Light detection device

Abstract

A light detection device according to an embodiment of the present disclosure comprises: a semiconductor substrate that has a first surface and a second surface facing each other and has a plurality of pixels arranged in an array form in an in-plane direction; first impurity regions that each include a first conductivity-type impurity and are provided on the first surface side of the semiconductor substrate substantially at the center of the corresponding pixel; second impurity regions that each include a second conductivity-type impurity formed embedded in the semiconductor substrate in a manner surrounding the corresponding first impurity region; and semiconductor regions that are each provided between the corresponding first impurity region and second impurity region, and have a lower impurity concentration than the peak concentration of the first conductivity-type impurity included in the first impurity region and the peak concentration of the second conductivity-type impurity included in the second impurity region.

Description

Photodetector

[0001] The present disclosure relates to a photodetection device using, for example, an avalanche photodiode.

[0002] For example, Patent Document 1 discloses a semiconductor device in which a laminated layer including a second semiconductor material different from the first semiconductor material is laminated via a transition layer on the light incident surface of a substrate including a first semiconductor material in a plurality of pixels each including an avalanche photodiode element that photoelectrically converts incident light. Non-Patent Document 1 also reports a germanium avalanche photodiode that employs a guard ring or mesa structure to prevent edge breakdown and microplasma.

[0003] International Publication No. 2021 / 261093

[0004] Tosi, Alberto, et al. Germanium and InGaAs / InP SPADs for single-photon detection in the near-infrared. Advanced Photon Counting Techniques II. Vol. 6771. SPIE, 2007.

[0005] Incidentally, there is a demand for an improvement in the dark count rate of photodetectors.

[0006] It would be desirable to provide a photodetector device that is capable of improving the dark count rate.

[0007] A photodetector according to one embodiment of the present disclosure includes a semiconductor substrate having opposing first and second surfaces and including a plurality of pixels arranged in an array in an in-plane direction; a first impurity region containing a first conductivity type impurity provided approximately at the center of the pixel on the first surface side of the semiconductor substrate; a second impurity region containing a second conductivity type impurity formed and embedded in the semiconductor substrate so as to surround the first impurity region; and a semiconductor region provided between the first impurity region and the second impurity region, the semiconductor region having an impurity concentration lower than the peak concentration of the first conductivity type impurity contained in the first impurity region and the peak concentration of the second conductivity type impurity contained in the second impurity region.

[0008] In a photodetector according to an embodiment of the present disclosure, a semiconductor substrate has a plurality of pixels arranged in an array in an in-plane direction, a first impurity region containing a first conductivity type impurity is provided at approximately the center of a pixel on a first surface side of the semiconductor substrate, a second impurity region containing a second conductivity type impurity is embedded in the semiconductor substrate to surround the first impurity region, and a semiconductor region having an impurity concentration lower than the peak concentrations of the impurities contained in the first impurity region and the second impurity region is provided between the first impurity region and the second impurity region, thereby enabling a lower voltage for the multiplication region.

[0009] FIG. 1 is a cross-sectional view schematically illustrating an example of a photodetector according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view schematically illustrating an example of a planar layout of a photodetector corresponding to region X (A) and region Y (B) illustrated in FIG. 1. FIG. 3 is a block diagram illustrating an example of a schematic configuration of the photodetector illustrated in FIG. 1. FIG. 4 is an example of an equivalent circuit diagram of a unit pixel of the photodetector illustrated in FIG. 1. FIG. 5 is a characteristic diagram illustrating an example of a charge distribution corresponding to line A-A' illustrated in FIG. 1. FIG. 6 is a cross-sectional view schematically illustrating another example of a planar layout of a photodetector corresponding to region Y illustrated in FIG. 1. FIG. 7 is a cross-sectional view schematically illustrating another example of a planar layout of a photodetector corresponding to region Y illustrated in FIG. 1. FIG. 8A is a cross-sectional view schematically illustrating an example of a method for manufacturing the photodetector illustrated in FIG. 1. FIG. 8B is a cross-sectional view schematically illustrating a process subsequent to FIG. 8A. FIG. 8C is a cross-sectional view schematically illustrating a process subsequent to FIG. 8B. FIG. 8D is a cross-sectional view schematically illustrating a process subsequent to FIG. 8C. FIG. 9 is a cross-sectional view schematically illustrating an example of a photodetector according to Variation 1 of the present disclosure. FIG. 10 is a schematic diagram illustrating an example of a planar layout of a photodetector corresponding to region X shown in FIG. 9 . FIG. 11 is a schematic cross-sectional view illustrating another example of a photodetector according to Modification 1 of the present disclosure. FIG. 12A is a schematic cross-sectional view illustrating an example of a method for manufacturing the photodetector shown in FIG. 1 . FIG. 12B is a schematic cross-sectional view illustrating a step subsequent to FIG. 12A . FIG. 12C is a schematic cross-sectional view illustrating a step subsequent to FIG. 12B . FIG. 12D is a schematic cross-sectional view illustrating a step subsequent to FIG. 12C . FIG. 12E is a schematic cross-sectional view illustrating a step subsequent to FIG. 12D . FIG. 12F is a schematic cross-sectional view illustrating a step subsequent to FIG. 12E . FIG. 13 is a schematic plan view illustrating an example of a photodetector according to Modification 2 of the present disclosure. FIG. 14 is a schematic view illustrating an example of a planar layout of a photodetector corresponding to region X shown in FIG. 13 . FIG. 15 is a schematic plan view illustrating another example of a photodetector according to Modification 2 of the present disclosure. FIG. 16 is a schematic plan view illustrating another example of a photodetector according to Modification 2 of the present disclosure. Fig. 17 is a schematic cross-sectional view illustrating an example of a photodetector according to Modification 3 of the present disclosure. Fig. 18 is a schematic cross-sectional view illustrating another example of a photodetector according to Modification 3 of the present disclosure. Fig. 19 is a schematic cross-sectional view illustrating an example of a photodetector according to Modification 4 of the present disclosure. Fig. 20 is a schematic cross-sectional view illustrating an example of a photodetector according to Modification 5 of the present disclosure.FIG. 21 is a schematic diagram illustrating an example of a planar layout of a photodetector corresponding to region X shown in FIG. 20 . FIG. 22 is a schematic cross-sectional view illustrating another example of a photodetector according to Modification 5 of the present disclosure. FIG. 23 is a schematic cross-sectional view illustrating an example of a planar layout of a photodetector corresponding to region X shown in FIG. 22 . FIG. 24 is a characteristic diagram illustrating another example of charge distribution corresponding to line A-A′ shown in FIG. 1 . FIG. 25 is a characteristic diagram illustrating another example of charge distribution corresponding to line A-A′ shown in FIG. 1 . FIG. 26A is a schematic cross-sectional view illustrating an example of a method for manufacturing a photodetector having the charge distribution shown in FIG. 24 . FIG. 26B is a schematic cross-sectional view illustrating a step subsequent to FIG. 26A . FIG. 26C is a schematic cross-sectional view illustrating a step subsequent to FIG. 26B . FIG. 26D is a schematic cross-sectional view illustrating a step subsequent to FIG. 26C . FIG. 27 is a schematic cross-sectional view illustrating an example of a photodetector according to Modification 7 of the present disclosure. FIG. 28 is a functional block diagram illustrating an example of an electronic device using the photodetector shown in FIG. 1 etc. Fig. 29A is a schematic diagram showing an example of the overall configuration of a light detection system using the light detection device shown in Fig. 1 etc. Fig. 29B is a diagram showing an example of the circuit configuration of the light detection system shown in Fig. 29A Fig. 30 is a diagram showing an example of a schematic configuration of an endoscopic surgery system Fig. 31 is a block diagram showing an example of the functional configuration of a camera head and a CCU Fig. 32 is a block diagram showing an example of a schematic configuration of a vehicle control system Fig. 33 is an explanatory diagram showing an example of the installation positions of an outside vehicle information detection unit and an imaging unit

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The following description is a specific example of the present disclosure, and the present disclosure is not limited to the following aspects. Furthermore, the present disclosure is not limited to the arrangement, dimensions, dimensional ratios, etc. of the components shown in the drawings. The order of description is as follows: 1. Embodiment (An example of a photodetector in which a semiconductor region having an impurity concentration lower than the peak concentrations of the impurities contained in a first impurity region provided approximately in the center of a pixel and a second impurity region embedded in a semiconductor substrate so as to surround the first impurity region is provided between the first impurity region and the second impurity region) 2. Modifications 2-1. Modification 1 (Another Example of the Configuration of the Photodetector) 2-2. Modification 2 (Another Example of the Configuration of the Photodetector) 2-3. Modification 3 (Another Example of the Configuration of the Photodetector) 2-4. Modification 4 (Another Example of the Configuration of the Photodetector) 2-5. Modification 5 (Another Example of the Configuration of the Photodetector) 2-6. Modification 6 (Another Example of the Configuration of the Photodetector) 2-7. Modification 7 (another example of the configuration of the photodetector) 3. Application example 4. Application example

[0011] 1. Embodiment FIG. 1 schematically illustrates an example of a cross-sectional configuration of a photodetector (photodetector 1) according to an embodiment of the present disclosure. FIG. 2A schematically illustrates a planar configuration corresponding to region X of the photodetector 1 illustrated in FIG. 1. FIG. 2B schematically illustrates a planar configuration corresponding to region Y of the photodetector illustrated in FIG. 1. FIG. 3 is a block diagram illustrating a schematic configuration of the photodetector 1 illustrated in FIG. 1, and FIG. 4 illustrates an example of an equivalent circuit of a unit pixel P of the photodetector 1 illustrated in FIG. 1. The photodetector 1 is applied to, for example, a range image sensor (a range image device 1000 described below, see FIG. 28 ) that measures distances using a time-of-flight (ToF) method, an image sensor, and the like.

[0012] The photodetector 1 has a photoelectric conversion function for light with wavelengths ranging from the visible region of 380 nm or more and less than 780 nm to the infrared region of 780 nm or more and less than 2400 nm, for example. The photodetector 1 has a plurality of unit pixels P arranged in an array on a semiconductor substrate 11 having a pair of opposing surfaces (a front surface (surface 11S1) and a back surface (surface 11S2)). The semiconductor substrate 11 has an n-type impurity region (nS1) containing, for example, n-type impurities, provided approximately in the center of the unit pixel P on the surface 11S1 side. ＋ ) 111 and an n-type impurity region (n ＋ A p-type impurity region (p) 111 is embedded in the semiconductor substrate 11 and surrounds the p-type impurity region (p ＋＋ The semiconductor substrate 11 further includes an n-type impurity region (n ＋ ) 111 and p-type impurity region (p ＋＋ ) 112, an n-type impurity region (n ＋ ) 111 and p-type impurity region (p ＋＋ The semiconductor substrate 110 has a low concentration region 113 having an impurity concentration lower than the peak concentration of each impurity contained in the semiconductor substrate 112.

[0013] Here, the semiconductor substrate 11 corresponds to a specific example of a "semiconductor substrate" according to an embodiment of the present disclosure. The surface 11S1 corresponds to a specific example of a "first surface" according to an embodiment of the present disclosure, and the surface 11S2 corresponds to a specific example of a "second surface" according to an embodiment of the present disclosure. The n-type impurity corresponds to a specific example of a "first conductivity type impurity" according to an embodiment of the present disclosure, and the n-type impurity region (n ＋ ) 111 corresponds to a specific example of a "first impurity region" according to an embodiment of the present disclosure. The p-type impurity corresponds to a specific example of a "second conductivity type impurity" according to an embodiment of the present disclosure, and the p-type impurity region (n ＋ The low-concentration region 112 corresponds to a specific example of a "second impurity region" according to an embodiment of the present disclosure. The low-concentration region 113 corresponds to a specific example of a "semiconductor region" according to an embodiment of the present disclosure.

[0014] In the figures, the symbols "p" and "n" represent p-type impurity regions and n-type impurity regions, respectively. Furthermore, the "+" or "-" at the end of "p" represents the impurity concentration of the p-type impurity region. Similarly, the "+" or "-" at the end of "n" represents the impurity concentration of the n-type impurity region. Here, the more "+"s, the higher the impurity concentration, and the more "-"s, the lower the impurity concentration. However, even if regions have the same number of "+"s or "-"s, this does not mean that the impurity concentrations of the respective regions are strictly the same. This also applies to the following figures.

[0015] [Overall Configuration of Photodetection Device] The photodetection device 1 has, for example, a pixel array section 100A in which a plurality of unit pixels P are arranged in an array in the row and column directions. As shown in Fig. 3, the photodetection device 1 has a bias voltage application section 210 together with the pixel array section 100A. The bias voltage application section 210 applies a bias voltage to each unit pixel P of the pixel array section 100A. Below, a case where electrons are read out as signal charges will be described.

[0016] In the photodetector 1, holes can also become signal charges. For example, of electron-hole pairs generated by photoelectric conversion on the multilayer wiring layer 17 side of the strong electric field region in the avalanche multiplication region 13, the holes are guided along the electric field of the strong electric field region. In this case, the holes are multiplied as signal charges. Conversely, of electron-hole pairs generated by photoelectric conversion on the light incident side S1 of the strong electric field region, the electrons are multiplied as signal charges.

[0017] As shown in FIG. 3, the unit pixel P includes a light receiving element 12, a quenching resistance element 220 formed of, for example, a p-type MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), and an inverter 230 formed of, for example, a complementary MOSFET.

[0018] The light receiving element 12 converts incident light into an electrical signal by photoelectric conversion and outputs the signal. Additionally, the light receiving element 12 converts incident light (photons) into an electrical signal by photoelectric conversion and outputs a pulse in response to the incident photons. The light receiving element 12 is, for example, a SPAD (Single Photon Avalanche Diode) element. The SPAD element has a characteristic that, for example, when a large negative voltage is applied to the cathode, an avalanche multiplication region 13 (depletion layer) is formed, and electrons generated in response to the incidence of one photon undergo avalanche multiplication, resulting in a large current flow. For example, the anode of the light receiving element 12 is connected to the bias voltage application unit 210, and the cathode is connected to the source terminal of the quenching resistance element 220. The anode of the light receiving element 12 is connected to the bias voltage application unit 210, and a device voltage V Ｂ is applied.

[0019] The quenching resistance element 220 is connected in series with the light-receiving element 12, with its source terminal connected to the cathode of the light-receiving element 12 and its drain terminal connected to a power supply (not shown). Ｅ The quenching resistance element 220 detects that the voltage due to the electrons avalanche-multiplied in the light-receiving element 12 is a negative voltage V ＢＤ When the voltage reaches the initial voltage, the photodetector 12 emits the electrons multiplied by the photodetector 12, thereby performing quenching to return the voltage to the initial voltage.

[0020] The inverter 230 has an input terminal connected to the cathode of the light-receiving element 12 and the source terminal of the quenching resistor element 220, and an output terminal connected to a downstream arithmetic processing unit (not shown). The inverter 230 outputs a light-receiving signal based on the carriers (electrons) multiplied by the light-receiving element 12. More specifically, the inverter 230 shapes the voltage generated by the electrons multiplied by the light-receiving element 12. The inverter 230 then outputs a light-receiving signal (APD OUT) that generates a pulse waveform, such as that shown in FIG. 4 , starting from the arrival time of one font to the arithmetic processing unit. For example, the arithmetic processing unit performs arithmetic processing to determine the distance to the subject based on the timing at which a pulse indicating the arrival time of one font is generated in each light-receiving signal, thereby determining the distance for each unit pixel P. Then, based on these distances, a distance image is generated in which distances to the subject detected by multiple unit pixels P are arranged in a plane.

[0021] [Configuration of Unit Pixel of Photodetector] The photodetector 1 is, for example, a so-called backside illuminated photodetector in which a circuit board 20 is stacked on the front side of a sensor substrate 10 and light is received from the back side of the sensor substrate 10.

[0022] The sensor substrate 10 includes a semiconductor substrate 11 made of, for example, a silicon (Si) substrate, and a multilayer wiring layer 17. The semiconductor substrate 11 includes a light-receiving element 12 for each unit pixel P. The semiconductor substrate 11 also includes an isolation portion 15 that electrically isolates adjacent unit pixels P. The isolation portion 15 is provided between a plurality of unit pixels P adjacent in the row and column directions, extending between a surface 11S1 and a surface 11S2 of the semiconductor substrate 11. In other words, the isolation portion 15 is provided in a lattice pattern in a plan view across the entire pixel array section 100A. The multilayer wiring layer 17 includes, for example, wiring (e.g., a wiring layer 172 and vias V1a, V1b, and V2) for applying a cathode voltage and an anode voltage to the light-receiving element 12.

[0023] The semiconductor substrate 11 has opposing surfaces 11S1 and 11S2, and a multilayer wiring layer 17 is provided on the surface 11S1 side, and the surface 11S2 is a light-receiving surface for receiving light. As the semiconductor substrate 11, in addition to a Si substrate, a substrate made of a material having a band gap smaller than that of Si, such as germanium (Ge), selenium (Se), carbon (C), gallium arsenide (GaAs), gallium phosphide (GaP), nickel antimonide (NiSb), indium antimonide (InSb), indium arsenide (InAs), indium phosphide (InP), gallium nitride (GaN), silicon carbide (SiC), or indium gallium arsenide (InGaAs), may be used.

[0024] As described above, the semiconductor substrate 11 has an n-type impurity region (n ＋ ) 111 and an n-type impurity region (n ＋ A p-type impurity region (p) 111 is embedded in the semiconductor substrate 11 and surrounds the p-type impurity region (p ＋＋ ) 112 for each unit pixel P. Specifically, ＋＋ ) 112 is an n-type impurity region (n ＋ ) 111 and extending from the surface 11S1 to the surface 11S2 of the semiconductor substrate 11; ＋ The semiconductor substrate 11 further includes an n-type impurity region (n ＋ ) 111 and p-type impurity region (p ＋＋ ) 112, an n-type impurity region (n ＋ ) 111 and p-type impurity region (p ＋＋ The semiconductor substrate 110 has a low concentration region 113 having an impurity concentration lower than the peak concentration of each impurity contained in the semiconductor substrate 112.

[0025] FIG. 5 shows an example of the charge distribution corresponding to the line AA′ shown in FIG. 1. ＋ ) 111 and p-type impurity region (p ＋＋ ) 112, each with a peak concentration of 1e17 / cm３ More than 1e18 / cm ３ The impurities are doped as follows: n-type impurity region (n ＋ ) 111 and p-type impurity region (p ＋＋ ) 112 are preferably sufficiently separated to reduce the electric field therebetween. ＋ ) 111 and the peak concentration point of the p-type impurity region (p ＋＋ The distance L between the point of the peak concentration of the low-concentration region 112 and the low-concentration region 113 is preferably 1 μm or more. The lower the impurity concentration in the low-concentration region 113, the better, and it is desirable for the low-concentration region 113 to be an undoped region. This allows the voltage of the avalanche multiplication region 13, which will be described later, to be lowered.

[0026] The light receiving element 12 is a SPAD element that outputs a cathode voltage by avalanche multiplication of electrons or holes generated when incident light is photoelectrically converted, and has an n-type impurity region (n ＋ ) 111 and a p-type impurity region (p ＋＋ ) 112 and an n-type impurity region (n ＋ ) 111 and p-type impurity region (p ＋＋ ) 112 and a low-concentration region 113 formed between them. In other words, the light receiving element 12 (light receiving section) is a PIN-type photodiode in which an insulating intrinsic semiconductor (so-called I-type semiconductor) is sandwiched between a P-type semiconductor and an N-type semiconductor. In the light receiving element 12, which is a PIN-type photodiode, an avalanche multiplication region 13 is formed in the low-concentration region 113, as shown in FIG. 1 . The avalanche multiplication region 13 is a high electric field region (depletion layer) formed by a large negative voltage applied to the cathode. In the avalanche multiplication region 13, electrons (e － ) is multiplied.

[0027] The surface 11S1 of the semiconductor substrate 11 further includes an n-type impurity region (n) 111 electrically connected to the n-type impurity region (n) 111. ＋＋ The contact layer 14 and the p-type impurity region (p ＋＋) 112 are electrically connected to a cathode voltage generating circuit 51 and an anode voltage generating circuit 52, respectively.

[0028] The separation portions 15 electrically separate adjacent unit pixels P, and are provided in a grid pattern in the pixel array section 100A in a plan view, for example, to separate each of the unit pixels P. The separation portions 15 extend between the surface 11S1 and the surface 11S2 of the semiconductor substrate 11, and for example, penetrate the semiconductor substrate 11. The separation portions 15 may be provided from the surface 11S1 side of the semiconductor substrate 11, or from the surface 11S2 side of the semiconductor substrate 11.

[0029] The isolation portion 15 is made of, for example, silicon oxide (SiO ｘ The separation portion 15 may be formed using an insulating film such as tungsten (W), aluminum (Al), copper (Cu), cobalt (Co), nickel (Ni), or titanium (Ti). The separation portion 15 may also be formed using a metal material having light-shielding properties, such as tungsten (W), aluminum (Al), copper (Cu), cobalt (Co), nickel (Ni), or titanium (Ti), or a silicon compound thereof. The separation portion 15 may also be formed using polysilicon (Poly-Si). When the separation portion 15 is formed using a material having light-shielding properties, a widened portion 15X may be provided on the surface 11S2 of the semiconductor substrate 11, for example, as shown in FIG. 1, in order to suppress the incidence of obliquely incident light between adjacent unit pixels P.

[0030] For example, a layer having a fixed charge (fixed charge film 16) may be provided on the side surface of the isolation portion 15 and the surface 11S2 of the semiconductor substrate 11. The fixed charge film 16 may be a film having a positive fixed charge or a film having a negative fixed charge.

[0031] The fixed charge film 16 is preferably formed using a semiconductor material or a conductive material having a wider band gap than the semiconductor substrate 11. This makes it possible to suppress the generation of dark current at the interface of the semiconductor substrate 11. The fixed charge film 16 is preferably formed using a material such as hafnium oxide (HfO ｘ ), aluminum oxide (AlO ｘ ), zirconium oxide (ZrO ｘ ), tantalum oxide (TaOｘ ), titanium oxide (TiO ｘ ), lanthanum oxide (LaO ｘ ), praseodymium oxide (PrO ｘ ), cerium oxide (CeO ｘ ), neodymium oxide (NdO ｘ ), promethium oxide (PmO ｘ ), samarium oxide (SmO ｘ ), europium oxide (EuO ｘ ), gadolinium oxide (GdO ｘ ), terbium oxide (TbO ｘ ), dysprosium oxide (DyO ｘ ), holmium oxide (HoO ｘ ), thulium oxide (TmO ｘ ), ytterbium oxide (YbO ｘ ), lutetium oxide (LuO ｘ ), yttrium oxide (YO ｘ ), hafnium nitride (HfN ｘ ), aluminum nitride (AlN ｘ ), hafnium oxynitride (HfO ｘ N ｙ ) and aluminum oxynitride (AlO ｘ N ｙ ) etc.

[0032] In the multilayer wiring layer 17, a wiring layer 172 consisting of one or more wirings is formed in an interlayer insulating layer 171. As described above, the wiring layer 172 is for applying, for example, a cathode voltage and an anode voltage to the light receiving element 12. Some of the wirings in the wiring layer 172 are electrically connected to the contact layer 14 through a via V1a. Some of the wirings in the wiring layer 172 are electrically connected to a p-type impurity region (p ＋＋ ) 112. These n-type impurity regions (n ＋ ) 111. ＋＋The via V1b electrically connected to the vias 112 and 113 can be regarded as a cathode electrode and an anode electrode for the light-receiving element 12, respectively. A plurality of pad electrodes 173 are embedded in the surface of the interlayer insulating layer 171 opposite the semiconductor substrate 11 side (surface 17S1 of the multilayer wiring layer 17). The plurality of pad electrodes 173 are electrically connected to some of the wiring of the wiring layer 172 through vias V2. Note that while FIG. 1 shows an example in which one wiring layer 172 is formed in the multilayer wiring layer 17, the total number of wiring layers in the multilayer wiring layer 17 is not limited, and two or more wiring layers may be formed.

[0033] The vias V1a are provided one for each contact layer 14, as shown in FIG. 2B. The vias V1b are provided, for example, in a p-type impurity region (p ＋＋ 6, a plurality of vias V1a may be provided for the contact layer 14. The vias V1b are formed in the p-type impurity region (p ＋＋ ) 112, a plurality of dot-like regions may be provided on the substrate. Alternatively, as shown in FIG. 7, a p-type impurity region (p ＋＋ 7, by continuously forming the via V1b in a frame shape, for example, leakage of light into adjacent unit pixels P caused by internal light emission generated during avalanche multiplication being reflected by, for example, the wiring layer 172 formed in the multilayer wiring layer 17 can be reduced.

[0034] The interlayer insulating layer 171 is made of, for example, silicon oxide (SiO ｘ ), TEOS, silicon nitride (SiN ｘ ) and silicon oxynitride (SiO ｘ N ｙ ) or a laminated film made of two or more of these.

[0035] The wiring layer 172 is formed using, for example, aluminum (Al), copper (Cu), tungsten (W), or the like.

[0036] The vias V1a, V1b, and V2 are formed using a metal material having light-shielding properties, such as tungsten (W), aluminum (Al), copper (Cu), cobalt (Co), nickel (Ni), or titanium (Ti), or a silicon compound thereof. Alternatively, the vias V1a, V1b, and V2 may be formed using polysilicon (Poly-Si).

[0037] The pad electrode 173 is exposed on the bonding surface with the circuit board 20 (surface 17S1 of the multilayer wiring layer 17), and is used, for example, for connection with the circuit board 20. The pad electrode 173 is formed using, for example, copper (Cu).

[0038] The circuit board 20 includes a semiconductor substrate, such as a silicon substrate, and a multilayer wiring layer. The circuit board 20 includes a bias voltage application unit 210 including a cathode voltage generation circuit 51 and an anode voltage generation circuit 52, a readout circuit that outputs pixel signals based on charges output from the unit pixels P of the pixel array unit 100A, and logic circuits including a vertical drive circuit, a column signal processing circuit, a horizontal drive circuit, and an output circuit. A plurality of pad electrodes 201 are embedded in the bonding surface (surface 20S1) of the circuit board 20 that is bonded to the sensor substrate 10. The pad electrodes 201 are used, for example, for connection to the sensor substrate 10. Like the pad electrodes 173, the pad electrodes 201 are formed of, for example, copper (Cu).

[0039] In the photodetector 1, for example, a CuCu bond is formed between the pad electrode 193 and the pad electrode 227. As a result, the cathode of the light-receiving element 12 is electrically connected to the cathode voltage generation circuit 51 provided on the circuit board 20 side, and the anode of the light-receiving element 12 is electrically connected to the anode voltage generation circuit 52.

[0040] On the light-receiving surface (surface 11S2) side of the semiconductor substrate 11, for example, a protective layer 31 and a microlens 32 are provided for each unit pixel P, for example.

[0041] The protective layer 31 is made of, for example, silicon oxide (SiO ｘ ), TEOS, silicon nitride (SiN ｘ ) and silicon oxynitride (SiO ｘ N ｙ ) or a laminated film made of two or more of these.

[0042] The microlens 32 is for condensing light incident from above onto the light receiving element 12, and is made of, for example, silicon oxide (SiO ｘ ) and the like.

[0043] For example, a color filter may be provided between the protective layer 31 and the microlens 32 .

[0044] [Method for Manufacturing Photodetector] The photodetector 1 of this embodiment can be manufactured, for example, as follows.

[0045] 8A to 8D show the manufacturing method of the photodetector 1 in the order of steps. First, a semiconductor substrate 11 is prepared. Next, as shown in FIG. 8A, a p-type impurity region (p ＋＋ 8B, an n-type impurity region (n ＋ 8C, a multilayer wiring layer 17 is formed on the surface 11S1 side of the semiconductor substrate 11 by a back-end process (BEOL), and then the semiconductor substrate 11 is bonded to the circuit board 20.

[0046] Next, as shown in FIG. 8D , the semiconductor substrate 11 is turned upside down and subjected to a front-end process (FEOL). Specifically, first, the surface 11S2 of the semiconductor substrate 11 is thinned to a predetermined thickness by, for example, chemical mechanical polishing (CMP), and then an opening penetrating the semiconductor substrate 11 is formed from the surface 11S2 side of the semiconductor substrate 11 by, for example, photolithography and etching. Next, a fixed charge film 16 is formed on the side and bottom surfaces of the opening and over the surface 11S2 of the semiconductor substrate 11 by, for example, atomic layer deposition (ALD). Next, the opening is filled with an insulating film by, for example, chemical vapor deposition (CVD), physical vapor deposition (PVD), or evaporation, and then the isolation portion 15 is formed by processing by photolithography and etching. After that, a protective layer 31 and a microlens 32 are formed in this order. This completes the photodetector 1 shown in FIG. 1 .

[0047] [Functions and Effects] The photodetector 1 of this embodiment has an n-type impurity region (n ＋ ) 111 is an n-type impurity region (n ＋ A p-type impurity region (p) 111 is embedded in the semiconductor substrate 11 and surrounds the p-type impurity region (p ＋＋ ) 112 is provided for each unit pixel P. The semiconductor substrate 11 further includes an n-type impurity region (n ＋ ) 111 and p-type impurity region (p ＋＋ ) 112, an n-type impurity region (n ＋ ) 111 and p-type impurity region (p ＋＋ The avalanche multiplication region 13 has a low concentration region 113 having an impurity concentration lower than the peak concentration of each impurity contained in the avalanche multiplication region 13. This is described below.

[0048] As described above, a semiconductor device has been developed that aims to improve photodetection efficiency and reduce jitter without relying on increasing the thickness of the substrate by stacking a layered section including a second semiconductor material different from the first semiconductor material on the light incident side of a substrate including a first semiconductor material, via a transition layer, in multiple pixels each including an avalanche photodiode element that photoelectrically converts incident light. However, in such a semiconductor device in which different semiconductor materials are stacked, there is a problem in that the downcount rate deteriorates due to dark current caused by dislocations because of the transition layer between the photoelectric conversion region and the multiplication region.

[0049] In order to reduce the deterioration of the dark count rate due to the dark current generated at the stacking interface of different semiconductor materials, an element that performs photoelectric conversion and multiplication in a semiconductor material (e.g., Ge) with a narrow band gap and a large absorption coefficient can be considered. In this case, since the carriers obtained by photoelectric conversion are multiplied in the semiconductor material with a narrow band gap, it is expected that the dark count rate will further deteriorate due to the tunnel current caused by the electric field.

[0050] In contrast to this, in this embodiment, as described above, an n-type impurity region (n ＋ ) 111 is an n-type impurity region (n ＋ A p-type impurity region (p) 111 is embedded in the semiconductor substrate 11 and surrounds the p-type impurity region (p ＋＋ ) 112 is provided for each unit pixel P, and an n-type impurity region (n ＋ ) 111 and p-type impurity region (p ＋＋ ) 112, an n-type impurity region (n ＋ ) 111 and p-type impurity region (p ＋＋ A low-concentration region 113 having an impurity concentration lower than the peak concentration of each impurity contained in the unit pixel P is provided. That is, a PIN-type SPAD element is provided as the light-receiving element 12 for each unit pixel P. As a result, the avalanche multiplication region 13 is formed in the low-concentration region 113, which makes it possible to lower the voltage of the avalanche multiplication region 13. This makes it possible to suppress the tunnel current.

[0051] As a result, the photodetector 1 of this embodiment can improve the dark count rate.

[0052] Next, Modifications 1 to 7 and application examples of the present disclosure will be described. In the following, the same components as those in the above embodiment will be given the same reference numerals, and the description thereof will be omitted as appropriate.

[0053] 2. Modifications (2-1. Modification 1) Fig. 9 is a schematic representation of an example of a cross-sectional configuration of a photodetector (photodetector 2) according to Modification 1 of the present disclosure. Fig. 10 is a schematic representation of a planar configuration corresponding to region X of the photodetector 2 shown in Fig. 9. Fig. 11 is a schematic representation of another example of a cross-sectional configuration of a photodetector (photodetector 2A) according to Modification 1 of the present disclosure. As with the above embodiment, the photodetectors 2 and 2A are applicable to, for example, a range image sensor (range image device 1000) or an image sensor that measures distance using the ToF method.

[0054] In the above embodiment, an n-type impurity region (n ＋ ) 111, p-type impurity region (p ＋＋ In the photodetector 2 of this modification, for example, a semiconductor substrate 18 made of a different semiconductor material from the semiconductor substrate 11 is embedded in the semiconductor substrate 11, and an n-type impurity region (n ＋ ) 111, p-type impurity region (p ＋＋ ) 112 and a low-concentration region 113. Except for this point, the photodetector 2 has substantially the same configuration as the photodetector 1 of the above embodiment.

[0055] The semiconductor substrate 18 is a substrate on which the light receiving element 12 (light receiving portion) is formed in the photodetector 2. Examples of the semiconductor substrate 18 include substrates made of silicon (Si), germanium (Ge), selenium (Se), carbon (C), gallium arsenide (GaAs), gallium phosphide (GaP), nickel antimonide (NiSb), indium antimonide (InSb), indium arsenide (InAs), indium phosphide (InP), gallium nitride (GaN), silicon carbide (SiC), and indium gallium arsenide (InGaAs). Specifically, when a Si substrate is used as the semiconductor substrate 11, it is preferable to use, as the semiconductor substrate 18, a Ge substrate, for example, which has a larger absorption coefficient and a smaller band gap than Si.

[0056] In FIG. 9, an n-type impurity region (n ＋ ) 111, p-type impurity region (p ＋＋ ) 112 and the low concentration region 113 are provided, but the present invention is not limited to this. ＋＋ The outer periphery of the p-type impurity region (p) 112 may be in contact with the semiconductor substrate 11 as in the photodetector 2A shown in FIG. ＋＋ ) 112 may be formed at the boundary between the semiconductor substrate 11 and the semiconductor substrate 18. This allows the light-detecting device 2A to have an enlarged low-concentration region 113 that serves as a light-receiving portion, compared to the light-detecting device 2.

[0057] The photodetector 2 can be manufactured, for example, as follows.

[0058] 12A to 12F show the manufacturing method of the photodetector 1 in order of steps. First, as shown in FIG. 12A, a semiconductor substrate 11 is prepared. Next, as shown in FIG. 12B, an opening 11H is formed in the semiconductor substrate 11 by, for example, photolithography and etching. Subsequently, as shown in FIG. 12C, a layer made of a semiconductor material different from that of the semiconductor substrate 11 is grown in the opening 11H by, for example, epitaxial growth, to form a semiconductor substrate 18.

[0059] Next, as shown in FIG. 12D, in the same manner as in the above embodiment, a p-type impurity region (p ＋＋ 12E, an n-type impurity region (n ＋ 12F, a multilayer wiring layer 17 is formed on the surface 11S1 side of the semiconductor substrate 11 by a back-end process (BEOL). After that, as in the above embodiment, a circuit board 20 is attached, and the semiconductor substrate 11 is then turned upside down and a front-end process (FEOL) is performed. This completes the photodetector 2 shown in FIG. 9.

[0060] In this way, in the photodetector 2 of this modified example, the semiconductor substrate 18 made of a semiconductor material different from that of the semiconductor substrate 11 is embedded in the semiconductor substrate 11, and an n-type impurity region (n ＋ ) 111, p-type impurity region (p ＋＋ ) 112 and low concentration region 113 are provided. This makes it possible to drive a PIN type SPAD element on a semiconductor substrate such as Ge, which has a larger absorption coefficient and a smaller band gap than Si, on a Si wafer. Therefore, in addition to the effects of the above embodiment, it is possible to reduce the manufacturing cost and the difficulty of the process compared to manufacturing the photodetector 1 of the above embodiment on a semiconductor substrate which has a larger absorption coefficient and a smaller band gap than Si.

[0061] In the photodetector 2A of this modification, a p-type impurity region (p ＋＋ Since the avalanche multiplication region 13 is formed at the boundary between the semiconductor substrate 11 and the semiconductor substrate 18, the low-concentration region 113 serving as the light-receiving portion can be further enlarged. This allows for improved light detection efficiency compared to the photodetector 2. In addition, the voltage required for the avalanche multiplication region 13 can be further reduced, which allows for a further improvement in the dark count rate.

[0062] (2-2. Modification 2) FIG. 13 is a schematic diagram showing an example of a cross-sectional configuration of a photodetector (photodetector 3) according to Modification 2 of the present disclosure. FIG. 14 is a schematic diagram showing a planar configuration corresponding to region X of the photodetector 3 shown in FIG. 13. FIG. 15 is a schematic diagram showing another example of a cross-sectional configuration of a photodetector (photodetector 3A) according to Modification 2 of the present disclosure. FIG. 16 is a schematic diagram showing another example of a cross-sectional configuration of a photodetector (photodetector 3B) according to Modification 2 of the present disclosure. As in the above embodiment, the photodetectors 3, 3A, and 3B are applied to, for example, a range image sensor (range image device 1000) or an image sensor that measures distance using the ToF method.

[0063] The photodetector 3 of this modification has a p-type impurity region (p ＋＋ A low concentration region 113 surrounded by a p-type impurity region (p ＋＋ An n-type impurity region (n) extends in the in-plane direction from a sidewall portion 112A of the n-type impurity region (n ＋ ) 114 is formed. ＋ ) 114 corresponds to a specific example of a “fourth impurity region” according to an embodiment of the present disclosure. Except for this point, the photodetector 3 has substantially the same configuration as the photodetector 1 according to the above embodiment.

[0064] n-type impurity region (n ＋ ) 114 guides holes generated by photoelectric conversion in the low concentration region 113 to the avalanche multiplication region 13. ＋ ) 114 has, for example, an opening 114H at approximately the center of the unit pixel P and is provided so as to surround the avalanche multiplication region 13.

[0065] n-type impurity region (n ＋ ) 114 may further include a p-type impurity region (p ＋＋ The low-concentration region 113 may extend along a sidewall 112A of the low-concentration region 112 toward the surface 11S1 of the semiconductor substrate 11. This allows holes generated by photoelectric conversion in the low-concentration region 113 to be guided more effectively to the avalanche multiplication region 13.

[0066] In the photodetector devices 3 and 3A, a p-type impurity region (p ＋＋ A low concentration region 113 surrounded by a p-type impurity region (p ＋＋ An n-type impurity region (n) extends in the in-plane direction from a sidewall portion 112A of the n-type impurity region (n ＋ ) 114 is formed, but the present invention is not limited to this. For example, as in the photodetector 3B shown in FIG. ＋ ) 114 instead of the p-type impurity region (p ＋ In this case, electrons generated by photoelectric conversion in the low concentration region 113 are guided to the avalanche multiplication region 13.

[0067] In this way, in the photodetector devices 3 and 3B of this modification, the p-type impurity region (p ＋＋ A low concentration region 113 surrounded by a p-type impurity region (p ＋＋ An n-type impurity region (n) extends in the in-plane direction from a sidewall portion 112A of the n-type impurity region (n ＋ ) 114 or p-type impurity region (p ＋ ) 115 is formed. This allows any carriers generated by photoelectric conversion in the low concentration region 113 to be guided to the avalanche multiplication region 13. Therefore, in addition to the effects of the above embodiment, it is possible to improve the light detection efficiency.

[0068] In the photodetector 3A of this modification, a p-type impurity region (p ＋＋ An n-type impurity region (n) extends in the in-plane direction from a sidewall portion 112A of the n-type impurity region (n ＋ ) 114 is further divided into p-type impurity regions (p ＋＋ The light-detecting layer 114 extends along the sidewall 112A of the low-concentration region 112, for example, to the surface 11S1 of the semiconductor substrate 11. This allows holes generated by photoelectric conversion in the low-concentration region 113 to be guided more effectively to the avalanche multiplication region 13. This further improves the light detection efficiency.

[0069] (2-3. Modification 3) Fig. 17 is a schematic diagram showing an example of a cross-sectional configuration of a photodetector (photodetector 4) according to Modification 3 of the present disclosure. Fig. 18 is a schematic diagram showing another example of a cross-sectional configuration of a photodetector (photodetector 4A) according to Modification 3 of the present disclosure. As in the above embodiment, the photodetectors 4 and 4A are applied to, for example, a range image sensor (range image device 1000) or an image sensor that measures distance using the ToF method.

[0070] The photodetector 4 of this modification has a p-type impurity region (p ＋＋ ) 112, a p-type impurity region (p ＋＋ An n-type impurity region (n) 112 is embedded in the semiconductor substrate 11 and surrounds the n-type impurity region (n) 112. ＋ ) 116 is formed. ＋ ) 116 corresponds to a specific example of a “fifth impurity region” according to an embodiment of the present disclosure. Except for this point, the photodetector 4 has substantially the same configuration as the photodetector 1 according to the above embodiment.

[0071] n-type impurity region (n ＋ ) 116 is a p-type impurity region (p ＋＋ The purpose of the n-type impurity region (n) 112 is to prevent the semiconductor substrate 11 from being electrically floating. ＋ ) 116 is a p-type impurity region (p ＋＋ ) 112, a p-type impurity region (p ＋＋ The n-type impurity region (n) 112 is buried in the semiconductor substrate 11. ＋ ) 116 is connected to a p-type impurity region (p ＋＋ ) 112. That is, the p-type impurity region (p ＋＋ ) 112 and n-type impurity region (n ＋ ) 116 are applied with the same potential.

[0072] Furthermore, in the semiconductor substrate 11, a p-type impurity region (p) 117 may be formed along the side surface of the isolation portion 15 so as to extend between the surface 11S1 and the surface 11S2, as in the photodetector 4A shown in FIG. 18. The p-type impurity region (p) 117 is formed in the surface 11S1 by, for example, forming a p-type impurity region (p ＋＋ ) 112 and n-type impurity region (n ＋ ) 116. That is, the p-type impurity region (p ＋＋ ) 112, n-type impurity region (n ＋ The same potential is applied to the p-type impurity region (p) 116 and the p-type impurity region (p) 117. ＋＋ ) 112, the electrically floating state of the semiconductor substrate 11 outside the semiconductor substrate 11 is further suppressed.

[0073] In this way, in the photodetector 4 of this modified example, the p-type impurity region (p ＋＋ ) 112, a p-type impurity region (p ＋＋ An n-type impurity region (n) 112 is embedded in the semiconductor substrate 11 and surrounds the n-type impurity region (n) 112. ＋ ) 116 is formed. ＋＋ The electrically floating state of the semiconductor substrate 11 outside the light receiving element 12 is suppressed. Therefore, in addition to the effect of the above embodiment, it is possible to suppress afterpulses caused by carriers accumulated outside the light receiving element 12.

[0074] Furthermore, in the photodetector 4A of this modification, a p-type impurity region (p) 117 is formed along the sidewall of the isolation portion 15 so as to extend between the surface 11S1 and the surface 11S2. This suppresses dark current caused by the sidewall of the isolation portion 15, thereby reducing carrier generation. Therefore, compared to the photodetector 4, it is possible to further suppress afterpulses.

[0075] 19 is a schematic diagram illustrating an example of a cross-sectional configuration of a light detection device (light detection device 5) according to Modification 4 of the present disclosure. As in the above embodiment, the light detection device 5 is applied to, for example, a range image sensor (range image device 1000) that measures distance using the ToF method, an image sensor, etc.

[0076] The photodetector 5 of this modified example uses a p-type semiconductor substrate 11A, and an n-type impurity region (n ＋ ) 111 and an n-type impurity region (n ＋ ) 111. ＋＋ ) 112 and an n-type impurity region (n ＋ ) 111 and p-type impurity region (p ＋＋ ) 112 and a low-concentration region 113 having an impurity concentration lower than the peak concentration of each impurity contained in the p-type semiconductor substrate 11A. This p-type semiconductor substrate 11A corresponds to a specific example of a "semiconductor substrate of second conductivity type" according to one embodiment of the present disclosure. Except for this point, the photodetector 5 has substantially the same configuration as the photodetector 1 of the above embodiment.

[0077] In this way, the photodetector 5 of this modified example uses a p-type semiconductor substrate 11A, and an n-type impurity region (n ＋ ) 111, p-type impurity region (p ＋＋ ) 112 and the low concentration region 113 are provided. ＋＋ ) 112 of the semiconductor substrate 11 is suppressed from being electrically floating. Therefore, similarly to the third modification, afterpulses caused by carriers accumulated outside the light-receiving element 12 can be suppressed.

[0078] (2-5. Modification 5) FIG. 20 is a schematic representation of an example of a cross-sectional configuration of a photodetector (photodetector 6) according to Modification 5 of the present disclosure. FIG. 21 is a schematic representation of a planar configuration corresponding to region X of the photodetector 6 shown in FIG. 20. FIG. 22 is a schematic representation of another example of a cross-sectional configuration of a photodetector (photodetector 6A) according to Modification 5 of the present disclosure. FIG. 23 is a schematic representation of a planar configuration corresponding to region X of the photodetector 6A shown in FIG. 22. The photodetectors 6 and 6A are, similar to the above-described embodiments, applicable to, for example, a range image sensor (range image device 1000) or an image sensor that measures distance using the ToF method.

[0079] The photodetector 6 of this modification has a p-type impurity region (p ＋＋ In a plan view, the low concentration region 113 surrounded by the n-type impurity region (n ＋ ) 111 and has a groove 19 extending from the surface 11S1 to the surface 11S2 of the semiconductor substrate 11. Except for this point, the photodetector 6 has substantially the same configuration as the photodetector 1 of the above embodiment.

[0080] The grooves 19 are intended to restrict the lateral movement of carriers generated by photoelectric conversion in the low concentration region 113 and to suppress leakage to regions other than the avalanche multiplication region 13. The grooves 19 may be filled with, for example, an insulating film, or may remain as voids.

[0081] On the surface 11S1 of the semiconductor substrate 11 outside the groove 19, a p-type impurity region (p ＋ ) 118 may be formed. ＋ ) 118 corresponds to a specific example of a "seventh impurity region" according to an embodiment of the present disclosure.

[0082] In this way, in the photodetector 6 of this modified example, the p-type impurity region (p ＋＋ In a plan view, the low concentration region 113 surrounded by the n-type impurity region (n ＋) 111 and extending from the surface 11S1 to the surface 11S2 of the semiconductor substrate 11. This restricts the lateral movement of carriers generated by photoelectric conversion in the low concentration region 113, and suppresses leakage to areas other than the avalanche multiplication region 13. Therefore, in addition to the effects of the above embodiment, it is possible to improve the photodetection efficiency.

[0083] In the photodetector 6A of this modification, a p-type impurity region (p ＋ 22, carriers (electrons in this case) generated outside the groove 19 can be guided to the avalanche multiplication region 13. This makes it possible to further improve the light detection efficiency.

[0084] (2-6. Modification 6) FIGS. 24 and 25 show another example of the charge distribution corresponding to the line AA' shown in FIG. 1 in the photodetector 1 according to Modification 6 of the present disclosure.

[0085] n-type impurity region (n ＋ ) 111 and p-type impurity region (p ＋＋ 24 and 25, one or both of the low concentration regions 112 has an impurity concentration of 1e17 / cm 3 or less from the intrinsic impurity concentration in a range of 100 nm or less from the boundary with the low concentration region 113. ３ More than 1e18 / cm ３ The n-type impurity region (n ＋ ) 111 and p-type impurity region (p ＋＋ ) 112, it is easier to secure a distance from the n-type impurity region (n ＋ ) 111 and p-type impurity region (p ＋＋ ) 112, it is possible to further reduce the dark count rate caused by the tunnel current.

[0086] As shown in FIG. 24, a p-type impurity region (p ＋＋ ) 112 can be manufactured, for example, as follows.

[0087] First, as shown in Fig. 26A, an opening 11H is formed in a prepared semiconductor substrate 11 by, for example, photolithography and etching. Next, as shown in Fig. 26B, a p-type impurity region (p ＋＋ Alternatively, for example, p-type impurities are implanted into the side and bottom surfaces of the opening 11H by ion implantation to form a p-type impurity region (p ＋＋ ) 112 is formed. As a result, a p-type impurity region (p ＋＋ ) 112 is formed.

[0088] Subsequently, as shown in FIG. 26C, for example, a low concentration region 113 is grown by epitaxial growth to fill the opening 11H, and then, as in the above embodiment, an n-type impurity region (n ＋ ) 111 and the contact layer 14 are then formed. After that, a multilayer wiring layer 17 is formed on the surface 11S1 side of the semiconductor substrate 11 by a back-end process (BEOL), and a circuit board 20 is bonded to the multilayer wiring layer 17. After that, the semiconductor substrate 11 is turned upside down and a front-end process (FEOL) is performed. As a result, a p-type impurity region (p ＋＋ The photodetector 1 is completed with the photodetector 112 provided.

[0089] 27 is a schematic diagram illustrating an example of a cross-sectional configuration of a light detection device (light detection device 7) according to Modification 7 of the present disclosure. As in the above embodiment, the light detection device 7 is applied to, for example, a range image sensor (range image device 1000) that measures distance using the ToF method, an image sensor, etc.

[0090] In the above-described embodiments, an n-type impurity region (n ＋ ) 111 is an n-type impurity region (n ＋ A p-type impurity region (p) 111 is embedded in the semiconductor substrate 11 and surrounds the p-type impurity region (p ＋＋ In the example shown, a p-type impurity region (p) 112 is provided at the approximate center of the unit pixel P, but the polarity of each impurity region is not limited to this.＋ ) 711 is a p-type impurity region (p ＋ ) 711 is embedded in the semiconductor substrate 11 and surrounds the n-type impurity region (n ＋＋ ) 712, and further, a p-type impurity region (p ＋＋ ) is provided as a contact layer 74. With this configuration, the same effects as those of the above embodiment can be obtained.

[0091] 28 shows an example of the schematic configuration of a distance image device 1000 as an electronic device equipped with a photodetector (e.g., photodetector 1) according to any of the above-described embodiments and Modifications 1 to 7. This distance image device 1000 corresponds to a specific example of a "distance measuring device" of the present disclosure.

[0092] The range image device 1000 includes, for example, a light source device 1100 , an optical system 1200 , a light detection device 1 , an image processing circuit 1300 , a monitor 1400 , and a memory 1500 .

[0093] The distance image device 1000 can obtain a distance image corresponding to the distance to the illuminated object 1600 by receiving light (modulated light or pulsed light) projected from the light source device 1100 toward the illuminated object 1600 and reflected from the surface of the illuminated object 1600.

[0094] The optical system 1200 is configured with one or more lenses, and guides image light (incident light) from the irradiation object 1600 to the photodetector 1, forming an image on the light receiving surface (sensor section) of the photodetector 1.

[0095] The image processing circuit 1300 performs image processing to construct a distance image based on the distance signal supplied from the light detection device 1, and the distance image (image data) obtained by this image processing is supplied to the monitor 1400 for display, or supplied to the memory 1500 for storage (recording).

[0096] In the range imaging device 1000 configured in this manner, by applying the above-described photodetector (for example, the photodetector 1), it is possible to calculate the distance to the illuminated object 1600 based solely on the light-receiving signals from the highly stable unit pixels P, and generate a highly accurate range image. In other words, the range imaging device 1000 can acquire a more accurate range image.

[0097] (Application Example 2) Fig. 29A schematically illustrates an example of the overall configuration of a light detection system 2000 including the light detection device 1. Fig. 29B illustrates an example of the circuit configuration of the light detection system 2000. The light detection system 2000 includes a light emitting device 2001 serving as a light source unit that emits infrared light L2, and a light detection device 2002 serving as a light receiving unit having a photoelectric conversion element. The light detection device 1 described above can be used as the light detection device 2002. The light detection system 2000 may further include a system control unit 2003, a light source driving unit 2004, a sensor control unit 2005, a light source side optical system 2006, and a camera side optical system 2007.

[0098] The photodetector 2002 can detect light L1 and light L2. Light L1 is external ambient light reflected by the object (measurement target) 2100 ( FIG. 29A ). Light L2 is light emitted by the light-emitting device 2001 and then reflected by the object 2100. Light L1 is, for example, visible light, and light L2 is, for example, infrared light. Light L1 can be detected by a photoelectric conversion unit in the photodetector 2002, and light L2 can be detected by a photoelectric conversion region in the photodetector 2002. Image information of the object 2100 can be obtained from light L1, and distance information between the object 2100 and the photodetector system 2000 can be obtained from light L2. The photodetector system 2000 can be mounted, for example, on an electronic device such as a smartphone or a mobile object such as a car. The light-emitting device 2001 can be configured, for example, by a semiconductor laser, a surface-emitting semiconductor laser, or a vertical-cavity surface-emitting laser (VCSEL). The method of detecting the light L2 emitted from the light-emitting device 2001 by the photodetector 2002 can be, for example, an iTOF method, but is not limited to this. In the iTOF method, the photoelectric conversion unit can measure the distance to the subject 2100, for example, by using the time-of-flight (TOF) of light. The method of detecting the light L2 emitted from the light-emitting device 2001 by the photodetector 2002 can also be, for example, a structured light method or a stereo vision method. For example, in the structured light method, a predetermined pattern of light is projected onto the subject 2100, and the distance between the photodetector system 2000 and the subject 2100 can be measured by analyzing the distortion of the pattern. In addition, in the stereo vision method, for example, two or more cameras are used to acquire two or more images of the subject 2100 viewed from two or more different viewpoints, thereby measuring the distance between the photodetector system 2000 and the subject. The light emitting device 2001 and the light detecting device 2002 can be controlled synchronously by a system control unit 2003 .

[0099] 5. Application Example Application Example to an Endoscopic Surgery System 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 applied to an endoscopic surgery system.

[0100] FIG. 30 is a diagram showing an example of a schematic configuration of an endoscopic surgery system to which the technology according to the present disclosure (the present technology) can be applied.

[0101] 30 shows an operator (doctor) 11131 performing surgery on a patient 11132 on a patient bed 11133 using an endoscopic surgery system 11000. As shown in the figure, the endoscopic surgery system 11000 is composed of an endoscope 11100, other surgical tools 11110 such as an insufflation tube 11111 and an energy treatment tool 11112, a support arm device 11120 that supports the endoscope 11100, and a cart 11200 on which various devices for endoscopic surgery are mounted.

[0102] The endoscope 11100 is composed of a lens barrel 11101, a region of a predetermined length from the tip of which is inserted into a body cavity of a patient 11132, and a camera head 11102 connected to the base end of the lens barrel 11101. In the example shown, the endoscope 11100 is configured as a so-called rigid scope having a rigid lens barrel 11101, but the endoscope 11100 may also be configured as a so-called flexible scope having a flexible lens barrel.

[0103] An opening into which an objective lens is fitted is provided at the tip of the lens barrel 11101. A light source device 11203 is connected to the endoscope 11100, and light generated by the light source device 11203 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 11101, and is irradiated via the objective lens toward an object to be observed inside the body cavity of the patient 11132. The endoscope 11100 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0104] An optical system and an image sensor are provided inside the camera head 11102, and light reflected from the object of observation (observation light) is collected onto the image sensor by the optical system. The observation light is photoelectrically converted by the image sensor to generate an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observed image. The image signal is sent to a camera control unit (CCU) 11201 as RAW data.

[0105] The CCU 11201 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and comprehensively controls the operations of the endoscope 11100 and the display device 11202. Furthermore, the CCU 11201 receives an image signal from the camera head 11102 and performs various types of image processing on the image signal, such as development processing (demosaic processing), to display an image based on the image signal.

[0106] Under the control of the CCU 11201, the display device 11202 displays an image based on an image signal that has been subjected to image processing by the CCU 11201.

[0107] The light source device 11203 is composed of a light source such as an LED (light emitting diode), and supplies irradiation light to the endoscope 11100 when photographing the surgical area, etc.

[0108] The input device 11204 is an input interface for the endoscopic surgery system 11000. A user can input various information and instructions to the endoscopic surgery system 11000 via the input device 11204. For example, the user inputs an instruction to change the imaging conditions (type of irradiation light, magnification, focal length, etc.) of the endoscope 11100.

[0109] The treatment tool control device 11205 controls the driving of the energy treatment tool 11112 for cauterizing tissue, incising, sealing blood vessels, etc. The insufflation device 11206 inflates the body cavity of the patient 11132 through the insufflation tube 11111 in order to ensure a clear field of view for the endoscope 11100 and a working space for the surgeon. The recorder 11207 is a device capable of recording various types of information related to the surgery. The printer 11208 is a device capable of printing various types of information related to the surgery in various formats such as text, images, or graphs.

[0110] The light source device 11203, which supplies illumination light to the endoscope 11100 when photographing the surgical site, can be configured from a white light source, such as an LED, a laser light source, or a combination of these. When the white light source is configured from a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, allowing the light source device 11203 to adjust the white balance of the captured image. In this case, it is also possible to time-share images corresponding to each RGB by irradiating the object of observation with laser light from each RGB laser light source and controlling the drive of the image sensor of the camera head 11102 in synchronization with the irradiation timing. According to this method, color images can be obtained without providing a color filter to the image sensor.

[0111] Furthermore, the light source device 11203 may be controlled to change the intensity of light it outputs at predetermined time intervals. By controlling the driving of the image sensor of the camera head 11102 in synchronization with the timing of the change in light intensity to acquire images in a time-division manner and combining the images, it is possible to generate an image with a high dynamic range that is free from so-called blocked-up shadows and blown-out highlights.

[0112] The light source device 11203 may also be configured to provide light in a predetermined wavelength range compatible with special light observation. Special light observation, for example, utilizes the wavelength dependence of light absorption in body tissues to irradiate light with a narrower band than the light irradiated during normal observation (i.e., white light), thereby capturing high-contrast images of specific tissues, such as blood vessels on the surface of mucous membranes, known as narrow-band imaging. Alternatively, special light observation may involve fluorescence observation, in which images are obtained using fluorescence generated by irradiating excitation light onto the body tissue. Fluorescence observation can involve irradiating excitation light onto the body tissue and observing the fluorescence from the tissue (autofluorescence observation), or by locally injecting a reagent such as indocyanine green (ICG) into the body tissue and irradiating the tissue with excitation light corresponding to the fluorescent wavelength of the reagent to obtain a fluorescent image. The light source device 11203 may be configured to provide narrow-band light and / or excitation light compatible with such special light observation.

[0113] FIG. 31 is a block diagram showing an example of the functional configuration of the camera head 11102 and the CCU 11201 shown in FIG.

[0114] The camera head 11102 has a lens unit 11401, an imaging unit 11402, a drive unit 11403, a communication unit 11404, and a camera head control unit 11405. The CCU 11201 has a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera head 11102 and the CCU 11201 are connected to each other via a transmission cable 11400 so that they can communicate with each other.

[0115] The lens unit 11401 is an optical system provided at the connection portion with the lens barrel 11101. Observation light taken in from the tip of the lens barrel 11101 is guided to the camera head 11102 and enters the lens unit 11401. The lens unit 11401 is composed of a combination of multiple lenses including a zoom lens and a focus lens.

[0116] The imaging unit 11402 may include one imaging element (a so-called single-chip type) or multiple imaging elements (a so-called multi-chip type). When the imaging unit 11402 is configured as a multi-chip type, for example, each imaging element may generate an image signal corresponding to each of RGB, and a color image may be obtained by combining these signals. Alternatively, the imaging unit 11402 may be configured to have a pair of imaging elements for acquiring image signals for the right eye and the left eye corresponding to a 3D (dimensional) display. The 3D display allows the surgeon 11131 to more accurately grasp the depth of the biological tissue at the surgical site. Note that when the imaging unit 11402 is configured as a multi-chip type, multiple lens units 11401 may be provided corresponding to each imaging element.

[0117] Furthermore, the imaging unit 11402 does not necessarily have to be provided in the camera head 11102. For example, the imaging unit 11402 may be provided inside the lens barrel 11101, immediately after the objective lens.

[0118] The driving unit 11403 is configured by an actuator, and moves the zoom lens and focus lens of the lens unit 11401 by a predetermined distance along the optical axis under the control of the camera head control unit 11405. This allows the magnification and focus of the image captured by the imaging unit 11402 to be adjusted appropriately.

[0119] The communication unit 11404 is configured by a communication device for transmitting and receiving various types of information to and from the CCU 11201. The communication unit 11404 transmits the image signal obtained from the imaging unit 11402 to the CCU 11201 via the transmission cable 11400 as RAW data.

[0120] Furthermore, the communication unit 11404 receives a control signal for controlling the driving of the camera head 11102 from the CCU 11201 and supplies the control signal to the camera head control unit 11405. The control signal includes information on the imaging conditions, such as information specifying the frame rate of the captured image, information specifying the exposure value at the time of imaging, and / or information specifying the magnification and focus of the captured image.

[0121] The image capturing conditions such as the frame rate, exposure value, magnification, and focus may be appropriately specified by the user, or may be automatically set by the control unit 11413 of the CCU 11201 based on the acquired image signal. In the latter case, the endoscope 11100 is equipped with a so-called AE (Auto Exposure) function, AF (Auto Focus) function, and AWB (Auto White Balance) function.

[0122] The camera head control unit 11405 controls the driving of the camera head 11102 based on a control signal received from the CCU 11201 via the communication unit 11404 .

[0123] The communication unit 11411 is configured by a communication device for transmitting and receiving various information to and from the camera head 11102. The communication unit 11411 receives an image signal transmitted from the camera head 11102 via the transmission cable 11400.

[0124] Furthermore, the communication unit 11411 transmits to the camera head 11102 a control signal for controlling the driving of the camera head 11102. The image signal and the control signal can be transmitted by electrical communication, optical communication, or the like.

[0125] The image processing unit 11412 performs various image processing operations on the image signal, which is RAW data transmitted from the camera head 11102 .

[0126] The control unit 11413 performs various controls related to the imaging of the surgical site, etc. by the endoscope 11100 and the display of the captured image obtained by imaging the surgical site, etc. For example, the control unit 11413 generates a control signal for controlling the driving of the camera head 11102.

[0127] Furthermore, the control unit 11413 displays the captured image showing the surgical site, etc., on the display device 11202 based on the image signal subjected to image processing by the image processing unit 11412. At this time, the control unit 11413 may recognize various objects in the captured image using various image recognition technologies. For example, the control unit 11413 can recognize surgical tools such as forceps, specific biological parts, bleeding, mist generated when using the energy treatment tool 11112, etc., by detecting the shape and color of the edges of objects included in the captured image. When displaying the captured image on the display device 11202, the control unit 11413 may use the recognition results to superimpose various surgical support information on the image of the surgical site. By superimposing the surgical support information and presenting it to the surgeon 11131, the burden on the surgeon 11131 can be reduced and the surgeon 11131 can proceed with the surgery reliably.

[0128] The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 is an electrical signal cable for electrical signal communication, an optical fiber for optical communication, or a composite cable of these.

[0129] In the illustrated example, communication is performed wired using a transmission cable 11400, but communication between the camera head 11102 and the CCU 11201 may also be performed wirelessly.

[0130] The above describes an example of an endoscopic surgery system to which the technology disclosed herein can be applied. The technology disclosed herein can be applied to the imaging unit 11402 among the components described above. Applying the technology disclosed herein to the imaging unit 11402 improves detection accuracy.

[0131] Although an endoscopic surgery system has been described as an example here, the technology disclosed herein may also be applied to other systems, such as a microsurgery system.

[0132] (Application Example to Mobile Object) The technology according to the present disclosure 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 object, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, a robot, construction machinery, or agricultural machinery (tractor).

[0133] FIG. 32 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.

[0134] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 32, 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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 the passengers of the vehicle or the outside of the vehicle of information. In the example of Fig. 32, 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.

[0144] FIG. 33 is a diagram showing an example of the installation position of the imaging unit 12031.

[0145] In FIG. 33, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0146] 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.

[0147] 33 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.

[0148] 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.

[0149] 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 runs autonomously without relying on driver operation.

[0150] 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.

[0151] 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.

[0152] The foregoing has described an example of a mobile object 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 image capture unit 12031 of the above-described configuration. Specifically, the photodetection devices according to the above-described embodiments and their modifications (e.g., photodetection device 1) can be applied to the image capture unit 12031. By applying the technology according to the present disclosure to the image capture unit 12031, it is possible to obtain high-resolution captured images with little noise, thereby enabling high-precision control using the captured images in the mobile object control system.

[0153] The above describes the embodiments, variations 1 to 6, and application examples and applied examples, but the present disclosure is not limited to the above embodiments and can be modified in various ways. For example, the photodetector of the present disclosure does not need to include all of the components described in the above embodiments and may include other layers. For example, when the photodetector 1 detects visible light, a color filter may be provided between the protective layer 31 and the microlens 32.

[0154] Furthermore, the polarity of the semiconductor regions constituting the photodetector device of the present disclosure may be reversed.

[0155] Furthermore, in the photodetector of the present disclosure, the potentials of the anode and cathode are not limited as long as avalanche multiplication occurs when a reverse bias is applied between them.

[0156] Furthermore, the shape of the unit pixel P is not limited to a rectangular shape. For example, the unit pixel P may be octagonal, and a plurality of unit pixels P constituting the pixel array section 100A may be arranged in a honeycomb pattern.

[0157] The effects described in the above embodiments are merely examples, and other effects may be achieved, or may further include other effects.

[0158] The present disclosure may also be configured as follows. According to the present technology configured as follows, in a semiconductor substrate having a plurality of pixels arranged in an array in an in-plane direction, a first impurity region containing a first conductivity type impurity is provided at approximately the center of a pixel on a first surface side of the semiconductor substrate, and a second impurity region containing a second conductivity type impurity is embedded in the semiconductor substrate to surround the first impurity region. Furthermore, a semiconductor region having an impurity concentration lower than the peak concentrations of the impurities contained in the first impurity region and the second impurity region is provided between the first impurity region and the second impurity region. This reduces the voltage of the multiplication region. This makes it possible to improve the dark count rate. (1) A photodetector comprising: a semiconductor substrate having a first surface and a second surface opposing each other and having a plurality of pixels arranged in an array in an in-plane direction; a first impurity region containing a first conductivity type impurity provided substantially at the center of the pixel on the first surface side of the semiconductor substrate; a second impurity region containing a second conductivity type impurity embedded in the semiconductor substrate so as to surround the first impurity region; and a semiconductor region provided between the first impurity region and the second impurity region and having an impurity concentration lower than the peak concentration of the first conductivity type impurity contained in the first impurity region and the peak concentration of the second conductivity type impurity contained in the second impurity region. (2) The photodetector according to (1), wherein the semiconductor substrate has a light receiving section including the first impurity region and the semiconductor region inside the second impurity region, and a multiplication region that avalanche-multiplies carriers generated in the light receiving section is formed in the semiconductor region. (3) The peak concentrations of the first conductivity type impurity contained in the first impurity region and the second conductivity type impurity contained in the second impurity region are each 1e17 / cm ３ More than 1e18 / cm ３(4) The photodetector according to any one of (1) to (3), wherein a distance between a peak concentration point of the first conductivity type impurity contained in the first impurity region and a peak concentration point of the second conductivity type impurity contained in the second impurity region is 1 μm or more. (5) The photodetector according to any one of (1) to (4), wherein the semiconductor substrate includes any one of silicon, germanium, selenium, carbon, gallium arsenide, gallium phosphide, nickel antimonide, indium antimonide, indium arsenide, indium phosphide, gallium nitride, silicon carbide, and indium gallium arsenide. (6) The photodetector according to any one of (1) to (5), wherein the semiconductor substrate includes a first semiconductor substrate having the first surface and the second surface, and a second semiconductor substrate made of a different material from the first semiconductor substrate and embedded in the first surface of the first semiconductor substrate. (7) The photodetector according to (6), wherein the first impurity region, the second impurity region, and the semiconductor region are formed in the second semiconductor substrate. (8) The photodetector according to (7), wherein the second impurity region is formed at a boundary between the first semiconductor substrate and the second semiconductor substrate. (9) The photodetector according to any one of (1) to (8), further comprising a wiring layer on the first surface side of the semiconductor substrate, the wiring layer including a first electrode for applying a voltage to the first impurity region and a second electrode for applying a voltage to the second impurity region within the wiring layer. (10) The photodetector according to any one of (2) to (9), wherein the second impurity region has a sidewall portion surrounding the first impurity region and the semiconductor region in a planar view and extending from the first surface toward the second surface of the semiconductor substrate, and a bottom portion covering a surface of the semiconductor region opposite to the surface facing the first impurity region, and the semiconductor substrate further has a fourth impurity region extending from the sidewall portion of the second impurity region into the plane of the semiconductor region and surrounding the multiplication region. (11) The photodetector according to (10), wherein the fourth impurity region extends along the sidewall portion of the second impurity region toward the first surface.(12) The photodetector according to any one of (10) to (11), wherein the fourth impurity region contains a first conductivity type impurity or a second conductivity type impurity. (13) The photodetector according to any one of (1) to (12), wherein the semiconductor substrate further includes a fifth impurity region containing the first conductivity type impurity and formed outside the second impurity region and embedded in the semiconductor substrate so as to surround the second impurity region. (14) The photodetector according to (11), further including a wiring layer on the first surface side of the semiconductor substrate, wherein the wiring layer includes a third electrode therein that applies a voltage to the fifth impurity region. (15) The photodetector according to (13) or (14), wherein the semiconductor substrate further includes an isolation portion that extends between the first surface and the second surface and electrically isolates adjacent pixels, and a sixth impurity region containing the second conductivity type impurity and provided along a side surface of the isolation portion. (16) The photodetector according to (15), further comprising a wiring layer on the first surface side of the semiconductor substrate, the wiring layer including a first electrode for applying a voltage to the first impurity region and a second electrode for applying a voltage to the second impurity region, the fifth impurity region, and the sixth impurity region. (17) The photodetector according to any one of (6) to (16), wherein the first semiconductor substrate is a semiconductor substrate of a second conductivity type. (18) The photodetector according to any one of (1) to (17), wherein the semiconductor substrate further includes, in a plan view, a trench in the semiconductor region surrounding the first impurity region, the trench surrounding the first impurity region and extending from the first surface toward the second surface. (19) The photodetector according to (18), wherein the semiconductor substrate further includes a seventh impurity region containing a second conductivity type impurity in the first surface of the semiconductor region surrounding the trench. (20) At least one of the first impurity region and the second impurity region adjacent to the semiconductor region has an impurity concentration ranging from approximately intrinsic to 1e17 / cm within a range of 100 nm or less from a boundary with the semiconductor region. ３ More than 1e18 / cm ３ 20. The photodetector according to any one of (1) to (19), having a concentration distribution that varies as follows:

Claims

1. A photodetector comprising: a semiconductor substrate having opposing first and second surfaces, and having a plurality of pixels arranged in an array in an in-plane direction; a first impurity region containing a first conductivity type impurity provided approximately in the center of the pixel on the first surface side of the semiconductor substrate; a second impurity region containing a second conductivity type impurity formed and embedded in the semiconductor substrate so as to surround the first impurity region; and a semiconductor region provided between the first impurity region and the second impurity region, the impurity concentration of which is lower than the peak concentration of the first conductivity type impurity contained in the first impurity region and the peak concentration of the second conductivity type impurity contained in the second impurity region.

2. The photodetector device of claim 1, wherein the semiconductor substrate has a light receiving portion including the first impurity region and the semiconductor region inside the second impurity region, and a multiplication region that avalanche-multiplies carriers generated in the light receiving portion is formed in the semiconductor region.

3. The peak concentration of the first conductivity type impurity contained in the first impurity region and the peak concentration of the second conductivity type impurity contained in the second impurity region are 1e17 / cm ３ More than 1e18 / cm ３ 2. The optical detection device of claim 1, wherein:

4. The photodetector device of claim 1, wherein the distance between the peak concentration point of the first conductivity type impurity contained in the first impurity region and the peak concentration point of the second conductivity type impurity contained in the second impurity region is 1 μm or more.

5. The photodetector device of claim 1, wherein the semiconductor substrate comprises one of silicon, germanium, selenium, carbon, gallium arsenide, gallium phosphide, nickel antimonide, indium antimonide, indium arsenide, indium phosphide, gallium nitride, silicon carbide, and indium gallium arsenide.

6. The photodetector device of claim 1, wherein the semiconductor substrate includes a first semiconductor substrate having the first surface and the second surface, and a second semiconductor substrate made of a different material from the first semiconductor substrate and embedded in the first surface of the first semiconductor substrate.

7. The photodetector according to claim 6, wherein the first impurity region, the second impurity region, and the semiconductor region are formed in the second semiconductor substrate.

8. The photodetector according to claim 7, wherein said second impurity region is formed at the boundary between said first semiconductor substrate and said second semiconductor substrate.

9. The photodetector device according to claim 1, further comprising a wiring layer on the first surface side of the semiconductor substrate, the wiring layer including a first electrode for applying a voltage to the first impurity region and a second electrode for applying a voltage to the second impurity region within the wiring layer.

10. The photodetector device described in claim 2, wherein the second impurity region has a sidewall portion that surrounds the first impurity region and the semiconductor region in a planar view and extends from the first surface of the semiconductor substrate toward the second surface, and a bottom portion that covers the surface of the semiconductor region opposite to the surface facing the first impurity region, and the semiconductor substrate further has a fourth impurity region that extends from the sidewall portion of the second impurity region into the surface of the semiconductor region and surrounds the multiplication region.

11. The photodetector according to claim 10, wherein the fourth impurity region extends along the sidewall of the second impurity region toward the first surface.

12. The photodetector device according to claim 10, wherein the fourth impurity region contains first conductivity type impurities or second conductivity type impurities.

13. The photodetector device according to claim 1, wherein the semiconductor substrate further includes a fifth impurity region containing the first conductivity type impurity, the fifth impurity region being embedded in the semiconductor substrate outside the second impurity region and surrounding the second impurity region.

14. The photodetector according to claim 13, further comprising a wiring layer on the first surface side of the semiconductor substrate, the wiring layer including a third electrode therein for applying a voltage to the fifth impurity region.

15. The photodetector device according to claim 13, wherein the semiconductor substrate further has an isolation portion extending between the first surface and the second surface and electrically isolating adjacent pixels, and a sixth impurity region containing second conductivity type impurities provided along a side surface of the isolation portion.

16. The photodetector device of claim 15, further comprising a wiring layer on the first surface side of the semiconductor substrate, the wiring layer including a first electrode within the layer for applying a voltage to the first impurity region, and a second electrode within the layer for applying a voltage to the second impurity region, the fifth impurity region, and the sixth impurity region.

17. The photodetector device according to claim 6, wherein the first semiconductor substrate is a semiconductor substrate of a second conductivity type.

18. The photodetector device according to claim 1, wherein the semiconductor substrate further has, in a plan view, a trench in the semiconductor region surrounding the first impurity region, the trench surrounding the first impurity region and extending from the first surface toward the second surface.

19. The photodetector device according to claim 18, wherein the semiconductor substrate further comprises a seventh impurity region containing second conductivity type impurities on the first surface of the semiconductor region surrounding the trench.

20. At least one of the first impurity region and the second impurity region adjacent to the semiconductor region has an impurity concentration ranging from approximately intrinsic to 1e17 / cm within a range of 100 nm or less from the boundary with the semiconductor region. ３ More than 1e18 / cm ３ 2. The optical detection device of claim 1, having a concentration distribution that varies as follows:

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