Photodetector and photodetection system

Abstract

There is provided a photodetector. The photodetector according to an embodiment of the present disclosure includes a first substrate, a second substrate, and an optical circuit. The first substrate includes a photoelectric conversion element that photoelectrically converts light. The second substrate includes at least a portion of a processing circuit configured to execute signal processing of a first signal generated on a basis of electric charge converted by the photoelectric conversion element. The second substrate is stacked on the first substrate. The optical circuit is configured to output a first optical signal based on the first signal.

Description

PHOTODETECTOR AND PHOTODETECTION SYSTEMCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of Japanese Priority Patent Application JP2024-197445 filed November 12, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a photodetector and a photodetection system.

[0003] An imaging device has been proposed which includes; an imaging section that photoelectrically convert light received via a lens; and a transmission section that transmits data of each pixel supplied from the imaging section to a DSP (Digital Signal Processor) via a transmission path (lane) (PTL 1).

[0004] [PTL 1] Japanese Unexamined Patent Application Publication No. 2012-120158Summary

[0005] It is desired for a photodetector to enable appropriate communication.

[0006] It is desirable to provide a photodetector that enables suitable communication.

[0007] A photodetector according to an embodiment of the present disclosure includes a first substrate, a second substrate, and an optical circuit. The first substrate includes a photoelectric conversion element that photoelectrically converts light. The second substrate includes at least a portion of a processing circuit configured to execute signal processing of a first signal generated on a basis of electric charge converted by the photoelectric conversion element. The second substrate is stacked on the first substrate. The optical circuit is configured to output a first optical signal based on the first signal. A photodetection system according to an embodiment of the present disclosure includes a photodetector and an external device. The photodetector includes a first substrate, a second substrate, and an optical circuit. The first substrate includes a photoelectric conversion element that photoelectrically converts light. The second substrate includes at least a portion of a processing circuit configured to execute signal processing of a first signal generated on a basis of electric charge converted by the photoelectric conversion element. The second substrate is stacked on the first substrate. The optical circuit is configured to transmit, to the external device, a first optical signal based on the first signal.

[0008] Fig. 1 is a block diagram illustrating an example of a schematic configuration of an imaging device which is an example of a photodetector according to an embodiment of the present disclosure.Fig. 2 is a diagram illustrating an example of a pixel section of the imaging device according to an embodiment of the present disclosure.Fig. 3 is a diagram illustrating an example of a circuit configuration of a pixel of the imaging device according to an embodiment of the present disclosure.Fig. 4 is a diagram illustrating another example of the circuit configuration of pixels of the imaging device according to an embodiment of the present disclosure.Fig. 5 is a diagram illustrating an example of a cross-sectional configuration of the imaging device according to an embodiment of the present disclosure.Fig. 6 is a diagram illustrating an example of a cross-sectional configuration of the imaging device according to an embodiment of the present disclosure.Fig. 7 is a diagram illustrating an example of a cross-sectional configuration of the imaging device according to an embodiment of the present disclosure.Fig. 8 is an explanatory diagram of a layout example of the imaging device according to an embodiment of the present disclosure.Fig. 9 is an explanatory diagram of a configuration example of an optical circuit of the imaging device according to an embodiment of the present disclosure.Fig. 10 is an explanatory diagram of another configuration example of the optical circuit of the imaging device according to an embodiment of the present disclosure.Fig. 11 is an explanatory diagram of a configuration example of the optical circuit of the imaging device according to an embodiment of the present disclosure.Fig. 12 is an explanatory diagram of a configuration example of the optical circuit of the imaging device according to an embodiment of the present disclosure.Fig. 13 is an explanatory diagram of another layout example of the imaging device according to an embodiment of the present disclosure.Fig. 14 is an explanatory diagram of a configuration example of a photodetection system according to an embodiment of the present disclosure.Fig. 15 is an explanatory diagram of a configuration example of the photodetection system according to an embodiment of the present disclosure.Fig. 16 is an explanatory diagram of another configuration example of the photodetection system according to an embodiment of the present disclosure.Fig. 17 is an explanatory diagram of another configuration example of the photodetection system according to an embodiment of the present disclosure.Fig. 18A is a diagram illustrating an example of a method of manufacturing the imaging device according to an embodiment of the present disclosure.Fig. 18B is a diagram illustrating an example of the method of manufacturing the imaging device according to an embodiment of the present disclosure.Fig. 18C is a diagram illustrating an example of the method of manufacturing the imaging device according to an embodiment of the present disclosure.Fig. 18D is a diagram illustrating an example of the method of manufacturing the imaging device according to an embodiment of the present disclosure.Fig. 18E is a diagram illustrating an example of the method of manufacturing the imaging device according to an embodiment of the present disclosure.Fig. 18F is a diagram illustrating an example of the method of manufacturing the imaging device according to an embodiment of the present disclosure.Fig. 18G is a diagram illustrating an example of the method of manufacturing the imaging device according to an embodiment of the present disclosure.Fig. 18H is a diagram illustrating an example of the method of manufacturing the imaging device according to an embodiment of the present disclosure.Fig. 19 is an explanatory diagram of a configuration example of an imaging device according to Modification Example 1 of the present disclosure.Fig. 20 is an explanatory diagram of a configuration example of the imaging device according to Modification Example 1 of the present disclosure.Fig. 21 is an explanatory diagram of another configuration example of the imaging device according to Modification Example 1 of the present disclosure.Fig. 22 is an explanatory diagram of a configuration example of an imaging device according to Modification Example 2 of the present disclosure.Fig. 23 is an explanatory diagram of a layout example of the imaging device according to Modification Example 2 of the present disclosure.Fig. 24 is an explanatory diagram of a configuration example of an imaging device according to Modification Example 3 of the present disclosure.Fig. 25 is an explanatory diagram of a configuration example of an imaging device according to Modification Example 4 of the present disclosure.Fig. 26 is an explanatory diagram of a configuration example of an imaging device according to Modification Example 5 of the present disclosure.Fig. 27 is an explanatory diagram of a configuration example of the imaging device according to Modification Example 5 of the present disclosure.Fig. 28 is an explanatory diagram of a layout example of the imaging device according to Modification Example 5 of the present disclosure.Fig. 29 is an explanatory diagram of another configuration example of the imaging device according to Modification Example 5 of the present disclosure.Fig. 30 is an explanatory diagram of another configuration example of the imaging device according to Modification Example 5 of the present disclosure.Fig. 31 is an explanatory diagram of a configuration example of an imaging device according to Modification Example 6 of the present disclosure.Fig. 32 is an explanatory diagram of a configuration example of the imaging device according to Modification Example 6 of the present disclosure.Fig. 33 is an explanatory diagram of a configuration example of an imaging device according to Modification Example 7 of the present disclosure.Fig. 34 is an explanatory diagram of a configuration example of the imaging device according to Modification Example 7 of the present disclosure.Fig. 35 is an explanatory diagram of another configuration example of the imaging device according to Modification Example 7 of the present disclosure.Fig. 36 is an explanatory diagram of another configuration example of the imaging device according to Modification Example 7 of the present disclosure.Fig. 37 is an explanatory diagram of another configuration example of the imaging device according to Modification Example 7 of the present disclosure.Fig. 38 is an explanatory diagram of another configuration example of the imaging device according to Modification Example 7 of the present disclosure.Fig. 39 is a block diagram illustrating a configuration example of an electronic apparatus including the imaging device.Fig. 40 is a block diagram illustrating another configuration example of the electronic apparatus including the imaging device.Fig. 41 is a block diagram depicting an example of schematic configuration of a vehicle control system.Fig. 42 is a diagram of assistance in explaining an example of installation positions of an outside-vehicle information detecting section and an imaging section.Fig. 43 is a block diagram depicting another example of the schematic configuration of the vehicle control system.Fig. 44 is a view depicting an example of a schematic configuration of an endoscopic surgery system.Fig. 45 is a block diagram depicting an example of a functional configuration of a camera head and a camera control unit (CCU).Fig. 46 is a block diagram depicting another example of the functional configuration of the camera head and the camera control unit (CCU).

[0009] Hereinafter, description is given in detail of embodiments of the present disclosure with reference to the drawings. It is to be noted that the description is given in the following order. 1. Embodiment 2. Modification Examples 3. Application Example 4. Practical Application Examples <1. Embodiment>

[0010] Fig. 1 is a block diagram illustrating an example of a schematic configuration of an imaging device which is an example of a photodetector according to an embodiment of the present disclosure. Fig. 2 is a diagram illustrating an example of a pixel section of the imaging device according to the embodiment. The photodetector is a device that is able to detect incident light. An imaging device 1, which is an example of a photodetector, includes a plurality of pixels P each including a photoelectric conversion section, and is configured to photoelectrically convert incident light and generate a signal.

[0011] As an example, the imaging device 1 receives light transmitted through an optical system (unillustrated) including an optical lens, and generates a signal. The imaging device 1 is configured using, for example, a substrate (e.g., a semiconductor substrate such as an Si (silicon) substrate or an SOI (Silicon On Insulator) substrate) provided with the photoelectric conversion section of each of the pixels P.

[0012] The imaging device 1 includes a structure (stacked structure) configured by stacking a plurality of substrates, as described later. The imaging device 1 includes, for example, a photonic integrated circuit (PIC: Photonic Integrated Circuit). The imaging device 1 may be manufactured by using a silicon-containing substrate (such as a silicon substrate or an SOI substrate) and utilizing a Silicon Photonics technology.

[0013] The photoelectric conversion section of the pixel P is, for example, a photodiode (PD), and is configured to be able to photoelectrically convert light. The photoelectric conversion section of each of the pixels P can also be referred to as a photoelectric conversion element or a photoelectric conversion region. As in the example illustrated in Fig. 1 or 2, the imaging device 1 includes a region (a pixel section 100) in which the plurality of pixels P is provided. The imaging device 1 includes, as an imaging area, for example, the pixel section 100 in which the plurality of pixels P is two-dimensionally arranged in matrix.

[0014] The imaging device 1 takes in incident light (image light) from a subject, which is a measurement target, via the optical system including the optical lens. The imaging device 1 captures an image of the subject formed by the optical lens. The imaging device 1 may photoelectrically convert received light (e.g., visible light, infrared rays, etc.) and generate a pixel signal. The imaging device 1, which is a photodetector, is a device that is able to receive light and generate a signal. The imaging device 1 can also be referred to as a light-receiving device.

[0015] As an example, the imaging device 1 (photodetector) is configured as an image sensor. The imaging device 1 is, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor, a CCD (Charge Coupled Device) image sensor, or the like. The imaging device 1 is usable for various electronic apparatuses such as a digital still camera, a video camera, and a mobile phone.

[0016] It is to be noted that, as illustrated in Fig. 2, a direction in which light from the subject, as the measurement target, is incident is defined as a Z-axis direction; a right-left direction on the sheet orthogonal to the Z-axis direction is defined as an X-axis direction; and an up-down direction on the sheet orthogonal to the Z-axis direction and the X-axis direction is defined as a Y-axis direction. In the following drawings, the arrow directions in Fig. 2 may be used, in some cases, as a standard to express directions. <Schematic Configuration of Imaging Device>

[0017] As an example, the imaging device 1 includes the pixel section 100, a pixel control circuit 105, a processing circuit 200, and an optical circuit 300, as in the example illustrated in Fig. 1. In addition, the imaging device 1 is provided with, for example, a plurality of control lines L1 and a plurality of signal lines L2. The pixel section 100 is a pixel array in which the plurality of pixels P is arranged. It is to be noted that the number and arrangement of the pixels P provided in the pixel section 100 (i.e., pixel array) are changeable as appropriate.

[0018] The control line L1 is a signal line that is able to convey a signal to control the pixel P, and is coupled to the pixel control circuit 105 and the pixel P of the pixel section 100. The plurality of control lines L1 is wired for respective pixel rows configured by the plurality of pixels P arranged in a horizontal direction (row direction) in the pixel section 100. The control line L1 is configured to transmit a control signal to read a signal from the pixel P.

[0019] As an example, the plurality of control lines L1 for the respective pixel rows of the imaging device 1 includes wiring that transmits a signal to control a transfer transistor, wiring that transmits a signal to control a selection transistor, wiring that transmits a signal to control a reset transistor, and the like. The control line L1 can also be referred to as a drive line (or a pixel drive line) that transmits a signal to drive the pixel P.

[0020] The signal line L2 is a signal line that is able to convey a signal from the pixel P, and is coupled to the pixels P of the pixel section 100 and the processing circuit 200. In the pixel section 100, for example, one signal line L2 or the plurality of signal lines L2 is wired for each pixel column or respective pixel columns configured by the plurality of pixels P arranged in a vertical direction (column direction). The signal line L2 is electrically coupled to the pixel P, and is configured to be able to transmit a signal outputted from the pixel P.

[0021] In the imaging device 1, the plurality of signal lines L2 may be provided for one pixel column. For example, the imaging device 1 includes the plurality of signal lines L2 for each pixel column including the plurality of pixels P. The number and arrangement of each of the control line L1 and the signal line L2 in the imaging device 1 are not limited to the illustrated examples, and are changeable as appropriate.

[0022] The pixel control circuit 105 is configured to be able to control each of the pixels P of the pixel section 100. The pixel control circuit 105 (pixel control section) is configured by a plurality of circuits including a buffer, a shift register, an address decoder, and the like, for example. The pixel control circuit 105 generates a signal for controlling the pixel P, and outputs the generated signal to each of the pixels P of the pixel section 100 via the control line L1.

[0023] The pixel control circuit 105 generates, for example, a signal to control the pixel P, such as a signal to control the transfer transistor of the pixel P, a signal to control the selection transistor, and a signal to control the reset transistor, and supplies the generated signal to each of the pixels P by the control line L1. The pixel control circuit 105 may execute a control to read a pixel signal from each of the pixels P. The pixel control circuit 105 can also be referred to as a pixel drive circuit (pixel drive section) configured to be able to drive each of the pixels P.

[0024] The processing circuit 200 is a signal processing circuit (signal processing section), and is configured to be able to execute signal processing. The processing circuit 200 includes an AD (Analog Digital) conversion circuit, and is configured to be able to execute signal processing of an inputted pixel signal. The processing circuit 200 includes, for example, a load circuit, an AD conversion circuit 20, a horizontal selection switch, and the like. As an example, the load circuit is configured by a current source that is able to supply a current to an amplification transistor of the pixel P. As an example, the load circuit constitutes a source follower circuit together with the amplification transistor of the pixel P.

[0025] The processing circuit 200 may include a signal amplification circuit configured to be able to amplify a pixel signal read from the pixel P via the signal line L2. The load circuit, the amplification circuit, the AD conversion circuit 20, and the like are provided for each of the plurality of signal lines L2, for example. In the imaging device 1, the load circuit, the signal amplification circuit, the AD conversion circuit 20, and the like may be provided for each pixel column of the pixel section 100. The AD conversion circuit 20 is an ADC (Analog to Digital Converter).

[0026] The AD conversion circuit 20 is configured to be able to execute AD conversion, and converts an inputted analog signal into a digital signal. The AD conversion circuit 20 (AD conversion section) performs AD conversion processing on a pixel signal, which is an analog signal, inputted from each of the pixels P via the signal line L2. As an example, the AD conversion circuit 20 includes a comparison circuit (comparator circuit) and a counter, and converts an inputted pixel signal into a digital signal of a predetermined bit number.

[0027] The processing circuit 200 includes a plurality of logic circuits, and is configured by, for example, a circuit that implements various types of signal processing on an inputted pixel signal. The processing circuit 200 includes an arithmetic circuit, a memory circuit, and the like. As an example, the processing circuit 200 may execute signal processing on a pixel signal and output a processed pixel signal. The processing circuit 200 may perform various types of signal processing, such as noise reduction processing and interpolation processing.

[0028] The signal outputted from each of the pixels P of the pixel section 100 is inputted to the processing circuit 200 via the signal line L2. The processing circuit 200 may perform, for example, signal processing such as CDS (Correlated Double Sampling: correlated double sampling) and AD conversion of a signal of the pixel P. The signal of each of the pixels P transmitted by each of the signal lines L2 is subjected to signal processing by the processing circuit 200, and is outputted to the optical circuit 300.

[0029] The processing circuit 200 is also a control circuit (control section), and is configured to be able to control each section of the imaging device 1. The processing circuit 200 may receive a clock supplied from the outside, data commanding an operation mode, or the like, and output data such as internal information on the imaging device 1. The processing circuit 200 includes, for example, a timing generator configured to be able to generate various timing signals.

[0030] The processing circuit 200 controls driving of the pixel control circuit 105, the optical circuit 300, and the like on the basis of the various timing signals (such as pulse signals or clock signals) generated by the timing generator. The processing circuit 200 may include circuits such as a PLL (Phase Locked Loop), a DAC (Digital to Analog Converter), and the like. It is to be noted that the processing circuit 200 may include at least a portion of the pixel control circuit 105.

[0031] The optical circuit 300 is configured to be able to convert an electric signal into an optical signal and output the optical signal. The optical circuit 300 includes, for example, a modulator and a waveguide, and is configured to be able to output (transmit) an optical signal based on a pixel signal. For example, a pixel signal of each of the pixels P having been subjected to the signal processing is inputted to the optical circuit 300 from the processing circuit 200.

[0032] The optical circuit 300 is configured to convert a pixel signal, which is an electric signal, inputted from the processing circuit 200 into an optical signal, and output the pixel signal converted into the optical signal to the outside. For example, the optical circuit 300 may generate an optical signal modulated on the basis of the pixel signal, which is a digital signal, inputted from the processing circuit 200, and output the generated optical signal to an external device (as an example, an image processor). <Configuration of Pixel>

[0033] Fig. 3 is a diagram illustrating an example of a circuit configuration of the pixel of the imaging device according to the embodiment. The pixel P includes a photoelectric conversion section 11, a transistor TG, a floating diffusion FD, and a readout circuit 15. The photoelectric conversion section 11 is configured to receive light and generate a signal. The photoelectric conversion section 11 is configured to be able to generate electric charge by photoelectric conversion.

[0034] In the example illustrated in Fig. 3, the photoelectric conversion section 11 is a photodiode (PD), and converts incident light into electric charge. The photoelectric conversion section 11 may perform photoelectric conversion to generate electric charge corresponding to a received light amount. The photoelectric conversion section 11 is a photoelectric conversion element, and can also be referred to as a light-receiving element. The readout circuit 15 is configured to be able to output a signal based on photoelectrically converted electric charge.

[0035] The transistor TG is configured to be able to transfer the electric charge photoelectrically converted by the photoelectric conversion section 11 to the floating diffusion FD. The transistor TG is controlled by a signal STG, and electrically couples or decouples the photoelectric conversion section 11 and the floating diffusion FD to or from each other. The transistor TG is a transfer transistor. The transistor TG may transfer the electric charge photoelectrically converted by and accumulated in the photoelectric conversion section 11 to the floating diffusion FD.

[0036] The floating diffusion FD is an accumulation section, and is configured to be able to accumulate the transferred electric charge. The floating diffusion FD may accumulate the electric charge photoelectrically converted by the photoelectric conversion section 11. The floating diffusion FD accumulates the transferred electric charge, and converts the electric charge into a voltage corresponding to a capacitance of the floating diffusion FD. It is to be noted that the floating diffusion FD can also be referred to as a holding section that is able to hold electric charge.

[0037] As an example, the readout circuit 15 includes a transistor AMP, a transistor SEL, and a transistor RST. The readout circuit 15 may read a pixel signal based on the electric charge photoelectrically converted by the photoelectric conversion section 11 (i.e., photoelectric conversion region). It is to be noted that the readout circuit 15 may include the floating diffusion FD. In addition, the readout circuit 15 may include the transistor TG.

[0038] The transistor AMP is configured to generate and output a signal based on the electric charge accumulated in the floating diffusion FD. The transistor AMP is an amplification transistor. The transistor AMP may generate and output a signal based on the electric charge converted by the photoelectric conversion section 11.

[0039] A gate of the transistor AMP is electrically coupled to the floating diffusion FD, and receives an input of the voltage converted by the floating diffusion FD. A drain of the transistor AMP is coupled to a power supply line to be supplied with a power supply voltage (a power supply voltage VDD in the example illustrated in Fig. 3), for example.

[0040] A source of the transistor AMP is coupled to the signal line L2 via the transistor SEL, for example. The transistor AMP is configured to generate a signal based on the electric charge accumulated in the floating diffusion FD, i.e., a signal based on the voltage of the floating diffusion FD and to output the generated signal to the signal line L2.

[0041] The transistor SEL is configured to be able to control the output of the pixel signal. The transistor SEL is electrically coupled in series to the transistor AMP, for example, as in the example illustrated in Fig. 3. The transistor SEL is controlled by a signal SSEL, and is configured to be able to output the signal from the transistor AMP to the signal line L2. The transistor SEL may control an output timing of the pixel signal. The transistor SEL is a selection transistor.

[0042] The transistor SEL is configured to be able to output the signal based on the electric charge converted by the photoelectric conversion section 11. The transistor SEL may output the pixel signal of the pixel P to the signal line L2. It is to be noted that the transistor SEL may be electrically coupled in series between the power supply line to be supplied with the power supply voltage (power supply voltage VDD in the example illustrated in Fig. 3) and the transistor AMP. In addition, the transistor SEL may be omitted as needed.

[0043] The transistor RST is configured to be able to reset the voltage of the floating diffusion FD. In the example illustrated in Fig. 3, the transistor RST is electrically coupled to the power supply line to be supplied with the power supply voltage VDD, and is configured to be able to reset the electric charge of the pixel P. The transistor RST is a reset transistor.

[0044] The transistor RST may be controlled by a signal SRST to reset the electric charge accumulated in the floating diffusion FD and to reset the voltage of the floating diffusion FD. For example, the transistor RST electrically couples the power supply line and the floating diffusion FD to each other, and discharges the electric charge accumulated in the floating diffusion FD. It is to be noted that the transistor RST may reset the electric charge accumulated in the photoelectric conversion section 11 via the transistor TG.

[0045] It is to be noted that the readout circuit 15 may be configured to be able to change a conversion gain (i.e., conversion efficiency) upon conversion of electric charge into a voltage. For example, the readout circuit 15 may include a transistor (switching transistor) to be used for setting of the conversion gain. As an example, the switching transistor is electrically coupled between the floating diffusion FD and the transistor RST.

[0046] The switching transistor coming into an ON state in the readout circuit 15 increases a capacitance to be added to the floating diffusion FD of the pixel P, thus switching the conversion gain (conversion efficiency) upon conversion of the electric charge into the voltage. The switching transistor may switch a capacitance to be coupled to the gate of the transistor AMP to change the conversion gain. It is to be noted that the switching transistor may be electrically coupled in series to the transistor RST or may be electrically coupled in parallel to the transistor RST.

[0047] The transistor TG (transfer transistor), the transistor AMP (amplification transistor), the transistor SEL (selection transistor), the transistor RST (reset transistor), and the switching transistor, which are described above, are each, for example, a MOS transistor (MOSFET) including terminals of a gate, a source, and a drain.

[0048] In the example illustrated in Fig. 3, the transistor TG, the transistor AMP, the transistor SEL, and the transistor RST are each configured by an NMOS transistor. It is to be noted that the transistor of the pixel P may also be configured by a PMOS transistor as needed.

[0049] The pixel control circuit 105 (see Fig. 1) of the imaging device 1 supplies a control signal to gates of the transistor TG, the transistor SEL, the transistor RST, the switching transistor, and the like of each of the pixels P via the above-described control line L1 to bring the transistors into an ON state (electrically-conductive state) or an OFF state (non-electrically-conductive state).

[0050] For example, the plurality of control lines L1 for the respective pixel rows of the imaging device 1 includes wiring that transmits the signal STG to control the transistor TG, wiring that transmits the signal SSEL to control the transistor SEL, wiring that transmits the signal SRST to control the transistor RST, wiring that transmits a signal to control the switching transistor, and the like.

[0051] The transistor TG, the transistor SEL, the transistor RST, the switching transistor, and the like are controlled ON / OFF by the pixel control circuit 105. The pixel control circuit 105 controls the readout circuit 15 of each of the pixels P to thereby allow the pixel signal to be outputted from each of the pixels P to the signal line L2. The pixel control circuit 105 may perform a control to read the pixel signal of each of the pixels P to the signal line L2.

[0052] Fig. 4 is a diagram illustrating another example of the circuit configuration of the pixel of the imaging device according to the embodiment. The imaging device 1 may have a configuration in which the plurality of pixels P shares one readout circuit 15. In the imaging device 1, for example, the readout circuit 15 is provided for the plurality of pixels P.

[0053] As an example, the readout circuit 15 may be arranged for every four pixels P (referred to as a pixel Pa to a pixel Pd), as illustrated in Fig. 4. The pixel Pa, the pixel Pb, the pixel Pc, and the pixel Pd share one readout circuit 15. For example, 2 × 2 pixels configured by the pixel Pa to the pixel Pd adjacent to each other share one readout circuit 15.

[0054] For example, the imaging device 1 is configured to be able to operate the readout circuit 15 time-divisionally and to read respective pixel signals of the 2 × 2 pixels. In addition, the imaging device 1 may read pixel signals to which the respective signals of the 2 × 2 pixels are added. As an example, the imaging device 1 may read a pixel signal corresponding to electric charge to which electric charge photoelectrically converted by each of the 2 × 2 pixels is added.

[0055] The photoelectric conversion section 11 (in the example illustrated in Fig. 4, the photodiode PD of the pixel Pa to the photodiode PD of the pixel Pd) may perform photoelectric conversion to generate electric charge corresponding to a received light amount. The transistors TG (in Fig. 4, the transistor TG of the pixel Pa to the transistor TG of the pixel Pd) are configured to be able to transfer electric charge photoelectrically converted by the photoelectric conversion section 11 to the floating diffusion FD.

[0056] In the example illustrated in Fig. 4, the respective transistors TG of the pixel Pa to the pixel Pd are controlled ON / OFF by signals different from each other. The transistor TG of the pixel Pa is controlled by a signal STG1, and the transistor TG of the pixel Pb is controlled by a signal STG2. In addition, the transistor TG of the pixel Pc is controlled by a signal STG3, and the transistor TG of the pixel Pd is controlled by a signal STG4.

[0057] It is to be noted that the imaging device 1 may have a configuration in which five or more pixels P, e.g., eight pixels P share one readout circuit 15. As an example, in the imaging device 1, the readout circuit 15 is arranged for every eight pixels P, and the eight pixels P share one readout circuit 15. It is to be noted that the configuration of the readout circuit 15 is not limited to the illustrated example, and is changeable as appropriate. <Configuration of Imaging Device>

[0058] Fig. 5 is a diagram illustrating an example of a cross-sectional configuration of the imaging device according to the embodiment. For example, as in the example illustrated in Fig. 5, the imaging device 1 includes a substrate 201, a substrate 202, and a substrate 203. As an example, the imaging device 1 has a configuration in which the substrate 201, the substrate 202, and the substrate 203 are stacked in the Z-axis direction.

[0059] Each of the substrate 201, the substrate 202, and the substrate 203 is configured using a semiconductor substrate such as a silicon substrate or an SOI substrate. It is to be noted that the substrate 201, the substrate 202, and the substrate 203 may be configured using an SiGe (silicon germanium) substrate or an SiC (silicon carbide) substrate, or may be configured using another material.

[0060] In the example illustrated in Fig. 5, the substrate 201 includes a layer 101 and a wiring layer 111. The substrate 202 includes a layer 102, a wiring layer 121, and a wiring layer 122. The substrate 203 includes a layer 103, a layer 104, a wiring layer 131, and a layer 132. The layer 101, the layer 102, the layer 103, and the layer 104 are each, for example, a semiconductor layer.

[0061] The layer 101, the layer 102, the layer 103, and the layer 104 are also referred to as a semiconductor layer 101, a semiconductor layer 102, a semiconductor layer 103, and a semiconductor layer 104. It is to be noted that the layer 132 of the substrate 203 is configured to have a refractive index lower than a refractive index of the semiconductor layer 103, for example. The layer 132 may be formed using a material having a refractive index lower than a refractive index of an optical waveguide (such as a waveguide 71 or a waveguide 72 described later) provided in the semiconductor layer 103.

[0062] The layer 132 may be configured by silicon oxide (SiO), or may be formed using another insulating material. As an example, the layer 132 may be configured by a BOX (Buried Oxide) layer in the SOI substrate. The layer 132 can also be referred to as an insulating layer (insulator layer) or a material layer. In addition, the layer 132 is configured by a low refractive index material, and can also be referred to as a low refractive index material layer.

[0063] It is to be noted that the layer 132 of the substrate 203 may be provided with wiring, an electrode, and the like, as needed. For example, to implement a circuit element on a side of a back surface of the semiconductor layer 103, wiring (or an electrode) may be formed that penetrates the layer 132. The layer 132 may be a layer including wiring, and can also be referred to as a wiring layer.

[0064] In the example illustrated in Fig. 5, the semiconductor layer 101, the wiring layer 111, the wiring layer 121, the semiconductor layer 102, the wiring layer 122, the wiring layer 131, the semiconductor layer 103, the layer 132, and the semiconductor layer 104 are provided, from a side on which light from a measurement target is incident. The substrate 201 including the semiconductor layer 101 is provided with, for example, the photoelectric conversion section 11, the readout circuit 15, and the like.

[0065] The semiconductor layer 101 of the substrate 201 has a surface 11S1 and a surface 11S2 opposed to each other, as illustrated in Fig. 5. The surface 11S2 is a surface on a side opposite to the surface 11S1. The surface 11S2 is, for example, a light-receiving surface (light incident surface). The semiconductor layer 102 of the substrate 202 has a surface 12S1 and a surface 12S2 opposed to each other. The surface 12S2 is a surface on a side opposite to the surface 12S1.

[0066] The semiconductor layer 103 of the substrate 203 has a surface 13S1 and a surface 13S2 opposed to each other. The surface 13S2 is a surface on a side opposite to the surface 13S1. The surface 11S1, the surface 12S1, and the surface 13S1 are each, for example, an element formation surface on which an element such as a transistor is formed. Each of the surface 11S1 and the surface 12S1 is provided with a gate electrode, a gate insulating film (e.g., a gate oxide film), or the like.

[0067] In the semiconductor layer 101, a plurality of photoelectric conversion sections 11 is provided along the surface 11S1 and the surface 11S2 of the semiconductor layer 101. The photoelectric conversion section 11 is a photoelectric conversion element, and can also be referred to as a photoelectric conversion region. For example, the plurality of photoelectric conversion sections 11 is formed to be embedded in the semiconductor layer 101. The photoelectric conversion section 11 is provided between the surface 11S1 and the surface 11S2 of the semiconductor layer 101.

[0068] For example, a lens 17 and a filter 18 are provided on a side of the surface 11S2 of the semiconductor layer 101. The lens 17 is a lens that condenses light, and is an optical member also called an on-chip lens. The lens 17 (lens section) is provided above the photoelectric conversion section 11 for each of the pixels P or for every plurality of pixels P, for example.

[0069] Light from a subject, which is a measurement target, is incident on the lens 17 via an optical system such as an imaging lens, for example. The lens 17 guides the incident light to a side of the photoelectric conversion section 11 of the pixel P. The photoelectric conversion section 11 of the pixel P photoelectrically converts light incident via the lens 17 and the filter 18. The photoelectric conversion section 11 absorbs incident light to generate electric charge.

[0070] The filter 18 is configured to selectively transmit light of a specific wavelength band of the incident light. The filter 18 is a color filter of a primary color system (RGB), a color filter of a complementary color system (CMY), a filter that transmits infrared rays, or the like. The filter 18 is provided above the photoelectric conversion section 11, for example, for each of the pixels P or for every plurality of pixels P. As an example, the filter 18 is formed between the lens 17 and the semiconductor layer 101.

[0071] The filter 18 is provided on the side of the surface 11S2 of the semiconductor layer 101, for example, for each of the pixels P or for every plurality of pixels P. In the imaging device 1, the filter 18 may be omitted as needed. The filter 18 may not be provided in some or all of the pixels P of the imaging device 1. For example, the filter 18 may not be provided in the pixel P in which white (W) light is received to perform photoelectric conversion.

[0072] In the example illustrated in Fig. 5, the lens 17 and filters 18 are stacked on the semiconductor layer 101 in a thickness direction orthogonal to the surface 11S2 of the semiconductor layer 101. The lens 17 and the filter 18 are provided on the side on which light from the optical system is incident, and the wiring layer 111 is provided on a side opposite to the light incident side. The imaging device 1 is configured as, for example, a so-called back side illumination imaging device.

[0073] For example, the transistor TG, the floating diffusion FD, and the like are provided on a side of the surface 11S1 of the semiconductor layer 101. In addition, for example, at least some of the transistors (such as the transistor AMP, the transistor SEL, and the transistor RST) of the readout circuit 15 may be provided on the side of the surface 11S1 of the semiconductor layer 101.

[0074] The wiring layer 111 is provided on the side of the surface 11S1 of the semiconductor layer 101. The wiring layer 121 is provided on a side of the surface 12S1 of the semiconductor layer 102, and the wiring layer 122 is provided on a side of the surface 12S2 of the semiconductor layer 102. In addition, the wiring layer 131 is provided on a side of the surface 13S1 of the semiconductor layer 103, and the layer 132 is provided on a side of the surface 13S2 of the semiconductor layer 103.

[0075] The wiring layers 111, 121, 122, and 131 each include, for example, a conductive film and an insulating film, and includes a plurality of wirings, a plurality of vias, and the like. Each of the wiring layers 111, 121, 122, and 131 has a configuration in which, for example, the plurality of wirings is stacked with an insulating film as an interlayer insulating film (interlayer insulating layer) being interposed therebetween. Each of the wiring layers 111, 121, 122, and 131 is configured as a multilayer wiring layer, and may include wiring of two or more layers or three or more layers.

[0076] The wiring of each of the wiring layers 111, 121, 122, and 131 may be formed using, for example, a metal material such as aluminum (Al), copper (Cu), or tungsten (W), and may be configured using polysilicon (Poly-Si) or another electrically-conductive material. The interlayer insulating film may be formed using, for example, silicon oxide (SiO), silicon nitride (SiN), silicon oxynitride (SiON), or the like, or may be configured using another insulating material. It is to be noted that the layer 132 may also be configured as a wiring layer including a plurality of wirings or the like.

[0077] In the example illustrated in Fig. 5, the wiring layer 111 includes a plurality of electrodes 91, and the wiring layer 121 includes a plurality of electrodes 92. In addition, the wiring layer 122 includes a plurality of electrodes 93, and the wiring layer 131 includes a plurality of electrodes 94. The electrode 91, the electrode 92, the electrode 93, and the electrode 94 are each an electrode formed using copper (Cu), for example.

[0078] The electrodes 91, 92, 93, and 94 are each an electrode to be used for bonding between metal electrodes, and can also be referred to as a bonding electrode. It is to be noted that the electrodes 91, 92, 93, and 94 may each be configured by a metal material other than copper, e.g., nickel (Ni), cobalt (Co), gold (Au), tin (Sn), or the like, or may be configured by another material.

[0079] As an example, the substrate 201 and the substrate 202 are attached together by bonding between metal electrodes (electrode 91 and electrode 92) including Cu, i.e., by Cu-Cu bonding. The circuit provided in the substrate 201 and the circuit provided in the substrate 202 are electrically coupled to each other via the electrode 91 and the electrode 92.

[0080] As an example, the substrate 201 and the substrate 202 are stacked to allow the surface 11S1 and the surface 12S1, on which respective elements such as transistors are formed, to be opposed to each other by the bonding between the electrodes. That is, the substrate 201 and the substrate 202 are bonded to allow a front surface of the semiconductor layer 101 and a front surface of the semiconductor layer 102 to be opposed to each other.

[0081] In addition, for example, the substrate 202 and the substrate 203 are attached together by bonding between the electrode 93 and the electrode 94, which are metal electrodes including Cu, i.e., by Cu-Cu bonding. The circuit provided in the substrate 202 and the circuit provided in the substrate 203 are electrically coupled to each other via the electrode 93 and the electrode 94.

[0082] As an example, the substrate 202 and the substrate 203 are stacked to allow the surface 12S2 and the surface 13S1 to be opposed to each other by bonding between the electrodes. That is, the substrate 202 and the substrate 203 are bonded to allow a back surface of the semiconductor layer 102 and a front surface of the semiconductor layer 103 to be opposed to each other. It is to be noted that a bump may be used to stack the substrate 201, the substrate 202, and the substrate 203.

[0083] The imaging device 1 includes a through-electrode 80, for example, as in the example illustrated in Fig. 5. The through-electrode 80 is a coupling electrode (i.e., coupling section), and couples circuits (elements) provided in different layers to each other. As an example, the through-electrode 80 is provided in the substrate 202 to penetrate the semiconductor layer 102.

[0084] In the example illustrated in Fig. 5, the through-electrode 80 extends in a thickness direction (i.e., Z-axis direction) of the substrate 202 in the semiconductor layer 102 and the wiring layer 122, and is coupled to the electrode 93. The through-electrode 80 and the electrodes 93 and 94 allow for electrical coupling between the circuit element provided in the substrate 202 and the circuit element provided in the substrate 203.

[0085] The imaging device 1 includes, for example, a plurality of through-electrodes 80, as in the example illustrated in Fig. 5 or 6, in a manner corresponding to the number of signals transmitted between the substrate 202 and the substrate 203. The through-electrode 80 is formed using, for example, a metal material such as tungsten, aluminum, or copper. It is to be noted that the through-electrode 80 may be configured by another metal material.

[0086] In the imaging device 1, for example, the readout circuit 15 and the photoelectric conversion section 11 of each of the pixels P are provided in the substrate 201. The processing circuit 200 including the AD conversion circuit 20 described above (see Fig. 1) is provided, for example, in the substrate 202 including the semiconductor layer 102. In addition, the optical circuit 300 is provided in the substrate 203. It is to be noted that the pixel control circuit 105 described above is provided in the substrate 202 or the substrate 201.

[0087] The readout circuit 15 generates a pixel signal based on electric charge converted by the photoelectric conversion section 11, and transmits the generated pixel signal to the processing circuit 200 of the substrate 202 via the signal line L2. The processing circuit 200 may perform signal processing (such as AD conversion processing) on a pixel signal of each of the pixels P, and transmit the processed pixel signal to the optical circuit 300 of the substrate 203.

[0088] The optical circuit 300 is provided, for example, in the substrate 203 including the layers 103 and 104. Each of the layer 103 and the layer 104 is, for example, a semiconductor layer, and may be a silicon layer. It is to be noted that layer 103 and the layer 104 may each be configured by another semiconductor material, or may be configured by another material.

[0089] The semiconductor layer 103 may be configured by, for example, a silicon layer (i.e., Active layer) on the BOX (Buried Oxide) layer in the SOI substrate. The optical circuit 300 is formed by utilizing, for example, a silicon photonics technology, and can also be referred to as a silicon photonics circuit. In addition, the substrate 203 in which the optical circuit 300 is formed can also be referred to as a silicon photonics substrate.

[0090] The optical circuit 300 includes, for example, a light source 30, a modulator 40, the waveguide 71, and the waveguide 72. The optical circuit 300 may include a light receiver 50. In addition, the optical circuit 300 may include an antenna, a distributor, a wavelength filter, and the like. The light source 30 is provided, for example, in the same substrate (e.g., the substrate 203) together with the modulator 40, and the like, and is mounted in the imaging device 1. It is to be noted that the light source 30 may be provided outside the imaging device 1.

[0091] The light source 30, the modulator 40, the light receiver 50, and the like are provided in the substrate 203, for example, as in the example illustrated in Fig. 5. In the example illustrated in Fig. 5, the light source 30, the modulator 40, and the light receiver 50 are provided in the semiconductor layer 103 and the wiring layer 131. It can also be said that the light source 30, the modulator 40, and the light receiver 50 are disposed on the semiconductor layer 103.

[0092] The light source 30 is configured to be able to generate and output light. The light source 30 (light source section) includes, for example, one or a plurality of light-emitting elements 31. The light-emitting element 31 may be an LD (Laser Diode) or the like, and output light to the outside. As an example, the light source 30 is electrically coupled to a circuit (e.g., the processing circuit 200) that controls the light source 30 via the electrode 93, the electrode 94, and the like.

[0093] The light source 30 includes, for example, the light-emitting element 31 which is a semiconductor laser element, and is configured to be able to output laser light as output light. As an example, the light-emitting element 31 is configured using a Group III-V compound semiconductor material (such as InP (indium phosphorus) or GaAs (gallium arsenide)), and has a configuration in which a p-type cladding layer, an active layer, and an n-type cladding layer are stacked. The light source 30 may generate laser light and emit the laser light.

[0094] The waveguide 71 is, for example, a silicon (Si) waveguide, and is provided in the semiconductor layer 103. The waveguide 71 is configured to guide inputted (incident) light. The waveguide 71 transmits light incident from the light-emitting element 31 of the light source 30, for example. The waveguide 71 is configured to convey (propagate) light to a side of the modulator 40 from a side of the light source 30.

[0095] The output light of the light source 30 is transmitted to the modulator 40 via the waveguide 71, for example. It is to be noted that the waveguide 71 may be configured by another semiconductor material. The waveguide 71 may be formed using another material having a refractive index higher than a refractive index of a peripheral member (e.g., an insulating film of the wiring layer 131, or an insulating film of the layer 132). It is to be noted that the arrangement position and the shape of the waveguide 71 are not limited to the illustrated example, and are changeable as appropriate.

[0096] The modulator 40 is configured to be able to convert an electric signal to an optical signal and output the optical signal. The modulator 40 is a modulation circuit (modulation section), and is configured to output an optical signal modulated on the basis of an inputted electric signal (e.g., pixel signal). The output light of the light source 30 is inputted to (incident on) the modulator 40 via the waveguide 71, for example. In addition, a pixel signal, which is a digital signal, is inputted to the modulator 40 from the processing circuit 200 via wiring, the through-electrode 80, and the like.

[0097] The modulator 40 is configured to modulate the light transmitted from the light source 30 on the basis of the pixel signal supplied from the processing circuit 200. For example, the modulator 40 may modulate (perform intensity modulation or phase modulation of) the light in accordance with a value of a pixel signal (pixel value), which is a digital signal, and output the modulated light, i.e., the optical signal based on the pixel signal.

[0098] For example, the modulator 40 generates, as the converted pixel signal, light (laser light) modulated in accordance with the pixel signal, which is a digital signal, i.e., the optical signal indicating a pixel value. As an example, the pixel signal of each of the pixels P transmitted from the processing circuit 200 is sequentially converted into an optical signal by the modulator 40, and is outputted (transmitted) to the outside via the waveguide 72.

[0099] The waveguide 72 is, for example, a silicon waveguide, and is provided in the semiconductor layer 103. The waveguide 72 is configured to guide inputted (incident) light. The waveguide 72 transmits light (e.g., modulated laser light) incident from the modulator 40 to the outside. It is to be noted that the waveguide 72 may be configured by another semiconductor material. The waveguide 72 may be formed using another material having a refractive index higher than a refractive index of a peripheral member (e.g., an insulating film of the wiring layer 131, or an insulating film of the layer 132).

[0100] A transmission path 75 is optically coupled to the waveguide 72, for example, as in the example schematically illustrated in Fig. 7. The transmission path 75 is an optical transmission path, and is configured by an optical fiber, for example. As an example, the transmission path 75 includes a core part and a cladding part that have refractive indexes different from each other. It is to be noted that the transmission path 75 may include one or a plurality of cores and one or a plurality of clads.

[0101] The modulated optical signal is inputted to the transmission path 75 from the modulator 40 of the optical circuit 300. The optical signal outputted from the modulator 40 is transmitted (propagated) to an external device (e.g., an image processor, etc.), for example, via the waveguide 72 and the transmission path 75 coupled to the waveguide 72. It is to be noted that communication of the optical signal between the optical circuit 300 of the imaging device 1 and the external device may be performed wirelessly.

[0102] The light receiver 50 is configured to be able to receive an optical signal (receive light). The light receiver 50 is a light-receiving circuit, and includes one or a plurality of light-receiving elements 51. The light-receiving element 51 is, for example, a photodiode (PD), and is configured to be able to receive an optical signal. The light-receiving element 51 may be configured by a germanium photodiode (GePD). As an example, the light-receiving element 51 is provided on the surface 13S1 of the semiconductor layer 103.

[0103] The light receiver 50 is configured to receive an optical signal and convert the optical signal into an electric signal. The light receiver 50 is configured to receive the optical signal via the transmission path 75 illustrated in Fig. 7 or another transmission path. The light-receiving element 51 may receive light, generate electric charge by photoelectric conversion, and generate a current. The light-receiving element 51 outputs a signal based on the received optical signal.

[0104] In the imaging device 1, for example, a signal corresponding to a photocurrent flowing through the light-receiving element 51 is generated in response to reception of optical signals from the external device, and the generated signal is outputted to an amplification circuit (unillustrated). For example, the amplification circuit is electrically coupled to the light receiver 50, and is configured to be able to output a signal based on a photocurrent generated by the light receiver 50.

[0105] The amplification circuit is configured using, for example, a transimpedance amplifier (TIA: Transimpedance Amplifier). The amplification circuit may convert a current signal detected by the light receiver 50 into a voltage signal, and output the voltage signal to the processing circuit 200. The optical circuit 300 may include an amplification circuit (e.g., TIA circuit). It is to be noted that the light receiver 50 and the amplification circuit can also be referred to collectively as a light-receiving circuit or a detection circuit.

[0106] For example, the processing circuit 200 performs AD conversion processing on a signal inputted from the amplification circuit. The processing circuit 200 is able to receive a signal from an external device (external circuit) via the light receiver 50, the amplification circuit, or the like, and obtain a signal related to a control of the imaging device 1 (e.g., a signal instructing an operation mode, a signal instructing an imaging condition, etc.), for example. The imaging device 1 may transmit and receive the optical signal via one or a plurality of transmission paths 75, for example.

[0107] Fig. 8 is an explanatory diagram of a layout example of the imaging device according to the embodiment. (A) of Fig. 8 illustrates a layout example of the imaging device 1 in the substrate 201. (B) of Fig. 8 illustrates a layout example of the imaging device 1 in the substrate 202. In addition, (C) of Fig. 8 illustrates a layout example of the imaging device 1 in the substrate 203.

[0108] As illustrated in (A) of Fig. 8, the substrate 201 is provided with, for example, the pixel section 100 (i.e., a pixel array). In the substrate 201, as an example, the plurality of pixels P each including the photoelectric conversion section 11 is arranged to align in the X-axis direction and the Y-axis direction. The substrate 202 is provided with the processing circuit 200, for example, as in the example illustrated in (B) of Fig. 8.

[0109] The substrate 203 is provided with the optical circuit 300, for example, as in the example illustrated in (C) of Fig. 8. In addition, the substrate 202 and the substrate 203 are provided with an electrode region 85. The electrode region 85 is a region provided with the through-electrode 80 described above. The electrode region 85 is provided with the plurality of through-electrodes 80 in a manner corresponding to the number of signals to be transmitted. In the substrate 202, for example, the electrode region 85 including the plurality of through-electrodes 80 is provided in a peripheral region of the processing circuit 200.

[0110] As in the example illustrated in (B) of Fig. 8, the electrode region 85 is provided at an end (side part) of the processing circuit 200, for example. As an example, the electrode region 85 includes the plurality of through-electrodes 80 arranged to align in the Y-axis direction in a plan view (e.g., in a case of being viewed on an XY plane). In the substrate 203, for example, the electrode region 85 is provided in a peripheral region of the optical circuit 300. For example, as in the example illustrated in (C) of Fig. 8, the electrode region 85 is provided at an end (side part) of the optical circuit 300.

[0111] The plurality of through-electrodes 80 provided in the imaging device 1 includes, for example, the through-electrode 80 that transmits a pixel signal from the processing circuit 200, the through-electrode 80 that transmits a signal to control the optical circuit 300 (modulator 40, light receiver 50, etc.), the through-electrode 80 that transmits signals from the light receiver 50 and the amplification circuit (e.g., TIA circuit), and the like.

[0112] The optical circuit 300 of the imaging device 1 may include an optical multiplexer / demultiplexer, a switch, a distributor, a wavelength filter, and the like. The optical circuit 300 may include, for example, an AWG (Arrayed Waveguide Grating) as the optical multiplexer / demultiplexer, and may be configured to enable wavelength division multiplex (WDM: Wavelength Division Multiplex) communication.

[0113] The optical circuit 300 may include, for example, a plurality of switches (optical switches), and may be configured to be able to select (switch) a transmission path (waveguide) which is a transmission destination of the optical signal. The optical circuit 300 may be configured to broadcast signals to a plurality of external chips (e.g., a plurality of APs (Application Processors) simultaneously.

[0114] Fig. 9 is an explanatory diagram of a configuration example of the optical circuit of the imaging device according to the embodiment. The optical circuit 300 includes a plurality of modulators 40 and a distributor 41. As an example, the modulator 40 is configured by a wavelength selective modulator (e.g., a ring modulator). It is to be noted that the light source 30 may be provided in the imaging device 1, or may be provided outside the imaging device 1. Fig. 9 schematically illustrates an example of a case where the light source 30 is provided as an external light source.

[0115] In the example illustrated in Fig. 9, the output light of the light source 30 as the external light source is inputted to the distributor 41 via the transmission path 75. The light from the light source 30 is distributed to two lanes by the distributor 41, and is modulated in each of the plurality of modulators 40 (four modulators 40 in Fig. 9) for each of the lanes depending on the pixel signal of each of the pixels P, for example. The optical circuit 300 may output the optical signal modulated by each of the modulators 40 to the outside via the transmission path 75.

[0116] The transmission path 75 may include, for example, a plurality of optical fibers (such as an optical fiber between the external light source and the optical circuit 300, an optical fiber between the optical circuit 300 and the external device, and the like), and may be configured as a transmission path group. It can also be said that the transmission path 75 that transmits the output light of the light source 30 as the external light source to the optical circuit 300, the transmission path 75 that transmits the optical signal modulated by the optical circuit 300 to the external device, and the like are arranged.

[0117] Fig. 10 is an explanatory diagram of another configuration example of the optical circuit of the imaging device according to the embodiment. The optical circuit 300 includes the plurality of modulators 40, a demultiplexer 42, and a multiplexer 43. The modulator 40 is configured using, for example, a Mach-Zehnder interferometer (Mach-Zehnder Interferometer). It is to be noted that Fig. 10 schematically illustrates an example of a case where the light source 30 is provided as the external light source.

[0118] In the example illustrated in Fig. 10, the output light of the light source 30 as the external light source is inputted to the demultiplexer 42 via the transmission path 75. The light from the light source 30 is separated (branched), i.e., wavelength-separated into three lanes by the demultiplexer 42, and is modulated in the respective three modulators 40 depending on the pixel signal of each of the pixels P, for example. The optical signal modulated by each of the modulators 40 is multiplexed (combined), i.e., wavelength-multiplexed by the multiplexer 43, and is outputted to the outside via the transmission path 75.

[0119] As in the example illustrated in (C) of Fig. 8, the substrate 203 is provided with, for example, the modulator 40, the light receiver 50, a circuit region 86, a circuit region 87, and the light source 30. The circuit region 86 is provided with, for example, the distributor 41, the demultiplexer 42, the multiplexer 43, the switch, the wavelength filter, and the like, which are described above. In addition, the circuit region 87 is provided with, for example, a plurality of waveguides (i.e., waveguide wiring) such as the waveguide 71 and the waveguide 72.

[0120] In addition, as illustrated in (C) of Fig. 8, the optical circuit 300 may include a spot size converter 74 (SSC: Spot Size Converter). For example, as in the example illustrated in (C) of Fig. 8, the spot size converter 74 is provided between the circuit region 87 including the waveguides 71 and 72 and the transmission path 75 (optical fiber) in the substrate 203.

[0121] As in the example illustrated in (B) of Fig. 8, the processing circuit 200 may include an I / F (interface) circuit 25. The I / F circuit 25 is configured, for example, to control driving of the modulator 40, the light receiver 50, and the like. The I / F circuit 25 can also be referred to as an I / F drive circuit (or an optical I / F circuit). The I / F circuit 25 is configured to output a pixel signal of each of the pixels P after the signal processing to the modulator 40 of the substrate 203 via the through-electrode 80 in the electrode region 85.

[0122] As in the example illustrated in (B) of Fig. 8 and (C) of Fig. 8, the modulator 40 and the light receiver 50 are arranged in the substrate 203, for example, to be positioned immediately below the I / F circuit 25 of the substrate 202. In this case, it is possible to minimize a wiring distance between the I / F circuit 25 and the modulator 40 (or the light receiver 50). The I / F circuit 25 may be provided to overlap at least a portion of the modulator 40 or the light receiver 50 when viewed from above the substrate 202.

[0123] Configuring the imaging device 1 as described above enables the I / F circuit 25, the through-electrode 80 of the electrode region 85, and the like to efficiently perform signal transmission between the processing circuit 200 and the optical circuit 300. It is possible to suppress signal delay or signal attenuation in the transmission path between the processing circuit 200 and the optical circuit 300 as an optical communication circuit. It is to be noted that one of the modulator 40 or the light receiver 50, e.g., only the modulator 40 may be disposed immediately below the I / F circuit 25.

[0124] In the imaging device 1, as in the example illustrated in Fig. 11 or 12, the modulator 40 may be disposed to allow a long side of the modulator 40 to intersect (e.g., to be orthogonal to) the alignment direction of the through-electrode 80 (i.e., the Y-axis direction). For example, it is possible to input, from an end (e.g., a left end) of the modulator 40 (e.g., Mach-Zehnder interferometer), the pixel signal transmitted via the through-electrode 80, thus making it possible to suppress a decrease in modulation accuracy.

[0125] Fig. 13 is an explanatory diagram of another layout example of the imaging device according to the embodiment. (A) of Fig. 13 illustrates a layout example of the imaging device 1 in the substrate 201. (B) of Fig. 13 illustrates a layout example of the imaging device 1 in the substrate 202. In addition, (C) of Fig. 13 illustrates a layout example of the imaging device 1 in the substrate 203.

[0126] The processing circuit 200 of the imaging device 1 may be provided separately in the substrate 202 and the substrate 203. It is possible to increase an area of a region where the processing circuit 200 is disposed. For example, as in the example illustrated in (B) of Fig. 13 and (C) of Fig. 13, a portion of the processing circuit 200 is provided in the substrate 202, and another portion of the processing circuit 200 is provided in the substrate 203. It is possible to increase an area of the processing circuit 200.

[0127] The imaging device 1 according to the present embodiment includes the optical circuit 300 as described above. It is therefore possible to perform communication utilizing an optical signal, thus making it possible to efficiently perform signal transmission. It becomes possible for the imaging device 1 to communicate with the outside using an optical signal, thus making it possible to efficiently perform signal transmission from the imaging device 1 to the outside. It becomes possible for the imaging device 1, for example, to transmit, to the outside at a high speed, a pixel signal of each of the pixels P having been signal-processed by the processing circuit 200.

[0128] As described above, the imaging device 1 includes a structure configured by stacking the plurality of substrates. The optical circuit 300 is provided to be stacked on the substrate in which the processing circuit 200 is disposed. It is therefore possible to reduce a wiring distance between the processing circuit 200 and the optical circuit 300, thus making it possible to suppress an increase in power consumption and signal delay caused by a parasitic capacitance. In addition, for example, it is possible to execute integration of optical communication elements can be performed while avoiding an increase in a packaging area.

[0129] In addition, according to the photodetector (imaging device 1) according to the present disclosure, it is possible to adopt communication utilizing an optical signal also in a case of communication in a package at the time of chiplet integration or in a case of communication in a chip, thus making it possible to efficiently perform signal transmission. In addition, in a case where the pixel section 100, the processing circuit 200, and the optical circuit 300 are disposed separately in the plurality of substrates as in the case of the above-described example, it becomes possible to optimize processes for each of the substrates.

[0130] Figs. 14 and 15 are each an explanatory diagram of a configuration example of a photodetection system according to the embodiment. A photodetection system 10 includes, for example, the imaging device 1, which is an example of the photodetector, and one or a plurality of external devices 2. As an example, the external device 2 is a semiconductor chip, and may be an AP (Application Processor).

[0131] As an example, the external device 2 includes a processor and a memory (such as a ROM or a RAM), and is configured to be able to execute various types of signal processing. The external device 2 is configured by, for example, a GPU (Graphics Processing Unit), a CPU (Central Processing Unit), a memory (such as ROM or RAM), and the like. The photodetection system 10 may include the plurality of external devices 2 (an external device 2a to an external device 2c in Fig. 15).

[0132] The external device 2 includes an optical circuit 310, as illustrated in Fig. 14 or 15. The optical circuit 310 includes, for example, a light receiver (light-receiving circuit), and is configured to be able to receive an optical signal. In addition, for example, the optical circuit 310 includes a modulator (modulation circuit), and is configured to be able to convert an electric signal into an optical signal and output the converted optical signal. The optical circuit 310 may include circuits (such as a light receiver or a modulator) similar to those of the optical circuit 300 of the imaging device 1 described above.

[0133] As an example, the plurality of transmission paths 75 (a transmission path 75a to a transmission path 75c in Fig. 15) is coupled to the imaging device 1. In the example illustrated in Fig. 15, the imaging device 1 is coupled to the external device 2a including the GPU, the external device 2b including the memory, and the external device 2b including the CPU, by the transmission path 75a, the transmission path 75b, and the transmission path 75c (e.g., optical fibers).

[0134] The processing circuit 200 of the imaging device 1 and a circuit (GPU, memory, or CPU) of the external device 2 transmit and receive signals via the optical circuit 300 and the optical circuit 310, for example. In the example illustrated in Fig. 15, the optical circuit 300 of the imaging device 1 performs communication of optical signals with the optical circuit 310 of the external device 2a via the transmission path 75a. In addition, the optical circuit 300 performs communication of optical signals with the optical circuit 310 of the external device 2b via the transmission path 75b, and performs communication of optical signals with the optical circuit 310 of the external device 2c via the transmission path 75c.

[0135] The photodetection system 10 is able to transmit and receive optical signals by using the imaging device 1 and the external device 2 each including the optical circuit as the optical I / F, thus making it possible to efficiently perform signal transmission. For example, it becomes possible to efficiently perform real-time processing of large-volume information. In addition, it becomes possible to prevent an increase in power consumption in a case where the speed of signal transmission becomes higher or the distance of signal transmission becomes longer.

[0136] It becomes possible, in the photodetection system 10 according to the present embodiment, to perform appropriate communication even in a case where the distance between the imaging device 1 and the external device 2 (e.g., AP) is long and where data of high resolution and high frame rate is transferred (e.g., in a case of automated driving). It becomes possible to achieve a photodetector and a photodetection system that enable suitable communication.

[0137] Figs. 16 and 17 are each an explanatory diagram of another configuration example of the photodetection system according to the embodiment. The photodetection system 10 may be configured to be able to execute communication using an optical signal and communication using an electric signal between the imaging device 1 and the external device 2. For example, the imaging device 1 and the external device 2 are configured to transmit and receive optical signals via the transmission path 75 (optical fiber) and to transmit and receive electric signals via a transmission path 76 (e.g., electric wire).

[0138] The plurality of transmission paths 75 (transmission path 75a to transmission path 75c in Fig. 17) and a plurality of the transmission paths 76 (a transmission path 76a to a transmission path 76c in Fig. 17) may be coupled to the imaging device 1. Each of the transmission paths 76 is configured by, for example, an electric signal cable corresponding to communication of electric signals. The imaging device 1 performs communication by optical signals with the external device 2a via the transmission path 75a, and performs communication by electric signals with the external device 2a via the transmission path 76a.

[0139] In addition, in the example illustrated in Fig. 17, the imaging device 1 performs communication by optical signals with the external device 2b via the transmission path 75b, and performs communication by electric signals with the external device 2b via the transmission path 76b. Further, the imaging device 1 performs communication by optical signals with the external device 2c via the transmission path 75c, and performs communication by electric signals with the external device 2c via the transmission path 76c.

[0140] As an example, the photodetection system 10 may use an optical signal to transmit a pixel signal from the imaging device 1 to the external device 2, and may use an electric signal to transmit a signal (e.g., control signal) from the external device 2 to the imaging device 1. Examples of the control signal transmitted from the external device 2 to the imaging device 1 include a control signal related to an operation mode, a control signal related to an imaging condition, or another control signal.

[0141] The optical circuit 300 of the imaging device 1 may include only the modulator 40 among the modulator 40 and the light receiver 50 described above. In addition, the optical circuit 310 of the external device 2 may include only the light receiver 50 among the modulator 40 and the light receiver 50 described above. It is possible to reduce circuit areas of the optical circuits 300 and 310 and reduce the power consumption. It is to be noted that the imaging device 1 and the external device 2 may be configured to transmit and receive optical signals by wireless communication.

[0142] Figs. 18A to 18H are each a diagram illustrating an example of a method of manufacturing the imaging device according to the embodiment. As illustrated in Fig. 18A, elements such as transistors and the photoelectric conversion sections 11 of the respective pixels P are formed in the semiconductor layer 101. In addition, the wiring layer 111 including the electrodes 91, wiring, and the like is formed on the surface 11S1 of the semiconductor layer 101.

[0143] In addition, as illustrated in Fig. 18B, the transistors and the like of the processing circuit 200 are formed in the semiconductor layer 102, and the wiring layer 121 including the electrodes 92, wiring, and the like is formed on the surface 12S1 of the semiconductor layer 102. Then, the semiconductor layer 101 provided with the wiring layer 111 and the semiconductor layer 102 provided with the wiring layer 121 are opposed to each other to allow the substrate 201 and the substrate 202 to be bonded together, as illustrated in Fig. 18C. Then, the thickness of the semiconductor layer 102 is decreased (thinned).

[0144] Next, as illustrated in Fig. 18D, the wiring layer 122 is formed on the surface 12S2 of the semiconductor layer 102, and the through-electrode 80, the electrodes 93, and the like are formed therein. In addition, the substrate 203 including the semiconductor layer 103 is prepared. Then, as illustrated in Fig. 18E, the elements of the optical circuit 300, e.g., the light source 30, the modulator 40, the light receiver 50, and the like are formed on the side of the surface 13S1 of the semiconductor layer 103.

[0145] In addition, as illustrated in Fig. 18E, the wiring layer 131 including the electrode 94, wiring, and the like is formed on the surface 13S1 of the semiconductor layer 103. Then, the semiconductor layer 102 provided with the wiring layer 122 and the semiconductor layer 103 provided with the wiring layer 131 are opposed to each other to allow the substrate 202 and the substrate 203 to be bonded together, as illustrated in Fig. 18F. Thereafter the thickness of the semiconductor layer 101 is decreased.

[0146] Next, as illustrated in Fig. 18G, the filter 18, the lens 17, and the like are formed on the side of the surface 11S2 of the semiconductor layer 101. Thereafter, singulation (i.e., chip separation), mounting of the transmission path 75 (optical fiber) as illustrated in Fig. 18H, and the like are performed. The manufacturing method as described above enables the imaging device 1 illustrated in any of Figs. 5 to 7 or the like to be manufactured. It is to be noted that the above-described method of manufacturing the imaging device is merely exemplary, and another manufacturing method may also be adopted. <Workings and Effects>

[0147] The photodetector according to the present embodiment includes: a first substrate (e.g., substrate 201) including a photoelectric conversion element that photoelectrically converts light; a second substrate (e.g., substrate 202) including at least a portion of a processing circuit (processing circuit 200) that is able to execute signal processing of a first signal (e.g., pixel signal) generated on the basis of electric charge converted by the photoelectric conversion element, the second substrate being stacked on the first substrate; and an optical circuit (optical circuit 300) that is able to output a first optical signal based on the first signal.

[0148] The photodetector (imaging device 1) according to the present embodiment includes the substrate 201 including the photoelectric conversion section 11, the substrate 202 including at least a portion of the processing circuit 200, and the optical circuit 300 that is able to output an optical signal based on a pixel signal. It is therefore possible for the imaging device 1 to perform communication utilizing the optical signal. It becomes possible to achieve a photodetector that enables suitable communication.

[0149] Next, description is given of modification examples of the present disclosure. Hereinafter, components similar to those of the foregoing embodiment are denoted by the same reference numerals, and descriptions thereof are omitted as appropriate. <2. Modification Examples> (2-1. Modification Example 1)

[0150] Fig. 19 is an explanatory diagram of a configuration example of an imaging device according to Modification Example 1 of the present disclosure. As in the example illustrated in Fig. 19, the imaging device 1 may include a light-blocking member 60. The light-blocking member 60 is a light-blocking section (light-blocking film) configured by a member that blocks light. As in the example illustrated in Fig. 19, the light-blocking member 60 is provided above the optical circuit 300 to suppress incidence of unnecessary light on each element of the optical circuit 300.

[0151] The light-blocking member 60 is provided, for example, above the optical circuit 300, to cover the optical circuit 300. In the example illustrated in Fig. 19, the light-blocking member 60 is formed in the substrate 203, and is positioned between the optical circuit 300 and the substrate 202 provided with the processing circuit 200. The light-blocking member 60 may be formed to cover all or a portion of the optical circuit 300 in a plan view (i.e., in a case of being viewed on the XY plane).

[0152] For example, the light-blocking member 60 is provided to cover the modulator 40 of the optical circuit 300. In addition, for example, the light-blocking member 60 may be provided to cover the light source 30 including the light-emitting element 31, and the light receiver 50 including the light-receiving element 51. It is to be noted that the light-blocking member 60 may be disposed to cover only a portion of the optical circuit 300 (e.g., any one or two of the modulator 40, the light receiver 50, or the light source 30).

[0153] The light-blocking member 60 may be configured by wiring of the wiring layer 131, for example. The light-blocking member 60 is configured by, for example, aluminum (Al), tungsten (W), or the like. It is to be noted that the light-blocking member 60 may be configured by another metal material that blocks light, e.g., copper (Cu) or the like. The light-blocking member 60 may be configured using a metal compound. The light-blocking member 60 may be configured by a material that absorbs light.

[0154] In the imaging device 1, providing the light-blocking member 60 makes it possible to suppress incidence of unnecessary light, as schematically indicated by broken line arrows A1 in Fig. 20, on the modulator 40, the light receiver 50, and the like of the optical circuit 300. It is possible to prevent external light from adversely affecting the optical circuit 300. For example, it is possible to suppress passing of light from a subject, which is measurement target, through the substrate 201 or the like and incidence of the light on the modulator 40, thus making it possible to suppress mixture of noise into a pixel signal. It becomes possible to prevent a decrease in quality of the pixel signal.

[0155] Fig. 21 is an explanatory diagram of another configuration example of the imaging device according to Modification Example 1. As in the example illustrated in Fig. 21, the light-blocking member 60 may be provided in a plurality of layers. In the example illustrated in Fig. 21, the light-blocking member 60 is provided in each of two layers of the wiring layer 131. The light-blocking member 60 may be formed in a plurality of layers, and may have an alternate structure. It is possible to achieve a high light-blocking effect while securing a gap for wiring.

[0156] In the imaging device 1 according to the present modification example, providing the light-blocking member 60 makes it possible to suppress incidence of unnecessary light on the light source 30, the modulator 40, the light receiver 50, the amplification circuit (TIA circuit), or the like, and to suppress, for example, a decrease in characteristics of the optical circuit 300 (a decrease in modulation accuracy, a decrease in accuracy of conversion into a digital signal, etc.). (2-2. Modification Example 2)

[0157] Fig. 22 is an explanatory diagram of a configuration example of an imaging device according to Modification Example 2. In addition, Fig. 23 is an explanatory diagram of a layout example of the imaging device according to Modification Example 2. (A) of Fig. 23 illustrates a layout example of the imaging device 1 in the substrate 201. In addition, (B) of Fig. 23 illustrates a layout example of the imaging device 1 in the substrate 202, and (C) of Fig. 23 illustrates a layout example of the imaging device 1 in the substrate 203.

[0158] In the imaging device 1, the through-electrode 80 may be provided in a region of the substrate 202 corresponding to the pixel section 100 (pixel array), i.e., in a region below the photoelectric conversion section 11 of each of the pixels P. The through-electrode 80 may be provided for each pixel unit or for every plurality of pixel units (i.e., for every predetermined number of pixels). For example, the imaging device 1 includes the plurality of through-electrodes 80 (a through-electrode 80A and a through-electrode 80B in the example illustrated in Fig. 22) in a manner corresponding to the number of pixels (or the number of pixel signals).

[0159] In the example illustrated in Fig. 22, the imaging device 1 includes the through-electrode 80A provided in the substrate 202 to be positioned in the pixel section 100 and the through-electrode 80B provided in the substrate 202 to be positioned outside the pixel section 100. The through-electrode 80A is configured, for example, as a nano TSV, and has a width that is smaller (narrower) than a width of the through-electrode 80B in the X-axis direction (or the Y-axis direction). The through-electrode 80A may be provided for each of the pixels P or for every plurality of pixels P, for example.

[0160] As in the example schematically illustrated in (C) of Fig. 23, the plurality of modulators 40 and a plurality of light receivers 50 may be provided across the entire surface of the substrate 203, i.e., in the entirety of the substrate 203. In the substrate 203, for example, the modulators 40 (or the light receivers 50) of the number corresponding to the number of signals transmitted between the processing circuit 200 and the optical circuit 300 may be disposed. Configuring the imaging device 1 as described above makes it possible to efficiently perform signal transmission between the substrate 202 and the substrate 203. The through-electrode 80 is also disposed in the pixel section 100, thus enabling a flexible layout (e.g., wiring layout). (2-3. Modification Example 3)

[0161] Fig. 24 is an explanatory diagram of a configuration example of an imaging device according to Modification Example 3. Instead of or in addition to the through-electrode 80, wiring 81 may be provided, as in the example illustrated in Fig. 24. The wiring 81 is provided, for example, to reach an element such as a transistor formed on an element formation surface of a substrate, from a side of a surface opposite to the element formation surface of the substrate. The wiring 81 can also be referred to as back surface wiring.

[0162] The imaging device 1 includes a plurality of wirings 81 in a manner corresponding to the numbers of signals transmitted between the substrate 202 and the substrate 203, for example, as in the example illustrated in Fig. 24. The wiring 81 is provided, for example, by digging the semiconductor layer 102. In the example illustrated in Fig. 24, the wiring 81 is formed from the side of the surface 12S2 to the side of the surface 12S1 of the substrate 202, and is electrically coupled to a terminal (e.g., a drain or a source) of the transistor on the side of the surface 12S1.

[0163] In the imaging device 1 according to the present modification example, the wiring 81 (i.e., back surface wiring) enables coupling between the circuits, thus making it possible to suppress generation of an unnecessary parasitic capacitance (e.g., wiring capacitance) in the imaging device 1. It is to be noted that the number and arrangement of the wiring 81 are not limited to the illustrated example, and are changeable as appropriate. (2-4. Modification Example 4)

[0164] The description has been given, in the foregoing embodiment and modification examples, of the configuration example of the imaging device 1, which however is merely exemplary; the configuration of the imaging device 1 is not limited to the above-described example. Fig. 25 is an explanatory diagram of a configuration example of an imaging device according to Modification Example 4. The imaging device 1 may have a stacked structure as in the example illustrated in Fig. 25.

[0165] In the example illustrated in Fig. 25, the wiring layer 122 includes the plurality of electrodes 92, and the wiring layer 121 includes the plurality of electrodes 93. The substrate 201 and the substrate 202 are stacked to allow the surface 11S1 and the surface 12S2 to be opposed to each other by bonding between the electrodes (electrodes 91 and 92), for example. That is, the substrate 201 and the substrate 202 are bonded to allow the front surface of the semiconductor layer 101 and the back surface of the semiconductor layer 102 be opposed to each other.

[0166] In addition, the substrate 202 and the substrate 203 are stacked to allow the surface 12S1 and the surface 13S1 to be opposed to each other by bonding between the electrodes (electrodes 93 and 94). That is, the substrate 202 and the substrate 203 are bonded to allow a front surface of the substrate 202 and a front surface of the substrate 203 to face each other. It is possible, in the imaging device 1 according to the present modification example, to reduce a parasitic capacitance (wiring capacitance) to be added to the wiring between the substrate 202 and the substrate 203. For example, it is possible to reduce signal delay in the processing circuit 200 and the optical circuit 300, thus making it possible to reduce the power consumption.

[0167] It is to be noted that the imaging device 1 may be provided with the above-described wiring 81 (i.e., back surface wiring). In the case of the example illustrated in Fig. 25, instead of or in addition to the through-electrode 80, the wiring 81 is provided in the substrate 202. For example, the wiring 81 is formed by digging the semiconductor layer 102. As an example, the wiring 81 is formed from the side of the surface 12S2 to the side of the surface 12S1 of the substrate 202, and is electrically coupled to the terminal (e.g., a drain or a source) of the transistor on the side of the surface 12S1. (2-5. Modification Example 5)

[0168] Figs. 26 and 27 are each an explanatory diagram of a configuration example of an imaging device according to Modification Example 5. Fig. 27 schematically illustrates an implementation example of the transmission path 75. Fig. 28 is an explanatory diagram of a layout example of the imaging device. (A) of Fig. 28 illustrates a layout example of the imaging device 1 in the substrate 201. In addition, (B) of Fig. 28 illustrates a layout example of the imaging device 1 in the substrate 203, and (C) of Fig. 28 illustrates a layout example of the imaging device 1 in the substrate 202.

[0169] In the examples illustrated in Figs. 26 to 28, the substrate 201, the substrate 203, and the substrate 202 are provided from a side on which light from a measurement target is incident. The substrate 203 is disposed between the substrate 201 and the substrate 202. The substrate 203 includes, for example, the semiconductor layer 103, the wiring layer 131, and the layer 132.

[0170] In the examples illustrated in Figs. 26 and 27, the layer 132 includes the plurality of electrodes 92, and the wiring layer 131 includes the plurality of electrodes 93. In addition, the wiring layer 121 includes the plurality of electrodes 94. The substrate 201 and the substrate 203 are stacked to allow the surface 11S1 and the surface 13S2 to be opposed to each other, for example, by bonding between the electrodes (electrodes 91 and 92). That is, the substrate 201 and the substrate 203 are bonded to allow the front surface of the semiconductor layer 101 and the back surface of the semiconductor layer 103 be opposed to each other.

[0171] In addition, the substrate 203 and the substrate 202 are stacked to allow the surface 13S1 and the surface 12S1 to be opposed to each other by the bonding between the electrodes (electrodes 93 and 94). That is, the substrate 203 and the substrate 202 are bonded to allow the front surface of the substrate 203 and the front surface of the substrate 202 to face each other.

[0172] In addition, in the example illustrated in Fig. 26 or the like, the through-electrode 80 is provided in the substrate 203. The through-electrode 80 is provided in the substrate 203 to penetrate the semiconductor layer 103. In the example illustrated in Fig. 26 or the like, for example, the circuit element provided in the substrate 201 and the circuit element provided in the substrate 202 are electrically coupled to each other via the through-electrode 80, the electrodes 91 to 94, and the like.

[0173] The above-described signal line L2 (see Figs. 1, 3, or the like) that transmits a pixel signal is a signal line that uses the through-electrode 80, for example. In the substrate 203, for example, the through-electrode 80 is provided for each of the signal lines L2. As an example, the pixel signal of the pixel P of the pixel section 100 is transmitted to the processing circuit 200 including the AD conversion circuit 20 provided in the substrate 202 via the electrodes 91 and 92, the through-electrode 80, which is a portion of the signal line L2, and the electrodes 93 and 94.

[0174] As in the example illustrated in (B) of Fig. 28 and (C) of Fig. 28, the modulator 40 and the light receiver 50 may be disposed in the substrate 203 to be positioned immediately above the I / F circuit 25 of the substrate 202, for example. In this case, it is possible to minimize the wiring distance between the I / F circuit 25 and the modulator 40 (or the light receiver 50). The modulator 40 (or the light receiver 50) may be provided to overlap at least a portion of the I / F circuit 25.

[0175] For example, as in the example illustrated in (B) of Fig. 28, the electrode region 85 includes the plurality of through-electrodes 80 arranged to align in the X-axis direction. As an example, the electrode region 85 is provided in a peripheral region of the optical circuit 300. In the example illustrated in (B) of Fig. 28, the electrode region 85 is provided to follow an edge (edge part) of the substrate 203.

[0176] It is to be noted that, the through-electrode 80 may be provided in a region of the optical circuit 300 of the substrate 203, as in the example illustrated in Fig. 26 or 27. In this case, for example, arranging the through-electrode 80 while avoiding a region of the semiconductor layer 103 with an island shape makes it possible to reduce a parasitic capacitance to be added to the through-electrode 80.

[0177] Configuring the imaging device 1 as in the examples illustrated in Figs. 26 to 28 makes it possible to increase an area of a region in which the processing circuit 200 is disposed. It can be expected to reduce a parasitic capacitance, as compared with the case where the through-electrode 80 is provided in substrate provided with the processing circuit 200. In addition, it is possible to facilitate the arrangement of the through-electrode 80 across the entire area of the substrate.

[0178] In addition, the substrate 203 and the substrate 202 are stacked to allow the front surface of the substrate 203 and the front surface of the substrate 202 to face each other. This makes it possible to suppress generation of a large parasitic capacitance between the substrate 202 and the substrate 203, thus making it possible to prevent an increase in power consumption and signal delay.

[0179] It is to be noted that a portion of the processing circuit 200 may be disposed in the substrate 203. In addition, the imaging device 1 may include the light-blocking member 60 described above. For example, the light-blocking member 60 (light-blocking film) is provided in the layer 132 of the substrate 203, and is positioned between the substrate 201 and the optical circuit 300. The light-blocking member 60 may be formed in the layer 132 to cover a portion or all of the optical circuit 300 in a plan view (i.e., in a case of being viewed on the XY plane).

[0180] Figs. 29 and 30 are each an explanatory diagram of another configuration example of the imaging device according to Modification Example 5. Fig. 30 schematically illustrates an implementation example of the transmission path 75. In the examples illustrated in Figs. 29 and 30, the wiring layer 131 includes the plurality of electrodes 92, and the layer 132 include the plurality of electrodes 93.

[0181] The substrate 201 and the substrate 203 are stacked to allow the surface 11S1 and the surface 13S1 to be opposed to each other, for example, by bonding between the electrodes (electrodes 91 and 92). That is, the substrate 201 and the substrate 203 are bonded to allow the front surface of the semiconductor layer 101 and the front surface of the semiconductor layer 103 to be opposed to each other.

[0182] In addition, the substrate 203 and the substrate 202 are stacked to allow the surface 13S2 and the surface 12S1 to be opposed to each other, for example, by bonding between the electrodes (electrodes 93 and 94). That is, the substrate 203 and the substrate 202 are bonded to allow a back surface of the substrate 203 and the front surface of the substrate 202 to face each other.

[0183] In the example illustrated in Fig. 29 or 30, the substrate 201 and the substrate 203 are stacked to allow a front surface of the substrate 201 and the front surface of the substrate 203 to face each other. In this case, a plurality of substrates 202 (e.g., a substrate 202a and a substrate 202b) may be provided to be stacked on the side of the surface 13S2 of the substrate 203. The processing circuit 200 may be provided separately in the substrate 202a and the substrate 202b. For example, each of the substrates 202a and 202b is configured as a semiconductor chip, and is mounted on the imaging device 1.

[0184] It is to be noted that, also in the case of the example illustrated in Fig. 29 or 30, a portion of the processing circuit 200 may be disposed in the substrate 203. In addition, the imaging device 1 may be provided with the light-blocking member 60. In the case of the example illustrated in Fig. 29 or the like, for example, the light-blocking member 60 is provided in the wiring layer 131 of the substrate 203, and is positioned between the substrate 201 and the optical circuit 300. The light-blocking member 60 may be formed in the wiring layer 131 to cover a portion or all of the optical circuit 300 in a plan view. (2-6. Modification Example 6)

[0185] Figs. 31 and 32 are each an explanatory diagram of a configuration example of an imaging device according to Modification Example 6. Fig. 32 schematically illustrates an implementation example of the transmission path 75. The substrate 201 may have, for example, a structure in which a plurality of semiconductor layers (a semiconductor layer 101a and a semiconductor layer 101b in the examples illustrated in Figs. 31 and 32) is stacked.

[0186] In the examples illustrated in Figs. 31 and 32, the substrate 201 includes the semiconductor layer 101a, a layer 112, the semiconductor layer 101b, and the wiring layer 111. The semiconductor layer 101b may be configured, for example, by a silicon layer (i.e., Active layer) in the SOI substrate. It is to be noted that the layer 112 is provided, for example, as a wiring layer or an insulating layer. The layer 112 is also referred to as a wiring layer 112.

[0187] The semiconductor layer 101a of the substrate 201 is provided with the photoelectric conversion section 11 of each of the pixels P. The semiconductor layer 101b is provided with, for example, at least a portion of the above-described readout circuit 15 (see Figs. 3 and 4). Some transistors, of the plurality of transistors of the readout circuit 15, may be arranged in the semiconductor layer 101a, and some other transistors may be arranged in the semiconductor layer 101b.

[0188] As an example, the transistor TG of the pixel P may be provided in the semiconductor layer 101a, and at least some of the transistors AMP, SEL, and RST may be provided in the semiconductor layer 101b. The imaging device 1 may have a structure that is advantageous to miniaturization of a pixel. It is to be noted that a portion of the processing circuit 200 may be provided in the semiconductor layer 101b and the wiring layer 111.

[0189] In addition, at least a portion of the optical circuit 300 is provided in the semiconductor layer 101b and the wiring layer 111. For example, as in the example illustrated in Fig. 31 or 32, the modulator 40, the light receiver 50, the waveguide 72, and the like may be provided in the semiconductor layer 101b. In addition, for example, the light source 30 including the light-emitting element 31 may be disposed on the semiconductor layer 101b.

[0190] The imaging device 1 may include a light-blocking member 65, as in the example illustrated in Fig. 31 or the like. The light-blocking member 65 is a light-blocking section (light-blocking film) configured by a member that blocks light. The light-blocking member 65 (light-blocking film) is provided above the optical circuit 300. In the example illustrated in Fig. 31 or the like, the light-blocking member 65 is formed on the side of the surface 11S2 of the semiconductor layer 101a. In the imaging device 1, providing the light-blocking member 65 makes it possible to suppress incidence of unnecessary light on each element of the optical circuit 300.

[0191] It is to be noted that the imaging device 1 may include the above-described light-blocking member 60 instead of or in addition to the light-blocking member 65. In the case of the example illustrated in Fig. 31 or 32, for example, the light-blocking member 60 is provided in the wiring layer 112 of the substrate 201, and is positioned between the semiconductor layer 101a and the optical circuit 300. The light-blocking member 60 may be formed in the wiring layer 112 to cover a portion or all of the optical circuit 300 in a plan view. (2-7. Modification Example 7)

[0192] Figs. 33 and 34 are each an explanatory diagram of a configuration example of an imaging device according to Modification Example 7. The imaging device 1 may have a structure in which four or more substrates are stacked. As in the example illustrated in Fig. 33 or 34, for example, the imaging device 1 includes the substrate 201 to a substrate 205. In addition, the imaging device 1 may include a substrate 206 as a support substrate.

[0193] The substrate 204 and the substrate 205 are, for example, each a semiconductor chip, and are each a processor, a memory, a sensor, another integrated circuit, or the like. As an example, one of the substrate 204 or the substrate 205 may be a chip configured by a logic circuit, such as a DSP (Digital Signal Processor) or an FPGA (Field Programmable Gate Array). In addition, the other of the substrate 204 or the substrate 205 may be a chip configured by a storage circuit, such as a DRAM (Dynamic Random Access Memory) or an SRAM (Static Random Access Memory).

[0194] In the example illustrated in Fig. 33 or the like, the substrate 204 and the substrate 205 are stacked on the substrate 203. The substrate 204 and the substrate 205 are each disposed to be stacked on the side of the surface 13S2 of the substrate 203. As in the example illustrated in Fig. 33, for example, each of the substrate 204 and the substrate 205 is stacked on the substrate 203 by bonding between electrodes (electrodes 95 and 96). It is to be noted that each of the substrates 204 and 205 may have a structure in which a plurality of semiconductor layers is stacked.

[0195] In the imaging device 1, a circuit (e.g., arithmetic circuit) of the substrate 204 is electrically coupled to the optical circuit 300 via the electrodes 95 and 96, the through-electrode 80, and the like. The imaging device 1 is configured to be able to execute communication between the circuit of the substrate 204 and a circuit of an external device, for example, by transmission and reception of optical signals utilizing the optical circuit 300 and the transmission path 75.

[0196] In addition, in the imaging device 1, a circuit (e.g., storage circuit) of the substrate 205 is electrically coupled to the optical circuit 300 via the electrodes 95 and 96, the through-electrode 80, and the like. The imaging device 1 is configured to be able to execute communication between the circuit of the substrate 205 and the circuit of the external device, for example, by transmission and reception of optical signals utilizing the optical circuit 300 and the transmission path 75.

[0197] According to the imaging device 1 of the present modification example, it is possible to adopt an optical signal for performing all of communications between the external device and the circuit (such as processing circuit 200, arithmetic circuit, or storage circuit) of each substrate of the imaging device 1. For example, it is possible to perform high-speed communication between the external device and the arithmetic circuit or the storage circuit, thus making it possible to significantly improve processing capacity.

[0198] Figs. 35 and 36 are each an explanatory diagram of another configuration example of the imaging device according to Modification Example 7. The imaging device 1 may have a configuration in which a plurality of substrates is individually stacked on the substrate 203 provided with the optical circuit 300. For example, the substrate 202, on which the substrate 201 is stacked, the substrate 204, and the substrate 205 are arranged on different regions on one surface of the substrate 203.

[0199] As in the example illustrated in Fig. 35 or 36, a size of the substrate 203 (e.g., an area on the XY plane) is larger a size (an area on the XY plane) of each of the substrates 201, 202, 204, and 205. In the example illustrated in Fig. 35 or the like, the substrate 201 and the substrate 202 are stacked on a region R1 of the substrate 203.

[0200] In addition, the substrate 204 (e.g., arithmetic circuit) is stacked on a region R2 of the substrate 203. The substrate 205 (e.g., storage circuit) is stacked on a region R3 of the substrate 203. Each of the substrate 202, the substrate 204, and the substrate 205 is bonded to the substrate 203, for example, by bonding between electrodes. It is to be noted that four or more or five or more substrates may be disposed on the substrate 203.

[0201] Configuring the imaging device 1 as in the example illustrated in Fig. 35 enables the substrate 203 to be used as an interposer (i.e., an interposer substrate), thus making it possible, for example, to dispose the substrate 202, the substrate 204, and the substrate 205 to be disposed distant from each other. This makes it possible to mitigate adverse effects caused by heat generation in each substrate on the imaging device 1.

[0202] Figs. 37 and 38 are each an explanatory diagram of another configuration example of the imaging device according to Modification Example 7. The imaging device 1 may include a substrate 207 as an interposer (interposer substrate). As in the example illustrated in Fig. 37 or 38, for example, the substrate 207 includes one or a plurality of waveguides 72 (in Fig. 37, etc. a waveguide 72a to a waveguide 72c), and is configured as an optical interposer substrate.

[0203] In the imaging device 1, for example, the substrate 203, on which the substrates 201 and 202 are stacked, the substrate 204, and the substrate 205 are separately disposed on the substrate 207. As schematically illustrated in Fig. 37, the substrate 204 and the substrate 205 each include an optical circuit 320. The optical circuit 320 includes, for example, circuits (the modulator 40, the light receiver 50, the amplification circuit, etc.) similar to those of the optical circuit 300. The waveguide 72a to the waveguide 72c are each configured to be able to transmit an optical signal (e.g., an optical signal based on a pixel signal) from the optical circuit 300, an optical signal from the optical circuit 320, or the like.

[0204] In the example illustrated in Fig. 37, the substrate 207 is provided with the light source 30 including the light-emitting element 31 and the waveguide 71. The output light of the light source 30 is transmitted, for example, to the modulator 40 of the substrate 203 via the waveguide 71 of the substrate 207. In addition, the output light of the light source 30 may be transmitted to the optical circuit 320 of the substrate 204 and the optical circuit 320 of the substrate 205 via the waveguide. It is to be noted that the light source 30 may be mounted in the substrate 207 or may be provided in the substrate 203 or another substrate.

[0205] As an example, the optical circuit 300 of the substrate 203, the optical circuit 320 of the substrate 204, and the optical circuit 320 of the substrate 205 are optically coupled to one another by the waveguide 72a to the waveguide 72c. For example, the circuits provided in the substrate 203 to the substrate 205 are optically coupled (bonded) to one another by evanescent coupling, an antenna, a three-dimensionally structured waveguide, or the like.

[0206] In the imaging device 1, for example, the optical circuit 300 of the substrate 203 performs communication of optical signals with the optical circuit 320 of the substrate 204 or the optical circuit 320 of the substrate 205 via the waveguide 72a. In addition, the optical circuit 320 of the substrate 204 performs communication of optical signals with the optical circuit 320 of the substrate 205 via the waveguide 72b.

[0207] As described above, the imaging device 1 performs communication among the circuit (e.g., processing circuit 200) of the substrate 202, the circuit (e.g., arithmetic circuit) of the substrate 204, and the circuit (e.g., storage circuit) of the substrate 205 by transmission and reception of optical signals utilizing the optical circuits 300 and 320 and the waveguides 72a to 72c. In addition, the imaging device 1 may perform communication between the circuit of each substrate and the circuit of the external device by transmission and reception of optical signals via the waveguide 72c and the transmission path 75.

[0208] As described above, the imaging device 1 may have a configuration (i.e., a chiplet configuration) in which the plurality of substrates is coupled together via the substrate 207 as the optical interposer substrate. It is possible to achieve an imaging device (photodetector) that enables suitable communication. In addition, for example, it is possible to dispose the substrate 202, the substrate 204, and the substrate 205 to be distant from one another, thus making it possible to suppress adverse effects caused by heat generation of each substrate on the imaging device 1. <3. Application Example>

[0209] The above-described imaging device 1 or the like is applicable, for example, to any type of electronic apparatus with an imaging function including a camera system such as a digital still camera or a video camera, a mobile phone having an imaging function, and the like. Fig. 39 illustrates a schematic configuration of an electronic apparatus 1000.

[0210] The electronic apparatus 1000 includes, for example, a lens group 1001, the imaging device 1, a DSP (Digital Signal Processor) circuit 1002, a frame memory 1003, a display unit 1004, a recording unit 1005, an operation unit 1006, and a power supply unit 1007. They are coupled to each other via a bus line 1008.

[0211] The lens group 1001 takes in incident light (image light) from a subject, and forms an image on an imaging surface of the imaging device 1. The imaging device 1 converts the amount of incident light formed as an image on the imaging surface by the lens group 1001 into electric signals on a pixel-by-pixel basis, and supplies the DSP circuit 1002 with the electric signals as pixel signals.

[0212] The DSP circuit 1002 is a signal processing circuit that processes signals supplied from the imaging device 1. The DSP circuit 1002 outputs image data obtained by processing the signals from the imaging device 1. The frame memory 1003 temporarily holds the image data processed by the DSP circuit 1002 on a frame-by-frame basis.

[0213] The display unit 1004 includes, for example, a panel-type display device such as a liquid crystal panel or an organic EL (Electro Luminescence) panel, and records image data of a moving image or a still image captured by the imaging device 1 in a recording medium such as a semiconductor memory or a hard disk.

[0214] The operation unit 1006 outputs an operation signal for a variety of functions of the electronic apparatus 1000 in accordance with an operation by a user. The power supply unit 1007 appropriately supplies the DSP circuit 1002, the frame memory 1003, the display unit 1004, the recording unit 1005, and the operation unit 1006 with various kinds of power for operations of these supply targets.

[0215] The imaging device 1 may convert a pixel signal obtained as an electric signal into an optical signal, and supply the pixel signal converted into the optical signal to the DSP circuit 1002. As in the example illustrated in Fig. 40, the imaging device 1 may output the pixel signal converted into the optical signal to the bus line 1008. It is also possible for the imaging device 1 to broadcast the signal to a plurality of circuits including the DSP circuit 1002. <4. Practical Application Examples> (Example of Practical Application to Mobile Body)

[0216] The technology (the present technology) according to the present disclosure is applicable to a variety of products. For example, the technology according to the present disclosure may be achieved as a device mounted on any type of mobile body such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility, an aircraft, a drone, a vessel, or a robot.

[0217] Fig. 41 is a block diagram depicting an example of schematic configuration of a vehicle control system as an example of a mobile body control system to which the technology according to an embodiment of the present disclosure can be applied.

[0218] The vehicle control system 12000 includes a plurality of electronic control units connected to each other via a communication network 12001. In the example depicted in Fig. 41, the vehicle control system 12000 includes a driving system control unit 12010, a body system control unit 12020, an outside-vehicle information detecting unit 12030, an in-vehicle information detecting unit 12040, and an integrated control unit 12050. In addition, a microcomputer 12051, a sound / image output section 12052, and a vehicle-mounted network interface (I / F) 12053 are illustrated as a functional configuration of the integrated control unit 12050.

[0219] The driving system control unit 12010 controls the operation of devices related to the driving system of the vehicle in accordance with various kinds of programs. For example, the driving system control unit 12010 functions as a control device for a driving force generating device for generating the driving force of the vehicle, such as an internal combustion engine, a driving motor, or the like, a driving force transmitting mechanism for transmitting the driving force to wheels, a steering mechanism for adjusting the steering angle of the vehicle, a braking device for generating the braking force of the vehicle, and the like.

[0220] The body system control unit 12020 controls the operation of various kinds of devices provided to a vehicle body in accordance with various kinds of 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 kinds of lamps such as a headlamp, a backup lamp, a brake lamp, a turn signal, a fog lamp, or the like. In this case, radio waves transmitted from a mobile device as an alternative to a key or signals of various kinds of switches can be input to the body system control unit 12020. The body system control unit 12020 receives these input radio waves or signals, and controls a door lock device, the power window device, the lamps, or the like of the vehicle.

[0221] The outside-vehicle information detecting unit 12030 detects information about the outside of the vehicle including the vehicle control system 12000. For example, the outside-vehicle information detecting unit 12030 is connected with an imaging section 12031. The outside-vehicle information detecting unit 12030 makes the imaging section 12031 image an image of the outside of the vehicle, and receives the imaged image. On the basis of the received image, the outside-vehicle information detecting unit 12030 may perform processing of detecting an object such as a human, a vehicle, an obstacle, a sign, a character on a road surface, or the like, or processing of detecting a distance thereto.

[0222] The imaging section 12031 is an optical sensor that receives light, and which outputs an electric signal corresponding to a received light amount of the light. The imaging section 12031 can output the electric signal as an image, or can output the electric signal as information about a measured distance. In addition, the light received by the imaging section 12031 may be visible light, or may be invisible light such as infrared rays or the like.

[0223] The in-vehicle information detecting unit 12040 detects information about the inside of the vehicle. The in-vehicle information detecting unit 12040 is, for example, connected with a driver state detecting section 12041 that detects the state of a driver. The driver state detecting section 12041, for example, includes a camera that images the driver. On the basis of detection information input from the driver state detecting section 12041, the in-vehicle information detecting unit 12040 may calculate a degree of fatigue of the driver or a degree of concentration of the driver, or may determine whether the driver is dozing.

[0224] The microcomputer 12051 can calculate a control target value for the driving force generating device, the steering mechanism, or the braking device on the basis of the information about the inside or outside of the vehicle which information is obtained by the outside-vehicle information detecting unit 12030 or the in-vehicle information detecting unit 12040, and output a control command to the driving system control unit 12010. For example, the microcomputer 12051 can perform cooperative control intended to implement functions of an advanced driver assistance system (ADAS) which functions include collision avoidance or shock mitigation for the vehicle, following driving based on a following distance, vehicle speed maintaining driving, a warning of collision of the vehicle, a warning of deviation of the vehicle from a lane, or the like.

[0225] In addition, the microcomputer 12051 can perform cooperative control intended for automated driving, which makes the vehicle to travel automatedly without depending on the operation of the driver, or the like, by controlling the driving force generating device, the steering mechanism, the braking device, or the like on the basis of the information about the outside or inside of the vehicle which information is obtained by the outside-vehicle information detecting unit 12030 or the in-vehicle information detecting unit 12040.

[0226] In addition, the microcomputer 12051 can output a control command to the body system control unit 12020 on the basis of the information about the outside of the vehicle which information is obtained by the outside-vehicle information detecting unit 12030. For example, the microcomputer 12051 can perform cooperative control intended to prevent a glare by controlling the headlamp so as to change from a high beam to a low beam, for example, in accordance with the position of a preceding vehicle or an oncoming vehicle detected by the outside-vehicle information detecting unit 12030.

[0227] The sound / image output section 12052 transmits an output signal of at least one of a sound and an image to an output device capable of visually or auditorily notifying information to an occupant of the vehicle or the outside of the vehicle. In the example of Fig. 41, an audio speaker 12061, a display section 12062, and an instrument panel 12063 are illustrated as the output device. The display section 12062 may, for example, include at least one of an on-board display and a head-up display.

[0228] Fig. 42 is a diagram depicting an example of the installation position of the imaging section 12031.

[0229] In Fig. 42, the imaging section 12031 includes imaging sections 12101, 12102, 12103, 12104, and 12105.

[0230] The imaging sections 12101, 12102, 12103, 12104, and 12105 are, for example, disposed at positions on a front nose, sideview mirrors, a rear bumper, and a back door of the vehicle 12100 as well as a position on an upper portion of a windshield within the interior of the vehicle. The imaging section 12101 provided to the front nose and the imaging section 12105 provided to the upper portion of the windshield within the interior of the vehicle obtain mainly an image of the front of the vehicle 12100. The imaging sections 12102 and 12103 provided to the sideview mirrors obtain mainly an image of the sides of the vehicle 12100. The imaging section 12104 provided to the rear bumper or the back door obtains mainly an image of the rear of the vehicle 12100. The imaging section 12105 provided to the upper portion of the windshield within the interior of the vehicle is used mainly to detect a preceding vehicle, a pedestrian, an obstacle, a signal, a traffic sign, a lane, or the like.

[0231] Incidentally, Fig. 42 depicts an example of photographing ranges of the imaging sections 12101 to 12104. An imaging range 12111 represents the imaging range of the imaging section 12101 provided to the front nose. Imaging ranges 12112 and 12113 respectively represent the imaging ranges of the imaging sections 12102 and 12103 provided to the sideview mirrors. An imaging range 12114 represents the imaging range of the imaging section 12104 provided to the rear bumper or the back door. A bird’s-eye image of the vehicle 12100 as viewed from above is obtained by superimposing image data imaged by the imaging sections 12101 to 12104, for example.

[0232] At least one of the imaging sections 12101 to 12104 may have a function of obtaining distance information. For example, at least one of the imaging sections 12101 to 12104 may be a stereo camera constituted of a plurality of imaging elements, or may be an imaging element having pixels for phase difference detection.

[0233] For example, the microcomputer 12051 can determine a distance to each three-dimensional object within the imaging ranges 12111 to 12114 and a temporal change in the distance (relative speed with respect to the vehicle 12100) on the basis of the distance information obtained from the imaging sections 12101 to 12104, and thereby extract, as a preceding vehicle, a nearest three-dimensional object in particular that is present on a traveling path of the vehicle 12100 and which travels in substantially the same direction as the vehicle 12100 at a predetermined speed (for example, equal to or more than 0 km / hour). Further, the microcomputer 12051 can set a following distance to be maintained in front of a preceding vehicle in advance, and perform automatic brake control (including following stop control), automatic acceleration control (including following start control), or the like. It is thus possible to perform cooperative control intended for automated driving that makes the vehicle travel automatedly without depending on the operation of the driver or the like.

[0234] For example, the microcomputer 12051 can classify three-dimensional object data on three-dimensional objects into three-dimensional object data of a two-wheeled vehicle, a standard-sized vehicle, a large-sized vehicle, a pedestrian, a utility pole, and other three-dimensional objects on the basis of the distance information obtained from the imaging sections 12101 to 12104, extract the classified three-dimensional object data, and use the extracted three-dimensional object data for automatic avoidance of an obstacle. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 as obstacles that the driver of the vehicle 12100 can recognize visually and obstacles that are difficult for the driver of the vehicle 12100 to recognize visually. Then, the microcomputer 12051 determines a collision risk indicating a risk of collision with each obstacle. In a situation in which the collision risk is equal to or higher than a set value and there is thus a possibility of collision, the microcomputer 12051 outputs a warning to the driver via the audio speaker 12061 or the display section 12062, and performs forced deceleration or avoidance steering via the driving system control unit 12010. The microcomputer 12051 can thereby assist in driving to avoid collision.

[0235] At least one of the imaging sections 12101 to 12104 may be an infrared camera that detects infrared rays. The microcomputer 12051 can, for example, recognize a pedestrian by determining whether or not there is a pedestrian in imaged images of the imaging sections 12101 to 12104. Such recognition of a pedestrian is, for example, performed by a procedure of extracting characteristic points in the imaged images of the imaging sections 12101 to 12104 as infrared cameras and a procedure of determining whether or not it is the pedestrian by performing pattern matching processing on a series of characteristic points representing the contour of the object. When the microcomputer 12051 determines that there is a pedestrian in the imaged images of the imaging sections 12101 to 12104, and thus recognizes the pedestrian, the sound / image output section 12052 controls the display section 12062 so that a square contour line for emphasis is displayed so as to be superimposed on the recognized pedestrian. The sound / image output section 12052 may also control the display section 12062 so that an icon or the like representing the pedestrian is displayed at a desired position.

[0236] The description has been given hereinabove of the mobile body control system to which the technology according to an embodiment of the present disclosure is applicable. The technology according to an embodiment of the present disclosure is applicable to the imaging section 12031, for example, of the configurations described above. Specifically, for example, the imaging device 1 or the like can be applied to the imaging section 12031. Applying the technology according to an embodiment of the present disclosure to the imaging section 12031 enables obtainment of a photographed image having high definition. It becomes possible to perform highly accurate control utilizing the photographed image in the mobile body control system.

[0237] The imaging section 12031 to which the above-described imaging device 1 is applied may convert an electric signal corresponding to a received light amount into an optical signal and output the optical signal. The imaging section 12031 (e.g., the imaging sections 12101 to 12105) can output the optical signal as image information, or can output the optical signal as information about a measured distance.

[0238] As in the example illustrated in Fig. 43, for example, the imaging section 12031 is connected, via the communication network 12001, to the driving system control unit 12010, the body system control unit 12020, the outside-vehicle information detecting unit 12030, the in-vehicle information detecting unit 12040, and the integrated control unit 12050.

[0239] The microcomputer 12051 may receive signals from the imaging section 12031 without passing through the outside-vehicle information detecting unit 12030 to detect information about the outside of the vehicle. For example, the microcomputer 12051 may perform, on the basis of the signals received from the imaging section 12031, processing of detecting an object such as a human, a vehicle, an obstacle, a sign, a character on a road surface, or the like, or processing of detecting a distance thereto. (Example of Practical Application to Endoscopic Surgery System)

[0240] The technology according to an embodiment of the present disclosure (present technology) is applicable to various products. For example, the technology according to an embodiment of the present disclosure may be applied to an endoscopic surgery system.

[0241] Fig. 44 is a view depicting an example of a schematic configuration of an endoscopic surgery system to which the technology according to an embodiment of the present disclosure (present technology) can be applied.

[0242] In Fig. 44, a state is illustrated in which a surgeon (medical doctor) 11131 is using an endoscopic surgery system 11000 to perform surgery for a patient 11132 on a patient bed 11133. As depicted, the endoscopic surgery system 11000 includes an endoscope 11100, other surgical tools 11110 such as a pneumoperitoneum tube 11111 and an energy device 11112, a supporting arm apparatus 11120 which supports the endoscope 11100 thereon, and a cart 11200 on which various apparatus for endoscopic surgery are mounted.

[0243] The endoscope 11100 includes a lens barrel 11101 having a region of a predetermined length from a distal end thereof to be inserted into a body cavity of the patient 11132, and a camera head 11102 connected to a proximal end of the lens barrel 11101. In the example depicted, the endoscope 11100 is depicted which includes as a rigid endoscope having the lens barrel 11101 of the hard type. However, the endoscope 11100 may otherwise be included as a flexible endoscope having the lens barrel 11101 of the flexible type.

[0244] The lens barrel 11101 has, at a distal end thereof, an opening in which an objective lens is fitted. A light source apparatus 11203 is connected to the endoscope 11100 such that light generated by the light source apparatus 11203 is introduced to a distal end of the lens barrel 11101 by a light guide extending in the inside of the lens barrel 11101 and is irradiated toward an observation target in a body cavity of the patient 11132 through the objective lens. It is to be noted that the endoscope 11100 may be a forward-viewing endoscope or may be an oblique-viewing endoscope or a side-viewing endoscope.

[0245] An optical system and an image pickup element are provided in the inside of the camera head 11102 such that reflected light (observation light) from the observation target is condensed on the image pickup element by the optical system. The observation light is photo-electrically converted by the image pickup element to generate an electric signal corresponding to the observation light, namely, an image signal corresponding to an observation image. The image signal is transmitted as RAW data to a CCU 11201.

[0246] The CCU 11201 includes a central processing unit (CPU), a graphics processing unit (GPU) or the like and integrally controls operation of the endoscope 11100 and a display apparatus 11202. Further, the CCU 11201 receives an image signal from the camera head 11102 and performs, for the image signal, various image processes for displaying an image based on the image signal such as, for example, a development process (demosaic process).

[0247] The display apparatus 11202 displays thereon an image based on an image signal, for which the image processes have been performed by the CCU 11201, under the control of the CCU 11201.

[0248] The light source apparatus 11203 includes a light source such as, for example, a light emitting diode (LED) and supplies irradiation light upon imaging of a surgical region to the endoscope 11100.

[0249] An inputting apparatus 11204 is an input interface for the endoscopic surgery system 11000. A user can perform inputting of various kinds of information or instruction inputting to the endoscopic surgery system 11000 through the inputting apparatus 11204. For example, the user would input an instruction or a like to change an image pickup condition (type of irradiation light, magnification, focal distance or the like) by the endoscope 11100.

[0250] A treatment tool controlling apparatus 11205 controls driving of the energy device 11112 for cautery or incision of a tissue, sealing of a blood vessel or the like. A pneumoperitoneum apparatus 11206 feeds gas into a body cavity of the patient 11132 through the pneumoperitoneum tube 11111 to inflate the body cavity in order to secure the field of view of the endoscope 11100 and secure the working space for the surgeon. A recorder 11207 is an apparatus capable of recording various kinds of information relating to surgery. A printer 11208 is an apparatus capable of printing various kinds of information relating to surgery in various forms such as a text, an image or a graph.

[0251] It is to be noted that the light source apparatus 11203 which supplies irradiation light when a surgical region is to be imaged to the endoscope 11100 may include a white light source which includes, for example, an LED, a laser light source or a combination of them. Where a white light source includes a combination of red, green, and blue (RGB) laser light sources, since the output intensity and the output timing can be controlled with a high degree of accuracy for each color (each wavelength), adjustment of the white balance of a picked up image can be performed by the light source apparatus 11203. Further, in this case, if laser beams from the respective RGB laser light sources are irradiated time-divisionally on an observation target and driving of the image pickup elements of the camera head 11102 are controlled in synchronism with the irradiation timings. Then images individually corresponding to the R, G and B colors can be also picked up time-divisionally. According to this method, a color image can be obtained even if color filters are not provided for the image pickup element.

[0252] Further, the light source apparatus 11203 may be controlled such that the intensity of light to be outputted is changed for each predetermined time. By controlling driving of the image pickup element of the camera head 11102 in synchronism with the timing of the change of the intensity of light to acquire images time-divisionally and synthesizing the images, an image of a high dynamic range free from underexposed blocked up shadows and overexposed highlights can be created.

[0253] Further, the light source apparatus 11203 may be configured to supply light of a predetermined wavelength band ready for special light observation. In special light observation, for example, by utilizing the wavelength dependency of absorption of light in a body tissue to irradiate light of a narrow band in comparison with irradiation light upon ordinary observation (namely, white light), narrow band observation (narrow band imaging) of imaging a predetermined tissue such as a blood vessel of a superficial portion of the mucous membrane or the like in a high contrast is performed. Alternatively, in special light observation, fluorescent observation for obtaining an image from fluorescent light generated by irradiation of excitation light may be performed. In fluorescent observation, it is possible to perform observation of fluorescent light from a body tissue by irradiating excitation light on the body tissue (autofluorescence observation) or to obtain a fluorescent light image by locally injecting a reagent such as indocyanine green (ICG) into a body tissue and irradiating excitation light corresponding to a fluorescent light wavelength of the reagent upon the body tissue. The light source apparatus 11203 can be configured to supply such narrow-band light and / or excitation light suitable for special light observation as described above.

[0254] Fig. 45 is a block diagram depicting an example of a functional configuration of the camera head 11102 and the CCU 11201 depicted in Fig. 44.

[0255] The camera head 11102 includes a lens unit 11401, an image pickup unit 11402, a driving unit 11403, a communication unit 11404 and a camera head controlling unit 11405. The CCU 11201 includes a communication unit 11411, an image processing unit 11412 and a control unit 11413. The camera head 11102 and the CCU 11201 are connected for communication to each other by a transmission cable 11400.

[0256] The lens unit 11401 is an optical system, provided at a connecting location to the lens barrel 11101. Observation light taken in from a distal end of the lens barrel 11101 is guided to the camera head 11102 and introduced into the lens unit 11401. The lens unit 11401 includes a combination of a plurality of lenses including a zoom lens and a focusing lens.

[0257] The number of image pickup elements which is included by the image pickup unit 11402 may be one (single-plate type) or a plural number (multi-plate type). Where the image pickup unit 11402 is configured as that of the multi-plate type, for example, image signals corresponding to respective R, G and B are generated by the image pickup elements, and the image signals may be synthesized to obtain a color image. The image pickup unit 11402 may also be configured so as to have a pair of image pickup elements for acquiring respective image signals for the right eye and the left eye ready for three dimensional (3D) display. If 3D display is performed, then the depth of a living body tissue in a surgical region can be comprehended more accurately by the surgeon 11131. It is to be noted that, where the image pickup unit 11402 is configured as that of stereoscopic type, a plurality of systems of lens units 11401 are provided corresponding to the individual image pickup elements.

[0258] Further, the image pickup unit 11402 may not necessarily be provided on the camera head 11102. For example, the image pickup unit 11402 may be provided immediately behind the objective lens in the inside of the lens barrel 11101.

[0259] The driving unit 11403 includes an actuator and moves the zoom lens and the focusing lens of the lens unit 11401 by a predetermined distance along an optical axis under the control of the camera head controlling unit 11405. Consequently, the magnification and the focal point of a picked up image by the image pickup unit 11402 can be adjusted suitably.

[0260] The communication unit 11404 includes a communication apparatus for transmitting and receiving various kinds of information to and from the CCU 11201. The communication unit 11404 transmits an image signal acquired from the image pickup unit 11402 as RAW data to the CCU 11201 through the transmission cable 11400.

[0261] In addition, the communication unit 11404 receives a control signal for controlling driving of the camera head 11102 from the CCU 11201 and supplies the control signal to the camera head controlling unit 11405. The control signal includes information relating to image pickup conditions such as, for example, information that a frame rate of a picked up image is designated, information that an exposure value upon image picking up is designated and / or information that a magnification and a focal point of a picked up image are designated.

[0262] It is to be noted that the image pickup conditions such as the frame rate, exposure value, magnification or focal point may be designated by the user or may be set automatically by the control unit 11413 of the CCU 11201 on the basis of an acquired image signal. In the latter case, an auto exposure (AE) function, an auto focus (AF) function and an auto white balance (AWB) function are incorporated in the endoscope 11100.

[0263] The camera head controlling unit 11405 controls driving of the camera head 11102 on the basis of a control signal from the CCU 11201 received through the communication unit 11404.

[0264] The communication unit 11411 includes a communication apparatus for transmitting and receiving various kinds of information to and from the camera head 11102. The communication unit 11411 receives an image signal transmitted thereto from the camera head 11102 through the transmission cable 11400.

[0265] Further, the communication unit 11411 transmits a control signal for controlling driving of the camera head 11102 to the camera head 11102. The image signal and the control signal can be transmitted by electrical communication, optical communication or the like.

[0266] The image processing unit 11412 performs various image processes for an image signal in the form of RAW data transmitted thereto from the camera head 11102.

[0267] The control unit 11413 performs various kinds of control relating to image picking up of a surgical region or the like by the endoscope 11100 and display of a picked up image obtained by image picking up of the surgical region or the like. For example, the control unit 11413 creates a control signal for controlling driving of the camera head 11102.

[0268] Further, the control unit 11413 controls, on the basis of an image signal for which image processes have been performed by the image processing unit 11412, the display apparatus 11202 to display a picked up image in which the surgical region or the like is imaged. Thereupon, the control unit 11413 may recognize various objects in the picked up image using various image recognition technologies. For example, the control unit 11413 can recognize a surgical tool such as forceps, a particular living body region, bleeding, mist when the energy device 11112 is used and so forth by detecting the shape, color and so forth of edges of objects included in a picked up image. The control unit 11413 may cause, when it controls the display apparatus 11202 to display a picked up image, various kinds of surgery supporting information to be displayed in an overlapping manner with an image of the surgical region using a result of the recognition. Where surgery supporting information is displayed in an overlapping manner and presented to the surgeon 11131, the burden on the surgeon 11131 can be reduced and the surgeon 11131 can proceed with the surgery with certainty.

[0269] The transmission cable 11400 which connects the camera head 11102 and the CCU 11201 to each other is an electric signal cable ready for communication of an electric signal, an optical fiber ready for optical communication or a composite cable ready for both of electrical and optical communications.

[0270] Here, while, in the example depicted, communication is performed by wired communication using the transmission cable 11400, the communication between the camera head 11102 and the CCU 11201 may be performed by wireless communication.

[0271] The description has been given hereinabove of one example of the endoscopic surgery system, to which the technology according to an embodiment of the present disclosure is applicable. The technology according to an embodiment of the present disclosure is suitably applicable to, for example, the image pickup unit 11402 provided in the camera head 11102 of the endoscope 11100 of the configurations described above. Applying the technology according to an embodiment of the present disclosure to the image pickup unit 11402 makes it possible to provide the endoscope 11100 having high definition.

[0272] The image pickup unit 11402 to which the above-described imaging device 1 is applied may convert an electric signal corresponding to the observation light into an optical signal, and may output the optical signal. The image pickup unit 11402 may include the above-described communication unit 11404, as in the example illustrated in Fig. 46. The imaging device 1, the optical circuit 300, and the like may be applied to the image pickup unit 11402 and the communication unit 11404, for example. The image pickup unit 11402 can transmit and receive the image signal or the control signal by optical communication, electrical communication, or the like.

[0273] Although the description has been given hereinabove of the present disclosure with reference to the embodiment, the modification examples, the application example, and the practical application examples, the present technology is not limited to the foregoing embodiment and the like, and may be modified in a wide variety of ways. For example, although the foregoing modification examples have been described as modification examples of the foregoing embodiments, the configurations of the respective modification examples may be combined as appropriate.

[0274] In the foregoing embodiments and the like, the imaging device has been exemplified for description. However, it is sufficient for the photodetector of the present disclosure to be, for example, a device that receives incident light and converts the light into electric charge. A signal to be outputted may be a signal of image information or a signal of information on a measured distance. The photodetector (imaging device) is applicable to an image sensor, a distance measurement sensor, or the like. It is to be noted that the present disclosure is not limited to a back side illumination image sensor, and is also applicable to a front side illumination image sensor.

[0275] The photodetector according to the present disclosure is also applicable as a distance measurement sensor that enables distance measurement of a TOF (Time Of Flight) method. The photodetector (imaging device) is also applicable as a sensor that is able to detect an event, e.g., an event-driven sensor (referred to as EVS (Event Vision Sensor), EDS (Event Driven Sensor), DVS (Dynamic Vision Sensor), etc.).

[0276] The photodetector according to an embodiment of the present disclosure includes: a first substrate including a photoelectric conversion element; a second substrate including at least a portion of a processing circuit configured to execute signal processing of a first signal generated on the basis of electric charge converted by the photoelectric conversion element, the second substrate being stacked on the first substrate; and an optical circuit configured to output a first optical signal based on the first signal. It is therefore possible to achieve a photodetector that enables suitable communication.

[0277] The photodetection system according to an embodiment of the present disclosure includes: a photodetector and an external device. The photodetector includes: a first substrate including a photoelectric conversion element; a second substrate including at least a portion of a processing circuit configured to execute signal processing of a first signal generated on the basis of electric charge converted by the photoelectric conversion element, the second substrate being stacked on the first substrate; and an optical circuit configured to transmit, to the external device, a first optical signal based on the first signal. It is therefore possible to achieve a photodetection system that enables suitable communication.

[0278] It is to be noted that the effects described herein are merely exemplary and are not limited to the description, and may further include other effects. In addition, the present disclosure may also have the following configurations. (1) A semiconductor device, comprising: a first semiconductor substrate, includes a readout circuit and a photoelectric conversion section; a second semiconductor substrate, wherein the second semiconductor substrate includes a processing circuit; and a third semiconductor substrate, wherein the third semiconductor substrate includes an optical circuit, wherein the first semiconductor substrate, the second semiconductor substrate, and the third semiconductor substrate are stacked with one another. (2) The semiconductor device according to (1), wherein the optical circuit includes a light source, a modulator, and a waveguide. (3) The semiconductor device according to (2), wherein the second semiconductor substrate includes an interface circuit, and wherein the interface circuit overlaps at least a portion of the modulator of the optical circuit. (4) The semiconductor device according to (3), wherein a plurality of through electrodes are provided in an electrode region of the second semiconductor substrate and in an electrode region of the third semiconductor substrate. (5) The semiconductor device according to (4), wherein the electrode region of the second semiconductor substrate is in a peripheral region of the processing circuit. (6) The semiconductor device according to (5), wherein the interface circuit is adjacent to the electrode region of the second semiconductor substrate. (7) The semiconductor device according to (2), wherein the light source is electrically coupled to the processing circuit by an electrode. (8) The semiconductor device according to (7), wherein the modulator receives light from the light source and an electrical signal from the processing circuit, and wherein the modulator outputs a modulated optical signal. (9) The semiconductor device according to (8), wherein the waveguide receives the modulated optical signal from the modulator and transmits the modulated optical signal to a transmission path coupled to the waveguide. (10) The semiconductor device according to (2), further comprising: a light-blocking member, wherein the light blocking member is positioned between the at least a portion of the optical circuit and the second semiconductor substrate. (11) The semiconductor device according to (10), wherein the light-blocking member is disposed in a plurality of layers. (12) The semiconductor device according to (1), wherein the second semiconductor substrate is between the first semiconductor substrate and the third semiconductor substrate. (13) The semiconductor device according to (1), wherein the third semiconductor substrate is between the first semiconductor substrate and the second semiconductor substrate. (14) A photodetection system, comprising: an imaging device, including: a first semiconductor substrate, includes a readout circuit and a photoelectric conversion section; a second semiconductor substrate, wherein the second semiconductor substrate includes a processing circuit; and a third semiconductor substrate, wherein the third semiconductor substrate includes an optical circuit, wherein the first semiconductor substrate, the second semiconductor substrate, and the third semiconductor substrate are stacked with one another; a transmission path; and an external device, including: an optical circuit, wherein the transmission path connects the optical circuit of the imaging device to an optical circuit of the external device. (15) The photodetection system according to (14), wherein the imaging device is operable to: convert light received at the photoelectric conversion in the first semiconductor substrate to an analog electrical signal, pass the analog electrical signal from the first semiconductor substrate to the second semiconductor substrate through wirings convert the analog electrical signal to a digital electrical signal in the second semiconductor substrate, pass the digital electrical signal from the second semiconductor substrate to the third semiconductor substrate over a through-electrode to the optical circuit of the third semiconductor substrate, convert the digital electrical signal to an optical signal in the third semiconductor substrate, and output the digital electrical signal to the transmission path. (16) The photodetection system according to (14), wherein the optical circuit includes a light source, a modulator, and a waveguide. (17) The photodetection system according to (16), wherein the second semiconductor substrate includes an interface circuit, and wherein the interface circuit overlaps at least a portion of the modulator of the optical circuit. (18) The photodetection system according to (17), wherein a plurality of through electrodes are provided in an electrode region of the second semiconductor substrate and in an electrode region of the third semiconductor substrate. (19) The photodetection system according to (18), wherein the electrode region of the second semiconductor substrate is in a peripheral region of the processing circuit. (20) The photodetection system according to (19), wherein the interface circuit is adjacent to the electrode region of the second semiconductor substrate.

[0279] It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.Reference Numerals List

[0280] 1 imaging device 10 photodetection system 11 photoelectric conversion section 30 light source 40 modulator 50 light receiver 200 processing circuit 300 optical circuit

Claims

1. A semiconductor device, comprising: a first semiconductor substrate, includes a readout circuit and a photoelectric conversion section; a second semiconductor substrate, wherein the second semiconductor substrate includes a processing circuit; and a third semiconductor substrate, wherein the third semiconductor substrate includes an optical circuit, wherein the first semiconductor substrate, the second semiconductor substrate, and the third semiconductor substrate are stacked with one another.

2. The semiconductor device according to claim 1, wherein the optical circuit includes a light source, a modulator, and a waveguide.

3. The semiconductor device according to claim 2, wherein the second semiconductor substrate includes an interface circuit, and wherein the interface circuit overlaps at least a portion of the modulator of the optical circuit.

4. The semiconductor device according to claim 3, wherein a plurality of through electrodes are provided in an electrode region of the second semiconductor substrate and in an electrode region of the third semiconductor substrate.

5. The semiconductor device according to claim 4, wherein the electrode region of the second semiconductor substrate is in a peripheral region of the processing circuit.

6. The semiconductor device according to claim 5, wherein the interface circuit is adjacent to the electrode region of the second semiconductor substrate.

7. The semiconductor device according to claim 2, wherein the light source is electrically coupled to the processing circuit by an electrode.

8. The semiconductor device according to claim 7, wherein the modulator receives light from the light source and an electrical signal from the processing circuit, and wherein the modulator outputs a modulated optical signal.

9. The semiconductor device according to claim 8, wherein the waveguide receives the modulated optical signal from the modulator and transmits the modulated optical signal to a transmission path coupled to the waveguide.

10. The semiconductor device according to claim 2, further comprising: a light-blocking member, wherein the light blocking member is positioned between the at least a portion of the optical circuit and the second semiconductor substrate.

11. The semiconductor device according to claim 10, wherein the light-blocking member is disposed in a plurality of layers.

12. The semiconductor device according to claim 1, wherein the second semiconductor substrate is between the first semiconductor substrate and the third semiconductor substrate.

13. The semiconductor device according to claim 1, wherein the third semiconductor substrate is between the first semiconductor substrate and the second semiconductor substrate.

14. A photodetection system, comprising: an imaging device, including: a first semiconductor substrate, includes a readout circuit and a photoelectric conversion section; a second semiconductor substrate, wherein the second semiconductor substrate includes a processing circuit; and a third semiconductor substrate, wherein the third semiconductor substrate includes an optical circuit, wherein the first semiconductor substrate, the second semiconductor substrate, and the third semiconductor substrate are stacked with one another; a transmission path; and an external device, including: an optical circuit, wherein the transmission path connects the optical circuit of the imaging device to an optical circuit of the external device.

15. The photodetection system according to claim 14, wherein the imaging device is operable to: convert light received at the photoelectric conversion in the first semiconductor substrate to an analog electrical signal, pass the analog electrical signal from the first semiconductor substrate to the second semiconductor substrate through wirings convert the analog electrical signal to a digital electrical signal in the second semiconductor substrate, pass the digital electrical signal from the second semiconductor substrate to the third semiconductor substrate over a through-electrode to the optical circuit of the third semiconductor substrate, convert the digital electrical signal to an optical signal in the third semiconductor substrate, and output the digital electrical signal to the transmission path.

16. The photodetection system according to claim 14, wherein the optical circuit includes a light source, a modulator, and a waveguide.

17. The photodetection system according to claim 16, wherein the second semiconductor substrate includes an interface circuit, and wherein the interface circuit overlaps at least a portion of the modulator of the optical circuit.

18. The photodetection system according to claim 17, wherein a plurality of through electrodes are provided in an electrode region of the second semiconductor substrate and in an electrode region of the third semiconductor substrate.

19. The photodetection system according to claim 18, wherein the electrode region of the second semiconductor substrate is in a peripheral region of the processing circuit.

20. The photodetection system according to claim 19, wherein the interface circuit is adjacent to the electrode region of the second semiconductor substrate.

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