A single photon avalanche diode and a method of manufacturing the same, an optical detection device and a system

Abstract

The embodiment of the present application provides a kind of single-photon avalanche diode and its manufacturing method, light detection device and system, first doping structure is formed in the side horizontal surface of second doping structure and side wall, the area adjacent to first doping structure and second doping structure is used to form avalanche region, and the high field area of corner area adjacent to second doping structure and first doping structure is more prone to form avalanche region, i.e. avalanche effect occurs in the edge region of second doping structure and first doping structure, so the probability of generating avalanche effect is larger, and the electric field provided by the covering material can make the multiple particles in the first doped material layer move from the edge to the center, facilitate the movement of photo-generated carriers in the first doped material layer to the avalanche region, thus improving the charge collection efficiency to a certain extent, so the device has higher quantum efficiency, so it can have higher light detection efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor manufacturing, and in particular to a single photon avalanche diode and a manufacturing method thereof, an optical detection device and a system. BACKGROUND

[0002] At present, optical detectors are applied in many scenarios. An optical detector can receive an optical signal, excite photoelectrons inside the optical detector and collect the photoelectrons, that is, the optical detector can generate a corresponding electrical signal based on the optical signal to realize conversion from the optical signal to the electrical signal.

[0003] For example, in a laser radar (Lidar) system, a time of flight (ToF) method can be used to detect a to-be-detected object. Specifically, a laser signal is emitted by a radar emission system, the laser signal is reflected by the to-be-detected object and then received by an optical detector, the flight (round trip) time of the laser signal is obtained by using the emission time and the receiving time of the laser signal, and thus the distance (i.e., depth information) between the Lidar system and the to-be-detected object can be determined, and then the position information of the to-be-detected object can be obtained. The Lidar system can be applied in a vehicle. With the continuous evolution of the automatic driving technology of the vehicle, the demand for automatic driving level is continuously increasing, and the demand for the perception ability of the vehicle is also continuously increasing, and therefore a higher-performance optical detector is needed in the Lidar system. In addition, an optical detector can also be arranged in other terminals and wearable devices having a photoelectric conversion function.

[0004] As a component of an optical detector, a single photon avalanche diode (SPAD) works in the following way. Under the action of a photoelectric effect, photo-generated carriers (electron-hole pairs) generated by an optical signal are rapidly accelerated when moving in a high electric field region (a reverse voltage of a PN junction). During the movement, one or more collisions can occur, and new secondary and tertiary electron-hole pairs are generated through collision ionization effect, an avalanche multiplication effect is generated, the number of carriers is rapidly increased, and a relatively large photo-generated current is formed. Therefore, the single photon avalanche diode can detect very weak photons (up to the order of a single photon), and sample and calculate the light field of an imaging target in time and space.

[0005] A single photon avalanche diode is a basic device of many photoelectric devices, and its performance affects the performance of the photoelectric device. For example, in a direct time of flight (DToF) system, the response capability of a single photon avalanche diode to photons, i.e., the photon detection efficiency (PDE), is crucial to the performance of the DToF system. However, the current single photon avalanche diode has a low light detection efficiency, because in a device with a high avalanche probability, the quantum efficiency (QE) is usually low, and in a device with a high quantum efficiency, the avalanche probability is usually low. Therefore, in order to achieve better performance of the photoelectric device, it is urgent to improve the performance of the single photon avalanche diode. SUMMARY

[0006] Therefore, the first aspect of the present application provides a single photon avalanche diode and a manufacturing method thereof, a light detection device and a system, which can improve the light detection efficiency.

[0007] The first aspect of the embodiments of the present application provides a single photon avalanche diode, which comprises a first doped material layer, a second doped structure, a first doped structure and a covering material. The first doped material layer and the second doped structure are stacked in the longitudinal direction, and the cross section of the second doped structure is smaller than that of the first doped material layer. The doping types of the first doped material layer and the second doped structure are consistent, and the doping concentration of the second doped structure is higher than that of the first doped material layer. The first doped structure covers the surface of the second doped structure facing the first doped material layer and the sidewall of the second doped structure. The doping type of the first doped structure is opposite to that of the second doped structure. The region adjacent to the second doped structure and the first doped structure is used to form an avalanche region. The covering material covers the surface of the first doped material layer to provide an electric field for moving the multiple carriers in the first doped material layer from the edge to the center.

[0008] That is, in the embodiments of the present application, the first doped structure is formed on the horizontal surface and the sidewall of the second doped structure. The region adjacent to the second doped structure and the first doped structure is used to form an avalanche region. The high field region of the corner region adjacent to the second doped structure and the first doped structure is more prone to form an avalanche region, i.e., the avalanche effect occurs in the edge region of the second doped structure and the first doped structure, so the probability of generating an avalanche effect is relatively high. The covering material can provide an electric field for moving the multiple carriers in the first doped material layer from the edge to the center, which is beneficial to the movement of the photo-generated carriers in the first doped material layer to the avalanche region. Therefore, the charge collection efficiency is improved to a certain extent, and therefore the device has a high quantum efficiency, so that it can have a high light detection efficiency.

[0009] As a possible implementation, the single-photon avalanche diode further comprises a third doped structure.

[0010] When the first doped structure covers the part of the sidewall of the second doped structure close to the first doped material layer, the third doped structure is located on the part of the sidewall of the second doped structure not covered by the first doped structure, or the third doped structure is located between the second doped material layer and the third doped material layer, and the part of the sidewall of the second doped structure not covered by the first doped structure.

[0011] The doping type of the third doped structure is consistent with that of the second doped structure, and the doping concentration is lower than that of the second doped structure.

[0012] In the embodiments of the present application, the third doped structure can be formed to cover the part of the sidewall of the second doped structure away from the first doped material layer, and the doping type of the third doped structure is consistent with that of the second doped structure, and the doping concentration is lower than that of the second doped structure. In this way, when the surface of the first doped material layer where the second doped structure is formed is covered by the covering material, the third doped structure can form a sidewall with the second doped structure, thereby serving as a buffer layer between the second doped structure and the covering material, reducing the surface potential of the device plane formed by the second doped structure and the covering material, and reducing the dark current at the device plane.

[0013] As a possible implementation, the first doped structure longitudinally penetrates the first doped material layer.

[0014] In the embodiments of the present application, the first doped structure can longitudinally penetrate the first doped material layer, so that the electric field generated by the first doped structure can cause the photo-generated carriers in the first doped material layer to move away from the first doped structure, thereby gathering the photo-generated carriers to the central position between the first doped structure and the filling material, thereby improving the quantum efficiency.

[0015] As a possible implementation, the covering material is a fourth doped structure and / or a dielectric layer, the dielectric layer is charged, the doping type of the fourth doped structure is opposite to that of the first doped material layer, and the charge type of the dielectric layer is the same as that of the majority carriers in the first doped material layer.

[0016] In the embodiments of the present application, the covering material can be a third doped structure and / or a dielectric layer, and the dielectric layer can be charged, so that the electric field generated by the third doped material structure and / or the dielectric layer can promote the movement of the carriers to the center of the first doped material layer, thereby improving the charge collection efficiency.

[0017] As a possible implementation, the covering material is connected to the first lead, and the first lead and the second doped structure are respectively connected to different bias voltages.

[0018] In the embodiments of the present application, the covering material and the first lead-out end are connected, and the first lead-out end can be connected to different bias voltages respectively through the second doping structure, so as to promote charge collection and provide control voltage for the single photon avalanche diode.

[0019] As a possible implementation, the second doping structure is located in the middle of the first doping material layer, or the second doping structure is arranged along the edge of the first doping material layer, or the second doping structure is located at the top corner position of the first doping material layer.

[0020] In the embodiments of the present application, the second doping structure can be located at different positions of the first doping material layer, so that the structure of the single photon avalanche diode is different, and it is more adaptable to different scenes.

[0021] As a possible implementation, the single photon avalanche diode further comprises a substrate;

[0022] The first doping material layer and the second doping structure are sequentially arranged from bottom to top on the substrate.

[0023] In the embodiments of the present application, the single photon avalanche diode can be formed in a front-illuminated light detection device, and the first doping material layer and the second doping structure are sequentially arranged from bottom to top on the substrate, which is conducive to the connection of the second doping structure.

[0024] As a possible implementation, the single photon avalanche diode further comprises a substrate;

[0025] The second doping structure and the first doping material layer are sequentially arranged from bottom to top on the substrate.

[0026] In the embodiments of the present application, the single photon avalanche diode can be formed in a back-illuminated light detection device, and the second doping structure and the first doping material layer are sequentially arranged from bottom to top on the substrate, so that light can directly irradiate the first doping material layer from top to bottom without being blocked, which is conducive to improving the light absorption efficiency.

[0027] As a possible implementation, the single photon avalanche diode further comprises a microlens layer;

[0028] The microlens layer is located on the side surface away from the substrate; and the focus of the microlens layer is between the edge of the first doping material layer and the second doping structure.

[0029] In the embodiments of the present application, the single photon avalanche diode can further include a microlens layer, the microlens layer can be located on the side surface away from the substrate, and the microlens layer can focus between the edge of the first doped material layer and the second doped structure, so that the light can pass through the microlens layer to the first doped material layer and be focused, thereby improving the light conversion efficiency.

[0030] As a possible implementation, the microlens layer is an array of microlenses, and the microlens includes a convex lens and / or a Fresnel lens.

[0031] In the embodiments of the present application, the microlens layer can be an array of microlenses, and the microlens can be a convex lens and / or a Fresnel lens, thereby realizing focusing of the light beam, wherein the Fresnel lens can have a smaller longitudinal size while realizing the same focusing effect as the convex lens, which is beneficial to reducing the size of the device.

[0032] As a possible implementation, the single photon avalanche diode further includes an inverted pyramid structure, and the inverted pyramid structure is located on the side away from the substrate.

[0033] In the embodiments of the present application, the single photon avalanche diode can further include an inverted pyramid structure, the inverted pyramid structure can be located on the side away from the substrate, and the inverted pyramid structure has a surface that is not parallel to the surface of the substrate, and the light beam will be refracted when passing through the inverted pyramid structure, so that the light beam incident on the first doped material layer is no longer only a longitudinal light beam, but a relatively inclined light beam, thereby increasing the transmission path length of the light beam in the first doped material layer, improving the possibility of light excitation, and improving the light conversion efficiency.

[0034] In a second aspect of the embodiments of the present application, a manufacturing method of a single photon avalanche diode is provided, including:

[0035] providing a substrate;

[0036] forming, from bottom to top, a second doped structure, a first doped structure, and a first doped material layer on the substrate; or, forming, from bottom to top, a first doped material layer, a first doped structure, and a second doped structure on the substrate;

[0037] The second doped structure has a cross section smaller than the first doped material layer; the first doped material layer and the second doped structure have the same doping type, and the second doped structure has a higher doping concentration than the first doped material layer; the first doped structure covers the surface of the second doped structure facing the first doped material layer, and covers the sidewall of the second doped structure; the first doped structure has a doping type opposite to that of the second doped structure, and the region adjacent to the first doped structure and the second doped structure is used to form an avalanche region; the surface of the first doped material layer is formed with a covering material for providing an electric field for moving the multi-carriers in the first doped material layer from the edge to the center.

[0038] As a possible implementation, the method further comprises:

[0039] forming a third doped structure;

[0040] When the first doped structure covers the part of the sidewall of the second doped structure close to the first doped material layer, the third doped structure is located on the part of the sidewall of the second doped structure not covered by the first doped structure, or the third doped structure is located between the second doped material layer and the third doped material layer, and the part of the sidewall of the second doped structure not covered by the first doped structure;

[0041] The third doped structure has the same doping type as the second doped structure, and a lower doping concentration than the second doped structure.

[0042] As a possible implementation, the first doped structure longitudinally penetrates the first doped material layer.

[0043] As a possible implementation, the covering material is a fourth doped structure and / or a dielectric layer with a charge; the fourth doped structure has a doping type opposite to that of the first doped material layer, and the dielectric layer has the same charge type as the multi-carriers in the first doped material layer.

[0044] As a possible implementation, the covering material is connected to a first lead, and the first lead and the second doped structure are respectively connected to different bias voltages.

[0045] As a possible implementation, the second doped structure is located in the middle of the first doped material layer, or the second doped structure is arranged along the edge of the first doped material layer, or the second doped structure is located at the top corner of the first doped material layer.

[0046] As a possible implementation, the method further comprises a microlens layer.

[0047] The microlens layer is located on a side surface away from the substrate; the microlens layer focuses between the edge of the first doped material layer and the second doped structure.

[0048] As a possible implementation, the microlens layer is an array of microlenses, the microlenses including convex lenses and / or Fresnel lenses.

[0049] As a possible implementation, the method further includes an inverted pyramid structure; the inverted pyramid structure is located away from the substrate.

[0050] In a third aspect, the application provides a light detector device, including a plurality of light detection units; the light detection unit includes a logic circuit layer and the single photon avalanche diode provided in the first aspect of the application; the logic circuit layer is electrically connected to the single photon avalanche diode.

[0051] As a possible implementation, the single photon avalanche diodes in different detection units are isolated by isolation trenches.

[0052] As a possible implementation, the isolation trenches are filled with insulating materials; or a dielectric layer is formed on the sidewall of the isolation trench, and a metal filling layer is further filled in the isolation trench.

[0053] In a fourth aspect, the application provides a light detection system, including a light emitter device and the light detector device provided in the third aspect of the application.

[0054] The light emitter device is used to emit light signals to a to-be-detected object.

[0055] The light detector device is used to generate avalanche current based on the light signals reflected by the to-be-detected object.

[0056] From the above technical solutions, the application has the following advantages:

[0057] The embodiment of the present application provides a single photon avalanche diode and a manufacturing method thereof, an optical detection device and a system, wherein the single photon avalanche diode comprises a first doped material layer, a second doped structure, a first doped structure and a covering material, wherein the first doped material layer and the second doped structure are stacked in the longitudinal direction, the cross section of the second doped structure is smaller than that of the first doped material layer, the doping types of the first doped material layer and the second doped structure are consistent, the doping concentration of the second doped structure is higher than that of the first doped material layer, the first doped structure is located between the second doped structure and the first doped material layer and covers the sidewall of the second doped structure, the doping type of the first doped structure is opposite to that of the second doped structure, and the region adjacent to the first doped structure and the second doped structure is used to form an avalanche region, and the covering material is formed on the surface of the first doped material layer and is used to provide an electric field for moving the multiple carriers in the first doped material layer from the edge to the center.

[0058] That is, in the embodiment of the present application, the first doped structure is formed on the horizontal surface and the sidewall of the second doped structure, the region adjacent to the first doped structure and the second doped structure is used to form an avalanche region, the high field region of the corner region adjacent to the second doped structure and the first doped structure is more prone to form an avalanche region, that is, the avalanche effect occurs in the edge region of the second doped structure and the first doped structure, and therefore the probability of generating the avalanche effect is relatively high, and the covering material can provide an electric field for moving the multiple carriers in the first doped material layer from the edge to the center, thereby facilitating the movement of the photo-generated carriers in the first doped material layer to the avalanche region, and therefore the charge collection efficiency is improved to a certain extent, and therefore the device has a relatively high quantum efficiency, and therefore can have a relatively high light detection efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0059] In order to clearly understand the specific embodiments of the present application, the following will briefly describe the drawings used in the description of the specific embodiments of the present application. Obviously, these drawings are only part of the embodiments of the present application.

[0060] Figure 1 FIG. 1 is a structural schematic diagram of a single photon avalanche diode according to the prior art;

[0061] Figure 2 FIG. 6 is a structural schematic diagram of an optical detection system according to the embodiment of the present application;

[0062] Figure 3 FIG. 9 is a structural schematic diagram of an optical detection unit according to the embodiment of the present application;

[0063] Figure 4 FIG. 13 is a structural schematic diagram of a single photon avalanche diode according to the embodiment of the present application;

[0064] Figure 5 FIG. 16 is a structural schematic diagram of another single photon avalanche diode according to the embodiment of the present application;

[0065] Figure 6 This is a schematic diagram of the projection of the second doped structure and the first doped structure in the horizontal plane in the embodiments of this application;

[0066] Figure 7 A schematic diagram of an equipotential line provided in an embodiment of this application;

[0067] Figure 8 A schematic diagram of another single-photon avalanche diode provided in this application embodiment;

[0068] Figure 9 This is a schematic diagram of the structure of another single-photon avalanche diode in the embodiments of this application;

[0069] Figure 10 for Figure 9 A schematic diagram of the projection of each component in the horizontal plane;

[0070] Figure 11 A schematic diagram of the structure of another single-photon avalanche diode provided in this application embodiment;

[0071] Figure 12 A schematic diagram of the structure of another single-photon avalanche diode provided in this application embodiment;

[0072] Figure 13 A flowchart illustrating a method for manufacturing a single-photon avalanche diode, as provided in an embodiment of this application. Detailed Implementation

[0073] This application provides a semiconductor device and its manufacturing method, a photodetector and system, which can improve photodetection efficiency.

[0074] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0075] The application is described in detail in combination with the schematic diagram. In the detailed description of the embodiments of the application, the sectional view of the device structure is partially enlarged without the general proportion for the convenience of illustration, and the schematic diagram is only an example which should not limit the scope of protection of the application herein. In addition, the three-dimensional spatial dimensions of length, width and depth should be included in the actual manufacture.

[0076] At present, as a component of a light detector, the working principle of a single photon avalanche diode is to generate photo-generated carriers under the action of a light signal through photoelectric effect, which are rapidly accelerated when moving in a high electric field area. During the movement process, one or more collisions may occur, and secondary and tertiary new electron-hole pairs are generated through collision ionization effect, avalanche multiplication effect is generated, the number of carriers is rapidly increased, and relatively large photo-generated current is generated.

[0077] The inventors have found that the photo-detection efficiency of a single photon avalanche diode is jointly determined by the quantum efficiency of the single photon avalanche diode to target photons and the avalanche probability of the single photon avalanche diode itself, and the quantum efficiency of the single photon avalanche diode to target photons is usually proportional to the size of the high field area of the single photon avalanche diode. There is a trade-off between the quantum efficiency and the avalanche probability of the current single photon avalanche diode, and both cannot be optimized at the same time, resulting in that the photo-detection efficiency is limited.

[0078] Specifically, the current single photon avalanche diode utilizes the avalanche breakdown of a PN junction. The breakdown may occur at the edge or the central flat area of the PN junction. If the avalanche breakdown occurs at the edge, the avalanche probability is high, but the area of the high field area is small. If the avalanche breakdown occurs at the central flat area, the area of the high field area is large, but the avalanche probability is low.

[0079] Reference Figure 1 As shown in the figure, it is a structure schematic diagram of the current single photon avalanche diode. The upper surface of the P-type well is provided with an N+ well region. The contact area of the P-type well and the N+ well region serves as a high field area and is also an area where the avalanche effect occurs. Generally, the avalanche effect occurs at the edge first. Obviously, the quantum efficiency is low at this time. Therefore, in order to ensure a large enough high field area to achieve high quantum efficiency, a protection ring N-well around the N+ well region can be designed to avoid breakdown of the single photon avalanche diode at the edge of the PN junction, so as to utilize the central flat area of the PN junction for avalanche. The size of the central flat area is relatively large, and the photo-generated carriers generated in the P-type well have a high probability of moving to the central flat area, so as to generate the avalanche effect in the central flat area. The upper surface of the P-type well can also be provided with a P+ well region. The P+ well region and the N+ well region can be biased to promote the occurrence of the avalanche effect.

[0080] To solve the above technical problems, the single photon avalanche diode and the manufacturing method thereof, the light detection device and the system are provided in the embodiments of the present application, wherein the single photon avalanche diode can include a first doped material layer, a second doped structure, a first doped structure and a covering material, the first doped material layer and the second doped structure are stacked in the longitudinal direction, the cross section of the second doped structure is smaller than that of the first doped material layer, the doping type of the first doped material layer and the second doped structure is consistent, the doping concentration of the second doped structure is higher than that of the first doped material layer, the first doped structure is located between the second doped structure and the first doped material layer and covers the sidewall of the second doped structure, the doping type of the first doped structure is opposite to that of the second doped structure, and the region adjacent to the first doped structure and the second doped structure is used to form an avalanche region, and the covering material is formed on the surface of the first doped material layer to provide an electric field for moving the multiple carriers in the first doped material layer from the edge to the center.

[0081] That is, in the embodiments of the present application, the first doped structure is formed on the horizontal surface and the sidewall of the second doped structure, the region adjacent to the first doped structure and the second doped structure is used to form an avalanche region, and the high field region of the corner region adjacent to the second doped structure and the first doped structure is more prone to form an avalanche region, that is, the avalanche effect occurs in the edge region of the second doped structure and the first doped structure, so that the probability of generating an avalanche effect is higher, and the covering material can provide an electric field for moving the multiple carriers in the first doped material layer from the edge to the center, which is beneficial to the movement of the photo-generated carriers in the first doped material layer to the avalanche region, thereby improving the charge collection efficiency to a certain extent, so that the device has a higher quantum efficiency, thereby having a higher light detection efficiency.

[0082] In order to make the above objects, features and advantages of the present application more apparent and understandable, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0083] Reference Figure 2 As shown in FIG. 1, a structure schematic diagram of a light detection system is provided in the embodiments of the present application, wherein the light detection system can include a light emitting device and a light detection device, the light emitting device is used to emit a light signal to a to-be-detected object, and the light detection device can be used to generate an avalanche current based on the light signal reflected by the to-be-detected object. The time point of emitting the light signal to the to-be-detected object and the time point of generating the avalanche current can be used to determine the time of flight of the light signal, and thus the distance between the to-be-detected object and the light detection system can be calculated.

[0084] The light emitting device can be a laser array, and a collimating lens can be arranged between the light emitting device and the to-be-detected object; the light detection device can include a plurality of light detection units, the light detection units can be arranged in an array, and a filter can be arranged between the light detection device and the to-be-detected object, the filter can transmit light of a specified wavelength, for example, infrared light.

[0085] The light detection units can be isolated by an isolation trench, thereby reducing cross talk (X-talk) between different single photon avalanche diodes. Specifically, the isolation trench can be a deep trench, and the isolation method can be a deep trench isolation (DTI) process. Specifically, the isolation trench can divide the light detection device into multiple light absorption regions, and the single photon avalanche diodes can be formed in the light absorption regions. The single photon avalanche diodes can generate avalanche current based on the light signal of the light absorption region to which the single photon avalanche diode belongs. The light absorption regions can be arranged in an array, and the shape of the light absorption region can be determined according to actual conditions, for example, can be a polygon that can be closely arranged.

[0086] In the isolation trench, an insulating material can be filled to isolate different single photon avalanche diodes. In the isolation trench, a dielectric layer can also be formed on the sidewall, and then a metal filler can be used to fill the isolation trench, thereby also isolating different single photon avalanche diodes. The dielectric layer can be a high-K material, such as Al2O3, TaO, HfO, etc. The metal filler layer can be, for example, tungsten.

[0087] The insulating material or the dielectric layer can reduce the dark count of the single photon avalanche diode, i.e., reduce the avalanche current generated in the absence of a light signal, and can also reduce the leakage current of the single photon avalanche diode. The metal filler layer is generally an opaque material, which can reduce the interference of light signals between different single photon avalanche diodes.

[0088] Reference Figure 3 As shown in FIG. 1A, a structure schematic diagram of a light detection unit provided by an embodiment of the present application is shown, wherein the light detection unit can include a logic circuit layer and a single photon avalanche diode. The logic circuit layer can include an image signal processor (ISP) unit, which can process the avalanche current. For example, the number of photons that generate the avalanche current can be calculated according to the change in the avalanche current. The single photon avalanche diode can generate a photoelectric effect under the irradiation of light, generate photo-generated carriers inside, and the photo-generated carriers move and amplify under the action of an electric field to obtain an avalanche current.

[0089] The logic circuit layer and the single photon avalanche diode can be disposed on different layers of the same substrate. For example, the logic circuit layer can be disposed between the substrate and the single photon avalanche diode, forming a back-illumination structure of the light detection device, as shown in FIG. 1B. Figure 3 As shown in FIG. 1C, the logic circuit layer can also be disposed on the substrate, and the single photon avalanche diode disposed thereon can be disposed on the same layer, forming a front-illumination structure of the light detection device, as shown in FIG. 1C. Figure 3 As shown in FIG. 1A, the arrowed parallel lines can indicate the direction of light.

[0090] The logic circuit layer can further include a control unit, which can control the working state of the light detection unit, for example, control the input voltage of the light detection unit. The control unit and the image signal processor can be arranged in the same layer or different layers.

[0091] The light emitting device can further be provided with a control circuit for controlling the light emitting device to emit light signals.

[0092] The single photon avalanche diode provided by the embodiment of the present application will be described below with reference to the accompanying drawings.

[0093] Reference Figure 4 As shown in the figure, the structure of a single photon avalanche diode provided by the embodiment of the present application, which can include a first doped material layer 110, a second doped structure 120 and a first doped structure.

[0094] The first doped material layer 110 and the second doped structure 120 can be stacked in the longitudinal direction, and the cross section of the second doped structure 120 can be smaller than that of the first doped material layer 110. Of course, the first doped material layer 110 can be located above the second doped structure 120 or below the second doped structure 120, and the figure illustrates the case where the second doped structure 120 is above the first doped material layer 110. The doping types of the first doped material layer 110 and the second doped structure 120 are consistent, for example, both are P-type doping or both are N-type doping, and the doping concentration of the second doped structure 120 is higher than that of the first doped material layer 110.

[0095] For ease of description, in the embodiment of the present application, different doping can be divided into heavy doping, doping and light doping according to the doping concentration, which are used to correspond to different doping concentration intervals, wherein heavy doping can be represented by P+ or N+, doping can be represented by P or N, and light doping can be represented by P- or N-. Specifically, the first doped material layer 110 can be shallow doping, and the doping type can be represented by P- or N-, and the second doped structure 120 can be heavy doping, and the doping type can be represented by P+ or N+.

[0096] The cross section of the first doped material layer 110 can be polygonal, for example, rectangular, triangular, hexagonal, etc., and the second doped structure 120 can be located in the middle of the first doped material layer 110, or can be arranged along the edge of the first doped material layer, or can be located at the top corner of the first doped material layer.

[0097] In the embodiments of the present application, the single-photon avalanche diode can further include a first doped structure, which can cover the surface of the second doped structure 120 facing the first doped material layer 110 and cover the sidewall of the second doped structure 120. That is, when the first doped material layer 110 is located above the second doped structure 120, the first doped structure can be located on the upper surface and the sidewall of the second doped structure 120; when the first doped material layer 110 is located below the second doped structure 120, the first doped structure can be located on the lower surface and the sidewall of the second doped structure 120. The doping type of the first doped structure is opposite to that of the first doped material layer 110, and the doping type of the first doped material layer 110 is consistent with that of the second doped structure 120, so the doping type of the first doped structure is different from that of the second doped structure 120 and the first doped material layer 110. In this way, the first doped material layer 110, the first doped structure and the second doped structure 120 can form a PNP or NPN structure, and an avalanche region 122 is easily formed in the adjacent corner region of the second doped structure 120 and the first doped structure, and the carrier can enter the second doped structure 120 through the first doped structure in the corner region, wherein the size of the avalanche region 122 is determined according to actual conditions, and only one example is shown in the drawings.

[0098] Specifically, the first doped structure can include a first part 111 and a second part 112 connected to each other, the first part 111 extends longitudinally in the first doped material layer 110 and is opposite to the second doped structure 120, and the second part 112 covers the corner region formed by the sidewall of the second doped structure 120 and the surface of the second doped structure 120 facing the first doped material layer 110.

[0099] The second part 112 in the first doped structure can cover the entire sidewall of the second doped structure 120, or can only cover part of the sidewall of the second doped structure 120 close to the first doped material layer 110, can cover one side of the sidewall, or can cover multiple sides of the sidewall, can cover the entire horizontal surface of the second doped structure 120 close to the first doped material layer 110, or can only cover the edge region of the horizontal surface of the second doped structure 120 close to the first doped material layer 110.

[0100] That is, the second part 112 of the first doped structure can have a recess in which the second doped structure 120 is embedded, and the recess can be a through recess or a non-through recess. When the second part 112 of the first doped structure includes a through recess, the first part 111 of the first doped structure can be embedded in the recess of the second part 112 to be connected with the second part 112, and in this case, the size of the second part 112 of the first doped structure in the horizontal plane is smaller than that of the first part 111. When the second part 112 of the first doped structure includes a non-through recess, the first part 111 of the first doped structure can be connected with the second part 112 of the first doped structure on the side of the first doped structure away from the second doped structure 120, and in this case, the size of the second part 112 of the first doped structure in the horizontal plane can be smaller than, equal to, or greater than that of the first part 111.

[0101] The longitudinal extension length of the first part 111 of the first doped structure can be determined according to actual conditions, for example, can extend to the middle of the first doped material layer 110, or longitudinally extend through the first doped material layer 110, as shown in FIG. 1. Figure 4 The doping concentration of the first part 111 and the second part 112 of the first doped structure can be consistent or inconsistent.

[0102] It should be noted that the doping type of the first part 111 of the first doped structure is inconsistent with that of the first doped material layer 110, so that the electric field inside the first doped material layer 110 is changed, and the photo-generated carriers in the first doped material layer 110 move away from the first doped structure 111, which is beneficial to the movement of the photo-generated carriers to the position of the avalanche region and the collection of the carriers. The longer the longitudinal extension length of the first part 111 is, the more beneficial to the movement of the carriers.

[0103] In the embodiments of the present application, a voltage can be applied to the second doped structure 120 and the first doped material layer 110 to make them have a voltage difference. The second doped structure 120 can serve as a second lead-out end, and the first doped material layer 110 can be connected with a first lead-out end 143. The first lead-out end 143 and the second lead-out end can be used to apply a bias to the single-photon avalanche diode, so as to control the working state of the single-photon avalanche diode, for example, by setting the bias of the first lead-out end 143 and the second lead-out end, the single-photon avalanche diode works in the Geiger mode, so as to occur avalanche effect under the irradiation of light. The second doped structure 120 can also be used to detect avalanche current, so as to analyze the avalanche current, for example, by using the avalanche current to analyze the light signal causing the avalanche current.

[0104] For example, referring to FIG. 2, another schematic diagram of a single-photon avalanche diode provided by the embodiments of the present application is shown, wherein, Figure 5 The second doped structure 120 can be connected with a second lead-out end 143, and the first doped material layer 110 can be connected with a first lead-out end 142. The first lead-out end 142 and the second lead-out end 143 can be used to apply a bias to the single-photon avalanche diode, so as to control the working state of the single-photon avalanche diode, for example, by setting the bias of the first lead-out end 142 and the second lead-out end 143, the single-photon avalanche diode works in the Geiger mode, so as to occur avalanche effect under the irradiation of light. The second doped structure 120 can also be used to detect avalanche current, so as to analyze the avalanche current, for example, by using the avalanche current to analyze the light signal causing the avalanche current.Figure 5 A is NPN structure, that is, the doping type of the first doped material layer 110 is N-, the doping type of the first doped structure is P, the doping type of the second doped structure 120 is N+, the majority carriers in the first doped material layer 110 are electrons, and therefore the photo-generated carriers are also basically electrons; Figure 5 B is PNP structure, that is, the doping type of the first doped material layer 110 is P-, the doping type of the first doped structure is N, the doping type of the second doped structure 120 is P+, the majority carriers in the first doped material layer 110 are holes, and therefore the photo-generated carriers are also basically holes.

[0105] Specifically, the second doped structure 120 can be in an elliptical shape, a circular shape, a polygonal shape, etc. in the lateral direction, and correspondingly, the second part 112 of the first doped structure can be in an elliptical ring, a circular ring, a polygonal ring, etc. in the lateral direction. Referring to Figure 6 As shown in A, the second doped structure and the first doped structure in the horizontal plane in the embodiment of the present application are projection schematic diagrams, as shown in Figure 6 As shown in A, the second doped structure 120 forms a circular shape in the lateral direction, and the first doped structure forms a circular ring in the lateral direction; referring to Figure 6 As shown in B, the second doped structure 120 forms a rectangular shape in the lateral direction, and the first doped structure forms a rectangular ring in the lateral direction, wherein the rectangular ring can include an angle, a rounded corner or a bevel corner; referring to Figure 6 As shown in C, the second doped structure 120 can form a triangular shape in the lateral direction, and the first doped structure forms a triangular ring in the lateral direction, wherein the triangular ring can include an angle, a rounded corner or a bevel corner; referring to Figure 6 As shown in D, the second doped structure 120 can form a hexagonal shape in the lateral direction, and the first doped structure forms a hexagonal ring in the lateral direction, wherein the hexagonal ring can include an angle, a rounded corner or a bevel corner.

[0106] In the embodiment of the present application, the single photon avalanche diode can further include a covering material formed on the surface of the first doped material layer 110. Specifically, the covering material can include a first material 1411 formed on the surface of the first doped material layer 110 away from the second doped structure 120, and / or a second material 1412 formed on the sidewall of the first doped material layer 110, and / or a third material 1413 formed on the sidewall of the second doped structure 120. The covering material can also provide an electric field for the majority carriers in the first doped material layer 110 to move from the edge to the center, so that the covering material can promote the movement of the edge carriers to the center, thereby improving the charge collection efficiency. The first doped material layer 110 can be connected to the first lead by the covering material, thereby applying a bias to the single photon avalanche diode.

[0107] Referring to Figure 7The diagram shown is a schematic representation of an equipotential line provided in an embodiment of this application. Figure 5 Figure A shows a schematic diagram of the equipotential lines inside a single-photon avalanche diode. The upper center position is where the second doped structure 120 is located, and the lower center position is where the first part 111 of the first doped structure is located. The covering material includes a first material, a second material, and a third material. As can be seen from the figure, the equipotential lines form a symmetrical structure. The potential gradually increases from the outer layer to the inner layer. Therefore, the direction of the electric field lines is from the second doped structure 120 to the center position of the covering material and the first part 111 of the first doped structure, and then from that center position to the covering material and the first part 111 of the first doped structure (in the opposite direction of the dashed arrow in the figure). Therefore, electrons in the first doped material layer move against the direction of the electric field lines, referring to the direction of the dashed arrow in the figure, and thus move towards the second doped structure 120.

[0108] The covering material can be a fourth doped structure, where the doping type of the fourth doped structure is opposite to that of the first doped material layer 110. For example, if the doping type of the first doped material layer 110 is N-, then the doping type of the fourth doped structure can be P. In this case, the electric field direction is from the first doped material layer 110 to the fourth doped structure. Therefore, electrons in the first doped material layer 110 are majority carriers, and electrons at the edges move towards the center of the first doped material layer 110 under the influence of the electric field generated by the fourth doped structure. Conversely, if the doping type of the first doped structure is opposite to that of the first doped material layer 110, then when the doping type of the first doped material layer 110 is N-, the doping type of the first doped structure can also be P. In this case, the electric field direction is from the first doped material layer 110 to the first doped structure. Electrons around the first doped structure will move away from the first doped structure under the influence of the electric field. Therefore, the electrons will eventually gather between the first and fourth doped structures.

[0109] The covering material can also be a dielectric layer, which carries a charge. The charge type of the dielectric layer is the same as the charge type of the majority carriers in the first doped material layer 110. For example, if the doping type of the first doped material layer 110 is N-, and the electrons in it are the majority carriers, then the dielectric layer can be negatively charged, generating an electric field pointing from the first doped material layer 110 to the dielectric layer. Therefore, under the influence of the electric field generated by the charged dielectric layer, electrons in the first doped material layer 110 located at the edge move towards the center of the first doped material layer 110. Meanwhile, the electric field generated by the first doped structure causes electrons to move away from the first doped structure, so the electrons eventually accumulate between the first doped structure and the dielectric layer.

[0110] In actual operation, the covering material can also simultaneously include the fourth doped structure and the dielectric layer, wherein the dielectric layer can be located outside the fourth doped structure, and the dielectric layer can also be located in the same layer as the fourth doped structure and be in contact with the fourth doped structure, for example, the first material 1411 located on the surface of the first doped material layer 110 away from the second doped structure 120 is the fourth doped structure, the third material 1413 located on the surface of the first doped material layer 110 provided with the second doped structure 120, and the second material 1412 located on the sidewall of the first doped material layer 110 is the dielectric layer, or the first material 1411 and the second material 1412 are the dielectric layer, and the third material 1413 is the third doped structure.

[0111] The covering material can surround the first doped material layer 110, and the setting position can be on the surface of the first doped material layer 110. When a plurality of light detection unit arrays are distributed, the first doped material layer 110 in the single photon avalanche diode is also arrayed. The first doped material layer 110 in different single photon avalanche diodes can be separated by a longitudinal isolation trench. The covering material is located on the surface of the first doped material layer, and thus is adjacent to the isolation trench. At this time, the covering material can be formed on the inner sidewall of the isolation trench 140 or can surround the isolation trench 140. That is, the fourth doped structure and / or the dielectric layer can form the inner sidewall of the isolation trench 140 or can be formed on the periphery of the isolation trench 140.

[0112] For example, in the isolation trench 140, a dielectric layer can be formed on the sidewall, and then a metal filler 142 is used to fill the isolation trench 140, so that the isolation of different single photon avalanche diodes can also be achieved. The dielectric layer here is a charged dielectric layer formed on the sidewall of the first doped material layer 110. The charged dielectric layer can also provide an electric field for moving the multiple carriers in the first doped material layer 110 from the edge to the center. When the charged dielectric layer is formed on the sidewall of the isolation trench 140, it can serve as the covering material or can jointly constitute the covering material with the fourth doped structure.

[0113] The first doped material layer 110 can be connected to the first lead-out end 143 through the covering material. Therefore, in actual operation, the first lead-out end 143 and the second lead-out end (i.e., the second doped structure 120) can be arranged on the same layer, so as to facilitate the application of a bias voltage to both. The first lead-out end 143 can be a doped material, and the doping type thereof is different from that of the second doped structure 120. The doping of the first lead-out end 143 is also heavy doping, which can be represented by P+ or N+. The first lead-out end 143 and the second lead-out end can also be connected to an interconnection line 133. The interconnection line 133 can be a metal material. In the case where light irradiates the single photon avalanche diode from the side provided with the interconnection line 133, the interconnection line 133 can be a transparent electrode material, so as to improve the light transmittance. The interconnection line 133 can be arranged in a covering layer 134, as shown in FIG. 1B. Figure 11 The first doped material layer 110 can be connected to the first lead-out end 143 through the covering material. Therefore, in actual operation, the first lead-out end 143 and the second lead-out end (i.e., the second doped structure 120) can be arranged on the same layer, so as to facilitate the application of a bias voltage to both. The first lead-out end 143 can be a doped material, and the doping type thereof is different from that of the second doped structure 120. The doping of the first lead-out end 143 is also heavy doping, which can be represented by P+ or N+. The first lead-out end 143 and the second lead-out end can also be connected to an interconnection line 133. The interconnection line 133 can be a metal material. In the case where light irradiates the single photon avalanche diode from the side provided with the interconnection line 133, the interconnection line 133 can be a transparent electrode material, so as to improve the light transmittance. The interconnection line 133 can be arranged in a covering layer 134, as shown in FIG. 1B.

[0114] When the covering material is located on the sidewall of the second doped structure 120, because the covering material tends to have opposite type of carriers with the second doped structure 120, the contact surface of the two has a large potential difference, at this time, the third doped structure 121 is formed between the second doped structure 120 and the covering material, which can reduce the potential gradient of the horizontal surface where the second doped structure 120 and the first doped structure are located, and reduce the leakage.

[0115] Therefore, in the embodiment of the present application, the single photon avalanche diode can further include the third doped structure 121, the doping type of the third doped structure 121 is consistent with the second doped structure 120, and the doping concentration is lower than that of the second doped structure 120. When the second part 112 of the first doped structure is located on the part of the sidewall of the second doped structure 120 close to the first doped material layer 110, the third doped structure 121 can be located on the part of the sidewall of the second doped structure 120 not covered by the first doped structure, at this time, the second doped structure 120 and the first doped structure can be directly contacted, for another structure of the single photon avalanche diode provided by the embodiment of the present application, please refer to FIG. 6. Figure 8 The third doped structure 121 can reduce the potential gradient of the horizontal surface where the second doped structure 120 and the first doped structure are located, the third doped structure 121 can also be located between the second doped structure 120 and the first doped structure, as a breakdown protection layer between the second doped structure 120 and the first doped structure, of course, the third doped structure 121 can be located on the part of the sidewall of the second doped structure 120 not covered by the first doped structure, and between the second doped structure 120 and the first doped structure, that is, the third doped structure 121 can cover the entire sidewall of the second doped structure 120, and the horizontal surface of the second doped structure 120 close to the first doped material layer 110, please refer to FIG. 7. Figure 4

[0116] That is, the third doped structure 121 can be located on the sidewall of the second doped structure 120, or can be located on the sidewall of the second doped structure 120 and between the second doped structure 120 and the first doped structure, at this time, the existence of the third doped structure 121 will not affect the avalanche region position and avalanche probability between the second doped structure 120 and the first doped structure, and the avalanche region is still located at the corner position adjacent to the first doped structure and the second doped structure.

[0117] ​The lateral thickness of the third doped structure 121 on the sidewall of the second doped structure 120 can be determined according to actual conditions. When the third doped structure 121 is located on the sidewall of the part of the second doped structure 120 not covered by the first doped structure, the lateral thickness of the third doped structure 121 can be appropriately increased, so as to effectively reduce the potential gradient of the horizontal surface where the second doped structure 120 and the first doped structure are located.

[0118] The cross section of the first doped material layer 110 can be polygonal, for example, rectangular, triangular, hexagonal, etc. The second doped structure 120 can be located in the middle of the first doped material layer 110, or can be arranged along the edge of the first doped material layer, or can be located at the top corner of the first doped material layer. Referring to Figure 4 As shown in the figure, the second doped structure 120 is located in the middle of the first doped material layer 110, referring to Figure 9 and Figure 10 As shown in the figure, the second doped structure 120 can be arranged at the top corner of the first doped material layer, wherein Figure 9 is a structure diagram of another single photon avalanche diode in the embodiments of the present application, Figure 10 is a structure diagram of another single photon avalanche diode in the embodiments of the present application, Figure 9 is a projection diagram of each component in the horizontal plane, specifically, the second doped structure and the first doped structure can be located at the upper right corner of the first doped material layer, the isolation trench 140 separates different first doped material layers, the covering material is formed outside the isolation trench and is connected with the first lead 143, the cross section of the second doped structure 120 is a quarter circle, the third doped structure 121 and the first doped structure are a quarter circular ring, in this way, the electric field generated by the covering material makes the photo-generated carriers in the first doped material layer 110 move from the edge to the center, and the electric field between the second doped structure 120, the third doped structure 121, the first doped structure and the first doped material layer 110 makes the photo-generated carriers move towards the second doped structure 120 and form avalanche current.

[0119] Of course, the second doped structure 120 can also be arranged along one side of the rectangular first doped material layer, at this time, the second doped structure 120 can be a half circle, and the third doped structure 121 and the first doped structure are a half circular ring, which will not be exemplified here.

[0120] In the embodiments of the present application, the first doped material layers located in different light detection units can be separated by the isolation trench, at this time, a bias voltage can also be applied to the metal filling layer 142 in the isolation trench 140, so as to accelerate the collection of photo-generated carriers. Specifically, when the doping type of the first doped material layer 110 is N-, a negative bias voltage can be applied to the metal filling layer 142, and when the doping type of the first doped material layer 110 is P-, a positive bias voltage can be applied to the metal filling layer 142.

[0121] In the embodiment of the present application, the single photon avalanche diode can further include a substrate 100, and the second doped structure 120, the first doped structure and the first doped material layer 110 described above can be arranged on the substrate 100. Since the light detection device is divided into front-illuminated (FSI) and back-illuminated (BSI) two forms, the stacking manner on the substrate 100 is also different. Generally, the light detection device can include a single photon avalanche diode and a logic circuit layer. In the front-illuminated device, the logic circuit layer can be located at the same layer as the single photon avalanche diode, light directly irradiates the single photon avalanche diode from above, and the logic circuit layer does not affect the shielding of the light beam. In the back-illuminated device, the logic circuit layer is located below the single photon avalanche diode, light directly irradiates the single photon avalanche diode, and the logic circuit layer also does not shield the light beam.

[0122] Specifically, referring to FIG. 1A and FIG. 1B, FIG. 1A and FIG. 1B are structural schematic diagrams of another single photon avalanche diode provided by the embodiment of the present application. In the front-illuminated device, referring to FIG. 1A, in order to facilitate connection, the second doped structure 120 of the single photon avalanche diode can be arranged upward, and the interconnection layer 133 can be arranged below the second doped structure 120, for realizing the interconnection of the single photon avalanche diode and the logic circuit layer. The interconnection layer 133 can be arranged in the dielectric layer 134. Light is incident on the first doped material layer 110 from top to bottom, without needing to pass through the substrate 100. That is, the first doped material layer 110, the first doped structure and the second doped structure 120 can be arranged on the substrate 100 from bottom to top. At this time, the interconnection layer 133 on the second doped structure 120 can be a transparent metal material, so as to reduce the absorption of light. Figure 11 Figure 11 A, in order to facilitate connection, the second doped structure 120 of the single photon avalanche diode can be arranged upward, and the interconnection layer 133 can be arranged below the second doped structure 120, for realizing the interconnection of the single photon avalanche diode and the logic circuit layer. The interconnection layer 133 can be arranged in the dielectric layer 134. Light is incident on the first doped material layer 110 from top to bottom, without needing to pass through the substrate 100. That is, the first doped material layer 110, the first doped structure and the second doped structure 120 can be arranged on the substrate 100 from bottom to top. At this time, the interconnection layer 133 on the second doped structure 120 can be a transparent metal material, so as to reduce the absorption of light.

[0123] In the back-illuminated device, referring to FIG. 1B, in order to facilitate connection, the second doped structure 120 of the single photon avalanche diode can be arranged downward, and the interconnection layer 133 can be arranged below the second doped structure 120, for realizing the interconnection of the single photon avalanche diode and the logic circuit layer. The interconnection layer 133 can be arranged in the dielectric layer 134. Light is directly incident on the first doped material layer 110 from top to bottom, without needing to pass through the substrate 100. That is, the second doped structure 120, the first doped structure and the first doped material layer 110 can be arranged on the substrate 100 from bottom to top. Figure 11

[0124] ​​The substrate 100 can be an insulating substrate or a semiconductor substrate. When the substrate 100 is a semiconductor substrate, the surface of the substrate 100 can be formed with an insulating layer, so as to isolate the substrate 100 and other film layers thereon, and avoid the influence of the carrier avalanche current generated by the substrate 100, thereby reducing the dark count. For example, the substrate 100 is an insulator, and the second doped structure 120, the first doped structure, and the third doped structure 121 are doped silicon materials, thereby forming a silicon on insulator (SOI) structure.

[0125] In the single photon avalanche diode in the embodiment of the present application, a microlens layer 150 can also be included, which can be located on the side surface away from the substrate 100. The microlens layer 150 can be used to focus the light signal, so as to concentrate the light signal at a position where the avalanche effect is easy to occur. For example, the microlens layer 150 can be located on the side surface of the second doped structure 120. Figure 12 As shown in FIG. 3, which is a structural schematic diagram of another single photon avalanche diode provided in the embodiment of the present application. Figure 12 A is a front-illuminated structure, and the microlens layer 150 is arranged on the second doped structure 120. Figure 12 B is a back-illuminated structure, and the microlens layer 150 is arranged on the first doped material layer 110. Figure 11 In the embodiment, the substrate 100 is an insulating substrate.

[0126] Specifically, the focusing position of the microlens layer 150 is in the middle between the edge of the first doped material layer 110 and the second doped structure 120, so as to focus the light beam to the position between the first doped structure and the edge of the first doped material layer 110, and improve the carrier collection efficiency.

[0127] Specifically, the microlens layer can include array-arranged microlenses, which can be convex lenses and / or Fresnel lenses. The Fresnel lenses can have a consistent focusing effect as the convex lenses, and have a smaller longitudinal size, which is beneficial to reduce the size of the device. The arrangement position of the microlenses can be determined according to the shape of the second doped structure 120, and the arrangement number of the microlenses can be determined according to the actual situation. An anti-reflection layer can also be arranged on the microlens layer, so as to increase the quantum efficiency of the target light.

[0128] In the embodiments of the present application, the single-photon avalanche diode can further include an inverted pyramid structure 151, which can be an inverted pyramid array (IPA), and the inverted pyramid structure 151 is located on the side away from the substrate 100, and is used to refract light when the light passes through, so as to change the transmission direction of the light, so that the light is not only transmitted in the vertical direction in the first doped material layer 110, thereby increasing the transmission path of the light and increasing the possibility of the first doped material layer 110 absorbing the light to generate carriers. The structure in the inverted pyramid structure 151 has multiple planes that are not parallel to the surface of the substrate, and the refractive index of the inverted pyramid structure can be different from the refractive index of the film layer above or below it, so that the light is refracted when the light passes through, thereby changing the transmission direction of the light. Specifically, the inverted pyramid structure can be obtained by etching the first doped material layer and filling, or can be obtained by etching the covering material and filling.

[0129] The inverted pyramid structure 151 can be located between the microlens layer 150 and the film layer below it, so that the light is refracted after being focused, for example, between the microlens layer 150 and the third material 1413 on the side wall of the second doped structure 120, and the inverted pyramid structure 151 can be obtained by etching the third material 1413 below it and filling, and a flat layer 152 can be arranged on the inverted pyramid structure 151, which is beneficial to the formation of the film layer thereon, and reference is made to Figure 12 A, or the inverted pyramid structure 151 can be located between the microlens layer 150 and the first doped material layer 110, and the inverted pyramid structure 151 can be obtained by etching the first material 1411 below it and filling, and a flat layer 152 can be further formed on the inverted pyramid structure 151, and reference is made to Figure 12 B.

[0130] It should be noted that in the embodiments of the present application, the inverted pyramid structure 151 is located in the covering material, and if the covering material is a charged dielectric layer, the first doped material layer 110 can be etched first to obtain the inverted pyramid structure, and then the charged dielectric layer is formed on the inverted pyramid structure, so that the first doped material layer 110 can not be doped to form the fourth doped structure.

[0131] The single-photon avalanche diode provided by the embodiment of the present application comprises a first doped material layer, a second doped structure, a first doped structure and a covering material, wherein the first doped material layer and the second doped structure are stacked in the longitudinal direction, the cross section of the second doped structure is smaller than that of the first doped material layer, the doping types of the first doped material layer and the second doped structure are consistent, the doping concentration of the second doped structure is higher than that of the first doped material layer, the first doped structure is located between the second doped structure and the first doped material layer and covers the sidewall of the second doped structure, the doping type of the first doped structure is opposite to that of the second doped structure, and the region adjacent to the first doped structure and the second doped structure is used to form an avalanche region, and the covering material is formed on the surface of the first doped material layer and is used to provide an electric field for moving the multiple carriers in the first doped material layer from the edge to the center.

[0132] That is, in the embodiment of the present application, the first doped structure is formed on the horizontal surface and the sidewall of the second doped structure, the region adjacent to the first doped structure and the second doped structure is used to form an avalanche region, and the high-field region of the corner region adjacent to the second doped structure and the first doped structure is more likely to form an avalanche region, that is, the avalanche effect occurs in the edge region of the second doped structure and the first doped structure, so that the probability of generating the avalanche effect is relatively high, and the covering material can provide an electric field for moving the multiple carriers in the first doped material layer from the edge to the center, thereby facilitating the movement of the photo-generated carriers in the first doped material layer to the avalanche region, so that the charge collection efficiency is improved to a certain extent, and therefore the device has a relatively high quantum efficiency, so that the device can have a relatively high light detection efficiency.

[0133] Based on the single-photon avalanche diode provided in the above embodiment, the embodiment of the present application further provides a manufacturing method of a single-photon avalanche diode. Figure 13 As shown in FIG. 1, the flowchart of the manufacturing method of the single-photon avalanche diode provided by the embodiment of the present application, specifically, the method can comprise the following steps:

[0134] S101, providing a substrate.

[0135] The substrate can be an insulating substrate or a semiconductor substrate, when the substrate is a semiconductor substrate, an insulating layer can be formed on the surface of the substrate, so as to isolate the substrate and other film layers thereon, thereby avoiding the influence of the carrier avalanche current generated by the substrate, and thus the dark count can be reduced.

[0136] S102, sequentially forming a second doped structure, a first doped structure and a first doped material layer from bottom to top on the substrate; or, sequentially forming a first doped material layer, a first doped structure and a second doped structure from bottom to top on the substrate.

[0137] The cross-section of the second doped structure is smaller than that of the first doped material layer. The doping types of the first doped material layer and the second doped structure are the same, and the doping concentration of the second doped structure is higher than that of the first doped material layer. The first doped structure is located between the second doped structure and the first doped material layer and covers the sidewall of the second doped structure. The doping type of the first doped structure is opposite to that of the second doped structure. The region adjacent to the first doped structure and the second doped structure is used to form an avalanche region. A covering material is formed on the surface of the first doped material layer to provide an electric field that causes majority carriers in the first doped material layer to move from the edge to the center.

[0138] The first doped material layer, the first doped structure, and the second doped structure can be doped silicon materials.

[0139] In one possible implementation, a second doped structure, a first doped structure, and a first doped material layer can be formed sequentially from bottom to top on a substrate. Then, an interconnect layer for interconnection with the logic circuit layer, and a logic circuit located on the same layer as the single-photon avalanche diode, can be formed on the second doped structure to form a photodetector unit. Alternatively, the logic circuit can be formed before the single-photon avalanche diode.

[0140] Specifically, a bulk structure can be formed on a substrate, and a first doped material layer, a third doped material, and a second doped structure can be sequentially doped within the bulk structure. The bulk structure can be an intrinsic layer or a lightly doped layer. The lightly doped layer can be the bulk structure of the first doped material layer. By doping within the bulk structure of the first doped material layer, the first doped structure and the second doped structure are formed. The lightly doped layer can also be other material layers, and the first doped material layer, the first doped structure, and the second doped structure are obtained through doping. Alternatively, the first doped material layer, the third doped material, and the second doped structure can be sequentially formed on the substrate via epitaxial growth.

[0141] For example, refer to Figure 11 In the single-photon avalanche diode shown in Figure A, a bulk structure of a first doped material layer 110 can first be formed on a substrate. The bulk structure includes the positions of the first doped structure, the second doped structure 120, and the cover material. Then, the bottom of the bulk structure can be de-doped to obtain a first material 1411 in the cover material located on the bottom surface of the first doped material layer 110. Next, the sidewalls of the bulk structure can be de-doped to obtain a second material 1412 in the cover material located on the sidewalls of the first doped material layer 110. Then, the middle of the bulk structure can be de-doped to obtain a first portion 111 and a second portion 112 of the first doped structure. Finally, the upper part of the bulk structure can be doped to form a second doped structure 130, and then de-doped to form a third material 1413 in the cover material.

[0142] As another possible implementation, a second doped structure, a first doped structure, and a first doped material layer can be formed sequentially from bottom to top on a substrate. In this case, a logic circuit layer and a dielectric layer covering the logic circuit layer may already be formed on the substrate, and the second doped structure can be formed on top of the dielectric layer covering the logic circuit layer. Before forming the second doped structure, an interconnect layer interconnecting the logic circuit layer can also be formed, and the interconnect layer connects the second doped structure and the logic circuit layer.

[0143] Specifically, a bulk structure can be formed on a substrate, and a second doped structure, a first doped structure, and a first doped material layer can be sequentially doped within the bulk structure. The bulk structure can be an intrinsic layer or a lightly doped layer. The lightly doped layer can be the first doped material layer, and the first doped structure and the second doped structure are formed by doping within the first doped material layer. The lightly doped layer can also be other material layers, and the first doped material layer, the first doped structure, and the second doped structure are obtained through doping. Alternatively, the second doped structure, the first doped structure, and the first doped material layer can be sequentially formed on the substrate via epitaxial growth.

[0144] For example, refer to Figure 11 In the single-photon avalanche diode shown in B, a bulk structure of a first doped material layer 110 can first be formed on a substrate. The location of this bulk structure includes the first doped structure, the second doped structure 120, and the position of the cover material. Then, heavy doping can be performed at the bottom of the bulk structure to form the second doped structure 120, and dedoping can be performed to form the third material 1413 in the cover material. Next, dedoping can be performed in the middle of the bulk structure to obtain the first part 111 and the second part 112 of the first doped structure, and dedoping can be performed on the sidewalls of the bulk structure to obtain the second material 1412 in the cover material located on the sidewalls of the first doped material layer 110. Finally, dedoping can be performed on the upper part of the bulk structure to obtain the first material 1411 in the cover material located on the bottom surface of the first doped material layer 110.

[0145] In this embodiment, the single-photon avalanche diode may further include a capping material formed on the surface of the first doped material layer. Specifically, the capping material may be formed on the surface of the first doped material layer away from the second doped structure, and / or on the sidewalls of the first doped material layer, and / or on the sidewalls of the second doped material. The capping material may also provide an electric field that causes majority carriers in the first doped material layer to move from the edge to the center. Therefore, the capping material can promote the movement of charge carriers from the edge to the center, thereby improving charge collection efficiency. The first doped material layer may be connected to a first lead using the capping material, thereby applying a bias voltage to the single-photon avalanche diode.

[0146] The covering material can be a fourth doped structure, wherein the doping type of the fourth doped structure is opposite to the doping type of the first doped material layer. For example, the doping type of the first doped material layer is N-, and the doping type of the fourth doped structure can be P. At this time, the electric field direction is from the first doped material layer to the fourth doped structure. Therefore, the electrons in the first doped material layer are multi-electrons, and the electrons at the edge move to the middle of the first doped material layer under the action of the electric field generated by the fourth doped structure. The doping type of the first doped structure is opposite to the doping type of the first doped material layer. For example, when the doping type of the first doped material layer is N-, the doping type of the first doped structure can also be P. At this time, the electric field direction is from the first doped material layer to the first doped structure. The electrons around the first doped structure move away from the first doped structure under the action of the electric field. Therefore, the final electrons will gather between the first doped structure and the fourth doped structure.

[0147] The covering material can also be a dielectric layer. The dielectric layer has a charge, and the charge type of the dielectric layer is the same as the charge type of the multi-electrons in the first doped material layer. For example, the doping type of the first doped material layer is N-, and the electrons in the first doped material layer are multi-electrons. Therefore, the dielectric layer can be negatively charged, and an electric field is generated from the first doped material layer to the dielectric layer. Therefore, the electrons in the first doped material layer at the edge move to the middle of the first doped material layer under the action of the electric field generated by the charged dielectric layer. The electric field generated by the first doped structure promotes the electrons to move away from the first doped structure. Therefore, the final electrons will gather between the first doped structure and the dielectric layer.

[0148] In actual operation, the covering material can also include a fourth doped structure and a dielectric layer. The dielectric layer can be located outside the fourth doped structure, or the charged dielectric layer can be located in the same layer as the fourth doped structure and be connected to the fourth doped structure. For example, the first material 1411 located on the surface of the first doped material layer 110 away from the second doped structure 120 is a fourth doped structure, the third material 1413 located on the surface of the first doped material layer 110 provided with the second doped structure 120, and the second material 1412 located on the sidewall of the first doped material layer 110 is a dielectric layer. Alternatively, the first material 1411 and the second material 1412 are dielectric layers, and the third material 1413 is a third doped structure.

[0149] The covering material can surround the first doped material layer, and is arranged on the surface of the first doped material layer. When the plurality of photodetection unit arrays are arranged, the first doped material layer in the single photon avalanche diode is also arranged in an array. The first doped material layers in different single photon avalanche diodes can be separated by longitudinal isolation trenches. The covering material is located on the surface of the first doped material layer, and is adjacent to the isolation trenches. At this time, the covering material can be formed on the inner sidewall of the isolation trench, or can surround the isolation trench. That is, the fourth doped structure and / or the charged dielectric layer can form the inner sidewall of the isolation trench, or can be formed on the periphery of the isolation trench.

[0150] The covering material can be formed by doping or epitaxial growth. For example, doping can be performed on the edge of the first doped material layer to obtain a fourth doped structure surrounding the remaining first doped material layer, or etching can be performed on the first doped material layer to form an isolation trench, and a charged dielectric layer can be formed on the sidewall of the isolation trench by epitaxial growth.

[0151] In the embodiments of the present application, a third doped structure can also be formed. The third doped structure 121 has the same doping type as the second doped structure 120, and has a doping concentration lower than that of the second doped structure 120. When the second part 112 of the first doped structure is located on the part of the sidewall of the second doped structure 120 close to the first doped material layer 110, the third doped structure 121 can be located on the part of the sidewall of the second doped structure 120 not covered by the first doped structure. At this time, the second doped structure 120 and the first doped structure can be directly in contact, and the presence of the third doped structure 121 can reduce the potential gradient of the horizontal surface where the second doped structure 120 and the first doped structure are located. The third doped structure 121 can also be located between the second doped structure 120 and the first doped structure, as a breakdown protection layer between the second doped structure 120 and the first doped structure. Of course, the third doped structure 121 can be located on the part of the sidewall of the second doped structure 120 not covered by the first doped structure, and between the second doped structure 120 and the first doped structure, that is, the third doped structure 121 can cover the entire sidewall of the second doped structure 120 and the horizontal surface of the second doped structure 120 close to the first doped material layer 110.

[0152] That is, the third doped structure 121 can be located on the sidewall of the second doped structure 120, or can be located on the sidewall of the second doped structure 120 and between the second doped structure 120 and the first doped structure. At this time, the presence of the third doped structure 121 will not affect the position of the avalanche region and the avalanche probability between the second doped structure 120 and the first doped structure.

[0153] In the embodiments of the present application, a microlens layer can also be formed, which can be located on the side surface away from the substrate. The microlens layer can be used to focus the light signal, so that the light signal is concentrated in a position where avalanche effect is easy to occur. Specifically, the focusing position of the microlens layer overlaps with the projection of the second doped structure on the horizontal plane, so that the light beam can be focused on the position directly opposite to the second doped structure, thereby improving the carrier collection efficiency. Specifically, the microlens layer can include arrayed microlenses, which can be convex lenses and / or Fresnel lenses.

[0154] The microlens layer can be formed by reflowing, etching back, etc. Specifically, in the reflowing, a photosensitive organic material is spin-coated on the side surface of the device away from the substrate, and then the microlens layer of the photosensitive organic material can be obtained by exposure, development and heating reflow. In the etching back, a planar layer is deposited on the side surface of the device away from the substrate, a photosensitive organic material is spin-coated on the planar layer, and then a mask layer of the photosensitive organic material is obtained by exposure, development and heating reflow. Then, an etching process can be performed to transfer the pattern on the photosensitive organic material to the planar layer.

[0155] In the embodiments of the present application, an inverted pyramid structure can also be formed, which can be an array of inverted pyramid structures and located on the side away from the substrate. The inverted pyramid structure is used to refract the light when it passes through, so as to change the transmission direction of the light. In this way, the light in the first doped material layer is transmitted not only in the vertical direction, thereby increasing the transmission path of the light and increasing the possibility of the first doped material layer absorbing the light to generate carriers. The inverted pyramid structure can be located between the microlens layer and the film layer below, so that the light is refracted after being focused. Therefore, the inverted pyramid structure can be formed before the microlens layer is formed.

[0156] The embodiments of the present application provide a manufacturing method of a single-photon avalanche diode. Specifically, a second doped structure, a first doped structure and a third doped structure can be sequentially formed from bottom to top on a substrate, or a third doped structure, a first doped structure and a second doped structure can be sequentially formed from bottom to top on the right side of the substrate. The cross section of the second doped structure is smaller than the first doped material layer. The doping type of the first doped material layer and the second doped structure is consistent, and the doping concentration of the second doped structure is higher than that of the first doped material layer. The first doped structure is located between the second doped structure and the first doped material layer, and covers the sidewall of the second doped structure. The doping type of the first doped structure is opposite to that of the second doped structure, and the adjacent region thereof is used to form an avalanche region. The surface of the first doped material layer is formed with a covering material, which is used to provide an electric field for moving the multiple carriers in the first doped material layer from the edge to the center.

[0157] That is, in the embodiments of the present application, the first doped structure is formed on the horizontal surface and the sidewall of the second doped structure, and the region adjacent to the second doped structure of the first doped structure is used to form the avalanche region, and the high field region of the corner region adjacent to the second doped structure and the first doped structure is more likely to form the avalanche region, that is, the avalanche effect occurs in the edge region of the second doped structure and the first doped structure, so that the probability of generating the avalanche effect is larger, and the covering material can provide an electric field for the motion of the multi-carriers in the first doped material layer from the edge to the center, which is beneficial to the movement of the photo-generated carriers in the first doped material layer to the avalanche region, so that the charge collection efficiency is improved to a certain extent, and therefore the device has a higher quantum efficiency, so that the device can have a higher light detection efficiency.

[0158] Each of the embodiments in the specification is described in a progressive manner, and the same and similar parts between the embodiments can be referred to each other, and each embodiment mainly describes the difference from other embodiments. In particular, for the method embodiments, since they are basically similar to the structural embodiments, they are described more simply, and the related parts can be referred to the part of the structural embodiments.

[0159] The above is a specific implementation of the present application. It should be understood that the above-described embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for some technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A single-photon avalanche diode, characterized in that, It includes a first doped material layer, a second doped structure, a first doped structure, and a covering material; The first doped material layer and the second doped structure are stacked vertically, and the cross-section of the second doped structure is smaller than that of the first doped material layer; the first doped material layer and the second doped structure have the same doping type, and the doping concentration of the second doped structure is higher than that of the first doped material layer; The first doped structure covers the surface of the second doped structure facing the first doped material layer and also covers the sidewalls of the second doped structure; the doping type of the first doped structure is opposite to that of the second doped structure, and the region adjacent to the first doped structure and the second doped structure is used to form an avalanche region; The covering material covers the surface of the first doped material layer and provides an electric field that causes majority carriers in the first doped material layer to move from the edge to the center.

2. The single-photon avalanche diode according to claim 1, characterized in that, It also includes a third doped structure; When the first doped structure covers a portion of the sidewall of the second doped structure near the first doped material layer, the third doped structure is located on a portion of the sidewall of the second doped structure not covered by the first doped structure, or the third doped structure is located between the second doped structure and the first doped structure, and on a portion of the sidewall of the second doped structure not covered by the first doped structure. The doping type of the third doped structure is the same as that of the second doped structure, but the doping concentration is lower than that of the second doped structure.

3. The single-photon avalanche diode according to claim 1, characterized in that, The first doped structure extends longitudinally through the first doped material layer.

4. The single-photon avalanche diode according to claim 1, characterized in that, The covering material is a fourth doped structure and / or a dielectric layer, wherein the dielectric layer carries a charge; the doping type of the fourth doped structure is opposite to that of the first doped material layer, and the charge type of the dielectric layer is the same as that of the majority carriers in the first doped material layer.

5. The single-photon avalanche diode according to claim 1, characterized in that, The covering material is connected to the first lead-out terminal, and the first lead-out terminal and the second doped structure are used to connect to different bias voltages respectively.

6. The single-photon avalanche diode according to claim 1, characterized in that, The second doped structure is located in the middle of the first doped material layer, or the second doped structure is disposed along the edge of the first doped material layer, or the second doped structure is located at the top corner of the first doped material layer.

7. The single-photon avalanche diode according to any one of claims 1-6, characterized in that, It also includes the substrate; A first doped material layer and a second doped structure are sequentially disposed on the substrate from bottom to top; Alternatively, a second doped structure and a first doped material layer may be disposed on the substrate from bottom to top.

8. The single-photon avalanche diode according to claim 7, characterized in that, It also includes a microlens layer; The microlens layer is located on the side surface away from the substrate; the microlens layer is focused between the edge of the first doped material layer and the second doped structure.

9. The single-photon avalanche diode according to claim 8, characterized in that, The microlens layer consists of an array of microlenses, including convex lenses and / or Fresnel lenses.

10. The single-photon avalanche diode according to claim 7, characterized in that, It also includes an inverted pyramid structure; the inverted pyramid structure is located on the side away from the substrate.

11. A method for manufacturing a single-photon avalanche diode, characterized in that, include: Provide substrate; A second doped structure, a first doped structure, and a first doped material layer are formed sequentially from bottom to top on the substrate; Alternatively, a first doped material layer, a first doped structure, and a second doped structure may be formed sequentially from bottom to top on the substrate; Wherein, the cross-section of the second doped structure is smaller than that of the first doped material layer; the doping types of the first doped material layer and the second doped structure are the same, and the doping concentration of the second doped structure is higher than that of the first doped material layer; The first doped structure covers the surface of the second doped structure facing the first doped material layer and also covers the sidewalls of the second doped structure; the doping type of the first doped structure is opposite to that of the second doped structure, and the region adjacent to the first doped structure and the second doped structure is used to form an avalanche region; a covering material is formed on the surface of the first doped material layer to provide an electric field that causes majority carriers in the first doped material layer to move from the edge to the center.

12. The method according to claim 11, characterized in that, Also includes: Formation of a third doped structure; When the first doped structure covers a portion of the sidewall of the second doped structure near the first doped material layer, the third doped structure is located on a portion of the sidewall of the second doped structure not covered by the first doped structure, or the third doped structure is located between the second doped structure and the first doped structure, and on a portion of the sidewall of the second doped structure not covered by the first doped structure. The doping type of the third doped structure is the same as that of the second doped structure, but the doping concentration is lower than that of the second doped structure.

13. The method according to claim 11, characterized in that, The first doped structure extends longitudinally through the first doped material layer.

14. The method according to claim 11, characterized in that, The second doped structure is located in the middle of the first doped material layer, or the second doped structure is disposed along the edge of the first doped material layer, or the second doped structure is located at the top corner of the first doped material layer.

15. A photodetector, characterized in that, It includes multiple optical detection units, each optical detection unit comprising a logic circuit layer and a single-photon avalanche diode as described in any one of claims 1-10; the logic circuit layer is electrically connected to the single-photon avalanche diode.

16. The optical detection device according to claim 15, characterized in that, The single-photon avalanche diodes in different detection units are isolated by isolation trenches.

17. The optical detection device according to claim 16, characterized in that, The isolation trench is filled with insulating material; or the sidewall of the isolation trench has a dielectric layer, and the isolation trench is also filled with a metal filler layer.

18. A light detection system, characterized in that, Includes a light emitting device and a light detection device as described in any one of claims 15-17; The optical emitting device is used to emit optical signals to the object under test; The optical detection device is used to generate an avalanche current based on the light signal reflected by the object under test.

Images