JP5329348B2 - Solid-state imaging device and imaging apparatus using the same - Google Patents

Description

  The present invention relates to a solid-state imaging device and an imaging device using the same, and more particularly to a solid-state imaging device in which a plurality of pixels for detecting a phase difference signal for focus detection are arranged on an imaging surface and an imaging device using the same.

  2. Description of the Related Art A solid-state imaging device used for a digital camera or the like has a two-dimensional array of pixels each having a photoelectric conversion element (light receiving element) for generating a signal charge corresponding to the amount of received subject light. On the upstream side of the optical path of these pixels, a microlens for condensing the light incident on the light receiving surface of the solid-state imaging device on the light receiving device is arranged for each pixel.

  Here, as a method of detecting a phase difference signal using a solid-state imaging device, some of the two-dimensionally arranged pixels are used as phase difference detection pixels, and this phase difference detection pixel is detected. A method is known in which a microlens of a pixel is arranged while being reduced and moved (shifted) with respect to a light receiving surface.

  For example, Patent Document 1 describes a technique for detecting a phase difference signal by disposing a micro lens with respect to a light receiving element. According to this technique, the adjacent first and second image sensors can be given light-receiving state selectivity depending on the input angle, so that the in-focus state is determined from the phase of the output signals of the first and second image sensors. Can be detected.

Patent No. 2959142

  However, if the microlens of the phase difference detection pixel is reduced or shifted as described above, it is adjacent to the phase difference detection pixel due to leakage light from the gap between the microlenses or the shape change of the microlens of the adjacent pixel. This causes a problem that the amount of light received by the pixels to be increased. As a result, color mixture and sensitivity unevenness occur in the photographic pixels adjacent to the phase difference detection pixels. However, Patent Document 1 does not take any consideration into this problem.

  The present invention has been made in view of such circumstances, and a solid-state imaging device that prevents color mixing and sensitivity unevenness by preventing an increase in the amount of light received by pixels adjacent to a phase difference detection pixel, and imaging using the same An object is to provide an apparatus.

  In order to achieve the above object, the solid-state imaging device according to claim 1 is a photoelectric conversion device that converts received light into a signal charge, and is arranged in a two-dimensional manner at equal intervals in a row direction and a column direction. A plurality of photoelectric conversion elements and a plurality of microlenses arranged on the upstream side of the corresponding optical path of the corresponding photoelectric conversion elements, respectively, for condensing the light received through the photographing lens on the corresponding photoelectric conversion elements In the solid-state imaging device including a plurality of microlenses, the photoelectric conversion element includes a first photoelectric conversion element for obtaining an image signal for forming a captured image, and an autofocus detection signal of at least a phase difference detection method. A second photoelectric conversion element and a third photoelectric conversion element for obtaining a first photoelectric conversion corresponding to light passing through the entire lens pupil of the photographing lens. A first microlens to be received by a child, a first microlens disposed at a predetermined position with respect to a corresponding photoelectric conversion element, and a region obtained by dividing a lens pupil of the photographing lens by a predetermined center line A second microlens that causes the corresponding second photoelectric conversion element to receive light passing through one of the regions, and is formed smaller than the first microlens and corresponds to the corresponding photoelectric conversion element A second microlens arranged to be shifted in the first direction from the predetermined position, and a third microlens that causes the corresponding third photoelectric conversion element to receive light passing through the other region among the divided regions. A lens formed smaller than the first microlens and shifted from the predetermined position to a direction opposite to the first direction with respect to a corresponding photoelectric conversion element. A gap between the plurality of microlenses, and a gap formed around the second microlens or the third microlens. A predetermined shape is formed to reduce an increase in the amount of light received by the first photoelectric conversion element due to incident light.

  According to the first aspect of the present invention, the gap formed by shifting the second microlens and the third microlens smaller than the first microlens is arranged in the gap. Since the predetermined shape for reducing the increase in the amount of light received by the first photoelectric conversion element due to the incident light is formed, an increase in the amount of light received by the pixels adjacent to the phase difference detection pixels can be prevented.

  According to a second aspect of the present invention, in the solid-state imaging device according to the first aspect, the predetermined shape is a fourth microlens shape for suppressing the spread of the first microlens. .

  Thereby, since the spread of the first microlens can be suppressed, it is possible to prevent an increase in the amount of light received by the pixels adjacent to the phase difference detection pixels.

  According to a third aspect of the present invention, in the solid-state imaging device according to the first aspect, the predetermined shape is a shape for preventing incident light to the gap from being condensed on an adjacent photoelectric conversion element. .

  Thereby, the incident light to the gap can be prevented from being condensed on the adjacent photoelectric conversion element, so that an increase in the amount of light received by the pixel adjacent to the phase difference detection pixel can be prevented.

  4. The solid-state imaging device according to claim 3, wherein the predetermined shape is a convex lens shape having a predetermined curvature for condensing incident light to the gap at a position other than the photoelectric conversion element. It is characterized by being.

  Thereby, since the incident light to the gap can be condensed at a position other than the photoelectric conversion element, an increase in the amount of light received by the pixels adjacent to the phase difference detection pixels can be prevented.

  According to a fifth aspect of the present invention, in the solid-state imaging device according to the fourth aspect, a plurality of the convex lens shapes are formed in one gap.

  Thereby, since the incident light to the gap can be condensed at a position other than the photoelectric conversion element, an increase in the amount of light received by the pixels adjacent to the phase difference detection pixels can be prevented.

  According to a sixth aspect of the present invention, in the solid-state imaging device according to the third aspect, the predetermined shape is a concave lens shape having a predetermined curvature for diverging incident light into the gap.

  Thereby, since the incident light to the gap can be diverged, it is possible to prevent an increase in the amount of light received by the pixels adjacent to the phase difference detection pixels.

  According to a seventh aspect of the present invention, in the solid-state imaging device according to the sixth aspect, a plurality of the concave lens shapes are formed in one gap.

  Thereby, since the incident light to the gap can be diverged, it is possible to prevent an increase in the amount of light received by the pixels adjacent to the phase difference detection pixels.

  As described in claim 8, in the solid-state imaging device according to claim 3, the predetermined shape is a repeated shape of unevenness for diverging light incident on the gap.

  Thereby, since the incident light to the gap can be diverged, it is possible to prevent an increase in the amount of light received by the pixels adjacent to the phase difference detection pixels.

  According to a ninth aspect of the present invention, in the solid-state imaging device according to the eighth aspect of the present invention, the repeated shape of the unevenness is arranged along one direction.

  Thereby, since the incident light to the gap can be diverged, it is possible to prevent an increase in the amount of light received by the pixels adjacent to the phase difference detection pixels.

  According to a tenth aspect of the present invention, in the solid-state imaging device according to the eighth aspect, the concavo-convex repetitive shape is randomly formed.

  Thereby, since the incident light to the gap can be diverged, it is possible to prevent an increase in the amount of light received by the pixels adjacent to the phase difference detection pixels.

  In order to achieve the above object, in the imaging apparatus using the solid-state imaging device according to any one of claims 1 to 10, focusing is performed based on output signals of the second photoelectric conversion device and the third photoelectric conversion device. An automatic focusing means for moving the lens to the in-focus position is provided.

  As a result, it is possible to appropriately realize autofocus and provide an image free from color mixing and sensitivity unevenness.

  According to the present invention, it is possible to prevent an increase in the amount of light received by a pixel adjacent to a phase difference detection pixel, and thus it is possible to provide an image free from color mixing or sensitivity unevenness.

The figure which shows the conventional solid-state image sensor The figure which shows the solid-state image sensor of 1st Embodiment. The figure which shows the solid-state image sensor of 2nd Embodiment. The figure which shows the solid-state image sensor of 3rd Embodiment. The figure which shows the solid-state image sensor of 4th Embodiment. The figure which shows the electrical constitution of the digital camera using the solid-state image sensor which concerns on this invention

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

<Construction of a conventional solid-state imaging device>
FIG. 1A is a top view of a light receiving surface of a conventional solid-state imaging device 10, and FIG. 1B is a cross-sectional view taken along a broken line AA ′ in FIG.

  As shown in FIG. 1A, the solid-state imaging device 10 includes a large number of photoelectric conversion elements (photodiodes) PD formed in an array on the light receiving surface. Each photodiode PD is equally arranged in the row direction and the column direction, and is separated for each pixel by a pixel separation region (not shown) provided around the photodiode PD. In addition, a vertical transfer path (VCCD) (not shown) is arranged between the pixels, and the signal charge accumulated in each photodiode PD is transferred in the vertical direction through the vertical transfer path. These photodiodes PD are embedded in the semiconductor substrate.

  An insulating film and a color filter layer (not shown) are formed on the upstream side of the optical path of the photodiode PD. The color filter layer is composed of red (R), green (G), and blue (B) primary color filters arranged in a predetermined arrangement structure such as a Bayer arrangement. Or one color filter is arranged to correspond.

  Further, microlenses L1, L2, and L3 for forming a subject image corresponding to each photodiode PD are formed on the upstream side of the optical path of the color filter layer.

  The solid-state imaging device 10 has pixels for obtaining an automatic focus detection signal of a phase difference detection method in addition to normal pixels for forming an image.

  A normal pixel includes a first microlens L1 for causing a corresponding photodiode PD to receive light passing through the entire lens pupil of a photographing lens (not shown). The first microlens L1 is arranged so that the center thereof coincides with the center of the corresponding photodiode PD when viewed from the upper surface of the light receiving surface. Note that the first microlens L1 may be arranged by slightly scaling the arrangement pitch of the photodiodes PD from the center to the periphery of the light receiving surface of the solid-state imaging device 10.

  There are two types of pixels for detecting the phase difference, and one of the pixels is a first pixel for causing the corresponding photodiode PD to receive light passing through the right half when viewed from the upper surface of the light receiving surface of the lens pupil of the photographing lens (not shown). Two microlenses L2 are provided. The second microlens L2 is formed to have a smaller diameter than the first microlens L1, and is shifted from the corresponding photodiode PD to the right side when viewed from the upper surface of the light receiving surface.

  Further, the other pixel for phase difference detection includes a third microlens L3 for causing the corresponding photodiode PD to receive the light passing through the left half when viewed from the upper surface of the light receiving surface of the lens pupil of the photographing lens (not shown). ing. The third microlens L3 is formed to have the same size as the second microlens L2, and is shifted from the corresponding photodiode PD to the left when viewed from the upper surface of the light receiving surface.

  In this way, the output signal of the photodiode PD that receives the light passing through the right half of the lens pupil via the second microlens L2, and the light passing through the right half of the lens pupil via the third microlens L3. By detecting the phase difference from the output signal of the photodiode PD that receives light, it is possible to calculate the defocus amount of the focus lens and realize autofocus.

  Here, the second microlens L2 and the third microlens L3 are arranged such that the diameters of the second microlens L2 and the third microlens L3 are smaller than those of the first microlens L1, and the positions thereof are shifted. A gap SP is formed around each of L2 and the third microlens L3.

  As shown in FIG. 1, the first microlens L1 adjacent to the gap SP has an adjacent microlens that serves as a stopper against the spread in the diameter direction when the microlens L1 is formed. Therefore, the diameter is formed larger than the shape to be originally formed shown by the dotted line.

  As a result, the light a shown in FIG. 1B that should not be collected on the photodiode PD is collected on the photodiode PD. That is, the light that is incident on the portion outside the shape where the microlens is supposed to be formed, and the light that is incident on the portion where the microlens is formed large should not be condensed on the photodiode PD. However, in practice, the light is condensed on the photodiode PD, and as a result, the amount of light received by the adjacent pixels in the gap SP increases. In addition, when the color of the color filter arranged in the gap SP and the color filter of the adjacent pixel are different, color mixing occurs in the adjacent pixel.

  Furthermore, the light b incident on the gap SP shown in FIG. 1B is also incident on the photodiode PD. As a result, the amount of light received by adjacent pixels in the gap SP increases.

  As described above, when the amount of light received by adjacent pixels increases, color mixture and sensitivity unevenness occur in the captured image.

  The present applicant has found that these problems occur, and has further found that the above problems can be solved by the following means.

<First Embodiment>
FIG. 2 is a cross-sectional view of the solid-state imaging device 11 of the first embodiment. As shown in the figure, in the solid-state imaging device 11 of the present embodiment, dummy microlenses 21 are formed in a gap portion formed around the second microlens L2 and the third microlens L3.

  Since the dummy microlens 21 serves as a stopper against the spread in the diameter direction when the microlens L1 is formed, the microlens L1 is formed in a shape to be originally formed.

  Therefore, the light a incident on the portion outside the shape to be originally formed is not condensed on the photodiode PD, and as a result, the amount of light received by the adjacent pixels of the dummy microlens 21 increases. Can be prevented.

<Second Embodiment>
FIG. 3A is a cross-sectional view of the solid-state imaging device 12 according to the second embodiment, and FIG. 3B is a perspective view of the light receiving surface thereof. As shown in the figure, the solid-state imaging device 12 has a convex lens 22 formed in a gap portion formed around the second microlens L2 and the third microlens L3.

  Since the convex lens 22 serves as a stopper against the spread in the diameter direction when the microlens L1 is formed, the microlens L1 is formed in a shape to be originally formed.

  Therefore, the light a incident on the portion outside the shape to be originally formed is not condensed on the photodiode PD, and as a result, the problem of an increase in the amount of light received by the adjacent pixels of the convex lens 22 is prevented. be able to.

  Further, the light b incident on the convex lens 22 is condensed by the convex lens 22 onto a portion where the photodiode PD is not formed.

  Therefore, the light b is not incident on the photodiode PD adjacent to the convex lens 22, and the problem that the amount of light received by the adjacent pixels increases can be prevented.

  In addition, you may form a convex lens like the shape shown to 22a of FIG.3 (c). In such a configuration, it is impossible to prevent the microlens L1 from spreading when formed, but the light incident on the convex lens 22a can be condensed on a portion where the photodiode PD is not formed.

  Further, as shown in FIG. 3D, a plurality of convex lenses 22b may be formed. Even when the convex lens 22b is formed in this way, the light incident on the convex lens 22b can be condensed on a portion where the photodiode PD is not formed.

<Third Embodiment>
FIG. 4A is a cross-sectional view of the solid-state imaging device 13 of the third embodiment, and FIG. 4B is a perspective view of the light receiving surface thereof. As shown in the figure, the solid-state imaging device 13 has a concave lens 23 formed in a gap portion formed around the second microlens L2 and the third microlens L3.

  Since the light b incident on the concave lens 23 is diffused by the concave lens 23, the amount of light incident on the adjacent photodiode PD is reduced as compared with the case where the light b is incident on the gap SP shown in FIG. Is done. Therefore, it is possible to reduce the problem that the amount of light received by adjacent pixels increases.

  In addition, you may form a concave lens like the shape shown to 23a of FIG.4 (c). Even when the concave lens 23a is formed in this way, the light incident on the concave lens 23a is diverged by each concave lens 23, so that the amount of light incident on the adjacent photodiode PD is reduced.

<Fourth Embodiment>
FIG. 5A is a cross-sectional view of the solid-state imaging device 14 of the fourth embodiment, and FIG. 5B is a perspective view of the light receiving surface thereof. As shown in the figure, in the solid-state imaging device 14, a diffusion plate shape 24 is formed in a gap portion formed around the second microlens L2 and the third microlens L3.

  The diffuser plate shape 24 has an uneven shape along the short side direction of the gap portion, and the light b incident on the diffuser plate shape 24 is diverged by the diffuser plate shape 24, so that the adjacent photodiode PD The amount of light incident on is reduced. Therefore, it is possible to reduce the problem that the amount of light received by adjacent pixels increases.

  Note that the diffuser plate shape may be formed in an uneven shape along the long side direction of the gap portion, or a large number of uneven shapes may be randomly formed such as the shape shown by 24a in FIG. . Even when the diffusing plate 24a is formed in this way, the light incident on the diffusing plate 24a is diverged by the uneven shapes, so that the amount of light incident on the photodiode PD is reduced.

<Configuration of digital camera>
Next, a digital camera 100 will be described as a specific application example of an imaging apparatus using the above-described solid-state imaging device.

  FIG. 6 is a diagram showing an electrical configuration of the digital camera 100 according to an embodiment of the present invention. As shown in the figure, the digital camera 100 includes an imaging unit 51, a signal processing unit 54, an image input controller 55, a CPU 56, an operation unit 57, a bus 58, a memory control unit 59, a memory 60, a digital signal processing unit 61, and a compression. The expansion processing unit 62, the recording medium control unit 63, the recording medium 64, the display control unit 65, the display unit 66, the phase difference detection unit 67, the defocus amount calculation unit 68, and the lens driving unit 69 are configured.

  Each unit operates under the control of the CPU 56, and the CPU 56 controls each unit of the digital camera 100 by executing a predetermined control program based on an input from the operation unit 57. The operation unit 57 is an operation member for a user to input various commands to the digital camera 100, and includes a shutter button, a mode switch, and the like.

  The imaging unit 51 includes a photographic lens 52 and a solid-state imaging device 11. Here, the solid-state imaging device 11 is used, but any of the solid-state imaging devices 12, 12a, 12b, 13, 13a, 14, and 14a described above may be used.

  The photographing lens 52 includes a zoom lens and a focus lens, and is driven by a lens driving unit to perform zooming and focusing.

  The solid-state image sensor 11 has pixels for obtaining a phase difference detection type auto focus detection signal in addition to normal pixels for forming an image. The phase difference detection pixels are arranged at predetermined intervals in a predetermined range of the light receiving surface.

  The electric signal accumulated in each photodiode PD of the solid-state image sensor 11 is read out to the vertical transfer path. The vertical transfer path transfers this signal to the horizontal transfer path line by line in synchronization with the clock supplied from the timing generator. Further, the horizontal transfer path outputs the signal for one line transferred from the vertical transfer path to the signal processing unit 54 in synchronization with the clock supplied from the timing generator.

  An image signal output from the imaging unit 51 is input to the signal processing unit 54. The signal processing unit 54 performs analog amplification of the image signal with a predetermined gain corresponding to the set photographing sensitivity (ISO sensitivity) and a correlated double sampling circuit for removing reset noise included in the image signal. And a variable gain amplifier circuit for removing the reset noise of the image signal output from the solid-state imaging device 11 and amplifying the image signal. Further, the signal processing unit 54 includes an A / D converter, and the analog image signal subjected to the required signal processing is converted into a digital image signal having a predetermined bit gradation width in the A / D conversion unit. Converted. This image signal is so-called RAW data, and has a gradation value indicating the density of R, G, and B for each pixel.

  The RAW data output from the signal processing unit 54 is input to the image input controller 55. The image input controller 55 has a built-in line buffer having a predetermined capacity, and stores the image signal output from the signal processing unit 54. These image signals are stored in the memory 60 via the bus 58 and the memory control unit 59.

  The digital signal processing unit 61 includes an AWB gain calculation unit, an AWB processing unit, a light source estimation unit, an RGB / YC conversion unit, a contrast correction unit, a saturation correction unit, and the like, and is stored in the memory 60. , G, B RAW data is read out, and a white balance is adjusted by applying a digital gain corresponding to the light source type to these, and a gamma (gradation characteristic) process and a sharpness process are performed to obtain R, G, B signals. Then, the luminance signal Y and chroma signals Cr and Cb (YC signal) are generated by further YC signal processing, and the YC signal is stored in the memory 60 again. The contrast correction unit and the saturation correction unit correct the contrast and saturation of the image as necessary.

  The compression / decompression processing unit 62 performs compression processing of a predetermined format (for example, JPEG) on the input YC signal in accordance with a compression command from the CPU 56 to generate compressed image data. Further, in accordance with a decompression command from the CPU 56, the input compressed image data is subjected to decompression processing in a predetermined format to generate uncompressed image data.

  The recording medium control unit 63 controls reading / writing of data with respect to the recording medium 64 in accordance with an instruction from the CPU 56. The recording medium 64 may be detachable from the camera body such as a memory card, or may be built in the camera body. In the case of detachable, a card slot is provided in the camera body, and the card slot is used by being loaded.

  The display control unit 65 controls display on the display unit 66 in accordance with a command from the CPU 16. The display unit 66 is a liquid crystal monitor capable of displaying an image based on the image signal captured by the imaging unit 51. The captured image recorded on the recording medium 64 is decompressed by the compression / decompression processing unit 62. It can also be displayed later.

  The phase difference detection unit 67 stores signals of pixels (phase difference detection pixels) corresponding to the second microlens L2 and the third microlens L3 among the output signals of the photodiodes of the solid-state imaging device 11. 60, and the phase difference of each signal is calculated.

  The defocus amount calculation unit 68 calculates the defocus amount (movement amount) of the focus lens of the photographing lens 52 based on the calculation result of the phase difference detection unit 67.

  Further, the lens driving unit 69 drives the focus lens of the photographing lens 52 based on the calculation result of the defocus amount calculating unit 68 to focus the photographing lens 52.

  With the configuration as described above, it is possible to realize an imaging apparatus using the solid-state imaging device shown in the first to fourth embodiments. Therefore, it is possible to appropriately realize autofocus and provide an image free from color mixing and sensitivity unevenness.

  DESCRIPTION OF SYMBOLS 10, 11, 12, 13, 14 ... Solid-state image sensor, 21 ... Dummy microlens, 22 ... Convex lens, 23 ... Concave lens, 24 ... Diffuser shape, 52 ... Shooting lens, 67 ... Phase difference detection part, 68 ... Defocus Quantity calculation unit, 69 ... lens driving unit, L1 ... first microlens, L2 ... second microlens, L3 ... third microlens, PD ... photodiode, SP ... gap

Claims (11)

A photoelectric conversion element that converts received light into a signal charge, and a plurality of photoelectric conversion elements that are two-dimensionally arranged in the row direction and the column direction at equal intervals, and upstream of the corresponding optical path of the corresponding photoelectric conversion element In a solid-state imaging device comprising: a plurality of microlenses arranged; and a plurality of microlenses for condensing light received through a photographing lens on corresponding photoelectric conversion elements,
The photoelectric conversion element is
A first photoelectric conversion element for obtaining an image signal for forming a captured image;
A second photoelectric conversion element and a third photoelectric conversion element for obtaining at least a phase difference detection type auto focus detection signal;
Including
The plurality of microlenses are:
A first microlens that causes a corresponding first photoelectric conversion element to receive light passing through the entire area of the lens pupil of the photographing lens, the first microlens being disposed at a predetermined position with respect to the corresponding photoelectric conversion element A microlens,
A second microlens that causes a corresponding second photoelectric conversion element to receive light passing through one of the regions obtained by dividing the lens pupil of the photographing lens by a predetermined center line, the first microlens A second microlens formed smaller than the predetermined photoelectric conversion element and shifted from the predetermined position in the first direction;
A third microlens that causes the corresponding third photoelectric conversion element to receive light passing through the other region of the divided regions, and is formed smaller than the first microlens and corresponding photoelectric conversion A third microlens arranged to be shifted from the predetermined position with respect to the element in a direction opposite to the first direction;
Including
The amount of light received by the first photoelectric conversion element due to light incident on the gap in the gap between the plurality of microlenses and formed around the second microlens or the third microlens. A solid-state imaging device characterized by forming a predetermined shape for reducing an increase.   The solid-state imaging device according to claim 1, wherein the predetermined shape is a fourth microlens shape for suppressing the spread of the first microlens.   2. The solid-state imaging device according to claim 1, wherein the predetermined shape is a shape for preventing light incident on the gap from being condensed on an adjacent photoelectric conversion device.   The solid-state imaging device according to claim 3, wherein the predetermined shape is a convex lens shape having a predetermined curvature for condensing incident light to the gap at a position other than the photoelectric conversion element.   The solid-state imaging device according to claim 4, wherein a plurality of the convex lens shapes are formed in one gap.   The solid-state imaging device according to claim 3, wherein the predetermined shape is a concave lens shape having a predetermined curvature for diverging light incident on the gap.   The solid-state imaging device according to claim 6, wherein a plurality of the concave lens shapes are formed in one gap.   The solid-state imaging device according to claim 3, wherein the predetermined shape is a repetitive shape of unevenness for diverging incident light to the gap.   The solid-state imaging device according to claim 8, wherein the concave and convex repeated shapes are arranged along one direction.   The solid-state image pickup device according to claim 8, wherein the uneven shape is formed at random. In the imaging device using the solid-state image sensor according to any one of claims 1 to 10,
An image pickup apparatus comprising: an automatic focusing unit that moves a focus lens to a focusing position based on output signals of the second photoelectric conversion element and the third photoelectric conversion element.

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