Receiving unit, receiving sensor and laser radar

Abstract

The application belongs to the technical field of optical devices, and provides a receiving unit, a receiving sensor and a laser radar. The receiving unit comprises a first SPAD unit and a second SPAD unit. The first SPAD unit has a higher photon detection efficiency and time jitter. An epitaxial isolation layer is arranged in the second SPAD unit to divide an epitaxial layer thereof into a design dead zone and an epitaxial absorption zone. The epitaxial absorption zone covers an avalanche main junction. The design dead zone is located on the epitaxial isolation layer. The thickness of the design dead zone is adjusted through the epitaxial isolation layer, and the thickness of the epitaxial absorption zone can be freely adjusted, so that the receiving unit can meet the device requirements of multiple lower photon detection efficiencies and smaller time jitters. In this way, the SPAD device with multiple photon detection efficiencies and time jitter levels can be simultaneously realized, and the simultaneous optimization of the near distance ranging accuracy and the long distance ranging ability in the radar module application can be met.

Description

Technical Field

[0001] This application belongs to the field of optical device technology, and in particular relates to a receiving unit, a receiving sensor and a lidar. Background Technology

[0002] A single-photon avalanche diode (SPAD) is a special PN junction sensor operating in Geiger mode, capable of absorbing, converting, and outputting electrical pulse signals at light intensities down to the single-photon level, exhibiting extremely high detection sensitivity. Due to their advantages such as high sensitivity to single-photon intensities, 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 applied in scenarios such as laser detection and ranging systems (Lidar), autonomous driving, fluorescence lifetime imaging, quantum communication, and biomedical imaging.

[0003] However, in existing medium- and long-range radar applications, there is a contradiction between short-range testing accuracy and long-range measurement capability. Summary of the Invention

[0004] To address the aforementioned technical problems, embodiments of this application provide a receiving unit, a receiving sensor, and a lidar, aiming to solve the problem that current receiving units cannot simultaneously achieve both short-range testing accuracy and long-range measurement capability.

[0005] A first aspect of this application provides a receiving unit, which includes at least: a first SPAD unit and a second SPAD unit;

[0006] The first SPAD unit and the second SPAD unit include: an N-type heavily doped region, a cathode electrode, an anode electrode, a P-type well region, an N-type well region, a P-type hole conducting region, a P-type heavily doped region, and an epitaxial layer. The P-type well region and the N-type well region form an avalanche main junction. The epitaxial layer covers the avalanche main junction. The P-type hole conducting region covers the epitaxial layer. The N-type well region is connected to the cathode electrode through the N-type heavily doped region. The P-type hole conducting region is connected to the anode electrode through the P-type heavily doped region.

[0007] The second SPAD unit further includes an epitaxial isolation layer, which is used to divide the epitaxial layer into a design dead zone and an epitaxial absorption zone. The epitaxial absorption zone covers the avalanche master junction, and the design dead zone is located on the epitaxial isolation layer.

[0008] In some embodiments, the receiving unit further includes:

[0009] An anode metal trace layer is provided, through which the anode electrodes of adjacent SAPD cells are interconnected.

[0010] In some embodiments, the receiving unit further includes:

[0011] Multiple microlenses are used to focus incident light onto corresponding SPAD units.

[0012] In some embodiments, the receiving unit further includes:

[0013] Deep trench isolation columns, disposed between adjacent SPAD units, are used to isolate adjacent SPAD units; and / or

[0014] The back metal mesh is used to connect the SPAD unit to the corresponding external electrode.

[0015] In some embodiments, the receiving unit includes a plurality of SPAD units, which are arranged in an M-row SPAD unit and an N-column SPAD unit configuration.

[0016] The plurality of SPAD units include the first SPAD unit and the second SPAD unit.

[0017] In some embodiments, the first SPAD unit and the second SPAD unit are spaced apart.

[0018] In some embodiments, the receiving unit includes a first detection area and a second detection area, the first detection area includes a plurality of first SPAD units, the second detection area includes a plurality of second SPAD units, and the first detection area and the second detection area are arranged adjacent to each other.

[0019] In some embodiments, the receiving unit includes a plurality of first detection areas and a plurality of second detection areas, wherein the first detection areas and the second detection areas are spaced apart.

[0020] A second aspect of this application also provides a receiving sensor, which includes a plurality of receiving units as provided in the first aspect, and the plurality of receiving units form a receiving array.

[0021] 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.

[0022] The beneficial effects of the embodiments of this application are as follows: The receiving unit includes a first SPAD unit and a second SPAD unit. The first SPAD unit has high photon detection efficiency and low timing jitter. By setting an epitaxial isolation layer in the second SPAD unit, its epitaxial layer is divided into a design dead zone and an epitaxial absorption region. The epitaxial absorption region covers the avalanche main junction, and the design dead zone is located on the epitaxial isolation layer. By adjusting the thickness of the design dead zone through the epitaxial isolation layer, the thickness of the epitaxial absorption region can be freely adjusted. This allows the receiving unit to meet the device requirements of various lower photon detection efficiencies and lower timing jitter. In this way, SPAD devices with various photon detection efficiencies and timing jitter levels can be realized simultaneously, meeting the synchronous optimization of short-range ranging accuracy and long-range ranging capability in radar module applications. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the receiving unit provided in the embodiments of this application. Figure 1 ;

[0024] Figure 2 This is a schematic diagram of the receiving unit provided in the embodiments of this application. Figure 2 ;

[0025] Figures 3a-3c This is a schematic diagram of a process flow for a receiving unit provided in an embodiment of this application;

[0026] Figures 4a-4d This is a schematic diagram of a process flow for a receiving unit provided in an embodiment of this application;

[0027] Figure 5 This is a horizontal schematic diagram of a portion of the receiving unit provided in an embodiment of this application;

[0028] Figure 6 This is a horizontal schematic diagram of a portion of the receiving unit provided in an embodiment of this application;

[0029] Figures 7a-7d This is a horizontal schematic diagram of a portion of the receiving unit provided in an embodiment of this application;

[0030] Figures 8a-8e This is a horizontal schematic diagram of a portion of the receiving sensor provided in an embodiment of this application. Detailed Implementation

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] Single-photon avalanche diode arrays (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 detection capability for intensities down to single photons, high time resolution, and strong anti-interference capability. 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.

[0036] In medium-to-long-range DTOF lidar applications, the maximum detection distance is generally over 150m, requiring strong pulsed laser power paired with SPAD devices with large PDEs to meet the ranging requirements. Since laser echo intensity is inversely correlated with the square of the distance, for close-range object measurements, the laser intensity is high, especially for close-range highly reflective objects, where the echo intensity is even greater. This relatively reduces the requirements for SPAD PDEs; in fact, close-range highly reflective echoes can even inject a large number of photogenerated carriers into the device's dead zone, resulting in numerous delayed pulses and affecting the resolution and measurement of nearby objects. Furthermore, close-range applications often demand higher ranging accuracy, requiring SPADs with lower timing jitter to reduce accuracy errors. Conversely, for longer-range detection, the laser echo signal is relatively weak. Detecting weak echo signals requires devices with higher PDEs. Meanwhile, for long-range applications, the accuracy requirements for testing can be appropriately reduced, and the requirements for SPAD jitter can be relatively relaxed.

[0037] To resolve the contradiction between short-range testing accuracy and long-range measurement capability in medium- and long-range radar applications, this application provides a receiving unit, see [link to relevant documentation]. Figure 1 As shown, the receiving unit in this embodiment includes: a first SPAD unit 110 and a second SPAD unit 120; the first SPAD unit 110 and the second SPAD unit 120 include: an N-type heavily doped region 104, a cathode electrode 511, an anode electrode 521, a P-type well region 101, an N-type well region 102, a P-type hole conducting region 600, a P-type heavily doped region 103, and an epitaxial layer 200. The P-type well region 101 and the N-type well region 102 form an avalanche main junction, and the epitaxial layer 200 covers the avalanche main junction. The P-type hole conducting region 600 covers the epitaxial layer 200, the N-type well region 102 is connected to the cathode electrode 511 via the N-type heavily doped region 104, and the P-type hole conducting region 600 is connected to the anode electrode 521 via the P-type heavily doped region 103; wherein, the second SPAD unit 120 further includes an epitaxial isolation layer 610, which is used to divide the epitaxial layer 200 into a design dead region 220 and an epitaxial absorption region 210. The epitaxial absorption region 210 covers the avalanche main junction, and the design dead region 220 is located on the epitaxial isolation layer 610.

[0038] In this embodiment, the P-type well region 101 and the N-type well region 102 are two doped regions of different polarities, forming a PN junction. The first SPAD unit 110 fully utilizes the relatively thick epitaxial layer 200 as an epitaxial absorption layer, exhibiting a high PDE, resulting in relatively large jitter. The first SPAD unit 110 can handle distance measurement capabilities where ranging accuracy requirements are relatively low. The second SPAD unit 120, by increasing the epitaxial isolation layer 610 and adjusting the thickness of the dead region 220, can reduce the light absorption volume of the effective working area (epitaxy absorption region 210). Simultaneously, designing the dead region 220 as an effective light absorption attenuation layer can further reduce the light intensity incident on the effective working area of ​​the device's photoelectric conversion, reducing the number of photogenerated carriers in the non-depletion region caused by instantaneous strong light, and significantly reducing the probability of delayed pulses. The thinner photoelectric conversion region thickness significantly reduces the transport path of photogenerated carriers in the effective working area, significantly improving the jitter characteristics of the SPAD in response to incident light. By freely adjusting the thickness of the epitaxial absorption region 210, which plays a decisive role in photoelectric conversion, through the epitaxial isolation layer 610 within the second SPAD unit 120, various device requirements with lower PDE and smaller Jitter can be achieved. In this way, the receiving unit can simultaneously realize SPAD devices with various PDE and Jitter levels. Combined with the 2-transmit 2-receive or multiple-transmit multiple-receive strategy for short-range and medium-to-long-range transmission in radar module applications, the simultaneous optimization of short-range ranging accuracy and long-range ranging capability can be achieved.

[0039] In some embodiments, a P-type well region 101 is formed on an N-type well region 102 to form a SPAD cell with an N-on-P device structure, and the avalanche main junction is composed of a P-type well region 101 and an N-type well region 102.

[0040] In some embodiments, the doping concentration of the N-type well region 102 is greater than the doping concentration of the P-type well region 101, wherein the doping concentration of the P-type well region 101 is 5E16-5E17 cm⁻¹. -3 The doping concentration of the N-type well region 102 is 5E17-5E18. By adjusting the doping of the main junction, a breakdown voltage in the range of 20-30V can be achieved, which is used for SPAD units in the infrared band.

[0041] In some embodiments, the junction depth between the P-type well region 101 and the N-type well region 102 is between 0.5 and 1.5 μm.

[0042] In some embodiments, the cathode electrode 511 is led out to the cathode metal trace layer 510 via the N-type heavily doped region 104 in the N-type well region 102 and the metal electrode.

[0043] In some embodiments, the anode electrode 521 is led out to the anode metal trace layer 520 via the P-type heavily doped region 103 in the P-type hole conductive region 600 and the metal electrode.

[0044] In some embodiments, the P-type hole-conducting region 600 is moderately P-type doped (its doping concentration can range from E16 to E18 cm-3), and has three main functions: 1) to provide an equipotential potential surrounding the main absorption region of the SPAD cell, assisting in the formation of the electric field in the depletion region; 2) to collect holes and provide a low-resistance hole conduction loop; 3) to pin interface defects caused by the physical isolation (DTI) structure process between SPAD cells, thereby reducing DCR.

[0045] In some embodiments, the epitaxial absorption region 210 is a lightly p-doped type (its doping concentration can be in the range of E14-E15 cm⁻¹). -3 This is beneficial for achieving maximum depletion of the main absorption region under breakdown voltage and a certain degree of overbias, thereby maximizing charge collection efficiency.

[0046] In some embodiments, see Figure 2 As shown, the receiving unit also includes an anode metal trace layer 520, through which the anode electrodes 521 of adjacent SAPD units are interconnected.

[0047] In some embodiments, see Figure 2 As shown, the receiving unit also includes a plurality of microlenses 430, which are used to focus the incident light onto the corresponding SPAD unit.

[0048] In this embodiment, at least two SPAD units form a SPAD array, and each SPAD unit is provided with a corresponding microlens 430. The microlens 430 is used to focus the incident light onto the corresponding SPAD unit.

[0049] In some embodiments, see Figure 2 As shown, the receiving unit also includes a deep trench isolation post 410, which is disposed between adjacent SPAD units to isolate adjacent SPAD units.

[0050] In this embodiment, by setting deep trench isolation pillars 410 between adjacent SPAD units, the deep trench isolation pillars 410 can electrically isolate adjacent SPAD units. Self-excited photons generated by the SPAD units when excited by incident light can be reflected when they hit the deep trench isolation pillars 410, which increases absorption and also prevents self-excited photons from interfering with adjacent SPAD units, thereby reducing the leakage of self-excited photons, reducing the probability of photon crosstalk, and reducing the optical crosstalk of the device.

[0051] In some embodiments, the deep trench isolation post 410 can be made of tungsten metal, and a dielectric material is filled around the deep trench isolation post 410. The presence of the deep trench isolation post 410 will reflect crosstalk photons, greatly reducing the probability of optical crosstalk.

[0052] In some embodiments, see Figure 2 As shown, the receiving unit also includes a rear metal mesh 420, which is used to connect the SPAD unit to the corresponding external electrode.

[0053] In some embodiments, the vertical cross-section of the back metal mesh 420 is an inverted trapezoid.

[0054] In some embodiments, the vertical cross-section of the back metal mesh 420 is a multi-layer stepped structure, and the width of each step in the multi-layer stepped structure gradually increases.

[0055] In some embodiments, the vertical cross-section of the back metal mesh 420 is an arc-shaped structure, used to reflect photons illuminating its surface to the SPAD unit.

[0056] In one embodiment, the vertical cross-section of the back metal mesh 420 is an inverted trapezoid.

[0057] In this embodiment, because the back metal mesh 420 has a trapezoidal shape, photons reflected by the sidewalls of the back metal mesh 420 have a high probability of entering other SPAD units. Furthermore, this crosstalk may propagate to distant locations due to the low reflection rate of the lens, causing crosstalk to remote devices and further exacerbating the avalanche chain reaction of crosstalk. Figure 2 As shown, in this embodiment, an inverted trapezoidal back metal mesh 420 is used. At this time, the interface of the back metal mesh 420 tilted inward will reflect the light incident on it back into its own device, reducing photon leakage and reducing the probability of crosstalk of self-excited photons.

[0058] In one embodiment, the vertical cross-section of the back metal mesh 420 is a multi-layer stepped structure, in which the width of each step gradually increases.

[0059] In this embodiment, the vertical cross-section of the back metal mesh 420 is a multi-layer stepped structure, and the width of the multi-layer stepped structure increases step by step, causing the back metal mesh 420 to tilt inward, reflecting the light incident on it back into its own device, reducing photon leakage and lowering the probability of crosstalk of self-excited photons.

[0060] In one embodiment, the width of the multi-tiered stepped structure increases progressively, and the width of the multi-tiered stepped structure is set as an arithmetic sequence.

[0061] In one embodiment, the vertical cross-section of the back metal mesh 420 is an arc-shaped structure used to reflect photons illuminating its surface to the SPAD unit.

[0062] In this embodiment, by setting the vertical cross-section of the back metal mesh 420 to an arc-shaped structure, the interface between the back metal mesh 420 and the microlens 430 can form a total internal reflection interface tilted inward to the SPAD unit, reflecting the photons illuminating its surface to the SPAD unit (i.e., the area of ​​the SPAD unit itself), reducing the overflow of self-excited photons and lowering the crosstalk probability of self-excited photons.

[0063] In some embodiments, in array-packaged photodetector devices, trench structures can be etched into the package structure to reduce crosstalk between device units.

[0064] In one embodiment, the back metal mesh 420 is made of aluminum.

[0065] In some embodiments, multiple layers of metal traces may be formed in the cathode metal trace layer 510 and the anode metal trace layer 520 to lead out another electrode of the SPAD unit to the front electrode, and to output corresponding electrical signals through the front metal trace layer.

[0066] In some embodiments, an N-type well region 102 is formed on a P-type well region 101 to form a SPAD cell of an N-on-P device structure. Compared to the N-on-P device structure, the polarity of each doped region in the P-on-N structure is reversed, and the doping needs to be adjusted and optimized.

[0067] In some embodiments, such as Figures 3a-3c As shown, this can be achieved through ion implantation in the front-end process, combined with... Figure 3a As shown, under the cover of mask 711, the region of epitaxial isolation layer 610 is defined. Epitaxial isolation layer 610 is formed by ion implantation, and under the cover of mask 712, P-type hole conductive region 600 is formed by ion implantation. Figure 3b As shown, ion implantation is continued using a multilayer mask 713 to form a P-type well region 101, an N-type well region 102, an N-type heavily doped region 104, and a P-type heavily doped region 103, as shown. Figure 3cAs shown. After ion implantation, rapid annealing (RTA) is performed for activation. The implantation depth of the epitaxial isolation layer 610 is optimized according to the target PDE and jitter requirements. It should be noted that deeper implanted well layers require thicker photoresist (PR) or hard dielectric masks. This example only shows two different PDE and jitter requirements. In reality, by adding different mask layouts 711, it is possible to simultaneously expand to device designs with progressively decreasing PDE and jitter levels. No changes are required to the passivation, metal interconnect, and BSI stages following the front-end processes.

[0068] In some embodiments, such as Figures 4a-4d As shown, the depth of different Well isolation layers can also be controlled through epitaxy, implantation, and multiple epitaxy methods. First, a mask 721 is placed over a thinner epitaxial layer 200 to perform shallow implantation of the epitaxial isolation layer 610, such as... Figure 4a As shown. Then, the P-type hole conductive region 600 is injected, as follows. Figure 4b As shown. After resist removal and cleaning, an epitaxial thin film is grown to increase the effective absorption region of high PDE devices, such as... Figure 4c As shown, the height of the hole-conducting region is then increased to the surface using photolithography and ion implantation, as... Figure 4d As shown. Subsequent ion implantation can be referenced. Figure 3c This involves some of the process steps. In this embodiment, the multi-step epitaxy method can avoid the machine requirements of deep injection for high-energy injection.

[0069] In some embodiments, the receiving unit includes a plurality of SPAD units, which are arranged in an M-row SPAD unit and an N-column SPAD unit configuration; the plurality of SPAD units include a first SPAD unit 110 and a second SPAD unit 120.

[0070] In this embodiment, in practical applications of SPAD, to improve the dynamic range of light intensity detection, combined with the optical design of the radar module, each receiving unit can be used as a macropixel, for example, such as... Figure 5 As shown, MxN SPAD units are combined to form a macropixel as a detection region. 3x3 first SPAD units 110 can form a detection region array as a macropixel, as shown below. Figure 6 As shown, 3x3 second SPAD units 120 can form a detection region array as a macropixel. In this layout, a small number of macropixel SPADs will result in limited dynamic range, while a large number of SPAD units will result in a decrease in point cloud resolution. Figure 7a , Figure 7b as well as Figure 7cAs shown, a macro-pixel composed of 3x3 SPAD units can simultaneously include a first SPAD unit 110 and a second SPAD unit 120. It can simultaneously detect distant weak light (signal output from a high PDE SPAD) and near-field highly reflective strong light (signal output from a low PDE and Low Jitter SPAD) in any local area, avoiding the loss of near-field highly reflective information due to local scene overexposure. In practical use, the output signal strength and relative relationship of the first SPAD unit 110 and the second SPAD unit 120 can be used to fuse the data of adjacent SPADs through an interpolation algorithm. This allows for the simultaneous detection of distant weak echo signals and near-field highly reflective object echo signals, while ensuring the ranging accuracy of near-field objects.

[0071] In some embodiments, the first SPAD unit 110 fully utilizes the thicker epitaxial layer 200 as an epitaxial absorption layer, resulting in a higher PDE and thus a relatively larger Jitter. The first SPAD unit 110 can handle distance measurement capabilities where ranging accuracy requirements are relatively low. The second SPAD unit 120 has a lower PDE and less Jitter. Depending on application requirements, the number of first SPAD units 110 within each macropixel and / or the number of second SPAD units 120 in each macropixel can be adjusted to adjust the received PDE of each macropixel, thereby adjusting the received dynamic range of each macropixel.

[0072] In some embodiments, such as Figure 7a As shown, within a macro pixel, the first SPAD unit 110 and the second SPAD unit 120 are spaced apart.

[0073] In some embodiments, depending on application requirements, such as Figure 7a As shown, within the same macro pixel, the first SPAD unit 110 and the second SPAD unit 120 are arranged at intervals, which can simultaneously detect distant low light (high PDESPAD signal output) and close-range high reflective strong light signal (low PDE and Low Jitter SPAD signal output) in any local area, avoiding the loss of close-range high reflective information due to local overexposure of the scene.

[0074] In some embodiments, the ratio of the number of the first SPAD unit 110 and the second SPAD unit 120 within the macropixel can be adjusted according to the detection requirements of different regions.

[0075] In some embodiments, if the detection requirement for the central region within a macropixel is relatively high, such as Figure 7bAs shown, a second SPAD unit 120 with lower PDE and smaller Jitter can be disposed in the center of the macro pixel, and a first SPAD unit 110 with higher PDE and larger Jitter can be disposed around the second SPAD unit 120.

[0076] In some embodiments, if the detection requirements for the edge region within a macropixel are relatively high, such as Figure 7c As shown, a first SPAD unit 110 with a higher PDE and a larger Jitter can be disposed in the center of the macro pixel, and a second SPAD unit 120 with a lower PDE and a smaller Jitter can be disposed around the first SPAD unit 110.

[0077] In some embodiments, depending on application requirements, such as Figure 7d As shown, within a macropixel, the first SPAD unit 110 and the second SPAD unit 120 can be arranged in a linear array.

[0078] In some embodiments, the macropixel includes a first detection region and a second detection region, such as Figure 5 As shown, the first detection area includes multiple first SPAD units 110, such as... Figure 6 As shown, the second detection area includes multiple second SPAD units 120, and the first detection area and the second detection area are arranged adjacent to each other within the macropixel.

[0079] In some embodiments, a macropixel includes a plurality of first detection regions and a plurality of second detection regions, wherein the first detection regions and the second detection regions are spaced apart.

[0080] This application embodiment also includes a receiving sensor, which may include multiple receiving units as described in any of the above embodiments, and the multiple receiving units form a receiving array.

[0081] In this embodiment, the receiving sensor may include multiple receiving units as described in the above embodiments, and the multiple receiving units form a receiving array, such as... Figure 8a As shown, a macropixel can be arranged as a receiving unit, with the receiving sensor containing multiple receiving units. These receiving units include high-PDE and low-Jitter SPAD units, enabling better scene adaptability. Specifically, the active zone can be switched in real-time based on the input light intensity; for example, high-PDE SPAD units are activated in low light, while low-Jitter SPAD units are switched in near-field strong light. This scheme ensures consistent pixel circuitry within each zone, reducing the risk of cross-pixel signal coupling and simplifying the design of quenching and signal readout circuits to some extent.

[0082] In some embodiments, each receiving unit includes a first SPAD unit 110 and a second SPAD unit 120. The first SPAD unit 110 fully utilizes the thicker epitaxial layer 200 as an epitaxial absorption layer, resulting in a higher PDE and thus a relatively larger Jitter. The first SPAD unit 110 can be responsible for distance measurement capabilities where ranging accuracy requirements are relatively low. The second SPAD unit 120 has a lower PDE and less Jitter, enabling the receiving sensor to simultaneously optimize both short-range ranging accuracy and long-range distance measurement capabilities.

[0083] The receiving unit within the receiving sensor can be as follows: Figure 8a As shown, SPAD units are arranged in an array, with high PDE and low Jitter cells arranged in a partitioned macropixel layout. This allows for better scene adaptability, meaning the active partition is switched in real time based on the input light intensity. For example, high PDE macropixels are activated in low light, while low-Jitter macropixels are switched in close-range strong light. This scheme ensures consistent pixel circuitry within each partition, reducing the risk of cross-pixel signal coupling and simplifying the design of quenching and signal readout circuits to some extent.

[0084] In some embodiments, the receiving sensor may include multiple receiving units, each of which serves as a macropixel, such as... Figure 8b The receiver array shown may include, within the receiver sensor, such as Figure 5 , Figure 6 , Figure 7b as well as Figure 7c The macro pixels shown can be arranged according to application requirements.

[0085] In some embodiments, the ratio of the number of the first SPAD unit 110 and the second SPAD unit 120 inside the receiving sensor can be adjusted according to the detection requirements of different areas, such as... Figure 8c In the receiver array shown, if the detection requirements of the central region of the receiver sensor are relatively high, the macro pixels composed of the second SPAD unit 120 with lower PDE and smaller Jitter can be set in the central region of the receiver sensor, and the macro pixels composed of the first SPAD unit 110 with higher PDE and larger Jitter can be set in the peripheral region of the macro pixels composed of the second SPAD unit 120.

[0086] In some embodiments, if the detection requirement for the central region of the receiving sensor is relatively high, the receiving unit for the central region of the receiving sensor can be as follows: Figure 7b or Figure 5 As shown, the receiving unit in the peripheral area of ​​the receiving sensor can be as follows: Figure 7c , Figure 7d or Figure 6 As shown.

[0087] In some embodiments, if the detection requirements for the edge region of the receiving sensor are relatively high, such as Figure 8d As shown, macro pixels composed of a first SPAD unit 110 with higher PDE and larger Jitter can be disposed in the central region of the receiving sensor, while macro pixels composed of a second SPAD unit 120 with lower PDE and smaller Jitter can be disposed around the first SPAD unit 110.

[0088] In some embodiments, if the detection requirements for the edge region of the receiving sensor are relatively high, the receiving unit for the central region of the receiving sensor can be as follows: Figure 7c , Figure 7d or Figure 6 As shown, the receiving unit in the peripheral area of ​​the receiving sensor can be as follows: Figure 7b or Figure 5 As shown.

[0089] In some embodiments, such as Figure 8e The receiver array shown can also arrange different types of macro pixels at intervals, so that it can simultaneously detect distant low light (high PDE SPAD signal output) and close-range high reflectivity strong light signal (low PDE and Low Jitter SPAD signal output) in any local area of ​​the receiver array, avoiding the loss of close-range high reflectivity information due to local overexposure of the scene.

[0090] It should be noted that, based on actual application requirements, the types, quantities, and arrangement schemes of SPAD units constituting the receiving unit are diverse. The receiving sensor in this embodiment includes, but is not limited to, those described above. Figure 5 , Figure 6 , Figure 7a , Figure 7b , Figure 7c as well as Figure 7d The receiving unit layout is as follows: in the receiving sensor, each receiving unit acts as a macropixel to receive the echo of the probe laser. There are countless combinations of the number and specifications of MxN macropixels, where M is the number of rows of SPAD units in the macropixel and N is the number of columns of SPAD units in the macropixel. All applications involving the combination of high PDE and low Jitter SPAD are within the protection scope of this patent.

[0091] 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.

[0092] In this embodiment, the receiving sensor may include one or more receiving units as described in the above embodiments. The receiving unit includes a first SPAD unit 110 and a second SPAD unit 120. The first SPAD unit 110 has high photon detection efficiency and low timing jitter. By setting an epitaxial isolation layer 610 in the second SPAD unit 120, its epitaxial layer 200 is divided into a design dead zone 220 and an epitaxial absorption region 210. The epitaxial absorption region 210 covers the avalanche main junction, and the design dead zone 220 is located on the epitaxial isolation layer 610. By adjusting the thickness of the design dead zone 220 through the epitaxial isolation layer 610, the thickness of the epitaxial absorption region 210 can be freely adjusted. This allows the receiving unit to meet the device requirements of various lower photon detection efficiencies and lower timing jitter. In this way, SPAD devices with various photon detection efficiencies and timing jitter levels can be realized simultaneously, meeting the synchronous optimization of short-range ranging accuracy and long-range ranging capability in radar module applications.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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 receiving unit, characterized by The receiving unit at least comprises a first SPAD unit and a second SPAD unit. The first SPAD unit and the second SPAD unit comprise an N-type heavily doped region, a cathode electrode, an anode electrode, a P-type well region, an N-type well region, a P-type hole conductive region, a P-type heavily doped region, and an epitaxial layer, the P-type well region and the N-type well region form an avalanche main junction, the epitaxial layer covers the avalanche main junction, the P-type hole conductive region covers the epitaxial layer, the N-type well region is connected to the cathode electrode through the N-type heavily doped region, and the P-type hole conductive region is connected to the anode electrode through the P-type heavily doped region. The second SPAD unit further comprises an epitaxial isolation layer, the epitaxial isolation layer is used to divide the epitaxial layer into a design dead zone and an epitaxial absorption zone, the epitaxial absorption zone covers the avalanche main junction, and the design dead zone is located on the epitaxial isolation layer.

2. The receiving unit of claim 1, wherein, The receiving unit further comprises: an anode metal wiring layer, the anode electrodes of adjacent SAPD units are interconnected through the anode metal wiring layer.

3. The receiving unit of claim 1, wherein, The receiving unit further comprises: a plurality of microlenses, the microlenses are used to converge incident light onto corresponding SPAD units.

4. The receiving unit of claim 1, characterized in that The receiving unit further comprises: a deep trench isolation column, arranged between adjacent SPAD units, for isolating adjacent SPAD units; and / or a back metal mesh, used to connect the SPAD units and corresponding external electrodes.

5. The receiving unit according to any of claims 1-4, characterized by The receiving unit comprises a plurality of SPAD units, the plurality of SPAD units are arranged in M rows of SPAD units and N columns of SAPD units. The plurality of SPAD units comprise the first SPAD unit and the second SPAD unit.

6. The receiving unit of claim 5, wherein, The first SPAD unit and the second SPAD unit are arranged in a spaced manner.

7. The receiving unit according to any of claims 1-4, characterized by The receiving unit comprises a first detection region and a second detection region, the first detection region comprises a plurality of first SPAD units, the second detection region comprises a plurality of second SPAD units, and the first detection region and the second detection region are arranged in an adjacent manner.

8. The receiving unit of claim 7, wherein, The receiving unit comprises a plurality of first detection regions and a plurality of second detection regions, and the first detection regions and the second detection regions are arranged in a spaced manner.

9. A receiving sensor, characterized by The receiving sensor comprises a plurality of receiving units as claimed in any one of claims 1-8, and the plurality of receiving units form a receiving array.

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

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