JP5200319B2 - Image sensor - Google Patents

Description

  The present invention relates to an image pickup device including a light receiving element, and more particularly to an image pickup device in which a color filter is disposed on a light incident side of a light receiving element so that a color component to be observed can be observed.

  Examples of the image sensor (image sensor) include a two-dimensional image sensor used in a digital camera, a video camera, or the like, or a one-dimensional image sensor such as a linear sensor used in a facsimile or a copying machine.

  A light receiving element (photoelectric conversion element) such as a CMOS or a CCD provided in the image pickup element converts light incident on the element into an electrical signal. The light receiving element has high sensitivity even in a region outside the visible light wavelength region (for example, a wavelength region of 400 nm to 700 nm) which is a human visual sensitivity region, and in particular, a wavelength region on the longer wavelength side than the visible light wavelength region (hereinafter referred to as a wavelength region below) , “Infrared region” (for example, a wavelength region of 700 nm to 1100 nm) has high sensitivity.

  On the light incident side of each light receiving element, an organic color filter of three primary colors (or complementary colors) is installed in order to perform color separation for extracting a specific color component from the incident light. The light receiving element receives incident light via the organic color filter. Since the incident light is color-separated by the organic color filter, the color component to be observed is observed by the light receiving element.

  The light receiving element does not determine the color of the incident light, but only converts the incident light into an electrical signal corresponding to the intensity of the light and detects the brightness of the incident light. For this reason, organic light filters of red (R), green (G), and blue (B), which are the three primary colors of light, are provided on the light incident side of the light receiving element. The organic color filter color-separates light from a subject to be taken out and extracts specific light. The light that has passed through the red, green, and blue color filters is incident on a light receiving element that faces each color filter, and is converted into an electrical signal by each of the light receiving elements. By synthesizing output values (usually voltage values) obtained by photoelectric conversion, it is possible to reproduce the photographing object as a color image.

  However, since the organic color filter does not have a function of cutting light in the infrared region (infrared light), light outside the human visual sensitivity region (for example, longer wavelength side than 700 nm) may be incident on the light receiving element. For this reason, there is a problem that the color of the photographing target obtained by the image sensor may be different from the color of the photographing target observed by human eyes.

  In order to avoid such color separation that is affected by light outside the human visual sensitivity range, an infrared cut filter is used. That is, the infrared cut filter cuts light in the infrared region from the incident light. Thereafter, the light whose infrared region is cut is made incident on each color filter to reduce the influence of the infrared region.

  FIG. 21 is a graph illustrating an example of a preferable relationship between the transmittance of the infrared cut filter with respect to human visual sensitivity, sensitivity of the light receiving element (SPD sensitivity), and sensitivity of the light receiving element.

  The sensitivity of the light receiving element extends to the infrared region. For this reason, measurement close to human visual sensitivity is possible by suppressing the observation of the infrared region of the light receiving element by the infrared cut filter. That is, if the light of the hatched portion in FIG. 21 is cut by the infrared cut filter, the light receiving element can measure close to human visual sensitivity.

  There are two types of infrared cut filters, a reflection type and an absorption type.

  FIG. 22 is a graph showing an example of the relationship between the wavelength of light and the transmittance in a reflection-type infrared cut filter and an infrared absorption-type infrared cut filter.

  The reflective infrared cut filter is configured by forming an inorganic multilayer film on a glass plate, for example. Reflective type infrared cut filter with inorganic multilayer film has high infrared cut function for incident light in the direction perpendicular to the filter surface, but sufficient cut function for angled infrared rays such as oblique incident Is difficult to realize.

  The absorption type infrared cut filter absorbs infrared rays by utilizing absorption of light by dyes or copper ions. A general absorption-type infrared cut filter is configured by putting a metal ion such as copper ion or an organic pigment in a base material such as inorganic glass.

  Here, when comparing the reflection type infrared cut filter and the absorption type infrared cut filter, the absorption type infrared cut filter is less expensive than the reflection type infrared cut filter. Further, as described above, the absorption type infrared cut filter has better infrared cut performance of incident light with an angle than the reflection type infrared cut filter.

  Therefore, in general, the absorption type infrared cut filter tends to be used more than the reflection type infrared cut filter.

  In addition, in order to supplement the cut function of the reflective infrared cut filter by the inorganic multilayer film and reduce the influence of oblique incidence or re-incidence of infrared rays, the reflective infrared cut filter by the infrared absorption type infrared cut filter and the inorganic multilayer film is used. A filter may be used in combination.

  However, when an infrared absorption type infrared cut filter and a reflection type infrared cut filter are used in combination, the structure becomes complicated. Therefore, it is common to use only an infrared absorption type infrared cut filter.

  In general image sensors, an optical system including a lens or the like is provided on the light incident side of the light receiving element in order to observe light from a subject to be photographed. In order to prevent the observation result from being affected by the infrared rays described above, a technique of inserting an infrared cut filter into the optical system of the image sensor has been proposed (for example, see Patent Literature 1 and Patent Literature 2).

  Patent Document 1 has a function of correcting color purity by selectively cutting light in a specific wavelength region at a boundary between red light and green light and / or a boundary between green light and blue light, and A solid-state imaging device including a color purity correction filter having a function of cutting infrared rays is described.

  Further, in Patent Document 2, an infrared absorber capable of significantly reducing the transmittance in the infrared light region and transmitting the light in the visible light wavelength region is added to provide an infrared cut capability, and a spectral filter is provided on the front surface of the image sensor body. A color image pickup device in which is arranged is described.

As described above, in Patent Documents 1 and 2, the infrared cut filter is inserted into the optical system so as to cover the entire light receiving element such as a CMOS or CCD.
JP 2000-19322 A JP-A-63-73204

  The absorption type infrared cut filter has a thickness of about 1 to 3 mm in order to provide sufficient absorption of infrared rays. When an absorption type infrared cut filter is used for an image sensor, it is difficult to reduce the size of the image sensor including the optical system because of the thickness of the absorption type infrared cut filter.

  In addition, when an absorption type infrared cut filter is used, a process for incorporating the infrared cut filter into the lens system as a camera member is required, which makes it difficult to reduce manufacturing costs.

  The image sensors of Patent Document 1 and Patent Document 2 include an infrared cut filter that covers the entire front surface of the image sensor body. For this reason, infrared rays are cut for all the light receiving elements provided in the image sensor, and there may be a difference between observation by the light receiving element and human visual sensitivity.

  For example, in Patent Document 2, as shown in FIG. 2 and FIG. 10 of Patent Document 2, the infrared cut filter absorbs light having a human visible light wavelength range of 550 nm to 700 nm. For this reason, if infrared rays are cut with respect to all the light receiving elements provided in the image sensor, the sensitivity of green, particularly the sensitivity of red may be lowered.

  In recent years, demands for increasing the number of pixels have been increasing for image sensors, and the miniaturization of pixels has progressed. For this reason, the pixel pitch (distance between pixels) is about 3 μm, and is becoming around 2 μm.

  When the pixel pitch becomes a fine pixel near 2 μm, the area per pixel is reduced, so the amount of light incident on the light receiving element is reduced, the sensitivity of the light receiving element is lowered, and the image quality is lowered (a dark image is formed). There is a case.

  As described above, in order to color-separate the light coming from the observation target, the color filters of the three primary colors of red, green, and blue are arranged on the light incident side of the light receiving element.

  FIG. 23 is a graph showing an example of the spectral transmittance of the color filters of the three primary colors of red, green, and blue. As shown in the graph of FIG. 23, the peak portions of the blue and green transmittances are about 80%. If the transmittance of the color filter is low, the amount of light reaching the light receiving element is reduced accordingly, and the deterioration of image quality (dark image) is promoted.

  In the spectral sensitivity (SPD sensitivity) of a light receiving element such as a CMOS or CCD shown in FIG. 21, the light receiving element has a wide sensitivity region of approximately 400 nm to 1000 nm in terms of the wavelength of light. However, as shown in FIG. 21 described above, the light receiving element has high sensitivity in the vicinity of the red wavelength range (700 nm), but the sensitivity decreases as it goes to the short wavelength range. In the vicinity of the blue wavelength range (400 nm to 500 nm), the sensitivity is about half that of red.

  In the graph showing the spectral transmittance of the red, green, and blue color filters in FIG. 23, the transmittance of the blue color filter is lower than the transmittance of the green and red color filters.

  In view of the above, in an image pickup device having three primary color filters of red, green, and blue, the sensitivity of the light receiving device is low in the blue region, and the blue color filter is lower than the transmittance of the red and green color filters. It can be seen that the transmittance is lower. For this reason, in the conventional imaging device, the sensitivity of blue is lower than that of green and red, and it is difficult to accurately reproduce the color balance when viewed as the whole color.

  Further, as shown in the spectral transmittance of the absorption-type infrared cut filter in FIG. 22, the absorption-type infrared cut filter has a region that absorbs light even in a visible light wavelength region of approximately 550 nm to 700 nm. That is, the transmittance of the absorption infrared cut filter gradually decreases in the visible light wavelength region of 550 nm to 700 nm. This visible light wavelength region of 550 nm to 700 nm corresponds to the green and red light regions. Therefore, when the absorption type infrared cut filter is used for the image sensor, there is a problem that the sensitivity of red is lowered. That is, in an imaging device that cuts infrared rays with an absorption-type infrared cut filter, not only blue but also red color reproducibility may be impaired.

  Conventionally, a technique using a complementary color filter composed of yellow (Y), magenta (M), and cyan (C) has been proposed to cope with a decrease in the amount of light to the light receiving element.

  By using a yellow (Y) color filter, the combined light of red and green can be extracted. By using a magenta (M) color filter, the combined light of red and blue can be extracted. By using a cyan (C) color filter, combined light of green and blue can be extracted.

  Each of the complementary color filters transmits two colors of light, so that the transmittance is high.

  However, in order to extract light of the three primary colors of blue, green, and red from light that has passed through complementary color filters of yellow, magenta, and cyan, for example, blue = (cyan + magenta-yellow) / 2, green = (cyan + Yellow-Magenta) / 2, Red = (Magenta + Yellow-Cyan) / 2, etc. The three primary colors of red, green, and blue from each value observed by the light receiving element through a complementary color filter Since it is necessary to perform a complicated calculation for calculating a value corresponding to, it may be difficult to express a vivid color close to the primary color.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thin image sensor with good color balance and color reproducibility.

  Specific means taken for realizing the present invention will be described below.

  An image sensor according to an example of the present invention includes a filter used to extract a specific color component of incident light, and a light receiving element that observes the incident light via the filter. The filter includes a transparent filter and a yellow component. A yellow filter used for extraction; a red filter used for extraction of a red component; and a correction filter having transmission suppression characteristics in the visible light wavelength region and having transmission characteristics on the longer wavelength side than the visible light wavelength region.

  In the imaging device of the example of the present invention, the light receiving element includes an incident light receiving element that observes incident light via a transparent filter, a yellow light receiving element that observes incident light via a yellow filter, and an incident light via a red filter. And a red light receiving element for observing incident light via a correction filter.

  The imaging device of the example of the present invention is obtained by subtracting the observation result observed with the yellow light receiving element from the observation result observed with the incident light receiving element, and calculating means for obtaining the blue observation result, and the yellow light receiving element. Subtracts the observation result observed with the red light receiving element from the observation result obtained by subtracting the observation result observed with the correction light receiving element from the calculation means for obtaining the green observation result and the observation result observed with the red light receiving element. And an arithmetic means for obtaining a corrected red observation result.

The image sensor of the example of the present invention may further include a transparent flattening layer that covers the yellow filter, the red filter, and the correction filter, and the transparent filter may be formed of the transparent flattening layer.
The imaging element of the example of the present invention may further include a microlens for condensing light on the light receiving element, and the microlens may be formed of a transparent planarization layer.

  In the image pickup device of the example of the present invention, the correction filter may have transmission characteristics at substantially the same level (same or approximate) as the red filter on the longer wavelength side than the visible light wavelength range.

  In the image pickup device of the example of the present invention, the difference between the light transmittance of the correction filter and the light transmittance of the red filter is in the range of approximately 5% in the light wavelength range of 400 nm to 550 nm and in the wavelength range longer than 750 nm. The correction filter may have a point at which the light transmittance is 50% in a region where the wavelength of light is approximately 630 nm to 750 nm.

  In the image sensor of the example of the present invention, the correction filter may be formed by optical superimposition of a plurality of colors.

  In the image sensor of the example of the present invention, the correction filter may be formed by optical superimposition of two colors of violet and red.

  In the image sensor of the example of the present invention, the correction filter may be formed by optical superimposition of two colors of cyan and red.

  In the imaging device of the example of the present invention, the correction filter may be formed by stacking a plurality of filters.

  The image pickup device of the example of the present invention may be configured such that a transparent filter, a yellow filter, a red filter, and a correction filter are adjacently arranged in a grid pattern to form a surface and form a unit of color separation. .

  In the imaging device of the example of the present invention, the transparent filter may have an ultraviolet absorption function for absorbing light in a wavelength region shorter than the visible light wavelength region.

  The imaging device of the example of the present invention may further include a light shielding film for suppressing reflection and transmission of light other than incident light that is incident on the light receiving device.

  In this case, the imaging device of the example of the present invention includes a substrate on which the light receiving element is arranged, and the light shielding film is on the incident light incident side of the substrate, and other regions except for a region where incident light is incident on the light receiving device May be provided.

  The image sensor of the example of the present invention may use a correction filter as the light shielding film.

  The imaging device of the example of the present invention may be formed by laminating a film having at least one of a near infrared absorption function and an ultraviolet absorption function on the light shielding film.

The image pickup device of the example of the present invention has a characteristic that the light transmittance rises at different wavelengths, has a transmission suppression characteristic for light on a shorter wavelength side than the rising part wavelength, and has a transmission suppression characteristic for light on a longer wavelength side than the rising part wavelength. A plurality of filters having transmission characteristics, a plurality of photoelectric conversion elements corresponding to each of the plurality of filters and receiving incident light through the plurality of filters, and observation of the plurality of photoelectric conversion elements observed through the plurality of filters Calculating means for performing subtraction processing based on observation data values observed via any two filters among the data values, and obtaining observation data values of light in a wavelength region corresponding to any two filter pairs; It comprises.
In the imaging device of the example of the present invention, the plurality of filters include a transparent filter, and further includes a transparent flattening layer that covers other filters other than the transparent filter, and the transparent filter is transparent flat. It may be formed by a chemical layer.
The image sensor of the example of the present invention may further include a microlens for condensing light on the light receiving element, and the microlens may be formed of a transparent planarization layer.
Further, in the image pickup device of the example of the present invention, the filter having the characteristic that the light transmittance rises on the longest wavelength side among the plurality of filters has a transmission suppression characteristic in the visible light wavelength region, and more than the visible light wavelength region. The correction filter may have a transmission characteristic on the long wavelength side.
Further, in the image pickup device of the example of the present invention, the filters other than the transparent filter and the correction filter among the plurality of filters have a point where the light transmittance is 50% in the region of the light wavelength of about 350 nm to 750 nm. However, when the wavelength of light is longer than about 750 nm, the light transmittance may be 90% or more.

  In the present invention, a decrease in blue sensitivity can be suppressed and the color balance can be improved. Further, in the present invention, it is possible to suppress red sensitivity reduction that occurs when an infrared cut filter is provided, and to improve red color reproducibility.

  In the present invention, it is possible to prevent an increase in the thickness of an optical system including a lens and the like, and to reduce the size of the image sensor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same elements are denoted by the same reference numerals and description thereof is omitted.

(First embodiment)
In the present embodiment, an image sensor that includes a light receiving element such as a CMOS or a CCD and that provides a filter layer on the light incident side of the light receiving element and observes a color component to be observed will be described.

  FIG. 1 is a front view illustrating an example of an arrangement state of filters in the image sensor according to the present embodiment. In FIG. 1, an example of the state of the filter viewed from the light incident side is shown.

  FIG. 2 is a cross-sectional view showing an example of the image sensor according to the present embodiment. In FIG. 2, the II cross section of the said FIG. 1 is represented. In FIG. 2, the case where the light receiving element is a CMOS is shown as an example, but the same applies to the case where the light receiving element is a CCD. Hereinafter, the same applies to other cross-sectional views of the imaging device.

  The imaging device 1 according to the present embodiment includes a filter layer 2 used for extracting a specific color component from incident light, light receiving devices 3W, 3Y, 3R, and 3Blk that observe the incident light via the filter layer 2, A calculation unit 4 is provided.

  The filter layer 2 includes a transparent filter 2W, a yellow filter 2Y, a red filter 2R, and a correction filter 2Blk. One unit of color separation is formed by each one of the transparent filter 2W, the yellow filter 2Y, the red filter 2R, and the correction filter 2Blk. The transparent filter 2W, the yellow filter 2Y, the red filter 2R, and the correction filter 2Blk are adjacently arranged in a grid pattern to form a surface. Thereby, the transparent filter 2W, the yellow filter 2Y, the red filter 2R, and the correction filter 2Blk are appropriately arranged.

  The transparent filter 2W is preferably transmitted without absorbing light having a long wavelength of 400 nm or longer. For example, the transparent filter 2W is preferably a filter having a transmittance of 95% or more of light having a long wavelength of 400 nm or more with reference to transparent glass having a refractive index n of about 1.5.

  The yellow filter 2Y is a filter used for extracting a yellow component (light obtained by combining a red component and a green component) from incident light. The yellow filter 2Y is a complementary color filter. In general, a complementary color filter has higher light transmittance than a color filter of three primary colors of red, green, and blue.

  The red filter 2R is a red color filter used for extracting a red component of incident light. In general, the red color filter has higher transmittance than the blue color filter and the green color filter, which are other color filters of the three primary colors.

  The correction filter 2Blk is a filter that has transmission suppression characteristics in the visible light wavelength range and has transmission characteristics on the longer wavelength side than the visible light wavelength range, and the transmittance in the infrared range is higher than the transmittance in the visible wavelength range. Also has high characteristics. Since the correction filter 2Blk has a transmission suppression characteristic (low transmission characteristic) in the visible light wavelength region, the correction filter 2Blk looks black visually.

  In the present embodiment, the correction filter 2Blk is formed by optically superimposing violet (V) and red (R). As a specific method for realizing the optical superposition, a single piece of filter may be formed by mixing a violet color material and a red color material, and a violet filter and a red filter may be combined. You may laminate.

  The incident light receiving element 3W, the yellow light receiving element 3Y, the red light receiving element 3R, and the correction light receiving element 3Blk, which are light receiving elements, are disposed on the opposite side of the light incident side of the filter layer 2, and convert the received light into an electrical signal, Obtain observation data values.

  The incident light receiving element 3W is associated with the transparent filter 2W, and observes incident light via the transparent filter 2W.

  The yellow light receiving element 3Y is associated with the yellow filter 2Y and observes incident light via the yellow filter 2Y.

  The red light receiving element 3R is associated with the red filter 2R and observes incident light via the red filter 2R.

  The correction light receiving element 3Blk is associated with the correction filter 2Blk, and observes incident light via the correction filter 2Blk.

  A one-to-one combination of a light receiving element and a filter corresponds to a pixel.

  The computing unit 4 includes a blue computing unit 4B, a green computing unit 4G, and a red computing unit 4R. This calculation unit 4 is based on the observation data values Dw, Dy, Dr, Dblk from the incident light receiving element 3W, the yellow light receiving element 3Y, the red light receiving element 3R, and the correction light receiving element 3Blk, and the blue observation data value Db, green It has a function of obtaining the observation data value Dg and the corrected red observation data value HDr.

  The blue calculation unit 4B subtracts the observation data value Dy observed by the yellow light receiving element 3Y from the observation data value Dw observed by the incident light receiving element 3W, and obtains the blue observation data value Db (= Dw−Dy). Ask.

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

  The red calculation unit 4R subtracts the observation data value Dblk observed by the corrected light receiving element 3Blk from the observation data value Dr observed by the red light receiving element 3R, and corrects the corrected red observation data value HDr (= Dr−Dblk). )

  2 shows a cross section that crosses the red filter 2R and the correction filter 2Blk and also crosses the red light receiving element 3R and the correction light receiving element 3Blk. However, the same configuration is applied to a cross section crossing another filter and another light receiving element.

  On the light incident side of the semiconductor substrate 5, an incident light receiving element 3W, a yellow light receiving element 3Y, a red light receiving element 3R, and a correction light receiving element 3Blk are formed and arranged.

  A planarizing layer 6 is laminated on the light incident side surface of the semiconductor substrate 5 on which the incident light receiving element 3W, the yellow light receiving element 3Y, the red light receiving element 3R, and the correction light receiving element 3Blk are formed. Thereby, the transparent filter 2W, the yellow filter 2Y, the red filter 2R, and the correction filter 2Blk can be formed on a flat installation surface. Note that the smoothing layer 6 may be omitted in order to make the imaging device 1 thin.

  On the light incident side of the flattening layer 6, there are a transparent filter 2W, a yellow filter 2Y, a red filter 2R, and a correction filter 2Blk corresponding to the incident light receiving element 3W, the yellow light receiving element 3Y, the red light receiving element 3R, and the correction light receiving element 3Blk, respectively. Are arranged, and the filter layer 2 is formed.

  A resin layer (transparent smoothing layer) 7 is laminated on the light incident side of the filter layer 2.

  On the light incident side of the resin layer 7, a microlens 8 corresponding to the incident light receiving element 3W, the yellow light receiving element 3Y, the red light receiving element 3R, and the correction light receiving element 3Blk is provided. The microlens 8 is disposed above each transparent filter 2W, yellow filter 2Y, red filter 2R, and correction filter 2Blk so as to make a pair with each transparent filter 2W, yellow filter 2Y, red filter 2R, and correction filter 2Blk. Yes. The microlens 8 is formed of an acrylic resin or the like, and improves the light condensing property to the incident light receiving element 3W, the yellow light receiving element 3Y, the red light receiving element 3R, and the correction light receiving element 3Blk.

  As described above, in FIG. 2, the single-layer correction filter 2Blk in which a red pigment and a violet pigment are mixed in a transparent resin is used. However, the correction filter 2Blk is not limited to the structure shown in FIG. 2 and may be realized by optical superposition. The optical superposition here may be realized in a single layer by a colored resin in which color materials (pigments, pigments) constituting color filters of different colors as shown in FIG. 2 are mixed. As shown, it may be realized by a laminated structure of color filters of two or more different colors. Further, two or more color materials may be used for color and transmittance adjustment.

  Thus, by optically superimposing two or more color filters, the transmittance of the correction filter 2Blk is the product of the transmittances of the respective color filters to be superimposed. Therefore, as in the present embodiment, by forming the correction filter 2Blk by optical superposition, the correction filter has transmission suppression characteristics in the visible light wavelength range and transmission characteristics on the longer wavelength side than the visible light wavelength range. 2Blk can be created.

  In FIG. 3, a correction filter 2Blk is configured by stacking a violet filter 2V and a red filter 2R as two or more types of filters.

  In the present embodiment, the 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 correction filter 2Blk) is 2.6 μm.

  The flattening layer 6 is formed of a thermosetting acrylic resin to which an ultraviolet absorber is added, and the film thickness is 0.3 μm. Here, the UV absorber is added to the planarizing layer 6 when a color filter is formed by a known photolithography method such as pattern exposure to the photosensitive resin layer and development using an alkaline solution. In addition, it is to form a filter having a good shape by preventing halation from the semiconductor substrate 5 as a base.

  In the present embodiment, the planarization layer 6 is formed. However, the planarization layer 6 may be omitted for the purpose of further thinning the imaging element.

  In the present embodiment, the transparent filter 2W is formed of an alkali-soluble photosensitive acrylic resin (refractive index n = 1.55) with a film thickness of about 1 μm.

  The yellow filter 2Y, the red filter 2R, and the correction filter 2Blk are formed using a colored photosensitive resin solution in which a color material (pigment, pigment) is attached to a transparent resin. Note that the transparent filter 2W may be formed of a transparent resin to which no coloring matter is added.

  In the present embodiment, the yellow filter 2Y, the red filter 2R, and the correction filter 2Blk, which are color filters, add and disperse a predetermined organic pigment to the transparent resin (photosensitive acrylic resin) used to form the transparent filter 2W. It is made of colored photosensitive resin.

  For example, as the organic pigment used for forming the yellow filter 2Y, for example, C.I. Pigment Yellow 150 is used. Alternatively, a mixed pigment in which C.I. Pigment Yellow 150 is mixed with C.I. Pigment Yellow 139 may be used.

  As the organic pigment used for forming the red filter 2R, for example, a mixture of C.I. Pigment Red 177, C.I. Pigment Red 48: 1, and C.I. Pigment Yellow 139 is used.

  Examples of the organic pigment used for forming the correction filter 2Blk include CIPigment Violet 23, and organic pigments used for the red filter 2R (for example, CIPigment Red 177, CIPigment Red 48: 1, and CIPigment Yellow 139 Is used.

  FIG. 4 is a graph showing an example of the spectral transmittance for the transparent filter 2W, the yellow filter 2Y, the red filter 2R, and the correction filter 2Blk.

  The imaging device 1 performs an operation (subtraction) based on the observation data values Dw, Dy, Dr, and Dblk by the respective light receiving elements, and obtains the observation data values Db, Dg, and HDr of the three primary colors of blue, green, and corrected red. obtain.

  That is, it can be considered that the imaging device 1 includes a blue filter, a green filter, and a red filter in appearance (virtually) by performing this calculation.

  FIG. 5 is a graph illustrating an example of the spectral transmittance of the apparent blue filter, green filter, and red filter obtained by the calculation of the image sensor 1.

  The apparent blue filter, green filter, and red filter of the imaging device 1 shown in FIG. 5 and the spectral transmittance of the conventional blue color filter, green color filter, and red color filter shown in FIG. In comparison with the rate, the spectral transmittance of the apparent blue filter, green filter, and red filter of the image sensor 1 has the following characteristics.

That is, the transmittance of the apparent blue filter and the green filter of the image sensor 1 has a characteristic that the transmittance is higher than that of the conventional blue color filter and the green color filter in the wavelength range of each color. The apparent transmittance of the blue filter is higher than that of the conventional blue color filter in the blue wavelength region. For this reason, in the imaging device 1, the sensitivity of blue is improved and the color balance is improved.

  The blue observation data value Db, the green observation data value Dg, and the corrected red observation data value HDr obtained by the image sensor 1 are calculated by subtracting the observation data values in the infrared region. For this reason, the spectral transmittance curves of the apparent blue filter, green filter, and red filter are suppressed in the infrared region in the spectral transmittance curves of the conventional blue color filter, green color filter, and red color filter. (Cut).

  Therefore, in the image sensor 1 according to the present embodiment, the infrared cut filter can be omitted and can be thinned. In addition, it is possible to prevent a reduction in red sensitivity that occurs when an absorption type infrared cut filter is provided, and it is possible to improve red color reproducibility.

  Hereinafter, the imaging device 1 according to the present embodiment and a conventional imaging device will be described in comparison.

  FIG. 6 is a graph showing an example of actual spectral characteristics of a conventional image sensor. The spectral characteristics of a conventional image sensor are considered to be equivalent to a product value obtained by multiplying the sensitivity of the light receiving element and the transmittance of a filter disposed on the light incident side of the light receiving element.

  As shown in FIG. 6, the blue color filter in the conventional image sensor has a lower transmittance than the other green and red color filters, and the sensitivity of the light receiving element in the blue wavelength region is the other green and red. Lower than the sensitivity in the red wavelength range. For this reason, in the conventional image sensor, there is a problem that blue / green is too smaller than red / green in the sensitivity ratio, and color reproducibility is lowered.

  On the other hand, the image sensor 1 in the present embodiment includes a transparent filter 2W, a yellow filter 2Y, a red filter 2R, and a correction filter 2Blk instead of the three primary colors blue, green, and red color filters. .

  For this reason, the spectral characteristics of the image sensor 1 in the present embodiment are the sensitivity of the light receiving element and the transparent filter 2W, yellow filter 2Y, red filter 2R, and correction filter 2Blk arranged on the light incident side of the light receiving element. It is considered equivalent to the product value multiplied by the transmittance.

  The transmittances of the transparent filter 2W, the yellow filter 2Y, and the red filter 2R are higher than those of the blue color filter and the green color filter. Therefore, the observed data values Dw and Dy observed by the incident light receiving element 3W, the yellow light receiving element 3Y, the red light receiving element 3R, and the correction light receiving element 3Blk via the transparent filter 2W, the yellow filter 2Y, the red filter 2R, and the correction filter 2Blk. , Dr, Dblk, the observed data values Db, Dg, HDr can be said to be observation results obtained with high transmittance.

  In particular, the blue observation data value Db is equivalent to that observed at a high light intensity, the blue / green sensitivity ratio can be increased, and the color reproducibility can be improved.

  Furthermore, in the present embodiment, the blue observation data value Db, the green observation data value Dg, and the corrected red observation data value HDr can be obtained by performing a simple operation of subtraction once. Therefore, the calculation can be simplified as compared with an image pickup device using a conventional complementary color filter, and a vivid color close to the primary color can be expressed.

  In the conventional imaging device, the light receiving device observes light in the infrared region, and the accuracy of the observation result may be reduced.

  On the other hand, in the present embodiment, the observation of the yellow light receiving element 3Y from the observation data value Dw of the incident light receiving element 3W, the observation data value Dy of the yellow light receiving element 3Y, and the observation data value Dr of the red light receiving element 3R, respectively. Since the data value Dy, the observation data value Dr of the red light receiving element 3R, and the observation data value Dblk of the corrected light receiving element 3Blk are subtracted, the observation results in the infrared region of each light receiving element are canceled (removed), The blue observation data value Db, the green observation data value Dg, and the corrected red observation data value HDr with reduced influence can be obtained, and the infrared cut filter is eliminated from the configuration of the image pickup device, thereby reducing the thickness. Can do.

  As shown in FIG. 6, the light receiving element generates a slight current even when light is not incident. The current that flows from the light receiving element even though such light is not incident is called a dark current and causes noise. Conventional color filters of the three primary colors of red, green, and blue have a wavelength range that transmits light in a predetermined wavelength range and blocks light in terms of spectral characteristics. However, the light receiving element generates dark current even in a wavelength region where light is blocked. For this reason, the observation result of the conventional image sensor includes noise due to dark current in addition to the observation result of light in the wavelength range where light is transmitted, and this noise may reduce the color reproducibility. .

  On the other hand, as described above, the imaging device 1 according to the present embodiment has the observation data value Dw of the incident light receiving element 3W, the observation data value Dy of the yellow light receiving element 3Y, and the observation data value of the red light receiving element 3R. Since the observation data value Dy of the yellow light receiving element 3Y, the observation data value Dr of the red light receiving element 3R, and the observation data value Dblk of the correction light receiving element 3Blk are subtracted from Dr, the dark current value is canceled out, and noise is obtained from the observation result. Can be removed. Thereby, color reproducibility can be improved.

  As shown in FIG. 6, the spectral transmittance of the conventional red, green, and blue color filters is as low as several percent at the bottom of the spectral curve of the blue and red color filters. The transmittance at the bottom of the spectral curve is as high as about 10%. Thus, it is said that the float of a spectrum is large that the transmittance | permeability of a skirt part is high.

  In the conventional image sensor, the base of the spectral curve of the green color filter exists in the blue and red wavelength ranges, and the spectrum of the green base is large, so blue and red are mixed in the green observation result. As a result, there is a problem that the reproducibility of green color is lowered.

  On the other hand, in the imaging device 1 according to the present embodiment, as described above, the observation data value Dw of the incident light receiving element 3W, the observation data value Dy of the yellow light receiving element 3Y, and the observation data value of the red light receiving element 3R. Since the observed data value Dy of the yellow light receiving element 3Y, the observed data value Dr of the red light receiving element 3R, and the observed data value Dblk of the corrected light receiving element 3Blk are subtracted from Dr, the float of the spectrum can be reduced, and color reproduction Can be improved.

  Hereinafter, the spectral characteristics of the correction filter 2Blk will be described.

  FIG. 7 is a graph showing an example of the spectral characteristics of the correction filter 2Blk.

  The transmittance of the correction filter 2Blk is substantially the same level (same or approximate) as the transmittance of the red filter 2R in FIG. 4 on the longer wavelength side than the visible light wavelength region.

  FIG. 7 shows a correction formed using an acrylic resin film having a thickness of 1.4 μm by mixing and dispersing a violet pigment (for example, CIPigment Violet 23) and a pigment used for forming the red filter 2R. The spectral characteristics of the filter 2Blk are shown.

  The correction filter 2Blk may be a combination in which a yellow pigment used for a yellow filter is mixed with violet, or a combination in which a red pigment is further added thereto.

  By subtracting the observation data value Dblk observed by the correction light receiving element 3Blk from the observation data value Dr observed by the red light receiving element 3R, the observation result in the infrared region from the observation data value Dr observed by the red light receiving element 3R Therefore, the correction filter 2Blk serves as an infrared cut filter for the red observation data value.

  The correction filter 2Blk shown in FIG. 7 has a low transmittance around 600 nm to 650 nm (effective transmittance as an infrared cut filter) unlike the general absorption infrared cut filter shown in FIG. The color rendering properties of red obtained after the calculation (subtraction) can be further improved.

  In the present embodiment, the transmittance of the correction filter 2Blk is a difference within 5% from the transmittance of the red color filter shown in FIG. 23 in the wavelength range of light of about 400 nm to 550 nm and the wavelength range of 750 nm and after. Suppose.

  As a result, it is possible to obtain a corrected red observation data value HDr that is not affected by infrared rays or other colors, and the red color reproducibility is improved.

  When the wavelength changes from 400 nm to 800 nm, the transmittance of the correction filter 2Blk maintains a low value from approximately 400 nm to 630 nm, but then rises rapidly from 630 nm to 750 nm, and then increases to a value exceeding 750 nm. To maintain.

  In the conventional absorption-type infrared cut filter, the wavelength at which the transmittance becomes a half value (50%) is about 630 nm. In the conventional infrared cut filter of an inorganic multilayer film, the wavelength at which the transmittance becomes half value is approximately 700 nm. In the correction filter 2Blk by optical superimposition of violet and red, the wavelength at which the transmittance becomes half value is approximately between 650 nm and 660 nm. In the correction filter 2Blk by the optical superimposition of cyan and red, the wavelength at which the transmittance becomes half value is between about 740 nm and 750 nm.

  From the above viewpoint, from the viewpoint of improving the accuracy of the red observation data value, the wavelength of the point P at which the transmission value becomes half value in the correction filter 2Blk is included in the wavelength region between 630 nm and 750 nm. desirable. And it is desirable to add the ultraviolet absorber to the transparent filter 2W.

  In the imaging device 1 according to the present embodiment, the corrected red observation data value HDr is obtained by the red observation data value Dr−correction observation data value Dblk. Accordingly, by making the light transmittance of the correction filter 2Blk as shown in FIG. 7, the corrected red observation data value HDr can be prevented from being influenced by infrared rays and other colors of light. In addition, it is possible to obtain the image sensor 1 having high red sensitivity and good red color reproducibility.

  In the present embodiment, as described above, the correction filter 2Blk may be configured by optical superimposition of two colors of violet and red, for example, and is configured by optical superimposition of two colors of cyan and red. It is good. By forming the correction filter 2Blk by combining these two colors, the wavelength position at which the light transmittance of the correction filter 2Blk becomes half value can be adjusted by the ratio of the color material, and further, the corrected red observation Color adjustment can be performed on the data value HDr.

  Further, color adjustment (for example, gray level adjustment) in the visible light wavelength range of the correction filter 2Blk, the rise of the transmission curve in the near-infrared transmission spectrum of 700 nm or 700 nm or later of the correction filter 2Blk, and the transmittance at half value. The wavelength position to be adjusted may be adjusted by adding other color materials or organic pigments of other colors, for example, organic pigments such as violet, blue, and green.

  In addition, light receiving elements such as CMOS and CCD have some sensitivity even in the ultraviolet region that humans do not feel. For this reason, it is desirable that the transparent filter 2W according to the present embodiment does not transmit light having a wavelength of 400 nm or less, and mainly allows light having a wavelength of 400 nm or less to pass without being absorbed.

  Therefore, an ultraviolet absorber, a photoinitiator or curing agent used for curing the resin, may be attached to the transparent filter 2W according to the present embodiment, and an ultraviolet absorbing function may be added to the transparent filter 2W.

  As the ultraviolet absorber, for example, benzotriazole compounds, benzophenone compounds, salicylic acid chemicals, and coumarin compounds can be used. Further, for example, a light stabilizer such as a hindered amine compound, a quencher or the like may be added to the ultraviolet absorber. In addition, an infrared absorbing compound or an infrared absorbing agent may be added to the resin constituting the transparent filter 2W, and a pendant (reactive dye or the like incorporated into the resin molecular chain in the form of a reactive infrared absorbing agent) is used. You may add to resin which comprises the transparent filter 2W.

  In the image pickup device 1 according to the present embodiment described above, it is possible to obtain the same effect as when the high-transmission blue, green, and red filters are provided. In particular, the image pickup device 1 is more blue than the conventional image pickup device. , The red observation accuracy can be improved.

  In the image sensor 1 according to the present embodiment, the observation result of the light in the infrared region that is not the human visible region can be deleted, and the photographing result close to the human visual sense can be obtained.

  Further, in the imaging device 1 according to the present embodiment, unlike the case of using a general absorption-type infrared cut filter having the transmission characteristics shown in FIG. 22, the absorption of light in the wavelength region of 550 nm to 650 nm is relaxed. Therefore, the color rendering property of red can be improved.

  In this embodiment, the infrared absorption function is realized by observing light in the infrared region with the correction pixel of the image sensor and subtracting the observation result of the correction pixel from the observation result of the red pixel. ing. In addition, for other colors (blue and green), the observation results with the infrared region drawn can be obtained. As a result, the infrared absorption type infrared cut filter provided in the optical system of the conventional camera module can be omitted, and the camera can be thinned.

(Second Embodiment)
In the present embodiment, a modified example of the image sensor according to the first embodiment will be described. Note that the imaging element according to the present embodiment includes the transparent filter 2W and the resin layer 7 in an integrated configuration in the imaging element 1 according to the first embodiment.

  FIG. 8 is a front view showing an example of the arrangement state of the filters in the image sensor according to the present embodiment. In FIG. 8, an example of the state of the filter layer portion viewed from the light incident side is shown.

  FIG. 9 is a cross-sectional view illustrating an example of the image sensor according to the present embodiment. In FIG. 9, the II-II cross section of FIG. 8 is shown.

  The transparent filter 10W of the image sensor 9 according to the present embodiment corresponds to the transparent filter 2W and the resin layer 7 of the first embodiment.

  In the image sensor 9 according to the present embodiment, a part of the transparent filter 10W is disposed 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, the red filter 2R, and the correction filter 3Blk.

  That is, the transparent filter 10W according to the present embodiment has a configuration in which the transparent filter 2W according to the first embodiment and the resin layer 7 are integrated, and also serves as a transparent smoothing layer.

  The image sensor 9 includes a transparent filter 10W, a yellow filter 2Y, a red filter 2R, and a correction filter 2Blk. The correction filter 2Blk according to the present embodiment is formed by optically superimposing violet and red. In FIG. 9, the correction filter 2Blk is formed of a single layer of a colored resin in which a violet pigment and a red pigment are mixed.

  The incident light receiving element 3W, the yellow light receiving element 3Y, the red light receiving element 3R, and the correction light receiving element 3Blk receive light that has passed through the transparent filter 10W, the yellow filter 2Y, the red filter 2R, and the correction filter 2Blk, respectively, and convert them into electrical signals. .

  Similar to the first embodiment, the image sensor 9 performs an operation (subtraction) based on the observation data values Dw, Dy, Dr, and Dblk from the respective light receiving elements, and performs blue, green, and corrected red 3 The observation data values Db, Dg, and HDr for the primary colors are obtained.

  That is, the imaging device 9 is assumed to have a blue filter, a green filter, and a red filter in appearance (virtually) by performing calculation (subtraction) based on the observation data value by each light receiving element. Is possible.

  An example of the spectral transmittance of wavelengths 400 nm to 800 nm for the apparent blue filter, green filter, and red filter obtained by the calculation of the image sensor 9 is the same as in FIG.

  The apparent transmittance of the blue filter and the green filter of the image sensor 9 is characterized in that the transmittance is higher than that of the conventional blue color filter and green color filter in the wavelength range of each color.

  In the present embodiment described above, the light incident side surfaces of the yellow filter 2Y, the red filter 2R, and the correction filter 2Blk are covered with the transparent filter 10W, and the transparent filter 10W and the transparent smoothing layer are integrated. .

  Thereby, the formation process of the transparent filter 10W and the transparent smoothing layer can be integrated, and it is not necessary to provide the pattern formation process of the transparent filter independently in the formation of the filter, and the manufacturing process of the image sensor 9 It can be simplified.

  That is, in this embodiment, after forming the yellow filter 2Y, the red filter 2R, and the correction filter 2Blk, the transparent filter 10W that is a transparent flattening layer is formed so as to cover these filters. In the present embodiment, a part of the transparent filter 10W, which is a transparent flattening layer, is disposed in the portion where the transparent filter 2W is formed in the first embodiment, and the transparent filter 10W is used as the transparent flattening layer. To play a role.

  Thereby, in the present embodiment, for example, a step of forming a transparent filter uniquely by a technique such as a photolithography method can be omitted, and a filter for four colors can be configured with the effort of forming a filter for three colors. The color filter forming process can be reduced.

(Third embodiment)
In the present embodiment, a modification of the image sensor according to the first and second embodiments will be described. Note that the image pickup device according to the present embodiment has the transparent filter 10W and the microlens 8 integrally formed in the image pickup device 9 according to the second embodiment.

  FIG. 10 is a cross-sectional view illustrating an example of an image sensor according to the present embodiment.

  The image sensor 11 according to the present embodiment includes a transparent filter 12W in which the microlens 8 and the transparent filter 10W of the image sensor 9 according to the second embodiment are integrated. That is, the transparent filter 12W also has a function of improving the light condensing property to the incident light receiving element 3W, the yellow light receiving element 3Y, the red light receiving element 3R, and the correction light receiving element 3Blk.

  Below, the manufacturing process of this image pick-up element 11 is demonstrated.

  FIG. 11 is a cross-sectional view showing an example of the first step of the manufacturing process of the image sensor 11 according to the present embodiment.

  First, the planarizing layer 6 made of a transparent resin is applied and formed on the semiconductor substrate 5 on which the incident light receiving element 3W, the yellow light receiving element 3Y, the red light receiving element 3R, and the correction light receiving element 3Blk are formed.

  In the formation of a color filter made of a photosensitive resin using a photolithographic method, pattern exposure to the photosensitive resin uses ultraviolet rays. Therefore, in order to prevent halation during pattern exposure, ultraviolet rays are applied to the planarizing layer 6. An absorbent may be added.

  FIG. 12 is a cross-sectional view illustrating an example of a second step of the manufacturing process of the image sensor 11.

  By the photolithography method, the yellow filter 2Y, the red filter 2R, and the correction filter 2Blk in which violet and red are optically superimposed are formed on the planarizing layer 6 in this order.

  The film thickness of each filter was 1.4 μm, the pixel pitch of each filter was 2.6 μm, and the average film thickness of the planarizing layer 6 was 0.1 μm. Note that the smoothing layer 6 may be omitted in order to make the imaging device 11 thinner.

  FIG. 13 is a cross-sectional view illustrating an example of a third step in the manufacturing process of the image sensor 11.

  On the semiconductor substrate 5 on which the yellow filter 2Y, the red filter 2R, and the correction filter 2Blk are formed, a thermosetting acrylic resin having a flattening function and containing 2% of a coumarin-based ultraviolet absorber is an average film thickness. It is applied at 2 μm, heated at 180 degrees for 3 minutes, the applied resin layer is cured, and a transparent filter 12W is formed.

  Further, in the third step, a photosensitive phenol resin 13 having a heat flow property (fluidized and rounded by heat treatment) and capable of an alkaline phenomenon is applied on the transparent filter 12W.

  FIG. 14 is a cross-sectional view illustrating an example of a fourth step in the manufacturing process of the image sensor 11.

  The said photosensitive phenol resin 13 is made into a predetermined pattern (for example, rectangular pattern) using the photolithographic method. Next, heating is performed at 200 degrees to fluidize the photosensitive phenol resin 13 having a predetermined pattern, thereby forming a hemispherical lens matrix 13a having a thickness of about 0.6 μm.

  FIG. 15 is a cross-sectional view illustrating an example of a fifth step of the manufacturing process of the image sensor 11.

  Anisotropic etching is performed on the transparent filter 12W in a dry etching apparatus. This etching eliminates the lens matrix 13a, but this lens matrix 13a serves as a mask for the transparent filter 12W, and the hemispherical shape of the lens matrix 13a is transferred to the transparent filter 12W.

  Thereby, it is possible to obtain the imaging device 11 that functions as a microlens and includes the transparent filter 12 </ b> W provided on each filter.

  As described above, the transparent filter 12W according to the present embodiment is integrated with the microlens. Thereby, the image pick-up element 11 can be made thin.

  In the present embodiment, the transparent filter 12W serving as a transparent flattening layer has a microlens shape, but the transparent filter 12W serving as a transparent flattening layer remains without forming a microlens. But you can.

  In this case, after forming the transparent filter 12W in the third step of FIG. 13, the imaging element can be obtained without performing subsequent steps such as formation of the photosensitive phenol resin 13.

  Here, as described above, it is preferable that an ultraviolet absorber is added to the planarizing layer 6 in order to prevent halation during pattern exposure of the photosensitive resin. Moreover, in order to prevent the generation | occurrence | production of the noise by the ultraviolet-ray based on a light receiving element having a sensitivity in an ultraviolet region, it is preferable to add an ultraviolet absorber to the transparent filter 12W.

  A functional group having an ultraviolet absorption function may be added to the polymer, monomer, or curing agent of the resin used for forming the transparent filter 12W by a pendant system, or a group that may be incorporated into the polymer may be polymerized. For example, quinones and anthracene may be introduced into the polymer, or a monomer having an ultraviolet absorbing group may be added.

  As the ultraviolet absorber, fine particles made of a metal oxide such as cerium oxide or titanium oxide can be used. However, as described above, in the case where the lens shape is transferred to the transparent filter 12W and the transparent filter 12W is a transfer type microlens, when an ultraviolet absorber is not added, an inorganic material is contained in the resin of the transfer lens. May become an optical foreign matter and light may be blocked. In this case, a black portion is generated in the image obtained by the image sensor 11. Therefore, it is preferable to use a dye-based ultraviolet absorber. For example, as the ultraviolet absorber, benzotriazole, benzophenone, triazine, salicylate, coumarin, xanthene, methoxycinnamic acid organic compounds and the like are used.

  In each of the above embodiments, yellow may be a common color of red and a correction color. That is, except for the transparent portion, yellow may be included in common in the red portion and the correction color portion, and may be used as a subtracting color for other color portions except for the transparent portion. In this case, for example, the yellow filter 2Y is formed at the yellow formation position with the yellow resin, and at the same time, the yellow filter 2Y is formed at the red formation position and the correction color formation position, and then the red filter is formed at the red formation position. The image sensor may be formed by forming the filter 2R and laminating the correction filter 2Blk at the correction color forming position.

(Fourth embodiment)
In this embodiment, a light-shielding film that suppresses reflection of light other than light incident on the light receiving element out of incident light, diffusion of long-wavelength light typified by infrared light, and wraparound is provided on the substrate. An image sensor provided in a region other than the region where the incident light is incident on the light receiving element on the light incident side will be described.

  FIG. 16 is a front view showing a first example of the arrangement position of the light shielding film of the image sensor according to the present embodiment.

  The image pickup device 17 shown in FIG. 16 is on the light incident side of the light receiving device, and reflects light on the outer peripheral portion of an effective pixel portion where various filters 18 such as a color filter, a correction filter, and a transparent filter are installed. A light shielding film 19 that suppresses transmission due to light diffusion and wraparound is provided. The imaging element 17 includes an electrode unit 20 for electrical connection with the outside, but no light shielding film is formed on the electrode unit 20.

  The light-shielding film 19 can use the correction filter described in the above embodiments.

  Disposing the light shielding film 19 on the outer periphery of the effective pixel portion of the image sensor 17 is effective in that the observation result of the image sensor 17 can be prevented from being affected by noise and the image quality can be improved. It is. In particular, by using the above-described various correction filters as the light shielding film 19, light in the visible light wavelength region can be cut, and stray light in the frame portion (outer peripheral portion) of the image sensor 17 can be reduced.

  FIG. 17 is a cross-sectional view showing an example of the image sensor 17 according to the present embodiment. In FIG. 17, the III-III cross section of FIG. 16 is shown.

  A CMOS is provided as the light receiving element 3 on the light incident side of the semiconductor substrate 5 of the imaging element 17. Various filters 18 such as a color filter, a correction filter, and a transparent filter are disposed on the light incident side of the light receiving element 3 via the planarization layer 6. Further, the microlens 8 is provided for each pixel on the light incident side of the various filters 18.

  An electrode portion 20 is formed on the frame portion on the light incident side of the semiconductor substrate 5, and a light shielding film 19 is formed on a portion excluding the electrode portion 20. As the electrode unit 20, for example, an Al pad can be used. The electrode unit 20 performs electrical connection between the outside and the image sensor 17. The light shielding film 19 is not formed on the electrode portion 20.

  One of the purposes of the present embodiment is to omit the infrared cut filter. Therefore, it is preferable that the light shielding film 19 has a function of cutting infrared light in addition to a function of cutting visible light. As an example of such a light-shielding film that cuts visible light and infrared light, there is a light-shielding film in which a black pigment such as carbon black is used at a solid ratio of 40%. The thickness of the light-shielding film in which the black pigment such as carbon black is 40% in solid ratio can be set to 0.8 μm, for example.

  FIG. 18 is a cross-sectional view showing a second example of the arrangement position of the light shielding film of the image sensor according to the present embodiment.

  The image pickup device 14 shown in FIG. 18 has the same configuration as the image pickup device 17, but a light shielding film on the outer periphery of the light receiving device 3 of the CMOS among the light incident side surfaces of the semiconductor substrate 5 and the smoothing layer 6. 15 and film 16 are laminated.

  As the light shielding film 15, for example, a correction filter 2Blk can be used. That is, the light shielding film 15 can be formed with the same material and configuration as the correction filter 2Blk by the same method as the method of forming the correction filter 2Blk.

  The imaging element 14 is on the semiconductor substrate 5 and a light shielding film 15 (correction filter 2W) having transmission suppression characteristics in the visible light wavelength region is disposed outside the opening of the light receiving element.

  In a conventional image sensor, light incident on a portion other than the light receiving element may stray in the image sensor and become stray light. This stray light then becomes noise when it enters the light receiving element. Further, when unnecessary light is incident on the peripheral area of the light receiving element, it causes noise.

  However, in the present embodiment, the light shielding film 15 having a transmission suppressing characteristic in the visible light wavelength region is disposed around the effective opening of the light receiving element and part of the semiconductor substrate 5 (for example, the outer periphery of the semiconductor substrate 5). Therefore, the light incident on the other part except the light receiving element is absorbed by the light shielding film 15.

  Thereby, stray light and unnecessary light can be prevented from entering the light receiving element, noise can be reduced, and the image quality obtained by the imaging element 14 can be improved. In particular, when the correction filter 2W is used as the light shielding film 15, light in the visible light wavelength region can be cut, stray light generated around the imaging element 14 can be reduced, and noise generation from the periphery of the light receiving element can be reduced. .

  When the correction filter 2W is used as the light shielding film 15, the light shielding film 15 transmits infrared light and ultraviolet light. Therefore, in the present embodiment, a light shielding film 15 is disposed on a portion of the semiconductor substrate 5 that is not an effective opening of the light receiving element, and a film 16 that absorbs infrared rays and ultraviolet rays is laminated on the light shielding film 15. .

  By using a resin in which an infrared absorber and an ultraviolet absorber are added to the transparent resin used to form the microlens 8, the material cost can be reduced for the film 16.

  As a result, it is possible to prevent infrared rays and ultraviolet rays incident on a portion that is not a light receiving element from straying, becoming stray light, and generating noise.

  In this embodiment, a light shielding film is provided on the outer periphery of the effective pixel portion. However, when the light receiving element is a CCD, a light shielding film may be formed on the wiring portion.

(Fifth embodiment)
In the present embodiment, the transmittance of a plurality of filters including a color filter, a correction filter, and a transparent filter rises (increases) in different wavelength ranges.

  FIG. 19 is a front view showing an example of an image sensor according to the present embodiment. FIG. 19 illustrates an example of the state of the filters F1 to F7 of the image sensor 21 as viewed from the light incident side. The filters F1 to F7 include a color filter, a correction filter, and a transparent filter.

  The light receiving elements (photoelectric conversion elements) H1 to H7 receive incident light via the filters F1 to F7, respectively, and output observation data values E1 to E7 to the calculation unit 22.

  The calculation unit 22 performs subtraction processing based on observation data values observed via any two filters among the observation data values E1 to E7 of the plurality of light receiving elements H1 to H7 observed via the filters F1 to F7. The observation data value of the light in the wavelength region corresponding to the arbitrary two filter pairs is obtained, and the calculated observation data value is output.

  FIG. 20 is a graph showing an example of the relationship between the wavelength of light and the transmittance of the filters F1 to F7 provided in the image sensor 21 according to the present embodiment.

  The plurality of filters F1 to F7 provided in the imaging device 21 according to the present embodiment have a characteristic of suppressing transmission of light on the shorter wavelength side than the wavelengths WL1 to WL7 of the portion where the own transmittance rises. It has a characteristic of transmitting light having a longer wavelength than the wavelengths WL1 to WL7 where self transmittance rises.

  In the image sensor 21, light incident through the filters F1 to F7 is observed by the light receiving elements (photoelectric conversion elements) H1 to H7, respectively. The calculation unit 22 inputs the observed data values E1 to E7 of the light receiving elements H1 to H7.

  The filters F1 to F7 have a substantially S-shaped spectral curve that has a low transmittance in a shorter wavelength region, a higher transmittance in a long wavelength region, and a substantially S-shaped transmittance that rises in a substantially S shape. Become. The filters F1 to F7 rise in transmittance in different wavelength ranges.

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

  The filter F3 is a yellow color filter used for extracting a yellow component of light.

  The filter F6 is a red color filter used for extracting a red component of light.

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

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

  Further, in the characteristics of light transmittance and wavelength, the wavelength WL4 of the portion where the transmittance of the filter F4 rises is the wavelength WL3 of the portion where the transmittance of the filter (yellow filter) F3 rises and the wavelength WL3 of the filter (red filter) F6. It is between the wavelength WL6 of the portion where the transmittance rises.

  Similarly, the wavelength WL5 of the part where the transmittance of the filter F5 rises is the wavelength WL3 of the part where the transmittance of the filter (yellow filter) F3 rises and the wavelength WL6 of the part where the transmittance of the filter (red filter) F6 rises. between.

  In the characteristics of light transmittance and wavelength, it is assumed that the wavelength WL4 at the portion where the transmittance of the filter F4 rises increases on the shorter wavelength side than the wavelength WL5 at the portion where the transmittance of the filter F5 rises.

  For example, the wavelengths WL4 and WL5 where the transmittance of the filters F4 and F5 rises are the wavelength WL3 where the transmittance of the filter (yellow filter) F3 rises and the wavelengths where the transmittance of the filter (red filter) F6 rises. It is assumed that the wavelength region between WL6 is divided into three.

  As described above, the calculation unit 22 performs a subtraction process on the observation data values of the incident light observed via any two filters among the observation data values E1 to E7 of the incident light observed via the filters F1 to F7. The observation data value of the light in the wavelength region corresponding to the arbitrary two filter pairs is obtained.

  For example, the calculation unit 22 subtracts the observation data value E3 observed via the filter (yellow filter) F3 from the observation data value E1 observed via the filter (transparent filter) F1, and outputs a blue observation data value G1. To do.

  Further, for example, the calculation unit 22 subtracts the observation data value E6 observed via the filter (red filter) F6 from the observation data value E3 observed via the filter (yellow filter) F3, thereby obtaining a green observation data value G2. Is output.

  Further, for example, the calculation unit 22 subtracts the observation data value E7 observed via the correction filter F7 from the observation data value E6 observed via the filter (red filter) F6 to remove the influence (component) of infrared rays. The red observation data value G3 is output.

  Furthermore, the calculation part 22 can obtain | require the observation data value of a finer color by using filter F2, F4-F6.

  For example, the calculation unit 22 subtracts the observation data value E3 observed via the filter (yellow filter) F3 from the observation data value E2 observed via the filter F2, and outputs a green-observed blue observation data value G4. .

  For example, the calculation unit 22 subtracts the observation data value E4 observed via the filter F4 from the observation data value E3 observed via the filter (yellow filter) F3, and outputs a yellow-green observation data value G5.

  For example, the calculation unit 22 subtracts the observation data value E5 observed via the filter F5 from the observation data value E4 observed via the filter F4, and outputs a yellow observation data value G6.

  For example, the calculation unit 22 subtracts the observation data value E6 observed via the filter F6 (red filter) from the observation data value E5 observed via the filter F5, and outputs an orange observation data value G7.

  The transmittances of the filters F1 to F7 are preferably 90% or more when the wavelength of light is longer than 750 nm. This is because the light component in the infrared region is cut and the intensity of the light component in the human visible light wavelength region is observed with high accuracy.

  The light receiving elements (photoelectric conversion elements) H1 to H7 may have a difference in sensitivity in a short wavelength region for each manufacturer.

  When an ultraviolet absorber is added to the filter (transparent filter) F1, the wavelength of light at which the transmittance of the filter F1 is 50% is preferably between 350 nm and 400 nm (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, the wavelength of light at which the transmittance of the other filters F2 to F7 other than the filter F1 is 50% is 400 nm or more, and the transmittance of the filter F1 is It is preferably 90% or more when the wavelength of light is 400 nm or more.

  Thereby, the influence of the sensitivity difference of the light receiving elements H1 to H7 can be reduced, and the blue observation data value can be obtained under a certain condition.

  Further, the human visual sensitivity is approximately between 400 nm and 700 nm, and in order to adjust the sensitivity of the red region and adjust the observation data value of red, the transmittance of the filters F1 to F7 is 50%. The wavelength of the light is preferably 750 nm or less.

  From the above examination, when an ultraviolet absorber is added to the filter (transparent filter) F1, the plurality of filters F1 to F7 have a point that the light transmittance becomes 50% in the region of the light wavelength of about 350 nm to 750 nm. When the wavelength of light is longer than about 750 nm, the light transmittance is preferably 90% or more.

  Further, when an ultraviolet absorber is not added to the filter (transparent filter) F1, the plurality of filters F2 to F7 excluding the filter F1 have a point at which the light transmittance is 50% in the region of the light wavelength of 400 nm to 750 nm. And the light transmittance is 90% or more when the wavelength of light is longer than about 750 nm, and the filter F1 has a light transmittance of 90% or more in the region longer than the wavelength of light 400 nm. It is preferable to become.

  In the present embodiment, a microlens may be provided on the light incident side of the filters F1 to F7, and the filter F1 and the microlens may be formed of the same transparent resin.

  As described above, filters having different spectral characteristics (for example, F1 to F7) whose transmittance rapidly increases in different wavelength regions are appropriately selected, and the selected filters are arranged on the light receiving element, and obtained by the light receiving element. By performing the calculation based on the observation data, observation data values of other finer color components can be obtained in addition to red (R), green (G), and blue (B).

  It should be noted that a correction filter having a transmittance of 50% at a wavelength of about 660 nm can be obtained by preparing the correction filter according to each of the above embodiments by mixing a red pigment and a violet pigment.

  Further, by creating a correction filter by mixing a red pigment and a cyan pigment, a correction filter having a transmittance of 50% at a wavelength of about 740 nm can be obtained.

FIG. 3 is a front view illustrating an example of an arrangement state of filters in the image sensor according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating an example of an image sensor according to the first embodiment. Sectional drawing which shows the other example of the image pick-up element which concerns on 1st Embodiment. The graph which shows an example of the spectral transmittance about a transparent filter, a yellow filter, a red filter, and a correction filter. The graph which shows an example of the spectral transmittance about the apparent blue filter, green filter, and red filter obtained by the calculation of the image sensor according to the first embodiment. The graph which shows the example of the actual spectral characteristic of the conventional image pick-up element. 3 is a graph illustrating an example of spectral characteristics of a correction filter of the image sensor according to the first embodiment. The front view which shows an example of the arrangement state of the filter in the image pick-up element which concerns on the 2nd Embodiment of this invention. Sectional drawing which shows an example of the image pick-up element which concerns on 2nd Embodiment. Sectional drawing which shows an example of the image pick-up element which concerns on the 3rd Embodiment of this invention. Sectional drawing which shows the example of the 1st process of the manufacturing process of the image pick-up element which concerns on 3rd Embodiment. Sectional drawing which shows the example of the 2nd process of the manufacturing process of the image pick-up element which concerns on 3rd Embodiment. Sectional drawing which shows the example of the 3rd process of the manufacturing process of the image pick-up element which concerns on 3rd Embodiment. Sectional drawing which shows the example of the 4th process of the manufacturing process of the image pick-up element which concerns on 3rd Embodiment. Sectional drawing which shows the example of the 5th process of the manufacturing process of the image pick-up element which concerns on 3rd Embodiment. The front view which shows the 1st example of the arrangement position of the light shielding film of the image pick-up element which concerns on the 4th Embodiment of this invention. Sectional drawing which shows an example of the image pick-up element which concerns on 4th Embodiment. Sectional drawing which shows the 2nd example of the arrangement position of the light shielding film of the image pick-up element which concerns on 4th Embodiment. The front view which shows an example of the image pick-up element which concerns on the 5th Embodiment of this invention. The graph which shows the example of the relationship between the wavelength of the light of the filter with which the image sensor which concerns on 5th Embodiment is equipped, and the transmittance | permeability. The graph which shows the example of the relationship of the transmittance | permeability of a preferable near-infrared cut filter with respect to human visual sensitivity, the sensitivity of a light receiving element, and the sensitivity of a light receiving element. The graph which shows the example of the relationship between the wavelength of light and the transmittance | permeability in a reflection type infrared cut filter and an infrared absorption type infrared cut filter. The graph which shows an example of the spectral transmittance of the color filter of three primary colors of red, green, and blue.

Explanation of symbols

  1,9,11,14,17 ... image sensor, 2 ... filter layer, 2W, 10W, 12W ... transparent filter, 2Y ... yellow filter, 2R ... red filter, 2Blk ... correction filter, 2V ... violet filter, 3W ... Incident light receiving element 3W, 3Y ... yellow light receiving element, 3R ... red light receiving element, 3Blk ... corrected light receiving element, 4, 22 ... calculating unit, 4B ... blue calculating unit, 4G ... green calculating unit, 4R ... red calculating unit, 5 DESCRIPTION OF SYMBOLS ... Semiconductor substrate, 6 ... Planarization layer, 7 ... Resin layer, 8 ... Microlens, 13 ... Photosensitive phenol resin, 13a ... Lens matrix, 15, 19 ... Light-shielding film, 16 ... Film, 18 ... Filter, 20 ... Electrode part, 21 ... imaging device, H1-H7 ... light receiving device, F1-F7 ... filter

Claims (18)

In an imaging device comprising a filter used to extract a specific color component of incident light and a light receiving element that observes the incident light via the filter,
The filter is
A transparent filter,
A yellow filter used to extract the yellow component;
A red filter used to extract the red component;
A correction filter having transmission suppression characteristics in the visible light wavelength range, and having a transmission characteristic on the longer wavelength side than the visible light wavelength range,
Further comprising a transparent flattening layer covering the yellow filter, the red filter, and the correction filter;
The transparent filter and the transparent planarization layer are integrally formed ,
The transparent filter includes an ultraviolet absorber, and has an ultraviolet absorption function of absorbing light in a wavelength region shorter than the visible light wavelength region,
Each of the yellow filter, the red filter, and the correction filter has a characteristic that the light transmittance rises at a different wavelength, has a transmission suppression characteristic for light on a shorter wavelength side than the wavelength of the rising part, and has a wavelength of the rising part Has transmission characteristics for light on longer wavelengths,
An image sensor characterized by the above. The light receiving element is
An incident light receiving element for observing the incident light via the transparent filter;
A yellow light receiving element for observing the incident light via the yellow filter;
A red light receiving element for observing the incident light via the red filter;
A correction light receiving element for observing the incident light via the correction filter,
Subtracting the observation result observed by the yellow light receiving element from the observation result observed by the incident light receiving element, and calculating means for obtaining the blue observation result;
Subtracting the observation result observed by the red light receiving element from the observation result observed by the yellow light receiving element, and calculating means for obtaining a green observation result;
The imaging device according to claim 1 , further comprising: an arithmetic unit that subtracts the observation result observed with the correction light receiving element from the observation result observed with the red light receiving element to obtain a corrected red observation result. 3. The image sensor according to claim 1 , wherein the correction filter has substantially the same level of transmission characteristics as the red filter on the longer wavelength side than the visible light wavelength range. 4. The difference between the light transmittance of the correction filter and the light transmittance of the red filter is in the range of approximately 5% in the light wavelength region of 400 nm to 550 nm and in the wavelength region longer than 750 nm,
4. The image pickup device according to claim 1 , wherein the correction filter has a point at which the light transmittance is 50% in a region of a light wavelength of about 630 nm to 750 nm. 5. The correction filter is formed of a colored photosensitive resin in which an organic pigment is dispersed,
The organic pigment is C.I. I. Pigment Violet 23 and C.I. I. Pigment Red 177 and C.I. I. Pigment Red 48: 1 and C.I. I. The imaging device according to claim 1, wherein the image sensor is a mixture of Pigment Yellow 139. The image sensor according to claim 1 , wherein the correction filter is formed by optical superimposition of a plurality of colors.   The imaging device according to claim 6, wherein the correction filter is formed by optical superimposition of two colors of violet and red.   The image sensor according to claim 6, wherein the correction filter is formed by optical superimposition of two colors of cyan and red. The image sensor according to claim 1 , wherein the correction filter is formed by stacking a plurality of filters.   2. The transparent filter, the yellow filter, the red filter, and the correction filter are arranged adjacent to each other in a grid pattern to form a surface, thereby forming a unit of color separation. The imaging device according to claim 9. 11. The light-shielding film according to claim 1 , further comprising a light-shielding film for suppressing reflection and transmission of light other than light incident on the light receiving element among the incident light. Image sensor. Comprising a substrate on which the light receiving element is disposed;
The imaging device according to claim 11 , wherein the light shielding film is provided on an incident side of the incident light of the substrate, and is provided in a region other than a region where the incident light is incident on the light receiving device. The image pickup device according to claim 11 , wherein the correction filter is used as the light shielding film. The imaging device according to claim 11 , wherein a film having at least one of a near infrared absorption function and an ultraviolet absorption function is laminated on the light shielding film. A plurality of filters each having a characteristic that light transmittance rises at a different wavelength, a light transmission suppression characteristic for light on a shorter wavelength side than the rising part wavelength, and a transmission characteristic for light on a longer wavelength side than the rising part wavelength; ,
A plurality of photoelectric conversion elements corresponding to each of the plurality of filters and receiving incident light via the plurality of filters;
A subtraction process is executed based on observed data values observed via any two filters among the observed data values of the plurality of photoelectric conversion elements observed via the plurality of filters, and the arbitrary two filters Computing means for obtaining observation data values of light in the wavelength region corresponding to the pair of
The plurality of filters include a transparent filter;
Further comprising a transparent flattening layer that covers other filters of the plurality of filters excluding the transparent filter;
The transparent filter and the transparent planarization layer are integrally formed ,
The transparent filter includes an ultraviolet absorber and has an ultraviolet absorption function of absorbing light in a wavelength region shorter than the visible light wavelength region.
An image sensor characterized by the above. The filter having the characteristic that the light transmittance rises on the longest wavelength side among the plurality of filters has a transmission suppression characteristic in the visible light wavelength range, and a correction filter having a transmission characteristic on the longer wavelength side than the visible light wavelength range The image pickup device according to claim 15, wherein Among the plurality of filters, the filters other than the transparent filter and the correction filter have a point where the light transmittance is 50% in the region of the light wavelength of about 350 nm to 750 nm, and the light wavelength is about 750 nm. The image sensor according to claim 16 , wherein the light transmittance is 90% or more in the case of a longer wavelength side. The correction filter is formed of a colored photosensitive resin in which an organic pigment is dispersed,
The organic pigment is C.I. I. Pigment Violet 23 and C.I. I. Pigment Red 177 and C.I. I. Pigment Red 48: 1 and C.I. I. The image pickup device according to claim 16 or 17, which is a mixture of Pigment Yellow 139.

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