Light detection device and distance measurement device

Abstract

[Problem] To provide a light detection device and a distance measurement device in which it is possible to realize a multiplication region and a photoelectric conversion unit having suitable characteristics. [Solution] A light detection device according to the present disclosure comprises: a substrate (1) which includes, in a region of a single pixel, a first semiconductor layer (11), a second semiconductor layer (12), and a first multiplication region (R2), and in which the first semiconductor layer (11) has sensitivity with respect to infrared light in a first wavelength range, the second semiconductor layer (12) has sensitivity with respect to infrared light in a second wavelength range different from the first wavelength range, and has an absorption coefficient, with respect to the infrared light in the second wavelength range, greater than that of the first semiconductor, and the first multiplication region (R2) multiplies a carrier from the first semiconductor layer (11); and a first electrode (CA2) which is electrically connected to the first multiplication region (R2).

Description

Light detection and ranging devices

[0001] TECHNICAL FIELD Embodiments of the present disclosure relate to light detection devices and distance measurement devices.

[0002] SPADs (Single Photon Avalanche Diodes) have been attracting attention as diodes for photodetectors. When a voltage higher than the breakdown voltage is applied to a SPAD (Geiger mode) and a single photon is received in the multiplication region (pn junction region), avalanche amplification occurs. As a result, a current flows instantaneously through the SPAD, allowing the light (photon) to be detected. SPADs are used, for example, as the photoelectric conversion unit of each pixel in a distance measuring device.

[0003] International Patent Application Publication No. WO2021 / 261093

[0004] A SPAD may be formed using only one type of semiconductor layer or two or more types of semiconductor layers. For example, a SPAD is generally formed using a silicon (Si) substrate as the only type of semiconductor layer. In this case, when using a SPAD for infrared detection, a problem arises in that the Si substrate has a large absorption coefficient in the near infrared (NIR) wavelength band but a small absorption coefficient in the short wavelength infrared (SWIR) wavelength band.

[0005] On the other hand, a semiconductor layer other than a Si layer may be crystal-grown on a Si substrate, and a SPAD may be formed using the Si substrate and the semiconductor layer. This makes it possible to improve the photon detection efficiency (PDE) of the SPAD. However, in this case, a dislocation layer is formed between the Si substrate and the semiconductor layer, which causes a problem of deterioration in the dark count rate (DCR) of the SPAD.

[0006] Therefore, the present disclosure provides a photodetector and a distance measuring device that can realize a photoelectric conversion section and a multiplication region with suitable characteristics.

[0007] A photodetector according to a first aspect of the present disclosure includes a substrate including a first semiconductor layer, a second semiconductor layer, and a first multiplication region within a pixel area, wherein the first semiconductor layer is sensitive to infrared light in a first wavelength band, the second semiconductor layer is sensitive to infrared light in a second wavelength band different from the first wavelength band, and has a larger absorption coefficient for infrared light in the second wavelength band than the first semiconductor layer, and the first multiplication region multiplies carriers from at least the first semiconductor layer. This allows for a photoelectric conversion unit and a multiplication region with suitable characteristics. For example, the single pixel can be configured to suitably detect both infrared light in the first wavelength band and infrared light in the second wavelength band.

[0008] In this first aspect, the first semiconductor layer may be a Si (silicon) layer, and the second semiconductor layer may be a Ge (germanium) layer, which makes it possible to preferably detect infrared light in the NIR wavelength band by carriers from the first semiconductor layer, and to preferably detect infrared light in the SWIR wavelength band by carriers from the second semiconductor layer.

[0009] In this first aspect, the first wavelength band may be a near infrared (NIR) wavelength band, and the second wavelength band may be a short wavelength infrared (SWIR) wavelength band, thereby making it possible to preferably detect infrared light in both the NIR wavelength band and the SWIR wavelength band.

[0010] In this first aspect, the substrate may further include a second multiplication region within the one pixel region that multiplies carriers from at least the second semiconductor layer, and the photodetector may further include a second electrode electrically connected to the second multiplication region, thereby making it possible to preferably detect infrared light in a first wavelength band using the first multiplication region and infrared light in a second wavelength band using the second multiplication region, for example.

[0011] In addition, in the photodetector according to the first aspect, when carriers from the first semiconductor layer are detected via the first electrode, carriers from the second semiconductor layer may be discharged via the second electrode, and when carriers from the second semiconductor layer are detected via the second electrode, carriers from the first semiconductor layer may be discharged via the first electrode. This makes it possible to discharge other carriers when detecting carriers to be detected, for example.

[0012] In addition, in this first aspect, the first multiplication region may be provided in the first semiconductor layer, and the second multiplication region may be provided in the second semiconductor layer, which makes it easier for carriers generated in the first semiconductor layer to reach the first multiplication region, and makes it easier for carriers generated in the second semiconductor layer to reach the second multiplication region, for example.

[0013] In the first aspect, the first multiplication region and the second multiplication region may be provided in the first semiconductor layer, which makes it possible to equalize a bias voltage when detecting infrared light in the first wavelength band and a bias voltage when detecting infrared light in the second wavelength band, for example.

[0014] In this first aspect, the first multiplication region may multiply carriers from the first semiconductor layer and carriers from the second semiconductor layer, thereby making it possible to equalize a bias voltage when detecting infrared light in the first wavelength band and a bias voltage when detecting infrared light in the second wavelength band, for example.

[0015] In this first aspect, the substrate may further include a diffusion region provided at a position overlapping at least a part of the boundary between the first semiconductor layer and the second semiconductor layer, thereby making it possible to restrict the movement of carriers between the first semiconductor layer and the second semiconductor layer, for example.

[0016] In this first aspect, the diffusion regions may be further provided near the boundary between adjacent pixels and near the top surface of the substrate, thereby making it possible to restrict carrier movement between pixels, for example.

[0017] In this first aspect, the substrate may further include a second multiplication region within the one pixel region that multiplies carriers from at least the second semiconductor layer, and the diffusion region may be provided to separate the first multiplication region and the second multiplication region, thereby making it possible to effectively restrict carrier movement between the first semiconductor layer and the second semiconductor layer, for example.

[0018] In this first aspect, the substrate may further include a second multiplication region within the one-pixel region that multiplies carriers from at least the second semiconductor layer, and the diffusion region may be provided so as not to separate the first multiplication region from the second multiplication region, thereby making it possible, for example, to equalize a bias voltage when detecting infrared light in a first wavelength band and a bias voltage when detecting infrared light in a second wavelength band.

[0019] The photodetector device of the first aspect may further include a metal layer provided in the diffusion region with an insulating film interposed therebetween, thereby making it possible to effectively restrict carrier movement between the first semiconductor layer and the second semiconductor layer, for example.

[0020] In addition, on the first side surface, the lower end of the second semiconductor layer may be provided at a position higher than the lower surface of the substrate, which makes it possible to reduce the ratio of the volume of the second semiconductor layer to the volume of the substrate, for example.

[0021] In addition, in the first side face, the lower end of the second semiconductor layer may be located on the lower surface of the substrate, which makes it possible to increase the ratio of the volume of the second semiconductor layer to the volume of the substrate, for example.

[0022] In the first aspect, the second semiconductor layer may be provided laterally of the first semiconductor layer, which makes it possible to reduce the thickness of the substrate, for example.

[0023] In addition, in the first aspect, the second semiconductor layer may be provided in a vertical direction of the first semiconductor layer, which makes it possible to reduce the area of ​​each pixel in a plan view, for example.

[0024] A distance measuring device according to a second aspect of the present disclosure includes an illuminance sensor that detects illuminance, a light-emitting device that emits light to be irradiated onto a subject, a light-receiving device that receives the light reflected by the subject, and a control mechanism that controls the light-emitting device and the light-receiving device based on the illuminance to measure the distance to the subject, wherein the light-receiving device includes a substrate including a first semiconductor layer, a second semiconductor layer, and a first multiplication region within an area corresponding to one pixel, wherein the first semiconductor layer has sensitivity to infrared light in a first wavelength band, the second semiconductor layer has sensitivity to infrared light in a second wavelength band different from the first wavelength band, and has a larger absorption coefficient for infrared light in the second wavelength band than the first semiconductor layer, and the first multiplication region multiplies carriers from at least the first semiconductor layer, and a first electrode electrically connected to the first multiplication region. This makes it possible to realize a photoelectric conversion unit and a multiplication region having suitable characteristics. For example, it is possible to suitably detect infrared light in both the first wavelength band and the second wavelength band with one pixel, and to improve the distance measurement range of the distance measuring device.

[0025] In addition, in this second aspect, the control mechanism may measure the distance by detecting carriers from the first semiconductor layer when the illuminance is a first value, and measure the distance by detecting carriers from the second semiconductor layer when the illuminance is a second value higher than the first value. This makes it possible to preferably detect infrared light in a first wavelength band at low illuminance and to preferably detect infrared light in a second wavelength band at high illuminance, for example.

[0026] In addition, in this second aspect, the light receiving device may include a plurality of pixels arranged in a two-dimensional array, and at least one of the plurality of pixels may include the first semiconductor layer, the second semiconductor layer, the first multiplication region, and the first electrode. This makes it possible to realize, for example, a two-dimensional pixel array in which one or more pixels have suitable characteristics.

[0027] 1 is a cross-sectional view showing the structure of a photodetector of a first embodiment; FIG. 2 is a plan view schematically showing the structure of a photodetector of a first embodiment; FIG. 3 is a cross-sectional view for explaining the operation of the photodetector of the first embodiment; FIG. 4 is another cross-sectional view for explaining the operation of the photodetector of the first embodiment; FIG. 5 is a plan view schematically showing the structure of a photodetector of a first modified example of the first embodiment; FIG. 6 is a plan view schematically showing the structure of a photodetector of a second modified example of the first embodiment; FIG. 7 is a cross-sectional view showing the structure of a photodetector of a second modified example of the first embodiment; FIG. 8 is a cross-sectional view showing the structure of a photodetector of a second embodiment; FIG. 9 is a cross-sectional view showing the structure of a photodetector of a third embodiment; FIG. 10 is a cross-sectional view showing the structure of a photodetector of a fourth embodiment; FIG. 11 is a cross-sectional view for explaining the operation of the photodetector of the fourth embodiment; FIG. 12 is another cross-sectional view for explaining the operation of the photodetector of the fourth embodiment; FIG. 13 is a cross-sectional view showing the structure of a photodetector of a fifth embodiment; FIG. 14 is a cross-sectional view for explaining the operation of the photodetector of the fifth embodiment; FIG. 15 is another cross-sectional view for explaining the operation of the photodetector of the fifth embodiment; FIG. 16 is a cross-sectional view showing the structure of a photodetector of a sixth embodiment; FIG. 17 is a cross-sectional view showing the structure of a photodetector of a modified example of the sixth embodiment; FIG. 18 is a cross-sectional view showing the structure of a photodetector of a seventh embodiment; FIG. 19 is a cross-sectional view showing the structure of a photodetector of a first modified example of the seventh embodiment; FIG. 19 is a cross-sectional view showing the structure of a photodetector of a second modified example of the seventh embodiment; FIG. 19 is a FIG. 13 is a horizontal cross-sectional view showing the structure of a photodetector of an eighth embodiment. FIG. 14 is a cross-sectional view for explaining the operation of the photodetector of the eighth embodiment. FIG. 15 is another cross-sectional view for explaining the operation of the photodetector of the eighth embodiment. FIG. 16 is a block diagram showing the configuration of a distance measuring device of a ninth embodiment. FIG. 17 is a block diagram showing the configuration of a distance measuring device of a tenth embodiment. FIG. 18 is a block diagram showing the configuration of a vehicle of an eleventh embodiment. FIG. 19 is a plan view showing the sensing area of ​​the vehicle of the eleventh embodiment.

[0028] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0029] First Embodiment FIG. 1 is a cross-sectional view showing the structure of a photodetector according to a first embodiment.

[0030] 1, the photodetector of this embodiment includes a substrate 1, an interlayer insulating film 2, and a lens layer 3. The photodetector of this embodiment also includes a plurality of pixels P, and FIG. 1 shows one of these pixels P.

[0031] 1 shows X, Y, and Z axes that are perpendicular to each other. The X and Y directions correspond to the lateral (horizontal) direction, and the Z direction corresponds to the longitudinal (vertical) direction. The +Z direction corresponds to the upward direction, and the −Z direction corresponds to the downward direction. Note that the −Z direction may or may not strictly coincide with the direction of gravity.

[0032] As shown in Fig. 1, each pixel P in this embodiment includes one portion P1 and two portions P2. In Fig. 1, portion P1 is located between portion P2 on the right side (+X direction) and portion P2 on the left side (-X direction). Hereinafter, portion P1 will also be referred to as "center portion P1," the former portion P2 will also be referred to as "right portion P2," and the latter portion P2 will also be referred to as "left portion P2."

[0033] [Substrate 1] The substrate 1 includes three light-receiving regions 1a in each pixel P. In FIG. 1, these light-receiving regions 1a include a light-receiving region 1a provided in the central portion P1, a light-receiving region 1a provided in the right portion P2, and a light-receiving region 1a provided in the left portion P2. Each light-receiving region 1a functions as a photoelectric conversion unit of the photodetector of this embodiment. Furthermore, in the photodetector of this embodiment, a SPAD is formed in each light-receiving region 1a.

[0034] The substrate 1 further includes one isolation region 1b in each pixel P. In FIG. 1 , three light-receiving regions 1a are separated from one another by the isolation regions 1b. These light-receiving regions 1a are not in contact with one another due to the presence of the isolation regions 1b between the light-receiving regions 1a. In this embodiment, the isolation regions 1b are semiconductor regions containing p-type impurities (p+ diffusion regions). The isolation regions 1b are formed, for example, by injecting p-type impurity ions into the substrate 1 by ion implantation. As a result, the portions of the substrate 1 other than the isolation regions 1b become the light-receiving regions 1a. The isolation regions 1b are an example of the diffusion regions of the present disclosure.

[0035] 1, the lower surface of the substrate 1 is the front surface of the substrate 1, and the upper surface of the substrate 1 is the back surface of the substrate 1. In the photodetector of this embodiment, the back surface of the substrate 1 is the light incident surface. In FIG. 1, the front and back surfaces of the substrate 1 are parallel to the X and Y directions and perpendicular to the Z direction.

[0036] The substrate 1 further includes a semiconductor layer 11 and a semiconductor layer 12 within a region corresponding to one pixel. In each pixel P, the region enclosed by the dashed line within the substrate 1 is formed of the semiconductor layer 12, and the other regions within the substrate 1 are formed of the semiconductor layer 11. Thus, the substrate 1 within the central portion P1 includes both the semiconductor layer 11 and the semiconductor layer 12, while the substrate 1 within the right portion P2 and the left portion P2 includes only the semiconductor layer 11. The semiconductor layer 11 is an example of a first semiconductor layer of the present disclosure. The semiconductor layer 12 is an example of a second semiconductor layer of the present disclosure.

[0037] In the substrate 1 of this embodiment, the semiconductor layer 11 is formed of a material (NIR light absorbing material) having high sensitivity to infrared light in the NIR wavelength band, and the semiconductor layer 12 is formed of a material (SWIR light absorbing material) having high sensitivity to infrared light in the SWIR wavelength band. Specifically, the absorption coefficient for infrared light in the SWIR wavelength band is larger in the semiconductor layer 12 than in the semiconductor layer 11. At least one of the semiconductor layers 11 and 12 may also have high sensitivity to visible light. The NIR wavelength band is an example of a first wavelength band in the present disclosure. The SWIR wavelength band is an example of a second wavelength band in the present disclosure.

[0038] For example, the semiconductor layer 11 and the semiconductor layer 12 are a Si (silicon) layer and a semiconductor layer other than a Si layer, respectively. An example of a semiconductor layer other than a Si layer is a Ge (germanium) layer. The substrate 1 is formed, for example, by forming a pattern of a Ge layer (semiconductor layer 12) on a Si substrate (part of the semiconductor layer 11) and then forming a Si layer (the remainder of the semiconductor layer 11) on this pattern.

[0039] In each pixel P of this embodiment, the upper end (upper surface) of the semiconductor layer 12 is located lower than the upper surface of the substrate 1, and the lower end (lower surface) of the semiconductor layer 12 is located higher than the lower surface of the substrate 1. Therefore, the semiconductor layer 12 is sandwiched between an upper portion of the semiconductor layer 12 in the semiconductor layer 11 and a lower portion of the semiconductor layer 12 in the semiconductor layer 11, and is located vertically between these portions. Furthermore, in each pixel P of this embodiment, the semiconductor layer 12 is sandwiched between a right portion of the semiconductor layer 12 in the semiconductor layer 11 and a left portion of the semiconductor layer 12 in the semiconductor layer 11, and is located horizontally between these portions. Therefore, in the XZ cross section shown in FIG. 1 , the semiconductor layer 12 is surrounded by the semiconductor layer 11 in an annular shape.

[0040] Each light-receiving region 1a in this embodiment includes a p+ region 13 containing p-type impurities, an n+ region 14 containing n-type impurities, and an n+ region 15 containing n-type impurities. The lower end of the n+ region 15 is located on the lower surface of the substrate 1. The n+ region 14 is provided on the n+ region 15. The p+ region 13 is provided on the n+ region 14, and the right and left ends of the p+ region 13 contact the isolation region 1b. Each light-receiving region 1a in this embodiment further includes a pn junction region 16 between the p+ region 13 and the n+ region 14.

[0041] In the central portion P1, the p+ region 13, the n+ region 14, and the pn junction region 16 are provided in the semiconductor layer 12, and the n+ region 15 is provided in the semiconductor layer 11. In this embodiment, the pn junction region 16 in the central portion P1 functions as a multiplication region R1 that multiplies carriers from the semiconductor layer 12 in the central portion P1. The multiplication region R1 in the central portion P1 is an example of the second multiplication region of the present disclosure. In the central portion P1, the portion (semiconductor layer 12) above the p+ region 13 in the light-receiving region 1a mainly serves as the region that receives light.

[0042] In the right portion P2, p+ region 13, n+ region 14, n+ region 15, and pn junction region 16 are provided in semiconductor layer 11. In this embodiment, pn junction region 16 in right portion P2 functions as multiplication region R2 that multiplies carriers from semiconductor layer 11 in right portion P2. Multiplication region R2 in right portion P2 is an example of the first multiplication region of the present disclosure. In right portion P2, the portion (semiconductor layer 11) above p+ region 13 in light receiving region 1a mainly serves as the region that receives light.

[0043] In the left portion P2, p+ region 13, n+ region 14, n+ region 15, and pn junction region 16 are provided in semiconductor layer 11. In this embodiment, pn junction region 16 in left portion P2 functions as multiplication region R2 that multiplies carriers from semiconductor layer 11 in left portion P2. Multiplication region R2 in left portion P2 is also an example of the first multiplication region of the present disclosure. In left portion P2, the portion (semiconductor layer 11) above p+ region 13 in light-receiving region 1a mainly serves as the region that receives light.

[0044] In the substrate 1 of this embodiment, the separation region 1b separates the multiplication region R1 in the central portion P1, the multiplication region R2 in the right portion P2, and the multiplication region R2 in the left portion P2 from each other. Therefore, all paths between the multiplication region R1 and each multiplication region R2 in the substrate 1 pass through the separation region 1b. The same applies to paths between one multiplication region R2 and the other multiplication region R2 in the substrate 1. This makes it possible to restrict carriers generated in one light-receiving region 1a from moving to the multiplication region R1 or R2 provided in another light-receiving region 1a.

[0045] In the pixel P shown in FIG. 1 , the isolation region 1b includes a plurality of lateral isolation regions 17 provided on the sides of the light-receiving region 1a and one upper isolation region 18 provided above the light-receiving region 1a. The upper isolation region 18 is provided near the top surface of the substrate 1. Meanwhile, FIG. 1 shows, as the plurality of lateral isolation regions 17, a lateral isolation region 17 provided between the light-receiving region 1a in the central portion P1 and the light-receiving region 1a in the right portion P2, and a lateral isolation region 17 provided between the light-receiving region 1a in the central portion P1 and the light-receiving region 1a in the left portion P2. FIG. 1 further shows a lateral isolation region 17 provided near the boundary between the right portion P2 of the pixel P shown in FIG. 1 and another pixel P, and a lateral isolation region 17 provided near the boundary between the left portion P2 of the pixel P shown in FIG. 1 and another pixel P. 1 includes a lateral isolation region 17 (not shown) provided in the +Y direction of each light-receiving region 1a and a lateral isolation region 17 (not shown) provided in the −Y direction of each light-receiving region 1a as the plurality of lateral isolation regions 17. As a result, the plurality of lateral isolation regions 17 form a net-like (mesh-like) shape as a whole in a plan view.

[0046] The dashed line in FIG. 1 indicates the boundary (interface) between the semiconductor layer 11 and the semiconductor layer 12. In FIG. 1, the boundary between the semiconductor layer 11 and the semiconductor layer 12 includes a portion corresponding to the upper surface of the semiconductor layer 12, a portion corresponding to the lower surface of the semiconductor layer 12, a portion corresponding to the right side surface of the semiconductor layer 12, and a portion corresponding to the left side surface of the semiconductor layer 12. The isolation region 1b in this embodiment is provided at a position overlapping a portion of the boundary between the semiconductor layer 11 and the semiconductor layer 12. Specifically, the upper isolation region 18 overlaps the upper surface of the semiconductor layer 12, the lateral isolation region 17 between the central portion P1 and the right portion P2 overlaps the right side surface of the semiconductor layer 12, and the lateral isolation region 17 between the central portion P1 and the left portion P2 overlaps the left side surface of the semiconductor layer 12. These lateral isolation regions 17 also overlap a portion of the lower surface of the semiconductor layer 12. Furthermore, the above-mentioned lateral isolation region 17 (not shown) may also overlap with the side surfaces (not shown) of the semiconductor layer 12 in the ±Y directions.

[0047] According to this embodiment, by providing the separation region 1b at a position overlapping the boundary between the semiconductor layer 11 and the semiconductor layer 12, it is possible to provide a potential barrier by the separation region 1b between the semiconductor layer 11 and the semiconductor layer 12. This makes it possible to distance each light-receiving region 1a from the boundary between the semiconductor layer 11 and the semiconductor layer 12 and to restrict the movement of carriers between the light-receiving regions 1a by the potential barrier.

[0048] [Interlayer insulating film 2] The interlayer insulating film 2 is provided on the lower surface of the substrate 1. The photodetector of this embodiment further includes a plurality of contact plugs 21 and a plurality of contact plugs 22 provided in the interlayer insulating film 2 below the substrate 1.

[0049] In FIG. 1 , the plurality of contact plugs 21 include a cathode electrode CA1 for a SPAD in the central portion P1, a cathode electrode CA2 for a SPAD in the right portion P2, and a cathode electrode CA2 for a SPAD in the left portion P2. The cathode electrode CA1 is provided below the n+ region 15 in the central portion P1 and is electrically connected to the multiplication region R1 in the central portion P1. The former cathode electrode CA2 is provided below the n+ region 15 in the right portion P2 and is electrically connected to the multiplication region R2 in the right portion P2. The latter cathode electrode CA2 is provided below the n+ region 15 in the left portion P2 and is electrically connected to the multiplication region R2 in the left portion P2. The cathode electrode CA1 is an example of a second electrode of the present disclosure. Each cathode electrode CA2 is an example of a first electrode of the present disclosure.

[0050] 1, the plurality of contact plugs 22 include four cathode electrodes AN for the SPADs in the central portion P1, the right portion P2, and the left portion P2. These anode electrodes AN are provided under four lateral isolation regions 17, respectively, and are electrically connected to the multiplication region R1 in the central portion P1, the multiplication region R2 in the right portion P2, and the multiplication region R2 in the left portion P2 via these lateral isolation regions 17.

[0051] In the photodetector of this embodiment, when detecting SWIR light using pixel P shown in FIG. 1 , a constant voltage is applied to cathode electrode CA1 and a ground voltage is applied to each cathode electrode CA2. This causes an avalanche in multiplication region R1, allowing carriers to be detected via multiplication region R1 while the carriers are discharged via multiplication region R2. Similarly, in the photodetector of this embodiment, when detecting NIR light using pixel P shown in FIG. 1 , a constant voltage is applied to each cathode electrode CA2 and a ground voltage is applied to cathode electrode CA1. This causes an avalanche in multiplication region R2, allowing carriers to be detected via multiplication region R2 while the carriers are discharged via multiplication region R1. Further details of these processes will be described later.

[0052] [Lens Layer 3] The lens layer 3 is provided on the upper surface of the substrate 1. The lens layer 3 of this embodiment includes three lenses 31 in each pixel P. In FIG. 1 , the lens layer 3 includes a lens 31 provided on the substrate 1 in the central portion P1, a lens 31 provided on the substrate 1 in the right portion P2, and a lens 31 provided on the substrate 1 in the left portion P2. The photoelectric conversion units in the central portion P1, the right portion P2, and the left portion P2 convert light incident through the lenses 31 in the central portion P1, the right portion P2, and the left portion P2 into electric charges, respectively.

[0053] 2 is a plan view schematically showing the structure of the photodetector of the first embodiment. As shown in FIG. 2, the photodetector of this embodiment includes a pixel array 41 and a control unit 42.

[0054] The pixel array 41 includes a plurality of pixels P arranged in a two-dimensional array in a planar view. The pixel P shown in FIG. 1 is one of the plurality of pixels P shown in FIG. 2. As described above, each pixel P in this embodiment includes one portion P1 (center portion P1) and two portions P2 (right portion P2 and left portion P2). In FIG. 2, the boundaries between pixels P are indicated by thick lines, and the boundaries between portions P1 and P2 within each pixel P are indicated by thin lines. Each portion P1 includes semiconductor layers 11 and 12 ( FIG. 1 ), and each portion P2 includes only the semiconductor layer 11 of the semiconductor layers 11 and 12. Note that the number of portions P1 within each pixel P may be other than one, and the number of portions P2 within each pixel P may be other than two.

[0055] The control unit 42 controls the operation of the photodetector device of this embodiment, for example, the operation of the pixel array 41. The control unit 42 of this embodiment is formed by a circuit (not shown) provided in the interlayer insulating film 2 ( FIG. 1 ). The control unit 42 controls, for example, the operations shown in FIGS. 3 and 4 , which will be described later.

[0056] FIG. 3 is a cross-sectional view for explaining the operation of the photodetector of the first embodiment.

[0057] 3 shows the state of the photodetector during SWIR sensing. For example, the photodetector of this embodiment is provided in a distance measuring device, and during SWIR sensing, each pixel P detects SWIR light for distance measurement performed by the distance measuring device. In this embodiment, long-distance distance measurement is performed by performing SWIR sensing under high illuminance. Distance measurement under high illuminance is performed, for example, under conditions with strong background light, such as outdoors.

[0058] The operation of the photodetector during SWIR sensing will be described below using pixel P shown in FIG. 3 as an example.

[0059] During SWIR sensing, the photodetector of this embodiment applies a sufficient bias voltage Vex1 (≠0 V) to the cathode electrode CA1 of this pixel P, and applies a ground voltage GND (=0 V) to each cathode electrode CA2 of this pixel P. The photodetector of this embodiment further applies a voltage Vbd to each anode electrode AN of this pixel P.

[0060] As a result, carriers generated in the light-receiving region 1a (semiconductor layer 12) of portion P1 cause a SPAD reaction in the multiplication region R1 of portion P1, as shown in FIG. 3. The carriers generated in the light-receiving region 1a of portion P1 include photoelectrons indicated by white circles and dark current indicated by black circles. The photodetector of this embodiment detects the SWIR light incident on the pixel P by detecting the carriers via the multiplication region R1 (cathode electrode CA1).

[0061] FIG. 3 further shows carriers generated in the light-receiving region 1a (semiconductor layer 11) of each portion P2. The carriers generated in the light-receiving region 1a of each portion P2 include dark currents indicated by black circles. The photodetector of this embodiment detects carriers from the light-receiving region 1a of each portion P1 via the multiplication region R1, while discharging carriers from the light-receiving region 1a of each portion P2 via the respective multiplication regions R2 (respective cathode electrodes CA2). Note that the dark current of each portion P2 is discharged from the respective multiplication regions R2, and the dark current of portion P1 is discharged from the respective multiplication region R1.

[0062] FIG. 4 is another cross-sectional view for explaining the operation of the photodetector of the first embodiment.

[0063] 4 shows the state of the photodetector during NIR sensing. For example, the photodetector of this embodiment is provided in the above-mentioned distance measuring device, and during NIR sensing, each pixel P detects NIR light for distance measurement performed by the distance measuring device. In this embodiment, short-distance distance measurement is performed by performing NIR sensing under low illuminance. Distance measurement under low illuminance is performed, for example, under conditions where background light is weak, such as indoors.

[0064] The operation of the photodetector during NIR sensing will be described below using pixel P shown in FIG. 4 as an example.

[0065] During NIR sensing, the photodetector of this embodiment applies a sufficient bias voltage Vex2 (≠0 V) to each cathode electrode CA2 of this pixel P, and applies a ground voltage GND (=0 V) to the cathode electrode CA1 of this pixel P. In this embodiment, the bias voltage Vex2 has a value different from the bias voltage Vex1, but may instead have the same value as the bias voltage Vex1. The photodetector of this embodiment further applies a voltage Vbd to each anode electrode AN of this pixel P.

[0066] As a result, carriers generated in the light-receiving region 1a (semiconductor layer 11) of each portion P2 cause a SPAD reaction in the multiplication region R1 of each portion P2, as shown in FIG. 4 . The carriers generated in the light-receiving region 1a of each portion P2 include photoelectrons indicated by white circles and dark current indicated by black circles. The photodetector of this embodiment detects the NIR light incident on the pixel P by detecting the carriers via each multiplication region R2 (each cathode electrode CA2).

[0067] 4 further shows carriers generated in the light-receiving region 1a (semiconductor layer 12) of portion P1. The carriers generated in the light-receiving region 1a of portion P1 also include photoelectrons indicated by white circles and dark current indicated by black circles. The photodetector of this embodiment detects carriers from the light-receiving region 1a of each portion P2 via each multiplication region R2, while discharging carriers from the light-receiving region 1a of portion P1 via multiplication region R1 (cathode electrode CA1).

[0068] The advantages of the photodetector of this embodiment will be described below with reference to FIGS.

[0069] The photodetector of this embodiment includes, within each pixel P, a semiconductor layer 11 (e.g., a Si layer) that has high sensitivity to infrared light in the NIR wavelength band and a semiconductor layer 12 (e.g., a Ge layer) that has high sensitivity to infrared light in the SWIR wavelength band. This makes it possible to form a photoelectric conversion unit and multiplication regions R1 and R2 with suitable characteristics within each pixel P. For example, by detecting SWIR light using the semiconductor layer 12 and multiplication region R1 and detecting NIR light using the semiconductor layer 11 and multiplication region R2, it becomes possible to suitably detect both SWIR light and NIR light in each pixel P. Furthermore, by using the semiconductor layer 11 and the semiconductor layer 12, it becomes possible to improve the ranging range of the distance measuring device.

[0070] When the semiconductor layer 12 is a Ge layer, the semiconductor layer 12 is also sensitive to infrared light in the NIR wavelength band. Therefore, in FIG. 4 , photoelectrons indicated by open circles are generated not only in portion P2 but also in portion P1. Therefore, NIR light can also be detected using the semiconductor layer 12 and the multiplication region R1. However, Ge layers have poorer DCR characteristics than Si layers. Therefore, when the semiconductor layer 11 is a Si layer and the semiconductor layer 12 is a Ge layer, it is desirable to detect NIR light using the semiconductor layer 11 and the multiplication region R2, as in this embodiment. During NIR sensing as shown in FIG. 4 , dark current generated in the semiconductor layer 12 (Ge layer), which has many defects, can be easily discharged via the multiplication region R1 and the cathode electrode CA1. This makes it possible to suppress deterioration of the DCR. According to this embodiment, it is possible to enjoy both the advantages of the Ge layer, which has high sensitivity to infrared light in the SWIR wavelength band, and the Si layer, which has good DCR characteristics.

[0071] The semiconductor layer 11 may be a semiconductor layer other than a Si layer as long as it has sensitivity to infrared light in the NIR wavelength band. Similarly, the semiconductor layer 12 may be a semiconductor layer other than a Ge layer as long as it has sensitivity to infrared light in the SWIR wavelength band. In this embodiment, the absorption coefficient for infrared light in the SWIR wavelength band is higher in the semiconductor layer 12 than in the semiconductor layer 11. For example, the absorption coefficient for infrared light in the SWIR wavelength band of the Ge layer is higher than the absorption coefficient for infrared light in the SWIR wavelength band of the Si layer. On the other hand, the absorption coefficient for infrared light in the NIR wavelength band of the semiconductor layer 11 may be higher than in the semiconductor layer 12, or may be higher than in the semiconductor layer 11.

[0072] The semiconductor layer 11 may have high sensitivity only to infrared light in a predetermined wavelength band included in the NIR wavelength band, among infrared light in the NIR wavelength band. In this case, the distance measurement of this embodiment using NIR light may be performed using NIR light in the predetermined wavelength band. The semiconductor layer 12 may have high sensitivity only to infrared light in a predetermined wavelength band included in the SWIR wavelength band, among infrared light in the SWIR wavelength band. In this case, the distance measurement of this embodiment using SWIR light may be performed using SWIR light in the predetermined wavelength band. The above-mentioned relationship that "the absorption coefficient for infrared light in the SWIR wavelength band is larger in the semiconductor layer 12 than in the semiconductor layer 11" may hold only for a part of the SWIR wavelength band including the predetermined wavelength band.

[0073] FIG. 5 is a plan view schematically showing the structure of a photodetector according to a first modified example of the first embodiment.

[0074] The photodetector of this modified example includes a pixel array 41 and a control unit 42, similar to the photodetector of the first embodiment shown in Fig. 2. However, while each pixel P of the first embodiment includes one portion P1 and two portions P2, each pixel P of this modified example includes one portion P1 and one portion P2. When the area of ​​each portion P1 and the area of ​​each portion P2 in a plan view are the same between the first embodiment and this modified example, according to this modified example, the number of portions P2 in each pixel P can be reduced to one, thereby reducing the area of ​​each pixel P in a plan view.

[0075] FIG. 6 is a plan view schematically showing the structure of a photodetector according to a second modified example of the first embodiment.

[0076] The photodetector of this modified example includes a pixel array 41 and a control unit 42, similar to the photodetector of the first embodiment shown in Fig. 2. However, while each pixel P of the first embodiment includes one portion P1 and two portions P2, each pixel P of this modified example includes one portion P1 and eight portions P2. If the area of ​​each portion P1 and the area of ​​each portion P2 in a plan view are the same between the first embodiment and this modified example, according to this modified example, by increasing the number of portions P2 in each pixel P to eight, it is possible to increase the proportion of the area of ​​the portions P2 in the area of ​​each pixel P.

[0077] As described above, the photodetector of this embodiment includes, in each pixel P, a semiconductor layer 11 (e.g., a Si layer) having high sensitivity to infrared light in the NIR wavelength band and a semiconductor layer 12 (e.g., a Ge layer) having high sensitivity to infrared light in the SWIR wavelength band. Furthermore, the absorption coefficient for infrared light in the SWIR wavelength band is larger in the semiconductor layer 12 than in the semiconductor layer 11. Therefore, according to this embodiment, it is possible to form a photoelectric conversion unit and multiplication regions R1 and R2 having suitable characteristics in each pixel P. For example, it is possible to suitably detect both SWIR light and NIR light in each pixel P and to improve the DCR in each pixel P.

[0078] Second Embodiment FIG. 7 is a cross-sectional view showing the structure of a photodetector according to a second embodiment.

[0079] The photodetector of this embodiment includes, in addition to the components of the photodetector of the first embodiment ( FIG. 1 ), an insulating film 51 and a light-shielding layer 52 provided in each upper isolation region 18. The light-shielding layer 52 is, for example, a metal layer having a light-shielding effect. The light-shielding layer 52 is embedded in a trench formed to penetrate the substrate 1 in the Z direction, with the insulating film 51 interposed therebetween. The light-shielding layer 52 further extends in the Z direction within the interlayer insulating film 2.

[0080] The light-shielding layer 52 of this embodiment is provided to separate the light-receiving region 1 a in the center portion P1 from the light-receiving regions 1 a in the right portion P2 and the left portion P2. This effectively restricts carrier movement between these portions P1 and P2, thereby suppressing deterioration of the DCR. For example, it is possible to effectively suppress carrier inflow from each multiplication region R2 to the multiplication region R1 while a SPAD reaction is occurring in the multiplication region R1, and to effectively suppress carrier inflow from the multiplication region R1 to each multiplication region R2 while a SPAD reaction is occurring in each multiplication region R2.

[0081] 7, the light-shielding layer 52 is provided not only between the central portion P1 and the right portion P2 and between the central portion P1 and the left portion P2 (first region), but also between the right portion P2 of the pixel P shown in FIG. 1 and another pixel P and between the left portion P2 of the pixel P shown in FIG. 1 and another pixel P (second region). However, the light-shielding layer 52 may be provided in the first region but not in the second region. Furthermore, if the light-shielding effect of the light-shielding layer 52 is not necessary, the photodetector of this embodiment may include a metal layer that does not have a light-shielding effect instead of the light-shielding layer 52.

[0082] Third Embodiment FIG. 8 is a cross-sectional view showing the structure of a photodetector according to a third embodiment.

[0083] The photodetector of this embodiment has the same components as the photodetector of the first embodiment ( FIG. 1 ). However, the lower surface of the semiconductor layer 12 of this embodiment is located at the same height as the upper surface of the p+ region 13, not at the same height as the lower surface of the n+ region 14 (the upper surface of the n+ region 15). Therefore, the multiplication regions R1 and R2 of this embodiment are both located within the semiconductor layer 11.

[0084] According to this embodiment, by providing both multiplication regions R1 and R2 within the semiconductor layer 11, it is possible to equalize the value of the bias voltage Vex1 during SWIR sensing and the value of the bias voltage Vex2 during NIR sensing, which makes it possible to simplify, for example, the circuit configuration of the photodetector of this embodiment.

[0085] Fourth Embodiment FIG. 9 is a cross-sectional view showing the structure of a photodetector according to a fourth embodiment.

[0086] The photodetector of this embodiment has the same components as the photodetector of the first embodiment ( FIG. 1 ). However, while the three light-receiving regions 1 a in each pixel P of the first embodiment are separated from one another by an isolation region 1 b, the three light-receiving regions 1 a in each pixel P of this embodiment are not separated from one another by an isolation region 1 b. In FIG. 9 , the lateral isolation region 17 between the central portion P1 and the right portion P2 and the lateral isolation region 17 between the central portion P1 and the left portion P2 do not extend to the bottom surface of the substrate 1. As a result, while the three light-receiving regions 1 a in each pixel P of the first embodiment are not in contact with one another, the three light-receiving regions 1 a in each pixel P of this embodiment are in contact with one another.

[0087] Furthermore, in this embodiment, the central portion P1 includes a p+ region 53 and a p+ region 54 in the substrate 1 instead of the p+ region 13, the n+ region 14, the n+ region 15, and the pn junction region 16 (multiplication region R1). The p+ region 54 contains p-type impurities and has a lower end located on the lower surface of the substrate 1. The p+ region 53 contains p-type impurities and is provided on the p+ region 54. Most of the p+ region 53 is located in the semiconductor layer 12, but the right and left ends of the p+ region 53 are located in the semiconductor layer 11. The right and left ends of the p+ region 53 are located below the lateral isolation region 17 and above the p+ regions 13 in the right portion P2 and the left portion P2. Note that the p+ region 53 in this embodiment is not in contact with the lateral isolation region 17 or the p+ region 13. The cathode electrode CA1 in this embodiment is provided below the p+ region 54.

[0088] In this embodiment, the substrate 1 includes a multiplication region R2 in the right portion P2 and a multiplication region R2 in the left portion P2, but does not include a multiplication region R1 in the central portion P1. The multiplication region R2 in the right portion P2 in this embodiment not only multiplies carriers from the semiconductor layer 11 in the right portion P2, but also multiplies carriers from the semiconductor layer 12 in the central portion P1. Similarly, the multiplication region R2 in the left portion P2 in this embodiment not only multiplies carriers from the semiconductor layer 11 in the left portion P2, but also multiplies carriers from the semiconductor layer 12 in the central portion P1.

[0089] FIG. 10 is a cross-sectional view for explaining the operation of the photodetector of the fourth embodiment.

[0090] Fig. 10 shows the state of the photodetector during SWIR sensing, similar to Fig. 3 (first embodiment). Hereinafter, the operation of the photodetector during SWIR sensing will be described using pixel P shown in Fig. 10 as an example. Note that descriptions of matters common to Fig. 3 and Fig. 10 will be omitted as appropriate.

[0091] During SWIR sensing, the photodetector of this embodiment applies a sufficient bias voltage Vex (≠0 V) to each cathode electrode CA2 of this pixel P, and applies a voltage Vbd to each anode electrode AN of this pixel P. This puts the multiplication region R2 of each portion P2 into a state in which a SPAD reaction can occur. The photodetector of this embodiment further applies a ground voltage GND (=0 V) to the cathode electrode CA1 of this pixel P, generating a potential barrier.

[0092] In this case, the potential of the semiconductor layer 11 is lower than the potential of the semiconductor layer 12, so that carriers generated in the light-receiving region 1a (semiconductor layer 12) of the portion P1 are transferred to each multiplication region R2, as shown in FIG. 10 , causing a SPAD reaction in each multiplication region R2. The carriers generated in the light-receiving region 1a of the portion P1 include photoelectrons indicated by white circles and dark current indicated by black circles. The photodetector of this embodiment detects the carriers via each multiplication region R2 (cathode electrode CA2), thereby detecting SWIR light incident on the pixel P.

[0093] FIG. 11 is another cross-sectional view for explaining the operation of the photodetector of the fourth embodiment.

[0094] Fig. 11 shows the state of the photodetector during NIR sensing, similar to Fig. 4 (first embodiment). Hereinafter, the operation of the photodetector during NIR sensing will be described using pixel P shown in Fig. 11 as an example. Note that descriptions of matters common to Fig. 4 and Fig. 11 will be omitted as appropriate.

[0095] During NIR sensing, the photodetector of this embodiment applies the above-mentioned bias voltage Vex to each cathode electrode CA2 of this pixel P, and applies the above-mentioned voltage Vbd to each anode electrode AN of this pixel P. This puts the multiplication region R2 of each portion P2 into a state in which a SPAD reaction can occur. The photodetector of this embodiment also applies the above-mentioned bias voltage Vex to the cathode electrode CA1 of this pixel P. As a result, no potential barrier is generated, and a drift electric field is formed from the semiconductor layer 12 toward the cathode electrode CA1.

[0096] As a result, carriers generated in the light-receiving region 1a (semiconductor layer 11) of each portion P2 cause a SPAD reaction in the multiplication region R1 of each portion P2, as shown in FIG. 11 . The carriers generated in the light-receiving region 1a of each portion P2 include photoelectrons, indicated by white circles. The photodetector of this embodiment detects the NIR light incident on the pixel P by detecting the carriers via each multiplication region R2 (each cathode electrode CA2).

[0097] 11 further shows carriers generated in the light-receiving region 1a (semiconductor layer 12) of portion P1. The carriers generated in the light-receiving region 1a of portion P1 include photoelectrons indicated by white circles and dark current indicated by black circles. The photodetector of this embodiment detects carriers from the light-receiving region 1a of each portion P2 via each multiplication region R2, while discharging carriers from the light-receiving region 1a of portion P1 via the cathode electrode CA1. Carrier discharge via the cathode electrode CA1 is caused by the drift electric field described above.

[0098] According to this embodiment, by using each multiplication region R2 for carrier detection during both SWIR sensing and NIR sensing, it is possible to perform SWIR sensing and NIR sensing using the same bias voltage Vex, as in the third embodiment. This makes it possible, for example, to simplify the circuit configuration of the photodetector of this embodiment. Furthermore, it is possible to increase the light receiving area 1a of each pixel P and improve the PDE of the SPAD.

[0099] Fifth Embodiment FIG. 12 is a cross-sectional view showing the structure of a photodetector according to a fifth embodiment.

[0100] The photodetector of this embodiment has the same components as the photodetector of the first embodiment (FIG. 1), except that the isolation region 1b of this embodiment has the same shape as the isolation region 1b of the fourth embodiment (FIG. 9).

[0101] Furthermore, in this embodiment, the central portion P1 includes a p++ region 55 in the substrate 1 instead of the p+ region 13. The p++ region 55 contains a higher concentration of p-type impurities than the p+ regions 13 in the right and left portions P2, and is provided on the n+ region 14. The p++ region 55 is located in the semiconductor layer 12, and the right and left ends of the p++ region 55 are located below the lateral isolation region 17. The p++ region 55 is not in contact with the lateral isolation region 17. On the other hand, the right and left ends of the p++ region 55 are in contact with the p+ regions 13 in the right and left portions P2.

[0102] In the central portion P1 of this embodiment, the pn junction region 16 (multiplication region R1) is formed between the n+ region 14 and the p++ region 55. Therefore, unlike the substrate 1 of the fourth embodiment, the substrate 1 of this embodiment includes the multiplication region R1 in the central portion P1 and the multiplication regions R2 in the right and left portions P2. However, the multiplication region R2 in the right portion P2 of this embodiment multiplies carriers not only from the semiconductor layer 11 in the right portion P2 but also from the semiconductor layer 12 in the central portion P1. Similarly, the multiplication region R2 in the left portion P2 of this embodiment multiplies carriers not only from the semiconductor layer 11 in the left portion P2 but also from the semiconductor layer 12 in the central portion P1. In the substrate 1 of this embodiment, the isolation region 1b does not separate the multiplication region R1 in the central portion P1, the multiplication region R2 in the right portion P2, and the multiplication region R2 in the left portion P2 from one another.

[0103] FIG. 13 is a cross-sectional view for explaining the operation of the photodetector of the fifth embodiment.

[0104] Fig. 13 shows the state of the photodetector during SWIR sensing, similar to Fig. 10 (fourth embodiment). Hereinafter, the operation of the photodetector during SWIR sensing will be described using pixel P shown in Fig. 13 as an example. Note that descriptions of matters common to Fig. 10 and Fig. 13 will be omitted as appropriate.

[0105] During SWIR sensing, the photodetector of this embodiment applies a sufficient bias voltage Vex (≠0 V) to each cathode electrode CA2 of this pixel P, and applies a voltage Vbd to each anode electrode AN of this pixel P. This puts the multiplication region R2 of each portion P2 into a state in which a SPAD reaction can occur. The photodetector of this embodiment further applies a ground voltage GND (=0 V) to the cathode electrode CA1 of this pixel P, generating a potential barrier.

[0106] In this case, the potential of the semiconductor layer 11 is lower than the potential of the semiconductor layer 12, so that carriers generated in the light-receiving region 1a (semiconductor layer 12) of the portion P1 are transferred to each multiplication region R2, as shown in FIG. 13 , causing a SPAD reaction in each multiplication region R2. The carriers generated in the light-receiving region 1a of the portion P1 include photoelectrons indicated by white circles and dark current indicated by black circles. The photodetector of this embodiment detects the carriers via each multiplication region R2 (cathode electrode CA2), thereby detecting SWIR light incident on the pixel P.

[0107] FIG. 14 is another cross-sectional view for explaining the operation of the photodetector of the fifth embodiment.

[0108] Fig. 14 shows the state of the photodetector during NIR sensing, similar to Fig. 11 (fourth embodiment). Hereinafter, the operation of the photodetector during NIR sensing will be described using pixel P shown in Fig. 14 as an example. Note that descriptions of matters common to Fig. 11 and Fig. 14 will be omitted as appropriate.

[0109] During NIR sensing, the photodetector of this embodiment applies the above-mentioned bias voltage Vex to each cathode electrode CA2 of this pixel P, and applies the above-mentioned voltage Vbd to each anode electrode AN of this pixel P. This puts the multiplication region R2 of each portion P2 into a state in which a SPAD reaction can occur. The photodetector of this embodiment also applies the above-mentioned bias voltage Vex to the cathode electrode CA1 of this pixel P. As a result, no potential barrier is generated, and a drift electric field is formed from the semiconductor layer 12 toward the cathode electrode CA1.

[0110] As a result, carriers generated in the light-receiving region 1a (semiconductor layer 11) of each portion P2 cause a SPAD reaction in the multiplication region R1 of each portion P2, as shown in FIG. 14. The carriers generated in the light-receiving region 1a of each portion P2 include photoelectrons, indicated by white circles. The photodetector of this embodiment detects the NIR light incident on the pixel P by detecting the carriers via each multiplication region R2 (each cathode electrode CA2).

[0111] FIG. 14 further shows carriers generated in the light-receiving region 1a (semiconductor layer 12) of portion P1. The carriers generated in the light-receiving region 1a of portion P1 include photoelectrons, indicated by white circles, and dark current, indicated by black circles. The photodetector of this embodiment detects carriers from the light-receiving region 1a of each portion P2 via each multiplication region R2, while discharging carriers from the light-receiving region 1a of portion P1 via the cathode electrode CA1. Carrier discharge via the cathode electrode CA1 is caused by the drift electric field described above. Note that the p-type impurity concentration in the p++ region 55 of this embodiment is set to a value such that the multiplication region R1 does not enter a state in which a SPAD reaction can occur at the bias voltage Vex described above.

[0112] According to this embodiment, by using each multiplication region R2 for carrier detection during both SWIR sensing and NIR sensing, it is possible to perform SWIR sensing and NIR sensing using the same bias voltage Vex, as in the third and fourth embodiments. This makes it possible, for example, to simplify the circuit configuration of the photodetector of this embodiment. Furthermore, it is possible to increase the light receiving area 1a of each pixel P and improve the PDE of the SPAD.

[0113] Sixth Embodiment FIG. 15 is a cross-sectional view showing the structure of a photodetector according to a sixth embodiment.

[0114] The photodetector of this embodiment includes, in addition to the components of the photodetector of the fourth embodiment ( FIG. 9 ), an insulating film 56 and a light-shielding layer 57 provided in each upper isolation region 18 near the boundary between portions P1 and P2. The light-shielding layer 57 is, for example, a metal layer having a light-shielding effect. The light-shielding layer 57 is embedded, via the insulating film 56, in a trench formed from the upper surface of the substrate 1 so as not to penetrate the substrate 1 in the Z direction. The functions of the insulating film 56 and the light-shielding layer 57 are generally the same as those of the insulating film 51 and the light-shielding layer 52 of the second embodiment.

[0115] The light-shielding layer 57 of this embodiment is provided so as not to separate the light-receiving region 1a in the center portion P1 from the light-receiving regions 1a in the right portion P2 and the left portion P2. This makes it possible to restrict, to some extent, the movement of carriers between these portions P1 and P2, thereby making it possible to suppress deterioration of the DCR. Note that if the light-shielding effect of the light-shielding layer 57 is not necessary, the photodetector of this embodiment may be provided with a metal layer that does not have a light-shielding effect instead of the light-shielding layer 57.

[0116] FIG. 16 is a cross-sectional view showing the structure of a photodetector according to a modified example of the sixth embodiment.

[0117] The photodetector of this modification includes, in addition to the components of the photodetector of the fifth embodiment ( FIG. 12 ), an insulating film 56 and a light-shielding layer 57 provided in each upper isolation region 18 near the boundary between portions P1 and P2. The shape, material, function, etc. of the insulating film 56 and the light-shielding layer 57 of this modification are the same as those of the fifth embodiment ( FIG. 15 ). According to this modification, it is possible to obtain the same effects as those of the sixth embodiment.

[0118] Seventh Embodiment FIG. 17 is a cross-sectional view showing the structure of a photodetector according to a seventh embodiment.

[0119] The photodetector of this embodiment has the same components as the photodetector of the first embodiment ( FIG. 1 ). However, the lower end (lower surface) of the semiconductor layer 12 of this embodiment is not located higher than the lower surface of the substrate 1, but is located on the lower surface of the substrate 1. Therefore, the boundary (interface) between the semiconductor layer 11 and the semiconductor layer 12 of this embodiment does not exist below the semiconductor layer 12.

[0120] The interface between the semiconductor layer 11 and the semiconductor layer 12 generally contains a large number of defects. According to this embodiment, it is possible to reduce the area of ​​the interface between the semiconductor layer 11 and the semiconductor layer 12, thereby reducing the number of defects in each pixel P. Furthermore, according to this embodiment, it is possible to improve the PDE of the SPAD by increasing the size of the semiconductor layer 12 in each pixel P.

[0121] FIG. 18 is a cross-sectional view showing the structure of a photodetector according to a first modified example of the seventh embodiment.

[0122] The photodetector of this modification has the same components as the photodetector of the fourth embodiment ( FIG. 9 ). However, the lower end of the semiconductor layer 12 of this modification is located on the lower surface of the substrate 1, not higher than the lower surface of the substrate 1. Therefore, the boundary between the semiconductor layer 11 and the semiconductor layer 12 of this modification does not exist below the semiconductor layer 12. According to this modification, it is possible to obtain the same effects as those of the seventh embodiment ( FIG. 17 ).

[0123] FIG. 19 is a cross-sectional view showing the structure of a photodetector according to a second modified example of the seventh embodiment.

[0124] The photodetector of this modification has the same components as the photodetector of the fifth embodiment ( FIG. 12 ). However, the lower end of the semiconductor layer 12 of this modification is located on the lower surface of the substrate 1, not higher than the lower surface of the substrate 1. Therefore, the boundary between the semiconductor layer 11 and the semiconductor layer 12 of this modification does not exist below the semiconductor layer 12. According to this modification, it is possible to obtain the same effects as those of the seventh embodiment ( FIG. 17 ).

[0125] Eighth Embodiment FIG. 20 is a cross-sectional view showing the structure of a photodetector according to an eighth embodiment.

[0126] The photodetector of this embodiment has the same components as the photodetector of the first embodiment ( FIG. 1 ). However, each pixel P of this embodiment includes one portion P1 and one portion P2, as shown in FIG. 20 . Furthermore, the semiconductor layer 12 of this embodiment is provided in the portion P1 and the portion P2 within each pixel P. In each pixel P of this embodiment, the semiconductor layer 12 is located in the vertical direction of the semiconductor layer 11, specifically, below the semiconductor layer 11.

[0127] In the portion P1 of this embodiment, a p+ region 13, an n+ region 14, and a pn junction region 16 (multiplication region R1) are provided in the semiconductor layer 12. The portion P1 of this embodiment does not include the n+ region 15. The cathode electrode CA1 of this embodiment is provided below the n+ region 14 of the portion P1. The multiplication region R1 of this embodiment is disposed below the thick lens 31, as shown in FIG. 20 .

[0128] In portion P2 of this embodiment, p+ region 13, n+ region 14, n+ region 15 (part), and pn junction region 16 (multiplication region R2) are provided in semiconductor layer 11, and n+ region 15 (remaining part) is provided in semiconductor layer 12. Cathode electrode CA2 of this embodiment is provided below n+ region 15 of portion P2. Multiplication region R2 of this embodiment is disposed below thin lens 31, as shown in FIG. 20 .

[0129] FIG. 21 is a horizontal cross-sectional view showing the structure of the photodetector according to the eighth embodiment.

[0130] Fig. 21A shows a cross section taken along line A-A' in Fig. 20. Fig. 21A shows a cross section of semiconductor layer 11. Fig. 21A also shows a cross section of n+ region 14 in portion P2. Note that Fig. 20 shows a cross section taken along line CC' in Fig. 21A.

[0131] Figure 21B shows a cross section taken along line BB' shown in Figure 20. Figure 21B mainly shows a cross section of semiconductor layer 12. Figure 21B also shows cross sections of n+ region 15 in portion P2 and n+ region 14 in portion P1. Note that Figure 20 shows a cross section taken along line DD' shown in Figure 21A.

[0132] FIG. 22 is a cross-sectional view for explaining the operation of the photodetector of the eighth embodiment.

[0133] 22 shows the state of the photodetector during SWIR sensing, similar to Fig. 3 (first embodiment). The operation of the photodetector of this embodiment during SWIR sensing is similar to that of the first embodiment.

[0134] FIG. 23 is another cross-sectional view for explaining the operation of the photodetector of the eighth embodiment.

[0135] 23 shows the state of the photodetector during NIR sensing, similar to Fig. 4 (first embodiment). The operation of the photodetector of this embodiment during NIR sensing is similar to that of the first embodiment.

[0136] According to this embodiment, by arranging the semiconductor layer 12 in the vertical direction of the semiconductor layer 11, it is possible to shrink the size of each pixel P in a plan view.

[0137] 24 is a block diagram showing the configuration of a distance measuring device according to a ninth embodiment. The distance measuring device according to this embodiment includes an illuminance sensor 61, an MCU (Micro Controller Unit) 62, a light emitting device 63, and a light detecting device (light receiving device) 64. The MCU 62 is an example of a control mechanism according to the present disclosure.

[0138] The photodetector 64 corresponds to any one of the photodetector devices of the first to eighth embodiments. Therefore, the photodetector 64 includes a plurality of pixels P, and FIG. 24 shows one of these pixels P. Each pixel P in this embodiment includes one portion P1 and one portion P2. In this embodiment, the portion P1 is used for detecting SWIR light, and the portion P2 is used for detecting NIR light. Note that each pixel P in this embodiment may include a plurality of portions P2.

[0139] The light emitting device 63 includes a laser diode 63a and a laser diode 63b. In this embodiment, the laser diode 63a emits SWIR light, and the laser diode 63b emits NIR light.

[0140] The illuminance sensor 61 detects illuminance and outputs the illuminance detection result to the MCU 62. The illuminance sensor 61 of this embodiment detects the illuminance in the environment in which the distance measuring device of this embodiment is placed. For example, if the distance measuring device is placed outdoors, the illuminance sensor 61 detects illuminance caused by sunlight, etc. If the distance measuring device is placed indoors, the illuminance sensor 61 detects illuminance caused by lighting fixtures, etc.

[0141] The MCU 62 controls the operation of the distance measuring device of this embodiment. For example, the MCU 62 controls the light emitting device 63 and the light detecting device 64 based on the illuminance detected by the illuminance sensor 61 to measure the distance between the distance measuring device and the subject S. The control unit 42 ( FIG. 2 ) described above may be a part of the MCU 62, or conversely, the MCU 62 may be a part of the control unit 42 described above.

[0142] If the illuminance is higher than a predetermined value, the MCU 62 causes the laser diode 63a to emit SWIR light. This SWIR light is irradiated onto the subject S, reflected by the subject S, and received by the portion P1. The readout circuit 64a in the photodetector 64 reads out the carriers generated in the portion P1 and outputs the carrier readout result to the MCU 62. The MCU 62 measures the distance to the subject S based on the carrier readout result by the readout circuit 64a. In this case, the carrier readout by the readout circuit 64a is performed using the carrier detection method described in, for example, Figures 3, 10, 13, 22, etc. The illuminance value higher than the predetermined value is an example of the second value in the present disclosure.

[0143] If the illuminance is lower than the predetermined value, the MCU 62 causes the laser diode 63b to emit NIR light. This NIR light is irradiated onto the subject S, reflected by the subject S, and received by the portion P2. The readout circuit 64a in the photodetector 64 reads out the carriers generated in the portion P2 and outputs the carrier readout result to the MCU 62. The MCU 62 measures the distance to the subject S based on the carrier readout result by the readout circuit 64a. In this case, the carrier readout by the readout circuit 64a is performed using the carrier detection method described in, for example, Figures 4, 11, 14, and 23. The illuminance value lower than the predetermined value is an example of the first value in the present disclosure.

[0144] According to this embodiment, it is possible to perform suitable distance measurement using a photodetector 64 that corresponds to any of the photodetectors of the first to eighth embodiments.

[0145] Tenth Embodiment FIG. 25 is a block diagram showing the configuration of a distance measuring device according to a tenth embodiment.

[0146] The distance measuring device of this embodiment has the same components as the distance measuring device of the ninth embodiment ( FIG. 24 ). As shown in FIG. 25 , the photodetector 64 of this embodiment has a plurality of pixels P arranged in a two-dimensional array. As in the ninth embodiment, each pixel P includes one portion P1 and one portion P2. The structures of the portions P1 and P2 of this embodiment are the same as the portions P1 and P2 of any of the first to eighth embodiments. In FIG. 25 , the portions P1 and P2 of the plurality of pixels P are arranged in a checkerboard pattern. Note that each pixel P of this embodiment may include a plurality of portions P2.

[0147] 25, the photodetector 64 of this embodiment includes the above-described readout circuit 64a, row selection circuit 64b, and filter 64c. The row selection circuit 64b selects a row to be read. The row selection circuit 64b further selects a portion P1 or portion P2 to be read within the selected row by specifying the address of the portion P1 or portion P2 to be read. The readout circuit 64a reads carriers generated in the selected portion P1 or portion P2.

[0148] The filter 64c is arranged to allow light of a predetermined wavelength to be incident on the portions P1 and P2 of each pixel P. Examples of the filter 64c include a long-pass filter that transmits light having a wavelength of 940 nm or more, and a dual band-pass filter that transmits light having a wavelength of 940 to 1300 nm.

[0149] According to this embodiment, it is possible to perform more suitable distance measurement using a photodetector 64 that corresponds to any of the photodetectors of the first to eighth embodiments.

[0150] Eleventh Embodiment Fig. 26 is a block diagram showing the configuration of a vehicle 101 according to an eleventh embodiment. Fig. 26 shows an example of the configuration of a vehicle control system 111, which is an example of a mobility device control system.

[0151] The vehicle control system 111 is provided in the vehicle 101 and performs processing related to driving assistance and automatic driving of the vehicle 101.

[0152] The vehicle control system 111 includes a vehicle control ECU (Electronic Control Unit) 121, a communication unit 122, a map information storage unit 123, a position information acquisition unit 124, an external recognition sensor 125, an in-vehicle sensor 126, a vehicle sensor 127, a storage unit 131, a driving assistance / autonomous driving control unit 132, a DMS (Driver Monitoring System) 133, an HMI (Human Machine Interface) 134, and a vehicle control unit 135. The external recognition sensor 125 includes, for example, the distance measuring device of the ninth or tenth embodiment.

[0153] The vehicle control ECU 121, communication unit 122, map information storage unit 123, position information acquisition unit 124, external recognition sensor 125, in-vehicle sensor 126, vehicle sensor 127, memory unit 131, cruise assist / autonomous driving control unit 132, driver monitoring system (DMS) 133, human-machine interface (HMI) 134, and vehicle control unit 135 are connected to each other via a communication network 141 so as to be able to communicate with each other. The communication network 141 is configured, for example, by an in-vehicle communication network or bus conforming to a digital two-way communication standard such as a controller area network (CAN), a local interconnect network (LIN), a local area network (LAN), FlexRay (registered trademark), or Ethernet (registered trademark). The communication network 141 may be used differently depending on the type of data being transmitted. For example, a CAN may be used for data related to vehicle control, and an Ethernet may be used for large-volume data. In addition, each part of the vehicle control system 111 may be directly connected without going through the communication network 141, using wireless communication intended for communication over relatively short distances, such as near field communication (NFC) or Bluetooth (registered trademark).

[0154] In the following description, when each unit of the vehicle control system 111 communicates via the communication network 141, the description of the communication network 141 will be omitted. For example, when the vehicle control ECU 121 and the communication unit 122 communicate via the communication network 141, it will simply be described as the vehicle control ECU 121 and the communication unit 122 communicating with each other.

[0155] [Vehicle Control ECU 121] The vehicle control ECU 121 is configured by various processors such as a CPU (Central Processing Unit), an MPU (Micro Processing Unit), etc. The vehicle control ECU 121 controls the entire or part of the functions of the vehicle control system 111.

[0156] [Communication Unit 122] The communication unit 122 communicates with various devices inside and outside the vehicle, other vehicles, servers, base stations, etc., and transmits and receives various types of data. At this time, the communication unit 122 can communicate using multiple communication methods.

[0157] The following provides an overview of communication with the outside of the vehicle that can be performed by the communication unit 122. The communication unit 122 communicates with a server (hereinafter referred to as an external server) or the like present on an external network via a base station or an access point using a wireless communication method such as 5G (fifth generation mobile communication system), LTE (Long Term Evolution), or DSRC (Dedicated Short Range Communications). The external network with which the communication unit 122 communicates is, for example, the Internet, a cloud network, or a network specific to a carrier. The communication method used by the communication unit 122 with the external network is not particularly limited as long as it is a wireless communication method that enables digital two-way communication at a communication speed equal to or higher than a predetermined distance.

[0158] Furthermore, for example, the communication unit 122 can communicate with a terminal located near the vehicle using P2P (Peer to Peer) technology. The terminal located near the vehicle can be, for example, a terminal worn by a mobile object moving at a relatively slow speed, such as a pedestrian or a bicycle, a terminal installed at a fixed location in a store, or an MTC (Machine Type Communication) terminal. Furthermore, the communication unit 122 can also perform V2X communication. V2X communication refers to communication between the vehicle and others, such as vehicle-to-vehicle (V2X) communication with another vehicle, vehicle-to-infrastructure (V2X) communication with a roadside unit, vehicle-to-home (V2X) communication with a home, and vehicle-to-pedestrian (V2X) communication with a terminal carried by a pedestrian.

[0159] The communication unit 122 can receive, for example, a program for updating software that controls the operation of the vehicle control system 111 from the outside (over the air). The communication unit 122 can also receive map information, traffic information, information about the surroundings of the vehicle 101, and the like from the outside. For example, the communication unit 122 can also transmit information about the vehicle 101 and information about the surroundings of the vehicle 101 to the outside. Information about the vehicle 101 that the communication unit 122 transmits to the outside includes, for example, data indicating the status of the vehicle 101 and the recognition result by the recognition unit 173. Furthermore, for example, the communication unit 122 performs communication corresponding to a vehicle emergency notification system such as e-call.

[0160] For example, the communication unit 122 receives electromagnetic waves transmitted by a road traffic information and communication system (VICS (Vehicle Information and Communication System) (registered trademark)) such as a radio beacon, an optical beacon, or FM multiplex broadcasting.

[0161] The following provides an overview of communication with the vehicle interior that can be performed by the communication unit 122. The communication unit 122 can communicate with each device in the vehicle using, for example, wireless communication. The communication unit 122 can communicate with each device in the vehicle using a communication method that enables bidirectional digital communication at a predetermined communication speed or higher via wireless communication, such as wireless LAN, Bluetooth, NFC, or Wireless USB (WUSB). The communication unit 122 can also communicate with each device in the vehicle using wired communication. For example, the communication unit 122 can communicate with each device in the vehicle using wired communication via a cable connected to a connection terminal (not shown). The communication unit 122 can communicate with each device in the vehicle using a communication method that enables bidirectional digital communication at a predetermined communication speed or higher via wired communication, such as Universal Serial Bus (USB), High-Definition Multimedia Interface (HDMI) (registered trademark), or Mobile High-Definition Link (MHL).

[0162] Here, the in-vehicle device refers to, for example, a device in the vehicle that is not connected to the communication network 141. Possible in-vehicle devices include, for example, a mobile device or a wearable device carried by a passenger such as a driver, and an information device brought into the vehicle and temporarily installed therein.

[0163] [Map Information Storage Unit 123] The map information storage unit 123 stores one or both of a map acquired from an external source and a map created by the vehicle 101. For example, the map information storage unit 123 stores a three-dimensional high-precision map, a global map that is less accurate than a high-precision map and covers a wide area, and the like.

[0164] Examples of high-precision maps include dynamic maps, point cloud maps, and vector maps. A dynamic map is a map consisting of four layers of dynamic information, quasi-dynamic information, quasi-static information, and static information, and is provided to the vehicle 101 from an external server or the like. A point cloud map is a map made up of a point cloud (point group data). A vector map is a map that associates traffic information such as the positions of lanes and traffic lights with the point cloud map, and is adapted to an advanced driver assistance system (ADAS) or autonomous driving (AD).

[0165] The point cloud map and the vector map may be provided, for example, from an external server or the like, or may be created by the vehicle 101 based on sensing results from the camera 151, radar 152, LiDAR 153, etc. as a map for matching with a local map described later, and stored in the map information storage unit 123. Furthermore, when a high-precision map is provided from an external server or the like, map data of, for example, an area of ​​several hundred square meters related to the planned route along which the vehicle 101 will travel is acquired from the external server or the like in order to reduce communication capacity.

[0166] [Location Information Acquisition Unit 124] The location information acquisition unit 124 receives GNSS (Global Navigation Satellite System) signals from satellites and acquires location information of the vehicle 101. The acquired location information is supplied to the driving assistance / autonomous driving control unit 132. Note that the location information acquisition unit 124 is not limited to a method using GNSS signals, and may acquire location information using a beacon, for example.

[0167] [External Recognition Sensor 125] The external recognition sensor 125 includes various sensors used to recognize the situation outside the vehicle 101, and supplies sensor data from each sensor to each part of the vehicle control system 111. The type and number of sensors included in the external recognition sensor 125 are arbitrary.

[0168] For example, the external recognition sensor 125 includes a camera 151, a radar 152, a LiDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) 153, and an ultrasonic sensor 154. Without being limited to this, the external recognition sensor 125 may be configured to include one or more types of sensors selected from the camera 151, the radar 152, the LiDAR 153, and the ultrasonic sensor 154. The number of cameras 151, radars 152, LiDARs 153, and ultrasonic sensors 154 is not particularly limited as long as the number is a number that can be realistically installed on the vehicle 101. Furthermore, the types of sensors included in the external recognition sensor 125 are not limited to this example, and the external recognition sensor 125 may include other types of sensors. Examples of sensing areas of the sensors included in the external recognition sensor 125 will be described later.

[0169] The imaging method of the camera 151 is not particularly limited. For example, cameras of various imaging methods, such as a time-of-flight (ToF) camera, a stereo camera, a monocular camera, and an infrared camera, which are imaging methods capable of distance measurement, can be applied to the camera 151 as needed. However, the camera 151 may simply acquire a photographed image without being related to distance measurement.

[0170] Furthermore, for example, the external recognition sensor 125 may include an environmental sensor for detecting the environment of the vehicle 101. The environmental sensor is a sensor for detecting the environment such as weather, climate, brightness, etc., and may include various sensors such as a raindrop sensor, a fog sensor, a sunlight sensor, a snow sensor, and an illuminance sensor.

[0171] Furthermore, for example, the external recognition sensor 125 includes a microphone used to detect sounds around the vehicle 101 and the location of sound sources.

[0172] [In-vehicle sensor 126] The in-vehicle sensor 126 includes various sensors for detecting information inside the vehicle, and supplies sensor data from each sensor to each unit of the vehicle control system 111. The types and number of the various sensors included in the in-vehicle sensor 126 are not particularly limited as long as they are of types and numbers that can be realistically installed in the vehicle 101.

[0173] For example, the interior sensor 126 may include one or more types of sensors selected from the group consisting of a camera, radar, a seating sensor, a steering wheel sensor, a microphone, and a biometric sensor. The camera included in the interior sensor 126 may be a camera using any of various imaging methods capable of measuring distances, such as a Time of Flight (ToF) camera, a stereo camera, a monocular camera, or an infrared camera. The camera included in the interior sensor 126 may also be a camera simply for acquiring captured images, regardless of distance measurement. The biometric sensor included in the interior sensor 126 is provided, for example, on a seat, a steering wheel, or the like, and detects various types of biometric information of a passenger, such as a driver.

[0174] [Vehicle Sensor 127] The vehicle sensor 127 includes various sensors for detecting the state of the vehicle 101, and supplies sensor data from each sensor to each unit of the vehicle control system 111. The types and number of the various sensors included in the vehicle sensor 127 are not particularly limited as long as they are of the types and number that can be realistically installed on the vehicle 101.

[0175] For example, the vehicle sensor 127 includes a speed sensor, an acceleration sensor, an angular velocity sensor (gyro sensor), and an inertial measurement unit (IMU) that integrates these sensors. For example, the vehicle sensor 127 includes a steering angle sensor that detects the steering angle of the steering wheel, a yaw rate sensor, an accelerator sensor that detects the amount of accelerator pedal operation, and a brake sensor that detects the amount of brake pedal operation. For example, the vehicle sensor 127 includes a rotation sensor that detects the number of rotations of the engine or motor, an air pressure sensor that detects tire air pressure, a slip ratio sensor that detects tire slip ratio, and a wheel speed sensor that detects the rotation speed of the wheels. For example, the vehicle sensor 127 includes a battery sensor that detects the remaining battery charge and temperature, and an impact sensor that detects external impacts.

[0176] [Storage Unit 131] The storage unit 131 includes at least one of a non-volatile storage medium and a volatile storage medium, and stores data and programs. The storage unit 131 is used, for example, as an electrically erasable programmable read-only memory (EEPROM) and a random access memory (RAM). Examples of storage media that can be used include a magnetic storage device such as a hard disk drive (HDD), a semiconductor storage device, an optical storage device, and a magneto-optical storage device. The storage unit 131 stores various programs and data used by each component of the vehicle control system 111. For example, the storage unit 131 includes an event data recorder (EDR) and a data storage system for automated driving (DSSAD), and stores information about the vehicle 101 before and after an event such as an accident, and information acquired by the in-vehicle sensor 126.

[0177] [Driving assistance / autonomous driving control unit 132] The driving assistance / autonomous driving control unit 132 controls driving assistance and autonomous driving of the vehicle 101. For example, the driving assistance / autonomous driving control unit 132 includes an analysis unit 161, an action planning unit 162, and an operation control unit 163.

[0178] The analysis unit 161 performs an analysis process of the vehicle 101 and the surrounding situation. The analysis unit 161 includes a self-position estimation unit 171, a sensor fusion unit 172, and a recognition unit 173.

[0179] The self-position estimation unit 171 estimates the self-position of the vehicle 101 based on sensor data from the external recognition sensor 125 and a high-precision map stored in the map information storage unit 123. For example, the self-position estimation unit 171 generates a local map based on the sensor data from the external recognition sensor 125 and matches the local map with the high-precision map to estimate the self-position of the vehicle 101. The position of the vehicle 101 is based on, for example, the center of the rear wheel pair axle.

[0180] The local map is, for example, a three-dimensional high-precision map or an occupancy grid map created using a technology such as SLAM (Simultaneous Localization and Mapping). The three-dimensional high-precision map is, for example, the point cloud map described above. The occupancy grid map is a map in which the three-dimensional or two-dimensional space around the vehicle 101 is divided into grids of a predetermined size and the occupancy status of objects is indicated on a grid-by-grid basis. The occupancy status of an object is indicated, for example, by the presence or absence of an object and its probability of existence. The local map is also used, for example, in the detection process and recognition process of the situation outside the vehicle 101 by the recognition unit 173.

[0181] The self-position estimation unit 171 may estimate the self-position of the vehicle 101 based on the position information acquired by the position information acquisition unit 124 and the sensor data from the vehicle sensor 127 .

[0182] The sensor fusion unit 172 performs sensor fusion processing to obtain new information by combining multiple different types of sensor data (for example, image data supplied from the camera 151 and sensor data supplied from the radar 152). Methods for combining different types of sensor data include integration, fusion, and association.

[0183] The recognition unit 173 executes a detection process for detecting the situation outside the vehicle 101 and a recognition process for recognizing the situation outside the vehicle 101 .

[0184] For example, the recognition unit 173 performs detection processing and recognition processing of the external situation of the vehicle 101 based on information from the external recognition sensor 125, information from the self-position estimation unit 171, information from the sensor fusion unit 172, etc.

[0185] Specifically, for example, the recognition unit 173 performs detection processing and recognition processing of objects around the vehicle 101. The object detection processing is, for example, processing to detect the presence or absence, size, shape, position, movement, etc. of an object. The object recognition processing is, for example, processing to recognize attributes such as the type of object, or to identify a specific object. However, the detection processing and the recognition processing are not necessarily clearly separated, and may overlap.

[0186] For example, the recognition unit 173 detects objects around the vehicle 101 by performing clustering to classify a point cloud based on sensor data from the radar 152, the LiDAR 153, or the like into clusters of points. This allows the presence, size, shape, and position of objects around the vehicle 101 to be detected.

[0187] For example, the recognition unit 173 performs tracking to follow the movement of clusters of point clouds classified by clustering, thereby detecting the movement of objects around the vehicle 101. As a result, the speed and traveling direction (movement vector) of the objects around the vehicle 101 are detected.

[0188] For example, the recognition unit 173 detects or recognizes vehicles, people, bicycles, obstacles, structures, roads, traffic lights, traffic signs, road markings, etc. based on image data supplied from the camera 151. Furthermore, the recognition unit 173 may recognize the type of object around the vehicle 101 by performing recognition processing such as semantic segmentation.

[0189] For example, the recognition unit 173 can perform recognition processing of traffic rules around the vehicle 101 based on the map stored in the map information storage unit 123, the estimation result of the self-position by the self-position estimation unit 171, and the recognition result of the recognition unit 173 of objects around the vehicle 101. Through this processing, the recognition unit 173 can recognize the positions and states of traffic lights, the contents of traffic signs and road markings, the contents of traffic regulations, and lanes that can be driven on.

[0190] For example, the recognition unit 173 can perform a recognition process of the environment around the vehicle 101. The surrounding environment to be recognized by the recognition unit 173 may include weather, temperature, humidity, brightness, and road surface conditions.

[0191] The behavior planning unit 162 creates a behavior plan for the vehicle 101. For example, the behavior planning unit 162 creates the behavior plan by performing route planning and route tracking processing.

[0192] Global path planning is a process for planning a rough route from the start to the goal. This route planning also includes a process for generating a trajectory (local path planning) that allows the vehicle 101 to travel safely and smoothly in the vicinity of the vehicle 101, taking into account the motion characteristics of the vehicle 101 on the planned route.

[0193] Path following is a process of planning an operation for safely and accurately traveling along a route planned by a route plan within a planned time. The behavior planning unit 162 can calculate a target speed and a target angular velocity of the vehicle 101 based on the results of the path following process, for example.

[0194] The operation control unit 163 controls the operation of the vehicle 101 in order to realize the action plan created by the action planning unit 162 .

[0195] For example, the operation control unit 163 controls the steering control unit 181, the brake control unit 182, and the drive control unit 183 included in the vehicle control unit 135 described later, to perform acceleration / deceleration control and direction control so that the vehicle 101 travels along the trajectory calculated by the trajectory plan. For example, the operation control unit 163 performs cooperative control with the aim of realizing ADAS functions such as collision avoidance or impact mitigation, following driving, vehicle speed maintenance driving, collision warning for the host vehicle, and lane departure warning for the host vehicle. For example, the operation control unit 163 performs cooperative control with the aim of automatic driving, which drives autonomously without driver operation.

[0196] [DMS 133] The DMS 133 performs processes such as authenticating the driver and recognizing the driver's state based on sensor data from the in-vehicle sensor 126 and input data input to the HMI 134 (described later). Examples of the driver's state to be recognized include physical condition, alertness, concentration, fatigue, gaze direction, level of intoxication, driving operation, and posture.

[0197] The DMS 133 may be configured to perform authentication processing for passengers other than the driver and recognition processing for the conditions of the passengers. Furthermore, for example, the DMS 133 may be configured to perform recognition processing for the conditions inside the vehicle based on sensor data from the in-vehicle sensor 126. Possible conditions inside the vehicle to be recognized include, for example, temperature, humidity, brightness, and odor.

[0198] [HMI 134] The HMI 134 receives input of various data and instructions, and presents various data to the driver and the like.

[0199] The following provides an overview of data input via the HMI 134. The HMI 134 includes an input device for a person to input data. The HMI 134 generates input signals based on data, instructions, and the like input via the input device and supplies the signals to each component of the vehicle control system 111. The HMI 134 includes, as input devices, controls such as a touch panel, buttons, switches, and levers. The HMI 134 may also include input devices that allow information to be input by voice, gestures, or other means other than manual operation. Furthermore, the HMI 134 may use, as input devices, externally connected devices such as a remote control device using infrared or radio waves, or a mobile or wearable device compatible with the operation of the vehicle control system 111.

[0200] The presentation of data by the HMI 134 will be briefly described. The HMI 134 generates visual information, auditory information, and tactile information for the occupant or the outside of the vehicle. The HMI 134 also performs output control, controlling the output, output content, output timing, output method, etc. of each piece of generated information. The HMI 134 generates and outputs, as visual information, information indicated by images or lights, such as an operation screen, a status display of the vehicle 101, a warning display, and a monitor image showing the situation around the vehicle 101. The HMI 134 also generates and outputs, as auditory information, information indicated by sounds, such as voice guidance, warning sounds, and warning messages. The HMI 134 also generates and outputs, as tactile information, information imparted to the occupant's sense of touch by force, vibration, movement, etc.

[0201] Examples of output devices that the HMI 134 uses to output visual information include a display device that displays an image on its own to present visual information and a projector device that projects an image to present visual information. The display device may be a device that displays visual information within the passenger's field of view, such as a head-up display, a transmissive display, or a wearable device with an augmented reality (AR) function, in addition to a display device having a normal display. The HMI 134 may also use display devices included in a navigation system, an instrument panel, a camera monitoring system (CMS), an electronic mirror, a lamp, or the like provided in the vehicle 101 as output devices that output visual information.

[0202] As an output device for the HMI 134 to output auditory information, for example, an audio speaker, a headphone, or an earphone can be applied.

[0203] For example, a haptic element using haptic technology can be applied as an output device for outputting tactile information from the HMI 134. The haptic element is provided on a part of the vehicle 101 that is in contact with a passenger, such as a steering wheel or a seat.

[0204] [Vehicle Control Unit 135] The vehicle control unit 135 controls each unit of the vehicle 101. The vehicle control unit 135 includes a steering control unit 181, a brake control unit 182, a drive control unit 183, a body system control unit 184, a light control unit 185, and a horn control unit 186.

[0205] The steering control unit 181 detects and controls the state of the steering system of the vehicle 101. The steering system includes, for example, a steering mechanism including a steering wheel, an electric power steering, etc. The steering control unit 181 includes, for example, a steering ECU that controls the steering system, an actuator that drives the steering system, etc.

[0206] The brake control unit 182 detects and controls the state of the brake system of the vehicle 101. The brake system includes, for example, a brake mechanism including a brake pedal, an antilock brake system (ABS), a regenerative brake mechanism, etc. The brake control unit 182 includes, for example, a brake ECU that controls the brake system, an actuator that drives the brake system, etc.

[0207] The drive control unit 183 detects and controls the state of the drive system of the vehicle 101. The drive system includes, for example, an accelerator pedal, a drive force generating device for generating drive force such as an internal combustion engine or a drive motor, and a drive force transmission mechanism for transmitting the drive force to the wheels. The drive control unit 183 includes, for example, a drive ECU for controlling the drive system, and an actuator for driving the drive system.

[0208] The body system control unit 184 detects and controls the states of the body system systems of the vehicle 101. The body system systems include, for example, a keyless entry system, a smart key system, a power window device, a power seat, an air conditioning system, an airbag, a seat belt, a shift lever, etc. The body system control unit 184 includes, for example, a body system ECU that controls the body system systems, an actuator that drives the body system systems, etc.

[0209] The light control unit 185 detects and controls the states of various lights of the vehicle 101. Examples of lights to be controlled include headlights, backlights, fog lights, turn signals, brake lights, projections, and bumper displays. The light control unit 185 includes a light ECU that controls the lights, an actuator that drives the lights, and the like.

[0210] The horn control unit 186 detects and controls the state of the car horn of the vehicle 101. The horn control unit 186 includes, for example, a horn ECU that controls the car horn, an actuator that drives the car horn, and the like.

[0211] Fig. 27 is a plan view showing a sensing area of ​​the vehicle 101 of the eleventh embodiment. Fig. 27 shows an example of a sensing area by the camera 151, radar 152, LiDAR 153, ultrasonic sensor 154, etc. of the external recognition sensor 125 of Fig. 26. Note that Fig. 27 schematically shows the vehicle 101 as seen from above, with the left end side being the front end (front) side of the vehicle 101 and the right end side being the rear end (rear) side of the vehicle 101.

[0212] [Sensing Areas 1-1F, 1-1B] Sensing area 1-1F and sensing area 1-1B are examples of sensing areas of the ultrasonic sensors 154. Sensing area 1-1F covers the periphery of the front end of the vehicle 101 with multiple ultrasonic sensors 154. Sensing area 1-1B covers the periphery of the rear end of the vehicle 101 with multiple ultrasonic sensors 154.

[0213] The sensing results in the sensing area 1-1F and the sensing area 1-1B are used, for example, for parking assistance for the vehicle 101.

[0214] [Sensing Areas 1-2F, B, L, R] Sensing area 1-2F to sensing area 1-2B show examples of sensing areas of a short-range or medium-range radar 152. Sensing area 1-2F covers a position farther in front of the vehicle 101 than sensing area 1-1F. Sensing area 1-2B covers a position farther behind the vehicle 101 than sensing area 1-1B. Sensing area 1-2L covers the periphery behind the left side of the vehicle 101. Sensing area 1-2R covers the periphery behind the right side of the vehicle 101.

[0215] The sensing results in sensing area 1-2F are used, for example, to detect vehicles, pedestrians, etc. that are present in front of the vehicle 101. The sensing results in sensing area 1-2B are used, for example, for collision prevention functions behind the vehicle 101. The sensing results in sensing area 1-2L and sensing area 1-2R are used, for example, to detect objects in blind spots on the sides of the vehicle 101.

[0216] [Sensing Areas 1-3F, B, L, R] Sensing area 1-3F to sensing area 1-3B show examples of sensing areas sensed by camera 151. Sensing area 1-3F covers a position farther in front of the vehicle 101 than sensing area 1-2F. Sensing area 1-3B covers a position farther in the rear of the vehicle 101 than sensing area 1-2B. Sensing area 1-3L covers the periphery of the left side of the vehicle 101. Sensing area 1-3R covers the periphery of the right side of the vehicle 101.

[0217] The sensing results in sensing area 1-3F can be used, for example, for recognizing traffic lights and traffic signs, lane departure prevention assistance systems, and automatic headlight control systems. The sensing results in sensing area 1-3B can be used, for example, for parking assistance and surround view systems. The sensing results in sensing area 1-3L and sensing area 1-3R can be used, for example, for surround view systems.

[0218] [Sensing area 1-4] Sensing area 1-4 shows an example of the sensing area of ​​LiDAR 153. Sensing area 1-4 covers a position farther ahead of vehicle 101 than sensing area 1-3F. On the other hand, sensing area 1-4 has a narrower range in the left-right direction than sensing area 1-3F.

[0219] The sensing results in the sensing areas 1-4 are used to detect objects such as surrounding vehicles, for example.

[0220] [Sensing area 1-5] Sensing area 1-5 shows an example of the sensing area of ​​the long-range radar 152. Sensing area 1-5 covers a position further ahead of the vehicle 101 than sensing area 1-4. On the other hand, sensing area 1-5 has a narrower range in the left-right direction than sensing area 1-4.

[0221] The sensing results in the sensing areas 1-5 are used for, for example, adaptive cruise control (ACC), emergency braking, collision avoidance, and the like.

[0222] The sensing areas of the cameras 151, radar 152, LiDAR 153, and ultrasonic sensors 154 included in the external recognition sensor 125 may have various configurations other than those shown in FIG. 27 . Specifically, the ultrasonic sensors 154 may also sense the sides of the vehicle 101, and the LiDAR 153 may sense the rear of the vehicle 101. The installation positions of the sensors are not limited to the above-described examples. The number of each sensor may be one or more.

[0223] Although the embodiments of the present disclosure have been described above, these embodiments may be implemented with various modifications within the scope of the gist of the present disclosure. For example, two or more embodiments may be implemented in combination.

[0224] The present disclosure may also be configured as follows.

[0225] (1) A photodetector comprising: a substrate including a first semiconductor layer, a second semiconductor layer, and a first multiplication region within an area equivalent to one pixel, wherein the first semiconductor layer has sensitivity to infrared light in a first wavelength band, the second semiconductor layer has sensitivity to infrared light in a second wavelength band different from the first wavelength band, and has a larger absorption coefficient for infrared light in the second wavelength band than the first semiconductor layer, and the first multiplication region multiplies carriers from at least the first semiconductor layer; and a first electrode electrically connected to the first multiplication region.

[0226] (2) The photodetector according to (1), wherein the first semiconductor layer is a Si (silicon) layer, and the second semiconductor layer is a Ge (germanium) layer.

[0227] (3) The photodetector according to (1), wherein the first wavelength band is a near infrared (NIR) wavelength band, and the second wavelength band is a short wavelength infrared (SWIR) wavelength band.

[0228] (4) The photodetector according to (1), wherein the substrate further includes a second multiplication region within the one pixel region that multiplies carriers from at least the second semiconductor layer, and further includes a second electrode electrically connected to the second multiplication region.

[0229] (5) The photodetector according to (4), wherein, when carriers from the first semiconductor layer are detected via the first electrode, carriers from the second semiconductor layer are discharged via the second electrode, and when carriers from the second semiconductor layer are detected via the second electrode, carriers from the first semiconductor layer are discharged via the first electrode.

[0230] (6) The photodetector according to (4), wherein the first multiplication region is provided in the first semiconductor layer, and the second multiplication region is provided in the second semiconductor layer.

[0231] (7) The photodetector according to (4), wherein the first multiplication region and the second multiplication region are provided in the first semiconductor layer.

[0232] (8) The photodetector according to (1), wherein the first multiplication region multiplies carriers from the first semiconductor layer and carriers from the second semiconductor layer.

[0233] (9) The photodetector according to (1), wherein the substrate further includes a diffusion region provided at a position overlapping at least a portion of the boundary between the first semiconductor layer and the second semiconductor layer.

[0234] (10) The photodetector according to (9), wherein the diffusion region is further provided near the boundary between adjacent pixels and near the top surface of the substrate.

[0235] (11) The photodetector according to (9), wherein the substrate further includes a second multiplication region within the one pixel region that multiplies carriers from at least the second semiconductor layer, and the diffusion region is provided to separate the first multiplication region and the second multiplication region.

[0236] (12) The photodetector according to (9), wherein the substrate further includes a second multiplication region within the one pixel region that multiplies carriers from at least the second semiconductor layer, and the diffusion region is provided so as not to separate the first multiplication region and the second multiplication region.

[0237] (13) The photodetector according to (9), further comprising a metal layer provided in the diffusion region via an insulating film.

[0238] (14) The photodetector according to (1), wherein a lower end of the second semiconductor layer is provided at a position higher than a lower surface of the substrate.

[0239] (15) The photodetector according to (1), wherein a lower end of the second semiconductor layer is located on a lower surface of the substrate.

[0240] (16) The photodetector according to (1), wherein the second semiconductor layer is provided laterally of the first semiconductor layer.

[0241] (17) The photodetector according to (1), wherein the second semiconductor layer is provided in a vertical direction of the first semiconductor layer.

[0242] (18) A distance measuring device comprising: an illuminance sensor that detects illuminance; a light-emitting device that emits light to be irradiated onto a subject; a light-receiving device that receives the light reflected by the subject; and a control mechanism that measures a distance to the subject by controlling the light-emitting device and the light-receiving device based on the illuminance, wherein the light-receiving device is a substrate including a first semiconductor layer, a second semiconductor layer, and a first multiplication region within an area equivalent to one pixel, wherein the first semiconductor layer has sensitivity to infrared light in a first wavelength band, the second semiconductor layer has sensitivity to infrared light in a second wavelength band different from the first wavelength band, and has a larger absorption coefficient for infrared light in the second wavelength band than the first semiconductor layer, and the first multiplication region multiplies carriers from at least the first semiconductor layer; and a first electrode electrically connected to the first multiplication region.

[0243] (19) The distance measuring device described in (18), wherein the control mechanism measures the distance by detecting carriers from the first semiconductor layer when the illuminance is a first value, and measures the distance by detecting carriers from the second semiconductor layer when the illuminance is a second value higher than the first value.

[0244] (20) The distance measuring device according to (18), wherein the light receiving device includes a plurality of pixels arranged in a two-dimensional array, and at least one pixel of the plurality of pixels includes the first semiconductor layer, the second semiconductor layer, the first multiplication region, and the first electrode.

[0245] 1: Substrate, 1a: Light receiving region, 1b: Isolation region, 2: Interlayer insulating film, 3: Lens layer, 11: Semiconductor layer, 12: Semiconductor layer, 13: p+ region, 14: n+ region, 15: n+ region, 16: pn junction region, 17: Lateral isolation region, 18: Upper isolation region, 21: Contact plug, 22: Contact plug, 31: Lens, 41: Pixel array, 42: Control unit, 51: Insulating film, 52: Light shielding layer, 53: p+ region, 54: p+ region, 55: p++ region, 56: Insulating film, 57: Light shielding layer, 61: Illuminance sensor, 62: MCU, 63: Light emitting device, 63a: Laser diode, 63b: Laser diode, 64: Photodetector (light receiving device), 64a: Readout circuit, 64b: Row selection circuit, 64c: Filter, 101: Vehicle, 111: Vehicle control system, 121: Vehicle control ECU, 122: Communication unit, 123: Map information storage unit, 124: Position information acquisition unit, 125: External recognition sensor, 126: In-vehicle sensor, 127: Vehicle sensor, 131: Memory unit, 132: Cruise assist / autonomous driving control unit, 133: DMS, 134: HMI, 135: Vehicle control unit, 141: Communication network, 151: Camera, 152: Radar, 153: LiDAR, 154: Ultrasonic sensor, 161: Analysis unit, 162: Action planning unit, 163: Operation control unit, 171: Self-position estimation unit, 172: Sensor fusion unit, 173: Recognition unit, 181: Steering control unit, 182: Brake control unit, 183: Drive control unit, 184: Body system control unit, 185: Light control unit, 186: Horn control unit

Claims

1. A photodetector comprising: a substrate including a first semiconductor layer, a second semiconductor layer, and a first multiplication region within an area equivalent to one pixel, wherein the first semiconductor layer has sensitivity to infrared light in a first wavelength band, the second semiconductor layer has sensitivity to infrared light in a second wavelength band different from the first wavelength band, and has a larger absorption coefficient for infrared light in the second wavelength band than the first semiconductor layer, and the first multiplication region multiplies carriers from at least the first semiconductor layer; and a first electrode electrically connected to the first multiplication region.

2. The photodetector device according to claim 1, wherein the first semiconductor layer is a Si (silicon) layer and the second semiconductor layer is a Ge (germanium) layer.

3. The photodetector device according to claim 1, wherein the first wavelength band is a near infrared (NIR) wavelength band, and the second wavelength band is a short wavelength infrared (SWIR) wavelength band.

4. The photodetector device according to claim 1, wherein the substrate further includes a second multiplication region within the one pixel region that multiplies carriers from at least the second semiconductor layer, and further includes a second electrode electrically connected to the second multiplication region.

5. The photodetector according to claim 4, wherein, when carriers from the first semiconductor layer are detected via the first electrode, carriers from the second semiconductor layer are discharged via the second electrode, and when carriers from the second semiconductor layer are detected via the second electrode, carriers from the first semiconductor layer are discharged via the first electrode.

6. The photodetector device according to claim 4, wherein the first multiplication region is provided in the first semiconductor layer, and the second multiplication region is provided in the second semiconductor layer.

7. The photodetector device according to claim 4, wherein the first multiplication region and the second multiplication region are provided within the first semiconductor layer.

8. The photodetector device according to claim 1, wherein said first multiplication region multiplies carriers from said first semiconductor layer and carriers from said second semiconductor layer.

9. The photodetector device of claim 1, wherein the substrate further includes a diffusion region disposed at a position overlapping at least a portion of the boundary between the first semiconductor layer and the second semiconductor layer.

10. The photodetector device according to claim 9, wherein the diffusion regions are further provided near the boundaries between adjacent pixels and near the top surface of the substrate.

11. The photodetector device according to claim 9, wherein the substrate further includes a second multiplication region within the one pixel region that multiplies carriers from at least the second semiconductor layer, and the diffusion region is provided so as to separate the first multiplication region and the second multiplication region.

12. The photodetector device according to claim 9, wherein the substrate further includes a second multiplication region within the one pixel region that multiplies carriers from at least the second semiconductor layer, and the diffusion region is provided so as not to separate the first multiplication region and the second multiplication region.

13. The photodetector device according to claim 9, further comprising a metal layer provided within the diffusion region via an insulating film.

14. The photodetector according to claim 1, wherein the lower end of said second semiconductor layer is provided at a position higher than the lower surface of said substrate.

15. The photodetector device according to claim 1, wherein the lower end of the second semiconductor layer is located on the lower surface of the substrate.

16. The photodetector device according to claim 1, wherein the second semiconductor layer is disposed laterally of the first semiconductor layer.

17. The photodetector device according to claim 1, wherein the second semiconductor layer is disposed in the vertical direction of the first semiconductor layer.

18. A distance measuring device comprising: an illuminance sensor that detects illuminance; a light-emitting device that emits light to be irradiated onto a subject; a light-receiving device that receives the light reflected by the subject; and a control mechanism that controls the light-emitting device and the light-receiving device based on the illuminance to measure the distance to the subject, wherein the light-receiving device is a substrate including a first semiconductor layer, a second semiconductor layer, and a first multiplication region within an area equivalent to one pixel, wherein the first semiconductor layer has sensitivity to infrared light in a first wavelength band, the second semiconductor layer has sensitivity to infrared light in a second wavelength band different from the first wavelength band, and has a larger absorption coefficient for infrared light in the second wavelength band than the first semiconductor layer, and the first multiplication region multiplies carriers from at least the first semiconductor layer; and a first electrode electrically connected to the first multiplication region.

19. The distance measuring device of claim 18, wherein the control mechanism measures the distance by detecting carriers from the first semiconductor layer when the illuminance is a first value, and measures the distance by detecting carriers from the second semiconductor layer when the illuminance is a second value higher than the first value.

20. The distance measuring device of claim 18, wherein the light receiving device comprises a plurality of pixels arranged in a two-dimensional array, and at least one pixel of the plurality of pixels includes the first semiconductor layer, the second semiconductor layer, the first multiplication region, and the first electrode.

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