JP5413481B2 - Photoelectric conversion unit connection / separation structure, solid-state imaging device, and imaging apparatus - Google Patents

Description

  The present invention relates to a connecting / separating structure for photoelectric conversion units, and a solid-state imaging device and an imaging apparatus using the same.

  In recent years, imaging devices such as video cameras and electronic still cameras have been widely used. These cameras use a solid-state imaging device such as a CCD type or an amplification type. In these solid-state imaging devices, a plurality of pixels having photoelectric conversion units that generate signal charges according to the amount of incident light are arranged in a matrix.

  In an amplification type solid-state imaging device, signal charges generated and accumulated in a photoelectric conversion unit of a pixel are guided to an amplification unit provided in the pixel, and a signal amplified by the amplification unit is output from the pixel. The amplification type solid-state imaging device includes, for example, a solid-state imaging device using a junction field effect transistor in the amplification unit (Patent Documents 1 and 2), or a CMOS type solid-state imaging device using a MOS transistor in the amplification unit ( Patent Document 3) has been proposed.

  In the conventional solid-state imaging device disclosed in Patent Literatures 1-3, a photoelectric conversion unit and an amplification unit are provided for each pixel, and a charge storage unit that temporarily accumulates charges between them. . In such a conventional solid-state imaging device, after all the pixels are exposed simultaneously, the signal charges generated in each photoelectric conversion unit are transferred to each charge storage unit at the same time, and are accumulated once. Signal charges are sequentially converted into pixel signals at a predetermined readout timing. Accordingly, it is possible to prevent image distortion caused by the exposure accumulation time of each pixel when the electronic shutter operation is performed being shifted for each row (so-called rolling shutter).

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

  Therefore, in recent years, a so-called pupil division phase difference method (sometimes called a pupil division method or a phase difference method) is adopted as a focus detection method, and solid-state imaging configured to be used as a focus detection element. An element has been proposed (for example, Patent Document 4 below). The pupil division phase difference method detects the defocus amount of the photographing lens by forming a pair of divided images by dividing the light beam passing through the photographing lens into pupils and detecting the pattern shift (phase shift amount). is there.

  In the solid-state imaging device disclosed in Patent Document 4, a plurality of pixels each having a photoelectric conversion unit divided into two are provided. A floating diffusion is arranged between one part and the other part of the two-divided photoelectric conversion unit, and the photoelectric conversion unit is divided into two by this floating diffusion. On such a photoelectric conversion unit, microlenses are provided on a one-to-one basis with respect to pixels. The two-divided photoelectric conversion unit is disposed at a position that is substantially image-formed (ie, substantially conjugate) with the exit pupil of the photographing lens by the microlens. Therefore, since the distance between the exit pupil of the photographing lens and the microlens is sufficiently long with respect to the size of the microlens, the two-divided photoelectric conversion unit is disposed on the substantially focal plane of the microlens. It will be. From the relationship described above, in each pixel, one part of the photoelectric conversion unit divided into two is a light beam from a region that is a part of the exit pupil of the photographing lens and decentered in a predetermined direction from the center of the exit pupil. Is selectively received and photoelectrically converted. Further, in each pixel, the other part of the photoelectric conversion unit divided into two is selectively a light beam from a region that is a part of the exit pupil of the photographing lens and decentered in the opposite direction from the center of the exit pupil. Light is received and photoelectrically converted.

  In the solid-state imaging device disclosed in Patent Document 4, at the time of focus detection, the signal of one part and the signal of the other part of the two-divided photoelectric conversion unit of each pixel having the photoelectric conversion unit divided into two are floating at different timings. It is transferred to the diffusion and read out individually. Then, according to the principle of the pupil division phase difference method, the focus adjustment state of the photographing lens is detected based on these signals. On the other hand, when an image is taken after the photographing lens is focused, the signals from both parts of the two-divided photoelectric conversion unit of each pixel are transferred to the same floating diffusion at the same timing, and both signals are transmitted within the pixel. Added and read. Therefore, a pixel having a photoelectric conversion unit divided into two at the time of imaging does not cause a state similar to a pixel defect, which is excellent in terms of improving image quality.

JP-A-11-177076 JP 2004-335882 A JP 2004-111590 A JP 2003-244712 A

  However, in the solid-state imaging device disclosed in Patent Document 4, as described above, a floating diffusion is arranged between one part and the other part of the photoelectric conversion unit divided into two, and the photoelectric conversion unit is formed by this floating diffusion. Is divided into two. For this reason, since there is no light receiving sensitivity in the central part of the pixel where the incident light amount is concentrated, there is a problem that the sensitivity is lowered when the pixel is used for imaging at the time of imaging.

  The present invention has been made in view of such circumstances. While focus detection is possible, the present invention does not cause a state similar to a pixel defect at the time of imaging and suppresses a decrease in sensitivity at the time of imaging. An object of the present invention is to provide a solid-state imaging device capable of performing imaging and an imaging apparatus using the same.

  Another object of the present invention is to provide a photoelectric conversion unit connection / separation structure that can be used in such a solid-state imaging device.

  Here, the following aspects are presented as technical means for solving the above problems and technical means related thereto.

  A solid-state imaging device according to a first aspect is a solid-state imaging device that photoelectrically converts a subject image formed by an optical system, and includes a plurality of pixels arranged in a two-dimensional shape, At least some of the pixels exist in one side region and the other side region divided by the dividing line in plan view, respectively, and one side photoelectric conversion unit and the other side photoelectric conversion unit that photoelectrically convert incident light, respectively. And mode setting means that can set the first mode and the second mode in accordance with a control signal, respectively, wherein the first mode includes a photoelectric conversion unit on the one side and a photoelectric conversion unit on the other side. The second mode is a mode in which the photoelectric conversion unit on the one side and the photoelectric conversion unit on the other side are electrically separated from each other, and the photoelectric conversion on the one side is performed. Part and the photoelectric conversion part on the other side Area, while having a function of photoelectric conversion of incident light in the first mode, in which no function of photoelectric conversion of incident light in the second mode.

  In the solid-state imaging device according to the second aspect, in the first aspect, the mode setting means includes a gate electrode arranged along the dividing line.

  The solid-state imaging device according to a third aspect of the present invention is the solid-state imaging device according to the second aspect, wherein the gate electrode includes a semiconductor region of the photoelectric conversion unit on one side and a semiconductor region of the other photoelectric conversion unit as a source / drain. This constitutes the gate of the MOS transistor.

  In the solid-state imaging device according to a fourth aspect, in the second or third aspect, the gate electrode extends into a region between opposed end surfaces of the photoelectric conversion unit on the one side and the photoelectric conversion unit on the other side. It is not.

The solid-state imaging device according to a fifth aspect is the solid-state imaging device according to the second or third aspect, wherein the gate electrode advances into a region between opposed end surfaces of the one side photoelectric conversion unit and the other side photoelectric conversion unit. In the solid-state imaging device according to the sixth aspect, in any one of the second to fifth aspects, the gate electrode is transparent to at least a part of the visible wavelength range. It is comprised with the material which has property.

  The solid-state imaging device according to a seventh aspect is the solid-state imaging device according to the sixth aspect, wherein the gate electrode is made of ITO or polysilicon.

  The solid-state imaging device according to an eighth aspect is the one-to-one photoelectric conversion unit provided on the one side of each of the at least some of the pixels in any one of the first to seventh aspects. And a microlens for guiding incident light to the photoelectric conversion unit on the other side.

  A solid-state imaging device according to a ninth aspect is obtained in the second mode from the solid-state imaging device according to any one of the first to eighth aspects and each selected pixel of the at least some pixels. A detection processing unit that outputs a detection signal indicating a focus adjustment state of the optical system based on the received signal, and an adjustment unit that performs focus adjustment of the optical system based on the detection signal from the detection processing unit. An imaging apparatus characterized by that.

  The connection / separation structure of the photoelectric conversion units according to the tenth aspect exists in one side region and the other side region that are divided by the dividing line in plan view, and each one photoelectric conversion that photoelectrically converts incident light. And a photoelectric conversion unit on the other side, and mode setting means that can be set to the first and second modes according to a control signal, respectively, wherein the first mode includes the photoelectric conversion unit on the one side and the photoelectric conversion unit The second photoelectric conversion unit is a mode in which the photoelectric conversion unit on the other side is electrically connected, and the second mode is a mode in which the photoelectric conversion unit on the one side and the photoelectric conversion unit on the other side are electrically separated. And a region between the photoelectric conversion unit on the one side and the photoelectric conversion unit on the other side has a function of photoelectrically converting incident light in the first mode, while incident light is converted in the second mode. It does not have a photoelectric conversion function That.

  According to the present invention, there is provided a solid-state imaging device capable of detecting a focus, causing no state similar to a pixel defect at the time of imaging, and suppressing a decrease in sensitivity at the time of imaging, and The used imaging device can be provided.

  Further, according to the present invention, it is possible to provide a photoelectric conversion unit connection / separation structure that can be used for such a solid-state imaging device.

1 is a schematic block diagram showing an electronic camera according to a first embodiment of the present invention. It is a circuit diagram which shows schematic structure of the solid-state image sensor in FIG. It is a schematic plan view which shows typically the solid-state image sensor in FIG. FIG. 4 is a schematic enlarged view in which the vicinity of a predetermined focus detection region in FIG. 3 is enlarged. FIG. 4 is a schematic enlarged view in which the vicinity of another focus detection region in FIG. 3 is enlarged. It is a circuit diagram which shows the predetermined pixel of the solid-state image sensor in FIG. It is a schematic plan view which shows typically the predetermined pixel of the solid-state image sensor in FIG. FIG. 8 is a schematic cross-sectional view along the line A-A ′ in FIG. 7. It is a schematic sectional drawing in alignment with the B-B 'line in FIG. 7 which shows a predetermined operation state. It is a schematic sectional drawing in alignment with the B-B 'line in FIG. 7 which shows another operation state. FIG. 2 is a schematic plan view schematically showing main elements of predetermined pixels of the solid-state imaging device in FIG. 1. It is a schematic plan view which shows typically the main elements of the other pixel of the solid-state image sensor in FIG. It is a circuit diagram which shows the other pixel of the solid-state image sensor in FIG. It is a schematic plan view which shows typically the main elements of the other pixel of the solid-state image sensor in FIG. 2 is a timing chart illustrating an operation example of the solid-state imaging device in FIG. 1. 6 is a timing chart illustrating another operation example of the solid-state imaging device in FIG. 1. It is a schematic plan view which shows typically the solid-state image sensor of the electronic camera by the 2nd Embodiment of this invention. It is the schematic enlarged view to which the arbitrary area | regions of the imaging area in FIG. 17 were expanded. It is a schematic flowchart which shows operation | movement of the electronic camera by 2nd Embodiment. It is a schematic plan view which shows typically the solid-state image sensor of the electronic camera by the 3rd Embodiment of this invention. FIG. 21 is a schematic enlarged view in which the vicinity of the focus detection region in FIG. 20 is enlarged. It is a schematic plan view which expands and schematically shows an arbitrary part of an imaging region of a solid-state imaging device of an electronic camera according to a fourth embodiment of the present invention. It is a schematic sectional drawing which shows the pixel by a 1st modification. It is a schematic sectional drawing which shows the pixel by a 2nd modification.

  Hereinafter, a connection / separation structure of photoelectric conversion units according to the present invention, and a solid-state imaging device and an imaging apparatus using the same will be described with reference to the drawings.

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

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

  FIG. 2 is a circuit diagram showing a schematic configuration of the solid-state imaging device 3 in FIG. The solid-state imaging device 3 includes a plurality of pixels 20 arranged in a matrix and a peripheral circuit for outputting a signal from the pixels 20. An imaging region in which the pixels 20 are arranged in a matrix is indicated by reference numeral 31. In FIG. 2, the number of pixels indicates 16 pixels of 4 rows horizontally and 4 rows vertically. However, in the present embodiment, the number of pixels is much larger than that. However, in the present invention, the number of pixels is not particularly limited. In the present embodiment, the solid-state imaging device 3 has three types of pixels 20V, 20H, and 20N, which will be described later, as pixels, but in FIG. Show. The specific circuit configuration and structure will be described later. These pixels 20 output imaging signals or focus detection signals in accordance with peripheral circuit drive signals. Further, the exposure time and timing of all the pixels 20 can be made the same by simultaneously resetting the photoelectric conversion unit.

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

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

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

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

  FIG. 4 is a schematic enlarged view in which the vicinity of the focus detection region 35 in FIG. 3 is enlarged, and schematically shows the pixel arrangement. FIG. 5 is a schematic enlarged view in which the vicinity of the focus detection area 36 in FIG. 3 is enlarged, and schematically shows the pixel arrangement. As described above, the solid-state imaging device 3 has the three types of pixels 20V, 20H, and 20N classified as the pixel 20 from the viewpoint of the presence / absence / division direction of the photoelectric conversion unit. 4 and 5, the pixels 20 </ b> V, 20 </ b> H, and 20 </ b> N are denoted by “V”, “H”, and “N”, respectively. When configured for color, the color filter color of each pixel 20 is set so as to realize, for example, a Bayer array. However, in the present invention, it may be configured for black and white.

  The focus detection area 35 extending in the Y-axis direction is a part of a column in the Y-axis direction in which the pixels 20V are arranged as shown in FIG. The focus detection areas 33 and 34 extending in the Y-axis direction are the same as the focus detection area 35. As shown in FIG. 5, the focus detection area 36 extending in the X-axis direction is a part of a row in the X-axis direction in which the pixels 20H are arranged. The focus detection areas 32 and 37 extending in the X-axis direction are the same as the focus detection area 36.

  FIG. 6 is a circuit diagram illustrating the pixels 20V and 20H (see FIGS. 4 and 5) of the solid-state imaging device 3 in FIG. These pixels 20V and 20H have the same circuit configuration.

  Each of the pixels 20V and 20H independently includes two embedded photodiodes 41 and 42 as two photoelectric conversion units that generate and store charges according to incident light, and charges transferred from the embedded photodiodes 41 and 42, respectively. First and second charge storage units 43 and 44, and first and second transfer for transferring charges from the respective embedded photodiodes 41 and 42 to the first and second charge storage units 43 and 44, respectively. First and second transfer transistors 45 and 46 as a part, a floating diffusion region (FD) 47 as a predetermined part, and a first part that transfers charges from the first and second charge storage parts 43 and 44 to the FD 47, respectively. The third and fourth transfer transistors 48 and 49 as the third and fourth transfer gate units, and the amplifier unit that outputs a signal corresponding to the charge amount of the FD 47 A width transistor 50, an FD reset transistor 51 as a first reset unit that discharges the electric charge of the FD 47, a selection transistor 52 as a selection switch that outputs a signal of the amplification transistor 50 from the pixels 20V and 20H, and an embedded photodiode First and second PD reset transistors 53, which serve as second and third reset units (charge discharge gate units) for discharging charges (unnecessary charges generated by the embedded photodiodes 41, 42), respectively, from 41, 42. 54. Each of the pixels 20V and 20H has a connection / separation transistor 55 that performs electrical connection and separation between the embedded photodiodes 41 and 42.

  The first to fourth transfer transistors 45, 46, 48, and 49, the amplification transistor 50, the FD reset transistor 51, the selection transistor 52, the first and second PD reset transistors 53 and 54, and the connection / separation transistor 55 are any Is also composed of MOS transistors. In this embodiment, these transistors (excluding the amplification transistor 50) are turned on when the gate electrode is high, and turned off when the gate electrode is low (exemplified by an N-channel MOS transistor).

  The gate electrodes of the connection / separation transistors 55 are connected in common to each pixel row, and a drive signal (control signal) φPDB is supplied from the vertical scanning circuit 21 via the drive wiring 23. In the present embodiment, if φPDB is high, the connection / separation transistor 55 is turned on, and the embedded photodiodes 41 and 42 are electrically connected. As a result, the embedded photodiodes 41 and 42 are substantially equivalent to one undivided photoelectric conversion unit as a whole. In the following description, this state is referred to as a “PD united state”. On the other hand, if φPDB is low, the connection / separation transistor 55 is turned off, and the embedded photodiodes 41 and 42 are electrically separated. As a result, the embedded photodiodes 41 and 42 are divided into two. In the following description, this state is referred to as “PD2 division state”.

  In the present embodiment, first and second charge storage units 43 and 44 are provided, and the charge generated by the embedded photodiodes 41 and 42 is stored in the first and second charge storages before being transferred to the FD 47. Each of the units 43 and 44 is temporarily stored. This makes it possible to make the exposure times and timings of all the pixels the same, and not only the simultaneity of the image signals but also the simultaneity of the signals at the time of focus detection. However, in the present invention, a rolling shutter may be performed without providing the charge storage units 43 and 44. In this case, simultaneity is maintained in the horizontal direction (H pixel), but simultaneity is not maintained in the vertical direction (V pixel).

  The first transfer transistor 45 transfers charges from the embedded photodiode 41 to the first charge storage unit 43. The second transfer transistor 46 transfers the charge from the embedded photodiode 42 to the second charge storage unit 44.

  The gate electrodes of the first and second transfer transistors 45 and 46 are connected in common and further connected in common for each pixel row, and a drive signal φTGA is supplied from the vertical scanning circuit 21 through the drive wiring 23. The first and second transfer transistors 45 and 46 are simultaneously turned on at a predetermined timing in accordance with the drive signal φTGA, and charges are transferred from the two embedded photodiodes 41 and 42 to the charge storage units 43 and 44 at the same time. To do. However, the present invention is not limited to this. For example, a drive signal may be individually supplied to each gate electrode so that the first and second transfer transistors 45 and 46 are turned on simultaneously. Absent.

  On the other hand, separate drive signals are supplied to the gate electrodes of the third and fourth transfer transistors 48 and 49, respectively. That is, the gate electrode of the third transfer transistor 48 is commonly connected to each pixel row, and the drive signal φTGB is supplied from the vertical scanning circuit 21 via the drive wiring 23. The gate electrode of the fourth transfer transistor 49 is A drive signal φTGC is supplied from the vertical scanning circuit 21 through the drive wiring 23 in common connection for each pixel row. The third and fourth transfer transistors 48 and 49 are individually turned on at a predetermined timing in accordance with the drive signals φTGB and φTGC, and charges are transferred from the first and second charge storage units 43 and 44 at individual timings. Alternatively, the data is transferred to the FD 47 at the same timing.

  The gate electrodes of the selection transistors 52 are commonly connected to each pixel row, and the drive signal φS is supplied from the vertical scanning circuit 21 via the drive wiring 23. The gate electrode of the FD reset transistor 51 is commonly connected to each pixel row, and the drive signal φFDR is supplied from the vertical scanning circuit 21 through the drive wiring 23. Further, the gate electrodes of the PD reset transistors 53 and 54 are connected in common and further connected to each pixel row in common, and the drive signal φPDR is supplied from the vertical scanning circuit 21 through the drive wiring 23. However, the PD reset transistors 53 and 54 (in the case of the pixel 20N, the PD reset transistor 153 in FIG. 13 to be described later) are connected in common to all effective pixels, so that the PD reset of all effective pixels is performed. The transistors 53 and 54 (however, in the case of the pixel 20N, a PD reset transistor 153 in FIG. 13 to be described later) may be simultaneously turned on and off.

  In FIG. 6, one terminal of the embedded photodiodes 41 and 42, one terminal of the charge storage units 43 and 44, and one terminal of the FD 47 are described as ground for convenience. However, in actuality, the potential of the P-type well 61 is as understood from FIGS. 8 to 10 described later.

  FIG. 7 is a schematic plan view schematically showing the pixel 20V. FIG. 8 is a schematic cross-sectional view along the line A-A ′ in FIG. 7. 9 and 10 are schematic cross-sectional views along the line B-B 'in FIG. FIG. 9 shows a state in which the connection / separation transistor 55 is turned off by setting the gate electrode 67 to low (that is, φPDB to low). FIG. 10 shows a state in which the connection / separation transistor 55 is turned on with the gate electrode 67 high (that is, φPDB is high). 8 to 10, the micro lens 65 is omitted. 7 to 10, the drive wiring is omitted, and the wiring shows only the electrical connection relationship in the pixel 20V.

  As shown in FIGS. 8 to 10, a P-type well 62 is provided on an N-type silicon substrate 61. Then, an N-type charge storage layer 63 is formed in the P-type well 62, and a P-type depletion prevention layer 64 is further added to the substrate surface side of the charge storage layer 63, whereby the embedded photodiodes 41 and 42 are configured. Has been. Here, the structure of the embedded photodiode is adopted, but the structure is not limited to this, and the depletion preventing layer 64 may be omitted.

  As shown in FIG. 7, the two embedded photodiodes 41, 42 are a + Y side region and a −Y side region that are divided by a dividing line CC ′ in the X axis direction in a plan view as viewed from the Z axis direction. Are arranged respectively. As shown in FIG. 7, one microlens 65 that guides incident light to the embedded photodiodes 41 and 42 is disposed. The microlens 65 is disposed so that the optical axis O passes through the intersection of the dividing line C-C ′ and the center line of the embedded photodiodes 41 and 42 in the X-axis direction. Therefore, the incident light guided from the microlens 65 is divided into pupils and is incident on the embedded photodiodes 41 and 42. In order to reduce shading, for example, in the central pixel of the effective pixel region, the microlens 65 is arranged so that the optical axis O passes through the intersection point, while in the peripheral pixel of the effective pixel region, The micro lens 65 may be arranged so that its optical axis O passes through a position shifted from the intersection point.

  As shown in FIGS. 7, 9 and 10, the gate electrode 67 is provided along the dividing line C-C ′. The gate electrode 67 is formed between the embedded photodiodes 41 and 42 via a thin silicon oxide film 66. As a result, the gate electrode 67 constitutes the gate of a MOS transistor (coupled / separated transistor 55) that uses the charge storage layer 63 of the embedded photodiode 41 and the charge storage layer 63 of the embedded photodiode 42 as the source / drain. The drive signal φPDB is supplied to the gate electrode 67 by a wiring (not shown).

  In this embodiment, if the gate electrode 67 is low (if φPDB is low), an inversion layer cannot be formed in the channel region of the connection / separation transistor 55 as shown in FIG. Turn off. On the other hand, if the gate electrode 67 is high (if φPDB is high), an inversion layer 69 is formed in the channel region of the connection / separation transistor 55, and the connection / separation transistor 55 is turned on.

  The connection / separation transistor 55 may be configured to turn off when its gate potential is set to zero potential (substrate 61 potential), and to be turned on when a potential having a large difference from the zero potential is applied. Good. The connection / separation transistor 55 is configured to turn on when the gate potential is set to zero potential (the potential of the substrate 61), and to be turned off when a negative potential is applied to the zero potential. Also good. When the gate / voltage is not applied, the connecting / separating transistor 55 is turned on when the gate voltage is applied to the positive side, and the gate / voltage is not applied. When turned on, the gate voltage is applied to the negative side to turn off.

  In the present embodiment, the gate electrode 67 is made of a material having translucency with respect to at least a part of the visible wavelength range, such as an ITO film. Accordingly, the incident light reaches the region between the embedded photodiodes 41 and 42 under the gate electrode 67 without being blocked by the gate electrode 67. Therefore, for example, if the coupling / separation transistor 55 is turned on as shown in FIG. 10, the inversion layer 69 formed between the embedded photodiodes 41 and 42 has a photoelectric conversion function. Rise. On the other hand, if the coupling / separation transistor 55 is off as shown in FIG. 9, the inversion layer 69 cannot be formed, and the region between the embedded photodiodes 41 and 42 does not have a photoelectric conversion function.

  The gate electrode 67 may be made of polysilicon, for example, instead of the ITO film. In the case of polysilicon, the transmittance is partially reduced as compared with the ITO film, but since it is easy to form a fine structure, the amount of light loss can be reduced more in the case of polysilicon in a comprehensive view. There is also.

  As can be seen from the above description, in this embodiment, the gate electrode 67 is set to the PD combined state (first mode) and the PD2 divided state (second mode) in accordance with the control signal (φPDB). The mode setting means which can do is comprised. In the PD2 division state, the signals of the embedded photodiodes 41 and 42 are obtained independently of each other. In the PD combined state, the signals of the embedded photodiodes 41 and 42 are added.

  A gate electrode 71 is formed on the space between the first and second charge storage portions 43 and 44 and the embedded photodiodes 41 and 42 via a thin silicon oxide film 66, respectively. Each of the first and second transfer transistors 45 and 46 is a MOS transistor having the gate electrode 71 as a gate and the charge storage portions 43 and 44 and the charge storage layer 63 of the embedded photodiodes 41 and 42 as a source or a drain. It is configured as.

  The gate electrode of the first transfer transistor 45 and the gate electrode of the second transfer transistor 46 are integrally formed to form a gate electrode 71. For this reason, the first and second transfer transistors 45 and 46 are simultaneously turned on and off according to the drive signal φTGA. Accordingly, the charges from the embedded photodiodes 41 and 42 are simultaneously transferred to the corresponding charge storage units 43 and 44, respectively.

  The charge storage units 43 and 44 have N-type layers 73 and 74 formed in the P-type well 62. The gate electrodes 71 of the first and second transfer transistors 45 and 46 are arranged so as to cover the upper portions of the two N-type layers 73 and 74. The charge storage portions 43 and 44 are configured as MOS capacitors by the gate electrode 71 and the N-type layers 73 and 74 as described above.

  By the way, when a low voltage is applied to the gate electrode 71, it is pinned to the potential of the P-type well 62 and the interface states on the surfaces of the charge storage portions 43 and 44 are filled with holes. The magnitude of the dark current is greatly influenced by the electron occupation probability of the interface state. Therefore, the dark current in the charge storage portions 43 and 44 can be greatly reduced by applying the voltage as described above to the gate electrode 71 to fill the interface state with holes.

  In FIG. 7, the FD 47 is configured substantially as one floating diffusion by electrically connecting two N-type regions 75 and 76 formed in the P-type well 32 separately from each other through a wiring 77. . Charge is transferred from the two charge storage units 43 and 44 to the FD 47. In addition, charge storage portions 43 and 44 are disposed between the N-type region 75 of the FD 47 and the embedded photodiodes 41 and 42. With this arrangement, the charge transfer direction is one direction (here, the X-axis direction), and an afterimage is less likely to occur.

  Gate electrodes 78 and 79 are formed between the first and second charge storage portions 43 and 44 and the N-type diffusion layer 75 of the FD 47 with a thin silicon oxide film 66 interposed therebetween. The third and fourth transfer transistors 48 and 49 have the gate electrodes 78 and 79 as gates and the N-type layers 73 and 74 of the charge storage portions 43 and 44 and the N-type diffusion region 75 of the FD 47 as sources or drains. It is configured as a MOS transistor.

  The gate electrode 78 of the third transfer transistor 48 and the gate electrode 79 of the fourth transfer transistor 49 are individually formed, and individual drive signals φTGB and φTGC are supplied from the vertical scanning circuit 21, respectively. Therefore, the third and fourth transfer transistors 48 and 49 are individually driven according to the respective drive signals φTGB and φTGC. Therefore, the third and fourth transfer transistors 48 and 49 can transfer charges from the first and second charge storage units 43 and 44 to the FD 47 at different timings or at the same timing.

  In addition, as shown in FIG. 7, N-type diffusion layers 81-83 are formed in the P-type well 62. The N-type layer 81 is connected to the power supply VDD by a wiring (not shown). A gate electrode 84 is formed between the N-type layers 81 and 82 via a thin silicon oxide film 66. The amplification transistor 50 is configured as a MOS transistor having the gate electrode 84 as a gate and the N-type layers 81 and 82 as sources or drains. Note that the gate electrode 84 is electrically connected to the FD 47 (N-type layers 75 and 76) by a wiring 77.

  A gate electrode 85 is formed between the N-type layers 82 and 83 via a thin silicon oxide film 66. The selection transistor 52 is configured as a MOS transistor having the gate electrode 85 as a gate and the N-type layers 82 and 83 as sources or drains.

  A gate electrode 86 is formed between the N-type layers 76 and 81 via a thin silicon oxide film 66. The FD reset transistor 51 is configured as a MOS transistor having the gate electrode 86 as a gate and the N-type layers 76 and 81 as sources or drains.

  As shown in FIGS. 7 and 8, an N-type layer 87 is formed in the P-type well 62. Gate electrodes 88 and 89 are formed between the N-type layer 87 and the buried photodiodes 41 and 42 through a thin silicon oxide film 66. The first PD reset transistor 53 is configured as a MOS transistor having the gate electrode 88 as a gate and the N-type layer 87 and the charge storage layer 63 of the embedded photodiode 41 as a source or drain. The second PD reset transistor 54 is configured as a MOS transistor having the gate electrode 89 as a gate and the N-type layer 87 and the charge storage layer 63 of the embedded photodiode 42 as a source or drain. The gate electrodes 88 and 89 are connected to each other by a wiring 100, and a drive signal φPDR is supplied by a wiring (not shown). Here, the two gate electrodes 88 and 89 are connected by the wiring 100, but the two gate electrodes 88 and 89 may be integrally formed.

  The second reset unit (here, PD reset transistors 53 and 54) discharges unnecessary charges generated by the embedded photodiodes 41 and 42. This unnecessary charge includes a reset charge when the electronic shutter operation is performed and an overflow charge when a strong light is incident. In any case, this unnecessary charge may be transferred to the FD 47 and discharged by the first reset unit (here, the FD reset transistor 51). If it does in this way, the 2nd reset part does not need to be arrange | positioned.

  Further, a thick silicon oxide film 70 is formed around the embedded photodiodes 41 and 42 and the N-type layers, and the respective portions are separated from each other.

  The configuration of the pixel 20V (see FIG. 4) of the solid-state image sensor 3 in FIG. 1 has been described above. In the pixel 20V, the positional relationship in plan view of the microlens 65, the embedded photodiodes 41 and 42, and the gate electrode 67 described above is more abstract than FIG. 7 as shown in FIG.

  Next, the pixel 20H (see FIG. 5) of the solid-state imaging device 3 in FIG. 1 will be described. FIG. 12 is a diagram illustrating a positional relationship in a plan view of the microlens 65, the embedded photodiodes 41 and 42, and the gate electrode 67 in the pixel 20H, and corresponds to FIG. 12, elements that are the same as or correspond to those in FIG. 11 are given the same reference numerals, and redundant descriptions thereof are omitted.

  The pixel 20H differs from the pixel 20V in that, in the pixel 20V, the embedded photodiodes 41 and 42 are respectively on the + Y side and the −Y side with respect to the gate electrode 67 arranged along the dividing line extending in the X-axis direction. In contrast, in the pixel 20H, the embedded photodiodes 41 and 42 are respectively disposed on the −X side and the + X side with respect to the gate electrode 67 disposed along the dividing line extending in the Y-axis direction. In connection with this, although not shown in the drawing, only the arrangement of the transistors and the like is changed.

  Therefore, in the pixel 20V, the embedded photodiode 41 selectively receives the light beam from the exit pupil region decentered to the −Y side from the center of the exit pupil of the photographing lens 2, and the embedded photodiode 42 A light beam from the exit pupil region decentered toward the + Y side from the center of the exit pupil of the photographing lens 2 is selectively received effectively. On the other hand, in the pixel 20H, the embedded photodiode 41 selectively receives light from the exit pupil region decentered toward the + X side from the center of the exit pupil of the photographing lens 2, and the embedded photodiode 42 The light beam from the exit pupil region decentered to the −X side from the center of the exit pupil of the photographing lens 2 is selectively received effectively.

  Next, the pixel 20N (see FIGS. 4 and 5) of the solid-state imaging device 3 in FIG. 1 will be described. FIG. 13 is a circuit diagram showing the pixel 20N. FIG. 14 is a diagram illustrating a positional relationship in a plan view of the microlens 65 and the embedded photodiode 141 in the pixel 20N, and corresponds to FIG. 13 and 14, the same or corresponding elements as those in FIGS. 6 and 11 are denoted by the same reference numerals, and redundant description thereof is omitted.

  The pixel 20N has one embedded photodiode 141 formed by removing the gate electrode 67 in FIG. 6 and integrally forming embedded photodiodes 41 and. Accordingly, the pixel 20N includes one charge storage unit 143 corresponding to the first and second charge storage units 43 and 44 in FIG. 6, and the first and second transfer transistors 45 and 46 in FIG. And one transfer transistor 148 corresponding to the third and fourth transfer transistors 48 and 49 in FIG. As can be seen from the above description, the pixel 20N has the same structure as a pixel of a conventional general solid-state imaging device.

  Next, an example of an operation for reading a signal from the solid-state imaging device 3 will be described with reference to FIGS. 15 and 16. FIG. 15 is a timing chart showing a driving signal for reading out an imaging signal (that is, a driving signal for reading out a signal from a pixel exposed in the PD combined state). FIG. 16 is a timing chart showing a drive signal for reading out a focus detection signal from a pixel exposed in the PD2 division state.

  For vertical scanning, a signal line is selected for each horizontal line, and the selection operation is sequentially shifted to the next row. As shown in FIGS. 15 and 16 for each selected row. The operation is performed, and the drive signal of this figure is output. This scanning is repeated over the entire vertical screen. After finishing the last row, the selection operation returns to the first row after the vertical blanking period. 15 and FIG. 16, only the drive signals in the first and second rows are shown.

  First, an example of an operation for reading an imaging signal will be described with reference to FIGS. 15, 2, 6, and 13. In this operation, basically, all the pixels 20V and 20H except for the pixel 20N among all the effective pixels 20 at the time of exposure are brought into the PD combined state. In this operation, all pixels are simultaneously exposed.

  In FIG. 15, a period T1 is a period in which all effective pixels are driven simultaneously. That is, the same drive signal is output in all rows for the drive pulse in the period T1. Further, the period T2 is a period for reading the first row, the period T3 is a period for reading the second row, and the period T4 is a period for reading the third row. Only the selected row outputs a drive signal as shown in FIG. The This also applies to FIG. 16 described later.

  First, in a period from the start time of the period T11 to the end time of the period T14, φPDB is set high, and all the pixels 20V and 20H except for the pixel 20N among all the effective pixels 20 are set in the PD combined state. Therefore, the embedded photodiodes 41 and 42 of the pixels 20V and 20H are substantially equivalent to one undivided photoelectric conversion unit as a whole. During this period, operations in periods T11 to T14 described below are performed.

  First, in period T11, φPDR is set high to turn on PD reset transistors 53, 54, and 153. With this operation, unnecessary charges stored in the embedded photodiodes 41, 42, and 141 of all effective pixels are discharged to the power supply VDD. That is, the embedded photodiodes 41, 42, and 141 are reset. Then, the embedded photodiodes 41, 42, and 141 of all effective pixels start exposure from the end of the period T11. At this time, in this embodiment, as described above, the photoelectric conversion of the incident light is also performed in the region between the embedded photodiodes 41 and 42. For this reason, the sensitivity at the time of imaging improves.

  In a period T12, φFDR is set high to turn on the FD reset transistor 51. At the same time, in the period T13, φTGB and φTGC are set high to turn on the transfer transistors 48, 49, and 148 simultaneously. With this operation, the charges stored in the FD 47 and the charge storage units 43, 44, and 143 are discharged to the power supply VDD. That is, the FD 47 and the charge storage units 43, 44, and 143 of all effective pixels are reset.

  In a period T14, φTGA is set to high to turn on the transfer transistors 45, 46, and 145. The embedded photodiodes 41 and 42 connected to all the pixels 20V and 20H among all the effective pixels and the charges accumulated therebetween are all transferred to the charge storage units 43 and 44. Further, the charges accumulated in the embedded photodiodes 141 of all the pixels 20N among all the effective pixels are transferred to the charge storage unit 143. In the period T14, only one of the first and second transfer transistors 45 and 46 may be turned on. Here, the period T15 shown in FIG. 15 (the period from when φPDR is set low to when φTGA is turned on) is the exposure period. The exposure period T15 is the same period and the same timing for all effective pixels. For this reason, all effective pixels can acquire image information without a timing shift.

  Next, in a period T <b> 16, φS in the first row is set high to turn on the selection transistor 52. As a result, the pixels in the first row are selected, and a signal is output from the pixels in the first row to the vertical signal line 25.

  At the same time, in period T17, φFDR in the first row is set high to turn on the FD reset transistor 51. With this operation, the FD 47 is reset. The output at the time of FD47 reset from the amplification transistor 50 in the first row is the vertical signal from the end of the period T17, that is, from when φFDR becomes low until the start of the period T19 (period T18). It is stored in the CDS circuit 27 via the line 25.

  In a period T19, φTGB and φTGC are set high to turn on the transfer transistors 48, 49, and 148 simultaneously. As a result, the charges accumulated in the two charge storage units 43 and 44 in each of the pixels 20V and 20H are added together and transferred to the FD 47. In addition, the charge accumulated in the charge storage unit 143 of each pixel 20N is transferred to the FD 47. Then, the potential amplified according to the charge amount of the FD 40 is sent to the CDS circuit 27 through the vertical signal line 25. The CDS circuit 27 outputs the difference from the reset output stored earlier as the pixel signal of the pixels in the first row. The pixel signals of the pixels in the first row are output via the horizontal signal line 28 and the output amplifier 29 by the drive signal of the horizontal scanning circuit 22.

  Similarly, reading of the second row is performed in the period T3. The drive signal is the same as in the first row. Periods T26 to T29 in FIG. 9 correspond to periods T16 to T19.

  Note that φPDR may always be high after the end of reading (after φS is turned off).

  As understood from the above description, each of the pixels 20V and 20H combines the two embedded photodiodes 41 and 42 with φPDB being high during the period from the start time of the period T11 to the end time of the period T14. Therefore, as in the case of the pixel 20N, the imaging signal can be output as usual. In addition, since the gate electrode 67 disposed along the dividing line transmits incident light, the utilization efficiency of incident light is increased and the sensitivity can be improved. Further, it is clear from the above description that an electronic shutter with the same exposure timing for all effective pixels is possible. Of course, it is possible to perform a rolling shutter operation that is reset for each row regardless of the presence or absence of the charge storage units 43 and 44.

  Next, an example of an operation for reading out focus detection signals from the pixels 20V and 20H exposed in the PD2 division state will be described with reference to FIGS. In this operation example, basically, all pixels 20V and 20H are set in the PD2 division state during exposure. In this operation, all pixels are simultaneously exposed. In addition, since the signal obtained from the pixel 20N when reading the focus detection signal is not used as the focus detection signal, only the pixels 20V and 20H will be described in the following description.

  The signals of all the pixels read out by this operation are temporarily stored in the memory 7 in FIG. 1, and then, when performing the focus detection process in the focus calculation unit 10, the desired pixels are obtained from the signals in the memory 7. Only those related to columns are selectively used. In the operation example shown in FIG. 16, the focus detection signal is obtained by reading all the pixels as described above. However, the pixels other than the pixels in the desired pixel column need not be thinned and the reading operation need not be performed.

  First, in period T31, φPDR is set high to turn on the PD reset transistor 51, and φPDB is set high to establish a PD merge state. With this operation, unnecessary charges stored in the embedded photodiodes 41 and 42 of all the pixels 20V and 20H are discharged to the power supply VDD. That is, the embedded photodiodes 41 and 42 are reset. All of the embedded photodiodes 41 and 42 start exposure from the end of the period T31.

  φPDB remains low during period T1. Therefore, also in the period T35, all the pixels 20V and 20H are in the PD2 division state, and the embedded photodiodes 41 and 42 of the pixels 20V and 20H are substantially equivalent to the photoelectric conversion unit divided into two as a whole. . During this period, operations in periods T32 to T34 described below are performed.

  In a period T32, φFDR is set high to turn on the FD reset transistor 51. At the same time, in the period T33, φTGB and φTGC are set high to turn on the third and fourth transfer transistors 48 and 49 simultaneously. With this operation, the charges stored in the FD 47 and the first and second charge storage units 43 and 44 are discharged to the power supply VDD. That is, the FDs 47 and the charge storage units 43 and 44 of all the pixels 20V and 20H are reset.

  In a period T34, φTGA is set high to turn on the first and second transfer transistors 45 and 46. As a result, the charges accumulated in the embedded photodiodes 41 and 42 of all the pixels 20V and 20H pass through the first and second transfer transistors 45 and 46, respectively, and the first and second charge storage units 43. , 44 respectively. Here, a period T35 shown in FIG. 16 (a period from when φPDR is turned low to when φTGA is turned on) is an exposure period. The exposure period T35 is the same period and has the same timing for all the pixels 20V and 20H. For this reason, all the pixels 20V and 20H can acquire the focus detection information without timing deviation. The operation so far (period T1) is the same as the operation for obtaining the imaging signal described with reference to FIG. 15 except that exposure is performed in the PD2 division state.

  Next, in a period T36, φS in the first row is set high to turn on the selection transistor 52. As a result, the pixels in the first row are selected, and a signal is output from the pixels in the first row to the vertical signal line 25.

  At the same time, in period T37, φFDR in the first row is set high to turn on the FD reset transistor 51. With this operation, the FD 47 is reset. The output at the time of FD47 reset from the amplification transistor 50 in the first row is the vertical signal from the end of the period T37, that is, from when φFDR becomes low to the start of the period T39 (period T38). It is stored in the CDS circuit 27 via the line 25.

  In a period T39, φTGB is set high to turn on the third transfer transistor 48. As a result, the charges accumulated in the first charge storage 43 are transferred to the FD 47. Then, the potential amplified according to the charge amount of the FD 47 is sent to the CDS circuit 27 through the vertical signal line 25. The CDS circuit 27 outputs the difference from the reset output stored earlier as a pupil signal output on one side of the pixels in the first row in the vertical direction or the horizontal direction. Then, the pupil signal output on one side of the pixels in the first row in the vertical direction or the horizontal direction is output via the horizontal signal line 28 and the output amplifier 29 by the drive signal of the horizontal scanning circuit 22.

  Next, in period T40, φFDR in the first row is set high to turn on the FD reset transistor 51. With this operation, the FD 47 is reset. The output at the time of FD47 reset from the amplification transistor 50 in the first row is the vertical signal from the end of the period T40, that is, from when φFDR becomes low until the start of the period T42 (period T41). It is stored in the CDS circuit 27 via the line 25.

  In a period T42, φTGC is set high to turn on the fourth transfer transistor 49. As a result, the charge accumulated in the second charge storage 44 is transferred to the FD 47. Then, the potential amplified according to the charge amount of the FD 47 is sent to the CDS circuit 27 through the vertical signal line 25. The CDS circuit 27 outputs the difference from the reset output stored earlier as the pupil signal output on the other side in the vertical direction or the horizontal direction of the pixels in the first row. Then, the pupil signal output on the other side of the pixels in the first row in the vertical direction or the horizontal direction is output via the horizontal signal line 28 and the output amplifier 29 by the drive signal of the horizontal scanning circuit 22.

  With these operations, it is possible to obtain a pupil signal output on one side of the pixels in the first row in the vertical direction or the horizontal direction and a pupil signal output on the opposite side in the vertical direction or the horizontal direction. Note that whether the pixel is the vertical direction or the horizontal direction depends on whether the pixel is the pixel 20V or the pixel 20H.

  Similarly, the subsequent rows are read. The drive signal is the same as in the first row. A period T46 to T52 in FIG. 16 corresponds to a period T36 to T42.

  Note that φPDR may always be high after the end of reading (after φS is turned off).

  As can be understood from the above description, since each pixel remains in the PD2 division state while φPDB remains low even in the period T1, the pupil signal on one side of each pixel in the vertical direction or the horizontal direction is displayed. The output and the pupil signal output on the other side in the vertical direction or the horizontal direction can be obtained. Furthermore, it is clear from the above description that an electronic shutter with the same exposure timing for all effective pixels can be used when obtaining such a focus detection signal. Further, it is possible to perform a rolling shutter operation that is reset for each row regardless of the presence or absence of the charge storage units 43 and 44.

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

  When the half-press operation of the release button of the operation unit 9a is performed, the microprocessor 9 in the electronic camera 1 drives the imaging control unit 4 in synchronization with the half-press operation. The imaging control unit 4 sends a control signal to the solid-state imaging device 3 to cause the solid-state imaging device 3 to perform the operation described with reference to FIG. 16 to obtain signals from all the pixels 20V, 20H, and 20N. Are stored in the memory 7 via the signal processing unit 5 and the A / D conversion unit 6.

  Next, the microprocessor 9 determines that the currently set focus adjustment mode is a mode in which focus adjustment is performed only based on, for example, the focus detection area 35 shown in FIGS. 3 and 4 (hereinafter referred to as “focus detection area 35 mode”). .)), The signals from the photodiodes 41 and 42 of all the pixels 20V in the focus detection area 35 in the focus detection signals previously stored in the memory 7 are picked up, and based on these signals. Thus, the focus detection calculation unit 10 is made to calculate the defocus amount by causing the focus detection calculation unit 10 to perform calculation (focus adjustment state detection processing) according to the pupil division phase difference method.

  In addition, when the currently set focus adjustment mode is a mode in which focus adjustment is performed based on, for example, all the focus detection areas 32 to 37 illustrated in FIG. 3 (hereinafter, referred to as “all focus detection area mode”). In addition to calculating the defocus amount with respect to the focus detection region 35 as described above, the defocus amount is similarly calculated with respect to the focus detection regions 32 to 34, 36, and 37.

  Thereafter, when the currently set focus detection mode is the focus detection area 35 mode, the microprocessor 9 performs lens control so that the in-focus state is obtained in accordance with the defocus amount relating to the focus detection area 35 obtained previously. The photographing lens 2 is adjusted by the unit 2a. When the currently set focus detection mode is the all-focus detection area mode, the microprocessor 9 is set to the adjusted focus adjustment state determined based on the defocus amount of each focus detection area previously obtained. Then, the lens control unit 2a adjusts the photographing lens 2. Subsequently, the microprocessor 9 sets shooting conditions (aperture, shutter time, etc.) for the main shooting.

  Next, the microprocessor 9 causes the lens control unit 2a to adjust the photographing lens 2 so that the in-focus state is obtained according to the previously obtained defocus amount. Subsequently, the microprocessor 9 sets shooting conditions (aperture, shutter time, etc.) for the main shooting.

  Next, the microprocessor 9 operates the lens control unit 2a so as to satisfy the set aperture condition, and the shutter time set in step S9 is synchronized with the full pressing operation of the release button of the operation unit 9a. By driving the imaging control unit 4 under conditions, the image signal is read out and actual imaging is performed. At this time, the image signal is read out by the operation shown in FIG. The image signal is accumulated in the memory 7 by the imaging control unit 4.

  Thereafter, the microprocessor 9 performs a desired process in the image processing unit 13 or the image compression unit 12 as necessary based on a command from the operation unit 9a, and outputs a processed signal to the recording unit to the recording medium 11a. Record.

  According to the present embodiment, in the pixels 20V and 20H, the PD2 divided state (the state where the embedded photodiodes 41 and 42 are electrically separated) and the PD combined state (the embedded photodiode) according to the control signal applied to the gate electrode 67. 41 and 42 are electrically connected to each other). Therefore, by setting the PD2 division state at the time of focus detection, it is possible to detect the focus adjustment state of the photographing lens by obtaining a focus detection signal from the pixels 20V and 20H, and at the time of imaging, the pixel is combined. 20V and 20H do not cause a state similar to a pixel defect, and the image quality can be improved.

  In this embodiment, as described above, there is a region having sensitivity to incident light in the region below the gate electrode 67 in the PD merged state at the time of imaging. Therefore, according to the present embodiment, as compared with the case where the floating diffusion is arranged between one part and the other part of the photoelectric conversion unit divided into two as in the solid-state imaging device disclosed in Patent Document 4. The sensitivity at the time of imaging can be improved.

[Second Embodiment]
FIG. 17 is a schematic plan view schematically showing a solid-state image sensor 103 (particularly, its imaging region 31) of an electronic camera as an imaging device according to the second embodiment of the present invention, and corresponds to FIG. . 18 is a schematic enlarged view in which an arbitrary region of the imaging region 31 in FIG. 17 is enlarged, and corresponds to FIG. FIG. 19 is a schematic flowchart showing the operation of the electronic camera according to the present embodiment. 17 and 18, the same or corresponding elements as those in FIGS. 3 and 4 are denoted by the same reference numerals, and redundant description thereof is omitted.

  The difference between the present embodiment and the first embodiment is that no special focus detection areas 32 to 37 are set in the imaging area 31, and all the pixels 20 in the effective area are shown in FIGS. The only difference is the pixel 20V shown in FIG. 11 and the point that the electronic camera according to the present embodiment performs the operation shown in FIG.

  The operation of the electronic camera according to this embodiment will be described with reference to FIGS.

  When the half-press operation of the release button of the operation unit 9a is performed (step S1), the microprocessor 9 in the electronic camera 1 drives the imaging control unit 4 in synchronization with the half-press operation. The imaging control unit 4 reads out imaging signals for subject confirmation from all pixels or predetermined pixels and accumulates them in the memory 7 by a known method predetermined in order to confirm the subject. At this time, when all the pixels are read out, for example, the same operation as that shown in FIG. 15 is performed. Then, the image processing unit 13 recognizes the subject from the signal using an image recognition technique (step S2). For example, in the face recognition mode, a face is recognized as a subject. Then, the image processing unit 13 extracts the center coordinates of the subject (step S3).

  Thereafter, the microprocessor 9 is a pixel row corresponding to an autofocus line sensor to be used for focus detection, which is optimal for accurately detecting the focus adjustment state with respect to the subject according to the center coordinates of the subject extracted in step 3. The coordinates (position) of (column in the Y-axis direction) are set (step S4). Further, the microprocessor 9 sets shooting conditions (aperture, focus adjustment state, shutter time, etc.) for focus detection based on the recognition result in step S2 (step S5).

  Subsequently, the microprocessor 9 operates the lens control unit 2a so as to satisfy the conditions such as the aperture set in step S5, and the coordinates of the pixel row set in step S4 under the conditions such as the shutter time set in step S5. Accordingly, by driving the imaging control unit 4, a signal for autofocus (automatic focus adjustment) is read and stored in the memory 7 (step S 6). At this time, the image signal for autofocus is read out by the same operation as that shown in FIG.

  Next, the microprocessor 9 outputs the signal of each pixel in the pixel row (pixel row in the Y-axis direction) of the coordinates set in step S4 from the signals of all the pixels acquired in step S6 and stored in the memory 7. The focus detection calculation unit 10 calculates the defocus amount by picking up and causing the focus detection calculation unit 10 to perform calculation (focus adjustment state detection processing) according to the pupil division phase difference method based on these signals. (Step S7).

  Next, the microprocessor 9 causes the lens control unit 2a to adjust the photographing lens 2 so that the in-focus state is obtained according to the defocus amount calculated in step S7. Subsequently, the microprocessor 9 sets shooting conditions (aperture, shutter time, etc.) for the main shooting (step S9).

  Next, the microprocessor 9 operates the lens control unit 2a so as to satisfy the conditions such as the aperture set in step S9, and the shutter set in step S9 in synchronization with the full pressing operation of the release button of the operation unit 9a. By driving the imaging control unit 4 under conditions such as time, an image signal is read out and actual imaging is performed (step S10). At this time, the image signal is read out by the same operation as that shown in FIG. The image signal is accumulated in the memory 7 by the imaging control unit 4.

  Thereafter, the microprocessor 9 performs a desired process in the image processing unit 13 or the image compression unit 12 as necessary based on a command from the operation unit 9a, and outputs a processed signal to the recording unit to the recording medium 11a. Record.

  According to the electronic camera 1 according to the present embodiment, advantages similar to those of the first embodiment can be obtained, and the focus detection area can be arbitrarily set according to the subject, so that the autofocus can be performed with high accuracy. It can be performed.

  Note that all the pixels 20 in the effective area may be the pixels 20H illustrated in FIG. 12 instead of the pixels 20V. In this case, in the operation shown in FIG. 19, in step S4, coordinates (positions) of pixel columns (columns in the X-axis direction) corresponding to the autofocus line sensor are set. In step S7, a signal of each pixel in the pixel row (pixel row in the X-axis direction) set in step S4 is picked up, and the defocus amount is calculated in the focus detection calculation unit 10 based on these signals. Let

[Third Embodiment]
FIG. 20 is a schematic plan view schematically showing a solid-state image sensor 203 (particularly, its imaging region 31) of an electronic camera as an imaging device according to the third embodiment of the present invention, and corresponds to FIG. 3 and FIG. doing. FIG. 21 is a schematic enlarged view in which the vicinity of the focus detection region 36 in FIG. 20 is enlarged, and corresponds to FIGS. 4 and 18. 20 and 21, elements that are the same as or correspond to those in FIGS. 3, 4, 17, and 18 are assigned the same reference numerals, and redundant descriptions thereof are omitted.

  This embodiment differs from the first embodiment in that only the pixels 20 in the focus detection regions 32, 36, and 37 extending in the X-axis direction in the imaging region 31 are the pixels 20H shown in FIG. The remaining pixel 20 is the pixel 20V shown in FIGS.

  Also in this embodiment, the same advantages as in the first embodiment can be obtained, and each pixel of the pixel column in the Y-axis direction at a position corresponding to the subject is almost the same as in the second embodiment. Based on the signal, the focus adjustment state can be detected. In the second embodiment, since only the pixel 20V is used, only the phase shift amount in the Y-axis direction due to pupil division can be detected. Therefore, the focus adjustment state cannot always be accurately detected depending on the subject. . On the other hand, since the pixel 20H is used in the focus detection areas 32, 36, and 37, the phase shift amount in the X-axis direction direction is detected although it is limited to the position of the focus detection areas 32, 36, and 37. Is possible. Therefore, according to the present embodiment, it is possible to detect the focus adjustment state with high accuracy for various subjects as compared with the second embodiment.

[Fourth Embodiment]
FIG. 22 is a schematic plan view schematically showing an enlarged part of an imaging region of a solid-state imaging device of an electronic camera as an imaging device according to the fourth embodiment of the present invention. 5, corresponding to FIG. 18 and FIG.

  This embodiment is different from the first embodiment in that the pixel 20V shown in FIGS. 6 to 11 and the pixel 20H shown in FIG. 12 are arranged in a checkered pattern over the entire imaging region 31. And the point that basically the same operation as that shown in FIG. 19 is performed.

  In the present embodiment, in the operation shown in FIG. 19, in step S3, the image processing unit 13 extracts not only the center coordinates of the subject but also the length direction. In step S4, a pixel row corresponding to an autofocus line sensor to be used for focus detection, which is optimal for accurately detecting the focus adjustment state for the subject in accordance with the center coordinates and the longitudinal direction of the subject extracted in step 3 Coordinates (position / longitudinal direction) are set (step S4). However, as for this pixel column, every other pixel column of the pixel 20V is set in the Y-axis direction, and every other pixel column of the pixel 20H is set in the X-axis direction. In step S7, a signal of each pixel in the pixel row having the coordinates set in step S4 is picked up, and based on these signals, the focus detection calculation unit 10 calculates the defocus amount.

  According to the present embodiment, the same advantages as in the first embodiment can be obtained, and not only the position of the focus detection area but also the direction can be arbitrarily set according to the subject, so that higher accuracy can be obtained. Thus, it is possible to detect the focus adjustment state of various subjects.

[Modification]
In each of the above-described embodiments, for example, the pixel shown in FIG. 23 or the pixel shown in FIG. 24 may be used instead of the pixel 20V shown in FIGS.

  FIG. 23 is a schematic cross-sectional view showing a pixel according to the first modification, and corresponds to FIG. FIG. 24 is a schematic cross-sectional view showing a pixel according to the second modification, and corresponds to FIG. 23 and 24, elements that are the same as or correspond to those in FIG. 9 are given the same reference numerals, and redundant descriptions thereof are omitted. The pixel shown in FIG. 23 and the pixel shown in FIG. 24 differ from the pixel 20V shown in FIGS. 6 to 11 only in the cross-sectional structure near the gate electrode 67.

  In the pixel shown in FIG. 23 and the pixel shown in FIG. 24, a trench is formed between the embedded photodiodes 41 and 42 on the main surface side of the silicon substrate, and a gate electrode 67 made of polysilicon or ITO is formed in the trench with a silicon oxide film or the like. The insulating film 90 is formed. Accordingly, in both the pixel shown in FIG. 23 and the pixel shown in FIG. 24, the gate electrode 67 extends into the region between the opposing end faces of the embedded photodiode 41 on one side and the embedded photodiode 42 on the other side. Yes.

  In the pixel shown in FIG. 23, the impurity is located at a position closer to the lower side than the charge storage layer 63 between the N-type charge storage layer 63 of the embedded photodiode 41 and the N-type charge storage layer 63 of the embedded photodiode 42. An N-type diffusion region 91 having a low concentration is formed. On the other hand, such an N type diffusion region 91 is not formed in the pixel shown in FIG.

  In both the pixel shown in FIG. 23 and the pixel shown in FIG. 24, the voltage applied to the gate electrode 67 is changed, so that the embedded photodiodes 41 and 42 are electrically connected to each other. It can be set to an electrically separated state. In any pixel, when the two are electrically connected, the lower region near the gate electrode 67 has a photoelectric conversion function, and when the two are electrically separated, the gate electrode 67 has a photoelectric conversion function. The neighboring lower region does not have a photoelectric conversion function.

  In the pixel shown in FIG. 23 or the pixel shown in FIG. 24, since the gate electrode 67 extends into the region between the opposing end surfaces of the embedded photodiode 41 on one side and the embedded photodiode 42 on the other side, the embedded photodiode It is easy to separate 41 and 42, and the separation gate length can be shortened. For this reason, there is an effect that it can be miniaturized, and it is possible to further reduce the amount of loss of light incident on the gate electrode 67 at the time of imaging, thereby further improving the sensitivity.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this embodiment.

  For example, CMOS image sensors having various pixel structures are known, but the present invention can also be applied to these image sensors. The present invention can also be applied to various image sensors other than the CMOS type image sensor.

  In the above embodiment, the connection / separation transistor 55 formed by the gate electrode 67 is a MOS transistor, but may be a junction field effect transistor, for example.

  Needless to say, each of the conductivity types described above may be a reverse conductivity type. Furthermore, in each of the above-described embodiments, an example of a pixel that can be divided into two by one dividing line has been given. However, in the present invention, a pixel that can be divided into three or more by using a plurality of dividing lines is employed. Also good.

  Each of the above-described embodiments and modifications is an example in which the photoelectric conversion unit connection / separation structure according to the present invention is used in a solid-state imaging device, but the photoelectric conversion unit connection / separation structure according to the present invention is, for example, It can also be used for measuring devices using light.

DESCRIPTION OF SYMBOLS 1 Electronic camera 3 Solid-state image sensor 20,20V, 20H, 20N Pixel 41,42 Embedded photodiode (photoelectric conversion part)
67 Gate electrode CC 'Dividing line

Claims (35)

An image sensor having a plurality of pixels,
At least some of the plurality of pixels are
A first photoelectric conversion unit and a second photoelectric conversion unit for converting light into electric charge;
A first mode in which the first photoelectric conversion unit and the second photoelectric conversion unit are electrically connected to each other, and the first photoelectric conversion unit and the second photoelectric conversion unit are electrically separated, and the first photoelectric conversion unit Mode setting means for setting one of the second mode in which the charge photoelectrically converted in step 2 and the charge photoelectrically converted in the second photoelectric conversion unit are sent out independently of each other;
The region between the first photoelectric conversion unit and the second photoelectric conversion unit has a photoelectric conversion function of converting light into electric charge when the mode setting unit sets the first mode, and the mode An image pickup device having no photoelectric conversion function for converting light into electric charge when set in the second mode by a setting means. The imaging device according to claim 1,
The mode setting means has a gate electrode,
The image pickup device, wherein the gate electrode extends into a region between opposing end surfaces of the first photoelectric conversion unit and the second photoelectric conversion unit. The imaging device according to claim 2,
The imaging device, wherein the gate electrode is provided in a trench formed between the first photoelectric conversion unit and the second photoelectric conversion unit. The imaging device according to claim 1,
The mode setting means has a gate electrode,
The imaging device, wherein the gate electrode does not advance into a region between opposed end surfaces of the first photoelectric conversion unit and the second photoelectric conversion unit. In the image sensor according to any one of claims 2 to 4,
The imaging device, wherein the gate electrode constitutes a gate of a MOS transistor having a semiconductor region of the first photoelectric conversion unit as a source and a semiconductor region of the second photoelectric conversion unit as a drain. In the image sensor according to any one of claims 2 to 5,
The image pickup device, wherein the gate electrode is made of a material having translucency with respect to at least a part of a visible wavelength range. In the image sensor according to any one of claims 2 to 6,
The image pickup device, wherein the gate electrode is made of ITO or polysilicon. In the imaging device according to any one of claims 1 to 7,
An imaging device comprising: a microlens that guides light to the first photoelectric conversion unit and the second photoelectric conversion unit. In the imaging device according to any one of claims 1 to 8,
At least some of the plurality of pixels accumulate the charge photoelectrically converted by the first photoelectric storage unit and the second photoelectric conversion unit that store the charge photoelectrically converted by the first photoelectric conversion unit. A second charge storage unit;
When the second mode is set by the mode setting means, the timing at which the charge photoelectrically converted by the first photoelectric conversion unit is sent from the first photoelectric conversion unit to the first charge storage unit and the second photoelectric conversion unit An image pickup device, wherein the charge photoelectrically converted by the conversion unit is sent out from the second photoelectric conversion unit to the second charge storage unit at the same timing. The imaging device according to claim 9,
At least some of the plurality of pixels further include a floating diffusion portion,
The charge accumulated in the first charge storage unit is transferred to the floating diffusion unit through the first transfer unit,
The image pickup device, wherein the charge accumulated in the second charge storage unit is transferred to the floating diffusion unit via a second transfer unit. A first photoelectric conversion unit that converts light into electric charge;
A second photoelectric conversion unit different from the first photoelectric conversion unit for converting light into electric charge;
A first mode in which the first photoelectric conversion unit and the second photoelectric conversion unit are electrically connected to each other, and the first photoelectric conversion unit and the second photoelectric conversion unit are electrically separated, and the first photoelectric conversion unit Mode setting means for setting any one of the second mode in which the charge photoelectrically converted in step 2 and the charge photoelectrically converted in the second photoelectric conversion unit are sent out independently from each other,
The region between the first photoelectric conversion unit and the second photoelectric conversion unit has a photoelectric conversion function of converting light into electric charge when the mode setting unit sets the first mode, and the mode An image pickup device having no photoelectric conversion function for converting light into electric charge when set in the second mode by a setting means. The imaging device according to claim 11,
The mode setting means has a gate electrode,
The image pickup device, wherein the gate electrode extends into a region between opposing end surfaces of the first photoelectric conversion unit and the second photoelectric conversion unit. The image sensor according to claim 12,
The imaging device, wherein the gate electrode is provided in a trench formed between the first photoelectric conversion unit and the second photoelectric conversion unit. The imaging device according to claim 11,
The mode setting means has a gate electrode,
The imaging device, wherein the gate electrode does not advance into a region between opposed end surfaces of the first photoelectric conversion unit and the second photoelectric conversion unit. The imaging device according to any one of claims 12 to 14,
The imaging device, wherein the gate electrode constitutes a gate of a MOS transistor having a semiconductor region of the first photoelectric conversion unit as a source and a semiconductor region of the second photoelectric conversion unit as a drain. The imaging device according to any one of claims 12 to 15,
The image pickup device, wherein the gate electrode is made of a material having translucency with respect to at least a part of a visible wavelength range. The image sensor according to any one of claims 12 to 16,
The image pickup device, wherein the gate electrode is made of ITO or polysilicon. The imaging device according to any one of claims 11 to 17,
An imaging device comprising: a microlens that guides light to the first photoelectric conversion unit and the second photoelectric conversion unit. The imaging device according to any one of claims 11 to 18,
The pixel further includes a first charge storage unit that accumulates charges photoelectrically converted by the first photoelectric conversion unit, and a second charge storage unit that accumulates charges photoelectrically converted by the second photoelectric conversion unit,
When the second mode is set by the mode setting means, the timing at which the charge photoelectrically converted by the first photoelectric conversion unit is sent from the first photoelectric conversion unit to the first charge storage unit and the second photoelectric conversion unit An image pickup device, wherein the charge photoelectrically converted by the conversion unit is sent out from the second photoelectric conversion unit to the second charge storage unit at the same timing. The image pickup device according to claim 19,
The pixel further includes a floating diffusion part,
The charge accumulated in the first charge storage unit is transferred to the floating diffusion unit through the first transfer unit,
The image pickup device, wherein the charge accumulated in the second charge storage unit is transferred to the floating diffusion unit via a second transfer unit. A first semiconductor region having a first conductivity type;
A second semiconductor region formed in the first semiconductor region and having a second conductivity type different from the first conductivity type for accumulating photoelectrically converted charges;
A third semiconductor region formed in the first semiconductor region and different from the second semiconductor region having the second conductivity type for accumulating photoelectrically converted charges;
The first mode in which the second semiconductor region and the third semiconductor region are electrically connected to the second semiconductor region and the third semiconductor region are electrically separated, and the electric charge accumulated in the second semiconductor region And a mode setting means for setting any one of a second mode in which charges accumulated in the third semiconductor region are sent out independently of each other, and a pixel having
The region between the second semiconductor region and the third semiconductor region has a photoelectric conversion function for converting light into electric charge when set to the first mode by the mode setting unit, and the mode setting unit When the second mode is set, the image pickup device does not have a photoelectric conversion function for converting light into electric charge. The image sensor according to claim 21, wherein
The mode setting means has a gate electrode,
The image pickup device, wherein the gate electrode extends into a region between opposing end surfaces of the second semiconductor region and the third semiconductor region. The image sensor according to claim 22,
The image pickup device, wherein the gate electrode is provided in a trench formed between the second semiconductor region and the third semiconductor region . The image sensor according to claim 21, wherein
The mode setting means has a gate electrode,
The imaging device, wherein the gate electrode does not extend into a region between opposing end surfaces of the second semiconductor region and the third semiconductor region. The image sensor according to any one of claims 22 to 24,
The imaging device, wherein the gate electrode constitutes a gate of a MOS transistor having the second semiconductor region as a source and the third semiconductor region as a drain. In the imaging device according to any one of claims 22 to 25,
The image pickup device, wherein the gate electrode is made of a material having translucency with respect to at least a part of a visible wavelength range. In the imaging device according to any one of claims 22 to 26,
The image pickup device, wherein the gate electrode is made of ITO or polysilicon. In the imaging device according to any one of claims 21 to 27,
An imaging device comprising a microlens for guiding light to the second semiconductor region and the third semiconductor region. In the imaging device according to any one of claims 21 to 28,
The pixel further includes a first charge storage region that temporarily accumulates charges accumulated in the second semiconductor region and a second charge storage region that temporarily accumulates charges accumulated in the third semiconductor region. Prepared,
When the second mode is set by the mode setting means, the charge accumulated in the second semiconductor region is sent out from the second semiconductor region to the first charge storage region and accumulated in the third semiconductor region. The imaging device is characterized in that the timing at which the generated charge is sent out from the third semiconductor region to the second charge storage region is the same timing. The imaging device according to claim 29,
The pixel further comprises a floating diffusion region,
The charge accumulated in the first charge storage region is transferred to the floating diffusion region via the first transfer unit,
The image pickup device, wherein the charge accumulated in the second charge storage region is transferred to the floating diffusion region via a second transfer unit.   An image pickup apparatus comprising the image pickup device according to any one of claims 1 to 30. The image sensor according to any one of claims 1 to 30,
An optical system for forming a subject image on the image sensor;
A detection processing unit that outputs a detection signal indicating a focus adjustment state of the optical system based on a signal corresponding to the electric charge obtained in the second mode;
An adjustment unit that performs focus adjustment of the optical system based on a detection signal from the detection processing unit;
An imaging apparatus comprising: A first photoelectric conversion unit and a second photoelectric conversion unit;
A first mode in which the first photoelectric conversion unit and the second photoelectric conversion unit are electrically connected to each other, and the first photoelectric conversion unit and the second photoelectric conversion unit are electrically separated, and the first photoelectric conversion unit Mode setting means for setting one of the second mode in which the charge photoelectrically converted in step 2 and the charge photoelectrically converted in the second photoelectric conversion unit are sent out independently of each other;
The region between the first photoelectric conversion unit and the second photoelectric conversion unit has a photoelectric conversion function of converting light into electric charge when the mode setting unit sets the first mode, and the mode A connection / separation structure of photoelectric conversion units, which does not have a photoelectric conversion function for converting light into electric charges when set to the second mode by a setting unit. The connection / separation structure of the photoelectric conversion unit according to claim 33,
The mode setting means has a gate electrode,
The coupling / separation structure of photoelectric conversion units, wherein the gate electrode extends into a region between opposed end surfaces of the first photoelectric conversion unit and the second photoelectric conversion unit. In the connection / separation structure of the photoelectric conversion unit according to claim 34,
The gate electrode is provided in a trench formed between the first photoelectric conversion unit and the second photoelectric conversion unit, wherein the photoelectric conversion unit connection / separation structure is provided.

Images