Solid-state imaging device and electronic device

Abstract

In the present invention, an image sensor (102) comprises: a photoelectric conversion unit (10) that generates a photoelectric charge; a sense node (SN) (21) that is connected to the photoelectric conversion unit (10) and that retains a photoelectric charge generated by the photoelectric conversion unit (10); a discharge transistor (15) for discharging, to the outside, the photoelectric charge retained by the sense node (SN) (21); and a voltage control unit (114) that controls the voltage value of OFF voltage applied to the gate of the discharge transistor (15) when the discharge transistor (15) is to be turned OFF.

Description

[Technical field]

[0001] The present disclosure relates to a solid-state imaging device and an electronic device. [Background technology]

[0002] In recent years, solid-state imaging elements such as CMOS (Complementary Metal Oxide Semiconductor) image sensors (CIS: CMOS Image Sensors) have become increasingly widespread and are being used in a variety of fields to replace film-based imaging devices. Solid-state imaging elements are not only being used to replace film-based imaging devices in capturing images of normal visible light, but are also being used prominently in capturing images of invisible light such as ultraviolet light, infrared light, X-rays, and gamma rays.

[0003] Furthermore, among imaging devices having a photoelectric conversion film in a solid-state imaging element, there are imaging devices that handle holes as carriers for photoelectric conversion. For example, photoelectric conversion films that use holes as carriers for photoelectric conversion include quantum (Q: Quantum) dots, InGaAs (iridium gallium arsenide) sensors, and organic compounds. In particular, solid-state imaging devices using InGaAs as a photoelectric conversion film have low dark current and a narrower energy band gap than silicon, and can capture long-wavelength light such as infrared light, so they are expected to be applied to high-sensitivity infrared cameras, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-197368 A [Patent Document 2] Japanese Patent Application Publication No. 11-355664 [Patent Document 3] JP 2019-041226 A [Patent Document 4] JP 2002-330346 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when holes are used as carriers in photoelectric conversion, it is difficult to properly form an overflow path in the pixel circuit, which is a path through which saturated holes escape to a constant voltage source. In that case, there is a problem that excess charge flows into adjacent pixels through the photoelectric conversion film, causing blooming.

[0006] Therefore, the present disclosure provides a solid-state imaging device and electronic equipment that improve the characteristics of a CMOS image sensor. [Means for solving the problem]

[0007] According to the present disclosure, a solid-state imaging device includes a photoelectric conversion unit that generates photocharges, a first charge holding unit connected to the photoelectric conversion unit and holding the photocharges generated by the photoelectric conversion unit, a first transistor for discharging the photocharges held by the first charge holding unit to the outside, and a voltage control unit that controls the voltage value of an off voltage applied to a gate of the first transistor when turning off the first transistor. [Brief description of the drawings]

[0008] [Figure 1] 1 is a block diagram showing a schematic configuration example of an electronic device according to a first embodiment. [Diagram 2] 1 is a block diagram showing a schematic configuration example of an image sensor according to a first embodiment. [Diagram 3] 1 is a circuit diagram of a pixel circuit according to a first embodiment. [Figure 4] 11A and 11B are diagrams illustrating an example of an output voltage and a blooming state according to a gate voltage of a discharge transistor. [Diagram 5] FIG. 1 is a circuit diagram showing an example of a pixel circuit using a photodiode. [Figure 6] FIG. 1 is a circuit diagram of a three-transistor type pixel circuit. [Figure 7] FIG. 11 is a circuit diagram of a pixel circuit and a voltage control circuit according to a second embodiment. [Figure 8] FIG. 13 is a diagram illustrating a connection state of a row control circuit in an image sensor according to a third embodiment. [Figure 9] FIG. 13 is a diagram illustrating a connection state of a row control circuit in an image sensor according to a fourth embodiment. [Figure 10] FIG. 13 is a diagram illustrating a connection state of a row control circuit in an image sensor according to a fifth embodiment. [Figure 11A] FIG. 2 is a diagram illustrating a planar configuration of a light receiving element. [Figure 11B] 11B is a diagram illustrating a cross-sectional configuration taken along line BB' in FIG. 11A. [Figure 12] FIG. 13 is a diagram illustrating a cross-sectional configuration of another light receiving element. [Figure 13] 1 is a block diagram showing an example of a schematic configuration of a vehicle control system; [Figure 14] 4 is an explanatory diagram showing an example of the installation positions of an outside-vehicle information detection unit and an imaging unit; FIG. [Figure 15] 1 is a diagram illustrating an example of a schematic configuration of an endoscopic surgery system. [Figure 16] 2 is a block diagram showing an example of a functional configuration of a camera head and a CCU. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following embodiments, the same components are designated by the same reference numerals, and duplicated descriptions will be omitted.

[0010] 1. First embodiment 2. Second embodiment 3. Third embodiment 4. Fourth embodiment 5. Fifth embodiment 6. Application Examples 7. Mobile Applications 8. Application example to endoscopic surgery system

[0011] 1. First Embodiment Conventional CMOS image sensors are electronic readout sensors, and blooming is prevented by forming an overflow path that discharges electrons accumulated in the photodiode (PD) to a power supply. Some conventional CMOS image sensors also have an overflow gate (OFG) transistor that discharges charges to a constant voltage source. On the other hand, photoelectric conversion films formed using InGaAs sensors use holes as the carriers for photoelectric conversion. The holes and electrons generated from the photoelectric conversion film are recombined, and the amount of electrons lost is handled as a signal. Therefore, in a readout circuit using an N-type MOS transistor (NMOS), it is difficult to accumulate holes, and it is difficult to form an overflow path for holes. Therefore, the voltage of the sense node (SN), which is a diffusion layer connected to the photoelectric conversion film using an InGaAs sensor, rises to the voltage of the top electrode Vtop.

[0012] The reverse bias voltage applied to the photoelectric conversion film decreases as holes recombine with electrons and the SN voltage rises. The reverse bias voltage is the voltage obtained by subtracting the SN voltage from the bias voltage. When the bias voltage becomes nearly 0, the electric field across the PN junction of the photoelectric conversion film decreases, and the current caused by holes flowing from the photoelectric conversion film to the readout circuit decreases. As the current caused by holes flowing to the readout circuit decreases, the current caused by holes diffusing into the N region increases, and the diffused holes are attracted to the electric field across the PN junction of adjacent pixels and flow into the adjacent pixels, causing blooming.

[0013] One way to combat blooming is to form an overflow path to suppress the rise in the SN voltage. To achieve this, it is possible to use a P-type transistor (PMOS) as the MOS transistor that receives the holes output from the photoelectric conversion film. By placing a PMOS, it becomes possible to accumulate holes in the SN, and an overflow path can be formed in the readout circuit. The overflow path for holes in the readout circuit makes it possible to drive the image sensor while maintaining a constant reverse bias, which is expected to suppress blooming in the photoelectric conversion film.

[0014] However, the setting of the barrier against holes formed in the PMOS is in a trade-off relationship between the amount of suppression of blooming occurrence and the amount of saturation signal. In other words, if the barrier is made higher, the amount of saturation signal increases, but the possibility of blooming occurring increases. In contrast, if the barrier is made lower, the amount of suppression of blooming occurrence increases, but the amount of saturation signal decreases. In a pixel array, it is important to suppress blooming in pixels in the effective pixel area adjacent to OPB (Optical Black) pixels, but it is also important to ensure the amount of saturation signal for pixels inside the effective pixel area to improve image quality.

[0015] However, in conventional pixels, the setting of the barrier in the MOS transistor is fixed, so either blooming priority or saturation signal amount priority is selected in advance, making it difficult to meet the demands of each pixel. Therefore, the image sensor according to this embodiment adjusts the ease of forming an overflow path, that is, the barrier height, by changing the gate voltage of the discharge transistor, thereby suppressing the occurrence of blooming and ensuring the saturation charge amount Qs for each pixel.

[0016] [Electronic device configuration] Fig. 1 is a block diagram showing a schematic configuration example of an electronic device according to embodiment 1. As shown in Fig. 1, an electronic device 100 includes, for example, an imaging lens 101, an image sensor 102, a processor 103, and a storage unit 104.

[0017] The imaging lens 101 is an example of an optical system that collects incident light and forms an image on the light receiving surface of the image sensor 102. The light receiving surface may be a surface on which photoelectric conversion elements in the image sensor 102 are arranged. The image sensor 102 performs photoelectric conversion on the incident light to generate image data. The image sensor 102 also performs predetermined signal processing such as noise removal and white balance adjustment on the generated image data.

[0018] The storage unit 104 is configured with, for example, a flash memory, a dynamic random access memory (DRAM), a static random access memory (SRAM), or the like, and records image data input from the image sensor 102, and the like.

[0019] The processor 103 is configured using, for example, a CPU (Central Processing Unit) etc., and may include an application processor that executes an operating system, various application software etc., a GPU (Graphics Processing Unit), a baseband processor etc. The processor 103 executes various processes as necessary on image data input from the image sensor 102, image data read from the storage unit 104 etc., displays the data to the user, transmits the data to the outside via a predetermined network, etc.

[0020] [Image sensor configuration] 2 is a block diagram showing a schematic configuration example of an image sensor according to the first embodiment. The image sensor 102 is a CMOS type image sensor. Here, a CMOS type image sensor is an image sensor created by applying or partially using a CMOS process. For example, the image sensor 102 is configured as a back-illuminated image sensor. This image sensor 102 is an example of a "solid-state imaging device."

[0021] The image sensor 102 according to this embodiment has a stack structure in which, for example, a semiconductor chip on which a pixel array 121 is formed and a semiconductor chip on which peripheral circuits are formed are stacked. The peripheral circuits include, for example, a vertical drive circuit 122, a column processing circuit 123, a horizontal drive circuit 124, and a system control unit 125.

[0022] The image sensor 102 further includes a signal processing unit 126 and a data storage unit 127. The signal processing unit 126 and the data storage unit 127 may be provided on the same semiconductor chip as the peripheral circuits, or may be provided on a different semiconductor chip.

[0023] The pixel array 121 has a configuration in which unit pixels (hereinafter sometimes simply referred to as "pixels") 120, each having a photoelectric conversion element that generates and accumulates an electric charge according to the amount of received light, are arranged in row and column directions, i.e., in a matrix shape, in a two-dimensional lattice. Here, the row direction refers to the arrangement direction of pixels in a pixel row (horizontal direction in the drawing), and the column direction refers to the arrangement direction of pixels in a pixel column (vertical direction in the drawing). A specific circuit configuration and pixel structure of the pixel 120 will be described in detail later.

[0024] In the pixel array 121, a pixel drive line LD is wired in the row direction for each pixel row, and a vertical signal line VSL is wired in the column direction for each pixel column in a matrix-like pixel arrangement. The pixel drive line LD transmits a drive signal for driving the pixels when reading out a signal. Although FIG. 2 shows one pixel drive line LD per pixel, the number is not limited to one. One end of the pixel drive line LD is connected to an output terminal of the vertical drive circuit 122 corresponding to each row.

[0025] The vertical drive circuit 122 is composed of a shift register, an address decoder, etc., and drives each of the pixels 120 of the pixel array 121 simultaneously for all pixels or on a row-by-row basis, etc. In other words, the vertical drive circuit 122, together with a system control unit 125 that controls the vertical drive circuit 122, constitutes a drive unit that controls the operation of each of the pixels 120 of the pixel array 121. Although the specific configuration of this vertical drive circuit 122 is not shown in the figure, it generally has two scan systems: a readout scan system and a sweep-out scan system.

[0026] The readout scanning system sequentially selects and scans the pixels 120 of the pixel array 121 row by row to read out signals from the pixels 120. The signals read out from the pixels 120 are analog signals. The sweep scanning system performs sweep scanning on the readout rows to be read out and scanned by the readout scanning system, prior to the readout scanning by an exposure time.

[0027] The sweep-out scanning by this sweep-out scanning system sweeps out unnecessary charges from the photoelectric conversion elements of the pixels 120 in the readout row, thereby resetting the photoelectric conversion elements. Then, by sweeping out (resetting) the unnecessary charges by this sweep-out scanning system, a so-called electronic shutter operation is performed. Here, the electronic shutter operation refers to the operation of discarding the charges in the photoelectric conversion elements and starting a new exposure (starting the accumulation of charges).

[0028] The signal read by the read operation by the read scanning system corresponds to the amount of light received after the immediately preceding read operation or electronic shutter operation. The period from the read timing of the immediately preceding read operation or the sweep timing of the electronic shutter operation to the read timing of the current read operation is the charge accumulation period (also called the exposure period) in the pixel 120.

[0029] Signals output from each pixel 120 in a pixel row selected and scanned by the vertical drive circuit 122 are input to a column processing circuit 123 through each vertical signal line VSL for each pixel column. The column processing circuit 123 performs predetermined signal processing on signals output from each pixel 120 in the selected row through the vertical signal line VSL for each pixel column of the pixel array 121, and temporarily holds the pixel signals after signal processing.

[0030] Specifically, the column processing circuit 123 performs at least noise removal processing, such as CDS (Correlated Double Sampling) processing and DDS (Double Data Sampling) processing, as signal processing. For example, the CDS processing removes reset noise and pixel-specific fixed pattern noise such as threshold variation of the amplification transistor in the pixel 120. In addition, the column processing circuit 123 has, for example, an AD (analog-digital) conversion function, and converts analog pixel signals read out from the photoelectric conversion elements into digital signals and outputs the digital signals.

[0031] The horizontal driving circuit 124 is composed of a shift register, an address decoder, etc., and sequentially selects readout circuits (hereinafter referred to as pixel circuits) corresponding to pixel columns of the column processing circuit 123. By selective scanning by this horizontal driving circuit 124, pixel signals that have been signal-processed for each pixel circuit in the column processing circuit 123 are sequentially output.

[0032] The system control unit 125 is composed of a timing generator that generates various timing signals, and performs drive control of the vertical drive circuit 122, the column processing circuit 123, and the horizontal drive circuit 124, etc. based on the various timings generated by the timing generator.

[0033] The signal processing unit 126 has at least an arithmetic processing function, and performs various signal processing such as arithmetic processing on the pixel signals output from the column processing circuit 123. The data storage unit 127 temporarily stores data necessary for the signal processing in the signal processing unit 126.

[0034] The image data output from the signal processing unit 126 may be subjected to a predetermined process, for example, in a processor 103 in the electronic device 100 equipped with the image sensor 102, or may be transmitted to the outside via a predetermined network.

[0035] [Configuration of the pixel circuit according to the first embodiment] Fig. 3 is a circuit diagram of a pixel circuit and a voltage control circuit according to the first embodiment. The pixel 120 has the pixel circuit 1 and the voltage control circuit 2 shown in Fig. 3. The pixel 120 having the pixel circuit 1 corresponds to an example of a "solid-state imaging device".

[0036] The pixel circuit 1 has a photoelectric conversion film (also called a photoelectric conversion section) 10, a reset (RST: Reset) transistor 11, an amplifier (AMP: Amplifier) ​​transistor 12, and a selection (SEL: Select) transistor 13. The pixel circuit 1 also has a transfer (TRG: Transfer Gate) transistor 14 and an exhaust (OFG: Overflow Gate) transistor 15. The pixel circuit 1 also has a sense node (SN) 21 which is a diffusion layer of the source of the transfer transistor 14 and the drain of the exhaust transistor 15, and an FD (Floating Diffusion) 20 which is a floating diffusion layer. Furthermore, the pixel circuit 1 according to this embodiment has capacitors 16 and 17. The pixel circuit 1 according to this embodiment is an FD holding type GS (Global shutter) pixel circuit.

[0037] The photoelectric conversion film 10 according to this embodiment is a photoelectric conversion film that uses holes formed by an InGaAs sensor as carriers for photoelectric conversion. The photoelectric conversion film 10 may be formed using, for example, InAsSb (indium arsenide antimony), InAs (indium arsenide), InSb (indium antimony), HgCdTe (mercury cadmium tellurium), Ge (germanium), quantum (Q: quantum) dots, organic compounds, or the like. This photoelectric conversion film 10 is an example of a "photoelectric conversion section."

[0038] The output terminal of the photoelectric conversion film 10 according to this embodiment is connected to the source of the discharge transistor 15, the source of the transfer transistor 14, and the SN21 connected to the capacitor 16. The source of the discharge transistor 15 is connected to the SN21, and the drain is connected to the low voltage source VDR. The source of the transfer transistor 14 is connected to the SN21, and the drain is connected to the FD20. The output terminal of the FD20 is connected to the source of the reset transistor 11, the gate of the amplification transistor 12, and the capacitor 17. The drain of the reset transistor 11 is connected to the low voltage source VDR. In addition, the drain of the amplification transistor 12 is connected to the voltage source VDD. In addition, the source of the amplification transistor 12 is connected to the drain of the selection transistor 13. And the source of the selection transistor 13 is connected to the output signal line. In addition, the capacitor 16 is connected to the output terminal of the photoelectric conversion film 10. In addition, the capacitor 17 is connected to the FD20.

[0039] As described above, the output terminal of the photoelectric conversion film 10 is connected to the SN 21. The photoelectric conversion film 10 outputs holes, which are photoelectric conversion carriers, from the output terminal.

[0040] As described above, the SN21 is connected to the output terminal of the photoelectric conversion film 10, the source of the discharge transistor 15, and the source of the transfer transistor 14. Furthermore, the SN21 has a capacitor 16 which is a high-capacitance element.

[0041] The capacitor 16 has one terminal connected to the SN 21 as described above, and the other terminal connected to the counter electrode. Any voltage such as a constant voltage source (VDD) or a ground potential (GND) can be used as the counter electrode voltage. The capacitor 16 accumulates and holds the charge output from the photoelectric conversion film 10.

[0042] The charge held by SN21 with the capacitor 16 is discharged to the low voltage supply VDR when the drain transistor 15 is turned on. On the other hand, when the transfer transistor 14 is turned on, the charge held by SN21 with the capacitor 16 is transferred to FD20.

[0043] The drain transistor 15 is a PMOS. As described above, the source of the drain transistor 15 is connected to the SN21, and the drain is connected to the low voltage source VDR. Furthermore, the gate of the drain transistor 15 is connected to the drain control signal line.

[0044] The discharge transistor 15, which is a PMOS, turns on when a voltage equal to or lower than the threshold voltage is applied to the gate. Also, the discharge transistor 15 turns off when a voltage higher than the threshold voltage is applied to the gate. That is, the discharge transistor 15 sets a barrier when a voltage higher than the threshold voltage, which is an off voltage, is applied to the gate. When the discharge transistor 15 turns on, it discharges the charges held in the photoelectric conversion film 10 and the capacitor 16 to the low voltage source VDR, and resets the photoelectric conversion film 10.

[0045] Furthermore, as the gate voltage applied to the gate of the discharge transistor 15, two types of voltages are used according to the maximum value of the required saturation charge. One is a gate voltage when the saturation charge is maximized and the barrier is raised to give priority to securing the saturation charge. The gate voltage in this case is called the "saturation charge priority gate voltage". The other is a gate voltage when the saturation charge is reduced and the barrier is lowered to give priority to suppressing the occurrence of blooming. The gate voltage in this case is called the "blooming priority gate voltage". The discharge transistor 15 is a PMOS and holes are accumulated, so the lower the potential of the barrier, the higher the barrier for holes, and the higher the potential of the barrier, the lower the barrier for holes. Therefore, the saturation charge priority gate voltage is higher than the blooming priority gate voltage. For example, in the case of the saturation charge priority gate voltage, the output voltage when the saturation charge is maximum is 360 mV. In addition, in the case of the blooming priority gate voltage, the output voltage when the saturation charge is maximum is 180 mV.

[0046] When the gate voltage is the gate voltage for saturation charge priority, the barrier becomes high in the drain transistor 15, making it difficult to form an overflow path connecting SN21 and the low voltage source VDR, and the saturation charge increases. On the other hand, when the gate voltage is the gate voltage for blooming priority, the barrier becomes low in the drain transistor 15, making it easy to form an overflow path connecting SN21 and the low voltage source VDR, and the saturation charge decreases.

[0047] For each pixel 120, the gate voltage of the discharge transistor 15 is determined according to its position in the pixel array 121. For example, for a pixel 120 adjacent to an OPB pixel, the gate voltage of the discharge transistor 15 is a blooming priority gate voltage. On the other hand, for a pixel 120 located inside the pixel array 121, the gate voltage of the discharge transistor 15 is a saturation charge priority gate voltage.

[0048] The transfer transistor 14 is also a PMOS. As described above, the source of the transfer transistor 14 is connected to the output terminal of the photoelectric conversion film 10, and the drain is connected to the FD 20. Furthermore, the gate of the transfer transistor 14 is connected to a transfer signal line. The transfer transistor 14, which is a PMOS, is turned on when a voltage equal to or lower than a threshold voltage is applied to the gate by a signal sent from the transfer signal line. Furthermore, the transfer transistor 14 is turned off when a voltage higher than the threshold voltage is applied to the gate. When the transfer transistor 14 is turned on, it transfers the charge generated by the photoelectric conversion film 10 and stored in the capacitor 16 to the FD 20.

[0049] As described above, the FD 20 is connected to the drain of the transfer transistor 14, the source of the reset transistor 11, and the gate of the amplification transistor 12. Furthermore, the FD 20 has a capacitor 17 which is a high-capacitance element.

[0050] The capacitor 17 has one terminal connected to the FD 20 as described above, and the other terminal connected to the counter electrode. Any voltage such as a constant voltage source (VDD) or a ground potential (GND) can be used as the counter electrode voltage. The capacitor 17 accumulates and holds the charge transferred from the SN 21.

[0051] When the transfer transistor 14 is turned on, the charge held in the SN 21 equipped with the capacitor 17 is transferred to the FD 20 equipped with the capacitor 17, and the FD 20 accumulates and holds the transferred charge. The FD 20 applies a voltage generated by the charge held in the capacitor 17 and the like to the gate of the amplifying transistor 12. The FD 20 turns on the amplifying transistor 12 by applying a voltage equal to or higher than the threshold voltage to the gate of the amplifying transistor 12. In addition, when the reset transistor 11 is turned on, the charge held in the FD 20 including the capacitor 17 is discharged to the low power supply VDR, and the FD 20 is reset.

[0052] In this embodiment, the pixel circuit 1 is provided with the capacitors 16 and 17 for ensuring the capacitance in the SN 21 and the FD 20, but the capacitors 16 and 17 may not be provided.

[0053] The reset transistor 11 is a PMOS. As described above, the source of the reset transistor 11 is connected to a path leading to the FD20, and the drain is connected to the low voltage source VDR. Furthermore, the gate of the reset transistor 11 is connected to a reset signal line. The reset transistor 11 is turned on when a voltage equal to or lower than the threshold voltage is applied to the gate. Moreover, the reset transistor 11 is turned off when a voltage higher than the threshold voltage is applied to the gate. When the reset transistor 11 is turned on, it discharges the charge accumulated in the FD20 to the low voltage source VDR, thereby resetting the FD20 including the capacitor 17.

[0054] The amplification transistor 12 is an NMOS. As described above, the gate of the amplification transistor 12 is connected to a path leading to the FD20, the source is connected to a voltage source VDD, and the drain is connected to the source of the selection transistor 13. The amplification transistor 12 is turned on when a voltage equal to or greater than the threshold voltage is applied to the gate by the charge output from the FD20. The amplification transistor 12 is turned off when a voltage smaller than the threshold voltage is applied to the gate. When the amplification transistor 12 is turned on, it outputs a current input from the voltage source VDD to the selection transistor 13. That is, the amplification transistor 12 outputs a signal based on the charge held in the FD20 to the selection transistor 13.

[0055] The selection transistor 13 is an NMOS. As described above, the source of the selection transistor 13 is connected to the drain of the amplification transistor 12, and the drain is connected to the output signal line. The gate of the selection transistor 13 is connected to the selection signal line. Since the selection transistor 13 is an NMOS, it turns on when a voltage equal to or greater than the threshold voltage is applied to the gate. It turns off when a voltage smaller than the threshold voltage is applied to the gate. When the selection transistor 13 turns on, it outputs the signal output by the amplification transistor 12 to the output signal line as a pixel signal. That is, the selection transistor 13 controls the selection of pixels during readout by determining whether or not to output a pixel signal from the pixel circuit 1.

[0056] Next, the voltage control circuit 2 will be described. The voltage control circuit 2 is a circuit that adjusts the gate voltage of the discharge transistor 15. The voltage control circuit 2 has a bias voltage source 111, a power source 112, a feedback control unit 113, a voltage control unit 114, and a row control circuit 150. The row control circuit 150 has a plurality of buffers 115 each corresponding to each row of the pixel array 121. Here, in FIG. 3, the pixel circuit 1 is illustrated for one buffer 115, but in reality, the row control circuit 150 collectively controls the pixels 120 included in one row of the pixel array 121 with one buffer 115.

[0057] The bias voltage source 111 is a constant voltage source that outputs a bias voltage having a predetermined voltage. The bias voltage source 111 supplies the predetermined voltage to the power source 112.

[0058] The power supply 112 is, for example, a linear regulator, a charge pump, or a switching regulator. The power supply 112 receives a bias voltage input from a bias voltage source 111. The power supply 112 also receives a feedback signal input from a feedback control unit 113. The power supply 112 then adjusts and outputs a voltage in response to the feedback signal. For example, when the feedback signal is a signal that represents a difference from a reference voltage, the power supply 112 adjusts the voltage so as to reduce the difference.

[0059] The feedback control unit 113 receives an input of the output voltage of the power supply 112. The feedback control unit 113 also receives an input of information on a designated gate voltage from the voltage control unit 114, either the saturation charge amount priority gate voltage or the blooming priority gate voltage. Then, the feedback control unit 113 compares the output voltage of the power supply 112 with the designated gate voltage to generate a feedback signal. For example, the feedback control unit 113 calculates the difference between the output voltage of the power supply 112 and the designated gate voltage to generate the feedback signal. Then, the feedback control unit 113 outputs the generated feedback signal to the power supply 112.

[0060] The voltage control unit 114 receives setting information of the gate voltage, which of the saturation charge priority gate voltage or the blooming priority gate voltage is used as the gate voltage for each row in the pixel array 121. After that, the voltage control unit 114 holds the setting information of the gate voltage for each row in a register that the voltage control unit 114 owns. Then, the voltage control unit 114 outputs the information of the gate voltage specified by the setting information for each row to the feedback control unit 113. Here, the voltage control unit 114 may notify the feedback control unit 113 of the gate voltage value itself, or may notify the feedback control unit 113 of information representing the value of each gate voltage. The information representing the gate voltage value is information that is set in advance, for example, "0" represents the saturation charge priority gate voltage, and "1" represents the blooming priority gate voltage.

[0061] The voltage control unit 114 also includes a timing generator and outputs a timing pulse for turning on and off the drain transistor 15 to the buffer 115.

[0062] The buffer 115 holds the voltage input from the power supply 112. Then, the buffer 115 applies the held voltage to the gate of the discharge transistor 15 in synchronization with a timing pulse input from the voltage control unit 114.

[0063] [Operation of the pixel circuit according to the first embodiment] Here, the flow of pixel signal generation in the pixel circuit 1 of Fig. 3 will be described. First, the discharge transistor 15 is made conductive to reset the photoelectric conversion film 10, SN21, and capacitor 16. Thereafter, the discharge transistor 15 is turned off, so that the charge generated in the photoelectric conversion film 10 is accumulated and held in the SN21 and capacitor 16. This operation from resetting the photoelectric conversion film 10 to holding the charge in the capacitor 16 is performed simultaneously in all pixels 120 arranged in the pixel array 121. This realizes a global shutter. The period from resetting the photoelectric conversion film 10 to holding the charge in the capacitor 16 corresponds to the exposure period.

[0064] Next, the reset transistor 11 is made conductive to reset the capacitor 17 and the FD 20. Next, the reset transistor 11 is turned off and the transfer transistor 14 is turned on. As a result, the charges stored in the SN 21 and the capacitor 16 are transferred to the FD 20 and are stored and held in the capacitor 17 and the FD 20.

[0065] Then, when the transfer transistor 14 is turned on and holes are accumulated in the FD 20, if the potential of the FD 20 exceeds the potential of the barrier generated by the drain transistor 15, an overflow path is formed via the drain transistor 15. This causes the potential of the SN21 to rise, preventing overflow between the FDs 20 due to saturation of the FDs 20.

[0066] Here, when the gate voltage of the drain transistor 15 is the blooming priority gate voltage, the potential of the barrier generated by the drain transistor 15 is set lower than that of the saturated charge priority gate voltage, and the barrier becomes lower. Therefore, an overflow path via the drain transistor 15 is formed more easily than in the case of the saturated charge priority gate voltage. This makes it possible to suppress the occurrence of blooming more effectively than in the case of the saturated charge priority gate voltage. On the other hand, since the barrier generated by the drain transistor 15 is low, the saturated charge becomes smaller than in the case of the saturated charge priority gate voltage.

[0067] On the other hand, when the gate voltage of the drain transistor 15 is the saturated charge priority gate voltage, the potential of the barrier generated by the drain transistor 15 is set higher than that of the blooming priority gate voltage, and the barrier becomes higher. Therefore, the saturated charge becomes larger than that of the blooming priority gate voltage. On the other hand, since the barrier generated by the drain transistor 15 is high, it is more difficult to form an overflow path via the drain transistor 15 than that of the saturated charge priority gate voltage. Therefore, the occurrence of blooming may increase compared to that of the blooming priority gate voltage.

[0068] Furthermore, when the potential of the accumulated holes while the transfer transistor 14 is off exceeds the potential of the barrier generated by the transfer transistor 14, an overflow path is formed via the transfer transistor 14. Then, the amount of holes that falls below the potential of the barrier generated by the transfer transistor 14 is discharged via the overflow path.

[0069] Furthermore, when the potential of the holes accumulated while the reset transistor 11 is off exceeds the potential of the barrier generated by the reset transistor 11, an overflow path is formed via the reset transistor 11. Then, the number of holes that exceeds the potential of the barrier generated by the reset transistor 11 is discharged via the overflow path.

[0070] The amplification transistor 12 generates a pixel signal according to the charge held in the FD 20. Next, the selection transistor 13 is rendered conductive, so that the pixel signal generated by the amplification transistor 12 is output to an output signal line. This operation from resetting the FD 20 to outputting the pixel signal is performed sequentially for each pixel circuit 1 arranged in the pixel array 121. The pixel signal output processing is performed in all pixel circuits 1 of the pixel array 121, so that a frame, which is the pixel signals for one screen, is generated.

[0071] FIG. 4 is a diagram showing an example of the output voltage and blooming state according to the gate voltage of the discharge transistor. Graph 201 is a graph showing the output voltage and accumulation time in each pixel 120 when the High voltage of the gate voltage is set to the first voltage, which is the highest among the three states. Graph 202 is a graph showing the output voltage and accumulation time in each pixel 120 when the High voltage of the gate voltage is set to the second voltage, which is lower than that in the graph 201. Graph 203 is a graph showing the output voltage and accumulation time in each pixel 120 when the High voltage of the gate voltage is set to the third voltage, which is lower than that in the graph 202. In each of the graphs 201 to 203, the vertical axis shows the output voltage, and the horizontal axis shows the accumulation time of the charge. In the graphs 201 to 203, a curve 221 shows the output voltage of the pixel 120 inside the aperture pixel in the effective pixel area. In addition, a curve 222 shows the output voltage of the pixel 120 at the end of the aperture pixel in the effective pixel area. Moreover, a curve 223 represents the output voltage of the pixel 120 in the first row from the aperture pixel of the OPB pixel. Moreover, a curve 223 represents the output voltage of the pixel 120 in the second row from the aperture pixel of the OPB pixel.

[0072] Moreover, image 211 represents the state of blooming occurring in the case of graph 201, image 212 represents the state of blooming occurring in the case of graph 202, and image 213 represents the state of blooming occurring in the case of graph 203. The portions indicated by dashed lines in images 211 to 213 correspond to the ends of the aperture pixels.

[0073] When the gate voltage is the first voltage, as shown in graph 201, the output voltage of each pixel 120 is higher than in other cases. That is, when the gate voltage is the first voltage, it is found that the amount of saturated charge is larger than in other cases. However, as shown in image 211, blooming occurs significantly in the region from the end of the aperture pixel to the OPB pixel. In contrast, when the gate voltage is set to the second voltage V, as shown in graph 202, the output voltage of each pixel 120 decreases compared to when the gate voltage is the first voltage. However, as shown in image 212, the occurrence of blooming decreases compared to when the gate voltage is the first voltage. Furthermore, when the gate voltage is set to the third voltage, as shown in graph 203, the output voltage of each pixel 120 further decreases compared to when the gate voltage is the second voltage. However, as shown in image 213, the occurrence of blooming further decreases compared to when the gate voltage is the second voltage, and it can be said that blooming is almost suppressed.

[0074] In this way, by lowering the gate voltage of the discharge transistor 15, the amount of saturation charge is reduced, and the image quality is accordingly degraded, but the occurrence of blooming can be suppressed. Therefore, it is preferable to set the gate voltage high inside the aperture pixel and low at the edge of the aperture pixel.

[0075] [Actions and Effects] As described above, the pixel circuit 1 according to this embodiment is an FD retention type, and has a photoelectric conversion film 10 that uses holes as photoelectric conversion carriers. In addition, the pixel circuit 1 according to this embodiment uses a PMOS as the discharge transistor 15, and uses either a saturation charge amount priority gate voltage or a blooming priority gate voltage as the gate voltage of the discharge transistor 15.

[0076] As a result, the pixel circuit 1 according to this embodiment can store holes in the discharge transistor 15, and can form an overflow path to discharge the holes before they flow out to the adjacent pixel 120. Furthermore, by switching the gate voltage of the discharge transistor 15, it is possible to adjust the ease of forming an overflow path and the amount of saturation charge. In other words, it is possible to suppress the occurrence of blooming and increase the amount of saturation charge. Therefore, it is possible to adjust the suppression of blooming and the amount of saturation charge according to the requirements for each pixel 120, and it is possible to improve image quality.

[0077] In addition, in this embodiment, two types of gate voltages are used, but three or more types of gate voltages may be used. In that case, the occurrence of blooming and the amount of saturation charge can be finely adjusted for each pixel.

[0078] [Modification (1) of the first embodiment] In the pixel circuit 1 according to the first embodiment, the gate voltage is switched in accordance with a predetermined gate voltage setting, but in the pixel circuit 1 according to this modification, the gate voltage is controlled from the subsequent image processing.

[0079] The voltage control unit 114 captures an image of the entire area of ​​the pixel array 121. Then, the voltage control unit 114 identifies a pixel in which blooming has occurred and performs image processing. Then, when blooming has occurred, if the current gate voltage of the pixel 120 in which blooming has occurred is a saturation charge priority gate voltage, the voltage control unit 114 determines to change the gate voltage of the discharge transistor 15 of that pixel to a blooming priority gate voltage. Then, the voltage control unit 114 outputs the gate voltage of the pixel 120 in which blooming has occurred to the feedback control unit 113 as a blooming priority gate voltage.

[0080] With this configuration, it is possible to suppress the occurrence of blooming in the pixel 120 where the blooming occurs, and it is possible to reduce the occurrence of blooming while maintaining image quality.

[0081] Furthermore, in this embodiment, the voltage control unit 114 determines the pixel 120 in which blooming has occurred, but this determination process may be executed by an external computer.

[0082] [Modification (2) of the first embodiment] In the pixel circuit 1 according to the first embodiment, the gate voltage is switched in accordance with a predetermined gate voltage setting, but the pixel circuit 1 according to this modification controls the gate voltage in accordance with the analog gain.

[0083] The image sensor 102 can adjust the analog gain. For example, it is possible to set whether to perform 10-bit AD (Analog / Digital) conversion at 100 mV, or to perform 10-bit AD conversion at 50 mV with the analog gain increased.

[0084] The voltage control unit 114 receives the specified gain as input. Then, the voltage control unit 114 adjusts the gate voltage of the discharge transistor 15 so that the amount of saturated charge decreases in response to an increase in the gain. For example, when the analog gain is doubled, the voltage control unit 114 sets the gate voltage of the discharge transistor 15 so that the amount of saturated charge becomes 1 / 2.

[0085] With this configuration, it is possible to suppress blooming and to inhibit the generation of unnecessary electric charges.

[0086] [Modification (3) of the first embodiment] In the above description, the gate voltage of the discharge transistor 15 is variable, but the gate voltage of the transfer transistor 14 may be variable together with the gate voltage of the reset transistor 11. By adopting such a configuration, it is also possible to form an overflow path in the transfer transistor 14 to discharge holes accumulated in SN21.

[0087] [Modification (4) of the first embodiment] In the above explanation, the pixel circuit 1 having the photoelectric conversion film 10 using an InGaAs sensor has been described, but it is also possible to apply it to a pixel circuit 1 having a photodiode 18 arranged on a silicon semiconductor substrate as shown in FIG. 5. FIG. 5 is a circuit diagram showing an example of a pixel circuit using a photodiode. The pixel circuit 1 in FIG. 5 has a photodiode 18 arranged on a silicon substrate. Electrons generated in the photodiode 18 are accumulated and held in the emission transistor 15. The photodiode 18 in this case is an example of a "photoelectric conversion unit."

[0088] In this case, the drain transistor 15 is an NMOS. If the drain transistor 15 is an NMOS, lowering the potential of the barrier makes the barrier higher, making it difficult for an overflow path to be formed, and increasing the amount of saturated charge. Conversely, raising the potential of the barrier makes the barrier lower, making it easier to form an overflow path, and further suppressing the occurrence of blooming, but reducing the amount of saturated charge. The drain transistor 15 has a barrier set when a voltage lower than the threshold voltage, which is the off voltage, is applied to the gate.

[0089] [Modification (5) of the first embodiment] In the above description, the pixel circuit 1 having a global shutter function has been described, but the present invention is also applicable to a pixel circuit 1 having a rolling shutter function. Fig. 6 is a circuit diagram of a three-transistor type pixel circuit. For example, when using the pixel circuit 1 consisting of three transistors shown in Fig. 6, it is possible to suppress the occurrence of blooming and adjust the amount of saturation charge by changing the gate voltage of the reset transistor 11.

[0090] 2. Second embodiment 7 is a circuit diagram of a pixel circuit and a voltage control circuit according to the second embodiment. The image sensor 102 according to the embodiment differs from the first embodiment in that the power supply is adjusted by an external power supply. In the following description, the same operations as those of the components in the first embodiment will not be described.

[0091] The external power supply 116 is connected to the buffer 115 of the image sensor 102 according to this embodiment. The voltage to be output is set in the external power supply 116 using information on the setting of the gate voltage according to the desired saturation charge amount. The external power supply 116 outputs the set voltage. Here, in FIG. 7, a state in which the external power supply 116 outputs one type of voltage to the row control circuit 150 is described, but in reality, the external power supply 116 outputs multiple types of voltages to the row control circuit so that different types of voltages can be selected for each row. For example, the external power supply 116 outputs a saturation charge amount priority gate voltage or a blooming priority gate voltage that can be selected by each row.

[0092] The buffer 115 receives and accumulates a voltage input from an external power supply 116. Then, the buffer 115 applies a gate voltage to the gate of the drain transistor 15 in accordance with an on-off pulse signal input from the voltage control unit 114.

[0093] As described above, the image sensor 102 according to this embodiment receives an input of a voltage corresponding to the amount of saturation charge from the external power supply 116, and applies the voltage as a gate voltage to the discharge transistor 15. In this way, even if the external power supply 116 is used, the gate voltage applied to the discharge transistor 15 can be adjusted, and the occurrence of blooming can be suppressed and the amount of bar-sum charge can be adjusted to improve image quality.

[0094] Even in a configuration in which a voltage is input from the external power supply 116, it is possible to adjust the gate voltage according to post-stage image processing, as in the modified example (1) of the first embodiment. In this case, it is preferable to notify the external power supply 116 of information obtained from the post-stage image processing. For example, a configuration may be adopted in which the voltage control unit 114 determines which pixels 120 will experience blooming due to image processing, and notifies the external power supply 116 of the determination result.

[0095] 3. Third embodiment 8 is a diagram showing a connection state of a row control circuit in an image sensor according to the third embodiment. The image sensor 102 according to this embodiment uses the same gate voltage for the discharge transistors 15 of all pixel circuits 1 included in the pixel array 121.

[0096] The power supply 112 has one wiring capable of outputting a variable potential to the row control circuit 150. The power supply 112 outputs a specified gate voltage to the row control circuit 150 under the control of the voltage control unit 114. For example, a case where a saturation charge amount priority gate voltage and a blooming priority gate voltage are used will be described. When it is desired to suppress blooming in the entire pixel array 121, the power supply 112 outputs the blooming priority gate voltage. On the other hand, when it is desired to increase the saturation charge amount in the entire pixel array 121, the power supply 112 outputs the saturation charge amount priority gate voltage.

[0097] The row control circuit 150 has a buffer 115 for each row of the pixel array 121. Each buffer 115 is connected to the gate of the discharge transistor 15 of the pixel circuit 1 of each row of the pixel array 121.

[0098] The row control circuit 150 receives the gate voltage and stores it in each buffer 115. Then, the row control circuit 150 applies the gate voltage stored in the buffer 115 in response to the on / off of each discharge transistor 15. As a result, the same gate voltage is applied to the discharge transistors 15 of the pixel circuits 1 in all rows.

[0099] As described above, in the image sensor 102 according to this embodiment, the same gate voltage is applied to the discharge transistors 15 of the pixel circuits 1 of all rows of the pixel array 121. As a result, when it is desired to suppress blooming in the pixel array 121, a gate voltage of a voltage that suppresses blooming is used in the discharge transistors 15 in the pixel circuits 1 of all pixels 120 in the pixel array 121. Also, when it is desired to improve image quality by increasing the saturation charge amount of the pixel array 121, a gate voltage of a voltage that increases the saturation charge amount is used in the discharge transistors 15 in the pixel circuits 1 of all pixels 120 in the pixel array 121. As a result, it is possible to adjust the suppression of blooming occurrence and the saturation charge amount for each pixel array 121.

[0100] 4. Fourth Embodiment 9 is a diagram showing a connection state of a row control circuit in an image sensor according to the fourth embodiment. The image sensor 102 according to this embodiment applies a different gate voltage to each row included in a pixel array 121.

[0101] The power supply 112 has wiring capable of outputting variable potentials to the row control circuit 150, the number of which corresponds to the number of types of gate voltages. The power supply 112 outputs various gate voltages to each wiring. For example, when three types of voltages are used as the gate voltages, the power supply 112 has three wirings extending to the row control circuit 150. The power supply 112 outputs three different types of gate voltages to each wiring.

[0102] The row control circuit 150 has a buffer 115 for each row of the pixel array 121. Each buffer 115 is connected to the gate of the discharge transistor 15 of the pixel circuit 1 of each row of the pixel array 121. Furthermore, each buffer 115 is connected to a switch capable of selecting one of the wirings extending from the power supply 112.

[0103] The row control circuit 150 receives setting information of the gate voltage to be applied to each row from the voltage control unit 114. Then, the row control circuit 150 connects a buffer 115 corresponding to each row to a wiring to which the type of gate voltage to be applied to each row is input, according to the setting information of the gate voltage of each row.

[0104] The row control circuit 150 receives different types of gate voltages for each wiring and causes each buffer 115 connected to each wiring to hold the voltage input to that wiring. Then, the row control circuit 150 applies the gate voltages held in the buffers 115 to the discharge transistors 15 of the pixel circuits 1 of each row in response to the on / off state of each discharge transistor 15. This causes a different gate voltage to be applied to the discharge transistors 15 for each row.

[0105] As described above, in the image sensor 102 according to this embodiment, a different gate voltage is applied to the discharge transistor 15 of the pixel circuit 1 for each row of the pixel array 121. This makes it possible to suppress the occurrence of blooming and adjust the amount of saturation charge for each row of the pixel array 121. For example, a gate voltage that suppresses blooming can be applied to the discharge transistor 15 for a row having pixels 120 for which it is desired to suppress blooming, and a gate voltage that increases the amount of saturation charge can be applied to the discharge transistor 15 for a row having pixels 120 for which it is desired to increase the amount of saturation charge. This allows the image sensor 102 to generate a more appropriate image.

[0106] 5. Fifth Embodiment 10 is a diagram showing a connection state of a row control circuit in an image sensor according to the fifth embodiment. The image sensor 102 according to this embodiment applies different gate voltages to each region of a pixel array 121.

[0107] The pixels 120 of the pixel array 121 according to this embodiment are divided into regions in a lattice shape, for example. The gates of the emission transistors 15 of the pixel circuits 1 of the pixels 120 are connected to one wiring.

[0108] The power supply 112 has wiring capable of outputting variable potentials to the row control circuit 150, the number of which corresponds to the number of types of gate voltages. The power supply 112 outputs various gate voltages to each wiring. For example, when three types of voltages are used as the gate voltages, the power supply 112 has three wirings extending to the row control circuit 150. The power supply 112 outputs three different types of gate voltages to each wiring.

[0109] The row control circuit 150 has a buffer 115 for each row of the pixel array 121. Each buffer 115 is connected to a wiring extending from the gate of the discharge transistor 15 of the pixel circuit 1 in each region of the pixel array 121. Furthermore, each buffer 115 is connected to a switch capable of selecting one of the wirings extending from the power supply 112.

[0110] The row control circuit 150 receives setting information of the gate voltage to be applied to each region from the voltage control unit 114. Then, the row control circuit 150 connects a buffer 115 corresponding to each row to a wiring to which the type of gate voltage to be applied to each region is input, according to the setting information of the gate voltage of each region.

[0111] The row control circuit 150 receives different types of gate voltages for each wiring and causes each buffer 115 connected to each wiring to hold the voltage input to that wiring. Then, the row control circuit 150 applies the gate voltages held in the buffers 115 to the discharge transistors 15 of the pixel circuits 1 in each region in response to the on / off state of each discharge transistor 15. This causes a different gate voltage to be applied to the discharge transistors 15 in each region.

[0112] As described above, in the image sensor 102 according to the present embodiment, different gate voltages are applied to the discharge transistor 15 of the pixel circuit 1 for each region of the pixel array 121. This allows the suppression of blooming and the amount of saturation charge to be adjusted for each region of the pixel array 121. For example, a gate voltage that suppresses blooming can be applied to the discharge transistor 15 in a region having a pixel 120 for which blooming is desired to be suppressed, and a gate voltage that increases the amount of saturation charge can be applied to the discharge transistor 15 in a region having a pixel 120 for which the amount of saturation charge is desired to be increased. This allows the suppression of blooming and the amount of saturation charge to be adjusted for each region of the pixel array 121, and a more appropriate image can be generated. Furthermore, by dividing the region finely, the suppression of blooming and the amount of saturation charge in each pixel can be finely adjusted, and a more appropriate image can be generated.

[0113] (6. Application Examples) Here, a configuration example to which the pixel circuit 1 described in each of the above embodiments can be applied will be described. Fig. 11A is a diagram showing a planar configuration of a light receiving element. Fig. 11B is a diagram showing a cross-sectional configuration along line B-B' in Fig. 11A. For example, each pixel circuit 1 described in each of the embodiments and their modified examples can be applied to the light receiving element shown in Figs. 11A and 11B.

[0114] The light receiving element 501 is applied to an infrared sensor using a compound semiconductor material such as a III-V group semiconductor, and has a photoelectric conversion function for light having a wavelength in the visible region (e.g., 380 nm or more and less than 780 nm) to the short infrared region (e.g., 780 nm or more and less than 2400 nm). The light receiving element 501 is provided with a plurality of light receiving unit regions P (pixels P) arranged, for example, two-dimensionally (FIG. 11B).

[0115] The light receiving element 501 is applied to an infrared sensor using a compound semiconductor material such as a III-V group semiconductor, and has a photoelectric conversion function for light having a wavelength in the visible region (e.g., 380 nm or more and less than 780 nm) to the short infrared region (e.g., 780 nm or more and less than 2400 nm). The light receiving element 501 is provided with a plurality of light receiving unit regions P (pixels P) arranged, for example, two-dimensionally.

[0116] The light receiving element 501 has a central element region R1 and a peripheral region R2 that is provided outside the element region R1 and surrounds the element region R1 (FIG. 11A). The light receiving element 501 has a conductive film 515B that is provided from the element region R1 to the peripheral region R2. The conductive film 515B has an opening in a region that faces the center of the element region R1.

[0117] The light receiving element 501 has a laminated structure of an element substrate 510 and a readout circuit substrate 520. One surface of the element substrate 510 is a light incident surface (light incident surface S1), and the surface opposite to the light incident surface S1 (the other surface) is a bonding surface (bonding surface S2) with the readout circuit substrate 520.

[0118] The element substrate 510 has, in this order from the position closest to the readout circuit substrate 520, a wiring layer 510W, a first electrode 511, a semiconductor layer 510S (first semiconductor layer), a second electrode 515, and a passivation film 516. A surface of the semiconductor layer 510S facing the wiring layer 510W and an end face (side face) are covered with an insulating film 517. The readout circuit substrate 520 is a so-called ROIC (Readout Integrated Circuit), and has a wiring layer 520W and a multi-layered wiring layer 522C in contact with the bonding surface S2 of the element substrate 510, and a semiconductor substrate 521 facing the element substrate 510 with the wiring layer 520W and the multi-layered wiring layer 522C in between.

[0119] The element substrate 510 has a semiconductor layer 510S in the element region R1. In other words, the region where the semiconductor layer 510S is provided is the element region R1 of the light receiving element 501. In the element region R1, a region exposed from the conductive film 515B (a region facing the opening of the conductive film 515B) is the light receiving region. In the element region R1, a region covered with the conductive film 515B is an OPB (Optical Black) region R1B. The OPB region R1B is provided so as to surround the light receiving region. The OPB region R1B is used to obtain a black level pixel signal. The element substrate 510 has an insulating film 517 and a buried layer 518 in the peripheral region R2. The peripheral region R2 is provided with holes H1 and H2 that penetrate the element substrate 510 and reach the readout circuit board 520. In the light receiving element 501, light is incident from the light incident surface S1 of the element substrate 510 through the passivation film 516, the second electrode 515, and the second contact layer 514 onto the semiconductor layer 510S. The signal charge photoelectrically converted in the semiconductor layer 510S moves via the first electrode 511 and the wiring layer 510W, and is read out by the readout circuit board 520. The configuration of each part will be described below.

[0120] The wiring layer 510W is provided across the element region R1 and the peripheral region R2, and has a bonding surface S2 with the readout circuit board 520. In the light receiving element 501, the bonding surface S2 of the element board 510 is provided in the element region R1 and the peripheral region R2, and for example, the bonding surface S2 of the element region R1 and the bonding surface S2 of the peripheral region R2 form the same plane. As described later, in the light receiving element 501, the bonding surface S2 of the peripheral region R2 is formed by providing an embedding layer 518.

[0121] The wiring layer 510W has a contact electrode 519E and a dummy electrode 519ED in, for example, interlayer insulating films 519A and 519B. For example, the interlayer insulating film 519B is disposed on the readout circuit board 520 side, and the interlayer insulating film 519A is disposed on the first contact layer 512 side, and these interlayer insulating films 519A and 519B are laminated. The interlayer insulating films 519A and 519B are made of, for example, an inorganic insulating material. Examples of the inorganic insulating material include silicon nitride (SiN), aluminum oxide (Al2 O 3 ), silicon oxide (SiO 2 ) and hafnium oxide (HfO 2 The interlayer insulating films 519A and 519B may be made of the same inorganic insulating material.

[0122] The contact electrode 519E is provided in, for example, the element region R1. The contact electrode 519E is for electrically connecting the first electrode 511 and the readout circuit board 520, and is provided for each pixel P in the element region R1. The adjacent contact electrodes 519E are electrically separated by the buried layer 518 and the interlayer insulating films 519A and 519B. The contact electrode 519E is formed of, for example, a copper (Cu) pad, and is exposed at the bonding surface S2. The dummy electrode 519ED is provided in, for example, the peripheral region R2. The dummy electrode 519ED is connected to a dummy electrode 522ED of a wiring layer 520W described later. By providing the dummy electrode 519ED and the dummy electrode 522ED, it is possible to improve the strength of the peripheral region R2. The dummy electrode 519ED is formed in, for example, the same process as the contact electrode 519E. The dummy electrode 519ED is made of, for example, a copper (Cu) pad, and is exposed to the bonding surface S2.

[0123] The first electrode 511 provided between the contact electrode 519E and the semiconductor layer 510S is an electrode (anode) to which a voltage for reading out a signal charge (hole or electron, hereinafter, for convenience, the signal charge is described as a hole) generated in the photoelectric conversion layer 513 is supplied, and is provided for each pixel P in the element region R1. The first electrode 511 is provided so as to fill an opening of the insulating film 517, and is in contact with the semiconductor layer 510S (more specifically, a diffusion region 512A described later). For example, the first electrode 511 is larger than the opening of the insulating film 517, and a part of the first electrode 511 is provided in the buried layer 518. That is, the upper surface of the first electrode 511 (the surface on the semiconductor layer 510S side) is in contact with the diffusion region 512A, and a part of the lower surface and side surface of the first electrode 511 is in contact with the buried layer 518. Adjacent first electrodes 511 are electrically isolated by an insulating film 517 and a buried layer 518 .

[0124] The first electrode 511 is made of, for example, any one of titanium (Ti), tungsten (W), titanium nitride (TiN), platinum (Pt), gold (Au), germanium (Ge), palladium (Pd), zinc (Zn), nickel (Ni), and aluminum (Al), or an alloy containing at least one of them. The first electrode 511 may be a single film of such a constituent material, or may be a laminated film combining two or more types. For example, the first electrode 511 is made of a laminated film of titanium and tungsten. The thickness of the first electrode 511 is, for example, several tens of nm to several hundreds of nm.

[0125] The semiconductor layer 510S includes, for example, from a position close to the wiring layer 510W, a first contact layer 512, a photoelectric conversion layer 513, and a second contact layer 514. The first contact layer 512, the photoelectric conversion layer 513, and the second contact layer 514 have the same planar shape, and the end faces of each are disposed at the same position in a planar view.

[0126] The first contact layer 512 is provided, for example, in common to all pixels P, and is disposed between the insulating film 517 and the photoelectric conversion layer 513. The first contact layer 512 serves to electrically separate adjacent pixels P, and the first contact layer 512 is provided with, for example, a plurality of diffusion regions 512A. By using, for the first contact layer 512, a compound semiconductor material having a band gap larger than the band gap of the compound semiconductor material constituting the photoelectric conversion layer 513, it is also possible to suppress dark current. For example, n-type InP (indium phosphide) can be used for the first contact layer 512.

[0127] The diffusion regions 512A provided in the first contact layer 512 are arranged to be spaced apart from each other. The diffusion region 512A is arranged for each pixel P, and the first electrode 511 is connected to each diffusion region 512A. The diffusion region 512A is also provided in the OPB region R1B. The diffusion region 512A is for reading out the signal charge generated in the photoelectric conversion layer 513 for each pixel P, and contains, for example, a p-type impurity. An example of the p-type impurity is Zn (zinc). In this way, a pn junction interface is formed between the diffusion region 512A and the first contact layer 512 other than the diffusion region 512A, so that adjacent pixels P are electrically isolated. The diffusion region 512A is provided, for example, in the thickness direction of the first contact layer 512, and is also provided in a part of the thickness direction of the photoelectric conversion layer 513.

[0128] The photoelectric conversion layer 513 between the first electrode 511 and the second electrode 515, more specifically, between the first contact layer 512 and the second contact layer 514, is provided, for example, in common to all pixels P. This photoelectric conversion layer 513 absorbs light of a predetermined wavelength and generates a signal charge, and is made of, for example, a compound semiconductor material such as an i-type III-V group semiconductor. Examples of the compound semiconductor material constituting the photoelectric conversion layer 513 include InGaAs (indium gallium arsenide), InAsSb (indium arsenide antimony), InAs (indium arsenide), InSb (indium antimony), and HgCdTe (mercury cadmium telluride). The photoelectric conversion layer 513 may be made of Ge (germanium). In the photoelectric conversion layer 513, for example, photoelectric conversion of light with a wavelength in the visible range to the short infrared range is performed.

[0129] The second contact layer 514 is provided, for example, in common to all the pixels P. The second contact layer 514 is provided between the photoelectric conversion layer 513 and the second electrode 515 and is in contact with them. The second contact layer 514 is a region where charges discharged from the second electrode 515 move, and is made of, for example, a compound semiconductor containing n-type impurities. The second contact layer 514 can be made of, for example, n-type InP (indium phosphide).

[0130] The second electrode 515 is provided on the second contact layer 514 (light incident side) as an electrode common to each pixel P, for example, so as to be in contact with the second contact layer 514. The second electrode 515 is for discharging charges (cathode) that are not used as signal charges among the charges generated in the photoelectric conversion layer 513. For example, when holes are read out as signal charges from the first electrode 511, electrons, for example, can be discharged through this second electrode 515. The second electrode 515 is made of a conductive film that can transmit incident light such as infrared rays. The second electrode 515 is made of, for example, ITO (Indium Tin Oxide) or ITiO (In 2 O 3 -TiO 2) or the like can be used. The second electrode 515 may be provided in a lattice shape so as to separate adjacent pixels P. This second electrode 515 can be made of a conductive material with low light transmittance.

[0131] The passivation film 516 covers the second electrode 515 from the light incident surface S1 side. The passivation film 516 may have an anti-reflection function. The passivation film 516 may be made of, for example, silicon nitride (SiN), aluminum oxide (Al 2 O 3 ), silicon oxide (SiO 2 ) and tantalum oxide (Ta 2 O 3 ) or the like can be used. The passivation film 516 has an opening 516H in the OPB region R1B. The opening 516H is provided, for example, in the shape of a frame surrounding the light receiving region ( FIG. 11A ). The opening 516H may be, for example, a rectangular or circular hole in a plan view. The conductive film 515B is electrically connected to the second electrode 515 through the opening 516H of the passivation film 516.

[0132] The insulating film 517 is provided between the first contact layer 512 and the buried layer 518, covers an end face of the first contact layer 512, an end face of the photoelectric conversion layer 513, an end face of the second contact layer 514, and an end face of the second electrode 515, and is in contact with the passivation film 516 in the peripheral region R2. The insulating film 517 is made of, for example, silicon oxide (SiO X ) or aluminum oxide (Al 2 O 3 The insulating film 517 may be formed of a laminated structure made of a plurality of films. The insulating film 517 may be formed of a silicon (Si)-based insulating material such as silicon oxynitride (SiON), carbon-containing silicon oxide (SiOC), silicon nitride (SiN), and silicon carbide (SiC). The insulating film 517 has a thickness of, for example, several tens to several hundreds of nm.

[0133] The conductive film 515B is provided across the hole H1 in the peripheral region R2 from the OPB region R1B. This conductive film 515B contacts the second electrode 515 at the opening 516H of the passivation film 516 provided in the OPB region R1B, and contacts the wiring (later-described wiring 522CB) of the readout circuit board 520 through the hole H1. This allows a voltage to be supplied from the readout circuit board 520 to the second electrode 515 through the conductive film 515B. The conductive film 515B functions as a voltage supply path to the second electrode 515 and also functions as a light-shielding film, forming the OPB region R1B. The conductive film 515B is made of a metal material including, for example, tungsten (W), aluminum (Al), titanium (Ti), molybdenum (Mo), tantalum (Ta), or copper (Cu). A passivation film may be provided on the conductive film 515B.

[0134] An adhesive layer B may be provided between the end of the second contact layer 514 and the second electrode 515. As described later, this adhesive layer B is used when forming the light receiving element 501, and serves to bond the semiconductor layer 510S to the temporary substrate. The adhesive layer B is made of, for example, tetraethoxysilane (TEOS) or silicon oxide (SiO 2 ) The adhesive layer B is provided, for example, wider than the end face of the semiconductor layer 510S, and is covered by the buried layer 518 together with the semiconductor layer 510S. An insulating film 517 is provided between the adhesive layer B and the buried layer 518.

[0135] The embedded layer 518 is intended to fill in the step between the temporary substrate and the semiconductor layer 510S in the manufacturing process of the light receiving element 501. Although details will be described later, in the present embodiment, the embedded layer 518 is formed, so that the occurrence of defects in the manufacturing process due to the step between the semiconductor layer 510S and the temporary substrate 533 can be suppressed.

[0136] The embedded layer 518 in the peripheral region R2 is provided between the wiring layer 10W and the insulating film 517 and between the wiring layer 510W and the passivation film 516, and has a thickness equal to or greater than that of the semiconductor layer 510S. Here, the embedded layer 518 is provided to surround the semiconductor layer 510S, so that a region (peripheral region R2) around the semiconductor layer 510S is formed. This allows the bonding surface S2 with the readout circuit board 520 to be provided in the peripheral region R2. If the bonding surface S2 is formed in the peripheral region R2, the thickness of the embedded layer 518 may be reduced, but it is preferable that the embedded layer 518 covers the semiconductor layer 510S in the thickness direction, and the entire end surface of the semiconductor layer 510S is covered by the embedded layer 518. By the embedded layer 518 covering the entire end surface of the semiconductor layer 510S via the insulating film 517, the intrusion of moisture into the semiconductor layer 510S can be effectively suppressed. The buried layer 518 in the element region R1 is provided between the semiconductor layer 510S and the wiring layer 510W so as to cover the first electrode 511.

[0137] The surface of the buried layer 518 on the bonding surface S2 side is flattened, and in the peripheral region R2, the wiring layer 510W is provided on the flattened surface of the buried layer 518. The buried layer 518 is made of, for example, silicon oxide (SiO X ), silicon nitride (SiN), silicon oxynitride (SiON), silicon oxide containing carbon (SiOC), silicon carbide (SiC), and other inorganic insulating materials can be used.

[0138] In the process of manufacturing the light receiving element 501, after forming the buried layer 518, the wiring layer 510W including the interlayer insulating films 519A and 519B and the contact electrode 519E is formed above the buried layer 518. The readout circuit board 520 including the wiring layer 520W is bonded to the element board 510 including the wiring layer 510W to form the light receiving element 501. At this time, the contact electrode 519E of the wiring layer 510W is connected to the contact electrode 522E of the wiring layer 520W. The contact electrodes 519E and 522E have, for example, Cu pads, and the contact electrodes 519E and 522E are connected by direct bonding of the Cu pads. When the contact electrode 519E is formed by using the CMP (Chemical Mechanical Polishing) method, the buried layer 518 arranged below the copper film to be polished is required to have a hardness that can withstand the stress during polishing. In addition, in order to directly bond the Cu pads of the contact electrodes 519E and 522E to each other, it is necessary to form the element substrate 510 and the readout circuit substrate 520 extremely flat. For this reason, it is preferable that the buried layer 518 disposed below the copper film has a hardness that can withstand the stress during polishing. Specifically, it is preferable that the material constituting the buried layer 518 is a material having a higher hardness than the sealant or organic material disposed around the die in a general semiconductor package. Examples of materials having such high hardness include inorganic insulating materials. The buried layer 518 can be formed by forming a film of this inorganic insulating material by, for example, a CVD (Chemical Vapor Deposition) method, a sputtering method, or a coating method.

[0139] The buried layer 518 is provided with holes H1 and H2 penetrating the buried layer 518. The holes H1 and H2 penetrate the wiring layer 510W together with the buried layer 518, and reach the readout circuit board 520. The holes H1 and H2 have, for example, a rectangular planar shape, and a plurality of holes H1 and H2 are provided so as to surround the element region R1 (FIG. 11A). The hole H1 is provided at a position closer to the element region R1 than the hole H2, and the sidewall and bottom surface of the hole H1 are covered with the conductive film 515B. The hole H1 is for connecting the second electrode 515 (conductive film 515B) and the wiring (later-described wiring 522CB) of the readout circuit board 520, and is provided penetrating the passivation film 516, the buried layer 518, and the wiring layer 510W.

[0140] The hole H2 is provided, for example, at a position closer to the chip end E than the hole H1. The hole H2 penetrates the passivation film 516, the embedded layer 518, and the wiring layer 510W, and reaches a pad electrode (a pad electrode 522P described later) of the readout circuit board 520. The light receiving element 501 is electrically connected to the outside through the hole H2. The holes H1 and H2 do not have to reach the readout circuit board 520. For example, the holes H1 and H2 may reach a wiring of the wiring layer 510W, and the wiring may be connected to the wiring 522CB and the pad electrode 522P of the readout circuit board 520. The holes H1 and H2 may penetrate the adhesive layer B.

[0141] The holes and electrons generated in the photoelectric conversion layer 513 are read out from the first electrode 511 and the second electrode 515. In order to perform this read operation at high speed, it is preferable to set the distance between the first electrode 511 and the second electrode 515 to a distance sufficient for photoelectric conversion but not too far apart. That is, it is preferable to reduce the thickness of the element substrate 510. For example, the distance between the first electrode 511 and the second electrode 515 or the thickness of the element substrate 510 is 10 μm or less, further 7 μm or less, and further 5 μm or less.

[0142] The semiconductor substrate 521 of the readout circuit substrate 520 faces the element substrate 510 with the wiring layer 520W and the multi-layer wiring layer 522C between them. The semiconductor substrate 521 is made of, for example, silicon (Si). A plurality of transistors are provided near the surface (surface on the wiring layer 520W side) of the semiconductor substrate 521. For example, a readout circuit (Read Out Circuit) is configured for each pixel P using the plurality of transistors. As this readout circuit, the pixel circuit 1 described in each embodiment and modification can be used. The wiring layer 520W has, for example, an interlayer insulating film 522A and an interlayer insulating film 522B in this order from the element substrate 510 side, and these interlayer insulating films 522A and 522B are provided in a laminated state. For example, a contact electrode 522E and a dummy electrode 522ED are provided in the interlayer insulating film 522A. The multi-layer wiring layer 522C is provided facing the element substrate 510 with the wiring layer 520W between them. For example, a pad electrode 522P and a plurality of wirings 522CB are provided in the multi-layer wiring layer 522C. The interlayer insulating films 522A and 522B are made of, for example, an inorganic insulating material. Examples of the inorganic insulating material include silicon nitride (SiN) and aluminum oxide (Al 2 O 3 ), silicon oxide (SiO 2 ) and hafnium oxide (HfO 2 ) etc.

[0143] The contact electrode 522E is for electrically connecting the first electrode 511 and the wiring 522CB, and is provided in the element region R1 for each pixel P. This contact electrode 522E contacts the contact electrode 519E on the bonding surface S2 of the element substrate 510. Adjacent contact electrodes 522E are electrically isolated by an interlayer insulating film 522A.

[0144] The dummy electrode 522ED provided in the peripheral region R2 is in contact with the dummy electrode 519ED on the bonding surface S2 of the element substrate 510. The dummy electrode 522ED is formed, for example, in the same process as the contact electrode 522E. The contact electrode 522E and the dummy electrode 522ED are formed, for example, of a copper (Cu) pad, and are exposed on the surface of the readout circuit substrate 520 facing the element substrate 510. That is, for example, CuCu bonding is performed between the contact electrode 519E and the contact electrode 522E, and between the dummy electrode 519ED and the dummy electrode 522ED. This makes it possible to miniaturize the pixel P.

[0145] The wiring 522CB connected to the contact electrode 519E is connected to a transistor provided near the surface of the semiconductor substrate 521, and the first electrode 511 and the readout circuit are connected for each pixel P. The wiring 522CB connected to the conductive film 515B via the hole H1 is connected to, for example, a predetermined potential. In this way, one of the charges (e.g., a hole) generated in the photoelectric conversion layer 513 is read out from the first electrode 511 to the readout circuit via the contact electrodes 519E and 522E, and the other of the charges (e.g., an electron) generated in the photoelectric conversion layer 513 is discharged from the second electrode 515 to a predetermined potential via the conductive film 515B.

[0146] The pad electrode 522P provided in the peripheral region R2 is for electrical connection to the outside. A hole H2 is provided near the chip end E of the light receiving element 501, penetrating the element substrate 510 and reaching the pad electrode 522P, and electrical connection to the outside is made through this hole H2. The connection is made by a method such as wire bonding or bumping. For example, a predetermined potential may be supplied from an external terminal arranged in the hole H2 to the second electrode 515 through the hole H2, the wiring 522CB of the readout circuit board 520, and the conductive film 515B. As a result of photoelectric conversion in the photoelectric conversion layer 513, a signal voltage read out from the first electrode 511 may be read out to a readout circuit of the semiconductor substrate 521 through the contact electrodes 519E and 522E, and output to an external terminal arranged in the hole H2 via this readout circuit. The signal voltage may be output to an external terminal via the readout circuit as well as, for example, other circuits included in the readout circuit board 520. The other circuits include, for example, a signal processing circuit and an output circuit.

[0147] The thickness of the readout circuit board 520 is preferably greater than that of the element substrate 510. For example, the thickness of the readout circuit board 520 is preferably at least twice, more preferably at least five times, more preferably at least ten times, more preferably at least ten times, more preferably at least 100 μm, more preferably at least 150 μm, more preferably at least 200 μm. The readout circuit board 520 having such a large thickness ensures the mechanical strength of the light receiving element 501. The readout circuit board 520 may include only one layer of the semiconductor substrate 521 forming the circuit, or may further include a substrate such as a support substrate in addition to the semiconductor substrate 521 forming the circuit.

[0148] 12 is a diagram illustrating a cross-sectional configuration of another light receiving element. For example, each pixel circuit 1 described in each embodiment and its modified example can be applied to the light receiving element shown in FIG.

[0149] 12, each pixel 602 in the pixel array region is divided into normal pixels 602A and charge emission pixels 602B depending on the control of the reset transistor, but since the pixel structure is the same for both normal pixels 602A and charge emission pixels 602B, they will be simply described as pixels 602. Note that the charge emission pixels 602B are arranged at the outermost side of the pixel array region.

[0150] A readout circuit of the capacitance element, reset transistor, amplifying transistor, and selection transistor of each pixel 602 is formed for each pixel on a semiconductor substrate 612 made of a single crystal material such as single crystal silicon (Si).

[0151] On the upper side of the semiconductor substrate 612, which is the light incident side, an N-type semiconductor thin film 641 is formed over the entire surface of the pixel array region. The N-type semiconductor thin film 641 is made of InGaP, InAlP, InGaAs, InAlAs, or a compound semiconductor with a chalcopyrite structure. The compound semiconductor with a chalcopyrite structure is a material that provides a high light absorption coefficient and high sensitivity over a wide wavelength range, and is preferably used as the N-type semiconductor thin film 641 for photoelectric conversion. Such a compound semiconductor with a chalcopyrite structure is made of elements surrounding IV group elements, such as Cu, Al, Ga, In, S, and Se, and examples thereof include CuGaInS-based mixed crystals, CuAlGaInS-based mixed crystals, and CuAlGaInSSe-based mixed crystals. As a readout circuit arranged on this semiconductor substrate 612, the pixel circuit 1 described in each embodiment and each modified example can be applied.

[0152] In addition to the above-mentioned compound semiconductors, the material of the N-type semiconductor thin film 641 may be amorphous silicon (Si), germanium (Ge), a quantum (Q: Quantum) dot photoelectric conversion film, an organic photoelectric conversion film, etc. Here, it is assumed that the N-type semiconductor thin film 641 is made of an InGaAs compound semiconductor.

[0153] A high-concentration P-type layer 642 constituting a pixel electrode is formed for each pixel on the lower side of the N-type semiconductor thin film 641, which is the semiconductor substrate 612 side. Between the high-concentration P-type layers 642 formed for each pixel, an N-type layer 643 is formed of a compound semiconductor such as InP as a pixel isolation region that isolates each pixel 602. In addition to functioning as a pixel isolation region, this N-type layer 643 also has the role of preventing dark current.

[0154] Meanwhile, an N-type layer 644 having a higher concentration than the N-type semiconductor thin film 641 is formed on the upper side, which is the light incident side, of the N-type semiconductor thin film 641 by using a compound semiconductor such as InP used as the pixel separation region. This high-concentration N-type layer 644 functions as a barrier layer that prevents the backflow of charges generated in the N-type semiconductor thin film 641. The material of the high-concentration N-type layer 644 can be, for example, a compound semiconductor such as InGaAs, InP, or InAlAs.

[0155] An anti-reflection film 645 is formed on the high-concentration N-type layer 644 as a barrier layer. The material of the anti-reflection film 645 is, for example, silicon nitride (SiN), hafnium oxide (HfO 2 ), aluminum oxide (Al 2 O 3 ), zirconium oxide (ZrO 2 ), tantalum oxide (Ta 2 Ta 5 ), titanium dioxide (TiO 2 ) etc. can be used.

[0156] Either the high-concentration N-type layer 644 or the anti-reflective film 645 also functions as the upper electrode of the electrodes sandwiching the N-type semiconductor thin film 641 from above and below, and a predetermined voltage Va is applied to the high-concentration N-type layer 644 or the anti-reflective film 645 as the upper electrode.

[0157] A color filter 646 and an on-chip lens 647 are further formed on the anti-reflection film 645. The color filter 646 is a filter that transmits any one of R (red), G (green), and B (blue) light (wavelength light), and is arranged in a so-called Bayer array in the pixel array region, for example.

[0158] A passivation layer 651 and an insulating layer 652 are formed below the high-concentration P-type layer 642 constituting the pixel electrode and the N-type layer 643 as a pixel isolation region. Connection electrodes 653A and 653B and a bump electrode 654 are formed so as to penetrate the passivation layer 651 and the insulating layer 652. The connection electrodes 653A and 653B and the bump electrode 654 electrically connect the high-concentration P-type layer 642 constituting the pixel electrode to a capacitance element 622 that accumulates electric charge.

[0159] The normal pixel 602A and the charge emission pixel 602B are configured as described above and have the same pixel structure. However, the normal pixel 602A and the charge emission pixel 602B differ in the method of controlling the reset transistor.

[0160] In the normal pixel 602A, the reset transistor is turned on and off based on a reset signal according to the charge generation period (light receiving period) by the photoelectric conversion unit, the reset period of the potential of the capacitive element before the start of light receiving, etc., but in the charge emitting pixel 602B, the reset transistor is controlled to be always on. As a result, the charge generated in the photoelectric conversion unit is discharged to the ground, and a constant voltage Va is always applied to the charge emitting pixel 602B.

[0161] (7. Mobile Application Examples) The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of moving body such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility device, an airplane, a drone, a ship, a robot, etc.

[0162] FIG. 13 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a moving object control system to which the technology according to the present disclosure can be applied.

[0163] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 13, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. Also, as functional configurations of the integrated control unit 12050, a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (interface) 12053 are illustrated.

[0164] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating a braking force of the vehicle.

[0165] The body system control unit 12020 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as head lamps, back lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves or signals of various switches transmitted from a portable device that replaces a key may be input to the body system control unit 12020. The body system control unit 12020 receives the input of these radio waves or signals and controls the door lock device, power window device, lamps, and the like of the vehicle.

[0166] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture an image outside the vehicle and receives the captured image. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for a person, a car, an obstacle, a sign, or characters on a road surface, based on the received image.

[0167] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal according to the amount of light received. The imaging unit 12031 can output the electrical signal as an image, or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0168] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing.

[0169] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, the steering mechanism, or the braking device based on the information inside and outside the vehicle acquired by the outside-of-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output a control command to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane departure warning, etc.

[0170] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on the driver's operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle acquired by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0171] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the outside-vehicle information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside-vehicle information detection unit 12030, and perform cooperative control for the purpose of preventing glare, such as switching from high beams to low beams.

[0172] The audio / video output unit 12052 transmits at least one output signal of audio and image to an output device capable of visually or audibly notifying information to passengers in the vehicle or the outside of the vehicle. In the example of Fig. 13, an audio speaker 12061, a display unit 12062, and an instrument panel 12063 are exemplified as the output device. The display unit 12062 may include at least one of an on-board display and a head-up display, for example.

[0173] FIG. 14 is a diagram showing an example of the installation position of the imaging unit 12031.

[0174] In FIG. 14, a vehicle 12100 has imaging units 12101, 12102, 12103, 12104, and 12105 as an imaging unit 12031.

[0175] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided at positions such as the front nose, side mirrors, rear bumper, back door, and the upper part of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided at the front nose and the imaging unit 12105 provided at the upper part of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided at the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided at the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The images of the front acquired by the imaging units 12101 and 12105 are mainly used to detect a preceding vehicle, a pedestrian, an obstacle, a traffic light, a traffic sign, a lane, or the like.

[0176] 14 shows an example of the imaging ranges of the imaging units 12101 to 12104. An imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and an imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, an overhead image of the vehicle 12100 viewed from above is obtained by superimposing the image data captured by the imaging units 12101 to 12104.

[0177] At least one of the imaging units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera made up of a plurality of imaging elements, or may be an imaging element having pixels for detecting a phase difference.

[0178] For example, the microcomputer 12051 can extract, as a preceding vehicle, a three-dimensional object that is the closest three-dimensional object on the travel path of the vehicle 12100 and travels at a predetermined speed (for example, 0 km / h or more) in approximately the same direction as the vehicle 12100, by calculating the distance to each three-dimensional object in the imaging ranges 12111 to 12114 and the change over time of this distance (relative speed with respect to the vehicle 12100) based on the distance information obtained from the imaging units 12101 to 12104. Furthermore, the microcomputer 12051 can set a vehicle distance to be secured in advance in front of the preceding vehicle, and perform automatic brake control (including follow-up stop control) and automatic acceleration control (including follow-up start control). In this way, cooperative control can be performed for the purpose of automatic driving that travels autonomously without relying on the driver's operation.

[0179] For example, the microcomputer 12051 classifies and extracts three-dimensional object data on three-dimensional objects into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from the imaging units 12101 to 12104, and can use the data for automatic obstacle avoidance. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. Then, the microcomputer 12051 determines a collision risk indicating the risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drive system control unit 12010.

[0180] At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether or not a pedestrian is present in the captured images of the imaging units 12101 to 12104. The recognition of such a pedestrian is performed, for example, by a procedure of extracting feature points in the captured images of the imaging units 12101 to 12104 as infrared cameras, and a procedure of performing pattern matching processing on a series of feature points that indicate the contour of an object to determine whether or not the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the captured images of the imaging units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular contour line for emphasis on the recognized pedestrian. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating a pedestrian at a desired position.

[0181] An example of a vehicle control system to which the technology according to the present disclosure can be applied has been described above. The technology according to the present disclosure can be applied to the imaging unit 12031 among the configurations described above. Specifically, the pixel 120 having the configurations exemplified in FIGS. 3 and 5 to 10 can be applied to the imaging unit 12031. By applying the technology according to the present disclosure to the imaging unit 12031, it is possible to obtain a captured image that is easier to see by appropriately adjusting the balance between suppression of blooming and the amount of saturation charge, thereby reducing the driver's fatigue.

[0182] (8. Application to endoscopic surgery systems) Furthermore, the technology disclosed herein may be applied to an endoscopic surgery system.

[0183] FIG. 15 is a diagram showing an example of a schematic configuration of an endoscopic surgery system to which the technology according to the present disclosure (the present technology) can be applied.

[0184] 15 shows a state in which an operator (doctor) 11131 is performing surgery on a patient 11132 on a patient bed 11133 using an endoscopic surgery system 11000. As shown in the figure, the endoscopic surgery system 11000 is composed of an endoscope 11100, other surgical tools 11110 such as an insufflation tube 11111 and an energy treatment tool 11112, a support arm device 11120 that supports the endoscope 11100, and a cart 11200 on which various devices for endoscopic surgery are mounted.

[0185] The endoscope 11100 is composed of a lens barrel 11101, a region of a predetermined length from the tip of which is inserted into a body cavity of a patient 11132, and a camera head 11102 connected to the base end of the lens barrel 11101. In the illustrated example, the endoscope 11100 is configured as a so-called rigid scope having a rigid lens barrel 11101, but the endoscope 11100 may be configured as a so-called flexible scope having a flexible lens barrel.

[0186] An opening into which an objective lens is fitted is provided at the tip of the lens barrel 11101. A light source device 11203 is connected to the endoscope 11100, and light generated by the light source device 11203 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 11101, and is irradiated via the objective lens toward an observation target in the body cavity of the patient 11132. The endoscope 11100 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0187] An optical system and an image sensor are provided inside the camera head 11102, and reflected light (observation light) from an observation target is collected on the image sensor by the optical system. The observation light is photoelectrically converted by the image sensor to generate an electrical signal corresponding to the observation light, i.e., an image signal corresponding to an observation image. The image signal is transmitted to a camera control unit (CCU) 11201 as RAW data.

[0188] The CCU 11201 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and performs overall control of the operations of the endoscope 11100 and the display device 11202. Furthermore, the CCU 11201 receives an image signal from the camera head 11102, and performs various types of image processing on the image signal, such as development processing (demosaic processing), for displaying an image based on the image signal.

[0189] Under the control of the CCU 11201, the display device 11202 displays an image based on an image signal that has been subjected to image processing by the CCU 11201.

[0190] The light source device 11203 is composed of a light source such as an LED (Light Emitting Diode), and supplies the endoscope 11100 with irradiation light when photographing an operation site or the like.

[0191] The input device 11204 is an input interface for the endoscopic surgery system 11000. A user can input various information and instructions to the endoscopic surgery system 11000 via the input device 11204. For example, the user inputs an instruction to change the imaging conditions (type of irradiated light, magnification, focal length, etc.) of the endoscope 11100.

[0192] The treatment tool control device 11205 controls the driving of the energy treatment tool 11112 for cauterizing tissue, incising, sealing blood vessels, etc. The insufflation device 11206 sends gas into the body cavity of the patient 11132 via the insufflation tube 11111 to inflate the body cavity for the purpose of securing the field of view of the endoscope 11100 and securing the working space of the surgeon. The recorder 11207 is a device capable of recording various information related to the surgery. The printer 11208 is a device capable of printing various information related to the surgery in various formats such as text, image, or graph.

[0193] The light source device 11203 that supplies irradiation light to the endoscope 11100 when photographing the surgical site can be composed of a white light source composed of, for example, an LED, a laser light source, or a combination of these. When the white light source is composed of a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, so that the white balance of the captured image can be adjusted in the light source device 11203. In this case, it is also possible to capture images corresponding to each of the RGB colors in a time-division manner by irradiating the observation object with laser light from each of the RGB laser light sources in a time-division manner and controlling the driving of the image sensor of the camera head 11102 in synchronization with the irradiation timing. According to this method, a color image can be obtained without providing a color filter to the image sensor.

[0194] The light source device 11203 may be controlled to change the intensity of the light it outputs at predetermined time intervals. The driving of the image sensor of the camera head 11102 may be controlled in synchronization with the timing of the change in the light intensity to obtain images in a time-division manner, and the images may be synthesized to generate an image with a high dynamic range that is free of so-called blackout and whiteout.

[0195] The light source device 11203 may be configured to supply light of a predetermined wavelength band corresponding to the special light observation. In the special light observation, for example, by utilizing the wavelength dependency of light absorption in body tissue, a narrow band light is irradiated compared to the irradiated light (i.e., white light) during normal observation, and a predetermined tissue such as blood vessels on the mucous membrane surface is photographed with high contrast, so-called narrow band imaging is performed. Alternatively, in the special light observation, a fluorescent observation may be performed in which an image is obtained by fluorescence generated by irradiating an excitation light. In the fluorescent observation, it is possible to irradiate an excitation light to a body tissue and observe the fluorescence from the body tissue (autofluorescence observation), or to locally inject a reagent such as indocyanine green (ICG) into the body tissue and irradiate the body tissue with excitation light corresponding to the fluorescent wavelength of the reagent to obtain a fluorescent image. The light source device 11203 may be configured to supply narrow band light and / or excitation light corresponding to such special light observation.

[0196] FIG. 16 is a block diagram showing an example of the functional configuration of the camera head 11102 and the CCU 11201 shown in FIG.

[0197] The camera head 11102 has a lens unit 11401, an imaging unit 11402, a drive unit 11403, a communication unit 11404, and a camera head control unit 11405. The CCU 11201 has a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera head 11102 and the CCU 11201 are connected to each other by a transmission cable 11400 so as to be able to communicate with each other.

[0198] The lens unit 11401 is an optical system provided at the connection portion with the lens barrel 11101. Observation light taken in from the tip of the lens barrel 11101 is guided to the camera head 11102 and enters the lens unit 11401. The lens unit 11401 is configured by combining a plurality of lenses including a zoom lens and a focus lens.

[0199] The imaging unit 11402 is composed of an imaging element. The imaging element constituting the imaging unit 11402 may be one (so-called single-plate type) or multiple (so-called multi-plate type). When the imaging unit 11402 is composed of a multi-plate type, for example, each imaging element may generate an image signal corresponding to each of RGB, and a color image may be obtained by combining the image signals. Alternatively, the imaging unit 11402 may be configured to have a pair of imaging elements for acquiring image signals for the right eye and the left eye corresponding to 3D (Dimensional) display. By performing 3D display, the surgeon 11131 can more accurately grasp the depth of the biological tissue in the surgical site. Note that when the imaging unit 11402 is composed of a multi-plate type, multiple lens units 11401 may be provided corresponding to each imaging element.

[0200] Furthermore, the imaging unit 11402 does not necessarily have to be provided in the camera head 11102. For example, the imaging unit 11402 may be provided inside the lens barrel 11101, immediately behind the objective lens.

[0201] The driving unit 11403 is configured by an actuator, and moves the zoom lens and focus lens of the lens unit 11401 by a predetermined distance along the optical axis under the control of the camera head control unit 11405. This allows the magnification and focus of the image captured by the imaging unit 11402 to be appropriately adjusted.

[0202] The communication unit 11404 is configured by a communication device for transmitting and receiving various information to and from the CCU 11201. The communication unit 11404 transmits the image signal obtained from the imaging unit 11402 to the CCU 11201 via the transmission cable 11400 as RAW data.

[0203] Furthermore, the communication unit 11404 receives a control signal for controlling the driving of the camera head 11102 from the CCU 11201, and supplies the control signal to the camera head control unit 11405. The control signal includes information on the imaging conditions, such as information specifying the frame rate of the captured image, information specifying the exposure value at the time of capturing the image, and / or information specifying the magnification and focus of the captured image.

[0204] The image capturing conditions such as the frame rate, exposure value, magnification, and focus may be appropriately specified by a user, or may be automatically set by the control unit 11413 of the CCU 11201 based on an acquired image signal. In the latter case, the endoscope 11100 is equipped with a so-called AE (Auto Exposure) function, AF (Auto Focus) function, and AWB (Auto White Balance) function.

[0205] The camera head control unit 11405 controls the driving of the camera head 11102 based on a control signal received from the CCU 11201 via the communication unit 11404.

[0206] The communication unit 11411 is configured with a communication device for transmitting and receiving various information to and from the camera head 11102. The communication unit 11411 receives an image signal transmitted from the camera head 11102 via the transmission cable 11400.

[0207] Furthermore, the communication unit 11411 transmits, to the camera head 11102, a control signal for controlling the driving of the camera head 11102. The image signal and the control signal can be transmitted by electrical communication, optical communication, or the like.

[0208] The image processing unit 11412 performs various types of image processing on the image signal, which is RAW data sent from the camera head 11102 .

[0209] The control unit 11413 performs various controls related to imaging of the surgical site etc. by the endoscope 11100 and display of the captured image obtained by imaging the surgical site etc. For example, the control unit 11413 generates a control signal for controlling the driving of the camera head 11102.

[0210] Further, the control unit 11413 causes the display device 11202 to display the captured image showing the surgical site, etc., based on the image signal that has been image-processed by the image processing unit 11412. At this time, the control unit 11413 may recognize various objects in the captured image using various image recognition techniques. For example, the control unit 11413 can recognize surgical tools such as forceps, specific living body parts, bleeding, mist when the energy treatment tool 11112 is used, etc., by detecting the shape and color of the edge of an object included in the captured image. When the control unit 11413 causes the display device 11202 to display the captured image, it may use the recognition result to superimpose various types of surgery support information on the image of the surgical site. By superimposing and presenting the surgery support information to the surgeon 11131, the burden on the surgeon 11131 can be reduced and the surgeon 11131 can proceed with the surgery reliably.

[0211] The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 is an electrical signal cable for communication of electrical signals, an optical fiber for optical communication, or a composite cable of these.

[0212] Here, in the illustrated example, communication is performed wired using a transmission cable 11400, but communication between the camera head 11102 and the CCU 11201 may also be performed wirelessly.

[0213] An example of an endoscopic surgery system to which the technology according to the present disclosure can be applied has been described above. The technology according to the present disclosure can be applied to the endoscope 11100 and the imaging unit 11402 of the camera head 11102 among the configurations described above. Specifically, the pixel 120 having the configuration exemplified in Figs. 3, 5 to 10 can be applied to the endoscope 11100 and the imaging unit 11402 of the camera head 11102. By applying the technology according to the present disclosure to the endoscope 11100 and the imaging unit 11402 of the camera head 11102, a clearer image of the surgical site can be obtained by appropriately adjusting the balance between suppression of blooming and the amount of saturation charge, so that the surgeon can reliably confirm the surgical site.

[0214] Although an endoscopic surgery system has been described as an example here, the technology disclosed herein may also be applied to other systems, such as a microsurgery system.

[0215] Although the embodiments of the present disclosure have been described above, the technical scope of the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present disclosure. In addition, components of different embodiments and modifications may be appropriately combined.

[0216] It should be noted that the effects described in this specification are merely examples and are not limiting, and other effects may also be obtained.

[0217] The present technology can also be configured as follows.

[0218] (1) A photoelectric conversion unit that generates photocharges; a first charge holding unit connected to the photoelectric conversion unit and holding photocharges generated by the photoelectric conversion unit; a first transistor for discharging the photocharge held in the first charge holding portion to the outside; a voltage control unit that controls a voltage value of an off voltage that is applied to a gate of the first transistor when the first transistor is turned off; A solid-state imaging device comprising: (2) a second charge holding section that holds the photocharges transferred from the first charge holding section; a second transistor disposed on a wiring connecting the first charge retention portion and the second charge retention portion; a third transistor disposed on a wiring connecting the second charge storage unit and a constant voltage source; a fourth transistor that outputs a pixel signal having a voltage value corresponding to the amount of the photocharges held in the second charge holding portion to a signal line; a fifth transistor disposed on a wiring connecting the fourth transistor and the signal line; The solid-state imaging device according to (1) above, further comprising: (3) The photoelectric conversion portion includes any one of InGaAs (indium gallium arsenide), InAsSb (indium arsenide antimony), InAs (indium arsenide), InSb (indium antimony), HgCdTe (mercury cadmium telluride), Ge (germanium), quantum dots, and an organic compound. The first transistor is a P-type MOS (Metal Oxide Semiconductor) transistor. The solid-state imaging device according to (1) or (2). (4) the photoelectric conversion unit is a photodiode, The first transistor is an N-type MOS transistor. The solid-state imaging device according to (1) or (2). (5) The solid-state imaging device according to any one of (1) to (4), wherein an electrode extending from the photoelectric conversion section and an electrode extending from the first charge holding section are directly joined to each other and are electrically connected to each other. (6) The solid-state imaging device according to any one of (1) to (4), wherein a terminal extending from the photoelectric conversion portion and a terminal extending from the first charge holding portion are connected and electrically conductive by a bump electrode. (7) a feedback control unit that controls a voltage value of a voltage output from a power supply and applies the voltage value to the gate of the first transistor, The solid-state imaging device according to any one of (1) to (6), wherein the voltage control unit changes the voltage value of the off voltage by outputting information on a gate voltage to the feedback control unit. (8) The solid-state imaging device according to any one of (1) to (6), wherein the voltage control unit receives an input of a supply voltage whose voltage value has been switched by an external power supply, and changes the voltage value of the off voltage using the supply voltage. (9) a pixel array section in which a plurality of pixels are arranged in rows and columns; A drive circuit that drives a pixel to be read out of the plurality of pixels; a processing circuit that reads out pixel signals from the pixels to be read out that are driven by the drive circuit; a control unit for controlling the drive circuit and the processing circuit; The solid-state imaging device according to any one of (1) to (8), comprising: (10) The solid-state imaging device according to (9), wherein the voltage control unit changes the voltage value of the off voltage for each of one or more rows in the pixel array unit. (11) The pixel array portion is divided into a plurality of regions, The voltage control unit changes the voltage value of the off-voltage for each of the plurality of regions. The solid-state imaging device according to (9) above. (12) a plurality of buffers provided for each of the one or more rows, each buffer holding a voltage to be applied to the gate of the first transistor; The voltage control unit controls a timing for supplying the voltages held by each of the plurality of buffers to one or more of the rows. The solid-state imaging device according to any one of (1) to (11) above. (13) A solid-state imaging device; an optical system that forms an image of incident light on a light receiving surface of the solid-state imaging device; A processor for controlling the solid-state imaging device; Equipped with The solid-state imaging device includes: A photoelectric conversion unit that generates photocharges; a first charge holding unit connected to the photoelectric conversion unit and holding photocharges generated by the photoelectric conversion unit; a first transistor for discharging the photocharge held in the first charge holding portion to the outside; a voltage control unit that controls a voltage value of an off voltage that is applied to a gate of the first transistor when turning off the first transistor; Electronic equipment equipped with [Explanation of symbols]

[0219] 1 Pixel circuit 2. Voltage control circuit 10 Photoelectric conversion film 11 Reset transistor 12 Amplifying transistor 13 Select transistor 14 Transfer transistor 15 Emission transistor 16, 17 Capacitor 20 Floating Diffusion (FD) 21 Sense Node (SN) 100 Electronic equipment 101 Imaging lens 102 Image Sensor 103 Processors 104 Storage section 111 Bias voltage source 112 Power supply 113 Feedback control section 114 Voltage control section 115 Buffer 116 External power supply 120 pixels 121 pixel array 122 Vertical drive circuit 123 Column Processing Circuit 124 Horizontal drive circuit 125 System Control Unit 126 Signal Processing Section 127 Data Storage Unit 150 Row control circuit

Claims

1. A photoelectric conversion unit that generates photocharges; a first charge holding unit connected to the photoelectric conversion unit and holding photocharges generated by the photoelectric conversion unit; a first transistor for discharging the photocharge held in the first charge holding portion to an outside; a voltage control unit that controls a voltage value of an off voltage that is applied to a gate of the first transistor when turning off the first transistor; a feedback control unit that controls a voltage value of a voltage output from a power supply and applies the voltage value to the gate of the first transistor; Equipped with The voltage control unit changes the voltage value of the off-voltage by outputting information about a gate voltage to the feedback control unit.

2. A photoelectric conversion unit that generates photocharges; a first charge holding unit connected to the photoelectric conversion unit and holding photocharges generated by the photoelectric conversion unit; a first transistor for discharging the photocharge held in the first charge holding portion to an outside; a voltage control unit that controls a voltage value of an off voltage that is applied to a gate of the first transistor when turning off the first transistor; a pixel array section in which a plurality of pixels are arranged in rows and columns; A drive circuit that drives a pixel to be read out of the plurality of pixels; a processing circuit that reads out pixel signals from the pixels to be read out that are driven by the drive circuit; a control unit for controlling the drive circuit and the processing circuit; Equipped with The voltage control unit changes the voltage value of the off-voltage for each of one or more rows in the pixel array unit.

3. A photoelectric conversion unit that generates photocharges; a first charge holding unit connected to the photoelectric conversion unit and holding photocharges generated by the photoelectric conversion unit; a first transistor for discharging the photocharge held in the first charge holding portion to an outside; a voltage control unit that controls a voltage value of an off voltage that is applied to a gate of the first transistor when turning off the first transistor; a pixel array section in which a plurality of pixels are arranged in rows and columns; A drive circuit that drives a pixel to be read out of the plurality of pixels; a processing circuit that reads out pixel signals from the pixels to be read out that are driven by the drive circuit; a control unit for controlling the drive circuit and the processing circuit; Equipped with The pixel array portion is divided into a plurality of regions, The voltage control unit changes the voltage value of the off-voltage for each of the multiple regions.

4. A photoelectric conversion unit that generates photocharges; a first charge holding unit connected to the photoelectric conversion unit and holding photocharges generated by the photoelectric conversion unit; a first transistor for discharging the photocharge held in the first charge holding portion to an outside; a voltage control unit that controls a voltage value of an off voltage that is applied to a gate of the first transistor when turning off the first transistor; a plurality of buffers provided for each of one or a plurality of rows, each buffer holding a voltage to be applied to the gate of the first transistor; Equipped with The voltage control unit controls a timing at which the voltages held in the respective buffers are supplied to one or more of the rows.

5. a second charge holding section that holds the photocharges transferred from the first charge holding section; a second transistor disposed on a wiring connecting the first charge retention portion and the second charge retention portion; a third transistor disposed on a wiring connecting the second charge storage unit and a constant voltage source; a fourth transistor that outputs a pixel signal having a voltage value corresponding to the amount of the photocharges held in the second charge holding portion to a signal line; a fifth transistor disposed on a wiring connecting the fourth transistor and the signal line; The solid-state imaging device according to claim 1 , further comprising:

6. The photoelectric conversion portion includes any one of InGaAs (indium gallium arsenide), InAsSb (indium arsenide antimony), InAs (indium arsenide), InSb (indium antimony), HgCdTe (mercury cadmium tellurium), Ge (germanium), quantum dots, and an organic compound. The first transistor is a P-type MOS (Metal Oxide Semiconductor) transistor. The solid-state imaging device according to claim 1 .

7. the photoelectric conversion unit is a photodiode, The first transistor is an N-type MOS transistor. The solid-state imaging device according to claim 1 .

8. The solid-state imaging device according to claim 1 , wherein an electrode extending from the photoelectric conversion portion and an electrode extending from the first charge holding portion are directly joined and electrically connected to each other.

9. The solid-state imaging device according to claim 1 , wherein a terminal extending from the photoelectric conversion portion and a terminal extending from the first charge holding portion are connected and electrically connected by a bump electrode.

10. A solid-state imaging device; an optical system that forms an image of incident light on a light receiving surface of the solid-state imaging device; A processor for controlling the solid-state imaging device; Equipped with The solid-state imaging device includes: A photoelectric conversion unit that generates photocharges; a first charge holding unit connected to the photoelectric conversion unit and holding photocharges generated by the photoelectric conversion unit; a first transistor for discharging the photocharge held in the first charge holding portion to an outside; a voltage control unit that controls a voltage value of an off voltage that is applied to a gate of the first transistor when turning off the first transistor; a feedback control unit that controls a voltage value of a voltage output from a power supply and applies the voltage value to the gate of the first transistor; Equipped with The voltage control unit changes the voltage value of the off-voltage by outputting information about a gate voltage to the feedback control unit.

11. A solid-state imaging device; an optical system that forms an image of incident light on a light receiving surface of the solid-state imaging device; A processor for controlling the solid-state imaging device; Equipped with The solid-state imaging device includes: A photoelectric conversion unit that generates photocharges; a first charge holding unit connected to the photoelectric conversion unit and holding photocharges generated by the photoelectric conversion unit; a first transistor for discharging the photocharge held in the first charge holding portion to an outside; a voltage control unit that controls a voltage value of an off voltage that is applied to a gate of the first transistor when turning off the first transistor; a pixel array section in which a plurality of pixels are arranged in rows and columns; A drive circuit that drives a pixel to be read out of the plurality of pixels; a processing circuit that reads out pixel signals from the pixels to be read out that are driven by the drive circuit; a control unit for controlling the drive circuit and the processing circuit; Equipped with The voltage control unit changes the voltage value of the off voltage for each of one or more rows in the pixel array unit.

12. A solid-state imaging device; an optical system that forms an image of incident light on a light receiving surface of the solid-state imaging device; A processor for controlling the solid-state imaging device; Equipped with The solid-state imaging device includes: A photoelectric conversion unit that generates photocharges; a first charge holding unit connected to the photoelectric conversion unit and holding photocharges generated by the photoelectric conversion unit; a first transistor for discharging the photocharge held in the first charge holding portion to an outside; a voltage control unit that controls a voltage value of an off voltage that is applied to a gate of the first transistor when turning off the first transistor; a pixel array section in which a plurality of pixels are arranged in rows and columns; A drive circuit that drives a pixel to be read out of the plurality of pixels; a processing circuit that reads out pixel signals from the pixels to be read out that are driven by the drive circuit; a control unit for controlling the drive circuit and the processing circuit; Equipped with The pixel array portion is divided into a plurality of regions, The voltage control unit changes the voltage value of the off-voltage for each of the multiple regions.

13. A solid-state imaging device; an optical system that forms an image of incident light on a light receiving surface of the solid-state imaging device; A processor for controlling the solid-state imaging device; Equipped with The solid-state imaging device includes: A photoelectric conversion unit that generates photocharges; a first charge holding unit connected to the photoelectric conversion unit and holding photocharges generated by the photoelectric conversion unit; a first transistor for discharging the photocharge held in the first charge holding portion to an outside; a voltage control unit that controls a voltage value of an off voltage that is applied to a gate of the first transistor when turning off the first transistor; a plurality of buffers provided for each of one or a plurality of rows, each buffer holding a voltage to be applied to the gate of the first transistor; Equipped with The voltage control unit is an electronic device that controls the timing at which the voltages held in each of the plurality of buffers are supplied to one or more of the rows.

Images