WO2022011701A1

WO2022011701A1 - Single photon avalanche diode and manufacturing method therefor, and photon detection device and system

Info

Publication number: WO2022011701A1
Application number: PCT/CN2020/102783
Authority: WO
Inventors: 杨玉怀; 高桥秀和; 何志宏; 谢承志
Original assignee: 华为技术有限公司
Priority date: 2020-07-17
Filing date: 2020-07-17
Publication date: 2022-01-20
Also published as: CN115428152A

Abstract

Provided are a single photon avalanche diode and a manufacturing method therefor, and a photon detection device and a system. A first doped structure is formed on a horizontal surface and a side wall of one side of a second doped structure; adjacent areas of the first doped structure and the second doped structure are used for forming an avalanche area; and high field areas of adjacent corner areas of the second doped structure and the first doped structure are more likely to form an avalanche area, that is, an avalanche effect occurs at edge areas of the second doped structure and the first doped structure, and therefore, the probability of generating an avalanche effect is relatively high. Moreover, a covering material can provide an electric field that causes photons in a first doped material layer to move from an edge to the center, thereby facilitating the movement of photo-generated carriers in the first doped material layer to an avalanche area, and thus improving the charge collection efficiency to some extent, so that the device has a relatively high quantum efficiency, and thus can have a relatively high photon detection efficiency.

Description

A single photon avalanche diode and its manufacturing method, light detection device and system

technical field

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, a light detection device and a system.

Background technique

At present, photodetectors are used in many scenarios. The photodetector can receive optical signals, and the optical signals excite photoelectrons inside the photodetector and are collected, that is, the photodetector can generate corresponding electrical signals based on the optical signals. Realize the conversion from optical signal to electrical signal.

For example, in a lidar (light detection and ranging, Lidar) system, the object to be measured can be detected by means of time of flight (ToF), specifically, a laser signal is emitted by the radar transmitting system, and the laser signal is transmitted through the After the object to be measured is reflected, it is received by the photodetector, and the flight (round-trip) time of the laser signal is obtained by using the emission time and reception time of the laser signal, so that the distance between the lidar system and the object to be measured (that is, the distance of the object to be measured) can be determined. depth information), and then obtain the position information of the object to be measured. Lidar systems can be used in vehicles. With the continuous evolution of automotive autonomous driving technology, the demand for autonomous driving levels continues to increase, and the demand for vehicle perception capabilities continues to increase. Therefore, higher performance photodetectors in lidar systems are required. . In addition, photodetectors can also be installed in other terminals and wearable devices with photoelectric conversion functions.

The single photon avalanche diode (SPAD) is a component of a photodetector, and its working principle is that the photogenerated carriers (electron-hole pairs) generated by the photoelectric effect under the action of the optical signal, at high The electric field region (the reverse voltage of the PN junction) is rapidly accelerated when moving, and one or more collisions may occur during the movement. Through the collision ionization effect, secondary and tertiary new electron-hole pairs are generated, resulting in an avalanche multiplication effect, which makes the load The number of carriers increases rapidly, resulting in a relatively large photogenerated current. Therefore, single-photon avalanche diodes can detect very weak photons (on the order of single photons), sample and calculate the light field of the imaging target in time and space.

Single-photon avalanche diode is the basic device of many optoelectronic devices, and its performance affects the performance of optoelectronic devices. For example, in direct time of flight (DToF) systems, the responsiveness of single-photon avalanche diodes to photons, that is, photon detection efficiency (PDE), is critical to the performance of DToF systems. The light detection efficiency of single-photon avalanche diodes is low. tend to be lower. Therefore, in order to achieve better performance of optoelectronic devices, it is urgent to improve the performance of single-photon avalanche diodes.

SUMMARY OF THE INVENTION

In view of this, a first aspect of the present application provides a single-photon avalanche diode and a method for manufacturing the same, a light detection device and a system, which can improve light detection efficiency.

In a first aspect of the embodiments of the present application, a single-photon avalanche diode is provided, including a first doping material layer, a second doping structure, a first doping structure and a cover material; wherein the first doping material layer and The second doping structure is stacked in the longitudinal direction, the cross section of the second doping structure is smaller than that of the first doping material layer, the doping types of the first doping material layer and the second doping structure are the same, and the second doping structure is the same. The doping concentration of the structure is higher than that of the first doping material layer, the first doping structure covers the surface of the second doping structure facing the first doping material layer and covers the sidewall of the second doping structure, the first doping structure The doping type is opposite to that of the second doping structure. The region adjacent to the first doping structure and the second doping structure is used to form an avalanche region, and a covering material covers the surface of the first doping material layer. for providing an electric field for moving the multiples in the first doped material layer from the edge to the center.

That is to say, in the embodiment of the present application, the first doping structure is formed on one side of the horizontal surface and the sidewall of the second doping structure, and the region adjacent to the first doping structure and the second doping structure is used for forming Avalanche region, and the high field region of the corner region adjacent to the second doping structure and the first doping structure is more likely to form an avalanche region, that is, the avalanche effect occurs in the edge region of the second doping structure and the first doping structure. , so the probability of avalanche effect is high, and the cover material can provide an electric field that makes the multiple carriers in the first doped material layer move from the edge to the center, which is beneficial to the photogenerated carriers in the first doped material layer to the avalanche region. Therefore, the charge collection efficiency is improved to a certain extent, so the device has a high quantum efficiency, which can have a high photodetection efficiency.

As a possible implementation manner, the single-photon avalanche diode further includes a third doping structure;

When the first doping structure covers a part of the sidewall of the second doping structure that is close to the first doping material layer, the third doping structure is located on an unoccupied portion of the second doping structure. Part of the sidewall covered by the first doping structure, or the third doping structure is located between the second doping material layer and the third doping material layer, and the second doping structure the part of the sidewall not covered by the first doping structure;

The doping type of the third doping structure is the same as that of the second doping structure, and the doping concentration is lower than that of the second doping structure.

In this embodiment of the present application, a third doping structure may be formed to cover a part of the sidewall of the second doping structure away from the first doping material layer, and the doping type of the third doping structure is consistent with the second doping structure , and the doping concentration is lower than that of the second doping structure, so that when a covering material is formed on the surface of the first doping material layer where the second doping structure is formed, the third doping structure can be formed with the second doping structure The sidewalls of the second doping structure can be used as a buffer layer between the second doping structure and the cover material, thereby reducing the surface potential of the device plane formed by the second doping structure and the cover material, and reducing the dark current at the device plane.

As a possible implementation manner, the first doping structure extends longitudinally through the first doping material layer.

In the embodiment of the present application, the first doping structure may vertically penetrate the first doping material layer, so that the electric field generated by the first doping structure can keep the photo-generated carriers in the first doping material layer away from the first doping structure , so that the photogenerated carriers are concentrated to the central position between the first doping structure and the filling material, thereby improving the quantum efficiency.

As a possible implementation manner, the covering material is a fourth doping structure and/or a dielectric layer, and the dielectric layer is charged; the doping type of the fourth doping structure is the same as that of the first doping In contrast to the material layer, the charge type of the dielectric layer is the same as the charge type of the polytrons in the first doped material layer.

In this embodiment of the present application, the cover material may be a third doping structure and/or a dielectric layer, and the dielectric layer may be charged, so that the electric field generated by the third doping material structure and/or the dielectric layer can be used to promote the charge carriers to The center movement of the first doped material layer improves the charge collection efficiency.

As a possible implementation manner, the covering material is connected to the first lead end, and the first lead end and the second doping structure are used to connect different bias voltages respectively.

In this embodiment of the present application, the cover material can be connected to the first lead-out terminal, and the first lead-out terminal can be connected to the second doping structure with different bias voltages respectively, so as to provide a control voltage for the single-photon avalanche diode while promoting charge collection .

As a possible implementation manner, the second doping structure is located in the middle of the first doping material layer, or the second doping structure is disposed along the edge of the first doping material layer, or The second doping structure is located at the top corner of the first doping material layer.

In the embodiment of the present application, the second doping structure may be located at different positions of the first doping material layer, so that the structure of the single-photon avalanche diode is different, and is more adaptable to different scenarios.

As a possible implementation manner, the single-photon avalanche diode further includes a substrate;

A first doping material layer and a second doping structure are sequentially arranged on the substrate from bottom to top.

In the embodiment of the present application, the single-photon avalanche diode can be formed in a front-illuminated light detection device, and the substrate can be sequentially provided with a first doping material layer and a second doping structure from bottom to top, which is beneficial to the second doping connection of heterostructures.

A second doping structure and a first doping material layer are sequentially arranged on the substrate from bottom to top.

In this embodiment of the present application, the single-photon avalanche diode may be formed in a back-illuminated light detection device, and the substrate may be provided with a second doping structure and a first doping material layer in sequence from bottom to top, so that light can be The first doping material layer is directly irradiated from top to bottom without being blocked, which is beneficial to improve the light absorption efficiency.

As a possible implementation manner, the single-photon avalanche diode further includes a microlens layer;

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

In this embodiment of the present application, the single-photon avalanche diode may further include a microlens layer, the microlens layer may be located on a surface away from the substrate, and the microlens layer may be focused on the edge of the first doping material layer and the second doping structure In between, the light can pass through the microlens layer to reach the first doping material layer and be focused, thereby improving the light conversion efficiency.

As a possible implementation manner, the microlens layer is a microlens arranged in an array, and the microlens includes a convex lens and/or a Fresnel lens.

In the embodiment of the present application, the microlens layer may be microlenses arranged in an array, and the microlenses may be convex lenses and/or Fresnel lenses, so as to realize the focusing of the light beam, wherein the Fresnel lens and the convex lens can achieve the same focusing effect At the same time, it can have a smaller vertical size, which is beneficial to reduce the size of the device.

As a possible implementation manner, the single-photon avalanche diode further includes an inverted pyramid structure; the inverted pyramid structure is located on a side away from the substrate.

In the embodiment of the present application, the single-photon avalanche diode may further include an inverted pyramid structure, the inverted pyramid structure may be located on a side away from the substrate, and the inverted pyramid structure has a surface that is not parallel to the surface of the substrate. When the light beam passes through the inverted pyramid structure It will be refracted, so the incident light beam is no longer just a longitudinal beam, but is relatively inclined, so the transmission path length of the beam in the first doping material layer can be increased, and the possibility of optical excitation can be improved. properties and improve the light conversion efficiency.

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

provide a substrate;

The second doping structure, the first doping structure and the first doping material layer are sequentially formed on the substrate from bottom to top; or, the first doping material layer, a first doping structure and a second doping structure;

Wherein, the cross section of the second doping structure is smaller than that of the first doping material layer; the doping types of the first doping material layer and the second doping structure are the same, and the second doping structure is of the same doping type. The doping concentration of the doping structure is higher than that of the first doping material layer; the first doping structure covers the surface of the second doping structure facing the first doping material layer, and covers the second doping material layer sidewalls of the doping structure; the doping type of the first doping structure is opposite to that of the second doping structure, and the region adjacent to the first doping structure and the second doping structure is used for an avalanche region is formed; a covering material is formed on the surface of the first doping material layer, which is used for providing an electric field for moving the multi-subs in the first doping material layer from the edge to the center.

As a possible implementation manner, the method further includes:

forming a third doping structure;

As a possible implementation manner, the method further includes a microlens layer;

As a possible implementation manner, the method further includes an inverted pyramid structure; the inverted pyramid structure is located on a side away from the substrate.

In a third aspect of the embodiments of the present application, a photodetector device is provided, including a plurality of photodetection units; the photodetection units include a logic circuit layer and the single-photon avalanche provided in the first aspect of the embodiments of the present application a diode; the logic circuit layer is electrically connected to the single-photon avalanche diode.

As a possible implementation manner, isolation trenches are used to isolate the single-photon avalanche diodes in different detection units.

As a possible implementation manner, the isolation trench is filled with insulating material; or the sidewall of the isolation trench is formed with a dielectric layer, and the isolation trench is further filled with a metal filling layer.

In a fourth aspect of the embodiments of the present application, a light detection system is provided, including a light emitting device and the light detection device provided in the third aspect of the embodiments of the present application;

The light emitting device is used for emitting light signals to the object to be measured;

The light detection device is used for generating an avalanche current based on the light signal reflected by the object to be tested.

As can be seen from the above technical solutions, the embodiments of the present application have the following advantages:

Embodiments of the present application provide a single-photon avalanche diode, a manufacturing method thereof, a light detection device, and a system, wherein the single-photon avalanche diode includes a first doping material layer, a second doping structure, a first doping structure, and a covering material , wherein the first doping material layer and the second doping structure are stacked in the longitudinal direction, and the cross section of the second doping structure is smaller than the first doping material layer, the first doping material layer and the second doping structure doping The impurity types are consistent, the doping concentration of the second doping structure is higher than that of the first doping material layer, the first doping structure is located between the second doping structure and the first doping material layer, and covers the second doping structure The sidewall of the doping structure, the doping type of the first doping structure is opposite to that of the second doping structure, and the adjacent regions of the first doping structure and the second doping structure are used to form an avalanche region, and the cover material is formed On the surface of the first doping material layer, the electric field is used for providing an electric field for moving the multi-subs in the first doping material layer from the edge to the center.

Description of drawings

In order to clearly understand the specific embodiments of the present application, the accompanying drawings used in describing the specific embodiments of the present application will be briefly described below. Obviously, these drawings are only some embodiments of the present application.

FIG. 1 is a schematic structural diagram of a current single-photon avalanche diode;

2 is a schematic structural diagram of a light detection system provided by an embodiment of the present application;

3 is a schematic structural diagram of a light detection unit according to an embodiment of the present application;

4 is a schematic structural diagram of a single-photon avalanche diode according to an embodiment of the present application;

5 is a schematic diagram of another single-photon avalanche diode provided by an embodiment of the present application;

FIG. 6 is a schematic projection diagram of the second doping structure and the first doping structure in a horizontal plane according to an embodiment of the present application;

7 is a schematic diagram of an equipotential line provided by an embodiment of the present application;

8 is a schematic structural diagram of another single-photon avalanche diode provided by an embodiment of the present application;

9 is a schematic structural diagram of yet another single-photon avalanche diode in an embodiment of the present application;

Fig. 10 is the projection schematic diagram of each component in the horizontal plane in Fig. 9;

11 is a schematic structural diagram of another single-photon avalanche diode provided by an embodiment of the present application;

12 is a schematic structural diagram of yet another single-photon avalanche diode provided by an embodiment of the application;

FIG. 13 is a flowchart of a method for manufacturing a single-photon avalanche diode according to an embodiment of the present application.

detailed description

Embodiments of the present application provide a semiconductor device, a manufacturing method thereof, a light detection device and a system, which can improve light detection efficiency.

The terms "first", "second", "third", "fourth", etc. (if any) in the description and claims of this application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It is to be understood that data so used may be interchanged under appropriate circumstances so that the embodiments described herein can be practiced in sequences other than those illustrated or described herein. Furthermore, the terms "comprising" and "having" and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those expressly listed Rather, those steps or units may include other steps or units not expressly listed or inherent to these processes, methods, products or devices.

The present application will be described in detail with reference to the schematic diagrams. When describing the embodiments of the present application in detail, for the convenience of explanation, the cross-sectional views showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the application here. scope of protection. In addition, the three-dimensional spatial dimensions of length, width and depth should be included in the actual production.

At present, the single-photon avalanche diode is used as a component of a photodetector. Its working principle is to generate photo-generated carriers under the action of optical signals through the photoelectric effect, which are rapidly accelerated when moving in a high electric field region, and may occur during the movement. One or more collisions generate secondary and tertiary new electron-hole pairs through the impact ionization effect, resulting in an avalanche multiplication effect, which rapidly increases the number of carriers, thereby generating a relatively large photo-generated current.

After research, the inventor found that the light detection efficiency of a single-photon avalanche diode is determined by its quantum efficiency for target photons and its own avalanche probability, and the quantum efficiency of a single-photon avalanche diode for target photons is usually equal to its high field region. There is a trade-off between the quantum efficiency and avalanche probability of current single-photon avalanche diodes, and the two cannot be optimized at the same time, resulting in limited light detection efficiency.

Specifically, the current single-photon avalanche diode utilizes the avalanche breakdown of the PN junction, which may occur at the edge or the center flat region of the PN junction. If the avalanche breakdown occurs at the edge, the avalanche probability is high, but high The field area is small. If the avalanche breakdown occurs in the central flat area, the high field area is larger, but the avalanche probability is low.

Referring to FIG. 1 , which is a schematic diagram of the structure of a current single-photon avalanche diode, an N+ well region is arranged on the upper surface of the P-type well, and the contact region between the P-type well and the N+ well region serves as a high-field region, and the avalanche effect also occurs. Generally speaking, the avalanche effect will occur at the edge position first, and it is obvious that the quantum efficiency is low at this time. Therefore, in order to ensure a large enough high field area to achieve high quantum efficiency, it is possible to design a N+ well area around the Protect the ring N-well to avoid breakdown of the single-photon avalanche diode at the edge of the PN junction, so as to use the central flat region of the PN junction for avalanche. The size of the central flat region is relatively large, and the photogenerated carriers generated in the P-type well There is a high probability of moving to the central flat area, resulting in an avalanche effect in the central flat area. Wherein, the upper surface of the P-type well may also be provided with a P+ well region, and the P+ well region and the N+ well region may be biased to promote the occurrence of the avalanche effect.

Based on the above technical problems, embodiments of the present application provide a single-photon avalanche diode, a method for manufacturing the same, a light detection device, and a system, wherein the single-photon avalanche diode may include a first doping material layer, a second doping structure, a A doped structure and a cover material, wherein 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 the first doped material layer, the first doped material layer and the The doping types of the second doping structure are the same, the doping concentration of the second doping structure is higher than that of the first doping material layer, and the first doping structure is located between the second doping structure and the first doping material layer , and cover the sidewall of the second doping structure, the doping type of the first doping structure is opposite to that of the second doping structure, and the adjacent areas of the first doping structure and the second doping structure are used for An avalanche region is formed, and a covering material is formed on the surface of the first doping material layer, and is used for providing an electric field for moving the multi-subs in the first doping material layer from the edge to the center.

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

Referring to FIG. 2, which is a schematic structural diagram of a light detection system provided in an embodiment of the present application, the light detection system may include a light emission device and a light detection device, wherein the light emission device is used to emit light signals to the object to be measured, The light detection device can be used to generate an avalanche current based on the light signal reflected by the object to be tested. The time of flight of the optical signal can be determined by using the time point when the optical signal is emitted to the object to be measured and the time point when the avalanche current is generated, so the distance between the object to be measured and the optical detection system can be calculated.

The light emitting device can be a laser array, and there can be a collimating lens between the light emitting device and the object to be measured; the light detection device can include a plurality of light detection units, the light detection units can be arranged in an array, and there can be a Filters that transmit light of specified wavelengths, such as infrared light.

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

In the isolation trench, insulating materials can be filled to realize the isolation of different single-photon avalanche diodes; in the isolation trench, a dielectric layer can also be formed on the sidewall, and then the isolation trench can be filled with metal fillers , the isolation of different single-photon avalanche diodes can also be achieved. The dielectric layer may be a high dielectric constant (high K) material, such as Al ₂ O ₃ , TaO, HfO, etc., and the metal filling layer may be metal tungsten, for example.

The insulating material or dielectric layer can reduce the dark count of the single-photon avalanche diode, that is, reduce the avalanche current generated in the absence of an optical signal, and can reduce the leakage of the single-photon avalanche diode at the same time. The metal filling layer is usually an opaque material, which can reduce the interference of optical signals between different single-photon avalanche diodes.

Referring to FIG. 3, a schematic structural diagram of a light detection unit provided in an embodiment of the present application, wherein the light detection unit may include a logic circuit layer and a single-photon avalanche diode, and the logic circuit layer may include an image signal processor (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 of the avalanche current. , the photogenerated carriers move and amplify under the action of the electric field to obtain the avalanche current.

The logic circuit layer and the single-photon avalanche diode can be arranged on different layers of the same substrate. For example, the logic circuit layer can be arranged between the substrate and the single-photon avalanche diode to form a back-illuminated structure of the light detection device, as shown in FIG. 3B , The logic circuit layer can also be arranged on the substrate, and is arranged on the same layer as the single-photon avalanche diode thereon to form an orthographic structure of the light detection device, as shown in FIG.

The logic circuit layer may further include a control unit, and the control unit may 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 in different layers.

The light emitting device may also be provided with a control circuit for controlling the light emitting device to emit light signals.

The single-photon avalanche diode provided by the embodiments of the present application will be introduced below with reference to the accompanying drawings.

Referring to FIG. 4 , which is a schematic structural diagram of a single-photon avalanche diode according to an embodiment of the present application, the single-photon avalanche diode may include a first doping material layer 110 , a second doping structure 120 and a first doping structure.

The first doping material layer 110 and the second doping structure 120 may be stacked in the longitudinal direction, and the cross section of the second doping structure 120 may be smaller than the first doping material layer 110. Of course, the first doping material layer 110 may be located in the The top of the second doping structure 120 may also be located below the second doping structure 120 . In the figure, the second doping structure 120 is above the first doping material layer 110 as an example for illustration. The doping types of the first doping material layer 110 and the second doping structure 120 are the same, for example, both are P-type doping or both are N-type doping, and the doping concentration of the second doping structure 120 is higher than that of the first doping Doping concentration of the impurity material layer 110 .

For ease of description, in the embodiments of the present application, different doping may be classified into heavy doping, doping, and light doping according to the level of doping concentration, so as to correspond to different doping concentration ranges respectively, wherein the heavy doping may be It is 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 doping material layer 110 may be shallowly doped, the doping type may be represented by P- or N-, the second doping structure 120 may be heavily doped, and the doping type may be represented by P+ or N+.

The cross section of the first doping material layer 110 may be polygonal, such as a rectangle, a triangle, a hexagon, etc. The second doping structure 120 may be located in the middle of the first doping material layer 110, or may be along the first doping material layer 110. The edge of the dopant material layer may be disposed at the top corner of the first dopant material layer.

In this embodiment of the present application, the single-photon avalanche diode may further include a first doping structure, and the first doping structure may cover the surface of the second doping structure 120 facing the first doping material layer 110 and cover the second doping structure The sidewalls of 120, that is to say, when the first doping material layer 110 is located above the second doping structure 120, the first doping structure may be located on the upper surface and sidewalls of the second doping structure 120. When a doping material layer 110 is located under the second doping structure 120 , the first doping structure may be located on the lower surface and sidewalls of the second doping structure 120 . The doping type of the first doping structure is opposite to that of the first doping material layer 110 , and the doping types of the first doping material layer 110 and the second doping structure 120 are the same, so the doping type of the first doping structure is the same Different from the second doping structure 120 and the first doping material layer 110 . In this way, the first doping material layer 110, the first doping structure and the second doping structure 120 can form a PNP or NPN structure, which is easily formed in the adjacent corner regions of the second doping structure 120 and the first doping structure In the avalanche region 122 , the carriers can enter the second doping structure 120 through the first doping structure in the corner region, wherein the size of the avalanche region 122 is determined according to the actual situation, and the drawing is only one example.

Specifically, the first doping structure may include a first part 111 and a second part 112 that are connected to each other, the first part 111 extends longitudinally in the first doping material layer 110 and is opposite to the second doping structure 120 , and the second part 112 covers the sidewall of the second doping structure 120 and the corner region formed by the surface of the second doping structure 120 facing the first doping material layer 110 .

The second portion 112 in the first doping structure may cover the entire sidewall of the second doping structure 120, or may cover only a portion of the sidewall of the second doping structure 120 close to the first doping material layer 110, or may cover the sidewall of the second doping structure 120. One sidewall, or multiple sidewalls, may cover the entire horizontal surface of the second doping structure 120 near the first doping material layer 110, or only cover the second doping structure 120 near the first doping material layer 110. The edge region of the horizontal surface of the miscellaneous material layer 110 .

That is to say, the second portion 112 of the first doping structure may have a groove in which the second doping structure 120 is embedded, and the groove may be a penetrating groove or a non-penetrating groove. groove. When the second part 112 of the first doping structure includes a through groove, the first part 111 of the first doping structure can be embedded in the groove of the second part 112 so as to be connected with the second part 112. In this case, the first The dimension of the second portion 112 of a doping structure in the horizontal plane is smaller than that of the first portion 111; when the second portion 112 of the first doping structure includes a non-penetrating groove, the first portion 111 of the first doping structure may The side of a doping structure away from the second doping structure 120 is connected to the second part 112 of the first doping structure. At this time, the dimension of the second part 112 of the first doping structure in the horizontal plane may be smaller than that of the first part 111, which can also be equal to the first part 111, or larger than the first part 111.

The longitudinal extension length of the first portion 111 in the first doping structure can be determined according to the actual situation, for example, it can extend to the middle of the first doping material layer 110, or it can longitudinally penetrate the first doping material layer 110, referring to FIG. 4 . shown. The doping concentrations of the first portion 111 and the second portion 112 in the first doping structure may or may not be consistent.

It should be noted that the doping type of the first portion 111 in the first doping structure is inconsistent with the doping type of the first doping material layer 110, so the electric field inside the first doping material layer 110 will be changed, so that the first doping material layer 110 will be changed. The photo-generated carriers in 110 move in a direction away from the first doping structure 111 , which is favorable for the photo-generated carriers to move to the position of the avalanche region, which is favorable for carrier collection. And the longer the longitudinal extension of the first part 111 is, the more favorable it is for the movement of carriers.

In this embodiment of the present application, a voltage may be applied to the second doping structure 120 and the first doping material layer 110 so that there is a voltage difference between the two. The second doping structure 120 can be used as a second lead-out terminal, the first doping material layer 110 can be connected 143 to the first lead-out end, and the first lead-out end 143 and the second lead-out terminal can be used to apply a deviation to the single-photon avalanche diode, thereby The working state of the single-photon avalanche diode is controlled, for example, by setting the bias voltage of the first terminal 143 and the second terminal, so that the single-photon avalanche diode works in the Geiger mode, so that the avalanche effect occurs under the illumination of light. The avalanche current can also be detected by using the second doping structure 120, so as to analyze the avalanche current, for example, using the avalanche current to analyze the optical signal causing the avalanche current.

For example, referring to FIG. 5 , which is a schematic diagram of another single-photon avalanche diode provided by an embodiment of the present application, wherein FIG. 5A is an NPN structure, that is, the doping type of the first doping material layer 110 is N- , the doping type of the first doping structure is P, the doping type of the second doping structure 120 is N+, and the majority of electrons in the first doping material layer 110 are electrons, so the photogenerated carriers are also basically 5B is a PNP structure, that is, the doping type of the first doping material layer 110 is P-, the doping type of the first doping structure is N, the doping type of the second doping structure 120 is P+, and the doping type of the second doping structure 120 is P+. Many carriers in a doped material layer 110 are holes, so the photogenerated carriers are basically holes.

Specifically, the second doping structure 120 may be represented as an ellipse, a circle, a polygon, etc. in the lateral direction. Correspondingly, the second portion 112 of the first doping structure may be embodied as an elliptical ring, a circular ring, a Polygon rings, etc. Referring to FIG. 6 , which is a schematic diagram of the projection of the second doping structure and the first doping structure in the horizontal plane in the embodiment of the present application, as shown in FIG. 6A , the second doping structure 120 forms a circle in the lateral direction, and the first doping structure 120 A doping structure appears as a circular ring in the lateral direction; with reference to FIG. 6B , the second doping structure 120 forms a rectangle in the lateral direction, and the first doping structure appears as a rectangular ring in the lateral direction, wherein the rectangular ring may include corners, Rounded or chamfered corners; as shown in FIG. 6C , the second doping structure 120 may form a triangle in the lateral direction, and the first doping structure may be a triangular ring in the lateral direction, wherein the triangular ring may include corners, rounded corners or beveled corners Cut corners; as shown in FIG. 6D , the second doping structure 120 may form a hexagon in the lateral direction, and the first doping structure may be a hexagonal ring in the lateral direction, wherein the hexagonal ring may include corners, rounded corners or chamfered corners.

In this embodiment of the present application, the single-photon avalanche diode may further include a covering material, and the covering material is formed on the surface of the first doping material layer 110 . Specifically, the covering material may include a covering material formed on the first doping material layer 110 away from the second doping material layer 110 . The first material 1411 of the surface of the heterostructure 120 , and/or the second material 1412 of the sidewall of the first doped material layer 110 , and/or the third material 1413 of the sidewall of the second doped structure 120 . The covering material can also provide an electric field for moving the carriers in the first doping material layer 110 from the edge to the center, so the covering material can promote the movement of carriers from the edge to the center, thereby improving the charge collection efficiency. The first doped material layer 110 can be connected to the first terminal by using a covering material, so as to apply a bias voltage to the single-photon avalanche diode.

Referring to FIG. 7 , which is a schematic diagram of an equipotential line provided by an embodiment of the present application, specifically, a schematic diagram of an equipotential line inside the single-photon avalanche diode shown in FIG. 5A , wherein the upper center position is the second doping The position of the structure 120, the lower center position is the position of the first part 111 of the first doping structure, and the covering material includes the first material, the second material and the third material. It can be seen from the figure that the equipotential lines form a symmetrical structure, The equipotential lines go inward from the outer layer, and the potential gradually increases, so the direction of the electric field lines is directed from the second doping structure 120 to the center position of the cover material and the first part 111 of the first doping structure, and then from the center position to the cover material and the first part 111 of the first doping structure (the opposite direction of the dashed arrow in the figure), so the electrons in the first doped material layer move against the direction of the electric field line, referring to the direction of the dashed arrow in the figure, so as to dope the second Structure 120 moves.

The cover material may be a fourth doping structure, wherein the doping type of the fourth doping structure is opposite to the doping type of the first doping material layer 110 , for example, the doping type of the first doping material layer 110 is N -, the doping type of the fourth doping structure can be P, at this time, the electric field direction is directed from the first doping material layer 110 to the fourth doping structure, so the electrons in the first doping material layer 110 act as multiple electrons, The electrons at the edge move to the middle of the first doping material layer 110 under the action of the electric field generated by the fourth doping structure. The doping type of the first doping structure is opposite to that of the first doping material layer 110 , when the doping type of the first doping material layer 110 is N-, the doping type of the first doping structure can also be P, at this time, the direction of the electric field is directed from the first doping material layer 110 to the first doping structure, and the electrons around the first doping structure will be far away from the first doping structure under the action of the electric field. Therefore, the final electrons will move towards the first doping structure. Aggregation between a doped structure and a fourth doped structure.

The cover material may also be a dielectric layer, the dielectric layer has charges, and the charging type of the dielectric layer is the same as the charging type of the multi-subs in the first doping material layer 110 , for example, the doping type of the first doping material layer 110 The type is N-, in which electrons are multi-subs, the dielectric layer can be negatively charged, and an electric field directed from the first doping material layer 110 to the dielectric layer is generated. Therefore, under the action of the electric field generated by the charged dielectric layer, the dielectric layer is located at the edge position The electrons in the first dopant material layer 110 move toward the middle of the first dopant material layer 110 . The electric field generated by the first doping structure drives electrons away from the first doping structure, and the final electrons will gather between the first doping structure and the dielectric layer.

In actual operation, the cover material may also include the fourth doping structure and the dielectric layer at the same time, wherein the dielectric layer may be located outside the fourth doping structure, and the charged dielectric layer may also be located on the same layer as the fourth doping structure. For example, the first material 1411 located on the surface of the first doping material layer 110 away from the second doping structure 120 is the fourth doping structure, and the first doping material layer 110 is provided with the second doping structure The third material 1413 on the surface of 120 and the second material 1412 on the sidewall of the first doping material layer 110 are dielectric layers, or, the first material 1411 and the second material 1412 are dielectric layers, and the third material 1413 is The third doping structure.

The cover material may surround the first doping material layer 110, and the setting position may be on the surface of the first doping material layer 110. When a plurality of light detection units are distributed in an array, the first doping material layer 110 in the single-photon avalanche diode also For array distribution, the first dopant material layers 110 in different single-photon avalanche diodes can be separated by longitudinal isolation trenches, and the capping material is located on the surface of the first dopant material layer and thus adjacent to the isolation trenches, At this time, the covering material may be formed on the inner sidewall of the isolation trench, or may surround the isolation trench. . That is, the fourth doping structure and/or the dielectric layer may form the inner sidewall of the isolation trench 140 , or may be formed on the periphery of the isolation trench 140 .

For example, in the isolation trench 140, a dielectric layer can be formed on the sidewall, and then the isolation trench 140 can be filled with a metal filler 142, and the isolation of different single-photon avalanche diodes can also be realized. The dielectric layer here is a charged dielectric layer, which is formed on the sidewall of the first doping material layer 110. The charged dielectric layer can also provide an electric field for moving the multiple electrons in the first doping 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 be used as a covering material, and can also form a covering material together with the fourth doping structure.

The first doping material layer 110 can be connected to the first lead-out end 143 through the cover material, so in practice, the first lead-out end 143 and the second lead-out end (ie, the second doping structure 120 ) can be arranged on the same layer, It is convenient to bias both. The first lead-out terminal 143 may be a doped material, and its doping type is different from that of the second doping structure 120, and its doping is also heavily doped, which may be represented by P+ or N+. The first lead-out end 143 and the second lead-out end may also be connected with an interconnection line 133, and the interconnection line 133 may be made of a metal material. The connection line 133 can be made of transparent electrode material, so as to improve the transmittance of light. The interconnection lines 133 may be disposed in the capping layer 134, as shown in FIG. 11 .

When the cover material is located on the sidewall of the second doping structure 120, since the cover material and the second doping structure 120 often have opposite types of carriers, the contact surface between the two has a large potential difference. A third doping structure 121 is formed between the second doping structure 120 and the covering material, which can reduce the horizontal surface potential gradient where the second doping structure 120 and the first doping structure are located, thereby reducing leakage.

Therefore, in this embodiment of the present application, the single-photon avalanche diode may further include a third doping structure 121, the doping type of the third doping structure 121 is the same as that of the second doping structure 120, and the doping concentration is lower than that of the second doping structure 121. Heterostructure 120 . When the second portion 112 of the first doping structure is located at a part of the sidewall of the second doping structure 120 close to the first doping material layer 110 , the third doping structure 121 may be located in the second doping structure 120 not covered by the second doping structure 120 . A part of the sidewall covered by a doping structure, at this time, the second doping structure 120 and the first doping structure can be in direct contact. Referring to FIG. 8 , another single photon avalanche provided by this embodiment of the present application is provided. A schematic diagram of the structure of a diode, the existence of the third doping structure 121 can reduce the horizontal surface potential gradient where the second doping structure 120 and the first doping structure are located, and the third doping structure 121 can also be located between the second doping structure 120 and the first doping structure. Between the first doping structures, as a breakdown protection layer between the second doping structure 120 and the first doping structure, of course, the third doping structure 121 may be simultaneously located between the second doping structure 120 and the first doping structure Part of the sidewall covered by the doping structure, and between the second doping structure 120 and the first doping structure, that is, the third doping structure 121 may cover the entire sidewall of the second doping structure 120, and the second doping structure The structure 120 is close to the horizontal surface of the first dopant material layer 110 , as shown with reference to FIG. 4 .

That is to say, the third doping structure 121 may be located on the sidewall of the second doping structure 120, or may be located on the sidewall of the second doping structure 120 and between the second doping structure 120 and the first doping structure, At this time, the presence of the third doping structure 121 will not affect the position of the avalanche region and the avalanche probability between the second doping structure 120 and the first doping structure, and the avalanche region is still located between the first doping structure and the second doping structure. The adjacent corner positions of the doped structures.

The lateral thickness of the third doping structure 121 located on the sidewall of the second doping structure 120 may be determined according to actual conditions. When the third doping structure 121 is located at a part of the sidewall of the second doping structure 120 that is not covered by the first doping structure, the lateral thickness of the third doping structure 121 can be appropriately increased to effectively reduce the second doping structure 120 and the horizontal surface potential gradient where the first doped structure is located.

The cross section of the first doping material layer 110 may be polygonal, such as a rectangle, a triangle, a hexagon, etc. The second doping structure 120 may be located in the middle of the first doping material layer 110, or may be along the first doping material layer 110. The edge of the dopant material layer may be disposed at the top corner of the first dopant material layer. Referring to FIG. 4 , the second doping structure 120 is located in the middle of the first doping material layer 110 . Referring to FIGS. 9 and 10 , the second doping structure 120 may be disposed at the top corner of the first doping material layer position, wherein, FIG. 9 is a schematic structural diagram of another single-photon avalanche diode in the embodiment of the application, and FIG. 10 is a schematic projection diagram of each component in FIG. 9 in the horizontal plane. Specifically, the second doping structure and the first doping structure The heterostructure can be located at the upper right corner of the first doping material layer, the isolation trench 140 separates different first doping material layers, the cover material is formed on the periphery of the isolation trench, and is connected to the first lead-out end 143, the first The cross section of the second doping structure 120 is a quarter circle, and the third doping structure 121 and the first doping structure are quarter circles. In this way, the electric field generated by the cover material makes the first doping material layer 110 The photo-generated carriers generated in the middle move from the edge to the center, and the electric field between the second doping structure 120, the third doping structure 121, the first doping structure and the first doping material layer 110 causes the photo-generated carriers to move toward the center. The second doping structure 120 moves and an avalanche current is formed.

Of course, the second doping structure 120 may also be disposed along one side of the rectangular first doping material layer. In this case, the second doping structure 120 may be a half circle, and the third doping structure 121 and The first doping structure is a half ring, which is not illustrated here.

In this embodiment of the present application, the first doping material layers located in different light detection units may be separated by isolation trenches, and at this time, a bias voltage may also be applied to the metal filling layer 142 in the isolation trench 140, thereby accelerating Collection of photogenerated carriers. Specifically, when the doping type of the first doping material layer 110 is N-, a negative bias voltage may be applied to the metal filling layer 142, and when the doping type of the first doping material layer 110 is P-, it may be The metal fill layer 142 is positively biased.

In this embodiment of the present application, the single-photon avalanche diode may further include a substrate 100, and the second doping structure 120, the first doping structure and the first doping material layer 110 described above may be disposed on the substrate 100, because The photodetection devices are classified into two types: front-illuminated (FSI) and back-illuminated (BSI), so the stacking methods on the substrate 100 are also different. Generally speaking, the light detection device can include a single-photon avalanche diode and a logic circuit layer. In a front-illuminated device, the logic circuit layer can be located on the same layer as the single-photon avalanche diode. Light directly illuminates the single-photon avalanche diode from above, and the logic circuit layer is not It will affect the occlusion of the light beam. In the back-illuminated device, the logic circuit layer is located under the single-photon avalanche diode, and the light directly illuminates the single-photon avalanche diode, and the logic circuit layer will not block the light beam.

Specifically, reference may be made to FIG. 11 , which is a schematic structural diagram of yet another single-photon avalanche diode provided in an embodiment of the present application. Wherein, in the front-illuminated device, as shown in FIG. 11A , in order to facilitate connection, the second doping structure 120 of the single-photon avalanche diode can be disposed upward, and the interconnect layer 133 is disposed above the second doping structure 120, For realizing the interconnection between the single photon avalanche diode and the logic circuit layer, the interconnection layer 133 may be disposed in the dielectric layer 134 . Therefore, light is incident on the first doping material layer 110 from top to bottom, and does not need to pass through the substrate 100 , that is, the substrate 100 can be provided with the first doping material layer 110 , the first doping structure and the In the second doping structure 120, at this time, the interconnection layer 133 on the second doping structure 120 may be a transparent metal material to reduce the absorption of light.

In the back-illuminated device, as shown in FIG. 11B , in order to facilitate connection, the second doping structure 120 of the single-photon avalanche diode can be disposed downward, and the interconnect layer 133 can be disposed below the second doping structure 120 , for realizing the interconnection between the single-photon avalanche diode and the logic circuit layer, the interconnection layer 133 may be arranged in the dielectric layer 134 . The light is directly incident on the first doping material layer 110 from top to bottom, and does not need to pass through the substrate 100 , that is, the substrate 100 can be provided with the second doping structure 120 , the first doping structure and the first doping structure from bottom to top. Doping material layer 110 .

Wherein, the substrate 100 may be an insulating substrate or a semiconductor substrate. When the substrate 100 is a semiconductor substrate, an insulating layer may be formed on the surface of the substrate 100, so as to separate the substrate 100 and other films on it. The layers are separated to avoid the influence of the carrier avalanche current generated by the substrate 100, so the dark count can be reduced. For example, the substrate 100 is an insulator, and the second doping structure 120 , the first doping structure and the third doping structure 121 thereon are doped silicon materials, thereby forming a silicon on insulator (SOI) )structure.

The single-photon avalanche diode in this embodiment of the present application may further include a microlens layer 150. The microlens layer 150 may be located on a surface away from the substrate 100, and the microlens layer 150 may be used to focus the optical signal, thereby Concentrate the optical signal in a location prone to avalanche effects. Referring to FIG. 12 , which is a schematic structural diagram of another single-photon avalanche diode provided by an embodiment of the present application, wherein FIG. 12A is a front-illuminated structure, and the microlens layer 150 is disposed on the second doping structure 120 . Shown as a backside illuminated structure, the microlens layer 150 is disposed on the first doped material layer 110 . In FIG. 11, the substrate 100 is an insulating substrate.

Specifically, the focusing position of the microlens layer 150 is in the middle between the edge of the first doping material layer 110 and the second doping structure 120, so that the light beam can be focused to the first doping structure and the first doping structure 120. The position between the edges of the doping material layer 110 can improve the carrier collection efficiency.

Specifically, the microlens layer may include microlenses arranged in an array, and the microlenses may be convex lenses and/or Fresnel lenses, wherein the Fresnel lenses and the convex lenses can achieve the same focusing effect, and can have smaller The vertical size is conducive to reducing the size of the device. The arrangement position thereof can be determined according to the shape of the second doping structure 120 , and the arrangement quantity thereof can be determined according to the actual situation. On the microlens layer, an anti-reflection layer can also be provided to increase the quantum efficiency of the target light.

In the embodiment of the present application, the single-photon avalanche diode may further include an inverted pyramid structure 151, the inverted pyramid structure 151 may be an inverted pyramid structure array (inverted pyramid array, IPA), and the inverted pyramid structure 151 is located on a side away from the substrate 100, It is used for refraction when the light passes through, thereby changing the transmission direction of the light, so that the light is not only transmitted in the vertical direction in the first doping material layer 110, thus increasing the transmission path of the light and increasing the first doping material layer 110 absorbs light to generate carriers. The structure in the inverted pyramid structure 151 has a plurality of 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 layers above or below it, so that light is refracted and changed when passing through. direction of light transmission. Specifically, the inverted pyramid structure may be obtained by etching and filling the first doping material layer, or may be obtained by etching and filling the cover material.

The inverted pyramid structure 151 may be located between the microlens layer 150 and the film layer below it, so that light is focused and refracted, for example, between the microlens layer 150 and the third material 1413 of the sidewall of the second doping structure 120 , the inverted pyramid structure 151 can be obtained by etching and filling the third material 1413 under it, and a flat layer 152 can be provided on the inverted pyramid structure 151 to facilitate the formation of the upper film layer, as shown in FIG. 12A , Alternatively, the inverted pyramid structure 151 may be located between the microlens layer 150 and the first doping material layer 110, and the inverted pyramid structure 151 may be obtained by etching and filling the first material 1411 under the inverted pyramid structure 151. A planarization layer 152 may be formed, as shown with reference to FIG. 12B.

It should be noted that, in the embodiment of the present application, the inverted pyramid structure 151 is located in the cover material. If the cover material is a charged dielectric layer, the first doping material layer 110 may be etched first to obtain the inverted pyramid structure. If a charged dielectric layer is formed on the inverted pyramid structure, the first doping material layer 110 may not be doped to form a fourth doping structure.

Embodiments of the present application provide a single-photon avalanche diode, including a first doping material layer, a second doping structure, a first doping structure and a cover material, wherein the first doping material layer and the second doping structure are Stacked vertically, the cross section of the second doping structure is smaller than that of the first doping material layer, the doping types of the first doping material layer and the second doping structure are the same, and the doping concentration of the second doping structure is high In the first doping material layer, the first doping structure is located between the second doping structure and the first doping material layer, and covers the sidewall of the second doping structure, the doping of the first doping structure The type is opposite to that of the second doping structure, and a region adjacent to the first doping structure and the second doping structure is used to form an avalanche region, and a cover material is formed on the surface of the first doping material layer to provide the first doping structure. The electric field for the movement of multiples in a layer of doped material from the edge to the center.

Based on the single-photon avalanche diode provided by the above embodiments, an embodiment of the present application further provides a method for manufacturing a single-photon avalanche diode. Referring to FIG. 13 , a method for manufacturing a single-photon avalanche diode provided by an embodiment of the present application is provided. Specifically, the method may include the following steps:

S101, providing a substrate.

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 from other film layers on it and avoid the lining of the substrate. The carrier avalanche current generated at the bottom has an influence, so the dark count can be reduced.

S102, forming a second doping structure, a first doping structure, and a first doping material layer on the substrate sequentially from bottom to top; or, forming a first doping material layer, a first doping material layer, a first doping material layer on the substrate from bottom to top sequentially Doping structure and second doping structure.

The cross section of the second doping structure is smaller than that of the first doping material layer, the doping types of the first doping material layer and the second doping structure are the same, and the doping concentration of the second doping structure is higher than that of the first doping structure Doping material layer, the first doping structure is located between the second doping structure and the first doping material layer, and covers the sidewall of the second doping structure, the doping type of the first doping structure is the same as that of the second doping structure In contrast to the doping structure, a region adjacent to the first doping structure and the second doping structure is used to form an avalanche region, and a covering material is formed on the surface of the first doping material layer, which is used to provide the first doping material layer. The electric field of the many particles moving from the edge to the center.

The first doping material layer, the first doping structure and the second doping structure may be doped silicon materials.

As a possible implementation manner, the second doping structure, the first doping structure and the first doping material layer may be sequentially formed on the substrate from bottom to top. After that, an interconnection layer interconnecting 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 doping structure, thereby forming a light detection unit. Of course, the logic circuit can also be formed in a single-photon avalanche diode. photonic avalanche diodes are formed before.

Specifically, a bulk structure can be formed on the substrate, and the bulk structure is sequentially doped to form a first doping material layer, a third doping material, and a second doping structure. The bulk structure can be an intrinsic layer or a Lightly doped layer. The lightly doped layer may be the bulk structure of the first doped material layer, and the first doped structure and the second doped structure are formed by doping in the bulk structure of the first doped material layer, and the lightly doped layer is also It can be other material layers, and the first doped material layer, the first doped structure and the second doped structure are obtained by doping. Specifically, the first doping material layer, the third doping material, and the second doping structure can also be sequentially formed on the substrate by means of epitaxial growth.

For example, referring to the single-photon avalanche diode shown in FIG. 11A , the bulk structure of the first doping material layer 110 may be formed on the substrate first, where the bulk structure includes the first doping structure and the second doping structure. Structure 120, location of cover material. After that, the bottom of the bulk structure can be counter-doped to obtain the first material 1411 in the covering material on the bottom surface of the first doping material layer 110, and then the sidewalls of the bulk structure can be counter-doped to obtain the first material 1411 located on the bottom surface of the first doping material layer 110. The second material 1412 in the covering material of the sidewall of a doped material layer 110 can be counter-doped in the middle of the bulk structure to obtain the first part 111 and the second part 112 of the first doped structure. Doping is performed on the upper portion of the bulk structure to form the second doping structure 130, and counter-doping is performed to form the third material 1413 in the capping material.

As another possible implementation manner, the second doping structure, the first doping structure and the first doping material layer may be sequentially formed on the substrate from bottom to top. At this time, a logic circuit layer and a dielectric layer covering the logic circuit layer may have been formed on the substrate, and the second doping structure may be formed on the dielectric layer covering the logic circuit layer. Before forming the second doping structure, an interconnection layer interconnected with the logic circuit layer may also be formed, and the interconnection layer is used to connect the second doping structure and the logic circuit layer.

Specifically, a bulk structure can be formed on the substrate, and the bulk structure is sequentially doped to form a second doping structure, a first doping structure, and a first doping material layer. The bulk structure can be an intrinsic layer or a Lightly doped layer. The lightly doped layer can be a first doped material layer, the first doped structure and the second doped structure are formed by doping in the first doped material layer, and the lightly doped layer can also be other material layers, The first doping material layer, the first doping structure and the second doping structure are obtained by doping. Specifically, the second doping structure, the first doping structure and the first doping material layer can also be sequentially formed on the substrate by means of epitaxial growth.

For example, referring to the single-photon avalanche diode shown in FIG. 11B , a bulk structure of the first doping material layer 110 may be formed on the substrate first, where the bulk structure includes the first doping structure and the second doping structure. Structure 120, location of cover material. After that, doping can be performed heavily at the bottom of the bulk structure to form the second doping structure 120, and counter-doping can be performed to form the third material 1413 in the covering material; after that, counter-doping can be performed in the middle of the bulk structure , obtaining the first part 111 and the second part 112 of the first doping structure, and performing counter-doping on the sidewall of the bulk structure to obtain the second material 1412 located in the covering material of the sidewall of the first doping material layer 110; Afterwards, the upper portion of the bulk structure may be counter-doped to obtain the first material 1411 in the capping material on the bottom surface of the first doped material layer 110 .

In this embodiment of the present application, the single-photon avalanche diode may further include a cover material, and the cover material may be formed on the surface of the first doping material layer. Specifically, the cover material may be formed on the surface of the first doping material layer away from the second doping structure. the surface, and/or the sidewalls of the first dopant material layer, and/or the sidewalls of the second dopant material layer. The covering material can also provide an electric field for moving the carriers in the first doping material layer from the edge to the center, so the covering material can promote the movement of carriers from the edge to the center, thereby improving the charge collection efficiency. The first doping material layer can be connected to the first terminal by using a covering material, so as to apply a bias voltage to the single-photon avalanche diode.

The cover material may be a fourth doping structure, wherein the doping type of the fourth doping structure is opposite to the doping type of the first doping material layer, for example, the doping type of the first doping material layer is N-, Then the doping type of the fourth doping structure can be P. At this time, the direction of the electric field is directed from the first doping material layer to the fourth doping structure, so the electrons in the first doping material layer are multi-subs, and the electrons in the edge are in the Under the action of the electric field generated by the fourth doping structure, it moves to the middle of the first doping material layer. And the doping type of the first doping structure is opposite to that of the first doping material layer, when the doping type of the first doping material layer is N-, the doping type of the first doping structure may also be P, At this time, the direction of the electric field is directed from the first doping material layer to the first doping structure, and the electrons around the first doping structure will move away from the first doping structure under the action of the electric field. Therefore, the final electrons will be doped toward the first doping structure. between the structure and the fourth doped structure.

Wherein, the cover material can also be a dielectric layer, the dielectric layer is charged, and the charging type of the dielectric layer is the same as the charging type of the multi-subs in the first doping material layer, for example, the doping type of the first doping material layer is N-, in which electrons act as multi-subs, the dielectric layer can be negatively charged, and an electric field directed from the first doping material layer to the dielectric layer is generated. Electrons in the dopant material layer move toward the middle of the first dopant material layer. The electric field generated by the first doping structure drives electrons away from the first doping structure, and the final electrons will gather between the first doping structure and the dielectric layer.

The cover material can surround the first doping material layer, and its setting position is on the surface of the first doping material layer. When a plurality of light detection units are distributed in an array, the first doping material layer in the single-photon avalanche diode is also distributed in an array. The first dopant material layers in different single-photon avalanche diodes can be separated by longitudinal isolation trenches, and the cover material is located on the surface of the first dopant material layer, so it is adjacent to the isolation trenches. At this time, the cover material It can be formed on the inner sidewall of the isolation trench, or can surround the isolation trench. That is, the fourth doping structure and/or the charged dielectric layer may form the inner sidewall of the isolation trench, or may be formed on the outer periphery of the isolation trench.

The cover material can be formed by doping or epitaxial growth. For example, doping can be performed at the edge of the first doping material layer to obtain a fourth doping structure surrounding the remaining first doping material layer, or the first doping material layer can be etched to form an isolation trench, A charged dielectric layer is epitaxially formed on the sidewalls of the isolation trenches.

In this embodiment of the present application, a third doping structure may also be formed. The doping type of the third doping structure 121 is the same as that of the second doping structure 120 , and the doping concentration is lower than that of the second doping structure 120 . When the second portion 112 of the first doping structure is located at a part of the sidewall of the second doping structure 120 close to the first doping material layer 110 , the third doping structure 121 may be located in the second doping structure 120 not covered by the second doping structure 120 . A part of the sidewall covered by the doping structure, at this time, the second doping structure 120 and the first doping structure can be in direct contact, and the existence of the third doping structure 121 can reduce the amount of the second doping structure 120 and the first doping structure The horizontal surface potential gradient where the doping structure is located, the third doping structure 121 may also be located between the second doping structure 120 and the first doping structure, as the difference between the second doping structure 120 and the first doping structure The breakdown protection layer, of course, the third doping structure 121 may be located at the part of the sidewall of the second doping structure 120 not covered by the first doping structure, and between the second doping structure 120 and the first doping structure at the same time , that is, the third doping structure 121 may cover the entire sidewall of the second doping structure 120 and the horizontal surface of the second doping structure 120 close to the first doping material layer 110 .

That is to say, the third doping structure 121 may be located on the sidewall of the second doping structure 120, or may be located on the sidewall of the second doping structure 120 and between the second doping structure 120 and the first doping structure, At this time, the presence of the third doping structure 121 will not affect the position of the avalanche region and the avalanche probability between the second doping structure 120 and the first doping structure.

In this embodiment of the present application, a microlens layer may also be formed, the microlens layer may be located on a surface away from the substrate, and the microlens layer may be used to focus the optical signal, so that the optical signal is concentrated in the area where the avalanche effect is likely to occur. Location. Specifically, the focal position of the microlens layer overlaps with the projection of the second doping structure on the horizontal plane, so that the light beam can be focused to the position opposite to the second doping structure, thereby improving the carrier collection efficiency. Specifically, the microlens layer may include microlenses arranged in an array, and the microlenses may be convex lenses and/or Fresnel lenses.

The formation method of the microlens layer may be reflow, etching back, or the like. Wherein, the reflow method can be specifically as follows: spin-coating a photosensitive organic material on the surface of the device away from the substrate, and then through exposure, development and heating to reflow, a microlens layer of the photosensitive organic material can be obtained; the etching back can be specifically as follows: A flat layer is deposited on the surface of the device away from the substrate, and a photosensitive organic material is spin-coated on the flat layer, and then a mask layer of the photosensitive organic material is obtained by exposure and development and heating and reflow. The pattern on the organic material is transferred to the flat layer.

In the embodiment of the present application, an inverted pyramid structure can also be formed, and the inverted pyramid structure can be an array of inverted pyramid structures, and the inverted pyramid structure is located on the side away from the substrate, and is used for refraction when light passes through, thereby changing the transmission direction of light , so that the light is not only transmitted in the vertical direction in the first doping material layer, thus increasing the light transmission path and increasing the possibility that the first doping material layer absorbs light to generate carriers. The inverted pyramid structure can be located between the microlens layer and the film layer below it, so that light is focused and refracted. Therefore, the inverted pyramid structure can be formed before forming the microlens layer.

Embodiments of the present application provide a method for manufacturing a single-photon avalanche diode. Specifically, a second doping structure, a first doping structure, and a third doping structure may be sequentially formed on the substrate from bottom to top, or the lower right A third doping structure, a first doping structure and a second doping structure are sequentially formed thereon, wherein the cross section of the second doping structure is smaller than the first doping material layer; the first doping material The doping type of the layer and the second doping structure are consistent, and the doping concentration of the second doping structure is higher than that of the first doping material layer; the first doping structure is located in the second doping structure between the doping structure and the first doping material layer, and covering the sidewall of the second doping structure; the doping type of the first doping structure is opposite to that of the second doping structure, which The adjacent regions are used to form an avalanche region; the surface of the first dopant material layer is formed with a covering material, which is used for providing an electric field for moving the polytrons in the first dopant material layer from the edge to the center.

Each embodiment in this specification is described in a progressive manner, and the same and similar parts between the various embodiments may be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the method embodiment, since it is basically similar to the structural embodiment, the description is relatively simple, and for related parts, please refer to the partial description of the structural embodiment.

The above is a specific implementation manner of the application. It should be understood that the above-mentioned 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 above-mentioned embodiments, those of ordinary skill in the art should understand that: it can still be used for The technical solutions described in the foregoing embodiments are modified, or some technical features thereof are equivalently replaced; 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

A single-photon avalanche diode is characterized by comprising a first doping material layer, a second doping structure, a first doping structure and a covering material;

The first doping material layer and the second doping structure are stacked in the longitudinal direction, and the cross section of the second doping structure is smaller than the first doping material layer; the first doping material layer It is consistent with the doping type of the second doping structure, and the doping concentration of the second doping structure is higher than that of the first doping material layer;

The first doping structure covers the surface of the second doping structure facing the first doping material layer, and covers the sidewall of the second doping structure; the doping of the first doping structure The type is opposite to that of the second doping structure, and a region adjacent to the first doping structure and the second doping structure is used to form an avalanche region;

The cover material covers the surface of the first dopant material layer, and is used for providing an electric field for moving the multi-subs in the first dopant material layer from the edge to the center.
The single-photon avalanche diode according to claim 1, further comprising a third doping structure;

When the first doping structure covers a part of the sidewall of the second doping structure that is close to the first doping material layer, the third doping structure is located on an unoccupied portion of the second doping structure. Part of the sidewall covered by the first doping structure, or the third doping structure is located between the second doping material layer and the third doping material layer, and the second doping structure the part of the sidewall not covered by the first doping structure;

The doping type of the third doping structure is the same as that of the second doping structure, and the doping concentration is lower than that of the second doping structure.
The single-photon avalanche diode according to claim 1, wherein the first doping structure penetrates the first doping material layer longitudinally.
The single-photon avalanche diode according to claim 1, wherein the covering material is a fourth doping structure and/or a dielectric layer, and the dielectric layer is charged; the doping of the fourth doping structure The type is opposite to that of the first doped material layer, and the charged type of the dielectric layer is the same as the charged type of the polytrons in the first doped material layer.
The single-photon avalanche diode according to claim 1, wherein the covering material is connected to a first lead end, and the first lead end and the second doping structure are used to connect different bias voltages respectively.
The single-photon avalanche diode according to claim 1, wherein the second doping structure is located in the middle of the first doping material layer, or the second doping structure is along the first doping material layer. The edge of the dopant material layer is disposed, or the second doping structure is located at the top corner of the first dopant material layer.
The single-photon avalanche diode according to any one of claims 1-6, further comprising a substrate;

A first doping material layer and a second doping structure are sequentially arranged on the substrate from bottom to top.
The single-photon avalanche diode according to any one of claims 1-6, further comprising a substrate;

A second doping structure and a first doping material layer are sequentially arranged on the substrate from bottom to top.
The single-photon avalanche diode according to claim 7 or 8, further comprising a microlens layer;

The microlens layer is located on a surface away from the substrate; the focus of the microlens layer is between the edge of the first doping material layer and the second doping structure.
The single-photon avalanche diode according to claim 9, wherein the microlens layer is a microlens arranged in an array, and the microlens comprises a convex lens and/or a Fresnel lens.
The single-photon avalanche diode according to any one of claims 7-10, further comprising an inverted pyramid structure; the inverted pyramid structure is located on a side away from the substrate.
A method for manufacturing a single-photon avalanche diode, comprising:

provide a substrate;

The second doping structure, the first doping structure and the first doping material layer are sequentially formed on the substrate from bottom to top; or, the first doping material layer, a first doping structure and a second doping structure;

Wherein, the cross section of the second doping structure is smaller than that of the first doping material layer; the doping types of the first doping material layer and the second doping structure are the same, and the second doping structure is of the same doping type. The doping concentration of the doping structure is higher than that of the first doping material layer; the first doping structure covers the surface of the second doping structure facing the first doping material layer, and covers the second doping material layer sidewalls of the doping structure; the doping type of the first doping structure is opposite to that of the second doping structure, and the region adjacent to the first doping structure and the second doping structure is used for an avalanche region is formed; a covering material is formed on the surface of the first doping material layer, which is used for providing an electric field for moving the multi-subs in the first doping material layer from the edge to the center.
The method of claim 12, further comprising:

forming a third doping structure;

When the first doping structure covers a part of the sidewall of the second doping structure that is close to the first doping material layer, the third doping structure is located on an unoccupied portion of the second doping structure. Part of the sidewall covered by the first doping structure, or the third doping structure is located between the second doping material layer and the third doping material layer, and the second doping structure the part of the sidewall not covered by the first doping structure;

The doping type of the third doping structure is the same as that of the second doping structure, and the doping concentration is lower than that of the second doping structure.
13. The method of claim 12, wherein the first doping structure extends longitudinally through the first doping material layer.
The method of claim 12, wherein the second doping structure is located in the middle of the first doping material layer, or the second doping structure is along the first doping material layer , or the second doping structure is located at the top corner of the first doping material layer.
A light detection device, characterized in that it includes a plurality of light detection units, the light detection units include a logic circuit layer and the single-photon avalanche diode according to any one of claims 1-11; the logic circuit layer and all The single-photon avalanche diode is electrically connected.
The light detection device according to claim 16, wherein the single-photon avalanche diodes in different detection units are separated by isolation trenches.
The light detection device according to claim 17, wherein the isolation trench is filled with insulating material; or the sidewall of the isolation trench is formed with a dielectric layer, and the isolation trench is further filled with metal filler Floor.
A light detection system, characterized in that it comprises a light emission device and the light detection device according to any one of claims 16-18;

The light emitting device is used for emitting light signals to the object to be measured;

The light detection device is used for generating an avalanche current based on the light signal reflected by the object to be tested.