JP2009278527A - Imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device which can reduce image degradation caused by the scatter or fall of a filler. <P>SOLUTION: The imaging device 1 includes a semiconductor image pickup device 5 which converts incident light to an electric signal, an optical filter 4 which is opposed to the incident surface of the semiconductor image pickup device 5 and allows the passage of light, and a three-dimensional substrate 2 which holds the optical filter 4 by being bonded by an adhesive 6 containing a filler. The particle size of the filler is set based on the transmission wavelength of the optical filter, for example, the particle size is substantially one tenth or smaller than the transmission wavelength of the optical filter. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging device using a semiconductor imaging device.

  2. Description of the Related Art Conventionally, there has been known an imaging apparatus configured to use a semiconductor imaging device such as a CCD (Charge Coupled Device) to convert light incident through a lens into an electrical signal and take a captured image. Such an imaging device is widely used in portable devices such as a mobile phone and a portable information terminal.

  With the demand for miniaturization and high performance of portable equipment equipped with an imaging device, there has been a further demand for miniaturization and weight reduction of the imaging device. In response to this requirement, the imaging device has been made thinner by thinly configuring the components of the imaging device. In addition, as the number of pixels is increased in response to a demand for high image quality, the pixel size has also been reduced.

  Here, black spots, white spots, or the like may occur in the captured image due to defects in the image sensor or dust attached to the image sensor. These black spots and white spots are commonly called “scratches”. Conventionally, in assembling an image pickup apparatus, improvement of the cleanliness of the working environment, strengthening of cleaning of components, static electricity removal by an ionizer, and the like have been performed in order to prevent scratches from being generated due to dust adhering to the image pickup element. In addition, when the output from a certain pixel is reduced due to dust or the like, a defect correction is performed that estimates the output of the pixel based on information obtained from surrounding pixels and corrects the pixel as if it is operating normally. Was done.

  In order to make light of a predetermined wavelength incident on the semiconductor image sensor, an optical filter may be provided close to the semiconductor image sensor. The adhesive that fixes this optical filter generally contains a filler, but the filler may scatter when the optical filter is bonded, or the filler may fall off after the adhesive is cured. There is a problem that the image quality deteriorates due to adhesion to the incident surface of the image sensor.

For such a problem, Patent Document 1 discloses an imaging device in which the diameter of the filler contained in the adhesive is set to be equal to or smaller than the pixel size. In the imaging device described in Patent Document 1, by setting the diameter of the filler made of silicon dioxide (SiO ₂ ) to be equal to or smaller than the pixel size, even if the filler adheres to the semiconductor imaging element due to scattering or dropping, the filler Since the output information of the neighboring pixels adjacent to the attached pixel can be acquired, the image can be corrected based on this output information.
JP 2004-327914 A

  However, in the imaging device described in Patent Document 1, when the filler adheres to the incident surface of the semiconductor imaging element, defective pixels are interpolated based on output information of peripheral pixels adjacent to the pixel to which the filler adheres. Compared with the case where there is no color, the output signal quality is inevitably lowered, and the color reproducibility is inevitably deteriorated.

  In addition, Mie scattering may occur depending on the size of the filler and the wavelength of light to be used, which may cause deterioration in color reproducibility. Note that Mie scattering is likely to occur when the particle size approximates the wavelength of light.

In addition, in the imaging device described in Patent Document 1, since silicon dioxide, which is a relatively highly transmissive substance, is used as a filler material, the surface resistivity is 10 ¹⁵ (Ω / □) or more, and the surface of the filler is reduced. Easily charged with static electricity. For this reason, the scattered or detached filler tends to adhere to the incident surface of the image sensor due to electrostatic charging, and the filler adhered to the incident surface of the image sensor in the assembly process or inspection process of the image sensor and the three-dimensional substrate or the optical filter. There was a case where it was not possible to remove it by air blow. Furthermore, depending on the particle size of silicon dioxide, the dispersibility of the filler in the adhesive is deteriorated and the particles are aggregated. For this reason, even if a filler having a diameter smaller than the pixel size is used, the aggregated aggregate of fillers becomes larger than the pixel size, and the above-described defective pixel cannot be interpolated.

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide an imaging apparatus that can reduce image quality deterioration due to scattering or dropping of fillers.

  An image pickup apparatus according to the present invention includes a semiconductor image pickup device that converts incident light into an electric signal, an optical filter that is disposed to face an incident surface of the semiconductor image pickup device, and an adhesive that includes an adhesive. A holding member that holds the optical filter, and the particle diameter of the filler is set based on a transmission wavelength of the optical filter.

  Light scattering is generally related to the size of the particles and the wavelength of the light hitting the particles. With the configuration of the present invention, light scattering by the filler can be suppressed by adjusting the relationship between the particle diameter of the filler and the transmission wavelength of the optical filter. Thereby, even if a filler adheres to a semiconductor image sensor, image quality deterioration due to scattering or dropping of the filler can be reduced.

  In the imaging device according to the present invention, the filler has a configuration in which a particle diameter of the filler is substantially 1/10 or less of a shortest wavelength of a transmission wavelength of the optical filter.

  With this configuration, the particle size of the filler is substantially 1/10 or less of the shortest wavelength of the transmission wavelength of the optical filter. Therefore, the filler contained in the adhesive that bonds the optical filter may be scattered or adhered during bonding. Even if it drops off after curing the agent and adheres to the semiconductor imaging device, the light impinging on the filler is scattered according to the Rayleigh scattering law, so the intensity of the scattered light caused by the filler is reduced. It can be made very small, the filler can be made optically transparent, and as a result, the occurrence of black scratches can be suppressed. As a result, even if the filler adheres to the semiconductor image sensor, the output of the pixel to which the filler is attached can be obtained without correction using the output of the surrounding pixels, and the image quality deterioration due to the scattering or dropping of the filler is reduced. be able to. Mie scattering occurs when the particle size approximates the wavelength of light, whereas Rayleigh scattering occurs when the particle size is smaller than the light wavelength. Therefore, by making the particle size of the filler substantially equal to or less than 1/10 of the shortest wavelength of the transmission wavelength of the optical filter, it is possible to reliably scatter the light colliding with the filler with respect to the light in the transmission wavelength range of the optical filter. It can be an area of Rayleigh scattering. Thereby, since Mie scattering can be suppressed, deterioration of color reproducibility can be prevented.

  In the imaging device according to the present invention, the holding member is a three-dimensional substrate. With this configuration, each component of the imaging device can be attached to the three-dimensional substrate, so that the workability during assembly is improved. In addition, since the constituent elements can be assembled and attached on the basis of the three-dimensional substrate, the imaging apparatus can be assembled with high accuracy.

  In the imaging device according to the present invention, the filler has a spherical shape. With this configuration, the anisotropy of the adhesive with respect to the temperature expansion can be eliminated, and the anisotropy of the holding member to be bonded can be reduced. Thereby, the strength of the holding member can be improved and the imaging apparatus can be thinned.

  Moreover, the imaging device which concerns on this invention WHEREIN: The said filler has the structure which has electroconductivity.

  In the present invention, since the particle size of the filler is set based on the size of the transmission wavelength of the filter, as described above, the intensity of the scattered light by the filler can be very small, and the filler can be optically transparent. it can. Thereby, for example, conductive particles such as metal particles and carbon can be used for the filler without being limited to a material having relatively high permeability such as silicon dioxide. Therefore, it can prevent adhering to a semiconductor image pick-up element. Further, by using conductive particles as the filler contained in the adhesive, the charging of the filler can be reduced. As a result, the filler becomes difficult to adhere to the optical filter, so that it is not necessary to perform an antistatic treatment on the optical filter. Furthermore, by reducing the charging of the filler in the assembly process or inspection process of the semiconductor image sensor and the three-dimensional substrate or the optical filter, it is also possible to prevent the charge on the incident surface of the semiconductor image sensor. It can prevent adhering to the entrance surface of the semiconductor image sensor due to static electricity. In addition, since charging does not easily occur on the incident surface of the semiconductor image sensor, even if filler or dust adheres to the incident surface of the image sensor, the adhered filler or dust can be easily removed by air blow or the like.

  In the imaging device according to the present invention, a single-layer or multi-layer dielectric film is formed on the incident surface of the optical filter. Thereby, the loss of light at the incident surface of the optical filter can be prevented and the transmittance can be improved.

  The present invention has an effect of suppressing the scattering of light by the filler by setting the particle diameter of the filler based on the transmission wavelength of the optical filter, and reducing the image quality deterioration due to the scattering or dropping of the filler. An apparatus can be provided.

  Hereinafter, imaging devices according to embodiments of the present invention will be described with reference to the drawings. When possible, the same portions are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a cross-sectional view of an imaging apparatus according to an embodiment of the present invention, and FIG. 2 is a perspective view thereof. As shown in FIG. 1 and FIG. 2, the imaging device 1 includes an aspheric lens 3 disposed along the optical axis L, an optical filter 4 and a semiconductor imaging device 5, and a three-dimensional substrate 2 that holds these, A flexible printed circuit board (FPC) 10 connected to the three-dimensional board 2 is provided.

  In the present embodiment, the three-dimensional substrate 2 has a role of fixing the semiconductor imaging device 5 and also serves as a holding member for holding the optical filter 4. The three-dimensional substrate 2 includes a cylindrical barrel portion 2a and a bottom portion 2b continuous with one end surface of the barrel portion 2a. In the following description, the lens barrel 2a side is the upward direction, and the bottom 2b side is the downward direction.

  First, the three-dimensional substrate 2 will be described. The lens barrel 2a is located on the upper surface of the bottom 2b and extends in the vertical direction. The bottom 2b has a recess formed in the center of its lower surface. In addition, an opening A centering on the optical axis L is formed in the bottom portion 2b, and light can pass through the opening A and a hollow portion of the lens barrel portion 2a. A portion 8 surrounding the opening A of the three-dimensional substrate 2 is made of glass reinforced PPA (polyphthalamide resin) or the like, and is black to prevent light transmission. A necessary wiring pattern 9b is formed on the lower surface of the lower surface 2b of the bottom 2b by electroless plating or the like. This wiring pattern 9b is provided on the outer side of the bottom 2b of the three-dimensional board 2 for connection to the connection land 9c provided on the bottom surface of the bottom 2b of the three-dimensional board 2 so that the semiconductor imaging device 5 can be barely mounted. It has a provided terminal 9a (see FIG. 2). As described above, by using the three-dimensional substrate 2 as a holding member that holds the optical filter 4, each component of the imaging device 1 can be attached to the three-dimensional substrate 2, so that workability during assembly is improved. In addition, since the components can be assembled and attached based on the three-dimensional board 2, the imaging device 1 can be assembled with high accuracy.

  The aspherical lens (hereinafter referred to as “lens”) 3 is made of a resin that can satisfy necessary optical characteristics such as transmittance and refractive index, and is fitted into the inner periphery of the lens barrel portion 2 a of the three-dimensional substrate 2. Yes. In the present embodiment, ZEONEX (registered trademark) manufactured by Nippon Zeon Co., Ltd. is used for the lens 3. Although only one lens is shown in FIG. 1 for the sake of simplicity, the lens 3 is actually composed of a plurality of lenses, and has a so-called pan focus configuration in which an object farther than a certain distance can be imaged. . Here, the lens 3 is focused on a subject farther than about 30 cm. The configuration and characteristics of the lens 3 are not limited to those of the present embodiment, and can be selected as appropriate. Above the lens 3, the lens 3 is fixed, and a diaphragm 7 serving as a required opening is attached.

The optical filter 4 is provided with an IR (InfraRed) cut coat on one side of a base material made of borosilicate glass and an antireflection AR (Anti Reflection) coat on the other side. For example, silicon dioxide (SiO ₂ ), titanium oxide (TiO ₂ ) or the like is used for the IR cut coat, and is deposited as a dielectric film on the substrate. For the AR coating for preventing reflection, for example, aluminum oxide (Al ₂ O ₃ ), magnesium fluoride (MgF ₂ ), zirconium oxide (ZrO ₂ ) or the like is used, and is deposited on the substrate as a dielectric film. . The AR coating is applied on the incident surface of the optical filter 4, and the IR cut coating is applied on the surface opposite to the incident surface of the optical filter 4. By forming a single-layer or multi-layer dielectric film on at least the incident surface of the optical filter 4 as the AR coating, light loss on the surface of the optical filter can be prevented and the transmittance can be improved. Further, by forming a single-layer or multi-layer dielectric film on the surface opposite to the incident surface of the optical filter 4 as an IR cut coat in addition to the AR coat, the transmittance can be improved more effectively. it can. By using borosilicate glass for the base material, the optical filter 4 can suppress ultraviolet light transmission. With such a configuration, the optical filter 4 has a function of suppressing transmission of light outside the visible light region.

  FIG. 3 is a diagram showing the spectral characteristics of the optical filter 4 used in the imaging apparatus 1. As can be seen from FIG. 3, in the optical filter 4, the transmittance is about 93% or more from about 400 nm to about 800 nm, and the transmittance is sufficiently low in other bands. The spectral characteristics of the optical filter 4 are not limited to those in the present embodiment, and can be changed as appropriate. The optical filter 4 is disposed on the upper side of the opening A along the optical axis L, and is fixed to the three-dimensional substrate 2 by a UV curing type or UV / heat combination type adhesive 6 made of epoxy resin. The optical filter 4 has an AR-coated surface (incident surface) facing the lens 3.

  The semiconductor image pickup device 5 is a 1/4 inch UXGA (Ultra etended Graphics Array) type CCD having about 2 million pixels, and has a pixel size of about 2.2 μm. The semiconductor imaging device 5 is so-called face-down mounted on a connection land 9c provided on the three-dimensional board 2 by a connection method such as SBB (Stud Bump Bond), and is electrically connected to the wiring pattern 9b. The semiconductor imaging element 5 uses a dye-based color filter not shown in FIGS. 1 and 2 so that RGB signal outputs can be obtained, and a light receiving portion is formed corresponding to each.

  FIG. 4 is a schematic diagram illustrating an example of the color arrangement of pixels in the semiconductor image sensor 5. In FIG. 4, for example, a portion indicated by “R” in the imaging surface of the semiconductor imaging device 5 receives light having a red wavelength that has passed through the color filter, and thereby a portion indicated by “R” is red. Can be detected. Similarly, a portion indicated by “B” receives light of blue wavelength transmitted through the color filter, and a portion indicated by “G” receives light of green wavelength transmitted through the color filter. The semiconductor imaging device 5 is disposed so that the imaging surface (incident surface) faces the optical filter 4 and covers the opening A in the vicinity of the center of the bottom surface of the bottom 2b. As described above, since the recess is formed in the center of the bottom 2b, the semiconductor image pickup device 5 attached to the lower surface is separated from the FPC 10. In addition, chip parts (not shown) are also arranged on the bottom surface of the bottom 2b.

  From the above description, in the optical system of the imaging device 1 in the present embodiment, the light from the subject is collected by the lens 3 and enters the semiconductor imaging device 5 through the optical filter 4 that transmits the light in the visible light region. It can be seen that it is configured to.

  The FPC 10 provided below the three-dimensional board 2 is electrically connected to the terminals 9 a of the three-dimensional board 2 by the solder 12 and mechanically fixed on the land 13 on the FPC 10. The FPC 10 includes a polyimide base film 10a having a thickness of 1/2 Mil (12.5 μm) and a rolled copper 10b having a thickness of 1/3 Oz (12 μm). The FPC 10 is provided with a signal processing DSP (Digital Signal Processor) not shown. The DSP has functions of converting electrical signals output from the semiconductor image sensor 5 into signals of a required format and processing such as white balance and color correction, and is connected to devices such as mobile phones and mobile terminals. ing.

  The DSP has a function called “scratch correction”. “Scratch correction” refers to non-output pixels caused by CCD defects and dust, and estimates the output from defective pixels based on information obtained from pixels arranged around the pixels. Thus, the correction is performed as if the pixel is operating normally. As a defect correction method, a method using an average value of outputs from adjacent pixels, a method of interpolating from output values from adjacent pixels, or the like can be used. Further, the identification of the scratch is determined by whether the output value from the target pixel in a certain finite range exceeds a certain threshold value or falls below another threshold value.

  The imaging apparatus 1 operates as follows. Light from the subject passes through the aperture 7 and is collected by the lens 3. Subsequently, the light collected by the lens 3 enters the optical filter 4, and infrared light and ultraviolet light are cut by the optical filter 4. Visible light that has passed through the optical filter 4 enters the semiconductor imaging device 5 and is converted into a required electrical signal, and the converted electrical signal is output from the semiconductor imaging device 5. Then, the electrical signal output from the semiconductor image sensor 5 is led to the terminal portion 9a provided on the bottom portion 2b via the wiring pattern 9b, and a captured image is displayed on a display (not shown). The display is configured to output at a frame rate of 30 frames / second, for example, with a screen aspect ratio of 4: 3.

  Next, the assembly sequence of the imaging device 1 according to the embodiment of the present invention will be described. First, after the optical filter 4 is set on the three-dimensional substrate 2, a required amount of UV curing type or UV / heat type epoxy adhesive 6 is applied around the optical filter 4 by a dispenser or the like. Next, the adhesive 6 is cured and cured by an ultraviolet irradiation device (not shown). It is desirable to optimize the wavelength of the ultraviolet rays to be irradiated, the irradiation time, and the like according to the curing state of the adhesive 6. In the case of using an adhesive formulated so that heat curing can be performed for UV curing, the curing initiator is activated by irradiating ultraviolet rays, and then heated to complete the curing.

  Next, the semiconductor imaging element 5 is bonded to the lower surface of the bottom 2b of the three-dimensional substrate 2. At this time, the semiconductor image sensor 5 is arranged so that the imaging surface corresponds to the opening A. Subsequently, the lens 3 is mounted on the three-dimensional substrate 2 above the optical filter 4, and a diaphragm 7 that holds the lens 3 from above is attached to fix the lens 3. Finally, the three-dimensional substrate 2 to which the optical filter 4 and the semiconductor image sensor 5 are attached is placed on the FPC 10 and both are fixed by the solder 12 to complete the image pickup apparatus 1.

Here, the adhesive 6 for bonding the optical filter 4 to the three-dimensional substrate 2 will be described. As described above, glass reinforced PPA (polyphthalamide resin) is used for the three-dimensional substrate 2, and the linear expansion coefficient thereof is about 40 × 10 ⁻⁶ mm / ° C. On the other hand, the linear expansion coefficient of the optical filter 4 is about 10 × 10 ⁻⁶ mm / ° C. In order to fix both of these appropriately, the adhesive 6 has a filler (not shown) so that the linear expansion coefficient of the adhesive 6 is a value between the linear expansion coefficient of the three-dimensional substrate 2 and the linear expansion coefficient of the optical filter 4. It is included.

As the filler material, in addition to silica, which is a fine particle made of silicon dioxide (SiO ₂ ) suitable for optical use, a metal or carbon excellent in conductivity can be used. In addition, it is preferable to use a spherical filler so that the adhesive 6 does not have anisotropy after being cured. That is, by making the shape of the filler spherical, the anisotropy of the adhesive with respect to the temperature expansion can be eliminated, and the anisotropy of the holding member to be bonded can be reduced. Thereby, the strength of the three-dimensional board 2 as the holding member can be improved, and the imaging apparatus 1 can be thinned.

  The particle diameter of the filler is substantially 1/10 or less of the shortest wavelength of the light transmitted through the optical filter 4. Hereinafter, the reason why the particle diameter of the filler contained in the adhesive is within this range will be described.

  Prior to specific description of the particle size of the filler, problems caused by the adhesive containing the filler will be described. When the adhesive is cured, the filler contained in the adhesive may be scattered, or part of the filler may be exposed particularly at the end face portion. Further, after the optical filter 4 is attached to the three-dimensional substrate 2, the semiconductor image pickup device 5 and the optical system lens 3 are attached, or the FPC 10 is mounted, and if necessary, a focus adjustment process is performed. The filler at the end face part may fall off due to impact or the like. And it became clear by the analysis of the imaging device that the scattered or dropped filler adheres to the surface of the semiconductor imaging device 5 and causes the output from the pixel to decrease. In recent years, in particular, with the downsizing of imaging devices, it has become difficult to ensure the dimensions of parts necessary for device disassembly, and many devices cannot be disassembled. In such an imaging apparatus, when the scattered or dropped filler adheres to the surface of the semiconductor imaging element 5, there has been a situation in which the imaging apparatus has to be discarded.

Next, it will be described that when the particle diameter of the filler is 1/10 or less of the wavelength of light, the filler becomes optically transparent. It is known that light scattering is very much related to the size of particles (filler) and the wavelength of light hitting the particles. When the particle diameter is sufficiently smaller than the wavelength of light, the theoretical formula is as follows according to Rayleigh scattering.

FIG. 5 is a diagram showing the principle of Rayleigh scattering, and shows the intensity pattern of scattered light when incident light is applied to particles. In FIG. 5, I ₁ is the scattering intensity in the vertical direction, and I ₂ is the scattering intensity in the horizontal direction. As shown in FIG. 5, in Rayleigh scattering, light is scattered symmetrically in the horizontal direction of incident light, and the scattering distribution has directivity. The scattering directivity at this time can be regarded as the directivity of a minute dipole regardless of the material and shape.

FIG. 6 is a diagram showing the relationship between the intensity of scattered light and the particle diameter. FIG. 6 is a Rayleigh scattering formula represented by the above formula (1).
Wavelength of light λ = 400, 550, 800 (nm),
Distance R = 10 (nm) from the scattering particles,
Absolute refractive index m of particles = 1.45,
Outgoing light angle with respect to incident light θ = 0 °
Is a graph plotting the particle diameter d on the horizontal axis and the intensity of scattered light on the vertical axis.

  As apparent from FIG. 6, in the region where the particle diameter d is 1/10 of the wavelength of the light, the intensity of the scattered light in any case where the light wavelength is λ = 400, 550, 800 (nm). Is very small and can be as close to 0 as possible (the intensity of scattered light is about 0.01 or less at any of the particle diameters d = 40 nm, 55 nm, and 80 nm). Therefore, it can be seen that if the particle diameter d is 1/10 or less of the wavelength of light, the intensity of the scattered light can be made very small and the particles can be made optically transparent. Further, it is understood that when the intensity of the scattered light is to be suppressed to 0.01 or less, for example, the particle diameter must be reduced as the wavelength is shorter. For this reason, when the transmission wavelength range of the optical filter 4 is 400 nm to 800 nm, if the particle diameter is 1/10 or less of the shortest wavelength 400 nm of the transmission wavelength range of the optical filter 4, the transmission wavelength range of the optical filter 4 The particles can be made optically transparent in the entire range.

  That is, by setting the particle diameter of the filler contained in the adhesive 6 to at least 1/10 or less of the shortest wavelength of the transmission wavelength of the optical filter 4, the filler in the adhesive 6 is placed on the incident surface of the semiconductor imaging device 5. Even if the scattered or dropped filler adheres to the incident surface of the semiconductor imaging device 5, the light that collides with the filler is scattered according to the Rayleigh scattering law, so that the scattered light caused by the filler is scattered. The strength can be made very small and the filler can be made optically transparent. As a result, the output of the semiconductor imaging device 5 does not decrease, and the occurrence of black flaws can be suppressed. As a result, it is possible to reduce image quality deterioration due to the scattering or dropping of the filler. In addition, a function (scratch correction function) for correcting a black scratch that has been conventionally provided in an imaging apparatus is not required. Accordingly, the number of DSP processing circuits can be reduced, which leads to cost reduction of parts.

  Mie scattering occurs when the particle size approximates the wavelength of light, whereas Rayleigh scattering occurs when the particle size is smaller than the light wavelength. Therefore, by setting the particle size of the filler to 1/10 or less of the shortest wavelength of the transmission wavelength of the optical filter, the scattering of the light that collides with the filler with respect to the light in the transmission wavelength range of the optical filter is regarded as the Rayleigh scattering region. can do. Thereby, Mie scattering can be suppressed. In Rayleigh scattering, compared to Mie scattering, the intensity of scattered light is very small, so that deterioration of color reproducibility can be prevented.

  In addition, it is known that particles dispersed in a liquid such as the adhesive 6 are difficult to uniformly disperse due to the influence of the particle surface potential (zeta potential), particularly when the particle diameter is 100 nm or less. ing. About this point, it is also possible to improve the dispersibility of a filler by modifying the filler with a silane coupling material having a hydrophilic or lipophilic functional group. Note that the present invention is not limited to this, and the filler dispersibility can be improved by appropriately combining other known methods.

In the present embodiment, the surface resistivity of the borosilicate glass that is the material of the optical filter 4 is as high as 10 ¹⁰ to 10 ¹² (Ω / □), and thus is easily charged with static electricity. For this reason, in order to make the optical filter 4 conductive so that the filler does not adhere to the optical filter 4 due to static electricity, such as when silicon is used as the filler, the surface of the filter. It is necessary to attach an antistatic coating to the surface.

  On the other hand, as described above, by setting the particle diameter of the filler contained in the adhesive 6 to be at least 1/10 or less of the shortest wavelength of the transmission wavelength of the optical filter 4, it is possible to avoid using a highly transmissive material. The filler can be optically transparent. Accordingly, unlike the imaging device described in Patent Document 1, it is not necessary to use silicon dioxide, which is a relatively highly transmissive substance, as a filler material, and the degree of freedom in selecting a filler material can be expanded.

In the present embodiment, the filler contained in the adhesive 6 includes, for example, conductive particles selected to have a center particle size of 20 nm and a dispersion of 3 nm, such as low-resistance metal fine particles such as aluminum and silver, and carbon nanotubes. By adding 10 wt%, it is possible to make the linear expansion coefficient appropriate and to add conductivity to the adhesive 6 without optically affecting it. As described above, this can also be realized by setting the particle diameter in such a range that the scattering of light colliding with the filler becomes Rayleigh scattering. Thus, generally as compared to SiO ₂ or the like which has been used in the filler can be reduced charging of the filler. For this reason, even if the filler drops off or scatters from the adhesive 6 and adheres to the components, manufacturing equipment, and tools of the imaging device 1 including the semiconductor imaging device 5, the Coulomb force due to the static electricity of the filler is small. Thus, the ionization efficiency of the ionizer is improved, and the adhering filler can be easily removed by a simple air blow.

  In addition, the filler contained in the adhesive 6 is made of conductive particles. As a result, the charge of the filler can be reduced. As a result, the filler contained in the nearby adhesive 6 can be provided without applying an antistatic coating to the optical filter 4. Does not adhere to the optical imaging area of the optical filter 4. As a result, the antistatic coating of the optical filter 4 can be eliminated, and the cost can be reduced.

  Further, in the assembling process or the inspection process of the semiconductor imaging device 5 and the three-dimensional substrate 2 or the optical filter 4, the charging of the filler can be reduced, so that charging on the incident surface of the semiconductor imaging device 5 can also be prevented. And dust can be prevented from adhering to the incident surface of the semiconductor image sensor 5. In addition, since charging does not easily occur on the incident surface of the semiconductor image sensor 5, even if filler or dust adheres to the incident surface of the semiconductor image sensor 5, the adhered filler or dust can be easily removed by air blow or the like. it can.

  According to the imaging apparatus 1 of the embodiment of the present invention, the particle diameter of the filler is set based on the transmission wavelength of the optical filter 4. Since light scattering is generally greatly related to the size of the particle and the wavelength of light hitting the particle, the light scattering by the filler can be adjusted by adjusting the relationship between the particle diameter of the filler and the transmission wavelength of the optical filter 4. Can be suppressed. Thereby, even if a filler adheres to the semiconductor image sensor 5, it is possible to reduce image quality deterioration due to scattering or dropping of the filler.

  Moreover, according to the imaging device 1 of the embodiment of the present invention, the particle diameter of the filler is substantially 1/10 or less of the shortest wavelength of the transmission wavelength of the optical filter 4, so that the optical filter 4 is bonded. Even if the filler contained in the agent scatters at the time of adhesion or drops off after the adhesive is cured and adheres to the semiconductor imaging device 5, the light impinging on the filler scatters according to the Rayleigh scattering law. In addition, the intensity of scattered light caused by the filler can be made very small, the filler can be made optically transparent, and as a result, the occurrence of black flaws can be suppressed. As a result, even if the filler adheres to the semiconductor imaging device 5, the output of the pixel to which the filler is attached can be obtained without correction using the output of the surrounding pixels, and the image quality deterioration due to the scattering or dropping of the filler is ensured. Can be reduced. Mie scattering occurs when the particle size approximates the wavelength of light, whereas Rayleigh scattering occurs when the particle size is smaller than the light wavelength. Therefore, by making the particle size of the filler substantially equal to or less than 1/10 of the shortest wavelength of the transmission wavelength of the optical filter 4, the light that collides with the filler is scattered with respect to the light in the transmission wavelength range of the optical filter 4. The region of Rayleigh scattering can be reliably obtained. Thereby, since Mie scattering can be suppressed, deterioration of color reproducibility can be prevented.

  Moreover, according to the imaging device 1 which concerns on embodiment of this invention, since the holding member has the structure which is the solid substrate 2, since each component of the imaging device 1 can be attached to the solid substrate 2, Workability during assembly is improved. In addition, since the components can be assembled and attached based on the three-dimensional board 2, the imaging device 1 can be assembled with high accuracy.

  Further, according to the imaging device 1 according to the embodiment of the present invention, since the filler has a spherical shape, the holding member to be bonded is obtained by eliminating the anisotropy of the adhesive 6 with respect to the temperature expansion. The anisotropy of (three-dimensional substrate 2) can be reduced. Thereby, the strength of the holding member (three-dimensional substrate 2) can be improved, and the imaging device 1 can be thinned.

  Moreover, according to the imaging device 1 which concerns on embodiment of this invention, the filler has the structure which has electroconductivity. In the present invention, since the particle diameter of the filler is set based on the size of the transmission wavelength of the optical filter 4, as described above, the intensity of the scattered light by the filler can be very small, and the filler is optically transparent. be able to. Thereby, for example, conductive particles such as metal particles and carbon can be used for the filler, without being limited to a material having relatively high permeability such as silicon dioxide. Therefore, it is possible to prevent the semiconductor image pickup element 5 from adhering. In addition, by using conductive particles as the filler contained in the adhesive, the charging of the filler can be reduced. As a result, the filler becomes difficult to adhere to the optical filter 4, so it is necessary to add an antistatic treatment to the optical filter 4. Disappears. Further, in the assembling process or the inspection process of the semiconductor imaging device 5 and the three-dimensional substrate 2 or the optical filter 4, the charging of the filler can be reduced, so that charging on the incident surface of the semiconductor imaging device 5 can also be prevented. And dust can be prevented from adhering to the incident surface of the semiconductor image sensor 5. In addition, since charging does not easily occur on the incident surface of the semiconductor image sensor 5, even if filler or dust adheres to the incident surface of the semiconductor image sensor 5, the adhered filler or dust can be easily removed by air blow or the like. it can.

  Further, according to the imaging device 1 according to the embodiment of the present invention, since the single-layer or multi-layer dielectric film is formed on the incident surface of the optical filter 4, the optical filter 4. It is possible to prevent loss of light at the incident surface and improve the transmittance.

  The embodiments of the present invention have been described above by way of example, but the scope of the present invention is not limited to these embodiments, and can be changed or modified according to the purpose within the scope of the claims. is there.

  In the description of the above embodiment, the imaging device that captures visible light has been described. However, the particle size of the filler is also reduced in the optical filter for an imaging device that captures light other than visible light such as near infrared light and near ultraviolet light. It is possible to apply the idea of the present invention of setting based on the transmission wavelength of 4, thereby producing the same effect as described above.

  As described above, the present invention has an effect that image quality deterioration due to scattering or dropping off of filler can be reduced, and is useful for an imaging apparatus using a semiconductor imaging element.

Sectional drawing of the imaging device in embodiment of this invention The perspective view of the image pick-up device in an embodiment of the invention The figure which shows the spectral characteristic of the optical filter used for the imaging device in embodiment of this invention Schematic diagram showing an example of the color arrangement of pixels in the semiconductor imaging device 5 Diagram showing the principle of Rayleigh scattering Diagram showing the relationship between scattered light intensity and particle size

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging device 2 Three-dimensional board | substrate 2a Lens barrel part 2b Bottom part 3 Aspherical lens 4 Optical filter 5 Semiconductor image pick-up element 6 Adhesive 7 Diaphragm 10 Flexible printed circuit board (FPC)

Claims (6)

A semiconductor imaging device for converting incident light into an electrical signal;
An optical filter disposed opposite to the incident surface of the semiconductor imaging device;
A holding member for holding the optical filter by bonding using an adhesive containing a filler,
The particle diameter of the filler is set based on the transmission wavelength of the optical filter.   The imaging device according to claim 1, wherein a particle diameter of the filler is substantially 1/10 or less of a shortest wavelength of a transmission wavelength of the optical filter.   The imaging apparatus according to claim 1, wherein the holding member is a three-dimensional substrate.   The imaging device according to claim 1, wherein the filler has a spherical shape.   The imaging apparatus according to claim 1, wherein the filler has conductivity.   6. The imaging apparatus according to claim 1, wherein a single-layer or multi-layer dielectric film is formed on an incident surface of the optical filter.