Receiving unit, receiving sensor and laser radar

Abstract

The invention 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 high photon detection efficiency and time jitter, an epitaxial isolation layer is arranged in the second SPAD unit to divide an epitaxial layer into a design dead zone and an epitaxial absorption zone, and the first SPAD unit has high photon detection efficiency and time jitter. The epitaxial absorption region covers the avalanche main junction, the design dead region is located on the epitaxial isolation layer, the thickness of the design dead region is regulated and controlled through the epitaxial isolation layer, the thickness of the epitaxial absorption region can be freely regulated and controlled, and therefore the receiving unit can meet various device requirements for low photon detection efficiency and smaller time jitter. According to the SPAD device, multiple photon detection efficiencies and time jitter levels can be synchronously realized, and synchronous optimization of short-distance measurement precision and long-distance measurement capability in radar module application is satisfied.

Description

Technical Field

[0001] The present application belongs to the technical field of optical devices, and in particular relates to a receiving unit, a receiving sensor and a laser radar. Background Art

[0002] A single-photon avalanche diode (SPAD) is a specialized PN junction sensor operating in Geiger mode. It can absorb, convert, and output electrical pulse signals down to the single-photon level, demonstrating exceptionally high detection sensitivity. Due to their high sensitivity to single-photon intensities, high temporal resolution, and robust interference resistance, single-photon avalanche diode arrays (SPADs) have been widely used in applications such as laser detection and ranging (Lidar), autonomous driving, fluorescence lifetime imaging, quantum communications, and biomedical imaging. These devices, comprised of at least two SPADs connected in parallel and functioning as a single-point silicon photomultiplier (SiPM), have been widely adopted.

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

[0004] In order to solve the above technical problems, the embodiments of the present application provide a receiving unit, a receiving sensor and a laser radar, which aim to solve the problem that the current receiving unit cannot take into account both short-distance test accuracy and long-distance measurement capability.

[0005] A first aspect of an embodiment of the present application provides a receiving unit, the receiving unit comprising at least: a first SPAD unit and a second SPAD unit; 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 conduction 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 conduction region covers the epitaxial layer, the N-type well region is connected to the cathode electrode via the N-type heavily doped region, and the P-type hole conduction region is connected to the anode electrode via the P-type heavily doped region; The second SPAD unit further includes an epitaxial isolation layer, which is used to divide the epitaxial layer into a designed dead zone and an epitaxial absorption zone. The epitaxial absorption zone covers the avalanche main junction, and the designed dead zone is located on the epitaxial isolation layer.

[0006] In some embodiments, the receiving unit further includes: An anode metal wiring layer, through which the anode electrodes of adjacent SAPD units are interconnected.

[0007] In some embodiments, the receiving unit further includes: A plurality of micro lenses are used to focus incident light onto corresponding SPAD units.

[0008] In some embodiments, the receiving unit further includes: Deep trench isolation columns are provided between adjacent SPAD units to isolate adjacent SPAD units; and / or The back metal grid is used to connect the SPAD unit to the corresponding external electrode.

[0009] In some embodiments, the receiving unit includes a plurality of SPAD units, and the plurality of SPAD units are arranged in M ​​rows of SPAD units and N columns of SAPD units; The plurality of SPAD units include the first SPAD unit and the second SPAD unit.

[0010] In some embodiments, the first SPAD unit and the second SPAD unit are spaced apart.

[0011] In some embodiments, the receiving unit includes a first detection area and a second detection area, the first detection area includes a plurality of the first SPAD units, the second detection area includes a plurality of the second SPAD units, and the first detection area is adjacent to the second detection area.

[0012] In some embodiments, the receiving unit includes a plurality of first detection areas and a plurality of second detection areas, and the first detection areas are spaced apart from the second detection areas.

[0013] A second aspect of an embodiment of the present application further 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.

[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: the receiving unit includes a first SPAD unit and a second SPAD unit, the first SPAD unit has high photon detection efficiency and time jitter, and an epitaxial isolation layer is set in the second SPAD unit to divide its epitaxial layer into a designed dead zone and an epitaxial absorption zone, the epitaxial absorption zone covers the avalanche main junction, and the designed dead zone is located on the epitaxial isolation layer. The thickness of the designed dead zone is regulated by the epitaxial isolation layer, and the thickness of the epitaxial absorption zone can be freely regulated, so that the receiving unit can achieve a variety of device requirements with lower photon detection efficiency and smaller time jitter. In this way, SPAD devices with multiple photon detection efficiency and time jitter levels can be realized simultaneously to meet the simultaneous optimization of short-range ranging accuracy and long-range ranging capability in radar module applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the receiving unit provided in the embodiment of the present application Figure 1 ; Figure 2 This is a schematic diagram of the receiving unit provided in the embodiment of the present application Figure 2 ; Figure 3a-3c This is a process flow diagram of a receiving unit provided in an embodiment of the present application; Figure 4a-4d This is a process flow diagram of a receiving unit provided in an embodiment of the present application; Figure 5 This is a horizontal schematic diagram of a portion of a receiving unit provided in an embodiment of the present application; Figure 6 This is a horizontal schematic diagram of a portion of a receiving unit provided in an embodiment of the present application; Figure 7a-7d This is a horizontal schematic diagram of a portion of a receiving unit provided in an embodiment of the present application; Figure 8a-8e It is a horizontal schematic diagram of a partial area of ​​the receiving sensor provided in an embodiment of the present application. 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 diode arrays (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 medium- and long-range DTOF lidar applications, the maximum detection distance is generally over 150m, requiring a strong pulsed laser power paired with a SPAD device with a large PDE to achieve the ranging requirements. Since the laser echo intensity is inversely correlated with the square of the distance, the laser intensity is higher for measuring close-range objects. In particular, the echo intensity of close-range highly reflective objects is even greater, and the requirements for the SPAD PDE are relatively lower. In fact, close-range highly reflective echoes can cause a large number of photogenerated carriers to be injected into the dead zone of the device, resulting in a large number of delayed pulses, affecting the resolution and measurement of close objects. In addition, close-range applications often place higher requirements on ranging accuracy, which requires the SPAD to have lower time jitter to reduce precision errors. Conversely, for longer-range detection, the laser echo signal is relatively weak. To detect weak echo signals, a device with a higher PDE is required. At the same time, the test accuracy requirements for long-range applications can be appropriately reduced, and the requirements for SPAD jitter can be relatively relaxed.

[0023] In order to solve the contradiction between the short-range test accuracy and the long-range measurement capability in the above-mentioned medium- and long-range radar applications, the embodiment of the present application provides a receiving unit, see 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 conductive 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 conduction 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 conduction region 600 is connected to the anode electrode 521 via the P-type heavily doped region 103; wherein, the second SPAD unit 120 also includes an epitaxial isolation layer 610, and the epitaxial isolation layer 610 is used to divide the epitaxial layer 200 into a designed dead zone 220 and an epitaxial absorption zone 210, the epitaxial absorption zone 210 covers the avalanche main junction, and the designed dead zone 220 is located on the epitaxial isolation layer 610.

[0024] In this embodiment, the P-type well region 101 and the N-type well region 102 are doped regions of different polarities, forming a PN junction between them. The first SPAD cell 110 utilizes the relatively thick epitaxial layer 200 as an epitaxial absorption layer, resulting in a high PDE (Peripheral Decomposition) and relatively high jitter. The first SPAD cell 110 can be used for distance measurement, which requires relatively low ranging accuracy. The second SPAD cell 120, by adding an epitaxial isolation layer 610 and adjusting the thickness of the dead zone 220, can reduce the light absorption volume in the device's active working area (epitaxial absorption region 210). Furthermore, the dead zone 220 acts as an effective light absorption attenuation layer, further reducing the intensity of light incident on the device's active photoelectric conversion region. This reduces the number of photogenerated carriers in the non-depletion region caused by transient strong light, significantly reducing the probability of delayed pulses. The thinner thickness of the photoelectric conversion region significantly reduces the transport path of photogenerated carriers within the active working area, significantly improving the jitter characteristics of the SPAD's response to incident light. The thickness of the epitaxial absorption region 210, which plays a decisive role in photoelectric conversion, is freely controlled by the epitaxial isolation layer 610 within the second SPAD unit 120 to meet the needs of various devices with lower PDE and smaller jitter. In this way, the receiving unit can simultaneously implement SPAD devices with various PDE and jitter levels, and match them with the 2-transmit 2-receive or multi-transmit multi-receive strategies for short-range transmission and medium- and long-range transmission in radar module applications to achieve simultaneous optimization of short-range ranging accuracy and long-range ranging capability.

[0025] In some embodiments, the P-type well region 101 is formed on the N-type well region 102 to form a SPAD unit with an N-on-P device structure, and the avalanche main junction is composed of the P-type well region 101 and the N-type well region 102.

[0026] 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. The doping concentration of the P-type well region 101 is 5E16-5E17 cm -3 The doping concentration of the N-type well region 102 is 5E17-5E18. By adjusting the main junction doping, a breakdown voltage of the order of 20-30 V can be achieved, which is used for SPAD units in the infrared band.

[0027] In some embodiments, the junction depth between the P-type well region 101 and the N-type well region 102 is between 0.5 μm and 1.5 μm.

[0028] In some embodiments, the cathode electrode 511 is led out to the cathode metal wiring layer 510 through the N-type heavily doped region 104 and the metal electrode in the N-type well region 102 .

[0029] In some embodiments, the anode electrode 521 is led out to the anode metal wiring layer 520 through the P-type heavily doped region 103 and the metal electrode in the P-type hole conductive region 600 .

[0030] In some embodiments, the P-type hole conductive region 600 is moderately P-type doped (its doping concentration can range from E16 to E18 cm-3) and has three main functions: 1) providing an equipotential potential surrounding the main absorption region of the SPAD unit to assist in the formation of the depletion region electric field; 2) collecting holes and providing a low-resistance hole conduction loop; 3) pinning interface defects caused by the DTI (Deep Trench Isolation) structure process between SPAD units to reduce DCR.

[0031] In some embodiments, the epitaxial absorption region 210 is lightly doped P-type (its doping concentration may be in the range of E14-E15 cm -3 ), which is conducive to achieving the breakdown voltage and the maximum depletion of the main absorption region under a certain degree of overbias to maximize the charge collection efficiency.

[0032] In some embodiments, see Figure 2 As shown, the receiving unit further includes: an anode metal wiring layer 520 , and the anode electrodes 521 of adjacent SAPD units are interconnected through the anode metal wiring layer 520 .

[0033] In some embodiments, see Figure 2 As shown, the receiving unit further includes: a plurality of micro lenses 430, and the micro lenses 430 are used to converge the incident light onto the corresponding SPAD units.

[0034] In this embodiment, at least two SPAD units form a SPAD array, and each SPAD unit is provided with a corresponding microlens 430, which is used to converge the incident light onto the corresponding SPAD unit. In some embodiments, see Figure 2 As shown, the receiving unit further includes a deep trench isolation column 410 , which is disposed between adjacent SPAD units for isolating the adjacent SPAD units.

[0035] In this embodiment, by setting a deep trench isolation column 410 between adjacent SPAD units, the deep trench isolation column 410 can electrically isolate the adjacent SPAD units. The self-excited photons generated by the SPAD units when excited by the incident light are irradiated on the deep trench isolation column 410 and can be reflected. While increasing absorption, it also prevents the self-excited photons from crosstalking into adjacent SPAD units, reducing the overflow of self-excited photons, reducing the probability of photon crosstalk, and reducing the optical crosstalk of the device.

[0036] In some embodiments, the deep trench isolation column 410 may be made of metal tungsten, and dielectric material is filled around the deep trench isolation column 410 . The presence of the deep trench isolation column 410 reflects crosstalk photons, greatly reducing the probability of optical crosstalk.

[0037] In some embodiments, see Figure 2 As shown, the receiving unit further includes a back metal grid 420, which is used to connect the SPAD unit with the corresponding external electrode.

[0038] In some embodiments, a vertical cross-section of the back metal grid 420 is an inverted trapezoid.

[0039] In some embodiments, a vertical cross-section of the back metal grid 420 is a multi-layer stepped structure, and the width of each step in the multi-layer stepped structure gradually increases.

[0040] In some embodiments, the vertical cross-section of the back metal grid 420 is an arc-shaped structure, which is used to reflect photons irradiated on its surface to the SPAD unit.

[0041] In one embodiment, a vertical cross-section of the back metal grid 420 is an inverted trapezoid.

[0042] In this embodiment, since the back metal grid 420 has a regular trapezoidal shape, photons are reflected by the sidewalls of the back metal grid 420 and are likely to enter other SPAD units. Moreover, this crosstalk may propagate farther due to the smaller reflection of the lens, causing crosstalk to remote devices and further aggravating the crosstalk avalanche chain. Figure 2 As shown, in this embodiment, an inverted trapezoidal back metal grid 420 is used. At this time, the interface of the back metal grid 420 tilted inward will reflect the light incident thereon back into its own device, reducing the overflow of photons and the probability of crosstalk of self-excited photons.

[0043] In one embodiment, a vertical cross-section of the back metal grid 420 is a multi-layer stepped structure, and the width of each step in the multi-layer stepped structure gradually increases.

[0044] In this embodiment, the vertical cross-section of the back metal grid 420 is a multi-layer stepped structure, and the width of the multi-layer stepped structure increases step by step, so that the back metal grid 420 tilts inward, reflecting the light incident on it back into its own device, reducing the overflow of photons and reducing the probability of crosstalk of self-excited photons.

[0045] In one embodiment, the width of the multi-layer stepped structure increases step by step, and the width of the multi-layer stepped structure is set in an arithmetic progression.

[0046] In one embodiment, the vertical cross-section of the back metal grid 420 is an arc-shaped structure, which is used to reflect photons irradiated on its surface to the SPAD unit.

[0047] In this embodiment, by setting the vertical cross-section of the back metal grid 420 to an arc-shaped structure, the interface between the back metal grid 420 and the microlens 430 can form a total reflection interface inclined toward the inward SPAD unit, reflecting the photons irradiating its surface to the SPAD unit (that is, the interval of the SPAD unit itself), reducing the overflow of self-excited photons and reducing the probability of crosstalk of self-excited photons.

[0048] In some embodiments, in an array-packaged photodetector device, a trench structure may be etched in the package structure to reduce crosstalk between device units.

[0049] In one embodiment, the back metal grid 420 is aluminum.

[0050] In some embodiments, multiple layers of metal wiring can be formed in the cathode metal wiring layer 510 and the anode metal wiring layer 520 to lead the other electrode of the SPAD unit to the front electrode, and can also output corresponding electrical signals through the front metal wiring layer.

[0051] In some embodiments, the N-type well region 102 is formed on the P-type well region 101 to form a SPAD unit with an N-on-P device structure. Compared with 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.

[0052] In some embodiments, as Figure 3a-3c As shown, it can be realized by ion implantation in the front-end process, combined with Figure 3a As shown, under the cover of the mask 711, the region of the epitaxial isolation layer 610 is defined, the epitaxial isolation layer 610 is formed by ion implantation, and the P-type hole conductive region 600 is formed by ion implantation under the cover of the mask 712, as shown in FIG. Figure 3b The multi-layer mask 713 is used to continue ion implantation 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 the ion implantation is completed, rapid annealing (RTA) is activated. The implantation depth of the epitaxial isolation layer 610 is optimized based on the target PDE and jitter requirements. It should be noted that deeper implanted well layers require thicker photoresist (PR) or hard dielectric mask (Hard Mask). This example only provides two different PDE and jitter requirements. In fact, by adding layouts with different masks 711, the design can be expanded to device designs with different PDE and jitter levels in a step-by-step manner. No changes are required to the passivation, metal interconnect, and BSI processes following the front-end process.

[0053] In some embodiments, as Figure 4a-4d As shown, the depth of different Well isolation layers can be controlled by epitaxy, injection and multiple epitaxy. First, a mask 721 is covered on the thinner epitaxial layer 200 to perform shallow injection of the epitaxial isolation layer 610, as shown in FIG. Figure 4a Then, the P-type hole conductive region 600 is injected, as shown. Figure 4b After debonding and cleaning, epitaxial thin films are grown to increase the effective absorption area of ​​high PDE devices, as shown in Figure 4c As shown, the height of the hole conductive region is then increased to the surface by photolithography and ion implantation, as shown in FIG. Figure 4d As shown. The subsequent ion implantation can refer to Figure 3c In this embodiment, the multi-step epitaxial growth method can avoid the high-energy implantation equipment requirements of deep implantation.

[0054] In some embodiments, the receiving unit includes a plurality of SPAD units, and the plurality of SPAD units are arranged in M ​​rows of SPAD units and N columns of SPAD units; the plurality of SPAD units include a first SPAD unit 110 and a second SPAD unit 120 .

[0055] In this embodiment, in the actual application of SPAD, in order 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 macro pixel, for example, Figure 5 As shown, MxN SPAD units are combined into a macro pixel and used as a detection area. 3x3 first SPAD units 110 can form a detection area array as a macro pixel, as shown in FIG. Figure 6 As shown, 3x3 second SPAD units 120 can form a detection area array as a macro pixel. In this layout, a smaller number of macro pixel SPADs will result in a limited dynamic range, while a larger number of SPAD units will result in a decrease in point cloud resolution. Figure 7a 、 Figure 7b as well as Figure 7cAs shown, a 3x3 SPAD unit macropixel can include both a first SPAD unit 110 and a second SPAD unit 120. This allows for simultaneous detection of both far-range weak light (the signal output from the high-PDE SPAD) and close-range, high-reflection, strong light (the signal output from the low-PDE and low-jitter SPADs) in any local area, preventing the loss of close-range, high-reflection information due to partial overexposure. In actual use, the output signal strengths and relative relationship of the first and second SPAD units 110, 120 can be used to fuse data from adjacent SPADs using an interpolation algorithm. This allows for simultaneous detection of both far-range weak echo signals and close-range, high-reflection object echo signals, while ensuring accurate ranging of close-range objects.

[0056] 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 relatively large jitter. The first SPAD unit 110 can be used for distance measurement, which requires relatively low ranging accuracy. The second SPAD unit 120 has a lower PDE and even lower jitter. Based 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 receive PDE and, therefore, the receive dynamic range of each macropixel.

[0057] In some embodiments, as Figure 7a As shown, within a macro pixel, the first SPAD unit 110 and the second SPAD unit 120 are arranged at intervals.

[0058] 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, so that in any local area, both long-range weak light (high PDESPAD signal output) and close-range high-reflection strong light signals (low PDE and Low Jitter SPAD signal output) can be synchronously detected, avoiding the loss of close-range high-reflection information due to local overexposure of the scene.

[0059] In some embodiments, the ratio of the number of the first SPAD units 110 to the number of the second SPAD units 120 within the macro pixel can be adjusted according to the detection requirements of different areas.

[0060] In some embodiments, if the detection requirement of the central area within the macro pixel is relatively high, such as Figure 7bAs shown, the second SPAD unit 120 with lower PDE and smaller jitter can be arranged in the center of the macro pixel, and the first SPAD unit 110 with higher PDE and larger jitter can be arranged around the second SPAD unit 120.

[0061] In some embodiments, if the detection requirements of the edge area within the macro pixel are relatively high, such as Figure 7c As shown, the first SPAD unit 110 with higher PDE and larger jitter can be arranged in the center of the macro pixel, and the second SPAD unit 120 with lower PDE and smaller jitter can be arranged around the first SPAD unit 110.

[0062] In some embodiments, depending on application requirements, such as Figure 7d As shown, within the macro pixel, the first SPAD unit 110 and the second SPAD unit 120 can be arranged in a linear array.

[0063] In some embodiments, the macro pixel includes a first detection area and a second detection area, such as Figure 5 As shown, the first detection area includes a plurality of first SPAD units 110, such as Figure 6 As shown, the second detection area includes a plurality of second SPAD units 120 , and the first detection area and the second detection area are adjacently arranged in the macro pixel.

[0064] In some embodiments, the macro pixel includes a plurality of first detection areas and a plurality of second detection areas, and the first detection areas are spaced apart from the second detection areas.

[0065] An embodiment of the present application also includes a receiving sensor, which may include multiple receiving units in any one of the above embodiments, and the multiple receiving units form a receiving array.

[0066] In this embodiment, the receiving sensor may include multiple receiving units of 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. The receiving sensor includes multiple receiving units, each of which includes high-PDE and low-jitter SPAD units. This allows for better scene adaptability, enabling real-time switching of active partitions based on input light intensity. For example, high-PDE SPAD units are enabled in low light conditions, while low-jitter SPAD units are switched in close-range strong light conditions. This solution maintains consistent pixel circuitry within the partition, reducing the risk of cross-pixel signal coupling and simplifying the design of quenching and signal readout circuits.

[0067] In some embodiments, each receiving unit includes a first SPAD unit 110 and a second SPAD unit 120. The first SPAD unit 110 utilizes the thicker epitaxial layer 200 as an epitaxial absorption layer, resulting in a higher PDE (Peripheral Delay) and relatively high jitter. The first SPAD unit 110 can be used for range measurement, which requires relatively low ranging accuracy. The second SPAD unit 120 has a lower PDE and even lower jitter, enabling the receiving sensor to achieve simultaneous optimization of both short-range ranging accuracy and long-range ranging capability.

[0068] The receiving unit in the receiving sensor can be Figure 8a Arranged as shown, the high-PDE and low-jitter SPAD units are arranged as partitioned macropixels to form an array. This allows for better scene adaptability, enabling real-time switching of partition activation based on input light intensity. For example, high-PDE macropixels are enabled in low light conditions, while low-jitter macropixels are switched to low-jitter macropixels in close-up, strong light conditions. This solution maintains consistent pixel circuitry within each partition, reducing the risk of cross-pixel signal coupling and simplifying the design of quenching and signal readout circuitry.

[0069] In some embodiments, the receiving sensor may include multiple receiving units, each receiving unit being a macro pixel. Figure 8b The receiving array shown in the figure may include the following: Figure 5 、 Figure 6 、 Figure 7b as well as Figure 7c The macro pixels shown in the figure can be arranged according to the application requirements.

[0070] In some embodiments, the number ratio of the first SPAD unit 110 and the second SPAD unit 120 in the receiving sensor can also be adjusted according to the detection requirements of different areas, such as Figure 8c In the receiving array shown, if the detection demand in the central area of ​​the receiving sensor is relatively high, the macro pixels composed of the second SPAD unit 120 with lower PDE and smaller jitter can be set in the central area of ​​the receiving sensor, and the macro pixels composed of the first SPAD unit 110 with higher PDE and larger jitter can be set in the peripheral area of ​​the macro pixels composed of the second SPAD unit 120.

[0071] In some embodiments, if the detection requirement of the central area of ​​the receiving sensor is relatively high, the receiving unit of the central area of ​​the receiving sensor can be as follows: Figure 7b or Figure 5 As shown, the receiving unit of the receiving sensor peripheral area can be as follows Figure 7c 、 Figure 7d or Figure 6 shown.

[0072] In some embodiments, if the detection requirements of the edge area of ​​the receiving sensor are relatively high, such as Figure 8d As shown, the macro pixel composed of the first SPAD unit 110 with higher PDE and larger jitter can be set in the central area of ​​the receiving sensor, and the macro pixel composed of the second SPAD unit 120 with lower PDE and smaller jitter can be set around the first SPAD unit 110.

[0073] In some embodiments, if the detection requirements of the edge area of ​​the receiving sensor are relatively high, the receiving unit of the central area of ​​the receiving sensor can be as follows: Figure 7c 、 Figure 7d or Figure 6 As shown, the receiving unit of the receiving sensor peripheral area can be as follows Figure 7b or Figure 5 shown.

[0074] In some embodiments, as Figure 8e The receiving array shown can also arrange different types of macro pixels at intervals, so that any local area of ​​the receiving array can simultaneously detect long-range weak light (signal output of high PDE SPAD) and close-range high-reflection strong light signals (signal output of low PDE and Low Jitter SPAD), avoiding the loss of close-range high-reflection information due to local overexposure of the scene.

[0075] It should be noted that based on actual application requirements, the types, quantities and arrangement layouts of the SPAD units constituting the receiving unit are varied. The receiving sensors in this embodiment include but are not limited to the above-mentioned Figure 5 、 Figure 6 、 Figure 7a 、 Figure 7b 、 Figure 7c as well as Figure 7d The receiving unit layout of the receiving sensor is as follows: each receiving unit acts as a macro-pixel to receive the echo of the detection laser. There are countless combinations of the number and specifications of MxN in the macro-pixel. M is the number of rows of SPAD units in the macro-pixel, and N is the number of columns of SPAD units in the macro-pixel. Any combination application involving high PDE and low jitter SPAD is within the scope of protection of this patent.

[0076] 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.

[0077] In this embodiment, the receiving sensor may include one or more receiving units of the above-mentioned embodiments, and 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 time jitter. By setting an epitaxial isolation layer 610 in the second SPAD unit 120, its epitaxial layer 200 is divided into a designed dead zone 220 and an epitaxial absorption zone 210. The epitaxial absorption zone 210 covers the avalanche main junction, and the designed dead zone 220 is located on the epitaxial isolation layer 610. The thickness of the designed dead zone 220 is regulated by the epitaxial isolation layer 610, and the thickness of the epitaxial absorption zone 210 can be freely regulated, so that the receiving unit can achieve a variety of device requirements with lower photon detection efficiency and smaller time jitter. In this way, SPAD devices with multiple photon detection efficiency and time jitter levels can be simultaneously realized to meet the simultaneous optimization of short-range ranging accuracy and long-range ranging capability in radar module applications.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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 receiving unit, characterized in that: The receiving unit at least includes: a first SPAD unit and a second SPAD unit; 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 conduction 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 conduction region covers the epitaxial layer, the N-type well region is connected to the cathode electrode via the N-type heavily doped region, and the P-type hole conduction region is connected to the anode electrode via the P-type heavily doped region; The second SPAD unit further includes an epitaxial isolation layer, which is used to divide the epitaxial layer into a designed dead zone and an epitaxial absorption zone. The epitaxial absorption zone covers the avalanche main junction, and the designed dead zone is located on the epitaxial isolation layer.

2. The receiving unit according to claim 1, wherein The receiving unit further includes: An anode metal wiring layer, through which the anode electrodes of adjacent SAPD units are interconnected.

3. The receiving unit according to claim 1, wherein The receiving unit further includes: A plurality of micro lenses are used to focus incident light onto corresponding SPAD units.

4. The receiving unit according to claim 1, wherein The receiving unit further includes: Deep trench isolation columns are provided between adjacent SPAD units to isolate adjacent SPAD units; and / or The back metal grid is used to connect the SPAD unit to the corresponding external electrode.

5. The receiving unit according to any one of claims 1 to 4, characterized in that: The receiving unit includes a plurality of SPAD units, and the plurality of SPAD units are arranged in M ​​rows of SPAD units and N columns of SAPD units; The plurality of SPAD units include the first SPAD unit and the second SPAD unit.

6. The receiving unit according to claim 5, wherein: The first SPAD unit and the second SPAD unit are spaced apart from each other.

7. The receiving unit according to any one of claims 1 to 4, characterized in that: 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 is adjacent to the second detection area.

8. The receiving unit according to claim 7, wherein: The receiving unit includes a plurality of first detection areas and a plurality of second detection areas, and the first detection areas are spaced apart from the second detection areas.

9. A receiving sensor, characterized in that: The receiving sensor includes a plurality of receiving units according to any one of claims 1 to 8, and the plurality of receiving units form a receiving array.

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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