Light receiving device and distance measuring device

Abstract

The present invention ensures the amount of current required for electrostatic discharge (ESD) surge protection without relying on a pixel circuit. A light receiving device of the present technology comprises: an effective pixel including a light receiving element for detecting the presence or absence of photons and a pixel readout circuit for processing a signal output by the light receiving element; a first terminal that applies a predetermined voltage to the light receiving element; a second terminal that applies a first power supply voltage to the readout circuit; dummy pixels that do not contribute to the detection of the presence or absence of photons; and a protection circuit that protects the light receiving element and circuit elements of the readout circuit from overvoltage. The protection circuit includes: a dummy pixel light receiving element connected to a first terminal; and a diode element connected between the dummy pixel light receiving element and the second terminal to have a polarity opposite to a polarity of the dummy pixel light receiving element.

Description

Technical Field

[0001] The present technology relates to a light receiving device. Specifically, the present invention relates to a light receiving device including a protection circuit that protects a circuit to be protected from electrostatic discharge (ESD), and a distance measuring device using the light receiving device. Background Art

[0002] As one of the methods for optically measuring the distance to a distance measurement object, a time-of-flight (ToF) method is known. In a distance measurement device based on ToF, the flight time until light emitted from a light source toward the distance measurement object is reflected by the distance measurement object and returns to a light receiving device is measured, and the distance from the distance measurement device to the distance measurement object is measured based on the measured flight time.

[0003] As described above, a ToF-based distance measurement device is equipped with a light receiving device that receives light reflected and returned by a distance measurement object. In the light receiving device, for example, a single photon avalanche diode (SPAD) element that detects the presence or absence of photons is used as a light receiving element.

[0004] Conventionally, a light receiving device is provided with a protection circuit that protects a readout circuit of a pixel including a light receiving element such as a SPAD element from an ESD surge voltage by forming an ESD surge current path in a pixel circuit that processes a signal of a light receiving element such as a SPAD element (for example, see patent document 1).

[0005] Citation List

[0006] Patent Literature

[0007] Patent document 1: WO 2021 / 090569 A Summary of the invention

[0008] Problems to be solved by the present invention

[0009] In the above conventional technology, in order to protect the readout circuit of the pixel including the light receiving element from ESD, a surge current path through which the ESD surge current flows is provided in the pixel circuit. When the surge current path exists in the pixel circuit as described above, the amount of current flowing through the surge current path (i.e., the amount of current required for ESD surge protection) depends on the pixel circuit.

[0010] The present technology has been created in view of such circumstances, and an object thereof is to ensure the amount of current required for ESD surge protection without depending on a pixel circuit.

[0011] Means of solving the problem

[0012] The present technology is produced to solve the above-mentioned problems, and its first aspect is a light receiving device, which includes: an effective pixel, including a light receiving element that detects the presence or absence of photons and a readout circuit of the pixel, the readout circuit processing a signal output from the light receiving element; a dummy pixel, including a light receiving element that does not contribute to the detection of the presence or absence of photons; a first terminal configured to apply a predetermined voltage to the light receiving element of the effective pixel and the light receiving element of the dummy pixel; a second terminal configured to provide a first power supply voltage to the readout circuit; and a protection circuit including a diode element, which is connected between the light receiving element of the dummy pixel and the second terminal in a reverse polarity relationship relative to the light receiving element of the dummy pixel, and protects the light receiving element of the effective pixel and the circuit element of the readout circuit from the influence of overvoltage. Therefore, this brings about the effect that the amount of current required for ESD surge protection can be ensured without depending on the circuit configuration, size, etc. of the pixel circuit.

[0013] Furthermore, in the first aspect, in the effective pixel, the readout circuit of the pixel can be formed in the pixel formation region paired with the light receiving element, and in the dummy pixel, the diode element can be formed in the pixel formation region corresponding to the pixel formation region of the effective pixel. Therefore, since the diode element can be formed as a diode element with a large size in the pixel formation region, a larger amount of current can be ensured as the amount of current required for ESD surge protection.

[0014] Furthermore, in the first aspect, the light receiving element of the effective pixel and the light receiving element of the dummy pixel may be avalanche diodes, for example, single photon avalanche diodes. Therefore, this brings about an effect that a signal can be generated in response to reception of a photon.

[0015] In addition, in the first aspect, a single photon avalanche diode of a dummy pixel adjacent to the dummy pixel to which the diode element belongs can be used as the diode element. Therefore, there is no need to newly form a diode element, and a desired surge current path can be formed only by adding wiring or changing the circuit formation area.

[0016] In addition, in the first aspect, the light receiving device may include: a third terminal configured to apply the second power supply voltage to the readout circuit of the effective pixel; and at least one of a surge current path including a diode element connected to the light receiving element of the dummy pixel in a forward polarity relationship between the first terminal and the second terminal, or a surge current path including a diode element connected to the light receiving element of the dummy pixel in a forward polarity relationship between the first terminal and the third terminal. Therefore, this brings about the effect that a high withstand voltage protection element provided in the pixel circuit is not required.

[0017] In addition, in the first aspect, the readout circuit of the effective pixel can be configured using a thin film transistor. Therefore, this brings about the effect that even in a light receiving device having a pixel circuit including a thin film transistor, the amount of current required for ESD surge protection can be ensured.

[0018] In addition, the second aspect of the present technology is a light receiving device, comprising: a first light receiving element; a quenching element connected between a first node (electrode) as an anode or cathode of the first light receiving element and a node of a first power supply voltage; a transistor connected between a node of the first power supply voltage and a node of a second power supply voltage; a second light receiving element; and a diode element connected between a second node (electrode) as an anode or cathode of the second light receiving element and a node of a second power supply voltage, and connected to the second light receiving element in a reverse polarity relationship. The first light receiving element and the second light receiving element receive a predetermined voltage at a node opposite to the first node and the second node. Therefore, this brings about the effect that the amount of current required for ESD surge protection can be ensured without depending on the circuit configuration, size, etc. of the pixel circuit.

[0019] In addition, in the second aspect, the first light receiving element can be arranged in the effective pixel area, and the second light receiving element can be arranged in the dummy pixel area. Therefore, this has the effect that the second light receiving element in the dummy pixel area can be used to form a surge current path (current path) for causing the ESD surge current to flow.

[0020] In addition, in the second aspect, a first substrate including a first light receiving element and a second light receiving element and a second substrate including a quenching element, a transistor and a diode element may be included. Therefore, this brings about an effect that a stacked semiconductor chip structure can be formed by the first substrate and the second substrate.

[0021] In addition, the third aspect of the present technology is a distance measuring device, which includes: a light source unit that irradiates a distance measurement object with light; and a light receiving device that receives reflected light from the distance measurement object based on the irradiated light from the light source unit. The light receiving device includes: an effective pixel, including a light receiving element that detects the presence or absence of a photon and a readout circuit of the pixel, which processes a signal output from the light receiving element; a dummy pixel, including a light receiving element that does not contribute to the detection of the presence or absence of a photon; a first terminal configured to apply a predetermined voltage to the light receiving element of the effective pixel and the light receiving element of the dummy pixel; a second terminal configured to apply a first power supply voltage to the readout circuit; and a protection circuit including a diode element that is connected between the light receiving element of the dummy pixel and the second terminal in a reverse polarity relationship relative to the light receiving element of the dummy pixel, and protects the light receiving element of the effective pixel and the circuit element of the readout circuit from the influence of overvoltage. Therefore, this brings about the effect that the amount of current required for ESD surge protection can be ensured without depending on the circuit configuration, size, etc. of the pixel circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a conceptual diagram showing an example of a system configuration of a ToF-based distance measurement system.

[0023] Figure 2 is a block diagram showing an embodiment of a basic configuration of a ToF-based distance measurement device.

[0024] Figure 3 is a circuit diagram showing an embodiment of a basic pixel circuit using a SPAD element.

[0025] Figure 4 is a diagram for explaining the current-voltage characteristics of a PN junction of a SPAD element and the circuit operation of a pixel circuit using the SPAD element.

[0026] Figure 5 is a perspective view schematically showing the structure of a semiconductor chip of a light receiving device.

[0027] Figure 6 is a circuit diagram showing a configuration example of a pixel circuit including a protection circuit according to a reference example.

[0028] Figure 7 is a circuit diagram schematically showing an embodiment of the present technology.

[0029] Figure 8 : is a perspective view schematically showing the configuration of a pixel array section in a light receiving device according to a first example of an embodiment of the present technology.

[0030] Fig. 9 is a perspective view schematically showing a wiring structure of a pixel array section in the light receiving device according to the first embodiment.

[0031] Fig.10 : is a plan view schematically showing the configuration of a pixel array section in a light receiving device according to a second example in the embodiments of the present technology.

[0032] Fig.11 is a plan view schematically showing a wiring structure of a pixel array section in a light receiving device according to the second embodiment.

[0033] Fig.12 : is a perspective view schematically showing the configuration of a pixel array section in a light receiving device according to a third example in the embodiment of the present technology.

[0034] Fig.13 is an explanatory diagram of two adjacent dummy pixels in the light receiving device according to the third embodiment.

[0035] Fig.14 : is a circuit diagram schematically showing a circuit configuration example of a protection circuit of a light receiving device according to a fourth example in the embodiment of the present technology.

[0036] Fig.15 4 is a diagram for explaining an example of a configuration in which three surge current paths are formed in the light receiving device according to the fourth embodiment.

[0037] Fig.16 is a perspective view schematically showing a wiring structure of a pixel array section in a light receiving device according to a fourth embodiment.

[0038] Fig.17 : is a diagram for explaining an example of a configuration in which three surge current paths are formed in the light receiving device according to the fifth example in the embodiment of the present technology.

[0039] Fig.18 : is a circuit diagram schematically showing a circuit configuration example of a pixel circuit and a dummy pixel of a light receiving device according to a sixth example in the embodiment of the present technology.

[0040] Fig.19 : is a circuit diagram schematically showing a circuit configuration example of a pixel circuit and a dummy pixel of a light receiving device according to a seventh example in the embodiments of the present technology.

[0041] Fig. 20 is a block diagram showing a schematic configuration embodiment of a vehicle control system.

[0042] Fig.21 1 is an explanatory diagram showing an example of the installation position of the imaging section. DETAILED DESCRIPTION

[0043] Hereinafter, a mode for carrying out the present technology (hereinafter, referred to as an embodiment) will be described. The description will be given in the following order.

[0044] 1. ToF-based distance measurement system

[0045] 1-1. System Configuration Example

[0046] 1-2. Basic Configuration Example of Distance Measuring Device

[0047] 1-3. Basic pixel circuit embodiment using SPAD element

[0048] 1-4. Semiconductor chip structure of optical receiving device

[0049] 1-4-1. Stacked semiconductor chip structure

[0050] 1-4-2. Planar semiconductor chip structure

[0051] 1-5. Protection circuit according to reference example

[0052] 2. Implementation of the present technology

[0053] 2-1. First Embodiment (Embodiment of Stacked Semiconductor Chip Structure)

[0054] 2-2. Second Embodiment (Embodiment of Planar Semiconductor Chip Structure)

[0055] 2-3. Third Embodiment (Embodiment in which a SPAD element of a dummy pixel adjacent to a dummy pixel to which the SPAD element belongs is used as a diode element)

[0056] 2-4. Fourth Embodiment (Embodiment Not Required to Provide a High Withstand Voltage Protection Element in a Pixel Circuit)

[0057] 2-5. Fifth Embodiment (Modification of the Fourth Embodiment: Embodiment Using SPAD Elements of Adjacent Dummy Pixels as Diode Elements)

[0058] 2-6. Sixth Embodiment (Embodiment in which the Pixel Circuit Includes a Thin Film Transistor)

[0059] 2-7. Seventh Embodiment (Embodiment in which the polarity of the voltage applied to the SPAD element is reversed in the pixel circuit)

[0060] 3. Modification Example

[0061] 4. Application examples for mobile objects

[0062] 5. Configurations that this technology can adopt

[0063] <1. ToF-based distance measurement system>

[0064] [System Configuration Example]

[0065] Figure 1 1 is a conceptual diagram showing a system configuration embodiment of a distance measurement system based on ToF. In the distance measurement system according to the present system configuration embodiment, a distance measurement device 1 adopts a ToF method as a measurement method for measuring a distance to an object 10 as a distance measurement object, and includes a light source unit 20 and a light receiving device 30 to implement distance measurement by the ToF method.

[0066] The light source unit 20 emits light toward the object 10. An embodiment of the light emitted from the light source unit 20 toward the object 10 includes a laser having a peak wavelength in the infrared wavelength range. The light receiving device 30 includes a plurality of pixels, specifically, a plurality of pixels arranged in a matrix (array) in two dimensions, and detects (receives) reflected light reflected and returned by the object 10 in units of pixels.

[0067] [Basic Configuration Example of Distance Measuring Device]

[0068] Figure 2 A basic configuration example of a ToF-based distance measurement device 1 is shown. Figure 2 a shows the overall configuration of the distance measuring device 1, and Figure 2 b shows a configuration example on the light receiving device 30 side.

[0069] The light source unit 20 includes, for example, a laser driving unit 21, a laser light source 22, and a diffusion lens 23, and irradiates the object 10 as a distance measurement object with laser light. The laser driving unit 21 drives the laser light source 22 under the control of the control unit 40. The laser light source 22 uses, for example, a semiconductor laser as a light source, and emits pulsed laser light (hereinafter, which may be referred to as laser pulse light) under the drive of the laser driving unit 21. The diffusion lens 23 diffuses the laser pulse light emitted from the laser light source 22, and irradiates the object 10 with the laser pulse light.

[0070] The light receiving device 30 includes a light receiving lens 31, an optical sensor 32, and a signal processing unit 33, and receives the reflected laser pulse light returned after the irradiation laser pulse light emitted from the light source unit 20 is reflected by the object 10. The light receiving lens 31 gathers the reflected laser pulse light from the object 10 to the light receiving surface of the optical sensor 32. The optical sensor 32 includes a plurality of pixels, receives the reflected laser pulse light from the object 10 through the light receiving lens 31 in units of pixels, and performs photoelectric conversion. As the optical sensor 32, for example, a two-dimensional array sensor including pixels of light receiving elements arranged in a matrix (array) in two dimensions can be used.

[0071] The output signal of the optical sensor 32 is supplied to the control unit 40 via the signal processing unit 33. The control unit 40 is, for example, an application processor including a processor such as a central processing unit (CPU), controls the light source unit 20 and the light receiving device 30, and measures the time until the pulse laser emitted from the light source unit 20 toward the object 10 is reflected and returned by the object 10. The distance to the object 10 can be obtained based on the measured time.

[0072] Then, in the distance measuring device 1 in the present embodiment, the optical sensor 32 may include a sensor including an element for detecting the presence or absence of photons, for example, a single photon avalanche diode (SPAD) element as a light receiving element of a pixel. That is, the light receiving device 30 of the distance measuring device 1 illustrated here has a configuration using a SPAD element as a light receiving element of a pixel. The SPAD element operates in a so-called Geiger mode, in which the element is in a state of being ... BD Operate under reverse voltage.

[0073] It should be noted that, here, the SPAD element is exemplified as the light receiving element of the pixel, but the light receiving element is not limited to the SPAD element. That is, as the light receiving element of the pixel, various elements operating in the Geiger mode such as an avalanche photodiode (APD) and a silicon photomultiplier (SiPM) can be used in addition to the SPAD element.

[0074] [Basic pixel circuit embodiment using SPAD element]

[0075] Here, we will refer to Figure 3 and Figure 4 A basic pixel circuit in the light receiving device 30 using the SPAD element is described.

[0076] Figure 3 : is a circuit diagram showing an example of a configuration of a basic pixel circuit in the light receiving device 30 using a SPAD element. Here, a basic configuration of one pixel is shown. Figure 4a is a characteristic diagram showing the current-voltage characteristics of the PN junction of the SPAD element, and Figure 4 b is a waveform diagram for explaining the circuit operation of the pixel circuit using the SPAD element.

[0077] In a basic pixel circuit (pixel readout circuit) of a pixel 50 using a SPAD element, the cathode electrode of the SPAD element 51 is connected to a P-type MOS transistor Q L The quenching element 54 is connected to the terminal 52. The power supply voltage V DD is applied to the terminal 52. The terminal 52 is an example of a third terminal described in the claims, and the power supply voltage V DD The second power supply voltage is supplied to a readout circuit including a quenching element 54 .

[0078] The anode electrode of the SPAD element 51 is connected to the terminal 53. A predetermined voltage (specifically, a large negative voltage at which avalanche multiplication occurs) is applied as the anode voltage V ANO The anode voltage V is supplied to the terminal 53. The terminal 53 is an example of the first terminal described in the claims, and the anode voltage V ANO Applied to the anode electrode of the SPAD element 51 .

[0079] In the quenching element 54, the predetermined bias voltage V bias Applied to the P-type MOS transistor Q L The gate electrode of the bias The MOS transistor Q L Operate as the desired current source.

[0080] Then, through the P-type MOS transistor Q p and N-type MOS transistor Q N The CMOS inverter 55 derives the cathode voltage V of the SPAD element 51 CA As SPAD output (pixel output). CMOS inverter 55 can be referred to as using threshold voltage V th The comparison circuit (comparator) as a comparison reference, or it can be called a waveform shaping circuit, which uses the threshold voltage V th The cathode voltage V as the output of the SPAD element 51 is used as a reference. CA The waveform is shaped.

[0081] Equal to or higher than the breakdown voltage V BD A voltage of V is applied to the SPAD element 51. BD The excess voltage is called the excess bias voltage V EX The characteristics of the SPAD element 51 are determined by applying an excess bias voltage VEX Relative to the breakdown voltage V BD The voltage value changes.

[0082] Figure 4 FIG. 1a shows the current-voltage characteristic of the PN junction of the SPAD element 51 operating in the Geiger mode. Specifically, FIG. 1a shows the breakdown voltage V BD , Excess bias voltage V EX The relationship between φ(A) and the operating point of the SPAD element 51 .

[0083] [Example of Circuit Operation of Pixel Circuit Using SPAD Element]

[0084] Next, we will refer to Figure 4 The waveform diagram in b describes an example of the circuit operation of the pixel circuit having the above configuration.

[0085] When no current flows through the SPAD element 51, the DD -V ANO ) is applied to the SPAD element 51. The voltage value (V DD -V ANO ) is (V BD +V EX ). Then, at the PN junction of the SPAD element 51, the dark count rate (DCR) and the electrons generated by light irradiation produce avalanche multiplication, and an avalanche current is generated.

[0086] When the cathode voltage V CA The voltage between the terminals of the SPAD element 51 decreases and reaches the breakdown voltage V of the PN junction diode. BD Then, the electrons generated and accumulated by avalanche multiplication pass through the quenching element 54 (for example, a P-type MOS transistor Q L ) discharge. This discharge increases the cathode voltage V CA Then, the cathode voltage V of the SPAD element 51 CA is restored to the power supply voltage V DD , and returns to the initial state again.

[0087] When light is incident on the SPAD element 51 and even one electron-hole pair is generated, the electron-hole pair becomes a seed, and an avalanche current is generated. Therefore, even when one photon is incident, detection can be performed with a certain photon detection efficiency (PDE).

[0088] The above operation is repeated. Then, in this series of operations, the cathode voltage V CAWaveform shaping is performed by the CMOS inverter 55, and a pulse signal having a pulse width T starting from the arrival time of one photon becomes a SPAD output (pixel output).

[0089] [Semiconductor chip structure of light receiving device]

[0090] As the semiconductor chip structure of the light receiving device 30 having the above configuration, a planar semiconductor chip structure and a stacked semiconductor chip structure can be applied as embodiments. The stacked semiconductor chip structure and the planar semiconductor chip structure will be schematically described below.

[0091] Figure 5 is a perspective view schematically showing the semiconductor chip structure of the light receiving device 30 . Figure 5 a schematically shows a stacked semiconductor chip structure, and Figure 5 b schematically shows a planar semiconductor chip structure.

[0092] (Stacked semiconductor chip structure)

[0093] like Figure 5 As shown in a, the stacked semiconductor chip structure (so-called stacked structure) has a chip structure in which at least two semiconductor substrates (chips) of a first semiconductor substrate 61 and a second semiconductor substrate 62 are stacked.

[0094] In the stacked semiconductor chip structure, the first semiconductor substrate 61 is a sensor chip in which the SPAD elements 51 as an embodiment of the light receiving elements are arranged in a matrix in two dimensions. The second semiconductor substrate 62 is a logic chip in which the readout circuit (logic circuit) 50A of the pixel 50 paired with the SPAD elements 51 in the first semiconductor substrate 61 is arranged in a matrix in two dimensions corresponding to the SPAD elements 51.

[0095] The SPAD element 51 on the first semiconductor substrate 61 is electrically connected to the readout circuit (logic circuit) 50A on the second semiconductor substrate 62 via a joint portion 64 formed in a wiring layer 63 between the first semiconductor substrate 61 and the second semiconductor substrate 62. As an example of the joint portion 64 of the wiring layer 63, a Cu-Cu joint for directly joining Cu electrodes can be exemplified.

[0096] According to the stacked semiconductor chip structure described above, a process suitable for manufacturing the SPAD element 51 can be applied to the first semiconductor substrate 61, and a process suitable for manufacturing the readout circuit 50A of the pixel 50 can be applied to the second semiconductor substrate 62. That is, the process of manufacturing the light receiving device 30 can be optimized.

[0097] (Planar semiconductor chip structure)

[0098] like Figure 5 As shown in b, the planar semiconductor chip structure (i.e., planar structure) is a chip structure in which the SPAD element 51 and the readout circuit 50A of the pixel 50 are formed on the same semiconductor substrate 65. Specifically, the SPAD element 51 and the readout circuit 50A of the pixel 50 are paired and arranged in a matrix in two dimensions on the same semiconductor substrate 65.

[0099] As described above, the semiconductor chip structure of the light receiving device 30 used in the distance measuring device 1 can be a stacked semiconductor chip structure in which the PAD element 51 and the readout circuit 50A of the pixel 50 are formed and stacked on a separate semiconductor substrate; or it can be a planar semiconductor chip structure in which both are formed on the same semiconductor substrate.

[0100] [About the protection circuit according to the reference example]

[0101] Here, the state of a protection circuit that protects a readout circuit of a pixel 50 including a SPAD element 51 from an ESD surge voltage will be described as a protection circuit according to a reference example. The protection circuit according to the reference example is a protection circuit provided in a pixel circuit.

[0102] Figure 6 is a circuit diagram showing a configuration example of a pixel circuit including a protection circuit according to a reference example. Figure 6 As shown in FIG. 1 , a high withstand voltage protection element 56 for protecting a readout circuit of a pixel 50 including a SPAD element 51 from an ESD surge voltage is connected to a region supplied with a power supply voltage V on the high potential side. DD The terminal 52 is provided with an anode voltage V ANO between terminals 53.

[0103] In addition to the high withstand voltage protection element 56, a logic circuit protection circuit (RCMOS) 58 is provided to protect the logic circuit (pixel readout circuit) including the CMOS inverter 55 and the like. The logic circuit protection circuit 58 is connected to a power supply voltage V DD The terminal 52 is provided with a power supply voltage V on the low potential side SS (e.g., 0 V) ​​between terminals 57.

[0104] In addition, the N-type MOS transistor Q N The node N is connected to a power supply voltage V SS The node N is a connection node between the cathode electrode of the SPAD element 51 and the quenching element 54. The terminal 57 is an embodiment of the second terminal described in the claims, and is connected to the N-type MOS transistor Q N The logic circuit (pixel readout circuit) provides a power supply voltage V on the low potential side as the first power supply voltage.SS .

[0105] In the protection circuit according to the above-mentioned reference example, the high withstand voltage protection element 56 protects the readout circuit of the pixel 50 including the SPAD element 51 from the influence of the ESD surge voltage by releasing the ESD surge voltage entering when assembling or manufacturing the light receiving device 30. The high withstand voltage protection element 56 should not operate at a voltage equal to or lower than the normal operating voltage of the SPAD element 51, and needs to operate at a voltage higher than the normal operating voltage.

[0106] That is, when the breakdown voltage of the SPAD element 51 is V BD and the excess bias voltage is V EX When the high withstand voltage protection element 56 is used, the operation start voltage (on voltage) V ON , to meet |V ON |>|V BD +V EX Therefore, since the breakdown region is included in the normal operation of the SPAD element 51, even if current flows through the SPAD element 51, the high withstand voltage protection element 56 should not operate and does not contribute to protecting the readout circuit of the pixel 50 including the SPAD element 51.

[0107] Therefore, the high withstand voltage protection element 56 is used as a protection element to prevent the ESD surge voltage entering from the terminal 53 (i.e., the forward ESD surge voltage of the SPAD element 51), but is not used as a protection element to prevent the ESD surge voltage entering from the terminal 52 (i.e., the reverse ESD surge voltage of the SPAD element 51).

[0108] Therefore, the protection circuit according to the reference example has the following configuration: Figure 6 The thick dashed line in FIG. 5 indicates the surge current path 59, that is, terminal 52 → N-type MOS transistor Q N A current path of parasitic diode →SPAD element 51 →terminal 53 is established, and the surge current flows through the SPAD element 51 itself, thereby protecting the readout circuit of the pixel 50 including the SPAD element 51 from the reverse ESD surge voltage of the SPAD element 51.

[0109] As mentioned above, in Figure 6 The surge current path 59 indicated by the thick dashed line is integrated into the N-type MOS transistor Q N Then, the surge current path 59 is formed by the N-type MOS transistor Q N and the smaller allowable current I of the SPAD element 51 最大值 To determine the current capacity per pixel.

[0110] It should be noted that although Figure 6 The pixel circuit of one pixel is shown, but a plurality of pixels (a plurality of systems) are actually connected in parallel. Then, even if the SPAD element 51 and the N-type MOS transistor Q forming the surge current path 59 N The breakdown voltage V BD In the embodiment of the present invention, the plurality of pixels (multiple systems) are also operated in parallel in the instantaneous charge transfer during the ESD event. That is, the charge that can flow into one system is limited due to the high impedance, and each system is turned on in turn and operated in parallel. Therefore, the ESD surge current flowing through the surge current path 59 is shunted among a large number of pixels.

[0111] As described above, the protection circuit according to the reference example has a configuration in which the surge current path 59 exists in the pixel circuit. Here, the problem of the recent miniaturization of the SPAD element 51 is the size of the pixel circuit (logic circuit) paired with the SPAD element 51, and how small the size can be is an urgent issue. In the future, the transition to the micro-manufacturing process of the logic circuit is an inevitable trend, and it is expected that the allowable current I of the surge current path 59 will be 最大值 That is, when a surge current path 59 exists in a pixel circuit, the amount of current flowing through the surge current path 59 (i.e., the amount of current required for ESD surge protection) depends on the circuit configuration, size, etc. of the pixel circuit.

[0112] <2. Embodiments of the present technology>

[0113] Figure 7 Schematically shows a circuit diagram of an embodiment of the present technology. In the embodiment of the present technology, for example, in a light receiving device 30 using a SPAD element as a light receiving element of a pixel, in order to ensure the amount of current required for ESD surge protection without depending on the circuit configuration, size, etc. of the pixel circuit, the following dummy pixel is used, and a surge current path (current path) for causing the ESD surge current to flow is formed in the dummy pixel using the light receiving element of the dummy pixel.

[0114] The pixel array section in the light receiving device 30 includes an effective pixel region 100 and a dummy pixel region 200. In the effective pixel region 100, effective pixels 101 that contribute to detecting the presence or absence of photons (i.e., contribute to measuring the flight time of light) are arranged in a matrix. In the dummy pixel region 200, dummy pixels 201 that do not contribute to detecting the presence or absence of photons (i.e., do not contribute to measuring the flight time of light) are arranged in a matrix.

[0115] As an embodiment of the second light receiving element described in the claims, similarly to the light receiving element of the effective pixel 101 as an embodiment of the first light receiving element described in the claims, the SPAD element 202 can also be used as a light receiving element of the dummy pixel 201. In the dummy pixel region 200, the dummy pixel 201 is supplied with an anode voltage V ANO Terminal 53 or a low potential side power supply voltage V SS Terminal 57 is arranged with low impedance.

[0116] In the embodiment of the present technology, by using the SPAD element 202 as the light receiving element of the dummy pixel 201 and connecting the diode element 203 in series to the SPAD element 202, a surge current path 204 (by the diode 203) for causing the ESD surge current to flow is formed in the dummy pixel 201. Figure 7 The dashed (bold) arrow in the figure shows the arrowhead.

[0117] Specifically, in the dummy pixel 201, the SPAD element 202 and the diode element 203 are connected in series in a polarity relationship opposite to each other, as a diode to which an anode voltage V ANO The first terminal 53 is connected to the power supply voltage V of the low potential side. SS The surge current path 204 is formed between the terminal 57 and the second terminal of the SPAD element 202. That is, the anode electrode of the SPAD element 202 is connected to the terminal 53, the cathode electrode of the SPAD element 202 and the diode element 203 are commonly connected, and the anode electrode of the diode element 203 is connected to the terminal 57.

[0118] Here, the SPAD element 202 and the diode element 203 of the dummy pixel 201 forming the surge current path 204 constitute a protection circuit that protects the SPAD element 51 of the effective pixel 101 and the circuit elements of the readout circuit of the effective pixel 101 from overvoltage, specifically, the reverse ESD surge voltage of the SPAD element 51. In addition to a general diode, a diode-connected transistor or the like can be exemplified as the diode element 203.

[0119] As described above, in the embodiment of the present technology, the dummy pixel 201 existing outside the effective pixel region 100 is utilized, and the surge current path 204 is formed in the dummy pixel 201 using the SPAD element 202 of the dummy pixel 201. Therefore, it is possible to ensure the amount of current required for ESD surge protection without depending on the circuit configuration, size, etc. of the pixel circuit of the effective pixel 101 (specifically, the readout circuit of the effective pixel 101).

[0120] Here, the reason why the surge current path 204 of the dummy pixel 201 does not operate during the normal operation of each effective pixel 101 in the effective pixel area 100 will be described.

[0121] The SPAD element has a temperature characteristic. By variably controlling the anode voltage V applied to the terminal 53 according to the temperature along the temperature characteristic of the SPAD element, ANO , ensuring that the anode voltage V ANO Withstand voltage between the logic circuit (pixel readout circuit).

[0122] Assuming the breakdown voltage of the SPAD element is V BD is 20V, in normal operation, V SS -V ANO On the other hand, when the forward voltage of the diode is V f When the surge current path 59 in the effective pixel 101 and the surge current path 204 in the dummy pixel 201 have a withstand voltage of about 20+V f As described above, since the withstand voltage of each of the surge current paths 59 and 204 is greater than V SS -V ANO The surge current path 204 of the dummy pixel 201 does not operate during the normal operation of the effective pixel 101.

[0123] For the above reasons, when the surge current path 204 is formed in the dummy pixel 201 using the SPAD element 202 of the dummy pixel 201 , it is necessary to connect the diode element 203 in series to the SPAD element 202 .

[0124] According to the protection circuit of the embodiment of the present technology, even if the breakdown voltage V BD Existence changes

[0125] , when instantaneously observed as described above, the surge current path 204 of the dummy pixel 201 also operates in parallel. Therefore, there is no problem even if the surge current path 59 in the effective pixel 101 is turned on, and the total amount of current combined with the surge current path 204 of the dummy pixel 201 can be considered. In fact, it is preferable to ensure the amount that meets the standard only by the amount of current of the surge current path 204 of the dummy pixel 201.

[0126] Hereinafter, a specific embodiment of an implementation of the present technology will be described, which is used to ensure the amount of current required for ESD surge protection by forming a surge current path 204 using a SPAD element 202 of a pseudo pixel 201 without depending on the circuit configuration, size, etc. of the pixel circuit of the effective pixel 101.

[0127] [First embodiment]

[0128] The first example of the embodiment of the present technology is an example in which the semiconductor chip structure of the light receiving device 30 is a stacked semiconductor chip structure. Figure 8 is a perspective view schematically showing the configuration of a pixel array section in a light receiving device 30 according to a first example in an embodiment of the present technology, and Fig. 9 : is a perspective view schematically showing a wiring structure of a pixel array section in the light receiving device 30 according to the first embodiment.

[0129] like Figure 8 and Fig. 9 As shown, the pixel array section of the light receiving device 30 according to the first embodiment includes an effective pixel region 100 where effective pixels 101 are arranged in a matrix, and a dummy pixel region 200 where dummy pixels 201 are arranged in a matrix in a stacked semiconductor chip structure.

[0130] In the stacked semiconductor chip structure, in the effective pixel region 100, the SPAD element 51 is formed on the first semiconductor substrate 61 (see Figure 5 a), and the readout circuit (logic circuit) 50A of the effective pixel 101 paired with the SPAD element 51 is formed on the second semiconductor substrate 62 with the same size as the formation area of ​​the SPAD element 51 (see Figure 5 a) in the figure.

[0131] Similarly, in the dummy pixel region 200, a SPAD element 202 is formed on the first semiconductor substrate 61, and a circuit formation region 201A paired with the SPAD element 202 is formed on the second semiconductor substrate 62 with the same size as the formation region of the SPAD element 202. Typically, in the circuit formation region 201A of the dummy pixel 201, a logic circuit similar to the readout circuit 50A of the effective pixel 101 is formed, but it may not be formed.

[0132] In the above-mentioned stacked semiconductor chip structure, in the light receiving device 30 according to the first embodiment, when the surge current path 204 is formed using the SPAD element 202 of the pseudo pixel 201, the diode element 203 connected in series to the SPAD element 202 is formed in the circuit forming area 201A paired with the SPAD element 202 by changing to a logic circuit similar to the readout circuit 50A of the effective pixel 101.

[0133] In the stacked semiconductor chip structure, the circuit formation region 201A paired with the SPAD element 202 corresponds to the circuit formation region paired with the SPAD element 51, that is, the region in which the readout circuit (logic circuit) 50A of the effective pixel 101 paired with the SPAD element 51 is formed, and has a size similar to that of the circuit formation region of the readout circuit 50A. In this way, the diode element 203 is formed as a single circuit element in the circuit formation region 201A, the size of which is similar to that of the circuit formation region of the readout circuit 50A of the effective pixel 101.

[0134] Therefore, the diode element 203 can be formed to have an extremely large size compared to the case where a diode is formed as a single circuit element in the readout circuit 50A of the effective pixel 101. Then, since the size of the diode element 203 can be increased, the allowable current of the pair of SPAD elements 202 and the diode element 203 can be set large, making it possible to ensure a larger amount of current as the amount of current required for ESD surge protection flowing through the surge current path 204.

[0135] like Fig. 9 As shown, an anode voltage V is applied ANO The terminal 53 of the effective pixel 101 is electrically connected to each anode electrode of the SPAD element 51 and each anode electrode of the SPAD element 202 of the dummy pixel 201 through the wiring 65. In addition, a power supply voltage V SS The terminal 57 of the effective pixel 101 is connected to the N-type MOS transistor Q in the readout circuit (logic circuit) 50A of the effective pixel 101. N The anode electrode of each diode element 203 of the dummy pixel 201 is electrically connected via the wiring 66 .

[0136] As described above, in the light receiving device 30 according to the first embodiment, in the stacked semiconductor chip structure, the diode element 203 connected in series to the SPAD element 202 of the dummy pixel 201 to form the surge current path 204 is formed as a diode element having a large size in the circuit formation region 201A below the SPAD element 202. Therefore, a larger amount of current can be ensured as the amount of current required for ESD surge protection flowing through the surge current path 204.

[0137] [Second embodiment]

[0138] The second example of the embodiment of the present technology is an example in which the semiconductor chip structure of the light receiving device 30 is a planar semiconductor chip structure. Fig.10 is a plan view schematically showing a configuration of a pixel array section in a light receiving device 30 according to a second embodiment in an embodiment of the present technology, and Fig.11: is a plan view schematically showing a wiring structure of a pixel array section in a light receiving device 30 according to the second embodiment.

[0139] like Fig.10 and Fig.11 As shown, the pixel array section of the light receiving device 30 according to the second embodiment includes an effective pixel region 100 where effective pixels 101 are arranged in a matrix, and a dummy pixel region 200 where dummy pixels 201 are arranged in a matrix in a planar semiconductor chip structure.

[0140] In the planar semiconductor chip structure, in the effective pixel region 100, the readout circuit (logic circuit) 50A of the effective pixel 101 paired with the SPAD element 51 is arranged adjacent to the formation region with a size similar to that of the formation region of the SPAD element 51. Similarly, in the dummy pixel region 200, the circuit formation region 201A paired with the SPAD element 202 is arranged adjacent to the formation region with a size similar to that of the formation region of the SPAD element 202. Typically, in the circuit formation region 201A of the dummy pixel 201, a logic circuit similar to the readout circuit 50A of the effective pixel 101 is formed, but it may not be formed.

[0141] In the above-mentioned planar semiconductor chip structure, in the light receiving device 30 according to the second embodiment, when the surge current path 204 is formed using the SPAD element 202 of the pseudo pixel 201, the diode element 203 connected in series to the SPAD element 202 is formed in the circuit forming area 201A paired with the SPAD element 202 by changing to a logic circuit similar to the readout circuit 50A of the effective pixel 101.

[0142] In the planar semiconductor chip structure, the circuit formation region 201A paired with the SPAD element 202 corresponds to the circuit formation region of the readout circuit (logic circuit) 50A of the effective pixel 101 paired with the SPAD element 51, and has a size similar to that of the circuit formation region. In this way, the diode element 203 is formed as a single circuit element in the circuit formation region 201A having a size similar to that of the circuit formation region of the readout circuit 50A of the effective pixel 101.

[0143] Therefore, compared with the case where a diode is formed as a single circuit element in the readout circuit 50A of the effective pixel 101, the diode element 203 can be formed to have an extremely large size. Then, since the size of the diode element 203 can be set large, a larger amount of current can be ensured as the amount of current required for ESD surge protection flowing in the surge current path 204 formed using the diode element 203.

[0144] like Fig.11As shown, an anode voltage V is applied ANO The terminal 53 of the effective pixel 101 is electrically connected to each anode electrode of the SPAD element 51 and each anode electrode of the SPAD element 202 of the dummy pixel 201 through the wiring 65. In addition, a power supply voltage V SS The terminal 57 of the effective pixel 101 is connected to the N-type MOS transistor Q in the readout circuit (logic circuit) 50A of the effective pixel 101. N The anode electrode of each diode element 203 of the dummy pixel 201 is electrically connected via the wiring 66 .

[0145] As described above, in the light receiving device 30 according to the second embodiment, in the planar semiconductor chip structure, the diode element 203 connected in series to the SPAD element 202 of the dummy pixel 201 to form the surge current path 204 is formed as a diode element having a large size in the circuit formation region 201A paired with the SPAD element 202. Therefore, a larger amount of current can be ensured as the amount of current required for ESD surge protection flowing through the surge current path 204.

[0146] [Third embodiment]

[0147] A third example of an embodiment of the present technology is an example in which a SPAD element of a dummy pixel adjacent to the dummy pixel to which the SPAD element belongs is used as the diode element forming the surge current path. Fig.12 : is a perspective view schematically showing the configuration of a pixel array section in a light receiving device 30 according to a third example in the embodiment of the present technology.

[0148] Here, under the premise of a stacked semiconductor chip structure, a case where the SPAD element of an adjacent dummy pixel is used as the diode element 203 forming the surge current path 204 will be described as an embodiment of the light receiving device 30 according to the third embodiment. However, the present invention is not limited to the stacked semiconductor chip structure, and a similar configuration can also be adopted in a planar semiconductor chip structure.

[0149] In the dummy pixel 201 , for a circuit formation region 201A paired with the SPAD element 202 , a logic circuit similar to the readout circuit (logic circuit) 50A of the effective pixel 101 may or may not be formed. Fig.12 The case where a logic circuit similar to the readout circuit 50A of the effective pixel 101 is not formed in the circuit formation region 201A is shown.

[0150] Here, two dummy pixels 201 and 201 adjacent in the row direction of the pixel array in the matrix are paired to form the surge current path 204 , but the present invention is not limited thereto, and two dummy pixels 201 and 201 adjacent in the column direction may be paired to form the surge current path 204 .

[0151] Fig.13 is an explanatory diagram of two adjacent dummy pixels in the light receiving device 30 according to the third embodiment. Fig.13 a is a planar graph of two pseudo pixels, and Fig.13 b is a cross-sectional view of two pseudo pixels.

[0152] In the corresponding SPAD elements 202 and 202 of the two dummy pixels 201 and 201 adjacent in the row direction, the corresponding anode electrodes are connected to the terminals 53 and 57 via the wirings 67_1 and 67_2 of the wiring layer 67 (see Figure 7 ). In addition, the cathode electrodes of the two SPAD elements 202 and 202 are electrically connected through the wiring 68. With this connection structure, the two SPAD elements 202 and 202 have Figure 7 The electrical connection relationship shown in , and one of them becomes the diode element 203.

[0153] As described above, in the light receiving device 30 according to the third embodiment, as the diode element 203 connected in series to the SPAD element 202 of the dummy pixel 201 to form the surge current path 204, the SPAD element 202 of the dummy pixel 201 adjacent to the dummy pixel to which the light receiving device belongs is used. Therefore, there is no need to newly form the diode element 203 as in the first and second embodiments, and a desired surge current path 204 can be formed and the amount of current required for ESD surge protection can be ensured only by adding the wiring 67 or changing the circuit formation region 201A.

[0154] [Fourth embodiment]

[0155] In the optical receiving device 30 according to the first to third embodiments described above, it is assumed that Figure 6 The protection circuit of the reference example shown in FIG. 1 , that is, a protection circuit including a high withstand voltage protection element 56 and a logic circuit protection circuit 58 is provided in the pixel circuit, but this is not necessary. That is, although the logic circuit protection circuit 58 cannot be omitted, in the protection circuit of the SPAD element 202 using the pseudo pixel 201, the high withstand voltage protection element 56 can be made unnecessary by designing the circuit configuration.

[0156] The fourth example of the embodiment of the present technology is an example in which the high withstand voltage protection element 56 does not necessarily need to be provided in the pixel circuit. Fig.14 : is a circuit diagram schematically showing a circuit configuration example of a protection circuit of the light receiving device 30 according to the fourth example in the embodiment of the present technology.

[0157] like Fig.14As shown, in addition to the diode element 203 connected in series with the SPAD element 202 in a reverse polarity relationship, the protection circuit in the optical receiving device 30 according to the fourth embodiment has a configuration including two diode elements 205 and 206, which is formed using two dummy pixels 201 and 201 adjacent to the dummy pixel 201 including the SPAD element 202.

[0158] The diode element 203 is connected between the cathode electrode of the SPAD element 202 of the dummy pixel 201 to which the diode element belongs and the power supply voltage V SS The terminals 57 of the SPAD element 202 are connected in series with each other in a reverse polarity relationship, thereby forming a surge current path 204 (by Fig.14 As described above, the surge current path 204 protects the SPAD element 51 of the effective pixel 101 and the circuit elements of the readout circuit of the effective pixel 101 from the reverse ESD surge voltage of the SPAD element 51 .

[0159] The diode element 205 is connected between the cathode electrode of the SPAD element 202 of the dummy pixel 201 to which the diode element belongs and the power supply voltage V SS The terminal 57 is connected in series with the SPAD element 202 in a positive polarity relationship, thereby forming a surge current path 207 (by Fig.14 The surge current path 207 protects the SPAD element 51 of the effective pixel 101 and the circuit elements of the readout circuit of the effective pixel 101 from the influence of the forward ESD surge voltage of the SPAD element 51 .

[0160] The diode element 206 is connected between the cathode electrode of the SPAD element 202 of the dummy pixel 201 to which the diode element belongs and the power supply voltage V DD The terminal 52 is connected in series with the SPAD element 202 in a positive polarity relationship, thereby forming a surge current path 208 (by Fig.14 The surge current path 208 protects the SPAD element 51 of the effective pixel 101 and the circuit elements of the readout circuit of the effective pixel 101 from the influence of the forward ESD surge voltage of the SPAD element 51 .

[0161] As described above, three surge current paths, ie, the surge current path 204 , the surge current path 207 , and the surge current path 208 may be formed using three dummy pixels adjacent to each other as one group.

[0162] Fig.15An example of a configuration in which three surge current paths 204 , 207 , and 208 are formed as a group of three dummy pixels adjacent to each other in the light receiving device 30 according to the fourth embodiment is shown. Fig.15 A certain group of three dummy pixels is shown in the dummy pixel region 200. Here, the case of a stacked semiconductor chip structure is exemplified, but the present invention is not limited to the stacked semiconductor chip structure. Fig.15 a is a stereogram of three pseudo pixels, and Fig.15 b is a plan view of three pseudo pixels.

[0163] As in the case of the first embodiment, the diode element 203 connected in series with the SPAD element 202 of the pseudo pixel 201 in a reverse polarity relationship to form a surge current path 204 is formed as a single circuit element in the circuit forming area 201A paired with the SPAD element 202, that is, formed as a large-sized diode element.

[0164] The diode elements 205 and 206 connected in series with the SPAD element 202 of the dummy pixel 201 in a forward polarity relationship to form surge current paths 207 and 208 are respectively formed as logic diode elements in the circuit formation regions 201A and 201A located below the element regions in the other two dummy pixels 201 and 201. The electrical connection relationship of the diode elements 205 and 206 is as follows: Fig.14 shown.

[0165] Fig.16 The wiring structure of the pixel array section in the light receiving device 30 according to the fourth embodiment is schematically shown.

[0166] As described above, in addition to the surge current path 204 including the diode element 203 connected in series with the SPAD element 202 in a reverse polarity relationship, the light receiving device 30 according to the fourth embodiment further includes two surge current paths 207 and 208. The two surge current paths 207 and 208 include the SPAD elements 202 and 202 belonging to the pseudo pixels 201 and 201 to which the two surge current paths belong, and the diode elements 205 and 206 connected in series with the SPAD elements 202 and 202 in a forward polarity relationship.

[0167] Since the two surge current paths 207 and 208 can protect the SPAD element 51 of the effective pixel 101 and the circuit elements of the readout circuit of the effective pixel 101 from the influence of the forward ESD surge voltage of the SPAD element 51, there is no need to use the protection circuit according to the reference example (see Figure 6) uses a high withstand voltage protection element 56. Then, the high withstand voltage protection element 56 is a circuit element provided for a plurality of effective pixels 101, and since the high withstand voltage protection element 56 can be omitted, the area occupied by the high withstand voltage protection element 56 on the chip is not required, and cost reduction caused by not requiring a mask in the high withstand voltage process step can be achieved. In addition, in the light receiving device 30 according to the fourth embodiment, it is of course possible to ensure the amount of current required for ESD surge protection through the action of the surge current path 204.

[0168] It should be noted that in the fourth embodiment, the configuration in which two surge current paths of the surge current paths 207 and 208 are provided at the same time has been described as an embodiment. However, even if a configuration in which one of the surge current paths 207 and 208 is provided is adopted, the SPAD element 51 of the effective pixel 101 and the circuit elements of the readout circuit of the effective pixel 101 can be protected from the positive ESD surge voltage of the SPAD element 51.

[0169] [Fifth embodiment]

[0170] The fifth example of the embodiment of the present technology is a modification of the fourth example, and is an example of using a SPAD element of an adjacent dummy pixel as a diode element forming a surge current path when the high withstand voltage protection element 56 provided in the pixel circuit is not required.

[0171] The circuit configuration example of the protection circuit of the optical receiving device 30 according to the fifth example of the embodiment of the present technology is similar to the circuit configuration example schematically showing the circuit configuration example of the protection circuit of the optical receiving device 30 according to the fourth example. Fig.14 The circuit diagram is the same.

[0172] Specifically, the diode element 203 is connected between the cathode electrode of the SPAD element 202 of the dummy pixel 201 to which the diode element belongs and the power supply voltage V SS The terminals 57 of the SPAD element 202 are connected in series with each other in a reverse polarity relationship, thereby forming a surge current path 204 (by Fig.14 The dashed (bold) arrow in the figure shows the arrowhead.

[0173] The diode element 205 is connected between the cathode electrode of the SPAD element 202 of the dummy pixel 201 to which the diode element belongs and the power supply voltage V SS The terminal 57 is connected in series with the SPAD element 202 in a positive polarity relationship, thereby forming a surge current path 207 (by Fig.14 The solid line (bold line) and arrow in the figure are shown).

[0174] The diode element 206 is connected between the cathode electrode of the SPAD element 202 of the dummy pixel 201 to which the diode element belongs and the power supply voltage V DD The terminal 52 is connected in series with the SPAD element 202 in a positive polarity relationship, thereby forming a surge current path 208 (by Fig.14 The dashed (bold) arrow in the figure shows the arrowhead.

[0175] In the fourth embodiment, the diode elements 203, 205, and 206 forming the surge current paths 204, 207, and 208 are formed in a circuit formation region paired with the SPAD element in each dummy pixel using three dummy pixels adjacent to each other as a group. On the other hand, in the fifth embodiment, similarly to the case of the third embodiment, the SPAD elements of adjacent dummy pixels are used as the diode elements 203, 205, and 206 forming the surge current paths 204, 207, and 208. In this case, six dummy pixels adjacent to each other are regarded as a group.

[0176] Fig.17 An example of a configuration in which three surge current paths 204 , 207 , and 208 are formed as a group of six dummy pixels adjacent to each other in the light receiving device 30 according to the fifth embodiment is shown. Fig.17 There is shown one group of six dummy pixels in the dummy pixel region 200. Here, the case of a stacked semiconductor chip structure is exemplified, but the present invention is not limited to the stacked semiconductor chip structure. Fig.17 a is a stereogram of three pseudo pixels, and Fig.17 b is a plan view of three pseudo pixels.

[0177] like Fig.17 As shown in a and b of FIG. 1 , for six dummy pixels in a group, three pairs of two adjacent dummy pixels 201 and 201 are arranged as a pair on two adjacent rows. For these three pairs, the surge current paths 204, 207 and 208 are shown. Fig.14 Compared to the circuit diagram of , the pair at the upper left of the figure forms a surge current path 207 , the pair at the upper right of the figure forms a surge current path 208 , and the pair at the lower left of the figure forms a surge current path 204 .

[0178] For a group of six dummy pixels, three pairs of two adjacent dummy pixels 201 and 201 are set as a pair on two adjacent rows, thereby generating a blank area 210 corresponding to a pair at the lower right of the drawing. The blank area 210 can be formed by, for example, duplicating a power supply voltage V connected to a high potential side. DD The pair of terminals 52 at the upper right of the drawing are filled.

[0179] As described above, in the light receiving device 30 according to the fifth embodiment, in order to eliminate the need for the high withstand voltage protection element 56 provided in the pixel circuit, the SPAD elements of the adjacent dummy pixels are used as the diode elements 203, 205, and 206 that form the surge current paths 204, 207, and 208. Therefore, while eliminating the need for the high withstand voltage protection element 56, the surge current paths 204, 207, and 208 can be formed by simply adding the wiring 67 or changing the circuit formation region 201A, and the amount of current required for ESD surge protection can be ensured.

[0180] [Sixth embodiment]

[0181] The sixth example of the embodiment of the present technology is an example in which the pixel circuit includes a thin film transistor. By forming a pixel circuit (ie, a logic circuit) using a thin film transistor having a gate oxide film, the area of ​​the pixel circuit can be reduced. Fig.18 : is a circuit diagram schematically showing a circuit configuration example of a pixel circuit and a dummy pixel of a light receiving device 30 according to a sixth example in the embodiment of the present technology.

[0182] In the case where the readout circuit (pixel circuit) of the pixel 50 includes a thin film transistor, two power supply systems on the low potential side are provided. Specifically, in addition to the power supply voltage V supplied to the terminal 57, SS In addition, the power supply voltage V supplied to terminal 57A is used SS_A .

[0183] As an example, at the power supply voltage V SS When set to 0V, the negative voltage value is set to the power supply voltage V SS_A Therefore, the anode voltage V supplied to the terminal 53 ANO Set to a voltage lower than the unused power supply voltage V SS_A Negative voltage value when low power supply voltage V SS_A Similarly, the power supply voltage V DD Also set to be higher than the unused power supply voltage V SS_A Positive voltage value when low power supply voltage V SS_A The voltage value of the voltage value.

[0184] In addition, in a pixel circuit including a thin film transistor, as a protection circuit, in addition to the high-voltage protection element 56 connected between the terminal 52 and the terminal 53 and the logic circuit protection circuit 58 connected between the terminal 52 and the terminal 57, a logic circuit protection circuit 58A connected between the terminal 57 and the terminal 57A is also provided.

[0185] Also in the light receiving device 30 configuring the pixel circuit using the thin film transistor, by using the SPAD element 202 of the dummy pixel 201 and connecting the diode element 203 in series to the SPAD element 202, a surge current path 204 (by the diode 203) for causing the ESD surge current to flow is formed in the dummy pixel 201. Fig.18 The dashed (bold) arrow in the figure shows the arrowhead.

[0186] exist Fig.18 In the figure, the surge current path 204 indicated by the dotted (bold) arrow is used to protect the SPAD element 51 of the effective pixel 101 and the circuit elements of the readout circuit of the effective pixel 101 from the reverse ESD surge voltage of the SPAD element 51. In order to protect the SPAD element 51 from the forward ESD surge voltage, the surge current path 209 including the high withstand voltage protection element 56 indicated by the solid (bold) arrow plays a role.

[0187] As described above, in the light receiving device 30 according to the sixth embodiment, even in the light receiving device 30 in which the pixel circuit is configured using a thin film transistor, by forming the surge current path 204 using the dummy pixel 201, the amount of current required for ESD surge protection flowing in the surge current path 204 can be ensured.

[0188] [Seventh embodiment]

[0189] The seventh example of the embodiment of the present technology is an example in which the polarity of the voltage applied to the SPAD element is inverted in the pixel circuit. Fig.19 : is a circuit diagram schematically showing a circuit configuration example of a pixel circuit and a dummy pixel of a light receiving device 30 according to a seventh example in the embodiment of the present technology.

[0190] In the light receiving device 30 according to the first to sixth embodiments, a large negative voltage is applied to the SPAD element 51 as an anode voltage. On the other hand, in the light receiving device 30 according to the seventh embodiment, a large positive voltage is applied to the SPAD element 51 as a cathode voltage. Accordingly, the conductivity type of each transistor constituting the pixel circuit is an opposite conductivity type (P type → N type, N type → P type). The pixel circuit having this circuit configuration is a so-called anode readout type pixel circuit.

[0191] exist Fig.19In the circuit diagram of FIG. 1 , the surge current path 204 indicated by the dashed (bold) arrow is a path for protecting the SPAD element 51 of the effective pixel 101 and the circuit elements of the readout circuit of the effective pixel 101 from the reverse ESD surge voltage of the SPAD element 51. In addition, the surge current path 209 including the high withstand voltage protection element 56 indicated by the solid (bold) arrow is a path for protecting the SPAD element 51 from the forward ESD surge voltage.

[0192] As described above, in the optical receiving device 30 according to the seventh embodiment, even in the optical receiving device 30 having an anode readout type pixel circuit in which a large positive voltage is applied as a cathode voltage to the SPAD element 51, by utilizing the pseudo pixel 201, the amount of current required for ESD surge protection flowing in the surge current path 204 can be ensured.

[0193] <3. Modifications>

[0194] It should be noted that the above-mentioned embodiments show examples for embodying the present technology, and the matters in the embodiments and the matters defining the present invention in the claims have a corresponding relationship, respectively. Similarly, the matters defining the present invention in the claims have a corresponding relationship with the matters with the same names in the embodiments of the present technology. However, the present technology is not limited to the embodiments, and can be embodied by making various modifications to the embodiments without departing from the scope thereof.

[0195] <4. Application Example for Mobile Object>

[0196] The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure can be implemented in the form of a device installed on any type of mobile body (such as a car, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, and a robot).

[0197] Fig. 20 is a block diagram depicting an example of a schematic configuration of a vehicle control system as an example of a moving body control system to which the technology according to the embodiment of the present disclosure can be applied.

[0198] The vehicle control system 12000 includes a plurality of electronic control units connected to each other via a communication network 12001. Fig. 20In the illustrated embodiment, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an external information detection unit 12030, an internal information detection unit 12040, and an integrated control unit 12050. In addition, as a functional configuration of the integrated control unit 12050, a microcomputer 12051, a sound / image output unit 12052, and an in-vehicle network interface (I / F) 12053 are illustrated.

[0199] The drive system control unit 12010 controls the operation of devices related to the drive system of the vehicle according to various programs. For example, the drive system control unit 12010 is used as a control device for: a drive force generating device (such as an internal combustion engine, a drive motor, etc.) for generating a vehicle drive force, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, a braking device for generating a vehicle braking force, etc.

[0200] The body system control unit 12020 controls the operation of various devices provided to the body according to various programs. For example, the body system control unit 12020 is used as a control device for a keyless entry system, a smart key system, a power window device, or various lights such as a headlight, a backup light, a brake light, a turn signal, a fog light, etc. In this case, a radio wave transmitted from a mobile device as a substitute for a key or a signal of various switches may be input to the body system control unit 12020. The body system control unit 12020 receives these input radio waves or signals, and controls the door lock device, the power window device, the lights, etc. of the vehicle.

[0201] The vehicle exterior information detection unit 12030 detects information outside the vehicle including the vehicle control system 12000. For example, the vehicle exterior information detection unit 12030 is connected to the imaging unit 12031. The vehicle exterior information detection unit 12030 causes the imaging unit 12031 to image the image outside the vehicle and receives the imaged image. Based on the received image, the vehicle exterior information detection unit 12030 can perform a process of detecting an object such as a person, a vehicle, an obstacle, a sign, text on the road surface, etc., or a process of detecting the distance of the object.

[0202] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 may output the electrical signal as an image, or may output the electrical signal as information about the measured distance. In addition, the light received by the imaging unit 12031 may be visible light, or may be invisible light such as infrared rays.

[0203] The in-vehicle information detection unit 12040 detects information about the interior of the vehicle. For example, the in-vehicle information detection unit 12040 is connected to a driver state detection unit 12041 that detects the state of the driver. The driver state detection unit 12041 includes, for example, a camera that images the driver. The in-vehicle information detection unit 12040 can calculate the driver's fatigue or the driver's concentration based on the detection information input from the driver state detection unit 12041, or can determine whether the driver is dozing off.

[0204] The microcomputer 12051 may calculate a control target value for a driving force generating device, a steering mechanism, or a braking device based on information about the interior or exterior of the vehicle obtained by the exterior information detecting unit 12030 or the interior information detecting unit 12040, and output a control command to the drive system control unit 12010. For example, the microcomputer 12051 may perform cooperative control aimed at realizing functions of an advanced driver assistance system (ADAS), including collision avoidance or shock absorption for the vehicle, follow-up driving based on a following distance, vehicle speed maintenance driving, warning of a vehicle collision, warning of a vehicle deviation from a lane, and the like.

[0205] In addition, the microcomputer 12051 can control the driving force generating device, steering mechanism, braking device, etc. based on the information about the inside or outside of the vehicle obtained by the outside information detection unit 12030 or the inside information detection unit 12040, and perform collaborative control intended for automatic driving so that the vehicle can travel automatically without relying on the driver's operation.

[0206] In addition, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information about the exterior of the vehicle acquired by the exterior information detection unit 12030. For example, the microcomputer 12051 can perform cooperative control for preventing glare by controlling the headlights to change from high beam to low beam according to the position of the preceding vehicle or the oncoming vehicle detected by the exterior information detection unit 12030.

[0207] The sound / image output unit 12052 sends an output signal of at least one of sound and image to an output device, which can visually or auditorily notify the occupants of the vehicle or the outside of the vehicle of information. Fig. 20 In the embodiment of the present invention, the audio speaker 12061, the display portion 12062 and the instrument panel 12063 are illustrated as output devices. For example, the display portion 12062 may include at least one of an on-board display and a head-up display.

[0208] Fig.21 is a diagram illustrating an embodiment of the installation position of the imaging unit 12031.

[0209] exist Fig.21 In the figure, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104 and 12105.

[0210] The imaging units 12101, 12102, 12103, 12104 and 12105 are provided, for example, to the front nose, side mirrors, rear bumper and rear door of the vehicle 12100 and the upper part of the windshield inside the vehicle. The imaging unit 12101 provided to the front nose and the imaging unit 12105 provided to the upper part of the windshield inside the vehicle mainly obtain images in front of the vehicle 12100. The imaging units 12102 and 12103 provided to the side mirrors mainly obtain images on the sides of the vehicle 12100. The imaging unit 12104 provided to the rear bumper or rear door mainly obtains images at the rear of the vehicle 12100. The imaging unit 12105 provided to the upper part of the windshield inside the vehicle is mainly used to detect vehicles ahead, pedestrians, obstacles, signals, traffic signs, lanes, etc.

[0211] It should be noted that Fig.21 An embodiment of the shooting range of the imaging units 12101 to 12104 is depicted. The imaging range 12111 represents the imaging range of the imaging unit 12101 set to the front nose. The imaging ranges 12112 and 12113 respectively represent the imaging ranges of the imaging units 12102 and 12103 set to the side mirrors. The imaging range 12114 represents the imaging range of the imaging unit 12104 set to the rear bumper or the rear door. For example, a bird's-eye view image of the vehicle 12100 viewed from above is obtained by superimposing the image data imaged by the imaging units 12101 to 12104.

[0212] 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 composed of a plurality of imaging elements, or may be an imaging element having pixels for phase difference detection.

[0213] For example, the microcomputer 12051 can determine the distance to each three-dimensional object within the imaging range 12111 to 12114 and the time change of the distance (relative speed relative to the vehicle 12100) based on the distance information obtained from the imaging units 12101 to 12104, and thereby extract the nearest three-dimensional object that is particularly present on the driving path of the vehicle 12100 and travels in the same direction as the vehicle 12100 at a predetermined speed (e.g., equal to or greater than 0 km / hour) as the leading vehicle. In addition, the microcomputer 12051 can pre-set the following distance of the leading vehicle in front of the vehicle that should be ensured, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. Thus, it is possible to perform coordinated control intended for automatic driving that allows the vehicle to travel automatically without relying on the driver's operation, etc.

[0214] For example, the microcomputer 12051 can classify the three-dimensional object data related to the three-dimensional object into three-dimensional object data of a two-wheeled vehicle, a standard-sized vehicle, a large vehicle, a pedestrian, a utility pole, and other three-dimensional objects based on the distance information obtained from the imaging units 12101 to 12104, extract the classified three-dimensional object data, and use the extracted three-dimensional object data for automatic avoidance of obstacles. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 as obstacles that can be visually recognized by the driver of the vehicle 12100 and obstacles that are difficult for the driver of the vehicle 12100 to visually recognize. Then, the microcomputer 12051 determines a collision risk indicating the risk of collision with each obstacle. In the case where the collision risk is equal to or higher than the set value and therefore there is a possibility of collision, the microcomputer 12051 outputs a warning to the driver via the audio speaker 12061 or the display unit 12062, and performs forced deceleration or evasive steering via the driving system control unit 12010. The microcomputer 12051 can thereby assist driving to avoid collisions.

[0215] At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 may identify a pedestrian by determining whether there is a pedestrian in the image imaged by the imaging units 12101 to 12104. For example, such identification of pedestrians is performed by extracting feature points in the image imaged by the imaging units 12101 to 12104 as infrared cameras and performing pattern matching processing on a series of feature points representing the outline of an object to determine whether it is a pedestrian. When the microcomputer 12051 determines that there is a pedestrian in the image imaged by the imaging units 12101 to 12104 and thus identifies the pedestrian, the sound / image output unit 12052 controls the display unit 12062 so that a square outline for emphasis is displayed as superimposed on the identified pedestrian. The sound / image output unit 12052 may also control the display unit 12062 so that an icon representing a pedestrian is displayed at a desired position, etc.

[0216] An embodiment of a vehicle control system to which the technology according to the present disclosure can be applied has been described above. The technology according to the present disclosure can be applied to, for example, the imaging unit 12031 in the above-mentioned configuration. Specifically, the distance measuring device including the light receiving device according to each embodiment in the above-mentioned embodiment can be applied to the imaging unit 12031. By applying the technology according to the present disclosure to the imaging unit 12031, the amount of current required for ESD surge protection can be ensured without depending on the circuit configuration, size, etc. of the pixel circuit of the effective pixel 101, and therefore, the circuit elements constituting the pixel circuit can be reliably protected from the influence of ESD surges.

[0217] Note that the effects described in this specification are merely embodiments and are not limited to them; there may be another effect.

[0218] <5. Configurations that this technology can adopt>

[0219] It should be noted that the present technology can also have the following configurations.

[0220] (1) A light receiving device comprising:

[0221] an effective pixel including a light receiving element that detects the presence or absence of a photon and a readout circuit of the pixel that processes a signal output from the light receiving element;

[0222] Pseudo pixels, which include light-receiving elements that do not contribute to detecting the presence or absence of photons;

[0223] a first terminal configured to apply a predetermined voltage to a light receiving element of the effective pixel and a light receiving element of the dummy pixel;

[0224] a second terminal configured to provide a first power supply voltage to a readout circuit; and

[0225] A protection circuit includes a diode element connected between a light receiving element of the dummy pixel and a second terminal in a reverse polarity relationship relative to the light receiving element of the dummy pixel, and protects the light receiving element of the effective pixel and circuit elements of the readout circuit from overvoltage.

[0226] (2) The light receiving device according to (1), wherein:

[0227] In an effective pixel, a readout circuit of the pixel is formed in a pixel formation region paired with a light receiving element, and

[0228] In the dummy pixel, a diode element is formed in a pixel formation region corresponding to a pixel formation region of an effective pixel.

[0229] (3) The light receiving device according to (1) or (2), wherein:

[0230] The light receiving element of the effective pixel and the light receiving element of the dummy pixel are avalanche diodes.

[0231] (4) The light receiving device according to (3), wherein

[0232] The light receiving element of the effective pixel and the light receiving element of the dummy pixel are single photon avalanche diodes.

[0233] (5) The light receiving device according to (4), wherein

[0234] As the diode element, a single-photon avalanche diode of a dummy pixel adjacent to the dummy pixel to which the diode element belongs is used.

[0235] (6) The optical receiving device according to (4), further comprising:

[0236] a third terminal configured to apply a second power supply voltage to a readout circuit of the effective pixel; and

[0237] At least one of the surge current paths includes a diode element connected to the light receiving element of the dummy pixel in a forward polarity relationship between the first terminal and the second terminal, or a diode element connected to the light receiving element of the dummy pixel in a forward polarity relationship between the first terminal and the third terminal.

[0238] (7) The light receiving device according to any one of (1) to (6), wherein

[0239] The readout circuit of the effective pixel is configured using a thin film transistor.

[0240] (8) A light receiving device comprising:

[0241] a first light receiving element;

[0242] a quenching element connected between a first node serving as an anode or a cathode of the first light receiving element and a node of a first power supply voltage;

[0243] a transistor connected between a node of a first power supply voltage and a node of a second power supply voltage;

[0244] a second light receiving element; and

[0245] a diode element connected between a second node which is an anode or a cathode of the second light receiving element and a node of a second power supply voltage and connected to the second light receiving element in a reverse polarity relationship, wherein,

[0246] The first light receiving element and the second light receiving element receive a predetermined voltage at nodes opposite to the first node and the second node.

[0247] (9) The light receiving device according to (8), wherein:

[0248] The first light receiving element is arranged in the effective pixel area, and

[0249] The second light receiving element is arranged in the dummy pixel region.

[0250] (10) The optical receiving device according to (8) or (9), further comprising:

[0251] a first substrate including a first light receiving element and a second light receiving element; and

[0252] The second substrate includes a quenching element, a transistor and a diode element.

[0253] (11) A distance measuring device comprising:

[0254] a light source unit that irradiates a distance measurement object with light; and

[0255] a light receiving device that receives reflected light from a distance measurement object based on irradiated light from a light source unit, wherein

[0256] The optical receiving device comprises:

[0257] an effective pixel including a light receiving element that detects the presence or absence of a photon and a readout circuit of the pixel that processes a signal output from the light receiving element;

[0258] Pseudo pixels, which include light-receiving elements that do not contribute to detecting the presence or absence of photons;

[0259] a first terminal configured to apply a predetermined voltage to a light receiving element of the effective pixel and a light receiving element of the dummy pixel;

[0260] a second terminal configured to apply a first power supply voltage to the readout circuit; and

[0261] A protection circuit includes a diode element connected between a light receiving element of the dummy pixel and a second terminal in a reverse polarity relationship relative to the light receiving element of the dummy pixel, and protects the light receiving element of the effective pixel and circuit elements of the readout circuit from overvoltage.

[0262] Reference Symbols List

[0263] 1Distance measuring device

[0264] 10 objects (distance measurement objects)

[0265] 20 Light source unit

[0266] 21 Laser drive unit

[0267] 22 Laser light source

[0268] 23. Diffuser lens

[0269] 30 Light receiving device

[0270] 31 Light receiving lens

[0271] 32 Optical Sensors

[0272] 33 Signal Processing Unit

[0273] 40 Control Unit

[0274] 50 pixels

[0275] 50A pixel readout circuit (logic circuit)

[0276] 51SPAD Component

[0277] 54 Quenching element

[0278] 55CMOS Inverter

[0279] 56 High voltage protection components

[0280] 58, 58A logic circuit protection circuit

[0281] 59 Surge current path

[0282] 61 first semiconductor substrate

[0283] 62 second semiconductor substrate

[0284] 63 wiring layer

[0285] 64 Joint such as Cu-Cu joint

[0286] 100 Active pixel area

[0287] 101 effective pixels

[0288] 200 Pseudo-pixel area

[0289] 201 Pseudo Pixel

[0290] 201A Circuit formation area

[0291] 202SPAD Component

[0292] 203, 205, 206 diode elements

[0293] 204, 207, 208, 209 surge current paths

Claims

1. A light receiving device, comprising: an effective pixel including a light receiving element that detects the presence or absence of a photon and a readout circuit of the pixel that processes a signal output from the light receiving element; Pseudo pixels, which include light-receiving elements that do not contribute to detecting the presence or absence of photons; a first terminal configured to apply a predetermined voltage to the light receiving element of the effective pixel and the light receiving element of the dummy pixel; a second terminal configured to provide a first power supply voltage to the readout circuit; as well as A protection circuit includes a diode element, which is connected between the light receiving element of the dummy pixel and the second terminal in a reverse polarity relationship relative to the light receiving element of the dummy pixel, and protects the light receiving element of the effective pixel and the circuit elements of the readout circuit from overvoltage.

2. The optical receiving device according to claim 1, further comprising: A first substrate including a light receiving element of the effective pixel and a light receiving element of the dummy pixel; as well as The second substrate includes the readout circuit and the protection circuit.

3. The light receiving device according to claim 1, wherein The light receiving element of the effective pixel and the light receiving element of the dummy pixel are avalanche diodes.

4. The light receiving device according to claim 3, wherein: The light receiving element of the effective pixel and the light receiving element of the dummy pixel are single photon avalanche diodes.

5. The light receiving device according to claim 4, wherein: As the diode element, a single-photon avalanche diode of a dummy pixel adjacent to the dummy pixel to which the diode element belongs is used.

6. The optical receiving device according to claim 4, further comprising: a third terminal configured to apply a second power supply voltage to a readout circuit of the effective pixel; as well as At least one of the surge current paths includes a diode element connected to the light receiving element of the pseudo pixel in a forward polarity relationship between the first terminal and the second terminal, or a surge current path includes a diode element connected to the light receiving element of the pseudo pixel in a forward polarity relationship between the first terminal and the third terminal.

7. The light receiving device according to claim 1, wherein: The readout circuit of the effective pixel is configured using a thin film transistor.

8. A light receiving device, comprising: a first light receiving element; a quenching element connected between a first node serving as an anode or a cathode of the first light receiving element and a node of a first power supply voltage; a transistor connected between a node of the first power supply voltage and a node of a second power supply voltage; a second light receiving element; as well as a diode element connected between a second node which is an anode or a cathode of the second light receiving element and a node of the second power supply voltage and connected to the second light receiving element in a reverse polarity relationship, wherein, The first light receiving element and the second light receiving element receive a predetermined voltage at nodes opposite to the first node and the second node.

9. The light receiving device according to claim 8, wherein: The first light receiving element is arranged in an effective pixel area, and The second light receiving element is arranged in a dummy pixel region.

10. The optical receiving device according to claim 8, further comprising: a first substrate including the first light receiving element and the second light receiving element; as well as The second substrate includes the quenching element, the transistor and the diode element.

11. A distance measuring device, comprising: a light source unit that irradiates a distance measurement object with light; as well as a light receiving device that receives reflected light from the distance measurement object based on the irradiation light from the light source unit, wherein The light receiving device comprises: an effective pixel including a light receiving element that detects the presence or absence of a photon and a readout circuit of the pixel that processes a signal output from the light receiving element; Pseudo pixels, which include light-receiving elements that do not contribute to detecting the presence or absence of photons; a first terminal configured to apply a predetermined voltage to the light receiving element of the effective pixel and the light receiving element of the dummy pixel; and A protection circuit includes a diode element, which is connected between the light receiving element of the dummy pixel and the second terminal in a reverse polarity relationship relative to the light receiving element of the dummy pixel, and protects the light receiving element of the effective pixel and the circuit elements of the readout circuit from overvoltage.

Images