JP2013157606A - Solid state imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent light color mixing between adjacent micro lenses, and to suppress the deterioration of matching accuracy of a parallax image group.SOLUTION: A solid state imaging device includes: an imaging element; a first optical system 40 for imaging a subject on an imaging surface; a second optical system including a microlens array having a plurality of microlenses 10 provided corresponding to a plurality of pixel blocks, and re-imaging an image formed on the imaging surface on the pixel blocks corresponding to the individual microlenses; a first filter 12 provided corresponding to the plurality of microlenses on the second optical system side, and having a plurality of first color filter; and a second filter 6 provided on the imaging element side, and having a plurality of second color filters corresponding to the plurality of first color filters of the first filter. The first and second filters are configured so as to shift in a peripheral direction of an imaging area, toward a peripheral portion of the imaging area.

Description

  Embodiments described herein relate generally to a solid-state imaging device that simultaneously acquires a visible image and distance information.

  As an imaging technique capable of obtaining a depth direction distance as two-dimensional array information, various methods such as a technique using a reference light and a stereo distance measuring technique using a plurality of cameras are being studied. In particular, in recent years, there has been an increasing need for relatively inexpensive products as new input devices for consumer use.

  Therefore, an imaging apparatus having a compound eye configuration that has an imaging lens has been proposed as a configuration that can obtain multiple parallaxes with multiple eyes and suppress a reduction in resolution (for example, see Non-Patent Document 1). This imaging apparatus has an imaging system lens, for example, and a plurality of optical systems are arranged as a re-imaging system optical system between the imaging system lens and the imaging device. For example, as a plurality of optical systems, a microlens array in which a large number of microlenses are formed on a plane is used. Below each microlens, a plurality of pixels are provided at corresponding positions to acquire the image. The image formed in the imaging lens is re-imaged on the image sensor by the re-imaging microlens, and the re-imaged single-eye image is shifted in viewpoint by the amount of parallax that exists depending on the position of the microlens The resulting image. By subjecting a group of parallax images obtained from a large number of microlenses to image processing, it is possible to estimate the distance of the subject based on the principle of triangulation, and to reconstruct it as a two-dimensional image by performing splicing image processing. It is also possible to do. As an example of image processing for estimating the distance of a subject, general-purpose stereo image processing that compares images and obtains a portion where the same point of the subject is imaged by an image matching method or the like can be used.

K. Fife, A. E. Gamal, and H. Wong, “A 3D multi-aperture image sensor architecture,” Custom Integrated Circuits Conference, pp. 281-284, Sep. 2006.

  However, there is a problem that light color mixing between adjacent microlenses reduces the matching accuracy of the parallax image group.

  Embodiments of the present invention provide a solid-state imaging device that can prevent light color mixing between adjacent microlenses and suppress a decrease in matching accuracy of a parallax image group.

  The solid-state imaging device according to the present embodiment includes an imaging element that includes an imaging region that is formed on a semiconductor substrate and includes a plurality of pixel blocks each including a plurality of pixels, and a first optical that images a subject on an imaging plane. A microlens array having a system and a plurality of microlenses provided corresponding to the plurality of pixel blocks, and the image formed on the imaging plane is re-converted into pixel blocks corresponding to the individual microlenses. A second optical system that forms an image; a first filter that is provided on the second optical system side corresponding to the plurality of microlenses, and that has a plurality of first color filters; A second filter having a plurality of second color filters corresponding to the plurality of first color filters of the first filter and performing an image matching process between pixel blocks of the same color A processing unit that obtains a distance to the subject, and the first and second color filters move toward the periphery of the imaging region in the peripheral direction of the imaging region. It is characterized by being configured to shift.

1 is a cross-sectional view illustrating a solid-state imaging device according to a first embodiment. The figure explaining the relationship between two color filters. The figure explaining the case where two color filters are Bayer arrangement. The figure explaining the color-mixing prevention effect. The figure explaining the color-mixing prevention effect. The figure explaining the shift amount of a color filter. 7A and 7B are diagrams for explaining the shift amount of the color filter. The figure explaining the method of acquiring distance information from an optical image. The figure which shows the dependence of the distance of the imaging surface regarding ML and the ML main surface. The figure explaining the optical image acquired by the solid-state imaging device of 1st Embodiment. The figure explaining the film thickness and color mixing prevention effect of a color filter. The figure explaining the film thickness and color mixing prevention effect of a color filter. 13A to 13E are views for explaining a method of manufacturing the solid-state imaging device according to the first embodiment. 14A to 14C are views for explaining a method of manufacturing the solid-state imaging device according to the first embodiment. FIGS. 15A to 15C are diagrams illustrating the manufacture of a color filter and a microlens. Sectional drawing which shows the solid-state imaging device by 2nd Embodiment. Sectional drawing which shows the solid-state imaging device by 3rd Embodiment.

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

  The solid-state imaging device according to the present embodiment includes an imaging element that includes an imaging region that is formed on a semiconductor substrate and includes a plurality of pixel blocks each including a plurality of pixels, and a first optical that images a subject on an imaging plane. A microlens array having a system and a plurality of microlenses provided corresponding to the plurality of pixel blocks, and the image formed on the imaging plane is re-converted into pixel blocks corresponding to the individual microlenses. A second optical system that forms an image; a first filter that is provided on the second optical system side corresponding to the plurality of microlenses, and that has a plurality of first color filters; A second filter having a plurality of second color filters corresponding to the plurality of first color filters of the first filter and performing an image matching process between pixel blocks of the same color And a, a processing unit for determining the distance to the object. The first and second filters are configured such that the first and second color filters are shifted in the peripheral direction of the imaging region as they go to the peripheral part of the imaging region.

(First embodiment)
A solid-state imaging device according to the first embodiment is shown in FIG.

  In the solid-state imaging device according to the present embodiment, a plurality of pixels 4 having photodiodes are formed on a semiconductor substrate 2, and a driving / reading circuit that drives these pixels 4 and reads signals from these pixels 4 (Not shown) is provided. On the upper part of the pixel 4, when p and q are natural numbers, for example, a color filter 6 is formed for every p × q pixel blocks. A microlens 8 for condensing pixels may be formed for each pixel on the color filter 6.

  Above the color filter 6, a visible light transmitting substrate 14 on which the imaging microlens array 10 and the color filter 12 are formed and which transmits visible light is provided. The visible light transmitting substrate 14 is bonded to the semiconductor substrate 2 by a spacer 9 made of a resin material provided around the imaging region where the pixels 4 are formed. The alignment when the semiconductor substrate 2 and the visible light transmitting substrate 14 are bonded is performed with reference to an alignment mark or the like. The visible light transmitting substrate 14 may be a material that cuts unnecessary infrared light, for example, or may be formed with a film that cuts infrared light. When the visible light transmitting substrate 14 is bonded to the semiconductor substrate, the color filters 6 and 12 are bonded so that the combination of colors is the same. In addition, the color interval of the color filter 6 is configured to be narrower than the color interval of the color filter 12.

  The semiconductor substrate 2 is provided with a read electrode pad 22 of the pixel 4, and a through electrode 24 penetrating the semiconductor substrate 2 is formed below the electrode pad 22. The semiconductor substrate 2 is electrically connected to the chip 30 through the through electrode 24 and the bump 26. The chip 30 is formed with a drive processing circuit that drives the imaging apparatus and processes the read signals.

  Further, an imaging lens 40 is provided above the visible light transmitting substrate 14, and this imaging lens 40 is attached to a lens barrel 42, and this lens barrel 42 is attached to a lens holder 44. The lens holder 44 is bonded onto a peripheral region of the visible light transmitting substrate 14 where the color filter 12 is not provided. When the lens 40 is attached, the focal length of the lens 40 may be adjusted from the relationship between the pressing pressure and the output image. A light shielding cover 50 for blocking unnecessary light is attached around the semiconductor substrate 2, the visible light transmitting substrate 14, and the chip 30. The light shielding cover 50 is provided with a module electrode 52 that electrically connects the chip 30 and the outside.

(Color mixing prevention by color filter)
The color mixing prevention function by the color filter in the solid-state imaging device of the present embodiment configured as described above will be described with reference to FIGS.

  The correspondence between the color filters 6 and 12 and the pixel area is shown in FIG. The microlens 10 and the color filters 6 and 12 are arranged in each pixel block 5R and 5B, the color filter 12 is arranged on the microlens 10 side, and the color filter 6 is arranged on the pixel block side 5R and 5B side that performs photoelectric conversion. . The light beam that has passed through the imaging lens 40 forms an image on the imaging surface 60 and then enters the color filter 12. Each color is filtered on each of the microlens 10 side and the pixel blocks 5R and 5B side, and mixed color components of different colors of adjacent pixels are absorbed by the color filters 6 and 12 and eliminated. The pixel block 5R indicates a pixel block that detects red, and the pixel block 5B indicates a pixel block that detects green. That is, the light ray 62R representing red passes through the imaging lens 40 and forms an image on the imaging surface 60, then passes through the red transmission filter of the color filter 12 and the red transmission filter of the color filter 6, and is taken into the pixel block 5R. It is. Similarly, the light ray 62G representing green is transmitted through the imaging lens 40 and formed on the imaging surface 60, and then passes through the green transmission filter of the color filter 12 and the green transmission filter of the color filter 6, and enters the pixel block 5B. It is captured.

  As the color arrangement for each pixel block, for example, a primary color Bayer arrangement may be used as shown in FIG. It is more effective to prevent color mixing when different color filters are used for adjacent pixels.

The effect of preventing color mixture when the color filters 6 and 12 are in a Bayer array will be described with reference to FIGS. When passing through the color filters 6, 12, only the combination having the same color causes the light rays to pass through the color filter 12 and the color filter 12 and form an image on the pixel block 5. For example, the principal ray 62Rm red incident at angle theta _R on the imaging lens 40, passes through the red transmission filter of the color filter 12, transmitted through the red transmission filter of the color filter 6 via the micro-lens 10. Similarly, the red light beam 62Rc around the principal light beam 62Rm also passes through the red transmission filter of the color filter 6 after passing through the red transmission filter of the color filter 12.

In addition, as shown in FIG. 5, after the green principal ray 62Gm incident on the imaging lens 40 at an incident angle θ _G passes through the green transmission filter of the color filter 12, the color filter 6 passes through the micro lens 10. Transmits through the green transmission filter. However, as shown in FIG. 5, when there is green light that passes through the green transmission filter of the color filter 12 and passes through the red transmission filter of the color filter 6, for example, diffusely reflected green light 62 Gr, this becomes a color mixture component. However, the green light 62Gr attenuates in the red transmission filter of the color filter 6. For this reason, it becomes possible to prevent light from entering the photodiode 4 in the pixel block 5 as an optical signal, and color mixing can be prevented.

(Color filter shift amount)
Next, the shift amounts of the color filters 6 and 12 in the solid-state imaging device according to the present embodiment will be described.

  The color filters 6 and 12 are arranged so as to be shifted in the peripheral direction by the peripheral part of the imaging region, and the corresponding relationship is shown in FIGS. 6, 7 (a), and 7 (b). 6 is a perspective view showing the color filters 6 and 12, FIG. 7A is a cross-sectional view taken along a diagonal plane of the color filter 6 shown in FIG. 6, and FIG. It is an enlarged view of the broken-line part shown to 7 (a).

As shown in FIG. 7A, the red light transmission filter 6R in the color filter 6 and the red light transmission filter 12R in the color filter 12 have a corresponding relationship, and enter the imaging lens 40 at an incident angle θ. After 62 forms an image on the imaging surface 60, it is assumed to transmit through the red transmission filter 12R and the red transmission filter 6R. The image height Y of the subject on the imaging surface 60 is, when the subject is at infinity, where f is the focal length of the imaging lens 40,
tan θ = Y / f
It is represented by Therefore, the centers of the red transmission filter 6R and the red transmission filter 12R are shifted by the shift amount α. This shift amount α is expressed by the following equation, where D is the distance between the color filter 6 and the color filter 12 (the distance between the color filter 6 and the microlens 10 when the microlens 10 is present). It is represented by
α = D × tan θ = D × Y / f
Here, the incident angle θ of the chief ray 62 is maximized at the outermost part of the imaging region, but the incident angle θ _max of the chief ray 62 at that time is considered. For example, if the chief ray incident angle θ is a standard half angle of view of 30 degrees with a portable or compact camera and D = 1 mm, the shift amount α at the four corners of the imaging region is 0.577 mm.

  The shift amount except for the outermost part is determined by the incident angle θ of the principal ray 62 at each position. Since the incident angle θ of the chief ray 62 is 0 degree at the center of the imaging region, the shift amount α may be zero, and θ increases toward the outer edge, so it is preferable to increase the shift amount α.

(Method to obtain distance information from optical image)
Next, a method for acquiring distance information from an optical image in the solid-state imaging device according to the present embodiment will be described with reference to FIG. For simplification, this time, only the formula of the optical axis approximation range is described.

ここでｆは結像レンズ４０の焦点距離、Ａは結像レンズ４０の物体側主面４０ａから被写体までの距離、Ｂは結像レンズ４０の像側主面４０ａから結像面６０までの距離を示す。結像レンズ４０の像倍率（横倍率）は下式で表される。

By the optical imaging system (imaging lens) 40, the principal ray from the subject and its cognate rays satisfy the relationship of the formula (1) on the imaging plane 60 determined by the focal length of the imaging optical system and the subject distance. To form an image.

Here, f is the focal length of the imaging lens 40, A is the distance from the object-side main surface 40a of the imaging lens 40 to the subject, and B is the distance from the image-side main surface 40a of the imaging lens 40 to the imaging surface 60. Indicates. The image magnification (lateral magnification) of the imaging lens 40 is expressed by the following equation.

ここで、ｇはＭＬ１０の焦点距離、ＣはＭＬ１０の物体側主面１０ａから結像面６０までの距離、ＤはＭＬ１０の像側主面１０ａから撮像素子面までの距離を示す。このとき、結像系４０による像倍率は次の式（３）によって表される。

ここで、幾何関係により式（５）のＥを導入する。光学系４０が単焦点光学系の場合、Ｅは一定の関係となる。
Ｅ＝Ｂ＋Ｃ （５）
ここで、比較する個眼間を２個選択した場合の、個眼間距離Ｌ_ＭＬと片側の像ずれ量Δ／２は式（６）で表される。

ここで、Ｄ_０は基準被写体が位置Ａ_０のときの再結像距離を示す。 The image on the imaging surface 60 is again formed on the imaging element surface on which the pixels 4 are provided by a microlens (hereinafter also referred to as ML) 10 disposed below the imaging surface 60. The image of ML10 is expressed by the following equation.

Here, g indicates the focal length of the ML 10, C indicates the distance from the object-side main surface 10 a of the ML 10 to the imaging surface 60, and D indicates the distance from the image-side main surface 10 a of the ML 10 to the imaging element surface. At this time, the image magnification by the imaging system 40 is expressed by the following equation (3).

Here, E in Equation (5) is introduced due to the geometric relationship. When the optical system 40 is a single focus optical system, E has a certain relationship.
E = B + C (5)
Here, the distance between the single eyes L _ML and the image shift amount Δ / 2 on one side when the two single eyes to be compared are selected are expressed by Expression (6).

Here, D ₀ indicates the re-imaging distance when the reference subject is at the position A ₀ .

Thus, the amount of change of each parameter with respect to the movement of the subject (change of A) is shown. Parameters with subscript _{0 at} the lower right, such as A ₀ , are the initial values of the corresponding parameters. The change from the initial value of each parameter is shown by an equation.

If the amount of change in D is expressed by M (imaging lens magnification) from the equations (1) to (5), the relationship shown in the following equation (7) is obtained.

Further, from the expressions (1), (2), (6), and (7), the distance A of the subject and the image shift amount Δ have the relationship shown in the following expression (8).

The deviation amount Δ and the magnification M have the relationship shown in the following equation (9).

ここで、精度（Ａの変化に対するΔの変化）は、下式で表される。

When the subject A is located far away, that is, A → ∞, M → 0, and the shift amount Δ converges to the value shown in the following equation (10).

Here, the accuracy (change in Δ with respect to change in A) is expressed by the following equation.

  Since Expression (11) indicating the above accuracy includes M (= B / A), the accuracy has distance dependency.

Next, based on the above relationship, it is assumed how much deviation Δ is generated by the movement of the subject A assuming actual optical parameters. Assume the following optical parameters:
Imaging lens focal length f: 7 mm or 42 mm
ML focal length g: 682 μm
ML arrangement pitch: 300 μm
Image sensor pixel pitch: 4.3 μm
The initial position _{A 0} indicates the precision in the case of a 0.3 m.
Here, A ₀ means the closest subject distance (the limit of the closer depth of field) in the range where the focus is achieved in a certain focus position state.

Dependence of the C ₀ arrangement distance (distance between the imaging surface 60 and the ML main surface 10a) on the shift amount when the focal length f of the imaging lens is 7 mm or 42 mm and the initial focusing position A _{0 is} 0.3 m. Is shown in FIG. From the deviation amount Δ shown in Equation (10), the smaller the f, the larger the parallax convergence distance Δ. When this converged deviation amount Δ / 2 becomes larger than the pixel block interval, it becomes a range over region where crosstalk occurs between MLs. Therefore, the relationship between the convergence distance and ML is one of design guidelines.

  FIG. 10 shows a relationship between a subject and an optical image acquired by the solid-state imaging device of the present embodiment. A reverse image of the subject 100 is formed on the image plane 60 by the joint optical system (joint lens) 40. Each microlens 10 is in a state where the image on the imaging plane 60 is viewed from a close distance, and a group of parallax images that overlap each other is formed on each pixel block 5R, 5G. Since the re-imaged image at this time is inverted again, it becomes an erect image. The image of the image plane 60 formed by the culmination optical system 40 is reduced and picked up by the microlens 10. This reduction magnification determines the degree of optical resolution degradation.

  Next, the film thickness and color mixing prevention effect of the color filters 6 and 12 will be described with reference to FIGS. FIG. 11 is a graph showing the effect of preventing color mixing in the color filters 6 and 12. Consider a case where the total film thickness of the color filters 6 and 12 is 1 μm, the color filter 12 is divided into a thickness of 0.5 μm, and the film thickness of the color filter 6 is divided into 0.5 μm. Here, blue (B), green (G), and red (R) are considered in FIG. 11, and the following (1) to (5) will be described separately. (1) G filter → G light passing through G filter, (2) G filter → B light passing through G filter, (3) G filter → R light passing through G filter, (4) G filter → G light passing through R filter Light, (5) R light → G light passing through the G filter. Here, cases (4) and (5) are color mixture components between adjacent pixel blocks.

  As the color filter characteristics, the G light that has been transmitted through the G filter as a signal component for a total of 1 μm decreases in intensity after transmission to approximately 80%, and passes through the G filter that is a mixed color component. It is assumed that after being absorbed by the filter, it decreases to about 8% after 1 μm transmission. In the case of the above assumption, when calculation is performed for the color mixture from adjacent pixels, that is, cases (4) and (5), the color mixture component after transmission is reduced to 20%.

  FIG. 12 shows a graph showing the effect of preventing color mixing when the film thickness is increased by the color filters 6 and 12. When the total film thickness of the color filters 6 and 12 is 1.5 μm and the thicknesses are respectively set to 0.75 μm and 0.75 μm, the total film can be reduced to the crosstalk component when passing 1 μm. It can be seen that the thickness should be increased by a factor of 1.5. The brightness drop at this time is suppressed to 8%.

(Production method)
Next, a method for manufacturing the solid-state imaging device of the present embodiment will be described with reference to FIGS. 13 (a) to 14 (c).

  First, as shown in FIG. 13A, a pixel 4 made of a photodiode and a drive and readout circuit (not shown) are formed on a semiconductor substrate 2. A color filter pattern 6 is formed for each pixel block. A transparent planarizing resin or a light shielding film 7 is formed on unnecessary portions of the color filter 6. A pixel condensing microlens 8 may be formed for each pixel on the color filter 6. In addition, an upper surface of the semiconductor substrate is opened, and an electrode pad 22 is provided on the bottom surface of the opening.

  Subsequently, a spacer resin 9 is applied around the imaging region where the pixels 4 are formed, and an opening is formed by photolithography above the imaging region where the pixels 4 are formed (FIG. 13B). 13 (c)).

  Next, the visible light transmitting substrate 14 on which the microlens array 10 and the color filter 12 are formed is bonded to the semiconductor substrate 2 using the alignment mark or the like above the semiconductor substrate 2 (FIG. 13D). The visible light transmitting substrate 14 may be a material that cuts unnecessary infrared light, for example, or may be formed with a film that cuts infrared light. At the time of this joining, the color filters 6 and 12 are joined so that the color combinations are the same.

  Next, a penetrating electrode 24 is formed below the pixel readout electrode pad 22 (FIG. 13E). Subsequently, the semiconductor substrate 2 is driven through the bumps 26 and bonded to the chip 30 on which the processing circuit is formed (FIG. 14A). Above the pixel 4, the lens holder 44 and the imaging lens 40 attached to the lens barrel 42 are attached to the semiconductor substrate 2 by bonding (FIG. 14B). At the time of attachment, the focal length of the conspicuous lens 40 may be adjusted from the relationship between the pressing pressure and the output image. Next, each unit module is separated, and a light shielding cover 50 for blocking unnecessary light is attached to the periphery, thereby completing the solid-state imaging device (FIG. 14C).

  Next, a method for manufacturing a color filter and a microlens will be described with reference to FIGS. 15 (a) to 15 (e).

  The microlens array is created using photolithography and etching techniques, which are semiconductor manufacturing techniques used for general purposes. Although the case where the color filter 12 and the microlens 10 are formed on the visible light transmitting substrate 14 will be described as an example, the case where the color filter 6 and the microlens 8 are formed on the semiconductor substrate 2 can be similarly performed.

  First, a visible light transmitting substrate 14 is prepared, and a color filter 12 is formed on the visible light transmitting substrate 14 by photolithography (FIGS. 15A and 15B). When the color filter 12 is arranged in a Bayer arrangement of blue, green, and red, the process of applying a pigment or dye resin of each color and patterning by photolithography is repeated.

  Next, a photosensitive resin for re-imaging microlens is applied on the color filter 12 (FIG. 15C), and the resin having the same period as the arrangement period of the pixel block and the color filter 6 by using a photolithography technique. A pattern is formed (FIG. 15D).

  Next, the resin is thermally deformed by heat-treating the substrate, a lens-shaped pattern is created, and the microlens 10 is formed (FIG. 15E).

  In the above, the microlens array is made of a photosensitive transparent resin. For example, after a resin microlens pattern is similarly formed on a glass substrate, the glass substrate and the photoresist are evenly distributed by reactive ion etching or the like. The resin shape may be transferred to the glass substrate by anisotropic etching. In this case, since the microlens is formed first, the color filter is formed on the microlens or on the back side of the substrate.

(Image reconstruction)
Next, image processing for obtaining a normal pixel image and distance information from an acquired image by the solid-state imaging device according to the present embodiment will be described. Monochromatic (red, blue, or green) images obtained for each pixel block each have a parallax corresponding to the position of the microlens. For the parallax, vertical and horizontal parallax information can be obtained by performing an image matching process between two green pixel blocks in one Bayer array unit. In the Bayer array, the remaining blue and red are orthogonal to the two diagonal green pixels, so the remaining red and blue parallax amounts are calculated from the parallax components obtained from the two green images. it can. Since these parallax amounts include distance information, the subject distance can be estimated from the parallax amounts obtained by the image matching processing. Further, by reconstructing blue and green painter images based on the amount of parallax, it is possible to reconstruct a two-dimensional image as obtained with a normal camera.

  As the image matching process, for example, a well-known template matching method for examining the degree of similarity or difference between two images can be used. Further, when calculating the displacement position more precisely, the degree of similarity or similarity obtained for each pixel unit is interpolated with a continuous fitting function or the like to obtain the subpixel position that gives the maximum or minimum of the fitting function. In addition, the displacement amount can be obtained with higher accuracy.

  As described above, in the present embodiment, each color is filtered on the microlens 10 side and the pixel block side, and adjacent color mixture components are absorbed and eliminated by the color filters 6 and 12. At that time, the color filters 6 and 12 are shifted toward the periphery of the imaging region toward the periphery of the imaging region, depending on the angle of the principal ray for the microlens 10 of the light rays incident on the microlens array 10 from the imaging surface 60. This effectively prevents color mixing and increases the effective imaging area of each microlens 10.

  According to the present embodiment, it is possible to prevent light color mixing between adjacent microlenses and suppress a decrease in matching accuracy of a parallax image group.

  Further, by shifting the color filters 6 and 12 toward the periphery of the imaging region toward the periphery of the imaging region, it is possible to minimize the amount of vignetting of light rays having a large incident angle at the periphery. The adjustment of the shift amount can be appropriately designed according to the characteristics of the image forming angle of the image forming lens 40, and may be reflected in the mask design of the color filter 6 and the color filter 12, so that the design is flexible.

  In addition, no additional parts such as shutter parts that prevent color mixture from entering the adjacent individual eyes or barrier ribs with a concavo-convex structure are required, so that cost can be reduced and the yield during assembly due to part alignment errors, etc. A decrease can be prevented.

  In addition, since the color filter 12 and the microlens 10 can be formed on the transparent wafer 14 using a semiconductor process that is normally used, a solid-state imaging device can be assembled on a wafer scale.

  In addition, when one pixel is miniaturized to the optical limit of the imaging lens 40, particularly, a long wavelength such as red has a low absorption coefficient in a silicon photodiode, and therefore, color mixing with adjacent pixels is a problem. However, by arranging color filters for each pixel block instead of for each pixel as in this embodiment, adjacent pixels in the pixel block photoelectrically convert the same color component, thus preventing crosstalk between photodiodes. can do.

  In addition, pigment dispersion resists are often used for color filters, but the pixel size and pixel size of pigments are about the same due to pixel miniaturization, and the spectral characteristics of the color filter above each pixel due to unevenness in the application of pigment particles. There is a problem that characteristic unevenness occurs. However, by arranging a color filter for each pixel block as in this embodiment, the color information can be averaged at adjacent pixel portions, and therefore, spectral dispersion due to unevenness is achieved rather than arranging a pixel filter for each pixel. The characteristic deterioration can be prevented.

  In addition, the imaging lens has a complicated design such as a plurality of lenses and an aspherical lens in order to minimize chromatic aberration. However, by providing a color filter and a microlens for each pixel block, the imaging characteristics of the microlens ( (Focal length) can be changed for each color, so that the chromatic aberration requirement on the lens side can be relaxed and the cost of the lens can be reduced.

  Further, the size of the solid-state imaging device can be reduced to the same level as the imaging element chip. Since the through electrode is used for extraction to the outside, no bonding wire is required. For this reason, after the photosensitive region is sealed with the transparent substrate 14 on which the microlens array 10 and the color filter 12 are formed, the attached dust becomes a problem that the dust attached to the surface of the transparent substrate 14 becomes a problem. However, in the present embodiment, the surface of the transparent substrate 14 and the photosensitive region have a distance determined by the thickness of the transparent substrate 14 and the thickness of the adhesive, and are in the middle of the optical path imaged by the lens. An image is formed on the upper side in a defocused state, and the degree of influence on black scratches can be greatly reduced as compared with dust on the photosensitive region of a conventional solid-state imaging device.

(Second Embodiment)
Next, a solid-state imaging device according to the second embodiment is shown in FIG. The solid-state imaging device of the second embodiment has a configuration in which the microlens 10 and the color filter 12 of the solid-state imaging device of the first embodiment shown in FIG. 1 are replaced with a microlens 10A having spectral performance. The micro lens 10A also serves as a color filter and can be made of a pigment dispersion resist.

  This 2nd Embodiment can also have the same effect as a 1st embodiment.

(Third embodiment)
Next, a solid-state imaging device according to the third embodiment is shown in FIG. The solid-state imaging device of the third embodiment has a configuration in which the macro lens 10 of the solid-state imaging device of the first embodiment shown in FIG. 1 is replaced with a microlens 10B. The micro lens 10B is formed on the image forming optical system (image forming lens) 40 side of the color filter 12, and has a configuration in which the convex portion faces the image forming optical system (image forming lens) 40.

  This third embodiment can also achieve the same effects as the first embodiment.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof as well as included in the scope and gist of the invention.

2 Semiconductor substrate 4 Pixel 5R Pixel block 5B Pixel block 6 Color filter 8 Micro lens 9 Spacer resin 10 Micro lens 12 Color filter 14 Visible light transmitting substrate 22 Electrode pad 24 Through electrode 26 Bump 30 Chip 50 Light shielding cover 52 Module electrode

Claims (8)

An imaging device including an imaging region formed on a semiconductor substrate and having a plurality of pixel blocks each including a plurality of pixels;
A first optical system for imaging a subject on an imaging plane;
Including a microlens array having a plurality of microlenses provided corresponding to the plurality of pixel blocks, and re-images an image formed on the imaging plane onto a pixel block corresponding to each microlens A second optical system;
A first filter provided on the second optical system side corresponding to the plurality of microlenses and having a plurality of first color filters;
A second filter provided on the image sensor side and having a plurality of second color filters corresponding to the plurality of first color filters of the first filter;
A processing unit for obtaining a distance to the subject by performing an image matching process between pixel blocks of the same color;
With
The first and second filters are configured so that the first and second color filters are shifted in the peripheral direction of the imaging region as they go to the peripheral part of the imaging region. apparatus.   2. The solid-state imaging device according to claim 1, wherein the second color filter of the same color of the second filter corresponds to each of the first color filters of the first filter. The shift amount α of the color filter is defined as follows. The incident angle of a light beam incident on the corresponding microlens from the imaging plane is θ, and the distance between the first and second filters is D.
α = D × tan θ
The solid-state imaging device according to claim 1, wherein the solid-state imaging device is expressed by:   4. The solid-state imaging device according to claim 1, wherein the second optical system is provided on the imaging element side with respect to the first filter. 5.   4. The solid-state imaging device according to claim 1, wherein the second optical system is provided on the first optical system side with respect to the first filter. 5.   The other microlens array including the other microlens corresponding to each pixel is provided on the opposite side to the image sensor with respect to the second filter. The solid-state imaging device described in 1.   The solid-state imaging device according to claim 1, wherein each of the first and second color filters includes a red, green, and blue color filter.   Each of the first and second filters is a Bayer array, and the distance to the subject is obtained by performing an image matching process between two green pixel blocks that exist in one unit of the Bayer array. The solid-state imaging device according to claim 1.

Images