Single photon avalanche diode, receiving sensor and lidar

Abstract

The application belongs to the technical field of optical devices, and provides a single-photon avalanche diode, a receiving sensor and a laser radar, wherein the cathode doping region of a first SPAD unit is electrically connected with a first cathode, the cathode doping region of a second SPAD unit is electrically connected with a second cathode, the anode doping region of the first SPAD unit is oppositely arranged with the anode doping region of the second SPAD unit, the first cathode is electrically connected with the second cathode, the first absorption material region and the second absorption material region are isolated by a P-type doping layer, and the P-type doping layer is electrically connected with the anode, so that the first SPAD unit and the second SPAD unit are arranged back to back, the distance of photo-generated carrier transport is halved under the condition of ensuring the invariable absorption thickness by using the back-to-back SPAD structure, the width of the depletion region can be reduced, the loading efficiency of the electric field is higher, and a larger avalanche probability is more easily obtained, thereby solving the contradiction between PDE and Jitter characteristics.

Description

Technical Field

[0001] This application belongs to the field of optical device technology, and particularly relates to a single-photon avalanche diode, a receiving sensor, and a lidar. Background Technology

[0002] Single-photon avalanche diodes (SPADs) have been widely used in LiDAR systems, autonomous driving, fluorescence lifetime imaging, quantum communication, and biomedical imaging due to their advantages such as high sensitivity to single photons with low intensity, high temporal resolution, and strong anti-interference capabilities. Jitter refers to the time uncertainty of the output pulse signal when a SPAD device detects a photon; that is, there is a certain fluctuation in the time from the detection of each photon to the output signal. This jitter has a significant impact on several key indicators of LiDAR systems, such as ranging accuracy, system resolution, detection probability and false alarm rate, dynamic range and maximum detection distance, and multi-target discrimination capability.

[0003] However, there is a trade-off between improving photon detection efficiency (PDE) and reducing timing jitter in the improvement of single-photon avalanche diodes. Summary of the Invention

[0004] To address the aforementioned technical problems, embodiments of this application provide a single-photon avalanche diode, a receiving sensor, and a lidar, aiming to solve the problem that current single-photon avalanche diodes cannot simultaneously improve PDE and reduce jitter.

[0005] The first aspect of this application provides a single-photon avalanche diode, which includes: a first SPAD unit, a second SPAD unit, a first cathode, a second cathode, an anode, a P-type doped layer, a first absorption material region, and a second absorption material region;

[0006] The first SPAD unit and the second SPAD unit are arranged back to back. The first SPAD unit is wrapped by the first absorbent material region, and the second SPAD unit is wrapped by the second absorbent material region. The first absorbent material region and the second absorbent material region are isolated by the P-type doped layer, and the P-type doped layer is electrically connected to the anode.

[0007] The cathode doped region of the first SPAD unit is electrically connected to the first cathode, the cathode doped region of the second SPAD unit is electrically connected to the second cathode, the anode doped region of the first SPAD unit is disposed opposite to the anode doped region of the second SPAD unit, and the first cathode is electrically connected to the second cathode.

[0008] In some embodiments, the P-type doped layer includes a first P-type doped region, a second P-type doped region, and a third P-type doped region. The first P-type doped region is disposed on both sides of the first absorber material region, and the second P-type doped region is disposed on both sides of the second absorber material region. The third P-type doped region is disposed between the first SPAD unit and the second SPAD unit. The first P-type doped region, the second P-type doped region, and the third P-type doped region are electrically connected to the anode, and the potentials of the first P-type doped region, the second P-type doped region, and the third P-type doped region are the same.

[0009] In some embodiments, the first cathode and the second cathode are electrically connected through a through-silicon via (TSV) structure, wherein the TSV structure is located in the first P-type doped region on both sides of the second SPAD unit and the second P-type doped region on both sides of the first SPAD unit.

[0010] In some embodiments, the single-photon avalanche diode further includes a deep trench isolation structure disposed on both sides of the first SPAD unit and the second SPAD unit, and the metal-silicon via structure disposed on the outside of the deep trench isolation structure.

[0011] In some embodiments, a first quenching resistor is provided between the deep trench isolation structure and the first cathode; and / or

[0012] A second quenching resistor is provided between the deep trench isolation structure and the second cathode.

[0013] In some embodiments, the first cathode is a ring-shaped conductive structure or a transparent conductive structure; and / or

[0014] The second cathode is a solid conductive structure.

[0015] In some embodiments, the first SPAD unit is disposed on a first side of the P-type doped layer, the second SPAD unit is disposed on a second side of the P-type doped layer, and the first cathode and the second cathode are coplanar electrodes.

[0016] In some embodiments, the first SPAD unit and the second SPAD unit include an anode doped region and a cathode doped region, and a PN junction is formed between the anode doped region and the cathode doped region; the cathode doped region of the first SPAD unit is electrically connected to the first cathode via a first heavily doped cathode region, and the cathode doped region of the second SPAD unit is electrically connected to the second cathode via a second heavily doped cathode region.

[0017] A second aspect of this application also provides a receiving sensor, the receiving sensor including a plurality of single-photon avalanche diodes as described in any of the preceding claims, the plurality of single-photon avalanche diodes being arranged in an array, the first cathodes of adjacent single-photon avalanche diodes being electrically connected to each other, and the second cathodes of adjacent single-photon avalanche diodes being electrically connected to each other.

[0018] A third aspect of this application also provides a lidar, which includes a transmitting sensor and a receiving sensor. The transmitting sensor is used to transmit a detection laser, and the receiving sensor is used to receive the echo of the detection laser and obtain detection information of a target object based on the echo.

[0019] The beneficial effects of this application embodiment are as follows: By setting the cathode doped region of the first SPAD unit to be electrically connected to the first cathode, the cathode doped region of the second SPAD unit to be electrically connected to the second cathode, the anode doped region of the first SPAD unit and the anode doped region of the second SPAD unit to be arranged opposite to each other, the first cathode to be electrically connected to the second cathode, the first absorber material region and the second absorber material region to be isolated by a P-type doped layer, and the P-type doped layer to be electrically connected to the anode, the first SPAD unit and the second SPAD unit are arranged back to back. By using the back-to-back SPAD structure, the distance for transporting photogenerated carriers is halved while ensuring that the absorption thickness remains unchanged. In addition, the width of the depletion region can be reduced, resulting in higher electric field loading efficiency and easier acquisition of a larger avalanche probability, thereby resolving the contradiction between PDE and jitter characteristics. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the single-photon avalanche diode provided in the embodiments of this application. Figure 1 ;

[0021] Figure 2 This is a schematic diagram of the single-photon avalanche diode provided in the embodiments of this application. Figure 2 ;

[0022] Figure 3 This is a schematic diagram of the single-photon avalanche diode provided in the embodiments of this application. Figure 3 ;

[0023] Figure 4 This is a schematic diagram of the single-photon avalanche diode provided in the embodiments of this application. Figure 4 . Detailed Implementation

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] Single-photon avalanche diodes (SPADs) have been widely used in laser detection and ranging systems (Lidar), autonomous driving, fluorescence lifetime imaging, quantum communication, and biomedical imaging due to their advantages such as high sensitivity to low-intensity light down to single photons, high time resolution, and strong anti-interference capabilities. A silicon photomultiplier tube (SiPM), consisting of at least two SPADs connected in parallel for single-point use, is also widely used. Photon detection efficiency (PDE), dark count rate (DCR), and jitter are three important technical indicators of SPADs. A higher PDE indicates a stronger ability to detect weak light; a higher DCR introduces more noise, significantly degrading the device's detection capability; and a lower jitter results in higher accuracy in detecting photon arrival time.

[0029] In single-photon avalanche diodes (PDEs), jitter is closely related to the position and transport characteristics of photogenerated carriers. For PDEs, the thickness of the absorbing material is a critical factor; the thicker the absorbing material, the longer the optical path of the incident light, resulting in more complete absorption and a higher PDE. However, when the absorbing material is thicker, the photogenerated carriers are farther away from the amplification region. In particular, the photogenerated carriers also undergo a highly random diffusion process, further amplifying the randomness of the time it takes for photogenerated carriers to reach the avalanche region, causing a long tail of jitter. Therefore, there is a contradiction between improving PDE and improving jitter.

[0030] To resolve the trade-off between improving PDE and reducing jitter in single-photon avalanche diodes, this application provides a single-photon avalanche diode, see [link to relevant documentation]. Figure 1 As shown, a single-photon avalanche diode includes: a first SPAD unit 110, a second SPAD unit 120, a first cathode 210, a second cathode 220, an anode 230, a P-type doped layer 300, a first absorber region 211, and a second absorber region 221; the first SPAD unit 110 and the second SPAD unit 120 are arranged back-to-back, the first SPAD unit 110 is wrapped by the first absorber region 211, and the second SPAD unit 120 is wrapped by the second absorber region 221. The receiving material region 211 and the second absorbing material region 221 are isolated by a P-type doped layer 300, and the P-type doped layer 300 is electrically connected to the anode 230; the cathode doped region 102 of the first SPAD unit 110 is electrically connected to the first cathode 210, the cathode doped region 102 of the second SPAD unit 120 is electrically connected to the second cathode 220, the anode doped region 101 of the first SPAD unit 110 and the anode doped region 101 of the second SPAD unit 120 are arranged opposite to each other, and the first cathode 210 is electrically connected to the second cathode 220.

[0031] In this embodiment, both the first absorbing material region 211 and the second absorbing material region 221 are P-type doped. The first absorbing material region 211 encapsulates the first SPAD unit 110, and the second absorbing material region 221 encapsulates the second SPAD unit 120. The P-type doped layer 300 is used to isolate the first absorbing material region 211 and the second absorbing material region 221, thereby forming the first SPAD unit 110 and the second SPAD unit 120 on both sides of the P-type doped layer 300, respectively. The first cathode 210 and the second cathode 220 are located on the upper and lower surfaces of the single-photon avalanche diode, respectively. The cathode doped region 102 of the first SPAD unit 110 is electrically connected to the first cathode 210, and the cathode doped region 102 of the second SPAD unit 120 is electrically connected to the second cathode 220. The anode doped region 101 of the first SPAD unit 110 and the anode doped region 101 of the second SPAD unit 120 are arranged opposite to each other. The first cathode 210 is electrically connected to the second cathode 220. The first absorber region 211 and the second absorber region 221 are isolated by a P-type doped layer 300, and the P-type doped layer 300 is electrically connected to the anode 230, so that the first SPAD unit 110 and the second SPAD unit 120 are arranged back to back. When incident light enters from the first cathode 210, it passes sequentially through the first SPAD unit 110 and the second SPAD unit 120, generating photogenerated carriers. Under the influence of the electric field, these carriers are transported to the two main junctions within the first SPAD unit 110 and the second SPAD unit 120, triggering avalanches. Optically, the first SPAD unit 110 and the second SPAD unit 120 are connected in series, sharing a single incident light path. Electrically, however, they are connected in parallel, sharing a single anode 230. The first cathode 210 is electrically connected to the second cathode 220. Both the first SPAD unit 110 and the second SPAD unit 120 can generate avalanches. By utilizing this back-to-back SPAD structure, compared to a single SPAD of the same thickness, it is possible to reduce the transport path length of photogenerated carriers by half while maintaining the same absorption thickness. Furthermore, it is possible to reduce the width of the depletion region, resulting in higher electric field loading efficiency, easier attainment of a large avalanche probability, and reduced jitter characteristics. Therefore, it is possible to ensure that both PDE and jitter characteristics are improved and enhanced simultaneously.

[0032] In some embodiments, the doping concentration of the P-type doped layer 300 is greater than the doping concentration of the first absorbing material region 211 and the second absorbing material region 221.

[0033] In some embodiments, the doping concentration of the first absorbing material region 211 is greater than the doping concentration of the anode doped region 101 of the first SPAD unit 110.

[0034] In some embodiments, the doping concentration of the second absorber region 221 is greater than the doping concentration of the anode doped region 101 of the second SPAD unit 120.

[0035] In some embodiments, the P-type doped layer 300 includes a first P-type doped region 310, a second P-type doped region 320, and a third P-type doped region 330. The first P-type doped region 310 is disposed on both sides of the first absorber region 211, and the second P-type doped region 320 is disposed on both sides of the second absorber region 221. The third P-type doped region 330 is disposed between the first SPAD unit 110 and the second SPAD unit 120. The first P-type doped region 310, the second P-type doped region 320, and the third P-type doped region 330 are electrically connected to the anode 230, and the potentials of the first P-type doped region 310, the second P-type doped region 320, and the third P-type doped region 330 are the same.

[0036] In some embodiments, the first SPAD unit 110 and the second SPAD unit 120 are respectively formed on both sides of the P-type doped layer 300, and the first cathode 210 and the second cathode 220 are respectively located on the upper and lower surfaces of the single-photon avalanche diode, thereby forming opposite electrodes. The first cathode 210 and the second cathode 220 are electrically connected through a metal silicon through-hole structure 520.

[0037] In some embodiments, see Figure 2 As shown, the first cathode 210 and the second cathode 220 are electrically connected through a through-silicon via structure 520, wherein the through-silicon via structure 520 is located in the first P-type doped region 310 on both sides of the second SPAD unit 120 and the second P-type doped region 320 on both sides of the first SPAD unit 110.

[0038] In this embodiment, the first cathode 210 and the second cathode 220 serve as the cathodes of the back-to-back first SPAD unit 110 and the second SPAD unit 120, respectively. Since the first cathode 210 and the second cathode 220 are located on both sides of the single-photon avalanche diode, they can be electrically connected through a metal-silicon via structure 520, ensuring that the two diodes inside the device are connected in parallel. When the incident light is absorbed, it is absorbed in both devices, generating photogenerated carriers. Under the action of the electric field, these carriers are transported to their respective avalanche amplification regions and eventually have a chance to trigger an avalanche pulse. Compared with a single SPAD structure of the same thickness, the carrier transport distance of the back-to-back structure is halved. Furthermore, due to the small volume of the depletion region and the high voltage loading efficiency, it is easier to deplete the absorbing material 1, resulting in a stronger electric field and a reduced carrier transport time. In addition, the stronger electric field also increases the probability of avalanche generation compared to a single SPAD structure of the same thickness, thus exhibiting better PDE and jitter characteristics.

[0039] In some embodiments, see Figure 2 As shown, the single-photon avalanche diode also includes a deep trench isolation structure 510, which is disposed on both sides of the first SPAD unit 110 and the second SPAD unit 120, and a metal-silicon through-hole structure 520 is disposed on the outside of the deep trench isolation structure 510.

[0040] In this embodiment, each single-photon avalanche diode includes a first SPAD unit 110 and a second SPAD unit 120 arranged back to back. At least two single-photon avalanche diodes are connected in parallel to form a silicon photomultiplier tube. At least one deep trench isolation structure 510 is provided between adjacent single-photon avalanche diodes to reduce crosstalk between single-photon avalanche diodes.

[0041] In some embodiments, see Figure 2 As shown, a first quenching resistor 511 is provided between the deep trench isolation structure 510 and the first cathode 210.

[0042] In some embodiments, see Figure 2 As shown, a second quenching resistor 512 is provided between the deep trench isolation structure 510 and the second cathode 220.

[0043] In this embodiment, the quenching resistor can be a polysilicon resistor. The first cathode 210 and the second cathode 220 are shorted in parallel through wiring. The quenching resistor is located on the deep trench isolation structure 510, completing the connection of the built-in quenching resistor, so that a quenching resistor can be shared.

[0044] In some embodiments, combined with Figure 3 As shown, the cathodes of the first SPAD unit 110 and the second SPAD unit 120 can also be connected to their respective quenching resistors and then connected in parallel around the chip.

[0045] In this embodiment, combined with Figure 3 As shown, the first SPAD unit 110 and the second SPAD unit 120, which are back to back, each have their own cathodes connected to their own quenching resistors. The cathodes of the first SPAD unit 110 and the second SPAD unit 120 are connected in parallel and led to the periphery of the chip to form a first common cathode connected in parallel with the first SPAD unit 110 and a second common cathode connected in parallel with the second SPAD unit. The first common cathode and the second common cathode are then connected in parallel with the cathodes of the upper and lower arrays through a metal silicon through-hole structure 520 to uniformly apply a voltage.

[0046] In some embodiments, the first cathode 210 is a ring-shaped conductive structure or a transparent conductive structure.

[0047] In this embodiment, by setting the first cathode 210 in the incident light direction as a ring-shaped conductive structure or a transparent conductive structure, the incident light efficiency can be improved, ensuring that the incident light can enter from the top of the device.

[0048] In some embodiments, the second cathode 220 is a solid conductive structure.

[0049] In this embodiment, by setting the second cathode 220 at the bottom of the device as a solid metal conductive structure, it can be used as a metal reflector to enhance the reflection of light inside the device, thereby generating secondary absorption within the device and thus enhancing the light absorption efficiency of the device.

[0050] In some embodiments, such as Figure 4 As shown, the first SPAD unit 110 is disposed on the first side of the P-type doped layer 300, the second SPAD unit 120 is disposed on the second side of the P-type doped layer 300, and the first cathode 210 and the second cathode 220 are coplanar electrodes.

[0051] In this embodiment, the first cathode 210 and the second cathode 220 are coplanar electrodes. The incident light enters from the top of the first cathode 210 and enters the device through the first cathode 210. The incident light passes through the first SPAD unit 110 and the second SPAD unit 120 in series along the optical path. After being absorbed by the absorbing material, photogenerated carriers are generated. The photogenerated carriers are then transported to their respective amplification regions under the action of the electric field, generating avalanches. All electrodes (anode 230, first cathode 210 and second cathode 220) are located on the same side of the device, thus forming coplanar electrodes. There is no need to connect the cathodes in parallel through the entire structure, making the wiring more convenient and facilitating the connection of quenching resistors and the formation of arrays.

[0052] In some embodiments, the anode doped region 101 of the second SPAD unit 120 is formed on the substrate 600, and a Bragg reflector 700 (Distributed Bragg Reflector, DBR) is disposed on the other side of the substrate 600. Incident light passes through the substrate 600 to the bottom of the substrate 600 (note that the substrate 600 is generally a material with a wider band width, i.e., it does not absorb signal light), and is then reflected by the Bragg reflector 700 at the bottom, thereby generating secondary absorption, which is beneficial to improving the light absorption efficiency of the device.

[0053] In some embodiments, the first SPAD unit 110 and the second SPAD unit 120 arranged back to back can control the material growth thickness and impurity doping of each layer through an epitaxial device. The epitaxial material is not limited to silicon or germanium, and can also be a III-V group material (e.g., InGaAs / InP).

[0054] In some embodiments, the first SPAD unit 110 and the second SPAD unit 120 include an anode doped region 101 and a cathode doped region 102, and a PN junction is formed between the anode doped region 101 and the cathode doped region 102; the cathode doped region 102 of the first SPAD unit 110 is electrically connected to the first cathode 210 via the heavily doped region of the first cathode 210, and the cathode doped region 102 of the second SPAD unit 120 is electrically connected to the second cathode 220 via the heavily doped region of the second cathode 220.

[0055] This application also provides a silicon photomultiplier tube (SiPM) used as a single point, consisting of at least two single-photon avalanche diodes connected in parallel.

[0056] This application embodiment also provides a receiving sensor, which includes a plurality of single-photon avalanche diodes as described above. The plurality of single-photon avalanche diodes are arranged in an array, and the first cathodes 210 of adjacent single-photon avalanche diodes are electrically connected to each other, and the second cathodes 220 of adjacent single-photon avalanche diodes are electrically connected to each other.

[0057] This application also includes a lidar, which includes a transmitting sensor and the receiving sensor described above. The transmitting sensor is used to transmit a detection laser, and the receiving sensor is used to receive the echo of the detection laser and obtain the target object based on the echo.

[0058] In this embodiment, the cathode doped region 102 of the first SPAD unit 110 is electrically connected to the first cathode 210, and the cathode doped region 102 of the second SPAD unit 120 is electrically connected to the second cathode 220. The anode doped region 101 of the first SPAD unit 110 and the anode doped region 101 of the second SPAD unit 120 are arranged opposite to each other. The first cathode 210 is electrically connected to the second cathode 220. The first absorber region 211 and the second absorber region 221 are isolated by a P-type doped layer 300, and the P-type doped layer 300 is electrically connected to the anode 230. This allows the first SPAD unit 110 and the second SPAD unit 120 to be arranged back-to-back. By using the back-to-back SPAD structure, the distance for transporting photogenerated carriers is halved while maintaining the same absorption thickness. Furthermore, the width of the depletion region can be reduced, resulting in higher electric field loading efficiency and making it easier to obtain a larger avalanche probability, thereby resolving the contradiction between PDE and jitter characteristics.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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 single photon avalanche diode, characterized in that, The single photon avalanche diode comprises a first SPAD unit, a second SPAD unit, a first cathode, a second cathode, an anode, a P-type doped layer, a first absorption material region, and a second absorption material region. The first SPAD unit and the second SPAD unit are arranged back to back, the first SPAD unit is wrapped by the first absorption material region, the second SPAD unit is wrapped by the second absorption material region, the first absorption material region and the second absorption material region are isolated by the P-type doped layer, and the P-type doped layer is electrically connected with the anode. The cathode doped region of the first SPAD unit is electrically connected with the first cathode, the cathode doped region of the second SPAD unit is electrically connected with the second cathode, the anode doped region of the first SPAD unit is arranged opposite to the anode doped region of the second SPAD unit, and the first cathode is electrically connected with the second cathode; the P-type doped layer comprises a first P-type doped region, a second P-type doped region, and a third P-type doped region, the first P-type doped region is arranged on both sides of the first absorption material region, the second P-type doped region is arranged on both sides of the second absorption material region, and the third P-type doped region is arranged between the first SPAD unit and the second SPAD unit, the first P-type doped region, the second P-type doped region, and the third P-type doped region are electrically connected with the anode, and the first P-type doped region, the second P-type doped region, and the third P-type doped region have the same potential; the first SPAD unit and the second SPAD unit are connected in series and share one incident light path.

2. The single photon avalanche diode of claim 1, wherein, The first cathode and the second cathode are electrically connected by a metal silicon through hole structure, wherein the metal silicon through hole structure is located in the first P-type doped region on both sides of the second SPAD unit and the second P-type doped region on both sides of the first SPAD unit.

3. The single photon avalanche diode of claim 2, wherein, The single photon avalanche diode further comprises a deep trench isolation structure, the deep trench isolation structure is arranged on both sides of the first SPAD unit and the second SPAD unit, and the metal silicon through hole structure is arranged outside the deep trench isolation structure.

4. The single photon avalanche diode of claim 3, wherein, A first quenching resistor is arranged between the deep trench isolation structure and the first cathode; and / or A second quenching resistor is arranged between the deep trench isolation structure and the second cathode.

5. The single photon avalanche diode according to any one of claims 1 to 4, wherein The first cathode is a ring-shaped conductive structure or a transparent conductive structure; and / or The second cathode is a solid conductive structure.

6. The single photon avalanche diode according to any one of claims 1 to 4, wherein the semiconductor layer is a p-type semiconductor layer. The first SPAD unit is arranged on a first side of the P-type doped layer, the second SPAD unit is arranged on a second side of the P-type doped layer, and the first cathode and the second cathode are coplanar electrodes.

7. The single photon avalanche diode according to any one of claims 1 to 4, wherein The first SPAD unit and the second SPAD unit comprise anode doped regions and cathode doped regions, and a PN junction is formed between the anode doped regions and the cathode doped regions; the cathode doped region of the first SPAD unit is electrically connected with the first cathode through a first cathode heavily doped region, and the cathode doped region of the second SPAD unit is electrically connected with the second cathode through a second cathode heavily doped region.

8. A receiving sensor, characterized by The receiving sensor comprises a plurality of single photon avalanche diodes as claimed in any one of claims 1-7, the plurality of single photon avalanche diodes being arranged in an array, first cathodes of adjacent single photon avalanche diodes being electrically connected to each other, second cathodes of adjacent single photon avalanche diodes being electrically connected to each other.

9. A lidar, comprising: The laser radar comprises a transmitting sensor and a receiving sensor as claimed in claim 8; The transmitting sensor is configured to transmit a probe laser; The receiving sensor is configured to receive a return wave of the probe laser, and obtain detection information of a target object based on the return wave.

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