JP4839990B2 - 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 apparatus using the same.

  In recent years, imaging devices such as video cameras and electronic cameras have been widely spread. For these cameras, a CCD type solid-state imaging device (the following Patent Document 1) and an amplification type solid-state imaging device are used. In these solid-state imaging devices, a plurality of pixels that output imaging signals for forming an image signal indicating a subject image are arranged in a matrix. Each pixel has a photoelectric conversion unit that photoelectrically converts incident light and obtains a charge to be the imaging signal. In the amplification type solid-state imaging device, the signal charge obtained by the photoelectric conversion unit is guided to the amplification unit provided in the pixel, and the signal amplified by the amplification unit is output from the pixel. As the amplification type solid-state imaging device, for example, a solid-state imaging device using a junction field effect transistor (JFET) in an amplification unit, a solid-state imaging device using a MOS transistor in an amplification unit (Patent Documents 2 and 3 below), etc. There is.

  A microlens is disposed on-chip on the light incident side of the photoelectric conversion unit. Light incident on the pixel portion other than the photoelectric conversion portion does not contribute to the optical signal and is wasted. The microlens is disposed in each pixel in order to collect the light thus wasted on the photoelectric conversion unit and increase the amount of light. In order to obtain a color image, a color filter is disposed on the photoelectric conversion unit. As a combination of color filters, a system using R, G, and B or a complementary color system (for example, a system using magenta, green, cyan, and yellow) is used. As the arrangement of the color filters, a Bayer arrangement, a stripe arrangement, and the like are well known.

  By the way, in an imaging apparatus such as a camera, it is necessary to detect the focus adjustment state of the photographing lens in order to realize automatic focus adjustment. Conventionally, a focus detection element has been provided separately from the solid-state imaging element. However, in that case, the cost increases or the size of the apparatus increases by the amount of the focus detection element and the focus detection optical system that guides light to the focus detection element.

  Therefore, in recent years, a so-called pupil division phase difference method (sometimes called a pupil division method or a phase difference method) is adopted as a focus detection method, and solid-state imaging configured to be used as a focus detection element. Elements have been proposed (for example, Patent Documents 1 to 3 below). The pupil division phase difference method detects the defocus amount of the photographing lens by forming a pair of divided images by dividing the light beam passing through the photographing lens into pupils and detecting the pattern shift (phase shift amount). is there.

  In addition to a plurality of imaging pixels, the solid-state imaging device disclosed in Patent Document 1 includes a plurality of first focus detection pixels (pixels denoted by reference sign “S1” in Patent Document 1) and a plurality of first imaging pixels. 2 focus detection pixels (pixels to which “S2” is attached in Patent Document 1). Each of these pixels has only one photoelectric conversion unit. As shown in FIG. 3 and FIG. 4 of Patent Document 1, each pixel includes a microlens provided on the photoelectric conversion unit in a one-to-one relationship with the pixel. A light shielding film is provided near the focal plane of the microlens between the microlens and the photoelectric conversion unit, and an opening is provided in the light shielding film for each of the first and second focus detection pixels. Yes. In the first focus detection pixel, the opening of the light shielding film is arranged so as to be biased with respect to the optical center of the microlens. In the second focus detection pixel, the opening of the light shielding film is located at the optical center of the microlens. On the other hand, the first focus detection pixels are arranged so as to be biased in the opposite direction. Thus, the first focus detection pixel selectively receives and photoelectrically converts a light beam from a partial region of the exit pupil of the photographing lens and decentered in a predetermined direction from the center of the exit pupil. It will be. The second focus detection pixel selectively receives and photoelectrically converts a light beam from a partial region of the exit pupil of the photographing lens that is decentered in the opposite direction from the center of the exit pupil. become. In the solid-state imaging device disclosed in Patent Document 1, a color filter is provided in the imaging pixel. However, as illustrated in FIGS. 3 and 4 of Patent Document 1, the first and second pixels are used. These focus detection pixels are not provided with a color filter.

  The first and second focus detection pixels are used only for focus detection. When an image is captured after the photographing lens is focused, the first and second focus detection pixels in the image signal are used. For example, a signal obtained by performing interpolation processing from signals of the surrounding imaging pixels is used as the pixel signal at the position.

  Further, in the solid-state imaging device disclosed in FIG. 12 of Patent Document 2, each pixel of all the pixels is divided into two photoelectric conversion units and pixels on the two divided photoelectric conversion units. A microlens provided in a one-to-one relationship is provided. The two-divided photoelectric conversion unit is disposed at a position that is substantially image-formed (ie, substantially conjugate) with the exit pupil of the photographing lens by the microlens. From the relationship described above, in each pixel, one part of the photoelectric conversion unit divided into two is a light beam from a region that is a part of the exit pupil of the photographing lens and decentered in a predetermined direction from the center of the exit pupil. Is selectively received and photoelectrically converted. Further, in each pixel, the other part of the photoelectric conversion unit divided into two is selectively a light beam from a region that is a part of the exit pupil of the photographing lens and decentered in the opposite direction from the center of the exit pupil. Light is received and photoelectrically converted. Note that in the solid-state imaging device disclosed in FIG. 12 of Patent Document 2, all pixels are provided with color filters.

  In the solid-state imaging device disclosed in FIG. 12 of Patent Document 2, at the time of focus detection, the signal of one part of the photoelectric conversion unit divided into two and the signal of the other part of each pixel are transferred to the floating diffusion at different timings. Are read out individually. Then, according to the principle of the pupil division phase difference method, the focus adjustment state of the photographing lens is detected based on these signals. On the other hand, when an image is taken after focusing of the photographic lens, the signals from both parts of the photoelectric conversion unit divided into two for each pixel are transferred to the same floating diffusion at the same timing, and both signals are transferred into the pixel. Are added and read.

  As described above, in the solid-state imaging device disclosed in FIG. 12 of Patent Document 2, each pixel of all the pixels is divided into two photoelectric conversion units (therefore, two photoelectric conversions arranged in the plane direction of the substrate). Part) and also serves as both an imaging pixel and a focus detection pixel.

  The solid-state image sensor disclosed in Patent Document 3 is configured in the same manner as the solid-state image sensor disclosed in FIG.

  Further, in the solid-state imaging device disclosed in FIGS. 1 to 10 of Patent Document 2, only some of the pixels are divided into two photoelectric conversion units, while the remaining pixels are divided into photoelectric conversion units. No pixel (that is, the pixel has only one photoelectric conversion unit), and a color filter is formed in a pixel in which the photoelectric conversion unit is not divided into two, while a pixel in which the photoelectric conversion unit is divided in two Does not form a color filter. In this solid-state imaging device, the pixel in which the photoelectric conversion unit is divided into two is used only to obtain a focus detection signal, and the pixel in which the photoelectric conversion unit is not divided into two is used only to obtain an imaging signal. Yes.

  By the way, when obtaining a color image signal, a general solid-state imaging device is configured so that each pixel obtains only one color imaging signal, and each color pixel is arranged in a Bayer array or the like (Patent Documents 1 to 3). 3).

In contrast, in Patent Documents 4 and 5, the light absorption coefficient of silicon and other semiconductors is highly wavelength-dependent, and by utilizing the characteristic that the depth to reach the inside of the semiconductor differs depending on the wavelength, A solid-state imaging device configured to output imaging signals for each color (specifically, R, G, and B imaging signals) from one pixel independently of each other is disclosed. In this solid-state imaging device, an R photoelectric conversion unit that mainly photoelectrically converts an R component of incident light, a G photoelectric conversion unit that mainly photoelectrically converts a G component of incident light, and a B component of incident light in one pixel. A photoelectric conversion unit for B that mainly performs photoelectric conversion is provided, and these three photoelectric conversion units are arranged so as to overlap each other when viewed from the incident direction of incident light. Patent Documents 4 and 5 do not disclose or suggest a configuration for obtaining a focus detection signal, and the solid-state imaging device disclosed in Patent Documents 4 and 5 can obtain only an imaging signal. The focus detection signal cannot be obtained.
JP 2000-156823 A JP 2003-244712 A JP 2002-314062 A JP-T-2002-513145 US Patent Application Publication No. 2005/0194653

  However, in the solid-state imaging device disclosed in Patent Document 1 and the solid-state imaging device disclosed in FIGS. 1 to 10 of Patent Document 2, the focus detection pixels are used only for focus detection and are used during image capturing. Since it cannot be used, the same state as a pixel defect is caused by the number of focus detection pixels, and the image quality of the captured image is inevitably deteriorated although interpolation processing is performed. Further, since a circuit for performing interpolation processing is required, the cost increases and the size increases.

  On the other hand, in the solid-state imaging device disclosed in FIG. 12 of Patent Document 2 and the solid-state imaging device disclosed in Patent Document 3, a two-divided photoelectric sensor that serves both for imaging and for focus detection is used during imaging. For pixels having a conversion unit, signals from both parts of the two-divided photoelectric conversion unit are added and read in the pixel, so that deterioration of image quality due to a state similar to a pixel defect can be avoided.

  However, in these solid-state image sensors, a dead zone where the incident light cannot be photoelectrically converted between the two parts of the two-part photoelectric conversion unit of each pixel, and the light incident between the two parts is completely used for forming an imaging signal. Therefore, the utilization efficiency of incident light is lowered. Therefore, when the signal for imaging is obtained, even if the signals of the two parts divided into two parts are added, the signal for imaging becomes smaller than in the case of obtaining the signal for imaging with one undivided photoelectric conversion unit. End up. That is, in the case of obtaining an imaging signal, the utilization efficiency of incident light is lowered, and the sensitivity of the imaging signal is reduced.

  The present invention has been made in view of such circumstances, and on the premise that it also has a function as a focus detection element, it is possible to avoid degradation of image quality due to the same state as a pixel defect, and An object of the present invention is to provide a solid-state imaging device capable of increasing the efficiency of use of incident light with respect to an imaging signal, and an imaging apparatus using the same.

  In order to solve the above-described problem, the solid-state imaging device according to the first aspect of the present invention is a solid-state imaging device that photoelectrically converts a subject image formed by an optical system, and is arranged in a two-dimensional manner, each of which is the subject. The image forming apparatus includes a plurality of pixels that output imaging signals for forming an image signal indicating an image. Each one of the plurality of pixels has an imaging photoelectric conversion unit that mainly photoelectrically converts a predetermined wavelength component of incident light to obtain charges to be the imaging signal. At least some of the plurality of pixels can output a plurality of focus detection signals for detecting a focus adjustment state of the optical system independently of each other in addition to the imaging signal. Composed. In addition to the imaging photoelectric conversion unit of the pixel, each of the at least some of the pixels has at least a part of the imaging photoelectric of the pixel when viewed from the incident direction of the incident light. A plurality of focus detection photoelectric conversion units arranged so as to overlap with the conversion unit, the wavelength component being substantially different from the predetermined wavelength component of the incident light that is photoelectrically converted by the imaging photoelectric conversion unit of the pixel Are mainly photoelectrically converted, and a plurality of focus detection photoelectric conversion units are provided to respectively obtain charges to be converted into the plurality of focus detection signals. The plurality of focus detection photoelectric conversion units of each one of the at least some pixels respectively select light beams from the exit pupil regions that are decentered in different directions from the center of the exit pupil of the optical system. Light is received and photoelectrically converted.

  The solid-state imaging device according to a second aspect of the present invention is the solid-state imaging device according to the first aspect, wherein the incident light that is mainly photoelectrically converted by the imaging photoelectric conversion unit of the pixel for each one of the at least some pixels. The predetermined wavelength component and the wavelength component of the incident light that is mainly photoelectrically converted by the focus detection photoelectric conversion units of the pixel are wavelength components in the visible range.

  In the solid-state imaging device according to the third aspect of the present invention, in the first or second aspect, the number of the plurality of focus detection photoelectric conversion units in each one of the at least some pixels is two. And one of the plurality of focus detection photoelectric conversion units of each of the at least some pixels is decentered in a predetermined direction from the center of the exit pupil of the optical system. The light beam from the first region of the exit pupil is selectively received and photoelectrically converted, and the other one of the plurality of focus detection photoelectric conversion units of each of the at least some pixels is used for imaging. The photoelectric conversion unit selectively receives and photoelectrically converts a light beam from the second region of the exit pupil that is decentered from the center of the exit pupil of the optical system in a direction opposite to the predetermined direction.

  The solid-state imaging device according to the fourth aspect of the present invention is the solid-state imaging device according to any one of the first to third aspects, wherein the imaging photoelectric conversion unit of at least one of the at least some pixels is the first. Each focus detection photoelectric conversion of the at least one pixel has a second conductivity type imaging charge accumulation layer that is disposed in the first conductivity type semiconductor layer and accumulates the charge to be the imaging signal. The portion of the first semiconductor layer overlaps with the imaging charge storage layer of the pixel through at least part of the first semiconductor layer when viewed from the incident direction of the incident light. It has a second conductivity type focus detection charge storage layer for storing the charge to be arranged and to become one focus detection signal among the plurality of focus detection signals of the pixel.

  A solid-state imaging device according to a fifth aspect of the present invention is the solid-state imaging device according to the fourth aspect, wherein the first conductivity type layer having an impurity concentration higher than that of the first semiconductor layer in the at least one pixel. The first semiconductor layer is disposed between the imaging charge storage layer and each focus detection charge storage layer.

  The solid-state imaging device according to a sixth aspect of the present invention is the solid-state imaging device according to any one of the first to fifth aspects, wherein at least one of the at least some pixels is used for detecting the plurality of focus points of the pixel. The photoelectric conversion unit photoelectrically converts substantially the same wavelength component of the incident light.

  The solid-state imaging device according to a seventh aspect of the present invention is the solid-state imaging device according to any one of the first to sixth aspects, wherein the imaging photoelectric conversion unit of the pixel is mainly the at least one pixel. The predetermined wavelength component of the incident light that undergoes photoelectric conversion is a wavelength component that is shorter than the wavelength component of the incident light that is mainly photoelectrically converted by each focus detection photoelectric conversion unit of the pixel.

  The solid-state imaging device according to an eighth aspect of the present invention is the solid-state imaging device according to any one of the first to sixth aspects, wherein the imaging photoelectric conversion unit of the pixel is mainly the at least one pixel. The predetermined wavelength component of the incident light that undergoes photoelectric conversion is a wavelength component that is longer than the wavelength component of the incident light that is primarily photoelectrically converted by each focus detection photoelectric conversion unit of the pixel.

  The solid-state imaging device according to a ninth aspect of the present invention is the solid-state imaging device according to any one of the first to eighth aspects, wherein each one of the at least some pixels is provided on a one-to-one basis with respect to the pixel. A microlens that guides incident light to the imaging photoelectric conversion unit and the plurality of focus detection photoelectric conversion units of the pixel is provided.

  A solid-state imaging device according to a tenth aspect of the present invention is a solid-state imaging device that photoelectrically converts a subject image formed by an optical system, and is two-dimensionally arranged to form an image signal that indicates the subject image. A plurality of pixels that output imaging signals for the purpose. Each one of the plurality of pixels has an imaging photoelectric conversion unit that mainly photoelectrically converts a predetermined wavelength component of incident light to obtain charges to be the imaging signal. At least some of the plurality of pixels are configured to independently output a focus detection signal for detecting a focus adjustment state of the optical system in addition to the imaging signal. . In addition to the imaging photoelectric conversion unit of the pixel, each of the at least some of the pixels includes at least a part of the imaging photoelectric conversion unit of the pixel when viewed from the incident direction of the incident light. A photoelectric conversion unit for focus detection arranged so as to overlap with the photoelectric conversion unit, which mainly converts a wavelength component substantially different from the predetermined wavelength component of the incident light that is photoelectrically converted by the imaging photoelectric conversion unit of the pixel. And a focus detection photoelectric conversion unit for obtaining a charge to be the focus detection signal. The focus detection photoelectric conversion unit of some of the at least some pixels selects a light beam from the first region of the exit pupil that is decentered in a predetermined direction from the center of the exit pupil of the optical system. Light is received and photoelectrically converted. The focus detection photoelectric conversion unit of another part of the at least some of the pixels includes a first part of the exit pupil that is decentered in a direction opposite to the predetermined direction from the center of the exit pupil of the optical system. The light beam from the region 2 is selectively received and photoelectrically converted.

  The solid-state imaging device according to an eleventh aspect of the present invention is the solid-state imaging device according to the tenth aspect, wherein the incident light that the imaging photoelectric conversion unit of the pixel mainly photoelectrically converts with respect to each one of the at least some pixels. The predetermined wavelength component and the wavelength component of the incident light which is mainly photoelectrically converted by the focus detection photoelectric conversion unit of the pixel are wavelength components in the visible range.

  A solid-state imaging device according to a twelfth aspect of the present invention is the tenth or eleventh aspect, wherein the imaging photoelectric conversion unit of at least one of the at least some pixels is of the first conductivity type. An imaging charge storage layer of a second conductivity type that is disposed in the first semiconductor layer and accumulates the charge to be the imaging signal, and the focus detection photoelectric conversion unit of the at least one pixel includes: The pixel disposed in the first semiconductor layer so that at least a part thereof overlaps the charge storage layer for imaging of the pixel through a part of the first semiconductor layer when viewed from the incident direction of the incident light. The second-conductivity-type focus detection charge storage layer stores the charge to be the focus detection signal.

  The solid-state imaging device according to a thirteenth aspect of the present invention is the solid-state imaging device according to the twelfth aspect, wherein the first conductivity type layer having an impurity concentration higher than that of the first semiconductor layer in the at least one pixel. The first semiconductor layer is disposed between the imaging charge storage layer and the focus detection charge storage layer.

  In any one of the tenth to thirteenth aspects, with respect to at least one of the at least some of the pixels, the predetermined wavelength component of the incident light that is mainly photoelectrically converted by the imaging photoelectric conversion unit of the pixel is: The focus detection photoelectric conversion unit of the pixel may have a wavelength component shorter than the wavelength component of the incident light that is mainly photoelectrically converted.

  In any one of the tenth to thirteenth aspects, with respect to at least one of the at least some of the pixels, the predetermined wavelength component of the incident light that is mainly photoelectrically converted by the imaging photoelectric conversion unit of the pixel is: The focus detection photoelectric conversion unit of the pixel may have a wavelength component longer than the wavelength component of the incident light that is mainly photoelectrically converted.

  In any one of the tenth to thirteenth aspects, each of the at least some of the pixels is provided on a one-to-one basis with respect to the pixel, and the imaging photoelectric conversion unit and the focus detection of the pixel You may have the microlens which guides incident light to the photoelectric conversion part for optical.

  According to a fourteenth aspect of the present invention, in any one of the first to thirteenth aspects, the plurality of pixels are divided into a plurality of groups, and the imaging photoelectric conversion unit of the pixels of the same group The predetermined wavelength components of the incident light that are mainly photoelectrically converted are substantially the same as each other, and the predetermined wavelength components of the incident light that are mainly photoelectrically converted by the imaging photoelectric conversion units of the pixels of different groups are: They are substantially different from each other.

  The solid-state imaging device according to a fifteenth aspect of the present invention is the solid-state image sensor according to the fourteenth aspect, wherein the at least some pixels do not have a color filter.

  The solid-state imaging device according to a sixteenth aspect of the present invention is the solid-state imaging device according to the fourteenth or fifteenth aspect, wherein the plurality of pixels include pixels other than the at least some pixels, and the pixels other than the at least some pixels. The pixel has a color filter.

  An imaging apparatus according to a seventeenth aspect of the present invention is based on the solid-state imaging device according to any one of the first to sixteenth aspects and the focus detection signal from the at least some pixels. A detection processing unit for outputting a detection signal indicating the focus adjustment state is provided.

  In the seventeenth aspect, an adjustment unit may be provided that adjusts the focus of the optical system based on the detection signal from the detection processing unit.

  According to the present invention, it is possible to avoid deterioration in image quality due to a state similar to a pixel defect, on the premise that it also has a function as a focus detection element, and the use efficiency of incident light with respect to an imaging signal It is possible to provide a solid-state imaging device capable of enhancing the image quality and an imaging apparatus using the same.

  Hereinafter, a solid-state imaging device and an imaging device using the same according to the present invention will be described with reference to the drawings.

  [First Embodiment]

  FIG. 1 is a schematic block diagram showing an electronic camera 1 as an imaging device according to the first embodiment of the present invention. The electronic camera 1 is equipped with a photographing lens 2 as an optical system for forming a subject image. The photographing lens 2 is driven by a lens control unit 2a for focus and diaphragm. In the image space of the photographic lens 2, an imaging surface of a solid-state imaging device 3 that photoelectrically converts a subject image formed by the photographic lens 2 is disposed.

  The solid-state imaging device 3 is driven by a command from the imaging control unit 4 and outputs a signal. The signal output from the solid-state imaging device 3 is either an imaging signal for forming an image signal indicating a subject image or a focus detection signal for detecting the focus adjustment state of the photographing lens 2. In any case, the signal is processed through the signal processing unit 5 and the A / D conversion unit 6 and then temporarily stored in the memory 7. The memory 7 is connected to the bus 8. The bus 8 is also connected with a lens control unit 2a, an imaging control unit 4, a microprocessor 9, a focus calculation unit (detection processing unit) 10, a recording unit 11, an image compression unit 12, an image processing unit 13, and the like. The microprocessor 9 is connected to an operation unit 9a such as a release button. A recording medium 11a is detachably attached to the recording unit 11 described above. The operation of the electronic camera 1 will be described later.

  Although not shown, an optical low-pass filter to which an IR cut coat is applied is disposed between the solid-state imaging device 3 and the photographing lens 2. As a result, light having a wavelength band of about 700 nm or more is cut to prevent moire.

  FIG. 2 is a circuit diagram showing a schematic configuration of the solid-state imaging device 3 in FIG. The solid-state imaging device 3 includes a plurality of pixels 20 arranged in a matrix and a peripheral circuit for outputting a signal from the pixels 20. An imaging region in which the pixels 20 are arranged in a matrix is indicated by reference numeral 31. In FIG. 2, the number of pixels indicates 16 pixels 20 of 4 rows horizontally and 4 rows vertically. However, in the present embodiment, the number of pixels is much larger than that. However, in the present invention, the number of pixels is not particularly limited. In the present invention, the solid-state imaging device 3 has four types of pixels 20R, 20G, 20B1, and 20B2 to be described later as pixels, but in FIG. Show. The specific circuit configuration and structure will be described later. These pixels 20 output imaging signals or focus detection signals in accordance with peripheral circuit drive signals.

  The peripheral circuit includes a vertical scanning circuit 21, a horizontal scanning circuit 22, driving signal lines 23 and 24 connected thereto, a vertical signal line 25 for receiving a signal from the pixel 20, and a constant current source connected to the vertical signal line 25. 26, a correlated double sampling circuit (CDS circuit) 27, a horizontal signal line 28 for receiving a signal output from the CDS circuit 27, an output amplifier 29, and the like.

  The vertical scanning circuit 21 and the horizontal scanning circuit 22 output drive signals based on a command from the imaging control unit 4 of the electronic camera 1. Each pixel 20 is driven by receiving a drive signal output from the vertical scanning circuit 21 from a predetermined drive signal line 23, and outputs an imaging signal or a focus detection signal to the vertical signal line 25. There are a plurality of drive signals output from the vertical scanning circuit 21, and accordingly, a plurality of drive wirings 23. These will be described later.

  The signal output from the pixel 20 is subjected to predetermined noise removal by the CDS circuit 27. Then, a signal is output to the outside through the horizontal signal line 28 and the output amplifier 29 by the drive signal of the horizontal scanning circuit 22.

  FIG. 3 is a schematic plan view schematically showing the solid-state imaging device 3 (particularly, its imaging region 31) in FIG. In the present embodiment, as shown in FIG. 3, the imaging region 31 of the solid-state imaging device 3 includes two focus detection regions 32 and 33 having a cross shape disposed in the center and two disposed on both sides. Focus detection areas 34 and 35 and two focus detection areas 36 and 37 arranged above and below are provided. As shown in FIG. 3, an X axis and a Y axis that are orthogonal to each other are defined. The direction of the arrow in the X-axis direction is called the + X direction or + X side, and the opposite direction is called the -X direction or -X side, and the same applies to the Y-axis direction. A plane parallel to the XY plane coincides with the imaging surface (light receiving surface) of the solid-state imaging device 3. The arrangement in the X-axis direction is a row, and the arrangement in the Y-axis direction is a column. These points are the same for the drawings described later.

  FIG. 4 is a schematic enlarged view in which the vicinity of the focus detection region 35 in FIG. 3 is enlarged, and schematically shows the pixel arrangement. FIG. 5 is a schematic enlarged view in which the vicinity of the focus detection area 36 in FIG. 3 is enlarged, and schematically shows the pixel arrangement. As described above, the solid-state imaging device 3 includes the four types of pixels 20R, 20G, 20B1, and 20B2 as the pixels 20. 4 and 5, the pixel 20 </ b> R is denoted by the symbol “R”, the pixel 20 </ b> G is denoted by the symbol “G”, the pixel 20 </ b> B <b> 1 is denoted by the symbol “B <b> 1”, and the pixel 20 </ b> B <b> 2 is denoted by the symbol “B2”. Is attached. In FIG. 4 and FIG. 5, the symbol “B *” indicates any one of the pixel 20B1 and the pixel 20B2.

  The pixel 20R is configured to output a red imaging signal, the pixel 20G is configured to output a green imaging signal, and the pixels 20B1 and 20B2 are configured to output a blue imaging signal. Yes. In the following description, paying attention to the color of the imaging signal to be output, the pixel 20R may be called a red pixel, the pixel 20G may be called a green pixel, and the pixels 20B1 and 20B2 may be called blue pixels. Each color pixel forms one group. That is, in the present embodiment, the pixels 20 are divided into three groups: a group of red pixels, a group of blue pixels, and a group of green pixels.

  In the present embodiment, the pixels 20R and 20G are not configured to output a focus detection signal. On the other hand, the pixel 20B1 is configured to output two focus detection signals in addition to the blue imaging signal. The pixel 20B2 is also configured to output two focus detection signals in addition to the blue imaging signal. As will be described later, the pixel 20B1 and the pixel 20B2 are different depending on which region of the exit pupil of the photographing lens 2 the obtained focus detection signal is based on.

  In the present embodiment, as shown in FIGS. 4 and 5, the red pixel 20R, the green pixel 20G, and the blue pixels 20B1 and 20B2 are arranged according to the Bayer array. However, in the present invention, even when configured for color, it is not limited to the Bayer arrangement.

  As shown in FIG. 4, the focus detection area 35 extending in the Y-axis direction is a part of a column in the Y-axis direction in which green pixels 20G and blue pixels are alternately arranged. In the focus detection area 35, a blue pixel 20B1 is used as a blue pixel. The focus detection areas 33 and 34 extending in the Y-axis direction are the same as the focus detection area 35.

  As shown in FIG. 5, the focus detection area 36 extending in the X-axis direction is a part of a row in the X-axis direction in which green pixels 20G and blue pixels are alternately arranged. In the focus detection area 36, a blue pixel 20B2 is used as a blue pixel. The focus detection areas 36 and 37 extending in the X-axis direction are the same as the focus detection area 36.

  FIG. 6 is a circuit diagram illustrating the blue pixels 20B1 and 20B2 (see FIGS. 4 and 5) of the solid-state imaging device 3 in FIG. Since the pixel 20B2 has the same circuit configuration as the pixel 20B1, only the pixel 20B1 will be described here.

  As shown in FIG. 6, the blue pixel 20 </ b> B <b> 1 includes an imaging photodiode 41 as an imaging photoelectric conversion unit that mainly photoelectrically converts a blue wavelength component of incident light to obtain a charge to be a blue imaging signal; A first focus detection photodiode 42 as a first focus detection photoelectric conversion unit that obtains a charge to be a first focus detection signal by mainly photoelectrically converting wavelength components other than blue of incident light; A second focus detection photodiode 43 as a second focus detection photoelectric conversion unit that obtains a charge to be converted into a second focus detection signal by photoelectrically converting wavelength components other than blue light. is doing. The first and second focus detection photodiodes 42 and 43 selectively receive light beams from the exit pupil regions that are decentered in the opposite directions from the center of the exit pupil of the photographing lens 2, respectively, and perform photoelectric conversion. To do.

  The blue pixel 20B1 includes a floating diffusion (FD) 44 as a predetermined portion, a first transfer transistor 45 as a first transfer gate unit that transfers charges from the imaging photodiode 41 to the FD 44, and a first transfer transistor 45. A second transfer transistor 46 as a second transfer gate for transferring charge from the focus detection photodiode 42 to the FD 44, and a third transfer for transferring charge from the second focus detection photodiode 43 to the FD 44. A third transfer transistor 47 as a gate unit, a pixel amplifier 48 as an amplification unit that outputs a signal corresponding to the charge amount of the FD 44, and an FD reset transistor as a reset unit that discharges the charge of the FD 44 and resets the FD 44 49 and a selection switch for outputting the signal of the pixel amplifier 48 from the pixel. And a selection transistor 50.

  In the present embodiment, the first to third transfer transistors 45 to 47, the pixel amplifier 50, the FD reset transistor 49, and the selection transistor 50 are all configured by NMOS transistors.

  The gate electrode of the first transfer transistor 45 is commonly connected to each pixel row, and the drive signal φTGA is supplied from the vertical scanning circuit 21 through the drive wiring 23. The first transfer transistor 45 is simultaneously turned on for each row at a predetermined timing in accordance with the drive signal φTGA, and transfers charges to be an imaging signal from the imaging photodiode 41 to the FD 44.

  The gate electrode of the second transfer transistor 46 is commonly connected to each pixel row, and a drive signal φTGB is supplied from the vertical scanning circuit 21 through the drive wiring 23. The second transfer transistor 46 is turned on simultaneously for each row at a predetermined timing in accordance with the drive signal φTGB, and transfers the charge to be the first focus detection signal from the first focus detection photodiode 42 to the FD 44. To do.

  The gate electrode of the third transfer transistor 47 is commonly connected to each pixel row, and the drive signal φTGC is supplied from the vertical scanning circuit 21 through the drive wiring 23. The third transfer transistor 47 is simultaneously turned on for each row at a predetermined timing in accordance with the drive signal φTGC, and transfers the charge to be the second focus detection signal from the second focus detection photodiode 43 to the FD 44. To do.

  The gate electrodes of the selection transistors 50 are commonly connected to each pixel row, and a drive signal φS is supplied from the vertical scanning circuit 21 via the drive wiring 23. The gate electrode of the FD reset transistor 49 is commonly connected to each pixel row, and the drive signal φFDR is supplied from the vertical scanning circuit 21 through the drive wiring 23.

  In FIG. 6, one terminal of the photodiodes 41 to 42 and one terminal of the FD 44 are described as ground for convenience. However, in reality, as will be understood from FIGS. 10 to 12 described later, the potential of the P-type silicon substrate 51 is obtained.

  FIG. 7 is a schematic plan view schematically showing main elements of the blue pixel 20B1 of the solid-state imaging device 3 in FIG. FIG. 8 is a schematic plan view schematically showing some elements of the blue pixel 20B1 of the solid-state imaging device 3 in FIG. FIG. 9 is a schematic plan view schematically showing another part of the blue pixel 20B1 of the solid-state imaging device 3 in FIG. FIG. 10 is a schematic cross-sectional view along the line A-A ′ in FIG. 7. FIG. 11 is a schematic sectional view taken along line B-B ′ of FIG. 7. FIG. 12 is a schematic cross-sectional view along the line C-C ′ in FIG. 7.

  As shown in FIG. 7, an X axis and a Y axis that are orthogonal to each other are defined. The direction of the arrow in the X-axis direction is called the + X direction or + X side, and the opposite direction is called the -X direction or -X side, and the same applies to the Y-axis direction. A plane parallel to the XY plane coincides with the imaging surface (light receiving surface) of the solid-state imaging device 3. The arrangement in the X-axis direction is a row, and the arrangement in the Y-axis direction is a column. Incident light is incident from the front side of the drawing in FIG. These points are the same for the drawings described later.

  In FIG. 7, a first focus detection charge storage layer 53 constituting the first focus detection photodiode 42 and a second focus detection charge storage layer constituting the second focus detection photodiode 43. 54 is shown transparently. In FIG. 7, the drive wiring is omitted, and only the internal wiring 73 in the pixel is shown. 7 to 9, O represents the optical axis of the microlens 65.

  FIG. 8 mainly shows the imaging charge storage layer 52 constituting the imaging photodiode 41. For ease of understanding, FIG. 8 shows one of the conductive paths for guiding charges of the N-type diffusion layer 71 constituting a part of the FD 44 and the first and second focus detection charge storage layers 53 and 54, respectively. Also shown are diffusion portions 55 and 56 that constitute the respective portions and appear on the surface of the substrate 51. FIG. 8 also shows a separation layer 57 described later by a broken line.

  FIG. 9 mainly shows the first and second focus detection charge storage layers 53 and 54. FIG. 9 also shows deep diffusion portions 58 and 59 that respectively constitute other parts of the conductive paths that guide the charges of the first and second focus detection charge storage layers 53 and 54, respectively.

  In FIG. 11, main elements on the substrate 51 (that is, an interlayer insulating film 61 formed on the substrate 51, a wiring layer 62 also serving as a light shielding film having an opening 62a in the effective light receiving region of the pixel, a planarizing layer 63, 64 and microlens 65) are also shown, but they are not shown in FIGS. Microlenses 65 are provided on a one-to-one basis with respect to the pixel 20B1. The wiring layer 62 that also serves as a light shielding film is disposed on a substantially focal plane of the microlens 65. The regions of the FD 44, the deep diffusion portions 58 and 59, and the diffusion portions 55 and 56 appearing on the surface are shielded from light by the wiring layer 62. In FIG. 11, illustration of other wiring layers and the like disposed in the interlayer insulating film 61 is omitted.

  As shown in FIG. 10 to FIG. 12, desired impurity diffusion is performed on the P-type silicon substrate 51 as the first semiconductor layer on which the charge storage layers 52 to 54 and the like are to be arranged, and the charge storage layers 52 to 54 and Various transistors and the like are arranged. A P-type well or epitaxial layer is provided on an N-type silicon substrate, and the P-type well or epitaxial layer is used as the first semiconductor layer. On the other hand, charge storage layers 52 to 54, various transistors, and the like are provided. You may arrange.

  An N-type imaging charge storage layer 52 constituting a part of the imaging photodiode 41 is disposed on the P-type silicon substrate 51. The imaging charge storage layer 52 is formed by diffusion of N-type impurities. Here, the imaging photodiode 41 is a general PN photodiode. However, the imaging photodiode 41 is not limited thereto, and the imaging photodiode 41 is embedded by adding a P-type depletion prevention layer to the substrate surface side of the imaging charge storage layer 52. A photodiode may also be used. The imaging charge accumulation layer 52 accumulates charges that are to be converted into a blue imaging signal by mainly photoelectrically converting the blue wavelength component of the incident light. The surface of the imaging charge storage layer 52 is covered with a thin silicon oxide film 66.

  As shown in FIG. 11, the blue pixel 20B1 is not provided with a color filter.

  The blue wavelength band is about 450 nm, but light in the blue wavelength band is photoelectrically converted near the silicon surface. According to the simulation, light in the blue wavelength band is absorbed by 95% or more from the silicon surface at about 1 micron, and is absorbed by 100% at about 1.5 microns. Therefore, it is preferable that the imaging charge accumulation layer 52 for accumulating charges to be blue imaging signals has a thickness of 1 to 1.5 microns from the silicon surface by adding a depletion layer. Here, the thickness of the N-type imaging charge storage layer 52 is, for example, 0.5 microns.

  The charges accumulated in the imaging charge accumulation layer 52 are transferred to the FD 44 when the first transfer transistor 45 having the gate electrode 74 is turned on.

  The P-type silicon substrate 51 includes an N-type first focus detection charge storage layer 53 that constitutes a part of the first focus detection photodiode 42, and a second focus detection photodiode 43. An N-type second focus detection charge storage layer 54 that constitutes a part of the first focus detection layer 54 is disposed. Each of these charge storage layers 53 and 54 overlaps the imaging charge storage layer 52 via the P-type region of the P-type silicon substrate 51 when viewed from the incident direction of incident light. Has been placed.

  In the present embodiment, the first and second focus detection charge storage layers 53 and 54 are arranged on the back side of the imaging charge storage layer 52 (the side deeper than the imaging charge storage layer 52), and these The depth position and thickness of each are the same. In the present embodiment, the first and second focus detection charge storage layers 53 and 54 are arranged symmetrically with respect to the optical axis O of the microlens 65, and the first focus detection charge storage layer 53 is light. The second focus detection charge storage layer 54 is arranged on the + Y side with respect to the axis O, and is arranged on the −Y side with respect to the optical axis O. As a result, the first focus detection charge accumulation layer 53 selectively and effectively receives the light beam from the exit pupil region decentered from the center of the exit pupil of the photographing lens 2 to the −Y side. Charges to be a focus detection signal are accumulated. The second focus detection charge storage layer 54 selectively and effectively receives a light beam from the exit pupil region decentered from the center of the exit pupil of the photographing lens 2 toward the + Y side, and receives a second focus detection signal. Accumulate charge to become. The first and second focus detection charge storage layers 53 and 54 photoelectrically convert the wavelength components transmitted without being photoelectrically converted in the imaging charge storage layer 52. For this reason, incident light can be used efficiently. Since the first and second focus detection charge storage layers 53 and 54 have the same depth position and thickness, they store charges obtained by photoelectrically converting the same wavelength component of incident light. .

  The first and second charge storage layers 53 and 54 are also formed by diffusion of N-type impurities. However, it is not always necessary to dispose the first and second charge storage layers 53 and 54 at a predetermined depth from the surface of the silicon substrate 51 with high accuracy. This is because in the pixel 20B1 in which the first and second charge storage layers 53 and 54 are arranged, if the variation in depth is small, the signals can be sufficiently used as a focus detection signal by comparing the respective signals. Here, the upper surfaces of the first and second charge storage layers 53 and 54 are arranged at a position of about 3 microns from the surface of the silicon substrate 51. However, it is not limited to this. The depths of the first and second charge storage layers 53 and 54 are such that the imaging charge storage layer 52 and the depletion layer are not in contact with each other, and the blue wavelength of the photoelectric conversion source of charges stored in the imaging charge storage layer 52 A wavelength component different from the component (for example, a wavelength component in the visible range such as a red wavelength component and / or a green wavelength component) may have a depth at which charges obtained by photoelectric conversion are accumulated.

  The charges accumulated in the first focus detection charge accumulation layer 53 are guided to the N-type diffusion portion 55 provided on the surface of the silicon substrate 51 through the N-type deep diffusion portion 58. The charge introduced to the diffusion portion 55 on the surface is transferred to the FD 44 when the second transfer transistor 46 having the gate electrode 75 is turned on.

  The charges accumulated in the second focus detection charge accumulation layer 54 are guided to the N-type diffusion portion 56 provided on the surface of the silicon substrate 51 through the N-type deep diffusion portion 59. The charge guided to the diffusion portion 56 on the surface is transferred to the FD 44 when the third transfer transistor 47 having the gate electrode 76 is turned on.

  In the present embodiment, a separation layer 57 made of a P-type impurity diffusion layer is provided between the imaging charge storage layer 52 and the first and second focus detection charge storage layers 53 and 54. . The impurity concentration of the isolation layer 57 is higher than the impurity concentration of the silicon substrate 51. For example, the separation layer 57 is provided at a depth of 1.5 microns from the surface of the silicon substrate 51. By this separation layer 57, the charge generated on the front surface side from the separation layer 57 is captured by the imaging charge storage layer 52, and the charge generated on the back surface side from the separation layer 57 is the first and second focus detection charges. It is captured by the accumulation layers 53 and 54. Therefore, it is preferable that the imaging charge storage layer 52 captures charges generated by wavelength components other than the blue wavelength component, since this is further reduced. However, the separation layer 57 is not necessarily provided.

  As described above, when any of the first to third transfer transistors 45 to 47 is turned on, the charge of the corresponding charge storage layer among the charge storage layers 52 to 54 of the photodiodes 41 to 43 is changed to the FD 44. Forwarded to

  The FD 44 has two N-type diffusion layers 71 and 72 formed on the silicon substrate 51 so as to be separated from each other, and the N-type diffusion layers 71 and 72 are electrically connected by a wiring 73 to substantially Are configured as one floating diffusion.

  A gate electrode 74 is formed between the imaging charge storage layer 52 and the N-type diffusion layer 71 of the FD portion 44 via a thin silicon oxide film 66. The first transfer transistor 45 is configured as a MOS transistor having the gate electrode 74 as a gate and the imaging charge storage layer 52 and the N-type diffusion layer 71 of the FD portion 44 as a source or a drain.

  A gate electrode 75 is formed on the surface between the N-type diffusion portion 55 and the N-type diffusion layer 71 of the FD portion 44 via a thin silicon oxide film 66. The second transfer transistor 46 is configured as a MOS transistor having the gate electrode 75 as a gate and the N-type diffusion layer 55 of the N-type diffusion portion 55 and the FD portion 44 as a source or drain.

  A gate electrode 76 is formed on the surface between the N-type diffusion portion 56 and the N-type diffusion layer 71 of the FD portion 44 via a thin silicon oxide film 66. The third transfer transistor 47 is configured as a MOS transistor having the gate electrode 76 as a gate and the N-type diffusion layer 56 of the N-type diffusion portion 56 and the FD portion 44 as a source or drain.

  As shown in FIG. 10, the silicon substrate 51 includes N-type diffusion layers 81, 82, and 83 in addition to the N-type diffusion layer 72 along the line AA ′ in FIG. 7. Is formed. The N-type diffusion layer 81 is connected to the power supply VDD by a wiring (not shown). A gate electrode 85 is formed between the N-type diffusion layer 81 and the N-type diffusion layer 82 via a thin silicon oxide film 66. The pixel amplifier 48 is configured as a MOS transistor having the gate electrode 85 as a gate and the N-type diffusion layers 81 and 82 as sources or drains. Note that the gate electrode 85 is electrically connected to the FD 44 (N-type diffusion layers 71 and 72) by a wiring 73.

  A gate electrode 86 is disposed between the N-type diffusion layer 82 and the N-type diffusion layer 83 via a thin silicon oxide film 66. The selection transistor 50 is configured as a MOS transistor having the gate electrode 86 as a gate and the N-type diffusion layers 82 and 83 as sources or drains.

  A gate electrode 84 is disposed on the FD 44 between the N-type diffusion layer 72 and the N-type diffusion layer 81 via a thin silicon oxide film 66. The FD reset transistor 49 is configured as a MOS transistor having the gate electrode 84 as a gate and the N-type diffusion layer 72 and the N-type diffusion layer 81 as a source or drain.

  In the field portion, a thick oxide film 67 made of LOCOS is provided as an isolation region for isolating each element, and a P-type isolation diffusion portion 68 is provided therebelow.

  The configuration of the blue pixel 20B1 has been described above. In the blue pixel 20B1, the positional relationship in plan view of the microlens 65, the imaging charge storage layer 52, and the first and second focus detection charge storage layers 53 and 54 described above is further abstracted than in FIG. This is as shown in FIG.

  At the time of manufacturing, for example, a thin silicon oxide film is formed on the P-type silicon substrate 51. Next, deep diffusion portions 58 and 59 are formed by implanting phosphorus ions or the like into a predetermined region of the silicon substrate 51 a plurality of times. Next, phosphorus ions and the like are implanted to form first and second focus detection charge storage layers 53 and 54. Further, the separation layer 57 is formed by implanting boron ions or the like. Thereafter, boron ions or the like are implanted to form the separation diffusion portion 68, and then a thick oxide film 67 is formed by LOCOS. Next, phosphorus ion or the like is implanted to form the imaging charge storage layer 52, the surface diffusion portion 55, and the like. The blue pixel 20B1 described above can be obtained by appropriately setting the ion implantation conditions and the like.

  Next, the blue pixel 20B2 (see FIG. 5) of the solid-state imaging device 3 in FIG. 1 will be described. FIG. 14 is a diagram showing the positional relationship in plan view of the imaging charge storage layer 52 and the first and second focus detection charge storage layers 53 and 54 in the blue pixel 20B2, and corresponds to FIG. Yes. 14, elements that are the same as or correspond to those in FIG. 13 are given the same reference numerals, and redundant descriptions thereof are omitted.

  The blue pixel 20B2 is different from the blue pixel 20B1 in that the first focus detection charge storage layer 53 is disposed on the + Y side with respect to the optical axis O and the second focus detection is performed in the blue pixel 20B1. Whereas the charge storage layer 54 is disposed on the −Y side with respect to the optical axis O, in the blue pixel 20B2, the first focus detection charge storage layer 53 is on the −X side with respect to the optical axis O. And the second focus detection charge storage layer 54 is arranged on the + X side with respect to the optical axis O. Accordingly, although not shown in the drawing, each transistor, etc. It is only the point that arrangement has changed.

  Therefore, in the blue pixel 20B2, the first focus detection charge accumulation layer 53 selectively and effectively receives the light beam from the exit pupil region decentered from the center of the exit pupil of the photographing lens 2 to the + X side. The electric charge to be the first focus detection signal is accumulated. The second focus detection charge storage layer 54 selectively and effectively receives a light beam from the exit pupil region decentered to the −X side from the center of the exit pupil of the photographic lens 2, for the second focus detection. Accumulate charge to be a signal.

  Next, the red pixel 20R and the green pixel 20G (see FIGS. 4 and 5) of the solid-state imaging device 3 in FIG. 1 will be described.

  FIG. 15 is a circuit diagram showing the red pixel 20R and the green pixel 20G, and corresponds to FIG. FIG. 16 is a schematic cross-sectional view showing the red pixel 20R and the green pixel 20G, and corresponds to FIG. 15 and 16, the same or corresponding elements as those in FIGS. 5 and 11 are denoted by the same reference numerals, and redundant description thereof is omitted.

  The red pixel 20R is different from the blue pixel 20B1 only in the points described below. In the present embodiment, as shown in FIGS. 15 and 16, the red pixel 20R includes the first and second focus detection photodiodes 42 and 43 provided in the blue pixel 20B1, and the first and second focus detection photodiodes 42B and 43. The second transfer transistor is not provided. Accordingly, the first and second focus detection charge storage layers 53 and 54, the separation layer 57, the surface diffusion portions 55 and 56, and the deep diffusion portions 58 and 59 are not provided in the red pixel 20R. .

  Since the first and second focus detection charge storage layers 53 and 54 and the separation layer 57 are not provided in the red pixel 20R, not only the red wavelength component but also the blue wavelength component and the green wavelength component of the incident light are provided. If incident on the imaging photodiode 41, the imaging photodiode 41 also photoelectrically converts red, blue, and green wavelength components, and the imaging charge storage layer 52 accumulates charges from these components. become. However, the red pixel 20R is provided with a red color filter 88R that selectively transmits a red wavelength component between the planarization layers 63 and 64, as shown in FIG. Therefore, only the red wavelength component of the incident light is incident on the red pixel 20R. For this reason, in the red pixel 20R, the imaging photodiode 41 is an imaging photoelectric conversion unit that mainly photoelectrically converts the red wavelength component of incident light to obtain a charge to be a red imaging signal, and the imaging photodiode 41 The imaging charge storage layer 52 constituting 41 stores the charge to be converted into a blue imaging signal by mainly photoelectrically converting the blue wavelength component of the incident light.

  The green pixel 20G has the same configuration as the red pixel 20R except that a green color filter 88G that selectively transmits a green wavelength component is provided instead of the red color filter 88R.

  As described above, in the present embodiment, the pixel 20R and the pixel 20G are configured in the same manner as the red pixel and the green pixel used in the conventional normal solid-state imaging device, respectively. However, the configuration of the pixel 20R and the pixel 20G is not limited to such a configuration.

  Next, each example of the driving procedure of the solid-state imaging device 3 will be described with reference to FIGS. 17 to 19.

  FIG. 17 is a timing chart showing a driving procedure of the solid-state image sensor 3 in the focus detection mode (an operation mode in which a focus detection signal is read out from the solid-state image sensor 3 but no image pickup signal is read out). FIG. 18 is a timing chart showing the driving procedure of the solid-state image sensor 3 in the image-capturing mode (an operation mode in which the image-capturing signal is read from the solid-state image sensor 3 but the focus detection signal is not read). FIG. 19 shows a driving procedure of the solid-state image pickup device 3 in the simultaneous focus detection / imaging mode (operation mode in which the focus detection signal is read out while reading out the image pickup signal from the solid-state image pickup device 3). It is a timing chart which shows. Note that a transistor included in each pixel is an NMOS transistor, and is turned on in response to a high level (high) driving signal.

  First, a driving procedure in the focus detection mode will be described with reference to FIG. In all rows, φFDR is set high, the FD reset transistor 49 is turned on, and the FD 44 is reset except during a period when φS is set high and a row is selected. However, the present invention is not necessarily limited to this, and φFDR may be made high only for a necessary period.

  First, in the period from time t1 to time t2, φTGB (n) in the n-th row is set high, the second transfer transistor 46 is turned on, and the first focus detection photodiode 42 in the n-th row is turned on. Reset. From time t2, the exposure time of the first focus detection photodiode 42 in the n-th row starts.

  Next, in a period from time t3 to time t4, φTGC (n) is set high, the third transfer transistor 47 is turned on, and the second focus detection photodiode 43 in the n-th row is reset. From time t4, the exposure time of the second focus detection photodiode 43 in the n-th row starts.

  Thereafter, at time t5 immediately before the time t6 when the exposure time of the first focus detection photodiode 42 in the n-th row ends, φFDR (n) is set low and the FD reset transistor 49 in the n-th row is turned off. When the reset of the FD 44 is completed, φS (n) is set high, the n-th row selection transistor 50 is turned on, the n-th row selection is started, and the source follower by the n-th row pixel amplifier 48 is started. Reading is started. Between time t5 and time t6, the dark level of the nth row (a signal output from the pixel amplifier 48 of the nth row corresponding to the reset state of the FD 44) is transmitted from the pixel amplifier 48 to the vertical signal line 25. And is clamped (stored) in the CDS circuit 27.

  Next, at time t6, φTGB (n) is set high, and the second transfer transistor 46 in the n-th row is turned on. As a result, the charge accumulated in the first focus detection photodiode 42 in the n-th row is transferred to the FD 44, and the exposure time of the first focus detection photodiode 42 in the n-th row is completed. The potential fluctuation due to the charge transferred to the FD 44 is clamped from the pixel amplifier 48 to the CDS circuit 27 through the vertical signal line 25, and the CDS circuit 27 acquires a difference signal between this signal and the previous dark level. This signal becomes the first focus detection signal based on the light beam from the region decentered to one of the exit pupils of the photographing lens 2. At time t7, φTGB (n) is set to low, and the second transfer transistor 46 in the n-th row is turned off. These first focus detection signals in the n-th row are output to the outside via the horizontal signal line 28 and the output amplifier 29 by the drive signal of the horizontal scanning circuit 22.

  Next, after the CDS circuit 27 is reset, at time t8, φFDR (n) is set high again, the FD reset transistor 49 is turned on, and the FD 44 is reset. Thereafter, at time t9, φFDR (n) is set low, the n-th row FD reset transistor 49 is turned off, and the reset of the FD 44 is completed. From time t9 to time t10, the dark level of the nth row is clamped from the pixel amplifier 48 to the CDS circuit 27 via the vertical signal line 25.

  Next, at time t10, φTGC (n) is set high and the third transfer transistor 47 is turned on. As a result, the electric charge accumulated in the second focus detection photodiode 43 in the n-th row is transferred to the FD 44, and the exposure time of the second focus detection photodiode 43 in the n-th row ends. The potential fluctuation due to the charge transferred to the FD 44 is clamped from the pixel amplifier 48 to the CDS circuit 27 through the vertical signal line 25, and the CDS circuit 27 acquires a difference signal between this signal and the previous dark level. This signal becomes the second focus detection signal based on the light beam from the region decentered to the other exit pupil of the photographing lens 2. At time t11, φTGC (n) is set low, and the third transfer transistor 47 in the n-th row is turned off. These second focus detection signals in the n-th row are output to the outside via the horizontal signal line 28 and the output amplifier 29 by the drive signal of the horizontal scanning circuit 22.

  Thereafter, at time t12, φFDR (n) is set to high to turn on the FD reset transistor 49, and resetting of the FD 44 is started, and φS (n) is set to low to select the n-th row selection transistor 50. It is turned off and the row selection for the nth row is completed.

  As shown in FIG. 17, φTGA (n) is always kept low, and the first transfer transistor 45 is kept off. Therefore, reading of the imaging signal based on the charge of the imaging photodiode 41 is not performed.

  Next, the operation proceeds to the selection operation of the next (n + 1) th row through the horizontal blanking period. Since the operation similar to that of the nth row is repeated for the (n + 1) th row, the description thereof is omitted here. In this way, when signals are read from all rows, the focus detection mode is terminated. Note that if an overflow from the charge storage layer 52 for imaging is disliked, φTGA (n) may be set high during the period from time t1 to time t5.

  Next, a driving procedure in the imaging mode will be described with reference to FIG. In all rows, φFDR is set high, the FD reset transistor 49 is turned on, and the FD 44 is reset except during a period when φS is set high and a row is selected. However, the present invention is not necessarily limited to this, and φFDR may be made high only for a necessary period.

  First, at time t21, φTGA (n), φTGB (n), and φTGC (n) in the n-th row are set high, and the imaging photodiode 41 and the first and second focus detection photodiodes in the n-th row. 42 and 43 are all turned on, and these photodiodes 41, 42 and 43 are reset.

  Next, at time t22, φTGA (n) is set low, the first transfer transistor 45 is turned off, and the exposure time of the imaging photodiode 41 starts. Until time t23, φTGB (n) and φTGC (n) remain high, and the first and second focus detection photodiodes 42 and 43 continue to be reset. However, φTGB (n) and φTGC (n) may be low at time t22, or may remain low at all times.

  Next, at time t23, φTGB (n), φTGC (n), and φFDR (n) are set to low, and resetting of the first and second focus detection photodiodes 42, 43 and FD 44 is completed. φS (n) is set to high to turn on the selection transistor 50 in the n-th row, the row selection in the n-th row is started, and the source follower reading by the pixel amplifier 48 in the n-th row is started. Between time t23 and time t24, the dark level of the nth row (a signal output from the pixel amplifier 48 of the nth row corresponding to the reset state of the FD 44) is transmitted from the pixel amplifier 48 to the vertical signal line 25. To the CDS circuit 27.

  Next, at time t24, φTGA (n) is set high, and the first transfer transistor 45 in the n-th row is turned on. As a result, the charges accumulated in the n-th imaging photodiode 41 are transferred to the FD 44, and the exposure time of the n-th imaging photodiode 41 ends. The potential fluctuation due to the charge transferred to the FD 44 is clamped from the pixel amplifier 48 to the CDS circuit 27 through the vertical signal line 25, and the CDS circuit 27 acquires a difference signal between this signal and the previous dark level. This signal becomes an imaging signal. At time t25, φTGA (n) is set low and the first transfer transistor 45 in the n-th row is turned off. These n-th row image pickup signals are output to the outside via the horizontal signal line 28 and the output amplifier 29 by the drive signal of the horizontal scanning circuit 22.

  Thereafter, at time t26, φFDR (n) is set to high to turn on the FD reset transistor 49, and resetting of the FD 44 is started, and φS (n) is set to low to select the n-th row selection transistor 50. It is turned off and the row selection for the nth row is completed.

  As shown in FIG. 18, φTGB (n) and φTGC (n) are kept low during a period in which φFDR (n) is low and φS is high (period from time t23 to time 26). . Therefore, reading of the first and second focus detection signals based on the charges of the first and second focus detection photodiodes 42 and 43 is not performed.

  Next, the operation proceeds to the selection operation of the next (n + 1) th row through the horizontal blanking period. Since the operation similar to that of the nth row is repeated for the (n + 1) th row, the description thereof is omitted here. In this way, when signals are read from all rows, the imaging mode is terminated.

  Next, a driving procedure in the simultaneous focus detection / imaging mode will be described with reference to FIG. In all rows, φFDR is set high, the FD reset transistor 49 is turned on, and the FD 44 is reset except during a period when φS is set high and a row is selected. However, the present invention is not necessarily limited to this, and φFDR may be made high only for a necessary period.

  First, in a period from time t31 to time t32, φTGA (n) in the n-th row is set to high, the first transfer transistor 45 is turned on, and the imaging photodiode 41 in the n-th row is reset. From time t32, the exposure time of the imaging photodiode 41 in the n-th row starts.

  Next, in the period from time t33 to time t34, φTGB (n) in the n-th row is set high, the second transfer transistor 46 is turned on, and the first focus detection photodiode 42 in the n-th row is turned on. Reset. From time t4, the exposure time of the first focus detection photodiode 42 in the n-th row starts.

  Next, in a period from time t35 to time t36, φTGC (n) is set high, the third transfer transistor 47 is turned on, and the second focus detection photodiode 43 in the n-th row is reset. . From time t36, the exposure time of the second focus detection photodiode 43 in the n-th row starts.

  After that, at time t37 immediately before time t38 when the exposure time of the n-th imaging photodiode 41 ends, φFDR (n) is set to low, the n-th FD reset transistor 49 is turned off, and the FD 44 is reset. Is finished, φS (n) is made high, the n-th row selection transistor 50 is turned on, the row selection for the n-th row is started, and the source follower reading by the pixel amplifier 48 in the n-th row is started. The Between time t37 and time t38, the dark level of the nth row (a signal output from the pixel amplifier 48 of the nth row corresponding to the reset state of the FD 44) is transmitted from the pixel amplifier 48 to the vertical signal line 25. To the CDS circuit 27.

  Next, at time t38, φTGA (n) is set high and the first transfer transistor 45 in the n-th row is turned on. As a result, the charges accumulated in the n-th imaging photodiode 41 are transferred to the FD 44, and the exposure time of the n-th imaging photodiode 41 ends. The potential fluctuation due to the charge transferred to the FD 44 is clamped from the pixel amplifier 48 to the CDS circuit 27 through the vertical signal line 25, and the CDS circuit 27 acquires a difference signal between this signal and the previous dark level. This signal becomes an imaging signal. At time t39, φTGA (n) is set low and the first transfer transistor 45 in the n-th row is turned off. These n-th row image pickup signals are output to the outside via the horizontal signal line 28 and the output amplifier 29 by the drive signal of the horizontal scanning circuit 22.

  Next, after the CDS circuit 27 is reset, at time t40, φFDR (n) is set to high again, the FD reset transistor 49 is turned on, and the FD 44 is reset. Thereafter, at time t41, φFDR (n) is set low, the n-th row FD reset transistor 49 is turned off, and the reset of the FD 44 is completed. Between time t41 and time t42, the dark level of the nth row is clamped from the pixel amplifier 48 to the CDS circuit 27 via the vertical signal line 25.

  Next, at time t42, φTGB (n) is set high and the second transfer transistor 46 is turned on. As a result, the charge accumulated in the first focus detection photodiode 42 in the n-th row is transferred to the FD 44, and the exposure time of the first focus detection photodiode 42 in the n-th row is completed. The potential fluctuation due to the charge transferred to the FD 44 is clamped from the pixel amplifier 48 to the CDS circuit 27 through the vertical signal line 25, and the CDS circuit 27 acquires a difference signal between this signal and the previous dark level. This signal becomes the first focus detection signal based on the light beam from the region decentered to one of the exit pupils of the photographing lens 2. At time t43, φTGB (n) is set low and the second transfer transistor 46 in the n-th row is turned off. These first focus detection signals in the n-th row are output to the outside via the horizontal signal line 28 and the output amplifier 29 by the drive signal of the horizontal scanning circuit 22.

  Next, after the CDS circuit 27 is reset, at time t44, φFDR (n) is set high again, the FD reset transistor 49 is turned on, and the FD 44 is reset. Thereafter, at time t45, φFDR (n) is set low, the n-th row FD reset transistor 49 is turned off, and the reset of the FD 44 is completed. From time t45 to time t46, the dark level of the nth row is clamped from the pixel amplifier 48 to the CDS circuit 27 via the vertical signal line 25.

  Next, at time t46, φTGC (n) is set high and the third transfer transistor 47 is turned on. As a result, the electric charge accumulated in the second focus detection photodiode 43 in the n-th row is transferred to the FD 44, and the exposure time of the second focus detection photodiode 43 in the n-th row ends. The potential fluctuation due to the charge transferred to the FD 44 is clamped from the pixel amplifier 48 to the CDS circuit 27 through the vertical signal line 25, and the CDS circuit 27 acquires a difference signal between this signal and the previous dark level. This signal becomes the second focus detection signal based on the light beam from the region decentered to the other exit pupil of the photographing lens 2. At time t47, φTGC (n) is set low and the third transfer transistor 47 in the n-th row is turned off. These second focus detection signals in the n-th row are output to the outside via the horizontal signal line 28 and the output amplifier 29 by the drive signal of the horizontal scanning circuit 22.

  Thereafter, at time t48, φFDR (n) is set to high to turn on the FD reset transistor 49, and resetting of the FD 44 is started, and φS (n) is set to low to select the n-th row selection transistor 50. It is turned off and the row selection for the nth row is completed.

  Next, the operation proceeds to the selection operation of the next (n + 1) th row through the horizontal blanking period. Since the operation similar to that of the nth row is repeated for the (n + 1) th row, the description thereof is omitted here. Thus, when signals are read from all rows, the simultaneous focus detection / imaging mode is terminated.

  In the example shown in FIGS. 17 to 19, the start and end of exposure are determined by the electronic shutter operation. However, the start and end of exposure may be determined using a mechanical shutter mechanism. In this case, for example, the exposure time may be determined by the mechanical shutter that is opened after the exposure by the electronic shutter is started and the electronic shutter is closed after the mechanical shutter is closed.

  Next, an example of the operation of the electronic camera 1 according to the present embodiment will be described with reference to FIG. 1 again.

  The microprocessor 9 in the electronic camera 1 drives the imaging control unit 4 in synchronization with the half-press operation of the release button. The imaging control unit 4 reads the focus detection signal from the solid-state imaging device 3 and stores it in the memory 7 by the operation in the focus detection mode described with reference to FIG.

  When a focus detection signal is output from the solid-state imaging device 3 according to a command from the imaging control unit 4 and accumulated in the memory 7, the focus calculation unit 10 uses this signal to perform focus detection calculation processing according to the pupil division phase difference method. And the defocus amount is obtained as a detection signal indicating the focus adjustment state of the photographic lens 2.

  Here, the focus adjustment mode that is currently set is a mode in which focus adjustment is performed based only on the focus detection area 35 shown in FIGS. 3 and 4, for example (hereinafter referred to as “focus detection area 35 mode”). In this case, the focus calculation unit 10 uses the first and second focus detection signals of all the blue pixels 20B1 in the focus detection region 35 among the focus detection signals captured in the memory 7 to perform pupil division. Focus detection calculation processing according to the phase difference method is performed, and the defocus amount is obtained as a detection signal indicating the focus adjustment state of the photographing lens 2.

  When the currently set focus adjustment mode is a mode in which focus adjustment is performed based on, for example, all the focus detection areas 32 to 37 shown in FIG. 3 (hereinafter referred to as “all focus detection area mode”), In addition to calculating the defocus amount with respect to the focus detection region 35 as described above, the focus calculation unit 10 similarly calculates the defocus amount with respect to each focus detection region 32-34, 36, and 37 as well. To do. When the defocus amount is calculated with respect to the focus detection region 36, as can be understood from FIG. 5, the calculation is performed using the first and second focus detection signals of all the blue pixels 20B2 in the focus detection region 36. .

  The defocus amount detected by the focus calculation unit 10 is transmitted to the lens control unit 2a. The lens control unit 2a drives the photographing lens 2 based on the transmitted defocus amount to focus the photographing lens 2 on the subject.

  At this time, if the currently set focus adjustment mode is the focus detection region 35 mode, the lens control unit 2a takes a picture so that the defocus amount becomes zero based on the defocus amount related to the focus detection region 35. The lens 2 is driven. If the currently set focus adjustment mode is the all-focus detection area mode, the lens control unit 2a determines the focus adjustment state after adjustment determined based on the defocus amount of each focus detection area obtained previously. The photographic lens 2 is driven so that

  Thereafter, the microprocessor 9 in the electronic camera 1 captures an image from the solid-state image sensor 3 by the operation of the imaging mode described with reference to FIG. 18 using the imaging control unit 4 in synchronization with the full pressing operation of the release button. The signal for use is read and stored in the memory 7. Subsequently, the microprocessor 9 performs a desired process in the image processing unit 13 or the image compression unit 12 as necessary based on a command from the operation unit 9a, and causes the recording unit 11 to output a processed signal, thereby recording the recording medium. Record in 11a.

  Further, the microprocessor 9 in the electronic camera 1 drives the imaging control unit 4 in response to an instruction to shoot a moving image or the like by operating the operation unit 9a. The imaging control unit 4 reads both the focus detection signal and the imaging signal from the solid-state imaging device 3 substantially simultaneously and accumulates them in the memory 7 by the simultaneous focus detection / imaging mode described with reference to FIG. . In this manner, the imaging signal is read out and stored in the memory 7 while the focus calculation unit 10 calculates the defocus amount based on the focus detection signal obtained substantially simultaneously and the lens control unit 2a according to the calculation. Focus. In this case as well, the defocus amount is calculated and the photographing lens 2 is driven in accordance with the currently set focus adjustment mode. In this way, a moving image can be captured while performing a focusing operation that follows a moving object or the like.

  According to the present embodiment, for the blue pixels 20B1 and 20B2, in addition to the imaging photodiode 41 that obtains a charge to be a blue imaging signal in one pixel, the first and second focus detection signals Since the first and second focus detection photodiodes 42 and 43 for obtaining a charge to be a signal are provided, both a blue imaging signal and a focus detection signal can be obtained from one pixel. Therefore, according to the present embodiment, it is possible to avoid deterioration in image quality due to a state similar to a pixel defect while the solid-state imaging device 3 also has a function as a focus detection device.

  In the present embodiment, regarding the blue pixels 20B1 and 20B2, in one pixel, the imaging photodiode 41 and the first and second focus detection photodiodes 42 and 43 overlap in the incident light incident direction. The wavelength component of incident light that is mainly photoelectrically converted by the imaging photodiode 41 is different from the wavelength component of incident light that is mainly photoelectrically converted by the first and second focus detection photodiodes 42 and 43. ing. Therefore, according to the present embodiment, unlike the solid-state imaging device disclosed in Patent Document 3, it is not necessary to divide the imaging photodiode 41 into two, and no dead zone occurs in the imaging photodiode 41. Therefore, according to the present embodiment, the utilization efficiency of incident light with respect to a blue imaging signal is increased.

  [Second Embodiment]

  FIG. 20 is a diagram schematically illustrating a pixel arrangement of a solid-state imaging element of an electronic camera as an imaging apparatus according to the second embodiment of the present invention. 20, elements that are the same as or correspond to those in FIGS. 4 and 5 are given the same reference numerals, and redundant descriptions thereof are omitted.

  This embodiment is basically different from the first embodiment only in the arrangement of pixels in the solid-state imaging device 3. In the present embodiment, the pixels 20R, 20G, 20B1, and 20B2 in the solid-state imaging device 3 are arranged in a pattern as shown in FIG. FIG. 20 corresponds to an enlarged part of the imaging region 31.

  In the present embodiment, as shown in FIG. 20, while adopting an arrangement according to the Bayer arrangement, blue pixels adjacent to each other in the X-axis direction and the Y-axis direction with one green pixel 20G interposed therebetween are pixels. 20B1 and the pixel 20B2, and are arranged so as not to be the pixels 20B1 or the pixels 20B2.

  In the first embodiment, the focus detection area is determined in advance as shown in FIG. 3, but in this embodiment, for example, an arbitrary column including the green pixel 20G and the blue pixels 20B1 and 20B2 In addition, a part of a row can be arbitrarily arbitrarily designated as a focus detection region. In this case, when a part of the column in the Y-axis direction including the green pixel 20G and the blue pixels 20B1 and 20B2 is designated as the focus detection region, the first and first pixels of all the blue pixels 20B1 in the focus detection region are designated. The defocus amount is calculated using the two focus detection signals. When a part of the row in the X-axis direction including the green pixel 20G and the blue pixels 20B1 and 20B2 is designated as the focus detection region, the first and second focus points of all the blue pixels 20B2 in the focus detection region. The defocus amount is calculated using the detection signal.

  Also in this embodiment, the same advantages as those in the first embodiment can be obtained.

  [Third Embodiment]

  FIG. 21 is a diagram schematically showing a pixel arrangement of a solid-state image sensor of an electronic camera as an image pickup apparatus according to the third embodiment of the present invention, in which the vicinity of the focus detection area 35 in FIG. 3 is enlarged. Equivalent to. FIG. 22 is another view schematically showing the pixel arrangement of the solid-state imaging device 3 of the electronic camera 1 according to the present embodiment, and corresponds to an enlarged view of the vicinity of the focus detection region 36 in FIG. 21 and 22, elements that are the same as or correspond to those in FIGS. 4 and 5 are given the same reference numerals, and redundant descriptions thereof are omitted.

  This embodiment is basically different from the first embodiment in that a focus detection signal is output instead of the blue pixels 20B1 and 20B2 configured to output a focus detection signal. The red pixels 20R1 and 20R2 configured to output focus detection signals instead of the red pixels 20R that cannot output the focus detection signals and the point that the blue pixels 20B that cannot be obtained are used. It is only the point where is used.

  In FIG. 21 and FIG. 22, the pixel 20 </ b> B is denoted by the symbol “B”, the pixel 20 </ b> R <b> 1 is denoted by the symbol “R1”, and the pixel 20 </ b> R <b> 2 is denoted by the symbol “R2”.

  In the present embodiment, as shown in FIGS. 21 and 22, the red pixels 20R1 and 20R2, the green pixel 20G, and the blue pixel 20B are arranged according to the Bayer array.

  In the present embodiment, the focus detection area 35 in FIG. 3 extending in the Y-axis direction is one column in the Y-axis direction in which green pixels 20G and red pixels are alternately arranged as shown in FIG. Part. In the focus detection area 35, a red pixel 20R1 is used as a red pixel. The focus detection regions 33 and 34 in FIG. 3 extending in the Y-axis direction are the same as the focus detection region 35.

  Further, in the present embodiment, the focus detection region 36 in FIG. 3 extending in the X-axis direction is a row in the X-axis direction in which green pixels 20G and red pixels are alternately arranged as shown in FIG. Is part of. In the focus detection area 36, a red pixel 20R2 is used as a red pixel. The focus detection areas 36 and 37 in FIG. 3 extending in the X-axis direction are the same as the focus detection area 35.

  Although not shown in the drawing, the blue pixel 20B is the first except that a blue color filter 88B (not shown) that selectively transmits a blue wavelength component is provided instead of the red color filter 88R. This is the same as the red pixel 20R in the embodiment.

  Next, the red pixel 20R1 will be described with reference to FIGS. The circuit configuration of the red pixel 20R1 is the same as the circuit configuration of the blue pixel 20B1 shown in FIG.

  FIG. 23 is a schematic plan view schematically showing main elements of the red pixel 20R1. FIG. 24 is a schematic plan view schematically showing some elements of the red pixel 20R1. FIG. 25 is a schematic plan view schematically showing another part of the red pixel 20R1. FIG. 26 is a schematic cross-sectional view along the line D-D ′ in FIG. 23. 23 to 26, the same or corresponding elements as those in FIGS. 7 to 12 are denoted by the same reference numerals, and redundant description thereof is omitted.

  In FIG. 23, a broken line is shown through the imaging charge storage layer 52 constituting the imaging photodiode 41. In FIG. 23, the drive wiring is omitted, and only the internal wiring 73 in the pixel is shown.

  FIG. 24 mainly shows an imaging charge storage layer 52 that constitutes the imaging photodiode 41. FIG. 24 also shows a deep N-type diffusion portion 91 and an N-type diffusion portion 92 appearing on the surface, each of which constitutes a part of a conductive path for guiding the charge of the imaging charge storage layer 52. In FIG. 24, the separation layer 57 is also indicated by a broken line.

  FIG. 25 mainly shows a first focus detection charge storage layer 53 that constitutes the first focus detection photodiode 42 and a second focus detection that constitutes the second focus detection photodiode 43. A charge storage layer 54 is shown. For easy understanding, FIG. 25 also shows an N-type diffusion layer 71, a deep diffusion portion 91, and a surface diffusion portion 92 that constitute a part of the FD 44. Although not shown, regions of the floating diffusion 71, the deep diffusion portion 91, and the diffusion portion 92 appearing on the surface are shielded from light by a wiring layer 62 (not shown) that also serves as a light shielding film.

  In FIG. 26, unlike FIG. 11, main elements on the substrate 51 (that is, an interlayer insulating film 61 formed on the substrate 51, and a wiring layer serving also as a light shielding film having an opening 62a in the effective light receiving region of the pixel. 62, the planarization layers 63 and 64, and the microlens 65) are not shown. However, those elements are also provided in the red pixel 20R1. Note that the red pixel 20R1 is also not provided with a color filter, as is the case with the blue pixel 20B1 in the first embodiment.

  The red pixel 20R1 is basically different from the blue pixel 20B1 in that the imaging charge storage layer 52 constituting the imaging photodiode 41 is not disposed on the surface of the substrate 51 but in a deep region in the depth direction. And the first and second focus detection charge storage layers 53 and 54 constituting the first and second focus detection photodiodes 42 and 43, respectively, are disposed near the surface of the substrate 51. It is.

  As a result, in the red pixel 20R1, the imaging charge storage layer 52 accumulates the charge to be converted into a red imaging signal by mainly photoelectrically converting the red wavelength component of the incident light deep in the silicon substrate 51. The imaging photodiode 41 having this obtains a charge to be a red imaging signal by mainly photoelectrically converting the red wavelength component of the incident light. Further, in the red pixel 20R1, the first and second focus detection charge storage layers 53 and 54 mainly photoelectrically convert the blue wavelength component of the incident light near the surface of the silicon substrate 51, respectively. And charge to be the second focus detection signal are accumulated. The first and second focus detection photodiodes 42 and 43 having the first and second focus detection charge storage layers 53 and 54, respectively, mainly photoelectrically convert the blue wavelength component of the incident light, respectively. Charges to be the first and second focus detection signals are obtained.

  The red pixel 20R2 can be obtained by deforming the red pixel 20R1 in the same manner as the blue pixel 20B1 is deformed to obtain the blue pixel 20B2. That is, in the red pixel 20R2, as shown in FIGS. 23 and 24, the first focus detection charge storage layer 53 is arranged on the + Y side with respect to the optical axis O and the second focus detection charge. Although the storage layer 54 is arranged on the −Y side with respect to the optical axis O, although not shown in the drawing, in the red pixel 20R2, the first focus detection charge storage layer 53 has the optical axis O. The second focus detection charge storage layer 54 is disposed on the + X side with respect to the optical axis O.

  Also in this embodiment, the same advantages as those in the first embodiment can be obtained.

  A modification similar to that obtained by modifying the first embodiment to obtain the second embodiment may be applied to the present embodiment.

  [Fourth Embodiment]

  FIG. 27 is a diagram schematically illustrating a pixel arrangement of a solid-state imaging element of an electronic camera as an imaging apparatus according to the fourth embodiment of the present invention. In FIG. 27, elements that are the same as or correspond to elements in FIGS. 4, 5, 21, and 22 are given the same reference numerals, and redundant descriptions thereof are omitted.

  This embodiment is basically different from the third embodiment only in the arrangement of pixels in the solid-state imaging device 3. In the present embodiment, the pixels 20B1, 20R2, and 20G described so far are arranged in a pattern as shown in FIG. FIG. 27 corresponds to an enlarged view of a part of the imaging region 31. In the present embodiment, as shown in FIG. 27, the pixels 20B1, 20R2, and 20G are arranged in a Bayer array.

  In the present embodiment, for example, a part of an arbitrary column including the green pixel 20G and the blue pixel 20B1 and a part of an arbitrary row including the green pixel 20G and the red pixel 20R2 are arbitrarily arbitrarily set. It can be designated as a focus detection area. In this case, when a part of an arbitrary column including the green pixel 20G and the blue pixel 20B1 is designated as the focus detection region, the first and second focus detections of all the blue pixels 20B1 in the focus detection region. The defocus amount is calculated using the business signal. When a part of an arbitrary row including the green pixel 20G and the red pixel 20R2 is designated as the focus detection region, the first and second focus detection signals of all the red pixels 20R2 in the focus detection region are used. To calculate the defocus amount.

  Also in this embodiment, the same advantages as those in the first embodiment can be obtained.

  [Fifth Embodiment]

  FIG. 28 is a diagram schematically illustrating a pixel arrangement of a solid-state imaging device of an electronic camera as an imaging apparatus according to the fifth embodiment of the present invention. 28, elements that are the same as or correspond to those in FIGS. 4, 5, 21, and 22 are given the same reference numerals, and redundant descriptions thereof are omitted.

  This embodiment is basically different from the first embodiment in that a focus detection signal is output instead of the blue pixels 20B1 and 20B2 configured to output a focus detection signal. The green pixels 20G1 and 20G2 configured to output a focus detection signal instead of the green pixel 20G that cannot output the focus detection signal and the point that the blue pixel 20B that cannot be obtained is used. It is only the point where is used.

  In FIG. 28, the pixel 20G1 is denoted by reference symbol “G1”, and the pixel 20G2 is denoted by reference symbol “G2”.

  In the present embodiment, as shown in FIGS. 21 and 22, the red pixels 20R, the green pixels 20G1 and 20G2, and the blue pixels 20B are arranged according to the Bayer array.

  Although not shown in the drawing, the circuit configuration of the green pixel 20G1 is the same as the circuit configuration of the blue pixel 20B1 shown in FIG.

  Although not shown in the drawing, the green pixel 20G1 is basically different from the blue pixel 20B1 in that the imaging charge storage layer 52 constituting the imaging photodiode 41 is not the surface of the substrate 51, The green wavelength component is disposed in an intermediate deep region suitable for accumulating the photoelectrically converted charge, and the first and second focus detection photodiodes 42 and 43, respectively. The second focus detection charge storage layers 53 and 54 are arranged near the surface of the substrate 51 or at a position deeper than the imaging charge storage layer 52.

  As a result, in the green pixel 20G1, the imaging charge storage layer 52 has the charge that should be converted into a green imaging signal by mainly photoelectrically converting the green wavelength component of the incident light at an intermediate depth of the silicon substrate 51. accumulate. The imaging photodiode 41 having this obtains a charge to be a green imaging signal by mainly photoelectrically converting the green wavelength component of the incident light. In the green pixel 20R1, the blue wavelength component or red wavelength component of incident light is mainly photoelectrically converted near the surface of the silicon substrate 51 or deeply in the first and second focus detection charge storage layers 53 and 54. Thus, the charges to be the first and second focus detection signals of blue or red are respectively stored. The first and second focus detection photodiodes 42 and 43 each having the first and second focus detection charge storage layers 53 and 54 mainly photoelectrically convert the blue wavelength component or red wavelength component of incident light. Charges to be the first and second focus detection signals of blue or red, respectively, are obtained.

  The green pixel 20G2 can be obtained by deforming the green pixel 20G1 in the same manner as the blue pixel 20B2 is obtained by deforming the blue pixel 20B1.

  Also in this embodiment, the same advantages as those in the first embodiment can be obtained.

  [Sixth Embodiment]

  FIG. 29 is a diagram schematically showing a pixel arrangement of a solid-state image sensor of an electronic camera as an image pickup apparatus according to the sixth embodiment of the present invention, in which the vicinity of the focus detection region 35 in FIG. 3 is enlarged. Equivalent to. FIG. 30 is another view schematically showing the pixel arrangement of the solid-state imaging device 3 of the electronic camera 1 according to this embodiment, and corresponds to an enlarged view of the vicinity of the focus detection region 36 in FIG. 29 and 30, elements that are the same as or correspond to those in FIGS. 4 and 5 are given the same reference numerals, and redundant descriptions thereof are omitted.

  This embodiment is basically different from the first embodiment in that a focus detection signal is output instead of the blue pixels 20B1 and 20B2 configured to output a focus detection signal. The only point is that the blue pixels 20B3, 20B4, 20B5, and 20B6 configured to be obtained are used.

  In FIG. 29 and FIG. 30, the pixel 20B3 is denoted by reference numeral “B3”, the pixel 20B4 is denoted by reference numeral “B4”, the pixel 20B5 is denoted by reference numeral “B5”, and the pixel 20B6 is denoted by reference numeral “B6”. Is attached. 29 and 30, the symbol “B *” indicates any one of the blue pixels 20B3, 20B4, 20B5, and 20B6.

  In the present embodiment, as shown in FIGS. 29 and 30, the red pixel 20R, the green pixel 20G, and the blue pixels 20B3, 20B4, 20B5, and 20B6 are arranged according to the Bayer array.

  In the present embodiment, the focus detection area 35 in FIG. 3 extending in the Y-axis direction is a part of three rows in the Y-axis direction as shown in FIG. Further, the focus detection area 36 in FIG. 3 extending in the X-axis direction is a part of three rows in the X-axis direction as shown in FIG.

  FIG. 31 is a schematic plan view schematically showing the main part of the blue pixel 20B3. FIG. 32 is a schematic plan view schematically showing the main part of the blue pixel 20B4. FIG. 33 is a schematic plan view schematically showing the main part of the blue pixel 20B5. FIG. 34 is a schematic plan view schematically showing the main part of the blue pixel 20B6. 31 to 33, the same or corresponding elements as those in FIGS. 13 and 14 are denoted by the same reference numerals, and redundant description thereof is omitted.

  The blue pixel 20B3 basically differs from the blue pixel 20B1 in that the −Y side second focus detection charge accumulation layer 54 (and hence the second focus detection photodiode 43) is removed. Only. The circuit configuration of the blue pixel 20B3 is obtained by removing the second focus detection photodiode 43 and the third transfer transistor 47 in FIG.

  The only difference between the blue pixel 20B4 and the blue pixel 20B1 is that the + Y side first focus detection charge accumulation layer 53 (and hence the first focus detection photodiode 42) is removed. It is. The circuit configuration of the blue pixel 20B4 is the same as that of FIG. 6 except that the first focus detection photodiode 42 and the second transfer transistor 46 are removed.

  The only difference between the blue pixel 20B5 and the blue pixel 20B2 is that the + X side second focus detection charge storage layer 54 (and hence the second focus detection photodiode 43) is removed. It is. The circuit configuration of the blue pixel 20B5 is the same as that of FIG. 6 except that the second focus detection photodiode 43 and the third transfer transistor 47 are removed.

  The blue pixel 20B6 is basically different from the blue pixel 20B2 in that the first focus detection charge storage layer 53 on the -X side (and hence the first focus detection photodiode 42) is removed. Only. The circuit configuration of the blue pixel 20B3 is the same as that of FIG. 6 except that the first focus detection photodiode 42 and the second transfer transistor 46 are removed.

  In the present embodiment, for example, when the focus detection area 35 shown in FIG. 29 is designated, the focus detection signals from all the blue pixels 20B3 in the area 35 and all the blue pixels 20B4 in the area 35 are specified. The defocus amount is calculated using the focus detection signal from. When the focus detection area 36 shown in FIG. 30 is designated, the focus detection signals from all the blue pixels 20B5 in the area 36 and the focus detection signals from all the blue pixels 20B6 in the area 36 are obtained. To calculate the defocus amount.

  In the present embodiment, as necessary, in the blue pixels 20B3, 20B4, 20B5, and 20B6, the focus detection charge storage layer 53 (or 54) in the effective light receiving region of the imaging charge storage layer 52 is used. A blue color filter that selectively transmits only the blue wavelength component is provided at a location corresponding to the non-overlapping region. Further, as in the first embodiment, a separation layer may be provided under the imaging charge storage layer 52. When the separation layer is provided in this way, unnecessary charges are not entered into the image pickup signal and noise does not occur. Further, a P-type well may be provided in an N-type silicon substrate, and the focus detection charge storage layer 53 and the imaging charge storage layer 52 may be disposed therein. In that case, unnecessary charges are absorbed by the N-type silicon, so that no noise is generated.

  Also in this embodiment, the same advantages as those in the first embodiment can be obtained.

  In the present embodiment, blue pixels 20B3 'and 20B4 shown in FIGS. 35 and 36 may be used in place of the blue pixels 20B3 and 20B4. In the blue pixel 20 </ b> B <b> 3 ′, a part of the first focus detection charge accumulation layer 53 on the + Y side is expanded so as to protrude to the −Y side from the optical axis O to some extent. In the blue pixel 20B4 ', a part of the second focus detection charge accumulation layer 54 on the -Y side is expanded so as to protrude to the + Y side from the optical axis O to some extent. The blue pixels 20B5 and 20B6 may be similarly modified. In this case, a larger focus detection signal can be obtained, and the SN ratio of the focus detection signal is improved.

  Modifications similar to those obtained by modifying the first embodiment to obtain the second to fifth embodiments may be applied to the sixth embodiment.

  Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments.

  For example, although the above-described embodiment is an example in which a system using R, G, and B as a combination of colors is employed, the present invention may employ a complementary color system.

  Further, for example, in the first embodiment, the blue pixels 20B1 and 20B2 include one focus detection charge storage layer covering the entire effective light receiving region and two first and second focus detection charge storages. This corresponds to one divided into layers 53 and 54. However, in the present invention, the number of focus detection charge storage layers provided in one pixel is not limited to two. For example, four focus detection charges corresponding to one pixel divided into four equal parts. An accumulation layer may be provided.

  Furthermore, in the present invention, one or more focus detection charge storage layers may be provided for all of the pixels instead of some of the pixels.

  The present invention can also be applied to an amplification type solid-state imaging device using an amplification unit other than a MOS transistor.

1 is a schematic block diagram illustrating an imaging apparatus according to a first embodiment of the present invention. It is a circuit diagram which shows schematic structure of the solid-state image sensor in FIG. It is a schematic plan view which shows typically the solid-state image sensor in FIG. FIG. 4 is a schematic enlarged view in which the vicinity of a predetermined focus detection region in FIG. 3 is enlarged. FIG. 4 is a schematic enlarged view in which the vicinity of another predetermined focus detection region in FIG. 3 is enlarged. It is a circuit diagram which shows the blue pixel of the solid-state image sensor in FIG. It is a schematic plan view which shows typically the main elements of the blue pixel of the solid-state image sensor in FIG. FIG. 2 is a schematic plan view schematically showing some elements of blue pixels of the solid-state imaging device in FIG. 1. FIG. 2 is a schematic plan view schematically showing another part of the blue pixels of the solid-state imaging device in FIG. 1. FIG. 8 is a schematic cross-sectional view along the line A-A ′ in FIG. 7. It is a schematic sectional drawing in alignment with the B-B 'line of FIG. FIG. 8 is a schematic sectional view taken along line C-C ′ in FIG. 7. It is a schematic plan view which shows typically the principal part of the blue pixel of the solid-state image sensor in FIG. It is a schematic plan view which shows typically the principal part of the other blue pixel of the solid-state image sensor in FIG. It is a circuit diagram which shows the red pixel and green pixel of the solid-state image sensor in FIG. It is a schematic sectional drawing which shows the red pixel and green pixel of the solid-state image sensor in FIG. It is a timing chart which shows the drive procedure of the solid-state image sensor in FIG. 1 at the time of focus detection mode. It is a timing chart which shows the drive procedure of the solid-state image sensor in FIG. 1 at the time of imaging mode. 2 is a timing chart showing a driving procedure of the solid-state imaging device in FIG. 1 in a focus detection / imaging simultaneous mode. It is a figure which shows typically pixel arrangement | positioning of the solid-state image sensor of the imaging device by the 2nd Embodiment of this invention. It is a figure which shows typically pixel arrangement | positioning of the solid-state image sensor of the imaging device by the 3rd Embodiment of this invention. It is another figure which shows typically pixel arrangement | positioning of the solid-state image sensor of the imaging device by the 3rd Embodiment of this invention. It is a schematic plan view which shows typically the main elements of the red pixel used in the 3rd Embodiment of this invention. FIG. 24 is a schematic plan view schematically showing some elements of the red pixel shown in FIG. 23. FIG. 24 is a schematic plan view schematically showing another part of the red pixel shown in FIG. 23. FIG. 24 is a schematic cross-sectional view along the line D-D ′ in FIG. 23. It is a figure which shows typically pixel arrangement | positioning of the solid-state image sensor of the imaging device by the 4th Embodiment of this invention. It is a figure which shows typically the pixel arrangement | positioning of the solid-state image sensor of the imaging device by the 5th Embodiment of this invention. It is a figure which shows typically the pixel arrangement | positioning of the solid-state image sensor of the imaging device by the 6th Embodiment of this invention. It is another figure which shows typically pixel arrangement | positioning of the solid-state image sensor of the imaging device by the 6th Embodiment of this invention. It is a schematic plan view which shows typically the principal part of the blue pixel used in the 6th Embodiment of this invention. It is a schematic plan view which shows typically the principal part of the other blue pixel used in the 6th Embodiment of this invention. It is a schematic plan view which shows typically the principal part of the other blue pixel used by the 6th Embodiment of this invention. It is a schematic plan view which shows typically the principal part of the other blue pixel used by the 6th Embodiment of this invention. It is a schematic plan view which shows the modification of a blue pixel. It is a schematic plan view which shows the modification of another blue pixel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electronic camera 2 Imaging lens 3 Solid-state image sensor 20 20R, 20G, 20B1-20B6, 20R1, 20R2, 20G1, 20G2 Pixel 41 Photodiode for imaging 42, 43 Photodiode for focus detection 52 Charge storage layer for imaging 53, 54 Focus Charge storage layer for detection

Claims (17)

A solid-state imaging device that photoelectrically converts a subject image formed by an optical system,
A plurality of pixels that are arranged two-dimensionally and each output an imaging signal for forming an image signal indicating the subject image;
Each one pixel of the plurality of pixels has an imaging photoelectric conversion unit that mainly photoelectrically converts a predetermined wavelength component of incident light to obtain a charge to be the imaging signal,
At least some of the plurality of pixels can output a plurality of focus detection signals for detecting a focus adjustment state of the optical system independently of each other in addition to the imaging signal. Configured,
In addition to the imaging photoelectric conversion unit of the pixel, each of the at least some of the pixels has at least a part of the imaging photoelectric of the pixel when viewed from the incident direction of the incident light. A plurality of focus detection photoelectric conversion units arranged so as to overlap with the conversion unit, the wavelength component being substantially different from the predetermined wavelength component of the incident light that is photoelectrically converted by the imaging photoelectric conversion unit of the pixel Each having a plurality of focus detection photoelectric conversion units that respectively obtain photoelectric charges to be converted into the plurality of focus detection signals.
The plurality of focus detection photoelectric conversion units of each one of the at least some pixels respectively select light beams from the exit pupil regions that are decentered in different directions from the center of the exit pupil of the optical system. Received light and photoelectrically converted,
A solid-state imaging device.   For each one pixel of the at least some pixels, the predetermined wavelength component of the incident light that is mainly photoelectrically converted by the imaging photoelectric conversion unit of the pixel, and the focus detection photoelectric conversion unit of the pixel 2. The solid-state image pickup device according to claim 1, wherein the wavelength component of the incident light mainly subjected to photoelectric conversion is a visible wavelength component. The number of the plurality of focus detection photoelectric conversion units in each one of the at least some pixels is two;
One focus detection photoelectric conversion unit among the plurality of focus detection photoelectric conversion units of each one pixel of the at least some of the pixels is the exit decentered in a predetermined direction from the center of the exit pupil of the optical system. Selectively receiving and photoelectrically converting the light flux from the first region of the pupil;
The other imaging photoelectric conversion unit among the plurality of focus detection photoelectric conversion units of each one of the at least some pixels is in a direction opposite to the predetermined direction from the center of the exit pupil of the optical system. Selectively receiving and photoelectrically converting a light beam from the second region of the exit pupil that is eccentric to
The solid-state imaging device according to claim 1 or 2. The imaging photoelectric conversion unit of at least one of the at least some pixels is arranged in a first semiconductor layer of a first conductivity type and stores the charge to be the imaging signal. Type charge storage layer for imaging,
Each of the focus detection photoelectric conversion units of the at least one pixel has at least a part of the imaging charge of the pixel through a part of the first semiconductor layer when viewed from the incident direction of the incident light. A second-conductivity-type focus detection that is arranged in the first semiconductor layer so as to overlap the storage layer and stores the electric charge to be one focus detection signal among the plurality of focus detection signals of the pixel. The solid-state imaging device according to claim 1, further comprising a charge storage layer.   In the at least one pixel, the first conductivity type layer having an impurity concentration higher than that of the first semiconductor layer is interposed between the imaging charge storage layer and each focus detection charge storage layer. The solid-state imaging device according to claim 4, wherein the solid-state imaging device is disposed in the first semiconductor layer so as to be positioned.   The at least one pixel among the at least some pixels, wherein the plurality of focus detection photoelectric conversion units of the pixel photoelectrically convert substantially the same wavelength component of the incident light. The solid-state imaging device according to any one of 1 to 5.   With respect to at least one of the at least some pixels, the predetermined wavelength component of the incident light that is mainly photoelectrically converted by the imaging photoelectric conversion unit of the pixel is mainly the focus detection photoelectric conversion unit of the pixel. The solid-state imaging device according to claim 1, wherein the solid-state imaging device has a wavelength component shorter than a wavelength component of the incident light to be photoelectrically converted.   With respect to at least one of the at least some pixels, the predetermined wavelength component of the incident light that is mainly photoelectrically converted by the imaging photoelectric conversion unit of the pixel is mainly the focus detection photoelectric conversion unit of the pixel. The solid-state imaging device according to claim 1, wherein the solid-state imaging device has a wavelength component longer than a wavelength component of the incident light to be photoelectrically converted.   Each one of the at least some pixels is provided in a one-to-one relationship with the pixel, and the microlens guides incident light to the imaging photoelectric conversion unit and the plurality of focus detection photoelectric conversion units of the pixel. The solid-state imaging device according to claim 1, wherein A solid-state imaging device that photoelectrically converts a subject image formed by an optical system,
A plurality of pixels that are arranged two-dimensionally and each output an imaging signal for forming an image signal indicating the subject image;
Each one pixel of the plurality of pixels has an imaging photoelectric conversion unit that mainly photoelectrically converts a predetermined wavelength component of incident light to obtain a charge to be the imaging signal,
At least some of the plurality of pixels are configured to independently output a focus detection signal for detecting a focus adjustment state of the optical system, in addition to the imaging signal.
In addition to the imaging photoelectric conversion unit of the pixel, each of the at least some of the pixels includes at least a part of the imaging photoelectric conversion unit of the pixel when viewed from the incident direction of the incident light. A photoelectric conversion unit for focus detection arranged so as to overlap with the photoelectric conversion unit, which mainly converts a wavelength component substantially different from the predetermined wavelength component of the incident light that is photoelectrically converted by the imaging photoelectric conversion unit of the pixel. A focus detection photoelectric conversion unit for obtaining a charge to be the focus detection signal
The focus detection photoelectric conversion unit of some of the at least some pixels selects a light beam from the first region of the exit pupil that is decentered in a predetermined direction from the center of the exit pupil of the optical system. Received light and photoelectrically converted,
The focus detection photoelectric conversion unit of another part of the at least some of the pixels includes a first part of the exit pupil that is decentered in a direction opposite to the predetermined direction from the center of the exit pupil of the optical system. Selectively receiving light from the region 2 and photoelectrically converting it;
A solid-state imaging device.   For each one of the at least some pixels, the predetermined wavelength component of the incident light that is mainly photoelectrically converted by the imaging photoelectric conversion unit of the pixel, and the focus detection photoelectric conversion unit of the pixel are mainly The solid-state imaging device according to claim 10, wherein the wavelength component of the incident light to be photoelectrically converted is a wavelength component in a visible range. The imaging photoelectric conversion unit of at least one of the at least some pixels is arranged in a first semiconductor layer of a first conductivity type and stores the charge to be the imaging signal. Type charge storage layer for imaging,
The focus detection photoelectric conversion unit of the at least one pixel is at least partly stored in the pixel through the first semiconductor layer when viewed from the incident direction of the incident light. 2. A focus detection charge storage layer of a second conductivity type, which is disposed on the first semiconductor layer so as to overlap with the layer and stores the charge to be the focus detection signal of the pixel. Item 12. The solid-state imaging device according to Item 10 or 11.   In the at least one pixel, the first conductivity type layer having an impurity concentration higher than that of the first semiconductor layer is positioned between the imaging charge storage layer and the focus detection charge storage layer. The solid-state imaging device according to claim 12, wherein the solid-state imaging device is arranged in the first semiconductor layer. The plurality of pixels are divided into a plurality of groups,
The predetermined wavelength components of the incident light that are mainly photoelectrically converted by the imaging photoelectric conversion units of the pixels of the same group are substantially the same,
The predetermined wavelength components of the incident light that are mainly photoelectrically converted by the imaging photoelectric conversion units of the pixels of different groups are substantially different from each other;
The solid-state imaging device according to claim 1, wherein the solid-state imaging device is provided.   The solid-state imaging device according to claim 14, wherein the at least some of the pixels do not have a color filter. The plurality of pixels include pixels other than the at least some of the pixels,
The pixels other than the at least some pixels have a color filter.
The solid-state imaging device according to claim 14 or 15,   17. A detection processing unit that outputs a detection signal indicating a focus adjustment state of the optical system based on the solid-state imaging device according to claim 1 and the focus detection signal from the at least some pixels. An imaging apparatus comprising:

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