Photoelectric sensor, photoelectric detection device and electronic equipment

Abstract

The utility model provides a photoelectric sensor, a photoelectric detection device and electronic equipment. The photoelectric sensor comprises a diode substrate, a plurality of avalanche pixel units and an isolation structure, wherein the diode substrate is provided with a first surface and a second surface which are opposite in the vertical direction; the avalanche pixel units are arranged in the diode substrate; the isolation structure is used for isolating the avalanche pixel units; the isolation structure comprises a deep groove isolation layer and a shallow groove insulation layer. The avalanche pixel unit comprises a central electrode, an edge electrode, a central doping structure and an edge doping structure. The portion, different from the edge doping structure in doping type, in the center doping structure forms an avalanche region in the vertical direction. The center doping structure and the edge doping structure form a protection ring in the horizontal direction, and the edge doping structure is arranged close to the shallow groove insulation layer and is electrically isolated from the deep groove isolation layer through the shallow groove insulation layer.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductor photoelectric detection, in particular to a photoelectric sensor, a photoelectric detection device and an electronic device. Background Art

[0002] Single-photon avalanche diodes (SPADs) enable rapid detection of single photon signals, offering advantages such as high gain, high speed, and low power consumption, making them a leading single-photon detection device. Photoelectric sensors are widely used in military, civilian, and commercial applications, particularly in near-infrared weak light detection, such as lidar, optical communications, astronomical ranging, and fluorescence imaging.

[0003] As the application of photoelectric sensors becomes more and more extensive, there are increasingly higher requirements for the overall performance of photoelectric sensors. Utility Model Content

[0004] In response to the aforementioned technical problems, the photoelectric sensor, photoelectric detection device, and electronic equipment provided by the present invention can increase the size of the guard ring by optimizing the device structure, thereby improving device performance.

[0005] In a first aspect, the present invention provides a photoelectric sensor, comprising a diode substrate, an isolation structure, and an avalanche pixel unit. The diode substrate has a first surface and a second surface facing each other in a vertical direction. A plurality of avalanche units are disposed within the diode substrate. The isolation structure is used to isolate the avalanche pixel units and comprises a deep trench isolation layer and a shallow trench insulation layer. The shallow trench insulation layer is formed vertically on the deep trench isolation layer and close to the second surface. The distance from the shallow trench insulation layer to the second surface is greater than the electrode formation depth, and the horizontal dimension of the shallow trench insulation layer is no greater than the horizontal dimension of the deep trench isolation layer. The avalanche pixel unit comprises a central electrode, an edge electrode, a central doping structure, and an edge doping structure. The central electrode and the edge electrode are disposed on the second surface. The central doping structure and the edge doping structure extend vertically from the second surface into the interior of the diode substrate and are separated horizontally within the diode substrate. The central doping structure is electrically connected to the central electrode. The edge electrode is disposed on the edge doping structure along the extension direction of the isolation structure. The portion of the central doping structure having a different doping type from that of the edge doping structure forms an avalanche zone along the vertical direction, and a guard ring is formed between the central doping structure and the edge doping structure along the horizontal direction; the edge doping structure is arranged close to the shallow trench insulation layer and is electrically isolated from the deep trench isolation layer by the shallow trench insulation layer.

[0006] In some embodiments, the vertical dimension of the edge doping structure is smaller than the vertical dimension of the shallow trench isolation layer, and the projection of the edge doping structure along the vertical direction at least partially overlaps with the projection of the deep trench isolation layer along the vertical direction.

[0007] In some embodiments, the edge doping structure spans the isolation structure and extends into two adjacent avalanche pixel units, and is electrically connected to the edge electrodes of each of the two adjacent avalanche pixel units; the side of the edge doping structure away from the second surface is isolated from the side of the deep trench isolation layer close to the second surface by the shallow trench insulation layer.

[0008] In some embodiments, the avalanche pixel unit includes multiple central doping structures, wherein the multiple central doping structures form multiple pixel sub-units, and the central doping structures correspond one-to-one to the pixel sub-units and are arranged in the central area of the corresponding pixel sub-units; the edge doping structure is arranged in the pixel sub-unit adjacent to the deep trench isolation layer among the multiple pixel sub-units and is located on the side close to the deep trench isolation layer; a lightly doped structure is arranged in the area away from the deep trench isolation layer between two adjacent pixel sub-units among the multiple pixel sub-units, wherein the lightly doped structure has the same doping type as the edge doping structure.

[0009] In some embodiments, the lightly doped structure in the pixel sub-unit adjacent to the deep trench isolation layer among the plurality of pixel sub-units is not electrically connected to the external electrode.

[0010] In some embodiments, when the pixel edge of the avalanche pixel unit reaches the minimum value D of the shortest distance of the central doping structure emin With the maximum value D emax The width D of the guard ring is not equal to gr Satisfy the following relationship: D emin -W avg <D gr <D emax -W avg , where W avg is the average size of the edge doping structure in the horizontal direction.

[0011] In some embodiments, the width D of the guard ring is gr The doped structure is constant to form an annular edge surrounding the central doped structure.

[0012] In some embodiments, the pixel edge is at D emin parallel to the annular edge, and at D emax The edge electrode is not parallel to the annular edge and forms an edge bend, and the edge electrode is arranged between the edge bend and the annular edge.

[0013] In some embodiments, the pixel space is configured as a rectangle, and the edge is bent into a rectangular right-angle region; the minimum value D of the shortest distance between the pixel edge of the avalanche pixel unit and the central doping structure is emin is the shortest distance between the midpoint of the right angle and the central doping structure; the maximum value D in the shortest distance between the pixel edge of the avalanche pixel unit and the central doping structure emax It is the shortest distance between the right angle of the rectangle and the central doping structure.

[0014] In some embodiments, when the pixel edge of the avalanche pixel unit reaches the shortest distance D of the central doping structure e is a constant value, the width D of the guard ring gr =D e -W avg , W avg is the average size of the edge doping structure in the horizontal direction.

[0015] In a second aspect, multiple embodiments of this specification provide a photoelectric detection device, including a photoelectric sensor as described in any implementation method of the first aspect, and the photoelectric detection device obtains relevant information by sensing the electrical signal generated corresponding to the light signal received by the photoelectric sensor.

[0016] In a third aspect, multiple embodiments of this specification provide an electronic device, including the photoelectric detection device described in the second aspect, and the electronic device is used to perform corresponding functions based on relevant information obtained by sensing electrical signals by the photoelectric detection device.

[0017] To address the technical issue of maintaining a safe distance between the metal-filled deep trench isolation layer and the edge doping structure due to process errors in electrode preparation, the photoelectric sensor, photoelectric detection device, and electronic device provided by the embodiments of the present invention optimize the isolation structure of the pixel unit, forming a shallow trench insulation layer on the metal-filled deep trench isolation layer and making its formation depth greater than the etching depth when preparing the electrode. As a result, even if there are process errors when forming the electrode, the electrode will not connect to the metal filling in the deep trench isolation layer, thereby eliminating the need to form a minimum safe distance between the isolation structure and the edge doping structure, allowing the edge doping structure to be placed close to the edge of the pixel. This increases the size of the guard ring between the center doping structure and the edge doping structure while maintaining the same size of the photoelectric sensor, thereby improving the device performance of the photoelectric converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is a schematic diagram of the functional modules of an electronic device provided in some embodiments of the present invention.

[0020] Figure 2 Schematic diagram of the functional modules of the photoelectric detection device provided in some embodiments of the present invention.

[0021] Figure 3 This is a schematic diagram of the top view of the photoelectric sensor in the related technology of the utility model.

[0022] Figure 4 For the related technology of this utility model Figure 3 Schematic diagram of the cross-sectional structure of the photosensor shown.

[0023] Figure 5 、 Figure 6 This is a schematic diagram of the cross-sectional structure of a photoelectric sensor provided in some embodiments of the present invention.

[0024] Figure 7 Some embodiments of the present invention provide Figure 6 The schematic diagram of the top view structure of the photoelectric sensor shown in FIG.

[0025] Figure 8 This is a schematic diagram of the cross-sectional structure of a photoelectric sensor provided in some embodiments of the present invention.

[0026] Figure 9 Some embodiments of the present invention provide Figure 8 The schematic diagram of the top view of the photoelectric sensor shown in FIG.

[0027] Figure 10 Some embodiments of the present invention provide Figure 5 The schematic diagram of the top view structure of the photoelectric sensor shown in FIG.

[0028] Figures 11 to 14 Schematic diagrams of various top views of photoelectric sensors provided in some embodiments of the present invention.

[0029] Figure 15 This is a schematic diagram of the cross-sectional structure of a photoelectric sensor provided in some embodiments of the present invention.

[0030] Among them, 10, electronic device; 100, photoelectric detection device; 110, processing module; 130, receiving component; 131, receiving optical device; 140, transmitting component; 141, driver; 142, light source; 143, transmitting optical device; 200, photoelectric sensor; 210, diode substrate; 211, first surface; 212, second surface; 220, avalanche pixel unit; 221, central doping structure; 2211, avalanche doping structure; 2212, connecting 222. Edge doping structure; 223. Center electrode; 224. Edge electrode; 225. Avalanche region; 226. Guard ring; 227. Pixel subunit; 228. Lightly doped structure; 229. Isolation trench; 230. Isolation structure; 231. Deep trench isolation layer; 2311. Metal isolation structure; 2312. Insulating sidewall; 232. Shallow trench insulation layer; 240. Light-absorbing hole; 300. Storage medium; 400. Processor; 500. Application module. DETAILED DESCRIPTION

[0031] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, a photoelectric sensor, a photoelectric detection device and an electronic device proposed according to the present invention are described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] The aforementioned and other technical contents, features and effects of the present invention are clearly presented in the following detailed description of the specific embodiments with reference to the accompanying drawings. However, the accompanying drawings are only provided for reference and illustration purposes and are not intended to limit the technical solutions of the present invention.

[0033] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations are intended to cover non-exclusive inclusion, such that an article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the article or device comprising the element.

[0034] In order to improve the performance of the photoelectric sensor and the photoelectric detection device and electronic equipment using the photoelectric sensor, the utility model improves the structure of the photoelectric sensor. The specific solution is as follows:

[0035] A photoelectric sensor includes a diode substrate, a plurality of avalanche pixel units, and an isolation structure. The diode substrate has a first surface and a second surface facing each other in a vertical direction. A plurality of avalanche units are disposed within the diode substrate. The isolation structure is used to isolate the avalanche pixel units and includes a deep trench isolation layer and a shallow trench insulation layer. The shallow trench insulation layer is formed vertically on the deep trench isolation layer and close to the second surface. The distance from the shallow trench insulation layer to the second surface is greater than the electrode formation depth, and the horizontal dimension of the shallow trench insulation layer is no greater than the horizontal dimension of the deep trench isolation layer. The avalanche pixel unit includes a central electrode, an edge electrode, a central doping structure, and an edge doping structure. The central electrode and the edge electrode are disposed on the second surface. The central doping structure and the edge doping structure extend vertically from the second surface into the interior of the diode substrate and are separated horizontally within the diode substrate. The central doping structure is electrically connected to the central electrode. The edge electrode is disposed on the edge doping structure along the extension direction of the isolation structure. A portion of the central doping structure having a different doping type from the edge doping structure forms an avalanche region along the vertical direction, and a guard ring is formed horizontally between the central doping structure and the edge doping structure. The edge doping structure is disposed adjacent to the shallow trench insulation layer and is electrically isolated from the deep trench isolation layer by the shallow trench insulation layer. In some embodiments, the vertical dimension of the edge doping structure is smaller than the vertical dimension of the shallow trench insulation layer, and a vertical projection of the edge doping structure at least partially overlaps with a vertical projection of the deep trench isolation layer.

[0036] In some embodiments, the edge doping structure spans the isolation structure and extends into two adjacent avalanche pixel units, and is electrically connected to the edge electrodes of each of the two adjacent avalanche pixel units; the side of the edge doping structure away from the second surface is isolated from the side of the deep trench isolation layer close to the second surface by the shallow trench insulation layer.

[0037] In some embodiments, the avalanche pixel unit includes multiple central doping structures, wherein the multiple central doping structures form multiple pixel sub-units, and the central doping structures correspond one-to-one to the pixel sub-units and are arranged in the central area of the corresponding pixel sub-units; the edge doping structure is arranged in the pixel sub-unit adjacent to the deep trench isolation layer among the multiple pixel sub-units and is located on the side close to the deep trench isolation layer; a lightly doped structure is arranged in the area away from the deep trench isolation layer between two adjacent pixel sub-units among the multiple pixel sub-units, wherein the lightly doped structure has the same doping type as the edge doping structure.

[0038] In some embodiments, the lightly doped structure in the pixel sub-unit adjacent to the deep trench isolation layer among the plurality of pixel sub-units is not electrically connected to the external electrode.

[0039] In some embodiments, when the pixel edge of the avalanche pixel unit reaches the minimum value D of the shortest distance of the central doping structure emin With the maximum value D emax The width D of the guard ring is not equal to gr Satisfy the following relationship: D emin -W avg <D gr <D emax -W avg , where W avg is the average size of the edge doping structure in the horizontal direction.

[0040] In some embodiments, the width D of the guard ring is gr The doped structure is constant to form an annular edge surrounding the central doped structure.

[0041] In some embodiments, the pixel edge is at D emin parallel to the annular edge, and at D emax The edge electrode is not parallel to the annular edge and forms an edge bend, and the edge electrode is arranged between the edge bend and the annular edge.

[0042] In some embodiments, the pixel space is configured as a rectangle, and the edge is bent into a rectangular right-angle region; the minimum value D of the shortest distance between the pixel edge of the avalanche pixel unit and the central doping structure is emin is the shortest distance between the midpoint of the right angle and the central doping structure; the maximum value D in the shortest distance between the pixel edge of the avalanche pixel unit and the central doping structure emax It is the shortest distance between the right angle of the rectangle and the central doping structure.

[0043] In some embodiments, when the pixel edge of the avalanche pixel unit reaches the shortest distance D of the central doping structure e is a constant value, the width D of the guard ring gr =D e -W avg , W avg is the average size of the edge doping structure in the horizontal direction.

[0044] A photoelectric detection device includes the above-mentioned photoelectric sensor, and the photoelectric detection device obtains relevant information by sensing an electrical signal generated in response to a light signal received by the photoelectric sensor.

[0045] An electronic device comprises the photoelectric detection device described in the second aspect, and is used to perform corresponding functions based on relevant information obtained by sensing electrical signals by the photoelectric detection device.

[0046] Example application scenarios:

[0047] See also Figure 1 . The electronic device 10 includes a photoelectric detection device 100. The photoelectric detection device 100 can detect external objects within a detection range to obtain three-dimensional information of the external objects. The detection range can be defined as the stereoscopic space range in which the photoelectric detection device 100 can effectively perform three-dimensional information detection, and can also be referred to as the field of view of the photoelectric detection device 100. The three-dimensional information is, for example, but not limited to, one or more of the proximity information of the external object, the depth information of the surface of the external object, the distance information of the external object, and the spatial coordinate information of the external object.

[0048] The electronic device 10 may include an application module 500, which is configured to perform preset operations or implement corresponding functions based on the detection results of the photoelectric detection device 100. For example, but not limited to: it can determine whether an external object appears within a preset detection range in front of the electronic device 10 based on the proximity information of the external object; or it can control the movement of the electronic device 10 to avoid obstacles based on the distance information of the external object; or it can implement 3D modeling, face recognition, machine vision, etc. based on the depth information of the surface of the external object. The electronic device 10 may also include a storage medium 300, which can support the storage needs of the photoelectric detection device 100 during operation, and one or more processors 400 execute to control related components to implement corresponding functions.

[0049] Optionally, in some embodiments, the photoelectric detection device 100 may be a direct time of flight (dToF) measurement device for performing three-dimensional information sensing based on the direct time of flight (dToF) principle.

[0050] In other embodiments, the photoelectric detection device 100 may also be an indirect time of flight (iToF) measurement device that performs three-dimensional information sensing based on the indirect time of flight (iToF) measurement principle. The iToF measurement device obtains three-dimensional information of an external object by comparing the phase difference between the sensing light beam when it is emitted and when it is reflected and received.

[0051] In the following embodiments of the present invention, the photoelectric detection device 100 is mainly used as an example for distance measurement.

[0052] See also Figure 2The photoelectric detection device 100 may include a transmitting component 140, a receiving component 130, and a processing module 110. The transmitting component 140 includes a driver 141, a light source 142, and a transmitting optical device 143. The processing module 110 may be coupled to a processor of an electronic device, and the transmitting component 140 and the receiving component 130 are respectively coupled to the processing module 110.

[0053] The transmitting component 140 is configured to transmit a sensing light signal into the measurement scene to perform three-dimensional detection of external objects within the measurement scene. Part of the sensing light signal is reflected by the external objects in the measurement scene and returned, carrying three-dimensional information about the external objects. Part of the reflected sensing light signal can be sensed by the receiving component 130 to obtain the three-dimensional information about the external objects.

[0054] The receiving component 130 is configured to sense light signals from the measurement scene and output corresponding light sensing signals. By analyzing the light sensing signals, the distance to external objects within the measurement scene can be detected. It will be appreciated that the light signals sensed by the receiving component 130 may be photons. For example, the photons sensed by the receiving component 130 may include photons of the sensing light signal reflected from external objects in the measurement scene, as well as photons of ambient light in the measurement scene. The processing module 110 is configured to analyze and process the light sensing signals to determine the time when the sensing light signal was sensed by the receiving component 130, and to obtain three-dimensional information about the external object based on the time difference between the time when the sensing light signal was emitted and the time when it was reflected and sensed.

[0055] The receiving component 130 may include a photosensor 200 and a receiving optical device 131. Optionally, the photosensor 200 may be composed of a single photosensitive pixel or multiple photosensitive pixels. The photosensitive pixel is used to receive a light signal from the measurement scene and output a corresponding light-sensing signal. Each photosensitive pixel includes at least one photodetector. The photodetector is configured to sense the received light signal and convert it into a corresponding electrical signal to output as the light-sensing signal. The photodetector may be composed of a single photon avalanche diode (SPAD).

[0056] The SPAD is a solid-state photodetector device operating above its breakdown voltage, a Geiger-mode avalanche photodiode. Unlike traditional photodetectors, the SPAD has the ability to detect single photons. A single incident photon can, with a certain probability, trigger avalanche behavior in the SPAD, generating a significant avalanche current. This photon can be detected by interaction with the readout circuit.

[0057] Application Overview:

[0058] In practical applications, SPADs are generally arranged in an array, with each SPAD serving as a photosensitive pixel (also referred to as an avalanche pixel unit or pixel) to form a photoelectric sensor. In order to isolate each SPAD, an isolation structure (generally in the shape of a grid and referred to as an isolation grid / isolation grid, and subsequently referred to as an isolation structure) is provided between each avalanche pixel unit.

[0059] To further illustrate the photoelectric sensor constructed by SPAD, the present invention also provides a schematic diagram of the top view of the photoelectric sensor ( Figure 3 ).

[0060] The photoelectric sensor 200 can be presented as a semiconductor structure formed based on the diode substrate 210, that is, the diode substrate 210 can refer to the basic material forming the photoelectric sensor 200, and the specific structure of the photoelectric sensor 200 can be formed in or on the diode substrate 210 based on semiconductor processes (such as etching, deposition, etc.).

[0061] like Figure 2 As shown, the photosensor 200 may include a plurality of avalanche pixel units 220 and an isolation structure 230 for isolating the avalanche pixel units. The isolation structure 230 may be disposed around each avalanche pixel unit 220, forming a pixel space to accommodate the avalanche pixel unit 220 and isolating each pixel space. The avalanche pixel unit 220 and the isolation structure 230 may be formed within the diode substrate 210 using semiconductor processes (e.g., etching, deposition, doping, etc.).

[0062] Similar to the imaging principle of traditional pixel units, different pixel units in the aforementioned photoelectric sensor 200 can be mapped to different positions in space. When the avalanche pixel unit 220 receives a light signal (such as a single-photon light signal), an avalanche phenomenon will occur inside it to generate a corresponding electrical signal. Based on the correspondence between the presence or absence of the electrical signal and the pixel unit and space, combined with the aforementioned time-of-flight related calculation principle, three-dimensional imaging of external objects can be achieved. For details, please refer to the relevant technology and will not be elaborated here.

[0063] In addition, considering the application scenario of the avalanche pixel unit 220, in the photoelectric sensor 200, a filtering structure and a focusing structure can also be set upstream of the light beam incident light path of the avalanche pixel unit 220 to avoid ambient light interference and improve the light beam perception capability.

[0064] Specifically, within the aforementioned avalanche pixel unit 220, its most basic structure includes a P region and an N region, forming a PN junction. Furthermore, to achieve avalanche, additional doping is typically required near the junction region to enable avalanche at relatively low bias voltages. To achieve in-plane device integration, the PN junction P region and N region must be connected to the surface separately.

[0065] To further illustrate the basic functions of the avalanche pixel unit 220. The present invention also takes a planar NP type avalanche diode device as an example and provides Figure 3 Schematic diagram of the cross-sectional structure of the photoelectric conversion device at AA shown ( Figure 4 ). For the convenience of subsequent explanation, Figure 4 The stacking direction of the devices (ie, the longitudinal direction in the figure) is recorded as the vertical direction, and the extending direction of AA (the direction in the plane perpendicular to the vertical direction, ie, the lateral direction in the figure) is recorded as the horizontal direction.

[0066] To describe the specific internal structure of the avalanche pixel unit 220, this utility model only Figure 4 An avalanche pixel unit 220 and isolation structures 230 on both sides thereof are shown.

[0067] Based on the aforementioned NP type avalanche diode device, Figure 4 The diode substrate 210 of the illustrated photosensor 200 can be configured as a P-type doped substrate. Within the avalanche pixel unit 220, multiple doped regions can be included, along with electrodes (also referred to as leads or CT lines) on the surface of the diode substrate 210 that electrically connect the corresponding doped regions. Specifically, the avalanche pixel unit 220 includes an N region and a P+ region in the central region, as well as a P- region near the isolation structure 230. The + and - denote doping concentrations.

[0068] The N- and P+-regions form an avalanche region at the contact interface, separating the P- and N-regions. Electrodes extending from the N- and P-regions can sense device avalanche conditions under the influence of an external drive circuit. The P+ and P-regions are typically formed on a P-type substrate and are additionally doped for optimal device formation, though the actual structure may not require additional doping.

[0069] Figure 4 The P+ region and the N region can form a longitudinal electric field in the stacking direction of the semiconductor device (i.e., the vertical direction in the figure, hereinafter referred to as the vertical direction), and the P- region and the N region can form a transverse electric field in the array direction of the semiconductor device (i.e., the horizontal direction in the figure, hereinafter referred to as the horizontal direction).

[0070] The longitudinal electric field drifts the carriers generated by the incident photons into the avalanche region. Simultaneously, the strong longitudinal electric field in this avalanche region causes the carriers to collide and ionize with the crystal lattice. When the width of the strong electric field is sufficiently large, a self-sustaining avalanche effect can occur. The lateral electric field formed by the P- and N-regions must be suppressed to increase the lateral avalanche breakdown voltage of the PN junction. This ensures that the carrier avalanche generated by the incident light occurs within the longitudinal electric field region, i.e., the main junction region. The substrate region formed by the horizontal separation of the P- and N-regions can be referred to as the guide ring (GR).

[0071] In actual use, with the continuous development of manufacturing processes and the continuous improvement of device precision requirements, the cell size of SPADs has been continuously reduced to increase imaging resolution. However, based on the aforementioned sensing principle of SPADs, the ever-smaller size will lead to conflicts in the device structure. For example, the conflict between the size of the central avalanche region and the width of the lateral depletion region.

[0072] In related technologies, to achieve small-sized SPAD units, the current common practice is to scale down the device. However, some dimensional parameters of the SPAD's internal structure are closely related to its performance. As a result, scaling down the device can lead to multiple technical issues (such as the serious side breakdown problem, which can affect device performance). These issues / limitations can be summarized as follows:

[0073] ① Avalanche zone size limitation: When the avalanche zone becomes smaller, the probability of edge carriers entering the avalanche zone decreases, leading to a decrease in photon detection efficiency (PDE). This is especially true at small pixel sizes. The electrodes extending from the diode substrate surface often have certain size requirements (e.g., 0.3-0.4 μm). Consequently, at small pixel sizes, the avalanche zone size is further limited, affecting the PDE.

[0074] ② Limitation of edge electrode size: Similar to the aforementioned avalanche region, in actual processes, in order to enhance the light absorption and device performance of the SPAD, the aforementioned isolation structure 230 is often filled with metal material and provided with an insulating layer on both sides. In order to avoid process errors, the metal in the isolation structure and the edge electrode contact (such as Figure 4 The edge electrode on the left side of the center contacts the metal structure in the isolation structure 230 due to processing errors. Therefore, the edge doping structure also requires a certain safety distance based on design requirements. This safety distance is generally greater than the manufacturing error of the electrode (such as the metal via), for example, 0.3-0.5 μm.

[0075] ③ Guard Ring Size Limitation: Similar to the aforementioned avalanche region, to suppress the lateral electric field, the guard ring size can be increased by increasing the distance between the P and N regions, shifting the lateral PN junction toward a graded junction. This generally requires maintaining a sufficient depletion region width under a fixed bias voltage. Combined with the aforementioned size limitations, if the photosensitive pixel is designed to be 1µm, the space left for the guard ring is only approximately 0.3µm on a single side. This is a relatively risky design, potentially leading to lateral avalanches and impacting reliability. For larger pixel sizes, such as those with a 10-15µm pixel pitch, guard ring designs are often designed within or above 1µm to 3µm.

[0076] Therefore, in order to avoid the conflict in size limits of various devices when the device size is reduced, resulting in the guard ring formed by the remaining space being too compact, thereby causing side breakdown and reliability problems, it is a technical problem that technical personnel in this field urgently need to solve.

[0077] To address the technical issue of maintaining a safe distance between the metal-filled deep trench isolation layer and the edge doping structure due to process errors in electrode preparation, the present invention optimizes the isolation structure of the pixel unit by forming a shallow trench insulation layer on the metal-filled deep trench isolation layer, with the depth of the shallow trench insulation layer being greater than the etching depth during electrode preparation. As a result, even if process errors occur during electrode formation, the electrode will not connect to the metal filling within the deep trench isolation layer, eliminating the need for a minimum safe distance between the isolation structure and the edge doping structure. This allows the edge doping structure to be positioned closer to the pixel edge, thereby increasing the size of the guard ring between the center doping structure and the edge doping structure while maintaining the same size of the photoelectric conversion device, thereby improving the device performance of the photoelectric converter.

[0078] The following will be combined Figures 5 to 14 The photoelectric sensor provided by the utility model is described in detail.

[0079] Example photosensors:

[0080] In order to further illustrate the specific structure of the photoelectric sensor provided by the present invention, the present invention also provides a structural schematic diagram of a plurality of photoelectric sensors, among which: Figure 5 、 Figure 6 They are schematic diagrams of the cross-sectional structures of different photoelectric sensors. Figure 7 for Figure 6 Schematic top view of the structure of the photoelectric sensor shown.

[0081] See also Figure 5 , and the aforementioned Figure 4 similar, Figure 5 It also presents a cross-sectional structural diagram of a photosensor 200 including an avalanche pixel unit 220. Figure 5The photosensor 200 also includes a diode substrate 210, an avalanche pixel unit 220, and an isolation structure 230. The avalanche pixel unit 220 and the isolation structure 230 are also formed in the diode substrate 210 based on semiconductor technology, and the avalanche pixel unit 220 is also formed in the pixel space formed by the isolation structure 230.

[0082] With the aforementioned Figure 3 、 4 Similar to the description in , the diode substrate 210 can refer to the basic material forming the photosensor 200, which generally includes two parts: a substrate and an epitaxial layer. The substrate is the base material in the semiconductor manufacturing process, and the epitaxial layer can be a structure generated on the substrate.

[0083] The present invention does not limit the specific type of photosensor 200; instead, appropriate substrates and epitaxial layers (i.e., diode substrate 210) can be selected based on actual needs. For example, the substrate can be a silicon-based substrate, a germanium-based substrate, or a Group III-V substrate (such as an InP substrate). The substrate can be a high-purity substrate or a doped substrate. For example, the substrate can be an N-type semiconductor substrate or a P-type semiconductor substrate formed by doping. The epitaxial layer is similar to the substrate. In the subsequent description of this application, the epitaxial layer and substrate are considered to be integrated and not described separately.

[0084] To facilitate description of the structure formed within the diode substrate 210, two vertically opposing surfaces of the diode substrate 210 may be referred to as a first surface 211 and a second surface 212, respectively. Considering the connection between the diode substrate 210 and the metal wiring layer (also known as a metal wiring layer, back-end process layer, etc.) in the photosensor 200, the second surface 212 of the diode substrate 210 may be the side bonded to the metal wiring layer. In other words, the electrodes in the avalanche pixel unit 220 are primarily formed on the second surface 212 and are thus electrically connected to the metal wiring layer via corresponding electrodes.

[0085] The present invention does not limit the connection relationship between the photoelectric sensor 200 and other hierarchical structures. For example, when the photoelectric sensor 200 adopts a back-illuminated structure, the first surface 211 generally faces the incident light, and a filter layer and a light collection layer are generally provided in the upstream optical path of the incident light.

[0086] The isolation structure 230 is generally the main part of the isolation structure within the diode substrate 210, that is, the isolation structure 230 can block the lateral crosstalk between different avalanche pixel units 220, but the avalanche pixel unit 220 only reflects the single-photon beam situation in its corresponding space. Correspondingly, the isolation structure 230 is set based on the above-mentioned setting requirements, and generally needs to form pixel areas that are isolated from each other and used to accommodate the avalanche pixel units 220. Considering that the avalanche pixel unit 220 generally forms an electrode on the second surface 212, its main structure is often set close to the second surface 212, and the isolation structure 230 often needs to be set from the inside of the diode substrate 210 close to the first surface 211 (or directly from the first surface 211, that is, Figure 4 、 5 The isolation structure 230 directly penetrates the diode substrate 210 and extends to the second surface 212 to isolate each avalanche pixel unit 220 .

[0087] The conventional isolation structure 230 may be presented as Figure 4 The structure shown is typically constructed using deep trench isolation (DTI / W-DTI) technology. Metal is filled into the deep isolation trenches, and isolation layers are formed on both sides of the metal to enhance signal isolation and light reflection isolation. The present invention further improves isolation structure 230, transforming it into a complex, hierarchical structure. This primary structure is referred to herein as deep trench isolation layer 231.

[0088] Different from Figure 4 The middle isolation structure 230 (i.e., the deep trench isolation layer) extends to the second surface 212. The deep trench isolation layer 231 of the present invention does not extend to the second surface 212, but is vertically spaced a certain distance from the second surface 212. Specifically, the vertical distance between the side of the deep trench isolation layer 231 closest to the second surface 212 and the second surface 212 is greater than the etching depth (referred to as the electrode formation depth) used to form the electrode on the second surface 212. Therefore, even if process errors occur during electrode formation, the resulting electrode will not connect to the metal filling in the deep trench isolation layer 231.

[0089] Specifically, the metal filling within the aforementioned deep trench isolation layer 231 can be referred to as a metal isolation structure 2311, and the insulating layers on both sides thereof can be referred to as insulating sidewalls 2312. The metal isolation structure 2311 is generally constructed from metal or other highly reflective materials, primarily a docking metal isolation structure. Aluminum, copper, and the like can also be used as materials for forming the metal isolation structure 2311. The insulating sidewalls 2312 are primarily used to electrically isolate the metal isolation structure 2311 from the substrate and are generally constructed from insulating materials such as silicon oxide.

[0090] The metal isolation structure 2311 and insulating sidewalls 2312 provide electrical isolation between adjacent pixels, effectively suppressing crosstalk between optical and electrical signals. Specifically, the high conductivity of the metal material provides electromagnetic shielding, while its high reflectivity reflects unabsorbed photons back into the avalanche region, improving photon detection efficiency.

[0091] Considering that the deep trench isolation layer 231 does not extend to the second surface 212 , the space between the deep trench isolation layer 231 and the second surface 212 can be filled with other isolation structures. ie, the isolation structure 230 can further include a shallow trench insulation layer 232 .

[0092] The shallow trench insulation layer 232 may refer to a supplementary isolation structure that supplements the unisolated areas of the deep trench isolation layer 231 within the diode substrate 210. Specifically, it extends from the side of the deep trench isolation layer 231 near the second surface 212 toward the second surface 212. In other words, the shallow trench insulation layer 232 may fill the area between the deep trench isolation layer 231 and the second surface 212 (this may also be described as the shallow trench insulation layer 232 being formed vertically on the deep trench isolation layer 231 and near the second surface 212). Whether it specifically extends to the second surface 212 may depend on the structural relationship between the shallow trench insulation layer 232 and the subsequent edge doping structure 222.

[0093] Specifically, in Figure 5 In the illustrated structure, the STI layer 232 extends to the second surface 212 . Figure 6 In the structure shown, the shallow trench isolation layer 232 partially extends to the second surface 212 or extends to the bottom surface of the edge doping structure 222 (in this case, the edge doping structure 222 is disposed on the isolation structure 230 ).

[0094] At the fabrication level, the shallow trench insulation layer 232 is typically fabricated using a shallow trench isolation (STI) process. Specifically, when forming the shallow trench insulation layer 232, trenches filled with an insulating material are formed on the deep trench isolation layer 231 using STI technology to isolate the deep trench isolation layer 231 from the edge doping structure 222. The insulating material used for the shallow trench insulation layer 232 is typically a light-transmitting insulating material such as silicon oxide.

[0095] As previously mentioned, the shallow trench insulation layer 232 can directly prevent the edge doping structure 222 from connecting to the metal isolation structure 2311 due to process errors during electrode formation. This eliminates the horizontal safety distance between the metal isolation structure 2311 and the edge doping structure 222, allowing the edge doping structure 222 to be positioned as close to the isolation structure 230 as possible. To prevent the shallow trench insulation layer 232 from occupying this safety distance, the shallow trench insulation layer 232 does not occupy additional horizontal space. In other words, the horizontal dimension of the shallow trench insulation layer 232 is no greater than the horizontal dimension of the deep trench isolation layer 231.

[0096] Furthermore, considering the aforementioned vertical distance limit between the deep trench isolation layer 231 and the second surface 212, and considering that the shallow trench insulation layer 232 fills the gap between the deep trench isolation layer 231 and the second surface 212, the shallow trench insulation layer 232 should also meet this distance limit. That is, the vertical distance between the side of the shallow trench insulation layer 232 away from the second surface 212 and the second surface 212 is greater than the electrode formation depth.

[0097] With the aforementioned Figure 4 The structure shown is similar to Figure 5 The medium avalanche pixel unit 220 may include a central doping structure 221, an edge doping structure 222, a central electrode 223, and an edge electrode 224. The central doping structure 221 and the edge doping structure 222 are formed on a side of the diode substrate 210 close to the second surface 212, while the central electrode 223 and the edge electrode 224 are formed on the second surface 212.

[0098] The central doped structure 221 is electrically connected to the central electrode 223 and driven by the central electrode 223. The edge doped structure 222 is electrically connected to the edge electrode 224 and driven by the edge electrode 224. The multilayer doped structure within the central doped structure 221, driven by the central electrode 223, forms a longitudinal electric field, forming an avalanche region 225 within the structure (if the avalanche region is not formed by multilayer doping but by the doped substrate, it can also be considered as the avalanche region 225 within the structure). The avalanche region 225 can generate an avalanche signal in response to a single-photon beam, which is then output at the central electrode 223 and the edge electrode 224.

[0099] Specifically, the portion inside the central doping structure 221 with a different doping type from the edge doping structure 222 and the portion inside the central doping structure 221 or in the diode base material 210 (such as a substrate) with the same doping type as the edge doping structure 222 form a PN junction (which can also be extended to a PIN junction) in the vertical direction, thereby forming an avalanche region 225.

[0100] In accordance with the aforementioned device performance requirements, the central doping structure 221 and the edge doping structure 222 are separated horizontally on the second surface 212 to form a guard ring 226. An electric field channel exists in the diode substrate 210 from the central doping structure 221 to the edge doping structure 222, thereby forming a lateral suppression electric field between the central electrode 223 and the edge electrode 224.

[0101] In addition, the central doping structure 221 and the edge doping structure 222 are generally formed based on ion implantation / deposition processes. The specific type of configuration is related to the type of the photoelectric sensor 200 itself and the selection of the aforementioned diode substrate 210. The specific configuration can be adaptively adjusted and will not be elaborated here.

[0102] like Figure 5 As shown, the central doping structure 221 and the edge doping structure 222 are generally exposed on the second surface 212 to facilitate connection to the electrode and its metal wiring layer. Furthermore, the central doping structure 221 and the edge doping structure 222 are formed within the diode substrate 210. The edge doping structure 222 is often formed directly on the second surface 212, while the central doping structure 221 can be formed directly on the second surface 212 or connected to the second surface 212 via a connecting structure. The specific structures can be adjusted adaptively.

[0103] Based on the aforementioned avoidance of the deep trench isolation layer 231 at the second surface 212 and the supplementation of the shallow trench insulation layer 232 to the deep trench isolation layer 231 near the second surface 212, the aforementioned edge doping structure 222 can be formed near the shallow trench insulation layer 232. In this case, the edge doping structure 222 is electrically isolated from the deep trench isolation layer 231 by the shallow trench insulation layer 232, without the need to maintain the aforementioned safety distance (for example, the bottom surface (the side away from the second surface) and / or sidewall of the edge doping structure 222 can be in contact with the shallow trench insulation layer 232).

[0104] For example, the aforementioned edge doping structure 222 may be presented as a deep well formed close to the shallow trench insulating layer 232, with the sidewall of the structure being aligned with the shallow trench insulating layer 232. The vertical dimension of the deep well-shaped edge doping structure 222 is often greater than the depth of the shallow trench insulating layer 232 (e.g., Figure 5 edge doping structure 222 on the left side of the figure).

[0105] For another example, to prevent the edge doping structure 222 from being electrically connected to the metal isolation structure 2311 due to process errors of the insulating sidewall 2312, the vertical dimension of the edge doping structure 222 may be smaller than the depth of the shallow trench insulating layer 232 (e.g., Figure 5 edge doping structure 222 on the right side of the middle).

[0106] In addition, the specific structures of the central doping structure 221 and the edge doping structure 222 can be optimized according to conventional settings in the art. For example, the central doping structure 221 and the edge doping structure 222 can have a higher doping concentration at the connection with the electrode in the second surface 212 to improve the electrical connection stability.

[0107] In summary, to address the technical issue of maintaining a safe distance between the metal-filled deep trench isolation layer and the edge doping structure due to process errors in electrode preparation, the aforementioned photosensor optimizes the isolation structure of the pixel unit, forming a shallow trench insulation layer on the metal-filled deep trench isolation layer, with the depth of the shallow trench insulation layer being greater than the etching depth during electrode preparation. As a result, even if process errors occur during electrode formation, the electrode will not connect to the metal filling in the deep trench isolation layer, eliminating the need for a minimum safe distance between the isolation structure and the edge doping structure. This allows the edge doping structure to be positioned closer to the pixel edge, thereby increasing the size of the guard ring between the center doping structure and the edge doping structure while maintaining the same size of the photosensor, thereby improving the device performance of the photoelectric converter.

[0108] In some embodiments, the size of the guard ring is increased to further reduce the distance between the edge doping structure 222 and the diode edge. The sidewalls and at least a portion of the bottom edge of the edge doping structure 222 may be completely located in the space between the deep trench isolation layer 231 and the second surface 212 .

[0109] Specifically, see Figure 6 In the photosensor 200 shown, the vertical projection of the edge doping structure 222 at least partially overlaps with the vertical projection of the deep trench isolation layer 231 , so that the edge doping structure 222 occupies the diode edge structure, further reducing the distance between the edge doping structure 222 and the diode edge.

[0110] Furthermore, the overlap of the aforementioned projections may include two situations:

[0111] First, a sidewall of the edge doping structure 222 and a portion of its bottom edge are embedded in the shallow trench insulating layer 232 (see Figure 6 At this time, the other sidewall of the edge doping structure 222 leaks out relative to the shallow trench insulating layer 232, and a conductive channel exists between the edge doping structure 222 and the central doping structure 221, thereby forming a guard ring 226.

[0112] Secondly, the edge doping structure 222 directly crosses the isolation structure 230 and extends into two adjacent avalanche pixel units. Figure 6 The edge doping structure 222 on the right side, in addition to the current avalanche pixel unit 220, also extends to the pixel unit on the right side of the avalanche pixel unit 220. At this time, the side of the edge doping structure 222 away from the second surface 212 is isolated from the side of the deep trench isolation layer 231 close to the second surface 212 by the shallow trench insulation layer 232. The edge doping structure 222 can be electrically connected to the edge electrodes of each avalanche pixel unit in the two adjacent avalanche pixel units (i.e., Figure 6The edge doping structure 222 on the right is shown as electrically connected to both the edge electrode 224 of the pixel unit and the edge electrode (not numbered) of the pixel unit to the right. The specific horizontal dimensions of the edge doping structure 222 are not limited; it only needs to be electrically connected to the edge electrode 224 (in some embodiments, two avalanche pixel units can share a single edge electrode 224) and able to generate a lateral electric field in both adjacent avalanche pixel units (i.e., the sidewalls of the edge doping structure 222 are exposed relative to the shallow trench insulating layer 232).

[0113] Furthermore, the present invention also shows that based on the above Figure 6 A schematic top view of the photoelectric sensor 200 with the edge doping structure 222 on the right ( Figure 7 ).

[0114] like Figure 7 As shown, the sides of each avalanche pixel unit 220 share an edge doping structure 222, and the isolation structure 230 is exposed at the corners of the avalanche pixel unit 220. As a result, the edge doping structures 222 are not connected to each other, which facilitates control. In some alternative embodiments, the edge doping structures 222 can also be interconnected to completely cover the isolation structure 230.

[0115] In some embodiments, in order to ensure that the internal potential of the edge doping structure 222 is uniform, the arrangement of the edge electrode 224 can also be optimized so that it is not arranged on different avalanche pixel units 220 based on the avalanche pixel units 220, but is arranged on the edge doping structure 222 along the extension direction of the isolation structure 230 (e.g., Figure 7 As shown in the avalanche pixel unit 220 in the center). This can further ensure that the potential of the edge doping structure 222 is the same, while further reducing the "horizontal direction" size requirement of the edge doping structure 222, thereby further increasing the size of the guard ring 226.

[0116] In summary Figures 5 to 7 The photoelectric sensor 200 shown creatively transforms the planar distance relationship of "edge electrode-safety distance-deep trench isolation layer" on the second plane into a combination of the planar distance relationship of "edge electrode-shallow trench insulation layer" in the horizontal direction and the depth distance relationship of "shallow trench insulation layer-deep trench isolation layer" in the vertical direction (which can also be transformed into the depth distance relationship of "edge electrode-shallow trench insulation layer-deep trench isolation layer") by avoiding the deep trench isolation layer and filling the shallow trench insulation layer. This removes the size limitation of the planar distance relationship of "edge electrode-safety distance-deep trench isolation layer" and enables the shallow trench insulation layer to be as close to the edge of the diode as possible, thereby leaving more guard ring size to improve the device performance of the photoelectric sensor.

[0117] In some embodiments, in order to reduce the space waste caused by the isolation structure 230, the pixel unit provided by the present invention can be further composed of multiple pixel sub-units, each pixel sub-unit has independent photosensitivity and the aforementioned isolation structure 230 does not exist between the pixel sub-units.

[0118] To further illustrate the photoelectric sensor 200 in the aforementioned case, the present invention also provides a cross-sectional schematic diagram thereof ( Figure 8 ).

[0119] like Figure 8 As shown, in order to form a plurality of pixel subunits 227, the avalanche pixel unit 220 includes a plurality of central doping structures 221, wherein the plurality of central doping structures 221 form a plurality of pixel subunits 227, and the central doping structures 221 correspond to the pixel subunits 227 one by one and are arranged in the central area of the corresponding pixel subunit 227. Specifically, Figure 8 The avalanche pixel unit 220 shown includes two pixel sub-units 227 and a central doping structure 221 in the central region thereof.

[0120] In the avalanche pixel unit 220, the edge doping structure 222 is disposed in a pixel subunit adjacent to the deep trench isolation layer among the plurality of pixel subunits 227 and is located close to the side of the deep trench isolation layer 231. Figure 8 If both pixel subunits are adjacent to the isolation structure 230, they are both provided with the edge doping structure 222. If the avalanche pixel unit 220 includes three or more pixel subunits in cross section, the pixel subunits away from the isolation structure 230 are not provided with the edge doping structure 222.

[0121] Considering that the aforementioned edge doping structure 222 is only provided in a portion of the area and no isolation structure exists between the pixel sub-units, to prevent depletion layer connection between the pixel sub-units, a lightly doped structure 228 is provided in an area away from the deep trench isolation layer 231 in two adjacent pixel sub-units among the multiple pixel sub-units. The lightly doped structure 228 has the same doping type as the edge doping structure 222, thereby isolating the depletion layers between different pixel sub-units. As just one exemplary embodiment, the lightly doped structure 228 can be composed of boron.

[0122] Furthermore, considering that the pixel sub-units adjacent to the deep trench isolation layer in the multiple pixel sub-units are all provided with an edge doping structure 222, and their internal potential can be directly adjusted by the edge doping structure 222, the aforementioned lightly doped structure 228 for isolating different pixel sub-units can be configured as a passive structure, that is, the lightly doped structure 228 is not electrically connected to the external electrode.

[0123] Thus, the lightly doped structure 228 (eg, Figure 8 The dimensions of the lightly doped structure 228 as shown may not be affected by the nature of the external electrodes and thus may be configured as a narrower doped structure.

[0124] For pixel subunits not adjacent to the deep trench isolation layer, if their lightly doped structures can be at a suitable potential, they do not need to be connected to external electrodes; otherwise, they can be connected to external electrodes.

[0125] To further illustrate the composition of the above structure, the present invention also provides Figure 8 The top view of the photoelectric sensor shown in the figure ( Figure 9 ).

[0126] like Figure 9 As shown, in a top view, an array of four pixel subunits 227 can be arranged to form an avalanche pixel unit 220. Each pixel subunit 227 has a central doping structure 221 inside, an edge doping structure 222 is arranged on a side of each pixel subunit 227 close to the isolation structure 230, and a passive lightly doped structure 228 is arranged between each pixel subunit 227.

[0127] Therefore, based on the above Figure 8 、 9 The photosensor shown in the figure reduces the space occupied by isolation structures by packaging multiple pixel units into a single pixel unit. Furthermore, the pixel subunits are isolated and separated by passive lightly doped structures, eliminating the need to consider electrode connection requirements for the individual lightly doped structures, further reducing their size requirements.

[0128] The present invention further finds that the distribution of the edge doping structure in the horizontal plane can be further optimized, thereby increasing the size of the guard ring.

[0129] To further illustrate the process, the present invention takes the horizontal plane distribution of the edge doping structure of a conventional photoelectric sensor as an example. That is, the present invention also provides a ( Figure 5 Schematic diagram of the top view of the photoelectric sensor (shown) Figure 10 ). To facilitate the description of the arrangement of a single diode, the subsequent top view only shows one avalanche pixel unit.

[0130] like Figure 10 As shown, the edge doping structure 222 is generally arranged with a constant thickness along the interior of the isolation structure 230, without considering the safe distance from the isolation structure 230. For the isolation structure 230 that generally isolates a rectangular or square pixel space (also referred to as a square / rectangular pixel edge), this may result in different shortest distances from each point on the pixel edge of the avalanche pixel unit (i.e., inside the isolation structure) to the central doping structure.

[0131] by Figure 10 Taking the positive direction pixel space (the inner wall of the isolation structure 230 forms a square) and the circular central doping structure 221 as an example, the distance from the midpoint of the straight side of the rectangle (formed by the inner wall of the isolation structure 230) to the central doping structure 221 can be the minimum value D among the shortest distances from the pixel edge of the avalanche pixel unit to the central doping structure. emin , and the distance from the right angle of the rectangle to the central doping structure 221 can be the maximum value D in the shortest distance from the edge of the pixel of the avalanche pixel unit to the central doping structure emax .

[0132] If the edge doping structure 222 is provided along the interior of the isolation structure 230 with equal thickness based on the conventional design concept, the aforementioned D emin The guard ring size at the D is smaller to make it easier to be penetrated. emax The edge doping structure 222 / guard ring cannot share the breakdown risk.

[0133] Therefore, considering the irrationality of the above-mentioned horizontal plane distribution, the present invention optimizes the distribution and provides Figures 11 to 14 Schematic diagrams of various top views of structures shown.

[0134] Based on the above, considering the above D emin The guard ring size at the D emax The protection ring at D can not share the breakdown risk. When the edge doping structure is doped, the utility model can be based on this situation to emin The edge doping structure at D emax Transfer to increase D emin The size of the protective ring.

[0135] Therefore, the width D of the guard ring gr The following relationship is satisfied:

[0136] D emin -W avg <D gr <D emax -W avg , where W avg is the average size of the edge-doped structure in the horizontal direction.

[0137] To further describe the difference between this distribution and the traditional distribution, the present invention Figure 11 A photoelectric sensor optimized based on the above logic is provided.

[0138] like Figure 11 As shown, the edge doping structure 222 is from D emin (and its vicinity) to D emaxTransfer and accumulate at the right angles of the rectangle. Figure 11 Also shown in dotted lines Figure 10 The distribution of edge doping structures in the. Figure 11 The actual distribution of the edge doping structure 222 and the dotted line (which also reflects the average size of the edge doping structure in the horizontal direction) can be clearly seen. emin (and its vicinity) to D emax Transfer and stack at the right angle of the rectangle so that the width D of the protection ring gr Meet the above requirements.

[0139] Furthermore, considering the breakdown probability of the guard ring at each point, as a preferred embodiment, the width D of the guard ring is gr The doping structure 222 is constant and forms a ring-shaped edge surrounding the central doping structure.

[0140] based on Figure 11 In the case shown, the present invention also provides a schematic diagram of a protective ring forming a ring structure ( Figure 12 ).like Figure 12 As shown, in Figure 12 The middle guard ring may be directly presented as a circular ring having the same center as the central doping structure, and the edge doping structure 222 is filled between the circular ring and the edge of the pixel.

[0141] In addition, as a preferred embodiment, Figure 12 In the case of a CMOS process, the guard ring can be extended directly to the edge of the pixel within the tolerance range to make D gr ≈D emin (or D gr =D emin ) Among them, generally some edge doping structures should be retained at the edges to connect the edge doping structures at each right angle (considering the situation of setting electrodes directly at the right angles later, it is also possible not to retain them).

[0142] To illustrate the guard ring shape under other forms of the central doping structure, the present invention Figure 13 Also shown is the guard ring morphology when the central doping structure is in the form of a square.

[0143] like Figure 13 As shown, based on the central doping structure of a square, its guard ring can be presented as a rounded rectangle, where the straight sides of the rounded rectangle are equidistant from the straight sides of the square, and the corners of the rounded rectangle are represented by a quarter circle with the right corner of the square as the center and the distance between the two as the radius. Therefore, the distance from any point in the rounded rectangle to the positive direction is equal.

[0144] Based on the shortest distance D from the edge of the pixel to the central doping structure of the aforementioned avalanche pixel unite When the value is not constant, the edge doping structure often accumulates on D emax Therefore, the area of the doped structure here is larger and it is easier to meet the size requirements when the electrode is formed. e When the value is not constant, the pixel edge is at D emin parallel to the annular edge, and at D emax The edge is not parallel to the annular edge and forms an edge bend, and the edge electrode is arranged between the edge bend and the annular edge.

[0145] Specifically, the aforementioned pixel edge is at D emin Parallel to the annular edge may include parallel to the tangential direction (such as Figure 11 / 12) and the actual parallelism (e.g. Figure 13 In the case where the straight sides of the rectangular portion are parallel to the straight sides of the rectangular center doped structure, the corresponding aforementioned edge bends are often formed between the parallel structures. Figures 11 to 13 In the structures shown, edge bending structures are formed at right angles, where edge electrodes can be arranged.

[0146] Combined with the above Figures 11 to 13 It can be seen that the pixel space is configured as a rectangle, and the edge is bent into a rectangular right-angle area. The minimum value D of the shortest distance between the pixel edge of the avalanche pixel unit and the central doping structure is emin The maximum value D of the shortest distance between the edge of the pixel of the avalanche pixel unit and the central doping structure is emax It is the shortest distance between the right corner of the rectangle and the central doped structure.

[0147] Except for the above Figures 11 to 13 In addition to the illustrated example, the pixel space may also be configured in other forms. Generally, to achieve the densest arrangement of the pixel space, the pixel space may be in the form of a regular hexagon.

[0148] In addition, in some embodiments, the shortest distance D between the edge of the pixel of the avalanche pixel unit and the central doping structure is e It can also be a constant value. In this case, the pixel edge and the central doping structure of the avalanche pixel unit generally present concentric circles (or concentric rounded polygons). In this case, the above-mentioned equal thickness distribution can be directly adopted to make the width D of the guard ring gr =D e -W avg For details, please refer to Figure 14 The situation shown.

[0149] However, in practice, considering that when the pixel edges are circular, the densest arrangement is often not achieved, which may result in a waste of space. It can also be converted into a square or a regular hexagon based on the above arrangement requirements.

[0150] In summary, the adjustment of the distribution of the edge doping structure can achieve the optimized distribution (or optimal distribution) of the edge doping structure by ensuring that the closest distance from any point on the side of the central doping structure close to the edge doping structure to the central doping structure is significantly increased.

[0151] Based on the above Figures 5 to 14 The present invention optimizes the placement and area of the edge doping structure 222 to increase the size of the guard ring. In practical photoelectric sensors, the size of the guard ring is also related to the central doping structure 221, and optimization of the central doping structure 221 can also be used to further increase the size of the guard ring.

[0152] In practice, the central doping structure 221 can be split into an avalanche doping structure 2211 and a connecting structure 2212 based on the size of the central electrode 223. The avalanche doping structure 2211 can be used to form the avalanche region 225, while the connecting structure 2212 can be used to connect the avalanche doping structure 2211 to the central electrode 223. As a result, the avalanche doping structure 2211 can be sunken into the diode substrate 210 and away from the second surface 212 based on the connecting structure 2212. In this case, the "lateral suppression electric field" between the avalanche doping structure 2211 and the edge doping structure 222 is tilted, increasing their length.

[0153] To further illustrate the above situation, the present invention also provides a cross-sectional schematic diagram based on the above connection structure ( Figure 15 ).

[0154] like Figure 15 As shown, the central doping structure 221 may further include an avalanche doping structure 2211 and a connecting structure 2212. The avalanche doping structure 2211 is sunken into the diode substrate 210 and then electrically connected to the avalanche doping structure 2211 via the connecting structure 2212. The avalanche doping structure 2211 may be a doping structure for forming an avalanche region, i.e., the avalanche doping structure 2211 is used to form an avalanche region 225 in the vertical direction and form a lateral suppression electric field (i.e., a guard ring 226) with the edge doping structure 222.

[0155] Based on the above-mentioned setting, the avalanche doping structure 2211 is far away from the surface where the edge doping structure 222 is located, so that the avalanche doping structure 2211 and the edge doping structure 222 are separated both in the horizontal direction and in the vertical direction, so that the electric field path length of the lateral suppression electric field is greater than the projection distance between the avalanche doping structure 2211 and the edge doping structure 222 in the vertical direction.

[0156] Specifically, in combination with the above-mentioned separation situation, the horizontal distance between the avalanche doping structure 2211 and the edge doping structure 222 is d1 (i.e., the projection distance between the central doping structure and the edge doping structure in the vertical direction is d1), and the vertical distance is d2 (i.e., the projection distance between the central doping structure and the edge doping structure in the horizontal direction is d2).

[0157] Based on the aforementioned principle of horizontal suppression electric field formation, the "horizontal suppression electric field" is formed at the edges of the avalanche doping structure 2211 and the edge doping structure 222, where they are close to each other. Furthermore, considering that the avalanche doping structure 2211 and the edge doping structure 222 are separated horizontally and vertically, the path from the avalanche doping structure 2211 to the edge doping structure 222 traverses both the horizontal and vertical directions, resulting in a tilted "horizontal suppression electric field" in curved space. Consequently, the corresponding guard ring formed based on the horizontal suppression electric field is also bent by this arrangement.

[0158] The distance of the aforementioned inclined electric field (electric field distance) can be characterized as the distance between the edge of the central doping structure and the edge of the edge doping structure. Based on the aforementioned separation, the electric field path length d e Approximately . So the size of the guard ring is also approximately .

[0159] Based on the aforementioned guard ring size formula, the guard ring size is no longer only affected by the horizontal distance d1. When the horizontal distance between the central doping structure and the edge doping structure is limited, the guard ring size can be increased by the vertical distance d2.

[0160] In some embodiments, the connection structure 2212 can be electrically conductive to achieve electrical connection between the avalanche doping structure 2211 and the center electrode 223. For example, the connection structure 2212 can also be configured as a lead structure (such as a metal guide) or a doping structure. The electrical connection capability of the lead structure is not discussed here. Regarding the connection structure 2212 formed by doping, the connection structure 2212 can be specifically configured as a doping structure with electrical conductivity, and the doping type of the connection structure 2212 is opposite to that of the edge doping structure 222. Specifically, one end of the connection structure 2212 is formed on the second surface 212, and the other end is formed on the side of the avalanche doping structure 2211 close to the second surface 212.

[0161] Considering that the edge doping structure 222 is formed on the second surface 212, a lateral suppression electric field may be formed between the connection structure 2212 and the edge doping structure 222. To avoid this, the connection structure 2212 can be optimized in terms of doping concentration and device size.

[0162] In terms of doping concentration, the doping concentration of the connecting structure near the horizontal edge of the first central structure is lower than the doping concentration of the first central structure (i.e., the doping concentration of the edge of the connecting structure near the edge doping structure is low / undoped), so that a lateral inhibition electric field is not formed between its side and the edge doping structure 222.

[0163] In terms of size, the horizontal dimensions of the connecting structure can be directly reduced, making it smaller than the first central structure. This further increases the horizontal distance between the connecting structure and the edge doping structure, so that their horizontal distance approximates the electric field path length between the first central structure and the edge doping structure.

[0164] Furthermore, to prevent the edge doping structure from extending from the second surface beyond the connecting structure and thereby directly forming a lateral suppression electric field with the first central structure in the horizontal direction, the "depth" of the edge doping structure should be smaller than the "depth" of the connecting structure. That is, the edge doping structure should extend from the second surface into the diode substrate and the vertical extension depth of the edge doping structure should be smaller than the vertical extension depth of the connecting structure.

[0165] In some embodiments, in order to further isolate the isolation capability between the connection structure 2212 and the edge doping structure 222 to avoid breakdown between the connection structure 2212 and the edge doping structure 222, the aforementioned avalanche pixel unit 220 can also set a plurality of isolation trenches 229 filled with insulating material between the connection structure 2212 and the edge doping structure 222 to form an isolation trench array.

[0166] In some embodiments, the isolation trenches 229 can be filled with reflective and / or translucent materials (e.g., silicon oxide at the edges and reflective metal inside) to direct light reaching the isolation trenches 229 into the central doped structure 221. In this case, the isolation trenches 229 can also function as optical scattering structures. Specifically, the isolation trench array is multiplexed into an optical scattering structure, allowing light beams reaching the optical scattering structures to be reflected back to the avalanche pixel unit 220 by the optical scattering structures, further enhancing the avalanche pixel unit 220's ability to sense photons.

[0167] In addition, if the aforementioned optical scattering structure is disposed between the connecting structure 2212 and the edge doping structure 222 , the size limitation of the aforementioned connecting structure 2212 shrinking inward can be alleviated.

[0168] In some embodiments, considering that the aforementioned second surface 212 is often connected to a metal connection layer and the actual light-entering side of the diode is generally the first surface 211, the photosensor 200 may further include a plurality of light-absorbing holes 240 disposed on the first surface 211 to form a light-absorbing hole array. This light-absorbing hole array can enhance the light-absorbing capability of the first surface 211 based on the light-absorbing properties of the holes.

[0169] Based on the photoelectric sensor provided in the aforementioned content, one embodiment of this specification provides a photoelectric detection device, which includes any of the above-mentioned photoelectric sensors. The photoelectric detection device obtains relevant information by sensing the electrical signal generated by the corresponding light signal received by the photoelectric sensor. For example, the photoelectric detection device may include a transmitting component, a receiving component, and a processing module. The transmitting component transmits a sensing light signal into the measurement scene. The receiving component includes a photoelectric sensor to sense the sensing light signal reflected by an external object and output a corresponding electrical signal. The processing module obtains distance information of the external object by processing and analyzing the output electrical signal. The photoelectric detection device may include multiple photoelectric sensors arranged in an array. The photoelectric detection device may be a sensing chip or a sensing circuit. For example, the photoelectric sensing device may be a proximity sensor, a time of flight (TOF) sensor, a lidar, etc.

[0170] On this basis, an embodiment of this specification provides an electronic device, which includes a photoelectric detection device, and the electronic device is used to perform corresponding functions according to relevant information obtained by sensing electrical signals by the photoelectric detection device.

[0171] The corresponding functions include but are not limited to unlocking after identifying the user's identity, payment, launching preset applications, obstacle avoidance, and using deep learning technology to judge the user's emotions and health status after recognizing the user's facial expressions.

[0172] The electronic device can be any suitable type of electronic product, including consumer electronics, home electronics, smart mobile tools, and financial terminal products. Consumer electronics products can include mobile phones, tablets, laptops, desktop monitors, all-in-one computers, and the like. Home electronics can include smart door locks, televisions, refrigerators, wearable devices, and the like. Smart mobile tools can include cars, robots, and unmanned delivery vehicles. Financial terminal products can include ATMs and self-service terminals.

[0173] The above are merely specific embodiments of this specification, but the scope of protection of this utility model is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this specification should be included within the scope of protection of this specification. Therefore, the scope of protection of this utility model should be based on the scope of protection of the claims.

Claims

1. A photoelectric sensor, characterized in that: include: A diode substrate, wherein the diode substrate has a first surface and a second surface opposite to each other in a vertical direction; A plurality of avalanche pixel units disposed in the diode substrate and an isolation structure for isolating the avalanche pixel units; The isolation structure includes a deep trench isolation layer and a shallow trench insulation layer, wherein the shallow trench insulation layer is formed on the deep trench isolation layer in a vertical direction and close to the second surface, the distance between the shallow trench insulation layer and the second surface is greater than the electrode formation depth, and the horizontal dimension of the shallow trench insulation layer is no greater than the horizontal dimension of the deep trench isolation layer; The avalanche pixel unit includes a central electrode, an edge electrode, a central doping structure, and an edge doping structure; wherein the central electrode and the edge electrode are arranged on the second surface, the central doping structure and the edge doping structure extend from the second surface into the interior of the diode substrate in a vertical direction and are separated in a horizontal direction within the diode substrate, the central doping structure is electrically connected to the central electrode, and the edge electrode is arranged on the edge doping structure along the extension direction of the isolation structure; The portion of the central doping structure having a different doping type from that of the edge doping structure forms an avalanche zone along the vertical direction, and a guard ring is formed between the central doping structure and the edge doping structure along the horizontal direction; the edge doping structure is arranged close to the shallow trench insulation layer and is electrically isolated from the deep trench isolation layer by the shallow trench insulation layer.

2. The photoelectric sensor according to claim 1, wherein: The vertical dimension of the edge doping structure is smaller than the vertical dimension of the shallow trench isolation layer, and the projection of the edge doping structure along the vertical direction at least partially overlaps with the projection of the deep trench isolation layer along the vertical direction.

3. The photoelectric sensor according to claim 2, wherein: The edge doping structure crosses the isolation structure and extends into two adjacent avalanche pixel units, and is electrically connected to the edge electrodes of each of the two adjacent avalanche pixel units; A side of the edge doping structure away from the second surface and a side of the deep trench isolation layer close to the second surface are isolated by the shallow trench insulation layer.

4. The photoelectric sensor according to claim 3, wherein: The avalanche pixel unit includes a plurality of central doping structures, wherein the plurality of central doping structures form a plurality of pixel sub-units, and the central doping structures correspond to the pixel sub-units one by one and are arranged in the central area of the corresponding pixel sub-units; The edge doping structure is disposed in a pixel subunit adjacent to the deep trench isolation layer among the plurality of pixel subunits and is located close to one side of the deep trench isolation layer; A lightly doped structure is provided in a region away from the deep trench isolation layer in two adjacent pixel sub-units among the plurality of pixel sub-units, wherein the lightly doped structure has the same doping type as the edge doping structure.

5. The photoelectric sensor according to claim 4, characterized in that The lightly doped structure in the pixel sub-unit adjacent to the deep trench isolation layer among the plurality of pixel sub-units is not electrically connected to the external electrode.

6. The photoelectric sensor according to claim 1, wherein: When the pixel edge of the avalanche pixel unit reaches the minimum value D of the shortest distance of the central doping structure emin With the maximum value D emax The width D of the guard ring is not equal to gr The following relationship is satisfied: D emin -W avg <D gr <D emax -W avg , where W avg is the average size of the edge doping structure in the horizontal direction.

7. The photoelectric sensor according to claim 6, characterized in that The width D of the guard ring gr The doped structure is constant to form an annular edge surrounding the central doped structure.

8. The photoelectric sensor according to claim 7, characterized in that The pixel edge is at D emin parallel to the annular edge, and at D emax The edge electrode is not parallel to the annular edge and forms an edge bend, and the edge electrode is arranged between the edge bend and the annular edge.

9. The photoelectric sensor according to claim 8, characterized in that The pixel space is configured as a rectangle, and the edge is bent into a rectangular right-angled area; The minimum value D of the shortest distance between the pixel edge of the avalanche pixel unit and the central doping structure emin is the shortest distance between the midpoint of the right-angle side and the central doping structure; The maximum value D in the shortest distance from the pixel edge of the avalanche pixel unit to the central doping structure emax It is the shortest distance between the right angle of the rectangle and the central doping structure.

10. The photoelectric sensor according to claim 1, wherein When the pixel edge of the avalanche pixel unit reaches the shortest distance D of the central doping structure e is a constant value, the width D of the guard ring gr =D e -W avg , W avg is the average size of the edge doping structure in the horizontal direction.

11. A photoelectric detection device, characterized in that: The photoelectric sensor comprises the photoelectric sensor as claimed in any one of claims 1 to 10, wherein the photoelectric detection device obtains relevant information by sensing the electrical signal generated in response to the light signal received by the photoelectric sensor.

12. An electronic device, characterized in that: The electronic device comprises the photoelectric detection device as claimed in claim 11, and is used to perform corresponding functions according to the relevant information obtained by sensing the electrical signal by the photoelectric detection device.

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