Light detection device and ranging system

Abstract

This light detection device comprises: an avalanche photodiode in which a first fixed voltage is applied to one of an anode region and a cathode region, and a carrier generated by an incident photon is multiplied; a protection circuit which is electrically connected in series to the other of the anode region and the cathode region, and which has a resistance element (R) for protecting an internal circuit against an overcurrent; and a first conductor (1141) which is electrically connected in parallel to the resistance element (R).

Description

Optical detection device and ranging system

[0001] The present disclosure relates to a light detection device and a ranging system.

[0002] Patent Document 1 discloses a light receiving device and a distance measuring device. The light receiving device includes a light receiving element that generates a signal in response to input of photons. The light receiving element is a photodetector. For example, a single photon avalanche diode (SPAD) is used as the light receiving element. The distance measuring device includes a light receiving device. In the distance measuring device, light is irradiated from a light source toward an object (subject) to be measured, and the time of flight (ToF) of the light reflected by the object to be measured is measured. In other words, the distance measuring device measures the distance to the object to be measured. For example, highly directional laser light is used as the light.

[0003] U.S. Patent Application Publication No.: US 2023 / 0145695 A1

[0004] The light receiving device, or the light receiving device and distance measuring device disclosed in Patent Document 1, includes a protection circuit. When a greater amount of light than expected is incident on the SPAD of the light receiving device, such as when laser light is directly irradiated, the effect of photoelectric conversion in the SPAD increases, resulting in a significant drop in internal impedance. This phenomenon causes excessive voltage to be applied to a readout circuit that reads out the photoelectrically converted signal in the SPAD. The protection circuit includes a resistive element and can mitigate the excessive voltage applied to the readout circuit. In light detection devices and distance measuring systems, it is desirable to further improve the resistance of the resistive element against excessive voltage and improve the characteristics of the protection circuit.

[0005] A photodetector according to a first embodiment of the present disclosure includes an avalanche photodiode having a first fixed voltage applied to one of an anode region and a cathode region, which multiplies carriers generated by incident photons; a protection circuit electrically connected in series to the other of the anode region and the cathode region and having a resistive element that protects the internal circuitry against overcurrent; and a first conductor electrically connected in parallel to the resistive element.

[0006] In a photodetector according to a second embodiment of the present disclosure, the first conductor in the photodetector according to the first embodiment is disposed opposite a second conductor electrically connected to a second fixed voltage, with an insulator interposed therebetween. Furthermore, in the photodetector, the first conductor, the insulator, and the second conductor form a capacitive element that protects the resistive element against overcurrent.

[0007] In a photodetector according to a third embodiment of the present disclosure, in the photodetector according to the first embodiment, the resistive element is formed to include polycrystalline silicon, metal, or an insulated gate field effect transistor.

[0008] In a photodetector according to a fourth embodiment of the present disclosure, the polarity of the resistive element in the photodetector according to the first embodiment is the same as or different from the polarity of the other of the anode region and cathode region of the avalanche photodiode.

[0009] A ranging system according to a fifth embodiment of the present disclosure includes a photodetector and a circuit device. The photodetector includes an avalanche photodiode having a first fixed voltage applied to one of an anode region and a cathode region, which multiplies carriers generated by incident photons, a protection circuit electrically connected in series to the other of the anode region and the cathode region and having a resistive element for protecting the internal circuit against overcurrent, and a first conductor electrically connected in parallel to the resistive element. The circuit device includes an internal circuit electrically connected to the avalanche photodiode through the protection circuit and constituting a readout circuit for reading out the multiplied carriers, and a time measurement circuit electrically connected to the internal circuit and for measuring the time of flight of light.

[0010] FIG. 1 is a circuit configuration diagram of a portion of a photodetector and a ranging system according to a first embodiment of the present disclosure. FIG. 2 is a longitudinal cross-sectional configuration diagram of a photodetector element (light-receiving element) of the photodetector shown in FIG. 1. FIG. 3 is a plan configuration diagram of a portion of a protection circuit arranged in the photodetector shown in FIG. 1. FIG. 4 is a plan configuration diagram corresponding to FIG. 3 of a portion of a protection circuit arranged in a photodetector according to a second embodiment of the present disclosure. FIG. 5 is a plan configuration diagram corresponding to FIG. 3 of a portion of a protection circuit arranged in a photodetector according to a third embodiment of the present disclosure. FIG. 6 is a plan configuration diagram corresponding to FIG. 3 of a portion of a protection circuit arranged in a photodetector according to a fourth embodiment of the present disclosure. FIG. 7 is a plan configuration diagram corresponding to FIG. 3 of a portion of a protection circuit arranged in a photodetector according to a fifth embodiment of the present disclosure. FIG. 8 is a plan configuration diagram corresponding to FIG. 3 of a portion of a protection circuit arranged in a photodetector according to a sixth embodiment of the present disclosure. FIG. 9 is a plan configuration diagram corresponding to FIG. 3 of a portion of a protection circuit arranged in a photodetector according to a seventh embodiment of the present disclosure. FIG. 10 is a longitudinal cross-sectional configuration diagram corresponding to FIG. 2 of a photodetector element of a photodetector according to an eighth embodiment of the present disclosure. FIG. 11 is a plan configuration diagram corresponding to FIG. 3 of a portion of a protection circuit disposed in the photodetector shown in FIG. 10. FIG. 12 is a longitudinal cross-sectional configuration diagram corresponding to FIG. 2 of a photodetector element of a photodetector according to a ninth embodiment of the present disclosure. FIG. 13 is a plan configuration diagram corresponding to FIG. 3 of a portion of a protection circuit disposed in the photodetector shown in FIG. 12. FIG. 14 is a longitudinal cross-sectional configuration diagram corresponding to FIG. 2 of a photodetector element of a photodetector according to a tenth embodiment of the present disclosure. FIG. 15 is a circuit configuration diagram corresponding to FIG. 1 of a portion of a photodetector and a ranging system according to an eleventh embodiment of the present disclosure. FIG. 16 is a longitudinal cross-sectional configuration diagram corresponding to FIG. 2 of a photodetector element of the photodetector shown in FIG. 15. FIG. 17 is a circuit configuration diagram corresponding to FIG. 1 of a portion of a photodetector and a ranging system according to a twelfth embodiment of the present disclosure. FIG. 18 is a circuit configuration diagram corresponding to FIG. 1 of a portion of a photodetector and a ranging system according to a thirteenth embodiment of the present disclosure. Fig. 19 is a circuit configuration diagram of a part of a photodetector and a distance measuring system according to a fourteenth embodiment of the present disclosure, corresponding to Fig. 1. Fig. 20 is a circuit configuration diagram of a part of a photodetector and a distance measuring system according to a fifteenth embodiment of the present disclosure, corresponding to Fig. 1.Fig. 21 is a circuit configuration diagram of a part of a light detection device and a ranging system according to a sixteenth embodiment of the present disclosure, corresponding to Fig. 1. Fig. 22 is a block diagram showing an example of a schematic configuration of a vehicle control system. Fig. 23 is an explanatory diagram showing an example of installation positions of an outside-vehicle information detection unit and an imaging unit.

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be made in the following order. 1. First Embodiment The first embodiment describes a first example in which the present technology is applied to a photodetector and a ranging system. The first embodiment describes in detail the circuit configuration and device configuration of a photodetector having one or more photodetecting elements (or light receiving elements or pixels) and a ranging system including the photodetector. Here, at least one of the photodetector and the ranging system includes a protection circuit having a resistive element. 2. Second Embodiment The second embodiment describes a second example in which the configurations of the resistive elements and the capacitive elements of the protection circuit are changed in the photodetector and ranging system according to the first embodiment. 3. Third Embodiment The third embodiment describes a third example in which the configurations of the resistive elements and the capacitive elements of the protection circuit are changed in the photodetector and ranging system according to the second embodiment. 4. Fourth Embodiment The fourth embodiment describes a fourth example in which the configurations of the resistive elements and the capacitive elements of the protection circuit are changed in the photodetector and ranging system according to the second embodiment. 5. Fifth Embodiment The fifth embodiment describes a fifth example in which the configurations of the resistive elements and capacitive elements of the protection circuit are changed in the photodetector and ranging system according to the fourth embodiment. 6. Sixth Embodiment The sixth embodiment describes a sixth example in which the configurations of the resistive elements and capacitive elements of the protection circuit are changed in the photodetector and ranging system according to the third embodiment. 7. Seventh Embodiment The seventh embodiment describes a seventh example in which the photodetector and ranging system according to the fourth embodiment is combined with the photodetector and ranging system according to the sixth embodiment. 8. Eighth Embodiment The eighth embodiment describes an eighth example in which the configurations of the resistive elements and capacitive elements of the protection circuit are changed in the photodetector and ranging system according to the sixth embodiment. 9. Ninth Embodiment The ninth embodiment describes a seventh example in which the photodetector and ranging system according to the fifth embodiment is combined with the photodetector and ranging system according to the seventh embodiment. The ninth example will be described. 10. Tenth Embodiment In the tenth embodiment, a tenth example will be described in which the configurations of the resistive elements and capacitive elements of the protection circuit are changed in the photodetector and distance measuring system according to the first embodiment.11. Eleventh Embodiment The eleventh embodiment describes an eleventh example in which the configurations of the resistive elements and capacitive elements of the protection circuit are changed in the photodetector and ranging system according to the first embodiment. 12. Twelfth Embodiment The twelfth embodiment describes a twelfth example in which the configurations of the resistive elements and capacitive elements of the protection circuit are changed in the photodetector and ranging system according to the first embodiment. 13. Thirteenth Embodiment The thirteenth embodiment describes a thirteenth example in which the configurations of the resistive elements and capacitive elements of the protection circuit are changed in the photodetector and ranging system according to the first embodiment. 14. Fourteenth Embodiment The fourteenth embodiment describes a fourteenth example in which the configurations of the resistive elements and capacitive elements of the protection circuit are changed in the photodetector and ranging system according to the first embodiment. 15. Fifteenth Embodiment The fifteenth embodiment describes a fifteenth example in which the configurations of the resistive elements and capacitive elements of the protection circuit are changed in the photodetector and ranging system according to the first embodiment. 16. Sixteenth Embodiment The sixteenth embodiment describes a sixteenth example in which the configurations of the resistive elements and capacitive elements of the protection circuit are changed in the photodetector and ranging system according to the fifteenth embodiment. 17. Application Example to a Mobile Body This application example describes an example in which the present technology is applied to a vehicle control system, which is an example of a mobile body control system. 18. Other Embodiments

[0012] 1 to 3 , a light detection device 1 and a ranging system 6 according to a first embodiment of the present disclosure will be described. Here, the arrow X direction shown as appropriate in the figures indicates one planar direction of the light detection device 1 and ranging system 6 placed on a flat surface for convenience. The arrow Y direction indicates another planar direction perpendicular to the arrow X direction. Furthermore, the arrow Z direction indicates an upward direction perpendicular to the arrow X direction and the arrow Y direction. In other words, the arrow X direction, the arrow Y direction, and the arrow Z direction exactly correspond to the X-axis direction, the Y-axis direction, and the Z-axis direction, respectively, of a three-dimensional coordinate system. Note that these directions are shown to facilitate understanding of the description and do not limit the directions of the present technology.

[0013] [Circuit configuration of the photodetector 1 and the ranging system 6] (1) Overall schematic configuration of the photodetector 1 and the ranging system 6 FIG. 1 shows an example of the circuit configuration of the photodetector 1 and the ranging system 6 according to the first embodiment.

[0014] First, a distance measurement system 6 to which the present technology is applied measures the distance to a subject as a distance measurement target. More specifically, the distance measurement system 6 uses a ToF method to measure the distance. The ToF method is a method in which light is irradiated toward a subject, light reflected from the subject is received, and the time of flight of the light from irradiation to reception is measured. For example, a laser beam with excellent directionality and a peak wavelength in the near-infrared wavelength band is used as the light. The distance measurement system 6 can also be used as a photon counter.

[0015] Therefore, the distance measurement system 6 is equipped with a photodetection device 1. The photodetection device 1 includes one or more photodetection elements that receive light and are used to measure the distance to a subject. The photodetection elements are light-receiving elements and also light-receiving pixels.

[0016] 1, the distance measurement system 6 includes at least a photodetector 1. In the first embodiment, the distance measurement system 6 includes at least the photodetector 1 and a circuit device 5. Note that the distance measurement system 6 may also include a laser light oscillator having a laser light source (not shown) as a device for realizing the ToF method.

[0017] (2) Circuit Configuration of the Photodetector 1 As shown in Fig. 1, the photodetector 1 is constructed as a sensor element or a sensor chip. The photodetector 1 includes pixels 10 each including an avalanche photodiode 11 as a photodetector element. Fig. 1 shows one pixel 10. In reality, the photodetector 1 has a plurality of pixels 10 arranged in a matrix.

[0018] The avalanche photodiode 11 is a single-photon avalanche diode that multiplies carriers generated by incident photons. In other words, the avalanche photodiode 11 is a SPAD (Single Photon Avalanche Diode). The avalanche photodiode 11 operates in a nonlinear region (Geiger mode). In other words, the avalanche photodiode 11 is set to a predetermined breakdown voltage (predetermined breakdown voltage) and operates with a reverse voltage that exceeds the predetermined breakdown voltage.

[0019] An anode power supply line VLsp is electrically connected to the anode region (anode electrode) of the avalanche photodiode 11. An anode voltage Vsp is supplied to the anode region from the anode power supply line VLsp. The anode voltage Vsp is a large negative voltage that generates avalanche multiplication, or in other words, a fixed voltage (first fixed voltage) equal to or higher than a predetermined breakdown voltage. The anode voltage Vsp is, for example, a voltage equal to or higher than −20 V.

[0020] The cathode region (cathode electrode) of the avalanche photodiode 11 is connected to the readout circuit 3 via the protection circuit 2. A cathode voltage clamped by (the second protection circuit 22 of) the protection circuit 2 is applied to the cathode region. The cathode voltage is a voltage of, for example, about 3 V, supplied from the operating power supply Vd.

[0021] (3) Circuit Configuration of First Protection Circuit 21 of Protection Circuit 2 The protection circuit 2 includes a first protection circuit 21 and a second protection circuit 22. The photodetector 1 is provided with the first protection circuit 21 in addition to the pixels 10. When a greater amount of photons than expected is incident on the avalanche photodiode 11, the internal impedance of the avalanche photodiode 11 drops significantly, causing an overcurrent to flow in the readout circuit 3. The first protection circuit 21 is configured to reduce this overcurrent and protect the readout circuit 3.

[0022] In the first embodiment, the first protection circuit 21 includes a resistive element R and also includes a capacitive element C. The resistive element R is electrically connected in series between the avalanche photodiode 11 and the readout circuit 3. More specifically, one end of the resistive element R is electrically connected in series to the cathode region of the avalanche photodiode 11. The other end of the resistive element R is electrically connected in series to the readout circuit 3. The first protection circuit 21 is arranged closer to the avalanche photodiode 11 than the second protection circuit 22.

[0023] The capacitance element C is electrically connected in parallel to the resistance element R. A detailed description will be given. One electrode of the capacitance element C is electrically connected to the resistance element R. The other electrode of the capacitance element C is disposed so that at least a portion thereof faces the one electrode, with an insulator (dielectric) interposed therebetween. The other electrode is electrically connected to a fixed power supply Vc. That is, a fixed voltage (second fixed voltage) is supplied to the other electrode from the fixed power supply Vc. The fixed voltage is, for example, the same as the voltage supplied from the reference power supply Vs or the voltage supplied from the operating power supply Vd. Here, the one electrode corresponds to a "first conductor 1141" or a part thereof according to the present technology (see FIGS. 2 and 3). The other electrode corresponds to a "second conductor 1142" or a part thereof according to the present technology (see FIG. 2).

[0024] When a larger amount of photons than expected is incident on the avalanche photodiode 11, the internal impedance of the avalanche photodiode 11 drops significantly, causing an overcurrent to flow through the resistance element R. The capacitance element C is configured to reduce (absorb) such an overcurrent, protect the resistance element R, and improve the withstand capability of the resistance element R. In other words, the capacitance element C is configured to improve the withstand capability of the resistance element R and protect the first protection circuit 21.

[0025] (4) Circuit Configuration of Circuit Device 5 The circuit device 5 is constructed as a circuit element or a circuit chip. The circuit device 5 includes the second protection circuit 22 of the protection circuit 2, the readout circuit 3, and the time measurement circuit 4.

[0026] (5) Circuit Configuration of Second Protection Circuit 22 The second protection circuit 22 is disposed between the first protection circuit 21 and the readout circuit 3. The second protection circuit 22 includes a first clamp element Tc1 and a second clamp element Tc2. That is, the second protection circuit 22 is configured to clamp an overcurrent flowing from the second protection circuit 21 to the readout circuit 3, thereby protecting the readout circuit 3.

[0027] The first clamp element Tc1 is configured by a p-type insulated gate field effect transistor (IGFET) of a first conductivity type. Hereinafter, the insulated gate field effect transistor will be simply referred to as an "IGFET." Hereinafter, the term "IGFET" is used to encompass MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) and MISFETs (Metal Insulator Semiconductor Field Effect Transistors). The IGFET is configured to include a pair of main electrodes serving as a source electrode and a drain electrode, a gate insulating film, and a gate electrode.

[0028] One of the pair of main electrodes and the gate electrode of the first clamp element Tc1 are electrically connected to the other end of the resistor element R of the first protection circuit 21. The other of the pair of main electrodes of the first clamp element Tc1 is electrically connected to a reference power supply Vs. That is, the first clamp element Tc1 is electrically connected in parallel between the second protection circuit 22 and the readout circuit 3. The reference power supply Vs supplies a voltage of, for example, 0 V.

[0029] The first clamp element Tc1 may also be configured as a diode element (clamp diode element) electrically connected in parallel between the resistor element R and the second clamp element Tc2. The diode element has an anode region electrically connected to the reference power supply Vs and a cathode region electrically connected to the resistor element R and the second clamp element Tc2. In other words, the diode element is configured to be inserted in the reverse direction.

[0030] The second clamp element Tc2, like the first clamp element Tc1, is configured as a p-type IGFET. One of a pair of main electrodes of the second clamp element Tc2 is electrically connected to the other main electrode of the first clamp element Tc1. The other of the pair of main electrodes of the second clamp element Tc2 is electrically connected to the readout circuit 3. The gate electrode of the second clamp element Tc2 is electrically connected to the reference power supply Vs.

[0031] (6) Circuit Configuration of Readout Circuit 3 The readout circuit 3 is configured to include a first control element T1, a second control element T2, a first output element T3, and a second output element T4.

[0032] In the readout circuit 3, the first control element T1 is used as a quench element and is composed of a p-type IGFET. One of a pair of main electrodes of the first control element T1 is electrically connected to an operating power supply Vd via an ammeter (reference numeral omitted). The other of the pair of main electrodes of the first control element T1 is electrically connected to the second protection circuit 22, the second control element T2, the first output element T3, and the second output element T4. An enable signal EN is input to the gate electrode of the first control element T1.

[0033] When a low-level enable signal EN is input, the first control element T1 becomes conductive and supplies the operating voltage from the operating power supply Vd to the avalanche photodiode 11. That is, the avalanche current is drawn out by the first control element T1, and the readout circuit 3 enters a reset state.

[0034] The second control element T2 is configured as an n-type IGFET having a second conductivity type opposite to the first conductivity type. One of a pair of main electrodes of the second control element T2 is electrically connected to the reference power supply Vs. The other of the pair of main electrodes of the second control element T2 is electrically connected to the second protection circuit 22, the first control element T1, the first output element T3, and the second output element T4. A signal xEN having an opposite phase to the enable signal EN is input to the gate electrode of the second control element T2. When the high-level signal xEN is input, the second control element T2 is brought into a conductive state. In other words, a reference voltage is supplied from the reference power supply Vs to the cathode electrode of the avalanche photodiode 11, and the readout circuit 3 is brought into an active state.

[0035] The first output element T3 and the second output element T4 form a complementary output circuit. The first output element T3 is configured as a p-type IGFET. One of a pair of main electrodes of the first output element T3 is electrically connected to the operating power supply Vd. The other of the pair of main electrodes of the first output element T3 is electrically connected to the time measurement circuit 4. The gate electrode of the first output element T3 is electrically connected to the other of the main electrodes of the first control element T1 and the second control element T2. When a low-level signal is input to the gate electrode in response to the output of the avalanche photodiode 11, the first output element T3 becomes conductive. This causes the readout circuit 3 to output a high-level readout signal to the time measurement circuit 4. When a high-level signal is input to the gate electrode, the first output element T3 becomes non-conductive.

[0036] The second output element T4 is configured as an n-type IGFET. One of a pair of main electrodes of the second output element T4 is electrically connected to the reference power supply Vs. The other of the pair of main electrodes of the second output element T4 is electrically connected to the time measurement circuit 4. The gate electrode of the second output element T4 is electrically connected to the other of the main electrodes of the first control element T1 and the second control element T2, similar to the gate electrode of the first output element T3. When a high-level signal is input to the gate electrode in response to the output of the avalanche photodiode 11, the second output element T4 enters a conductive state. This causes the readout circuit 3 to output a low-level readout signal to the time measurement circuit 4. When a low-level signal is input to the gate electrode, the second output element T4 enters a non-conductive state.

[0037] (7) Circuit Configuration of Time Measurement Circuit 4 The time measurement circuit 4 is electrically connected to the output of the readout circuit 3. The output of the readout circuit 3 is output to the time measurement circuit 4 as the output of the avalanche photodiode 11 (the output of the pixel 10). Based on the output of the avalanche photodiode 11, the time measurement circuit 4 measures the time of flight of light that is irradiated onto a subject (object to be measured), reflected by the subject, and returns.

[0038] In the first embodiment, the time measurement circuit 4 is configured as a hardware circuit. However, the time measurement circuit 4 may be configured as a software circuit, including an input circuit, an output circuit, a central processing unit (CPU), a memory unit, etc.

[0039] [Device Configuration of Photodetector 1 and Distance Measuring System 6] (1) Longitudinal Cross-Sectional Configuration of Photodetector 1 Fig. 2 shows an example of a longitudinal cross-sectional configuration of a photodetector 1 including pixels 10. The photodetector 1 is stacked on a separately manufactured circuit device 5. The stacked photodetector 1 and circuit device 5 constitute a distance measuring system 6.

[0040] 3, the photodetector 1 is constructed with a base 101 as a base when viewed in the direction of the arrow Y (hereinafter simply referred to as "side view"). In the first embodiment, the base 101 is formed of, for example, a single-crystal silicon (Si) substrate into which n-type impurities are introduced at a low impurity density. Here, the base 101 corresponds to a "first base" according to the present technology.

[0041] Pixels 10 each having an avalanche photodiode 11 are disposed on a base 101. In a side view, an insulating separator 102 is disposed in a region of the base 101 surrounding the side periphery of the pixel 10. The insulating separator 102 physically separates the pixel 10 from other pixels 10 (not shown) adjacent in the directions indicated by arrows X and Y, and is configured to at least electrically and optically separate the avalanche photodiodes 11 from each other.

[0042] (2) Configuration of the insulating isolator 102 Here, the insulating isolator 102 includes an isolation trench 102A and a filling member 102B. This will be described in detail.

[0043] In a side view, the isolation trench 102A penetrates from the first surface 101A on the arrow Z direction side of the base 101 to the second surface 101B facing the opposite side. In other words, the isolation trench 102A is disposed to penetrate the base 101 in the thickness direction. Here, the isolation trench 102A extends with a constant width in each of the arrow X direction and the arrow Y direction. For this reason, although not shown, the planar shape of the insulating isolator 102 is formed in a lattice shape when viewed from the arrow Z direction (hereinafter simply referred to as "in a planar view"). Furthermore, the planar shape of the pixel 10 surrounded by the lattice-shaped insulating isolator 102 is formed in a rectangular shape, specifically a square shape.

[0044] The filling member 102B is filled in the isolation trench 102A. In the first embodiment, the filling member 102B is made of silicon oxide (SiO ２ ) or other insulating material.

[0045] The planar shape of the pixel 10 is not necessarily limited to a rectangular shape, and the planar shape of the insulating isolator 102 is not limited to a lattice shape. For example, the planar shape of the pixel 10 may be formed into a rectangular shape, a polygonal shape with pentagons or more sides, a circular shape, or an elliptical shape. When the planar shape of this pixel 10 is changed, the planar shape of the insulating isolator 102 is changed to correspond to the changed shape.

[0046] (3) Configuration of Pixel 10 The pixel 10 is disposed in an n-type semiconductor region (n-type well region) 103 formed in the base 101 within a region surrounded by an insulating isolator 102. The n-type semiconductor region 103 is formed with a low impurity concentration. As described above, the pixel 10 includes an avalanche photodiode (SPAD) 11. The avalanche photodiode 11 is disposed inside the insulating isolator 102, with a p-type semiconductor region 106 interposed therebetween, the p-type semiconductor region 106 being formed along the inner wall of the insulating isolator 102. The p-type semiconductor region 106 is used as a pinning region to suppress the generation of dark current. Furthermore, the p-type semiconductor region 106 is used as part of the anode power supply line VLsp.

[0047] The avalanche photodiode 11 includes an anode region 104 and a cathode region 105. The anode region 104 is disposed on the second surface 101B side of the base 101. The anode region 104 is formed of a p-type semiconductor region having a higher impurity density than the p-type semiconductor region 106. In addition, the anode region 104 is formed on the inner wall of the insulating separator 102 with the p-type semiconductor region 106 interposed therebetween in a planar view. Therefore, the planar shape of the anode region 104 is formed in a rectangular shape, similar to the planar shape of the pixel 10.

[0048] An anode voltage Vsp (see FIG. 1) is supplied to the anode region 104 through the p-type semiconductor region 106. In other words, the anode voltage Vsp is supplied to the anode region 104 from the periphery of the pixel 10.

[0049] The cathode region 105 is disposed between the second surface 101B of the base 101 and the anode region 104. The cathode region 105 is formed of an n-type semiconductor region having an impurity density higher than that of the n-type semiconductor region 103. The cathode region 105 is joined to the anode region 104 by a pn junction. In addition, the cathode region 105 is formed on the inner wall of the insulating isolator 102 with the n-type semiconductor region 103 of the base 101 interposed therebetween in a planar view. Therefore, the planar shape of the cathode region 105 is formed in a rectangular shape, similar to the anode region 104, but slightly smaller than the planar shape of the anode region 104.

[0050] (4) Configuration of Optical Filter 108 and Optical Lens 109 In the pixel 10, the optical filter 108 and the optical lens 109 are sequentially stacked on the first surface 101A of the base 101. In side view, the optical filter 108 is embedded in a portion of the first surface 101A that has an uneven cross-sectional shape formed in the n-type semiconductor region 103. In other words, the first surface 101A side of the optical filter 108 is formed with an uneven cross-sectional shape. In addition, the surface of the optical filter 108 that faces the optical lens 109 is flattened. The optical filter 108 scatters light that is incident through the optical lens 109, causing the light to be received by the avalanche photodiode 11.

[0051] On the other hand, in a side view, the surface of the optical lens 109 on the arrow Z direction side is formed into a shape that curves in the arrow Z direction for each pixel 10 or for each set of multiple pixels 10. In other words, the optical lens 109 collects incident light. The light collected by the optical lens 109 is received by the avalanche photodiode 11. The optical lens 109 is made of, for example, a transparent resin material. Here, the optical lens 109 is formed as an on-chip lens.

[0052] (5) Configuration of Wiring Layer 111 As shown in Fig. 2, a wiring layer 111 is disposed on the second surface 101B of the base 101. The wiring layer 111 includes a connection hole wiring 112, a wiring 113, a wiring 114, and an insulator 115. The wiring layer 111 is configured to electrically connect between the avalanche photodiode 11 of the photodetector 1 and the protection circuit 2, between the protection circuit 2 and the readout circuit 3, etc. In other words, the wiring layer 111 is configured to electrically connect between the photodetector 1 and the circuit device 5.

[0053] The wiring 113 is disposed at a position closest to the second surface 101B of the base 101. The wiring 113 is formed of a gate electrode material such as polycrystalline Si. Specifically, the wiring 113 is formed of polycrystalline Si (semiconductor) doped with n-type impurities that adjust the resistance value. This wiring 113 forms the resistor element R of the first protection circuit 21. The resistor element R will be described in detail later.

[0054] The wiring 114 is disposed on the second surface 101B of the base 101, on the side opposite to the direction indicated by the arrow Z, with the wiring 113 interposed therebetween. In the first embodiment, the wiring 114 is formed in multiple layers. The wiring 114 is formed of a wiring material with excellent conductivity, such as copper (Cu) or aluminum (Al)-Cu. In the pixel 10, the wiring 114 is electrically connected to the p-type semiconductor region 106 and forms an anode power supply line VLsp that supplies an anode voltage Vsp to the anode region 104 of the avalanche photodiode 11. The wiring 114 is also formed as a wiring that electrically connects the cathode region 105 of the avalanche photodiode 11 and the resistor element R of the first protection circuit 21.

[0055] Here, the wiring 114 is also formed as one and the other electrodes of the capacitance element C of the first protection circuit 21. The capacitance element C will be described in detail later.

[0056] The contact hole wiring 112 electrically connects between the avalanche photodiode 11 and the wiring 114, between the p-type semiconductor region 106 and the wiring 114, between the wiring 113 and the wiring 114, etc. The contact hole wiring 112 is formed of, for example, a metal material such as W or a wiring material.

[0057] The insulator 115 is actually formed of a plurality of insulating layers. The insulator 115 is configured to electrically separate and protect, for example, the wiring 113 and the wiring 114. The insulator 115 is also used as a dielectric for the capacitance element C. The insulator 115 is made of, for example, SiO ２ It is formed from an insulating material such as the above.

[0058] (6) Configuration of Resistance Element R of First Protection Circuit 21 Fig. 3 shows an example of the planar configuration of the first protection circuit 21 of the protection circuit 2 disposed in the photodetector 1. As described above, the resistance element R of the first protection circuit 21 is formed by the wiring 113 of the wiring layer 111, as shown in Fig. 2. In other words, the polycrystalline Si (semiconductor) that is the resistance element R is indirectly connected to the cathode region of the avalanche photodiode 11 via the via hole wiring (metal) 112.

[0059] 3, the resistor element R extends in the direction of the arrow X while meandering alternately in the direction of the arrow Y and the opposite direction. In other words, the resistor element R is formed in a meandering shape in a plan view. Therefore, the resistor element R can be set to a large resistance value in a small occupation area.

[0060] 2 and 3, the capacitance element C is electrically connected in parallel with the resistance element R. A detailed explanation will be given below. The capacitance element C includes a first conductor 1141 as one electrode, an insulator 115 as a dielectric, and a second conductor 1142 as the other electrode.

[0061] The first conductor 1141 is disposed in the same wiring layer as the wiring 114 close to the resistor element R, and is formed from the same wiring material. The first conductor 1141 is electrically connected in parallel through the connection hole wiring 112 at the middle portion of the resistor element R in the resistor length direction. In the first embodiment, the first conductor 1141 is connected to the middle position of the resistor element R in the resistor length direction. Here, the resistance length of the resistor element R is the length from one end to the other end of the resistor element R. Furthermore, the resistance length direction is the extension direction in which the resistance lengths of the resistor element R are added up.

[0062] The first conductor 1141 is disposed so as to overlap the resistor element R. In other words, the first conductor 1141 is disposed within the region in which the resistor element R is disposed. The first conductor 1141 has an elongated portion extending in the direction of arrow Y from the position connected to the resistor element R, and an elongated portion intersecting the middle portion of the elongated portion in the extension direction and extending in the direction of arrow X. In other words, the first conductor 1141 is formed in a cross shape in a plan view. The width dimension of the elongated portion of the first conductor 1141 is not particularly limited, but is set within the range of the meandering pitch of the resistor element R.

[0063] The second conductor 1142 is disposed in the same wiring layer as the wiring 114 extending from the resistance element R via the first conductor 1141 and the insulator 115, and is formed from the same wiring material. Although not shown, in the first embodiment, the second conductor 1142 is disposed so as to overlap the first conductor 1141 and is formed to have the same planar shape as the first conductor 1141. Of course, the second conductor 1142 may be formed to have a different planar shape from the first conductor 1141, as long as it is disposed so as to overlap the first conductor 1141. In short, it is sufficient that a capacitance element C is formed by the first conductor 1141, the insulator 115, and the second conductor 1142.

[0064] (8) Configuration of Circuit Device 5 Returning to FIG. 2 , the circuit device 5 is constructed based on a base 501. The base 501 is disposed on the second surface 101B side of the base 101. In other words, the photodetector 1 is stacked on the arrow Z direction side of the circuit device 5 in a side view. In the first embodiment, the base 501 is formed of, for example, a single crystal Si substrate, similar to the base 101. Here, the base 501 corresponds to the "second base" according to the present technology.

[0065] The base 501 is provided with elements (see FIG. 1) that constitute the second protection circuit 22 of the protection circuit 2, the readout circuit 3, and the time measurement circuit 4. Detailed configurations and descriptions of the elements etc. are omitted.

[0066] (9) Configuration of the Wiring Layer 511 As shown in Fig. 2, a wiring layer 511 is disposed on the base 501 on the second surface 101B side of the base 101. Although detailed configuration and description thereof will be omitted, the wiring layer 511 includes connection hole wiring, wiring, insulators, etc., similar to the wiring layer 111. The wiring layer 111 and the wiring layer 511 are electrically and mechanically connected to each other via terminals (not shown). For example, Cu-Cu bonding is used for this connection.

[0067] [Operation and Effect] As described above, the photodetector 1 according to the first embodiment includes an avalanche photodiode 11, a protection circuit 2, and a first conductor 1141, as shown in FIGS. 1 to 3. The avalanche photodiode 11 has an anode region to which an anode voltage (first fixed voltage) Vsp is applied, thereby multiplying carriers generated by incident photons. The protection circuit 2 includes a first protection circuit 21. The first protection circuit 21 is electrically connected in series to the cathode region of the avalanche photodiode 11 and includes a resistive element R that protects the readout circuit 3 against overcurrent. The first conductor 1141 is electrically connected in parallel to the resistive element R. With the photodetector 1 configured in this manner, when a greater amount of photons than expected is incident on the avalanche photodiode 11, the internal impedance of the avalanche photodiode 11 is significantly reduced, thereby absorbing and reducing the overcurrent flowing through the resistive element R. Therefore, the resistance element R can be protected and the resistance of the resistance element R can be improved, so that the first protection circuit 21 can be protected and the resistance of the photodetector 1 against overcurrent can be improved.

[0068] 1 to 3, in the photodetector 1, the first conductor 1141 is disposed opposite the second conductor 1142, which is electrically connected to a fixed potential (second fixed voltage) Vc, via the insulator 115. The first conductor 1141, the insulator 115, and the second conductor 1142 form a capacitance element C that protects the resistance element R against overcurrent. With the photodetector 1 configured in this manner, the capacitance element C can absorb and reduce the overcurrent flowing through the resistance element R of the first protection circuit 21. This protects the resistance element R and improves the resistance of the resistance element R, thereby protecting the first protection circuit 21 and improving the resistance of the photodetector 1 against overcurrent.

[0069] 3 , in the photodetector 1, when viewed in the thickness direction of the resistive element R (in a plan view), the first conductor 1141 is disposed so as to overlap the resistive element R. According to the photodetector 1 configured in this manner, the first conductor 1141, i.e., the capacitive element C, can be disposed within the area occupied by the resistive element R, thereby improving the area utilization efficiency.

[0070] 2 and 3 , in the photodetector 1, the first conductor 1141 is electrically connected in parallel to the middle portion in the resistor length direction of the resistive element R. According to the photodetector 1 configured in this manner, it is possible to absorb and reduce the overcurrent flowing through the resistive element R in the first protection circuit 21 in an optimal region for improving the withstand capability of the resistive element R.

[0071] Furthermore, as shown in FIGS. 1 to 3 , the distance measurement system 6 includes a photodetector 1 and a circuit device 5. The photodetector 1 includes an avalanche photodiode 11, a protection circuit 2, and a first conductor 1141. The avalanche photodiode 11 has an anode region to which an anode voltage Vsp is applied, multiplying carriers generated by incident photons. The protection circuit 2 includes a first protection circuit 21. The first protection circuit 21 is electrically connected in series to the cathode region of the avalanche photodiode 11 and includes a resistive element R that protects the readout circuit 3 against overcurrent. The first conductor 1141 is electrically connected in parallel to the resistive element R. Meanwhile, the circuit device 5 includes an internal circuit and a time measurement circuit 4. The internal circuit constitutes the readout circuit 3. The readout circuit 3 is electrically connected to the avalanche photodiode 11 through the protection circuit 2 and reads out the multiplied carriers. The time measurement circuit 4 is electrically connected to the readout circuit 3 and measures the time of flight of light. According to the distance measurement system 6 configured in this manner, as described above, it is possible to improve the resistance of the photodetector 1 to overcurrent.

[0072] 4, a photodetector 1 and a ranging system 6 according to a second embodiment of the present disclosure will be described. The second embodiment describes an example in which the configurations of the resistive element R and the capacitive element C of the protection circuit 2 are changed in the photodetector 1 and ranging system 6 according to the first embodiment. Note that in the second embodiment and the subsequent embodiments, components that are the same as or substantially the same as the components of the photodetector 1 and ranging system 6 according to the first embodiment are denoted by the same reference numerals, and duplicated descriptions will be omitted.

[0073] [Device Configuration of Photodetector 1 and Distance Measuring System 6] FIG. 4 shows an example of a planar configuration of the resistive element R and the capacitive element C of the protection circuit 2 disposed in the photodetector 1 according to the second embodiment.

[0074] As shown in FIG. 4 , the photodetector 1 includes a resistive element R and a capacitive element C in the first protection circuit 21 of the protection circuit 2, similar to the photodetector 1 and ranging system 6 according to the first embodiment. A plurality of first conductors 1141, serving as one electrode of the capacitive element C, are arranged in the resistance length direction of the resistive element R. More specifically, the first conductors 1141 are electrically connected in parallel at regular intervals from one end of the resistive element R to the other end in the resistance length direction, and a plurality of the first conductors 1141 are arranged. While the number of first conductors 1141 is not limited, three first conductors 1141 are arranged here. In the second embodiment, one end of each of the plurality of first conductors 1141 is connected to the resistive element R at an end opposite to the direction of arrow Y. The other end of each of the plurality of first conductors 1141 extends in the meandering direction in the direction of arrow Y.

[0075] Second conductors 1142 (see FIG. 2 ), not shown, are arranged overlapping each of the plurality of first conductors 1141 with insulators 115 interposed therebetween, thereby constructing a capacitance element C. A plurality of second conductors 1142 may be arranged corresponding to each of the plurality of first conductors 1141, or one second conductor 1142 may be arranged corresponding to the plurality of first conductors 1141.

[0076] The other components are the same as or substantially the same as the components of the light detection device 1 and distance measurement system 6 according to the first embodiment, and therefore a duplicated description will be omitted.

[0077] [Effects] As described above, the photodetector 1 and ranging system 6 according to the second embodiment can provide effects similar to those provided by the photodetector 1 and ranging system 6 according to the first embodiment.

[0078] 4 , in the photodetector 1, in the first protection circuit 21, a plurality of first conductors 1141 are arranged in the resistance length direction of the resistive element R. With the photodetector 1 configured in this manner, the overcurrent flowing through the resistive element R is absorbed in stages in the resistance length direction, and the overcurrent can be reduced in stages. This protects the resistive element R and improves the resistance of the resistive element R, thereby protecting the first protection circuit 21 and improving the resistance of the photodetector 1 against overcurrent.

[0079] 5, a photodetector 1 and a ranging system 6 according to a third embodiment of the present disclosure will be described. The third embodiment describes an example in which the configurations of the resistive element R and the capacitive element C of the protection circuit 2 in the photodetector 1 and ranging system 6 according to the second embodiment are changed.

[0080] [Device Configuration of Photodetector 1 and Distance Measuring System 6] FIG. 5 shows an example of a planar configuration of the resistive element R and the capacitive element C of the protection circuit 2 disposed in the photodetector 1 according to the third embodiment.

[0081] As shown in FIG. 5, the photodetector 1 includes a resistive element R and a capacitive element C in the first protection circuit 21 of the protection circuit 2, similar to the photodetector 1 and distance measuring system 6 according to the second embodiment.

[0082] The resistor element R is divided into multiple parts in the resistor length direction. Detailed explanation follows. While the number of divisions is not limited, the resistor element R has five divided resistor elements R1 to R5, each with an equal resistance length, extending in the direction of the arrow Y. The divided resistor elements R1 to R5 are arranged in parallel in a plan view and sequentially arranged in the direction of the arrow X.

[0083] On the other hand, a plurality of first conductors 1141 are arranged, similar to the first conductors 1141 of the photodetector 1 according to the second embodiment. The first conductors 1141 electrically connect the divided resistor elements R1 to R5, each divided into a plurality of resistor elements, in series. A detailed explanation follows. One end of the divided resistor element R1 is electrically connected to the avalanche photodiode 11. The other end of the divided resistor element R1 is connected to one end of the divided resistor element R2 via the first conductor 1141. Similarly, the other end of the divided resistor element R2 is connected to one end of the divided resistor element R3 via the first conductor 1141. The other end of the divided resistor element R3 is connected to one end of the divided resistor element R4 via the first conductor 1141. The other end of the divided resistor element R4 is connected to one end of the divided resistor element R5 via the first conductor 1141. The other end of the dividing resistor element R5 is connected to the second protection circuit 22.

[0084] The first conductors 1141 connecting the dividing resistor elements R1 to R5 are arranged to extend along the meandering direction in the direction of arrow Y or in the opposite direction.

[0085] The other components are the same as or substantially the same as the components of the light detection device 1 and distance measurement system 6 according to the first embodiment, and therefore a duplicated description will be omitted.

[0086] [Effects] As described above, the light detection device 1 and ranging system 6 according to the third embodiment can provide effects similar to those obtained by the light detection device 1 and ranging system 6 according to the second embodiment.

[0087] 6, a photodetector 1 and a ranging system 6 according to a fourth embodiment of the present disclosure will be described. The fourth embodiment describes an example in which the configurations of the resistive element R and the capacitive element C of the protection circuit 2 in the photodetector 1 and ranging system 6 according to the second embodiment are changed.

[0088] [Device Configuration of Photodetector 1 and Distance Measuring System 6] FIG. 6 shows an example of a planar configuration of the resistive element R and the capacitive element C of the protection circuit 2 disposed in the photodetector 1 according to the fourth embodiment.

[0089] As shown in FIG. 6, the photodetector 1 includes a resistive element R and a capacitive element C in the first protection circuit 21 of the protection circuit 2, similar to the photodetector 1 and distance measuring system 6 according to the second embodiment.

[0090] Similar to the first conductors 1141 of the photodetector 1 according to the second embodiment described above, a plurality of first conductors 1141 serving as one electrode of the capacitance element C are arranged in the resistance length direction of the resistance element R. This will be explained in detail. Here, six first conductors 1141 are arranged. Each of the first conductors 1141 is electrically connected in parallel to the resistance element R at the center position in the extension direction, which is the direction of the arrow Y.

[0091] The other components are the same as or substantially the same as the components of the light detection device 1 and distance measurement system 6 according to the second embodiment, and therefore a duplicated description will be omitted.

[0092] [Effects] As described above, the optical detection device 1 and ranging system 6 according to the fourth embodiment can provide effects similar to those obtained by the optical detection device 1 and ranging system 6 according to the second embodiment.

[0093] 7, a photodetector 1 and a ranging system 6 according to a fifth embodiment of the present disclosure will be described. The fifth embodiment describes an example in which the configurations of the resistive element R and the capacitive element C of the protection circuit 2 in the photodetector 1 and ranging system 6 according to the fourth embodiment are changed.

[0094] [Device Configuration of Photodetector 1 and Distance Measuring System 6] FIG. 7 shows an example of a planar configuration of the resistive element R and the capacitive element C of the protection circuit 2 disposed in the photodetector 1 according to the fifth embodiment.

[0095] As shown in FIG. 7, the photodetector 1 includes a resistive element R and a capacitive element C in the first protection circuit 21 of the protection circuit 2, similar to the photodetector 1 and distance measuring system 6 according to the fourth embodiment.

[0096] In the fifth embodiment, the capacitance element C includes a capacitance element C1 and a capacitance element C2 electrically connected in series to the capacitance element C1. A detailed description will be given below. The capacitance element C1 includes a first conductor 1141, an insulator 115, and a second conductor 1142. On the other hand, the capacitance element C2 includes a second conductor 1142 further shared as one electrode, an insulator 115, and a third conductor 1143 as the other electrode. The third conductor 1143 is formed by a wiring 114 stacked on the side of the second conductor 1142 opposite the first conductor 1141 with the insulator 115 interposed therebetween. In other words, the capacitance element C is formed by a multilayer conductor in which the first conductor 1141, the second conductor 1142, and the third conductor 1143 are stacked.

[0097] The other components are the same as or substantially the same as the components of the light detection device 1 and distance measurement system 6 according to the fourth embodiment, and therefore a duplicated description will be omitted.

[0098] [Effects] As described above, the optical detection device 1 and ranging system 6 according to the fifth embodiment can provide effects similar to those obtained by the optical detection device 1 and ranging system 6 according to the second embodiment.

[0099] 8, a photodetector 1 and a ranging system 6 according to a sixth embodiment of the present disclosure will be described. The sixth embodiment describes an example in which the configurations of the resistive element R and the capacitive element C of the protection circuit 2 in the photodetector 1 and ranging system 6 according to the third embodiment are changed.

[0100] [Device Configuration of Photodetection Device 1 and Distance Measuring System 6] FIG. 8 shows an example of the planar configuration of the pixel 10, the resistive element R and the capacitive element C of the protection circuit 2 arranged in the photodetection device 1 according to the sixth embodiment.

[0101] As shown in Figure 8, the photodetector 1 has a resistive element R and a capacitive element C in the first protection circuit 21 of the protection circuit 2, similar to the photodetector 1 and ranging system 6 of the first and third embodiments.

[0102] The resistor element R is arranged so as to overlap the pixel 10 in plan view. More detailed explanation follows. The resistor element R is arranged in an insulating separator 102 that surrounds the periphery of the pixel 10, and is arranged so as to overlap the avalanche photodiode 11. Here, the resistor element R includes four divided resistor elements R1 to R4 that extend along the periphery of the pixel 10.

[0103] The dividing resistor elements R1 and R3 face each other in the direction of the arrow X and extend in the direction of the arrow Y. The dividing resistor elements R2 and R4 face each other in the direction of the arrow Y and extend in the direction of the arrow X.

[0104] One end of the dividing resistor R1 is electrically connected to the avalanche photodiode 11 through wiring 114. The other end of the dividing resistor R1 is connected to one end of the dividing resistor R2 via a first conductor 1141. Similarly, the other end of the dividing resistor R2 is connected to one end of the dividing resistor R3 via the first conductor 1141. The other end of the dividing resistor R3 is connected to one end of the dividing resistor R4 via the first conductor 1141. The other end of the dividing resistor R4 is connected to the second protection circuit 22.

[0105] The first conductors 1141 that connect the divided resistor elements R1 to R4 respectively constitute a capacitance element C.

[0106] The other components are the same as or substantially the same as the components of the light detection device 1 and distance measurement system 6 according to the third embodiment, and therefore a duplicated description will be omitted.

[0107] [Effects] As described above, the optical detection device 1 and ranging system 6 according to the sixth embodiment can provide effects similar to those obtained by the optical detection device 1 and ranging system 6 according to the third embodiment.

[0108] 8, in the photodetector 1, the resistive element R and the capacitive element C are arranged so as to overlap the pixel 10 in plan view. According to the photodetector 1 configured in this manner, the resistive element R and the capacitive element C can be arranged within the area occupied by the pixel 10, thereby improving the area utilization efficiency.

[0109] 9, a light detection device 1 and a ranging system 6 according to a seventh embodiment of the present disclosure will be described. In the seventh embodiment, an example will be described in which the light detection device 1 and the ranging system 6 according to the fourth embodiment are combined with the light detection device 1 and the ranging system 6 according to the sixth embodiment.

[0110] [Device Configuration of Photodetection Device 1 and Distance Measuring System 6] FIG. 9 shows an example of the planar configuration of the pixel 10, the resistive element R and the capacitive element C of the protection circuit 2 arranged in the photodetection device 1 according to the seventh embodiment.

[0111] As shown in FIG. 9, the photodetector 1 includes a resistive element R and a capacitive element C in the first protection circuit 21 of the protection circuit 2, similar to the photodetector 1 and distance measuring system 6 according to the sixth embodiment.

[0112] The resistor R is disposed so as to overlap the pixel 10 in plan view. The resistor R is disposed in an insulating separator 102 that surrounds the periphery of the pixel 10, and is disposed so as to overlap the avalanche photodiode 11. In this example, the resistor R extends along the periphery of the pixel 10. One end of the resistor R1 is electrically connected to the avalanche photodiode 11 through a wiring 114. The other end of the resistor R is connected to the second protection circuit 22.

[0113] Similar to the first conductors 1141 according to the fourth embodiment, a plurality of first conductors 1141 serving as one electrode of the capacitance element C are arranged in the resistance length direction of the resistance element R. Each of the first conductors 1141 extends toward the center of the pixel 10 to increase the capacitance area. As described above, the first conductor 1141 includes the insulator 115 and the second conductor 1142 (not shown) (see FIG. 2 ), and constitutes the capacitance element C.

[0114] The other components are the same as or substantially the same as the components of the light detection device 1 and distance measurement system 6 according to the fourth and sixth embodiments, and therefore a duplicated description will be omitted.

[0115] [Effects] As described above, the optical detection device 1 and ranging system 6 according to the seventh embodiment can achieve an effect that combines the effects obtained by the optical detection device 1 and ranging system 6 according to the fourth embodiment and the effects obtained by the optical detection device 1 and ranging system 6 according to the sixth embodiment.

[0116] 10 and 11 , a photodetector 1 and a ranging system 6 according to an eighth embodiment of the present disclosure will be described. The eighth embodiment describes an example in which the configurations of the resistive element R and the capacitive element C of the protection circuit 2 in the photodetector 1 and ranging system 6 according to the sixth embodiment are changed.

[0117] [Device Configuration of Photodetection Device 1 and Distance Measuring System 6] Fig. 10 shows an example of a vertical cross-sectional configuration of the pixel 10 and the resistance element R and capacitance element C of the protection circuit 2 arranged in the photodetection device 1 according to the eighth embodiment. Fig. 11 shows an example of a planar configuration of the pixel 10 and the resistance element R and capacitance element C of the protection circuit 2.

[0118] As shown in Figures 10 and 11, the photodetector 1 has a resistive element R and a capacitive element C in the first protection circuit 21 of the protection circuit 2, similar to the photodetector 1 and ranging system 6 of the sixth embodiment.

[0119] In plan view, the resistor element R includes four divided resistor elements R1 to R4 extending along the periphery of the pixel 10. Here, as described above, the divided resistor element R1 is formed of, for example, polycrystalline Si, and one end of the divided resistor element R1 is directly and electrically connected to the cathode region of the avalanche photodiode 11.

[0120] The other components are the same as or substantially the same as the components of the light detection device 1 and distance measurement system 6 according to the sixth embodiment, and therefore a duplicated description will be omitted.

[0121] [Effects] As described above, the optical detection device 1 and ranging system 6 according to the eighth embodiment can provide effects similar to those obtained by the optical detection device 1 and ranging system 6 according to the sixth embodiment.

[0122] 12 and 13 , a light detection device 1 and a ranging system 6 according to a ninth embodiment of the present disclosure will be described. In the ninth embodiment, an example will be described in which the light detection device 1 and the ranging system 6 according to the fifth embodiment are combined with the light detection device 1 and the ranging system 6 according to the seventh embodiment.

[0123] [Device Configuration of Photodetection Device 1 and Distance Measuring System 6] Fig. 12 shows an example of a vertical cross-sectional configuration of the pixel 10 and the resistance element R and capacitance element C of the protection circuit 2 arranged in the photodetection device 1 according to the ninth embodiment. Fig. 13 shows an example of a planar configuration of the pixel 10 and the resistance element R and capacitance element C of the protection circuit 2.

[0124] As shown in Figures 12 and 13, the photodetector 1 has a resistive element R and a capacitive element C in the first protection circuit 21 of the protection circuit 2, similar to the photodetector 1 and ranging system 6 of the seventh embodiment.

[0125] Similarly to the capacitive element C according to the fifth embodiment, the capacitive element C includes a capacitive element C1 and a capacitive element C2 electrically connected in series to the capacitive element C1. That is, the capacitive element C is formed of a multilayer conductor in which a first conductor 1141, a second conductor 1142, and a third conductor 1143 are stacked.

[0126] The other components are the same or substantially the same as the components of the light detection device 1 and distance measurement system 6 according to the fifth and seventh embodiments, and therefore a duplicated description will be omitted.

[0127] [Effects] As described above, the optical detection device 1 and ranging system 6 according to the ninth embodiment can achieve an effect that combines the effects obtained by the optical detection device 1 and ranging system 6 according to the fifth embodiment and the effects obtained by the optical detection device 1 and ranging system 6 according to the seventh embodiment.

[0128] 10. Tenth Embodiment A photodetector 1 and a ranging system 6 according to a tenth embodiment of the present disclosure will be described with reference to Fig. 14. The tenth embodiment describes an example in which the configurations of the resistive element R and the capacitive element C of the protection circuit 2 in the photodetector 1 and ranging system 6 according to the first embodiment are changed.

[0129] [Device Configuration of Photodetection Device 1 and Distance Measuring System 6] FIG. 14 shows an example of a vertical cross-sectional configuration of a pixel 10, a resistive element R and a capacitive element C of a protection circuit 2 arranged in a photodetection device 1 according to the tenth embodiment.

[0130] As shown in FIG. 14, the photodetector 1 includes a resistive element R and a capacitive element C in the first protection circuit 21 of the protection circuit 2, similar to the photodetector 1 and distance measuring system 6 according to the sixth embodiment.

[0131] As described above, the resistor element R is formed by the wiring 113. Here, a metal (metallic resistance material) is used for the wiring 113. For example, TaO ｘ , TaSiO ｘ etc. can be used practically.

[0132] The other components are the same as or substantially the same as the components of the light detection device 1 and distance measurement system 6 according to the first embodiment, and therefore a duplicated description will be omitted.

[0133] [Effects] As described above, the optical detection device 1 and ranging system 6 according to the tenth embodiment can provide effects similar to those provided by the optical detection device 1 and ranging system 6 according to the first embodiment.

[0134] 11. Eleventh embodiment A photodetector 1 and a ranging system 6 according to an eleventh embodiment of the present disclosure will be described with reference to Fig. 15 and Fig. 16. The eleventh embodiment describes an example in which the configurations of the resistive element R and the capacitive element C of the protection circuit 2 in the photodetector 1 and ranging system 6 according to the first embodiment are changed.

[0135] [Device Configuration of Photodetection Device 1 and Distance Measuring System 6] Fig. 15 shows an example of the circuit configuration of a part of the photodetection device 1 and distance measuring system 6 according to the eleventh embodiment. Fig. 16 shows an example of the vertical cross-sectional configuration of the pixel 10, the resistive element R and the capacitive element C of the protection circuit 2 arranged in the photodetection device 1.

[0136] As shown in Figures 15 and 16, the photodetector 1 has a resistive element R and a capacitive element C in the first protection circuit 21 of the protection circuit 2, similar to the photodetector 1 and ranging system 6 of the first embodiment.

[0137] In the eleventh embodiment, the resistor R is formed of a transistor resistor. Here, for example, a p-type IGFET is used as the transistor resistor. The p-type IGFET includes a gate insulating film 118 disposed in an n-type well region 116, a wiring 113 as a gate electrode, and a pair of p-type semiconductor regions 117 as a source region and a drain region. Note that, for example, an n-type IGFET may also be used as the transistor resistor.

[0138] On the other hand, the capacitance element C is constructed to include at least a capacitance C3 generated between the wiring (gate electrode) 113 and one of the pair of p-type semiconductor regions 117, and a capacitance C4 generated between the wiring (gate electrode) 113 and the other of the pair of p-type semiconductor regions 117.

[0139] The other components are the same as or substantially the same as the components of the light detection device 1 and distance measurement system 6 according to the first embodiment, and therefore a duplicated description will be omitted.

[0140] [Effects] As described above, the photodetector 1 and ranging system 6 according to the eleventh embodiment can provide effects similar to those provided by the photodetector 1 and ranging system 6 according to the first embodiment.

[0141] 12. Twelfth Embodiment A photodetector 1 and a ranging system 6 according to a twelfth embodiment of the present disclosure will be described with reference to Fig. 17. The twelfth embodiment describes an example in which the configurations of the resistive element R and the capacitive element C of the protection circuit 2 in the photodetector 1 and ranging system 6 according to the first embodiment are changed.

[0142] [Device Configuration of the Light Detecting Device 1 and Distance Measuring System 6] FIG. 17 shows an example of a circuit configuration of a part of the light detecting device 1 and distance measuring system 6 according to the twelfth embodiment.

[0143] As shown in FIG. 17, the photodetector 1 includes a resistive element R and a capacitive element C in the first protection circuit 21 of the protection circuit 2, similar to the photodetector 1 and distance measuring system 6 according to the first embodiment.

[0144] In the twelfth embodiment, the pixels 10 having the avalanche photodiodes 11 are disposed on a base (first base) 101. The first protection circuit 21 of the protection circuit 2 is disposed on a base (second base) 501. As described above, the first protection circuit 21 includes a resistive element R and a capacitive element C. Here, the photodetector 1 according to the twelfth embodiment is constructed including the base 101 having the pixels 10 and a part of the base 501 that corresponds to the first protection circuit 21. The ranging system 6 includes the first protection circuit 21.

[0145] The other components are the same as or substantially the same as the components of the light detection device 1 and distance measurement system 6 according to the first embodiment, and therefore a duplicated description will be omitted.

[0146] [Effects] As described above, the photodetector 1 and ranging system 6 according to the twelfth embodiment can provide effects similar to those provided by the photodetector 1 and ranging system 6 according to the first embodiment.

[0147] 13. Thirteenth Embodiment A photodetector 1 and a ranging system 6 according to a thirteenth embodiment of the present disclosure will be described with reference to Fig. 18. The thirteenth embodiment describes an example in which the configurations of the resistive element R and the capacitive element C of the protection circuit 2 in the photodetector 1 and ranging system 6 according to the first embodiment are changed.

[0148] [Device Configuration of the Light Detecting Device 1 and Distance Measuring System 6] FIG. 18 shows an example of a circuit configuration of a part of the light detecting device 1 and distance measuring system 6 according to the thirteenth embodiment.

[0149] As shown in FIG. 18, the photodetector 1 includes a resistive element R and a capacitive element C in the first protection circuit 21 of the protection circuit 2, similar to the photodetector 1 and distance measuring system 6 according to the first embodiment.

[0150] In the thirteenth embodiment, a first protection circuit 21 of the protection circuit 2 is disposed across both the base (first base) 101 and the base (second base) 501. A detailed explanation will be given below. The resistance element R of the first protection circuit 21 is divided into a divided resistance element R1 and a divided resistance element R2. The divided resistance element R1 is disposed on the base 101. The divided resistance element R2 is electrically connected in series to the divided resistance element R1 and disposed on the base 501.

[0151] Furthermore, the capacitance element C is electrically connected in parallel to the dividing resistor element R1. Note that the capacitance element C may be electrically connected in parallel to the dividing resistor element R2, or to both the dividing resistor element R1 and the dividing resistor element R2.

[0152] Here, the photodetector 1 of the thirteenth embodiment is constructed to include a base 101 including a first protection circuit 21 and a part of a base 501, similar to the photodetector 1 of the twelfth embodiment described above.

[0153] The other components are the same as or substantially the same as the components of the light detection device 1 and distance measurement system 6 according to the first embodiment, and therefore a duplicated description will be omitted.

[0154] [Effects] As described above, the photodetector 1 and ranging system 6 according to the thirteenth embodiment can provide effects similar to those provided by the photodetector 1 and ranging system 6 according to the first embodiment.

[0155] 19 will be used to describe a photodetector 1 and a ranging system 6 according to a fourteenth embodiment of the present disclosure. The fourteenth embodiment describes an example in which the configurations of the resistive element R and the capacitive element C of the protection circuit 2 in the photodetector 1 and ranging system 6 according to the first embodiment are changed.

[0156] [Device Configuration of the Light Detecting Device 1 and Distance Measuring System 6] FIG. 19 shows an example of a circuit configuration of a part of the light detecting device 1 and distance measuring system 6 according to the fourteenth embodiment.

[0157] As shown in FIG. 19, the photodetector 1 includes a resistive element R and a capacitive element C in the first protection circuit 21 of the protection circuit 2, similar to the photodetector 1 and distance measuring system 6 according to the first embodiment.

[0158] In the fourteenth embodiment, similarly to the avalanche photodiode 11 of the photodetector 1 according to the first embodiment, the resistor element R of the protection circuit 2 is electrically connected to the cathode region of the avalanche photodiode 11. Here, the cathode region is an n-type semiconductor region. On the other hand, the resistor element R is formed of polycrystalline Si doped with p-type impurities. In other words, the cathode region and the resistor element R have different polarities.

[0159] The other components are the same as or substantially the same as the components of the light detection device 1 and distance measurement system 6 according to the first embodiment, and therefore a duplicated description will be omitted.

[0160] [Effects] As described above, the optical detection device 1 and ranging system 6 according to the fourteenth embodiment can provide effects similar to those obtained by the optical detection device 1 and ranging system 6 according to the first embodiment.

[0161] 15. Fifteenth embodiment A photodetector 1 and a ranging system 6 according to a fifteenth embodiment of the present disclosure will be described with reference to Fig. 20. The fifteenth embodiment describes an example in which the configurations of the resistive element R and the capacitive element C of the protection circuit 2 in the photodetector 1 and ranging system 6 according to the first embodiment are changed.

[0162] [Device Configuration of the Photodetector 1 and Distance Measuring System 6] FIG. 20 shows an example of a circuit configuration of a part of the photodetector 1 and distance measuring system 6 according to the fifteenth embodiment.

[0163] As shown in FIG. 20, the photodetector 1 includes a resistive element R and a capacitive element C in the first protection circuit 21 of the protection circuit 2, similar to the photodetector 1 and distance measuring system 6 according to the first embodiment.

[0164] In the fifteenth embodiment, unlike the avalanche photodiode 11 of the photodetector 1 according to the first embodiment, the resistance element R of the protection circuit 2 is electrically connected to the anode region of the avalanche photodiode 11. Here, the anode region is a p-type semiconductor region.

[0165] The cathode region is supplied with a cathode voltage Vsp from a cathode power line VLsp. The cathode voltage Vsp is a large positive voltage that generates avalanche multiplication, or in other words, a fixed voltage (first fixed voltage) equal to or higher than a predetermined breakdown voltage. The cathode voltage Vsp is, for example, a voltage of 20 V or higher.

[0166] On the other hand, the resistor element R is made of polycrystalline Si doped with n-type impurities. That is, the anode region and the resistor element R have different polarities.

[0167] The first clamp element Tc1 of the second protection circuit 22 is composed of an n-type IGFET.

[0168] The other components are the same as or substantially the same as the components of the light detection device 1 and distance measurement system 6 according to the first embodiment, and therefore a duplicated description will be omitted.

[0169] [Effects] As described above, the photodetector 1 and ranging system 6 according to the fifteenth embodiment can achieve the same effects as those achieved by the photodetector 1 and ranging system 6 according to the first embodiment. 16. Sixteenth Embodiment A photodetector 1 and ranging system 6 according to a sixteenth embodiment of the present disclosure will be described using FIG. 21 . The sixteenth embodiment describes an example in which the configurations of the resistive element R and the capacitive element C of the protection circuit 2 are changed in the photodetector 1 and ranging system 6 according to the fifteenth embodiment.

[0170] [Device Configuration of the Photodetector 1 and Distance Measuring System 6] FIG. 21 shows an example of a circuit configuration of a part of the photodetector 1 and distance measuring system 6 according to the sixteenth embodiment.

[0171] As shown in FIG. 21, the photodetector 1 includes a resistive element R and a capacitive element C in the first protection circuit 21 of the protection circuit 2, similar to the photodetector 1 and distance measuring system 6 according to the fifteenth embodiment.

[0172] In the sixteenth embodiment, similarly to the avalanche photodiode 11 of the photodetector 1 according to the fifteenth embodiment, the resistance element R of the protection circuit 2 is electrically connected to the anode region of the avalanche photodiode 11. Here, the anode region is a p-type semiconductor region.

[0173] On the other hand, the resistor element R is made of polycrystalline Si doped with p-type impurities. That is, the anode region and the resistor element R have the same polarity.

[0174] The first clamp element Tc1 of the second protection circuit 22 is composed of an n-type IGFET.

[0175] The other components are the same as or substantially the same as the components of the light detection device 1 and distance measurement system 6 according to the fifteenth embodiment, and therefore a duplicated description will be omitted.

[0176] [Effects] As described above, the photodetector 1 and ranging system 6 according to the 16th embodiment can provide effects similar to those obtained by the photodetector 1 and ranging system 6 according to the 15th embodiment.

[0177] 17. Application Examples to Mobile Bodies The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of mobile body, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, or a robot.

[0178] FIG. 22 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile object control system to which the technology according to the present disclosure can be applied.

[0179] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 22, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. Also shown as functional components of the integrated control unit 12050 are a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (Interface) 12053.

[0180] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating a braking force of the vehicle.

[0181] The body system control unit 12020 controls the operation of various devices equipped in the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as headlamps, backup lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves transmitted from a portable device that serves as a key or signals from various switches can be input to the body system control unit 12020. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0182] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture images outside the vehicle and receives the captured images. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for people, cars, obstacles, signs, characters on the road surface, etc. based on the received images.

[0183] 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 can output the electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0184] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

[0185] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, steering mechanism, or braking device based on the information inside and outside the vehicle acquired by the outside-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the distance between vehicles, maintaining vehicle speed, vehicle collision warning, vehicle lane departure warning, etc.

[0186] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle obtained by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0187] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the outside information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside information detection unit 12030, and perform cooperative control aimed at preventing glare, such as switching from high beams to low beams.

[0188] The audio / video output unit 12052 transmits at least one of audio and video output signals to an output device capable of visually or audibly notifying information to vehicle occupants or the outside of the vehicle. In the example of Fig. 22, the output devices are exemplified by an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

[0189] FIG. 23 is a diagram showing an example of the installation position of the imaging unit 12031.

[0190] In FIG. 23, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0191] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided on the front nose and the imaging unit 12105 provided on the top of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 provided on the top of the windshield inside the vehicle cabin is mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0192] 23 shows an example of the imaging ranges of the imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, by overlaying the image data captured by the imaging units 12101 to 12104, an overhead image of the vehicle 12100 viewed from above can be obtained.

[0193] At least one of the image capturing units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image capturing units 12101 to 12104 may be a stereo camera made up of multiple image capturing elements, or may be an image capturing element having pixels for phase difference detection.

[0194] For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 can calculate the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100), thereby extracting as a preceding vehicle, in particular, the three-dimensional object that is the closest three-dimensional object on the path of the vehicle 12100 and traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or higher). Furthermore, the microcomputer 12051 can set a vehicle-to-vehicle distance to be maintained in advance in front of the preceding vehicle, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. In this way, cooperative control can be performed for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation.

[0195] For example, the microcomputer 12051 classifies and extracts three-dimensional object data regarding three-dimensional objects into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from the imaging units 12101 to 12104, and can use the data for automatic obstacle avoidance. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 then determines a collision risk that indicates the risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drive system control unit 12010.

[0196] At least one of the image capturing units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether a pedestrian is present in the images captured by the image capturing units 12101 to 12104. Such pedestrian recognition is performed, for example, by extracting feature points from the images captured by the image capturing units 12101 to 12104 as infrared cameras and performing pattern matching on a series of feature points that indicate the outline of an object to determine whether the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the image capturing units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular outline on the recognized pedestrian for emphasis. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating the pedestrian at a desired position.

[0197] The above describes an example of a vehicle control system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to the imaging unit 12031 among the components described above. By applying the technology according to the present disclosure to the imaging unit 12031, it is possible to further improve the resistance of the resistive element against excessive voltage and improve the characteristics of the protection circuit.

[0198] 18. Other Embodiments The present technology is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present technology. For example, among the light detection devices and distance measurement systems according to the first to sixteenth embodiments, the light detection devices and distance measurement systems according to two or more of the above-described embodiments may be combined.

[0199] A photodetector according to a first embodiment of the present disclosure includes an avalanche photodiode having an anode region and a cathode region to which a first fixed voltage is applied, the avalanche photodiode multiplying carriers generated by incident photons; a protection circuit electrically connected in series to the other of the anode region and the cathode region and having a resistive element for protecting the internal circuit against overcurrent; and a first conductor electrically connected in parallel to the resistive element. With this photodetector configured as described above, when a greater amount of photons than expected is incident on the avalanche photodiode, the resistive element can absorb and reduce the overcurrent that flows through the resistive element. This protects the resistive element and improves its withstand voltage, thereby protecting the protection circuit and improving the withstand voltage of the photodetector.

[0200] In a photodetector according to a second embodiment of the present disclosure, the first conductor of the photodetector according to the first embodiment is disposed opposite a second conductor electrically connected to a second fixed voltage, with an insulator interposed therebetween. Furthermore, in the photodetector, the first conductor, the insulator, and the second conductor form a capacitive element that protects the resistive element against overcurrent. With a photodetector configured in this manner, the capacitive element can absorb and reduce overcurrent flowing through the resistive element. This protects the resistive element and improves its withstand capability, thereby protecting the protection circuit and improving the withstand capability of the photodetector against overcurrent.

[0201] In a photodetector according to a third embodiment of the present disclosure, in the photodetector according to the first embodiment, the resistive element is formed of polycrystalline silicon, metal, or an insulated gate field effect transistor. With this photodetector configured in this manner, regardless of the material or structure of the resistive element, the capacitive element can absorb and reduce the overcurrent flowing through the resistive element. This protects the resistive element and improves its withstand capability, thereby protecting the protection circuit and improving the withstand capability of the photodetector against overcurrent.

[0202] In a photodetector according to a fourth embodiment of the present disclosure, the polarity of the resistive element in the photodetector according to the first embodiment is the same as or different from the polarity of the other of the anode region and the cathode region of the avalanche photodiode. With this photodetector configured in this manner, the capacitive element can absorb and reduce the overcurrent flowing through the resistive element, regardless of the polarities of the avalanche photodiode and the resistive element. This protects the resistive element and improves its withstand capability, thereby protecting the protection circuit and improving the withstand capability of the photodetector against overcurrent.

[0203] A ranging system according to a fifth embodiment of the present disclosure includes a photodetector and a circuit device. The photodetector includes an avalanche photodiode having a first fixed voltage applied to one of its anode and cathode regions, which multiplies carriers generated by incident photons; a protection circuit electrically connected in series to the other of the anode and cathode regions and having a resistive element for protecting the internal circuit against overcurrent; and a first conductor electrically connected in parallel to the resistive element. The circuit device includes an internal circuit electrically connected to the avalanche photodiode through the protection circuit and constituting a readout circuit for reading out the multiplied carriers; and a time measurement circuit electrically connected to the internal circuit and measuring the time of flight of light. With this ranging system, the photodetector's tolerance to overcurrent can be improved, similar to the photodetector according to the first embodiment.

[0204] <Configuration of the Present Technology> The present technology has the following configuration: According to the present technology having the following configuration, it is possible to protect the protection circuit and improve the overcurrent resistance of the photodetector.

[0205] (1) A photodetector comprising: an avalanche photodiode having an anode region and a cathode region to which a first fixed voltage is applied, and which multiplies carriers generated by incident photons; a protection circuit electrically connected in series to the other of the anode region and the cathode region and having a resistive element that protects an internal circuit against overcurrent; and a first conductor electrically connected in parallel to the resistive element. (2) The photodetector according to (1), in which the first conductor is disposed opposite a second conductor electrically connected to a second fixed voltage, with an insulator interposed therebetween. (3) The photodetector according to (2), in which the first conductor, the insulator, and the second conductor form a capacitive element that protects the resistive element against overcurrent. (4) The photodetector according to any one of (1) to (3), in which the first conductor is disposed so as to overlap the resistive element when viewed in the thickness direction of the resistive element. (5) The photodetector according to any one of (1) to (4), wherein the first conductor is electrically connected in parallel to an intermediate portion of the resistor element in the resistor length direction. (6) The photodetector according to any one of (1) to (4), wherein a plurality of the first conductors are arranged in the resistor length direction of the resistor element. (7) The photodetector according to any one of (1) to (4), wherein the resistor element is divided into a plurality of pieces in the resistor length direction, and the first conductor electrically connects the divided resistor elements in series. (8) The photodetector according to any one of (1) to (4), wherein the first conductor is connected to the resistor element at its center when viewed in the thickness direction of the resistor element. (9) The photodetector according to any one of (1) to (4), wherein the first conductor forms a capacitive element using multilayer conductors stacked in the thickness direction. (10) The photodetector according to any one of (1) to (9), wherein the resistive element is disposed so as to overlap the avalanche photodiode when viewed in a thickness direction of the resistive element.(11) The photodetector according to any one of (1) to (10), wherein a semiconductor is directly electrically connected to the avalanche photodiode side of the resistance element, or wherein the semiconductor is indirectly electrically connected via a metal body. (12) The photodetector according to any one of (1) to (11), wherein the resistance element is formed containing polycrystalline Si or a metal. (13) The photodetector according to any one of (1) to (11), wherein the resistance element is formed containing an insulated gate field effect transistor. (14) The photodetector according to any one of (1) to (13), comprising: a first base on which the avalanche photodiode is disposed; and a second base on which the first base is stacked and on which the resistance element is disposed. (15) The photodetector according to any one of (1) to (13), comprising a first base on which the avalanche photodiode and the resistance element are disposed. (16) The photodetector according to any one of (1) to (13), comprising a first substrate and a second substrate on which the first substrate is stacked, the avalanche photodiode being disposed on the first substrate, and a portion of the resistive element being disposed on the first substrate and another portion of the resistive element being disposed on the second substrate. (17) The photodetector according to any one of (1) to (16), wherein the polarity of the resistive element is the same as the polarity of the other of the anode region and the cathode region of the avalanche photodiode. (18) The photodetector according to any one of (1) to (16), wherein the polarity of the resistive element is different from the polarity of the other of the anode region and the cathode region of the avalanche photodiode. (19) The photodetector according to any one of (1) to (18), wherein the protection circuit further comprises a clamp element electrically connected in series between the resistive element and the internal circuit.(20) A ranging system comprising a photodetector and a circuit device, wherein the photodetector comprises: an avalanche photodiode having a first fixed voltage applied to one of an anode region and a cathode region, and multiplying carriers generated by incident photons; a protection circuit electrically connected in series to the other of the anode region and the cathode region, and having a resistance element that protects the internal circuit against overcurrent; and a first conductor electrically connected in parallel to the resistance element; and the circuit device comprises: the internal circuit that is electrically connected to the avalanche photodiode through the protection circuit and forms a readout circuit that reads out the multiplied carriers; and a time measurement circuit electrically connected to the internal circuit and that measures the time of flight of light.

[0206] This application claims priority based on Japanese Patent Application No. 2024-036956, filed on March 11, 2024, in the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0207] Those skilled in the art will recognize that various modifications, combinations, subcombinations, and variations may occur depending on design requirements and other factors, and are intended to be within the scope of the appended claims and their equivalents.

Claims

1. A photodetector comprising: an avalanche photodiode having a first fixed voltage applied to one of an anode region and a cathode region, which multiplies carriers generated by incident photons; a protection circuit electrically connected in series to the other of the anode region and the cathode region, which has a resistive element that protects the internal circuitry against overcurrent; and a first conductor electrically connected in parallel to the resistive element.

2. The photodetector according to claim 1, wherein the first conductor is disposed opposite a second conductor electrically connected to a second fixed voltage, with an insulator interposed therebetween.

3. The photodetector according to claim 2, wherein the first conductor, the insulator, and the second conductor form a capacitance element that protects the resistance element against overcurrent.

4. The photodetector according to claim 1, wherein the first conductor is disposed so as to overlap the resistive element when viewed in the thickness direction of the resistive element.

5. The photodetector according to claim 1, wherein the first conductor is electrically connected in parallel to an intermediate portion of the resistor element in the resistor length direction.

6. The photodetector according to claim 1, wherein a plurality of the first conductors are arranged in the resistor length direction of the resistor element.

7. The photodetector according to claim 1, wherein the resistive element is divided into a plurality of pieces in the direction of the resistive length, and the first conductor electrically connects the divided resistive elements in series.

8. The photodetector according to claim 1, wherein the first conductor is connected to the resistive element at its center when viewed in the thickness direction of the resistive element.

9. The photodetector according to claim 1, wherein the first conductor is a capacitive element formed of a multi-layer conductor stacked in the thickness direction.

10. The photodetector according to claim 1, wherein the resistive element is disposed so as to overlap the avalanche photodiode when viewed in the thickness direction of the resistive element.

11. The photodetector according to claim 1, wherein a semiconductor is directly or indirectly electrically connected to the avalanche photodiode side of the resistance element through a metal body.

12. The photodetector according to claim 1, wherein the resistive element is formed of polycrystalline silicon or a metal.

13. The photodetector according to claim 1, wherein the resistive element is formed to include an insulated gate field effect transistor.

14. The photodetector according to claim 1, comprising: a first substrate on which the avalanche photodiode is disposed; and a second substrate on which the first substrate is laminated and on which the resistive element is disposed.

15. The photodetector according to claim 1, further comprising a first substrate on which the avalanche photodiode and the resistive element are disposed.

16. The photodetector according to claim 1, comprising a first substrate and a second substrate on which the first substrate is laminated, the avalanche photodiode being disposed on the first substrate, a portion of the resistive element being disposed on the first substrate, and another portion of the resistive element being disposed on the second substrate.

17. The photodetector device according to claim 1, wherein the polarity of the resistive element is the same as the polarity of the other of the anode region and the cathode region of the avalanche photodiode.

18. The photodetector device according to claim 1, wherein the polarity of the resistive element is different from the polarity of the other of the anode region and the cathode region of the avalanche photodiode.

19. The photodetector device according to claim 1, wherein the protection circuit further comprises a clamp element electrically connected in series between the resistance element and the internal circuit.

20. A ranging system comprising a photodetector and a circuit device, wherein the photodetector comprises: an avalanche photodiode having a first fixed voltage applied to one of an anode region and a cathode region, which multiplies carriers generated by incident photons; a protection circuit electrically connected in series to the other of the anode region and the cathode region, which has a resistive element that protects the internal circuit against overcurrent; and a first conductor electrically connected in parallel to the resistive element; and the circuit device comprises: the internal circuit, electrically connected to the avalanche photodiode through the protection circuit, which constitutes a readout circuit that reads out the multiplied carriers; and a time measurement circuit electrically connected to the internal circuit, which measures the time of flight of light.

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