wavelengths WL1 to WL7 of the transmittance increase portion are long.

In the imaging element 210, light incident through the filters F1 to F7 is observed by the light receiving elements (photoelectric conversion elements) H1 to H7. The calculation unit 220 inputs the respective observed values E1 to E7 of the light receiving elements H1 to H7 .

The filters F1 to F7 have spectral curves in which the transmittance is low in the short wavelength region shorter than the portion where the transmittance rises, and the transmittance is high in the long wavelength region, and the transmittance increases in a substantially S-shape. The filters F1 to F7 have increased transmittances in different wavelength regions, respectively.

In this embodiment, the filter F1 is a transparent filter (for example, a colorless and transparent filter).

The filter F4 is a yellow color filter used to extract the yellow component of light.

The filter F6 is a red color filter used to extract the red component of light.

The filter F7 is a compensation filter having a property of suppressing transmission of light in the visible light wavelength range and a property of transmitting light on the longer wavelength side than the visible light wavelength range.

In the characteristics of light transmittance and wavelength, the wavelength WL2 of the part where the transmittance of the filter F2 increases is between the wavelength WL1 of the part where the transmittance of the filter (transparent filter) F1 increases and the transmittance of the filter F3 The wavelength of the rising part is between WL3. For example, the wavelength WL2 of the part where the transmittance of the filter F2 is increased is the wavelength between the wavelength WL1 of the part where the transmittance of the filter (transparent filter) F1 is increased and the wavelength WL3 of the part where the transmittance of the filter F3 is increased. The wavelength division is divided into two regions.

In addition, in the characteristics of light transmittance and wavelength, the wavelength WL4 of the part where the transmittance of the filter (yellow filter) F4 rises, the wavelength WL3 of the part where the transmittance of the filter F3 rises, and the wavelength WL3 of the filter ( The wavelength WL6 of the part where the transmittance of the red filter) F6 rises.

Similarly, the wavelength WL5 of the portion with increased transmittance of the filter F5 is between the wavelength WL4 of the portion with increased transmittance of the filter F4 and the wavelength WL6 of the portion with increased transmittance of the filter (red filter) F6.

In the characteristics of light transmittance and wavelength, the wavelength WL4 of the part where the transmittance of the filter (yellow filter) F4 increases is set on the short wavelength side shorter than the wavelength WL5 of the part where the transmittance of the filter F5 increases , the transmittance increases. For example, the wavelengths WL4 and WL5 of the parts where the transmittance of the filters F4 and F5 increase, the wavelength WL3 of the part where the transmittance of the filter F3 increases and the wavelength of the part where the transmittance of the filter (red filter) F6 increases The wavelength division between WL6 is divided into 3 regions.

As described above, the calculation unit 220 performs subtraction processing on the observed values of the incident light observed through any two filters among the observed values of the incident light observed through the filters F1 to F7, among the observed values E1 to E7 of the incident light observed through the filters F1 to F7. The observed value of the light in the wavelength region corresponding to the set of any two filters.

For example, the calculation unit 220 subtracts the observed value E4 observed through the filter (yellow filter) F4 from the observed value E1 observed through the filter (transparent filter) F1, and outputs the observed value G1 of blue. .

In addition, for example, the calculation unit 220 subtracts the observed value E6 observed through the filter (red filter) F6 from the observed value E4 observed through the filter (yellow filter) F4, and outputs a green observed value. G2.

In addition, for example, the calculation unit 220 subtracts the observed value E7 observed through the compensation filter F7 from the observed value E6 observed through the filter (red filter) F6, and outputs a red color from which the influence (component) of infrared rays has been removed. The observed value of G3.

In addition, the calculating part 220 can obtain the observed numerical value of a more detailed color by using the filters F2, F4-F6.

For example, the computing unit 220 subtracts the observed value E3 observed through the filter F3 from the observed value E2 observed through the filter F2 to output an observed value G4 interlaced with green and blue.

For example, the computing unit 220 subtracts the observed value E4 observed through the filter (yellow filter) F4 from the observed value E3 observed through the filter F3 to output a yellow-green observed value G5.

For example, the calculation unit 220 subtracts the observed value E5 observed through the filter F5 from the observed value E4 observed through the filter (yellow filter) F4, and outputs the observed value G6 of yellow.

For example, the calculation unit 220 subtracts the observed value E6 observed through the filter (red filter) F6 from the observed value E5 observed through the filter F5, and outputs an orange observed value G7.

The transmittance of the filters F1 to F7 is preferably 90% or more when the wavelength of light is on the longer wavelength side than 750 nm. This is to cut off the light components in the infrared region and observe the intensity of the light components in the human visible light wavelength region with high precision.

The sensitivity of the light-receiving elements (photoelectric conversion elements) H1 to H7 in the short-wavelength region may vary depending on the manufacturer.

When an ultraviolet absorber is added to the filter (transparent filter) F1, the wavelength of light having a transmittance of 50% of the filter F1 is preferably between 350nm and 400nm (ultraviolet region). Therefore, the wavelength of light at which the transmittance of the filters F1 to F7 is 50% is preferably 350 nm or more.

On the other hand, when no ultraviolet absorber is added to the filter (transparent filter) F1, it is preferable that the transmittances of the other filters F2 to F7 other than the filter F1 become 50%. The wavelength of light is 400 nm or more, and the transmittance of the filter F1 is 90% or more when the wavelength of light is 400 nm or more.

Thereby, it is possible to reduce the influence of sensitivity difference of each manufacturer of the light receiving elements H1 to H7, and it is possible to obtain blue observed values under certain conditions.

In addition, the visual sensitivity of human beings is about between 400nm and 700nm in wavelength. In order to adjust the sensitivity of the red region and adjust the observed value of red, it is preferable to make the wavelength of the light with a transmittance of 50% of the filters F1-F7 be 750nm the following.

Through the above discussion, in the case where an ultraviolet absorber is added to the filter (transparent filter) F1, it is preferable that the plurality of filters F1 to F7 have a light transmittance of 50 in the region of 350nm to 750nm. % or more, when the wavelength of light is longer than about 750 nm, the light transmittance is 90% or more.

In addition, when no ultraviolet absorber is added to the filter (transparent filter) F1, it is preferable that the plurality of filters F2 to F7 other than the filter F1 have a wavelength of light of 400nm to 750nm The light transmittance has a value of 50% in the region of , and the light transmittance is 90% or more in the case where the wavelength of light is on the long-wavelength side longer than approximately 750nm, and the filter F1 is in the region on the long-wavelength side longer than 400nm Medium light transmittance is above 90%.

In addition, in this embodiment, microlenses may be provided on the light incident sides of the filters F1 to F7, and the filter F1 and the microlenses may be formed of the same transparent resin.

As explained above, by properly selecting filters with different spectral characteristics (such as F1 to F7) whose transmittances increase sharply in different wavelength regions, and disposing the selected filters on the light-receiving element, based on the light-receiving element By calculating the obtained observation data, in addition to red (R), green (G), and blue (B), observation values of other finer color components can be obtained.

In addition, the compensation filter according to each of the above-described embodiments is produced by mixing a red pigment and a violet pigment, and can be formed so that the transmittance becomes 50% at a wavelength of about 660 nm.

In addition, by mixing a red pigment and a cyan pigment to produce a compensation filter, a compensation filter having a transmittance of 50% at a wavelength of about 740 nm can be obtained.

Industrial Applicability

According to the present invention, it is possible to provide an imaging device with good color balance and color reproducibility.

Claims (29)

1. An imaging element, comprising: a filter for extracting a specific color component in incident light; a light receiving element for observing the above-mentioned incident light through the filter, characterized in that, The above filters include: transparent filter; Yellow filter for extraction of yellow components; Red filter for extraction of red components. 2. The imaging element according to claim 1, wherein: The above-mentioned light-receiving element also has: The incident light receiving element observes the above-mentioned incident light through the above-mentioned transparent filter; The yellow light-receiving element observes the above-mentioned incident light through the above-mentioned yellow filter; The red light receiving element observes the above-mentioned incident light through the above-mentioned red filter; A calculation unit for obtaining the observation result of blue by subtracting the observation result observed by the above-mentioned yellow light-receiving element from the observation result observed by the above-mentioned incident light light-receiving element; A computing unit that subtracts the observation result observed by the red light receiving element from the observation result observed by the yellow light receiving element to obtain the green observation result. 3. The imaging element according to claim 1 or 2, wherein A transparent flattening layer covering the yellow filter and the red filter and forming the transparent filter is further provided. 4. The imaging element according to claim 3, wherein: It further includes a microlens formed from the transparent flattening layer to condense light onto the light receiving element. 5. The imaging element according to claim 2, wherein: The above-mentioned transparent filter absorbs ultraviolet rays in a wavelength region shorter than 400nm. 6. The imaging element according to claim 5, wherein The above transparent filter has the following spectroscopic characteristics: The light transmittance exhibits a value of 50% for light having any wavelength in the wavelength region of 365 nm to 420 nm, and becomes 90% or higher for light having a wavelength of 450 nm or more. 7. The imaging element according to claim 6, wherein The above-mentioned transparent filter has the following spectroscopic characteristics: for light having any wavelength in the wavelength region of 390nm to 420nm, the light transmittance shows a value of 50%; light transmittance. 8. The imaging element according to claim 2, wherein: The above-mentioned transparent filter, the above-mentioned yellow filter and the above-mentioned red filter are arranged adjacently in a grid to form a unit of color separation; The number of pixels of the yellow filter is equal to the total number of pixels of the transparent filter and the red filter. 9. The imaging element according to claim 2, wherein The above-mentioned optical filter further includes a compensation filter having a transmission suppression characteristic in the visible light wavelength region and a transmission characteristic on a longer wavelength side than the visible light region. 10. The imaging device according to claim 9, wherein: The light receiving element further includes a compensation light receiving element for observing the incident light through the compensation filter; It further includes an arithmetic unit for subtracting the observation result observed by the compensating light receiving element from the observation result observed by the red light receiving element to obtain a compensated red observation result. 11. The imaging element according to claim 10, wherein: The compensation filter has a transmission characteristic substantially at the same level as that of the red filter on the longer wavelength side than the visible light wavelength region. 12. The imaging element according to claim 11, wherein: The difference between the light transmittance of the above-mentioned compensation filter and the light transmittance of the above-mentioned red filter is in the range of about 5% in the light wavelength region of about 400nm to 550nm and in the wavelength region longer than 750nm; The compensation filter has a light transmittance of 50% in the light wavelength region of about 630 nm to 750 nm. 13. The imaging element according to claim 12, wherein: The compensation filter described above is formed by optical superimposition of multiple colors. 14. The imaging element according to claim 13, wherein: The aforementioned compensation filter is formed by optically superimposing two colors of violet and red. 15. The imaging element according to claim 13, wherein: The aforementioned compensation filter is formed by optically overlapping two colors of cyan and red. 16. The imaging element according to claim 13, wherein: The aforementioned compensation filter is formed by stacking a plurality of filters. 17. The imaging element according to claim 10, wherein: The transparent filter, the yellow filter, the red filter, and the compensation filter are adjacently arranged in a grid to form a unit of color separation. 18. The imaging device according to claim 10, wherein: The compensation filter above shows a transmittance of less than 5% for light in the wavelength range of 400nm to 550nm; Shows a transmittance of 50% for light having any wavelength in the wavelength range of 620nm to 690nm; It exhibits a transmittance of 70% or more for light having a wavelength of 700 nm. 19. The imaging element according to claim 18, wherein: The aforementioned compensation filter is formed of a colored resin composition containing at least C.I. Pigment Violet 23 and C.I. Pigment Yellow 139 pigments. 20. The imaging element according to claim 18, wherein: The aforementioned compensation filter is formed of a colored resin composition containing at least C.I.Pigment Violet 23 and C.I.PigmentYellow 139 and C.I.Pigment Red 254 pigments. 21. The imaging device according to claim 2 or 10, characterized in that, Having a substrate on which the above-mentioned light-receiving element is arranged; A light-shielding film for suppressing reflection and transmission of light other than the incident light incident on the light receiving element is provided on the substrate other than the area where the incident light is incident on the light receiving element. 22. The imaging device according to claim 21, wherein The above-mentioned light-shielding film has an ultraviolet absorbing function. 23. The imaging device according to claim 22, wherein: The light-shielding film has an infrared absorption function. 24. The imaging device according to claim 23, wherein A film having at least one of an ultraviolet absorbing function and a near infrared absorbing function is laminated on the light shielding film. 25. An imaging element, which uses a plurality of photoelectric conversion elements to receive incident light through a plurality of filters, characterized in that it has: The first optical filter is one of the above-mentioned plurality of optical filters, is any filter included in the above-mentioned plurality of optical filters, and has a transmission suppression characteristic for light on a wavelength side shorter than the first wavelength, has a transmission characteristic for light on a wavelength side longer than the first wavelength; The second optical filter is another optical filter different from the above-mentioned first optical filter among the above-mentioned plurality of optical filters, and has a transmission suppression characteristic for light on the wavelength side shorter than the second wavelength. The light on the longer wavelength side has transmission characteristics, wherein the above-mentioned shorter wavelength side than the second wavelength is longer than the above-mentioned first wavelength side; The first photoelectric conversion element is one of the plurality of photoelectric conversion elements, and receives incident light through the first optical filter; The second photoelectric conversion element is another photoelectric conversion element different from the first photoelectric conversion element among the plurality of photoelectric conversion elements, and receives incident light through the second optical filter; and The calculation unit performs subtraction processing on the observed value of light observed by the first photoelectric conversion element and the observed value of light observed by the second photoelectric conversion element, and obtains the difference between the first optical filter and the second photoelectric conversion element. The observed value of the color of light corresponding to the difference in the wavelength region of the filter. 26. The imaging device according to claim 25, wherein The above-mentioned first wavelength is any wavelength in the wavelength region of 350 nm to 750 nm. 27. The imaging element according to claim 25 or 26, wherein The above-mentioned first optical filter is a transparent optical filter having a light transmittance of 90% or more in a wavelength region of light longer than 400 nm; Among the plurality of optical filters described above, the optical filter having the characteristic that the transmittance of light increases on the longest wavelength side has a transmission suppression characteristic in the visible light wavelength region, and has a transmission characteristic on the longer wavelength side than the visible light wavelength region. compensation filter; Filters other than the above-mentioned compensating filter have a light transmittance of 50% in the wavelength range of light from about 350nm to 750nm, and when the wavelength of light is longer than about 750nm , the light transmittance showed a value of 90% or more. 28. An imaging device, comprising: an imaging element that detects the intensity value of light having a specific wavelength region in incident light; and an arithmetic unit that reproduces the incident light based on the intensity value of light detected by the imaging element, characterized in that, The above camera elements have: semiconductor substrate; a photoelectric conversion element formed on the above-mentioned semiconductor substrate for receiving incident light; a transparent filter formed on the above-mentioned photoelectric conversion element to transmit the above-mentioned incident light; A red filter, formed on the above-mentioned photoelectric conversion element, is used to extract the red component in the above-mentioned incident light; a yellow filter, formed on the above-mentioned photoelectric conversion element, for extracting the yellow component in the above-mentioned incident light; a transparent resin layer formed to cover the color filter; and A microlens formed on the above-mentioned color filter; The above arithmetic unit also has: A unit that subtracts the intensity value of the incident light received through the above-mentioned yellow filter from the intensity value of the incident light received through the above-mentioned transparent filter to perform subtraction processing, and calculates the value of the blue component of the incident light; Means for calculating the value of the green component of the incident light by subtracting the intensity value of the incident light received through the red filter from the intensity value of the incident light received through the yellow filter to perform subtraction processing. 29. The imaging device according to claim 28, wherein: The above-mentioned imaging element is further equipped with a compensation filter for extracting infrared components in the above-mentioned incident light; The calculation unit further includes a unit for calculating the value of the red component of the incident light by subtracting the intensity value of the incident light received through the compensation filter from the intensity value of the incident light received through the red filter to perform subtraction processing. .

Images