CN113270507B - Avalanche photodiode and photomultiplier detector - Google Patents

Abstract

The invention discloses an avalanche photodiode and a photomultiplier detector, relates to the technical field of radiation detection or weak light detection, and aims to solve the problem of low detection efficiency of the detector. The avalanche photodiode comprises a substrate and an incident light anti-reflection layer, wherein the substrate comprises a plurality of doping regions, the doping regions are formed by doping impurity ions into the substrate, and the doping regions comprise a light incident end P-type heavily doped region, an N-type heavily doped region, a P-type doping region and a P-type low doping region. The photomultiplier detector comprises a plurality of avalanche photodiode units, the plurality of avalanche photodiode units are connected in parallel, each avalanche photodiode unit comprises a quenching resistor and an avalanche photodiode related to the technical scheme, and the avalanche photodiodes and the quenching resistors are connected in series. The avalanche photodiode and the photomultiplier detector provided by the invention are used for radiation detection or weak light detection.

Description

A kind of avalanche photodiode and photomultiplier tube detector

technical field

The invention relates to the technical field of radiation detection or weak light detection, in particular to an avalanche photodiode and a photomultiplier tube detector used in radiation detection or weak light detection.

Background technique

Low-light detector technology has always been very important in the fields of high-energy physics, astrophysics, and nuclear medical imaging. At present, the most widely used low-light detector is mainly the photomultiplier tube (PMT). However, due to the disadvantages of large size, high working voltage, high power consumption, easy damage, low detection efficiency limited by photocathode, sensitivity to magnetic field changes, and unsuitability for making large-scale detection arrays, PMT limits its application in many aspects. application. In the early 1990s, Russian scientists first proposed a detector called Silicon Photomultiplier (SiPM), which has attracted great attention from researchers in the field of weak light detection, and has now become a weak light detector. A research hotspot in the field of photodetector technology.

SiPM is an array-type photoelectric conversion device composed of multiple APDs (Avalanche PhotoDiode, avalanche photodiodes) working in Geiger mode. Each avalanche photodiode unit contains a large resistance quenching resistor, and all avalanche photodiode units are connected in parallel. The output, constitutes an area array, forming SiPM. After the SiPM is applied with a reverse bias voltage (generally tens of V), the APD depletion layer of each avalanche photodiode has a very high electric field. After the photons enter the APD, Compton scattering occurs, and the valence electrons of the semiconductor are excited into free electrons. The free electrons generated are accelerated in the electric field, and a large number of secondary electrons are released, that is, electron multiplication is realized through avalanche discharge. At this time, the current in each avalanche photodiode unit circuit suddenly increases, and then an electrical signal is formed at the output terminal. The amount of charge Q output by a single APD does not reflect the number of incident photons, but is only related to the capacitance and over-threshold voltage of the APD. When it is much smaller than the sum of APDs of SiPM, the probability of two or more photons incident on the same APD is very small, which makes SiPM capable of resolving single photons. Within a certain light intensity range, the output charge of SiPM is proportional to the number of incident photons, that is, SiPM has the function of photon counter. It is mainly used in the measurement and detection of rays, industrial automatic control and photometric measurement. When it is used in the infrared band, it is mainly used in missile guidance, infrared thermal imaging and infrared remote sensing. In addition, it can also be applied to the receiving end of the single-photon information carrier of quantum communication, and obtain a true random number to realize the distribution of security keys for quantum secret communication.

The main performance indicators of SiPM are: detection efficiency, dark count rate, gain, etc. Among them, the detection efficiency is the most critical, which directly affects the single-photon detection performance. The photon detection efficiency (PDE) of SiPM is mainly composed of three factors: quantum detection efficiency (QE), fill factor (FF) of the light entrance, and photogenerated carrier triggering avalanche probability (PT), which can be expressed as:

PDE=QE×FF×PT

Among them, the photogenerated carrier trigger avalanche probability (PT) is affected by the device structure, and the fill factor (FF) of the light entrance is mainly affected by the quenching resistance (RQ), the top lead-out electrode and the layout of the isolation structure, and it is difficult to reach 100. %, and the fill factor (FF) of the light entrance decreases as the number of pixels per unit area increases. Therefore, how to improve the detection efficiency of SiPM has become an urgent problem to be solved.

Contents of the invention

The object of the present invention is to provide an avalanche photodiode and a photomultiplier tube detector, which are used to improve the structure of the avalanche photodiode and can significantly improve the detection efficiency of the photomultiplier tube detector.

In order to achieve the above object, the present invention provides the following technical solutions:

An avalanche photodiode, comprising a substrate and an incident light anti-reflection layer;

The top surface of the substrate is a light incident surface; the incident light anti-reflection layer is disposed on the top surface of the substrate;

The substrate includes a plurality of doped regions; the doped regions are formed by doping impurity ions into the substrate; the doped regions include P-type heavily doped regions at the light incident end, N-type heavily doped A heterogeneous region, a P-type heavily doped region, a P-type doped region, and a P-type low-doped region; the P-type heavily doped region at the light incident end is located at the top of the substrate; the N-type heavily doped region and the P-type heavily doped region are located at the bottom of the substrate, the P-type heavily doped region is located on both sides of the N-type heavily doped region, and each of the P-type heavily doped regions There is a gap between the N-type heavily doped region; the P-type doped region is located above the N-type heavily doped region, and the bottom surface of the P-type doped region is in contact with the N-type heavily doped region. The top surfaces of the doped regions are attached together; except for the P-type heavily doped region at the light incident end, the N-type heavily doped region, the P-type heavily doped region and the region where the P-type doped region is located In addition, other regions of the substrate are all P-type low-doped regions;

The P-type heavily doped region is electrically connected to the anode terminal, and the N-type heavily doped region is electrically connected to the cathode terminal.

Compared with the prior art, the avalanche photodiode provided by the present invention designs the ion concentration and ion type doped into the substrate to form various types of doped regions on the substrate, and reasonably designs each The positional relationship between the doped regions can make the excitation avalanche multiplication effect of photo-generated carriers distributed on the entire substrate, greatly improving the range of photo-generated carriers triggering avalanche probability, thereby significantly improving the photoelectricity of using the avalanche photodiode. The detection efficiency of multiplier tube detectors.

The present invention also provides a photomultiplier tube detector, comprising a plurality of avalanche photodiode units; the plurality of avalanche photodiode units are connected in parallel;

Each of the avalanche photodiode units includes the aforementioned avalanche photodiode and a quenching resistor, and the avalanche photodiode and the quenching resistor are connected in series.

Compared with the prior art, the photomultiplier tube detector provided by the present invention includes an avalanche photodiode, so its beneficial effect is the same as that of the avalanche photodiode described in the above technical solution, and will not be repeated here.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute improper limitations to the present invention. In the attached picture:

FIG. 1 is a schematic structural diagram of an avalanche photodiode under a first implementation mode provided in an example of the present invention.

Fig. 2 is a schematic diagram of distribution of avalanche probability and electric field triggered by photogenerated carriers on a substrate provided in an embodiment of the present invention.

FIG. 3 is a schematic structural diagram of an avalanche photodiode in the prior art provided in an embodiment of the present invention.

FIG. 4 is a schematic structural diagram of an avalanche photodiode in a second implementation manner provided in an embodiment of the present invention.

FIG. 5 is a schematic diagram of another structure of an avalanche photodiode in the second implementation manner provided in the examples of the present invention.

FIG. 6 is a schematic structural diagram of an avalanche photodiode in a third implementation manner provided in an embodiment of the present invention.

FIG. 7 is a schematic diagram of another structure of an avalanche photodiode in the third implementation manner provided in the examples of the present invention.

Fig. 8 is a schematic diagram of the topological structure of the photomultiplier tube detector provided in the embodiment of the present invention.

Reference signs:

101-wafer substrate N+ area; 102-epitaxy layer N- area; 103-light incident end P+ area; 104-protection ring P- area; 105-incident light anti-reflection layer; Extinction resistance part; 108-cathode terminal.

1-substrate; 11-light incident end P-type heavily doped region; 12-N-type heavily doped region; 13-P-type heavily doped region; 14-P-type doped region; 15-P-type low-doped region 2-incident light anti-reflection layer; 3-substrate; 4-anode terminal; 5-cathode terminal; 6-isolation structure.

201 - avalanche photodiode; 202 - quenching resistor.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

It should be noted that when an element is referred to as being “fixed” or “disposed on” another element, it may be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, a feature defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined. "Several" means one or more than one, unless otherwise clearly and specifically defined.

In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right" etc. are based on those shown in the accompanying drawings. Orientation or positional relationship is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connection, or integral connection; it may be mechanical connection or electrical connection; it may be direct connection or indirect connection through an intermediary, and it may be the internal communication of two elements or the interaction relationship between two elements. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

Example 1:

Please refer to FIG. 1 , which shows a schematic longitudinal section of an avalanche photodiode 201 . This embodiment is used to provide an avalanche photodiode 201 , which includes a substrate 1 and an incident light anti-reflection layer 2 . The top surface of the substrate 1 is the light incident surface, and the incident light anti-reflection layer 2 is disposed on the top surface of the substrate 1 . The incident light anti-reflection layer 2 is specifically designed according to the wavelength corresponding to the detected photons, and the material used is an anti-reflection film material such as silicon dioxide, silicon nitride or indium tin oxide.

The substrate 1 includes a plurality of doping regions, which are formed by doping the substrate 1 with impurity ions, and the method used for doping the impurity ions may be ion implantation or diffusion. The doped region includes a P-type heavily doped region 11 , an N-type heavily doped region 12 , a P-type heavily doped region 13 , a P-type doped region 14 and a P-type low-doped region 15 at the light incident end. The P-type heavily doped region 13 is formed by doping the substrate 1 with an acceptor impurity with an ion concentration greater than a first preset concentration. The acceptor impurity refers to an element located in Group III of the periodic table, such as Boron or indium have only three electrons in their valence bands, and the first preset concentration is generally 1E18/cm ³ . The P-type doped region 14 is formed by doping the substrate 1 with an acceptor impurity whose ion concentration is less than or equal to the first preset concentration but greater than or equal to the second preset concentration. The second preset concentration is generally 1E14/cm ³ . The P-type low-doped region 15 is formed by doping the substrate 1 with an acceptor impurity whose ion concentration is lower than a second preset concentration. The N-type heavily doped region 12 is formed by doping the substrate 1 with a donor impurity whose ion concentration is greater than a first predetermined concentration, and the donor impurity can be pentavalent elements such as arsenic, phosphorus, and antimony. Furthermore, by doping impurity ions of different types and concentrations on the substrate 1 , multiple doped regions of different types are formed on the substrate 1 .

The P-type heavily doped region 11 at the light incident end is located on the top of the substrate 1 . The N-type heavily doped region 12 and the P-type heavily doped region 13 are located at the bottom of the substrate 1, the P-type heavily doped region 13 is located on both sides of the N-type heavily doped region 12, and each P-type heavily doped There is a gap between the region 13 and the N-type heavily doped region 12 . The P-type doped region 14 is located above the N-type heavily doped region 12 , and the bottom surface of the P-type doped region 14 is in contact with the top surface of the N-type heavily doped region 12 . Except for the regions where the P-type heavily doped region 11, the N-type heavily doped region 12, the P-type heavily doped region 13 and the P-type doped region 14 are located at the light incident end, other regions of the substrate 1 are P-type low The doping regions 15, and then rationally arrange the doping positions of each doping region. The P-type heavily doped region 13 is electrically connected to the anode terminal 4 , and the N-type heavily doped region 12 is electrically connected to the cathode terminal 5 .

During specific implementation: the anode terminal 4 is connected to the negative pole of the power supply, and the cathode terminal 5 is connected to the positive pole of the power supply to apply a reverse bias voltage to the avalanche photodiode 201 to make the avalanche photodiode 201 work in a breakdown state. Photons enter the substrate 1 through the top of the substrate 1, and excite the valence electrons of the semiconductor into free electrons. The free electrons generated are accelerated on the substrate 1, and a large number of secondary electrons are released. For the multiplication of hole carriers, the hole carriers are collected through the P-type heavily doped region 13, and the electron carriers are collected through the N-type heavily doped region 12, so as to improve the sensitivity of photoelectric conversion.

In this embodiment, after designing the type of doped regions on the substrate 1 and the positional relationship between each doped region, the probability of photogenerated carriers in the substrate 1 triggering an avalanche is shown in Figure 2(a). In 2(a), P is the probability of avalanche triggering, the dashed line Pe is the probability of avalanche triggering by electron carriers, the dashed line Ph is the probability of avalanche triggering by hole carriers, and the solid line is the triggering of electron carriers and hole carriers The relationship between the sum of avalanche probabilities and each doped region on the substrate 1 is shown in the corresponding relationship between FIG. 2(a) and FIG. 2(c). In FIG. 2(b), E is the electric field, and the relationship between the electric field distribution on the substrate 1 and each doped region on the substrate 1 is shown in the corresponding relationship between FIG. 2(b) and FIG. 2(c). Referring to FIG. 2, it can be seen that the excitation avalanche multiplication effect of photogenerated carriers is distributed on the entire substrate 1, and then the avalanche photodiode 201 structure provided by this embodiment can significantly improve the avalanche trigger range of photogenerated carriers, thereby significantly The detection efficiency of the photomultiplier tube detector using the avalanche photodiode 201 is improved.

As a possible implementation, the resistivity of the P-type low doped region 15 is between 0.1-100Ω.cm, the thickness is between 0.5-10um, and the junction depth of the N-type heavily doped region 12 is between 0.3-1um. Between, the concentration of the P-type doped region 14 is 1E14/cm ³ -1E17/cm ³ . When carrying out ion doping to substrate 1 to obtain N-type heavily doped region 12 and P-type doped region 14, try to make the ion concentration of N-type heavily doped region 12 on the same cross section the same, P-type doped The region 14 has the same ion concentration on the same cross section, so that a uniform electric field is generated on the contact surface of the N-type heavily doped region 12 and the P-type doped region 14, which is beneficial to improve the working efficiency of the avalanche photodiode 201 .

Please refer to Fig. 3, in the existing SiPM that is used for radiation detection or weak light detection, the basic structure of its single avalanche photodiode is as shown in Fig. 3, comprises wafer substrate N+ area (101), epitaxial layer N- area (102 ), the light incident end P+ area (103), the guard ring P- area (104), the incident light anti-reflection layer (105), the anode lead end (106), the quenching resistance part (107) and the cathode lead end (108) . However, the quenching resistor part (107) and the anode lead-out end (106) will block the light incident surface of the avalanche photodiode. In view of this blocking problem, the filling factor of the light entrance will be reduced, thereby affecting the detection efficiency. Based on this, the avalanche photodiode 201 provided in this embodiment also includes a substrate 3, which is a glass support substrate or a flexible substrate. The thickness of the substrate 3 can be adjusted according to processing conditions and application requirements, and can be between 20-500um . The substrate 3 is located below the substrate 1 , and the top surface of the substrate 3 is attached to the bottom surface of the substrate 1 , that is, the substrate 3 is drawn from the non-detection photon side of the avalanche photodiode 201 . The substrate 3 is provided with a plurality of grooves along the height direction, the grooves are used to place the anode lead-out 4 and the cathode lead-out 5, both the anode lead-out 4 and the cathode lead-out 5 are drawn from the bottom of the substrate 1, that is, both are drawn from the bottom of the substrate 1. The side of the non-detection photon is led out, thereby avoiding the problem of blocking the photon detection surface, can improve the filling factor of the light entrance, and significantly improve the detection efficiency of the photomultiplier tube detector using the avalanche photodiode 201 .

First define the directions of length, width and height in detail. Define the arrangement direction of the N-type heavily doped region 12 and the P-type heavily doped region 13 as the width direction, that is, take Fig. 1 as an example, the lateral direction shown in Fig. 1 is the defined width direction, because the lining For the top and bottom of the bottom 1, the vertical direction shown in Figure 1 is the height direction, and the direction perpendicular to the paper surface not shown in Figure 1 is the length direction.

Referring to Fig. 1, the top surface of the substrate 1 in this embodiment can be a plane, and the top surfaces of the N-type heavily doped region 12, the P-type heavily doped region 13 and the P-type doped region 14 can be a plane or an arbitrary curved surface, Its longitudinal section can be in any shape, and what Fig. 1 shows is the situation that the top surface is a plane and the longitudinal section is a rectangle. The cross-sectional area of the P-type heavily doped region 11 at the light incident end is equal to the cross-sectional area of the substrate 1, and the lengths of the N-type heavily doped region 12, the P-type heavily doped region 13 and the P-type doped region 14 are all equal to The lengths of the substrates 1 are equal, so that the avalanche trigger range of the generated photo-generated carriers can be within the entire three-dimensional structure of the substrate 1, further improving the detection efficiency of the photomultiplier tube detector using the avalanche photodiode 201 .

As an optional implementation, the top surface of the substrate 1 is a concave-convex surface, which can increase the light receiving area of the avalanche photodiode 201 and further improve the detection efficiency of the photomultiplier tube detector using the avalanche photodiode 201 . The vertical cross-sectional shape of the N-type heavily doped region 12 , the P-type heavily doped region 13 and the P-type doped region 14 can be any shape. In addition, the substrate 1 is doped with impurity ions of a predetermined thickness from the top surface of the substrate 1 to form a P-type heavily doped region 11 at the light incident end, so that the P-type heavily doped region 11 at the light incident end is in contact with the top surface of the substrate 1. The same shape, and the lengths of N-type heavily doped region 12, P-type heavily doped region 13 and P-type doped region 14 are all equal to the length of substrate 1, which can trigger the avalanche of photo-generated carriers generated The range is inside the three-dimensional structure of the entire substrate 1 , which further improves the detection efficiency of the photomultiplier tube detector using the avalanche photodiode 201 .

In order to simplify the processing technology of the substrate 1, the top surface of the substrate 1 can only have a first raised portion, and the longitudinal cross-sectional shape of the first raised portion can be any shape, such as trapezoidal, semicircular or polygonal, etc. . Please refer to Fig. 4 and Fig. 5, which have provided the embodiment that the longitudinal section shape of the first raised portion is trapezoidal, arranging a first raised portion can also increase the light-receiving area of the avalanche photodiode 201, and further improve the application of the The detection efficiency of the photomultiplier tube detectors of the avalanche photodiodes 201 and the provision of a first protrusion to form a mesa structure on the top surface of the substrate 1 can suppress the charge crosstalk between the avalanche photodiodes 201 to a certain extent. In this embodiment, the high part of the formed mesa structure can be specifically designed as the main photon detection region, and the P-type heavily doped region 13 is set at the corresponding position of the low part.

When the top surface of the substrate 1 has a first raised portion, the top surfaces of the N-type heavily doped region 12 and the P-type doped region 14 can be designed to have the same shape as the first raised portion. Specifically, referring to FIG. 4 and FIG. 5, when the longitudinal cross-sectional shape of the first raised portion of the substrate 1 is trapezoidal, the longitudinal cross-sectional shape of the N-type heavily doped region 12 is set to be trapezoidal, and the P-type doped region 14 The cross-sectional shape of the region formed with the N-type heavily doped region 12 is also trapezoidal, but the size of the trapezoid can be different. The N-type heavily doped region 12 of a specific shape is grown by epitaxy and then etching. Through the design that the top surfaces of the N-type heavily doped region 12 and the P-type doped region 14 have the same shape as the first raised portion, the electric field distribution on the substrate 1 can be made more uniform, and the working state of the avalanche photodiode 201 can be improved. stability, and at the same time increase the collection speed of the generated photo-generated carriers, which can suppress the charge crosstalk between the avalanche photodiodes 201 to a certain extent.

In order to improve the stability of the working state of the avalanche photodiode 201 and suppress the charge crosstalk between the avalanche photodiodes 201, and at the same time simplify the manufacturing process of the avalanche photodiode 201, this embodiment also provides another implementation method, such as As shown in Fig. 6 and Fig. 7, the top surface of the substrate 3 has a second protruding part having the same shape as the first protruding part, and the N-type heavily doped The impurity region 12 and the P-type doped region 14 grow the P-type highly doped region 13 and the isolation structure 6 in the low part, thereby reducing the manufacturing complexity of the N-type heavily doped region 12 and the P-type doped region 14, avoiding Making the top surfaces of the N-type heavily doped region 12 and the P-type doped region 14 into the same shape as the top surface of the substrate 1 brings about the difficulty of the process, while improving the stability of the working state of the avalanche photodiode 201 and the effect of suppressing charge crosstalk between the avalanche photodiodes 201.

Since the avalanche photodiodes 201 included in the photomultiplier tube detector are arranged in close series, considering the charge crosstalk between each avalanche photodiode 201, the present embodiment can make the height of the P-type heavily doped region 13 higher than The height of the horizontal line where the top surface of the P-type doped region 14 is located, the longitudinal cross-sectional shape of the P-type heavily doped region 13 can be trapezoidal or columnar, by making the height of the P-type heavily doped region 13 higher than the P-type doped The height of the horizontal line where the top surface of the region 14 is located can effectively shield the charge crosstalk between the avalanche photodiodes 201, and can also improve the fill factor of the light entrance, thereby improving the detection of the photomultiplier tube detector using the avalanche photodiode 201. efficiency.

In order to effectively shield the charge crosstalk between the avalanche photodiode units, this embodiment also provides another specific implementation manner. The avalanche photodiode 201 also includes an isolation structure 6, which can be an isolation trench structure, whose material can be a passivation such as silicon oxide or silicon nitride, and whose longitudinal section can be trapezoidal or columnar. The isolation structure 6 is disposed on the P-type heavily doped region 13 , and the isolation structure 6 can be disposed on the top surface of the P-type heavily doped region 13 , or on the side away from the N-type heavily doped region 12 . As shown in FIG. 7 , the isolation structure 6 on the left is disposed inside the P-type heavily doped region 13 , and the isolation structure 6 on the right is disposed on the side of the P-type heavily doped region 13 away from the N-type heavily doped region 12 . The height of the horizontal line where the top surface of the isolation structure 6 is higher than the height of the horizontal line where the top surface of the P-type doped region 14 is located, or, when the top surface of the substrate 1 is a concave-convex surface, the top surface of the isolation structure 6 and the substrate The recessed part of the bottom 1 fits together, thereby effectively avoiding charge crosstalk between the avalanche photodiodes 201, and can also improve the fill factor of the light entrance, thereby improving the detection efficiency of the photomultiplier tube detector using the avalanche photodiode 201 .

Example 2:

An embodiment of the present invention also provides a photomultiplier tube detector. As shown in FIG. 8 , the detector includes a plurality of avalanche photodiode units, and the plurality of avalanche photodiode units are connected in parallel.

Each avalanche photodiode unit includes an avalanche photodiode 201 and a quenching resistor 202 as described in Embodiment 1, and the avalanche photodiode 201 and the quenching resistor 202 are connected in series.

Anode terminals 4 of all avalanche photodiodes are connected in parallel, and cathode terminals 5 of all avalanche photodiodes are connected in parallel.

The two adjacent avalanche photodiodes 201 are respectively denoted as the first avalanche photodiode and the second avalanche photodiode, and the P-type heavily doped region 13 of the avalanche photodiode is respectively denoted as the first P-type heavily doped region and the second P-type heavily doped region. The heavily doped region, the first P-type heavily doped region of the first avalanche photodiode and the second P-type heavily doped region of the second avalanche photodiode are the same P-type heavily doped region 13, and then two adjacent The avalanche photodiode 201 can share the P-type heavily doped region 13 , which can reduce the manufacturing process complexity of the avalanche photodiode 201 .

It should be noted that when two avalanche photodiodes 201 share the P-type heavily doped region 13, the isolation structure 6 cannot be arranged on one side of the P-type heavily doped region 13, but can be located on the side of the P-type heavily doped region 13. The top surface or the interior of the P-type heavily doped region 13 .

Compared with the prior art, the photomultiplier tube detector provided by the embodiment of the present invention adopts the avalanche photodiode 201 described in Embodiment 1, and by improving the structure of the avalanche photodiode 201, the filling of the light entrance can be improved. Factor, to avoid charge crosstalk between the avalanche photodiodes 201, increase the light detection surface area of the avalanche photodiodes 201, thereby improving the detection efficiency of the photomultiplier tube detector.

In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in an appropriate manner.

In the above description, technical details such as patterning and etching of each layer are not described in detail. However, those skilled in the art should understand that various technical means can be used to form layers, regions, etc. of desired shapes. In addition, in order to form the same structure, those skilled in the art can also design a method that is not exactly the same as the method described above. In addition, although the various embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be advantageously used in combination.

The embodiments of the present disclosure have been described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The scope of the present disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the present disclosure, and these substitutions and modifications should all fall within the scope of the present disclosure.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (6)

1. an avalanche photodiode, is characterized in that, comprises substrate and incident light anti-reflection layer; The top surface of the substrate is a light incident surface; the incident light anti-reflection layer is disposed on the top surface of the substrate; The substrate includes a plurality of doped regions; the doped regions are formed by doping impurity ions into the substrate; the doped regions include P-type heavily doped regions at the light incident end, N-type heavily doped A heterogeneous region, a P-type heavily doped region, a P-type doped region, and a P-type low-doped region; the P-type heavily doped region at the light incident end is located at the top of the substrate; the N-type heavily doped region and the P-type heavily doped region are located at the bottom of the substrate, the P-type heavily doped region is located on both sides of the N-type heavily doped region, and each of the P-type heavily doped regions There is a gap between the N-type heavily doped region; the P-type doped region is located above the N-type heavily doped region, and the bottom surface of the P-type doped region is in contact with the N-type heavily doped region. The top surfaces of the doped regions are attached together; except for the P-type heavily doped region at the light incident end, the N-type heavily doped region, the P-type heavily doped region and the region where the P-type doped region is located In addition, other regions of the substrate are all P-type low-doped regions; The P-type heavily doped region is electrically connected to the anode terminal, and the N-type heavily doped region is electrically connected to the cathode terminal; The avalanche photodiode also includes a substrate; the substrate is located below the substrate, and the top surface of the substrate is attached to the bottom surface of the substrate; the top surface of the substrate is a concave-convex surface with a a first raised portion; the top surface of the substrate has a second raised portion having the same shape as the first raised portion; the N-type heavily doped region is located on the second raised portion; The height of the P-type heavily doped region is higher than the height of the horizontal line where the top surface of the P-type doped region is located; or, the avalanche photodiode further includes an isolation structure; the isolation structure is arranged on the P-type On the heavily doped region: the height of the horizontal line where the top surface of the isolation structure is located is higher than the height of the horizontal line where the top surface of the P-type doped region is located. 2. The avalanche photodiode according to claim 1, wherein the substrate is provided with a plurality of grooves along the height direction, and the grooves are used to place the anode lead-out end and the cathode terminal. 3 . The avalanche photodiode according to claim 1 , wherein both the anode lead-out terminal and the cathode lead-out end are drawn out from the bottom of the substrate. 4 . 4. The avalanche photodiode according to claim 2, characterized in that, the substrate is doped with impurity ions of a predetermined thickness from the top surface of the substrate to form a P-type heavy doping at the light incident end. Miscellaneous area. 5 . The avalanche photodiode according to claim 1 , wherein the top surfaces of the N-type heavily doped region and the P-type doped region have the same shape as the first protrusion . 6. A photomultiplier tube detector, characterized in that, comprises a plurality of avalanche photodiode units; a plurality of said avalanche photodiode units are connected in parallel; Each of the avalanche photodiode units includes the avalanche photodiode and the quenching resistor according to any one of claims 1-5, and the avalanche photodiode and the quenching resistor are connected in series.

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