JP2012049201A - Imaging element and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging element that can be easily manufactured regardless of a rear face irradiation type or a front face irradiation type, and that has a pupil division function that shortens a photographing time to enable high picture quality photographing.SOLUTION: Cross sections of pupil division pixel parts 10 and 11 in a silicon substrate are laterally inverted. The pixel part 10 has: an electric charge generation region 17; a charge storage region 13 provided on the electric charge generation region 17; a barrier region 16 contacted only with the electric charge generation region 17 among the electric charge generation region 17 and the charge storage region 13, and that forms a potential barrier to the electric charge generation region 17; and an electric charge discharge region 15 provided between the barrier region 16 and the silicon substrate surface. The barrier region 16 is provided at a right edge in the pixel part 10 and provided at a left edge in the pixel part 11. A wire 30 for voltage application is connected to the barrier region 16.

Description

  The present invention relates to an imaging element, an imaging apparatus, and an imaging method.

  A phase difference detection method is known as one of focus detection techniques. In this method, a pair of pupil division pixels that receive light beams that pass through different pupil regions of the photographing lens are provided, and the defocus amount of the photographing lens is detected by using signals from the pair of pupil division pixels. Is. According to this phase difference detection method, focus adjustment can be performed at a higher speed than the focus detection technology of the contrast AF method. As imaging devices to which the principle of such a phase difference detection method is applied, those described in Patent Documents 1 and 2 are known.

  The solid-state imaging device described in Patent Document 1 forms a pair of pupil division pixels by dividing a photoelectric conversion region below one microlens into two. However, in this configuration, the smaller the size, the more difficult the manufacture becomes, and color mixing tends to occur, resulting in lack of phase difference detection accuracy. Moreover, it lacks toughness with respect to various incident angles.

  Patent Document 2 describes a solid-state image sensor in which pupil dividing pixels are formed by decentering a light shielding film opening provided above a photoelectric conversion element. However, this configuration is based on the premise that there is a light shielding film above the photoelectric conversion element, and a back-illuminated imaging element that does not require a light shielding film above the photoelectric conversion element (see, for example, Patent Documents 3 and 4). ) Etc. cannot be easily applied.

  In addition, in the solid-state imaging devices described in Patent Documents 1 and 2, since the signal obtained from the pupil division pixel is insufficient in sensitivity, the signal obtained from the pupil division pixel is used when shooting for recording. It is necessary to perform defect correction processing for interpolating the signal with surrounding signals. For this reason, there is a possibility of generation of false colors, and it is difficult to obtain a high-quality image. In addition, the time required for capturing the captured image data (photographing time) is increased by performing the computation for generating the signal by interpolation, and there is a possibility that a photo opportunity will be missed.

  To enable high-quality and high-speed shooting, it is ideal to use the same structure for pupil division pixels and normal shooting pixels so that defect correction processing is not required. Can not do.

JP 2007-281296 A JP 2008-312073 A Japanese Patent Laid-Open No. 2005-20024 JP 2008-103668 A

  The present invention has been made in view of the above circumstances, and can be easily manufactured regardless of the back-illuminated type or the front-illuminated type, and can perform high-quality imaging by shortening the imaging time. An object of the present invention is to provide an imaging device having a pupil division function, an imaging device including the imaging device, and an imaging method using the imaging device.

  The image sensor of the present invention is an image sensor having a plurality of pairs of pixel parts for pupil division, and each of the two pixel parts constituting the pair is formed in a semiconductor substrate and generates a charge. Type charge generation region and charge accumulation of the first conductivity type that is formed in contact with the charge generation region in the semiconductor substrate and has a higher impurity concentration than the charge generation region that accumulates the charge generated in the charge generation region A barrier region of the opposite conductivity type to the first conductivity type formed in contact with only the charge generation region among the charge storage region and the charge generation region, and the barrier region adjacent to the barrier region. A portion where the charge generation region of one of the two pixel portions constituting the pair is in contact with the barrier region is divided into pupils rather than the center of the charge generation region. One side of direction There, the portion where the charge generation region of the other pixel of the two pixel portions constituting the pair is in contact with the barrier regions are those on the other side of the pupil division direction of the center of the charge-generation region.

  According to this configuration, when the potential barrier formed in the barrier region is extinguished, the charge generated near the portion in contact with the barrier region of the charge generation region moves to the charge discharge region, and the charge generation region The charge generated in the portion not in contact with the barrier region moves to the charge accumulation region. Since the positions of the portions where the charge generation regions of the two pixel portions constituting the pair are in contact with the barrier region are opposite to each other in the pupil division direction, the portions move to the charge discharge regions of the two pixel portions constituting the pair. The charge can be a charge corresponding to light that has passed through different pupil regions. As a result, the charge storage regions of the two pixel portions constituting the pair can store charges corresponding to light that has passed through different pupil regions, and pupil division is possible.

  In the pupil division methods described in Patent Documents 1 and 2, it is necessary to interpolate and generate signals obtained from the pupil division pixels from the surroundings when photographing. On the other hand, according to the above-described configuration, it is possible to cause the two pixel portions of the pair to function as a pixel portion for photographing by performing photographing in a state where a potential barrier is formed. For this reason, arithmetic processing for signal interpolation becomes unnecessary, and high image quality and a reduction in photographing time can be achieved. In addition, according to the above configuration, the aperture is optically narrowed so that pupil division is not performed. Therefore, even when applied to a back-illuminated image sensor, high sensitivity, which is the greatest advantage of the back-illuminated image sensor, is impaired. There is nothing. In addition, since it is not necessary to add a process for forming a light-shielding film or the like, it is possible to prevent an increase in manufacturing cost, color mixing, and the like. Moreover, it can respond easily to miniaturization.

  The imaging apparatus according to the present invention includes a first imaging process that performs imaging in a state where a potential barrier with respect to the charge generation region is formed by the barrier region, the focus lens disposed in front of the imaging device, and the barrier region. A drive unit that switches between a second imaging process that performs imaging in a state where the potential barrier is eliminated, and a position of the focus lens based on a captured image signal obtained by provisional imaging with the imaging element A focus adjustment unit that performs a focus adjustment process, and the focus adjustment process performs phase adjustment by a phase difference detection method based on a captured image signal obtained from the image sensor in the second imaging process. Including the AF process, the driving unit performs the first imaging process at the time of the main photographing performed after the focus adjustment process.

  The imaging method of the present invention is an imaging method using the imaging device, wherein a first imaging process that performs imaging in a state where a potential barrier with respect to the charge generation region is formed by the barrier region, and the potential barrier disappears. A driving step for switching between the second photographing process for photographing in a state of being performed and a position of a focus lens disposed in front of the image sensor based on a captured image signal obtained by provisional photographing with the image sensor A focus adjustment step of performing a focus adjustment process for adjusting the focus, and the focus adjustment process performs focus adjustment by a phase difference detection method based on a captured image signal obtained from the image sensor in the second imaging process. Including the phase difference AF process, the driving step performs the first imaging process during the main imaging performed after the focus adjustment process.

  According to the present invention, an imaging device having a pupil division function that can be easily manufactured regardless of the back-side illumination type and the front-side illumination type, and that can perform high-quality imaging by shortening the imaging time, An imaging apparatus provided with this, and an imaging method using the same can be provided.

1 is a functional block diagram of an imaging apparatus for explaining an embodiment of the present invention. FIG. 1 is a schematic plan view showing a schematic configuration of an image sensor in the imaging apparatus shown in FIG. AA line cross-sectional schematic diagram of one pair of pixel portions for pupil division in the image sensor shown in FIG. FIG. 2 is an enlarged schematic plan view of the two pixel portions of the pair shown in FIG. The figure which showed the potential distribution in the silicon substrate of the pixel part in the low level state of the image pick-up element shown in FIG. The figure which showed the potential distribution in the silicon substrate of the pixel part in the high level state of the image pick-up element shown in FIG. The figure for demonstrating the pupil division | segmentation principle of the image pick-up element shown in FIG. Flowchart for explaining the shooting operation of the imaging apparatus shown in FIG. Timing chart for explaining the shooting operation of the imaging apparatus shown in FIG. Flowchart for explaining photographing operation when 3D photographing mode is installed in the image pickup apparatus shown in FIG. The figure which shows the 1st modification of the image pick-up element mounted in the imaging device shown in FIG. The figure which shows the 2nd modification of the image pick-up element mounted in the imaging device shown in FIG. The figure which showed the state when the high level voltage which eliminates the potential barrier formed of the barrier area | region 16 is applied to the electric charge discharge area | region 15a of the pixel parts 10 and 11 shown in FIG. The figure which shows the 3rd modification of the image pick-up element mounted in the imaging device shown in FIG. BB cross-sectional schematic diagram of FIG. CC cross-sectional schematic diagram of FIG. DD cross-sectional schematic diagram of FIG. The figure which shows the 4th modification of the image pick-up element mounted in the imaging device shown in FIG. The figure which shows the 5th modification of the image pick-up element mounted in the imaging device shown in FIG. The figure which shows the 6th modification of the image pick-up element mounted in the imaging device shown in FIG. The figure which shows the 7th modification of the image pick-up element mounted in the imaging device shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a functional block diagram of an imaging apparatus 100 for explaining an embodiment of the present invention. The imaging system of the imaging apparatus 100 includes a photographic lens system 41, a diaphragm 42, a mechanical shutter 43, an imaging element 44, and an analog / digital (AD) conversion unit 45.

  The imaging device 44 is a so-called back-illuminated image sensor, which receives light from one surface (back surface) of a silicon substrate (Si substrate) as a semiconductor substrate, and charges generated in the silicon substrate in response to the light. Reading is performed using a reading circuit formed on the other surface (front surface) of the silicon substrate. As the readout circuit, either a CCD circuit composed of a CCD (Charge Coupled Device) and an amplifier or a MOS circuit composed of a MOS (Metal-Oxide-Semiconductor) transistor may be used. The case where it employ | adopts is demonstrated.

  A diaphragm 42 is disposed behind the photographing lens system 41, and the photographing lens system 41 and the diaphragm 42 constitute a photographing optical system.

  A CMOS-type and back-illuminated imaging element 44, which will be described in detail later, is disposed on the back of the diaphragm 42. A mechanical shutter 43 is disposed between the diaphragm 42 and the image sensor 44. A captured image signal corresponding to the subject light image that has entered the light receiving surface of the image sensor 44 through the photographing lens system 41, the aperture 42, and the mechanical shutter 43 in this order is converted into digital data by the AD converter 45, and the bus 56 Is output.

  The bus 56 includes a central control unit (CPU) 46 that performs overall control of the entire imaging apparatus 100, an operation unit 48 including operation buttons including a shutter button, a DSP, and the like, based on instructions from the CPU 46. An image processing unit 49 that performs known image processing on the captured image signal, a video encoder 50 that converts captured image data obtained by image processing of the captured image signal into display data, and a video encoder 50 A driver 53 that displays the converted captured image data on the display unit 52, a memory 51, and a media control unit 54 are connected. A recording medium (memory card) 55 is detachably attached to the media control unit 54.

  A device control unit 47 is connected to the CPU 46. The device control unit 47 performs drive control of the image sensor 44 according to an instruction from the CPU 46, performs aperture amount adjustment control of the diaphragm 42, performs position control of the focus lens of the photographing lens system 41 and position control of the zoom lens, Open / close control of the mechanical shutter 43 is performed.

  FIG. 2 is a schematic plan view showing a schematic configuration of the image pickup device 44 in the image pickup apparatus 100 shown in FIG. FIG. 2 shows a view of the image sensor 44 as viewed from the surface side of the silicon substrate.

  As shown in FIG. 2, the imaging element 44 includes a first group including a plurality of pixel units 10 (thin line blocks) and a second group including a plurality of pixel units 11 (thick line blocks). All the pixel portions included in the imaging element 44 are arranged in a two-dimensional manner (in the example of FIG. 2, a square lattice shape) in the row direction X and the column direction Y orthogonal thereto. The pixel portion in the even-numbered column from the left is the pixel portion 11.

  Each pixel unit 10 and a pixel unit 11 adjacent to each pixel unit 10 in the same direction (in the example of FIG. 2, the pixel unit 11 on the right side of each pixel unit 10) are different pupil regions of the imaging optical system. A pair of pupil-dividing pixel portions that receive a light beam that passes through is formed. It can also be said that the image pickup element 44 is a plurality of two-dimensionally arranged pairs.

  FIG. 3 is a schematic cross-sectional view taken along the line AA of the pair of pixel portions for pupil division in the image sensor 44 shown in FIG.

  A charge generation region 17 is formed on the back side in the silicon substrate of the pixel unit 10. The charge generation region 17 is a region formed of an N-type impurity layer that generates a charge corresponding to light incident from the back side of the silicon substrate.

  A charge accumulation region 13 is formed in contact with the charge generation region 17 on the surface side of the silicon substrate relative to the charge generation region 17 in the silicon substrate of the pixel unit 10. The charge storage region 13 generates a charge corresponding to light incident from the back side of the silicon substrate, and stores a charge generated in the charge generation region 17 and the charge storage region 13 itself. The charge accumulation region 13 is a region made of an N-type impurity layer having an impurity concentration higher than that of the charge generation region 17. The charge generation region 17 and the charge storage region 13 constitute a photoelectric conversion region (photodiode) of the pixel unit 10.

  In the example of FIG. 3, the charge generation region 17 is formed from end to end in the row direction X of the pixel portion 10, and the charge accumulation region 13 is smaller in width in the row direction X than the charge generation region 17. In addition, the center in the row direction X is decentered leftward with respect to the center in the row direction X of the charge generation region 17.

  Between the charge storage region 13 in the silicon substrate of the pixel unit 10 and the silicon substrate surface, a surface P region 12 made of a P-type impurity layer for suppressing dark current generation in the charge storage region 13 is formed. ing.

  A barrier region 16 is formed in contact with the charge generation region 17 on the surface side of the silicon substrate from the charge generation region 17 in the silicon substrate of the pixel unit 10. The barrier region 16 is a region made of a P-type impurity layer that forms a potential barrier with respect to the charge generation region 17. The portion of the barrier region 16 that is in contact with the charge generation region 17 is located on one side (right side) of the pupil generation direction (row direction X) from the center of the charge generation region 17 in the row direction X. In other words, the barrier region 16 is formed in contact with one end portion (the right end portion in the example of FIG. 3) of the end portions in the row direction X of the charge generation region 17.

  Between the barrier region 16 in the silicon substrate of the pixel portion 10 and the silicon substrate surface, a charge discharge region 15 made of an N-type impurity layer having the same conductivity type as the charge generation region 17 is formed. In the example of FIG. 3, the charge discharge region 15 is a region having a higher impurity concentration than the charge storage region 13. A wiring 30 formed above the surface of the silicon substrate is electrically connected to the charge discharge region 15, and this wiring 30 is connected to the device control unit 47 shown in FIG.

  An element isolation composed of a P-type impurity layer having an impurity concentration higher than that of the barrier region 16 is provided between the surface P region 12 and the charge storage region 13 in the silicon substrate of the pixel unit 10, and the barrier region 16 and the charge discharge region 15. Region 14 is formed. The element isolation region 14 separates the surface P region 12 and the charge storage region 13 from the barrier region 16 and the charge discharge region 15.

  Since the cross-sectional shape of the pixel unit 11 is merely an inversion of the cross-sectional shape of the pixel unit 10 in the pupil division direction (row direction X), it is the same as the pixel unit 10 in an area having the same function. The reference numerals are attached and the description is omitted.

  Between the pixel portion 10 and the pixel portion 11 in the silicon substrate, an element isolation region 18 made of a P-type impurity layer for separating the pixel portions is formed. Further, a back surface P region 19 made of a high concentration P-type impurity layer is formed between the charge generation region 17 of the pixel portions 10 and 11 and the back surface of the silicon substrate.

  FIG. 4 is an enlarged schematic plan view of two pixel portions constituting the pair shown in FIG.

  A floating diffusion FD is formed next to the surface P region 12 on the silicon substrate surface of the pixel unit 10. A transfer gate electrode 31 is formed above the silicon substrate between the floating diffusion FD and the surface P region 12 via an insulating film (not shown). When a high voltage is applied to the transfer gate electrode 31, charges accumulated in the charge accumulation region 13 are transferred to the floating diffusion FD.

  A drain region 27 is formed on the right side of the floating diffusion FD. A wiring 25 is connected to the drain region 27, and the power supply voltage VDD is supplied to the wiring 25. A reset gate electrode 21 is formed above the silicon substrate between the floating diffusion FD and the drain region 27 via an insulating film (not shown). When a high voltage is applied to the reset gate electrode 21, the charge of the floating diffusion FD is discharged to the drain region 27, and the floating diffusion FD is reset. The floating diffusion FD, the reset gate electrode 21, and the drain region 27 constitute a reset transistor that resets the charge of the floating diffusion FD.

  A source region 28 is formed on the right side of the drain region 27. A gate electrode 22 is formed above the silicon substrate between the drain region 27 and the source region 28 via an insulating film (not shown). A wiring 24 is connected to the gate electrode 22, and the wiring 24 is electrically connected to the floating diffusion FD. The drain region 27, the gate electrode 22, and the source region 28 constitute an output transistor that outputs a signal corresponding to the potential of the floating diffusion FD.

  A drain region 29 is formed on the right side of the source region 28. A gate electrode 23 is formed above the silicon substrate between the source region 28 and the drain region 29 via an insulating film (not shown). A signal output line 26 is connected to the drain region 29. The source region 28, the gate electrode 23, and the drain region 29 constitute a selection transistor that selectively outputs an output signal from the output transistor to the signal output line 26. When the selection transistor is turned on, an output signal from the output transistor can be output to the signal output line 26.

  As described above, in the pixel portion 10, a well-known MOS circuit (a MOS circuit including a floating diffusion FD and three transistors in the example of FIG. 3) is formed as a readout circuit on the surface side of the silicon substrate. Note that the configuration of the readout circuit of the pixel unit 11 is merely the left-right inversion of the configuration of the pixel unit 10, and thus description thereof is omitted. The layout of this readout circuit is an example, and a well-known MOS circuit can be formed using a vacant space on the silicon substrate surface side.

  Next, the principle of pupil division of the pixel units 10 and 11 for pupil division configured as described above will be described.

  In the imaging apparatus 100, the device control unit 47 controls the voltage supplied to the wiring 30 connected to the charge discharging region 15, thereby causing the pixel units 10 and 11 to function as a pupil division pixel unit or a pupil division function. Or function as a pixel portion for normal photography without the. Specifically, the device control unit 47 supplies the voltage supplied to the wiring 30 connected to the charge discharging region 15, the high level voltage that can eliminate the potential barrier formed by the barrier region 16, and the potential. Switching is made with a low-level voltage that can be formed without eliminating the barrier. Hereinafter, a state where a low level voltage is applied to the charge discharging region 15 is referred to as a low level state, and a state where a high level voltage is applied to the charge discharging region 15 is referred to as a high level state.

  FIG. 5 is a diagram showing a potential distribution in the silicon substrate of the pixel unit 10 in the low level state. 5, FIG. 5A is a cross-sectional potential diagram along line BB in the cross-sectional view shown in FIG. 3, and FIG. 5B is a cross-sectional potential diagram along line CC in the cross-sectional view shown in FIG. FIG. 6 is a diagram showing the potential distribution in the silicon substrate of the pixel unit 10 in the high level state. 6, FIG. 6A is a cross-sectional potential diagram along line BB in the cross-sectional view shown in FIG. 3, and FIG. 6B is a cross-sectional potential diagram along line CC in the cross-sectional view shown in FIG.

  In the low level state, as shown in FIG. 5B, the potential of the barrier region 16 functions as a barrier against the charge generation region 17. Therefore, the charge generated in the vicinity of the portion of the charge generation region 17 in contact with the barrier region 16 moves to the potential well formed by the charge storage region 13 shown in FIG. 5A without exceeding this barrier. That is, in the low level state, all charges generated in the charge generation region 17 are accumulated in the charge accumulation region 13.

  On the other hand, in the high level state, as shown in FIG. 6B, the potential barrier formed by the barrier region 16 disappears, and the potential of the barrier region 16 does not function as a barrier for the charge generation region 17. For this reason, the charge generated in the vicinity of the portion in contact with the barrier region 16 in the charge generation region 17 moves to the charge discharge region 15 through the barrier region 16 and is not accumulated in the charge accumulation region 13. On the other hand, the charge generated in the portion not in contact with the barrier region 16 in the charge generation region 17 moves to the potential well formed by the charge storage region 13 shown in FIG. 6A. That is, in the high level state, out of the charges generated in the charge generation region 17, only charges other than those generated at the right end in the row direction X of the charge generation region 17 are stored in the charge storage region 13.

  Up to this point, the pixel unit 10 has been described. However, since the pixel unit 11 has a horizontally inverted structure with respect to the pixel unit 10, among the charges generated in the charge generation region 17 in the high level state, Only charges other than those generated at the left end in the row direction X of the charge generation region 17 are stored in the charge storage region 13, and in the low level state, all charges generated in the charge generation region 17 are stored in the charge storage region 13. Will be.

  As described above, in the high level state, the pixel component 10 and the pixel unit 11 have different charge components accumulated in the charge accumulation region 13. As a result, pupil division is possible between the pixel unit 10 and the pixel unit 11. The principle of pupil division will be further described with reference to FIG.

  FIG. 7A in FIG. 7 is a diagram for explaining the movement of charges in the pixel unit 10 in the low level state. FIG. 7B in FIG. 7 is a diagram for explaining the movement of charges in the pixel unit 10 in the high level state.

  The light incident on the pixel unit 10 from the back side of the silicon substrate includes a component incident on the pixel unit 10 from the left side and a component incident from the right side. As shown in FIG. 7A, the light component incident from the left side is incident on the right end of the charge generation region 17 and generates a charge (the one in which − is entered in a circle). Conversely, the light component incident from the right side is incident on the left end of the charge generation region 17 and generates charges here.

  In the low level state, since the barrier region 16 forms a potential barrier with respect to the charge generation region 17, all charges generated in the charge generation region 17 move to the charge storage region 13 as indicated by arrows in FIG. 7A. And accumulate here.

  On the other hand, in the high level state, as shown in FIG. 7B, the potential barrier of the barrier region 16 disappears, and the depletion layer spreads from the charge discharge region 15 as shown by the hatched portion, so that it depends on the light component incident from the left side. The charges move to the charge discharge region 15 through the depletion layer, and the charges corresponding to the light component incident from the right side move to the charge accumulation region 13 and are accumulated.

  The flow of electric charges for the pixel portion 11 is the result of horizontally inverting FIG.

  Therefore, in the high level state, the pixel unit 10 mainly accumulates charges corresponding to the light component incident from the right side, and the pixel unit 11 mainly stores charges corresponding to the light component incident from the left side. accumulate. As a result, the pupil division can be performed only by electrical control of changing the voltage applied to the wiring 30 without changing the optical path of the light incident on the pixel unit 10 and the pixel unit 11 at all. it can. The pixel unit 10 and the pixel unit 11 can be realized mainly by changing the structure in the silicon substrate with respect to the conventional back-illuminated image sensor. For this reason, as described in Patent Documents 1 and 2, the sensitivity is reduced as compared with the case where the configuration of the element optical system (microlens or light shielding film) outside the silicon substrate is changed to make the pixel division pixel section. There are advantages such as being able to prevent, being able to easily cope with miniaturization, and preventing an increase in manufacturing cost.

  In the high level state, if the charge generated in the region other than the hatched portion of FIG. 7B of the charge generation region 17 positively flows into the charge discharge region 15, the pupil division performance deteriorates. For this reason, in the high level state, the charge generation region 17 and the charge accumulation are performed so that the charge generated in the portion not in contact with the barrier region 16 of the charge generation region 17 of the pixel portion 10 actively moves to the charge accumulation region 13. The concentration of the region 13 and the barrier region 16 is preferably determined. For example, as shown in FIG. 6, in the high level state, the potential gradient from the charge generation region 17 to the charge storage region 13 is larger than the potential gradient from the charge generation region 17 to the barrier region 16. It is preferable to set the density of each region.

  The above-described pupil division method is particularly excellent in that the pupil division is not performed in the pixel unit 10 and the pixel unit 11 in the low level state, so that the pupil division pixel unit is a normal imaging pixel. It can be used as a part. For this reason, the imaging apparatus 100 performs the main imaging in the low level state at the time of the main imaging for recording the captured image data, and completely eliminates the defect correction processing of the signal of the pixel division pixel section that has been performed conventionally. . Hereinafter, an operation at the time of shooting of the imaging apparatus 100 will be described.

  FIG. 8 is a flowchart for explaining the photographing operation of the imaging apparatus 100 shown in FIG. FIG. 9 is a timing chart for explaining the photographing operation of the imaging apparatus 100 shown in FIG. The device control unit 47 applies a low level voltage to the charge discharge region 15 when the photographing mode is set.

  When the shooting mode is set, the CPU 46 opens the mechanical shutter 43 via the device control unit 47 and starts moving image shooting for live view image display (MV in FIG. 9) by the image sensor 44. When the shutter button included in the operation unit 48 is half-pressed (step S1: YES), the CPU 46 acquires the captured image signal output from the image sensor 44 when the shutter button is half-pressed, and this captured image signal. The exposure value (EV value) is calculated based on the above (step S2, “AE” in FIG. 9).

  Next, the CPU 46 determines whether or not the calculated EV value is greater than or equal to the threshold th (step S3). If the determination result is NO, the process of step S4 is performed, and the determination result is YES. In that case, the process of step S5 is performed.

  In step S4, the CPU 46 performs focus adjustment processing by a contrast detection method via the device control unit 47 by a known method (“AF” in FIG. 9). Specifically, provisional photographing for focus adjustment is performed while moving the focus lens of the photographing lens system 41, and focus adjustment is performed with the focus lens position when the contrast value reaches a peak as the in-focus position.

  In step S <b> 5, the CPU 46 changes the voltage applied to the charge discharge region 15 from the low level to the high level via the device control unit 47.

  After step S5, the CPU 46 performs provisional imaging for focus adjustment by the image sensor 44, and performs focus adjustment by a known phase difference detection method based on the captured image signal output from the image sensor 44 by the provisional imaging. (Step S6, “AF” in FIG. 9). Specifically, the phase difference is detected by comparing the captured image signals obtained from all the pixel units 10 of the image sensor 44 and the captured image signals obtained from all the pixel units 11 of the image sensor 44. The distance to the subject is measured based on the phase difference, the in-focus position is determined, and the focus is adjusted.

  When focus adjustment is performed by the phase difference detection method, the captured image signals obtained from all the pixel units 10 of the image sensor 44 and the captured image signals obtained from all the pixel units 11 of the image sensor 44 are used. It is not always necessary to use it. For example, a captured image signal obtained from all the pixel units 10 in a specific region (for example, a region specified by the user, a region where a face is detected, a predetermined region, etc.) of the image sensor 44 is in the specific region. Phase difference detection may be performed by comparison with captured image signals obtained from all the pixel units 11.

  In this case, it is not necessary to set all the pixel units 10 and 11 to the high level state at the time of provisional imaging, and only the pixel units 10 and 11 that output the imaging signal used for the phase difference detection are set to the high level state, and other pixels. Although it can be considered that the portions 10 and 11 are in a low level state, it is preferable to perform provisional photographing with all the pixel portions 10 and 11 in a high level state. By doing so, it is not necessary to form the wiring 30 for enabling the voltage of the impurity region 15 to be controlled independently for each pixel portion, and the design is facilitated.

  When the calculation of the in-focus position by the phase difference detection method is completed in step S6, the CPU 46 changes the voltage applied to the charge discharge region 15 from the high level to the low level via the device control unit 47 (step S7).

  When the processing of steps S4 and S7 is completed and the shutter button is fully pressed during a predetermined period (step S8: YES), the CPU 46 and the focus determined in step S4 or step S6 are matched with the EV value calculated in step S2. According to the photographing conditions such as the position, the photographing is performed by the image sensor 44 (step S9, “exposure” in FIG. 9). If the shutter button is not fully pressed during the certain period (step S8: NO), the CPU 46 returns to step S2 and calculates the EV value again.

  When the set exposure time has elapsed after execution of the main shooting, the CPU 46 closes the mechanical shutter 43 and ends the main shooting. After the main photographing is completed, imaging signals are output from all the pixel units of the imaging element 44 (“read” in FIG. 9), and the image processing unit 49 applies the captured image signals that are a set of all the imaging signals. Image processing is performed to generate one captured image data. This image processing does not include the defect correction processing that accompanies a reduction in sensitivity of the pixel portion for pupil division that has been performed conventionally. The generated captured image data is previewed on the display unit 52 and recorded on the memory card 55.

  As described above, according to the imaging apparatus 100, since the imaging element 44 is mounted, it is possible to easily switch between imaging with pupil division and imaging without pupil division by electrical control. . For this reason, at the time of provisional imaging for performing focus adjustment, it is possible to perform phase difference detection processing by imaging with pupil division, to perform focus adjustment at high speed, and to obtain captured image data for recording At the time of actual photographing, it is possible to obtain a picked-up image signal that does not require defect correction by photographing without pupil division, and to shorten the time until the photographing process is completed. As a result, it is possible to improve the image quality by eliminating the defect correction process, and it is possible to reduce the possibility of missing a photo opportunity by shortening the shooting time.

  Further, according to the imaging apparatus 100, it is possible to perform focus adjustment by switching between the contrast detection method and the phase difference detection method in accordance with the exposure value determined before the main photographing. When the exposure value is small, the focus detection accuracy is higher in the contrast detection method than in the phase difference detection method. Therefore, the focus adjustment is performed according to the flow shown in FIG. It can be performed. The threshold value th may be an exposure value when the focus adjustment accuracy of the contrast detection method is higher than the focus adjustment accuracy of the phase difference detection method when the exposure value is lower than this.

  In the flowchart of FIG. 8, the contrast detection method and the phase difference detection method are switched according to the exposure value. However, the phase difference detection method may always be performed regardless of the exposure value. That is, in FIG. 8, steps S3 and S4 may be deleted, and the flow may proceed to step S5 after step S2.

  Further, when the pixel unit 10 and the pixel unit 11 function as the pixel unit for pupil division, the captured image signal obtained from all the pixel units 10 and the captured image signal obtained from all the pixel units 11 are between In the pupil division direction (row direction X) of the pixel unit 10 and the pixel unit 11, parallax occurs. For this reason, the two captured image signals are independently processed to generate two captured image data with parallax, and these are recorded in a format that can be stereoscopically displayed, whereby the imaging apparatus 100 has a 3D shooting function. It can also be made.

  FIG. 10 is a flowchart for explaining a shooting operation when the imaging apparatus 100 shown in FIG. 1 is equipped with a 3D shooting mode (a mode for shooting and recording a plurality of captured image data having parallax).

  First, the CPU 46 determines the shooting mode, and when the shooting mode is the 3D shooting mode (step S21: YES), the CPU 46 performs the processing after step S22. When the shooting mode is a shooting mode other than the 3D shooting mode, for example, a 2D shooting mode (a mode for recording captured image data without parallax) (step S21: NO), the processing after step S1 in FIG. 8 is performed. Do.

  In step S22, the CPU 46 changes the voltage applied to the charge discharge region 15 from the low level to the high level via the device control unit 47.

  Next, when the shutter button included in the operation unit 48 is half-pressed (step S23: YES), the CPU 46 performs provisional photographing for focus adjustment with the image pickup device 44, and a captured image signal obtained by the provisional photographing. Based on (the two imaged image signals from all the pixel units 10 and the imaged image signals from all the pixel units 11), focus adjustment processing by the phase difference detection method is performed (step S24).

  When the process of step S24 is completed and the shutter button has not been fully pressed during a certain period (step S25: NO), the CPU 46 returns the process to step S24.

  When the processing in step S24 is completed and the shutter button is fully pressed during a certain period (step S25: YES), the CPU 46 uses the image sensor 44 to perform the main operation according to the imaging conditions such as the in-focus position determined in step S24. Take a picture. The captured image signal output from the imaging element 44 by the actual photographing (two captured image signals from all the pixel units 10 and two captured image signals from all the pixel units 11) is processed by the image processing unit 49. Then, left-eye captured image data and right-eye captured image data are generated. Then, these two captured image data are recorded on the memory card 55 in a format capable of stereoscopic display (step S26).

  The CPU 46 determines whether or not to end the 3D shooting mode after executing the main shooting. When the 3D shooting mode is ended (step S27: YES), the voltage applied to the charge discharge region 15 is changed from a high level to a low level. The level is changed to end the 3D shooting mode. If the 3D shooting mode is not terminated (step S27: NO), the process returns to step S23.

  As described above, according to the imaging apparatus 100 illustrated in FIG. 1, the 2D shooting mode and the 3D shooting mode can be easily switched only by electrical control. In addition, such a function can be realized by a single photographing optical system and a single image sensor 44. For this reason, the imaging device which can use 2D imaging | photography and 3D imaging | photography simultaneously can be implement | achieved compactly and at low cost.

  Further, according to the imaging apparatus 100, in the 2D shooting mode, since the main shooting is performed in the low level state, it is possible to sufficiently secure the sensitivity of all the pixel units and correspond to the number of all the pixel units. Captured image data of the number of pixels can be created. Therefore, high-sensitivity and high-resolution captured image data can be obtained without performing complicated image processing.

  In the description so far, all the pixel parts included in the image sensor 44 are pixel parts for pupil division / photographing. However, as described in Patent Documents 1 and 2, they are included in the image sensor 44. A part of all the pixel parts may be pixel parts for pupil division and photographing, and the remaining pixel parts may be pixel parts dedicated to photographing.

  In this case, the pixel unit dedicated to photographing is the same as the configuration of either the pixel unit 10 or the pixel unit 11, or a configuration different from the pixel units 10 and 11 (for example, the element isolation region 14, the pixel unit 10, The charge discharge region 15 and the barrier region 16 may be deleted, and the surface P region 12 and the charge storage region 13 may be expanded in the region where these existed. In the case where the pixel unit dedicated to shooting is configured differently from the pixel units 10 and 11, there is a slight sensitivity difference between the pixel unit dedicated to shooting and the pixel units 10 and 11 during main shooting performed in a low level state. However, this difference in sensitivity is not so high that a defect correction process by signal interpolation from the surroundings is necessary. For this reason, it is possible to easily align them by adjusting the gains of signals obtained from the pixel portions 10 and 11. Therefore, even in a configuration in which a pixel unit dedicated to photographing is provided, the photographing time can be shortened. However, in such a configuration, a 3D shooting function cannot be provided.

  Next, a modified example of the image pickup device 44 mounted on the image pickup apparatus 100 shown in FIG. 1 will be described.

(First modification)
FIG. 11 is a diagram illustrating a first modification of the image sensor 44 mounted on the image capturing apparatus 100 illustrated in FIG. 1, and corresponds to FIG. 3.

  The cross-sectional configuration shown in FIG. 11 is the same as the cross-sectional configuration shown in FIG. 3 except that the charge discharge region 15 and the barrier region 16 are shared by the pixel unit 10 and the pixel unit 11.

  As illustrated in FIG. 2, when the pixel units 10 and 11 constituting the pair are arranged adjacent to each other, the charge discharging region 15 is shared by the pixel unit 10 and the pixel unit 11 as illustrated in FIG. 11. Can be combined into one. By doing so, the number of wirings connected to the charge discharging region 15 can be reduced as compared with the case of FIG. 3, and the degree of freedom of wiring layout can be improved. Further, by making the charge discharge region 15 and the barrier region 16 into one in the pixel unit 10 and the pixel unit 11 constituting the pair, manufacturing variations of the charge discharge region 15 and the barrier region 16 for each pixel unit are absorbed. Image quality can be improved. Note that the barrier region 16 may be separately provided in the pixel portion 10 and the pixel portion 11 without being shared.

(Second modification)
FIG. 12 is a diagram illustrating a second modification of the image sensor 44 mounted on the image capturing apparatus 100 illustrated in FIG. 1, and corresponds to FIG. 3.

  In the example shown in FIGS. 3 and 11, the barrier region 16 is formed on the surface side of the silicon substrate with respect to the charge generation region 17, and the charge discharging region 15 is formed on the surface side of the silicon substrate with respect to the barrier region 16. . On the other hand, in the configuration shown in FIG. 12, a barrier region 16 is formed in the same layer as the charge generation region 17, and next to the barrier region 16, charge discharge regions (15a, 15b) extending to the surface side of the silicon substrate. 3 is different from FIG.

  As shown in FIG. 12, a barrier region 16 is formed on the right side in the row direction X of the charge generation region 17 in the silicon substrate of the pixel portion 10. Also in the configuration shown in FIG. 12, the portion where the charge generation region 17 and the barrier region 16 are in contact exists on the right side of the center of the charge generation region 17 in the row direction X.

  A charge discharge region 15 b made of an impurity layer having the same conductivity type as that of the charge generation region 17 is formed on the right side of the barrier region 16.

  Between the charge discharge region 15b and the silicon substrate surface, a charge discharge region 15a made of an impurity layer having the same conductivity type as the charge discharge region 15b and having an impurity concentration higher than that of the charge discharge region 15b is formed. In the example of FIG. 12, the charge discharge region 15b and the charge discharge region 15a are shared by the pixel units 10 and 11 constituting the pair, but may be formed separately by the pixel unit 10 and the pixel unit 11. . The charge discharge region 15a and the charge discharge region 15b have the same function as the charge discharge region 15 described with reference to FIG. 3, and the potential of the barrier region 16 in contact therewith is controlled by controlling the voltage applied thereto. Can be controlled.

  The width of the charge storage region 13 and the surface P region 12 in the row direction X is the same as that of the charge generation region 17, and there is an element isolation region between the charge storage region 13 and the surface P region 12 and the charge discharge region 15a. 14 is formed. The element isolation region 14 separates the charge accumulation region 13 and the surface P region 12 from the charge discharge region 15b, the charge discharge region 15a, and the barrier region 16.

  A wiring 30 is connected to the charge discharge region 15 a, and the wiring 30 is connected to the device control unit 47.

  The configuration of the pixel unit 11 is obtained by inverting the pixel unit 10 in the row direction X.

  FIG. 13 is a diagram for explaining the principle of pupil division of the pixel portions 10 and 11 shown in FIG. 12, and a high level voltage that causes the potential barrier formed by the barrier region 16 to disappear is applied to the charge discharging region 15a. It is the figure which showed the state when it applied.

  When a high-level voltage is applied to the charge discharge region 15a, the potentials of the charge discharge region 15b and the charge discharge region 15a become deeper, and the potential of the barrier region 16 moves in a deeper direction due to this, thereby moving the barrier region. The potential barrier formed by 16 disappears. That is, a depletion layer spreads from the charge discharge region 15b as shown by the hatched line in FIG. 13, and the charges generated in the region shown by the hatched line do not move to the charge accumulation region 13 but pass through the charge discharge region 15b. Then, it moves to the charge discharge region 15a and is discharged out of the substrate from here.

  Thus, even with the configuration as shown in FIG. 12, pupil division can be performed based on the same principle as described above.

  According to the configuration shown in FIG. 12, the charge generation region 17, the charge storage region 13, and the surface P region 12 can have the same area in plan view, and these shapes are simplified. For this reason, even when a microlens is formed on the back surface of the silicon substrate corresponding to the pixel portion, the design is facilitated.

  In addition, according to the configuration shown in FIG. 12, since the charge discharge region 15b can be formed at a position close to the back surface of the silicon substrate, the wiring 30 is formed above the back surface of the silicon substrate, and from the back surface side of the silicon substrate. The wiring 30 and the charge discharge region 15b can be connected. As a result, the degree of freedom of design on the surface side of the silicon substrate can be improved. In addition, it is conceivable to provide a light shielding film on the boundary between the pixel portions above the back surface of the silicon substrate for the purpose of preventing color mixing. When this light shielding film is provided, this light shielding film is connected to the wiring 30. It is also possible to use both, and the manufacturing process can be simplified.

  In addition, the configuration illustrated in FIG. 12 is not limited to the backside illumination type but can be applied to a front side illumination type imaging device. When the structure shown in FIG. 12 is applied to the surface irradiation type, a color filter, a microlens, or the like may be disposed on the surface side of the silicon substrate, and light may be incident from the surface side. In this case, the long wavelength light (red light) of the incident light reaches the charge generation region 17 in the deep part of the silicon substrate. Therefore, the charge corresponding to the long wavelength light generated in the charge generation region 17 in the vicinity of the barrier region 16 can be discharged from the charge discharge region 15a in the high level state. On the other hand, short-wavelength light (blue and green light) of incident light hardly reaches the charge generation region 17 and is converted into charges in the charge accumulation region 13, so that even in a high level state, This can hardly be discharged from the charge discharge region 15a. Therefore, even in the surface irradiation type, pupil division can be performed in principle for light having a long wavelength among incident light.

(Third modification)
FIG. 14 is a diagram showing a third modification of the image sensor 44 mounted on the imaging device 100 shown in FIG. 1, and the configuration inside the silicon substrate when the pixel unit 10 of FIG. 2 is viewed from the silicon substrate surface side. It is the figure which showed arrangement | positioning of an element. 15 is a schematic cross-sectional view taken along line BB in FIG. 14, FIG. 16 is a schematic cross-sectional view taken along line CC in FIG. 14, and FIG. 17 is a schematic cross-sectional view taken along line DD in FIG. .

  In the example shown in FIGS. 3, 11, and 12, the charge accumulation region 13 is formed on the surface side of the silicon substrate from the charge generation region 17. On the other hand, in the third modified example, the point that the charge accumulation region 13 is formed in the same layer as the charge generation region 17 is significantly different from those in FIGS.

  As shown in FIGS. 14 and 15, the charge generation region 17 and the charge storage region 13 are formed side by side in the column direction Y and in contact with each other in a P-type silicon substrate. Since the impurity concentration of the charge storage region 13 is higher than that of the charge generation region 17, a potential slope is formed from the charge generation region 17 toward the charge storage region 13, and the charge generated in the charge generation region 17 Move to area 13 and accumulate. A surface P layer 12 is formed between the charge generation region 17 and the charge storage region 13 and the silicon substrate surface.

  As shown in FIGS. 14 and 16, a barrier region 16 is formed on the left side of the charge generation region 17 in contact therewith. A control electrode 72 is formed on the barrier region 16 via an insulating film 71. The control electrode 72 is connected to the wiring 30 described in FIG. 3. By controlling the voltage supplied to the control electrode 72, a state in which a potential barrier for the charge generation region 17 is formed in the barrier region 16, and It is possible to switch the state where the potential barrier disappears.

A charge discharging region 15 is formed on the left side of the barrier region 16 in contact therewith. The charge discharge region 15 is connected to a fixed power source. As shown in FIG. 14, the charge storage region 13, the barrier region 16, and the charge discharge region 15 are separated by a P-type silicon substrate.
In the image sensor of the third modification, the charge generation region 17, the barrier region 16, and the charge discharge region 15 are all formed in the same layer. For this reason, instead of controlling the potential of the charge discharging region 15, the high level state and the low level state can be switched by controlling the voltage of the control electrode 72. Of course, the wiring 30 may be connected to the charge discharging region 15 to switch between the low level state and the high level state. In this case, the control electrode 72 is not necessary.

  As shown in FIG. 17, a semiconductor region of the MOS circuit 70 illustrated in FIG. 4 is formed on the left side of the charge storage region 13 with a slight gap. A transfer gate electrode 73 is formed above the silicon substrate between the floating diffusion and the charge storage region 13 in the semiconductor region. A charge readout region 40 is formed in a region of the silicon substrate that overlaps the transfer gate electrode 73 in plan view. It is preferable to provide a light-shielding film that shields light other than the charge generation region 17 and the charge storage region 13 above the back surface of the silicon substrate.

  The pixel unit 10 illustrated in FIG. 2 has been described so far, but the pixel unit 11 is obtained by inverting the plan view illustrated in FIG. Since the pupil division pixel unit is also used for photographing, it is preferable to arrange the photoelectric conversion regions of all the pixel units 10 and 11 in two dimensions at equal intervals.

  As shown in FIG. 16, since the barrier region 16 is in contact with the left end of the charge generation region 17 in the pixel unit 10, the barrier region 16 is in contact with the right end of the charge generation region 17 in the pixel unit 11. For this reason, it is possible to perform pupil division based on the same principle as described above by driving the image sensor in a high level state.

  According to the configuration shown in FIG. 14, since the potential of the barrier region 16 can be directly controlled by the control electrode 72, element design is facilitated. As shown in FIGS. 3, 11, and 12, according to the configuration in which the charge generation region 17 and the charge storage region 13 are stacked in the silicon substrate, the ratio of the charge generation region in the pixel portion is shown in FIG. There is an advantage that it can be increased more than the configuration shown, and high sensitivity can be achieved.

  In the configuration of the pixel unit illustrated in FIG. 14, for example, the configuration illustrated in FIG. 14 is the configuration of the pixel unit 11, and the pixel unit 10 is obtained by inverting the configuration of FIG. 14 in the row direction X. The charge discharge region 15 and the readout circuit 70 can be shared by the pixel portion 10 and the pixel portion 11. If these can be shared, the areas of the charge generation region 17 and the charge storage region 13 of each pixel portion can be increased, and high sensitivity can be achieved.

  In addition, the configuration illustrated in FIG. 14 is not limited to the backside illumination type but can be applied to a front side illumination type imaging device. When the structure shown in FIG. 14 is applied to the surface irradiation type, a color filter, a microlens, or the like may be disposed on the surface side of the silicon substrate, and light may be incident from the surface side. In this case, as indicated by broken lines in FIGS. 15 to 17, a light shielding film W that shields light other than the charge generation region 17 and the charge accumulation region 13 is provided above the silicon substrate surface. Even when the configuration of FIG. 14 is a surface irradiation type, the charge generation region 17 and the charge accumulation region 13 become the photoelectric conversion region of the pixel portion. According to the configuration shown in FIG. 14, pupil division can be performed regardless of the wavelength of incident light even in the case of the surface irradiation type.

(Fourth modification)
FIG. 18 is a diagram illustrating a fourth modification of the imaging element 44 mounted on the imaging device 100 illustrated in FIG. 1, and corresponds to FIG. 2. The image pickup device 44a shown in FIG. 18 has the same configuration as the image pickup device 44 shown in FIG. 2 except that a color filter is provided above the back surface of the silicon substrate (surface on the light incident side of the silicon substrate) of each pixel unit. It is.

  In FIG. 18, for pixel units 10 and 11 having an R color filter that transmits red light, a letter “R” is entered in the block, and pixel units 10 and 11 having a G color filter that transmits green light. For 11, the letter “G” is entered in the block, and for the pixel portions 10 and 11 having the B color filter that transmits blue light, the letter “B” is entered in the block.

  In the image sensor 44a shown in FIG. 18, the arrangement of the color filters included in all the pixel units 10 is a Bayer arrangement as a whole, and the arrangement of the color filters included in all the pixel units 11 is also a Bayer arrangement as a whole. ing. The color filters included in the two pixel portions 10 and 11 constituting the pair are of the same color.

  With such a configuration, color imaging can also be handled.

  The imaging device 100 equipped with the imaging element 44a obtains from the pixel units 10 and 11 of the pair for each pair when the imaging element 44a performs main photographing in a low level state to obtain one captured image data. The two obtained image signals are added to generate one image signal, and image processing is performed on the image signal including the same number of image signals as the number of all pairs, and one image data is generated and recorded. That's fine. By doing in this way, the picked-up image data of the color which further improved the sensitivity by signal addition can be obtained.

  Note that the configuration of the two pixel units that constitute the pair of the image sensor 44a may be the configuration described in FIGS.

(Fifth modification)
FIG. 19 is a diagram illustrating a fifth modification of the image sensor 44 mounted on the image capturing apparatus 100 illustrated in FIG. 1, and corresponds to FIG. The image pickup device 44b shown in FIG. 19 is the same as that shown in FIG. 19 except that a color filter is provided above the back surface of the silicon substrate of each pixel portion (the surface on the light incident side of the silicon substrate) and the arrangement of each pixel portion is changed. This is the same configuration as the image sensor 44 shown in FIG.

  In FIG. 19, for the pixel units 10 and 11 having the R color filter that transmits red light, the letter “R” is written in the block, and the pixel units 10 and G that have the G color filter that transmits green light. For 11, the letter “G” is entered in the block, and for the pixel portions 10 and 11 having the B color filter that transmits blue light, the letter “B” is entered in the block.

  19 are arranged in a square lattice pattern in the row direction X and the column direction Y, and the pixel section 11 is arranged in a square lattice pattern in the row direction X and the column direction Y. The pixel portion 10 and the pixel portion 11 have the same arrangement pitch and total number. The array of color filters included in all the pixel units 10 is a Bayer array as a whole, and the array of color filters included in all the pixel units 11 is also a Bayer array as a whole.

  The pixel unit 11 is arranged at a position where all the pixel units 10 are shifted diagonally by 45 ° in the lower right direction. Further, the pixel unit 11 adjacent to each pixel unit 10 in the same direction (in the diagonally lower right direction in the example of FIG. 19) includes a color filter having the same color as the color filter included in each pixel unit 10. As described above, the pixel unit 10 and the pixel unit 11 are arranged. Each pixel unit 10 and a pixel unit 11 adjacent to each pixel unit 10 in the diagonally lower right direction form a pair of pixel units for pupil division.

  A cross-section A′-A ′ in FIG. 19 is as shown in FIG. 3. The configuration of the two pixel units constituting the pair in FIG. 19 may be the configuration described with reference to FIGS.

  With such a configuration, color imaging can also be handled. In addition, compared with the configuration shown in FIG. 18, the area per pixel portion can be increased, and further higher sensitivity can be achieved.

(Sixth modification)
FIG. 20 is a diagram illustrating a sixth modification of the image sensor 44 mounted on the image capturing apparatus 100 illustrated in FIG. 1, and corresponds to FIG. 2. The imaging device 44c shown in FIG. 20 is the same as that shown in FIG. 20 except that a color filter is provided above the back surface of the silicon substrate of each pixel portion (the surface on the light incident side of the silicon substrate) and the arrangement of each pixel portion is changed. This is the same configuration as the image sensor 44 shown in FIG.

  In FIG. 20, for the pixel units 10 and 11 having the R color filter that transmits red light, the letter “R” is entered in the block, and the pixel units 10 and 11 having the G color filter that transmits green light. For 11, the letter “G” is entered in the block, and for the pixel portions 10 and 11 having the B color filter that transmits blue light, the letter “B” is entered in the block.

  In FIG. 2, the odd-numbered pixel portions are the pixel portions 10 and the even-numbered pixel portions are the pixel portions 11. However, in the imaging device 44 c, the pixel portions 10 and the pixel portions 11 are alternately arranged every two columns. Yes. The arrangement of the color filters included in all the pixel portions is a Bayer arrangement as a whole. In the imaging device 44c, as shown by a solid line or a broken line in the figure, the pixel unit 10 and a pixel unit 11 including a color filter of the same color as the pixel unit 10 closest to the pixel unit 10 in the row direction X A pair of pixel portions for division is configured.

  With such a configuration, color imaging can also be handled. According to the imaging device 44c, since the color filter array is a Bayer array as a whole, the imaging of the pixel unit 10 and the pixel unit 11 is performed when one imaging image data is obtained by performing actual imaging in a low level state. Without adding signals, a Bayer array captured image signal can be obtained, image processing is facilitated, and high-resolution captured image data can be generated.

  2, 18, and 20 exemplify a case where pupil division is performed in the row direction X, the direction in which pupil division is performed is arbitrary, and may be, for example, the column direction Y. In this case, in the imaging device shown in FIGS. 2, 18, and 20, if all the pixel units are arranged 90 ° rotated to the right or left, imaging having a pupil division function in the column direction Y is possible. An element can be realized.

  In the case of the configuration shown in FIG. 19, pupil division can be performed in a direction of 45 ° with respect to each of the row direction X and the column direction Y. By providing the barrier region 16 at the right corner) and the barrier region 16 at the left end of the pixel unit 11 (left corner of the quadrangular block), pupil division is performed in the row direction X, The barrier region 16 is provided at the lower end (the lower corner of the quadrangular block), and the barrier region 16 is provided at the upper end of the pixel unit 11 (the upper corner of the quadrangular block), thereby performing pupil division in the column direction Y. It is also possible to do.

  In the configurations shown in FIGS. 2, 18, 19, and 20, the center in plan view of the barrier region 16 of each of the pixel portions 10 and 11 constituting the pair is the center in plan view of the charge generation region 13. On the other hand, although it decenters in the direction which approaches each other in the direction which performs pupil division, you may decenter the center of this each barrier area | region 16 in the direction away from each other in the direction which performs pupil division. For example, in the cross-sectional view of FIG. 3, the structure in the silicon substrate of the pixel unit 10 is horizontally reversed, and the structure in the silicon substrate of the pixel unit 11 is horizontally reversed. It can be performed. The structure shown in FIG. 3 is preferable because the charge discharge region 15 can be shared by a pair of pixel portions as illustrated in FIG.

  Further, the direction in which pupil division is performed is not limited to one direction, and may be a plurality of directions. Hereinafter, an image sensor capable of performing pupil division in a plurality of directions will be described.

(Seventh modification)
FIG. 21 is a diagram illustrating a seventh modification of the image sensor 44 mounted on the image capturing apparatus 100 illustrated in FIG. 1, and corresponds to FIG. 2.

  The imaging element 44e shown in FIG. 21 has a configuration in which a plurality of pixel portions are arranged in the same arrangement as in FIG. A significant difference from FIG. 19 is that the four pixel portions 60a, 60b, 60c, and 60d adjacent to each other are made into one group, and the color filters of each of the four pixel portions in the group have the same color. The charge drain region 15 is shared by the four pixel portions. In FIG. 21, for a pixel portion having an R color filter that transmits red light, a letter “R” is written in the block, and for a pixel portion having a G color filter that transmits green light, For the pixel portion having a B color filter that transmits blue light, the letter “B” is entered in the block.

  Of the four pixel units 60a, 60b, 60c, and 60d included in each group, the pixel unit 60b and the pixel unit 60d constitute a pupil division pair that performs pupil division in the row direction X, and the pixel unit 60a and the pixel unit The unit 60c forms a pair for pupil division that performs pupil division in the column direction Y. The configurations described in FIGS. 3, 11, 12, and 14 can be applied to the configuration of the pixel portions of all pupil division pairs. For example, the cross section taken along the line aa and the line bb shown in FIG. 21 is the same as the cross section shown in FIG. 11 or FIG. However, the charge discharge region 15 (15a, 15b) included in each pixel unit 60a, 60b, 60c, 60d is only one in the group, and is shared by the four pixel units 60a, 60b, 60c, 60d. Has been.

  With such a configuration, it is possible to perform pupil division in two directions. In addition, according to this configuration, the charge discharge region 15 can be shared by the four pixel portions, so that the wiring 30 can be easily routed.

  In addition, when the main photographing is performed with the image pickup element 44e in the low level state, four image pickup signals obtained from each group are added to generate a picked-up image signal composed of image pickup signals for the total number of groups. One picked-up image data may be generated and recorded by image processing. In addition, when actual imaging is performed with the imaging element 44e in a high level state, captured image data (upper) is generated by performing image processing on captured image signals obtained from all the pixel units 60a, and all pixel units 60b. The captured image signal obtained from the image is processed to generate captured image data (left), the captured image signal obtained from all the pixel units 60c is processed to generate captured image data (lower), and all pixels The captured image signal obtained from the unit 60d is subjected to image processing to generate captured image data (right), which are recorded in association with each other.

  For example, since the captured image data (right) and the captured image data (left) are data having parallax in the row direction X, they can be displayed in a stereoscopic manner. Moreover, since the captured image data (upper) and the captured image data (lower) are data having parallax in the column direction Y, they can be displayed in a stereoscopic manner. As described above, according to the imaging element 44e, a set of captured image data having parallax in different directions can be obtained by one shooting, and stereoscopic images when the same subject is viewed from various viewpoints can be obtained. It becomes possible to reproduce.

  In addition, each pixel portion of the image sensor 44e may not be equipped with a color filter. Even in this case, it is possible to obtain monochrome captured image data having parallax in different directions by one shooting.

  Moreover, although the example which reads an electron as a signal was shown in the above description, the structure which reads a hole as a signal may be sufficient. In this case, the P type and the N type described so far may be reversed.

  As described above, the following items are disclosed in this specification.

  The disclosed image sensor is an image sensor having a plurality of pairs of pixel parts for pupil division, and each of the two pixel parts constituting the pair is formed in a semiconductor substrate and generates a charge. Type charge generation region and charge accumulation of the first conductivity type that is formed in contact with the charge generation region in the semiconductor substrate and has a higher impurity concentration than the charge generation region that accumulates the charge generated in the charge generation region A barrier region of the opposite conductivity type to the first conductivity type formed in contact with only the charge generation region among the charge storage region and the charge generation region, and the barrier region adjacent to the barrier region. A portion where the charge generation region of one of the two pixel portions constituting the pair is in contact with the barrier region is divided into pupils rather than the center of the charge generation region. One direction The portion where the charge generation region of the other pixel portion of the two pixel portions constituting the pair is in contact with the barrier region is located on the other side in the pupil division direction from the center of the charge generation region. .

  In the disclosed imaging device, the imaging device reads a signal corresponding to the charge accumulated in the charge accumulation region by a readout circuit formed on a surface side opposite to the light incident side surface of the semiconductor substrate. Includes those that are back-illuminated.

  In the disclosed imaging device, the cross-sectional shape in the pupil division direction of the charge generation region, the charge accumulation region, the barrier region, and the charge discharge region of one pixel portion of the two pixel portions constituting the pair is: The cross-sectional shape in the pupil division direction of the charge generation region, the charge accumulation region, the barrier region, and the charge discharge region of the other pixel portion of the two pixel portions constituting the pair is inverted in the pupil division direction. It is what has become.

  With this configuration, pupil division can be performed with high accuracy.

  In the disclosed imaging device, the charge generation region included in each of the two pixel portions constituting the pair is formed on a light incident side surface of the semiconductor substrate, and the two pixel portions constituting the pair The charge storage region included in each of the semiconductor substrate is formed on the surface of the semiconductor substrate opposite to the light incident side.

  In the disclosed imaging device, the barrier region is formed on the opposite surface side of the semiconductor substrate with respect to the charge generation region, and the charge discharge region is disposed on the opposite surface of the semiconductor substrate with respect to the barrier region. It is formed on the side.

  In the disclosed imaging device, the barrier region is formed in the same layer as the charge generation region, and the charge discharge region is formed to extend from the adjacent side of the barrier region to the opposite surface side of the semiconductor substrate. It is what.

  The disclosed imaging device includes a voltage application wiring connected to the charge discharge region, and the wiring is provided above the light incident side surface of the semiconductor substrate.

  In the disclosed imaging device, the charge generation region, the charge storage region, the barrier region, and the charge discharge region included in each of the two pixel portions constituting the pair are formed in the same layer. is there.

  In the disclosed imaging device, all pixel units included in the imaging device are pixel units for pupil division, and all the pixel units are a plurality of first pixel units arranged two-dimensionally. And a plurality of second pixel portions arranged two-dimensionally, each of the first pixel portion and the second pixel portion being colored above the light incident side surface of the semiconductor substrate. A color filter included in the plurality of first pixel portions as a whole in a Bayer array, and a color filter included in the plurality of second pixel portions as a whole in a Bayer array. One pixel portion and the plurality of second pixel portions include a color filter of the same color as the color filter included in each first pixel portion at a position adjacent to each first pixel portion in the same direction. Arranged so that the second pixel part is arranged And which, with the first pixel unit, those constituting the pair and said second pixel portion in which the to the first pixel unit adjacent in the same direction.

  In the disclosed imaging device, all the pixel portions included in the imaging device are pixel portions for pupil division, and each of the pixel portions is colored above the surface on the light incident side of the semiconductor substrate. The color filters included in all the pixel portions are configured as a Bayer array as a whole, and the color filters of the same color as the color filters included in the pixel portions located closest to the pixel portions are provided. The pixel portion has the pair.

  In the disclosed imaging device, two pixel portions constituting the pair are arranged adjacent to each other, and the charge discharge region is shared by the two pixel portions.

  In the disclosed imaging device, the pair includes two types of pairs having different pupil division directions, the four pixel portions constituting the two types of pairs are arranged adjacent to each other, and the charge discharge region is This is shared by the four pixel portions.

  In the disclosed imaging device, all the pixel portions included in the imaging device are pixel portions for pupil division, and each of the pixel portions is colored above the surface on the light incident side of the semiconductor substrate. The color filters included in the four pixel portions that include the filter and constitute the two types of pairs have the same color.

  The disclosed imaging device includes: a first imaging process that performs imaging in a state where a potential barrier with respect to the charge generation region is formed by the barrier region, the focus lens disposed in front of the imaging device; A drive unit that switches between a second imaging process that performs imaging in a state where the potential barrier is eliminated, and a position of the focus lens based on a captured image signal obtained by provisional imaging with the imaging element A focus adjustment unit that performs a focus adjustment process, and the focus adjustment process performs phase adjustment by a phase difference detection method based on a captured image signal obtained from the image sensor in the second imaging process. Including the AF process, the driving unit performs the first imaging process at the time of the main photographing performed after the focus adjustment process.

  In the disclosed imaging apparatus, the focus adjustment process includes a contrast AF process for performing focus adjustment by a contrast detection method based on a captured image signal obtained from the image sensor in the first imaging process, and the focus adjustment unit The phase difference AF process is executed when the exposure value calculated at the time of shooting before the main shooting is equal to or greater than the threshold value, and the contrast AF process is executed when the exposure value is less than the threshold value.

  The disclosed imaging apparatus includes a 3D shooting mode for shooting and recording a plurality of captured image data with parallax, and in the 3D shooting mode, the driving unit performs the provisional shooting and the book in the second imaging process. The photographing is performed, and the focus adjustment unit performs the phase difference AF process.

  The disclosed imaging method is an imaging method using the imaging element, wherein a first imaging process that performs imaging in a state where a potential barrier with respect to the charge generation region is formed by the barrier region, and the potential barrier disappears. A driving step for switching between the second photographing process for photographing in a state of being performed and a position of a focus lens disposed in front of the image sensor based on a captured image signal obtained by provisional photographing with the image sensor A focus adjustment step of performing a focus adjustment process for adjusting the focus, and the focus adjustment process performs focus adjustment by a phase difference detection method based on a captured image signal obtained from the image sensor in the second imaging process. Including the phase difference AF process, the driving step performs the first imaging process during the main imaging performed after the focus adjustment process.

  In the disclosed imaging method, the focus adjustment process includes a contrast AF process in which focus adjustment is performed by a contrast detection method based on a captured image signal obtained from the image sensor in the first imaging process, and the focus adjustment step Then, the phase difference AF process is executed when the exposure value calculated at the time of shooting before the main shooting is equal to or greater than the threshold value, and the contrast AF process is executed when the exposure value is less than the threshold value.

  In the disclosed imaging method, in the 3D imaging mode in which a plurality of captured image data with parallax is captured and recorded, the provisional imaging and the main imaging are performed in the second imaging process, and the focus is performed in the phase difference AF process. To make adjustments.

10, 11 Pupil division pixel portion 13 Charge accumulation region 15 Charge discharge region 16 Barrier region 17 Charge generation region 30 Wiring

Claims (19)

An imaging device having a plurality of pairs of pixel parts for pupil division,
The two pixel portions constituting the pair are each formed in a semiconductor substrate to generate a charge, a first conductivity type charge generation region, and formed in contact with the charge generation region in the semiconductor substrate. A charge accumulation region of the first conductivity type having a higher impurity concentration than the charge generation region for accumulating the charge generated in the region, and the charge accumulation region and the charge generation region only in contact with the charge generation region. A barrier region of a conductivity type opposite to the first conductivity type, and a charge discharging region of the first conductivity type formed adjacent to the barrier region,
The portion where the charge generation region of one of the two pixel portions constituting the pair is in contact with the barrier region is on one side in the pupil division direction from the center of the charge generation region,
The part where the charge generation region of the other pixel portion of the two pixel portions constituting the pair is in contact with the barrier region is on the other side in the pupil division direction from the center of the charge generation region. The imaging device according to claim 1,
The imaging device is a back-illuminated imaging device in which a signal corresponding to the charge accumulated in the charge accumulation region is read out by a readout circuit formed on a surface opposite to the light incident surface of the semiconductor substrate. . The image sensor according to claim 1 or 2,
The cross-sectional shape in the pupil division direction of the charge generation region, the charge storage region, the barrier region, and the charge discharge region of one pixel portion of the two pixel portions constituting the pair is the two of the two pixel portions constituting the pair. An imaging device in which the cross-sectional shape in the pupil division direction of the charge generation region, the charge accumulation region, the barrier region, and the charge discharge region of the other pixel portion of the pixel portion is inverted in the pupil division direction . The imaging device according to any one of claims 1 to 3,
The charge generation region included in each of the two pixel portions constituting the pair is formed on a light incident side surface side of the semiconductor substrate,
An image pickup device in which the charge accumulation region included in each of two pixel portions constituting the pair is formed on a surface of the semiconductor substrate opposite to the light incident side. The imaging device according to claim 4,
The barrier region is formed on the opposite surface side of the semiconductor substrate from the charge generation region;
An image sensor in which the charge discharge region is formed on the opposite surface side of the semiconductor substrate with respect to the barrier region. The imaging device according to claim 4,
The barrier region is formed in the same layer as the charge generation region;
An image sensor in which the charge discharge region is formed to extend from the side of the semiconductor substrate to the opposite surface side from the barrier region. The imaging device according to claim 6,
A voltage application wiring connected to the charge discharge region;
An imaging device in which the wiring is provided above a surface on the light incident side of the semiconductor substrate. The imaging device according to any one of claims 1 to 3,
An imaging device in which the charge generation region, the charge storage region, the barrier region, and the charge discharge region included in each of the two pixel portions constituting the pair are formed in the same layer. The imaging device according to any one of claims 1 to 8,
All the pixel portions included in the image sensor are the pupil division pixel portions,
All the pixel parts are composed of a plurality of first pixel parts arranged two-dimensionally and a plurality of second pixel parts arranged two-dimensionally,
Each of the first pixel portion and the second pixel portion includes a color filter above a light incident side surface of the semiconductor substrate,
The color filters included in the plurality of first pixel portions as a whole are Bayer arrays,
The color filters included in the plurality of second pixel portions as a whole are Bayer arrays,
The plurality of first pixel portions and the plurality of second pixel portions have the same color as the color filters included in the first pixel portions at positions adjacent to the first pixel portions in the same direction. The second pixel portion including a color filter is arranged to be disposed,
An imaging device in which the first pixel portion and the second pixel portion adjacent to the first pixel portion in the same direction constitute the pair. The imaging device according to any one of claims 1 to 8,
All the pixel portions included in the image sensor are the pupil division pixel portions,
Each of the pixel portions includes a color filter above the light incident side surface of the semiconductor substrate,
The color filters included in all the pixel portions are in a Bayer array as a whole,
The image sensor which comprises the said pixel part and the pixel part which has a color filter of the same color as the color filter contained in the said pixel part in the position nearest to the said pixel part as said pair. The image sensor according to any one of claims 1 to 9,
Two pixel parts constituting the pair are arranged adjacent to each other,
An image sensor in which the charge discharge region is shared by the two pixel portions. The imaging device according to any one of claims 1 to 8,
The pair includes two types of pairs with different pupil division directions,
The four pixel parts constituting the two types of pairs are arranged adjacent to each other,
An image sensor in which the charge discharge region is shared by the four pixel portions. The imaging device according to claim 12, wherein
All the pixel portions included in the image sensor are the pupil division pixel portions,
Each of the pixel portions includes a color filter above the light incident side surface of the semiconductor substrate,
An image sensor in which the color filters included in the four pixel portions constituting the two types of pairs have the same color. The image sensor according to any one of claims 1 to 13,
A focus lens disposed in front of the image sensor;
A drive unit that switches between a first imaging process that performs imaging in a state where a potential barrier for the charge generation region is formed by the barrier region and a second imaging process that performs imaging in a state where the potential barrier is extinguished. When,
A focus adjustment unit that performs a focus adjustment process for adjusting the position of the focus lens based on a captured image signal obtained by provisional imaging with the image sensor;
The focus adjustment process includes a phase difference AF process for performing focus adjustment by a phase difference detection method based on a captured image signal obtained from the image sensor in the second imaging process,
The drive unit is an image pickup apparatus that performs the first image pickup process during main photographing performed after the focus adjustment process. The imaging device according to claim 14,
The focus adjustment process includes a contrast AF process for performing focus adjustment by a contrast detection method based on a captured image signal obtained from the image sensor in the first imaging process,
The focus adjustment unit performs the phase difference AF process when an exposure value calculated at the time of shooting before the main shooting is greater than or equal to a threshold value, and performs the contrast AF process when the exposure value is less than the threshold value apparatus. The imaging device according to claim 14 or 15,
A 3D shooting mode for shooting and recording a plurality of captured image data with parallax,
In the 3D imaging mode, the driving unit performs the provisional imaging and the main imaging in the second imaging process, and the focus adjustment unit performs the phase difference AF process. An imaging method using the imaging device according to any one of claims 1 to 13,
A driving step of switching between a first imaging process in which imaging is performed in a state where a potential barrier for the charge generation region is formed by the barrier region and a second imaging process in which imaging is performed in a state where the potential barrier is extinguished. When,
A focus adjustment step for performing a focus adjustment process for adjusting the position of a focus lens arranged in front of the image sensor based on a captured image signal obtained by provisional imaging with the image sensor;
The focus adjustment process includes a phase difference AF process for performing focus adjustment by a phase difference detection method based on a captured image signal obtained from the image sensor in the second imaging process,
An imaging method in which, in the driving step, the first imaging process is performed during the main imaging performed after the focus adjustment process. The imaging method according to claim 17,
The focus adjustment process includes a contrast AF process for performing focus adjustment by a contrast detection method based on a captured image signal obtained from the image sensor in the first imaging process,
In the focus adjustment step, the phase difference AF process is performed when an exposure value calculated at the time of photographing before the main photographing is equal to or greater than a threshold value, and the contrast AF process is performed when the exposure value is less than the threshold value. Method. The imaging method according to claim 17 or 18,
An imaging method that performs the provisional imaging and the main imaging in the second imaging process and performs focus adjustment in the phase difference AF process in a 3D imaging mode in which a plurality of captured image data with parallax is captured and recorded.

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