SPAD device, SPAD array, receiving sensor and laser radar

Abstract

The invention belongs to the technical field of optical devices, and provides an SPAD device, an SPAD array, a receiving sensor and a laser radar, the SPAD device comprises an SPAD unit and an optical element, the optical element can adjust the intensity of light entering a first area and a second area of the SPAD unit, the intensity of the light entering the first area and the second area of the SPAD unit is set to be unequal, and the intensity of the light entering the first area and the second area of the SPAD unit is adjusted to be equal to the intensity of the light entering the second area of the SPAD unit. The light transmittance of the first area and the light transmittance of the second area are related to the positions of the first area and the second area, so that the photon detection efficiency of each sub-area of the SPAD device can be balanced according to application requirements, and the application scene of the SPAD device is expanded.

Description

Technical Field

[0001] This application belongs to the field of optical device technology, and particularly relates to a SPAD device, SPAD array, receiving sensor and lidar. Background Technology

[0002] SPAD arrays, due to their advantages such as high sensitivity to detect intensities down to single photons, high time resolution, and strong anti-interference capabilities, are widely used in applications such as laser detection and ranging systems (Lidar), autonomous driving, fluorescence lifetime imaging, quantum communication, and biomedical imaging. These SPADs are typically composed of at least two connected in parallel and used as a single point in a silicon photomultiplier tube (SiPM). With advancements in silicon manufacturing technology, SPAD array design using silicon as the absorption and avalanche material has become a hot topic in industry. Furthermore, by utilizing various CMOS manufacturing technologies, SPADs can be easily integrated with different quenching and readout circuits, thus offering significant technological advantages.

[0003] However, in a SPAD array, each SPAD unit is treated as a separate pixel, and the light intensity detected by each pixel can be output separately. The amount of incident light received by SPAD units at different positions in the SPAD array is different, and the amount of incident light in the edge areas is smaller, which may lead to excessive differences in the electrical signals output by the SPAD units when excited. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a SPAD device, a SPAD array, a receiving sensor, and a lidar, aiming to solve the problem that the amount of incident light received by SPAD units at different locations in the SPAD device varies, which may lead to excessive differences in the electrical signals output by the SPAD units upon excitation.

[0005] A first aspect of this application provides a SPAD device, the SPAD device comprising:

[0006] SPAD unit, the SPAD unit comprising at least a first region and a second region;

[0007] An optical element is provided for adjusting the intensity of light incident on a first region and a second region of the SPAD unit, wherein the light intensities in the first region and the second region are unequal.

[0008] In some embodiments, the optical element includes a microlens disposed on the back side of the SPAD unit, the microlens being used to adjust the amount of light converged to a corresponding first region.

[0009] In some embodiments, the height of the microlens is related to the amount of light converged to the corresponding first region; and / or the curvature of the microlens is related to the amount of light converged to the corresponding first region.

[0010] In some embodiments, the optical partition further includes a pad layer disposed between the microlens and the SPAD unit, the height of which is related to the amount of light converged to the corresponding first region.

[0011] In some embodiments, the padding layer is also doped with an absorbing material, the light absorption coefficient of which is negatively correlated with the amount of light converged to the corresponding first region.

[0012] In some embodiments, the proportion of the absorbing material is negatively correlated with the amount of light converged to the corresponding first region.

[0013] In some embodiments, the optical element further includes an aperture structure for adjusting the amount of light converged to the corresponding sub-region.

[0014] In some embodiments, the SPAD device includes a back metal mesh disposed between the microlens and the SPAD unit, the back metal mesh being used to connect the SPAD unit to a corresponding external electrode; the area of ​​the back metal mesh is negatively correlated with the amount of light converged to the corresponding sub-region in the SPAD unit.

[0015] In some embodiments, the SPAD device includes a front metal trace layer for reflecting incident light transmitted through the SPAD unit; the area of ​​the front metal trace layer is positively correlated with the amount of light converged to the sub-region corresponding to the SPAD unit.

[0016] In some embodiments, the optical partition includes a light scattering structure located between the microlens and the SPAD unit, the light scattering structure being used to adjust the optical path of the incident light.

[0017] A second aspect of this application provides a SPAD array comprising at least two SPAD devices as described in any of the above embodiments, wherein the at least two SPAD devices form a SPAD array; the SPAD array comprises at least a third region and a fourth region, wherein the intensity of light incident on the third region and the fourth region is unequal.

[0018] In some embodiments, the density of the SPAD devices in the third region is different from the density of the SPAD devices in the fourth region.

[0019] In some embodiments, the number of SPAD devices in the third region is different from the number of SPAD devices in the fourth region.

[0020] In some embodiments, the fourth region is located outside the third region, and the intensity of light incident on the third region is greater than the intensity of light incident on the fourth region.

[0021] In some embodiments, the distance between the center of the SPAD device and the center of the SPAD array is positively correlated with the amount of light focused onto the SPAD device via the optical element.

[0022] A third aspect of this application provides a receiving sensor that includes a SPAD device as described in any of the above embodiments or a SPAD array as described in any of the above embodiments.

[0023] A fourth aspect of this application provides a lidar, which includes a transmitting sensor and a receiving sensor as described in the above embodiments;

[0024] The emission sensor is used to emit a detection laser;

[0025] The receiving sensor is used to receive the echo of the detection laser and obtain the detection information of the target object based on the echo.

[0026] The beneficial effects of this application's embodiments are as follows: The SPAD device includes a SPAD unit and optical elements. The SPAD unit includes at least a first region and a second region. The optical elements are used to adjust the intensity of light incident on the first and second regions of the SPAD, and the light intensities in the first and second regions are unequal. By adjusting the amount of light entering the corresponding sub-regions of the SPAD unit through the optical elements, the photon detection efficiency of each sub-region of the SPAD device can be balanced according to application requirements, thus expanding the application scenarios of the SPAD device. Attached Figure Description

[0027] Figure 1 This is a top view schematic diagram of the SPAD device provided in the embodiments of this application;

[0028] Figure 2 This is a cross-sectional schematic diagram of the SPAD device provided in the embodiments of this application;

[0029] Figure 3 This is a schematic diagram of the SPAD device provided in the embodiments of this application. Figure 1 ;

[0030] Figure 4 This is a schematic diagram of the SPAD device provided in the embodiments of this application. Figure 2 ;

[0031] Figure 5 This is a schematic diagram of the SPAD device provided in the embodiments of this application. Figure 3 ;

[0032] Figure 6 This is a schematic diagram of the SPAD device provided in the embodiments of this application. Figure 4 ;

[0033] Figure 7 This is a schematic diagram of the SPAD device provided in the embodiments of this application. Figure 5 ;

[0034] Figure 8 This is a schematic diagram of the SPAD device provided in the embodiments of this application. Figure 6 ;

[0035] Figure 9 This is a schematic diagram of the SPAD array provided in the embodiments of this application. Figure 1 ;

[0036] Figure 10 This is a schematic diagram of the SPAD array provided in the embodiments of this application. Figure 2 ;

[0037] Figure 11 This is a schematic diagram of the SPAD unit provided in the embodiments of this application. Detailed Implementation

[0038] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0039] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0040] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0041] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or at least two of that feature. In the description of this application, "at least two" means one or more, unless otherwise explicitly specified.

[0042] Due to their advantages such as high sensitivity to detect single photons with intensities as low as 1, high time resolution, and strong anti-interference capabilities, SPAD arrays, consisting of at least two SPADs connected in parallel as a single-point silicon photomultiplier tube (SiPM), have been widely used in laser detection and ranging systems (Lidar), autonomous driving, fluorescence lifetime imaging, quantum communication, and biomedical imaging. In a SPAD array, the photon detection efficiency (PDE) of each SPAD cell is related to its position. Each SPAD cell acts as an individual pixel, and the light intensity detected by each pixel can be output independently. The amount of incident light received by SPAD cells at different positions in the array varies, with the edge regions receiving less incident light, which may lead to excessive differences in the electrical signals output by the excited SPAD cells.

[0043] To address the aforementioned technical problems, this application provides a SPAD device, see [link to relevant documentation]. Figure 1 and Figure 2 As shown, the SPAD device includes a SPAD unit 110 and an optical element 200. The SPAD unit 110 includes at least a first region and a second region. The optical element 200 is used to adjust the intensity of light incident on the first and second regions of the SPAD unit 110, such that the intensities of the light incident on the first and second regions are unequal. As an example, the first region can be the central region of the SPAD, and the second region can be the edge region of the SPAD. By adjusting the incident light intensity on the first and second regions, the dynamic range of the sensor is extended.

[0044] The dynamic range of the first and second regions of the receiving sensor is related to the reflectivity discrimination of the radar system at close to medium ranges. Specifically, if the first region is the central region of the receiving device and the second region is the edge region, and the radar system's maximum ranging requirement is dist1, then the dynamic range of the first region needs to cover dist1. Furthermore, if the saturation detection distance corresponding to the central region is dist2, then the detection range corresponding to the first region of the receiving device is [dist2, dist1]. Simultaneously, if the design aims to distinguish the closest distance as dist3, then the intensity dynamic range corresponding to the reflectivity to be distinguished, which the second region needs to cover, is [dist3, dist2].

[0045] The dynamic range of the first and second regions of the receiving device is related to the coaxial near-range fronting blind zone of the radar. Specifically, if the dynamic range of the fronting energy is dynamic1 and the intensity dynamic range corresponding to the near-range desired reflectivity is dynamic3, then the detection range required for the second region is [dynamic3, dynamic1+dynamic2].

[0046] As an example, the optical element 200 can be disposed on the back side of the SPAD unit 110. By adjusting the parameters of the optical element 200, the amount of light incident on the SPAD unit 110 via the optical element 200 can be adjusted. The parameters of the optical element 200 include one or more combinations of reflectivity, transmittance, placement height, and radius of curvature. By setting the optical parameters of the optical element 200, the intensity of light incident on a first region or a second region of the SPAD unit 110 can be adjusted so that the intensities of light incident on the first region and the second region are unequal, thereby expanding the dynamic range of the receiving device.

[0047] In some embodiments, the SPAD unit 110 can be divided into multiple sub-regions, and the optical element 200 includes multiple optical partitions 210. Each sub-region of the SPAD corresponds to one optical partition 210, and the parameters of each optical partition 210 are related to its position. The SPAD unit 110 can correspond to one or more optical elements. When the SPAD unit corresponds to one optical element 200, the optical element 200 can have different optical partitions 210, and each optical partition 210 corresponds to different optical parameters. When the SPAD unit has multiple optical elements 200, the optical parameters of each optical element 210 are different. The parameters of each optical partition include the emissivity, transmittance, setting height, and radius of curvature of the optical device corresponding to the optical partition. The optical partitions of the SPAD unit can be set according to the detection accuracy requirements of the SPAD unit. When the detection accuracy requirement of the SPAD unit is a first accuracy, the number of partitions of the SPAD is a first number. When the detection accuracy requirement of the SPAD unit is a second accuracy, the number of partitions of the SPAD is a second number. When the first precision requirement is higher than the second precision requirement, then the first quantity is greater than the second quantity.

[0048] In some embodiments, the SPAD unit 110 may be divided into multiple sub-regions, including at least a first region and a second region, wherein the first region and the second region are each a sub-region of the SPAD unit 110.

[0049] In some embodiments, the transmittance of the corresponding optical partition 210 can be set according to the position of each sub-region. By setting the structure and parameters of each optical partition 210 in the optical element 200, the amount of light entering each sub-region of the SPAD unit 110 can be adjusted, thereby balancing the photon detection efficiency of each sub-region of the SPAD unit 110 according to application requirements, so that the SPAD device can adapt to different application scenarios and expand the application scenarios of the SPAD device.

[0050] In some embodiments, the front or back surface of the SPAD unit 110 may be divided into multiple sub-regions. As an example, the multiple sub-regions include a first region and a second region. The optical element 200 may adjust the intensity of light incident on the first region or the second region of the SPAD unit 110, so that the intensity of light incident on the first region and the second region of the SPAD unit 110 is not equal.

[0051] As an example, the SPAD unit 110 includes multiple sub-regions, and optical partitions 210 can be selectively formed on some sub-regions, while optical partitions 210 may not be set on other sub-regions. Alternatively, different optical partitions can be set on different sub-regions within the multiple sub-regions included in the SPAD unit 110. For example, the parameters of the optical partitions set on different sub-regions may be different. For instance, one type of optical partition 210 may be formed on the back surface area corresponding to one sub-region on the front of the SPAD unit 110, while another type of optical partition 210 may be formed on the back surface area corresponding to another sub-region. Or, no optical partition 210 may be set on the back surface area corresponding to one sub-region. Similarly, one type of optical partition 210 may be formed on some sub-regions on the back of the SPAD unit 110, while another type of optical partition 210 may be set on the front surface area corresponding to other sub-regions.

[0052] As an example, optical partition 210 can be at least one of microlens, pad layer, absorbing material layer, aperture structure, and scattering structure.

[0053] As an example, the absorbing material layer can be formed by doping the absorbing material in the pad layer, and the light absorption coefficient of the absorbing material is negatively correlated with the amount of light converged to the corresponding first region.

[0054] In this embodiment, the padding layer can be formed on the back side of the SPAD unit 110.

[0055] In some embodiments, the transmittance of the optical partition 210 is positively correlated with a first distance, which is the distance between the center of the optical partition 210 and the SPAD unit 110.

[0056] In this embodiment, the SPAD unit 110 can be divided into multiple sub-regions. On the back side of the SPAD unit 110, the sub-regions closer to the center of the SPAD unit 110 may receive more incident light, while the sub-regions farther from the center of the SPAD unit 110 will receive less incident light. By setting the transmittance of the optical partition 210 to be related to the distance between the optical partition 210 and the center of the SPAD unit 110, the transmittance of the optical partition 210 is greater when the distance is larger, and the transmittance of the optical partition 210 is smaller when the distance is smaller. This balances the amount of light incident on each sub-region of the SPAD unit 110, making the amount of light in each sub-region of the SPAD unit 110 similar, reducing the difference in photon detection efficiency among the sub-regions of the SPAD unit 110, and improving the stability of photon detection.

[0057] As an example, see Figure 3As shown, the optical element 200 includes a microlens 211 disposed on the back side of the SPAD unit 110, the microlens 211 being used to adjust the amount of light focused onto the corresponding sub-region.

[0058] In this embodiment, a microlens 211 is formed on the back side of the SPAD unit 110, and the amount of light entering the corresponding SPAD unit 110 can be adjusted by regulating the parameters of the microlens 211. The height of the microlens is related to the amount of light converged to the corresponding first region. It is understood that the influence of the microlens height on the receiving efficiency is mainly reflected in its focusing ability of the incident light. When the height is appropriate, the microlens can effectively focus the light onto the active area of ​​the receiving device, thereby improving the receiving efficiency. When the height of the microlens is too high, it may cause the light to diverge before reaching the receiving surface, thereby reducing the light intensity of the receiving device. Conversely, if the height of the microlens is too low, the light cannot be focused, which will also affect the light intensity reaching the receiving device. Therefore, the amount of light converged to the first region can be adjusted by setting the height of the microlens. The first region is a sub-region of the receiving device.

[0059] Among them, the curvature radius and curvature distribution of the microlens 211 affect the propagation mode of the incident light inside the microlens 211, thereby affecting the equivalent fill factor of the SPAD device. By adjusting the curvature radius and curvature distribution of the microlens 211, the transmittance of the microlens 211 can be indirectly adjusted.

[0060] As an example, the optical element 200 includes a microlens 211 disposed on the back side of the SPAD unit 110, the microlens 211 being used to adjust the amount of light focused onto a corresponding first region or second region.

[0061] As an example, a back metal mesh 212 is formed on the first dielectric layer 310. The back metal mesh 212 serves to lead one of the electrodes of the SPAD unit 110 out from the back side and connects the SPAD unit 110 to the corresponding external electrode. Deep trench isolation pillars 213 can isolate self-excited photons generated by the SPAD unit 110 under incident light excitation, reducing crosstalk of self-excited photons to adjacent SPAD units 110, reducing the leakage of self-excited photons, lowering the probability of photon crosstalk, and reducing the optical crosstalk of the device. A second dielectric layer 320 is disposed between the SPAD unit 110 and the front metal trace layer 214; wherein the front metal trace layer 214 is electrically connected to the corresponding SPAD unit 110 through contact wires 321.

[0062] As an example, the SPAD unit 110 includes a first doped region 111 and a second doped region 112 stacked on the second dielectric layer 320, wherein the first doped region 111 and the second doped region 112 form a PN junction.

[0063] As an example, the first doped region 111 and the second doped region 112 are two doped regions of different polarities. The first doped region 111 and the second doped region 112 form a PN junction. The amplification region is the region with the strongest electric field of the PN junction. The amplification region is mainly used for the generation and amplification of avalanches. The depletion region is the space charge region generated by the device under a certain voltage. Electrons or holes generated in it can enter the amplification region through the downward drift motion of the electric field to generate avalanches.

[0064] As an example, the height of the microlens 211 is related to the amount of light converged to the corresponding sub-region.

[0065] In this embodiment, the height of the microlens 211 can determine the focusing position of the incident light. By adjusting the height of the microlens 211, the focusing position of the incident light can be made near the magnification area, which can improve the PDE of the SPAD unit 110.

[0066] As an example, the height of the microlens 211 is related to the amount of light converged to the corresponding first region.

[0067] As an example, the curvature of the microlens 211 is related to the amount of light converged to the corresponding sub-region.

[0068] In this embodiment, the curvature of the microlens 211 can determine the focal position of the incident light. By adjusting the curvature of the microlens 211 so that the focal position of the incident light is near the magnification area, the PDE of the SPAD unit 110 can be improved.

[0069] As an example, the curvature of the microlens 211 is related to the amount of light converged to the corresponding first region.

[0070] As an example, the type of microlens 211 is related to the amount of light converged to the corresponding first region. For example, the microlens 211 can be a ring-shaped microlens or a spherical microlens. When a first intensity of light needs to be converged to the first region, a ring-shaped microlens can be used; when a second intensity of light needs to be converged to the first region, a spherical microlens can be used. The first intensity is greater than the second intensity.

[0071] As an example, the surface morphology of the microlens 211 is related to the amount of light converged to the corresponding sub-region.

[0072] In this embodiment, the surface morphology of the microlens 211 can determine the transmittance of the incident light. By adjusting the surface morphology of the microlens 211, the amount of incident light incident on the SPAD unit 110 via the microlens 211 can be adjusted. For example, the effect of a lens with a circular bottom on the PDE is worse than that of a lens with a square bottom.

[0073] As an example, the transmittance of the microlens 211 can be adjusted by simultaneously adjusting two or three of the following: the height, curvature, and surface morphology.

[0074] As an example, see Figure 4 As shown, the optical element 200 also includes a padding layer 215 disposed between the microlens 211 and the SPAD unit 110, the height of which is related to the amount of light converged to the corresponding sub-region.

[0075] In this embodiment, the height of the pad height 215 can determine the focusing position of the incident light. The size of the PDE can be adjusted by adjusting the height of the pad height 215. For example, by adjusting the height of the pad height 215 so that the focusing position of the incident light is near the amplification area, the PDE of the SPAD unit 110 can be improved.

[0076] As an example, the height of the pad 215 is related to the amount of light that converges to the corresponding first area.

[0077] As an example, the padding layer 215 is also doped with absorbing material, and the light absorption coefficient of the absorbing material is negatively correlated with the amount of light converged to the corresponding sub-region.

[0078] In this embodiment, the SPAD unit 110 can be divided into multiple sub-regions, and the optical element 200 includes multiple optical partitions 210. The transmittance of each optical partition 210 is related to its position. The thickness of the pad layer 215 in each optical partition 210 and the absorbing material in the pad layer 215 can be determined according to the distance between the optical partition 210 and the center position of the SPAD unit 110. By adjusting the thickness of the pad layer 215 in each optical partition 210 and the absorbing material in the pad layer 215, the amount of light entering each sub-region of the SPAD unit 110 can be adjusted. Thus, the photon detection efficiency of each sub-region of the SPAD device can be balanced according to the application requirements, so that the SPAD device can adapt to different application scenarios and expand the application scenarios of the SPAD device.

[0079] As an example, the light absorption coefficient of the absorbing material is negatively correlated with the amount of light converged to the corresponding first region.

[0080] As an example, the absorbing material can also be coated on the surface of the pad layer 215. Adding the absorbing material to the back of the SPAD unit 110 can adjust the proportion of light entering the absorption region of the SPAD unit 110, thereby changing the PDE of the SPAD unit 110. In specific applications, the absorbing material can be adjusted according to the required wavelength and the required absorption ratio. For example, by adjusting the composition and thickness of the absorbing material in each sub-region, the relative PDE of each sub-region of the SPAD unit 110 can be adjusted within the range of 0%-100%, thereby balancing the photon detection efficiency of each sub-region of the SPAD unit 110 according to application requirements. This allows the SPAD device to adapt to different application scenarios, expanding the application scenarios of the SPAD device.

[0081] As an example, the absorbing material can also be coated on the surface of the first dielectric layer 310. Adding the absorbing material to the back of the SPAD unit 110 can adjust the proportion of light entering the absorption region of the SPAD unit 110, thereby changing the PDE of the SPAD unit 110. In specific applications, the absorbing material can be adjusted according to the required wavelength and the required absorption ratio. For example, by adjusting the composition and thickness of the absorbing material in each sub-region, the relative PDE of each sub-region of the SPAD unit 110 can be adjusted within the range of 0%-100%, thereby balancing the photon detection efficiency of each sub-region of the SPAD unit 110 according to application requirements. This allows the SPAD device to adapt to different application scenarios, expanding the application scenarios of the SPAD device.

[0082] As an example, the proportion of absorbing material is negatively correlated with the amount of light converged to the corresponding sub-region.

[0083] In this embodiment, the higher the proportion of absorbing material within the padding layer 215, the less incident light passes through the padding layer 215. On the front of the SPAD unit 110, sub-regions closer to the center of the SPAD unit 110 may receive more incident light, while sub-regions farther from the center of the SPAD unit 110 will receive less incident light. By setting a higher proportion of absorbing material within the padding layer 215 corresponding to sub-regions closer to the center of the SPAD unit 110, and a lower proportion of absorbing material within the padding layer 215 corresponding to sub-regions farther from the center of the SPAD unit 110, the amount of light incident on each sub-region of the SPAD unit 110 is balanced, making the amount of light in each sub-region of the SPAD unit 110 similar, reducing the photon detection efficiency of each sub-region of the SPAD unit 110, and improving the stability of photon detection.

[0084] As an example, the proportion of absorbing material is negatively correlated with the amount of light converged to the corresponding first region.

[0085] As an example, the optical element 200 also includes an aperture structure for adjusting the amount of light focused onto the corresponding sub-region.

[0086] In this embodiment, by providing an aperture structure on the back side of the SPAD unit 110, the amount of incident light incident on the SPAD unit 110 can be adjusted. Specifically, the parameters of the aperture structure are related to the transmittance of the aperture structure. Setting the parameters of the corresponding aperture structure in each optical partition 210 can adjust the amount of light incident on the corresponding sub-region of the SPAD unit 110 via the aperture structure, thereby adjusting the amount of light converged to each sub-region of the SPAD unit 110, making the amount of light in each sub-region of the SPAD unit 110 similar, reducing the photon detection efficiency of each sub-region of the SPAD unit 110, and improving the stability of photon detection.

[0087] As an example, see Figure 5 As shown, the aperture structure includes a micro-aperture 216, which is disposed on the side of the microlens 211 away from the SPAD unit 110.

[0088] In this embodiment, a micro-aperture 216 is disposed on the back side of the SPAD unit 110, and a microlens 211 is located between the micro-aperture 216 and the SPAD unit 110. By controlling the opening size of the micro-aperture 216, the transmission ratio of incident light can be adjusted, thereby adjusting the PDE of each sub-region of the SPAD unit 110. Incident light is incident on the microlens 211 via the micro-aperture 216. The micro-aperture 216 adjusts the amount of light incident on the microlens 211, and then the microlens 211 adjusts the amount of light converged on each sub-region of the SPAD unit 110, reducing the difference in photon detection efficiency among the sub-regions of the SPAD unit 110 and improving the stability of photon detection.

[0089] As an example, the miniature aperture 216 includes multiple aperture units arranged in an array. The aperture units can be rectangular, trapezoidal, parabolic, inverted pyramid, etc.

[0090] As an example, see Figure 6 As shown, the SPAD device in this embodiment also includes a back metal mesh 212, which is disposed between the microlens 211 and the SPAD unit 110. The back metal mesh 212 is used to connect the SPAD unit 110 and the corresponding external electrode.

[0091] In this embodiment, combined with Figure 6As shown, the aperture structure function can be realized by using the back metal mesh 212 of the SPAD device itself. In specific applications, increasing the width of the back metal mesh 212 can reduce the light-transmitting area on the back of the SPAD unit 110, thereby reducing the PDE of the SPAD unit 110. Conversely, by reducing the width of the back metal mesh 212, the light-transmitting area on the back of the SPAD unit 110 can be increased, thereby increasing the PDE of the SPAD unit 110.

[0092] As an example, the area of ​​the back metal mesh 212 is negatively correlated with the amount of light converged into the corresponding sub-region in the SPAD unit 110.

[0093] In this embodiment, the back metal mesh 212 can be configured as a mesh structure. The larger the area of ​​the back metal mesh 212, the less light is gathered to the sub-region corresponding to the SPAD unit 110. The smaller the area of ​​the back metal mesh 212, the more light is gathered to the sub-region corresponding to the SPAD unit 110.

[0094] As an example, see Figure 7 As shown, the SPAD device in this embodiment includes a front metal trace layer 214, which is used to reflect incident light transmitted through the SPAD unit 110.

[0095] In this embodiment, the front metal trace layer 214 is located on the front of the SPAD unit 110. After the incident light is incident on the back of the SPAD unit 110, part of it is absorbed by the SPAD unit 110, and part of it is emitted through the front of the SPAD unit 110. By using the front metal trace layer 214 of the SPAD device itself as an aperture structure and adjusting the area of ​​the front metal trace layer 214, the reflection effect of the front metal trace layer 214 can be used to adjust the ratio of the amount of light directly transmitted through the front metal trace layer 214 to the amount of light absorbed by the second reflection of the front metal trace layer 214, thereby adjusting the amount of light converged to the corresponding sub-region of the SPAD unit 110.

[0096] As an example, the area of ​​the front metal trace layer 214 is positively correlated with the amount of light converged to the sub-region corresponding to the SPAD unit 110.

[0097] In this embodiment, the front metal trace layer 214 is located on the front side of the SPAD unit 110. After the incident light is incident through the back side of the SPAD unit 110, part of it is absorbed by the SPAD unit 110, and part of it is emitted through the front side of the SPAD unit 110. The area of ​​the front metal trace layer 214 and the amount of light that converges to the corresponding sub-region of the SPAD unit 110.

[0098] As an example, see Figure 8 As shown, the optical element 200 includes a light scattering structure 217, which is located between the microlens 211 and the SPAD unit 110. The light scattering structure 217 is used to adjust the optical path of the incident light.

[0099] In this embodiment, the light scattering structure 217 can change the optical path of the incident light incident on the corresponding sub-region, thereby affecting the absorption ratio of the incident light by the sub-region of the SPAD unit 110, thereby adjusting the amount of light incident on each sub-region of the SPAD unit 110, making the amount of light in each sub-region of the SPAD unit 110 similar, reducing the photon detection efficiency of each sub-region of the SPAD unit 110, and improving the stability of photon detection.

[0100] As an example, such as Figure 8 As shown, when incident light enters the SPAD device, the light scattering structure 217 can change the light path of the incident light through scattering, diffraction and other effects, thereby adjusting the amount of light incident on the sub-region corresponding to the SPAD unit 110 via the light scattering structure 217.

[0101] As an example, the light scattering structure 217 includes multiple light scattering units arranged in an array. The shape of the light scattering units can be rectangular, trapezoidal, parabolic, inverted pyramid, etc.

[0102] As an example, see Figure 8 As shown, the SPAD device also includes a deep trench isolation post 213, which is located on the outside of the SPAD unit 110 and is used to adjust the optical path of the incident light.

[0103] In this embodiment, incident light enters the SPAD device, and part of the incident light can be reflected by the deep trench isolation pillar 213, thereby increasing the optical path of the incident light. By adjusting the distance between the deep trench isolation pillar 213 on the outside of the SPAD unit 110 and the SPAD unit 110, the optical path of the incident light incident on the deep trench isolation pillar 213 can be adjusted, thereby adjusting the amount of light incident on the corresponding sub-region of the SPAD unit 110 via the light scattering structure 217. In this way, the incident light reflected by the deep trench isolation pillar 213 to the sub-region near the edge of the SPAD unit 110 can be adjusted, increasing the amount of incident light in the sub-region near the edge of the SPAD unit 110, making the amount of light in each sub-region of the SPAD unit 110 similar, reducing the difference in photon detection efficiency in each sub-region of the SPAD unit 110, and improving the stability of photon detection.

[0104] In applications using SPAD arrays for ranging, the dynamic range of the received signal from lidar is extremely wide due to the large ranging range and the significant differences in object reflectivity. However, SPAD arrays composed of SPAD devices with high photon detection efficiency (PDE) are prone to saturation when faced with echo energy at medium to close range, making it impossible to distinguish the different reflectivities of objects at medium to close range. Furthermore, preamble saturation can occur in coaxial designs, creating blind spots in short-range ranging.

[0105] To address the issues of SPAD arrays' inability to distinguish between different reflectivities of objects at close to medium range, and the preamble signal saturation and resulting blind spots in close-range ranging caused by coaxial design, this application also provides a SPAD array, see [link to relevant documentation]. Figure 9 As shown, the SPAD array includes at least two SPAD devices as described in any of the above embodiments, and the at least two SPAD devices form a SPAD array. The SPAD array includes at least a third region 103 and a fourth region 104, and the receiving dynamic range of the SPAD array is improved by adjusting the intensity of the light incident on the third region 103 and the fourth region 104 to be unequal.

[0106] In this embodiment, by dividing the SPAD array into at least a third region 103 and a fourth region 104, and by setting the parameters of the SPAD devices in each region, the intensity of the light incident on the third region 103 and the fourth region 104 is made unequal, thereby expanding the receiving dynamic range of the SPAD array.

[0107] As an example, the fourth region 104 is located outside the third region 103, and the intensity of the light incident on the third region 103 is greater than the intensity of the light incident on the fourth region 104.

[0108] In this embodiment, by arranging SPAD devices with higher PDE in the central region of the SPAD array and SPAD devices with lower PDE in the edge region of the SPAD array, a wider dynamic ranging range can be achieved. Specifically, the receiving efficiency of the SPAD devices in the central region can be set to be higher than that in the edge region.

[0109] As an example, see Figure 11 As shown, the SPAD unit 210 includes at least a first region 101 and a second region 102. The first region 101 can be disposed in the peripheral region of the second region 102. By disposing of a corresponding optical element 200 in the first region 101, the amount of light incident on the first region 101 of the SPAD unit 110 via the optical element 200 can be adjusted by adjusting the parameters of the optical element 200.

[0110] As an example, the second region 102 is located in the central region of the SPAD unit 210, and the amount of light incident on the central region is also related to the parameters of the optical element 200. For example, the amount of light incident on the central region is related to the shape and area of ​​the shading area of ​​the optical element 200.

[0111] As an example, such as Figure 10 As shown, the density of the SPAD devices in the third region 103 is different from the density of the SPAD devices in the fourth region 104.

[0112] In this embodiment, by setting the density of SPAD devices in the third region 103 and the density of SPAD devices in the fourth region 104, the receiving dynamic range of the SPAD array can be adjusted. Furthermore, by setting the parameters of the SPAD devices in each region, the basic dynamic range of the SPAD array is determined by the density of the SPAD devices and the PDE in the third region 103, and the extended dynamic range of the SPAD array is determined by the density of the SPAD devices and the PDE in the fourth region 104.

[0113] As an example, the number of SPAD devices in the third region 103 is different from the number of SPAD devices in the fourth region 104.

[0114] In this embodiment, the receiving dynamic range of the SPAD array can be adjusted by setting the number of SPAD devices in the third region 103 and the number of SPAD devices in the fourth region. Furthermore, by setting the parameters of the SPAD devices in each region, the basic dynamic range of the SPAD array is determined by the number of SPAD devices and PDE in the third region 103, and the extended dynamic range of the SPAD array is determined by the number of SPAD devices and PDE in the fourth region 104.

[0115] As an example, the PDE of the SPAD devices in each region of the SPAD array can be adjusted by optical element 200, thereby solving the problem of low reflectivity discrimination of the SPAD array when performing mid-range and short-range ranging.

[0116] In this embodiment, the ranging system includes a SPAD array. A first distance, dist1, is determined based on the system's maximum ranging requirement. This allows us to determine the minimum dynamic range (PDE1*n1) of the central region (e.g., the third region) of the SPAD array, which needs to cover the first distance, dist1. Here, n1 is the number of SPAD devices in the central region, and PDE1 is the photon detection efficiency of the central region. The central region will then saturate at a second distance, dist2. Therefore, the dynamic range of the central region covers the distance interval [dist2, dist1].

[0117] In practical applications, if the design expects the closest distance to be distinguished to be dist3, then the dynamic range of the edge region (e.g., the fourth region) is (PDE2*n2), where n2 is the number of SPAD devices in the edge region and PDE1 is the photon detection efficiency of the edge region. In this way, the intensity dynamic range corresponding to the reflectivity to be distinguished in [dist3, dist2] can be covered by setting the parameters of the SPAD devices in the edge region.

[0118] As an example, the distance between the center of the SPAD device and the SPAD array is positively correlated with the amount of light focused onto the SPAD device via optical element 200.

[0119] In this embodiment, multiple SPAD devices form a SPAD array. The transmittance of each SPAD device is set to be related to the spacing between the SPAD device and the center of the SPAD array. The larger the spacing, the greater the transmittance of the SPAD device; the smaller the spacing, the smaller the transmittance of the SPAD device. This balances the amount of light incident on each SPAD device, making the amount of light on each SPAD device similar, reducing the difference in photon detection efficiency among the SPAD devices, and improving the stability of photon detection.

[0120] In some embodiments, as an example, at least two SPAD devices form a SPAD array, and the distance between the centers of the SPAD devices and the SPAD array is positively correlated with the amount of light focused onto the SPAD devices via optical element 200.

[0121] In this embodiment, on the back side of the SPAD array, SPAD devices closer to the center of the SPAD array may receive more incident light, while SPAD devices farther from the center of the SPAD array will receive less incident light. The transmittance of the SPAD device is related to the distance between the SPAD device and the center of the SPAD array. The larger the distance, the greater the transmittance of the SPAD device; the smaller the distance, the smaller the transmittance of the SPAD device. This balances the amount of light incident on each SPAD device, making the amount of light on each SPAD device similar, reducing the difference in photon detection efficiency among the SPAD devices, and improving the stability of photon detection.

[0122] This application also provides a receiving sensor, which includes a SPAD device as described in any of the above embodiments.

[0123] As an example, the receiving sensor includes a SPAD array as described in any of the above embodiments.

[0124] This application also provides a lidar, which includes a transmitting sensor and a receiving sensor as described in any of the above embodiments; the transmitting sensor is used to transmit a detection laser; the receiving sensor is used to receive the echo of the detection laser and obtain the detection information of the target object based on the echo.

[0125] In this embodiment, the intensity of light incident on the first and second regions of the SPAD unit 110 is adjusted by the optical element 200, so that the intensity of light incident on the first and second regions is not equal. The intensity of light incident on the first and second regions is set to be related to their positions. The amount of light entering the corresponding sub-region of the SPAD unit 110 is adjusted by the optical element 200, so as to balance the photon detection efficiency of each sub-region of the SPAD device according to the application requirements, thereby expanding the ranging range of the lidar and extending the dynamic range of the SPAD device.

[0126] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional device areas and modules is used as an example. In practical applications, the above functions can be assigned to different functional device areas and modules as needed, that is, the internal structure of the device can be divided into different functional device areas or modules to complete all or part of the functions described above. In the embodiments, the functional device areas and modules can be integrated into one device, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0127] Furthermore, the specific names of each functional device area and module are merely for easy differentiation and are not intended to limit the scope of protection of this application. The specific working processes of the units and modules in the above system can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0128] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0129] In addition, the functional device regions in the various embodiments of this application can be integrated into one device, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0130] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A SPAD device, characterized by, The SPAD device comprises: a SPAD unit comprising at least a first region and a second region; an optical element for adjusting the intensity of light incident to the first region and the second region of the SPAD unit, the intensity of light of the first region and the second region being different.

2. The SPAD device of claim 1, wherein, The optical element comprises a microlens arranged on the back surface of the SPAD unit, the microlens being used for adjusting the amount of light converging to the corresponding first region; wherein the height of the microlens is related to the amount of light converging to the corresponding first region; and / or the curvature of the microlens is related to the amount of light converging to the corresponding first region.

3. The SPAD device of claim 2, wherein, The optical element further comprises: a heightening layer arranged between the microlens and the SPAD unit, the height of the heightening layer being related to the amount of light converging to the corresponding first region; wherein the heightening layer is further doped with an absorbing material, the light absorption coefficient of the absorbing material being in a negative correlation with the amount of light converging to the corresponding first region; and / or the proportion of the absorbing material is in a negative correlation with the amount of light converging to the corresponding first region.

4. The SPAD device of any one of claims 2-3, wherein, The optical element further comprises: a light barrier structure for adjusting the amount of light converging to the corresponding sub-region.

5. The SPAD device of claim 2, wherein, The SPAD device comprises a back metal grid arranged between the microlens and the SPAD unit, the back metal grid being used for connecting the SPAD unit and the corresponding external electrode; the area of the back metal grid is in a negative correlation with the amount of light converging to the corresponding sub-region in the SPAD unit.

6. The SPAD device of claim 1, wherein, The SPAD device comprises a front metal wiring layer for reflecting the incident light passing through the SPAD unit; the area of the front metal wiring layer is in a positive correlation with the amount of light converging to the corresponding sub-region of the SPAD unit.

7. The SPAD device of claim 2, wherein, The optical element comprises a light scattering structure between the microlens and the SPAD unit, the light scattering structure being used for adjusting the optical path of the incident light.

8. A SPAD array comprising: The SPAD array comprises: at least two SPAD devices as claimed in any one of claims 1-7, the at least two SPAD devices forming a SPAD array; The SPAD array comprises at least a third region and a fourth region, the intensity of light incident to the third region and the fourth region being different.

9. The SPAD array of claim 8, wherein, The density of the SPAD devices in the third region is different from the density of the SPAD devices in the fourth region.

10. A receiving sensor, characterized by The receiving sensor comprises a SPAD device as claimed in any one of claims 1-7 or a SPAD array as claimed in any one of claims 8-9.

11. A lidar, comprising: The laser radar comprises a transmitting sensor and a receiving sensor as claimed in claim 10; The transmitting sensor is used for transmitting a probe laser; The receiving sensor is used for receiving the echo of the probe laser, and obtaining the detection information of a target object according to the echo.

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