JP2008021736A - Optical sensor, filter, and filter manufacturing method - Google Patents

Abstract

An optical sensor in the infrared region with high productivity is provided.
An optical sensor includes a red filter formed on each light receiving element with a red organic pigment and a cyan organic pigment that transmits incident light in a shorter wavelength region than the red filter. A cyan filter 14Cy formed on the red filter 14R, a blue filter 14B selectively formed on the red filter 14R by a blue organic pigment that transmits incident light in a shorter wavelength region than the cyan filter 14Cy, and a cyan filter 14Cy Intensity obtained from the blue light receiving element 12B that receives the incident light that has passed through the blue filter 14B and the red filter 14R from the intensity value obtained from the cyan light receiving element 12Cy that receives the incident light that has passed through the red filter 14R. And an arithmetic unit 21 for subtracting values.
[Selection] Figure 1

Description

  The present invention relates to a highly productive infrared region optical sensor, filter, and filter manufacturing method.

  In recent years, optical sensors that detect light have been used in various fields. For example, an optical sensor that detects infrared rays is used for a length measuring means for a subject used in a single-lens reflex camera or the like, an in-vehicle camera, a surveillance camera, or the like.

  In the optical sensor, a filter that transmits light in a specific wavelength region such as infrared rays is formed on the light receiving element. Examples of the filter include an inorganic filter made of a multilayer thin film of an inorganic material, an organic pigment filter in which an organic pigment is dispersed, and the like.

Here, in the optical sensor in the infrared region, an inorganic filter with good wavelength selectivity is often used. The inorganic filter transmits light having a peak wavelength with high transmittance and reflects light in other wavelength regions. Therefore, in general, an inorganic filter has properties of high color purity and high luminance as compared with an organic pigment filter. An example of such an inorganic filter is one in which SiO ₂ and TiO ₂ are alternately laminated (see, for example, Patent Document 1).
JP-A-6-337310

  However, the above-described inorganic filter has lower productivity than the organic pigment filter for the following reasons.

  (A) When manufacturing an inorganic filter, it is necessary to use a vacuum evaporation apparatus. Therefore, it takes a long time to form a film. According to the study by the present inventors, it takes about 20 hours to perform chamber exhaust, vapor deposition, and cooling bend.

  (B) When an optical sensor is manufactured using an inorganic filter, when the inorganic filter becomes spectrally abnormal, reworking of removing the inorganic filter and manufacturing the inorganic filter again is impossible. For this reason, when a spectral abnormality occurs in the filter, the optical sensor itself is wasted.

(C) Since the inorganic filter forms a film of an inorganic material such as TiO ₂ by a vacuum deposition method, a crack is likely to occur in the multilayer thin film due to an external force such as bending. That is, since there is no flexibility, defects of several tens of μm often occur.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a highly productive infrared region optical sensor, filter, and filter manufacturing method.

  The present invention takes the following means in order to solve the above problems.

  The invention corresponding to claim 1 is formed of a substrate, a plurality of light receiving elements formed on the substrate for obtaining an intensity value of received incident light, and a red organic pigment on each of the light receiving elements. A red filter, a first filter selectively formed on the red filter by a first organic pigment that transmits incident light in a shorter wavelength region than the red filter, and a position at which the first filter is formed. A second filter selectively formed by a second organic pigment that transmits incident light in a shorter wavelength region than the first filter at a different position on the red filter, the first filter, and the red filter, Calculating means for subtracting the intensity value obtained from the light receiving element that receives the incident light that has passed through the second filter and the red filter from the intensity value obtained from the light receiving element that receives the incident light transmitted through the second filter; Light with It is a capacitor.

  According to a second aspect of the present invention, in the optical sensor according to the first aspect, the first filter is a cyan filter made of a cyan organic pigment, and the second filter is a blue light made of a blue organic pigment. An optical sensor that is a filter.

  According to a third aspect of the present invention, a substrate, a plurality of light receiving elements formed on the substrate for obtaining an intensity value of received incident light, and a red organic pigment are selectively formed on the light receiving elements. And a cyan organic pigment that transmits incident light in a shorter wavelength region than the red filter at a position on the light receiving element different from the position where the red filter is formed. A cyan filter and a blue organic pigment that transmits incident light in a shorter wavelength range than the cyan filter are selectively formed at a position on the light receiving element different from the positions at which the red filter and the cyan filter are formed. Based on intensity values obtained from light receiving elements that receive incident light transmitted through the blue filter and the red filter, the cyan filter, and the blue filter. A light sensor and an arithmetic means for calculating the intensity value.

  The invention corresponding to claim 4 is the first light receiving element and the second light receiving element formed on the substrate, the intensity value obtained from the first light receiving element, and the intensity value obtained from the second light receiving element, A filter for use in an optical sensor having a subtracting processing unit, wherein a red filter made of a red organic pigment and a cyan filter made of a cyan organic pigment are sequentially stacked on the first light receiving element. And a red filter made of a red organic pigment and a blue filter made of a blue organic pigment, which are sequentially stacked on the second light receiving element.

  The invention corresponding to claim 5 includes a red filter forming step of forming a red filter made of a red organic pigment on a plurality of light receiving elements formed on a substrate, and a wavelength shorter than that of the red filter on the red filter. A first filter forming step of selectively forming a first filter made of a first organic pigment that transmits incident light in a region, and a position on the red filter that is different from a position where the first filter is formed, And a second filter forming step of selectively forming a second filter made of a second organic pigment that transmits incident light in a shorter wavelength region than the first filter.

  The invention corresponding to claim 6 is the filter manufacturing method corresponding to claim 5, wherein the first filter is a cyan filter made of a cyan organic pigment, and the second filter is made of a blue organic pigment. It is a filter manufacturing method which is a blue filter.

<Terminology>
In the present invention, “transmittance” is determined by setting the transmittance of a transparent glass having a refractive index of around 1.5 as 100%.

  In addition, the “half-value wavelength” is a spectral characteristic curve in which the transmittance increases from the short wavelength side where the transmission of light is suppressed to the long wavelength side where the light is transmitted. It means wavelength. That is, the half-value wavelength in the spectral characteristic curve that is substantially S-shaped.

<Action>
Therefore, the present invention has the following effects by taking the above-described means.

  The invention corresponding to claim 1 is a red filter selectively formed on a red filter by a red filter formed on each light receiving element by a red organic pigment and a first organic pigment that transmits incident light in a shorter wavelength region than the red filter. A second filter selectively formed on the red filter by a second organic pigment that transmits incident light in a shorter wavelength region than the first filter, a first filter, and a red filter; Calculating means for subtracting the intensity value obtained from the light receiving element that receives the incident light transmitted through the second filter and the red filter from the intensity value obtained from the light receiving element that receives the incident light transmitted through the second filter. With this configuration, since the infrared transmission filter is formed using an organic pigment, an optical sensor in the infrared region with high productivity can be provided.

  The invention corresponding to claim 2 is the optical sensor according to claim 1, wherein the first filter is a cyan filter made of a cyan organic pigment, and the second filter is a blue filter made of a blue organic pigment. Therefore, an optical sensor that can detect infrared rays in a wavelength region of about 750 nm to about 800 nm can be provided.

  According to a third aspect of the present invention, there is provided a red filter selectively formed on a light receiving element by a red organic pigment, and a cyan organic pigment at a position on the light receiving element different from the position where the red filter is formed. A blue filter selectively formed with a blue organic pigment at a position on the light receiving element different from a position where the red filter and the cyan filter are formed, and a red filter and cyan. Based on the intensity value obtained from the light receiving element that receives the incident light that has passed through each of the filter and the blue filter, and a calculation means for calculating the intensity value of the light in the infrared region, approximately 750 nm to approximately 800 nm An optical sensor that detects infrared rays in the wavelength region can be provided.

  In the invention corresponding to claim 4, the first light receiving element and the second light receiving element formed on the substrate, the intensity value obtained from the first light receiving element, and the intensity value obtained from the second light receiving element are subtracted. And a red filter and a cyan filter that are sequentially stacked on the first light receiving element, and a red filter and a blue filter that are sequentially stacked on the second light receiving element, By the structure provided with, the filter which extracts the infrared rays of a wavelength range of about 750 nm-about 800 nm can be provided.

  According to a fifth aspect of the present invention, there is provided a red filter forming step in which a red filter made of a red organic pigment is individually formed on a plurality of light receiving elements formed on a substrate for each light receiving element; A first filter forming step of selectively forming, on the red filter, a first filter made of a first organic pigment that transmits incident light in a wavelength region; And a second filter forming step of selectively forming a second filter made of a second organic pigment that transmits incident light in a shorter wavelength region than the first filter. A filter manufacturing method that can be manufactured with high productivity can be provided.

  The invention corresponding to claim 6 is the filter manufacturing method corresponding to claim 5, wherein the first filter is a cyan filter made of a cyan organic pigment, and the second filter is a blue filter made of a blue organic pigment. Therefore, it is possible to manufacture a filter that extracts infrared rays in a wavelength region of about 750 nm to about 800 nm.

  ADVANTAGE OF THE INVENTION According to this invention, the optical sensor, filter, and filter manufacturing method of an infrared region with high productivity can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
(1-1. Configuration)
FIG. 1 is a schematic diagram showing the configuration of the optical sensor 5 according to the first embodiment of the present invention, and FIG. 2 is a diagram showing the configuration of the cross section II ′ of the optical sensor 5 in FIG.

  The optical sensor 5 includes a detection unit 10 and a signal processing unit 20. In the present embodiment, a CMOS is exemplified as the light receiving element.

  The detection unit 10 includes a substrate 11, a light receiving element 12, a planarization layer 13, a filter 14, and a microlens 15.

  The substrate 11 is a semiconductor substrate having a wiring layer that enables transmission and reception of electrical signals. The intensity value of the light received by the light receiving element 12 is sent to the signal processing unit 20 through the wiring layer.

  The light receiving element 12 is formed on the substrate 11 and photoelectrically converts received incident light into an electric signal, and has a function of obtaining an intensity value of the incident light. In addition, the light receiving element 12 sends an intensity value obtained by photoelectric conversion to the calculation unit 21. As will be described later, in this embodiment, a red filter 14R is formed as the filter 14, and a cyan filter 14Cy and a blue filter 14B are stacked on the red filter 14R. Therefore, for the sake of convenience, the light receiving elements that receive the light transmitted through each of the cyan filter 14Cy and the blue filter 14B are referred to as a cyan light receiving element 12Cy and a blue light receiving element 12B, respectively.

  The planarization layer 13 is laminated on the surface on the incident light side of the substrate 11 on which the light receiving element 12 is formed, and the installation surface of the red filter 14R is flattened. The flattening layer 13 is made of an acrylic resin containing 5% of a coumarin dye as a UV absorber in terms of dye concentration.

  The filter 14 is formed by laminating an organic pigment on each of the light receiving elements 12. Here, as the filter 14, a red filter 14R and a cyan filter 14Cy and a blue filter 14B are individually formed on the red filter 14R. The film thickness of each filter is 1.5 μm, and the pixel pitch is 5 μm.

  The red filter 14 </ b> R is a filter that transmits light in a long wavelength region from the red region (that is, light in the red region and light in the infrared region) out of incident light incident on the optical sensor. This red filter 14R includes one or more red pigments selected from CI Pigment Red 179, CI Pigment Red 177, CI Pigment Red 224, and CI Pigment Red 254, and one from CI Pigment Yellow 139 and CI Pigment Yellow 150. Or it forms with the organic pigment which mixed the yellow pigment selected from multiple types. The red filter 14R has a high transmittance for light in a wavelength region of approximately 570 nm or more, and the half-value wavelength is approximately 600 nm.

  The cyan filter 14Cy transmits light in a wavelength region corresponding to cyan. The cyan filter 14Cy is formed from a color resist containing an organic pigment such as C.I. Pigment Blue 15: 3. The cyan filter 14Cy has a transmittance peak value with respect to light having a wavelength of about 480 nm. In addition, the transmittance value gradually decreases for light having a wavelength longer than that, and shows a transmittance value of less than 5% for light having a wavelength of about 580 nm to about 700 nm. And it has a high transmittance value again for light in a wavelength region of about 700 nm or more, and shows a transmittance of 90% or more in a wavelength region of about 780 nm or more. Note that the half-value wavelength is approximately 750 nm.

  The blue filter 14B is for extracting blue light from incident light. The blue filter 14B is formed of a color resist containing an organic pigment such as C.I. Pigment Blue 15: 6 or C.I. Pigment Violet 23. In addition, organic solvents such as cyclohexanone and PGMEA, polymer varnish, monomer, photosensitizer and dispersant are added to the color resist. The blue filter 14B has a peak value of transmittance with respect to light having a wavelength of about 450 nm. For longer wavelengths, the transmittance value gradually decreases and shows a transmittance value of less than 5% for light having a wavelength of about 550 nm to about 750 nm. And it has a high transmittance value again for light in a wavelength region of about 750 nm or more, and shows a transmittance of 90% or more in a wavelength region of about 850 nm or more. Note that the half-value wavelength is approximately 800 nm.

  The spectral characteristics of each of the filters 14R and 14Cy described above and a filter in which 14R and 14Cy are stacked (hereinafter also referred to as a first stacked filter 14RCy) are shown in FIG. In FIG. 3, the horizontal axis and the vertical axis indicate the wavelength and the transmittance, respectively, and the spectral characteristics of the red filter 14R, the cyan filter 14Cy, and the first multilayer filter 14RCy are indicated by lines a1, a2, and a3, respectively. .

  The spectral characteristics of each of the filters 14R and 14B and a filter in which 14R and 14B are laminated (hereinafter also referred to as a second laminated filter 14RB) are shown in FIG. In FIG. 4, the horizontal axis and the vertical axis indicate the wavelength and transmittance, respectively, and the spectral characteristics of the red filter 14R, the blue filter 14B, and the second multilayer filter 14RB are indicated by lines b1, b2, and b3, respectively. .

  Note that the spectral characteristics of each filter can be finely adjusted according to the type and ratio of the pigment, the film thickness of the filter, and the like.

  The microlens 15 is for condensing light on the light receiving element 12 and is formed on the filter 14. Note that the microlens 15 is made of the same material as the planarizing layer 13.

  The signal processing unit 20 includes a calculation unit 21 and an output unit 22.

  The calculation unit 21 performs a subtraction process on the intensity value sent from the cyan light receiving element 12Cy and the intensity value sent from the blue light receiving element 12B. Thereby, the intensity value of the light in the wavelength region corresponding to the difference between the half-value wavelength of the first multilayer filter 12RCy and the half-value wavelength of the second multilayer filter 12RB can be obtained.

  Here, the first multilayer filter 12RCy has a half-value wavelength of about 750 nm, and the second multilayer filter 12RB has a half-value wavelength of about 800 nm. Therefore, the calculation unit 21 can obtain the intensity value of light (infrared rays) in the wavelength region of 750 nm to 800 nm, which is the difference between the two. In addition, the calculation unit 21 sends the light intensity value obtained by the calculation to the output unit 22 as an infrared intensity value.

  The output unit 22 outputs a detection signal when the infrared intensity value calculated by the calculation unit 21 is greater than or equal to a preset value. Here, a detection signal is output to an external device when infrared rays in a wavelength region of approximately 750 nm to approximately 800 nm are detected.

(1-2. Operation)
Next, the operation of the optical sensor 5 according to this embodiment will be described with reference to the flowchart of FIG.

  First, a part of light emitted from the object enters the detection unit 10 as incident light.

  Incident light is collected by the microlens 15, passes through the filter 14, and reaches the light receiving element 12. Here, as the filter 14, a first multilayer filter in which a red filter 14R and a cyan filter 14Cy are stacked and a second multilayer filter in which a red filter 14R and a blue filter 14B are stacked are formed, and the cyan light receiving element 12Cy. In each of the blue light receiving element 12B, light is detected (step S1).

  The light that reaches the cyan light receiving element 12 </ b> Cy and the blue light receiving element 12 </ b> B is converted into an electric signal and sent to the calculation unit 21.

  Thereafter, the calculation unit 21 subtracts the intensity value of the light transmitted through the first multilayer filter and the intensity value of the light transmitted through the second multilayer filter (step S2). That is, the intensity value of light detected by the optical sensor 5 is obtained by the following calculation.

Intensity value of the detection light of the optical sensor 5 = Intensity value of the detection light of the first multilayer filter (Cy + Red) −Intensity value of the detection light of the second multilayer filter (Red + Blue) And the intensity value of the detection light of the optical sensor 5 is set If the value is equal to or greater than the value, the detection signal is output to the external device on the assumption that light in the wavelength region corresponding to the difference between the first multilayer filter and the second multilayer filter has been detected (steps S3-Yes, S4). On the other hand, when the intensity value of the detection light of the optical sensor 5 is less than the set value, the process ends without outputting the detection signal (step S3-No).

(1-3. Effect)
As described above, the optical sensor 5 according to the present embodiment includes the red filter 14R formed on each light receiving element 12 by a red organic pigment, and the cyan color that transmits incident light in a shorter wavelength region than the red filter 14R. The cyan filter (first filter) 14Cy selectively formed on the red filter 14R by the organic pigment and the red filter 14R selectively by the blue organic pigment that transmits incident light in a shorter wavelength region than the cyan filter 14Cy. The blue filter (second filter) 14B, the cyan filter (first filter) 14Cy, and the intensity value obtained from the light receiving element that receives the incident light that has passed through the red filter 14R, the blue filter (second filter) 14B. And an arithmetic means for subtracting the intensity value obtained from the light receiving element that receives the incident light transmitted through the filter 14B and the red filter 14R. With the configuration, since the forming infrared transmission filter using an organic pigment, it can provide a light sensor of high productivity infrared region.

  Further, the optical sensor 5 performs arithmetic processing on the electrical signals of the light transmitted through the cyan filter 14Cy and the red filter 14R made of a cyan organic pigment, and the blue filter 14B and the red filter 14R made of a blue organic pigment. Therefore, the filter having the spectral characteristics as shown in FIG. 6 is apparently provided. In FIG. 6, the horizontal axis and the vertical axis indicate the wavelength and the transmittance, respectively, and spectral lines of the apparent filter obtained by the first multilayer filter, the second multilayer filter, and the arithmetic processing are represented by lines c1, c2, and c3. Each characteristic is shown. That is, the optical sensor 5 according to the present embodiment transmits light in a wavelength region of approximately 720 nm to approximately 850 nm, and is a filter equivalent to a filter having a peak value of approximately 82% transmittance with respect to light having a wavelength of approximately 780 nm. It is equipped with. For this reason, the optical sensor 5 can detect infrared rays in a wavelength region of about 750 nm to about 800 nm.

  Moreover, since the microlens 15 for condensing light on the light receiving element 12 is formed on the filter 14, the filter 14 can be thinned, and the small photosensor 5 can be provided. For example, the aperture ratio of a light receiving element such as a CMOS or CCD is usually as low as 20 to 40%. On the other hand, according to the detection unit 10 according to the present embodiment, the distance between the microlens 15 and the light receiving element 12 can be shortened. Therefore, the incident angle of incident light can be increased, and the sensitivity of the optical sensor 5 can be increased.

  The microlens 15 may be a phenolic, polystyrene, or acrylic resin, but is preferably polystyrene or, preferably, acrylic, from the viewpoint of heat resistance. A transparent resin having a low refractive index, such as a fluorine-containing acrylic resin, is also preferable. In the configuration in which an antireflection film or a low refractive index resin film is laminated on the microlens 15, the material of the microlens 15 may be a microlens made of silicon nitride, silicon oxynitride, or the like.

  Further, the planarization layer 13 according to the present embodiment is formed of an acrylic resin containing 5% of a coumarin-based dye as a UV absorber in a dye concentration. Therefore, the spectral characteristics of the planarization layer 13 have a point that the transmittance is 50% for light with a wavelength of 365 nm to 420 nm, and the transmittance is 90% or more for light with a wavelength of 450 nm or more. Can be. In this case, the planarization layer 13 can absorb the influence of halation from the substrate 11 when the filter 14 is pattern-exposed by photolithography, and the pixel thickness of the filter 14 can be suppressed.

(Modification)
In the photosensor 5 of the present embodiment, the cyan filter 14Cy or the blue filter 14B is formed on the red filter 14R. However, as shown in FIG. 7, the red filter is placed on the cyan filter 14Cy or the blue filter 14B. Even if 14R is formed, the same effect can be obtained.

  In the photosensor 5 of the present embodiment, the cyan filter 14Cy or the blue filter 14B is formed on the red filter 14R. However, the first multilayer filter is formed by mixing a red organic pigment and a cyan organic pigment. Alternatively, the second multilayer filter may be formed by mixing a red organic pigment and a blue organic pigment. However, when organic pigments are mixed, visible light is not transmitted, and alignment during pattern exposure becomes difficult, which may reduce productivity. Therefore, from the viewpoint of alignment, a layer in which organic pigment filters are laminated is more preferable than a filter in which organic pigments are mixed.

<Second Embodiment>
In the second embodiment of the present invention, a method for manufacturing the filter of the detection unit 10 according to the first embodiment will be described with reference to the process diagrams of FIGS.

  First, the planarization layer 13 is formed on the substrate 11 on which the light receiving element 12 (12Cy · 12B in FIG. 8) is formed. Here, an acrylic resin coating solution containing 5% of a coumarin dye at a dye concentration is spin-coated at a rotation speed of 2000 rpm, and then hardened by a heat treatment at 180 ° C. or more, whereby a film thickness of 0.1 μm is obtained. A planarization layer 13 is formed (FIG. 8A).

  Next, a red resin layer RL having a thickness of about 1.5 μm is formed on the planarizing layer 13. The red resin layer RL is a photosensitive resin layer to which organic pigments such as C.I. Pigment Red 177 and C.I. Pigment Yellow 139 are added. And this red resin layer RL is pattern-exposed. Here, the exposed portion undergoes a photochemical reaction and becomes insoluble in alkali. Thereafter, a portion not irradiated with light is removed using a developing solution such as an alkaline solution to form a red filter 14R (FIG. 8B).

  Subsequently, a blue resin layer BL having a thickness of about 1.5 μm is formed on the red filter 14R. The blue resin layer BL is a photosensitive resin layer to which an organic pigment such as C.I. Pigment Blue 15: 6 or C.I. Pigment Violet 23 is added. Then, the blue resin layer BL is subjected to pattern exposure using the mask M (FIG. 8C). Here, the exposed portion undergoes a photochemical reaction and becomes insoluble in alkali. Thereafter, a portion not irradiated with light is removed using a developing solution such as an alkaline solution to form a blue filter 14B (FIG. 8D).

  Further, by the same photolithography process, a cyan filter 14Cy having a thickness of about 1.5 μm is formed using an organic pigment such as C.I. Pigment Blue 15: 3 (FIG. 9A).

  Thus, after forming the red filter 14R, the blue filter 14B, and the cyan filter 14Cy, a transparent resin layer WL having a thickness of about 2 μm is formed. The transparent resin layer WL is the same material as the planarizing layer 13.

  Further, the phenol resin layer 16 is formed on the transparent resin layer WL (FIG. 9B). The phenol resin layer 16 is formed in order to obtain a microlens 15 having a desired shape by controlling an etching rate during dry etching described later. The phenol resin layer 16 plays a role of controlling the heat flow when the lens matrix 17M is formed by heat flow.

  Subsequently, a photosensitive resin layer 17 is formed on the phenol resin layer 16. The photosensitive resin layer 17 can be formed of, for example, an alkali resin having alkali solubility, photosensitivity, and heat flow.

  Next, the photosensitive resin layer 17 is formed into a rectangular pattern by a photolithography process. Then, the rectangular pattern is cured while being melted by heat treatment, and then cooled. As a result, the lens matrix 17M having a hemispherical shape can be formed by the surface tension of the resin at the time of melting (FIG. 9C).

  Subsequently, dry etching is performed using the lens matrix 17M as a mask. Thereby, the shape of the lens matrix 17M is transferred to the photosensitive resin layer 17 via the phenol resin layer 16, and the microlens 15 is formed (FIG. 9D).

  In order to increase the aperture ratio of the microlens, improve the shape of the microlens, and prevent the lens surface from being roughened, the etching rate of the lens matrix 17M is set higher than the etching rate of the phenol resin 16, and the transparent resin layer It is desirable that the etching rate of WL be higher than or equal to the etching rate of the phenol resin layer 16.

  The filter of the detection unit 10 can be manufactured by the method described above.

  That is, according to the filter manufacturing method according to the present embodiment, the light receiving element 12Cy is obtained from the cyan light receiving element 12Cy (first light receiving element) and the blue light receiving element 12B (second light receiving element) formed on the substrate 11, and the cyan light receiving element 12Cy. A filter used in the optical sensor 5 provided with a calculation unit 21 that subtracts the intensity value obtained from the intensity value obtained from the blue light-receiving element 12B, and is a red filter that is sequentially stacked on the cyan light-receiving element 12Cy. A filter including the 12R and the cyan filter 12Cy, and the red filter 12R and the blue filter 12B sequentially stacked on the blue light receiving element 12B can be manufactured.

  In the filter manufacturing method according to the present embodiment, red, cyan, and blue organic pigments are used. Therefore, a filter that detects infrared rays in a wavelength region of about 750 nm to about 800 nm can be manufactured.

  Moreover, in the filter manufacturing method according to the present embodiment, since the filter is manufactured using an organic pigment, it is not necessary to use a vacuum evaporation apparatus. Therefore, productivity can be improved compared with manufacture of an inorganic filter. Specifically, since the infrared transmission filter is formed by photolithography, it can be manufactured at a lower cost than vacuum deposition.

  Furthermore, in the filter manufacturing method according to the present embodiment, since the filter is manufactured using an organic pigment, rework is possible even when a spectral abnormality occurs, and an expensive device is not wasted. In addition, there are fewer defects and less spectral shift due to the incident angle of light than inorganic filters.

(Comparative example)
A comparative example of the filter (organic pigment filter) of the detection unit 10 and the inorganic filter 50 according to the present embodiment is shown.

FIG. 10 is a diagram showing a cross-sectional configuration of the inorganic filter 50. Here, inorganic filter 50, as a first layer of TiO ₂ on a silicon wafer by vacuum evaporation, to form overlapping 70 layers alternately and SiO ₂ and TiO ₂ thereon. The total film thickness was 4.0 μm. The TiO ₂ film was formed at a gas pressure of 1.5 × 10 ⁻² and a temperature of 340 ° C., and the SiO ₂ film was formed at a gas pressure of 1.4 × 10 ⁻³ and a temperature of 340 ° C.

  When the inorganic filter 50 was formed by the above-described procedure, light having a wavelength range of approximately 760 nm to approximately 810 nm was transmitted, and a peak having a transmittance of approximately 90% with respect to light having a wavelength of approximately 780 nm was obtained.

  The spectral characteristics of the inorganic filter 50 and the organic pigment filter according to the present embodiment are shown as lines d1 and d2, respectively, in FIG. As a result, it can be seen that the organic pigment filter according to the present embodiment can obtain the same spectral sensitivity as that of the inorganic filter.

  Further, the incident angle dependency of the spectral characteristics of the inorganic filter 50 is shown in FIG. In FIG. 12, lines e1, e2, and e3 indicate the incident light angles of 0 degrees, 15 degrees, and 25 degrees, respectively. Thus, in the inorganic filter 50, the spectrum shifts depending on the incident angle. For this reason, depending on the angle of incident light, light may not be detected. In contrast, the organic pigment filter has a small spectral shift due to the angle of the incident light, and thus can detect light without depending on the angle of the incident light.

  The spectroscopic measurement was performed as follows.

  First, the film thickness of each filter 14 on the light receiving element 12 and the film thickness of the transparent resin (flattening layer 13 and transparent resin layer WL) are measured. In addition, about transparent resin, a film | membrane is formed on Si substrate and the film thickness is measured with a contact-type film thickness meter (DektakIIA by Sloan).

  Then, a transparent resin and a filter 14 having the same thickness as the measured thickness are formed on a glass substrate, and the spectrum is measured with a spectrophotometer (U-3400 spectrophotometer manufactured by Hitachi, Ltd.). At this time, the spectral characteristic when there is a filter or a transparent resin is measured using the value of only the glass substrate (no filter or transparent resin) as a reference. The transmittance value is 100% for transparent glass having a refractive index of 1.5.

<Others>
Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine a component suitably in different embodiment.

It is a schematic diagram which shows the structure of the optical sensor 5 which concerns on the 1st Embodiment of this invention. It is a figure which shows the structure of the I-I 'cross section of the optical sensor 5 which concerns on the embodiment. It is a figure which shows the spectral characteristics of the 1st multilayer filter which concerns on the same embodiment. It is a figure which shows the spectral characteristics of the 2nd multilayer filter which concerns on the same embodiment. It is a flowchart for demonstrating operation | movement of the optical sensor 5 which concerns on the same embodiment. It is a figure which shows the spectral characteristic of the filter which the optical sensor 5 which concerns on the embodiment apparently comprises. It is a figure showing a modification of a filter concerning the embodiment. It is process drawing for demonstrating the manufacturing method of the detection part 10 which concerns on the 2nd Embodiment of this invention. It is process drawing for demonstrating the manufacturing method of the detection part 10 which concerns on the same embodiment. It is a figure which shows the structure of the cross section of the inorganic filter 50 which concerns on the comparative example of the embodiment. It is a figure which shows the spectral characteristics of the filter 14 and the inorganic filter 50 of the embodiment. It is a figure which shows the incident angle dependence of the inorganic filter 50 which concerns on the comparative example of the embodiment.

Explanation of symbols

5 ... Optical sensor, 10 ... Detection unit, 11 ... Substrate, 12 ... Light receiving element,
12Cy ... Cyan light receiving element, 12B ... Blue light receiving element, 13 ... Flattening layer,
14 ... Filter, 14R ... Red filter, 14Cy ... Cyan filter,
14B ... Blue filter, 15 ... Microlens, 20 ... Signal processing unit,
21 ... Calculation unit, 22 ... Output unit, 50 ... Inorganic filter.

Claims (6)

A substrate,
A plurality of light receiving elements formed on the substrate for obtaining an intensity value of received incident light;
On each of the light receiving elements, a red filter formed of a red organic pigment,
A first filter selectively formed on the red filter by a first organic pigment that transmits incident light in a shorter wavelength region than the red filter;
A second filter selectively formed by a second organic pigment that transmits incident light in a shorter wavelength region than the first filter at a position on the red filter different from the position at which the first filter is formed; ,
Obtained from a light-receiving element that receives incident light that has passed through the second filter and the red filter, based on an intensity value obtained from the light-receiving element that has received incident light that has passed through the first filter and the red filter. An optical sensor comprising an arithmetic means for subtracting the intensity value. The optical sensor according to claim 1,
The first filter is a cyan filter made of a cyan organic pigment,
The optical sensor, wherein the second filter is a blue filter made of a blue organic pigment. A substrate,
A plurality of light receiving elements formed on the substrate for obtaining an intensity value of received incident light;
A red filter selectively formed with a red organic pigment on the light receiving element;
A cyan filter selectively formed by a cyan organic pigment that transmits incident light in a shorter wavelength region than the red filter at a position on the light receiving element different from the position at which the red filter is formed;
A blue filter selectively formed with a blue organic pigment that transmits incident light in a shorter wavelength region than the cyan filter at a position on the light receiving element different from the position where the red filter and the cyan filter are formed; ,
And a calculation means for obtaining an intensity value of light in the infrared region based on an intensity value obtained from a light receiving element that receives incident light transmitted through each of the red filter, the cyan filter, and the blue filter. Features an optical sensor. A first light receiving element and a second light receiving element formed on the substrate;
A filter used in an optical sensor comprising an arithmetic means for subtracting an intensity value obtained from the first light receiving element and an intensity value obtained from the second light receiving element,
A red filter composed of a red organic pigment and a cyan filter composed of a cyan organic pigment, which are sequentially laminated on the first light receiving element;
A filter comprising: a red filter made of a red organic pigment and a blue filter made of a blue organic pigment, which are sequentially laminated on the second light receiving element. A red filter forming step of forming a red filter made of a red organic pigment on the plurality of light receiving elements formed on the substrate;
A first filter forming step of selectively forming on the red filter a first filter made of a first organic pigment that transmits incident light in a shorter wavelength region than the red filter;
A second filter made of a second organic pigment that selectively transmits incident light in a shorter wavelength region than the first filter is selectively formed at a position on the red filter that is different from the position where the first filter is formed. A filter manufacturing method comprising two filter forming steps. In the filter manufacturing method of Claim 5,
The first filter is a cyan filter made of a cyan organic pigment,
The filter manufacturing method, wherein the second filter is a blue filter made of a blue organic pigment.

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