Single photon avalanche diode, receiving sensor and laser radar

Abstract

The invention belongs to the technical field of optical devices, and provides a single photon avalanche diode, a receiving sensor and a laser radar, a cathode doped region of a first SPAD unit is electrically connected with a first cathode, a cathode doped region of a second SPAD unit is electrically connected with a second cathode, and an anode doped region of the first SPAD unit and an anode doped region of the second SPAD unit are oppositely arranged. The first cathode is electrically connected with the second cathode, the first absorbing material region and the second absorbing material region are isolated by the 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 up-and-down back-to-back SPAD structure is utilized, the transportation distance of photon-generated carriers is halved under the condition of ensuring that the absorption thickness is not changed, and in addition, the transmission efficiency of the photon-generated carriers is improved. The width of a depletion region can be reduced, so that the loading efficiency of an electric field is higher, and a larger avalanche probability is easier to obtain, thereby solving the contradiction between PDE and Jitter characteristics.

Description

Technical Field

[0001] The present application belongs to the field of optical device technology, and in particular relates to a single-photon avalanche diode, a receiving sensor, and a laser radar. Background Art

[0002] Single-photon avalanche diodes (SPADs) have been widely used in applications such as laser detection and ranging (LiDAR), autonomous driving, fluorescence lifetime imaging, quantum communications, and biomedical imaging due to their high sensitivity to single-photon intensities, high temporal resolution, and strong anti-interference capabilities. Jitter refers to the temporal uncertainty of the pulse signal output by a SPAD device when it detects a photon. This jitter significantly impacts several key LiDAR system metrics, including ranging accuracy, system resolution, probability of detection and false alarm rate, dynamic range and maximum detection range, and multi-target discrimination.

[0003] However, in the improvement of single-photon avalanche diodes, improving the photon detection efficiency (PDE) and improving the timing jitter are incompatible. Summary of the Invention

[0004] In order to solve the above technical problems, the embodiments of the present application provide a single-photon avalanche diode, a receiving sensor and a lidar, which aim to solve the problem that the current single-photon avalanche diode cannot take into account both improving PDE and improving jitter.

[0005] A first aspect of an embodiment of the present application provides a single-photon avalanche diode, comprising: 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 area, the second SPAD unit is wrapped by the second absorption material area, the first absorption material area and the second absorption material area are separated by the P-type doped layer, and the P-type doped layer is electrically connected to the anode; The cathode doping region of the first SPAD unit is electrically connected to the first cathode, the cathode doping region of the second SPAD unit is electrically connected to the second cathode, the anode doping region of the first SPAD unit is arranged opposite to the anode doping region of the second SPAD unit, and the first cathode is electrically connected to the second cathode.

[0006] In some embodiments, the P-type doping layer includes a first P-type doping region, a second P-type doping region, and a third P-type doping region. The first P-type doping region is respectively provided on both sides of the first absorption material region, and the second P-type doping region is respectively provided on both sides of the second absorption material region. The third P-type doping region is provided between the first SPAD unit and the second SPAD unit. The first P-type doping region, the second P-type doping region and the third P-type doping region are electrically connected to the anode, and the potentials of the first P-type doping region, the second P-type doping region and the third P-type doping region are consistent.

[0007] In some embodiments, the first cathode is electrically connected to the second cathode through a metal silicon via structure, wherein the metal silicon via structure is located in the first P-type doping region on both sides of the second SPAD unit and the second P-type doping region on both sides of the first SPAD unit.

[0008] In some embodiments, the single-photon avalanche diode further includes a deep trench isolation structure, which is arranged on both sides of the first SPAD unit and the second SPAD unit, and the metal silicon via structure is arranged on the outside of the deep trench isolation structure.

[0009] In some embodiments, a first quenching resistor is provided between the deep trench isolation structure and the first cathode; and / or A second quenching resistor is provided between the deep trench isolation structure and the second cathode.

[0010] In some embodiments, the first cathode is a ring-shaped conductive structure or a transparent conductive structure; and / or The second cathode is a solid conductive structure.

[0011] 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.

[0012] 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 the first cathode heavily doped region, and the cathode doped region of the second SPAD unit is electrically connected to the second cathode via the second cathode heavily doped region.

[0013] The second aspect of an embodiment of the present application also provides a receiving sensor, which includes a plurality of single-photon avalanche diodes as described in any one of the above items, and the plurality of single-photon avalanche diodes are arranged in an array, the first cathodes of adjacent single-photon avalanche diodes are electrically connected to each other, and the second cathodes of adjacent single-photon avalanche diodes are electrically connected to each other.

[0014] The third aspect of the embodiment of the present application also provides a laser radar, which includes a transmitting sensor and a receiving sensor of the second aspect, 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 the target object based on the echo.

[0015] The beneficial effects of the embodiments of the present application are as follows: by setting the cathode doping region of the first SPAD unit to be electrically connected to the first cathode, the cathode doping region of the second SPAD unit to be electrically connected to the second cathode, the anode doping region of the first SPAD unit and the anode doping region of the second SPAD unit to be arranged opposite to each other, the first cathode is electrically connected to 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 to the anode, so that the first SPAD unit and the second SPAD unit are arranged back to back, and by utilizing the upper and lower back-to-back SPAD structure, the distance of photogenerated carrier transport is halved while ensuring that the absorption thickness remains unchanged, and the width of the depletion region can be reduced, so that the electric field loading efficiency is higher, and it is easier to obtain a larger avalanche probability, thereby resolving the contradiction between PDE and Jitter characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of a single photon avalanche diode provided in an embodiment of the present application. Figure 1 ; Figure 2 This is a schematic diagram of a single photon avalanche diode provided in an embodiment of the present application. Figure 2 ; Figure 3 This is a schematic diagram of a single photon avalanche diode provided in an embodiment of the present application. Figure 3 ; Figure 4 This is a schematic diagram of a single photon avalanche diode provided in an embodiment of the present application. Figure 4 . DETAILED DESCRIPTION

[0017] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0018] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0019] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and 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, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more than two of the features. Throughout the description of this application, "at least two" means one or more than one, unless otherwise specifically defined.

[0021] Single-photon avalanche diodes (SPADs), due to their high sensitivity for detecting photons down to single photons, high temporal resolution, and strong anti-interference capabilities, have been widely used in applications such as laser detection and ranging (Lidar), autonomous driving, fluorescence lifetime imaging, quantum communications, and biomedical imaging. Photon detection efficiency (PDE), dark count rate (DCR), and jitter are three key SPAD technical indicators. Higher PDE improves the SPAD's ability to detect weak light; higher DCR results in greater noise, significantly degrading the device's detection capabilities; and lower jitter increases the accuracy of photon arrival time detection.

[0022] In single-photon avalanche diodes (SPADs), jitter is closely related to the location and transport characteristics of photogenerated carriers. For the PDE, the thickness of the absorber material is a crucial factor: the thicker the absorber material, the longer the optical path of the incident light, the more complete the absorption, and the higher the PDE. However, thicker absorbers increase the distance between the photogenerated carriers and the amplification region. In particular, the photogenerated carriers undergo a highly random diffusion period, which further amplifies the randomness of the time it takes for the photogenerated carriers to reach the avalanche region, resulting in a long jitter tail. Consequently, there is a conflict between improving the PDE and improving jitter.

[0023] In order to solve the contradiction between improving PDE and improving Jitter in a single-photon avalanche diode, the present invention provides a single-photon avalanche diode. Figure 1 As shown, the 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 absorption material area 211 and a second absorption material area 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 absorption material area 211, the second SPAD unit 120 is wrapped by the second absorption material area 221, and the first absorption material area 211 is wrapped by the second absorption material area 221. The absorption material area 211 and the second absorption material area 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 doping area 102 of the first SPAD unit 110 is electrically connected to the first cathode 210, and the cathode doping area 102 of the second SPAD unit 120 is electrically connected to the second cathode 220, the anode doping area 101 of the first SPAD unit 110 is arranged opposite to the anode doping area 101 of the second SPAD unit 120, and the first cathode 210 is electrically connected to the second cathode 220.

[0024] In this embodiment, the first absorption material region 211 and the second absorption material region 221 are both P-type doped, the first absorption material region 211 wraps the first SPAD unit 110, and the second absorption material region 221 wraps the second SPAD unit 120. The P-type doping layer 300 is used to isolate the first absorption material region 211 and the second absorption material region 221, thereby forming the first SPAD unit 110 and the second SPAD unit 120 on both sides of the P-type doping layer 300, respectively. The first cathode 210 and the second cathode 220 are respectively located on the upper surface and the lower surface of the single photon avalanche diode. The first SPAD unit The cathode doping region 102 of the element 110 is electrically connected to the first cathode 210, the cathode doping region 102 of the second SPAD unit 120 is electrically connected to the second cathode 220, the anode doping region 101 of the first SPAD unit 110 is arranged opposite to the anode doping region 101 of the second SPAD unit 120, the first cathode 210 is electrically connected to the second cathode 220, the first absorption material region 211 and the second absorption material region 221 are isolated by the P-type doping layer 300, and the P-type doping 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 through the first SPAD unit 110 and the second SPAD unit 120 in sequence, generating photogenerated carriers in the first SPAD unit 110 and the second SPAD unit 120. Under the action of the electric field, these carriers are transported to the two main junctions in the first SPAD unit 110 and the second SPAD unit 120, respectively, and trigger an avalanche. In terms of the optical path, the first SPAD unit 110 and the second SPAD unit 120 are connected in series and share an incident light path. In terms of the circuit, the first SPAD unit 110 and the second SPAD unit 120 are connected in parallel and share an anode 230. The first cathode 210 is electrically connected to the second cathode 220, and both the first SPAD unit 110 and the second SPAD unit 120 can generate avalanches. By utilizing this back-to-back SPAD structure, compared with a single SPAD of the same thickness, it is possible to ensure that the transport path length of the photogenerated carriers is reduced by half while maintaining the same absorption thickness. In addition, the width of the depletion region can be reduced, making the electric field loading efficiency higher, making it easier to obtain a larger avalanche probability, and reducing the jitter characteristics. Therefore, it is possible to ensure that both the PDE and jitter characteristics are enhanced and improved.

[0025] In some embodiments, the doping concentration of the P-type doping layer 300 is greater than the doping concentrations of the first absorption material region 211 and the second absorption material region 221 .

[0026] In some embodiments, the doping concentration of the first absorption material region 211 is greater than the doping concentration of the anode doping region 101 of the first SPAD unit 110 .

[0027] In some embodiments, the doping concentration of the second absorption material region 221 is greater than the doping concentration of the anode doping region 101 of the second SPAD unit 120 .

[0028] In some embodiments, the P-type doping layer 300 includes a first P-type doping region 310, a second P-type doping region 320, and a third P-type doping region 330. The first P-type doping region 310 is respectively arranged on both sides of the first absorption material region 211, and the second P-type doping region 320 is respectively arranged on both sides of the second absorption material region 221. The third P-type doping region 330 is arranged between the first SPAD unit 110 and the second SPAD unit 120. The first P-type doping region 310, the second P-type doping region 320 and the third P-type doping region 330 are electrically connected to the anode 230, and the potentials of the first P-type doping region 310, the second P-type doping region 320 and the third P-type doping region 330 are consistent.

[0029] 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 surface and the lower surface of the single-photon avalanche diode, thereby forming different-surface electrodes, and the first cathode 210 and the second cathode 220 are electrically connected through a metal silicon via structure 520.

[0030] In some embodiments, see Figure 2 As shown, the first cathode 210 and the second cathode 220 are electrically connected through a metal silicon via structure 520, wherein the metal silicon via structure 520 is located in the first P-type doping region 310 on both sides of the second SPAD unit 120 and the second P-type doping region 320 on both sides of the first SPAD unit 110.

[0031] In this embodiment, the first cathode 210 and the second cathode 220 serve as cathodes for the first and second SPAD units 110 and 120, respectively, which are arranged back-to-back. Since the first cathode 210 and the second cathode 220 are located on either side of the single-photon avalanche diode, they can be electrically connected via a metal silicon through-via structure 520, ensuring that the upper and lower diodes within the device are connected in parallel. When incident light is absorbed, it is absorbed in the upper and lower devices, generating photogenerated carriers. Under the action of the electric field, these carriers are transported to their respective avalanche amplification regions, and ultimately have a probability of triggering an avalanche pulse. Compared to 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 depletion region and high voltage loading efficiency, it is easier to deplete the absorption material 1, resulting in a stronger electric field and reduced carrier transport time. Furthermore, the stronger electric field increases the probability of avalanche generation compared to a single SPAD structure of the same thickness, resulting in better PDE and jitter characteristics.

[0032] In some embodiments, see Figure 2 As shown, the single-photon avalanche diode further 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 via structure 520 is disposed outside the deep trench isolation structure 510 .

[0033] 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 arranged between adjacent single-photon avalanche diodes, which can reduce crosstalk between single-photon avalanche diodes.

[0034] In some embodiments, see Figure 2 As shown, a first quenching resistor 511 is disposed between the deep trench isolation structure 510 and the first cathode 210 .

[0035] In some embodiments, see Figure 2 As shown, a second quenching resistor 512 is disposed between the deep trench isolation structure 510 and the second cathode 220 .

[0036] In this embodiment, the quenching resistor can be a polysilicon resistor. The first cathode 210 and the second cathode 220 are short-circuited 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.

[0037] In some embodiments, combined Figure 3 As shown, the cathodes of the first SPAD unit 110 and the second SPAD unit 120 can also be connected to their corresponding quenching resistors respectively and then electrically connected in parallel outside the chip.

[0038] In this embodiment, combined with Figure 3 As shown, the first SPAD unit 110 and the second SPAD unit 120 are back-to-back, and their respective cathodes are first 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 in parallel with the first SPAD unit 110 and a second common cathode in parallel with the second SPAD unit. The first common cathode and the second common cathode are then connected in parallel through the metal silicon via structure 520 to uniformly load the voltage.

[0039] In some embodiments, the first cathode 210 is a ring-shaped conductive structure or a transparent conductive structure.

[0040] 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 be incident from the top of the device.

[0041] In some embodiments, the second cathode 220 is a solid conductive structure.

[0042] 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, thereby enhancing the light absorption efficiency of the device.

[0043] In some embodiments, as Figure 4 As shown, the first SPAD unit 110 is disposed on a first side of the P-type doped layer 300 , the second SPAD unit 120 is disposed on a second side of the P-type doped layer 300 , and the first cathode 210 and the second cathode 220 are coplanar electrodes.

[0044] In this embodiment, the first cathode 210 and the second cathode 220 are coplanar electrodes, and the incident light is incident from the first cathode 210 at the top and enters the interior of 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, and is absorbed by the absorption material to generate photogenerated carriers. The photogenerated carriers are then transported to their respective amplification regions under the action of the electric field, generating an avalanche. All electrodes (anode 230, first cathode 210 and second cathode 220) are located on the same side of the device, thereby forming coplanar electrodes. There is no need to penetrate the entire structure for parallel connection of the cathodes, and the routing is more convenient, which facilitates the connection of quenching resistors and the formation of an array.

[0045] In some embodiments, the anode doped region 101 of the second SPAD unit 120 is formed on the substrate 600, and a Distributed Bragg Reflector (DBR) 700 is provided on the other side of the substrate 600. The incident light passes through the substrate 600 and reaches the bottom of the substrate 600 (note that the substrate 600 is generally a material with a wider energy band width, that is, it does not absorb signal light), and then is 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.

[0046] 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 epitaxial equipment. The epitaxial material may not be limited to silicon material or germanium material, and the epitaxial material may also be III-V group (such as InGaAs / InP) material.

[0047] In some embodiments, the first SPAD unit 110 and the second SPAD unit 120 include an anode doping region 101 and a cathode doping region 102, and a PN junction is formed between the anode doping region 101 and the cathode doping region 102; the cathode doping region 102 of the first SPAD unit 110 is electrically connected to the first cathode 210 via the first cathode 210 heavily doped region, and the cathode doping region 102 of the second SPAD unit 120 is electrically connected to the second cathode 220 via the second cathode 220 heavily doped region.

[0048] An embodiment of the present application further provides a silicon photomultiplier (SiPM) tube composed of at least two single-photon avalanche diodes connected in parallel and used as a single point.

[0049] An embodiment of the present application also provides a receiving sensor, which includes multiple single-photon avalanche diodes as described above, and the multiple single-photon avalanche diodes are arranged in an array, 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.

[0050] The embodiment of the present application also includes a laser radar, which includes a transmitting sensor and the above-mentioned receiving sensor. The transmitting sensor is used to transmit the 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.

[0051] In this embodiment, the cathode doping region 102 of the first SPAD unit 110 is electrically connected to the first cathode 210, the cathode doping region 102 of the second SPAD unit 120 is electrically connected to the second cathode 220, the anode doping region 101 of the first SPAD unit 110 is arranged opposite to the anode doping region 101 of the second SPAD unit 120, the first cathode 210 is electrically connected to the second cathode 220, the first absorption material region 211 and the second absorption material region 221 are isolated by the P-type doping layer 300, and the P-type doping 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. By utilizing the back-to-back SPAD structure, the distance of photogenerated carrier transport is halved while ensuring that the absorption thickness remains unchanged, and the width of the depletion region can be reduced, so that the electric field loading efficiency is higher and it is easier to obtain a larger avalanche probability, thereby resolving the contradiction between PDE and Jitter characteristics.

[0052] Those skilled in the art will clearly understand that for the sake of convenience and brevity of description, only the division of the above-mentioned functional device areas and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed 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. The functional device areas and modules in the embodiments can be integrated into a single device, or each unit can exist physically separately, or two or more units can be integrated into a single unit.

[0053] In addition, the specific names of the functional device areas and modules are only for the purpose of distinguishing them from each other 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 refer to the corresponding processes in the above method embodiments and will not be repeated here.

[0054] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0055] In addition, each functional device area in each embodiment of the present application may be integrated into one device, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0056] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present 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 area, the second SPAD unit is wrapped by the second absorption material area, the first absorption material area and the second absorption material area are separated by the P-type doped layer, and the P-type doped layer is electrically connected to the anode; The cathode doping region of the first SPAD unit is electrically connected to the first cathode, the cathode doping region of the second SPAD unit is electrically connected to the second cathode, the anode doping region of the first SPAD unit is arranged opposite to the anode doping region of the second SPAD unit, and the first cathode is electrically connected to the second cathode.

2. The single photon avalanche diode according to claim 1, wherein The P-type doping layer includes a first P-type doping region, a second P-type doping region, and a third P-type doping region. The first P-type doping region is respectively arranged on both sides of the first absorption material region, and the second P-type doping region is respectively arranged on both sides of the second absorption material region. The third P-type doping region is arranged between the first SPAD unit and the second SPAD unit. The first P-type doping region, the second P-type doping region and the third P-type doping region are electrically connected to the anode, and the potentials of the first P-type doping region, the second P-type doping region and the third P-type doping region are consistent.

3. The single photon avalanche diode according to claim 2, wherein: The first cathode is electrically connected to the second cathode through a metal silicon via structure, wherein the metal silicon via structure is located in the first P-type doping region on both sides of the second SPAD unit and the second P-type doping region on both sides of the first SPAD unit.

4. The single photon avalanche diode according to claim 3, wherein: The single-photon avalanche diode further includes a deep trench isolation structure, which is arranged on both sides of the first SPAD unit and the second SPAD unit, and the metal silicon via structure is arranged outside the deep trench isolation structure.

5. The single photon avalanche diode according to claim 4, wherein: A first quenching resistor is provided between the deep trench isolation structure and the first cathode; and / or A second quenching resistor is provided between the deep trench isolation structure and the second cathode.

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

7. The single photon avalanche diode according to any one of claims 1 to 5, characterized in that: 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.

8. The single photon avalanche diode according to any one of claims 1 to 5, characterized in that: 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 the first cathode heavily doped region, and the cathode doped region of the second SPAD unit is electrically connected to the second cathode via the second cathode heavily doped region.

9. A receiving sensor, characterized in that: The receiving sensor includes a plurality of single-photon avalanche diodes as described in any one of claims 1-8, wherein the plurality of single-photon avalanche diodes are arranged in an array, the first cathodes of adjacent single-photon avalanche diodes are electrically connected to each other, and the second cathodes of adjacent single-photon avalanche diodes are electrically connected to each other.

10. A laser radar, characterized in that: The laser radar comprises a transmitting sensor and a receiving sensor as claimed in claim 9; The emission sensor is used to emit detection laser; The receiving sensor is used to receive the echo of the detection laser and obtain detection information of the target object according to the echo.

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