Single photon avalanche diode, photoelectric detector and detection device

Abstract

The embodiment of the invention discloses a single photon avalanche diode, a photoelectric detector and a detection device, relates to the technical field of image sensors, and is used for solving the problem that the dynamic range of an SPAD photoelectric detector is insufficient in a strong light environment. The single photon avalanche diode comprises a first electrode, a second electrode and a wafer. The wafer comprises a first surface and a second surface; the wafer further comprises a main body part, a first doping part, a second doping part and a third doping part, wherein the first doping part and the second doping part are stacked in the first direction; the main body part is coupled with the first electrode; the first doping part and the second doping part form a PN junction connected with the main body part; the first doping part is coupled with the second electrode; the third doping part is arranged on one side, far away from the first doping part, of the second doping part; the doping types of the second doping part and the third doping part are opposite; some embodiments of the present disclosure provide a single photon avalanche diode for photoelectric detection.

Description

Technical Field

[0001] The present disclosure relates to the technical field of image sensors, and particularly to a single-photon avalanche diode, a photodetector, and a detection device. Background Art

[0002] A single-photon avalanche diode (SPAD, Single Photon Avalanche Diode) is a photodetection device. Since it operates above the reverse breakdown voltage and has a large avalanche gain, for example, it can reach 10 5 or more, and has a good signal-to-noise ratio. Therefore, the single-photon avalanche diode not only has single-photon detection sensitivity, but also has good time response and time resolution ability at the picosecond level.

[0003] However, when the SPAD photodetector is applied to a strong light environment, there is a problem of insufficient dynamic range, manifested as poor linearity of the output response, which will affect the final detection effect and / or imaging effect. Summary of the Invention

[0004] Some embodiments of the present disclosure provide a single-photon avalanche diode, a photodetector, and a detection device, which are used to solve the problem of insufficient dynamic range of the SPAD photodetector in a strong light environment.

[0005] In a first aspect, a single-photon avalanche diode is provided. The single-photon avalanche diode includes a first electrode, a second electrode, and a wafer. The first electrode and the second electrode are arranged at intervals. The wafer includes a first surface and a second surface opposite to each other in a first direction, and the first direction is the thickness direction of the wafer. The wafer further includes: a main body portion, a first doping portion and a second doping portion stacked in the first direction, and a third doping portion. The main body portion is coupled to the first electrode. The first doping portion is farther from the second surface than the second doping portion; the first doping portion and the second doping portion form a PN junction connected to the main body portion, and the doping types of the first doping portion and the main body portion are opposite; the first doping portion is coupled to the second electrode. The third doping portion is provided on a side of the second doping portion away from the first doping portion; the doping types of the second doping portion and the third doping portion are opposite.

[0006] Understandably, when a single-photon avalanche diode operates, photo-generated carriers will undergo impact ionization in the avalanche region, generating an avalanche multiplication effect, forming a depletion region of a certain range on the wafer, and the depletion region will expand in the direction away from the first doping portion of the second doping portion. When the single-photon avalanche diode further includes a third doping portion and the doping types of the second doping portion and the third doping portion are opposite, it is equivalent to forming a low-barrier region on the side of the second doping portion away from the first doping portion. In this way, when the absolute value of the overbias voltage is relatively low, the low-barrier region formed by the third doping portion will block the expansion of the depletion region to the side of the third doping portion away from the second doping portion, resulting in a relatively low photon detection efficiency of the single-photon avalanche diode; when the absolute value of the overbias voltage is relatively high, the barrier of the low-barrier region formed by the third doping portion will be broken down, enabling the depletion region to expand to the side of the third doping portion away from the second doping portion to achieve a relatively high photon detection efficiency.

[0007] Therefore, by providing that the single-photon avalanche diode further includes a third doping portion and the doping types of the second doping portion and the third doping portion are opposite, the difference in photon detection efficiency between the case of a relatively low absolute value of the overbias voltage and the case of a relatively high absolute value of the overbias voltage can be increased. In this way, the photon detection efficiency of the single-photon avalanche diode can be adjusted by adjusting the overbias voltage, and a large change in photon detection efficiency can be achieved within a relatively small overbias voltage adjustment range. For example, a photon detection efficiency adjustment range of more than 20 times can be achieved. Thus, the count rate of the single-photon avalanche diode can remain unsaturated in a strong light environment, and further the output response is linear, which can solve the problem of insufficient dynamic range of the SPAD photodetector in a strong light environment.

[0008] Optionally, the second doping portion is in contact with the third doping portion.

[0009] Optionally, the second doping portion and the third doping portion are connected through a partial main body portion.

[0010] Optionally, the size of the first doping portion in the second direction is greater than the size of the second doping portion in the second direction, and the second direction is perpendicular to the first direction.

[0011] Optionally, the size of the second doping portion in the second direction is greater than the size of the third doping portion in the second direction, and the second direction is perpendicular to the first direction.

[0012] Optionally, the surface of the first doping portion away from the second doping portion forms a part of the first surface; the first doping portion is in contact with the second electrode.

[0013] Optionally, the wafer further includes a fourth doped portion. The fourth doped portion is in contact with the surface of the first doped portion away from the second doped portion and is wrapped by the first doped portion. The doping type of the fourth doped portion is the same as that of the first doped portion, and the doping concentration of the fourth doped portion is greater than that of the first doped portion. The surface of the fourth doped portion away from the second doped portion forms a part of the first surface; the fourth doped portion is in contact with the second electrode.

[0014] Optionally, the wafer further includes a fifth doped portion. The fifth doped portion is disposed on one side of the main body portion and is connected to the main body portion. The surface of the fifth doped portion away from the second surface forms a part of the first surface. The fifth doped portion is spaced apart from the first doped portion. The doping type of the fifth doped portion is the same as that of the main body portion, and the doping concentration of the fifth doped portion is greater than that of the main body portion; the fifth doped portion is in contact with the first electrode.

[0015] Optionally, the wafer further includes a sixth doped portion. The sixth doped portion is disposed between the fifth doped portion and the main body portion and wraps the fifth doped portion. The sixth doped portion is spaced apart from the first doped portion. The doping types of the fifth doped portion and the sixth doped portion are the same, the doping concentration of the sixth doped portion is greater than that of the main body portion, and less than that of the fifth doped portion.

[0016] Optionally, the fifth doped portion and the sixth doped portion are in a ring structure, and the first doped portion, the second doped portion, the third doped portion, and the second electrode are disposed inside the fifth doped portion and inside the sixth doped portion. The wafer further includes: an isolation portion surrounding the sixth doped portion.

[0017] Optionally, the isolation portion includes a first outer boundary and a second outer boundary opposite to each other in a second direction perpendicular to the first direction, and the first outer boundary and the second outer boundary have a first distance in the second direction. The boundary where the first doped portion and the sixth doped portion are close to each other has a second distance in the second direction. The ratio range of the second distance to the first distance is 0.02 to 0.5.

[0018] Optionally, the shape of the orthographic projection of any one of the first doped portion, the second doped portion, the third doped portion, and the fourth doped portion on the second surface includes a circle, a square, or a regular octagon. The shape of the orthographic projection of the fifth doped portion on the second surface includes a ring, the inner boundary of the ring is in the shape of a circle, a square, or a regular octagon, and the outer boundary of the ring is in the shape of a circle, a square, or a regular octagon.

[0019] Optionally, the doping type of the third doped portion is N-type.

[0020] In a second aspect, a photodetector is provided. The photodetector includes a single-photon avalanche diode and a logic circuit provided by the above technical solution. The logic circuit is coupled to the first electrode and the second electrode respectively.

[0021] The beneficial effects achievable by the photodetectors provided by some embodiments of the present disclosure are the same as those achievable by a single-photon avalanche diode provided by the above technical solution, and will not be elaborated here.

[0022] Optionally, the photon detection surface of the single-photon avalanche diode is the second surface. The logic circuit is connected to the first surface of the single-photon avalanche diode.

[0023] In a third aspect, a detection device is provided. The detection device includes the photodetector provided by the above technical solution.

[0024] The beneficial effects achievable by the detection device provided by some embodiments of the present disclosure are the same as those achievable by a photodetector provided by the above technical solution, and will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are used to provide a further understanding of the embodiments of the present disclosure, and constitute a part of the embodiments of the present disclosure. The schematic embodiments of the present disclosure and the descriptions thereof are used to explain the present disclosure, and do not constitute an improper limitation of the present disclosure. In the drawings: Figure 1 is a cross-sectional structure diagram of a single-photon avalanche diode provided by some embodiments of the present disclosure; Figure 2 is a position reference diagram of the orthographic projection of some structures of a single-photon avalanche diode provided by some embodiments of the present disclosure on the second surface; Figure 3 is a simulation diagram of the device potential distribution of a single-photon avalanche diode provided by some embodiments of the present disclosure; Figure 4 is a simulation diagram of the avalanche breakdown probability distribution of a single-photon avalanche diode provided by some embodiments of the present disclosure; Figure 5 is a curve graph showing the variation of the potential at each point on the center line of a single-photon avalanche diode provided by some embodiments of the present disclosure with depth; Figure 6 is Figure 5 a partial enlarged view of some curves in Figure 7 is a cross-sectional structure diagram of another single-photon avalanche diode provided by some embodiments of the present disclosure; Figure 8 is a cross-sectional structure diagram of another single-photon avalanche diode provided by some embodiments of the present disclosure; Figure 9 is a position reference diagram of the orthographic projection of some structures of another single-photon avalanche diode provided by some embodiments of the present disclosure on the second surface; Figure 10 A position reference diagram of the orthographic projection on the second surface of some structures of another single-photon avalanche diode provided by some embodiments of the present disclosure; Figure 11 An arrangement diagram of a single-photon avalanche diode of a photodetector provided by some embodiments of the present disclosure; Figure 12 An arrangement diagram of a single-photon avalanche diode of another photodetector provided by some embodiments of the present disclosure; Figure 13 An arrangement diagram of a single-photon avalanche diode of another photodetector provided by some embodiments of the present disclosure; Figure 14 A structural diagram of a photodetector provided by some embodiments of the present disclosure; Figure 15 A structural diagram of a detection device provided by some embodiments of the present disclosure. Detailed implementation manners

[0026] Next, the technical solutions in some embodiments of the present disclosure will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present disclosure.

[0027] Unless otherwise required by the context, throughout the specification and claims, the term "comprising" is interpreted in an open, inclusive sense, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "examples" or "some examples", etc., are intended to indicate that specific features, structures, materials or characteristics related to the embodiment or example are included in at least one embodiment or example of the present disclosure. The schematic representations of the above terms are not necessarily referring to the same embodiment or example. In addition, the described specific features, structures, materials or characteristics can be included in any one or more embodiments or examples in any appropriate manner.

[0028] In the description of the embodiments of the present disclosure, unless otherwise specified, the meaning of "a plurality" is two or more.

[0029] As used herein, "parallel", "perpendicular", and "equal" include the stated cases and cases similar to the stated cases, where the range of the similar cases is within an acceptable deviation range, and the acceptable deviation range is determined by those of ordinary skill in the art considering the measurements under discussion and the errors associated with the measurements of specific quantities (i.e., the limitations of the measurement system). For example, "parallel" includes absolute parallelism and approximate parallelism, where the acceptable deviation range for approximate parallelism can be, for example, a deviation within 5°; "perpendicular" includes absolute perpendicularity and approximate perpendicularity, where the acceptable deviation range for approximate perpendicularity can also be, for example, a deviation within 5°. "Equal" includes absolute equality and approximate equality, where the acceptable deviation range for approximate equality can be, for example, that the difference between the two equal values is less than or equal to 5% of either one of them.

[0030] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, unless otherwise specified, "a plurality of" means two or more.

[0031] As described in the background art, a single-photon avalanche diode (SPAD) is a solid-state photodetector avalanche diode with single-photon detection ability and has attracted much attention in recent years. The working principle of SPAD for detecting photons is as follows: A bias voltage greater than the breakdown voltage is applied to the SPAD. When a photon is incident, a valence-band electron absorbs the photon and jumps to the conduction band, generating a photo-generated electron-hole pair. The photo-generated electron-hole pair is accelerated under the action of the applied electric field and obtains sufficient energy to collide with the lattice to generate new electron-hole pairs, and this process is called impact ionization. The new electron-hole pairs are accelerated under the action of the applied electric field and collide with the lattice to generate new electron-hole pairs. This process repeats, causing the number of carriers in the SPAD to increase rapidly and the current to increase sharply, forming a large avalanche current, and this phenomenon is called the avalanche multiplication effect.

[0032] According to the above principle of SPAD detecting single photons, since the SPAD operates above the reverse breakdown voltage, compared with an avalanche photodiode (APD), the avalanche gain of the SPAD is larger and can reach 10 5 Above, the signal-to-noise ratio is good. Therefore, it not only has single-photon detection sensitivity but also has good time response and time resolution capabilities, and can realize functions such as ranging. Currently, it has very important application prospects in fields such as lidar, 3D imaging, and medical imaging.

[0033] Figure 1A cross-sectional structure diagram of a single-photon avalanche diode provided for some embodiments of the present disclosure; Figure 2 A position reference diagram of the orthographic projection of some structures of a single-photon avalanche diode provided for some embodiments of the present disclosure on a second surface.

[0034] In some embodiments, as Figure 1 and Figure 2 shown, the single-photon avalanche diode 100 includes a first electrode 110 and a second electrode 120, and the first electrode 110 and the second electrode 120 are spaced apart.

[0035] Exemplarily, the first electrode 110 is a metal electrode, such as a copper electrode, an aluminum electrode or a silver electrode. The process for forming the first electrode 110 is, for example, an evaporation process, a sputtering process or a deposition process.

[0036] Exemplarily, the second electrode 120 is a metal electrode, such as a copper electrode, an aluminum electrode or a silver electrode. The process for forming the second electrode 120 is, for example, an evaporation process, a sputtering process or a deposition process.

[0037] The above-mentioned first electrode 110 and second electrode 120 being spaced apart means that there is a gap between the first electrode 110 and the second electrode 120 and they do not directly contact. Exemplarily, the gap provided between the first electrode 110 and the second electrode 120 can be filled with a material. For example, as Figure 14 shown, the gap provided between the first electrode 110 and the second electrode 120 can be filled with the material of the first dielectric layer 214 described in detail below.

[0038] Through the above arrangement, by using the first electrode 110 and the second electrode 120, a low voltage and a high voltage can be respectively connected to the single-photon avalanche diode 100, and the voltage difference between the low voltage and the high voltage is the bias voltage applied to the single-photon avalanche diode 100.

[0039] In some embodiments, as Figure 1 and Figure 2 shown, the single-photon avalanche diode 100 further includes a wafer 130. The wafer 130 includes a first surface 130a and a second surface 130b that are opposite in a first direction X, and the first direction X is the thickness direction of the wafer 130.

[0040] The wafer 130 further includes a main body portion 131, a first doping portion 132 and a second doping portion 133. The main body portion 131 is coupled to the first electrode 110.

[0041] The first doping portion 132 and the second doping portion 133 are stacked along the first direction X. The first doping portion 132 is farther from the second surface 130b than the second doping portion 133. The first doping portion 132 and the second doping portion 133 form a PN (Positive Negative) junction connected to the main body portion 131, and the doping types of the first doping portion 132 and the main body portion 131 are opposite. The first doping portion 132 is coupled to the second electrode 120.

[0042] In some examples, the first electrode 110 is used to apply a low voltage to the single-photon avalanche diode 100; the second electrode 120 is used to apply a high voltage to the single-photon avalanche diode 100. At this time, the bias voltage is a negative voltage, and the absolute value of the bias voltage is the sum of the absolute value of the breakdown voltage and the absolute value of the overbias voltage.

[0043] Exemplarily, the wafer 130 can be a silicon substrate, a germanium substrate, a germanium-silicon substrate, a silicon-on-insulator substrate, an indium gallium arsenide substrate, a gallium arsenide substrate, a silicon carbide substrate, or other suitable materials, etc.

[0044] Exemplarily, elements such as boron, indium, and gallium can be doped on the wafer 130 or the epitaxial layer to form a uniform P-type structure; or, elements such as phosphorus, arsenic, and antimony can be doped on the wafer 130 or the epitaxial layer to form a uniform N-type structure, so that the doped part of the wafer 130 forms the first doping portion 132 or the second doping portion 133, and the PN junction formed by the first doping portion 132 and the second doping portion 133 is connected to the main body portion 131. The above doping process is, for example, an ion implantation process or a diffusion process.

[0045] In some examples, part or all of the portion of the first doping portion 132 away from the surface 132a of the second doping portion 133 forms a part of the first surface 130a. At this time, at least part of the first doping portion 132 is exposed on the first surface 130a.

[0046] Exemplarily, the areas of the first surface 130a and the second surface 130b of the wafer 130 can be the same or different. Moreover, the first surface 130a and the second surface 130b can be a plane, a curved surface, or a stepped surface. For example, the first surface 130a can be a stepped surface. At this time, the surface 132a of the first doping portion 132 away from the second doping portion 133 can be higher than the main body portion 131 or lower than the main body portion 131.

[0047] Exemplarily, the first doping portion 132 can be a single-layer structure, or the first doping portion 132 can be a multi-layer structure including multiple first sub-doping layers with the same doping type, and the multiple first sub-doping layers are stacked.

[0048] Exemplarily, the second doping portion 133 may be a single-layer structure, or the second doping portion 133 may be a multi-layer structure including a plurality of second sub-doping layers of the same doping type, and the plurality of second sub-doping layers are stacked.

[0049] When a PN junction is formed between the first doping portion 132 and the second doping portion 133, the doping type of the first doping portion 132 is opposite to that of the second doping portion 133, and the first doping portion 132 and the second doping portion 133 are in contact; when the PN junction formed by the first doping portion 132 and the second doping portion 133 is connected to the main body portion 131, the first doping portion 132 and the second doping portion 133 may form a depletion region within the wafer 130. Here, the doping type of the first doping portion 132 being opposite to that of the second doping portion 133 means that one of the doping elements in the first doping portion 132 and the doping elements in the second doping portion 133 is a P-type doping element and the other is an N-type doping element.

[0050] Exemplarily, as Figure 1 and Figure 2 shown, the PN junction formed by the first doping portion 132 and the second doping portion 133 is located in the central region of the wafer 130.

[0051] Based on the above structure, by using the first electrode 110 and the second electrode 120, a reverse bias voltage with an absolute value higher than the reverse breakdown voltage can be applied to the single-photon avalanche diode 100, and an avalanche region with a relatively high electric field strength can be formed around the first doping portion 132 and the second doping portion 133. In this way, when a photon enters the single-photon avalanche diode 100, it will be absorbed by the main body portion 131 of the wafer 130 to generate photo-generated carriers. These photo-generated carriers either drift to the avalanche region under the action of the electric field, or first diffuse into the depletion region under the action of the concentration difference and then drift to the avalanche region under the action of the electric field, and collision ionization occurs in the avalanche region to form an avalanche multiplication effect, generating a large number of carriers. Among them, electrons flow to the second electrode 120, and holes flow to the first electrode 110, forming a large avalanche current, thereby realizing the function of photoelectric detection.

[0052] Here, the present disclosure embodiment does not limit the incident side of the photon. For example, the photon may enter from one side of the first surface 130a (i.e., front incident); for another example, as Figure 14 shown, the photon may enter from one side of the second surface 130b (i.e., back incident).

[0053] In the related art, since the SPAD belongs to a photon-counting detection device, its unique avalanche-quenching-recovery mechanism limits the maximum counting rate. When applied to a strong light environment, the incident light is strong, which easily causes the counting rate of the SPAD pixels to reach saturation, making its output response non-linear, thereby affecting the final detection effect and / or imaging effect of the SPAD photodetector (for example, the SPAD image sensor).

[0054] In some implementation manners, an ambient light adjustment device applicable to an image sensor is provided. The ambient light adjustment device includes a controller and an adjustment device. Among them, the controller is configured to: when the detection intensity value of the image sensor is greater than or equal to a preset threshold, control the adjustment device to weaken the intensity of the light received by the image sensor and / or reduce the bias voltage at which the image sensor operates, so as to reduce the intensity value of the light received by the image sensor, so that the intensity value of the light received by the image sensor meets the requirements of the optimal working range interval for the ambient light intensity. In this implementation manner, adjusting the bias voltage at which the image sensor operates is actually to adjust the response ability of the image sensor. For the SPAD image sensor, it can be understood as adjusting the photon detection efficiency of the SPAD pixels, thereby avoiding the saturation of the output counting rate.

[0055] However, when using the above control and adjustment device to weaken the intensity of the light received by the image sensor so that the intensity value of the light received by the image sensor meets the requirements of the optimal working range interval for the ambient light intensity, there are problems of slow response, high cost, and large volume. On the other hand, when using the implementation manner of reducing the bias voltage at which the image sensor operates, limited by the threshold voltage and breakdown voltage withstand ability of the MOS, the adjustable range of the over-bias voltage of the SPAD image sensor is limited, and the adjustable range of the photon detection efficiency that can be achieved is also limited. For example, for the logic circuit of the SPAD sensor designed based on the mature CMOS process, the generally provided adjustable range of the over-bias voltage is relatively narrow (for example, -3.3V to -1.2V), and within the narrow adjustable range of the over-bias voltage, the adjustable range of the photon detection efficiency that can be achieved is limited.

[0056] The inventors of the present disclosure found that the photon detection efficiency of the single-photon avalanche diode 100 is positively correlated with the photon absorption amount of the single-photon avalanche diode 100, and is also positively correlated with the integral value of the avalanche breakdown probability in the depletion region. Among them, the photon absorption amount of the single-photon avalanche diode 100 is positively correlated with the thickness of the single-photon avalanche diode 100; the integral value of the avalanche breakdown probability in the depletion region is positively correlated with the area of the depletion region. Therefore, the photon detection efficiency of the single-photon avalanche diode 100 can be adjusted by adjusting the photon absorption amount of the single-photon avalanche diode 100 and / or the area of the depletion region.

[0057] However, limited by factors such as the device size of the photodetector, the adjustable range of the thickness of the single-photon avalanche diode 100 is relatively small, resulting in a relatively small adjustable range of the photon absorption amount of the single-photon avalanche diode 100. Therefore, adjusting the photon detection efficiency of the single-photon avalanche diode 100 by adjusting the area of the depletion region is a method with relatively high feasibility.

[0058] Based on this, some embodiments of the present disclosure provide a single-photon avalanche diode 100. As Figure 1 and Figure 2 shown, the single-photon avalanche diode 100 further includes a third doping portion 134. The third doping portion 134 is disposed on a side of the second doping portion 133 away from the first doping portion 132; the doping types of the second doping portion 133 and the third doping portion 134 are opposite.

[0059] Exemplarily, the third doping portion 134 may be a single-layer structure, or the third doping portion 134 may be a multi-layer structure including a plurality of third sub-doping layers with the same doping type, and the plurality of third sub-doping layers are stacked.

[0060] It should be understood that in the case where the doping types of the second doping portion 133 and the third doping portion 134 are opposite, the doping type of the third doping portion 134 and the main body portion 131 are opposite.

[0061] Exemplarily, as Figure 1 shown, the third doping portion 134 includes a third surface and a fourth surface opposite to each other in the first direction X, and further includes at least one side surface connecting the third surface and the fourth surface. The third surface is closer to the second doping portion 133 than the fourth surface. The fourth surface and each side surface of the third doping portion 134 are in contact with the main body portion 131.

[0062] It can be understood that when the single-photon avalanche diode 100 operates, photo-generated carriers will undergo impact ionization in the avalanche region, generating an avalanche multiplication effect, forming a depletion region with a certain range on the wafer 130, and the depletion region will expand in the direction away from the first doping portion 132 of the second doping portion 133 (for example, along Figure 1 the downward direction in

[0063] When the single-photon avalanche diode 100 further includes a third doping portion 134 and the doping types of the second doping portion 133 and the third doping portion 134 are opposite, it is equivalent to forming a low-barrier region on the side of the second doping portion 133 far from the first doping portion 132. For example, a low-barrier region is formed between the second doping portion 133 and the main body portion 131. In this way, when the absolute value of the overbias voltage is relatively low, the low-barrier region formed by the third doping portion 134 will block the depletion region from expanding to the side of the third doping portion 134 far from the second doping portion 133, resulting in a relatively low photon detection efficiency of the single-photon avalanche diode 100; when the absolute value of the overbias voltage is relatively high, the barrier of the low-barrier region formed by the third doping portion 134 will be broken down, enabling the depletion region to expand to the side of the third doping portion 134 far from the second doping portion 133 to achieve a relatively high photon detection efficiency.

[0064] Therefore, by providing that the single-photon avalanche diode 100 further includes a third doping portion 134 and the doping types of the second doping portion 133 and the third doping portion 134 are opposite, the difference in photon detection efficiency between the cases of a relatively low absolute value of the overbias voltage and a relatively high absolute value of the overbias voltage can be increased. In this way, the photon detection efficiency of the single-photon avalanche diode 100 can be adjusted by adjusting the overbias voltage, and a large change in photon detection efficiency can be achieved within a relatively small overbias voltage adjustment range. For example, a photon detection efficiency adjustment range of more than 20 times can be achieved. Thus, the count rate of the single-photon avalanche diode 100 can remain unsaturated in a strong light environment, and further the output response is linear, which can solve the problem of insufficient dynamic range of the SPAD photodetector in a strong light environment.

[0065] In some embodiments, in combination with Figure 1 , for the single-photon avalanche diode 100 including the third doping portion 134, simulation tests were respectively carried out on the device potential distribution and the avalanche breakdown probability distribution when the overbias voltage V ex is -1.2V and when the overbias voltage V ex is -3.3V. When the overbias voltage V ex is -1.2V, the simulation diagram of the device electrostatic potential distribution of the single-photon avalanche diode 100 is as shown in Figure 3 (a), and the simulation diagram of the avalanche breakdown probability distribution is as shown in Figure 4 (a). When the overbias voltage V ex is -3.3V, the simulation diagram of the device electrostatic potential distribution of the single-photon avalanche diode 100 is as shown in Figure 3 (b), and the simulation diagram of the avalanche breakdown probability distribution is as shown in Figure 4 (b).

[0066] In addition, in the above two cases, the electric potentials of each point on the center line of the single-photon avalanche diode 100 (the position can be referred to the dashed line shown in (a) of Figure 3 and (b) of Figure 3 ) were measured. In the two cases, the curves of the electric potentials of each point on the center line of the single-photon avalanche diode 100 changing with the depth are as shown in Figure 5 and Figure 6 ; among them, Figure 6 is the partial enlarged view of the dashed box in Figure 5 .

[0067] Combined with Figure 1 , referring to Figure 5 and Figure 6 , when V ex is -1.2V, there is a slight rise in the electric potential below the second doping portion 133; when V ex is -3.3V, the electric potential below the second doping portion 133 continues to decrease; this is because when V ex is -1.2V, the third doping portion 134 forms a low-barrier region that is not broken down and forms a blocking effect, while when V ex is -3.3V, the low-barrier region formed by the third doping portion 134 is broken down, enabling the depletion region to continue to expand downward.

[0068] Combined with Figure 1 , referring to (a) in Figure 3 , when V ex is -1.2V, the range of the depletion region is controlled on the side of the third doping portion 134 away from the second surface 130b, indicating that the third doping portion 134 can block the downward expansion of the depletion region, making the depletion region smaller; referring to (b) in Figure 3 , when V ex is -3.3V, the low-barrier region formed by the third doping portion 134 is broken down, enabling the depletion region to continue to expand downward to the side of the third doping portion 134 close to the second surface 130b, making the depletion region larger.

[0069] Combined with Figure 1 , referring to (a) in Figure 4 , when V ex is -1.2V, blocked by the third doping portion 134, the region where the avalanche breakdown probability is greater than 0 is restricted to the side of the third doping portion 134 away from the second surface 130b and is located in a shallower region; referring to (b) in Figure 4 , when V ex is -3.3V, the low-barrier region formed by the third doping portion 134 is broken down, and the region on the side of the third doping portion 134 close to the second surface 130b has an avalanche breakdown probability greater than 0, and the avalanche breakdown probability is relatively strong.

[0070] The embodiments of the present disclosure do not limit the doping type of the third doping portion 134, as long as the requirement that the doping types of the second doping portion 133 and the third doping portion 134 are opposite is satisfied.

[0071] In some examples, as Figure 1 shown, the doping type of the main body portion 131 is N-type, the doping type of the first doping portion 132 is P-type, the doping type of the second doping portion 133 is N-type, and the doping type of the third doping portion 134 is P-type. At this time, elements such as boron, indium, and gallium can be doped on the wafer 130 or the epitaxial layer to form a uniform P-type structure, so that the doped portion of the wafer 130 forms the third doping portion 134. The above doping process is, for example, an ion implantation process or a diffusion process.

[0072] In some embodiments, the doping type of the third doping portion 134 is N-type.

[0073] Through the above settings, a doping process (such as an ion implantation process or a diffusion process) can be used to dope elements such as phosphorus, arsenic, and antimony on the wafer 130 or the epitaxial layer to form a uniform N-type structure, so that the doped portion of the wafer 130 forms the third doping portion 134.

[0074] Since the third doping portion 134 is located on the side of the second doping portion 133 away from the first doping portion 132, the doping depth of the third doping portion 134 is relatively deep. During the process of forming the third doping portion 134 using the N-type doping process, it is easier to form a tail of N-type doping. In this way, compared with the case where the doping type of the third doping portion 134 is P-type, the process difficulty of forming the third doping portion 134 can be reduced, and the process feasibility of manufacturing the single-photon avalanche diode 100 is improved.

[0075] It should be understood that when the third doping portion 134 is provided on the side of the second doping portion 133 away from the first doping portion 132, the third doping portion 134 and the second doping portion 133 may be in direct contact or may be spaced apart.

[0076] In some embodiments, as Figure 1 shown, the second doping portion 133 is in contact with the third doping portion 134.

[0077] By setting it in this way, the third doping portion 134 can form a blocking effect at the surface of the second doping portion 133 away from the first doping portion 132. In this way, when the absolute value of the overbias voltage is relatively low, in the first direction X, the boundary of the depletion region can be limited to the surface of the second doping portion 133 away from the first doping portion 132 (i.e., the contact surface between the second doping portion 133 and the third doping portion 134). In this way, the area of the depletion region can be made smaller, the photon detection efficiency of the single-photon avalanche diode 100 can be made lower, and the change in photon detection efficiency in the case of a relatively low absolute value of the overbias voltage and a relatively high absolute value of the overbias voltage can be made greater.

[0078] Figure 7 Another cross-sectional structure diagram of the single-photon avalanche diode 100 provided by some embodiments of the present disclosure.

[0079] In some embodiments, as Figure 7 shown, the second doping portion 133 is connected to the third doping portion 134 through a partial main body portion 131.

[0080] Exemplarily, in the first direction X, there is a spacing between the third doping portion 134 and the second surface 130b.

[0081] As described above, the third doping portion 134 can be formed by doping elements on the wafer 130 or the epitaxial layer. When there are spacings between the third doping portion 134 and the first surface 130a, and between the third doping portion 134 and the second surface 130b in the first direction X, during the formation of the third doping portion 134, the doping depth needs to be controlled so that the third doping portion 134 is within a set depth range. When the second doping portion 133 is connected to the third doping portion 134 through a partial main body portion 131, during the formation of the third doping portion 134, the doping depth is relatively easy to control, which is beneficial to improving the process feasibility of forming the third doping portion 134.

[0082] Combined with Figure 1 , the present disclosure embodiments do not limit the relative size relationship between the size D1 of the first doping portion 132 in the second direction Y and the size D2 of the second doping portion 133 in the second direction Y. Wherein, the second direction Y is perpendicular to the first direction X.

[0083] In some embodiments, the size D1 of the first doping portion 132 in the second direction Y is less than or equal to the size D2 of the second doping portion 133 in the second direction Y.

[0084] In some cases, combined with Figure 1, there is a certain edge concentration enrichment effect at the edge of the first doping portion 132 in the second direction Y, which makes it easier to generate a stronger electric field between the edge of the first doping portion 132 in the second direction Y and the surrounding structures. When the size D1 of the first doping portion 132 in the second direction Y is less than or equal to the size D2 of the second doping portion 133 in the second direction Y, the distance between the edge of the first doping portion 132 in the second direction Y and the second doping portion 133 is relatively close, making it easy to generate a certain electric field between the two, and premature breakdown is likely to occur at the edge of the first doping portion 132, affecting the detection performance of the single-photon avalanche diode 100.

[0085] In some embodiments, as Figure 1 shown, the size D1 of the first doping portion 132 in the second direction Y is greater than the size D2 of the second doping portion 133 in the second direction Y.

[0086] Exemplarily, the doping concentration of the second doping portion 133 is greater than the doping concentration of the main body portion 131.

[0087] Exemplarily, the orthographic projection of the second doping portion 133 on the second surface 130b is covered by the orthographic projection of the first doping portion 132 on the second surface 130b.

[0088] Through the above settings, the distance between the edge of the first doping portion 132 in the second direction Y and the second doping portion 133 can be made relatively large, which can avoid generating a strong electric field between the two, and further avoid premature breakdown at the edge of the first doping portion 132; moreover, when the doping concentration of the second doping portion 133 is greater than the doping concentration of the main body portion 131, the edge of the first doping portion 132 in the second direction Y can be covered by the main body portion 131 with a lower doping concentration, and the electric field between the two is weak, which can further avoid premature breakdown at the edge of the first doping portion 132, and is beneficial to improving the detection performance of the single-photon avalanche diode 100.

[0089] The present disclosure embodiment does not limit the relative size relationship between the size D2 of the second doping portion 133 in the second direction Y and the size D3 of the third doping portion 134 in the second direction Y.

[0090] In some examples, the size D2 of the second doping portion 133 in the second direction Y is less than or equal to the size D3 of the third doping portion 134 in the second direction Y.

[0091] In some embodiments, as Figure 1 shown, the size D2 of the second doping portion 133 in the second direction Y is greater than the size D3 of the third doping portion 134 in the second direction Y.

[0092] Exemplarily, the orthographic projection of the third doping portion 134 on the second surface 130b is covered by the orthographic projection of the second doping portion 133 on the second surface 130b.

[0093] In some cases, when the absolute value of the overbias voltage is relatively high, the middle portion of the third doping portion 134 is broken down, while the edge portion is not broken down.

[0094] It can be understood that when the absolute value of the overbias voltage is relatively high, during the process of the depletion region expanding towards the side of the third doping portion 134 away from the second doping portion 133, the depletion region also expands towards both sides along the second direction Y (i.e., Figure 1 expanding leftward and rightward in ). When the size D3 of the third doping portion 134 in the second direction Y is relatively large, during the process of the middle portion of the third doping portion 134 being broken down, the edge portion may not be broken down. In this way, the non - broken - down third doping portion 134 may block the expansion of the depletion region along the second direction Y, making the depletion region relatively small when the absolute value of the overbias voltage is relatively high, and may cause the change in the photon detection efficiency to be relatively small when the absolute value of the overbias voltage is relatively low and relatively high.

[0095] Therefore, when the size D2 of the second doping portion 133 in the second direction Y is greater than the size D3 of the third doping portion 134 in the second direction Y, the size D3 of the third doping portion 134 in the second direction Y can be made smaller, so that the third doping portion 134 can be completely broken down when the absolute value of the overbias voltage is relatively high, enabling the depletion region to expand along the second direction Y, and further making the area of the depletion region larger, which can cause a greater change in the photon detection efficiency when the absolute value of the overbias voltage is relatively low and relatively high.

[0096] Hereinafter, an example of the coupling manner between the second electrode 120 and the first doping portion in the single - photon avalanche diode 100 will be described.

[0097] Figure 8 FIG. is a cross - sectional structure diagram of a single - photon avalanche diode 100 provided by some other embodiments of the present disclosure.

[0098] In some embodiments, as Figure 8 shown, the surface of the first doping portion 132 away from the second doping portion 133 forms a part of the first surface 130a; the first doping portion 132 is in contact with the second electrode 120.

[0099] Through the above arrangement, the first doping portion 132 is in direct contact with the second electrode 120, which can simplify the structure of the single - photon avalanche diode 100.

[0100] In some embodiments, as Figure 1 and Figure 2As shown, the wafer 130 further includes a fourth doped portion 135. The fourth doped portion 135 is in contact with the surface of the first doped portion 132 that is away from the second doped portion 133 and is wrapped by the first doped portion 132. The doping type of the fourth doped portion 135 is the same as that of the first doped portion 132, and the doping concentration of the fourth doped portion 135 is greater than that of the first doped portion 132. The surface of the fourth doped portion 135 that is away from the second doped portion 133 forms a part of the first surface 130a; the fourth doped portion 135 is in contact with the second electrode 120.

[0101] Exemplarily, the surface of the fourth doped portion 135 that is close to the second doped portion 133, as well as the side surface of the fourth doped portion 135, are wrapped by the first doped portion 132. Moreover, the surface of the first doped portion 132 that is away from the second doped portion and wraps around the side surface of the fourth doped portion 135 forms a part of the first surface 130a.

[0102] It should be understood that in the case where the doping type of the fourth doped portion 135 is the same as that of the first doped portion 132, the doping type of the fourth doped portion 135 is the same as that of the third doped portion 134.

[0103] Exemplarily, the doping concentration of the fourth doped portion 135 is greater than that of the third doped portion 134.

[0104] In some examples, when the first doped portion 132 is in contact with the second electrode 120, the doping concentration of the first doped portion 132 is relatively high, making the concentration enrichment effect at the edge portion of the first doped portion 132 in the second direction Y relatively strong, and it is easy to have premature breakdown at the corners with other surrounding structures (such as the fifth doped portion 136 and / or the sixth doped portion 137 described in detail below). To avoid the occurrence of premature breakdown at the corners, in some cases, the spacing between the first doped portion 132 and other surrounding structures is set within a relatively large range, resulting in a relatively small device size of the single-photon avalanche diode 100.

[0105] In still other examples, when the first doped portion 132 is reused as the second electrode 120, the first doped portion 132 is closer to the first surface 130a, making the PN junction located in a relatively shallow region. During the avalanche multiplication effect, the carriers released from the defect levels near the surface of the wafer 130 (such as the silicon surface) are easily introduced into the main junction region, resulting in an increase in the dark count rate, generating certain noise, and reducing the signal-to-noise ratio of the device of the single-photon avalanche diode 100.

[0106] Understandably, in the case where the wafer 130 further includes a fourth doping portion 135, on the one hand, the doping concentration of the first doping portion 132 can be relatively low, so that the concentration enrichment effect at the edge portion of the first doping portion 132 in the second direction Y is weak, the probability of the occurrence of the corner premature breakdown phenomenon can be reduced, and the device size of the single-photon avalanche diode 100 can be made smaller. On the other hand, the first doping portion 132 can be made further away from the first surface 130a. In this way, during the avalanche multiplication effect, the carriers released from the defect energy levels near the surface of the wafer 130 are less likely to enter the main junction region, and the signal-to-noise ratio of the device of the single-photon avalanche diode 100 can be improved.

[0107] Hereinafter, an example of the coupling manner between the first electrode 110 and the main body portion 131 in the single-photon avalanche diode 100 will be described.

[0108] In some embodiments, as Figure 1 and Figure 2 shown, the wafer 130 further includes a fifth doping portion 136. The fifth doping portion 136 is provided on one side of the main body portion 131 and is connected to the main body portion 131. The surface of the fifth doping portion 136 away from the second surface 130b forms a part of the first surface 130a. The fifth doping portion 136 and the first doping portion 132 are arranged at intervals. The doping type of the fifth doping portion 136 is the same as that of the main body portion 131, and the doping concentration of the fifth doping portion 136 is greater than that of the main body portion 131; the fifth doping portion 136 is in contact with the first electrode 110.

[0109] Exemplarily, the main body portion 131 is a part of the epitaxial layer of the wafer 130, and the doping concentration of the fifth doping portion 136 can be greater than that of the main body portion 131.

[0110] Through the above arrangement, compared with the case where the first electrode 110 is in contact with the main body portion 131, the doping concentration of the portion in contact with the first electrode 110 can be relatively high, the electrical connection effect between the first electrode 110 and the main body portion 131 can be improved, and it is beneficial to improve the detection performance of the single-photon avalanche diode 100.

[0111] The present disclosure embodiment does not limit the doping concentration and doping depth of the fifth doping portion 136.

[0112] In some examples, the difference between the doping concentration of the fifth doping portion 136 and that of the main body portion 131 is relatively large, and the doping depth of the fifth doping portion 136 is relatively shallow, so that the ohmic contact effect between the fifth doping portion 136 and the main body portion 131 is relatively poor.

[0113] For this reason, in some embodiments, as Figure 1 and Figure 2As shown, the wafer 130 further includes a sixth doped portion 137. The sixth doped portion 137 is disposed between the fifth doped portion 136 and the main body portion 131 and wraps the fifth doped portion 136. The sixth doped portion 137 is spaced apart from the first doped portion 132. The fifth doped portion 136 and the sixth doped portion 137 have the same doping type. The doping concentration of the sixth doped portion 137 is greater than that of the main body portion 131 and less than that of the fifth doped portion 136.

[0114] Exemplarily, the surface of the fifth doped portion 136 close to the second surface 130b and the side surface of the fifth doped portion 136 are wrapped by the sixth doped portion 137. Moreover, the surface of the sixth doped portion 137 that wraps around the side surface of the fifth doped portion 136 and is away from the second surface 130b forms a part of the first surface 130a.

[0115] In some examples, the doping type of the main body portion 131 is N-type, the doping type of the first doped portion 132 is P-type, the doping type of the second doped portion 133 is N-type, the doping type of the third doped portion 134 is P-type, the doping type of the fifth doped portion 136 is N-type, and the doping type of the sixth doped portion 137 is N-type.

[0116] In some examples, the doping type of the main body portion 131 is P-type, the doping type of the first doped portion 132 is N-type, the doping type of the second doped portion 133 is P-type, the doping type of the third doped portion 134 is N-type, the doping type of the fifth doped portion 136 is P-type, and the doping type of the sixth doped portion 137 is P-type.

[0117] With the above arrangement, the doping concentrations of the fifth doped portion 136, the sixth doped portion 137, and the main body portion 131 decrease in sequence. In this way, the sixth doped portion 137 can form a transition region between the fifth doped portion 136 and the main body portion 131, which can improve the electrical connection effect between the fifth doped portion 136 and the main body portion 131 and is beneficial to improving the detection performance of the single-photon avalanche diode 100.

[0118] The present disclosure does not limit the shapes of the fifth doped portion 136 and the sixth doped portion 137. For example, the fifth doped portion 136 can be a strip-shaped doped portion, and the number of the fifth doped portions 136 can be one or more.

[0119] Figure 9 and Figure 10 FIG. is a position reference diagram of the orthographic projection on the second surface 130b of some structures of another single-photon avalanche diode 100 provided by some embodiments of the present disclosure.

[0120] In some embodiments, such as Figure 1 、 Figure 2 、 Figure 9 andFigure 10 As shown, the fifth doping portion 136 and the sixth doping portion 137 are annular structures, and the first doping portion 132, the second doping portion 133, the third doping portion 134, and the second electrode 120 are disposed inside the fifth doping portion 136 and also inside the sixth doping portion 137. The wafer 130 further includes: an isolation portion 138 surrounding the sixth doping portion 137.

[0121] Exemplarily, the cross-sectional morphology of the fifth doping portion 136 and the cross-sectional morphology of the sixth doping portion 137 may be the same or different. For example, as Figure 2 shown, the fifth doping portion 136 is an annular structure with a circular inner circle and a circular outer circle, and the sixth doping portion 137 is an annular structure with a circular inner circle and a square outer circle; or for another example, as Figure 10 shown, both the fifth doping portion 136 and the sixth doping portion 137 are annular structures with a square inner circle and a square outer circle.

[0122] Exemplarily, as Figure 1 shown, the isolation portion 138 penetrates the wafer 130.

[0123] Exemplarily, the material of the isolation portion 138 includes an isolation medium, and the material of the isolation medium may be polysilicon or tungsten metal.

[0124] In some examples, as Figures 11 to 13 shown, the single-photon avalanche diode 100 is the single-photon avalanche diode 100 in the photodetector 200, and the photodetector includes a plurality of (for example, a plurality arranged in an array) single-photon avalanche diodes 100.

[0125] By providing the fifth doping portion 136 as an annular structure, an annular electric field can be formed between the first electrode 110 and the second electrode 120, and the distribution range of the electric field is relatively large, which is beneficial to improving the detection efficiency of the single-photon avalanche diode 100. By providing that the wafer 130 further includes the isolation portion 138, signal interference between the single-photon avalanche diode 100 and adjacent devices (for example, adjacent single-photon avalanche diodes 100) can be avoided, which is beneficial to improving the detection accuracy of the single-photon avalanche diode 100.

[0126] As described above, the sixth doping portion 137 and the first doping portion 132 are spaced apart. Among them, the present disclosure embodiment does not limit the size of the distance between the sixth doping portion 137 and the first doping portion 132. In practical applications, the size of the distance between the sixth doping portion 137 and the first doping portion 132 can be determined according to the device size and doping conditions.

[0127] In some embodiments, as Figure 1As shown, the isolation part 138 includes a first outer boundary 138a and a second outer boundary 138b that are opposite to each other in the second direction Y, the second direction Y is perpendicular to the first direction X, and the first outer boundary 138a and the second outer boundary 138b have a first distance L1 in the second direction Y. The boundary where the first doping part 132 and the sixth doping part 137 are close to each other has a second distance L2 in the second direction Y. The ratio range of the second distance L2 to the first distance L1 is 0.02 to 0.5.

[0128] Exemplarily, the ratio of the second distance L2 to the first distance L1 can be 0.02, 0.05, 0.1, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.44, or 0.5, etc., and there is no limitation here.

[0129] It can be understood that when the ratio of the second distance L2 to the first distance L1 is relatively low (for example, less than 0.02), the distance between the first doping part 132 and the sixth doping part 137 is small, making it easy for premature breakdown to occur between the edge part of the first doping part 132 and the sixth doping part 137. When the ratio of the second distance L2 to the first distance L1 is relatively high (for example, greater than 0.5), the distance between the first doping part 132 and the sixth doping part 137 is large, which may make the size of the first doping part 132 relatively small, making the area of the PN junction formed by the first doping part 132 and the second doping part 133 small, and may make the detection efficiency of the single-photon avalanche diode 100 relatively low. Therefore, by setting the ratio range of the second distance L2 to the first distance L1 to be 0.02 to 0.5, on the basis of ensuring the detection efficiency of the single-photon avalanche diode 100, premature breakdown between the edge part of the first doping part 132 and the sixth doping part 137 can be avoided.

[0130] The embodiments of the present disclosure do not limit the shapes of the orthographic projections of the first doping part 132, the second doping part 133, the third doping part 134, the fourth doping part 135, and the fifth doping part 136 on the second surface 130b. Moreover, the shapes of any two of the first doping part 132, the second doping part 133, the third doping part 134, and the fourth doping part 135 can be the same or different.

[0131] In some embodiments, the shape of the orthographic projection of any one of the first doping part 132, the second doping part 133, the third doping part 134, and the fourth doping part 135 on the second surface 130b includes a circle, a square, or a regular octagon. The shape of the orthographic projection of the fifth doping part 136 on the second surface 130b includes an annulus, the inner boundary of the annulus is circular, square, or regular octagonal, and the outer boundary of the annulus is circular, square, or regular octagonal.

[0132] In some examples, the shapes of the positive projections of the first doping portion 132, the second doping portion 133, the third doping portion 134, and the fourth doping portion 135 on the second surface 130b are the same. Exemplarily, as Figure 2 shown, the shapes of the positive projections of the first doping portion 132, the second doping portion 133, the third doping portion 134, and the fourth doping portion 135 on the second surface 130b are all circular. Again exemplarily, as Figure 9 shown, the shapes of the positive projections of the first doping portion 132, the second doping portion 133, the third doping portion 134, and the fourth doping portion 135 on the second surface 130b are all regular octagons. Again exemplarily, as Figure 10 shown, the shapes of the positive projections of the first doping portion 132, the second doping portion 133, the third doping portion 134, and the fourth doping portion 135 on the second surface 130b are all square.

[0133] In still some other examples, the shapes of the positive projections of at least two of the first doping portion 132, the second doping portion 133, the third doping portion 134, and the fourth doping portion 135 on the second surface 130b are different from each other.

[0134] In some examples, the shapes of the inner boundary and the outer boundary of the positive projection (ring shape) of the fifth doping portion 136 on the second surface 130b are similar. Exemplarily, as Figure 2 shown, the inner boundary of the ring is circular and the outer boundary of the ring is circular. Again exemplarily, as Figure 9 shown, the inner boundary of the ring is a regular octagon and the outer boundary of the ring is a regular octagon. Again exemplarily, as Figure 10 shown, the inner boundary of the ring is square and the outer boundary of the ring is square.

[0135] In still some other examples, the shapes of the inner boundary and the outer boundary of the positive projection (ring shape) of the fifth doping portion 136 on the second surface 130b are different. For example, the inner boundary of the ring is circular and the outer boundary of the ring is square. Another example is that the inner boundary of the ring is a regular octagon and the outer boundary of the ring is square.

[0136] With the above settings, it is convenient to optimize the spatial positions of the first doping portion 132, the second doping portion 133, the third doping portion 134, the fourth doping portion 135, and the fifth doping portion 136, making the layout of the first doping portion 132, the second doping portion 133, the third doping portion 134, the fourth doping portion 135, and the fifth doping portion 136 on the wafer 130 more reasonable. Moreover, when the shapes of the orthographic projections of the first doping portion 132, the second doping portion 133, the third doping portion 134, and the fourth doping portion 135 on the second surface 130b are circular or regular octagons, compared with the case where the shapes of the orthographic projections of the first doping portion 132, the second doping portion 133, the third doping portion 134, and the fourth doping portion 135 on the second surface 130b are square, the radius of curvature of the first doping portion 132, the second doping portion 133, the third doping portion 134, the fourth doping portion 135, and the fifth doping portion 136 at the edge position can be made larger, the electric field strength in the edge region can be reduced, and premature breakdown at the edge can be avoided.

[0137] Taking the case where the doping type of the third doping portion 134 is N-type as an example, an exemplary introduction to the manufacturing method of the single-photon avalanche diode 100 will be given. It should be understood that the operations shown in the manufacturing method are not exhaustive, and other operations can also be performed before, after, or between any of the shown operations.

[0138] In some embodiments, the manufacturing method of the single-photon avalanche diode 100 includes S1: S1: A P-type epitaxial layer (P-Epitaxy, P-EPI) is formed on a wafer substrate (P-substrate, P-SUB) by epitaxial growth.

[0139] Exemplarily, the resistivity range of the wafer substrate is 0.01 Ω·cm to 100 Ω·cm, such as 0.01 Ω·cm, 0.1 Ω·cm, 0.5 Ω·cm, 1 Ω·cm, 10 Ω·cm, 20 Ω·cm, 50 Ω·cm, or 100 Ω·cm, etc.

[0140] Exemplarily, the resistivity range of the P-type epitaxial layer is 0.1 Ω·cm to 1000 Ω·cm, such as 0.1 Ω·cm, 0.3 Ω·cm, 0.5 Ω·cm, 1 Ω·cm, 10 Ω·cm, 50 Ω·cm, 100 Ω·cm, 300 Ω·cm, 500 Ω·cm, or 1000 Ω·cm, etc.

[0141] S2: P-type implantation is performed on the central region of the P-type epitaxial layer. For example, boron (B) atoms are implanted to form the second doping portion 133.

[0142] Exemplarily, the implantation energy range of the P-type implantation in S2 is 300 keV to 800 keV, such as 300 keV, 400 keV, 500 keV, 600 keV, 700 keV or 800 keV, etc.

[0143] Exemplarily, the implantation dose range of the P-type implantation in S2 is 1×10 12 cm -2 ~1×10 13 cm -2 , such as 1×10 12 cm -2 , 2×10 12 cm -2 , 4×10 12 cm -2 , 6×10 12 cm -2 , 8×10 12 cm -2 or 1×10 13 cm -2 etc.

[0144] S3: Perform N-type implantation on the P-type epitaxial layer on the side of the second doping portion 133 close to the first surface 130a. For example, implant phosphorus (P) atoms or arsenic (As) atoms to form the first doping portion 132.

[0145] Exemplarily, the implantation energy range of the N-type implantation in S3 is 100 keV to 500 keV, such as 100 keV, 200 keV, 300 keV, 350 keV, 400 keV or 500 keV, etc.

[0146] Exemplarily, the implantation dose range of the N-type implantation in S3 is 4×10 12 cm -2 ~3×10 13 cm -2 , such as 4×10 12 cm -2 , 6×10 12 cm -2 , 8×10 12 cm -2 , 9×10 12 cm -2 , 1×10 13 cm -2 or 3×10 13 cm -2 etc.

[0147] S4: Based on the N-type implantation in S3, perform a second N-type implantation to form the third doping portion 134 on the side of the second doping portion 133 away from the first doping portion 132.

[0148] Exemplarily, the implantation dose of the N-type implantation in S4 is higher than that of the N-type implantation in S3. Exemplarily, the implantation energy of the N-type implantation in S4 is higher than that of the N-type implantation in S3. By setting it in this way, the trailing of the N-type doping can be utilized to form the third doped portion 134.

[0149] Exemplarily, the implantation energy range of the N-type implantation in S4 is 100 keV to 500 keV, such as 100 keV, 200 keV, 300 keV, 340 keV, 400 keV, or 500 keV, etc.

[0150] Exemplarily, the implantation dose range of the N-type implantation in S4 is 5×10 12 cm -2 ~5×10 13 cm -2 For example, it is 5×10 12 cm -2 , 6×10 12 cm -2 , 8×10 12 cm -2 , 1×10 13 cm -2 , 3×10 13 cm -2 or 5×10 13 cm -2 etc.

[0151] S5: Perform a third N-type implantation on the P-type epitaxial layer on the side of the second doped portion 133 close to the first surface 130a. For example, implant phosphorus (P) atoms or arsenic (As) atoms to form a fourth doped portion 135, and the fourth doped portion 135 forms the second electrode 120.

[0152] S6: Perform a P-type implantation on the P-type epitaxial layer on both sides of the first doped portion 132. For example, implant boron (B) atoms to form an initial sixth doped portion.

[0153] S7: Perform a P-type implantation on the central region of the initial sixth doped portion. For example, implant boron (B) atoms with a higher concentration to form a fifth doped portion 136. The region of the initial sixth doped portion that is not subjected to the P-type implantation in S7 forms a sixth doped portion 137, and the sixth doped portion 137 forms the first electrode 110.

[0154] S8: Perform a deep trench etching on the P-type epitaxial layer on both sides of the sixth doped portion 137 to form a full deep trench isolation (FDTI), and fill polysilicon or tungsten metal in the full deep trench isolation to form an isolation portion 138.

[0155] It should be understood that the above S6 - S7 can be carried out after S1 - S5 or before S1 - S5.

[0156] It should be understood that the above S8 can be carried out after S1 - S7 or before S1 - S7.

[0157] It should be noted that the preparation methods listed above are examples of the preparation method of the single - photon avalanche diode 100, rather than limitations on the preparation method of the single - photon avalanche diode 100.

[0158] Some embodiments of the present disclosure also provide a photodetector 200, as Figures 11 to 14 shown, the photodetector 200 includes at least one single - photon avalanche diode 100 provided by the above - mentioned disclosed embodiments and a logic circuit 211; the logic circuit 211 is respectively coupled to the first electrode 110 and the second electrode 120.

[0159] Exemplarily, the logic circuit 211 can be configured to: apply voltage signals to the first electrode 110 and the second electrode 120 respectively.

[0160] The single - photon avalanche diode 100 can convert an optical signal into an electrical signal; in some examples, the logic circuit 211 can be configured to: receive the electrical signal (e.g., read out the charge amount) converted by the single - photon avalanche diode 100, thereby realizing the function of photodetection.

[0161] Exemplarily, as Figures 11 to 13 shown, the photodetector 200 includes a plurality of single - photon avalanche diodes 100 provided by the above - mentioned disclosed embodiments, and the plurality of single - photon avalanche diodes 100 are arranged in an array (e.g., 4×4, 100×100 or 1280×960), forming a photodiode array. At this time, each single - photon avalanche diode 100 in the photodiode array can constitute a pixel of the photodetector 200, or a plurality of (e.g., 2×2 or 4×4) single - photon avalanche diodes 100 in the photodiode array can constitute a macro - pixel of the photodetector 200. When the photodetector 200 includes a plurality of single - photon avalanche diodes 100, the plurality of single - photon avalanche diodes 100 can share the wafer 130; two adjacent single - photon avalanche diodes 100 can share the isolation part 138.

[0162] In some embodiments, the photodetector 200 may further include an analog - to - digital conversion circuit, a comparison circuit or an amplification circuit, etc., so as to be able to perform analog - to - digital conversion, comparison or amplification processing on the electrical signal from the single - photon avalanche diode 100 and output the processed electrical signal.

[0163] In some embodiments, the photodetector 200 further includes a printed circuit board (PCB, Printed Circuit Board), and processing circuits such as a readout circuit, a quenching circuit, an analog-to-digital conversion circuit, a comparison circuit, and an amplification circuit can be disposed on the printed circuit board. In some embodiments, the number of processing circuits is multiple and is used to perform different processes on the received electrical signals. It can be understood that the multiple processing circuits can be disposed on the same printed circuit board or can be respectively disposed on multiple different printed circuit boards.

[0164] In some examples, the photodetector 200 further includes one or more microlenses 220, and one microlens 220 is disposed on the photon detection surface of a single-photon avalanche diode 100 (for example, the second surface 130b of the wafer 130). The microlens 220 can be configured to: enhance photon absorption.

[0165] Here, the photon detection surface can be understood as the surface of the single-photon avalanche diode 100 that first receives photons. Exemplarily, the photon detection surface of the single-photon avalanche diode 100 can be the first surface 130a or the second surface 130b.

[0166] The beneficial effects achievable by a photodetector 200 provided in some embodiments of the present disclosure are the same as those achievable by a single-photon avalanche diode 100 provided in the above technical solution, and will not be elaborated herein.

[0167] In some embodiments, as Figure 14 shown, the photon detection surface of the single-photon avalanche diode 100 is the second surface 130b, and the logic circuit 211 is connected to the first surface 130a of the single-photon avalanche diode 100.

[0168] When the photon detection surface of the single-photon avalanche diode 100 is the second surface 130b, the photodetector 200 including the single-photon avalanche diode 100 has a back-illuminated structure.

[0169] Exemplarily, as Figure 14 shown, the photodetector 200 may further include an inverted pyramid structure 230 disposed on the second surface 130b, and the inverted pyramid structure 230 can be configured to: enhance photon absorption.

[0170] Exemplarily, as Figure 14 shown, the photodetector 200 may further include a passivation layer 240 disposed on the side of the inverted pyramid structure 230 away from the first surface 130a. In this case, the microlens 220 can be disposed on the passivation layer 240, and the passivation layer 240 can be configured to: reduce photon reflection and enhance photon absorption.

[0171] In some examples, asFigure 14 As shown, the logic circuit 211 is the logic circuit 211 disposed on the logic wafer 210. Exemplarily, the logic wafer 210 includes a substrate 212, and the logic circuit 211 is disposed on the substrate 212.

[0172] Exemplarily, as Figure 14 shown, the logic wafer 210 further includes a first interconnect structure 213 (e.g., a copper - copper interconnect structure) disposed between the logic circuit 211 and the first surface 130a; between the logic circuit 211 and the first electrode 110, and between the logic circuit 211 and the second electrode 120, electrical connection can be achieved through the first interconnect structure 213.

[0173] Exemplarily, as Figure 14 shown, the logic wafer 210 further includes one or more first dielectric layers 214 disposed between the first interconnect structure 213 and the first surface 130a. Metal patterns 2141 (e.g., metal traces) are distributed in the first dielectric layer 214. Between the first interconnect structure 213 and the first electrode 110, and between the first interconnect structure 213 and the second electrode 120, electrical connection can be achieved through one or more metal patterns 2141.

[0174] Exemplarily, as Figure 14 shown, in the logic wafer 210, a second dielectric layer 215 is disposed between the first dielectric layer 214 and the first surface 130a, and the first electrode 110 and the second electrode 120 are disposed within the second dielectric layer 215.

[0175] Exemplarily, in practical applications, according to the photon detection efficiency and the spacing requirements between the first electrode 110 and the second electrode 120, the size and area of the first electrode 110 and / or the second electrode 120 can be set. For example, on the basis of making the distance between the first electrode 110 and the second electrode 120 greater than a certain spacing (to avoid short - circuit between the two electrodes), the area of the first electrode 110 and / or the second electrode 120 can be set within a relatively large range, so that photons passing through the wafer 130 and hitting the first electrode 110 and / or the second electrode 120 are reflected back into the wafer 130 to form secondary absorption, thereby enhancing the photon detection efficiency. Moreover, the larger the area of the first electrode 110 and the second electrode 120, the stronger the effect of enhanced absorption.

[0176] Exemplarily, the photodetector 200 may further include at least two through vias (e.g., Through Silicon Via, TSV) formed in the wafer 130. A through contact 250 is disposed in the through via, and one end of the through contact 250 away from the second surface 130b is connected to the logic circuit 211. Among the at least two through contacts 250, one end of a through contact 250 away from the logic wafer 210 is connected to an anode pad 261, and the anode pad 261 is at least used to access an anode signal to the single-photon avalanche diode 100; another end of a through contact 250 away from the logic wafer 210 is connected to a cathode pad 262, and the cathode pad 262 is at least used to access a cathode signal to the single-photon avalanche diode 100.

[0177] It can be understood that through the arrangement of the logic circuit 211 connected to the first surface 130a of the single-photon avalanche diode 100, the wafer (e.g., logic wafer) including the logic circuit 211 can be stacked with the wafer 130 along the first direction X. In this way, the geometric fill factor and detection efficiency of the photodetector 200 can be improved.

[0178] Some embodiments of the present disclosure also provide a detection device 300, as Figure 15 shown, the detection device 300 includes a photodetector 200 provided by the above-disclosed embodiments.

[0179] The detection device 300 may include a security inspection device, a medical detection device, an industrial non-destructive testing device, etc. The detection device 300 can emit light, receive the light passing through the object to be detected, convert the received optical signal into an electrical signal, and determine the internal image information and external image information of the object to be detected according to the electrical signal, so as to achieve the detection function. The specific form of the detection device 300 in the embodiments of the present disclosure is not particularly limited, and the structure of the detection device 300 will be illustrated by way of example below.

[0180] In some embodiments, as Figure 15 shown, the detection device 300 includes a transmitter 310, a photodetector 200, and a processor 320, and the processor 320 is electrically connected to the photodetector 200.

[0181] The transmitter 310 is used to emit light, and the type of light emitted by the transmitter 310 is not limited in the embodiments of the present disclosure. In some embodiments, the transmitter 310 may be used to emit invisible light, such as X-rays or gamma rays, etc., ensuring the penetration ability of the light to the object to be detected, thereby improving the detection accuracy of the detection device 300. In still other embodiments, the transmitter 310 may also be used to emit visible light.

[0182] In some embodiments, the number of transmitters 310 can be multiple, and the multiple transmitters 310 are respectively arranged at different positions, so as to be able to emit light to the object to be detected from different positions, improving the reliability of the detection device 300 in use.

[0183] In some embodiments, the number of photodetectors 200 can be multiple, so as to be able to receive light from different directions.

[0184] The above-mentioned processor 320 is electrically connected to the photodetector 200. The processor 320 can be used to receive the electrical signals from the photodetector 200, and generate internal image information and external image information of the object to be detected according to the electrical signals from the photodetector 200. In some embodiments, the processor 320 can be a central processing unit (CPU, Central Processing Unit) or a graphics processing unit (GPU, Graphic Processing Unit).

[0185] In some embodiments, after the processor 320 generates the image information of the object to be detected, the image information can be transmitted to the outside of the detection device 300. In still other embodiments, the detection device 300 can further include a display device, and the display device is used to display the image information generated by the processor 320. In this way, the user can intuitively obtain the internal image information and external image information of the object to be detected through the display device, improving the convenience of use of the detection device 300.

[0186] The beneficial effects that a detection device 300 provided by some embodiments of the present disclosure can achieve are the same as those that a photodetector 200 provided by the above technical solution can achieve, and will not be elaborated here.

[0187] The above is only the specific implementation manner of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present disclosure, and all should be covered by the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A single-photon avalanche diode, characterized in that, Comprising a first electrode, a second electrode, and a wafer; the first electrode and the second electrode are spaced apart; The wafer includes a first surface and a second surface that are opposite in a first direction, and the first direction is the thickness direction of the wafer; the wafer further includes: A main body portion coupled to the first electrode; A first doped portion and a second doped portion stacked in the first direction; the first doped portion is farther from the second surface than the second doped portion; the first doped portion and the second doped portion form a PN junction connected to the main body portion, and the doping types of the first doped portion and the main body portion are opposite; the first doped portion is coupled to the second electrode; A third doped portion provided on a side of the second doped portion away from the first doped portion; the doping types of the second doped portion and the third doped portion are opposite.

2. The single-photon avalanche diode according to claim 1, wherein The second doped portion is in contact with the third doped portion.

3. The single-photon avalanche diode according to claim 1, characterized in that, The second doped portion and the third doped portion are connected through a part of the main body portion.

4. The single-photon avalanche diode according to claim 1, wherein The size of the first doped portion in a second direction is greater than the size of the second doped portion in the second direction, and the second direction is perpendicular to the first direction.

5. The single-photon avalanche diode according to claim 1, wherein The size of the second doped portion in a second direction is greater than the size of the third doped portion in the second direction, and the second direction is perpendicular to the first direction.

6. The single-photon avalanche diode according to claim 1, characterized in that The surface of the first doped portion away from the second doped portion forms a part of the first surface; the first doped portion is in contact with the second electrode.

7. The single-photon avalanche diode according to claim 1, characterized in that, The wafer further includes: A fourth doped portion in contact with the surface of the first doped portion away from the second doped portion and wrapped by the first doped portion; the doping type of the fourth doped portion is the same as that of the first doped portion, and the doping concentration of the fourth doped portion is greater than that of the first doped portion; the surface of the fourth doped portion away from the second doped portion forms a part of the first surface; the fourth doped portion is in contact with the second electrode.

8. The single-photon avalanche diode according to any one of claims 1 to 7, characterized in that, The wafer further includes: A fifth doped portion provided on one side of the main body portion and connected to the main body portion; the surface of the fifth doped portion away from the second surface forms a part of the first surface; the fifth doped portion is spaced apart from the first doped portion; the doping type of the fifth doped portion is the same as that of the main body portion, and the doping concentration of the fifth doped portion is greater than that of the main body portion; the fifth doped portion is in contact with the first electrode.

9. The single-photon avalanche diode according to claim 8, wherein, The wafer further includes: A sixth doped portion provided between the fifth doped portion and the main body portion and wrapping the fifth doped portion; the sixth doped portion is spaced apart from the first doped portion; the doping types of the fifth doped portion and the sixth doped portion are the same, the doping concentration of the sixth doped portion is greater than that of the main body portion and less than that of the fifth doped portion.

10. The single-photon avalanche diode according to claim 9, wherein The fifth doped portion and the sixth doped portion are in a ring structure, and the first doped portion, the second doped portion, the third doped portion, and the second electrode are provided inside the fifth doped portion and inside the sixth doped portion; The wafer further includes: an isolation portion surrounding the sixth doped portion.

11. The single-photon avalanche diode according to claim 10, characterized in that, The isolation portion includes a first outer boundary and a second outer boundary opposite to each other in a second direction perpendicular to the first direction, and the first outer boundary and the second outer boundary have a first distance in the second direction; The boundary where the first doped portion and the sixth doped portion approach each other has a second distance in the second direction, and the ratio range of the second distance to the first distance is 0.02 to 0.

5.

12. The single-photon avalanche diode according to claim 8, wherein, Any one of the first doped portion, the second doped portion, the third doped portion, and the fourth doped portion has a shape of a circle, a square, or a regular octagon in the orthographic projection on the second surface; The orthographic projection of the fifth doped portion on the second surface has a shape of a ring, the inner boundary of the ring is a circle, a square, or a regular octagon, and the outer boundary of the ring is a circle, a square, or a regular octagon.

13. The single-photon avalanche diode according to any one of claims 1 to 7, characterized in that, The doping type of the third doped portion is N-type.

14. A photodetector, characterized in that, Comprising: At least one single-photon avalanche diode as described in any one of claims 1 to 13; A logic circuit respectively coupled to the first electrode and the second electrode.

15. The photodetector according to claim 14, characterized in that, The photon detection surface of the single-photon avalanche diode is the second surface; the logic circuit is connected to the first surface of the single-photon avalanche diode.

16. A detection device, characterized in that: Comprising a photodetector as described in claim 14 or 15.

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